JP5047494B2 - Thermoplastic resin molded article and thermoplastic resin molded article subjected to surface secondary processing - Google Patents

Description

  The present invention relates to a thermoplastic resin molded article that solves the bronze phenomenon and has an excellent appearance design, and also has an excellent surface appearance and good appearance even in surface secondary processing such as painting, plating, and vapor deposition. It is related with the thermoplastic resin molded article in which the surface secondary processing obtained was given.

  Among rubber-reinforced styrene resins, especially acrylic rubber is added to impart impact resistance, and the blended resin is called AAS resin or ASA resin (hereinafter referred to as ASA resin). Positioned as a resin with an excellent balance of weather resistance, it is used in a wide range of fields such as automobile interior and exterior parts, housings for various home appliances and office automation equipment, and other miscellaneous goods.

Usually, such an ASA resin is colored by blending a colorant, and is generally used as a molded product molded by a molding method such as injection molding or extrusion molding. One of the matters to be noted in this toning / coloring process is “metamerism”. This is a phenomenon in which the color changes when the light source changes. For example, it is often seen that the color under room light does not match the color under sunlight. This phenomenon is caused by the colorant and can be solved by selecting the colorant. This phenomenon can be easily determined with the naked eye, and can be confirmed by a spectrophotometer as a numerical value (reflectance) or a graph (reflectance curve).
However, particularly in the case of injection-molded products, there are problems such as “bronze phenomenon” as well as the aforementioned metamerism.
“Bronze phenomenon” is a red to yellow color other than the original colored hue under direct sunlight or transparent glass through direct sunlight even though the hue is good under indoor sunlight and indoor lighting. This is a phenomenon in which the colors in the range appear to overlap, and the quality image is deteriorated and the commercial value is lowered in the appearance of the molded product. Of course, this bronze phenomenon and metamerism are different phenomena. As a weather-resistant resin that solves such a bronze phenomenon, for example, a method is proposed in which the total amount of rubber particles having a weight average particle diameter in the range of 0.20 to 0.35 μm is less than 20% by weight based on the total weight of the rubber. (Patent Document 1: Japanese Patent Laid-Open No. 63-275617).
In addition, in Japanese Patent Application Laid-Open No. 2000-17135 (Patent Document 2), an ASA resin composition in which the bronzing phenomenon is solved by a method in which an acrylic ester rubber having a weight average particle diameter of less than 0.2 μm is made 20% by weight or more. Has been proposed.
As shown in these publicly known documents, the use of ASA-based resins is disadvantageous in that complicated techniques such as fine adjustment of the rubber particle size and the amount of rubber are required in order to obtain appearance design. Furthermore, since it has a specific rubber particle size, it has a drawback that it adversely affects the surface appearance after surface secondary processing such as painting and plating.
JP-A 63-275617 JP 2000-17135 A JP 2001-18229 A JP 2001-269978 A

  An object of the present invention is to provide a thermoplastic resin molded article that solves the bronze phenomenon and has excellent weather resistance in an injection-molded ASA-based resin. It is another object of the present invention to provide an engineered thermoplastic resin molded article that has been subjected to surface secondary processing that has a good surface appearance after surface secondary processing.

The present inventors can solve the bronze phenomenon by injection molding at a specific mold temperature or higher when injection molding an ASA-based resin having a specific weight average particle diameter. The present inventors have found that a thermoplastic resin molded article subjected to surface secondary processing capable of obtaining a good surface appearance even after secondary processing can be obtained, and the present invention has been achieved.
That is, in the present invention, when the ASA resin (A) containing 5 to 40% by weight of an acrylate rubber having a weight average particle diameter of 0.1 μm or more is injection molded, the cavity surface temperature of the mold is previously determined. The present invention provides a thermoplastic resin molded product obtained by injection-filling a metal mold heated to a temperature higher than the heat distortion temperature of the ASA resin (A).

  The present invention can solve the bronze phenomenon by molding an ASA-based resin having a specific weight average particle diameter that causes a remarkable bronze phenomenon in a normal injection molding method at a specific mold temperature or higher. Because it does not require complicated particle size restrictions for rubber particles, it is a thermoplastic resin molded product that has been subjected to surface secondary processing that provides a good surface appearance even after surface secondary processing such as painting, plating, and vapor deposition. The effect that is obtained.

Hereinafter, the present invention will be described in detail.
The acrylate rubber constituting the ASA resin (A) in the present invention is an acrylate monomer having an alkyl group having 1 to 16 carbon atoms in the presence or absence of a crosslinking agent, such as methyl. One or two or more of acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc., and other copolymerizable monomers as necessary, for example, one or two of styrene, acrylonitrile, methyl methacrylate, etc. It is a rubber obtained by polymerizing more than seeds. Here, as a usable crosslinking agent, for example, divinylbenzene, allyl (meth) acrylate, ethylene glycol di (meth) acrylate, diallyl phthalate, dicyclopentadiene di (meth) acrylate, trimethylolpropane tri (meth) acrylate, Examples include pentaerythritol hexa (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, triallyl cyanurate, triallyl isocyanurate, and the like. Such an acrylate rubber can be usually polymerized by emulsion polymerization. In this case, a known emulsifier, for example, an anionic emulsifier such as sodium dodecylbenzenesulfonate, sodium oleate, or polyoxyethylene is used. Nonionic emulsifiers such as nonylphenyl ether can be used. As the polymerization initiator, water-soluble and oil-soluble initiators alone or redox-based, for example, inorganic initiators such as persulfate, organic peroxides such as t-butyl hydroperoxide, azo compounds, etc. It can be used alone or in combination with sulfite, sodium formaldehyde sulfoxylate and the like as a redox initiator. Furthermore, if necessary, a polymerization chain transfer agent such as t-dodecyl mercaptan can also be used. In the polymerization, an acrylate rubber having a desired particle diameter can be obtained by appropriately changing the emulsifier, electrolyte, initiator concentration, polymerization time and the like. Further, an acrylic ester rubber having a desired particle size can be obtained by agglomerating and enlarging an acrylic ester rubber having a small particle diameter by a known method.

In the present invention, the weight average particle diameter of the acrylate rubber constituting the ASA resin (A) is required to be 0.10 μm or more. When the weight average particle diameter of the acrylate rubber is less than 0.10 μm, the impact resistance is remarkably inferior. The rubber content in the ASA resin (A) is required to be 5 to 40% by weight from the viewpoint of impact resistance.
The ASA resin (A) includes 5 to 40% by weight of the acrylate rubber, 10 to 30% by weight of acrylonitrile monomer, 30 to 85% by weight of styrene monomer, and a copolymer thereof. It is preferably composed of 0 to 55% by weight of other possible monomers.

Examples of the styrene monomer constituting the ASA resin (A) in the present invention include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methyl-p-methylstyrene. , Halogenated styrene, ethyl styrene, p-isopropyl styrene, pt-butyl styrene, 2,4-dimethyl styrene, divinylbenzene and the like are exemplified, and one or more kinds can be selected and used. is there. Examples of the acrylonitrile-based monomer include acrylonitrile, methacrylonitrile, and the like, and one or more types can be selected and used.
Further, other monomers that can be copolymerized include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylexyl (meth) acrylate. (Meth) acrylic acid ester monomers such as maleimide monomers, maleimide monomers such as N-phenylmaleimide and N-cyclohexylmaleimide, and unsaturated carboxylic acids (anhydrides) such as acrylic acid, methacrylic acid and maleic anhydride ), Amide monomers such as acrylamide and methacrylamide, etc., are exemplified, and one or more can be selected and used.

  The ASA resin (A) in the present invention is composed of a styrene monomer, an acrylonitrile monomer and, if necessary, other monomers copolymerizable with these in the presence of the acrylate rubber described above. A graft polymer (A-1) obtained by polymerizing the monomer mixture, or the graft polymer (A-1), a styrene monomer, an acrylonitrile monomer, and a copolymer thereof. It is composed of a mixture of (co) polymer (A-2) obtained by polymerizing one or more monomers (mixtures) selected from other monomers, and finally obtained. What is necessary is just to make it the various components as ASA type resin obtained become said composition ratio.

  There is no limitation on the production method of the ASA resin (A) in the present invention, and a known emulsion polymerization method, bulk polymerization method, solution polymerization method, suspension polymerization method or a method in which these polymerization methods are arbitrarily combined is adopted. Can do.

  The ASA-based resin (A) of the present invention includes various additives as necessary, for example, known antioxidants, light stabilizers, lubricants, plasticizers, antistatic agents, colorants, flame retardants, matting agents, A filler etc. can be added suitably. In mixing, a known kneading apparatus such as an extruder, a roll, a Banbury mixer, or a kneader can be used.

Furthermore, the ASA resin (A) of the present invention can be mixed with other thermoplastic resins as necessary.
Examples of such other thermoplastic resins include polycarbonate resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin, rubber-reinforced polystyrene resin (HIPS resin), acrylonitrile-butadiene-styrene resin (ABS resin), acrylonitrile- Examples include ethylene-propylene-styrene resin (AES resin), methyl methacrylate-butadiene-styrene resin (MBS resin), and the like.

  As a molding method of the ASA resin (A) in the present invention, although it is the same process as a general injection molding method, the cavity surface temperature of the mold is preheated to the heat deformation temperature or more of the ASA resin (A). If this method is not adopted, the improvement effect of the bronze phenomenon which is the object of the present invention is not expected, and a good surface appearance after secondary surface processing is required. Since it cannot be obtained, it is not preferable.

As for the injection molding apparatus, a normal injection molding apparatus can be used, but the operating temperature range of the mold temperature controller for controlling the mold cavity surface temperature is higher than the heat deformation temperature of the ASA resin (A). It is necessary to have a device that can ascend.
In addition, a normal mold temperature controller can be used, but it is preferable to use oil or steam as a temperature control medium in consideration of use at a high temperature of 80 ° C. or more.
Furthermore, as the mold temperature control apparatus, it is more preferable to use a mold temperature control apparatus used in a heat cycle molding method in which the mold cavity surface temperature is repeatedly raised and lowered. Such a mold temperature controller is described in detail in Patent Document 3, for example.

〔Example〕
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, the part and% which are shown in an Example are based on a weight.

[Production of acrylic ester rubber (L-1)]
A nitrogen-replaced glass reactor was mixed with 230 parts pure water, 0.15 parts potassium oleate, 0.2 parts potassium persulfate, 98.0 parts butyl acrylate, 1.0 part acrylonitrile and 1.0 part allyl methacrylate. The monomer solution was charged and the temperature was raised to 50 ° C. Thereafter, an aqueous emulsifier solution consisting of 20 parts of pure water and 1.0 part of potassium oleate was continuously added over 12 hours. Thereafter, polymerization was continued for 5 hours to obtain an acrylate rubber latex (L-1) having a weight average particle size of 0.47 μm.
The weight average particle size was measured in a 23 ° C. atmosphere using a submicron particle size distribution analyzer N4Plus type (manufactured by Beckman Coulter Co., Ltd.). Measured in).

[Production of acrylic ester rubber (L-2)]
A nitrogen-replaced glass reactor was mixed with 230 parts pure water, 0.30 parts potassium oleate, 0.2 parts potassium persulfate, 98.0 parts butyl acrylate, 1.0 part acrylonitrile and 1.0 part allyl methacrylate. The monomer solution was charged and the temperature was raised to 50 ° C. Thereafter, an aqueous emulsifier solution consisting of 20 parts of pure water and 1.0 part of potassium oleate was continuously added over 8 hours. Thereafter, polymerization was continued for 5 hours to obtain an acrylate rubber latex (L-2) having a weight average particle size of 0.28 μm.

[Production of acrylic ester rubber (L-3)]
A nitrogen-replaced glass reactor was mixed with 250 parts pure water, 0.40 parts potassium oleate, 0.25 parts potassium persulfate, 98.0 parts butyl acrylate, 1.0 part acrylonitrile and 1.0 part allyl methacrylate. The monomer solution was charged and the temperature was raised to 50 ° C. Thereafter, an aqueous emulsifier solution composed of 20 parts of pure water and 2.0 parts of potassium oleate was continuously added over 3 hours. Thereafter, polymerization was continued for 5 hours to obtain an acrylate rubber latex (L-3) having a weight average particle size of 0.13 μm.

[Production of acrylic ester rubber (L-4)]
A glass reactor substituted with nitrogen was charged with 300 parts of pure water, 0.80 part of potassium oleate, and 0.3 part of potassium persulfate, and the temperature was raised to 65 ° C. Thereafter, a mixed monomer solution consisting of 99.0 parts of butyl acrylate, 1.0 part of acrylonitrile, 1.0 part of allyl methacrylate, 20 parts of pure water, and an aqueous emulsifier solution consisting of 3.5 parts of potassium oleate for 3 hours each. Added continuously. Thereafter, polymerization was continued for 6 hours to obtain an acrylate rubber latex (L-4) having a weight average particle size of 0.08 μm.

[Production of Graft Polymer (A-1-1-1)]
In a nitrogen-replaced glass reactor, 50 parts of acrylic ester rubber latex (L-1) (in terms of solid content), 110 parts of pure water, 0.1 part of dextrin, 0.1 part of anhydrous sodium pyrophosphate and ferrous sulfate After adding an aqueous solution in which 0.005 part was dissolved, the temperature was raised to 70 ° C. Thereafter, a mixed liquid of 15 parts of acrylonitrile, 35 parts of styrene, 0.3 part of cumene hydroperoxide and an aqueous emulsifier solution in which 1.0 part of potassium oleate was dissolved in 20 parts of pure water were continuously added over 6 hours. Thereafter, the polymerization was continued for 3 hours to complete the polymerization. Thereafter, salting out, dehydration and drying were performed to obtain a graft polymer (A-1-1).
Moreover, it manufactured similarly except having changed acrylic acid ester rubber latex as shown in Table 1, and obtained graft polymer A-1-2-4.

Copolymer (A-2-1)
A copolymer (A-2-1) composed of 30% by weight of acrylonitrile and 70% by weight of styrene was obtained by a known bulk polymerization.
Copolymer (A-2-2)
By a known solution polymerization, a copolymer (A-2-2) comprising 10% by weight of acrylonitrile, 50% by weight of styrene and 40% by weight of N-phenylmaleimide was obtained.

[Examples 1 to 4, Comparative Examples 1 to 8]
Carbon # 45 (manufactured by Mitsubishi Chemical Corporation) with respect to 100 parts in total of the graft polymer (A-1-1 to 4) and the copolymer (A-2-1 to 2) at the composition ratio shown in Table 2. ) Was mixed and melt-kneaded at 250 ° C. using a 40 mm twin screw extruder to form pellets. Various test pieces were produced from the obtained pellets with an injection molding machine, and the physical properties were measured.

In preparing test pieces for evaluating bronze phenomenon, paintability and plating properties, flat plates (150 mm × 90 mm × 2 mm) were formed using the following injection molding machine and heat cycle mold temperature control device.
In forming the flat plate, for each of the above compositions, the mold cavity surface temperature was kept constant at 50 ° C. (normal molding), and the heat deformation temperature of each composition (compared with Examples 1 to 3). Examples 1 to 5 were each molded at 90 ° C., and the cavity surface temperature of the mold was controlled (heat cycle molding) so that the temperature was higher by 5 to 10 ° C. than Example 4 and Comparative Examples 6 to 8 were each 110 ° C.) .
Injection molding machine: J-150EP Nippon Steel Works Heat cycle mold temperature controller: Temperature control unit for high-speed HC molding Mitsui Chemical Engineering Co., Ltd.

(1) Impact resistance: Notched Izod impact strength was measured according to ASTM D-256. 23 ° C, 1/8 inch. Unit: J / m
(2) Heat resistance: The heat distortion temperature was measured according to ASTM D-648. 1/4 inch, load stress 1.82 MPa.
(3) Bronze phenomenon: About the test piece obtained above, the bronze phenomenon was visually judged at noon outdoors and in direct sunlight. Bronze phenomenon was absent, Bronze phenomenon was slightly present, and bronze phenomenon was marked.
(4) Direct vapor deposition: For the test pieces obtained above, aluminum was vapor-deposited, and an organic solvent acrylic paint was applied as a top coat using an air spray gun. About the molded article after coating, the diffuse reflectance (total reflectance-regular reflectance) was measured with a digital reflectometer (reflectance angle: 45 °), and the vapor deposition surface was determined.
○: Diffuse reflectance less than 5%
X: Diffuse reflectance of 5% or more (5) Paint appearance: Coating treatment process: For the test piece obtained above, a black acrylic urethane paint (Recrack # 440N manufactured by Fujikura Kasei Co., Ltd.) is used in a film thickness of 25 μm. After spraying and setting for 5 minutes at room temperature, baking was performed in an oven at 80 ° C. for 30 minutes. The appearance of the coating after baking was visually judged.
○: Rough skin after painting, no suction phenomenon ×: Rough skin after painting, suction phenomenon is remarkable

The normal injection molding method can solve the bronze phenomenon by molding an ASA-based resin having a specific weight average particle diameter that causes a remarkable bronze phenomenon at a specific mold temperature or higher. Further, such as painting, plating, vapor deposition, etc. Also in the secondary surface processing, a secondary surface processed thermoplastic resin molded product that provides a good surface appearance can be obtained, and can be suitably used in the fields of vehicle interior and exterior, building materials, home appliances, office automation equipment, and the like. it can.

Claims (3)

Acrylic acid ester rubber having a weight average particle diameter of 0.1 μm or more is 5 to 40% by weight , acrylonitrile monomer is 10 to 30% by weight, styrene monomer is 30 to 85% by weight and copolymerizable with these. When the ASA resin (A) composed of 0 to 55% by weight of other monomers is injection-molded, the cavity surface temperature of the mold is previously set to be equal to or higher than the heat deformation temperature of the ASA resin (A). A thermoplastic resin molded product obtained by injection filling into a heated mold. The thermoplastic resin molded article according to claim 1 , wherein the molded article is formed by a heat cycle molding method in which the cavity surface temperature of the mold is repeatedly raised and lowered. A thermoplastic resin molded article obtained by subjecting part or all of the surface of the thermoplastic resin molded article according to any one of claims 1 to 2 to any surface secondary processing of coating, plating, or vapor deposition.