JPH02191612A - Production of vinylidene chloride based resin - Google Patents

Abstract

PURPOSE:To obtain the title resin having good heat stability and workability and free from odor by polymerizing vinylidene chloride with a middle-chain alkyl acrylate at a specific ratio in the presence of an oil soluble polymerization initiator and high polymer dispersing agent in a water medium. CONSTITUTION:70-90 pts.wt. vinylidene chloride is polymerized with 30-2 pts.wt. 10-18C alkyl acrylate in the presence of an oil-soluble polymerization initiator (e.g. azobisvaleronitrile) and high polymer dispersing agent (e.g. methoxycellulose) in a water medium to provide the aimed resin. Furthermore, the polymerization initiator and high polymer dispersing agent are preferably used at amounts of 0.01-2.0 pts.wt. based on the 100 pts.wt. above-mentioned monomer mixture.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for producing vinylidene chloride resin, and more specifically, it relates to a method for producing vinylidene chloride resin, which has high polymerization productivity, good thermal stability and processability,
This invention relates to a method for producing odorless vinylidene chloride resin.

[Conventional technology and problems]

Vinylidene chloride resins are widely used in the packaging field because of their good gas barrier properties. General vinylidene chloride resin is a copolymer mainly composed of vinylidene chloride and vinyl chloride, but vinylidene chloride and vinyl chloride originally have low copolymerizability, so in order to obtain a copolymer with good physical properties, well-known polymerization According to this method, there are problems in that the polymerization time is very long and the polymerization productivity is low.

In order to improve polymerization productivity, there are methods such as increasing the amount of polymerization initiator and raising the polymerization temperature, but the copolymers obtained by these methods have poor thermal stability and low molecular weight, making it difficult to process them. There were drawbacks such as difficulty in molding and brittle molded products.

In general, the molecular weight is expressed as the specific viscosity vsp<concentration 0.4 g/
100-tetrahydrofuran, 30°C),
It is appropriate that ηsp be about 1.4 to 2.5 from the viewpoint of molding process and physical properties of the molded product. Therefore, in order to obtain a copolymer mainly composed of vinylidene chloride and vinyl chloride that has good thermal stability, processability, and physical properties of molded products, polymerization must be carried out at low temperatures for a long time. Generally, the temperature was set around 40°C and polymerization took about 50 hours (for example, Japanese Patent Publications No. 58-4933, No. 57-51850, No. 57
-9575, 55-18242).

On the other hand, a copolymer of vinylidene chloride and an alkyl acrylate having 1 to 8 carbon atoms can improve the above-mentioned drawbacks (for example, Japanese Patent Application No. 6O-289711), but the alkyl acrylate that remains unpolymerized in the copolymer There was a problem with the odor caused by

The present invention relates to a method for producing vinylidene chloride resins that overcomes these drawbacks.

[Means for solving problems]

The present invention contains 70 to 98 parts by weight of vinylidene chloride and 10 carbon atoms.
The method for producing vinylidene chloride resin is characterized by polymerizing 30 to 2 parts by weight of alkyl acrylate of No. 18 in an aqueous medium in the coexistence of an oil-soluble polymerization initiator and a polymer dispersant. .

The vinylidene chloride used in the present invention is obtained by adding 10% of vinylidene chloride to other vinyl monomers copolymerized with vinylidene chloride.
may contain up to less than 5 parts by weight per 0 parts by weight,
The other vinyl monomers mentioned here are known vinyl monomers other than vinyl chloride, such as alkyl vinyl ethers, acrylonitrile, styrene, alkyl vinyl esters, and the like. Vinylidene chloride is 70~
It is used in a range of 98 parts by weight. If it is less than 70 parts by weight, the gas barrier properties of the molded product will be poor, and if it exceeds 98 parts by weight, molding will become difficult.

The number of carbon atoms in the alkyl acrylate used in the present invention is 1
0 to 18, and these may be used alone or in combination. Alkyl acrylates having less than 10 carbon atoms are not preferred because the unpolymerized monomers that remain in the resin have a strong odor, and alkyl acrylates having more than 18 carbon atoms are not practical because of their high cost. Alkyl acrylate is used in a range of 30 to 2 parts by weight. If it is less than 2 parts by weight, molding becomes difficult, and if it exceeds 30 parts by weight, molding becomes difficult and the gas barrier properties of the molded product become low.

As the oil-soluble polymerization initiator used in the present invention, known azo initiators such as azobisvaleronitrile and azobisdimethoxyvaleronitrile, benzoyl peroxide,
lauroyl peroxide, diisopropyl peroxydicarbonate, di-5ec-butyl peroxydicarbonate, di-2-ethylexyl peroxydicarbonate, dimethoxyethyl peroxydicarbonate,
There are known organic peroxides such as tert-butyl peroxyneodecanate, which can be used alone or in combination. The amount used is vinylidene chloride and carbon number 10~
18 alkyl acrylate mixture (hereinafter referred to as monomer mixture) 0.01 to 2.011 per 100 parts by weight
In addition, the oil-soluble polymerization initiator may be added all at once at the initial stage of polymerization (or may be added in portions or continuously during polymerization, or in a combination of these methods; the combination type has higher polymerization productivity. Therefore, it is preferable.

Examples of polymeric dispersants used in the present invention include known cellulose derivatives such as methoxycellulose and ethoxycellulose, known water-soluble polymeric compounds such as partially saponified polyvinyl acetate, polyethylene oxide, and gelatin, which may be used alone or used in combination. Its usage is
The amount is preferably 0.01 to 2.0 parts by weight per 100 parts by weight of the monomer mixture.

Polymerization is carried out in the presence of the monomer mixture, an oil-soluble polymerization initiator, and a polymer dispersant at a monomer mixture/aqueous medium ratio of 173 to 3/3.
In the present invention, in order to adjust the degree of polymerization, known chain transfer agents such as 2-mercaptoethanol, dodecylmercaptan, and thioglycolic acid, phenolic antioxidants, and sulfur-containing There is no problem in using an appropriate amount of a known antioxidant such as a phosphorus-based antioxidant or a phosphorus-containing antioxidant, or a known epoxy compound such as epoxy soybean oil or epoxy linseed oil during polymerization.

The resin obtained in the present invention can be used for various molded articles, especially food packaging materials, by adding known additives such as stabilizers, plasticizers, and lubricants as required.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these.

Examples 1 to 8, Comparative Examples 1 to 12 9 kg of water, 4.5 g of methyl cellulose, 2N or 3 of a monomer consisting of vinylidene chloride, alkyl acrylate, and vinyl chloride were placed in a polymerization vessel with an internal volume of 201 equipped with a stirrer.
Total amount of seeds: 4.5 kg and total amount of these II bodies: 1
A predetermined amount of di-2-ethylhexyl peroxydicarbonate per 0.00 parts by weight was charged, polymerization was carried out at a predetermined temperature for a predetermined time, and the polymerization conversion rate was measured. Furthermore, the physical properties of the obtained resin were evaluated according to the following method. Results first
Shown in the table.

Measurement of specific viscosity <vsp>: The copolymer was dissolved in tetrahydrofuran, filtered, reprecipitated with methanol, dried, and dissolved again in tetrahydrofuran (concentration 0.4 g/
100val) at 30°C using an Oswald viscometer.
The specific viscosity was measured.

Evaluation of thermal stability: 3 parts by weight of epoxy soybean oil per 100 parts by weight of copolymer, ■! , ↑to' (trade name of ``Urban Fine Gemical ■'') is blended, and this is mixed with 150 parts by weight.
A sheet having a thickness of 1 mm was prepared by kneading for 3 minutes with a roll at 0.degree.

Odor evaluation: thermal stability i! ! Sheet 5 made with
0g in a sealed glass container with an internal volume of 300cc,
After standing at 0° C. for 24 hours, the lid of the glass container was opened, the odor was smelled, and the following judgments were made.

○=no odor
Ethylhexyl peroxydicarbonate *6 The vsp of a substance soluble in tetrahydrofuran was measured.

*7 Insoluble in tetrahydrofuran.

*8 The resin did not gel during roll kneading, and a sheet could not be produced.

*9 Resin adhered to the rolls when the rolls were crossed, making it impossible to collect samples.

From Table 1, it can be seen that in the Examples using stearyl acrylate, resins with high polymerization productivity, excellent processability (vsp) and thermal stability, and good odor can be obtained. In addition, when ethyl acrylate is used, it has a bad odor, and
When vinyl chloride is used, it is found that even if stearyl acrylate is used in combination with vinyl chloride, the polymerization productivity and thermal stability will be poor, and the vsp will be low.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a useful vinylidene chloride resin having high polymerization productivity, excellent thermal stability and processability, and no odor.

Claims (1)

[Claims] 1. Vinylidene chloride 70-98 parts by weight and carbon number 10-1
A method for producing a vinylidene chloride resin, which comprises polymerizing 30 to 2 parts by weight of the alkyl acrylate No. 8 in an aqueous medium in the coexistence of an oil-soluble polymerization initiator and a polymer dispersant.