Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or... – Identified color-former
Reexamination Certificate
2002-06-13
2004-04-13
Edwards, N. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
Identified color-former
C503S200000
Reexamination Certificate
active
06720287
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat-sensitive recording material and a microcapsule solution, and more particularly relates to a diazo-compound-based heat-sensitive recording material that is fixable and superior in shelf life, and a microcapsule solution used in the heat-sensitive recording material.
2. Description of the Related Art
A heat-sensitive recording material, which has images recorded thereon by applying heat applied thereto with a thermal head or the like, is comparatively inexpensive, and recording devices therefor are simple, highly reliable and do not require maintenance.
Under the condition, particularly in recent years, there has been a strong demand to make this recording material high performance by improving high image quality and storage stability and the like. Research has been vigorously carried out on properties, such as coloring density, image quality and shelf life, of the heat-sensitive recording material.
However, in general, in the case of a heat-sensitive recording material containing a diazonium salt compound as coloring component, since the activity of the diazonium salt compound is very high, the diazonium salt compound gradually thermal decomposes, even in a dark place, and loses reactivity. The resulting disadvantage is a short shelf life as the heat-sensitive recording material. Moreover, when a diazonium salt compound is decomposed, various products of a photodecomposition reaction are generated. Thus, a coloring, which is called a photodecomposition stain, is easily generated, causing serious degradation in whiteness in base surface portions.
One of the methods for solving this disadvantage is to encapsulate the diazonium salt compound into microcapsules. This method separates the diazonium salt compound from water, bases and the like, which accelerating decomposition. Therefore, it is possible to greatly improve the shelf life as the recording material (see, Usami, Tomomasa, et al. Journal of Electronic Photographic Society, Vol. 26, 2 (1987) pp. 115 to 125).
Moreover, when the glass transition temperature of the capsule wall is slightly higher than room temperature (thermal responsive microcapsules), the capsule exhibits a substance non-permeability at room temperature, while it exhibits a substance permeability at temperatures higher than the glass transition temperature. For this reason, by encapsulating the diazonium salt compound using the above-mentioned capsule wall with a coupler, a base and the like being disposed outside the capsule, it is possible to store the diazonium salt compound stably for a long time, to easily form colored images by heating the microcapsules and also to fix (photo-fix) the images through light irradiation.
However, the decomposition of the diazonium salt compound cannot be completely prevented even by using the microcapsules. It is not possible to avoid the coloring due to photodecomposition stain caused by the existence of various photodecomposition products. This results in degradation in whiteness of the recording surface of the heat-sensitive recording material, causing not only degradation in the recording material, but also serious reduction in the image contrast due to the high base surface density in a resulting image, and a resultant degradation of the image quality.
However, if one simply reduces the reactivity of the diazonium salt compound, the coloring density tends to be lowered as well. Therefore, it is necessary to improve the whiteness while maintaining the coloring property.
In recent years, in order to solve these problems with coloring, increasing the whiteness in a recording surface to be recorded and the stability in storage (shelf life, herein shelf life refers to shelf life of an unrecorded recording material) with respect to the whiteness, and improving the whiteness in non-image portions (base surface portion) after recording (after photo-fixing),various research has been performs.
For example, Japanese Patent Application Laid-Open (JP-A) No. 8-324129 has proposed a technique in which an aromatic carboxylate such as diphenylphthalate, is encapsulated in a microcapsule together with a diazonium salt compound.
When the aromatic carboxylate is encapsulated in the microcapsule together with the diazonium salt compound, and utilized, it becomes possible to reduce the generation of photodecomposition stain, and also to provide a heat-sensitive recording material that has superior shelf life and base surface coloring. However, a solution which contains the microcapsules (hereinafter, referred to as “microcapsule solution”), which is encapsulated the diazonium salt compound and the aromatic carboxylate such as diphenylphthalate, has a problem in that, as time passes, the deposition of crystals occurs during the storage, etc. These crystals cause various problems. For example, when a microcapsule solution, which contains crystals that have grown to approximately dozens of microns, is used as a coating solution, and applied as it is, there is a significant degradation of the coated surface. Therefore, in order to ensure a uniform coated surface, the coating solution comprising the microcapsule solution is coated after the above-mentioned crystals and the like have been removed using a filter having a mesh size of several microns to dozens of microns. However, if a great amount of residue is filtered by the filtering process, that is, if there is a great amount of crystals, clogging occurs in the filter to cause a failure in transporting the solution, resulting in a deterioration of the quality of the recording material and the production efficiency.
SUMMARY OF THE INVENTION
Recently, there has been a strong demand for increasing high performance, such as high image quality and stability in storage (in particular, shelf life. However, at present a heat-sensitive recording material has not been provided, which: comprises a recording surface (base surface portion), which has high whiteness while maintaining coloring properties; has a superior storage stability, which does not damage the whiteness of the base surface portion for a long period of time; stably forms an image having high contrast with white non-image portions while suppressing crystallization when a microcapsule solution is being stored, to obtain superior production efficiency.
The present invention provides a heat-sensitive recording material which has the superior whiteness in the non-image portions (base surface portions) and storage stability (shelf life) with respect to the whiteness, and forms a clear image with high contrast in a stable manner, with high production efficiency, and a microcapsule solution which can reduce crystallization over time, and is superior in storage stability in order to solve the above-mentioned conventional problems.
The above-mentioned objects can be achieved by the following means.
A first aspect of the present invention provides a heat-sensitive recording material comprising: a substrate; a thermal recording layer disposed on said substrate, which thermal recording layer contains a diazonium salt compound and a coupler that has a coupling reaction with the diazonium salt compound to develop a color; an aromatic carboxylate represented by the following general formula (I); and an aromatic carboxylate represented by the following general formula (II); wherein the diazonium salt compound is encapsulated in microcapsules together with the aromatic carboxylate represented by the general formula (I) and the aromatic carboxylate represented by the general formula (II);
in which R
1
represents one of a halogen atom, an alkyl groups having 1 to 20 carbon atoms, an alkenyl groups having 2 to 20 carbon atoms, an aralkyl groups having 7 to 20 carbon atoms, an alkoxy groups having 1 to 20 carbon atoms, an alkylcarbonyl groups having 2 to 20 carbon atoms, an alkylcarbonyloxy groups having 2 to 20 carbon atoms, an alkyloxycarbonyl groups having 2 to 20 carbon atoms, a cycloakyl groups having 5 to 20 carbon atoms and an aryl groups having 6 to 20
Edwards N.
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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