CA1118943A - Method for the polymerization of vinyl chloride - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

In the polymerization of monomeric vinyl chloride alone or admixed with another copolymerizable monomer or monomers, deposition of polymer scale can be prevented by coating or treating, prior to polymerization, the surfaces of the inner wall and other parts of a polymerization vessel coming into contact with the monomer or monomers with at least one compound selected from polar organic compounds and organic dyes and at least one selected from the halides, hydroxides, oxides and carboxylates of any metallic elements and oxoacids and inorganic salts thereof of elements belonging to pre-determined groups of the Periodic Table.

Description

This invention relates to a method for polymerizing vinyl chloride monomer or a monomeric mixture composed mainly of vinyl chloride and, more particularly, to a method for preventing deposition of polymer scale on the inner wall o the polymerization vessel concerned and other surface~ in contact with the monomer or monomeric mixture.
In any known type of polymerization, such a~, sus-pension polymerization, emulsion polymerization, solution polymerization, gas phase polymerization and bulk polymerization, the deposition of polymer scale on the inner wall of a poly-merization vessel and other surface~ in contact with a monomer or monomers has been a serious problem for the following reasons. Firstly, the polymer scale deposition causes decreases in the yield of polymer product and the cooling efficiency of the polymerization vessel. Secondly, any scale coming off the surfaces can become mixed in the polymer product, result-ing in deterioration of its quality. Thirdly, the removal of scale deposition, or the descaling of the suraces, requires ., much labor and time, resulting in a reduction of productivity. ~;

~:; 20 Lastly and as a matter of very importance of late, the descaling operation usually carried out following every polymerization : run involves a health problem to workers due to any unreacted `~ monomer or monomers that have been adsorbed on the scale.
.
`~ For the prevention of polymer scale deposition on the various surfaces, there have been proposed some methods which compri~e coating tho~e surfaces with polar organic ~ compounds, such as, amine compounds, quinone compounds and : .
' aldehyde compounds, dyes and pigments. ~See Japanese Patent ;~., .;
~, Publications Nos. 30343/1970 and 30835/1970.) However, the prior art techniques have not been found effective in a poly-merization process in which vinyl chloride is polymerized in ~,."~'.

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the presence of emulsifying agents or in combination with a comonomer or comonomers, or where the polymerization mixture contains acyl peroxides, such as, ben70yl peroxide, lauroyl peroxide and the like or higher carboxylic acids, such as lauric acid and stearic acid or salts thereof. Further, .
according to the prior art techniques, the effect of scale prevention can hardly be maintained for repeated polymeriza-tion runs.
It is therefore a primary object of this invention - 10 to provide a method for the polymerization of vinyl chloride or a monomeric mixture composed mainly of vinyl chloride, ; according to which the deposition of polymer scale on the ~; inner walls of a polymerization vessel and other surfaces in ;~
-~ contact with the monomer or monomers can be substantially pre-vented in all types of polymerization.
~: Another object of the present invention is to provide - a method for the polymerization of vinyl chloride or a monomeric mixture composed mainly of vinyl chloride, according to which the productivity of vinyl polymer can be much enhanced.
Still another object of the present invention is to provide a method for the polymerization of vinyl chloride or a monomeric mixture composed mainly of vinyl chloride, according ~ `
to which high quality vinyl polymer can readily be produced.
,~.! In accordance with one embodiment of this invention ~ there is provided a method for the polymerization of vinyl ,,. li ~
chloride monomer alone or admixed with a copolymerizable monomer .
. ,~
or monomers in the presence of a polymerization initiator, which ~- comprises treatiny, prior to polymerization, the surfaces of the `;A' inner walls and other parts of the polymerization reactor coming into contact with the monomer or monomers with (a) at least one . i~ ,. .

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organic compound selected from the yroup consisting of organic dyes and polar ~rganic compounds except polymeric imines; and (b) at least one compound selected from the group consisting of halides, hydroxides, oxides and carboxylates of any metallic elements and oxoacids o~ those i~lem~nts which belong to the second to sixth periods of groups IIs ar.d III through VII of - -the Periodic Table and inorganic salts of the oxoacids, The above-mentioned polar organic compounds as compounds (a) are exemplified by the following.
(1) Nitrogen-containing organic compounds selected from the compounds having an amino, imino, azo, nitro, nitroso or azomethine group or an azine ring and amine, imine and quaternary . .
.
.`~ ammonium compounds, e.g., azomethane, azobenzene, .., ~i~ nitrobenzene, nitrosobenzene, monoaminomono-....
nitroazobenzene, pyzazine, pyridine, thiazine, aniline, oxazines (morpholine etc.) benzal aniline, EDTA,~ - and ~ -naphthyl amines, ethanol amine, diethanol amine, toluidine, Methylene Blue, Nigrosine Black, Oil Black, Spirit Black, diaminonaphthalenes, diphenyl ' amine, hydrazine, N, N-dimethylaniline, urea, laurylamine, cetyltrimethyl ammonium chloride, ~'` polyamides and polyethylene imines.
~ (2) Sulfur-containing organic compounds selected - from the compounds having a thiocarbonyl, thioether or thioalcohol group, e.g., . ;-:
~` thioglycolic acid, thiourea, thiocaxbanilic acid, thiocarbamic acid, thiobenzoic acid, thioethers represented by the general formula `~ R-S-R'(where R and R', which may be the same ,''., ~ 3 ~

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9~3 .` or different, each represent an alkyl group), . such as, dimethylsulfide and ethylmethylsulide, ::~ and mercaptans, such as, propylmercap~an and butylmercaptan, polysulfide , polysulfones : and sulfonic acids, such as, p-toluensulfonic acid, cyclohexylsulfonic acid, a-naphthalene-sulfonic acid, anthraquinonesulfonic acid, metanilic acid, dodecylbenz~nesulfonic acid, and salts thereof with alkali metals, such as, 10 sodium and potassium.
:~ (3) Oxy:yen-containing organic compounds selected from quinones, ketones, aldehyde~, ethers, alcohols and alkali salt~ thereof, esters, carboxylic acids and salts thereof, sulfoxides and oximes, e.g., p-ben~oquinone, anthra~uinone, : benzophenone, acetophenone, diisopropylketone, formaldehyde, acetaldehyde, benzaldehyde, . ~ .
octyl alcohol, cetyl alcohol, benzyl alcohol, .:; phenol, cresol, hematein, propargyl alcohol, ~ i , hydroquinone, ~luorescein, ethylene glycol, .~ pentaerithritol, glucose, sucro~e, polyvinyl : ` .
~ alcohol, diisopropyl ether, diphenyl ether, `~ cellulose ethers, amylacetate, ethylbenzoate, stearic acid, benzoic acid, salicy~ic acid, .~' maleic acid, oxalic acid, tartaric acid, ,` Rochelle salt, succinic acid, malic acid, isonicotinic acid, phenylglycine, 3-oxy-2-. ~ ~
~ ` naphthoic acid, gallic acid, polyacetals and `~

~. -poIyacrylic acid.

; 30 (4) Phosphorus-containing organic compounds ~ selected from the phosphoric and polyphosphoric .
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~,`' ~` acid esters and alkali metal or ammonium salts :: thereof, e.g., monolauryl phosphate, sor~itan hexametaphosphate, polyoxyethylene sorbitan ~ triphosphate and phytic acid.
.~:j (5) Tars, pitches, rosins and waxes with an undefined chemical structure.
Futhur, the o~ganic dyes a~ compounds (a) are exemplified by the following.
. Azo dyes, such as, monoazo dyes, polyazo dyes, metal-containing azo dyes, naphthol dye~ (azoic dyes and ~ inactive dyes) and dispersed azo dyes; anthraquinone .. dyes, such as, anthraquinone acid dyes, anthraquinone .~. vat dyes, anthrone vat dyes, alizarin dyes, and - dispersed anthraquinone dyes; indigo dye~, such as, `. Brilliant Indigo B, Threne Red Violet ~H and Threne ~: Printing Black B; sulfide dyes, such as, Sulfur ~.
Blue FBB and Sulfur Black B and Sudan B;
.. phthalocyanine dyes, such a~, copper or metal-free -; phthalocyanine compounds, diphenylmethane or ~ ~ .
.i 20 triphenylmethane dye~, nitro dyes, nitroso dyes,. i :
.. . .
thiaæole dyes, xanthene dyes, acridine dyes, azine dyes, oxazine dyes, thiazine dyes, benzoquinone and naphthoquinone dyes, and cyanine dyes; and water-soluble organic dyes, such as Direct Brilliant :
Yellow G (direct dye), Acid ~ight Y~llow 2G (acid dye), Levafix Yellow 4G (reactive dye), Procion Brilliant Orange G (reactive dye), Direct Fast :;
Scarlet GS ~direct dye), Direct Bordeaux NS (direct ~;~
dye), Brilliant Scarlet 3R (acid dye), Acid Alizarine :.
Red ~ (acid mordant dye), Direct Turkish Blue GL
(direct dye), Cibacron Blue 3G (reactive dye), . ~:.

Blankophor B (acid dye), Nigrosine (acid dye), Sirius G (direct dye), Chrysamine G (direct dye), Direct Fast Yellow GG (direct dye)~ Chrome Yellow G ~acid mordant dye), Chrome Yellow ME (acid mordant dye), Eosine G (acid dye), Basic Flavin 8G (basic dye), Astrazon Yellow 3G (basic dye), Rhod~mine 6GCP (basic dye), Safranine T (basic dye), Rhodamine B (basic dye), Daitophor AN (basic dye), Auramine Conc (basic dye), Chry~oidine (ba ic dye) and . ~ .
Bismarck Brown BG (basic dye).
~ The above polar organic compounds and organic dyes ~ can be used alone or in combination.
. Next, the compounds a~ compounds (b) useful in the method of the present invention, on one hand, are sele~ted .. fxom the halides, oxides, hydroxides and lower carboxylates of the metallic elements which are exemplified by alkali metals, such as, sodium and potassium, alkaline ear~h metals, .. such as magnesium, calcium and barium, metals of the zinc .~ group, such as, zinc, metals of the aluminum group, such as, ~: .
20 aluminum, metals of the tin group, such as, titanium and tin, metals of the iron group, such as, iron and nickel, metals of ` the chromium group, such as chromium and molybdenum, metals of the manganese group, such as manganese, metals o~ the copper group, such as copper and silver and metals of the ~ !
platinum group, such as, platinum. Illustrative of these com- ~.
.` pounds are sodium fluoride, sodium acetate, ferrous chloride, calcium chloride, potassium chloride, ~odium tartrate, sodium chloride, calcium actetate, titanium dioxide, sodium oxalate, aluminum chloride, :cupric chloride~, man~anese dioxide, iron octoate and stannic chloride.
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~ Compounds (b), on the other hand, ara selected from . . , ;~: oxoacids of the elements belonging to the ~econd to sixth periods of groups IIB and III through VII of the Periodic .-................................. -- 6 --," ~ , :

Table and inorganic salts of the oxoacids.

Illustrative of the elements are zinc, boron, alu-~,:
~- minum, carbon, silicon, tin, tit.anium, nitrogen, phosphorus, . . , s sulfur, chromium, molybdenum, tungsten, chlorine and manganese.

Illustrative of the oxoacids and salts thereo~ are ,.~
`' the following: Zincic acid, bori~ acid, aluminic acid, carbonic acid, silicic acid, stannic acid, titanic acid, phosphoric acids (including dehydrated and condensed phosphoric acids, such as, metaphosphoric acid, pyrophosphoric acid and tri-polyphosphoric acid), nitric acid, sulfuric acid, chromic acid, molybdic acid, tungstic acid, manganic acid, chloric acid as well as permanganic acid and bichromic acid in higher oxidation state, nitrous, hyponitrous, phosphorous, hypophosphoxic and hypophosphorous acids in lower oxidation state, and salts of the above oxoacid~ with ammonium, alkali metals or alkaline earth metals.
In carrying out the method of the present invention, it is advantageou~ that compounds (a) and (b) are dissolved ;- or dispersed separately or in combination in a solvent prior to application. The solvents generally used are water, alcoholic solvents, ester solvents, ketone solvents, hydrocarbon solvents and chlorinated hydrocarbon solvents.
The following are three preferred embodiments in accordance with the method of the invention.
Firstly, compound (a) is dissolved or dispersed in .: , . ::
. ~
~: one of the above-mentioned solvents, and the re~ulting solution or dispersion is applied over the surfaces of the inner wall and other parts of the polymerization reactor coming into contact with the monomer or monomers. Then the coated surf~ces .. ,. ~
are contacted and treated with compound tb) by putting it~

~;l solution or disper~ion into the reactor, heating the solution ~ 7 : ,, ~ . , .
.. . . .. . .. ..
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or dispersion desirably at 50 to 100C for lO minutes ox more and, thereupon, withdrawing the solution or dispersion from ~ the reactor, followed by a conventional polymerization pro--- cedure ~ith the same reactor. In this ~ase, however, if the polymerization mixture is aqueous as in, for example, su~pen-sion or emulsion polymeri~ation, and if the solvent used to form the solution or dispersion of compound (b) is water, then it is not always required to withdraw the heated aqueous solution or dispersion.
., Secondly, compound (a) is dissolved or dispersed in a suitabl~ solvent, while compound (b) is di~solved or dispersed in the same or different solvent. The solution or dispersion of compound (a) is added dropwise to that of compound (b~, followed by heating in a range of from 50 to 100C. The resulting mixture is applied over the surfaces ;~ of the inner wall and other parts of a polymerization reactor coming into contact with the monomer or monomers. ~he thus coated surfaces are then washed with water, if necessary.
Thereupon, polymerization is commenced by a conventional pro-redure.
Thirdly, separa~e solutions or dispersions of `~ compounds (a) and (b) are prepared in the same or different solvents. The (a) solutions or dispersions and (b) solutions or dispersions are alternately applied one or more times over the surfaces coming in contact with the monomer or monomers.
The thus coated surfaces are subjected to heat treatment by passing hot water through a jacket of the reactor or blowing hot air into the reactor. It is preferred to perform the ; application of the coating solutions or dispersions while the inner wall is kept at about 50 to 100C by passing hot water through the jacket. It is more preferable to complete : ., ' ' i . .,. , , ' `:

9f~3 the application of the solutions or dispersions by passing hot water through the jacket and simultaneously blowing hot air into the reactor at every instance of the application or ~!'" coating.

~"~ In any of the above embodiments it is advantageous that compounds ~a) and (b) be brought into contact with each - other at an elevated temperature higher than 50C. If such ~- temperature is lower, no satisfactory result i~ obtained and ~ more than 10 hours are required for the treatment.
: 10 The ratio of compound (b) to compound (a) used in accordance with the method of the present invention may vary depending on the kinds of compounds used and the type of polymerization, concerned. Specifically in the above-described ~- first embodiment in which compound (b) has a low concentration in an aqueous phase and in the third embodiment in which compounds (a) and (b) do not mix well with each other, the ratio of compound tb) to compound (a) is preferred to be relatively large or, generally, from 0.1:1 to 500.1 by weight.
In the second embodiment in which the heated mixture of compounds (a) and (b) is applied, the ratio of compound (b) to compound (a) can be relatively small, say, from 0.01:1 to 50:1 by weight.
In accordance with the present invention, the amount of compound (a) or (b) or the mixture thereof to be used ~or ` coating the surfaces of the inner wall and other parts of the ~, reactor may be more or les~ the same as in ca~es where con-ventional coating materials are used according to the prior : ., .
art techniques. For example, sufficient prevention of polymer scale deposition can be accompli~hed with an amount of at least 0.001 g/m2.

It may be added in connection with the above-~' , ~ 9 -~1~8~'~3 described three embodiments that it is of course optional to employ any of them not only singly but also in combination.
For example, the surfaces are coated first with a mixed solution of compounds (a) and (b), followed by heating as in the second embodiment and the thus coated surfaces are over-coated with a solution of compound (a) and a solution of compound (b) in succession, followed by heating a~ in the third embodiment.
Further, when two kinds of compound (a) are employed in combination, it is possible in some cases to ~btain bet~er results by selecting one of the two compounds from water-soluble ones and the other from organic-soluble ones.
Furthermore, it is useful for attaining better scale preventing effects to add to the polymerization mixture : . ~
concerned a solution or dispersion of compound (a) or (b) or a mixed and heàted solution or dispersion of compound (a) and (b). In this case, the amount of such addition should be restricted to the range o from several p.p.m. to 100 p.p.m.
based on the monomer or monomers used, for excessive amounts may possibly cause adverse effects to the resultiny polymer ;;
product.
In order to futher enhance the prevention of scale ; deposition in accordance with the present invention, it is :.
proposed to add to the polymerization mixture an alkaline ; substance, though not in conformity with the definition of compound (b~, such as, oxides, hydroxides, carbonat~s, phosphates, bicarbonates, silicates and acetates of alkali ~ metals, al-kaline earth metals and ammonium. However, it i~
i important that the alkaline substance should be added in an amount such that will not work to deteriorate the resulting polymer. A suitable amount is, for example, up to 1~ by ,,.,, , ~ , - 10 -.. . .

~".Y.
weigh-t based on the monomer or monomeric mixture.
The method of the present invention can be applied to all types of polymerization, i.e., suspension polymerization, ; emulsion polymerization, solution polymerization and bulk -~ polymerization, of vinyl chloride monomer or a monomeric mixture composed mainly of vinyl chloride. Fur~her, ~he method of the invention does not place any limitations on the kinds of various additives, such as, suspending agents, ~- emulsifiers and chain transfer agents, polymerization initiat-` 10 ors, polymerization temperature and the velocity of agitation.
-~ The method of the invention may be applied effect-ively to not only homopolymerization of vinyl chloride but also copolymerization of vinyl chloride with a copolymerizable monomer or monomers. Examples of the copolymerizable monomers are, vinyl esters, vinyl ethers, acrylic and methacrylic acids and esters thereof, maleic and fumaric acids, esters thereof, ~ maleic anhydride, aromatic vinyl monomers, vinyl halides -~ other than vinyl chloride, vinylidene halides, olefins, acrylonitrile and methacrylonitrile.
This invention will further be illustrated by the ~' following examples.
Example 1.
For the purpose of this example, 2-liter stainless steel autoclaves, each equipped with a turbine agitator were provided. The surfaces of the inner wall of each autoclave ~-and the agitator blades were coated with a 0.1% solution -~ in toluene of each of the various organic dyes as indicated under heading "Compound A" in ~able I in an amount of about 0.05 g/m2 ~as solid), and the coated surfaces were dried at 70 for 60 minutes, whereupon a 1% aqueous solution of each ~
of the various oxoacids or salts thereof as indicated under ~-; :
'.

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heading "Compound B" in the same table was applied over the coated and dried surfaces in an amount of about 0.05 g/m - (as solid), following by drying at 70C for 60 minutes. Then into each autoclave thus coated were put 900g of water, 0.4g of methylcellulose and 0.8g of polyvinyl alcohol. After the autoclave was evacuated of air and filled with nitrogen instead, 600g of vinyl chloride monomer and 0.21g of ~,a'-azobisdimethyl valeronitrile were charged and the mixture was subjected to suspension polymerization at an agitating velocity of 1,000 r.p.m. and a temperature of 57C for about 6 hours. The polymerization runs wexe continuously repeated with each autoclave until scale deposition exceeded 1 g/m , the numbers o~ such repeated polymerization runs being - - mentioned in Table I under the heading "No. of Runs". The No. of Runs means, in other words, that scale deposition was effectively prevented during those repeated polymerization runs. The details and results are set out in Table I.
For comparative purposes, tests using Compound A
or B alone, not in combination, were carried out in and under similar manners and conditions, obtaining the results as set out in the same table.

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.: Table I
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~:~ Compounds Compound Compound A and B A B
.
Compound Compound ~est No. of Test No. of Te~t No. of A B No. Run No. Run~ No. Runs ~: Nigrosine Sodium .~ Black silicate 1 18 1312 25 2 Spirit Potassium . Black nitrite 2 12 149 26 2 Oil Black Boric acid 310 15 7 27 Threne Silicic Grey K acid 4 5 163 28 2 . ' ~
Aniline Pota sium ; Black bichromate 5 617 4 29 ~: Alizarine Tripoly-Yellow R phosphoric 6 618 2 30 2 acid :; Fa~t Light Magnesium Yellow G carbonate 7 4 19 3 31 , . . .
Threne Stannic .-Golden acid 8 3 202 32 1 . Yellow RK
I Pyrazolone Sodium Red molybdate 9 3 212 33 2 ,.
Permanent Titanic ;~ Orange GTR acid 10 3 222 34 Phthalocy~ Permanga-anine Blue nic acid11 223 1 35 ' Naphthol Sodium -:,~
! Yellow S borate 12 3 242 36 1 : :~
: Note: Tests numbered 13-36 are controls. ;;
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' r 8~3 Example 2.
The same autoclaves as us~d in Example 1 were coated with Compounds A and B in combination as indicated in Table ~ and, for comparative purposes, with compound A
. or B alone as indicated in the same table, in and under the same mann~r and conditions as in Example 1. Into each of the coated autoclaves were charged 900g of water, 6g of sodium lauryl sulfonate, lg of potassium persulfate and 600g of vinyl chloride, to carry out emulsion polymeriza-.; 10tion at 48C for 10 hours. The details and results of these tests are tabulated as follows.

. Table ~

: No. of .: Test No. Compound A Com~ound B Runs `~ 37 Nigrosine Black Txipolyphosphoric acid 5 38 Spirit Black Sodium molybdate 3 39 Oil Black Sodium nitrite 2 . 40 Nigrosine Black Sodi~m silicate 5 20 41 Spirit Black Boric acid 3 .~. - 42 Nigrosine Black -- 3 :;: 43 Spirit Black -- 2 44 -- Sodium silicate ~: 45 -- Sodium nitrite 46 ~- Phosphoric acid 1 :~

..
,. .
,: Note: Tests numbered 42-46 are controls.

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Example 3.
The same autoclaves as used in Example 1 were coated with Compounds A and B in combination as ind-icated in Table III and, for comparative purposes, with compound A or B alone as indicated in the same table, in and under the same manner and conditions as in Example 1. Into each of the coated autoclaves were charged 900g of water, 0.4g of methyl cellulose, 0.8g of poly-vinyl alcohol, 600g of vinyl chloride, and 60g of a comonomer, i.e., vinyl acetate or vinylidene chloride, ,.~
.;.-;~ and 0.21g of isopropyl peroxydicarbonate to carry out .` suspension polymerization at 52C for about 6 hours. The -~ details and results of those are set out in Table III.
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~: - 15 -: Table III
' Test No. of No. Comonomer Compound A Compound B uns ~ 47 Vinyl Nigrosine Black Silicic acid 8 : acetate 48 " Oil Black Tripolyphos- 5 phoric acid 49 " Nigrosine Black Potassium 7 nitrite " Oil Black Boric acid 4 51 Vinylidene Nigrosine Black Phosphoric 8 chloride acid 52 " Spirit Black Sodium 5 molybdate 53 " Nigrosine Black Potassium 8 silicat~
54 Vinyl Nigrosine Black -- 5 acetate ~: 55 " Oil Black -- 3 '~ :
: 56 " -- Silicic acid 57 " -- Tripolyphos-` phoric acid . 58 Vinylidene Nigrosine Black -- 5 chloride .. 20 :`- 5g " Spirit Black -- 3 " -- Sodium molybdate . ~, .

.~ Note: Tests numbered 54-60 are controls. :`
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Example 4.
The same autoclaves as used in Example 1 were : coated with a 0.05% solution or dispersion of a mix-ture consisting of Compounds A and B in equal amounts .: but in varied combinations as indicated in Table IV in an amount of 0.1 g/m2 (as solid), and the coated sur-faces were dried at 70C for 60 minutes. Then, the suspension polymerization of vinyl chloride was carried - . out in and under the same manner and conditions as in Example 1, to test for scalei deposition. The details and results are set out in Table IV.

. ~ , Table IV

- Test . No. of No. Com~ound A Compound B_ _~uns : 61 Nigrosine Black Sodium borate 16 : 62 Spirit Black ~otassium Nitrite 12 63 Oil Black Silicic acid 11 -~-. 64 Threne Grey K Boric acid 5 j~ 20 65 Aniline Black Tripolypho~phoric 6 .. - acid :
66 Alizarine Potassium 5 `:
Yellow R bichromate -`~

~`~ 67 Fast Light Stannic acid 3 ~
:~ Yellow G ::

68 Threne Golden Sodium silicate 3 ` ~
, Yellow RK `:

69 Pyrazolone Red Titanic acid 3 ~,~

Permanent Permanganic 2 `~
Orange GTR acid : 71 Phthalocyanine Phosphoric . 4 Blue acid :

- 30 72 Napthol Sodium 3 Yellow S molybdate ` ~` ' .~ :
.;' .~
~ 17 -.''-'''' ' ;

Example 5.
' The same au~oclaves as used in Example 1 were coated with Compounds A and B in combinations as indicated in Table V in and under the same manner and conditions as in Example 4. With each of the coated autoclaves, emulsion polymerization similar to ~hat of Example 2 was carried out. The details and results of : these tests are set out in Table V.
:

Table V

.-: Test No. of No. ComRound A Compound B Runs : 73 Nigrosine Black Tripolyphosphoric 4 acid -~ 74 Spirit Black Sodium molybdate 2 .- 75 Oil Black Sodium nitrite 2 . 76 Nigrosi~e Black Sodium silicate 4 ;;

,. 77 Spirit Black Boric acid 2 c ~
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Example 6.
The same autoclaves asused in Example 1 were ~ coated with Compounds A and B in combination as : indicated in Table VI in and under the same manner and conditions as in Example 4. With each of the coated autoclaves, suspension polymerization or copolymeriza-~; tion substantially similar to that of Example 3 was carried out. The details and results of the tests are set out in Table VI.

Table VI

~- Test No. of ,~ No. Compound A Compound BRuns ~ 78 Nigrosine Black Silicic acid 7 .~ .
; 79 Oil Black Tripolyphosphoric 5 acid Nigrosine BlackPotassium nitrite 7 81 Oil Black Boric acid 4 82 Nigrosine BlackPhosphoric acid 6 . 83 Spirit Black Sodium molybdate 5 `~, 84 Nigrosine BlackPotassium silicate 6 ~, .~

Note: Test Nos. 78-81 are of the homopolymerization of vinyl chloride.
:~ Test Nos. 82-84 are of the copolymerization of -~ vinyl chloride and vinylidene chloride. :~

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Example 7.
The same autoclaves as used in Example 1 were coated with a solution of Nigrosine Black in ethanol or tol-uene in the varied amounts as indicated in Ta~le VII, follow-ed by drying at 70~C or 60 minuteQ, and, thexeupon, a 1%
aqueous solution of sodium silicate was applied over the - ~ coated and dried surfaces in an amount of 0.05 g/m2 (as æolid), follcwed by drying at 70C for 60 minutes. Th n, with each of the coated autoclaves, the suspension polymerization of vinyl chloride was carried out in and under the same manner and con-, . .
ditions as in Example 1 to test for scale deposition. The details and results are set out in Table VII.

'~ Table VII
. ~
Amount of Test Nigrosine Blask No. of No. ~ d ! g~m2 Runs _ : 86 2 3 ~ 87 1 4 .;
" 2088 0.5 5 .
~ 89 0.05 S ~
- :~
~ 90 0.005 3 ; .~ '::
91 0.0005 2 ` 92 0.5 2 `` 93 0.5 6 -;, 94 0.01 3 Notes: ~ Solutions of Nigroslne Black used ~`;'i in Test Nos. 85-91 were in ethanol, while those used in Test Nos. 92-94 were in toluene.

`' 2) In Test No. 93, the surfaces of the ~ 30 Nigrosine Black coatings were t``;,, lightly wiped with a piece of ! ethanol-impregnated cotton gauze ~`, after drying.

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~xample 8.
The same coating and polymerization procedure as taken in Test No. 88 of Example 7 was repeated except that 5% by weight, 0.1~ by weight or 0.0001%
by weight, based on vinyl chloride, of sodium silicate was added to the polymerization mixture before the pol~merization reaction was commenced. As a result, the numbers of polymerization runs during which scale :.~ deposition wa~ prevented were 9, 7 and 5, respectively.
:-~ 10 Example 9.
:.
.. The same procedure as ~aken in Test No. 61 of : Example 4 was repeated except that the coated surfaces were additionally coated with Nigrosine ~lack and sodium silicate in and under the same fashion and con-ditions as in Test No. 1 of Example 1. The number of scale preventing runs of polymerization was 25. ;-.
` Example 10.
For the purpo~e of this example, l,000-liter . stainless steel polymerization ve sels, each equipped with an agitator of the paddle type having blades 600 mm in diameter, ~;
were used. The surfaces of the inner walls of the vessels `~ and the agitator blades and shaft were coated with a 0.5% ;
;; ..
` solution in methanol of a mixture of Sudan B and Nigrosine in the varied mixing ratios by weight as indicated in .. Table VIII in an amount of 0.05 y/m2 (as solid), the ~;` coated surfaces totalling to 4 m2. Into each of the thus .~ coated polymerization vessels were charged 500 kg o~ water, :

- in which one of the various metal 3alts as indicated in Table VIII was dissolved, followed by treatment a~ a temperature shown in the same table under agitation at a :~

,; rate of 110 r.p.m. for 30 minutes, and cooling. Thereupon ~ - 21 ~

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2.2 kg of sodium lauryl sulfate, 3 kg of cetyl alcohol, -. 200 g of dimethyl valeronitrile and 200 kg of vinyl ~ chloride were charged to carry out suspension poly-: merization at 50C for 7 hours in accordance with a conventional method. After the reaction was over, ~` the coated surfaces were washed with water and dried, ; ~ and then the amounts of scale deposition were determined, as set out in Table VIII.
For comparative purposes, similar tests were conducted with Sudan B or Nigro~ine alone and not in combination or without any metal salt. The results .: are shown in the table.

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Test Mixing Ratio Temper- Amount of No. Sudan B/Nigrosine ature MPtal Salt Scale_ : (g/m 95* 100 t 90C Sodium 520 Silicate ,'`~ 10 ~
' 96 100 / 10 " " 5 - 97 100 / 50 " "
-'~'' g8 100 / 100 " " O
' 99 100 / 500 " "
100 100 / 1000 " " 20 101* 0 / 100 " " 780 102 100 / 100 70C " 3 ': 103 100 / 100 50C " 10 104 " 90C Sodium 0 bicarbonate, 20g 105 " " Calcium 0 primary phosphate,20g 106 " " Sodium .. acetate, 20g 0 107 " " Ferrous 0 chloride, 20g .. ~ 108 " " Calcium 0 chloride, 20g : 20 109 " " Potassium 0 :;~ sulfate, 20g 110 " " Alum, 20g 0 ; 111 " " Sodium 0 '~: carbonate, lOg ~.~` 112* 0 / 0 ** (None) 1,800 '`'~ 113* 100 / 0 ** (None) 960 ~`` 114* 0 / 100 ** (None) 1,250 ~`; Notes: *Control.
No heat treatment.
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9~3 Example 11.
The same polymerization vessels as used in Example 10 were coated in a similar fashion with a 1%
solution or dispersion in one of the solvents as indicated in Table IX, of a polar organic compound or an organic dye alone or in combination and with a metal salt as indicated in the same table, which had been heated at 90C for 30 minutes. After the coated surfaces were washed with water, 100 kg of vinyl chloride, 200 kg of water, 0.05 kg of diisopropyl peroxidicarbonate, 1 kg of sodium dodecylbenzenesulfonate and 1.5 kg of cetyl alcohol were charged in each polymerization vessel, ;., i~ followed by emulsion polymerization at an elevated temper-ature, say, 45~C, under agitatlon at a rate of 110 r.p.m.
for 8 hours. After completion of th~ reaction, the `~ amounts of scale deposition were examined and determined.
The results are set out in Table IX.
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39~3 ~- Table IX
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. Test Polar Organic Compd/ Amount of -~ No.... Dye/Metal Salt Mixing Ratio Solvent Scale : (g/m ) 115* (None) --- (None)1,600 116* Sudan B --- Toluene550 .~` 117* Diaminonaphthalene --- Methanol 630 118* Nigrosine Base --- Mixed**480 , ;
: 10 119* EDTA~2Na --- Water1,100 120* Phytic acid --- Methanol 980 121* Methylene Blue --- "690 ~ :
.: 122* Nigrosine --- Water1,300 123 Sudan B/Nigrosine/ 100/ 5/100 Ethanol 23 .-.. ~' Na2SiO4 ` 124 " 100/ 50/100 " O
125 " 100/ 100/100 " O :
126 " lOOjlOOO/100 " 10 '"-` 127 Diaminonaphthalene/ 100/ 100/100 " O
;``.` Nigrosine/NaHC03 128 Nigrosine Base/ " " O
~; 20Nigrosine/NaHC03 .
.~ 129 Methylene Blue/ 30 :
-~- Nigrosine/FeC12 130 Sudan B/Phytic acid/ 63 NaHC03 ' 131 a-Naphthylamine/ " Water 81 EDTA 2Na/Na2S04 ~``` 132 Induline/p-toluene- -:
sulfonic acid/NaCl " Mixed*** 53 133 Oil Brown BB/ :~
Daitophor AN/CaC03 " " 49 ~- 134 Spirit Black/
.~ Rochelle ~alt/Na29iO4 " " O
~
Not~s: * Control.
~` ; ** Toluene and methanol.
*** Ethanol and methylene chloride.
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9~3 ..
Example 12.
The same polymerization vessels as used in Example 10 were coated in a similar fashion with the same material as used in Test No. 126 of Example 11 in an amount of 0.1 g/m2 (as solid)O Into each of the coated vessels were charged 100 kg of vinyl chloride, 200 kg of water to~ether with the varied ini~iators, suspending agents and/or other additives or comonomers as shown in Table X, followed by suspension polymeriz-ation at an elevated temperature, say, 57C, under agitation at a rate of 100 r.p.m. for 10 hours.
After completion of the reaction, the amounts of scale deposition were examined and determined. The results are set out in Table X.
As controls, similar polymerization using the same additives or comonomers as above was carried out . .
with the polymerization vessels which had been coated with a single dye, say, Nigrosine Base or not coated at all. The resulting scale deposition was shown in : 20 the same Table X.
In Table X, PVA represents polyvinyl acetate; HPMC
represents hydroxypropylmethyl cellulose; IPP represents .~,i,~, , ~, di-isopropyl peroxydicarbonate; LPO represents lauroyl peroxide; and BPO represents benzoyl peroxide.

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a3 , ~ Table X ..

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'`: , ;~ Polymer- Amount of Scale Test ization Suspending Additive/ Present No. Initiator Agent Comonomer Invention Control ( g/m2 ) ( g/m2 ) 135 Dimethyl- Partially Vinyl 0 190 . valero- saponified acetate, .:` nitrile, PVA, 15 kg .: 0.03 kg 0.1 kg 136 " " Vinyl 0 130 `i` 10 acetate, '. :'' g ,:
, 137 " HPMC, Sorbitan 0 230 0.1 kg monolaurate, .: 0.1 kg ~ .1' ..... 138 " " Sodium 0 .290 2-ethyl- :
hexylsulfo-succinate, .
`~ 0.1 kg `
.: .:
:~ 139 IPP, Partially ~None) 0 210 :
0.02 kg saponified ~ PVA, 0.1 kg ;~ . 140 LPO
~` 0.5 kg ~ (None) 0 330 141 BPO, ~: 0.7 kg " (None) 0 310 ,~ 142* Dimethyl- " (None) - -1,200 ~ .
` valero- ` :~
~ ; nitrile, .~'.,~`` 0.3 kg ~ Note: * Control. No coating.

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Example 13.
The same coating materials as used in Test No. 129 of Example 11, were applied over the surfaces of the inner walls and other parts in combined vessels for bulk ....
polymerization, the first vessel being of a 2-liter - stainless steel vertical type and the second vessel -~ being of a 4-liter stainless steel horizontal type.

` Then all the coated surfaces were washed with water and ,..i .
~` dried. Into the first vessel were charged 800g of vinyl : ~;
j; 10 chloride and 0.4g of dimethyl valeronitrile, followed by .. . .
- bulk polymerization at 60C under agitation at a rate of 900 r.p.m~ for 2 hours. The reaction mixture was trans-ferred into the second vessel which had been charged ` with 800g of vinyl chloride and 0.4g of dimethyl valero-nitrile. Polymerization was conducted at 57C under agitation at a ra~e of 100 r.p.m. for 10 hours. After ; completion of the polymerization, polymer scale depos-ition was examined with respect to each polymerization ~- - vessel.
'<~; 20 For comparison, a similar test was carried out ; ; without any coating treatment or a coating with only Nigrosine Base.
~`" The results of the above tects are set out in Table XI. ~ ' '`',`.

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Te~t Amount of Scale No. Coating Material 1st Vessel 2nd Vess~l . ~ ( g/m2 )( g/m2 ) : 143 Same as Test No. 125 0 0 ,;~
.. ~ 144Same as Test No. 129 0 0 '!'" 145 Same as Test No. 136 0 0 ~` 146* (None) 1,400 2,040 147* Nigrosine Base 70 180 1 0 ~
Note: * Control.
xample 14.
~- With the same polymerization vessel as coated -. and used in Test No. 126 of Example 11, suspension ` polymerization was carried out in the same manner and . with the same additives aq in Test No. 137 of Example 12 for 10 hours, except that in some tests the coating material of Test No. 126 was separately added to the polymerization mixture in the varied amounts as indicated .~ 20 in Table XII and in the other tests an alkaline substance, say, sodium hydroxide, calcium hydroxide or sodium acetate was added as indicated in the Table. This polymerization run was repeated to observe the deposition of scale by ~:
``~ naked eye or in the same fashion as in Example 1. The .:
. ~
results are set out in Table XII.
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-:''-Amount of Coating Alkaline Subs-~ Test Material tance & Amount Time ofNo. of Z No. Added Added addition* Runs `` (p.p.m.) %
. 148(None) (None) --- 3 ~ . .
.~, 149 10 (None) -- 4 . 150 50 (None) --- 6 ~.~.,.,. ~
.` 151 100 (None) --- 8 - 10 152(None) NaOH 0.01 0 8 .;
: ~ 153(None) NaOH 0.01 1 hr. 6 ".. ` 154 (None) NaOH 0.012 hrs. 5 ~:~. 155(None) NaOH 0.01 3 hrs. 4 156(None) NaOH 0.05 0 10 157(None) NaOH 0.1 o 13 ;
.,, 158(None)Ca(OH)2 0.05 1 hr. 8 :
:
~ 159 50 CH3COONa 0.1 1 hr. 16 :, ` Notes: The amounts in p.p.m. or ~ are based on the weight of vinyl chloride monomer. :' :.
* Number of hours lapsed from the start of each polymerization run.

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Claims (28)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED
AS FOLLOWS:

1. A method for the polymerization of vinyl chloride monomer alone or admixed with a copolymerizable monomer or monomers in the presence of a polymerization initiator, which comprises treating, prior to polymer-ization, the surfaces of the inner walls and other parts of the polymerization reactor coming into contact with the monomer or monomers with:
(a) at least one organic compound selected from the group consisting of organic dyes and polar organic compounds except polymeric imines; and (b) at least one compound selected from the group consisting of halides, hydroxides, oxides and carboxylates of any metallic elements and oxoacids of those elements which belong to the second to sixth periods of groups IIB and III through VII
of the Periodic Table and inorganic salts of the oxoacids.

2. The method as claimed in claim 1 wherein said treatment comprises coating said surfaces with a solution or dispersion of compound (a) and contacting the thus coated surfaces with a solution or dispersion of compound (b).

3. The method as claimed in claim 1 wherein said treatment comprises coating said surfaces with a solution or dispersion of compounds (a) and (b) dissolved or dis-persed in a solvent and heated at a temperature of from 50 to 100°C for more than 10 minutes.

4. The method as claimed in claim 1 wherein said treatment comprises coating said surfaces alternately with a solution or dispersion of compound (a) and with a solution or dispersion of compound (b).

5. The method as claimed in claim 2 wherein the surfaces coated with a solution or dispersion of compound (a) are subjected to heating at a temperature of from 50 to 100°C for more than 10 minutes under contact with a solution or dispersion of compound (b).

6. The method as claimed in claim 4 wherein the surfaces coated with the solution of compounds (a) and (b) are subjected to heating at a temperature of from 50 to 100°C for more than 10 minutes.

7. The method as claimed in claim 1 wherein said treatment comprises at least two of the following procedures:
(i) coating said surfaces with a solution or dispersion of said compound (a) and contacting the thus coated surfaces with a solution or dispersion of compound (b).
(ii) coating said surfaces with a solution or dispersion of compounds (a) and (b) dissolved or dispersed in a solvent and heated at a temperature of from 50 to 100°C
for more than 10 minutes, and (iii) coating said surfaces alternately with a solution or dispersion of compound (a) and with a solution or dispersion of compound (b).

8. The method as claimed in claim 3 wherein the amounts of compounds (b) and (a) are in a ratio of from 0.01:1 to 50:1 by weight.

9. The method as claimed in claim 4 wherein the amounts of compounds (b) and (a) are in a ratio of from 0.1:1 to 500:1 by weight.

10. The method as claimed in claim 1 wherein said treatment comprises coating of said surfaces with at least two compounds (a), one being soluble in water and the other or others being insoluble in water.

11. The method as claimed in claim 1 wherein at least one of compounds (a) and (b) is added to the poly-merization mixture.

12. The method as claimed in claim 1 wherein said polar organic compound is at least one selected from the group consisting of nitrogen-containing organic compounds, sulfur-containing organic compounds, oxygen-containing organic compounds, phosphorus-containing organic compounds, tars, pitches, rosins and waxes.

13. The method as claimed in claim 1 wherein said organic dye is at least one selected from the group consisting of azo dyes, anthraquinone dyes, indigo dyes, sulfide dyes, phthalocyanine dyes, diphenylmethane dyes, triphenylmethane dyes, nitro dyes, nitroso dyes, thiazole dyes, xanthene dyes, acridine dyes, azine dyes, oxazine dyes, thiazine dyes, benzoquinone dyes, naphthoquinone dyes, and cyanine dyes.

14. The method as claimed in claim 1 wherein said organic dye is at least one selected from the group consist-ing of Direct Brilliant Yellow G, Acid Light Yellow 2G, Levafix Yellow 4G, Procion Brilliant Orange G, Direct Fast Scarlet GS, Direct Bordeaux NS, Brilliant Scarlet 3R, Acid Alizarine Red B, Direct Turkish Blue GL, Cibacron Blue 3G, Blankophor B, Nigrosine, Sirius G, Chrysamine G, Direct Fast Yellow GG, Chrome Yellow G, Chrome Yellow ME, Eosine G, Basic Flavin 8G, Astrazon Yellow 3G, Rhodamine 6GCP, Safranine T, Rhodamine B, Daitophor AN, Auramine Conc, Chrysoidine and Bismarck Brown BG.

15. The method as claimed in claim 12 wherein said nitrogen-containing organic compound is at least one selected from the group consisting of compounds having an amino, imino, azo, nitro nitroso or azomethine group or an azine ring, and quaternary ammonium compounds.

16. The method as claimed in claim 12 wherein said sulfur-containing organic compound is at least one selected from the group consisting of compounds having a thiocarbonyl, thioether or thioalcohol group,

17. The method as claimed in claim 12 wherein said oxygen-containing organic compound is at least one selected from the group consisting of quinones, ketones, aldehydes, ethers, alcohols and alkali salts thereof, esters, carboxylic acids and salts thereof, sulfoxides and oximes.

18. The method as claimed in claim 12 wherein said phosphorus-containing organic compound is at least one selected from the group consisting of esters of phosphoric and polyphosphoric acid and alkali metal or ammonium salts thereof.

19. The method as claimed in claim 12 wherein said nitrogen-containing organic compound is at least one selected from the group consisting of azomethane, azobenzene, nitrobenzene, nitrosobenzene, monoaminomononitroazobenzene, pyzazine, pyridine, thiazine, aniline, oxazines (morpholine etc.), benzal aniline, EDTA, .alpha.- and .beta.-naphthyl amines, ethanol amine, diethanol amine, toluidine, Methylene Blue, Nigrosine Black, Oil Black, Spirit Black, diaminonaphthalenes, diphenyl amine, hydrazine, N,N-dimethylaniline, urea, laurylamine, cetyltrimethyl ammonium chloride and polyamides.

20. The method as claimed in claim 12 wherein said sulfur-containing organic compound is selected from the group consisting of thioglycolic acid, thiourea, thiocar-banilic acid, thiocarbamic acid, thiobenzoic acid, dialkyl thioethers, alkylmercaptans, polysulfides, polysulfones and sulfonic acids and salts thereof.

21. The method as claimed in claim 12 wherein said oxygen-containing organic compound is selected from the group consisting of p-benzoquinone, anthraquinone, benzophenone, acetophenone, diisopropylketone, formaldehyde, acetaldehyde, benzaldehyde, octyl alcohol, cetyl alcohol, benzyl alcohol, phenol, cresol, hematein, propargyl alcohol, hydroquinone, fluorescein, ethylene glycol, pentaerithritol, glucose, sucrose, polyvinyl alcohol, diisopropyl ether, diphenyl ether, cellulose ethers, amylacetate, ethylbenzoate, stearic acid, benzoic acid, salicylic acid, maleic acid, oxalic acid, tartaric acid, Rochelle salt, succinic acid, malic acid, isonicotinic acid, phenylglycine, 3-oxy-2-naphthoic acid, gallic acid, polyacetals and polyacrylic acid.

22. The method as claimed in claim 18 wherein said ester of phosphoric and polyphosphoric acids is selected from the group consisting of monolauryl phosphate, sorbitan hexametaphosphate, polyoxyethylene sorbitan triphosphate and phytic acid.

23. The method as claimed in claim 1, wherein said hydroxides, oxides, halides and carboxylates of metal elements are selected from the group consisting of sodium fluoride, odium acetate, ferrous chloride, calcium chloride, potassium chloride, sodium tartrate, sodium chloride, calcium acetate, titanium dioxide, sodium oxalate, aluminum chloride, cupric chloride, manganese dioxide, iron octoate and stannic chloride.

24. The method as claimed in claim 1, wherein said oxoacid is selected from the group consisting of zincic acid, boric acid, aluminic acid, carbonic acid, silicic acid, stannic acid, titanic acid, phosphoric acid, dehydrated phosphoric acids, condensed phosphoric acid, nitric acid, sulfuric acid, chromic acid, molybdic acid, tungstic acid, manganic acid, chloric acid, permanganic acid, bichromic acid, nitrous acid, hyponitrous acid, phosphorous acid, hypophosphoric acid and hypophosphorous acid.

25. The method as claimed in claim 1 wherein said compound (a) or (b) or a mixed and heated solution or dispersion of compounds (a) and (b) is added to the polymerization mixture in an amount not exceeding 100 p.p.m. based on the weight of the monomer or monomers.

26. In a method for the bulk polymerization of vinyl chloride monomer or a mixture thereof with a copolymerizable mono-mer or monomers, the improvement which comprises coating the walls of a polymerization vessel and other surfaces coming into contact with the monomer or monomers, prior to the polymerization, with a mixture of at least one phosphoric compound selected from the group consisting of phosphoric esters, polyphosphoric esters and alkali metal salts thereof and a borate selected from alkali metal borates, alkali earth metal borates and ammonium borate.

27. The method as claimed in claim 26, wherein the amount of said borate is from 0.1 to 50 parts by weight per part by weight of said phosphoric compound.

28. The method as claimed in claim 26, wherein the amount of said mixture is at least 0.001 g/m2.