Thermo-sensitive multi-color recording material and process for preparation thereof
AssigneeRicoh Company, Ltd.
InventorsKeishi Kubo, Tetsuo Tanaka
Life of this patent
Estimating the term…
Abstract
A multi-color thermo-sensitive recording material comprises two thermo-sensitive coloring layers capable of forming different colors respectively at different temperatures, which are formed one over the other on a support member, and a discoloring layer comprising a cross-linking type resin, which is disposed between the two thermo-sensitive coloring layers, and which is cross-linked in the course of the coating of the thermo-sensitive layers, without being dissolved into any of the two thermo-sensitive coloring layers.
Claims9
In a multi-color thermo-sensitive recording material comprising a support material carrying, in the following order, a lower thermo-sensitive coloring layer, a decoloring layer and an upper thermo-sensitive coloring layer, said lower thermo-sensitive coloring layer being capable of forming a first color at a first temperature, said upper thermo-sensitive coloring layer being capable of forming a second color at a second temperature which is lower than said first temperature, said second color being different from said first color, and said decoloring layer is capable of decoloring said upper thermo-sensitive coloring layer in such a manner that the color of said upper thermo-sensitive coloring layer does not overlap the color of said lower thermo-sensitive coloring layer, the improvement which comprises:
- (i) said upper thermo-sensitive coloring layer comprises a colorless or light-colored leuco dye color former, an acidic color developer and a binder material;
- (ii) said decoloring layer comprises a decoloring agent capable of decoloring said upper thermo-sensitive coloring layer when said upper thermo-sensitive layer is heated to said first temperature, and a cross-linking type resin which is cross-linked in the course of the coating of said layers;
- (iii) said lower thermo-sensitive coloring layer contains a color former and a color developer, which form a color different from the color formed by said upper thermo-sensitive coloring layer.
In a two color, thermo-sensitive, recording material, comprising:
- a support, a lower thermo-sensitive coloring layer coated on said support, an intermediate layer coated on said lower thermo-sensitive coloring layer and an upper thermo-sensitive coloring layer coated on said intermediate layer, said lower thermo-sensitive coloring layer containing a color former and a color developer capable of reacting at a first temperature to form a first color, said upper thermo-sensitive coloring layer containing a colorless or light-colored leuco dye color former and an acidic color developer, said leuco dye color former and said acidic color developer being capable of reacting at a second temperature which is lower than said first temperature, to form a second color which is different from said first color, said intermediate layer containing a material capable of decoloring in said upper thermo-sensitive layer when said upper thermo-sensitive layer is heated to said first temperature, the improvement which comprises:
- said intermediate layer also contains a cross-linked, water-insoluble resin effective to prevent said intermediate layer from being substantially dissolved in said upper thermo-sensitive layer during the coating of said upper thermo-sensitive layer on said intermediate layer whereby to prevent contamination of said upper thermo-sensitive layer by said intermediate layer.
A method for preparing a two color, thermo-sensitive, recording material, comprising a support, a lower thermo-sensitive coloring layer coated on said support, an intermediate layer coated on said lower thermo-sensitive coloring layer and an upper thermo-sensitive coloring layer coated on said intermediate layer, said lower thermo-sensitive coloring layer containing a color former and a color developer capable of reacting at a first temperature to form a first color, said upper thermo-sensitive coloring layer containing a colorless or light-colored leuco dye color former and an acidic color developer, said leuco dye color former and said acidic color developer being capable of reacting at a second temperature which is lower than said first temperature, to form a second color which is different from said first color, said intermediate layer containing a material capable of decoloring in said upper thermo-sensitive layer when said upper thermo-sensitive layer is heated to said first temperature.
- comprising the steps of:
- coating on said support a first layer of a first aqueous liquid composition containing said color former and said color developer and then drying said first layer to form said lower thermo-sensitive coating layer;
- then coating on said lower thermo-sensitive layer a second layer of a second aqueous composition containing said material and a water-soluble cross-linkable resin capable of being cross-linked to form a water-insoluble resin and then drying said second layer to form said intermediate layer and effecting cross-linking of said resin to form a cross-linked water-insoluble resin in said intermediate layer;
- and then coating on said intermediate layer a third layer of a third aqueous composition containing said leuco dye color former and acidic color developer and then drying said third layer to form said upper thermo-sensitive layer, said cross-linked water-insoluble resin being effective to prevent dissolving of said intermediate layer in said third aqueous composition.
Dependencies are inferred from the claim text.