# US 10,118,427 B2 · Thermosensitive recording materials containing chelating agents

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- Number: US 10,118,427 B2
- Document ID: US10118427B2
- Status: Granted
- Kind: B2
- Application number: 15/448,840
- Filed: 2017-03-03
- Published: 2017-09-21
- Granted: 2018-11-06
- Earliest claimed: 2016-03-17
- Assignees: Ricoh Company, Ltd.
- Applicants: Laurence Daudin; Florence Gayrard; Daiki Iwata
- Inventors: Laurence Daudin; Florence Gayrard; Daiki Iwata
- Web page: https://patentgrep.com/patent/US10118427B2

## CPC

- B41M 5/506: {Intermediate layers}
- B41M 5/26: Thermography (B41M5/20, B41M5/24 take precedence); {Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used (B23K takes precedence; thermographic or photothermographic systems using noble metal compounds G03C1/494)}
- B41M 5/3375: {Non-macromolecular compounds}
- B41M 5/42: Intermediate, {backcoat}, or covering layers {(B41M5/405 takes precedence; multilayer thermal transfer systems in general B41M5/38214)}
- B41M 5/423: {characterised by non-macromolecular compounds, e.g. waxes}
- B41M 5/323: Organic colour formers, e.g. leuco dyes
- B41M 5/3275: {Fluoran compounds}
- B41M 2205/04: Direct thermal recording [DTR]
- B41M 2205/38: Intermediate layers; Layers between substrate and imaging layer
- B41M 2205/40: Cover layers; Layers separated from substrate by imaging layer; Protective layers; Layers applied before imaging
- B41M: PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING, (correction of typographical errors B41J; processes for applying transfer pictures or the like B44C1/16; fluid media for correction of typographical errors by coating C09D10/00; printing textiles D06P)

## Abstract

The present invention relates to thermal recording materials comprising (in order): a support (base) layer; one or more “undercoat” layers; a thermal layer (thermosensitive coloring layer); and one or more “protective” layers, wherein the thermal recording material contains an aminocarboxylic and/or phosphorus-based chelating agent. The thermal (thermosensitive) recording materials of the invention show enhanced plasticizer resistance and/or preprint uniformity.

## Claims

### Claim 1

A thermal recording material comprising:
a base layer;
one or more undercoat layers which is/are laid down on the base layer;
a thermo-sensitive coloring layer which is laid down on the uppermost undercoat layer, on the opposite side with respect to the base layer; and
one or more protective layers which is/are laid down on the thermo-sensitive coloring layer, on the opposite side with respect to the undercoat layer(s),
wherein one or more of said protective layer(s) and/or said thermosensitive layer contains a chelating agent whose structure is given by following general formula (1):
wherein R1 is a linear alkyl group of 1 to 8 carbon atoms, optionally substituted with one or more carboxyl groups —CO2M, wherein M is hydrogen, ammonium or substituted ammonium, alkali metal, alkaline earth metal or a combination thereof.

### Claim 2 (depends on 1)

The thermal recording material according to claim 1, wherein the chelating agent is:
methylglycine diacetic acid (MGDA) or salts thereof, having R1=—CH3; or
glutamic diacetic acid (GLDA) or salts thereof, having R1=—(CH2)2-CO2M, where M is defined as in claim 1.

### Claim 3 (depends on 1)

The thermal recording material according to claim 1, wherein one or more of the said undercoat layer(s) and/or the thermo-sensitive coloring layer and/or one or more of the said protective layer(s) further contains a phosphorus-based chelating agent.

### Claim 4 (depends on 1)

A thermal recording material according to claim 1, wherein the thermo-sensitive layer contains a leuco dye and a developer.

### Claim 5 (depends on 1)

An image forming method including recording an image on the thermal recording material according to claim 1 using an image recording unit, which is any one of a thermal head and a laser.

### Claim 6

A thermal recording material comprising:
a base layer;
one or more undercoat layers which is/are laid down on the base layer;
a thermo-sensitive coloring layer which is laid down on the uppermost undercoat layer, on the opposite side with respect to the base layer; and
one or more protective layers which is/are laid down on the thermo-sensitive coloring layer, on the opposite side with respect to the undercoat layer(s),
wherein one or more of the said undercoat layers contains an aminocarboxylic acid chelating agent.

### Claim 7 (depends on 6)

The thermal recording material according to claim 6, wherein the aminocarboxylic acid chelating agent contains —N—CH2-CH2-N— groups and/or —N—CH2-CO2M groups, wherein in —CO2M, M is hydrogen, ammonium or substituted ammonium, alkali metal, alkaline earth metal or a combination thereof.

### Claim 8 (depends on 7)

The thermal recording material according to claim 7, wherein the chelating agent whose structure is given by following general formula (1):
wherein R1 is a linear alkyl group of 1 to 8 carbon atoms, optionally substituted with one or more carboxyl groups —CO2M, wherein M is hydrogen, ammonium or substituted ammonium, alkali metal, alkaline earth metal or a combination thereof.

### Claim 9 (depends on 7)

The thermal recording material according to claim 7, wherein the chelating agent is:
methylglycine diacetic acid (MGDA) or salts thereof; or
glutamic diacetic acid (GLDA) or salts thereof.

### Claim 10 (depends on 7)

The thermal recording material according to claim 7, wherein the chelating agent is:
ethylendiamine tetraacetic acid (EDTA) or salts thereof; or
hydroxyethylendiamine triacetic acid (HEDTA) or salts thereof.