JPH0660211B2 - Polymerization method of vinyl monomer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improved method for polymerizing vinyl monomers, and more specifically, suspension of vinyl monomers using an aqueous medium. The present invention relates to a polymerization method for preventing adhesion of polymer scale generated on the inner surface of a polymerization reactor during polymerization or emulsion polymerization.

[Conventional technology]

When polymerizing a vinyl monomer in the presence of a dispersant or emulsifier and a polymerization initiator, a problem that a solid polymer called scale adheres to the inner surface of the polymerization reactor, that is, its inner wall, stirring blades, baffle plates, condensers, etc. There is.

Due to this scale, heat transfer efficiency is reduced, product yield is reduced, quality is deteriorated due to inclusion of peeling scale into products, productivity is reduced due to the time and labor required for scale removal, and occupational health and safety. The above problems cause many disadvantages.

To solve these problems, many methods have been proposed to prevent scale formation and its adhesion to the polymerizer.

For example, dyes, pigments, other polar organic compounds, inorganic acids and their salts, polyvalent metal salts, etc. may be applied to the inner surface of the polymerization vessel or added to an aqueous medium. However, there are drawbacks such as poor sustainability and deterioration of various product characteristics. As a method for improving these, a method of applying a polymer compound having a functional group that prevents scale formation to the inner surface of the polymerization vessel has been proposed.

BACKGROUND ART Conventionally, phenol compounds have been used as polymerization inhibitors, and many methods using them have been proposed.

For example, JP-A-55-16004 discloses a reaction product of a phenol-aldehyde initial condensation product with nitrophenols, and US Pat. No. 4,080,173 discloses self-condensed polyphenols and polyhydric compounds. Naphthol, a condensate of a phenolic compound and an aromatic aldehyde in JP-A-55-54317, JP-A-55-102610.
In the publication, propylene glycol alginate,
Japanese Patent Application Laid-Open No. 55-11209 discloses a nitrile-containing polymer, and Japanese Patent Application Laid-Open No. 58-204006 discloses a reaction product of a drying oil or a semi-drying oil with a phenol compound and, if necessary, an aldehyde. A method of doing so is disclosed.

However, when these methods are used, there are many points to be improved, for example, the polymerization rate is lowered, and the durability of the coating film is insufficient, which causes a problem in the sustainability of the descaling effect.

[Problems to be solved by the invention]

As a result of intensive research to eliminate these drawbacks, the present inventors have found that a certain polymer compound, particularly during the polymerization of vinyl monomers, is applied to the inner surface of the polymerization vessel to carry out the polymerization. The inventors have completed the present invention by discovering that scale adhesion can be greatly prevented.

[Means for solving problems]

That is, the present invention is characterized in that, when polymerizing a vinyl monomer in an aqueous medium, a reaction product of a high molecular halogen compound and a phenolic compound is applied to the inner surface of the polymerization vessel in advance. The present invention relates to a method for polymerizing a monomer.

Examples of the polymer halogen compound used in the present invention include polychloromethylstyrene, a copolymer of styrene and chloromethylstyrene, a chloromethylated product of polystyrene, or polyepichlorohydrin, a copolymer of epichlorohydrin and ethylene oxide, and epichlorohydrin. Tertiary copolymers with ethylene oxide and allyl glycidyl ether, poly-3,3-bis (chloromethyl) oxetane, polychloromethyl acrylate,
Examples thereof include high molecular weight chloroalkyl compounds such as polychloroethyl acrylate and polyvinyl chloroethyl ether, and halogenated polystyrene such as chlorinated polystyrene, brominated polystyrene and lithiated polystyrene.

As the phenolic compound, phenol and divalent phenolic compounds such as resorcin, catechol, hydroquinone and bisphenol A, or trivalent phenolic compounds such as pyrogallol, hydroxyhydroquinone and phloroglucin, and alkyls of the above compounds Examples thereof include compounds having a substituent such as a group and a carboxylic acid group.

As a method for producing a reaction product of a polymeric halogen compound and a phenolic compound of the present invention, a polymeric halogen compound and a phenolic compound are used in a molecule with a Friedel-Crafts catalyst in a suitable solvent. And a reaction method using a phenoxide prepared from the above phenolic compound and sodium hydroxide or potassium hydroxide.

As the Friedel-Crafts catalyst, for example, a metal halide such as aluminum chloride, zinc chloride, tin chloride, iron chloride or boron trifluoride is used. These reactions are 1
0 to 200 ° C, preferably 40 to 150 ° C, 5 minutes to 10
The time is preferably 1 to 5 hours.

The mixing ratio of the high molecular halogen compound and the phenolic compound is 1 mol of the halogen group and 1 mol of each of the halogen group and the unsaturated group when the unsaturated group is contained in the molecule.
The phenolic compound is used in an amount of 0.5 to 5 mol, preferably 0.8 to 2 mol, per mol.

As the solvent used in the reaction system, an inert solvent such as acetone, dioxane, methyl ethyl ketone, and methyl isobutyl ketone is suitable when the Friedel-Crafts catalyst is used, and when phenoxide is used, the solvent other than these solvents is suitable. Ether, tetrahydrofuran, dimethyl sulfoxide, water, etc. are used for the above, but in either case, it is possible to react in the absence of solvent.

The amount of the Friedel-Crafts catalyst is 0.001 to 10 parts, preferably 0.1 to 2 parts, based on 100 parts of the mixture of the high molecular halogen compound and the phenolic compound, and the phenoxide is used. It is prepared with a phenolic compound and equimolar potassium hydroxide or sodium hydroxide.

The descaling agent thus produced is used by dissolving it in a hydrocarbon-based polar solvent or an alkaline solution.

The solution spray method so that the proportion of 0.01g / m ² ~10g / m ² as a descaling agent per square meter of the polymerization vessel surfaces of interest, deposited on methods polymerization vessel surface, such as rinsing method To use.

The polymerization of the vinyl-based monomer using the present invention includes suspension polymerization,
Emulsion polymerization is adopted, but the dispersant, emulsifier, initiator and the like used in this polymerization are not particularly limited and commonly used ones can be used.

For example, as the dispersant and the emulsifier, a partially saponified product of polyvinyl acetate, an acrylic acid copolymer, a cellulose derivative, gelatin, a protective colloidal compound such as starch, or an ester of a higher fatty acid and a polyhydric alcohol,
Anionic surfactant such as polyoxyethylene derivative,
Anionic surfactants such as metal salts of higher fatty acids and metal salts of alkylbenzene sulfonic acids are used.

Examples of the polymerization initiator include organic peroxides such as benzoyl peroxide, lauroyl peroxide and dioctyl peroxydicarbonate, azo compounds such as azobisisodimethylvaleronitrile, and persulfates such as potassium persulfate and ammonium persulfate. used.

The vinyl-based monomer referred to here is a monomer having a vinyl group, for example, olefins such as ethylene and propylene, vinyl halides such as vinyl chloride and vinylidene chloride, vinyl esters such as vinyl acetate, Vinyl ethers such as ethyl vinyl ether, acrylic acid esters such as methyl methacrylate, metal salts or esters such as maleic acid and fumaric acid, aromatic vinyls such as styrene, and diene-based monoamines such as butadiene, chloroprene and isoprene And vinyl monomers that are copolymerizable with these monomers.

The polymerization temperature is usually in the range of 30 to 80 ° C.

INDUSTRIAL APPLICABILITY The present invention can be used for the polymerization of the above vinyl-based monomers alone or a mixture of two or more vinyl-based monomers, and particularly shows a remarkable effect on the polymerization of vinyl chloride-based monomers. .

〔The invention's effect〕

As described above, scale adhesion can be significantly improved.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to Examples.
This does not limit the scope of the invention.

[Reference Example 1] A four-necked flask equipped with a stirrer, a thermometer and a reflux condenser had a molecular weight of 6000 and a chloromethylation degree of 5
100 parts of 0 mol% chloromethylated polystyrene, 80 parts of pyrogallol, and 400 parts of dioxane were charged, stirred and completely dissolved, and then heated to 100 ° C.,
2 parts of aluminum chloride was gradually added thereto, and the reaction was carried out for about 1 hour and 30 minutes.

After completion of the reaction, the reaction product was thoroughly washed with water and dried.

Reference Example 2 As in Reference Example 1, pyrogallol 270 was placed in a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser.
And 120 parts of potassium hydroxide were dissolved in 350 parts of methyl ethyl ketone at 80 ° C.

There, the specific gravity is 1.38 and the Mooney viscosity is 60 ± 1 in advance.
A solution of 100 parts of 0 mL1 + 4 (100 ° C.) polyepichlorohydrin dissolved in 250 parts of methyl ethyl ketone was added dropwise and reacted at 80 ° C. for 4 hours.

Then, the product was washed with water and dried in the same manner as in Reference Example 1.

Comparative Example 1 After charging 250 parts of pure water, 0.25 part of partially saponified polyvinyl acetate and 0.05 part of 2,2′-azobis-2,4 dimethylvaleronitrile into a polymerization vessel having an internal volume of 1 m ³ . Then, 100 parts of vinyl chloride monomer was injected under reduced pressure.

Then, the mixture was heated to 57 ° C. with stirring, and when the pressure in the polymerization reactor dropped 2 kg / cm ² from the pressure in the steady state of the polymerization reaction, the recovery of unreacted monomers was started.

The polymerization time at this time was 10 hours.

Then, after recovering the unreacted monomer, the polymerization suspension was taken out from the polymerization vessel, and the inner surface was washed with low pressure water. Then, when the amount of scale adhered to the inner surface of the polymerization vessel was measured, it was 150
It was g / m ² .

[Examples 1 and 2] The products obtained by the methods of Reference Examples 1 and 2 were each added to 5
% Ethanol solution was spray-coated on the inner surface of the polymerization vessel used in Comparative Example 1 and dried.

The coating amount at this time was 0.5 g / m ² .

Using this polymerization vessel, a polymerization reaction was carried out in the same manner as in Comparative Example 1. As a result, the polymerization time was 10 hours, and the scale deposits were 4 g / m ² and 5 g, respectively.
Was / m ² .

Comparative Example 2 250 parts of pure water and 5 parts of vinyl acetate were placed in a polymerization vessel having an internal volume of 1 m ^3.
Parts, partially saponified polyvinyl acetate 0.25 parts, 2,2'-
After charging 0.05 part of azobis-2,4 dimethylvaleronitrile, 100 parts of vinyl chloride monomer was injected under reduced pressure, and then the mixture was heated to 60 ° C. with stirring, and the pressure in the polymerization vessel was adjusted to 60 ° C. 2 kg / cm from the pressure in the steady state of the polymerization reaction
^{When the} temperature dropped to ² , the recovery of unreacted monomer was started.

The polymerization time at this time was 8.5 hours.

Then, after recovering the unreacted monomer, the polymerization suspension was taken out from the polymerization vessel, and the inner surface was washed with water.

Then, the amount of scale attached to the inner surface of the polymerization vessel was measured and found to be 195 g / m ² .

[Examples 3 and 4] The products obtained by the methods of Reference Examples 1 and 2 were each added to 5
% Ethanol solution, and spray-coated on the inner surface of the polymerization vessel used in Comparative Example 2 and dried.

The coating amount at this time was 0.5 g / m ³ .

Using this polymerization vessel, a polymerization reaction was carried out in the same manner as in Comparative Example 2. As a result, the polymerization time was 8.5 hours and the scale adhesion amount was approximately 8 g / m ² .

Claims (5)

[Claims] 1. When polymerizing a vinyl monomer in an aqueous medium, a reaction product of a high molecular halogen compound and a phenolic compound is applied on the inner surface of a polymerization vessel in advance. Polymerization of monomers. 2. The vinyl monomer is vinyl chloride alone, or
The polymerization method according to claim 1, which is a mixture of vinyl chloride and a monomer copolymerizable therewith. 3. The polymerization method according to claim 1, wherein the high molecular halogen compound is a high molecular chloroalkyl compound. 4. The phenolic compound is phenol and a divalent phenolic compound such as resorcinol, catechol, hydroquinone and bisphenol A, or a trivalent phenolic compound such as pyrogallol, hydroxyhydroquinone and phloroglucin. The method of polymerization according to item 1. 5. The polymerization method according to claim 3, wherein the high molecular weight chloroalkyl compound is chloromethylated polystyrene and polyepichlorohydrin.