JP2936631B2 - Printing sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a printing sheet.

[Prior Art] In recent years, in the field of printing, full color and transparency have been developed for various publications, packaging, prepaid cards, and the like, and high image quality has been demanded.

In general, many of these sheets do not particularly have an ink fixing layer, and printing on these sheets requires special considerations in terms of printing speed and drying due to poor ink absorbency of the sheets.

[Problems to be Solved by the Invention] Furthermore, since these conventional printing sheets do not have a layer in which the ink is fixed by drying on the sheet, not only the high-speed printability is poor, but also a clear color development is not necessarily achieved. Has no disadvantages.

Further, when the sheet is a transparent body, use of a space powder after printing, which is generally performed in offset printing, may impair transparency, which is not preferable.

[Means for Solving the Problems] The present inventor has conducted various studies and studies to solve the above-mentioned problems, and as a result, has achieved the above object by providing an ink receiving layer having a specific pore structure on a substrate. I found that I could do it.

The present invention provides a printing sheet in which a porous ink receiving layer is provided on a substrate, wherein the ink receiving layer is mainly composed of pseudo-boehmite, and the pore size distribution of the ink receiving layer is determined by a nitrogen adsorption / desorption method. Has a radius of 10 to 10
An object of the present invention is to provide a printing sheet characterized in that a pore volume present in a range of 0 ° and occupied by pores having a radius of 10 to 30 ° is 70% or more of the total pore volume.

As the substrate used in the present invention, for example, an organic film or sheet such as polyester or diacetate such as polyethylene terephthalate, a transparent body such as various glasses, and an opaque body such as paper or metal can be appropriately used. .

Further, the thickness of the substrate is selected depending on the purpose, and is not particularly limited. These substrates may be subjected to a surface treatment such as a corona discharge treatment or a pre-coat layer in order to improve the adhesiveness with the ink receiving layer when used.

In the ink receiving layer according to the invention, the pores have a radius of substantially 10 to 10 in the measurement of the pore size distribution by the nitrogen adsorption / desorption method.
It is necessary that the pore volume existing in the range of 0 ° and occupied by pores having a radius of 10 to 30 ° is 70% or more of the total pore volume. If the pore distribution deviates from the above range, light is scattered, the printed image becomes whitish, and the transparency of a transparent sheet is impaired.

Desirably, in addition to these physical properties, in the pore size distribution of the ink receiving layer by the nitrogen adsorption / desorption method, a radius of 10
Preferably, the pore volume occupied by pores of up to 30 ° is 0.25 to 0.70 cc / g. By doing so, a sufficient image can be obtained with sufficient ink absorbency, and the transparency of the transparent sheet is not impaired. In the present invention, since the ink receiving layer having these physical properties is mainly composed of pseudo-boehmite, sufficient absorption 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 employ about 1 to 10 μm. If the layer thickness deviates from the above range, the absorbability may be poor, or the transparency may be impaired.

As a means for providing the ink receiving layer on the substrate, a means of applying a mixed slurry of pseudo-boehmite and a binder on the substrate by various coaters such as a roll coater, an air knife coater, a blade coater, and a bar coater, and then drying is mainly used. Can be

Pseudo-boehmite in the ink receiving layer is desirable because it is possible to easily obtain an ink receiving layer that is preferably formed using the sol.

It is preferable to use PVA or a modified product thereof as the binder. On the other hand, if the amount is too small, the strength of the receiving layer becomes insufficient. On the other hand, if the amount is too large, the ink absorbability is impaired, which is not preferable. Generally, about 7 to 30% by weight of pseudo-boehmite is used. Appropriate.

The pore size distribution in the present invention was measured by a nitrogen adsorption / desorption method (Omni Soap 100 manufactured by Omicron Technology Co., Ltd.).

Examples will be described below. The printing sheet according to the present invention is particularly useful for offset printing, but is not limited thereto. It is also particularly useful for transparent prints,
It is also useful for opaque printed materials in terms of utilizing the base material.

[Examples] The printing sheets obtained in the examples were evaluated by the following methods.

Absorbency: Solid printing (reflection color density) using offset ink [(Newprous-G: Cyan (manufactured by Dainippon Ink)) using printability tester RI-2 type (manufactured by Meiji Seisakusho)
Immediately after that (20 seconds), high-quality paper was applied to the surface to be printed, pressure was applied by a printability tester, and the color density of the ink transferred to the high-quality paper was measured by a reflection color densitometer. The measurement results show that the smaller the numerical value, the less the transfer is, and the better the absorbability of the printing sheet.

Transparency: Haze was measured according to JIS K7105.

Example 1 8 parts (solid content) of pseudo-boehmite sol obtained by hydrolyzing and peptizing isopropoxide, polyvinyl alcohol PVA1
17 (manufactured by Kuraray Co., Ltd.) and a coating solution of about 10 wt% solids composed of water were prepared, and a polyethylene terephthalate film (OC type, manufactured by Teijin Limited, thickness: 100 wt.
μm) was applied by 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 Catalyst 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 a substrate.

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 layers of these printing sheets. In Table 1, the radius is 10-30Å
Is the ratio of the pore volume occupied by pores having a radius of 10 to 30 ° to the total pore volume.

Claims (2)

(57) [Claims] In a printing sheet having a porous ink receiving layer provided on a base material, the ink receiving layer is mainly composed of pseudo-boehmite, and the fine pore diameter distribution of the ink receiving layer is determined by a nitrogen adsorption / desorption method. The hole has a radius of substantially 10-10
A printing sheet, wherein the pore volume is in the range of 0 mm and the pore volume occupied by pores having a radius of 10 to 30 mm is 70% or more of the total pore volume. 2. The printing sheet according to claim 1, wherein a pore volume occupied by pores having a radius of 10 to 30 ° is 0.25 to 0.70 cc / g in a pore diameter distribution of the ink receiving layer by a nitrogen adsorption / desorption method. .