JPS6254334B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a thermoplastic resin composition, and more particularly to a method for producing a soft thermoplastic resin composition with improved oil resistance, low-temperature flexibility, heat resistance, processability, and transparency. Vinyl chloride resin can be produced in large quantities at low cost and has excellent physical and chemical properties, so
It is used for various purposes. The soft vinyl chloride resin is blended with a plasticizer such as dioctyl phthalate or dioctyl adipate, giving it flexibility and making it suitable for uses such as packaging materials. However, for products containing a large amount of plasticizer, there is a noticeable drop in oil resistance due to the elution of the plasticizer in the oil resistance test, and a noticeable drop in heat resistance due to the volatilization of the plasticizer in the heat resistance test. . In order to eliminate the above disadvantages of soft vinyl chloride resin, for example, chlorinated polyethylene can be mixed with vinyl chloride resin, ethylene-vinyl acetate copolymer can be mixed with vinyl chloride resin, ethylene-vinyl acetate copolymer Graft copolymerization of vinyl chloride has been adopted for coalescence. However, in none of these, the properties such as low temperature flexibility and transparency were not sufficiently improved. It has also been proposed to mix thermoplastic polyurethane with vinyl chloride resin. However, this method resulted in too strong adhesion during processing, and it was not possible to obtain a molded product with a smooth surface. The present inventors aimed to eliminate the drawbacks of conventional vinyl chloride resin compositions, and aimed to improve oil resistance, low temperature flexibility, heat resistance,
The object of the present invention is to provide a method for producing a soft thermoplastic resin composition with improved processability and transparency. The gist of the present invention is to combine 15 to 60 parts by weight of ethylene-vinyl acetate copolymer and 10 to 40 parts by weight of thermoplastic polyurethane.
A thermoplastic resin composition characterized by dissolving 30 to 75 parts by weight of vinyl chloride monomer in 30 to 75 parts by weight of vinyl chloride monomer, and then graft polymerizing the vinyl chloride monomer to the ethylene-vinyl acetate copolymer and thermoplastic polyurethane. It lies in the method of manufacturing a product. Next, the method for producing the thermoplastic resin composition of the present invention will be explained in more detail. Ethylene-vinyl acetate copolymer (hereinafter simply referred to as
The amount of copolymerized vinyl acetate in EVA (referred to as EVA) is preferably 20 to 70% by weight. The amount of copolymerization of vinyl acetate in EVA is 20
If it is less than 70% by weight, transparency and oil resistance will decrease, and if it is more than 70% by weight, thermal flexibility will tend to decrease. Preferably, it is in portions. Also, the amount of copolymerized ethylene in EVA is
A preferable range is 80 to 30% by weight. The amount of EVA used is 15 to 60 parts by weight. This is because if the amount of EVA used is less than 15 parts by weight, the product will have poor low temperature flexibility, and if it is more than 60 parts by weight, the mechanical strength will tend to decrease. EVA may be produced by any of emulsion polymerization, high pressure polymerization, and suspension polymerization. In the production of EVA, in addition to ethylene and vinyl acetate, other monomers such as acrylic ester, methacrylic ester, and versatile ester are used in combination to the extent that they do not impair the properties of EVA.
They can also be partially copolymerized. As the thermoplastic polyurethane, those in which the polyol part is of the adipate type, polyether type, caprolactone type, etc. are suitable for use. In order to make the particle size distribution of the graft polymer uniform, it is preferable to use an adipate type. The amount of thermoplastic polyurethane used is 10 to 40 parts by weight. If the amount of thermoplastic polyurethane used is less than 10 parts by weight, low temperature flexibility will not be sufficiently improved, and if it is more than 40 parts by weight, mechanical strength will decrease and processability will deteriorate. It is from. EVA 15-60 parts by weight and thermoplastic polyurethane
10 to 40 parts by weight of the mixture, 30 to 40 parts by weight of vinyl chloride monomer
Add 75 parts by weight to dissolve EVA and thermoplastic polyurethane in vinyl chloride monomer, then
Graft polymerization of vinyl chloride monomer onto EVA and thermoplastic polyurethane. In this case,
Other monomers copolymerizable with vinyl chloride, such as α-olefins such as ethylene and propylene, vinyl esters such as vinyl acetate and vinyl stearate,
Acrylic esters such as 2-ethylhexyl acrylate and η-octyl acrylate, versatile esters, vinyl ethers, methacrylic esters, acrylonitrile, etc. are used in combination, and these monomers are chlorinated to the extent that the properties of the graft polymer are not impaired. It may also be graft polymerized together with vinyl. When these monomers are used, a graft polymer is obtained in which these monomers are randomly polymerized together with vinyl chloride. After dissolving EVA and thermoplastic polyurethane in vinyl chloride monomer, graft polymerization may be carried out by any method such as suspension polymerization, emulsion polymerization, solution polymerization, or bulk polymerization. Suspension polymerization is most suitable since a composition with a particle size can be obtained. Examples of polymerization initiators used in graft polymerization include organic peroxides such as benzoyl peroxide and 2-ethylhexyl peroxydicarbonate, and azo initiators such as azobisisobutyronitrile and azobisvaleronitrile. , ammonium peroxide, potassium peroxide, and other water-soluble peroxides. In addition, dispersants and emulsifiers such as cellulose-based dispersants such as ethyl cellulose, carboxymethyl cellulose, and hydroxypropyl cellulose, organic dispersants such as polyvinyl alcohol, gelatin, and polyvinylpyrrolidone, anionic surfactants such as sodium alkylbenzenesulfonate, and Nonionic surfactants such as oxyethylene alkyl ethers are used. Also, sodium hydroxide, calcium carbonate, etc. may be used as a pH regulator, and η-dodecylmercaptan, η-octylmercaptan, etc. may be used as a polymerization degree regulator. Furthermore, antioxidants, heat stabilizers, etc. can also be added. By adding vinyl chloride monomer to EVA and thermoplastic polyurethane and dissolving it, heating to about 50 to 70°C to react, and graft polymerizing the vinyl chloride monomer to EVA and thermoplastic polyurethane, respectively. A homogenized composition consisting of EVA graft-polymerized with vinyl chloride and thermoplastic polyurethane graft-polymerized with vinyl chloride is obtained. Such a composition is separated from the reaction solution by sedimentation, dehydration, and drying. According to the present invention, the homogenized composition is composed of EVA graft-polymerized with vinyl chloride and thermoplastic polyurethane graft-polymerized with vinyl chloride, and has oil resistance and low-temperature flexibility. A thermoplastic resin composition that is flexible, has good properties in terms of properties, heat resistance, processability, and transparency can be obtained. Such thermoplastic resin compositions are suitable for use as packaging materials, for example. The method of the present invention will be explained below using examples. The performance evaluation shown in Table 1 shows the results as follows. Transparency: Judgment by visual observation. Workability: Judged by the adhesion to the roll surface during roll kneading at 150℃. Tensile strength: Measured value in accordance with ASTM D-638 (Kg/cm ² ) Elongation rate: Measured value of elongation until tensile breakage (%) Oil resistance: In accordance with JIS C-3005, No. 2 insulating oil at 70°C Measured values of residual tensile strength and residual elongation (%) after 4-hour immersion in Measured value of weight loss (%) Low-temperature flexibility: Temperature measured by Kratschberg flexibility temperature measuring device (°C) Shore hardness: Hardness at -20°C by type D Example 1 EVA obtained by emulsion polymerization Polymerization component: 60% by weight) 40 parts by weight, 30 parts by weight of thermoplastic polyurethane with an adipate polyol moiety, 250 parts by weight of ion-exchanged water, 1 part by weight of partially saponified polyvinyl alcohol, 1.5 parts by weight of methylcellulose.
Part by weight and 0.1 part by weight of lauroyl peroxide were placed in an autoclave equipped with a stirrer, and after removing oxygen in the autoclave, vinyl chloride monomer was added.
100 parts by weight was charged. The mixture was kept at 20°C and stirred for 2 hours to dissolve EVA and thermoplastic polyurethane in the vinyl chloride monomer. Next, the temperature was raised to 65°C, and the graft polymerization reaction was carried out over 6 hours while stirring.
The reaction was stopped when 80% by weight of the vinyl chloride monomer was polymerized, and unreacted vinyl chloride monomer was removed. The obtained graft polymer was taken out from the autoclave and subjected to dehydration and drying treatments. The composition thus obtained consists of a homogenized composition of EVA graft-polymerized with vinyl chloride and thermoplastic polyurethane graft-polymerized with vinyl chloride.
26% by weight, thermoplastic polyurethane 20% by weight,
Vinyl chloride was 54% by weight. The properties were measured using 100 parts by weight of this composition to which 2.0 parts by weight of a heat stabilizer and 0.3 parts by weight of a lubricant were added. The results are shown in the column of Example 1 in Table 1. Example 2 In Example 1, obtained by emulsion polymerization
Instead of 40 parts by weight of EVA, EVA obtained by high-pressure polymerization (copolymerized content of vinyl acetate: 40% by weight)
The same operation as in Example 1 was carried out except that 28 parts by weight was used, and a homogenized composition of EVA graft-polymerized with vinyl chloride and thermoplastic polyurethane graft-polymerized with vinyl chloride was prepared. Obtained. The respective copolymerization components were 20% by weight of EVA, 22% by weight of thermoplastic polyurethane, and 58% of vinyl chloride. The properties were measured using 100 parts by weight of this composition to which 2.0 parts by weight of a heat stabilizer and 0.3 parts by weight of a lubricant were added as in Example 1. The results are shown in the column of Example 2 in Table 1. Comparative Example 1 26 parts by weight of EVA obtained by emulsion polymerization (copolymerized content of vinyl acetate: 60% by weight), 30 parts by weight of thermoplastic polyurethane with an adipate type polyol part, 54 parts by weight of vinyl chloride resin with an average degree of polymerization of 800. ,
The results of measuring the properties using a composition consisting of 2.0 parts by weight of a heat stabilizer and 0.3 parts by weight of a lubricant are shown in the column of Comparative Example 1 in Table 1.

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Claims (1)

[Claims] 1. 15 to 60 parts by weight of ethylene-vinyl acetate copolymer and 10 to 40 parts by weight of thermoplastic polyurethane are dissolved in 30 to 75 parts by weight of vinyl chloride monomer, and then the ethylene-vinyl acetate copolymer is dissolved in 30 to 75 parts by weight of vinyl chloride monomer. A method for producing a thermoplastic resin composition, comprising graft polymerizing a vinyl chloride monomer to a copolymer and a thermoplastic polyurethane. 2. The method for producing a thermoplastic resin composition according to claim 1, wherein the copolymerized content of vinyl acetate in the ethylene-vinyl acetate copolymer is 20 to 70% by weight.