JP2005344048A - Modifying agent for polystyrene - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a modifying material which can largely modify the weather resistance and thermal stability of polystyrene resin. <P>SOLUTION: This modifying material for polystyrene comprises 100 pts. wt. of (A) a graft copolymer obtained by copolymerizing 40 to 95 pts. wt. (total) of monomers comprising 10 to 30 wt. % of a (meth)acrylate-based monomer and 90 to 70 wt. % of a styrenic monomer in the presence of 5 to 60 pts. wt. of an acrylate-based rubbery polymer having a gel content of ≥85 % and a weight-average particle diameter of 0.5 to 1.5 μm, 0.1 to 5 pts. wt. of a hindered amine-based photostabilizer and/or an antioxidant, and 0.01 to 1 pt. wt. of a silicone oil. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a modifier for polystyrene. In detail, it is related with the modifier which can improve the weather resistance and thermal stability of a polystyrene resin significantly.

Polystyrene resin is widely used as a material to replace metal and wood, and many of them add butadiene elastomer as an impact strength improver in order to obtain practical strength. However, such butadiene-based elastomers are easily deteriorated easily by heat during molding, ultraviolet rays or ozone during use, and the present situation is that there are restrictions on recycling and use environment.
For such problems, AES resins and ASA resins in which the elastomer component is replaced with an ethylene-propylene elastomer or an acrylate elastomer have been proposed, but the low hygroscopicity and stretchability that are characteristic of polystyrene resins are proposed. At present, the processing characteristics are greatly deteriorated.
In addition, each of the following patent documents describes an impact modifier using a specific acrylic rubber, but it is satisfactory as a modifier for polystyrene resin in terms of weather resistance and physical property balance. The current situation is that nothing is available.
Japanese Examined Patent Publication No. 6-65703 Japanese Patent Laid-Open No. 11-228799

  The objective of this invention is providing the modifier which can improve the weather resistance and thermal stability of a polystyrene resin significantly.

As a result of intensive studies in view of such problems, the present inventors have obtained a specific amount of a hindered amine light stabilizer and a specific amount of a hindered amine light stabilizer and a graft copolymer comprising a specific acrylic ester rubber-like polymer and a specific monomer composition. The inventors have found that the above-mentioned problems can be achieved by combining an antioxidant and silicone oil, and the present invention has been achieved.
That is, the present invention provides a (meth) acrylic acid ester in the presence of 5 to 60 parts by weight of an acrylic acid ester rubbery polymer having a gel content of 85% or more and a weight average particle diameter of 0.5 to 1.5 μm. 100% by weight of graft copolymer (A) obtained by copolymerizing 40 to 95 parts by weight of monomer (total) consisting of 10 to 30% by weight of monomer and 90 to 70% by weight of styrene monomer The present invention provides a polystyrene modifier comprising 0.1 to 5 parts by weight of a hindered amine light stabilizer and / or antioxidant and 0.01 to 1 part by weight of silicon oil per part.

  By adding a small amount of the polystyrene resin modifier in the present invention to the polystyrene resin, the weather resistance and thermal stability can be greatly improved.

  Hereinafter, the present invention will be described in detail.

 The acrylic ester rubber constituting the graft copolymer (A) in the present invention is an acrylic ester having 1 to 16 carbon atoms in the alkyl group in the presence or absence of a crosslinking agent, such as methyl (meth) acrylate. , Ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc., or other copolymerizable other compounds as required For example, rubber formed by polymerizing or copolymerizing one or more of styrene, acrylonitrile, methyl methacrylate, allyl methacrylate and the like.

The weight average particle diameter of the acrylate rubber is required to be 0.5 to 1.5 μm. If the weight average particle diameter is less than 0.5 μm, sufficient impact strength cannot be obtained, and if it exceeds 1.5 μm, the productivity is greatly reduced, which is not preferable.
Further, the gel content (toluene solvent) of the acrylate rubber must be 85% by weight or more. If the gel content is less than 85% by weight, the productivity is greatly reduced and the appearance of the final product is liable to deteriorate due to the influence of aggregation or orientation, which is not preferable.

The gel content and the weight average particle diameter of the rubbery polymer can be adjusted by changing the polymerization conditions of the rubbery polymer, for example, the polymerization method, polymerization temperature, polymerization time and the like. In particular, when adjusting the weight average particle size, it is also possible to obtain a polymer having an arbitrary particle size by a conventional agglomeration method after polymerizing a rubber-like polymer of less than 0.5 μm in advance.
The gel content and the weight average particle size were measured by the following method.
Gel content: About 10 g of a rubbery polymer was precisely weighed (a), dissolved in toluene, and after 48 hours, filtered through a glass filter that had been weighed in advance. The solid content remaining on the glass filter after drying was precisely weighed together with the glass filter, and the weight (b) of the toluene insoluble part was obtained by subtracting the weight of the glass filter alone from the weight at this time. The gel content was measured from the weight thus obtained using the following formula.
Gel content = b / a x 100 (%)
Weight average particle diameter: Submicron particle size distribution measuring apparatus N4Plus type (manufactured by Beckman Coulter, Inc.) was used and measured at 23 ° C. atmosphere.

The (meth) acrylic acid ester monomer constituting the graft copolymer (A) in the present invention is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2 -At least one selected from ethylhexyl acrylate and the like, and the styrene monomer is styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methyl-p- It is at least one monomer selected from methyl styrene, halogenated styrene, ethyl styrene, p-isopropyl styrene, pt-butyl styrene, 2,4-dimethyl styrene, divinylbenzene and the like.
In the monomer composition constituting the graft copolymer (A) in the present invention, if the (meth) acrylic acid ester monomer is less than 10% by weight (more than 90% by weight of the styrene monomer), the weather resistance is improved. The effect is not obtained, and if it exceeds 30% by weight (less than 70% by weight of styrene monomer), the hygroscopicity is extremely lowered, which is not preferable.

The graft ratio of the graft copolymer (A) and the intrinsic viscosity of the acetone-soluble component in the present invention are not particularly limited, but the graft ratio is 20% or more and the intrinsic viscosity of the acetone-soluble part (30 ° C. , Dimethylformamide) is preferably 0.4 or more.
If the graft ratio is less than 40% or the intrinsic viscosity of the acetone soluble part is less than 0.4, it is not practical because sufficient product strength cannot be obtained.
These graft ratios and intrinsic viscosities can be adjusted by changing the polymerization conditions during graft polymerization, such as the ratio of the rubber-like polymer to the monomer mixture, the polymerization temperature, the polymerization time, and the amount of molecular weight regulator added. It is.

The rubbery polymer and graft copolymer can be polymerized by known polymerization methods such as emulsion polymerization, bulk polymerization, solution polymerization, etc., and these polymerization methods may be combined, Emulsion polymerization is preferred.

As the antioxidant in the present invention, 2-6-di-t-butyl-4-methylphenol, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl)- Propionate, 2-2'-methylenebis (4-methyl-6-t-butylphenol), tetrakis- {methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate} -methane , 2-t-butyl-6- (3′-t-butyl-5′-methyl-2′-hydroxybenzyl) -4-methylphenyl acrylate and the like, phenolic antioxidants, trisnonyl phosphite, trisphenyl phosphite Phosphorous antioxidants such as phyto are exemplified and can be used alone or in combination of two or more.

Examples of the hindered amine light stabilizer in the present invention include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 2- (3,5-di-t- Butyl-4-hydroxybenzyl) -2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), dimethyl-1- (2-hydroxyethyl) -4-hydroxy succinate -2,2,6,6-tetramethylpiperidine polycondensate, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {2 , 2,6,6-tetramethyl-4-piperidyl} imino] hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], N, N′-bis (3-aminopropyl) ) Ethylenediamine-2,4-bis [N-butyl-N- (1,2,2.6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, bis ( 1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloxy-2,2,6,6- Tetramethylpiperidine and the like can be mentioned, and one or more can be used in combination.
In particular, it is preferable to use a hindered amine stabilizer having a molecular weight of 600 or more because it is difficult to sublimate when heated.

The usage-amount (total) of the said antioxidant and hindered amine type | system | group light stabilizer is 0.1-5 weight part per 100 weight part of graft copolymers (A). If it is less than 0.1 parts by weight, a sufficient effect cannot be obtained, and if it exceeds 5 parts by weight, problems such as mold contamination are likely to occur, which is not preferable.

Examples of the silicone oil in the present invention include polydimethylsiloxane, polymethylethylsiloxane, polydiethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, and the like, which can be used alone or in combination. . The molecular weight of these silicone oils is not particularly limited, but those having a viscosity at 25 ° C. in the range of 100 to 5000 cps are preferred because of easy handling.
These silicone oils are used in an amount of 0.01 to 1 part by weight per 100 parts by weight of the graft copolymer (A). If it is less than 0.01 part by weight, it is difficult to obtain a sufficient reforming effect, and if it exceeds 1 part by weight, the surface of the molded product tends to be damaged by bleed-out, which is not preferable.

Furthermore, the polystyrene modifier of the present invention can contain various additives such as a mold release agent, an antistatic agent, a lubricant and the like within a range that does not impair the properties thereof.

The polystyrene modifier of the present invention is 0.1 to 5 parts by weight of a hindered amine light stabilizer and / or antioxidant and 0.01 to 1 part of silicone oil per 100 parts by weight of the graft copolymer (A). There are no particular restrictions on the method of mixing these various components and the method of adding them to the polystyrene resin, and the mixture of the graft copolymer (A) and these additives is added to the polystyrene resin. A method of directly molding after addition, a method of granulating a pellet copolymer (A) and a mixture of these additives added to a polystyrene resin, pelletizing, and a method of molding or graft polymer (A) and these After the additive mixture is once granulated and pelletized, it can be added by any method such as a method of adding it to a polystyrene resin.

The mixing ratio with respect to the polystyrene resin when using the polystyrene modifier of the present invention is not particularly limited and can be appropriately determined according to the required performance of the final product, but from the viewpoint of cost effectiveness, the polystyrene resin 100 A ratio of 1 to 30 parts by weight of the modifier is preferred with respect to parts by weight.
Further, the mixture of the modifier and the polystyrene resin of the present invention may be (1) directly put into a molding machine and molded, or (2) once mixed with a granulator and pelletized, and then molded. May be.
In addition, there is no restriction | limiting in particular about the molding temperature in the case of obtaining a final product using the mixture of a modifier and a polystyrene resin, However It is preferable that it is 250 degrees C or less in order to cause the appearance defect by a silver streak or a burn. .
Moreover, the mixture of the modifier and polystyrene resin of the present invention can be molded by a molding method according to the purpose such as injection molding, extrusion molding, profile extrusion molding, pipe molding and the like.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by these.

〔Example〕
-Graft polymer (A)-
A-1: Graft comprising 50 parts (solid content) of polybutyl acrylate rubber latex (gel content: 95%) having a weight average particle size of 0.60 μm (solid content), 20 parts of methyl methacrylate and 30 parts of styrene by a known emulsion polymerization method A copolymer (A-1) was obtained. The resulting graft copolymer had a graft ratio of 40% and an intrinsic viscosity of the acetone soluble part of 0.55.

A-2: Graft comprising 50 parts (solid content) of polybutyl acrylate rubber latex (gel content: 92%) having a weight average particle size of 0.80 μm (solid content), 15 parts of methyl methacrylate and 35 parts of styrene by a known emulsion polymerization method A polymer (A-2) was obtained. The graft ratio of the obtained graft copolymer was 38%, and the intrinsic viscosity of the acetone soluble part was 0.57.

A-3: Graft composed of 80 parts (solid content) of polybutyl acrylate rubber latex (gel content: 89%) having a weight average particle diameter of 0.80 μm by a known emulsion polymerization method, 4 parts of methyl methacrylate, and 16 parts of styrene A polymer (A-3) was obtained. The graft ratio of the obtained graft copolymer was 23%, and the intrinsic viscosity of the acetone soluble part was 0.46.

A-4: Graft composed of 30 parts (solid content) of polybutyl acrylate rubber latex (gel content: 94%) having a weight average particle diameter of 0.80 μm by a known emulsion polymerization method, 15 parts of methyl methacrylate, and 55 parts of styrene A polymer (A-3) was obtained. The graft ratio of the obtained graft copolymer was 80%, and the intrinsic viscosity of the acetone soluble part was 0.61.

Ai: Graft comprising 50 parts (solid content) of polybutyl acrylate rubber latex (gel content: 92%) having a weight average particle size of 0.80 μm (solid content), 35 parts of methyl methacrylate and 15 parts of styrene by a known emulsion polymerization method. A polymer (A-i) was obtained. The graft ratio of the obtained graft copolymer was 43%, and the intrinsic viscosity of the acetone-soluble part was 0.58.

A-ii: Graft composed of 50 parts (solid content) of polybutyl acrylate rubber latex (gel content: 92%) having a weight average particle size of 0.20 μm (solid content), 15 parts of methyl methacrylate, and 35 parts of styrene by a known emulsion polymerization method. A polymer (A-ii) was obtained. The graft ratio of the obtained graft copolymer was 36%, and the intrinsic viscosity of the acetone soluble part was 0.51.

-Hindered amine light stabilizer-
Stabilizer-1; bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate: TINUVIN 770 manufactured by Ciba Specialty Chemicals Co., Ltd.
Stabilizer-2; poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {2,2,6,6-tetramethyl -4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}]: CHIMASSORB 944LD manufactured by Ciba Specialty Chemicals

-Antioxidant-
Antioxidant-1; phenolic antioxidant Ciba Specialty Chemicals Co., Ltd. Irganox 1076
Antioxidant-2; Phosphorous antioxidant
ADK STAB 135A manufactured by Asahi Denka Kogyo Co., Ltd.

-Silicon oil-
Silicon oil-1; polydimethylsiloxane KF96-100 manufactured by Shin-Etsu Chemical Co., Ltd.

[Examples 1-15, Comparative Examples 1-3]
About each said component, it mixed in the ratio shown in Table 1, and the predetermined | prescribed modifier pellet was obtained with the twin-screw extruder which set the cylinder temperature to 200 degreeC.
The obtained modifier pellets were pre-dried at 90 ° C. and then mixed at a ratio shown in Table 2 with respect to 100 parts by weight of polystyrene (G590 manufactured by Nippon Polystyrene Co., Ltd.), and the cylinder temperature was set to 200 ° C. After preparing predetermined pellets with an extruder, various test pieces were obtained at a cylinder temperature of 210 ° C. using an HP-100 injection molding machine manufactured by Hayabusa Iron Works. The results are shown in Table 2. Various test conditions are as follows.

Weather resistance : Using a test piece having a thickness of 3 mm, the yellowing degree difference ΔYI before and after irradiation with Sunshine WOM (black panel temperature: 63 ° C., no rainfall irradiation time: 300 hours) manufactured by Suga Test Instruments Co., Ltd. ) Measured with CMS-35SP manufactured by Murakami Color Research Laboratory.

Thermal stability : Using a Tanabe Plastics 40 mm single screw extruder (L / D = 32), the mixture P / L was re-granulated 10 times under the conditions of a set temperature of 230 ° C. and a screw rotation speed of 80 rpm. The tensile elongation was measured according to ISO 527 using P / L after re-granulation.
unit:%

Impact strength : Charpy impact strength (notched) was measured in accordance with ISO179.

The modifier in the present invention can greatly improve the weather resistance and thermal stability of the conventional polystyrene resin by adding a small amount to the polystyrene resin, and is suitably used in applications requiring these performances. be able to.

Claims (4)

In the presence of 5 to 60 parts by weight of an acrylic acid ester rubbery polymer having a gel content of 85% or more and a weight average particle size of 0.5 to 1.5 μm, (meth) acrylic acid ester monomer 10 A hindered amine-based light stabilizer per 100 parts by weight of the graft copolymer (A) obtained by copolymerizing 30% by weight and 40 to 95 parts by weight of a monomer (total) consisting of 90 to 70% by weight of a styrene monomer. A polystyrene modifier comprising 0.1 to 5 parts by weight of an agent and / or antioxidant and 0.01 to 1 part by weight of silicon oil. The polystyrene modifying material according to claim 1, wherein the graft copolymer (A) has a graft ratio of 20% or more and an intrinsic viscosity of the acetone-soluble part is 0.4 or more. The polystyrene modifier according to claim 1 or 2, wherein the antioxidant is at least one selected from a phenolic compound and a phosphorus compound. 4. The polystyrene modifier according to claim 1, wherein the hindered amine light stabilizer has a weight average molecular weight of 600 or more.