JP2529509B2 - Vinyl chloride resin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl chloride resin composition excellent in moisture absorption resistance, impact resistance and secondary moldability.

[0002]

2. Description of the Related Art Generally, vinyl chloride resins are widely used as molding materials for various articles because they have good chemical and physical properties. However, impact resistance and vacuum molding, pressure molding, etc. There is a drawback that it is inferior in formability.

As a means for coping with such a difficulty, an acrylic rubber polymer or M is used to improve impact resistance.
It is conceivable to add a modifier composed of a BS-based resin or a processing aid composed of a polymer mainly containing methyl methacrylate in order to improve secondary processability. Various concrete vinyl chloride resin compositions containing agents have been proposed in the past.

Further, as a particularly excellent impact modifier,
A composite rubber having a structure in which a polyorganosiloxane rubber component and a polyalkyl (meth) acrylate rubber component are inseparably entangled with each other and graft-polymerized with a vinyl monomer has been proposed (JP-A-1- 2799
No. 54).

[0005]

However, although the impact resistance and secondary moldability of vinyl chloride resins are improved to some extent by the above-mentioned modifiers and processing aids, the use of the modifiers results in vinyl chloride. The hygroscopicity of the system resin increases, and the moisture in the resin is vaporized by heat during secondary molding such as vacuum molding or pressure molding, which causes a new problem that unevenness due to foaming occurs on the surface of the molded product.

As a means for avoiding such a problem due to moisture absorption, it is conceivable to carry out preliminary drying before the secondary molding, but the equipment cost for the drying is high and it takes a long time for the drying. The molding efficiency will deteriorate.

In view of the above circumstances, the present invention is a chloride which has good impact resistance and secondary moldability, and is excellent in moisture absorption resistance, so that a high quality molded product can be efficiently manufactured at low cost. It is intended to provide a vinyl resin composition.

[0008]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies in order to achieve the above-mentioned object and, as a result, have found that a silicone rubber similar to the above-mentioned impact modifier for vinyl chloride resin can be used. A graft copolymer in which a vinyl monomer was graft-polymerized to a composite rubber of a component and an acrylic rubber component, and a (meth) acrylic copolymer containing methyl methacrylate were blended in extremely limited ranges, respectively. When the composition is used, the moisture absorption resistance is remarkably improved and the secondary moldability is also improved. The secondary molding does not require pretreatment such as preliminary drying, and is of high quality and excellent in impact resistance. The present invention has been completed by finding out that it can be efficiently obtained at low cost.

That is, the present invention has a structure in which (a) 100 parts by weight of a vinyl chloride resin, (b) a polyorganosiloxane rubber component and a polyalkyl (meth) acrylate rubber component are inseparably entangled with each other. 5.0-6.0 parts by weight of a graft copolymer obtained by graft-polymerizing one or more vinyl-based monomers to the composite rubber having
(C) A vinyl chloride resin composition obtained by blending 2.5 to 8 parts by weight of a copolymer of methyl methacrylate, another alkyl methacrylate, and another monomer copolymerizable therewith. .

[0010]

[Detailed configuration and operation of the invention]

The vinyl chloride resin as the component (a) can be used without particular limitation as long as it has vinyl chloride as the main component of the monomer, but a vinyl chloride homopolymer having an average degree of polymerization of 700 to 1300 is particularly preferable. It is suitable.

The graft copolymer of component (b) is a composite rubber of a polyorganosiloxane rubber component and a polyalkyl (meth) acrylate rubber component as described above, which is obtained by graft-polymerizing a vinyl monomer. It has a function of imparting excellent impact resistance to a molded product obtained by using the vinyl chloride resin composition containing the same. Then, the blending amount is 5.0 to 100 parts by weight of the vinyl chloride resin.
It is necessary to set it in a very limited range of 6.0 parts by weight, more preferably 5.2 to 5.8 parts by weight. That is, when the blending amount is more than 6.0 parts by weight, the hygroscopicity of the vinyl chloride resin composition becomes high and foaming occurs due to evaporation of water during secondary molding, while less than 5.0 parts by weight is sufficient. Impact resistance cannot be obtained.

Here, the polyorganosiloxane rubber component in the above composite rubber is a cyclic organosiloxane having about 3 to 6 membered rings, a trifunctional or tetrafunctional silane crosslinking agent, and if necessary, a graft crossing agent. It is prepared by carrying out emulsion polymerization using. The latex of the polyorganosiloxane rubber component thus obtained is neutralized with an aqueous alkali solution, and then an alkyl (meth) acrylate, an alkylene glycol dimethacrylate-based crosslinking agent and a graft crossing agent are added to act as a radical polymerization initiator. By emulsion polymerization, polyalkyl (meth) is formed in such a way that the crosslinked networks of the polyorganosiloxane rubber component are entangled with each other.
A crosslinked network of the acrylate rubber component is formed, and a latex of a composite rubber in which both rubber components are substantially inseparable is obtained. The obtained composite rubber has the property of being graft-copolymerizable with the vinyl-based monomer. By adding the vinyl-based monomer to the latex after the polymerization and graft-copolymerizing the component (b), The graft copolymer of is synthesized.

The ratio of the polyorganosiloxane rubber component to the alkyl (meth) acrylate rubber component in the above composite rubber is 1/99 to 99 / in terms of the former / the latter weight ratio.
1, more preferably in the range of 10/90 to 90/10. The amount of the vinyl-based monomer to be graft-polymerized on the composite rubber is 5 to 70% by weight, more preferably 10 to 60% by weight based on the graft copolymerization after synthesis.
It is preferable to set it in the range of occupying weight%.

Examples of vinyl monomers to be graft-polymerized on the composite rubber include aromatic alkenyl compounds such as styrene, α-methylstyrene and vinyltoluene, methacrylic acid esters such as methylmethacrylate and 2-ethylhexylmethacrylate, methylacrylate and ethyl. Examples thereof include acrylic acid esters such as acrylate and butyl acrylate, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, and these may be used in combination of two or more kinds.

The component (b) graft copolymer has the same constitution as the impact modifier disclosed in the above-mentioned JP-A-1-279954 and is used for its synthesis. Specific examples and usage amounts of the polymerization material, the cross-linking agent, the graft crossing agent, the polymerization initiator and the like, and specific polymerization conditions are also as described in the publication. However, in this invention,
By blending the graft copolymer of the component (b) with the vinyl chloride resin of the component (a) in an extremely limited range as described above, sufficient impact resistance is imparted and moisture absorption is remarkably increased. It has been successfully reduced.

The component (c) mainly has a function as a processing aid for improving the secondary moldability of the vinyl chloride resin composition, and as described above, methyl methacrylate and other alkyl methacrylates and their co-products are used. It is composed of a copolymer with another polymerizable monomer and is not particularly limited, but one having an average molecular weight of about 3,000,000 to 5,000,000 is preferable. Then, the blending amount of the vinyl chloride resin 10
It is necessary to set it in the range of 2.5 to 8.0 parts by weight, more preferably 3.0 to 6.0 parts by weight with respect to 0 parts by weight,
If it is less than 2.5 parts by weight, sufficient secondary moldability cannot be obtained, and if it exceeds 8.0 parts by weight, the impact resistance of the molded product becomes insufficient.

Examples of the alkyl (meth) acrylate other than methyl methacrylate used in the above copolymer include ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate and the like. In addition, examples of other monomers copolymerizable with these methacrylates include styrene, butadiene, acrylonitrile, and divinylbenzene, and two or more kinds may be used in combination. Therefore, the usage ratio of these monomers is 50 to 100% by weight of methyl methacrylate, 0 to 50% by weight of other alkyl methacrylate, and 0 to 30% by weight of other monomer copolymerizable therewith. Good to do.

[0018]

【Example】

Examples 1 to 3 Vinyl chloride resin having an average degree of polymerization of 800 as component (a) (Kanevinyl S-100, trade name, manufactured by Kanegafuchi Chemical Industry Co., Ltd.)
8) As a component (b), a graft copolymer of 90% by weight of a composite rubber having a polyorganosiloxane rubber component / alkyl (meth) acrylate rubber component weight ratio of 1/18 and 10% by weight of methyl methacrylate (Mitsubishi Rayon Co., Ltd. Manufactured by METABLENE S-2001), and a copolymer of methyl methacrylate-isobutyl acrylate-butadiene in a weight ratio of 85: 10: 5 (METABRENE P-530A manufactured by Mitsubishi Rayon Co., Ltd.) as the component (c). Were mixed in the proportions shown in Table 1 below, and mixed with a high-speed mixer to prepare a vinyl chloride resin composition.
Then, this composition was supplied to an extruder and kneaded with a screw in a cylinder, and extrusion-molded under heating at 150 to 170 ° C. to produce a vinyl chloride resin sheet having a thickness of 3 mm.

Comparative Examples 1 to 6 Example 1 was repeated except that the same components as in Examples 1 to 3 were used as the components (a) to (c) and the compounding ratios thereof were changed to the ratios shown in Table 1 below. A vinyl chloride resin sheet having a thickness of 3 mm was produced by extrusion molding in the same manner as in the above-mentioned procedure.

Comparative Examples 7 and 8 The same components as in Examples 1 to 3 were used as the components (a) and (c), and the acrylic rubber type modifier (Kanebuchi) was used as the component (d) instead of the component (b). A vinyl chloride resin having a thickness of 3 mm was extruded in the same manner as in Examples 1 to 3 except that Kaneace FM (trade name, manufactured by Kagaku Kogyo Co., Ltd.) was used and the compounding ratios thereof were changed to the ratios shown in Table 1 below. A sheet was prepared.

With respect to each vinyl chloride resin sheet obtained in the above Examples and Comparative Examples, impact resistance, secondary moldability,
The hygroscopicity was measured, and the results are shown in Table 1 below. The measuring method and evaluation of each characteristic are as follows.

[Impact resistance] Izod impact strength was measured according to JIS K 6745. The impact strength is usually required to be ²⁰ kJ / m ² or more at room temperature. If it is smaller than this, cracking is likely to occur due to impact during machining such as cutting or during use.

[Secondary Formability] Whether or not the sheet can be formed to a sufficient forming ratio in vacuum forming is determined. This is reflected in the elongation when the sheet is pulled.
The elongation (%) at break at 180 ° C. was measured according to K 6745, and this was used as an index of secondary formability. The material for secondary molding has an elongation of 300 at 180 ° C.
% Or more is required.

[Hygroscopicity] Hygroscopicity is the ease with which moisture in the air is absorbed and is proportional to the water absorption rate.
The water absorption was measured according to 7209. If the water absorption exceeds 0.04%, foaming may occur due to heating during secondary molding.

[0025]

[Table 1] From the results of Table 1, a vinyl chloride resin sheet obtained by using the vinyl chloride resin composition of the present invention (Examples 1 to 3)
Is excellent in impact resistance, secondary moldability, and moisture absorption resistance, and is extremely excellent in comprehensive evaluation, and it is clear that it has high suitability as a material for secondary molding. On the other hand, vinyl chloride resin sheets (Comparative Examples 1 to 6) obtained from compositions in which one or both of the components (a) and (b) are mixed in an inappropriate amount, and the component (b) are usually used instead of the components. The vinyl chloride resin sheets (Comparative Examples 7 and 8) obtained from the composition using the acrylic rubber-based modifier described above have insufficient impact resistance, secondary moldability, or moisture absorption resistance. It can be seen that the material cannot be used or has low suitability as the material for the next molding.

[0026]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a high-quality molded product having good impact resistance and secondary moldability, excellent moisture absorption resistance, and less likely to cause foaming due to heating during secondary molding. Provided is a vinyl chloride-based resin composition that can be produced efficiently at low cost.

Claims (1)

(57) [Claims] 1. A composite rubber having a structure in which (a) 100 parts by weight of a vinyl chloride resin, (b) a polyorganosiloxane rubber component and a polyalkyl (meth) acrylate rubber component are inseparably entangled with each other. 5.0 to 6.0 parts by weight of a graft copolymer obtained by graft-polymerizing one or more vinyl monomers, (c) methyl methacrylate and another alkyl (meth) acrylate, and a copolymer thereof. A vinyl chloride resin composition containing 2.5 to 8 parts by weight of a copolymer with another polymerizable monomer.