Heat-sensitive recording material

Details Heat-sensitive recording material Heat-sensitive recording material

1999-10-18

2001-07-17

Hess, Bruce H. (Department: 1774)

Record receiver having plural interactive leaves or a colorless

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

Spatial relationship specified between color-former and...

C503S200000

Reexamination Certificate

active

06261993

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material which comprises a support and a heat-sensitive recording layer and a protective layer which are provided on the support, and which is excellent in transparency, glossiness, and light-fastness, and which is excellent in scratch resistance because the heat-sensitive recording material has a protective layer which is excellent in friction resistance and lubricity with respect to a heat-sensitive recording head so that adhesion of the heat-sensitive recording material to the heat-sensitive recording head or the like and deposition of foreign matters thereon can be prevented.
2. Description of the Related Art
Heat-sensitive recording has been recently developing because the device used for the heat-sensitive recording is structured simply, is highly reliable, and does not need complicated maintenance. As a heat-sensitive recording material, conventionally, compounds obtained through the reaction of an electron donative colorless dye and an electron acceptive compound, and compounds obtained through the reaction of a diazonium salt compound and a coupler are widely known.
In recent years, in order to improve properties including color developing density and color developing sensitivity, fastness of a color developer and the like in heat-sensitive recording materials, extensive studies have been carried out. However, when a heat-sensitive recording material is exposed to sunlight or displayed on walls at offices or the like for a long period of time, there have been drawbacks in that background portions of the material become colored through irradiation of light, and image areas may become discolored or faded. In order to limit the discoloring or fading of image areas, various methods have been proposed. However, these methods fail to provide sufficient results.
On the other hand, in many fields such as facsimiles, printers, labels, and the like, demand for a heat-sensitive recording system is increasing. Accordingly, there is a great demand for a heat-sensitive recording material of higher performance. Image recording of the heat-sensitive recording material is carried out by a heat-sensitive recording head through imagewise heating. In order to print an image on a heat-sensitive recording material in a smooth manner without printing failures and obtain a high quality image which is excellent in glossiness, it is desired to decrease kinetic friction between the heat-sensitive recording material and the heat-sensitive recording head to a certain value or less.
Conventionally, in order to impart friction resistance and lubricity to a heat-sensitive recording material, waxes (e.g., zinc stearic acid or the like), matifying agents, pigments, and the like have been used. However, such means as described above fail to sufficiently provide improvements in friction resistance and lubricity. In addition, if the heat-sensitive recording material is a reflecting material, transparency and glossiness thereof decrease (if the heat-sensitive recording material is a transparent material, the haze degree thereof increases). Further, there have been drawbacks in that these compounds become fused to a heat-sensitive recording head, a printed surface, and the like so that failures such as deposition of foreign matters, unevenness in glossiness, and the like are caused to the heat-sensitive recording material.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a heat-sensitive recording material which is excellent in transparency, glossiness, and light-fastness and which is excellent in scratch resistance because the heat-sensitive recording material has a protective layer which is excellent in friction resistance and lubricity with respect to a heat-sensitive recording head, thus preventing adhesion of the heat-sensitive recording material to a heat-sensitive recording head or the like and deposition of foreign matters thereon.
In order to accomplish the above-described object, the present inventors carried out extensive studies, and found that addition of a long chain alkyl ether denatured polyvinyl alcohol to a protective layer provides very good results, thus achieving the present invention.
That is, the heat-sensitive recording material according to the present invention comprises a support, and a heat-sensitive recording layer and a protective layer which are provided on this support, wherein the protective layer is formed by at least a long chain alkyl ether denatured polyvinyl alcohol. Preferably, this long chain alkyl ether denatured polyvinyl alcohol is an alkyl ether denatured polyvinyl alcohol having 8 to 20 carbon atoms. More preferably, it is a polymer represented by the following formula (A).
wherein R
1
represents a hydrogen atom, a methyl group, or —CH
2
CO
2
M; R
2
represents a hydrogen atom or —CO
2
M; R
3
represents a hydrogen atom, —CO
2
M, an amino group, an amide group, a substituted amide group, a hydroxy group, a glycidyl group, a sulfonic group, a polyethylene oxide group, a polypropylene oxide group, or a group including functional groups of these groups; R
4
represents a hydrogen atom or a methyl group; R
5
represents an alkyl group having 8 to 20 carbon atoms; M represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, Na, K, or Li; and each of n, x, y, and z represents a polymerization degree.
Further, preferably, the protective layer in the heat-sensitive recording material of the present invention is formed by using at least a long chain alkyl ether denatured polyvinyl alcohol and another water-soluble binder. As the another water-soluble binder, preferably, a silicone denatured polymer or gelatin is used. Further, in the heat-sensitive recording material of the present invention, preferably, the protective layer contains inorganic ultra-fine grains. Moreover, preferably, the protective layer contains dialkyl starch as a crosslinking agent.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A preferred embodiment of a heat-sensitive recording material according to the present invention will be explained hereinafter.
The heat-sensitive recording material of the present invention comprises a support and a heat sensitive recording layer and a protective layer which are provided on the support. The protective layer is formed by using at least a long chain alkyl ether denatured polyvinyl alcohol.
Preferably, the long chain alkyl ether denatured polyvinyl alcohol is alkyl ether denatured polyvinyl alcohol having 8 to 20 carbon atoms, and more preferably, is a polymer represented by the following formula (A):
wherein R
1
represents a hydrogen atom, a methyl group, or —CH
2
CO
2
M, R
2
represents hydrogen atom or —CO
2
M, R
3
represents a hydrogen atom, —CO
2
M, an amino group, an amide group, a substituted amide group, a hydroxy group, a glycidyl group, a sulfonic group, a polyethylene oxide group, a polypropylene oxide group, or groups including these functional groups, R
4
represents a hydrogen atom or a methyl group. Preferably, each of R
1
, R
2
, and R
4
is a hydrogen atom, and R
3
is —CO
2
M as a combination, or each of R
2
and R
4
is a hydrogen atom, R
1
is —CH
2
CO
2
M, and R
3
is —CO
2
M as a combination.
M represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, Na, K, or Li.
R
5
represents a long chain alkyl group, i.e., an alkyl group having 8 to 20 carbon atoms. An alkyl group may have a straight or branched chain, or it may have a substituted group such as an aryl group. Among these, from a viewpoint of lubricity, an alkyl group having 8 to 16 carbon atoms is more preferable, and a dodecyl group having 12 carbon atoms is particularly preferable.
Each of n, x, y, and z represents a polymerization degree. Preferably, n ranges from 0 to 20, and more preferably, from 0 to 10. When the value of n is large, the number of acid groups increases so that compatibility of the polymer with gelatin thereby improve

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