Photoreactive noxious substance purging agent and photoreactive noxious substance purging material using the agent

Disclosed is a photoreactive noxious substance purging agent comprising a photoreactive semiconductor, a carrier, and a microfibrillated microfiber. In this photoreactive noxious substance purging agent, loss of the photoreaction effective surface of the photoreactive semiconductor can be held down to the minimum and a sufficient noxious substance removing characteristics can be exhibited.

BACKGROUND OF THE INVENTION 
The present invention relates to a photoreactive noxious substance purging 
agent capable of decomposing noxious substances in air and water such as 
malodor or bacteria utilizing a photocatalytic decomposition action of 
photoreactive semiconductors and to a photoreactive noxious substance 
purging material using the said removing agent. 
Recently, with growing of interest in environmental problems, demands for 
removing bad smell in everyday life and removing noxious substances 
contained in water such as industrial waste water in a low concentration 
have increased. Hitherto, removal of such low concentration noxious 
substances has been carried out using composite inorganic adsorbents such 
as active carbon, active silica, active alumina and metal oxides. These 
adsorbents are used as powder or in the form of a sheet as proposed in 
Japanese Utility Model Kokai No. 59-119324. 
However, when these adsorbents are used for removal of noxious substances, 
the adsorptivity gradually decreases according as they adsorb the noxious 
substances, and regeneration of the adsorbents requires high-temperature 
treatments. Therefore, when practical adsorptivity has been lost, the 
adsorbents must be changed, and, for this reason, the period for which the 
adsorbents can act effectively must be ascertained. Thus, there are 
various problems in use of these adsorbents. 
Recently, removal of noxious substances using photoreactive semiconductors 
has been noticed. For example, Cundall et al report in J. Oil. Chem. 
Assoc., 61, 351 (1978) that when ultraviolet light is irradiated using 
titanium oxide, alcohol in the mixed system of water and alcohol is 
decomposed. Furthermore, Japanese Patent Kokai No. 61-135669 discloses a 
process of decomposing sulfur compounds which are malodorous substances by 
irradiating titanium oxide or zinc oxide with ultraviolet light. 
Moreover, Japanese Patent Kokoku No. 2-62297 discloses a process of 
removing low concentration nitrogen oxides using a mixture of titanium 
oxide and active carbon. The decomposition of malodorous substances with 
photoreactive semiconductors such as titanium oxide and zinc oxide is 
based on photocatalytic oxidizing action of the photoreactive 
semiconductors on the malodorous substances contacting with the 
semiconductors due to excitation with activation rays. Therefore, the 
photoconductive semiconductors are not consumed or deteriorated owing to 
the decomposition of the malodorous substances. Accordingly, the ability 
of them does not substantially lower as far as they are exposed to light, 
and they have greater advantages than the above-mentioned adsorbents. 
Since the decomposition ability of these photoreactive semiconductors 
increases with increase in the chance of contact with the malodorous 
substances in view of the above-mentioned decomposition mechanism, the 
most effective form of use is powder by which the greatest contact area 
with a gas can be obtained. However, in the case of removing noxious 
substances in gas phase, powder is practically difficult to handle. In 
general, photoreactive semiconductors having photocatalytic ability have a 
particle size of 0.3 .mu.m or less, and when they are merely wrapped with 
a paper or nonwoven fabric, the particles fall off therefrom. When these 
fine particles are handled as a powder, they strongly adhere to the skin 
of hands, etc. and can be removed with difficulty or they fly up in air. 
Especially when they are incorporated into a deodorizing device together 
with a light irradiating device, they must be subjected to some 
processings to improve the handleability. 
As an example of improving the handleability of photoreactive 
semiconductors, Japanese Patent Kokai No. 1-234729 discloses an 
air-conditioner in which is incorporated a photoreactive semiconductor 
layer composite comprising a titanium oxide (a photoreactive 
semiconductor)-supporting honeycomb active carbon. In this conditioner, a 
special honeycomb active carbon is necessary for supporting titanium oxide 
and increasing the photoreaction efficiency. Moreover, a special step is 
needed to hold titanium oxide on and in the honeycom and a spongy buffer 
must be used for preventing titanium oxide from falling off. 
Japanese Patent Kokai No. 3-233100 discloses a ventilation equipment for 
driveway tunnels which comprises an electrostatic precipitator for 
removing particles of soot in contaminated air and a noxious gas remover 
for removing noxious gases in contaminated air. The noxious gas remover 
comprises a mixture of titanium oxide and active carbon and a light source 
for irradiating the mixture with a light of 300 nm or longer in 
wavelength. Since the titanium oxide is fixed by an adhesive, there is the 
problem that the exposed surface of titanium oxide which directly contacts 
with noxious gases reduces. Furthermore, since the titanium oxide is 
allowed to adhere to a glass tube, it cannot be freely after-processed, 
and handling is restricted. 
Japanese Patent Kokai No. 3-75062 discloses a process for making a 
photoreactive semiconductor-supporting sheet which comprises supporting 
the photoreactive semiconductor on a specific latex. There is also the 
problem that the photoreactive semiconductor is buried in the latex film, 
and the effective surface area of the photoreactive semiconductor 
decreases. Furthermore, Japanese Patent Kokai No. 4-256755 discloses a 
method of supporting a photoreactive semiconductor on a particulate pulp 
having uneven surface and having a particle size of about 1 to 30 mm. In 
order to prevent the photoreactive semiconductor from falling off from the 
particulate pulp, a metal alkoxide and a latex are used in combination, 
and the effective surface area of the photoreactive semiconductor also 
decreases. 
For firmly supporting a photoreactive semiconductor, Japanese Patent Kokai 
No. 3-94814 discloses a method of deodorization using a corrugated sheet 
prepared by impregnating a corrugated ceramic paper with a titania sol 
and, then, firing the paper to support titanium oxide on the paper. 
Japanese Patent Kokai No. 5-253544 also discloses a method of supporting 
on an inorganic carrier by sintering. These methods can firmly support the 
photoreactive semiconductors on carriers, but there are still problems 
that titanium oxide sometimes granulates depending on the firing time to 
decrease the effective surface area and that photoreactive semiconductors 
buried in inorganic carriers such as ceramic paper cannot effectively act 
and, besides, the photoreactive semiconductors cannot be sufficiently 
supported in such an amount as they can act effectively. 
The usefulness of photoreactive semiconductors includes not only the 
above-mentioned removal of noxious gases, but also photobactericidal 
action. This is discussed in Collection of Chemical Engineering Articles, 
Vol. 19, No. 6, Page 1149, edited by Chemical Engineering Association. In 
the article, titanium oxide is used in the form of suspension as in the 
case of Cundall et al. Killing of bacteria by photobactericidal action of 
photoreactive semiconductors is applicable not only to purification of, 
for example, bath and swimming pool, but also to sterilization of drinking 
water. Considering that removal of organic matters in water can be 
utilized for treatment of industrial waste liquors, photoreactive 
semiconductors can be considered to have a considerably wide field of 
application, but when they are used in the form of a suspension, there is 
a serious problem that the treated waste liquor and the photoreactive 
semiconductor must be separated. 
SUMMARY OF THE INVENTION 
The present invention relates to a photoreactive noxious substance purging 
agent capable of decomposing noxious substances in air and water such as 
malodor or bacteria utilizing a photocatalytic decomposition action of 
photoreactive semiconductors and to a photoreactive noxious substance 
purging material using the said removing agent, and the object of the 
present invention is to provide a photoreactive noxious substance purging 
agent in which loss of effective surface area of photoreactive 
semiconductor can be held down to the minimum and noxious substance 
removing ability can be effectively brought out and which can 
satisfactorily hold a powder of photoreactive semiconductor or the like 
and can be handled without causing liberation of the photoreactive 
semiconductor even in water, and to further provide a photoreactive 
noxious substance purging material using said removing agent. Furthermore, 
the present invention provides a photoreactive noxious substance purging 
material comprising a base to which various properties such as flame 
retardancy, strength and hand are given so that it can be handled in 
various forms by improving handleability and post-processability of the 
photoreactive noxious substance purging agent. 
The inventors have conducted intensive research in an attempt to solve the 
above problems and have found that loss of the effective surface area for 
photoreaction of the photoreactive semiconductor can be held down to the 
minimum and the noxious substance removing ability can be effectively 
brought out when the photoreactive noxious substance purging agent is 
composed of a photoreactive semiconductor, a carrier and a 
microfibrillated microfiber. 
When this photoreactive noxious substance purging agent is enclosed between 
sheets, at least one of which is gas permeable, there can be obtained a 
photoreactive noxious substance purging material having excellent strength 
in which the photoreactive noxious substance purging agent can be not only 
spread and held in a large area, but also processed into optional shapes, 
and, furthermore, the photoreactive noxious substance purging agent is not 
liberated even if it is used in water. Moreover, when a flame-retardant 
nonwoven fabric is used as the gas-permeable sheet, flame retardance of 
the whole removing material can be attained since the photoreactive 
semiconductor and the carrier which are main components of the removing 
material are per se incombustible, and, in addition, flexibility and hand 
of the photoreactive noxious substance purging material can be adjusted. 
On the other hand, when the photoreactive semiconductor, the carrier and 
the microfibrillated microfiber are enclosed between two or more sheets, 
at least one of which has gas permeability and, in some case, has flame 
retardancy, if a thermoplastic resin is used together with these 
enclosures such as the photoreactive semiconductor, the thermoplastic 
resin acts as a binder to improve adhesion between the sheets, and there 
can be obtained a photoreactive noxious substance purging material having 
excellent strength in which the photoreactive noxious substance purging 
agent is not liberated even if the material is used in water. 
Furthermore, as for the form of the photoreactive noxious substance purging 
material containing the photoreactive noxious substance purging agent 
comprising the photoreactive semiconductor, the carrier and the 
microfibrillated microfiber in the present invention, in addition to the 
above-mentioned type of the photoreactive noxious substance purging agent 
being enclosed between the sheets, there may be employed a photoreactive 
noxious substance purging agent-coated (laminate) type formed by coating 
an aqueous liquid of a composite flocculate comprising at least a 
photoreactive semiconductor, a carrier and a microfibrillated microfiber 
on a support comprising at least a thermoplastic resin. 
Furthermore, there may be formed a photoreactive noxious substance purging 
material in the form of a sheet of the photoreactive noxious substance 
purging agent (self-contained type) prepared by mixing the aqueous liquid 
of a composite flocculate comprising at least a photoreactive 
semiconductor, a carrier and a microfibrillated microfiber with a 
dispersion of a fibrous thermoplastic resin which substantially 
constitutes the support and subjecting the mixture to wet paper making 
process to form a sheet. Moreover, the aqueous liquid of composite 
flocculate is mixed with an aqueous dispersion containing at least one of 
inorganic fiber and aramid fiber, the mixture is subjected to wet paper 
making process to form a wet paper, two or more of the resulting wet 
papers are laminated, heated and pressed to integrate them, and, thus, the 
photoreactive noxious substance purging material in the form of a board 
can be obtained.

DETAILED DESCRIPTION OF THE INVENTION 
The photoreactive noxious substance purging agent of the present invention, 
and constructive elements of the photoreactive noxious substance purging 
material comprising said removing agent, and a method for producing the 
same will be explained in detail below. The photoreactive semiconductors 
used in the present invention are semiconductors which induce a 
photocatalytic reaction and have a width of forbidden band of 0.5-5 eV, 
preferably 1-4 eV. As examples of these photoreactive semiconductors used 
in the present invention, mention may be made of particles of metal oxides 
such as zinc oxide, tungsten oxide, titanium oxide, cerium oxide, etc. 
Among them, titanium oxide is most suitable for use in life space from the 
points of structural stability, photoreactive noxious substance removing 
ability and safety in handling, and can be advantageously used as the 
photoreactive semiconductors in the present invention. 
The titanium oxides advantageously usable as the photoreactive 
semiconductors include, in addition to general-purpose titanium dioxide 
used as white pigments, titanium oxides and hydroxides such as metatitanic 
acid, orthotitanic acid, hydrous titanium oxide, hydrated titanium oxide 
and titanium hydroxide. These titanium oxides may be surface-treated with 
metals such as Pt, Au, Ag, Cu, Pd, Ni, Rh, Nb, Sn and Ru, and metal oxides 
such as ruthenium oxide and nickel oxide. 
The noxious substance decomposing mechanism of the photoreactive 
semiconductor is as follows: When the photoreactive semiconductor receives 
an active light, free radicals are formed on the surface and they attack 
the noxious substance which contacts with the photoreactive semiconductor 
to decompose the noxious substance. In order to sufficiently exhibit this 
process, it is effective to increase the specific surface area of the 
photoreactive semiconductor, thereby to increase the free 
radical-producing points. In addition, when the specific surface area is 
increased, contact area with the noxious substance per unit amount also 
increases, and, hence, the larger specific surface area is effective to 
decompose the noxious substance. 
However, when it is attempted to increase the specific surface area of the 
photoreactive semiconductor, stability in the production of photoreactive 
semiconductor decreases and it becomes difficult to obtain reproducible 
properties. Thus, the specific surface area of the photoreactive 
semiconductor of the present invention is preferably about 10-500 m.sup.2 
/g, more preferably about 100-500 m.sup.2 /g. Especially, in the case of 
titanium oxide, the specific surface area is preferably about 50-400 
m.sup.2 /g, more preferably about 100-400 m.sup.2 /g. Furthermore, the 
particle size of the photoreactive semiconductor is preferably about 3-120 
nm, more preferably about 3-20 nm. 
Content of the photoreactive semiconductor in the photoreactive noxious 
substance purging material is preferably 1-50 g/m.sup.2, more preferably 
2-30 g/m.sup.2. If the content is lower than 1 g/m.sup.2, the effect of 
decomposing the noxious substance cannot substantially be expected and if 
it is higher than 50 g/m.sup.2, the photoreactive semiconductor cannot be 
firmly held in the matrix of the photoreactive noxious substance purging 
material to cause leakage of the photoreactive semiconductor. Since with 
increase in the absolute amount of the photoreactive semiconductor, the 
higher effect of decomposing the noxious substance can be expected, and, 
therefore, it is desired to increase the content of the photoreactive 
semiconductor within the range where handleability and other 
characteristics are satisfied. 
Since the photoreactive semiconductors having a large specific surface area 
which are used preferably in the present invention are very small in 
particle size as mentioned above, and are poor in film-formability when 
used singly, the photoreactive semiconductors held in the matrix of 
photoreactive noxious substance purging material fall off shortly and 
cannot be used stably at least in water. Therefore, a carrier is used in 
combination with the photoreactive semiconductor to form larger particles, 
whereby leakage of the photoreactive semiconductor at the time of 
preparation and use can be prevented and deactivation of active points on 
the surface of the photoreactive semiconductor can be considerably 
inhibited as compared with the flocculate of single photoreactive 
semiconductor. 
Examples of the carrier used in the present invention are silica, alumina, 
zirconia, activated clay, zeolite, sepiolite, halloysite, hydroapatite, 
zinc oxide, silica-alumina composites, silica-zinc oxide composites, 
silica-magnesia composites, zinc oxide-magnesia composites, 
silica-alumina-zinc oxide composites, silica-alumina-magnesia composites, 
and active carbons prepared from various materials such as wood chips and 
coconut shell. 
When the carriers per se have adsorptivity, such as activated clay, 
zeolite, sepiolite and active carbons, the photoreactive semiconductors 
are not needed to be supported on all of the carriers, and those which 
have the photoreactive semiconductors supported and those which have no 
semiconductors supported may be used together or separately. In the case 
of ferrous metal compounds which per se have catalytic action, such as 
iron sesquioxide, the photoreactive semiconductors may be supported 
thereon or they may be mixed with carrier particles having the 
photoreactive semiconductors supported thereon. Moreover, some carriers 
preferentially adsorb those substances having specific chemical or 
physical characteristics such as acidic substances and basic substances. 
Therefore, it is preferred to select optimum species from a group of 
carriers depending on conditions of use, and, in some cases, they may be 
used in combination. 
The carriers used in the present invention have a specific surface area of 
preferably about 50-2000 m.sup.2 /g, and in the case of active carbon, the 
specific surface area is preferably 500-1500 m.sup.2 /g. The particle size 
of the carriers is preferably at least about 10 times that of the 
photoreactive semiconductors used together. The particle size of the 
carriers is preferably 100 nm-50 .mu.m, and in the case of active carbon, 
it is 50 nm-10 .mu.m. The carriers may be used in the form of particles, 
but especially, in the case of enclosing them between gas-permeable 
sheets, they may be in the form of pellets or tablets prepared by molding 
the particles. 
Content of the carrier in the photoreactive noxious substance purging 
material of the present invention is determined by mixing ratio of the 
photoreactive semiconductor and the carrier. That is, the mixing weight 
ratio of the photoreactive semiconductor and the carrier is preferably 
about 1:30-10:1, more preferably about 1:10-5:1. With the absolute amount 
of the photoreactive semiconductor being fixed, if the mixing ratio of the 
carrier to the photoreactive semiconductor is too high, content of the 
carrier in the photoreactive noxious substance purging material is high 
and it is difficult to hold the carrier in the matrix of the photoreactive 
noxious substance purging material. On the other hand, if the mixing ratio 
is too low, the photoreactive semiconductor agglomerates, resulting in 
deterioration of noxious substance removing ability and, besides, causing 
falling off of powder with lapse of time. 
In the present invention, if necessary, a microfibrillated microfiber is 
used together with the photoreactive semiconductor and the carrier. The 
microfibrillated microfiber used in the present invention can be obtained 
by various processes such as those enumerated below. 
(1) A process of dropping a synthetic polymer liquid into a solvent which 
is a poor solvent for the polymer under application of shearing force to 
precipitate a fibrous fibril (Fibrid process, Japanese Patent Kokoku No. 
35-11851). 
(2) A process of polymerizing a synthetic monomer under application of 
shearing to precipitate a fibril (Polymerization shearing process, 
Japanese Patent Kokoku No. 47-21898). 
(3) A process of mixing two or more incompatible polymers, melt-extruding 
or spinning the mixture, followed by cutting and fibrillating into fibers 
by a mechanical means (Split process, Japanese Patent Kokoku No. 35-9651). 
(4) A process of blending two or more incompatible polymers, melt-extruding 
or spinning the blend, followed by cutting, immersing in a solvent to 
dissolve one of the polymers and fibrillating into fibers (Polymer blend 
dissolving process, U.S. Pat. No. 3,382,305). 
(5) A process of explosively jetting a synthetic polymer from high-pressure 
side into low-pressure side at a temperature higher than the boiling point 
of solvent and then, fibrillating into fibers (Flush spinning process, 
Japanese Patent Kokoku No. 36-16460). 
(6) A process of blending a polyester polymer with an alkali-soluble 
component incompatible with the polymer, molding the blend, and then 
subjecting the molded product to a weight reduction processing with an 
alkali, followed by beating and fibrillating into fibers (Alkali weight 
reduction and beating process, Japanese patent Kokai No. 56-315). 
(7) A process of cutting a highly crystalline and highly orientated fiber 
such as cellulose fiber or Kevlar fiber into a suitable fiber length, 
dispersing the fibers in water, and fibrillating them by a homogenizer, 
beating machine, sand mill, etc. (Japanese Patent Kokai Nos. 56-100801 and 
59-92011 and U.S. Pat. No. 4,761,203). 
Examples of the microfibrillated microfibers used in the present invention 
are cellulose fibers fibrillated by a homogenizer (CELLISH KY-100S and 
CELLISH KY-110S), similarly fibrillated aramid fibers (CELLISH KY-400S), 
similarly fibrillated acrylic fibers (CELLISH KY-410S), similarly 
fibrillated polyethylene fibers (CELLISH KY-420S), similarly fibrillated 
polypropylene fibers (CELLISH KY-430S) (these are manufactured by Daicel 
Ltd.), fibril fibers comprising an acrylonitrile homopolymer (CASHMILON 
FCA manufactured by Asahi Kasei Kogyo K.K.) beaten by a refiner, etc., and 
polyester pulps obtained by the alkali weight reduction beating process. 
Bacteria cellulose defibrated products may also be used as the 
microfibrillated microfibers. The bacteria cellulose defibrated products 
include those which are obtained by mechanically splitting celluloses 
produced by microorganisms, those containing hetero polysaccharides having 
a main chain of cellulose, and those containing glucans such as .beta.-1,3 
and .beta.-1,2. These are described in detail in Japanese Patent Kokoku 
No. 6-72394, etc. 
The diameter of the microfibrillated microfibers can be adjusted from the 
order of submicron to the order of micron or more depending on the 
fibrillation conditions including shearing, beating, splitting, etc. when 
the microfiber is incorporated in the course of supporting the 
photoreactive semiconductor on the carrier having a particle diameter 
equal to or larger than that of the microfiber, in order to form large and 
stable flocks by strong interaction, the preferred microfiber is at least 
partially, more preferably wholly fibrillated to 1 .mu.m or less. 
As mentioned above, the microfibrillated microfibers used in the present 
invention have very fine diameter as compared with usual fibers. 
Therefore, they have a high specific surface area and there are much more 
polar functional groups resulting from the fibers, and, as a result, the 
adsorptivity is markedly increased. Accordingly, such microfibrillated 
microfibers have the effect of firmly binding the photoreactive 
semiconductor and the carrier or the photoreactive semiconductors with 
each other or the carriers with each other without greatly covering the 
surface of the particles by fibrillation and with use of them in a small 
amount. Furthermore, once they interact with the particles, the 
interaction does not substantially decrease even when introduced into 
water. 
Content of the microfibrillated microfiber used in the present invention is 
determined by the mixing ratio of the photoreactive semiconductor and the 
carrier and the microfibrillated microfiber. That is, the amount of the 
microfibrillated microfiber based on the total amount of the photoreactive 
semiconductor and the carrier is preferably about 0.2-50% by weight, more 
preferably 0.5-10% by weight. Although the microfibrillated microfiber has 
the effect to hold the photoreactive semiconductor in the matrix of the 
removing material, when the microfiber directly contacts with the 
photoreactive semiconductor, it undergoes deterioration due to 
decomposition. Therefore, it is preferred to use the microfiber in the 
minimum amount in which the photoreactive semiconductor and/or the carrier 
do not fall off from the photoreactive noxious substance purging material. 
Among the above-mentioned microfibrillated microfibers, the bacteria 
cellulose defibrated products are split most uniformly and are the highest 
in the holding amount per unit amount of the microfiber. However, 
cellulose fibers including the bacteria cellulose defibrated products more 
readily undergo deterioration by the photoreactive semiconductor than 
aramid fibers, etc., and the shape of the photoreactive noxious substance 
purging material cannot be continually retained. Therefore, cellulosic 
microfibrillated microfibers may be used when the period of service of the 
photoreactive noxious substance purging material is limited, for example, 
when they are used for filters which are replaced after a certain period 
irrespective of occurrence of deterioration, but aramid microfibrillated 
microfibers are suitable when the removing material is used for the longer 
period or when the higher flame retardancy is required. 
As the method for producing the photoreactive noxious substance purging 
agent using the above-mentioned constructive elements, mention may be made 
of, for example, a method of first mixing the photoreactive semiconductor 
with the carrier, then mixing therewith the microfibrillated microfiber, 
and flocculating and granulating the photoreactive 
semiconductor-supporting carriers and a method of simultaneously mixing 
the three elements and accelerating the supporting of the photoreactive 
semiconductor onto the carriers in addition to mixing of the carriers per 
se. In both the former and latter methods, the photoreactive noxious 
substance purging agents are obtained by carrying out the mixing in a 
dispersion medium mainly composed of water, if necessary, together with 
known surface active agents and flocculants. Especially, the supporting 
step in the former method may be carried out by dry-mixing using. Henschel 
mixer, etc. 
The resulting photoreactive noxious substance purging agent may be dried 
and utilized as a remover of malodor and others. In the case of this 
photoreactive noxious substance purging agent, particles of the composite 
can be enlarged without damaging not so much the noxious substance 
removing ability originally possessed by the photoreactive semiconductor 
as compared with a mixed powder prepared by merely dry mixing the three 
components, and the photoreactive semiconductor is not liberated not only 
in air, but also in water even in the form of granules and the removing 
agent can be used satisfactorily in any forms. 
According to the present invention, the photoreactive noxious substance 
purging material is produced by enclosing the photoreactive noxious 
substance purging agent obtained above between two or more sheets, at 
least one of which has gas permeability (including the embodiment of 
folding one sheet in two and enclosing the removing agent therebetween). 
As the sheets between which the removing agent is enclosed, only one side 
of the sheet or only one of the sheets may have gas permeability or both 
sides or all of the sheets may have gas permeability. In order to 
effectively exhibiting the noxious substance removing ability of the 
photoreactive semiconductor, it is further preferred that at least one of 
the sheets have light transmission properties. 
The gas permeability of the sheet used in the present invention can be 
measured by the gas permeability test method A specified in JIS L1096. The 
gas permeability of the sheet is preferably 5-150 cm.sup.3 /cm.sup.2 
.multidot.S, more preferably 10-100 cm.sup.3 /cm.sup.2 .multidot.S 
measured by JIS L1096. If the gas permeability is less than 5 cm.sup.3 
/cm.sup.2 .multidot.S, since the gas permeability of the sheet is 
insufficient, noxious substance cannot sufficiently reach the 
photoreactive semiconductor enclosed in the sheets and the inherent 
noxious substance removing ability cannot be exhibited. On the other hand, 
if the gas permeability is more than 150 cm.sup.3 /cm.sup.2 .multidot.S, 
the gas permeability is good, but void diameter of the sheets is great and 
the photoreactive semiconductor and the carrier between the sheets are 
likely to fall off although the noxious substance sufficiently flows into 
the sheets. Therefore, at least one of the sheets enclosing the 
photoreactive noxious substance purging agent of the present invention has 
the gas permeability within the above range. 
As the sheets which enclose the photoreactive noxious substance purging 
agent, mention may be made of, for example, woven fabric, nonwoven fabric, 
net, and sponge, and, furthermore, general-purpose thermoplastic films or 
thin sheets such as polyethylene film, polypropylene film and polyester 
film. Among them, the films or thin sheets which are poor in gas 
permeability may be improved in gas permeability by making fine holes 
therethrough. As mentioned above, removal of noxious substance with the 
photoreactive semiconductor requires not only contacting of the 
photoreactive semiconductor with the noxious substance, but also exposing 
of the photoreactive semiconductor to active light. Therefore, at least 
one of the sheets requires to have also light transmission properties. 
Particularly, when a nonwoven fabric is used as the sheets enclosing the 
photoreactive noxious substance purging agent of the present invention, 
not only a gas permeability and light transmission of a certain degree can 
be secured, but also processing for enclosing the removing agent and 
processing of the photoreactive noxious substance purging material after 
formed can be easily performed. 
As the fibers used for the nonwoven fabrics advantageously usable as the 
sheets for enclosing the photoreactive noxious substance purging agent, 
mention may be made of, for example, the fibers of olefins such as 
polyethylene and polypropylene, polyesters such as Dacron, polyamides such 
as polyvinyl acetate, styrenevinyl acetate copolymer and nylon, acrylics 
such as polyacrylonitrile, Acrilan, Orlon, Dynel and Verel, polyvinyl 
chloride, polyvinylidene chloride, polystyrene, polyvinyl ether, polyvinyl 
ketone, polyether, polyvinyl alcohols, dienes, and polyurethanes. Shape of 
these fibers is not limited, and they may have not only the nearly 
circular cross-section, but also so-called modified cross-sections such as 
oval, triangle, star, T-shape, Y-shape and leaf-shape. In addition, they 
may have voids on the surface or may have a branched structure. 
Furthermore, fibers having a sheath-core structure are also preferred in 
that inter-fiber bond strength and stiffness of nonwoven fabric made 
therefrom can be suitably controlled. The fibers having sheath-core 
structure include those which comprise a core portion of polyester and a 
sheath portion of a polyester copolymer or a core portion of polyester and 
a sheath portion of polyolefin. The feature of the sheath-core structure 
resides in that the core portion and the sheath portion differ in 
softening point. The core portion preferably has a softening point of 
higher than about 230.degree. C. because the shape of the fibers must be 
maintained at the time of heat treatment in processing, and the sheath 
portion preferably has a softening point of about 90.degree.-120.degree. 
C. because the fibers per se must heat adhere to each other to form a 
sufficient bond. When such fibers of sheath-core structure are used, 
strength can be held without conducting a high-temperature heat treatment. 
In addition to the constructive elements mentioned above, as the components 
constituting the sheet of the present invention, mention may be made of 
natural fibers such as wood pulp, hemp pulp, esparto, and cotton fibers, 
regenerated fibers and semisynthetic fibers such as rayon fibers and 
acetate fibers, and inorganic fibers such as glass fibers and alumina 
fibers. It is preferred to use these fibers in such an amount as not 
deteriorating the characteristics such as strength and gas permeability 
possessed by nonwoven fabrics formed of only the aforementioned 
thermoplastic fibers. 
When the photoreactive noxious substance purging materials of the present 
invention are used for removal of noxious substances in the life space by 
using them for wall materials, ceiling materials, wall papers, curtains, 
etc., at least the sheet used for the photoreactive noxious substance 
purging material is desirably flame retardant. The fibers used for the 
nonwoven fabric sheet having flame retardancy include aramid fibers whose 
molecules per se are substantially frame retardant, substantially 
non-combustible inorganic fibers such as metal fibers, ceramic fibers, 
rock wool fibers, glass fibers, alumina fibers, zirconia fibers, silicon 
nitride fibers, silicon carbide fibers, and carbon fibers, and, 
furthermore, general-purpose fibers containing flame retardants chemically 
incorporated therein or physically blended therewith. In addition, there 
may also be used nonwoven fabrics composed of general-purpose fibers and 
treated with flame retardants. Among them, from the points of 
processability and cost of materials, preferred are nonwoven fabrics 
constituted of general-purpose fibers such as polyester, polyolefin, acryl 
and rayon fibers containing known phosphorus, halogen and inorganic flame 
retardants chemically incorporated therein or physically blended 
therewith, and nonwoven fabrics composed of general-purpose fibers and 
treated with flame retardants. 
In order to impart frame retardancy to the photoreactive noxious substance 
purging materials, not only the sheets which enclose the photoreactive 
noxious substance purging agent must be flame retardant, but also it is 
desired that the photoreactive noxious substance purging agent which is 
enclosed be also flame retardant. As the components of the photoreactive 
noxious substance purging agent, since the photoreactive semiconductor and 
the carrier are inorganic material and essentially flame retardant, it is 
desired that the microfibrillated microfibers be also flame retardant. 
Therefore, as the microfibrillated microfibers used for the photoreactive 
noxious substance purging agent enclosed with flame retardant nonwoven 
fabric, it is necessary to use microfibrillated aramid fibers such as 
Kevlar which are flame retardant materials or to use the microfibrillated 
microfibers treated with flame retardants before or after the 
microfibrillation treatment as mentioned above. 
Moreover, active carbon fibers are also suitable as the fibers which 
constitute the sheets used in the present invention. Active carbon fibers 
have an adsorption rate of 100-1000 times that of general powdery active 
carbon and have an adsorption amount of about 10 times per unit amount 
that of the general powdery active carbon. In addition, since the active 
carbon fibers are formed by firing starting fibers and are essentially 
non-combustible, they can also be advantageously used for imparting flame 
retardancy to the photoreactive noxious substance purging material. Active 
carbon fibers preferably usable in the present invention have a fiber 
length of about 0.5-50 mm and a fiber diameter of about 1-100 .mu.m, 
especially about 10 .mu.m. 
The nonwoven fabric used for the photoreactive noxious substance purging 
materials of the present invention is produced, for example, by a wet 
method comprising suspending the fibers in water and forming the 
suspension into a sheet by wet paper making process, so-called dry methods 
called resin-bonding method by adhesion of the fibers with resins, 
needle-punching by utilizing entanglement of the fibers with needle, 
stitch-bonding by knitting yarns, and thermal-bonding by bonding the 
fibers with heat, jet-bonding by entangling the fibers by jetting a highly 
pressurized water from a nozzle, spun-bonding by sheeting under direct 
spinning, and melt-blowing by sheeting with preparing fibrillated 
microfibers using the spraying principle at the time of direct spinning. 
By suitably selecting these production methods, not only the physical 
properties relating to mainly gas permeability such as thickness, void, 
shape of void and pore diameter of the resulting nonwoven fabric, but also 
the properties relating to mainly texture such as flexibility, elasticity 
and hairiness can be changed. Among these production methods, the 
spun-bonding and jet-bonding are preferred for obtaining a suitable 
strength. 
In order to impart a suitable mechanical strength to the nonwoven fabric 
used for the photo-reactive noxious substance purging material of the 
present invention, it is preferred to subject the nonwoven fabric to 
three-dimensional entangling treatment. The three-dimensional entangling 
treatment is a method which comprises putting a single nonwoven fabric or 
a laminate of a plurality of the nonwoven fabrics on a support and 
subjecting the nonwoven fabric to a mechanical treatment to 
three-dimensionally entangle the fibers. The method includes specifically 
needle-punching method and water jet entangling method, and the water jet 
entangling method is preferred since the entanglement can be performed 
uniformly and the production speed is high. The water jet entangling 
method is a method of jetting water onto the nonwoven fabric from above to 
three-dimensionally entangle the fibers constituting the nonwoven fabric, 
thereby to develop strength. 
As a condition to perform the three-dimensional entanglement strongly and 
properly, the diameter of a nozzle for jetting water is preferably 10-500 
.mu.m. The spacing between the nozzles is preferably 10-1500 .mu.m. The 
shape of the nozzle is preferably circular and is preferably such that a 
columnar water can be jetted. The support on which the nonwoven fabric is 
placed is preferably porous and has a porosity of preferably about 50-200 
mesh. The nozzles are required to have a range covering the width of the 
sheet to be processed in the direction perpendicular to the fabric making 
direction, and, on the other hand, in the fabric making direction, the 
number of nozzle heads can be changed within the range where sufficient 
entanglement can be obtained, taking into consideration the kind of 
nonwoven fabric, the weight per unit area, the processing speed and the 
water pressure. The processing speed is preferably in the range of 5-200 
m/min. The water pressure is preferably in the range of 10-250 
kg/cm.sup.2, more preferably in the range of 50-250 kg/cm.sup.2. 
In addition to these conditions, the surface properties can be improved by 
successively raising the water pressure from the beginning of the 
processing to the end of the processing, successively reducing the 
diameter of the nozzles and the spacing between the nozzles, rotating the 
nozzle head, vibrating the support from side to side, sprinkling water by 
inserting a wire between the nozzle and the web, or using a fan-shaped 
water flow. The three-dimensional entangling can be carried out not only 
on one side, but also on both sides. Moreover, after performing the 
entanglement, a nonwoven fabric may be further laminated thereon and 
subjected to entanglement. 
Thickness, etc. of the nonwoven fabric used as the sheets to enclose the 
photoreactive noxious substance purging agent of the present invention are 
not limitative, but fiber diameter is preferably in the range of 1-50 
.mu.m and basis weight is preferably in the range of 20-100 g/m.sup.2. 
When the fiber diameter is less than 1 .mu.m, voids become small and, 
thus, the gas permeability is poor, and when it is more than 50 .mu.m, the 
gas permeability is high, but the voids of the gas permeable sheet are 
large and the enclosed carrier and/or photoreactive semiconductor are apt 
to fall off. When the basis weight is smaller than 20 g/m.sup.2, the 
enclosures are apt to fall off and, besides, strength of the nonwoven 
fabric is insufficient to cause breakage at the time of processing or 
using. When it is greater than 100 g/m.sup.2, the gas permeability 
decreases or the voids become greater for securing the gas permeability to 
cause falling off of the enclosures. 
The photoreactive noxious substance purging material of the present 
invention is obtained by enclosing the photoreactive noxious substance 
purging agent between two or more sheets including nonwoven fabrics, at 
least one of which has gas permeability. In this case, a thermoplastic 
resin having heat adhesiveness may be used in the enclosure. When the 
thermoplastic resin is used, the sheets can be firmly bonded by heat 
melting the thermoplastic resin, and, furthermore, much more enclosures 
can be enclosed between the sheets. This is very effective. 
The thermoplastic resins used in the present invention are those which melt 
upon heating to develop the bonding effect between the gas-permeable 
sheets. As examples of the resins, mention may be made of ethylene-vinyl 
acetate copolymers or modified products thereof, ethylene-acrylate 
copolymers, ionomers, polyamides, nylons, polyesters, polyethylenes, 
polypropylenes, vinyl acetate copolymers, cellulose derivatives such as 
cellulose triacetate, polymethacrylate esters, polyvinyl ethers, 
polyurethanes, and polycarbonates. These resins are described in Hiroshi 
Fukada, "Practice of got Melt Adhesion", published from Kobunshi Kankokai 
in 1979. 
These thermoplastic resins are preferably molten only at the portions of 
the sheets to be bonded in order to improve adhesion between the sheets. 
By using them in this way, substantial decrease of the effective surface 
area of the enclosed photoreactive semiconductor can be inhibited. The 
thermoplastic resins are preferably used in the case of the total amount 
of the enclosures such as the photoreactive semiconductor excluding the 
thermoplastic resin being 20 g/m.sup.2 or more, and are used in an amount 
of preferably 1-30 parts by weight, more preferably 2-20 parts by weight 
on the basis of 100 parts by weight of the enclusures such as the 
photoreactive semiconductor excluding the thermoplastic resin. 
The photoreactive noxious substance purging agent, if necessary, together 
with the thermoplastic resin can be enclosed between the sheets by 
spreading the enclosures all over the sheet and covering them with another 
sheet, followed by bonding the sheets. Furthermore, at least one of the 
sheets may be processed to form uneven surface such as corrugated or baggy 
surface, the enclosures may be filled in the dented portions (protruded 
downwardly), and another sheet may be placed thereon to bond to each other 
at the protruded portions. When one of the sheets has the higher gas 
permeability and another has the higher light transmittance, the noxious 
substance capturing ability can be secured by using an adsorbent as the 
carrier, and, therefore, it is preferred to use the sheet of higher light 
transmittance as the uneven sheet so that the active light can be applied 
to the larger area of the photoreactive semiconductor. 
The method of carrying out the bonding between the sheets includes, for 
example, bonding with an adhesive, heat melt bonding by hot press, hot 
embossing roll, etc., and stitching. Two or more of these bonding methods 
may be used for different portions. Moreover, the heat melt bonded portion 
or the portion bonded with adhesive may be stitched or the portion 
stitched with a plastic fiber may be heat melt bonded. That is, the same 
portion may be bonded by two or more methods. 
The interval between the bonded meshes is preferably about 1-50 mm. The 
meshes may have various shapes such as tetragon, triangle, circle, oval 
and combination thereof. The gas permeability per unit area can be more 
highly secured and the noxious substance removing efficiency becomes 
higher with the narrower width of the bonded portion, but a certain width 
is necessary considering the processings such as cutting. The width of the 
bonded portion is preferably about 0.1-50 mm, especially preferably 0.5-5 
mm. If necessary, wide bonded portions may be provided at certain 
intervals. By these methods, the enclosures can be enclosed with securing 
the gas permeability. Even if the bonded portions at peripheral part are 
broken, falling off of the enclosure can be restrained to the minimum, 
and, furthermore, the removing material can be used in an optional size by 
cutting the bonded portions. 
The photoreactive noxious substance purging materials of the present 
invention can also be obtained by laminating the photoreactive noxious 
substance purging agents on a support or by mixing a component forming a 
support with the photoreactive noxious substance purging agent and forming 
a sheet containing the photoreactive noxious substance purging agent from 
the mixture in addition to the above-mentioned method of enclosing the 
photoreactive semiconductor and others between two or more sheets. 
In the present invention, for laminating the photoreactive noxious 
substance purging agents on a support, first the photoreactive 
semiconductor, the carrier and the microfibrillated microfiber are 
dispersed together or separately in an aqueous liquid mainly composed of 
water. When these three components are simultaneously dispersed, the 
previously mixed three components may be simultaneously dispersed in the 
aqueous liquid under stirring. More preferably, first the carrier is 
dispersed and the photoreactive semiconductor is scattered and introduced 
into the dispersion to adsorb and support the photoreactive semiconductor 
onto the carrier. Then, to this liquid is added the microfibrillated 
microfiber to form a composite flocculate. In this case, the 
micro-fibrillated microfiber is preferably previously dispersed in the 
aqueous liquid. 
An aqueous dispersion of the composite flocculate can be prepared by mere 
mixing, but the flocculation state may be adjusted using a suitable 
flocculant. The flocculants used in the present invention include, for 
example, basic hydroxides such as zinc hydroxide, aluminum hydroxide, 
barium hydroxide and magnesium hydroxide, inorganic hydrous oxides such as 
alumina, silica and zirconia, aluminum sulfate, polyaluminum chloride, 
anion- or cation-modified polyacrylamides, acrylic acid or methacrylic 
acid-containing copolymers, alginic acid and polyvinylphosphoric acid, and 
alkaline salts thereof, and acryloyl-morpholine polymers. These 
flocculants may be used each alone or in combination of two or more. 
The flocculant may be added to the dispersion of the previously mixed three 
components with stirring. Alternatively, it may be added to the dispersion 
of the photoreactive semiconductor to previously flocculate the 
photoreactive semiconductor and, then, other components may be added 
simultaneously or successively to form flocculates, or it may be added to 
the dispersion of the carrier to previously flocculate the carrier and, 
then, other components may be added simultaneously or successively to form 
flocculates. Since the size of the flocculates affects the degree of at 
least the photoreactive semiconductor being held in the photoreactive 
noxious substance purging material and uniformity and processability of 
the photoreactive noxious substance purging material, amount and method of 
addition must be optionally determined depending on the flocculants used. 
The thus prepared aqueous liquid of the composite flocculate is coated on a 
support to obtain the photoreactive noxious substance purging material. 
The shape of the support is unlimited as far as it is in the form of a 
sheet, and the support includes sheets which are previously melt-molded by 
extrusion method, inflation method, stretching method, etc. and nonwoven 
fabrics made by the above-mentioned methods for making nonwoven fabrics. 
Being different from the sheets used for enclosing method according to the 
present invention, the sheets used for the coating method may not have gas 
permeability, but they may naturally have gas permeability or light 
transmission. The material of these supports is also unlimited, but 
preferably they are mainly composed of at least thermoplastic resins in 
view of holding and after-processability of the photoreactive noxious 
substance purging agent. As the thermoplastic resins, there may be used 
the materials (fibers) which constitute the nonwoven fabrics used in the 
enclosing method. 
The composite flocculate comprising at least the photoreactive 
semiconductor, the carrier, the microfibrillated microfiber, and, 
optionally, the flocculant can be applied to the support, for example, by 
impregnation of the support with an aqueous liquid of the flocculate by 
dipping, and by coating the aqueous dispersion on the support by a coater. 
As the method of impregnation and coating, mention may be made of those 
which use conventional size press, gate roll size press, film transfer 
type size press, roll coater, air doctor coater, rod (bar) coater, blade 
coater, spray coater and curtain coater. 
Before application of the composite flocculate by impregnation or coating, 
the supports are preferably subjected to surface treatments such as glow 
discharge treatment, flame treatment, plasma treatment, electron ray 
irradiation treatment, ultraviolet irradiation treatment and ozone 
treatment. Two or more of these surface treatments may be carried out in 
combination and, furthermore, different treatments may be applied to one 
side and another side of the supports. Since the composite flocculate may 
be applied to only one side of the support, the surface treatment may be 
conducted on only the side to which the flocculate is to be applied. 
The photoreactive noxious substance purging material of the present 
invention can also be obtained by mixing the composite flocculate with a 
support-forming component and forming therefrom a sheet containing the 
photoreactive noxious substance purging agent. The support-forming 
component is a component necessary to retain the shape of the sheet of the 
photoreactive noxious substance purging material made from the aqueous 
dispersion of the composite flocculate. The support-forming component is 
preferably in the form of fiber, and the material of the fiber is 
preferably a thermoplastic resin from the points of support-formability 
and after-processability. 
As the thermoplastic resin fiber, there may be used all of the 
thermoplastic fibers which constitute the nonwoven fabrics used in the 
enclosing method. In order to improve strength of the photoreactive 
noxious substance purging materials, there may be further added a small 
amount of thermosetting synthetic resins such as aniline resin, alkyd 
resin, epoxy resin, urea resin, phenolic resin, unsaturated polyester 
resin, furan resin and melamine resin, vegetable fibers such as wood pulp, 
straw, kenaf, linter, bagasse and esparto, regenerated fibers such as 
rayon, semisynthetic fibers such as acetate, fluoroplastic fiber, silicone 
fiber, metal fiber, carbon fiber, ceramic fiber and various glass fibers. 
The above aqueous liquid of the composite flocculate is mixed with the 
support-forming components, and, if necessary, viscosity of the mixture is 
adjusted with addition of known viscosity modifier (thickening agent). 
Then, the mixture is made into a sheet by known wet paper making process 
by a cylinder paper machine, and the sheet is dried to obtain a 
photoreactive noxious substance purging material. The support-forming 
component may be added as it is to the aqueous liquid of the composite 
flocculate, but preferably it is dispersed in an aqueous liquid and the 
dispersion is mixed with the aqueous liquid of the composite flocculate. A 
surface active agent may be used in dispersing the support-forming 
component. 
In order to firmly hold the photoreactive semiconductor and others with the 
support-forming component, there may be further used a small amount of at 
least a self film-forming binder. Examples of the binders used in the 
present invention are starch, natural gums, chitosan, alginates, cellulose 
derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, 
polyvinyl acetate, polyvinyl alcohol, poly-N-vinylpyrrolidone, synthetic 
resin emulsions such as acrylic emulsion, styrenic emulsion, polyvinyl 
chloride emulsion and polyvinylidene chloride emulsion, and various 
latexes such as NBR and SBR. 
The thus produced photoreactive noxious substance purging material may be 
put together with a sheet which does not contain at least one of the 
photoreactive semiconductor, the carrier and the micro-fibrillated 
microfiber or a photoreactive noxious substance purging material having 
the same or different composition produced by the same or different method 
before the drying step, and they may be integrated with retaining 
entanglement of the fibers to form a sheet having a multilayer structure 
or a board imparted with a higher strength by further laminating the 
sheets. 
When the photoreactive noxious substance purging material is made into a 
board, since light or the noxious substance reaches only both the surface 
portion of the outermost layers, a sheet containing the photoreactive 
semiconductor is not needed to be laminated as an inner layer, but it 
serves to improve the strength of the photoreactive noxious substance 
purging material, and since main uses of the board-like photoreactive 
noxious substance purging material include structural materials, 
especially the support-forming component constituting the board-like 
photoreactive noxious substance purging material is preferably a flame 
retardant material. The flame retardant material as the support-forming 
component may be thermoplastic synthetic fiber, natural pulp or the like 
which is chemically or physically treated with flame retardants mentioned 
above, but preferred are aramid fibers made of essentially flame retardant 
materials and non-combustible inorganic fibers such as glass fiber, 
ceramic fiber, rock wool fiber, carbon fiber, zirconia fiber and alumina 
fiber. 
In order to produce a board-like photoreactive noxious substance purging 
material, the photoreactive semiconductor, the carrier, the 
microfibrillated microfiber and inorganic fiber or aramid fiber which is 
the support-forming component are successively or simultaneously added to 
water to disperse them in water, or each of them or some of them in groups 
are separately dispersed in water and the dispersions are mixed. In this 
case, since inorganic fibers are inferior in strength of entanglement 
thereof, when inorganic fibers are used as the support-forming component, 
it is preferred to use an inorganic adhesive. 
Examples of the inorganic adhesives used in producing the board are CaO, 
silica, alumina, phosphates, alkali metal silicates, quenched slag, fly 
ash, siliceous mixing agents such as diatomaceous earth, and mixtures 
thereof. Of these inorganic adhesives, suitable is a powder of Kosei clay 
occurring in Kosei Province of China. The clay is preferably dried at 
50.degree.-300.degree. C. and used in the form of a powder of 10-300 mesh. 
As for the amount of the inorganic adhesive for the inorganic fiber, when 
it is increased, the maintenance of the fiber is improved, but if it is 
too large, the characteristics as the board such as flexural strength and 
tensile strength deteriorate. Therefore, amount of the adhesive is 
preferably 20-100 parts by weight for 100 parts by weight of the inorganic 
fiber. 
The thus prepared aqueous slurry, if necessary, with addition of a 
viscosity modifier and a surface active agent, is made into a wet paper by 
conventional wet paper making process. Two or more of the wet papers 
depending on the desired thickness of the board are laminated, heated and 
pressed to integrate them, thereby to obtain the photoreactive noxious 
substance removing board. 
Furthermore, the photoreactive noxious substance purging material of the 
present invention may be put together with a sheet which does not contain 
at least one of the photoreactive semiconductor, the carrier and the 
microfibrillated microfiber or a photoreactive noxious substance purging 
material having the same or different composition produced by the same or 
different method after the drying step, and the two or more sheets may be 
melt bonded with heat or bonded with adhesives to form a composite. 
Moreover, the photoreactive noxious substance purging material may be put 
together with a film or sheet which does not contain at least the 
photoreactive semiconductor and which comprises natural fibers such as 
wood pulp, thermo-plastic resins, thermosetting resins, ceramics, metals 
or the like to form a composite having multilayer structure. In the case 
of such structure, not only printing or coloring for giving designs to the 
sheet can be conveniently carried out, but also textures such as touch can 
be improved by using a nonwoven fabric comprising rayon. 
The photoreactive noxious substance purging agent of the present invention 
comprises a photoreactive semiconductor, a carrier and a microfibrillated 
microfiber, and when the photoreactive semiconductor receives an active 
light, noxious substance can be decomposed by a photocatalytic 
decomposition action of the photoreactive semiconductor. Furthermore, by 
combining the photoreactive semiconductor with a carrier, the very fine 
photoreactive semiconductor is supported on the carrier to form large 
particles, and, as a result, not only the handleability is improved, but 
also, when the carrier has an adsorbing ability for noxious substances, 
noxious substances are adsorbed to the carrier and removed even when the 
photoreactive noxious substance purging agent is left at the places where 
no light is applied. When this photoreactive noxious substance purging 
agent which has adsorbed noxious substances is left at the places where 
light is applied, the noxious substances adsorbed to the carrier can be 
decomposed by the photoreactive semiconductor and adsorptivity of the 
carrier can be regenerated. 
Furthermore, in the matrix of the photoreactive noxious substance purging 
material of the present invention, the microfibrillated microfiber in a 
small amount has the effect to allow the photoreactive semiconductor and 
the carrier, the photoreactive semiconductors per se or the carriers per 
se to adhere to each other without greatly covering the surface of 
particles by fibrillation. Thus, not only the noxious substance 
removability can be effectively brought out, but also the powders such as 
the photoreactive semiconductor and others can be satisfactorily held and 
the photoreactive noxious substance purging agent can be handled without 
causing liberation of the photoreactive semiconductor even in water. 
By enclosing this photoreactive noxious substance purging agent between 
sheets at least one of which is gas permeable, not only the photoreactive 
semiconductor and others can be spread and held in a great area, but also 
when the sheets are bonded in the desired shape and the bonded portion is 
cut, processing in optional shapes can be performed, and a photoreactive 
noxious substance purging material which has an excellent strength and 
from which the photoreactive noxious substance purging agent does not fall 
off even when used in water can be obtained. Furthermore, flame retardancy 
can also be given to the photoreactive noxious substance purging material 
by using a flame retardant nonwoven fabric as the gas permeable sheet. 
Moreover, in the case of enclosing the photoreactive semiconductor, the 
carrier and the microfibrillated microfiber between two or more sheets at 
least one of which has gas permeability and, in some cases, additionally 
flame retardancy, when a thermoplastic resin is used together with the 
enclosures of photoreactive semiconductor, etc., the thermoplastic resin 
acts as a binder which improves the adhesion between the sheets and the 
photoreactive noxious substance purging material having the higher 
strength can be obtained, and, in addition, the enclosures such as the 
photoreactive semiconductor, etc. can be enclosed between the sheets in a 
greater amount. 
As for the form of the photoreactive noxious substance purging material, 
there is the following form in addition to the above-mentioned type of 
being enclosed between the sheets. That is, when an aqueous liquid of a 
composite flocculate comprising at least the photoreactive semiconductor, 
the carrier and the microfibrillated microfiber is applied to a support 
comprising at least a thermoplastic resin, since the photoreactive 
semiconductor is supported on at least one of the carrier and the 
microfiber and fixed on the support, the photoreactive semiconductor is 
exposed much more on the surface of the removing material, and thus, 
contact with noxious substances and receiving rate of active light are 
improved. 
Furthermore, when the aqueous liquid of composite flocculate is mixed with 
the thermoplastic resin fiber substantially constituting the support, and 
the mixture is made into a sheet by wet paper making process, the 
photoreactive semiconductor is firmly incorporated together with the 
carrier and the microfiber into the matrix of the support comprising the 
thermoplastic resin fiber and, moreover, uniformly dispersed in the 
surface portion of the sheet and can also uniformly response to light, 
resulting in less fluctuation in noxious substance removability. 
Furthermore, in the case of the photoreactive noxious substance purging 
material made by the composite flocculate coating method which uses the 
thermoplastic resin in the form of fiber as such or the method of mixing 
the composite flocculate and making the mixture into sheet, particularly 
the gas permeability and voids of the sheet are uniform and the material 
can be satisfactorily utilized as a filter. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will be explained in more detail by the following 
nonlimiting examples. 
EXAMPLE 1 
Twenty parts by weight of titanium oxide (P25S6 manufactured by Japan 
Aerosil Co., Ltd., specific surface area: 62 m.sup.2 /g) as a 
photoreactive semiconductor and 80 parts by weight of active carbon 
(KURARAY COAL GW manufactured by Kuraray Chemical Co., Ltd., standard 
particle size: 20-42 mesh) as a carrier in the form of powder were mixed 
by Henschel mixer to obtain a mixed powder (a). Separately, 94 parts by 
weight of water was added to 6 parts by weight of microfibrillated 
microfiber (CELLISH KY-100S manufactured by Daicel Ltd., fiber diameter: 
0.2-0.6 .mu.m and solid content: 25% by weight) and the fiber was 
dispersed for 2 hours by a homomixer (manufactured by Tokushu Kikakogyo 
Co., Ltd.) to obtain an aqueous dispersion (a). Under mechanical mixing, 
33 parts by weight of the aqueous dispersion (a) was slowly added dropwise 
to the mixed powder (a) in the manner of spraying to obtain a 
photoreactive noxious substance purging agent (A) in wet state. This was 
dried at 150.degree. C. for 30 minutes to obtain a powdery photoreactive 
noxious substance purging agent (A). 
Four parts by weight of the photoreactive noxious substance purging agent 
(A) in wet state was added to 100 parts by weight of pure water with 
stirring. After the mixture was left to stand for a certain time, 
turbidity of the supernatant liquid was measured by a Poick integrating 
sphere type turbidity meter (SET-PT-501D manufactured by Mitsubishi 
Chemical Industries, Ltd., cell length: 50 mm) to obtain 570 ppm. 
Two grams of the powdery photoreactive noxious substance purging agent (A) 
was charged in a closable container of 5.6 liters. Two containers 
containing the photoreactive noxious substance purging agent (A) were 
prepared, and one of them was provided with a 6 W black lamp so that the 
container can be irradiated thereby at a distance of about 5 cm. Into the 
containers was introduced 4 ml (about 500 ppm) of acetaldehyde saturated 
gas, and concentration of acetaldehyde in the containers was measured at 
intervals of a given time by a gas chromatography with FID detector. After 
lapse of 1 hour, 2 hours and 3 hours, saturated gas of acetaldehyde was 
similarly introduced, and concentrations of acetaldehyde in the containers 
with time were measured. The results are shown in FIG. 1. 
The abscissa axis shows time and the ordinate axis shows relative value of 
concentration of acetaldehyde. Of the two results in FIG. 1, the solid 
line indicates the results when irradiation with the black lamp was 
carried out and the broken line indicates the results when the irradiation 
was not carried out. Since acetaldehyde was adsorbed to the active carbon 
as a carrier, the concentration of acetaldehyde decreased irrespective of 
whether the irradiation with light was carried out or not, but when the 
irradiation was not carried out, the concentration of acetaldehyde 
gradually increased with lapse of time while when the irradiation was 
carried out, increase in the concentration of acetaldehyde with lapse of 
time was not seen. As a result, it was confirmed that the photoreactive 
noxious substance purging agent (A) had noxious substance removing ability 
with light in addition to a strong adsorptivity of the adsorbing material. 
EXAMPLE 2 
A nonwoven fabric made of polypropylene fibers (basis weight: 40 g/m.sup.2, 
gas permeability: 55 cm.sup.3 /cm.sup.2 .multidot.S) was processed to make 
uneven. The powdery photoreactive noxious substance purging agent (A) 
obtained in Example 1 was put on the nonwoven fabric to fill the dented 
portions with the agent in an amount of 200 g/m.sup.2. This was covered 
with another nonwoven fabric of 30 g/m.sup.2 (gas permeability 80 cm.sup.3 
/cm.sup.2 .multidot.S) and this upper nonwoven fabric was heat melt bonded 
to the lower nonwoven fabric at the protruded portions of the lower 
nonwoven fabric to make a photoreactive noxious substance purging material 
(B). The resulting photoreactive noxious substance purging material (B) 
was cut along the heat melt bonded portions and rubbed in the palms of the 
hands to find that no powder fell off from the sheet. Furthermore, this 
was introduced into water and stirred, but substantially no haze was 
produced, and liberation of the photoreactive semiconductor was not seen. 
This photoreactive noxious substance purging material (B) was cut to 25 
cm.times.13 cm and put on the bottom of a square-shaped closed container 
of 40 cm.times.30 cm.times.30 cm having a 6 W black lamp. In this 
container was charged acetaldehyde at a concentration of 300 ppm, and the 
photoreactive noxious substance purging material (B) was irradiated with 
light at a distance of about 20 cm above the material. Concentration of 
acetaldehyde after lapse of 20 minutes was determined by the apparatus 
used in Example 1 to find that the concentration of acetaldehyde decreased 
to 15 ppm. 
EXAMPLE 3 
Five parts by weight of a polyethylene fine powder was mixed with 100 parts 
by weight of the powdery photoreactive noxious substance purging agent (A) 
obtained in Example 1, and the mixture was allowed to be uniformly present 
between two nonwoven fabrics comprising polypropylene fibers (basis 
weight: 20 g/m.sup.2, gas permeability: 95 cm.sup.3 /cm.sup.2 
.multidot.S). The two sheets were allowed to adhere with heat by a pair of 
hot rolls having a mesh pattern to make a photoreactive noxious removing 
material (C). Amount of the enclosed photoreactive noxious substance 
purging agent (A) was 100 g/m.sup.2. The resulting photoreactive noxious 
substance purging material (C) was cut along the heat bonded portions and 
rubbed in the palms of hands to find that no powder fell off from the 
sheets. Furthermore, this was introduced into water and stirred to cause 
substantially no haze, and liberation of the photoreactive semiconductor 
was not seen. 
In the same manner as in Example 2, the acetaldehyde removing ability of 
the photoreactive noxious substance purging material (C) was measured to 
find that the concentration decreased from initial 300 ppm to 20 ppm after 
lapse of 30 minutes and, thus, the removing material (C) had good 
acetaldehyde removing ability. 
COMATIVE EXAMPLE 1 
Four parts by weight of the mixed powder (a) of titanium oxide and active 
carbon prepared in Example 1 was added to 100 parts by Weight of pure 
water with stirring. After the mixture was left to stand for the same time 
as in Example 1, tubidity of the supernatant liquid was measured by the 
turbidity meter used in Example 1 to obtain 6000 ppm. Thus, it was found 
that at least titanium oxide was clearly liberated in water as compared 
with Example 1 where titanium oxide which was a photoreactive 
semiconductor was included in the microfibrillated microfibers. 
COMATIVE EXAMPLE 2 
Five parts by weight of polyethylene fine powder was mixed with 100 parts 
by weight of the mixed powder (a) of titanium oxide and active carbon 
prepared in Example 1. The mixture was allowed to be uniformly present 
between two nonwoven fabrics comprising polypropylene fibers used in 
Example 3, and the two nonwoven fabrics were allowed to adhere with heat 
by hot rolls having a mesh pattern in the same manner as in Example 3 to 
obtain a photoreactive noxious substance purging material (D). Amount of 
the enclosed mixed powder (a) was 100 g/m.sup.2. 
This photoreactive noxious substance purging material (D) was cut to a size 
of 20 cm.times.12 cm along the heat adhering portions, and when this was 
rubbed in the palms of hands, white powder adhered to the palms. When this 
was introduced in water and stirred, titanium oxide was liberated from the 
sheets into water, resulting in considerable hazing of water and 
handleability was inferior. 
EXAMPLE 4 
Forty parts by weight of polyethylene terephthalate fiber having a fineness 
of 0.15 denier (d) (fiber diameter: about 4 .mu.m) and a fiber length of 
7.5 mm and 60 parts by weight of polyester flame retardant fiber (TREVIRA 
CS manufactured by Teijin, Limited) having a fineness of 1.5 d (fiber 
diameter: about 12.4 .mu.m) and a fiber length of 15 mm were introduced 
into water together with a nonionic surface active agent, followed by 
vigorously stirring by a pulper until no bundles of fibers were present. 
After diluted with water, to the product was added a polyacrylamide 
solution (viscosity modifier) with gentle stirring by an agitator to 
increase the viscosity, followed by continuing the stirring to obtain a 
slurry of uniformly dispersed fibers. A nonwoven fabric was obtained from 
the slurry by a cylinder paper machine. 
This nonwoven fabric was placed on a metal net made of stainless steel 
corresponding to 100 mesh and a water flow was jetted onto the web from 
above to entangle the fibers. For entanglement of the fibers, five nozzle 
heads fitted with nozzles were used to carry out the entanglement of the 
fibers once on each of the front and back sides. Table 1 shows diameter of 
nozzle (water flow) and intervals of nozzles (water flow) of each head, 
and pressure. On both sides, the head No. 5 was used for adjustment of the 
surface with a narrow water flow of low pressure. After completion of the 
entanglement, the nonwoven fabric was dried by an air-through drier. The 
basis weight of the resulting flame retardant polyester nonwoven fabric 
was 60 g/m.sup.2 and the gas permeability was 60 cm.sup.3 /cm.sup.2 
.multidot.S. 
TABLE 1 
______________________________________ 
Head No. 
1 2 3 4 5 
______________________________________ 
Diameter of nozzle (.mu.m) 
120 100 100 100 80 
Space between nozzle (mm) 
1.2 0.6 0.6 0.6 0.8 
The number of row 
2 1 1 1 2 
Pressure (kg/cm.sup.2) 
100 100 100 100 30 
______________________________________ 
Twenty parts by weight of titanium oxide (ST-31 manufactured by Ishihara 
Sangyo Kaisha Ltd., specific surface area: 220 m.sup.2 /g) and 80 parts by 
weight of the active carbon used in Example 1 as a carrier in the form of 
powder were mixed by a cylindrical mixer for 2 hours to obtain a mixed 
powder (b). Separately, 98 parts by weight of water was added to 2 parts 
by weight of microfibrillated micro-Kevlar fiber (CELLISH KY-400S 
manufactured by Daicel Ltd., fiber diameter: 0.2-0.6 .mu.m) and the fiber 
was dispersed for 2 hours by a homomixer (manufactured by Tokushu 
Kikakogyo Co., Ltd.) to obtain an aqueous dispersion (b). Under mechanical 
mixing, 30 parts by weight of the aqueous dispersion (b) was slowly added 
dropwise to the mixed powder (b) in the manner of spraying to granulate 
the fiber, followed by drying at 150.degree. C. for 30 minutes to obtain a 
powdery photoreactive noxious substance purging agent (B). This was placed 
on the above flame retardant polyester nonwoven fabric in an amount of 10 
g/m.sup.2, and thereon was put another flame retardant polyester nonwoven 
fabric, followed by pressing by two embossing rolls heated to 150.degree. 
C. to obtain a photoreactive noxious substance purging material (E). 
EXAMPLE 5 
Twenty parts by weight of titanium oxide used in Example 4 and 80 parts by 
weight of a composite phillosilicate of 20-40 mesh (MIZUKANITE 
manufactured by Mizusawa Kagaku Kogyo Co., Ltd.) as a carrier in the form 
of powder were mixed by a cylindrical mixer for 2 hours to obtain a mixed 
powder (c). In the same manner as in Example 4, a powdery photoreactive 
noxious substance purging agent (C) was prepared from this mixed powder 
(c) and the aqueous dispersion (b) prepared in Example 5. This was placed 
on the flame retardant polyester nonwoven fabric made in Example 4 in an 
amount of 10 g/m.sup.2, and thereon was put another flame retardant 
polyester nonwoven fabric, and a photoreactive noxious substance purging 
material (F) was obtained in the same manner as in Example 4. 
EXAMPLE 6 
Fifteen parts by weight of a vinyl acetate resin powder which was a 
thermoplastic resin and 100 parts by weight of the photoreactive noxious 
substance purging agent (B) prepared in Example 4 were mixed by a 
cylindrical mixer for 2 hours to obtain a mixed powder (d). This was 
placed on the flame retardant polyester nonwoven fabric made in Example 4 
in an amount of 50 g/m.sup.2, and thereon was put another flame retardant 
polyester nonwoven fabric, and a photoreactive noxious substance purging 
material (G) was obtained in the same manner as in Example 4. 
EXAMPLE 7 
Fifteen parts by weight of the thermoplastic resin used in Example 6 and 
100 parts by weight of the photoreactive noxious substance purging agent 
(C) prepared in Example 5 were mixed by a cylindrical mixer for 2 hours to 
obtain a mixed powder (e). This mixed powder (e) was placed on the flame 
retardant polyester nonwoven fabric made in Example 4 in an amount of 50 
g/m.sup.2, and thereon was put another flame retardant polyester nonwoven 
fabric, and a photoreactive noxious substance purging material (H) was 
obtained in the same manner as in Example 4. 
COMATIVE EXAMPLE 3 
A polyester nonwoven fabric having a basis weight of 60 g/m.sup.2 was made 
in the same manner as in Example 4, except that polyester fiber having a 
fineness of 1.5 d and a fiber length of 15 mm (manufactured by Teijin, 
Limited) was used in place of the polyester flame retardant fiber used for 
making the flame retardant polyester nonwoven fabric in Example 4. The 
resulting nonwoven fabric had a gas permeability of 60 cm.sup.3 /cm.sup.2 
.multidot.S. 
On this polyester nonwoven fabric was placed the active carbon used in 
Example 1 in an amount of 10 g/m.sup.2, and thereon was put another flame 
retardant polyester nonwoven fabric, and an active carbon noxious 
substance removing material was obtained in the same manner as in Example 
4. 
COMATIVE EXAMPLE 4 
On the polyester nonwoven fabric made in Comparative Example 3 was placed 
the mixed powder (c) prepared in Example 5 in an amount of 50 g/m.sup.2, 
and thereon was put another polyester nonwoven fabric, and a photoreactive 
noxious substance purging material (I) was obtained in the same manner as 
in Example 4. 
Deodorization properties, antimicrobial properties, flammability and 
peeling strength of the photoreactive noxious substance purging materials 
(E)-(I) and the active carbon noxious substance removing material produced 
in Examples 4-7 and Comparative Examples 3 and 4 were evaluated by the 
following test methods. The results are shown in Table 2. 
&lt;Test methods &gt; 
(1) Deodorization properties: 
(A) Deodorization by irradiation with ultra-violet rays: 
The photoreactive noxious substance purging material was cut to 10 
cm.times.20 cm and put on the bottom of the closable container provided 
with a 6 W black lamp which was used in Example 1. In the same manner as 
in Example 1, 4 ml of acetaldehyde saturated gas was charged in this 
container, and the photoreactive noxious substance purging material was 
irradiated with ultraviolet rays by the black lamp. Concentration of 
acetaldehyde after irradiation for 30 minutes was measured by the gas 
chromatography used in Example 1. Further, the procedure of charging 4 ml 
of acetaldehyde saturated gas in the container, irradiating ultraviolet 
rays and measuring the concentration of acetaldehyde was repeated three 
times. 
(B) Deodorization without irradiation of ultraviolet rays: 
The concentration of acetaldehyde was measured in the same manner as in the 
above method (A), except that the sample was left to stand in the dark 
without irradiating ultraviolet rays. 
(2) Antimicrobial properties: 
The photoreactive noxious substance purging material was cut to 10 
cm.times.10 cm and was dipped in an aqueous solution of Pseudomonas 
aeruginosa of 70,000/ml in concentration. The sheet was irradiated with 
ultraviolet rays by a 6 W black lamp at a distance of about 20 cm from 
above for 4 hours. After irradiation of 4 hours, the number of surviving 
cells in the solution was measured by pour plate culturing method using a 
standard agar medium (culturing at 35.degree. C. for 48 hours) and shown 
in terms of concentration of Pseudomonas aeruginosa. Ratio of the 
concentration of Pseudomonas aeruginosa after irradiation of ultraviolet 
rays for 4 hours to the initial concentration is shown as reduction rate 
of concentration of Pseudomonas aeruginosa due to the irradiation with 
ultraviolet rays. 
(3) Flammability: 
This was tested in accordance with the method A-1 of JIS L1091. 
(4) Peeling strength: 
The photoreactive noxious substance purging material was cut to 2 
cm.times.15 cm, and one end thereof was notched to form two sheets. The 
end parts of these sheets were peeled from each other by 7 cm and the end 
of each of the peeled sheets was fixed by a chuck and the peeling strength 
was measured by a tensilon universal testing machine (manufactured by 
Orienteck Co., Ltd.) at a distance (span) between the chucks of 10 cm. An 
average of 10 maximum peeling strengths is shown as interlayer peeling 
strength. 
TABLE 2 
__________________________________________________________________________ 
Examples Comparative Examples 
4 5 6 7 3 4 
__________________________________________________________________________ 
Concentration of acetaldehyde (ppm) 
Irradiated with ultraviolet ray 
The 1st charging 
80 100 
15 20 85 20 
The 2nd charging 
80 105 
18 20 100 25 
The 3rd charging 
85 110 
15 25 105 25 
The 4th charging 
80 105 
15 20 110 20 
Not irradiated with ultraviolet ray 
The 1st charging 
85 105 
18 120 85 110 
The 2nd charging 
95 170 
25 140 100 135 
The 3rd charging 
100 
190 
30 160 105 150 
The 4th charging 
110 
230 
40 170 110 165 
Reduction rate of concentration of 
1/80 
1/50 
1/200 
1/100 
1/1 1/100 
pseudomonas aeruginosa by 
irradiation with ultraviolet ray 
Flammability Ignited 
Ignited 
Heating for 1 minute and burnt 
and burnt 
Char area (cm.sup.2) 
25 25 28 28 
Afterflame (sec) 
2 2 3 3 
Afterglow (sec) 
5 5 5 5 
Length of char (cm) 
18 18 20 20 
After 30 seconds from ignition 
Char area (cm.sup.2) 
28 28 30 30 
Afterflame (sec) 
2 2 3 3 
Afterglow (sec) 
5 5 5 5 
Length of char (cm) 
19 19 20 20 
Criterion of flammability 
3 3 3 3 
Interlayer peeling strength.sup.1) (g) 
280 
290 
525 520 280 280 
__________________________________________________________________________ 
Note 
.sup.1) The interlayer peeling strengths in Examples 1-4 and Comparative 
Example 1 are in practically acceptable range. The interlayer peeling 
strength in Comparative Example 2 was practically unacceptable. 
It can be seen from Table 2 that the photoreactive noxious substance 
purging material (E) enclosing at least the photoreactive semiconductor 
(the present invention) decomposed the greater amount of acetaldehyde by 
irradiation with light. On the other hand, in the case of the active 
carbon noxious substance removing material containing no photoreactive 
semiconductor (not the present invention), amount of acetaldehyde 
decreased than the total charging amount of acetaldehyde due to the 
noxious substance adsoptivity of the active carbon, but there was no 
difference in the removing effect with and without the irradiation. 
Furthermore, the active carbon noxious substance removing material was 
inferior to the photoreactive noxious substance purging material (E) of 
the same total amount of the enclosure in both the acetaldehyde removing 
ability and the reduction rate of concentration of Pseudomonas aeruginosa 
by irradiation with light. Furthermore, the active carbon noxious 
substance removing material ignited in the flammability test because the 
nonwoven fabrics enclosing the enclosure had no frame retardancy. 
The photoreactive noxious substance purging material (I) containing the 
photoreactive semiconductor as one of the components of the enclosure (not 
the sample of the present invention) was not inferior to other 
photoreactive noxious substance purging materials (E)-(H) in both the 
acetaldehyde removing ability and the reduction rate of concentration of 
Pseudomonas aeruginosa by irradiation with light, but it ignited in the 
flammability test because the nonwoven fabrics enclosing the enclosure had 
no frame retardancy like the active carbon noxious substance removing 
material. Furthermore, it was low in interlayer peeling strength probably 
because the thermoplastic resin was not used in the enclosure although the 
amount of the enclosure was large, and when it was rubbed in the palms of 
hands, the enclosure fell off. 
As compared with these active carbon noxious substance removing material 
and the photoreactive noxious substance purging material (I), the 
photoreactive noxious substance purging material (E)-(H) of the present 
invention were not only superior in the deodorization and antimicrobial 
properties with irradiation of light, but also were practically acceptable 
in both the flammability and the peeling strength. 
EXAMPLE 8 
Ten parts by weight of the photoreactive semiconductor used in Example 1, 
10 parts by weight of active carbon (manufactured by Wako Junyaku Kogyo 
Co., Ltd., average particle diameter: 5 .mu.m) as a carrier and 2 parts by 
weight (solid content) of the microfibrillated microfiber used in Example 
1 were introduced into water and mechanically mixed by a mixer, followed 
by adding 0.02 part by weight of aluminum sulfate as a flocculant to form 
an aqueous liquid (a) of a composite flocculate containing the 
photoreactive semiconductor. 
Separately, a small amount of a dispersant (PRIMAL 850 manufactured by 
Japan Acryl Chemical Co., Ltd.) was added to 38 parts by weight of a 
thermoplastic resin fiber having a fineness of 0.5 d and a fiber length of 
5 mm (polyester fiber manufactured by Teijin, Limited) and 40 parts by 
weight of a thermoplastic resin fiber having a sheath-core structure and a 
fineness of 2 d and a fiber length of 5 mm (MELTY #4080 manufactured by 
Unitika, Ltd.) to prepare a thermoplastic resin fiber dispersion (a). The 
aqueous liquid (a) of composite flocculate and the thermoplastic resin 
fiber dispersion (a) were mixed with stirring and an anion-modified 
polyacrylamide was further added to stabilize the liquid system, and, 
thereafter, a photoreactive noxious substance purging material (J) having 
a basis weight of 100 g/m.sup.2 was prepared from the mixture by a 
cylinder paper machine and dried at 100.degree. C. 
The photoreactive noxious substance purging material (J) was cut to 12 
cm.times.20 cm and put in the two containers used in Example 1, one of 
which was constructed so that it could be irradiated with a 6 W black lamp 
at a distance of about 5 cm. Saturated gas of acetaldehyde was charged in 
the containers, and concentration of acetaldehyde in the containers was 
measured at intervals of a given time by the gas chromatography used in 
Example 1. Similarly, saturated gas of acetaldehyde was charged again 
after lapse of 1 hour and 2 hours, and concentrations of acetaldehyde in 
the containers with lapse of time were measured. The results are shown in 
FIG. 2. 
Since acetaldehyde was adsorbed to active carbon, concentration of 
acetaldehyde decreased irrespective of irradiation with light or not, but 
as is clear from FIG. 2, when light was not irradiated, the concentration 
gradually increased by the repeated charging of acetaldehyde while in the 
case of the container irradiated with light, the concentration of 
acetaldehyde did not increase due to the effect of the photoreactive 
semiconductor even by charging again acetaldehyde. Thus, it was confirmed 
that the photoreactive noxious substance purging material (J) had the 
noxious substance removing ability with light in addition to the 
adsorptivity of the active carbon. 
Furthermore, when the photoreactive noxious substance purging material (J) 
was irradiated with light by a 10 W black lamp for 10 days, no falling off 
of powder was seen in the container. Moreover, when the surface of the 
removing material (J) was rubbed by fingers, no white powder adhered to 
the fingers and good state could be maintained. 
EXAMPLE 9 
Ten parts by weight of the photoreactive semiconductor used in Example 1, 
10 parts by weight of a composite phillosilicate pigment (MIZUKANITE AP 
manufactured by Mizusawa Kagaku Kogyo Co., Ltd., average particle 
diameter: 2 .mu.m) as a carrier and 2 parts by weight of a 
microfibrillated microfiber (CELLISH KY-400 manufactured by Daicel, 
Limited) were introduced into water and mechanically dispersed, followed 
by adding polyaluminum chloride ( manufactured by Mizusawa Kagaku Kogyo 
Co., Ltd.) as a flocculant to obtain an aqueous liquid (b) of composite 
flocculate. This was mixed with the thermoplastic resin fiber dispersion 
(a) prepared in Example 8 with stirring, and an anion-modified 
polyacrylamide was further added to stabilize the liquid system, and, 
thereafter, a photoreactive noxious substance purging material (K) having 
a basis weight of 100 g/m.sup.2 was prepared from the mixture by a 
cylinder paper machine and dried at 100.degree. C. 
Using the photoreactive noxious substance purging material (K), change in 
the concentration of acetaldehyde was measured. When the material was not 
irradiated with light, acetaldehyde did not substantially decrease 
probably because the carrier did not adsorb acetaldehyde while when it was 
irradiated with light, the concentration decreased to 1/10 in about 40 
minutes. It was confirmed from these results that the photoreactive 
noxious substance purging material (K) also had the noxious substance 
removing ability with light. Furthermore, when the photoreactive noxious 
substance purging material (K) was irradiated with light by a 10 W black 
lamp for 10 days, no falling off of powder was seen in the container, and, 
furthermore, when the surface of the removing material (K) was rubbed by 
fingers, no white powder adhered to the fingers and good state could be 
maintained. 
COMATIVE EXAMPLE 5 
An aqueous liquid (c) of composite flocculate was prepared in the same 
manner as in Example 8, except that titanium oxide as the photoreactive 
semiconductor was not used and the microfibrillated microfiber and active 
carbon were mixed at a ratio of 1:5. Using the resulting aqueous liquid 
(c) of composite flocculate and the thermoplastic resin fiber dispersion 
(a) prepared in Example 8, a noxious substance removing material (L) of 
the same mixing ratio and the same basis weight as of the removing 
material (J) was made in the same manner as in Example 8. The acetaldehyde 
removing ability of this noxious substance removing material (L) was 
measured in the same manner as in Example 8. Since acetaldehyde was 
adsorbed to the active carbon, the concentration of acetaldehyde 
decreased, but as in Comparative Example 3, with repeatedly charging 
acetaldehyde, the concentration of acetaldehyde in the container increased 
and there was substantially no difference in increment depending on 
whether irradiation of light was carried out or not. It was confirmed that 
the noxious substance removing material (L) did not have at least the 
noxious substance removing ability with light. 
COMATIVE EXAMPLE 6 
Without using carrier, the microfibrillated microfiber used in Example 1 
and titanium oxide used in Example 4 as the photoreactive semiconductor at 
a ratio of 1:5 were introduced into water and mechanically mixed by a 
mixer, and thereto was further added 0.1 part by weight of sodium 
aluminate to obtain an aqueous liquid (d) of composite flocculate. 
The aqueous liquid (d) of composite flocculate and the thermoplastic resin 
fiber dispersion (a) prepared in Example 8 were mixed with stirring at the 
same mixing ratio as in Example 1, and a photoreactive noxious substance 
purging material (M) of the same basis weight as in Example 8 was prepared 
in the same manner as in Example 8. The acetaldehyde removing ability of 
the photoreactive noxious substance purging material (M) was measured by 
the same method as in Example 8 to find that the concentration of 
acetaldehyde decreased in the container irradiated with light, and the 
removing material (M) had noxious substance removing ability with light. 
However, when the photoreactive noxious substance purging material (M) was 
irradiated with light by a 10 W black lamp for 10 days, though no falling 
off of powder was seen in the container, but when the surface of the 
removing material (M) was rubbed by fingers, white powder adhered to the 
fingers, and it was confirmed that the removing material (M) deteriorated 
with light. 
EXAMPLE 10 
An aqueous liquid (e) of composite flocculate was prepared using the same 
materials and the same method as in Example 8, except that the titanium 
oxide was replaced with the same amount of ultrafine zinc oxide particles 
(F60 manufactured by Mitsubishi Material Co., Ltd., specific surface area: 
60 m.sup.2 /g) as photoreactive semiconductor. The resulting aqueous 
liquid (e) of composite flocculate was mixed with the thermoplastic resin 
fiber dispersion (a) prepared in Example 8 at the same solid content ratio 
as in Example 8 with stirring, and an anion-modified polyacrylamide was 
further added to stabilize the liquid system, and, thereafter, a 
photoreactive noxious substance purging material (N) having a basis weight 
of 100 g/m.sup.2 was prepared in the same manner as in Example 8 and dried 
at 100.degree. C. 
Change in the concentration of acetaldehyde was measured with the 
photoreactive noxious substance purging material (N) in the same manner as 
in Example 8. It was confirmed that the removing material (N) was inferior 
in the noxious substance removing ability with light to the removing 
material (J), but had a sufficient noxious substance removing ability with 
light. Furthermore, when the photoreactive noxious substance purging 
material (N) was irradiated with light by a 10 W black lamp for 10 days, 
no falling off of powder was seen in the container, and, besides, when the 
surface of the removing material (N) was rubbed by fingers, no powder 
adhered to the fingers, and good state could be maintained as in Example 
8. 
EXAMPLE 11 
Ten parts by weight (interms of solid matter) of metatitanic acid 
(manufactured by Tochem Products Co., Ltd.) as a photoreactive 
semiconductor was dispersed in water, and the dispersion was neutralized 
with an aqueous sodium hydroxide solution. To this dispersion were added 
10 parts by weight of magnesium carbonate and 2 parts by weight of the 
microfibrillated microfiber used in Example 1, and an aqueous liquid (f) 
of composite flocculate was prepared in the same manner as in Example 8. 
Separately, 23 parts by weight of a thermoplastic resin fiber having a 
fineness of 0.5 d and a fiber length of 5 mm (polyester fiber manufactured 
by Teijin, Limited), 30 parts by weight of a thermoplastic resin fiber 
having a fineness of 2 d and a fiber length of 5 mm (polyester fiber 
manufactured by Teijin, Limited) and 25 parts by weight of a thermoplastic 
resin fiber having a sheath-core structure and a fineness of 2 d and a 
fiber length of 5 mm (MELTY #4080 manufactured by Unitika, Ltd.) were 
introduced into water, and thereto was added a small amount of a 
dispersant to prepare a thermoplastic resin fiber dispersion (b). Using 
the aqueous liquid (f) of composite flocculate and the thermoplastic resin 
fiber dispersion (b), a photoreactive noxious substance purging material 
(0) was prepared at the same ratio and basis weight as in Example 8 and in 
the same manner as in Example 8 and dried at 130.degree. C. 
Change in the concentration of acetaldehyde was measured with the 
photoreactive noxious substance purging material (0) in the same manner as 
in Example 8. It was confirmed that the removing material (0) also had the 
noxious substance removing ability with light because concentration of 
acetaldehyde greatly decreased only when light was irradiated. 
Furthermore, when the removing material (0) was irradiated with light by a 
10 W black lamp for 10 days, no falling off of powder was seen in the 
container, and, besides, when the surface of the removing material (N) was 
rubbed by fingers, no white powder adhered to the fingers, and good state 
could be maintained. 
EXAMPLE 12 
An anion-modified polyacrylamide was added to the thermoplastic resin fiber 
dispersion (b) prepared in Example 11 and comprising the three 
thermoplastic resin fibers and the dispersant, and after stabilization of 
the liquid system, a thermoplastic resin fiber sheet having a basis weight 
of 78 g/m.sup.2 was made by a cylinder paper machine. 
Separately, an aqueous liquid (g) of composite flocculate was prepared in 
the same manner as in Example 8 using 10 parts by weight of titanium oxide 
used in Example 1, 10 parts by weight of magnesium carbonate used in 
Example 11 as a carrier and 2 parts by weight of the microfibrillated 
microfiber used in Example 1. This aqueous liquid (g) was coated on one 
side of the above thermoplastic resin fiber sheet at a solid coating 
amount of 11 g/m.sup.2 and dried to obtain a photoreactive noxious 
substance purging material (P). 
Change in the concentration of acetaldehyde was measured with the 
photoreactive noxious substance purging material (P) by irradiating the 
coated side of the removing material (P) in the same manner as in Example 
8. It was confirmed that the removing material (P) also had the noxious 
substance removing ability with light because concentration of 
acetaldehyde greatly decreased only when light was irradiated. 
Furthermore, when the removing material (P) was irradiated with light by a 
10 W black lamp for 10 days, no falling off of powder was seen in the 
container, and, besides, when the surface of the removing material (P) was 
rubbed by fingers, no white powder adhered to the fingers, and good state 
could be maintained. 
EXAMPLE 13 
An aqueous dispersion of a photoreactive semiconductor, a composite 
phillosilicate, Kosei clay and a microfibrillated microfiber, and an 
aqueous dispersion of a ceramic fiber and a glass fiber were prepared 
using 8 parts by weight of the photoreactive semiconductor used in Example 
4, 8 parts by weight of the carrier used in Example 5, 5 parts by weight 
of the microfibrillated microfiber used in Example 1, 42 parts by weight 
of a ceramic fiber (SC FIBER 1400 manufactured by Shin-nittetsu Chemical 
Co., Ltd.), 8 parts by weight of a glass fiber and 29 parts by weight of 
Kosei clay as an inorganic adhesive. Then, the resulting two aqueous 
dispersions were mixed, and a wet paper was made therefrom by wet paper 
making process using a cylinder paper machine. Twenty wet papers thus 
obtained were laminated, and the laminate was put between nets of 100 mesh 
and heated and pressed at 140.degree. C. and 40 kgf/cm.sup.2 for 60 
minutes to integrate them to obtain a board-like photoreactive noxious 
substance purging material (Q) of 1.5 mm thick. 
EXAMPLE 14 
Ten parts by weight of the photoreactive semiconductor used in Example 1, 
10 parts by weight of the carrier used in Example 5, 20 parts by weight of 
a microfibrillated aramid microfiber (NORMEX ARAMID FIBRID manufactured by 
DuPont Japan Co., Ltd.), 3 parts by weight of a microfibrillated 
cellulosic microfiber (CELLISH KY-100S manufactured by Daicel, Ltd.) and 
47 parts by weight of an aramid fiber (CORNEX 6 manufactured by Teijin 
Limited) were stirred in water to disperse them, and a wet paper was made 
from the dispersion by wet paper making process using a cylinder paper 
machine in the same manner as in Example 13. Twenty-two wet papers thus 
obtained were laminated, and the laminate was put between nets of 100 mesh 
and heated and pressed at 140.degree. C. and 40 kgf/cm.sup.2 for 60 
minutes to integrate them to obtain a board-like photoreactive noxious 
substance purging material (R) of 0.5 mm thick. 
COMATIVE EXAMPLE 7 
An aqueous dispersion of a composite phillosilicate, Kosei clay and a 
microfibrillated microfiber, and an aqueous dispersion of a ceramic fiber 
and a glass fiber were prepared in the same manner as in Example 13, 
except that the photoreactive semiconductor was not used. A wet paper was 
made therefrom by wet paper making process using a cylinder paper machine. 
Twenty wet papers thus obtained were laminated, and a board (S) of 1.5 mm 
thick was made in the same manner as in Example 13. 
COMATIVE EXAMPLE 8 
A board (T) of 0.5 mm thick was made in the same manner as in Example 14, 
except that the photoreactive semiconductor was not used and the active 
carbon used in Example 1 was used in place of the composite 
phillosilicate. 
The board-like photoreactive noxious substance purging materials (Q) and 
(R) produced in Examples 13 and 14 and the boards (S) and (T) produced in 
Comparative Examples 7 and 8 were evaluated on flammability (JIS L1091, 
Method A-2 &lt;45.degree. Meckel Burner method&gt;), tensile strength (JIS 
P8113), and flexural strength (JIS K7203), and deodorization properties 
and antimicrobial properties by the following test methods. The results 
are shown in Table 3. 
(1) Deodorization properties: 
The board was cut to 6 cm.times.20 cm and placed on the bottom of a 5.6 
liter closed container having a 6 W black lamp. In this container was 
charged 0.4 ml (about 50 ppm) of acetaldehyde saturated gas, and the board 
was irradiated with ultraviolet rays by the black lamp provided at a 
distance of about 20 cm above the board. Concentration of acetaldehyde 
after 60 minutes was measured in the same manner as in Example 1. 
(2) Antimicrobial properties: 
The board was cut to 5 cm.times.5 cm and 1 ml of Methicillin resistant 
Staphylococcus aureus 11D 1677 solution was dropped on the board to obtain 
a test piece. The same amount of the cell solution dropped on the test 
piece was stored in a laboratory dish and this was used as a control 
sample. The cell solution was prepared in the following manner. A culture 
solution of the test cells obtained by carrying out shaking culture on a 
broth medium (manufactured by Eiken Kagaku Co., Ltd.) at 35.degree. C. for 
18 hours was diluted to 20,000 times with a sterilized phosphoric acid 
buffer solution. 
The test piece and the control sample were placed at a distance of 15 cm 
under a light source of 15 W fluorescent lamp and stored at 25.degree. C. 
The number of surviving cells after stored for 6 hours and 24 hours was 
measured. 
The test piece and the control sample were washed with 10 ml of SCDLP 
medium (manufactured by Nippon Seiyaku Co., Ltd.) and the number of 
surviving cells in the washing liquid was measured by pour plate method 
(culturing at 35.degree. C. for 48 hours) using the standard agar medium 
(manufactured by Eiken Kagaku Co., Ltd.), and it was shown in terms of the 
number per the test piece and the control sample. 
TABLE 3 
__________________________________________________________________________ 
Examples Comparative Examples 
13 14 7 8 
__________________________________________________________________________ 
Concentration of acetaldehyde (ppm) 
5 5 25 10 
The number of surviving cells of 
methicillin resistant staphylococcus 
aureus.sup.1) 
At the beginning of test 
4 .times. 10.sup.5 
After 6 hours under fluorescent lamp 
2 .times. 10.sup.1 
After 24 hours under fluorescent lamp 
N.D..sup.2) 
Flammability 
Heating for 2 minutes 
Char area (cm.sup.2) 
0 10 0 10 
Afterfleame (sec) 0 2 0 2 
Afterglow (sec) 1 2 1 2 
Length of char (cm) 
0 8 0 8 
Ignitability Not ignited Not ignited 
After 6 seconds from ignition 
15 15 
Char area (cm.sup.2) 2 2 
Afterflame (sec) 2 2 
Afterglow (sec) 10 10 
Length of char (cm) 3 3 
Criterion of flammability 
3 3 3 3 
Tensile strength 
Lengthwise 19.9 20.1 
(Kg/15 mm) 
Crosswise 15.8 15.6 
Flexural strength 
Lengthwise 
78.3 76.2 
(Kg/cm.sup.2) 
Crosswise 
58.9 59.7 
__________________________________________________________________________ 
Notes 
.sup.1) The number of surviving cells for the control sample: 4 .times. 
10.sup.5 at the beginning of test, 4.4 .times. 10.sup.5 after 6 hours 
under fluorescent lamp, and 2.2 .times. 10.sup.3 after 24 hours under 
fluorescent lamp. 
.sup.2) This means that no cells were detected by this method of measurin 
the cell number. 
As can be seen from Table 3, the photoreactive noxious substance purging 
materials (Q) and (R) of the present invention can decompose the noxious 
substances such as malodorous substances and microorganisms with light and 
remove them, and, besides, they have practically usable various conditions 
as non-combustible, flame retardant and strong structural materials. 
Therefore, the board-like photoreactive noxious substance purging 
materials are suitable not only for wall materials, but also for various 
indoor and outdoor structural materials. 
As explained above, according to the present invention, a photoreactive 
noxious substance purging agent having excellent noxious substance 
removing ability with light and a photoreactive noxious substance purging 
material using the removing agent. The photoreactive noxious substance 
purging agent which comprises a photoreactive semiconductor, a carrier and 
a microfibrillated microfiber can be prevented from falling off of the 
photoreactive semiconductor even if it is particulate without greatly 
reducing the effective surface area of the semiconductor by the carrier 
and the microfiber, and the removing agent is excellent in continual 
noxious substance removing ability with light not only in rooms, but also 
in water. 
When this photoreactive noxious substance purging agent is enclosed in two 
or more sheets, at least one of which has gas permeability, not only the 
photoreactive noxious substance purging agent can be spread and held in a 
great area, but also it can be processed into optional shapes, and a 
photoreactive noxious substance purging material which has an excellent 
strength and from which the photoreactive noxious substance purging agent 
does not fall off even when used in water can be obtained. 
Furthermore, when a flame retardant nonwoven fabric is used as the gas 
permeable sheet in the photoreactive noxious substance purging material 
comprising at least a photoreactive semiconductor and a carrier enclosed 
between two or more gas permeable sheets, the removing material can be 
made wholly flame retardant since the photoreactive semiconductor and the 
carrier are inherently non-combustible and, besides, flexibility and hand 
of the removing material can be adjusted. 
Moreover, when a thermoplastic resin fiber is used together with the 
enclosures in the case of enclosing the enclosures between the sheets, the 
thermoplastic resin fiber acts as a binder to improve the adhesion between 
the sheets, and the enclosures can be enclosed in the greater amount and 
the strength can be further improved. 
As for the form of the photoreactive noxious substance purging material 
containing the photoreactive noxious substance purging agent which 
comprises a photoreactive semiconductor, a carrier and a microfibrillated 
microfiber, the removing material may be not only the type of the 
photoreactive noxious substance purging agent being enclosed between the 
sheets, but also a type of the photoreactive noxious substance purging 
agent being coated and a type of the photoreactive noxious substance 
purging agent being made into a sheet. These sheets can be utilized as 
filters not only in air, but also in water, and, furthermore, have 
excellent processability. 
These photoreactive noxious substance purging materials of various shapes 
and having various holding amounts of the photoreactive semiconductor can 
be selected, and can be cut to a suitable size and can easily remove 
noxious substances by decomposing them with mere irradiation of light. 
Therefore, they can be efficiently utilized for removing not only noxious 
substances contained in low concentrations in air such as malodor, but 
also noxious substances contained in low concentrations in water. 
The photoreactive noxious substance removing materilas of the present 
invention can be utilized as deodorizing sheets in automobiles, trains, 
etc. In this case, no special light irradiating devices are needed at the 
places exposed to sunlight. As method of using them at such places, they 
can be used as interior materials such as front board materials, wall 
materials and fitted to deodorizers, etc. in the folded form. Furthermore, 
they can be provided in the folded form at household articles such as shoe 
boxes, hangers, refrigerators, lockers, and cabinets. Moreover, they can 
be utilized as wall papers, floor materials and curtains in toilet, 
kitchen, bath room, and dressing room, and, in addition, containers for 
pet toilet. Furthermore, they can be used around fluorescent lamps because 
fluorescent lamps contain wavelengths of active light for photoreactive 
semiconductors. 
In hospitals, they can be used as materials of sheets and curtains, and as 
wall materials and floor materials of passages and treatment rooms. 
Further, they can be utilized as filters of household air conditioners, 
office air conditioners, cleaners, driers for wet refuses. These may be 
provided with exclusive light source devices, but since intermittent 
irradiation of light regenerates the deodorizing properties, they can be 
effectively used in the facilities which the sunlight strikes in the 
daytime. 
In water, they can be used as filters for improving quality of water in 
water supply and drainage, for purification of rivers and lakes, for final 
treatment of factory wastes, and for purification of water in bath and 
swimming pool. When they are used as floating materials on water, they are 
more effective since the sunlight can also be used as a light source.