JP-2026074551-A - Method for manufacturing repellets and repellets

Abstract

[Problem] To provide a new recycling method that can efficiently recycle PBT resin compositions containing fibrous fillers that have been collected from the market, and that can produce recycled molded products with less warping. [Solution] A method for producing repellets, the method comprising kneading a molded article and/or a pulverized article containing a polybutylene terephthalate resin (A) and a fibrous filler (B) to adjust the weight-average fiber length of the fibrous filler (B) in the repellet to 200 μm or less. [Selection Diagram] None

Inventors

• 市川 真衣
• 浅井 吉弘

Assignees

• ポリプラスチックス株式会社

Dates

Publication Date

20260507

Application Date

20241021

Claims (4)

1. A method for producing repellets, The above-mentioned manufacturing method is a method for producing repellets, comprising kneading a molded article and/or a pulverized article containing a polybutylene terephthalate resin (A) and a fibrous filler (B) to adjust the weight-average fiber length of the fibrous filler (B) in the repellet to 200 μm or less.
2. A repellet comprising polybutylene terephthalate resin (A) and a fibrous filler (B) with a weight-average fiber length of 200 μm or less.
3. A molded article of the repelletized material according to claim 2.
4. A molded article of a composite material comprising the repellets described in claim 2 and a molded article and/or a pulverized product thereof containing a polybutylene terephthalate resin composition that does not contain the fibrous filler (B).

Description

This disclosure relates to a method for producing refellises and to refellises. Polybutylene terephthalate resin (hereinafter sometimes referred to as "PBT resin") is used as an engineering plastic in various applications such as automotive parts and electrical/electronic components due to its excellent mechanical properties, electrical properties, heat resistance, chemical resistance, and solvent resistance. In particular, since the mechanical properties and load deflection temperature are improved by adding fibrous fillers such as glass fibers and carbon fibers to PBT resin, polybutylene terephthalate resin compositions containing fibrous fillers (hereinafter sometimes referred to as "fibrous filler-containing PBT resin compositions") are widely used. On the other hand, in recent years, there has been a growing demand for the efficient recycling of resin molded products in order to realize a sustainable society. Engineering plastics, such as PBT resin, have various additives such as inorganic fillers, impact modifiers, and flame retardants added to them according to market demands. In injection molding plants, discarded shots, sprues, and runners are sometimes crushed on-site and reused to produce recycled material with the same composition as virgin material, thereby producing molded products of stable quality. However, the amount of recycled material is small. Therefore, in order to obtain recycled products with stable quality, such as mechanical properties, it is necessary to separate the products collected from the market by resin type and then sort them according to the amount of inorganic filler added for recycling. However, such methods are costly and difficult to implement. Furthermore, recycled material tends to have lower physical properties compared to virgin material. Therefore, currently, the only practical recycling methods for molded products collected after they have been released to the market (market-recovered products) are thermal recycling and chemical recycling. To address these issues, Patent Document 1 describes that, for process waste polyamide containing glass fibers, adding glass fibers to match the glass fiber length distribution of virgin material and then repelling it can maintain physical properties comparable to virgin material. However, this method assumes the use of process waste with a known composition and cannot be applied to molded products of resin compositions with unknown compositions, such as those returned to the market. Furthermore, no conventionally known recycling method exists for efficiently recycling market-recovered PBT resin compositions containing fibrous fillers. Japanese Patent Application Publication No. 9-24516 This is an explanatory diagram illustrating the dimensions of the mold used for warpage measurement in the example. One embodiment of this disclosure will be described in detail below. This disclosure is not limited to the following embodiment and may be implemented with appropriate modifications, provided that the effects of this disclosure are not impaired. Each configuration and combination thereof in each embodiment is an example, and configurations can be added, omitted, replaced, and otherwise modified as appropriate, without departing from the spirit of this disclosure. This disclosure is not limited by the embodiments. Each aspect disclosed herein can be combined with any other features disclosed herein. If a specific description given for one embodiment also applies to other embodiments, that description may be omitted in the other embodiments. In this disclosure, the expression "X to Y" for a numerical range means "X or greater and Y or less". [Method for manufacturing repellets] A first embodiment of this disclosure relates to a method for producing repelletized products. In other words, the first embodiment relates to a method for producing repellets, the method comprising kneading a molded article and/or a pulverized product thereof containing a polybutylene terephthalate resin (A) and a fibrous filler (B) to adjust the weight-average fiber length of the fibrous filler (B) in the repellet to 200 μm or less. According to the production method of the first embodiment, market-recovered PBT resin compositions containing fibrous fillers can be efficiently recycled, and recycled molded articles with less warping than virgin material can be obtained. In this disclosure, "virgin material" means a resin composition comprising PBT resin (A) and a fibrous filler (B), or pellets and/or pulverized products thereof of a resin composition comprising PBT resin (A) but not comprising a fibrous filler (B), which are not on the market (including unused materials). "Recycled molded products" refer to molded products that have been remolded using recycled materials. "Market recalled products" refers to molded products and/or their crushed products that have been recovered after being used in the market. In addition, recovered products such as sprues, r