JPH09249769A - Organic resin microparticle and ink composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink composition made markedly proof against the decomposition of the constituent dye by using organic resin microparticles comprising a surfactant and a polymer dispersant and having a specified particle size. SOLUTION: This microparticle comprises a surfactant and a polymer dispersant and has a mean particle diameter of 20-300nm. The surfactant is desirably a betaine compound (e.g. a compound represented by the formula). The monomer which constitutes the microparticles may be at least one monomer having one radicalpolymerizable unsaturation or a combination thereof with a crosslinking monomer. The polymer dispersant is desirably a polyoxyethylene compound. At least one type of the particles is mixed with a dye, a binder and a water-based solvent to form an ink composition. This composition shows excellent dispersion stability and is made markedly proof against the decomposition of the dye.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to organic resin fine particles and an ink composition thereof, and more particularly to an ink composition in which deterioration of a dye is remarkably suppressed by using organic resin fine particles having excellent dispersion stability.

[0002]

2. Description of the Related Art Organic resin fine particles have been attracting attention in the field of inks and paints as cosmetic additives, plastic modifiers, viscosity modifiers and the like. Among them, it has been proposed to use organic resin fine particles in an ink for an ink jet printer to impregnate and adsorb a dye on the surface of the organic resin fine particles (Japanese Patent Publication No. 60-42833).

Conventionally, organic resin fine particles have been modified with a group having an electric charge on the surface in order to improve dispersion stability. For example, sulfonate groups such as -SO3Na are known (Japanese Patent Laid-Open No. 61-268775). However, there is a problem that the dye is decomposed in the ink or paint in which the dye is added. It was found that the sulfonic acid group is a strongly acidic polar group, so that the dye is decomposed, and particularly the ionic dye is decomposed remarkably. It has also been reported that ammonium base is used on the surface of the organic resin fine particles and the decomposition of the dye is significantly suppressed when the surface of the organic resin fine particles is a weak base of ammonium base (C.Wu: Macromolecules, 27, 7099). (1994)). However, the counter ion of the ammonium base, which is a weak base, is usually a halogen ion typified by a chlorine ion, and this halogen ion corrodes a metal, which poses a practical problem.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic resin fine particle and an ink composition thereof, which is provided with an ink composition in which decomposition of a dye is remarkably suppressed by using the organic resin fine particle having excellent dispersion stability. It was made for the purpose of doing.

[0005]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have found that an organic resin fine particle containing a surfactant and a polymer dispersant and having an average particle size of 20 to 300 nm and a betaine compound is I found that it fits my purpose.

The betaine compound has a characteristic that it exhibits ionicity because it has an ammonium base having a positive charge and a carboxyl group having a negative charge in the molecule and does not require a counter ion. When the betaine compound is present on the surface of the fine particles, the charge balance is neutral and the electric repulsive force is small, but since it is an ionic group, the fine particle surface becomes more hydrophilic and does not release the ionic group. Since the surfaces of the fine particles are neutral, they are stably dispersed in the aqueous solution. Further, the polymer dispersant is mainly a water-soluble polymer compound and has a high affinity for water. When this is added to the fine particle dispersion solution, the polymer dispersant is adsorbed on the fine particles and inhibits the aggregation of the fine particles, so that the fine particles are less likely to settle.

When an ink is produced by using the organic resin fine particles, excellent dispersion stability is exhibited, and decomposition of the dye is significantly suppressed. This is because the pH of the betaine compound on the surface is near neutral to weakly alkaline, so that the effect becomes remarkable especially when the betaine compound is used as the surfactant. Further, the ink using the organic resin fine particles has less bleeding and improves the bleeding property as compared with the ink not containing the same.

Further, the organic resin fine particles obtained by adding the pigment at the time of producing the organic fine particles are adsorbed to the pigment and the pigment is stably dispersed, and the dispersion stability is improved.

The monomer composition of the copolymer constituting the organic resin fine particles of the present invention is (A) a monomer having one radically polymerizable unsaturated group, alone or as a mixture of two or more kinds, or ( B) Two or more radically polymerizable unsaturated groups may be used, or a combination of two kinds of crosslinking monomers may be used in order to increase shape stability. In that case, the weight ratio of (A) and (B) is
95/5 to 99/1 is preferable. When the weight ratio of (A) and (B) is 99/5 or more, the shape stability of the organic resin fine particles is increased, and when it is 99/1 or less, gelation becomes difficult during polymerization, and the desired particle size is easily adjusted. It is possible to obtain fine particles having.

Examples of the monomer having at least one radically polymerizable unsaturated group include the following.

[1] Alkyl (meth) acrylate,
For example, methyl (meth) acrylate, ethyl (meth)
Acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. [2] Polymerizable aromatic compound such as styrene, α-methylstyrene, t-butylstyrene, 4-vinylpyridine, etc.
[3] Carboxyl group-containing monomer such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, etc. [4] Hydroxyl group-containing monomer such as 2-hydroxyethyl (meth) acrylate, Hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, allyl alcohol,
[5] Nitrogen-containing alkyl (meth) acrylates such as methallyl alcohol, eg dimethylaminoethyl (meth) acrylate, [6] Polymerizable amides such as acrylic acid amide, methacrylic acid amide, etc.
[7] Polymerizable nitriles such as acrylonitrile and methacrylonitrile, [8] Polymerizable glycidyl compounds such as glycidyl (meth) acrylate

[9] α-olefins such as ethylene and propylene, [10] vinyl compounds such as vinyl acetate and vinyl propionate, [11] diene compounds such as butadiene and isoprene, and these monomers alone or in combination. Can be used.

Further, examples of the monomer having two or more radically polymerizable unsaturated groups in the molecule include the following.

Ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate,
Tetraethylene glycol di (meth) acrylate,
1,3-butylene glycol di (meth) acrylate,
Trimethylolpropane tri (meth) acrylate,
1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol Di (meth) acrylate, Glycerol Aryloxydi (meth)
Acrylate, 1,1,1-trishydroxymethylethane di (meth) acrylate, 1,1,1-trishydroxymethylethane tri (meth) acrylate, 1,
1,1-trishydroxymethylpropane di (meth) acrylate 1,1,1-trishydroxymethylpropane tri (meth) acrylate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl terephthalate, diallyl Examples include phthalate, allyl (meth) acrylate, and divinylbenzene.

The organic resin fine particles are prepared by using an aqueous solution in which the betaine group-containing compound is dissolved during emulsion polymerization. As a result, the betaine compound having the structural formula shown in Chemical formula 2 is incorporated into the surface of the organic resin and the particles by physical adsorption.

[0015]

Embedded image

The betaine compound used as the surfactant may be any one as long as it contains the betaine compound of Chemical formula 2, and examples thereof include those shown in Chemical formula 1. The amount used is 0.1 to 10 parts by weight, preferably 0.3 to 5 parts by weight, based on 10 parts by weight of the monomer. When it is 0.3 part by weight or more, dispersion stability is improved, and when it is 5 parts by weight or less, an appropriate viscosity is obtained for use of the ink.

From the viewpoint of dispersion stability, the organic resin fine particles preferably have an average particle size of 20 nm to 300 nm.
When the average particle size is 20 nm or more, the dispersion stability increases. On the other hand, if the average particle diameter of the organic resin fine particles is 300 nm or less, the synthesis can be easily performed. The organic resin fine particle solution produced in this manner can be used for various purposes as it is, including the medium, but the mixed solvent is removed by means such as solvent substitution, azeotropic distillation, centrifugation, filtration and drying. You may use it.

An ink composition is prepared by adding an organic dye, a binder and water to the above organic resin fine particles. The ink composition thus obtained exhibits excellent dispersion stability,
Remarkably suppresses decomposition of dye.

As the organic dye, any structure having an organic dye can be used. For example, an acid dye, a direct dye, a cationic dye, a mordant dye, an acid mordant dye, a sulfur dye, a sulfur vat dye, a vat dye. Dyes, soluble vat dyes, azoic dyes, disperse dyes, reactive dyes, oxidation dyes, dyes for synthetic fibers, optical brighteners and the like are preferably used. Also,
You may use these organic dyes individually or in mixture of 2 or more types. In particular, if the organic dye is oil-soluble, the organic dye settles in the case of a solvent containing water as the main component,
When the above-mentioned organic resin fine particles are added at the time of ink preparation, the organic dye is taken in and a stable ink can be prepared. Also in this case, it is possible to use it together with other dyes.

Any binder may be used as long as it is a water-soluble resin, for example, polyacrylic ester resin, polymethacrylic ester resin, polyvinyl chloride resin, benzoguanamine resin, alkyd resin, urea resin, vinyl chloride-vinyl acetate. Examples thereof include copolymers, aromatic sulfonamide resins and styrene resins. You may use resin individually or in mixture of 2 or more types.

The ink composition of the present invention can also be used for ink jet printer inks, general printing inks and paints, and special applications such as for making color filters for liquid crystal displays. .

In the ink composition of the present invention, necessary additives may be added depending on the application. For example, when used as an ink for inkjet printers, it is used for inkjet printers such as anti-clogging agents for print heads, defoaming agents for ink, desiccants, bactericides, humectants, pH adjusters, and water resistance imparting agents Various additives conventionally used in inks can be used in combination.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

(Production of Organic Resin Fine Particles) Example 1 A 2 l three-necked flask was equipped with a cooling tube, a stirrer and a dropping funnel and set in an oil bath, and deionized water 200 was added.
g and heated to 70 ° C. Meanwhile, deionized water 200g
An aqueous solution containing 3 g of azobisisobutyronitrile dissolved therein was added dropwise over 2 hours. In addition, 11.4 g of a 30% solution of dodecyldimethyl betaine and 80 g of polyoxyethylene / polyoxypropylene block polymer (manufactured by Sanyo Kasei: trade name Newpol PE-68) were added to deionized water 40
A monomer composition consisting of 270 g of methyl methacrylate and 11 g of ethylene glycol dimethacrylate was added to a solution dissolved in 0 g to prepare an emulsion solution. This was added dropwise over 2 hours, and the polymerization was completed at the 5th hour. The particle size of the obtained polymer was 68 nm, and the liquid property of the dispersion solution of fine particles was neutral.

Example 2 Synthesis was carried out in the same manner as in Example 1 except that 11.4 g of the 30% solution of dodecyldimethyl betaine was changed to 11.4 g of the 30% solution of stearyl betaine. The particle size of the obtained polymer was 60 nm, and the liquid property of the fine particle dispersion solution was neutral.

Example 3 Synthesis was carried out in the same manner as in Example 1 except that 11.4 g of the 30% solution of dodecyldimethyl betaine was changed to 11.4 g of the 30% solution of octyl betaine. The particle size of the obtained polymer is
It was 85 nm, and the liquid property of the dispersion solution of fine particles was neutral.

Comparative Example 1 Synthesis was performed in the same manner as in Example 1 except that sodium dodecyl sulfate was used instead of dodecyl dimethyl betaine. The particle size of the obtained polymer was 45 nm, and the liquid property of the fine particle dispersion solution was acidic.

(Preparation of Ink) Example 4 0.2 parts by weight of Rhodamine B Extra was added to 100 parts by weight of the organic resin fine particle solution of Example 1, and the mixture was stirred and mixed to obtain a fluorescent pigment ink. Further, this ink was printed by an inkjet printer to obtain a printed matter.

Example 5 To 100 parts by weight of the organic resin fine particle solution of Example 2, 0.2 parts by weight of Rhodamine B extra was added, stirred and mixed to obtain a fluorescent pigment ink. Further, this ink was printed by an inkjet printer to obtain a printed matter.

Example 6 Kayacryl was added to 100 parts by weight of the organic resin fine particle solution of Example 1.
Blue N2G 0.2 part by weight was added, and the mixture was stirred and mixed to obtain a blue pigment ink. Further, this ink was printed by an inkjet printer to obtain a printed matter.

Example 7 Kayacryl was added to 100 parts by weight of the organic resin fine particle solution of Example 2.
Blue N2G 0.2 part by weight was added, and the mixture was stirred and mixed to obtain a blue pigment ink. Further, this ink was printed by an inkjet printer to obtain a printed matter.

Example 8 Kayacryl was added to 100 parts by weight of the organic resin fine particle solution of Example 3.
Blue N2G 0.2 part by weight was added, and the mixture was stirred and mixed to obtain a blue pigment ink. Further, this ink was printed by an inkjet printer to obtain a printed matter.

Comparative Example 2 100 parts by weight of the organic resin fine particle solution of Comparative Example 1 was added to Kayacryl.
Blue N2G 0.2 part by weight was added, and the mixture was stirred and mixed to obtain a blue pigment ink. Further, this ink was printed by an inkjet printer to obtain a printed matter.

Comparative Example 3 An ink was prepared in the same manner as in Example 1 except that 100 parts by weight of the organic resin fine particle solution was changed to 100 parts by weight of deionized water. Further, this ink was printed by an inkjet printer to obtain a printed matter.

(Storage stability test)
After storing for 100 hours in a constant temperature bath of ° C, the color change of the ink was visually observed. It was evaluated as ○ when there was no change visually, and as × when there was a color change visually compared to the initial stage. The inks produced in Examples 4 to 8 and Comparative Examples 2 and 3 were free from foreign matter, aggregation and precipitation even after the storage stability test.

(Permeation Test) The inks prepared in Examples 4 to 8 and Comparative Examples 2 and 3 were printed on a paper by an ink jet printer, and the printed dot diameter was measured.
Based on Example 4, when the spread was 10% or less, it was evaluated as ◯, and when it was 10% or more, as ×.

(Light resistance test) The inks produced in Examples 4 to 8 and Comparative Examples 2 and 3 were printed on a paper by an ink jet printer, and the printed matter was irradiated with a fade meter for 10 hours, and the discoloration was visually observed. I observed. in this case,
○ When there is almost no discoloration, △ when slightly discolored,
The case of discoloration was evaluated as x.

Table 1 shows the above measurement results.

[0038]

[Table 1]

[0039]

As is apparent from Table 1 above, Example 4
It was found that the ink compositions using the organic resin fine particles of the present invention represented by Nos. 8 to 8 not only have excellent dispersion stability, but also markedly suppress the decomposition of dyes and cause little bleeding of printed matter.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09D 11/00 PTG C09D 11/00 PTG // C08K 5/16 KAX C08K 5/16 KAX

Claims (9)

[Claims] 1. Fine organic resin particles containing a surfactant and a polymer dispersant and having an average particle size of 20 to 300 nm. 2. The organic resin fine particles according to claim 1, wherein the surfactant is a betaine compound. 3. The organic resin fine particles according to claim 1, wherein the organic resin fine particles contain a single monomer having one radical-polymerizable unsaturated group or two or more copolymerizable monomers. 4. The organic resin fine particles according to claim 1, further comprising a monomer of a copolymer having a monomer having one radically polymerizable unsaturated group and a crosslinkable monomer. 5. The organic resin fine particles according to claim 1, wherein an insoluble inorganic substance is added during the synthesis of the organic resin fine particles. 6. The organic resin fine particles according to claim 5, wherein the insoluble inorganic substance is graphite. 7. The organic resin fine particles according to claim 1, wherein the polymer dispersant is a polyoxyethylene compound. 8. The ink composition according to claim 1, comprising at least one kind of the organic resin fine particles, a dye, a binder, and a solvent containing water as a main component. 9. The organic resin fine particles according to claim 1, wherein the betaine compound has a structure shown in Chemical formula 1. Embedded image