JP3031235B2 - Inkjet recording sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink recording material, and more particularly to a recording sheet for an ink jet printer having excellent dimensional stability and improved appearance after printing.

[0002]

2. Description of the Related Art With the improvement of ink-jet type image recording apparatuses using water-based inks and inks, it has become possible to obtain clear images and prints using plain paper as the ink-jet paper. However, on the other hand, a recording material having higher characteristics has been required to make print quality, saturation, appearance, and image more attractive.

Conventionally, paper having excellent absorbency such as non-size paper has been used for its absorbency, or an absorbent coating layer such as silica has been provided on substantially non-size paper (Japanese Patent Publication No. 60-275).
No. 88), and a non-absorptive base material such as high-size paper or plastic film provided with an absorbent coating layer mainly composed of silica or the like (Japanese Patent Publication No. 63-65037). Improvements in absorption and color density have been observed.

[0004] In particular, ink-jet paper of a finely coated base paper absorption type is well-balanced in cost, feeling and performance, and is expected as a future ink-jet paper.

[0005] Ink-jet paper of the base paper absorption type has a good ink absorbency, and the ink is absorbed into the paper layer to become an apparently dry state. There are two things that need to be done. The two conditions are generally inconsistent and cause problems, as the more ink-absorbing paper, the more likely the resulting water-based ink will deform the paper. For example, if the absorption speed is increased by using low-size paper, the penetration of the ink becomes faster, and the ink penetrates deeply, causing curling and blurring.

On the other hand, if an absorbent coating layer is provided on a high-size base paper, the absorption speed of only the absorption layer can be increased, and the absorption of ink into the base paper can be suppressed. However, when the absorption limit of the ink of the absorbent coating layer is exceeded, bleeding or the like may be caused, and the risk of curling may increase, and the blur may not be completely eliminated.

JP-B-63-52588 proposes to reduce the fiber-to-fiber bond of a pulp by incorporating glass fiber and a large amount of a water-absorbing pigment, thereby reducing curling and unevenness. I have. In this case, the strength of the paper is lost, in addition to various problems in use due to the addition of the glass fiber, and there is a doubt about its practical use as a printer base paper.

Conventionally, paper having good dimensional stability has been known and used for OCR paper, NIP paper and the like. However, it reduces unevenness and curl due to water-based ink on paper,
The techniques and properties to be improved are not yet known. The base paper of the ink jet recording sheet of the present invention is mainly composed of cellulose pulp mainly made of wood, usually bleached kraft pulp, and if necessary, glass fiber, polyester fiber, polyvinyl alcohol fiber or other fiber. As long as it can be dispersed in water in the form, it can be used as a component.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a recording material for use in a multi-color or single-color ink jet printer using an aqueous ink, which has a high ink absorption speed, a large absorption capacity, and is irregular. It is an object of the present invention to provide an ink jet recording material capable of reducing curling and printing at a high speed and solving the above-mentioned disadvantages of the prior art.

[0010]

According to the present invention, 1 cm square C in a unit sheet is mainly composed of cellulose pulp.
On a papermaking sheet having a standard deviation of underwater elongation in the D direction of 30% or less of underwater elongation, ink receptivity mainly composed of a superabsorbent pigment containing fine-particle synthetic silica and a water-soluble polymer adhesive. An ink jet recording sheet comprising a coating layer provided at a rate of 0.5 to 15 g / m ² .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Ink-jet paper is usually A4
Although it is used in the form of cut sheets or fanfolds, it has been found that the unevenness due to the aqueous ink is caused by variations in the water elongation in these unit sheets. In particular, as a result of observing the cockling phenomenon caused by the aqueous ink on the high-quality paper made by the ordinary fourdrinier paper machine, the appearance of the paper is problematic. I understood. As a solution to such troubles caused by variations in the physical behavior of paper, it is important to manage the physical properties and the standard deviation of the behavior. The paper underwater Shin degree of the cellulose pulp as a raw material
There is a limit even if can be reduced to some extent.

Therefore, the sample sheet was cut into 1 cm squares close to the cycle of the unevenness due to the aqueous ink, and the underwater elongation was measured for each. As a result, by water elongation at <br/> remote, as having a large standard deviation in the CD direction of elongation in water,
The cockling phenomenon due to the aqueous ink was remarkable.

From the evaluation of aesthetics, etc., a sheet having a standard deviation of 30% or less, preferably 18% or less of the water elongation in water in the CD direction is adopted as a sheet having a small standard deviation. By providing a water-ink-receptive coating layer comprising a superabsorbent pigment containing fine-particle synthetic silica and a water-soluble polymer adhesive at a ratio of 0.5 to 15 g / m ^{2 on} the base paper, Inkjet paper of this type was manufactured, and it was found that it was possible to obtain an optimum ink image receiving image with a small uneven distribution of uneven size due to water-based ink absorption while maintaining a high water absorption rate of the base paper. .

That is, the present inventors have conducted various studies in order to eliminate the above-mentioned disadvantages of the prior art, and as a result, have found that the deviation of the underwater elongation of the paper is small and the paper-like or post-processed sheet-like support has been reduced. By applying a coating liquid composed mainly of superabsorbent particles and a water-soluble polymer adhesive to the body, and drying it to provide an ink-receiving coating layer, it is excellent for ink jet recording, which does not generate unevenness. It has been found that a sheet can be obtained.

The structure of the recording sheet of the present invention may be a structure using a sheet-like support as an absorber, but other structures are not excluded as long as the requirements of the present invention are satisfied.

In the present invention, the ink-receiving coating layer containing, as main components, superabsorbent fine particles such as synthetic silicic acid and a water-soluble polymer adhesive is made to have transparency, By controlling the spread,
A clear image can be obtained. The incorporation of a cationic vinyl acetate copolymer emulsion into the ink-receiving coating layer is one of the preferred means for achieving the object of the present invention for further improving the control of the permeability and the shape and spread of the ink dots.

The material used in the present invention will be described. -Papermaking sheet The papermaking sheet used in the present invention is produced by drying wet paper made by a fourdrinier paper machine or the like with a dryer. As the dryer, a Yankee dryer, a multi-cylinder dryer, or the like is used, and cellulose pulp made of ordinary wood is preferable. The thickness of the sheet is determined by the final use of the print, but is 10 to 200 μm and the basis weight is 2
Those having a surface smoothness of 0 to 200 g / m < ² > are generally used. Since a papermaking sheet is used as the absorber, a sheet having a Steckigt sizing degree of 1 to 20 seconds (in the case of a basis weight of 64 g / m ² ), particularly a sheet having a water absorption rate of 5 to 15 seconds is preferable.

Pigment The pigment used in the ink receptive coating layer of the present invention is a white pigment which has high liquid absorption and develops color. It is preferable that the main component is fine-particle synthetic silicic acid. In order to secure voids between particles for an appropriate initial, that is, short-time absorption, it is preferable to use particles having a secondary particle diameter of 1 to 5 μm with a somewhat large secondary particle as a main component. Examples of white pigments that can be used or used in addition to the fine-particle synthetic silicic acid include kaolin clay, talc, zeolite, precipitated calcium carbonate, heavy calcium carbonate, aluminum hydroxide, white carbon, and organic pigments (plastic pigments). .

Water-Soluble Polymer Adhesive As the adhesive of the present invention, a natural water-soluble polymer such as a protein such as polyvinyl alcohol or casein, or a starch derivative, or a synthetic water-soluble polymer such as polyvinyl alcohol is used as a highly water-absorbing pigment. Is preferred since it has good adhesiveness and good affinity with aqueous inks, thereby improving liquid absorption in a short time. A polymer latex adhesive such as polyvinyl acetate or styrene butadiene can also be used in combination.

The mixing ratio of components such as pigment and adhesive is as follows:
It is determined from the requirements of the absorption behavior and strength of the water-based ink-receptive coating layer, but is also limited by the requirements of the operation characteristics of the coating liquid (for example, viscosity, fluidity, and drying property of the coating film). The amount of the water-soluble polymer adhesive is 10 to 50 of the solid content of the coating layer.
% By weight, especially 20 to 35% by weight. Cationic vinyl acetate copolymer (used for emulsion polymer)
Is preferably 2 to 25% by weight of the coating layer, particularly 5 to 15% by weight.
% By weight is preferred. Further, by adding a cationic polymer emulsion, particularly vinyl acetate microspheres, to the coating layer, it is possible to impart permeability to the ink receiving layer and to improve ink absorption.

A water-based ink image can be made water-resistant by adding a cationic water-soluble polymer such as polyethyleneimine in an amount of 2 to 25% by weight of the solid content of the coating layer. The thickness of the coating layer is determined by the required amount of water absorption by the coating layer. If the coating thickness is too large, the coating layer becomes insufficient in strength and causes various problems in using paper powder in a printer.
m ² or less. If too thin initial ink absorption, the initial permeability becomes insufficient, and uniform because the coating layer is difficult to obtain a 0.5 g / m ² or more, especially 2
-10 g / m ² are preferred.

[0022]

The present invention will be described in more detail with reference to the following examples. In Examples, “parts” means “parts by weight of solid”. Example 1 100 kg bleached kraft pulp, light calcium carbonate 25
kg, cationic starch 200 g, paper strength enhancer 100 g, alkyl ketene dimer sizing agent 100 g and water 5000
mixed kg, after forming the wet paper in Fourdrinier, migraine gloss paper is brought into close contact with one side surface of the Yankee dryer and dried to 75% moisture up to 10% 58 g / m ² (support sheet - 1) was obtained. The generated paper has a single-sided Beck smoothness of 1
The smoothness of the opposite surface was 35 seconds for 35 seconds.

Water is added to 100 parts of fine silica particles (fine seal: Soda Tokuyama) having a secondary particle diameter of 2 to 5 μm of 70% or more, high-speed stirring is performed, and then silanolated polyvinyl alcohol (R) is added. -1130: Kuraray) 20 parts,
Cationic vinyl acetate copolymer (Iodosol 1E503)
K-4: Kanebo NSC) 10 parts and polyethyleneimine 10 parts were added to prepare Paint-1 (concentration 15%).

The coating material-1 was applied to one surface of the support sheet-1 at a solid content of 10 g / m ² and dried to produce a recording sheet.
The smoothness of the recording surface is 100 seconds and
Seconds. Was measured by blanking Risuto method of the coating layer, water absorption of 5 seconds was 75 ml / m ^2. The underwater elongation in the CD direction of the base paper was 1.8%, and the standard deviation of 1 cm square thereof was 15% of the underwater elongation of 1.8.

EXAMPLE 2 100 kg bleached kraft pulp, light calcium carbonate 25
kg, 200 g of cationic starch, 100 g of paper strength agent, and 80 g of alkenyl succinic anhydride were mixed with 5000 kg of water, and then formed into a wet paper web with a fourdrinier paper machine and dried from 75% to 5% with a multi-cylinder dryer. obtain high-quality paper of 75 g / m ² (the supporting sheet -2) Te. The resulting paper had a Beck smoothness of 53 seconds on one side and a smoothness of 48 seconds on the opposite side.

Water is added to 100 parts of fine silicic acid (Mizukasil: Mizusawa Chemical) having a secondary particle diameter of 6-9 μm of 70% or more, and after high-speed stirring, polyvinyl alcohol (PVA107: Kuraray) 20 parts and 10 parts of a water-soluble cationic polymer (PAS-J81: Nitto Bo) were added to prepare Paint-2 (concentration: 15%).

The support sheet solids 10 g / m ² coating paint -2 one side -2, dried to produce a recording sheet.
The smoothness of the recording surface is 100 seconds, and the degree of Stigcht size is 15
Seconds. Was measured by blanking Risuto method of the coating layer, water absorption of 5 seconds was 90 ml / m ^2. The underwater elongation in the CD direction of the base paper was 2.0%, and the standard deviation of 1 cm square thereof was 18% of the underwater elongation of 2.0.

Comparative Example 1 A wet paper was formed on a paper machine using substantially the same raw material as in Example 1, and dried from 75% to 8% in moisture with a multi-cylinder dryer to obtain 56 g / m ^2. Of both sheets (support sheet-
3 ) was obtained. The generated paper has a Beck smoothness of 3 on the felt surface.
Five seconds, the smoothness of the wire surface was 28 seconds, and the degree of Stekigt sizing was 9 seconds.

The water absorption for 5 seconds measured by the Bristow method was 25 ml / m ² . Underwater elongation of 4.1% in the CD direction of the base paper, the standard deviation of the 1cm angle underwater elongation at 4.
1 was 47%.

Comparative Example 2 Paint-1 was applied to the felt surface of the support sheet-3 of Comparative Example 1.
Was applied at a solid content of 10 g / m ² . The smoothness of the recording surface is 31
In seconds the degree of Stekigt sizing was 10 seconds. The water absorption of the coating layer measured by the Bristow method for 5 seconds is 45 ml / m.
It was ² . Underwater elongation in the CD direction of the base paper is 3.6%,
The standard deviation of the 1cm angle underwater elongation at 3. 6 was 45%. Table 1 shows the evaluation results of these recording sheets.

[0031] The amount of absorption of water per hour was measured using a blanking list tester (J.TAPP test method No51). The in-water elongation is determined by the test method of immersion elongation of paper and paperboard (J. TA).
PP No. 27). The evaluation of the ink jet recording characteristics was performed using an ink jet printer (HP
(Sink Jet) was used to evaluate the ink absorbency and unevenness after printing. For evaluation of paper irregularity, the printed portion of the printed portion was visually observed. Excellent, good, acceptable, and somewhat difficult, from those with little unevenness. For the evaluation of the ink absorbency, the number of seconds until the printed ink dries was measured. Excellent ink absorption, excellent,
Good, acceptable, slightly difficult.

[0032]

[Table 1]

[0033]

The ink jet recording sheet of the present invention has a high ink absorption rate and a large amount, and has an excellent dot shape close to a perfect circle. High-speed inkjet full color
It makes printing possible.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-95285 (JP, A) JP-A-58-8865 (JP, A) JP-A-3-199081 (JP, A) 88448 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/00

Claims (3)

(57) [Claims] [Claim 1] as a main component cellulose pulp, the 1cm square of the paper sheet standard deviation of elongation in water is less than 30% of the elongation in water in the CD direction in a unit in the sheet, the fine
The water-based ink-receptive coating layer mainly composed of a superabsorbent pigment containing particles of synthetic silica and a water-soluble polymer adhesive,
An ink jet recording sheet provided at a rate of 15 g / m ^{2 to} 15 g / m ² . 2. The papermaking sheet according to claim 1, wherein the papermaking sheet has one
The standard deviation of underwater elongation in the cm direction CD direction is
2. The ink jet recording sheet according to claim 1, which is a papermaking sheet of not more than 18%. 3. The papermaking sheet has a Stechig sizing degree of 1 to 3.
20 seconds (64 g / m ² The basis weight standard) of claim 1 or
3. The sheet for inkjet recording according to item 2.