Recovering and granulating method of high-performance glass fiber reinforced flame-retardant secondary PA46 (Polytetramethylene Adipamide 46) material

Abstract

The invention discloses a recovering and granulating method for a high-performance glass fiber reinforced flame-retardant secondary PA46 (Polytetramethylene Adipamide 46) material. The recovering and granulating method comprises the steps of crushing a secondary material or unqualified part generated in an injection molding process of a glass fiber reinforced flame-retardant PA46 material; sieving and removing metal chips; carrying out extrusion molding by using a single screw extruder, wherein the processing temperature ranges from 295 DEG C to 330 DEG C; carrying out stay conveyance by using a metal chain; when the material is cooled, granulating to obtain a recovered granulated material. According to the method, the shearing action of the single screw extruder is relatively weak, and the secondary material to be recovered is only subjected to weak shearing action in a plasticizing process, so that the length of glass fiber can be kept at a relatively large value, and the damage to a macromolecular chain segment of the PA46 is reduced; compared with a method for extruding and granulating by using a double screw extruder, the method disclosed by the invention has the advantages that the mechanical performance and the heat resistance are both kept at better values: the maximum reduction amplitude of the mechanical performance is not higher than 10%, the reduction amplitude of the thermal deformation temperature is not higher than 2.6 DEG C, and the granulation loss rate is not higher than 1.2%, so that the utilization ratio of the glass fiber reinforced flame-retardant secondary PA46 material can be increased.

Description

technical field [0001] The invention relates to the processing technology of high-temperature-resistant engineering plastics, in particular to a method for recycling and granulating secondary materials of high-performance glass fiber-reinforced flame-retardant polybutylene adipamide (PA46). Background technique [0002] Polybutylene adipamide (PA46) is an aliphatic polyamide formed by the polycondensation of butylenediamine and adipic acid. It was first industrially produced by the Dutch DSM company in 1989. The company's current PA46 output is about 25kt / a. Although it has a molecular structure similar to that of nylon 66, PA46 has more amide groups per given chain length, the lowest content of methylene and amide groups, and a more symmetrical chain structure; the highly symmetrical chain structure leads to its crystallization High temperature (45% ~ 70%), and fast crystallization speed, so the melting point is higher (295°C), the heat distortion temperature is also high, ...

AI Technical Summary

Problems solved by technology

[0004] For the development of the current industrial level, the secondary material recycling method of glass fiber reinforced flame retardant PA46 is mainly the twin-screw extrusion method. Although this method has the advantages of high production efficiency and uniform and dense particles, due to the The secondary material will be subjected to relatively strong shear during the twin-screw extrusion process, resulting in the reduction of glass fiber length and the cutting of PA46 polymer chain segments. The overall mechanical properties of the glass fiber reinforced flame retardant PA46 pellets obtained in this way The drop rate is greater than 25%, and the heat-resistant temperature drop rate is greater than 5°C, which seriously affects the use of glass fiber reinforced flame-retardant PA46 pellets

In addition, due to the large amount of twin-screw extrusion, the secondary material of glass fiber reinforced flame retardant PA46 is prone to uneven flow, melt fracture at the die mouth of the machine head, which cannot be extruded normally, and accumulates into blocky glass Fiber-reinforced flame-retardant PA46 block, unusable, increasing loss rate

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