| 摘要 |
1301038 Thermographic materials MINNESOTA MINING & MFG CO 15 June 1970 [16 June 1969] 28944/70 Heading G2C A thermographic material contains a first layer which contains a binder of a vinyl chloride polymer or copolymer and a colour former which reacts with an organic acid on heating to produce a dye and a second layer which contains 40-94% by weight of nitrocellulose, 5-50% by weight of a plasticizer for nitrocellulose and 1-25% by weight of the organic acid reactive with the colour former. The two layers may be self-supporting or coated on a support e.g. a polyester support. Specified colour formers are N-{bis-(4-dimethylaminophenyl)methyl}pyrrolidone and N-(bis-p-dialkylaminoaryl)methanes. Specified organic acids are salicylic, 5-chloro- or 5-bromo-salicylic, gallic, citric, benzoic, p-aminobenzoic and 2, 4- chloromaleic. Specified plasticizers are polyvinylbutyral, camphor and polyalkylene glycols.
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