JPS6220545A - Thermoplastic rubber composition - Google Patents

Abstract

PURPOSE:To provide the titled composition requiring no cure, low in compression set, high in weatherability, comprising chlorinated polyolefin containing specific amount of gel component, vinyl chloride resin, and plasticizer. CONSTITUTION:(A) A chlorinated polyolefin containing >=10 (pref. >=20) wt% of chloroform-insoluble gel component (e.g., prepared by intermolecular crosslinking of chlorinated polyolefin using a peroxide to form the gel component) and (B) vinyl chloride resin are mutually blended in a weight ratio A/B of 0.5/9.5-9/1 (pref. 1/9-8/2) followed by further blending (C) pref. 20-300pts. wt., based on 100pts.wt. of the component B, of at least one kind of plasticizer (e.g., di-2-ethylhexyl phthalate, di-n-octyl phthalate), thus obtaining the objective composition.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a thermoplastic rubber composition, and more specifically, a thermoplastic rubber composition that does not require vulcanization, has low compression set, and has excellent weather resistance. Regarding.

(Prior Art) A vinyl chloride resin composition containing a plasticizer, known as a soft vinyl chloride resin, has a soft rubber-like feel,
Compared to vulcanized rubber, moldability and cost are lower.

It has excellent weather resistance and coloring properties, and is used in a wide range of cavities. However, since the compression set is larger than that of vulcanized rubber, its use at high temperatures is limited. Therefore, a method has been adopted in which compression set is improved by adding cross-linked nitrile rubber to vinyl chloride resin containing gel content (Japanese Patent Application Laid-Open No. 58-215442.59-51933).
). However, although these methods can improve the compression set, the weather resistance deteriorates, which limits their applications.

Therefore, there is currently a strong need for a thermoplastic rubber that can be processed into thermoplastics, has compression set properties close to those of vulcanized rubber even without vulcanization, and has excellent weather resistance. be.

(Problems to be Solved by the Invention) In view of the above-mentioned circumstances, the inventors of the present invention have conducted extensive research to solve the above-mentioned problems, and have found that chlorinated polyolefin containing a specific amount of gel content, vinyl chloride resin, and plasticizer are essential. It was discovered that thermoplastic processing is possible, excellent weather resistance is achieved, and compression set is significantly improved without vulcanization by using a composition containing the components, and the present invention has been completed. It was.

(Means for Solving the Problems) Thus, according to the present invention, it is characterized by containing a chlorinated polyolefin having a gel content insoluble in chloroform of 10% by weight or more, a vinyl chloride resin, and a plasticizer. A thermoplastic rubber composition is provided.

Chlorination in the present invention? As the lyolefin, especially the chlorine ratio polyethylene, commercially available ordinary types can be used. This tetrachlorination? In order to make lyolefin contain a gel component, a method such as generating intermolecular crosslinks through a post-treatment reaction using 9-oxide or the like is adopted.

The gel content that is insoluble in chloroform is chloroform 100
m7! Add chlorinated polyolefin 0.2.9 to 3
This refers to the residue obtained by filtration through an 80 mesh wire mesh after day and night room temperature dissolution. The gel content must be at least 10 parts by weight, preferably 2 parts by weight.
0 fold f1 or more. If the r ratio is less than 10 times fk, compression set, which is one of the high temperature creep characteristics, will not be sufficiently improved, which is not desirable. Note that the upper limit of the gel content is not particularly limited, but in consideration of processability, it is preferably 98% or less.

Further, as the vinyl chloride resin, a homopolymer of vinyl chloride or a copolymer of a main proportion of vinyl chloride and a monomer copolymerizable with the vinyl chloride can be used. Here, other monomers that can be copolymerized with vinyl chloride include vinyl esters such as TE, vinyl acetate, vinyl stearate, olefins such as ethylene and fluoropylene, isobutyl vinyl ether, 2-
Vinyl ethers such as ethylhexyl vinyl ether and lauryl vinyl ether, and ethyl acrylate.

Acrylic acid esters such as n-butyl acrylate and 2-ethylhexyl acrylate, butyl maleate,
Examples include maleic acid esters such as maleic acid di(2-ethylhexy/L/).

Although the average degree of polymerization of the vinyl chloride resin is not particularly limited, it is usually 500 to 5.000, and a vinyl chloride resin containing a gel content insoluble in tetrahydrofuran may be used.

As the plasticizer, plasticizers commonly used for soft vinyl chloride resins can be used, such as so-2-ethylhexyl phthalate, di-n-octyl phthalate, diisodecyl 7-thaleate, dibutyl phthalate, and dibutyl phthalate. 7-talic acid ester: dioctyl adipate,
Linear dibasic acid ester such as dioctyl mono9cate: trimellitic acid ester 1. / IJ ester bulk polymer plasticizer Epoxy plasticizer such as epoxidized soybean oil and epoxidized linseed oil; Phosphate ester plasticizer such as triphenyl phosphate and tricresyl phosphate alone or in combination of two or more things are used.

The mixing ratio of chlorinated polyolefin and vinyl chloride resin is 0.
．． 5:9.5 to 9:1, preferably 1:9 to 8:
It is 2. If the mixing ratio is less than 0.5:9.5, a sufficient compression set improvement effect will not be exhibited, and if it exceeds 9:1, melt fluidity will decrease and processing methods will be restricted, which is not preferable.

The amount of plasticizer used in the present invention is appropriately selected depending on the hardness of the target product, but when considering soft rubber-like products, the amount of plasticizer used is 20 to 300 parts by weight per 100 parts by weight of vinyl chloride resin.
Parts by weight are preferred.

When producing the thermoplastic rubber composition in the present invention,
As in general vinyl chloride resin, stabilizers, lubricants,
Various additives such as fillers, antioxidants, ultraviolet absorbers, processing aids, blowing agents, pigments, flame retardants, and impact resistance aids can be added as necessary. Further, other polymers may be mixed.

(Effect of the invention) By molding the obtained composition using ordinary vinyl chloride resin processing methods such as extrusion molding, compression molding, calendar molding, blow molding, and injection molding, it is possible to mold the resulting composition with low compression set and excellent weather resistance. A molded product is obtained.

This molded product can be suitably used for automobile window seal materials, electric wire sheath materials, four-piece skins, etc., which require the same characteristics.

(Example) The present invention will be described in more detail with reference to Examples below. In addition, parts and parts in the examples are key 9 unless otherwise specified.
It has a weight base.

Example 1 Chlorinated polyethylene and vinyl chloride resin shown in Table 1,
and 100 parts of di-2-ethylhexyl phthalate, a barium-zinc composite stabilizer (RUP- manufactured by Adeka Argus)
14) Three parts were kneaded for 10 minutes with a heated roll at 150°C to obtain a sheet. These sheets were heated and pressed at 175° C. for 10 minutes to produce pressed test pieces of a predetermined thickness.

The compression set of this press test piece is JIS K-6301.
Compression set rate after 22 hours at 70°C under compression at 25 degrees (expressed as @). Weather resistance was evaluated by observing the discoloration of the test piece after 500 hours with a sunshine-type esalometer. .

The results are shown in Table 1.

Example 2 The same experiments and measurements as in Example 1 and Invention Example 1 were conducted except that the plasticizer shown in Table 2 was used. The results are shown in Table 2.

Table 2

Claims (1)

[Claims] A thermoplastic rubber composition comprising a chlorinated polyolefin having a gel content insoluble in chloroform of 10% by weight or more, a vinyl chloride resin, and a plasticizer.