JP3468309B2 - Ink for inkjet printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output device, and more particularly to an ink for an ink jet printer. 2. Description of the Related Art As output devices of information devices such as computers, dot matrix printers, thermal transfer printers,
There are various methods such as laser printers.
An ink jet method has attracted attention as a method which has a low running cost, has high definition, and is easy to colorize. Conventionally, aqueous dye solutions have been used as inks for ink jet printers.However, when ink ejected from a nozzle adheres to recording paper, the ink bleeds on the recording paper and is smaller than ink particles formed when the ink is ejected. There have been problems with large dots and the water resistance of the recorded image. Conventionally, many ideas have been proposed for such ink-jet inks in order to solve these problems. a) A water-soluble dye is dissolved in a mixed solvent of water and an organic solvent, the concentration of the dye is adjusted to 5% by weight or less, and the additive of the organic solvent is adjusted to a range of 3 to 30% (JP-A-62-124166).
B) Ink containing a specific diether compound added to the ink (Japanese Patent Application Laid-Open No. 62-32159) c) Using a water-soluble direct dye or an acidic dye from which a surface-active substance is removed by an adsorption resin (Japanese Patent Application Laid-Open No. 60-32159) -49070) d) Ink added with dye and emulsion for forming a film
18462) e) Those using emulsion polymerization or dispersion polymerization particles dyed with a dye (Japanese Patent Application Laid-Open No. 3-250069) have been proposed. [0004] The above-mentioned ink (a) ~
(d) reduces the ink bleeding on the recording paper to some extent, but it was impossible to completely prevent the ink bleeding due to the capillary phenomenon on the recording paper fibers. On the other hand, in the above-mentioned method e), bleeding does not occur because dyed polymer particles are used, but the particles obtained by this method have poor stability of the particles and the dye precipitates when left for a long time. It settles down or emerges on the particle surface. Furthermore, since it is difficult to dye at a high density, a sufficient image density cannot be obtained. SUMMARY OF THE INVENTION The present invention provides an ink jet printer capable of eliminating ink bleeding on recording paper and obtaining an extremely good image density. That is, the present invention relates to a particle colored with a dye.
Fine resin particles with a diameter of 0.1 to 1.0 μm
In the ink for an inkjet printer which is an aqueous dispersion obtained by finely dispersing 10 to 50 wt%, the fine resin particles are
20 to 1000 eq / ton
Micro-trees made of polyester resin and contained in fine resin particles
The content of the dye with respect to the fat particles is 2 to 20 wt%,
Add 0.1 to 10% by weight of ethylene glycol or
It is contained serine or polyhydric alcohols, surface tension of the ink is an ink for inkjet printer, which is a 25～40Dyn. The present invention has solved the problem of obtaining a high image density by using polyester which can be easily dyed as fine particles. Further, since the polyester is an emulsion, when it adheres to recording paper, it also has the effect of reducing bleeding. The ink of the present invention has an essential condition that the surface tension of the whole ink is in the range of 25 dyn to 40 dyn. Within this range, water, which is a dispersion medium for the ink, is easily absorbed by the recording paper, and has the effect of extremely reducing ink bleeding. If the surface tension of the ink is less than 25 dyn, dripping of the ink will occur on the print head nozzles, making it difficult to perform good printing. The polyester fine particles used in the present invention are preferably in an emulsion state.
It is less than or equal to 1 micron. Further, the polyester resin used for the polyester fine particles of the present invention comprises a polyvalent carboxylic acid and a polyvalent alcohol. Examples of the polycarboxylic acids used in the polyester resin include, for example, terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, diphenic acid, sulfoterephthalic acid, Aromatic dicarboxylic acids such as sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7 dicarboxylic acid, 5 [4-sulfophenoxy] isophthalic acid, sulfoterephthalic acid, and / or metal salts and ammonium salts thereof;
p-Hydroxybenzoic acid Aromatic oxycarboxylic acid such as p- (hydroxyethoxy) benzoic acid, aliphatic dicarboxylic acid such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, fumaric acid, maleic acid , Itaconic acid, hexahydrophthalic acid, unsaturated aliphatics such as tetrahydrophthalic acid, and the like, and alicyclic dicarboxylic acids and the like.
Examples thereof include trivalent or higher polycarboxylic acids such as trimesic acid and pyromellitic acid. Examples of the polyhydric alcohols used in the polyester resin include aliphatic polyhydric alcohols, alicyclic polyhydric alcohols, and aromatic polyhydric alcohols.
Aliphatic polyhydric alcohols include ethylene glycol
, Propylene glycol, 1,3-propanediol-
2,3-butanediol, 1,4-butanediol
1,5-pentaneddiol, 1,6-hexanediol, neopentyl glycol, diethylene glycol
, Dipropylene glycol, 2,2,4-trimethyl-1,3-pentaneddiol, polyethylene glycol
Examples include aliphatic diols such as toluene, polypropylene glycol and polytetramethylene glycol, and triols and tetraols such as trimethylolethane, trimethylolpropane, glycerin and pentaerthritol. it can. The alicyclic polyhydric alcohols include 1,4-
Cyclohexanediol, 1,4-cyclohexanedimethanol, spiroglycol, hydrogenated bisphenol A, ethylene oxide adducts and hydrogenated bisphenol A adducts of propylene oxide, tricyclodecanediol, Tricyclodecane dimethanol and the like can be exemplified. Examples of aromatic polyvalent alcohols include para-xylene glycol, meta-xylene glycol, ortho-xylene glycol, 1,4-phenylene glycol, and ethylene oxide adduct of 1,4-phenylene glycol. , Bisphenol A, and ethylene oxide adducts and propylene oxide adducts of bisphenol A. Further, as a polyester polyol, ε
-Lactone-based polyester polyols obtained by ring-opening polymerization of lactones such as caprolactone. In addition, a monofunctional monomer may be introduced into the polyester for the purpose of blocking the polar group at the terminal of the polyester polymer. Monofunctional monomers include benzoic acid, chlorobenzoic acid, bromobenzoic acid, parahydroxybenzoic acid, monoammonium sulfobenzoate, monosodium sulfobenzoate, cyclohexylaminocarbonylbenzoic acid, n-dodecylaminocarbonylbenzoate Acid, tert-butylbenzoic acid, naphthalenecarboxylic acid, 4-methylbenzoic acid, 3-methylbenzoic acid, salicylic acid, thiosalicylic acid, phenylacetic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, octanecarboxylic acid, lauric acid, stearyl acid And monocarboxylic acids such as lower alkyl esters thereof, or aliphatic alcohols.
Monoalcohols such as alcohols, aromatic alcohols and alicyclic alcohols can be used. In the present invention, an unsaturated monomer is used as required among these, and other components are appropriately selected depending on the glass transition temperature of the polyester resin, compatibility with the monomer, and the like. As the ionic group to be introduced into the polyester, a mono- or dicarboxylic acid having an alkali metal sulfonate or ammonium sulfonate can be preferably used. , A sulfate group, a phosphate group, a phosphonate group, a phosphinate group or an anionic group such as an ammonium salt or a metal salt thereof, or a cationic group such as a primary to tertiary amine group. You can use a monomer or the like. When an alkali metal carboxylate or ammonium carboxylate is introduced, a carboxyl group is added to the polymer terminal by introducing a polyvalent carboxylic acid such as trimellitic acid into the system at the end of polymerization of the polyester. Then, a method of neutralizing this with ammonia, sodium hydroxide, or the like to exchange the group with a carboxylate group can be used. Further, by containing a mono- or dicarboxylic acid having a sulfonic acid alkali metal base or a sulfonic acid ammonium base, these ionic groups can be introduced into the polyester resin. As salts, ammonium ions, Li, Na,
Salts such as K, Mg, Ca, Cu, Fe and the like are mentioned, and particularly preferred are K salts and Na salts. In the present invention, 5-
It is preferable to use sodium sulfoisophthalic acid or metasodium sulfobenzoic acid. Further, a carboxylate group and a sulfonate group may be used. The following are more specific examples of the polyester resin of the present invention. a) a polyvalent carboxylic acid containing at least 80 mol% of an aromatic monomer, and b) a polyester resin obtained from 0 to 90 mol% of ethylene glycol and 100 to 10 mol% of propylene glycol, or a) A) a polyester resin obtained from a polyvalent carboxylic acid containing at least 80 mol% of an aromatic monomer, and b) 5-80 mol% of 2,3-butanediol and 20-95 mol% of ethylene glycol, or A) polyhydric carboxylic acids containing at least 80 mol% of an aromatic monomer, b) 70-95 mol% of C2 -C4 aliphatic glycols, c) mono- or polyvalent having a tricyclodecane skeleton A) a polyester resin obtained from 5 to 30 mol% of alcohols, or a) a polyvalent carboxylic acid containing at least 80 mol% of an aromatic monomer, and b) an aliphatic glycol of C2 to C4. 70-95 mol%, c) hydroxymethyl A) a polyester resin obtained from 5 to 30 mol% of cyclodecane, or a) a polyvalent carboxylic acid containing at least 80 mol% of an aromatic monomer, and b) an aliphatic glycol of C2 to C4. A polyester resin obtained from 70 to 95 mol%, c) 5 to 30 mol% of tricyclodecane dimethanol, or a) a polycarboxylic acid containing at least 80 mol% of an aromatic monomer; A polyester resin obtained from 70 to 95 mol% of aliphatic glycols having a C4 to C4 content, c) 5 to 30 mol% of mono- or polyvalent alcohols having a cyclohexane skeleton, or a) an aromatic monomer. A) a polyester resin obtained from: a polycarboxylic acid containing at least 80 mol%; b) 70 to 95 mol% of a C2 to C4 aliphatic glycol; c) 5 to 30 mol% of cyclohexanediol; Aromatic monomers A polyester resin obtained from a polyvalent carboxylic acid containing 0 mol% or more, b) 70 to 95 mol% of a C2 to C4 aliphatic glycol, c) 5 to 30 mol% of hydrogenated biphenol, or A) a polycarboxylic acid containing at least 80 mol% of an aromatic monomer; b) 70-95 mol% of a C2 -C4 aliphatic glycol; c) hydrogenated bisphenol A5 A) a polyhydric carboxylic acid containing at least 80 mol% of an aromatic monomer containing 1 to 20 mol% of a mono- or divalent or more carboxylic acid having a naphthalene skeleton, and b) ) 70-100 mol of C2 -C4 aliphatic glycols
%, C) a polyvalent alcohol containing 0 to 30 mol% of an alicyclic monomer.
And polyester resins obtained from the following. Furthermore, shown here, "a) aromatic monomer"
Is preferably terephthalic acid or isophthalic acid. The ratio of terephthalic acid to isophthalic acid is as follows: terephthalic acid content / isophthalic acid content = 90 to 40/10
60 [mol%] is preferable, and terephthalic acid content / isophthalic acid content = 80 to 50/20 to 50 [mol]
%], And more preferably terephthalic acid content / isophthalic acid content = 85-60 / 15-40 [mol%]. When an ionic group-containing monomer is introduced into a polyester resin to give the polyester resin an ionic group, the polyester resin exhibits water dispersibility. As the ionic group-containing monomer, a mono- or dicarboxylic acid having an alkali metal sulfonic acid group or an ammonium sulfonic acid salt described above can be preferably used. Monomer, a sulfate group, a phosphate group, a phosphonate group, a phosphinate group or an anionic group such as an ammonium salt or a metal salt thereof;
A cationic group monomer such as a tertiary or tertiary amine group can be used. When an alkali metal carboxylate or ammonium carboxylate is introduced, a carboxyl group is added to the polymer terminal by introducing a polyvalent carboxylic acid such as trimellitic acid into the system at the end of the polymerization of the polyester, and A method can be used in which this is neutralized with ammonia, sodium hydroxide, or the like, and exchanged with a carboxylate group. The content of these ionic groups including sulfonic acid groups and or groups of a salt thereof, the polyester resin to, 20 to 1000 m eq / 1000 g, preferably 20~500m equivalent / 1000 g, Incidentally preferably 50 ２００200 meq / 1000 g. When the content of the ionic group is less than a predetermined amount, sufficient water dispersibility cannot be obtained. In the present invention, the content of the (colored) fine particles in the ink is 10 to 50 Wt. Is the percent of the range. When the content is 10 Wt. Image density can not be obtained necessary in less than%, content of 50 wt. %, The viscosity of the ink (dispersion) increases, making it more likely that the ink will be difficult to eject from the nozzles. The content of the dye with respect to the resin fine particles is preferably 2 to 20 Wt. % Range. 2Wt. In less than%, no satisfactory image density can not be obtained,
20Wt. When it exceeds percent, the dispersion tends to be unstable. As the dye, "a dye insoluble in water at ordinary temperature" is preferably used. These are generally classified as disperse dyes or oil-soluble dyes. More specific examples are as follows. I. Disperse Yellow
198.C. I. Disperse Yellow 42
・ C. I. Solvent Yellow 162 C.I.
I. Disperse Red 92 C.I. I. Disp
erse Red 60 C.I. I. Solvent Re
d49 · C. I. Disperse Violet 2
6. C. I. Disperse Violet 35 ・
C. I. Disperse Blue 60 C.I. I. D
isperse Blue 49 · C. I. Disper
se Blue 87 · C. I. Solvent Blu
e25.C. I. Solvent Blue 35 ・
C. I. Solvent Blue 38 C.I. I. So
lvent Blue 70 C.I. I. Solvent
Black 3 and the like. These are particularly excellent in light fastness, sublimation fastness, hue and saturation, and are preferable as three primary colors for process colors. In addition, a known dye or pigment may be used in combination for fine adjustment of hue. The average particle diameter of the fine particle dispersion in the present invention is essential to be 1.0 μm or less, preferably 0.5 μm. It is as follows. When the particle system of the fine particle dispersion exceeds this range, the dispersion stability may be deteriorated.
The average particle size is preferably at least 0.1 μm or more. When the particle system of the fine particle dispersion exceeds this range, bleeding of the ink may be increased. A fine particle dispersion of such a polyester resin can be obtained by the method described below. That is, when the polyester resin contains an ionic group, the polyester resin in the present invention exhibits water dispersibility. The water dispersibility means a state generally called an emulsion or a colloidal dispersion. The ionic group dissociates in the aqueous medium to form an electric double layer at the interface between the polyester resin and water. When the polyester resin is present in the aqueous system as fine microparticles, the action of the electric double layer causes electrostatic repulsion between the microparticles, and the microparticles are stably dispersed in the aqueous system. The aqueous dispersion of the ionic group-containing polyester resin is prepared by mixing the ionic group-containing polyester resin and the water-soluble organic compound in advance and then adding water, or by mixing the ionic group-containing polyester resin with the water-soluble organic compound and water. Can be obtained by a method of mixing and heating all at once. At that time, a surfactant or the like may be used in combination. Ethanol, isopropanol, and water-soluble organic compounds
Butanol, ethylene glycol, propylene glycol
, Methyl cellosolve, ethyl cellosolve, butyl cellosolve, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane and the like. The water-soluble organic compound is preferably one which can be removed by azeotropic distillation after dispersing the ionic group-containing polyester resin in water. The polyester resin of the present invention has good light fastness even when finely divided with a dye. As a method for incorporating the dye into the polyester resin, a high-temperature dispersion dyeing method can be used. The method of directly kneading the dye precursor into the resin is not a preferable method in consideration of the damage of the dye by heating. Since the polyester resin of the present invention shows good stable dispersibility in water due to the action of the ionic group, high-density dyeing is possible while maintaining the particle shape. Further, at the time of emulsification, a dye may be added when the polyester resin is dissolved with a solvent. The ink for an ink jet printer of the present invention contains 10 to 50% by weight of fine polyester particles dispersed in water.
In addition, the ink for an inkjet printer of the present invention may contain, if necessary, a surfactant or a polymer dispersion stabilizer, which is a dispersant or a dispersion stabilizing aid, in addition to the fine polyester particles. In order to enhance the wettability of the particles, the addition of ethylene glycol, glycerine, various polyhydric alcohols. Further, various chelating agents may be added to block metal ions mixed in the ink. Further, in order to improve the storage stability of the ink, various germicides, fungicides, ultraviolet absorbers, antioxidants and the like may be added. Example 1 (Synthesis of polyester resin) In an autoclave equipped with a thermometer and a stirrer, 140 parts by weight of dimethyl terephthalate, 140 parts by weight of dimethyl isophthalate, 5 sodium Sulfoisophthalic acid dimethyl ester 1
1 part by weight, 102 parts by weight of ethylene glycol and 172 parts by weight of neopentyl glycol were charged and heated at 180 to 230 ° C. for 120 minutes to carry out a transesterification reaction. Then, the temperature of the reaction system was raised to 240 ° C., and the reaction was continued at a system pressure of 1 to 10 mmHg for 60 minutes, thereby obtaining a copolymerized polyester resin. Next, 150 parts by weight of the obtained polyester resin, 150 parts by weight of methyl ethyl ketone, 150 parts by weight of tetrahydrofuran, dye C.I. I. 15 parts by weight of a solvent cake of Solvent Blue 70 were dissolved at 80 ° C., and then 600 parts of water at 75 ° C. were added to obtain an aqueous microdispersion of a copolymerized polyester resin having a particle diameter of about 0.15 μm. Further, the obtained aqueous microdispersion was placed in a distillation flask and distilled until the fraction temperature reached 100 ° C. After cooling, water was added to adjust the solids concentration to 20%. Since the obtained aqueous microdispersion has a surface tension of about 60 dyn, ethylene glycol is further added to reduce the surface tension so that the ethylene glycol concentration becomes 10% of water as a dispersion medium. I made it. The measured surface tension was 40 dyn. The aqueous micro-dispersion thus obtained is applied to an ink jet printer (IO-735 manufactured by SHARP).
X) was used as the ink. The paper used was not processed for inkjet.
As a result, when the ink according to the present invention was used, there was no bleeding of the ink. The density of the obtained image was extremely high, and the image was clear. In addition, the produced aqueous microdispersion showed extremely good stability without generation of a precipitate or precipitation of a dye even when left at room temperature for 3 months or more. Comparative Example 1 As a comparative example, a dispersion made of styrene was prepared. A styrene polymer was prepared by emulsion polymerization to obtain a monodisperse having an average particle size of about 0.1 μm. Next, the obtained styrene dispersion was treated in the same manner as in Example 1 with C.I. I. Solvent
Blue 70 was dyed with a dye solution dispersed with a surfactant (Mignol 802, manufactured by YAS Co., Ltd.). The temperature at this time was 130 ° C., and the dyeing time was 2 hours. The dispersion thus produced had a low microconcentration and the stability of the dispersion was poor. When the dispersion was allowed to stand at room temperature for 3 months or more, precipitation of dye was observed. Comparative Example 2 As a comparative example, bleeding of the ink was observed using a water-soluble dye commonly used in ink-jet inks. The water-soluble dye used was C.I. I. Acid Blue 1 was dissolved in water to obtain an ink. As a result, when the special paper was used, it was good, but when the plain paper was used, it was much different from the present invention, and it was greatly blurred. Light resistance was also compared. Each of the printed inks was UV fade meter (carbon arc) at 63 ° C for 20 minutes.
The color difference before and after the time irradiation was measured. As a result, the ink of the present invention had ΔE of 1 to 3, whereas the ink of the water-soluble dye had a large color fade of ΔE of 8 to 40. [0026] To study the difference in Comparative Example 3 the surface tension, the ink was added ink B (surface tension 65 dyn) and ethylene glycol was not added ethylene glycol aqueous microdispersion body fabricated in Example 1 EG (surface tension of 40 dyn) was prepared. Each ink is a printer IO manufactured by SHARP
Printed at -735X. At this time, the B and EB inks are
When dots were alternately printed, and the degree of ink bleeding at the boundary was observed, the ink EG to which ethylene glycol was added to reduce the surface tension showed a small ink bleed. In contrast, the ink B having a high surface tension without adding ethylene glycol mixed with the ink EG at the boundary. It has been found that the ink having the specific surface tension containing the fine resin particles of the present invention can provide a clear image with less bleeding.

Continuation of front page (56) References JP-A-58-45272 (JP, A) JP-A-62-95366 (JP, A) JP-A-7-97540 (JP, A) JP-A-7-102200 (JP) JP-A-7-133455 (JP, A) JP-A-7-150098 (JP, A) JP-A-7-196965 (JP, A) Patent 3345959 (JP, B2) (58) Int.Cl. ⁷ , DB name) C09D 11/00-11/20

Claims (1)

(57) [Claims] [Claim 1] The particle diameter colored with a dye is 0.1 to 1.0.
μm fine resin particles are finely dispersed in an aqueous medium in an amount of 10 to 50% by weight.
Polyester resin containing q / ton ionic group
And dyes the fine resin particles in the fine resin particles.
The content of the filler is 2 to 20 wt%, and the aqueous dispersion is 0.1 to 10 watts.
t% ethylene glycol or glycerin or polyvalent
Contains alcohol, and the surface tension of the ink is 25 ~
An ink for an ink jet printer, which is 40dyn.