Printing medium and ink jet print

Disclosed herein is a printing medium comprising a base material and an ink-receiving layer which comprises inorganic fine particles and a binder and is provided on the base material, wherein the inorganic fine particles are partly projected from a binder layer of the ink-receiving layer and contained in a proportion of 0.05 to 3 parts per 100 parts of the binder in terms of solids.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a printing medium suitable for use in 
ink-jet printing, a production process thereof, and an ink-jet printing 
method using this medium. 
2. Related Background Art 
An ink-jet printing method is a method in which printing is conducted by 
generating and flying droplets of an ink by one of various ink ejection 
systems, for example, an electrostatic attraction system, a system using a 
piezoelectric element to give an ink a mechanical vibration or change, or 
a system in which an ink is heated to form bubbles in the ink to use the 
pressure thus produced, and applying the droplets in whole or in part to a 
printing material such as paper or a plastic film coated with an 
ink-receiving layer. The ink-jet printing method attracts attention as a 
printing method which scarcely produces noise and can conduct high-speed 
printing and multi-color printing. 
As inks for ink-jet printing, inks comprising water as a principal 
component are mainly used from the viewpoints of safety, printability and 
the like. A polyhydric alcohol and/or the like are often added to such 
inks with a view toward preventing clogging of orifices and improving 
ejection stability. 
As printing materials suitable for use in ink-jet printing, there have 
hitherto been used glossy paper as described in Japanese Patent 
Publication No. 3-25352, which comprises a cast-coated paper web and a 
film formed thereon comprising polyvinyl alcohol having a saponification 
degree of from 50 to 90 mole % and a crosslinking agent, and a printing 
sheet for an over-head projector (OHP) as described in Japanese Patent 
Application Laid-Open No. 60-220750, which comprises a polyester film and 
a hydrophilic film provided thereon composed of water-soluble polyvinyl 
alcohol having a saponification degree of from 70 to 90 mole %. 
With the improvement in performance of ink-jet printing apparatus, such as 
speeding up of printing and multi-coloring of images, in recent years, 
ink-jet printing media have been also required to have higher and wider 
properties. 
More specifically, they are required to simultaneously satisfy, for 
example, the following properties: 
(1) having high ink absorptivity (absorbing capacity being great, and 
absorbing time being short); 
(2) providing dots high in optical density and clear in periphery; 
(3) providing dots having a substantially round shape and a smooth 
periphery; 
(4) undergoing scarce changes in the properties even at varied temperatures 
and humidities and no curling; 
(5) undergoing no blocking; 
(6) being able to stably store images formed thereon for a long period of 
time without deterioration (in particular, in a high-temperature and 
high-humidity environment); 
(7) being stable without undergoing deterioration even when stored for a 
long period of time (in particular, in a high-temperature and 
high-humidity environment); and 
(8) having good feeding property so as to smoothly move when charged into a 
printer and printed. 
More recently, printing media have been strongly requested to have good 
continuous feeding property in various printers. 
Besides, printing sheets for OHP, and the like are further required to have 
excellent transparency in addition to the above requirements. 
These properties are often in a relation of trade-off. It has hence been 
impossible to satisfy them at the same time by the conventionally known 
techniques. For example, the exemplified recording media of the prior art 
have comparable performance in dot shape and blocking resistance, but are 
poor in ink absorptivity. Therefore, they cause image smearing and 
unevenness of color strength due to ink running at areas high in image 
density, i.e., areas great in shot-in ink quantity. In addition, they 
cause color muddiness due to mixing of colors at boundaries between 
different colors, particularly, in the case of color printing. 
Further, it has recently been reported to use inks in which values of 
physical properties such as surface tension are different between a black 
ink and color inks to lessen bleeding between the black ink and the color 
inks. However, there are few examples of a printing material which 
exhibits good printability to all the inks different in physical property 
values. Further, any film for OHP satisfying the overall performance 
taking other properties such as fixing ability into consideration has not 
been yet obtained. 
With the progress of speeding up of recording, increasing of image density 
and coloring of images, and diversification of inks, as described above, 
defective ink fixing, deteriorated image quality and lowered shelf 
stability of the resulting print have become serious problems. 
Besides, in these existing constructions, no attention is paid to 
improvement in feeding property and continuous feeding property in various 
printers, which is particularly strongly required at present, as to the 
film for OHP, glossy paper or the like. Therefore, a major problem has 
been left in this respect. It has been scarcely proposed at present to 
improve the feeding property and continuous feeding property, and so such 
a problem must be solved. 
Further, as described in, for example, Japanese Patent Application 
Laid-Open Nos. 59-95188, 57-93193 and 62-170383, it has been reported to 
use an aqueous resin emulsion as a material of an ink-receiving layer. 
According to these compositions, an improving effect is recognized to some 
extent as to blocking. However, no improving effect is recognized at to 
the problem of the feeding property and continuous feeding property. 
In addition, these printing media cause image smearing and unevenness of 
color strength due to ink running at areas high in image density, i.e., 
areas great in shot-in ink quantity. 
SUMMARY OF THE INVENTION 
It is thus an object of the present invention to provide a 
light-transmitting or surface-gloss printing medium which satisfies both 
of image properties and properties of printing medium itself such as 
blocking resistance, and feeding property and continuous feeding property 
in various printers in a well-balanced relation, and an ink-jet printing 
method using this printing medium, and moreover to provide a 
light-transmitting or surface-gloss printing medium excellent in fixing 
ability, stackability after printing and the like, and an ink-jet printing 
method using this printing medium. 
Another object of the present invention is to provide a printing medium 
which scarcely undergoes deterioration even when the printing medium 
itself or an image formed thereon is left to stand for a long period of 
time in a high-temperature and high-humidity environment, and is excellent 
in fixing ability, stackability after printing and the like, and an 
ink-jet printing method using this printing medium. 
The above objects can be achieved by the present invention described below. 
According to the present invention, there is thus provided a printing 
medium comprising a base material and an ink-receiving layer which 
comprises inorganic fine particles and a binder and is provided on the 
base material, wherein the inorganic fine particles are partly projected 
from a binder layer of the ink-receiving layer and contained in a 
proportion of 0.05 to 3 parts per 100 parts of the binder in terms of 
solids. 
According to the present invention, there is also provided a printing 
medium comprising a base material and an ink-receiving layer provided on 
at least one side of the base material, wherein the ink-receiving layer 
has a structure that resin particles are held in a continuous film of a 
water-soluble resin, and inorganic fine particles are partly projected 
from the surface of the ink-receiving layer. 
According to the present invention, there is further provided an ink-jet 
printing method comprising ejecting an ink on any one of the printing 
media described above from an orifice of a recording head in accordance 
with a recording signal, thereby conducting printing. 
According to the present invention, there is still further provided a 
process for producing a printing medium comprising a base material and an 
ink-receiving layer provided on at least one side of the base material, 
which comprises applying a coating formulation comprising, as essential 
components, cationically modified polyvinyl alcohol, an aqueous resin 
emulsion and inorganic fine particles to the base material to form the 
ink-receiving layer in such a manner that the resulting ink-receiving 
layer has a structure that resin particles from the aqueous resin emulsion 
are held in the ink-receiving layer, and the inorganic fine particles are 
partly projected from the surface of the ink-receiving layer. 
According to the present invention, there is yet still further provided a 
printing medium comprising a base material and an ink-receiving layer 
provided on at least one side of the base material, wherein the 
ink-receiving layer comprises, as essential components, a water-soluble 
resin, a copolymer of vinylpyrrolidone and a hydrophobic monomer, and 
inorganic fine particles, and the inorganic fine particles are partly 
projected from the surface of the ink-receiving layer. 
According to the present invention, there is yet still further provided a 
method of forming images, which comprises forming an image on the printing 
medium described above by means of an ink-jet system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the course of developing printing paper suitable for use in ink-jet 
printing and a transparent film for over-head projectors, the present 
inventors have found printing media which are excellent in fixing ability 
and stackability after printing, far excellent in feeding property and 
continuous feeding property in various printers and satisfy these 
performance characteristics without deteriorating printing properties and 
image quality to any extent, thus leading to completion of the present 
invention. 
More specifically, as illustrated in FIG. 1A, the inorganic fine particles 
5 are partly projected from the surface of the binder layer of the 
ink-receiving layer 2, whereby the printing medium is improved in a 
tendency to be caught by pickup rollers in various printers, and so good 
feeding property to smoothly move can be realized. When the construction 
according to the present invention is used, blocking resistance also 
becomes good, and so entirely satisfactory performance can be achieved as 
to the continuous feeding property. 
Further it has been definitely shown that the use of the constitution that 
the inorganic fine particles are used, and they are projected from the 
binder layer can lessen bleeding to a significant extent compared with the 
use of organic fine particles, and also improve the ability to keep the 
quality of an image formed on the printing medium good. 
Examples of the inorganic fine particles useful in the practice of the 
present invention include fine particles of silica, alumina, aluminum 
silicate, magnesium silicate, basic magnesium carbonate, talc, clay, 
hydrotalcite, calcium carbonate, titanium oxide and zinc oxide. It goes 
without saying that they are not limited to these particles. Ink 
absorptiveness is not very required of these inorganic fine particles. 
For example, if particles of a high-water-absorptive resin are used as fine 
particles, the resin particles themselves also absorb ink to swell. As a 
result, the mechanical strength of the resin particles is lowered, and so 
the tendency to be caught by a pickup roller is deteriorated to a 
significant extent. Therefore, the feeding property and continuous feeding 
property of such a printing medium become different from a practicable 
level. 
In this case, if the inorganic fine particles are used, the mechanical 
strength can be kept good even after printing, and so the objects of the 
present invention can be satisfied. 
In order to make the effects of the invention clear, it is also necessary 
to partly project the inorganic particles from the surface of the binder 
layer of the ink-receiving layer as described above. 
With respect to a method of making such a structure, if the primary 
particle diameter of fine particles to be used, or the secondary particle 
diameter or average particle diameter thereof if the particles are liable 
to aggregate is greater than the thickness of the binder layer, it is 
ensured that the ink-receiving layer is constructed so as to project the 
inorganic particles from the surface of the binder layer of the 
ink-receiving layer. Even if the primary particle diameter of the fine 
particles to be used is smaller than the thickness of the binder layer, it 
is also consequentially possible to project the inorganic fine particles 
from the surface of the binder layer of the ink-receiving layer owing to 
fine particles existing in the surface of the binder layer. Since the fine 
particles are fully considered to exist in an aggregated state (in the 
form of secondary particles) (they generally exist in this form), the 
ink-receiving layer may be constructed so as to project the inorganic fine 
particles from the surface of the binder layer even if fine particles 
small in diameter are used. 
However, if the average particle diameter of these inorganic fine particles 
exceeds 5 times the thickness of the binder layer of the ink-receiving 
layer, a phenomenon of reduced surface strength, dusting or the like 
presents itself. It is hence not preferable to use fine particles having 
such a great diameter. On the other hand, it is consequentially possible 
for the ink-receiving layer to take a structure that the inorganic fine 
particles are projected from the surface of the binder layer even if the 
average particle diameter of these inorganic fine particles is smaller 
than a fifth the thickness of the binder layer. However, if inorganic fine 
particles having an average particle diameter smaller than a fifth the 
thickness of the binder layer are used, the amount of the particles to be 
used becomes considerably great for satisfying the effect to fully exhibit 
the present invention, i.e., the feeding property to smoothly move and the 
continuous feeding property. As a result, the transparency of the 
resulting printing medium is lowered (its haze degree is increased) even 
if a transparent film is used as a base material, and so it becomes 
departed from a practicable level as a film for OHP. 
In order to keep this transparency or surface gloss to the practicable 
level, it is necessary to use inorganic fine particles having an average 
particle diameter not smaller than a fifth the thickness of the binder 
layer. 
As the most preferred embodiment in the present invention, may be mentioned 
the use of inorganic fine particles greater than the thickness of the 
binder layer. 
The content of these inorganic fine particles in the binder layer is 
preferably of the order of 0.05 to 3 parts per 100 parts of the binder 
component in terms of solids. If this content is lower than 0.05 part, the 
effects according to the present invention are not fully exhibited. On the 
other hand, any content exceeding 3 parts is rendered transparency or 
surface gloss lower. 
No particular limitation is imposed on a resin used as the binder layer so 
far as it can receive the so-called water-based ink and shows solubility 
in or affinity for the water-based ink. Examples of such a resin include 
water-soluble resins, for example, synthetic resins such as polyvinyl 
pyrrolidone, polyvinyl alcohol, anionically modified polyvinyl alcohol, 
cationically modified polyvinyl alcohol, polyurethane, 
carboxymethylcellulose, polyester, polyacrylic acid (esters), 
polyacrylamide, hydroxyethylcellulose, hydroxypropylcellulose, melamine 
resins and modified products thereof; and natural resins such as albumin, 
gelatin, casein, starch, cationic starch, gum arabic and sodium alginate, 
to which, however, are not limited. 
In the present invention, a water-dispersible resin (emulsion) may be used 
as the binder layer. As examples of such resins, may be mentioned a great 
number of resins such as polyvinyl acetate, ethylene-vinyl acetate 
copolymers, polystyrene, styrene-(meth)acrylate copolymers, (meth)acrylate 
polymers, vinyl acetate-(meth)acrylic acid (ester) copolymers, 
poly(meth)acrylamide, (meth)acrylamide copolymers, styrene-isoprene 
copolymers, styrene-butadiene copolymers, ethylene-propylene copolymers 
and polyvinyl ether. However, it goes without saying that such resins are 
not limited to these resins. 
Pluralities of these water-soluble resins and water-dispersible resins may 
be used respectively or simultaneously at the same time. 
In a preferred embodiment of the present invention, the binder layer is 
constructed so as to have a structure that resin particles are held in a 
continuous film of a water-soluble resin, particularly, cationically 
modified polyvinyl alcohol. The printing medium having such a structure is 
extremely high in ink absorptivity, can provide bright and sharp dots, is 
excellent in blocking resistance, undergoes scarce changes in the 
performance even under environmental conditions of varied temperatures and 
humidities, can be stably stored for a long period of time, in particular, 
in a high-temperature and high-humidity environment. Further the printing 
medium can form images stable to long-term storage in a high-temperature 
and high-humidity environment, and is excellent in fixing ability and 
stackability after printing. 
More specifically, it is considered that when the cationically modified 
polyvinyl alcohol is contained in the binder layer, the affinity for inks 
having various properties, in particular, for water, or water-miscible 
glycols or glycol ethers is enhanced, and so the ink absorptivity of the 
resulting ink-receiving layer becomes extremely high, whereby an image 
bright and sharp in-dots is provided. In addition, changes in the 
performance become slight even under environmental conditions of varied 
temperatures and humidities. In order to solve the problems of the fixing 
ability, stackability after printing and the like involved in the use of 
the cationically modified polyvinyl alcohol, the above-described aqueous 
resin emulsion is further contained therein. As a result, it is possible 
to markedly improve the above-mentioned performance characteristics so as 
to satisfy the overall performance as a film for OHP. 
The cationically modified product of polyvinyl alcohol (hereinafter 
abbreviated as PVA) useful in the practice of the present invention means 
PVA having a cationic group such as a primary, secondary or tertiary amino 
group, or a quaternary ammonium group. PVA is generally obtained by 
saponifying polyvinyl acetate by the acid saponification or alkali 
saponification. Besides, the cationically modified product of PVA used in 
the present invention, which makes up the printing medium, is obtained by 
a method in which an ordinary PVA is directly cationized with a 
cationizing agent having a cationic group such as 
glycidyltrimethylammonium chloride and a group reactive to the OH group in 
the PVA at the same time, a method in which vinyl acetate and a monomer 
having a reactive group are copolymerized, the resulting copolymer is 
saponified, and the saponified product is then reacted with a cationic 
group-containing compound making good use of such a reactive group to 
obtain a cationically modified PVA, or a method in which a cationic 
monomer is added upon the polymerization of vinyl acetate as a raw 
material to copolymerize them, and the resulting copolymer is saponified 
by a method known per se in the art. 
As cationic monomer used in such copolymerization, may be mentioned 
vinyloxyethyltrimethylammonium chloride, 2,3-dimethyl-1-vinylimidazolium 
chloride, trimethyl-(3-acrylamido-3, 3-dimethylpropyl)ammonium chloride, 
trimethyl-(3-methacrylamidopropyl)ammonium chloride, and primary to 
tertiary amine precursors thereof; 
N-(1,1-dimethyl-3-dimethylaminopropyl)acrylamide, 
N-(3-dimethylaminopropyl)methacrylamide, o-, m- and p-aminostyrenes, and 
monoalkyl and dialkyl derivatives and quaternary ammonium salts thereof; 
o-, m- and p-vinylbenzylamines, and monoalkyl and dialkyl derivatives and 
quaternary ammonium salts thereof; N-(vinylbenzyl)pyrrolidine; 
N-(vinylbenzyl)piperidine; N-vinylpyrrolidone; .alpha.- and 
.beta.-vinylpyridines and quaternary ammonium salts thereof; .alpha.- and 
.beta.-vinylpiperidines and quaternary ammonium salts thereof; 
nitrogen-containing heterocyclic vinyl compounds other than the above, 
such as 2- and 4-vinylquinolines and quaternary ammonium salts thereof, 
and vinyl compound monomers easy to be converted into cationic compounds, 
such as nitro derivatives thereof. Vinyloxyethyl-trimethylammonium 
chloride, 2,3-dimethyl-1-vinyl-imidazolium chloride, 
trimethyl-(3-acrylamido-3,3-dimethylpropyl)ammonium chloride, 
trimethyl-(3-methacrylamidopropyl)ammonium chloride and primary to 
tertiary amine precursors thereof, 
N-(1,1-dimethyl-3-dimethylaminopropyl)acrylamide, and 
N-(3-dimethylamino-propyl)methacrylamide are preferred taking account of 
copolymerizability, stability upon the saponification of an acetate group, 
and the like. 
The amount of cationic groups existing in such a cationically modified PVA 
is preferably within a range of from 0.05 to 30 mole %, more preferably 
from 0.1 to 10 mole % of the total monomer unit in terms of molar fraction 
of monomer units in the polymer. If the existing amount of the cationic 
groups is lower than 0.05 mole %, improving effects on water resistance of 
the ink-receiving layer and ink-jet printing properties such as resolution 
of images and coloring ability are not fully achieved even as compared 
with the case where unmodified PVA is used. On the other hand, if the 
amount exceeds 30 mole %, adhesion of the ink-receiving layer to a base 
material and film-forming property are deteriorated. In addition, the 
compatibility of such a modified PVA with the aqueous resin emulsion, 
which will be described subsequently, is also adversely affected. 
The saponification degree of the PVA used as a backbone polymer is 
preferably 70 to 99 mole %, more preferably 74 to 95 mole %. The 
polymerization degree of the cationically modified PVA is preferably 300 
to 5,000, more preferably 500 to 3,000. In each case, polymers different 
in polymerization degree or saponification degree may be used in 
combination. 
As examples of the aqueous resin emulsion useful in the practice of the 
present invention, may be mentioned, in addition to those mentioned above, 
emulsions of silicone-acrylic copolymers, copolymers containing 
N-methylolacrylamide as units, and copolymers of vinylpyrrolidone and a 
hydrophobic monomer. 
Of these aqueous resin emulsions, the emulsions composed of the copolymers 
of vinylpyrrolidone and a hydrophobic monomer are particularly preferred 
because such a copolymer gives the resulting ink-receiving layer both good 
affinity for inks by the vinylpyrrolidone moiety and high mechanical 
strength of the film and good environmental resistance by the hydrophobic 
monomer moiety, and so the effects of the present invention can be 
achieved. 
As examples of the hydrophobic monomer used, may be mentioned aromatic 
vinyl compounds such as styrene, .alpha.-methylstyrene and 
vinylnaphthalene; esters of (meth)acrylic acid and other unsaturated 
carboxylic acids such as crotonic acid; and vinyl acetate and vinyl 
butyrate. However, no particular limitation is imposed on the hydrophobic 
monomer so far as it is copolymerizable with vinylpyrrolidone. 
Of these, styrene and (meth)acrylic esters are preferred because feeding 
property to various inks, image quality, blocking resistance, stackability 
after printing and the like can be markedly improved at the same time. 
The mixing ratio of vinylpyrrolidone to the hydrophobic monomer is 
preferably within a range of from 1/9to 9/1. The molecular weight of this 
polymer is preferably within a range of from 500 to 1,000,000. 
The content in terms of solids of these aqueous resin emulsions in the 
binder layer is preferably within a range of from 0.1 to 50% by weight, 
more preferably from 1 to 30% by weight based on the content of the 
cationically modified polyvinyl alcohol. If the content is lower than 0.1% 
by weight, the effects of the present invention, i.e., improvements of 
fixing ability, stackability after printing and the like are not fully 
achieved. If the content exceeds 50% by weight on the other hand, the ink 
receptivity of the resulting ink-receiving layer is rapidly lowered, and 
so problems are easy to arise as to image properties, in particular, 
evenness and resistance to bleeding. 
The minimum film-forming temperature (MFT) of the aqueous resin emulsion 
used in the present invention is desirably at least 20.degree. C., 
preferably at least 30.degree. C. More specifically, the use of an aqueous 
resin emulsion having an MFT lower than 20.degree. C. results in an 
ink-receiving layer having a less effect on the improvement of fixing 
ability as compared with the case where an aqueous resin emulsion having 
an MFT of at least 20.degree. C. is used. The reason for this is 
considered to be attributable to the fact that fusion bonding between 
resin particles in the emulsion (hereinafter referred to as emulsion 
particles), and film formation are allowed to overprogress upon formation 
of a film by heating, and so the emulsion particles cannot maintain their 
particle form. Bleeding also becomes somewhat easier to occur compared 
with the case where the aqueous resin emulsion having an MFT of at least 
20.degree. C. is used. 
The size (diameter) of the emulsion particles is preferably smaller than 
the thickness of the ink-receiving layer formed, specifically, not greater 
than 10 .mu.m, preferably not greater than 5 .mu.m. The lower limit of the 
particle size is about 0.01 .mu.m. 
The MFT and particle diameter of the aqueous resin emulsion, the mixing 
ratio of the cationically modified polyvinyl alcohol to the aqueous resin 
emulsion, drying conditions of a coating layer, and the like are suitably 
adjusted, whereby an ink-receiving layer 2 having a structure that resin 
particles 3 are held in a continuous film 4 of the cationically modified 
polyvinyl alcohol, and the inorganic fine particles 5 are partly projected 
from the surface of the coating layer as illustrated in FIG. 1B can be 
formed on a base material 1. 
In the present invention, a composition containing the above-described 
binder components and inorganic fine particles as essential components is 
applied to at least one side of a base material to obtain a printing 
medium having an ink-receiving layer on the surface of the base material. 
Various additives may be mixed in this composition within limits not 
impeding the achievement of the objects of the present invention. 
Specific examples of the additives include various surfactants, dye-fixing 
agents (water-proofings), antifoaming agents, antioxidants, optical 
whitening agents, ultraviolet absorbents, dispersing agents, viscosity 
modifiers, pH adjustors, mildew-proofing agents and plasticizers. These 
additives may be optionally selected from the conventionally-known 
compounds as necessary for the end application intended. 
Another cationic compound may be further contained in the composition with 
a view toward improving shelf stability of images formed. No particular 
limitation is imposed on the cationic compound so far as it contains a 
cationic moiety in its molecule. As examples thereof, may be mentioned 
cationic surfactants of the quaternary ammonium salt type, such as 
monoalkylammonium chlorides, dialkylammonium chlorides, 
tetramethylammonium chloride, trimethylphenylammonium chloride and 
ethylene oxide-added ammonium chlorides, and cationic surfactants of the 
amine salt type. Besides, amphoteric surfactants such as alkylbetaines, 
imidazolinium betaines and alanine derivatives, which contain a cationic 
moiety, may be used. 
As cationic polymers or oligomers, may be mentioned cationically modified 
products of polyacrylamide or copolymers of acrylamide and a cationic 
monomer, polyethyleneimine, polyamide-epichlorohydrin resins, 
polyvinylpyridinium halides, polyamine resin such as polyallylamine, 
polyamine sulfone and polyvinylamine, etc. 
Further, homopolymers of vinylpyrrolidone monomers or their copolymers with 
other common monomers, homopolymers of vinyloxazolidone monomers or their 
copolymers with other common monomers, homopolymers of vinylimidazole 
monomers or their copolymers with other common monomers, etc. may be 
mentioned. The common monomers include methacrylates, acrylates, 
acrylonitrile, vinyl ethers, vinyl acetate, ethylene, styrene and the 
like. 
The content of these cationic compounds in the ink-receiving layer is 
desirably within a range of from 0.01 to 30% by weight based on the 
content of the cationically modified PVA, which is a principal compound 
used in the present invention, in the ink-receiving layer. 
Any content lower than 0.01% by weight results in a printing medium having 
no marked effect on the formation of images stable to long-term storage in 
a high-temperature and high-humidity environment even as compared, with 
the case where no cationic compound is added. Any content exceeding 30% by 
weight results in a printing medium too high in hygroscopicity and easy to 
cause blocking. In addition, its recording surface is low in mechanical 
strength and becomes easy to flaw. 
As the base material constituting the printing medium according to the 
present invention, there may be used a paper web such as wood free paper, 
medium-quality paper, art paper, glossy paper, bond paper, recycled paper, 
baryta paper, cast-coated paper, corrugated fiberboard, nonwoody paper or 
synthetic paper, a film of a plastic such as polyethylene terephthalate, 
diacetate, triacetate, cellophane, celluloid, polycarbonate, polyimide, 
polyvinyl chloride, polyvinylidene chloride, polyacrylate, polyethylene or 
polypropylene, a board of wood such as veneer, the Japanese cypress or 
cedar, a glass plate, ceramics, a plate of a metal such as aluminum, iron 
or copper, a fabric of cotton, rayon, acrylic, nylon, silk, polyester or 
the like, a skin or leather of cattle, sheep, snake, crocodile or the 
like, a synthetic leather, a nonwoven fabric, a rubber-like elastic body, 
mineral paper, or the like. The base material may have either a smooth 
surface or an irregular surface, or be either transparent, translucent or 
opaque. Two or more of these base materials may be laminated on each other 
to be used as the base material. A mat layer, pressure sensitive adhesive 
release layer or the like may be provided on the opposite side of a 
printing surface, or a pressure sensitive adhesive layer may be provided 
on a printing surface after printing. The base material is suitably 
selected from the above-mentioned materials according to various 
conditions such as the intended printing application of the resulting 
printing medium, the use of printed images and the adhesiveness to a 
composition to be coated thereon. In order to obtain a light-transmitting 
printing medium, a transparent plastic film or glass sheet is used as the 
base material, while an opaque plastic film or paper is used as the base 
material for providing a glossy printing medium. 
Upon the preparation of the printing medium according to the present 
invention, the above-described composition is first of all dissolved or 
dispersed, together with other additives if necessary, in water, or an 
alcohol, polyhydric alcohol or another suitable organic solvent to prepare 
a coating formulation. 
The resulting coating formulation is applied to the surface of the base 
material by, for example, a roll coater, blade coater, air knife coater, 
gate roll coater, bar coater, size pressing, spray coating, gravure coater 
or curtain coater method. Thereafter, the thus-coated base material is 
dried using, for example, a hot-air drying oven or heating drum, thereby 
obtaining a printing medium according to the present invention. 
At this time, it is preferable to bake the coating layer at a temperature 
of (the MFT of the aqueous resin emulsion contained+120.degree. C.) or 
lower. If the baking is conducted at a temperature higher than (the 
MFT+120.degree. C.), the resulting printing medium may undergo marked 
deterioration in fixing ability and resistance to bleeding, which is 
considered to be caused by the fact that fusion bonding between the 
emulsion particles, and film formation are allowed to overprogress upon 
the formation of a film by the heating, and so the emulsion particles 
cannot maintain their particle form as described above. 
As needed, the resulting printing medium may be further subjected to 
supercalendering or the like so as to increase the smoothness or surface 
strength of the ink-receiving layer. 
The coat weight of the ink-receiving layer is within a range of from 0.2 to 
50 g/m.sup.2, preferably from 1 to 30 g/m.sup.2 in total. If the coat 
weight is made small, a part of the base material may be exposed without 
coating. Any coat weight less than 0.2 g/m.sup.2 has no improving effect 
on coloring ability of the coating formulation compared with the case 
where no ink-receiving layer is provided. If the coat weight of the 
ink-receiving layer provided exceeds 50 g/m.sup.2 on the other hand, 
curling occurs to a marked extent, particularly, in a low-temperature and 
low-humidity environment. The coat weight may preferably be within a range 
of from 0.5 to 100 .mu.m in terms of thickness. 
When ink-jet printing is conducted on the printing medium described above, 
any known inks may be used with no problem. As recording agents, there may 
be used water-soluble dyes represented by direct dyes, acid dyes, basic 
dyes, reactive dyes and food colors, and besides disperse dyes and 
pigments. They may be used without imposing a particular limitation so far 
as they are those used in the conventional ink-jet printing. Such 
water-soluble dyes, disperse dyes or pigments are used in a proportion of 
0.1 to 20% by weight in ink. 
A solvent suitable for use in water-based inks used in the present 
invention is water or a mixed solvent of water and a water-soluble organic 
solvent. Mixed solvents composed of water and a water-soluble organic 
solvent and containing, as the water-soluble organic solvent, a polyhydric 
alcohol having an effect of inhibiting the drying of the ink are 
particularly preferred. 
A water-miscible glycol or glycol ether may preferably be used as the 
water-soluble organic solvent. 
A preferred method of conducting printing by applying the above-described 
ink to the printing medium described above is an ink-jet printing method. 
As such a method, any system may be used so far as it can effectively 
eject an ink out of an orifice to apply the ink to the printing medium as 
a target. 
In particular, an ink-jet printing system described in Japanese Patent 
Application Laid-Open No. 54-59936, in which an ink undergoes a rapid 
volumetric change by an action of thermal energy applied to the ink, so 
that the ink is ejected out of an orifice by the working force generated 
by this change of state, may be used effectively. 
An illustrative example of an ink-jet printing apparatus, which is suitable 
for use in conducting printing using the printing medium according to the 
present invention, will hereinafter be described. Examples of the 
construction of a head, which is a main component of such an apparatus, 
are illustrated in FIGS. 2, 3 and 4. 
A head 13 is formed by bonding a glass, ceramic or plastic plate or the 
like having a groove 14 through which an ink is passed, to a heating head 
15, which is used for thermal recording (the drawing shows a head to 
which, however, is not limited). The heating head 15 is composed of a 
protective film 16 made of silicon oxide or the like, aluminum electrodes 
17-1 and 17-2, a heating resistor layer 18 made of nichrome or the like, a 
heat accumulating layer 19, and a substrate 20 made of alumina or the like 
having a good heat radiating property. 
An ink 21 comes up to an ejection orifice (a minute opening) 22 and forms a 
meniscus 23 owing to a pressure P. 
Now, upon application of electric signals to the electrodes 17-1, 17-2, the 
heating head 15 rapidly generates heat at the region shown by n to form 
bubbles in the ink 21 which is in contact with this region. The meniscus 
23 of the ink is projected by the action of the pressure thus produced, 
and the ink 21 is ejected from the orifice 22 to a printing medium 25 in 
the form of recording droplets 24. FIG. 4 illustrates an appearance of a 
multi-head composed of an array of a number of heads as shown in FIG. 2. 
The multi-head is formed by closely bonding a glass plate 27 having a 
number of grooves 26 to a heating head 28 similar to the head as 
illustrated in FIG. 2. 
Incidentally, FIG. 2 is a cross-sectional view of the head 13 taken along 
the flow path of the ink, and FIG. 3 is a cross-sectional view taken along 
line 3--3 in FIG. 2. 
FIG. 5 illustrates an example of an ink-jet printing apparatus in which 
such a head has been incorporated. In FIG. 5, reference numeral 61 
designates a blade serving as a wiping member, one end of which is a 
stationary end held by a blade-holding member to form a cantilever. The 
blade 61 is provided at the position adjacent to the region in which a 
printing head operates, and in this embodiment, is held in such a form 
that it protrudes to the course through which the printing head is moved. 
Reference numeral 62 indicates a cap, which is provided at the home 
position adjacent to the blade 61, and is so constituted that it moves in 
the direction perpendicular to the direction in which the printing head is 
moved and comes into contact with the face of ejection openings to cap it. 
Reference numeral 63 denotes an ink-absorbing member provided adjoiningly 
to the blade 61 and, similar to the blade 61, held in such a form that it 
protrudes to the course through which the printing head is moved. The 
above-described blade 61, cap 62 and absorbing member 63 constitute an 
ejection-recovery portion 64, where the blade 61 and absorbing member 63 
remove water, dust and/or the like from the face of the ink-ejecting 
openings. 
Reference numeral 65 designates the printing head having an 
ejection-energy-generating means and serving to eject the ink onto a 
printing medium set in an opposing relation with the ejection opening face 
provided with ejection openings to conduct printing. Reference numeral 66 
indicates a carriage on which the printing head 65 is mounted so that the 
printing head 65 can be moved. The carriage 66 is slidably interlocked 
with a guide rod 67 and is connected (not illustrated) at its part to a 
belt 69 driven by a motor 68. Thus, the carriage 66 can be moved along the 
guide rod 67 and hence, the printing head 65 can be moved from a printing 
region to a region adjacent thereto. 
Reference numerals 51 and 52 denote a paper feeding part from which the 
printing media are separately inserted, and paper feed rollers driven by a 
motor (not illustrated), respectively. With such construction, the 
printing medium is fed to the position opposite to the ejection opening 
face of the printing head, and discharged from a paper discharge section 
provided with paper discharge rollers 53 with the progress of printing. 
In the above constitution, the cap 62 in the head recovery portion 64 is 
receded from the moving course of the printing head 65 when the printing 
head 65 is returned to its home position, for example, after completion of 
printing, and the blade 61 remains protruded to the moving course. As a 
result, the ejection opening face of the printing head 65 is wiped. When 
the cap 62 comes into contact with the ejection opening face of the 
printing head 65 to cap it, the cap 62 is moved so as to protrude to the 
moving course of the printing head. 
When the printing head 65 is moved from its home position to the position 
at which printing is started, the cap 62 and the blade 61 are at the same 
positions as the positions upon the wiping as described above. As a 
result, the ejection opening face of the printing head 65 is also wiped at 
the time of this movement. 
The above movement of the printing head to its home position is made not 
only when the printing is completed or the printing head is recovered for 
ejection, but also when the printing head is moved between printing 
regions for the purpose of printing, during which it is moved to the home 
position adjacent to each printing region at given intervals, where the 
ejection opening face is wiped in accordance with this movement. 
The present invention will hereinafter be described more specifically by 
the following examples. Incidentally, all designations of "part" or 
"parts" and "%" as will be used in the following examples mean part or 
parts by weight and % by weight unless expressly noted. 
EXAMPLE 1 
A composition composed of 100 parts of cationically modified polyvinyl 
alcohol (trade name: CM-318, product of Kuraray Co., Ltd., saponification 
degree: about 89 mole %, polymerization degree: about 1,700, cationization 
degree: about 2 mole %) and 0.7 part, in terms of solids, of finely 
particulate silica (trade name: Sylicia 470, average particle diameter: 12 
.mu.m, product of Fuji Silicia Chemical Co., Ltd.) was dispersed and mixed 
in water as a medium. The thus-obtained coating formulation was applied to 
a polyethylene terephthalate film (thickness: 100 .mu.m, trade name: 
Lumirror, product of Toray Industries, Inc.) using a wire bar to give a 
binder layer having a dry coat thickness of 10 .mu.m. The film thus coated 
was then dried at 120.degree. C. for 3 minutes to prepare a printing 
medium according to the present invention. 
Using inks each having the following compositions, color printing was 
conducted on the printing medium thus obtained under the following 
conditions by means of an ink-jet printing apparatus in which an ink is 
ejected by bubbling of the ink by thermal energy. 
Composition of ink black(Bk)!: 
______________________________________ 
C.I. Direct Black 19 3 parts 
Glycerol 6 parts 
Ethylene glycol 5 parts 
Urea 5 parts 
Isopropyl alcohol 3 parts 
Water 78 parts 
______________________________________ 
Surface tension of ink: about 45 dyne/cm. 
Composition of ink yellow (Y), magenta (M), cyan (C)!: 
______________________________________ 
Dye 4 parts 
Glycerol 7 parts 
Thiodiglycol 7 parts 
Urea 7 parts 
Acetylene glycol 1.5 parts 
Water 73.5 parts 
Surface tension of ink: 
about 35 dyne/cm. 
______________________________________ 
Dye: 
______________________________________ 
Y: C. I. Direct Yellow 86 
M: C. I. Acid Red 23 
C: C. I. Direct Blue 199. 
______________________________________ 
Printing conditions: 
______________________________________ 
Ejection frequency: 4 kHz 
Volume of ejection droplet: 
45 pl 
Printing density: 360 DPI 
Maximum application volume of a single color ink: 
8 nl/mm.sup.2. 
______________________________________ 
EXAMPLE 2 
A printing medium was prepared in exactly the same manner as in Example 1 
except that the finely particulate silica was changed to 0.8 part, in 
terms of solids, of another finely particulate silica, Silbead D-MS 
(average particle diameter: 30 .mu.m, product of Mizusawa Industrial 
Chemicals, Ltd.) to conduct the color printing thereon by means of the 
ink-jet printing apparatus in which an ink is ejected by bubbling of the 
ink by thermal energy. 
EXAMPLE 3 
A printing medium was prepared in exactly the same manner as in Example 1 
except that the finely particulate silica was changed to 0.5 part, in 
terms of solids, of finely particulate alumina, AX-15S (average particle 
diameter: 15 .mu.m, product of Nippon Steel Chemical Co., Ltd.) to conduct 
the color printing thereon by means of the ink-jet printing apparatus in 
which an ink is ejected by bubbling of the ink by thermal energy. 
EXAMPLE 4 
A printing medium was prepared in exactly the same manner as in Example 1 
except that the cationically modified polyvinyl alcohol was changed to 
polyvinyl acetal (trade name: Eslec KW-1, product of Sekisui Chemical Co., 
Ltd.) to conduct the color printing thereon by means of the ink-jet 
printing apparatus in which an ink is ejected by bubbling of the ink by 
thermal energy. 
EXAMPLE 5 
A printing medium was prepared in exactly the same manner as in Example 1 
except that the cationically modified polyvinyl alcohol was changed to 
hydroxyethyl-cellulose (trade name: AL-15, product of Fuji Chemical K.K.) 
to conduct the color printing thereon by means of the ink-jet printing 
apparatus in which an ink is ejected by bubbling of the ink by thermal 
energy. 
EXAMPLES 6 and 7 
Printing media were prepared in exactly the same manner as in Example 1 
except that art paper and wood free paper were respectively used as base 
materials. 
EXAMPLE 8 
A glossy printing medium was prepared in the same manner as in Example 1 
except that a plastic film the surface of which is glossy (trade name: 
Melinex 339, product of ICI Co., Ltd.) was used as the base material and 
that 0.5 part of a polyamine resin (trade name: Sunfix 555, product of 
Sanyo Chemical Industries, Ltd.) was added to the coating formulation. 
Using the obtained printing medium, a color printing was conducted in the 
same manner as in Example 1. 
COMATIVE EXAMPLE 1: 
A printing medium was prepared in exactly the same manner as in Example 1 
except that the finely particulate silica was changed to 0.8 part, in 
terms of solids, of another finely particulate silica, Mizukasil P-705 
(average particle diameter: 1.5 .mu.m, product of Mizusawa Industrial 
Chemicals, Ltd.) to conduct the color printing thereon by means of the 
ink-jet printing apparatus in which an ink is ejected by bubbling of the 
ink by thermal energy. 
COMATIVE EXAMPLE 2: 
A printing medium was prepared in exactly the same manner as in Example 1 
except that the finely particulate silica was changed to 0.6 part, in 
terms of solids, of finely particulate alumina, A-50N (average particle 
diameter: 1.0 .mu.m, product of Nippon Steel Chemical Co., Ltd.) to 
conduct the color printing thereon by means of the ink-jet printing 
apparatus in which an ink is ejected by bubbling of the ink by thermal 
energy. 
COMATIVE EXAMPLE 3: 
A printing medium was prepared in exactly the same manner as in Example 1 
except that the finely particulate silica was changed to 1.0 part, in 
terms of solids, of a finely particulate hygroscopic acrylic resin, Sanwet 
IM-5000SP (average particle diameter: 14 .mu.m, product of Sanyo Chemical 
Industries, Ltd.) to conduct the color printing thereon by means of the 
ink-jet printing apparatus in which an ink is ejected by bubbling of the 
ink by thermal energy. 
COMATIVE EXAMPLE 4: 
A printing medium was prepared in exactly the same manner as in Example 1 
except that the finely particulate silica was changed to 0.5 part, in 
terms of solids, of a finely particulate crosslinked polystyrene resin, 
Fine Pearl PB-3011E (average particle diameter: 11 .mu.m, product of 
Sumitomo Chemical Co., Ltd.) to conduct the color printing thereon by 
means of the ink-jet printing apparatus in which an ink is ejected by 
bubbling of the ink by thermal energy. 
COMATIVE EXAMPLE 5: 
A printing medium was prepared in exactly the same manner as in Example 1 
except that the cationically modified polyvinyl alcohol alone was used in 
a coating formulation to conduct the color printing thereon by means of 
the ink-jet printing apparatus in which an ink is ejected by bubbling of 
the ink by thermal energy. 
COMATIVE EXAMPLE 6: 
A printing medium was prepared in exactly the same manner as in Example 1 
except that the content of the finely particulate silica was changed to 4 
parts in terms of solids to conduct the color printing thereon by means of 
the ink-jet printing apparatus in which an ink is ejected by bubbling of 
the ink by thermal energy. 
COMATIVE EXAMPLE 7: 
A printing medium was prepared in exactly the same manner as in Example 1 
except that the content of the finely particulate silica was changed to 
0.07 part in terms of solids to conduct the color printing thereon by 
means of the ink-jet printing apparatus in which an ink is ejected by 
bubbling of the ink by thermal energy. 
The resulting color print samples were evaluated in the following items. 
Evaluated items! 
(1) Evenness of solid print: 
A black solid print and color solid prints (Y, M, C, R, G and B colors) 
obtained in each example were visually observed either in the form of 
projected images or as they are to evaluate in evenness and rank as C 
where beading clearly occurred, and unevenness was conspicuous, B where 
beading slightly occurred, or A where no beading occurred, and the prints 
were even. 
The beading mentioned in the present invention refers to a phenomenon in 
which dots irregularly move in the plane direction of the surface of an 
ink-receiving layer when ink is still fluid before it is fixed in the 
ink-receiving layer, thus forming new aggregates together with adjacent 
dots to cause an unevenness in the density of printed images. 
(2) Feeding property: 
Ten sheets of the film or paper obtained in each example were continuously 
fed into a printer, BJC-600 (trade name) manufactured by Canon Inc. to 
evaluate it in feeding property and rank as A where smooth feeding was 
feasible, B where paper jam slightly occurred, or C where feeding was 
impossible. 
(3) Continuous feeding property: 
Thirty sheets of the film or paper obtained in each example were set in an 
automatic cut sheet feeder of the printer, BJC-600 (trade name) 
manufactured by Canon Inc. to continuously print a full-color image 
thereon, thereby evaluating it in continuous feeding property and ranking 
as A where smooth printing was feasible, and the sheets of the film or 
paper thus printed underwent no blocking when they are left to stand for 
20 minutes after the printing, B where they underwent slight blocking, or 
C where they underwent complete blocking and were difficult to separate 
from each other. 
(4) OHP suitability: 
The printed image obtained in each example was projected on a screen by an 
OHP, and a projected image formed was visually observed to evaluate it in 
OHP suitability. It was ranked as A where the printed image was high in 
optical density, and the projected image had a clear printed area and was 
high in contrast, bright and easy to read, B where the printed image was 
somewhat low in optical density and the projected image had somewhat dark 
unprinted and printed areas, or C where the printed image was considerably 
low in optical density and the projected image had considerably dark 
unprinted and printed areas and was lacking in definition. 
The evaluation results are shown collectively in Table 1. 
TABLE 1 
______________________________________ 
Evenness of Feeding Continuous OHP 
solid print property feeding property 
suitability 
______________________________________ 
Ex. 1 A A A A 
Ex. 2 A A A A 
Ex. 3 A A A A 
Ex. 4 A A A A 
Ex. 5 B A A B 
Ex. 6 A A A -- 
Ex. 7 A A A -- 
Ex. 8 A A A -- 
Comp. A B C A 
Ex. 1 
Comp. A B C A 
Ex. 2 
Comp. B C C A 
Ex. 3 
Comp. A B C A 
Ex. 4 
Comp. A C C A 
Ex. 5 
Comp. B A A C 
Ex. 6 
Comp. A C C A 
Ex. 7 
______________________________________ 
EXAMPLE 9 
A composition composed of 100 parts of cationically modified polyvinyl 
alcohol (trade name: CM-318, product of Kuraray Co., Ltd., saponification 
degree: about 89 mole %, polymerization degree: about 1,700, cationization 
degree: about 2 mole %), 20 parts, in terms of solids, of an aqueous 
emulsion of a styrene-acrylate copolymer (trade name: Movinyl 970, product 
of Hoechst Gosei K.K., solids: 40%, MFT: 100.degree. C.) and 0.7 part, in 
terms of solids, of finely particulate silica (Sylicia 470) was dispersed 
and mixed in water as a medium. The thus-obtained coating formulation was 
applied to a polyethylene terephthalate film (thickness: 100 .mu.m, trade 
name: Lumirror, product of Toray Industries, Inc.) using a wire bar to 
give a dry coat thickness of 10 .mu.m. The film thus coated was then dried 
at 120.degree. C. for 3 minutes to prepare a printing medium according to 
the present invention. 
Using the inks each having the compositions described in Example 1, color 
printing was conducted on the printing medium thus obtained under the same 
conditions as those in Example 1 by means of the ink-jet printing 
apparatus in which an ink is ejected by bubbling of the ink by thermal 
energy. 
EXAMPLE 10 
A printing medium was prepared in exactly the same manner as in Example 9 
except that the content of the aqueous emulsion of the styrene-acrylate 
copolymer was changed to 5 parts in terms of solids to conduct evaluation 
in the same manner as in Example 9. 
EXAMPLE 11 
A printing medium was prepared in exactly the same manner as in Example 9 
except that the content of the aqueous emulsion of the styrene-acrylate 
copolymer was changed to 10 parts in terms of solids to conduct evaluation 
in the same manner as in Example 9. 
EXAMPLE 12 
A printing medium was prepared in exactly the same manner as in Example 9 
except that the content of the aqueous emulsion of the styrene-acrylate 
copolymer was changed to 40 parts in terms of solids to conduct evaluation 
in the same manner as in Example 9. 
EXAMPLE 13 
A printing medium was prepared in exactly the same manner as in Example 9 
except that the aqueous emulsion of the styrene-acrylate copolymer was 
changed to an aqueous emulsion of a methacrylate copolymer (trade name: 
Primal B-88, product of Rohm and Hass Co., solids: 42%, MFT: 90.degree. 
C.) to conduct evaluation in the same manner as in Example 9. 
EXAMPLE 14 
A printing medium was prepared in exactly the same manner as in Example 9 
except that the aqueous emulsion of the styrene-acrylate copolymer was 
changed to an aqueous emulsion of an acrylate copolymer (trade name: 
Movinyl 742N, product of Hoechst Gosei K.K., solids: 46%, MFT: 50.degree. 
C.) to conduct evaluation in the same manner as in Example 9. 
EXAMPLE 15 
A printing medium was prepared in exactly the same manner as in Example 9 
except that the cationically modified polyvinyl alcohol was changed to 
another cationically modified polyvinyl alcohol (trade name: C-506, 
product of Kuraray Co., Ltd., saponification degree: about 74 to 80 mole 
%, polymerization degree: about 500, cationization degree: about 1 mole %) 
to conduct evaluation in the same manner as in Example 9. 
EXAMPLE 16 
A printing medium was prepared in exactly the same manner as in Example 13 
except that the cationically modified polyvinyl alcohol was changed to the 
cationically modified polyvinyl alcohol used in Example 15 to conduct 
evaluation in the same manner as in Example 9. 
EXAMPLE 17 
A printing medium was prepared in exactly the same manner as in Example 14 
except that the cationically modified polyvinyl alcohol was changed to the 
cationically modified polyvinyl alcohol used in Example 15 to conduct 
evaluation in the same manner as in Example 9. 
EXAMPLE 18 
A printing medium was prepared in exactly the same manner as in Example 9 
except that the aqueous emulsion of the styrene-acrylate copolymer was 
changed to an aqueous emulsion of an acrylate copolymer (trade name: 
Movinyl 950, product of Hoechst Gosei K.K., solids: 41%, MFT: 0.degree. 
C.) to conduct evaluation in the same manner as in Example 9. 
EXAMPLE 19 
A printing medium was prepared in exactly the same manner as in Example 9 
except that the aqueous emulsion of the styrene-acrylate copolymer was 
changed to an aqueous emulsion of an acrylate copolymer (trade name: 
Primal AC-388, product of Rohm and Hass Co., solids: 50%, MFT: 8.degree. 
C.) to conduct evaluation in the same manner as in Example 9. 
EXAMPLES 20 and 21 
Printing media were prepared in the same manner as in Example 9 except that 
art paper and wood free paper were respectively used as base materials to 
conduct evaluation in the same manner as in Example 9. 
EXAMPLES 22 and 23 
Printing media were prepared in the same manner as in Example 9 except that 
a white PET film (thickness: 100 .mu.m, trade name: White Lumirror, 
product of Toray Industries, Inc.) and a translucent PET film (thickness: 
100 .mu.m, trade name: Lumimat, product of Toray Industries, Inc.) were 
respectively used as base materials. 
EXAMPLES 24 and 25 
Printing media were prepared in the same manner as in Example 9 except that 
an aluminum plate and a copper plate were respectively used as base 
materials. 
EXAMPLE 26 
A printing medium was prepared in the same manner as in Example 9 except 
that cotton cloth was used as a base material. 
EXAMPLE 27 
A printing medium was prepared in the same manner as in Example 9 except 
that cowhide was used as a base material, and the periphery of the cowhide 
was fixed to a frame so as not to shrink upon its drying. 
EXAMPLE 28 
A printing medium was prepared in the same manner as in Example 22 except 
that a pressure sensitive adhesive release layer was provided on one side 
of the base material. 
Evaluated items! 
(1) Evenness of solid print: 
Evaluation was conducted in the same manner as that in Example 1. 
(2) Bleeding between black and color inks: 
The resistance to bleeding was ranked as C where bleeding clearly occurred 
at boundaries between a black printed area and color printed areas (Y, M, 
C, R, G and B), B where bleeding slightly occurred, or A where no bleeding 
occurred. 
(3) Fixing ability: 
After full dot printing was conducted with two inks of a black color and a 
yellow, cyan or magenta color in an environment of 25.degree. C./60% RH, 
and the resulting prints were left over for 2 minutes, sheets of NP-DRY 
paper (product of Canon Inc.) were separately laid on two full dot printed 
areas with the black ink and the color ink (i.e., yellow, cyan or magenta 
ink) to rub the printed areas with the NP-DRY paper under a pressure of 4 
Kg/cm.sup.2. The fixing ability was ranked as C where the inks clearly 
transferred to the paper when the paper was released, and the printed 
areas were clearly scratched, B where slight transfer was recognized, and 
the printed areas were scratched a little, or A where neither transfer nor 
scratch was recognized. 
(4) Stackability after printing: 
Printing was continuously conducted using A4-sized printing media, and the 
resulting prints were stacked one after another. The stackability after 
printing was ranked as C where a defect in image was clearly recognized 
due to the stack, B where a minor defect was recognized, or A where no 
defect was recognized. 
(5) OHP suitability: 
Evaluation was conducted in the same manner as that in Example 1. 
(6) Shelf stability of printed image: 
After printing was conducted on each printing medium by means of the 
above-described printer, and the resulting print was stored for 7 days in 
an environment of 35.degree. C./90% RH, the shelf stability of image was 
evaluated in comparison with the image before the storage and ranked as C 
where ink running, exudation and dot gain occurred, so that image quality 
was remarkably poor compared with the image before the storage, A where no 
change was recognized, or B where it was in-between thereof. 
The evaluation results are shown collectively in Table 2. 
TABLE 2 
__________________________________________________________________________ 
Evenness of Bleeding 
solid print between Bk 
Fixing ability 
Stackability 
OHP Shelf stability 
Bk area Color area 
and color ink 
Bk area 
Color area 
after printing 
suitability 
of print 
__________________________________________________________________________ 
Ex. 9 
A A A A A A A A 
Ex. 10 
A A A A A A A A 
Ex. 11 
A A A A A A A A 
Ex. 12 
A A B B A A A A 
Ex. 13 
A A A A A A A A 
Ex. 14 
A A A A A A A A 
Ex. 15 
A A A A A A A A 
Ex. 16 
A A A A A A A A 
Ex. 17 
A A A A A A A A 
Ex. 18 
B A B B B A B A 
Ex. 19 
B A B B B A B A 
Ex. 20 
A A A A A A -- A 
Ex. 21 
A A A A A A -- A 
Ex. 22 
A A A A A A -- A 
Ex. 23 
A A A A A A -- A 
Ex. 24 
A A A A A A -- A 
Ex. 25 
A A A A A A -- A 
Ex. 26 
A A A A A A -- A 
Ex. 27 
A A A A A A -- A 
Ex. 28 
A A A A A A -- A 
__________________________________________________________________________ 
EXAMPLE 29 
A composition composed of 100 parts of cationically modified polyvinyl 
alcohol (trade name: CM-318, product of Kuraray Co., Ltd., saponification 
degree: about 89 mole %, polymerization degree: about 1,700, cationization 
degree: about 2 mole %), 20 parts, in terms of solids, of a 
vinylpyrrolidone-styrene copolymer (trade name: Antara 430, product of ISP 
Japan K.K., solids: 40%) and 0.8 part, in terms of solids, of finely 
particulate silica (Silbead D-MS) was dispersed and mixed in water as a 
medium. The thus-obtained coating formulation was applied to a 
polyethylene terephthalate film (thickness: 100 .mu.m, trade name: 
Lumirror, product of Toray Industries, Inc.) using a wire bar to give a 
dry coat thickness of 10 .mu.m. The film thus coated was then dried at 
120.degree. C. for 3 minutes to prepare a printing medium according to the 
present invention. 
Using the inks each having the compositions described in Example 1, color 
printing was conducted on the printing medium thus obtained under the same 
conditions as those in Example 1 by means of the ink-jet printing 
apparatus in which an ink is ejected by bubbling of the ink by thermal 
energy. 
EXAMPLE 30 
A printing medium was prepared in the same manner as in Example 29 except 
that the content of the vinylpyrrolidone-styrene copolymer was changed to 
5 parts in terms of solids to conduct the color printing. 
EXAMPLE 31 
A printing medium was prepared in the same manner as in Example 29 except 
that the content of the vinylpyrrolidone-styrene copolymer was changed to 
100 parts in terms of solids to conduct the color printing in the same 
manner as in Example 29. 
EXAMPLE 32 
A printing medium was prepared in the same manner as in Example 29 except 
that the content of the vinylpyrrolidone-styrene copolymer was changed to 
300 parts in terms of solids to conduct the color printing. 
EXAMPLE 33 
A printing medium was prepared in the same manner as in Example 29 except 
that the vinylpyrrolidone-styrene copolymer was changed to a 
vinylpyrrolidone-ethyl acrylate copolymer (trade name: Antara 130, product 
of ISP Japan K.K., solids: 40%) to conduct the color printing. 
EXAMPLE 34 
A printing medium was prepared in the same manner as in Example 29 except 
that the cationically modified polyvinyl alcohol was changed to another 
cationically modified polyvinyl alcohol (trade name: C-506, product of 
Kuraray Co., Ltd., saponification degree: about 74 to 80 mole %, 
polymerization degree: about 500, cationization degree: about 1 mole %) to 
conduct the color printing. 
EXAMPLE 35 
A printing medium was prepared in the same manner as in Example 29 except 
that the cationically modified polyvinyl alcohol was changed to unmodified 
polyvinyl alcohol (trade name: PVA217, product of Kuraray Co., Ltd., 
saponification degree: about 88 mole %, polymerization degree: about 
1,700) to conduct the color printing. 
EXAMPLE 36 
A printing medium was prepared in the same manner as in Example 29 except 
that the cationically modified polyvinyl alcohol was changed to polyvinyl 
acetal (trade name: KW-1, product of Sekisui Chemical Co., Ltd.) to 
conduct the color printing. 
EXAMPLE 37 
A printing medium was prepared in the same manner as in Example 29 except 
that the cationically modified polyvinyl alcohol was changed to 
hydroxyethylcellulose (trade name: AL-15, product of Fuji Chemical K.K.) 
to conduct the color printing. 
EXAMPLE 38 
A printing medium was prepared in the same manner as in Example 29 except 
that the cationically modified polyvinyl alcohol was changed to 
polyethylene oxide (trade name: Alkox R-1000, product of Meisei Chemical 
Works, Ltd.) to conduct the color printing. 
EXAMPLE 39 
A printing medium was prepared in the same manner as in Example 29 except 
that the vinylpyrrolidone-styrene copolymer was changed to a 
vinylpyrrolidone-vinyl acetate copolymer (trade name: S360, product of ISP 
Japan K.K.) to conduct the color printing. 
EXAMPLES 40 and 41 
Printing media were prepared in the same manner as in Example 29 except 
that art paper and wood free paper were respectively used as base 
materials to conduct the color printing. 
Evaluated items! 
Evaluation was conducted as to the same items (1) to (6) as those described 
in Example 9. Further, evaluation as to haze degree of film was added. 
(7) Haze degree of film: 
An image obtained by printing on each printing medium sample by means of 
the printer described above was projected by a transmission type OHP, 
thereby evaluating it in haze degree and ranking as C where haze developed 
and the projected image was dark, A where no problem occurred, or B where 
the projected image was somewhat dark. 
The evaluation results are shown collectively in Table 3. 
TABLE 3 
__________________________________________________________________________ 
Evenness of Bleeding Shelf 
Haze 
solid print between Bk 
Fixing ability 
Stackability 
OHP stability 
degree 
Bk area Color area 
and color ink 
Bk area 
Color area 
after printing 
suitability 
of print 
of film 
__________________________________________________________________________ 
Ex. 29 
A A A A A A A A A 
Ex. 30 
A A A A A A A A A 
Ex. 31 
A A A A A A A A A 
Ex. 32 
A A A A A A A A A 
Ex. 33 
A A A A A A A A A 
Ex. 34 
A A A A A A A A A 
Ex. 35 
B A B A B A A B A 
Ex. 36 
B A B A A A A B A 
Ex. 37 
B A A A A A A B A 
Ex. 38 
A A B A A A B B B 
Ex. 39 
A B B A A A A B A 
Ex. 40 
A A A A A A -- B A 
Ex. 41 
A A A A A A -- B A 
__________________________________________________________________________ 
Further, the printing media prepared in Examples 9 through 40 had the same 
feeding property and continuous feeding property as shown in Examples 1 
through 8. 
According to the present invention, as described above, there can be 
provided printing media which are excellent in ink absorptivity to a 
variety of inks having various properties, provide dots bright and high in 
optical density, can form high-definition images excellent in evenness and 
free of bleeding, and besides are excellent in feeding property and 
continuous feeding property in various printers and also superb in 
transparency. 
According to the present invention, there can also be provided printing 
media having, in addition to the above-described effects, ideal 
performance requirements that ink fixing ability and stackability after 
printing are excellent, and shelf stability of images formed is also 
excellent, and so the images undergo no deterioration even when left to 
stand for a long period of time in a high-temperature and high-humidity 
environment. 
While the present invention has been described with respect to what is 
presently considered to be the preferred embodiments, it is to be 
understood that the invention is not limited to the disclosed embodiments. 
To the contrary, the invention is intended to cover various modifications 
and equivalent arrangements included within the spirit and scope of the 
appended claims. The scope of the following claims is to be accorded to 
the broadest interpretation so as to encompass all such modifications and 
equivalent structures and functions.