JPH09142013A - Record sheet - Google Patents

Abstract

(57) [Abstract] PROBLEM TO BE SOLVED: To impart appropriate slipperiness to a recording sheet and facilitate continuous feeding. A recording sheet having a porous ink-receiving layer on one surface of a base sheet and a regular pattern formed by printing ink on the other surface.

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, particularly film-like sheets, which are compatible with the automatic paper feeding mechanism of a printer that continuously transports 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. For this reason, the recording sheet needs to absorb the ink promptly, and a recording sheet having a porous ink receiving layer on a substrate is known.

[0004]

A recording sheet provided with a porous ink receiving layer on a base material has a strong adsorptive property between the sheets and has poor slipperiness, and thus it is difficult to peel the recording sheets one by one. Especially, continuous automatic paper feeding with a printer or a copier was difficult. An object of the present invention is to provide a recording sheet excellent in slipperiness without impairing print quality.

[0005]

SUMMARY OF THE INVENTION The present invention is a recording sheet having a porous ink-receiving layer on one surface of a substrate sheet and a film having a solidified printing ink partially adhered on the other surface. I will provide a.

According to the present invention, since the surface of the recording sheet on which the ink receiving layer is not formed (hereinafter referred to as the back surface) has a film (hereinafter referred to as the ink film) in which the printing ink is solidified, this causes the slip property between the recording sheets. improves. When the ink film is partially adhered, proper unevenness is formed on the back surface and appropriate voids are formed between the recording sheets, which also has the effect of improving slidability. Here, "partial" means that the surface of the base material sheet is
This means that there is a portion where the ink film is attached and a portion where the ink film is not attached.

[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 ink film adheres in a regular pattern on the back surface of the base sheet, it is preferable because the slipperiness between the recording sheets becomes uniform, but an irregular pattern is also possible. 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 thickness of the ink film is preferably 0.1 to 30 μm.

The color of the ink film is not particularly limited, and various colors or transparent colors can be adopted. In the case of a transparent substrate sheet, it is preferable to form a transparent ink film on the entire surface. Even if it is an opaque base sheet, if a pattern is formed on a base sheet with high translucency using a dark color ink film such as black, the pattern may be visible through the surface with the ink receiving layer. . In such a case, the color of the ink is preferably white or light gray or transparent. Alternatively, it can be dealt with by making the pattern on the back side fine.

The printing ink is adhered to the base sheet by, for example, a gravure printing method, and dried and solidified to form an ink film. Printing may be performed before or after forming the ink receiving layer on the substrate sheet.

Various kinds of printing ink can be adopted depending on the substrate sheet. The printing ink may contain a lubricant in order to improve the lubricity of the ink film surface. Suitable lubricants are, for example, polyolefin waxes and silicone waxes that are commonly used as plastic lubricants.

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 pore structures whose pores have 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 there is a risk that clear recording with high color density 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 blade coater, a rod coater, a bar coater, a comma coater, a die coater, a gravure is used. A method of applying using a coater 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 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.

In the present invention, when the ink receiving layer contains spherical or atypical resin particles, appropriate irregularities are formed on the surface of the ink receiving layer, and the slipperiness between recording sheets is further improved. The size of the spherical or amorphous resin particles is preferably 0.2 to 80 μm. As a result, it is preferable that the particles protrude from the surface of the ink receiving layer by 0.1 to 50 μm. The material of the resin particles is not particularly limited, polystyrene,
Various resins such as polymethylmethacrylate (PMMA) can be used.

The amount of resin particles added is preferably 0.005 to 5% by weight based on the inorganic particles in the ink receiving layer. If the addition amount of the resin particles is less than 0.005% by weight with respect to the inorganic particles, the transportability of the recording sheet may not be sufficiently improved, which is not preferable. If the addition amount of the resin particles exceeds 5% by weight with respect to the inorganic particles, an image having sufficient characteristics may not be obtained, which is not preferable.

A boehmite porous layer containing resin particles is formed on a base material sheet, and further, a thickness not enough to fill the irregularities formed on the boehmite porous layer on the boehmite porous layer,
It is also possible to form a silica gel layer.

[0023]

【Example】

Example 1 Polyethylene terephthalate film (white film, 1
A checkerboard pattern (mesh size: 10 mm) was gravure-printed on one surface (00 μm thick) with a gravure printing ink (color: light gray). The thickness of the obtained ink film was 0.6 μm. At this time, silicone wax was mixed in the printing ink.

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 solution, which was coated on the surface of the above film on which gravure printing was not performed using a die coater and dried. The coating amount was 30 g / cm ² after drying. After drying, it was further heat-treated at 140 ° C. to form a boehmite porous layer.

On this boehmite porous layer, silica sol having a primary particle diameter 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. As a result, a recording sheet having a boehmite porous layer and a silica gel layer as an ink receiving layer was obtained.

This recording sheet is cut into A4 size sheets, and 1
00 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. In addition, the recording sheet does not become jammed,
The paper was fed smoothly one by one.

Example 2 First, a boehmite layer and a silica gel layer were formed on a polyester film in the same manner as in Example 1 except that a grid was not printed on one surface by gravure printing. Next, a checkered pattern (size of grid: 10 mm) was gravure-printed on the entire surface of this film on which the boehmite layer and the silica gel layer were not formed, with a gravure printing ink (color: white). The thickness of the obtained ink film is 0.6 μm.
Met. At this time, a polyethylene wax was mixed in the printing ink.

When a printing test similar to that of Example 1 was conducted, a clear and high color density full-color image was similarly formed on the ink receiving layer, and the recording sheets were not clogged and smoothed sheet by sheet. I was able to feed paper.

Example 3 100 g of an alumina sol having a solid content of 18% by weight synthesized by the hydrolysis / peptization method of aluminum alkoxide and 32 g of a 6.2% by weight aqueous solution of polyvinyl alcohol were mixed, and spherical PMMA particles having a diameter of 20 μm (Sekisui Fine Chemical Co., Ltd. An alumina sol coating liquid was prepared by mixing 0.1% by weight of the company product, trade name MBX20) with the alumina sol solid content. This coating solution was applied to the surface of the same film as in Example 1 which had not been gravure printed using a die coater,
Dried. The coating amount was 30 g / cm ² after drying.
After drying, heat treatment was further performed at 140 ° C. to form a boehmite porous layer containing spherical resin particles.

On this boehmite porous layer, the same silica sol coating solution as in Example 1 was applied, dried and further heat-treated at 140 ° C. to form a 0.2 μm thick silica gel layer.

When a printing test similar to that of Example 1 was conducted, a clear and high-color density full-color image was similarly formed on the ink receiving layer, and the recording sheets were not clogged and smoothed sheet by sheet. I was able to feed paper.

[0032]

The recording sheet of the present invention has a high ink absorbency and a high dye adsorbability, and has a good slidability between the recording sheets and an excellent handleability. Especially suitable for automatic paper feeding in printers and copiers. The ink film on the back surface can provide designability.

Claims (4)

[Claims] 1. A recording sheet having a porous ink receiving layer on one surface of a base sheet and a film on which the printing ink is solidified is formed on the other surface. 2. The recording sheet according to claim 1, wherein a film in which the printing ink is solidified is partially formed on the other surface. 3. The recording sheet according to claim 2, wherein the film in which the printing ink is solidified forms a regular pattern. 4. The printing ink contains a lubricant.
Any one recording sheet.