Thermochromic materials

• US 4,028,118 A
• Filed: 12/23/1975
• Issued: 06/07/1977
• Est. Priority Date: 05/30/1972
• Status: Expired due to Term

• Current Assignee: The Pilot Ink Co. Ltd (Berkshire Hathaway Incorporated)
• Original Assignee: The Pilot Ink Co. Ltd (Berkshire Hathaway Incorporated)
• Inventors: Inagaki, Hiroshi, Kataoka, Takashi, Nakasuji, Norikazu, Nakashima, Sunao
• Primary Examiner(s): Morris, Theodore
• Application Number:
  US05/643,656
• Time in Patent Office: 532 Days
• Field of Search: 106/21, 106/31, 106/27, 106/231, 428/913
• US Class Current: 106/31.19
• CPC Class Codes: B41M 5/305 with reversible electron-donor electron-acceptor compositions
• CPC Class Codes: C08K 5/0041 Optical brightening agents, organic pigments
• CPC Class Codes: C09D 11/50 Sympathetic, colour changing or similar inks
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10T 428/24835 including developable image or soluble portion in coating or impregnation [e.g., safety paper, etc.]

Abstract

An excellent thermochromic material exhibiting a sharp and reversible metachromatism at temperatures within a range of from -40° to 80° C can be formed from (A) an electron-donating, chromatic organic compound; (B) a compound containing a phenolic hydroxyl group; (C) a compound selected from the group consisting of higher aliphatic monovalent alcohols; and (D) a compound selected from the group consisting of higher aliphatic monovalent acid alcohol esters. The excellent thermochromic characteristics of such a thermochromic material can be further improved when it is occluded in fine microcapsules having a size not exceeding 50 μ. Thermochromic polymers, thermochromic printing inks, thermochromic writing instruments, thermochromic paints and thermochromic sheets having excellent thermochromatic characteristics and wide utility can be prepared from such a thermochromic material or microencapsulated thermochromic material.

Claims

1. A reversible thermochromic material comprising (A) from about 1% to about 20% by weight of one or more electron-donating, chromatic organic compounds selected from the group consisting of diaryl phthalides, polyaryl carbinols, leuco auramines, lactum leuco compounds, indolines, spiropyrans and fluoranes having a molecular weight of from about 350 to about 1...;

(B) from about 2% to about 30% by weight of one or more compounds having a phenolic hydroxyl group and a molecular weight of from about 200 to about 800;

(C) from about 10% to about 90% by weight of one or more compounds selected from the group consisting of lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, docosyl alcohol, oleyl alcohol and mixtures thereof; and

(D) the balance to make 100% being one or more compounds selected from the group consisting of octyl caprylate, decyl caprylate, octyl caprate, decyl caprate, cetyl caprate, stearyl caprate, butyl laurate, octyl laurate, lauryl laurate, stearyl laurate, butyl myristate, decyl myristate, myristyl myristate, cetyl myristate, octyl palmitate, butyl stearate, decyl stearate, lauryl stearate, stearyl stearate, 12-hydroxy stearic acid triglyceride and mixtures thereof, said component (C) and (D) controlling the temperature and sensitivity of coloration/decoloration of said thermochromic material undergoing reversible metachromatism at a temperature within the range of from about -40°

to about 80°

C.

2. A thermochromic material as set forth in claim 1 wherein component (A) is selected from the group consisting of fluoran leuco compounds substituted with N-substituted amino groups, triphenyl methane phthalide leuco compounds and fluroan-γ

-lactam leuco compounds

3. A thermochromic material as set forth in claim 1 wherein component (B) is selected from the group consisting of alkyl-monophenols, alkyl-diphenols, thio-bis-alkyl-phenols, alkylphenylphenols, alkylcatechols, hydroxyalkylnaphthalenes, dihydroxyalkylnaphthalenes wherein any alkyl moiety has 1 to 12 carbon atoms, gallic acid alcohol esters, p-oxybenzoic acid alcohol esters, protocatechuic acid alcohol esters and phenol-formaldehyde prepolymers.

4. A thermochromic material as set forth in claim 1 wherein the ratio of component (C) to component (D) is from about 9:

1 to about 4;

6 by weight.

5. A thermochromic material undergoing reversible metachromism at a temperature within the range of from about 40 to about 80°

C, as set forth in claim 1 wherein component (C) controlling the temperature of coloration/decoloration of said thermochromic material is selected from the compounds consisting of docosyl alcohol, stearyl alcohol, cetyl alcohol and mixtures thereof, and component (D) controlling the sensitivity and the temperature of coloration/decoloration of said thermochromic material is selected from the compounds consisting of stearyl stearate, lauryl stearate, cetyl myristate, myristyl myristate, stearyl laurate, stearyl caprate, 12-hydroxy stearic acid triglyceride and mixtures thereof, wherein the ratio of compoent (C) to component (D) is from about 9;

1 to about 4;

6 by weight.

6. A thermochromic material undergoing reversible metachromism at a temperature within the range of from about 20°

to about 40°

C, as set forth in claim 1 wherein component (C) controlling the temperature of coloration/decoloration of said thermochromic material is selected from the compounds consisting of cetyl alcohol, myristyl alcohol and mixtures thereof, and component (D) controlling the sensitivity and the temperature of coloration/decoloration of said thermochromic material is selected from the compounds consisting of lauryl stearate, decyl stearate, butyl stearate, octyl palmitate, cetyl myristate, myristyl myristate, decyl myristate, stearyl laurate, lauryl laurate, stearyl caprate, cetyl caprate and mixtures thereof, wherein the ratio of component (C) to component (D) is from about 9;

1 to about 4;

6 by weight.

7. A thermochromic material undergoing reversible metachromism at a temperature within the range of from about 0 to about 20°

C, as set forth in claim 1 wherein component (C) controlling the temperature of coloration/decoloration of said thermochromic material is selected from the group consisting of myristyl alcohol, lauryl alcohol and mixtures thereof, and component (D) controlling the sensitivity and the temperature of coloration/decoloration of said thermochromic material is selected from the group consisting of butyl stearate, octyl palmitate, decyl myristate, butyl myristate, lauryl laurate, octyl laurate, decyl caprate and mixtures thereof, wherein the ratio of component (C) to component (D) is from about 9;

1 to about 4;

6 by weight.

8. A thermochromic material undergoing reversible metachromism at a temperature within the range of from about -20 to about 0°

C, as set forth in claim 1 wherein component (C) controlling the temperature of coloration/decoloration of said thermochromic material is selected from the group consisting of lauryl alcohol, oleyl alcohol and mixtures thereof, and component (D) controlling the sensitivity and the temperature of coloration/decoloration of said thermochromic material is selected from the group consisting of butyl myristate, octyl laurate, butyl laurate, decyl caprate, octyl caprate, decyl caprylate and mixtures thereof, wherein the ratio of component (C) to component (D) is from about 9;

1 to about 4;

6 by weight.

9. A thermochromic mateiral undergoing reversible metachromism at a temperature within the range of from about -40°

to about -°

C, as set forth in Claim 1 wherein component (C) controlling the temperature of coloration/decoloration of said thermochromic material is oleyl alcohol, and component (D) controlling the sensitivity and the temperature of coloration/decoloration of said thermochromic material is selected from the group consisting of butyl myristate, butyl laurate, octyl caprate, decyl caprylate, octyl caprylate and mixtures thereof, wherein the ratio of component (C) to component (D) is from 9;

1 to about 4;

6 by weight.