JPH0446911A - Production of vinyl chloride copolymer - Google Patents

Abstract

PURPOSE:To produce a vinyl chloride copolymer having a high bulk specific gravity and improved particle diameter distribution and heat resistance by adding a specified epoxidized linear alkylvinyl monomer to a monomer mixture based on vinyl chloride and suspension-polymerizing the resulting mixture in an aqueous medium. CONSTITUTION:0.01-2pts.wt. epoxy-terminated linear alkyl vinyl monomer of the formula (wherein (n) is 2-20) is added to 100pts.wt. mixture of 50-100wt.% vinyl chloride with 50-0wt.% vinyl monomer, and the resulting mixture is suspension-polymerized in an aqueous medium in the presence of a dispersing aid and a polymerization initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a high quality vinyl chloride copolymer with high productivity and improved thermal stability.

(Conventional technology) Conventionally, vinyl chloride resin products are inexpensive, have excellent mechanical properties, chemical resistance, weather resistance, transparency, etc., and can be made into products of any hardness from hard to soft by adding various plasticizers. Because of this, it is used in a wide range of fields.

However, due to poor thermal stability during molding, the resulting products often have problems such as decreased mechanical properties and coloration. To prevent this, stabilizers made of various metal compounds are added. For medical and food packaging materials, a method is adopted in which Ca-Zn stabilizers are added to meet the demands of non-toxic, odorless, non-colored, and low-cost materials. , it was still not perfect.

(Problem to be Solved by the Invention) In order to solve this problem, a method was proposed in which vinyl chloride was polymerized in the presence of an epoxy compound such as epoxyalkyl acrylate or allyl glycidyl ether (Japanese Patent Application Laid-Open No. 54-63188 and 58-2311
However, the former has a low bulk specific gravity that reduces production during processing, and the latter has a wide particle size distribution that impairs gelation rate characteristics during processing and reduces productivity. A common problem with these methods is that the polymerization time is prolonged, impairing productivity.

(Means for Solving the Problem) In order to solve this problem, the present inventors have conducted intensive research and found that a linear alkyl vinyl monomer having an epoxy group at the end is copolymerized with a vinyl chloride monomer. For example, they have discovered that a high-quality vinyl chloride copolymer with good thermal stability can be obtained with high productivity, and have completed the present invention.

That is, the method for producing a vinyl chloride copolymer according to the present invention involves suspending and polymerizing a vinyl chloride monomer or a mixture of vinyl monomers mainly composed of vinyl chloride in an aqueous medium. Per 100 parts by weight of the monomer or mixture thereof, 0.01% of the linear alkyl vinyl monomer having an epoxy group at the end represented by the general formula: %formula% (n in the formula is an integer of 2 to 20) The gist is to add up to 2 parts by weight.

To explain this, in the linear alkyl vinyl monomer having an epoxy group at the terminal represented by the above general formula used in the present invention, n in the formula is 2 to 20, preferably 2 to 14. , which includes 1,2-epoxyhexene-5,1,
Examples include 2-epoxyhebutene-6,1°2-epoxyoctene-7,1,2-epoxydecene-9.

Note that if n exceeds 20, the effect of improving thermal stability will be weakened, which is not preferable.

This monomer is 0.01 to 2 parts by weight, preferably 0.04 to 1.5 parts by weight, per 100 parts by weight of vinyl chloride monomer or a mixture of vinyl monomers mainly composed of vinyl chloride. part, more preferably 0.05 to 1 part by weight. If the amount added is less than 0.011 parts by weight, the effect of improving thermal stability cannot be obtained, and if it exceeds 2 parts by weight, the polymerization time becomes longer and productivity deteriorates, resulting in a vinyl chloride polymer of the desired molecular urine. becomes difficult to obtain.

The monomer may be added to the polymerization system before the start of polymerization, immediately after the start of polymerization, or during polymerization, and the monomer may be added all at once or in several parts.

In this polymerization, in addition to vinyl chloride monomer alone, a mixture (vinyl chloride of 500 parts by weight or more) of a vinyl monomer (comonomer) that can be copolymerized with vinyl chloride as a main component may be used. Examples of the comonomer include vinyl esters such as vinyl acetate and vinyl propionate; acrylic esters or methacrylic esters such as methyl acrylate and ethyl acrylate; olefins such as ethylene and propylene; vinyl ethers such as lauryl vinyl ether and isobutyl vinyl ether; Examples include maleic anhydride; acrylonitrile; styrene; vinylidene chloride; and other monomers copolymerizable with vinyl chloride.

The suspension polymerization in an aqueous medium according to the invention using these monomers can be carried out using dispersing aids commonly used in the polymerization of vinyl chloride in an aqueous medium, such as methylcellulose, ethylcellulose, hydroxyethylcellulose, Water-soluble cellulose ethers such as hydroxypropylcellulose and hydroxypropylmethylcellulose; partially saponified polyvinyl alcohol; acrylic acid polymers; water-soluble polymers such as gelatin; sorbitan monolaurate.

Oil-soluble emulsifiers such as sorbitan triolate, sorbitan monostearate, glycerin tristearate, ethylene oxide propylene oxide block copolymers;
Water-soluble emulsifiers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerol oleate, sodium laurate; calcium carbonate, calcium phosphate, sodium dodecylbenzenesulfonate, etc.; these can be used alone or in combination of two or more used in

The polymerization initiator used in this polymerization may also be one that has been conventionally used in vinyl chloride polymerization, such as diisopropyl peroxydicarbonate, di-2-
Percarbonate compounds such as ethylhexyl peroxydicarbonate, jetoxyethyl peroxydicarbonate; t-butylperoxyneodecanate, t-
Perester compounds such as butyl peroxypiparate, t-hexylperoxypivalate, α-cumylperoxyneodecanate; acetylcyclohexylsulfonyl peroxide, 2,4.4-trimethylpentyl-2-peroxyphenoxy Acetate, 3.5.5-
)-limethylhexanoyl peroxide; oil-soluble catalysts such as azo compounds such as azobis-2,4-dimethylvaleronitrile and azobis(4-methoxy-2,4-dimethylvaleronitrile); These can be used alone or in combination of two or more.

Moreover, water-soluble catalysts such as potassium persulfate, ammonium persulfate, hydrogen peroxide, and cumene hydroperoxide can also be used in combination with these oil-soluble catalysts.

The other conditions for this polymerization and the method of charging the aqueous medium, vinyl chloride monomer, other comonomers, dispersion aids, polymerization initiator, etc. to the polymerization vessel can be carried out in the same manner as conventional methods. The polymerization conditions such as the charging ratio and polymerization temperature may also be the same.

Furthermore, this polymerization system may contain polymerization modifiers, chain transfer agents, pH adjusters, gelling improvers, antistatic agents, crosslinking agents, stabilizers, and fillers that are appropriately used in vinyl chloride polymerization. It is also optional to add agents, antioxidants, buffers, scale inhibitors, and the like.

(Examples) Hereinafter, specific aspects of the present invention will be explained using Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 Deionized water and 280 g of 500-1 partially saponified polyvinyl alcohol were charged into a stainless steel autoclave with an internal volume of 1000 Q and equipped with a stirrer and a jacket. After degassing the inside of the vessel, 350 kg of vinyl chloride monomer and 1. 3.5 kg of 2-epoxyhexene-5 and 350 g of di-2-ethylhexyl peroxydicarbonate were charged, and while stirring, hot water was passed through the jacket and the temperature was raised to 57°C to initiate polymerization.

When the internal pressure of the polymerization vessel decreased to 5.5 kg/aJG, the reaction was stopped, unreacted single cells were collected, and the polymer slurry was taken out of the vessel and dehydrated and dried to produce the vinyl chloride polymer according to the present invention. I got it. The polymerization time at this time was 6.5 hours.

Example 2 Polymerization was carried out in the same manner as in Example 1 except that the amount of 1,2-epoxyhexene-5 added was changed to 1.75 kg, and the required time was 5 hours.

Example 3 Polymerization was carried out in the same manner as in Example 1 except that the amount of 1,2-epoxyhexene-5 added was 7 kg, and the required time was 10 hours.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that 1,2-epoxyhexene-5 was not added, and the required time was 3 hours.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that the amount of 1,2-epoxyhexene-5 added was 8.75 kg, and the required time was 18 hours.

Comparative Example 3 Polymerization was carried out in the same manner as in Example 1 except that the same amount of allyl glycidyl ether was used instead of 1,2-epoxyhexene-5, and the required time was 18 hours.

Comparative Example 4 Polymerization was carried out in the same manner as in Example 1 except that epoxyalkyl acrylate was used instead of 1,2-epoxyhexene-5, and the required time was 15 hours.

Comparative Example 5 1% by weight of 1,2-epoxyhexene-5 was added and mixed to the polymer obtained in Comparative Example 1, and the thermal stability was measured.

The bulk specific gravity, particle size distribution, and thermal stability of the vinyl chloride polymers obtained in each of the above Examples and Comparative Examples 1 to 4 were measured using the following methods, and the results are shown in the attached table along with Comparative Example 5. It was shown to.

Bulk ratio weight: According to JIS K-6721.

Granular charcoal distribution: Measured using a sieve specified in JIS Z-8801.

Thermal stability test: Vinyl chloride copolymer lOO parts by weight DOP
5Q uCa-Zn stabilizer 1.5 Lubricant
0.5〃Epoxidized soybean oil
8 phosphite chelator-1 was blended and kneaded for 5 minutes at 160°C using a 6-inch roll to create a sheet with a thickness of 0.8 wwn, which was cut and placed in a gear oven at 190°C. A thermal deterioration test was conducted to measure the time (minutes) until blackening.

(Effects of the Invention) According to the present invention, a high-quality vinyl chloride copolymer with high bulk specific gravity, improved particle size distribution, and good thermal stability can be obtained with high productivity in a short polymerization time.

Claims (1)

[Scope of Claims] 1. When a vinyl chloride monomer or a mixture of vinyl monomers mainly composed of vinyl chloride is subjected to suspension polymerization in an aqueous medium, 100% by weight of the monomer or the mixture thereof Per part, general formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (n in the formula is an integer of 2 to 20) A linear alkyl vinyl monomer having an epoxy group at the end expressed as 0.01~ A method for producing a vinyl chloride copolymer, which comprises adding 2 parts by weight.