Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or...
Reexamination Certificate
2000-06-16
2002-05-28
Hess, Bruce (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
C427S152000, C503S226000
Reexamination Certificate
active
06395679
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat-sensitive recording material and a method for producing the same, and more specifically, to a heat-sensitive recording material which provides high quality images suitable for a recording medium used in the medical field and the like, and a method for producing the same.
2. Description of the Related Art
In recent years, heat-sensitive recording methods have come to be used more often in various fields because the methods have advantages such as: (1) developing processing is not necessary; (2) recording materials having a quality close to that of general use paper are obtained when paper is used as the substrate of the recording material; (3) handling is easy; (4) the densities of the formed colors are high; (5) simple, reliable and inexpensive recording apparatuses can be used; (6) noise is not generated during recording; and (7) no particular maintenance is required. Application of heat-sensitive recording methods is expanding, for example, to the fields of facsimiles, printers and the like and to the field of labels such as POS.
As a heat-sensitive recording material used for the heat-sensitive recording, heat-sensitive recording materials utilizing the reaction of colorless electron-donating dyes and electron-accepting compounds, heat-sensitive recording materials utilizing the reaction of diazo compounds and couplers, and the like have been widely known.
Under these circumstances, the development of a transparent heat-sensitive recording material which can be recorded directly by a thermal head has come to be desired recently so that the demand for recording multicolor images can be satisfied or recorded images can be projected by an overhead projector or can be directly observed on a light table.
Therefore, it has been proposed that a heat-sensitive recording material be prepared by disposing, on a transparent substrate such as a film of a synthetic polymer substance, a heat-sensitive recording layer which is formed by dispersing, in a binder as fine particles, a substantially colorless color forming component A and a substantially colorless color forming component B which forms color by reacting with the color forming component A or by micro-encapsulating either one of components A and B and using the other component in the form of an emulsion.
Although such a transparent heat-sensitive recording material has good transparency, there has been a drawback with the heat-sensitive recording material in that sticking tends to occur and noise tends to be generated when the heat-sensitive recording material is used for forming images by using a heat-sensitive recording apparatus such as a thermal recording printer. For the purpose of improving matching performance of such a thermal head, attempts have been made to provide a protective layer, which contains a pigment and a binder as main components, on the heat-sensitive recording layer of the heat-sensitive recording material, and to include various types of lubricants in the protective layer. However, a heat-melting lubricant such as derivatives of higher fatty acids has drawbacks such as: (1) the lubricant has insufficient lubricating property in regions in which the thermal energy is less than the amount required for melting; and (2) after being melted by thermal recording, the lubricant recrystallizes and the surface thereof whitens (i.e., bleeding is caused). On the other hand, when a liquid lubricant at an ordinary temperature is used, it is necessary to emulsify the lubricant to be added to the coating solution for the protective layer. Accordingly, there is a problem with liquid lubricants in that the emulsion is damaged by shear when passing through a pump or a filter while the liquid is being fed or is damaged by an ultrasonic deaerator, thereby resulting in minute coating defects due to repelling. When the image formed on such a heat-sensitive material is used for medical purposes, there is a risk that such coating defects may make diagnosis difficult and thus, improvements have been desired. The present situation is that a satisfactory heat-sensitive recording material having an excellent head matching performance and a surface which is coated well without any coating defects has not yet been achieved.
SUMMARY OF THE INVENTION
A purpose of the present invention is to solve the above-described conventional problems and to achieve the following objects. That is, an object of the present invention is to provide a heat-sensitive recording material having an excellent head matching performance and a surface which is coated well without any coating defects. Another object of the present invention is to provide a method for producing such a heat-sensitive recording material.
As a result of diligent studies on lubricants contained in protective layers by the present inventors trying to improve head matching performance and to eliminate coating defects, it was found that an emulsion of silicone oil dispersed so as to have a specific particle diameter or less has excellent head matching performance, a good stability against external stimuli such as mechanical shear or ultrasonic waves, and an extremely low incidence of coating defects. The present invention has been completed on the basis of these findings.
The present invention provides a heat-sensitive recording material comprising a substrate, and a heat-sensitive recording layer and a protective layer disposed on the substrate in that order, wherein the protective layer is formed by applying a coating solution for the protective layer containing a pigment, a binder, and an emulsion of silicone oil, wherein the silicone oil is dispersed so that an average particle diameter of the silicone oil is 0.15 &mgr;m or less.
In another aspect, the present invention provides a heat-sensitive recording material, wherein the silicone oil satisfies a relational expression d2/d1≦1.5, where d1 is the average particle diameter of the silicone oil in the emulsion and d2 is the average particle diameter of the silicone oil after the emulsion of the silicone oil is diluted 50 fold with water.
In still another aspect, the present invention provides a heat-sensitive recording material, wherein the silicone oil satisfies a relational expression d3/d1≦1.5, where d1 is the average particle diameter of the silicone oil in the emulsion and d3 is the average particle diameter of the silicone oil after the emulsion of the silicone oil is diluted 50 fold with water and then irradiated by ultrasonic waves with an output power of 100 W at 40 Hz for 30 minutes.
In still another aspect, the present invention provides a heat-sensitive recording material, wherein the silicone oil satisfies a relational expression d4/d1≦1.5, where d1 is the average particle diameter of the silicone oil in the emulsion and d4 is the average particle diameter of the silicone oil after the emulsion of the silicone oil is diluted 50 fold with water and then stirred by a homogenizer at 5000 rpm for 10 minutes.
In still another aspect, the present invention provides a heat-sensitive recording material, wherein the silicone oil is at least one type of silicone oil selected from the group consisting of ether modified silicone oil, carboxy modified silicone oil and amino modified silicone oil.
In still another aspect, the present invention provides a heat-sensitive recording material, wherein the silicone oil has a viscosity within a range from 400 to 100,000 cps.
In still another aspect, the present invention provides a method for producing a heat-sensitive recording material including the steps of:
(a) forming a heat-sensitive recording layer on a substrate by applying a coating solution for forming the heat-sensitive recording layer; and
(b) forming a protective layer on the heat-sensitive recording layer by applying another coating solution for forming the protective layer containing at least a pigment and a binder,
wherein the coating solution for forming the protective layer contains an emulsion of silicone oil, wherein the
Fuji Photo Film Co. , Ltd.
Hess Bruce
Sughrue & Mion, PLLC
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