Water-dispersible direct thermal or inkjet printable media
Dispersible record materials or media include a water-soluble or water-dispersible paper substrate, a printable layer carried by the substrate, and a base coat between the substrate and the printable layer. The printable layer may be a thermally responsive layer, e.g. containing a leuco dye and an acidic color developer, or an inkjet receptive layer. The binder material used in the base coat, and the base coat itself, are non-water-soluble, but nevertheless tailored in such a way that the record material as a whole is water-dispersible, i.e., it breaks apart under the influence of water with minimal agitation. The binder material of the base coat is preferably a non-resinous binder, a particulate binder, and/or a binder derived from a dispersion, such as latex. Use of such a binder material in a carefully selected concentration, with other elements, provides a base coat that allows for high quality images to be thermally printed at high print speeds on the thermally responsive layer.
1. A record material, comprising:
a substrate that includes water-soluble paper or water-dispersible paper;
a thermally responsive layer carried by the substrate; and
a base coat between the substrate and the thermally responsive layer;
wherein the base coat includes a non-water-soluble binder and a hollow sphere pigment (HSP), the HSP being present in the base coat in a concentration from 20-50 wt %.
2. The record material of claim 1 , wherein the record material is water dispersible even though the base coat is non-water-soluble.
3. The record material of claim 1 , wherein the non-water-soluble binder is non-resinous, or particulate, or derived from a dispersion.
4. The record material of claim 1 , wherein the non-water-soluble binder includes latex.
5. The record material of claim 1 , wherein the non-water-soluble binder is latex, and wherein the latex is present in the base coat in a concentration from 10-30 wt %.
6. The record material of claim 5 , wherein the latex is present in the base coat in a concentration from 15-20 wt %.
7. The record material of claim 1 , wherein the HSP is present in the base coat in a concentration from 30-50 wt %.
8. The record material of claim 1 , wherein the base coat includes a second pigment selected from the group of clay particles, precipitated calcium carbonate, and fumed silica.
9. The record material of claim 8 , wherein the second pigment is present in the base coat in a concentration less than 80 wt %.
10. The record material of claim 9 , wherein second pigment is present in the base coat in a concentration from 10-50 wt %.
11. The record material of claim 1 , wherein the substrate contains pulp, and wherein purified pulp containing at least 88 wt % of α-cellulose, or containing less than 12 wt % of hemi-cellulose, accounts for less than 15 wt % of all the pulp in the substrate.
12. The record material of claim 1 , wherein the substrate contains pulp, and wherein purified pulp containing at least 88 wt % of α-cellulose, or containing less than 12 wt % of hemi-cellulose, accounts for 15-95 wt % of all the pulp in the substrate.