JP2000177240A - Image recording medium for ink jet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording medium having an ink acceptable layer on a paper base body capable of obtaining an image of high quality and superior weatherability. SOLUTION: The ink jet recording medium is formed such that it has at least two layers of ink acceptable layers on a paper base body, the uppermost surface layer of which consists of porosity containing a thermoplastic latex resin, and also it can be subjected to a heat transparency treatment, and further its apparent density is 0.95-1.15 g/cm3 according to JISP8118 of the paper base body.

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 medium in which, after a visible image is formed, the outermost surface of the image is subjected to a transparency treatment.

[0002]

2. Description of the Related Art A conventional ink-jet image forming apparatus comprises:
The mainstream is to form an image by forming a visible image using an ink such as a dye or a pigment on a recording medium. However, such a configuration has disadvantages such as discoloration or fading of the visible material due to light or ozone when the recording medium is stored, and bleeding of an image due to contact with moisture. There is also a problem that the gloss of a visible image cannot be sufficiently obtained.

On the other hand, JP-A-7-237348 and JP-A-8-2090 disclose an ink absorbing layer as a recording medium used in this type of image formation in order to improve the water resistance and weather resistance of the image. It is disclosed that a latex layer is further provided on the substrate and the latex layer is heated to form a transparent film after inkjet recording.

[0004]

However, according to the above-mentioned conventional example, when the latex layer is heated and formed into a film by hot air drying, it is difficult to uniformly and uniformly heat the recording medium, and the film is formed efficiently. There was a problem that was not done. As a means for solving the problem, there is a method in which a latex layer is uniformly and efficiently formed into a film by heating a recording medium while pressing the recording medium from both sides with two heated rubber rollers. However, in the case of a recording medium using paper as the base material, the recording medium is delaminated in the thickness direction of the medium by pressing and heating with a roller, thereby significantly degrading the quality of the ink jet recording medium. In addition, when printing is performed by an ink jet printer having the built-in heating / pressing roller and the heating / pressing is performed in-line, there has been a problem that the recording medium having undergone delamination jams in the printer.

An object of the present invention is to provide an image recording medium which can form a uniform film of a latex layer by heating and pressurizing the latex layer and has good image recording characteristics.

[0006]

The image recording medium of the present invention which solves the above-mentioned problems has at least two ink-receiving layers on a paper substrate, and the outermost layer is formed of a porous layer containing a thermoplastic latex resin. An inkjet recording medium whose outermost layer can be heated and made transparent after inkjet recording, wherein the apparent density of the paper substrate according to JISP8118 is 0.95 to 1.15 g / cm ^3. Things.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The above-mentioned delamination of a recording medium was examined. The delamination occurred not between the base paper and the ink absorbing layer or between the ink absorbing layer and the latex layer. It was found that the paper itself as the substrate itself caused delamination. In this delamination, the recording medium is inkjet-recorded, and the paper, which is a substrate that has absorbed the ink solvent, is heated by a roller, so that the solvent component in the substrate rapidly evaporates and expands. It occurs when the bond is broken.

It has been found that the above-mentioned paper substrate only needs to have an apparent density according to JISP8118 of 0.95 to 1.15 g / cm ³ in order to prevent this delamination.

When the density is less than 0.95 g / cm ³ , the paper substrate is liable to undergo delamination when heated and pressurized after ink-jet recording, and when the density exceeds 1.15 g / cm 3, the ink is deposited inside the paper substrate. Voids for absorbing the solvent are reduced, the ink absorbing ability of the recording medium is reduced, and ink aggregation called beading occurs on the surface of the recording medium in a color overlapping portion, thereby deteriorating image recording characteristics.

Hereinafter, the recording medium of the present invention will be described in detail.

The recording medium used in the image forming method of the present invention has at least two ink receiving layers on a paper substrate, and the outermost layer has a porous layer containing a thermoplastic latex resin. The heat treatment of the surface layer turns the latex into a film and makes it transparent.

The latex of the outermost layer includes vinyl chloride, vinyl chloride-vinyl acetate, SBR, NBR,
Acrylic-based, urethane-based, polyester-based, and ethylene-based latexes can be mentioned, and vinyl chloride-vinyl acetate-based latex is more preferable in consideration of ink permeability.

The second ink receiving layer, which is a lower layer below the layer containing the latex resin, which is the outermost layer, needs to completely and rapidly absorb ink permeating the upper layer of the latex layer. Materials having a large ink absorption capacity include light calcium carbonate, aluminum hydroxide, synthetic alumina, amorphous silica, and the like.To obtain a high-absorption and high-quality image, a porous material containing alumina hydrate is used. Layers are preferred.

Further, as the pulp constituting the above paper substrate, natural pulp and synthetic pulp can be used, for example, but natural pulp is generally used.

[0015] Natural pulp is subjected to ordinary bleaching treatment of chlorine, hypochlorite, chlorine dioxide bleaching, alkali extraction or alkali treatment, oxidative bleaching treatment with hydrogen peroxide, oxygen or the like if necessary, and a combination treatment thereof. Wood pulp of softwood pulp, hardwood pulp, and softwood pulp mixed pulp treated with pulp is used, and various pulp such as kraft pulp, sulfite pulp, soda pulp, and the like can be used.

The base paper may contain various additives at the time of preparing the stock slurry, and it is advantageous to use a sizing agent containing a fatty acid metal salt or / and a fatty acid, a rosin derivative or the like.

The apparent density on the paper substrate can be adjusted by machine calendering after papermaking.

If the thermoplastic latex resin layer is also provided on the back surface of the recording medium, the water resistance of the recording medium can be improved.
This is more preferable because the strength of the recording medium can be further improved.

[0019]

EXAMPLES The characteristics of the recording medium according to the present invention and the prior art were evaluated by the following methods. 1) Recording Characteristics An ink jet printer having 128 ink jet heads each having a nozzle interval of 16 nozzles per 1 mm for four colors of yellow (Y), magenta (M), cyan (C), and black (Bk). The ink amount of 200% when the ink amount in monochromatic printing is set to 100% on the surface of the recording medium after solid printing of each of Y, M, C, and Bk inks in multicolor on an A4 size recording medium. The beading at% was visually evaluated. 2) Presence or absence of delamination The above-mentioned A4 size printed matter was heated to form a latex layer, and the presence or absence of delamination was visually evaluated. 3) Curl The curl amount at the four corners of the A4 size recording medium having the latex layer formed thereon was measured.

Example 1 A hardwood bleached kraft pulp was used as a raw material pulp.
After the papermaking, machine calendering was performed at a linear pressure of 60 kg / cm to produce a paper substrate having a basis weight of 150 g / m ² and a density of 0.95 g / cm ³ .

Next, alumina hydrate was used for the ink receiving layer, and the adjustment was performed as follows. Aluminum octoxide was synthesized according to the method described in U.S. Pat. No. 4,242,271, and hydrolyzed to produce an alumina slurry. Water was added to the alumina slurry until the alumina hydrate had a solid content of 5%. Next, after raising the temperature to 80 ° C. and performing an aging reaction for 10 hours, this colloidal sol was spray-dried to obtain an alumina hydrate.

Further, this alumina hydrate was mixed and dispersed in ion-exchanged water, and adjusted to pH 10 with nitric acid. The aging time was 5 hours to obtain a colloidal sol. After desalting the colloidal sol, deflocculation was performed by adding acetic acid.

The colloidal sol of alumina hydrate was concentrated to obtain a 15% by weight solution. On the other hand, polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray) was dissolved in ion-exchanged water to obtain a 10% by weight solution. The two solutions were mixed so that the solid content of alumina hydrate and the solid content of polyvinyl alcohol were in a weight ratio of 10: 1, and stirred to obtain a dispersion.

The dispersion was coated on the paper substrate with a dry coating amount of 3
A coating layer was formed at 0 g / m ² .

Further, on this alumina layer, a solid content of 15%
Vinyl chloride-vinyl acetate-based latex (trade name: ViniBlank 602, manufactured by Nissin Chemical Industry Co., Ltd.) to form a porous latex layer with a dry coating amount of 5 g / m ² , and an A4 size recording medium I got

After ink-jet recording was performed using the above-mentioned recording medium, an A4 size printed matter was passed through a pair of rubber rollers and heated under pressure to form a latex layer, thereby obtaining a printed matter.

The material of the heating and pressing roller is 2 m thick.
A 0.5 mm LTV silicone rubber is mirror-finished on an HTV silicone rubber of m.
It is a measurement method of 40 ° as determined by type A in 301. The transport speed of the recording medium was 14 mm / sec, and the surface temperature of the roller was 170 ° C. to form a latex layer.

This print recorded matter was of good quality with no beading, no delamination of the paper substrate, and a curl of about 2 mm.

Comparative Example 1 A paper substrate was produced in the same manner as in Example 1 except that the linear pressure during machine calendering was set to 20 kg / cm.
A paper substrate having g / m ² and a density of 0.80 g / cm ³ was obtained.

Then, the ink receiving layer 2 was formed in the same manner as in Example 1.
The layers were stacked to obtain an A4 size recording medium.

Using the above recording medium, image recording was performed in the same manner as in Example 1, and passed through a pair of rubber rollers under pressure and heated to form a latex layer as in Example 1. At this time, delamination did not occur on the paper substrate in the portion where the ink jet recording was not performed, but interlayer separation of the paper substrate occurred in the portion where a large amount of ink was recorded at 200%, and the quality of the recorded matter was remarkably reduced. I lost it.

Comparative Example 2 The same ink-jet recording as in Example 1 was carried out on the same recording medium as in Comparative Example 1, and the latex layer was formed into a film with a hot-air drier to obtain an A4-size printed recording.

This printed recording did not cause delamination of the paper substrate, but had poor flatness, and the four corners of the A4 plate had 5 to 6 c
m has curled.

Comparative Example 3 A paper substrate was produced in the same manner as in Example 1 except that the linear pressure during machine calendering was set to 120 kg / cm.
A paper substrate having 0 g / m ² and a density of 1.30 g / cm ³ was obtained.

In the same manner as in Example 1, the ink receiving layer 2
The layers were stacked to obtain an A4 size recording medium.

Using the above-described recording medium, ink jet recording was performed in the same manner as in Example 1, and passed through a pair of rubber rollers under pressure and heated to form a latex layer as in Example 1. At this time, no delamination of the paper substrate occurred in the printed recorded material, but beading occurred in a portion where a large amount of ink was recorded as large as 200%, resulting in poor ink absorbency and poor recording characteristics. I have.

Example 2 A paper substrate was produced in the same manner as in Example 1 except that the linear pressure during the machine calendering treatment was changed to 100 kg / cm.
A paper substrate having 0 g / m ² and a density of 1.15 g / cm ³ was obtained.

In addition, as in Example 1, the ink receiving layer 2
The layers were stacked to obtain an A4 size recording medium.

Using the above recording medium, ink jet recording was performed in the same manner as in Example 1, and passed through a pair of rubber rollers under pressure and heated to form a latex layer as in Example 1.

This printed matter did not generate beading, had no delamination of the paper substrate, and had a curl of about 2 mm, of good quality.

[0041]

As described above, according to the present invention,
By limiting the density of the paper substrate used, the latex layer of the ink jet recording medium can be heated and pressed to form a uniform film of the latex layer without delamination, resulting in high quality and excellent weather resistance. Images can be obtained.

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 2H086 BA05 BA16 BA21 BA34 BA41 4F100 AA19 AK01C AK15 AK21 AK22 BA03 BA07 BA10A BA10C BA26 DG10A DJ00C EH46 EJ19 EJ42 GB90 JA13A JB16C JD14B JD14J JK01 JL01

Claims (2)

[Claims] 1. An ink receiving layer having at least two layers on a paper substrate.
An ink-jet recording medium having an outermost layer comprising a porous layer containing a thermoplastic latex resin and capable of subjecting the outermost layer to heat-clearing treatment after ink-jet recording, wherein the apparent density of the paper substrate is determined by JISP8118. Is 0.95 to 1.15 g / cm ³ . 2. The ink jet recording medium according to claim 1, wherein a heating / pressurizing roller is used as the heating / clearing processing means for the outermost layer of the recording medium.