Polymer scale preventive process using a coating of chitosan salt and phenothiazine

A polymer scale preventive process for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising (A) a water-soluble basic polysaccharide and (B) a phenothiazine. The process is used for forming a coating on the inner wall, etc. of a polymerization vessel, and highly safe for operators. Deposition of polymer scale can be effectively prevented, and polymeric product with high whiteness or a low initial coloration is obtained.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a polymer scale preventive agent useful in 
polymerization of a monomer having an ethylenically unsaturated double 
bond, a polymerization vessel effective in preventing polymer scale 
deposition, and a process of producing polymer using said vessel. 
2. Description of the Prior Art 
In processes of preparing polymers by polymerizing a monomer in a 
polymerization vessel, the problem that polymer deposits on the inner wall 
surface and so forth in the form of scale, is known. The deposition of the 
polymer scale on the inner wall results in disadvantages that the yield of 
the polymer and cooling capacity of the polymerization vessel are lowered; 
that the polymer scale may peel and mix into a polymeric product, thereby 
impairing the quality of the polymeric product; and that removal of such 
polymer scale is laborious and hence time-consuming. Further, since the 
polymer scale contains unreacted monomers and operators may be exposed 
thereto, which may cause physical disorders in the operators. 
Heretofore, as methods for preventing polymer scale deposition on the inner 
wall surface and so forth of a polymerization vessel in polymerization of 
a monomer having an ethylenically unsaturated double bond, methods in 
which substances exemplified below are coated on the inner wall surface, 
etc. as a scale preventive agent, have been known. 
For example, particular polar organic compounds (Japanese Patent 
Publication (KOKOKU) No.45-30343(1970)), a dye or pigment (Japanese Patent 
Publication (KOKOKU) Nos.45-30835(1970) and 52-24953(1977)), an aromatic 
amine compound (Japanese Pre-examination Patent Publication (KOKAI) 
No.51-50887(1976)) and a reaction product of a phenolic compound and an 
aromatic aldehyde (Japanese Pre-examination Patent Publication (KOKAI) 
No.55-54317(1980)) are disclosed. 
In the meantime, vinyl chloride polymers obtained by polymerization are 
required to have a good whiteness. That is, when polymeric products such 
as vinyl chloride polymers are formed or molded with no addition of a 
coloring agent, the resulting formed or molded product is colored more or 
less. This coloration is called initial coloration, which is required to 
be as low as possible. Specifically, for example, the formed or molded 
products are required to have an L value according to the Hunter's color 
difference equation, described in JIS Z 8730 (1980), of 70 or more. 
The prior art polymer scale preventive agents generally include a great 
number of colored substances as exemplified typically by the dyes and 
pigments described in Japanese Patent Publication (KOKOKU) 
Nos.45-30835(1970) and 52-24953(1977), the aromatic amine compounds 
described Japanese Pre-examination Patent Publication (KOKAI) 
No.51-50887(1976), and the reaction products of a phenolic compound and an 
aromatic aldehyde described in Japanese Pre-examination Patent Publication 
(KOKAI) No.55-54317(1980). Presumably, for this, a colored polymer is 
obtained in suspension polymerization and the like of vinyl chloride, etc. 
in a polymerization vessel which has a coating comprising the polymer 
scale preventive agent described above formed on its inner wall. That is, 
according to measurement of the lightness L described above, the L may be 
measured to be 65 or less, and coloration is thereby confirmed. 
Presumably, the coloration is caused by incorporation of components of the 
coating which has dissolved or peeled into the polymerization mass. 
Improvement is required for producing a polymer of high quality. 
Moreover, the prior art polymer scale preventive agents generally include 
poisonous substances as exemplified typically by terrible substances such 
as aniline, nitrobenzene, formaldehyde, etc. among the polar compounds 
described in Japanese Patent Publication (KOKOKU) No.45-30343(1970), and 
pigments containing a heavy metal such as chromium or lead among the 
pigments described in Japanese Patent Publication (KOKOKU) 
No.45-30835(1970). The dyes described in Japanese Patent Publication 
(KOKOKU) Nos.45-30835(1970) and 52-24953(1977) include some dyes that 
involve concern about carcinogenesis. Therefore, use of these substances 
may cause problems in safety of operators. 
In the U.S. patent application Ser. No. 07/705,554 filed on May 24, 1991 by 
T. Shimizu et al., now U.S. Pat. No. 5,153,281 is disclosed a polymer 
scale preventive agent, as one which is safe and effective in producing 
polymeric products with a low initial coloration, comprising a 
water-soluble basic polysaccharide such as chitosans. The present 
invention relates to an improvement of the agent above described in the 
U.S. application in prevention of polymer scale deposition. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a polymer scale preventive 
agent which is capable of preventing polymer scale deposition effectively, 
puts no color to a polymeric product to thereby produce the polymeric 
product with a low initial coloration, and are not poisonous and therefore 
causes no concern with respect to safety or sanitation, a polymerization 
vessel effective in preventing polymer scale deposition using the same 
preventive agent, and a process of producing a polymer using the 
polymerization vessel. 
Thus, the present invention provides, as a means of attaining said object, 
a polymer scale preventive agent for use in polymerization of a monomer 
having an ethylenically unsaturated double bond, comprising: 
(A) a water-soluble basic polysaccharide, and 
(B) a phenothiazine. 
Further the present invention provides a polymerization vessel having on 
its inner wall surfaces a coating preventing deposition of polymer scale, 
wherein said coating comprises the components (A) and (B) above. 
Furthermore, the present invention provides a process of producing a 
polymer by polymerization of a monomer having an ethylenically unsaturated 
double bond in a polymerization vessel, comprising the step of carrying 
out said polymerization in said polymerization vessel having on its inner 
surfaces, the coating comprising the components (A) and (B), whereby the 
deposition of polymer scale is prevented. 
According to the present invention, polymers with an L value of 70 or more, 
which has a low initial coloration or a high whiteness, can be prepared. 
Moreover, the scale preventive agent used in the present invention is not 
poisonous and is highly safe; hence there is no problem about safety or 
sanitation of operators. 
Further, according to the present invention, polymer scale deposition can 
be effectively prevented, irrespectively of polymerization conditions such 
as the kind of a monomer or a polymerization initiator, polymerization 
type, the kind of material constituting the inner wall of polymerization 
vessels, etc. 
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Polymer scale preventive agent 
(A) Water-soluble basic polysaccharide 
The water-soluble basic polysaccharide used in the present invention 
includes, for example, chitosans, water-soluble chitosan derivatives, 
polygalactosamines, water-soluble polygalactosamine derivatives and 
water-soluble chitin derivatives. 
Chitosans are a straight chain polysaccharide, i.e., 
poly-1,4-.beta.-glucosamine, formed by polymerization through .beta.-1,4 
linkage of D-glucosamine. It can be obtained by deacetylization of chitin 
contained in the carapace of the Crustacea such as prawns, shrimps and 
crabs. Recently a chitosan can be produced by culturing a mold, and the 
chitosan thus produced can be used in the same manner as those naturally 
occurring. The chitosans are insoluble in water under the neutral 
conditions, but soluble under the acidic conditions; hence the chitosans 
are used under a pH of less than 7. 
The water-soluble chitosan derivatives which may be used in the present 
invention include the following: 
(1) Organic acid salts and inorganic acid salts of chitosans. The organic 
acid specifically includes, for example, acetic acid, glycollic acid, 
malic acid, citric acid, and ascorbic acid. The inorganic acid includes, 
for example, hydrochloric acid, sulfuric acid, nitric acid and phosphoric 
acid. Chitosans preferably have a deacetylization degree of 40 to 100%. 
(2) Water-soluble low molecular products obtained by decomposition of 
chitosans, i.e., water-soluble glucosamine oligomers. Normally, 5 to 
20-mers of glucosamine are preferred. Such oligomers can be produced by 
conventional depolymerization methods, for example, the hydrochloric acid 
hydrolysis method (Japanese pre-examination patent publication(KOKAI) No. 
61-21102(1986), the nitrate decomposition method (Japanese pre-examination 
patent publication (KOKAI) No. 62-184002(1987), the chlorine decomposition 
method (Japanese pre-examination patent publication (KOKAI) No. 
60-186504(1985), the phosphoric acid decomposition method and 
decomposition methods using an enzyme or microorganism. 
(3) Water-soluble derivatives of chitosans prepared by introducing a 
hydrophilic group thereinto. Examples are described in Japanese 
pre-examination patent publication (KOKAI) No. 63-14714(1988) and include 
polyoxyethylene chitosans, polyoxypropylene chitosans, phosphated 
chitosans, N-glycidyltrimethylammonium chitosans, dihydropropylchitosans, 
glycol chitosan and methylglycol chitosan. 
The polygalactosamines which may be used in the present invention are 
insoluble in water under neutral conditions, but soluble under a pH of 7 
or less and therefore used under such conditions. Polygalactosamines can 
be produced by culturing a mold (APPLICATION OF CHITIN AND CHITOSAN 
pp.24-26, Edited by Society for Research of Chitin and Chitosan, 1990, 
published by Giho-do Shuppan). 
The water-soluble polygalactosamine derivatives include the following: 
(1) Organic acid salts and inorganic acid salts of polygalactosamines 
including salts of organic acids such as acetic acid, formic acid or the 
like, and salts of inorganic acids such as hydrochloric acid, nitric acid 
or the like; 
(2) Water-soluble low molecular products obtained by decomposition of 
polygalactosamines. Normally, 5 to 20-mers of galactosamine are preferred. 
Such oligomers can be produced by decomposition methods using an enzyme or 
microorganism. 
The water-soluble chitin derivatives which may be used in the present 
invention, include the following: 
(1) Water-soluble N-acetylglucosamine oligomers obtained by decomposition 
of chitins. Normally, 5 to 20-mers are preferred. Such oligomers can be 
produced by conventional depolymerization methods, for example, the 
nitrous acid decomposition method, the formic acid decomposition method, 
the chlorine decomposition method (Japanese pre-examination patent 
publication (KOKAI) No. 60-186504(1987)) or decomposition methods using an 
enzyme (e.g., chittinase) or a microorganism. 
(2) Water soluble derivatives of chitins prepared by introducing a 
hydrophilic group thereinto. Examples are described in Japanese 
pre-examination patent publication (KOKAI) No. 63-14714(1988) and include 
polyoxyethylene chitins, polyoxypropylene chitins, phosphated chitins and 
dihydropropylchitins. 
Among the water-soluble basic polysaccharides described above, preferred 
are the inorganic acid salts and organic acid salts of chitosans, having a 
deacetylization degree of 65% or more and a viscosity at 20.degree. C. in 
the form of an aqueous solution containing 0.5% by weight of the chitosan 
and 0.5% by weight of acetic acid of 30 cP or more when measured with a 
B-type viscometer, and the organic or inorganic salts of 
polygalactosamines with a molecular weight of 10,000 or more. 
The water-soluble basic polysaccharides may be used singly or in 
combination of two or more. 
(B) Phenothiazine 
The phenothiazine, the component (B) of the polymer scale preventive agent 
of the present invention, is typically represented by, for example, the 
following general formula: 
##STR1## 
wherein R may be the same or different where there exist two or more R's 
and each represent a hydrogen atom, --OH, --Cl, --CH.sub.3, --C.sub.2 
H.sub.5, --COCH.sub.3, --COC.sub.2 H.sub.5, --SO.sub.2 CH.sub.3, 
--SO.sub.2 C.sub.2 H.sub.5, or --NO.sub.2, and n is an integer of 1 to 4, 
preferably 1 or 2. 
The examples of the phenothiazine include phenothiazine, 
2-acetylphenothiazine, 2-propylphenothiazine, 2-nitrophenothiazine, 
2-methylsulfonylphenothiazine, 3,7-dihydroxyphenothiazine, 
3,7-diaminophenothiazine, 3-chlorophenothiazine and the like. 
The preferred combinations of the components (A) and (B) include those 
specifically described in Examples later. 
The amount of the phenothiazine (B) in the polymer scale preventive agent 
of the present invention ranges normally from 0.1 to 1,000 parts by 
weight, preferably 1 to 600 parts by weight, per 100 parts by weight of 
the component (A). If the amount of the phenothiazine (B) is too small or 
too large relative to the component (A), improvement in scale preventing 
effect due to the combined use of the components (A) and (B) is hardly 
attained. 
Other components 
To the scale preventive agent, for example, a solvent, a cationic 
surfactant, a nonionic surfactant, an anionic surfactant, and so forth can 
be optionally added as long as the scale preventing effect is not 
impaired. 
Further, inorganic compounds can be optionally added to the coating liquid 
as long as the high whiteness, safety or the scale preventing effect is 
not impaired. The inorganic compounds which may be added include, for 
example, silicic acids or silicates such as orthosilicic acid, metasilicic 
acid, mesodisilicic acid, mesotrisilicic acid, mesotetrasilicic acid, 
sodium metasilicate, sodium orthosilicate, sodium disilicate, sodium 
tetrasilicate and water glass; metallic salts such as oxygen acid salts, 
acetates, nitrates, hydroxides or halides of a metal selected from alkali 
earth metals such as magnesium, calcium, and barium, zinc family metals 
such as zinc, aluminum family metals such as aluminum, and platinum family 
metals such as ruthenium, rhodium, palladium, osmium, iridium and 
platinum; and inorganic colloids such as ferric hydroxide colloid, 
colloidal silica, colloid of barium sulfate, and colloid of aluminum 
hydroxide. The abovementioned inorganic colloids may be those prepared, 
for example, by mechanical crushing, irradiation with ultrasonic wave, 
electrical dispersion or chemical methods. 
The polymer scale preventive agent is used for forming a coating, for 
example, on the inner wall surfaces of a polymerization vessel, so that 
scale deposition in the vessel can be prevented. Normally, in forming said 
coating on the inner wall surfaces, etc. of a polymerization vessel, the 
polymer scale preventive agent is used in a liquid state, i.e., as a 
coating liquid. 
Preparation of a coating liquid 
The coating liquid mentioned above is prepared by dissolving-or dispersing 
said components (A) and (B) in a solvent. 
The solvents used for preparation of the coating liquid include, for 
example, water; alcohols such as methanol, ethanol, propanol, butanol, 
2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 3-methyl-1-butanol, 
2-methyl-2-butanol, 2-pentanol, etc.; ketones such as acetone, methyl 
ethyl ketone, methyl isobutyl ketone, etc.; esters such as methyl formate, 
ethyl formate, methyl acetate, methyl acetoacetate, etc.; ethers such as 
4-methyldioxolane, ethylene glycol diethyl ether, etc.; furans; and 
aprotic solvents such as dimethylformamide, dimethyl sulfoxide, 
acetonitrile, etc. These solvents may be used singly or as a mixed solvent 
of two or more thereof as appropriate. 
The total concentration of the components (A) and (B) is not limited as 
long as the coating weight described later can be obtained, and it is 
normally in the range from 0.005 to 10% by weight, preferably from 0.01 to 
5% by weight. The Ph of the coating liquid is not particularly limited. 
Asuitable acid or alkali may be used for adjusting the pH. 
Formation of coating 
When the coating liquid prepared as described above is used for forming a 
coating on the inner wall surface of a polymerization vessel, first, the 
coating liquid is applied to the inner wall surface and then dried 
sufficiently, e.g., at a temperature of room temperature to 100.degree. 
C., followed by washing with water if necessary. A coating is formed by 
these operations on the inner wall surface of the polymerization vessel; 
hence the polymer scale deposition thereon can be prevented. 
The above-mentioned coating is preferably formed on not only the inner wall 
surfaces of a polymerization vessel but also other parts with which the 
monomer comes into contact during polymerization. For example, it is 
preferred to form the coating by applying said coating liquid on a 
stirring shaft, stirring blades, baffles, condensers, headers, search 
coil, bolts, nuts, etc. 
More preferably, the coating is formed on not only the parts with which the 
monomer comes into contact during polymerization but also other parts on 
which polymer scale may deposit, for example, such as the inner surfaces 
of equipment and tubing of recovery system for unreacted monomer. These 
parts, more specifically, are exemplified by the inner wall surfaces of 
monomer distillation columns, condensers, monomer stock tanks and valves, 
etc. in said recovery system. 
The method of applying the coating liquid on the inner wall surface, etc. 
of a polymerization vessel is not particularly limited, and includes, for 
example, the brush coating, spray coating, the method of filing the 
polymerization vessel, etc. with the coating liquid followed by withdrawal 
thereof, and automatic coating methods as disclosed in Japanese 
Pre-examination Patent Publication (KOKAI) Nos.57-61001(1982) and 
55-36288(1980), and Japanese Patent Publication (KOHYO) 
Nos.56-501116(1981) and 56-501117(1981), and Japanese Pre-examination 
Publication (KOKAI) No.59-11303(1984), etc. 
The method of drying wet coated surface provided by application of the 
coating liquid, is not limited, either. The drying is conducted preferably 
at a temperature within the range from room temperature to 100.degree. C., 
typically 30.degree. C. to 80.degree. C. Specifically, a method in which, 
after the liquid is applied, hot air with a suitable elevated temperature 
is blown to the coated surface, and a method in which the inner wall 
surface of a polymerization vessel and the surfaces of other parts to be 
coated are previously heated at, e.g., 30.degree.-80.degree. C. and the 
coating liquid is directly applied to the heated surfaces, etc. After 
dried, the coated surfaces are washed with water if necessary. 
The coating thus formed has normally a coating weight of 0.001 g/m.sup. 2 
or more, preferably from 0.05 to 2 g/m.sup.2. 
The above coating operation may be conducted every 1 to ten-odd batches of 
polymerization. The formed coating has fairly good durability and retains 
the polymer scale-preventing action; therefore the coating operation is 
not necessarily performed for every batch of polymerization. Hence, the 
productivity of the manufactured polymer is improved. 
Polymerization 
After forming the coating on the inner wall surfaces of a polymerization 
vessel and other parts with which monomer may come into contact by 
application of the coating liquid, polymerization is carried out in 
accordance with conventional procedures therein. That is, a monomer having 
an ethylenically unsaturated double bond and a polymerization initiator 
(catalyst) are charged, and then, a polymerization medium such as water, 
etc. and, optionally, a dispersing agent such as suspension agents, solid 
dispersing agents, and nonionic and anionic emulsifying agents, etc. are 
charged, followed by carrying out polymerization according to conventional 
methods. 
The monomer having an ethylenically unsaturated double bond to which the 
method of this invention can be applied includes, for example, vinyl 
halides such as vinyl chloride; vinyl esters such as vinyl acetate and 
vinyl propionate; acrylic acid, methacrylic acid, and esters and salts 
thereof; maleic acid, fumaric acid, and esters and anhydrides thereof; and 
diene monomers such as butadiene, chloroprene and isoprene; aromatic vinyl 
compounds such as styrene; as well as acrylonitrile, halogenated 
vinylidenes, and vinyl ethers. 
There are no particular limitations on the type of polymerization to which 
the method of this invention can be applied. The present invention is 
effective in any types of polymerization such as suspension 
polymerization, emulsion polymerization, solution polymerization, bulk 
polymerization, and gas phase polymerization. Particularly, the present 
method is suitable to polymerizations in an aqueous medium such as 
suspension or emulsion polymerization. 
Specifically, in the case of suspension polymerization and emulsion 
polymerization, polymerization is generally performed as follows, for 
instance. 
First, water and a dispersing agent are charged into a polymerization 
vessel, and thereafter a polymerization initiator is charged. 
Subsequently, the inside of the polymerization vessel is evacuated to a 
pressure of from about 0.1 to about 760 mmHg, and a monomer is then 
charged (whereupon the pressure inside the polymerization vessel usually 
becomes from 0.5 to 30 kgf/cm.sup.2.G). Then, the polymerization is 
normally carried out at a temperature of from 30.degree. to 150.degree. C. 
During the polymerization, one or more of water, a dispersing agent and a 
polymerization initiator may be optionally added, if necessary. Reaction 
temperature during the polymerization is different depending on the kind 
of monomer to be polymerized. For example, in the case of polymerizing 
vinyl chloride, polymerization may be carried out at 30.degree. to 
80.degree. C.; in the case of polymerizing styrene, polymerization may be 
carried out at 50.degree. to 150.degree. C. The polymerization may be 
judged to be completed when the pressure inside the polymerization vessel 
falls to from about 0 to 7 kgf/cm.sup.2.G or when cooling water which 
passes through a jacket provided around the polymerization vessel 
indicates almost the same temperature at the inlet where it is charged and 
at the outlet where it is discharged (i.e., when liberation of heat due to 
polymerization reaction has been completed). The water, dispersing agent 
and polymerization initiator charged for the polymerization are used in 
amounts of about 20 to 500 parts by weight, about 0.01 to 30 parts by 
weight, and about 0.01 to 5 parts by weight, respectively, per 100 parts 
by weight of the monomer. 
In the case of solution polymerization, an organic solution such as 
toluene, xylene, pyridine and the like is used as a polymerization medium 
in place of water. A dispersing agent is optionally used. The other 
conditions are generally the same as those described for suspension and 
emulsion polymerizations. 
In the case of bulk polymerization, after the inside of a polymerization 
vessel is evacuated to a pressure of from about 0.01 mmHg to about 760 
mmHg, a monomer and a polymerization initiator are charged, and then 
polymerization is carried out at a temperature of from -10.degree. C to 
250.degree. C. For example, in the case of polymerizing vinyl chloride, 
polymerization is carried out at a temperature of from 30.degree. C. to 
80.degree. C.; and in the case of polymerizing styrene, polymerization may 
be carried out at 50.degree. C. to 150.degree. C. 
The present invention is effective in preventing polymer scale from 
depositing, independent of materials constituting the inner wall, etc. of 
a polymerization vessel. For example, this invention is effective in 
preventing polymer scale from depositing in polymerization vessels made of 
a stainless steel or other steels or vessels lined with glass. 
Any additive materials that have been added in a polymerization system can 
be used without any limitation. More specifically, the method of this 
invention can effectively prevent polymer scale from depositing, even in 
polymerization systems containing the following additives: for example, 
polymerization initiators such as t-butyl peroxyneodecanoate, 
bis(2-ethylhexyl) peroxydicarbonate, 3,5,5-trimethylhexanoyl peroxide, 
.alpha.-cumyl peroxyneodecanoate, cumene hydroperoxide, cyclohexanone 
peroxide, t-butyl peroxypivalate, bis(2-ethylhexyl) peroxydicarbonate, 
benzoyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide, 
diisopropyl peroxydicarbonate, .alpha.,.alpha.'-azobisisobutyronitrile, 
.alpha.,.alpha.'-azobis-2,4-dimethylvaleronitrile, potassium 
peroxodisulfate, ammonium peroxodisulfate, p-methane hydroperoxide; 
suspension agents comprised of natural or synthetic polymeric compounds 
such as partially saponified polyvinyl alcohols, polyacrylic acids, vinyl 
acetate/maleic anhydride copolymer, cellulose derivatives such as 
hydroxypropylmethyl cellulose, and gelatin; solid dispersing agents such 
as calcium phosphate and hydroxyapatite; nonionic emulsifying agents such 
as sorbitan monolaurate, sorbitan trioleate and polyoxyethylene alkyl 
ether; anionic emulsifying agents such as sodium lauryl sulfate, sodium 
alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate and sodium 
dioctylsulfosuccinate; fillers such as calcium carbonate and titanium 
oxide; stabilizers such as tribasic lead sulfate, calcium stearate, 
dibutyltin dilaurate and dioctyltin mercaptide; lubricants such as rice 
wax, stearic acid and cetyl alcohol; plasticizers such as DOP and DBP; 
chain transfer agents such as trichloroethylene and mercaptans as 
exemplified by t-dodecyl mercaptans; and pH adjusters. 
Addition to polymerization mass 
The polymer scale preventive agent of the present invention may be added 
into a polymerization medium preferably in the form of a solution like the 
coating liquid mentioned above in addition to the formation of the 
coating, so that the scale preventing effect is further improved. The 
amount of the polymer scale preventive agent to be added into the 
polymerization medium, preferably ranges from about 5 ppm to 1,000 ppm 
based on the whole weight of the monomer charged. The addition should be 
conducted so that it may not affect the quality of polymeric product to be 
obtained with respect to fish eyes, bulk density, particle size 
distribution, etc.

EXAMPLES 
The present invention is now described in detail by way of working examples 
and comparative examples. In each of the tables below, Experiments of Nos. 
marked with * are comparative examples, and the other Experiments working 
examples of the present invention. 
Chitosans used as the component (A) in Examples 1 and 2 below are those 
described in Table 1. 
TABLE 1 
______________________________________ 
Deacetylization 
Chitosan.sup.(3) 
Viscosity.sup.(1) 
degree.sup.(2) 
Manufacturer 
______________________________________ 
Chitosan (CLH) 
100 cP or 80.0% or more 
Yaizu 
more Suisankagaku 
Kogyo K.K. 
Chitosan (PSH) 
100 cP or 80% or more Yaizu 
less Suisankagaku 
Kogyo K.K. 
Chitosan (PSL) 
100 cP or 80% or more Yaizu 
less Suisankagaku 
Kogyo K.K. 
Chitosan (90 M) 
100 to 85.0% to WakoJunyaku 
300 cP 94.9% Kogyo K.K. 
Chitosan (100 L) 
30 to 99.0% or more 
WakoJunyaku 
100 cp Kogyo K.K. 
Chitosan (70 H) 
300 to 65.0% to WakoJunyaku 
500 cp 79.4% Kogyo K.K. 
Chitosan (80 H) 
300 to 75.0% to WakoJunyaku 
500 cp 84.9% Kogyo K.K. 
______________________________________ 
Remarks: 
.sup.(1) Viscosity: Measured at 20.degree. C. with a Btype viscometer for 
a 0.5 wt. % chitosan solution which was prepared by dissolving a chitosan 
in an aqueous 0.5 wt. % acetic acid solution. 
.sup.(2) Deacetylization degree: Measured by the PVSK colloid solution 
titration method. 
.sup.(3) Tradenames are indicated in parentheses. 
Example 1 
Polymerization was carried out in the following manner using a 
polymerization vessel with an inner capacity of 1,000 liters and having a 
stirrer. 
In each experiment, first, a component (A) and a component (B) were 
dissolved in a solvent so that the total concentration thereof might 
become the value given in Table 2, to prepare a coating liquid. The 
coating liquid was applied to the inner wall and other parts with which a 
monomer comes into contact including the stirring shaft, stirring blades 
and baffles, followed by drying under heating at 60.degree. C. for 15 min. 
to form a coating, which was then washed with water. 
Experiment of No. 101 to 103 are comparative examples in which no coating 
liquid was applied or a coating liquid containing either a component (A) 
or a component (B) was applied. 
In preparation of coating liquids containing a water-soluble basic 
polysaccharide, the water-soluble polysaccharide was completely dissolved 
in an aqueous glycollic acid solution with a pH of 4 to form a 
polysaccharide solution, which was then used for preparation of the 
coating liquids. 
The water-soluble basic polysaccharide (A), the kind of the phenazine (B), 
the total concentration of the components (A) and (B), the weight ratio of 
(A)/(B), and the solvent used in each experiment are given in Table 2. 
Subsequently, in the polymerization vessel in which a coating had been 
formed by the coating operation as above, were charged 400 kg of water, 
200 kg of vinyl chloride, 250 g of a partially saponified polyvinyl 
alcohol, 25 g of hydroxypropylmethyl cellulose and 75 g of 
bis(2-ethylhexyl) peroxydicarbonate. Then, polymerization was carried out 
at 57.degree. C. with stirring for 6 hours. After the completion of the 
polymerization, the amount of polymer scale depositing on the inner wall 
of the polymerization vessel and the whiteness or initial coloration of 
the polymer obtained were measured according to the following methods. 
Measurement of the amount of polymer scale deposition 
The scale depositing on the inner wall surface in an area of 10 cm square 
was scraped off with a stainless steel spatula as completely as possible 
to be confirmed with naked eyes, and then the scraped scale was weighted 
on a balance. Thereafter, the amount of the deposited scale per area of 1 
m.sup.2 was obtained by multiplying the measured value by 100. 
Measurement of initial coloration of polymer 
A hundred parts by weight of a polymer, one part by weight of a tin laurate 
stabilizing agent (trade name: TS-101, product of Akishima Chemical Co.) 
and 0.5 part by weight of a cadmium stabilizing agent (trade name: C-100J, 
product of Katsuta Kako Co.), and 50 parts by weight of a plasticizer DOP 
were kneaded at 160.degree. C. for 5 min. with a twin roll mill, and then 
formed into a sheet 1 mm thick. Subsequently, this sheet was placed in a 
mold measuring 4 cm .times.4 cm.times.1.5 cm (thickness), and molded under 
heating at 160.degree. C. and under a pressure of 65 to 70 kgf/cm.sup.2 to 
prepare a test specimen. This test specimen was measured for luminosity 
index L in the Hunter's color difference equation described in JIS Z 8730 
(1980). Initial coloration is evaluated to be lower with increase in L 
value. 
The L value was determined as follows. The stimulus value Y of XYZ color 
system was determined according to the photoelectric tristimulus 
colorimetry using the standard light C, a photoelectric colorimeter (Color 
measuring color difference meter Model Z-1001DP, product of Nippon 
Denshoku Kogyo K.K.) in accordance with JIS Z 8722. As the geometric 
condition for illumination and being illuminated, the condition d defined 
in section 4.3.1 of JIS Z 8722 was adopted. Next, L was calculated based 
on the equation: L=10Y.sup.1/2 described in JIS Z 8730(1980). 
The results are given in Table 2. 
TABLE 2 
__________________________________________________________________________ 
Coating liquid Amount 
Exp. 
(A) Water-soluble Total conc. of 
Wt.ratio 
Solvent of Scale 
No. polysaccharide 
(B) Phenothiazine 
(A) + (B) (wt. %) 
(A)/(B) 
(wt. ratio) (g/m.sup.2) 
L 
__________________________________________________________________________ 
101* 
-- -- -- -- -- 1300 73 
102* 
Chitosan(PSH) 
-- 0.2 100/0 
Water/Methanol (100/0) 
18 73 
103 -- Phenothiazine 
0.2 0/100 
Water/Methanol (0/100) 
11 72 
104 Chitosan(PSH) 
Phenothiazine 
0.2 100/20 
Water/Methanol (100/20) 
0 73 
105 Chitosan(PSH) 
Phenothiazine 
0.1 100/50 
Water/Methanol (100/50) 
0 73 
106 Chitosan(PSH) 
Phenothiazine 
0.1 100/100 
Water/Methanol (100/100) 
0 72.5 
107 Chitosan(PSH) 
Phenothiazine 
0.1 100/300 
Water/Methanol (100/300) 
2 72 
108 Chitosan(100 L) 
2-Acetyl- 
0.05 100/25 
Water/Methanol (100/25) 
0 72 
phenothiazine 
109 Chitosan(70 H) 
2-methylsulfinyl 
0.05 100/25 
Water/Methanol (100/25) 
0 72 
phenothiazine 
110 Clycol chitosan 
2-Nitro- 0.05 100/25 
Water/Methanol (100/25) 
0 72 
phenothiazine 
__________________________________________________________________________ 
*Comparative examples 
Example 2 
In each experiment, the coating procedure of Example 1 was repeated for a 
stainless steel polymerization vessel having an inner capacity of 20 
liters and equipped with a stirrer, except that a coating liquid in which 
the water-soluble basic polysaccharide (A), the phenazine (B), the total 
concentration of the components (A)+(B), the weight ratio of (A)/(B), and 
the solvent were as given in Table 3, was used. Experiment of No. 201 to 
203 are comparative experiments in which no coating liquid was applied or 
a coating liquid containing either a component (A) or a component (B) was 
applied. 
In preparation of coating liquids containing a water-soluble basic 
polysaccharide, the water-soluble polysaccharide was dissolved in an 
aqueous ascorbic acid solution with a pH of 4 to form a polysaccharide 
solution, which was then used for preparation of the coating liquids. 
In the polymerization vessel in which the coating was thus formed, were 
charged 9 kg of water, 225 g of sodium dodecylbenzenesulfonate, 12 g of 
t-dodecyl mercaptan, and 13 g of potassium peroxodisulfate. After the 
inner atmosphere was replaced with a nitrogen gas, 1.3 kg of styrene and 
3.8 kg of butadiene were charged, followed by polymerization at 50.degree. 
C. for 20 hours. 
After completion of the polymerization, the amount of polymer scale 
depositing on the inner wall surface was measured. 
The results are given in Table 3. 
TABLE 3 
__________________________________________________________________________ 
Coating liquid 
Exp. 
(A) Water-soluble basic 
Total conc. of 
Wt.ratio 
Solvent Amount of scale 
No. polysaccharide 
(B) Phenothiazine 
(A) + (B) (wt. %) 
(A)/(B) 
(wt.ratio) (g/m.sup.2) 
__________________________________________________________________________ 
201* 
-- -- -- -- -- 400 
202* 
Chitosan(PSH) 
-- 0.1 100/0 Water/Methanol 
15 0/0) 
203* 
-- Phenothiazine 
0.1 0/100 
Water/Methanol 
15 100) 
204 Chitosan(PSH) 
Phenothiazine 
0.1 100/100 
Water/Methanol 
3100/100) 
205 Glycol chitosan 
3,7-diamino- 
0.05 100/50 
Water/Methanol 
200/50) 
phenothiazine 
206 Methyl glycol chitosan 
3,7-diamino- 
0.05 100/50 
Water/Methanol 
2100/50) 
phenothiazine 
__________________________________________________________________________ 
*Comparative examples