Image-recording medium containing self-developing leuco dye

Details Image-recording medium containing self-developing leuco dye Image-recording medium containing self-developing leuco dye

2000-03-30

2002-08-13

Hess, Bruce H. (Department: 1774)

Record receiver having plural interactive leaves or a colorless

Having a colorless color-former, developer therefor, or...

Identified color-former

C503S222000, C503S223000, C503S224000, C549S330000

Reexamination Certificate

active

06432876

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a novel acid-sensitive leuco dye having markedly improved coloring property, to a high sensitivity image-recording medium containing the same and to a high sensitivity chemical amplification type image-recording medium further combined with an acid generator.
BACKGROUND OF THE INVENTION
Leuco dyes which develop color by reacting with acidic developers are broadly used in heat sensitive paper and pressure sensitive paper, and those which develop color in almost all hues such as yellow~orange~red~purple~blue~green~black~near infrared have so far been known. The development of such colors is principally an equilibrium reaction of an acid (developer) and a base (leuco dye), so that an acidic developer such as a bisphenol derivative is generally used in large excess in order to obtain sufficient coloring density.
Since addition of a developer in large excess leads to the increased coating thickness and therefore is disadvantageous in terms of resolution, great concern has been directed toward the improvement of coloring property of leuco dyes and development of a leuco dye capable of developing color with single molecule.
A xanthene based leuco dye in which hydroxyl group is protected with allyl group has been described by M. Inoue et al. in
Angew. Chem. Int. Ed. Engl.,
31, 204 (1992). When said leuco dye is heated, Claisen rearrangement of allyl group occurs to cause transfer of electron and proton from the thus formed hydroxyl group to the phthalide moiety, thus resulting in the opening of the lactone ring to form a quinoid structure, so that it develops orange color by single molecule without adding a developer.
Also, U.S. Pat. No. 5,243,052 describes a quinophthalone dye protected with t-Boc group. In said compound, hydroxyl group is formed when the protecting group is removed upon heating the compound and bound to the quinoline ring through hydrogen bond, so that it develops a color by itself.
However, these dyes cannot be regarded as techniques which can correspond to every hue and have a disadvantage of being low in heat sensitivity.
On the contrary, there are no reports on the technique for developing color with single molecule by generating an acid group such as carboxyl group, sulfo group or phosphono group in the molecule to form an intramolecular salt.
On the other hand, JP-A-5-281654 (the term “JP-A” as used herein means an “unexned published Japanese patent application”) describes a leucoindigo/thioindigo compound which develops color by the removal of t-Boc group, as a leuco dye which develops color by chemical amplification in combination with a photo acid generator.
Also, as a technique in which a leuco dye that develops color by the action of an acidic developer is colored by a chemical amplification system, there are descriptions in U.S. Pat. Nos. 5,286,612, 5,395,736 and 5,441,850, JP-W-8-503081 and JP-W-8-503082 (the term “JP-W” as used herein means an “unexamined published Japanese international patent application”), regarding recording materials in which a secondary acid generator which generates a secondary acid (developer) by the action of a superacid generator and a superacid is used in combination with a leuco dye. In this case, a developer (secondary acid) is generated by an amplified manner in an amount sufficient enough for developing color of the leuco dye when heated, only in a region where an actinic ray is applied, and the color is developed by its interlayer mixing with the leuco dye coated on another layer.
Recording materials which use such an acid amplification have a problem in that their sensitivity is reduced in the case of a leuco dye having a basic group such as amino group which inhibits acid amplification.
For example, the former leucoindigo compound is low in sensitivity due to the action of nitrogen atom to inhibit acid amplification, and the latter case requires coating of the secondary acid generator and leuco dye on different layers.
Though most of the leuco dyes which develop cyan~black colors have amino group, a spiropyran compound has been disclosed as a structure which does not have amino group but develops color by an acidic developer, for example in JP-A-49-2545, JP-A-57-191634, JP-A-60-27589, JP-A-63-41846 and British Patent 1,359,472. The present inventors have found that acid amplification inhibition of this compound was small, but its coloring property by the acidic developer was low, so that further improvement was required because of the necessity to use large excess of the developer in order to obtain sufficient coloring density.
In addition, great concern has been directed toward the development of a leuco dye which shows low acid amplification inhibition, does not require a developer and develops blue color by itself.
SUMMARY OF THE INVENTION
The object of the present invention is to provide first a leuco dye having improved coloring property, which develops color even by single molecule without requiring excess amount of a developer, secondly an image-recording medium which contains the same to effect high sensitivity and excellent resolution and thirdly an image-recording medium which shows high sensitivity even in an image forming method in which an acid generator is used.
The object of the present invention has been achieved by the following items 1) to 8).
1) An image-recording medium which comprises a leuco dye represented by the following general formula (1):
LD—(A—P
1
)
n
  (1)
wherein LD represents an acid-sensitive leuco dye mother nucleus, —A represents the residue of an acidic group (—AH) selected from —SO
3
H, —CO
2
H and —P(═O)
x
R
y
, R represents a hydrogen atom or a substituent group, x and y are x=1 and y=1 or x=2 and y=0, P
1
represents a protecting group which can be removed by the action of light, heat or acid, and n is an integer of 1 or more.
2) The image-recording medium according to the above item 1), wherein LD is a spiropyran derivative.
3) The image-recording medium according to the above item 1) or 2) , wherein the leuco dye of general formula (1) has apolymerizable group at a substitutable position and is forming a copolymer with a monomer having a partial structure which generates acid by the action of light, heat or acid.
4) The image-recording medium according to any one of the aforementioned items 1) to 3), wherein it further comprises an acid generator which generates acid by the action of light or heat.
5) The image-recording medium according to any one of the aforementioned items 1) to 4), wherein it further comprises a compound which newly generates acid by the action of acid.
6) The image-recording medium according to any one of the aforementioned items 1) to 5), wherein it further comprises an infrared absorbing substance.
7) A leuco dye represented by the aforementioned general formula (1).
8) A leuco dye according to the above item 7), wherein LD is a spiropyran derivative.
Other objects and advantages of the present invention will be made apparent as the description progresses.
DETAILED DESCRIPTION OF THE INVENTION
In the general formula (1), ID represents a colorless or hypochromic acid-sensitive leuco dye mother nucleus which develops color by reacting with an acidic developer. Known leuco dyes are described in detail in, for example, Moriga and Yoshida, “Dyes and Drugs” (written in Japanese), 9, p. 84 (Chemical and Synthetic Industry Association, 1964); “New Edition Dye Handbook” (written in Japanese) ,p. 242 (Maruzen, 1970); R. Garner, “Reports on the Progress of Appl. Chem.”, 56, p. 199 (Maruzen, 1974); “Memory, Recording and Sensitive Materials” (written in Japanese), p. 144 (Gakujutsu Publication Center, 1985; and U.S. Pat. Nos, 5,243,052 and 4,826,976.
Acid-sensitive leuco dyes are broadly used in pressure sensitive paper and heat sensitive paper, and those which develop color in almost all hues such as yellow~orange~red~purple~blue~green~black~near infrared have so far been known. From the structural point of view, those which have various nuclei are also known, such as of

Affiliated with

Also associated with

Rating

Image-recording medium containing self-developing leuco dye does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Image-recording medium containing self-developing leuco dye, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image-recording medium containing self-developing leuco dye will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2909316