JPH01113413A - Manufacture of vinyl chloride polymer - Google Patents

Abstract

PURPOSE:To produce the title polymer that gives a molded product which exhibits a fine texture and matte state, and has a high tensile strength and a high tensile elongation, by subjecting vinyl chloride to aqueous suspension polymerization using a specific mixed catalyst under specific polymerization conditions. CONSTITUTION:Vinyl chloride or a mixture thereof with a monomer polymerizable therewith are fed to a polymerizer, and subjected to aqueous suspension polymerization in the presence of a catalyst. In the polymerization, as the catalyst, diisobutylyl peroxide or dicyclohexylcarbonyl peroxide is used together with a catalyst having a 10-hr half-life period temperature of 50 deg.C or above [e.g., 2,2'-azobis (2,4-dimethylvalero-nitrile)], the polymerization temperature is maintained at 20-28 deg.C until the degree of polymerization reaches 60-85%, and then the polymerization temperature is raised to 50-70 deg.C. A PVC polymer is obtained that gives a molded product which exhibits a smooth texture and matte state, and is excellent in mechanical properties, i.e., tensile strength and tensile elongation.

Description

[Detailed description of the invention] (Industrial field of application) The present invention relates to a method for producing a vinyl chloride polymer,
More specifically, the present invention relates to a method for producing a vinyl chloride polymer that exhibits a supple matte surface on the surface of a molded product and has excellent mechanical properties.

(Prior art) Molded products using vinyl chloride polymers can be adjusted in hardness by changing the amount of plasticizer added to the vinyl chloride polymer, and also have good weather resistance and flame retardancy. It has excellent mechanical properties and is widely used in various processing fields. However, molded products using vinyl chloride polymers generally tend to have uneven gloss during processing.

In recent years, there has been an increasing demand for so-called matte products made from synthetic resins, mainly used in daily necessities, interior decoration items, and vehicle parts. There is an increasing demand for compositions that have the following properties.

Various methods have been tried to matte finish molded products of vinyl chloride resins. For example, there are methods such as adding texture to the surface of the molded product and methods of applying matte paint to the surface of the molded product.The former method is easy to apply to injection molded products, but is difficult to apply to extrusion molded products. Regarding the latter, there is a problem in that the number of molding steps increases and the molding requires more equipment and time, leading to an increase in cost. There is also a method of adding a large amount of filler such as heavy calcium carbonate to the resin, but this method improves the tensile strength of the processed product, aging and/or deterioration due to heating, brittleness, embrittlement temperature, oil resistance,
Accompanied by an extreme decrease in rebound resilience, etc.

In order to improve all of these, we have recently developed a polymer in which diallyl ester of phthalic acid is copolymerized with vinyl chloride, and also in the presence of a polyfunctional compound having two or more ethylenic double bonds in the molecule. A gel that is completely polymerized and has a crosslinked structure that makes it insoluble in tetrahydrofuran (hereinafter referred to as THFJ), which is a solvent for vinyl chloride polymer (hereinafter referred to as rPVcJ).
C' is processed to produce a molded product with a matte surface. However, these are PVC
Because a part of the material has already been cross-linked to the point where it becomes insoluble in THF, the processability is very poor with normal molding methods, and as a matter of course, there is an unmelted part during processing, resulting in poor mechanical properties, especially tensile strength. Its uses are limited due to its low strength and low tensile elongation.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for producing PvC that provides a molded compound with a fine-grained matte state, high tensile strength, and large tensile elongation. .

[Failure to solve the problem]

The present invention relates to vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable with vinyl chloride (hereinafter referred to as "vinyl chloride etc.").

) A method for producing a vinyl chloride polymer by charging the entire polymer into a polymerization vessel and carrying out aqueous suspension polymerization in the presence of a catalyst, in which diisoptyryl peroxide or hashicyclohexyl carbonyl peroxide and 10
Using a catalyst with a time half-life temperature of 50°C or higher and polymerization reaction temperature of 20 to 28°C until the polymerization rate reaches 60 to 85%.
After maintaining the temperature at 50 to 70 degrees Celsius, the polymerization temperature is raised to 50 to 70 degrees Celsius to carry out the polymerization.

In the present invention, vinyl chloride or the like is suspension polymerized according to a known method. Therefore, the aqueous medium used in the present invention means an aqueous solution containing mainly water, a small amount of a suspending agent, and other water-soluble additives (for example, a scale adhesion inhibitor and a pH adjuster) as necessary.

The suspending agent may be one or more of polyvinyl alcohol (including partially saponified polyvinyl acetate), cellulose derivatives such as methylcellulose, folivinylpyrrolidone, maleic anhydride-vinyl acetate copolymer, etc. 1゜The method of the present invention is mainly applied to suspension polymerization of vinyl chloride monomer, but mixtures can be used.
It can also be applied to copolymerization with vinyl monomers that are copolymerizable with vinyl chloride monomers of less than 10%. Vinyl monomers that can be copolymerized with vinyl chloride monomers include alkyl vinyl esters such as vinyl acetate, alkyl vinyl ethers such as cetyl vinyl ether, and α-monomers such as ethylene and propylene.
- Monoolefinic monomers, acrylic acid alkyl esters such as methyl acrylate, or methacrylic acid alkyl esters such as methyl methacrylate, etc. may be mentioned.

As a catalyst, diisoptyryl peroxide or 1d dicyclohexyl carbonyl peroxide and a catalyst having a 10-hour half-life temperature of 50° C. or higher are used in combination. Catalysts with a 10-hour half-life temperature of 50°C or higher include 2.2'-
Azobis (2゜4-dimethylvaleronitrile), 2.2
'-azobisisobutyronitrile, dimethyl-2,2'
-azobisisobutyre), 2,2'-azobis(2-
azo compounds such as methylbutyronitrile), alkyl peroxy esters such as t-butylperoxyvivalate, t-butylperoxyisobutyrate, t-butylperoxyimprobyl carbonate, and t-butylperoxyacetate; Dialkyl peroxides such as mil peroxide, di-t-butyl peroxide, and diacyl peroxides such as lauroyl peroxide, acetyl peroxide, benzoyl peroxide, etc. may be used.

When a catalyst is used in combination, the polymerization temperature is maintained at 20-28°C until the polymerization rate reaches 60-85%, and then the polymerization temperature is 50-70°C.
This is to raise the level. That is, for example, when diimbutyryl peroxide or dicycloheyacyl carbonyl peroxide alone is used, the polymerization temperature is 50° C. from 20 to 28° C.
The catalyst loses its activity when the temperature is raised to ~70°C, and does not contribute to the reaction at 50-70°C. On the other hand 1
In the case of a single catalyst with a 0-hour half-life temperature of -50°C or higher, there is almost no decomposition at the polymerization temperature of 20 to 28°C in the first half, and it takes a long time to reach a polymerization rate of 60 to 85%, which is not realistic. . For this reason, when used in combination, it is suitable for efficiently obtaining the desired polymer.

As a catalyst used in combination with diisoptyryl peroxide or dicyclohexylcarboel peroxide, it is recommended to use a catalyst with a 10-hour half-life temperature of 50°C or more because a catalyst with more activity will become active when the temperature is raised to 50 to 70°C. This is because it disappears.

The reason for using diisoptyryl peroxide or dicyclohexyl carbonyl peroxide is that at a polymerization temperature of 20 to 28°C, other catalysts require a long period of time to obtain a polymerization rate of 60 to 85% in the first stage. A reaction is necessary, and although the time can be shortened by increasing the amount, it impairs the thermal stability of the resulting polymer, which is undesirable.

Polymerization is carried out at a polymerization temperature of 20-85% until the polymerization rate reaches 60-85%.
After maintaining the temperature at 28°C, the polymerization temperature is raised to 5-0 to 70°C to complete the polymerization. If the initial polymerization temperature is higher than 28° C., the degree of polymerization of the resulting polymer will not increase and it will be completely dissolved during processing, resulting in an insufficient matte state. If the temperature is lower than 20°C, the degree of polymerization will be too high and there will be a polymer portion that is not completely dissolved, so the matte state will be good but the physical strength will deteriorate. On the other hand, if the temperature in the second half is lower than 50°C, a polymer with a very low degree of polymerization cannot be obtained, so the difference in solubility from the polymer with a high degree of polymerization produced in the first half remains the same, resulting in a matte state. It becomes insufficient. If the temperature is higher than 70°C, the degree of polymerization of the polymer produced in this portion will be too low, resulting in a decrease in physical strength.

The surface condition of the molded product made by heating and kneading the combined compound is extremely fine and matte, and since this polymer does not have a crosslinked structure that does not dissolve in THF, there is no unmelted part during processing, so it has high mechanical strength, that is, tensile strength. It is far superior to matte molded products made using conventional technology in terms of elongation and tensile elongation.

(Example〕 Examples will be described below, but the present invention is based on these examples.

(1) Determination of matte state Vinyl chloride monomer 100! Okibe' DOP
50 epoxy stabilizer
2 0.6 g of Ca-8t and 0.9 g of Zn-8t were blended and kneaded for 10 minutes on a heated four-wheeler at 160"C to a thickness of 0.6 g.
311 seat? create.

The surface condition of the film obtained by the above method was observed with the naked eye and judged as follows. .

×: Glossy.

Δ: Slightly glossy.

0: Matte state.

(2) Measurement of tensile strength and tensile elongation Four sheets obtained in (1) were stacked and pressed at 170°C for 2 minutes at a pressure of 100#/cdG to obtain a thickness of 1. A sheet of OO±0.15fi was measured in accordance with JIS K-6723.

Example 1.2 The inside of a polymerization vessel with an internal volume of 2001 mm and equipped with a stirrer was replaced with nitrogen gas, and then 102 f of water and a saponification degree of 7 as a suspending agent were used.
4% polyvinyl alcohol (degree of polymerization 700) 0.12
1.0 parts by weight (based on 100 parts by weight of vinyl chloride monomer), 0.06 parts by weight of diisoptyryl peroxide as a catalyst, 2.
2'-azobis(2,4-dimethylvaleronitrile) 0
．． 03 parts by weight and 76.0 kg of vinyl chloride monomer [10
0 parts by weight] and while stirring, the first stage 1 shown in Table 1 was prepared.
The temperature was raised to a polymerization degree to advance polymerization, and when the polymerization rate reached 70%, the temperature was raised to the second stage polymerization degree shown in Table 1, and polymerization was further advanced. When the internal pressure of the first reactor reached 7.0 kti/dG, the polymerization was stopped, all unreacted monomers were recovered, and the obtained vinyl chloride polymer was dehydrated and dried.

Table 1 shows the degree of matte state, tensile strength, and tensile elongation of molded sheets produced by the above method for these polymers.

Example 3 A vinyl chloride polymer was obtained under the same conditions and operations as in Example 1, except that dicyclohexylcarbonyl peroxide was used as a catalyst instead of diisoptyryl peroxide.

Table 1 shows the degree of matte state, tensile strength and elongation of the molded sheet produced by the above method using this polymer.

Table 1 Comparative Example 1.2 The inside of a polymerization vessel with an internal volume of 2001 ml and equipped with a stirrer was replaced with nitrogen gas, and then 102 y of water and a saponification degree of 7 as a suspending agent were added.
4% polyvinyl alcohol (degree of polymerization 700) 0.12
parts by weight (based on 100 parts by weight of vinyl chloride monomer), 0% di(3-methoxybutyl)peroxybonate as a catalyst
．． 03 parts by weight, polyethylene glycol diacrylate 1
．． 0 parts by weight and 76.0 kg (100 kg) of vinyl chloride monomer
Parts by weight) were charged, the temperature was raised to the polymerization temperature shown in Table 2 while stirring, and the polymerization proceeded. When the internal pressure reached 5.5 kQ/dG, the polymerization was stopped and unreacted monomers were collected. The vinyl copolymer was dehydrated and dried.

Deaf product list-2 prepared by the above method for this polymer *1) Dissolve 0.21 of the polymer in 50 ml of nitrobenzene according to JIS K 6721, then pass through all the undissolved parts and determine the specific viscosity of the soluble parts. Measured and calculated.

*2) Polymer 0.5N'! z Polymerization degree of a polymer obtained by adding methyl alcohol to a THF solution from which undissolved matter was removed after being dissolved in THF and precipitated again (*1). Calculated from the specific viscosity of a polymer dissolved in nitrobenzene.

From Examples 1 to 3 and Comparative Examples 1 and 2, it is clear that since the polymers of the present invention have no gel content, they have extremely high tensile strength and large tensile elongation, although they have the same level of matteness.

Comparative Example 3.4 Polymerization was carried out at the temperature shown in Table 3, and when the internal pressure of the polymerization vessel reached 5.5 phantom/dG, the polymerization was stopped and unreacted monomers were collected. A vinyl chloride polymer was obtained in the same manner as in Example 1 except that the vinyl polymer was dehydrated and dried.

Table 3 shows the degree of matte state, tensile strength and tensile elongation of the molded sheet produced by the above method.

Table 3 From this table, it can be seen that unless the polymerization temperature is set in two stages, the material will not become matte at all.

Comparative Examples 5 to 7 The first stage polymerization degree, second stage polymerization rationality, and polymerization rate at the first stage polymerization degree are shown in Table 4 (when polymerized under the same conditions as Example 1 except for K). The results are shown in Table 4.

From Table 4, it can be seen that even if the polymerization temperature is set in two stages, the degree of matting will be insufficient unless the polymerization degree and ratio of the high polymerization variation and the low polymerization variation are appropriate.

Example 4, Comparative Examples 8 to 10 Polymers were obtained in the same manner as in Example 1, except that the catalyst shown in Table 5 and the parts by weight were used.

The results are shown in Table-5.

Table 5 *3) During the temperature rise from the first stage polymerization to the second stage polymerization, a drop in pressure started which only increased to 45°C.

*4) Similar to *3), the polymerization temperature did not increase up to 48°C.

From this table, it is clear that unless an appropriate catalyst is used, the degree of polymerization for the low degree of polymerization will not decrease, and that the degree of matting will be insufficient because the ratio of the high degree of polymerization to the low degree of polymerization is inappropriate. .

Example 5 A polymer was obtained in the same manner as in Example 1, except that 3 parts by weight of cetyl vinyl ether was added as a copolymerization additive. The results are shown in Table-6.

From the table below, it is clear that the present invention is also effective in copolymerizing vinyl chloride with a monomer copolymerizable with vinyl chloride.

that's all

Claims (1)

[Claims] (1) Vinyl chloride-based polymers are produced by charging vinyl chloride or a mixture of vinyl chloride and monomers that can be copolymerized with vinyl chloride into a polymerization vessel and carrying out aqueous suspension polymerization in the presence of a catalyst. In the method, diisoptyryl peroxide or dicyclohexyl carbonyl peroxide and a catalyst having a 10-hour half-life temperature of 50°C or higher are used together as a catalyst, and the polymerization reaction temperature is increased from 20 to 20 until the polymerization rate reaches 60 to 85%. After maintaining the temperature at 28°C, the polymerization temperature was increased to 50-70°C.
A method for producing vinyl chloride polymers characterized by raising the temperature to ℃.