JP2000335086A - Ink jet recording sheet having erasable print pattern and method for forming pattern using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate erasing of only an unnecessary portion of a print pattern and, to form a clear print pattern again on an erased portion by laminating an ink receptive layer carrying an ink jet print pattern with a pigment ink having no compatibility with the receptive layer on a surface of a base material film. SOLUTION: The ink jet recording sheet having the erasable print pattern is formed by laminating an ink receptive layer carrying an ink jet print pattern of a pigment ink having no compatibility with the receptive layer on at least one surface of a base material film. A pattern is formed by ink jet by using the ink on the receptive layer of the sheet, and a position desired to be erased of the formed pattern is erased by using an eraser. Then, a pattern is again formed at the erased position by using an ink jet, a pen, a pencil or an electrophotogrpahic copying means. A thickness of the film is suitably 50 to 100 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording sheet which can be erased by an eraser formed by ink jet printing, and on which a new pattern can be added or printed, if necessary. It is.

[0002]

2. Description of the Related Art In recent years, with the spread of computer utilization technology, printing out data created by a computer using a printer has become popular. Printers used at that time include dot impact printers, laser printers, thermal printers, and ink jet printers.These are that there is almost no mechanical noise during printout, and the running cost associated with printout is low. Printers are widely used.

[0003] Normally, plain paper or coated paper is used as the paper for printing out by an ink jet printer. However, recently, paper made of a plastic film has been used because of its excellent water resistance and storage stability. Recording sheets provided with an ink receiving layer made of a hydrophilic polymer on the surface of a material are often used.

On the other hand, it is often necessary to erase a part of the print pattern of a recording sheet printed out by the ink jet printer and rewrite it, and some recording sheets have been proposed. (JP-A-8-207395).

[0005] However, when the recording sheet is printed out by an ink-jet printer using the recording sheet, if it is erased and then printed out again, even the pattern which does not need to be erased may be erased or printed later. In addition to the drawback that the out-printed pattern becomes unclear, the drawback is that after a long time, the pattern is fixed and cannot be erased.

[0006]

SUMMARY OF THE INVENTION The present invention overcomes the drawbacks of the conventional erasable recording sheet, and makes it possible to easily erase only unnecessary portions of a print pattern printed out by an ink jet printer. It is an object of the present invention to provide a novel ink jet recording sheet which can form a clear print pattern on a portion again and which does not show a decrease in erasing performance even after a long period of erasing of the portion to be erased. Things.

[0007]

Means for Solving the Problems The present inventors can selectively erase only an unnecessary portion of a print pattern printed out by an ink jet printer, and can form a print pattern again on the erased portion. As a result of intensive research to develop an ink jet recording sheet, the ink receiving layer provided on the base film,
The present inventors have found that if a printing pattern is formed using a pigment ink having no compatibility, a printed portion can be erased as necessary and a printing pattern can be formed thereon again, and based on this finding, the present invention Was reached.

That is, the present invention is characterized in that at least one surface of a substrate film has an ink receiving layer carrying an ink jet print pattern made of a pigment ink having no compatibility with the ink receiving layer. Ink jet recording sheet with a simple print pattern, and on the ink receiving layer of this ink jet recording sheet, a pattern is formed by ink jet using a pigment ink, and the portion of the formed pattern to be erased is erased using an eraser, In the erased place, inkjet, pen,
Another object of the present invention is to provide a pattern forming method characterized in that a pattern is formed again by a pencil or an electrophotographic copying means.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The substrate film of the recording sheet of the present invention is not particularly limited, and can be arbitrarily selected from those conventionally used as a substrate of a recording sheet for an ink jet printer. . Such materials include, for example, polyethylene terephthalate,
Any one can be selected from polyethylene, polypropylene, polyamide and the like, and among them, polyethylene terephthalate is particularly preferable.
The thickness of the substrate film is usually in the range of 25 to 250 μm, preferably 50 to 100 μm. As this substrate film, a film which has been subjected to a mat treatment as required can be used.

In the recording sheet of the present invention, an ink receiving layer is provided on at least one side, that is, one side or both sides of the base film. In order to improve the adhesion between the ink receiving layer and the base film, If desired, an undercoat layer may be provided between the base film and the ink receiving layer. As the undercoat layer, a saturated polyester resin, a urethane resin, or the like is usually used, but a urethane resin is particularly preferable because of good adhesion to the ink receiving layer.
The thickness of the undercoat layer is usually in the range of 0.5 to 1.5 μm.

The ink receiving layer can be arbitrarily selected from those conventionally used as a receiving layer of an ink jet recording sheet. For example, (A) a crosslinked polyvinyl alcohol and (B) A layer mainly composed of polyvinylpyrrolidone and (C) synthetic silica is suitable. The polyvinyl alcohol used as the component (A) usually has a degree of polymerization of at least 1,000, preferably at least 100.
Those having a range of 0 to 3000 are preferred. This polymerization degree is 100
When it is less than 0, the ink drying property (ink absorption property) and the water resistance of the film become insufficient. Further, as the polyvinyl alcohol, partially saponified or completely saponified polyvinyl acetate having a saponification degree of 75 mol% or more, in particular, a saponification degree of 7 or more.
Partially saponified products of 5 to 90 mol% are preferred. If the degree of saponification is less than 75 mol%, the ink absorption rate is undesirably low.

The component (A) may be cross-linked with a cellulose-reactive cross-linking agent or urea. The cellulose-reactive cross-linking agent is a cross-linking agent having reactivity to hydroxyl groups of cellulose, such as dimethylol ethylene urea, dimethylol propylene urea, dimethylol alkyl triazone, Examples thereof include cyclic or heterocyclic urea derivatives such as methylated dimethyloluron and dimethylolglyoxal monourein. These react with the functional groups in the polyvinyl alcohol in the presence of a catalyst such as ammonium chloride, ammonium nitrate, ammonium sulfate or the like to form a three-dimensional structure.
The cellulose-reactive crosslinking agent or urea is used in an amount of usually 4 to 12 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of polyvinyl alcohol. When the amount is less than 4 parts by weight, the effect of improving water resistance is not sufficiently exhibited,
If the amount exceeds 12 parts by weight, the ink absorbency decreases. Also,
The catalyst used in combination with this is a
Usually, it is used at a ratio of 20 to 100% by weight.

Next, the polyvinyl pyrrolidone used as the component (B) generally has a molecular weight of 40,000 or more, preferably in the range of 600,000 to 28,000,000. When the molecular weight is less than 40,000, the ink absorption speed and receptivity are insufficient, and as a result, the drying property of the ink is reduced. The synthetic silica used as the component (C) has an oil absorption of 75 to 105 ml and a specific surface area of 500 to 900 m ² / g.
Are preferred. If the oil absorption is less than 75 ml or the specific surface area is less than 500 m ² / g, when the erased portion is again ink-jet printed with the dye ink, the dye ink cannot sufficiently penetrate and be absorbed, and the oil absorption is more than 105 ml. Or a specific surface area of 90
If it is larger than 0 m ² / g, the pigment ink tends to have compatibility, so that an unnecessary portion of the pattern printed with the pigment ink cannot be erased by an eraser or the like.

The synthetic silica has an average particle size of 0.1.
Those having a range of 5 to 15 μm, preferably 0.8 to 9 μm are suitable. When the average particle diameter is less than 0.5 μm, the ink drying property is poor. When the average particle diameter is more than 15 μm, the dot shape does not easily become a perfect circle, and the image resolution tends to decrease.

Particularly preferred as the synthetic silica of the component (C) is a mixture of synthetic silica having an average particle size of 3.5 μm or less and synthetic silica having an average particle size of 6.0 μm or more. This combination can provide a necessary pattern protection effect. Also, this synthetic silica has
Various matting agents can be added according to the purpose.

The content ratio of the component (A) to the component (B) is preferably in the range of 8: 2 to 6: 4 by weight. When the proportion of the component (A) is less than this, the water resistance is reduced and stickiness is caused. When the proportion of the component (A) is greater than this, printing is performed again using the dye ink on the erased portion. The print pattern becomes unclear due to low absorption.

Next, the content of the component (C) is 30 to 30 parts by weight based on the total weight of the components (A) and (B) of 100 parts by weight.
100 parts by weight, preferably from 40 to 80 parts by weight. If the amount is less than 30 parts by weight, the ink drying property will be poor, and if it exceeds 100 parts by weight, the water resistance will decrease.

The recording sheet of the present invention can be prepared as follows. That is, first, the component (A),
The component (B) and the component (C) are dissolved or dispersed in an aqueous medium at a predetermined ratio, respectively, to prepare a coating solution having a solid concentration of about 10 to 15% by weight. The ink receiving layer is provided on the undercoat layer by coating and drying according to a conventional method. At this time, conventionally used various additives such as a surfactant, a lubricant, a stabilizer, and a coloring agent can be added to the coating liquid. The thickness of the ink receiving layer is usually 5 to
It is in the range of 30 μm, preferably 10 to 20 μm.

In the present invention, a dot shape adjusting agent-containing layer can be provided, if desired, on the ink receiving layer thus provided. As the dot shape adjusting agent, for example, a quaternary ammonium salt type acrylic resin is preferable. Specific examples of the quaternary ammonium salt type acrylic resin include a copolymer salt of an alkyl acrylate or an alkyl methacrylate with a dialkylamino acrylate or a dialkylaminoalkyl methacrylate. Such quaternary ammonium salt type acrylic resins are known, for example, a molar ratio of butyl methacrylate to dimethylaminoethyl methacrylate of 1:
The quaternary salt of the copolymer (1) is commercially available.

To form this dot shape adjusting agent-containing layer, the dot shape adjusting agent was dissolved in a suitable solvent, for example, alcohol or a mixture of alcohol and water, and this solution was applied on the ink receiving layer. Then, it may be dried. At this time, the dot shape adjusting agent may be formed on the ink receiving layer, or may be partially dissolved or impregnated in the ink receiving layer.

The coating amount of the dot shape adjusting agent is 3 to 10
The range of g / m ² is appropriate. When the coating amount of the dot shape adjusting agent is less than 3 g / m ² , the sharpness (image resolution) of the image becomes insufficient, and when it exceeds 10 g / m ² , the ink absorbency and the ink drying property decrease. This layer has the effect of forming the dot shape to a more perfect circle and further preventing the ink from bleeding.

In the present invention, when the ink receiving layer and the dot shape adjusting agent-containing layer are provided on one side of the base film, the mat layer may be formed on the back surface of the base film, that is, on the side opposite to the ink receiving layer. Alternatively, an ink receiving layer can be provided. The mat layer is formed by a binder and a matting agent.Examples of the binder include a thermoplastic resin, a thermosetting resin, a photocurable resin, and the like.Specifically, acrylic, urethane, polyester, Examples of each resin include vinyl chloride resins. As the matting agent, for example, silica, zirconia, clay, kaolin, alumina, titania, zeolite, calcium carbonate, barium sulfate, magnesium hydroxide, calcium phosphate, inorganic powders such as glass, acrylic resin, urethane resin, Vinyl chloride resin, benzoguanamine resin,
Synthetic resin powders such as benzoguanamine / melamine / formaldehyde condensate are exemplified. The average particle size of the matting agent is 0.1 to 20 μm, preferably 2 to 10 μm.
Is preferable. Further, when the ink receiving layer is also formed on the back surface of the base film, the same one as provided on the front surface of the base film may be provided, or the other, for example, does not contain a matting agent, Alternatively, a transparent ink receiving layer containing a very small amount may be provided.

The thickness of the mat layer is advantageously in the range of 1 to 10 μm, preferably 3 to 7 μm, from the viewpoint that curl prevention and good writability are obtained. Further, the mat layer may contain those conventionally used as additives, for example, a surfactant, a lubricant, a stabilizer, and a colorant.

The recording sheet of the present invention has a printing pattern formed by ink-jet printing with a pigment ink on a printing sheet having the above-described structure. Since it has no compatibility with the layer, it can be easily erased with an eraser or the like. The pigment ink used at this time can be arbitrarily selected from those having no compatibility with the ink receiving layer. Examples of such pigments include pigments such as synthetic inorganic pigments, azo pigments, lake pigments and phthalocyanine pigments dispersed in vehicles such as water, aqueous solutions containing surfactants and dispersants, and solvents. .
This pigment has a particle size of 0.5 to 2 μm, preferably about 1 μm.

In the recording sheet of the present invention, when a print pattern is formed again after a print pattern that has been erased, dye ink may be used for a pattern that does not need to be erased, and it is necessary to further erase the pattern. For some patterns, pigment ink may be used.
The dye ink is not particularly limited, and may be arbitrarily selected from those used in ordinary inkjet printing. Such include, for example, malachite green, rhodamine B or G,
Dyes such as Victoria Blue B, Permanent Green, Permanent Rhodamine and Permanent Blue are dissolved in vehicles such as mineral oil, vegetable oil, tung oil, synthetic drying oil and alkyd resin oil. Further, as the pigment ink, the same ink as that used for forming the print pattern carried in advance can be used.

In the ink jet recording sheet of the present invention, the surface of the ink receiving layer may be matted so that the erased portion can be further easily written with a writing instrument such as a pencil or a pen. In the ink jet recording sheet of the present invention, since the pigment ink forming the ink jet print pattern does not have compatibility with the ink receiving layer, it does not penetrate into the ink receiving layer and is merely supported. It is easily erased by rubbing with an eraser or the like. The pattern formed by the pigment ink can be erased for a long time, and can be easily erased even after being left for 30 days, for example.

[0027]

Next, the present invention will be described in more detail with reference to examples.

Example 1 6 parts by weight of polyvinylpyrrolidone (molecular weight: 1280000), 14 parts by weight of polyvinyl alcohol (polymerization degree: 2,000, saponification degree: 88.0 mol%), synthetic silica powder having an average particle diameter of 3.5 μm (specific surface area: 700 m ²⁾ / G) 6 parts by weight, 1.4 parts by weight of dimethylol glyoxal monourein, which is a cellulose-reactive crosslinking agent, 0.3 parts by weight of ammonium chloride, 40 parts by weight of ethanol, 20 parts by weight of propylene glycol monomethyl ether and 108 parts of water Then, 0.3 parts by weight were mixed to prepare a coating liquid for forming an ink receiving layer.

On one side of a polyethylene terephthalate film having a thickness of 50 μm, a urethane resin having a thickness of 1.0
After the undercoat layer having a thickness of μm was provided, the coating solution was applied onto the undercoat layer using a wire bar, and heated at 130 ° C. for 5 minutes to form an ink receiving layer having a thickness of about 15 μm.

Next, Hewlett-Packard (Hew
Lett Packard, Inc., an inkjet plotter (Design Jet 750C), and a pigment ink (Hewlett Packard, trade name "5
1645A)), the basic structural part of the building design was inkjet printed.

After leaving for 1 hour, when a part of the print pattern was rubbed with an eraser, the changed part of the basic structure could be erased. After leaving for 2 months, the same operation was performed, but there was almost no change in the erasing performance of the inkjet print pattern using the pigment ink. For comparison, a commercially available inkjet recording paper was subjected to an erasure test on the same pattern that was inkjet-printed with the pigment ink described above. As a result, the erasure was possible after one hour, but was completely eliminated after two months. Not erased.

Example 2 6 parts by weight of polyvinylpyrrolidone (molecular weight: 1280000), 14 parts by weight of polyvinyl alcohol (degree of polymerization: 2,000, saponification degree: 88.0 mol%), synthetic silica powder having an average particle size of 3.5 μm (specific surface area: 700 m ²⁾ / G) 6 parts by weight, 4 parts by weight of calcium carbonate powder having an average particle size of 2.0 μm, 1.4 parts by weight of dimethylol glyoxal monourein which is a cellulose-reactive crosslinking agent, 0.3 parts by weight of ammonium chloride, ethanol 40 parts by weight, 20 parts by weight of propylene glycol monomethyl ether and 108.3 parts by weight of water were mixed to prepare a coating liquid for forming an ink receiving layer.

On one side of a polyethylene terephthalate film having a thickness of 50 μm, a urethane resin having a thickness of 1.0
After the undercoat layer having a thickness of μm was provided, the coating solution was applied onto the undercoat layer using a wire bar, and heated at 130 ° C. for 5 minutes to form an ink receiving layer having a thickness of about 15 μm.

Further, a quaternary ammonium salt type acrylic resin [Saftomer CP-2000, manufactured by Mitsubishi Yuka Co., Ltd.]
1.0 part by weight, 10.0 parts by weight of ethanol and 89.0 parts of water
A part of the dot shape adjusting agent-containing layer forming liquid is prepared, applied to the ink receiving layer, and dried to form a dot shape adjusting agent-containing layer containing 4 g / m ² of the dot shape adjusting agent. Formed.

Next, on the back surface of the ink receiving layer, 20 parts by weight of a binder (acrylic copolymer resin), 10 parts by weight of a matting agent (synthetic silica powder, average particle size of 3.5 μm) and water 7
0 parts by weight of a mat layer forming coating solution,
By heating at 2 ° C. for 2 minutes, a mat layer having a thickness of 5 μm was formed.

With respect to the recording sheet thus obtained, a printing pattern was formed using a pigment ink in the same manner as in Example 1, and an erasing test was performed with an eraser. The same results as in Example 1 were obtained. Was.

Examples 3 and 4 A recording film was produced in exactly the same manner as in Example 2 except that the composition shown in Table 1 was used as the coating liquid for forming the ink receiving layer. A print pattern was formed using a pigment ink in the same manner as in Example 2, and an erasure test was performed using an eraser. As a result, exactly the same results were obtained.

Comparative Examples 1 and 2 A recording film was produced in the same manner as in Example 2 except that the composition shown in Table 1 was used as the coating liquid for forming the ink receiving layer. A print pattern was formed using a pigment ink in the same manner as in Example 2, and an erase test was performed using an eraser. As a result, the print pattern could not be erased.

[0039]

[Table 1] (Note) 1) Synthetic silica powder: particle size 3.5 μm, oil absorption 95 m
1, specific surface area 700 m ² / g 2) synthetic silica powder: particle diameter 6.0 μm, oil absorption 95 m
1, specific surface area 700 m ² / g 3) synthetic silica powder: particle size 3.5 μm, oil absorption 210 m
1, specific surface area 300m ² / g

[0040]

According to the recording sheet of the present invention, a pattern including a portion to be erased as necessary can be subjected to ink-jet printing with a pigment ink, and the pattern can be corrected as needed by an eraser or the like. Moreover, there is an advantage that the correction portion is clear. In addition, there is an advantage that the erasing performance of the print pattern portion by the pigment ink does not decrease over a long period.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Sakaguchi 4-11-2 Ginza, Chuo-ku, Tokyo F-term (reference) 2mar 086 BA02 BA15 BA55 4L055 AG18 AG57 AG64 AG71 AH02 AH37 AJ04 BE09 FA30 GA09

Claims (4)

[Claims] 1. An erasable print pattern comprising an ink receiving layer carrying an ink jet print pattern made of a pigment ink having no compatibility with an ink receiving layer on at least one surface of a substrate film. Inkjet recording sheet. 2. The pattern erasable inkjet recording sheet according to claim 1, wherein the surface of the ink receiving layer is matted. 3. The pattern erasable inkjet recording material according to claim 1, wherein the ink receiving layer absorbs a solvent in the pigment ink but does not absorb the pigment. 4. A pattern is formed by ink jet using a pigment ink on an ink receiving layer of the pattern erasable ink jet recording sheet according to claim 1, and a portion of the formed pattern to be erased is obtained. A pattern forming method comprising: erasing with an eraser; and forming a pattern again on the erased portion by means of an ink jet, a pen, a pencil, or electrophotographic copying means.