JPH08259863A - Ink jet recording ink - Google Patents

Abstract

PURPOSE: To obtain an ink jet recording ink capable of high-grade image recording and printing, and compatible with reliability against high clogging development. CONSTITUTION: This ink is obtained by blending an ink jet recording ink containing a water-soluble dye or finely dispersible pigment with aspherical resin particles 0.05-2.0μm in average diameter in terms of weight (pref. >=1.2 in degree of asphericity, nonswellable at room temperature to lower alcohols and/or alkylene glycols and/or alkanolamines, and consisting mainly of a polyester resin or an ionomer resin constituted of ethylene/(meth)acrylic acid copolymer).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a computer printer, a word processor printer, a facsimile, a digital copying machine, a CAD output plotter, and a pop (POP).
The present invention relates to an ink jet recording ink which has been widely used for printing lighters, large signboards, poster printers and the like, fabrics, carpets, wallpaper and the like.

[0002]

2. Description of the Related Art Ink jet recording technology is non-contact recording and has a wide range of application from small recording equipment to super-large equipment, and since it is relatively easy to colorize it, it has a wide range from OA to industrial use. Used in. Ink jet recording is roughly classified into a continuous jet type and an on-demand jet type according to its form. The former is mainly used for industrial printers, and the latter is mainly used for small OA and portable printers. In particular, the demand for small-sized on-demand printers based on the thermal bubble jet method or the piezo method has been rapidly increasing in recent years. Inks used in industrial printers are mainly solvent-type inks because of the requirement for quick-drying, and water-based inks are mainly used in OA and portable printers in consideration of the use environment.

(Water-soluble dye ink) Most water-based inks are water-soluble dye type inks. Water-soluble dye-type ink is mainly classified into acid dyes, direct dyes, some food dyes, and other aqueous solutions of water-soluble dyes, and glycols, alkanolamines as surface moisturizers, interfaces for preparation of surface tension, etc. It contains a small amount of activator, alcohols and the like. Although there are some patent proposals of adding a water-soluble resin component as a binder component, it seems that it has not been used practically because of concern over nozzle clogging. These water-soluble dye type inks are most commonly used because of their high reliability against nozzle clogging. However, such a water-soluble dye-type ink is liable to bleed on the recording paper because it is an aqueous solution of the dye, and conversely, because it is prepared so as to quickly penetrate into the recording paper due to the need to increase the apparent drying speed, it may cause ink bleeding. It is obliged to lower the recording quality. It is also obvious that the water resistance is poor because it is a water-soluble dye. Furthermore, it is difficult to say that a water-soluble dye that has simply penetrated into recording paper and that has been dry-fixed is "dyed", and the light fastness is very low.

(Addition of fine resin particles-water-soluble dye type ink)
As a measure for solving the problems of the water-soluble dye ink described above, the addition of resin fine particles such as emulsion and latex has been studied for a long time. JP-A-55
-18418 is for inkjet recording in which a latex which is "a kind of colloidal solution in which components such as rubber and resin are dispersed in water in the form of fine particles (particle diameter of about 0.01 to several μm) by an emulsifier" is added. There are suggestions for ink. The latex preferably used is styrene-
Butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, polychloroprene latex, vinylpyridine-styrene-butadiene latex, butyl rubber latex, polybutadiene latex, polyisoprene latex, polysulfide rubber latex, synthetic rubber-based latex, or, Examples of synthetic resin latexes include acrylic ester latex, styrene-butadiene resin latex, vinyl acetate latex, vinyl chloride latex, vinylidene chloride latex, and the like.

According to the proposal, the particle size of the latex particles that can be added is in the range of about 0.01 to several μm. However, if the particle size is less than 0.2 μm, the effect of preventing ink smearing on the recording paper is insufficient, and high recording quality cannot be obtained. The particle size is 1.0
If it is more than μm, the nozzle is frequently clogged and it becomes difficult to use it from the viewpoint of reliability. Therefore, it is considered that the practically usable range is approximately 0.2 to 1.0 μm. When such resin fine particles are added to the ink, attention must be paid to sedimentation or floating due to the difference in specific gravity between the particles and the medium. In the case of water-based ink, it is difficult for the specific gravity of the medium to deviate significantly from 1.0. In fine particles of about 0.2 μm or larger, the effect of gravity is larger than the diffusing force of particles due to Brownian motion, and therefore the difference between the particle specific gravity and the medium specific gravity is 0.1 in this region.
Hereafter, it is necessary to suppress it to preferably about 0.07 or less.

The specific gravity of the synthetic rubber-based latex exemplified in the patent proposal is in the range of about 0.9 to 1.0, and although such a condition is satisfied to some extent, most synthetic rubbers have unsaturated double bonds in the molecule. There is a problem in terms of light resistance and weather resistance. Further, when vulcanization is carried out to reduce unsaturated bonds, the fixing of particles onto recording paper is hindered, resulting in a problem in recording quality.
Further excessive vulcanization causes a specific gravity of 1.1 or more, which causes a problem of sedimentation. Furthermore, since such synthetic rubber latex has a low glass transition temperature, it is easy to form a film at room temperature, the nozzle is likely to be clogged when dried at the tip of an inkjet nozzle, and the dried product is soft and slightly sticky. Because it has, it is very difficult to remove. With respect to the synthetic resin latex exemplified in the patent, the specific gravity is 1.1 or more, and particularly in the case of a synthetic resin containing a halogen element, the specific gravity reaches 1.3 to 1.5. Sedimentation occurs in all areas. Furthermore, as can be said for all of these latexes, many of the emulsifiers used in the production of the latex are apt to promote foaming of the ink and lower the surface tension more than necessary, which is problematic.

Japanese Patent Application Laid-Open No. 54-146109 proposes a water-soluble dye type ink to which fine vinyl polymer particles swollen with a solvent and colored with an oily dye are added. Polymers preferably used are mainly (meth)
Acrylic ester-based copolymer fine particles are exemplified, and it is described that a glass transition temperature of 30 ° C. or lower is a suitable condition. There is no description about the particle size in the proposal. It is obvious that fine particles swollen with a solvent at such a low glass transition temperature have film-forming properties when dried at room temperature, and when such an ink is used, nozzle clogging may frequently occur. It is easily analogized.

(Pigment Dispersion Type Ink) In order to improve the drawbacks of the water-soluble dye type ink, it has been proposed to use carbon black or an organic pigment as a recording material. In such a pigment-dispersed ink, the water resistance of the ink is greatly improved. However, these pigments have a high specific gravity of 1.5 to 2.0, and attention must be paid to the sedimentation of dispersed particles. In order to stably disperse such a pigment having a high specific gravity, it is necessary to finely disperse the average particle diameter to about 0.1 μm or less, which results in a high dispersion cost and a very expensive ink. Further, if the particle size is 0.1 μm or less, the effect of preventing bleeding is insufficient and high quality recorded characters and images cannot be obtained. Further, there is a problem that the physical properties of the ink such as surface tension and foaming property are limited by the dispersant used for dispersion.

(Colored Resin Particle Ink) Proposals for coloring a water-dispersible resin with an oil-soluble dye or a hydrophobic dye have been made as an ink for ink jet recording. These are proposals relating to "ink using colored polymer particles as a recording agent". For example, JP-A-54-5850
4 proposes an ink in which a mixture of a hydrophobic dye solution and vinyl polymer fine particles is oil-in-water dispersed.
It is disclosed in the text that the vinyl polymer fine particles are swelled in the solvent of the dye solution by being mixed with the hydrophobic dye solution and further colored by the dye. Since the hydrophobic dye is used as the recording agent, the obtained image is said to have water resistance. According to the proposal, water is used as a continuous phase, and colored vinyl polymer particles swollen with a solvent are used as a dispersed phase so that water has control of ink viscosity and has a somewhat high viscosity (low volatility) as a solvent. It is allowed to use things.

Japanese Patent Laid-Open Nos. 55-139471 and 3-2
In 50069, an ink using emulsion-polymerized or dispersion-polymerized particles dyed with a dye is proposed. The purpose of the proposal is to prevent bleeding by using colored particles as a dispersoid and water (transparent) as a medium, as in Japanese Patent Laid-Open No. 54-58504. It is necessary to fix it on the recording paper by forming a film. It has been suggested that the desirable particle size is in the submicron region from the viewpoint of the necessity of film formation and ensuring of dispersion stability. The water dispersible resin is also a vinyl polymer in the proposal of deviation. In these vinyl polymers, it is difficult to perform high-concentration coloring because the dye has a low solubility in the resin. In Japanese Patent Laid-Open No. 54-58504, it is accepted that the polymer fine particles are swollen with a solvent to improve the dyeing property. In this case, however, there is a problem of nozzle clogging due to dry film formation at the nozzle tip. Occurs.

[0011]

As described above, it is difficult to improve the recording quality of the water-soluble dye type ink by the conventional technique, and it was developed to solve the problems of the water-soluble dye type ink. Satisfactory results have not been obtained even with the pigment-dispersed ink and the colored resin particle ink. As a result of intensive studies for improving the recording quality of water-based inks for inkjet recording, the present inventors have found that stability to sedimentation and reliability against nozzle clogging can be obtained only when specific resin fine particles are mixed in the ink. The present invention has been achieved by finding that both can be achieved and extremely high recording quality can be realized.

[0012]

Means for Solving the Problems That is, the present invention provides an ink jet recording ink containing resin fine particles, wherein the resin fine particles have a weight-average particle diameter of 0.05 to
An ink jet recording ink characterized by being non-spherical particles in the range of 2.0 μm, wherein the recording agent used in the ink jet recording ink is a water-soluble dye, and the medium contains water as a main component. An inkjet recording ink characterized in that the recording agent used in the inkjet recording ink is carbon black, the medium is an inkjet recording ink characterized in that the main component is water, The recording material used in the inkjet recording ink is an organic pigment, and the medium has water as a main component. The inkjet recording ink is characterized in that the sphericity of the non-spherical particles is 1.2 or more. An inkjet recording ink characterized in that the non-spherical resin fine particles contain lower alcohol and An ink for inkjet recording, which is non-swelling at room temperature with respect to alkylene glycol and / or alkanolamines, wherein the non-spherical resin fine particles are an ionomer comprising an ethylene / (meth) acrylic acid copolymer. An ink jet recording ink characterized by comprising a resin, wherein the non-spherical resin fine particles have a polyester resin as a main component. The present invention was mainly made with respect to a water-based inkjet recording ink, but is also applicable to inkjet recording using an oil-based ink. In addition, widely, recording media having irregularities on the surface or a fiber aggregate layer, specifically, general paper, some synthetic paper,
Alternatively, it can be applied to all recording means using a liquid recording material such as cloth or woven cloth.

In the present invention, a water-soluble dye, carbon black, an organic pigment or the like can be used as the recording agent. The water-soluble dye used in the present invention can be appropriately selected and used from known dyes. As water-soluble dyes, acid dyes, direct dyes, anionic dyes such as some food dyes,
Cationic dyes such as basic dyes are preferably used. More specifically, C.I. I. Direct Yellow
12, 24, 26, 33, 39, 44, 98, C.I. I.
Direct Red 1, 4, 17, 28, 81, 8
3, C.I. I. Direct Blue 6, 22, 2
5, 71, 86, 90, 98, 108, 202, C.I.
I. Direct Black 17, 19, 32, 5
1, 108, 146, C.I. I. Acid Yellow
11, 19, 25, 29, 38, 42, 61, 7
1, 127, 135, 161, C.I. I. Acid Re
d 6, 37, 51, 52, 80, 85, 87, 92,
94, 118, 155, 158, 180, 249, 25
6, 317, 318, C.I. I. Acid Violet
90 C. I. Acid Blue 9, 22, 23, 24,
40, 43, 78, 82, 93, 102, 104, 1
13, 117, 120, 127, 167, 229, 2
34 C. I. Acid Black 1, 2, 7, 24, 3
1, 52, 63, 112, 118, 119, 121,
122, 155, 156, C.I. I. Food Blac
k 2 C. I. Basic Yellow 11, 13, 1
4, 21, 28, 36, 40, 73, C.I. I. Basi
c Red 13, 14, 27, 36, 39, C.I. I.
Basic Violet 7, 11, 15, 27, 4
0, C.I. I. Basic Blue 3, 45, 67,
75, 77, etc. can be used suitably. These may be used alone or in combination of two or more. Inorganic salts are often mixed in such commercially available dyes during dye production, but since these inorganic salts and inorganic ions are known to adversely affect the stability of the ink, dialysis and recrystallization as much as possible. It is desirable to remove it by means such as conversion. The dye contains 0.3 to 15 wt% in the ink, preferably 0.5 to
10 wt%, and more preferably about 2.0 to 8.0 wt%.

The carbon black used in the present invention includes thermal black, acetylene black,
Channel black, furnace black, lamp black and the like can be used. As a method for water dispersion, a sand mill, a ball mill, an attritor, a paint shaker, or the like can be used. As a dispersant necessary for water dispersion, known anionic, nonionic, and cationic dispersants can be used as necessary.
However, in the present invention, the amount of the dispersant used should be minimized, and it is preferable to use a carbon black which has been surface-treated or graft-treated and which has been dispersed in water without using the dispersant. Carbon black is 0.3 to 15 wt% in the ink, preferably 0.5 to
10 wt%, and more preferably about 2.0 to 8.0 wt%. Dispersion particle size of carbon black is 0.1 μm
It is preferably not more than 0.08 μm, more preferably not more than 0.08 μm, and further preferably not more than 0.05 μm. If the dispersed particle size is large, the carbon black particles may be settled.

The organic pigment used in the present invention can be selected from known organic pigments and used as necessary. More preferably, CIE LCH system chromaticity coordinates (CIE
The color angle H in the LAB 1976 chromaticity coordinate (in the cylindrical coordinate system display) is in the range of 85 to 120 degrees, preferably 90 to 110 degrees, and the yellow dye is 230 to 270 degrees, and preferably 250 to 265 degrees. Cyan dye, 3
It is preferable to use a magenta dye having an angle of 30 to 360 degrees. Organic pigments include C.I. I. Pigment color,
C. I. Those that are classified as Vat color can be mainly used. In addition to these, a part of water-insoluble dye may be used as a pigment. As such a dye, it is possible to use a part of oil-based dye which is hydrophobic and does not dissolve in lower alcohols and glycols which are hydrophilic solvents.

More specifically, C.I. I. Pigment
Yellow 3, 13, 14, 15, 16, 17, 1
85, C.I. I. Pigment Red 81, 95,
122, 184 C.I. I. Pigment Violet 23 C.I. I. Pigment Blue 15, 16 and the like can be preferably used. As a method for water dispersion, a sand mill, a ball mill, an attritor, a paint shaker, or the like can be used. As a dispersant necessary for water dispersion, known anionic, nonionic, and cationic dispersants can be used as necessary. However, in the present invention, the amount of the dispersant to be used should be minimized, and it is preferable to use an organic pigment which has been surface-treated or graft-treated and which is dispersed in water without using the dispersant.

In the present invention, it is also possible to use fine particles of colored resin as a special example of the pigment. The fine particles of these colored resins are described in JP-A-54-5.
8504, JP-A-55-139471, JP-A-3-25
It is possible to use those obtained by the method described in 0069 and the like. Of these, those containing no solvent are preferably used. 0.3 to 1 organic pigment in the ink
5 wt%, preferably 0.5 to 10 wt%, more preferably 2.0 to 8.0 wt%. The dispersed particle size of the organic pigment is preferably 0.1 μm or less, and is 0.0
It is still more preferably 8 μm or less, further 0.0
It is preferably 5 μm or less. If the dispersed particle size is large, there is a concern that the organic pigment particles may settle. In the present invention, a small amount of water-soluble dye may be added to adjust the hue and the like. The water-soluble dye can be appropriately selected and used from known dyes. As the water-soluble dyes, acid dyes, direct dyes, anionic dyes such as some food dyes, and cationic dyes such as basic dyes are preferably used. The addition of a water-soluble dye causes a decrease in water resistance and must be minimized.

In general, a water-soluble organic compound is added to an ink jet recording ink for the purpose of improving the surface tension, viscosity, moisturizing property, freezing stability of the ink, adjusting the permeation rate into recording paper, and the like. No exception. As the water-soluble organic compound, methanol, ethyl alcohol,
Propanol, isopropanol, butanol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, thiodiglycol, propylene glycol, dipropylene glycol,
Polypropylene glycol, neopentyl glycol,
Compounds such as glycerin, monoethanolamine, diethanolamine, nitrile triethanol, ethylenediamine ethyl cellosolve, butyl cellosolve, tertiary butyl cellosolve, alkylene glycol monoether and the like can be used alone or in combination of a plurality of components. Particularly, it is preferable that alkylene glycols are added to the ink in an amount of 2 to 10 wt%, preferably 3 to 7 wt%.

The present invention has been made for the purpose of improving such an ink jet recording ink, mainly a water-based ink jet recording ink, in which resin fine particles are added for the purpose of improving the recording quality. The most important essential requirement that characterizes the present invention is that the weight average particle diameter of the resin fine particles contained in the ink is in the range of 0.05 to 2.0 μm, and the shape thereof is non-spherical. The non-spherical shape has an average asphericity of preferably 1.2 or more, more preferably 1.5 or more,
2.0 or more is still more preferable, and 2.5 or more is further preferable. Here, the asphericity is (1) the ratio of the perimeter of the projected figure to the circumference of the area-converted circle in the projected figure where the particles are projected onto the plane (2) the ratio of the major axis to the minor axis of the projected figure (3) It is defined by the ratio of the measured specific surface area to the specific surface area calculated from the volume-converted particle diameter, and preferably the smallest value among the numerical values calculated by these methods is taken as the non-sphericity.

The asphericity is preferably measured using an image processing device or the like. Since it is expected that a measurement error will occur considerably in actual measurement, it is necessary to calibrate in advance using particles having a high sphericity, for example, latex particles for microscope calibration, and then perform the measurement. The weight-converted particle diameter has the same meaning as the volume-converted particle diameter, and indicates the particle diameter of a solid sphere having the same weight or volume as the non-spherical particles. The particle size in terms of weight can be preferably determined by the Coulter counter method. Accurate measurement is difficult in a centrifugal sedimentation type particle size distribution analyzer because the particle shape affects the sedimentation velocity. Also in a light scattering type particle size distribution meter, the particle shape influences the scattered light intensity distribution, making accurate evaluation difficult. In addition, a sphere-converted diameter obtained by using an image processing apparatus can be used as an alternative means.

The weight-reduced particle size in the present invention is 0.05.
~ 2.0μm is essential, 0.05 ~ 1.0μ
The range of m is more preferable, the range of 0.08 to 0.5 μm is still more preferable, and the range of 0.1 to 0.3 μm is still more preferable. The specific gravity of the resin constituting the non-spherical particles of the present invention is not particularly limited, but preferably in the range of 0.9 to 1.3,
The range is preferably 0.95 to 1.10, more preferably 0.93 to 1.00, and further preferably 0.94 to 0.98. In the present invention, the lower limit of the particle size distribution is not limited as long as problems such as increase in ink viscosity do not occur, and a range up to about 0.01 μm is allowed. However, the upper limit of the particle size distribution is 2.
It should be controlled to about 0 μm, preferably 1.5 μm, and more preferably 1.2 μm or less. That is, the preferred particle size distribution in the present invention is not necessarily a normal distribution, but a shape with a small tail on the small diameter particle side is preferred. Particles with high monodispersity are not always preferred.

Such non-spherical resin fine particles are preferably non-swelling with respect to the water-soluble organic compound lower alcohol and / or alkylene glycol and / or alkanolamine which is an ink additive. The term "non-swelling" as used herein means that the resin does not dissolve in the organic compound as a physical property as a bulk of the resin and does not absorb the organic compound by 10 wt% or more, preferably 5 wt% or more. From another point of view, it means that a decrease in film forming temperature of 10 ° C. or higher, preferably 5 ° C. or higher does not occur in such an aqueous dispersion of resin particles. From another point of view, it means that the presence of such a water-soluble organic compound does not cause an effective change in the particle shape in the region of the resin softening temperature or below the glass transition temperature. When swelling to these water-soluble organic compounds supplementarily added to the ink, dry film formation of resin particles occurs at the nozzle tip,
Not only will it cause nozzle clogging, but the morphology of the non-spherical particles, which is an essential requirement of the present invention, will not be maintained, and the effects of the present invention will disappear.

The non-spherical particles used in the present invention are used as an aqueous fine dispersion, and the minimum film forming temperature in such an aqueous dispersion is preferably 40 ° C. or higher, and 60 ° C.
The above is more preferable, and even more preferably 70 to
It is preferably in the range of 100 ° C, and more preferably in the range of 80 to 100 ° C. In order to achieve such a minimum film forming temperature, ASTM D1525-
The Vicat softening point defined by 70 is preferably 40 to 100, more preferably 45 to 80 ° C, and further preferably 50 to 70 ° C. Further, the glass transition temperature is 40 ° C or higher, further 55 ° C.
It is preferable that it is above.

Generally, as methods for obtaining fine particles of resin, (1) suspension polymerization method (2) emulsion polymerization method (3) phase inversion (self) emulsion method, etc. are known. The microparticles obtained by the method are all substantially spherical. In the prior art, resin fine particles, emulsions, latexes, etc., which have been blended in ink jet recording inks, all use spherical fine particles obtained by these methods, and therefore sufficient recording quality improving effects cannot be obtained. . The non-spherical particles used in the present invention are preferably (1) mechanical pulverizing means (2) dispersion polymerization method (3) emulsion polymerization method, phase inversion (self) emulsification method It can be obtained by subsequent aggregation.

The material of the non-spherical particles preferably used in the present invention is mainly composed of an ethylene / (meth) acrylic acid copolymer, and is partially covered with an alkali metal ion, an alkaline earth metal ion, an ammonium ion or the like. It is a so-called ionomer resin that is ionically crosslinked. Such an aqueous dispersion of non-spherical particles of an ionomer resin can be obtained by a method other than emulsion polymerization, such as forced mechanical emulsification in which heating and mechanical stirring are used in combination, and trade names of Chemipearl S-100 and S-200. Same S-300, Same SA
-100 type [Mitsui Petrochemical Co., Ltd.] and the like can be exemplified. The material for the non-spherical particles preferably used in the present invention is a polyester resin. The polyester resin is obtained by polycondensation of mono-polyhydric carboxylic acids containing dicarboxylic acid as a main component and mono-polyhydric alcohols containing diol as a main component. Examples of the polycarboxylic acid used in the polyester resin include dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid,
Aromatic dicarboxylic acids such as 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid and diphenic acid,
Aromatic oxycarboxylic acids such as p-oxybenzoic acid and p- (hydroxyethoxy) benzoic acid, aromatic unsaturated polycarboxylic acids such as phenylenediacrylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecane Aliphatic dicarboxylic acids such as dicarboxylic acids, fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, hexahydrophthalic acid, tetrahydrophthalic acid, aliphatic unsaturated polycarboxylic acids, and fats such as cyclohexanedicarboxylic acid Examples of the cyclic dicarboxylic acid and the like, and examples of the polyvalent carboxylic acid include trivalent or higher polyvalent carboxylic acids such as trimellitic acid, trimesic acid and pyromellitic acid.

Examples of the monocarboxylic acid include benzoic acid, chlorobenzoic acid, bromobenzoic acid, parahydroxybenzoic acid, sulfobenzoic acid monoammonium salt, sulfobenzoic acid monosodium salt, cyclohexylaminocarbonylbenzoic acid, n-dodecylaminocarbonyl. Benzoic acid, tar
Char-butylbenzoic acid, naphthalenecarboxylic acid, 4-methylbenzoic acid, 3-methylbenzoic acid, salicylic acid, thiosalicylic acid, phenylacetic acid, acetic acid, propionic acid, butyric acid,
Examples thereof include isobutyric acid, octanecarboxylic acid, lauric acid, stearyl acid, and lower alkyl esters thereof. Examples of polyvalent alcohols used for the polyester resin include aliphatic polyvalent alcohols, alicyclic polyvalent alcohols, aromatic polyvalent alcohols and the like. As the aliphatic polyhydric alcohols, ethylene glycol, propylene glycol, 1,3-propanediol, 2,
3-butanediol, 1,4-butanediol, 1,5
-Pentanediol, 1,6-hexanediol, neopentyl glycol, dimethylol heptane, diethylene glycol, dipropylene glycol, 2,2,4-
Trimethyl-1,3-pentanediol, aliphatic glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol and trimethylol
Examples thereof include trioles such as ruethane, trimethylolpropane, glycerin, and pentaerythritol, and tetraols.

The alicyclic polyvalent alcohols are 1,4-
Cyclohexanediol, 1,4-cyclohexanedimethanol, spiroglycol, hydrogenated bisphenol A, ethylene oxide adduct and propylene oxide adduct of hydrogenated bisphenol A, tricyclodecanediol, Examples thereof include tricyclodecane dimethanol. As aromatic polyhydric alcohols, paraxylene glycol, metaxylene glycol, orthoxylene glycol, 1,4-phenylene glycol, and ethylene oxide adduct of 1,4-phenylene glycol. , Bisphenol A, ethylene oxide adduct of bisphenol A, propylene oxide adduct and the like. Other monoalcohols include lower alkyl alcohols, higher alkyl alcohols, tricyclodecane monomethanol and the like. Further, as a polyester polyol, a lactone-based polyester polyol obtained by ring-opening polymerization of lactones such as ε-caprolactone
And the like.

The polyester resin can be obtained using these monomers by a conventional method such as a vacuum polymerization method or a reduced pressure polymerization method. The former is a method used for polymerizing polyethylene terephthalate or the like, which is used for fibers, films, plastic bottles and the like, and a polyester having a relatively high molecular weight can be obtained. The latter is a method used when polymerizing an unsaturated polyester resin such as an alkyd resin, and a polyester having a relatively low molecular weight is obtained. In addition to these conventional methods, the polyester resin can be obtained by an acid chloride method or the like. The number average molecular weight of the polyester resin in the present invention is preferably 1000 to 20000, more preferably 1500 to 1000.
It is 0, and more preferably 2000 to 5000.
If the molecular weight is low, the resulting coating film may have insufficient physical properties. If the molecular weight is too high, dry film formation may be hindered. The glass transition temperature of the polyester resin in the present invention is preferably 40 ° C. or higher, more preferably 60 to 100 ° C.

The polyester resin in the present invention contains 20 to 2000 eq./ton of ionic groups from the viewpoint of water dispersion.
It is necessary to contain in the range of. Examples of the ionic group include an alkali metal sulfonate or ammonium sulfonate, an alkali metal carboxylate or an ammonium carboxylate, a sulfuric acid group, a phosphoric acid group, a phosphonic acid group, a phosphinic acid group or an ammonium salt thereof, an alkali metal. Anionic group such as salt, or first
A cationic group such as a primary to tertiary amine group can be used. The ionic group can be introduced by using the ionic group-containing monomer in combination, and in order to introduce the cationic group, 2-aminopropane-1,3dio-
, Nitrile triethanol and the like can be preferably used. In order to introduce an alkali metal sulfonate or ammonium sulfonate into the polyester, sulfoterephthalic acid, 5-sulfoisophthalic acid, 4
-Sulfophthalic acid, 4-sulfonaphthalene-2,7 dicarboxylic acid, 5 [4-sulfophenoxy] isophthalic acid,
The polyester may be copolymerized with an alkali metal salt or ammonium salt of a mono- or polyvalent carboxylic acid having a sulfonic acid group such as metasulfobenzoic acid. Ammonium ions, Li, Na, K, Mg, Ca, C as salts
Salts such as u and Fe are mentioned, and particularly preferable are K salt or Na salt. In the present invention, it is preferable to use 5-sodium sulfoisophthalic acid or metasodium sulfobenzoic acid.

The carboxylate group can be obtained by neutralizing the carboxyl group at the end of the polyester by adding a base at the time of dispersion in water described later. Examples of the method of introducing a carboxyl group into the polyester resin include a method of introducing a polyvalent carboxylic acid such as trimellitic anhydride and phthalic anhydride into the system at the final stage of polymerization of polyester in the vacuum polymerization method. Further, in the vacuum polymerization method, the carboxyl group remaining at the end of the polyester can be used as it is. As the base used for neutralization, in addition to alkaline substances such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonia and ammonium compounds include monoalkanolamines, dialkylmonoalkanolamines, dialkanolamines, monoalkyls. Dialkanolamine, trialkanolamine,
Are preferred, and trialkanolamines are preferred, and 2,2 ′, 2 ″ -nitrile triethanol, tripropanolamine, tributanolamine, and trihexanolamine are more preferred. The content of ionic groups is 20 to 2000 meq / 1
000 g is essential, 50-1000 m equivalent / 100
0 g is preferable, and further 100-500 meq /
A range of 1000 g is preferred. When the content of the ionic group is less than the predetermined amount, sufficient water dispersibility cannot be obtained. If the content of ionic groups is too large, the polyester resin becomes water-soluble and the desired water dispersion cannot be obtained. In the present invention, the use of carboxylic acid ammonium salt-based ionic groups is particularly preferable, and the use of carboxylic acid trialkanolamine salt is further preferable.

Since the ionic group-containing polyester resin has a phase inversion self-emulsifying property, a method of adding water after previously mixing the polyester resin and the water-soluble organic compound,
It can be obtained by a method of mixing and heating the ionic group-containing polyester resin, the water-soluble organic compound and water all together. Examples of water-soluble organic compounds include ethanol, isopropanol, butanol, ethylene glycol, propylene glycol, methyl cellosolve, ethyl cellosolve,
Butyl cellosolve, tertiary butyl cellosolve, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane and the like can be used. The water-soluble organic compound is preferably one that can be removed by azeotropic distillation after the ionic group-containing polyester resin is dispersed in water. The fine particles of the polyester resin obtained as described above are spherical particles having a particle diameter of about 0.01 to several μm. The average particle diameter can be controlled by the amount ratio of the polyester resin and the water-soluble organic compound, the ionic group content, and the like. In the present invention, it is preferable that the central particle diameter is adjusted to be approximately 0.01 to 0.2 μm or less.

The non-spherical particles of the present invention are obtained by, for example, secondary agglomerating the thermoplastic spherical particles thus obtained in a temperature range slightly exceeding the softening temperature and partially fusing them. Obtainable. The secondary aggregation is preferably performed in the slow aggregation region. Specifically, secondary aggregation can be caused by adding an electrolyte to an aqueous dispersion of fine resin particles and raising the temperature of the aqueous dispersion to a temperature near or slightly higher than the glass transition temperature or softening temperature of the resin. The amount of electrolyte added is preferably in a range not exceeding the critical aggregation concentration in the addition temperature range. The secondary aggregation method can be applied to resins other than the aqueous dispersion of polyester resin. The shape of the particles obtained by the secondary aggregation can be controlled by the treatment time, temperature, the amount of electrolyte added, and the like.

Fluorine-based or silicone-based defoaming agents can be added to the ink of the present invention. Furthermore, various fungicides and fungicides, and if necessary, inorganic and organic pigments may be added to the extent that transparency is not impaired. Further, addition of a trace amount of alkali metal ions or alkaline earth metal ions of about 5 to 50 ppm may be preferable in order to reduce the viscosity of the aqueous dispersion. The pH of the ink of the present invention is preferably 4 or higher, more preferably 6 or higher, even more preferably 7.5 or higher, and 7.5 to 9.5.
Is still more preferable. The viscosity of the ink of the present invention is preferably in the range of 1.5 to 30 centipoise and 1.8 to
15 centipoise is more preferred, and the range of 2.0-10 centipoise is even more preferred, and 3.0-6.0.
A range of centipoise is even more preferred. The inkjet recording ink of the present invention is preferably combined with an ink ejecting means that does not use thermal energy as a driving force.
The inkjet recording ink of the present invention is preferably combined with a means for fixing the ink by heating the recording paper to 40 ° C.

Conventionally, it has been attempted to add fine resin particles in order to improve the recording quality of an ink jet recording ink mainly containing an aqueous solution of a water-soluble dye or a water-based fine dispersion such as a pigment or carbon black. There is no example of the resin particles found in the conventional proposals in which the particle shape is specified. Unless otherwise noted, the resin particles found in such a proposal can be interpreted as being substantially spherical in view of the production method (emulsion polymerization, suspension polymerization). The attempt to improve the recording quality by adding such resin particles is basically based on the idea of suppressing bleeding by closing the gaps between fibers contained in the recording paper with particles larger than the gaps. . However, in the conventionally used substantially spherical particles, the gap between particles is large,
The fiber gap of the recording paper cannot be completely closed, and the effect of preventing ink smearing is insufficient. The non-spherical particles whose shape is regulated by the present invention are packed while being intricately entangled in the fiber gap, so that the particle gap is smaller than when spherical particles having the same particle diameter are used, and the recording quality improving effect is remarkable. . Further, the material of such non-spherical particles is required to have a low swelling property with respect to the hydrophilic solvent used in the ink for inkjet recording. This not only causes the nozzle to be clogged when the resin is softened and tends to adhere to the tip of the nozzle, but also prevents the resin from becoming spherical due to softening and swelling.

Further, the non-spherical particles of the present invention have a remarkable effect of improving the recording quality even with a smaller weight-converted spherical particle diameter than the substantially spherical particles. It can be interpreted that this is because the resin particles have a non-spherical shape and thus have a small mass and a large viscous resistance. Further, it is noteworthy in the present invention that the recording density is improved by adding such resin fine particles to the ink. This fact means that the recording agent, which permeates and diffuses along with the medium (water) along the fiber of the recording paper, is suppressed by the added resin fine particles to suppress bleeding. It can be understood that it is because a lot remains. This effect is conspicuously observed particularly in the resin fine particles satisfying the limiting conditions of the present invention, so that it is possible to evaluate the high effect of preventing bleeding.

The present invention will be more specifically described with reference to the following examples, but the present invention is not limited to the examples shown here. . [Preparation of polyester non-spherical particles] Cyclohexanedicarboxylic acid dimethyl ester 198 parts by weight, propylene glycol 165 parts by weight, tricyclodecane dimethanol 91 parts by weight in an autoclave equipped with a thermometer and a stirrer. , And 0.1 part by weight of tetrabutoxy titanate were charged and heated at 150 to 220 ° C. for 180 minutes to carry out a transesterification reaction. Then, after raising the temperature to 240 ° C.,
Gradually reduce the system pressure to 10 mmHg after 30 minutes,
The reaction was continued for 60 minutes. After that, the atmosphere in the autoclave was replaced with nitrogen gas and the pressure was adjusted to atmospheric pressure. While maintaining the temperature at 200 ° C., 4 parts by weight of trimellitic anhydride and 20 parts by weight of maleic anhydride were added and reacted for 60 minutes to obtain a copolymerized polyester resin (A). The obtained copolyester resin had a number average molecular weight of 3100, an acid value of 214 eq./ton and a glass transition temperature of 62 ° C.

200 parts by weight of polyester resin (A) and 100 parts of methyl ethyl ketone were placed in a four-necked 10 liter separable flask equipped with a thermometer, a condenser and a stirring blade.
70 parts by weight and 50 parts by weight of tetrahydrofuran
It melted at ℃. Next, 5 parts by weight of 2,2 ′, 2 ″ -nitrile triethanol as a base was added, and then 500 parts by weight of ion-exchanged water at 70 ° C. was added. In the system, phase inversion self-emulsification occurred and an aqueous dispersion was produced. Further, it was distilled in a distillation flask until the distillate temperature reached 103 ° C., and after cooling, water was added to obtain a polyester aqueous dispersion (B) having a solid content concentration of 25%. The average particle size of the finely dispersed particles present in the obtained polyester aqueous dispersion was 0.08 μm, the zeta potential was −55 mV, and the particle shape by SEM observation was almost spherical. 900 parts by weight of the obtained water dispersion, 45 parts by weight of styrene in which 2% by weight of azobisbutyl nitrile was dissolved, and 1N citric acid were placed in a four-necked 10-liter separable flask equipped with a thermometer, a condenser, and a stirring blade. 100 parts by weight of triethanolamine salt (corresponding to the electrolyte) was charged at room temperature, the temperature was raised to 95 ° C at 0.2 ° C / min while gently stirring, and the temperature was kept at 95 ° C for 120 minutes, followed by cooling with ice. . The treated aqueous dispersion was dialyzed using an artificial kidney module until the conductivity of the dialysate reached 5 μS / cm or less. The particles present in the obtained aqueous dispersion were a non-spherical shape in which several to about ten spherical particles were aggregated and fused in a dendrite shape by SEM observation. The asphericity of the particles obtained by changing the heating rate changed. By this method Table 1. Polyester fine particles having the particle size and shape shown in Table 1 were obtained. The asphericity (1) and (2) is S of the obtained particles.
EM photograph image processing device "Image Analyzer V1
(Manufactured by Toyobo Co., Ltd.), and the asphericity (3) was determined by the specific surface area calculated by the particle size distribution obtained by the Coulter counter method, the nitrogen adsorption / desorption method, and It was calculated from the specific surface area (average value of both companies) obtained by the mercury porosimetry.

[Table 1]

Here, the asphericity is the asphericity (1) the ratio of the outer peripheral length of the projected figure to the circumference of the area-converted circle in the projected figure in which the particles are projected on a plane. Ratio of major axis to minor axis Non-sphericity (3) The ratio of the measured specific surface area to the specific surface area calculated from the volume-converted particle size. The swelling property of the particles was evaluated by the degree of decrease in the minimum film-forming temperature when 10 wt% of isopropyl alcohol was added to the aqueous dispersion of resin particles. ○ When the film formation temperature decreases within 5 ° C ○: 5-10 ° C △: When 10 ° C is exceeded ×
And Further, non-spherical particles satisfying the requirements of the present invention and spherical particles not satisfying the requirements of the present invention were selected from commercially available resin particles and used in Examples and Comparative Examples. The characteristics of the resin particles used are shown in Table 1. Shown in Here S-100, S-2
00, S-300, and SA-100 are ethylene-methacrylic acid copolymers (80-90 wt% ethylene, 1 methacrylic acid 1) partially ionically cross-linked with alkali metal ions.
A water dispersion obtained by a soap-free emulsification method consisting of an ionomer resin containing 0 to 20 wt% as a main component, which is marketed by Mitsui Petrochemical Co., Ltd. as Chemipearl. Is a wax emulsion produced by Mitsui Petrochemical Co., Ltd.

E-3101 and E-5101 are spherical resin fine particles of styrene or acrylic and are commercially available from Nippon Paint Co., Ltd. under the trade name of Microgel. 240-V is a flat-shaped fine particle made of polystyrene resin, which is commercially available as Glossdale from Mitsui Toatsu Chemicals, Inc.

[Examples 1-9, Comparative Examples 1-5] Aqueous dispersion of carbon black "Micro Pigmo Black WM"
BK-5 "(Orient Chemical Co., Ltd., average particle size 0.05
μm), deionized water, a predetermined amount of ethylene glycol, isopropyl alcohol, and nitrile triethanol were added and mixed. Furthermore, an aqueous dispersion of resin fine particles prepared separately was gently added dropwise with stirring and mixed sufficiently, and then filtered through a 1.0 μm membrane filter to prepare an inkjet recording ink having the following composition. The filtration operation was omitted only when W-500 was used. Prototype ink Carbon black (converted to pigment content) 10.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitrile triethanol 0.2 wt% Resin fine particles (nonvolatile content) 5.0 wt% Water remaining Prototype ink Inkjet printer IO73
5X [manufactured by Sharp Corporation] was charged, printing was performed on recycled paper, and the recording quality was visually evaluated.

Further, a parallel line pattern having a thin line of 1-dot width and a line of 1-dot width is printed on a calligraphy half-paper, and the original line width calculated from the dot pitch and the line width of the line actually printed are drawn. The fat width was determined to be the width of the blur. Inkjet printer with ink loaded at 40 ℃ 30% RH
After left for 1 week in the high temperature dry atmosphere, the printer was restarted and the nozzle clogging property was evaluated by the number of times of head cleaning required for head recovery. The results are shown in Table 2. Shown in

[Table 2] Table 2. Medium, recording quality (visual inspection): 1 dot width, beard noise per 1 cm line length, less than 1 ◎ 1-2, ○ 2-4, △ 4 or more × Clogging resistance: Number of cleaning operations required before recovery When recovered by cleaning when the power is turned on ◎ Forced cleaning recovers in 1 time ○ Forced cleaning recovers in 2 to 3 times △ Does not recover in 3 times in forced cleaning and is ×.

[Examples 10 to 18 and Comparative Examples 6 to 10] Ink jet recording inks having the following compositions were prepared in the same procedure as in Example 1 and evaluated in the same manner. The results are shown in Table 3. Shown in Prototype ink) Water-soluble dye C.I. I. Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitrile triethanol 0.2 wt% Resin fine particles 7.0 wt% Water residue

[Table 3]

Example 19 Organic pigment "Palioto"
Yellow S1155 (C.I. Pigmen
t Yellow 185 "(manufactured by BASF) 20 parts by weight, an aqueous solution (nonvolatile content 20 wt%) of a partially esterified product of styrene-maleic acid copolymer resin (acid value 2000 eq / ton).
%) 10 parts by weight and 70 parts by weight of ion-exchanged water were placed in an attritor and dispersed for about 3 hours. The obtained dispersion is filtered with 5B filter paper and then filtered with a membrane filter 1.0 μm, a membrane filter 0.4 μm and a membrane filter 0.2 μm to finally obtain a yellow pigment water dispersion having an average particle diameter of 0.08 μm. Obtained. As an organic pigment, "Permanent Rubine F6B
(C.I. Pigment Red 184) "(HO
(Manufactured by ECHST) was similarly used to obtain a magenta pigment aqueous dispersion. As an aqueous dispersion of cyan organic pigment, "Levan
yl Blue GZ ”(manufactured by BAYER, average particle size 0.06 μm, CI Pigment Blue 15 finely dispersed using a nonionic dispersant) was prepared.

Printex 150 as a black pigment
Using T [DEGUSSA] carbon black, a black aqueous dispersion was prepared in the same manner as yellow and magenta. Using the resulting pigment water dispersion, trial ink organic pigment + dispersant (non-volatile content) 10.0 wt% ethylene glycol 5.0 wt% isopropyl alcohol 0.8 wt% nitrile triethanol 0.2 wt% Chemipearl S-200 (Nonvolatile content) Trial ink was adjusted so that 5.0 wt% water remained. The obtained trial ink was charged into an inkjet printer IO735X (manufactured by Sharp Corporation), and a photographic full color image having continuous gradation was printed on plain paper for PPC. The obtained image showed a clear and good color tone, and it was preferable to develop a light intermediate color. When the recorded dots were observed with an optical microscope, the independent dots were reproduced in a substantially circular shape.

[0045]

As described above, the ink jet recording ink of the present invention has excellent characteristics as an ink for ink jet recording that is capable of high quality and high quality recording images and printing and has high resistance to nozzle clogging. It is a thing.

Front page continued (72) Inventor Yozo Yamada 1-1-1 Katata, Otsu City, Shiga Prefecture Inside Toyobo Co., Ltd.

Claims (8)

[Claims] 1. An ink jet recording ink containing resin fine particles, wherein the resin fine particles are non-spherical particles having a weight-converted average particle diameter of 0.05 to 2.0 μm. Ink. 2. The inkjet recording ink according to claim 1, wherein the recording agent used in the inkjet recording ink is a water-soluble dye, and the medium contains water as a main component. 3. The inkjet recording ink according to claim 1, wherein the recording agent used in the inkjet recording ink is carbon black, and the medium contains water as a main component. 4. The ink for ink jet recording according to claim 1, wherein the recording material used in the ink for ink jet recording is an organic pigment, and the medium contains water as a main component. 5. The ink for ink jet recording according to claim 1, wherein the sphericity of the non-spherical particles is 1.2 or more. 6. The ink jet recording ink according to claim 1, wherein the non-spherical resin fine particles are non-swellable with a lower alcohol and / or an alkylene glycol and / or an alkanolamine at room temperature. 7. The non-spherical resin fine particles are ethylene /
The ink for inkjet recording according to claim 1, which comprises an ionomer resin composed of a (meth) acrylic acid copolymer. 8. The ink for ink jet recording according to claim 1, wherein the non-spherical resin fine particles contain a polyester resin as a main component.