JPH0939376A - Glossy paper - Google Patents

Abstract

(57) [PROBLEMS] To obtain a recording medium having good ink absorbency and free from beading or bleeding. A porous alumina hydrate layer is provided on a paper substrate, and the surface has a 60-degree specular gloss of 20% or more as defined by JIS Z8471 and a mesh-like crack on the surface. Glossy paper with.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to glossy paper, and more particularly to glossy paper suitable for recording by an ink jet printer.

[0002]

2. Description of the Related Art Glossy paper, that is, paper having a smooth surface and a high gloss, is manufactured by a method such as cast coating and calendering. For example, the cast coat method is
In the case of producing coated paper, the coated surface in a wet state is pressed by a smooth mold surface and heated and dried to obtain a smooth coated surface.

[0003]

The glossy paper is inferior to the non-gloss coated paper in absorbency and beading property because the glossy paper develops gloss due to the smoothness of the surface. In order to satisfy these, it is necessary to increase the coating amount or mix an additive having a large ink absorption capacity, such as silica gel. An object of the present invention is to provide a glossy paper having excellent absorbency and anti-beading property.

[0004]

The present invention has a porous alumina hydrate layer on a paper substrate, the surface of which is JIS Z8.
Provided is a glossy paper having a 60-degree specular gloss of 20% or more defined by 471 and having a network of cracks on the surface.

Here, the term "mesh-like cracks" means that the alumina hydrate porous layer is divided into fine polygons by the cracks. That is, the cracks are growing well and the edges of all the cracks extend substantially to the other cracks.
Only partially, the crack edges may remain inside the polygon.

In polygons defined by cracks, it is preferable that the circumscribed circles have an average diameter of 200 μm or less, and particularly 90% or more of the polygons whose circumscribed circles have a diameter of 200 μm or less on a number basis. Is preferred. This value is obtained by observing with a microscope and measuring the diameter of the circumscribing circle for a polygon included in a 1 mm square.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The paper substrate is not particularly limited,
Various ones can be used.

As the alumina hydrate layer formed on the substrate, boehmite (Al ₂ O ₃ .nH ₂ O, n = 1 to 1)
It is preferable that it is composed of 1.5) because the ink absorbency of the inkjet ink is good and the fixing property of the dye in the ink is excellent.

The alumina hydrate porous layer preferably has a structure in which alumina hydrate particles are bound by an organic binder. As the binder, polyvinyl alcohol and its modified products, starch and its modified products, SBR latex,
Organic substances such as NBR latex, carboxymethyl cellulose, hydroxymethyl cellulose and polyvinylpyrrolidone can be used. The amount of the binder used is preferably about 5 to 50% by weight of the alumina hydrate. When the amount of the binder used is less than 5% by weight, the strength of the porous layer may be insufficient. On the contrary, when it is more than 50% by weight, the ink absorption or the dye adsorption is insufficient. Therefore, it is not preferable because it may result in

The alumina hydrate porous layer has a pore structure having a pore radius of 1 to 30 nm and a pore volume of 0.3 to 1.2 c.
m ³ / g, of which the pore volume with a pore radius of 10 to 30 nm is 0.2 to 1.0 cm ³ / g, the pore radius is 30 to 100 n
A pore volume of m of 0.3 cm ³ / g or less is preferable because it has sufficient absorptivity and enables recording with high color density.

When the alumina hydrate is boehmite and the b-axis of the boehmite crystal is oriented perpendicularly to the surface of the substrate, it is particularly preferable because the absorptivity and the color density are good.

In the porous layer containing boehmite,
The b axis of the boehmite crystal needs to be oriented perpendicular to the substrate surface. When the b-axis of boehmite is not oriented perpendicular to the sheet surface, the transparency of the porous layer is impaired even when it has the above-mentioned pore characteristics, and when the substrate is transparent, haze Is high, which is not preferable.
Here, the degree of orientation is [0 of boehmite obtained by X-ray diffraction.
The ratio of the peak height due to the reflection of the [20] plane and the [200] plane is measured on the glossy paper surface by a thin film X-ray diffraction method, and is defined by comparison with non-oriented boehmite powder. That is, the degree of orientation is defined as follows.

[0013]

[Equation 1]

[0014]

[Equation 2]

If the degree of orientation value is 1, the boehmite is non-oriented. The smaller this value, the higher the degree of orientation,
If so, it indicates perfect b-axis orientation, that is, the b-axes of all boehmite crystal grains are perpendicular to the sheet surface. If the degree of orientation of boehmite exceeds 0.5, the transparency of the boehmite layer will be insufficient, which is unsuitable. In the glossy paper of the present invention, since the dye is carried in the highly transparent layer, it is possible to record with good color development and high color density. It is more preferable that the degree of orientation of boehmite is 0.3 or less.

The thus-oriented porous layer containing boehmite is formed by applying a coating liquid containing boehmite sol. This is mainly due to the anisotropy of the boehmite crystal, and it is considered that the b-axis is oriented vertically on the substrate during the drying process of the boehmite sol coating liquid. The same applies not only when the boehmite crystal particles are monodispersed in the boehmite sol but also when the sol particles are secondary aggregated to some extent. However, by applying the powder obtained by crushing boehmite xerogel to a substrate together with a binder, a boehmite layer oriented in this way cannot be obtained.

The thickness of the alumina hydrate porous layer is appropriately selected according to the specifications of the printer, etc., and is generally 5-10.
It is preferable to adopt 0 μm. If the thickness of the ink receiving layer is less than 5 μm, the ink absorbency may be insufficient or the dye may not be sufficiently adsorbed, and if it exceeds 100 μm, the transparency of the ink receiving layer may be impaired or the strength of the layer may be reduced. Are likely to decrease, which is not preferable. The coating amount is preferably in the range of 5 to 30 g / m ² .

In the present invention, the absorptivity of the paper substrate can be fully utilized by forming the mesh-like cracks. Cracks that the alumina hydrate porous layer has, the molecular weight of the binder mixed in the alumina hydrate layer, the saponification degree,
It can be variously set depending on the addition amount or the coating amount of the boehmite layer. For example, when polyvinyl alcohol is used as the binder, it is preferable to use one having a polymerization degree of 300 to 2000 and a saponification degree of 85 mol% or more. As the coating amount of the alumina hydrate, particularly 10 to 25
It is preferably in the range of g / m ² .

The method for forming the alumina hydrate porous layer on the substrate is not particularly limited. A method of applying a coating liquid formed by adding a binder and a solvent to alumina hydrate to a substrate and then drying the coating liquid is preferable. It is preferable to use alumina sol as a raw material for alumina hydrate because a porous layer having good transparency can be formed. The application method of the coating liquid is
For example, a die coater, roll coater, air knife coater, blade coater, rod coater, bar coater, comma coater or the like can be adopted. As a solvent for the coating liquid, either an aqueous system or a non-aqueous system can be adopted.

In the present invention, a so-called cast coating method is preferably adopted as a method for imparting a predetermined gloss. That is, the coating liquid applied on the base material by the above method presses the mold having a smooth surface to impart smoothness before completely drying. As a result, JIS
A glossy paper having a 60-degree specular gloss of 20% or more specified by Z8471 can be obtained. It is more preferable that the glossiness is 30% or more.

[0021]

【Example】

Example 1 100 parts by weight of a synthetic boehmite sol that forms a xerogel having an average pore radius of 10.2 nm when dried, 11 parts by weight of polyvinyl alcohol (PVA105, manufactured by Kuraray Co., Ltd.) having a polymerization degree of 500 and a saponification degree of 99 mol%. Was added, and then water was added to prepare a coating liquid having a solid content concentration of 18% by weight. This was coating liquid was coated using a bar coater so that the basis weight 127 g / dried fine paper of m ² coating amount 15 g / m ^2. The water content (water content / solid content) immediately after coating is 4
56%. This was dried to reduce the water content to 250%. This was brought into close contact with a mold having a mirror surface heated to 90 ° C. at a linear pressure of 10 kg / cm and dried, and then peeled off to obtain a glossy paper having a glossy coating layer. This glossy paper is
The surface had mesh-like cracks.

Example 2 A polymerization degree of 17 was added to 100 parts by weight of a synthetic boehmite sol which forms a xerogel having an average pore radius of 8 nm when dried.
At 100, 100 parts by weight of polyvinyl alcohol (PVA117 manufactured by Kuraray Co., Ltd.) having a saponification degree of 99 mol% was added, and water was further added to prepare a coating liquid having a solid content concentration of 18% by weight. Using this coating solution, a glossy paper was obtained in the same manner as in Example 1. This glossy paper had mesh-like cracks on the surface.

Example 3 100 parts by weight of synthetic boehmite sol which forms a xerogel having an average pore radius of 10.2 nm when dried is polyvinyl alcohol having a degree of polymerization of 500 and a degree of saponification of 99 mol% (PVA105, manufactured by Kuraray Co., Ltd.). 5.5 parts by weight,
5 parts by weight of dextrin and 0.5 part by weight of glutaraldehyde (crosslinking agent for dextrin) were added, and water was further added to prepare a coating solution having a solid content concentration of 18% by weight. Using this coating solution, a glossy paper was obtained in the same manner as in Example 1. This glossy paper had mesh-like cracks on the surface.

Example 4 100 parts by weight of a synthetic boehmite sol which forms a xerogel having an average pore radius of 10.2 nm when dried is polyvinyl alcohol having a degree of polymerization of 2600 and a degree of saponification of 96.5 mol% (Shin-Etsu Chemical Co., Ltd.). Made, MA-26GP)
11 parts by weight was added, and water was further added to prepare a coating liquid having a solid content concentration of 18% by weight. Using this coating solution, a glossy paper was obtained in the same manner as in Example 1. There were no cracks on this glossy paper.

Example 5 100 parts by weight of synthetic boehmite sol which forms a xerogel having an average pore radius of 10.2 nm when dried is polyvinyl alcohol having a degree of polymerization of 500 and a degree of saponification of 99 mol% (PVA105 manufactured by Kuraray Co., Ltd.). 5.5 parts by weight,
Polyvinyl alcohol having a polymerization degree of 2600 and a saponification degree of 96.5 mol% (MA-26G manufactured by Shin-Etsu Chemical Co., Ltd.)
P) (5.5 parts by weight) was added, and water was further added to prepare a coating solution having a solid content concentration of 18% by weight. Using this coating solution, a glossy paper was obtained in the same manner as in Example 1. This glossy paper had mesh-like cracks on the surface.

Example 6 The same coating solution as in Example 1 was applied so that the dry coating amount was 15 g / m ^2, and the water content was adjusted to 250% by drying.

On this boehmite layer, 100 parts by weight of a silica sol having an average primary particle diameter of 35 to 45 nm (manufactured by Catalysts & Chemicals Industry Co., Ltd., SI45P) and silanol-modified polyvinyl alcohol (Kuraray Co., Ltd., R1130).
A coating liquid containing 10 parts by weight and water and having a solid content of 1% by weight was prepared and applied so that the dry coating amount was 0.2 g / m ² . At this time, the water content was 350%. 90 ° C
It was brought into close contact with a mold having a mirror surface heated to a linear pressure of 10 kg / cm, dried, and then peeled off to obtain a glossy paper. This glossy paper had mesh-like cracks on the surface.

Evaluation The 60-degree specular gloss of the above glossy paper was measured using a gloss meter 300A manufactured by Nippon Denshoku Co., Ltd. The crack shape of the coating layer and the average value of the diameter of the circle circumscribing it were determined by microscopic observation. The results are as follows.

[0029]

[Table 1]

Printing On the above recording medium, a test pattern was printed with a black ink containing hood black 2 as a dye using an inkjet printer (manufactured by Seiko Epson Corporation, trade name MJ700). Table 2 shows the results of relative evaluation of the absorptivity, the bead (anti-beading resistance), and the image on a scale of 5 points.

[0031]

[Table 2]

[0032]

INDUSTRIAL APPLICABILITY The glossy paper of the present invention can fully utilize the absorbability of the paper base material, has high ink absorbency, and does not cause beading. Also, since the gloss does not become too high, the image quality is suppressed and the gloss becomes calm.

Claims (1)

[Claims] 1. A paper hydrate having a porous layer of hydrated alumina, having a 60-degree specular gloss of 20% or more defined by JIS Z8471 and having a mesh-like surface. Glossy paper with cracks.