JP2007216686A - Manufacturing method for inkjet recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for inkjet recording paper having a high-recording quality and high gloss close to that of printing paper for photographs. <P>SOLUTION: The manufacturing method for inkjet recording paper comprises the preparation of at least an inkjet recording layer having a pigment and an adhesive on an air-permeable base material, application of a pigment-and-adhesive-containing coating liquid onto the inkjet recording layer and pressing it to the heated mirror surface drum while the coating liquid is still wet or remains re-moisturized, and then drying so as to form a cast-coated layer. As the air-permeable base material, a paper base material is predominantly composed of wood pulp, having an acid content of 1-20%. In accordance with ISO 8791/4;1992, the surface of the paper base material is provided with the cast-coated layer and has a Parker Print Surf roughness of ≤6μm, using a pressure of 490 kPa, and has the air permeability of 10-200 sec/100 cc under J. TAPPI No. 5 B. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording paper, and more particularly, to a method for producing an ink jet recording paper having high gloss, excellent image definition, and ink jet recording suitability.

  Recording by an ink jet printer is used in many fields because of low noise, high speed recording, and easy multi-coloring. As the ink jet recording paper, high-quality paper devised so as to be rich in ink absorbability, coated paper coated with a porous pigment on the surface, and the like are applied. By the way, since all of these sheets are mainly so-called matte inkjet recording sheets having a low surface gloss, an inkjet recording sheet having a high surface gloss and an excellent appearance is desired.

As an ink jet recording paper having a surface gloss, there is a polymer coated glossy paper having an ink jet recording layer mainly composed of a water-soluble resin. However, since this recording paper uses a water-soluble resin and contains almost no pigment, it has high gloss, but has poor ink absorbability and poor water resistance. Not suitable for that.
In addition, it has been proposed to provide a high gloss recording paper using an electron beam curable resin, but in this case as well, the ink absorbability is poor and high density ink jet recording cannot be performed.

In addition to the above-described ink jet recording paper containing resin as a main component, there is an ink jet recording paper containing pigment as a main component and manufactured by a casting method.
The casting method is known as a method for producing glossy printing paper. By coating a coating liquid having a plate-like pigment on the surface of a support, and applying a wet or rewet coating layer to a heated drum surface having a mirror surface and drying, the mirror surface is copied. is there. The obtained printing paper has a high surface gloss and superior surface smoothness compared to other coated papers, and has an excellent printing effect, so it is exclusively used for applications such as high-quality printed materials. .

  However, when the casting method used in printing paper is used for ink jet recording paper, there are various difficulties. That is, the conventional cast coated paper for printing obtains high gloss by copying the mirror drum surface of the cast coater with a film forming material such as an adhesive in the pigment composition constituting the coating layer. . However, the presence of the film-forming substance loses the porosity of the coating layer, and has problems such as extremely reducing ink absorption during ink jet recording. In order to improve the ink absorbability, it is important to make the cast coating layer porous so that the ink can be easily absorbed. For this purpose, it is necessary to reduce the film formability. Reducing the amount of membranous material results in a reduction in white paper gloss. As described above, it has been extremely difficult to satisfy both the surface gloss of the cast coated paper and the ink jet recording suitability at the same time.

  As a method for solving this problem, a copolymer having a glass transition point of 40 ° C. or higher obtained by polymerizing a monomer having an ethylenically unsaturated bond on a base paper provided with a recording layer mainly composed of a pigment and an adhesive. By forming a cast coating layer by applying a coating liquid containing the coalescence as a main component, and pressing and drying the heated mirror drum while the cast coating layer is in a wet state. It has been proposed that an ink-jet recording cast paper having both excellent gloss and ink absorbability can be obtained (for example, see Patent Document 1).

  In recent years, with the expansion of applications such as high speed inkjet recording, high definition of recorded images, and full color, higher gloss, high image quality, and high recording density are desired. In order to achieve such a requirement, at least two ink jet recording layers containing aggregate fine particles having an average particle diameter of secondary particles of 1 μm or less and an adhesive are provided on the substrate, and the surface layer of the ink jet recording layer Has been proposed (see, for example, Patent Document 2).

JP-A-7-89220 JP 2001-10220 A

However, with the above technique, high glossiness and recording quality that are visually comparable to silver salt type photographic paper are not sufficiently achieved. For example, the ink jet recording paper obtained in Japanese Patent Application Laid-Open No. 2001-10220 shows a high gloss value at 75 ° observation, but is visually inferior to photographic printing paper.
The present invention further provides an inkjet recording paper having a high glossiness close to that of photographic printing paper and good recording quality.

  As a result of intensive studies to solve the above problems, the present inventors have achieved by producing a specific base material by forming an ink jet recording layer and a cast coating layer by a casting method. He found what he could do and came up with the invention.

The present invention includes the following aspects.
{1} At least one ink jet recording layer containing a pigment and an adhesive is provided on a gas-permeable substrate, and a coating liquid containing the pigment and the adhesive is applied on the ink jet recording layer. In an inkjet recording paper manufacturing method in which a cast coating layer is formed by press contact with a heated mirror drum and drying while the working liquid is in a wet or rewet state, wood pulp is mainly used as a gas-permeable substrate. Using a paper base material having an ash content of 1 to 20% as a component, the surface on which the cast coating layer is provided conforms to ISO 8791/4: 1992, and the Parker print surf roughness at a pressure condition of 490 kPa is A method for producing an ink jet recording paper, comprising using a base material having a diameter of 6 μm or less and an Oken type air permeability of 10 to 200 seconds / 100 cc.
{2} The method for producing an inkjet recording paper according to {1}, wherein the gas-permeable substrate is a paper substrate mainly composed of wood pulp and having an ash content of 7 to 20%.
{3} The secondary ink in which the pigment of the inkjet recording layer has an average primary particle size of 3 to 40 nm and an average secondary particle size of 10 to 1000 nm selected from the group consisting of silica, aluminosilicate, and alumina. The method for producing an ink jet recording paper according to {1} or {2}, wherein the method is a particle.
{4} The method for producing an ink jet recording paper according to any one of {1} to {3}, wherein the pigment of the ink jet recording layer contains at least one kind of cationic fine silica.
{5} The method for producing an inkjet recording paper according to any one of {1} to {4}, wherein the gas-permeable base material has wood pulp as a main component and calcium carbonate as a filler.
{6} An ink jet according to any one of {1} to {5}, wherein an undercoat layer having a pigment and an adhesive is provided on a gas-permeable substrate, and an ink jet recording layer and a cast coating layer are formed on the undercoat layer. Recording paper manufacturing method.
{7} The method for producing an inkjet recording paper according to {6}, wherein the pigment of the undercoat layer is silica having an average particle diameter of 1 to 20 μm.
{8} The method for producing an inkjet recording paper according to any one of {1} to {7}, wherein the pigment of the cast coating layer contains anionic colloidal silica.
{9} The surface of the cast coating layer according to any one of {1} to {8}, which has a Parker print surf roughness of 4 μm or less under a pressure condition of 490 kPa, in accordance with ISO 8791/4: 1992. Ink jet recording paper manufacturing method.

  The method for producing an ink jet recording paper of the present invention can provide an ink jet recording paper having high glossiness, excellent image sharpness, visually close to a photographic printing paper, and excellent recording suitability.

  The present invention provides at least one inkjet recording layer containing a pigment and an adhesive on a gas-permeable substrate, and coats a coating liquid containing the pigment and the adhesive on the inkjet recording layer, In the method for producing an ink jet recording paper in which a cast coating layer is formed by pressing and drying a heated mirror drum while the coating liquid is in a wet or rewet state, (A) The surface on which the cast coating layer is provided conforms to ISO 8791/4: 1992, the Parker print surf roughness at a pressure condition of 490 kPa is 6 μm or less, and An inkjet recording paper manufacturing method using a base material having a temperament of 10 to 200 seconds / 100 cc.

About air permeable substrate
The gas permeable substrate is a gas permeable substrate, and an acid paper used for general coated paper or a paper substrate such as neutral paper is appropriately used.
The paper base is composed mainly of wood pulp and a filler containing it as necessary.
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-P-8121). In order to improve smoothness, it is desirable to advance the beating degree. However, when recording on paper, the paper blur and the blur of the recorded image caused by the moisture in the ink often give better results if the beating is not advanced. . Accordingly, the freeness is preferably about 300 to 500 ml.

  The filler is blended for the purpose of imparting opacity or adjusting the ink absorbability, and calcium carbonate, calcined kaolin, silica, titanium oxide and the like can be used. In particular, calcium carbonate is preferable because it becomes a substrate with high whiteness and glossiness of the ink jet recording paper is enhanced. The content (ash content) of the filler in the paper substrate is 1 to 20%.

A sizing agent, a fixing agent, a paper strength enhancer, a cationizing agent, a yield improving agent, a dye, a fluorescent brightening agent, and the like can be added to the paper base as an auxiliary agent. Furthermore, in the size press process of the paper machine, starch, polyvinyl alcohol, cationic resin and the like can be applied and impregnated to adjust the surface strength, sizing degree, and the like. The Steecht sizing degree (as 100 g / m ² paper) is preferably about 1 to 200 seconds. If the sizing degree is low, there may be operational problems such as wrinkling at the time of coating, and if it is high, the ink absorbability may be lowered, and curling and cockling after printing may be remarkable. A more preferred range of sizing is 4 to 120 seconds. Although the basic weight of a base material is not specifically limited, It is about 20-400 g / m < ² >.

In the present invention, (a) First, as a gas permeable substrate, the surface on which the cast coating layer is provided conforms to ISO 8791/4: 1992, and the Parker print surf roughness at a pressure condition of 490 kPa is 6 μm or less. Use a substrate.
In the present invention, in order to select a gas-permeable substrate to be used, the surface roughness is defined by Parker Print Surf roughness under a pressure condition of 490 kPa. Since this is a state in which the measurement pressure is higher than the Beck smoothness and is close to the manufacturing conditions (the press pressure of the mirror drum), the substrate is selected using this measurement method. Preferably, it is 5.5 or less μm. Incidentally, if it exceeds 6 μm, it tends to be an ink jet recording paper having inferior glossiness and image sharpness.

(A) Moreover, the base material whose Oken type | formula air permeability (J.TAPPI No.5 B) of a gas-permeable base material is 10-200 second / 100cc is used. Preferably it is 10-150 seconds / 100cc, More preferably, it is 10-100 seconds / 100cc, More preferably, it is 10-70 seconds / 100cc. Incidentally, when the air permeability increases, the glossiness and the image sharpness tend to be inferior. This is because the casting method dries using a mirror drum, so the water in the coating solution is evaporated through the substrate, but if the air permeability is high, the drying is insufficient or it is heated more than necessary. It is considered that the glossiness and the image definition are inferior. In the case of a base material of less than 10 seconds / 100 cc, glossiness also tends to be lowered. This is because when the ink jet recording layer is formed, most of the adhesive in the coating liquid penetrates into the base material, and the amount of adhesive in the ink jet recording layer is reduced. As a result, the cast coating layer Even if it is provided, it is considered that the gloss and image definition tend to be inferior.

  According to the present invention, when manufacturing an inkjet recording paper by the casting method, the air-permeable base material used is based on ISO 8791/4: 1992, Parker Print Surf roughness under a pressure condition of 490 kPa, and Oken type transparent paper. It is characterized by selecting a base material that satisfies the range defined by the temperament.

  Furthermore, it is preferable to use a paper base material mainly composed of wood pulp and having an ash content of 7 to 20% as the air-permeable base material. When there is too much ash, there is a possibility that paper strength will fall, and when there is little, there exists a tendency for the air permeability of a paper substrate to worsen. Within this range, smoothness, air permeability, and paper strength are balanced, and as a result, an ink jet recording sheet having excellent glossiness and image sharpness can be easily obtained.

Furthermore, it is preferable to use a paper base material containing wood pulp as a main component and calcium carbonate as a filler as the gas-permeable base material. The use of calcium carbonate is preferable because it provides a substrate with high whiteness and increases the glossiness of the ink jet recording paper.
From the viewpoint of suitability for the casting method, the air-permeable base material should have an Oken type air permeability of about 10 to 200 seconds / 100 cc, preferably 10 to 150 seconds / 100 cc, more preferably 10 to 100 seconds / 100 cc. More preferably, it is 10 to 70 seconds / 100 cc. Incidentally, when the air permeability increases, the glossiness and the image sharpness tend to be inferior. This is because the casting method dries using a mirror drum, so the water in the coating solution is evaporated through the substrate, but if the air permeability is high, the drying is insufficient or it is heated more than necessary. It is considered that the glossiness and the image definition are inferior. In addition, if the air permeability is further increased, the operability at the time of cast finishing becomes poor. On the other hand, in the case of a base material that is less than 10 seconds / 100 cc, glossiness also tends to decrease. This is because when the ink jet recording layer is formed, most of the adhesive in the coating liquid penetrates into the base material, and the amount of adhesive in the ink jet recording layer is reduced. As a result, the cast coating layer Even if it is provided, it is considered that the gloss and image definition tend to be inferior.

"Inkjet recording layer"
In the present invention, at least one ink jet recording layer containing a pigment and an adhesive is provided on a gas-permeable substrate.

As pigments, kaolin, clay, calcined clay, silica, zinc oxide, aluminum oxide, aluminum hydroxide, calcium carbonate, satin white, aluminum silicate, aluminosilicate, alumina, colloidal silica, zeolite, synthetic zeolite, sepiolite, smectite, synthesis One or more of various publicly known pigments such as smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, styrene plastic pigment, hydrotalcite, urea resin plastic pigment, benzoguanamine plastic pigment may be used in combination. it can. Among these, it is preferable to contain amorphous silica, aluminosilicate, alumina, and zeolite having high ink absorbability as main components.
In the present invention, a fine particle pigment selected from silica, aluminosilicate, and alumina is used as a main component. Silica and aluminosilicate are preferable, and silica is more preferable.

Hereinafter, silica fine particles will be described as an example. The fine particle adjustment method such as silica used for the ink jet recording layer is not particularly limited, but for example, synthetic amorphous silica or the like that is generally commercially available (for example, the secondary particle diameter is about several microns). It can be obtained by applying a strong force by mechanical means to reduce the secondary particle size.
Examples of the mechanical means include an ultrasonic homogenizer, a pressure type homogenizer, a high-speed rotary mill, a roller mill, a container drive catalyst mill, a catalyst stirring mill, a jet mill, and a sand grinder. The silica fine particles treated in this way are generally obtained as an aqueous dispersion (slurry or colloidal particles) having a solid content concentration of about 5 to 20%.

The average particle diameter as used in the present invention is a particle diameter observed with an electron microscope (SEM and TEM) (take an electron micrograph of 10,000 to 400,000 times, measure the Martin diameter of particles in 5 cm square, Averaged, as described in “Particulate Handbook” (Asakura Shoten, P52, 1991).
The average particle diameter of fine pigments such as silica (substantially mainly secondary particles) used in the ink jet recording layer is 10 to 1000 nm, preferably 10 to 800 nm, more preferably 10 to 500 nm, and more preferably 10 It is adjusted to ˜300 nm, preferably 15 to 150 nm, most preferably 20 to 100 nm. When the average particle diameter of secondary particles such as silica exceeds 1000 nm, the transparency of the ink jet recording layer is lowered, and the color developability of the colorant fixed in the ink jet recording layer is lowered to obtain a desired print density. I can't. In addition, when silica fine particles having an extremely small average particle diameter of secondary particles are used, the ink absorbability is lowered, and there is a possibility that blurring or the like may occur, and a desired image quality may not be obtained.

  The average particle diameter of the primary particles of the fine particle pigment such as silica is preferably adjusted to 3 to 40 nm, more preferably 5 to 30 nm, still more preferably 7 to 20 nm. When the average primary particle diameter is less than 3 nm, the voids between the primary particles are remarkably reduced, the ability to absorb the solvent and colorant in the ink is lowered, and the desired image quality may not be obtained. is there. When the average primary particle diameter exceeds 40 nm, the aggregated secondary particles become large, the transparency of the ink jet recording layer is lowered, and the coloring property of the colorant fixed in the ink jet recording layer is lowered. There is a possibility that a desired print density may not be obtained.

  The ratio of fine particles such as silica in all pigments in the ink jet recording layer is desirably 50% or more in order to maintain the transparency of the ink jet recording layer. When the ratio of fine pigments such as silica fine particles in all pigments is less than 50%, there is a concern that transparency may be lowered, and image quality such as print density may be lowered.

  Examples of the adhesive used in the ink jet recording layer include water-soluble resins (for example, polyvinyl alcohols such as polyvinyl alcohol, cation-modified polyvinyl alcohol, and modified polyvinyl alcohol such as silyl-modified polyvinyl alcohol, casein, soybean protein, synthetic proteins, starch, Cellulose derivatives such as carboxymethyl cellulose and methyl cellulose), conjugated diene polymer latex such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, vinyl copolymer latex such as styrene-vinyl acetate copolymer, etc. Various other publicly known and commonly used adhesives in the field of coated paper, such as water-dispersible resins, water-based acrylic resins, water-based polyurethane resins and water-based polyester resins, are used alone or in combination. The aqueous polyurethane resin is also commonly referred to as urethane emulsion, urethane latex, polyurethane latex and the like. The polyurethane resin is obtained from a reaction between a polyisocyanate compound and an active hydrogen-containing compound. It is a polymer compound containing a relatively large number of urethane bonds and urea bonds.

  When a cationic compound is blended in the ink jet recording layer, a cationic or nonionic adhesive is preferable because the coating composition has good stability. The compounding quantity of an adhesive agent is adjusted in the range of 1-200 mass parts with respect to 100 mass parts of pigments, More preferably, it is 5-100 mass parts. Here, if the amount of the adhesive is small, the strength of the coating layer is weakened, and the surface of the cast coating layer formed thereon may be easily damaged, or powder may fall off. On the other hand, if the amount of the adhesive is large, the ink absorptivity is lowered and the desired ink jet recording suitability may not be obtained.

  Since the colorant of the inkjet ink is usually anionic, it is preferable to add a cationic compound to the inkjet recording layer for the purpose of fixing the colorant component in the ink. The blending method may be mixed with the fine particle pigment such as silica, but particularly when the fine pigment is silica fine particles, the silica fine particles are generally anionic, and aggregation of the silica fine particles occurs during mixing. There is a case.

  Therefore, when amorphous silica (having a secondary particle size of several microns) is pulverized into fine particles by applying strong force by mechanical means, the cationic compound is mixed together with the amorphous silica before pulverization. Dispersing and pulverizing by mechanical means after dispersion, or mixing a cationic compound with finely divided silica secondary particle dispersion, once thickening and aggregating, and then mechanically dispersing and pulverizing again. Therefore, it is preferable to use cationic fine silica adjusted to the specific particle size. The cationic fine silica treated in this way has a structure in which the cationic compound is partly bonded and is a slurry that is stably dispersed. It is difficult.

  Examples of the cationic compound include a cationic resin and a low molecular weight cationic compound (for example, a cationic surfactant). From the viewpoint of the effect of improving the printing density, a cationic resin is preferable, and it can be used as a water-soluble resin or an emulsion. Further, it can also be used as a cationic organic pigment in which a cationic resin is insolubilized by means of crosslinking or the like to form a particulate form. Such cationic organic pigments are obtained by copolymerizing a polyfunctional monomer to form a crosslinked resin when polymerizing a cationic resin, or reactive functional groups (hydroxyl group, carboxyl group, amino group, acetoacetyl group, etc.) If necessary, a crosslinking agent is added to a cationic resin having a crosslinking resin by means of heat, radiation or the like. Cationic compounds, particularly cationic resins, may also serve as adhesives.

The following can be illustrated as a cationic resin. In particular,
1) Polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof,
2) an acrylic resin having a secondary amine group, a tertiary amine group or a quaternary ammonium group;
3) polyvinylamine, polyvinylamidines,
4) Dicyan cationic resin represented by dicyandiamide-formalin polycondensate,
5) Polyamine cationic resin represented by dicyandiamide-diethylenetriamine polycondensate,
6) Epichlorohydrin-dimethylamine addition polymer,
7) Dimethyl diallylammonium chloride-SO ₂ copolymer,
8) diallylamine salt-SO ₂ copolymer,
9) Dimethyl diallylammonium chloride polymer,
10) Polymer of allylamine salt,
11) Dialkylaminoethyl (meth) acrylate quaternary salt polymer,
12) Cationic compounds such as acrylamide-diallylamine salt copolymer.

  The cationic compound further has an effect of improving the printed image water resistance. The cationic compound which can be mix | blended with an inkjet recording layer can be used in 1-100 mass parts with respect to 100 mass parts of pigments, More preferably, it is 5-50 mass parts. If the blending amount is small, it is difficult to obtain the effect of improving the printing density. If the blending amount is large, the printing density may be lowered, or the image may be blurred or uneven.

  In addition, when the cationic compound is blended in at least the upper ink-jet recording layer (layer close to the surface) of the ink-jet recording layer provided in two or more layers, the desired effect is often obtained. When the coating amount of the ink jet recording layer is small, it can also be blended in the lower ink jet recording layer. There are cationic compounds that are particularly effective in improving the printing density and those that are particularly effective in improving the printing water resistance. Each of them is appropriately used depending on the purpose, or several types are used in combination. be able to.

The ink jet recording layer is a blade coater, an air knife coater, a roll coater, a brush coater, a chamber coater, an undercoat layer provided on the substrate with an ink jet recording layer coating liquid, if necessary. Coating and drying are performed by various known coating apparatuses such as a bar coater, a lip coater, a gravure coater, a curtain coater, a slot die coater, and a slide coater. The coating amount of the inkjet recording layer (total) is, 1 to 50 g / ^{m 2} on a dry solids, preferably 1.5~30g / ^{m 2.} Here, if it is less than 1 g / m ² , bleeding tends to occur during printing, and if it exceeds 50 g / m ² , the print density tends to be insufficient.
When an undercoat layer is provided, a sufficient effect may be obtained at about 1 to 10 g / m ² .

“Undercoat”
In the present invention, an undercoat layer can be provided between the substrate and the inkjet recording layer for the purpose of increasing the ink absorption capacity and absorption speed, and it is preferable to form the undercoat layer. The ink jet recording layer is a layer mainly fixing a colorant, that is, a dye or a color pigment in the ink jet ink component, and the undercoat layer is a layer mainly absorbing a solvent in the ink jet ink component quickly. However, the distinction is not necessarily clear. When the amount of ink is small, the colorant may be fixed only to the ink jet recording layer. When the amount of ink increases, a part of the colorant is fixed to the undercoat layer. .

The undercoat layer contains a pigment and an adhesive as main components.
As the pigment for the undercoat layer, kaolin, clay, calcined clay, amorphous silica (also called amorphous silica), synthetic amorphous silica, zinc oxide, aluminum oxide, aluminum hydroxide, calcium carbonate, satin white, aluminum silicate , Alumina, colloidal silica, zeolite, synthetic zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, styrene plastic pigment, hydrotalcite, urea resin plastic pigment, benzoguanamine plastic pigment, etc. One or more of various publicly known pigments in the general coated paper production field can be used in combination. Among these, it is preferable to contain amorphous silica, alumina, and zeolite having high ink absorbability as main components.

  These pigments (used as a main component) have an average particle size (aggregated particle size in the case of an agglomerated pigment) of preferably about 1 to 20 μm, more preferably 2 to 10 μm, and further preferably 3 to 8 μm. If the thickness is less than 1 μm, the effect of improving the ink absorption rate is poor, and if it exceeds 20 μm, the smoothness and gloss after the cast coating layer is provided may be insufficient. However, a pigment having a small particle diameter can be blended as a subcomponent for the purpose of adjusting the ink absorbability or controlling the penetration of the coating material applied onto the undercoat layer. Examples of such pigments include colloidal silica, alumina sol, or fine silica particles contained in an ink jet recording layer described later.

  As the adhesive for the undercoat layer, polyvinyls including proteins such as casein, soy protein, synthetic protein, various starches such as starch and oxidized starch, polyvinyl alcohol, cationic polyvinyl alcohol, modified polyvinyl alcohol such as silyl modified polyvinyl alcohol Vinyls such as alcohols, cellulose derivatives such as carboxymethyl cellulose and methyl cellulose, styrene-butadiene copolymers, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, acrylic polymer latex, ethylene-vinyl acetate copolymer Conventionally known adhesives that are generally used for coated paper, such as polymer latex, are used alone or in combination.

  The blending ratio of the pigment and adhesive in the undercoat layer is generally adjusted in the range of 1 to 100 parts by weight, preferably 2 to 50 parts by weight, based on 100 parts by weight of the pigment. In addition, various auxiliary agents such as dispersants, thickeners, antifoaming agents, antistatic agents, preservatives and the like used in the production of general coated paper are appropriately added. Fluorescent dyes and colorants can also be added to the undercoat layer.

  In the undercoat layer, a cationic compound can be blended for the purpose of fixing the colorant (dye or colored pigment) component in the ink for ink jet recording. As a cationic compound, what was illustrated as a cationic compound mix | blended with an inkjet recording layer can be used suitably. However, since the ink is fixed in the ink jet recording layer rather than the undercoat layer, the recording density is higher and a clear image can be obtained. Therefore, the amount of the cationic compound in the undercoat layer is 50% or less of the ink jet recording layer, Preferably it is 20% or less. More preferably, a cationic compound is blended only in the ink jet recording layer, and the cationic compound is substantially absent in the undercoat layer. “Substantially absent” excludes the addition of a small amount of an auxiliary agent such as a cationic surfactant.

Subbing layer composition generally the solid concentration was adjusted to about 5 to 50 mass%, 2~100g / ^{m 2} by dry weight on paper substrate, preferably 5 to 50 g / ^{m 2} approximately, more preferably It is good to apply so that it may become about 5-20 g / m < ² >. If the coating amount is small, the ink absorption improvement effect may not be sufficiently obtained, or gloss may not be sufficiently obtained when a cast coating layer is provided. In some cases, the strength of the work layer is reduced, and powder falls and scratches are likely to occur.

  For the undercoat layer, the undercoat layer composition is a variety of types such as blade coaters, air knife coaters, roll coaters, brush coaters, champlex coaters, bar coaters, lip coaters, gravure coaters, curtain coaters, slot die coaters, and slide coaters. Coating and drying are performed by a publicly known coating apparatus. Furthermore, if necessary, after the undercoat layer is dried, a smoothing process such as super calendering or brushing can be performed.

"About cast coating layer"
A coating liquid containing a pigment and an adhesive is applied onto the ink jet recording layer thus formed, and the heated mirror drum is applied to the heated mirror drum while the coating liquid is in a wet or rewet state. Finished by pressure welding and drying.

  As the pigment used for the cast coating layer, a fine particle pigment selected from silica, aluminosilicate, alumina, and zeolite having an average particle diameter (in the case of an aggregate pigment, an average value of the aggregate particle diameter) of 1 μm or less is used. Silica and aluminosilicate are preferable, and silica is more preferable. The smaller the particle diameter, the better the transparency, and therefore, it is preferable because it shows gloss and does not decrease the concentration of the ink formed on the ink jet recording layer. Colloidal silica is more preferable as the fine particle pigment, and anionic colloidal silica is particularly preferable, and a true spherical one is particularly preferable.

  The cast coating layer is not a layer for fixing ink, but is a thin layer (thinner than the ink jet recording layer) formed on the ink jet recording layer in order to develop gloss, and is formed on the surface of the ink jet recording layer. It is a layer that prevents irregular reflection by eliminating fine irregularities and expresses higher gloss. Therefore, the use of fine particles is preferred, and the use of colloidal silica, which is a dispersion of primary particles of silica, is preferred. In particular, anionic colloidal silica is preferable because it is anionic and can form a cast coating layer having no ability to fix ink.

  The average particle diameter of the anionic colloidal silica is 0.01 to 0.15 μm, preferably 0.015 to 0.12 μm, and more preferably 0.02 to 0.10 μm. When the average particle size is less than 0.01 μm, the ink absorbability is lowered, and when it exceeds 0.15 μm, the glossiness and the sharpness of the color of the recorded image are lowered.

  In the cast coating layer, the exemplified pigment for the cast coating layer can be used in combination as long as the effects of the colloidal silica are not impaired.

  Examples of the adhesive used for the cast coating layer of the present invention include polyvinyl alcohols such as polyvinyl alcohol, cation-modified polyvinyl alcohol, and silyl-modified polyvinyl alcohol, casein, soy protein, synthetic proteins, starch, carboxymethylcellulose, and methylcellulose. Cellulose derivatives, vinyl acetate polymer emulsion, styrene-butadiene copolymer emulsion, ethylene-vinyl acetate copolymer emulsion, acrylic copolymer emulsion, styrene-acrylic copolymer emulsion, aqueous acrylic resin, aqueous Various adhesives commonly used in the field of coated paper, such as polyurethane resins and water-based polyester resins, are used alone or in combination.

  Among these, use of casein is preferable because it is excellent in releasability from a cast drum when forming a cast coating layer. Acrylic copolymer emulsions and styrene-acrylic copolymer emulsions are preferred because the recorded images have excellent clarity and gloss. These can also be used in combination.

When using an emulsion as the adhesive for the cast coating layer, the preferred mass average molecular weight is 1000 to 10 million, more preferably 5000 to 5 million. The strength of the cast coating layer having a low molecular weight tends to be insufficient, and the stability of the emulsion tends to be insufficient if the molecular weight is high.
The average particle size of the emulsion is preferably about 0.02 to 0.15 μm. If it is less than 0.02 μm, the ink absorption performance tends to be inferior. When it exceeds 0.15 μm, the gloss and the sharpness of the recorded image tend to be lowered.
Furthermore, the glass transition temperature of the emulsion is preferably 50 to 150 ° C. When the glass transition temperature is low, film formation of the cast coating layer at the time of drying proceeds excessively, so that the surface porosity tends to decrease and the ink absorption rate tends to decrease. When the glass transition temperature is high, the film forming property at the time of drying becomes insufficient, and the glossiness may be insufficient.

  The composition ratio (solid content mass ratio) between the pigment of the cast coating layer and the adhesive is preferably 3 to 150 parts by mass, more preferably 7 to 100 parts by mass, and more preferably 10 to 70 parts by mass with respect to 100 parts by mass of the pigment. Is more preferable. When the ratio of the adhesive exceeds 150 parts by mass, the sharpness of color development of the recorded image tends to be reduced, and when it is less than 3 parts by mass, the gloss tends to decrease.

In the cast coating layer, a mold release agent is preferably blended in order to smoothly separate the cast coating layer and the mirror drum during production.
Examples of mold release agents include higher fatty acid amides such as stearamide and oleic amide, polyolefin waxes such as polyethylene wax, polyethylene oxide wax and polypropylene wax, calcium stearate, zinc stearate, potassium oleate and ammonium oleate. Examples thereof include higher fatty acid alkali salts, silicone compounds such as lecithin, silicone oil and silicone wax, and fluorine compounds such as polytetrafluoroethylene.

  The compounding quantity of a mold release agent is 0.1-50 mass parts with respect to 100 mass parts of pigments, Preferably it is 0.3-30 mass parts, More preferably, it adjusts in the range of 0.5-20 mass parts. If the blending amount is small, the effect of improving the releasability is difficult to obtain. On the other hand, if the blending amount is large, the gloss may be lowered or the ink repellency or the recording density may be lowered.

  In the coating composition for forming the cast coating layer, pigments and erasing agents used in general printing coated paper and inkjet paper are used to adjust the whiteness, viscosity, fluidity and the like. Various auxiliary agents such as a foaming agent, a coloring agent, a fluorescent brightening agent, an antistatic agent, an antiseptic and a dispersing agent, and a thickening agent are appropriately added.

  When coating the coating liquid for the cast coating layer on the inkjet recording layer, blade coater, air knife coater, roll coater, brush coater, champlex coater, bar coater, lip coater, gravure coater, curtain coater, slot die coater Various known coating apparatuses such as a coater and a slide coater can be used. In the present invention, the cast coating layer is a cast coating layer formed by a casting method. The casting method is a method for obtaining a smooth and glossy coating layer surface by drying the coating layer on a mirror drum (cast drum) having smoothness and copying the smooth surface onto the coating layer. is there.

  As a method of providing a cast coating layer using a mirror drum, the above-mentioned cast coating layer coating solution was applied onto an ink jet recording layer and heated while the coating layer was in a wet state. A method of press-contacting and drying on a mirror drum (wet casting method), a method of drying the coating layer once and then re-wetting, and pressing and drying a heated mirror drum (dry coating method), Examples thereof include a method (solidification cast method) in which the construction layer is solidified into a deformable gel state that does not have fluidity, and is pressed against a heated mirror drum and dried. Alternatively, a method (precast method) in which a coating liquid for a cast coating layer is directly applied to a heated mirror drum and then pressed and dried on the lower surface of the inkjet recording layer on the substrate side can be employed.

  The surface temperature of the mirror drum is preferably about 40 to 200 ° C, more preferably 70 to 150 ° C. If it is lower than 40 ° C., it takes time to dry, film formation tends to be insufficient, and gloss is lowered. If the temperature is higher than 200 ° C., the film formation proceeds excessively, the surface porosity decreases, the ink absorption rate decreases, but the paper surface may become rough or the gloss may decrease.

When the coating liquid for the cast coating layer is applied onto the inkjet recording layer and finished by pressing and drying on a heated mirror drum while the inkjet recording layer and the cast coating layer are in a wet state, For the purpose of suppressing penetration of the coating liquid for layer coating into the ink jet recording layer, a method of promoting immobilization of the coating liquid for cast coating layer can also be adopted.
As this method, for example, (1) a gelling agent that promotes immobilization of the coating liquid for the cast coating layer is blended in the inkjet recording layer, and (2) the cast coating is applied on the inkjet recording layer. Apply and impregnate a gelling agent that promotes immobilization of the coating solution for the layer. (3) After applying the coating solution for the cast coating layer, the immobilization of the coating solution for the cast coating layer (4) Gelling agent that promotes immobilization in the process of drying the coating liquid in the coating liquid for cast coating layer. May be included.

  Examples of such a gelling agent include boric acid, formic acid and the like, and salts thereof, aldehyde compounds, epoxy compounds, and the like, which are crosslinking agents for adhesives in the coating liquid for cast coating layers. Of the above methods, when the wet casting method is adopted, it is better to apply the cast coating layer coating liquid on the ink receiving layer, press the pressure on the mirror drum and dry it as much as possible. Since the penetration of the coating liquid is suppressed, gloss is easily developed. Furthermore, immediately before the ink receiving layer surface is pressed against the drum, a cast coating layer coating solution is applied between the ink receiving layer surface on the pressing roll (press roll) and the mirror drum and immediately pressed (nip cast method). However, the penetration of the coating liquid is suppressed as much as possible, and good gloss and print quality can be easily obtained with a small coating amount, which is particularly preferable.

The coating amount of the cast coated layer, 0.1 to 20 g / ^{m 2} approximately on a dry solids, preferably 0.2 to 10 g / ^{m 2,} more preferably 0.5 to 5 g / ^{m 2.} Here, if it is less than 0.1 g / m ^2, it is difficult to obtain sufficient gloss, and if it exceeds 20 g / m ² , bleeding tends to occur during printing or the print density tends to be insufficient. After providing by cast finishing, a smoothing process can also be performed using a super calendar or the like.
The 75 ° glossiness (JIS-P-8142) on the surface of the surface layer is preferably 60% or more, more preferably 65% or more, and still more preferably 70% or more, in order to impart the texture of photographic paper.

  The cast ink jet recording paper finished in this way preferably has a 20 ° glossiness of 35% or more on the surface of the cast coating layer according to JIS-Z-8741. Moreover, it is preferable that the image sharpness measured at an angle of 60 ° is 55% or more in accordance with JIS-K-7105. Furthermore, the Oken type air permeability is preferably 60 to 200 seconds / 100 cc. Moreover, it is preferable that the Parker Print Surf roughness on the surface of the cast coating layer is 4 μm or less in accordance with ISO 8791/4: 1992 under a pressure condition of 490 kPa.

  In the present invention, it is preferable to provide an undercoat layer having a pigment and an adhesive on an air-permeable substrate, and to form an ink jet recording layer and a cast coating layer on the undercoat layer. Especially, it is preferable that the pigment of an undercoat layer is a silica with an average particle diameter of 1-20 micrometers. Furthermore, it is preferable that the undercoat layer does not have a cationic compound. The ink jet recording layer is a layer mainly fixing a colorant, that is, a dye or a color pigment in the ink jet ink component, and the undercoat layer is a layer mainly absorbing a solvent in the ink jet ink component quickly. When such an undercoat layer is employed, the ink solvent penetrates into the ink jet recording layer and the undercoat layer, but since the dye remains in the ink jet recording layer, high-density recording can be performed.

  Further, the present invention provides a pigment which is a secondary particle having an average primary particle diameter of 3 to 40 nm and an average secondary particle diameter of 10 to 1000 nm selected from the group consisting of silica, aluminosilicate and alumina. It is preferable to form an ink jet recording layer having Among these, it is preferable to contain at least one kind of cationic fine silica as a pigment. Moreover, it is preferable that the inkjet recording layer contains a cationic compound. When such an ink jet recording layer is employed, the gloss is excellent, and the recording density and ink absorbability are excellent.

  Furthermore, in the present invention, it is preferable to form a cast coating layer using colloidal silica as a pigment. Among these, it is more preferable to contain anionic colloidal silica. Such a cast coating layer is not a layer for fixing ink, but a thin layer (thinner than the ink jet recording layer) formed on the ink jet recording layer in order to develop gloss. Colloidal silica is a dispersion of primary particles of silica, and the cast coating layer containing this as the main component can eliminate fine irregularities on the surface of the ink jet recording layer, thereby preventing irregular reflection and higher gloss. Sex can be expressed. The use of a perfectly spherical colloidal silica having a uniform shape is preferred for gloss. In particular, since anionic colloidal silica is anionic, a cast coating layer having no ability to fix ink can be formed, which is preferable.

  The cast coating layer is prepared by applying a coating solution for a cast coating layer containing a pigment and an adhesive onto an inkjet recording layer, and while in a wet state, press and dry against a heated mirror drum to finish the casting. However, it is preferable to form the cast coating layer by applying the coating liquid for cast coating layer and immediately contacting the mirror drum.

  Furthermore, it is preferable that the surface of the cast coating layer is manufactured so as to have a Parker print surf roughness of 4 μm or less under a pressure condition of 490 kPa, in accordance with ISO 8791/4: 1992.

  Such a cast type ink jet recording sheet may be subjected to an adhesive process on the back surface. Further, recording paper (for example, ink jet recording paper, thermal recording paper, thermal transfer recording image receiving paper, magnetic recording paper, etc.) may be laminated on the back surface. Another substrate (paper, film, non-woven fabric, magnetic card, IC card, etc.) or the like may be bonded to the other surface.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Moreover, unless otherwise indicated, the part and% in an example show a mass part and mass%, respectively.

Example 1
“Production of air-permeable substrate (paper substrate)”
Wood pulp (LBKP: freeness of 440 ml CSF) 100 parts, filler (calcium carbonate 3: talc 1 ratio) 15 parts, commercially available sizing agent 0.04 parts, sulfate band 0.45 parts, starch 1.00 parts, yield Using a papermaking material consisting of a little improver, a paper substrate having a basis weight of 170 g / m ² was obtained with a long paper machine, and then subjected to a super calender treatment at a linear pressure of 100 kg / cm.
The resulting paper substrate had a thickness of 195 μm.

"Preparation of silica sol"
Commercially available vapor phase silica (trade name: Leolosil QS-30, average primary particle size 9 nm, specific surface area 300 m ² / g, manufactured by Tokuyama Corporation) was dispersed and pulverized with a sand grinder, then nanomizer (trade name: nanomizer, Using a nanomizer), pulverization and dispersion were repeated, and after classification, a 10% dispersion having an average secondary particle diameter of 80 nm was prepared.
10 parts of diallyldimethylammonium chloride-acrylamide copolymer (trade name: PAS-J-81, manufactured by Nitto Boseki Co., Ltd.) is added as a cationic compound to the dispersion to agglomerate the pigment and increase the dispersion. After causing viscosity, pulverization and dispersion were repeated using a nanomizer again to prepare an 8% dispersion having an average secondary particle size of 300 nm to obtain a silica sol.

"Formation of undercoat layer"
On the paper base material, the following undercoat layer coating solution was applied and dried with an air knife coater so that the dry mass was 9 g / m ² .

[Coating liquid for undercoat layer]
Synthetic amorphous silica (trade name: Fine Seal X-30, manufactured by Tokuyama Corporation, average secondary particle size 3.2 μm) 100 parts, silyl-modified polyvinyl alcohol (trade name: R1115, manufactured by Kuraray Co., Ltd.) 20 Parts, polyvinyl alcohol (trade name: PVA145, Kuraray Co., Ltd. 5 parts, fluorescent dye (trade name: WhitetexBPSH, Sumitomo Chemical Co., Ltd.) 2 parts, cationic compound (trade name: Unisense CP104) 3 parts.

"Formation of inkjet recording layer and cast coating layer"
Next, an air knife coater and a cast coating apparatus having a drying apparatus are used. First, an air knife coater is applied so that the following coating liquid for an inkjet recording layer is 4 g / m ² on the obtained undercoat layer. And dried with a drying apparatus. Subsequently, the following coating solution for cast coating layer was applied, and while being in a wet state, it was pressed against a heated mirror drum and dried to obtain an inkjet recording paper. The coating amount of the cast coating layer at this time was ² g / m ² in terms of dry mass.

[Coating liquid for inkjet recording layer]
100 parts of the above silica sol, 10 parts of polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray Co., Ltd.).

[Cast coating layer coating solution]
Composite emulsion of acrylic emulsion and glass colloidal silica having a glass transition point of 100 ° C. (trade name: Aquabrid 906, manufactured by Daicel Chemical Industries, Ltd., acrylic emulsion and colloidal silica are 20:80 by mass ratio, and the particle size of the emulsion is 40 nm) 100 parts, casein 5 parts, thickener 6 parts, release agent (stearic acid) 5 parts.

Example 2
A paper base material and an ink jet recording paper were obtained in the same manner as in Example 1 except that in the production of the air-permeable base material (paper base material) of Example 1, the filler was changed to 5 parts.

Comparative Example 1
A paper base material and an inkjet recording paper were obtained in the same manner as in Example 1 except that the following air-permeable base material (paper base material) was used.

“Production of air-permeable substrate (paper substrate)”
A papermaking material consisting of 100 parts of wood pulp (LBKP: freeness 400 mlCSF), 0 parts of filler, 0.04 part of commercial sizing agent, 1 part of sulfuric acid band, 0.5 part of starch, and a little yield improver is used. After obtaining a paper substrate having a basis weight of 210 g / m ^{2 using} a net paper machine, a super calender treatment was performed at a linear pressure of 150 kg / cm.
The resulting paper substrate had a thickness of 195 μm.

Comparative Example 2
On the paper base material used in Example 1, the following coating liquid for inkjet recording layer was coated and dried with an air knife coater so that the dry mass was 13 g / m ² . Further, the following coating solution for cast coating layer was applied, and while in a wet state, it was pressed against a heated mirror drum and dried to obtain an ink jet recording paper.

[Coating liquid for inkjet recording layer]
Synthetic amorphous silica (trade name: Fine Seal X-30, manufactured by Tokuyama Corporation, average secondary particle size 3.2 μm) 100 parts, silyl-modified polyvinyl alcohol (trade name: R1115, manufactured by Kuraray Co., Ltd.) 20 Parts, polyvinyl alcohol (trade name: PVA145, Kuraray Co., Ltd. 5 parts, fluorescent dye (trade name: WhitetexBPSH, Sumitomo Chemical Co., Ltd.) 2 parts, cationic compound (trade name: Unisense CP104) 3 parts.

[Cast coating layer coating solution]
Composite emulsion of acrylic emulsion and glass colloidal silica having a glass transition point of 100 ° C. (trade name: Aquabrid 906, manufactured by Daicel Chemical Industries, Ltd., acrylic emulsion and colloidal silica are 20:80 by mass ratio, and the particle size of the emulsion is 40 nm) 100 parts, casein 5 parts, thickener 6 parts, release agent (stearic acid) 5 parts.

Comparative Example 3
A paper base material and an inkjet recording paper were obtained in the same manner as in Example 1 except that the following air-permeable base material (paper base material) was used.

“Production of air-permeable substrate (paper substrate)”
100 parts of wood pulp (LBKP: freeness of 420 ml CSF), 4 parts of calcined kaolin (trade name: Ansilex, Engelhard) as filler, 0.04 part of commercial sizing agent, 2 parts of sulfuric acid band, 1.00 parts of starch Using a papermaking material consisting of a small amount of yield improver, a paper substrate having a basis weight of 150 g / m ² was obtained with a long net paper machine, and then subjected to supercalender treatment at a linear pressure of 100 kg / cm.
The resulting paper substrate had a thickness of 195 μm.

Comparative Example 4
A paper base material and an inkjet recording paper were obtained in the same manner as in Example 1 except that the following air-permeable base material (paper base material) was used.

“Production of air-permeable substrate (paper substrate)”
A papermaking material consisting of 100 parts of wood pulp (LBKP: freeness 420 ml CSF), 0 part of filler, 0.04 part of commercial sizing agent, 3 parts of sulfuric acid band, 1.00 part of starch and a little yield improver is used. After obtaining a paper substrate having a basis weight of 210 g / m ^{2 using} a net paper machine, a super calender treatment was performed at a linear pressure of 150 kg / cm.
The resulting paper substrate had a thickness of 195 μm.

Comparative Example 5
Using the paper base material used in Comparative Example 3, an ink jet recording layer and a cast coating layer were provided in the same manner as in Comparative Example 2 to obtain an ink jet recording paper.

Table 1 shows the roughness, air permeability, Steecht sizing degree, and ash content of the paper base used in each Example and Comparative Example. These test methods are as shown below.
[Roughness]
Based on ISO 8791/4: 1992, the pressure was measured with a Parker Print Surf roughness meter under a pressure condition of 490 kPa. The larger the value, the rougher it becomes.
[Air permeability]
Measured with a Oken air permeability meter.

[Stick human sizing degree]
It measured by the method of JIS-P-8122.
〔ash〕
It measured by the method of JIS-P-8204.

Table 1 shows the white paper gloss, image definition, roughness, and air permeability of the ink jet recording paper obtained in each example and comparative example. These test methods are as shown below.
[Glossiness]
According to JIS-Z-8741, 20 ° gloss and 75 ° gloss of the white paper portion were measured.
(Image clarity)
The image definition at 60 degrees reflection was measured based on JIS-K-7105 using an image definition measuring device ICM-IDP manufactured by Suga Test Instruments Co., Ltd.

[Roughness]
Based on ISO 8791/4: 1992, the pressure was measured with a Parker Print Surf roughness meter under a pressure condition of 490 kPa. The larger the value, the rougher it becomes.
[Air permeability]
Measured with a Oken air permeability meter.

The inkjet recording suitability of the inkjet recording paper obtained in each example and comparative example was evaluated according to the following criteria, and the results are shown in Table 1.
[Print bleeding]
Printing was performed using an inkjet printer BJS700 (manufactured by Canon Inc.), and bleeding of the printing was evaluated.
(Double-circle): The blur of printing is not recognized at all and it is an excellent level.
○: Slight bleeding is observed but good level.
Δ: Slightly blurring of printing and slightly problematic in practical use.
X: The level at which printing blur is remarkable and becomes a serious problem in practical use.

[Ink dryness]
Printing was performed using an ink jet printer PM950C (manufactured by Epson Corporation).
The dryness of the ink was evaluated for a solid print portion of two colors of cyan ink and magenta ink.
○: Even if it is touched with a finger immediately after printing, it is not soiled at all.
Δ: Slightly dirty when touched with a finger immediately after printing.
X: When touched with a finger immediately after printing, it becomes dirty.

[Uniformity of solid print area]
Printing was performed using an ink jet printer PM950C (manufactured by Epson Corporation).
The printing unevenness (dark shading unevenness) of the solid printing portion of two colors mixed of cyan ink and magenta ink was visually evaluated.
A: Excellent printing level with no printing unevenness.
○: Print unevenness is slightly observed, but a good level.
Δ: Slight printing unevenness, which is a slightly problematic level for practical use.
X: Level of printing unevenness and problematic in practical use.

[Print density after inkjet recording]
Printing was performed using an ink jet printer PM950C (manufactured by Epson Corporation).
The print density of the black solid print portion was measured with Macbeth RD-914.

[Visual appearance]
The glossiness and smoothness were visually evaluated.
A: Extremely excellent.
○: Excellent.
Δ: Slightly inferior
X: Inferior.

〔Comprehensive evaluation〕
Overall evaluation.
5: Extremely excellent.
4: Excellent.
3: Normal.
2: Slightly inferior.
1: Inferior.

Claims (4)

An at least one ink jet recording layer containing a pigment and an adhesive is provided on a gas-permeable substrate, and a coating liquid containing the pigment and the adhesive is applied on the ink jet recording layer. In a method for producing an ink jet recording paper in which a cast coating layer is formed by press contact with a heated mirror drum while being wet or rewet, and forming a cast coating layer, the main component is wood pulp, In addition, a paper base having an ash content of 1 to 20% is used, and the surface on which the cast coating layer is provided conforms to ISO 8791/4: 1992, and the Parker print surf roughness at a pressure condition of 490 kPa is 6 μm or less. And a method for producing an ink jet recording paper, comprising using a paper base material having Oken type air permeability of 10 to 200 seconds / 100 cc. The method for producing an ink jet recording paper according to claim 1, wherein the air-permeable base material is a paper base material containing wood pulp as a main component and having an ash content of 7 to 20%. The pigment of the inkjet recording layer is secondary particles having an average primary particle diameter of 3 to 40 nm and an average secondary particle diameter of 10 to 1000 nm selected from the group consisting of silica, aluminosilicate, and alumina. The method for producing an inkjet recording paper according to claim 1 or 2. The manufacturing method of the inkjet recording paper in any one of Claims 1-3 in which the pigment of an inkjet recording layer contains at least 1 sort (s) of cationic fine silica.