壳法用酚醛树脂粘连现象的研究

Development About Sticking Together of Novolac Resin for Shell Process

传统方法合成的壳法用热塑性酚醛树脂在高温高湿环境中存放,会出现粘连现象,其使用性能会受到不利影响。为此,利用红外光谱(IR)分析了壳法用热塑性酚醛树脂出现粘连现象的原因,证实在高温高湿的环境中,树脂中的活性点吸引空气中的水分到树脂体系中,使得树脂分子链之间的作用力减小,相互之间可以滑移,在宏观上表现为粘连。为降低热塑性酚醛树脂的粘连倾向,尝试进行了用磷酸为树脂合成组分的试验,结果表明,磷酸不仅可以作催化剂以调整体系的pH值,同时还可以和树脂中的酚羟基发生反应,减少树脂中能够吸引水分的活性点,在磷酸用量适当的条件下,可获得分子量分布窄、抗粘连性能较好、强度足够的热塑性酚醛树脂,并且该树脂的粘连温度与其软化点无明显关系。

Novolac resin synthesized by conventional process will stick together in the hightemperature and high-humidity environment, result in adversely affect on performance of resin. So the phenomenon of sticking together of novolac resin for shell process is analyzed by Infra-red absorption spectrum in this paper, it indicates that in the high-temperature and high-humidity environment, reactive point of resins attracts water into the resin systems. The water reduce effort between molecular chains and it results in slipping among molecular chains, which is the sticking together of resin. To reduce the tendency of sticking together of resin, we use phosphoric acid as a catalyst for synthesizing resin. The results indicate that phosphoric acid may not only be a catalyst to adjust the pH value of system, while it can also esterify phenol hydroxyl in resin, which reduce reactive points attracting moisture in the resins. In phosphoric acid consumption appropriate conditions, we can obtain narrow molecular weight distribution, anti-sticking together better and tensile strength enough novolac resin. And there is no evidence connection between sticking temperature and sorting point of this resin.