JP2003268248A - Suspension polymer having color developing compound and ink and toner utilizing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suspension polymer which contains a leuco dye as the color developing compound, can utilize not only heating but also an organic solvent as the decoloring means, excels in water resistance and light resistance and, in addition, is uniform in the particle diameter and the particle shape, and spherical. <P>SOLUTION: The suspension polymer develops color by containing at least a leuco dye and a developer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a suspension polymer which can be discolored or discolored by containing a color-forming compound represented by a leuco dye, and a writing instrument containing the suspension polymer. Ink and printing toner.

[0002]

2. Description of the Related Art Heretofore, an ink using a color-forming compound typified by a leuco dye has been widely known as an ink capable of being decolored or discolored. For example, JP-A-7-812
No. 36 discloses an ink using a colored compound produced by chemically reacting a colorless leuco dye and a color developer in an organic solvent. Since the ink also contains a desensitizer, characters printed using this ink are erased by the action of the desensitizer by heating. Further, JP-A-10-287081 discloses an invention of an aqueous ballpoint pen using an ink in which a leuco dye and a color developer are heated and melted, allowed to cool, and then pulverized into a colorant. A writing line drawn by this water-based ballpoint pen is decolored by being heated after being immersed in a stripping solution containing water containing a desensitizing agent as a main component. However, since these inks are decolorized only by heating, the decoloring means are limited. Further, since the leuco dye and the color developer are in direct contact with water which is a solvent, the leuco dye and the color developer are faded over time, and the light resistance is low due to direct exposure to sunlight.

Further, the leuco dye described in JP-A-10-88046 is kneaded with a resin together with a developer and a decolorizer, and therefore has a relatively high light resistance due to the coating effect of the resin. Furthermore, the ink containing this kneaded material,
When the resin was dissolved using an organic solvent, the decolorizing agent was preferentially chemically bonded to the color developing agent, and thus the decoloring was possible not only by heating but also by the organic solvent. However, since the ink is obtained by finely pulverizing the kneaded product with a jet mill to obtain a colorant, the colorant obtained has a relatively large particle size and is not uniform, and is used as an ink for writing instruments. In that case, the writing feel becomes poor, and when used as a toner, the printed image quality becomes rough. Further, since the particle shape and particle diameter of the colorant are not uniform, when used in an ink, unless the viscosity of the ink is carefully adjusted, the dispersibility of the liquid in the ink is inferior. There is a problem that the charge amount of the particles becomes uneven and the image quality is deteriorated.

[0004]

Therefore, in order to solve the above-mentioned problems, the first object of the present invention is to utilize not only heating but also an organic solvent as a decoloring means when a color-forming compound is used. And a light-fast suspension polymer having a relatively uniform particle size and particle shape and a spherical shape. Another object of the present invention is to provide an ink and a printing toner for a writing instrument or the like containing the suspension polymer.

[0005]

The suspension polymer which achieves the above-mentioned object of the present invention is characterized in that it develops a color by containing at least a leuco dye and a developer. Further, the suspension polymer which achieves the object of the present invention, a mixture containing at least a vinyl-based monomer, a leuco dye and a developer is added to an aqueous medium containing a dispersion stabilizer and having a pH of 4 to 7, It is characterized by being obtained by uniformly stirring and dispersing, then adding a polymerization initiator and carrying out suspension polymerization. The ink and the toner according to the present invention are characterized by containing the suspension polymer. At this time, the ink may contain a decoloring agent composed of a basic compound containing a nitrogen atom. As a result, the ink can be easily decolorized or discolored by adding an organic solvent or heating.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail. First, the monomer that can be used as a raw material of the suspension polymer of the present invention will be described in detail. The monomer that can be used as the raw material of the suspension polymer of the present invention may be any monomer as long as it is a monomer that is usually used for suspension polymerization, but is preferably a non-polar or small-polar monomer. Is good. This is because when the monomer has a large polarity, it acts as a Lewis base on the leuco dye, and inhibits the leuco dye from acting as a color developer to develop color. Therefore, the monomer used in the present invention is preferably a vinyl monomer having a small polarity, and for example, styrene, nitrostyrene, chlorostyrene, hydroxyethyl methacrylate and the like are particularly preferable. These monomers may be used alone or in combination of two or more.

Next, the color-developing compound and the color developer according to the present invention contained in the suspension polymer obtained from the above monomers will be described in detail. The color-forming compound used in the present invention causes a color reaction such as a redox reaction or an acid-base reaction,
In particular, it is a compound that reversibly changes from colorless to colored, and specific examples thereof include phenolphthalein, but it is typically a leuco dye. This leuco dye is, for example, a compound having a lactone ring in the molecule such as triphenylmethane type, diphenylmethane type, spiropyran type, fluorane type, rhodamine lactam type, etc., and one or more of them are mixed and used. can do.
Examples of these compounds include "CVL" and "Gr".
een DCF "," Vermilion DCF ",
"Red DCF", "Orange DCF", "T"
H-106 "," TH-107 "," TH-108 ",
"TH-109", "CF-51", "D.L.M.
B. "(Above, product name by Hodogaya Chemical Co., Ltd.)," DEBN "," RED 500 "," RED
520 ”,“ S-205 ”,“ Black 100 ”,
"Black 202", "Black 305", "E
TAC ”,“ Blue 220 ”,“ NIR Blac ”
k 78 ”,“ Green 300 ”,“ Pink 5 ”
35 "(above, product name of Yamada Chemical Industry Co., Ltd.),
"ODB", "ODB-2", "ODB-7", "Bl"
ack-15 ”,“ Black-173 ”,“ Blue
-63 "," Blue-502 "," Green-4 "
0 "," Red-3 "," Red-40 "," MNS "
P ”,“ LCV ”,“ GN-2 ”,“ GN-169 ”,
"GN-118" (above, product name of Yamamoto Kasei Co., Ltd.), "PERGASCRIPT RED I-6
B "," PERGASCRIPT Green I-2 "
GN ”(these are trade names of Ciba Specialty Chemicals Co., Ltd.) and the like can be used.

The color developer used in the present invention acts on the color-forming compound to develop the color-forming compound. Examples of the developer for leuco dyes include phosphoric acid, phosphoric acid monoester,
A compound having a phosphoric acid group in the molecule such as phosphoric acid diester, or phenolic in the molecule such as hydroxyacetophenone type, hydroxybenzophenone type, gallic acid ester type, benzenetriol type, bisphenol type, triphenol type, cresol type It is a compound having a hydroxyl group, and one kind or a mixture of two or more kinds thereof can be used. Among these compounds, as the compound having a phosphoric acid group, a monoalkyl phosphoric acid ester, a dialkyl phosphoric acid ester, a polyoxyethylene monoalkyl phosphoric acid ester, a polyoxyethylene dialkyl phosphoric acid ester, or the like can be used. Examples of the compound having a phenolic hydroxyl group include dihydroxyacetophenone, trihydroxyacetophenone, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, dihydrobenzoic acid, bisphenol, hydroxyphenylalkyl-benzotriazole, methylenetris-p-cresol. , Gallic acid alkyl ester and the like can be used. Here, the compound having a phosphoric acid group or a phenolic hydroxyl group, as an alkyl group, a methyl group,
It has an ethyl group, a propyl group, a butyl group, a nonyl group, a lauryl group, an oleyl group, a stearyl group and the like. Specific examples of the compound having a phosphate group include, for example, phosphanol series (manufactured by Toho Chemical Industry Co., Ltd., trade name), Prisurf series (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name), Newcol 565. -PS (manufactured by Nippon Emulsifier Co., Ltd., trade name) and the like can be mentioned. still,
Since preparation of the suspension polymer requires comparatively vigorous stirring, the developer is preferably a compound which causes less foaming upon stirring, that is, a compound which does not act as a surfactant. Therefore, among the above-described developers, phosphoric acid, as the developer according to the present invention,
Alternatively, a monoalkyl phosphate ester or a dialkyl phosphate ester having any one of a methyl group, an ethyl group, a propyl group and a butyl group as an alkyl group is particularly preferable.

Next, the decoloring agent according to the present invention will be described in detail. The decoloring agent is a compound used to eliminate the color of the leuco dye that has developed color by inhibiting the interaction between the leuco dye and the color developing agent. When the writing surface or the printing surface is a paper, most of the paper contains the starch having the above-described decoloring ability, and therefore the color-developing compound and the color-developing agent according to the present invention include the color-developing compound and the like. Even if the contained colorant system (for example, ink or toner) does not particularly contain a decoloring agent, decolorization by an organic solvent and heating is possible. However, when the writing surface is paper containing no starch, or glass or plastic, the color is not sufficiently erased by the organic solvent and heating. In such a case, decoloring can be performed by adding a decoloring agent separately to the colorant system.
Examples of the decoloring agent include polymers containing a nitrogen atom and basic compounds such as amino acids. As a method of incorporating the decoloring agent into the colorant system, microparticles can be formed by a method similar to the method for producing colored microparticles such as suspension polymerization method, or conventionally known microencapsulation. There is a method to isolate and use. Further, when the colorant system is a liquid composition, a method of directly adding the decoloring agent to the liquid is also possible. Among these, in the method of separating from the colored fine particles, as a decoloring agent, a compound having a basic hydroxyl group such as an alkali metal hydroxide, an alkaline earth metal hydroxide or an alkali metal alkoxide, urea and hydantoin and their Lewis base compounds having a nitrogen atom such as derivatives can be used. Further, in the method of directly adding the decolorizing agent to the liquid, since the decoloring agent is present in the liquid, the state becomes almost the same as that at the time of decoloring, and the compound having a basic hydroxyl group has a basicity of Due to its strength, the colored fine particles are erased. Further, among the Lewis base compounds, the above-mentioned urea, hydantoin, and their derivatives do not erase the color of the ink, but the decolorizing effect is extremely low even when the written or printed line is heated. On the other hand, when a basic compound such as a polymer containing a nitrogen atom is used as a decoloring agent, the color of the ink is not erased in a normal state, but an organic solvent for decolorization (hereinafter referred to as a decolorization solvent It is possible to erase the color by heating. As the basic compound which is a polymer containing a nitrogen atom having a decoloring action, a compound represented by the general formula (1) can be particularly mentioned.

[Chemical 1] [In the Formula, X and Y are arbitrary functional groups, Q is a single bond, an alkylene group, a phenylene group, or -COO-L-, -C.
The group represented by ONH-L- and -CONR-L- is shown.
Here, L and R are groups composed of hydrocarbons, and R1, R2, and R3 are groups composed of atoms selected from hydrogen, carbon, nitrogen, oxygen, and sulfur. Here, L, R, R1, R2 and R3 may be the same or different, and may have a substituent. In addition, l, m and n represent the mole percentage of each minimum constitutional unit constituting the constitutional unit represented by the general formula (1), l and m are integers from 0 to 90, and n is 0 to 100.
Represents an integer up to, and l + m + n = 100. ]

The site having an actual decolorizing ability in the above compound is a group having a nitrogen atom as a center. Also X, Y
Is an arbitrary functional group, but it is also possible to control the solubility by introducing a hydrophilic group and / or a hydrophobic group and changing the ratio thereof. Specific examples of the compound that can be used as the decoloring agent include the nitrogen atom-containing polymers represented by the structural formulas (A) to (G) below.

[Chemical 2] [N represents a positive integer. ] Here, (A) is polyvinylpyrrolidone, and (G)
Is a PUVA series (trade name, manufactured by Otsuka Chemical Co., Ltd.). Further, since the PUVA series has an ultraviolet absorbing effect, it absorbs ultraviolet rays when used in a water-based ink and suppresses the fading of the colorant, so that the light resistance of the writing line can be improved.

Further, as an amino acid having a decoloring action,
There may be mentioned compounds selected from water-soluble amino acids or their salts and their derivatives. The amino acid referred to herein is an organic compound having both a carboxyl group and an amino group in one molecule, and includes those having an imino group instead of the amino group and those having a sulfo group instead of the carboxyl group. In addition, those in which amino groups or imino groups are modified with alkyl groups and those in which hydrogen ions of carboxyl groups or sulfo groups are replaced with metal ions are also included. Also,
The water-soluble amino acid refers to an amino acid that is soluble in water in an amount of 0.5% or more. Neutral amino acids, acidic amino acids, and basic amino acids can be used as the water-soluble amino acids having a decoloring effect. As the neutral amino acid, glycine, glutamine, asparagine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, phenylalanine, tryptophan,
There are tyrosine, carnosine, proline, cystine, phenylglycine, trimethylglycine, and the like, and acidic amino acids include glutamic acid, aspartic acid, ornithine, histidine, lysine, and the like, and one or more of them are mixed and used. be able to. Further, alkyl derivatives of those amino acids, for example, trimethylglycine and betaine-type amphoteric surfactants can be used. As the water-soluble amino acid salt, a cation salt or anion salt of an amino acid can be used. Examples of counter cations include metal cations and ammonium ions, and specifically, sodium glutamate and the like can be used. Examples of the counter anion include a halide anion, a sulfate ion, a nitrate ion, and a phosphate ion, and specifically, arginine hydrochloride can be used. A salt of a basic amino acid and an acidic amino acid can also be used, and specifically, L-arginine L-glutamate or the like can be used. Examples of the water-soluble amino acid salt derivative include amino acid-type amphoteric surfactants. Specifically, Amino Surfact Series (trade name, manufactured by Asahi Kasei Corporation) can be used.

Further, conventionally used conventionally known dyes and / or pigments other than leuco dyes may be used in addition to the above-mentioned color developable compound and developer for the purpose of discoloring the suspension polymer. Good. A suspension polymer also containing these dyes and / or pigments has the above-mentioned usual dyes and / or pigments, in which only the color of the color-forming compound is decolorized by heating or by using a solvent for decolorization. Only the color of will remain and will be discolored. Acid dyes, basic dyes and direct dyes can be used as the dyes. And as a pigment,
Azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based organic pigments, carbon black, synthetic mica, titanium oxide, inorganic pigments such as metal fine powder, and spherical fine particles obtained by suspension polymerization are colored with ordinary dyes. Conventionally known resin pigments described above can be used.

Next, the method for producing the suspension polymer according to the present invention will be described in detail. As a method for producing a suspension polymer to which the present invention is applied, an ordinary suspension polymerization method can be adopted, but the polymerization temperature is preferably 50 to 90 ° C. Further, since the leuco dye according to the present invention is decolored under basic conditions, the pH of the reaction system is adjusted to 4 to 7 by adding an acid such as phosphoric acid before suspension polymerization. When the pH is higher than 7, the leuco dye does not develop color as described above, and when the pH is lower than 4, the dispersion stabilizer described later is dissolved and does not function as a dispersion stabilizer.

In the usual suspension polymerization, a dispersion stabilizer is added to improve the dispersibility of the monomer in the aqueous medium. Also in the present invention, as the dispersion stabilizer, fine particles of an inorganic compound that are insoluble or sparingly soluble in water as used in ordinary suspension polymerization are used, and examples thereof include calcium hydroxide, calcium carbonate, barium hydroxide, and zinc oxide. , Aluminum hydroxide, calcium phosphate, barium phosphate and the like can be used. However, in the present invention, it is necessary to select a dispersion stabilizer that does not dissolve in the above pH range (pH = 4 to 7). Furthermore, in the present invention, since a compound having a phosphoric acid group or a phenolic hydroxyl group is used as a developer for developing a leuco dye, a dispersion stabilizer which reacts with these compounds cannot be used. From the above, in the present invention, as the inorganic compound fine particles that are insoluble or sparingly soluble in water and do not react with the above-mentioned color developer, for example, calcium phosphate, metal phosphate such as barium phosphate is used as a dispersion stabilizer. Is particularly preferable.

Further, as the polymerization initiator used in the present invention, a polymerization initiator such as a peroxide or an azo type or diazo type polymerization initiator which is used in ordinary suspension polymerization can be used. Specifically, for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile), 1,1'-azobis (1-cyclohexane-1-carbonitrile), dimethyl-2,2'-azobisisobutyrate, ammonium persulfate, potassium persulfate, hydrogen peroxide, etc. can be used or required It is also possible to use an inorganic reducing agent such as sodium bisulfite and an organic reducing agent such as alcohol, which are usually used, depending on the case.

The leuco dye and the color developer may be mixed with the monomer before the suspension polymerization, or the suspension polymer may be colored after the suspension polymerization. When mixing before suspension polymerization,
The leuco dye and the color developer can be dispersed in a monomer, and the amount of the leuco dye used is 100% by weight of the suspension polymer 100.
The amount is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to parts by mass.

In addition, conventionally known dyes and / or pigments other than the leuco dye, which are conventionally used, are suspended with the leuco dye and the developer alone or in the same manner as the above-mentioned leuco dye and the developer. It may be mixed with the monomer before the polymerization, or the suspension polymer may be colored after the suspension polymerization. The colored suspension polymer thus obtained is heated or an organic solvent to decolor the portion colored with the leuco dye, and the portion colored with the dye and / or the pigment which does not decolor remains as a result. Will be discolored.

Next, the ink according to the present invention will be described in detail. The ink according to the present invention has a suspension weight obtained by adding an acid to the suspension polymer dispersion obtained by the suspension polymerization method described above to dissolve the dispersion stabilizer, followed by filtration, washing with water and drying. It can be obtained by stirring the combined fine particles in ion-exchanged water. Further, additives such as a surfactant, an antiseptic, an anticorrosive, a drying inhibitor, a lubricant, and a dispersion resin, which are usually used as a raw material for ink, may be added if necessary. However, in view of the object of the present invention, it should not react with the color-developing compound, the color-developing agent, or the suspension polymer, or interfere with color development or decolorization.

Next, the toner according to the present invention will be described in detail. The toner according to the present invention has a suspension weight obtained by adding an acid to the suspension polymer dispersion obtained by the suspension polymerization method described above to dissolve the dispersion stabilizer, and then filtering, washing and drying. It is obtained by an ordinary toner manufacturing method using the coalesced fine particles as a colorant.

Next, the decoloring solvent used for decoloring the colored leuco dye according to the present invention will be described in detail. The decoloring solvent is a compound that dissolves the resin such as the microcapsules containing the suspension polymer and the decoloring agent described above. The solvent for decolorization dissolves the suspension polymer containing the leuco dye and / or the resin containing the decoloring agent when applied on the written line or the printed line, and the starch contained in the paper. Alternatively, the leuco dye is decolorized by directly contacting the decolorizer with the leuco dye. Examples of the organic solvent used in the composition of the decoloring solvent include acetone, methyl ethyl ketone, methyl propyl ketone, ethyl butyl ketone, dibutyl ketone, acetylacetone, acetophenone, 2-pentanone, 3-pentanone, 4-heptanone, 2- Hexanone, 3-methyl-2
-Butanone, 3,3-dimethyl-2-butanone, 2,4
-Dimethyl-3-pentanone, 2,6-dimethyl-4-
Ketone solvents such as heptanone and cyclohexanone, dimethyl ether, diethyl ether, methyl ethyl ether, dipropyl ether, dibutyl ether, 1,2-
Ether solvent such as dimethoxyethane, 1,2-diethoxyethane, pyran, furan, methylfuran, tetrahydrofuran, ethylene oxide, propylene oxide, dioxane, ethyl acetate, butyl acetate, isoamyl acetate, methyl acrylate, ethyl acrylate, Ester-based solvents such as methyl methacrylate and ethyl methacrylate, alcohol-based solvents such as methanol, ethanol, propanol, butanol, pentanol, hexanol, benzyl alcohol, ethylene glycol and propylene glycol, 2-methoxyethanol, 2-ethoxyethanol, Glycol ether solvent such as 1-methoxy-2-propanol, glycol ether ester solvent such as methyl glycol acetate and ethyl glycol acetate, hexa , Hydrocarbon solvents such as heptane, cyclohexane and methylcyclohexane, aromatic hydrocarbon solvents such as benzene, toluene and xylene, methyl chloride, methylene chloride, chloroform, dichloroethane, trichloroethane, tetrachloroethane, perchloroethane, perchloroethylene, A halogenated hydrocarbon solvent such as chlorobenzene, a heterohydrocarbon-containing solvent such as aniline, toluidine, pyridine, bipyridine, dimethylimidazolidinone and dimethyl sulfoxide,
Of these, one kind or a mixture of two or more kinds can be used. Among them, acetone, cyclohexanone, from the viewpoint of decolorizing ability, safety for human body and drying property of solvent,
1,2-dimethoxyethane and 1,2-diethoxyethane are particularly preferable.

A compound containing a nitrogen atom in the molecule, such as a volatile liquid amine or amide, can be added to the erasing solvent as a erasing aid for accelerating the erasing. Since these decoloring aids are basic compounds, they have a function of decoloring the leuco dye that has itself developed color. Examples of the volatile liquid amine added to the composition of this decolorizing solvent include monoethylamine, diethylamine, triethylamine,
Amines such as dipropylamine, butylamine, allylamine, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, propanolamine, aniline, pyridine and bipyridine can be used. As the volatile liquid amide added to the solvent composition for erasing, amides such as formamide and dimethylformamide can be used, and volatile compounds having a nitrogen group in the other molecule such as N-methyl-pyrrolidone. Liquid compounds can also be used. Among these, triethanolamine and N-methyl-2-pyrrolidone are particularly preferable from the viewpoints of decoloring ability, safety for human body and drying property of solvent. These volatile liquid amines or amides can be used alone or as a mixture of two or more kinds, and are added to the decoloring solvent composition in an amount of 0.1 to 10% by mass, preferably 1 to 5%. Mass% is added. The decoloring solvent used for decoloring the colored leuco dye according to the present invention has been described above in detail.

[0022]

EXAMPLES The present invention will now be described in more detail with reference to examples. (Example 1) To 350 g of ion-exchanged water, 5.15 g of sodium phosphate dodecahydrate and 0.9 g of 89% phosphoric acid aqueous solution were added, and after heating to 60 ° C., a TK homomixer (special machinery industry) 12000r using
It was stirred at pm. 20.4 g of a 1.0 M calcium chloride aqueous solution was gradually added dropwise to obtain an aqueous medium containing calcium phosphate (Ca ₃ (PO ₄ ) ₂ ) fine particles (dispersion stabilizer). The pH of this aqueous medium was 4.6. Next, 20 g of styrene (monomer), Pink 535 (Leuco dye manufactured by Yamada Chemical Co., Ltd., trade name) 0.12 g,
Propyl gallate (developer) 0.2 g, ethanol 1.
0 g of the mixture, which had been mixed by stirring in advance, was added to the above aqueous medium, heated to 60 ° C., and uniformly dispersed at 12000 rpm using a TK homomixer under a nitrogen atmosphere. To this, 0.5 g of 2,2′-azobisisobutyronitrile (polymerization initiator) was added, and stirring was maintained for 20 minutes. Then, after the temperature was raised to 80 ° C., the mixture was stirred for 6 hours.
After completion of the reaction, hydrochloric acid was added to dissolve calcium phosphate, filtered, washed with water, and dried to obtain a pink suspension polymer. The average particle size of the obtained suspension polymer was 8.5 μm. 2 g of the obtained suspension polymer, 25.9 g of ion-exchanged water, 2 g of trimethylglucine, and 0.1 g of xanthan gum were mixed with stirring to obtain an aqueous pink ink. The obtained aqueous pink ink was filled in an ink tank in the same manner as a commercially available direct liquid marker (Popstar Extra Fine, Zebra Co., Ltd., trade name), and then mounted with a valve-equipped tip cover, A polyester pen tip and a cap were fitted to create an aqueous pink marker. Using the created marker, it was handwritten on a dry PPC paper (trade name, manufactured by Oji Paper Co., Ltd.).

(Example 2) To 350 g of deionized water, 5.15 g of sodium phosphate dodecahydrate and 0.5 g of 89% phosphoric acid aqueous solution were added, and the mixture was heated to 60 ° C.
It stirred at 12000 rpm using the type | formula homo mixer. To this, 30.3 g of 1.0 M barium chloride aqueous solution
Was gradually added dropwise to obtain an aqueous medium containing fine particles of barium phosphate (Ba ₃ (PO ₄ ) ₂ ) (dispersion stabilizer). The pH of this aqueous medium was 6.6. Next, styrene 20g, H
-2114 (manufactured by Yamada Chemical Co., Ltd., leuco dye, trade name) 0.12 g, 89% phosphoric acid aqueous solution 0.3 g, and ethanol 1.0 g were mixed with stirring in advance, and the mixture was added to the above aqueous medium. Then, the mixture was heated to 60 ° C. and uniformly dispersed at 12000 rpm using a TK type homomixer in a nitrogen atmosphere. To this, 0.5 g of 2,2′-azobisisobutyronitrile (polymerization initiator) was added, and stirring was maintained for 20 minutes. Then, after the temperature was raised to 80 ° C., the mixture was stirred for 6 hours. After completion of the reaction, hydrochloric acid was added to dissolve barium phosphate, and the suspension was filtered, washed with water and dried to obtain a pink suspension polymer.
The average particle size of the obtained suspension polymer was 8.0 μm. 2 g of the obtained suspension polymer, 25.75 ion-exchanged water
g, PVP K-15 2g, xanthan gum 0.25
g was mixed by stirring to obtain a green ink for gel ink ballpoint pen. The obtained green ink for gel ink ballpoint pens is commercially available gel ink ballpoint pens (BW
-100, manufactured by Zebra Co., Ltd., trade name, stainless ball diameter 0.8 mm), the polypropylene refill is filled with the same method, then the pen tip is fitted, and an appropriate amount of ink follower is injected from the tail portion and centrifuged. 1960 m ・ s depending on machine
^-2 (200 G) was degassed to prepare a gel ink ballpoint pen. It was handwritten on the dry PPC paper using the created gel ink ballpoint pen.

(Example 3) After adding 5.15 g of sodium phosphate dodecahydrate to 350 g of ion-exchanged water, T
The mixture was stirred at 12000 rpm using a K type homomixer. Add 1.0M calcium chloride aqueous solution to 20.4
g was gradually added dropwise to obtain an aqueous medium containing calcium phosphate fine particles. 20 g of p-aminostyrene (monomer)
Was added to the above aqueous medium and heated to 60 ° C., and then, under nitrogen atmosphere, using a TK homomixer at 12000 rp
and evenly dispersed. To this, 0.5 g of 2,2′-azobisisobutyronitrile (polymerization initiator) was added, and 20
Stirring was maintained for a minute. Then, it heated up at 80 degreeC and stirred for 6 hours. After completion of the reaction, hydrochloric acid was added to dissolve calcium phosphate, filtered, washed with water and dried to obtain a milky white suspension polymer. The average particle size of the obtained suspension polymer was 8.5 μm. 4 g of this milky white fine powder and a specific surface area of 200 m ²
0.05 g of hydrophobic silica / g (BET method) was externally added to 6 g of the pink fine powder obtained in Example 1 to obtain a dry toner. 90g of this carrier and ferrite carrier are mixed,
A non-magnetic two-component developer was used. This developer was used to print on dry PPC paper with a laser printer (FS-600, manufactured by Kyocera Corporation).

(Comparative Example 1) PSD-184 (manufactured by Nippon Soda Co., Ltd., leuco dye, trade name) 5 g, 3,5-dihydroacetophenone 3 g, GPPS-673 (manufactured by A & M Styrene Co., polystyrene, trade name) ) 2
0 g was heated and mixed using a heating kneader to obtain a colored lump-shaped pigment. The pigment was pulverized with a jet mill to obtain a black fine powder pigment having a particle size of 5 to 10 μm, which was classified by classification. 15 g of this fine powder pigment, PVP K-15
8 g, Deltop (Takeda Pharmaceutical Co., Ltd., preservative, trade name) 0.3 g, Emulgen 707 (Kao Co., non-ionic surfactant, trade name) 0.8 g, xanthan gum 0.6 g, ion exchange 75.3 g of water is stirred and mixed using a stirrer, and the viscosity is 131 mPa · s (25 ° C., 150 s
^-1 ) Gel ink for ballpoint pens was obtained. A gel ink ballpoint pen was created using this ink in the same manner as in Example 2, and handwriting was performed on a dry PPC paper using this.

(Comparative Example 2) To 350 g of ion-exchanged water, 5.15 g of sodium phosphate dodecahydrate was added, and after heating to 60 ° C., 12,000 r was obtained using a TK homomixer.
Stir-mixed at pm. 20.4 g of 1.0 M calcium chloride aqueous solution was gradually added dropwise to this to obtain an aqueous medium containing calcium phosphate fine particles. PH of this aqueous medium
Was 10.9. Using this aqueous medium, Example 1
An attempt was made to obtain a suspension polymer in the same manner as, but the leuco dye was decolored, and a colored suspension polymer was not obtained.

(Comparative Example 3) To 350 g of ion-exchanged water, 5.15 g of sodium phosphate dodecahydrate and 3.5 g of 89% phosphoric acid were added, and after heating to 60 ° C., a TK homomixer was used. The mixture was stirred and mixed at 12000 rpm. 20.4 g of a 1.0 M calcium chloride aqueous solution was gradually added dropwise to this to obtain an aqueous medium containing fine particles of calcium phosphate, but the pH was low at 2.9, and thus calcium phosphate was metathesized. Since calcium phosphate, which is a dispersion stabilizer, was dissolved, suspension polymerization could not be performed.

(Dispersion Stability Test) The inks and toners obtained in the above Examples 1 to 3 and Comparative Example 1 were measured for particle size by laser diffraction particle size analyzer SALD-2.
It measured using 100 (made by Shimadzu Corporation).
Then, after allowing the ink and toner to stand for about half a year,
The particle size was measured again. The particle size before and after standing was compared, and the dispersion stability was evaluated using this.

(Decoloring Test Using Decoloring Solvent) The lines drawn with the inks obtained in Examples 1 and 2 and Comparative Example 1 and the line printed with the toner obtained in Example 3 are as follows: A few drops of acetone were directly dropped as a decoloring solvent, and the color of those lines after drying was visually confirmed. (Decoloring test by heating) With respect to the drawn lines, an iron heated to about 200 ° C was directly pressed, and the colors of the drawn lines were visually confirmed.

The results of each test are summarized in Table 1.

[Table 1] 1) Evaluation of dispersion stability ○: No change in particle size ×: Increase in particle size 2) Evaluation of decolorization by a solvent for decolorization ○: Change to colorless ×: No change to colorless 3) Decolorization by heating Change: ○ Change to colorless ×: Not change to colorless

As is apparent from Table 1, the lines drawn with the ink and toner prepared in Examples 1 to 3 according to the present invention were all erased well. In addition, the ink and toner had high dispersion stability, and the particle size of the suspension polymer, which was fine particles, did not change for about half a year. On the other hand, in Comparative Example 1, although the decoloring property was good, the dispersion stability was poor, and the particles were aggregated after standing for about half a year, resulting in an increase in the particle size.

[0032]

As described above, since the suspension polymer according to the present invention contains a leuco dye, an ink or the like using this can be decolored by heating. Further, since the leuco dye is coated with the resin of the suspension polymer, even if the decoloring agent is coexisted in the ink containing the suspension polymer of the present invention, the leuco dye does not come into direct contact with the leuco dye so that the color is erased. There is no such thing. Then, by dissolving the suspension polymer not only by heating but also by using an organic solvent, the decoloring agent preferentially binds to the color developing agent, thereby enabling decoloring. Furthermore, the leuco dye has high light resistance because it is not directly exposed to sunlight due to the coating of the suspension polymer resin. Further, since the fine particles containing the leuco dye are produced by suspension polymerization, not by the pulverization method, the particle diameter and particle shape are relatively uniform, and the particle shape is spherical. This brings about an effect that when the fine particles are used in a liquid ink, the dispersibility is improved and therefore the fine particles do not precipitate even if the viscosity of the ink is not paid so much attention. In addition, since the particle size is reduced, the particle strongly penetrates the writing surface, and the water resistance of the writing line is improved, and the writing feeling is also improved. Further, when the fine particles are used for a toner, a particle having a relatively small particle size and a spherical particle shape is obtained, and the toner adheres strongly and uniformly to the latent image, so that a high quality image is obtained. Obtainable. Due to the above effects, it is expected that the utilization range of the leuco dye, which has been relatively difficult to handle so far, is expanded.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 9/087 G03G 9/08 361 9/09 384 F term (reference) 2H005 AA21 AB06 CA21 4J002 BC031 BC101 BC111 BG071 DH027 EE037 EJ037 EJ047 EJ067 EW047 FD096 FD207 HA06 4J011 JA04 JB26 4J039 AD03 AD10 BE01 BE02 CA06

Claims (7)

[Claims] 1. A suspension polymer which is colored by containing at least a leuco dye and a color developer. 2. A polymerization start after adding a mixture containing at least a vinyl monomer, a leuco dye and a color developer to an aqueous medium containing a dispersion stabilizer and having a pH of 4 to 7 and uniformly stirring and dispersing the mixture. A suspension polymer obtained by adding an agent and carrying out suspension polymerization. 3. The dispersion stabilizer is calcium phosphate or barium phosphate.
The suspension polymer described in 1. 4. An ink containing the suspension polymer according to any one of claims 1 to 3. 5. The ink according to claim 4, which contains a decolorizing agent composed of a basic compound containing a nitrogen atom and can be easily decolorized or discolored by an organic solvent or heating. 6. A toner containing the suspension polymer according to claim 1. 7. The toner according to claim 6, wherein the toner contains a decolorizing agent composed of a basic compound containing a nitrogen atom and can be easily decolorized or discolored by an organic solvent or heating.