JPH03281384A - Alumina sol for recording medium - Google Patents

Abstract

PURPOSE:To improve the selective adsorbability of a dye by preparing a sol forming a columnar boehmite aggregate whose particle shape has a specific aspect ratio in a state of being dripped on a collodion membrane made hydrophilic by diluting collodion to specific concn. of water and dried. CONSTITUTION:An alumina sol for a recording medium forming a bundle-like aggregate oriented in a fixed direction of boehmite whose sol particle has a columnar shape having an aspect ratio of 3 or less in a state of being dripped on a collodion membrane made hydrophilic by diluting collodion to 0.01 - 0.1% on a solid wt. basis by water and dried is prepared. This alumina sol is pref. dried at temp. equal to or less than the heat-resistant temp. of the collodion membrane and usually dried at room temp. and the shape of the alumina sol particle on the collodion membrane is observed using a transmission type electron microscope. Since the obtained alumina sol selectively adsorbs a dye with respect to the solvent in ink, printed matter having a sharp hue is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an alumina sol for recording media.

(Prior Art) In recent years, various printing technologies have been developed, and the demand for high-speed printing or high-quality printed matter is increasing. Generally, high-quality printed matter requires a recording medium that can sufficiently support the pigment in the ink. Hitherto, as such recording media, for example, talc and porous silica particles are known.

(Problems to be Solved by the Invention) However, talc has poor ink absorbency and can only be used for low-quality printing. Furthermore, although silica has ink absorption properties, it has the disadvantage that it carries a large amount of solvent along with the pigments that make up the ink, making it difficult to obtain clear colors.

(Means for Solving the Problems) The present invention is an alumina sol whose sol particles are made of boehmite, which is diluted with water to a solid content of 0.01 to 0.1% by weight, and dropped onto a hydrophilized collodion film. The present invention provides an alumina sol for recording media, characterized in that, in a dried state, the particle shape is columnar with an aspect ratio of 3 or less, and forms bundle-like aggregates oriented in a certain direction.

Traditionally, alumina sol has been utilized in many fields such as the textile industry, ceramics and refractories industry, cosmetics, and petrochemistry (catalyst carrier). The sol particles in the Ano 1 mina sol include
There are amorphous and normal quality (boehmite) types, and particle shapes such as rods, feathers, fibers, and plates are known, but alumina sol for use in recording media has not yet been produced. unknown.

The present inventors have discovered that an alumina sol of boehmite particles having a specific particle shape and agglomerated shape is particularly excellent as a rust recording medium, and has developed the present invention. Here, the particle shape of the alumina sol is observed as follows.

First, alumina sol is mixed with water to form a solid compound (1, (11~0.
Dilute to 1% by weight. Next, the diluted alumina sol is dropped onto the hydrophilized collodion film and dried. The drying method is preferably below the heat resistant temperature of the collodion membrane,
Usually dried at room temperature. Then, the shape of the alumina sol particles on the collodion film is observed using a transmission electron microscope.

When the alumina sol of the present invention is observed as shown in Part 2 above, the particle shape of the sol is columnar with an aspect ratio of 3 or less, and forms bundle-like aggregates oriented in a certain direction. Therefore, when used as a recording medium, a recording medium layer consisting of pores formed by columnar particles and pores formed by bundle-like aggregates is constructed, and ink is sufficiently supported.

It is more preferable that the particle shape of the sol is columnar with an aspect ratio of 1.1 to 2.

Furthermore, since the alumina sol of the present invention selectively adsorbs the dye to the solvent in the ink, printed matter with vivid colors can be obtained.

In the present invention, the sol particles need to be boehmite. If the sol particles are amorphous, they are unsuitable for use in recording media because they have poor ink absorbency and dye carrying ability.

(Example) Example 1 One aluminum bullion cataloid AS-3 (manufactured by Catalysts Kasei Co., Ltd.)
When dried at 40°C, the solid content was 9% by weight.

This alumina sol was diluted 150 times with pure water, dropped onto a hydrophilized collodion membrane, dried at room temperature, and observed with a transmission electron microscope (100,000 times magnification). The particle shape of the sol was columnar with an aspect ratio of 1.1 to 2, and formed bundle-like aggregates oriented in a certain direction. Furthermore, when the dried alumina sol was examined by X-ray diffraction, it showed a boehmite diffraction peak.

13.5 g of 10% polyvinyl alcohol solution (PVA manufactured by Kuraray Co., Ltd., 17) in 100 g of this alumina sol
A coating solution was prepared by mixing the following. This coating solution was applied to a polyethylene terephthalate film (OC type, 10,100 μm thick, manufactured by Kijinsha Co., Ltd.) as a base material using a bar coater so that the film thickness after drying was 5 μm, and dried to obtain a recording sheet. Ta.

On this recording sheet, print 1 c+e in black using a Sharp color image jet printer 10-735.
A pattern of x 1 cm was printed. This sheet was backed with white paper, and the reflective color density of black was measured using a Sakura densitometer PDA45. Furthermore, the resolution was visually evaluated based on the degree of blurring of the pattern on this sheet in four grades from O to 3 (O1: worst, 3: best). The reflected color density was 1.18 and the resolution was 3.

Comparative Example A recording sheet was obtained in the same manner as in Example 1, except that Alumina Sol 100 (manufactured by Nissan Chemical Co., Ltd.) was used instead of AS-3 in Example 1. Example 1 following alumina sol 100
When the particle shape was observed in the same manner as above, amorphous particles with no particular orientation were observed. Moreover, this particle was amorphous.

When this recording sheet was evaluated in the same manner as in Example 1, the reflected color density was 1.02 and the resolution was 0.

Example 2 The recording sheet obtained in Example 1 was subjected to solid printing (solid printing) using an offset ink (New Bloast G; cyan, manufactured by Dainippon Ink Co., Ltd.) using a printing suitability tester RI-2 model (Akashi Seisaku Kai). Reflection color density 1.55) and 20
After a few seconds, a piece of wood-free paper was applied to the surface to be printed, and pressure was applied using a printability tester, and the color density of the ink transferred to the wood-free paper side was measured using a reflective color densitometer. As a result, the transferred color density is
It was 0.01. For comparison, a similar test was conducted on art paper, and the transferred color density was 0.22.

As for the transferred color density, the smaller the value, the better the absorbency of the transfer. Therefore, it can be seen that the recording sheet of the example exhibits printability superior to art paper.

(Effect of the invention) When the alumina sol of the present invention is used as a recording medium,
It has good ink absorption and can produce high-quality printed matter at high speed. Because it selectively supports the pigment in the ink, vivid colors can be obtained.

Claims (1)

[Claims] (1) The sol particles are an alumina sol made of boehmite, diluted with water to a solid content of 0.01 to 0.1% by weight,
An alumina sol for a recording medium, characterized in that when dropped onto a hydrophilized collodion film and dried, the particle shape forms a bundle-like aggregate having a columnar shape with an aspect ratio of 3 or less and oriented in a certain direction.