JP7450877B2 - Fiber reinforced molded body - Google Patents

Description

The present invention relates to a fiber-reinforced molded article reinforced with natural fiber waste.

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.

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

However, the above-mentioned conventional technology has the problem that the fibers are deteriorated by heat during the mixing step and/or the molding step, resulting in deterioration of the physical properties of the molded article and deterioration of the appearance quality, and further improvements have been sought.

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

The fiber-reinforced molded article of the present invention is a fiber-reinforced molded article containing reinforcing fibers and a thermoplastic resin, the reinforcing fibers being scouring and/or bleached cotton fiber waste, and the thermoplastic resin having a melting point. The temperature is 120 to 200° C., and the surface of the fiber-reinforced molded article is characterized by the presence of areas with a low fiber concentration and areas with a high fiber concentration, and a fiber pattern.

The fiber-reinforced molded article of the present invention includes reinforcing fibers and a thermoplastic resin, the reinforcing fibers are fiber waste of natural fibers, and the thermoplastic resin has a melting point of 120 to 200°C, thereby preventing deterioration of the fibers. The physical properties of the molded product can be maintained at high levels, and a fiber-reinforced molded product with a high appearance quality can be provided. Further, it is possible to provide a fiber-reinforced molded article that has a fiber pattern and has a good appearance. Furthermore, fiber waste can be used effectively.

FIG. 1 is a schematic perspective view of a fiber-reinforced molded article according to an embodiment of the present invention. FIG. 2 is an enlarged photograph of the surface of the same fiber-reinforced molded product.

The fiber-reinforced molded article of the present invention includes reinforcing fibers and a thermoplastic resin, the reinforcing fibers are fiber waste of natural fibers, and the thermoplastic resin has a melting point of 120 to 200°C. In the present invention, fiber scraps of natural fibers are selected as reinforcing fibers, and a thermoplastic resin with a specific melting point is selected and combined as the matrix resin. Deterioration can be suppressed, the physical properties of the molded product can be maintained at high levels, and a fiber-reinforced molded product with high appearance quality can be obtained. The molded product is a fiber-reinforced molded product with a fiber pattern and a good appearance. When the melting point of the thermoplastic resin is 120 to 200°C, the molded product can withstand hot water and the like, and can be applied to food containers, tableware, etc.

The fiber waste of the natural fiber preferably has an average fiber length of 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.

The addition ratio of the fiber waste of the natural fiber is preferably 5 to 55% by weight, more preferably 10 to 50% by weight, and even more preferably 20 to 55% by weight, when the total of reinforcing fibers and thermoplastic resin is the parameter It is 40% by weight. If it is within the above range, the reinforcing effect of the molded product will be higher, and a fiber pattern will easily appear on the surface of the molded product. If the amount of fiber is small, the pattern will be thin and uniform, but if the amount of fiber is large, there will be areas where the fibers are dispersed and areas where they are concentrated, resulting in a shading pattern. This shading pattern gives it a marble look. If the amount of fiber added is too large, kneading may not be uniform. On the other hand, if it is too small, the reinforcing effect of the molded product will be weakened.

The surface gloss rate of the fiber-reinforced molded article is preferably 5 to 30%, more preferably 6 to 27%. When the surface glossiness is within the above range, the surface of the molded article will not have a glittery appearance and will have a calm appearance.

The natural fibers are preferably vegetable fibers such as cotton, hemp, and rayon, and animal fibers such as silk, wool, alpaca, angora, cashmere, and mohair, and more preferably cotton. Cotton has a high affinity with thermoplastic resins, has a high heat resistance, and is highly effective in reinforcing molded objects. The natural fibers are preferably process 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, you can also use recycled wool scraps such as old clothes. 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 coloring agent is preferably a direct dye, vat dye, sulfur dye, naphthol dye, reactive dye, acid dye, acid mordant dye, or metal complex dye. By adding the colorant, the quality of the external surface of the molded article is increased. It may also be composited with metal, rubber, wood powder, etc.

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.

The fiber waste of the natural fiber and the thermoplastic resin are first mixed together using a kneader such as a kneader at a temperature higher than the melting temperature of the resin to form a compound (mixture), and this compound is extruded and granulated or pulverized. It is preferable to form the pellets into pellets by injection molding, extrusion molding, blow molding, vacuum molding, compression molding, or a combination thereof. In this way, the natural fiber waste and the thermoplastic resin can be uniformly mixed. In the compounding step and/or molding step, additives such as colorants, various stabilizers, dispersants, and compatibilizers may be added. The pellets can also be used as a masterbatch, and new resin can be added during molding. The kneading temperature and molding temperature are set higher than the melting point of the thermoplastic resin.

Since the fiber-reinforced molded article of the present invention contains short natural fibers in the matrix resin, it has a low molding shrinkage rate and high tensile strength, flexural modulus, and flexural strength. In addition, the gloss is favorable, and the appearance shows a fiber pattern.

This will be explained below using the drawings. FIG. 1 is a schematic perspective view of a fiber-reinforced molded article 1 according to an embodiment of the present invention. This fiber-reinforced molded article 1 is a food container, has a fiber pattern on its surface, and has a portion 2 with a low fiber concentration and a portion 3 with a high fiber concentration. This textile pattern has a marble-like beauty.

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

(Example 1)
<Materials>
(1) Reinforcing fiber Cotton fiber waste (raised fiber waste) that had undergone a scouring and bleaching process was used. The average fiber length was 2 mm.
(2) Resin Polypropylene resin (PP) with a melting point of 160°C was used. For example, polypropylene resins such as "Novatec PP" manufactured by Nippon Polypro Co., Ltd. and "Prime Polypro" manufactured by Prime Polymer Co., Ltd. can be used. This resin had a melt flow rate (MFR) of 45 g/10 min at 190° C. and 2.16 kgf.
<Compound>
60 parts by weight of PP and 40 parts by weight of fiber waste were weighed, melted and kneaded in a kneader heated to 190°C, extruded, cooled, crushed, and pelletized. When the total of fiber waste and thermoplastic resin was taken as a parameter, the fiber waste was 40% by weight.
<Molding>
The pellets were injection molded at a temperature of 190° C. to form the food container shown in FIG. The surface of this molded product 1 had a fiber pattern, and there were a portion 2 with a low fiber concentration and a portion 3 with a high fiber concentration, giving it a beautiful marble-like appearance. FIG. 2 is an enlarged photograph of the surface of the fiber-reinforced molded article. This is the name of "T6 compound" in FIG. The physical properties are summarized in Table 1.

(Example 2)
The same procedure as in Example 1 was carried out except that 25 parts by weight of the PP pellets of Example 1 were mixed with 75 parts by weight of the pellets of the compound of Example 1 and injection molding was carried out. The proportion of fiber waste was 30% by weight.

(Example 3)
Example 1 was carried out in the same manner as in Example 1, except that 50 parts by weight of the PP pellets of Example 1 were mixed with 50 parts by weight of pellets of the compound of Example 1, and injection molding was carried out. The proportion of fiber waste was 20% by weight.

(Comparative example 1)
The same procedure as in Example 1 was carried out except that no fiber waste was included and PP pellets were injection molded.
The above results are summarized in Table 1.

As is clear from Table 1, Examples 1 to 3 had low mold shrinkage, high tensile strength, flexural modulus, and flexural strength, favorable gloss, and a fiber pattern was observed in appearance.

(Example 4)
It was carried out in the same manner as in Example 1, except that polypropylene resin (PP) with an MFR of 2.5 g/10 min at 190° C. and 2.16 kgf was used, and the PP was 70 parts by weight and the fiber waste was 30 parts by weight.

(Example 5)
The same procedure as in Example 4 was carried out, except that 33 parts by weight of the PP pellets of Example 4 were mixed with 67 parts by weight of the pellets of the compound of Example 4, and the mixture was injection molded. The proportion of fiber waste was 20% by weight.

(Example 6)
The same procedure as in Example 4 was carried out except that 67 parts by weight of the PP pellets of Example 4 were mixed with 33 parts by weight of the pellets of the compound of Example 4 and injection molding was performed. The proportion of fiber waste was 10% by weight.

As is clear from Table 2, Examples 4 to 6 had low mold shrinkage, high tensile strength, flexural modulus, and flexural strength, favorable gloss, and a fibrous pattern was observed in appearance.

The fiber-reinforced molded article of the present invention is useful for food containers, tableware, storage containers for clothes, etc., housing construction materials, furniture, shelf boards, warehouse walls, walls in vehicles, and the like. It can also be applied to stationery, such as rulers, exterior bodies for housing pens, book stands, and the like.

1 Fiber-reinforced molded body 2 Area with low fiber concentration 3 Area with high fiber concentration

Claims (7)

A fiber-reinforced molded article containing reinforcing fibers and a thermoplastic resin,
The reinforcing fibers are scouring and/or bleached cotton fiber waste,
The thermoplastic resin has a melting point of 120 to 200°C,
The fiber-reinforced molded product is characterized in that the surface of the fiber-reinforced molded product has a portion with a low fiber concentration and a portion with a high fiber concentration, and has a fiber pattern. The fiber-reinforced molded article according to claim 1, wherein the cotton fiber waste has an average fiber length of 1 to 20 mm. The fiber-reinforced molded article according to claim 1 or 2, wherein the addition ratio of the cotton fiber waste is 5 to 55% by weight, based on the total of the cotton fiber waste and the thermoplastic resin. The fiber-reinforced molded article according to any one of claims 1 to 3, wherein the fiber-reinforced molded article has a surface gloss ratio of 5 to 30%. The fiber-reinforced molded article according to any one of claims 1 to 4, wherein a coloring agent is further added to the fiber-reinforced molded article. The fiber-reinforced molded article according to any one of claims 1 to 5, wherein the cotton fiber waste is process waste generated in a manufacturing process or a recycling process of cotton products. The fiber-reinforced molded article according to claim 1, wherein the thermoplastic resin is a polyolefin resin.