JP2006265407A - Transparent resin composition excellent in surface hardness and transparent resin molded product obtained by molding the resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent resin composition excellent in transparency, surface hardness and impact strength, and to provide various molded products using the composition. <P>SOLUTION: The transparent resin composition excellent in surface hardness comprises 60-87 pts.wt polymethylmethacrylate resin (A), 3-10 pts.wt. graft polymer (B) obtained by graft polymerization of (total) 40-95 pts.wt. monomer mixture comprising 60-80 wt.% (meth)acrylate, 40-20 wt.% styrene and 0-20 wt.% copolymerizable other monomer in the presence of 5-60 pts.wt. rubber-like polymer having 0.5-0.8 μm volume-average particle diameter and comprising 3-10 wt.% styrene and 97-90 wt.% butadiene, and 10-37 pts.wt. copolymer (C) comprising 15-23 pts.wt. vinyl cyanide and 85-77 pts.wt. styrene (total of A+B+C is 100 pts.wt.), wherein total light transmittance of a resin molded product (3 mm thickness) thereof is ≥80% and pencil hardness (JIS K-5400) is ≥F. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transparent resin composition having excellent surface hardness and transparency, and a surface that can be suitably used for housings such as liquid crystal TVs and personal computer monitors, diffusion plates, light guide plates, and various lens applications. The present invention relates to a transparent resin composition having excellent hardness.

For resin molded products that require design properties, such as TV and personal computer housings or home appliances, the product value is greatly impaired by scratches, so materials with high surface hardness are often required. . In such a case, a PMMA (polymethylmethacrylate) -based resin material having a high surface hardness is often used. However, although the hardness is high, there is a tendency that a molded product is missing or cracked due to insufficient strength. Has the disadvantages.
In order to improve these defects, for example, it is proposed to improve the strength deficiency by adding a small amount of a rubber component. However, in this case, since sufficient surface hardness cannot be obtained, There is a demand for a resin material having a balanced performance.
Patent Document 1 (Japanese Patent Laid-Open No. 2001-226547) discloses a styrene- (meth) acrylate ester system having a specific weight average molecular weight forming a continuous phase with a graft copolymer having a specific rubber particle diameter forming a dispersed phase. A rubber-modified styrenic resin composition having improved transparency, surface hardness and the like made of a copolymer has been proposed. However, with the rubber content in the resin composition described in Patent Document 1, the target surface hardness (pencil hardness) of the present invention cannot be obtained. Therefore, at present, there is a strong demand for transparent resin materials having an excellent balance between surface hardness and strength.
JP 2001-226547 A

An object of the present invention is to provide a transparent resin composition having an excellent balance between surface hardness and strength.

That is, the present invention provides a rubber-like rubber having a volume average particle diameter of 0.5 to 0.8 μm composed of 60 to 87 parts by weight of polymethyl methacrylate resin (A), 3 to 10% by weight of styrene and 97 to 90% by weight of butadiene. In the presence of 5 to 60 parts by weight of polymer, (meth) acrylic acid ester monomer 60 to 80% by weight, styrene monomer 40 to 20% by weight and other copolymerizable monomers 0 to 20 3 to 10 parts by weight of graft polymer (B) obtained by graft polymerization of 40 to 95 parts by weight of a monomer mixture (total) consisting of 10% by weight, 15 to 23 parts by weight of vinyl cyanide monomer, and a single amount of styrene Copolymer (C) consisting of 85 to 77 parts by weight of a resin composition (A + B + C total 100 parts by weight) consisting of 10 to 37 parts by weight, and total light transmission when a resin molded product (3 mm thickness) is obtained Rate is 80% or more, One pencil hardness (JIS K-5400) is one that provides a transparent resin composition which is excellent in surface hardness, characterized in that at least F.

According to the present invention, a transparent resin composition having an excellent balance of surface hardness, transparency, impact strength, and heat resistance can be obtained, and can be developed to various molded products that require these performances.

The present invention will be described in detail below.
The transparent resin composition in the present invention has a volume average particle diameter of 0.5 to 0.8 μm composed of 60 to 87 parts by weight of polymethyl methacrylate resin (A), 3 to 10% by weight of styrene and 97 to 90% by weight of butadiene. In the presence of 5 to 60 parts by weight of a rubbery polymer, 60 to 80% by weight of (meth) acrylic acid ester monomer, 40 to 20% by weight of styrene monomer, and other copolymerizable monomers 3 to 10 parts by weight of graft polymer (B) obtained by graft polymerization of 40 to 95 parts by weight of monomer mixture (total) of 0 to 20% by weight, 15 to 23 parts by weight of vinyl cyanide monomer, styrene A resin composition comprising 10 to 37 parts by weight of a copolymer (C) comprising 85 to 77 parts by weight of a monomer (a total of 100 parts by weight of A + B + C).

 The polymethyl methacrylate resin (A) used in the present invention is a resin mainly composed of methyl methacrylate, and for example, commercially available Sumipex MG5 (manufactured by Sumitomo Chemical Co., Ltd.), Sumipex MHF (Sumitomo Chemical Co., Ltd.). And the like).

The rubber-like polymer constituting the graft polymer (B) used in the present invention is a copolymer composed of styrene and butadiene. However, when the styrene content is less than 3% by weight, the transparent polymer that is a feature of the present invention is used. When the amount is more than 10 parts by weight, it is not preferable because the low-temperature characteristics and transparency, which is a feature of the present invention, are also deteriorated.
Further, if the volume average particle diameter of the rubber-like polymer is less than 0.5 μm, it is difficult to obtain a sufficient impact strength, and if it exceeds 0.8 μm, the transparency is significantly impaired. Preferably it is 0.6-0.8 micrometer. The particle size of the rubbery polymer can be arbitrarily adjusted by changing the conditions during polymerization, that is, the type and amount of the polymerization initiator, the polymerization rate, the temperature during the polymerization, or the stirring conditions. Is possible.
The volume average particle size of the rubbery polymer was measured using a laser light diffraction particle size distribution analyzer (SALD-1100 manufactured by Shimadzu Corporation) after dissolving 0.3 g of a sample in 30 ml of MEK.
As a polymerization method for these rubbery polymers, an emulsion polymerization method is generally used, but other polymerization methods such as a solution polymerization method and a bulk polymerization method, or any combination thereof may be used depending on the purpose. .
As the rubbery polymer constituting the graft polymer (B), a small particle diameter rubbery polymer having a volume average particle diameter of less than 0.4 μm is prepared by a known method (for example, a method of adding an acidic substance (Japanese Examined Patent Publication 42- 3112, JP-B-55-19246, JP-B-2-9601, JP-A-63-117005, JP-A-63-132903, JP-A-7-157501, and a method of adding an acid group-containing latex (JP-A-56-166201). , JP-A-59-93701, JP-A-1-126301, JP-A-8-59704) and the like, and a rubbery polymer having a volume average particle size of 0.5 to 0.8 μm obtained by agglomeration and enlargement. Is preferable in terms of impact strength.

Examples of the (meth) acrylate monomer constituting the graft polymer (A) in the present invention include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic. Butyl acid, 2-ethylexyl (meth) acrylate, etc. are styrene monomers such as styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methyl-p-methyl. Styrene, halogenated styrene, ethyl styrene, p-isopropyl styrene, pt-butyl styrene, 2,4-dimethyl styrene, divinyl benzene, etc. are exemplified, and one or more types may be selected and used. Is possible.
Examples of other copolymerizable monomers include vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, maleimide monomers such as N-phenylmaleimide and N-cyclohexylmaleimide, and acrylic acid. Examples thereof include unsaturated carboxylic acids such as methacrylic acid, and one or two or more of them can be selected and used.

The graft polymer (B) in the present invention is a (meth) acrylic acid ester monomer 60 in the presence of 5 to 60 parts by weight of a rubbery polymer having a volume average particle size of 0.5 to 0.8 μm. Obtained by graft polymerization of 40 to 95 parts by weight of a monomer mixture (total) consisting of ˜80% by weight, styrene monomer 40 to 20% by weight and other copolymerizable monomers 0 to 20% by weight. It is what If the rubbery polymer is less than 5 parts by weight, sufficient impact strength cannot be obtained, and if it exceeds 60 parts by weight, the surface hardness decreases. Furthermore, when the (meth) acrylic acid ester monomer in the monomer mixture is less than 60% by weight or more than 80% by weight, the transparency is significantly lowered.
Although there is no restriction | limiting in particular in the graft rate of the graft polymer (B) in this invention, It is preferable that it is the range of 40 to 100% from the point of the balance of impact strength and surface hardness.
The graft ratio of the graft polymer (B) is determined based on the polymerization conditions, that is, the mixing ratio of the rubber-like polymer and the monomer mixture during the graft polymerization, the type and amount of the initiator, the polymerization rate, and the temperature during the polymerization. It is possible to adjust arbitrarily by changing etc.

There is no restriction | limiting in particular in the polymerization method of the graft polymer (B) in this invention, It is also possible to combine emulsion polymerization method, solution polymerization method, block polymerization method, or these arbitrarily.

The copolymer (C) in the present invention is a copolymer comprising 15 to 23 parts by weight of a vinyl cyanide monomer and 85 to 77 parts by weight of a styrene monomer. When the styrene-based monomer in the copolymer (C) is less than 77% by weight or more than 85% by weight, the transparency is remarkably lowered.

Examples of the styrene monomer and vinyl cyanide monomer constituting the copolymer (C) in the present invention are the same as those described in the section of the graft polymer (B).

Although there is no restriction | limiting in particular in the weight average molecular weight and molecular weight distribution of a copolymer (C), a weight average molecular weight is 50,000-150,000 from the point of the balance of a moldability and impact strength, and molecular weight distribution (Q value) is 2-3. It is preferable that it is the range of these. The weight average molecular weight and molecular weight distribution of the copolymer (C) can be adjusted by changing the conditions during the polymerization, that is, the type and amount of the initiator, the polymerization rate, the temperature during the polymerization, or the stirring conditions. It is possible to adjust to.
In addition, the polymerization method of the copolymer (C) in the present invention is not particularly limited, and an emulsion polymerization method, a solution polymerization method, a bulk polymerization method, or any combination thereof can be used.

When the polymethyl methacrylate resin (A) in the transparent resin composition in the present invention is less than 60 parts by weight or more than 87 parts by weight, transparency which is a feature of the present invention is impaired. Preferably, it is the range of 60-80 weight part. If the graft polymer (B) is less than 3 parts by weight, the required impact strength cannot be obtained, and if it exceeds 10 parts by weight, the surface hardness decreases, which is not preferable. Preferably it is 3-7 weight part. When the copolymer (C) is less than 10 parts by weight or exceeds 37 parts by weight, the transparency which is a feature of the present invention is impaired. Preferably, it is 10-30 weight part.

The transparent resin composition in the present invention is required to have a total light transmittance of 80% or more and a pencil hardness (JIS K-5400) of F or more when formed into a resin molded product (3 mm thickness). In order to make the total light transmittance 80% or more or the pencil hardness F or more, it is possible to appropriately adjust the particle diameter of the rubber-like polymer to be used, the kind of the monomer to be used, and the use ratio thereof.

Furthermore, pigments, dyes, antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, and the like can be added to the transparent resin composition of the present invention as necessary. Alternatively, it is preferable to add at least one selected from a phosphorus-based antioxidant and a benzotriazole-based light stabilizer from the viewpoint of preventing discoloration of the product during processing. In addition, it is preferable that these additives are 0.01-5.0 weight part with respect to 100 weight part of transparent resin compositions, and if it is less than 0.01 weight part, each addition effect cannot be acquired, but 5 weight Exceeding the range of the part is not preferable because there is a high possibility that the appearance of the molded product will be remarkably impaired.

There is no restriction | limiting in particular in the mixing method of each component which comprises the transparent resin composition of this invention, It can mix using an extruder, a Banbury mixer, a roll, a kneader, etc.
Moreover, the transparent resin composition of this invention can produce the target molded article easily by a normal injection molding method. In addition, it is possible to employ an injection molding method of two or more colors, a heat cycle molding method, an injection-compression molding method, or the like using an injection molding machine having a plurality of cylinders in combination with another thermoplastic resin. In addition to the injection molding method, it is also possible to adopt a modified extrusion method such as a sheet, extrusion, and pipe. Although there is no restriction | limiting in particular about the processing temperature at the time of shaping | molding, It is preferable that it is the range of 200-280 degreeC from a viewpoint which prevents coloring of a molded article.

The transparent resin molded part obtained above can be suitably used as a part for various molded products such as housings such as liquid crystal TVs and monitors for personal computers, and other home appliances.

〔Example〕
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not restrict | limited at all by these.

Polymethyl methacrylate resin (A)
A-1: Sumipex MG5 (manufactured by Sumitomo Chemical Co., Ltd.)
A-2: Sumipex MHF (manufactured by Sumitomo Chemical Co., Ltd.)

Graft polymer (B)
B-1 : 50 parts by weight (solid content) of styrene-butadiene rubber latex (5% by weight of styrene, volume average particle size 0.60 μm), 35 parts by weight of methyl methacrylate, 15 parts by weight of styrene by a known emulsion polymerization method A graft polymer B-1 comprising:
B-2 : 50 parts by weight (solid content) of styrene-butadiene rubber latex (5% by weight of styrene, volume average particle diameter 0.75 μm), 35 parts by weight of methyl methacrylate, 15% by weight of styrene by the same method as B-1. Part of graft polymer B-2 was obtained.
B-3 : 50 parts by weight (solid content) of styrene-butadiene rubber latex (10% by weight of styrene, volume average particle diameter of 0.50 μm), 30 parts by weight of methyl methacrylate, 20% by weight of styrene by the same method as B-1. Part of graft polymer B-3 was obtained.
B-i: B-1 and the same method by styrene - butadiene rubber latex (styrene 5 wt%, volume average particle diameter 0.32 [mu] m) 50 parts by weight (solid content), 35 parts by weight of methyl methacrylate, styrene 15 wt Part of graft polymer Bi was obtained.
B-ii : 50 parts by weight (solid content) of styrene-butadiene rubber latex (5% by weight of styrene, volume average particle diameter 0.60 μm), 20 parts by weight of methyl methacrylate, 30% by weight of styrene by the same method as B-1. Part of graft polymer B-ii was obtained.
B-iii : 50 parts by weight (solid content) of styrene-butadiene rubber latex (5% by weight of styrene, volume average particle diameter 0.90 μm), 35 parts by weight of methyl methacrylate, 15% by weight of styrene by the same method as B-1. Part of graft polymer B-iii was obtained.

Copolymer (C)
C-1 : A copolymer C-1 composed of 22% by weight of acrylonitrile and 78% by weight of styrene was obtained by a known bulk polymerization method. The copolymer C-1 had a polystyrene equivalent weight average molecular weight of about 100,000 and a Q value of 2.7.
C-2 : A copolymer C-2 comprising 18% by weight of acrylonitrile and 82% by weight of styrene was obtained by a known bulk polymerization method. The copolymer C-2 had a polystyrene equivalent weight average molecular weight of about 130,000 and a Q value of 2.6.
Ci : A copolymer Ci comprising 25% by weight of acrylonitrile and 75% by weight of styrene was obtained by a known bulk polymerization method. The copolymer Ci had a polystyrene equivalent weight average molecular weight of about 90,000 and a Q value of 2.9.
C-ii : Polystyrene C-ii comprising 100% by weight of styrene was obtained by a known bulk polymerization method. Polystyrene C-ii had a weight average molecular weight of about 90,000 and a Q value of 2.8.
C-iii : A copolymer C-iii comprising 70 parts by weight of methyl methacrylate and 30% by weight of styrene was obtained by a known bulk polymerization method. The copolymer C-iii had a weight average molecular weight of about 90,000 and a Q value of 2.5.

Additive (D)
D-1: Hindered amine light stabilizer ADK STAB LA-77G (Asahi Denka Kogyo)
D-2: Phenolic antioxidant Sumilizer BP-76 (manufactured by Sumitomo Chemical)

Examples and comparative examples After mixing various components at the ratios shown in Table 1, a 40 mm single screw extruder with a vent (manufactured by Tanabe Plastics Co., Ltd.) was used and the temperature was set at 220C. Melt mixing was performed. In addition, 1 part of ethylenebisstearylamide was added to all samples as a lubricant. The obtained pellets were prepared using a 3.5 ounce vertical injection molding machine (SAV-100, manufactured by Yamashiro Seiki Co., Ltd.) under the condition of a cylinder temperature of 220 ° C. and evaluated by the following test method. Carried out.

Impact strength : Charpy impact strength was measured according to ISO 179. Unit: kJ / m ²
Heat resistance : The deflection temperature under load was measured according to ISO 75. Unit: ° C
Pencil hardness : Pencil hardness was measured according to JIS K-5400.
Transparency : Total light transmittance (%) was measured using a reflection / transmittance meter HR-100 (manufactured by Murakami Color Research Laboratory).

The transparent resin molded product comprising the resin composition in the present invention is preferably used as a molded product requiring surface hardness and transparency, for example, a liquid crystal TV or personal computer housing, various liquid crystal protective sheets, and a plastic lens. Is possible.

Claims (5)

5 to 60 parts by weight of a rubbery polymer having a volume average particle diameter of 0.5 to 0.8 μm comprising 60 to 87 parts by weight of a polymethyl methacrylate resin (A), 3 to 10% by weight of styrene and 97 to 90% by weight of butadiene. In the presence of a part, a monomer comprising 60 to 80% by weight of (meth) acrylic acid ester monomer, 40 to 20% by weight of styrene monomer and 0 to 20% by weight of other copolymerizable monomers 3 to 10 parts by weight of graft polymer (B) obtained by graft polymerization of 40 to 95 parts by weight of the total body mixture (total), 15 to 23 parts by weight of vinyl cyanide monomer, 85 to 77 parts by weight of styrene monomer Copolymer (C) consisting of 10 to 37 parts by weight of a resin composition (A + B + C total 100 parts by weight) having a total light transmittance of 80% or more when formed into a resin molded product (3 mm thickness), And pencil hardness (JIS A transparent resin composition having excellent surface hardness, wherein K-5400) is F or more. Rubber having a volume average particle size of 0.5 to 0.8 μm obtained by agglomerating and expanding a rubbery polymer having a volume average particle size of less than 0.4 μm as the rubbery polymer constituting the graft polymer (B) The transparent resin composition having excellent surface hardness according to claim 1, wherein the polymer is used. The transparent resin composition excellent in surface hardness according to claim 1 or 2, wherein the graft ratio of the graft polymer (B) is in the range of 40 to 100%. Addition of 0.01 to 5.0 parts by weight of at least one selected from silicon compounds, phenolic or phosphorus antioxidants, and benzotriazole light stabilizers per 100 parts by weight of the resin composition (total of A + B + C) The transparent resin composition excellent in the surface hardness in any one of Claims 1-3 formed. The transparent resin molded product formed by shape | molding the resin composition in any one of Claims 1-4.