WO2014142014A1 - Color-fadable water-based ink composition - Google Patents

Abstract

[Problem] To provide a color-fadable water-based ink composition which can exhibit satisfactory covering performance even when printed and written on paper, cloth or the like, is visible clearly, and can be erased without leaving the color thereof. [Solution] A color-fadable water-based ink composition comprising: a coloring agent prepared by coloring fine resin balls with a color-developing substance; and heat-melting particles each having a larger particle diameter than that of the coloring agent.

Description

Decolorizable water-based ink composition

The present invention relates to an ink composition that is decolored by being heated. .

An ink composition for inkjet recording containing colored fine particles is known as described in Patent Document 1, but such an ink composition does not positively decolorize from the viewpoint of use.
Also, a water-based ink composition that can be decolored by heating, containing a colorant formed by coloring fine resin spheres with a colorant and at least one selected from water-soluble amino acids or salts thereof and derivatives thereof is also patented. Known as described in Document 2.
Furthermore, a water-based ink containing a colorant formed by coloring resin spherical fine particles with a colorable substance and decolored by heating is disclosed in Patent Document 3 using one or more vinyl monomers as a raw material. An emulsion polymer that is colored by containing a color former and a developer is known as described in Patent Document 4.

According to these ink and other compositions and resin particles, it can be surely decolored by heating or the like, and further decolorized at low temperature by selecting a color developing compound or decoloring agent. It is also possible.
However, for example, printing and handwriting before decoloring are not sufficiently concealed, and there is a problem that the surface can be seen through depending on the color and brightness of the printed or written object. For this reason, it may be difficult to clearly visually recognize the print or handwriting.

JP 2003-73598 A JP 2003-246944 A JP 2002-294104 A JP 2003-221405 A

The problem to be solved by the present invention is directed to glass, resin, paper, cloth, etc., and has sufficient concealing ability even when printed and written on these, and can be surely seen, and An object of the present invention is to provide a decolorizable water-based ink composition that can be erased without color residue.

The present invention is an invention having the following configuration in order to solve the above problems.
1. A decolorizable water-based ink composition comprising a colorant obtained by coloring fine resin spheres with a colorant and heat-meltable particles having a particle diameter larger than that of the colorant.
2. The microresin sphere is a polymer comprising at least one monomer selected from acrylonitrile, styrene, acrylic acid, methacrylic acid, methyl acrylate, and methyl methacrylate as a constituent unit, or an eraser described in 1. Color water-based ink composition.
3. 3. The decolorizable water-based ink composition according to 1 or 2, wherein the color former is a leuco dye.
4). 4. The decolorizable water-based ink composition according to any one of 1 to 3, wherein the heat-meltable particles are polyethylene wax particles.
5. 5. The decolorizable water-based ink composition according to any one of 1 to 4, wherein the fine resin spheres are colored in a state where the leuco dye and the developer are reacted to cause color development.
6). 6. The decolorizable water-based ink composition according to any one of 1 to 5, wherein the color developer that develops the leuco dye is a compound having a phenolic hydroxyl group or a compound having a phosphate group.
7). 7. The decolorizable water-based ink composition according to any one of 1 to 6, wherein the average particle size of the colorant is 1 μm or less and the average particle size of the heat-meltable particles is 1 μm or more.
8). The decolorizable water-based ink composition according to any one of 1 to 7, which is used for writing instruments.
9. The decolorizable water-based ink composition according to any one of 1 to 7, which is for printing.

According to the present invention, by containing heat-meltable particles having a particle diameter larger than that of the colorant in the decolorizable water-based ink composition, sufficient concealability can be achieved even when printed or written on paper or cloth. Thus, it is possible to obtain a decolorizable water-based ink composition that can be surely visually recognized and can be erased without remaining color.

Each component contained in the decolorizable water-based ink composition of the present invention will be described below.
(Coloring agent)
The colorant used in the present invention is obtained by coloring fine resin spheres with a coloring substance.
The fine resin sphere is a resin particle dispersion obtained by suspension polymerization or emulsion polymerization, or a dispersion obtained by dispersing resin particles obtained by polymerization by other known means, and a coloring substance. Mixing with an anion activator aqueous solution such as sodium dodecylbenzene sulfonate, POE alkyl ether sodium sulfate, alkyl diphenyl ether disulfonic acid soda, etc., in which pigments and dyes are dispersed, and further adding an anionic activator or nonionic activator as necessary. Further, after stirring and cooling to room temperature and filtering, it is obtained as an emulsion of colored resin spheres.
Here, the resin constituting the fine resin sphere is not particularly limited, but a resin obtained by polymerizing a monomer having an unsaturated bond is preferable.
The monomer constituting such a resin is a known addition polymerizable monomer such as (meth) acrylic acid, (meth) acrylic acid alkyl ester, acrylonitrile, styrene, and preferably acrylonitrile, styrene, acrylic It is at least one monomer selected from acid, methacrylic acid, methyl acrylate, and methyl methacrylate.
In the present invention, the average particle diameter of the colorant is preferably 1.0 μm or less, more preferably 0.8 μm or less. If it exceeds 1.0 μm, there is a possibility that the heat-melting particles having a particle diameter larger than that of the colorant cannot be sufficiently erased.
The content of the fine resin spheres in the decolorizable water-based ink composition is 1.0 to 30% by weight, preferably 2 to 20% by weight in terms of solid content. If it is less than 1.0% by weight, sufficient color development cannot be achieved, and if it exceeds 30% by weight, no further effect can be expected in terms of color density.

(Coloring substance)
As the color-forming substance that is a dye and a pigment for coloring the emulsion polymer, general materials can be used. Specifically, the color index number (CI) indicates BASIC YELLOW 1, 2, 11 , 28, 35, 36, 40, 50, BASIC ORANGE 2, 14, 15, 21, 22, 30, 32, 33, 34, BASIC RED 1, 2, 9, 12, 13, 14, 15, 17, 18 , 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40, BASIC VIOLET 1, 3, 7, 10, 14, 15, 16, 21, 25, 26, 27 , 28, BASIC BLUE 1, 3, 5, 7, 9, 19, 21, 22, 24, 25, 26, 28, 29, 40, 41, 44, 45, 47, 54, 58, 59, 60, 64 , 65, 66, 67, 68, 93, BASIC GREEN 1, 4, 6, BASIC BROWN 1, 11, 12, BASIC BLACK 2, 8, ACID YELLOW 3, 7, ACID RED 52, 77, 87, 92, ACID BLUE 9, DISPERSE YELLOW 5, 12, 64, 82, DISPERSE ORANGE 11, 13, 29, 73, DISPERSE RED 54, 58, 60, 88, 92, 127, DISPERSE BLUE 7, 56, 60, 73, 81, 91, DIRECT YELLOW 12, 44, 85, 142, DIRECT ORANGE 8, 26, 79, 83, 89, DIRECT RED 4, 9, 23, 31, 81, DIRECT BLUE 22, 71, 78, 86, 89, 90, DIRECT REEN 6, 59, 80, FLUORESCENT BRIGHTENING AGENT 55, FLUORESCENT BRIGHTTENING WWHITE WS 52, FLUORESCENT 112, 162, SOLVENT YELLOW 25, 33, 44, 93, 116, SOLVENT BLUE 5, 35, 83, SOLVENT GREEN 3, 7, PIGMENT YELLOW 1,147, PIGMENT RED 53, 57, 249, 250, 251, PIGMENT GREEN 7, PIGMENT BLUE 15, and the like. However, it is not limited to these dyes and pigments. The dye and / or pigment can be used in an amount of 0.01 to 20% by weight, preferably 0.1 to 15% by weight, based on 100 parts by weight of the polymer solid content of the emulsion polymer. When the content exceeds 20% by weight, the emulsion polymer and unbound dyes and / or pigments increase, and the water resistance of the ink composition decreases. When the content is less than 0.01% by weight, the coloring becomes light.
Among them, a leuco dye is preferable, and the leuco dye (color former) is not limited as long as it reacts with an electron accepting compound (developer) and develops a color, and a known or commercially available one may be used. it can. For example, the following compounds are suitable, and these can be used alone or in combination of two or more.

(A) Fluoranes 2 ′-[(2-chlorophenyl) amino] -6 ′-(dibutylamino) -spiro [isobenzofuran-1 (3H), 9 ′-(9H) xanthen] -3-one, 3 -Diethylamino-6-methyl-7-chlorofluorane, 3-dimethylaminobenzo (a) -fluorane, 3-amino-5-methylfluorane, 2-methyl-3-amino-6,7-dimethylfluorane, 2-Bromo-6-cyclohexylaminofluorane, 6 '-(ethyl (4-methylphenyl) amino-2'-(N-methylphenylamino) -spiro (isobenzofuran 1 (3H), 9 '-(9H) Xanthene) -3-one, 3,6-diphenylaminofluorane, etc .;
(B) Fluorenes: 3,6-bis (diethylamino) fluorene spiro (9,3 ′)-4′-azaphthalide, 3,6-bis (diethylamino) fluorene spiro (9,3 ′)-4 ′, 7 ′ -Diazaphthalide etc .;
(C) Diphenylmethanephthalides: 3,3-bis- (p-ethoxy-4-dimethylaminophenyl) phthalide and the like;
(D) Diphenylmethane azaphthalides ... 3,3-bis- (1-ethoxy-4-diethylaminophenyl) -4-azaphthalide and the like;
(F) Indolylphthalides: 3,3-bis (n-butyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide etc;
(G) Phenylindolylphthalides: 3- (1-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide and the like;
(H) Phenylindolyl azaphthalides 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- [2- Ethoxy-4- (N-ethylanilino) phenyl] -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide and the like;
(I) styrylquinolines: 2- (3-methoxy-4-dodecoxystyryl) quinoline and the like;
(J) Pyridines: 2,6-diphenyl-4- (6-dimethylaminophenyl) pyridine, 2,6-diethoxy-4- (4-diethylaminophenyl) pyridine and the like;
(K) quinazolines: 2- (4-N-methylanilinophenyl) -1-phenoxyquinazoline, 2- (4-dimethylaminophenyl) -4- (1-methoxyphenyloxy) quinazoline and the like;
(L) Biskinazolines: 4,4 ′-(ethylenedioxy) -bis [2- (1-diethylaminophenyl) quinazoline], 4,4 ′-(ethylenedioxy) -bis [2- (1-di -N-butylaminophenyl) quinazoline] and the like;
(M) Ethylenophthalides: 3,3-bis [1,1-bis- (p-dimethylaminophenyl) ethyleno-3] phthalide and the like;
(N) Ethylene azaphthalides: 3,3-bis [1,1-bis- (p-dimethylaminophenyl) ethyleno-2] -4-azaphthalide, 3,3-bis [1,1-bis- (P-dimethylaminophenyl) ethyleno-2] -4,7-diazaphthalide and the like;
(O) Triphenylmethanephthalides: Crystal violet lactone, malachite green lactone, etc .;
(P) Polyaryl carbinols: Michler hydrol, crystal violet carbinol, malachite green carbinol, etc .;
(Q) leucooramines: N- (2,3-dichlorophenyl) leucooramine, N-benzoyloramine, N-acetyloramine, etc .;
(R) Rhodamine lactams: Rhodamine β-lactam, etc .;
(S) Indolines: 2- (phenyliminoethylidene) -3,3-dimethylindoline and the like;
(T) Spiropyrans: N-3,3-trimethylindolinobenzospiropyran, 8-methoxy-N-3,3-trimethylindolinobenzospiropyran, etc .;
In addition to these, diazarhodamine lactones, xanthenes and the like can also be used in the present invention.
The content of the leuco dye can be appropriately set according to the type of the compound, etc., but in general, it is about 0.005 to 5.0% by weight in the decolorizable water-based ink composition of the present invention. It is desirable that the content be about 01 to 3.0% by weight. When the content is less than 0.005% by weight, the color density may be lowered. Moreover, when the said content exceeds 5.0 weight%, there exists a possibility that background color development may become large.

(Developer)
The developer is not limited and a known or commercially available developer can be used as appropriate. For example, the following compounds can be preferably used. These can be used alone or in combination of two or more.

(A) Phenols: bisphenol A or derivatives thereof, bisphenol S or derivatives thereof, p-phenylphenol, dodecylphenol, o-bromophenol, ethyl p-oxybenzoate, methyl gallate, phenol resin, etc .;
(B) Metal salts of phenols: metal salts of phenols such as Na, K, Li, Ca, Zn, Al, Mg, Ni, Co, Sn, Cu, Fe, Ti, Pb, and Mo;
(C) aromatic carboxylic acids and aliphatic carboxylic acids having 2 to 5 carbon atoms: phthalic acid, benzoic acid, acetic acid, propionic acid, etc .;
(D) Metal salts of carboxylic acids: sodium oleate, zinc salicylate, nickel benzoate, etc .;
(E) Acid phosphate esters: butyl acid phosphate, 2-ethylhexyl acid phosphate, dodecyl acid phosphate, etc .;
(F) Metal salt or ammonium salt of acidic phosphate esters: Na, K, Li, Ca, Zn, Al, Mg, Ni, Co, Sn, Fe, Ti, Pb, Mo, etc. of acidic phosphate esters Metal salts, etc .;
(G) Triazole compound: 1,2,3-triazole, 1,2,3-benzotriazole, etc .;
(H) Thiourea and derivatives thereof: diphenylthiourea, di-o-toluylurea, etc .;
(I) Halohydrins: 2,2,2-trichloroethanol, 1,1,1-tribromo-2-methyl-2-propanol, N-3-pyridyl-N ′-(1-hydroxy-2,2,2 -Trichloroethyl) urea and the like;
(J) benzothiazoles: 2-mercaptobenzenethiazole, 2- (4′-morpholinodithio) benzothiazole, N-tert-butyl-2-benzothiazolylsulfenamide, Zn salt of 2-mercaptobenzothiazole, and the like;

In the present invention, among these electron-accepting compounds, at least one of phenols which are compounds having a phenolic hydroxyl group and metal salts thereof can be suitably used. In particular, at least one selected from 1 (bisphenol A and derivatives thereof, and 2) bisphenol S and derivatives thereof is more preferable, most preferably 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 2,2 And at least one of -bis (4-hydroxyphenyl) propane and 1,1-bis (4'-hydroxyphenyl) -1-phenylethane.

〔Ｒは炭素数８乃至３０のアルキル基又はアルキルアリール基を示し、Ｒ’はＨ又はＲ（ＣＨ_２ＣＨ_２Ｏ）n を示し、ｎは１乃至３０の数を示す〕 Acid phosphate esters and metal salts or ammonium salts thereof are also suitable. For example, phosphate esters of polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether represented by the following general formula, for example, alkanolamine, monoethanol Amines, diethanolamines, triethanolamine salts and the like can be employed.

[R represents an alkyl group or alkylaryl group having 8 to 30 carbon atoms, R ′ represents H or R (CH ₂ CH ₂ O) n, and n represents a number of 1 to 30]

The acidic phosphate esters may be phosphate ester surfactants. Examples of such phosphate ester surfactants include saturated monooctyl phosphate, monolauryl phosphate, monostearyl phosphate, and the like. Unsaturated alkyl esters such as alkyl esters, phosphoric monooleyl esters and monolinoleyl phosphates, monophosphates having conjugated unsaturated ester groups such as monoacryloxybutyl phosphate and monomethacryloxypropyl phosphate Alkyl esters, mercaptoalkyl esters such as monocaptohexyl phosphate and monocaptododecyl phosphate, and phosphoric monoesters of chlorohexyl and hydroxyhexyl, polyoxyethylene alkyl ether phosphates Ether salts, polyoxyethylene alkyl phenol ether phosphate salt, alkyl phosphoric acid ester salts.

Examples of the acidic phosphate esters include methyl acid phosphate, dimethyl acid phosphate, ethyl acid phosphate, dier acid phosphate, methyl ethyl acid phosphate, normal- or iso-propyl acid phosphate, positive- or iso-dipropyl. Acid phosphate, methyl propyl acid phosphate, ethyl propyl acid phosphate, positive- or iso-butyl acid phosphate, positive- or iso-dibutyl acid phosphate, methyl butyl acid phosphate, ethyl butyl acid phosphate, propyl · Butyl acid phosphate, positive or iso-benchyl acid phosphate, positive or iso dibenchyl acid phosphate, positive or iso-hexyl acid phosphate Positive- or iso-dihexyl acid phosphate, positive- or iso-octyl acid phosphate, positive- or iso-dioctyl acid phosphate, positive-decyl acid phosphate, positive-didecyl acid phosphate, positive-lauryl acid phosphate, positive-di Lauryl acid phosphate, normal- or iso-cecyl acid phosphate, positive- or iso-dicesyl acid phosphate, positive- or iso-stearyl acid phosphate, positive- or iso-distearyl acid phosphate, ethylene glycol acid phosphate, glycerin acid phosphate , Allyl acid phosphate, diallyl acid phosphate, propargyl acid phosphate, dipropargyl acid phosphate, phenol acid phosphate, benzyl acid phosphate Eto, dibenzyl acid phosphate, or a cresyl acid phosphate and the like.

The phosphate ester is a monoester or a diester as shown in the above general formula, and may be a mixture thereof. Specific examples include Prisurf A212C, A210G, A207H, AL, A212C, A208B, A208S, A208F, M208B, M208F, A212E, A219B, A206K, A217E [first] Industrial Pharmaceutical Co., Ltd.], Phosphanol RE-210, RE-410, RE-710, RS-410, RB-410, RM-410, RM-510, RL-210, RD-510Y, GB-520 (Toho Chemical Co., Ltd.), etc.

The above surfactant is also effective as a salt. Salts include alkali metals (sodium, potassium, etc.), alkaline earth metals (calcium, magnesium, etc.), ammonium and amines (alkanolamines such as mono-, di- or triethanolamine, dimethylethanolamine, mono- or diisopropanol). Luamine, lower alkylamines such as methylamine and ethylamine) and two or more salts thereof. Preferred are amine salts and alkaline earth metal salts. Examples of the alkylene oxide (hereinafter abbreviated as AO) include C2 -4 AO, such as ethylene oxide (hereinafter abbreviated as EO) and / or propylene oxide (hereinafter abbreviated as PO).

Among them, long chain alkyl phosphate ester salts (normally 6 to 20, preferably 12 to 18 carbon atoms) of saturated or unsaturated higher alcohols (cetyl alcohol, stearyl alcohol, oleyl alcohol, etc.) Phosphoric acid mono- and / or diester salts such as polyoxyalkylene alkyl ethers or polyoxyalkylene alkyl aryl ether phosphate esters [AO adducts of the aforementioned saturated or unsaturated alcohols (addition mole number is usually 1 to 8) Alternatively, an AO adduct of alkylphenol or alkylnaphthol (nonylphenol, dodecylphenol, dinonylphenol, etc.) having at least one, preferably 1-2, alkyl group having 8 to 12 carbon atoms (addition mole number is usually 1 to 8). ) Mono- or diester salts of phosphoric acid such as stearyl alcohol O (5) phosphoric acid diester monopotassium salt (indicating phosphoric acid diester monopotassium salt of EO 5 mol adduct of stearyl alcohol), long chain alkylphosphonate [long chain alkyl group (normally having 6 to 6 carbon atoms) 24, preferably 12 to 20 alkyl groups (including alkenyl groups) such as phosphonates or monoester salts having a cetyl group, an oleyl group, etc.) and the like. Among them, preferred are a long-chain alkyl phosphate ester salt and a polyoxyalkylene long-chain alkyl phosphate ester salt.

The content of the developer can be appropriately set according to the type of the compound and the like, but is generally about 0.05 to 98% by weight in the decolorizable water-based ink composition of the invention, particularly 0.5 to It is desirable that the content be 77% by weight. When the content is less than 0.05% by weight, the color density may be lowered. Moreover, when the said content exceeds 98 weight%, there exists a possibility that background coloring may become large. In the present invention, in relation to the leuco dye, the developer is preferably 0.1 to 50 parts by weight, particularly 0.5 to 20 parts by weight, with respect to 1 part by weight of the leuco dye.

(Hot-melting particles)
The meltable particles in the present invention do not have a film-forming property when dispersed in a solvent, cause scattering of reflected light due to the particle shape, and the handwriting and printing by the decolorizable water-based ink composition become opaque. Thereby, the handwriting by the decolorizable water-based ink composition of the present invention also has an opaque property without film forming property. The fusible particles also function as a decolorizer for the colorant.
When the handwriting or the like is melted beyond the melting point of the fusible particles, the fusible particles exhibit fluidity and form a film on the surface of the handwriting portion, and the irregular reflection due to the particles is eliminated and the particles become transparent.
Thus, since the handwriting before heating by the decolorizable water-based ink composition according to the present invention has a concealing property due to the presence of the meltable particles, the handwriting is sufficiently colored with the colorant. When the film is heated to form a film, the particles melt and form a film, so that the concealability is lost. In addition, when the heating temperature is the same as the melting temperature or higher than the temperature at which the coloring substance is decolored, the colorant is decolored by the heating temperature. Therefore, the handwriting after heating becomes colorless and transparent, and is in a state similar to a state where no handwriting is visually observed.
For example, heat-fusible particles such as polyethylene dispersed in water have no film-forming property at room temperature and are opaque, but have the property of obtaining a transparent film when heated. That is, the heat-meltable particles generally have no film-forming property at room temperature, and their presence can be visually recognized. However, since the glass transition point, melting point, and flow temperature are 95 to 120 ° C., they can be dissolved by applying heat such as an iron. It flows and becomes a transparent film.

When the decolorizable water-based ink composition of the present invention is used as a chacopen, the ink composition contains heat-fusible particles having a film forming temperature higher than room temperature, so that it is colored with a colorant during writing. Even after the handwriting has been dried, the colorant is colored and the dough surface is concealed by the remainder of the heat-meltable particles having a particle size larger than that of the colorant. A white color that is almost the same as or a colored color appears.
In addition, no unpleasant odor is produced even when heated by ironing or the like. Further, when heated by ironing or the like, a film is formed to become a transparent film, and the appearance is erased by erasing the color-forming substance, so that it can be corrected and marked any number of times. In addition, since these are water-based ink compositions, they are well dispersed in water, so that they are well washed off with water.
Such heat-meltable particles in the present invention are not particularly limited, but polyethylene wax can be suitably used. Further, those having a melting point of 85 ° C. to 130 ° C. and being stably dispersed in water are preferable.

The average particle diameter of the hot-melt particles having a particle diameter larger than that of the colorant is not particularly limited, but is 1.0 μm or more, and preferably 1.0 to 10 μm. If the particle size is less than 1.0 μm, the hiding power cannot be sufficiently exhibited, and it becomes difficult to sufficiently check the handwriting and the like, and it is melted by heating to form a film on the surface of the cloth. Even in this case, it is difficult to reliably form a film.

The polyethylene particles are desirably formulated as an aqueous emulsion or aqueous dispersion.
In this case, it is possible to use a commercially available aqueous emulsion or aqueous dispersion as it is. For example, finely divided polyethylene particles are introduced into an aqueous solution containing a dispersant while stirring, and then it is added. It is also possible to use an aqueous dispersion by applying it to a disperser.

When using an aqueous emulsion or aqueous dispersion of polyethylene particles, trade names “AC polyethylene 629” and “AC polyethylene 655” manufactured by Allied Chemical Co., Ltd. can be exemplified. Further, trade names “polyethylene wax CJ-137” and “polyethylene wax CJ-71” manufactured by Koyo Chemical Co., Ltd. can be exemplified. Among them, trade name “AC polyethylene 655” manufactured by Allied Chemical Co., Ltd. and trade name “polyethylene wax CJ-137” manufactured by Koyo Chemical Co., Ltd. are preferable.

The amount of the fusible particles used is not particularly limited, but it is sufficient if the solid content in the decolorizable water-based ink composition is 5 to 35% by weight, preferably 10 to 25% by weight. It is. When the amount of the fusible particles used is less than 5% by weight in solid amount, the whiteness of the handwriting is lost. On the other hand, if the solid content exceeds 35% by weight, the viscosity is increased and the outflow of ink to the fabric is deteriorated, the writing property is lowered, and it is not necessarily suitable as a ballpoint pen.

In addition, when using fine powder of polyethylene particles such as trade name “AC polyethylene” manufactured by Allied Chemical Co., as described above, it is preferable to use a dispersant. Examples of the dispersant include polyoxyethylene nonylphenyl ether, polyoxyethylene alkyl ester, polypropylene glycol polyethylene glycol block copolymer, polyoxyethylene polyoxypropylene block copolymer, and alkylbenzene sulfonic acid soda.

(Aqueous solvent)
As the aqueous solvent used in the decolorizable water-based ink composition of the present invention, water or a mixed solvent of water and a water-soluble organic solvent can be used. An aqueous solvent derived from the above acrylic silicone resin emulsion is also blended in the ink composition.
The water-soluble organic solvent in the present invention may be a known one, and the water-soluble organic solvent can be used as an ink drying inhibitor or wetting agent. The water-soluble organic solvent is not particularly limited, but glycols such as ethylene glycol, diethylene glycol, and propylene glycol, glycol ethers such as ethylene glycol monomethyl ether, carbitols such as diethylene glycol monomethyl ether, glycerin, and triglyceride. Examples include methylolpropane. A water-soluble organic solvent can be used individually or in combination of 2 or more types. By using such an aqueous organic solvent, it is possible to prevent the pen tip from drying when used as a writing instrument.

In the ink composition of the present invention, the use amount of the entire aqueous solvent including the solvent derived from the production of the fine resin spheres is 1 to 90% by weight, preferably 5 to 85% by weight with respect to the entire ink composition. %.
In the present invention, if the blending amount of the aqueous solvent exceeds 90% by weight, the viscosity of the ink composition becomes too low, so it becomes difficult to control the ink composition that flows out when used as a writing instrument, and the handwriting becomes too thin. As a result, the scratch resistance deteriorates and the color development becomes lighter. In addition, in spite of the necessity, when the aqueous solvent is not sufficiently blended, the ink composition becomes too viscous to deteriorate the ink flowability when used as a writing instrument.

(Method for producing decolorizable water-based ink composition)
As a specific method for producing the decolorizable water-based ink composition of the present invention, the dye and / or pigment is added to an aqueous solution of an anionic active agent such as sodium dodecylbenzene sulfonate, sodium POE alkyl ether sulfate, sodium alkyl diphenyl ether disulfonate, Further, if necessary, a desensitizer for adjusting the discoloration temperature is dispersed, and a dispersion of the above-mentioned fine resin spheres and, if necessary, an anionic activator and a nonionic activator are added, and further 80 ° C. A method of obtaining an emulsion of the colorant by cooling to room temperature and filtering after stirring for 1 hour and then stirring can be employed.

As a method for obtaining the color erasable water-based ink composition of the present invention by employing this colorant, one or more of the above colored body emulsions are heat-meltable with a particle diameter larger than that of the colorant. Dispersing liquid containing particles, ion-exchanged water, preservative, etc., and optionally mixing with a solvent containing a water-soluble organic solvent such as alcohol or glycol, and stirring this for about 1 hour, the intended decolorizable water-based ink A composition is obtained.
The colorant can be used in an amount of 2 to 40% by weight (as solid content), preferably 3 to 28% by weight, based on the total decolorable water-based ink composition. When it exceeds 40% by weight, the viscosity becomes high and the writing property is lowered, and when it is less than 2% by weight, the color becomes light.

When the water-soluble organic solvent is used, the amount used can be 10 to 60% by weight in the total ink composition, and preferably 20 to 50% by weight. If it exceeds 60% by weight, drying of the handwriting is delayed and bleeding is severe, and if it is less than 20% by weight, drying of the nib is accelerated. The emulsion polymer emulsion, colored body emulsion and ink composition in which the resin particles are dispersed naturally contain an appropriate amount of water necessary for dispersing the components.
The decolorizable water-based ink composition of the present invention may contain components other than those described above as necessary. Specifically, lubricants, wetting agents, rust preventives, antiseptics, antifungal agents, antifoaming agents, leveling agents, anti-aggregation agents, pH adjusters, water-soluble organic solvents, surfactants, and the like are added. Good.

(Coloring agent)
In the present invention, the decolorizable water-based ink composition may further contain a pigment or a dye separately from the above dye.
For example, as organic pigments and dyes, known organic compounds such as phthalocyanine, azo, quinacrine, anthraquinone, dioxane, indigo, thioindigo, perinone, perylene, indolenone, azo-azomethine Pigments and dyes can be used.
Examples of inorganic pigments that can be used include titanium dioxide, carbon black, alumina silica, talc, aluminum powder, bronze powder and other metal powder pigments; fluorescent pigments; pearl pigments; and glitter pigments.

The content of these pigments and dyes in the decolorizable water-based ink composition of the present invention is 0.5 to 35% by weight, preferably 1.0 to 30% by weight. If it exceeds 35% by weight, the viscosity of the ink composition becomes too high, and when it is used as a writing instrument, the ink outflow is deteriorated. If it is less than 0.5% by weight, the ink composition is not sufficiently colored, Color developability and concealment deteriorate.

(Dispersant)
In the present invention, for the purpose of stabilizing the dispersion of the contained pigment, a dispersant having excellent solubility in water is added to the ink composition.
As such a dispersant, a known dispersant can be used, for example, one or more of a styrene acrylic resin, a styrene resin and an acrylic resin. As such a dispersant, for example, Jonkrill J-62, Jonkrill HPD-96, Jonkrill 70 (BASF Japan) and the like can be used.
The content of the dispersant in the decolorizable water-based ink composition of the present invention is 0.1 to 20% by weight, preferably 0.5 to 15% by weight, based on the entire ink composition. The content can be determined according to the amount of the pigment.
When the content of the dispersant exceeds 20% by weight, the ink spillability when used as a writing instrument deteriorates. When the content is less than 0.1% by weight, the dispersibility of the colorant decreases and the handwriting is scratched against the substrate. It will be inferior.

(Other additives)
If necessary, other additives may be added to the decolorizable water-based ink composition of the present invention. Other additives are not particularly limited, but conventional additives include rust preventives such as benzotriazole, tolyltriazole, dicyclohexylammonium nitrate, benzoisothiazoline antiseptic and antifungal agents, pentachlorophenol Antiseptic / antifungal agents, cresol antiseptic / antifungal agents, propylene glycol antiseptic / antifungal agents, antiseptic / antifungal agents such as iodine-based antiseptic / antifungal agents, alkylsulfosuccinic acid-based surfactants, wetting agents, antifoaming agents, A leveling agent, an anti-aggregation agent, a pH adjuster, etc. are mentioned.

(Use of ink composition)
The ink composition of the present invention is suitably used as a water-based ballpoint pen-shaped chaco, but the ink composition of the present invention is not limited to such applications, and can be erased from, for example, T-shirts, notebooks, drawing paper, books, etc. It can also be used as a simple pen and can be applied to writing instruments for a wide range of uses. For example, an ink storage part such as a marker or a pen can be filled and written on the surface of glass, earthenware, resin, or the like via the tip. Further, it can be printed on paper, cloth, glass, resin or the like by silk printing or the like.

 

 

Examples of the present invention are shown below, but the present invention is not limited to these examples.
(Example)

Acrylic micro resin sphere emulsion:
4 parts of dodecylbenzenesulfonic acid and 0.2 parts by weight of potassium persulfate are dissolved in 65.8 parts by weight of water, and 6 parts by weight of acrylonitrile, 4 parts by weight of acrylic acid, 12 parts by weight of methyl acrylate, and 8 parts by weight of ethyl methacrylate. Was added dropwise to raise the temperature to 80 ° C. to carry out emulsion polymerization. Thereafter, it was cooled to room temperature to obtain an emulsion of fine resin spheres.
Subsequently, rhodamine β was dispersed in an aqueous solution prepared by dissolving 1.5 parts by weight of sodium dodecylbenzenesulfonate and 3 parts by weight of sodium POE alkylteter sulfate in 34.4 parts by weight of water. To this, the emulsion of fine resin spheres obtained in the above step and POE nonylphenyl ether were added, further heated to 80 ° C., stirred for 1 hour, cooled to room temperature, and filtered to obtain acrylic fine resin spheres. An emulsion was obtained. The solid content was 30% by weight, the pH was 4.0, and the average particle size was 0.12 μm.

Red 500: leuco dye made by Yamada Chemical Industry Red 520: leuco dye made by Yamada Chemical Industry Red DCF: leuco dye made by Hodogaya Chemical Industry Pink DCF: leuco dye Vermilion made by Hodogaya Chemical Industry DCF: leuco dye Red 40 made by Hodogaya Chemical Industry : Yamamoto Chemical Industries leuco dye Red I-6B: BASF leuco dye Phosphanol RM710: Toho Chemical Industries phosphoric acid surfactant New Coal 565-PS: Daiichi Kogyo Seiyaku phosphoric acid surfactant Berex NBL : Condensed naphthalene surfactant micro flat CJ137 manufactured by Kao: Polyethylene 40 wt% dispersion (average particle size 3.4 μm) manufactured by Koyo Chemical Co., Ltd.
PVP K30: 10% aqueous solution manufactured by ISP Japan

Test method Concealment: A ballpoint pen was filled with an ink composition and written on black drawing paper, and the visibility was evaluated by three stages visually.
○: Visible clearly △: Thin but visible ×: Not visible

An iron erasable ballpoint pen is filled with an ink composition and written on a white paper, and the visibility is evaluated by three stages visually.
○: Not visible △: Thin but visible ×: Visible clearly

According to Examples 1 to 14, by using together the heat-meltable particles having a particle diameter larger than that of the colorant, the handwriting when writing with the decolorizable water-based ink composition is the color of the underlying black drawing paper. It was sufficiently concealed.
In addition, after heating and decolorizing the colorant, the handwriting could not be visually recognized, and only the underlying black color could be confirmed.
On the other hand, according to Comparative Examples 1 to 6, since no hot-melt particles having a particle size larger than that of the colorant are used in combination, the handwriting when writing with the decolorizable water-based ink composition is the black paper on the background I couldn't conceal the color and couldn't confirm the handwriting. Further, after the colorant is decolored by heating, it can be seen that although the handwriting is thin, it can be confirmed or clearly visibly visible. This indicates that in the present invention, the hot-melt particles having a large particle size functioned as a decoloring agent.

Claims (9)

A decolorizable water-based ink composition comprising a colorant formed by coloring fine resin spheres with a colorable substance and heat-meltable particles having a particle diameter larger than that of the colorant. The fine resin sphere is composed of a polymer containing at least one monomer selected from acrylonitrile, styrene, acrylic acid, methacrylic acid, methyl acrylate, and methyl methacrylate as a constituent unit, or a polyolefin. Decolorizable water-based ink composition. The decolorizable water-based ink composition according to claim 1 or 2, wherein the color developing substance is a leuco dye. 4. The decolorizable water-based ink composition according to claim 1, wherein the heat-meltable particles are polyethylene wax particles. The decolorizable water-based ink composition according to any one of claims 1 to 4, wherein the fine resin spheres are colored in a state where the leuco dye and the developer are reacted to cause color development. The decolorizable water-based ink composition according to any one of claims 1 to 5, wherein the developer that develops the leuco dye is a compound having a phenolic hydroxyl group or a compound having a phosphate group. The decolorizable water-based ink composition according to any one of claims 1 to 6, wherein the average particle diameter of the colorant is 1 µm or less and the average particle diameter of the heat-meltable particles is 1 µm or more. The decolorizable water-based ink composition according to any one of claims 1 to 7, which is used for writing instruments. The decolorizable water-based ink composition according to any one of claims 1 to 7, which is used for printing.