JPS5946982B2 - Vinyl chloride resin composition - Google Patents

Description

[Detailed description of the invention] The present invention relates to a vinyl chloride resin composition.

Generally, a plasticizer is added to vinyl chloride resin as a means of imparting rubber-like elasticity to vinyl chloride resin.

However, such soft vinyl chloride resins tend to undergo plastic deformation, which limits their use in applications requiring rubber-like elasticity.

The present inventors focused on co-crosslinking of a vinyl chloride-based resin and a graft polymer having a butadiene polymer as a backbone in order to obtain a vinyl chloride-based resin composition free from the above-mentioned drawbacks. It is technically not easy to do so simply by blending a graft polymer with a crosslinking agent for vinyl chloride resin and/or a butadiene polymer as the backbone. However, co-crosslinking of the graft polymer having a vinyl chloride resin and a butadiene polymer as a backbone does not occur.

As a result of further intensive study, the present invention was completed. That is, the present invention is a vinyl chloride resin composition comprising a vinyl chloride copolymer having peroxide groups in its branches, a graft polymer having a butadiene polymer as a backbone, and a plasticizer. The molded product obtained by kneading and molding the product using an extruder or the like is a co-crosslinked product of polyvinyl chloride and a graft polymer with a butadiene polymer as the backbone, and has creep properties and heat resistance that are higher than those of general soft vinyl chloride. Significant improvement compared to other resins. Next, the composition of the present invention will be explained in detail.

First, the vinyl chloride copolymer in the composition of the present invention is an organic peroxide that can be copolymerized with vinyl chloride or a copolymerizable monomer mixture mainly composed of vinyl chloride (hereinafter referred to as vinyl chloride). (hereinafter referred to as copolymerizable peroxide) and vinyl chloride, and is a vinyl chloride copolymer (hereinafter referred to as PVC peroxide) having peroxide groups in its branches. be. Examples of monomers copolymerizable with vinyl chloride include vinyl monomers such as vinyl ether, acrylic ester, vinyl ketone, and vinylidene halide, or monoolefins. The copolymerizable peroxide used in the present invention is a compound having at least one copolymerizable double bond and a peroxide group in its molecule, and whose half-life is 1 minute at a temperature of 100°C or higher. Compounds having a temperature of 250° C. or lower are preferred, and specific examples thereof include t-butylperoxyallyl carbonate, t-butylperoxymethacrylate, and t-butylperoxysorbate.

The PVC peroxide in the present invention is obtained by combining the copolymerizable peroxide and vinyl chloride by a conventional polymerization method.
That is, it can be easily obtained by copolymerization using methods such as suspension polymerization, emulsion polymerization, and bulk polymerization. The composition of these copolymers preferably ranges from 99.9 to 80.0% by weight of vinyl chloride and from 0.1 to 20.0% by weight of copolymerizable peroxide.

If the copolymerizable peroxide is less than 0.1% by weight, the crosslinking density will decrease, and if it exceeds 20% by weight, the thermal stability of the product will be poor, which is not preferable. The graft polymer having a butadiene polymer as the main chain used in the present invention is not particularly limited as long as it is a graft polymer having a butadiene polymer as the main chain, and specific examples include acrylonitrile-butadiene-styrene copolymer ( ABS), methyl methacrylate-butadiene-styrene copolymer (MBS), and the like.

In addition, the amount of the graft polymer having a butadiene polymer as the backbone is 100 parts by weight of PVC peroxide.
It is preferably 0.1 to 50 parts by weight, and the optimum amount added can be changed as appropriate depending on the composition ratio of the copolymerizable peroxide in the PVC peroxide.

If the amount is less than 0.1 part by weight, it is difficult to improve the creep properties of the obtained molded article.

Moreover, if it exceeds 50 parts by weight, the cost tends to increase.

In the composition of the present invention, the plasticizer is added to provide a softened molded article, and the amount added varies depending on the intended use of the molded article.

It is preferably 5 to 200 parts by weight per 100 parts by weight of PVC peroxide. If it is less than 5 parts by weight, processing will be difficult and the resulting molded product will have low elasticity.

On the other hand, if it exceeds 200 parts by weight, dry-up will not occur, which is undesirable for use. Examples of such plasticizers include dibutyl phthalate, dioctyl phthalate, butylbenzyl phthalate, dioctyl adipate, dioctyl sebacate, and the like. In addition to the above-mentioned components, the composition of the present invention may optionally include a heat stabilizer, a filler, a blowing agent,
Flame retardants, pigments and processing aids may be added.

The present invention will be explained in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

In addition, the gel fraction in the example is 2% in tetrahydrofuran at 70°C.
When immersed for 4 hours, it is the weight % of the insoluble resin content relative to the resin content before immersion.

The compression set was measured in accordance with JISK-6301, and the measurement conditions were 70° C. x 22 hours, and the compression ratio was 25%. Example 1 99 parts by weight of vinyl chloride (hereinafter referred to as "parts") and 1 part of t-butyl peroxyaryl carbonate [Peroma-AC manufactured by Nippon Oil & Fats Co., Ltd.] were polymerized at 55°C by a conventional suspension polymerization method to form PVC peroxide. 80 parts (P=1000) were obtained.

Next, per 100 parts of this PVC peroxide, 80 parts of dioctyl phthalate, acrylonitrile-butane diene-styrene copolymer (ABS) [JS manufactured by Japan Synthetic Rubber Co., Ltd.
RABS6O] and 5 parts of tribasic lead sulfate (thermal stabilizer) were added and kneaded for 5 minutes with a roll at 160°C to form pellets.

The pellets were extrusion-molded (using a 40φ extruder manufactured by Nippon Steel Corporation) to form a sheet with a thickness of 12.7 mm, and samples were taken out for measurement of gel fraction and compression set. As a result, the gel fraction was 70% and the compression set was 50%. Example 2 99 parts of vinyl chloride and 1 part of t-butyl peroxyallyl carbonate were polymerized at 45°C by a normal suspension polymerization method to obtain P.
80 parts of VC peroxide (P=1700) were obtained.

Next, per 100 parts of this PVC peroxide, 80 parts of dioctyl phthalate, methyl methacrylate-butadiene-styrene copolymer (MBS) [J
SRMBS67] and 5 parts of tribasic lead sulfate were added and tested in the same manner as in Example 1.

As a result, the gel fraction was 50% and the compression set was 50%.

Comparative Example 1 In Example 1, ordinary straight PVC [Aron TS-1100, manufactured by Toagosei Chemical Industry Co., Ltd.] was used instead of PVC peroxide. P=1050], and the same test was conducted except that ABS was not added.

As a result, the gel fraction was 0% and the compression set was 75%. Comparative Example 2 The same test as in Example 1 was conducted except that ordinary straight PVC (Aron TS-1100, manufactured by Toagosei Kagaku Kogyo Co., Ltd., P=1050) was used instead of PVC peroxide.

As a result, the gel fraction was 0% and the compression set was 75%. Comparative Example 3 In Example 1, the same composition was used except that the plasticizer (dioctyl phthalate) was not mixed, and the mixture was kneaded at 180°C, but sufficient kneading was not possible and a sheet could not be produced.

Claims (1)

[Claims] 1. A vinyl chloride resin composition comprising a vinyl chloride copolymer having peroxide groups in its branches, a graft polymer having a butadiene polymer as a backbone, and a plasticizer.