JP7420641B2 - Molded object - Google Patents

Description

The present invention relates to a molded article of a resin composition containing fibers and a thermoplastic resin.

Fiber-reinforced molded bodies have been well known. Adding fiber to the matrix resin has the advantage of increasing physical properties such as strength. It is also known to reuse fiber waste as reinforcing fibers. Patent Document 1 discloses that waste plastic made of a specific synthetic resin material or a plurality of waste plastic groups made of a plurality of different synthetic resin materials are mixed with thermosetting resin, wood chips, fiber waste, etc. It has been proposed to perform molding processing. Patent Document 2 proposes molding a resin fastener by mixing synthetic fibers with an average fiber length of 0.1 to 6 mm into a flexible thermoplastic resin. Patent Document 3 proposes molding recycled resin parts by mixing fiber waste, wood fibers, glass fibers, reinforcing fibers such as talc into waste low-density polyethylene resin. Further, Patent Document 4 proposes that a resin composition is extruded into a core material and the surface is sanded to give a woody appearance.

Japanese Patent Application Publication No. 2006-305802 Japanese Patent Application Publication No. 2004-346954 Japanese Patent Application Publication No. 2003-261689 Japanese Patent Application Publication No. 2000-141326

However, with the above-mentioned conventional technology, the fibers deteriorate due to heat during the mixing process and/or the molding process, resulting in deterioration of the physical properties of the molded product and the appearance quality, and it is difficult to achieve the texture and appearance of the fabric. However, further improvements were required.

In order to solve the above-mentioned conventional problems, the present invention provides a molded article that prevents fiber deterioration, has high physical properties and appearance quality, and has a fabric feel and appearance.

The molded article of the present invention is a molded article of a resin composition containing fibers and a thermoplastic resin, wherein the fibers are cotton fiber waste that has been scoured and/or bleached , and the thermoplastic resin has a melting point of 120 to 120. The temperature is 200° C., and the surface of the molded body is polished to expose the fibers.

The molded article of the present invention is a molded article of a resin composition containing fibers and a thermoplastic resin, the fibers being natural fibers, the thermoplastic resin having a melting point of 120 to 200°C, and the molded article having a melting point of 120 to 200°C. Since the surface is polished and the fibers are exposed, deterioration of the fibers can be prevented, the physical properties of the molded article can be maintained at high levels, and a fiber-reinforced molded article with a high quality appearance can be provided. In addition, the surface is polished and the fibers are exposed, resulting in a smooth touch and a good appearance. That is, it is possible to provide a molded article having a fabric-like feel and appearance.

FIG. 1A is a schematic perspective view of a coated molded body according to an embodiment of the present invention, and FIG. 1B is a sectional view thereof. FIG. 2 is an enlarged photograph (magnification: 40) of the surface of the coated molded article of Example 1 of the present invention. FIG. 3 is an enlarged photograph (magnification: 40) of the surface of the coated molded article of Example 2 of the present invention. FIG. 4 is an enlarged photograph (magnification: 40) of the surface of the coated molded article of Example 3 of the present invention. FIG. 5 is an enlarged photograph (magnification: 40) of the surface of the coated molded product of Comparative Example 1.

The molded article of the present invention includes fibers and a thermoplastic resin, the fibers being natural fibers, and the thermoplastic resin having a melting point of 120 to 200°C. By selecting natural fibers as the fibers and selecting and combining them with a thermoplastic resin with a specific melting point as the matrix resin, the present invention suppresses thermal deterioration of the fibers in the mixing process of the fibers and resin and/or the molding process, and improves the appearance of the fibers. A high-quality molded body can be obtained. In addition, the surface of the molded product is polished and the natural fibers are exposed, so it is soft to the touch and has a good appearance. In the case of a coated molded article, the thickness of the coating layer before polishing is preferably 1 to 5 mm, more preferably 2 to 3 mm, and the thickness of the coating layer after polishing is preferably 0.5 to 4.5 mm. More preferably, it is 1.5 to 2.5 mm.
The exposure of natural fibers can be confirmed using a surface observation microscope.

The average fiber length of the natural fibers is preferably 1 to 20 mm, more preferably 2 to 18 mm, and even more preferably 3 to 15 mm. Within the above range, it is easy to mix uniformly with the thermoplastic resin of the matrix resin. Natural fibers include plant fibers and animal fibers. Plant fibers include cotton, hemp, kapok, palm fiber, sisal fiber, banana fiber, coconut fiber, bamboo fiber, etc., and animal fibers include wool, goat hair, cashmere, mohair, Angora, alpaca, camel hair, and silk are available, but cotton is preferred from the viewpoint of cost and stable supply.

The addition ratio of the natural fiber is preferably 5 to 55% by weight, more preferably 7 to 50% by weight, and still more preferably 20 to 40% by weight, when the total of fibers and thermoplastic resin is taken as a parameter. be. If it is within the above range, the reinforcing effect of the molded body will be higher, and the fibers will be more likely to be exposed by polishing.

The natural fiber is preferably cotton. Cotton has a high affinity with thermoplastic resins and has a high reinforcing effect on molded objects. The natural fibers are preferably fiber waste generated during the manufacturing process of cotton products. Process waste includes various process waste, such as fiber waste generated in the raising process, fiber waste generated in the cutting process, and fiber waste generated in the curling process. In addition, fiber waste obtained by opening and recycling old clothes can also be used. Conventionally, such waste has been discarded, but collecting and reusing it has the advantage of effectively utilizing resources. Cotton fiber waste that has undergone a scouring and/or bleaching process has a high degree of whiteness and is therefore preferable. If the whiteness of the fiber waste is high, the base color will be stabilized when colored with a coloring agent during molding, and coloring unevenness will be reduced.

The thermoplastic resin is preferably a polyolefin resin because of its good moldability. Examples of polyolefin resins include polyethylene resin, polypropylene resin, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA) resin, ionomer resin, ethylene-vinyl alcohol copolymer, ethylene-vinyl chloride copolymer, Alternatively, a blend of these resins can be used. In addition to polyolefin resins, ABS resins and the like can be used.

It is also possible to construct the molded body from a resin to which fibers are added without using a core material. It is also possible to use a two-layer extruded resin with fibers added to the covering portion.

The material of the core material is not particularly limited. Materials such as metal, resin, and wood can be selected depending on the situation. If strength is required, it is preferable to use metal for the core material. When the core material is metal, aluminum is preferred. This is because it is superior in terms of strength, precision, and weight. Preferred other metals include iron, stainless steel, copper, and various alloys. Any shape can be used, such as a plate, hollow body, or pipe. It can be applied to materials used in housing construction materials, furniture, shelves, warehouse walls, etc. In the present invention, "made of aluminum" also includes "made of aluminum alloy", and the same applies to other metals.

Preferably, an adhesive layer is present between the core material and the covering layer. As the adhesive, for example, a resin containing an epoxy group-containing polyolefin can be used. The thickness of the adhesive layer is preferably 50 to 300 μm, more preferably 100 to 200 μm.

The molded article of the present invention can be manufactured by the following steps.
(1) A resin composition containing fibers and a thermoplastic resin is heated to a temperature higher than the melting point of the thermoplastic resin, melted and kneaded to form a compound, and then cooled and granulated or crushed to form pellets.
(2) The pellets are melted and molded into a predetermined shape by extrusion or the like.
(3) After cooling, the surface of the product is polished to expose the fibers.

The coated molded article of the present invention can be manufactured by the following steps.
(1) A resin composition containing fibers and a thermoplastic resin is heated to a temperature higher than the melting point of the thermoplastic resin, melted and kneaded to form a compound, and then cooled and granulated or crushed to form pellets.
(2) The pellets are melted and extruded onto the surface of the core material to form a coating layer.
(3) After cooling, the surface of the coating layer is polished to expose the fibers.

In the kneading process, a kneader or other kneader is used to mix natural fibers and thermoplastic resin into a compound (mixture) at a temperature higher than the melting temperature of the resin, and this compound is extruded and granulated or crushed to form pellets. do. The pellets can be used as a masterbatch and additional resin can be added during molding.

In the compounding step and/or molding step, additives such as colorants, various stabilizers, dispersants, and compatibilizers may be added.
Any color can be used as the colorant. Examples of the coloring agent include pigments, coloring masterbatches, dry colors, paste colors, liquid masterbatches, and the like.
Examples of the stabilizer include a heat stabilizer, an antioxidant, a light stabilizer, a surfactant, and the like.
Examples of the compatibilizing agent include unsaturated carboxylic acids. Examples of unsaturated carboxylic acids include unsaturated monocarboxylic acids and unsaturated dicarboxylic acids, with unsaturated dicarboxylic acids and their anhydrides being particularly preferred, such as maleic acid and maleic anhydride.
By changing the color of the colorant, a molded article of any color tone can be obtained. The content of the colorant is preferably 3 to 5% by weight based on the polyolefin resin.

In the polishing step, it is preferable to polish the surface of the coating layer in one direction. For polishing, sanding using sandpaper or brushing using a brush is preferable. The sandpaper preferably has a grit of 24 to 120. Although heat may be generated during the sanding process, deterioration of the resin can be prevented because the melting point of the thermoplastic resin is 120 to 200°C.

This will be explained below using the drawings. In the following, the same reference numerals indicate the same items. FIG. 1 is a schematic perspective view of a coated molded body 1 according to an embodiment of the present invention, and FIG. 1B is a sectional view thereof. This coated molded body 1 has an adhesive layer 3 and a covering layer 4 formed on the surface of a core material 2 by integral extrusion molding. The core material 2 is hollow aluminum, and the surface of the covering layer 4 is sanded in one direction.

The present invention will be specifically described below using Examples. Note that the present invention is not limited to the following examples.

(Example 1)
<Core material>
As the core material 2 shown in FIGS. 1A and 1B, an aluminum hollow material for building materials, outer diameter of 30 mm vertically, 50 mm horizontally, 1.2 mm thick, and 1 m long (rectangular cross section, 2 hollow parts) was used.
<Coating material>
(1) Fiber Cotton fiber waste (raised fiber waste) that had undergone a scouring and bleaching process was used. The average fiber length was 2.0 mm.
(2) Resin Polypropylene resin (PP) with a melting point of 160°C was used. This resin had a melt flow rate (MFR) of 30 g/10 min at 190° C. and 2.16 kgf.
(3) Compound-pellet 60 parts by weight of PP, 40 parts by weight of fiber waste, and 5.0 parts by weight of blue colorant were weighed, melted and kneaded in a kneader heated to 190°C, extruded, and cooled. It was ground and pelletized. When the total of fiber waste and thermoplastic resin was taken as a parameter, the fiber waste was 40% by weight.
<Adhesive layer material>
The following adhesive was used as an epoxy group-containing polyolefin resin on the surface of the core material 2.
Bond First (registered trademark) 7B (manufactured by Sumitomo Chemical Co., Ltd., ethylene-glycidyl methacrylate-vinyl acetate (copolymerization ratio (weight ratio) 83:12:5), melt flow rate at melting point 95°C, 190°C, 2.16 kgf (MFR)7g/10min)
<Extrusion coating molding>
An integral extrusion molded body was manufactured using a coextrusion type integral extrusion molding machine. The adhesive layer material and the coating layer material pellets are extruded simultaneously from an extruder, and are laminated and coated on an aluminum core material in a die to form an adhesive layer and coating on the entire outer surface of the aluminum core material in the circumferential direction. A monolithic extrusion molded body having layers was produced. The extrusion conditions and core material conditions are as follows.
・Extruder: 40mm diameter, single screw extruder (extrusion temperature approximately 190℃)
・The aluminum core material was preheated (approximately 100°C) immediately before being inserted into the die.
- The thickness of the adhesive layer of the obtained coated molded body after cooling was 200 μm, and the thickness of the coating resin was 1.5 mm.
<Polishing>
The surface of the coated molded body was polished with a belt sander. The sandpaper count and polishing method are as follows.
・Sandpaper count: #40 (Sandpaper C40: silicon carbide abrasive)
・Paper speed: 13m/min
・Molded body feeding speed: 8m/min
Moreover, the thickness of the coating resin after polishing was 1.0 mm.
As a result of the above, a coated molded article with a smooth appearance and touch, and a fabric feel was obtained. The obtained coated molded body is shown in FIGS. 1A and 1B and FIG. 2 (surface photograph, magnification: 40 times).

(Example 2)
During polishing, #34 (sandpaper 784F: containing 50% ceramic abrasive) was used as sandpaper, followed by #60 (sandpaper C60: silicon carbide abrasive). The same procedure as in Example 1 was carried out except for the points mentioned above. The obtained coated molded article is shown in FIG. 3 (surface photograph, magnification: 40 times).

(Example 3)
During polishing, sandpaper #34 (sandpaper 784F: containing 50% ceramic abrasive material) was used, and then #60 (sandpaper C60: silicon carbide abrasive material) was used to perform the polishing twice. The same procedure as in Example 1 was carried out except for the points mentioned above. The obtained coated molded article is shown in FIG. 4 (surface photograph, magnification: 40 times).

(Comparative example 1)
The same procedure as in Example 2 was carried out except that wood flour was used instead of fiber waste. The obtained coated molded article is shown in FIG. 5 (surface photograph, magnification: 40 times).

The fabric feel of Examples 1 to 3 and Comparative Example 1 was evaluated based on the appearance and smoothness of the touch, and the results are listed in Table 1.
・Appearance (smoothness)
A: Good B: Intermediate C: Bad/Feel (smoothness)
A: Smooth feel B: Medium C: Rough/fabric feel A: Good B: Medium C: Bad

In Examples 1 to 3, the appearance and feel were above a certain level, giving a fabric feel. Comparative Example 1 did not give a fabric feel.

The coated molded article of the present invention is useful for building materials, furniture, shelves, walls of warehouses, walls inside vehicles, etc.

1 Covered molded body 2 Core material 3 Adhesive layer 4 Covering layer

Claims (9)

A molded article of a resin composition containing fibers and a thermoplastic resin,
The fibers are scoured and/or bleached cotton fiber waste ,
The thermoplastic resin has a melting point of 120 to 200°C,
A molded body, wherein the surface of the molded body is polished to expose the fibers. The molded product according to claim 1, wherein the molded product is a coating layer coated on the surface of a core material. The molded article according to claim 1 or 2, wherein the cotton fiber waste has an average fiber length of 1 to 20 mm. The molded article according to any one of claims 1 to 3, wherein the addition ratio of the cotton fiber waste is 5 to 55% by weight, based on the total of fibers and thermoplastic resin. The molded article according to any one of claims 1 to 4 , wherein the cotton fiber waste is process waste generated in the manufacturing process of cotton products. The molded article according to any one of claims 1 to 5 , wherein the thermoplastic resin is a polyolefin resin. The molded article according to claim 2 , wherein the surface of the coating layer is polished in one direction. The molded article according to claim 2 , wherein an adhesive layer is present between the core material and the covering layer. The molded article according to claim 2 , wherein the core material is made of aluminum.

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