JPH082093A - Recording sheet and production thereof - Google Patents

Abstract

PURPOSE:To impart proper slip properties to a recording sheet to facilitate the continuous feed of the recording sheet. CONSTITUTION:An ink jet printer recording sheet is obtained by providing a pseudo boehmite porous layer 2 with a thickness of 1-100mum on a base material 1 and providing a silica gel layer 4 formed by dispersing and bonding silica particles 3 with a mean particle size of 0.1-30mum along with a silica sol and a binder on the upper surface of the porous layer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording sheet and its manufacturing method.

[0002]

2. Description of the Related Art In recent years, with the widespread use of electronic still cameras or computers, a hard copy technique for recording those images on a paper surface has rapidly developed. The ultimate goal of these hard copies is silver halide photography, and in particular, how to bring color reproducibility, image density, gloss, weather resistance, etc. closer to those of silver halide photography is an issue for development. As a hard copy recording method, various methods such as a sublimation type thermal transfer method, an ink jet method, an electrostatic transfer type method are known in addition to a method of directly photographing a display on which an image is displayed by a silver halide photograph.

An ink jet printer is
It has become popular rapidly in recent years because it can be easily converted into full-color and print noise is low. The inkjet method is a method of ejecting ink droplets from a nozzle toward a recording material at high speed, and the ink contains a large amount of solvent. Therefore, a recording sheet for an inkjet printer is required to quickly absorb the ink and have excellent color forming properties. For example, a recording sheet in which a porous layer of hydrated alumina is provided on a substrate is known (Japanese Patent Laid-Open No. HEI 2).
-276670, JP-A-2-27667, etc.).

[0004]

A recording sheet having a porous layer of pseudo-boehmite provided on a substrate has a strong adsorptive property between the sheets and has a poor slidability, so that it is difficult to peel the recording sheets one by one. In particular, continuous automatic paper feeding with a printer or a copier was difficult. An object of the present invention is to provide a recording sheet having excellent surface slipperiness without impairing print quality.

[0005]

DISCLOSURE OF THE INVENTION According to the present invention, a pseudo boehmite porous layer having a thickness of 1 to 100 μm is provided on a substrate, and the surface on or on which the alumina hydrate layer of the substrate is not formed. In addition, a recording sheet having silica particles having an average particle diameter of 0.1 to 30 μm dispersed and adhered thereto is provided.

In the present invention, as the alumina hydrate,
Pseudo-boehmite is preferable because it is excellent in ink absorbability and dye fixing. Pseudo-boehmite is a colloidal aggregate of boehmite crystals (compositional formula Al ₂ O ₃ .nH ₂ O, n = 1 to 1.5). The alumina hydrate porous layer preferably contains an organic binder component.

The alumina hydrate porous layer has sufficient pore structure when its pore structure is substantially composed of pores having a radius of 10 to 100Å and the pore volume is 0.3 to 1.0 cc / g. It is preferable because it has high absorbability and high transparency. At this time,
If the substrate is transparent, a transparent recording sheet that can be used for applications such as OHP (overhead projector) can be obtained. The pore radius distribution in the present invention is measured by the nitrogen adsorption method.

The thickness of the alumina hydrate porous layer is 0.1.
It is necessary to be in the range of ˜100 μm. If the thickness of the alumina hydrate porous layer is less than 0.1 μm,
It is unsuitable because the fixability and absorptivity of the dye are insufficient and clear recording with high color density cannot be performed. When the thickness of the alumina hydrate porous layer is more than 100 μm, the mechanical strength of the porous layer is lowered, or the transparency is reduced and the transparency or texture of the recorded matter is lowered, which is not suitable. is there. The more preferable thickness of the alumina hydrate porous layer is 5
˜50 μm.

Means for providing the alumina hydrate porous layer on the substrate is, for example, a binder added to alumina sol to form a slurry, and a roll coater, an air knife coater,
A method of applying using a blade coater, a rod coater, a bar coater, a comma coater, a die coater, a gravure coater, and the like, and drying can be adopted.

As the binder, organic substances such as starch and modified products thereof, polyvinyl alcohol and modified products thereof, SBR latex, NBR latex, carboxymethyl cellulose, hydroxymethyl cellulose, polyvinylpyrrolidone and the like 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 alumina hydrate porous layer may be insufficient. On the contrary, when it is more than 50% by weight, the dye adsorbability becomes insufficient. Therefore, it is not preferable.

In the present invention, the base material is not particularly limited, and various materials can be used. Specifically, various plastic sheets such as polyester resin such as polyethylene terephthalate, polycarbonate resin, and fluorine resin such as ETFE can be preferably used. In the case of an OHP recording sheet, the base material needs to be transparent, but an opaque recording sheet of the present invention can also be used. Further, for the purpose of improving the adhesive strength of the alumina hydrate layer, corona discharge treatment or undercoating can be performed.

In the present invention, silica particles are dispersed and adhered on the alumina hydrate porous layer or on the surface of the substrate on which the alumina hydrate porous layer is not formed to form surface irregularities. When the alumina hydrate layer is provided on one surface of the base material, the silica gel layer can be provided on the alumina hydrate porous layer, on the back surface thereof, or both. When the alumina hydrate porous layer is provided on both surfaces of the substrate, the silica gel layer can be provided on either or both surfaces.

The silica particles may be directly adhered to the surface of the sheet by air spraying or the like, but preferably, they can be firmly adhered to the surface of the sheet by dispersing them in a binder solution, coating and drying. As the binder, the same binder as used for forming the porous layer of pseudo-boehmite can be used, but it is particularly preferable to use a silicon-containing polymer such as silicon-containing polyvinyl alcohol.

The silica particles preferably have an average particle diameter of 0.1 to 30 μm. If it is less than 0.1 μm, the height difference of the surface irregularities is insufficient and the slipperiness cannot be exhibited, which is not preferable. If it exceeds 30 μm, the print quality may be adversely affected, which is not preferable. Any shape of silica particles can be used, but spherical shape is particularly preferable because it improves slipperiness. As the silica particles, those which are porous themselves such as spherical silica gel can be preferably used, but those which are dense themselves can also be used.

The amount of silica particles used is preferably 1 to 10 mg per 1 m ² of the sheet. The amount of silica particles used is 1m
When it is less than g / m ² , it is not preferable because sufficient slipperiness cannot be exhibited. The amount of silica particles used is 10 mg /
If it exceeds m ² , it is not preferable because it may adversely affect the printing quality.

When the silica particles are dispersed and adhered to the sheet, the silica gel layer is formed by adding a binder to silica sol to form a silica gel layer and simultaneously adhering the silica particles to improve the slipperiness and scratch resistance. Therefore, it is more preferable. As the silica sol, it is preferable to use one having an average particle diameter of 10 to 90 nm and a solid content concentration of 1 to 20% by weight.

By making the coating thickness of the silica sol smaller than the particle diameter of the silica particles, a part of the silica particles is
Concavities and convexities can be formed by protruding from the silica gel coating layer. The cross-sectional shape of the recording sheet at this time is as shown in FIG.

As the binder, the same binder as that used for forming the porous layer of pseudo-boehmite can be used, but it is particularly preferable to use a silicon-containing polymer such as silicon-containing polyvinyl alcohol. The amount of the binder used is preferably 1 to 30% by weight based on the solid content of the silica sol (converted to SiO ₂ ). If the amount of the binder used is less than 1% by weight, the mechanical strength of the silica gel layer is insufficient and the silica gel layer may peel off, which is not preferable. When the amount of the binder used exceeds 30% by weight, sufficient slipperiness cannot be exhibited, which is not preferable.

Silica particles are dispersed in this coating solution, and a silica gel layer in which silica particles are dispersed can be formed by coating on the pseudo-boehmite porous layer or the back surface of the substrate and drying. it can. The thickness of this silica gel layer is preferably about 0.1 to 30 μm. When the thickness of the silica gel layer is less than 0.1 μm, the effect of improving the slipperiness of the pseudo-boehmite layer is insufficient, which is not preferable. When the thickness of the silica gel layer is more than 30 μm, the transparency of the coating layer is impaired, which is not preferable.

[0020]

In the present invention, the mechanism by which silica particles are dispersed and adhered to the surface to improve the slipperiness is not clear, but an air layer is formed between the recording sheets due to the unevenness of the recording sheet surface. Therefore, it is considered that the adsorption between the sheets is suppressed and the contact area between the recording sheets is also reduced.

Even when the silica gel layer is formed on the alumina hydrate porous layer, the ink permeates the silica gel layer and is fixed to the alumina hydrate layer when printed by, for example, an ink jet printer. .

[0022]

【Example】

Example 1 Using an alumina sol synthesized by hydrolysis and deflocculation of aluminum isopropoxide and polyvinyl alcohol (saponification degree 98.5%, polymerization degree 2400), solid content 15% by weight (PVA / alumina sol = 0. The coating liquid of 11) was prepared. This coating solution was applied onto a polyethylene terephthalate film having a thickness of 100 μm using a die coater so that the coating thickness after drying was 30 μm, and dried to form a pseudo-boehmite layer. Furthermore, average particle diameter 12 μm
3% by weight (silica particles / P) of spherical silica (trade name: Sildex manufactured by Asahi Glass Co., Ltd.) and polyvinyl alcohol (saponification degree 98.5%, polymerization degree 500).
VA = 0.01) silica particle dispersion is coated on the pseudo-boehmite layer with a bar coater so that the average coating thickness after drying is 0.5 μm, and then heat treated at 140 ° C. to form a recording sheet. Got

Example 2 The same recording sheet as in Example 1 was manufactured except that silica particles were dispersed and adhered to the back surface.

Example 3 After a pseudo-boehmite layer having a thickness of 30 μm was formed on a polyethylene terephthalate film in the same manner as in Example 1,
Silica sol having a primary particle diameter of 35 to 55 nm and silicon-containing polyvinyl alcohol (Kuraray Co., Ltd., trade name R-
Polymer R-1130) and a solid content of 5% by weight (R
-1130 / SiO ₂ = 0.1) in the silica sol coating liquid, spherical silica having an average particle diameter of 5 μm was dispersed (spherical silica / SiO ₂ = 0.003) coating liquid on the pseudo-boehmite layer. After coating and drying with a bar coater, heat treatment was performed at 140 ° C. to obtain a recording sheet. A silica gel layer having an average coating thickness of 1.1 μm was formed on the surface of the recording sheet, and some silica particles were projected from the surface.

Comparative Example The same recording sheet was manufactured as in the recording sheet of Example 3 except that the silica sol layer was formed without adding silica particles in the silica sol coating liquid.

Printing Example 100 A4 size recording sheets each obtained in the example and 100 A4 size recording sheets of the comparative example were continuously used by using a color ink jet printer (manufactured by Hewlett Packard, product name DeskJet 505J). Printed while feeding. All the sheets of the examples were able to reliably and continuously feed all the sheets one by one, but the sheets of the comparative examples were fed into the printer at a time of two or more sheets, and the sheets were jammed. The print quality was good in both Examples and Comparative Examples and there was no particular difference.

[0027]

EFFECTS OF THE INVENTION The recording sheet of the present invention has high ink absorbency and high dye adsorbability, and has good slipperiness, and therefore has good handleability. Especially suitable for automatic paper feeding in printers and copiers. In addition, it has an effect that fingerprints and the like are hard to attach.

[Brief description of drawings]

FIG. 1 is an explanatory view showing one aspect of a recording sheet of the present invention.

[Explanation of symbols]

 1: Substrate 2: Alumina hydrate porous layer 3: Silica particles 4: Silica gel layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication D21H 19/38

Claims (4)

[Claims] 1. A substrate having a pseudo-boehmite porous layer having a thickness of 1 to 100 μm on a substrate, and having an average particle size of 0.1 on the surface of the substrate or the substrate on which the alumina hydrate layer is not formed. ~ 30 μm
A recording sheet in which the silica particles of are dispersed and adhered. 2. A pseudo-boehmite porous layer having a thickness of 1 to 100 μm is provided on a base material, and a thickness of 0.1 or more is provided on or on the back surface thereof.
A recording sheet having a silica gel layer of ˜30 μm, and a part of silica particles having an average particle size of 0.1 to 30 μm protruding from the surface of the silica gel layer. 3. A method for producing a recording sheet, wherein a pseudo-boehmite porous layer is formed on a substrate, and silica particles are applied on the back surface or the back surface of the pseudo-boehmite layer together with a binder and then dried to form surface irregularities. 4. A method for producing a recording sheet, wherein a pseudo-boehmite porous layer is formed on a base material, and silica sol and silica particles are applied onto the back surface or the back surface thereof with a binder and then dried to form surface irregularities. .