Heat-sensitive recording medium, and coating liquid for forming heat-sensitive color-developing layer
View Patent ↗A heat-sensitive color-developing layer of a heat-sensitive recording medium and a coating liquid for forming the heat-sensitive color-developing layer each contain a leuco dye, a color developing agent and a polyvinyl alcohol resin containing an acetoacetyl group and a sulfonic acid group or a combination of a polyvinyl alcohol resin containing an acetoacetyl group and a polyvinyl alcohol resin containing a sulfonic acid group. Therefore, the heat-sensitive recording medium and the coating liquid for forming the heat-sensitive color-developing layer are excellent in light resistance, and free from unintended color development and discoloration even when exposed to ultraviolet radiation.
1. A heat-sensitive recording medium comprising:
a support base; and
a heat-sensitive color-developing layer provided on the support base;
wherein the heat-sensitive color-developing layer comprises a leuco dye, a color-developing agent, and a polyvinyl alcohol resin containing an acetoacetyl group and a sulfonic acid group.
2. The heat-sensitive recording medium according to claim 1 , wherein the acetoacetyl group- and sulfonic acid group-containing polyvinyl alcohol resin has an acetoacetyl group content of 0.1 to 20 mol %, and a sulfonic acid group content of 1 to 20 mol %.
3. The heat-sensitive recording medium according to claim 1 , wherein the acetoacetyl group-containing polyvinyl alcohol resin is crosslinked by a glyoxylic acid salt.
4. The heat-sensitive recording medium according to claim 3 , wherein the glyoxylic acid salt is an alkali metal salt or an alkali earth metal salt of glyoxylic acid.
5. A heat-sensitive recording medium comprising:
a support base; and
a heat-sensitive color-developing layer provided on the support base;
wherein the heat-sensitive color-developing layer comprises a leuco dye, a color-developing agent, a polyvinyl alcohol resin containing an acetoacetyl group, a polyvinyl alcohol resin containing a sulfonic acid group, and a glyoxylic acid salt.
6. The heat-sensitive recording medium according to claim 5 , wherein the acetoacetyl group-containing polyvinyl alcohol resin has an acetoacetyl group content of 0.1 to 20 mol %, and the sulfonic acid group-containing polyvinyl alcohol resin has a sulfonic acid group content of 1 to 20 mol %.
7. The heat-sensitive recording medium according to claim 5 , wherein the glyoxylic acid salt is an alkali metal salt or an alkali earth metal salt of glyoxylic acid.
8. A coating liquid for forming a heat-sensitive color-developing layer, the coating liquid comprising:
a leuco dye,
a color-developing agent,
a polyvinyl alcohol resin containing an acetoacetyl group and a sulfonic acid group, and water.
9. The coating liquid for forming the heat-sensitive color-developing layer according to claim 8 , the coating liquid further comprising a glyoxylic acid salt.
10. A coating liquid for forming a heat-sensitive color-developing layer, the coating liquid comprising:
a leuco dye,
a color-developing agent,
a polyvinyl alcohol resin containing an acetoacetyl group,
a polyvinyl alcohol resin containing a sulfonic acid group,
a glyoxylic acid salt, and
water.