JPH09263602A - Production of vinyl chloride polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a vinyl chloride polymer excellent in thermal stability, absorption of a plasticizer and a calendering processability. SOLUTION: (A) a partially saponified polyvinyl alcohol having 1,000-3,000 molecular weight and 70-90mol% degree of saponification, (B) a partially saponified polyvinyl alcohol having <=1,000 molecular weight and 70-85mol% degree of saponification and/or (C) a cellulose derivative are used in the weight ratio (A)/[(B)+(C)] of 95/5 to 30/70 as a dispersing stabilizer and a higher fatty acid ester is also used as a dispersing stabilizer for the production of the objective vinyl chloride polymer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a vinyl chloride polymer, and more specifically, by using a specific dispersant and a higher fatty acid ester, the roll tackiness during molding is improved. In addition, the present invention relates to a method for producing a vinyl chloride-based polymer which has no problem in thermal stability during molding.

[0002]

2. Description of the Related Art In general, vinyl chloride polymers are manufactured into various molded products by a calendering method or an extrusion processing method, and improvement of molding processability is desired in these processing fields. Various methods have been proposed to meet these demands, and Japanese Patent Application Laid-Open No. 48-89991 discloses a method of adding a specific glycerin fatty acid ester,
JP-A-52-36179 proposes a method of using a sorbitan monofatty acid ester in combination with a specific partially saponified polyvinyl alcohol and hydroxypropyl cellulose. Further, in JP-A-2-53808, sorbitan fatty acid ester having HLB of 1 to 4 and hydroxyl value of 50 to 150, partially saponified polyvinyl having a degree of polymerization of 500 to 1500 and a degree of saponification of 85 to 95 mol%. Alcohol and polymerization degree is 200-800 and saponification degree is 30
A method in which ˜60 mol% of partially saponified polyvinyl alcohol is used in combination has been proposed.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The vinyl chloride-based polymer obtained by the method described in JP-A-9991 and JP-A-52-36179 has improved processability, but when an organotin stabilizer is used,
It has a problem that thermal stability is lowered.
Further, the vinyl chloride-based polymer obtained by the method described in JP-A-2-53808 has excellent gelling properties, but has a problem of poor roll adhesion during calendar processing.

Therefore, an object of the present invention is to provide a method for producing a vinyl chloride polymer which is excellent in heat stability, plasticizer absorbability and calender processability.

[0005]

Means for Solving the Problems As a result of diligent studies on the above problems, the present inventors have found that by using a higher fatty acid ester and a specific dispersant in a specific ratio during suspension polymerization, It was found that a vinyl chloride polymer excellent in stability, plasticizer absorbability and calender processability was obtained, and the present invention was completed.

That is, the present invention is a method for producing a vinyl chloride polymer in which a vinyl chloride monomer is subjected to a suspension polymerization method in an aqueous medium.
Less than 00, a partially saponified polyvinyl alcohol (A) having a saponification degree of 70 to 90 mol%, and a partially saponified polyvinyl alcohol (B) having a polymerization degree of 1000 or less and a saponification degree of 70 to 85 mol%, and / or The weight ratio of the cellulose derivative (C) is (A) / ((B) + (C)) = 95.
The present invention relates to a method for producing a vinyl chloride polymer, which comprises using a higher fatty acid and a higher fatty acid ester obtained from a monohydric aliphatic alcohol in a ratio of / 5 to 30/70.

The present invention will be described in more detail below.

The dispersant used in the present invention is a partially saponified polyvinyl alcohol (A) having a polymerization degree of 1000 or more and less than 3000 and a saponification degree of 70 to 90 mol%, and
A partially saponified polyvinyl alcohol (B) having a degree of polymerization of 1000 or less and a degree of saponification of 70 to 85 mol% and / or a cellulose derivative (C), in a weight ratio of (A) /
((B) + (C)) = 95/5 to 30/70.

In the present invention, the partially saponified polyvinyl alcohol (A) used as the dispersant component has a degree of polymerization of 1000 or more and less than 3000 and a degree of saponification of 70 to 90 mol%, preferably 75 to 90 mol%. . Here, the degree of polymerization of the partially saponified polyvinyl alcohol (A) is 10
When the saponification degree is less than 00 or exceeds 90 mol%,
The polymerization dispersion system at the time of polymerization becomes unstable, blocks during the polymerization, and the obtained vinyl chloride polymer particles become coarse. On the other hand, when the saponification degree of the partially saponified polyvinyl alcohol (A) is lower than 70 mol%, the effect of improving the calendering processability becomes insufficient.

In the present invention, the partially saponified polyvinyl alcohol (B) used as a dispersant component has a degree of polymerization of 1000 or less, a degree of saponification of 70 to 85 mol%, and preferably a degree of polymerization of 300 to 1,000. Here, the degree of saponification of the partially saponified polyvinyl alcohol (B) is 70 mol%.
When it is lower, the effect of improving the calendering processability is insufficient, and when the degree of saponification exceeds 85 mol%, the effect of improving the calendering processability is insufficient, and the resulting monomeric properties of the vinyl chloride polymer particles are Poor plasticizer absorption. Further, when the degree of polymerization of the partially saponified polyvinyl alcohol (B) exceeds 1,000, the decomeromer property and plasticizer absorbability of the obtained vinyl chloride polymer particles are deteriorated.

In the present invention, the cellulose derivative (C) used as the dispersant component is excellent in polymerization dispersion stability at the time of polymerization, demomerization property of the obtained vinyl chloride polymer particles, and plasticizer absorbability. Hydroxypropyl methylcellulose having an methoxy substitution degree of 25 to 30% by weight, a hydroxypropoxy substitution degree of 5 to 15% by weight, and a 2% by weight aqueous solution having a viscosity at 20 ° C. of 10 to 100 cps is preferable.

The partially saponified polyvinyl alcohol (A) and the partially saponified polyvinyl alcohol (B) and / or the cellulose derivative (C) used in the present invention are used in a weight ratio of (A) / ((B) + (C). )) = 95/5
It is 30/70. When the proportion of the partially saponified polyvinyl alcohol (A) used is less than 30% by weight, not only the polymerization dispersion system at the time of polymerization becomes unstable, but also the calender processability improving effect becomes insufficient. On the other hand, when the use ratio of the partially saponified polyvinyl alcohol (A) exceeds 95% by weight, the resulting monomer-free vinyl chloride-based polymer particles have a demomer property,
Poor plasticizer absorption. Further, in the present invention, since the vinyl chloride polymer obtained has an excellent balance of plasticizer absorbency and calender processability, (A) / ((B)
+ (C)) = 95/5 to 50/50 is preferably used.

Further, the partially saponified polyvinyl alcohols (A) and (B) may be used in combination of two or more kinds as long as they are in the above-mentioned range.
A modified product may also be used.

As the higher fatty acid ester used in the present invention, any higher fatty acid ester obtained from a higher fatty acid and a monohydric aliphatic alcohol can be used. The higher fatty acid having 5 to 25 carbon atoms and carbon number Two
A higher fatty acid ester consisting of a monohydric aliphatic alcohol of 5 or less is preferable, and a higher fatty acid ester compound consisting of a higher fatty acid having 12 to 25 carbon atoms and a monohydric aliphatic alcohol having 8 to 25 carbon atoms is calenderable. It is particularly preferable because of its excellent improvement effect. Examples of the compounds corresponding to these include octyl palmitate, octyl stearate, butyl stearate, stearyl stearate, stearyl palmitate, 2-ethylhexyl stearate, 2-ethylhexyl behenate, 2-ethylhexyl palmitate, stearyl betaate. Examples thereof include henate, butyl behenate, butyl palmitate, stearyl laurate, palmityl stearate, palmityl palmitate, and the like, and the higher fatty acid ester is one or two.
Combinations of more than one species can be used. Further, when an ester compound composed of an aromatic carboxylic acid and an aliphatic alcohol is used instead of the higher fatty acid ester, the effect of improving the calendering processability of the vinyl chloride polymer obtained is insufficient, and the higher fatty acid and the polyhydric alcohol are used. When such a higher fatty acid partial ester is used, the thermal stability of the resulting vinyl chloride polymer is lowered.

The amount of the higher fatty acid ester used in the present invention is 0 based on 100 parts by weight of the vinyl chloride monomer because the vinyl chloride polymer obtained is excellent in the effect of improving the calendering processability and the gelation property. It is preferably 0.005 to 0.5 parts by weight.

There is no limitation on the method of adding the higher fatty acid ester in the present invention, for example, a method of directly adding it before the polymerization, a method of gradually adding a dispersion liquid dispersed in water during the polymerization, a vinyl chloride system after the polymerization. Examples thereof include a method of adding directly to the polymer slurry or after being dispersed in water and then adding, a method of once dissolving in a soluble solvent and then adding.

In the present invention, it is preferable to use a molecular weight modifier in combination in order to improve the thermal stability of the resulting vinyl chloride polymer. The molecular weight modifier may be one known as a molecular weight modifier in a radical polymerization system, and is a compound having a mercapto group and a hydroxyl group since a vinyl chloride polymer having improved thermal stability can be obtained. It is preferable. As the compound,
For example, 2-mercaptoethanol, 3-mercaptopropanol, 4-mercaptobutanol, thioglycerin, 1-thioglycerol and the like can be mentioned. The amount of these molecular weight regulators used is 0.001 to 0 per 100 parts by weight of the vinyl chloride-based monomer because the vinyl chloride-based polymer obtained has an excellent balance of thermal stability and calender processability. It is preferably 0.05 part by weight. In addition, there is no limitation on the addition method when these molecular weight regulators are used, and examples thereof include a method of directly adding and a method of adding as a solution once dissolved in a soluble solvent.

As the method for producing the vinyl chloride polymer in the present invention, a suspension polymerization method generally used can be applied, and specifically, for example, the following method can be used.

Pure water, a dispersion stabilizer, and a polymerization initiator are put into a jacketed pressure resistant polymerization vessel equipped with a stirrer, and the pressure is reduced. Then, a vinyl chloride-based monomer is press-fitted and the inside of the polymerization vessel is heated with stirring to start polymerization. The polymerization conditions at that time include a polymerization temperature of 20 to 90 ° C. and a polymerization time of 1 to 40 hours. After completion of the polymerization, unreacted vinyl chloride-based monomer is recovered, and a slurry is taken out and dehydrated and dried. By doing so, a vinyl chloride polymer is obtained.

The polymerization initiator used in the present invention may be one generally used as a polymerization initiator in a suspension polymerization method, and examples thereof include diisopropyl peroxydicarbonate, tert-butyl peroxyneodecanate and tert-. Peroxides such as hexyl peroxypivalate and benzoyl peroxide; azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile and the like;
These can be used alone or in combination of two or more.

The vinyl chloride monomer in the present invention means
A vinyl chloride monomer or a mixture of a vinyl chloride monomer and a vinyl-based monomer copolymerizable with a vinyl chloride monomer.

The vinyl-based monomer copolymerizable with the vinyl chloride monomer may be any vinyl-based monomer copolymerizable with the vinyl chloride monomer, such as vinyl acetate. , Vinyl propionate, vinyl caproate, vinyl laurate, vinyl stearate, and other vinyl esters; ethylene, propylene, isobutylene, and other olefins; isobutyl vinyl ether, phenyl vinyl ether, octyl vinyl ether, and other alkyl or aryl vinyl ethers; vinylidene chloride , Halogenated olefins such as vinyl fluoride, allyl chloride and vinyl bromide; ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, stearyl methacrylate. Acrylic or methacrylic acid esters, acrylic acid, methacrylic acid, crotonic acid,
Examples thereof include acrylic derivatives such as acrylonitrile, maleic anhydride, and itaconic anhydride.

Further, in the present invention, a polymer which can be graft-polymerized with a vinyl chloride-based monomer may be added as necessary to carry out the polymerization, and a polymer which can be graft-copolymerized with the vinyl chloride-based monomer. Examples include ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer, chlorinated polyethylene, polyurethane, polybutadiene-styrene-methylmethacrylate copolymer (MBS), polybutadiene-acrylonitrile-
Examples thereof include (α-methyl) styrene copolymer (ABS), polybutyl acrylate, butyl rubber, polystyrene, styrene-butadiene copolymer, and crosslinked acrylic rubber.

In the production method of the present invention, in the initial stage of polymerization,
An antioxidant, a gelation improver, a pH adjuster, a scale inhibitor, etc. may be used as other polymerization additives during or after the polymerization.

[0025]

EXAMPLES Hereinafter, the production method of the present invention will be described based on examples, but the present invention is not limited to these examples.

The roll adhesion, heat stability and plasticizer absorbency in the examples and comparative examples were evaluated by the following methods.

-Amount of Plasticizer Absorbed- An excess amount of plasticizer (dioctyl phthalate; DOP) is added to the obtained polymer, and the mixture is allowed to stand at room temperature for 10 minutes, and then a centrifuge (manufactured by Domestic Centrifuge Co., Ltd.) is used. 3000 rpm
The mixture was centrifuged at 37 ° C. to remove the plasticizer not absorbed by the polymer.
The amount of plasticizer retained in the polymer after centrifugation was measured, and the ratio of the plasticizer to the polymer was expressed as a percentage, which was taken as the plasticizer absorption amount.

-Roll Adhesion- 4 parts by weight of a dibutyltin malate stabilizer and 1.5 parts by weight of a fatty acid ester lubricant were added to 100 parts by weight of the obtained polymer. This compounded composition was applied at a surface temperature of 180 ° C.
The composition was wrapped around a roll with an inch two-roll (manufactured by Kansai Roll Co., Ltd.) and then kneaded for 5 minutes to take out the sheet. Then, the same operation was repeated five times to evaluate the ease of peeling of the sheet.

Evaluation criteria for calendering workability: No tackiness (peeling without problems).

ΔSlightly sticky (easy peeling).

X Large adhesion (somewhat difficult to peel).

XX Strong adhesion (difficulty peeling).

-Thermal Stability- 100 parts by weight of the obtained polymer, 3 parts by weight of dibutyltin malate stabilizer and 1.5 parts by weight of fatty acid ester lubricant are blended, and 300 g of the blend is blended with a roll surface temperature of 150.
The mixture was kneaded for 5 minutes with an 8-inch roll at 0 ° C. to obtain a sheet molded body having a thickness of 1 mm. The time required for blackening the test piece cut out from the sheet molded body was measured in an oven at 190 ° C.

Example 1 In a stainless steel autoclave having an internal volume of 25 liters, 140 parts by weight of pure water, a degree of saponification of 80 mol% and a degree of polymerization of 2600.
Partially saponified polyvinyl alcohol 0.06 parts by weight, saponification degree 73 mol%, partially saponified polyvinyl alcohol 0.02 parts by weight having a degree of polymerization of 800, and tert-hexyl peroxypivalate 0.025 parts by weight are put in a reduced pressure state. I chose Next, 100 parts by weight of a vinyl chloride monomer was charged,
Polymerization was carried out by heating to 65 ° C. while stirring the inside of the autoclave. When the pressure in the autoclave dropped 1.8 kg / cm ² from the pressure in the steady state of the polymerization reaction, unreacted vinyl chloride monomer was recovered. The polymerization time was 6 hours.

After recovering the unreacted vinyl chloride monomer, 2
-Ethylhexyl stearate is vinyl chloride polymer 1
When 0.2 part by weight was added to 100 parts by weight, the slurry was taken out from the autoclave and dehydrated and dried to obtain a vinyl chloride polymer with a polymerization conversion rate of about 85%.

The evaluation results of the obtained vinyl chloride polymer are shown in Table 1.

The obtained vinyl chloride polymer had a high plasticizer absorbability, excellent heat stability and calender processability.

Example 2 Dispersant system: 80 mol% of saponification degree, 0.07 part by weight of partially saponified polyvinyl alcohol having a polymerization degree of 2600, methoxy substitution degree of 29 weight%, hydroxypropoxy substitution degree of 9.5 weight parts. %, 2 wt% aqueous solution having a viscosity at 20 ° C. of 50 cps of 0.02 parts by weight of hydroxypropylmethyl cellulose (hereinafter abbreviated as HPMC), and 0.1 parts by weight of stearyl stearate instead of 2-ethylhexyl stearate. Except for this, the same procedure as in Example 1 was carried out to obtain a vinyl chloride polymer with a polymerization conversion rate of about 85%.

Table 1 shows the evaluation results of the obtained vinyl chloride polymer.

The obtained vinyl chloride polymer was excellent in plasticizer absorbability, heat stability and calender processability.

Example 3 A dispersant system was prepared by adding 0.07 part by weight of a partially saponified polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 2600, and a partially saponified polyvinyl alcohol having a saponification degree of 73 mol% and a polymerization degree of 800. 0.01 parts by weight, the degree of methoxy substitution is 29% by weight, the degree of hydroxypropoxy substitution is 9.5% by weight, and the viscosity of a 2% by weight aqueous solution is 50 cps at 20 ° C.
The same procedure as in Example 1 was conducted except that PMC was 0.01 part by weight and 0.1 part by weight of butyl behenate was used instead of 2-ethylhexyl stearate to obtain a vinyl chloride polymer with a polymerization conversion rate of about 85%. It was

Table 1 shows the evaluation results of the obtained vinyl chloride polymer.

The obtained vinyl chloride polymer was excellent in plasticizer absorbency, heat stability and calender processability.

Example 4 A dispersant system was prepared by adding 0.05 part by weight of partially saponified polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 2600, and a partially saponified polyvinyl alcohol having a saponification degree of 73 mol% and a polymerization degree of 800. 0.05 parts by weight, 29% by weight of methoxy substitution, 9.5% by weight of hydroxypropoxy substitution, 2% by weight of an aqueous solution having a viscosity of 50 cps at 20 ° C.
PMC is 0.01 part by weight, and 2- as a molecular weight regulator.
58 ° C with 0.03 parts by weight of mercaptoethanol
Polymerization was carried out in the same manner as in Example 1 except that 0.2 parts by weight of steryl stearate was used instead of 2-ethylhexyl stearate to obtain a vinyl chloride polymer with a polymerization conversion rate of about 85%.

Table 1 shows the evaluation results of the obtained vinyl chloride polymer.

The resulting vinyl chloride polymer was excellent in plasticizer absorbency, calender processability, and particularly thermal stability.

Comparative Example 1 0.06 parts by weight of a partially saponified polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 2600 was used as a dispersant system, and a partially saponified polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 600 was used. A vinyl chloride polymer was obtained at a polymerization conversion rate of about 85% by repeating the same procedure as in Example 1 except that 0.04 parts by weight was used and 2-ethylhexyl stearate was not used.

The evaluation results of the obtained vinyl chloride polymer are shown in Table 2.

The obtained vinyl chloride polymer was inferior in releasability from the roll of the sheet and had poor calendering property.

Comparative Example 2 A dispersant system was prepared by using 0.08 part by weight of a partially saponified polyvinyl alcohol having a degree of saponification of 80 mol% and a degree of polymerization of 2,600, and palmitic stearate was used in place of 2-ethylhexyl stearate. A vinyl chloride polymer was obtained in the same manner as in Example 1 except that 1 part by weight was used, with a polymerization conversion of about 85%.

The evaluation results of the obtained vinyl chloride polymer are shown in Table 2.

The obtained vinyl chloride polymer had poor plasticizer absorbability.

Comparative Example 3 A dispersant system was prepared by adding 0.02 part by weight of a partially saponified polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 2600, and a partially saponified polyvinyl alcohol having a saponification degree of 73 mol% and a polymerization degree of 800. A vinyl chloride polymer was used in the same manner as in Example 1 except that 0.08 part by weight was used and 0.1 part by weight of palmityl stearate was used instead of 2-ethylhexyl stearate at a polymerization conversion rate of about 85%. Got

The evaluation results of the obtained vinyl chloride polymer are shown in Table 2.

The obtained vinyl chloride polymer was inferior in peelability from the roll of the sheet and had poor calendering property.

Comparative Example 4 A dispersant system was prepared by adding 0.05 part by weight of a partially saponified polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 2600 and a partially saponified polyvinyl alcohol having a saponification degree of 73 mol% and a polymerization degree of 800. 0.01 parts by weight, the degree of methoxy substitution is 29% by weight, the degree of hydroxypropoxy substitution is 9.5% by weight, and the viscosity of a 2% by weight aqueous solution is 50 cps at 20 ° C.
PMC was 0.02 parts by weight, and sorbitan monostearate was added in place of 2-ethylhexyl stearate.
Example 2 was repeated except that 2 parts by weight was used.
% Of vinyl chloride polymer was obtained at a polymerization conversion of 0.1%.

The evaluation results of the obtained vinyl chloride polymer are shown in Table 2.

The vinyl chloride polymer obtained was inferior in thermal stability.

Comparative Example 5 A dispersant system was prepared by adding 0.06 part by weight of a partially saponified polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 2600, and a partially saponified polyvinyl alcohol having a saponification degree of 73 mol% and a polymerization degree of 800. 0.01 parts by weight, except that 0.1 parts by weight of distearyl phthalate was used instead of 2-ethylhexyl stearate, the same procedure as in Example 1 was repeated to obtain a vinyl chloride polymer at a polymerization conversion rate of about 85%. Obtained.

Table 3 shows the evaluation results of the obtained vinyl chloride polymer.

The obtained vinyl chloride polymer was inferior in peelability from the roll of the sheet and had poor calendering property.

Comparative Example 6 A dispersant system was prepared by adding 0.06 part by weight of a partially saponified polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 2600 and a partially saponified polyvinyl alcohol having a saponification degree of 48 mol% and a polymerization degree of 300. 0.02 parts by weight, and 0.1% palmityl stearate instead of 2-ethylhexyl stearate.
The same procedure as in Example 1 was carried out except that the amount by weight was about 85%.
A vinyl chloride polymer was obtained at a polymerization conversion ratio of.

Table 3 shows the evaluation results of the obtained vinyl chloride polymer.

The obtained vinyl chloride polymer was inferior in peelability from the roll of the sheet and had poor calendering property.

Comparative Example 7 0.05 part by weight of a partially saponified polyvinyl alcohol having a saponification degree of 88 mol% and a polymerization degree of 500 was used in a dispersant system, and 73 parts of a saponification degree of 73 mol% and a polymerization degree of 800 were partially saponified polyvinyl alcohol. The procedure of Example 1 was repeated except that the amount was 0.03 part by weight, but vinyl chloride polymer particles could not be obtained due to blocking during polymerization.

Comparative Example 8 A dispersant system was prepared by adding 0.08 part by weight of a partially saponified polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 2600 and a partially saponified polyvinyl alcohol having a saponification degree of 73 mol% and a polymerization degree of 800. 0.001 parts by weight, methoxy substitution is 29% by weight, hydroxypropoxy substitution is 9.5% by weight, 2
0.001 parts by weight of HPMC having a viscosity of 50 cps at 20 ° C. in an aqueous solution of 20% by weight was used, and palmityl stearate was used in place of 2-ethylhexyl stearate.
Example 1 was repeated except that 1 part by weight was used.
% Of vinyl chloride polymer was obtained at a polymerization conversion of 0.1%.

Table 3 shows the evaluation results of the obtained vinyl chloride polymer.

The vinyl chloride polymer obtained was inferior in plasticizer absorbency.

Comparative Example 9 A dispersant system was prepared by adding 0.05 part by weight of a partially saponified polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 2600 and a partially saponified polyvinyl alcohol having a saponification degree of 88 mol% and a polymerization degree of 600. 0.05 parts by weight, and 0.1% palmityl stearate instead of 2-ethylhexyl stearate.
The same procedure as in Example 1 was carried out except that the amount by weight was about 85%.
A vinyl chloride polymer was obtained at a polymerization conversion ratio of.

Table 4 shows the evaluation results of the obtained vinyl chloride polymer.

The obtained vinyl chloride polymer was inferior in plasticizer absorbability and calender processability.

Comparative Example 10 Dispersant system: saponification degree: 95 mol%; partially saponified polyvinyl alcohol having a degree of polymerization of 1500; 0.08 parts by weight; saponification degree: 73 mol%; partially saponified polyvinyl alcohol having a degree of polymerization of 800. Was carried out in the same manner as in Example 1 except that the amount was 0.01 part by weight, but vinyl chloride polymer particles could not be obtained due to blocking during polymerization.

[0073]

[Table 1]

[0074]

[Table 2]

[0075]

[Table 3]

[0076]

[Table 4]

[0077]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a vinyl chloride polymer having improved roll tackiness during molding and good heat stability and plasticizer absorbability. It's a very big one.

Claims (3)

[Claims] 1. A method for producing a vinyl chloride polymer, which comprises subjecting a vinyl chloride monomer to suspension polymerization in an aqueous medium, wherein the dispersant has a degree of polymerization of 1,000 or more and less than 3000 and a degree of saponification of 70 to 90 mol. % Of partially saponified polyvinyl alcohol (A), polymerization degree of 1000 or less, saponification degree of 70-
85 mol% partially saponified polyvinyl alcohol (B),
And / or cellulose derivative (C) is used in a weight ratio of (A) / ((B) + (C)) = 95/5 to 30/70, and higher fatty acid and monovalent aliphatic A method for producing a vinyl chloride polymer, which comprises adding a higher fatty acid ester obtained from alcohol. 2. The method for producing a vinyl chloride polymer according to claim 1, further comprising adding a molecular weight modifier. 3. The cellulose derivative has a methoxy substitution degree of 25.
-30% by weight, hydroxypropoxy substitution degree 5-15% by weight, 2% by weight aqueous solution has a viscosity of 10-1 at 20 ° C.
The method for producing a vinyl chloride-based polymer according to claim 1 or 2, which is hydroxypropyl methylcellulose having a rate of 00 cps.