JP2010184391A - Ink jet recording material and method for manufacturing ink jet recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ink jet recording material which maintains the same quality as that when an RC support body is used even though its support body is formed paper. <P>SOLUTION: The ink jet recording material has a support body and an ink receiving layer, the support body having base paper and at least one coating layer containing dye and latex binder, the water absorbency of the surface of the coating layer is 0.1 g/m<SP>2</SP>or higher and 5 g/m<SP>2</SP>or lower for a contact time of 30 seconds by the Cobb Method of JIS P8140, characteristically, the ink receiving layer is positioned on the surface with the coating layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a recording material applied to an ink jet recording system.

  Conventionally, a support for a photographic ink jet recording material is one in which a polyolefin resin layer is coated on both sides of a base paper (so-called resin-coated paper, hereinafter also referred to as an RC support) in terms of texture, smoothness and gloss. It is common. The recording medium provided with the recording layer on the RC support does not cause cockling after printing and has a good gloss, but has a polyolefin resin coating layer on both sides of the base paper. Remains in the recording layer without evaporating. Due to the presence of the high boiling point solvent in the recording layer, the recorded image tends to bleed (also referred to as high humidity bleeding) under high humidity conditions during storage, which is a serious quality problem.

  Patent Document 1, Patent Document 2, Patent Document 3 and the like use a paper base support (support that is not coated with polyolefin resin or the like on both sides of a base paper), and approach the photographic inkjet recording body by a casting method. Is doing. The recording material obtained by the casting method is excellent in smoothness and glossiness, but due to the necessity of using a low air-permeable support, the solvent in the ink penetrates the base paper in a short time after printing, and the apparent cockling However, the touch and texture are not as high as the quality of photography.

  Although it is a casting method, there is an attempt to provide an undercoat layer containing a pigment having a small pore volume and a latex adhesive for the purpose of suppressing cockling and improving printing bleeding (Patent Document 4). In order to impart, the air permeability of the support is indispensable. There is a limit to increase the air permeability from the productivity, cockling cannot be suppressed as in the RC support, and the texture is insufficient.

JP 2004-167959 A JP 2005-199550 A JP-A 2005-2225070 JP2007-290339

  An object of the present invention is to obtain an ink jet recording body having a quality equivalent to that obtained when an RC support is used while the support is a paper base. The ink jet recording material of the present invention has the same level of cockling resistance, smoothness and glossiness as those of the ink jet recording material using the RC support, and the image blur peculiar to the recording material using the RC support. It is an improvement.

  The inventors have studied paper-based supports. In the case of a paper-based support, high-humidity bleeding is better than that of an RC-based support. This is presumably due to the action of the paper-based support absorbing the ink solvent component and separating it from the color material component. On the other hand, there is a problem that cockling is likely to occur. Cockling occurs when the ink solvent during recording permeates the base paper from the ink receiving layer. On the other hand, high-humidity bleeding occurs due to the presence of the ink solvent in the ink receiving layer even after a lapse of time after recording. In order to solve the conflicting problems, the inventors conducted extensive research on the paper-based support, and as a result, provided a coating layer containing a pigment and a latex binder on the base paper, and the coating layer was formed. The inventors have found that this can be achieved by adjusting to a specific water absorption, and have reached the present invention.

The present invention is as follows. That is,
(1) In an inkjet recording body having a support and an ink-receiving layer having ink jet recording suitability, the support has a base paper and at least one coating layer containing a pigment and a latex binder, and the coating The water absorption of the surface of the working layer is 0.1 g / m ² or more and 5 g / m ² or less at a contact time of 30 seconds according to the Cobb method of JIS P8140, and the surface having the coating layer has an ink receiving layer. Inkjet recording body.

(2) The ink jet recording material according to (1), wherein the ink receiving layer is a layer mainly containing inorganic fine particles having an average particle diameter of 700 nm or less and containing polyvinyl alcohol as an adhesive.
The ink receiving layer preferably further contains a material having crosslinkability with respect to polyvinyl alcohol.

(3) The inkjet recording material according to (1) or (2), wherein the coating layer has two or more layers.
Of the two or more coating layers, one layer is preferably a barrier layer.
The pigment / binder ratio of the barrier layer is preferably 20 to 250/100, more preferably 40 to 230/100, and still more preferably 70 to 200/100.

(4) The ink jet recording material according to any one of (1) to (3), wherein an elongation measured under the following measurement conditions is 0.05% or less.
"Measurement condition"
Green solid printing 18cm wide x 5cm long on an A4 inkjet recording medium conditioned at a temperature of 23 ° C and a humidity of 50%, and after printing for 2 minutes in an environment of a temperature of 23 ° C and a humidity of 50% The lateral length (Lcm) is measured, and the elongation is calculated by the following formula.
Elongation rate (%) = (L−18) × 100 / L
The elongation percentage is preferably 0.03% or less. More preferably, the elongation is 0.01% or less.

(5) A pigment and a latex binder are contained on the base paper so that the water absorption of the coating layer surface is 0.1 g / m ² or more and 5 g / m ² or less at a contact time of 30 seconds according to the Cobb method of JIS P8140. A method for producing an ink jet recording material, comprising forming a support by forming at least one coating layer, and forming an ink receiving layer on the coating layer.
(6) An undercoat coating solution containing at least a material having crosslinkability with respect to polyvinyl alcohol and inorganic fine particles having an average particle diameter of 700 nm or less are the main components on the coating layer, and polyvinyl alcohol is contained as an adhesive. The method for producing an ink jet recording material according to (5), wherein the ink receiving layer is formed by applying a coating liquid for the ink receiving layer.
The coating amount of the crosslinkable material is preferably 0.1 g / m ² or more. The crosslinkable material is preferably boric acid and / or borate.

(7) The method for producing an ink jet recording material according to (6), wherein the undercoat coating liquid contains a pigment and a latex binder.
The pigment for the undercoat layer is preferably at least one selected from calcium carbonate and kaolin.

  The ink jet recording material of the present invention has cockling suppression suitability and surface glossiness close to a recording material in which an RC support is provided with an ink receiving layer. Furthermore, high-humidity bleeding, which is a problem peculiar to a recording body using an RC support, is also prevented. That is, the ink jet recording medium has the advantages of the RC support and the paper support and overcomes the disadvantages.

[Support]
The support used for the ink jet recording material of the present invention has a structure having a base paper and at least one coating layer containing a pigment and a latex binder. The water absorption of the coating coating layer surface is in contact time 30 seconds by Cobb method JIS P8140, it is necessary that 0.1 g / ^{m 2} or more 5 g / ^{m 2} or less. When the water absorption is less than 0.1 g / m ² , moisture resistance bleeding tends to occur when the barrier property of the support is too high. If the water absorption exceeds 5 g / m ² , cockling cannot be prevented if the barrier property is insufficient. As the support exhibiting such water absorption, selection of base paper, blending of coating layer, coating amount, laminating method of coating layer, and the like can be prepared.

"Base paper for support"
There is no restriction | limiting in particular as a base paper, According to the objective, it can select suitably. Generally, it is comprised as a main component the wood pulp and the filler contained as needed. As the wood pulp, various chemical pulps, mechanical pulps, regenerated pulps and the like can be used, and these pulps can be beaten by a beating machine in order to adjust paper strength, papermaking suitability, and the like. The beating degree (freeness) of the pulp is not particularly limited, but is generally about 250 to 550 ml (CSF: JIS P8121). It is preferable to adjust to about 300-500 ml.

  Fillers are blended for the purpose of imparting opacity and the like, and include calcium carbonate, clay, kaolin, white clay, talc, titanium oxide, diatomaceous earth, barium sulfate, aluminum hydroxide, magnesium hydroxide and the like. In addition, agglomerates obtained by drying, firing, and pulverizing wastewater (paper sludge, deinking floss, etc.) of a paper mill can also be used. In particular, calcium carbonate is preferable because it becomes a base material with high whiteness and glossiness of the ink jet recording material is enhanced. The content (ash content) of the filler in the paper base material is preferably about 1 to 30%, but if it is too much, the paper strength tends to be weakened, so the preferable content of the filler is 5 to 20%. Note that calcined kaolin and silica may be contained as appropriate.

  In addition to sizing agents, drying and wet paper strength enhancers, fixing agents, cationizing agents, yield improvers, dyes, fluorescent whitening agents, pH adjusters, antifoaming agents, etc. are added to the base paper as auxiliaries. can do. Furthermore, in the size press process of the paper machine, starch, polyvinyl alcohol, cationic resin, etc. can be applied and impregnated to adjust the surface strength, Cobb water absorption, and the like.

  Examples of the sizing agent include fatty acid salts, rosin derivatives such as rosin and maleated rosin, paraffin wax, alkyl ketene dimer, alkenyl succinic anhydride (ASA), compounds containing higher fatty acids such as epoxidized fatty acid amide, and the like. Can be mentioned. Examples of the dry paper strength enhancer include cationized starch, cationized polyacrylamide, anionized polyacrylamide, amphoteric polyacrylamide, and carboxy-modified polyvinyl alcohol. Examples of the wet paper strength enhancer include polyamine polyamide epichlorohydrin, melamine resin, urea resin, and epoxidized polyamide resin. Examples of the fixing agent include polyvalent metal salts such as aluminum sulfate and aluminum chloride, and cationic polymers such as cationized starch.

Density of the base paper is in the range of 0.6 to 1.2 g / cm ^3, preferably 0.7~1.0g / cm ³ in order to give texture possessed by the RC support, from 0.80 to 0 .95 g / cm ³ is more preferable. The thickness of the base paper is not particularly limited, and is usually 50 to 500 μm. 100 to 300 μm is preferable and 150 to 250 μm is more preferable in view of paper stiffness and rigidity. There is no restriction | limiting in particular in the basic weight of the said base paper, 50-300 g / m < ² > is preferable, and 100-250 g / m < ² > is more preferable from balance with rigidity and a feeling of weight.

"Coating layer of support"
The coating layer on the surface of the support on the side where the ink receiving layer is provided is a layer containing a pigment and a latex binder, and the coating layer surface has a specific range of barrier properties, that is, a water absorption of JIS P8140. If the contact time by the Cobb method is 30 seconds, the coating layer is not particularly limited as long as it is 0.1 g / m ² or more and 5 g / m ² or less.
By incorporating the pigment, the surface quality derived from the base paper can be suppressed, and the glossiness of the finally obtained recording material surface can be increased. By using a latex binder, water resistance can be imparted. Due to the excellent water resistance, the ink receiving layer can be formed without impairing the surface quality when the ink receiving layer coating liquid is laminated. The coating layer is preferably subjected to a smoothing treatment with a calendar after application. Glossiness is improved by laminating the ink receiving layer on the surface of the smooth coating layer.

In order for the water absorption of the Cobb method (contact time 30 seconds) of JIS P8140 specified in the present invention to be 0.1 g / m ² or more and 5 g / m ² or less, the coating layer has a high barrier property coating. It is preferable to have a layer (hereinafter also referred to as a barrier layer). For example, by increasing the blending amount of the latex binder with respect to the pigment, the film formability is improved and a layer having a high barrier property can be obtained. However, since such a layer may be blocked, it is more preferable to provide a coating layer (hereinafter also referred to as a top coating layer) having a higher pigment ratio than the barrier layer on the barrier layer. In addition, when a barrier layer is directly provided on the base paper, the surface quality derived from the base paper is likely to be produced, so the ratio of the pigment is higher than that of the barrier layer in order to relax the surface quality derived from the base paper between the base paper and the barrier layer. It is preferable to provide a coating layer (hereinafter also referred to as an undercoat layer). As for the coating layer of this invention, the structure formed two or more layers is more preferable.
Commercially available coated paper for printing is one in which a coated layer having a pigment and a latex binder is formed on a base paper, but the barrier property is insufficient and does not satisfy the water absorption specified in the present invention. However, by forming a coating layer containing a pigment and a latex binder on the coating layer surface of a commercially available printing coated paper, if it satisfies the specified water absorption, it can be used as a support. it can.

(Pigment)
As a pigment which forms a coating layer, the well-known pigment which can be used with the coating paper for printing etc. can be illustrated. Examples thereof include calcium carbonate, kaolin, calcined kaolin, clay, calcined clay, zinc oxide, aluminum hydroxide, satin white, magnesium silicate, magnesium carbonate, titanium dioxide, and plastic pigment. These can also use multiple types together. The particle diameter of the pigment is not particularly limited, but is preferably 10 μm or less. More preferably, it is 5 μm or less. Most preferably, it is 1.5 μm or less. The smaller the particle diameter, the easier it is to exhibit barrier properties, and the smoothness and glossiness after application of the ink receiving layer tend to be improved. In general commercial products, the average particle size is usually larger than 0.1 μm, so that it is preferably 0.1 μm or more in view of economic rationality. These pigments can be used alone or in combination. Among these, calcium carbonate, kaolin, and satin white are particularly preferable because they have excellent suitability for suppressing cockling and a coating layer with high whiteness is easily obtained. Of these, calcium carbonate and kaolin are preferred. In addition, pigments rich in water absorption and fine pigments such as amorphous silica, colloidal silica, alumina, and zeolite, which are preferable materials for the ink receiving layer of the ink jet recording material, may be used in an amount of 50% or less.

  As the pigment for the barrier layer, the above-mentioned pigments can be selected and used as appropriate, but calcium carbonate and kaolin are particularly preferred because smoothness is easily obtained. In order to obtain higher smoothness, the average particle diameter of calcium carbonate is preferably 0.1 to 2 μm, and more preferably 0.2 to 1 μm. Regarding kaolin, 90% or more of the particles preferably have a particle size of 2 μm or less, and more preferably 95% or more of the particles have a particle size of 2 μm or less. Since kaolin generally has low whiteness, it is preferable to select 88% or more, and more preferably 90% or more. Further, titanium oxide can be contained in order to make the appearance close to the recording material of the RC support. The content is about 1 to 20% of the total pigment, preferably 2 to 10%. In order not to impair the smoothness of the finally obtained recording material, the average particle diameter of titanium oxide is preferably in the range of 0.01 to 2 μm, and more preferably in the range of 0.02 to 1 μm. In addition, colloidal silica is a primary particle and therefore has low absorbency and can be used because it has an effect of improving adhesiveness. In addition, wet silica, dry silica, alumina hydrate, alumina oxide, etc., which are often used as a receiving layer of an ink jet recording body, have a high water absorption and tend to impair the barrier properties. It is necessary to keep it within a range that does not impair the effect.

(Latex binder)
As the latex binder forming the coating layer, a known water-dispersible latex (so-called water-dispersible resin) that can be used for coated paper for printing can be used. For example, vinyls such as conjugated diene copolymer latex such as styrene-butadiene copolymer, methylmethacrylate-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylic copolymer, ethylene-vinyl acetate copolymer, etc. Various binders such as a copolymer copolymer latex, a styrene copolymer latex, a (poly) urethane polymer latex, and the like are used alone or in admixture of two or more. Since the water-dispersible latex is excellent in the cockling inhibiting effect, it is used as the main component of the binder. Styrene / butadiene latex, acrylic polymer latex, and (poly) urethane polymer emulsion are particularly good in terms of binding power and storage stability. Further, the glass transition temperature of the binder is not particularly limited, but a binder having a low glass transition temperature is preferable because smoothness is easily obtained and barrier properties are easily exhibited. A glass transition temperature of about −40 to + 40 ° C. is preferable, and −30 to + 30 ° C. is more preferable. The most preferred range is -20 to + 20 ° C. It should be noted that water-soluble resins (for example, polyvinyl alcohols such as polyvinyl alcohol, cationic polyvinyl alcohol, modified polyvinyl alcohol such as silyl-modified polyvinyl alcohol, casein, soy protein, synthetic proteins, It is possible to add 20 parts or less of starch, cellulose derivatives such as carboxymethylcellulose and methylcellulose) to 100 parts of pigment.

  As the binder for the barrier layer, the aforementioned vaninder can be selected and used as appropriate. From the viewpoint of preventing the cracking of the final ink jet recording sheet, the styrene / butadiene copolymer latex and the acrylonitrile / butadiene copolymer latex can be used. Water dispersible polymers such as (meth) acrylic acid ester (co) polymer latex and urethane resin latex are particularly preferably used. Furthermore, the glass transition temperature of the water-dispersible polymer is preferably −50 to 50 ° C., and more preferably −30 to 30 ° C.

The ratio of the pigment / binder (hereinafter referred to as P / B ratio) of the barrier layer is 0.1 g / m ² or more and 5 g in a specific range of barrier properties, that is, when the water absorption is 30 seconds according to the Cobb method of JIS P8140. / M ² or less, 20 to 250/100, more preferably 40 to 230/100, still more preferably 70 to 200/100. When the amount of pigment is small and the water absorption is less than 0.1 g / m ² , the solvent component does not penetrate into the support and remains in the ink receiving layer even after a lapse of time after recording. May get worse. On the other hand, when the amount of the pigment is large and the water absorption exceeds 5 g / m ² , the barrier property becomes insufficient and cockling tends to occur. In the present invention, by adjusting the water absorption within a specific range, cockling can be suppressed to a level close to that of the RC support, and high-humidity blur of the recorded image that cannot be solved by the RC support can also be improved. .

  When a coating layer other than the barrier layer (undercoating layer, top coating layer) is provided, the pigment / binder ratio (hereinafter referred to as P / B ratio) of the coating layer is used to suppress the blur caused by the base paper. Preferably it is 100/5-100/100, More preferably, it is 100/10-100/50. If the P / B ratio is more than 100/5, the coating film strength becomes weak, paper dust is likely to be produced, and the coating film may be peeled off. On the other hand, if the binder component is more than 100/100, blocking may occur.

Although the total coating amount of the coating layer of a support body does not have a restriction | limiting in particular, It is about 10-70 g / m < ² >. 20-55 g / m ² is preferred. If the amount is less than 10 g / m ² , unevenness derived from the base paper cannot be suppressed, and if it is more than 70 g / m ² , the effect for obtaining smoothness is saturated, and the productivity and economy are lowered.
The coating amount of the barrier layer is a specific range of barrier properties, that is, a water absorption of 0.1 g / m ² or more and 5 g / m ² or less is particularly obtained in a contact time of 30 seconds according to the Cobb method of JIS P8140. Although there is no restriction | limiting, It is about 1-20 g / m < ² > among the said total coating amount. 2-15 g / m < ² > is preferable, More preferably, it is 3-10 g / m < ² >. If the water absorption is less than 0.1 g / m ² due to an excessive coating amount, the high-humidity blur of the image may be deteriorated. On the other hand, if the water absorption exceeds 5 g / m ² due to insufficient coating amount, the barrier property becomes insufficient and cockling tends to occur.

The coating layer is preferably smoothed after coating and drying. The measured value of Oken type smoothness (J.TAPPI No. 5B) on the surface of the support of the present invention is preferably 2000 seconds or more, and more preferably 5000 seconds or more. The method for the smoothing treatment is not particularly limited, and examples thereof include calendar treatment and cast coating treatment, but calendar treatment is more preferable. It is one of the most preferred forms that calender treatment is performed so that the coated surface is in contact with the calendar roll metal surface. The calendar pressure (linear pressure) is preferably 50 to 400 Kg / cm, more preferably 100 to 300 Kg / cm, and most preferably 150 to 250 Kg / cm. If the calendar pressure is too low, smoothness is difficult to obtain, and if it is too high, the coated surface may stick to the calendar roll. In order to obtain higher smoothness, the paper surface temperature of the support just before the calendar is 20 to 90 ° C, more preferably 30 to 50 ° C. If the paper surface temperature is too low, the latex is difficult to soften and the smoothing effect is difficult to obtain. On the other hand, if the paper surface temperature is too high, a problem of sticking to the calendar roll may occur. The surface temperature of the calendar metal roll is preferably 5 ° C to 60 ° C, more preferably 10 ° C to 45 ° C. In addition, the calendar processing speed is preferably in the range of 100 to 1200 m / min, more preferably 200 to 700 m / min. If the calendar speed is slow, it tends to stick to the calendar roll and the coating layer may peel off, but if it is too fast, the smoothing effect will be reduced.

(Other materials)
In the coating layer other than the barrier layer and the barrier layer of the support, as other components, dispersants, thickeners, antifoaming agents, antistatic agents, antiseptics, fluorescence used in the production of general coated paper Various auxiliary agents such as dyes, colorants, ultraviolet absorbers and the like are appropriately added. In particular, in order to increase the apparent whiteness, a colorant (fluorescent whitening agent, colored pigment, dye, etc.) can be blended.

(Coating method)
The coating layer (barrier layer, top coating layer, undercoating layer) of the support can be coated by a known coating method. For example, various known coating apparatuses such as blade coaters, air knife coaters, roll coaters, bar coaters, gravure coaters, rod blade coaters, lip coaters, curtain coaters, slide beads, slide hoppers, and die coaters such as slot dies. You can choose. A blade coater is the best way to increase smoothness and productivity.

"Back layer"
The support of the present invention preferably has a back layer from the viewpoint of product curl, transportability, touch, texture adjustment and the like. The back layer is composed of a general coating layer such as a coating layer composed of a pigment / binder, a resin coating layer, or a resin laminate layer. Of these, a coating layer mainly composed of a pigment / latex binder is particularly preferred. The pigment and binder constituting the back layer are appropriately selected from those described above. In order to bring the touch and texture closer to those of an ink jet recording material using an RC support, the inventors have intensively studied. As a result, it is more effective to use pigments containing kaolin, clay, calcium carbonate, and binders based mainly on latex. Is. In consideration of curling, blocking, transportability, touch, and texture, the P / B ratio is about 100/5 to 100/100. 100/10 to 100/60 is more preferable. The coating amount is about ² to 40 g / m ² , more preferably 5 to 30 g / m ² , and most preferably 10 to 25 g / m ² .
For example, the coating layer coating solution of the support of the present invention can be used for the back layer. Further, the back surface may be further treated with an antistatic agent, an antiblocking agent or the like for a transportability improving process, an antistatic process, or an antiblocking process. The treatment can be performed before or after the ink receiving layer is formed.

(Ink receiving layer)
The ink receiving layer is not particularly limited as long as it is a layer having ink jet recording suitability. The ink receiving layer may be formed of two or more layers. For example, each layer can be configured to be functionally separated, such as an absorbing layer that mainly absorbs the solvent component in the ink on the support side and a receiving layer that holds the coloring component in the ink on the surface side. Moreover, the gloss expression layer for providing glossiness can also be laminated | stacked on the outermost layer.

  It is preferable to form the ink receiving layer with inorganic fine particles having an average particle diameter of 700 nm or less as a main component because a recording material with high glossiness is obtained. In this case, cracks are likely to occur at the time of production (particularly when the ink receiving layer is applied and dried). , Also referred to as a crosslinking agent), it is possible to suppress cracking of the ink receiving layer.

"Undercoating liquid"
The crosslinking agent may be blended in the ink receiving layer coating solution, but the coating solution tends to have a high viscosity and the production conditions become severe. However, after applying the primer coating solution containing the crosslinking agent, the ink receiving layer coating solution is applied. When the liquid is applied, the crosslinking agent blended in the undercoat coating liquid crosslinks with the polyvinyl alcohol in the ink receiving layer coating liquid, so that cracks can be suppressed without employing strict manufacturing conditions.
A pigment and an adhesive agent can be mix | blended with this undercoat liquid. In this case, a pigment coating layer (hereinafter also referred to as an undercoat layer) is formed between the support and the ink receiving layer. The present invention also includes an embodiment having an undercoat layer, and the water absorption specified in the present invention is the surface of the surface to be coated before applying the ink receiving layer (the undercoat layer if there is an undercoat layer). It is a measured value.

  The undercoat coating solution contains at least a material (crosslinking agent) having crosslinkability with respect to polyvinyl alcohol contained in the ink receiving layer in order to prevent cracking of the ink receiving layer. In the present invention, in particular, since the support has a barrier property, the penetration of the crosslinking agent into the support can be suppressed, and the ink receiving layer can be efficiently provided with a minimum amount of the crosslinking agent.

(Crosslinking agent)
The cross-linking agent is not particularly limited as long as it has cross-linkability with respect to polyvinyl alcohol contained as an adhesive in the ink receiving layer coating liquid. For example, a boron compound, an epoxy compound, a glycidyl compound, Zirconium compounds, titanate compounds, aluminum compounds, chromium compounds and the like can be mentioned. Among these crosslinking agents, boron compounds are preferred and boric acid and / or borates are more preferred because of the rapid progress of thickening or gelation when combined with polyvinyl alcohol.
Examples of boric acid include orthoboric acid, metaboric acid, hypoboric acid, tetraboric acid, and pentaboric acid. Moreover, as a borate, these sodium salt, potassium salt, ammonium salt, etc. are mentioned. Among these, orthoboric acid and disodium tetraborate are preferable. Disodium tetraborate _{(composition:} Na ₂ B 4 _{O 7)} is borax (sodium hydrous borate minerals, _{composition: N a 2B 4 O 7 ·} 10H 2 O) is used as a.
These cross-linking agents may be used in combination of two or more depending on the effect of preventing cracking and cracking of the ink receiving layer and other performances. In particular, it is preferable to use boric acid and borax in combination because high concentration dissolution is possible by mixing boric acid and borax.

The coating amount of the cross-linking agent is preferably adjusted to be 0.1 g / m ² or more in terms of solid content. If it is less than 0.1 g / m ² , the polyvinyl alcohol in the ink receiving layer is not sufficiently crosslinked, and the coating film tends to crack.

"Undercoat"
The undercoat coating solution may be an aqueous solution of a crosslinking agent or a coating solution containing a pigment and a binder in addition to the crosslinking agent, but in the case of the latter coating solution containing a pigment and a binder, the undercoat layer The surface quality is further improved and the gloss of the finally obtained recording material surface can be increased, which is preferable.

(Pigment)
As the pigment that can be used in the undercoat layer, the pigments exemplified in the above-mentioned support layer can be appropriately selected and used, and a plurality of these can be used in combination. Since smoothness is easily obtained, calcium carbonate and kaolin are particularly preferable. In order to obtain higher smoothness, the average particle diameter of calcium carbonate is preferably 0.1 to 2 μm, and more preferably 0.2 to 1 μm. Regarding kaolin, 90% or more of the particles preferably have a particle size of 2 μm or less, and more preferably 95% or more of the particles have a particle size of 2 μm or less. Since kaolin generally has low whiteness, it is preferable to select 88% or more, and more preferably 90% or more. Further, titanium oxide can be contained in order to make the appearance close to the recording material of the RC support. The content is about 1 to 20% of the total pigment, preferably 2 to 10%. In order not to impair the smoothness of the finally obtained recording material, the average particle diameter of titanium oxide is preferably in the range of 0.01 to 2 μm, and more preferably in the range of 0.02 to 1 μm.
Note that pigments rich in water absorption and fine pigments such as amorphous silica, colloidal silica, alumina, and zeolite, which are preferable materials for the ink receiving layer of the ink jet recording material, may be used in combination. In addition, colloidal silica is a primary particle and thus has low absorbency, but can be used for the purpose of enhancing adhesiveness.

(binder)
As the binder for the undercoat layer, the binders exemplified in the above-mentioned support layer can be appropriately selected and used. Styrene / butadiene copolymer latex, acrylonitrile / butadiene copolymer latex, (meth) acrylic acid ester (co) polymer latex, urethane from the viewpoint of coating stability and prevention of cracking of the final inkjet recording sheet A water-dispersible polymer such as a resin latex is particularly preferably used.

  The pigment / binder ratio (hereinafter referred to as the P / B ratio) of the undercoat layer is preferably 100/5 to 100/100, more preferably 100/10 to 100/50, in order to suppress blurring derived from the base paper. . If the P / B ratio is more than 100/5, the coating film strength becomes weak, paper dust is likely to be produced, and the coating film may be peeled off. On the other hand, when there are more binder components than 100/100, a crosslinking agent component is concealed and there exists a tendency for a crosslinking effect to fall.

"Ink receiving layer"
The ink receiving layer is not particularly limited as long as it is a layer having ink jet recording suitability, and each known ink receiving layer can be used. A typical example is a layer containing an inorganic pigment, a binder, and a mordant.
(Inorganic fine particles)
In the present invention, it is preferable to form inorganic fine particles having an average particle diameter of 700 nm or less as the main component as the inorganic pigment of the ink-receiving layer because of excellent glossiness, surface smoothness, and ink absorbability. Examples of such inorganic fine particles include gas phase method silica, mesoporous silica, wet method silica, alumina oxide, alumina hydrate, and alumina silicate. Silica, alumina hydrate, and alumina oxide are most preferable. The inorganic fine particles may be surface-treated with an inorganic mordant or an organic mordant described later. Moreover, when it aggregates and an average particle diameter exceeds 700 nm, it is good to give a grinding | pulverization process and a dispersion process. The average particle diameter here is a number average secondary particle diameter obtained by adjusting the concentration of the aqueous dispersion of inorganic fine particles to 1% and obtaining a dynamic light scattering method at 25 ° C.

(Binder)
As the binder used in the ink receiving layer, known binders can be used as the ink receiving layer. However, when the inorganic fine particles are used as a pigment, it is preferable to use polyvinyl alcohol. Polyvinyl alcohol is a water-soluble resin that is cross-linked by a cross-linking agent contained in the undercoat coating liquid. For example, in addition to fully saponified polyvinyl alcohol resin, incompletely saponified polyvinyl alcohol resin, low saponified polyvinyl alcohol resin, cation-modified polyvinyl alcohol One or more kinds of modified polyvinyl alcohol resins such as alcohol resin, silyl-modified polyvinyl alcohol resin, acetoacetyl-modified polyvinyl alcohol resin, and carboxy-modified polyvinyl alcohol resin can be appropriately selected and used.

  The polymerization degree of polyvinyl alcohol used in the ink receiving layer is preferably 3000 to 5000. If the degree of polymerization is less than 3000, the resulting ink-receiving layer tends to have insufficient water resistance. If the degree of polymerization is more than 5000, crystallization of resin molecules is caused when a shear force is applied to the solution or paint. It is easy to handle, and there is a concern that the handleability is lowered, and it is difficult to obtain it practically.

The blending ratio of the polyvinyl alcohol used in the ink receiving layer is suitably adjusted within a range of preferably 1 to 100 parts by mass, more preferably 5 to 50 parts by mass with respect to 100 parts by mass of the inorganic fine particles.
The ratio of the polyvinyl alcohol in the ink receiving layer to the crosslinking agent in the undercoat liquid is preferably 20: 1 to 1: 5, more preferably 5: 1 to 1: 1. By adjusting the mass ratio within this range, it is possible to obtain an ink jet recording sheet which prevents cracks and creases, is superior in ink absorbability, image quality and gloss, and has improved printing bleeding over time.

  The ink receiving layer can contain the crosslinking agent described in the undercoat liquid within a range where the stability of the paint can be obtained. If necessary, the use of a cross-linking agent in the undercoat coating liquid and the ink receiving layer makes it easier to control cracking during the application of the ink absorbing layer. As the crosslinking agent, the aforementioned boron compound is preferable.

  In addition, a crosslinking agent can also be mix | blended with the coating liquid for ink receiving layers, without using the undercoat coating liquid containing a crosslinking agent. In this case, the viscosity of the coating liquid rises and relatively large aggregates of inorganic fine particles are formed, but the type of polyvinyl alcohol, the type of fine pigment, the concentration of the coating liquid, the temperature of the coating liquid, pulverization, dispersion treatment, It can be applied by preparing, which is one of the forms of the present invention.

〔mordant〕
In the present invention, it is preferable that a mordant is contained in the ink receiving layer in order to improve water resistance and aging resistance of the formed image. Examples of mordants include organic mordants and inorganic mordants. The organic mordant and the inorganic mordant may be used alone, respectively, or the organic mordant and the inorganic mordant may be used in combination.

  Examples of the organic mordant include a polymer mordant having a primary to tertiary amino group or a quaternary ammonium base as a cationic group, and an amino group-containing silane coupling agent. These mordants are preferably compounds having an average molecular weight of 500 to 500,000 from the viewpoint of improving ink absorbability of the colorant receiving layer. Inorganic mordants include magnesium, aluminum, calcium, scandium, titanium, vanadium, manganese, iron, nickel, copper, zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, indium, barium, lanthanum, cerium, praseodymium, neodymium And salts or complexes of metals selected from samarium, europium, gadolinium, dysproprosium, erbium, ytterbium, hafnium, tungsten, bismuth. Among these, aluminum-containing compounds, titanium-containing compounds, zirconium-containing compounds, and group IIIB series metal compounds (salts or complexes) are preferable. In addition, it is also possible to coat the surface of the inorganic fine particles with these mordants and use them.

  The mordant content is preferably 1 to 20% by mass and more preferably 2 to 15% by mass with respect to the total solid mass of the ink receiving layer.

(Glossy expression layer)
In order to obtain high gloss, a glossy expression layer composed mainly of a pigment selected from fine monodispersed colloidal pigments and secondary aggregate colloidal pigments, or a mixture of two or more of them, is provided on the ink receiving layer. Is possible. The average particle size of the monodispersed colloidal pigment is 0.01 to 0.2 μm, and 0.02 to 0.1 μm is a preferable range from the balance between absorption and transparency. The secondary aggregate colloidal pigment is preferably alumina oxide or alumina hydrate having an average particle size of 1 μm or less. In order to obtain high gloss, the average particle size is more preferably in the range of 0.02 to 0.5 μm. The method for forming the glossy expression layer is not particularly limited. For example, as described in WO2003-039881, “After the glossy expression layer is provided on the ink receiving layer, it passes through a nip roll having a mirror surface in a wet state. And the “method of forming the gloss developing layer and the ink receiving layer by simultaneous multilayer coating” described in JP-A No. 2004-306610 are effective.

[Other ingredients]
For the ink receiving layer and the gloss developing layer, various known additives, for example, acids, ultraviolet absorbers, antioxidants, fluorescent brighteners, monomers, polymerization initiators, polymerization inhibitors are optionally added. , Anti-bleeding agents, preservatives, viscosity stabilizers, antifoaming agents, surfactants, antistatic agents, matting agents, anti-curling agents, water-proofing agents, and the like.

[Coating method]
For coating the ink receiving layer, various coating devices such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, a die coater, and a slide coater can be used. it can. In the case of a multilayer structure such as a multilayer ink receiving layer or an ink receiving layer and a gloss developing layer, it is effective to use a multilayer slide coater, multilayer curtain coater, or multilayer die coater.

  When the surface of the coating layer is a barrier layer, the ink-receiving layer can be applied online. Since the barrier layer has a large amount of binder components, blocking tends to occur when the barrier layer is wound without being coated with the ink receiving layer.

In the ink jet recording material of the present invention, the elongation measured under the following conditions is preferably 0.05% or less.
"Measurement condition"
Green solid printing 18cm wide x 5cm long on an A4 inkjet recording medium conditioned at a temperature of 23 ° C and a humidity of 50%, and after printing for 2 minutes in an environment of a temperature of 23 ° C and a humidity of 50% The lateral length (Lcm) is measured, and the elongation is calculated by the following formula.
Elongation rate = (L-18) × 100 / L

  When the elongation is 0.05% or less, it can be seen that the barrier layer functions to suppress cockling, and when it exceeds 0.05%, the barrier property of the barrier layer is insufficient. It can be said that the ring cannot be prevented. The elongation is more preferably 0.03% or less, and particularly preferably 0.01% or less. The reason why the elongation is 2 minutes after printing is that the elongation of the base paper is maximized in the state before and after 2 minutes. Incidentally, after 1 minute, the base paper is in the middle of stretching, and after 4 minutes, the base paper once stretched is in a contracted state.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is of course not limited thereto. Moreover, unless otherwise indicated, the part and% in an example are solid content except water, and show a mass part and mass%, respectively.

-Preparation of silica fine particles-
Commercial vapor phase silica (manufactured by Nippon Aerosil Co., Ltd., trade name: Aerosil A200) in an aqueous solution (876 g, 1%) of 2-aminoethyl-3-aminopropyltriethoxysilane (trade name KBE-603, manufactured by Shin-Etsu Chemical Co., Ltd.) ) 120 g and 4 g of lactic acid were added with stirring, dispersed with a sand grinder, then further dispersed with a pressure homogenizer, and the dispersing operation of the sand grinder and the pressure homogenizer was repeated until the average particle size became 0.08 μm, A dispersion was prepared.
In addition, an average particle diameter is a number average secondary particle diameter calculated | required by the dynamic light-scattering method on the conditions of 25 degreeC, adjusting an aqueous dispersion to 1%. As the measuring apparatus, a thick particle size analyzer FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.) was used.

-Ink-receiving layer coating liquid A-
15 parts of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: PVA-235, polymerization degree: 3500, saponification degree: 88.5%) was mixed with 100 parts of the above silica fine particles to prepare a 13% aqueous dispersion.

-Ink-receiving layer coating liquid B-
After adding 1 part of boric acid to 100 parts of the silica fine particles and dissolving, 15 parts of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: PVA-235, polymerization degree: 3500, saponification degree: 88.5%) are added. Mixed to prepare a 13% aqueous dispersion.

-Glossy layer coating liquid A-
To 100 parts of 45 nm cationic colloidal silica (manufactured by Nissan Chemical Co., Ltd., trade name: ST-AKL), 2 parts of the polyvinyl alcohol and 1 part of the cationic release agent (trade name: Pertol N856, manufactured by Modern Science Co., Ltd.) were mixed. A 3% aqueous dispersion was prepared.

Example 1
-Production of base paper A-
To the pulp slurry consisting of 90 parts of LBKP (freeness 440 ml / csf) and 10 parts of NBKP (freeness 510 ml / csf), light calcium carbonate as a filler is added to the pulp solids so as to be 10% in terms of paper ash. As an additive sizing agent, AKD sizing agent (trade name: Size Pine K-902, manufactured by Arakawa Chemical Industries, Ltd.) 0.05% and aluminum sulfate 0.5% were respectively added to prepare a paper stock. Using the stock thus prepared, paper was made and dried with a hybrid type twin wire paper machine to obtain a paper (base paper). Next, an oxidized starch paste (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) with a concentration of 6% is applied to both sides of the base paper thus obtained through a two-roll size press device in terms of double-sided solid content. The base paper A having a rice basis weight of 150 g / m ² was obtained by coating and drying so as to be 1.4 g / m ² .

-Production of support-
Base Paper coating layer coating solution on one surface of the following A A, each side so that each dry weight coating layer coating solution for B on the other side becomes ^{5g / m 2, 15g / m} 2 It was coated using a blade coater and dried. The paper was smoothed by passing through a super calender (8 nip, linear pressure 100 kg / cm, 500 m / min) under the condition of a surface temperature of 25 ° C. to obtain a support. In addition, let the surface which coated the coating liquid A for coating layers be a surface which forms an ink receiving layer. The water absorption of this surface (JIS P8140 Cobb method (contact time 30 seconds)) was 2 g / m ² .

"Coating fluid A for coating layer"
100 parts of heavy calcium carbonate (product name: Softon 3200, manufactured by Shiroishi Calcium Co., Ltd.) was added as a pigment to an aqueous solution containing 0.3 part of a commercially available dispersant (product of Toagosei Co., Ltd., product name: Aron T-50). Dispersed to prepare a slurry. 100 parts of styrene-butadiene copolymer latex (trade name: PT1051, manufactured by Nippon Zeon Co., Ltd., Tg = 10 ° C.) having an average particle size of 110 nm, a carboxy having a degree of etherification of 0.70 to 0.80 as a thickener. 0.2 parts of methylcellulose sodium salt (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Cellogen WSA) and auxiliary agents such as antifoaming agents and dyes are added, and finally the coating has a solid content of 55%. Layer coating solution A was prepared.

"Coating layer coating solution B"
As a pigment, 100 parts of heavy calcium carbonate having a whiteness of 95% and an average particle diameter of 0.7 μm are added to an aqueous solution containing 0.3 part of a commercially available dispersant (manufactured by Toagosei Co., Ltd., trade name: Aron T-50). And dispersed to prepare a slurry. Subsequently, 20 parts of the above-mentioned styrene-butadiene copolymer latex, 0.3 parts of the above-mentioned carboxymethylcellulose sodium salt as a thickener, and auxiliary agents such as an antifoaming agent and a dye were added, and finally A pigment coating layer coating solution A having a solid content concentration of 60% was prepared.

−Preparation of inkjet recording material−
A 0.5% borax aqueous solution is applied onto the support as an undercoat coating solution so that the coating amount is 0.1 g / m ^2, and the ink receiving layer coating solution A is further applied at a coating amount of 15 g / m 2. ^The coating was carried out under the condition of Wet on Wet, and drying was performed with a dryer at 80 ° C. to obtain an ink jet recording material.

Example 2
-Production of support-
A support was obtained in the same manner as in Example 1.
−Preparation of inkjet recording material−
On the said support body, the following coating liquid for undercoat layers was apply | coated so that the coating amount might be 5 g / m < ² >, and it dried. Next, the ink receiving layer coating liquid A was applied so that the coating amount was 15 g / m ^2, and dried with a dryer at 80 ° C. to prepare an ink jet recording material.
"Coating liquid A for undercoat layer"
A slurry was prepared by adding and dispersing 100 parts of the above-mentioned heavy calcium carbonate as a pigment in an aqueous solution containing 0.3 part of a commercially available dispersant (manufactured by Toagosei Co., Ltd., trade name: Aron T-50). Subsequently, 25 parts of a 1: 1 mixture of boric acid and borax as an aqueous solution was stirred and mixed, 15 parts of the above-mentioned styrene-butadiene copolymer latex was added in an amount of 0.1 part of the above-mentioned carboxymethylcellulose sodium salt as a thickener. 3 parts, and auxiliary agents such as an antifoaming agent and a dye were added to finally prepare a coating liquid A for an undercoat layer having a solid content concentration of 55%.

Example 3
-Production of support-
A support was obtained in the same manner as in Example 1 except that 100 parts of heavy calcium carbonate in the coating liquid A for coating layer in Example 1 was changed to 50 parts. The water absorption of the surface on which the ink receiving layer is formed (JIS P8140 Cobb method (contact time 30 seconds)) was 0.5 g / m ² .
−Preparation of inkjet recording material−
An ink jet recording material was produced in the same manner as in Example 2 except that the above support was used.

Example 4
-Production of support-
A support was obtained in the same manner as in Example 1 except that 50 parts of the styrene-butadiene copolymer latex in the coating layer coating solution A of Example 1 was used. The water absorption of the surface on which the ink receiving layer is formed (JIS P8140 Cobb method (contact time 30 seconds)) was 4 g / m ² .
−Preparation of inkjet recording material−
An ink jet recording material was produced in the same manner as in Example 2 except that the above support was used.

Example 5
-Production of support-
One surface below the coating layer coating liquid A of the base paper A, each side so that each dry weight coating layer coating solution for B on the other side becomes ^{5g / m 2, 15g / m} 2 blades It was coated using a coater and dried. Next, 15 g / m ^{2 of} coating layer coating liquid B was further applied onto the coating layer coating liquid A coating surface, dried, and then super calender (8 nip, linear pressure 100 kg / cm ^{2) under} the condition of a surface temperature of 25 ° C. cm, 500 m / min) and smoothed to obtain a support. In addition, let the surface which coated two layers of the coating liquid A for coating layers, and the coating role B for coating layers be a surface which forms an ink receiving layer. The water absorption of this surface (JIS P8140 Cobb method (contact time 30 seconds)) was 1.5 g / m ² .
−Preparation of inkjet recording material−
An ink jet recording material was produced in the same manner as in Example 2 except that the above support was used.

Example 6
-Production of support-
A support was obtained in the same manner as in Example 5.
−Preparation of inkjet recording material−
Using the above support, in the coating liquid A for the undercoat layer of Example 2, the pigments were changed to 50 parts of heavy calcium carbonate and 50 parts of kaolin (manufactured by Imeris Minerals Japan, trade name: Contour Xtreme). In the same manner as in Example 2, an ink jet recording material was produced.

Example 7
-Production of support-
A support was obtained in the same manner as in Example 5.
−Preparation of inkjet recording material−
Using the above support, in the coating solution A for the undercoat layer of Example 2, the pigment was a fine silica colloid solution having an average primary particle size of 12 nm and an average secondary particle size of about 300 nm (trade name: Silojet 703A Grace Devison Co., Ltd.). An ink jet recording material was produced in the same manner as in Example 2 except that the solid content concentration of the coating material was changed to 25%.

Example 8
-Production of support-
A support was obtained in the same manner as in Example 5.
−Preparation of inkjet recording material−
The same procedure as in Example 2 except that the styrene-butadiene copolymer latex was changed to an acrylic acid copolymer latex (trade name: JK7000, manufactured by Meisei Chemical Co., Ltd.), using the above support. An ink jet recording material was prepared in the same manner as in Example 2.

Example 9
-Production of support-
A support was obtained in the same manner as in Example 5.
−Preparation of inkjet recording material−
An ink jet recording material was produced in the same manner as in Example 2 except that the above support was used and the ink receiving layer coating liquid A was changed to the ink receiving layer coating liquid B.

Example 10
The glossy layer coating material A was applied to the inkjet recording material obtained in Example 9 to 1 g / m ² , and a mirror drum (surface temperature: 85 ° C.) and a nip roll so that the coated surface hit the mirror surface while wet. (Line pressure: 150 kg / cm, speed: 100 m / min), and then dried to obtain an ink jet recording material.

Example 11
-Production of support-
In the production of the support of Example 1, instead of the base paper A, the support was prepared in the same manner as in Example 1 except that it was changed to commercially available coated paper ("SA Kanto +" 209 g / m ² , manufactured by Oji Paper Co., Ltd.). Obtained. In addition, let the surface which coated the coating liquid A for coating layers be a surface which forms an ink receiving layer. The water absorption of this surface (JIS P8140 Cobb method (contact time 30 seconds)) was 1 g / m ² .
−Preparation of inkjet recording material−
An ink jet recording material was produced in the same manner as in Example 2 except that the above support was used.

Example 12
-Production of support-
In the production of the support of Example 5, the support was prepared in the same manner as in Example 5 except that instead of the base paper A, a commercially available coated paper ("SA Kanto +" 209 g / m ² , manufactured by Oji Paper Co., Ltd.) was used. Obtained. In addition, let the surface which coated two layers of the coating liquid A for coating layers, and the coating role B for coating layers be a surface which forms an ink receiving layer. The water absorption of this surface (JIS P8140 Cobb method (contact time 30 seconds)) was 0.5 g / m ² .
−Preparation of inkjet recording material−
An ink jet recording material was produced in the same manner as in Example 5 except that the above support was used.

Comparative Example 1
-Production of support-
The back surface of the base paper A was coated with the coating layer coating solution B using a blade coater so that the dry weight was 15 g / m ² and dried. The paper was smoothed by passing through a super calender (8 nip, linear pressure 100 kg / cm, 500 m / min) under the condition of a surface temperature of 25 ° C. to obtain a support. In addition, let the surface in which the coating layer is not formed be a surface in which an ink receiving layer is formed. The water absorption of this surface (JIS P8140 Cobb method (contact time 30 seconds)) was not measurable.
−Preparation of inkjet recording material−
An ink jet recording material was produced in the same manner as in Example 2 except that the above support was used.

Comparative Example 2
-Production of support-
A support was obtained in the same manner as in Example 1 except that 10 parts of the styrene-butadiene copolymer latex in the coating layer coating liquid A of Example 1 was used. The water absorption of the surface on which the ink receiving layer is formed (JIS P8140 Cobb method (contact time 30 seconds)) was 20 g / m ² .
−Preparation of inkjet recording material−
An ink jet recording material was produced in the same manner as in Example 2 except that the above support was used.

Comparative Example 3
-Production of support-
A support was obtained in the same manner as in Example 5 except that 10 parts of the styrene-butadiene copolymer latex in the coating layer coating liquid A of Example 5 was used. The water absorption of the surface on which the ink receiving layer is formed (JIS P8140 Cobb method (contact time 30 seconds)) was 15 g / m ² .
−Preparation of inkjet recording material−
An ink jet recording material was produced in the same manner as in Example 2 except that the above support was used.

Comparative Example 4
-Production of support-
The styrene-butadiene copolymer latex of the coating solution A for coating layer of Example 5 was changed to 100 parts of PVA (trade name: PVA140, manufactured by Kuraray Co., Ltd.) and supported in the same manner as in Example 5 except that no pigment was used. Got the body. The water absorption of the surface on which the ink receiving layer is formed (JIS P8140 Cobb method (contact time 30 seconds)) was 0 g / m ² .
−Preparation of inkjet recording material−
An ink jet recording material was produced in the same manner as in Example 2 except that the above support was used.

Comparative Example 5
-Production of support-
As a support, it changed into the following RC support. The water absorption of the surface on which the ink receiving layer is formed (JIS P8140 Cobb method (contact time 30 seconds)) was 0 g / m ² .

-RC support-
LBKP 100 parts (freeness 400 ml / csf), calcined kaolin (trade name: Ancilex) 5 parts by weight, AKD sizing agent 0.05 parts by weight, sulfuric acid band 1.5 parts by weight, wet paper strength agent 0.5 parts by weight, using the papermaking material consisting of starch 0.75 part by weight papermaking hybrid type twin wire paper machine, a base paper of 150 g / m ² and then dried.
After performing corona discharge treatment on both sides of the base paper, the following polyolefin resin composition 1 mixed and dispersed with a Banbury mixer so that the coating amount is 22 g / m ² on the felt side of the base paper, The polyolefin resin composition ² was applied to the wire surface side of the base paper with a melt extruder (melting temperature: 320 ° C.) having a T-type die so that the coating amount was 30 g / m ² . Next, the felt side of the base paper was cooled and solidified with a mirror-like cooling roll, and the wire side of the base paper was cooled and solidified with a rough cooling roll. An RC support having a smoothness (Oken formula, J.TAPPI No. 5) of 6000 seconds and an opacity (JIS P 8138) of 93% was produced.

"Polyolefin resin composition 1"
35 parts by mass of long-chain low-density polyethylene resin (density 0.926 g / cm ³ , melt index 20 g / 10 min), 50 parts by mass of low-density polyethylene resin (density 0.919 g / cm ³ , melt index 2 g / 10 min) , 15 parts by mass of anatase-type titanium dioxide (Ishihara Sangyo Co., Ltd., trade name: A-220), 0.1 parts by mass of zinc stearate, 0.03 parts by mass of antioxidant (manufactured by Ciba Geigy, trade name: Irganox 1010), Ultramarine (Daiichi Kasei Co., Ltd., trade name: Aoguchi Ultramarine No. 2000) 0.09 parts by mass, fluorescent whitening agent (Ciba Geigy, trade name: UVITEX OB) 0.3 parts by mass.

"Polyolefin resin composition 2"
High-density polyethylene resin (density 0.954 g / cm ³ , melt index 20 g / 10 minutes) 65 parts by mass, low-density polyethylene resin (density 0.924 g / cm ³ , melt index 4 g / 10 minutes) 35 parts by mass.

−Preparation of inkjet recording material−
An ink jet recording material was produced in the same manner as in Example 2 except that the above support was used.

<Evaluation method>
Film-forming properties (coating cracks), glossiness, elongation rate (cockling), high-humidity bleeding of images, and recyclability of the recording medium obtained in Examples 1-12 and Comparative Examples 1-5 Was evaluated by the method shown below. Printing was performed with a commercially available inkjet printer (manufactured by CANON, model: PIXUS iP4200, paper setting: super photo paper, print quality: standard).

-Film-formability of ink receiving layer-
The degree of cracking of the ink receiving layer was visually evaluated.
○: No cracks are observed.
Δ: Slight cracking, but at a level that seems to be practically acceptable.
X: Cracking occurs and there is a problem in practical use.

-Glossiness-
ISO-400 images (“High-definition color digital standard image data ISO / JIS-S
CID ", p13, image name: fruit basket) was printed and visually observed from a lateral angle with respect to the printed portion, and evaluated according to the following four stages.
A: Glossiness close to that of a silver salt photograph.
○: Glossiness superior to gloss printing paper (Ultra OK Kaneto N, made by Oji Paper, art paper).
(Triangle | delta): 23 glossiness close | similar to gloss type printing paper (Ultra OK Kanfuji N, Oji Paper manufacture, art paper).
×: almost no gloss

−Print elongation (cockling) −
Green solid printing 18cm wide x 5cm long on an A4 inkjet recording medium conditioned at a temperature of 23 ° C and a humidity of 50%, and after printing for 2 minutes in an environment of a temperature of 23 ° C and a humidity of 50% The lateral length (Lcm) was measured, and the elongation was calculated by the following formula.
Elongation rate (%) = (L−18) × 100 / L
The greater the elongation, the worse the cockling. If it exceeds 0.10%, the cockling is very conspicuous, and if it is less than 0.05%, the cockling is good, and the appearance is a level at which the difference from the ink jet recording body using the RC support cannot be seen.

-Image bleeding-
The ink-jet recording material was conditioned at 30 ° C. and 80% high-temperature and high-humidity conditions for 24 hours, and then the ISO-400 image (“high-definition color digital standard image data ISO / JIS-SCID”, p13, image name) : Fruit basket). Immediately after printing, the back side of the same recording medium and the printed side were overlapped, and a weight of 300 g was placed thereon. After standing for 3 days under the high temperature and high humidity conditions, the image was observed.
○: Good without blurring of the image.
Δ: Slight bleeding is observed, but there is no practical problem.
X: The bleeding of an image is bad.

-Recyclability-
Like the general coated paper, the support of the present invention was beaten in an aqueous alkaline solution to examine whether or not re-disintegration was possible. The possibility of using recycled paper was evaluated according to the following criteria.
○: Recycled paper can be used at the same level as coated paper.
Δ: Re-disaggregation is difficult, and if it is added to ordinary pulp in a small amount, it can be made into recycled paper.
×: Cannot be disaggregated

  As is apparent from Table 1, the present invention is a recyclable paper-based support, but is cockling-free at the same level as an inkjet recording material using an RC support, and has glossiness and image blur. It is good.

  According to the present invention, it has cockling resistance, surface glossiness, smoothness, and texture similar to those of a recording medium in which an ink receiving layer is provided on an RC support. In addition, there is no blur of the image peculiar to the recording medium using the RC support, and recycling is possible. That is, an ink jet recording body that has the advantages of the RC support and the paper support and overcomes the disadvantages is provided.

Claims (7)

In the inkjet recording medium having a support and an ink receiving layer, the support has a base paper and at least one coating layer containing a pigment and a latex binder, and the water absorption of the coating layer surface is JIS P8140. in the Cobb method by contact time of 30 seconds, 0.1 g / m ² or more 5 g / m ² or less, an ink jet recording material, characterized by having an ink-receiving layer on the surface having the coating coating layer. 2. The ink jet recording material according to claim 1, wherein the ink receiving layer is a layer mainly composed of inorganic fine particles having an average particle diameter of 700 nm or less and containing polyvinyl alcohol as an adhesive. The inkjet recording body according to claim 1, wherein the coating layer has two or more layers. The elongation percentage measured on the following measurement conditions is 0.05% or less, The inkjet recording body as described in any one of Claims 1-3.
"Measurement condition"
Green solid printing 18cm wide x 5cm long on an A4 inkjet recording medium conditioned at a temperature of 23 ° C and a humidity of 50%, and after printing for 2 minutes in an environment of a temperature of 23 ° C and a humidity of 50% The lateral length (Lcm) is measured, and the elongation is calculated by the following formula.
Elongation rate (%) = (L−18) × 100 / L On the base paper, at least one layer containing a pigment and a latex binder so that the water absorption of the coating layer surface is 0.1 g / m ² or more and 5 g / m ² or less at a contact time of 30 seconds according to the Cobb method of JIS P8140. A method for producing an ink jet recording material, comprising: forming a coating layer to obtain a support, and forming an ink receiving layer on the coating layer. An ink receiving layer containing, as a main component, an undercoat coating solution containing at least a material crosslinkable to polyvinyl alcohol, inorganic fine particles having an average particle size of 700 nm or less, and polyvinyl alcohol as an adhesive on the coating layer 6. The method for producing an ink jet recording material according to claim 5, wherein the ink receiving layer is formed by applying a coating liquid. The method for producing an ink jet recording material according to claim 6, wherein the undercoat liquid contains a pigment and a latex binder.