Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or... – Spatial relationship specified between color-former and...
Reexamination Certificate
1999-10-14
2002-01-15
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
06339041
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 (1) color developing density and color developing sensitivity, (2) 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 objects, the present inventors carried out extensive studies, and found that a silicon denatured polymer and inorganic ultra-fine grains having a mean primary particle diameter which is less than or equal to 0.1 &mgr;m are added to a protective layer is effective, thus achieving the present invention.
That is, a 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 the support, wherein the protective layer contains at least a silicon denatured polymer and inorganic ultra-fine grains whose mean primary particle diameter is less than or equal to 0.1 &mgr;m. Preferably, this silicon denatured polymer is a silicon graft polymer. Preferably, the inorganic ultra-fine grains are of at least one selected from a group consisted of barium sulfate, zinc oxide, magnesium oxide, lead oxide, zirconium oxide, colloidal silica, or alumina. Among these compounds, colloidal silica, barium sulfate, and alumina are particularly preferable. In cases in which colloidal silica is used, preferably, colloidal silica and inorganic ultra-fine grains of another type mixed in a ratio of 1:9 to 6:4 (colloidal silica to the inorganic ultra-fine grains of another type) by weight are used in combination.
The protective layer can be formed by using in addition another water-soluble binder. As the another water-soluble binder, gelatin is preferable.
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 contains at least a silicon denatured polymer and inorganic ultra-fine grains having a mean primary particle diameter which is equal to or less than 0.1 &mgr;m.
In the present invention, the term inorganic ultra-fine grains refers to grains whose mean primary particle diameter is less than or equal to 0.1 &mgr;m. As long as the mean primary particle diameter of inorganic ultra-fine grains is 0.1 &mgr;m, there is no other limitations for the inorganic ultra-fine grains. However, preferably, the maximum particle diameter of the ultra-fine grains in a dispersion solution (which is a threshold value of the maximum particle diameter whose particle diameter distribution is larger in the dispersion solution) is equal to or less than 0.5 &mgr;m, more preferably, is equal to or less than 0.4 &mgr;m, and particularly preferably, is equal to or less than 0.35 &mgr;m. The frequency of (aggregated) grains whose particle diameter in the dispersed solution is equal to or more than 0.3 &mgr;m is equal to or less than 5%, and preferably, is equal to or less than 1%. Particularly preferably, the frequency of (aggregated) grains whose particle diameter is equal to or more than 0.25 &mgr;m is equal to or less than 5%.
Particle diameters of the ultra-fine grains can be measured by a known method, for example, by using a COULTER N4 type sub-micron particle diameter analysis device (manufactured by Nikkaki-sha).
As the inorganic ultra-fine grains of the present invention, inorganic ultra-fine grains such as barium sulfate, zinc oxide, magnesium oxide, lead oxide, zirconium oxide, colloidal silica, or alumina are preferable. Among these compounds, barium sulfate, colloidal silica, and alumina are particularly preferable.
The above-described inorganic ultra-fine grains can be used singly, or two types of these compounds or more can be used in combination. Particularly, since colloidal silica is of high activity, when multiple layers are coated at the same time, due to a combination of layers, one layer may cause unevenness in coating by interacting with a compound of another layer, thus damaging the surface smoothness of the obtained heat-sensitiv
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