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US-12623478-B2 - Thermosensitive recording layer forming liquid, thermosensitive recording medium and production method thereof, and image recording method

US12623478B2US 12623478 B2US12623478 B2US 12623478B2US-12623478-B2

Abstract

Provided is a thermosensitive recording medium including a support and a thermosensitive recording layer disposed on or above the support. The thermosensitive recording layer include a compound represented by General Formula (1) and a styrene-acryl resin, where, in General Formula (1), R 2 is a C1-12 straight-chain, branched-chain, or alicyclic alkyl group, C7-12 aralkyl group that is substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group or a halogen atom, or a C6-12 aryl group that is unsubstituted or substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom, where two or more R 2 may be identical to or different from each other; and A 1 is a hydrogen atom or a C1-4 alkyl group, where two or more A 1 , may be identical to or different from each other.

Inventors

  • Shohta KOIDE
  • Kazumasa Noda
  • Takahiro Shibata

Assignees

  • Shohta KOIDE
  • Kazumasa Noda
  • Takahiro Shibata

Dates

Publication Date
20260512
Application Date
20220301
Priority Date
20210322

Claims (19)

  1. 1 . A thermosensitive recording medium, comprising: a support; and a thermosensitive recording layer disposed on or above the support, wherein the thermosensitive recording layer includes a compound represented by General Formula (2) a styrene-acryl resin, and a leuco dye, where, in General Formula (2), R 2 is a C6-12 aryl group that is unsubstituted or substituted with a C1-12 alkyl group, a C1-12 alkoxy group, or a C6-12 aryl group, where the R 2 's may be identical to or different from each other.
  2. 2 . The thermosensitive recording medium according to claim 1 , wherein the compound represented by General Formula (2) is a compound represented by General Formula (3), where, in General Formula (3), R is an alkyl group; and n is an integer of from 0 through 3.
  3. 3 . The thermosensitive recording medium according to claim 1 , wherein the thermosensitive recording layer further includes a photothermal conversion material.
  4. 4 . The thermosensitive recording medium according to claim 1 , wherein the support is a plastic film.
  5. 5 . The thermosensitive recording medium according to claim 1 , wherein the support is a transparent film.
  6. 6 . The thermosensitive recording medium according to claim 1 , further comprising: a printed layer disposed between the support and the thermosensitive recording layer, or on an opposite surface of the support to a surface of the support on which the thermosensitive recording layer is disposed, or on or above the support and the thermosensitive recording layer.
  7. 7 . The thermosensitive recording medium according to claim 1 , wherein an amount of the styrene-acryl resin is 1.0% by mass or greater but 50% by mass or less, relative to a total amount of the thermosensitive recording layer.
  8. 8 . The thermosensitive recording medium according to claim 1 , wherein a deposition amount of a thermosensitive recording layer forming liquid for forming the thermosensitive recording layer is 1 g/m 2 or greater but 20 g/m 2 or less.
  9. 9 . The thermosensitive recording medium according to claim 1 , wherein an image survival rate of the thermosensitive recording layer calculated by results of an image density of the thermosensitive recording layer before and after immersing in water at 23° C., for 96 hours, is 80% or greater.
  10. 10 . The thermosensitive recording medium according to claim 1 , wherein an image survival rate of the thermosensitive recording layer calculated by results of an image density of the thermosensitive recording layer before and after immersing in an 80% by mass ethanol aqueous solution for 30 seconds, is 80% or greater.
  11. 11 . The thermosensitive recording medium according to claim 1 , wherein the compound of General Formula (2) is:
  12. 12 . The thermosensitive recording medium according to claim 1 , wherein an amount of the styrene-acryl resin is 10.0% by mass or greater but 50.0% by mass or less, relative to a total amount of the thermosensitive recording layer.
  13. 13 . The thermosensitive recording medium according to claim 1 , wherein an amount of the styrene-acryl resin is 20.0% by mass or greater but 40.0% by mass or less, relative to a total amount of the thermosensitive recording layer.
  14. 14 . The thermosensitive recording medium according to claim 1 , wherein the compound of General Formula (2) is selected from one of the following compounds:
  15. 15 . A thermosensitive recording layer forming liquid, comprising: a compound represented by General Formula (2) a styrene-acryl resin, a leuco dye, and a solvent, where, in General Formula (2), R 2 is a C6-12 aryl group that is unsubstituted or substituted with a C1-12 alkyl group, a C1-12 alkoxy group, or a C6-12 aryl group, where the R 2 's may be identical to or different from each other.
  16. 16 . The thermosensitive recording layer forming liquid according to claim 15 , wherein the compound represented by General Formula (2) is a compound represented by General Formula (3), where, in General Formula (3), R is an alkyl group; and n is an integer of from 0 through 3.
  17. 17 . A method for producing a thermosensitive recording medium, the method comprising: applying the thermosensitive recording layer forming liquid according to claim 9 onto a support to form a thermosensitive recording layer.
  18. 18 . An image recording method, comprising: irradiating the thermosensitive recording medium according to claim 1 with laser light to record an image.
  19. 19 . An image recording method, comprising: heating the thermosensitive recording medium according to claim 1 with a thermal head to record an image.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the National Stage entry under § 371 of International Application No. PCT/JP2022/008689, filed on Mar. 1, 2022, and which claims the benefit of priority to Japanese Patent Application No. 2021-047167, filed on Mar. 22, 2021. The content of each of these applications is hereby incorporated by reference in its entirety. TECHNICAL FIELD The present disclosure relates to a thermosensitive recording layer forming liquid, a thermosensitive recording medium and production method thereof, and an image recording method. BACKGROUND ART Compared to other recording methods, a thermosensitive recording method using a thermosensitive recording medium has advantages that recording can be performed within a short period of time using a relatively simple device without performing processes, such as developing and fixing, and cost thereof is low. Therefore, use of the thermosensitive recording method has been rapidly spread in the field of food products, such as packed meals, and ready-made meals, where reliability of images is important. In the field of food products, thermosensitive recording media has been used as a label for a PET bottle or a label for fresh food. Therefore, it is expected that a thermosensitive recording medium is exposed in water or hot water during use. When an image area of a thermosensitive recording medium comes in contact with water or hot water, the image area in contact with water or hot water may be discolored or faded. Particularly, discoloring or fading may be expected at a temperature of hot drink sold by bending machines (for example, the temperature is kept at 60° C. for a several hours), a temperature of hot water comes out from a tap (for example, the temperature is kept at 60° C. for a several minutes), or a temperature of a hot wash mode of a washing machine (for example, a temperature is kept at from 40° C. through 60° C. for several hours). Moreover, packaging films for various containers, such as PET bottles for soft drinks, metal cans for cans of coffee etc., bottles of energy drinks or medical products, and bottles for beer, and packaging labels for use in the field of the POS system for fresh food, packed meals, premade meals, etc. are desired to have all of ethanol resistance, temperature and humidity resistance, wet abrasion resistance, and heat resistance, as well as the above-mentioned hot water resistance and water resistance. In order to improve water resistance of an image arca, therefore, proposed are, for example, adding polyvinyl alcohol and a polyamide epichlorohydrin resin to a thermosensitive recording layer, using hydrophobic resin emulsion, such as vinyl acetate emulsion, acrylic emulsion, and SBR latex, as a binder of a thermosensitive recording layer, or using a non-phenolic color developer that does not include a phenol-based compound as a color developer of a thermosensitive recording layer (see, for example, PTL 1). CITATION LIST Patent Literature PTL 1: Japanese Patent No. 6,751,479 SUMMARY OF INVENTION Technical Problem The present disclosure has an object to provide a thermosensitive recording medium that can form an image of high concentration, as well as having hot water resistance, water resistance, ethanol resistance, temperature-humidity resistance, wet abrasion resistance, and heat resistance. Solution to Problem According to one aspect of the present disclosure, a thermosensitive recording medium includes a support, and a thermosensitive recording layer disposed on or above the support. The thermosensitive recording layer includes a compound represented by General Formula (1) and a styrene-acryl resin. In General Formula (1), R2 is a C1-12 straight-chain, branched-chain, or alicyclic alkyl group, a C1-12 alkoxy group that is unsubstituted or substituted with a C1-12 alkyl group, a C7-12 aralkyl group that is substituted with a C6-12 aryl group or a halogen atom, or a C6-12 aryl group that is unsubstituted or substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom, where two or more R2 may be identical to or different from each other; and A1 is a hydrogen atom or a C1-4 alkyl group, where two or more A1, may be identical to or different from each other. Advantageous Effects of Invention The present disclosure can provide a thermosensitive recording medium that can form an image of high concentration, as well as having hot water resistance, water resistance, ethanol resistance, temperature-humidity resistance, wet abrasion resistance, and heat resistance. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic cross-sectional view illustrating an example of the thermosensitive recording medium according to the first embodiment. FIG. 2 is a schematic cross-sectional view illustrating an example of the thermosensitive recording medium according to the second embodiment. FIG. 3 is a schematic cross-sectional view illustrating an example of the thermosensitive