Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2000-04-07
2002-08-13
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S219000, C428S213000, C428S340000
Reexamination Certificate
active
06432519
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording sheet and, in more detail, to an ink jet recording sheet which results in fewer cracks, and exhibits excellent coated film strength as well as excellent gloss.
Ink jet recording systems produce little noise, and are capable of carrying out high-speed recording as well as multicolor imaging. Accordingly, they are employed in many fields, such as various types of printers, plotters, and the like.
An ink jet recording sheet is commonly constituted in such a manner that an ink absorptive layer (absorbing layer) is applied via a sublayer (subbing layer) onto a support, utilizing various types of paper such as wood-free paper, coated paper, and the like, synthetic paper, plastic films, and the like.
Most of the ink absorptive layers are comprised of fine solid particles in order to enhance ink absorbability by increasing the void ratio and to simultaneously provide sufficient ink fixability. The ink absorptive layer is commonly comprised of polymeric compounds as the binder, into which said fine solid particles are mixed and evenly dispersed. In order to uniformly coat such dispersion, as well as to enhance adhesion of the ink absorptive layer with the aforementioned support, a sublayer is commonly applied onto the support and thereon the ink absorptive layer is applied.
For the purpose of improving adhesion, as well as for carrying out uniform coating, frequently employed as such sublayers have been those comprised of water-soluble polymers. Such water-soluble polymers are employed to assure affinity with water-soluble polymers which are frequently employed as binders in the ink absorptive layer. Of these, gelatin is often employed to prepare the sublayer. However, a sublayer comprised of gelatin is not capable of sufficiently relaxing the contraction force which is generated in the interface between the sublayer and the ink absorptive layer during drying of the ink absorptive layer. As a result, problems occur in which the ink absorptive layer peels from the support, resulting in cracks.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to obtain an ink jet recording sheet which results in a decrease in minute cracks during drying, and exhibits excellent coated film strength as well as excellent gloss.
The object of the present invention can be achieved by the following structures or methods:
(1-1) An ink jet recording medium, comprises:
a support;
a first layer provided on the support; and
a second layer provided on the first layer so as to come in contact with the first layer, the second layer being an ink absorbing layer,
wherein an elastic modulus of the first layer is smaller than a Young's modulus of the second layer.
(1-2) In the ink jet recording medium of (1-1), the first layer is a subbing layer.
(1-3) In the ink jet recording medium of (1-1), the second layer comprises a void structure.
(1-4) In the ink jet recording medium of (1-1), the first layer comprises an organic polymer and the second layer contains the same organic polymer as that of the first layer.
(1-5) In the ink jet recording medium of (1-1), the first layer contains polyvinyl alcohol.
(1-6) In the ink jet recording medium of (1-1), a coating weight of the first layer is 0.03 g/m
2
to 0.4 g/m
2
.
(1-7) In the ink jet recording medium of (1-1), a thickness of the second layer is 5 &mgr;m to 50 &mgr;m.
(1-8) In the ink jet recording medium of (1-1), a thickness of the first layer is 0.03 &mgr;m to 0.4 &mgr;m.
(1-9) In the ink jet recording medium of (1-1), a thickness of the second layer is larger 10 times or more than that of the first layer.
(1-10) A method of manufacturing an ink jet recording medium, comprises:
a step of providing a second layer on a first layer provided on a support, wherein the second layer is an ink absorbing layer and has a Young's modulus larger that that of the first layer.
(1-11) In the method of (1-10), the step of providing the second layer comprises a step of coating a coating solution on the first layer and a step of drying the coating solution so as to obtain the second layer.
(1-12) In the method of (1-10), the method further comprises a step of providing the first layer before the step of providing the second step.
(1-13) In the method of (1-10), the first layer is a subbing layer.
(1-14) In the method of (1-10), the second layer is provided by simultaneously coating with the firs layer so as to form a multi layer.
(1-15) In the method of (1-10), the simultaneously coating is conducted with a curtain coater.
(1-16) In the method of (1-10), the simultaneously coating is conducted with a slide coater.
Further, the object of the present invention may be achieved by the preferable means or methods described below:
(2-1) In an ink jet recording sheet comprising a support having thereon a sublayer and thereon an ink absorptive layer in contact with said sublayer, an ink jet recording sheet characterized in that the Young's modulus of said sublayer is less than said ink absorptive layer.
(2-2) The ink jet recording sheet described in (2-1), characterized in that said sublayer is comprised of polyvinyl alcohol.
(2-3) The ink jet recording sheet described in (2-1) or (2-2),
wherein the weight of said coated sublayer is between 0.03
and 0.4 g/m
2
.
(2-4) A coating method of an ink jet recording sheet characterized in that the sublayer and the ink absorptive layer of the ink jet recording sheet, described in 1., 2., or 3. above, are simultaneously coated as multiple layers.
(2-5) The coating method of the ink jet recording sheet described in (2-4), characterized in employing a curtain coater.
(2-6) The coating method of an ink jet recording sheet described in (2-4), characterized in employing a slide coater.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will now be detailed below.
In view of the foregoing, the present inventors have diligently investigated and have accomplished the present invention. Namely, it has been discovered that minute cracks formed during drying are due to stress generated in the interface between the ink absorptive layer and the sublayer during drying, and the relaxation of said stress markedly decreases cracks. According to the present invention, said stress generated in the interface between said sublayer and said ink absorptive layer is effectively relaxed by employing a sublayer having a lower Young's modulus. Further, when setting a lower Young's modulus in the sublayer compared to the ink absorptive layer, the desired effects are exhibited. Accordingly, still more preferable effects are exhibited by replacing gelatin in the sublayer with, for example, polyvinyl alcohol, having a lower Young's modulus than gelatin.
The Young's modulus of each layer is measured as follows. Each coating solution is applied onto the surface of a polypropylene plate and subsequently dried. The coated layer is then peeled off and a 200 &mgr;m thick layer is prepared. The Young's modulus of the resulting layer is measured in a room conditioned at 25° C. and 60% RH.
The Young's modulus of the ink absorptive layer is preferably adjusted to the range of 50 to 100 kg/mm
2
, while that of the sublayer is preferably adjusted to the range of 20 to 100 kg/mm
2
, which is less than the ink absorptive layer.
By so doing, an ink jet recording sheet is obtained which results in a decrease in cracks and exhibits excellent coated film strength, as well as excellent gloss.
In order to adjust the Young's modulus of the sublayer to be lower than the ink absorptive layer, materials may be selected and combined so that such relationship as described above is obtained. Further, coating solutions may be prepared by incorporating into each coating solution materials which control the Young's modulus. The materials, which control the Young's modulus, may be incorporated into either the ink absorptive layer or the sublayer. However, they are preferably incorporated into the sublayer so that a decrease in ink
Kazama Kenichi
Maehara Yuichiro
Bierman, Muserlian and Lucas
Hess Bruce H.
Konica Corporation
Shewareged B.
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