Stock material or miscellaneous articles – Ink jet stock for printing – Particles present in ink receptive layer
Reexamination Certificate
1997-08-25
2003-09-16
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Ink jet stock for printing
Particles present in ink receptive layer
C428S032100
Reexamination Certificate
active
06620469
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an ink jet recording sheet. More particularly, the present invention relates to an ink jet recording sheet which can be processed and recorded on to the same extent as conventional wood-free paper sheets and coated paper sheets, can record thereon colored ink images with excellent clarity and satisfactory dot quality, and has an excellent water resistance.
(2) Description of Related Art
Due to a significant development in the performance, for example, the printing speed and the resolving power, of ink jet type printers and the saturation of the recorded colored images, recording materials are required to have enhanced performances, for example, high ink absorption rate, high ink absorption capacity, regulated ink spreading property, etc., and thus various coated paper type ink jet recording sheets each having an ink receiving coating layer formed on a surface thereof have been developed.
For example, Japanese Unexamined Patent Publication No. 62-158,084 discloses an ink jet recording medium having an ink receiving layer containing fine synthetic silica particles and exhibiting high ink-absorbing property, color-reproducibility and color density. Namely, to satisfy the above-mentioned requirements, the ink jet recording sheet has a coating layer comprising, as a principal component, a white pigment such as the fine synthetic silica particles, having an excellent ink-absorbing property, and formed on a surface of a substrate comprising, as a principal component, cellulosic pulp.
Also, due to an expansion of use of ink jet printers, the use of the ink jet recording sheets has expanded from conventional documents, for example, office documents to colored advertising materials, particularly, advertising materials at the point of sale (POS advertising materials).
The ink jet recording system needs no printing plate and thus is definitely different from a printing system. Therefore, the ink jet recording system is advantageous in that a small amount of recording can be carried out and the cost is low.
The conventional ink jet recording sheets have a substrate sheet formed from a conventional cellulosic pulp, and thus are disadvantageous in that the recording sheets have a low water resistance and are easily damaged when wetted with water. Also, even when a water-resistance-enhancing treatment is applied to the substrate paper sheets, the resultant recording sheets are still unsatisfactory in resistances to elongating, wrinkling and curling phenomena. Namely, the conventional ink jet recording sheets are unsatisfactory in the water resistance thereof.
Japanese Unexamined Patent Publication No. 64-36,478 discloses an ink jet recording sheet comprising a substrate formed from a film comprising, as a principal component, a polyolefin resin, and a hydrophobic ink-absorbing and fixing layer formed on the substrate, and exhibiting an excellent water resistance. This type of ink jet recording sheet has an excellent water resistance and is usable for POS advertisements.
This type of ink jet recording sheet is usable only for ink jet printers using an oily ink. Namely, the above-mentioned ink jet recording sheet is not usable for ink jet printers using an aqueous ink. Also, the hydrophobic ink-absorbing and fixing layer does not always exhibit a high water resistance.
Also, even when the water-resistant film comprising, as a principal component, a polyolefin resin is used as a substrate sheet, when a conventional ink receiving layer is formed on the substrate sheet, and wetted with water droplets and rubbed with a finger or a pen, the ink receiving layer is easily peeled off at the interface between the ink receiving layer and the substrate sheet, due to a poor water resistance thereof. As mentioned above, an ink jet recording sheet having an aqueous ink-receiving layer with a satisfactory water resistance has not yet been supplied.
Japanese Unexamined Patent Publication No. 1-225,585 and No. 5-051,470 discloses an ink jet recording sheet having an undercoat layer formed between a substrate sheet and an ink-receiving layer. The undercoat layer of the above-mentioned publications is an ink-holding layer or an ink-receiving layer which cannot enhance the water-resistance of the recording sheet.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an ink jet recording sheet capable of being recorded with aqueous ink images with high quality at a high speed by an ink jet recording printer and having an excellent water resistance.
The above-mentioned object can be attained by the ink jet recording sheet of the present invention, which comprises a substrate comprising a polymeric film or sheet; an ink receiving layer comprising a pigment and a polymeric binder; and an undercoat layer formed between the substrate and the ink receiving layer and comprising a polymeric binder having a glass transition temperature of 50° C. or less.
In the ink jet recording sheet of the present invention, the pigment for the ink receiving layer may comprise a plurality of fine amorphous silica particles.
In the ink jet recording sheet of the present invention, the undercoat layer may further comprise a pigment.
In this case, the pigment for the undercoat layer preferably has an oil absorption of 250 ml/100 g or less, determined in accordance with Japanese Industrial Standard K 5101.
In the ink jet recording sheet of the present invention, the polymeric binder for the undercoat layer preferably comprises a water-dispersible resin having a glass transition temperature of 50° C. or less.
Also, in the ink jet recording sheet of the present invention, the polymeric binder in the undercoat layer may be cross-linked with a cross-linking agent.
In the ink jet recording sheet of the present invention, the undercoat layer is preferably in an amount of 0.2 to 15.0 g/m
2
.
In the ink jet recording sheet of the present invention, the polymeric film for the substrate is preferably selected from biaxially oriented films.
In the ink jet recording sheet of the present invention, the polymeric binder of the undercoat layer preferably has a glass transition temperature of −30° to 50° C.
In the ink jet recording sheet of the present invention, the undercoat layer is preferably in an amount of 0.5 to 8.0 g/m
2
.
In the ink jet recording sheet of the present invention, the cross-linking agent for the undercoat layer preferably comprises at least one isocyanate compound.
In the ink jet recording sheet of the present invention, the undercoat layer preferably exhibits a water repellency of R6 or more determined in accordance with Japanese Industrial Standard P 8137.
In the ink jet recording sheet of the present invention, the polymeric film or sheet for the substrate is preferably selected from biaxially oriented films comprising an inorganic pigment and a thermoplastic resin.
In the ink jet recording sheet of the present invention, the polymeric binder contained in the undercoat layer and having a glass transition temperature of 50° C. or less, may be derived from an aqueous acrylic resin emulsion.
Further, in the ink jet recording sheet of the present invention, the undercoat layer preferably comprises pigment particles, more preferably inorganic pigment particles, having an aspect ratio, which is a ratio of major axis length to minor axis length of the particles, of 2.0 to 100.0.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The ink jet recording sheet of the present invention comprises a substrate formed from a polymeric film or sheet, an undercoat layer formed on a surface of the substrate and comprising a polymeric binder having a glass transition temperature of 50° C. or less and an ink receiving layer formed on the undercoat layer and comprising fine amorphous silica particles and a hydrophilic polymeric binder.
The ink jet recording sheet of the present invention is characterized by the specific undercoat layer formed between the substrate and the ink receiving layer.
In a conventional ink jet recording sheet wherein an ink re
Ohshima Kazuaki
Sugiyama Naonobu
Totani Kazuo
Arent Fox Kintner & Plotkin & Kahn, PLLC
Grendzynski Michael E.
Hess Bruce H.
Oji Paper Co. Ltd.
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