Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2001-03-29
2004-06-22
Shosho, Callie (Department: 1714)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C524S517000, C524S521000, C524S523000, C525S187000
Reexamination Certificate
active
06753069
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a resin composition for an ink jet recording sheet, an ink jet recording sheet, a method for ink jet recording, and a method for producing an ink jet recording sheet. More particularly, the present invention relates to a resin composition that is suitable for ink jet recording in which a water-based ink is used, such an ink jet recording sheet, a method for ink jet recording in which a water-based ink is used, and a method for producing such an ink jet recording sheet.
BACKGROUND OF THE INVENTION
Ink jet recording is quiet, allows for high-speed printing, makes multicolored printing possible by using a plurality of nozzles, and is low in cost. Therefore, its use rapidly became wide-spread as output devices for image information, such as color copying, computers, and the like. Media for this ink jet recording require properties as follows:
(1) absorption velocity of ink is rapid;
(2) ink can be immediately evaporated to dryness;
(3) diffusion upon absorption of ink, and formation of unclear marginal portions of dots, are avoided;
(4) incidence rates of lack in printing uniformity is low;
(5) clear interfaces between different color zones can be provided; and
(6) quality stability is maintained over the long-term preservation after printing, particularly a low incidence of inferior alteration of images, such as blurring even under humid conditions, is provided.
Conventionally, an ink jet recording sheet has been utilized which comprises a water insoluble film as a support and hydrophilic polymer as a major component of an ink absorption layer that is over-laid on the support. The hydrophilic polymer may include water soluble polymers, e.g., polyvinyl alcohol, denaturated polyvinyl alcohol, polyvinyl pyrrolidone, gelatin, and the like. Further, ink jet recording sheets comprising combinations of the above-described hydrophilic polymer and a water-absorbing resin, and combinations with porous inorganic powder, such as silica, alumina, and the like, also have been proposed. However, problems are suggested in that the water soluble resin overlaid as an ink absorption layer absorbs water during storage, thus blurring of ink results when recording is carried out using these ink jet recording sheets.
In order to overcome such disadvantages, an ink jet recording sheet is proposed that contains a cationic substance in the ink absorption layer, which would prevent blurring of ink through reactions between the cationic substance and anionic dyes that are used in the water-based ink. However, this type of ink jet recording sheet may lead to bleed out of the cationic substance on the surface of an ink-receiving layer due to an inferior mutual solubility between the cationic substance and the water soluble polymer. In addition, because such cationic substances have no thermoplasticity, manufacturing restrictions also may result, namely coating application with a solution must be conducted to produce the ink jet recording sheet. Moreover, the fixative property of reaction products between the cationic substance and anionic dyes that are ingredients of ink may be insufficient. Consequently, prevention of blurring phenomenon may sometimes be impossible. Additionally, alteration of color tone may be developed from reaction products of the cationic substance and anionic dyes.
As explained heretofore, an ink jet recording sheet that satisfies all of the various desired properties has not yet been accomplished. The present invention was achieved taking these problems into account, and is directed to providing a resin composition for an ink jet recording sheet, an ink jet recording sheet, a method for ink jet recording, and a method for producing an ink jet recording sheet, which can be satisfactory in various desired properties, particularly an ink absorption ability and a blurring suppressive effect.
SUMMARY OF THE INVENTION
The present invention that accomplishes the objects set forth above is directed to a resin composition for ink jet recording which comprises (1) a major component of a water-absorbing polymer compound represented by the formula (I) below, and (2) a cationic polymer compound.
In formula (I), “A” consists of:
with a manner of linkage therebetween being:
wherein m, n, and p represent integer numbers greater than or equal to 1. Additionally, a weight ratio that is calculated on the basis of each of the recurrence numbers m, n, and p is predetermined to be 44 ×(m +p)/(the molecular weight of the unit of the alkylene oxide having more than or equal to four carbon atoms)×n=94/6-80/20, while the weight ratio that is calculated on the basis of each of the recurrence numbers m and p, p/(m+p) should be predetermined to be more than or equal to 50 percent by weight. Y represents hydrocarbon group having more than or equal to two carbon atoms. Further, X
1
represents a residue of an organic compound having two active hydrogen groups, and R1 represents a residue of a dicarboxylic acid compound.
The resin composition for an ink jet recording sheet of the present invention comprises (1) a major component of a water-absorbing polymer compound represented by the formula (I) above and (2) a cationic polymer compound that is mutually solubilized with the compound (1), accordingly, blurring upon storage under humid conditions can be suppressed while an excellent ink absorption ability is retained.
In this aspect of the present invention, when the following compound (a) or (b) is used alone or in combination as the cationic polymer compound (2), bleed out on a surface of the ink-receiving layer is avoided due to their affinity to the water-absorbing polymer compound (I). In addition, alteration of color tone resulting from reactions with the anionic dyes that are used as ingredients of ink are prevented.
(a) A cationic polymer compound having a weight average molecular weight ranging between 1,000 and 50,000 with linear and irregular arrangement comprising 65 mol % to 99 mol % of an ethylene structural unit represented by the following formula (II), less than or equal to 15 mol % of an acrylate structural unit represented by the following formula (III), and 1 mol % to 35 mol % of an acrylamide structural unit represented by the following formula (IV):
wherein R
2
represents an alkyl group having 1-4 carbon atoms,
wherein R
3
represents an alkylene group having 2-8 carbon atoms; R
4
and R
5
respectively represent an alkyl group having 1-4 carbon atoms; R
6
represents an alkyl group having 1-12 carbon atoms, an aryl alkyl group having 7-12 carbon atoms, or an alicyclic alkyl group having 6-12 carbon atoms; and X
−
represents a halogen ion, CH
3
OSO
3
−
, or C
2
H
5
OSO
3
−
.
(b) A cationic polymer compound having a weight average molecular weight ranging between 1,000 and 50,000 with linear and irregular arrangement comprising 65 mol % to 99 mol % of an ethylene structural unit represented by the above formula (II), less than or equal to 15 mol % of an acrylate structural unit represented by the above formula (III), and 1 mol % to 35 mol % of an acrylamide structural unit represented by the following formula (V):
wherein R
3
represents an alkylene group having 2-8 carbon atoms; R
4
and R
5
respectively represent an alkyl group having 1-4 carbon atoms; and X
−
represents a halogen ion, CH
3
OSO
3
−
, or C
2
H
5
OSO
3
−
.
The cationic polymer compound (2) of the above-described (a) and (b) preferably comprises the acrylate structural unit represented by the formula (III), although the acrylate structural unit is not a necessary component to be contained therein. Therefore, the mole fraction of this acrylate structural unit is defined only in terms of an upper limit (15 mol %), and a lower limit thereof is not particularly defined.
In the present invention set forth above, when a mixing ratio by weight of the water-absorbing polymer compound (1) and the cationic polymer compound (2) ranges between 50/50 and 99/1, a well-balanced ink absorption ability and blurring suppr
Matsuo Katsuaki
Tsubaki Takayuki
Dai-Ichi Kogyo Seiyaku Co. Ltd.
Marshall & Gerstein & Borun LLP
Shosho Callie
LandOfFree
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