照相明胶物性的改进

<正> 照相明胶在卤化银感光材料中起着很重要的作用,至今己有一个多世纪的历史了。但是明胶物性上的某些缺陷,例如吸水性强,吸湿膨胀系数大弹性模数高,明胶膜的机械性能强烈地依赖于环境

Photographic Gelatin with Improved Physical Properties

As an important raw material used in photographic industry gelatin has some disadvantages mainly caused by its large coefficient of expan- sion in respect to humidity and higher modulus of elasticity.Therefore film coated with gelatin layers such as photographic material tonds to curl and has less dimensional stabihty when humidity changes.The hardening of gelatin layers very often results in its increased brittleness and decreases its permeability for the developing and other agents of processing solutions.It also had been found that during high temperature processing the scratch and abrasion resistance of gelatin layer further decreased and with the greater temperature changes reticu- lation tends to form. An important method to improve the above characteristics of gelatin is the addition of polymers to the aqueous solution of gelatin,These polymers can be divided into two groups: 1.Polymers leading to greater dimensional stability,less tendency to curl and decroased britt(?)eness of gelatin layer; 2.Polymers leading to reduced reticulation tendency,increased seratch and abrasion rosistance,higher processing solution penetrating rate and drying speed of gelatin layer. The essential factors in the choice of polymers as partial substitutes for gela- tin are their -Chemical structure -Average molecular weight -Glass transition temperature -Refractive index -Particle size