JPH03143678A - Recording material - Google Patents

Abstract

PURPOSE:To prevent an image from becoming white without impairing the transparency of a base material with the provision of an ink absorption layer for enabling full color realization by selecting the surface smoothness of an ink receiving layer formed on a transparent base within a specific range. CONSTITUTION:An ink receiving layer with a 10-point average roughness of less than 0.05 mum is provided on a transparent layer. This value is necessary for the ink receiving layer. Unless this requirement is met, light scatters, and transparency is impaired resulting in the improper visualization of an image which becomes whitish. The material used for the ink receiving layer is a porous material such as silica or alumina. Especially it is recommended to use a material with an adsorptive capacity of 20 to 100 mg/g. As far as the base material is transparent, its use is not defined and for example, organic film or sheet of polyethyleneterephthalate, polyester or diacetate and various types of glass are used.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to recording materials, particularly transparent recording materials that have high color development properties (and are ideal for use in overhead projectors, etc., which can record without color unevenness). This is related.

[Prior Art] In recent years, overhead projectors are increasingly being used in place of conventional slide projectors for presentations at various academic conferences, conferences, and the like. or,
In the field of printing, transparent printed matter is required for various publications, packaging, and other uses.

Printing on these transparent sheets requires special consideration in terms of printing speed and drying compared to printing on ordinary paper because the sheet itself, which is the base material, has no absorbency.

In addition, in order to obtain small printouts such as sheets for overhead projectors, the method of editing the original using a computer or word processor and printing it with a printer is widely used, and the printer is capable of printing in full color. The inkjet method is attracting attention because it is easy.

[Problems to be solved by the invention] However, when conventional inkjet methods are used for transparent sheets, a large amount of ink is handled, so printing on transparent sheets with poor absorbency is only possible in extremely low-quality cases. It was possible, but full color was almost impossible.

On the other hand, it is conceivable to provide an ink absorbing layer such as a silica layer provided on the paper surface on a transparent substrate, but in this case, generally light scattering occurs, transparency is impaired, and the image is It has the disadvantage of becoming whitish.

[Means for Solving the Problems] The present inventor has eliminated these drawbacks, provided an ink absorbing layer that can be used in full color, and has developed a method that does not impede the transparency of the base material and prevent the image from becoming whitish. As a result of various studies and examinations with the aim of obtaining a recording sheet that is suitable for recording, it has been found that the above object can be achieved by selecting the surface smoothness of the ink-receiving layer provided on the transparent substrate within a specific range. Ta.

Thus, the present invention provides a recording material characterized in that an ink-receiving layer having a surface roughness of 0.05 μm or less is provided on a transparent substrate.

In the present invention, the ten-point average roughness of the ink-receiving layer is 0.0.
It is necessary that the thickness be 5μ or less. If the ten-point average roughness does not satisfy the above range, it is unsuitable because light scattering occurs, transparency is impaired, and the image becomes whitish.

Note that the ten-point average roughness is defined in JIS BO601, and was determined as follows.

Three-dimensional length-measuring scanning electron microscope (ESA manufactured by Elionix)
-3000) to observe the unevenness of the coated surface at a magnification of 5.
000 times), and the ten-point average roughness (JIS BO601) was calculated from the obtained profile. The means for imparting smoothness to the ink-receiving layer is not particularly limited, and any appropriate means such as roll press or flat plate press using a flat plate may be employed.

As the material used for the ink receiving layer, porous bodies such as silica and alumina can be used as appropriate, but it is particularly preferable to use a substance having an adsorption capacity of 20 to 100 mg/g.

Note that the adsorption capacity used in the present invention is defined as follows.

Add 1 g of powder of a material that will become an ink receiving layer with an average particle size of 15 μm to 100 cc of water at room temperature, and add F to this while stirring.
1 c of an aqueous solution containing 2% by weight of ood Black 2
The powder is added dropwise at a rate of c/min, and the point at which the liquid begins to be colored is defined as the dye solid content (mg/g) adsorbed in the powder.

A preferable example of the substance having an adsorption capacity of 20 to 100 mg/g is pseudo-boehmite.

As such pseudo-boehmite, commercially available product name "
An alumina sol containing 7% by weight in terms of Al2O3 solid content, such as Cataloid AS-3j, was diluted 100 times with pure water, and this was dropped onto a hydrophilized collodion membrane and dried. In this case, particularly high image quality can be obtained by using an alumina sol that forms an alumina hydrate aggregate of hair-like bundles oriented in a certain direction.

In addition to the above physical properties, if the total volume of pores with a radius of 100 to less than 1000 is adopted as 0.2 to 1.0 cc/g or less, transparency becomes even better; If the total volume of pores having 10 to less than 40 pores is set to 0.2 to 1.0 cc/g, even higher image quality can be obtained.

In the present invention, in addition to these physical properties, the most preferable high image quality can be obtained by using a substance having the above-mentioned adsorption ability for the ink receiving layer, particularly pseudo-boehmite, particularly the above-mentioned specific pseudo-boehmite.

The transparent substrate used in the present invention is not particularly limited as long as it is transparent, but for example, organic films and sheets such as polyethylene terephthalate, polyester, and diacetate, various types of glasses, and the like can be used.

When these substrates are used, they can be subjected to surface treatment such as corona discharge treatment or provided with a precoat layer in order to improve adhesion with the ink-receiving layer. The thickness of the ink-receiving layer is appropriately selected depending on the amount of ink used for printing, but it is generally appropriate to adopt a thickness of about 0.5 to 20 .mu.m.

If the layer thickness deviates from the above range, the color development may become unstable or impaired, which is not preferable. As a means of providing an ink-receiving layer on a transparent substrate, a mixed slurry of the material constituting the layer and a binder is coated onto the substrate using various coaters such as a roll coater, an air knife coater, a blade coater, a rod coater, and a bar coater. However, drying methods are mainly used.

The surface of the ink-receptive layer immediately after being applied onto the substrate using such coaters is smooth, but when it is dried as is (the surface becomes irregularly uneven during the process), In the invention, after or immediately before drying the ink-receiving layer, the above-described roll press or flat plate pressing is performed to smooth the layer.At this time, the pressing pressure is strictly determined by the material of the ink-receiving layer used. However, it is generally appropriate to adopt a linear pressure of about 10 to 40 kg/am.

If the press pressure is too low, smoothness cannot be obtained, and if the press pressure is too high, the pores may be crushed, which is not preferable.

As a binder, starch, its modified product, P
Organic substances such as VA or modified products thereof, SBR latex, hydroxycellulose, and polyvinylpyrrolidone can be used.

In addition, if the amount used is too small, the strength of the receptor layer will be insufficient, and if it is too large, the ink absorbability will be inhibited, so it is not preferable (generally, the amount of pseudoboehmite is 10 to 50
It is appropriate to adopt approximately % by weight.

The pore size distribution in the present invention is measured using the nitrogen adsorption/desorption method (
The test was carried out using Omnisorb 100 (manufactured by Omicron Technology).

[Example] Example-1 Alumina Sol 100 (manufactured by 8 Sankagaku Co., Ltd.) 5 parts (solid content),
Polyvinyl alcohol PVA117 (manufactured by Kuraray) 1
A coating liquid of 10% solids consisting of 100% (same) and water was prepared and applied to a polyethylene terephthalate film (Toshisha WIJ100μ) using a bar coater so that the dry film thickness was 5μ, and dried. A recording sheet was obtained.

The ten-point average roughness of the surface of the coating layer of the obtained sheet was 0.05.
It was u.

Example 2 Pseudo-boehmite silcataloid AS having an adsorption capacity of 80 mg/g was used in place of alumina sol 100 in Example 1.
-3 (Catalyst Kasei) was used to prepare a sheet, which was then subjected to a test calender roll (Tester Sangyo) (linear pressure 10 kg/cm ), and the surface roughness was 0.03.
Finished to be μ.

In addition, the volume of pores with a radius of 40 to 100 pores in this sheet is 0.23 m1/g, and the volume of pores with a radius of 100 to 1000 pores is 0.02 m1/g, with 10 to less than 40 pores. The pore volume was 0.5+nl/g.

Comparative Example 1 A sheet was created using pseudo-boehmite silcataloid AS-3 (Catalyst Kasei) in place of alumina sol 100 in Example 1. The surface roughness of this sheet is 0.
It was 50μ.

Comparative Example 2 The polyethylene terephthalate film (manufactured by Toshi Co., Ltd., 100μ) used as the base film in Example 1 was used as a sheet in Comparative Example 2.

Test patterns were printed on the films of Examples 1 and 2 and Comparative Examples 1 and 2 using a color image jet printer (inkjet method) LO-735 manufactured by Sharp Corporation, and the resolution and sharpness thereof were evaluated. In addition, offset ink (
Moroboshi ink, sumi) was printed, and the time it took for the problem to occur was measured even when high-quality paper was applied to the printed surface and pressure was applied.

These results were as follows.

Claims (1)

[Scope of Claims] 1. A recording material comprising an ink-receiving layer having a surface roughness of 0.05 μm or less on a transparent substrate. 2. A recording material according to claim (1), wherein the ink-receiving layer whose surface has a ten-point average roughness of 0.05 μm or less is a substance having an adsorption capacity of 20 to 100 mg/g. 3. The recording material according to claim 2, wherein the substance having an adsorption capacity of 20 to 100 mg/g is pseudoboehmite. 4. Pseudo-boehmite is 7 in terms of Al_2O_3 solid content
When an alumina sol containing % by weight is diluted 100 times with pure water and dropped onto a hydrophilized collodion film and dried, an aggregate of hair-like bundled alumina hydrates oriented in a certain direction is formed. The recording material according to claim (3), which is an alumina sol having the following properties. 5. A claim in which the ink receiving layer has a surface with a ten-point average roughness of 0.05 μ or less, and the total volume of pores having a radius of 40 to 100 Å is 0.1 or more and less than 0.4 cc/g. Recording materials in item (1) or (2). 6. The ink receiving layer has a surface with a ten-point average roughness of 0.05 μ or less, and the total volume of pores with a radius of 40 to less than 100 Å is 0.1 or more and less than 0.4 cc/g, and The total volume of pores with 100-1000 Å is 0.1 cc
The recording material according to claim (1), which is /g. 7. The ink-receiving layer with a surface ten-point average roughness of 0.05 μ or less has a total volume of pores with a radius of 10 to less than 40 Å, a total volume of 0.2 to less than 1.0 cc/g, and a radius of 100 to 1000 Å.
The recording material according to claim 1, wherein the total volume of pores having Å is 0.1 cc/g or less. 8. The recording material according to claim (5), (6), or (7), wherein the ink-receiving layer whose surface has a ten-point average roughness of 0.05 μ or less is a material having an adsorption capacity of 20 to 100 mg/g. material. 9. The recording material according to claim 8, wherein the substance having an adsorption capacity of 20 to 100 mg/g is pseudoboehmite. 10. When an alumina sol containing 7% by weight of pseudo-boehmite in terms of Al_2O_3 solid content is diluted 100 times with pure water and dropped onto a hydrophilized collodion film and dried, The recording material according to claim 9, which is an alumina sol which forms an aggregate of oriented hair-like bundles of alumina hydrate.