JP3005006B2 - Ink jet recording medium - Google Patents

Description

Description: (A) Industrial application field The present invention relates to a recording medium for recording using ink, and particularly has a high ink absorbency and a high density of images and characters recorded on the medium. The present invention relates to an ink jet recording medium having excellent light fastness, ozone fastness and water fastness of an image.

(B) Prior Art The ink jet recording method has rapidly spread as a recording device for recording images, characters, and the like by causing minute droplets of ink to fly by various operating principles and adhere to a recording medium such as paper. ing. Furthermore, since images formed by the multi-color ink jet method can obtain multicolor printing by the plate-making method and recording comparable to printing by the color photographic method, it is less expensive than by photographic technology. Widely applied to the full color image field. Efforts have been made in terms of equipment and ink composition in order to use high-quality paper or coated paper used for ordinary printing and writing as a recording medium used in this ink jet recording system. However, advanced characteristics have been required for recording media such as high quality or full color. That is, as the recording medium, the density of the ink dots is high, the color tone is bright and vivid, the ink does not flow out or bleeds even when the ink dots are quickly absorbed, and the ink dots The diffusion in the horizontal direction is not unnecessarily large, and the periphery is smooth and not blurred. Further, it is required that the dye resistance when the recorded image is exposed to ultraviolet light, oxygen in the air or water is not reduced, but is preferably enhanced.

In order to solve these problems, as described in JP-A-57-87987, the light fastness of a recorded matter is disclosed in JP-A-55-11879.
No. 829, as disclosed in
Various proposals have heretofore been made, as disclosed in JP-9988A as a means for improving the absorption of ink dots.However, a recording medium having excellent ink absorption, water resistance and excellent light resistance has been completed. I didn't.

(C) Problems to be Solved by the Invention As is apparent from the above-mentioned prior art, various proposals have been made to solve the problems of the recording medium in the ink jet recording system, and improvements have been made. A recording medium having good light resistance and water resistance and excellent light resistance has not been completed.

 An object of the present invention is to solve the above problems.

(D) Means for Solving the Problems That is, the present invention is directed to recording using an aqueous ink containing at least one water-soluble dye among direct dyes, acid dyes, basic dyes, reactive dyes, and food dyes. In an ink jet recording medium for forming an image, the recording medium is formed on a paper layer by coating barium sulfate, gelatin and gelatin obtained by reacting neutral crystalline sodium sulfate and neutral crystalline barium chloride with a hardener. An ink jet recording medium characterized by having a layer, more specifically, a weight ratio of barium sulfate to gelatin is 8 to 12 parts by weight of gelatin with respect to 100 parts by weight of barium sulfate, and the coating amount is
An inkjet recording medium having a weight of 5 g / m ² or more and 80 g / m ² or less.

Further, the barium sulfate obtained by reacting the neutral crystalline sodium sulfate and the neutral crystalline barium chloride used in the present invention has little sulfide impurities, little discoloration of barium sulfate, very good light fastness, and forms an ink jet recorded image. The color tone at this time is clear and preferable.

As a method for producing barium sulfate, specifically, one solution is added with a 5 to 20% aqueous solution of neutral crystalline sodium sulfate and a 5 to 20% aqueous solution of neutral crystalline barium chloride while the other solution is added. , To produce barium sulfate. The sulfide content of barium sulfate obtained by this method is 0.01 ppm or less. In other methods, for example, barium sulfate obtained from barium sulfide and sulfuric acid or sodium sulfate contains about 0.1 ppm or more of sulfide, so that when used in an ink jet recording medium, the coating layer is severely discolored and the light resistance is reduced.

The average particle diameter of barium sulfate is 0.8 μm or more.
μm or less is preferred. When the average particle size is smaller than 0.8 μm, the viscosity of the coating liquid increases, and the adhesiveness is unfavorably deteriorated.

On the other hand, if the average particle size is larger than 3 μm, the smoothness of the surface is inferior and uneven absorption occurs, which is not preferable.

As the adhesive used in the present invention, gelatin is used, and there are various kinds of gelatin such as acid-treated gelatin and alkali-treated gelatin.

Gelatin is preferably 8 to 12 parts by weight based on 100 parts by weight of barium sulfate. If the amount is less than 8 parts by weight, the adhesiveness and water resistance of the coating layer are unfavorably poor. On the other hand, if the amount is more than 12 parts by weight, the viscosity of the coating liquid increases and the cost increases, which is not preferable. Examples of hardeners for gelatin include hardeners such as chromium sulfate, chrome-amber, formalin, triazine, epoxy, urea formalin, and melamine. Among them, hardeners that are soluble in water-soluble media such as water-soluble or alcohol. And
These may be used alone or in combination. The addition amount is preferably 0.2 to 4 parts by weight based on 100 parts by weight of gelatin. If the added amount is less than 0.2 parts by weight with respect to 100 parts by weight of gelatin, there is no effect as a hardener and water resistance is poor. If the added amount is more than 4 parts by weight with respect to 100 parts by weight of gelatin, the viscosity of the coating liquid increases, the liquid property becomes unstable, and coating unevenness occurs, the coating amount fluctuates, and a constant coating layer is obtained. Hateful.

The coating amount is preferably from ^{5g / m 2 ~80g / m 2} , in particular coating amount is 10g
/ m ² or more and up to 50 g / m ² . If the coating amount is less than 5 g / m ² , the ink absorbency is poor, which is not preferable. 80g /
If it is larger than m ² , a coating surface, for example, a pinhole or a coating streak tends to occur, which is not preferable. Also not economical.

The drying method is not particularly specified. A normal coating paper drying method is used. As other additives, a pigment dispersant, an antifoaming agent, an antifoaming agent, a coloring dye, a coloring pigment, a water-proofing agent, a preservative, and the like can be appropriately compounded.

The paper used in the present invention is 60 to 30
It may be about 0 seconds of paper and may or may not contain filler. As the sizing agent, a neutral sizing agent is preferably used, but an acidic paper using a conventionally known rosin sizing agent may be used. Examples of the neutral sizing agent include an alkyl ketene dimer, an epoxidized higher fatty acid amide, and a cationized styrene-maleic anhydride copolymer. In the present invention, an alkyl ketene dimer sizing agent is preferably used. One or a combination of these sizing agents can be used to produce paper with a Stöckicht sizing degree of 60-300 seconds. When the Steckigt sizing degree is less than 60 seconds, the water resistance is poor, and it is unsuitable for use as a back image for TV (hereinafter abbreviated as TV back paper) and for outdoor poster. The Stekigt sizing degree may be greater than 300 seconds, but excessively increasing the sizing degree only increases the cost and has little effect on the effects of the present invention, so up to 300 seconds is a practical range. is there. Further, as a size press at the time of production, for example, oxidized starch, gelatin or the like may be applied by a size press device.

(E) Action The present invention provides a water-soluble dye by providing, on a paper layer, a coating layer comprising barium sulfate, gelatin and a gelatin hardener obtained by reacting neutral crystalline sodium sulfate with neutral crystalline barium chloride. Have found an ink jet recording medium having good ink absorbency, excellent light fastness and water fastness of an image recorded on the medium, and low cost.

(F) Examples Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.

Example 1 80 parts by weight of LBKP with a freeness of 370 ml CSF, NB with a freeness of 400 ml CSF
Cationic starch 0.5 was added to a pulp slurry consisting of 20 parts by weight of KP.
0.5 parts by weight of an alkyl ketene dimer and 0.2 parts by weight of epichlorohydrin were added to make a paper having a basis weight of 150 g / m ² , to obtain a base paper having a Steckigt sizing degree of 200 seconds. 100 parts by weight of barium sulfate obtained by reacting neutral crystalline sodium sulfate and neutral crystalline barium chloride in this base paper in an aqueous solution,
A coating liquid was prepared by mixing 8 parts by weight of gelatin and 0.24 parts by weight of chromium sulfate (0.3% by weight based on gelatin) as a hardener. This coating solution was applied at 40 g / m ² with an air knife coater, the coating layer temperature was reduced to 20 ° C. or lower, and then dried at 30 ° C. to 60 ° C. to obtain an ink jet recording medium.

Example 2 100 parts by weight of barium sulfate, 11 parts by weight of gelatin, a hardener, and chromium sulfate were added to the base paper used in Example 1 as in Example 1.
A coating liquid was prepared by mixing 0.33 parts by weight. This coating solution was applied at 40 g / m ² using an air knife coater as in Example 1, and dried as in Example 1 to obtain an ink jet recording medium.

Example 3 The coating liquid applied in Example 2 was applied to the base paper used in Example 1 with an air knife coater at 5 g / m ^{2 in the same} manner as in Example 1, and dried to obtain an ink jet recording medium.

Example 4 The base paper used in Example 1 and the coating solution used in Example 2 were applied in the same manner as in Example 1 with an air knife coater at 78 g / m ² and dried as in Example 1 to obtain an ink jet recording medium.

Comparative Example 1 To the base paper used in Example 1, 100 parts by weight of barium sulfate obtained from barium sulfide and sodium sulfate, 11 parts by weight of gelatin, and 0.33 parts by weight of chromium sulfate hardener (0.3% by weight based on gelatin) It was blended to prepare a coating solution. This coating liquid was applied at 40 g / m ² using an air knife coater and dried in the same manner as in Example 1 to obtain an ink jet recording medium.

Example 5 80 parts by weight of LBKP with a freeness of 370 ml CSF, NB with a freeness of 400 ml CSF
Cationic starch 0.5 was added to a pulp slurry consisting of 20 parts by weight of KP.
By weight, 0.1 parts by weight of an alkyl ketene dammer and 0.2 parts by weight of epichlorohydrin were added, and a paper having a basis weight of 150 g / m ² was formed to obtain a base paper having a Steckigt sizing degree of 40 seconds. The coating liquid used in Example 2 was applied to this base paper with an air knife coater at 40 g / m ² as in Example 1, and dried as in Example 1 to obtain an ink jet recording medium.

Example 6 80 parts by weight of LBKP with a freeness of 370 ml CSF, NB with a freeness of 400 ml CSF
Cationic starch 0.5 was added to a pulp slurry consisting of 20 parts by weight of KP.
Parts by weight, 0.8 parts by weight of alkyl ketene dammer, and 0.2 parts by weight of epichlorohydrin were added to form a paper having a basis weight of 150 g / m ² to obtain a base paper having a Steckigt size of 400 seconds. The coating liquid used in Example 2 was applied to this base paper with an air knife coater at 40 g / m ² in the same manner as in Example 1, and dried in the same manner as in Example 1,
An ink jet recording medium was used.

Comparative Example 2 100 parts by weight of barium sulfate, 11 parts by weight of gelatin, and no hardened chromium sulfate were blended with the base paper used in Example 1 to prepare a coating solution. This coating solution was applied at 40 g / m ² using an air knife coater as in Example 1, and dried as in Example 1 to obtain an ink jet recording medium.

Comparative Example 3 100 parts by weight of the same barium sulfate and gelatin as in Example 1 were replaced with polyvinyl alcohol in the base paper used in Example 1, 11 parts by weight, and a hardening agent chromium sulfate was 0.33 parts by weight (3% based on polyvinyl alcohol). ) Was blended to prepare a coating solution.
The coating solution 40 g / m ² was applied by an air knife coater, 100
It dried at ℃ and used as an inkjet recording medium.

The ink jet suitability of the ink jet recording media of Examples 1 to 6 and Comparative Examples 1 to 3 was measured, and the results are shown in Table 1.

The inkjet suitability was measured by the following method.

Light fastness is measured by Canon inkjet printer (A-
1210), using a xenon fade meter (Suga Test Instruments Co., Ltd., FAL-25X-HCL type) at 40 ° C., 60%, illuminance 4
Irradiation at 1 w / m ² for 40 hours, and separate exposure to direct sunlight for 24 hours. Before and after xenon light irradiation or sunlight exposure, the sensory chromaticity (La, ab) was measured using a colorimeter (CR-100, Using a Minolta camera) and measuring the sensory chromaticity before and after irradiation (△
The color difference ΔE was obtained from L, Δa, and Δb). This value was evaluated as the amount of discoloration.

The water resistance of the coating layer was determined by using the same Canon inkjet printer to solid print with each ink of cyan (C), magenta (M), yellow (Y) and black (BK). It was immersed for 3 minutes, and the printed portion was rubbed with a finger while wet, and the extent to which the ink moved as a stain other than the printed portion was visually determined. Those that are not stained have better water resistance.

The ink absorption speed is determined by using a sharp or Canon inkjet printer, feeding paper immediately after red printing (magenta + yellow) solid printing (after about 1 second), and contacting it with a paper press roll or a finger. It was determined whether to go out or not.

Those with no stains have good ink absorption speed and are good.

The evaluation results were classified into three stages: ○: excellent, Δ: practicable, ×: same as conventional.

As is clear from the above Examples and Comparative Examples, the present invention provides a barium sulfate obtained by reacting neutral crystalline sodium sulfate with neutral crystalline barium chloride, gelatin and a hardened image of gelatin when a hardener of gelatin is used. A recording medium having improved water fastness and light fastness and having good coating layer water fastness and ink absorption speed was obtained.

(G) Effects of the Invention The present invention occurs when barium sulfate, gelatin, and a hardener obtained by reacting neutral crystalline sodium sulfate with neutral crystalline barium chloride are used, and other pigments and binders are used. Deterioration of light resistance of the recorded image, poor water resistance of the coating layer,
It is possible to obtain a well-balanced recording medium having few defects in ink jet recording, particularly color recording, in which the ink absorption speed and the like are improved in light resistance, coating layer water resistance, ink absorption speed and the like.

Claims (5)

(57) [Claims] 1. An ink jet recording medium for forming a recorded image using an aqueous ink containing at least one water-soluble dye among direct dyes, acid dyes, basic dyes, reactive dyes and food dyes. Wherein the recording medium has a coating layer comprising barium sulfate, gelatin and gelatin hardened by reacting neutral crystalline sodium sulfate and neutral crystalline barium chloride on a paper layer. recoding media. Wherein the ratio of the weight of barium sulfate and gelatin is 8 parts by weight of gelatin to 12 parts by weight per 100 parts by weight of barium sulfate, and it Nuriso weight is 5g / m ² ~80g / m ² The ink jet recording medium according to claim 1, wherein: 3. A process according to claim 1 coated layer weight is 10g / m ² ~50g / m ²
Or the inkjet recording medium of 2. 4. The paper layer has a Stighit sizing degree of 60 seconds to 300 seconds.
2. The ink jet recording medium according to claim 1, wherein the time is seconds. 5. A barium sulfate having a sulfide content of 0.01 ppm.
2. The ink jet recording medium according to claim 1, wherein: