JPH07119047B2 - Manufacturing method of patterned foam molding - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a foamed molded article having a pattern.

2. Description of the Related Art Conventionally, a molded product having a pattern of wood grain or the like on the surface of a foamed molded product having a low expansion ratio has been used in various fields as a substitute for wood or the like.

This type of foamed molded article is formed by continuously extruding and foaming a composition in which a foaming agent is mixed with a base resin such as polyvinyl chloride, and then painting, printing, sheeting or embossing online or offline. It is manufactured by performing the above. However, in such a conventional method, not only additional post-processing is required, but also the patterned surface layer part is peeled off due to temperature change or moisture absorption due to construction work and outdoor exposure after construction. There is a problem of disappearing.

In addition, relatively recently, the method of putting wood grain or marble pattern on the surface layer part of the low-foam molded article by using a special structure for the tip of the extruder screw or die head has come to be used. However, not only does it require a foam molding machine with a special structure, but the pattern is formed by simple physical irregularities, curves and / or straight lines, etc. It is difficult to make them appear.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention solves the above-mentioned problems of the conventional method for producing a foamed molded article with a pattern, and has a surface layer portion in which a variety of complicated patterns having excellent fastness and weather resistance are revealed. It was made to provide a foamed molded article with a pattern.

Means for Solving the Problem That is, the present invention, the surface layer acrylic resin composition containing a flake-like powder for decoration of particle diameter 230 ~ 1,400μ and the inner layer thermoplastic resin composition containing a foaming agent separately The present invention relates to a method for producing a foamed molded article with a pattern, which comprises co-extruding in a molten state into a metal mold using the extruder and performing low-foam integral molding in the metal mold.

The flaky powder for decoration used in the present invention includes flaky inorganic powder (for example, mica powder, talc powder, calcium carbonate powder, etc.), metal powder (for example, aluminum powder, copper powder, etc.), synthetic resin powder ( For example, colored powders of thermosetting resins (epoxy resin, unsaturated polyester resin powders, etc.) and the like are exemplified, but mica capable of showing various patterns such as wood grain pattern and embossed pattern is particularly preferable.

As this type of mica, Suzolite Mica 60-S,
Examples include 40-S, 150S, 20-S (Kuraray Co., Ltd. commercial product), Clarite mica 80-C, 60-C, 30-C (Kuraray Co., Ltd. commercial product).

The particle size of the flaky powder (weight average frame diameter) is usually 230
~ 1,400μ, preferably 280 ~ 650μ, and if it is 650μ or more, it will clog the extrusion slit and cause discharge failure, and in the case of 230μ or less, wood grain or embossed pattern is sufficient on the surface layer of the low foam molded article. It does not work.

The content of the flaky powder is usually 3 to 25% by weight, preferably 5 to 15% by weight. When the amount is 3% by weight or less, it is difficult to obtain the desired pattern on the surface layer of the low foam molded article. Also, 25% by weight
When it becomes the above, it will become easy to exfoliate from the surface layer part, and it will become difficult to pelletize the acrylic resin composition for surface layers.

Depending on the type of flaky powder, various patterns can be developed on the surface layer of the low-foam molded product. For example, when mica powder is used, a wood grain or embossed pattern can be obtained as described above, but a granite pattern can be obtained by using aluminum powder or thermosetting resin powder.

If desired, the flaky powder may be used in combination of two or more kinds.

As the acrylic resin to be mixed with the above flaky powder,
Polymethylmethacrylate, methylmethacrylate-
Butyl acrylate copolymer, methyl methacrylate-
Examples thereof include polymers and copolymers of methacrylic acid esters such as styrene copolymers, and particularly preferable ones are acrylic polymers having a melt index (230 ° C., 3.8 kg) of 1.0 to 10.0, preferably 3 to 8 Resin, eg Acrypet VH
S, Acrypet MGS, Acrypet MD, Highpet HBS
(Both are commercial products manufactured by Mitsubishi Rayon Co., Ltd.)
These resins impart excellent weather resistance that prevents economical discoloration and deterioration to the patterned foamed molded article.

Examples of the thermoplastic resin for the inner layer used in the present invention include polyvinyl chloride, ABS resin, AS resin, AAS resin, polycarbonate, acrylic resin and the like.

Foaming agents for thermoplastics such as polyvinyl chloride, for example,
A solid foaming agent such as sodium bicarbonate, ammonium carbonate, azodicarboxylic acid amide, benzenesulfonyl hydrazide is appropriately added (usually 0.3 to 3.0% by weight).

The above acrylic resin composition for the surface layer and the thermoplastic resin composition for the inner layer are usually formed into pellets in advance,
It is subjected to the following coextrusion molding process.

As the coextrusion molding apparatus, those conventionally used in the production of plastic coextrusion molded articles may be appropriately used, but a particularly suitable apparatus is a single layer for extruding the surface layer acrylic resin composition. A modified extrusion die for a selka process, comprising an extruder and a conical twin extruder for extruding a thermoplastic resin composition for an inner layer.

In this case, the slit width of the extruder for extruding the inner layer composition is not particularly limited (usually 0.5 to 3.0 mm), but the slit width of the extruder for extruding the surface layer composition is practically 0.3 to 0.6
mm.

When the slit width of the latter is 0.3 mm or less, flaky powder is apt to be clogged in the slit to cause discharge trouble, and when it is 0.6 mm or more, it is difficult to reveal a pattern with unevenness. Becomes In this case, by blending a large amount of flaky powder, it is possible to make the slit width 0.6 mm or more without losing the pattern having unevenness, but for the reasons described above, the amount of flaky powder blended. 25% by weight
Since it is difficult to achieve the above, the slit width cannot be increased so much.

The extrusion temperature may be appropriately selected depending on the type of base resin of the composition to be treated, etc., but is usually 180 to 220 ° C.

The inner layer composition extruded in a molten state from the extruder foams when discharged into the mold, and heat-bonds with the surface layer composition extruded in a molten state from another extruder to give a predetermined form. Is integrally molded into. In this case, if the surface layer is too thin, the flaky powder is likely to be peeled off. Therefore, the surface layer thickness is preferably set to about 100 to 300 μm by adjusting the take-up speed of the integrally molded body.

The extrusion rate and the take-up speed are not particularly limited, but are usually 50 to 100 kg / hr and 0.5 to 1.5 m / min, respectively.

The expansion ratio of the inner layer is usually 1.5 to 3.0.

Hereinafter, the present invention will be described with reference to examples.

Example 1 A resin composition in which 5 g of mica powder (“Szolite Mica 60-S” manufactured by Kuraray Co., Ltd.) was uniformly dispersed in 95 g of acrylic resin (“Acrypet MGS-60” manufactured by Mitsubishi Rayon Co., Ltd.) Extruded into pellet form (Dimension: 2φ
× 3mm).

On the other hand, a powdery resin composition was prepared by dry blending a composition in which 1.5 wt% of sodium bicarbonate was mixed with polyvinyl chloride (average degree of polymerization: 700).

As the co-extrusion apparatus, a profile extrusion die for the selka process equipped with a 45 mm conical twin extruder and a 30 mm (or 40 mm) single extruder was used.

By supplying the above-mentioned surface layer pellets and inner layer powder resin composition into a single extruder and a conical twin extruder, respectively, and performing co-extrusion molding according to a conventional method, low-foam molding in which mica powder is embossed on the surface. A body (density: 0.55 g / cm ³ , surface layer thickness: 0.15 mm, inner layer thickness: 7.0 mm) was produced.

The co-extrusion molding conditions are as follows: Extrusion temperature: 200 ° C Retention time of extruder: 8 minutes Screw rotation speed: 25r.pm Extrusion rate: 50kg / hr Retention time in barrel: 3 minutes Effect of the invention The foamed molded product with a pattern provided by is excellent in robustness and weather resistance, and the surface layer part and the low foaming inner layer part in which complicated and diverse patterns are revealed are integrated by heat fusion,
Although it is particularly suitable as a building exterior material, it can be generally used in other fields such as interior building materials, furniture and fixtures such as tableware.

Claims (3)

[Claims] 1. An acrylic resin composition for a surface layer containing a flaky powder for decoration having a particle size of 230 to 1,400 μ and a thermoplastic resin composition for an inner layer containing a foaming agent are melted using separate extruders. A process for producing a foamed molded article with a pattern, which comprises co-extruding into a mold in a state and performing low foaming integral molding in the mold. 2. The method according to claim 1, wherein the flaky powder is mica powder. 3. A foamed molded article having a pattern obtained by the method according to claim 1.