JPH11140343A - Colorant composition, ink jet recording ink, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a colorant composition which does not cause nozzle plugging, has excellent weathering resistance, water resistance, solvent resistance, etc., and is suited for an ink for ink jet recording by using colored particles prepared by encapsulating a pigment with a resin obtained by polymerizing a polymer having a radical-polymerizable group and emulsifiability in water. SOLUTION: The content of the hydrophilic groups of the emulsifiable polymer is desirably 8.0×10<3> to 1.4×10<2> mol./g. By encapsulating a pigment with a resin obtained by polymerizing a polymer having radical-polymerizable group and emulsifiability in water with a radical-polymerizable monomer and/or a crosslinking agent, the hydrophilicity of the emulsifiable polymer can be further reduced to form water-resistant resin particles. Therefore, the separation of the resin form the surface of the pigment can hardly occur, and the nozzle plugging can hardly occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a colorant composition which can be used for printing inks such as inks for ink jet recording, paints, resist materials, liquid crystal color filters, etc., and ink jet recording using the colorant composition. The present invention relates to an ink for use and a method for producing the same.

[0002]

2. Description of the Related Art As an ink jet recording ink, an aqueous ink composition containing a dye as a colorant and an aqueous medium is currently in practical use. However, in such an aqueous ink composition, since a dye is used as a colorant,
There has been a problem that the weather resistance is poor and the water resistance is poor, so that bleeding easily occurs.

As a method for solving the problem caused by using a dye as a colorant, a method in which a paste in which a pigment as a colorant is dispersed is used as an ink for inkjet recording has been proposed (JP-A-6-16684).
No. 0, Japanese Unexamined Patent Publication No. Hei 8-113538, International Publication W
O95 / 16002, etc.).

[0004] However, the ink composition in which these pigments are dispersed has a problem that the pigments are not sufficiently hydrophilized and thus easily adhere to the inside of the nozzle, and the nozzle is easily clogged. Further, since a water-soluble pigment dispersant and other resin components are used, there is a problem that the viscosity of the ink composition is high.

Japanese Patent Application Laid-Open No. 9-151342 proposes a technique in which a pigment is used as a colorant and the pigment is microencapsulated with an anionic organic polymer compound. Is high, the resin is easily detached from the pigment surface, and the pigment is exposed,
There is a problem that the nozzle is easily clogged.

[0006] An object of the present invention is to solve these conventional problems, to prevent clogging of the nozzle, and to improve the weather resistance,
An object of the present invention is to provide a colorant composition excellent in water resistance, dissolution resistance and the like, which is suitable as an ink for ink jet recording, an ink for ink jet recording using the colorant composition, and a method for producing the same.

[0007]

The colorant composition according to the first aspect of the present invention is a pigment composition comprising a resin obtained by polymerizing a polymer having a radical polymerizable group and having an emulsifying property in water. Is characterized by containing colorant particles in which is encapsulated.

[0008] The ink for ink jet recording according to the first aspect of the present invention is an ink for ink jet recording containing the colorant composition according to the first aspect of the present invention.

The colorant composition according to the second aspect of the present invention is obtained by polymerizing a mixture of a polymer having a radically polymerizable group and having an emulsifying property in water and a radically polymerizable monomer. It is characterized by containing colorant particles in which a pigment is encapsulated by a resin.

An ink jet recording ink according to a second aspect of the present invention is an ink jet recording ink containing the colorant composition according to the second aspect of the present invention.

[0011] In the first and second aspects, the polymer having emulsifiability in water (hereinafter referred to as “emulsifiable polymer”) is a polymer which becomes emulsified when added to water and stirred and mixed. Say. Specifically, at room temperature, a 100% toluene solution of a polymer having a solid content of 60% by weight is used.
g is added to 300 g of ion-exchanged water, and it is determined whether or not an emulsified state is obtained by stirring and mixing. As the emulsifying polymer, a polymer in which the average particle size of the emulsion in the emulsified state is 20 μm or less is preferable.

The emulsifiable polymer is generally given emulsifiability by containing a hydrophilic group. The hydrophilic group content of the emulsifying polymer is from 8.0 × 10 ^{−3 to} 1.4 × 10 ^3.
-2 mol / g is preferable, and 9.5 × 1 is more preferable.
0 ^{-3 to} 1.3 × 10 ^-2 mol / g. Here, the hydrophilic group includes an acid group (such as a carboxylic acid group, a sulfonic acid group, or a phosphoric acid group), a basic group (such as a quaternary ammonium base), and a water-soluble nonionic group (such as a polyethylene glycol chain).
It is. Among these hydrophilic groups, having a self-emulsifying ability, a small number of miscellaneous ions, and a steric stabilizing effect, the number of repeating units of polyethyleneoxy (hereinafter, referred to as
Polyethylene glycol chains having a “degree of polymerization” of 8 or more are most preferred. Such a polyethylene glycol chain is preferably at least 50% by mole, more preferably at least 75%, of the hydrophilic groups. The calculation of the number of moles of the polyethylene glycol chain is based on one repeating unit being 1 mole. Therefore, for example, in the case of a polyethylene glycol chain having a degree of polymerization of 15, the calculation is made as 15 mol.

The radical polymerizable group of the emulsifiable polymer in the first and second aspects is not particularly limited as long as it is an unsaturated bond group capable of undergoing radical polymerization. Examples thereof include an acryloyl group and a methacrylic group. And a royl group and an aromatic substituted vinyl group. The content of these radically polymerizable groups is from 5.0 × 10 ⁻⁵ to 1.
0 × 10 ⁻³ mol / g is preferred. When the content of the radical polymerizable group is small, the graft reaction between the polymers by polymerization becomes insufficient, and when the content is too large, gelation is excessively promoted. In addition to a decrease in strength, the resin covering the pigment may be peeled off due to an excessively high cohesive force.

The number average molecular weight of the emulsifying polymer in the first aspect and the second aspect is from 1,000 to 500,000.
And more preferably 1500 to 1
50,000. If the molecular weight is too low, the hydrophilicity of the emulsifiable polymer becomes too high, and the resin is easily detached from the pigment surface. On the other hand, if the molecular weight is too high, the viscosity of the resin may be too high and handling may be difficult.

[0015] In the first and second aspects, the glass transition point of the emulsifiable polymer is preferably from -50 to 70 ° C. If the glass transition point is lower than this range, the image fixing strength may decrease when used as an ink for inkjet recording. On the other hand, when the glass transition point is higher than this range, when used as an ink for ink jet recording, the adhesion to a transfer member such as paper may be deteriorated, and the image fixing strength may be reduced.

In the first aspect, the pigment is encapsulated with a resin obtained by polymerizing an emulsifiable polymer having a radical polymerizable group. Preferably, the pigment is contained in an emulsifiable polymer having a radical polymerizable group, and this is dispersed in water to polymerize the emulsifiable polymer in an emulsion state to encapsulate the pigment. Since the emulsifiable polymer has an appropriate hydrophilicity, it forms an emulsion of fine particles with the pigment contained therein. Preferably, an emulsion having an average particle size of 1 μm or less is formed. In this state, the pigment can be encapsulated by polymerizing the emulsifying polymer. When the emulsifiable polymer is polymerized, the molecular weight increases, so that the hydrophilicity decreases and the resin is less likely to be detached from the pigment surface. Therefore, when used as an inkjet recording ink,
Clogging of the nozzle and the like are less likely to occur. Further, since the resin covering the pigment has decreased hydrophilicity due to polymerization, the water resistance is improved, and an ink jet recording ink having excellent water resistance can be obtained. Further, by increasing the molecular weight, the function as a binder resin is enhanced, and the image fixing strength is excellent.

In the second aspect, the pigment is encapsulated by a resin obtained by polymerizing a mixture of an emulsifiable polymer having a radical polymerizable group and a radical polymerizable monomer. Similarly to the first aspect, an emulsion is formed in a state where a pigment is contained in a mixture of the emulsifying polymer and the radical polymerizable monomer, and the emulsifying polymer and the radical polymerizable monomer are polymerized in this emulsion state. Since the mixture contains an emulsifying polymer, it can be dispersed as an emulsion of fine particles. Preferably, the emulsion has an average particle diameter of 1 μm or less. In this state, the emulsifiable polymer and the radical polymerizable monomer inside the emulsion are polymerized, so that fine colorant particles containing a pigment can be obtained. Also, the second
In the aspect described above, since the radical polymerizable monomer is added for polymerization, the hydrophilicity of the emulsifiable polymer is further reduced, and water-resistant resin particles can be obtained. Therefore, detachment of the resin from the pigment surface is less likely to occur. Therefore, when used as an ink for inkjet recording, clogging of the nozzle is less likely to occur.

The radical polymerizable monomer used in the second aspect may be any monomer having an unsaturated bond group capable of undergoing radical polymerization, for example, an acryloyl group,
Monomers having a methacryloyl group, an aromatic-substituted vinyl group and the like can be mentioned. The molecular weight of the radical polymerizable monomer is preferably 200 or more, and more preferably 250 or more. If the molecular weight is too low, when the emulsion becomes emulsified together with the emulsifying polymer, it may migrate to the aqueous phase and generate particles containing no pigment.
What is necessary is just to have at least one radical polymerizable group,
It may be a polyfunctional monomer having a plurality of radically polymerizable groups.

Specific examples of the radical polymerizable monomer include cetyl methacrylate, stearyl methacrylate, triethylene glycol dimethacrylate, 1,6
Monofunctional or polyfunctional vinyl compounds such as hexanediol dimethacrylate, 2,2'-bis [4- (methacryloxydiethoxy) phenyl] propane, trimethylolpropane triacrylate, and pentaerythritol triacrylate, phenylglycidyl ether / isophorone diisocyanate A urethane acrylate,
Urethane acrylate composed of glycerin dimethacrylate / hexamethylene diisocyanate, and the like.

The colorant composition according to the third aspect of the present invention comprises a polymer having a reactive group for addition polymerization and a water-emulsifying polymer, and a crosslinking agent for addition-polymerizing the polymer. It is characterized by containing colorant particles in which a pigment is encapsulated by a resin obtained by the reaction.

[0021] The ink jet recording ink according to the third aspect of the present invention is an ink jet recording ink containing the colorant composition according to the third aspect of the present invention.

The colorant composition according to the fourth aspect of the present invention comprises a polymer having a reactive group for addition polymerization and emulsifiable in water, and a compound having a reactive group for addition polymerization (hereinafter referred to as a compound having a reactive group for addition polymerization). , A "addition-reactive compound"), and a colorant particle obtained by encapsulating a pigment with a resin obtained by reacting the polymer and a cross-linking agent for addition-polymerizing the compound. I have.

An ink jet recording ink according to a fourth aspect of the present invention is an ink jet recording ink containing the colorant composition according to the fourth aspect of the present invention.

The emulsifiable polymer according to the first and second aspects, except that the emulsifiable polymer according to the third and fourth aspects has a reactive group for addition polymerization instead of the radical polymerizable group. It is the same as the polymer, and is a polymer that becomes an emulsified state when added to water and stirred and mixed. Therefore, it preferably has the same hydrophilic group as the emulsifiable polymer of the first aspect and the second aspect. Further, the number average molecular weight is 1 as in the first and second aspects.
It is preferably from 000 to 500,000, more preferably from 1500 to 150,000. Further, the glass transition point is preferably from -50 to 70C.
Examples of the type of the polymer include polyester, polyurethane, and polyurea.

The reactive group for addition polymerization of the emulsifiable polymer according to the third and fourth aspects includes a hydroxyl group, an epoxy group and an isocyanate group. The content of these reactive groups is from 5.0 × 10 ^{−5 to} 1.0 ×
It is preferably 10 ⁻³ mol / g. When the content of the reactive group is low, the graft reaction between the polymers becomes insufficient, and conversely, when the amount of the reactive group is too large, gelation is excessively promoted, and when used as an inkjet recording ink,
As the image fixing strength decreases, the cohesive force becomes too high and the resin may be detached from the pigment.

As the crosslinking agent used in the third and fourth aspects, a compound having a functional group which reacts with the reactive group of the emulsifiable polymer is used. When the reactive group of the emulsifying polymer is an isocyanate group or an epoxy group, an amine compound having an amino group such as a diamine or a polyamine, or a hydroxyl group-containing compound such as a diol or a polyol is used. When the reactive group of the emulsifying polymer is a hydroxyl group, a compound such as diisocyanate or polyisocyanate is used as a crosslinking agent.

In the third aspect, preferably, the emulsifiable polymer containing the pigment is dispersed in water to form an emulsion, and a cross-linking agent is added to the emulsion, and the inside of the emulsion is subjected to addition polymerization to encapsulate the pigment. Colorant particles. The emulsifiable polymer containing the pigment therein becomes an emulsion of fine particles, and preferably an emulsion having an average particle diameter of 1 μm or less. By performing addition polymerization in such a state, fine resin particles can be obtained. Further, by addition polymerization of the emulsifying polymer, hydrophilicity is reduced and water resistance is improved. Therefore, the resin obtained by addition polymerization has high water resistance and is hardly detached from the pigment surface. Therefore, when used as an ink for inkjet recording, nozzle clogging and the like are less likely to occur. When a water-soluble crosslinking agent is used as the crosslinking agent, the emulsifiable polymer can be polymerized by interfacial polymerization.

In the fourth aspect, a mixture of the emulsifiable polymer and the addition-reactive compound is reacted with a crosslinking agent to polymerize the mixture. By using a compound having lower hydrophilicity than the emulsifying polymer as the addition-reactive compound, the resin obtained by addition polymerization becomes further lower in hydrophilicity, and the water resistance of the resin can be further increased. Accordingly, the resin is less likely to be detached from the pigment surface, and when used as an ink for inkjet recording, clogging of the nozzle can be further less likely to occur.

In the fourth aspect, examples of the addition-reactive compound to be mixed with the emulsifying polymer include, for example, isophorone diisocyanate, tetramethylxylylene diisocyanate, and an oligomer composed of them and trimethylolpropane.

In the colorant particles according to the first to fourth aspects of the present invention, the ratio of pigment to resin is (pigment) /
(Resin), preferably 5/95 to 60/40, more preferably 10/90 to 50/50. If the amount of the pigment is too small, the image density may be too low when used as an inkjet recording ink. On the other hand, if the pigment concentration is too high, the coating of the pigment with the resin becomes insufficient, and when used as an inkjet recording ink, nozzle clogging and the like may occur.

In the second aspect of the present invention, the weight ratio of the emulsifiable polymer to the radical polymerizable monomer is (emulsifiable polymer) / (radical polymerizable monomer) 95/5 to 1
0/90 is preferable, and 90/10 to 4 is more preferable.
0/60.

In the fourth aspect of the present invention, the weight ratio of the emulsifying polymer to the addition-reactive compound is (emulsifying polymer) / (addition-reactive compound), and is from 95/5 to 10/90.
And more preferably 90/10 to 40/60.
It is.

The solid concentration in the ink jet recording ink according to the first to fourth aspects of the present invention is 2 to 60.
% By weight, more preferably 10 to 10% by weight.
40% by weight. If the solid content is low, an ink film having a sufficient thickness cannot be formed, and the image density may be insufficient. On the other hand, if the solid content concentration is too high, the viscosity becomes high, and the ejection from the head of the inkjet printer may become unstable.

The pigment concentration in the ink for ink jet recording is preferably at least 4% by weight, more preferably at least 8% by weight. In the ink jet recording ink according to the first to fourth aspects of the present invention, a drying inhibitor such as diethylene glycol or triethylene glycol may be used to prevent the ink from drying. The amount of the anti-drying agent used is 100
It is preferably at most 40 parts by weight, more preferably at most 10 parts by weight, based on parts by weight. If the amount of the drying inhibitor is too large, the viscosity of the ink may exceed a desired range, and it may take time to dry the ink on paper or the like.

Further, the viscosity of the ink jet recording ink according to the present invention is preferably 20 cps or less, more preferably 10 cps or less. In addition, by using a polyfunctional monomer as the radical polymerizable monomer in the second aspect of the present invention to form a crosslinked structure, heat resistance, solvent resistance, water resistance, and the like can be further improved. Similarly, in the fourth aspect of the present invention, heat resistance, solvent resistance, and water resistance can be further enhanced by using a polyfunctional compound as the reactive compound to form a resin having a crosslinked structure.

Hereinafter, a method for producing the colorant composition and the ink for inkjet recording of the present invention will be described.
When the water-soluble polymerization initiator is used, the colorant composition and the ink for inkjet recording according to the first and second aspects of the present invention can be manufactured by the following manufacturing method using an emulsion polymerization method.

That is, in the production method according to the fifth aspect of the present invention, a step of mixing a polymer having radical polymerizability and emulsifiability in water with a pigment to obtain a mixture in which the pigment is uniformly dispersed. And dispersing the mixture in water to form an emulsion, and after adding a water-soluble polymerization initiator to the emulsion, heating and polymerizing the inside of the emulsion to encapsulate the emulsion. .

As the water-soluble polymerization initiator, those generally used as a water-soluble radical polymerization initiator can be used, and for example, potassium persulfate can be used.

The mixture of the emulsifying polymer and the pigment may contain a solvent for the emulsifying polymer, if necessary. When the colorant composition and the ink for inkjet recording according to the second aspect of the present invention are produced, the above mixture can be obtained by mixing an emulsifiable polymer, a pigment and a radical polymerizable monomer. The solvent added to the mixture may be removed before the start of the polymerization, or may be removed after the polymerization. When mixing the radical polymerizable monomer, the solvent contained in the mixture may be replaced with the radical polymerizable monomer.

When an oil-soluble polymerization initiator is used as the polymerization initiator, it can be produced by the following production method using a microsuspension polymerization method. That is, in the production method according to the sixth aspect of the present invention, the pigment is uniformly dispersed by mixing a polymer having a radical polymerizable group and having emulsifiability in water, a pigment, and an oil-soluble polymerization initiator. It is characterized by comprising a step of obtaining a mixture, a step of dispersing the mixture in water to form an emulsion, and a step of heating the emulsion to polymerize the inside of the emulsion and encapsulate the emulsion.

As the oil-soluble polymerization initiator, those generally used as an oil-soluble radical polymerization initiator can be used. For example, lauroyl peroxide and azobisisobutyronitrile can be used.

When the mixture of the emulsifying polymer, the pigment and the oil-soluble polymerization initiator is mixed, a solvent for the emulsifying polymer and the oil-soluble polymerization initiator may be mixed if necessary. When producing the colorant composition and the ink for inkjet recording according to the second aspect of the present invention, a radical polymerizable monomer can be further mixed. The solvent contained in the mixture may be removed before the start of the polymerization, or may be removed after the polymerization. When mixing the radical polymerizable monomer, the emulsifying polymer and the solvent are first mixed, and then, before mixing with the pigment, the radical polymerizable monomer is added and the solvent is removed. The monomer may be replaced.

The colorant composition and the ink for ink-jet recording according to the third and fourth aspects of the present invention can be produced by the following production method using an interfacial polymerization method. That is, the production method according to the seventh aspect of the present invention comprises:
A step of mixing a polymer having a reactive group for addition polymerization and having emulsifiability in water with a pigment to obtain a mixture in which the pigment is uniformly dispersed, and a step of dispersing the mixture in water to form an emulsion And a step of adding a crosslinking agent to the emulsion and subjecting the inside of the emulsion to addition polymerization to encapsulate the emulsion.

A solvent may be added to the mixture of the emulsifying polymer and the pigment, if necessary. In this case, it is preferable to first add a solvent to the emulsifiable polymer, dilute the polymer, and then mix it with the pigment. The solvent in the mixture may be removed before starting the polymerization or after the polymerization. Fourth Embodiment of the Present Invention
When the colorant composition and the ink for inkjet recording according to the above aspect are produced, an addition reactive compound may be mixed in the above mixture. When mixing the addition reactive compound, the solvent in the emulsifiable polymer and the addition reactive compound may be replaced before mixing the pigment.

In the production method according to the fifth, sixth, and seventh aspects of the present invention, an emulsifier may be used when preparing an emulsion by emulsification. It is preferable to add these emulsifiers to the mixture in advance. The content of the emulsifier is preferably 10 parts by weight or less, more preferably 1 part by weight or less, based on 100 parts by weight of the solid content of the mixture. If the amount of the emulsifier is too large, the resin may peel off from the pigment due to its emulsifying power.

Further, in the production method of the present invention,
It is preferable to prepare an emulsion having an average particle size of 1 μm or less. By reducing the average particle size of the emulsion, the average particle size of the obtained colorant particles can be reduced, and for example, when used as an inkjet recording ink, an image with high saturation can be obtained.

The average particle diameter of the colorant particles in the present invention is preferably 1 μm or less, more preferably 0.6 μm or less. By reducing the particle size of the colorant particles, storage stability when used as an inkjet recording ink can be increased,
Also, noise clogging can be prevented.

[0048]

BEST MODE FOR CARRYING OUT THE INVENTION Preparation Example 1: Synthesis of emulsifiable polymer A
As described below, emulsifiable polymer A having a methacryloyl group in the molecular chain was synthesized.

360.0 g of toluene was charged into a 2-liter separable flask equipped with a temperature controller, a nitrogen inlet, a squirrel-type stirring blade, and a reflux tube, and the temperature was raised to 90 ° C. To this, 120.0 g of toluene, 210.0 g of a styrene monomer, 90.0 g of methacrylic acid, and polyethylene glycol macromer (trade name “RMA150M”, manufactured by Nippon Emulsifier Co., Ltd.) represented by the following formula (1) 3
A mixture of 00.0 g and 18.0 g of t-butylperoxy-2-ethylhexanate (trade name “Kayaester-O”, manufactured by Nippon Kayaku Co., Ltd.) was added dropwise over 2 hours. After continuing the radical polymerization for another 2 hours, toluene 60.0
g, t-butylperoxy-2-ethylhexanate (trade name: Kayaester-O) 1.80 g was added dropwise over 30 minutes, and the reaction was continued for 1 hour after completion of the addition. Thereafter, the temperature was raised to 130 ° C. while removing toluene, 118.9 g of glycidyl methacrylate, 0.059 g of methoxyhydroquinone, and 0.59 g of tetra-n-butylammonium bromide were added, and the reaction was continued for 2 hours. When the acid value became 0, the reaction was terminated. After the reaction was completed, a small amount of toluene was added to adjust the solid content to 80% by weight. The calculated value of the content of the hydrophilic group contained in the obtained polymer is 1.14 × 10 ⁻² mol / g.

[0050]

Embedded image

Preparation Example 2: Synthesis of emulsifiable polymer B Emulsifiable polymer B having an isocyanate group at a terminal was synthesized as follows.

In the same separable flask as above, polyethylene glycol having an OH group at one end and having a polymerization degree of 15 (trade name “MPG-081”, manufactured by Nippon Emulsifier Co., Ltd.)
692.0 g, 808.0 g of an aromatic glycol ether represented by the following chemical formula (trade name "BA-4U", manufactured by Nippon Emulsifier Co., Ltd.), 375 g of toluene, and 0.12 g of dibutyltin laurate. The charge and the temperature were raised to 140 ° C. to remove water contained in the mixture. Thereafter, the temperature was lowered to 100 ° C., and a mixed solution of 666.0 g of isophorone diisocyanate (manufactured by Huls) and 166.0 g of toluene was added. After removing the toluene, the temperature was gradually raised to 160 ° C., and the reaction was performed for 2 hours. After confirming that the relative intensity of the peak of the isocyanate group in the infrared absorption spectrum became constant, the reaction was completed. Toluene was added to the reaction solution to adjust the solid content to 80% by weight. The calculated value of the content of the hydrophilic group contained in the obtained polymer is 1.06 × 10 ⁻² mol / g.

[0053]

Embedded image

In the chemical formula 2, Ph represents a benzene ring.

[0055] For each of the emulsifiable presence emulsion polymers A and emulsifying polymer B, it was evaluated for the presence or absence of emulsifiable in water. 80 above
Toluene was added to a 60% by weight toluene solution of a polymer solution of 100% by weight to prepare a 60% by weight toluene solution. 100 g of this toluene solution was added to 300 g of ion-exchanged water, mixed with stirring, and observed for an emulsified state. . As a result, it was confirmed that both emulsifiable polymer A and emulsifiable polymer B were emulsified. When the average particle size of the emulsion was measured by a light scattering method, the average particle size of the emulsifying polymer A was 0.11 μm, and the average particle size of the emulsifying polymer B was 0.092 μm.

Example 1 (Formation of Colorant Particles According to the First Aspect of the Invention by Emulsion Polymerization Method) 56.25 parts by weight of emulsifying polymer A, 15.0 parts by weight of a pigment (Pig. Yellow 14), and toluene 28 .75 parts by weight using a sand grinder to obtain a pigment dispersion paste. 100 parts by weight of the pigment-dispersed paste, 240 parts by weight of ion-exchanged water, and sodium dioctylsulfosuccinate 1.2 as an emulsifier
A part by weight of the mixed aqueous solution was mixed with stirring to prepare an emulsion having an average particle diameter of 0.36 μm. Next, after removing toluene from this emulsion, it was transferred to a 1-liter reaction vessel and the temperature was adjusted to about 75 ° C. 24 parts by weight of a 1.0% by weight aqueous solution of potassium persulfate was added dropwise thereto,
The emulsion polymerization was continued for 5 hours. No formation of aggregates was observed, and colorant particles having an average particle diameter of 0.36 μm were obtained.
When the obtained colorant particles were observed with a transmission electron microscope, no detachment of the pigment was observed, and the pigment was encapsulated in the resin.

Example 2 (Formation of Colorant Particles According to Second Embodiment of the Present Invention by Emulsion Polymerization Method) 43.75 parts by weight of emulsifying polymer A, 15.0 parts by weight of pigment (carbon black), radical polymerizable Using a sand grinder, 10.0 parts by weight of triethylene glycol dimethacrylate as a monomer and 31.25 parts by weight of toluene were mixed to obtain a pigment-dispersed paste. 100 parts by weight of this pigment dispersion paste, 240 parts by weight of ion-exchanged water, and a mixed aqueous solution of 1.2 parts by weight of sodium dioctylsulfosuccinate as an emulsifier were mixed with stirring to prepare an emulsion having an average particle diameter of 0.34 μm. . Next, after removing toluene from this emulsion, it was transferred to a 1-liter reaction vessel and the temperature was adjusted to about 75 ° C. 24 parts by weight of a 1.0% by weight aqueous solution of potassium persulfate was added dropwise thereto, and emulsion polymerization was continued for 5 hours. No formation of aggregates was observed, and the average particle diameter was 0.36 μm.
m colorant particles were obtained. When the obtained colorant particles were observed with a transmission electron microscope, no detachment of the pigment was observed, and the pigment was encapsulated in the resin.

Example 3 (Formation of Colorant Particles According to the Second Aspect of the Invention by Microsuspension Method) 43.75 parts by weight of emulsifiable polymer A, 15.0 parts by weight of pigment (Pig. Blue 15), radical Using a sand grinder, 10.0 parts by weight of triethylene glycol dimethacrylate as a polymerizable monomer and 31.25 parts by weight of toluene were mixed to obtain a pigment-dispersed paste. In 100 parts by weight of this pigment dispersion paste, 0.45 parts by weight of azobisisobutyronitrile as a polymerization initiator was dissolved, and this was added to ion-exchanged water 24.
0 parts by weight, 1.2 parts by weight of sodium dioctyl sulfosuccinate as an emulsifier, and 0.6 parts by weight of polyoxyethylene cetyl ether (trade name "Newcol 1606", manufactured by Nippon Emulsifier Co., Ltd.) are mixed with stirring. An emulsion having an average particle diameter of 0.44 μm was obtained. After removing toluene from this emulsion, it was transferred to a 1-liter reaction vessel, and polymerization was continued for 5 hours while maintaining the temperature at about 70 ° C. No generation of aggregates was observed, and an emulsion in which colorant particles having an average particle size of 0.44 μm were dispersed was obtained. When the obtained colorant particles were observed with a transmission electron microscope, no detachment of the pigment was observed, and the pigment was encapsulated in the resin.

Example 4 (Formation of Colorant Particles According to the Second Aspect of the Invention by Microsuspension Method) 43.75 parts by weight of emulsifiable polymer A, 15.0 parts by weight of pigment (Pig. Red 146), radical Using a sand grinder, 10.0 parts by weight of trimethylolpropane triacrylate as a polymerizable monomer and 31.25 parts by weight of toluene were mixed to obtain a pigment-dispersed paste. In 100 parts by weight of this pigment dispersion paste, 0.45 parts by weight of azobisisobutyronitrile as a polymerization initiator was dissolved, and this was added to ion-exchanged water 24.
0 parts by weight and a mixed aqueous solution of 1.2 parts by weight of sodium dioctyl sulfosuccinate as an emulsifier were mixed with stirring to obtain an emulsion having an average particle diameter of 0.42 μm. After removing toluene from this emulsion, it was transferred to a 1-liter reaction vessel, and polymerization was continued for 5 hours while maintaining the temperature at about 70 ° C. No generation of aggregates was observed, and an emulsion in which colorant particles having an average particle diameter of 0.43 μm were dispersed was obtained. When the obtained colorant particles were observed with a transmission electron microscope, no desorption of the pigment was observed,
The pigment was encapsulated in the resin.

Example 5 (Formation of colorant particles according to the third aspect of the present invention by interfacial polymerization method) 56.25 parts by weight of emulsifiable polymer B, 15.0 parts by weight of pigment (Pig. Blue 15), and toluene 28 .75 parts by weight using a sand grinder to obtain a pigment dispersion paste. This pigment dispersion paste 1
00 parts by weight, 240 parts by weight of ion-exchanged water, and polyethylene glycol nonylphenyl ether as an emulsifier (trade name “Newcol 520”, manufactured by Nippon Emulsifier Co., Ltd.)
1.2 parts by weight of the mixed aqueous solution was mixed with stirring to obtain an emulsion having an average particle diameter of 0.42 μm. This emulsion was transferred to a 1-liter reaction vessel, and the temperature was adjusted to about 10 ° C. under ice cooling. To this, 22.4 parts by weight of a 10% by weight aqueous solution of tetraethylenepentamine as a crosslinking agent was dropped, and then toluene was removed from this emulsion under reduced pressure. No generation of aggregates was observed, and an emulsion of colorant particles having an average particle diameter of 0.44 μm was obtained. When the obtained colorant particles were observed with a transmission electron microscope, no detachment of the pigment was observed, and the pigment was encapsulated in the resin.

Example 6 (Formation of Colorant Particles According to the Fourth Aspect of the Present Invention by Interfacial Polymerization) Addition reaction of 43.75 parts by weight of emulsifiable polymer B, 15.0 parts by weight of pigment (Pig. Red 14) 10 parts by weight of tetramethylxylylene diisocyanate as a hydrophilic compound and 31.25 parts by weight of toluene were mixed using a sand grinder to obtain a pigment dispersion paste. 100 parts by weight of this pigment-dispersed paste, 240 parts by weight of ion-exchanged water, and polyethylene glycol nonylphenyl ether as an emulsifier (trade name "Newcol 5")
20 ") 1.2 parts by weight of a mixed aqueous solution was mixed with stirring to obtain an emulsion having an average particle diameter of 0.46 µm. Transfer this emulsion to a 1 liter reaction vessel,
The temperature was adjusted to about 10 ° C. under ice cooling. A 10% by weight aqueous solution of hexamethylene diamine as a crosslinking agent
4 parts by weight were added dropwise, and then the toluene was removed from the emulsion under reduced pressure. No generation of aggregates was observed, and an emulsion of colorant particles having an average particle diameter of 0.46 μm was obtained. When the obtained colorant particles were observed with a transmission electron microscope, no detachment of the pigment was observed, and the pigment was encapsulated in the resin.

Comparative Examples 1 to 6 In Examples 1 to 4, emulsions without radical polymerization were prepared by not heating, and the emulsions of Comparative Examples 1 to 4 were obtained. In Examples 5 and 6, emulsions without interfacial polymerization were prepared by adding no cross-linking agent, and used as emulsions of Comparative Examples 5 and 6. When the particles in these emulsions were observed with a transmission electron microscope, detachment of the pigment from the particles was observed.

Evaluation as Inkjet Recording Ink The emulsions obtained in Examples 1 to 6 and Comparative Examples 1 to 6 were evaluated as inks for inkjet recording. The evaluation as the ink for ink jet recording was performed by both the piezo method and the bubble jet method. As a result, Example 1
Regarding the samples No. to No. 6, clear high-density images were obtained.
On the other hand, in Comparative Examples 1 to 6, nozzle clogging occurred in any of the methods, and no image was obtained.

When the inks of Examples 1 to 6 were left outdoors for 20 days after printing, and the changes in the hue and saturation of the images were observed, almost no change was observed in any of them. On the other hand, as a comparison, printing was performed using a conventional dye-dissolving ink, and the resulting image was similarly left outdoors for 20 days and observed for changes. As a result, clear fading was observed.

[0065]

The colorant composition of the present invention and the colorant particles in the ink for ink jet recording have good stability in an aqueous medium, excellent storage stability, and are difficult to re-aggregate. Clogging hardly occurs.

Further, since the pigment is used, it has excellent weather resistance and water resistance, and does not cause bleeding or the like. Further, since the pigment is coated with the resin, when used as an ink for inkjet recording, the pigment is not aggregated on the paper surface, and a high-resolution and high-definition image can be obtained. Further, since the ink is fixed at the same time as the evaporation of the water on the paper, the image fixing strength is increased.

Since the resin encapsulating the pigment is obtained by polymerizing an emulsifying polymer, it is excellent in heat resistance, solvent resistance, water resistance and the like. In particular, heat resistance, solvent resistance, and water resistance can be further improved by forming crosslinked resin particles by polymerization.

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Claims (12)

[Claims] 1. A colorant composition comprising colorant particles in which a pigment is encapsulated by a resin obtained by polymerizing a polymer having a radical polymerizable group and having an emulsifying property in water. Stuff. 2. A colorant particle in which a pigment is encapsulated by a resin obtained by polymerizing a mixture of a polymer having a radically polymerizable group and having an emulsifying property in water and a radically polymerizable monomer. A colorant composition comprising: 3. A pigment is encapsulated by a resin obtained by reacting a polymer having a reactive group for addition polymerization and having emulsifying property with water with a crosslinking agent for addition polymerizing the polymer. A colorant composition comprising colorant particles. 4. A polymer comprising a polymer having a reactive group for addition polymerization and having emulsifiability in water and a compound having a reactive group for addition polymerization, and the polymer and the compound are subjected to addition polymerization. A colorant composition comprising colorant particles in which a pigment is encapsulated by a resin obtained by reacting a crosslinking agent for the colorant. 5. The method according to claim 1, wherein the emulsifying polymer is 8.0 × 10 ^−3.
The colorant composition according to any one of claims 1 to 4, which is a polymer having a hydrophilic group in an amount of from 1 to 1.4 x 10 ^-2 mol / g. 6. An ink jet recording ink comprising the colorant composition according to claim 1. Description: 7. The ink jet recording ink according to claim 6, wherein the average particle diameter of the colorant particles is 1 μm or less. 8. A step of mixing a polymer having a radical polymerizable group and having emulsifiability in water and a pigment to obtain a mixture in which the pigment is uniformly dispersed, and dispersing the mixture in water. A process of adding a water-soluble polymerization initiator to the emulsion, and then heating and polymerizing the inside of the emulsion to encapsulate the emulsion, thereby producing an emulsion. 9. A step of mixing a polymer having a radical polymerizable group and having emulsifiability in water, a pigment, and an oil-soluble polymerization initiator to obtain a mixture in which the pigment is uniformly dispersed. A method for producing an ink for inkjet recording, comprising: dispersing the mixture in water to form an emulsion; and heating the emulsion to polymerize the inside of the emulsion to encapsulate the emulsion. 10. The method for producing an ink for ink-jet recording according to claim 8, wherein the step of obtaining the mixture is a step of obtaining a mixture further mixed with a radical polymerizable monomer. 11. A polymer having a reactive group for addition polymerization and emulsifiable in water, and a pigment,
A step of obtaining a mixture in which the pigment is uniformly dispersed; a step of dispersing the mixture in water to form an emulsion; and a crosslinking agent for addition-polymerizing the polymer is added to the emulsion, and the inside of the emulsion is subjected to addition polymerization. A method for producing an ink for inkjet recording, comprising a step of encapsulating the ink. 12. The method according to claim 11, wherein the step of obtaining the mixture is a step of obtaining a mixture further mixed with a compound having a reactive group for addition polymerization.