JPH09142014A - Recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent slip properties without damaging printing quality by providing a porous ink receiving layer on one surface of a base material sheet and forming unevenness on the other surface thereof by a laser marker. SOLUTION: Unevenness is formed on the rear surface of a base material sheet by a laser marker. It is pref. to form regular patterns because slip properties between recording sheets become uniform but irregular patterns may be formed. As the regular patterns, geometric patterns such as checkered patterns, polka-dot patterns or checked patterns or patterns wherein company names or commodity names or logomarks of them are regularly arranged are designated. Since unevenness is formed on the rear surface of the base material sheet by the laser marker, blocking between recording sheets is suppressed and, as a result, slip properties between sheets are enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording sheet, particularly a recording sheet suitable for an ink jet printer.

[0002]

2. Description of the Related Art With the spread of full-color printers in recent years, various recording media such as film, paper and cloth have been adopted according to various recording systems. At the same time,
There has been a demand for improvement in the transportability of recording media, especially film-like sheets, which are compatible with an automatic paper feeding mechanism for continuously transporting a plurality of sheets.

Ink jet printers have become rapidly popular in recent years because they are easy to produce in full color and have low printing noise. In the inkjet method, ink droplets are ejected from a nozzle toward a recording medium at high speed, and the ink contains a large amount of solvent. Therefore, it is necessary for the recording sheet to absorb the ink promptly, and there is known a recording sheet in which a porous ink receiving layer is provided on a substrate.

[0004]

A recording sheet having a porous ink-receiving layer 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 copying machine is difficult. The present invention, without impairing the print quality,
An object is to provide a recording sheet having excellent slipperiness.

[0005]

The present invention provides a recording sheet having a porous ink receiving layer on one surface of a substrate sheet and having irregularities formed on the other surface by a laser marker.

According to the present invention, the surface of the recording sheet on which the ink receiving layer is not formed (hereinafter referred to as the back surface) has the unevenness formed by the laser marker, so that the blocking between the recording sheets is suppressed, and as a result, Sliding property between sheets is improved. In the present invention, the laser marker means a machine having a function of printing by irradiating an object with a laser height.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The material of the base sheet is not particularly limited, and various materials can be used. Specifically, various plastic sheets such as polyester resin such as polyethylene terephthalate, polycarbonate resin, fluorine resin such as ETFE, and various papers can be preferably used. For example, when an opaque plastic film containing a white or other color pigment is used, a recording sheet having good gloss and capable of recording with high color density can be obtained. Further, the base sheet may be subjected to corona discharge treatment or undercoating for the purpose of improving the adhesive strength of the ink receiving layer.

When the irregularities formed by the laser marker on the back surface of the base sheet are formed in a regular pattern, it is preferable because the slipperiness between the recording sheets becomes uniform, but the irregular pattern is formed. But it's okay. Examples of the regular pattern include geometric patterns such as a grid pattern, a polka dot pattern, and a checkered pattern, or a pattern in which company names, product names, or their logos are regularly arranged. Without being limited to these, various other designs can be adopted. The height difference of the irregularities is preferably about 0.1 to 50 μm.

The ink receiving layer is preferably a porous layer containing inorganic particles, and particularly preferably a structure in which inorganic particles are bound with an organic binder. When alumina or alumina hydrate is contained as the inorganic particles, it is preferable in terms of excellent ink absorbability and dye fixing, and particularly boehmite (compositional formula Al
₂ O ₃ · nH ₂ O, n = 1 to 1.5) is preferable.

The ink receiving layer has pores whose pore structure has a radius of 1 to 15 nm and has a pore volume of 0.3.
It is preferable for it to be 1.0 cc / g because it has sufficient absorbability and high transparency. When the transparency of the ink receiving layer is high, the coloring of the dye is good when the ink is absorbed. The pore radius distribution is measured by the nitrogen adsorption method.

The thickness of the ink receiving layer is 0.1 to 100 μm.
m is preferably in the range. If the thickness of the ink receiving layer is less than 0.1 μm, the fixability and absorptivity of the dye will be insufficient, and clear and high color density recording may not be possible, which is not preferable. The thickness of the ink receiving layer is 100
When it exceeds μm, the mechanical strength of the ink receiving layer may be lowered, or the transparency may be reduced to lower the color density of the recorded matter, which is not preferable. The more preferable thickness of the ink receiving layer is 5 to 50 μm.

As a means for providing an ink receiving layer on a substrate sheet, for example, a binder is 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, modified products thereof, polyvinyl alcohol and modified products thereof, SBR latex, NBR latex, carboxymethyl cellulose, hydroxymethyl cellulose, polyvinyl pyrrolidone and the like can be used. The amount of the binder used is preferably about 5 to 50% by weight of the inorganic particles. If the amount of the binder used is less than 5% by weight, the strength of the ink receiving layer may be insufficient.
If it exceeds 0% by weight, the ink absorbency may be insufficient, which is not preferable.

It is preferable that the ink receiving layer has a silica gel layer formed on the above boehmite porous layer because scratch resistance is improved as compared with the case where the boehmite porous layer is used alone. The silica gel layer can be firmly adhered to the surface of the sheet by preferably dispersing silica sol in a binder solution and then coating and drying. 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.

As the binder, the same binders as described above can be used, but it is particularly preferable to use a silicon-containing polymer such as silicon-containing polyvinyl alcohol. The amount of binder used depends on the solid content (Si
The amount is preferably 1 to 30% by weight based on O ₂ .

The thickness of this silica gel layer is 0.1 to 30.
It is preferably about μm. Thickness of silica gel layer is 0.1μm
If it is less than the above range, the effect of improving the scratch resistance is insufficient, which is not preferable. When the thickness of the silica gel layer exceeds 30 μm, the transparency of the ink receiving layer may be impaired, which is not preferable.

[0017]

[Examples] A laser marker (ML-9000 manufactured by Keyence Corporation) was used on one side of a polyethylene terephthalate film (white film, 100 μm thick), and one side of a character having a size of 5 mm × 5 mm (A4 Writing about 100 pieces for each size) to form irregularities. The height difference of the unevenness was about 5 μm.

Alumina sol 1 having a solid content of 18% by weight synthesized by the hydrolysis / peptization method of aluminum isopropoxide
00g and polyvinyl alcohol 6.2 weight% aqueous solution 32
g was mixed to prepare a coating liquid. This coating liquid was applied to the surface of the above-mentioned base material sheet on which the irregularities were not formed by using a die coater and dried. Coating amount is 30 after drying
g / cm ² . After drying, it was further heat-treated at 140 ° C. to form a boehmite porous layer.

On this porous boehmite layer, silica sol having a primary particle size in the range of 20 to 30 nm and silicon-containing polyvinyl alcohol (Kuraray Co., Ltd., trade name R-
Polymer R-1130) and a solid content of 5% by weight (R
A coating liquid (-1130 / SiO ₂ = 0.1 (weight ratio)) was applied by a bar coater so that the coating thickness after drying was 3 μm, and dried. After drying, it was further heat treated at 140 ° C. to form a silica gel layer to obtain a recording sheet.

This recording sheet was cut into A4 size sheets,
100 sheets were stacked and loaded in a full-color inkjet printer having an automatic paper feeding mechanism, and a printing test was continuously performed. A clear full-color image with high color density could be formed on the ink receiving layer. Further, the recording sheets were not jammed, and the sheets could be fed smoothly one by one.

[0021]

The recording sheet of the present invention has a high ink absorbency and a high dye adsorbability, and has a good slip property between the recording sheets and an excellent handleability. Especially suitable for automatic paper feeding in printers and copiers.

Claims (1)

[Claims] 1. A recording sheet having a porous ink receiving layer on one surface of a substrate sheet and having irregularities formed on the other surface by a laser marker.