JP2003082270A - Colored resin fine particle water dispersion, method of producing the same, colored resin fine particles, method for producing the same, ink, recording unit, ink cartridge, ink jet recorder and ink jet-recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide colored resin fine particles giving images having resistance to water, weather and scratch and high image concentration with high content of coloring components in the fine particles and is useful as an ink-coloring material, the aqueous dispersion colored resin fine particles, a method for producing the same and an ink that includes the fine particles as a coloring material and is suitable for ink jet recording. SOLUTION: The method for producing colored resin fine particles comprises the step (i) that the polymerizable unsaturated monomer, coloring agents, an emulsifier and a polymerization initiator are emulsified in an aqueous medium and the step (ii) that the polymerizable unsaturated monomer is polymerized. In this case, the step (i) is carried out in the presence of a water-insoluble organic solvent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to water resistance, weather resistance,
The present invention relates to an aqueous dispersion of colored resin fine particles, which gives an image having scratch resistance and high image density and is excellent in dispersion stability, and is useful as a coloring material for ink, and a method for producing the same. The ink using the colored resin fine particles is useful as an inkjet ink, and provides an image having water resistance, weather resistance, scratch resistance, and high image density, and is also excellent in dispersion stability. The present invention also provides colored resin fine particles, a method for producing the same, an ink, a recording unit, an ink cartridge,
The present invention relates to an inkjet recording device and an inkjet recording method.

[0002]

2. Description of the Related Art An ink jet recording method is one in which recording is performed by ejecting ink and adhering the ink to a recording medium such as paper. For example, Japanese Patent Publication No. 61-59911, Japanese Patent Publication No. 61-59912 and Japanese Patent Publication No. 61-5.
According to the ink jet recording method disclosed in Japanese Patent No. 9914, in which an electrothermal converter is used as the ejection energy supply means and thermal energy is applied to ink to generate bubbles to eject droplets, a recording head is provided. High density multi-orifice can be easily realized, and high resolution and high quality images can be recorded at high speed.

By the way, a water-soluble dye, for example, is used as a coloring material in an ink used in a conventional ink jet recording method, and a recorded image by such an ink is required to have further improved water resistance. ing. Further, water-soluble dyes up to now have insufficient weather resistance, and improvement in weather resistance is also required at the same time.

On the other hand, as a means for improving water resistance and weather resistance, there is a technique of using a pigment as a coloring material and dispersing it in water to prepare an ink. However, it is difficult to achieve both the dispersion stability of the pigment and the ejection stability of inkjet recording, and regarding the recorded image obtained by the pigment ink, there is still room for improvement, especially in scratch resistance on plain paper. It is left.

Many means for improving such problems have been proposed so far. For example, many techniques for adding a resin to a pigment ink have been proposed for the purpose of improving scratch resistance. However, there remains a problem that the viscosity of the ink increases due to the added resin. A technique for adding a particulate resin for the purpose of suppressing an increase in the viscosity of the ink has been proposed, but since the resin particles and the pigment are separately dispersed, it is possible to improve the scratch resistance of the obtained image. It was insufficient.

On the other hand, there has been proposed a technique of coating a pigment with a resin. Many techniques have been proposed to increase the adsorptivity to the pigment by controlling the hydrophobic and hydrophilic parts of the resin.However, in this production method, the resin floating without adsorbing to the pigment remains in the system. As a result, the viscosity of the ink may be increased, and the ejectability of the ink may be impaired.

As a production method in which such a free resin does not remain, a technique of coating the pigment with the resin by adding the pigment from the stage of the monomer before producing the resin and polymerizing in the presence of the pigment Proposals have been made. For example, JP-A-9
No. 279073 discloses a technique in which a coloring agent having an affinity for the unsaturated monomer is added and emulsion polymerization is carried out to obtain colored resin fine particles. Further, JP-A No. 11-12512 discloses ethylene. A technique for obtaining an inkjet ink by adding a pigment to a polyunsaturated monomer and performing emulsion polymerization is disclosed.

[0008]

However, according to the studies by the present inventors, it is very difficult to obtain dispersion stability at the time of emulsifying the unsaturated monomer and the pigment,
At this point, if the dispersion stability was insufficient, it was feared that the obtained dispersion would also have low stability.

For example, Japanese Patent Laid-Open No. 9-279073 mentioned above.
According to the description in the specification, the colored resin particles described in the publication can be manufactured according to a conventional emulsion polymerization method, and the monomer and the colorant are also used in Examples. After mixing, it is produced by emulsification in water to which an emulsifier is added and emulsion polymerization.

However, according to the study by the present inventors, since the polymerization proceeds while the mixed solution of the monomer and the colorant is sheared, the particle diameter is different due to the difference in shearing, and this method is uniform. It was speculated that it is difficult to obtain colored resin particles having a small particle size. According to the description of the specification, the inkjet ink described in JP-A-11-12512 creates a monomer oil droplet of 0.5 μm or less using a pipeline mixer or the like when emulsion polymerization is performed. The method is described.

However, according to the study by the present inventors, it is difficult to narrow the distribution of particle diameters only by mechanical dispersion, and when a strong mechanical shearing force is applied, the particle diameters of It was speculated that the stability with time was impaired.

When the colored resin fine particles are used as a coloring material for the ink jet ink, the upper limit of the amount of the colorant or resin that can be contained in the ink jet ink is determined in consideration of the ejection stability of the ink. Therefore, in order to obtain a sufficient image density in a printed image, colored resin fine particles containing a higher concentration of colorant are desired.

However, if an attempt is made to increase only the colorant, the solution becomes highly viscous during emulsification, and it becomes difficult to uniformly apply a shearing force. Therefore, a colored resin having a uniformly small particle size and excellent dispersion stability is obtained. It was speculated that the production of fine particles would be difficult. On the other hand, if the amount of the monomer is increased to alleviate the high viscosity at the time of emulsification, the concentration of the colorant relatively decreases, and the image density becomes low, which is not preferable.

As described above, the inventors of the present invention have studied the conventional techniques and found that in the ink jet ink, not only the water resistance and weather resistance of the image but also the scratch resistance of the image, the high image density, and the ink are further improved. It was concluded that in order to further improve the dispersion stability and the discharge stability of, it is necessary to develop a new technology that is different from the conventional technology.

Therefore, the object of the present invention is that it can be suitably used for the production of water-based inks, and it imparts excellent water resistance, weather resistance and scratch resistance to an image obtained by the water-based ink, and particularly An object of the present invention is to provide an aqueous dispersion of colored resin particles, which is capable of imparting high image density, and in which colored resin particles are stably dispersed, and a method for producing the same. Another object of the present invention is that it can be suitably used as a colorant for ink, and it imparts excellent water resistance, weather resistance, and scratch resistance to an image obtained by the ink, and has a particularly high image density. It is to provide a colored resin fine particle to which is provided and a method for producing the same. Another object of the present invention is to provide an ink which is excellent in water resistance, weather resistance and scratch resistance and gives an image having a particularly high image density. Another object of the present invention is an ink jet recording apparatus which is excellent in water resistance, weather resistance and scratch resistance and which can form an image having a particularly high image density, and a recording unit and ink which can be used for the same. To provide a cartridge.
Another object of the present invention is to provide an ink jet recording method which is excellent in water resistance, weather resistance and scratch resistance and which can form an image having a particularly high image density.

[0016]

Therefore, as a result of repeated studies by the present inventors, the problems of the method for producing colored resin fine particles can be solved while taking advantage of the advantage of using colored resin fine particles as the coloring material. The art was discovered and the object of the present invention was achieved.

That is, according to one embodiment of the present invention,
Colored resin fine particles having (i) a step of emulsifying a polymerizable unsaturated monomer, a colorant, an emulsifier and a polymerization initiator in an aqueous medium, and (ii) a step of polymerizing the polymerizable unsaturated monomer The method for producing an aqueous dispersion of colored resin fine particles, wherein the step (i) is performed in the coexistence of a water-insoluble organic solvent.

In the above invention, the emulsifier is a reactive emulsifier; the colorant is a pigment; the colorant is a pigment previously coated with a water-insoluble resin; the water-insoluble resin is a vinyl resin; At least one resin selected from the group consisting of cellulose resins and acrylic resins; the water-insoluble resin is a vinyl chloride-vinyl acetate copolymer; the polymerization initiator is a polymerizable unsaturated monomer and a non-polymerizable monomer. It is an oil-soluble polymerization initiator that is soluble in a mixed solution consisting of a water-soluble organic solvent, and the polymerization method is a suspension polymerization method; the water-insoluble organic solvent has a solubility in water of 100 parts by mass at 25 ° C. On the other hand, the amount of the organic solvent is 10 parts by mass, preferably 4 parts by mass or less; and the emulsification method is preferably a phase inversion emulsification method.

According to one embodiment of the present invention, (i)
It has a step of emulsifying a polymerizable unsaturated monomer, a colorant, an emulsifier, a polymerization initiator and a water-insoluble organic solvent in an aqueous medium, and (ii) a step of polymerizing the polymerizable unsaturated monomer. A method for producing fine colored resin particles is provided. In the above-mentioned present invention, a method is preferred which further comprises a step of removing at least one of the water-insoluble organic solvent and the aqueous medium after the above steps (i) and (ii). Further, according to another embodiment of the present invention, there is provided an aqueous ink containing the aqueous dispersion of colored resin fine particles. Further, according to another embodiment of the present invention, there is provided an ink containing the above-mentioned colored resin fine particles and a liquid medium. As the liquid medium of this ink, for example, an aqueous liquid medium or an oily liquid medium can be used. Further, these inks can be ink jet inks.

According to another embodiment of the present invention, it is characterized by comprising an ink containing portion containing the above-mentioned ink for ink jet and a head portion for ejecting the ink. A recording unit is provided. or,
According to another aspect of the present invention, there is provided an ink cartridge including an ink containing portion containing the above-described ink. Further, according to another embodiment of the present invention, an ink jet recording apparatus is provided with an ink storing section for storing the above ink jet ink and a recording head for discharging the ink. A recording device is provided. Further, according to another embodiment of the present invention, there is provided an inkjet recording method including a step of ejecting the above inkjet ink by an inkjet method.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to embodiments. The method for producing colored resin fine particles according to the embodiment of the present invention, at least a polymerizable unsaturated monomer, a colorant, an emulsifier and a polymerization initiator are emulsified in an aqueous medium, and this is polymerized to produce colored resin fine particles. In the method, a non-water-soluble organic solvent is allowed to coexist in the emulsification step. Here, it is preferable to use the phase inversion emulsification method in the emulsification step.

As an emulsification method, generally, an emulsifier is added to water, an oil component is added to this and the mixture is stirred with a disperser (hereinafter referred to as a direct emulsification method), or an emulsifier is added to the oil component. In addition, the method of throwing this in a large amount of water (henceforth a natural emulsification method) and the phase inversion emulsification method are mentioned.

The direct emulsification method is a method in which emulsion particles are crushed and emulsified by applying a strong shearing force using a disperser, and an emulsion can be obtained relatively easily. However, if the emulsion particles are not evenly sheared, the particle size distribution will become wider,
Further, it is known that the more time a strong shearing force is applied in order to obtain particles having a small particle size, the stability over time is deteriorated.
Further, the natural emulsification method emulsifies just by adding it to water, but a high degree of specialized knowledge is required for selecting an emulsifier, and it cannot be applied to all substances.

On the other hand, the phase inversion emulsification method is a method in which water is gradually added to liquid oils containing an emulsifier while stirring. When water is added to the oil droplets, a W / O type emulsion is created first, and the viscosity increases as the amount of water increases,
Eventually, the phase is changed to an O / W type emulsion. The feature of the phase inversion emulsification method is that it passes through this phase inversion point. That is, by stirring with sufficient shearing force at the phase inversion point at which the particles and the continuous phase in which the particles are dispersed are exchanged, it is possible to obtain an emulsion having a uniform small particle size with a very narrow particle size distribution.
Further, it is known that the emulsion obtained by the phase inversion emulsification method is particularly excellent in stability. The phase inversion emulsification method is generally performed manually using a beaker and a stirring rod. However, in the present invention, a non-water-soluble organic solvent is added in order to perform stirring at the phase inversion point more easily and uniformly. A disperser can also be used to obtain a more uniform and smaller particle size emulsion.

In the method for producing colored resin fine particles according to the embodiment of the present invention, a polymerizable unsaturated monomer, a colorant, an emulsifier, a non-water-soluble organic solvent and a polymerization initiator are used. Each constituent element will be described below.

(Polymerizable unsaturated monomer) Examples of the polymerizable unsaturated monomer include vinyl aromatic hydrocarbon and (meth).
Acrylic acid esters, (meth) acrylamide, alkyl-substituted (meth) acrylamide, N-substituted maleimide, maleic anhydride, (meth) acrylonitrile, methyl vinyl ketone, vinyl acetate, vinylidene chloride and the like can be mentioned.

Specific examples of vinyl aromatic hydrocarbons include:
For example, styrene, α-methylstyrene, o, m, p-
Examples thereof include chlorostyrene, p-ethylstyrene, divinylbenzene, etc., but are not limited thereto. Specific examples of the (meth) acrylic acid ester-based monomer include, for example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate. , Hexyl methacrylate, 2-ethylhexyl methacrylate, β-hydroxyethyl acrylate, γ-hydroxypropyl acrylate, δ-
Examples thereof include, but are not limited to, butyl hydroxyacrylate, β-hydroxymethacrylic acid ethyl ester, ethylene glycol dimethacrylic acid ester, and tetraethylene glycol dimethacrylic acid ester.

These polymerizable unsaturated monomers may be used alone or in combination.
Combinations of more than one species can be used. Of course, a small amount of a water-soluble monomer may be added and polymerized in order to improve the properties of the obtained colored resin fine particles depending on the application.

Examples of the water-soluble monomer include those having an anionic group such as a sulfonic acid group, a phosphoric acid group and a carboxylic acid group, and these acids include alkali metal salts such as sodium salt and ammonium. It may be in the form of salt, amine salt or the like or in the form of free acid. Suitable examples thereof are styrene sulfonic acid, sodium styrene sulfonate, 2-acrylamido-2-methylpropene sulfonic acid, 2-hydroxymethyl methacryloyl phosphate, 3-chloro-2-hydroxypropyl methacryloyl phosphate, acrylic acid, methacrylic acid, Examples include fumaric acid, crotonic acid, tetrahydroterephthalic acid, itaconic acid, maleic acid and the like.

(Colorant) As the colorant, those which can be dissolved or dispersed in the polymerizable unsaturated monomer are selected, and examples thereof include dyes, pigments, and processed pigments in which the pigment is provided with dispersibility. Pigments and processed pigments are preferably used because they have excellent weather resistance. In consideration of dispersibility in the polymerizable unsaturated monomer, a pigment previously coated with a water-insoluble resin compatible with the polymerizable unsaturated monomer used is particularly preferable. The pigment that can be used in the present invention is not particularly limited, but for example, the pigments described below can be preferably used.

First, as the carbon black as the black pigment, carbon black produced by a furnace method or a channel method, having a primary particle size of 15 to 40 mμ (n)
m), the specific surface area by the BET method is 50 to 300 m ² /
g, a DBP oil absorption amount of 40 to 150 ml / 100 g, a volatile content of 0.5 to 10% by mass, and a pH value of 2 to 9 are preferable.

Examples of such a device include No.
2300, No. 900, MCF88, No. 40, N
o. 52, MA7, MA8, No. 2200B (trade name; above, Mitsubishi Kasei), RAVEN1255 (trade name; made in Colombia), REGAL400R, REGAL
660R, MOGUL L (trade name; above, manufactured by Kyabot), Color Black FW1, Color
Black FW18, Color Black S1
70, Color Black S150, Print
Commercially available products such as ex 35 and Printex U (trade name; above, manufactured by Degussa) can be used. In addition, a new prototype may be used for the present invention.

Examples of the yellow pigment include C.I. I.
Pigment Yellow 1, C.I. I. Pigm
ent Yellow 2, C.I. I. Pigment
Yellow 3, C.I. I. Pigment Yell
ow 13, C.I. I. Pigment Yellow
16, C.I. I. Pigment Yellow 83 and the like.

Examples of magenta pigments include C.I. I.
Pigment Red 5, C.I. I. Pigment
Red 7, C.I. I. Pigment Red 1
2, C.I. I. Pigment Red 48 (Ca),
C. I. Pigment Red 48 (Mn), C.I.
I. Pigment Red 57 (Ca), C.I. I.
Pigment Red 112, C.I. I. Pigme
nt Red 122 and the like. As the magenta pigment, a quinacridone pigment is particularly preferable.

Examples of cyan pigments include C.I. I. P
igment Blue 1, C.I. I. Pigment
Blue 2, C.I. I. Pigment Blue
3, C.I. I. Pigment Blue 15: 3,
C. I. Pigment Blue 16, C.I. I. P
igment Blue 22, C.I. I. Vat Bl
ue 4, C.I. I. Vat Blue 6 etc. are mentioned. Phthalocyanine pigments are particularly preferable as the cyan pigment. Further, regarding the coloring materials of any of the above-mentioned colors, those newly manufactured for the present invention can be used.

The processed pigment that can be used in the present invention is selected to be compatible with the polymerizable unsaturated monomer used, and in particular, the surface treatment is performed to improve the dispersibility in the polymerizable unsaturated monomer. Those that have been subjected to are preferable. Further, a pigment whose surface is previously coated with a water-insoluble resin compatible with the polymerizable unsaturated monomer is preferable. Specifically, it is called a color chip (trade name; Taihei Chemical Co., Ltd., Taisei Kako Co., Ltd.) in which a pigment and a resin are kneaded under heating with two rolls, or Microlith (trade name; Ciba Specialty Chemicals). Commercially available processed pigments can be used. It is also possible to use a pigment obtained by any known method such as a simple coacervation method in which a pigment is dispersed in a resin solution and a poor solvent is added thereto to precipitate the resin on the pigment surface.

The water-insoluble resin coating the pigment is freely selected from the adsorptivity to the pigment used and the solubility to the polymerizable unsaturated monomer used, but especially vinyl chloride resin,
Vinyl acetate resin, vinyl chloride-vinyl acetate copolymer resin,
Vinyl resins such as polyvinyl acetal resins, cellulose resins and acrylic resins are preferable, and among them, vinyl chloride-vinyl acetate copolymer resins are most suitable for stabilizing the fine particles of the pigment in the polymerizable unsaturated monomer. If desired, two or more water-insoluble resins may be used in combination.

(Emulsifier) The emulsifier used in the present invention may be nonionic, anionic or both. However, a large amount of an emulsifier is often used in the phase inversion emulsification method, which is a feature of the present invention, and the emulsifier free is also reduced in the dispersion of the generated colored resin fine particles to control the permeability of the ink. To improve the water resistance of the recorded image, it is preferable to use a reactive emulsifier. The reactive emulsifier is an anionic or nonionic emulsifier having at least one unsaturated double bond in the molecule, and examples thereof include sulfosuccinic acid ester type and alkylphenol ether type.

Examples of the nonionic reactive emulsifier include those having a polyoxyethylene group in the molecule.
Specifically, polyoxyethylene allyl glycidyl nonyl phenyl ether "ADEKA REASOAP NE" (trade name; manufactured by Asahi Denka Co., Ltd.), polyoxyethylene nonyl propenyl ether "Aqualon RN" (trade name; Dai-ichi Kogyo Seiyaku ( Co., Ltd.) and the like.

Examples of the anionic reactive emulsifier include sulfonic acid (salt) type, carboxylic acid (salt) type, phosphoric acid ester type and the like. Specifically, it is a sulfate ester salt of polyoxyethylene allyl glycidyl nonyl phenyl ether, "ADEKA REASOAP SE" (trade name; manufactured by Asahi Denka Co., Ltd.), and a sulfate ester salt of polyoxyethylene nonyl propenyl ether. "Aqualon HS" and "Aqualon BC" (trade name; manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)
Etc., and those having other structures include "Eleminol JS-2", "Eleminol RS-30" (trade name; manufactured by Sanyo Chemical Industry Co., Ltd.), "Latemul" (trade name;
Examples include Kao Corporation's), “New Frontier” (trade name; manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and the like, but are not limited thereto. These reactive emulsifiers can be used alone or in combination of two or more, or can be used in combination with a usual emulsifier. The amount of such an emulsifier used is 5 to 50% by mass based on the mass of all the monomers.
Is preferable, and more preferably 10 to 40% by mass.
Further, in order to improve the emulsifying property of the solution, a pH adjusting agent may be added.

(Non-Water-Soluble Organic Solvent) As the non-water-soluble organic solvent, any solvent which is incompatible with water may be used, but the solubility in water at 25 ° C. is 10 with respect to 100 parts by mass of water. It is preferably not more than 4 parts by mass, more preferably not more than 4 parts by mass. When the solubility in water exceeds 10 parts by mass, phase separation or a colorant precipitates, which is not preferable because the emulsification is insufficient.

Preferred water-insoluble organic solvents include, for example, ethyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, n-propyl acetate, isopropyl acetate, n-hexyl acetate, benzyl acetate, ethyl propionate, Alkyl esters such as n-propyl propionate, isopropyl propionate, n-butyl propionate, isobutyl propionate and sec-butyl propionate, methyl n-butyl ketone, methyl isobutyl ketone, 2-heptanone, diethyl ketone, di-n -Ketones such as propyl ketone and di-n-butyl ketone, di-n
-Propyl ether, diisopropyl ether, di-n
-Ethers such as butyl ether and anisole, aromatics such as toluene, xylene and chlorobenzene, alcohols such as 1-hexanol and 1-heptanol, chloride n
-Butyl, chloroform, hexane, octane, and other aliphatic compounds are listed, but of course the present invention is not limited thereto.

These water-insoluble organic solvents may be used alone or in admixture of two or more. These water-insoluble organic solvents are used in a range that alleviates the increase in the viscosity of the solution during phase inversion emulsification, but the water-insoluble organic solvent 30 parts by mass to 500 parts by mass relative to 100 parts by mass of the monomer solution. It is preferably used within the range of parts. If the amount is less than 30 parts by mass, the viscosity of the monomer solution increases greatly during emulsification, which is not preferable.
On the other hand, if it exceeds 500 parts by mass, the amount of emulsifier required for emulsification increases, and as a result, the water resistance and image density of the obtained image decrease, which is not preferable. When removing the water-insoluble organic solvent from the reaction solution after polymerization, a solvent having a boiling point lower than the boiling point of water is preferably used.

(Polymerization Initiator) As the polymerization initiator, water-soluble or oil-soluble persulfates, peroxides and azo compounds can be used. Among them, the polymerization method is preferably carried out by suspension polymerization in which the monomer does not move, and therefore a polymerization initiator soluble in the monomer is preferably used. For example, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxyl benzoate, 2,2-azobisisobutyronitrile, 2,2-azobis (2- Diaminopropane) hydrochloride, 2,2-azobis (2,4-
Dimethyl valeronitrile) and the like.

Next, the step of polymerizing the polymerizable unsaturated monomer constituting the method for producing the aqueous dispersion of colored resin fine particles according to the embodiment of the present invention will be described. In the polymerization step, for example, an emulsion polymerization method using a pre-emulsification method and a suspension polymerization method can be used. The emulsion polymerization method and the suspension polymerization method are similar in that they use water as a medium, but the emulsion polymerization method uses a polymerization initiator insoluble in the monomer as the polymerization initiator, while the suspension polymerization method uses The difference is that a polymerization initiator that is soluble in the monomer is used. As a result, emulsion polymerization and suspension polymerization follow completely different polymerization mechanisms.

That is, in the suspension polymerization method, the polymerization proceeds in each monomer particle, whereas in the emulsion polymerization method, the polymerization initiator is added to the micelle formed by the emulsifier in the system and a small amount of the monomer. Polymerization is initiated by the diffusion of the monomer, and the monomer is supplied to this from the monomer oil droplets to promote the polymerization. In the present invention, it is preferable to obtain colored resin fine particles by forming particles of a monomer containing a colorant by pre-emulsification using a phase inversion method, and polymerizing the particles while keeping the shape as it is. . Therefore, it is preferable to carry out the suspension polymerization method, which is a system in which the migration of the monomer from the monomer particles does not occur.

In the conventional suspension polymerization method, a stabilizer such as polyvinyl alcohol was added in order to keep the monomer in a stable dispersed state, and the polymerization was carried out while vigorously stirring to disperse the monomer. Therefore, it has been generally known that polydisperse particles having a large particle size can be obtained as compared with emulsion polymerization. On the other hand, by using the method of the present invention, stable and uniform monomer particles having a small particle size can be formed by pre-emulsification using the phase inversion emulsification method, and particles obtained by suspension polymerization of the same. Similarly, it is presumed that a uniform and small particle size can be obtained.

The average particle size of the colored resin fine particles obtained after the polymerization is preferably 500 nm or less, more preferably 200 nm or less. When the average particle size of the colored resin fine particles is large, sedimentation easily occurs due to long-term storage, and it is difficult to maintain dispersion stability. In order to form colored resin fine particles having an average particle diameter within the above range, the average particle diameter of the monomer particles after phase inversion emulsification is 5
It is preferably 00 nm or less, and further 200 nm
The following is preferable. In addition, what is directly obtained by the above-mentioned method is that the colored resin fine particles are dispersed in an aqueous medium to be precise, and in the present invention, this is referred to as an aqueous dispersion of the colored resin fine particles. When an ink is produced using the colored resin fine particles according to the present invention, an aqueous dispersion of the colored resin fine particles may be used as it is, depending on the composition of the ink to be obtained. Water is removed from the water dispersion by a standard method (for example, distillation, centrifugation, filtration, spray drying, etc.) and taken out as colored resin fine particles, and then dispersed again in an appropriate solvent, for example, an aqueous medium or an oily medium. It may be made into ink.

The colored resin fine particles produced by the present invention have good water resistance, and the ink image obtained by using them has good weather resistance and scratch resistance, and is excellent in dispersion stability. It can be suitably used as an ink for use. In particular, since the dispersibility in water is good,
It is preferably used as a water-based inkjet ink.

The ink using the colored resin fine particles of the present invention is constituted by maintaining the dispersed state of the colored resin fine particles in the aqueous medium. Further, it is preferable that at least water is contained as a constituent component of the aqueous medium. The proportion of water in the total mass of the ink is, for example, 20 to 95 mass%, particularly 40 to 95 mass%, and further preferably 60 to 95 mass%.

The aqueous medium may contain a water-soluble organic solvent. The content of the water-soluble organic solvent in the ink is
It is 2 to 60 mass% of the total weight of the ink. Specific water-soluble organic solvents include, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol and the like having 1 to 4 carbon atoms.
Alkyl alcohols, amides such as dimethylformamide and dimethylacetamide, ketones such as acetone, ethers such as tetrahydrofuran and dioxane,
Polyalkylene glycols such as polyethylene glycol and polypropylene glycol, alkylene groups such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol and diethylene glycol Lower alkyl ethers of polyhydric alcohols such as alkylene glycols having 2 to 6 carbon atoms, glycerin, ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, N-methyl-2-pyrrolidone , 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl sulfoxide, 2
Examples include cyclic amide compounds such as -pyrrolidone and ε-caprolactam, and imide compounds such as succinimide.

The ink according to the present invention is preferably used in an ink jet recording method for recording an image by ejecting the ink from a recording head by thermal energy or mechanical energy and adhering it to a recording medium. When the ink according to this aspect is particularly suitable for ink jet recording use, the surface tension of the ink at 25 ° C. is 15 to 60 dyn / cm (mN / mN /
m), 20 to 50 dyn / cm (mN / m), and a viscosity of 15 cP (mPa · s) or less, particularly 10 cP (m).
Pa · s) or less is preferable. Further, the pH range is preferably 3 to 11, and a more preferable range is 3.
It is 5 to 10.

Specific examples of ink compositions that can achieve such characteristics include various inks used in Examples described later. In addition to the colored resin fine particles obtained as described above, various additives such as a surfactant, a pH adjusting agent and a mildew proofing agent may be added to the ink according to the present aspect. The recording medium used in the recording method using the ink according to this aspect is not particularly limited, and may be plain paper such as copy paper or bond paper, or a coat specially prepared for inkjet recording. Examples include paper, glossy paper, OHP film and the like.

The ink of the present invention is particularly suitable for use in an ink jet recording system in which droplets are ejected by the action of heat energy for recording, but it can also be used as another ink jet recording method or a general writing tool. There is no end.

A recording apparatus suitable for recording using the ink of the present invention is an apparatus for applying thermal energy corresponding to a recording signal to the ink in the chamber of the recording head and generating a droplet by the energy. To be

An example of the structure of the recording head, which is the main part, is shown in FIGS. 1, 2 and 3. The head 13 is made of glass, ceramics, a plastic plate, or the like having a groove 14 through which ink passes, and a heating head 15 having a heating resistor used for heat-sensitive recording (a head is shown in the drawing, but is not limited to this. It is not a thing) and is obtained by adhering. The heating head 15 has a protective film 1 formed of silicon oxide or the like.
6, aluminum electrodes 17-1 and 17-2, a heating resistor layer 18 made of nichrome, a heat storage layer 19, and a substrate 20 having a good heat dissipation property such as alumina.

The ink 21 is a discharge orifice (fine hole).
22 is filled, and the meniscus 23 is generated by the pressure P.
Is formed. FIG. 4 shows an example of an ink jet recording apparatus incorporating the head as described above. In FIG. 4, 61 is a blade as a wiping member,
One end thereof is held by the blade holding member to become a fixed end, which is in the form of a cantilever. Blade 61
Is arranged at a position adjacent to the recording area of the recording head, and in the case of the example shown in FIG. 4, is held in a protruding form in the movement path of the recording head. Reference numeral 62 denotes a cap, which is disposed at a home position adjacent to the blade 61, and has a configuration in which it moves in a direction perpendicular to the moving direction of the recording head and comes into contact with the ejection surface to perform capping. Furthermore,
Reference numeral 63 denotes an ink absorber provided adjacent to the blade 61, and like the blade 61, is held in a form protruding in the moving path of the recording head.

The blade 61, the cap 62, and the absorber 63 constitute an ejection recovery unit 64, and the ejection recovery unit 64 removes water, dust, and dust from the ink ejection port surface by the blade 61 and the absorber 63. Done. Reference numeral 65 denotes a recording head having ejection energy generating means for ejecting ink to a recording material facing the ejection port surface where the ejection ports are arranged to perform recording, and 66 denotes a recording head 65 in which the recording head 65 is mounted. It is a carriage for moving the. The carriage 66 slidably engages with the guide shaft 67, and a part of the carriage 66 is connected to a belt 69 driven by a motor 68 (not shown). As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and its adjacent area.

Reference numeral 51 is a paper feed section for inserting a recording material, and 52 is a paper feed roller driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the ejection opening surface of the recording head, and as recording progresses, the recording material is ejected to the ejection unit provided with the ejection roller 53. In the above-described configuration, when the recording head 65 returns to the home position after the recording is completed, the cap 62 of the ejection recovery unit 64 is retracted from the moving path of the recording head 65.
The blade 61 projects into the movement path. As a result,
The ejection port surface of the recording head 65 is wiped. In addition,
When the cap 62 comes into contact with the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to project into the moving path of the recording head.

When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are at the same positions as the above wiping positions. As a result, even during this movement, the ejection port surface of the recording head 65 is wiped. The above-mentioned movement of the recording head to the home position is performed not only at the end of recording and at the time of ejection recovery, but also at the home position adjacent to the recording area at a predetermined interval while the recording head moves in the recording area for recording. Then, with this movement, the wiping is performed.

FIG. 5 is a sectional view showing an example of an ink cartridge 45 in which the head is provided with an ink supply member, for example, an ink storage portion which stores ink supplied via a tube. Here, reference numeral 40 is an ink containing portion containing the supply ink, for example, an ink bag, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into this stopper 42, the ink in the ink bag 40 can be supplied to the head. Reference numeral 44 is an ink absorber that receives waste ink.

The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separated as described above, and one in which they are integrated as shown in FIG. 6 is also preferable. Used. In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink containing portion containing ink, for example, an ink absorber is contained, and the ink in the ink absorber has a head portion having a plurality of orifices. The ink is ejected from 71 as an ink droplet. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the recording unit with the atmosphere. The recording unit 70 is used in place of the recording head 65 shown in FIG. 4, and is detachable from the carriage 66.

[0063]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the scope of the present invention is not limited by these Examples. In the following description, "part" or "%" is based on mass unless otherwise specified.

[Examples 1 to 3 and Comparative Example 1 Preparation and Evaluation Results of Aqueous Dispersion of Fine Colored Resin Particles] (Preparation of Aqueous Dispersion of Fine Colored Resin Particles) <Example 1> Styrene was used as the polymerizable unsaturated monomer. 4 parts and 6 parts of 2-ethylhexyl acrylate, as a colorant, a processed pigment "Microlith Blue 4GKP" (brand name; phthalocyanine blue (CI.PB15: 3) and a vinyl chloride-vinyl acetate copolymer). Pigment concentration 50%: Ciba Specialty Chemicals Co., Ltd. 4
Parts, reactive emulsifier "Eleminol JS-"
2 "(trade name; manufactured by Sanyo Kasei Co., Ltd.), 20 parts of ethyl acetate (solubility in water at 25 ° C .; about 8%) as a water-insoluble organic solvent, and 2,2 as a polymerization initiator. −
0.36 parts of azobisisobutyronitrile were mixed. While stirring the above mixture with a glass rod, water was gradually added, and when the viscosity was increased, the mixture was further vigorously stirred with the glass rod. The mixture was sufficiently stirred at the phase inversion point, water was further added to invert the phase, and water was further added to prepare components so that the components other than water were 40% to obtain an emulsion. Polymerization device for the emulsion (polymerization device equipped with stirrer, reflux condenser and nitrogen gas inlet pipe)
The temperature was raised to 75 ° C. in a nitrogen stream and polymerization was carried out for 24 hours. After completion of the polymerization, ethyl acetate was removed by distillation under reduced pressure to obtain an aqueous dispersion A of fine colored resin particles.

Example 2 As a water-insoluble organic solvent, methyl isobutyl ketone (solubility in water at 25 ° C .;
Aqueous dispersion B of colored resin fine particles was obtained in the same manner as in Example 1 except that 20 parts (about 2%) was used.

<Example 3> N-butyl acetate (solubility in water at 25 ° C; about 1%) was used as a water-insoluble organic solvent.
A colored resin fine particle water dispersion C was obtained in the same manner as in Example 1 except that 20 parts were used.

Comparative Example 1 A polymer dispersant Di was added to a mixed solution of 4 parts of methyl methacrylate and 6 parts of n-butyl acrylate.
A solution in which 1 part of sperbyk161 (trade name; manufactured by BYK Japan Japan Ltd.) in terms of solid content is dissolved, 1 part of phthalocyanine blue (CI.PB15: 3), and 10 parts of glass beads having a diameter of 0.5 mm. In addition, it was dispersed by a sand mill for 16 hours.

After removing the glass beads, 0.36 part of 2,2-azobisisobutyronitrile was mixed as a polymerization initiator. As an emulsifier, 2 parts of a reactive emulsifier "Eleminol JS-2" (trade name; manufactured by Sanyo Chemical Industry Co., Ltd.) was dissolved in 53.44 parts of water, and the above colorant solution was added to a homomixer. And stirred to obtain an emulsion. The obtained emulsion is put into a polymerization device (a polymerization device equipped with a stirrer, a reflux condenser and a nitrogen gas inflow pipe), and at 75 ° C. under a nitrogen stream.
The temperature was raised to 0 ° C. and polymerization was carried out for 24 hours to obtain an aqueous dispersion D of fine colored resin particles.

(Evaluation Results of Aqueous Dispersion of Colored Resin Fine Particles) Pigment Concentration The mass percentage of the pigment contained in the solid content of the aqueous dispersion of colored resin fine particles is shown.

Particle size The average particle size of the colored resin fine particle water dispersion was measured by a dynamic light scattering method (trade name ELS-8000; manufactured by Otsuka Electronics Co., Ltd.).

Storage-stable colored resin fine particle water dispersion is sealed in a fluororesin container,
Stored at 60 ° C for 1 month. The state of precipitation and gelation was visually evaluated. The results were evaluated according to the criteria shown below. A: Almost no gelation or precipitate was observed. B: A slight gelation or precipitate is observed. C: Considerable precipitate and gelation are observed. The evaluation results are shown in Table 1 below.

[0072]

[Examples 4 to 6 and Comparative Example 2 Ink Preparation and Evaluation Results] (Preparation of Ink) The inks of Examples 4 to 6 were prepared using the colored resin fine particle aqueous dispersions A to C. Glycerin 10
Parts, 5 parts of ethylene glycol, 5 parts of trimethylolpropane, 1 part of acetylenol EH, and 39 parts of water, and 40 parts of each of the obtained colored resin fine particle water dispersions A to C were added and stirred. This was filtered to obtain the inks of Examples 4-6. An ink of Comparative Example 2 was obtained by using the colored resin fine particle water dispersion D in the same manner as in Examples 4 to 6.

(Results of Ink Evaluation) The inks of Examples 4 to 6 and Comparative Example 2 thus prepared are mounted on a color BJ printer (trade name BJC-420J; manufactured by Canon Inc.), and a BC-21 cartridge is mounted. BJC-420J plain paper, 360 × 360DP, by filling this ink tank into BJC-420J.
Recording paper in I, HQ mode (Pro Photo Photo Paper PR
-101; printed by Canon Inc.). The evaluation results are shown in Table 2 below.

-Storage stability The above ink was sealed in a fluororesin container and kept at 60 ° C for 1 hour.
After storage for a month, the presence or absence of gelation and sediment was visually evaluated. The evaluation results are classified as follows. A: Almost no gelation or sedimentation. B: A slight gelation or precipitate was observed, but there was no problem in practice. C: Gelation and sediment are severe.

Ejection stability A 1-dot vertical line was printed on a recording paper at the beginning of using the BC-21 cartridge. Further, the text was printed until the BC-21 cartridge was used up, and a vertical line of 1 dot was printed on another recording paper using the cartridge just before the use. These recording papers were visually observed from a distance of 25 cm, and the printing result by the cartridge at the beginning of use and the printing result by the cartridge at the end of use were evaluated according to the following criteria. A: There is no difference between the two. B: Although a dot landing deviation is recognized in a part of the vertical line printed by the cartridge just before the end of use, it can be recognized as a straight line. C: The dot landing deviation is clearly recognized on the vertical line printed by the cartridge just before the end of use, and the vertical line is misaligned.

After leaving a water-resistant solid image for 24 hours after printing, a reflection densitometer RD
It measures using -918 (made by a Macbeth company). This measurement product is allowed to stand in tap water for 5 minutes, the reflection density after water drying is measured, and the residual ratio of the reflection density before the water resistance test and after the water resistance test is obtained and used as a scale of water resistance. The evaluation results are classified as follows. A: The residual ratio of image density is 80% or more. B: The residual ratio of image density is 70% or more and less than 80%. C: The residual ratio of image density is less than 70%.

12 hours after the abrasion-resistant image is printed, sillbon paper is placed on the printed paper, and one side is 5 cm and the weight is 1 kg.
When the sillbon paper was pulled after the weight was placed, whether or not the non-printed portion (white portion) of the recording paper and the rubbed paper rubbed the printed portion was stained was visually observed. A: There is no stain on the white part and the sillbon paper. B: Only the sillbon paper is stained. C: There are stains on both the white part and the sillbon paper.

Image density The solid image was left for 12 hours after printing and then measured using a reflection densitometer Macbeth RD-918. The evaluation results are classified as follows. A: Image density is 1.1 or more. B: Image density is 0.7 or more and less than 1.1. C: Image density is less than 0.7.

[0080]

[0081]

As described above, according to the present invention, it is useful as a coloring material for inks, which gives an image having water resistance, weather resistance, scratch resistance, high image density and is excellent in dispersion stability. It is possible to provide fine colored resin fine particles or an aqueous dispersion thereof.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a head portion of an inkjet recording apparatus.

FIG. 2 is a cross-sectional view of a head portion of an inkjet recording device.

FIG. 3 is an external perspective view of a head portion of the inkjet recording apparatus.

FIG. 4 is a perspective view showing an example of an inkjet recording apparatus.

FIG. 5 is a vertical sectional view of an ink cartridge.

FIG. 6 is a perspective view of a recording unit.

[Explanation of symbols]

13: Head 14: groove 15: Heating head 16: Protective film 17-1, 17-2: Aluminum electrodes 18: Heating resistor layer 19: Heat storage layer 20: substrate 21: Ink 22: Discharge orifice (fine hole) 23: Meniscus 24: Ink droplet 25: Recording material 26: Multi nozzle 27: Glass plate 28: Heating head 40: Ink bag 42: Stopper 44: Ink absorber 45: Ink cartridge 51: Paper feed section 52: Paper feed roller 53: Paper ejection roller 61: Wiping member (blade) 62: Cap 63: Ink absorber 64: Discharge recovery unit 65: recording head 66: Carriage 67: Guide shaft 68: Motor 69: Drive belt 70: Recording unit 71: Head part 72: Air communication port

Continued front page    (72) Inventor Hideyuki Takai             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Masaaki Hiro             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Makiko Endo             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 2C056 EA13 FC01                 2H086 BA53 BA54 BA55 BA59 BA60                 4J037 AA02 CC02 CC16 EE03 EE12                       EE28                 4J039 AB02 AD09 BA04 BE01 BE02                       GA24

Claims (23)

[Claims] 1. A step of (i) emulsifying a polymerizable unsaturated monomer, a colorant, an emulsifier and a polymerization initiator in an aqueous medium, and (ii) a step of polymerizing the above polymerizable unsaturated monomer. A method for producing a colored resin fine particle water dispersion, which comprises carrying out the step (i) in the presence of a water-insoluble organic solvent. 2. The method for producing an aqueous dispersion of colored resin fine particles according to claim 1, wherein the emulsifier is a reactive emulsifier. 3. The method for producing an aqueous dispersion of colored resin fine particles according to claim 1, wherein the colorant is a pigment. 4. The method for producing an aqueous dispersion of colored resin fine particles according to claim 1, wherein the colorant is a pigment which is previously coated with a water-insoluble resin. 5. The method for producing an aqueous dispersion of colored resin fine particles according to claim 4, wherein the water-insoluble resin is at least one resin selected from the group consisting of vinyl resins, cellulose resins and acrylic resins. 6. The method for producing an aqueous dispersion of colored resin fine particles according to claim 4, wherein the water-insoluble resin is a vinyl chloride-vinyl acetate copolymer. 7. The polymerization initiator is an oil-soluble polymerization initiator soluble in a mixed solution of a polymerizable unsaturated monomer and a water-insoluble organic solvent, and the polymerization in the step (ii) is suspended. The method for producing an aqueous dispersion of colored resin fine particles according to claim 1, which is a turbid polymerization method. 8. The aqueous dispersion of colored resin fine particles according to claim 1, wherein the water-insoluble organic solvent is an organic solvent whose solubility in water at 25 ° C. is 10 parts by mass or less relative to 100 parts by mass of water. Production method. 9. The aqueous dispersion of colored resin fine particles according to claim 1, wherein the water-insoluble organic solvent is an organic solvent whose solubility in water at 25 ° C. is 4 parts by mass or less relative to 100 parts by mass of water. Production method. 10. The emulsification method in the step (i) comprises:
The method for producing an aqueous dispersion of colored resin fine particles according to claim 1, which is a phase inversion emulsification method. 11. An aqueous dispersion of colored fine resin particles, which is obtained by the method according to any one of claims 1 to 10. 12. An ink comprising at least an aqueous dispersion of colored resin fine particles according to claim 11. 13. (i) A polymerizable unsaturated monomer, a colorant,
A method for producing colored resin fine particles, which comprises a step of emulsifying an emulsifier, a polymerization initiator and a water-insoluble organic solvent in an aqueous medium, and (ii) a step of polymerizing the polymerizable unsaturated monomer. . 14. The method for producing colored resin fine particles according to claim 13, further comprising a step of removing at least one of the water-insoluble organic solvent and the aqueous medium after the steps (i) and (ii). 15. Colored resin fine particles obtained by the method for producing colored resin fine particles according to claim 13 or 14. 16. An ink containing the colored resin fine particles according to claim 15 and a liquid medium. 17. The ink according to claim 16, wherein the liquid medium is aqueous. 18. The ink according to claim 16, wherein the liquid medium is oily. 19. The ink according to any one of claims 12 and 16 to 18, which is for inkjet recording. 20. A recording unit, comprising: an ink containing portion containing the ink according to claim 19; and a head portion for ejecting the ink. 21. An ink cartridge comprising an ink containing portion containing the ink according to any one of claims 12 and 16 to 19. 22. An ink jet recording apparatus comprising: an ink containing portion containing the ink according to claim 19; and a recording head for ejecting the ink. 23. An ink jet recording method comprising a step of ejecting the ink according to claim 19 by an ink jet method.