Thermally-responsive record material
View Patent ↗The invention describes an improved thermally-responsive record material substantially free of aromatic isocyanate yielding an image of high intensity and useful for bar codes. The record material comprises a support having provided thereon a heat-sensitive composition comprising a substantially colorless color former comprising a fluoran; and a developer material selected from the group consisting of 4,4′-diaminodiphenylsulfone and 3,3′-diaminodiphenylsulfone, and an organic acid which upon being heated reacts with said color former to develop color, and including a binder material. Optionally, a modifier compound is included in the heat-sensitive composition. The compound can be selected from the group consisting of a fatty acid amide, such as stearmide. Optionally, magnesium state is included.
1. A thermally-responsive record material, substantially free of aromatic isocyanate, the record material comprising a support having provided thereon a heat-sensitive composition comprising:
a substantially colorless color former;
a developer material selected from the group consisting of 4,4′-diaminodiphenylsulfone and 3,3′-diaminodiphenylsulfone, which upon being heated react with said dye precursor to develop color;
an organic acid;
and a binder material.
2. The thermally-responsive record material according to claim 1 wherein the organic acid is a compound according to the formula
wherein each R 1 is independently selected from carboxy, hydrogen or hydroxyl, wherein n is an integer from 1 to 4;
wherein R 2 is selected from carboxy, alkenecarboxy, alkcarboxy, alkanoate, and alkyl alkanoate.
3. The thermally-responsive record material according to claim 2 wherein the organic acid is o-acetyl salicyclic acid, coumaric acid, vanillic acid, cinnamic acid, salicylic acid, 3-(4-hydroxyphenyl)propionic acid, 2-(2-hydroxyphenyl)propionic acid, or 3,4-dihydroxyphenyl acetic acid.
4. The thermally-responsive record material according to claim 1 wherein the organic acid is selected from the group consisting of alkanedienoic acid, alkanedioic acid, hydroxyalkanetricarboxylic acid, and dihydroxyfuranone.
5. The thermally-responsive record material according to claim 4 wherein the organic acid is citric acid, ascorbic acid, sorbic acid, lactic acid or succinic acid.
6. The thermally-responsive record material according to claim 1 wherein the heat-sensitive composition comprises in addition a modifier compound.
7. The thermally responsive record material according to claim 6 wherein the modifier compound is stearamide wax.
8. The thermally responsive record material according to claim 6 wherein the modifier compound is selected from the group consisting of 1,2-diphenoxy ethane, dimethyl diphenoxy ethane, dimethyl phthalate and a fatty amide.
9. The thermally-responsive record material according to claim 1 wherein the heat sensitive composition includes in addition a metal stearate.
10. The thermally responsive record material according to claim 9 wherein the metal stearate is magnesium stearate.
11. The thermally-responsive record material according to claim 1 , wherein the substantially colorless color former comprises a fluoran compound of the formula
wherein R 1 is hydrogen or alkyl
wherein R 2 is hydrogen or alkaryl;
wherein R 3 is aryl when R 2 is hydrogen, or alkaryl when R 2 is alkaryl;
R 4 and R 5 are each independently selected from alkyl, aralkyl; or R 4 and R 5 form a four carbon ring pyrrolidine structure.
12. The thermally-responsive record material according to claim 11 wherein the fluoran is selected from the group consisting of:
13. The thermally-responsive record material according to claim 11 wherein the fluoran is selected from the group consisting of:
14. The thermally-responsive record material according to claim 1 wherein the heat sensitive composition is applied onto the support at from 2 to 8 gsm.
15. The thermally-responsive record material according to claim 1 having an ANSI grade of B or better.
16. The thermally-responsive record material according to claim 1 wherein the record material includes in addition a polymeric top coat.
17. The thermally response record material according to claim 1 wherein the ratio by weight of developer to color former is from 0.5:1 to 5:1.
18. The thermally responsive record material according to claim 1 wherein the modifier to color former ratio by weight is form 0.1:1 to 4:1.
19. An improved bar code comprising a thermally responsive record material according to claim 1 .
20. The improved bar code according to claim 19 having an ANSI grading of C or better.
21. The improved bar code according to claim 19 wherein the developer is selected from 4,4′-diaminodiphenylsulfone and 3,3′-diaminodiphenylsulfone, and the flouran dye is selected from group consisting of:
3-diethylamino-6-methyl1-7-(2′,4′dimethyl aniline)fluoran,
3-dibutylamino-6-methyl-7-anilino fluoran,
3-diethylamino-6-methyl-7-(3′-methylanilino)fluoran,
3-diethylamino-6-methyl-7-anilinofluoran,
3-pyrrolidino-6-methyl-7-anilino fluoran, and
3-diethylamino-7-(dibenzylamino)fluoran, and, including in addition magnesium stearate.