JPH08283526A - Impact-resistant resin composition - Google Patents

Abstract

PURPOSE: To obtain an acrylic resin composition having an excellent transparency and a high impact strength by mixing a silicone-modified acrylic polymer having a specified composition and a specified polymer structure with a multi- layer structure acrylic polymer and an acrylic polymer. CONSTITUTION: This composition comprises 10-90wt.%, in total, silicone-modified acrylic polymer (A) and multi-layer structure acrylic polymer (B) and 90-10wt.% acrylic polymer (C). Component A is a multi-layer structure polymer in which the first layer is made of a composite rubber obtained by radical-copolymerizing 0.05-25 pts.wt. polyorganosiloxane having vinyl-polymerizable functional groups with 99.95-75 pts.wt. (the total being 100 pts.wt.) at least one vinyl monomer, and the second layer made of a graft polymer comprising at least one vinyl monomer surrounds the first layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact-resistant resin composition, and more specifically, to a silicone-modified acrylic polymer, a multi-layered acrylic polymer, and a resin composition containing an acrylic polymer as a constituent component. Accordingly, the present invention relates to an acrylic impact-resistant resin composition having excellent transparency and impact resistance, which is suitable for use in automobile parts, industrial parts, home electric appliance parts and the like.

[0002]

BACKGROUND OF THE INVENTION Methyl methacrylate resin is excellent in transparency and weather resistance.
Although it is a molding material having a beautiful appearance, it has the drawback of low impact resistance.

Conventionally, it has been generally practiced that a hard resin is reinforced with an elastic body to impart impact resistance, and ABS resin is a typical resin of this kind. Since the diene rubber is used, the weather resistance is poor, and its outdoor use is a major drawback.

For this reason, various methods have been proposed for obtaining an impact resistant resin having weather resistance by using a rubber other than a diene rubber as an elastic body, and the use of an acrylic ester rubber is an example of this. Many studies have been made up to this point (Japanese Patent Publication No. Sho 49-11982).

As a non-diene rubber source having good weather resistance, a silicone rubber typified by polydimethylsiloxane can be mentioned. However, the use of the silicone rubber causes a problem that the transparency of the resin and the pigment coloring property are deteriorated. .

However, since the effect of improving the impact resistance by using the acrylic ester rubber is smaller than that of the diene rubber, the use of the methyl methacrylate resin containing the acrylic ester rubber is limited. .

Therefore, attempts have been made to improve the performance of acrylic rubbers, and a rubber-like polymer containing acrylic acid ester as a main component is formed on the outer shell of a hard polymer such as alkyl methacrylate, and the like. A graft copolymer having a three-layer structure of a hard polymer-rubber polymer-hard polymer, in which a hard monomer polymerization component such as an alkyl methacrylic acid ester is grafted on its outer shell, has been proposed (Japanese Patent Publication No. 48-55233).

[0008] However, according to this method, the impact resistance is improved while maintaining the excellent gloss of the acrylic resin and the excellent transparency including low and high temperatures. The improvement effect is not yet sufficient.

Further, when silicone-containing rubber is added to acrylic resin, it is difficult to achieve both transparency and impact resistance. For example, JP-A-6-25492 proposes to use a silicone-based graft composite rubber having a particle diameter of 0.01 to 0.07 μm in order to improve pigment coloring of the silicone-containing rubber. However, in this method, it is disclosed that the impact strength can be improved without significantly lowering the pigment coloring property of the acrylonitrile-styrene copolymer or polymethylmethacrylate,
No specific method for retaining the excellent transparency of the acrylic resin and imparting a high impact resistance to the acrylic resin is shown.

[0010]

Means for Solving the Problems As a result of intensive studies in view of the present situation, the present inventors have found that a silicone-modified acrylic polymer having a specific composition and a specific polymer structure and a multi-layered acrylic polymer are It has been found that an acrylic resin composition having excellent transparency and high impact strength can be obtained by blending it with an acrylic polymer, and has reached the present invention.

That is, the present invention relates to a silicone-modified acrylic polymer (A) and a multi-layered acrylic polymer (B).
And a total of 10 to 90% by weight, and an acrylic polymer (C) 90 to 10% by weight,
The above silicone-modified acrylic polymer (A) is a polyorganosiloxane having a vinyl polymerizable functional group 0.05 to
25 parts by weight and one or more vinyl monomers 9
9.95 to 75 parts by weight (total 100 parts by weight) is used as the first layer of the composite rubber obtained by radical copolymerization, and one or two or more vinyl-based monomer graft polymers are provided outside the first layer. An impact-resistant resin composition, which is a multi-layer structure polymer having a second layer made of

The silicone-modified acrylic polymer (A) used in the present invention is a first layer of a composite rubber obtained by radically polymerizing a polyorganosiloxane and one or more vinyl monomers. (Hereinafter, referred to as a rubber layer), and a second layer (hereinafter referred to as a graft layer) of a graft polymer of one or more vinyl monomers is provided on the outside thereof, and has a multilayer structure. Composed of united.

The polyorganosiloxane used to form the rubber layer is a polyorganosiloxane having vinyl polymerizable functional groups. The vinyl-polymerizable functional group contained in the polyorganosiloxane is not particularly limited as long as it can be copolymerized with the vinyl-based monomer, but preferable examples include a methacryl group, a vinyl group, a styryl group and the like. .

Polyorganosiloxanes having these polymerizable functional groups include, for example, dimethylsiloxane cyclic compounds such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane and trimethyltriphenylcyclotrisiloxane, and γ-methacryloyloxypropyldimethoxy. It can be obtained by an emulsion copolymerization method with an organosiloxane having a vinyl polymerizable functional group such as methylsilane, tetramethyltetravinylcyclotetrasiloxane and p-vinylphenyldimethoxymethylsilane.

The amount of the vinyl-polymerizable functional group contained in the polyorganosiloxane is preferably 0.1 mol% or more based on the siloxane unit, and the amount thereof is 0.1.
When it is less than 1 mol%, the resin becomes opaque and the impact strength improving effect becomes insufficient. It is preferably 0.5 mol% or more, and at this time, the effect of improving the transparency and impact strength of the resin becomes remarkable. Furthermore, the amount of vinyl polymerizable functional group contained in the polyorganosiloxane is
It is preferably 5 mol% or less. If it exceeds 5 mol%, the effect of improving impact strength may decrease. It is more preferably 3 mol% or less. The most preferable amount of vinyl polymerizable functional group contained in the polyorganosiloxane is in the range of 0.5 to 3 mol%. At this time, a high degree of transparency retention of the acrylic resin and a remarkable improvement in impact strength are simultaneously achieved.

Examples of the one or more vinyl monomers used for copolymerization with the polyorganosiloxane to form the rubber layer include aromatic vinyl compounds, unsaturated carboxylic acids, and unsaturated monomers. It is a monomer selected from carboxylic acid ester, butadiene and the like, and from the viewpoint of weather resistance, it is preferable to use an aromatic vinyl compound, unsaturated carboxylic acid or unsaturated dicarboxylic acid ester.

Examples of preferred aromatic vinyl compounds include styrene and α-methylstyrene, and preferred examples of unsaturated carboxylic acids and unsaturated carboxylic acid esters are acrylic acid, methacrylic acid, and 1 to 10 carbon atoms. 1
Mention may be made of acrylic acid esters and methacrylic acid esters having two alkyl groups.

The amount of polyorganosiloxane used to form the rubber layer is 100% by weight in total with one or more vinyl monomers used to copolymerize with the polyorganosiloxane. 0.05 to 25 parts
The range is parts by weight.

The amount of polyorganosiloxane used is 0.0
If the amount is less than 5 parts by weight, a superior impact resistance effect cannot be obtained as compared with the acrylic rubber alone. On the other hand, when it exceeds 25 parts by weight, the transparency of the resin is impaired. Further, it is not preferable to contain a large amount of relatively expensive polyorganosiloxane from the economical viewpoint. In order to achieve a clear impact resistance improving effect, the amount of polyorganosiloxane used is
It is preferably 0.1 part by weight or more, and more preferably 0.2 part by weight or more in order to obtain a remarkable effect. Furthermore, in order to keep the transparency of the resin high,
The amount of polyorganosiloxane used is preferably 10 parts by weight or less, and more preferably 6 parts by weight or less in order to achieve particularly good transparency. When the amount of the polyorganosiloxane used is 2 parts by weight or less, the transparency which is comparable to that of the conventional acrylic rubber can be achieved by itself.

The amount of one or more vinyl monomers used is in the range of 99.95 to 75 parts by weight based on 100 parts by weight of the total amount of the above polyorganosiloxane. If the amount used exceeds the above range, the transparency will be impaired. Preferably 99.9 to 75 parts by weight, more preferably 99.9 to 90 parts by weight, still more preferably 9
9.9-95.0 parts by weight, most preferably 99.8-9
It is 8.0 parts by weight.

The rubber layer in the present invention is composed of the above-mentioned components, but in order to crosslink the rubber layer and further improve the graft ratio of the vinyl-based monomer to be graft-polymerized on the rubber layer, the above-mentioned vinyl is used. It is preferable to use a polyfunctional compound such as di (meth) acrylate or allyl methacrylate of a diol having 2 to 6 carbon atoms in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the system monomer.

The average particle size of the rubber layer is preferably 0.05 μm or more from the viewpoint of improving impact strength,
When it is less than 05 μm, it is difficult to obtain good impact strength. A more preferable average particle diameter of the rubber layer is 0.08 μm or more. When the average particle diameter of the rubber layer is 0.08 μm or more, the effect of improving impact strength becomes remarkable. The most preferable average particle diameter of the rubber layer is 0.12 μm or more, and at this time, the greatest effect of improving impact strength is obtained. On the other hand, in order to keep the transparency of the resin good, the average particle diameter of the rubber layer is preferably 0.5 μm or less, and when the average particle diameter of the rubber layer exceeds 0.5 μm, the resin tends to be opaque. Show. A more preferable average particle diameter of the rubber layer is 0.25 μm.
Below, at this time, it becomes easy to maintain the high transparency inherent in the acrylic resin.

The emulsion polymerization method is most suitable for producing a rubber layer having such an average particle size. First, a latex of a polyorganosiloxane rubber comprising the above-mentioned constituents is prepared, and then the above-mentioned vinyl-based latex is used. It is preferable to add a monomer and polymerize. This emulsion polymerization can be performed by a known method.

The rubber layer thus prepared by emulsion polymerization can be graft-copolymerized with a vinyl monomer.

The vinyl-based monomer to be graft-polymerized on the rubber layer preferably contains at least 80% by weight or more of methyl methacrylate in the monomer used. When the amount of methyl methacrylate is less than 80% by weight, the compatibility with the acrylic resin is lowered and a resin having good impact strength cannot be obtained. Examples of other monomers of 20% by weight or less that can be used in combination with methyl methacrylate in the graft polymerization include (meth) acrylic acid esters such as methyl acrylate, ethyl acrylate and ethyl methacrylate. These vinyl-based monomers can be used alone or in combination of two or more.

When the graft polymerization is carried out, the ratio of the vinyl monomer to the rubber layer is 1 per 100 parts by weight of the rubber layer.
A range of 0 to 500 parts by weight is preferable. If the amount is less than 10 parts by weight, the compatibility with the acrylic resin is insufficient, so that the effect of improving the impact strength is not observed, and if it exceeds 500 parts by weight, the effect of improving the impact strength when added to the acrylic resin is relatively high. It becomes too low to be practical. It is more preferably in the range of 30 to 150 parts by weight, and most preferably in the range of 45 to 100 parts by weight, based on 100 parts by weight of the rubber layer. In the most preferable range, the impact strength, transparency, fluidity, etc. of the acrylic resin can all be maintained at good levels.

The graft polymerization method is not particularly limited,
Emulsion polymerization is preferably used and can be obtained by mixing the respective components and copolymerizing them in a single stage or multiple stages.

The refractive index of the rubber layer and the graft layer can be matched with the refractive index of the acrylic resin by adjusting the amount ratio of the monomer components used according to a known method.

Next, the multi-layered acrylic polymer (B) used in the present invention is an acrylic polymer having a multi-layered structure of two layers or three or more layers, and is disclosed in, for example, JP-A-62-230841. It can be produced by a known sequential multi-stage polymerization described in, for example. The most preferable one is a hard core type multi-layer structure containing a crosslinked hard layer in the innermost layer. Such a multi-layered acrylic polymer is commercially available as, for example, Acrypet (registered trademark) IR371, IR440 manufactured by Mitsubishi Rayon Co., Ltd. and can be used.

The acrylic polymer (C) used in the present invention is a methyl methacrylate unit 80-1.
It is an acrylic polymer composed of 00% by weight and 20 to 0% by weight of an alkyl acrylate unit having an alkyl carbon number of 1 to 8 and a weight average molecular weight of 50,000 to 10,000.
It is in the range of 0.

In the resin composition of the present invention, the above silicone-modified acrylic polymer (A), multi-layered acrylic polymer (B) and acrylic polymer (C) are blended in proportions based on the total resin composition. Silicone modified acrylic polymer (A) and multi-layered acrylic polymer (B) total 1
0 to 90% by weight, preferably 15 to 60% by weight, the acrylic polymer (C) is 90 to 10% by weight, preferably 85
The range is up to 40% by weight. Outside this range, the elastic modulus and fluidity of the resin will decrease.

The mixing ratio of the silicone-modified acrylic polymer (A) and the multi-layered acrylic polymer (B) is not particularly limited as long as the object of the present invention can be achieved,
The weight ratio of the silicone-modified acrylic polymer (A) / (silicone-modified acrylic polymer (A) + multilayer structure acrylic polymer (B)) is preferably in the range of 0.03 to 0.9, If it is less than 0.03, no sufficient effect of improving impact resistance is observed, while if it exceeds 0.9, the transparency of the acrylic resin is impaired. The range is more preferably 0.3 to 0.7, and in this range, the transparency and impact resistance of the acrylic resin can all be maintained at good levels.

As a method for preparing the resin composition of the present invention, the above silicone-modified acrylic polymer (A), multi-layered acrylic polymer (B) and acrylic polymer (C) are mixed in a Banbury mixer, A known device such as a shaft extruder may be used to mechanically mix and shape into pellets.

Further, if necessary, known stabilizers, lubricants, ultraviolet absorbers, colorants, antioxidants and the like can be added to the resin composition of the present invention.

[0035]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. The physical properties used in the examples were measured by the methods shown below.

(1) Total light transmittance (%) Measured in accordance with ASTM D542.

(2) Haze value (%) It was measured according to ASTM D542.

(3) Izod impact strength (kg · cm /
cm) Measured in accordance with ASTM D D256 (notched).

Production Example of Silicone Modified Acrylic Polymer (A) (1) Production of Silicone Emulsion Octamethylcyclotetrasiloxane 95 parts by weight γ-methacryloyloxypropyldimethoxymethylsilane 5 parts by weight (1.5 mol%) dodecylbenzene Sodium sulfonate 0.7 parts by weight Water 310 parts by weight was forcibly emulsified with a homogenizer to obtain a pre-emulsion. Then, 14 parts by weight of dodecylbenzenesulfonic acid 90 parts by weight of water were charged into a reaction vessel equipped with a stirrer and a reflux condenser,
Heated to 90 ° C. Then, the above pre-emulsion was added dropwise to this reaction container over 4 hours. After completion of the dropping, heating and stirring were continued for another hour, and then the reaction solution was cooled and neutralized to obtain a silicone emulsion.

(2) Production of Silicone-Acrylic Composite Rubber 5 parts by weight of the above silicone emulsion (1 part by weight as a silicone polymer component) 311 parts by weight of water was placed in a reaction vessel equipped with a nitrogen gas introducing tube, a stirrer and a reflux cooling tube. At the time of charging and heating to 80 ° C. after purging with nitrogen gas, 0.0004 parts by weight of ferrous sulfate, 0.0012 parts by weight of ethylenediaminetetraacetic acid sodium salt and 0.48 parts by weight of Rongalit were added, and then butyl was added. Acrylate 79.7 parts by weight Styrene 19.3 parts by weight Allyl methacrylate 0.9 parts by weight Polyoxyethylene alkylphenyl ether sodium phosphate (LO-529 manufactured by Toho Kagaku) 1 part by weight Tertiary-butyl hydroperoxide 0.3 parts by weight The mixture consisting of It continued heating and stirring time, to obtain a silicone-acrylic composite rubber emulsion. The obtained emulsion has an average particle size of 0.1.
It was 2 μm.

(3) Production of Silicone-Modified Acrylic Polymer (A) With 400 parts by weight of the silicone-acryl composite rubber emulsion in the reaction vessel, 0.12 parts by weight of Rongalit was continuously added at 80 ° C. Methyl methacrylate 57 parts by weight Methyl acrylate 3 parts by weight Octyl mercaptan 0.25 parts by weight LO-529 0.4 parts by weight Tertiary-butyl hydroperoxide 0.15 parts by weight A mixed solution consisting of 0.15 parts by weight is added dropwise over 1.5 hours. The heating and stirring were continued for another hour. The obtained latex is put into a warm 5 wt% calcium chloride aqueous solution, salted out and coagulated,
Then, dehydration and washing were repeated and then dried to obtain a silicone-modified acrylic polymer (A).

[Example 1, Comparative Examples 1 to 3] The silicone-modified acrylic polymer (A) and the multi-layered acrylic polymer (B) produced in the above production examples (Mitsubishi Rayon Co., Ltd.)
Manufactured by Acrypet (registered trademark) IR371)) and an acrylic polymer (C) (manufactured by Mitsubishi Rayon Co., Ltd., Acrypet VH) at a ratio shown in Table 1, and 25 mmφ
Was melt-kneaded at 230 ° C. and extruded into pellets. The pellets were injection-molded to prepare various test pieces, and the physical properties were evaluated. The results are shown in Table 1.

[0043]

[Table 1]

[0044]

The impact resistant resin composition of the present invention has extremely high impact resistance while retaining the excellent transparency of acrylic resin, and therefore is extremely suitable for use in automobile parts, industrial parts, home electric appliance parts and the like. It is useful.

Claims (1)

[Claims] 1. A silicone-modified acrylic polymer (A)
And 90 to 90 in total of the multi-layered acrylic polymer (B)
% Of the acrylic polymer (C) and 90 to 10% by weight of the acrylic polymer (C), wherein the silicone-modified acrylic polymer (A) is a polyorganosiloxane having a vinyl polymerizable functional group of 0.05 to A composite rubber obtained by radically copolymerizing 25 parts by weight and 99.95 to 75 parts by weight of one or more vinyl monomers (total of 100 parts by weight) is used as the first layer, and the outer layer is provided outside the first layer. An impact-resistant resin composition, which is a multi-layered polymer provided with a second layer composed of a graft polymer of one or more vinyl monomers.