Stock material or miscellaneous articles – Surface property or characteristic of web – sheet or block
Patent
1990-01-11
1991-10-29
Ryan, Patrick J.
Stock material or miscellaneous articles
Surface property or characteristic of web, sheet or block
428195, 428480, 4284231, 101127, 10112821, 1011284, B32B 900
Patent
active
050615653
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a film for heat-sensitive mimeograph stencil which may be processed by flash irradiation with a xenon flash lamp and the like, or by a thermal head. This invention also relates to a heat-sensitive mimeograph stencil employing the film.
BACKGROUND ART
Conventional heat-sensitive mimeograph stencils typically comprise a film for heat-sensitive mimeograph stencil and a porous support adhered to the film with an adhesive. Conventional films for heat-sensitive mimeograph stencils include vinyl chloride-vinylidene chloride copolymer film, polypropylene film and polyethyleneterephthalate film, and conventional porous supports include tissue paper and polyester gauze.
However, if the film for heat-sensitive mimeograph stencil is made of a vinyl chloride film, vinylidene chloride copolymer film or a polypropylene film as disclosed in, for example, Japanese Patent Disclosure (Kokai) No. 48395/85, the film does not have sufficient stiffness and its slipperiness is bad, so that a thick film has to be used. Further, since the energy of crystal fusion .DELTA.Hu of the resin is great, the heat-sensitivity is low. As a result, characters and paint-printed symbols or figures (symbols or figures such as and in which ink is applied in a large area) cannot be printed clearly. On the other hand, if the film for heat-sensitive mimeograph stencil is made of a polyethyleneterephthalate film as disclosed in, for example, Japanese Patent Disclosure (Kokai) Nos. 85996/85 and 16786/84, the film has sufficient stiffness and the slipperiness is relatively good. However, since its .DELTA.Hu is great, to promote heat-sensitivity the thickness of the film must be made considerably small. As a result, the film tends to be broken easily and to be wrinkled during the film forming process, so that the production yield may be largely reduced. In either case, the shades of the printed characters, and the thicknesses of the printed characters are uneven, and the thin black characters cannot be printed due to the low sensitivity.
DISCLOSURE OF THE INVENTION
Accordingly, the object of the present invention is to provide a film for a heat-sensitive mimeograph stencil with a high heat-sensitivity by which characters and paint-printed symbols and figures may be clearly printed, the characters being free from unevenness of thickness and from light and shade, which film excels in durability and ease of handling, and which film offers high production yield.
Another object of the present invention is to provide a heat-sensitive mimeograph stencil employing the above-described film for heat-sensitive mimeograph stencils of the present invention.
The film for heat-sensitive mimeograph stencils of the present invention is made of a biaxially stretched polyester-based film having an energy of crystal fusion .DELTA.Hu of 3-11 cal/g and a difference .DELTA.Tm between the crystal fusion-terminating temperature and the crystal fusion-starting temperature of 50.degree. C. to 100.degree. C.
The film for heat-sensitive mimeograph stencils of the present invention has high heat-sensitivity, so that the printed characters and the paint-printed symbols and figures are clear and substantially free from unevenness in thickness and from light and shade. Further, since it is not necessary to make the film very thin, breaking and wrinkling of the film in the production process are unlikely to occur, so that the production yield of the film is high. Moreover, the film has excellent durability, so that the ease of handling of the film is excellent.
BEST MODE FOR CARRYING OUT THE INVENTION
The term "heat-sensitive mimeograph stencil" herein mean those which may be processed by the well-known method disclosed, e.g., in Japanese Patent Publication (Kokoku) No. 7623/66 using flash irradiation with a xenon lamp or using a thermal head, and which comprises a film for forming a heat-sensitive mimeograph stencil (hereinafter referred to as "heat-sensitive film" for short) and a porous support to which the heat-sensitive film is adh
REFERENCES:
patent: 4766033 (1988-08-01), Yoshimura et al.
patent: 4961377 (1990-10-01), Bando et al.
Aoki Seizo
Mimura Takashi
Nakahara Yasuji
Sumiya Takashi
Tsunashima Kenji
Miller Austin R.
Ryan Patrick J.
Toray Industries Inc.
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