JP3990346B2 - Aqueous colorant resin composition, process for producing the same, pigment dispersion, and ink for inkjet printer - Google Patents

Description

  The present invention relates to a colored resin composition and a method for producing the same, and further relates to an aqueous pigment dispersion using the colored resin composition and an ink for an ink jet printer.

  In inks and paints, it has been desired to reduce fading caused by light or an oxidizing gas in coated materials and printed materials. For this reason, there is an increasing demand for inks and paints that use a pigment-based color material in which molecules are gathered, instead of a dye-based color material in which the pigment is present in a molecular state, as a colorant. In these pigment-based inks and paints, it is necessary to stably disperse the pigment in the form of fine particles. In particular, from the viewpoint of safety and environmental considerations, the dispersion stability in a medium mainly composed of water rather than an organic solvent is required. Often required. In particular, in an inkjet printer that has been rapidly spreading in recent years, measures such as stirring the ink before use of the ink cannot be taken, and since it is necessary to discharge the ink from a minute nozzle, the dispersibility of the pigment in the ink can be reduced. The requirements are very strict.

  In order to stably disperse the pigment in the aqueous medium, a so-called self-dispersing pigment in which the pigment surface is modified to make the surface of the originally hydrophobic pigment particles hydrophilic is used. Although this self-dispersing pigment is excellent in dispersion stability, the printed matter formed using the ink has low water resistance, and the ink easily penetrates into a recording medium such as paper, and the color of the formed image. There may be a problem such as insufficient density.

  In order to solve these problems, attempts have been made to coat pigment particles with a resin. For example, in Patent Documents 1 to 4, a block copolymer containing a hydrophobic part that easily adheres to a pigment and a hydrophilic part that has a high affinity for an aqueous medium is attached to the pigment particle surface, Patent Document 5 discloses an example using a graft copolymer having similar properties. According to these methods, it is said that an ink having high dispersion stability and improved water resistance of printed matter can be realized. However, the dispersion stability mentioned here is a period of about several months during which the ink or pigment dispersion is used. If these inks are used immediately after production, there is no problem. For example, assuming that a large number of inks are manufactured and stored and then sequentially provided to the market, sufficient ink storage stability is obtained. Is difficult to achieve.

  On the other hand, in the field of colored resin moldings and the like, it is practiced to manufacture and store a solid colored resin in which a color material is dispersed and mold it as necessary to obtain a product (see Patent Document 6). ). In this case, since the colored resin is stored in a solid state, the dispersion state of the coloring material can be maintained semipermanently for an extremely long time. Although it is conceivable to apply the same method to the field of inks using pigment dispersions or pigments as color materials, the molding resins shown in these examples are not soluble in aqueous media. Therefore, the colored resin cannot be used as it is for an aqueous dispersion or an aqueous ink. On the other hand, Patent Document 7 discloses a colored resin composition using a block copolymer in consideration of application to ink and lacquer. However, the resin used here is a general block copolymer such as acrylic, methacrylic, styrene, maleic acid, and the dispersion stability of the pigment particles when the pigment dispersion or ink is finally obtained. Further improvement is desired with respect to image fastness of printed matter by ink.

JP-A-5-179183 Japanese Patent Laid-Open No. 6-136411 JP 7-53841 A Japanese Patent Laid-Open No. 11-228891 JP-A-9-188732 JP-A-6-88009 JP 2003-49110 A

  In view of the above situation, the present invention can be used for the preparation of pigment dispersions and pigment inks excellent in dispersion stability and image fastness, and can be stored for a long period of time, and a colored resin composition in which pigments are uniformly dispersed. The purpose is to provide.

The above object can be achieved by the present invention described below. That is, the present invention has a pigment, at least a hydrophobic part represented by the following general formula (1), and a part represented by the following general formula (2) having an acidic group that exhibits hydrophilicity by neutralization. The block surface of the pigment is coated with the block copolymer by mixing the block copolymer having a polyvinyl ether structure with a solvent that dissolves the block copolymer, and then distilling the solvent to solidify. A resin composition for an aqueous colorant is provided.
^{_{- (CH 2 -CH (OR 1}} )) - (1)
(In the above general formula (1), R ¹ is an alkyl group having 1 to 18 carbon atoms.)
^{_{- (CH 2 -CH (OR 6}} )) - (2)
(In the above general formula (2), R ⁶ represents — (CH ₂ ) _m — (O) _n —CH ₂ —COOH or — (CH ₂ ) _m — (O) _n —C ₆ H ₄ —COOH. M is 1 to 36, and n is 0 or 1.)

  In the present invention, the block copolymer having a polyvinyl ether structure has a tough and stable main chain skeleton, and by selecting a side chain bonded to the main chain, the block copolymer has a hydrophobic moiety and It can have a hydrophilic part. By using the block copolymer as a pigment dispersion medium, the hydrophobic portion interacts with the pigment, and the pigment can be stably dispersed and retained in the resin for a long period of time.

Moreover, in this invention, it has a part represented by the following general formula (2) which has an acidic group which expresses a hydrophilic property by neutralization and at least the hydrophobic part represented by the following general formula (1) by neutralization. A method for producing a resin composition for an aqueous colorant, comprising: mixing a block copolymer having a polyvinyl ether structure with a solvent in which the block copolymer is dissolved and then distilling off the solvent. provide.
^{_{- (CH 2 -CH (OR 1}} )) - (1)
(In the above general formula (1), R ¹ is an alkyl group having 1 to 18 carbon atoms.)
^{_{- (CH 2 -CH (OR 6}} )) - (2)
(In the above general formula (2), R ⁶ represents — (CH ₂ ) _m — (O) _n —CH ₂ —COOH or — (CH ₂ ) _m — (O) _n —C ₆ H ₄ —COOH. M is 1 to 36, and n is 0 or 1.)
According to the above method, once the pigment and the block copolymer are uniformly mixed in a suitable solvent, the solvent is removed, and the hydrophobic portion in the block copolymer surrounds the pigment particles. A resin composition for an aqueous colorant having a high viscosity can be obtained.

The invention further said aqueous colorant resin composition, a pigment dispersion characterized by comprising dispersed in an alkaline aqueous medium, and ink for ink jet printers comprising a pigment dispersion (hereinafter simply "ink" Provided).
The block copolymer has an acidic group that develops hydrophilicity by neutralization. Therefore, when dispersed in an aqueous medium in the presence of an appropriate neutralizing agent, the hydrophilic portion has an affinity for the aqueous medium. To do. On the other hand, since the hydrophobic part of the block copolymer covers the pigment particle surface, the block copolymer stably disperses in the aqueous medium with the hydrophilic part facing outward while the pigment particle is held inside. To do. In addition, the weather resistance inherent to the pigment is added to the effect of enhancing the weather resistance by being coated with the block copolymer, and at the same time, water resistance is also imparted to the printed matter by the block copolymer having the polyvinyl ether structure of the present invention. Therefore, very high image robustness can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the colored resin composition in which the pigment can disperse | distribute uniformly which can be stored for a long term can be provided. In addition, an aqueous pigment dispersion excellent in pigment dispersion stability and image fastness and ink can be provided by using the colored resin composition.

Next, the present invention will be described in more detail with reference to preferred embodiments.
The block copolymer used in the present invention includes at least one hydrophobic block (A, A ′) and at least one block (B, B ′) having an acidic group that exhibits hydrophilicity by neutralization. Consists of. In addition to this, other types of hydrophilic blocks (C), for example, nonionic hydrophilic blocks may be included.

  The arrangement of each block in the block copolymer is not particularly limited, but from the viewpoint of enhancing the dispersibility of the pigment when the colored resin composition is dispersed in an aqueous medium, an acidic group that exhibits hydrophilicity by neutralization is used. Those having a block at the end of the polymer chain are preferred. Examples include AB type, BAB 'type, AA'B type, ABB' type, ACB type (A and A ', and B and B' may be the same or different). A, A ', B, B', and C are homopolymer or copolymer blocks.

  A preferred block copolymer used in the present invention has a hydrophobic block made of a homopolymer or copolymer of a vinyl ether monomer and an acidic group that develops hydrophilicity by neutralization, made of a homopolymer or copolymer of a vinyl ether monomer. Including at least blocks. It may also contain other types of hydrophilic blocks consisting of homopolymers or copolymers of vinyl ether monomers.

It is preferable that blocks other than the part which has an acidic group in these polymers have a repeating unit shown by 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 phenylalkyl group, a biphenyl group, and a phenylpyridyl group. Moreover, the hydrogen atom on the aromatic ring may be substituted with a hydrocarbon group. R ¹ preferably has 1 to 18 carbon atoms. These structures are generally hydrophobic.

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 represent a hydrogen atom or a methyl group, and R ⁴ represents an aliphatic hydrocarbon such as an alkyl group, an alkenyl group, a cycloalkyl group, or a cycloalkenyl group, a phenyl group, Aromatic hydrocarbon groups in which carbon atoms may be substituted with nitrogen atoms, such as pyridyl group, benzyl group, toluyl group, xylyl group, alkylphenyl group, phenylalkyl group, biphenyl group, phenylpyridyl group (aromatic The hydrogen atom on the ring may be substituted with a hydrocarbon group), —CHO, —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 , —CH ₂ —COOR ^5, etc., and the hydrogen atom in these groups is fluorine, as long as it is chemically possible. chlorine It may be substituted with a halogen atom such as bromine. R ⁴ preferably has 3 to 18 carbon atoms. R ⁵ is an alkyl group. p is preferably 1 to 18, m is preferably 1 to 36, and n is preferably 0 or 1. These structures are generally hydrophilic, but are hydrophobic when R ⁴ is a hydrocarbon having a large number of carbon atoms, when m is large, or when n is 0.

In R ¹ and R ⁴ , examples of the alkyl group or alkenyl group include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl. , Tetradecyl, hexadecyl, octadecyl, oleyl, linoleyl and the like, and examples of the cycloalkyl group or cycloalkenyl group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, cyclohexenyl and the like.

On the other hand, the block having an acidic group preferably has a repeating unit represented by the following general formula (2), for example.
^{_{- (CH 2 -CH (OR 6}} )) - (2)
In the above general formula (2), R ⁶ represents — (CH (R ⁷ ) —CH (R ⁸ ) —O) _p —CH ₂ —COOH, — (CH (R ⁷ ) —CH (R ⁸ ) — _{O) p -C 6 H 4 -COOH} , - (CH 2) m - (O) n -CH 2 -COOH, - (CH 2) m - , etc. _{(O) n -C 6 H 4} -COOH. In this case, R ⁷ and R ⁸ each independently represent a hydrogen atom or a methyl group, and the hydrogen atom in the above formula is substituted with a halogen atom such as fluorine, chlorine, bromine or the like as long as it is chemically possible. It may be. p is preferably 1 to 18, m is preferably 1 to 36, and n is 0 or 1.
Below, the monomer (Ia-Io) which comprises the repeating unit represented by general formula (1) and (2) demonstrated above, and the block copolymer (II-a-II) which consists of this monomer Although the structure of -c) is illustrated, the monomer and block copolymer of the polyvinyl ether structure used for this invention are not limited to these.

  Among these exemplified monomers, (Ia), (Ib), (If), (Ig) and (Ih) are monomers having strong hydrophilicity, and (Id ), (Ie), (Ii), (Ij) and (In) are highly hydrophobic monomers, and (Ik), (Im) and (Io) ) Is a typical monomer having an acidic group.

  In addition, the number of repeating units of each block [in the above (II-a) to (II-c), m, n, l] is preferably independently 1 to 10,000. Further, the total [in the above (II-a) to (II-c), m + n or l + m + n] 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. Further, these block copolymers may be those obtained by grafting them to other polymers, or may be those copolymerized with other repeating units (monomers). Each block also includes a copolymer of a vinyl ether monomer and other monomers.

  The method for synthesizing the copolymer having the vinyl ether polymer block is not particularly limited, and cation living polymerization by Aoshima et al. (Japanese Patent Laid-Open Nos. 11-322942 and 11-322866) 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 of two or more monomers, and block copolymers, graft copolymers, and gradation copolymers. be able to. Moreover, a polyvinyl ether block can introduce | transduce various functional groups as a side chain in the principal chain.

  The proportion of these block copolymers in the colored resin composition of the present invention is preferably 10 to 90 mass%, more preferably 20 to 70 mass%. When the amount of the block copolymer is less than 10% by mass, the dispersion of the pigment in the composition is insufficient, whereas when the amount of the block copolymer exceeds 90% by mass, the resin is insufficiently colored. .

A pigment is preferable as the color material used in the present invention. Specifically, it is as follows, but the present invention is not limited to these.
(Black pigment)
Raven760Ultra, Raven1060Ultra, Raven1080Ultra, Raven1100Ultra, Raven1170, Raven1200, Raven1250, Raven1255, Raven1500, Raven2000, Raven2500Ultra, Raven3500, Raven5250, Raven5750, Raven7000, Raven5000UltraII, Raven1190UltraII (Made by Columbia Carbon L , Rega1400R, Rega1660R, Rega1330R, Monarch800, Monarch880, Monarch900, Monarch1000, Monarch1300, Monarch1400 (above, manufactured by Cabot); Color Black FW1, Color Black FW2, Color Black FW200, Color Black 18, Color Black S160, Color Black S170, Special Black 4, Special Black 4A, Special Black 6, Special Black 550, Printex35, Printex45, Printex55, Printex85, Printex95, PrintexU, Printex140U, PrintexV, Printex140V (above, manufactured by Degussa); 25, no. 33, no. 40, no. 45, no. 47, no. 52, no. 900, no. 970, no. 2200B, no. 2300, no. 2400B, MCF-88, MA600, MA77, MA8, MA100, MA220, MA230 (above, manufactured by Mitsubishi Chemical Corporation);

(Blue pigment)
C. I. Pigment blue-1, C.I. I. Pigment blue-2, C.I. I. Pigment blue-3, C.I. I. Pigment blue-15, C.I. I. Pigment blue-15: 2, C.I. I. Pigment blue-15: 3, C.I. I. Pigment blue-15: 4, C.I. I. Pigment blue-16, C.I. I. Pigment blue-22, C.I. I. Pigment blue-60, etc .;

(Red pigment)
C. I. -Pigment Red-5, C.I. I. -Pigment Red-7, C.I. I. -Pigment Red-12, C.I. I. -Pigment Red-48, C.I. I. -Pigment Red-48: 1, C.I. I. -Pigment Red-57, C.I. I. -Pigment Red-112, C.I. I. -Pigment Red-122, C.I. I. -Pigment Red-123, C.I. I. -Pigment Red-146, C.I. I. -Pigment Red-168, C.I. I. -Pigment Red-184, C.I. I. -Pigment Red -202, C.I. I. -Pigment Red-207 etc .;

(Yellow pigment)
C. I. Pigment yellow-12, C.I. I. Pigment yellow-13, C.I. I. Pigment yellow-14, C.I. I. Pigment yellow-16, C.I. I. Pigment yellow-17, C.I. I. Pigment yellow-74, C.I. I. Pigment yellow-83, C.I. I. Pigment yellow-93, C.I. I. Pigment yellow-95, C.I. I. Pigment yellow-97, C.I. I. Pigment yellow-98, C.I. I. Pigment yellow-114, C.I. I. Pigment yellow-128, C.I. I. Pigment yellow-129, C.I. I. Pigment yellow-151, C.I. I. Pigment yellow-154 and the like.

  In addition, titanium oxide, zinc oxide, iron oxide, zirconium oxide, silica, alumina, silicon nitride, silicon carbide, and other inorganic oxides, nitrides, carbide particles, and composite particles in which these are coated with an organic pigment (for example, Also, Digit Color series manufactured by Toda Kogyo Co., Ltd. can be used in the present invention.

  The colored resin composition of the present invention is preferably produced, for example, as follows. That is, the pigment and block copolymer are introduced into a solvent that can dissolve the block copolymer of the present invention and has high affinity with the pigment, and the pigment is dispersed by ultrasonic irradiation, bead mill, ball mill, roll mill, or the like. . After uniformly dispersing the pigment, the solvent is removed by drying under reduced pressure to obtain a colored resin composition in which the pigment is uniformly dispersed. The amount of solvent used depends on the dispersion method used, but in the case of ultrasonic irradiation or ball mill, a relatively large amount of solvent is added to make the mixture fluid, and in the case of roll mill or kneader, the amount of solvent. Is preferably reduced to a clay-like mixture.

  Since the colored resin composition obtained in this way is a solid that does not substantially contain a solvent, the pigment particles dispersed therein do not aggregate or settle and maintain a good dispersion state semipermanently. Can do. Therefore, a large amount can be manufactured and stored, and a part of the ink can be made into an ink or a paint if necessary.

  A liquid dispersion can be prepared by dispersing the colored resin composition of the present invention in an appropriate aqueous medium. For example, if the colored resin composition of the present invention is put into an alkaline aqueous solution and dispersed by a bead mill, a ball mill, or the like, aqueous pigment dispersions applicable to various applications can be obtained. As the alkali to be used, sodium hydroxide, potassium hydroxide, lithium hydroxide, tetraalkylammonium hydroxide and the like can be used, but sodium hydroxide, potassium hydroxide and lithium hydroxide are preferable. At this time, the hydrophobic block of the block copolymer is firmly attached to the surface of the pigment particles, and the acidic group is ionized by neutralization with alkali to express hydrophilicity. Thus, a pigment dispersion stably dispersed in water is formed. Since the pigment particles are dispersed in a state of being coated with the block copolymer, when coating or printing is performed using this dispersion, the resulting coated or printed material has only the inherent weather resistance of the pigment. In addition, the effect of the coating of the block copolymer is added, and higher weather resistance is imparted.

  If there is no hydrophobic block in the block copolymer, sufficient pigment dispersibility cannot be obtained at the stage of producing the colored resin composition, and the pigment surface cannot be dispersed when dispersed in an aqueous medium. The pigment particles are agglomerated due to stripping. On the other hand, if there is no acidic group that develops hydrophilicity by neutralization in the block copolymer, the block copolymer precipitates or aggregates when the colored resin composition is dispersed in an aqueous medium. . In addition, when a block copolymer having a hydrophilic block from the beginning is used instead of a block that exhibits hydrophilicity by neutralization, the solubility of the resin in the solvent during the process of producing the colored resin composition Insufficient and a uniform pigment dispersion cannot be obtained. Therefore, the block copolymer used in the present invention must have a hydrophobic block and a block having an acidic group that develops hydrophilicity by neutralization. Further, the acidic group in the block copolymer is preferably a carboxyl group, and the abundance of the carboxyl group in the block copolymer is preferably 1 to 200 mg in terms of sodium hydroxide per 1 g of the block copolymer. More preferably, it is 2 to 150 mg. If the abundance of the carboxyl group is less than the above range, there is a possibility that the same inconvenience occurs as in the case where there is no acidic group as described above. On the other hand, if the abundance of the carboxyl group exceeds the above range, the hydrophobicity There is a possibility of causing the same inconvenience as when the block does not exist.

  The aqueous dispersion of the pigment can be used as an ink for an ink jet printer by further adding an appropriate water-soluble organic substance as required. The amount of the pigment in the ink is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass. If the amount of the pigment is less than 0.1% by mass, a sufficient density cannot be obtained in the printed image. If the amount of the pigment exceeds 20% by mass, the image density does not increase greatly, but clogging in the nozzle, etc. Ink ejection stability is reduced.

  The organic substance added to the ink mainly serves to prevent the ink from solidifying due to drying at the nozzle portion of the ink jet printer and stabilize the ejection. 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 Diols such as 1,4-cyclohexanediol and polyethylene glycol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether , Alkylene glycol monoalkyl ethers such as ethylene glycol monoallyl 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 Polyols such as glycerin, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, trimethylolethane, trimethylolpropane, pentaerythritol; tetrahydrofuran, dioxane, etc. Cyclic ethers of dimethyl sulfoxide, diacetone alcohol, Serine monoallyl ether, N-methyl-2-pyrrolidone, 2-pyrrolidone, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, sulfolane, urea, β-dihydroxyethylurea, acetonylacetone, dimethylformamide, Examples thereof include dimethylacetamide and phenoxyethanol.

  Such an organic 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 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.

  In addition to the above components, for example, various additives such as surfactants, pH adjusters, antioxidants, and antifungal agents may be added to the colored resin composition, pigment dispersion, and ink of the present invention. Good.

  The ink of the present invention can be suitably used in an ink jet recording method in which energy is applied to the ink to cause it to fly. 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 for recording with the ink of the present invention, plain paper without special coating, so-called ink jet exclusive paper coated with a layer for receiving ink on at least one side, postcard, business card paper, label paper, cardboard paper And an inkjet film.

  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.

Synthesis of diblock copolymer (Polymer 1):
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, 12 mmol of isobutyl vinyl ether, 16 mmol of ethyl acetate, 0.1 mmol of 1-isobutoxyethyl acetate, and 11 ml of toluene were added, and when the temperature inside the system reached 0 ° C., ethyl aluminum sesquichloride Polymerization was started by adding 0.2 mmol to synthesize a hydrophobic block as the first component of the diblock copolymer.

  2- (Ethoxycarbonyl) which becomes the raw material of the acidic group-containing block after the polymerization of the first component is completed by monitoring the molecular weight in a time-sharing manner using gel permeation chromatography (GPC, HLC-8220 manufactured by Tosoh Corporation). The second component was synthesized by adding 10 mmol of ethyl vinyl ether, and the polymerization reaction was stopped by adding a 0.3 mass% ammonia / methanol solution to the system. 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 weight average molecular weight (Mw) / number average molecular weight ratio (Mw / Mn) indicating the degree of molecular weight distribution is 1.3. Met. The ester part of the second component of this diblock copolymer is hydrolyzed in a mixed solvent of 5 times equivalent amount of sodium hydroxide and methanol and then free of carboxyl groups, and the solvent is distilled off to obtain a carboxyl group-type polymer 1 Got.

Synthesis of triblock copolymer (Polymer 2):
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, 12 mmol of 1-isobutyl 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 sesquichloride, and a hydrophobic block that was the first 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 the first component was completed, 12 mmol of 2-methoxyethyl vinyl ether was added. Polymerization of the hydrophilic block as a component was performed, and monitoring was performed using GPC in the same manner as described above to confirm the completion of polymerization of the second component. Next, 10 mmol of 4- [2-vinyloxyethoxy] benzoate, which is a raw material for the acidic group-containing block, was added to synthesize the third component, and the polymerization reaction was stopped by 0.3% by mass in the system. Performed by adding ammonia / methanol solution.

  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 30,000 in terms of standard polystyrene, and the weight average molecular weight (Mw) / number average molecular weight ratio (Mw / Mn) indicating the degree of molecular weight distribution is 1.3. Met. The ester part of the third component of this triblock copolymer was hydrolyzed in a mixed solvent of 5 times equivalent amount of sodium hydroxide and methanol and then freed from the carboxyl group, the solvent was distilled off, and the carboxyl group type polymer 2 Got.

Determination of the amount of alkali required for neutralization of polymers 1 and 2:
Polymers 1 and 2 are dissolved in tetrahydrofuran at a concentration of 2% by mass and various concentrations of aqueous sodium hydroxide solution are added, and then the solution is dropped on a calcium fluoride single crystal plate and dried. The infrared absorption spectrum was measured with (FT / IR5300 manufactured by JASCO Corporation). In both of the above two types of block copolymers to which alkali has been added, absorption of carboxyl group ions is observed at 1547 cm ⁻¹ , and the absorption intensity increases with the amount of alkali added, but the amount of alkali addition exceeds a certain value. And no more increase. This amount of alkali was used as a carboxyl group equivalent. The obtained equivalent was 55 mg-NaOH for polymer 1 and 60 mg-NaOH for polymer 2 with respect to 1 g of the block copolymer.

[Examples 1 to 9]
Preparation of colored resin composition:
1 part of the above polymer 1 or polymer 2 was added to 18 parts of tetrahydrofuran together with 1 part of the pigment described in Table 1, and mixed and dispersed by a bead mill for 2 hours. This liquid was put into a vacuum container, tetrahydrofuran was distilled off, and it was dried at room temperature in a vacuum drier to obtain colored resin compositions of Examples 1-9. The produced colored resin composition is shown in Table 1.

Preparation of aqueous pigment dispersion:
To 1 part of each colored resin composition, 9 parts of water containing a carboxyl group and an equivalent amount of sodium hydroxide of the block copolymer in each colored resin composition are added and mixed for 5 hours in a bead mill. The corresponding aqueous pigment dispersion was obtained.

Ink preparation:
1 part of diethylene glycol and 1 part of glycerin were added to 8 parts of each of the above pigment aqueous dispersions to obtain a corresponding aqueous ink.

[Comparative Examples 1-5]
Using a styrene-maleic acid copolymer (Polymer 3) having a number average molecular weight of 10,000 as a polymer, a colored resin composition having the composition shown in Table 2 was prepared in the same manner as in the above Example.

  Further, by using the colored resin compositions shown in Table 2, pigment aqueous dispersions and inks corresponding to the same were prepared in the same manner as in the Examples.

[Evaluation]
Storage stability of colored resin composition:
When each of the colored resin compositions of Examples 2 and 6 and Comparative Example 2 was prepared as an aqueous dispersion immediately after the preparation, and after each of the colored resin compositions was stored at 100 ° C. for 4 weeks, it was aqueous. The average particle diameter of the pigment in the dispersion was compared with the case where the dispersion was prepared. A PAR-III dynamic light scattering measuring device manufactured by Otsuka Electronics Co., Ltd. was used for measurement of the average particle size. The results are shown in Table 3.

なお、他の実施例および他の比較例も表３と同様の結果であった。

The results of other examples and other comparative examples were the same as in Table 3.

Dispersion stability of aqueous pigment dispersion:
With respect to the aqueous pigment dispersions of the above Examples and Comparative Examples, the average particle size immediately after preparation and after storage at 60 ° C. for 4 weeks was measured with a PAR-III dynamic light scattering measurement device manufactured by Otsuka Electronics Co., Ltd. The results are shown in Table 4.

Weather resistance:
Each of the inks of the examples and comparative examples is mounted on an ink-jet recording apparatus BJF-660 (manufactured by Canon) having an on-demand type multi-recording head that ejects ink by applying thermal energy corresponding to a recording signal to the ink. did. The water resistance and gas resistance of the glossy paper SP101 made by Canon were evaluated using a recording medium on which a 100% solid image was printed at 5 ° C. in an environment with a relative humidity of 10%.

<Water resistance>
The reflection density (X) of the printed recording medium was measured using an optical reflection densitometer (Macbeth densitometer RD-918). After leaving the printed matter for 12 hours after printing, leave the printed matter in tap water for 5 minutes, measure the reflection density (Y) of the print after drying the water, and before and after the water resistance test. The residual ratio of the reflection density (the following formula) was used as a measure of water resistance. The evaluation criteria were as follows.
Residual rate = [XY] / X × 100%
○: The residual ratio of reflection density is 90% or more.
Δ: The residual ratio of reflection density is 80% or more and less than 90%.
X: The residual ratio of reflection density is less than 80%.
The evaluation results are shown in Table 5.

<Gas resistance>
The reflection density (X) of the printed recording medium was measured using an optical reflection densitometer (Macbeth densitometer RD-918). The printed recording medium is put into an ozone exposure tester (made by Suga Test Instruments Co., Ltd., special order), exposed to ozone at a concentration of 1 ppm for 4 hours under the conditions of 40 ° C. and 55% RH, and the reflection density after exposure (Y ) Was measured and used as a measure of gas resistance as the residual ratio of reflection density before and after the gas resistance test (the following formula). The evaluation criteria were as follows.
Residual rate = [XY] / X × 100%
○: The residual ratio of reflection density is 90% or more.
Δ: The residual ratio of reflection density is 85% or more and less than 90%.
X: The residual ratio of reflection density is less than 85%.
The evaluation results are shown in Table 5.

Ink ejection characteristics:
Each of the inks of the examples and comparative examples is mounted on an inkjet recording apparatus BJF-660 (manufactured by Canon) having an on-demand type multi-recording head that ejects ink by applying thermal energy corresponding to the recording signal to the ink. did. A 100% solid image was printed on Canon glossy paper SP101 in an environment of 5% at 10 ° C. and a relative humidity of 10%. did.
(Double-circle): There is no white stripe and it is printed normally.
○: Slight white streaks are observed at the beginning of printing.
Δ: White streaks are observed in the entire image.
X: An image is hardly printed.
The evaluation results are shown in Table 6.

  ADVANTAGE OF THE INVENTION According to this invention, the colored resin composition in which the pigment can disperse | distribute uniformly which can be stored for a long term can be provided. In addition, an aqueous pigment dispersion excellent in pigment dispersion stability and image fastness and an ink for an ink jet printer can be provided by using the colored resin composition.

Claims (6)

A block of polyvinyl ether structure having a pigment and at least a hydrophobic part represented by the following general formula (1) and a part represented by the following general formula (2) having an acidic group that exhibits hydrophilicity by neutralization aqueous and polymer were mixed in a solvent which dissolves the block copolymer, the pigment surface by solidifying the solvent was distilled off, characterized in that it is coated with the block copolymer Resin composition for colorant.
^{_{- (CH 2 -CH (OR 1}} )) - (1)
(In the above general formula (1), R ¹ is an alkyl group having 1 to 18 carbon atoms.)
^{_{- (CH 2 -CH (OR 6}} )) - (2)
(In the above general formula (2), R ⁶ represents — (CH ₂ ) _m — (O) _n —CH ₂ —COOH or — (CH ₂ ) _m — (O) _n —C ₆ H ₄ —COOH. M is 1 to 36, and n is 0 or 1.) Acid groups of the block copolymer is a carboxyl group, the abundance of the carboxyl group, the block copolymer per 1g, aqueous colorant of claim 1 which is 1~200mg in sodium hydroxide terms use resin composition. A block of polyvinyl ether structure having a pigment and at least a hydrophobic part represented by the following general formula (1) and a part represented by the following general formula (2) having an acidic group that exhibits hydrophilicity by neutralization A method for producing a resin composition for an aqueous colorant, comprising: mixing a polymer in a solvent that dissolves the block copolymer, and then distilling off the solvent.
^{_{- (CH 2 -CH (OR 1}} )) - (1)
(In the above general formula (1), R ¹ is an alkyl group having 1 to 18 carbon atoms.)
^{_{- (CH 2 -CH (OR 6}} )) - (2)
(In the above general formula (2), R ⁶ represents — (CH ₂ ) _m — (O) _n —CH ₂ —COOH or — (CH ₂ ) _m — (O) _n —C ₆ H ₄ —COOH. M is 1 to 36, and n is 0 or 1.) Acid groups of the block copolymer is a carboxyl group, the abundance of the carboxyl group, the block copolymer per 1g, aqueous colorant of claim 3 which is 1~200mg in sodium hydroxide terms For producing a resin composition for use . The claim 1 or 2 aqueous colorant resin composition according to the pigment dispersion characterized by comprising dispersed in an aqueous-alkaline medium.   An ink for an ink jet printer, comprising the pigment dispersion according to claim 5.