High-fluidity polyamide magnetic composite material and preparation method thereof

Abstract

The invention discloses a high-fluidity polyamide magnetic composite material, prepared from the following ingredients in percentage by weight: 4.3-12.2wt% of polyamide resin, 85-93wt% of strontium ferrite, 0.5-1wt% of an internal lubricant, 1-3wt% of a flow modifier, 0-0.2wt% of an external lubricant, 0-0.1wt% of a primary antioxygen, 0-0.1wt% of an auxiliary antioxygen and 0.3-0.8wt% of a coupling agent. A a sa a preparation method comprises the following steps: (1) mixing the strontium ferrite with the coupling agent, then adding the polyamide resin, the internal lubricant, the flow modifier, the external lubricant, the primary antioxygen and the auxiliary antioxygen, and mixing to obtain a mixture; (2) adding the mixture through a main feeding hole of a double-screw extruder, mixing uniformly, then extruding, and granulating by virtue of a granulator, thereby obtaining the high-fluidity polyamide magnetic composite material.

Description

technical field [0001] The invention belongs to the technical field of polymer materials, and in particular relates to a high fluidity polyamide magnetic composite material and a preparation method thereof. Background technique [0002] Magnetic materials usually refer to a class of materials with available magnetic properties. The largest and most widely used magnetic materials are hard magnetic materials and soft magnetic materials. The difference lies in the level of coercive force. Hard magnetic materials, also known as permanent magnetic materials, are mainly divided into casting molding, sintering molding and bonding molding according to manufacturing technology. Among them, the bonded permanent magnet is better than the non-magnetic phase (binder) part, but its magnetic performance is lower than that of the corresponding sintered or cast permanent magnet. However, the bonded permanent magnet market is the fastest growing permanent magnet market in recent years. . Bo...

AI Technical Summary

Problems solved by technology

[0003] The bonded magnet is a thermoplastic resin binder-polymer uniformly coated magnetic powder composite material, in which the magnetic powder is added in an amount of 80%-94% (mass percentage), and the melt of the composite material is a solid phase with a very high solid filling amount Suspension system, compared with pure polymer or filled polymer system, the melt flow performance of bonded magnets is very poor, which greatly weakens the processing performance and magnetic properties of injection-molded magnets. "Technical bottleneck" in magnets

[0004] The prior art for improving the fluidity of polyamide resin-ferrite composites is as follows: Patent US5028347A discloses the use of N-butylbenzenesulfonamide (N-BBSA) as the internal lubrication of nylon (PA) 6 / strontium ferrite system Additives can improve the fluidity of magnetic composite materials, but the initial decomposition temperature of N-BBSA is about 170°C, which is far lower than the processing temperature of the magnetic composite material at 230-280°C. At this temperature, N-BBSA has decomposed and deteriorated. The mechanical and magnetic performance of magnet; Patent US4600752 has reported to use low-viscosity amino resin (Bayer's production brand is Desmophen@3600) to improve the fluidity of PA6, and the result shows that PA6 viscosity hardly declines; "Oleic acid is to ferrite powder / The Influence of Nylon 6 Composite Fluidity" (published in "Plastic Industry" 2010, No. 7, 24-27 pages) reported that nylon (PA) 6 / ferrite powder / oleic acid composite has excellent fluidity, but In this technology, the component oleic acid that improves the fluidity of the material has poor thermal stability, which will lead to material degradation, resulting in a significant drop in mechanical properties, and poor secondary processability of the material; patent US20140303293A1 reports the use of PE wax, EBS or stearic acid Calcium improves the fluidity of polyamide filled with minerals (mass percentage not exceeding 70%). This technology improves the fluidity very little in more than 80% filled PA materials, which cannot meet the processing needs of magnetic plastics.