JPH08239605A - Ink jet recording ink - Google Patents

Abstract

PURPOSE: To obtain an ink jet recording ink which enables high-quality image recording and printing and has both a high-reliability of clogging resistance and a high storage stability. CONSTITUTION: This ink is a water-sol.-dye ink which contains 0.5-15wt.% fine synthetic resin particles comprising an ethylene-propylene copolymer, a copolymer made mainly from methylstyrene, an ethylene-(meth)acrylic acid copolymer, an ionomer resin, etc., and having a specific gravity of 0.91-1.05 and an average particle size of 0.2-1.0μm.

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 on a lighter, a large signboard, a poster printer, etc., a cloth, a carpet, a wallpaper, etc. More specifically, an ink using a water-soluble dye as a recording material. It is about.

[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. In the proposal, the particle diameter of latex particles that can be added is said to be 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. Further, when the particle size is 1.0 μm or more, the nozzle is frequently clogged, and it is difficult to use it from the viewpoint of reliability. Therefore, the practically usable range is approximately 0.2 to 1.0 μ.
It is considered to be in the range of m.

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. Since the effect of gravity is greater in fine particles having a size of about 0.2 μm or more as compared with the diffusing force of the particles due to Brownian motion, the difference between the particle specific gravity and the medium specific gravity is 0.1 or less, preferably 0. It is necessary to suppress it to about 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 an unsaturated double bond in the molecule. There is a problem in 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, so that the bleeding prevention effect is exhibited. Sedimentation occurs in all the range of particle size. Furthermore, as can be said for all of these latices, many of the emulsifiers used in the production of latices facilitate the foaming of ink,
There are many problems because the surface tension is lowered more than necessary.
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 acid ester-based copolymer fine particles, 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 Type Ink) A proposal for coloring a water-dispersible resin with an oil-soluble dye or a hydrophobic dye has 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. JP-A-55-139471 and JP-A-3-250069 propose inks using emulsion-polymerized or dispersion-polymerized particles dyed with a dye.
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.

In each of the proposals, the water-dispersible resin is a vinyl polymer. 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. Japanese Patent Laid-Open No. 4-
In 185672, in the ink composed of colored resin particles and an aqueous medium, a water-soluble compound is dissolved in the aqueous medium so that the specific gravity difference between the colored resin particles and the aqueous medium becomes 0.0
It is proposed that the particle size be 4 or less to prevent the sedimentation of particles. Here, it is said that inorganic salts are preferably used as the water-soluble compound. However, when such an inorganic salt is dissolved in an aqueous medium, the ionic strength in the system increases and the stability of the dispersion system decreases, so that the colored resin particles agglomerate and cannot maintain the fluid characteristics of the inkjet ink. JP-A-4-185673, JP-A-4-18567
In No. 4, the effective specific gravity is lowered by swelling the colored resin particles with a solvent in the ink composed of the colored resin particles and the aqueous medium, and the specific gravity difference between the colored resin particles and the aqueous medium is 0.04 or less. Is proposed. In such a case, it is difficult to avoid nozzle clogging as described above.

[0010]

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. The present inventors aim to improve the recording quality of a water-soluble dye type ink for inkjet recording, and particularly in a water-soluble dye type ink containing resin fine particles, a remarkable recording quality is obtained only when certain specific resin fine particles are added. The inventors have found that it is possible to achieve both improvement, stability against particle settling, and reliability against nozzle clogging, and reached the present invention.

[0011]

That is, the present invention provides an ink jet recording ink using a water-soluble dye as a recording agent, which has a specific gravity of 0.9 to 1.05 and an average particle diameter of 0.2.
An ink jet recording ink characterized by containing 0.5 to 15% by weight of synthetic resin fine particles having a particle size of 1.0 to 1.0 μm, wherein the synthetic resin fine particles have a specific gravity of 0.93 to 1.00.
And the average particle size is in the range of 0.3 to 0.8 μm. The inkjet recording ink is characterized in that the synthetic resin fine particles have a lower alcohol and / or an alkylene glycol and / or an alkanolamine. The inkjet recording ink is characterized in that it is non-swellable, and the synthetic resin fine particles are composed of a (co) polymer containing 50% by weight or more of ethylene and / or propylene. And the synthetic resin particles are composed of a (co) polymer composed of 50% by weight or more of methylstyrene, and the synthetic resin particles are an ethylene / (meth) acrylic acid copolymer. An inkjet recording ink comprising:

Further, the synthetic resin fine particles are ethylene /
An ink-jet recording ink comprising an ionomer resin composed of a (meth) acrylic acid copolymer and having a Vicat softening point in the range of 40 to 100 ° C., wherein the synthetic resin fine particles do not use an emulsifier. An ink for inkjet recording characterized by being obtained by

The water-soluble dye used in the present invention can be appropriately selected from known dyes and used. 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. More specifically, C.I. I. Direct Y
ellow 12, 24, 26, 33, 39, 44, 9
8, C.I. I. Direct Red 1, 4, 17, 2
8, 81, 83, C.I. I. Direct Blue
6, 22, 25, 71, 86, 90, 98, 108, 2
02, C.I. I. Direct Black 17, 1
9, 32, 51, 108, 146, C.I. I. Acid
Yellow 11, 19, 25, 29, 38, 42,
61, 71, 127, 135, 161, C.I. I. Ac
id Red 6, 37, 51, 52, 80, 85, 8
7, 92, 94, 118, 155, 158, 180, 2
49, 256, 317, 318, C.I. I. Acid V
iolet 90 C.I. 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. Such a dye is contained in the ink in an amount of 0.3 to 15% by weight,
Preferably 0.5 to 10 wt%, more preferably 2.0
Approximately 8.0 wt% is compounded. A water-soluble organic compound is added to an ink using such a water-soluble dye for the purpose of adjusting the surface tension, viscosity, moisturizing property of the ink, penetration rate into recording paper, and the like. 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, glycerin, monoethanolamine, diethanolamine, nitrile triethanol, ethylenediamine ethyl cellosolve, Butyl cellosolve,
A compound such as tertiary butyl cellosolve or an alkylene glycol monoether can be used alone or in combination of a plurality of components. Particularly, alkylene glycols are contained in the ink in an amount of 2 to 10% by weight, preferably 3 to 7%.
It is preferable to add about wt%.

The features of the present invention are that an ink mainly composed of such a water-soluble dye has a specific gravity of 0.9 to 1.05 and an average particle diameter of 0.
0.5 to 15% by weight of synthetic resin fine particles of 2 to 1.0 μm
It is to contain. The specific gravity of the synthetic resin fine particles is preferably in the range of 0.93 to 1.00, more preferably 0.94 to 0.98. The average particle size is preferably 0.3 to 0.8 μm, more preferably 0.35 to 0.7 μm, and still more preferably 0.4 to 0.6 μm. If the specific gravity is less than this range, there is a possibility of phase separation due to floating of particles when the ink is stored for a long time. Sedimentation may occur if the specific gravity exceeds this range. On the other hand, if the average particle size is less than this range, the improvement of the recording quality is insufficient, and bleeding is likely to occur especially on a paper of poor quality such as recycled paper. When the average particle size exceeds this range, not only the risk of phase separation due to sedimentation or floating rises, but also the risk of nozzle clogging increases. Even more interestingly, the addition of particles having a particle size exceeding this range gradually reduces the bleeding prevention effect. It is considered that this is because the diameter of the particles is too large and the effect of the particles blocking the fiber gaps of the recording paper is rather reduced. 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 the lower limit is about 0.01 μm.
Ranges up to the degree are acceptable. However, the upper limit of the particle size distribution needs to be controlled to about 2.0 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.

Further, such synthetic resin fine particles are required to be non-swellable with respect to the water-soluble organic compound lower alcohols and / or alkylene glycols and / or alkanolamines which are ink additives. Here, the non-swelling property means that the resin does not dissolve in the organic compound as a physical property as a bulk,
It means a resin that does not absorb 10 wt% or more, preferably 5 wt% or more of the organic compound, and from another viewpoint, 10 ° C. or more in an aqueous dispersion of such resin particles,
It preferably means that the film formation temperature does not decrease by 5 ° C. or more. When swelling to these water-soluble organic compounds that are supplementarily added to the ink, dry film formation of resin particles occurs at the tip of the nozzle, which causes nozzle clogging.

In the resin fine particles used in the present invention, the minimum film forming temperature is preferably 40 ° C. or higher, and 60
It is more preferable that the temperature is ℃ or higher, and even more
It is preferably in the range of -100 to 100 ° C, and more preferably in the range of 80 to 100 ° C. 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.

The resin fine particles having such properties include
Examples thereof include (co) polymers containing 50% by weight or more of ethylene and / or propylene, (co) polymers containing 50% by weight or more of methylstyrene, and resin fine particles of ethylene / (meth) acrylic acid copolymer. . As the methylstyrene, any isomer of α, ortho, meta and para positions may be used, but one having a methyl group at the meta position or the para position is particularly preferable. Such resin fine particles can be obtained by any method such as the so-called emulsion polymerization method, but when the resin fine particles obtained by the emulsion polymerization method are particularly used in the present invention, those obtained by a method using no emulsifier such as soap-free emulsion polymerization Is preferably used. This is because emulsifiers and the like often have an unfavorable effect on various properties of the inkjet recording ink. The resin particles particularly preferably used in the present invention are ethylene /
It is preferable to use an aqueous dispersion composed of a so-called ionomer resin which contains a (meth) acrylic acid copolymer as a main component and is partially ionically cross-linked with an alkali metal ion, an alkaline earth metal ion, or an ammonium ion. . An aqueous dispersion of such a 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 the degree of freedom in the method of obtaining a fine dispersion of resin particles without using an emulsifier. Is high. Examples of water dispersions of such resins include trade names of Chemipearl S-100 and S-20.
0, the same S-300, the same SA-100 type [manufactured by Mitsui Petrochemical Co., Ltd.] 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, the 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.

As described above, it is widely known that the recording quality is improved when the resin fine particles are added to the water-soluble dye type ink, and many patent proposals have been made. However, they are concerned only with the recording quality, and do not give any consideration to the storage stability of the ink itself and the reliability against clogging of inkjet nozzles. An object of the present invention is to provide an ink that realizes high recording quality while satisfying storage stability and reliability against clogging, and only a specific one of many resin fine particles has this purpose. This was done as a result of finding satisfaction. In the present invention, the specific gravity of the resin and the particle size of the dispersed particles are specified at the same time, but the compatibility between the storage stability and the recording quality can be achieved only by satisfying both of them. Further, by satisfying this condition, having a specific softening temperature and realizing a property that the physical properties thereof are not significantly affected by other ink addition components, the reliability against nozzle clogging can be secured. Further, it is noteworthy in the present invention that the recording density is improved by adding such resin fine particles to the water-soluble dye type ink. This fact means that the dye component that permeates and diffuses along with the medium (water) along the fibers of the recording paper is suppressed by the added resin fine particles, and bleeding is suppressed,
It can be understood that a relatively large amount remains near the surface of the recording paper. 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 described in more detail below with reference to examples, but the present invention is not limited to the examples shown here.

Example 1 A water-soluble dye was dissolved in deionized water, and predetermined amounts 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. Prototype ink (1) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitrile triethanol 0.2 wt% Ethylene-propylene copolymer fine particles (non-volatile content 5.0 wt% water residue The ethylene-propylene copolymer fine particles are an aqueous dispersion of copolymer resin particles obtained by soap-free emulsion polymerization consisting of 90 wt% ethylene and 10 wt% propylene, and have an average particle diameter of 0. 50 μm Resin specific gravity 0.96 Minimum film forming temperature 95 ° C. Vicat softening point 76 ° C. The resin did not dissolve in methanol, ethanol, isopropyl alcohol, ethylene glycol, and nitrile triethanol, and no swelling was observed. Furthermore, even when 10 wt parts of isopropyl alcohol was added to 100 wt parts of the water dispersion prepared to have a nonvolatile concentration of 20 wt%, the minimum film formation did not change, and the particle size did not change, so the swelling property with lower alcohol is actually It was judged not to rise. The viscosity of the ink was adjusted to 2.8 centipoise and the surface tension was adjusted to 52 dyn / cm. Also, in the following Examples and Comparative Examples, the ink viscosity is in the range of 2.5 to 3.2 centipoise and the surface tension is 48 to 54 dyn / cm from the viewpoint of comparison under certain conditions.
Was adjusted to fall within the range. The average particle diameter was measured by a light-scattering type particle size distribution meter, the resin specific gravity was measured by a float-sink method, the minimum film-forming temperature was measured by a conventional method, and the Vicat softening point was measured by a method according to ASTM D1525-70. The obtained trial ink (1) was charged into an inkjet printer IO735X (manufactured by Sharp Corporation), printed on recycled paper, and the recording quality was visually evaluated. Also, print a parallel line pattern with a thin line of 1-dot width and a line of 1-dot width on calligraphy paper, and obtain the line thickness from the original line width calculated from the dot pitch and the line width actually printed. , The width of the blur. At the same time, the optical density (optical density meter manufactured by Macbeth) of the solid print portion was measured. Also, use an ink jet printer with ink loaded at 40 ° C 30%
After left in a high temperature dry atmosphere of RH for one week, the printer was restarted, and the nozzle clogging property was evaluated by the number of times of head cleaning required for head recovery. Further, a test tube having a depth of 10 cm was filled with a trial ink, sealed, and allowed to stand for 3 months, and after 3 months, the presence or absence of a precipitate at the bottom of the test tube, and an ink sampled from 5 mm below the liquid level,
The storage stability was evaluated based on the solid content concentration ratio with the ink sampled from a portion 1 cm above the bottom. The results are shown in Tables (Table 1 and Table 2).

[0022]

[Table 1]

[0023]

[Table 2] Table 1. Table 2. Medium MFT: Minimum film forming temperature SP: Vicat softening point Recording quality (visual): 1 dot width Whisker-like noise per 1 cm line length 1 or less ◎ 1-2, ○ 2-4 △ 4 or more × Clogging resistance Property: Number of cleaning operations required before recovery When recovered by cleaning when power is turned on ◎ Forced cleaning recovers once 1 ○ Forced cleaning recovers 2 to 3 times △ Not recovered after 3 times forced cleaning ×

[0024]

Example 2 An ink jet recording ink having the following composition was prepared in the same procedure as in Example 1 and evaluated in the same manner. The results are shown in the table. Prototype Ink (2) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitrile triethanol 0.2 wt% Paramethylstyrene-butyl methacrylate copolymer Fine particles (nonvolatile matter equivalent) 5.0 wt% water residue Paramethylstyrene-butyl methacrylate copolymer fine particles are obtained by soap-free emulsion polymerization consisting of 75% by weight of paramethylstyrene, 20% by weight of butyl methacrylate and 5% by weight of divinylbenzene. The obtained copolymer resin particle aqueous dispersion has an average particle diameter of 0.45 μm, a resin specific gravity of 1.02, a minimum film forming temperature of 102 ° C., and a Vicat softening point of 95 ° C. This resin did not dissolve in methanol, ethanol, isopropanol, ethylene glycol, and nitrile triethanol, but some swelling was observed in methanol. 10 wt% of isopropyl alcohol was added to 100 wt% of the aqueous dispersion prepared to have a nonvolatile concentration of 20 wt%.
Although the minimum film formation decreased by about 4 ° C. when part was added, it was judged that the swelling property with a lower alcohol was low because there was no detectable change in the particle size.

[0025]

Example 3 An inkjet recording ink having the following composition was prepared by the same procedure as in Example 1 and evaluated in the same manner. The results are shown in the table. Prototype Ink (3) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitrile triethanol 0.2 wt% Ionomer resin fine particles S-200 ) 5.0 wt% water residue Here, the ionomer resin fine particles are ethylene-methacrylic acid copolymer partially ionically crosslinked by alkali metal ions (ethylene 80-90 wt%, methacrylic acid 10-
20 wt%) obtained by a soap-free emulsification method and marketed by Mitsui Petrochemical Co., Ltd. as Chemipearl S-200, having an average particle diameter of 0.43 μm and a resin specific gravity of 0.95. The film temperature is 85 ° C and the Vicat softening point is 57 ° C. The resin did not dissolve in methanol, ethanol, isopropyl alcohol, ethylene glycol, and nitrile triethanol, and no swelling was observed. Furthermore, even when 10 wt parts of isopropyl alcohol was added to 100 wt parts of the water dispersion prepared to have a nonvolatile concentration of 20 wt%, the minimum film formation did not change, and the particle size did not change, so the swelling property with lower alcohol is actually It was judged not to rise.

[0026]

Example 4 An ink jet recording ink having the following composition was prepared in the same procedure as in Example 1 and evaluated in the same manner. The results are shown in the table. Prototype ink (4) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitrile triethanol 0.2 wt% Ionomer resin fine particles S-300 (Nonvolatile component conversion) ) 2.0 wt% water residue Here, the ionomer resin fine particles are ethylene-methacrylic acid copolymers (ethylene 80 to 90 wt%, methacrylic acid 10 to 10) partially ionically cross-linked by alkali metal ions.
20 wt%) obtained by a soap-free emulsification method and marketed by Mitsui Petrochemical Co., Ltd. as Chemipearl S-300, having an average particle diameter of 0.53 μm and a resin specific gravity of 0.95. The film temperature is 94 ° C and the Vicat softening point is 67 ° C. It was judged that this resin, like the ionomer resin used in Example 3, has virtually no swelling property with a lower alcohol.

[0027]

Example 5 An inkjet recording ink having the following composition was prepared in the same procedure as in Example 1 and evaluated in the same manner. The results are shown in the table. Prototype ink (5) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitrile triethanol 0.2 wt% Modified ionomer resin fine particles SA-100 (nonvolatile content) 2.0 wt% water residue The modified ionomer resin fine particles here are ethylene-methacrylic acid copolymers (ethylene 80-90 wt%, methacrylic acid 1
It is an aqueous dispersion obtained by a soap-free emulsification method consisting of a graft copolymer obtained by further grafting styrene to 0 to 20 wt%), which is marketed by Mitsui Petrochemical Co., Ltd. as Chemipearl SA-100, and has an average value. Particle diameter 0.75 μm Resin specific gravity 1.00 Minimum film forming temperature 70 ° C. Vicat softening point 55 ° C. This resin did not dissolve in methanol, ethanol, isopropanol, ethylene glycol, and nitrile triethanol, but some swelling was observed in methanol. 10 wt% of isopropyl alcohol was added to 100 wt% of the aqueous dispersion prepared to have a nonvolatile concentration of 20 wt%.
In the case of adding 1 part, the minimum film formation decreased by about 2 ° C., but there was no detectable change in the particle size, so it was judged that the swelling property with a lower alcohol was low.

[0028]

Comparative Example 1 An ink jet recording ink having the following composition was prepared in the same procedure as in Example 1 and evaluated in the same manner. The results are shown in the table. Prototype Ink (6) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitriletriethanol 0.2 wt% Water residue This prototype ink contains resin particles There is no so-called typical water-soluble dye type ink.

[0029]

Comparative Example 2 An ink jet recording ink having the following composition was prepared in the same procedure as in Example 1 and evaluated in the same manner. The results are shown in the table. Prototype ink (7) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitrile triethanol 0.2 wt% Vinylidene chloride copolymer latex (Non-volatile conversion) ) 5.0 wt% water residue The vinylidene chloride copolymer latex here is an emulsion dispersion latex using an aliphatic soap of vinylidene chloride-vinyl chloride copolymer. Average particle diameter 0.15 μm Resin specific gravity 1.36 Minimum film forming temperature 135 ° C. Vicat softening point 125 ° C. As a result of the same evaluation as in Example 1, this resin was judged to have low swelling property with a lower alcohol.

[0030]

Comparative Example 3 An ink jet recording ink having the following composition was prepared in the same procedure as in Example 1 and evaluated in the same manner. The results are shown in the table. Prototype ink (8) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitrile triethanol 0.2 wt% Vinylidene chloride copolymer latex (Non-volatile conversion) ) 5.0 wt% water residue The vinylidene chloride copolymer latex is an emulsion-dispersed latex using a vinylidene chloride-vinyl chloride copolymer aliphatic soap as in Comparative Example 1. Average particle diameter 0.45 μm Resin specific gravity 1.36 Minimum film forming temperature 135 ° C. Vicat softening point 125 ° C., which is larger than that of Comparative Example 1. As a result of the same evaluation as in Example 1, this resin was judged to have low swelling property with a lower alcohol.

[0031]

Comparative Example 4 An ink jet recording ink having the following composition was prepared by the same procedure as in Example 1 and evaluated in the same manner. The results are shown in the table. Prototype Ink (9) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitriletriethanol 0.2 wt% Styrene-butadiene copolymer latex (non-volatile content) 5.0 wt% water residue The styrene-butadiene copolymer latex is an emulsion-dispersed latex using a copolymer aliphatic soap containing 25 wt% styrene. Average particle diameter 0.38 μm Resin specific gravity 1.06 Minimum film forming temperature 24 ° C. Vicat softening point 10 ° C. This resin was dissolved in methanol, ethanol and isopropanol. It did not dissolve in ethylene glycol or nitrile triethanol. When 10 wt parts of isopropyl alcohol was added to 100 wt parts of the water dispersion prepared to have a nonvolatile concentration of 20 wt%, the minimum film formation was lowered by 24 ° C. or more, that is, when the freezing point was not lower than the freezing point, the film was formed by natural drying. Therefore, the swelling property was judged to be very high.

[0032]

Comparative Example 5 An inkjet recording ink having the following composition was prepared in the same procedure as in Example 1 and evaluated in the same manner. The results are shown in the table. Prototype Ink (10) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitriletriethanol 0.2 wt% Polymethylmethacrylate latex (non-volatile content) 5 0.0 wt% water residue Polymethylmethacrylate latex is commercially available as Microgel P-5002 [Nippon Paint]. The average particle diameter is 0.52 μm, the resin specific gravity is 1.19, and the minimum film forming temperature is 120 ° C. and the Vicat softening point is 110 ° C. This resin did not dissolve in methanol, ethanol, isopropanol, ethylene glycol, and nitrile triethanol, but showed slightly softened and swollen surface in methanol and isopropanol. Aqueous dispersion 100 with nonvolatile concentration adjusted to 20 wt%
When 10 wt parts of isopropyl alcohol was added to wt parts, the minimum film formation was lowered by 12 ° C. Although the swelling property was not so high, it was considered to be slightly recognized.

[0033]

Comparative Example 6 An ink jet recording ink having the following composition was prepared in the same procedure as in Example 1 and evaluated in the same manner. The results are shown in the table. Prototype ink (11) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitrile triethanol 0.2 wt% Acrylic copolymer latex ) 5.0 wt% water residue The acrylic copolymer latex here is copolymer latex particles obtained by emulsion polymerization of methyl methacrylate, ethyl methacrylate and butyl methacrylate. Average particle diameter 0.45 μm Resin specific gravity 1.07 Minimum film forming temperature 84 ° C. Vicat softening point 80 ° C. This resin is ethanol, ethylene glycol,
Although it did not dissolve in nitrile triethanol,
Some solubility was observed in methanol and isopropanol. When 10 parts by weight of isopropyl alcohol was added to 100 parts by weight of the aqueous dispersion prepared to have a nonvolatile concentration of 20% by weight, the minimum film formation was lowered by about 30 ° C., and it was judged that the swelling property was high.

[0034]

Comparative Example 7 An ink jet recording ink having the following composition was prepared in the same procedure as in Example 1 and evaluated in the same manner. However, the filtration step using a 1.0 μm membrane filter was omitted. The results are shown in the table. Prototype Ink (12) Water-soluble dye CI Direct Blue 86 Purified product 1.0 wt% Ethylene glycol 5.0 wt% Isopropyl alcohol 0.8 wt% Nitrile triethanol 0.2 wt% Polyolefin fine particles W-500 (calculated as nonvolatile content) 5.0 wt% water residue Polyolefin fine particles are an aqueous dispersion obtained by soap-free emulsification method consisting of low molecular weight polyolefin (mainly polyethylene), and marketed by Mitsui Petrochemical Co., Ltd. as Chemipearl W-500. The average particle size is 2.50 μm, the resin specific gravity is 0.92, the minimum film forming temperature is 90 ° C., and the Vicat softening point is 38 ° C. The resin did not dissolve in methanol, ethanol, isopropyl alcohol, ethylene glycol, and nitrile triethanol, and no swelling was observed. Furthermore, even when 10 wt parts of isopropyl alcohol was added to 100 wt parts of the water dispersion prepared to have a nonvolatile concentration of 20 wt%, the minimum film formation did not change, and the particle size did not change, so the swelling property with lower alcohol is actually It was judged not to rise.

[0035]

[Comparative Example 8] Inkjet printer ink "BJ"
I-201M "was used as a comparative ink. "BJI-
201M "is an inkjet printer BJC-600
It is a commercially available magenta ink of J [manufactured by CANON], and is known to be an aqueous ink using a water-soluble dye as a main recording agent. The following evaluation was performed in the same manner as in Example 1. The results are shown in the table.

[0036]

Comparative Example 9 Ink for inkjet printer "MJ
"IC2" was used as a comparative ink. "MJIC2" is commercially available as a black ink for inkjet printer MJ-700V2C [manufactured by Seiko Epson Corporation], and is known to be an aqueous ink using a water-soluble dye as a main recording agent. The following evaluation was performed in the same manner as in Example 1. The results are shown in the table.

[0037]

[Example 6] Ink for inkjet printer "BJ"
I-201M ”80 parts by weight of ionomer resin fine particles S
20 weight% of -200 water dispersion (27% of solid content) was added,
Prototype ink (14). "BJI-201M" is a commercially available magenta ink for inkjet printer BJC-600J (manufactured by CANON).
The following evaluation was performed in the same manner as in Example 1. The results are shown in the table.

[0038]

Example 7 Ink for inkjet printer “MJ
IC2 ”80 parts by weight of ionomer resin fine particles S-20
20 wt% of 0 water dispersion (solid content 27%) was added to prepare a trial ink (15). "MJIC2" is an inkjet printer MJ-700V2C [manufactured by Seiko Epson Corporation].
It is a commercially available black ink. The following evaluation was performed in the same manner as in Example 1. The results are shown in the table.

[0039]

As described above, the ink jet recording ink of the present invention is capable of high quality recording images and printing, and has high resistance to nozzle clogging.
Further, it is a product having excellent characteristics that is stable even when it is stored for a long period of time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yozo Yamada 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd.

Claims (8)

[Claims] 1. An inkjet recording ink using a water-soluble dye as a recording agent, which has a specific gravity of 0.9 to 1.0.
5. An ink for inkjet recording, comprising 0.5 to 15% by weight of synthetic resin fine particles having an average particle diameter of 0.2 to 1.0 μm. 2. The specific gravity of the synthetic resin fine particles is 0.93 to
It is in the range of 1.00 and the average particle size is 0.3 to 0.8 μ.
The ink for inkjet recording according to claim 1, which is in a range of m. 3. The ink for ink jet recording according to claim 1, wherein the synthetic resin fine particles are non-swelling with lower alcohol and / or alkylene glycol and / or alkanolamines. 4. The ink jet recording ink according to claim 1, wherein the synthetic resin fine particles are a (co) polymer containing 50% by weight or more of ethylene and / or propylene. 5. The synthetic resin fine particles are methylstyrene 5
The ink for inkjet recording according to claim 1, which is a (co) polymer composed of 0% by weight or more. 6. The ink-jet recording ink according to claim 1, wherein the synthetic resin fine particles are an ethylene / (meth) acrylic acid copolymer. 7. The inkjet recording ink according to claim 1, wherein the synthetic resin fine particles are made of an ionomer resin made of an ethylene / (meth) acrylic acid copolymer and have a Vicat softening point in the range of 40 to 100 ° C. 8. The ink for ink jet recording according to claim 1, wherein the synthetic resin fine particles are obtained by an emulsifying means that does not use an emulsifier.