| 摘要 |
Varnish for separating the colour screen from the emulsion in photographic multicolourscreen material comprises a composition which includes a resin of the kind known under the Registered Trade Mark "Glyptal." A drying oil such as linseed oil or tung oil is included in the varnish. The composition Paralac includes these ingredients and to it may be added inert substances to aid the drying, examples being cellulose esters or ethers, e.g. cellulose dilaurate, dinitrolaurate diacetylpalmitate; or chlorinated rubber compounds such as Pergut, or metallic driers such as lead resinate, linolate or tungate. Drying may also be improved by adding polymerized vinyl ester resins such as Mowilith. A wetting agent is also added, e.g. the substance sold under the Registered Trade Mark "Perminal." Plasticizers of the type such as triarylphosphates, cyclohexanol are also added. The solid is dissolved in benzene, toluene and xylene or substituted hydrocarbons, the solution containing about 12 /ba1/2/be per cent solid. When benzyl cellulose is employed in the mixture a small percentage of alcohol is added and the solution is made more dilute. In general the Paralac is diluted with four times its volume of benzene etc.; the Pergut or other drying product is dissolved in five times its weight of a mixture of benzene and xylene; and the Mowilith is dissolved to form a 25 per cent solution in benzene, the solutions being then mixed together. Specification 401,719 [Group XX], is referred to. |
