SMC轻量化初步探究

为实现SMC轻量化,通过模压工艺,从原材料选型、配方设计以及工艺过程控制三个方面对轻质SMC(片状模塑料)进行了探究。首先,通过研究不同类型中空玻璃微珠(HGS)对制品比重、光亮度以及弯曲强度的影响发现,VS5500和H40适合作为轻量化SMC轻质填料,制品的设计密度和真实密度比较接近,且力学性能损失较小。其次,通过配方设计,研究了中空微珠用量、增稠剂类型以及增稠剂用量对制品比重的影响。同时研究了玻纤含量和树脂类型对制品力学性能的影响。研究结果表明,轻质SMC的设计密度不能过低,否则制品中HGS的破损比例将会增加。研究发现EK100作为增稠剂,树脂糊前期粘度可以有效控制,后期粘度快速上升,可以有效防止中空微珠相分离的发生。此外,随着玻纤含量从25%增加到30%,制品力学性能呈现增加趋势,弯曲强度从148 MPa增加到172 MPa,但随着玻纤进一步提高,弯曲强度反而出现大幅度衰减,降到140 MPa。通过研究三种不同类型树脂对制品外观和力学性能的影响,使用P18-03树脂压制的制品外观最好,其弯曲强度为172 MPa,满足汽车外饰件力学性能要求。最后,通过工艺过程控制,研究了微珠处理工艺对制品比重的影响。结果表明,烘干处理的HGS可以有效降低树脂糊的水含量,从而保证树脂糊后期粘度可以达到适合模压的窗口。

PRELIMINARY STUDY ON LOW DENSITY SMC

Aiming at achieving low density SMC,raw material selection,formulation design,process control of SMC were studied by molding process.Firstly,the density,the radiance and flexural strength properties of SMC product were investigated by using different hollow glass spheres (HGS).It was found that VS5500 and H40 were appropriate packing for low density SMC.Since the design density and real density of the two products are similar,the mechanical property has small losses.Secondly,the glass fiber content and resin type on mechanical property were also investigated.The survey results indicated that the density of SMC product should be larger than 1.2 g/cm3.Otherwise,the breakage rate of hollow glass spheres will be increased.At the same time,EK100 is a good choice because of effective control of the resin paste viscosity.In addition,the product mechanical properties were enhanced from 148 MPa to 172 MPa by increasing glass fiber from 25％ to 30％.If the glass fiber continue to increase,flexural strength would reduce to 140 MPa.The appearance and mechanical properties by using three different types of resin were also studied.It was found that the appearance of product is the best by using P18-03 resin,and flexural strength is 172 MPa,which can satisfy the requirement of automotive mechanical.Lastly,the relationship between parts density and treatment on hollow glass spheres was estimated.The results showed that drying glass spheres can effectively reduce the water content in the resin paste,ensuring SMC compound with an appropriate window for molding.