JPH10139927A - Recycled resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition being excellent in impact resistant strength, rigidity and surface appearance, and reduced in coloration, by mixing a recycled thermoplastic resin with a specified fiber in a specified mixing ratio. SOLUTION: This composition comprises 99-50wt.% recycled thermoplastic resin, desirably PP or PS and 1-50wt.% polyacrylonitrile fiber desirably comprising an acrylonitrile homopolymer or a copolymer of at least 90wt.% acrylonitrile and at most 10wt.% vinyl monomer copolymerizable therewith and having a fineness of desirably 0.5-50 denier, especially 1-30 denier, a tensile strength of 2.5g/d or above and an initial modulus of 30g/d or above. The composition may further contain e.g. a necessary amount of an inorganic filler such as a glass fiber or a carbon fiber. There is no limitation on the molding method. The processing temperature is desirably below 230 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fiber reinforced resin composition having improved quality by recycling a thermoplastic resin.

[0002]

2. Description of the Related Art With the recent global environmental problems and the depletion of depleted petroleum resources, industrial waste and general waste of thermoplastic resin products are processed into powder or pellets by a crusher or the like. The ratio of using a resin again as a new material is increasing. However, products using such recycled resins cannot avoid a decrease in strength compared to products using unused resins (hereinafter, also referred to as virgin resins), and the required product quality is low. At present, it is used for applications.

On the other hand, Japanese Patent Application Laid-Open No. 63-81162 describes a technique for dramatically improving mechanical properties by adding a polyacrylonitrile fiber to a thermoplastic resin. However, the addition of the polyacryloniloryl-based fiber has the disadvantage that the surface appearance is reduced and the surface is colored.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a resin composition having improved impact strength and rigidity by adding a polyacrylonitrile fiber to a regenerated thermoplastic resin. It is an object of the present invention to provide a resin composition having excellent surface appearance and less coloring as compared with a product using acrylonitrile fiber.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, by blending a polyacrylonitrile fiber with a recycled thermoplastic resin, they have excellent impact strength, rigidity and surface appearance. The present inventors have found that a resin composition having less coloring is obtained, and have accomplished the present invention. That is,
The present invention is as follows. (1) (A) 99-50% by weight of a recycled thermoplastic resin,
(B) A resin composition comprising 1 to 50% by weight of polyacrylonitrile fiber. (2) The resin composition as described in (1) above, wherein the recycled thermoplastic resin is polypropylene or polystyrene. (3) The fineness of the polyacrylonitrile fiber is 0.5 to 5
3. The resin composition according to the above 1 or 2, wherein the denier is 0 denier and the fiber length is 0.5 to 20 mm. (4) above the glass transition temperature of the recycled thermoplastic resin, 250
4. The method for producing a resin composition according to the above 1, 2, or 3, wherein the resin composition is processed and molded at a temperature lower than 0 ° C.

Hereinafter, the present invention will be described in detail. As the type of the recycled thermoplastic resin used in the present invention, for example,
Polypropylene, low, medium, high density polyethylene, polyvinyl chloride, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, polyamide, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene ether, styrene- Thermoplastic resins such as butadiene copolymers and hydrogenated compositions thereof are mentioned, among which polypropylene, low, medium, high density polyethylene, polyvinyl chloride and polystyrene are particularly preferred, and polypropylene resins are most preferred.

The recycled thermoplastic resin used in the present invention is obtained by molding these resins into various shapes and recycling them after use and then collecting them for reuse, or when molding them into various shapes. Examples of the resin include a resin collected for re-forming a by-product or an off-product. It is preferable to use a single kind of these regenerated resins, but they may be a mixture. These resins are pulverized into pellets and powders and reused. These recycled thermoplastic resins may contain unused thermoplastic resins.

The polyacrylonitrile-based fiber in the present invention may be an acrylonitrile homopolymer or a polyacrylonitrile-based polymer fiber comprising 90% by weight or more of acrylonitrile and 10% by weight or less of a vinyl monomer copolymerizable with acrylonitrile. A fiber produced by a generally known method for producing a polyacrylonitrile-based polymer fiber can be used.

The polyacrylonitrile fiber of the present invention has a fineness of 0.5 to 50 denier, preferably 1 to 30 denier.
Denier, more preferably 3 to 20 denier.
If the fineness is less than 0.5 denier, it is not always easy to produce it industrially, and if it exceeds 50 denier, the reinforcing effect tends to be insufficient. In addition, a tensile strength of 2.5
g / d or more, and the initial elastic modulus is preferably 30 g / d or more.

[0010] The fiber length of the polyacrylonitrile fiber in the present invention is preferably 0.5 to 20 mm, more preferably 1 to 10 mm, more preferably 2 to 6 m.
m. If it is less than 0.5 mm, it is not always easy to produce industrially, and it is preferable that the length is longer in order to obtain a reinforcing effect, but if it exceeds 20 mm, the polyacrylonitrile fiber is kneaded in the thermoplastic resin. When extruded, the polyacrylonitrile fibers may become entangled with each other, resulting in insufficient dispersibility and deterioration in physical properties.

The polyacrylonitrile fiber of the present invention may be mixed with a thermoplastic resin without being treated, or the polyacrylonitrile fiber may be previously immersed in an emulsion of epoxy resin, polyvinyl alcohol, polyurethane, or the like and converged. The resin composition of the present invention can be obtained by mixing as a chopped strand cut to a predetermined length after drying.

[0012] The resin composition of the present invention contains 1 to 50% by weight, preferably 1 to 40% by weight, and more preferably 1 to 30% by weight of polyacrylonitrile fiber. If the addition amount is too small, the reinforcing effect becomes insufficient, and if it is too large, molding becomes difficult. The resin composition of the present invention includes inorganic fillers such as glass fibers and carbon fibers, antistatic agents, various stabilizers, nucleating agents, plasticizers, flame retardants, pigments, colorants, and the like, as long as the features are not impaired. Can be appropriately added and used according to a known method.

The method of mixing the components constituting the present invention may be any method. For example, an extruder, a heating roll, a Banbury mixer, a kneader and the like can be used. The method for molding the resin composition of the present invention may be any method, and examples thereof include injection molding, extrusion molding, compression molding, and blow molding.

The processing temperature of the resin composition of the present invention is preferably equal to or higher than the glass transition temperature of the recycled thermoplastic resin and lower than 250 ° C., and more preferably lower than 230 ° C. When the processing temperature is 250 ° C. or higher, the polyacrylonitrile-based fibers are susceptible to thermal deterioration, which leads to a decrease in strength and coloring, which is not preferable. The resin composition of the present invention thus obtained is used for products such as window frames and picture frames, or frames and structural components having complicated forms for furniture, veneers or veneers in laminated structures, and the like. can do.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples. The flexural strength, flexural modulus, and Izod impact strength of the test pieces obtained in Examples and Comparative Examples were determined using the test methods of ASTM D-790 and D-256, respectively.

The degree of coloring is determined by SM manufactured by Suga Test Instruments Co., Ltd.
The color was measured with a color computer SM-5-CH, and the yellowness YI value was determined and evaluated. A smaller value of YI means less coloring. The evaluation criteria of the surface appearance of the molded article were evaluated as x when the polyacrylonitrile fiber was found to be fluffy, and as ○ when it was not.

[Preparation of Raw Materials] (1) Preparation of Recycled Thermoplastic Resin (Component A) Polypropylene resin (Show Allomer MK112 manufactured by Showa Denko KK) and polystyrene resin (Asahi Kasei Kogyo Co., Ltd.)
Asahi Kasei Polystyrene G8102) was extruded at 200 ° C. using a PCM-45 twin-screw extruder manufactured by Ikegai Iron Works Co., Ltd., and pelletization was repeated 5 times to prepare a recycled polypropylene resin and a recycled polystyrene resin. (2) Preparation of polyacrylonitrile fiber (component B) 3000 denier / 1000 filaments, strength 13
g / d, a polyacrylonitrile-based fiber having a performance of an initial elastic modulus of 60 g / d is immersed and passed through an emulsion of bisphenol A type epoxy resin (AER661 manufactured by Asahi Kasei Kogyo Co., Ltd.) having a concentration of 8% by weight and dried. 4mm
A polyacrylonitrile fiber chopped strand cut to length was prepared.

[0018]

Examples 1 and 2 A recycled polypropylene resin and a recycled polystyrene resin were blended in the proportions shown in Table 1 as recycled thermoplastic resins, respectively.
The mixture was melt-kneaded at 200 ° C. using an M-45 twin-screw extruder and pelletized. From these pellets, an injection molding machine (FUNUC
AUTOSHOT Tseries Series 50
A test piece was prepared in D) and evaluated.

[0019]

Comparative Examples 1 and 2 Except for using an unused polypropylene resin and a polystyrene resin which do not pass through a twin-screw extruder in place of the recycled thermoplastic resin at the ratios shown in Table 1,
After melting and kneading with polyacrylonitrile fiber chopped strand and pelletizing in the same manner as in Examples 1 and 2,
Test pieces were prepared by an injection molding machine and evaluated.

Table 1 shows the evaluation results of the examples and comparative examples.

[0021]

[Table 1]

[0022]

Industrial Applicability The resin composition of the present invention can provide an industrially useful material which is excellent in impact strength, rigidity and surface appearance and is less colored. Further, the recycled resin can be effectively used.

Claims (4)

[Claims] (A) 99 to 50% by weight of a recycled thermoplastic resin, and (B) 1 to 50% by weight of a polyacrylonitrile fiber.
A resin composition comprising: 2. The resin composition according to claim 1, wherein (A) the recycled thermoplastic resin is polypropylene or polystyrene. 3. The resin composition according to claim 1, wherein the fineness of the polyacrylonitrile fiber is 0.5 to 50 denier and the fiber length is 0.5 to 20 mm. 4. The process for producing a resin composition according to claim 1, wherein the process is carried out at a temperature not lower than the glass transition temperature of the regenerated thermoplastic resin and lower than 250 ° C.