JPH0139899B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyester injection molded article having a matte pearlescent luster, which is obtained by subjecting an injection molded article made of a specific resin composition to matte processing. Polyethylene terephthalate has excellent mechanical properties and chemical resistance, and has relatively low gas permeability for oxygen, carbon dioxide, etc., and excellent transparency, making it a popular material for containers for foods, beverages, cosmetics, etc. part is used. Cosmetic containers, especially because they have excellent fragrance retention and chemical resistance, and do not alter the contents.
It is attracting attention for its use in caps, compacts, etc. By the way, in the field of application such as cosmetic containers, caps, compacts, etc., depending on the product type, not only molded products with excellent transparency but also high-quality pearl luster with excellent elegance and solidity are needed. It is desired that a molded product with excellent decorative properties be developed. However, conventional plastic molded products with pearlescent luster are simply too glittery and lack elegance and solidity. As a result of intensive studies in view of the current situation, the present inventors performed a specific matte processing treatment on an injection molded product made of a resin composition made by blending a specific amount of a specific resin with a specific amount of thermoplastic polyester resin. The present invention was achieved by discovering that a product can be made to have an elegant, profound feel and a matte pearlescent luster with an excellent surface appearance. The gist of the present invention is that the main repeating unit is ethylene terephthalate and the intrinsic viscosity is 0.75 to 0.75.
From a resin composition in which 50 to 95% by weight of a thermoplastic polyester resin of 1.40 is blended with 5 to 50% by weight of at least one type selected from the group consisting of methacrylic resin, saturated aliphatic olefin resin, and styrene resin. A polyester injection molded product having a matte pearlescent luster, which is obtained by subjecting the injection molded product to matte processing using a sandblasting method using an abrasive with a particle size of 300μ or less or a coating method using a matte agent with a particle size of 10μ or less. . The thermoplastic polyester resin in the present invention is one in which 75 mol% or more of the repeating units constituting the resin consists of ethylene terephthalate, and also includes copolymers. Copolymerization components include isophthalic acid, adipic acid, sebacic acid, p-β-oxyethoxybenzoic acid, diphenyl ether-4,4'-
Dicarboxylic acid components such as dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, etc. or their alkyl ester derivatives, glycols such as propylene glycol, butanediol, hexamethylene glycol, neopentyl glycol, cyclohexanedimethanol, etc. used. Thermoplastic polyester resins can be produced by polycondensation through transesterification, direct esterification, or solid phase polymerization of the polymer obtained by these methods. A polymer obtained by this method can be used, but its intrinsic viscosity [η] is 0.75
It needs to be in the range of ~1.40. [η] is
If it is less than 0.75, the mechanical strength of the final injection molded product will be low, and at the same time, the injection molded product itself will have little or no pearlescent luster. Even if matte processing is applied to the material, it is difficult to obtain the desired matte pearl luster, which is not preferable. On the other hand, if [η] exceeds 1.40, the injection molded product will have a strong pearlescent luster, but
This is not preferable because the processability of the molded product becomes extremely difficult. Here, [η] is a value determined from the solution viscosity measured at 25° C. in a 50/50 (weight ratio) solution of phenol/tetrachloroethane. In addition, the methacrylic resin in the present invention refers to a homopolymer of methyl methacrylate, a copolymer of 50 mol% or more of methyl methacrylate and another vinyl monomer that can be copolymerized with it, or a mixture of these polymers. It is. Other vinyl monomers that can be copolymerized with methyl methacrylate include acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, butyl acrylate, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, etc. . Next, the saturated aliphatic olefin resin in the present invention refers to ethylene, propylene, butene-1,4
Refers to homopolymers of methylpentene-1, isobutylene, etc., copolymers of these α-olefins with other copolymerizable monomers, or mixtures of these polymers. Specific examples of saturated aliphatic olefin resins include high-pressure, medium-low-pressure polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl acrylate copolymer, and ethylene-ethyl acrylate copolymer. Polymer, polypropylene, ethylene-propylene copolymer, poly-4-methylpentene-1, polyisobutylene, and the like. In carrying out the present invention, polyethylene, polypropylene, and ethylene-ethyl acrylate copolymers exhibit particularly excellent effects and are therefore preferred. Further, the styrenic resin used in the present invention refers to a homopolymer of styrene or styrene substituted with hydrogen at the α-position, a copolymer containing these as a main component, and a mixture of these polymers. As a specific example,
Examples include mixtures of polystyrene, poly-α-methylstyrene, styrene-acrylonitrile copolymers, styrene-butadiene copolymers and rubber-like substances. In the present invention, the injection molded product includes a methacrylic resin and a methacrylic resin in the above-mentioned specific thermoplastic polyester resin.
It is composed of a resin composition that is a blend of at least one type selected from the group consisting of a saturated aliphatic olefin resin and a styrene resin,
One type or two or more types of resins can be used for blending. The content of thermoplastic polyester resin in the resin composition constituting such an injection molded article needs to be 50% by weight or more. In particular, regarding the content of the resin to be blended, a resin composition containing 1 to 30% by weight of saturated aliphatic olefin resin and 1 to 49% by weight of other resins is used. In some cases, it is possible to produce an injection molded product with sufficient pearl luster, excellent chemical resistance, and excellent mechanical properties, especially impact resistance. This treatment is preferable because it allows a molded article to have the unique matte pearlescent luster that characterizes the present invention. In the present invention, additives such as dyes and pigments, ultraviolet absorbers, antistatic agents, nucleating agents, etc. may be added to the resin composition composed of the above-mentioned specific resin combinations without departing from the purpose of the present invention. It doesn't matter if you stay there. In carrying out the present invention, in order to obtain an injection molded article before being subjected to mat processing, powders or pellets of the above-mentioned specific thermoplastic polyester resin and other resins to be blended are mixed in a mixer and then extruded. Either method can be used, such as pelletizing the resin powder and then using a normal injection molding machine to make the desired molded product, or directly feeding these resin powders or pellets to an injection molding machine to make the desired molded product. Any ordinary injection molding method may be used. Note that the injection molded product in the present invention is not substantially subjected to so-called biaxial stretching treatment. The polyester injection molded product having a matte pearlescent luster of the present invention is obtained by injection molding as described above, and then sandblasting the molded product using an abrasive with a particle size of 300 μm or less or coating it with a matting agent with a particle size of 10 μm or less. This material has been treated with pine wood according to the method. As the abrasive used in the sandblasting method, iron powder, glass beads, corundum, etc. are used. If the particle size of these abrasives is too large, the surface of the molded product will become rough and the appearance will be poor.
or more (300μ or less), more preferably #100 or more (150μ or less). As the sandblasting method, any conventional method may be used as appropriate. Next, the coating method will be described. Spray coating in which a paint containing a matting agent is sprayed onto the molded article, printing coating by a printing method, roll coating by a roll, other dipping methods, flow coating, etc. can be used as appropriate. Various matting agents can be used, but fine white carbon with a particle size of 10 μm or less, titanium oxide, alumina, barium sulfate, magnesium sulfate, etc. are preferable. Any paint can be used as long as it is transparent, adheres well to polyester resin, and has good weather resistance. The injection molded product of the present invention that has been subjected to the matte processing described above has an unprecedented elegance and solid feel,
It has a high-quality matte pearl luster with a good surface appearance and is excellent in decorative properties. The present invention will be specifically explained below using Examples. Examples 1 to 26, Comparative Examples 1 to 8 Polyethylene terephthalate (hereinafter abbreviated as PET), polymethyl methacrylate (hereinafter PMMA)
It is abbreviated as ), polyethylene (hereinafter abbreviated as PE), polypropylene (hereinafter abbreviated as PP), polystyrene (hereinafter abbreviated as PSt), and polyethylene-ethyl acrylate copolymer (hereinafter abbreviated as PEEA).
The resin composition blended in the proportion shown in the table is L/D=22
Extrude into strands using a 40mm extruder at a resin temperature of 280℃, cool, cut into 4mm lengths to form pellets, and then dry in a rotary vacuum dryer to 1mm.
The pellets were dried for 6 hours at 150° C. under a Hg vacuum to obtain dried pellets having various composition ratios. These various pellets were processed using a Meiki Seisakusho SJ-40C injection molding machine at a resin temperature of 280℃ and an injection pressure of 30Kg/cm ² (gauge pressure).
Injection molded under the following conditions: molding cycle 37 seconds, mold temperature 20℃, hot runner system, total length 60mm, body outside diameter 50mm, mouth thread outside diameter 48mm (wall thickness 25mm), body wall thickness 3.0mm. I got a cream container. All of these cream containers exhibited pearl-like surface gloss. These cream containers were then subjected to matte processing under the sandblasting conditions shown in Table 1.
The pine-finished container had an elegant and dignified appearance. Table 1 shows the evaluation results of the container surface appearance.
Comparative examples are also shown. The surface appearance judgment display is as follows. These indications are common to the following examples and comparative examples. ◎: Very elegant and profound ○: Elegant and profound △: Elegant but somewhat lacking in profound feeling ×: Very elegant and profound in feeling

【table】

[Table] Examples 27 to 37, Comparative Examples 9 to 11 Dry pellets were obtained from resin compositions blended in various proportions shown in Table 2 in the same manner as in Examples 1 to 26. These pellets were molded using a Nippon Steel N-140B injection molding machine at a resin temperature of 275℃ and an injection pressure of 50Kg/cm ^2.
(gauge pressure), molding cycle 35 seconds, mold temperature 20
℃, injection molded under hot runner system conditions, total length 16 mm, body outer diameter 52 mm, mouth thread outer diameter 52 mm.
(wall thickness: 2 mm), and a bottle cap with a body wall thickness of 2 mm was obtained. All of these caps had a pearly surface gloss. These caps were then subjected to matte processing according to the conditions of the coating method (spray painting) shown in Table 2. In order to disperse the matting agent well in the paint, it was thoroughly kneaded overnight in a roll mill. Table 2 shows the evaluation results of the surface appearance of these matte-treated molded products, together with comparative examples.

【table】

【table】

Claims (1)

[Claims] 1 50 to 95% by weight of a thermoplastic polyester resin whose main repeating unit is ethylene terephthalate and an intrinsic viscosity of 0.75 to 1.40, and at least one selected from the group consisting of a methacrylic resin, a saturated aliphatic olefin resin, and a styrene resin. An injection molded product made of a blend of 5 to 50% by weight of a resin composition is polished to a matte finish by sandblasting using an abrasive with a particle size of 300μ or less or by a coating method using a matte agent with a particle size of 10μ or less. Polyester injection molded product with a pearlescent luster.