酸酐改性PVA树脂用于阴图PS版成膜树脂的性能研究

聚乙烯醇(PVA)首先与丁醛进行缩醛反应,再与酸酐进行酯化反应合成了酸酐改性PVA树脂.将此树脂与进口重氮树脂、染料和有机溶剂以一定比例混合形成了阴图PS版感光胶.本文研究了B/P以及酸酐改性PVA树脂的分子量、缩醛度、酯化度等因素对阴图PS版成像性能的影响.结果表明酸酐改性PVA树脂对阴图PS版的显影性能,亲油墨性和耐磨性都起关键作用,对阴图PS版的感度和保存稳定性也有一定影响.因此其分子量、酯化度和缩醛度的确定,必须综合考虑各项性能之间的平衡.缩醛度为60-80 mol%,酯化度10-15mol%,羟基5-25 mol%,分子量约为4-8万,B/P为4-4.5时,制得的阴图PS版的感度、显影性、着墨性和耐磨性都较好.

Characteristic of PVA Resins Esterified with Anhydride as Binders Used in the Negative PS Plate

Modified polyvinyl alcohols(PVA) were synthesized by condensation reaction of PVA with butyraldehyde and then by the esterification reaction with acid anhydride.They were applied to photosensitive composition of negative presensitized plate(PS plate) composed with binder,diazo resin,background dyes and organic solvents.The composition and the imaging performance were studied.The result indicated that modified PVA resin had decisive effect on developability,ink receptivity and scratch resistance and also had strong influence on shelf life and photosensitivity.In addition,when the modified PVA resins fulfilled requirements in the following: 1) the acetalization degree varied from 60 mol% to 80 mol%,2) the esterification degree varied from 10 mol% to 20 mol%,3) the amount of hydroxyl group was 5—25 mol%,4) the range of value of B/P(the mass ratio of the binder to diazo resin) was from 4 to 4.5,5) the range of its molecular weight was from 4×105 to 8×105,the negative PS plate obtained had excellent sensitivity,hydrophobic property,good developability,good ink receptivity and good scratch resistance.