Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Patent
1991-10-02
1993-12-14
Ryan, Patrick J.
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
428198, 428201, 428202, 428264, 428211, 4285375, 428511, 428913, B32B 300
Patent
active
052700992
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a stencil paper used for mimeograph and, more particularly, to a heat-sensitive or thermal mimeograph paper designed to be cut or perforated by thermal printing means making use of a heat emitter element like a thermal head.
BACKGROUND TECHNIQUE
So far, mimeograph has been widely used as an expeditious and inexpensive printing system. According to this system, a material comprising a suitable porous backing sheet such as paper and a thermoplastic resin film layer laminated on its surface is used as a heat-sensitive stencil paper. This stencil paper is cut by a thermal head or other means, and the thermoplastic resin film layer is then heated and melted to form an imagewise perforation pattern, through which printing ink is fed to make prints on the material to be printed.
In order to improve the setting properties of stencil paper used with such a thermal setting system as mentioned above, especially, the capability of stencil paper to be perforated - hereinafter simply referred to as perforability, the choice of material and the selection of a bonding agent used for laminating the thermoplastic resin film on the porous backing material present important conditions, because this system is unique. As set forth in JP-A-58(1983)-147396 and 62(1987)-264998 specifications, thermal stencil paper products have heretofore been known in the art, which are obtained by bonding together a porous backing material and a thermoplastic resin film through an adhesive layer having a network or fine regular pattern.
When the backing material and thermoplastic resin film are laminated together with such an adhesive layer having a network pattern as set forth in JP-A-58-147396 specification into stencil paper, a perforating problem arises depending upon the amount of the adhesive applied, causing the deterioration of the resulting image quality.
In the case of stencil paper including an adhesive layer having such a specific, regular pattern as disclosed in JP-A-62-264998, it is awkward in itself to form an adhesive layer having such a regular pattern. According to the inventor's finding, even when the given pattern has been formed, there are such problems as whitening and moire depending upon how much adhesive is applied and to what extent bonding takes place, which in turn occasion various problems in making printing of high resolving power.
Thus, it is a primary object of this invention to provide a thermal stencil paper which can be well cut or perforated and makes printing of high resolving power feasible.
Incidentally, thermal stencil paper used with the above-mentioned conventional, thermal mimeograph system is formed by laminated a thermoplastic resin film layer as thin as a few .mu.m in thickness on a porous backing material, generally paper, with the application of a bonding agent. This bonding agent is typically (1) a solvent (or aqueous) type of adhesive--see, e.g. JP-P-47(1972)-1188 and 1187 publications.
Problems with the solvent type of adhesive, which is used with large amounts of solvents, are that its recovery takes much cost, difficulty is involved in maintaining a working environment, the resulting products are poor in resistance to solvent, and the kind of ink used is limited.
Problems with the aqueous type of adhesive are that the quantity of heat needed for drying is enormous, and the thermoplastic resin film shrinks or the porous backing material suffers dimensional changes due to the heat applied during drying, making stencil paper curl or wrinkle.
(b) a solventless type of curing adhesives which are used for eliminating the above-mentioned defects of the solvent type of adhesives see JP-A-61(1986)-286131, 58(1983)-153697, 62(1987)-181374 and 63(1988)-233890 specifications.
Of these adhesives, the heat curing type of adhesive requires a large amount of heat for curing, and further offers problems that the thermoplastic resin film shrinks or the porous backing material undergo dimensional changes during the production of stencil paper, making the stencil pape
REFERENCES:
Patent Abstracts of Japan, vol. 10, No. 281 (M-250 [2337] Sep. 25, 1986.
Patent Abstracts of Japan, vol. 12, No. 142 (M-692) [2989] Apr. 30, 1988.
Patent Abstracts of Japan, vol. 12, No. 428 (M-762) [3275] Nov. 11, 1988.
Patent Abstracts of Japan, vol. 7, No. 269 (M-259) [1414] Nov. 30, 1983.
Patent Abstracts of Japan, vol. 7, No. 275 (M-261) [1420] Dec. 8, 1983.
Ando Masayuki
Hiroi Junichi
Kamiyama Hironori
Komatsubara Kazue
Kosaka Yozo
Dai Nippon Insatsu Kabushiki Kaisha
Evans Elizabeth
Ryan Patrick J.
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