JPH11268483A - Writing and erasing methods, and ink and eraser to be used for same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a complete erasing, and also eliminate a peripheral contamination due to dust or the like by a method wherein a writing is performed by using an ink wherein one kind or more of dyes selected from methine dyes and azo methine dyes, are dissolved with water, and the written images are erased by an eraser containing at least one kind of reducing agent and water. SOLUTION: When a writing is performed on a writing board having an ink receiving layer such as a white board, an ink wherein one kind or more of dyes selected from methine dyes and azo methine dyes are dissolved with water, is used. In the meantime, an eraser which is used as a set with the ink, contains a reducing agent and water, and by wiping off the written images by the eraser, the dyes which form the images in the ink receiving layer react with the reducing agent, and disappear, and at the same time, the dyes move into the eraser. By this method, in either case of before or after a usage, the functional part of the eraser does not induce a coloring by sticking to hand, and when the ink is adhered, the ink can be easily washed away with water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a writing and erasing method for a writing board having an ink receiving layer such as a white board, and an ink and an eraser using the same.

[0002]

2. Description of the Related Art Conventionally, a blackboard has been used as a simple means for providing information to many people such as a bulletin board. The blackboard can easily draw (or write) characters and figures using chalk, and can be easily erased by wiping it off with an eraser such as cloth. However,
When drawing characters or figures using chalk or wiping drawn figures or the like, there is a problem that dust of chalk floats around the blackboard and adversely affects the respiratory organs of the human body.

For this reason, as an alternative to this blackboard,
White boards (white boards) that do not generate chalk dust are commonly used. In general, a white board is formed by forming a white resin layer (ink receiving layer) such as a white paint on a base material of a metal plate such as aluminum.

[0004] The surface of a white board simultaneously satisfies both the characteristics of writing, in which characters and images can be easily recorded with a hydrophilic ink pen, and erasability, in which erasing can be easily performed with an erasing device such as cloth. You need to be able to do it.

Heretofore, a writing instrument for a white board has used ink obtained by suspending and stirring a powder pigment in alcohol. For this reason, after erasing, when erasing with an erasing tool (eraser), especially if left unerased for a long time, it becomes difficult to wipe with a dry cloth, and the wiping of the powder pigment is incomplete or There were problems that the powder pigment was scattered and stained the area around the white board, and the stains on the hands were difficult to remove by washing with water. In addition, due to the characteristics of the ink, the pigment absorption efficiency is poor,
There is also a problem that it is difficult to follow early writing, causing blurring and unevenness. In addition, since the insoluble powder pigment is fine and easily scattered, it is easily absorbed by the lungs of teachers or the like when writing or erasing, and health problems cannot be ignored.

To cope with such a problem, Japanese Patent Laid-Open No.
-59547, JP-A-7-90214, JP-A-53
JP-A-82507 discloses an ink in which an oil-soluble coloring agent which forms a color with an aid of a coloring agent is dispersed in alcohol, and it is said that such an ink can be decolorized with water. However, even when such an ink is used, since the color former is oil-soluble, decoloring with water is insufficient, or blurring occurs when writing quickly,
Unevenness cannot be completely prevented. Nor has it been possible to completely prevent health problems.

[0007] Therefore, an ink and an eraser which solve these problems are desired.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a so-called white board or the like which is free from blurring and unevenness even when writing is performed quickly, and that the written image is completely erased. It is an object of the present invention to provide a writing and erasing method which can perform erasure without any problem and has no problem of surroundings due to dust or the like, and an ink and an eraser used for the method.

[0009]

The above object is achieved by the present invention described below. (1) On a writing board having an ink receiving layer, writing is performed using an ink in which one or more dyes selected from methine dyes and azomethine dyes are dissolved in water, and the written image is written with at least one reducing agent and water. And erasing by an eraser containing the following. (2) The writing and erasing method according to (1), wherein the glossiness of the surface of the ink receiving layer is in the range of 1 to 60, and the contact angle of the surface with water is in the range of 50 to 80 degrees. (3) 1 selected from methine dyes and azomethine dyes
Ink used in the writing and erasing method according to the above (1) or (2), wherein at least one kind of dye is dissolved in water. (4) The ink according to the above (3), which contains a water-soluble polymer and / or a surfactant. (5) The ink according to (4) or (5), wherein the dye is selected from compounds represented by formulas (I) to (VI).

[0010]

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Wherein A ¹ and A ² each represent an acidic nucleus, A ³ represents a phenol nucleus, a naphthol nucleus or an acidic nucleus, B ¹ represents a basic nucleus, and B ² represents an onium of a basic nucleus. And Q represents an aryl group or a heterocyclic group.
L ¹ , L ² and L ³ each represent a methine group;
J and p are each an integer of 0 to 3,
q is an integer of 0 to 4, and r is 1 or 2. (6) An eraser containing at least one reducing agent and water, which is used in the writing and erasing method according to the above (1) or (2).

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the present invention, when writing on a writing board having an ink receiving layer such as a white board, an ink in which one or more dyes selected from methine dyes and azomethine dyes are dissolved in water is used. In such an ink, the dye is a water-soluble dye, and the solvent is mainly composed of water.
It has good dye absorption efficiency and does not cause blurring or unevenness even when writing quickly. In addition, there is no dependency on the type or form of the writing pen felt tip, and therefore, it can be used as any conventional felt pen form.

On the other hand, the eraser used in combination with the above-mentioned ink of the present invention contains a reducing agent and water, and may be, for example, cloth or paper impregnated with an aqueous solution of the reducing agent. By wiping the image, the dye forming the image in the ink receiving layer reacts with the reducing agent to erase the color and move to the eraser. That is, it is considered that the methine chain or the azomethine chain of the methine dye or the azomethine dye is attacked by the reducing agent to decolor. Therefore, erasing is complete, there is no generation of dye dust or the like at the time of erasing, and there is no dirt or health problem. In addition, before and after use, the functional part of the eraser does not adhere to the hand and cause coloring,
When the ink adheres, the ink can be easily washed away by washing with water.

The ink of the present invention contains a water-soluble dye selected from methine dyes and azomethine dyes. The solubility of these water-soluble dyes in water (25 ° C.) is 1 g /
Liter or more, more preferably 3
１００100 g / liter.

The preferred dyes used in the present invention are represented by the following general formulas (I), (II), (III), (IV),
Compounds represented by (V) and (VI).

[0016]

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[0017] In the formula, A ^1, A ² each represents an acidic nucleus, A ³
Represents a substituted or unsubstituted phenol, naphthol or acidic nucleus, B ¹ represents a basic nucleus, B ² represents an onium form of the basic nucleus, Q represents an aryl group or a heterocyclic group,
¹ , L ² and L ³ each represent a methine group, and i is 0, 1,
2, j and p represent 0, 1, 2, and 3, respectively, q represents 0, 1, 2, 3, and 4, and r represents 1, 2. The compounds of the general formulas (I) to (VI) have at least one compound per molecule.
It is preferable to have one water-soluble group (for example, a sulfo group, a carboxyl group, a phosphate group and a salt thereof).

The acidic nucleus represented by A ¹ , A ² or A ³ is
Preference is given to groups of cyclic ketomethylene compounds or groups of compounds having a methylene group sandwiched between electron-withdrawing groups. Examples of the group of the cyclic ketomethylene compound include 2-
Pyrazolin-5-one, rhodanin, hydantoin, thiohydantoin, 2,4-oxazolidinedione, isoxazolidinedione, isoxazolone, barbituric acid, thiobarbituric acid, indandione, dioxopyrazolopyridine, hydroxypyridine, pyrazo Lysinedione, 2,5-dihydrofuran-2-one, pyrrolin-
2-one, 3-dicyanomethylene-2,3-dihydrothianaphthene-1,1-dioxide, 3-oxo-2,3
-Dihydrothianaphthene-1,1-dioxide. These may have a substituent.

The group of the compound having a methylene group sandwiched between electron-withdrawing groups can be represented by Z ¹ CH ₂ Z ² ;
Here, Z ¹ and Z ² are —CN, —SO ₂ R ¹ , and —CO, respectively.
^{R 1, -COOR 2, -CONHR 2} , -SO 2 NHR 2,
-C [= C (CN) ₂ ] R ¹ , or -C [= C (CN)
₂ ] NHR ¹ R ¹ represents an alkyl group, an aryl group, or a heterocyclic group, R ² represents a hydrogen atom, a group represented by R ¹ , and each of these may have a substituent.

Examples of the basic nucleus represented by B ¹ include pyridine, quinoline, indolenine, oxazole, imidazole, thiazole, benzoindolenine, benzoxazole, benzimidazole, benzothiazole,
Oxazoline, naphthoxazole, naphthothiazole and pyrrole can be mentioned. Each of these may have a substituent. B ² is an onium of a basic nucleus, and examples thereof include the onium of a basic nucleus described in B ¹ above. The onium compound preferably forms an inner salt.

Examples of the aryl group represented by Q include a phenyl group and a naphthyl group, each of which may have a substituent. Particularly, a phenyl group substituted by a dialkylamino group, a hydroxyl group, or an alkoxy group is most preferable. Examples of the heterocyclic ring in the heterocyclic group represented by Q include pyrrole, indole, furan, thiophene, imidazole, pyrazole, indolizine, quinoline, carbazole, phenothiazine, phenoxazine, indoline, thiazole, pyridine, pyridazine, thiadiazine , Pyran, thiopyran, oxadiazole, benzoquinoline,
Thiadiazole, pyrrolothiazole, pyrrolopyridazine, tetrazole, oxazole, coumarin, and coumarone can be mentioned. Each of these may have a substituent.

The methine groups represented by L ¹ , L ² and L ³ may have a substituent, and the substituents are connected to each other to form a 5- or 6-membered ring (for example, cyclopentene, cyclohexene, cycloheptene). ) May be formed.

There are no particular restrictions on the substituents that each of the above groups may have. For example, a carboxyl group (including a salt), a sulfo group (including a salt), a sulfonamide group having 1 to 10 carbon atoms (for example, methanesulfonamide, benzenesulfonamide, butanesulfonamide, n-octanesulfonamide), a carbon number of 0 10 to 10 sulfamoyl groups (eg, unsubstituted sulfamoyl, methylsulfamoyl, phenylsulfamoyl, butylsulfamoyl), carbon number 2
To 10 sulfonylcarbamoyl groups (for example, methanesulfonylcarbamoyl, propanesulfonylcarbamoyl, benzenesulfonylcarbamoyl), having 1 to 1 carbon atoms
0 acylsulfamoyl groups (eg, acetylsulfamoyl, propionylsulfamoyl, pivaloylsulfamoyl, benzoylsulfamoyl), having 1 to 1 carbon atoms
8 linear or cyclic alkyl groups (eg, methyl, ethyl, propyl, isopropyl, butyl, t-butyl, hexyl, cyclopropyl, cyclohexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl, benzyl, phenethyl , 4-carboxybenzyl,
2-diethylaminoethyl), an alkenyl group having 2 to 8 carbon atoms (eg, vinyl, allyl), an alkoxy group having 1 to 8 carbon atoms (eg, methoxy, ethoxy, butoxy), a halogen atom (eg, F, Cl, Br), An amino group of numbers 0 to 10 (eg, unsubstituted amino, dimethylamino, diethylamino, carboxyethylamino),
10 ester groups (e.g., methoxycarbonyl, ethoxycarbonyl), C1-10 amide groups (e.g., acetamido, propionylamino, benzamide), C1-10 carbamoyl groups (e.g., unsubstituted carbamoyl, methylcarbamoyl, Ethyl carbamoyl,
Phenylcarbamoyl), an aryl group having 6 to 10 carbon atoms (eg, phenyl, naphthyl, 4-carboxyphenyl, 3-carboxyphenyl, 3,5-dicarboxyphenyl, 4-methanesulfonamidophenyl, 4-butanesulfonamidophenyl) An aryloxy group having 6 to 10 carbon atoms (for example, phenoxy, 4-carboxyphenoxy, 3-methylphenoxy, naphthoxy);
8 alkylthio groups (eg, methylthio, ethylthio,
Octylthio), an arylthio group having 6 to 10 carbon atoms (eg, phenylthio, naphthylthio), an acyl group having 1 to 10 carbon atoms (eg, acetyl, benzoyl, propanoyl, morpholinocarbonyl), a sulfonyl group having 1 to 10 carbon atoms (eg, methanesulfonyl) Benzenesulfonyl), a ureido group having 1 to 10 carbon atoms (for example, ureido,
Methylureido), a urethane group having 2 to 10 carbon atoms (eg, methoxycarbonylamino, ethoxycarbonylamino), a cyano group, a hydroxyl group, a nitro group, and a heterocyclic group (eg, a 5-carboxybenzoxazole ring, a pyridine ring as a heterocyclic ring) , A sulfolane ring, a furan ring, a pyrrole ring, a pyrrolidine ring, a pyrrolidinone ring, a pyrrolidine-dione ring, a morpholine ring, a piperazine ring, and a pyrimidine ring). A ¹ , A ² , A ³ , B ¹ , B ² , and Q may be linked together to form a ring.

Among the compounds represented by the general formulas (I) to (VI), particularly preferred compounds are (I), (II) and (II)
Among them, the acidic nuclei of A ¹ and A ^{2 and} the acidic nucleus when A ³ is an acidic nucleus are 2-pyrazolin-5-one, 2,4-oxazolidinedione, Particularly preferred are isoxazolone, barbituric acid, indandione, dioxopyrazolopyridine, hydroxypyridine, pyrazolidinedione and 2,5-dihydrofuran-2-one.

The general formulas (I) to (I) used in the present invention are described below.
Specific examples of the compound represented by (VI) will be given, but the present invention is not limited thereto.

[0026]

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[0027]

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[0028]

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[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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The dye used in the present invention is described in International Patent WO8.
8/04794, European Patent EP274723A
No. 1, No. 276566, No. 299435, No. 696
758A1, JP-A-52-92716, and 55-1
55350, 55-155351, 61-20
Nos. 5934 and 48-68623, U.S. Pat.
Nos. 7583, 3486897 and 3746539
Nos. 3,933,798, 4,130,429, and 40
No. 40841, JP-A-2-282244 and 3-79
No. 31, 3-167546, and the like, or can be synthesized according to the method.

These dyes may be used alone or in combination of two or more, and the amount used is preferably from 1 to 100 g, more preferably from 2 to 70 g, per liter of ink. .

The solvent in the ink of the present invention may be water alone.
A lower alcohol such as methyl alcohol, ethyl alcohol, or isopropyl alcohol may be contained in the range of 1 to 75% by weight.

The ink of the present invention contains a water-soluble polymer and / or
Or it is preferable to contain a surfactant. The addition of the water-soluble polymer is effective in preventing drying of the ink in the writing instrument and adjusting the viscosity of the ink. Further, the addition of a surfactant is effective in improving the wettability to a recording material such as a white board, that is, the writing property. Some water-soluble polymers and surfactants have these functions.

Examples of the water-soluble polymer include polyvinyl alcohol, alginate, cellulose, cellulose derivatives, carboxyvinyl polymer, polyethylene oxide, sodium polyacrylate, tragacanth, gum arabic, guar gum, gelatin, glue, pectin,
Locust bean gum, galactose mannan, agar, starch and the like.

Among them, in order to improve the stability over time of the ink, it is preferable to dissolve it in water, and its solubility in water (25 ° C.) is 1 g / liter or more, especially 3 to 1
Those having a weight of 50 g / liter are preferred. In particular,
Polyvinyl alcohol, hydroxyethyl cellulose,
Carboxymethyl cellulose and the like are preferably used.
One type of water-soluble polymer may be used alone or two or more types may be used in combination, and the amount of the water-soluble polymer used is preferably 5 to 50% by weight based on the dye.

As the surfactant, any known surfactants can be used. For example, US Pat. No. 4,060,025, JP-A-62-215272, JP-A-1-201655,
No. 4-125548, U.S. Pat.
European Patent EP678787A2, JP-A-63-119
No. 35, No. 63-60446, anionic surfactants, nonionic surfactants and single or plural combinations thereof, amphoteric surfactants as described in US Pat. No. 3,542,581 and European Patent EP 569,074 A1 Surfactants and fluorinated surfactants as described in EP 602 428 A1 can also be used. It is particularly preferable to use an anionic and / or nonionic surfactant, and more preferably, an anionic polymer as described in JP-A-4-324858, and JP-A-60-15.
An oligomer-type polymer described in No. 8437 or JP-A-7-13300 and a nonionic polymer described in U.S. Pat. No. 3,860,425 can be used.

Among them, those which are soluble in water are preferable for improving the stability over time of the ink, and the solubility in water (25 ° C.) is 5 g / l or more, especially 20 to 20 g / l.
Those having a weight of 200 g / liter are preferred. Specifically, saponin, sorbitan fatty acid esters such as sorbitan monolaurate, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol, monoglyceride, sodium dodecylbenzenesulfonate,
Sodium dodecyl sulfate and the like are preferably used.

One surfactant may be used alone or two or more surfactants may be used in combination, and the amount of the surfactant is preferably 1 to 50% by weight based on the dye.

In addition, a wetting agent such as polyethylene glycol and a preservative such as sodium citrate and sodium tartrate may be added to the ink of the present invention.

FIG. 1 shows a configuration example of a writing instrument containing the ink of the present invention. The writing implement 1 shown in FIG. 1 has an ink portion 11 in which the ink of the present invention is impregnated with a porous material or a long fiber material (for example, absorbent cotton, cotton, or the like) and is stored in a container. And a writing part 12 formed of a high quality material (for example, sintered polyethylene, sponge, felt core or hair of a brush tip), and the ink part 11 and a part of the writing part 12 are stored in a writing implement support part 13. Have been. A detachable cap 14 is attached to the tip of the writing unit 12 so as to cover the tip of the writing unit 12. Furthermore, the writing section 1 of the writing instrument support section 13
A refill cap portion 15 is provided on the side opposite to 2 and covers the ink portion 11 and, for example, when the ink of the ink portion 11 has been used, etc.
Is removed so that the ink unit 11 can be integrally replaced with a refill ink unit. The refill ink unit has the same configuration as the ink unit 11 in FIG. 1 and is a separate member.

The writing instrument according to the present invention is not limited to the illustrated example, but may be of various types.

On the other hand, the eraser of the present invention contains a reducing agent and water. Examples of the reducing agent include sodium sulfite, potassium sulfite, lithium sulfite, calcium sulfite, zinc sulfite, tin chloride (SnCl ₂ ), metal powder (eg, zinc powder, aluminum powder, etc.), hydrosulfite, and the like. Potassium sulfite, lithium sulfite, calcium sulfite, and zinc sulfite are preferred, and among them, sodium sulfite, potassium sulfite, and lithium sulfite are preferred, and sodium sulfite (Na ₂ SO ₃ ) is particularly preferred from the viewpoint of performance and safety.

Such an eraser uses a reducing agent of 0.2%.
Any aqueous solution containing 10 to 10% by weight may be used. In addition, as a solvent of such an aqueous solution, in addition to water, an alcohol such as methyl alcohol, ethyl alcohol, or isopropyl alcohol may be contained in an amount of 0.1 to 10% by weight. In addition, such an aqueous solution may contain a surfactant, a wetting agent (eg, diethylene glycol, triethylene glycol, and the like), a preservative, and the like.

The recording material on which writing is performed using the ink of the present invention is not particularly limited as long as it is a writing board having an ink receiving layer, and may be a so-called white board. In particular, in the present invention, it is preferable to use an ink receiving layer having a surface glossiness in the range of 1 to 60 and a contact angle of water on the surface thereof in the range of 50 to 80 degrees. Since the surface of the ink receiving layer having such properties has an appropriate affinity with the ink of the present invention,
Characters and the like can be recorded without blurring or repelling with such an ink writing implement, and the recorded characters and figures can be easily erased by the eraser of the present invention. The ink receiving layer has a relatively low glossiness and is excellent in antiglare properties.

Here, the gloss in the range of 1 to 60 means that the 60-degree specular gloss and the 45-degree specular gloss obtained by the method described in JIS-K-7105-1981 are:
Each means that it is in the range of 1 to 60.

The contact angle of the above surface with water is 25 ° C.
Is the value at.

The board having the ink receiving layer as described above may be formed by attaching a sheet having the above-described ink receiving layer on one surface of paper to an existing board or wall surface. By using such a sheet, the writing and erasing method using the ink and the eraser of the present invention can be performed using existing equipment. Further, such a sheet can be used as a projection screen sheet, and is preferable because it can be easily replaced and easily disposed.

As the paper constituting such a sheet,
Examples include base paper, base paper having a surface sizing agent applied to both sides, coated paper, and art paper. The base paper is
Natural pulp obtained from conifers, hardwoods, etc. as the main raw material,
If necessary, fillers such as clay, talc, calcium carbonate, and urea resin fine particles; sizing agents such as rosin, alkyl ketene dimer, higher fatty acid, epoxidized fatty acid amide, paraffin wax, alkenyl succinic acid; starch, polyamide polyamine epichlorohydrin; A paper strength enhancer such as polyacrylamide; a fixing agent such as a sulfate band or a cationic polymer; and the like are generally used. Further, a softening agent such as a surfactant and an epoxidized fatty acid amide (other than those for the sizing agent) may be added. Alternatively, paper obtained using synthetic pulp instead of natural pulp can be used, and paper obtained from a mixture of natural pulp and mixed pulp can also be used.

The paper used in the present invention is preferably coated paper or base paper having both surfaces coated with a surface sizing agent.

The surface sizing agent (or liquid) applied to the base paper surface is generally polyvinyl alcohol and / or
Alternatively, it is an aqueous solution of a modified product thereof. The aqueous solution may further include starch, carboxymethylcellulose, hydroxyethylcellulose, sodium alginate, high molecular compounds such as cellulose sulfate, gelatin and casein; metal salts such as calcium chloride, sodium chloride and sodium sulfate; and hygroscopic substances such as glycerin and polyethylene glycol. A coloring agent such as a dye; a whitening substance such as a fluorescent whitening agent; and a pH control agent such as caustic soda, aqueous ammonia, hydrochloric acid, sulfuric acid, and sodium carbonate. If necessary, a surfactant, a softening agent such as an epoxidized fatty acid amide, and a pigment may be added.

The method of impregnating the base paper with the surface sizing agent (liquid) can be performed by applying using a size press, a tab size, or a gate roll coaster.

The ink receiving layer provided on the paper is
This is a layer made of a polymer. Further, the pigment is preferably dispersed in the polymer. Further, the glossiness of the surface of the ink receiving layer is preferably in the range of 1 to 60, and the contact angle of the surface with water is preferably in the range of 50 to 80 degrees. Any polymer that satisfies such a contact angle can be used.

Examples of the polymer include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate (preferably aromatic polyesters), polystyrene such as syndiotactic polystyrene, polyvinyl chloride, and polyamide.

In the present invention, the polymer of the ink receiving layer is preferably polyester, particularly preferably amorphous polyester. The ink receiving layer is generally formed by melt-extruding the polyester on paper and laminating (so-called extrusion lamination). Lamination between the ink receiving layer and paper may be performed by a method such as hot melt lamination, dry lamination, or wet lamination.

As the above polyester, various polyesters synthesized from dicarboxylic acid and glycol, polyester obtained by ring-opening polymerization of caprolactone, and the like can be used without particular limitation.

Examples of dicarboxylic acids include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid,
Aromatic dicarboxylic acids such as 5-sodium sulfoisophthalic acid and their alkyl esters; aliphatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, adipic acid and sebacic acid and their alkyl esters, and trimellitic acid and pyromellitic Examples include polyfunctional carboxylic acids such as acids or alkyl esters thereof.

Examples of the glycol include a condensate of an alkylene glycol such as ethylene glycol, diethylene glycol and triethylene glycol, butanediol, neopentyl glycol, and a molecular weight of 150 to 2,000.
0 polyalkylene glycol, 1,4-cyclohexanedimetal and bisphenol A with n ethylene oxide added to both ends (n: 1 to 10).

The polyester obtained from the above materials is preferably an aromatic polyester. Further, the main structural unit is ethylene terephthalate or ethylene-2,6
A polyester comprising naphthalate (ie polyethylene terephthalate (PET) or polyethylene)
2,6-naphthalate (PEN)), and polyesters (copolymers) containing both units of ethylene terephthalate and ethylene-2,6-naphthalate. Particularly, PET is preferable.

The polyester ink-receiving layer is generally formed by melt-extruding the polyester on paper and laminating the same. The polyester thus melt-extruded generally becomes amorphous. Melt extrusion conditions for obtaining such an amorphous polyester are as follows: a polyester film melted from a die (eg, T-die) at a temperature higher than the melting point of the polyester by 20 ° C. or more is placed on a tilt roll maintained at 40 ° C. or less. This can be generally performed by discharging. Paper conveyed by the roll is laminated on the polyester film discharged onto the tilt roll, and an ink receiving layer is formed on the paper.

The melt extrusion of the polyester can be performed on both sides of the paper. At that time, the pressure-sensitive adhesive layer is provided on the polyester resin layer.

The melt extrusion of the polyester onto both sides of the paper can be carried out by repeating the above steps twice.

The surface of the paper from which the molten polyester is discharged is treated in advance with a paper (preferably coated paper, sizing paper) surface treatment (eg, increasing the CO group) in order to improve the adhesion between the paper and the polyester film. Is preferably performed.

Examples of the surface treatment include a fire treatment using a gas flame, an ultraviolet irradiation treatment, a corona discharge treatment, and an anchor coat treatment using an alkyl titanate or the like. Particularly, corona discharge treatment is simple and preferable. In the case of the corona treatment, the treatment is generally performed so that the contact angle with water becomes 70 degrees or less.

Examples of the material used for the anchor coat include organic titanium compounds, isocyanate compounds, polyethyleneimine resins, and polybutadiene resins. Examples of the organic titanium compound include alkyl titanates such as tetraisopropyl titanate, tetrabutyl titanate and tetrastearyl titanate; titanium acylates such as butoxytitanium stearate; and titanium chelates such as titanium acetylacetonate. Examples of isocyanate compounds include tolylene diisocyanate (TD
I), diphenylmethane diisocyanate (MDI),
Hexamethylene diisocyanate (HMDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI) and the like can be given.

The ink receiving layer preferably further contains a pigment (organic or inorganic fine particles). Examples of pigments include white pigments (eg, titanium dioxide, zinc white; barium sulfate, calcium carbonate, talc), black pigments (eg, carbon black, iron black), yellow pigments (eg, graphite, benzene yellow, ocher) ), Orange pigments (eg, red-mouthed yellow lead), red pigments (eg, red bean, thioindigo maroon), and blue pigments (eg, ultramarine, anthraquinone blue, and indaslen blue). Among these, white pigments (particularly titanium dioxide, barium sulfate, calcium carbonate or talc) are preferred. Pigments other than those described above can be preferably used as long as they can withstand the high temperature during melt extrusion of the polymer.

The average particle size of the above-mentioned pigments is generally preferably in the range from 0.01 to 5.0 μm, and is preferably in the range from 0.1 to 3.0 μm.
The range of μm is more preferred. The pigment is generally contained in the ink receiving layer in an amount of 1 to 100% by weight based on the polymer, and preferably in a range of 5 to 60% by weight.

In the ink receiving layer made of the polyester containing the pigment, the polyester and the pigment are melt-mixed in an extruder (eg, a single-screw or twin-screw kneading extruder) in the same manner as described above, and the melt-extrusion is performed on a chill roll. And formed by laminating with paper.

The ink receiving layer may be formed by applying a solution of a polymer such as the polyester or a dispersion of a polymer and a pigment on paper and drying.

The thickness of the ink receiving layer is 5 to 100 μm.
m (especially 10 to 80 μm). When the thickness is less than 5 μm or more than 100 μm, it is difficult to perform stable lamination with paper by high-speed extrusion.

Further, the surface roughness (Ra) of the ink receiving layer
Is preferably in the range of 0.3 to 3 μm at a cutoff value of 0.8 mm.

An adhesive layer can be provided on the front side (back side) of the paper on which the ink receiving layer is not provided, for the purpose of sticking to an existing board or the like. When an ink receiving layer (or a polymer layer) is also provided on the back surface for the purpose of preventing warpage and improving the strength, the ink receiving layer is provided thereon. The pressure-sensitive adhesive layer is generally formed by applying and drying a pressure-sensitive adhesive solution.

As a main component of the pressure-sensitive adhesive, a rubber-based polymer (eg, styrene / butadiene copolymer, polyisobutylene), an acrylic polymer, polyvinyl alcohol, polyvinyl ether, or the like is used. Usually, tackifiers (eg, rosin, rosin ester, ester gum, coumarone resin, coumarone / indene resin, terpene resin, hydrocarbon resin, oil-soluble phenol resin); softeners (eg, fatty acid ester, animal and vegetable fats and oils, wax, Heavy oil components);
And a pigment (eg, zinc white) are further added to the main component. If desired, fillers, anti-aging agents, stabilizers and the like may be further used.

The pressure-sensitive adhesive layer generally has a thickness of 1 to 50 μm.
m and preferably in the range of 3 to 30 μm.

It is preferable that a release sheet such as release paper is adhered to the surface of the pressure-sensitive adhesive layer. That is, a writing board sheet in which the ink receiving layer is provided on the front (front) surface of the paper and the pressure-sensitive adhesive layer and the release sheet are provided on the back surface is, for example, wound up in a roll shape. By cutting the roll from a necessary amount, peeling off the release sheet and pasting it on a blackboard, wall, or the like, the pasted portion can be used as a writing board.

The release sheet is generally formed by forming a layer of a release agent such as stearate, silicone, soap on the surface of paper or plastic film. The release sheet overlaps this release agent layer on the surface of the pressure-sensitive adhesive layer,
It is laminated and protects the pressure-sensitive adhesive layer from being exposed.

[0089]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. [Example 1] Polyethylene terephthalate (PET) 8
0 parts by weight and talc (average particle diameter in the major axis direction: 2.0 μm)
20 parts by weight and dispersed and mixed in a twin-screw kneading extruder.
After discharging from a die onto a chilled roll cooled at 300 ° C. to form a white film, the coated paper fed to a nip roll provided adjacent to the chilled roll was subjected to flame treatment (weight of 157 g). / m ² , thickness 160 μm; laminated on Esprit Coat FAM, manufactured by Nippon Paper Industries Co., Ltd., and an amorphous PET ink receiving layer (thickness: 30).
μm) was laminated on coated paper. The child roll is
Those having a surface roughness of Ra = 15 μm were used.

Next, a pressure-sensitive adhesive layer forming coating solution having the following composition was applied to the surface (back surface) of the paper on which the ink receiving layer was not provided by a knife roll coater and dried to obtain a 10 μm-thick film. An adhesive layer was formed to prepare a writing board sheet having an ink receiving layer and an adhesive layer formed on the surface of paper. Next, the pressure-sensitive adhesive layer of the writing board sheet was wound up in a roll shape so as to be in contact with the surface of the separately prepared release agent layer, thereby producing a writing board sheet with release paper.

(Coating solution for forming adhesive layer) Styrene / butadiene copolymer (as solid) 100 parts by weight Zinc white 5 parts by weight Oil-soluble phenol resin (as solids) 12 parts by weight Ester gum (as solids) 40 parts by weight Paraffin oil 25 parts by weight Coumarone indene resin (as solid) 40 parts by weight Normal hexane 500 parts by weight

The surface gloss of such a writing board sheet has a 60-degree specular gloss of 13 and a 40-degree specular gloss of 12, a contact angle to water of 74 degrees and a surface roughness Ra.
Was 0.9 μm. Gloss is JIS-K-7105
-HANDY GL gloss meter according to the method described in 1981
It was measured using OSS METER (HG-246, manufactured by Suga Test Instruments Co., Ltd.). The contact angle was measured at 25 ° C after leaving the board in a constant temperature room at 25 ° C for 1 hour (Kyowa Surface Science Co., Ltd.)
Was used for the measurement. The surface roughness Ra was measured at a cutoff value of 0.8 mm using Surfcom (manufactured by Tokyo Seimitsu Co., Ltd.).

[0093] When such a writing board sheet was attached to a wall surface, characters and pictures were drawn on the sheet using a writing instrument as shown in Fig. 1 in which black ink of the following formulation was absorbed into the ink portion. It was possible to draw without blurring, unevenness, etc. In addition, even when writing was performed early, it was possible to draw without blurring and unevenness.

<Prescription of Black Ink> Distilled water 1000 ml Ethanol 5 ml Hydroxyethyl cellulose 2 g Saponin 0.4 g Dye II-13 2.0 g Dye VI-1 2.5 g Dye I-3 2.2 g

The image thus obtained was a clear black image (reflection density: 2.15).

Further, the drawn character or picture is kept for 2 hours (22 ° C.).
(55% RH) When observed after standing, the drawn state was favorably maintained. When the characters and pictures in the left state are wiped with a wet tissue paper impregnated with a 1% by weight aqueous solution of sodium sulfite, the ink forming the letters and pictures on the sheet is erased, and at the same time, the ink components are removed. Moves over the wet tissue paper,
I was able to erase it neatly. It was also found that there was no surrounding dirt and there was no danger of the dye being inhaled into the respiratory system. In addition, chemicals or solvents for ink and eraser are preferable in terms of safety because they have little harm to the human body. further,
Even when the eraser touched the hand, no colored stain was produced on the hand, and at the same time, the colorless dye could be easily washed away by hand washing.

Example 2 In Example 1, polyvinyl alcohol was used in place of hydroxyethyl cellulose of the black ink, but the same result as in Example 1 was obtained.

Example 3 A black ink was prepared in the same manner as in Example 1 except that the combination of the dyes was changed as follows and used in the same manner as in Example 1. A clear black image was obtained and could be erased as well.

Dye combination A Dye III-1 2.3 g Dye I-24 2.1 g Dye I-10 2.5 g Dye combination B Dye II-8 1.7 g Dye IV-1 2.3 g Dye II-17 1.9g

[Example 4] A red ink was prepared by changing the combination of the dyes in the following manner with respect to the black ink of Example 2, and used in the same manner as in Example 2. A sharp clear red image was obtained and could be erased as well.

Dye combination C Dye I-6 1.9 g Dye I-9 2.1 g Dye combination D Dye VI-3 3.9 g Dye combination E Dye VI-7 2.4 g Dye I-2 2.1 g

Example 5 A blue ink was prepared according to the following formulation and used in the same manner as in Example 1. However, a clear blue image as good as that in Example 1 was obtained and erased similarly. Was completed.

<Prescription of Blue Ink> Distilled water 1000 ml Ethanol 6 ml Polyethylene glycol 15 ml Sorbitan monolaurate 0.6 g Dye II-31 2.3 g

Example 6 A blue ink was prepared in the same manner as in Example 5 except that the combination of dyes was changed as follows, and used in the same manner as in Example 5. An image was obtained and could be erased as well.

Dye Combination F Dye II-38 1.1 g Dye VI-3 1.1 g Dye Combination G Dye III-3 2.6 g

Example 7 A green ink was prepared in the same manner as in Example 5 except that the combination of the dyes was changed as follows and used in the same manner as in Example 5. An image was obtained and could be erased as well.

Dye combination H Dye III-7 2.1 g Dye combination I Dye III-6 0.9 g Dye I-4 1.2 g Dye combination J Dye II-4 1.4 g Dye II-1 1.1 g

Example 8 An orange ink was prepared in the same manner as in Example 5 except that the combination of the dyes was changed as follows.
It was used in the same manner as in Example 5, but as in Example 5, a good clear orange image was obtained and could be erased in the same manner.

Dye combination K Dye I-3 2.5 g Dye combination L Dye I-11 3.0 g Dye combination M Dye II-30 2.4 g

Example 9 In Examples 1 to 8, the same operation was performed except that characters and pictures were drawn on a commercially available white board. However, a good clear image was obtained according to the color of the ink. Obtained and could be erased as well.

[0111]

According to the present invention, even if writing is performed quickly on a white board or the like, no blurring or unevenness occurs.
The written image can be completely erased, and the surroundings are not stained and there is no health problem.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a writing instrument for ink of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Writing implement 11 Ink part 12 Writing part 13 Writing implement support part 14 Cap part 15 Refill cap part

Claims (6)

[Claims] 1. A writing board having an ink receiving layer,
Writing is performed using an ink in which one or more dyes selected from methine dyes and azomethine dyes are dissolved in water, and the written image is erased by an eraser containing at least one reducing agent and water. How to write and erase. 2. The ink receiving layer has a glossiness of 1 to 60 on its surface.
And the contact angle of the surface with water is 50
2. The writing and erasing method according to claim 1, wherein the angle is in the range of -80 degrees. 3. The method according to claim 1, wherein at least one dye selected from methine dyes and azomethine dyes is dissolved in water.
Ink used for writing and erasing methods. 4. The ink according to claim 3, which contains a water-soluble polymer and / or a surfactant. 5. The ink according to claim 4, wherein the dye is selected from the compounds represented by formulas (I) to (VI). Embedded image Wherein A ¹ and A ² each represent an acidic nucleus, A ³ represents a phenol nucleus, a naphthol nucleus or an acidic nucleus, B ¹ represents a basic nucleus, and B ² represents an onium of a basic nucleus. , Q
Represents an aryl group or a heterocyclic group. L ¹ , L ² and L
³ represents a methine group, i is an integer of 0 to 2, j
And p are each an integer of 0 to 3, q is an integer of 0 to 4, and r is 1 or 2. ] 6. An eraser for use in the writing and erasing method according to claim 1, comprising at least one reducing agent and water.