JP2001269978A - Method for manufacturing thermoplastic resin molded product and thermoplastic resin molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a pearl tone or metallic tone thermoplastic resin molded product which does not generate molding defects such as welds or uneven flows of the surface of the product, in the injection or the extrusion molding, and the thermoplastic resin molded product. SOLUTION: A flaky pigment: 0.1-5 wt.%, at least one of a fibrous filler: 0.1-50 wt.% or an acicular filler: 0.1-50 wt.% and a foaming agent: 0.01-5 wt.% are blended into the thermoplastic resin: 50-95 wt.%. When the obtained composition of the thermoplastic resin is injected or extruded, the heat cycle molding method that the surface temperature of the cavities of the metal molds goes up and down repeatedly is applied. By this method, the molded product without the welds or uneven flows can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic resin molded article and a thermoplastic resin molded article.
Molding by injection molding or extrusion molding using a thermoplastic resin composition containing a plate-like filler (plate-like pigment), such as a pearl color pigment made from mica or a metallic pigment made from aluminum flakes The present invention relates to a method for producing a thermoplastic resin molded product suitable for obtaining a product and a thermoplastic resin molded product.

[0002]

2. Description of the Related Art Conventionally, injection molding or extrusion is performed using a thermoplastic resin composition containing a plate-like filler, such as a pearl pigment using mica as a raw material or a metallic pigment using aluminum flake as a raw material. The molding is performed to obtain a pearl-like or metallic-like molded product.

[0003]

Injection molding using a thermoplastic resin composition containing a plate-like filler, such as a pearl pigment using mica as a raw material or a metallic pigment using aluminum flake as a raw material. Alternatively, when extrusion molding is performed, a line (weld) clearly appearing as a joined portion appears at a portion where the molten resin is associated. In addition, unevenness of the flow appears downstream. This is generally said to be because the plate-like fillers are oriented upright with respect to the product surface at the weld portion, and the plate-like fillers appear darker at other portions where the plate-like fillers are oriented parallel to the product surface.

However, a close observation shows that there is a transparent portion containing no filler (or a small content) in the weld portion, which emphasizes the weld, and that the flow unevenness does not contain the filler (or contains no filler). It was found that the transparent portion (small amount) had a river shape and was seen to flow on a plane having a high filler concentration.

[0005] Thermoplastic resin compositions containing plate-like fillers such as pearl pigments and metallic pigments are useful surface decorating means for increasing the commercial value, but have the drawbacks described above, and thus are not applicable. The shape of moldings that can be formed has been limited.

The present invention relates to a pearl-like or metallic-like thermoplastic resin molded product or a thermoplastic resin molded product without sink marks and pock which does not cause defects such as welds or uneven flow on the surface of the molded product in injection molding or extrusion molding. It is an object of the present invention to provide a method for producing a product and a thermoplastic resin molded product.

[0007]

The present invention has solved the above-mentioned problems as follows. That is, thermoplastic resin: 50
To 95% by weight, plate-like pigment: 0.1 to 5% by weight, fibrous filler: 0.1 to 50% by weight, and needle-like filler: 0.1
-50% by weight and at least one foaming agent.
When the obtained thermoplastic resin composition is subjected to injection molding or extrusion molding, the thermoplastic resin is subjected to a heat cycle molding method in which the temperature of the cavity surface of the mold is repeatedly increased and decreased. A molded article is formed. This makes it possible to obtain a molded article free of weld and uneven flow.

[0008] Further, a blowing agent: 0.01 to
5% by weight, and when the obtained thermoplastic resin composition is subjected to injection molding or extrusion molding, a thermoplastic resin molded product is applied by applying a heat cycle molding method in which the temperature of a cavity surface of a mold is repeatedly increased and decreased. Molding. This makes it possible to obtain a molded product without sink marks and pock.

[0009]

Embodiments of the present invention will be described with reference to the drawings.

When performing injection molding or extrusion molding using a thermoplastic resin composition containing a plate-like filler such as a pearl pigment or a metallic pigment, for example, as shown in FIG. If there is an obstacle like hole 1 in
Weld 2 appears downstream of it. As shown in FIG. 2, which is a cross-sectional view taken along the line AA in FIG. 1, in a cross section near the hole 1, the plate-like filler stands upright on the surface of the molded product at a weld portion,
The transparent layer 3 is formed in the middle. The color tone of these portions is recognized as a weld because the plate-like filler is different from the other portions oriented along the surface of the molded product.

The transparent layer 3 is formed, as shown in FIG.
It is considered that there is a fluidized bed, and after the molten resin is associated, the fluidized bed is cooled and solidified as it is, and since this fluidized bed does not contain (or has little) plate-like filler, it is considered to be a transparent layer.

Further, as shown in FIG. 4 which is a cross-sectional view taken along the line BB of FIG. 1, an inverted triangular transparent layer 3 is observed in a portion observed as uneven flow downstream of the weld 2. This is presumably because the transparent layer 3 shown in FIG. 2 was extruded on the surface of the molded product while being pushed in the flow direction of the molten resin.

The applicant of the present invention has previously filed Japanese Patent Application No. 2000-01558.
According to No. 8, when a fibrous filler such as glass fiber or a needle-like filler such as potassium titanate is added to a plate-like filler such as a pearl pigment or a metallic pigment and blended into a resin, Although it has been disclosed that the disadvantages are reduced, it has been found that there is still room for improvement.

Thus, the present inventors have conducted intensive research and have found that
Thermoplastic resin: 50 to 95% by weight, plate-like pigment: 0.1
To 5% by weight, fibrous filler: 0.1 to 50% by weight, and acicular filler: at least one of 0.1 to 50% by weight
Heat cycle molding in which a seed and a foaming agent: 0.01 to 5% by weight are blended and the temperature of a cavity surface of a mold is repeatedly increased and decreased when injection molding or extrusion molding of the obtained thermoplastic resin composition. It has been found that by applying the method, it is possible to obtain a molded article having a smooth surface and no weld or uneven flow.

That is, the transparent layer 3 at the weld portion as shown in FIG. 2 and the transparent layer 3 at the uneven flow portion as shown in FIG.
Disappears. This is considered to be because foaming occurs at the flow front of the molten resin flowing in the mold, so that the Fonten flow as shown in FIG. 3 is prevented.

Further, a plate-like filler as shown in FIG.
The orientation of the fibrous filler and the acicular filler is also relaxed and less noticeable. This is probably because the orientation of the plate-like filler, the fibrous filler, and the needle-like filler is disturbed by foaming at the flow front.

As a means for obtaining a smooth surface by using a foaming raw material, there is a counter pressure method. In this method, the inside of the cavity is pressurized and foaming of the molten resin at the flow front is suppressed. Such effects do not appear.

When a foaming raw material is used in ordinary injection molding or extrusion molding, traces of foaming appear on the surface of the molded product. However, by applying the heat cycle molding method, the surface becomes smooth, and weld and uneven flow are observed. Surface defects can be described.

The heat cycle molding method is a method in which the temperature of the mold is increased when the molten resin is charged into the mold, and the temperature of the mold is lowered after the filling is completed, and the molded product is taken out.

As the heat cycle molding method, many methods have been proposed, such as a method of passing a heating and cooling medium near the cavity surface, and a method of using an electric heater or high frequency to heat the cavity surface.

When a thermoplastic composition containing a plate-like pigment, a fibrous filler, a needle-like filler and the like is injection-molded or extruded, a heat cycle molding method is applied to smooth the surface, and ribs and bosses are formed on the back surface. Some areas may start to show sink marks or seemingly sink marks, which can be eliminated by adding a blowing agent.

In addition, when a thermoplastic resin composition containing long fibers is injection-molded or extruded, a heat cycle molding method is applied to make the surface smooth and a pock or seemingly pock-like pattern may begin to appear. However, the addition of a blowing agent also eliminates it.

In the above embodiment, a thermoplastic resin containing plate-like pigments, fibrous fillers, needle-like fillers and the like has been described. However, sinkage may occur during injection. As a countermeasure, a foaming agent is added, but the surface is roughened by foaming, so that the use of the product is limited. However, when the heat cycle molding method is applied to this, the surface becomes smooth, and the surface quality of the molded product is improved.

Examples of the raw material resin applicable to the present invention include vinyl chloride resin (hard and soft resin composition, the same applies hereinafter), acrylate resin (acrylic acid and methacrylic acid as acid, methyl as alkyl group, etc.). Group, ethyl group, etc.), styrene resin (general, high impact, etc.),
Amorphous resins such as acrylonitrile-styrene resin, acrylonitrile-styrene-butadiene resin, modified polyphenylene oxide, polycarbonate, polysulfone, polyarylate, polyetherimide, and polyethersulfone; polyethylene resins (low-density,
Linear low density, medium density, high density, etc.), polypropylene resin (homopolymer, random polymer, block polymer, etc.), polybutene-1, polymethylpentene
1. Fluorine resin (polyvinylidene fluoride etc.), polyoxymethylene, polyamide resin (6, 66 etc.), terephthalic acid ester resin (polyethylene terephthalate, polybutylene terephthalate etc.), polyphenylene sulfide, polyether ether ketone , Polyether ketone, crystalline resin such as polyimide, liquid crystal polymer (aromatic polyester type, aromatic polyester amide type, etc.), polyvinyl alcohol, polylactic acid (trade name Laceia, Lacty, etc.), fatty acid polyester type resin (product) Bionale), Plaxel, Cell Green, etc.), a copolymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid (trade name: Biopol, etc.), or a mixture or inclusion, terephthalate-based resin (as ester group) , Ethi , Butylene, etc.), thermosetting resins such as epoxy resin, melamine resin, phenolic resin, urea resin, unsaturated polyester resin, urethane resin, silicone resin, alkyd resin, and alloys thereof. Filler compounds (granular fillers such as talc, fibrous materials such as glass fibers) and the like.

The plate-like pigment (plate-like filler) includes a pearl pigment and a metallic pigment. Examples of the pearl pigment include those obtained by treating glass flakes in a pearl-like surface, in addition to those using mica or the like as a raw material. Metallic pigments include those obtained by subjecting glass flakes to a metallic surface treatment, in addition to those using aluminum flakes as a raw material.

The fibrous filler includes various inorganic fibers such as glass fibers, various organic fibers such as aramid fibers, and carbon fibers.

The acicular filler includes a whisker such as potassium titanate and a mineral acicular filler such as wollastonite.

The foaming agents include organic foaming agents such as azo, nitroso and sulfonylhydrazide, inorganic foaming agents such as sodium heavy carbon, and physical foaming agents such as water and chlorofluorocarbon.

In the injection molding method, in addition to a normal injection molding method, an injection compression method, a local vibration / pressing method, a gas press method,
Gas assist method, hollow molding method, sandwich molding method, 2
Color molding method, in-mold molding method, push-pull molding method,
Including high-speed injection molding.

The extrusion molding method includes a blow molding method and a sheet molding method.

[0031]

According to the present invention, it is possible to obtain a molded article having no weld or uneven flow in injection molding or extrusion molding in a pearl or metallic tone.

Further, in injection molding or extrusion molding containing or not containing plate-like pigments, fibrous fillers and needle-like fillers, it is possible to obtain molded articles without sink marks and pock.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which welds and uneven flow appear due to obstacles in a flow path of a molten resin when injection molding or extrusion molding is performed using a thermoplastic resin composition containing a plate-like filler.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an explanatory view of forming a transparent layer shown in FIG. 2;

FIG. 4 is a sectional view taken along line BB of FIG. 1;

[Explanation of symbols]

 1 hole (obstacle) 2 weld 3 transparent layer 4 Fontenflow

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 7/04 C08K 7/04 C08L 101/00 C08L 101/00 // B29K 101: 12 B29K 101: 12 105 : 04 105: 04 105: 16 105: 16 (72) Inventor Masahiko Yamaki 2-1-1 Tango-dori, Minami-ku, Nagoya City, Aichi Prefecture Inside Mitsui Chemicals, Inc. (72) Inventor Akihiko Imagawa Tango-dori, Minami-ku, Nagoya City, Aichi Prefecture 2-chome No. 1 Mitsui Chemicals Co., Ltd. F-term (reference) 4F074 AA97A AC02 AC23 AC34 AE04 AG01 AG06 BA03 BA13 BA14 BA15 BA18 CA22 CA26 CC04X CC04Y CC22X CC32X 4F206 AA03 AA13 AA15 AA21 AB02 AB12 AB25 AG20 AM34 J02 AM34 JM05 JN21 4F207 AA13 AA15 AA21 AB02 AB11 AB12 AB16 AF05 AF09 AG20 AK01 AK02 AM36 KA01 KA11 KF04 KK45 4J002 AA011 DA017 DE187 DL187 EQ018 ES008 EV288 FA047 FA067 FD0 17 FD096 FD328

Claims (5)

[Claims] 1. A thermoplastic resin: 50 to 95% by weight, a plate-like pigment: 0.1 to 5% by weight, and a fibrous filler: 0.1 to 5% by weight.
50% by weight, at least one of needle fillers: 0.1 to 50% by weight and a foaming agent: 0.01 to 5% by weight, and the obtained thermoplastic resin composition is subjected to injection molding or A method for producing a thermoplastic resin molded article, comprising: applying a heat cycle molding method that repeatedly raises and lowers the temperature of a cavity surface of a mold during extrusion molding. 2. The method according to claim 1, wherein the plate-like pigment is a pearl pigment. 3. The method according to claim 1, wherein the plate-like pigment is a metallic pigment. 4. A method in which a foaming agent: 0.01 to 5% by weight is blended with a thermoplastic resin, and the temperature of the cavity surface of the mold is repeated when injection molding or extrusion molding of the obtained thermoplastic resin composition. A method for producing a thermoplastic resin molded product, wherein the thermoplastic resin molded product is molded by applying a heat cycle molding method that goes up and down. 5. A thermoplastic resin molded article produced by the production method according to claim 1.