JPH10101715A - Production of vinyl chloride polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a vinyl chloride polymer which can produce a polymer that has no significant tackiness to a roll at the time of calendering and possesses improved absorption of a plasticizer and thermal stability by suspension-polymerizing a vinyl chloride monomer in the presence of an oil-soluble polymn. initiator, a specified dispersant, a higher alcohol and/or a higher fatty acid deriv. in an aq. medium. SOLUTION: A vinyl chloride monomer in an amt. of 100 pts.wt. is suspension-polymerized in an aq. medium in the presence of an oil-soluble polymn. initiator, a dispersant comprising 0.04 to 0.2 pt.wt. in total of a partially saponified polyvinyl alcohol having an average degree of polymn. of 1,000 to 3,000 and a degree of saponification of 70 to 90mol% and a partially saponified polyvinyl alcohol having an average degree of polymn. of 500 to 900 and a degree of saponification of 70 to 80mol% in a wt. ratio of (1:9) to (9:1), and 0.005 to 0.03 pt.wt. partially saponified polyvinyl alcohol having an average degree of polymn. of 200 to 600 and a degree of saponification of 20 to 55mol%, and 0.05 to 0.5 pt.wt. higher alcohol and/or higher fatty acid deriv., thereby obtaining a vinyl chloride polymer having an average degree of polymn. of 400 to 1,500.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a vinyl chloride polymer. More particularly, the present invention relates to a method for producing a vinyl chloride polymer which is porous, has excellent plasticizer absorption and thermal stability, and has little roll adhesion during calendering.

[0002]

2. Description of the Related Art Vinyl chloride polymers are used in a wide range of fields from hard to soft because they are well-balanced polymer materials in processability, physical properties and price. Among these, in the field of softness, since a relatively large amount of a plasticizer is added to the vinyl chloride polymer, it is desired that the plasticizer absorbs the plastic at a high rate and that the obtained molded article has less fish eyes. In order to improve the plasticizer absorption, the particles of the vinyl chloride polymer must be made more porous.
No. 36089 discloses that a partially saponified polyvinyl alcohol (saponification degree: 70 to 90 mol%, average polymerization degree: 700 to 2600) used as a main dispersant has a saponification degree of 60 mol% or less and an average polymerization degree. A method has been proposed in which partially saponified polyvinyl alcohol having a low saponification degree and a low polymerization degree of 500 or less is used in combination as a secondary dispersant.

However, when a large amount of the secondary dispersant is used in combination, the plasticizer absorption of the obtained vinyl chloride polymer is improved, but when the vinyl chloride polymer is subjected to calendering, the molten resin is However, there is a problem that sticking to the roll or plate-out is likely to occur, and the calenderability is deteriorated.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have aimed at obtaining a vinyl chloride polymer which is porous, has excellent plasticizer absorbency, has low roll adhesion during calendering, and has excellent heat stability. Diligently studied. As a result, a partially saponified polyvinyl alcohol having a specific average polymerization degree and saponification degree is obtained.
The polymer obtained by suspension polymerization of a vinyl chloride-based single compound in the presence of a specific higher alcohol and / or a higher fatty acid derivative in the presence of a specific amount of three types of specific alcohols as a dispersing agent is porous. It has been found that a vinyl chloride polymer having excellent plasticizer absorbency, low roll adhesion during calendering, and excellent heat stability can be obtained. Based on this finding, the present invention has been completed. . As apparent from the above description, an object of the present invention is to provide a vinyl chloride polymer which is porous, has excellent plasticizer absorbency, has low roll adhesion during calendar processing, and has excellent heat stability. It is to provide a manufacturing method.

[0005]

According to the present invention, as a means for solving the above-mentioned problems, vinyl chloride monomers are subjected to suspension polymerization in an aqueous medium in the presence of an oil-soluble polymerization initiator. As a dispersant used for suspending and dispersing the monomer, (A) a partially saponified polyvinyl alcohol having an average degree of polymerization of 1000 to 3000 and a degree of saponification of 70 to 90 mol%, and (B) an average degree of polymerization of 500 Using a partially saponified polyvinyl alcohol having a saponification degree of from about 900 to about 900 and a degree of saponification of from 70 to 80 mol%, and (C) a partially saponified polyvinyl alcohol having an average degree of polymerization of from 200 to 600 and a saponification degree of from about 20 to 55 mol%. And polymerizing a vinyl chloride-based single compound in the presence of a higher alcohol and / or a higher fatty acid derivative.

Hereinafter, the present invention will be described in detail. The weight ratio (A) / (B) of the amounts of the dispersants (A) and (B) used in the present invention is 9/1 to 1/9, preferably 7/3.
3/7, and the total of the charged amounts of (A) and (B) is
It is used in a ratio of 0.04 to 0.2 parts by weight per 100 parts by weight of the monomer. The weight ratio of (A) / (B) is 9/1
If the ratio exceeds, the plasticizer absorption of the obtained polymer particles may be deteriorated. If the ratio is less than 1/9, the obtained polymer particles may be fine and powder handling may be difficult. If the total of the charged amounts of (A) and (B) is less than 0.04 parts by weight per 100 parts by weight of the charged monomer, the dispersion of the monomer becomes unstable, and as a result, the weight of the particles increases. No coalesced particles are obtained, or even if they are obtained, the polymer particles tend to be coarse, and if it exceeds 0.2 parts by weight, the obtained polymer particles become fine and powder handling Becomes difficult.

In the method for producing a vinyl chloride polymer according to the present invention, in addition to the dispersants (A) and (B), the dispersant (C) is further added to the mixture at a rate of 0.005 per 100 parts by weight of the monomer.
Used in the range of 0.03 parts by weight. When the degree of saponification of the dispersant (C) is lower than 20 mol%, the obtained polymer may be coarsened, scale may adhere to the polymerization vessel, and the degree of saponification may be higher than 55 mol%. If the degree of polymerization exceeds 600, the resulting polymer will have poor plasticizer absorbency.
On the other hand, if the amount exceeds 0.03 parts by weight, the obtained polymer particles may be fine and handling of the powder may be difficult. Further, the method of adding the partially saponified polyvinyl alcohol (C) is not particularly limited. For example, the partially saponified polyvinyl alcohol may be added directly as it is, or a solvent such as methanol, acetone, methyl acetate, ethyl acetate or a water / organic solvent. It may be used by dissolving it using a mixed solvent, or it may be made into an aqueous emulsion and added to the polymerization system.

The higher alcohol used in the present invention includes lauryl alcohol, palmityl alcohol, stearyl alcohol, cetyl alcohol and the like. The higher fatty acid derivatives include sorbitanic acid monolaurate and sorbitanic acid monopalmitate Sorbitan monostearate, sorbitan trilaurate, sorbitan tripalmitate, sorbitan tristearate, glycerin monolaurate, glycerin monopalmitate, glycerin monostearate, glycerin trilaurate, glycerin tripalmitate, glycerin tri Stearate and the like can be mentioned, and these may be used alone or in combination of two or more. Further, the preferred amount of these additives is 0.05 to 0.5 parts by weight per 100 parts by weight of the charged monomers. If the adhesiveness cannot be sufficiently improved, and if the content exceeds 0.5 parts by weight, the transparency of a molded article using the obtained polymer deteriorates.

When the above additives are added to the polymerization system, it is preferable to add them all at once before the start of the polymerization.
If added at once or dividedly after the start of polymerization, the plasticizer absorbency of the obtained polymer will not be improved, and the transparency of the molded article using the obtained polymer will decrease or the fish eye will increase. I do.

The vinyl chloride monomer used in the present invention includes, in addition to the vinyl chloride monomer, a polymerizable compound having a vinyl group at one end capable of copolymerizing with the vinyl chloride monomer and the vinyl chloride monomer. It is a mixture with a monomer, and the polymerizable compound is not particularly limited as long as it can be copolymerized with a vinyl chloride monomer.Specifically, alkyl vinyl esters such as vinyl acetate and cetyl vinyl ether are used. Examples thereof include alkyl vinyl ethers, α-monoolefin monomers such as ethylene or propylene, and comonomers such as alkyl acrylates such as methyl acrylate or alkyl methacrylates such as methyl methacrylate. .

The oil-soluble polymerization initiator used in the present invention includes tertiary butyl peroxy neodecanoate,
Tertiary butyl peroxypivalate, perester compounds such as α-cumylperoxy neodecanoate,
Diisopropylperoxydicarbonate, dicyclohexylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, bis (4-tert-butylcyclohexyl) peroxydicarbonate,
Di-3-methoxybutylperoxydicarbonate, di-3-methoxy-3-methylbutylperoxydicarbonate, percarbonate compounds such as disi-butylbutylperoxydicarbonate, peroxides such as acetylcyclohexylsulfonyl peroxide, and α,
An azo compound such as α'-azobis-4-methoxy-2-, 4-dimethylvaleronitrile can be mentioned, and one or more of these can be used in combination.

[0012] In addition, as long as the effects of the present invention are not impaired,
Usually, other additives used for the suspension polymerization, for example, a chain transfer agent for adjusting the average degree of polymerization, such as a stabilizer capable of preventing scale adhesion to the inner wall of the polymerization vessel, an antioxidant, etc. A foaming agent, a pH adjusting agent for adjusting the pH of the aqueous polymerization medium, or the like may be added without any problem.

In the method for producing a vinyl chloride polymer of the present invention, for example, the amount of an aqueous medium used per charged monomer, a polymerization initiator and a vinyl chloride monomer, and if necessary, other comonomers, etc. Consumption of these and their preparation methods,
The polymerization temperature and the like may be performed under conventionally known conditions.

As the metal stabilizer to be incorporated in the vinyl chloride polymer obtained in the present invention, not only an organotin stabilizer but also a composite metal soap stabilizer can exhibit sufficiently excellent thermal stability. The effect of the present invention is greater when a tin-based stabilizer is used.

As the organotin-based stabilizer, an ordinary organotin-based stabilizer for a vinyl chloride polymer is used, and there is no particular limitation. The composite metal soap stabilizer may be a combination of an organic acid salt of zinc and an organic acid salt of an alkali metal and / or an alkaline earth metal.
Alternatively, examples of the kind of the alkaline earth metal include lithium, sodium, potassium, magnesium, calcium and the like, and among them, a combination of calcium and zinc is preferable. Examples of the organic acid salt include, but are not limited to, carboxylic acids such as formic acid, acetic acid, propionic acid, caprylic acid, lauric acid, palmitic acid, and stearyl acid.

[0016]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In addition, the evaluation method of the roll adhesiveness and the thermal stability of the molded article performed in Examples and Comparative Examples was based on the following methods.

(1) Evaluation of Roll Adhesion Roll adhesion temperature: 100 parts by weight of vinyl chloride polymer, 1.2 parts by weight of dibutyltin malate stabilizer, 2.5 parts by weight of epoxidized soybean oil, 0.3 parts of stearic acid Weigh parts by weight, put in Henschel mixer (trade name), 1000r
Stir at pm for 10 minutes to blend. After winding 100 g of the obtained compound at 170 ° C. using an 8-inch electric roll, the mixture is kneaded while heating to 200 ° C. at a heating rate of 1 ° C./min. The temperature at which sticking to the surface was not possible was measured. It means that the higher the temperature is, the harder it is to stick to the roll.

Roll adhesion: 100 g of the above composition was kneaded with an 8-inch roll at a roll temperature of 180 ° C. for 5 minutes, and a sheet was taken out. Next, the composition was newly kneaded for 5 minutes and the sheet was taken out. This operation was repeated until the sheet was stuck to the 8-inch roll and the sheet was cut and could not be taken out, and the number of times at that time was judged. The criteria for judgment are as follows.

(2) Thermal Stability of Molded Product The above composition was kneaded with an 8-inch roll at 160 ° C. for 5 minutes to form a sheet having a thickness of about 0.5 mm, which was placed in an oven at 185 ° C. and the sheet was blackened. Remove every 10 minutes until carbonization occurs. The longer the blackening time of these sheets, the better the thermal stability.

(3) Transparency of molded article (haze value) The above-mentioned sheets were overlaid and pressed under the conditions of 160 ° C and 100 kg / cm ² to prepare a pressed plate having a thickness of 5 mm. The transparency (haze value) of this press plate was measured using a color computer manufactured by Suga Test Instruments Co., Ltd. The lower the haze value, the higher the transparency.

(4) Amount of plasticizer absorption A glass fiber having an inner diameter of 25 mm and a depth of 85 mm is filled with glass fiber, and 10 g of a sample vinyl chloride polymer is sampled and put into the glass fiber. To this, 20 g of dioctyl phthalate is added, and left for 60 minutes to allow the DOP to sufficiently penetrate into the polymer. Thereafter, the mixture is rotated at 3000 rpm for 30 minutes to centrifuge excess DOP, and the amount (% by weight) of DOP absorbed by the polymer is determined by the mass per 100 parts by weight of the polymer.

EXAMPLE 1 100 k of pure water was placed in a stainless steel polymerization tank having an inner volume of 0.2 m ^3.
g of the partially saponified polyvinyl alcohol having a degree of saponification of 72 mol% and an average degree of polymerization of 760.
75 g (0.025 parts by weight per 100 parts by weight of charged monomer) and 30.00 g of partially saponified polyvinyl alcohol having a degree of saponification of 80 mol% and an average degree of polymerization of 2600 (0.04 part by weight per 100 parts by weight of charged monomer) In water) and a partially saponified polyvinyl alcohol 15.0 having a degree of saponification of 35 mol% and an average degree of polymerization of 250.
0 g (0.02 parts by weight per 100 parts by weight of charged monomer)
Was dissolved in a mixed solvent (weight 1: 1) of methyl alcohol and water, and then 37.5 g of palmityl alcohol (0.05 part by weight per 100 parts by weight of the charged monomer) was started. As an agent, 35 g of t-butyl neodecanoate was added. Further, 75 kg of a vinyl chloride monomer was charged, and the polymerization tank was stirred for 6 hours while stirring.
The temperature was raised to 7 ° C., and when the internal pressure of the polymerization reactor dropped to 9 kg / cm ² , the reaction was stopped. Then, the unreacted monomer was recovered, and the reactants in the polymerization tank were washed with water, dehydrated, dried, and chlorided. A vinyl polymer was obtained. The above-mentioned evaluation test was performed using the obtained polymer particles, and the results are shown in Table 1.

Examples 2 to 3 and Comparative Examples 1 to 2 The procedure of Example 1 was repeated except that the types and the amounts of partially saponified polyvinyl alcohol, higher alcohols and higher fatty acid derivatives were changed to the conditions shown in Table 1. And polymerize,
Polymer particles were obtained. The above-mentioned evaluation test was performed using the obtained polymer particles, and the results are shown in Table 1.

Examples 4 to 6 and Comparative Example 3 The procedure of Example 1 was repeated except that the types and the amounts of partially saponified polyvinyl alcohol, higher alcohols and higher fatty acid derivatives were changed to the conditions shown in Table 2. Perform polymerization,
Polymer particles were obtained. The above evaluation test was performed using the obtained polymer particles, and the results are shown in Table 2.

Comparative Examples 4 to 8 Polymerization was carried out in the same manner as in Example 1 except that the kind and combination of partially saponified polyvinyl alcohol, higher alcohol and higher fatty acid derivative were changed to the conditions shown in Table 3.
Polymer particles were obtained. The above-mentioned evaluation test was performed using the obtained polymer particles, and the results are shown in Table 3.

[0026]

According to the production method of the present invention, compared with the method of improving the plasticizer absorbency by the conventional suspension polymerization method (Comparative Example 1), the plasticizer absorbability is higher and there is a concern about the calender. It is possible to obtain polymer particles having low roll adhesion during processing and good thermal stability.

[Table 1]

[Table 2]

[Table 3]

Claims (2)

[Claims] When a vinyl chloride monomer is subjected to suspension polymerization in an aqueous medium in the presence of an oil-soluble polymerization initiator, the dispersant (A) has an average degree of polymerization of 1,000 to 3,000 and a degree of saponification of 70-90 mol% of partially saponified polyvinyl alcohol, (B) partially saponified polyvinyl alcohol having an average degree of polymerization of 500-900 and a saponification degree of 70-80 mol%,
And (C) a partially saponified polyvinyl alcohol having an average degree of polymerization of 200 to 600 and a degree of saponification of 20 to 55 mol%, and the total amount of the components A and B charged per 100 parts by weight of the monomer is 0.04 to 0.2 parts by weight, (A) /
(B) = 1/9 to 9/1, and the charge amount of (C) is monomer 1
A method for producing a vinyl chloride-based polymer, wherein 0.005 to 0.03 parts by weight per 00 parts by weight is used and polymerization is carried out in the presence of a higher alcohol and / or a higher fatty acid derivative. 2. The process for producing a vinyl chloride polymer according to claim 1, wherein the average degree of polymerization of the obtained vinyl chloride polymer is in the range of 400 to 1500.