JP2001080207A - Manufacture of ink jet recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously improve both a craze and a folding crack by in-line adding a crosslinker immediately before coating in the case of coating an ink receiving layer. SOLUTION: In the case of in-line adding a boric acid or a borate used as a crosslinker to be added to an ink receiving layer having a binder to maintain characteristics as a film immediately before coating, it is good to in-line add an overall amount of the acid in view of improving both a craze and a folding crack. As a suitable adding amount of the acid, about 8 to 30 wt.% to a polyvinyl alcohol contained as a binder is good, and a concentration of the acid of a solution to be in-line added is set to about 1 to 10 wt.%. A coating liquid of a storage oven 1 is dropped through a pipe 1 by utilizing a head difference, while a solution containing the crosslinker as an in-line adding liquid of a storage oven 3 is dropped through a pipe 4. Then, the liquid and the crosslinker are controlled to predetermined flow rates by flowmeters 5, 6, and then mixed by an in-line mixer 7 to a completer coating liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing an ink jet recording material.

[0002]

2. Description of the Related Art As a recording material used in an ink jet recording system, a pigment such as amorphous silica is coated on a support called a normal paper or an ink jet recording paper by a porous material comprising a water-soluble binder such as polyvinyl alcohol. There is known a recording material provided with an ink absorbing layer.

[0003] For example, Japanese Patent Application Laid-Open No. 55-51583,
Nos. 6-157, 57-107879, 57-10
No. 7880, No. 59-230787, No. 62-160
No. 277, No. 62-184879, No. 62-1833
As disclosed in JP-A-82 and JP-A-64-11877, a recording material obtained by applying a silicon-containing pigment such as silica to a paper support together with an aqueous binder has been proposed.

[0004] Also, Japanese Patent Publication No. 3-56552,
No. 188287, No. 10-81064, No. 10
No.-119423, No. 10-175365, No. 10
-203006, 10-217601, 11
No. -20300, No. 11-20306, No. 11-
Japanese Patent Publication No. 34481 and the like disclose a technique for improving gloss and ink absorbency by using synthetic silica fine particles obtained by a gas phase method (hereinafter, referred to as gas phase silica).

[0005] Forming an ink receiving layer having a void layer formed of inorganic fine particles on a support as described above is one of effective means for increasing the ink absorbency of a recording material. The amount of the hydrophilic binder used is limited so that the hydrophilic binder used in combination with the fine particles does not block the void layer and reduce the ink absorbency.

[0006] As described above, the ink receiving layer film coated and dried with a minimum necessary amount of a hydrophilic binder with respect to the inorganic fine particles in order to efficiently increase the void volume has a low film strength. Later, fine cracks occur on the film surface, and the image quality remarkably deteriorates, such as a decrease in gloss or blurring of the image. In particular, when an ink receiving layer containing inorganic fine particles having an average particle diameter of 0.1 μm or less is provided, cracks are likely to occur. It is known to use a hydrophilic binder and its crosslinking agent in combination in order to prevent this cracking.

[0007] As the crosslinking agent, for example, epoxy compounds, aldehyde compounds, active halogen compounds, boric acid and its salts, borax, aluminum alum and the like are known.

However, when a sufficient amount of the crosslinking agent is used to prevent the occurrence of cracks, there arises an inconvenience that the phenomenon of breakage newly occurs. Breakage is a phenomenon in which, when handling a sheet-like recording material, when the recording material is bent, a crack is generated on the surface of the ink receiving layer. In particular, posters and storefronts that have attracted attention in recent years
In applications for printing with a commercial inkjet plotter such as an OP, a large problem is likely to occur due to handling of a large-sized sheet, which is a serious problem.

In particular, silica synthesized by a gas phase method is an ultrafine particle having an average primary particle diameter of several tens of nanometers or less, so that high gloss and high ink absorbency can be obtained. Therefore, there is a problem that it is easy to cause breakage during handling, and there is a demand for a technique for improving both of them.

[0010]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing an ink jet recording material which simultaneously improves both cracks and breaks.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink-jet recording material comprising an ink receiving layer mainly containing inorganic fine particles, and a binder and a crosslinking agent for the binder coated on a support. Wherein the crosslinking agent is added in-line immediately before the application of the ink-receiving layer when the ink-receiving layer is applied.

According to the present invention, it has been found that by adding the crosslinking agent in-line immediately before coating, even if the amount of the crosslinking agent added is reduced, no cracking occurs and the breaking is prevented. This is presumably because the in-line addition of the cross-linking agent caused the cross-linking agent to efficiently act on the binder against surface cracks, and as a result, the weight was reduced.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, the coating liquid for the ink receiving layer (hereinafter, referred to as a coating liquid) contains at least inorganic fine particles, a binder, and a crosslinking agent thereof. In addition, it contains a cationic compound, a surfactant, an organic solvent and the like. The amount of the inorganic fine particles in the coating solution is at least 50% by weight, preferably 60% by weight, based on the total solid content.

The coating liquid is usually prepared by dispersing inorganic fine particles in water using a high-pressure homogenizer, a high-speed homogenizer, a ball mill or the like, and mixing the dispersion with a hydrophilic binder, a crosslinking agent, a surfactant and the like. In order to increase the production efficiency, it is preferable to prepare a large amount of the coating solution at one time and apply it continuously. Therefore, the amount of the coating liquid produced at one time is applied to the support over a long time. For example 5 hours, even 1
It may exceed 0 hours. Until the application is completed after the preparation of the application liquid, the application liquid is kept at a temperature of about 30 to 45 ° C. and aged.

The coating liquid is usually manufactured in a unit of several hundred liters to several thousand liters per batch, temporarily stored in a storage tank (tank), and using a pump or a head difference (height difference) from the storage tank. The liquid is supplied to a coating device through a liquid feed pipe such as a pipe, and is coated on a support. As described above, conventionally, all components of the ink receiving layer were added during the production of the coating liquid, and were supplied to the coating apparatus in the form of a complete coating liquid.
In the present invention, a coating solution is produced without adding a part or all of the crosslinking agent, and the crosslinking agent is added to and mixed with the coating solution immediately before the application of the coating solution. Specifically, a part or all of the cross-linking agent is added to and mixed with the coating liquid through a path in which the coating liquid is sent from the storage tank to the coating apparatus. This method is also called in-line addition, and a mixing device for that is also commercially available as an in-line mixer or a static mixer. For example, Kenics (USA)
Mixer, Sulger (Switzerland)
Static Mixing Element SMV type manufactured by KoRitsu Kogyo Co., Ltd., Shimazaki Pipe Mixer manufactured by Toray Industries, Inc., and Hi-Mixer manufactured by Toray Industries, Inc. Further, as the in-line dynamic mixer, those described in Japanese Patent Application No. 11-80655 can be used.

The step of adding immediately before coating according to the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic diagram of the manufacturing process. The coating liquid stored in the storage tank 1 is lowered through the pipe 2 using a head difference (a high-viscosity coating liquid can be used with a pump (not shown)). on the other hand,
A solution containing a cross-linking agent is stored in the storage tank 3 as an in-line addition liquid, and is similarly lowered through the pipe 4 using the head difference. The lowered coating solution and the crosslinking agent are controlled to predetermined flow rates by flow meters 5 and 6, respectively, and then mixed by an in-line mixer 7 to form a complete coating solution, which is sent to a coating device 8 and supported. Applied to

Next, the structure of the ink receiving layer will be described. The ink receiving layer of the present invention mainly contains inorganic fine particles. As inorganic fine particles, calcium carbonate,
Magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, hydrotalcite, aluminum silicate, diatomaceous earth,
Examples include calcium silicate, synthetic silica, colloidal silica, alumina, pseudoboehmite and the like. Among these, synthetic silica is preferable, and fumed silica is particularly preferably used. Since the fumed silica is fine particles, fine cracks are easily generated on the coated surface, and breakage is easily generated during handling. Therefore, the present invention is suitable for a production method using fumed silica for the ink receiving layer.

Synthetic silica includes those obtained by a wet method and those obtained by a gas phase method. Usually, silica fine particles often refer to wet process silica. As wet silica, silica sol obtained by metathesis of sodium silicate with an acid or the like through an ion exchange resin layer, or colloidal silica obtained by heating and aging this silica sol, gelling silica sol, and changing the production conditions Silicic acid such as silica gel in which primary particles of several microns to 10 microns have become siloxane-bonded three-dimensional secondary particles, and those obtained by heating and producing silica sol, sodium silicate, sodium aluminate, etc. And the like.

In the present invention, the fumed silica preferably used is also called a dry method as opposed to a wet method, and is generally produced by a flame hydrolysis method. Specifically, a method of making silicon tetrachloride by burning it with hydrogen and oxygen is generally known, but instead of silicon tetrachloride, silanes such as methyltrichlorosilane and trichlorosilane may be used alone or in a silicon tetrachloride. And can be used in a mixed state. The fumed silica is commercially available as Aerosil from Nippon Aerosil Co., Ltd. and QS type from Tokuyama Co., Ltd. and can be obtained.

The average particle size of the primary particles of the fumed silica used in the present invention is preferably 30 nm or less. In order to obtain higher gloss, the average particle size is 3 to 10 nm and the specific surface area by the BET method is 250 m ² / g. Or more (preferably 250 to 50
(0 m ² / g). The BET method referred to in the present invention is one of the methods for measuring the surface area of a powder by a gas phase adsorption method, and is a method for determining the total surface area of 1 g of a sample, that is, the specific surface area, from an adsorption isotherm. Usually, nitrogen gas is often used as the adsorbed gas, and the method of measuring the amount of adsorption from the change in pressure or volume of the gas to be adsorbed is most often used. The most prominent for expressing isotherms for multimolecular adsorption is the Brunauer, Emmett, Teller equation, BE
It is called T type and is widely used for determining the surface area. BET
The surface area is obtained by calculating the amount of adsorption based on the formula and multiplying the area occupied by one adsorbed molecule on the surface.

The feature of the above-mentioned fumed silica is that the primary particles are present in a state of being secondary aggregated by being connected in a network structure or a chain shape, whereby high ink absorbability is obtained. The state of the secondary aggregation is 50 to 500 n.
m, so that high ink absorbency can be obtained without reducing gloss.

In the present invention, the amount of the inorganic fine particles contained in the ink receiving layer is preferably 8 g / m ² or more.
A range of 30 g / m ² is more preferred.

In the present invention, the ink receiving layer containing the inorganic fine particles has a binder for maintaining the properties as a film. As the binder, various known hydrophilic binders can be used. For example, gelatin and its derivatives, polyvinylpyrrolidone, pullulan, polyvinyl alcohol and its derivatives, polyethylene glycol, carboxymethylcellulose, hydroxyethylcellulose, dextran, dextrin, polyacrylic acid and its salts, agar, carrageenan, xanthen gum, locust bean gum, and alginic acid Gum arabic, JP-A-7-197826, JP-A-7-9957
And polyalkylene oxide copolymers described in JP-A-62-245260, water-soluble polyvinyl butyral, and homo- or copolymers of a vinyl monomer having a carboxy group or a sulfonic acid group described in JP-A-62-245260. Can be.

Among the above-mentioned hydrophilic binders, a hydrophilic binder which has a high transparency and a higher ink permeability can be preferably used. As the hydrophilic binder, polyvinyl alcohol and cation-modified polyvinyl alcohol are preferably used.

Particularly preferred among polyvinyl alcohols are those partially or completely saponified with a degree of saponification of 80 or more. Polyvinyl alcohol having an average degree of polymerization of 500 to 5000 is preferred.

As the cation-modified polyvinyl alcohol, for example, as described in JP-A No. 61-10483, a primary to primary amino group or a quaternary ammonium group is added to the main chain or side chain of polyvinyl alcohol. It is a polyvinyl alcohol contained therein.

It is preferable to use the above-mentioned hydrophilic binder in a small ratio with respect to the inorganic fine particles from the viewpoint of ink absorbability, but cracks and breaks are liable to occur.
The most important feature of the present invention is that cracks and breaks can be prevented even when the amount of the hydrophilic binder is used in a small ratio of 30% by weight or less with respect to the inorganic fine particles. Therefore, in the present invention, it is preferable to use the hydrophilic binder in an amount of 30% by weight or less, preferably 10 to 27% by weight, based on the inorganic fine particles.

In the present invention, a crosslinking agent (hardening agent) is used together with the hydrophilic binder. Specific examples of the cross-linking agent include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedione, and bis (2-chloroethyl urea) -2.
-Hydroxy-4,6-dichloro-1,3,5 triazine, a compound having a reactive halogen as described in U.S. Pat. No. 3,288,775, divinyl sulfone, and a compound described in U.S. Pat. No. 3,635,718. A compound having a reactive olefin, an N-methylol compound as described in U.S. Pat. No. 2,732,316, and a U.S. Pat.
Isocyanates as described in U.S. Pat.
Aziridine compounds described in US Pat. Nos. 017,280 and 2,983,611; carbodiimide compounds described in US Pat. No. 3,100,704;
No. 091,537, halogen carboxaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane, and inorganic crosslinking agents such as chrome alum, zirconium sulfate, boric acid and borate. Alternatively, two or more kinds can be used in combination.

The amount of the crosslinking agent to be added is appropriately determined depending on the type of the crosslinking agent, the type and the amount of the hydrophilic binder, and the type and the amount of the inorganic fine particles. The present invention, from the viewpoint of improving cracks and breaks,
The optimum amount of crosslinking agent can be determined empirically. Normal,
It is used in the range of 0.1 to 40% by weight based on the hydrophilic binder.

In a preferred embodiment of the present invention, 10 to 30 g / m ^{2 of} fumed silica as inorganic fine particles, 10 to 30% by weight of polyvinyl alcohol as a binder with respect to fumed silica, and boric acid or borate as a crosslinking agent Is used.

In the present invention, boric acid or a borate is added in-line immediately before coating. The boric acid added in-line may be a part or the whole of the total boric acid amount. In the present invention, from the viewpoint of improving cracks and breaks, an appropriate ratio of the amount of in-line addition can be determined empirically. In the present invention, it is preferable to add the entire amount of boric acid in-line. The preferred amount of boric acid varies depending on the particle size and amount of fumed silica and the amount of polyvinyl alcohol, but is suitably from 5 to 35% by weight based on polyvinyl alcohol. Preferably it is in the range of 8 to 30% by weight.

The solution for in-line addition of boric acid is prepared by dissolving in a solvent mainly composed of water so that the concentration of boric acid becomes about 1 to 10% by weight. A flow rate is set according to the concentration, and a predetermined amount of boric acid is added to a predetermined amount of the coating solution controlled by a flow meter.

The ink receiving layer of the present invention preferably contains a cationic compound. Examples of the cationic compound include a cationic polymer and a water-soluble metal compound. Examples of the cationic polymer include polyethyleneimine, polydiallylamine, polyallylamine, alkylamii polymer, JP-A-59-20696 and JP-A-59-20696.
No. 33176, No. 59-33177, No. 59-15
No. 5088, No. 60-11389, No. 60-4999
No. 0, No. 60-83882, No. 60-109894
No. 62-198493, No. 63-49478,
Nos. 63-115780, 63-280681, JP-A-1-40371, JP-A-6-234268, and 7-
Polymers having primary to tertiary amino groups and quaternary ammonium bases described in JP-A Nos. 125411 and 10-193776 are preferably used. The molecular weight of these cationic polymers is preferably 5,000 or more, more preferably about 5,000 to 100,000.

The amount of the cationic polymer used is 1 to 10% by weight, preferably 2 to 7% by weight, based on the inorganic fine particles.

The water-soluble metal compound used in the present invention includes, for example, water-soluble polyvalent metal salts. Water-soluble salts of metals selected from calcium, barium, manganese, copper, cobalt, nickel, aluminum, iron, zinc, zirconium, chromium, magnesium, tungsten, and molybdenum. Specifically, for example, calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate, chlorinated chloride Cupric, ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride,
Cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel ammonium sulfate hexahydrate, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum sulfite, Aluminum thiosulfate, poly aluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate,
Ferrous bromide, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, zirconium acetate, zirconium chloride, chloride Zirconium oxide octahydrate, zirconium hydroxychloride, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, magnesium citrate nonahydrate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphate n Hydrate, 12-tungstosilicic acid 26-hydrate, molybdenum chloride, 12-molybdophosphate n-hydrate and the like.

In the present invention, a water-soluble aluminum compound or a water-soluble compound containing a Group 4A element of the periodic table is particularly preferable in terms of water resistance, weather resistance, and prevention of cracking of inorganic fine particles. As the water-soluble aluminum compound, for example, as an inorganic salt, aluminum chloride or a hydrate thereof, aluminum sulfate or a hydrate thereof, ammonium alum and the like are known. Further, there is a basic polyaluminum hydroxide compound which is an inorganic aluminum-containing cationic polymer. Particularly, a basic polyaluminum hydroxide compound is preferable.

The basic polyaluminum hydroxide compound has a main component represented by the following general formula 1, 2 or 3, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ ,
It is a water-soluble polyaluminum hydroxide stably containing basic and high-molecular polynuclear condensed ions such as [Al ₁₃ (OH) ₃₄ ] ⁵⁺ , [Al ₂₁ (OH) ₆₀ ] ³⁺ , and the like. .

[Al ₂ (OH) _n Cl _6-n ] _m Formula 1 [Al (OH) ₃ ] _n AlCl ₃ Formula 2 Al _n (OH) _m Cl _(3n-m) 0 <m <3n Formula 3

These are water treatment agents under the name of polyaluminum chloride (PAC) from Taki Chemical Co., Ltd., and polyaluminum hydroxide (Paho) from Asada Chemical Co., Ltd. It is marketed by RIKEN GREEN under the name Purachem WT and from other manufacturers for the same purpose, and various grades are readily available. In the present invention, these commercial products can be used as they are,
Some substances have an inappropriately low pH, and in such a case, the pH can be appropriately adjusted and used.

The water-soluble compound containing a Group 4A element in the periodic table used in the present invention is not particularly limited as long as it is water-soluble, but a water-soluble compound containing titanium or zirconium is preferred.
For example, as a water-soluble compound containing titanium, titanium chloride,
Titanium sulfate, as water-soluble compounds containing zirconium, zirconium acetate, zirconium chloride, zirconium oxychloride, zirconium hydroxychloride, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium ammonium carbonate, zirconium potassium carbonate, zirconium sulfate And zirconium fluoride compounds are known. Some of these compounds have an inappropriately low pH. In such a case, the pH can be appropriately adjusted and used. In the present invention, the term "water-soluble" refers to a condition in which 1% by weight or more is dissolved in water at normal temperature and normal pressure.

In the present invention, the content of the water-soluble metal compound in the ink receiving layer is from 0.1 g / m ^{2 to} 10 g / m ² .
m ^2, preferably from ^{0.2g / m 2 ~5g / m 2} .

Two or more of the above-mentioned cationic compounds can be used in combination. For example, a cationic polymer and a water-soluble metal compound may be used in combination.

The ink receiving layer in the present invention can contain various oil droplets in order to improve the brittleness of the film. Such oil droplets include hydrophobic high-boiling organic solvents having a solubility in water at room temperature of 0.01% by weight or less (for example, liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, etc.) and polymer particles ( For example, particles obtained by polymerizing one or more polymerizable monomers such as styrene, butyl acrylate, divinylbenzene, butyl methacrylate, and hydroxyethyl methacrylate) can be contained. Such oil droplets can be preferably used in the range of 10 to 50% by weight based on the hydrophilic binder.

In the present invention, a surfactant can be added to the ink receiving layer. The addition amount of the surfactant is preferably 0.001 to 5 g, more preferably 0.01 to 5 g, per 100 g of the binder constituting the ink receiving layer.
３3 g.

In the present invention, the ink-receiving layer further contains a coloring dye, a coloring pigment, a fixing agent for the ink dye, an ultraviolet absorber, an antioxidant, a dispersant for the pigment, an antifoaming agent, a leveling agent, a preservative, and a fluorescent agent. Various known additives such as a whitening agent, a viscosity stabilizer, and a pH adjuster can also be added.

In the present invention, the coating method is not particularly limited, and a known coating method can be used. For example,
There are a slide bead method, a curtain method, an extrusion method, an air knife method, a roll coating method, a ked bar coating method, and the like. Among the above-mentioned coating methods, a slide bead method, a curtain method, and an extrusion method, which are pre-metering types, are particularly preferably used.

In the present invention, one ink receiving layer is provided on the support, but an ink absorbing layer, an ink fixing layer, an intermediate layer, a protective layer and the like may be further provided.

As the support used in the present invention, a water-resistant support is preferably used. For example, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, diacetate resins, triacetate resins,
A resin film such as an acrylic resin, a polycarbonate resin, a polyvinyl chloride, a polyimide resin, a cellophane, a celluloid, etc., and a support in which paper is coated (laminated) with a polyolefin resin such as polyethylene or polypropylene,
Furthermore, a glass plate etc. are mentioned.

These supports may be transparent or opaque. The thickness of the water-resistant support used in the present invention is preferably about 50 to 200 μm.

A preferred support in the present invention is a paper coated with polyethylene terephthalate or polyolefin resin. Hereinafter, the polyolefin resin-coated paper will be described in detail.

The base paper constituting the polyolefin resin-coated paper is not particularly limited, and generally used paper can be used, and more preferably, a smooth base paper used for a photographic support, for example, is preferable. As the pulp constituting the base paper, natural pulp, recycled pulp, synthetic pulp or the like may be used alone or in combination of two or more. This base paper contains sizing agents, paper strength agents,
Additives such as fillers, antistatic agents, optical brighteners, dyes, etc. are compounded.

Further, a surface sizing agent, a surface paper strengthening agent, a fluorescent whitening agent, an antistatic agent, a dye, an anchoring agent and the like may be coated on the surface.

The thickness of the base paper is not particularly limited. However, it is preferable that the base paper has good surface smoothness, for example, by applying a pressure by a calender or the like during or after papermaking, and has a basis weight of 30%. ~250g / m ² is preferred.

As the resin of the resin-coated paper, a polyolefin resin or a resin curable by an electron beam can be used.
The polyolefin resin is a low-density polyethylene, high-density polyethylene, polypropylene, polybutene, a homopolymer of an olefin such as polypentene or a copolymer of two or more olefins such as an ethylene-propylene copolymer and a mixture thereof, Those having various densities and melt viscosity indices (melt index) can be used alone or in combination.

In the resin of the resin-coated paper, white pigments such as titanium oxide, zinc oxide, talc, calcium carbonate, etc., fatty acid amides such as stearamide, arachidic amide, zinc stearate, calcium stearate, stearic acid Aluminum, fatty acid metal salts such as magnesium stearate, antioxidants such as Irganox 1010 and Irganox 1076, blue pigments and dyes such as cobalt blue, ultramarine blue, cecilian blue, and phthalocyanine blue, cobalt violet, fast violet, and manganese purple It is preferable to add various additives such as magenta pigments and dyes, fluorescent brighteners and ultraviolet absorbers in an appropriate combination.

The resin-coated paper as a support preferably used in the present invention is produced by a so-called extrusion coating method in which, in the case of a polyolefin resin, a heat-melted resin is cast on a running base paper, both sides of which are made of resin. Coated. In the case of a resin that is cured by an electron beam, the resin is applied by a commonly used coater such as a gravure coater or a blade coater, and then irradiated with an electron beam to cure and coat the resin. Further, before coating the resin on the base paper, the base paper is preferably subjected to an activation treatment such as a corona discharge treatment or a flame treatment. The surface (surface) of the support on which the ink receiving layer is applied has a glossy surface, a matte surface, and the like, depending on the application, and the glossy surface is used particularly advantageously. It is not necessary to coat the back surface with a resin, but it is preferable to coat the resin from the viewpoint of curling prevention. The back surface is usually a matte surface, and the front surface or both front and back surfaces can be subjected to an activation treatment such as a corona discharge treatment or a flame treatment as required. The thickness of the resin coating layer is not particularly limited, but is generally 5 to 50 μm thick on the surface or on both sides.

The support in the present invention may be coated with various back coat layers for antistatic properties, transport properties, curling prevention properties, and the like. The back coat layer can contain an inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, a latex, a curing agent, a pigment, a surfactant and the like in an appropriate combination.

[0058]

EXAMPLES The present invention will be described below in detail with reference to examples, but the contents of the present invention are not limited to the examples.

Example 1 As supports, LBKP (50 parts) and LBSP (50 parts) were used.
Part) of a pulp blend of 120 g / m ^{2 and} a resin composition comprising low-density polyethylene (70 parts), high-density polyethylene (20 parts) and titanium oxide (10 parts) applied to the surface of 25 g / m ^2. And high-density polyethylene (50
Parts) and a low-density polyethylene (50 parts) resin coating paper prepared by applying 25 g / m ² .

The ink receiving layer coating solution shown below was prepared so that the fumed silica had a solid content of 8% by weight.
After the coating solution was aged at 38 ° C. for 3 hours, the amount of moisture applied to the support was 238 g / m 2 using a slide bead coating device.
^The flow rate was set so as to be ² , and the coating and drying were performed. This is referred to as Comparative Example 1.

<Ink receiving layer coating liquid A> 100 parts of fumed silica (average primary particle diameter 7 nm, specific surface area 300 m ² / g by BET method) Dimethyl diallyl ammonium chloride homopolymer 2 parts (Daiichi Kogyo Seiyaku Co., Ltd.) Manufacture, Sharoll DC902P, molecular weight 9000) Basic polyaluminum hydroxide 3 parts (trade name: Hyurachem WT, manufactured by Riken Co., Ltd.) Boric acid 8 parts Polyvinyl alcohol 22 parts (Saponification degree 88%, average polymerization degree 3500) Activator 0.3 parts

<Preparation of Comparative Example 2> An ink jet recording material was prepared in the same manner as in Comparative Example 1 except that boric acid in the ink receiving layer coating solution A was changed to 5 parts.

<Preparation of Comparative Example 3> An ink jet recording material was prepared in the same manner as in Comparative Example 1 except that boric acid in the ink receiving layer coating solution A was changed to 3 parts.

<Preparation of Invention 1> Boric acid was removed from the above-mentioned ink-receiving layer coating liquid A to prepare a coating liquid. Separately, a 5% by weight aqueous solution of boric acid was prepared as a liquid for in-line addition. The flow rate of this in-line addition liquid is set so that the amount of applied moisture becomes 11.4 g / m ² (corresponding to the added amount of boric acid of 3 parts). did. Other conditions are the same as those in Comparative Example 1.

The ink-receiving layer-coated surface of each of the ink jet recording materials prepared as described above was visually observed,
The crack was evaluated. At the same time, the breaking was evaluated as follows.

The breakage is caused by the curvature when a crack is formed on the surface when an unprinted ink jet recording material is cut into a size of 2 cm × 8 cm, and the printed surface is bent in the long side direction. It was evaluated by measuring the radius. The smaller the radius of curvature, the better.

As a result of the evaluation, in Comparative Example 1, no cracks occurred, but breakage occurred when the radius of curvature was 20 mm or more. In Comparative Example 2, cracks occurred slightly, and breakage occurred at a radius of curvature of 10 to 15 mm. Comparative Example 3
Did not break even when the radius of curvature was 5 mm, but strongly cracked. In the present invention 1, no crack was generated, and no break was generated even when the radius of curvature was 5 mm.

[0068]

As is evident from the above results, cracks and breaks can be prevented simultaneously by using the manufacturing method of the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic view showing steps of a coating apparatus from a coating liquid storage tank of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Storage tank of application liquid 3 Storage tank of inline additive liquid 7 Inline mixer 8 Coating device

Claims (4)

[Claims] 1. A method for producing an ink jet recording material comprising an ink receiving layer mainly containing inorganic fine particles and a binder and a crosslinking agent for the binder coated on a support, wherein the ink receiving layer is coated. A method for producing an ink jet recording material, wherein the crosslinking agent is added in-line immediately before coating. 2. The method according to claim 1, wherein the inorganic fine particles are silica synthesized by a gas phase method. 3. The method according to claim 1, wherein the binder is polyvinyl alcohol. 4. The method according to claim 1, wherein the crosslinking agent is boric acid or a salt thereof.