Process to prevent polymer scale adhesion using an aromatic compound and a salt of polyvinylsulfuric acid

A process to prevent scale adhesion on rector surfaces when polymerizing vinyl esters, vinyl esthers, carboxylic acids, styrene or diene monomers. Coating of internal reactor surfaces with a combination of an amino containing aromatic compound, and an alkali metal or ammonium salt of polyvinylsulfuric acid results in the scale prevention. This combination is applied to reactor surfaces via its mixture with a solvent and is subsequently dried to form the coating.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a polymer scale preventive agent and a 
method of preventing polymer scale deposition using it for polymerization 
of a particular polymerizable monomer having an ethylenic double bond. 
2. Description of Prior Art 
In processes of preparing polymers by polymerizing a monomer in a 
polymerization vessel, the problem that polymers deposit on the inner wall 
surface and other parts which come into contact with the monomer such as 
stirring blades of the polymerization vessel 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 the cooling capacity of 
the polymerization vessel are lowered; that the polymer scale may peel and 
mix into manufactured polymer, thereby impairing the quality of the 
manufactured polymer; and that removal of such polymer scale is laborious 
and hence time-consuming. Further, since the polymer scale contains 
unreacted monomer, there is a danger that the operators may be exposed to 
the unreacted monomer, which may cause some physical disorders. 
Heretofore, there are known methods for preventing polymer scale deposition 
in which the inner wall and so forth are coated with a suitable substance 
as a polymer scale preventive agent. Such substances suited as polymer 
preventive agents include, for example, particular polar compounds 
(Japanese Patent Publication (KOKOKU) No. 45-30343(1970)); dyes or 
pigments (Japanese Patent Publication (KOKOKU) Nos. 45-30835(1970) and 
52-24953(1977); aromatic amine compound (Japanese Pre-examination Patent 
Publication (KOKAI) No. 51-50887(1976)); a reaction product of a phenolic 
compound with an aromatic aldehyde (Japanese Pre-examination Patent 
Publication (KOKAI) No. 55-54317(1980)). 
These methods are effective in preventing polymer scale deposition, in the 
case where the monomer to be polymerized is a vinyl halide such as vinyl 
chloride or a monomer mixture containing largely a vinyl halide. However, 
in the case where the monomer having an ethylenic double bond to be 
polymerized is a monomer having the general formula: 
EQU CH.sub.2 .dbd.CXY 
wherein X is a hydrogen atom or the methyl group; Y is a hydrogen atom, an 
alkyl group or a group represented by the formula: --COOH, --COOM (where M 
is an alkali metal or an ammonium ion), --COOR, --OCOR, --OR (where in the 
formulas R is an alkyl group), --CN, --C.sub.6 H.sub.5, --C.sub.6 H.sub.4 
Z (where Z is an hydrogen atom, --OH, --CH.sub.3 or --CH.dbd.CH.sub.2), or 
--CH.dbd.CH.sub.2 including styrene, .alpha.-methylstyrene, acrylates and 
acrylonitrile, which have a high dissolving power against the coatings 
formed by the above prior art methods, the coatings may be partly or 
completely dissolved away. Consequently, it becomes impossible to prevent 
the deposition of polymer scale effectively. Particularly, among the 
monomers, styrene, .alpha.-methylstyrene, acrylates and acrylonitrile have 
extremely strong dissolving power; therefore effects of preventing polymer 
scale can not be attained as desired. Besides, particularly where a 
polymerization vessel made of stainless steel is used, polymer scale is 
liable to deposit on the inner wall surfaces of the polymerization vessel 
as compared with the case where polymerization vessels whose inner walls 
are lined with glass. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a polymer 
scale preventive agent and a method capable of effectively preventing 
polymer scale deposition on the inner wall of a polymerization vessel in 
the polymerization or copolymerization of the monomer of the general 
formula (I) having a strong dissolving power. 
According to the present invention, as a means of achieving the object 
above, there is provided a polymer scale preventive agent for use in a 
polymerization vessel in polymerization of a polymerizable monomer having 
the general formula (I): 
EQU CH.sub.2 .dbd.CXY (I) 
wherein X is a hydrogen atom or the methyl group; Y is a hydrogen atom, an 
alkyl group (normally, an alkyl group having 1 to 4 carbon atoms such as 
methyl, ethyl, propyl and butyl) or a group represented by the formula: 
--COOH, --COOM (where M is an alkali metal such as K, Na or Li or an 
ammonium ion), --COOR, --OCOR, --OR (where in the formulas R is an alkyl 
group, normally, an alkyl group having 1 to 4 carbon atoms), --CN, 
--C.sub.6 H.sub.5, --C.sub.6 H.sub.4 Z (where Z is an hydrogen atom, --OH, 
--CH.sub.3 or --CH.dbd.CH.sub.2), or --CH.dbd.CH.sub.2, said agent 
comprising: 
(A) an aromatic compound having at least one group selected from the class 
consisting of primary, secondary and tertiary amino groups and the 
quaternary ammonium group and/or a dye having at least one group selected 
from said class, and 
(B) at least one compound selected from the group consisting of alkali 
metal salts and ammonium salts of a polyvinylsulfuric acid. 
According to the present invention, there is also provided a method of 
preventing polymer scale deposition in a polymerization vessel in 
polymerization of a polymeriable monomer having the general formula (I), 
wherein said polymerization is carried out in a polymerization vessel 
having a coating, on its inner wall surfaces, comprising: 
(A) an aromatic compound having at least one group selected from the class 
consisting of primary, secondary and tertiary amino groups and the 
quaternary ammonium group and/or a dye having at least one group selected 
from said class, and 
(B) at least one compound selected from the group consisting of alkali 
metal salts and ammonium salts of a polyvinylsulfuric acid. 
The present invention also provides a polymerization vessel having the 
coating formed as set out above on the inner wall. 
According to the present invention, polymer scale deposition can be 
effectively prevented even in the polymerization copolymerization or of 
monomers having said general formula (I) in which effective prevention of 
polymer scale deposition has been so far difficult due to the high 
dissolving power of the monomer against the conventional scale preventive 
coatings. Particularly, even in polymerizing monomers such as styrene, 
.alpha.-styrene, acrylic acid, acrylates, vinyl acetate and acrylonitrile, 
polymer scale deposition can be prevented. 
This prevention is effective independent of materials of the inner wall; in 
the polymerization in a stainless steel polymerization vessel, polymer 
deposition can be effectively prevented. 
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
(A) Aromatic Compound and/or Dye. 
Component (A) of the polymer scale preventive agent is an aromatic compound 
having at least one group selected from the class consisting of primary, 
secondary and tertiary amino groups and the quaternary ammonium group 
and/or a dye having at least one group selected from said class. 
The aromatic compound having said group includes, for example, aromatic 
amines such as diaminodiphenylamine, ethylenedianiline, diaminonaphthalene 
and like, acridines such as acridine, diaminoacridine and the like, 
phenazines such as phenazine, aminophenazines and the like, azobenzenes 
such as aminoazobenzenes, hydroxyazobenzenes and the like, hydrochlorides 
and sulfates thereof, and alkaloids such as berberine hydrochloride. 
The dye having said group includes, for example, C.I. Solvent Yellow 2, 4, 
5, 6, 14, 15, 16, 19, 21, 33, 56, 61 and 80; C.I. Solvent Orange 1, 2, 14, 
37, 40, 44 and 45; C.I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 
82, 83, 84, 100 and 121;C.I. Solvent Brown 3, 5, 20 and 37; C.I. Solvent 
Black 3, 5, 7, 22 and 23; C.I. Acid Black 123; C.I. Disperse Yellow 1, 3, 
4, 5, 7, 31, 33, 49, 50, 60, 61, 64, 66, 71, 72, 76, 78 and 79; C.I. 
Disperse Orange 1, 3, 5, 11, 13, 20, 21, 30, 32, 41, 43, 45, 46, 49, 50 
and 51; C.I. Disperse Red 1, 4, 5, 7, 11, 12, 13, 15, 17, 43, 52, 53, 54, 
55, 56, 58, 59, 60, 65, 72, 73, 74, 75, 76, 80, 82, 84, 88, 90, 91, 92, 
97, 99, 101, 103, 113, 116, 117, 122, 125, 126, 127, 128 and 129; C.I. 
Disperse Violet 1, 4, 8, 10, 18, 23, 24, 26, 28, 30, 33, 37 and 38; C.I. 
Disperse Blue 1, 5, 6, 43, 44, 88 and 96; C.I. Disperse Brown 3 and 5; 
C.I. Disperse Black 1, 2, 10, 26, 27, 28, 29, 30 and 31; C.I. Basic Red 2 
and 12; C.I. Basic Blue 1, 6, 7, 9, 12, 16, 24 and 25; C.I. Basic Black 2; 
C.I. Basic Orange 2, 14 and 15; C.I. Basic Violet 10 and 14; C.I. Basic 
Yellow 1, 4 and 6; C.I. Basic Green 5 and 12; C.I. Basic Brown 1; and 
condensation products of an aromatic amine compound with an aromatic nitro 
compound, e.g., condensation products obtained by condensation of an 
aromatic amine compound and an aromatic nitro compound in the presence of 
a mineral acid and a specified condensation catalyst at a temperature of 
from 100.degree. C. to 250.degree. C., disclosed in U.S. Pat. No. 
4,528,336 which is incorporated herein by reference, specifically 
condensation products obtained by condensation of an aromatic amine 
compound having the general formula (II): 
##STR1## 
wherein R.sup.1 is a hydrogen atom, chlorine atom, amino group, phenylazo 
group --N.dbd.N--C.sub.6 H.sub.5, hydroxy group, acetyl group, methoxy 
group, phenylamino group, aminophenylamino group, methoxyphenylamino 
group, dimethylamino group, hydroxyphenylamino group, acetylamino group or 
an alkyl group having from 1 to 3 carbon atoms, and R.sup.2 is a hydrogen 
atom, amino group, hydroxy group or methyl group, with an aromatic nitro 
compound having the general formula 
##STR2## 
wherein R.sup.3 is a hydrogen atom, chlorine atom, hydroxy group, methoxy 
group, ethoxy group, amino group, carboxyl group --COOH or sulfo group 
--SO.sub.2 OH, in the presence of a condensation catalyst at a temperature 
of 100.degree. C. to 250.degree. C. disclosed in said U.S. Patent..sup.(1) 
The aromatic compounds and dyes can be used singly or in combination of two 
or more. 
Among them, out of the aromatic compounds, preferred are 
diaminodiphenylamine, diaminonaphthalenes, diaminoacridines, 
aminoazobenzenes and berberine hydrochloride, and out of the dyes, 
preferred are C.I.Solvent Black 3, 5, 7 and 22, C.I.Basic Black 2, 
C.I.Basic Orange 14, and the condensation products obtained by 
condensation of an aromatic amine compound having the general formula (II) 
wherein R.sup.1 is a hydrogen atom, chlorine atom, amino group, 
phenylamino group or hydroxyphenylamino group and R.sup.2 is a hydrogen 
atom, amino group, hydroxy group or methyl group, with an aromatic nitro 
compound having the general formula (III) wherein R.sup.3 is a hydrogen 
atom, chlorine atom, hydroxy group, methoxy group, ethoxy group, amino 
group or carboxyl group, disclosed in the U.S. Pat. No. 4,528,336. 
Particularly preferred are C.I.Solvent Black 3, 5, 7 and 22 and 
Condensation Products I to XXI disclosed in the U.S. Patent and described 
in Table 4 later..sup.(2) 
(b) Salt of Polyvinylsulfuric Acid 
The salt of polyvinylsulfuric acid used as component (B) of the polymer 
scale preventive agent preferably has a polymerization degree of 500 or 
more, more preferably from 1,000 to 5,000 because the polymer scale 
preventing effects are enhanced. 
The alkali metal salt or ammonium salt of polyvinylsulfuric acid is, for 
example, represented by the following structural formula: 
##STR3## 
wherein M is an alkali metal such as K, Na or the like or an ammonium ion 
and n is an integer, and the sulfonation degree is preferably from 90 to 
95%. 
The polymer scale preventive agent is used for preventing deposition of 
polymer scale by forming a coating on the inner wall surfaces, etc. of a 
polymerization vessel. 
The polymer scale preventive agent may contain, in addition to components 
(A) and (B), a solvent, a surface active agent, a water-soluble polymer 
compound, an organic or inorganic pH adjuster, etc. For forming said 
coating on the inner wall surfaces, etc. of a polymerization vessel, 
normally the polymer scale preventive agent is used in the form of a 
liquid (solution or dispersion), i.e., as a coating liquid. 
In the polymer scale preventive agent, the weight ratio of component 
(A)/component (B) is normally in the range of 0.1/100 to 100/1, preferably 
1/100 to 100/10. If the amount of component (B) relative to that of 
component (A) is outside the range above, improvement in prevention of 
polymer scale due to the combined use of components (A) and (B) is hardly 
obtained. If the ratio of component (A)/component (B) is unsuitable, the 
coating liquid may be unstable and sediment of component (A) may be 
formed, so that uniform coatings can be formed with difficulty. 
Preparation of Coating Liquid 
The coating liquid mentioned above is prepared by adding component (A) and 
component (B) to a suitable solvent. Specifically, for example, to a 
solution of component (A) in a suitable solvent, component (B) in a solid 
state or its aqueous solution is added. 
The solvent used for preparation of the coating liquid include, for 
example, water; alcohols such as methanol, ethanol, propanol, 1-butanol, 
2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 3-methyl-1butanol, 
2-methyl-2-butanol, and 2-pentanol; ketones such as acetone, methyl ethyl 
ketone, and methyl isobutyl ketone; ethers such as 4-methyl dioxolan, and 
ethylene glycol diethyl ether; esters such as methyl formate, ethyl 
formate, methyl acetate, and methyl acetoacetate; furans such as 
tetrahydrofuran, furfural, fulfuryl alcohol and tetrahydrofurfuryl 
alcohol; aliphatic hydrocarbons such as n-hexane and n-heptane; aromatic 
hydrocarbons such as benzene, toluene, and xylene; halogenated 
hydrocarbons such as chloromethylene, 1-chlorobutane, amyl chloride, 
dichloroethylene, and 1,1,2-trichloroethane, and aprotic organic solvents 
such as acetonitrile, formamide, dimethylformamide, dimethyl sulfoxide and 
N-methylpyrrolidone. These solvents are used singly or as a mixed solvent 
of two or more. 
Among these solvents, particularly preferred are water and alcohols such as 
methanol and ethanol, and mixed solvents thereof. 
The total concentration of component (A) and component (B) is not limited 
as long as the coating weight after dried described later is attained, but 
normally from 0.0001 to 5% by weight, preferably from 0.001 to 2% by 
weight. 
The coating liquid preferably contains (C) a water-soluble polymer 
compound, and more preferably further contains (D) a pH adjuster in such 
an amount that pH of the liquid may be adjusted to 7 or below, preferably 
6 or below, because the polymer scale preventing effects are further 
improved. 
Water-Soluble Polymer Compound 
The water-soluble polymeric compound (C) includes, for example, hydroxyl 
group-containing polymeric compounds, amphoteric polymeric compounds, 
anionic polymeric compounds, and cationic polymeric compounds. 
The hydroxyl group-containing polymeric compound includes, for example, 
starches and derivatives thereof such as amylose, amylopectin, dextrin, 
oxidized starch, acetyl starch, nitrostarch, methyl starch, and 
carboxymethyl starch; hydroxyl group-containing plant mucous 
polysaccharides such as pectic acid, protopectin, pectinic acid, 
laminarin, fucoidin, agar, and carrageenan; hydroxyl group-containing 
animal mucous polysaccharides such as hyaluronic acid, chondroitin 
sulfuric acid, heparin, keratosulfuric acid, chitin, charonin, and 
limacoitin sulfuric acid; nucleic acids such as ribonucleic acid and 
deoxyribonucleic acid; cellulose derivatives such as methyl cellulose, 
ethyl cellulose, carboxymethyl cellulose, glycol cellulose, benzyl 
cellulose, cyanoethyl cellulose, cellulose methylene ether, 
triphenylmethyl cellulose, formyl cellulose, cellulose acetate, cellulose 
propionate, cellulose butyrate, cellulose acetate propionate, cellulose 
sulfonate ester, cellulose carbamate ester, nitrocellulose, cellulose 
phosphate, and cellulose xanthogenate; hemicelluloses such as xylan, 
mannan, arabogalactan, and araban; lignins such as alcohol lignin, dioxane 
lignin, phenol lignin, hydrotropic lignin, mercaptolignine, thioglycollic 
acid lignin, lignin sulfonic acid, alkali lignin, thioalkali lignin, acid 
lignin, cuproxam lignin, and periodate lignin; phenol-formaldehyde resins, 
partially saponified polyvinyl alcohols, and polyvinyl alcohols. 
The amphoteric polymeric compounds include, for example, glue, gelatin, 
casein, and albumin. 
The anionic polymeric compound includes, for example, anionic polymeric 
compounds having a carboxyl group or sulfonic acid group in the side chain 
as exemplified by sulfomethylated compounds of polyacrylamide, polyacrylic 
acid, alginic acid, an acrylamide/vinylsulfonic acid copolymer, 
polymethacrylic acid and polystyrenesulfonic acid, and alkali metal salts 
or ammonium salts of these, and carboxymethyl cellulose. 
The cationic polymeric compound includes cationic polymeric electrolytes 
containing a nitrogen atom, including, for example, polyvinylamines, 
polyethyleneamines, polyethyleneimines, polyacrylamides, 
N-vinyl-2-pyrrolidone/acrylamide copolymer, polyvinylpyridines, 
polyvinylpyrrolidones, polyvinylcarbazoles, polyvinylimidazolines, 
polydimethylaminoethyl acrylates and polydimethylaminoethyl methacrylates. 
These water-soluble polymeric compounds may be used singly or in 
combination of two or more. 
Among these water-soluble polymer compounds (C), preferred are 
carboxymethyl cellulose, methyl cellulose, polyacrylic acids, 
polymethacrylic acids and polyvinyl alcohols. 
The concentration of component (C) in a coating liquid is preferably in the 
range of from 0.01 to 5 g/liter, more preferably from 0.01 to 2 g/liter. 
(D) pH adjuster 
The pH adjuster (D) includes, for example, sulfuric acid, hydrochloric 
acid, phosphoric acid, nitric acid, carbonic acid, perchloric acid, 
molybdic acid, tungstic acid, phosphomolybdic acid, phosphotungstic acid, 
molybdosilicic acid, tungstosilicic acid, formic acid, acetic acid, oxalic 
acid, lactic acid, maleic acid, glycollic acid, thioglycollic acid, 
p-toluenesulfonic acid, tannic acid, phytic acid and the acidic salts 
thereof. These may be used singly or in combination of two or more. Among 
these, particularly preferred are phosphoric acid, hydrochloric acid, 
perchloric acid, molybdic acid, tungstic acid, phosphomolybdic acid, 
phosphotungstic acid, molybdosilicic acid, tungstosilicic acid, 
p-toluenesulfonic acid, phytic acid and the acidic salts thereof. These pH 
adjusters are preferably used as an aqueous solution with a suitable 
concentration when the pH of a coating liquid is adjusted. 
Formation of the coating 
The polymer scale preventive liquid is applied to the inner walls of a 
polymerization vessel and then dried sufficiently, followed by washing 
with water if necessary, to form the coating. The drying may be carried 
out at a temperature from room temperature to 100.degree. C., for 
instance. 
The polymer scale preventive liquid is preferably applied to not only the 
inner wall surface of a polymerization vessel but also other parts with 
which the monomer comes into contact during polymerization to form a 
coating on such parts. For example, it is preferred to apply the coating 
solution to a stirring shaft, stirring blades, condensers, headers, search 
coil, bolts, nuts, etc. to form the coating thereon. 
More preferably, for formation of the coating, the polymer scale preventive 
liquid is applied to portions with which monomers does not come into 
contact during polymerization but on which polymer scale may deposit, for 
example, portions of recovery system for unreacted monomer with which 
unreacted monomer comes into contact, such as inner surfaces, etc. of 
equipment and pipes of the recovery system. Specifically, such portions 
include the inner surfaces of monomer distillation columns, condensers, 
monomer stock tanks and valves. 
The method of applying the coating solution is not particularly limited, 
and includes, for example, the brush coating, spray coating, the method of 
filing the polymerization vessel with the coating solution 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 surfaces provided by application of the 
polymer scale preventive liquid, is not limited, either. Following methods 
can be used. That is, a method in which, after the solution is applied, 
hot air with an 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 
to from 30 to 80.degree. C., and the polymer scale preventive liquid is 
directly applied to the heated inner wall surfaces, etc. After dried, the 
coated surfaces are washed with water if necessary. 
The coating thus obtained normally has a coating weight of preferably 0.001 
to 5 g/m.sup.2, and more preferably from 0.001 to 3 g/m.sup.2. 
Polymerization 
After the formation of the coating on the inner wall surfaces of a 
polymerization vessel, and preferably other parts with which monomer may 
come into contact during polymerization by coating treatment, 
polymerization is carried out in accordance with conventional procedures. 
That is, a monomer represented by the general formula (I), a 
polymerization initiator, and optionally a polymerization medium such as 
water, etc., and a dispersing agent are charged into the polymerization 
vessel, followed by carrying out polymerization according to conventional 
methods. 
The monomer to be polymerized according to the present method includes, for 
example, vinyl esters such as vinyl acetate and vinyl propionate; acrylic 
acid, methacrylic acid, and esters or salts thereof; diene monomers such 
as butadiene, chloroprene and isoprene; styrene and .alpha.-methylstyrene; 
and vinyl ethers. These monomers can be used singly or in combination of 
two or more. 
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 type of polymerization such as suspension polymerization, 
emulsion polymerization, solution polymerization, bulk polymerization, and 
gas phase polymerization. 
In the following, general conditions are described on each type of 
polymerization. 
In the case of suspension or emulsion polymerization, for example, water 
and a dispersing agent are charged into a polymerization vessel, and 
thereafter a polymerization initiator and monomers are charged (whereupon 
the pressure inside the polymerization vessel usually becomes from 0 to 10 
kgf/cm.sup.2.G). During the polymerization, one or more of water, a 
dispersing agent and a polymerization initiator may be added, if 
necessary. The polymerization may be judged to be completed when a desired 
conversion is reached (normally, a conversion of 80-100% has been 
reached). The water, dispersing agent and polymerization initiator to be 
charged for polymerization are used in amounts of about 50 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 solvent such as toluene, 
xylene and pyridine is used as the polymerization medium in place of 
water. The 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 into the 
polymerization vessel, and then polymerization is carried out at a 
temperature of from -10.degree. C. to 250.degree. C. 
Application of the method of preventing polymer scale deposition of the 
present invention to polymerization, makes it possible to prevent polymer 
scale from depositing, independent of materials constituting the inner 
wall, etc. of a polymerization vessel. For example, this method can 
prevent deposition of polymer scale even in the case polymerization is 
carried out in a polymerization vessel made of a steel including stainless 
steel or a vessel whose inner walls are lined with glass. 
Any additive materials that have been conventionally added in a 
polymerization system can be used without any limitation. More 
specifically, the method of this invention can effectively prevent 
polymers from depositing, even in polymerization systems containing the 
following additives: for example, polymerization catalysts such as t-butyl 
peroxyneodecanoate, bis(2-ethylhexyl) peroxydicarbonate, 
3,5,5-trimethylhexanoyl peroxide, .alpha.-acumyl 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-menthane 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 mercaptans such as t-dodecyl mercaptan, and 
trichloroethylene; and pH adjusters. 
The polymerizations to which the polymer scale preventive agent can be 
suitably applied, include, for example, emulsion polymerizations and 
suspension polymerizations for production of copolymers of styrene with 
acrylic acid or its ester, copolymers of styrene with metharylic acid or 
its ester, polystyrenes, ABS copolymer resins, and synthetic rubbers such 
as SBR, NBR, CR, IR and IIR. 
In the practice of the present method, the coating operation of the coating 
liquid may be conducted every batch or every some tens of batches. The 
coating formed has a high durability and maintains the polymer scale 
preventing action. Therefore, normally, coating treatment may be conducted 
every several batches, so that the polymerization vessel can be used 
repeatedly without deposition of polymer scale on the inner wall, etc. of 
the vessel.

EXAMPLES 
The present invention is now described in detail by way of working examples 
and comparative examples. In each of the tables below, coating liquids or 
Experiment marked with * indicate comparative examples, and the other 
Experiment Nos., working examples of the present invention. 
EXAMPLE 1 
Preparation of coating liquids 
Component (A) (the aromatic compound and/or dye) was dissolved or dispersed 
in a solvent so as to give a concentration of 0.1% by weight. To the 
resulting mixture, an aqueous solution of potassium polyvinylsulfate with 
a polymerization degree of 1,500 was added to prepare Coating liquids, 
provided that in place of potassium polyvinylsulfate, sodium 
polyvinylsulfate with a polymerization degree of 1,500 was used for 
Coating Solution No. 23 and ammonium polyvinylsulfate with a 
polymerization of 1,500 was for Coating Solution No. 24. 
In Table 1, in regard to each of the coating liquids, the kind of component 
(A), the weight ratio of the component (A)/(B), the composition and the 
weight ratio of water/an organic solvent in the solvent used are given. 
However, the coating liquids of Nos. 21 and 22 are comparative examples in 
which no component (B) is contained. 
TABLE 1 
__________________________________________________________________________ 
No. of Wt. ratio 
Solvent 
coating liquid 
(A) Aromatic compound or dye 
(A)/(B) 
Composition 
Wt. ratio 
__________________________________________________________________________ 
1 p,p'-diaminodiphenylamine 
60/100 
Water/Methanol 
50/50 
2 Berberine hydrochloride 
60/100 
" 60/40 
3 1,8-diaminonaphthalene 
60/100 
" 60/40 
4 3,6-diaminoacridine 
60/100 
Water/Ethanol 
70/30 
5 p-aminoazobenzene 
60/100 
" 40/60 
6 Condensation product I.sup.(1) 
40/100 
Water/Methanol 
50/50 
7 Condensation product IV.sup.(1) 
40/100 
" 50/50 
8 Condensation product XI.sup.(1) 
40/100 
" 50/50 
9 Condensation product XII.sup.(1) 
40/100 
" 50/50 
10 Condensation product XIV.sup.(1) 
40/100 
" 50/50 
11 Condensation product XVII.sup.(1) 
40/100 
" 50/50 
12 C.I. Solvent Black 3 
50/100 
Water/Ethanol 
50/50 
13 C.I. Solvent Black 5 
50/100 
" 50/50 
14 C.I. Solvent Black 7 
50/100 
" 40/60 
15 C.I. Solvent Black 22 
50/100 
Water/Methanol 
60/40 
16 C.I. Basic Orange 2 
50/100 
Water/Methanol 
60/40 
17 C.I. Basic Black 2 
50/100 
" 60/40 
18 C.I. Disperse Yellow 7 
50/100 
" 50/50 
19 C.I. Disperse Orange 3 
50/100 
" 60/40 
20 C.I. Basic Brown 1 
50/100 
" 50/50 
21* Condensation product I.sup.(1) 
100/0 
Methanol -- 
22* Condensation product XVII.sup.(1) 
100/0 
" -- 
23 Condensation product I.sup.(1) 
40/100 
Water/Methanol 
50/50 
24 Condensation product I.sup.(1) 
40/100 
" 50/50 
__________________________________________________________________________ 
Remarks: 
(1) The condensation products are disclosed in U.S. Pat. No. 4,528,336 an 
described in Table 4 later. 
EXAMPLE 2 
In each experiment, polymerization was carried out in the following manner 
using a stainless steel polymerization vessel with an inner capacity of 20 
liters and equipped with a stirrer. 
In Experiment No. 102 to 127, a coating liquid indicated in Table 2, which 
was prepared in Example 1, was applied to the inner wall surfaces, 
stirring shaft, stirring blades, baffles and other parts with which 
monomers come into contact during polymerization, and then dried at 
50.degree. C. for 15 minutes by heating and washed with water to form a 
coating. The coating thus formed had a coating weight of 0.1 g/m.sup.2 
after dried. 
In the experiments coating solutions were applied as below. 
Experiment No. 101: No coating was formed. 
Experiment Nos. 102-119: The coating liquids were used as they were 
prepared in Example 1. 
Experiment Nos. 120-127: To the coating liquids indicated in Table 2 as 
prepared in Example 1, a component (C) (water soluble polymer compound) 
and a component (D) (pH adjuster) were added, and resulting liquids were 
used for application. 
Among the experiments above, experiments of Nos. 101-103 are comparative 
examples. 
In Table 2, No. of the coating liquid, the kind and concentration of 
component (C), the kind of component (D), and the pH of the coating liquid 
in each experiment are given. 
In the polymerization vessel in which coating was so formed, were charged 8 
kg of water, 5.2 kg of styrene, 2.8 kg of methacrylic acid, 8 g of a 
partially saponified polyacrylamide and 24 g of 
.alpha.,.alpha.'-azobisisobutylonitrile. Polymerization was then carried 
out with stirring at 90.degree. C. for 5 hours. After the completion of 
polymerization, the amount of polymer scale deposition on the inner wall 
surfaces was measured. The results are given in Table 2. 
TABLE 2 
__________________________________________________________________________ 
Amount of 
Coating liquid polymer 
Exp. (C) Water-soluble 
(C) Concentration scale 
No. 
No. 
polymer compound 
(g/l) (D) pH adjuster 
pH 
(g/m.sup.2) 
__________________________________________________________________________ 
101* 
-- -- -- -- -- 
1200 
102* 
21* 
-- -- -- 3 250 
103* 
22* 
-- -- -- 3 300 
104 
6 -- -- -- 5 12 
105 
11 -- -- -- 5 15 
106 
8 -- -- -- 5 10 
107 
10 -- -- -- 5 8 
108 
1 -- -- -- 7 25 
109 
2 -- -- -- 7 18 
110 
3 -- -- -- 7 20 
111 
4 -- -- -- 9 16 
112 
5 -- -- -- 7 26 
113 
12 -- -- -- 7 18 
114 
15 -- -- -- 5 20 
115 
16 -- -- -- 4 36 
116 
17 -- -- -- 3 27 
117 
18 -- -- -- 7 30 
118 
19 -- -- -- 7 21 
119 
20 -- -- -- 4 25 
120 
3 Carboxymethylcellulose 
0.5 Perchloric acid 
5 10 
121 
4 Polyacrylic acid 
0.2 Phosphoric acid 
5 2 
122 
6 Polymethacrylic acid 
0.1 Phytic acid 
4 2 
123 
11 Methylcellulose 
0.5 p-toluenesulfonic acid 
4 6 
124 
15 Polymethacrylic acid 
0.5 Sulfuric acid 
4 5 
125 
20 PVA 0.2 Tungstic acid 
3 2 
126 
6 " 0.1 Phosphoric acid 
2 1 
127 
10 " 0.1 Phytic acid 
2 2 
128 
23 " 0.1 Phytic acid 
3 4 
129 
24 " 0.1 Phosphoric acid 
3 2 
__________________________________________________________________________ 
Remarks: 
PVA represents polyvinyl alcohol. 
EXAMPLE 3 
In each experiment, a coating was formed inside a polymerization vessel 
having an inner capacity of 20 liters and equipped with a stirrer by 
conducting the operations of applying a coating liquid, drying and washing 
with water in the same manner as in Example 2. The coating thus formed had 
a coating weight of 0.1 g/m.sup.2 after dried. 
In the experiments, the coating liquids were used as below. 
Experiment No. 201: No coating was formed. 
Experiment Nos. 202-207: The coating liquids indicated in Table 3 were used 
as they were prepared in Example 1. 
Experiment Nos. 208-225: To the coating liquids indicated in Table 3 as 
prepared in Example 1, a component (C) (water soluble polymer compound) 
and a component (D) (pH adjuster) were added, and resulting liquids were 
used for application. 
Among the experiments above, Experiment Nos. 201-203 are comparative 
examples. 
In Table 3, No. of the coating liquid, the kind and concentration of 
component (C), the kind of component (D), and the pH of the coating liquid 
in each experiment are given. 
In the polymerization vessel in which a coating was so formed, were charged 
4 kg of styrene, 2.7 kg of acrylonitrile, 7 kg of water, 135 g of 
hydroxyapatite, 2.7 g of lauroyl peroxide, 20 g of t-dodecylmercaptan and 
27 g of lauroyl peroxide. Polymerization was then carried out with 
stirring at 70.degree. C. for 1 hour. Thereafter, the temperature was 
raised from 70.degree. C. to 80.degree. C. over 2 hours, and reaction was 
carried out at 80.degree. C. for 1 hour to produce a polymer. After the 
completion of polymerization, the resulting polymer and unreacted monomers 
were recovered, and the inside of the polymerization vessel was washed 
with water. The amount of polymer scale deposition was then measured. The 
results are given in Table 3. 
TABLE 3 
__________________________________________________________________________ 
Amount of 
Coating liquid polymer 
Exp. (C) Water-soluble 
(C) Concentration scale 
No. 
No. 
polymer compound 
(g/l) (D) pH adjuster 
pH 
(g/m.sup.2) 
__________________________________________________________________________ 
201* 
-- -- -- -- -- 
650 
202* 
21* 
-- -- -- 3 300 
203* 
22* 
-- -- -- 3 350 
204 
6 -- -- -- 5 56 
205 
11 -- -- -- 5 65 
206 
7 -- -- -- 5 49 
207 
9 -- -- -- 5 40 
208 
10 Methylcellulose 
0.5 -- 5 35 
209 
10 -- -- Phytic acid 
3 32 
210 
10 Polymethacrylic acid 
0.3 Phosphoric acid 
4 5 
211 
10 Benzylcellulose 
0.5 p-tolunesulfonic acid 
3 8 
212 
13 Amylose 0.5 Acetic acid 
2 15 
213 
13 PVA 0.1 Phosphoric acid 
2 6 
214 
13 Carboxymethylcellulose 
1.0 Maleic acid 
3 9 
215 
2 PVA 0.7 Phytic acid 
6 2 
216 
2 Polyacrylic acid 
0.2 p-tolunesulfonic acid 
6 12 
217 
3 " 0.1 Tungstic acid 
6 12 
218 
4 Gelatin 1.0 Sulfuric acid 
5 29 
219 
4 PVA 0.3 Phytic acid 
5 3 
220 
16 Methylcellulose 
0.5 Lactic acid 
3 24 
221 
17 Polyacrylic acid 
0.5 Perchloric acid 
2 10 
222 
18 Carboxymethylcellulose 
0.8 Phytic acid 
6 18 
223 
19 PVA 0.2 Molybdosilisic acid 
6 5 
224 
20 Polymethacrylic acid 
0.2 Phosphoric acid 
3 13 
225 
20 Polystyrenesulfonic acid 
1.0 " 3 20 
226 
23 Polyacrylic acid 
1.0 Phosphoric acid 
6 1 
227 
24 PVA 1.0 Phytic acid 
6 2 
__________________________________________________________________________ 
Remarks: 
PVA represents polyvinyl alcohol. 
Remarks 
(1) In U.S. Pat. No. 4,528,336, reactants and reaction conditions are as 
below. 
Examples of the aromatic amino compound include: aniline, 1,2-, 1,3-, and 
1,4-phenylenediamines, 2-, 3- and 4-aminophenols, 2-, 3- and 
4-chloroanilines, 4-aminoazobenzene, 2,4-diaminoazobenzene, 
4-aminoacetanilide, 2-, 3- and 4-methylanilines, 4-aminodiphenylamine, 
2-aminodiphenylamine, 4,4'-diaminodiphenylamine, 
N,N-dimethyl-1,4-phenylenediamine, 4-amino-3'-methoxydiphenylamine, 
4-amino-4'-hydroxydiphenylamine, 4-chloro-1,2-phenylenediamine, 
4-methoxy-1,2-phenylenediamine, 2-amino-4-chlorophenol, 2,3-diaminotoluene 
and the like, among which particularly preferred are aniline. 1,2-, 1,3- 
and 1,4-phenylenediamines, 2-, 3- and 4-aminophenols, 4-aminodiphenylamine 
and 4,4'-diaminodiphenylamine. 
Examples of the aromatic nitro compound include: nitrobenzene, 2-, 3- and 
4-nitrophenols, 2-, 3- and 4-nitroanisoles, 2-, 3- and 4-nitrophenetoles, 
2-, 3- and 4-chloronitrobenzenes, 2-, 3- and 4-nitroanilines, 2-, 3- and 
4-nitrobenzoic acids, 2-, 3- and 4-nitrobenzenesulfonic acids and the 
like, among which particularly preferred are nitrobenzene, 2-, 3- and 
4nitrophenols, 2-, 3- and 4-nitrobenzoic acids and 2-, 3- and 
4-nitrobenzenesulfonic acids. 
The condensation reaction of the above named aromatic amine and nitro 
compounds is carried out in the presence of a mineral acid and a 
condensation catalyst. 
Suitable mineral acids are hydrochloric acid, sulfuric acid, nitric acid, 
phosphoric acid and hydrobromic acid, of which the former two are 
preferred. 
The condensation catalyst is preferably an oxidizing compound selected from 
the class consisting of permanganic acid, permanganates such as potassium 
permanganate, chromic acid and related compounds such as chromium 
trioxide, potassium bichromate and sodium chlorochromate, heavy metal 
nitrates such as silver nitrate and lead nitrate, halogens such as iodine, 
bromine and chlorine, inorganic and organic peroxides such as hydrogen 
peroxide, sodium peroxide, dibenzoyl peroxide, potassium persulfate, 
ammonium persulfate, peracetic acid, cumene hydroperoxide, perbenzoic acid 
and p-menthane hydroperoxide, oxyacids and salts thereof such as iodic 
acid, sodium and potassium iodates and sodium and potassium chlorates, 
metal salts such as iron(III) chloride, copper sulfate, copper(II) 
chloride and lead acetate, ozone and metal oxides such as copper oxide, 
mercury oxide, cerium oxide, manganese dioxide and osmic acid. Iron(II) 
chloride and copper(I) chloride may be used. It is sometimes advantageous 
that a small amount of iron(II) chloride is used in combination with 
hydrogen peroxide. 
(2) According to U.S. Pat. No. 4,528,336, Condensation product I and XXI 
were prepared as described below. 
A mixture composed of 1.00 mole of aniline, 0.227 mole of nitrobenzene, 
0.310 mole of hydrochloric acid in the form of a 35% aqueous solution and 
0.103 mole of iron(III) chloride was heated first at 60.degree. C. for 6 
hours followed by temperature elevation up to 180.degree. C. to 
185.degree. C. where the mixture was kept with agitation for 15 hours with 
continuous distilling off of water. The aniline and nitrobenzene distilled 
out as accompanied by the water were returned to the reaction vessel 
during the reaction. Thereafter, the temperature of the reaction mixture 
was further increased to 200.degree. C. and agitation was continued at 
this temperature for further 5 hours to complete the condensation 
reaction. 
The thus formed reaction product in a molten state was poured into a large 
volume of a diluted hydrochloric acid and heated at 60.degree. C. for 3 
hours. The mixture was then filtered while it was still hot to remove the 
unreacted aniline in the form of the hydrochloride dissolved in the 
aqueous phase and the filtered cake was washed 5 to 6 times with water to 
remove the hydrochloric acid followed by drying to give the condensation 
product. The yield of this product was 45.2% of the total amount of the 
aniline and nitrobenzene. This product is called the Condensation product 
I hereinafter. 
Condensation Products II to XX were prepared each in a similar manner to 
the preparation of the Condensation Product I with the formulation as 
indicated in Table 4 below for the aromatic amine compound, aromatic nitro 
compound, mineral acid and condensation catalyst as well as the amounts 
thereof. Table 4 also gives the yields of the respective condensation 
products calculated on the total amounts by weight of the aromatic amine 
and nitro compounds. 
Further, Condensation Product XXI was prepared in a following manner. Thus, 
a mixture composed of 1,00 mole of aniline and 0.310 mole of 35% 
hydrochloric acid was chilled at 10.degree. C or below and, after admixing 
of 0.103 mole of iron(III) chloride, heated to a temperature of 60.degree. 
C. where it was agitated for 6 hours to effect the condensation reaction 
of aniline alone. The temperature of this reaction mixture, without 
removing the unreacted aniline, was increased to 170.degree. C. to distil 
out water and, while keeping the mixture at this temperature, 0.227 mole 
of nitrobenzene was added to the reaction mixture over a period of 6 hours 
followed by rapid temperature increase up to 180.degree. C. to 185.degree. 
C. where the reaction was continued for 15 hours. During this reaction 
period, water formed by the condensation reaction was distilled out 
together with small volumes of aniline and nitrobenzene and the aniline 
and nitrobenzene were separated from water and returned to the reaction 
vessel. Thereafter, the temperature of the reaction mixture was further 
increased to 200.degree. C. and the reaction was completed by agitating 
the reaction mixture for additional 5 hours at this temperature. 
The thus obtained reaction product in a molten state was poured into a 
large volume of a diluted hydrochloric acid and heated for 3 hours at 
60.degree. C. followed by filtration while the mixture was still hot to 
remove the unreacted aniline dissolved in the aqueous phase. The filtered 
cake was washed 6 times with water to remove the hydrochloric acid 
followed by drying to give the condensation product. The yield of this 
condensation product was 39.2% based on the total amount of the aniline 
and nitrobenzene initially used. 
TABLE 4 
______________________________________ 
Con- 
den- 
sation- 
Aromatic Aromatic Conden- 
Pro- amine nitro Mineral 
sation 
duct compound compound acid catalyst 
Yield 
No. (moles) (moles) (moles) 
(moles) % 
______________________________________ 
I Aniline Nitro- Hydro- Iron(III) 
45.2 
(1.00) benzene chloric 
chloride 
(0.227) (0.310) 
(0.103) 
II 4-Methyl- Nitro- Hydro- Ammonium 
40.5 
aniline benzene chloric 
persulfate 
(1.000) (0.262) (0.358) 
(0.118) 
III Aniline Nitro- Hydro- Ammonium 
53.1 
(0.349) + benzene chloric 
persulfate 
1,4- (0.407) (0.334) 
(0.088) 
phenylene- 
diamine 
(0.370) 
IV 4-Methyl- Nitro- Hydro- Ammomiun 
45.0 
aniline benzene chloric 
persulfate 
(0.630) + (0.330) (0.452) 
(0.089) 
4-amino- 
diphenyl- 
amine 
(0.370) 
V Aniline Nitro- Hydro- Ammomiun 
55.3 
(0.664) + benzene chloric 
persulfate 
4-amino- (0.402) (0.297) 
(0.098) 
diphenyl- 
amine 
(0.336) 
VI Aniline 2-Nitro- Hydro- Ammomiun 
38.7 
(0.605) + phenol chloric 
persulfate 
4-chloro- (0.162) (0.270) 
(0.074) 
1,2- 
phenylene- 
diamine 
(0.395) 
VII Aniline 4-Nitro- Hydro- Ammomiun 
60.2 
(0.540) + phenol chloric 
persulfate 
2-amino- (0.217) (0.496) 
(0.044) 
phenol- 
(0.460) 
VIII Aniline 4-Nitro- Hydro- Hydrogen 
57.1 
(0.500) + phenetole chloric 
peroxide 
3-amino- (0.241) (0.496) 
(0.296) + 
phenol iron(II) 
(0.500) chloride 
(0.004) 
IX Aniline 2-Nitro- Sulfuric 
Hydrogen 
48.9 
(0.809) + phenol (0.498) 
peroxide 
4-amino- (0.116) (0.443) + 
phenol iron(II) 
(0.191) chloride 
(0.006) 
X Aniline 2-Amino- Sulfuric 
4-menthane 
45.0 
(1.000) nitro- (0.462) 
hydro- 
benzene peroxide 
(0.222) (0.162) 
XI Aniline 3-Nitro- Hydro- Sodium 36.7 
(0.682) + anisole chloric 
iodate 
4-amino- (0.290) (0.296) 
(0.118) 
4'-hydroxy- 
diphenl- 
amine 
(0.318) 
XII Aniline 2-Chloro- Hydro- Sodium 40.5 
(0.607) + nitro- chloric 
chlorate 
2-amino-4- 
benzene (0.263) 
(0.239) 
chloro- (0.215) 
phenol 
(0.393) 
XIII Aniline 4-Nitro- Hydro- Dibenzoyl 
30.5 
(0.578) + benzoic chloric 
peroxide 
4-chloro- acid (0.310) 
(0.107) 
aniline (0.148) 
(0.422) 
XIV Aniline 3-Nitro- Hydro- Copper(II) 
42.0 
(0.278) + phenol chloric 
chloride 
4-methyl- (0.335) (0.298) 
(0.126) 
aniline- 
(0.772) 
XV 4-Amino- 4-Nitro- Hydro- Manganese 
52.1 
diphenyl- benzene- chloric 
dioxide 
amine sulfonic (0.393) 
(0.330) 
(0.370) + acid 
1,3- (0.243) 
phenylene- 
diamine 
(0.630) 
XVI 4-Amino- 4-Amino- Hydro- Iron(III) 
55.3 
diphenyl- nitro- chloric 
chloride 
amine benzene (0.393) 
(0.096) 
(0.400) + (0.296) 
1,2- 
phenylene- 
diamine 
(0.600) 
XVII Aniline 4-Chloro- Hydro- Ammonium 
47.1 
(0.538) + nitro- chloric 
persulfate 
1,2- benzene (0.286) 
(0.132) 
phenylene- 
(0.203) 
diamine 
(0.462) 
XVIII Aniline Nitro- Hydro- Iron(II) 
40.1 
(1.000) benzene chloric 
chloride 
(0.227) (0.310) 
XIX Aniline Nitro- Hydro- Iron 20.1 
(1.000) benzene chloric 
(III) 
(0.060) (0.310) 
chloride 
(0.103) 
XX Aniline Nitro- Hydro- Iron 40.1 
(1.000) benzene chloric 
(III) 
(0.755) (0.310) 
chloride 
(0.103) 
______________________________________