Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or...
Reexamination Certificate
2001-03-02
2003-07-22
Hess, Bruce H. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
C428S304400
Reexamination Certificate
active
06596668
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat-sensitive recording material which has an excellent resolution and can provide a vivid recorded image in a high density and which brings about less inferior appearance such as curling and irregularities after recording.
2. Description of the Related Art
In general, known is a heat-sensitive recording material prepared by providing a heat-sensitive color developing layer on a support such as paper, synthetic paper or a plastic film. Contained in the heat-sensitive color-developing layer are a colorless or light-colored developing material, a developer, a binder, a filler, a sensitizer, a lubricant and other auxiliary agents, and a color-developed image is obtained by momentary chemical reaction caused by heating by means of a hot pen or a thermal head.
A recording apparatus for such heat-sensitive recording material is inexpensive and small-sized, and maintenance thereof is easy, so that it is widely used as a recording medium in printers for a facsimile, various calculators, medical instruments, an automatic ticket distributor, a heating copying machine and other various apparatuses.
In particular, a heat-sensitive recording material comprising a support of synthetic paper or a plastic film is used when a water resistance and a strength are required or an image printer in which a uniformity and a high resolution are required to a recorded image is used.
Most synthetic papers and plastic films used as a support for a heat-sensitive recording material are produced by using a polyolefin resin or a polyester resin as a base, blending it with a white inorganic pigment and stretching it in machine direction and in transverse direction in order to provide it with a whiteness and a cushioning property.
Among them, in the case of a heat-sensitive recording material using a polyolefin resin as a base for a support, there has been the problem that recording in a high density by means of a thermal head results in allowing the support to shrink due to transmission of heat to bring about inferior appearance such as curling and irregularities. In order to solve these problems, a method in which a support is subjected to heat treatment in a rolling state is proposed, but it is not necessarily satisfactory. On the other hand, in the case of a heat-sensitive recording material using a polyester base resin as a base for a support, curling and irregularities are not caused, but the cost grows high. Accordingly, desired is a heat-sensitive recording material in which an inexpensive polyolefin base resin is used for a base and which brings about less inferior appearance such as curling and irregularities.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a heat-sensitive recording material which uses a polyolefin resin as a base for a support but brings about less inferior appearance such as curling and irregularities and which has an excellent resolution and can provide a vivid recorded image in a high density.
Intensive researches repeated by the present inventors have resulted in finding that the object described above can be achieved by a heat-sensitive recording material in which used as a support is a void-containing stretched film comprising a crystalline polypropylene resin and a dicyclopentadiene petroleum resin as essential components and in which a heat-sensitive recording layer is formed on a surface thereof, and thus they have completed the present invention.
The present invention comprises the following structures.
(1) A heat-sensitive recording material comprising a void-containing stretched film comprising a crystalline polypropylene resin and a dicyclopentadiene petroleum resin as essential components and a heat-sensitive recording layer formed on a surface thereof
(2) The heat-sensitive recording material as described in the above item (1), wherein the void-containing stretched film comprising a crystalline polypropylene resin and a dicyclopentadiene petroleum resin as essential components is a void-containing laminated stretched film obtained by laminating a surface layer film comprising a composition of the crystalline polypropylene resin on both faces of a base layer film comprising a composition prepared by blending 5 to 180 parts by weight of a dicyclopentadiene petroleum resin having a softening point (ring and ball method) of 160 to 200° C. with 100 parts by weight of the crystalline polypropylene resin and then stretching it at an area magnification of 5 times or more.
(3) The heat-sensitive recording material as described in the above item (1), wherein the void-containing stretched film comprising a crystalline polypropylene resin and a dicyclopentadiene petroleum resin as essential components is a compression-treated void-containing laminated stretched film obtained by hot-compressing the void-containing stretched film as described in the above item (2) at a temperature of 50 to 160° C. and a pressure at which the void-containing laminated stretched film described above does not become transparent.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The embodiment of the present invention shall be explained below.
In the heat-sensitive recording material of the present invention, the void-containing stretched film which is the support is a void (fine void)-containing single layer stretched film or a void-containing laminated stretched film obtained by stretching at an area magnification of 5 times or more, a single layer non-stretched film sheet obtained from a resin composition (hereinafter referred to as a resin composition for a void-containing stretched film) comprising a crystalline polypropylene resin and a dicyclopentadiene petroleum resin as essential components or a laminated non-stretched film sheet which comprises the single layer non-stretched film sheet described above as a base layer and in which a surface layer film comprising a composition of the crystalline polypropylene resin is laminated on at least one face of the base layer.
The crystalline polypropylene resin used for the resin composition for the void-containing stretched film described above or the composition (hereinafter referred to as the resin composition for the surface layer film) of the crystalline polypropylene resin for the surface layer film described above is a crystalline homopolymer of propylene, a binary or higher copolymer of propylene with at east one selected from ethylene and &agr;-olefin having 4 or more carbon atoms or a mixture thereof. To be specific, it includes propylene base polymers having a crystal melting point such as crystalline polypropylene containing a boiling heptane-insoluble part of 70% or more, preferably 80% or more, and crystalline propylene copolymers containing a propylene component of 70% or more, such as a crystalline ethylene·propylene copolymer, a crystalline propylene·1-butene copolymer, a crystalline propylene·1-hexene copolymer and a crystalline ethylene·propylene·1-butene copolymer.
The crystalline polypropylene resins used for the resin composition for the void-containing stretched film and the resin composition for the surface layer film may be the same or different.
The crystalline polypropylene resin has a melt flow rate (measured on a condition 14 (test temperature: 230° C. and test load: 21.18 N) shown in Table 1 of JIS K-7210 ┌Flow test method of thermoplastic plastics┘, hereinafter referred as MFR) of 0.5 to 20 g/10 minutes, preferably 0.5 to 10 g/10 minutes.
The dicyclopentadiene petroleum resin used for the resin composition for the void-containing stretched film described above has preferably a softening point (ring and ball method) of 160 to 200° C.
If the dicyclopentadiene petroleum resin has a softening point (ring and ball method) of lower than 160° C., the void-containing single layer stretched film is not obtained by stretching the single layer non-stretched film or sheet obtained from the resin composition for the void-containing stretched film. On the other hand, if it exceeds 200° C., the dispersibility
Hattori Takahiro
Kuroda Takashi
Yamada Kazuhiro
Chisso Corporation
Hess Bruce H.
Wenderoth , Lind & Ponack, L.L.P.
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