JPS6028287B2 - Suspension polymerization method for vinyl compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to the suspension polymerization of vinyl compounds, particularly vinyl chloride.

When producing vinyl chloride resins industrially, a suspension polymerization method is widely used in which vinyl chloride monomers are dispersed in an aqueous medium in the presence of a suspension stabilizer and polymerized using an oil-soluble catalyst. There is.

In general, the factors that control the quality of the resin include the polymerization rate, water-monomer ratio, polymerization temperature, amount of catalyst, and type and amount of dispersion stabilizer, among which the dispersion stabilizer is said to have the greatest influence. ing. The performance required of a dispersion stabilizer for vinyl chloride polymerization is: ■ It must exhibit sufficient dispersion power when used in a small amount, and it must have the ability to sharpen the particle size distribution of the resulting vinyl chloride polymer particles. ■ Polymer In order to increase the plasticizer absorption rate of the particles and facilitate molding processability, it is possible to make the particles porous with a high porosity.

As such a dispersion stabilizer, polyvinyl alcohol corresponding to component {B) of the present invention, that is, a saponification degree of 60 to 90 mol%
Partially saponified polyvinyl alcohol has been widely used and is known as a dispersion stabilizer with excellent performance.

However, such partially saponified polyvinyl alcohol has a problem because it lacks the above-mentioned performance (1), and although it usually achieves a satisfactory effect in (2), it requires a particularly strict sharpness of the particle size distribution. For example, when polyvinyl chloride resin is used for powder coating, etc., it may not always be satisfactory, and if such performance is improved, the field of application of polyvinyl alcohol will be further expanded, which is extremely advantageous industrially. be.

However, as a result of extensive research in order to solve this problem, the present inventor has introduced less than 0.3 mol% of wind sulfonic acid groups as a suspension stabilizer during suspension polymerization of vinyl chloride in an aqueous medium. The modified vinyl acetate copolymer preferably has
And [B - degree of saponification 60 to 90 mol%, degree of polymerization 100
The present invention was completed based on the discovery that when using polyvinyl alcohol with a polyvinyl alcohol of 3000 to 3,000, the porosity of the resulting vinyl chloride resin particles is improved and the particle size distribution of the particles becomes even sharper, which is a remarkable effect. I ended up doing it.

The 'B' suspension stabilizers used in the present invention, particularly those in the high saponification degree range, are of well-known varieties, but the drawback of the polyvinyl alcohol suspension stabilizers is that The improvement achieved by using a sulfonic acid group-containing modified vinyl acetate copolymer as a stabilizer is a novel fact that could not have been predicted based on previous knowledge. This will be explained in detail below. First, the Tsukuda suspension stabilizer used in the present invention must be polyvinyl alcohol with a degree of saponification of 60 to 90 mol % and a degree of polymerization of 100 to 3,000.

If the degree of saponification is less than 60 mol%, the protective colloid properties will decrease and the particle size distribution of the pinyl chloride polymer particles will become broad, while if it is more than 90 mol%, the surface activity will decrease and the porosity of the particles will decrease. There are drawbacks. Furthermore, if the degree of polymerization is less than 100, a product with a large polymer particle size is likely to be obtained, which poses a practical problem, while if it is more than 3,000, the particle size distribution becomes broad. Next, in the modified vinyl acetate copolymer into which wind sulfonic acid groups are introduced, which is used in the present invention, the content of sulfonic acid groups must be limited to 0.3 mol %. Outside this range, it is difficult to obtain polyvinyl chloride with a large porosity and a sharp particle size distribution. The sulfonic acid group may be in the free acid form or as a sodium salt,
It may be in the form of potassium salt, ammonium salt, etc. Furthermore, the modified vinyl acetate copolymer may be a partially saponified product in which a portion of the vinyl acetate moiety is substituted with a hydroxyl group. The degree of saponification of the partially saponified product is desirably 90 mol% or less in terms of surfactant power and protective colloid power, and particularly preferably 30 mol% or less.
A range of 90 mole % is useful. In addition to the sulfonic acid group, the copolymer may contain other copolymerizable monomers, such as higher alkyl vinyl ethers, higher fatty acid vinyl esters, long chain Q-olefins, and non-sulfonic acid groups, to the extent that the effects of the present invention are not impaired. It is also possible to polymerize hydrophobic monomers such as saturated carboxylic acid long-chain alkyl esters and hydrophilic monomers such as unsaturated carboxylic acids and their salts or amides. Such a modified vinyl acetate copolymer into which sulfonic acid groups have been introduced can be produced by any method. Here are some examples: (1) A method in which an olefin sulfonic acid such as ethylene sulfonic acid, allyl sulfonic acid, meta-allylsulfonic acid, or a salt thereof and vinyl acetate are polymerized in an alcohol or an alcohol/water temperature solvent.

Or a method of further saponifying the polymer. @ A method of copolymerizing a sulfoalkyl maleate represented by the general formula or [R is an alkyl group, n is an integer of 2 to 4, M is hydrogen or an alkali metal ammonium ion] and vinyl acetate, or further saponification thereof how to.

Examples of the above-mentioned sulfoalkyl malates include sodium sulfopropyl 2-ethylhexyl maleate, sodium sulfopropyl tridecyl maleate, and sodium sulfopropyleicosyl maleate. (2) A method of copolymerizing sulfoalkyl (meth)acrylamide represented by the general formula or [R is Mizumasa or a methyl group, R2 is hydrogen or an alkyl group, n and M are the same as @] and vinyl acetate.

How to further saponify this. Furthermore, a method of copolymerizing a sulfoalkyl (meth)acrylate represented by the general formula and vinyl acetate, and a method of saponifying the same.

@ A method in which polyvinyl alcohol is treated with bromine, iodine, etc. and then heated in an acidic sodium sulfite aqueous solution.

■ A method in which polyvinyl alcohol is heated in a concentrated aqueous sulfuric acid solution.

6. A method of acetalizing polyvinyl alcohol with an aldehyde compound having a sulfonic acid group.

etc. The above-mentioned wind sulfonic acid group-introduced vinyl acetate copolymer and 'B) degree of saponification 60 to 90 mol%, degree of polymerization 100 to
Among the combinations with polyvinyl alcohol of 3000, it is a modified vinyl acetate copolymer with a sulfonic acid group content of less than 0.3 mol%, and whose degree of saponification is 30 to 30%.
90 mol% partially saponified product and [B} as saponification degree 60
The combined use with polyvinyl alcohol having a polymerization degree of 300 to 3000 at a concentration of 90 mol % is particularly desirable from the viewpoint of surface active ability and protective colloid power.

In the case of using the combination of {B} and {B}, the following methods are available in addition to mixing {circle around (2)} and 'B} as described above. A method in which vinyl acetate is homopolymerized, then a sulfonic acid group-containing monomer is added, the copolymerization is continued, and the obtained polymer polymer is saponified, and a method in which vinyl acetate and a sulfonic acid group-containing monomer are homopolymerized A method of copolymerizing and then saponifying the polymer obtained by adding vinyl acetate and homopolymerizing, a method of using a reaction mixture in which polyvinyl alcohol is partially sulfonated, etc. Any method can be used. When using suspension stabilizers together, the mixing amount should be
{B}=9/1~0.1/9. My nephew is 7/3~0
．． It is necessary to select 5/9.5. Suspension polymerization is usually carried out in the presence of an oil-soluble catalyst by adding a suspension stabilizer to water and dispersing the vinyl chloride monomer.

Suspension stabilizers can be added to the aqueous medium as a powder or in the form of a solution. When added in the form of a solution, it is added as an aqueous solution, or as a solution dissolved in an organic solvent such as alcohol, ketone, ester, or a mixed solvent with water. The suspension stabilizer of the present invention is used in an amount of 0.01 to 1% by weight, preferably 0.02 to 0.5% by weight, based on the vinyl chloride monomer.

(2), 'B', and other types of suspension stabilizers having different amounts of modification, degrees of saponification, and degrees of polymerization can be used in combination as long as the scope of the present application is satisfied. Furthermore ■,
Both dispersion stabilizers 'B} may be charged all at once at the beginning of the polymerization, or may be charged in portions during the polymerization. The catalyst used may be any oil-soluble catalyst, such as penzoyl/gu oxide, lauroyl/gu oxide, diisopropyl peroxydicarbonate, Q.
Q'-azopisisobutyronitrile, Q.Q'-azobis-2.4-dimethylvaleronitrile, acetylcyclohexylsulfonyl/g-oxide or mixtures thereof are used. The polymerization temperature is selected from a range of about 30-70°C. It is also possible to appropriately use various surfactants, protective colloids, inorganic dispersants, etc. as auxiliaries during polymerization. Furthermore, in the present invention, not only vinyl chloride is homopolymerized, but also copolymerized with a monomer copolymerizable with vinyl chloride.

C as a copolymerizable monomer. Vinylidene genide,
Examples include vinyl ether, vinyl acetate, vinyl benzoate, acrylic acid, methacrylic acid and its ester, maleic acid or its anhydride, styrene, and the like. Although the polymerization of vinyl chloride has been mainly described above, the method of the present invention is not necessarily limited to the case of vinyl chloride, but can be applied to the suspension polymerization of any vinyl compound such as styrene or methacrylate.

Next, the method of the present invention will be explained in more detail by giving examples.

Examples 1 to 10, Control Example 1 Capacity 100 equipped with rope companion machine
Into the stainless steel autoclave were placed 15 parts of deionized water, 10 parts of vinyl chloride monomer, a predetermined amount of a suspension stabilizer as shown in Table 1, and 0.0 parts of lauryl peroxide.
Two parts were charged and suspension polymerization was carried out at 60 pm.

Table 1 shows the performance of the vinyl chloride polymer obtained. No.
1 Table (Note) Porosity measurements are with mercury.

Claims (1)

[Claims] 1 When suspension polymerizing a vinyl compound in an aqueous medium, as a suspension stabilizer (A) a modified vinyl acetate copolymer into which less than 0.3 mol% of sulfonic acid groups have been introduced, or (B) saponification thereof. A method for suspension polymerization of vinyl compounds, characterized in that partially saponified polyvinyl alcohol having a degree of polymerization of 60 to 90 mol % and a degree of polymerization of 300 to 3,000 is used.