Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
2000-07-10
2002-08-13
Cain, Edward J. (Department: 1714)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
Reexamination Certificate
active
06432550
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an ink-jet recording sheet, particularly relates to paper for ink-jet printing capable of recording a character or a color image each having a high image quality on both of the sides thereof.
BACKGROUND OF THE INVENTION
Recently, the quality of image printed by an ink-jet printer is becomes to be equal to that of the image obtained by the silver halide photography accompanied with a rapid progress of the ink-jet recording technology.
Various kinds of color prints can be made by the ink-jet printer-accompanied with the spreading of ink-jet printers and digital cameras, and the use of the print printed by the ink-jet printer is diversified recently.
One of such the uses of the print is ink-jet recorded images formed on the both sides of recording sheet. The recording sheet capable of recording images on the both sides thereof is suitable to reduce the number of paper sheet for resource saving and to prepare a new color print to be made in a booklet form or a various types of cards such as a post card.
Some recording sheet having ink-jet recording layers on the both sides thereof have been proposed.
Japanese Patent Publication Open to Public Inspection (hereinafter referred to JP O.P.I.) No. 56-148584 discloses a method for preventing the stain on the back surface by using recording sheet having layer containing porous inorganic pigment particles on the both sides thereof to inhibit the penetration of the ink to the opposite side of the paper.
JP O.P.I. No. 2-270588 discloses ink-jet recording sheet excellent in the feeling of paper quality and prevented in the penetration of ink to the back side, in which ink absorption layers are provided on the both sides of the paper and the ink absorption layer is made thin for preventing the peeling off of the ink absorption layer.
JP O.P.I. No. 8-174996 discloses that ink-jet recording sheet can be obtained by providing an ink absorption layer mainly composed of an inorganic pigment and a binder on one side of the base paper and immersion or coating a cationic substance to the other side of the paper. On this paper, a clear image can be recorded on one side and an ink-jet record and a writing by various kinds of writing materials can be made on the other side, and the penetration of the ink to the opposite side of the paper is prevented. Such the recording sheet is mainly used as a card or a post card.
JP O.P.I. No. 9-286116 describes ink-jet recording sheet having ink absorption layer on the both sides of a substrate different from each other in the dot diameter formed when an ink droplet is adhered thereon. Ink-jet recording sheet without curling or ink penetration to the back surface can be obtained by such the methods.
SUMMARY OF THE INVENTION
Ink-jet recording sheet capable of forming high quality images on the both sides thereof has been investigated by the inventors. As a result of that, it has been found that the image formed on one side of the paper is transparently looked on the back side through the paper, or paper through image visibility, cannot always be sufficiently inhibited even when the dye fixing ability of the ink absorption layer is increased.
The paper through image visibility tends to be occurred when a black image, a character or picture, is printed on one side and no or low density image is printed on the other side of the paper.
The paper through image visibility cannot be sufficiently inhibited even when the image is recorded by a pigment ink and colored pigment particles are substantially fixed on the surface of the ink absorption layer and almost particles of the pigment are not penetrated into the ink absorption layer.
The paper through image visibility can be improved some degree by raising the opacity of the ink absorption layer by the addition of a coarse pigment particle or the use of an inorganic pigment having a high refractive index. In such the case, however, the density of the image printed by the ink-jet is considerably lowered and the paper through image visibility cannot be controlled only by the increasing of the dye fixing ability and the opacity of the ink absorption layer.
It has been found by the inventors that the paper through image visibility can be reduced without loss of the image density by improving both of the support and the ink absorption layer.
The object of the invention is to provide an ink-jet recording sheet in which the lowering of image density is small and the image is difficultly seen through the paper when images are printed on the other side of the paper by ink-jet printing.
The invention and the embodiments thereof are described below.
Ink-jet recording sheet comprising a support having an opacity of not less than 94% according to JIS P 8138 and ink absorption layers each containing a cationic substance and provided on the both sides of the support.
Ink-jet recording sheet comprising a support having a Kobb Test permeability of not more than 10 g per square meter determined according to JIS P 8140 using pure water containing 30% by weight of diethylene glycol for a contacting time of 10 seconds and a opacity of not less than 94% according to JIS P 8138, and ink absorption layers each containing a cationic substance and provided on the both sides of the support.
The support is preferably a hydrophobic support.
The support is preferably a support comprised of a paper substrate covered with polyolefin resin layers on the both sides thereof, and at least one of the olefin resin layers contains a white pigment.
Each of the ink absorption layers provided on both sides of the support preferably includes at least one porous layer.
The ratio of D1/D2 is preferably within the range of from 0.90 to 1.1 wherein D1 and D2 are each the diameter of dot formed by a droplet of ink adhered on the ink absorption layer provided on one side of the support and that of the dot formed on ink absorption layer provided on the other side of the support, respectively.
Ink-jet recording sheet comprising a plastic film support containing a white pigment and having a opacity according to JIS P 8138 of not less than 94% and ink absorption layers containing a cationic substance each provided on the both sides of the support.
Ink-jet recording sheet comprising a support comprised of paper support having a weight of from 100 g to 250 g per square meter covered with a polyolefin resin containing a white pigment, which has an opacity according to JIS P 8138 of not less than 94%, and ink absorption layers each containing a cationic substance and provided on the both sides of the support.
The cationic substance is preferably a compound having a quaternary ammonium salt group.
DETAILED DESCRIPTION OF THE INVENTION
The support of the ink-jet recording sheet of the invention has an opacity according to JIS P 8138 of not less than 94%.
When the opacity is less than 94%, the image tends to be seen through the paper when the recording sheet is observed from the opposite side. The opacity of the support is preferably not less than 95%, particularly not less than 96%.
Paper, white plastic film, clothes, and paper laminate with plastic resin on one or both sides thereof are usable as the support having an opacity of not less than 94%.
The opacity of paper support of not less than 94% can be attained by increasing the weight of the paper or addition of white a pigment into the paper. The weight of paper is usually from 100 g to 300 g per square meter even though the weight may changed depending on the presence of the white pigment. The weight is usually from 150 g to 300 g, preferably from 200 g to 300 g, more preferably from 220 g to 300 g, when no white pigment is used.
When the white pigment is used, the weight is usually from 100 g to 250 g, preferably from 150 g to 200 g, even though the weight is considerably changed depending on the amount of the white pigment.
Titanium oxide, barium sulfate, zinc oxide, silica and calcium carbonate are usable as the white pigment to be used in the paper. Examples of preferable hydrophobic support include a plastic film and a paper
Ebisawa Harue
Ohbayashi Keiji
Bierman, Muserlian and Lucas
Cain Edward J.
Konica Corporation
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