JPH03290404A - Dispersion stabilizer for suspension polymerization of vinylic compound - Google Patents

Abstract

PURPOSE:To provide dispersion stabilizer capable of giving vinyl chloride-based resin granules with sharp granular size distribution and excellent in porosity and uniformity, consisting of a vinyl alcohol-based polymer having 2-pyrrolidone ring-contg. copolymerizable unit with the saponification degree falling within a specified range. CONSTITUTION:The objective dispersion stabilizer consisting of vinyl alcohol- based polymer (pref. a saponified product of a vinyl acetate-based polymer) containing 0.1-25 (pref. 5-20)mol% of 2-pyrrolidone ring-contg. copolymerizable unit [pref. containing group of the formula (R1-R6 are each H or alkyl)] and 50-95 (pref. 65-85)mol% in saponification degree.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention A is a monomer mixture containing a vinyl compound, particularly vinyl chloride, or another monomer that can be copolymerized with vinyl chloride (hereinafter collectively referred to as vinyl chloride yarn material). This invention relates to a dispersion stabilizer used in suspension polymerization in an aqueous medium.

When producing vinyl chloride resin industrially, a measured polymerization method is used in which vinyl chloride monomers are dispersed in an aqueous medium in the presence of a dispersion stabilizer and polymerized using an oil-soluble catalyst. Wide
It has been implemented. In general, factors that control the quality of the resin include the polymerization rate, water-monomer ratio, polymerization temperature, type and amount of catalyst, type of polymerization tank, stirring speed, and type and amount of dispersion stabilizer. But especially the dispersion stabilizer! I know that the influence of the order is very large.

The properties required for a separation stabilizer for suspension polymerization of vinyl chloride threads are (i) a high dispersion force when used in a small amount, and a particle size distribution of the vinyl chloride polymer particles that can be obtained; (ii) to increase the absorption rate of the plasticizer to facilitate processability and to facilitate the removal of vinyl chloride monomer remaining in the polymer particles; It has the function of making each polymer particle as uniform as possible and porous in order to prevent the formation of fisheye etc. in the product, (iii) It has the function of creating polymer particles with a high filling specific gravity, and (iv) Polymerization Remove scale adhesion to tanks, etc. 1. (V) The obtained polymer particles have high thermal stability.

Conventionally, cellulose derivatives such as methylcellulose and carboxymethylcellulose, partially saponified polyvinyl alcohol, and the like have been used alone or in combination as dispersion stabilizers for suspension polymerization of vinyl compounds. However, these methods have drawbacks such as low ability to make vinyl chloride polymer particles porous, slow plasticizer absorption rate, and difficulty in removing residual vinyl chloride monomers.

In order to improve these drawbacks, a dispersion stabilizer for real-temperature polymerization having, for example, an N,N-dimethylacrylamide unit or, for example, an N-methylolacrylamide unit as a copolymerization unit, has been disclosed (Japanese Unexamined Patent Application Publication No. 1983-1989). 240
No. 701 and JP-A No. 60-240702 wA) 0
However, these dispersion stabilizers do not meet the above (i) to (iii)
Although the performance was satisfactory, there were drawbacks such as scale adhesion to the polymerization tank and thermal stability of the polymer particles.

Problems to be Solved by C6 The object of the present invention is to provide a dispersion stabilizer for suspension polymerization of vinyl compounds that does not have any of the above-mentioned problems (i) to (v) 2) and 4.

In order to solve the problem 01, the present inventors have overcome such drawbacks and achieved the above-mentioned (i) to (
As a result of intensive research to develop a dispersion stabilizer that simultaneously satisfies the required performance of V), surprisingly, a dispersion stabilizer containing 0.1 to 25 mol% of copolymerized units containing a 2-pyrrolidone ring,
When using a dispersion stabilizer for suspension polymerization of vinyl alcohol compounds having a saponification degree of 50 to 95 mol%, almost the same particle size distribution can be obtained with good reproducibility.
The particle size distribution is sharp, each particle is porous, and the uniformity is quick to tl. Moreover, the filling specific gravity is large, there is no scale adhesion to the polymerization tank, etc., and polymer particles with good thermal stability can be obtained. However, the present invention has been completed by discovering that all of the above-mentioned performances (i) to (v) are satisfied.

The 2-pyrrolidone ring contained as a copolymerized unit in the vinyl alcohol polymer of the present invention includes those in which the hydrogen atom of 2-pyrrolidone is substituted with other substituents, but among them, the general formula (r However, R1-R6 represent a hydrogen atom or an alkyl group, respectively.
Most preferably, one or all hydrogen atoms are hydrogen atoms.

The content of copolymerized units containing 2-pyrrolidone rings in the vinyl alcohol polymer is preferably in the range of 01 to 25 mol%, more preferably in the range of 5 to 20 mol%. If the content of the copolymerization unit is less than 0.1 mol %, the packing specific gravity, which emphasizes vinyl chloride, will decrease, and if it exceeds 25 mol %, scale will increase in the polymerization tank, which is not preferable.

The degree of saponification of the vinyl alcohol polymer is preferably from 50 to 95 mol%, more preferably from 65 to 85 mol%. If the saponification degree is less than 50 mol%, the polymerization of the vinyl compound is considered unstable, and the saponification degree is 95 mol%.
If it exceeds this value, the porosity of the vinyl chloride resin will decrease, which is not preferable.

Although there are no particular restrictions on the electrical sonicity of the vinyl ester polymer, it is preferably 100 or more, and more preferably 500.
The above is good.

Ka Ks The vinyl alcohol polymer of the present invention has the following 2-
It can be obtained by copolymerization of a monomer containing a pyrrolidone ring and a vinyl ester monomer, and further by partial saponification. 2-B mentioned above. Regarding monomers containing a lydone ring and having a polymerizable double bond, groups such as vinyl, allyl, styryl, acryloxy, methacryloxy, vinyl ether, and allyl ether can be used as the double bond portion. Of these, vinyl groups and allyl groups are preferred from the viewpoint of copolymerizability with fatty acid vinyl and alkali resistance during saponification. Specific examples of such monomers include N-vinyl-2-pyrrolidone, N-vinyl-2-pyrrolidone,
Examples include 5-methyl-2-pyrrolidone, N-vinyl-5,5-dimethyl-2-pyrrolidone, and N-allyl-2-pyrrolidone.

Among these, N-vinyl-2-pyrrolidone is the most preferred monomer. Further, specific examples of fatty acid vinyl include vinyl formate, vinyl acetate, vinyl butyrate, vinyl pivalate, vinyl persate, etc. Among these, vinyl acetate is the industrially most preferred monomer.

For the copolymerization, conventionally known bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, etc. are used, but solution polymerization using methanol as a solvent is industrially most suitable.

Various conventionally known saponification methods can be applied to the saponification reaction, but among these, the method of alcoholysis using an alkali hydroxide in methanol is simple and preferred. The vinyl alcohol polymer may also contain a small amount of a third component. The third component may contain ionic groups such as anions and cations, or may contain nonionic groups other than the 2-pyrrolidone ring.

Although the dispersion stabilizer of the present invention can sufficiently exhibit its effects by itself, conventionally known dispersion stabilizers or dispersion aids can be used in combination as long as this effect is not impaired.

Examples include cellulose derivatives such as methylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and carboxylmethylcellulose, gelatin, and water-soluble polymers such as polyvinyl alcohol. Polymerization degree is 1 for polyvinyl alcohol
Conventionally known polyvinyl alcohol with a saponification degree of 00 to 3000 and a saponification degree of 60 to 90 mol% or a polymerization degree of 100 to 3
000 and a conventionally known polyvinyl alcohol having a degree of saponification of 20 to 60 mol%. These polyvinyl alcohols may contain ionic groups such as cations and anions in their side chains, or nonionic groups other than the 2-pyrrolidone ring.

When using the vinyl alcohol polymer of the present invention as a dispersion stabilizer to carry out suspension polymerization of vinyl chloride alone or a mixture of vinyl chloride as a main component and a monomer copolymerizable with vinyl chloride,
Usually, a dispersion stabilizer is added to an aqueous medium, a vinyl chloride monomer or a mixture of a monomer copolymerizable with the vinyl chloride monomer is dispersed, and an oil-soluble catalyst is added to the mixture. The dispersion stabilizer can be added to the aqueous medium as a powder or as an aqueous solution.

The dispersion stabilizer is a vinyl chloride monomer or a mixture of vinyl chloride monomer and a monomer that can be copolymerized with Shimo R3.
It is used in a proportion of 0.005 to 1% by weight, preferably 0.01 to 0.05% by weight.

The catalyst used in the real-temperature polymerization may be any oil-soluble catalyst, such as benzoyl peroxide, lauroyl peroxide, diisopropyl peroxydicarbonate), 2.2°-azoisobutyro Nitrile, 2,2°-azobis-2,4-dimethylvaleronitrile or mixtures thereof are used.

The electric sound temperature is selected from a range of about 30 to 100°C.

One or more nonionic surfactants and/or anionic surfactants can also be used in combination during polymerization.

Although the above description has mainly focused on the polymerization of vinyl chloride, the dispersion stabilizer of the present invention is not necessarily limited to the polymerization of vinyl chloride, and includes vinylidene chloride, alkyl vinyl ether, vinyl acetate, acrylic acid and its esters, methane, etc. Contains one or more components from the group consisting of acrylic acid and its esters, maleic acid and its anhydride, itaconic acid, styrene, vinyl chloride, acrylonitrile, isoprene, isobutyne, α-olefins such as butadiene, and ethylene. It is also used for suspension polymerization of vinyl compounds.

LjL Gloss Color The present invention will be explained in more detail with reference to Examples below, but the dispersion stabilizer of the present invention is not limited to these Examples. In the examples, parts indicate parts by weight.

Examples 1 to 8, Comparative Examples 1 to 6 In a 10Q1 glass-lined autoclave, 150 parts of deionized water, various dispersion stabilizers shown in Table 1, and G-2 were added.
After charging 0.2 parts of (ethylhexyl oxydicarbonate) and removing oxygen by degassing the inside of the autoclave to 50a Hg, 100 parts of vinyl chloride monomer was charged, and the autoclave was stirred at a rotation speed of 600 rpm. Polymerization was carried out by raising the temperature to 57°C.

At the start of polymerization, the pressure inside the autoclave was 11. OKG
/ C garden, G was warm, 4.0 kg 7 hours after polymerization started
/cm'G, the polymerization was stopped at this point, unreacted vinyl chloride monomer was purged, and the contents were taken out, dehydrated, and dried.

The polymerization yield of vinyl chloride resin is 85%, and the average degree of polymerization is 1.
It was 100.

The measurement results of the physical properties of the obtained vinyl chloride resin are shown in Table 2.
″″“・ p, i, 7
Margin 1) 2) 3) 4) Particle size distribution, measured by dry sieving using a wire mesh based on Tyler Metsutsuyu standards.

Filling specific gravity: Measured according to JIS K6721-1959.

Uniformity of particle porosity: A mixture of 100 parts of vinyl chloride resin, 50 parts of dioctyl phthalate, 1 part of dibutyltin maleate, 1 part of cetyl alcohol, 0.25 parts of titanium white, and 0.1 part of carbon black was rolled on a roll at 150°C. The mixture was kneaded for a predetermined period of time to form a sheet with a wall thickness of 0.2 ms, and light was transmitted through the sheet to count the number of fish eyes contained in the sheet per 100 c. This shows that the faster the fish eyes disappear, the more uniform the particle porosity is.

Using a planetary mixer connected to a plasticizer absorbent niblastograph, 100 parts of vinyl chloride resin and 50 parts of dioctyl phthalate were placed in a container kept at 80°C.
After stirring, the kneading torque for each hour is recorded, and the kneading time at the point where the kneading torque decreases is displayed.

5) Residual vinyl chloride monomer A certain amount of hinyl chloride III was dissolved in tetrahydrofuran, and the vinyl chloride monomer content in the hinyl chloride resin was determined by gas chromatography.

6) Colorability test: 100 parts of vinyl chloride resin, 2.5 parts of butyltin maleate, and 80 parts of dioctyl phthalate as a plasticizer were mixed, kneaded for 10 minutes on a roll at 160°C, and a sheet of one thickness was taken out. The degree of coloring of the sheet was visually observed.

As is clear from the above examples, when a vinyl compound is polymerized at real temperature using the dispersion stabilizer of the present invention, the particle size distribution is almost the same with good reproducibility, and the particle size The distribution is sharp, each particle is porous and uniform, and the filling specific gravity is large, and the adhesion of scale etc. is hard, and the vinyl chloride-based 1TL11 particles have good thermal stability. The industrial value is extremely high.

Claims (5)

[Claims] (1) 0.1 to 2 copolymerized units containing a 2-pyrrolidone ring
A dispersion stabilizer for suspension polymerization of a vinyl compound, comprising a vinyl alcohol polymer containing 5 mol% and a saponification degree of 50 to 95 mol%. (2) A copolymerized unit containing a 2-pyrrolidone ring contains a group represented by the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (I) (However, R_1 to R_6 each represent a hydrogen atom or an alkyl group) The dispersion stabilizer according to claim 1, which is a copolymerized unit. (3) The dispersion stabilizer according to claim 1 or 2, which has a saponification degree of 65 to 85 mol%. (4) The dispersion stabilizer according to any one of claims 1 to 3, wherein the vinyl alcohol polymer is a saponified vinyl acetate polymer. (5) Claims 1 to 4 wherein the vinyl compound is vinyl chloride.
The dispersion stabilizer according to any one of the above.