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
2001-09-07
2003-12-09
Hess, B. Hamilton (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
06660689
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording material, and in particular, to a recording material which can be recorded by being heated or by pressure being applied thereto.
2. Description of the Related Art
Recording materials on which an image is recorded by heat being applied thereto by a thermal head or the like have come into wide use in recent years as the recording devices therefor are simple, reliable and do not require maintenance.
Such recording materials are formed to include, on a support, a recording layer which contains, as color forming components, for example, an electron donating dye precursor and an electron receiving compound, or a diazonium salt compound and a coupler. An image is recorded by utilizing a color forming reaction of the color forming components which proceeds due to the application of heat.
In such a heat-sensitive type recording method (heat-sensitive recording), an image is recorded due to the application of heat. Thus, the surface temperature of the recording material at the time of image recording is high (e.g., a maximum of about 200° C. or more when a thermal head is used).
In heat-sensitive recording, in a case in which, for example, heat is applied continuously at a high temperature, the moisture in the recording layer vaporizes and moves toward the support. Due to water vapor and gasses accumulating at portions of the boundary surface between the recording layer and the support, so-called blistering occurs, in which the support and the recording layer deform. The occurrence of such blistering and the like results in a deterioration in the quality of the image surface and in the quality of the material on which the image is recorded, such that defects arise at the image printed surface (hereinafter, “image printed surface defects”).
As a means for preventing image printed surface defects such as blistering in which the support and the like deform due to the accumulation of water vapor or the like generated from the recording layer as described above, there is a method of interposing, at the boundary surface between the recording layer and the support, a layer having low permeability with respect to gas water vapor, e.g., a resin layer containing a binder such as polyvinyl alcohol or mica or the like. However, if the formed resin layer is not uniform and flat, the flatness of the surface of the recording layer which is formed on the resin layer is poor, which leads to a deterioration in image quality, such as non-uniform color, and the quality of the recording material deteriorates.
Accordingly, in order for the resin layer to be formed uniform and flat, the viscosity of a coating solution for resin layer formation must be a low viscosity which allows the coating solution, after being coated, to level so as to form a flat surface. “Leveling” means that the unevenness of the coated film surface formed by the coating solution being applied, i.e., film thickness differences of the coated film, becomes uniform and flat due to the weight thereof, during the period of time from coating to drying.
From the standpoints of convenience of handling and the like, a water soluble resin such as polyvinyl alcohol (PVA) or the like is used in a binder. Conventionally, PVA coating solutions were usually prepared by using water as the solvent. However, when water alone is used as the solvent, it is not possible to obtain a coating solution of a low viscosity to an extent at which the above-described leveling can be expected. Further, in this process, it is difficult to appropriately control the viscosity of the coating solution, and application by, for example, a gravure coating method or the like, is difficult. Moreover, when the viscosity of the coating solution is high, a long time is required for drying, such that the burden of the drying process is large. On the other hand, if the coating solution is diluted to a viscosity which permits leveling and easy formation of a good film surface, the concentration of the binder component in the coating solution becomes too low, and a problem arises in that, even if the solution is coated, the desired resin layer cannot be obtained. Namely, it is difficult to easily form a resin layer which has a desired film thickness and in which a sufficient reduction in gas permeability is possible.
As described above, a coating solution for formation of a resin layer, which contains a high concentration of a water soluble resin such as PVA and which has a low viscosity to an extent that leveling can be expected, has not yet been developed. Accordingly, it is currently the state that a recording material which has between the recording layer and the support a resin layer which is uniform, has a flat surface, and has excellent gas blocking ability has not yet been obtained.
SUMMARY OF THE INVENTION
The present invention overcomes the above-described drawbacks of the conventional art, and achieves the following object. Namely, an object of the present invention is to provide a recording material in which image defects such as non-uniform color do not arise, and which has a resin layer which has an excellent gas blocking ability and is flat, and which is formed by a coating solution having a high concentration of a water soluble resin such as PVA and a low viscosity which enables formation of a flat surface due to leveling.
A recording material of the present invention has a support; a recording layer which can form color due to application of heat and/or pressure thereto; and, between the support and the recording layer, at least one layer (resin layer) containing polyvinyl alcohol. It is preferable that the degree of saponification of the polyvinyl alcohol is 30 mol % to 90 mol %, and that the degree of polymerization of the polyvinyl alcohol is 1000 or less.
Further, a recording material of the present invention has a support; a recording layer which can form color due to application of heat and/or pressure thereto; and, between the support and the recording layer, a resin layer formed by coating a coating solution which is prepared by dissolving polyvinyl alcohol in a mixed solvent whose ratio (mass ratio) of a contained amount of alcohol with respect to water is 1 or less.
Moreover, a recording material of the present invention has a support; a layer (resin layer) containing polyvinyl alcohol and provided on the support; and a recording layer provided on the resin layer, wherein the resin layer is a resin layer formed by processes of dissolving polyvinyl alcohol in a mixed solvent of water and alcohol, adding methanol to an obtained solution to adjust a viscosity to a desired viscosity, coating an obtained coating solution on the support, and drying a coated layer. The viscosity at 40° C. of the coating solution is preferably 5 to 100 mPa·s.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The recording material of the present invention is formed by forming, by coating, a resin layer by using a coating solution which has polyvinyl alcohol as a binder component and which is prepared by dissolving the polyvinyl alcohol in a mixed solvent of alcohol and water.
Hereinafter, the recording material of the present invention will be described in detail.
Note that, in the present application, numerical ranges are to be interpreted as encompassing both the minimum value and the maximum value stated for the range.
<<Recording Material>>
The recording material of the present invention includes, on a support, a recording layer which can form color due to application of heat and/or pressure, and at least one layer (hereinafter, “resin layer”) containing polyvinyl alcohol, and, if needed, other layers such as a protective layer or the like.
[Resin Layer]
The resin layer contains, as a binder and as the main component thereof, polyvinyl alcohol (hereinafter, “PVA”), and preferably contains a water swellable synthetic mica. If necessary, the resin layer may contain other components such as gelatin, a hardening agent, a surfactant, a water soluble resin other than PVA,
Ogata Yasuhiro
Serizawa Shinichiro
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