JP2003054112A - Ink jet recording medium and ink jet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording medium and an ink jet recording method which meet at least one of requirements: preventing lowering of solid uniformity due to lessening of the diameter of an ink dot on the occasion of using pigment ink; satisfying the properties of circularity of the diameter of the ink dot on the occasion of using the pigment ink; making a printing speed high; improving the durability of the recording medium; and enhancing the quality of a print. SOLUTION: The ink jet recording medium has one or more porous layers on a substrate and the contact angle thereof to the pigment ink having a surface tension of 30-45 mN/m is 30-50 degrees.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording medium and an inkjet recording method using the same.

[0002]

2. Description of the Related Art In recent years, ink jet recording has been rapidly improving in image quality, and is approaching photographic image quality. In addition, the printing speed is also increasing. In particular, regarding the final print quality, the importance of the inkjet recording medium is increasing.

In recent years, an ink jet image recording medium has been developed in which fine particles of an inorganic pigment such as silica or alumina are combined with a small amount of a water-soluble polymer as a binder to form a porous layer. Since the recording medium has a large void portion inside the layer, the ink is rapidly absorbed in the void portion due to the capillary phenomenon, and a large amount of ink can be retained in the void portion inside.
It has the following two features. As a result, there are advantages that the drying property is excellent and the ink dot shape is maintained in a state close to a perfect circle because the ink is rapidly absorbed, and the image is excellent in sharpness.

Further, as an ink jet recording medium,
For example, in Japanese Examined Patent Publication No. 31673/1990, a layer made of thermoplastic organic polymer particles is provided on the surface layer of a recording medium, and after image recording, the thermoplastic organic polymer particles are melted and formed into a film, resulting in a polymer protective film. By forming the film, improvement in water resistance and image quality is achieved.

[0005]

However, when the pigment ink is used for the recording medium having the porous layer, the ink dot diameter itself becomes smaller than that of the dye ink,
Due to this, there is a problem that the solid uniformity becomes low.

Further, an ink jet recording medium having a void type ink absorbing layer has a problem that production efficiency is improved and cost is reduced by suppressing generation of defective products such as cracks in the recording medium.

Further, as described above, the ink jet image is required to have print quality such as gloss and durability which is comparable to the quality of silver salt photograph, and the printing speed is required to be high so that a large quantity can be printed. . In particular, when a layer made of thermoplastic resin particles is provided, there is a problem that the ink absorption speed is significantly reduced as compared with the void type recording medium mainly made of an inorganic pigment. This causes the deterioration of the image quality. In particular, as the printing speed increases, the deterioration of image quality becomes a greater problem.

The present invention has been made in view of the above circumstances, and the present invention provides an ink jet recording medium and an ink jet recording method for solving at least one of the following objects.・ Prevents deterioration of solid uniformity due to the decrease in ink dot diameter when printing with pigment ink ・ Improves the shape of ink dot diameter when printing with pigment ink ・ Increases printing speed ・Improve production efficiency, reduce costs, prevent deterioration of image quality, and improve print quality.

[0009]

The above object can be achieved by any one of the technical means (1) to (15).

(1) An ink jet recording medium having one or more porous layers on a support having a surface tension of 3
The contact angle for pigment ink of 0 to 45 mN / m is 3
An inkjet recording medium having an angle of 0 to 50 degrees.

(2) The ink jet recording medium according to (1), wherein the surface layer contains one or more kinds of thermoplastic resins.

(3) The ink jet recording medium according to (1), characterized in that at least the surface layer is a porous layer.

(4) The ink jet recording medium as described in (3), wherein the surface layer contains an inorganic pigment.

(5) The ink jet recording medium as described in (3) or (4), wherein the surface layer contains one or more kinds of silicon-based emulsions.

(6) The ink jet recording medium as described in any one of (3) to (5), wherein the surface layer contains one or more kinds of activators.

(7) A porous layer containing an inorganic pigment is provided as a lower layer of the surface layer (3) to
The inkjet recording medium according to any one of (6).

(8) The ink jet recording medium according to any one of (3) to (7), wherein the surface layer contains one or more kinds of thermoplastic resins.

(9) An inkjet recording medium having one or more porous layers on a support, wherein at least the surface layer contains at least one thermoplastic resin and at least one silicone emulsion. .

(10) The ink jet recording medium as described in (9), wherein the surface layer is a porous layer.

(11) The ink jet recording medium as described in (9) or (10), wherein the surface layer contains an inorganic pigment.

(12) The ink jet recording medium as described in (9) or (11), wherein the surface layer contains one or more activators.

(13) A porous layer containing an inorganic pigment is provided as a lower layer of the surface layer (9) to
The inkjet recording medium according to any one of (12).

(14) Surface tension of 30 to 45 mN / m
The inkjet recording medium according to any one of (9) to (13), wherein the contact angle with respect to the pigment ink is 30 to 50 degrees.

(15) After recording with the pigment ink on the ink jet recording medium according to any one of (2) and (8) to (14), heat treatment is performed to melt or form a film of the thermoplastic resin. An inkjet recording method characterized by the above.

The inventors of the present invention have conducted various studies to prevent the ink dot diameter from decreasing when printing on an ink jet recording medium having a porous layer using a pigment ink. By preparing the ink jet recording medium so that the contact angle with respect to the pigment ink of 30 to 45 mN / m is 30 to 50 degrees, the ink dot diameter is not reduced even when the pigment ink is used, and the ink dot shape is not true. It was found that the circularity was satisfied.

Further, the present inventors have made an ink jet recording medium having a porous layer containing one or more kinds of thermoplastic resins and one or more kinds of silicone-based emulsions, thereby performing printing using a pigment ink. However, it has been found that the diameter of the ink dot does not become small, the shape of the ink dot satisfies the circularity, and the durability of the recording medium is improved. In addition, this inkjet recording medium,
Since a thermoplastic resin is contained in the surface layer, it is possible to improve the water resistance of an image, to prevent deterioration of the image and to improve the photographic quality, when the inkjet recording medium is subjected to heat treatment after printing with a pigment ink. It was

The present invention will be described in detail below. In the inkjet recording medium of the present invention, it is necessary that a porous layer composed of voids having an ink solvent holding ability is formed on a support, and the porous layer mainly comprises a hydrophilic binder and an inorganic pigment. What is formed by the soft aggregation of is preferable.

Conventionally, various methods for forming a porous layer have been known. For example, a uniform coating solution containing two or more kinds of polymers is coated on a support, and these polymers are mixed with each other in a drying process. A method of phase-separating to form voids, a coating liquid containing solid fine particles and a hydrophilic or hydrophobic binder is coated on a support, and after drying, an inkjet recording paper is treated with water or a liquid containing a suitable organic solvent. A method of immersing solid fine particles to form voids, a method of applying a coating solution containing a compound having a property of foaming during film formation, and then foaming the compound in the drying process to form voids in the film , A method of applying a coating liquid containing porous solid fine particles and a hydrophilic binder onto a support to form voids in the porous fine particles or between the fine particles, approximately the same amount as the hydrophilic binder There is a method of forming solid voids between solid fine particles by applying a coating liquid containing solid fine particles having an upper volume (preferably 1.0 times or more) and / or fine particle oil droplets and a hydrophilic binder on a support. As is known, in the present invention, the porous layer is preferably formed by incorporating various inorganic pigments having an average particle diameter of 100 nm or less (simply referred to as inorganic fine particles).

Examples of the inorganic pigment 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, zinc hydroxide. , Zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudo-boehmite, aluminum hydroxide, lithopone, zeolite, hydroxylation Examples thereof include white inorganic pigments such as magnesium.

The average particle size of the inorganic pigment is the simple average value obtained by observing the particles themselves or the particles appearing on the cross section or surface of the porous layer with an electron microscope and determining the particle size of 1,000 arbitrary particles. It is calculated as (number average). Here, the particle size of each particle is represented by the diameter assuming a circle equal to the projected area.

From the viewpoints of high density image formation, clear image recording and low cost production, it is preferable to use an inorganic pigment selected from silica and alumina or alumina hydrate. Is more preferable.

As the silica, silica synthesized by a usual wet method, colloidal silica, silica synthesized by a gas phase method, or the like is preferably used, and as the silica particularly preferably used in the present invention, colloidal silica or gas is used. Fine particle silica synthesized by the phase method (hereinafter, also referred to as gas phase method fine particle silica) is preferable. Among them, the gas phase method fine particle silica is not only a high porosity but also a cationic used for the purpose of immobilizing a dye. Coarse aggregates are less likely to be formed when added to the polymer, which is preferable. or,
Alumina or alumina hydrate may be crystalline or amorphous, and may have any shape such as irregular particles, spherical particles, and acicular particles.

The inorganic pigment is preferably in a state in which the fine particle dispersion liquid before mixing with the cationic polymer is dispersed up to the primary particles.

In order to obtain the effects of the present invention, the particle size of the inorganic pigment is preferably 100 nm or less.
For example, in the case of the gas phase method fine particle silica, the average particle diameter of the primary particles of the inorganic pigment dispersed in the state of primary particles (particle diameter in a dispersion state before coating) is preferably 100 nm or less, It is more preferably 4 to 50 nm, and most preferably 4 to 20 nm.

As the most preferably used gas phase method fine particle silica having an average primary particle diameter of 4 to 20 nm, for example, Aerosil of Nippon Aerosil Co., Ltd. is commercially available. This gas phase method fine particle silica is, for example, in water,
By using a jet stream inductor mixer manufactured by Mitamura Riken Kogyo Co., Ltd., it is possible to relatively easily disperse even the primary particles by suction and dispersion.

Examples of the hydrophilic binder include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, color genin (κ, ι, λ, etc.), agar, pullulan, water-soluble. Polyvinyl butyral, hydroxyethyl cellulose, carboxymethyl cellulose and the like. It is also possible to use two or more of these water-soluble resins in combination.

The water-soluble resin preferably used in the present invention is polyvinyl alcohol. Examples of the polyvinyl alcohol include, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, polyvinyl alcohol having a cation-modified terminal, polyvinyl alcohol modified with a nonion, or anion-modified polyvinyl alcohol having an anionic group. Modified polyvinyl alcohol is also included.

The polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate preferably has an average degree of polymerization of 1,000 or more, and particularly preferably has an average degree of polymerization of 1,500 to 1,500.
Those of 5,000 are preferably used.

The saponification degree is preferably 70 to 100%, particularly preferably 80 to 99.5%.

As the cation-modified polyvinyl alcohol, for example, primary to tertiary amino groups and quaternary ammonium bases as described in JP-A-61-10483 can be used in the main chain or side chain of the polyvinyl alcohol. 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-vinyl imidazole, N-vinyl-2-methyl imidazole, N
-(3-dimethylaminopropyl) methacrylamide,
Hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1,1-dimethyl-3-)
Examples include dimethylaminopropyl) acrylamide.

The ratio of the cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol% with respect to vinyl acetate.

The anion-modified polyvinyl alcohol is, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-206088, JP-A-6-61.
Copolymers of vinyl alcohol and a vinyl compound having a water-soluble group as described in JP-A Nos. 1-237681 and 63-307979, and JP-A-7-2852.
And modified polyvinyl alcohol having a water-soluble group as described in No. 65.

As the nonion-modified polyvinyl alcohol, for example, a polyvinyl alcohol derivative obtained by adding a polyalkylene oxide group to a part of vinyl alcohol as described in JP-A-7-9758, JP-A-8-25795. And a block copolymer of a vinyl compound having a hydrophobic group and a vinyl alcohol described in 1.

Polyvinyl alcohol may be used in combination of two or more types such as different degree of polymerization or modification.

The addition amount of the inorganic pigment used in the porous layer having voids having the ink solvent holding ability is largely dependent on the ink absorption capacity, the void ratio of the void layer, the type of inorganic fine particles and the type of water-soluble resin. Generally, 5 to 30 g, preferably 10 to 25 g per 1 m ² of recording paper, although depending on
Is.

The mass ratio of the inorganic pigment used for retaining the ink solvent to the water-soluble resin is usually 2: 1 to 20: 1, and preferably 3: 1 to 10: 1.

As the other type of void type, a polyurethane resin emulsion, a water-soluble epoxy compound and / or
Or in combination with acetoacetylated polyvinyl alcohol,
Further, the ink absorbing layer may be formed by using a coating liquid in which epichlorohydrin polyamide resin is used in combination. The polyurethane resin emulsion in this case is preferably a polyurethane resin emulsion having a polycarbonate chain, a polycarbonate chain and a polyester chain and having a particle diameter of 3.0 μm, and the polyurethane resin of the polyurethane resin emulsion is a polycarbonate polyol, a polyol having a polycarbonate polyol and a polyester polyol. Polyurethane resin obtained by reacting with an aliphatic isocyanate compound has a sulfonic acid group in the molecule, and further has an epichlorohydrin polyamide resin and a water-soluble epoxy compound and / or acetoacetylated vinyl alcohol. preferable. It is presumed that in the ink absorbing layer using the polyurethane resin, weak cations and anions are formed, and along with this, voids having an ink solvent absorbing ability are formed and an image can be formed.

In the ink jet recording medium of the present invention, it is preferable that the water-soluble resin is hardened by a hardening agent in order to obtain a 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 resin or a compound which promotes the reaction between different groups of the water-soluble resin. It is appropriately selected and used.

Specific examples of the hardener include 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 salts thereof, borax, aluminum alum and the like.

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

Most preferred are hardeners selected from boric acid and its salts. In the present invention, as boric acid or a salt thereof, an oxygen acid having a boron atom as a central atom and a salt thereof are shown, and specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, octaboric acid and These salts are included.

The total amount of the above-mentioned hardeners varies depending on the type of water-soluble resin, the type of hardener, the type of inorganic fine particles and the ratio to the water-soluble resin, but usually 1 to 600 mg per 1 g of the water-soluble resin, It is preferably 10 to 300 mg.

The above-mentioned hardener may be added to the coating solution at the time of applying the coating solution used for forming the porous layer comprising the voids having the ink holding ability of the present invention, or in advance. The coating liquid used for forming the porous layer may be coated on a support coated with the coating liquid containing a hardening agent. Further, the coating solution (containing no hardener) used for forming the porous layer can be supplied by coating and drying and then overcoating with the hardener solution. Therefore, of these, the method of adding a hardener to the coating liquid used for forming the porous layer and coating the coating liquid is preferable.

A cationic polymer may be added to the ink jet recording medium according to the present invention for the purpose of improving the water resistance of the obtained image. The cationic polymer to be used can be used without particular limitation, but a particularly preferable one is that the mass average molecular weight is 2,000 to 10.
It is 50,000.

The cationic polymer is preferably a polymer having a quaternary ammonium salt group in the molecule, particularly preferably a homopolymer of a monomer having a quaternary ammonium salt group or another copolymerizable one or more monomers. It is a copolymer with the monomer. Examples of the monomer having a quaternary ammonium salt group include the ethylenically unsaturated monomers having a cationic group described above.

[0058] cationic polymers having a quaternary ammonium base in the molecule (water soluble) is an ink jet recording paper 1 m ² per usually 0.1 to 10 g, preferably 0.
It is used in the range of 2 to 5 g.

In the porous layer, the total amount of voids (void volume) is preferably 20 ml or more per 1 m ² of the image recording medium. If the void volume is less than 20 ml / m ² ,
When the amount of ink during printing is small, the ink absorbency is good, but when the amount of ink is large, the ink is not completely absorbed, causing problems such as deterioration of image quality and delay of drying property. Cheap.

The upper limit of the void volume is not particularly limited, but it is preferable to set the thickness of the void layer to about 70 μm or less so as not to deteriorate the physical properties of the film such as cracks.

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

The support that can be used in the ink jet recording medium of the present invention is a support that has been conventionally used in ink jet recording media, for example, paper support such as plain paper, art paper, coated paper and cast coated paper. A body, a plastic support, a paper support whose both surfaces are coated with polyolefin, a composite support obtained by laminating these, and the like can be appropriately selected and used.

In the ink jet recording medium of the present invention, for the purpose of increasing the adhesive strength between the support and the ink absorbing layer,
Prior to applying the ink absorbing layer, it is preferable to subject the support to corona discharge treatment, subbing treatment, or the like. Furthermore, the recording medium of the present invention does not necessarily have to be colorless, and may be colored recording paper.

In the ink jet recording medium of the present invention, the use of a paper support obtained by laminating both sides of the base paper support with polyethylene or the like allows a recorded image to be close to a photographic quality, and a high quality image can be obtained at low cost. , Particularly preferred. A paper support laminated with such polyethylene will be described below.

The base paper used for the paper support is mainly made of wood pulp, and if necessary, synthetic paper such as polypropylene or synthetic fiber such as nylon or polyester is used in addition to wood pulp. As wood pulp, LBKP, LBSP, NBKP, NBSP,
Any of LDP, NDP, LUKP, and NUKP can be used, but LBKP, NBSP, which has a large amount of short fibers,
It is preferable to use more LBSP, NDP, and LDP. However, the ratio of LBSP and / or LDP is 1
0 mass% or more and 70 mass% or less are preferable.

As the above-mentioned pulp, a chemical pulp containing few impurities (sulfate pulp or sulfite pulp) is preferably used, and a pulp whose whiteness is improved by bleaching is also useful. The base paper contains sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength enhancers such as starch, polyacrylamide and polyvinyl alcohol, optical brighteners and polyethylene glycols. A water retention agent such as, a dispersant, and a softening agent such as quaternary ammonium can be appropriately added.

The freeness of pulp used for papermaking is CSF.
Is preferably 200 to 500 ml, and the fiber length after beating is 30 to 70% of the sum of the mass% of the 24 mesh residue and the mass% of the 42 mesh residue defined in JIS-P-8207. preferable. The mass% of the 4-mesh residue is preferably 20 mass% or less. The basis weight of the base paper is preferably 30 to 250 g / m ² , and particularly 50 to ²
00 g / m ² is preferred. The thickness of the base paper is 40-250μ
m is preferred. The base paper can be given a high smoothness by calendering at the papermaking stage or after the papermaking. Base paper density is 0.7 to 1.2 g / m ² (JIS-P-8118)
Is common. Furthermore, the stiffness of base paper is JIS-P-814.
20 to 200 g is preferable under the conditions specified in 3. A surface sizing agent may be applied to the surface of the base paper, and as the surface sizing agent, the same sizing agent as that which 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-P-8113.

The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but LLDPE (linear rhodity polyethylene), polypropylene, etc. are also partially used. Can be used. In particular, the polyethylene layer on the ink absorption layer side is preferably one in which rutile or anatase type titanium oxide is added to polyethylene to improve opacity and whiteness, as is widely used in photographic printing paper. The titanium oxide content is usually 3 to 20 mass% with respect to polyethylene,
It is preferably 4 to 13% by mass.

The polyethylene-coated paper can be used as a glossy paper, or when a polyethylene is melt-extruded on the surface of a base paper for coating, a so-called patterning treatment is carried out to obtain a matte surface which can be obtained by ordinary photographic printing paper. Those having a silky surface can also be used in the present invention.

The amount of polyethylene used on the front and back sides of the base paper is selected so as to optimize curling under low humidity and high humidity after providing the void layer and the back layer, but the polyethylene layer on the void layer side is usually used. Is 20 to 40 μm, and the back layer side is 10
It is in the range of 30 μm.

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

1. Tensile strength: JIS-P-8113
It is preferable that the strength is 20 to 300 N in the vertical direction and 10 to 200 N in the horizontal direction with the strength defined in 2. Tear strength: A method defined in JIS-P-8116, 0.1 to 20 N in the longitudinal direction and 2 to 20 N in the lateral direction.
Is preferred. 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-P-8119,
It may be less than this for so-called typed products. Surface roughness: The surface roughness defined by JIS-B-0601 has a maximum height of 10 μ per reference length of 2.5 mm.
It is preferably m or less. Opacity: When measured by the method specified in JIS-P-8138, 80% or more, particularly 85 to 98% is preferable. Whiteness: L ^* specified by JIS-Z-8729,
a ^* and b ^* are L ^* = 80 to 95, a ^* = − 3 to +5, b ^*
It is preferable that ==-6 to +2. Surface gloss: 6 specified in JIS-Z-8741
9. The 0 degree specular gloss is preferably 10 to 95%. Clark stiffness: Clark stiffness in the conveying direction of the recording medium 50~300cm ^2/100 in which the support is preferably 10. Water content of inner paper: usually 2 to 100% by mass, preferably 2 to 6% by mass relative to the inner paper. The invention according to claim 1 has a surface tension of 30 to 45 mN / m.
The contact angle with respect to the pigment ink having a surface tension of 30 to 50 degrees is preferable, and the contact angle with respect to the pigment ink having a surface tension of 30 to 45 mN / m is preferably 40 to 50 degrees. Thereby, the diameter of the ink dot when using the pigment ink can be further increased.

The contact angle can be determined by measuring the surface tension of the ink jet recording medium at 30 ° C. in an atmosphere of 25 ° C. and 50% RH.
15 μl of a pigment ink of ˜45 mN / m is gently dropped, and the contact angle 0.5 seconds after the contact is measured by using a commercially available contact angle meter.

In the invention according to claim 1, it is preferable that the surface layer contains an inorganic pigment. As a result, the ink absorption speed can be further improved, the printing speed can be further increased, and the circularity of the ink dot diameter can be further satisfied.

In the invention according to claim 1, it is preferable that the surface layer contains one or more kinds of silicon-based emulsions. As a result, the ink dot diameter can be increased. Further, the occurrence of cracks in the inkjet recording medium can be suppressed, and the production efficiency of the inkjet recording medium can be improved. Furthermore, it is easier to adjust the contact angle to the pigment ink having a surface tension of 30 to 45 mN / m to 30 to 50 degrees, which is preferable.

The silicone-based emulsion used in the present invention represents various silicone oils stably dispersed in an aqueous medium. The silicone oil may be so-called straight silicone oil or modified silicone oil. Examples of the silicone oil include dimethylpolysiloxane oil, amino-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, and polyether-modified silicone oil. An emulsion obtained by emulsifying an amino-modified silicone oil is particularly preferable.

Specific examples of the silicone emulsion used in the present invention include BY22-839 manufactured by Toray Dow Corning Silicone Co., Ltd., and silicon emulsions KM740, KM860, KM86 manufactured by Shin-Etsu Silicone Co., Ltd.
2 and the like.

In the invention according to claim 1, it is preferable that the surface layer contains at least one activator. As a result, the ink dot diameter can be increased. Furthermore, it is easier to adjust the contact angle to the pigment ink having a surface tension of 30 to 45 mN / m to 30 to 50 degrees, which is preferable.

The activator used in the present invention may be any of anion type, cation type and nonion type. Generally, in order to prevent aggregation with a compound in the ink absorbing layer having a cation charge, nonionic type or cation type is used. Is preferred, but the nonionic type is most preferred. For example, polyethylene glycol type, higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, higher aliphatic amine ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, glycerin fatty acid ester and the like can be mentioned. .

The activators used in the present invention are specifically Repon 2000HG, Repon 2000L, Repon CIB, Repon 101-H, Repon AM301 manufactured by Sanyo Chemical Co., Ltd., Nissan Anon BF manufactured by NOF Corporation, Nissan Anon LG,
Nissin Chemical's Surfynol CT111, Surfynol CT112, Surfynol GA, Olphin B, Takemoto Yushi's Pionin P-2310, Pyonin P-4
015, Pionein P-1525 and the like.

Further, the invention according to claim 1 is preferable, when the surface layer is used in combination with one or more kinds of silicon-based emulsion and one or more kinds of activator, because the ink dot diameter can be further increased. .

Further, it is easier to adjust the contact angle to the pigment ink having a surface tension of 30 to 45 mN / m to 30 to 50 degrees, which is preferable.

In the invention according to claim 1, at least the surface layer is preferably porous. As a result, the printing speed can be increased and the roundness of the ink dot diameter can be further satisfied.

The surface layer in the present invention refers to the layer on the outermost surface of the ink jet recording medium. Here, on the surface layer, for the purpose of improving the surface physical properties, when forming a thin film on the outermost surface for the purpose of cutting harmful light, etc., this thin film becomes the surface layer, in the present invention, the effect of the present invention If the range is obtained, the surface layer including the thin film will be the surface layer.

In the invention according to claim 1, it is preferable that the surface layer contains one or more kinds of thermoplastic resins. As a result, when the inkjet recording medium is heat-treated after printing with the pigment ink, the water resistance is improved and the photographic quality can be improved by setting the image quality to the silver salt photographic level.

Examples of the thermoplastic resin that can be used in the present invention include polycarbonate, polyacrylonitrile, polystyrene, polyacrylic acid, polymethacrylic acid, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, polyamide, Polyether,
These copolymers and these salts are mentioned. Among them, styrene-acrylic acid ester copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acrylic acid ester copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, SBR latex preferable. In addition, the thermoplastic resin may be used by mixing a plurality of polymers having different monomer compositions, particle sizes, and degrees of polymerization.

Points to be taken into consideration when selecting the thermoplastic resin are ink receptivity, glossiness after fixing by heating and pressurization, image fastness and the like. Regarding the ink receptivity, when the thermoplastic resin particles are small, the separation of the pigment particles and the ink solvent in the pigment ink becomes slow, which causes a substantial decrease in the absorption rate. On the other hand, if it is too large, it is not preferable from the viewpoint of the adhesiveness to the porous layer formed of the voids having the ink holding ability which are adjacent to each other when coated on the support and the film strength after coating and drying. Therefore, the preferable thermoplastic resin particle size is in the range of 0.05 to 10 μm, more preferably 0.1 to 5 μm.

The glass transition point Tg can be mentioned as a criterion for selecting the thermoplastic resin particles. When Tg is extremely low, for example, the coating drying temperature at the time of manufacturing the recording material is already higher than Tg, and the voids due to the thermoplastic resin particles for the ink solvent to pass through disappear. When Tg is extremely high, after inkjet recording with pigment ink,
A fixing operation at a high temperature is required for the melt film formation, and the load on the apparatus and the thermal stability of the support become problems. The preferable Tg of the thermoplastic resin particles is 50 to 150 ° C.

As the minimum film forming temperature (MFT),
It is preferably 50 to 150 ° C. The thermoplastic resin is preferably dispersed in an aqueous system from the viewpoint of environmental suitability,
In particular, an aqueous latex obtained by emulsion polymerization is preferable. At this time, the type obtained by emulsion polymerization using a nonionic dispersant as an emulsifier is a form that can be preferably used. From the viewpoint of odor and safety, the thermoplastic resin used preferably has a small amount of residual monomer components, and is preferably 3% by mass or less, more preferably 1% by mass or less, based on the solid content of the polymer. It is preferably 0.1% by mass or less.

In the case of the surface layer containing an inorganic pigment and a thermoplastic resin, the solid content mass ratio of thermoplastic resin / inorganic pigment can be selected from the range of 90/10 to 10/90, preferably 70/30 to 30 /. The range is 70, more preferably 60/40 to 40/60.

For the one or more thermoplastic resins and the one or more silicone-based emulsions used in the invention according to claim 9, the above-mentioned silicone-based emulsions and thermoplastic resins can be used.

In the invention according to claim 9, the surface layer is preferably a porous layer, and further, the surface layer preferably contains an inorganic pigment. As a result, the ink absorption speed can be further improved, the printing speed can be further increased, and the circularity of the ink dot diameter can be further satisfied.

Further, in the invention according to claim 9, 1 is formed on the surface layer.
It is preferred to contain one or more activators. This makes it possible to further increase the ink dot diameter when printing is performed using the pigment ink.

The lower layer of the surface layer of the ink jet recording medium of the present invention is preferably a porous layer containing inorganic fine particles.

The lower layer of the surface layer of the inkjet recording medium refers to a layer immediately below the surface layer of the inkjet recording medium. As a result, the circularity of the ink dot diameter becomes more satisfactory, the ink absorption speed is further improved, and the printing speed can be further increased.

The ink jet recording medium of the present invention can be used as any of dye inks, pigment inks, water-based inks, oil-based inks and hot melt inks, but it is more suitable for water-based dye inks and water-based pigment inks. When used, the ink dot diameter can be increased.

The present invention has a surface tension of 30 to 45 mN / m.
The surface tension of the pigment ink is determined by measuring the pigment ink at 25 ° C. by using a commercially available surface tensiometer. The commercially available surface tension meter is a CBVP type surface tension meter (Kyowa Kagaku Co., Ltd.).
Is mentioned.

As the colorant used in the ink, water-soluble dyes such as acid dyes, direct dyes, reactive dyes, disperse dyes and pigments can be used.

The pigment ink is particularly preferable from the viewpoint of image storability. As the pigment used in the pigment ink, an insoluble pigment, an organic pigment such as a lake pigment, and carbon black can be preferably used.

The insoluble pigment is not particularly limited, but for example, azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine. ,
Thiazine, dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferable.

Specific pigments that can be preferably used include the following pigments. Examples of magenta or red pigments 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 15,
C. I. Pigment Red 16, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1,
C. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123,
C. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I.
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 orange or yellow pigments include C.I. I. Pigment Orange 31, C.I.
I. Pigment Orange 43, C.I. I. Pigment Yellow 12, C.I. 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 9
4, C.I. I. Pigment Yellow 138 and the like.

As the pigment for green or cyan,
For example, C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 1
5: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.

A pigment dispersant may be used for these pigments if necessary, and examples of the pigment dispersant that can be used include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates and alkyl sulfonic acids. Salt, sulfosuccinate, naphthalene sulfonate, alkyl phosphate,
Activator such as polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide, or styrene, styrene derivative, vinyl Block copolymers of two or more monomers selected from naphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, random copolymers Mention may be made of polymers and their salts.

As a method for dispersing the pigment, various dispersing machines 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 can. Also,
It is also preferable to use a centrifugal separator and a filter for the purpose of removing coarse particles of the pigment dispersion.

The average particle size of the pigment particles in the pigment ink is selected in consideration of stability in the ink, image density, glossiness, light resistance, etc. In addition, in the image forming method of the present invention,
From the viewpoint of improving gloss and improving texture, it is preferable to appropriately select the particle size. In the present invention, the reason why the glossiness or texture is improved is not clear at this stage, but in the formed image, the pigment is in a state in which it is preferably dispersed in the film in which the thermoplastic resin is melted. Presumed to be related to. For the purpose of high-speed treatment, it is necessary to melt the thermoplastic resin into a film in a short time and further sufficiently disperse the pigment in the film. At this time, it is considered that the surface area of the pigment has a great influence, and therefore the average particle size has an optimum region.

The water-based ink composition, which is a preferred form of the pigment ink, is preferably used in combination with a water-soluble organic solvent. Examples of the water-soluble organic solvent that can be used in the present invention include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl). Alcohol, etc.), polyhydric alcohols (for example, 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,
Ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monoethyl ether Butyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.),
Amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine,
N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.),
Amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocycles (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1, 3-dimethyl-2-imidazolidinone etc.), sulfoxides (eg dimethyl sulfoxide etc.), sulfones (eg sulfolane etc.), urea, acetonitrile, acetone and the like. Examples of preferable water-soluble organic solvent include polyhydric alcohols. further,
It is particularly preferable to use a polyhydric alcohol and a polyhydric alcohol ether together.

The water-soluble organic solvent may be used alone or in combination of two or more. The total amount of the water-soluble organic solvent added to the ink is 5 to 60% by mass, preferably 10 to
It is 35 mass%.

The ink composition may contain various known additives, if necessary, depending on the purpose of improving ejection stability, compatibility with print heads and ink cartridges, storage stability, image storability, and other various properties. For example, a viscosity modifier, a surface tension modifier, a specific resistance modifier, a film-forming agent, a dispersant, a surfactant, a UV absorber, an antioxidant, an anti-fading agent, an anti-fouling agent, an anticorrosive agent, etc. are appropriately selected. For example, polystyrene, polyacrylic acid esters, polymethacrylic acid esters, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or copolymers thereof, urea resins, or Organic latex fine particles such as melamine resin, liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, etc. Droplet particles, various surfactants of cationic or nonionic, JP 57-74193,
UV absorbers described in JP-A-57-87988 and JP-A-62-261476, JP-A-57-74192 and 57.
-87989, 60-72785, 61-14.
6591, JP-A-1-95091 and 3-133.
No. 76, etc., anti-fading agent, JP-A-59-4
2993, 59-52689, 62-2800.
69, 61-242871, and JP-A-4-21.
Examples thereof include fluorescent whitening agents, pH adjusting agents such as sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and the like described in No. 9266.

The viscosity of the ink composition during flight is preferably 40 mPa · s or less, and more preferably 30 mPa · s or less. The surface tension of the ink composition during flight is preferably 20 mN / m or more,
More preferably, it is 30 to 45 mN / m.

Next, a method for manufacturing the ink jet recording medium of the present invention will be described. As a method for producing an inkjet recording medium, each of the constituent layers including a plurality of ink absorbing layers may be individually or simultaneously selected appropriately from known coating methods, coated on a support, and then dried. it can. As the coating method, for example, roll coating method, rod bar coating method, air knife coating method, spray coating method, curtain coating method,
Alternatively, US Pat. Nos. 2,761,419 and 2,7
A slide bead coating method using a hopper described in JP 61,791, an extrusion coating method and the like are preferably used.

When the slide bead coating method is used, the viscosity of each coating solution for simultaneous multi-layer coating is 5
The range is preferably from 100 to 100 mPa · s, more preferably from 10 to 50 mPa · s. When using the curtain coating method, the range of 5 to 1200 mPa · s is preferable, and the range of 25 to 500 mPa is more preferable.
・ S range.

The viscosity of the coating solution at 15 ° C. is preferably 100 mPa · s or more, 100 to 30,
000 mPa · s is more preferable, still more preferably 3,000 to 30,000 mPa · s, and most preferably 10,000 to 30,000 mPa · s.

As a coating and drying method, the coating liquid is 3 times.
It is preferable that after the simultaneous multilayer coating is performed by heating to 0 ° C. or higher, the temperature of the formed coating film is once cooled to 1 to 15 ° C. and dried at 10 ° C. or higher. During preparation of the coating solution, during coating and during drying, it is preferable to prepare, coat and dry the coating solution at a temperature not higher than Tg of the thermoplastic resin so that the thermoplastic resin contained in the surface layer does not form a film. More preferably,
As the drying conditions, a wet bulb temperature of 5 to 50 ° C. and a film surface temperature of 10
It is carried out under the condition of a temperature range of 50 ° C. In addition, as a cooling method immediately after coating, it is preferable to use a horizontal setting method from the viewpoint of uniformity of the formed coating film.

The method of supplying the curing agent is not particularly limited, but for example, a method of applying a solution containing the curing agent after forming the ink absorbing layer, or spraying the solution containing the curing agent onto the surface of the recording medium on which the ink absorbing layer has been formed. The method of spraying can be appropriately selected and used.

The heating conditions are not particularly limited as long as they are 35 ° C. or higher and 24 hours or longer, but preferable examples are, for example, 36 ° C. for 4 weeks, 40 ° C. for 2 weeks, or 55 ° C.
It's been 3 days. By performing this heat treatment, the curing reaction of the water-soluble binder or the crystallization of the water-soluble binder can be promoted, and as a result, preferable ink absorbency can be achieved.

Next, the ink jet recording method of the present invention will be described. An inkjet image is obtained by recording an image on a recording medium with an inkjet printer.

The invention according to claim 15 is characterized in that, as an ink jet recording method, the thermoplastic resin contained in the surface layer is melted or formed into a film by heating the recorded ink jet recording medium.

The heat treatment is carried out for the purpose of improving the image quality such as texture, gloss and the presence or absence of bronze, and improving the rubbing property and water resistance by melting or forming a film of the thermoplastic resin in the recording medium. In the heat treatment, it is desirable to apply the amount of heat necessary for almost completely melting or forming a film of the thermoplastic resin in the recording medium. On the other hand, in order to shorten the treatment time, the heat treatment should be performed in a short time. Is desirable,
The melting or film-forming treatment of the thermoplastic resin does not have to be completed as long as the image quality is not substantially different.

In order to apply the necessary amount of heat in a short time,
It is desirable to heat with a heat source as high as possible, but if the temperature is excessively high, the support may be damaged, severe curling may occur, or the image surface may be roughened or the heating roller may be contaminated. A range is preferred,
The range of 100 to 150 ° C. is more preferable.

The heating method may be performed by a heater built in the printer or by another heater. The use of a heating roller as the heating means is suitable for preventing the occurrence of unevenness and for performing a continuous process in a small space. In addition, it is cost-effective to use a heat fixing device for electrophotography. For example, a method of heating and pressing by passing a recording medium between a heating roller having a built-in heating element and a pressure roller, a method of heat-treating the recording medium by sandwiching it between two heating rollers, or a pair of heating rollers. There is a method of providing a fixing belt between them and performing heat treatment.

[0122]

The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 << Preparation of Inkjet Recording Medium >> An inkjet recording medium was prepared according to the following procedure.

[Preparation of Inorganic Fine Particle Dispersion] (Preparation of Silica Dispersion-1) 125 kg of vapor phase method silica (Aerosil Japan Co., Ltd .: A50) having an average primary particle size of about 0.03 μm was mixed with Mitamura. Jet stream inductor mixer TDS manufactured by Riken Industry Co., Ltd.
Using, was suction-dispersed in 215 L of pure water whose pH was adjusted to 2.5 with nitric acid at room temperature, and then a dispersion having a solid content concentration of 40 mass / volume% was finished to prepare a silica dispersion-1.

(Preparation of Silica Dispersion Liquid-2) 0.56 kg of the cationic polymer (P-1) was dissolved in 27.2 kg of ion-exchanged water to obtain 63.0 L of the above silica dispersion liquid-1.
Was added with stirring, and then 6% aqueous boric acid solution (p
H = 6.5) 8.8 L was added, and 1 g of a defoaming agent SN381 (manufactured by San Nopco Ltd.) was added. This mixed solution
After adjusting the pH to 4.4 with a 6% aqueous nitric acid solution, the dispersion was dispersed with a high pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd., and the total amount was adjusted to 99.7 L with pure water to prepare a silica dispersion liquid-2.

[0126]

[Chemical 1]

(Preparation of Silica Dispersion Liquid-3) 125 kg of vapor phase method silica (QS-20 manufactured by Tokuyama Corp.) having an average primary particle diameter of about 0.012 μm is jet stream manufactured by Mitamura Riken Kogyo Co., Ltd.・ Inductor mixer TD
After S was dispersed by suction in 620 L of pure water whose pH was adjusted to 2.5 with nitric acid at room temperature, the total amount was 694 L with pure water.
After that, a silica dispersion liquid-3 was prepared.

(Preparation of Silica Dispersion Liquid-4) 1.14 kg of the above-mentioned cationic polymer (P-1), ethanol 2.2.
An aqueous solution containing 1.5 L of L and n-propanol (pH =
2.3) In 18 L, 6 of the above-prepared silica dispersion liquid-3
9.4 L was added with stirring, then boric acid 260
7.0 L of an aqueous solution containing g and 230 g of borax was added, and 1 g of an antifoaming agent SN381 (manufactured by San Nopco Ltd.) was added. This mixed liquid was dispersed with a high pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd., and the total amount was adjusted to 97 L with pure water to prepare a silica dispersion liquid-4.

[Preparation of Thermoplastic Resin Coating Liquid] (Preparation of Thermoplastic Resin Coating Liquid 1) Styrene-acrylic latex polymer (Tg 78 ° C., average particle size 0.3 μm, emulsion polymerized by using a nonionic surfactant as an emulsifier). The solid content concentration of 40%) was adjusted to pH 4.7 with a 6% nitric acid aqueous solution, and this was used as a thermoplastic resin coating liquid 1.

(Preparation of Thermoplastic Resin Coating Liquid 2) Methacrylic acid ester-acrylic acid ester latex polymer (T
g73 ° C., average particle size 0.2 μm, solid content concentration 30%) was adjusted to pH 4.5 with 6% nitric acid aqueous solution, and this was used as a thermoplastic resin coating liquid 2.

(Preparation of Thermoplastic Resin Coating Liquid 3) Acrylic latex polymer (Tg 65 ° C., average particle size 0.3 μm, emulsion polymerized by using cationic surfactant as emulsifier)
The solid content concentration 20%) was adjusted to pH 4.5 with a 6% nitric acid aqueous solution, and this was used as a thermoplastic resin coating liquid 3.

[Preparation of each coating liquid] After preparing each coating liquid as described below, each coating liquid was put into a commercially available filter (TCP10 or TCP30 manufactured by Toyo Roshi Kaisha, Ltd.).
Filtered.

(Preparation of Lower Layer Coating Liquid 1) While stirring at 40 ° C., to 710 ml of the above-prepared silica dispersion liquid-2,
The following additives were sequentially mixed to prepare Lower Layer Coating Liquid 1.

[0134]   Polyvinyl alcohol (Kuraray Industry Co., Ltd .: PVA203)     10% aqueous solution of 3 ml   Polyvinyl alcohol (Kuraray Industry Co., Ltd .: PVA235) 4.8% and     Polyvinyl alcohol (Kuraray Industry Co., Ltd .: PVA245) 1.84%     Aqueous solution containing 273 ml The total volume was adjusted to 1000 ml with pure water.

(Preparation of Lower Layer Coating Liquid 2) While stirring at 40 ° C., to 710 ml of the above-prepared silica dispersion liquid-4,
The following additives were sequentially mixed to prepare Lower Layer Coating Liquid 2.

[0136]   Polyvinyl alcohol (Kuraray Industry Co., Ltd .: PVA203)     10% aqueous solution of 3 ml   Polyvinyl alcohol (Kuraray Industry Co., Ltd .: PVA235) 4.8% and     Polyvinyl alcohol (Kuraray Industry Co., Ltd .: PVA245) 1.84%     Aqueous solution containing 273 ml The total volume was adjusted to 1000 ml with pure water.

(Preparation of Upper Layer Coating Liquid 1) The lower layer coating liquid 1 prepared above was used as the upper layer coating liquid 1.

(Preparation of Upper Layer Coating Liquid 2) The thermoplastic resin coating liquid 1 prepared above was used as the upper layer coating liquid 2.

(Preparation of Upper Layer Coating Solution 3) The upper layer coating solution 1 was added with Activator 1 (Repon 2000HG) at 13.3 m per liter.
It was added at a ratio of 1 to obtain an upper layer coating liquid 3.

(Preparation of Upper Layer Coating Liquid 4) Silicone emulsion 1 (BY22-839) was added to Upper Layer Coating Liquid 1 at a ratio of 18.2 ml per liter to prepare Upper Layer Coating Liquid 4.

(Preparation of Upper Layer Coating Liquid 5) The upper layer coating liquid 2 was charged with Activator 1 (Repon 2000HG) at 13.3 m per liter.
It was added at a ratio of 1 to obtain an upper layer coating liquid 5.

(Preparation of Upper Layer Coating Liquid 6) Silicone emulsion 1 (BY22-839) was added to Upper Layer Coating Liquid 2 at a rate of 18.2 ml per liter to prepare Upper Layer Coating Liquid 6.

(Preparation of Upper Layer Coating Liquid 7) The upper layer coating liquid 1 and the thermoplastic resin coating liquid 2 were mixed so that the solid content ratio of the thermoplastic resin and the inorganic pigment was 4: 6, and then 43 ° C.
After adding pure water so that the viscosity of the solution becomes 45 mPa · s, the silicone-based emulsion 1 (BY22-839) was added at a ratio of 18.2 ml per liter to prepare the upper coating solution 7
And

(Preparation of Upper Layer Coating Liquid 8) The upper layer coating liquid 2 and the thermoplastic resin coating liquid 2 were mixed so that the solid content ratio of the thermoplastic resin and the inorganic pigment was 4: 6, and then 43 ° C.
After adding pure water so that the viscosity of the solution becomes 45 mPa · s, the silicone-based emulsion 1 (BY22-839) was added at a ratio of 18.2 ml per liter to prepare the upper layer coating solution 8
And

(Preparation of Upper Layer Coating Liquid 9) The upper layer coating liquid 2 and the thermoplastic resin coating liquid 2 were mixed so that the solid content ratio of the thermoplastic resin and the inorganic pigment was 5: 5, and then 43 ° C.
After adding pure water so that the viscosity in Table 1 was 45 mPa · s, Silicone emulsion 2 (KM740) was added at a rate of 10.5 ml per liter to prepare an upper layer coating liquid 9.

(Preparation of Upper Layer Coating Liquid 10) The upper layer coating liquid 2 and the thermoplastic resin coating liquid 2 were mixed so that the solid content ratio of the thermoplastic resin and the inorganic pigment was 4: 6, and then 43
After adding pure water so that the viscosity at 45 ° C is 45 mPa · s, add 1 L of Silicone emulsion 3 (KM862).
6.7 ml was added to make an upper layer coating solution 10.

(Preparation of Upper Layer Coating Liquid 11) Upper layer coating liquid 2 and thermoplastic resin coating liquid 2 were mixed so that the solid content ratio of the thermoplastic resin and the inorganic pigment was 4: 6, and then 43
Add pure water so that the viscosity at 45 ° C is 45 mPa · s, and then add 1 activator 1 (Repon 2000HG) per 1 L.
It was added at a rate of 3.3 ml to obtain an upper layer coating liquid 11.

(Preparation of Upper Layer Coating Liquid 12) The upper layer coating liquid 2 and the thermoplastic resin coating liquid 2 were mixed so that the solid content ratio of the thermoplastic resin and the inorganic pigment was 6: 4, and then 43
Pure water was added so that the viscosity at 45 ° C. was 45 mPa · s, and the upper layer coating solution 12 was obtained.

(Preparation of Upper Layer Coating Liquid 13) The upper layer coating liquid 2 and the thermoplastic resin coating liquid 3 were mixed so that the solid content ratio of the thermoplastic resin and the inorganic pigment was 4: 6, and then 43
Pure water was added so that the viscosity at 45 ° C. was 45 mPa · s, and the upper layer coating liquid 13 was obtained.

(Preparation of Upper Layer Coating Liquid 14) The upper layer coating liquid 2 and the thermoplastic resin coating liquid 2 were mixed so that the solid content ratio of the thermoplastic resin and the inorganic pigment was 5: 5, and then 43
Pure water was added so that the viscosity at 45 ° C. was 45 mPa · s, and the upper layer coating liquid 14 was obtained.

(Preparation of upper layer coating liquid 15) 100 parts of alumina hydrate (Cataloid AS-3, manufactured by Catalyst Kasei), polyvinyl alcohol (PVA11, manufactured by Kuraray Industries Co., Ltd.)
7) Disperse 30 parts to prepare an alumina solution, to which silicon-based emulsion 1 (BY22-839) was added at a ratio of 18.2 ml per liter to prepare an upper coating solution 1
It was set to 5.

[Preparation of Inkjet Recording Medium] (Preparation of Sample 1) A paper support having both sides coated with polyethylene (also referred to as RC paper, having a thickness of 220 μm, and polyethylene in the ink absorption layer surface is 13 mass% with respect to polyethylene). % Of anatase-type titanium oxide) in order from the support side, the lower layer coating solution 1 as the first layer and the upper layer coating solution 1 as the second layer were simultaneously coated and dried in two layers using a slide hopper. . Each coating solution was heated to 40 ° C. and applied, and immediately after the application, it was cooled for 20 seconds in a cooling zone kept at 0 ° C., and then 6 ° C. with 25 ° C. air (15% relative humidity).
0 seconds, 45 ° C wind (25% relative humidity) for 60 seconds,
Sequential drying with 50 ° C. air (relative humidity 25%) for 60 seconds, and humidity control in an atmosphere of 20 to 25 ° C. and relative humidity of 40 to 60 ° C. for 2 minutes, and then winding the sample, sample 1 It was made.

(Preparation of Sample 2) A sample 2 was prepared in the same procedure as the preparation of the sample 1 except that the upper layer coating liquid 1 was changed to the upper layer coating liquid 2.

(Preparation of Sample 3) Sample 3 was prepared in the same procedure as in preparation of Sample 1 except that the upper layer coating liquid 1 was changed to the upper layer coating liquid 3.

(Preparation of Sample 4) Sample 4 was prepared in the same procedure as the preparation of Sample 1 except that the upper layer coating liquid 1 was changed to the upper layer coating liquid 4.

(Preparation of Sample 5) Sample 5 was prepared in the same procedure as in preparation of Sample 1 except that the upper layer coating liquid 1 was changed to the upper layer coating liquid 5.

(Preparation of Sample 6) Sample 6 was prepared in the same procedure as in preparation of Sample 1 above, except that the upper layer coating liquid 1 was changed to the upper layer coating liquid 6.

(Preparation of Sample 7) A sample 7 was prepared in the same procedure as in preparation of the sample 1 except that the upper layer coating liquid 1 was changed to the upper layer coating liquid 7.

(Preparation of Sample 8) In preparation of Sample 1 described above, the lower layer coating liquid 1 was changed to the lower layer coating liquid 2, and the upper layer coating liquid 1 was prepared.
Sample 8 was prepared in the same procedure except that the coating liquid 8 was changed to

(Preparation of Sample 9) A sample 9 was prepared in the same procedure as the preparation of the sample 8 except that the upper layer coating liquid 8 was changed to the upper layer coating liquid 9.

(Preparation of Sample 10) A sample 10 was prepared in the same procedure as the preparation of the sample 8 except that the upper layer coating liquid 8 was changed to the upper layer coating liquid 10.

(Preparation of Sample 11) A sample 11 was prepared in the same procedure as in preparation of the sample 8 except that the upper layer coating liquid 8 was changed to the upper layer coating liquid 11.

(Preparation of Sample 12) In preparation of Sample 8 above, the upper layer coating liquid 8 was changed to the upper layer coating liquid 12, and
After the application of the upper layer coating liquid 12, the activator 1 (repon 20
00HG) aqueous solution was overcoated to give a coating amount of 0.8 g / m ²
Was produced.

(Preparation of Sample 13) In the preparation of Sample 8, the upper layer coating liquid 8 was changed to the upper layer coating liquid 13, and
After the application of the upper layer coating solution 13 was completed, Sample 13 was prepared by the same procedure except that the activator 2 (Nissan Anon BF) aqueous solution was overcoated to a coating amount of 0.3 g / m ^2.
Was produced.

(Preparation of Sample 14) In preparation of Sample 8 above, the upper layer coating liquid 8 was changed to the upper layer coating liquid 14, and
After the coating of the upper layer coating liquid 14 was completed, the sample 14 was prepared in the same procedure except that the aqueous solution of the activator 3 (Pionine P-2310) was overcoated so that the coating amount was 0.3 g / m ² .

(Preparation of Sample 15) A sample 15 was prepared in the same procedure as the preparation of the sample 8 except that the upper layer coating liquid 8 was changed to the upper layer coating liquid 15.

(Preparation of Sample 16) Sample 16 was prepared in the same procedure as in Preparation of Sample 8 except that the support was changed to a water absorbent paper support (middle paper for coated paper, thickness 165 μm, referred to as paper support). Was produced.

(Preparation of Sample 17) Sample 17 was prepared in the same procedure as the preparation of Sample 8 except that the support was changed to a film support made of white polyethylene terephthalate (thickness 100 μm, abbreviated as PET).

Details of the structures of Samples 1 to 17 are shown in Table 1.
The contact angles of Samples 1 to 17 were 25 ° C. and 50% RH, and 15 μl of yellow dark ink (surface tension; 36 mN / m) described in Example 2 described later was gently dropped onto each sample. It is a value obtained by measuring the contact angle after 0.5 seconds from contact with an automatic contact angle meter (DAC-VZ).

[0170]

[Table 1]

<< Evaluation of Each Characteristic of Inkjet Recording Medium >> (Evaluation of Crack Failure) 0.3 m ² of the coated surface of each of the prepared Samples 1 to 17 was completely dried and heated to 55 ° C. for 3 days, and 3 After allowing to cool for a day, the surface on the ink absorbing layer side was visually inspected and whether or not fine cracks had occurred was observed using a magnifying glass and evaluated as follows.

5: No cracks were observed at all 4: Very fine cracks were generated at 1 to 5 places, but could not be visually observed 3: There were 6 or more fine cracks were visually observed, but could be visually observed No 2: Fine cracks were generated on one side, and visually observable 1: Cracks were connected in some places to form a large crack. The evaluation results obtained above are shown in Table 2.

[0173]

[Table 2]

Example 2 << Preparation of Ink >> [Preparation of Aqueous Pigment Ink] (Preparation of Pigment Dispersion) <Preparation of Yellow Pigment Dispersion 1> C.I. I. Pigment Yellow 74 20% by mass Styrene-acrylic acid copolymer (molecular weight 10,000, acid value 120) 12% by mass Diethylene glycol 15% by mass Ion-exchanged water 53% by mass Mixing the above additives, 0.3 mm zirconia beads Was dispersed using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with 60% by volume to obtain a yellow pigment dispersion 1. The average particle size of the obtained yellow pigment was 112 nm.

<Preparation of Magenta Pigment Dispersion 1> C.I. I. Pigment Red 122 25% by mass John Cryl 61 (acrylic-styrene resin, manufactured by Johnson Co.) Solid content 18% by mass Diethylene glycol 15% by mass Ion-exchanged water 42% by mass Mixing the above additives, 0.3 mm zirconia beads Was dispersed using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with 60% by volume to obtain a magenta pigment dispersion 1. The average particle size of the obtained magenta pigment was 105 nm.

<Preparation of Cyan Pigment Dispersion 1> C.I. I. Pigment Blue 15: 3 25% by mass John Cryl 61 (acrylic-styrene resin, manufactured by Johnson Co.) 15% by mass as solid content Glycerin 10% by mass Ion-exchanged water 50% by mass Add each of the above additives to obtain 0.3 mm Cyan pigment dispersion 1 was obtained by dispersing using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with zirconia beads at a volume ratio of 60%. The average particle size of the obtained cyan pigment is 87.
was nm.

<Preparation of Black Pigment Dispersion 1> Carbon black 20% by mass Styrene-acrylic acid copolymer (molecular weight 7,000, acid value 150) 10% by mass Glycerin 10% by mass Ion-exchanged water 60% by mass Each of the above additions The agents were mixed and dispersed using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co.) filled with 0.3 mm zirconia beads at a volume ratio of 60% to obtain a black pigment dispersion 1. The average particle size of the obtained black pigment was 75 nm.

(Preparation of Pigment Ink) <Preparation of Yellow Dark Ink> Yellow Pigment Dispersion 1 15% by mass Ethylene glycol 20% by mass Diethylene glycol 10% by mass Surfactant (Surfynol 465, Nissin Chemical Industry Co., Ltd.) 0.1% by mass % Ion-exchanged water 54.9 mass% The above compositions were mixed, stirred, and filtered through a 1 μm filter to prepare a yellow dark ink which is the aqueous pigment ink of the present invention. The average particle size of the pigment in the ink is 120 nm
And the surface tension γ was 36 mN / m.

<Preparation of Yellow Light Ink> Yellow Pigment Dispersion 1 3% by mass Ethylene glycol 25% by mass Diethylene glycol 10% by mass Surfactant (Surfynol 465, Nissin Chemical Industry Co., Ltd.) 0.1% by mass ion-exchanged water 61. 9% by mass or more of each composition was mixed, stirred, and filtered with a 1 μm filter to prepare a yellow light ink which is the aqueous pigment ink of the present invention. The average particle size of the pigment in the ink is 118 nm
And the surface tension γ was 37 mN / m.

<Preparation of Magenta Dark Ink> Magenta Pigment Dispersion 1 15% by mass Ethylene glycol 20% by mass Diethylene glycol 10% by mass Surfactant (Surfynol 465, Nisshin Chemical Industry Co., Ltd.) 0.1% by mass ion-exchanged water 54. 9% by mass or more of each composition was mixed, stirred, and filtered with a 1 μm filter to prepare a magenta dark ink which is the aqueous pigment ink of the present invention. The average particle size of the pigment in the ink is 113 nm
And the surface tension γ was 35 mN / m.

<Preparation of Magenta Light Ink> Magenta Pigment Dispersion 1 3% by mass Ethylene glycol 25% by mass Diethylene glycol 10% by mass Surfactant (Surfynol 465, Nissin Chemical Industry Co., Ltd.) 0.1% by mass ion-exchanged water 61. 9% by mass or more of each composition was mixed, stirred, and filtered with a 1 μm filter to prepare a magenta light ink which is the aqueous pigment ink of the present invention. The average particle size of the pigment in the ink is 110 nm
And the surface tension γ was 37 mN / m.

<Preparation of Cyan Dark Ink> Cyan Pigment Dispersion 1 10% by mass Ethylene glycol 20% by mass Diethylene glycol 10% by mass Surfactant (Surfynol 465 Nissin Chemical Industry Co., Ltd.) 0.1% by mass Ion-exchanged water 59. 9% by mass or more of each composition was mixed, stirred, and filtered with a 1 μm filter to prepare cyan dark ink which is the aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 95 nm, and the surface tension γ was 36 mN / m.

<Preparation of Cyan Light Ink> Cyan Pigment Dispersion 12 2% by mass Ethylene glycol 25% by mass Diethylene glycol 10% by mass Surfactant (Surfynol 465 Nisshin Chemical Industry Co., Ltd.) 0.2% by mass Ion-exchanged water 62. 8% by mass or more of each composition was mixed, stirred, and filtered with a 1 μm filter to prepare a cyan light ink which is the aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 92 nm, and the surface tension γ was 33 mN / m.

<Preparation of Black Dark Ink> Black Pigment Dispersion 1 10% by mass Ethylene glycol 20% by mass Diethylene glycol 10% by mass Surfactant (Surfynol 465 Nisshin Chemical Industry Co., Ltd.) 0.1% by mass ion-exchanged water 59. 9% by mass or more of each composition was mixed, stirred, and filtered with a 1 μm filter to prepare a black dark ink which is the aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 85 nm, and the surface tension γ was 35 mN / m.

<Preparation of Black Light Ink> Black Pigment Dispersion 12 2% by mass Ethylene glycol 25% by mass Diethylene glycol 10% by mass Surfactant (Surfynol 465, Nissin Chemical Industry Co., Ltd.) 0.1% by mass ion-exchanged water 62. 9% by mass or more of each composition was mixed, stirred, and filtered with a 1 μm filter to prepare a black light ink which is the aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 89 nm, and the surface tension γ was 36 mN / m.

<< Preparation of Inkjet Image >> Samples 1 to 1
Inkjet image 1 using the above-prepared ink
~ 17 were created.

The inkjet printer used was an inkjet printer MC-2000 (manufactured by Seiko Epson Corporation). As the printed image, a test chart was printed in which bands of 1 cm wide yellow dark ink, yellow light ink, magenta dark ink, magenta light ink, cyan dark ink, cyan light ink, black dark ink, and black light ink were drawn.

<< Evaluation of Output Image >> The following evaluations were performed on the images 1 to 17 output as described above.

(Evaluation of Solid Uniformity) The solid uniformity of each printed ink was visually evaluated on a scale of 5 according to the criteria shown below.

5: No unevenness at all 4: Slight unevenness is recognized, but solid printing does not pose any problem in practice Level 3: Although unevenness is clearly visible in solid printing,
Almost no problem in actual printing Level 2: Color unevenness is recognized and practically unacceptable Level 1: Totally unacceptable level (Evaluation of ink dot shape) Dot shape for each dot of each printed ink The magnified evaluation was performed with a magnifying glass, and the character quality was evaluated according to the criteria described below.

4: There is no feeling of roughness, and the dot shape is a perfect circle. 3: A slight feeling of roughness is observed, but the dot shape is a perfect circle. 2: A feeling of roughness is recognized, and the dot shape is slightly disturbed. 1: The color bleeding was large and the dot shape was bad (evaluation of color bleeding). The color bleeding related to the ink absorption speed was evaluated. The evaluation was performed by visually observing the occurrence of color bleeding at the boundary between the white background and each color on the printed band-shaped test chart of each ink, and the evaluation was performed according to the following criteria.

4: Almost no color bleeding was observed at the boundary of all colors 3: 1, color bleeding was observed slightly at the boundary with 2 colors 2: color bleeding at the boundary was observed in several colors Table 1 shows the evaluation results obtained by the above-mentioned observations in which the number of observed colors was 1: several colors, and the boundary color bleeding was considerably severe.

[0193]

[Table 3]

As is clear from Table 3, the ink jet recording medium of the present invention was found to be excellent in solid uniformity because the ink dot shape becomes large when printed with a pigment ink. It was also found that the ink absorption speed and the circularity of the ink dot shape were satisfactory.

Example 3 Sample 1 on which an inkjet image was prepared in Example 2
Then, heat treatment was performed using a heating roller having a surface temperature of 120 ° C. to dissolve the thermoplastic resin contained in the inkjet recording medium. << Evaluation of Image >> The following evaluations were performed on the heat-treated sample.

(Visual Evaluation of Image Quality) The output test chart and portrait portrait image were mainly used, and 20 persons were arbitrarily selected as image quality evaluation panelists to visually evaluate the image quality. For each sample to be evaluated, the same image is printed on a conventional color paper (Konica Color Paper T
It was evaluated by comparison with a photographic image reference sample printed on the ypeQAA7 gloss type).

The evaluation was performed by aggregating the number of the 20 panelists who were judged to be equivalent to the photographic image reference sample, and rating the ranks 1 to 5 shown below.

5: 17 or more persons evaluated to be equivalent to the photographic image reference sample 4: 14 to 16 persons evaluated to be equivalent to the photographic image reference sample 3: Equal to the photographic image reference sample The number of people evaluated to be 10 to 13 2: The number of people evaluated to be equivalent to the photographic image reference sample is 6 to 9 1: The number of people evaluated to be equivalent to the photographic image reference sample is less than 6 ( Evaluation) Each formed image was immersed in water at 20 ° C. for 1 hour, allowed to stand for 2 days, and naturally dried to observe the occurrence of film peeling. This operation was sequentially repeated, and judgment was made according to the criteria described below.

Image film peeling does not occur after repeated dipping up to 3: 5 times. Image film peeling occurs after repeated dipping 2 to 5 times. Image film peeling occurs during 1st dipping. Peeling occurred

[0200]

[Table 4]

As is clear from Table 4, the ink jet recording medium containing the thermoplastic resin has the image quality of an ink jet image of a silver salt photographic level by dissolving the thermoplastic resin, and is further excellent in water resistance. There was found.

[0202]

According to the present invention, the circularity of the ink dot diameter when printed with a pigment ink is prevented, which prevents a decrease in solid uniformity due to the reduction of the ink dot diameter when printed with a pigment ink. An inkjet recording medium and an inkjet recording method satisfying at least one of satisfying, increasing the printing speed, improving the durability of the recording medium, and improving the print quality can be provided.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Makoto Kaga             Konica Stock Market, 1 Sakura-cho, Hino City, Tokyo             In-house (72) Inventor Teruyuki Fukuda             Konica Stock Market, 1 Sakura-cho, Hino City, Tokyo             In-house F-term (reference) 2C056 EA04 EA13 FC01 FC06                 2H086 BA05 BA15 BA16 BA31 BA33                       BA36 BA41 BA55 BA60

Claims (15)

[Claims] 1. An inkjet recording medium having one or more porous layers on a support, the surface tension of which is 30 to 4.
The contact angle for a pigment ink of 5 mN / m is 30 to 5
An inkjet recording medium that is 0 degree. 2. The ink jet recording medium according to claim 1, wherein the surface layer contains at least one thermoplastic resin. 3. The ink jet recording medium according to claim 1, wherein at least the surface layer is a porous layer. 4. The ink jet recording medium according to claim 3, wherein the surface layer contains an inorganic pigment. 5. The ink jet recording medium according to claim 3, wherein the surface layer contains one or more kinds of silicon-based emulsions. 6. The ink jet recording medium according to claim 3, wherein the surface layer contains one or more activators. 7. The ink jet recording medium according to claim 3, further comprising a porous layer containing an inorganic pigment as a lower layer of the surface layer. 8. The ink jet recording medium according to claim 3, wherein the surface layer contains one or more kinds of thermoplastic resins. 9. An ink jet recording medium having one or more porous layers on a support, wherein at least one surface layer is provided.
An inkjet recording medium containing one or more thermoplastic resins and one or more silicone emulsions. 10. The ink jet recording medium according to claim 9, wherein the surface layer is a porous layer. 11. The inkjet recording medium according to claim 9, wherein the surface layer contains an inorganic pigment. 12. The inkjet recording medium according to claim 9, wherein the surface layer contains at least one activator. 13. A porous layer containing an inorganic pigment as a lower layer of the surface layer, wherein the porous layer contains an inorganic pigment.
The inkjet recording medium according to any one of 1. 14. The ink jet recording medium according to claim 9, wherein the contact angle with respect to the pigment ink having a surface tension of 30 to 45 mN / m is 30 to 50 degrees. 15. The ink-jet recording medium according to claim 2, after recording with a pigment ink, heat treatment is performed to melt or form a film of the thermoplastic resin. Inkjet recording method.