JPS6140685B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention deals with the polymerization that occurs on the inner surface of the polymerization vessel, stirring blades, buttful plates, and other parts of the vessel when polymerizing vinyl chloride alone or a copolymerizable monomer mixture containing vinyl chloride as the main component. This invention relates to a method for preventing the occurrence and adhesion of coalescent scale. When vinyl chloride alone or a copolymerizable monomer mixture containing vinyl chloride as a main component is suspension polymerized in an aqueous medium in the presence of a dispersant and an oil-soluble catalyst, an aqueous medium is polymerized in the presence of an emulsifier and a water-soluble catalyst. When emulsion polymerization is carried out in a medium or when bulk polymerization is carried out in the presence of an oil-soluble catalyst, there is a problem in that polymer scale is generated and adheres to the inner surface of the polymerization vessel, the stirring blade, the baffle plate, etc. Due to this scale, the heat transfer effect of the polymerization vessel wall is reduced, the product yield is reduced, the quality is degraded due to the inclusion of peeled scale in the product, and the operation of the polymerization vessel is caused by the labor required to peel off the scale and the time required for peeling off. rate decline, etc.
It causes many undesirable disadvantages. In order to solve these problems, many methods for preventing the formation and adhesion of scale have already been proposed, but there are comparatively few methods that have advantages and disadvantages and are practically satisfactory. However, among these methods, the method of pre-coating a certain kind of compound on the inner surface of the polymerization vessel is expected to be an excellent method if a compound with a significantly large effect can be found. Regarding such a method, for example, Japanese Patent Publication No. 45-30343 describes the use of a nitrogen atom-containing organic compound selected from a group having an azo group, a nitro group, a nitroso group, an azomethine group, or an azine ring, and an amine compound, and a thiocarbonyl group. , sulfur atom-containing organic compounds and quinone compounds selected from the group having , thioether groups, and thioalcohol groups, ketone compounds, aldehyde compounds, alcohol compounds with 6 or more carbon atoms, and 6 carbon atoms
It is described that a polar organic compound such as the above-mentioned carboxylic acid compound is applied. However, according to experiments conducted by the present inventors, when the various compounds specifically shown in the specification of the above application are applied, the effect of preventing scale generation and adhesion is extremely weak, and it is not necessarily practical for practical use. I was not completely satisfied. In addition, Japanese Patent Publication No. 45-30835 describes a method of applying dyes and pigments, and some of these substances certainly have excellent effects. However, since dyes and pigments are colored substances intended for coloring, there is a risk of contaminating the polymer product, and this is not necessarily a preferable method. Furthermore, JP-A-48-44375 proposes a method of applying a free radical inhibitor to the inner surface of a polymerization tank. The specification of this application states that particularly good results are obtained when α-methylstyrene is used. However, according to the inventors' experiments,
Almost no effect of α-methylstyrene was observed. As described above, the reality is that it is difficult to say that a satisfactory coating agent for preventing scale formation and adhesion has been found. In order to eliminate these drawbacks, the present inventors have already proposed a polymerization method using a compound having extremely excellent effects in Japanese Patent Application Laid-open No. 13881-1982 or Japanese Patent Application No. 147863-1983 as a result of intensive research. ,
This time, by using a polymer with a completely different structure from conventional coating compounds as a coating agent, we have discovered a new polymerization method that has a remarkable effect of preventing scale formation and adhesion, and have completed the present invention. In the present invention, when polymerizing vinyl chloride alone or a copolymerizable monomer mixture containing vinyl chloride as the main component, the main chain is composed of phosphorus atoms and nitrogen atoms in various parts of the polymerization vessel, such as the inner surface of the polymerization vessel and stirring blades. The feature is that the polymer consisting of the following is applied in advance. According to the present invention, the generation and adhesion of scale can be greatly reduced without impairing the quality of vinyl chloride polymers or copolymers. The interior surface of the polymerization vessel retains its metallic luster even after the process is complete, and the revolutionary result of completely preventing scale formation and adhesion is achieved. The polymer used in the present invention, whose main chain consists of phosphorus atoms and nitrogen atoms, has a molecular structure represented by the following formulas () to (). Here, R and R' are a halogen group, or an aliphatic or aromatic hydrocarbon group with or without a substituent, and R and R' may be the same or different. Further, examples of R and R' include chlorine, bromine, methyl, ethyl, butyl, and phenyl, which can be easily synthesized by known methods. For example, “Chemistry and Industry”
1960, p. 717, or the method described in US Pat. No. 3,169,933. Here, R and R' are aliphatic or aromatic hydrocarbon groups with or without substituents;
It may be the same as or different from R'. Examples of R and R' include methyl, ethyl, butyl, trifluoroethyl, tetrafluoropropyl, phenyl, P-chlorophenyl, m
-tolyl, P-tolyl, naphthyl, etc., which can be easily synthesized by known methods. For example, “Polymer Engineering and Science”
15, p. 321 (1975) or by the method described in "Chemistry and Industry", 1964, p. 1387. The compound represented by the formula () can be easily synthesized by known methods, for example, as disclosed in the U.S. Patent No.
Synthesized by the method described in No. 2661342. Here, R is an aliphatic or aromatic hydrocarbon group with or without a substituent, and R' is a hydrogen atom or an aliphatic or aromatic hydrocarbon group with or without a substituent. Examples include methyl, ethyl, phenyl, biphenyl, P-chlorophenyl, etc. Examples of R' are hydrogen, methyl,
Examples include phenyl and P-tolyl. These can be easily synthesized by known methods, such as those published in ``Journal of the Society of Organic Synthetic Chemistry,'' vol. 28, p. 448 (1970) or ``Industrial and Engineering Chemistry.''
Engineering Chemistry, Vol. 52, p. 412 (1960). When using these compounds, dissolve them in an appropriate solvent, dilute or disperse them in a diluent, and apply them to the interior of the polymerization vessel, the stirrer, the baffle plate, and other parts of the vessel where scale is likely to form or adhere. good. The coating method may be a spraying method, a brushing method, or a dipping method in which the polymerization vessel is filled with a solution or diluted solution of the compound. Solvents or diluents are not particularly limited, but include, for example, pentane, hexane, heptane, octane, cyclohexane, benzene, toluene, chloroform, dichloroethane, trichloroethane, tetrachloroethylene, chlorobenzene, diethyl ether, tetrahydrofuran, methanol, ethanol, propanol. , butanol, ethyl acetate, etc., and these may be used alone or in combination of two or more. The amount of the compound to be applied may be such that a thin film of the compound is formed on the coated surface, but it is usually from 0.001g/ ^m2 to 5.0g/m2.
A range of g/m ² is used. When the amount is less than 0.001 g/m ² , it becomes difficult to completely coat the coated surface with the compound, so scale formation and adhesion may be observed in some areas. Increasing the amount of application generally increases the effect, and the number of batches over which the effect lasts after one application can be increased. Regarding the upper limit of the coating amount, it does not preclude use at 5 g/m ² or more unless there is any particular adverse effect. However, if the amount applied is extremely large, it may be mixed into the product, and the effect may not be increased in proportion to the amount used, which is not necessarily preferable. The present invention is applicable to the polymerization of vinyl chloride alone or a copolymerizable monomer mixture containing vinyl chloride as a main component. The monomers copolymerizable with vinyl chloride mentioned here include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl stearate, vinyl ethers such as methyl vinyl ether, carboxylic acids such as acrylic acid and methacrylic acid, and acrylic acids. Acrylic acid and methacrylic acid esters such as butyl acrylate, methyl methacrylate, hydroxylethyl methacrylate, maleic acid and fumaric acid or their anhydrides or esters, olefins such as ethylene and propylene, vinylidene chloride, odors These include halogenated olefins such as vinyl chloride and vinyl fluoride, and nitrile compounds such as acrylonitrile and methacrylonitrile. In addition, the ratio of vinyl chloride and these copolymerizable monomers is a mixture consisting of 60.0 to 99.9% by weight of vinyl chloride and 40.0 to 0.1% by weight of copolymerizable monomers, with vinyl chloride being the main component. This is desirable. Furthermore, copolymerizable monomers
Two or more types of monomers may be used as long as the amount is in the range of 40.0 to 0.1% by weight. Suspension polymerization, emulsion polymerization, bulk polymerization, and the like are well known as methods for polymerizing vinyl chloride alone or a mixture of the monomers. Suspension polymerization is carried out in an aqueous medium in the presence of a dispersant and an oil-soluble catalyst, and emulsion polymerization is similarly carried out in an aqueous medium in the presence of an emulsifier and a water-soluble catalyst or, if necessary, a reducing agent.
Moreover, bulk polymerization is performed in the presence of an oil-soluble catalyst. Dispersants for suspension polymerization that can be used in the suspension polymerization of the present invention include known ones such as partially saponified polyvinyl acetate, polyacrylic acid, maleic anhydride copolymers, cellulose derivatives, gelatin, etc. Soluble catalysts include organic peroxides such as benzoyl peroxide, lauroyl peroxide, tertiary butyl perisobuterate, diisopropyl peroxydicarbonate, dioctyl peroxydicarbonate, acetylcyclohexylsulfonyl peroxide, and azobisisobutyl peroxide. Examples include azo compounds such as lonitrile and azobisdimethylvaleronitrile. These may be used alone or in combination of two or more. Examples of emulsifiers that can be used in the emulsion polymerization of the present invention include anionic emulsifiers such as sodium alkylbenzene sulfonate, sodium lauryl sulfonate, sodium dioctyl sulfosuccinate, and sodium lauryl sulfate, polyoxyethylene alkyl ether, and polyoxyethylene alkyl allyl. Examples include nonionic emulsifiers such as ether and polyoxyethylene sorbitan fatty acid partial ester. Water-soluble catalysts include ammonium persulfate, potassium persulfate, hydrogen peroxide, etc., in combination with reducing agents such as ferrous sulfate, sodium sulfite, L- or D-ascorbic acid, if necessary. A redox-based catalyst may also be used. Further, as the oil-soluble catalyst used in the bulk polymerization of the present invention, known catalysts such as the organic peroxides and azo compounds exemplified in the case of the suspension polymerization can be used. In the method of polymerizing vinyl chloride alone or a copolymerizable monomer mixture containing vinyl chloride as the main component, under normal conditions, even if only one batch is polymerized, the inner surface of the polymerization vessel, the stirrer, or the Occurrence and adhesion of polymer scale is observed on plates, etc. For example, stainless steel polymerization vessels lose their metallic luster because the walls are covered with a thin layer of polymer. As the number of batches increases, the thickness of the scale layer generated and adhered increases, and a particularly thick scale layer may be formed depending on the location. This not only causes problems such as a decrease in the heat transfer effect of the vessel wall, a decrease in product yield, and the contamination of peeled scales into the product.
Since much labor and time are required to remove the scale, there is a disadvantage that the operating rate of the polymerization vessel is reduced. In the case of the present invention, if a highly effective compound is applied, no scale formation or adhesion will be observed not only after one batch of polymerization, but also over several batches or more if the amount of application is appropriate. The walls of the stainless steel polymerization vessel can maintain a metallic luster.
Therefore, many of the disadvantages mentioned above can be greatly reduced. This technique could also be used to enable continuous polymerization of vinyl chloride. Next, the present invention will be explained in more detail with reference to Examples. [Reference fee 1] No. 1 of Table-1 of Example 1,

Synthesis of [Formula] 3 g of phenylphosphinate dichloride and 0.26 g of sodium azide were placed in an eggplant flask and reacted at 170° C. for 6 hours in a nitrogen atmosphere. The reaction product became a lump, which was dissolved in benzene to separate it from the by-product sodium chloride, and then poured into petroleum ether for reprecipitation. This precipitate was filtered under reduced pressure,
After washing and drying under reduced pressure, 2.8 g of a resinous white solid was obtained. [Reference example 2] No. 2 of Table-1,

Synthesis of [Formula] 5 g of diphenylphosphinic acid chloride and 1.5 g of sodium azide were placed in an eggplant flask and reacted at 200° C. for 6 hours in a nitrogen atmosphere. The reaction mixture became a lump that did not melt even at 200°C. 70 ml of benzene was added to this product, and the mixture was heated and reduced for 3 hours. After refluxing, the mixture was filtered while hot to separate it from sodium azide and sodium chloride. The benzene solution had a yellow color, and crystals began to precipitate when left overnight. After separating the crystals under reduced pressure,
Evaporation of the benzene from the liquid gave a viscous oil, which upon cooling with ice gave 3.2 g of a resinous solid. [Example 3] No. 3 of Table-1,

Synthesis of [Formula] 2.0 g of a commercially available phosphonitrile chloride trimer was reacted at 300° C. for 5 hours under a nitrogen atmosphere to obtain 1.4 g of a rubbery product. This product was insoluble in organic solvents such as acetone, benzene, ether, DMF, and THF. Therefore, this gummy product was suspended in 10 ml of anhydrous benzene and added to it at 26°C.
A solution of CF ₃ CH ₂ ONa in anhydrous ether was added dropwise with stirring over a period of 20 minutes. Although the reaction solution became cloudy and generated heat, the reaction was continued at 60° C. for 28 hours. After neutralizing with hydrochloric acid, separate the precipitate and wash with methanol,
After drying, 1.0 g of resinous solid was obtained. [Reference example 4] No.6 of Table-1,

Synthesis of [Formula] 70% aqueous solution of ethylamine in an eggplant-shaped flask
1.32g was added and diluted with 10g of benzene. to this
2.0 g of phenylphosmanate dichloride was slowly added dropwise at room temperature. After completion of the dropwise addition, the mixture was allowed to react at room temperature for 3 hours. After removing benzene with an evaporator, the mixture was heated at 180°C for 14 hours to obtain a resinous solid. [Reference example 5] No. 7 of Table-1,

[Example 1]

Compounds shown in Table 1 were dissolved, diluted, or dispersed in a solvent such as tetrahydrofuran, benzene, or ethanol, and then applied to the inner surface of a stainless steel polymerization vessel with a capacity of 1000. After drying the solvent, add 200 kg of vinyl chloride monomer and pure water to this polymerization vessel.
450Kg, add 180g of partially saponified polyvinyl acetate and 50g of azobismethylvaleronitrile, and heat at 56℃.
Polymerization was carried out for 13 to 15 hours. After polymerization is complete,
When the polymer was taken out and the scale attached to the inner surface of the polymerization vessel was weighed, the results shown in Table 1 were obtained.

【table】 In the above coating compound

[Formula] and Beauty

[Comparative example 1]

Vinyl chloride was polymerized under the same conditions as in Example 1, except that an epoxy resin (Epicote 828) was dissolved in acetone and the coating amount was 0.05 g/m ² . After polymerization,
When the amount of scale adhering to the inner surface of the polymerization vessel was weighed, it was 310 g/m ² , which was greater than the amount of adhesion of 225 g/m ² when no coating was applied. [Example 2] The compounds shown in Table 2 were dissolved and dispersed in tetrahydrofuran, ethanol, etc. and applied to the inner surface of a stainless steel polymerization vessel having a volume of 1000. Polymerization was carried out in the same manner as in Example 1, and the polymerization was repeated three times without cleaning the inside of the polymerization vessel. An attempt was made to weigh the amount of scale after three batches of polymerization, but there was no scale on the inner walls of the polymerization vessel or on the attached equipment, and it had a metallic luster. On the other hand, when these compounds were not applied, 225 g/m ² of scale was generated and adhered even after one batch polymerization.

[Example 3]

On the inner surface of a stainless steel polymerization vessel with a capacity of 1000,

[Example 4]

On the inner surface of a stainless steel polymerization vessel with a capacity of 1000,

[Example 5]

Preliminarily coat the inner surface of a stainless steel polymerization vessel with a capacity of 2.

A 10% ethanol solution of [Formula] was applied. Remove ethanol under reduced pressure, 1240
g/m ² of this polymer was attached to the inner surface of the polymerization vessel, stirring blades, etc. After purging the polymerization vessel with nitrogen, a benzene solution containing 700 g of vinyl chloride monomer and 0.4 g of azobisdimethylvaleronitrile was charged, and polymerization was carried out at 56°C for 7 hours. Next, I took out the contents and measured the amount of scale attached to the inside of the container, and found that it was 42g/
It was ^m2 . On the other hand, when the above polymerization was carried out without coating anything, a scale of 520 g/m ² was observed.

Claims (1)

[Scope of Claims] 1. When polymerizing vinyl chloride alone or a copolymerizable monomer mixture containing vinyl chloride as the main component, the following formula () to each part of the polymerization vessel, such as the inner surface and stirring blades, may be used. A method for polymerizing vinyl chloride, which comprises applying in advance a polymer shown in parentheses whose main chain consists of phosphorus atoms and nitrogen atoms. [Here, R and R′ are halogen groups, or aliphatic or aromatic hydrocarbon groups with or without substituents] [Here, R and R′ are aliphatic or aromatic hydrocarbon groups with or without substituents] [Here, R is an aliphatic or aromatic hydrocarbon group with or without a substituent, and R' is a hydrogen atom or an aliphatic or aromatic hydrocarbon group with or without a substituent.] 2 Coating the polymer 2. The method of claim 1, wherein the amount is in the range 0.001 to 5 g/m ^<2> . 3. The method of claim 1, wherein the polymer is applied by spraying, brushing or dipping. 4. The copolymerizable monomer mixture containing vinyl chloride as a main component is 60.0 to 99.9% by weight of vinyl chloride.
The method of claim 1 comprising 40.0-0.1% by weight of copolymerizable monomer. 5. The method of claim 3, wherein the polymer is dissolved in a solvent or diluted or dispersed in a diluent and applied.