JP2003335045A - Ink jet recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording paper which is good in an ink absorbing property and excellent in an image deterioration-preventive effect (fading resistance) by noxious gas irrespective of storage conditions. <P>SOLUTION: A surface layer containing an organic fine particle A or an organic fine particle B and one or more porous layers are provided on a non- absorbing base material. An inorganic fine particle of ≥20 nm in average particle size of a primary particle is contained in the surface layer to provide the ink jet recording paper. The organic fine particle A is the organic fine particle insoluble in water and soluble in or swollen by a water soluble organic solvent of 18.414-30.69 (MPa)<SP>1/2</SP>in SP value and ≥120°C in boiling point. The organic fine particle B is the organic fine particle having a polymer containing ≥5 mass% of repeating unit represented by general formula (1) as copolymer component. They are an organic fine particle of ≥70°C in glass transition temperature (Tg) and ≤100 nm in average particle size. <P>COPYRIGHT: (C)2004,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 (hereinafter, also simply referred to as a recording paper), and more specifically, it has good ink absorbability and excellent image deterioration preventing effect (fading resistance) due to harmful gas. Inkjet recording paper.

[0002]

2. Description of the Related Art Ink-jet recording is a technique for ejecting minute droplets of ink to adhere to a recording sheet such as paper by various operating principles to record images, characters, etc. It has advantages such as noise and easy multicoloring.

In particular, recently, since the image quality of printers has advanced and has reached the photographic image quality, the recording paper also realizes the photographic image quality, and the texture of the silver salt photograph (gloss, smoothness,
It is required to reproduce).

As one of the methods for reproducing the texture of silver salt photographs, a so-called swelling type in which a hydrophilic binder such as gelatin or polyvinyl alcohol is coated on a support as a recording sheet is known. This method has drawbacks such as a low ink absorption speed, the surface tends to be sticky after printing, and the image is easily blurred due to the influence of humidity during storage. In particular, since the ink absorption speed is slow, the ink droplets mix with each other before they are absorbed, which easily causes bleeding between different colors (bleeding) and color unevenness (beading) within the same color, which makes the silver salt photographic image quality Achievement is very difficult.

The so-called swelling type is becoming the mainstream instead of the swelling type, which is a so-called void type, and is characterized by a high absorption speed because ink is absorbed in fine voids. Examples of the recording paper which achieves the image quality of silver salt photographs and the texture of silver salt photographs as described above are disclosed in JP-A-10-119423 and 10-1.
19424, 10-175364, 10-19.
No. 3776, No. 10-193776, No. 10-217.
No. 601, No. 11-20300, No. 11-10669.
No. 4, No. 11-321079, No. 11-348410.
No. 10-178126, No. 11-348409.
No. 2000-27093, 2000-9483.
0, 2000-158807, 2000-2112
41, etc.

On the other hand, in addition to the image quality and texture, the requirements for durability and image storability have become higher, and many attempts have been made to reach the silver salt photographic level in light resistance, discoloration resistance, moisture resistance, water resistance, and the like. ing. As an example of improving light resistance,
JP-A-57-74192, 57-87989, 57-74193, 58-152072, 64.
-36479, JP-A-1-95091, 1-11
No. 5677, No. 3-13376, No. 4-7189,
7-195824, 8-25796, 11-
321090, 11-277893, JP-A-200
0-37951 and many other techniques have been disclosed.

The void type recording paper has not only the light resistance but also the problem that the void structure is likely to cause discoloration due to harmful gas. In particular, it is likely to occur with a phthalocyanine-based water-based dye used in a general color inkjet printer.

Regarding the technique for improving the phenomenon of discoloration and fading,
For example, JP-A-63-252780 and 64-118.
77, JP-A-1-108083, 1-21-2688.
No. 1, No. 1-218882, No. 1-258980,
2-188287, 7-237348, 7-
No. 266689, No. 8-164664, etc., but since the recording paper of photographic image quality, which has a finer void structure, is more likely to be deteriorated, the conventional improving technique is not effective in improving. It is sufficient and more drastic improvement is desired.

One of the measures against the above problem is to improve by using a swelling type recording paper, but it is very difficult to improve the slow ink absorption speed which is an essential problem. Is.

The ink jet recording method using pigment ink can solve the problem of discoloration to some extent, but the characteristics such as glare (bronzing) on the recording paper have not reached a level at which sufficient image quality can be obtained. The current situation. In addition, as another method, laminating the print or putting it in a frame, etc.
Alternatively, JP-A-53-27426 and JP-A-59-222381.
No. 62-271781, JP-A-11-15720.
7, 11-245507, JP 2000-716.
The method disclosed in No. 08, in which a recording paper containing thermoplastic fine particles on its surface is printed and then subjected to heat or pressure treatment to develop a gas barrier layer, is very effective. Processing is required and extra steps are a burden. In particular, in large-format ink jet recording with a width of 60 cm or more, not only laminating and heat roll processing are troublesome, but also dedicated equipment becomes large,
It is expensive and hard to say that it is widespread.

Further, JP-A-63-60784 discloses an ink jet recording paper having a void layer containing organic fine particles and inorganic fine particles. However, since these organic fine particles are soluble only in a special solvent and not in an organic solvent used in general inkjet printer inks, they cannot be used for ordinary inkjet recording under the present circumstances. is there.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is that ink absorbability is good and the image deterioration preventing effect (fading resistance) due to harmful gas is excellent. It is to provide an inkjet recording paper.

[0013]

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

1. A surface layer containing the organic fine particles A or the organic fine particles B defined above on a non-absorbent support;
An inkjet recording paper having at least one porous layer, wherein the surface layer contains inorganic fine particles having an average primary particle diameter of 20 nm or more.

2. 2. The ink jet recording paper according to item 1, wherein the inorganic fine particles are silica fine particles.

3. 3. The inkjet recording paper according to the above 2, wherein the silica fine particles are vapor phase silica or colloidal silica.

Regarding the mechanism of discoloration, which is the subject of the present invention, all have not been clarified yet, but the porous layer formed on the support has a fine void structure and a high surface area, In addition, since the inorganic fine particles used have an active surface, ozone, oxidant, SOx, NO
It is speculated that a very small amount of active harmful gas in the air such as x decomposes the dye.

The present inventors have previously found that the inclusion of specific organic fine particles in the coating layer of a recording paper is extremely effective in preventing discoloration. In particular, it is effective to make the surface layer contain these organic fine particles at a high concentration.

However, as a result of further studies, it has been found that when the above-mentioned configuration is adopted, the ink absorption speed tends to be lowered, and as a result, mottled unevenness (beading) is likely to occur in the formed image. did.

As a result of intensive studies on the above problems, the inventors of the present invention prevent the discoloration by including inorganic fine particles having an average primary particle diameter of 20 nm or more in the surface layer together with specific organic fine particles. It has been found that it is possible to provide an inkjet recording paper which is excellent in effect and ink absorbency. Although the detailed mechanism is unknown, in general, a void layer filled with organic fine particles has a low porosity and tends to have a low ink absorption rate. In the surface layer composed only of organic fine particles, the organic solvent in the printed ink swells, and the dissolved organic fine particles are fused to each other, which has the effect of blocking harmful gas that is considered to cause discoloration, but as described above. It is considered that since the surface layer has a low porosity, and the organic fine particles swell and dissolve when printed, the ink absorption rate is hindered. Therefore, the present inventors have found that the organic fine particles and the inorganic fine particles specified in the present invention are contained in the surface layer to prevent the fusion of the organic fine particles with each other and reduce the ink absorbability. . Furthermore, when the average particle size of the inorganic fine particles is 20 nm or more, the void ratio formed by the organic fine particles and the inorganic fine particles becomes high, and it was found that an ink jet recording paper having high ink absorbency can be provided, and the present invention was achieved. Is.

The details of the present invention will be described below. In the present invention, a surface layer containing organic fine particles A or organic fine particles B defined below on a non-absorbent support, and 1
An inkjet recording paper having a porous layer of two or more layers is characterized in that the surface layer contains inorganic fine particles having an average primary particle diameter of 20 nm or more.

First, the details of the organic fine particles A and the organic fine particles B according to the present invention will be described.

The organic fine particles A according to the present invention are insoluble in water which has an SP value of 18.414 to 30.69 (MPa) ^1/2 and is dissolved or swollen by a water-soluble organic solvent having a boiling point of 120 ° C. or higher. Of organic fine particles having a glass transition temperature (Tg) of 70 ° C. or higher and an average particle diameter of 100 nm or less.

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 are used.
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.

The organic fine particles A according to the present invention have an SP value of 1
8.414-30.69 (MPa) ^1/2And the boiling point is
Dissolved or swollen by the water-soluble organic solvent above 120 ° C
Water-insoluble organic fine particles and glass transition temperature
(Tg) is 70 ° C. or higher, and average particle size is 100 nm or less
And has a weight average molecular weight of 50.
A polymer of 00 or more is preferable, and its material is, for example,
For example, polyvinyl chloride, polyvinylidene chloride, polyacrylic
Rate, polymethacrylate, elastomer, ethylene
-Vinyl acetate copolymer, styrene- (meth) acrylic copolymer
Polymer, polyester, polyvinyl ether, polyvinyl
Luacetal, polyamide, polyurethane, polyolefin
In, SBR, NBR, polytetrafluoroethylene,
Chloroprene, protein, polysaccharide, rosin ester,
It is selected from conventionally known ones such as shellac resin. Especially good
The material of the organic fine particles A is preferably polyvinyl acetal.
Resin, polyurethane resin, rosin ester resin,
(Meth) acrylate resin, SBR, etc.
Resins composed of two or more monomers by copolymerization are also preferred.
Used with a specific modifying group added to the resin
It is also possible to remove the leaving group or a mixture of two or more materials.
To form organic fine particles, and more than two kinds
You may mix and use an organic fine particle.

"Dissolve in an organic solvent" in the present invention
Means that the organic fine particles A and the water-soluble organic solvent in the ink form a single phase in an equilibrium state, and "swells with the organic solvent" means that the organic fine particles A absorb the same water-soluble organic solvent. To increase the volume. The preferred volume increase rate when swollen is 2 to 8 times.

The organic fine particles A according to the present invention must be insoluble in water because they do 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. 2 for the mass of the organic fine particles A
It may absorb up to 0% by weight of water. Further, the organic fine particles A according to the present invention need only be contained in such an amount that the organic fine particle A-containing layer is softened after printing with a pigment ink, but preferably 50% by mass or more based on the solid content in the layer. And more preferably 75% or more.

Further, a crosslinking agent may be used in the organic fine particles A according to the present invention in 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 average particle size of the organic fine particles A according to the present invention greatly affects the surface gloss of recording paper. One feature of the present invention is that it is 100 nm or less, but a preferable average particle diameter is 1 to 100 nm, and more preferably 5 to 100 nm. When the average particle diameter of the organic fine particles A is 5 to 100 nm, it can 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 of measuring the average particle diameter, for example, the cross section or the surface of the organic fine particle-containing layer is observed with an electron microscope, the particle diameters of a large number of arbitrary organic fine particles A are calculated, and the simple average value (number average) thereof 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 fine particles A 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 fine particles A according to the present invention does not have to be a spherical shape, and may be needle-like or plate-like. The particle size is calculated from the volume in terms of sphere.

Next, the organic fine particles B according to the present invention will be described. The organic fine particles B referred to in the present invention means that the repeating unit represented by the general formula (1) is used as a copolymer component.
Having a polymer content of not less than mass%, having a glass transition temperature (Tg) of not less than 70 ° C., and an average particle diameter of 100 nm
The following organic fine particles are defined.

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

[0037]

[Chemical 2]

[0038]

[Chemical 3]

[0039]

[Chemical 4]

The hydrophilicity is imparted to the repeating unit represented by the general formula (1) in each partial structure of X, J and the substituent Y forming the general formula (1). However, in the present invention, it is preferable that the substituent Y imparts hydrophilicity.

As the substituent used for imparting hydrophilicity to the repeating unit represented by the general formula (1), "Structure-activity relationship of drug (guideline for drug design and mode of action)" (Chemical region special issue No. 122) Structure-activity relationship social gathering, edited by Nankodo (1980), p96 to 103, a hydrophobic parameter (π) has a negative substituent, and the like.

The organic fine particles B according to the present invention must contain the specific repeating unit represented by the general formula (1) as a copolymerization component in an amount of 5% by mass or more, but 10% by mass or more is contained. Preferably.

The organic fine particles B themselves are preferably hydrophilic but not water-soluble, so that 10
It is preferable to adjust the content in the range of less than 50% by mass.

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

[0045]

[Chemical 5]

[0046]

[Chemical 6]

On the other hand, as the other monomer component of the polymer constituting the organic fine particles B, 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,
Alternatively, 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,
Examples thereof include di (t-butyl) aminohexyl acrylate. Of these, styrene, methyl methacrylate and n-butyl acrylate are preferably used.

The organic fine particles B 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 equal to or nonionic with the coating solution. preferable. The ionicity of the coating liquid for the layer containing the organic fine particles B is
It is preferably equal to or nonionic with the ionicity of the coating liquid of the other layer. Most preferably, the organic fine particles B and the coating liquid are all ionic or cationic.

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 environment. Therefore, the glass transition temperature (Tg) of the organic fine particles B needs to be 70 ° C. or higher, preferably 80 ° C. or higher, and more preferably 90 ° C. to 120 ° C.

When the glass transition temperature (Tg) of the organic fine particles A and the organic fine particles B is less than 70 ° C., fusion of the organic fine particles is likely to occur due to heating, and as a result, voids on the surface of the recording paper are generated. It is reduced or decreased, and the ink absorption speed is likely to be reduced.

Here, the Tg of the polymer which is a constituent component of the organic fine particles according to the present invention is calculated by the mass fraction from the Tg of the monomer homopolymer as a 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 WILEY-INTERSC
Many measurement values are published in IENCE PUBLICATION).

The average particle size of the organic fine particles B is 100.
It is necessary to be less than or equal to nm, but preferably 60 n
m or less, more preferably 20 to 40 nm, and the organic fine particles B according to the present invention are preferably synthesized in water by a conventionally known emulsion polymerization method or the like. The particle diameter is from about 20 nm to 100 nm according to a conventionally known method such as adjusting the kind and amount of the emulsifier and the monomer component.
It can be adjusted to a range of up to a degree.

In order to exert the effect of the present invention remarkably, the organic fine particles A or B are used as the surface layer arranged on the surface of the porous layer.
The content is preferably 50 to 90% by mass, and it is described below from the viewpoint of effectively preventing the fusion of organic fine particles in the surface layer and further increasing the ink absorption rate in the present invention. The content of the inorganic fine particles is preferably 10 to 50% by mass.

Next, the inorganic fine particles used in the surface layer will be described. Examples of the inorganic fine particles that can be used in the present invention 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, magnesium hydroxide, etc. Examples thereof include white inorganic pigments.

The average particle size of the inorganic fine particles is characterized by having a primary particle size of 20 nm or more, but the measuring method is to observe the particles themselves with an electron microscope to obtain 1,000.
The particle diameter of each arbitrary particle is measured, and it is calculated as a simple average value (number average). Here, the particle size of each particle is
It is represented by the diameter assuming a circle equal to the projected area.

As the inorganic fine particles, solid fine particles selected from silica and alumina or alumina hydrate are preferably used, but in the invention according to claim 2, silica fine particles are preferable from the viewpoint of low cost.

As the silica that can be used in the present invention, silica synthesized by an ordinary wet method, colloidal silica, silica synthesized by a vapor phase method and the like are preferably used, and fine particles particularly preferably used in the present invention. As the silica, colloidal silica or fine particle silica synthesized by a vapor phase method is preferable, and in the invention according to claim 3, the silica fine particles are vapor phase method silica or colloidal silica to obtain high reflection density and transparency. From the viewpoint of being preferable. Further, in the present invention, vapor-phase process silica or colloidal silica subjected to cation surface treatment can also be used.

The inorganic fine particles are characterized by having a particle size of 20 nm or more. For example, in the case of fine particle silica synthesized by the gas phase method, the primary particles of the inorganic fine particles dispersed in the state of primary particles are used. The average particle size (particle size in a dispersion state before coating) is preferably 20 to 100 nm, and by using inorganic fine particles having a particle size in this range,
The glossiness of the recording paper becomes good.

The most preferably used silica synthesized by the gas phase method having an average primary particle diameter of 20 to 100 nm is, for example, Aerosil manufactured by Nippon Aerosil Co., Ltd., ST series manufactured by Nissan Chemical Industries, Ltd., or the like. It is commercially available. This gas phase method fine particle silica is easily sucked and dispersed in water, for example, by a jet stream inductor mixer manufactured by Mitamura Riken Kogyo Co., Ltd.
The primary particles can be dispersed relatively easily.

The content of the inorganic fine particles in the surface layer is 10
It is preferably from mass% to 50 mass%.

The ink jet recording paper of the present invention is characterized by having a surface layer containing the organic fine particles A or organic fine particles B and inorganic fine particles. The surface layer in the present invention is the outermost surface. The layer is not limited to any particular layer, and is not particularly limited as long as the effect of the present invention is exhibited.

Preferred constitutional examples for clearly showing the surface layer in the present invention are listed below. The layer constitution according to the present invention is as follows.
It is not limited to these.

1: Structure having a void-type ink absorption layer on a support, and a layer containing organic fine particles A or organic fine particles B and inorganic fine particles thereon is the outermost layer 2: void on the support 3 has a type ink absorbing layer, a layer containing organic fine particles A or organic fine particles B and inorganic fine particles is provided thereon, and a thin layer is further provided thereon for the purpose of improving surface physical properties. : A layer having a void-type ink absorbing layer on a support, a layer containing organic fine particles A or organic fine particles B and inorganic fine particles is provided thereon, and ultraviolet rays are further provided thereon for the purpose of cutting harmful light. Configuration 4 in which a thin layer having an absorbing function is provided: A void-type ink absorbing layer is provided on a support, and a layer containing organic fine particles A or organic fine particles B and inorganic fine particles is provided thereon, and further on top of that. Structure 5 in which a layer containing a matting agent is provided on the substrate: void type on the support It has ink absorbing layer, a layer that contains the organic fine particles A or organic particles B and the inorganic fine particles thereon is provided, further thereon, structure in which a peelable layer.

The most preferable constitution among the constitution examples described above is the case where the containing layer of the organic fine particles A or the organic fine particles B and the inorganic fine particles according to the item 1 which can most exert the effect of the present invention is the outermost layer. .

The surface layer containing the organic fine particles A or the organic fine particles B and the inorganic fine particles according to the present invention may contain a binder component or the like.

Next, a porous layer (also called an ink absorbing layer)
Will be described. The inkjet recording paper of the invention has one or more porous layers, so-called ink absorbing layers.

Generally, the ink absorbing layer is roughly classified into a swelling type and a void type. As the swelling type, a water-soluble binder is used and, for example, gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide or the like is applied alone or in combination, and this is used as an ink absorbing layer.

As the void type, fine particles and a water-soluble binder are mixed and applied, and those having gloss are particularly preferable. As fine particles, alumina or silica is preferable, and silica having a particle diameter of 0.1 μm or less is particularly preferable. As the water-soluble binder, gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide and the like are preferably used alone or in combination.

Of the above two types, the one having a high ink absorption speed of the recording paper is suitable for adapting to continuous high speed printing. From this point, the void type is particularly preferably used in the present invention. it can.

The void type ink absorbing layer will be described in more detail below. The void layer is mainly formed by soft aggregation of the hydrophilic binder and the inorganic fine particles. Conventionally, various methods for forming voids in a film are known,
For example, a method of applying a uniform coating solution containing two or more kinds of polymers on a support, and phase-separating these polymers in a drying process to form voids, solid fine particles and a hydrophilic or hydrophobic resin After coating the coating liquid containing it on a support and drying it, the ink jet recording paper is immersed in water or a liquid containing an appropriate organic solvent to dissolve solid fine particles to form voids, and foaming is performed during film formation. After applying a coating solution containing a compound having properties, a method of foaming this compound in the drying process to form voids in the coating, and a coating solution containing porous solid fine particles and a hydrophilic binder is applied on a support. Then, a method for forming voids in the porous fine particles or between the fine particles, solid fine particles and / or fine particle oil droplets and hydrophilic binder having a volume that is approximately equal to or more than that of the hydrophilic binder. The coating liquid containing coated on a support, and a method of forming an air gap between the solid particles are known. In the present invention, the void layer has an average particle size of 10
It is particularly preferable that it is formed by containing various inorganic solid fine particles of 0 nm or less.

Examples of the inorganic fine particles which can be used in the present invention 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 Examples thereof include white inorganic pigments such as alumina, pseudo-boehmite, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide and the like.

The average particle size of the inorganic fine particles is obtained by observing the particles themselves with an electron microscope, measuring the particle size of 1,000 arbitrary particles, and obtaining the simple average value (number average). Here, the particle size of each particle is represented by the diameter assuming a circle equal to the projected area.

As the inorganic fine particles, solid fine particles selected from silica and alumina or alumina hydrate are preferably used, but silica is more preferable.

As silica which can be used in the present invention, silica synthesized by a usual wet method, colloidal silica, silica synthesized by a vapor phase method and the like are preferably used, and fine particles particularly preferably used in the present invention. As silica, colloidal silica or fine particle silica synthesized by a vapor phase method is preferable, and silica is particularly preferably silica synthesized by a vapor phase method.

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

The inorganic fine particles are 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 the present invention, a water-soluble binder can be used in the ink absorbing layer. Examples of the water-soluble binder that can be used in the present invention 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 binders in combination.

The water-soluble binder preferably used in the present invention is polyvinyl alcohol.

The polyvinyl alcohol preferably used in the present invention includes, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, polyvinyl alcohol having a cation-modified terminal 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 1,000 or more are preferably used, and particularly, the average degree of polymerization is 1,500 to
Those of 5,000 are preferably used. Further, the saponification degree is preferably 70 to 100%, 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 may 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.

Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl). ) Ammonium chloride, N-vinylimidazole, N-vinyl-2-methylimidazole, N
-(3-dimethylaminopropyl) methacrylamide,
Hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1,1-dimethyl-3-)
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 described in, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-206088 and JP-A-61-237681 and 63-307979. Such a copolymer of vinyl alcohol and a vinyl compound having a water-soluble group, and JP-A-7-285.
The modified polyvinyl alcohol which has a water-soluble group as described in No. 265 is mentioned.

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 vinyl alcohol as described in 1. Polyvinyl alcohol can be used in combination of two or more types such as different degree of polymerization or 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,
Generally depends on the type of inorganic pigment and the type of water-soluble binder, but generally 5 to 3 per 1 m ^{2 of} recording paper.
It is 0 g, preferably 10 to 25 g.

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

In the ink jet recording paper of the present invention, a cationic polymer is preferably used for the purpose of preventing image bleeding due to storage after recording.

Examples of the cationic polymer 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, cationized starch, vinylbenzyltrimethylammonium chloride polymer, (2-methacryloyloxyethyl) trimethylammonium chloride polymer,
Examples thereof include dimethylaminoethyl methacrylate polymer.

The Chemical Industry Bulletin August 15, 1998,
Examples include the cationic polymer described on 25th, and the polymer dye fixing agent described in "Introduction to Polymeric Drugs" issued by Sanyo Chemical Industries, Ltd.

The amount of the cationic water-soluble polymer added is
Usually 0.1 to 10 per 1 m ^{2 of} inkjet recording paper
g, preferably in the range of 0.2-5 g.

In the void layer, the total amount of voids (void volume)
Is preferably 20 ml or more per 1 m ² of recording paper. If the void volume is less than 20 ml / m ^{2 and} the ink amount during printing is small, the ink absorbability is good, but if the ink amount is large, the ink is not completely absorbed, and the image quality may deteriorate. Problems such as delayed drying tend to occur.

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.

As another type of void type, a polyurethane resin emulsion, water-soluble epoxy compound and /
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 present invention, it is preferable to use a curing agent. The curing agent can be added at any time during the production of the inkjet recording paper, and for example, may be added to the coating liquid for forming the ink absorption layer.

In the present invention, the method of supplying the curing agent for the water-soluble binder after the formation of the ink absorbing layer may be used alone, but the above-mentioned curing agent is preferably used in the coating liquid for forming the ink absorbing layer. It is to be used in combination with the method of adding to.

The curing agent that can be used in the present invention is not particularly limited as long as it causes a curing reaction with a water-soluble binder, but boric acid and salts thereof are preferable, but other known agents are used. In general, a compound having a group capable of reacting with a water-soluble binder or a compound that promotes a reaction between different groups of the water-soluble binder, and is appropriately selected and used according to the type of the water-soluble binder. To be Specific examples of the curing agent include, for example,
Epoxy curing agent (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 curing agents (formaldehyde, glyoxal, etc.), active halogen curing agents (2,4-dichloro-4-)
Hydroxy-1,3,5, -s-triazine etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether etc.), aluminum alum and the like.

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 and octaboric acid and their salts are mentioned.

The boric acid having a boron atom and its salt as a curing agent may be used as a single aqueous solution or as a mixture of two or more kinds. Particularly preferred is a mixed aqueous solution of boric acid and borax.

The aqueous solutions of boric acid and borax can be added only in relatively dilute aqueous solutions, but by mixing them, a concentrated aqueous solution can be obtained and the coating solution can be concentrated. . Further, there is an advantage that the pH of the aqueous solution to be added can be controlled relatively freely. The total amount of the curing agent used is the above water-soluble binder 1
1 to 600 mg per g is preferred.

Various additives other than those described above can be used in the ink absorbing layer of the ink jet recording paper 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 , Anionic, cationic, nonionic and amphoteric surfactants, JP-A-57-74
193, 57-87988 and 62-2614.
UV absorbers described in JP-A-76-74192.
No. 57-87989, No. 60-72785, No. 61-146591, No. 1-95091 and No. 3-13376, and anti-fading agents, JP-A-59-42993, 59-52689, 62
-280069, 61-242871, JP-A-4-219266 and the like, fluorescent whitening agents, sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, pH adjusting agents such as potassium carbonate , Antifoam, antiseptic,
Various known additives such as a thickener, an antistatic agent and a matting agent 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, a non-water-absorbing support which has heretofore been known for ink jet recording paper can be used. That is, since a large amount of the water-soluble organic solvent in the ink remains in the recording paper in the case of the non-water-absorbent support than in the case of the water-absorbent support, it effectively acts on the dissolution of organic fine particles and the like. It is estimated that the effects of the present invention can be remarkably exhibited.

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.

As the opaque support, for example, 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, etc. 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 before 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-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 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 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 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, which 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 treatment when polyethylene is melt-extruded on the surface of a raw paper for coating, and a matte surface or a silk surface obtained by ordinary photographic printing paper. 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 kinds of ink absorbing layers, such as a surface layer and a porous layer constituting the recording paper of the present invention, and an undercoat layer, which are appropriately provided as necessary, to a non-water-absorbing support is
It can be performed by appropriately selecting from known methods. A preferred method is obtained by applying a coating solution forming each layer on a support and drying.

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.

In image recording using the ink jet recording paper of the present invention, a recording method using water-based ink is preferable.

The aqueous ink used in the present invention means a recording liquid containing the following colorant, liquid medium and other additives.

As the colorant that can be used in the present invention, use is made of a water-soluble dye or a water-dispersible pigment such as a direct dye, an acid dye, a basic dye, a reactive dye, a food dye and the like, which are well known in ink jet. You can Among them, a particularly preferable colorant is an ink using a phthalocyanine dye as a cyan dye. Phthalocyanine dyes are particularly widely known and used among cyan dyes.

As the solvent for the aqueous ink, water and various water-soluble organic solvents, for example, alcohols such as methyl alcohol, i-propyl alcohol, butyl alcohol, t-butyl alcohol and i-butyl alcohol; dimethylformamide and dimethyl are used. Amides such as acetamide;
Ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1, 2, 6-hexanetriol, thiodiglycol, hexylene glycol,
Polyhydric alcohols such as diethylene glycol, glycerin, triethanolamine; ethylene glycol methyl ether, diethylene glycol methyl (or ethyl)
Examples thereof include lower alkyl ethers of polyhydric alcohols such as ether and triethylene glycol monobutyl ether.

Among these water-soluble organic solvents, polyhydric alcohols such as diethylene glycol, triethanolamine and glycerin, and lower alkyl ethers of polyhydric alcohol such as triethylene glycol monobutyl ether are preferable.

Other additives for the water-based ink include, for example, pH adjusting agents, sequestering agents, antifungal agents, viscosity adjusting agents,
Surface tension adjusting agents, wetting agents, surfactants, rust preventives and the like can be mentioned.

In order to improve the wettability with respect to the recording paper, the aqueous ink liquid is 25-60 mN / at 20 ° C.
It is preferable to have a surface tension in the range of m, preferably 30 to 50 mN / m.

The printer that can be used in the present invention is not particularly limited as long as it has a recording paper accommodating portion, a conveying portion, an ink cartridge and an ink jet print head, like a commercially available printer. At least a roll-shaped recording paper storage unit, transport unit,
It is preferable that the printer set includes an inkjet print head, a cutting unit, and if necessary, a heating unit, a pressure unit, and a recording print storage unit. The inkjet print head used may be an on-demand type or a continuous type. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electric-heat conversion method (for example, a thermal type Examples thereof include an inkjet type, a bubble jet (R) type, an electrostatic suction type (for example, an electric field control type, a slit jet type, etc.), and a discharge type (for example, a spark jet type). The electro-mechanical conversion method is preferred, but any ejection method may be used.

[0127]

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

<< Preparation of Recording Sheets >> Recording Sheets 1 to 20 were prepared according to the following procedure.

[Preparation of Recording Paper 1] On a paper support (thickness: 230 μm) coated on both sides with polyethylene, a liquid temperature of 45
After coating the following porous layer coating liquid 1 at 40 ° C with a wire bar and drying, 12 in a constant temperature bath at 40 ° C and 80% RH.
It was stored for a time to obtain a recording sheet 1. Dry film thickness is 35 μm
Met. The amount of silica fine particles applied to the recording paper 1 was 15 g / m ² , the amount of cationic polymer (P1) applied was 2.2 g / m ² , and the amount of polyvinyl alcohol applied was 2.
It was 3 g / m ² .

(Preparation of Porous Layer Coating Solution 1) Silica
The cationic polymer dispersion liquid 1 was heated to 45 ° C., a 10% aqueous solution of polyvinyl alcohol (Kuraray, PVA203) and other polyvinyl alcohol (Kuraray, PVA2) were used.
The 6% aqueous solution of 45) was added to each after raising the temperature to 45 ° C. Finally, pure water at 45 ° C. was added so as to have a constant volume to obtain a semi-transparent porous layer coating liquid 1.

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

[Preparation of Recording Paper 2] On the porous layer of the recording paper 1 prepared above, fine particle silica having an average particle diameter of 12 nm (QS-20 manufactured by Tokuyama Corp.) and an acrylic emulsion (Tg = -30 ° C.) , And an average particle diameter of 30 nm).
75 g / m ² , acrylic emulsion is 0.05 g /
m ² and so as the coating, and dried to obtain a recording paper 2.

[Preparation of Recording Paper 3] On the porous layer of the recording paper 1 prepared above, an organic fine particle emulsion (Exemplified Compound L1) and fine particle silica having an average primary particle diameter of 7 nm (manufactured by Tokuyama Corp., QS- 30) and an acrylic emulsion (Tg = −30 ° C., average particle size 30 nm) for the surface layer coating solution 3 with a wire bar, and the organic fine particle emulsion (exemplary compound L1) has a solid content of 0.5 g / m 2.
^2, particulate silica is 0.25 g / m ^2, coating to an acrylic emulsion is 0.05 g / m ^2, and dried to obtain a recording sheet 3.

[Production of Recording Papers 4 to 15] In the production of the above-mentioned recording paper 3, the kinds of organic fine particles and inorganic fine particles used in the surface layer were changed to the combinations shown in Table 1 in the same manner. Recording sheets 4 to 15 were prepared.

The details of each inorganic fine particle shown in Table 1 are as follows. QS-20: Fine particle silica having an average particle diameter of 12 nm Tokuyama QS-30: Fine particle silica having an average particle diameter of 7 nm Tokuyama A-50: Fine particle silica having an average particle diameter of 30 nm AER
OSIL50 Nippon Aerosil Co., Ltd. ST-XL: Fine particle silica with an average particle size of 50 nm Nissan Chemical Co., Ltd. ST-ZL: Fine particle silica with an average particle size of 85 nm Nissan Chemical Co., Ltd.

[0136]

[Chemical 7]

[Preparation of Recording Paper 16] On the porous layer of the prepared recording paper 1, the following organic fine particle emulsion (L10) had a solid content of 0.5 g / m ² and an acrylic emulsion (Tg = −30 ° C.). , Average particle size 30n
A surface layer coating solution containing m) as solid content of 0.05 g / m ² was applied using a wire bar and dried to obtain a recording paper 16.

(Preparation of Organic Fine Particle Emulsion (L10)) Using the monomer of n-butyl methacrylate: styrene: 2-hydroxyethyl methacrylate = 10: 65: 25 (mass ratio), emulsion polymerization was carried out according to a known method to obtain an organic compound. A fine particle emulsion (L10) was prepared. The surfactant used in the above preparation is stearyl trimethyl ammonium chloride which is a cationic surfactant,
3 mass% was added as solid content with respect to the total amount of monomers.
The organic fine particle emulsion (L
The average particle diameter of the organic fine particles contained in 10) was 50 nm as measured by a laser scattering method, and the glass transition temperature (Tg) calculated from the Tg of each constituent monomer by the above method was 72 ° C. Met.

[Preparation of recording paper 17] Recording prepared as described above
The organic fine particle emulsion is formed on the porous layer of the paper 1.
(L10) is 0.5 g / m as solid content², Primary particles
Fine particle silica having an average particle diameter of 12 nm (manufactured by Tokuyama Corporation,
QS-20) is 0.25g / m², Acrylic emulsion
(Tg = -30 ° C, average particle size 30 nm) is solid content
0.05g / m as quantity ²The surface layer coating liquid consisting of
A recording paper 17 was obtained by applying and drying using a bar.

[Preparation of Recording Paper 18] Recording Paper 17
In the preparation of, the average particle size of the primary particles was 3 instead of the fine particle silica (QS-20 manufactured by Tokuyama Corp.) used in the surface layer.
Recording paper 1 was used in the same manner except that fine particle silica of 0 nm (AEROSIL50 manufactured by Nippon Aerosil Co., Ltd.) was used.
Got 8.

[Preparation of Recording Papers 19 and 20] Recording was carried out in the same manner as in preparation of the recording papers 17 and 18 except that the following organic fine particle emulsion (L11) was used instead of the organic fine particle emulsion (L10). Paper 1
9 and 20 were produced.

(Preparation of Organic Fine Particle Emulsion (L11)) Using a monomer of t-butyl methacrylate: styrene: 2-hydroxyethyl methacrylate = 30: 45: 15 (mass ratio), emulsion polymerization was carried out according to a known method to obtain an organic compound. A fine particle emulsion (L11) was prepared. The surfactant used for the above-mentioned preparation was Emulgen 220 (manufactured by Kao), and was added in a solid content of 5% by mass with respect to the total amount of the monomers. The average particle size of the organic fine particles contained in the organic fine particle emulsion (L11) prepared as described above was 40 nm as measured by a laser scattering method,
The glass transition temperature (Tg) calculated from the Tg of each constituent monomer by the above-mentioned method was 103 ° C.

[Solubility Test of Organic Fine Particles] The organic fine particle emulsions (L10) and (L11) used in the preparation of the recording papers 16 to 20 were mixed with diethylene glycol monobutyl ether [SP value 19.437 (MPa) ^1/2]. ,
As a result of mixing with a boiling point of 230 ° C.] at room temperature, all were dissolved.

[Electron Microscopic Observation of Surface and Cross Section of Recording Paper] (Observation of Surface and Cross Section of Untreated Recording Material) The surface of each of the recording papers 1 to 20 prepared above was observed with an electron microscope.
Innumerable voids having a diameter of about 5 nm to 100 nm were present.

(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 20 subjected to the following treatment A with an electron microscope revealed that the recording papers 2 to 15 were: It was observed that the voids were reduced or decreased as compared with the unrecorded portion, and in the recording papers 16 to 20, a state in which the organic fine particles were melted or swollen and thus fused with each other was observed.

[0146] <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 20. 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.

<< Preparation of Ink Liquid >> A cyan ink liquid having the following composition was prepared.

Water 68.5 parts Diethylene glycol monobutyl ether 12 parts Diethylene glycol 10 parts Glycerin 8 parts C.I. I. Direct Blue 86 1 part Surfactant (Shin-Etsu Chemical's Surfynol 465) 0.5 part <Inkjet image printing and evaluation> (Image printing) Ink jet printer M
Mounted on J-800C (manufactured by Seiko Epson Corporation),
Cyan solid images were printed on the recording sheets 1 to 20 by changing the ink ejection amount. This image was dried in an environment of 23 ° C. and 55% RH for 1 hour.

(Evaluation of Printed Image) Each image printed as described above was evaluated according to the following methods.

<Evaluation of beading resistance (mottled spot resistance)> The cyan solid image printed portion formed by changing the ink ejection amount of each recording paper was visually observed, and beading was evaluated according to the following criteria. .

O: No mottled unevenness is observed at all in the ink ejection amount region. Δ: Mottled unevenness is observed only in the portion where the ink ejection amount is large. X: All regions including the ink ejection amount are small. In the region, the level at which mottled unevenness is observed and which has no practical problem is ◯ or Δ.

<Evaluation of Fading Resistance> Each of the cyan solid printed image portions printed on each recording sheet was attached to a window in an office room, and left for 6 months in an environment exposed to the outside air but not exposed to direct sunlight. Printing part before and after leaving (density 1.0
(Part), the density of the reflection was measured with monochromatic light of red, and the residual density ratio was obtained according to the following formula, and this was used as a measure of resistance to fading.

Percentage of remaining concentration = (concentration after standing for 6 months / concentration before standing) × 100 (%) Table 1 shows the results obtained above.

[0154]

[Table 1]

As is clear from Table 1, the recording paper of the present invention containing the organic fine particles A or B defined in the present invention and the inorganic fine particles having an average particle diameter of 20 nm or more in the surface layer is the same as the ink of Comparative Example. Good absorption (beading resistance),
In addition, it can be seen that the image has excellent resistance to fading due to harmful gas (air oxidation).

[0156]

According to the present invention, it is possible to provide an ink jet recording paper which has a good ink absorbency (beading resistance) and an excellent effect of preventing image deterioration due to harmful gas (fading resistance).

Claims (3)

[Claims] 1. An inkjet recording paper having a surface layer containing organic fine particles A or organic fine particles B defined below and one or more porous layers on a non-absorbent support, and primary particles are provided on the surface layer. An inkjet recording paper, characterized by containing inorganic fine particles having an average particle diameter of 20 nm or more. Organic fine particles A: SP value is 18.414 to 30.69 (M
Pa) ^1/2 and water-insoluble organic fine particles that dissolve or swell in a water-soluble organic solvent having a boiling point of 120 ° C. or higher, have a glass transition temperature (Tg) of 70 ° C. or higher, and have an average particle size of 100 nm or less. Organic fine particles. Organic fine particles B: having a polymer containing 5% by mass or more of a repeating unit represented by the following general formula (1) as a copolymerization component, having a glass transition temperature (Tg) of 70 ° C. or higher, and an average particle diameter of 100 nm. The following organic particles. [Chemical 1] [In the formula, X represents -O- or -N (R ₂ )-, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and X represents Is -O-, J is an alkylene group having 2 to 8 carbon atoms and optionally having an ether structure or a thioether structure,
Y represents a hydroxyl group, an alkoxyl group or a carbamoyl group, and when X is —N (R ₂ ) —, J may have a single bond or an ether structure or a thioether structure having 2 to 8 carbon atoms. A good alkylene group, Y
Represents a hydrogen atom, a hydroxyl group, an amino group, an alkoxyl group or a carbamoyl group. ] 2. The ink jet recording paper according to claim 1, wherein the inorganic fine particles are silica fine particles. 3. The ink jet recording paper according to claim 2, wherein the silica fine particles are vapor phase silica or colloidal silica.