Preparation method of polyamide flame-retardant material for laser sintering

Abstract

The invention provides a preparation method of a polyamide flame-retardant material for laser sintering, and the method comprises the following steps: adding dried polyamide resin, a flame retardant,an antioxidant, a compatilizer and an inorganic filler into a screw extruder for extrusion granulation to prepare polyamide flame-retardant particles, wherein the polyamide flame-retardant particles comprise, by mass, 34-87.9 wt.% of polyamide resin, 10-30 wt.% of the flame retardant, 0.1-1 wt.% of the antioxidant, 2-5 wt.% of the compatilizer and 0-30 wt.% of the inorganic filler; the polyamide flame-retardant particles are prepared into polyamide flame-retardant power through a cryogenic crushing process, and the polyamide flame-retardant power is dried and screened to obtain the polyamide flame-retardant powder with the particle size ranging from 30 to 100 microns; the polyamide flame-retardant powder and a power flow aid are evenly mixed to prepare the polyamide flame-retardant powdermaterial for selective laser sintering, wherein the polyamide flame-retardant powder material comprises, by mass, 99 wt.% to 99.8 wt.% of the polyamide flame-retardant powder and balance of the powerflow aid, and the powder flow aid is a hydrophobic flow aid with an organically-treated surface. The flame retardant is tightly combined with polyamide, is not easy to separate from each other, and has good flame retardant performance.

Description

technical field [0001] The invention belongs to the technical field of additive manufacturing, and in particular relates to a method for preparing a polyamide flame-retardant material used for laser sintering. Background technique [0002] Laser sintering is a method of manufacturing three-dimensional objects by selectively fusing multiple layers of powder, which allows machining without the use of tools but simply by laser sintering multiple overlapping layers of powder according to a three-dimensional image of the object to be produced. 3D solid. This method is mainly accomplished using thermoplastic polymers, and patents US6136948 and WO9606881 describe in detail the method of using powdered polymers to manufacture three-dimensional objects. [0003] Polyamide is a class of thermoplastic engineering plastics with excellent performance. It has good mechanical and mechanical properties and chemical corrosion resistance, and is widely used in industrial fields. Compared wi...

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Problems solved by technology

However, polyamide materials do not have flame retardant properties. During the combustion process, a large amount of dense smoke and molten droplets will be generated, which can easily spread flames, which greatly limits its application in special fields such as aerospace, automobile manufacturing, and electronic appliances.

[0004] Patent CN106987116A discloses a method for preparing a polyamide flame retardant material. The flame retardant polyamide material is prepared by mixing polyamide powder with a flame retardant. This method has a simple process, but there are also many disadvantages: 1. Polyamide It is difficult to mix the powder and the flame retardant evenly; 2. Adding a large amount of flame retardant to the polyamide powder reduces the fluidity of the powder and affects the sintering process; 3. The laser energy directly acts on the flame retardant during the sintering process, resulting in the decomposition of the flame retardant , affect the flame retardant effect; 4. Some components in the flame retardant are easily decomposed by heat energy and laser, and the resulting low molecular substances condense in the cavity and window mirror of the sintering equipment, affecting the function and life of the equipment, and hindering the laser energy Penetration, greatly reducing the mechanical properties of the part and the effective printing height

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