| 摘要 |
951,507. Thermographic sheets. NATIONAL CASH REGISTER CO. June 19, 1962 [Sept. 18, 1961], No. 23468/62. Heading G2C. A copy sheet consists of a web having a heat sensitive coating containing a thermochromic 1, 3, 3 trimethyl-spiro [2<SP>1</SP>H-1<SP>1</SP>-benzo pyran)-2, 2<SP>1</SP>- indoline] of formula containing chloro, alkoxy or nitro substituents and at least a leuco methylene blue, of formula where R is benzoyl, iso-valeryl, iso-batyryl or propionyl these compounds being included in a binder containing a buffer to hold the coating at a pH of 7 so that it becomes coloured in heated areas. The coating may also contain a colour intensifier e.g. thiocarbanilide or thiourea or a derivative thereof, and a colour fixer e.g. urea. Specified substituted spiro-pyrano are 5- chloro, 6<SP>1</SP>-nitro; 5-chloro, 6<SP>1</SP>-nitro, 8<SP>1</SP>-ethoxy; 8<SP>1</SP>-methoxy; 6<SP>1</SP>, 8<SP>1</SP> - dinitro; 6<SP>1</SP>- nitro, 8<SP>1</SP>-methoxy; 6<SP>1</SP>-nitro, 8<SP>1</SP>-ethoxy; 8<SP>1</SP>-nitro; 6<SP>1</SP>-vitro; 4, 7, 8<SP>1</SP>-trimethoxy; 5-chloro, 8<SP>1</SP>-methoxy and 5-chloro, 6<SP>1</SP> nitro, 8<SP>1</SP> methoxy. Specification 887,958 is referred to. |
