JP2003200649A - Inkjet recording paper for pigment ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink recording paper for a pigment ink, in which the difference between the glossiness of a printed part recorded with the pigment ink and that of a non-printed part is made smaller so as to eliminate uncomfortable feeling and with which an image excellent in scratch resistance. <P>SOLUTION: The outermost layer of the inkjet recording paper for the pigment ink is a porous layer containing water-insoluble organic particles, the SP value of which is 18.414 to 30.69 (MPa)<SP>1/2</SP>and which dissolves or swells in or with a water-soluble organic solvent having a boiling point of 120°C or higher. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording paper for pigment ink, and more particularly to an ink jet recording paper for pigment ink which is excellent in ink absorption and scratch resistance.

[0002]

2. Description of the Related Art In recent years, print quality has come to be comparable to that obtained by silver halide photography, with the rapid technological innovation of ink jet recording. The print quality obtained by inkjet recording mainly depends on three factors: printer, ink, and inkjet recording paper, but from the viewpoint of image quality, the recent technological innovations of the former two are remarkable and correspond to this. As a result, the importance of the quality of recording paper has increased significantly.

Ink jet recording papers are roughly classified into those in which a support itself such as paper is ink-absorbing and those in which an ink absorption layer is provided on the support.
Even in the former and a part of the latter, wrinkles are likely to occur in an image form when the support absorbs the ink solvent, and the coloring material dyed in the ink absorption layer gradually penetrates into the support during storage. It has a characteristic that the concentration is likely to decrease due to

On the other hand, the ink jet recording paper provided with the ink absorbing layer on the non-water-absorbing support has no characteristic of wrinkles and less decrease in density, so that it is possible to obtain high quality ink jet printing. is doing.

Generally, as the ink absorbing layer provided on the support, a swelling type ink absorbing layer and a void type ink absorbing layer are known.

The swelling type ink absorbing layer is substantially composed of a hydrophilic polymer such as gelatin, polyvinyl alcohol, polyvinylpyrrolidone or polyethylene oxide. The characteristics of the swelling type ink absorbing layer are that high glossiness can be obtained and that a large volume of ink can be absorbed within a range where the polymer can be swollen because a swelling polymer is used.

On the other hand, the void-type ink absorbing layer has several kinds of manufacturing methods, but a typical one is a layer composed of a small amount of hydrophilic polymer and a large amount of fine particles, and voids are formed between the fine particles. The ink is absorbed in the voids. The characteristics of the void-type ink absorbing layer are that the ink absorbing speed is fast, unevenness is less likely to occur during printing, and that both water resistance can be satisfied at the same time, and that the surface is apparently dry immediately after printing.

The recording paper of the swelling type ink absorbing layer and the recording paper of the void type ink absorbing layer are selected according to the application.
From the viewpoint of image quality obtained, it is preferable that the void-type ink absorbing layer has a high ink absorbing ability and a high drying property.

On the other hand, with regard to the type of ink, dye-based ink has often been used mainly for photographic image quality from the viewpoint of image quality. However, in the dye ink, since dye molecules are mainly dispersed in a molecular state and fixed in the ink receiving layer, the light resistance and the bleeding prevention of the image over time are not always sufficient. Is preferred.

That is, when the dye ink is used, the dye molecules are fixed to the ink absorbing layer in a substantially molecular state, but depending on the dye molecules, the water solubility is high, so that sufficient fixability cannot be imparted. Bleeding may occur in the image over time. Further, the dye in the molecular state is easily affected by oxygen, and generally photobleaching is remarkably accelerated by the contribution of oxygen, so that there is a problem that the light resistance is insufficient.

On the other hand, when the pigment ink is used, the coloring material is fixed to the ink absorbing layer in the form of fine particles, but since the solubility is originally low, bleeding hardly occurs, and the influence of oxygen also affects the pigment particle surface. Since it only acts, the color fading speed of the dye is slow and the light resistance is excellent.

However, when recording with a pigment ink, the pigment particles usually have a secondary particle diameter of about 0.1 to 0.5 μm, and the ink absorbing layer has a pore diameter larger than this particle diameter. If not, the pigment ink will not be contained in the ink absorbing layer and will be fixed on the surface of the ink absorbing layer in an aggregated state. Fixing the pigment particles having the above particle size on the surface of the ink absorbing layer forms unevenness of this size on the surface of the ink absorbing layer, but since the pigment particle size is close to the wavelength of visible light, It is easy to cause scattering and has a great influence on the surface gloss.

The effect of this light scattering is also related to the type of pigment ink and the amount of ejected ink. For example, gloss is slightly reduced in the low-density area (area where dots do not overlap), and reverse in high-density area (area where dots overlap and pigment particles aggregate relatively uniformly in a wide area after drying). There is a case where the gloss is increased, a case where the gloss is decreased regardless of the density region, and a case where the surface is increased like a metallic gloss regardless of the density.

The cause of these glossiness differences is the particle size of the pigment particles, the easiness of aggregation of the pigment particles themselves, or other components contained in the pigment ink (for example, a polymer having a protective colloid property for the pigment particles). It is assumed that the change in glossiness in an imagewise manner in any case is extremely unfavorable for print quality.

Conventionally, recording is also performed using a pigment ink on so-called low gloss recording paper. In this case, the pore diameter forming the irregularities on the surface is relatively large, and at least a part of the pigment ink is taken into the pores, so that the change in gloss is reduced. However, in this recording paper, the support has no water resistance, wrinkles are generated in the printed portion, and the gloss is extremely low, so that it is hard to say that the image quality is photographic.

Further, when the pigment ink is used for the dye ink in which the color material printed as described above enters the voids of the recording paper, the pigment ink is exposed on the surface of the recording paper and is in a deposited state, so that it is resistant. It has a problem that the scratching property is deteriorated.

As a method of solving such a problem,
Although a method of performing a laminating process after recording an image is known, it has a drawback that the process is required after the image is formed, which is troublesome.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to reduce the difference in glossiness between a printed portion and a non-printed portion recorded with a pigment ink to eliminate a feeling of strangeness. Another object of the present invention is to provide an inkjet recording paper for pigment ink, which can provide an image having excellent scratch resistance.

[0019]

The above objects of the present invention have been achieved by the following constitutions.

1. SP value is 18.414-30.69
An ink jet for a pigment ink, having as a surface layer a porous layer containing water-insoluble organic particles which is (MPa) ^1/2 and is dissolved or swollen by a water-soluble organic solvent having a boiling point of 120 ° C. or higher. Recording sheet.

2. On a support, a first porous layer containing at least inorganic particles and a hydrophilic binder as main components, and SP
A second porous layer containing water-insoluble organic particles having a value of 18.414 to 30.69 (MPa) ^1/2 and dissolved or swollen by a water-soluble organic solvent having a boiling point of 120 ° C. or higher; An inkjet recording paper for pigment ink, which has an ink absorption layer sequentially provided with.

3. The average particle size of the organic particles is 5 to 100.
3. The inkjet recording paper for pigment ink according to the item 1 or 2, wherein the inkjet recording paper has a thickness of 1 nm.

The ink jet recording paper for pigment ink of the present invention (hereinafter, also referred to as the ink jet recording paper of the present invention or the recording paper of the present invention) needs to have a high ink absorption rate, and therefore at least the surface layer is porous. Although it has a layer, that is, a void layer, the morphology of voids can be confirmed by electron microscope observation. It is preferable that the voids are not isolated from each other but continuously connected to each other. As the definition of the void diameter in this case, for example, a measured value by a mercury porosimetry can be used.

In the void type recording paper, in many cases, the voids filled with fine particles are voids. Therefore, the void size can also be expressed from the size of the filled particles and the filling rate. In order to exhibit sufficient ink absorbency, the size of the fine particles preferably used in the present invention is 1n.
m-2 μm, more preferably 5 nm-1 μm.

After the ink is applied to the recording paper at the time of printing, the water in the ink gradually evaporates, but the water-soluble organic solvent evaporates slowly, and the ratio of the water-soluble organic solvent as the liquid remaining on the recording paper gradually increases. Get higher That is, these substances that are insoluble in water and soluble in these water-soluble organic solvents gradually start to dissolve as the ink dries. That is, when inkjet recording is performed using a recording paper containing organic particles insoluble in water, which is dissolved or swollen by the water-soluble organic solvent according to the present invention, some or all of the organic particles are dissolved after the ink is dried, Alternatively, the layer is softened by swelling and the ink pigment particles are completely or partially embedded in the surface layer, and as a result, unevenness due to the ink pigment particles is not formed, or an image in which unevenness is not noticeable is formed. as a result,
The difference in glossiness between the printed part and the non-printed part is reduced,
Further, an image having good scratch resistance can be obtained.

The present invention will be described in detail below. Claim 1
In the invention according to, the surface layer of the inkjet recording paper for pigment ink has an SP value of 18.414 to 30.69 (MP
a) ^1/2, and a boiling point to dissolve or swell by 120 ° C. or more water-soluble organic solvent, characterized in that it is a porous layer containing an insoluble organic particles in water.

In the present invention, SP (Solubility)
Parameter) is a solubility parameter and is a useful measure for predicting the solubility of a substance. The unit of SP value is represented by (MPa) ^1/2 and indicates the value at 25 ° C.

Regarding the SP value of the organic solvent, for example,
"POLYMER HANDBOOK" (J. Bran
drup et al., A Wiley-interscience
(CePublication), page IV-337, as well as various publications.

Examples of water-soluble organic solvents (representative SP values shown in parentheses) that can be used in the present invention are:
Alcohols (eg, butanol (23.3), isobutanol (21.5), secondary butanol (2
2.1), tertiary butanol (21.7), pentanol, hexanol, cyclohexanol (23.
3), benzyl alcohol (24.8), etc., polyhydric alcohols (for example, ethylene glycol (29.9),
Diethylene glycol (24.8), triethylene glycol (21.9), polyethylene glycol, propylene glycol (25.8), dipropylene glycol (20.5), polypropylene glycol, butylene glycol, hexanediol (21.1), Pentanediol, glycerin (33.8), hexanetriol, thiodiglycol, etc., alkyl ethers of polyhydric alcohols (for example, ethylene glycol monomethyl ether (23.3), ethylene glycol monoethyl ether (21.5), Ethylene glycol monobutyl ether, ethylene glycol dimethyl ether (17.
6), diethylene glycol monomethyl ether (2
3.3), diethylene glycol monoethyl ether,
Diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol monoethyl ether, triethylene glycol monomethyl ether,
Triethylene glycol monobutyl ether, triethylene glycol diethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, etc.), amine Kinds (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine,
N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine (25.2), diethylenetriamine, 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-). Examples thereof include imidazolidinone), sulfoxides (eg, dimethyl sulfoxide), sulfones (eg, sulfolane).

In the present invention, particularly preferred water-soluble organic solvents are polyhydric alcohols, alkyl ethers of polyhydric alcohols, and heterocycles, from which 2-3
It is preferable to select a kind.

The SP value according to the present invention is 18.414-3.
As the water-soluble organic solvent in the range of 0.69, ethylene glycol, diethylene glycol, triethylene glycol, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, triethanolamine, 2-pyrrolidone, etc. are preferably used,
Particularly preferably used is diethylene glycol monobutyl ether (SP value 19.437, boiling point 230
℃).

The water-soluble organic solvent according to the present invention has a boiling point of 1
A material having a temperature of 20 ° C or higher is selected. The upper limit of the boiling point is not particularly limited, but one having a melting point of 30 ° C. or lower is preferable.

Next, the organic particles will be described. The organic particles according to the present invention have SP values of 18.414 to 30.69.
(MPa) ^1/2 and water-insoluble organic particles (hereinafter, also referred to as organic particles according to the present invention) soluble or swollen by the water-soluble organic solvent having a boiling point of 120 ° C. or higher and having a molecular weight of 5000 or more. Polymers are preferable, and as the material thereof, for example, polyvinyl chloride, polyvinylidene chloride, polyacrylate, polymethacrylate, elastomer,
Ethylene-vinyl acetate copolymer, styrene- (meth) acrylic copolymer, polyester, polyvinyl ether,
It is selected from conventionally known materials such as polyvinyl acetal, polyamide, polyurethane, polyolefin, SBR, NBR, polytetrafluoroethylene, chloroprene, protein, polysaccharide, rosin ester and shellac resin. Particularly preferred organic particle materials are polyvinyl acetal resins, polyurethane resins, rosin ester resins, (meth) acrylate resins, SBR, etc., and resins composed of two or more monomers by modification or copolymerization are also available. It is preferably used and may be one in which a specific modifying group is added to a resin or one in which a leaving group is removed, two or more kinds of materials may be mixed to form an organic particle, and two or more kinds may be further used. The organic particles may be mixed and used.

In the present invention, "dissolution" means that the organic particles and the water-soluble organic solvent in the ink form a single phase in an equilibrium state, and "swelling" means that the organic particles have the same water-soluble organic solvent. To absorb and increase the volume. The preferred volume increase rate when swollen is 2 to 8 times.

The organic particles according to the present invention must be insoluble in water because they will not dissolve in ink jet recording. However, it is allowed to absorb water within a range that does not interfere with the ink absorption rate. 20% by mass relative to the mass of organic particles
May absorb water up to. Further, the organic particles according to the present invention are sufficient if they are contained in an amount such that the organic particle-containing layer is softened after printing with a pigment ink, but it is preferably 50% by mass or more with respect to the solid content in the layer. , And more preferably 75% or more.

A crosslinking agent may be used in the organic particles according to the present invention within a range that does not hinder dissolution or swelling in a water-soluble organic solvent. In the present invention, a conventionally known crosslinking agent can be appropriately selected and used as the crosslinking agent regardless of whether it is an organic substance or an inorganic substance.

The particle size of the organic particles according to the present invention greatly affects the surface gloss of the recording paper. The preferred number average particle size is 1
nm to 2 μm, and more preferably 5 nm to 1 μm. Further, when the particle size of the organic particles is 5 to 100 nm, it is possible to greatly contribute to the effect of the present invention that the difference in glossiness between the printed portion and the non-printed portion is reduced. As a method for measuring the number average particle diameter, for example, the cross section or the surface of the organic particle-containing layer is observed with an electron microscope, the particle diameters of a large number of arbitrary organic particles are calculated, and the simple average value (number average) is calculated. There is a way. It should be noted that each particle size is represented by a diameter assuming a circle having the same projected area. Alternatively, as another method, the organic particles may be dispersed in an appropriate dispersion medium and the particle size may be determined by laser diffraction / scattering particle size distribution measurement. The shape of the organic particles according to the present invention need not be spherical, and may be needle-like or plate-like. The particle size is
Calculated from the volume in terms of spheres.

In the invention according to claim 1, an embodiment consisting of the following [1-1] is preferable. [1-1]: An inkjet recording paper having a first porous layer having a porous structure as an outermost layer, having an SP value of 1
8414 to 30.69 (MPa) ^1/2 and 10 to 4 alcohol-based water-soluble organic solvent having a boiling point of 120 ° C. or higher.
An aqueous solution containing 0% by mass of 20 ml / m ^{2 is} applied to the surface of the inkjet recording paper, and the inkjet recording paper satisfies the following formula [1] when dried at room temperature to a constant state. An inkjet recording paper for pigment ink.

Formula [1] Va / V ≦ 0.4 In the formula [1], Va is the amount of water transferred at a contact time of 0.8 seconds when Bristow measurement was performed on the portion to which the aqueous solution was applied and dried. , V is the amount of water transferred at a contact time of 0.8 seconds when Bristow measurement was performed on the portion to which the aqueous solution was not applied.

The embodiment described in [1-1] above is an ink jet recording paper having good ink absorbability, and the ink absorbency is lowered after application of the solvent used as a solvent for a general pigment ink. To do. The present inventors presume that this is because the organic particles described in claim 1 form a film by the solvent, which makes it difficult for ink to pass through.

The Bristow measurement is based on the test method described in Liquid Absorption Test (see J. TAPPI Paper Pulp Test Method No. 51). The liquid used for the measurement is water, but for the purpose of facilitating the measurement, a very small amount of a dye or the like may be dissolved in water to be colored. For example, water containing 0.1% or less of the dye is also water. Shall be regarded as

Further, the above-mentioned [1-1] is more preferably the following [1-2].

[1-2]: The ink jet recording paper for pigment ink according to [1-1], which satisfies the following formula [2]:

Formula [2] Va / V ≦ 0.3 and V60 / V ≧ 0.7 In the formula [2], Va and V are Va in the formula [1],
It is synonymous with V, and V60 represents the transfer amount of water at a contact time of 0.8 seconds after the inkjet recording paper was stored at a temperature of 60 ° C. for 24 hours.

The embodiment described in [1-2] has the above-mentioned [1-
In the same manner as in the aspect 1), the ink absorption property is lowered after the solvent is applied, but the ink absorption performance is not deteriorated even after storage at 60 ° C., that is, the inkjet recording paper for pigment ink has good storage stability. Means that.

In particular, as a concrete means for obtaining the ink jet recording paper for pigment ink according to the aspect [1-2], for example, a coating liquid containing an organic particle emulsion satisfying the condition of the following formula [3] is used. A method of coating and drying on a support is preferable.

Formula [3] T0 ≧ 60, and T20 ≦ 10 In Formula [3], T0 is the minimum film-forming temperature (unit: ° C.) of the emulsion of organic particles, and T20 is diethylene glycol monobutyl ether. Against 20
The minimum film-forming temperature (unit: ° C) of the organic fine particle emulsion when added by mass% is shown.

By using the organic particle emulsion satisfying the condition of the above formula [3], the ink absorption performance is not easily deteriorated even when stored in a relatively high temperature atmosphere, so that the storage stability is good and the pigment is It is possible to produce an inkjet recording paper for pigment ink that is easily dissolved or swelled by the water-soluble organic solvent in the ink.

The minimum film forming temperature of the organic particle emulsion will be described. Here, the minimum film-forming temperature of the organic particle emulsion can be measured by the method described in ISO2115.

In the preparation of the organic particle emulsion, when diethylene glycol monobutyl ether is added to the emulsion, direct addition may cause local aggregation. For the purpose of avoiding this, diethylene glycol monobutyl ether is preferably diluted with water and added. In this case, the amount of water does not have a great influence on the measurement of the minimum film-forming temperature even if it is used up to the same volume as the emulsion.

In the present invention, the material of the organic particle emulsion satisfying the above formula [3] is not particularly limited, and specific examples substantially the same as those exemplified in the invention according to claim 1 can be mentioned.

In the organic particle emulsion, a dispersant and a surfactant are preferably used for dispersion stability,
It may be a self-emulsion type emulsion in which a hydrophilic group is added to the molecular chain.

As means for controlling the minimum film-forming temperature of the organic particle emulsion and the minimum film-forming temperature when diethylene glycol monobutyl ether is added,
Material of organic fine particles, monomer composition, molecular weight, dispersant amount,
Examples include control of particle size and the like.

Further, in the above [1-1] and [1-2] modes, more preferably, the following [1-3] mode is used.

[1-3]: The main component of the first porous layer is
SP value is 18.414-30.69 (MPa) ^1/2 ,
And water-insoluble organic particles having a boiling point of 120 ° C. or higher that dissolves or swells in an alcohol-based water-soluble organic solvent, and further comprises a second porous layer containing inorganic particles and a water-soluble binder as a main component. The inkjet recording paper according to [1-1] or [1-2], which is provided on the functional layer.

The embodiment described in the above [1-3] is the first aspect.
In the invention according to, a high-ink-absorbent inkjet recording paper, characterized in that it has a void layer under a layer containing water-insoluble organic particles that is dissolved or swelled by a water-soluble organic solvent, After the pigment ink is applied, the ink absorbency is lowered due to the fusion of the organic particles.

In the emulsion containing organic particles, a dispersant or a surfactant is preferably used for stabilizing the dispersion, but a self-emulsion type emulsion having a hydrophilic group in the molecular chain may be used.

The organic particles described in the aspects [1-1], [1-2] and [1-3] are controlled by the material of the organic particles, monomer composition, molecular weight, dispersant amount, particle size and the like. It can be prepared by carrying out.

Further, another preferred embodiment of the invention according to claim 1 is the embodiment consisting of the following [1-4].

[1-4]: Containing 5% by mass or more of a repeating unit represented by the following general formula (1) as a copolymerization component,
An ink absorption layer having a porous layer containing a polymer having a glass transition temperature (Tg) of 70 ° C. or higher and organic particles having an average particle size of 100 nm or less as a surface layer is provided on a support. Is an inkjet recording paper for pigment ink.

[0061]

[Chemical 1]

In the general formula (1), X represents --O-- or --N (R ₂ )-, R ₁ is a hydrogen atom or a methyl group, and R ₂ is a hydrogen atom or a C 1-8 carbon atom. When an alkyl group is represented and X is —O—, J is an alkylene group having 2 to 8 carbon atoms and optionally having an ether structure or a thioether structure, and Y is a hydroxyl group, an alkoxyl group or carbamoyl. Represents a group. X is -N (R
₂ )-, J is a single bond or an alkylene group having a carbon number of 2 to 8 and optionally having an ether structure or a thioether structure, and Y is a hydrogen atom, a hydroxyl group, an amino group or an alkoxyl group. Alternatively, it represents a carbamoyl group.

In the embodiment consisting of the above [1-4],
Organic particles are 50% by mass or more based on the solid content of the porous layer 9
It is preferably 0% by mass or less, the porous layer contains inorganic particles, and the inorganic particles are 10% by mass or more and 50% by mass or less of the organic particles.

Next, the details of the organic particles according to [1-4] will be described below. The repeating unit represented by the general formula (1) will be described.

From the viewpoint of preferably exhibiting the desired effects of the present invention, it is preferable that the repeating unit represented by the general formula (1) has hydrophilicity as the organic particles. It can be obtained by polymerizing a hydrophilic monomer such as a monomer, an acrylamide monomer and / or a methacrylamide monomer, but the present invention is not limited thereto.

[0066]

[Chemical 2]

[0067]

[Chemical 3]

[0068]

[Chemical 4]

Hydrophilicity is imparted to the repeating unit represented by the general formula (1) to form the general formula (1).
Although each has a partial structure such as X, J, and the substituent Y, it is preferred in the present invention that the substituent Y imparts hydrophilicity.

The substituent used for imparting hydrophilicity to the repeating unit represented by the general formula (1) includes
"Structure-activity relationship of drugs (guideline for drug design and mechanism of action)" (Chemical domain special issue No. 122) Structure-activity relationship round-table conference, Nankodo (1980), hydrophobic parameters as described in p96-103. A substituent having a negative (π) can be used.

The organic particles according to the present invention are required to have the specific repeating unit represented by the above general formula (1) as a copolymerization component in an amount of 5% by mass or more, but 10% by mass or more is contained. It is preferable.

Further, the organic particles themselves are preferably hydrophilic but not water-soluble, so that the content is preferably adjusted to a range of 10% by mass to less than 50% by mass.

Specific examples of the polymer containing 5% by mass or more of the repeating unit represented by the above general formula (1) as a copolymerization component, which is used as a constituent component of the fine particles according to the present invention, are shown below. The invention is not limited to these.

[0074]

[Chemical 5]

[0075]

[Chemical 6]

On the other hand, as the other monomer component of the polymer constituting the organic particles, any conventionally known one having an ethylenically unsaturated group is selected. These may be a single type or a plurality of types. Examples of such a monomer include alkyl ester or alkyl amide of acrylic acid or methacrylic acid, and methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, i. -Butyl acrylate, i-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate,
Styrene, vinyltoluene, α-methylstyrene, vinyl acetate, acrylonitrile, methacrylonitrile, or acrylic acid, methacrylic acid, fumaric acid, itaconic acid, maleic acid, or dimethylaminomethyl acrylate, diethylaminomethyl acrylate, dibutylaminomethyl Acrylate, dihexylaminomethyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, (t-butyl) aminoethyl acrylate, diisohexylaminoethyl acrylate, dihexylaminopropyl acrylate, di (t-butyl) aminohexyl acrylate and the like. . Of these, styrene, methyl methacrylate and n-butyl acrylate are preferably used.

The organic particles according to the present invention are preferably prepared as an aqueous emulsion to form a coating solution, and in that case, the ionicity of the emulsion particles is preferably equal to or nonionic with the coating solution. . The ionicity of the coating liquid for the layer containing organic particles is preferably equal to the ionicity of the coating liquid for the other layer, or nonionic. Most preferably, the organic particles and the coating liquid are all ionic or cationic. The ionicity of the organic particle emulsion can be adjusted by the ionicity of the emulsifier used or the ionicity of the copolymerization component.

Usually, the ink jet recording paper is used at room temperature, but the storage condition before use is not always room temperature, and in particular, in a sealed car in the summer, the temperature is very high. It is desired that it can be used without any trouble even after passing through such an environment. Therefore, the glass transition temperature (Tg) of the organic particles according to the aspect [1-4] is 70 ° C.
It is necessary to be the above, but it is preferably 80 ° C or higher, and more preferably 90 ° C to 120 ° C.

The glass transition temperature (Tg) of the organic particles is 70.
When the temperature is lower than 0 ° C., fusion of the organic particles due to heating is likely to occur, and as a result, the voids on the surface of the recording paper are reduced or reduced, and the ink absorption rate is likely to be reduced.

Here, the Tg of the polymer which is a constituent component of the organic particles according to the present invention is calculated by the mass fraction from the Tg of the monomer homopolymer as the copolymerization component and the monomer composition ratio. Is possible. For example, styrene (homopolymer Tg = 100 ° C. = 373K): n-butyl acrylate (homopolymer Tg = −54 ° C. = 219K).
Tg of a polymer having a composition of 4: 1 (mass ratio) is 1 / ((1 / 373K) × 4/5 + (1/219
K) × 1/5) = 327K (= 54 ° C.).
For the Tg of the monomer homopolymer, see POLYMER
HANDBOOK (A WILLEY-INTERSC
Many measurement values are published in IENCE PUBLICATION).

In the embodiment described in [1-4], from the viewpoint of obtaining a remarkable effect, the average particle size of the organic particles is 100 n.
m or less, but preferably 60 nm
Or less, more preferably 20 to 40 nm,
The organic particles according to the present invention are preferably synthesized in water by a conventionally known emulsion polymerization method or the like. The particle size can be adjusted within the range of about 20 nm to about 100 nm by a conventionally known method such as adjusting the type and amount of the emulsifier and the monomer component.

In order to exert the effect of the present invention remarkably, the content of the organic particles in the porous layer arranged on the surface of the ink absorbing layer is preferably 50 to 90% by mass. Effectively prevent the fusion of organic particles with each other,
From the viewpoint of further increasing the ink absorption rate, it is preferable to contain inorganic particles as described below.

The content of the inorganic particles in the porous layer is preferably 10% by mass or more and less than 50% by mass. The content rate here is the content rate with respect to the solid content in the porous layer, and voids are excluded from the calculation.

In the present invention, the porous layer according to the present invention is provided as at least the surface layer. However, the porous layer alone may form the ink absorbing layer, but the lower layer may have a different composition. It may have an ink absorption layer. The ink absorbing layer that may be provided in the lower layer is
As described above, the swelling layer type ink absorbing layer or the void type ink absorbing layer may be used. Further, the swelling type ink absorbing layer and the void type ink absorbing layer may be combined. Particularly preferred in the present invention is one having a void-type ink absorbing layer as a lower layer of the layer containing the organic particles according to the present invention, and by adopting this constitution, the ink absorbing speed is high, and high quality with less unevenness You can get a print of.

The organic particles according to the present invention are sufficient if they are contained in an amount such that the organic particle-containing layer is softened after printing with the pigment ink, but it is preferably 50% by mass or more based on the solid content in the layer. , And more preferably 75% or more.

Next, the invention according to claim 2 will be described. According to a second aspect of the present invention, there is provided an inkjet recording paper for pigment ink, comprising a support, a first porous layer containing at least inorganic particles and a hydrophilic binder as main components, and an SP value of 18.414 to 30. An ink absorption layer sequentially provided with a second porous layer containing organic particles insoluble in water, which is dissolved or swollen by a water-soluble organic solvent having a boiling point of 120 ° C. or higher and a pressure of 69 (MPa) ^1/2. It is characterized by having.

The layer containing the organic particles according to the present invention has a relatively low porosity, and when the ink absorbing layer is formed of a single layer, a thickness tends to be required to secure the absorption capacity. On the other hand, since the void layer having inorganic particles and the hydrophilic binder as the main components has a high void ratio, a thinner layer can absorb a large amount of ink. Therefore, it is preferable to provide an ink absorbing layer having both a layer containing organic particles and a porous layer containing inorganic particles and a hydrophilic binder as main components. The thickness of the organic particle-containing porous layer is 0.1 with respect to the thickness of the entire ink absorbing layer.
-30% is preferable, and 0.5-20% is more preferable.

In the invention according to claim 2, a particularly preferred embodiment is the porous layer according to the above-mentioned [1-4],
That is, the repeating unit represented by the general formula (1) is contained as a copolymerization component in an amount of 5% by mass or more, a polymer having a glass transition temperature (Tg) of 70 ° C. or more, and an average particle diameter of 100 nm or less. In this mode, the porous layer containing certain organic particles is used as the second porous layer. Further, claim 2
In the invention according to, the most preferred embodiment is an inkjet recording paper for pigment ink, wherein the thickness of the first porous layer is 5 to 50 μm and the thickness of the second porous layer is 0.1 to 5 μm. is there.

The ink jet recording paper of the present invention preferably has a void layer containing inorganic fine particles and a hydrophilic binder as main components as described above.

The preferable void layer will be described below. As the inorganic fine particles that can be used in the present invention,
For example, 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 Examples thereof include earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudo-boehmite, aluminum hydroxide, lithopone, zeolite, and white inorganic pigments such as magnesium hydroxide.

From the viewpoint of obtaining a high glossiness, the particle size of the above-mentioned inorganic fine particles is preferably 0.01 to 1 μm,
More preferably, it is 0.02 to 0.1 μm.

The term "inorganic fine particles" used herein means that even primary particles are 2
Secondary particles may be used. The particle size of the inorganic fine particles is the particle size of the highest order particles observed in the dry film.

In the present invention, even when a composite particle of inorganic fine particles and a small amount of organic polymer is used, it is regarded as substantially inorganic fine particles. Also in this case, the particle size of the highest order particles observed in the dry film is defined as the particle size of the inorganic fine particles. In this case, in the composite particles of the inorganic fine particles and a small amount of the organic polymer, the mass ratio of organic polymer / inorganic fine particles is about 1/100 to 1/4.

The average particle diameter of the inorganic fine particles is obtained as a simple average value (number average) by observing the cross section and the surface of the void layer with an electron microscope and determining the particle diameters of a large number of arbitrary particles. Here, each grain size is represented by a diameter assuming a circle equal to the projected area.

In the present invention, as the inorganic fine particles, from the viewpoint of low cost and high reflection density,
Fine particles having a low refractive index are preferred, and silica, and more preferably silica or colloidal silica synthesized by a vapor phase method is more preferred. Further, vapor-phase process silica treated with cation surface, colloidal silica and alumina treated with cation surface, colloidal alumina, pseudo-boehmite and the like can also be used.

The hydrophilic binder used in the ink absorbing layer is, for example, polyvinyl alcohol, gelatin, polyethylene oxide, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, carrageenan (κ, ι, λ, etc.),
Examples include agar, pullulan, water-soluble polyvinyl butyral, hydroxyethyl cellulose, carboxymethyl cellulose and the like. It is also possible to use two or more of these hydrophilic binders in combination. The hydrophilic 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 and anion-modified polyvinyl alcohol having an anionic group. The modified polyvinyl alcohol of is also included.

As the polyvinyl alcohol obtained by hydrolyzing vinyl acetate, those having an average degree of polymerization of 1000 or more are preferably used, and particularly, the average degree of polymerization is 1500 to 50.
Those of 00 are preferably used. The saponification degree is 7
0 to 100% is preferable, and 80 to 99.5% is particularly preferable.

As the cation-modified polyvinyl alcohol, for example, a primary to tertiary amino group or a quaternary ammonium group as described in JP-A-61-10483 can be used as the main chain or side chain of the polyvinyl alcohol. The polyvinyl alcohol contained therein is obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate. Further, two or more kinds of polyvinyl alcohols can be used in combination, such as different degrees of polymerization and different types of modification.

The addition amount of the inorganic fine particles used in the ink absorbing layer depends on the required ink absorbing capacity, the porosity of the void layer,
Depending on the type of inorganic fine particles and the type of hydrophilic binder, it is generally 5 to 30 g per 1 m ² of recording paper,
It is preferably 10 to 25 g.

The ratio of the inorganic fine particles used in the ink absorbing layer to the hydrophilic binder is approximately 2: 1 by mass.
It is preferably 20: 1, and particularly preferably 3: 1 to 10: 1.

The phrase "composed mainly of inorganic particles and a hydrophilic binder" in the invention according to claim 2 means that the total mass of the inorganic particles and the hydrophilic binder is based on the total solid content in the porous layer. It means 50% or more, and preferably,
It is 75% or more.

In the ink jet recording paper of the present invention, a cationic polymer is preferably used for the purpose of stabilizing the image by storing after recording.

Examples of the cationic polymer that can be used in the present invention include polyethyleneimine, polyallylamine, polyvinylamine, dicyandiamide polyalkylene polyamine condensate, polyalkylene polyamine dicyandiamide ammonium salt condensate, dicyandiamide formalin condensate, epichlorohydrin. Dialkylamine addition polymer, diallyldimethylammonium chloride polymer, diallyldimethylammonium chloride / SO ₂ copolymer, polyvinylimidazole, vinylpyrrolidone / vinylimidazole copolymer, polyvinylpyridine, polyamidine, chitosan, cationic starch, vinylbenzyltrimethyl Ammonium chloride polymer, (2-methacryloyloxyethyl) trimethylammonium chloride Id polymer, dimethylaminoethyl methacrylate polymer, and the like. Further, examples include the cationic polymer described on both days of Chemical Industry Bulletin August 15 and 25, 1998, and the polymer dye fixing agent described in “Introduction to Polymeric Drugs” issued by Sanyo Chemical Industry Co., Ltd.

In the ink jet recording paper of the present invention, it is preferable to use a hardener for the purpose of adjusting the physical strength of the ink absorbing layer or preventing cracks in the coating film during coating and drying.

The hardener is generally a compound having a group capable of reacting with the hydrophilic binder, or a compound accelerating the reaction between different groups of the hydrophilic binder. It can be appropriately selected according to the type.

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.

Particularly preferably, when polyvinyl alcohol and / or cation-modified polyvinyl alcohol is used as the hydrophilic binder, a hardener selected from boric acid and salts thereof and an epoxy hardener is preferably used. Most preferred are hardeners selected from boric acid and its salts.

The boric acid or a salt thereof means an oxygen acid having a boron atom as a central atom and a salt thereof, and specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, octaboric acid, and them. Includes salt.

The amount of the above-mentioned hardener used varies depending on the kind of the hydrophilic binder, the kind of the hardener, the kind of the inorganic fine particles and the ratio to the hydrophilic binder, but usually 5 to 500 mg per 1 g of the hydrophilic binder, Preferably 10
It is 300 mg.

Various additives other than those described above can be used in the ink absorbing layer of the ink jet recording sheet of the present invention and other layers provided as necessary. For example, polystyrene, polyacrylic acid esters, polymethacrylic acid esters, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or copolymers thereof, urea resin, or organic latex fine particles such as melamine resin. , Various cationic or nonionic surfactants, UV absorbers described in JP-A-57-74193, 57-87988 and 62-261476, JP-A-57-74192 and 57-
87989, 60-72785, 61-146.
591, JP-A-1-95091 and 3-1337.
An anti-fading agent described in JP-A No. 6-62, JP-A-59-42.
993, 59-52689, 62-28006.
9, No. 61-242871, and Japanese Patent Laid-Open No. 4-2192.
66, etc., optical brighteners, sulfuric acid, phosphoric acid,
Various known additives such as pH adjusting agents such as citric acid, sodium hydroxide, potassium hydroxide and potassium carbonate, defoaming agents, preservatives, thickeners, antistatic agents, matting agents and the like may be contained.

The ink absorbing layer may be composed of two or more layers. In this case, the structures of these ink absorbing layers may be the same or different from each other.

As the support that can be used in the present invention, any support conventionally known for ink jet recording paper can be appropriately used, and it may be a water-absorbing support, but is preferably a non-water-absorbing support. . That is, in the case of the non-water-absorbent support, the water-soluble organic solvent in the pigment ink remains in the recording paper in a larger amount than in the case of the water-absorbent support, which effectively acts on the dissolution of organic particles and the like. Therefore, it is estimated that the effects of the present invention can be remarkably exhibited. To be precise, it is preferable to use a "support that does not absorb the water-soluble organic solvent in the pigment ink", but here, even if a non-water-absorbing support is used, the effect of the present invention is remarkably achieved. I think I can play.

Examples of the water-absorbent support that can be used in the present invention include sheets and plates having general paper, cloth, wood and the like. In particular, paper is the water-absorbent material of the substrate itself. It is most preferable because it is excellent in terms of cost and cost. As the paper support, chemical pulp such as LBKP and NBKP, GP, CGP, RMP, TMP, CTMP, C
It is possible to use mechanical pulps such as MP and PGW and wood pulp such as waste paper pulp such as DIP as main raw materials.
In addition, various fibrous substances such as synthetic pulp, synthetic fibers, and inorganic fibers can be appropriately used as raw materials, if necessary.

If necessary, various conventionally known additives such as a sizing agent, a pigment, a paper strengthening agent, a fixing agent, a fluorescent brightening agent, a wet paper strengthening agent and a cationizing agent may be added to the above paper support. Can be added.

The paper support can be produced by mixing the above fibrous substances such as wood pulp with various additives and using various paper machines such as a Fourdrinier paper machine, a cylinder paper machine, and a twin wire paper machine. . Further, if necessary, it may be subjected to size press treatment with starch, polyvinyl alcohol or the like in a papermaking stage or a papermaking machine, various coat treatments, and calendar treatment.

Non-water-absorptive supports that can be preferably used in the present invention include transparent supports and opaque supports.
As the transparent support, for example, polyester resin, diacetate resin, triate sate resin, acrylic resin, polycarbonate resin, polyvinyl chloride resin, polyimide resin, cellophane, a film having a material such as celluloid. Among them, those having a property of withstanding radiant heat when used for an overhead projector (OHP) are preferable, and polyethylene terephthalate is particularly preferable. The thickness of such a transparent support is preferably 50 to 200 μm.

Examples of the opaque support include resin-coated paper (so-called RC paper) having a polyolefin resin coating layer in which a white pigment or the like is added to at least one of base papers, polyethylene terephthalate and white pigments such as barium sulfate. So-called white pet obtained by adding the above is preferable.

For the purpose of increasing the adhesive strength between the various supports and the ink absorbing layer, it is preferable to subject the support to corona discharge treatment or subbing treatment prior to coating the ink absorbing layer. Furthermore, the ink jet recording paper of the present invention does not necessarily have to be colorless and may be a colored recording sheet.

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

The paper support laminated with such polyethylene will be described below. The base paper used for the paper support is made from wood pulp as a main raw material, 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, NB
KP, NBSP, LDP, NDP, LUKP, NUKP
Any of the above can be used, but LBK with a large amount of short fibers
It is preferable to use more P, NBSP, LBSP, NDP, and LDP. However, the ratio of LBSP or LDP is preferably 10 to 70% by mass.

As the above pulp, a chemical pulp containing few impurities (sulfate pulp or sulfite pulp) is preferably used, and a pulp having a whiteness 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 the above, 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. Is preferred. In addition, mass% of 4 mesh residue
Is preferably 20% by mass or less.

The basis weight of the base paper is preferably 30 to 250 g,
Particularly, 50 to 200 g is preferable. The thickness of the base paper is 40-2
50 μm is preferable.

The base paper may be given a high smoothness by calendering at the papermaking stage or after papermaking. Base paper density is 0.
7 to 1.2 g / m ² (JIS-P-8118) is common. Furthermore, the stiffness of the base paper is preferably 20 to 200 g under the conditions specified in JIS-P-8143. A surface sizing agent may be applied to the surface of the raw paper.

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 for coating the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or
Or high density polyethylene (HDPE) but other L
LDPE, polypropylene, etc. can be partially used.

In particular, for the polyethylene layer on the ink absorbing layer side, rutile or anatase type titanium oxide is added to polyethylene, as is widely used in photographic printing paper,
Those with improved opacity and whiteness are preferred. The content of titanium oxide is usually 3 to 20% by mass, preferably 4 to 13% by mass, based on polyethylene.

The polyethylene-coated paper may be used as a glossy paper, or may be subjected to a so-called patterning process when polyethylene is melt-extruded on the surface of the base paper for coating, and the matte surface and the silk-like surface are obtained. A surface-formed product can also be used in the present invention. In the polyethylene-coated paper, it is particularly preferable to keep the water content in the paper at 3 to 10% by mass.

The method of applying various ink absorbing layers, such as a void layer and an undercoat layer of the recording paper of the present invention, which are appropriately provided as necessary, to the support can be appropriately selected from known methods. . A preferred method is obtained by applying a coating solution forming each layer on a support and drying. In this case, two or more layers can be coated at the same time, and a simultaneous multi-layer coating method in which all hydrophilic binder layers can be coated once is preferable.

As the coating method, for example, roll coating method, rod bar coating method, air knife coating method, spray coating method, curtain coating method, or extrusion coating using a hopper described in US Pat. No. 2,681,294. The method is preferably used.

Next, the pigment ink recorded on the recording paper of the present invention will be described. The pigment ink may be a water-based pigment ink or an oil-based pigment ink, but the water-based pigment ink is preferable.

As the pigment, pigments conventionally known for ink jet can be used. For example, azo chelate, water-insoluble azo pigment, condensed azo pigment, azo pigment such as chelate azo pigment, phthalocyanine pigment, perylene and perylene pigment, anthraquinone. Pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindoninone pigments, polycyclic pigments such as quinophthaloni pigments, basic dye type lakes, acid dye type lakes and other dye lakes, nitro pigments, nitroso Pigment, aniline black,
Examples thereof include organic pigments such as daylight fluorescent pigments and inorganic pigments such as carbon black.

Examples of pigment dispersants include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, naphthalene sulfonates, alkyl phosphates, and polyoxyalkylene alkyls. Examples thereof include ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, and polymer surfactant.

In addition to the above, the pigment ink may contain various additives as required. For example, a water-soluble organic solvent (eg, propanol, hexanol, ethylene glycol, diethylene glycol, glycerin, hexanediol, urea, etc.) , Surfactants (for example, anionic surfactants and nonionic surfactants, fluorochemical surfactants, etc.), water-soluble polymers, polymer dispersions, preservatives, antifungal agents, viscosity modifiers, pH adjusters Etc. can be mentioned.

The dispersion of the pigment may be carried out by using various dispersing devices such as a ball mill, a sand mill, a roll mill, a colloid mill, an ultrasonic homogenizer, a wet jet mill, a high pressure homogenizer, or a combination of two or more kinds as necessary. it can. A method of removing coarse particles from the pigment dispersion using a centrifugal separator or various filters is also preferable.

As the ink jet recording ejection method in the present invention, an electro-mechanical conversion method (for example, single cavity type, double cavity type, bender type,
Piston type, shear mode type, shared wall type, etc., electric-heat conversion type (for example, thermal inkjet type, bubble jet (R) type, etc.), electrostatic attraction type (for example, electric field control type, slit jet type, etc.) Further, a discharge method (for example, a spark jet type) or the like can be given as a specific example.

The preferable maximum ink discharge amount in the present invention is 10 to 35 ml / m ² . The average particle size of the pigment particles is 300 nm or less, preferably 200 nm or less,
Particularly preferred is 150 to 50 nm. By adjusting the average particle size to the above range, the difference in glossiness between the printed portion and the non-printed portion is remarkably reduced, and the scratch resistance is remarkably improved. The present inventor estimates that this is because most of the ink pigment particles are embedded in the surface layer.

[0139]

EXAMPLES Examples of the present invention will be described below.
The invention is not limited to these examples. In addition,
"%" In the examples indicates mass% unless otherwise specified.

Example 1 <Preparation of Silica-Cationic Polymer Dispersion 1> 100 g of a 15% aqueous solution of the cationic polymer (P1) was added to fine particle silica having an average primary particle diameter of 12 nm (manufactured by Tokuyama Corp.,
500 g of a 20% aqueous dispersion of QS-20), 3.0 g of boric acid and 0.7 g of borax were added and dispersed by a high-speed homogenizer to obtain a pale-white silica-cationic polymer dispersion 1.

[0141]

[Chemical 7]

<< Preparation of Coating Solution 1 >> 610 g of the above silica-cationic polymer dispersion 1 was heated to 45 ° C., 5 ml of a 10% aqueous solution of polyvinyl alcohol (Kuraray, PVA203) and another polyvinyl alcohol (Kuraray,
290 ml of 6% aqueous solution of PVA 245)
It was added after the temperature was raised to ℃. Finally, the total volume of the liquid is 1
Pure water at 45 ° C. was added to 000 ml to obtain a semi-transparent coating liquid 1.

<< Preparation of Inkjet Recording Papers 1-10 >> [Preparation of Inkjet Recording Papers 1] Liquid temperature 4 on a paper support (thickness 230 μm) coated on both sides with polyethylene.
After coating the coating liquid 1 at 5 ° C with a wire bar and drying,
Ink jet recording paper 1 was obtained by storing it in a thermostat at 40 ° C. and 80% RH for 12 hours. Dry film thickness is 35
was μm. The inkjet recording paper will be simply referred to as recording paper hereinafter.

[Preparation of Recording Paper 2] On the coated surface of recording paper 1, the following organic particle dispersion liquid 1 was further applied with a wire bar and dried with warm air at 60 ° C. Obtained. The thickness of the layer containing organic particles was 2 μm.

(Preparation of Organic Particle Dispersion Liquid 1) A shown below
Both the liquid and the liquid B were heated to a liquid temperature of 70 ° C., mixed and immediately emulsified and dispersed by a tabletop homogenizer, and methylene chloride was volatilized under reduced pressure. The solid concentration of the obtained organic particle dispersion liquid 1 was 10%, and the number average particle diameter measured by laser diffraction / scattering particle size distribution measurement was 1.2 μm.

<Liquid A> Polyvinyl butyral (manufactured by Sekisui Chemical Co., BL-S) 10 parts Methylene chloride 50 parts <Liquid B> Surfactant (manufactured by Kao, Emulgen 220) 0.2 parts Water 100 parts [of recording paper 3 Preparation] On the recording paper 1, the organic particle dispersion liquid 1 was dried to a thickness of 8 μm using a wire bar.
The recording paper 3 was manufactured by applying and drying so that the thickness became m.

[Preparation of Recording Paper 4] Recording Paper 4 was prepared by coating and drying the organic particle dispersion liquid 1 on the recording paper 1 with a wire bar so that the dry film thickness was 12 μm. .

[Preparation of Recording Paper 5] 40 of Coating Solution 1
Parts and 60 parts of the organic particle dispersion liquid 1 were mixed to prepare a coating liquid 2. The coating liquid 2 was applied onto the recording paper 1 with a wire bar and dried to prepare a recording paper 5.
The thickness of the layer containing organic particles was 8 μm.

[Preparation of Recording Paper 6] 70 of Coating Solution 1
And 30 parts of the organic particle dispersion liquid 1 were mixed to prepare a coating liquid 3. The coating liquid 3 was applied onto the recording paper 1 with a wire bar and dried to prepare a recording paper 6.
The thickness of the layer containing organic particles was 8 μm.

[Preparation of Recording Paper 7] On a recording paper 1, a polyvinyl butyral emulsion (made by Chukyo Yushi Co., Ltd., Resem VB J-667, average particle size of 0.
5 μm) was applied and dried to prepare a recording paper 7. Thickness of polyvinyl butyral emulsion containing layer is 2μm
Met.

[Preparation of Recording Paper 8] A urethane emulsion (Daiichi Kogyo Seiyaku Co., Ltd., Superflex E-2500, average particle size 0.96 μm) was applied onto the recording paper 1 using a wire bar and dried. A recording sheet 8 was prepared. The thickness of the urethane emulsion-containing layer was 2 μm.

[Preparation of Recording Paper 9] A styrene- (meth) acrylic emulsion (manufactured by Asahi Chemical Industry Co., Ltd., Polytron E390M, average particle size 0.15 μm) was applied onto the recording paper 1 and dried. The recording paper 9 was prepared. The styrene- (meth) acrylic emulsion-containing layer had a thickness of 2 μm.

[Preparation of Recording Paper 10] On the recording paper 1,
Styrene-butadiene latex emulsion (manufactured by Nippon Zeon, Nipol LX43
3C, average particle size 0.1 μm) was applied and dried to prepare a recording paper 10. The thickness of the styrene-butadiene latex emulsion-containing layer was 2 μm.

<< Solubility Test of Each Organic Particle >> Each of the organic particles and each emulsion used in the preparation of the above recording papers 2 to 10 were mixed with diethylene glycol monobutyl ether [SP].
A value of 19.437 (MPa) ^1/2 , a boiling point of 230 ° C.] and mixing at room temperature resulted in complete dissolution. On the other hand, glycerin [S
When a similar test was performed using a P value of 33.8 (MPa) ^1/2 and a boiling point of 290 ° C.], neither organic particles nor emulsion was dissolved or swollen.

<< Electron Microscopic Observation of Surface and Cross Section of Recording Paper >> (Observation of Surface and Cross Section of Untreated Recording Material) As a result of observing the surface and cross section of the recording papers 1 to 10 prepared above with an electron microscope, It was also possible to confirm the formation of the void layer due to the particles and the gaps on the surface and the cross section of the recording paper.

(Observation of surface and cross section of recording material after treatment A) Observation of the surface and cross section of the recording papers 1 to 10 subjected to the following treatment A with an electron microscope revealed that the recording papers 2 to 10 were: It was observed that the organic particles were melted or swollen and thus fused with each other.

[0157] <Process A> diethylene glycol monobutyl ether [SP value 19.437 (MPa) ^1/2, boiling point 230 ° C.] 20% aqueous solution of was uniformly sprayed on the surface of the recording sheet 10. The coating amount was 20 ml / m ² . Next, this portion was dried in an environment of 23 ° C. and 55% RH for 1 hour.

(Observation of Surface and Cross Section of Recording Material after Treatment B) Observation of the surface and cross section of the recording papers 1 to 10 subjected to the following treatment B with an electron microscope showed that before treatment B was applied. There was almost no change from the state of No. 2 and no fusion of organic particles was observed on any of the recording papers 2 to 10.

<Treatment B> Glycerin [SP value 33.8]
(MPa)^1/2, Boiling point 290 ° C.]
The surfaces of recording papers 1 to 10 were uniformly spray-coated. Application
Volume is 20 ml / m ²Met. Then, this part 23
It was dried in an environment of ℃ and 55% RH for 1 hour.

[0160]   << Preparation of ink liquid >>   (Yellow ink)   C. I. Pigment Yellow 74 (Pigment average particle size 0.14 μm)                                                           30.0 g   Demor C (manufactured by Kao Corporation) 18.5g   180g ethylene glycol   Triethylene glycol monobutyl ether 120g   Olfin (Nissin Chemical Co., Ltd.) 4g   Proxel (manufactured by Zeneca Corporation) 2g   Sodium chloride 0.25g The total amount was adjusted to 1000 g with ion-exchanged water.

[0161]   (Magenta ink)   C. I. Pigment Red 12 (Pigment average particle size 0.090 μm)                                                           35.2g   Demor C (manufactured by Kao Corporation) 21.5g   Ethylene glycol 1780g   Triethylene glycol monobutyl ether 140g   Olfin (Nissin Chemical Co., Ltd.) 4g   Proxel (manufactured by Zeneca Corporation) 2g   Sodium chloride 0.25g The total amount was adjusted to 1000 g with ion-exchanged water.

[0162]   (Cyan ink)   C. I. Pigment Blue 15 (Pigment average particle size 0.10 μm)                                                           31.0 g   Demor C (manufactured by Kao Corporation) 21.5g   180g ethylene glycol   Triethylene glycol monobutyl ether 120g   Olfin (Nissin Chemical Co., Ltd.) 4g   Proxel (manufactured by Zeneca Corporation) 2g   Sodium chloride 0.25g The total amount was adjusted to 1000 g with ion-exchanged water.

[0163]   (Black ink)   Carbon black (average particle size 0.18 μm) 22.5 g   Demor C (manufactured by Kao Corporation) 15.5g   220g ethylene glycol   Triethylene glycol monobutyl ether 120g   Olfin (Nissin Chemical Co., Ltd.) 4g   Proxel (manufactured by Zeneca Corporation) 2g   Sodium chloride 0.25g The total amount was adjusted to 1000 g with ion-exchanged water.

Each of the above inks was used after being dispersed by a sand mill disperser and then filtered twice with a filter having a pore size of 1 μm.

<Image Output> Using each color ink prepared above, an on-demand type ink jet printer equipped with a piezo type head having a nozzle diameter of 25 μm, a driving frequency of 12 kHz, a number of nozzles of each color of 128, and a nozzle density of 180 dpi between the same colors is used. And recording density 360 x 360 dp
Under the condition of i, solid images were printed on the prepared recording papers 1 to 10 while changing the ink ejection amounts of the respective images of Y, M, C, B, G, R and K. The term "dpi" in the present invention means the number of dots per 2.54 cm.

<< Characteristic Evaluation of Output Image >> The following characteristic evaluation was performed on each output image created as described above.

(Evaluation of Difference in Glossiness) Regarding the recording papers 1 to 10 on which the above image was output, the difference in glossiness between the printed portion and the non-printed portion was visually observed by 10 general monitors,
The difference in glossiness was judged according to the criteria described below, and the evaluation rank that was the largest among the 10 people was the glossiness difference rank of the recording paper.

⊚: Almost no difference in glossiness, little difference between printed and non-printed areas ○: Difference in glossiness is recognized, but the image is observable Δ: Glossiness in printed area is extremely low , The difference in glossiness from the non-printed area is large and the image feels strange (evaluation of scratch resistance) The density of the printed area when the highest density area of each output image is rubbed 10 times with an eraser (MONO Tombow Pencil Co., Ltd.) The degree of occurrence of deterioration was visually observed, and the scratch resistance was evaluated according to the following criteria.

⊚: No decrease in density was observed in the printed area. ◯: A slight decrease in density was observed in the printed area. Δ: A slight decrease in density was observed in the printed area, but it was in the practically allowable range. Evaluation of Beading) The solid image printed portion of each recording paper was visually observed and beading was evaluated according to the following criteria.

◯: No unevenness of printed image is observed even at an observation distance of 30 cm. Δ: Unevenness of printed image is observed at an observation distance of 30 cm, but almost no unevenness of printed image is observed at an observation distance of 60 cm. Table 1 shows the respective evaluation results obtained by.

[0171]

[Table 1]

As is clear from Table 1, the recording sheets 2 to 10 of the present invention have a small difference in glossiness between the printed portion and the non-printed portion, and are excellent in scratch resistance and beading characteristics, as compared with the comparative examples. I know that

Example 2 << Preparation of Inkjet Recording Paper >> (Preparation of Inkjet Recording Paper 1A) In the preparation of recording paper 1 described in Example 1, except that Aerosil 300 (manufactured by Aerosil Co., Ltd.) was further added as fine particle silica. Similarly, a recording sheet 1A was produced.

(Preparation of Inkjet Recording Papers 21-23) After coating each of the organic particle emulsions (L2-1 to L2-3) shown in Table 2 on the recording paper 1A prepared above using a wire bar, The recording papers 21 to 23 were manufactured by drying at 40 ° C. In addition, each coating amount was appropriately adjusted so that the thickness of each organic emulsion-containing layer was 2 μm.

(Preparation of Inkjet Recording Papers 24-27) The organic particle emulsion (L2-3) was mixed with the silica-cationic polymer dispersion 1 prepared in Example 1,
The solid content ratio of organic particles to the total solid content in the mixed solution is shown in Table 2.
The amount added was adjusted appropriately so as to obtain the amount described in. Each of the mixed liquids was applied onto the recording paper 1 prepared in Example 1 using a wire bar and dried at 40 ° C. to prepare inkjet recording papers 24 to 27. Each coating amount was appropriately adjusted so that the thickness of each organic particle emulsion-containing layer was 2 μm.

<< Electron Microscopic Observation of Surface and Cross Section of Recording Paper >> When the surfaces of the above-prepared recording papers 21 to 27 were observed with an electron microscope, voids were observed in all of them. Furthermore, after the processing A described in Example 1 was applied to each recording sheet, the surface was observed with an electron microscope, and in each case, a state in which organic particles were fused to each other was observed.

<Image output> According to the method described in Example 1, the recording papers 21 to 27 produced above were used to output an image.

<< Evaluation of Characteristics of Output Image >> For each output image prepared as described above, in addition to the evaluation of gloss difference, scratch resistance and beading, in the same manner as in Example 1. According to the method described below, the Bristow measurement and the beading after the forced deterioration treatment were evaluated.

(Bristow Measurement of Recording Medium: Measurement of Ink Dislocation Amount) Bristow measurement is described in J. TAPPI paper pulp test method No. 51-87 Measured according to the liquid absorption test method for paper or paperboard (Bristow method), contact time 0.8
The transfer amount of water (ml / m ² ) was determined in seconds.

Specifically, the recording medium is set at 25 ° C. and 50% R
After standing for 12 hours or more in an H atmosphere, Bristo, a liquid dynamic absorption tester manufactured by Kumagai Riki Kogyo Co., Ltd.
The amount of rearrangement (V) of water was measured using a w tester type II (pressurized type). Then, a 10% by mass aqueous solution of diethylene glycol monobutyl ether was applied to the recording paper surface in an amount of 20 ml /
After applying m ² and drying at 23 ° C. and 55% RH for 1 hour, Bristow measurement was performed in the same manner to determine the amount of water rearrangement (V
a) was obtained and Va / V was calculated.

Then, after the recording paper was treated at 60 ° C. and 20% RH for 24 hours, Bristow measurement was carried out in the same manner as Va measurement to measure the amount of water rearrangement (V60). V60
/ V was calculated. In addition, in the Bristow measurement, in order to improve the measurement accuracy, C.I. I. Acid Red 52 0.
A 05% aqueous solution was used.

(Evaluation of beading after forced deterioration treatment)
Before printing the image on each recording paper, 70 ℃, 20% R
After storing in an H environment for 3 days, the temperature was returned to room temperature, a solid image was output by the method described in Example 1, and forced deterioration treatment was performed according to the same criteria as the beading evaluation described in Example 1. The subsequent beading was evaluated.

Table 2 shows the results obtained as described above.

[0184]

[Table 2]

As is clear from Table 2, the recording paper using the organic particles in the surface layer of the present invention has a lower ink transfer amount by Bristow measurement than the comparative example, and prints similar to the results of Example 1. It can be seen that the difference in glossiness between the printed part and the non-printed part is small, the scratch resistance and the beading property are excellent, and the good beading property is maintained even after the forced deterioration treatment.

Example 3 << Preparation of Inkjet Recording Paper >> (Preparation of Inkjet Recording Paper 1B) In the preparation of recording paper 1 described in Example 1, except that a cationic polymer (P2) was further added as a cationic polymer. In the same manner, recording sheet 1B was produced.

[0187]

[Chemical 8]

(Preparation of Recording Paper 31) On the recording paper 1B prepared above, a coating liquid 31 having the following composition was applied by a wire bar and then dried with warm air at 60 ° C. to prepare recording paper 31. did. The dry film thickness of this newly formed layer was 1 μm.

<Composition of Coating Liquid 31> Dispersion of Organic Particles (Exemplified Compound L1) (Solid Content Concentration: 10% by Mass) 100 g Silica-Cationic Polymer Dispersion 1 20 g (Preparation of Recording Papers 32 to 36) Recording Paper 31 In the preparation of, the type of organic particles of the coating liquid (exemplified compound L2
L4) and the dry film thickness were changed to the conditions shown in Table 3, and recording sheets 32 to 36 were produced in the same manner.

<< Electron Microscopic Observation of Surface and Cross Section of Recording Paper >> The surface of each of the recording papers 31 to 36 produced above was observed with an electron microscope.
It was observed that numerous voids having a pore size of about m were present. Further, when the solid image portion image-formed by the method described in Example 1 was observed in the same manner, it was observed that the organic particles were fused to each other as compared with the unprinted portion.

<Image Output> According to the method described in Example 1, the recording papers 31 to 36 produced above were used to output an image.

<< Evaluation of Output Image Characteristics >> With respect to each of the output images prepared as described above, the gloss difference, scratch resistance and beading were evaluated in the same manner as in Example 1 to obtain the results. The results obtained are shown in Table 3.

[0193]

[Table 3]

As is clear from Table 3, the recording sheets 31 to 36 of the present invention have a small difference in glossiness between the printed portion and the non-printed portion, and are excellent in scratch resistance and beading characteristics, as compared with the comparative examples. I know that

[0195]

INDUSTRIAL APPLICABILITY According to the present invention, an ink jet recording paper for pigment ink, which can reduce the difference in glossiness between a printed portion and a non-printed portion recorded with a pigment ink, eliminates a feeling of strangeness, and obtains an image excellent in scratch resistance. Could be provided.

Claims (3)

[Claims] 1. An SP value of 18.414 to 30.69 (M
Ink jet recording for a pigment ink, having as a surface layer a porous layer containing water-insoluble organic particles, which has a Pa of ^1/2 and is dissolved or swollen by a water-soluble organic solvent having a boiling point of 120 ° C. or higher. Paper. 2. A first porous layer containing at least inorganic particles and a hydrophilic binder as main components, a SP value of 18.414 to 30.69 (MPa) ^1/2 , and a boiling point on a support. Inkjet recording for a pigment ink, characterized in that it has an ink absorbing layer sequentially provided with a second porous layer containing water-insoluble organic particles, which is dissolved or swollen by a water-soluble organic solvent at 120 ° C. or higher. Paper. 3. The average particle size of the organic particles is 5 to 100 n.
The inkjet recording paper for pigment ink according to claim 1 or 2, wherein m is m.