JPH03275378A - Printing sheet - Google Patents

Abstract

PURPOSE:To improve ink absorption properties by a method wherein a printing sheet is produced by providing a porous ink accepting layer on a substrate, and said layer is made of a pseudo-boehmite layer with voids of a specific radius and has a void volume of a specific percent of a total volume. CONSTITUTION:On a substrate, such as an organic film, a slurry mixed with a pseudo-boehmite and a binder is applied using a roll coater or the like and dried to form a porous ink accepting layer. Then, a printing sheet is obtained. The ink accepting layer on the obtained printing sheet has voids of a radius of substantially 10-100Angstrom and has a 10-30Angstrom radius void volume of 70% or more of a total volume. In addition to the aforesaid physical properties, it is preferable that a total 10-30Angstrom radius void volume is 0.25-0.70cc/g in the ink accepting layer. Furthermore, the ink accepting layer is preferably the order of 1-10mum in thickness.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a printing sheet.

[Background Art] In recent years, in the field of printing, full-color and transparent printing has been promoted for various publications, packaging, prepaid cards, etc., and higher image quality is required.

In general, many of these sheets do not have a particular ink fixing layer, and printing on these sheets requires special filtration in terms of printing speed and drying because the sheets have poor ink absorption.

[Problems to be Solved by the Invention] In addition to high-speed printing properties, these conventional printing sheets have a layer where the ink is fixed by drying on the sheet,
Not only does it have poor high-speed printing properties, but it also has the disadvantage that it does not necessarily produce clear colors.

Furthermore, when the sheet is transparent, the use of space powder after printing, which is commonly done in offset printing, may impair transparency, and is therefore undesirable.

[Means for Solving the Problems] As a result of various studies and examinations in order to solve the above-mentioned problems, the present inventor has found that an ink-receiving layer is provided on a base material using an alumina sol that can have a specific pore structure. It has been found that the above object can be achieved.

Thus, the present invention provides a printing sheet in which a porous ink-receiving layer is provided on a base material, in which the ink-receiving layer mainly consists of a pseudo-boehmite layer, and the core layer has a radius of substantially 10 to 10
The present invention provides a printing sheet characterized in that it has 0 pores and the pore volume occupied by pores with a radius of 10 to 30 pores is 70% or more of the total volume.

As the base material used in the present invention, in addition to transparent materials such as organic films and sheets such as polyethylene terephthalate, polyester, and diacetate, and various glasses, opaque materials such as paper and metal can be appropriately used.

Further, the thickness of the base material is selected depending on the purpose and is not particularly limited. When these base materials are used, they may be subjected to surface treatment such as corona discharge treatment or provided with a precoat layer in order to improve adhesion to the ink-receiving layer.

The ink receiving layer in the present invention has a radius of substantially 10 to 10
It is necessary to have 0 pores and the pore volume occupied by pores with a radius of 10 to 30 pores is 70% or more of the total volume. If the radius and total volume deviate from the above ranges, light scattering occurs, the printed image becomes whitish, and transparency is impaired in the case of a transparent sheet, which is unsuitable.

Desirably, in addition to these physical properties, the radius of the ink receiving layer 1
The total volume of pores with 0-30 people is 0.25-0.70
cc/g is preferred. By doing so, it is possible to obtain a clear image with sufficient ink absorbency, and the transparency of the transparent sheet is not impaired. In the present invention, pseudoboehmite is effective in forming an ink receiving layer having these physical properties, and sufficient absorbency and transparency can be obtained.

The thickness of the ink-receiving layer is appropriately selected depending on the amount of ink used for printing and printing, but it is generally appropriate to adopt a thickness of about 1 to 10 μm. If the layer thickness deviates from the above range, the absorbency may become poor or transparency may be impaired, which is not preferable.

The main method for providing an ink-receiving layer on a substrate is to apply a mixed slurry of pseudo-boehmite and a binder onto the substrate using various coaters such as a roll coater, an air knife coater, a blade coater, or a bar coater, and then dry it. used.

Use of a sol of pseudo-boehmite is desirable because a preferred ink-receiving layer can be easily obtained.

As the binder, it is preferable to use PVA or a modified product thereof. In addition, if the amount used is too small, the strength of the receptor layer will be insufficient, while if it is too large, it will impede the ink absorption, which is not preferable (in general, pseudo-boehmite's 7
It is appropriate to employ about 30% 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).

Examples will be shown below, and although the printing sheet according to the present invention is particularly useful for offset printing, it is not limited thereto. In addition, although transparent printed matter is particularly useful, opaque printed matter is also useful in that it takes advantage of the base material.

[Example] The printing sheets obtained in the Examples were evaluated by the following method.

■ Absorption: Solid printing (reflective color density 1
．． Immediately after (20 seconds later), high-quality paper was applied to the surface to be printed, pressure was applied using a printability tester, and the color density of the ink transferred to the high-quality paper was measured using a reflective color densitometer. (The measurement results indicate that the smaller the number, the harder it is to transfer and the better the absorbency of the printing sheet.

■Transparency: Haze was measured according to JIS K-7105.

Example 1 8 parts (solid content) of pseudoboehmite sol obtained by hydrolyzing and peptizing impropoxide, polyvinyl alcohol PVA1
17 (manufactured by Kuraray Co., Ltd.) (solid part) and water with a solids content of approximately 10 wt% was prepared, and a polyethylene terephthalate film as a base material (OC type, manufactured by Ontaisha Co., Ltd.) was prepared.
100 μm thick) using a bar coater so that the film thickness after drying was 5 μm, and dried to obtain a printing sheet.

Example 2 A printing sheet was obtained in the same manner as in Example 1 except that pseudo-boehmite sol AS-2 (manufactured by Catalysts Kasei Co., Ltd.) was used.

Example 3 A printing sheet was obtained in the same manner as in Example 1 except that pseudo-boehmite sol AS-520 (manufactured by Nissan Chemical Industries, Ltd.) was used.

Example 4 A printing sheet was obtained in the same manner as in Example 1 except that an opaque film (white polyethylene terephthalate) was used as the base material.

Example 5 A printing sheet was obtained in the same manner as in Example 2 except that art paper was used as the base material.

Table 1 shows the physical properties and evaluation results of the ink receiving layer of these printing sheets.

Claims (1)

[Scope of Claims] 1. In a printing sheet having a porous ink-receiving layer provided on a base material, the ink-receiving layer mainly consists of a pseudo-boehmite layer, and the layer substantially has pores with a radius of 10 to 100 Å. A printing sheet 2 characterized in that the pore volume occupied by the pores with a radius of 10 to 30 Å is 70% or more of the total volume, and the total volume of the pores with a radius of 10 to 30 Å in the ink receiving layer. Claim (1) is 0.25 to 0.70 cc/g.
printing sheet