JP2001353962A - Ink jet image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method and an ink jet image recording liquid, with which an ink jet recorded image excellent in image quality and image preservability is formed. SOLUTION: In the ink jet image forming method, in which an image is formed with an ink having at least water, an ink solvent and pigments on the surface of an ink jet recording medium produced by forming a void layer including fine inorganic particles on a support, the ink including at least one among compounds represented by formula (1), A(groups including a hydrophilic substituent)-B(hydrophobic groups), as the ink solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet image forming method, and more particularly, to an ink jet recording medium containing inorganic fine particles and having a void layer formed thereon, and an ink jet image forming method using an ink containing at least water, an ink solvent and a pigment. The present invention relates to an image forming method having high reflection density, excellent gloss and image storability, and excellent image quality.

[0002]

2. Description of the Related Art An ink jet recording method is capable of recording a high-definition image with a relatively simple apparatus, and is rapidly developing in various fields. 2. Description of the Related Art Printers adopting an ink jet recording method are manufactured in a wide range of fields, and the types of inks and recording media are also diversified according to the intended use.

In recent years, there has been developed an image forming method using an ink-jet printer or an ink / recording medium which promotes a so-called photographic image quality for the purpose of forming an image requiring a high image quality such as a landscape image or a portrait image. . Ink jet images formed by these image forming methods are extremely excellent in image quality, and have achieved image quality equivalent to or better than images formed by image forming methods using conventional silver halide photographic materials. However, these ink-jet image forming methods use a dye ink, and in image storability such as light fastness and bleeding, there is still a drawback that the storability of an image formed by a silver halide photographic light-sensitive material is not far. Had.

In order to improve the image storability, pigment inks using a pigment having excellent storability as a colorant have been developed. However, when an ink-jet image is formed using this pigment ink, there is a disadvantage that the image quality is inferior, though the light resistance and the bleeding are excellent.

On the other hand, in order to achieve so-called photographic quality,
An ink jet printer using two same color inks having different color material densities has been developed. In such a printer, the granularity can be reduced by using a large amount of low-concentration ink, but on the other hand, the ink absorption capacity and drying capacity of the recording medium are problematic. Since it cannot be absorbed completely, color mixing, ink overflow and the like become problems.

In recent years, an ink jet recording medium containing an inorganic fine particle and having a void layer formed therein has been developed for the purpose of high drying properties. This recording medium has two features: that the ink is rapidly absorbed into the gap by capillary action, and that the layer has a large gap inside the layer so that a large amount of ink can be held inside. Thus, even an ink jet printer using two same color inks having different color material densities for the purpose of achieving the above-described photographic image quality has sufficient ink absorption capacity and drying ability.

However, when an ink jet recording medium containing the inorganic fine particles and having a void layer is used,
It has become clear that the diameter of the dots on the recording medium is smaller than the diameter of the dots when the dye ink is used, and that the image quality is significantly deteriorated. Specifically, compared with images formed by silver halide photographic materials, there are drawbacks such as a low reflection density, low gloss, and banding phenomena that make the stripes in the scanning direction of ink jet recording clear. And the image quality was inferior.

In the ink jet image forming method,
After the droplets discharged from the ink jet head land on the surface of the recording medium, they penetrate and diffuse in the depth direction and the horizontal direction of the recording medium, thereby forming dots having an appropriate diameter. Here, in the ink jet recording medium in which the gap layer is formed, the diameter tends to be small because the ink quickly penetrates in the depth direction through the gap.
In particular, when a pigment ink is used, a solvent portion, such as water or an organic solvent, which forms the ink quickly permeates in the depth direction before the droplets diffuse in the horizontal direction on the surface of the recording medium. In particular, in a recording medium in which a void layer is formed by inorganic fine particles, since pigment particles are unlikely to enter the inside of a recording medium like plain paper or coated paper, the pigment particles are quickly fixed together, and the diameter of the dot is reduced. It has the disadvantage that it is significantly smaller than when a dye ink is used.
For this reason, defects such as a decrease in reflection density, a decrease in gloss, and the occurrence of a banding phenomenon become remarkable, and a defect that image quality is significantly deteriorated is developed.

Japanese Patent Publication No. 7-84089 discloses an ink-jet ink characterized in that the composition ratio of the ink solvent is 1 to 45%. This technique aims to improve the fixability and feathering of the ink on an ink jet recording medium by optimizing the ratio of the ink solvent in the ink.

However, it has been found that when the composition ratio of the ink solvent is low, the pigment particles tend to adhere to each other. In particular, this tendency is remarkable in a recording medium in which a void layer is formed by inorganic fine particles, and a problem has been pointed out that the diameter of a dot is further reduced.

JP-A-8-60050 discloses pigments,
An ink containing a polymeric dispersant and a humectant having a specific structure is disclosed. In recent years, on-demand type ink jet printers have been used very frequently for two reasons, that is, waste of energy is small because ink droplets are ejected only when necessary, and that the structure is simple. However, in this on-demand type ink jet printer, especially in a low humidity environment, the ink viscosity in the vicinity of the discharge port increases due to evaporation of water at the discharge port that is not capped or discharged for a certain period of time, and normal discharge is performed. Is no longer performed, which is a so-called decap resistance. Although this technique achieves the improvement of the decap resistance, it has not been able to eliminate the deterioration of image quality due to a small dot diameter which is remarkable in a combination of a pigment ink and a recording medium having a void structure.

As a technique for improving the deterioration of the image quality when using the pigment ink, for example, Japanese Patent Application Laid-Open No. Hei 6-88048 discloses a technique in which the concentration of a surfactant is larger than the critical micelle concentration for pure water, An image forming method for making the density lower than the micelle density is disclosed. However, this method is a technique aimed at improving the image quality when so-called plain paper is used, and is characterized by improving the permeation speed into a recording medium. Therefore, when using an inkjet recording medium having a void layer which is a problem in the present application, the diameter of the dot becomes smaller conversely,
There is a disadvantage that the image quality is further deteriorated. Japanese Patent Application Laid-Open No. 11-240145 includes a self-dispersing pigment and an anionic dye, and further includes a Ka in the Bristow method.
There is disclosed an image forming method using ink, wherein the value is less than 1 ml · m ⁻² · msec ^-1/2 .
This technique has succeeded in giving a large dot diameter by adjusting the ink absorption speed to equalize the spread of the dots in the dye portion and the pigment portion. However, even if this technique is used, the penetration speed is high when an ink jet recording medium having a void layer is used,
As a result, it has been found that the dot diameter is not sufficiently enlarged, and that the image quality cannot be improved.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method for forming an ink jet recorded image having excellent image quality and image storability.

[0014]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventors have found an image forming method capable of achieving the object by the following image forming method.

1. In an inkjet image forming method for forming an image using an ink having at least water, an ink solvent and a pigment on the surface of an inkjet recording medium containing inorganic fine particles and a void layer formed on a support, the ink solvent has the general formula An inkjet image forming method using an ink containing at least one of the compounds represented by (1).

2. 2. The method according to claim 1, wherein the compound represented by the general formula (1) accounts for 50% or more of the total ink solvent.

3. 2. The ink-jet image according to the above item 1, wherein the proportion of the ink solvent contained in the ink exceeds 45%, and a part or all of the ink solvent is a compound represented by the general formula (1). Forming method.

4. Wherein the hydrophilic substituent of A is a hydroxy group, and the hydrophobic group of B is an aliphatic or aromatic hydrocarbon group having 3 to 10 carbon atoms.
The inkjet image forming method according to any one of the above items.

5. A polyhydric alcohol ether derivative wherein at least one hydroxy group is unsubstituted and at least one hydroxy group is substituted by an aliphatic or aromatic hydrocarbon group having 4 to 8 carbon atoms, or a polyhydric alcohol ether derivative having 4 to 8 carbon atoms 5. The inkjet image forming method according to the above item 4, wherein the aliphatic 1,2-diol is

6. A polyhydric alcohol ether derivative or an aliphatic 1,2-diol having 4 to 8 carbon atoms is ethylene glycol monobutyl ether (butyl cellosolve);
6. The inkjet image forming method according to the above item 5, wherein the compound is at least one compound selected from diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, 1,2-hexanediol, and 1,2-pentanediol.

7. 6. The inkjet image forming method according to the above item 5, wherein the polyhydric alcohol ether derivative or the aliphatic 1,2-diol having 4 to 8 carbon atoms is triethylene glycol monobutyl ether or 1,2-hexanediol.

Hereinafter, the present invention will be described in detail. In the colorant receiving layer of the inkjet recording material according to the present invention,
It is necessary that a void layer having an ink retaining ability is formed, and the void layer is formed mainly by soft aggregation of a hydrophilic binder and inorganic fine particles.

Conventionally, various methods for forming voids in a film have been known. For example, a uniform coating solution containing two or more polymers is coated on a support, and these polymers are mutually bonded in a drying process. A method of forming voids by phase separation,
A coating liquid containing solid fine particles and a hydrophilic or hydrophobic binder is coated on a support, dried, and then the ink jet recording paper is immersed in a liquid containing water or a suitable organic solvent to dissolve the solid fine particles to form voids. A method of forming a void in a film by applying a coating solution containing a compound having a property of foaming at the time of film formation and then drying the compound in a drying process after coating, a coating containing porous solid fine particles and a hydrophilic binder. A method in which a liquid is applied on a support to form voids in and between porous fine particles, solid fine particles and / or fine particles having a volume of at least approximately equal to (preferably at least 1.0 times) the volume of the hydrophilic binder A method of forming a gap between solid fine particles by applying a coating solution containing an oil droplet and a hydrophilic binder on a support, and the like, are known in the present invention. It is characterized by being formed by the inclusion of various inorganic solid fine particles.

Examples of the inorganic fine particles used for the above purpose include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide and zinc hydroxide. , Zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, hydroxylated Examples thereof include white inorganic pigments such as magnesium.

The average particle diameter of the inorganic fine particles is determined by observing the particles themselves or the particles that have appeared on the cross section or surface of the void layer with an electron microscope, obtaining the particle diameter of 1,000 arbitrary particles, and calculating the simple average value ( (Number average). Here, the particle diameter of each particle is represented by a diameter assuming a circle equal to its projected area.

From the viewpoints of high density image formation, clear image recording and low-cost production, it is preferable to use solid fine particles selected from silica and alumina or alumina hydrate. Is more preferred.

As the silica, silica or colloidal silica synthesized by an ordinary wet method, silica synthesized by a gas phase method, or the like is preferably used. Colloidal silica or colloidal silica is particularly preferably used in the present invention. It is a fine particle silica synthesized by a gas phase method.
Among them, fine particle silica synthesized by a gas phase method is preferable because not only high porosity can be obtained but also coarse aggregates are hardly formed when added to a cationic polymer used for fixing a dye. The alumina or alumina hydrate may be crystalline or amorphous, and may have any shape such as irregular particles, spherical particles, and acicular particles.

The fine particles of the present invention are preferably in a state where the fine particle dispersion before being mixed with the cationic polymer is dispersed to primary particles.

In order to obtain the effects of the present invention, the inorganic fine particles on the support preferably have a particle size of 100 nm or less. For example, in the case of the above-mentioned fumed silica, the average particle diameter of the particles dispersed in the state of primary particles (the particle diameter in the state of the dispersion before coating) is preferably 100 nm or less, more preferably 4 nm or less. ~ 50 nm, most preferably 4 ~
20 nm.

As the most preferably used silica synthesized by a gas phase method having an average primary particle diameter of 4 to 20 nm, for example, Aerosil manufactured by Nippon Aerosil Co., Ltd. is commercially available. The vapor-phase-process fine-particle silica can be relatively easily dispersed into primary particles by being easily suction-dispersed in water using, for example, a jet stream inductor mixer manufactured by Mitamura Riken Kogyo KK.

Examples of the hydrophilic binder according to the present invention include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, color ginnan (κ, ι, λ, etc.),
Agar, pullulan, water-soluble polyvinyl butyral, hydroxyethyl cellulose, carboxymethyl cellulose and the like can be mentioned.

These water-soluble binders can be used in combination of two or more. The water-soluble binder preferably used in the present invention is polyvinyl alcohol.

The polyvinyl alcohol preferably used in the present invention includes, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, polyvinyl alcohol having a cation-modified terminal or anion-modified polyvinyl alcohol having an anionic group. Of modified polyvinyl alcohol.

The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 1,000 or more, and particularly has an average degree of polymerization of 1,500 to 5,
000 are preferably used. Saponification degree is 70 ~
100% is preferable, and 80 to 99.5% is particularly preferable.

As the cation-modified polyvinyl alcohol, for example, as described in JP-A-61-10483, primary to tertiary amino groups and quaternary ammonium groups are used as the main chain or side chain of the polyvinyl alcohol. Polyvinyl alcohol contained therein, which is obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl). Ammonium chloride, N-vinylimidazole, N-vinyl-2-methylimidazole, N
-(3-dimethylaminopropyl) methacrylamide,
Hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1,1-dimethyl-3-
Dimethylaminopropyl) acrylamide and the like.

The proportion of the cation-modified group-containing monomer in the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, based on vinyl acetate.

The anion-modified polyvinyl alcohol is, for example, a polyvinyl alcohol having an anionic group as described in JP-A-1-2060888, JP-A-61-237681 and JP-A-63-307979.
Copolymer of vinyl alcohol and a vinyl compound having a water-soluble group as described in
Modified polyvinyl alcohol having a water-soluble group as described in JP-A-285265.

The nonionic modified polyvinyl alcohol includes, for example, a polyvinyl alcohol derivative having a polyalkylene oxide group added to a part of vinyl alcohol as described in JP-A-7-9758.
A block copolymer of a vinyl compound having a hydrophobic group and vinyl alcohol described in JP-A-8-25795 is exemplified.

Two or more kinds of polyvinyl alcohols having different degrees of polymerization and types of modification can be used in combination.

The amount of the inorganic fine particles used in the color material receiving layer greatly depends on the required ink absorption capacity, the porosity of the void layer, the type of the inorganic fine particles, and the type of the water-soluble binder. It is 5 to 30 g, preferably 10 to 25 g per m ² .

The ratio of the inorganic fine particles to the water-soluble binder used in the colorant receiving layer is usually from 2: 1 to 20: 1, and particularly preferably from 3: 1 to 10: 1.

The water-soluble binder is preferably hardened with a hardener in the ink jet recording paper of the present invention in order to obtain excellent gloss and high porosity without deteriorating the brittleness of the film.

The hardener is generally a compound having a group capable of reacting with the water-soluble binder or a compound which promotes the reaction between different groups of the water-soluble binder. It is appropriately selected and used depending on the situation.

Specific examples of hardeners include, for example, epoxy hardeners (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N , N-diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc., aldehyde hardeners (formaldehyde, glyoxal, etc.), active halogen hardeners (2,4-dichloro-4-) Hydroxy-1,3,5-s-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-)
s-triazine, bisvinylsulfonylmethyl ether, etc.), boric acid and its salts, borax, aluminum alum and the like.

When polyvinyl alcohol and / or cation-modified polyvinyl alcohol is used as a particularly preferred water-soluble binder, it is preferable to use a hardener selected from boric acid and salts thereof or an epoxy hardener.

The most preferred hardener is a hardener selected from boric acid and its salts. In the present invention, the boric acid or a salt thereof refers to an oxyacid having a boron atom as a central atom and a salt thereof, and specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, octanoic acid And their salts.

The amount of the hardener used varies depending on the type of the water-soluble binder, the type of the hardener, the type of the inorganic fine particles, the ratio to the water-soluble binder, and the like. Is 10-3
00 mg.

The hardener may be added to the aqueous coating solution for forming the colorant receiving layer of the present invention when the aqueous coating solution is applied, or a coating solution containing the hardener in advance may be added. The aqueous coating solution for forming a colorant receiving layer of the present invention may be applied onto the coated support. Further, the aqueous coating solution for forming a colorant receiving layer of the present invention (containing no hardener) can be supplied by coating and drying, followed by overcoating with a hardener solution. From the viewpoint of production efficiency, preferably, a method in which a hardener is added to the aqueous coating solution for forming a colorant receiving layer of the present invention and coating is performed.

The ink-jet recording material according to the present invention may contain a cationic polymer for the purpose of improving the water resistance of the obtained image. The cationic polymer to be used can be used without any particular limitation. Particularly preferred ones have an average molecular weight of 2,000 to 100,000.
belongs to.

The cationic polymer is preferably a polymer having a quaternary ammonium salt group, particularly preferably a homopolymer of a monomer having a quaternary ammonium salt group or one or more other copolymerizable monomers. Is a copolymer of The cationic water-soluble polymer having a quaternary ammonium base in the molecule is used in an amount of usually 0.1 to 10 g, preferably 0.2 to 5 g per 1 m ^{2 of} the ink jet recording paper.

The total amount of voids (void volume) in the void layer
Is preferably 20 ml or more per 1 m ² of recording paper. When the void volume is less than 20 ml / m ² , the ink absorption is good when the amount of ink at the time of printing is small, but when the amount of ink is large, the ink is not completely absorbed and the image quality is deteriorated or the drying property is deteriorated. Problems such as delay are likely to occur.

The upper limit of the void volume is not particularly limited, but it is preferable that the thickness of the void layer be approximately 50 μm or less so as not to deteriorate physical properties of the film such as cracks.

In the void layer having an ink retaining ability, the void volume with respect to the solid content volume is called a void ratio. In the present invention, it is preferable to set the porosity to 50% or more because the void can be efficiently formed without unnecessarily increasing the film thickness.

Examples of the support according to the present invention include supports conventionally used for ink jet recording media, for example, paper supports such as plain paper, art paper, coated paper and cast-coated paper, plastic supports, and the like. A paper support coated on both sides with a polyolefin, or a composite support in which these are laminated can be used.

Prior to the application of the void layer, the support is preferably subjected to a corona discharge treatment or an undercoat treatment for the purpose of increasing the adhesive strength between the support and the void layer. Furthermore, the recording paper of the present invention does not necessarily need to be colorless, and may be a colored recording paper.

In the ink jet recording paper of the present invention, the use of a paper support in which both sides of the base paper support are laminated with polyethylene is particularly preferable since the recorded image is close to the photographic quality and a high quality image can be obtained at low cost. preferable.
Such a paper support laminated with polyethylene is described below.

The base paper used for the paper support is made of wood pulp as a main material, and if necessary, is made of synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester in addition to wood pulp. As wood pulp, LBKP, LBSP, NBKP, NBSP, LDP, N
Any of DP, LUKP and NUKP can be used, but LBKP, NBSP, LBSP, N
It is preferable to use more DP and LDP. However,
The ratio of LBSP and / or LDP is 10% or more, 70%
The following is preferred.

As the pulp, a chemical pulp containing a small amount of impurities (sulfate pulp or sulfite pulp) is preferably used, and pulp having improved whiteness by a bleaching treatment is also useful.

In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, starch, polyacrylamide,
Paper strength enhancers such as polyvinyl alcohol, fluorescent whitening agents, water retention agents such as polyethylene glycols, dispersants, and softening agents such as quaternary ammonium can be added as appropriate.

The pulp used for papermaking has a freeness of CSF
The fiber length after beating is preferably 30 to 70%, and the sum of the remaining 24 mesh and the remaining 42 mesh specified in JIS P8207 is preferably 30 to 70%. In addition, it is preferable that the 4 mesh residue is 20% or less.

The basis weight of the base paper is preferably 30 to 250 g, particularly preferably 50 to 200 g. Base paper thickness is 40
２５０250 μm is preferred.

The base paper may be calendered at the papermaking stage or after the papermaking to provide high smoothness. The base paper density is generally 0.7 to 1.2 g / m ² (JIS P8118). Further, the rigidity of the base paper is preferably from 20 to 200 g under the conditions specified in JIS P8143.

A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, the same sizing agent as can be added to the base paper can be used.

The pH of the base paper is preferably 5 to 9 when measured by the hot water extraction method specified in JIS P8113.

The polyethylene covering the front and back surfaces of the base paper is mainly composed of low-density polyethylene (LDPE) and / or
Alternatively, high-density polyethylene (HDPE), but other LLDPE, polypropylene, or the like may be partially used.

In particular, the polyethylene layer on the side of the void layer is preferably one in which rutile or anatase type titanium oxide is added to polyethylene to improve opacity and whiteness as widely used in photographic printing paper. The content of titanium oxide is usually 3 to 20%, preferably 4 to 13% based on polyethylene.

The polyethylene-coated paper may be used as a glossy paper, or may be subjected to a so-called embossing process when the polyethylene is melt-extruded onto the base paper surface to carry out a matting process or a silk-like process which can be obtained with ordinary photographic printing paper. Those having a surface can also be used in the present invention.

The amount of polyethylene used on the front and back of the base paper is selected so as to optimize the curl under low and high humidity conditions after the provision of the void layer and the back layer. 20-40 μm, 10-30 on the back layer side
It is in the range of μm.

Further, the above-mentioned polyethylene-coated paper support preferably has the following characteristics.

1. Tensile strength: strength specified in JIS P8113, 2-30 kg in the vertical direction and 1 in the horizontal direction
20kg 2. 2. The tear strength is 10 to 200 g in the vertical direction and 20 to 200 g in the horizontal direction according to the method defined by JIS P8116. Compression modulus ≧ 98.1 MPa 4. Surface Beck smoothness: 20 seconds or more is preferable as a glossy surface under the conditions specified in JIS P8119, but may be less than this for so-called molded products. 5. Surface roughness: The surface roughness specified in JIS B0601 has a maximum height of 10 μm or less per 2.5 mm of reference length. 6. Opacity: 80% or more, particularly preferably 85 to 98%, as measured by the method specified in JIS P8138. Whiteness: L ^* , a ^* , specified in JIS Z8729
b ^* is L ^* = 80 to 95, a ^* = − 3 to +5, b ^* = − 6 to
+2 8. Surface glossiness: 60 specified in JIS Z8741
Degree of specular gloss is 10 to 95% 9. Clark stiffness: Clark stiffness in the conveying direction of the recording sheet is 50~300cm ^2/100 support 10. Water content of the middle paper: usually 2 to 100% based on the middle paper,
Preferably 2-6%.

The method of applying various hydrophilic layers, such as a void layer and an undercoat layer, of the recording material of the present invention, which are appropriately provided as necessary, onto a support can be appropriately selected from known methods. A preferred method is obtained by applying a coating solution constituting each layer on a support and drying the coating solution. In this case, two or more layers can be applied simultaneously, and in particular, simultaneous application in which all the hydrophilic binder layers need only be applied once is preferable.

Examples of the coating method include a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method and an extrusion coating method using a hopper described in US Pat. No. 2,681,294. It is preferably used.

In the present invention, an ink containing at least water, an ink solvent, a surfactant, and a pigment is used.

Here, it is preferable to use the compound represented by the general formula (1) as the ink solvent.

In the formula, the group represented by A is a group containing a hydrophilic substituent. Examples of the hydrophilic substituent include a hydroxy group, a carboxyl group, a sulfoxide group, a sulfone group, a sulfonic acid group, and a 2-keto-group. And a 1-pyrrolidinyl group.
Among them, a hydroxy group is preferred.

B represents a hydrophobic group, preferably an aliphatic or aromatic hydrocarbon group having 3 to 10 carbon atoms.
Further, B is preferably an aliphatic group having 4 to 8 carbon atoms.

The compound represented by the general formula (1) has a structure similar to that of a general surfactant, but preferably does not have a strong surfactant action such as a surfactant. . General surfactants have the characteristic of forming micelles at low concentrations in aqueous solutions. It is preferable that the compound represented by the general formula (1) of the present invention does not have such micelle-forming ability. This is because when the surfactant has a strong surface activity, the interaction between the molecules is strong, and when the concentration exceeds 1%, the viscosity of the ink is remarkably increased.

Among the compounds represented by the above general formula (1), preferable examples include polyhydric alcohol ether derivatives and aliphatic 1,2-diols having 4 to 8 carbon atoms, and ethylene glycol monobutyl ether (butyl cellosolve) is preferable. ), Diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monophenyl ether, 1,2-hexanediol, or 1,2-pentanediol. More preferred is triethylene glycol monobutyl ether or 1,2-hexanediol.

In the present invention, in addition to the preferred ink solvents described above, other ink solvents can be used. Specific examples of such ink solvents include alcohols (eg, methanol, ethanol, propanol). , Isopropanol, butanol, isobutanol,
Secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc., polyhydric alcohols (eg, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene) Glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), polyhydric alcohol ethers (for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, Propylene glycol No methyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether, etc., amines (for example, ethanolamine, diethanolamine, triethanolamine, N -Methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc., amides (for example, formamide) , N, N-dimethylformamide, N, N-dimethyl Acetamide, etc.), heterocycles (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides (eg, dimethyl sulfoxide), Examples include sulfones (eg, sulfolane), sulfonates (eg, 1-butanesulfonic acid sodium salt), urea, acetonitrile, acetone, and the like.

The ink solvent used in the present invention is:
The compound represented by the general formula (1)
It is necessary to use 0% or more in order to improve the image quality by expanding the decap resistance and the dot diameter. The decap resistance can be improved by increasing the amount of the ink solvent, and practical problems can be reduced by increasing the composition ratio of the ink solvent in the ink to more than 45%. However, in order to increase the dot diameter and improve the image quality, it is necessary to include the ink solvent represented by the general formula (1).

These ink solvents may be used alone or in combination. In the present invention, the ink may contain a surfactant as needed. Surfactants preferably used in the ink of the present invention include anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, and fatty acid salts, polyoxyethylene alkyl ethers, and polyoxyethylene alkyl allyl ethers. And acetylene glycols, nonionic surfactants such as polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. In particular, an anionic surfactant and a nonionic surfactant can be preferably used.

As the pigment that can be used in the present invention, conventionally known organic and inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments,
Polycyclic pigments such as dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthaloni pigments, dye lakes such as basic dye lakes and acid dye lakes, nitro pigments, nitroso pigments, aniline black, daylight fluorescent Organic pigments such as pigments and inorganic pigments such as carbon black are exemplified.

Specific examples of the organic pigment are shown below. Pigments for magenta or red include C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I.
I. Pigment Red 7, C.I. I. Pigment Red 1
5, C.I. I. Pigment Red 16, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53:
1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 12
3, C.I. I. Pigment Red 139, C.I. I. Pigment red 144, C.I. I. Pigment Red 149,
C. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I.
I. Pigment Red 222 and the like.

Examples of pigments for orange or yellow include C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43, C.I. I. Pigment Yellow 12,
C. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I.
I. Pigment Yellow 17, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, C.I. I.
Pigment Yellow 138 and the like.

The pigments for green or cyan include:
C. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3,
C. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.

In the present invention, it is desirable to use an ink set composed of at least two same-color inks having different densities in at least one color. In two or more colors, it is more preferable to use an ink set composed of at least two same-color inks having different densities, and in three or more colors, it is more preferable to use an ink set composed of at least two same-color inks having different densities. preferable.

This is because the use of low-density ink reduces the graininess and makes it possible to form a high-quality image without so-called “graininess”. for that reason,
It is preferable to use at least two inks having different densities in magenta ink or cyan ink having high human visibility.

The density ratio of the ink sets having different densities may be an arbitrary value. However, in order to perform smooth gradation reproduction, the ratio of the high density ink to the low density ink [(the density of the low density ink) （ (Density of high density ink)] is 0.1 to
It is preferably between 1.0, more preferably between 0.2 and 0.5, and particularly preferably between 0.25 and 0.4.

In the present invention, a pigment dispersant may be used as necessary. Examples of the pigment dispersant that can be used include the above-mentioned surfactants, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, alkyl sulfonates, and the like. Phosphates,
Activators such as glycerin esters, sorbitan esters, polyoxyethylene fatty acid amides, amine oxides, or styrene, styrene derivatives, vinylnaphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, Examples include block copolymers, random copolymers, and salts thereof comprising two or more monomers selected from fumaric acid and fumaric acid derivatives.

As a method for dispersing the pigment, various methods such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker can be used.

It is also preferable to use a centrifugal separator or a filter for the purpose of removing coarse particles of the pigment dispersion of the present invention.

The average particle size of the pigment dispersion used in the ink of the present invention is preferably from 10 to 200 nm, more preferably from 10 to 200 nm.
-150 nm is more preferable, and 10-100 nm is still more preferable. If the average particle size of the pigment dispersion exceeds 150 nm, the glossiness of an image recorded on a glossy medium deteriorates, and the transparency of an image recorded on a transparency medium significantly deteriorates. Further, when the average particle size of the pigment dispersion is less than 10 nm, the stability of the pigment dispersion tends to deteriorate, and the storage stability of the ink tends to deteriorate.

The particle size of the pigment dispersion can be measured by a commercially available particle size measuring device using a light scattering method, an electrophoresis method, a laser Doppler method or the like. In addition, it is also possible to obtain a particle image using a transmission electron microscope on at least 100 particles or more, and to perform a statistical process on the image using image analysis software such as Image-Pro (manufactured by Media Cybernetics). It is possible.

The ink according to the present invention may contain a latex. In the present invention, the latex refers to polymer particles dispersed in a medium. Examples of polymer types include styrene-butadiene copolymer, polystyrene, acrylonitrile-butadiene copolymer, acrylate copolymer, polyurethane, and silicone-
There are acrylic copolymers and acrylic-modified fluororesins, among which acrylic esters, polyurethanes and silicone-acrylic copolymers are preferred.

As an emulsifier used for the production of latex, a low molecular weight surfactant is generally used. Among them, a high molecular weight surfactant (for example, a solubilizing group is graft-bonded to a polymer) Type or a block polymer type in which a portion having a solubilizing group and an insoluble portion are linked) as an emulsifier, or by directly bonding a solubilizing group to a central polymer of a latex without using an emulsifier. Some latex is also dispersed. The latex using a high-molecular-weight surfactant as the emulsifier and the latex not using the emulsifier are called soap-free latex. The latex used in the present invention is not limited to the type and form of the emulsifier, but it is more preferable to use a soap-free latex having excellent storage stability of the ink.

Further, recently, besides latex having a uniform central polymer, there is also a core-shell type latex having a different composition at the center and the outer edge of the polymer particles, and this type of latex is preferably used. it can.

The average particle size of the latex in the present invention is 1
It is preferably at most 50 nm, more preferably at most 50 nm.

The average particle size of the latex can be easily measured using a commercially available measuring device using a light scattering method or a laser Doppler method.

The solid content of the latex in the present invention is 0.1 to 10% based on the total mass of the ink.
It is particularly preferred that it is 3 to 5%. If the addition amount is less than 0.1%, it is difficult to exert a sufficient effect on the water resistance, and if it exceeds 10%, the ink viscosity tends to increase and the pigment dispersion particle size tends to increase over time, and the ink storage stability tends to increase. Problems often arise.

In the present invention, an electric conductivity regulator can be used, and examples thereof include inorganic salts such as potassium chloride, ammonium chloride, sodium sulfate, sodium nitrate and sodium chloride, and aqueous amines such as triethanolamine. .

The ink of the present invention may further contain a preservative, a fungicide, a viscosity modifier and the like, if necessary.

The ink jet head used in the ink jet recording method of the present invention may be of an on-demand type or a continuous type. Also, as the discharge method,
Electro-mechanical conversion method (for example, single cavity type, double cavity type, bender type, piston type,
Shared mode type, shared wall type, etc.), electricity-
Specific examples include a heat conversion method (for example, a thermal ink jet type, a bubble jet (registered trademark) type, etc.), an electrostatic suction method (for example, an electric field control type, a slit jet type, etc.), and a discharge method (for example, a spark jet type, etc.). As a typical example, any discharge method may be used.

In the present invention, the droplets ejected from the ink jet head are preferably smaller, more preferably an appropriate amount of 10 pl or less, and further preferably 6 pl or less. This reduces the graininess by making the droplets smaller, so-called “roughness”
This is because it is possible to form a high-quality image free from defects.

In the present invention, it is preferable that a large number of ink jet nozzles are formed in the ink jet head, more preferably 64 or more nozzles are formed, more preferably 128 or more nozzles are formed.

This is because, when low-density ink is ejected in small droplets, a large number of droplets must be ejected in order to obtain a desired image density. I will. Therefore, the image forming time can be reduced by increasing the number of nozzles.

The dot diameter can be measured by various methods. For example, at least 100 dots or more of images are photographed by a transmission type or reflection type optical microscope, and this image is image-Pro (manufactured by Media Cybernetics) or the like. Can be obtained by performing statistical processing using image analysis software.

As described above, the present inventors degrade the image quality when using the conventional pigment ink because the diameter of the dot on the recording medium is small when using the pigment ink. I found that.

Generally, the dye is uniformly dissolved in the ink. Therefore, when the dye ink is used, droplets discharged from the ink jet head land on the surface of the recording medium and then penetrate into the surface and inside of the recording medium.・ Move with the solvent in the process of diffusion. Therefore, there is a tendency that dots having a size substantially equal to that of the solvent are given. On the other hand, in the case of the pigment ink, since the pigment is dispersed without being dissolved, the pigment particles quickly adhere to each other after the pigment ink lands on the recording medium, and the diameter of the dot uses the dye ink. It is significantly smaller than the case. In particular, this tendency is remarkable when an ink jet recording medium containing inorganic fine particles and having a void layer formed therein is used for outputting a high-quality image in recent years.

As a result of intensive studies to improve this, it was found that the intended high-quality ink-jet recorded image can be obtained by using the ink-jet ink containing the compound represented by the general formula (1). I found it. At the same time, it was revealed that the excellent preservability inherent to the pigment ink was exhibited, and that the ink jet recorded image also exhibited excellent image preservability, that is, bleeding, light resistance, heat and humidity resistance, and the like.

[0111]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, (%) indicates% by mass unless otherwise specified.

Embodiment 1 1. Preparation of Recording Paper 1 <Preparation of Silica Dispersion 1> The average particle size of the primary particles is about 0.
125 kg of 007 μm fumed silica (A300 manufactured by Nippon Aerosil Co., Ltd.) was added to a jet stream inductor mixer TD manufactured by Mitamura Riken Kogyo Co., Ltd.
Using S, the mixture was suction-dispersed at room temperature in 620 L of pure water adjusted to pH = 2.5 with nitric acid, and the total amount was made up to 694 L with pure water.

<Preparation of Silica Dispersion 2> 1.63 kg of cationic polymer (P-1), 2.2 L of ethanol, n-
An aqueous solution containing 1.5 L of propanol (pH = 2.
3) Add 69.4 L of silica dispersion 1 to 18 L with stirring, then add 260 g of boric acid and 230 g of borax
Is added, and an antifoaming agent SN381 is added.
1 g (manufactured by San Nopco Co., Ltd.) was added.

This mixture was dispersed with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd., and the whole amount was made up to 97 L with pure water to prepare a silica dispersion liquid 2.

[0115]

Embedded image

<Preparation of Coating Solution> Next, the following coating solution was prepared using the silica dispersion liquid 2 obtained as described above.

The following additives were sequentially mixed with 600 ml of the silica dispersion liquid 2 at 40 ° C. while stirring.

6 ml of 10% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA203) 5 ml of 5% aqueous solution of polyvinyl alcohol (PVA235, manufactured by Kuraray Industries, Ltd.) Polyalkylenepolyamine / dicyandiamide-based polycondensate (Nippon Kayaku Co., Ltd.) (Company: Kayafix M) 0.4g Make up to 1000ml with pure water.

<Preparation of Recording Paper> Polyethylene coated paper in which both sides of a base paper having a thickness of 170 g / m ² are coated with polyethylene (polyethylene on the ink receiving layer side contains 8% anatase type titanium oxide; ink receiving layer side To 0.05
g / m ² gelatin subbing layer, Tg about 80 ° C on opposite side
Having a latex polymer of 0.2 g / m ² as a back layer) so as to have a wet film thickness of 210 μm, cool once to about 7 ° C., dry by blowing air at 20 to 65 ° C. Recording paper 1 was produced.

[0120] 2. Preparation of Recording Paper 2 <Preparation of Silica Dispersion 3> The average particle size of the primary particles is about 0.5.
012 μm fumed silica (manufactured by Tokuyama Corporation: QS
-20) After suction-dispersing 125 kg at room temperature in 620 L of pure water adjusted to pH = 2.5 with nitric acid using a jet stream inductor mixer TDS manufactured by Mitamura Riken Kogyo Co., Ltd., the total amount was 694 L. Finished with pure water.

<Preparation of silica dispersion 4> 1.14 kg of cationic polymer (P-1), 2.2 L of ethanol, n-
An aqueous solution containing 1.5 L of propanol (pH = 2.
3) 69.4 L of silica dispersion 3 was added to 18 L with stirring, and then 260 g of boric acid and 230 g of borax were added.
Is added, and an antifoaming agent SN381 is added.
1 g (manufactured by San Nopco Co., Ltd.) was added.

This mixture was dispersed with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd., and the total amount was made up to 97 L with pure water to prepare a silica dispersion 4.

<Preparation of Coating Solution> Next, the following coating solution was prepared using the silica dispersion 4 obtained as described above.

The following additives were sequentially mixed with 600 ml of the silica dispersion 4 while stirring at 40 ° C.

6% of a 10% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA203) 5 ml of a 5% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235) 260 ml The total volume is made up to 1,000 ml with pure water.

<Preparation of Recording Paper> Polyethylene coated paper obtained by coating both sides of a base paper having a thickness of 170 g / m ² with polyethylene (polyethylene on the ink receiving layer side contains 8% anatase type titanium oxide; ink receiving layer side To 0.05
g / m ² gelatin subbing layer, Tg about 80 ° C on opposite side
Having a latex polymer of 0.2 g / m ² as a back layer) so as to have a wet film thickness of 210 μm, cool once to about 7 ° C., dry by blowing air at 20 to 65 ° C. Recording paper 2 was produced.

[0127] 3. Preparation of Recording Paper 3 According to the method described in Example 1 of JP-A-11-1060, a dispersion containing colloidal sol of alumina hydrate and polyvinyl alcohol solution as inorganic fine particles was obtained.
This was coated with polyethylene on both sides of a base paper having a thickness of 170 g / m ² (polyethylene on the ink receiving layer side containing 8% anatase type titanium oxide;
The ink receiving layer side of gelatin subbing layer of 0.05 g / m ^2, the wetting film thickness having a Tg latex polymer of from about 80 ° C. as a back layer 0.2 g / m ²⁾ on the opposite side 2
It was applied so as to have a thickness of 10 μm, and dried to prepare an inkjet recording paper 3.

The surfaces of the recording sheets 1 to 3 obtained here are
Observation with a scanning electron microscope confirmed the presence of voids in any of the papers.

[0129] 4. Preparation of ink <Preparation of magenta pigment dispersion> I. Pigment Red 122 105 g Joncryl 61 (acryl-styrene resin, manufactured by Johnson Co.) 60 g Ethylene glycol 100 g Ion-exchanged water 130 g These are mixed and mixed with a sand grinder filled with zirconia beads of 0.5 mm at a volume ratio of 50%. It was dispersed to obtain a magenta pigment dispersion. The average particle size of the obtained pigment dispersion was 85 nm. The particle size was measured by using a Zetasizer 1000 manufactured by Malvern.

<Preparation of Ink 1> Magenta Pigment Dispersion 113 g Triethylene glycol monobutyl ether 100 g Glycerin 50 g Perex OT-P (Kao Corporation) 3 g Proxel GXL (Abisia Corporation) 0.2 g After finishing to 1000 g with water and sufficiently stirring, the mixture was passed twice through a millipore filter having a pore size of 1 μm to obtain Ink 1.

Further, the kind of ink solvent, the amount of ink solvent added,
The surfactant was changed as shown in Table 1, and the inks 2 to 7,
Comparative inks 8 and 9 (compounds not included in claim 5) were obtained. For comparison, a color inkjet printer MJ-8 manufactured by Seiko Epson Corporation was used.
A pure magenta dye color ink MJIC4C for 00 was used as ink 10.

[0132]

[Table 1]

The number of ejection nozzles = 128,
Using a piezo-type inkjet testing machine with a nozzle diameter of 22 μm and a discharge frequency of 30 kHz,
Wedge images were output at a pixel density of 720 dots per inch on the top, and image samples 101 to 120 were produced. Here, the driving voltage of the nozzle was changed to adjust the droplet speed to 8 m / sec. At this time, the measured amount of the ejected ink droplets was 6 pl.

The structure of the head 1 of the above-mentioned piezo type ink jet tester is as shown in FIG.
FIG. 1B is a sectional view of the head 1 taken along line AA.

In FIG. 1A, a head 1 having five discharge nozzles is illustrated for explanation, but a head having 128 nozzles is used in the embodiment. Piezo element 2 for discharging ink droplets by displacement of piezo element
Are provided on the head corresponding to each ejection nozzle.
Further, a driver IC 3 for supplying a driving signal and a heating signal to the piezo element is disposed on the ink flow path (ink reservoir). Further, a thermistor 4 is provided on the discharge nozzle near the piezo element, and constitutes a temperature measuring means.

A dot image at the Dmin portion of the obtained ink jet image was photographed using a reflection type optical microscope, and the diameter of the dot was measured. Here, for the purpose of comparison with the dye ink, the ratio of the diameter of the dot in each inkjet image to the diameter of the dot of the image in which the dye ink 10 was output on the same paper was obtained (= the diameter of the measured dot / the image 118 or 119 or 120 dot diameter). The reflection density of the Dmax part (maximum reflection density)
With an optical densitometer (X-Rite93 manufactured by X-Rite)
8).

The image quality (streak unevenness) of the obtained image is
It was determined by visual evaluation. The Dmax part of the inkjet image was evaluated in the following four grades.

4: The image has glossiness and stripe unevenness cannot be distinguished. 3: The image has glossiness but stripe unevenness is conspicuous. 2: The image has little glossiness and stripe unevenness is noticeable. 1: The image has glossiness. The obtained image sample was irradiated with light using a xenon fade meter (illuminance: 70,000 lux) for 14 days to evaluate light fastness. In the evaluation, a sample having an initial concentration of about 1.0 was used.
The ratio of the residual concentration after 4 days was determined and expressed as a residual ratio. Table 2 shows the results.

[0139]

[Table 2]

As shown in Table 2, the samples of the present invention all had a large dot diameter, a high reflection density and excellent image quality.

On the other hand, in each of the comparative samples, the dot diameter was small, the reflection density was low, and the result was further inferior in image quality. Comparative Samples 118 to 120 using dye inks having excellent image quality were significantly inferior in light resistance, but it was found that the sample of the present invention had both image quality and light resistance.

Example 2 <Preparation of Ink 21> Hostfine Black T (manufactured by Clariant Co., Ltd., average particle diameter: 50 nm) 167 g 1,2-hexanediol 150 g ethylene glycol 220 g diethylene glycol 90 g Levenol WX (manufactured by Kao Corporation) 3 g Proxel GXL 0.2 g This was made up to 1000 g with ion-exchanged water, stirred sufficiently, and then passed twice through a 1 μm-pore-size Millipore filter machine to obtain Ink 21. Further, the ink solvents were changed as shown in Table 3 to obtain inks 22 to 27. For comparison, genuine black dye color ink MJIC4 for a color inkjet printer MJ-800 manufactured by Seiko Epson Corporation was used as ink 28.

[0143]

[Table 3]

Using the obtained ink in Example 1, the number of ejection nozzles = 128, nozzle diameter = 22 μm, ejection frequency =
A wedge image was output at a pixel density of 720 dots per inch on the recording papers 1 to 3 prepared in Example 1, using a piezo-type inkjet tester at 30 kHz.
Image samples 201 to 217 were produced. Here, the driving voltage of the nozzle was changed so that the droplet speed was 8 m / sec.
It was adjusted to be. At this time, the measured amount of the ejected ink droplets was 6 pl.

A dot image at the Dmin portion of the obtained inkjet image was photographed using a reflection type optical microscope, and the diameter of the dot was measured. Here, for the purpose of comparison with the dye ink, the ratio of the diameter of the dot in each inkjet image to the diameter of the dot of the image in which the dye ink 28 was output on the same paper was determined (= the diameter of the measured dot / the image 215 or 216 or 217 dot diameter). Further, the reflection density of the Dmax part is measured by an optical densitometer (X
-Rite X-Rite 938).

The image quality of the obtained image was evaluated in the same manner as in Example 1. Further, the light resistance of the obtained image sample was evaluated in the same manner as in Example 1. Table 4 shows the results of the evaluation.

[0147]

[Table 4]

As shown in Table 4, the samples of the present invention all had a large dot diameter, a high reflection density and excellent image quality.

On the other hand, in each of the comparative samples, the dot diameter was small, the reflection density was low, and the result was further inferior in image quality. Comparative samples 215 to 217 using dye inks having excellent image quality were significantly inferior in light resistance, but it was found that the sample of the present invention had both image quality and light resistance.

Example 3 1. Preparation of Yellow Ink <Yellow Pigment Dispersion> I. Pigment Yellow 74 95 g Demol C 65 g Ethylene glycol 100 g Ion-exchanged water 120 g These were mixed and dispersed using a sand grinder filled with 0.5 mm zirconia beads at a volume ratio of 50% to obtain a yellow pigment dispersion. The average particle size of the obtained pigment dispersion was 122 nm.

<Ink 31> Yellow pigment dispersion 100 g Ethylene glycol 50 g Triethylene glycol monobutyl ether 100 g Orfin 1010 5 g Proxel GXL 0.2 g After finishing this to 1,000 g with ion-exchanged water and stirring sufficiently, a millipore filter having a pore diameter of 1 μm The ink 31 was obtained by passing the filter twice. Further, triethylene glycol monobutyl ether was replaced with the same mass of ethylene glycol to obtain Ink 32.

2. Preparation of magenta ink An ink was prepared according to the method of manufacturing ink 1 described in Example 1,
This was designated as ink 33. Ink 34 was obtained by replacing triethylene glycol monobutyl ether used as a solvent with ethylene glycol of the same mass.

[0153] 3. Preparation of magenta light-colored ink <Ink 35> Magenta pigment dispersion described in Example 1 28 g Diethylene glycol monobutyl ether 100 g Glycerin 50 g Perex OT-P 3 g Proxel GXL 0.2 g After finishing this to 1,000 g with ion-exchanged water and stirring thoroughly, The mixture was passed twice through a millipore filter having a pore size of 1 micron to obtain an ink 35. Further, 1,2-hexanediol was replaced with the same mass of ethylene glycol to obtain ink 36.

[0154] 4. Preparation of Cyan Ink <Cyan Pigment Dispersion> I. Pigment Blue 15: 3 100 g Demol C 68 g Diethylene glycol 100 g Deionized water 125 g These were mixed and dispersed using a sand grinder filled with 0.5% zirconia beads by 50% by volume to obtain a cyan pigment dispersion. The average particle size of the obtained pigment dispersion was 105 nm.

<Ink 37> Cyan pigment dispersion 98 g 1,2-hexanediol 100 g Ethylene glycol 50 g Levenol WX 3 g Proxel GXL 0.2 g After finishing this to 1,000 g with ion-exchanged water and stirring sufficiently, the millipore having a pore diameter of 1 μm was obtained. The ink 37 was obtained by passing twice through a filter machine. Further, 1,2-hexanediol was replaced with glycerin of the same mass, and ink 3
8 was obtained.

[0156] 5. Preparation of cyan light-colored ink <Ink 39> Cyan pigment dispersion 24.5 g 1,2-pentanediol 100 g ethylene glycol 50 g Levenol WX 3 g Proxel GXL 0.2 g After finishing this with ion-exchanged water to 1000 g, and stirring sufficiently, Ink 39 was obtained by passing twice through a Millipore filter having a pore size of 1 μm. Further, 1,2-hexanediol was replaced with glycerin of the same mass, and ink 4
0 was obtained.

[0157] 6. Preparation of Black Ink <Ink 41> Hostfine Black T (manufactured by Clariant Co., Ltd., average particle diameter 50 nm) 167 g Triethylene glycol monobutyl ether 150 g Ethylene glycol 75 g Levenol WX 3 g Proxel GXL 0.2 g After finishing and stirring sufficiently, the mixture was passed twice through a millipore filter having a pore size of 1 μm to obtain ink 41. Further, ink 42 was obtained by replacing triethylene glycol monobutyl ether with diethylene glycol having the same mass.

The obtained inks were combined as shown in Table 5, and using a color ink jet printer PM-770C manufactured by Seiko Epson Co., Ltd., the recording papers 1 to 3 prepared in Example 1 and a comparison paper for a copying machine were used. Discharged on plain paper. Here, as the output image, high-definition color digital standard image data “N5-bicycle” (issued in December 1995) issued by the Japan Standards Association is used.

The chart portion of the obtained print, the stripes on the wall behind, the spokes of the bicycle, the gut of the racket, and the clock portion were visually judged, and the ink absorption, sharpness, stripe unevenness and gloss were determined according to the following criteria. Was evaluated. Table 5 shows the results.

1. Ink absorbency A: No color bleeding at the boundary between the clock and chart parts B: Slight bleeding at the clock part but no bleeding at the chart part C: Characters are almost crushed at the clock part Bleeding occurs in less than about half of the border area in the chart area. D: Border color blur is observed in most of the chart border area.

[0161] 2. Sharpness a: Stripes on the wall behind, spokes of the bicycle, and guts of the racket can be clearly distinguished b: Spokes of the bicycle and guts of the racket can be clearly distinguished, but among the stripes on the wall behind, the line width is narrow The part is crushed and cannot be clearly distinguished c: The spokes of the bicycle can be clearly distinguished, but the gutter of the wall stripe and racket behind cannot be clearly distinguished d: The stripe of the wall behind, bicycle spokes and racket Both guts have blurred boundaries and appear to be blurred.

[0162] 3. Streak unevenness / gloss 4: Gloss on clock face and chart part, streak cannot be determined. 3: Gloss on clock face and chart part.
Streak unevenness is noticeable 2: There is little glossiness on the clock face and chart part,
Streak unevenness is conspicuous 1: The clock face and the chart portion have no glossiness and are rough on the entire surface.

[0163]

[Table 5]

As shown in Table 5, of the comparative samples,
It can be seen that the image sample combined with plain paper is clearly inferior in ink absorbency and sharpness to the image sample using the recording paper having the void layer.

Further, even when a recording paper having a void layer is used,
The image sample formed from the ink not using the ink solvent of the present invention was inferior in stripe unevenness and gloss.

On the other hand, it was found that all of the image samples in the combination of the present invention were excellent in sufficient ink absorption and sharpness, excellent in stripe unevenness and gloss, and provided images with excellent image quality.

Example 4 1. Preparation of Yellow Ink <Yellow Pigment Dispersion> I. Pigment Yellow 74 95 g Demol C 65 g Ethylene glycol 100 g Ion-exchanged water 120 g These were mixed and dispersed using a sand grinder filled with 0.5 mm zirconia beads at a volume ratio of 50% to obtain a yellow pigment dispersion. The average particle size of the obtained pigment dispersion was 120 nm.

<Ink 51> Yellow pigment dispersion 100 g Ethylene glycol 240 g Diethylene glycol 120 g Ethylene glycol monobutyl ether 100 g Megafac F-470 (manufactured by Dainippon Ink and Chemicals, Inc.) 2 g Proxel GXL 0.2 g This was ion-exchanged with water. After finishing to 1000 g and sufficiently stirring, the mixture was passed twice through a millipore filter having a pore size of 1 μm to obtain ink 51. Further, triethylene glycol monobutyl ether was replaced with the same mass of ethylene glycol to obtain ink 52.

[0169] 2. Preparation of magenta ink <Preparation of magenta pigment dispersion> I. Pigment Red 122 105 g Joncryl 61 60 g Ethylene glycol 100 g Ion-exchanged water 130 g These were mixed and dispersed using a sand grinder filled with 0.5% zirconia beads by 50% by volume to obtain a magenta pigment dispersion. The average particle size of the obtained pigment dispersion was 90 nm.

<Preparation of Ink 53> Magenta Pigment Dispersion 113 g Ethylene glycol 240 g Glycerin 145 g 1,2-Hexanediol 75 g Perex OT-P 3 g Proxel GXL 0.2 g This was finished to 1,000 g with ion-exchanged water and stirred sufficiently. Thereafter, the mixture was passed twice through a millipore filter having a pore size of 1 μm to obtain an ink 53.

Ink 54 was obtained by replacing 1,2-hexanediol used as a solvent with diethylene glycol having the same mass.

[0172] 3. Preparation of magenta light-colored ink <Ink 55> Magenta pigment dispersion liquid 28 g Propylene glycol 400 g 1,2-hexanediol 60 g Levenol WX 3 g Proxel GXL 0.2 g After finishing this to 1,000 g with ion-exchanged water and stirring sufficiently, the pore diameter was 1 μm. Was passed twice through a Millipore filter machine to obtain ink 55. Further, 1,2-hexanediol was replaced with propylene glycol of the same mass to obtain ink 56.

[0173] 4. Preparation of Cyan Ink <Cyan Pigment Dispersion> I. Pigment Blue 15: 3 100 g Demol C 68 g Diethylene glycol 100 g Deionized water 125 g These were mixed and dispersed using a sand grinder filled with 0.5% zirconia beads by 50% by volume to obtain a cyan pigment dispersion. The average particle size of the obtained pigment dispersion was 98 nm.

<Ink 57> Cyan pigment dispersion 98 g Triethylene glycol monobutyl ether 120 g Glycerin 360 g Megafac F-144D (manufactured by Dainippon Ink and Chemicals, Inc.) 2 g Proxel GXL 0.2 g This is made up to 1000 g with ion-exchanged water. After finishing and stirring sufficiently, the mixture was passed twice through a millipore filter having a pore size of 1 μm to obtain ink 57. Further, triethylene glycol monobutyl ether was replaced with glycerin of the same mass to obtain ink 58.

[0175] 5. Preparation of Cyan Light Ink <Ink 59> Cyan pigment dispersion 24.5 g 1,2-pentanediol 75 g ethylene glycol 200 g glycerin 185 g Levenol WX 3 g Proxel GXL 0.2 g This was finished to 1,000 g with ion-exchanged water and thoroughly stirred. Thereafter, the mixture was passed twice through a millipore filter having a pore size of 1 μm to obtain an ink 59. Further, 1,2-pentanediol was replaced with glycerin of the same mass, and ink 6
0 was obtained.

[0176] 6. Preparation of Black Ink <Ink 61> Hostfine Black T 167 g Triethylene glycol monobutyl ether 50 g Ethylene glycol monophenyl ether 50 g Ethylene glycol 240 g Propylene glycol 120 g Olfine 1010 4 g Proxel GXL 0.2 g After stirring, the mixture was passed twice through a Millipore filter having a pore size of 1 μm to obtain Ink 61. Further, triethylene glycol monobutyl ether and ethylene glycol monophenyl ether were each replaced with diethylene glycol having the same mass to obtain ink 62.

The obtained inks were combined as shown in Table 6 and discharged onto recording papers 1 to 3 prepared in Example 1 and plain paper for comparison using a color inkjet printer PM-770C manufactured by Seiko Epson Corporation. did. Here, as the output image, high-definition color digital standard image data “N5-bicycle” (issued in December 1995) issued by the Japan Standards Association is used.

The chart portion of the obtained print, the stripes on the wall behind, the spokes of the bicycle, the gut of the racket, and the clock portion were visually judged, and the ink absorptivity, sharpness, Streak unevenness and gloss were evaluated. Table 6 shows the results.

[0179]

[Table 6]

As shown in Table 6, among the comparative samples,
It can be seen that the image sample combined with plain paper is clearly inferior in ink absorbency and sharpness to the image sample using the recording paper having the void layer.

Further, even when a recording sheet having a void layer is used,
The image sample formed from the ink not using the ink solvent of the present invention was inferior in stripe unevenness and gloss.

On the other hand, with the combination of the present invention, all of the image samples were found to be excellent in sufficient ink absorbency and sharpness, excellent in stripe unevenness and gloss, and to give images of excellent image quality.

[0183]

According to the present invention, it is possible to provide an image forming method for forming an ink jet recorded image having excellent image quality and image storability.

[Brief description of the drawings]

FIG. 1 is a configuration diagram and a cross-sectional view illustrating an example of a head of a piezo-type inkjet tester used in the present invention.

[Explanation of symbols]

 1 Head 2 Piezo Element 3 Driver IC 4 Thermistor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shuji Kida 1st Konica Corporation, Sakura-cho, Hino-shi, Tokyo In-house (72) Inventor Hidenobu Oya 1st-place Konica Corporation, Sakura-cho, Hino-shi, Tokyo In-house (72) Inventor Masaki Nakamura No. 1 Sakuracho, Hino-shi, Tokyo Konica Stock Exchange In-house F-term (reference) 2C056 FC01 2H086 BA52 BA53 BA62 4J039 AB01 AB02 AB07 AD06 AD07 AD09 AD12 AD20 AE04 AE07 BA12 BC02 BC03 BC07 BC14 BC73 BE01 BE12 CA06 EA33 EA44 GA24

Claims (7)

[Claims] An ink-jet image forming method for forming an image on an ink-jet recording medium having inorganic particles on a support and having a void layer formed thereon, using an ink having at least water, an ink solvent and a pigment. An ink-jet image forming method, wherein an ink containing at least one of the compounds represented by the following general formula (1) is used as a solvent. General formula (1) AB (wherein, A represents a group containing a hydrophilic substituent, and B represents a hydrophobic group.) 2. A compound represented by the general formula (1):
2. The ink jet image forming method according to claim 1, wherein the ink occupies at least 50% of the total ink solvent. 3. The method according to claim 1, wherein the proportion of the ink solvent contained in the ink exceeds 45%, and a part or all of the ink solvent is a compound represented by the general formula (1). Item 6. The inkjet image forming method according to Item 1. 4. In the above general formula (1), the hydrophilic substituent of A is a hydroxy group, and the hydrophobic group of B is an aliphatic or aromatic hydrocarbon group having 3 to 10 carbon atoms. The inkjet image forming method according to any one of claims 1 to 3, wherein: 5. A polyhydric alcohol ether derivative or carbon, wherein at least one hydroxy group is unsubstituted and at least one hydroxy group is substituted by an aliphatic or aromatic hydrocarbon group having 4 to 8 carbon atoms. 5. The ink-jet image forming method according to claim 4, wherein the method is an aliphatic 1,2-diol having 4 to 8 atoms. 6. A polyhydric alcohol ether derivative or an aliphatic 1,2-diol having 4 to 8 carbon atoms is ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, 1,2-hexanediol. The inkjet image forming method according to claim 5, wherein the compound is at least one compound selected from the group consisting of 1,2-pentanediol. 7. The method according to claim 5, wherein the polyhydric alcohol ether derivative or the aliphatic 1,2-diol having 4 to 8 carbon atoms is triethylene glycol monobutyl ether or 1,2-hexanediol. Ink jet image forming method.