JP2000094830A - Ink jet recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cracks, and improve the water-resistance, the gloss property and the productivity by mixing a cationic polymer-containing liquid and an inorganic particle dispersion liquid which disperses to the state of a primary particle, then, adding a water-soluble polymer to form an application liquid, and applying the application liquid on a supporting body. SOLUTION: A cationic polymer is preferably a single polymer of a monomer having a quarternary ammonium salt group, or a copolymer with other one, or two or more monomers which can be copolymerized. As an inorganic particle, silica which has a low index of refraction and is excellent in transparency is preferably used. In such a cationic polymer solution, an inorganic particle dispersion liquid which disperses to a primary particle, and of which the average particle diameter is approx. 4-20 nm, is gradually added while sufficiently stirring, and mixed, and then, gelatin (preferably an acid treated gelatin) as a water-soluble polymer, polyvinyl pyrrolidone the average molecular weight is preferably approx. 200,000 or higher) or the like are added, and an application liquid is obtained, and the application liquid is applied on a supporting body without a mechanical dispersion.

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 particularly to an ink jet recording paper which is excellent in water resistance, ink absorbency, glossiness and can improve productivity. Regarding paper.

[0002]

2. Description of the Related Art Ink-jet recording is a method in which fine droplets of ink are caused to fly according to various operating principles and adhere to a recording sheet such as paper to record images and characters. It has advantages such as easy noise and multicoloring.

[0003] With regard to nozzle clogging and maintenance, which has been a problem in the conventional recording method, improvements have been made in both the ink and the device. At present, various fields such as various printers, facsimile machines, and computer terminals are rapidly being developed. It is widespread.

The recording paper used in this ink jet recording method has a high density of print dots, a bright and vivid color tone, and the ink absorbs quickly so that even if the print dots overlap, the ink may flow out. It is required that bleeding does not occur, that the diffusion of print dots in the horizontal direction is not unnecessarily large, and that the periphery is smooth and not blurred.

In particular, when the ink absorption speed is low, when ink droplets of two or more colors are recorded in an overlapping manner, the droplets cause a repelling phenomenon on the recording paper to become uneven, It is necessary for recording paper to have a high ink absorbency because the colors of each other are blurred in the boundary region of, and the image quality is easily deteriorated.

[0006] To solve these problems, a great many techniques have been proposed.

For example, a recording paper described in JP-A-52-53012 in which a coating material for surface processing is wetted on a low-size base paper, and a support surface described in JP-A-55-5830 is used. Recording paper provided with an ink-absorbing coating layer, recording paper containing non-colloidal silica powder as a pigment in a wearable layer described in JP-A-56-157,
JP-A-57-107878 describes a recording paper in which an inorganic pigment and an organic pigment are used in combination.
No. 87, a recording paper having two pore distribution peaks, a recording paper comprising two upper and lower porous layers described in JP-A-62-111782,
Nos. 9-68292, 59-123696 and 6
Recording paper having irregular cracks described in JP-A Nos. 0-18383 and 61-135786, 6
Recording papers having a fine powder layer described in JP-A-1-148092 and JP-A-62-149475, JP-A-63-252779, JP-A-1-108083, JP-A-2-136279, JP-A-3-65376. No. and 3-
No. 27976, a recording paper containing a pigment having specific physical properties and fine particle silica,
No. 14091, No. 60-219083, No. 60-21
No. 0984, No. 61-20797, No. 61-1881
No. 83, JP-A-5-278324, JP-A-6-92011
No. 6-183134, No. 7-137431, No. 7-276789, and the like, and recording paper containing fine particle silica such as colloidal silica, and JP-A-2-276671, JP-A-3-27671. 67684, 3-
No. 215082, No. 3-251488, No. 4-679
Nos. 86, 4-263983 and 5-16517
There are many known recording papers and the like containing alumina hydrate fine particles described in Japanese Unexamined Patent Publication (Kokai) No. H10-15064.

On the other hand, in ink-jet recording, various methods for fixing a dye by adding a cationic substance to an ink receiving layer in order to improve the water resistance of an obtained image are used.

However, in the ink receiving layer having the void structure, when the substance forming the void structure is cationic inorganic fine particles, it is difficult to form a high void ratio as in cationic colloidal silica. Alternatively, the use of alumina hydrate fine particles causes a problem such as high production cost.

JP-A-10-181190 discloses that a pigment having an average particle diameter of 500 in a cationic polymer-containing liquid is used.
It describes a recording paper having good gloss and high print density by applying a coating solution containing a pigment obtained by pulverizing and dispersing to a thickness of not more than nm on a support.

Japanese Patent Application Laid-Open No. Hei 10-181191 discloses a pigment dispersion obtained by adding a cationic resin to a pigment dispersion having an average particle diameter of 300 nm or less to thicken and agglomerate, and then pulverizing and dispersing the pigment to an average particle diameter of 1 μm or less. Describes a recording sheet obtained by applying a coating solution containing a to a support.

Japanese Patent Application Laid-Open No. 10-71764 discloses that
It describes a recording paper having a layer containing a hydrophilic resin and a secondary agglomerated particle (eg, silica) having an average particle diameter of 10 to 150 nm in which m primary particles are agglomerated.

However, Japanese Patent Application Laid-Open No. 10-181190
The recording paper described in the above publication requires high energy and takes time to be mechanically pulverized and dispersed in the cationic polymer solution because the pigment to be pulverized and dispersed forms an aggregate. Moreover, the occurrence of a remarkable thickening phenomenon in the aggregation process also deteriorates productivity.

[0014] As described in JP-A-10-181191, pigments having a size of 300 nm or less are secondary aggregated particles dispersed by a mechanical method. Not only does this require high energy, thus lowering the productivity, but also leaving coarse agglomerated particles, which tend to cause a decrease in gloss and cracks due to this.

[0015]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to solve the above problems by providing good water resistance, excellent gloss, few cracks, Another object of the present invention is to provide an ink jet recording sheet capable of improving productivity.

[0016]

The above object of the present invention is achieved by the following constitution.

1. Ink jet recording paper obtained by mixing a cationic polymer-containing solution and an inorganic fine particle dispersion dispersed in a state of primary particles, and then applying a coating solution containing a water-soluble polymer on a support. .

2. The mixing of the cationic polymer-containing solution and the inorganic fine particle dispersion dispersed to the state of the primary particles is performed by adding the inorganic fine particle dispersion dispersed to the state of the primary particles to the cationic polymer-containing solution. 2. The ink jet recording paper according to the item 1, wherein

Hereinafter, the present invention will be described in more detail.

As the inorganic fine particles of the present invention, for example, various natural or synthetic inorganic fine particles such as silica, calcium carbonate, titanium oxide, aluminum hydroxide, magnesium carbonate, zinc oxide, barium sulfate, clay and the like can be used. Can be done.

Among them, silica is preferably used for forming an ink receiving layer (hereinafter, also referred to as a void layer) of an ink jet recording paper which requires transparency because of its low refractive index.

As the silica, silica synthesized by a usual wet method, colloidal silica, or fine particle silica synthesized by a gas phase method is preferably used, and as described in the present invention, silica dispersed to primary particles is used. Therefore, colloidal silica or fine particle silica synthesized by a gas phase method is more preferable.Particularly, fine particle silica synthesized by a gas phase method not only has a high porosity, but also has a large porosity when mixed with a cationic polymer. It is particularly preferable because an aggregate is not easily formed.

The average particle size of the inorganic fine particles dispersed to the primary particles of the present invention is preferably from 3 to 100 nm, more preferably from 4 to 50 nm, and most preferably from 4 to 20 nm.

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

The cationic polymer of the present invention can be arbitrarily selected from the known cationic polymers used in conventional ink-jet recording papers. Particularly preferred are those having a weight average molecular weight of 2,000 to 100,000. It is.

The cationic polymer of the present invention is preferably a polymer having a quaternary ammonium base, particularly preferably a homopolymer of a monomer having a quaternary ammonium base, or one or more other copolymerizable monomers. It is a copolymer with a monomer.

Examples of the monomer having a quaternary ammonium base include the following examples.

[0028]

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[0029]

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The monomer copolymerizable with the quaternary ammonium base is a compound having an ethylenically unsaturated group, and examples thereof include the following specific examples.

[0031]

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Particularly when the cationic polymer having a quaternary ammonium base is a copolymer, the proportion of the cationic monomer is preferably at least 10 mol%, more preferably at least 20 mol%, particularly preferably at least 30 mol%. It is.

The monomer having a quaternary ammonium base may be a single monomer or two or more monomers.

Specific examples of the cationic polymer of the present invention are shown below, but the present invention is not limited to these.

[0035]

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[0036]

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[0037]

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[0038]

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The cationic polymer having a quaternary ammonium base is generally high in water solubility because of the quaternary ammonium base, but may be dissolved in water depending on the composition and ratio of the monomer which does not contain a quaternary ammonium base. Although it may not be sufficiently dissolved, any one that can be dissolved by dissolving it in a mixed solvent of a water-miscible organic solvent and water can be used in the present invention.

Here, the water-miscible organic solvent includes alcohols such as methanol, ethanol, isopropanol and n-propanol; glycols such as ethylene glycol, diethylene glycol and glycerin; esters such as ethyl acetate and propyl acetate; It refers to an organic solvent that can be normally dissolved in water by 10% or more, such as ketones such as methyl ethyl ketone and amides such as N, N-dimethylformamide. In this case, the amount of the organic solvent used is preferably equal to or less than the amount of water used.

The cationic polymer of the present invention preferably has a number average molecular weight of 100,000 or less.

Here, the number average molecular weight is a value converted into a polyethylene glycol value obtained by gel permeation chromatography.

When the number average molecular weight exceeds 100,000,
When a solution of the cationic polymer is added to a dispersion containing inorganic fine particles whose surface is anionic, agglomerates are severely generated, and a large number of coarse particles are hard to be formed into a uniform dispersion even after the subsequent dispersion treatment. It is difficult to form a uniform dispersion. When an inkjet recording paper is produced using such a composite fine particle dispersion containing a cationic polymer and inorganic fine particles, it is difficult to obtain high gloss.
A particularly preferred number average molecular weight is 50,000 or less.

The lower limit of the number average molecular weight is usually 2,000 or more from the viewpoint of the water resistance of the dye.

The ratio between the inorganic fine particles and the cationic polymer can vary depending on the type and particle size of the inorganic fine particles, or the type and number average molecular weight of the cationic polymer.

In the present invention, the ratio is preferably from 1: 0.01 to 1: 1 since the surface of the inorganic fine particles needs to be stabilized by replacing the surface with cationic.

In the present invention, the cationic polymer solution and the inorganic fine particle dispersion dispersed to the state of the primary particles are mixed. When the amount of the cationic polymer is small, the anion component of the inorganic fine particles is completely covered. To remain without
The anion part of the inorganic fine particles is ionic-bonded with the cation part of the cationic polymer to easily form coarse particles.

In the present invention, it is preferred that the anionic portion of the inorganic fine particles having an anionic surface is gradually replaced by the cationic portion of the cationic polymer so that the cationic portion is finally increased, and therefore, the dispersion of the inorganic fine particles is preferably used. Care must be taken in the method of adding the cationic polymer, and it is preferable to add a dispersion of inorganic fine particles to the cationic polymer solution.

Conversely, when the cationic polymer solution is added to the dispersion of the inorganic fine particles with stirring, the whole liquid becomes one huge lump in the middle and the stirring becomes almost difficult. The reason for this is that if the cationic polymer is gradually added while the whole liquid is anionic at first, the anion will gradually decrease and the liquid will pass through the neutral region on the way, causing the whole liquid to become anionic. It is presumed that this is likely to result in a huge mass. Even in such a case,
If the cationic polymer is sufficiently present, if the stirring is sufficiently performed over a long period of time, the liquid will eventually gradually be liquefied, but this is not very preferable in terms of production efficiency.

It is preferable that the inorganic fine particle dispersion is gradually added to the cationic polymer solution, so that the whole liquid always maintains cationicity, whereby a dispersion is obtained.

At this time, it is preferable to perform sufficient stirring in the process of adding the inorganic fine particle dispersion, and in some cases, it is preferable to use a disperser during or after the addition in terms of production efficiency.

In the mixed solution thus obtained, when viewed microscopically, a large number of fine lump-like aggregates are present. This is presumably because the cationic polymer is locally insufficient in the inorganic fine particle dispersion at the location where the inorganic fine particle dispersion is added, so that a charge unstable state is formed.

Such fine lump-like aggregates can be reduced by performing a subsequent dispersion treatment. By performing such a dispersion treatment, a dispersion liquid of cation-converted inorganic fine particles having the particle diameter of the original inorganic fine particles in the primary primary particle state can be obtained.

As the dispersion treatment method, various conventionally known dispersion methods such as a high-speed rotation disperser, a medium stirring type disperser (such as a ball mill and a sand mill), an ultrasonic disperser, a colloid mill disperser, a roll mill disperser, and a high-pressure disperser can be used. A disperser can be used, but in the present invention, an ultrasonic disperser or a high-pressure disperser is preferably used from the viewpoint of efficiently dispersing the formed fine particles.

An ultrasonic disperser is usually used for dispersing energy by concentrating energy at a solid-liquid interface by irradiating an ultrasonic wave of 20 to 25 kHz, and it is dispersed very efficiently. Is not very suitable when it is necessary to prepare

On the other hand, the high-pressure dispersing machine is provided with one or two homogenous valves at the outlet of a high-pressure pump having three or five pistons, the gap of which can be adjusted by screw or hydraulic pressure. The flow of the liquid medium sent by the high-pressure pump is restricted by the homogenous valve and pressure is applied. At the moment when the liquid medium passes through the homogenous valve, fine lump material is crushed.

This dispersion treatment method is particularly preferable when a large amount of liquid is produced since a large amount of liquid can be dispersed continuously. The pressure applied to the homogenous valve is usually 50-
The dispersion is 1000 kg / cm ² , and the dispersion can be performed in one pass or can be repeated many times.

The above dispersion processing methods can be used in combination of two or more.

In preparing the above-mentioned dispersion liquid, it can be adjusted by adding various additives.

For example, various nonionic or cationic surfactants (anionic surfactants are not preferred because they form aggregates), defoamers, nonionic hydrophilic polymers (polyvinyl alcohol, polyvinylpyrrolidone) , Polyethylene oxide, polyacrylamide,
Various sugars, gelatin, pullulan, etc.), nonionic or cationic latex dispersion, water-miscible organic solvents (ethyl acetate, methanol, ethanol, isopropanol, n-propanol, acetone, etc.), inorganic salts,
A pH adjuster or the like can be appropriately used as needed.

In particular, a water-miscible organic solvent is preferable because formation of fine lumps when inorganic fine particles and a cationic polymer are mixed is suppressed. Such a water-miscible organic solvent is preferably used in the dispersion in an amount of 0.1 to 20% by weight, particularly preferably 0.5 to 10% by weight.

The pH at which the cationic dispersion is prepared can vary widely depending on the type of inorganic fine particles, the type of cationic polymer, various additives, and the like.
To 8, and particularly preferably 2 to 7.

A water-soluble polymer is then added to the dispersion obtained as described above.

Examples of the water-soluble polymer include gelatin (preferably acid-treated gelatin), polyvinylpyrrolidone (preferably having an average molecular weight of about 200,000 or more), pullulan, polyvinyl alcohol or a derivative thereof, and polyethylene glycol (average molecular weight of 100,000). These are preferred), hydroxyethylcellulose, dextran, dextrin, and water-soluble polyvinyl butyral. These hydrophilic binders may be used alone or in combination of two or more.

Particularly preferred hydrophilic binders are polyvinyl alcohol or cationically modified polyvinyl alcohol.

The polyvinyl alcohol preferably used in the present invention preferably has an average degree of polymerization of from 300 to 4,000, and is particularly preferable because the film having an average molecular weight of 1,000 or more has good brittleness.

The degree of saponification of polyvinyl alcohol is preferably from 70 to 100%, particularly preferably from 80 to 100%. Further, the cation-modified polyvinyl alcohol 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,
Hydroxylethyl dimethyl (3-methacrylamide)
Ammonium chloride, trimethyl- (3-methacrylamidopropyl) ammonium chloride, N-
(1,1-dimethyl-3-dimethylaminopropyl) acrylamide and the like.

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

The degree of polymerization of the cation-modified polyvinyl alcohol is usually 500 to 4000, preferably 1000 to 40.
00 is preferred.

The degree of saponification of the cation-modified polyvinyl alcohol is usually 60 to 100 mol%, preferably 70 to 100 mol%.
~ 99 mol%.

Particularly preferred in the present invention is a case where fine-particle silica is used as primary particles and polyvinyl alcohol or modified polyvinyl alcohol is used as a hydrophilic binder. In this case, the silanol group on the surface of the fine particle silica and the hydroxyl group of vinyl alcohol form a weak hydrogen bond, so that a soft agglomerate is formed and the porosity tends to increase.

The ratio of the water-soluble polymer to the inorganic fine particles is usually from 1:10 to 1: 3, particularly preferably 1: 1.
8 to 1: 5.

The method of adding the water-soluble polymer to the dispersion is preferably to add the aqueous solution of the water-soluble polymer to the dispersion while stirring. The temperature in this case is usually 30 to 5
It is better to be in the range of 0 ° C. If the temperature is lower than 30 ° C., the viscosity of the coating liquid becomes too high, the stirring efficiency is reduced, and aggregates and lumps are easily formed locally. On the other hand, if the temperature exceeds 50 ° C., the coating liquid tends to deteriorate such as thickening while the coating liquid is stagnant.

When a water-soluble polymer is added, a small amount of a low-molecular-weight water-soluble polymer is added in advance, and then when the water-soluble polymer of the present invention is added to this solution, aggregation and thickening are unlikely to occur and stable. Coating and film surface are obtained, and cracks and the like are hardly generated.

The weight-average molecular weight of the low-molecular-weight water-soluble polymer is usually from 2,000 to 50,000, especially
Those having 0 to 40,000 are preferred. The ratio of the low-molecular weight water-soluble polymer to the water-soluble polymer of the present invention is usually in the range of 0.001 to 0.2, and particularly 0.002 to 0.2.
0.1 is preferred.

In the present invention, the low molecular weight water-soluble polymer is particularly preferably polyvinyl alcohol having a degree of polymerization of 300 to 600.

The coating solution thus obtained can be added with various additives as needed. These additives can also be added before adding the water-soluble polymer.

It is preferable that the above-mentioned coating solution is thereafter applied onto a support without mechanical dispersion.

When such a coating liquid is mechanically dispersed, the obtained coating liquid is homogenized, but tends to crack.

Here, the mechanical dispersion refers to stirring by the above-described various dispersers, and is performed by ordinary stirring (usually 1000 rpm).
pm) does not cause such a problem.

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

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

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, bisvinylsulfonyl methyl ether, etc.), boric acid, salts thereof, borax, aluminum alum and the like.

When polyvinyl alcohol or cationically modified polyvinyl alcohol is used as the water-soluble polymer, it is preferable to use a hardener selected from boric acid, a salt thereof, or an epoxy hardener.

The most preferred is a hardening agent selected from boric acid or a salt thereof.

The boric acid or a salt thereof refers to an oxyacid having a boron atom as a central atom and a salt thereof, and specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, octanoic acid or a salt thereof. Salts.

The amount of the hardener used varies depending on the type of the water-soluble polymer, the type of the hardener, the type of the inorganic fine particles, the ratio to the water-soluble polymer, and the like. Is 10 to 300 m
g.

The above-mentioned hardener is added to the coating liquid for forming the void layer and / or the coating liquid for forming other layers adjacent to the void layer when the coating liquid for forming the void layer is applied. Alternatively, a coating solution for forming the void layer is applied on a support on which a coating solution containing a hardener is applied in advance. Further, the hardening agent can be supplied to the void layer by, for example, coating and drying a hardener-free coating solution for forming the void layer and then overcoating the hardener solution. Preferably, from the viewpoint of production efficiency, a hardening agent is added to the coating solution for forming the void layer or the coating solution for forming a layer adjacent thereto, and the hardener is simultaneously formed with the void layer. Preferably, it is supplied.

In a particularly preferred embodiment in which the void layer is formed of ultrafine silica and polyvinyl alcohol synthesized by a gas phase method, a hardener is added in advance to the coating solution for forming the void layer. When a predetermined time (preferably 10 minutes or more, particularly preferably 30 minutes or more) has elapsed and then applied and dried on the support, a higher porosity can be achieved without deteriorating the brittleness of the film.

The above-mentioned hardener can be added as an additive when preparing the cationic composite fine particle dispersion of the present invention in advance.

Various additives other than those described above can be added to the void layer of the ink jet recording paper of the present invention and other layers provided as necessary.

For example, polystyrene, polyacrylic esters, polymethacrylic esters, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or copolymers thereof,
Organic latex fine particles such as urea resin and melamine resin, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate and silicone oil, various surfactants such as cations and nonions, and JP-A-57-7419.
No. 3, No. 57-87988 and No. 62-26.
UV absorber described in JP-A-1476, JP-A-57-7
Nos. 4192 and 57-87989, 60-72
No. 785, No. 61-146591, JP-A No. 1
Discoloration inhibitors described in JP-A-95091 and JP-A-3-13376, JP-A-59-42993, JP-A-59-52689, and JP-A-62-280069.
Gazette, JP-A-61-242871 and Japanese Patent Laid-Open No.
No. 219266, a fluorescent whitening agent, a pH adjusting agent such as sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, an antifoaming agent, a preservative,
Various known additives such as a thickener, an antistatic agent, and a matting agent can be contained.

The void volume of the ink jet recording paper of the present invention is usually 20 to 40 ml / m ² , and the void ratio of the void layer is usually 0.5 to 0.8.

The above-mentioned void layer may be composed of two or more layers. In this case, the configurations of the void layers may be the same or different.

As the support of the ink jet recording paper of the present invention, a paper support, a plastic support (transparent support), a composite support, etc., which are conventionally known as ink jet recording papers, can be used as appropriate. In order to obtain a good image, it is preferable to use a hydrophobic support that does not penetrate the ink liquid into the support.

The transparent support is made of, for example, polyester resin, diacetate resin, triacetate resin, acrylic resin, polycarbonate resin, polyvinyl chloride resin, polyimide resin, cellophane, celluloid and the like. Film and the like.
Those having the property of resisting radiant heat when used as HP are preferable, and polyethylene terephthalate is particularly preferable. The thickness of such a transparent support is 10 to 2
00 μm is preferred. It is possible to provide a known undercoat layer on the ink receiving layer side and the backing layer side of the transparent support,
It is preferable from the viewpoint of the adhesiveness between the ink receiving layer or the back layer and the support.

Examples of the support used when it is not necessary to be transparent include resin-coated paper (so-called RC paper) having a polyolefin resin-coated layer obtained by adding a white pigment or the like to at least one of base paper, polyethylene terephthalate A so-called white pet obtained by adding a white pigment to the ink is preferred.

For the purpose of increasing the adhesive strength between the support and the void layer, it is preferable to subject the support to a corona discharge treatment, a subbing treatment or the like prior to the application of the void layer. Furthermore, the recording paper of the present invention does not necessarily need to be colorless, and may be a colored recording paper.

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

The base paper used for the paper support is made from wood pulp as a main raw material, and if necessary, in addition to wood pulp, using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester. As wood pulp, LBKP, LBSP, NBKP, NBSP, LD
Any of P, NDP, LUKP, and NUKP can be used, but LBKP, NBSP, and LBS containing a large amount of short fibers
It is preferable to use more P, NDP and LDP.
However, the ratio of LBSP and / or LDP is 10% by weight.
At least 70% by weight is preferred.

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

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

The freeness of the pulp used for papermaking is preferably 200 to 500 cc according to the specification of CSF, and the fiber length after beating is defined as the weight percentage of the remaining 24 mesh specified in JIS-P-8207 and 42 mesh. The sum with the remaining weight% is 3
0-70% is preferred. The weight percentage of the remaining 4 mesh
Is preferably 20% by weight or less.

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

The base paper may be calendered at the papermaking stage or after the papermaking to provide high smoothness. The base paper density is generally 0.7 to 1.2 g / m ² (JIS-P-8118). Further, the rigidity of the base paper is preferably from 20 to 200 g under the conditions specified in JIS-P-8143.

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

The pH of the base paper is preferably 5 to 9 as measured by the hot water extraction method specified in JIS-P-8113. The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene ( LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene, etc. can also be used partially.

In particular, the polyethylene layer on the ink receiving layer side is preferably a layer obtained by adding rutile or anatase type titanium oxide to polyethylene to improve opacity and whiteness as widely used in photographic printing paper. The content of titanium oxide is usually 3 to 20% by weight based on polyethylene,
Preferably it is 4 to 13% by weight.

The polyethylene-coated paper may be used as a glossy paper, or may be subjected to a so-called embossing process when the polyethylene is melt-extruded onto the base paper surface to carry out a coating process. Those having a surface can also be used in the present invention.

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

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

1. Tensile strength: JIS-P-8113
2-30 kg in the vertical direction and 1 in the horizontal direction with the strength specified by
1. It is preferably 20 kg. Tear strength: 10 to 200 g in the vertical direction and 20 to 200 g in the horizontal direction according to the method specified in JIS-P-8116.
Is preferred. ^3. Compression elastic modulus ≧ 10 ³ kgf / cm ² 4. Surface Beck smoothness: 20 seconds or more is preferable as a glossy surface under the conditions specified in JIS-P-8119, but may be less than this for so-called molded products. Surface roughness: Surface roughness specified in JIS-B-0601, maximum height 10 μm per reference length 2.5 mm
It is preferably the following. Opacity: preferably 80% or more, particularly 85 to 9 when measured by the method specified in JIS-P-8138.
8% is preferred Whiteness: L ^* defined by JIS-Z-8729,
a ^* and b ^* are L ^* = 80 to 95, a ^* = − 3 to +5, b ^*
= -6 to +2 Surface glossiness: 6 specified in JIS-Z-8741
8. It is preferable that the 0 degree specular gloss is 10 to 95%. Clark stiffness: Clark stiffness in the conveying direction of the recording sheet is 50~300cm ^2/100 support is preferably 10. Moisture content of middle paper: usually 2 to 10% by weight, preferably 2 to 6% by weight based on the middle paper Various kinds of hydrophilic layers appropriately provided as necessary such as a void layer and an undercoat layer of the recording paper of the present invention. Can be appropriately selected from known methods. A preferred method is obtained by applying a coating solution constituting each layer on a support and drying it. In this case, two or more layers can be coated simultaneously, and in particular, simultaneous coating in which all the hydrophilic binder layers need only be applied once is preferable.

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

When recording an image using the inkjet recording paper of the present invention, a recording method using an aqueous ink is preferably used.

Aqueous inks include the following colorants and liquid media:
This is a recording liquid having other additives. As the colorant, a water-soluble dye or a water-dispersible pigment such as a direct dye, an acid dye, a basic dye, a reactive dye, or a food colorant known by inkjet can be used.

Examples of the solvent for the aqueous ink include water and various water-soluble organic solvents, for example, alcohols such as methyl alcohol, isopropyl alcohol, n-butyl alcohol, tert-butyl alcohol and isobutyl alcohol; dimethylformamide, dimethylacetamide and the like. Amides; 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
Polyhydric alcohols such as hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, glycerin and triethanolamine; polyhydric alcohols such as ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether and triethylene glycol monobutyl ether; And lower alkyl ethers.

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

As other additives for the aqueous ink, for example, a pH adjuster, a sequestering agent, a fungicide, a viscosity adjuster,
Examples include surface tension adjusters, wetting agents, surfactants, and rust inhibitors.

The aqueous ink liquid is usually used at 20 ° C. for 25 to 60 d in order to improve the wettability on the recording paper.
It preferably has a surface tension in the range of yn / cm, preferably 30 to 50 dyn / cm.

[0121]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, “%” indicates absolute dry weight% unless otherwise specified.

Example 1 "Preparation of Titanium Oxide Dispersion-1" The average particle size was about 0.25.
20 kg of titanium oxide (μm) (W-10, manufactured by Ishihara Sangyo Co., Ltd.) and 150 g of sodium tripolyphosphate having a pH of 7.5,
Polyvinyl alcohol (Kuraray Co., Ltd .: PVA23
5) 500 g, 150 of cationic polymer (p-9)
g and Sannobuco defoamer SN381 to 10
g, and dispersed in a high-pressure homogenizer (manufactured by Sanwa Kogyo Co., Ltd.).
To obtain a uniform titanium oxide dispersion liquid-1.

[Preparation of Silica Dispersion-1] 125 kg of fumed silica (A300 manufactured by Nippon Aerosil Co., Ltd.) having an average primary particle size of about 0.007 μm was jetted from Mitamura Riken Kogyo Co., Ltd. Using a stream inductor mixer TDS, the mixture was suction-dispersed at room temperature in 620 L of pure water adjusted to pH = 2.5 with nitric acid, and the whole amount was finished to 694 L with pure water. The dispersion was diluted and an electron micrograph of the particles was taken.
It was confirmed that the particles had a size of 1 μm or less and were dispersed to primary particles.

"Preparation of Silica Dispersion-2" 1.29 kg of cationic polymer (P-9) and 4.2 parts of ethanol
L, solution containing 1.5 L of n-propanol (pH =
2.3) 69.4 L of silica dispersion-1 was added to 18 L with stirring, and then 260 g of boric acid and borax 2 were added.
7.0 L of an aqueous solution containing 30 g was added, and 1 g of the antifoaming agent SN381 was added.

This mixture was dispersed twice at a pressure of 250 kg / cm ^{2 with} a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd.
The total amount was adjusted to 97 L with pure water to prepare an almost clear silica dispersion liquid-2.

"Preparation of Fluorescent Whitening Agent Dispersion-1" Oil-soluble fluorescent whitening agent UVITEX-OB manufactured by Ciba-Geigy Co., Ltd.
400 g was dissolved by heating in 9000 g of diisodecyl phthalate and 12 L of ethyl acetate, and this was added to 3500 g of acid-treated gelatin, 50% solution of cationic polymer (P-1) and saponin. The mixture was emulsified and dispersed three times with a high-pressure homogenizer manufactured by Wako Kogyo Co., Ltd. at a pressure of 250 kg / cm ² , and ethyl acetate was removed under reduced pressure.

"Preparation of Matting Agent Dispersion-1" Methacrylic acid ester-based matting agent MX-15 manufactured by Soken Kagaku Co., Ltd.
156 g of 00H was added to 7 L of pure water containing 3 g of the PVA235, and the mixture was dispersed with a high-speed homogenizer for 30 minutes to finish the whole amount to 7.8 L.

"Preparation of Coating Solution" Coating solutions for the first, second and third layers were prepared in the following procedure.

Coating solution for first layer: 60 of silica dispersion-2
The following additives were sequentially mixed with 0 ml while stirring at 40 ° C.

10% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA203): 0.6 ml 5% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235): 260 ml Fluorescent brightener dispersion liquid-1: 25 ml oxidation Titanium Dispersion-1: 33 ml, manufactured by Daiichi Kogyo Co., Ltd .: Latex Emulsion AE-803: 18 ml.

Coating solution for second layer: 65 of silica dispersion liquid-2
The following additives were sequentially mixed with 0 ml while stirring at 40 ° C.

10% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA203): 0.6 ml 5% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235): 270 ml Fluorescent brightener dispersion liquid-1: 35 ml pure Make up to 1000 ml with water.

Coating solution for third layer: 65 of silica dispersion-2
The following additives were sequentially mixed with 0 ml while stirring at 40 ° C.

10% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA203): 0.6 ml 5% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235): 270 ml Silicon dispersion (Toray Dow Corning Silicone Co., Ltd.) (BY-22-839): 15 ml Saponin 50% aqueous solution: 4 ml Matting agent dispersion liquid-1: 10 ml Make up to 1000 ml with pure water.

The coating solution obtained as described above was filtered with the following filter.

First layer and second layer: two steps with TCP10 manufactured by Toyo Filter Paper Co., Ltd. third layer: two steps with TCP30 manufactured by Toyo Filter Paper Co., Ltd. Then, a paper support coated on both sides with polyethylene (thickness of 220 μm and ink absorption) The first layer (50 μm) and the second layer (100 μm) contained 13% by weight of anatase type titanium oxide based on the polyethylene in the layer surface polyethylene.
m) and the third layer (50 μm). The figures in parentheses indicate the respective wet film thicknesses, and the first layer to
The third layer was applied simultaneously.

Each coating solution was applied at 40 ° C. with a three-layer slide hopper, and immediately after the coating, the solution was cooled in a cooling zone maintained at 0 ° C. for 20 seconds, and then blown with a wind at 20 to 30 ° C. for 60 seconds. , 45 ° C for 60 seconds, 50 ° C for 6 seconds
The recording paper-1 was obtained by drying sequentially for 0 second.

[0138] Recording paper-1 was prepared in the same manner as recording paper-1, except that recording paper-2 was changed as follows.

Recording Paper-2: In the preparation of "Silica Dispersion-2", a solution containing a cationic polymer was added to the silica dispersion, and then a solution containing boric acid and borax and an antifoaming agent were added. Recording paper-1 except for changing the order of addition
It was produced in the same manner as described above.

In this case, the stirring time before dispersion was extended to 2 hours, compared to 5 minutes in the case of recording paper-1 because the viscosity of the liquid was so thickened during mixing.

Recording paper-3: Recording paper-2 except that the number of dispersion was 3 in the preparation of "silica dispersion liquid-2"
It was produced in the same manner as described above.

Recording paper-4: Recording paper-2 except that the number of dispersion was 4 in the preparation of "silica dispersion liquid-2"
It was produced in the same manner as described above.

Recording Paper-5: The following dispersion was prepared as silica dispersion-1A.

Using silica obtained by a wet method and having an average particle size of about 3 μm, 30 g
After pre-dispersing for 2 minutes, using the high-pressure homogenizer used above, dispersing twice at 500 kg / cm ² and silica dispersion liquid 1A comprising a secondary aggregate having an average particle size of about 120 nm
(Concentration: 10%).

Using this, a silica dispersion-2A containing a cationic polymer was prepared in the same manner as “silica dispersion-2” prepared for recording paper-1. This dispersion was a cloudy dispersion as compared with the silica dispersion-2.

Thereafter, it was produced in the same manner as for recording paper-1. However, since the concentration of the silica dispersion was insufficient and the coating solution was diluted (about 10%), the wet film thickness was adjusted so that the coating amount of the solid content was the same as that of the recording paper-1. Application was performed.

Recording Paper-6: A recording paper-5 was prepared in the same manner as recording paper-5, except that the number of times of dispersion with a high-pressure homogenizer was three in preparation of silica dispersion liquid-2A.

Recording paper-7: Recording paper-5 except that the number of times of dispersion by a high-pressure homogenizer was four in preparation of silica dispersion liquid-2A in preparation of recording paper-5.
It was produced in the same manner as described above.

Recording Paper-8: A recording paper-5 was prepared in the same manner as the recording paper-5, except that the number of dispersions by the high-pressure homogenizer was changed to 5 in the preparation of the silica dispersion liquid-2A.

Recording Paper-9: A recording paper-5 was prepared in the same manner as the recording paper-5, except that the number of times of dispersion by the high-pressure homogenizer was changed to six.

Recording Paper-10: In the preparation of “Silica Dispersion-1A” of Recording Paper-5, the dispersion time of a sand grinder was set to 2 hours, and the number of dispersions by a high-pressure homogenizer was changed from 2 to 5 times to obtain an average particle diameter A silica dispersion liquid 1B of about 50 nm secondary aggregated particles was prepared. Using this silica dispersion-1B, a silica dispersion-2B was prepared in the same manner as for recording paper-5. This dispersion is a silica dispersion-2.
Although the cloudiness was lower than that of A, the silica dispersion-
The cloudiness was higher than that of No. 2. Then, a recording sheet was prepared in the same manner as in recording sheet-5.

Recording Paper-11: A silica dispersion liquid-2B was prepared in the same manner as the recording paper-10 except that the dispersion was performed with a high-pressure homogenizer three times.

Recording Paper-12: A silica dispersion liquid-2B was prepared in the same manner as the recording paper-10, except that the dispersion was performed with a high-pressure homogenizer four times.

Recording Paper-13: Prepared in the same manner as Recording Paper-10, except that the dispersion of silica dispersion liquid 2B was performed by changing the number of dispersions of the high-pressure homogenizer to six.

The following items were evaluated for the recording papers 1 to 13.

(1) Glossiness: A glossiness measured at 75 degrees using a variable angle photometer (VGS-1001DP) manufactured by Nippon Denshoku Industries Co., Ltd. The higher the value, the better the glossiness.

(2) Cracking: The number of cracking points per 0.3 m ^{2 of the} coated surface is visually counted. If the number of cracking points is usually 10 or less, it is considered that there is no practical problem.

(3) Maximum density: Solid printing of magenta was performed using an ink jet printer PM750C manufactured by Seiko Epson Corporation, and the maximum reflection density was measured.

Table 1 shows the obtained results.

[0160]

[Table 1]

Silica Dispersion-1: Gas-phase method silica dispersion Liquid silica obtained by dispersing wet-process silica in a sand grinder (30 minutes) + high-pressure homogenizer (twice) and wet-process silica in a sand-grinder (2 hours) + Liquid obtained by dispersing with a high-pressure homogenizer (5 times) Silica dispersion-2: Addition of silica dispersion-1 to cationic polymer solution Addition of cation dispersion to silica dispersion-1 Each value is the number of times of dispersion of high-pressure homogenizer. Is shown.

From the results shown in Table 1, it was found that recording paper-1 was produced in a short time (5 ') by adding a fumed silica dispersion to a cationic polymer-containing solution, thereby reducing the formation of coarse aggregates when mixing the two. A relatively uniform liquid was formed, and a good dispersion was obtained by two high-pressure dispersions.

The recording paper obtained by using this dispersion had excellent gloss, a small number of cracks, and a good film surface. It can also be seen that the maximum concentration is high.

On the other hand, recording paper-2 in which the addition order of the fumed silica dispersion liquid-1 and the cationic polymer was changed.
In Nos. 4 to 4, a lot of lumps are generated in the process of preparing the silica dispersion liquid 2, and a little time is required for dispersion. However, if the number of dispersions of the high-pressure homogenizer is increased, the film surface is almost equivalent to the recording paper 1. And the maximum concentration can be obtained.

On the other hand, the recording papers -5 to 13 obtained by mechanically pulverizing and dispersing wet-process silica in advance and mixing it with the cationic polymer while keeping the secondary aggregated particles all have a decrease in glossiness. It can be seen that there is an increase in cracks and a decrease in the maximum density.

By increasing the number of dispersions of the high-pressure homogenizer after mixing the cationic polymer and the silica dispersion, the characteristics are improved little by little, but they do not reach recording papers 1-4.

Example 2 Each of the coating liquids for producing the recording papers 1 and 4 used in Example 1 was mixed with the coating liquids and then dispersed again with a high-pressure homogenizer under the conditions of 100 kg / cm ^2. Then, recording paper-1A and 4A were produced in the same manner as recording paper-1. Evaluation was performed in the same manner as in Example 1, and the obtained results are shown in Table 2.

[0168]

[Table 2]

From the results shown in Table 2, the glossiness and the maximum density were slightly increased by redispersing the mixed coating solution with a high-pressure homogenizer, but the cracks were slightly increased.

[0170]

As demonstrated in the examples, the ink jet recording paper according to the present invention has excellent water resistance, excellent gloss, little cracks, and can improve productivity, and has excellent effects.

Claims (2)

[Claims] 1. A solution obtained by mixing a cationic polymer-containing solution and an inorganic fine particle dispersion dispersed in a state of primary particles, and then applying a coating solution containing a water-soluble polymer to a support. Inkjet recording paper. 2. A method according to claim 1, wherein the cationic polymer-containing solution and the inorganic fine particle dispersion dispersed in the state of the primary particles are mixed, and the cationic polymer-containing solution is mixed with the inorganic fine particle dispersion dispersed in the state of the primary particles. The ink jet recording sheet according to claim 1, wherein the recording is performed.