Leuco dyes and recording materials using the same

• US 5,024,699 A
• Filed: 03/02/1990
• Issued: 06/18/1991
• Est. Priority Date: 05/30/1987
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Iiyama, Kiyotaka, Kodera, Kaoru, Miyazaki, Osamu, Nakata, Masahiro, Hayakawa, Kunio
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): Klemanski, Helene
• Application Number:
  US07/487,138
• Time in Patent Office: 473 Days
• Field of Search: 106/21, 8/636, 8/649, 8/651, 260/350 L, 503/218
• US Class Current: 106/31.2
• CPC Class Codes: B41M 5/136 Organic colour formers, e.g. leuco dyes
• CPC Class Codes: C09B 23/141 Bis styryl dyes containing two radicals C6H5-CH=CH-
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture

Abstract

A leuco dye having the formula ##STR1## wherein R¹, R², R³ and R⁴ each represent a lower alkyl group; R⁵ represents an α-naphthyl group, β-naphthyl group or ##STR2## wherein R⁶ represents --NHCOR⁹, a halogen or an amino group which is unsubstituted or substituted by one or two C₁ -C₄ alkyl groups which are the same or different; and R⁷, R⁸ and R⁹ each represent hydrogen or a lower alkyl group, provided that when both R⁷ and R⁸ are hydrogen, R⁶ represents --NHCOR⁹ or bromine.

These dyes absorb in the near-infrared region and yield colored images with a color developer therefor with excellent preservability.

Claims

1. A leuco dye having the formula (I), ##STR12## wherein R¹, R², R³ ad R⁴ each represent a lower alkyl group;

R⁵ represents an α

-naphthyl group, β

-naphthyl group or ##STR13## wherein R⁶ represents --NHCOR⁹, a halogen or an amino group which is unsubstituted or substituted by one or two C₁ -C₄ alkyl groups which are the same or different; and

R⁷, R⁸ and R⁹ each represent hydrogen or a lower alkyl group, provided that when both R⁷ and R⁸ are hydrogen, R⁶ represents --NHCOR⁹ or bromine.

2. The leuco dye as claimed in claim 1, wherein R⁵ represents ##STR14## and R⁷ and R⁸ and R⁹ each represent hydrogen or a lower alkyl group.

3. The leuco dye as claimed in claim 1, wherein said lower alkyl group represented by R⁷ and R⁸ is an alkyl group having 1 to 4 carbon atoms.

4. The leuco dye as claimed in claim 2, wherein said alkyl group represented by R⁷, R⁸ and R⁹ is an alkyl group having 1 to 4 carbon atoms.

5. The leuco dye as claimed in claim 1, wherein R⁵ represents an α

-naphthyl group or β

-naphthyl group, and R⁷ and R⁸ each represent hydrogen or a lower alkyl group.

8. The leuco dye as claimed in claim 1, which is selected from the group consisting of:

##STR19##

6. A dye-containing composition, comprising:

a) one or more leuco dyes having the formula (I);

##STR15## wherein R¹, R², R³ and R⁴ each represents a lower alkyl group;

R⁵ represents an α

-naphthyl group, β

-naphthyl group or ##STR16## wherein R⁶ represents --NHCOR⁹, a halogen or an amino group which is unsubstituted or substituted by one or two C₁ -C₄ alkyl groups which are the same or different; and

R⁷, R⁸ and R⁹ each represent hydrogen or a lower alkyl group, provided that when both R⁷ and R⁸ are hydrogen, R⁶ represents --NHCOR⁹ or bromine; and

b) one or more other leuco dyes capable of correcting the color tone or the light absorbing properties of the leuco dye or dyes of the formula (I).

7. A dye-containing composition, comprising:

one or more leuco dyes having the formula (I);

##STR17## wherein R¹, R², R³ and R⁴ each represents a lower alkyl group;

R⁵ represents an α

-naphthyl group, β

-naphthyl group or ##STR18## wherein R⁶ represents --NHCOR⁹, a halogen or an amino group which is unsubstituted or substituted by one or two C₁ -C₄ alkyl groups which are the same or different; and

R⁷, R⁸ and R⁹ each represent hydrogen or a lower alkyl group, provided that when both R⁷ and R⁸ are hydrogen, R⁶ represents --NHCOR⁹ or bromine; and

b) one or more electron acceptor-color developers capable of rapidly inducing a coloring reaction when in contact with the leuco dyes of the formula (I).