JPH0939373A - Ink jet recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain ink jet recording paper suppressing the blur or expanse of dots and excellent in ink absorbability by coating base paper with an acrylamide copolymer modified polyvinyl alcohol resin. SOLUTION: A copolymer resin obtained by subjecting vinyl acetate and acrylanaide to soln. polymerization in methanol is saponified with caustic soda in methanol to obtain an acrylamide copolymer modified polyvinyl alcohol resin. Neutral paper is used as base paper and an aq. soln. consisting of about 2 pts.wt. of the modified resin and about 100 pts.wt. of water is applied to the rear surface of the base paper so that the coating amt. thereof becomes about 0.4g/m<2> . After the coated base material is dried in air, it is subjected to one-pass treatment by an iron press and conditioned in an atmosphere of about 20 deg.C and about 65% RH for about 24hr to obtain recording paper for evaluation. When four-color printing is applied to this recording paper by a printer and the image quality and ink absorbability of a recording surface are evaluated, the blur or expanse of dots is suppressed and excellent water absorbability is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording paper, and more particularly to a recording paper which suppresses bleeding and spreading of dots and is excellent in ink absorption.

[0002]

2. Description of the Related Art Ink jet recording systems are characterized by low noise during recording, easy colorization, and high-speed recording, and their application to facsimiles and various printers has advanced. Has been. However, with the improvement of the performance of the inkjet recording apparatus such as the speeding up of the inkjet recording and the increase in the number of colors, more advanced characteristics have been demanded for the recording paper. Specifically, first, the ink adhering to the paper surface is quickly absorbed inside the paper layer, second, there is little spread of ink dots and whisker-like bleeding, and thirdly, the ink. For example, the dot density is high. Generally, the greater the ink absorbency, the faster the spread speed of the ink dots. Therefore, the above first and second conditions have contradictory properties, and it is not possible to satisfy these two conditions. Difficult, but a way to solve it is desired.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet recording paper which suppresses bleeding and spreading of dots and has excellent ink absorbency.
As a result of various studies, the present inventors have found an ink jet recording paper in which a base paper is coated with an acrylamide copolymerization-modified polyvinyl alcohol-based resin, and completed the present invention.

[0004]

The present invention is an ink jet recording paper in which a base paper is coated with an acrylamide copolymer modified polyvinyl alcohol resin.

Hereinafter, the present invention will be described in detail. The base paper used in the present invention can be appropriately selected and used from known papers such as neutral paper mainly composed of wood pulp, which are usually used for inkjet recording papers. Is not particularly limited. The acrylamide copolymer-modified polyvinyl alcohol-based resin used in the present invention (hereinafter abbreviated as AA-modified PVA) is a resin obtained by copolymerizing vinyl acetate and acrylamide by a method such as solution polymerization, which is a medium in the presence of an alkali. It is usually obtained by a method such as partial or complete saponification.

AA-modified PVA is usually composed of acrylamide units,
It consists of vinyl alcohol units and vinyl acetate units,
The vinyl acetate units may be saponified and converted into vinyl alcohol units. The content ratio of the acrylamide unit in the AA-modified PVA is 1 to the total number of moles of the acrylamide unit, the vinyl alcohol unit and the vinyl acetate unit.
17 mol% is preferable and 2-7 mol% is especially preferable.
If it is less than 1 mol%, the effect is almost the same as that of unmodified, and if it exceeds 17 mol%, no further improvement of the effect is observed. In addition, the content ratio of the vinyl alcohol unit in the AA-modified PVA is preferably 58 mol% or more with respect to the above total number of moles in consideration of water solubility in use. Average molecular weight of AA-modified PVA used in the present invention (by GPC method)
Is not particularly limited, but is preferably 44000 or more in consideration of the surface strength of the coated paper.

When the solution containing the AA-modified PVA used in the present invention is applied, in addition to the above-mentioned AA-modified PVA, for example, starch and its derivatives, cellulose such as carboxymethyl cellulose and methyl cellulose are applied to the solution. Derivative,
It contains a resin such as polyvinylpyrrolidone or SBR latex, or, if desired, is mainly used as a filler for enhancing the ink absorbency, such as finely divided silicic acid, clay, talc, diatomaceous earth, calcium carbonate, titanium oxide, and satin. White, aluminum silicate, alumina, styrene-based plastic pigment, acrylic-based plastic pigment, urea resin-based pigment, etc. may be contained within a range in which the spread of ink dots and whisker-like bleeding are small. In addition, AA-modified PVA contains melamine resin, zirconium ammonium carbonate, polyamide resin, glyoxal, polyamide epichlorohydrin, styrene-dialkylamino (meth), mainly for enhancing the water resistance of the recording area, if desired. A water-proofing agent such as an acrylate-epichlorohydrin system may be contained within a range that does not impair ink absorbability.

In the present invention, the method of applying the aqueous solution containing the AA-modified PVA to the base paper is a known method, for example, using a device such as a size press, roll coater, blade coater, air knife coater, bar coater or the like. Although a method of coating on one side or both sides of paper is usually used, a method of impregnating the above aqueous solution may be used. The coated paper can be dried by, for example, hot air, infrared rays, or a method combining these. In the present invention, AA modification
The coating amount of PVA (weight increase after drying of the base paper produced by coating) is usually 0.1 to 10 g / m ² , and AA-modified PVA
The concentration in the coating liquid is arbitrarily selected according to the coating device, operating conditions, and the like.

[0009]

The present invention will be described below in more detail with reference to examples and comparative examples. In the following description, "%" and "parts" mean mol% and parts by weight, respectively, unless otherwise specified.

Example 1 A copolymer resin obtained by solution polymerization of vinyl acetate and acrylamide in methanol was saponified with caustic soda in methanol and AA-modified PVA-I (acrylamide unit 3.1).
Mol%, vinyl alcohol unit 95.0 mol%,
Number average molecular weight (solvent: 0.1 mol of Nacl aqueous solution, polyethylene glycol-based GPC method) 82000
Is obtained). Table 1 shows the evaluation results.

(1) Preparation test of recording paper for evaluation Neutral paper (basis weight 65 g / m ² ) was used as a base paper, and AA modified
An aqueous solution consisting of 2 parts by weight of PVA-I and 100 parts by weight of water was coated on both sides of the base paper so that the coating amount (weight increase after drying of the substrate caused by coating) was 0.4 g / m ^2. Was coated using a size press machine (manufactured by Kumagai Riki). After air-drying it, one-pass treatment with an iron press (140 ° C), 20
Humidity was adjusted for 24 hours in an atmosphere of ° C and 65% RH to obtain a recording sheet for evaluation.

(2) Evaluation test of evaluation recording sheet Using the above evaluation recording sheet, an EPS as a printer is used.
ON MJ-700V2C (MACH-JET method) was used to perform four-color color printing of red, yellow, blue, and black. Next, the image quality and ink absorbency of the recording surface were evaluated by the following methods. (B) Image quality Evaluation was made by visual observation using an optical microscope. ⊚: Very good (small dot spread and clear contour) ○: Good Δ: Slightly poor ×: Large dot spread and whisker-like bleeding (b) Ink absorption Immediately after recording, The recorded portion was rubbed once with a finger, and the degree of contamination of the recorded portion with the ink was evaluated. ⊚: Very good (no stain on recording area) ◯: Good Δ: Slightly inferior ×: Stains ink and stains recording area (c) Pen writing size test J. In accordance with TAPPI paper pulp test method No. 12, the following inks were prepared on recording paper for evaluation, and the pen writing size degree was evaluated. Blue ink (composition) C.I. I Direct Blue 86 2 parts Diethylene glycol 20 parts Polyethylene glycol # 200 10 parts Water 70 parts

Examples 2 to 3 and Comparative Examples 1 to 3 Example 1 except that the polyvinyl alcohol resin having the properties shown in Table 1 was used in place of the AA-modified PVA-I used in Example 1. Similarly, an evaluation recording sheet was obtained. Table 1 shows the evaluation results.

[0014]

[Table 1] (Note 1) Oxidized starch: Oji Ace A (manufactured by Oji Corn Starch) The coating amount is 1.4 g / m 2.

[0015]

As described above, according to the present invention, the base paper is
The inkjet recording paper coated with the acrylamide copolymer-modified polyvinyl alcohol-based resin can provide a recording paper that suppresses bleeding and spreading of dots and is excellent in ink absorbency.

Claims (1)

[Claims] 1. An inkjet recording paper, characterized in that a base paper is coated with an acrylamide copolymer modified polyvinyl alcohol resin.