JP4727963B2 - Method for producing aqueous fine particle dispersion composition - Google Patents

Description

  The present invention relates to an aqueous fine particle dispersion composition used for ink, paint, and the like.

  Compositions in which fine particles are dispersed in a medium are widely used as materials for various inks and paints. Various particles are selected depending on the purpose of use. For example, in the case of coloring such as ink for ink jet printers and paints, various organic pigments, carbon black, metal oxides, etc. are also used for magnetic recording media. Magnetic iron oxide and metallic iron are used for magnetic coatings, and aromatic compounds and titanium oxide are used for ultraviolet protection and photocatalytic coating.

  Of these, organic materials have inferior durability against light and ozone.For example, organic pigments have higher weather resistance than dyes, but in severe environments such as direct sunlight. The weather resistance of is not sufficient. On the other hand, as a dispersion medium, an organic solvent is used when quick drying is required. However, an aqueous medium has been increasing in consideration of the environment and safety. Accordingly, a dispersion composition in which inorganic particles are stably dispersed in an aqueous medium is desired as a raw material used in practical inks and paints having high weather resistance.

  Inorganic particles are generally hydrophilic except for carbon black and the like. Therefore, although it has a high affinity for an aqueous medium as it is, the specific gravity is large, so that a stable dispersion composition cannot be obtained simply by mixing. Accordingly, attempts have been made to stabilize the dispersion with various polymer dispersants for the purpose of further increasing the affinity for the aqueous medium and preventing the particles from directly contacting and aggregating. In particular, a block copolymer (copolymer) having a hydrophobic part and a hydrophilic part easily forms a capsule in which the hydrophilic part and the hydrophobic part form a layer in water, and is suitable for coating of particles.

For example, in Patent Document 1 and Patent Document 2, a pigment is dispersed using a block copolymer having an acrylic ester or the like as a monomer, and in Patent Document 3, a method of extending a hydrophobic polymer to a resin having a hydrophilic portion. Is disclosed. Patent Document 4 discloses a method in which a reactive dispersant is attached to a pigment surface and dispersed, and then a hydrophobic portion and then a hydrophilic portion are elongated from the dispersant by polymerization. Although it is possible to disperse various particles by these methods, in any of the examples, the main targets are organic pigments and carbon black, and the effect on inorganic particles having a hydrophilic surface originally is From the viewpoint of the structure of the polymer dispersant used, it is not sufficient.
JP 2003-49110 A JP 2003-246958 A JP 2003-246804 A JP 2003-128976 A

  In view of the above situation, an object of the present invention is to provide a fine particle dispersion composition in which inorganic fine particles having high weather resistance are stably dispersed in an aqueous medium.

  The above problems are solved by the present invention described below. That is, the present invention provides a composition in which inorganic fine particles having hydrophilic surfaces are dispersed in an aqueous medium, wherein the inorganic fine particles contain at least a hydrophilic segment and a segment obtained by hydrophilizing a hydrophobic segment by post-treatment. An aqueous fine particle dispersion composition is provided which is coated with a block copolymer having a polyvinyl ether structure.

In the present invention, it is preferable that the hydrophobic segment is hydrophilized after the inorganic fine particles and the block copolymer are dispersed in a non-aqueous medium. The fine particles may be a metal or a metal compound. In addition, the present invention provides an ink for an ink jet printer, which contains the fine particle dispersion composition as a color material.

  According to the present invention, a fine particle dispersion composition having high dispersion stability in which inorganic fine particles are dispersed in an aqueous medium can be obtained. Furthermore, an ink having high ejection stability could be obtained by using the fine particle dispersion composition.

  Next, the present invention will be described in more detail with reference to preferred embodiments. The block copolymer used in the present invention functions as a dispersant for stably dispersing fine particles in the fine particle dispersion composition, and after being applied to a medium such as paper as ink or paint, the fine particles are fixed to the medium. It acts as a binder.

  The block copolymer used in the present invention has a hydrophilic block (A) for adhering to hydrophilic inorganic fine particles on the surface, and is initially hydrophobic but can be hydrophilized by post-treatment and dissolved in an aqueous medium. At least the block (B) is included. Further, the block copolymer used in the present invention may contain a hydrophobic block (C) in order to strengthen the interaction between the copolymers and form a strong capsule.

  The arrangement of each block in the block copolymer is such that the hydrophilic block (A) and the block (B) that exhibits hydrophilicity by post-treatment are present at both ends of the polymer from the viewpoint of enhancing the dispersibility of the hydrophilic fine particles. For example, an AB type or an ACB type is preferable. A, B, and C represent homopolymer or copolymer blocks.

A preferred block copolymer used in the present invention comprises a polymer or copolymer of vinyl ether monomers. These block copolymers preferably have a repeating unit represented by the following general formula (1), for example.
_{- (CH 2 -CH (OR 1} )) - (1)
In the general formula (1), R ₁ represents an aliphatic hydrocarbon such as an alkyl group, an alkenyl group, a cycloalkyl group, or a cycloalkenyl group, a phenyl group, a pyridyl group, a benzyl group, a toluyl group, a xylyl group, An aromatic hydrocarbon group in which a carbon atom may be substituted with a nitrogen atom, such as an alkylphenyl group, a phenylalkylene group, a biphenyl group, and a phenylpyridyl group. Moreover, the hydrogen atom on the aromatic ring may be substituted with a hydrocarbon group.

The number of carbon atoms in the R ₁ 1 to 18 are preferred. Any of the above repeating units having an R ₁ group constitutes a hydrophobic block. R ₁ may be a group represented by — (CH (R ₂ ) —CH (R ₃ ) —O) _p —R ₄ or — (CH ₂ ) _m — (O) _n —R ₄ . In this case, R ₂ and R ₃ each independently represents a hydrogen atom or a methyl group. R ₄ represents hydrogen, an alkyl group, an alkenyl group, a cycloalkyl group, or an aliphatic hydrocarbon such as a cycloalkenyl group, a phenyl group, a pyridyl group, a benzyl group, a toluyl group, a xylyl group, an alkylphenyl group, a phenylalkylene group. An aromatic hydrocarbon group in which the carbon atom may be substituted with a nitrogen atom, such as a biphenyl group or a phenylpyridyl group (the hydrogen atom on the aromatic ring may be substituted with a hydrocarbon group, etc.) Represents.

The number of carbon atoms of R ₄ is preferably 1-18, p is preferably 1-18, m is preferably 1-36, and n is preferably 0 or 1. These can be either a hydrophilic block or a hydrophobic block depending on the number of carbon atoms of R ₄ and the values of m and n.

R ₄ represents —Si (CH ₃ ) ₃ , —CHO, —COOR ₅ , —CH ₂ CHO, —CO—CH═CH ₂ , —CO—C (CH ₃ ) ═CH ₂ , —CH ₂ —. _{CH = CH 2, -CH 2 -C} (CH 3) = CH 2, or the like may be -CH ₂ -COOR _5. A hydrogen atom in these groups may be substituted with a halogen atom such as fluorine, chlorine, bromine or the like as long as it is chemically possible. The number of carbon atoms of R ₄ is 1 to 18 is preferred. R ₅ is hydrogen or an alkyl group. These generally constitute a hydrophobic block, but can be hydrophilized by post-treatment. Post-treatment methods include hydrolysis of the trimethylsilyl group, oxidation or reduction of the aldehyde group, hydrolysis of the ester group, neutralization of the carboxylic acid, addition of water to the unsaturated bond, and the like.

In the above R ₁ and R ₅ , the alkyl group or alkenyl group is, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl. , Tetradecyl, hexadecyl, octadecyl, oleyl and the like, and examples of the cycloalkyl group or cycloalkenyl group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, cyclohexenyl and the like.

  Below, the monomer (Ia-Io) which comprises the repeating unit represented by General formula (1) demonstrated above, and the block copolymer (II-a-II-) comprised from these monomers are shown. e) The structure before post-treatment (hydrophilization treatment) is exemplified, but the vinyl ether monomer and block copolymer used in the present invention are not limited to these.

  Furthermore, it is preferable that the number of repeating units of polyvinyl ether [in the above (II-a) to (II-e), m, n, l (el)] is independently 1 to 10,000. Further, the total [in the above (II-a) to (II-e), m + n + 1] is more preferably 10 to 20,000. The number average molecular weight is preferably 500 to 20,000,000, more preferably 1,000 to 5,000,000, and most preferably 2,000 to 2,000,000. These block copolymers may be those obtained by grafting them to other polymers, or those copolymerized with other repeating unit structures. Each block also includes a copolymer of a vinyl ether monomer and other monomers.

  A method for synthesizing a copolymer having a vinyl ether polymer block is not particularly limited, and cation living polymerization (Japanese Patent Laid-Open Nos. 11-322942 and 11-322866) by Aoshima et al. Is preferably used. By using the cationic living polymerization method, we can synthesize various polymers such as homopolymers with exactly the same length (molecular weight), copolymers composed of two or more monomers, and block polymers, graft polymers, gradation polymers, etc. be able to. Moreover, a polyvinyl ether block copolymer can introduce | transduce various functional groups into the side chain.

  The amount of these block copolymers in the present invention is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, based on the mass of the fine particles. If the amount of the block copolymer is less than 10% by mass, the coating of the fine particles becomes insufficient and the dispersion stability is lowered. Is not sufficiently expressed.

  As the hydrophilic fine particles used in the present invention, fine metal particles and fine metal compound particles such as oxides, nitrides, chlorides, sulfates and carbonates can be applied. Examples of the metal fine particles include fine particles of iron, nickel, aluminum, copper, gold, platinum, zinc, and alloys thereof, and examples of the metal compound fine particles include silica, alumina, titanium oxide, zinc oxide, zirconium oxide, and oxide. Examples thereof include fine particles of iron, nickel oxide, copper oxide, barium sulfate, calcium carbonate, but are not limited thereto.

  The shape of these fine particles is not particularly limited. The size of the fine particles is preferably 1 μm or less, more preferably 0.2 μm or less, and further preferably 0.1 μm or less from the viewpoint of dispersion stability and function expression as the fine particles. The proportion of these fine particles in the total mass of the dispersion composition may be appropriately selected according to the use, but is preferably 0.1 to 30% by mass, and more preferably 1 to 20% by mass. If the amount of the particles is less than 0.1% by mass, it is insufficient for function expression. If the amount of the particles exceeds 30% by mass, the aggregation of fine particles and the operability decrease due to the increase in viscosity tend to occur.

  The main liquid medium of the fine particle dispersion composition of the present invention is water, but may contain other water-soluble organic substances. These organic substances have the effect of preventing solidification at the vessel wall when storing the dispersion composition, and preventing freezing at low temperatures. Ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol Diols such as dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, thiodiglycol, neopentyl glycol, 1,4-cyclohexanediol, and polyethylene glycol Class: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monoallyl ether, diethylene glycol monomethyl ether, diethylene glycol Alkylene glycol monoalkyl ethers such as coal monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether; glycerin, 1,2,4-butane Polyols such as triol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, trimethylolethane, trimethylolpropane and pentaerythritol are preferably used. In addition to the above components, various additives such as a surfactant, a pH adjuster, an antioxidant, and an antifungal agent may be added to the fine particle dispersion composition of the present invention.

The fine particle dispersion composition of the present invention can be produced, for example, as follows.
Inorganic fine particles, a block copolymer having a hydrophilic segment and a hydrophobic segment are added to a non-aqueous medium, and subjected to a dispersion treatment using a dispersing machine such as an ultrasonic wave application or a bead mill or a ball mill. The hydrophobic segment of the block copolymer is hydrophilized by post-treatment, an aqueous medium is added, and then the initial non-aqueous medium is distilled off. It can also be produced by kneading the fine particles and the block copolymer together with a small amount of a non-aqueous solvent, hydrophilizing the block copolymer by post-treatment, diluting with a water-based medium, and then distilling off the non-aqueous solvent.

  The fine particle dispersion composition of the present invention is applicable to various uses. For example, if magnetic iron oxide or the like is used as the fine particles, a magnetic paint for a magnetic recording medium can be produced, and if ultrafine titanium oxide is used, an ultraviolet absorbing paint can be produced. Further, by using an inorganic pigment such as iron oxide, nickel oxide, or zinc oxide, an inorganic colored paint can be produced.

One of the most suitable usage forms of the fine particle dispersion composition of the present invention is an ink for an ink jet printer which records by jetting energy to the ink, and in particular, triiron tetroxide (Fe ₃ O ₄ ) or It is suitable for black pigment ink in which titanium black is dispersed. As energy, thermal energy or mechanical energy can be used, but a method using thermal energy is particularly preferable.

  As a printer for inkjet recording, it can be applied to a printer for general households mainly using A4 size paper, a printer for printing business cards and cards, or a large printer for business use. It is suitably used for large machines that require a large amount of ink.

  As a recording medium to be recorded with the ink of the present invention, plain paper without a special coating, so-called inkjet exclusive paper coated with a layer for receiving ink on at least one surface, postcards, business card paper, label paper, cardboard Examples include paper and inkjet films. Ink for an inkjet printer is prepared by diluting the fine particle dispersion composition of the present invention to an appropriate concentration with water, a predetermined water-soluble organic substance, and other surfactants, pH adjusters, antioxidants, antifungal agents as necessary. It can manufacture by adding various additives, such as.

  The proportion of fine particles in the ink for an ink jet printer is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass. If the amount of the particles is less than 0.1% by mass, a sufficient density cannot be obtained in the printed image. If the amount of the particles exceeds 20% by mass, the image density does not increase greatly, but the nozzles are clogged. It causes a drop in discharge stability.

  The water-soluble organic substance added to the ink serves to prevent the ink from solidifying due to drying at the nozzle portion of the ink jet printer. Specifically, alcohols such as isopropanol and butanol; ethylene glycol, diethylene glycol, triethylene Glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, thiodiglycol, neopentyl glycol, 1,4- Diols such as cyclohexanediol and polyethylene glycol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol Alkylene glycol monoalkyl ethers such as dimonoallyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether; glycerin Polyols such as 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, trimethylolethane, trimethylolpropane, pentaerythritol; cyclic ethers such as tetrahydrofuran and dioxane Dimethyl sulfoxide, diacetone alcohol, glycerol monoallyl Ether, N-methyl-2-pyrrolidone, 2-pyrrolidone, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, sulfolane, urea, β-dihydroxyethylurea, acetonylacetone, dimethylformamide, dimethylacetamide, Examples include phenoxyethanol.

  Such a substance may be solid or liquid as long as it is water-soluble. Further, since it is required to remain in the ink even under conditions where water evaporates, the boiling point is preferably higher than that of water, and preferably 120 ° C. or higher. Since it has an effect, it is harder to evaporate than a single substance, so that it is not necessarily limited to a high boiling point substance. These organic substances may be used alone or in combination of two or more. The proportion of these organic substances in the ink is 5 to 50% by mass, preferably 10 to 30% by mass, based on the total mass of the ink.

  Specific examples of the present invention will be described below. However, the present invention is not limited by these examples. In the following description, all “parts” are based on mass.

(1) Synthesis of AB Diblock Copolymer (P-1) After replacing the inside of a glass container equipped with a three-way cock with nitrogen, the adsorbed water was removed by heating at 250 ° C. in a nitrogen gas atmosphere. After returning the system to room temperature, 12 mmol of 2-methoxyethyl vinyl ether, 16 mmol of ethyl acetate, 0.1 mmol of 1-isobutoxyethyl acetate, and 11 mL of toluene were added. Polymerization was started by adding 0.2 mmol of aluminum sesquichloride, and the A component of the diblock copolymer was synthesized.

  4- [2-vinyloxyethoxy] benzoic acid which is B component after the molecular weight is monitored using gel permeation chromatography (GPC, HLC-8220 manufactured by Tosoh Corporation) in a time-sharing manner and polymerization of A component is completed. B component was synthesized by adding 10 mmol of ethyl. The polymerization reaction was stopped by adding a 0.3% by mass ammonia / methanol solution. For the identification of the obtained diblock copolymer, a nuclear magnetic resonance absorption measuring device (NMR, DPX400 manufactured by Bruker BioSpin) and GPC were used, and both obtained results indicating that the target substance was synthesized. It was. The number average molecular weight (Mn) of the obtained diblock copolymer is 32,000 in terms of standard polystyrene, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) indicating the degree of molecular weight distribution. Was 1.2.

(2) Synthesis of AB Diblock Copolymer (P-2) After the inside of the glass container equipped with the three-way cock was replaced with nitrogen, the adsorbed water was removed by heating at 250 ° C. in a nitrogen gas atmosphere. After returning the system to room temperature, 12 mmol of 2-methoxyethyl vinyl ether, 16 mmol of ethyl acetate, 0.1 mmol of 1-isobutoxyethyl acetate, and 11 mL of toluene were added. Polymerization was started by adding 0.2 mmol of aluminum sesquichloride, and the A component of the diblock copolymer was synthesized.

  The molecular weight was monitored in a time-sharing manner using gel permeation chromatography (GPC, HLC-8220 manufactured by Tosoh Corporation), and after the polymerization of component A was completed, the hydroxyl group of 2-hydroxyethyl vinyl ether as component B was replaced with trimethylchlorosilane. B component was synthesized by adding 10 mmol of silylated vinyl monomer. The polymerization reaction was stopped by adding a 0.3% by mass ammonia / methanol solution. For the identification of the obtained diblock copolymer, a nuclear magnetic resonance absorption measuring device (NMR, DPX400 manufactured by Bruker BioSpin) and GPC were used, and both obtained results indicating that the target substance was synthesized. It was. The number average molecular weight (Mn) of the obtained diblock copolymer is 25,000 in terms of standard polystyrene, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) indicating the degree of molecular weight distribution. Was 1.2.

(3) Synthesis of ACB triblock copolymer (P-3):
After replacing the inside of the glass container fitted with the three-way cock with nitrogen, the adsorbed water was removed by heating at 250 ° C. in a nitrogen gas atmosphere. After returning the system to room temperature, 10 mmol of 2-methoxyethoxyethyl vinyl ether, 16 mmol of ethyl acetate, 0.1 mmol of 1-isobutoxyethyl acetate, and 11 ml of toluene were added. Polymerization was started by adding 0.2 mmol of ethylaluminum sesquichloride, and the A component of the triblock copolymer was synthesized.

  The molecular weight was monitored in a time-sharing manner using gel permeation chromatography (GPC, HLC-8220 manufactured by Tosoh Corporation). After the polymerization of component A was completed, synthesis was performed by adding 12 mmol of isobutyl vinyl ether as component C. In the same manner as above, monitoring was performed using GPC to confirm completion of polymerization of the C component. Next, synthesis was carried out by adding 10 mmol of ethyl 4- [2-vinyloxyethoxy] benzoate as component B, and the polymerization reaction was stopped by adding a 0.3 mass% ammonia / methanol solution in the system. It was.

  For the identification of the obtained triblock copolymer, a nuclear magnetic resonance absorption measuring apparatus (NMR, DPX400 manufactured by Bruker BioSpin) and GPC were used, and both obtained results indicating that the target substance was synthesized. It was. The number average molecular weight (Mn) of the obtained triblock copolymer is 45,000 in terms of standard polystyrene, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) indicating the degree of molecular weight distribution. Was 1.3.

Example 1
One part of triiron tetroxide particles (average particle diameter 100 nm) and 1 part of diblock copolymer (P-1) were put into 18 parts of N, N-dimethylformamide and dispersed by applying ultrasonic waves. Thereafter, a mixture of 15 parts of 1N aqueous sodium hydroxide and 10 parts of methanol was added to hydrolyze the ester part of P-1, and excess sodium was removed by dialysis. N, N-dimethylformamide and methanol were distilled off by a rotary evaporator, and water was further added to obtain a fine particle dispersion composition having a solid content of 10% by mass.

Example 2
A fine particle dispersion composition was obtained in the same manner as in Example 1 except that titanium black (average particle diameter: 80 nm) was used instead of the triiron tetraoxide particles.

Example 3
One part of triiron tetroxide particles (average particle size 100 nm) and 1 part of diblock copolymer (P-2) were put into 18 parts of N, N-dimethylformamide and dispersed by applying ultrasonic waves. Thereafter, 15 parts of a 0.1N aqueous sodium hydroxide solution was added to hydrolyze the trimethylsilyl group of P-2, and sodium was removed by dialysis. N, N-dimethylformamide was distilled off by a rotary evaporator, and water was further added to obtain a fine particle dispersion composition having a solid content of 10% by mass.

Example 4
10 parts of triiron tetroxide particles (average particle diameter 100 nm) and 10 parts of diblock copolymer (P-1) were mixed with 1 part of N, N-dimethylformamide and kneaded for 2 hours using a kneader kneader. The resulting mixture was mixed with a ball mill for 24 hours while adding a mixture of 150 parts of 1N sodium hydroxide and 100 parts of methanol in 5 portions to hydrolyze the ester portion of P-1. After removing excess sodium by dialysis, N, N-dimethylformamide and methanol were distilled off by a rotary evaporator, and water was further added to obtain a fine particle dispersion composition having a solid content of 10% by mass.

Example 5
10 parts of triiron tetroxide particles (average particle diameter 100 nm) and 10 parts of triblock copolymer (P-3) were mixed with 1 part of N, N-dimethylformamide and kneaded for 2 hours using a kneader kneader. A mixture of 150 parts of 1N aqueous sodium hydroxide and 100 parts of methanol was added to the resulting mixture in 5 portions, and the mixture was mixed for 24 hours with a ball mill to hydrolyze the ester portion of P-3. After removing excess sodium by dialysis, N, N-dimethylformamide and methanol were distilled off by a rotary evaporator, and water was further added to obtain a fine particle dispersion composition having a solid content of 10% by mass.

Example 6
An ink was prepared by adding 2 parts of glycerin, 2 parts of diethylene glycol and 1 part of isopropanol to 10 parts of the fine particle dispersion composition of Example 1.

Example 7
An ink was prepared by adding 2 parts of glycerin, 2 parts of diethylene glycol and 1 part of isopropanol to 10 parts of the fine particle dispersion composition of Example 5.

Comparative Example 1
1 part of triiron tetroxide particles (average particle diameter 100 nm) and 1 part of polyacrylic acid-maleic acid copolymer (number average molecular weight 15,000) are put into 18 parts of water, and ultrasonic waves are applied and dispersed. A fine particle dispersion composition having a solid content of 10% by mass was obtained.

Comparative Example 2
A fine particle dispersion composition was obtained in the same manner as in Comparative Example 1 using titanium black (average particle diameter of 80 nm) instead of the triiron tetraoxide particles.

Comparative Example 3
Ink was prepared by adding 2 parts of glycerin, 2 parts of diethylene glycol, and 1 part of isopropanol to 10 parts of the fine particle dispersion composition of Comparative Example 1.

(Evaluation)
Dispersion stability:
For the fine particle dispersion compositions of Examples 1 to 5 and Comparative Examples 1 and 2, the average particle size (A) immediately after the adjustment and the average particle size (B) after storage for 1 week at 60 ° C. are manufactured by Otsuka Electronics Co., Ltd. The measurement was performed using a PAR-III dynamic light scattering measurement apparatus. The results are shown in Table 1.

Ink discharge performance for inkjet printers:
The water-based inks of Examples 6 and 7 and Comparative Example 3 were respectively mounted on an ink jet recording apparatus BJF-660 (manufactured by Canon) that ejects ink by applying thermal energy, and printed on glossy paper SP101 (manufactured by Canon). Was done. Next, each ink was held for one week while being mounted on the ink jet recording apparatus, and a printing test was similarly performed for comparison. The results are shown in Table 2.

* 1: Discharge characteristics After printing a 100% solid image at room temperature and resting for 1 minute, an image printed with a 100% solid image again was evaluated according to the following evaluation criteria.
(Double-circle): There was no white stripe and it printed normally.
○: Slight white streaks were observed.
Δ: White streaks were observed throughout the image.
X: The image was hardly printed.

* 2: Color tone A 100% solid image was printed at room temperature, and the sharpness of the color was visually evaluated in four stages. A: Color tone is ideal.
○: Almost satisfactory, but slightly dull in the color when observed in detail.
(Triangle | delta): There exists a dullness of the color which can be recognized easily.
X: Completely turbid color tone.

  As described above, according to the present invention, it is possible to provide a fine particle dispersion composition in which inorganic particles having high weather resistance are stably dispersed in an aqueous medium, and an ink for an ink jet printer.

Claims (5)

A method for producing an aqueous fine particle dispersion composition in which inorganic fine particles having a hydrophilic surface are coated with a block copolymer and dispersed in an aqueous medium ,
The block copolymer is a block copolymer having a polyvinyl ether structure having at least a hydrophilic block composed of a vinyl ether monomer and a hydrophobic block composed of a hydrophilizable vinyl ether monomer ,
1) Coating the inorganic fine particles with the block copolymer by dispersing the block copolymer and the inorganic fine particles in a non-aqueous medium,
2) An aqueous fine particle dispersion composition comprising: an aqueous medium mainly comprising water is added after the hydrophobic block of the block copolymer coated with the inorganic fine particles is hydrophilized . Manufacturing method . The hydrophilization treatment is hydrolysis of a trimethylsilyl group in the hydrophobic block, oxidation or reduction of an aldehyde group, hydrolysis of an ester bond, neutralization of a carboxylic acid, or addition of water to an unsaturated bond. A method for producing the aqueous fine particle dispersion composition described in 1. 2. The hydrophilizable vinyl ether monomer constituting the hydrophobic block is a vinyl monomer obtained by silylating a hydroxyl group of ethyl 4- [2-vinyloxyethoxy] benzoate or 2-hydroxyethyl vinyl ether with trimethylchlorosilane. A method for producing the aqueous fine particle dispersion composition described in 1. The method for producing an aqueous fine particle dispersion composition according to claim 1, wherein the vinyl ether monomer constituting the hydrophilic block is 2-methoxyethyl vinyl ether or 2-methoxyethoxyethyl vinyl ether. The method for producing an aqueous fine particle dispersion composition according to claim 1, wherein the non-aqueous medium is N, N-dimethylformamide.