JP2000289325A - Ink jet recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording sheet having excellent gloss of particularly on a white portion and a printed portion, excellent surface strength of the white portion without lowering the gloss in a later step, and excellent printing density, ink absorbency, ink jet recording suitability of recording image quality or the like. SOLUTION: The ink jet recording sheet comprises a gloss layer containing a pigment and an adhesive in a base material. In this case, the layer contains a cellulose derivative having a carboxyalkyl group and a nitric ester group in a substituent, and the pigment of the layer has a mean particle size of 500 nm or below. As the pigment, silica fine particles having a mean particle size of 3 to 40 nm of primary particles and a mean particle size of 10 to 400 nm of secondary particles are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording sheet, and more particularly to an ink jet recording sheet which is excellent in glossiness of a blank portion and a printed portion, surface strength of a blank portion, and ink jet recording suitability.

[0002]

2. Description of the Related Art Recording by an ink jet printer is as follows.
It is used in various fields because of low noise, high-speed recording, and easy multicoloring. As the ink jet recording paper, high quality paper devised to be rich in ink absorbency, coated paper having a surface coated with a porous pigment, or the like is applied. By the way, all of these papers are mainly so-called matte ink jet recording papers having low surface gloss, and therefore, there is a demand for ink jet recording papers having high surface gloss and excellent appearance. In general,
As a paper with a high surface gloss, a high-gloss coated paper coated with a plate-like pigment on the surface and then subjected to a calender treatment as necessary, or a wet coating layer is applied to a heated drum surface having a mirror surface A so-called cast coated paper obtained by copying the mirror surface by pressing and drying is known. This cast coated paper has higher surface gloss and better surface smoothness compared to ordinary super calendered coated paper, and provides excellent printing effect. However, when it is used for ink jet recording paper, it has various difficulties. That is, a conventional cast coated paper is generally disclosed in, for example, US Pat. No. 5,275,846. A film-forming substance such as an adhesive in the pigment composition constituting the coating layer transfers the mirror surface drum surface of the cast coater to obtain high gloss. On the other hand, there is a problem that the porosity of the coating layer is lost due to the presence of the film-forming substance, and the absorption of ink during ink jet recording is extremely reduced. In order to improve the ink absorbency, it is important that the cast coating layer is made porous so that the ink can be easily absorbed. For that purpose, it is necessary to reduce the film forming property. Reducing the amount of film-forming material results in a reduction in blank gloss. As described above, it was extremely difficult to simultaneously satisfy both the surface gloss of the cast coated paper and the suitability for inkjet recording.

As a method for solving the above problem, 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 an undercoat layer containing a pigment and an adhesive as main components. Coating a coating liquid containing a copolymer as a main component to form a coating layer for casting,
The present inventors have found that a cast paper for ink jet recording having both excellent gloss and ink absorbability can be obtained by pressing and drying to finish the mirror surface drum heated while the coating layer for casting is in a wet state. And the like are proposed in Japanese Patent Application Laid-Open No. 7-89220. Further, the present inventors have
By using ultrafine silica secondary particles having a specific particle size for the cast coating layer, it was found that gloss and extremely excellent print quality could be obtained, and this was proposed as Japanese Patent Application No. 9-132021.

[0004] The above technology has made it possible to obtain gloss and extremely excellent print quality. However, in order to have high ink absorption, a porous pigment is contained in a coating film on a base material, and as a result, the surface of The strength was reduced, causing various problems. For example, since the glossy paper surface is damaged by a paper pick-up roll or the like installed in the transport unit of the inkjet printer, even if a high-quality inkjet recorded image is obtained, the image quality is reduced as a result. In addition, the glossiness once obtained is reduced by various post-processes (printing, cutting, etc.) after the gloss processing, which causes a reduction in print image quality.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. In particular, the gloss of the blank portion and the printed portion and the surface strength of the blank portion are excellent. Provided is an ink jet recording sheet having excellent ink jet recording suitability such as absorbability and recording image quality.

[0006]

The present invention includes the following aspects. [1] In an ink jet recording paper provided with a gloss layer containing a pigment and an adhesive on a substrate, the gloss layer contains a cellulose derivative having a carboxyalkyl group and a nitrate group as a substituent, and the pigment in the gloss layer Has an average particle size of 50
An ink jet recording paper containing a pigment of 0 nm or less. [2] At least one undercoat layer containing a pigment and an adhesive is provided between the substrate and the glossy layer, and the average particle size in the glossy layer is 50.
The average particle diameter of the primary particles is 0 nm or less and the primary particles are 3 nm or more and 40 n or more.
m, and are fine silica particles having an average secondary particle diameter of 10 nm or more and 400 nm or less. [3] The inkjet recording paper according to [1] or [2], wherein the glossy layer is formed by a cast method. [4] The inkjet recording paper according to [1], wherein the carboxyalkyl group is a carboxymethyl group. [5] An ink jet recording paper having a substrate provided with a coating layer containing a cellulose derivative having a carboxyalkyl group and a nitrate ester group.

[6] In the ink jet recording paper, at least one undercoat layer containing a pigment and an adhesive is provided on a substrate, and a gloss layer containing a pigment and an adhesive is further provided on the undercoat layer. Inside, contains a cellulose derivative having a carboxylmethyl group and a nitrate group as a substituent, and the pigment in the gloss layer has an average primary particle diameter of primary particles.
3 nm or more and 40 nm or less, and the average particle diameter of the secondary particles is 10 nm or more 4
Ink jet recording paper containing silica fine particles of not more than 00 nm. [7] The inkjet recording paper according to any one of the above, wherein the glossy layer contains 0.1 to 30 parts by weight of the cellulose derivative based on 100 parts by weight of the pigment. [8] The inkjet recording paper according to [6], wherein the glossy layer is formed by a cast method. [9] At least one undercoat layer containing a pigment and an adhesive is provided on the substrate, and then a coating liquid for a cast coating layer is applied and semi-dried, and then pressed against a heated mirror-surface drum and dried. A method for producing the ink jet recording paper according to any one of the above, characterized by finishing. [10] The semi-dried coating liquid for the cast coating layer has a solid content of 1
Contains 20 to 400 parts by weight of water with respect to 00 parts by weight [9]
Manufacturing method. [11] The inkjet recording paper according to any one of [1] to [8], wherein the glossy layer further contains a cationic compound.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies on the glossy layer composition, the present inventors have found that a silica fine particle having a specific particle size is preferably provided on a substrate provided with an undercoat layer containing a pigment and an adhesive. By providing a gloss layer containing pigments such as particles and a cellulose derivative having a specific substituent, the desired glossiness of the white paper portion and the printing portion of the present invention, excellent surface strength of the white paper portion, and excellent inkjet recording suitability It was found that an ink jet recording paper was obtained, and the present invention was completed. That is, in the present invention, the specific pigment has a particle size of 500 nm or less (in the case of an agglomerated particle size, an agglomerated particle size), whereby an ink jet recording paper excellent in smoothness and glossiness can be obtained. it can.

Examples of the pigment include various kinds of pigments such as amorphous silica, aluminosilicate, and alumina, but silica is preferred in terms of transparency and gloss. In particular, the preferred average particle size of the silica fine particles (substantially mainly of secondary particles) is 10 nm or more and 400 nm or less, more preferably 15 nm or more and 150 nm or less, and most preferably 20 nm or less.
It is adjusted to at least m and at most 100 nm. If the average particle size of the secondary particles of the pigment is large, the transparency of the coating layer is reduced, and the coloring property of the dye fixed in the coating layer is reduced, so that a desired print density cannot be obtained. In addition, when a pigment having an extremely small average particle diameter of the secondary particles is used, the ink absorbency decreases, and a desired image quality cannot be obtained. Taking silica as an example, the average particle size of the primary silica fine particles is preferably adjusted to 3 nm or more and 40 nm or less, more preferably 5 nm or more and 30 nm or less, and most preferably 7 nm or less.
Not less than 20 nm. If this primary particle diameter is small,
The voids between the secondary particles become small, the ability to absorb the solvent and the dye in the ink is reduced, and the desired image quality may not be obtained. The average primary particle diameter is 40
If it exceeds nm, the aggregated secondary particles become large, the transparency of the coating layer is reduced, the coloring property of the dye fixed in the coating layer is reduced, and a desired print density may not be obtained. There is. Next, the cellulose derivative (shown by the following structural formula 1) contained in the gloss layer will be described.

[0010]

Embedded image

(Carboxymethyl group substitution degree = 1.0,
Model of substitution degree of nitrate ester = 1.0) A cellulose derivative having a specific substituent is obtained by introducing a nitrate ester group and a carboxymethyl group into a hydroxyl group of a cellulose skeleton. As a reagent,
Nitric acid, nitric acid-sulfuric acid, nitric acid-phosphoric acid, nitric acid-acetic acid mixed acid,
Examples of the method for carboxymethylation include nitrogen oxides. Examples of the method include a reaction in which monochloroacetic acid is reacted with alkali cellulose, a reaction in which cellulose is immersed in monochloroacetic acid, and then a caustic soda solution is added.

The degree of substitution is not particularly limited, but is about 0.8 to 2.2 for a nitrate ester group and about 0.2 to 1.0 for a carboxyalkyl group such as a carboxymethyl group. Here, the degree of substitution indicates the average number of substituted hydroxyl groups among all 3.0 hydroxyl groups in the anhydrous glucose residue. When the above-mentioned cellulose derivative is contained in the gloss layer, it is not clear why the surface strength is improved.However, due to the presence of the above-mentioned cellulose derivative, the solid content in the initial stage of the drying process after the application of the gloss layer coating liquid is reduced. It is considered that when the concentration becomes high, the fluidity of the coating layer is rapidly reduced and the migration of the binder is suppressed, so that the surface strength is improved. This phenomenon is particularly remarkable and effective when the coating liquid for a gloss layer contains a cationic compound.

The cellulose derivative incorporated in the glossy layer is based on 100 parts by weight of a pigment, preferably silica fine particles.
0.5 to 30 parts by weight is preferred, and more preferably 1 to 30 parts by weight.
10 parts by weight. When the amount is less than 0.5 part by weight, the effect of improving the surface strength is poor, and when the amount exceeds 30 parts by weight, the gloss and the ink absorbency are reduced, and the production efficiency is reduced due to excessive thickening of the gloss layer paint. Such a problem arises.

Further, the following resin can be contained in the gloss layer. Water-soluble resins (for example, modified polyvinyl alcohol such as polyvinyl alcohol, cation-modified polyvinyl alcohol, and silyl-modified polyvinyl alcohol, polyvinylpyrrolidone, casein, soybean protein, synthetic proteins, starch, cellulose derivatives such as carboxymethylcellulose and methylcellulose), styrene-butadiene Copolymers, conjugated diene-based polymer latex such as methyl methacrylate-butadiene copolymer, water-dispersible resin such as vinyl-based copolymer latex such as styrene-vinyl acetate copolymer, aqueous acrylic resin, aqueous polyester resin, Various adhesives known and used in the field of coated paper, such as an aqueous polyurethane resin, can be blended as long as the effects of the present invention are not impaired.

In the casting method using a heating mirror drum, it is desired that the above film-forming resin has a higher glass transition point. When the glass transition point is low, film formation proceeds excessively during drying, and the porosity of the surface is reduced. As a result, the ink absorption rate may be reduced. In addition, the drying temperature is important. If the drying temperature is too high, the film formation proceeds too much, and the porosity of the surface is reduced. As a result, the ink absorption rate decreases, and if the drying temperature is too low, the gloss is poor. And the productivity also decreases. When a pigment such as the above-mentioned silica fine particles is used in the gloss layer, the gloss layer is excellent in ink absorption and transparency.When a cationic compound is added to the gloss layer, the ink dye is efficiently fixed to the gloss layer. In combination with the transparency of the gloss layer, the print density becomes extremely excellent.

Examples of the cationic compound include a cationic resin and a low molecular weight cationic compound (for example, a cationic surfactant). A cationic resin is preferred from the viewpoint of improving the print density, and can be used as a water-soluble resin or an emulsion. Further, it can be used as a cationic organic pigment in which the cationic resin is insolubilized by means of crosslinking or the like to form a particulate form. When polymerizing a cationic resin, such a cationic pigment is used as a crosslinked resin by copolymerizing a polyfunctional monomer, or a reactive functional group (hydroxyl group, carboxyl group, amino group, acetoacetyl group, etc.)
A crosslinking agent is added to the cationic resin having
It is made into a crosslinked resin by means of heat, radiation or the like.
Cationic compounds, especially cationic resins, may also serve as adhesives.

The following are examples of the cationic resin. Specifically, 1) polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, 2) acrylic resin having a secondary amine group, tertiary amine group, or quaternary ammonium group, 3)
Polyvinylamine, polyvinylamidines, 4) dicyan cation resin represented by dicyandiamide-formalin polycondensate, 5) polyamine cation resin represented by dicyandiamide-diethylenetriamine polycondensate, 6) epichlorohydrin-dimethylamine addition polymer , 7) dimethyldiallylammonium chloride-S
0 ₂ copolymer, 8) diallylamine salt -S0 ₂ copolymer, 9) dimethyldiallylammonium chloride polymer, 10) polymers of allylamine salts, 11) dialkylaminoethyl (meth) acrylate quaternary salt polymer, 1
2) Cationic compounds such as acrylamide-diallylamine salt copolymer. The cationic compound can be used in an amount of 1 to 100 parts by weight, more preferably 5 to 50 parts by weight, based on 100 parts by weight of the pigment. If the compounding amount is small, it is difficult to obtain the effect of improving the printing density, and if it is too large, the printing density may be reduced or the image may be blurred.
Pigment, antifoaming agent, colorant, antistatic used in general printing coated paper and inkjet paper to adjust whiteness, viscosity, fluidity, etc. in the coating composition for gloss layer Various auxiliaries such as preservatives, preservatives and dispersants can be added as appropriate.

When the optical layer is provided by a cast drum described later, a release agent can be added for the purpose of imparting releasability from the cast drum. Next, the base material used in the present invention will be described. The substrate is not particularly limited, and acid paper or neutral paper used for general coated paper is appropriately used. In addition, air-permeable resin sheets and the like can also be used. The paper base is composed mainly of wood pulp and, if necessary, pigment. As the wood pulp, various chemical pulp, mechanical pulp, regenerated pulp and the like can be used, and the degree of beating of these pulp can be adjusted by a beating machine in order to adjust paper strength, suitability for papermaking, and the like. Although the degree of freeness (freeness) of the pulp is not particularly limited, it is generally 250 to 550 ml (CSF: JISP
−8121). The pigment is blended for the purpose of imparting opacity or the like or adjusting the ink absorbency, and calcium carbonate, calcined kaolin, silica, zeolite, titanium oxide and the like can be used. In this case, the amount is preferably about 1 to 20%. If it is too large, the paper strength may be reduced. As auxiliaries, a sizing agent, a fixing agent, a paper strength enhancer, a cationizing agent, a retention enhancer, a dye, a fluorescent whitening agent and the like can be added. Further, in the size press step of the paper machine, starch, polyvinyl alcohols, cationic resins and the like can be applied and impregnated to adjust the surface strength, sizing degree, and the like. The size is preferably about 1 to 200 seconds. If the degree of size is low, there may be a problem in operation such as wrinkles during coating, and if it is high, curl or cockling after printing may be remarkable due to reduced ink absorbency. The basis weight of the paper substrate is not particularly limited, but is 20 to 400 g / m ^2.
It is about.

The gloss layer can be provided directly on the substrate, but it is also possible to provide an undercoat layer on the substrate and provide a gloss layer thereon. Thereby, the ink absorbency can be increased. The undercoat layer provided on the substrate is mainly composed of a pigment and an adhesive. Pigments in the undercoat layer include kaolin, clay, calcined clay, amorphous silica (amorphous silica), zinc oxide, aluminum oxide, aluminum hydroxide, calcium carbonate, satin white, aluminum silicate, alumina, colloidal silica, zeolite, Known in the general coated paper manufacturing field, such as 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 publicly-used pigments may be used in combination. Among these, it is preferable to use amorphous silica, alumina, and zeolite having high ink absorbability as main components.

Examples of the undercoat layer adhesive (resin) include proteins such as casein, soybean protein and synthetic protein, various starches such as starch and oxidized starch, polyvinyl alcohol, cellulose derivatives such as carboxymethylcellulose and methylcellulose, and styrene-butadiene. Copolymer, methyl methacrylate-butadiene copolymer conjugated diene-based polymer latex, acrylic polymer latex, vinyl-based polymer latex such as ethylene-vinyl acetate copolymer, etc., generally used for coated paper Conventionally known adhesives may be used alone or in combination. The mixing ratio of the pigment and the adhesive depends on the type thereof, but is generally adjusted in the range of 1 to 100 parts by weight, preferably 2 to 50 parts by weight of the adhesive with respect to 100 parts by weight of the pigment. In addition, various auxiliaries such as a dispersant, a thickener, an antifoaming agent, an antistatic agent, and a preservative used in the production of general coated paper are appropriately added. A fluorescent dye and a colorant can be added to the undercoat layer.

The undercoat layer may contain a cationic compound for the purpose of fixing the dye component in the ink for ink jet recording. However, as described later, it is preferable to fix the ink dye to the gloss layer provided on the undercoat layer as much as possible, since the printing (recording) density becomes higher. It is preferable to mix a large amount of a cationic compound with the phenol. More preferably, a cationic compound is blended only in the glossy layer, and the undercoat layer is substantially free of the cationic compound. The term “substantially absent” excludes the addition of a small amount of a cationic surfactant or the like as an auxiliary agent. When a cationic compound is blended only in the gloss layer and the undercoat layer is substantially free of the cationic compound, gloss when the gloss layer is provided is most easily developed.

When the undercoat layer contains a composite of colloidal silica and a polymer resin obtained by polymerizing a monomer having an ethylenically unsaturated bond, the gloss of the outermost layer is further improved. Although the reason for this is not specifically known, it is presumed that the presence of the composite suppresses penetration of the undercoat layer into the undercoat layer while maintaining the ink absorbency of the undercoat layer. You. Examples of the polymer resin obtained by polymerizing a monomer having an ethylenically unsaturated bond include those having an alkyl group carbon number such as methyl acrylate, ethyl acrylate butyl acrylate, 2 ethylhexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, and glycidyl acrylate. 1 to 18 acrylates, methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate and the like having 1 to 18 alkyl group carbon atoms, methacrylate, styrene, α-methyl Styrene, vinyl toluene, acrylonitrile, vinyl chloride,
Examples include polymers obtained by polymerizing ethylenic monomers such as vinylidene chloride, vinyl acetate, vinyl propionate, acrylamide, N-methylolacrylamide, ethylene, and butadiene.

In the cast mode using a heating mirror drum, the above (co) polymer preferably has a glass transition point of 40 ° C. or higher, more preferably 50 to 100 ° C. When the glass transition point is low, film formation proceeds excessively during drying, and the porosity of the surface is reduced. As a result, the ink absorption rate may be reduced. The polymer may be a copolymer using two or more kinds of ethylenic monomers as needed, or may be a polymer or a substituted derivative of the copolymer. By the way,
Examples of the substituted derivative include, for example, those having a carboxyl group or those having been rendered alkali-reactive. The complexation with colloidal silica is carried out by polymerizing the above-mentioned ethylenic monomer with a silane coupling agent or the like in the presence of colloidal silica to form a complex by Si—O—R (R: polymer component) bond, or In which a polymer resin modified with a silanol group or the like is reacted with colloidal silica to form a composite by Si—OR (R: polymer component) bond.

The composition for an undercoat layer composed of the above-mentioned materials is generally adjusted to a solid content concentration of about 5 to 50% by weight, and is dried on a paper substrate in a dry weight of ^{2 to} 100 g / m ² , preferably 5 to 100 g / m ² . About 50 g / m ² , more preferably 10 to 20
g / m ² . If the coating amount is small, the effect of improving the ink absorbency may be small, or the effect of improving the gloss when the gloss layer is provided may not be sufficient.If the amount is large, the print density may decrease or the coating In some cases, the strength of the worked layer is reduced, and powder is easily dropped or scratched. The composition for the undercoat layer is applied by various known and publicly-applied coating apparatuses such as a blade coater, an air knife coater, a roll coater, a brush coater, a chaplex coater, a bar coater, a lip coater, a die coater, a gravure coater, and a curtain coater. , Dried. further,
If necessary, a smoothing treatment such as super calendering or brushing can be performed after drying the undercoat layer. When applying the above-mentioned coating solution for the gloss layer on the undercoat layer, various known coating devices such as a blade coater, an air knife coater, a roll coater, a brush coater, a chaplex coater, a bar coater, and a gravure coater are used. it can. The coating amount of the gloss layer is 1 to 30 as a dry solid content.
g / m ^2, preferably 1.5 to 20 / m ^2, more preferably 3 to 15 g / m ^2. At less than 1 g / m ² , the print density and gloss may not be sufficiently obtained.
If the amount is more than g / m ² , the effect is saturated, drying is burdensome, and operability may be reduced. The recording medium thus obtained solves the above-mentioned problems, and an ink jet recording medium having excellent surface strength can be obtained. However, the recording medium can be subjected to a treatment for improving the gloss.

Further, the glossy layer can be made glossy by applying a coating solution for the glossy layer, drying the coating solution, and then performing a super calender treatment or the like. Also, it is preferable to form the gloss layer by a cast method, since the gloss is particularly excellent. The cast method means that the coating layer is made of a cast drum with smoothness (drum of mirror-finished metal, plastic, glass, etc.), a mirror-finished metal plate, a plastic sheet or film,
This is a method of drying on a glass plate or the like and transferring a smooth surface onto the coating layer to obtain a smooth and glossy coating layer surface. As a method of providing a glossy layer by a cast method, the above-mentioned glossy layer coating solution is coated on an undercoat layer, and pressed against a mirror-surface drum or the like heated while the coating layer is in a wet state, Drying and finishing method (wet casting method),
Alternatively, there may be mentioned a method in which the material is dried and then re-wetted and then pressed against a heated mirror drum or the like, followed by drying and finishing (rewet casting method), or a gelling casting method. Generally, the wet cast method tends to be excellent in gloss and ink absorbency, and the rewet cast method tends to be excellent in productivity. Further, a method of directly applying a coating liquid for a glossy layer onto a heated mirror drum or the like, followed by pressing and drying the undercoat layer surface of a base material provided with an undercoat layer (precast method) can also be employed.

Further, the above-mentioned coating liquid for a gloss layer is coated on the undercoat layer, and the coated layer is dried to a certain extent, and while being in a semi-dry state, pressed against a heated mirror drum or the like. Drying is particularly preferable because a uniform coating layer is easily formed, a print density is high, and a gloss layer having excellent gloss is easily obtained. Here, "semi-dried" means a state in which the fluidity of the coating layer is almost lost, but a large amount of water is contained. (Including moisture of 20 to 400 parts by weight with respect to 100 parts by weight of absolute dry weight).
It is adjusted in the range of 0 to 200%. If the water content is low, the transfer of the mirror surface when pressed against the mirror drum is insufficient, and it is difficult to achieve a sufficient gloss.If the water content is high, the coating layer is crushed when pressed against the mirror drum, and a uniform and sufficient coating amount is obtained. A coating layer cannot be obtained, and print density and gloss tend to be insufficient.

Applying a coating solution for a glossy layer on the undercoat layer,
In the case where the undercoat layer is pressed against a heated mirror drum or the like while the undercoat layer is in a wet state and dried to finish the coating, the coating liquid for the gloss layer is immobilized in order to obtain a uniform and sufficient coating amount of the coating layer. There are ways to promote it. For example, this method
(1) A gelling agent which promotes immobilization of the glossy layer coating liquid is blended in the undercoat layer. (2) A gelling agent which promotes the immobilization of the glossy layer coating liquid on the undercoat layer is prepared. (3) After applying the gloss layer coating liquid, apply and impregnate the surface with a gelling agent that promotes immobilization of the gloss layer coating liquid. (4) A gelling agent that promotes immobilization in the process of drying the coating liquid is added to the gloss layer coating liquid. As such a gelling agent,
Examples thereof include boric acid, formic acid, and the like, and salts thereof, aldehyde compounds, epoxy compounds, and the like, which are crosslinking agents for the adhesive in the gloss layer coating liquid. After coating and drying or semi-drying the coating composition for a gloss layer, the same coating composition may be further coated on the coating layer and dried on a cast drum or the like.

Further, a film casting method in which a smooth surface is transferred using a smooth film can be applied. A recording medium can be obtained by applying a film to a wet gloss layer and drying the film, or providing a gloss layer on the film, transferring the film to a support, and peeling the film.

[0029]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is by no means restricted thereto.
Parts and% in Examples are parts by weight and% by weight, respectively, unless otherwise specified. Preparation of paper substrate Wood pulp (LBKP; freeness 500 ml CSF) 10
0 parts, calcined kaolin (trade name: Ansilex) 10
Parts, a commercial sizing agent 0.05 parts, a sulfuric acid band 1.5 parts, a wet paper strength agent 0.5 parts, and a starch making material 0.75 parts. and making paper substrates m ^2. The Stockigt sizing degree of this paper substrate was 10 seconds. This paper substrate was used in all examples and comparative examples of the present invention. Preparation of Silica Fine Particles [Silica Fine Particles A] Synthetic amorphous silica (trade name: Fine Seal X-45, manufactured by Tokuyama Corporation; secondary particle diameter: 4.
Using an aqueous dispersion having a particle size of 5 μm and a primary particle size of 15 nm, the pulverization operation was repeated using a pressure-type homogenizer (trade name: ultrahigh-pressure type homogenizer GM-1 manufactured by SMT) (pressurization: 500 kg / cm ^2). ). After the treatment, the dispersion had an average secondary particle size of 50 nm and a solid content of 12%. [Silica fine particles B] Synthetic amorphous silica (manufactured by Nippon Silica Industry Co., Ltd., trade name: Nipsil LP, secondary particle diameter 9μ)
Using an aqueous dispersion having a primary particle diameter of 16 nm and a pressure homogenizer (trade name: Ultra High Pressure Homogenizer GM-1 manufactured by SMT), the pulverization operation was repeated (pressurization: 500 kg / cm ^2). ). Average of dispersion after treatment 2
The secondary particle diameter was 600 nm, and the solid concentration was 12%.

"Mixing of Silica Fine Particles and Cationic Compound" The mixing method in the following Examples and Comparative Examples will be described. And the silica fine particles A or silica fine particles B described above,
When the cationic compound is mixed, the silica is aggregated by mixing both, and the silica is aggregated, and this is mixed with a pressure type homogenizer (trade name, manufactured by SMT Co., Ltd .; trade name: ultra-high pressure type homogenizer G).
M-1) (pressurized to 500 kg / cm ² )
Pulverization treatment was performed until the average secondary particle diameter of silica in the dispersion became the average secondary particle diameter of the original silica fine particles (the primary particle diameter was unchanged). For example, a mixture of silica and a cationic resin having a primary particle size of 15 nm and a secondary particle size of 50 nm is obtained from the silica fine particles A.

Example 1 On a paper substrate, the following coating solution for an undercoat layer was applied in a dry weight of 13%.
g / m ² with an air knife coater.
Dried. Next, the following coating liquid for a cast coating layer is applied on the above-mentioned undercoat layer with an air knife coater, dried for 20 seconds with cold air to be in a semi-dried state (moisture content with respect to the absolute dry amount of the coating layer). (150%), and pressed against a mirror-surface drum having a surface temperature of 90 ° C., dried, and released. The coating amount of the cast coating layer at this time was 6 g / m ² in terms of solid content weight. Coating solution for undercoat layer (solids concentration 20%, parts are solids weight
Indicates a part. ) 80 parts of synthetic amorphous silica (Nip Seal E-150K; manufactured by Nippon Silica Co., Ltd., BET specific surface area 90 m ² / g, average particle diameter 4.5 μm), zeolite (Toyo Builder; manufactured by Tosoh, average particle diameter 1.5 μm) 20 parts, silyl-modified polyvinyl alcohol (R1130; manufactured by Kuraray) 20 parts, copolymer of styrene-acrylic resin and colloidal silica (Movinyl 8055; Hoechst synthesis, Tg = 80 ° C.)
40 parts, 2 parts of fluorescent dye (WhitexBPSH; manufactured by Sumitomo Chemical).

Coating solution for cast coating layer (solids concentration 12
% And parts indicate parts by weight of the solid content. ) 100 parts of silica fine particles A as a pigment, 10 parts of diallyldimethylammonium chloride-acrylamide copolymer (PAS-J-81; manufactured by Nitto Boseki), polyallylamine as a cationic resin (PAA-HCl-3L; manufactured by Nitto Boseki) 5 parts, diallyldimethylammonium chloride (CP-91; manufactured by SENKA) as a cationic resin, 5
Parts, 30 parts of a cationic polyurethane resin (F-8564D; manufactured by Daiichi Kogyo Kagaku, Tg = 73 ° C.), 10 parts of a release agent (Pertor N-856; manufactured by Hyundai Chemical Industry, polyethylene wax), carboxymethyl group (substituted) 5) Cellulose derivatives having a nitric acid ester group (degree of substitution 1.1).

Example 2 In the coating liquid for a cast coating layer used in Example 1, the gloss type was changed in the same manner as in Example 1 except that the number of parts of the cellulose derivative was changed from 5 parts to 0.5 part. Was obtained. Example 3 A glossy inkjet recording paper was prepared in the same manner as in Example 1 except that the number of parts of the cellulose derivative was changed from 5 parts to 20 parts in the coating liquid for a cast coating layer used in Example 1. Obtained. Example 4 In the coating liquid for a cast coating layer used in Example 1, the cellulose derivative was converted to a cellulose derivative having a carboxymethyl group (degree of substitution: 0.5) and a nitrate ester group (degree of substitution: 1.9). A gloss type ink jet recording sheet was obtained in the same manner as in Example 1 except for the change.

Example 5 In the coating liquid for a cast coating layer used in Example 1, the cellulose derivative had a carboxymethyl group (substitution degree: 0.7) and a nitrate ester group (substitution degree: 1.9). A gloss type inkjet recording paper was obtained in the same manner as in Example 1 except that the cellulose derivative was used. Example 6 An undercoat layer coating liquid similar to that of Example 1 was applied on a paper base material with an air knife coater so as to have a dry weight of 13 g / m ² , and dried. Next, the same coating liquid for a cast coating layer as in Example 1 was applied onto the undercoat layer with an air knife coater, immediately pressed against a mirror drum having a surface temperature of 90 ° C., dried, and then separated. Then, a gloss type ink jet recording paper was obtained. The coating amount of the cast coating layer at this time was 3 g / m ² in terms of solid content weight.

Example 7 In the same manner as in Example 1, except that the number of parts of the cellulose derivative was changed from 5 parts to 50 parts in the coating liquid for a cast coating layer used in Example 1, a glossy inkjet was used. Recording paper was obtained. Comparative Example 1 A gloss type inkjet recording paper was prepared in the same manner as in Example 1 except that the number of parts of the cellulose derivative was changed from 5 parts to no addition in the coating liquid for the cast coating layer used in Example 1. Obtained. Comparative Example 2 A gloss type inkjet recording paper was obtained in the same manner as in Example 1 except that the number of parts of the cellulose derivative was changed from 5 parts to no addition in the coating liquid for the cast coating layer used in Example 6. Was. Comparative Example 3 In the coating liquid for a cast coating layer used in Example 1, except that the silica fine particles were changed from A to silica fine particles B,
In the same manner as in Example 1, a gloss type ink jet recording paper was obtained.

Comparative Example 4 Example 1 was repeated except that the cellulose derivative was changed to carboxymethylcellulose (Cellogen 7A; manufactured by Daiichi Kogyo Seiyaku) in the coating solution for the cast coating layer used in Example 1.
In the same manner as described above, a gloss type ink jet recording paper was obtained.

Table 1 summarizes the suitability for ink-jet recording and the gloss of white paper of the ink-jet recording paper thus obtained. In addition, about the said evaluation, evaluation was performed by the following methods. [Surface strength] Friction tester specified in JIS-L0849
Using a II type (Gakushin type) (friction load: 200 g), affix black paper to the friction element, rub the paper back and forth five times on the glossy surface of the ink jet recording paper, and visually check the paper dust adhesion part on the black paper. The coating strength was determined according to the following criteria. ：: Paper powder slightly adheres to black paper, and surface strength is high. 〇-: A level at which paper dust adheres to black paper but does not cause a problem in practical use. X: Paper powder adheres considerably to black paper, and surface strength is extremely low.

[Glossiness] A 75 ° glossiness of a blank portion was measured according to JIS-P8142. [Visual glossiness] The glossiness was visually evaluated. ：: Excellent. X: remarkably inferior. [Inkjet recording suitability] Printing was performed using an inkjet printer BJC420J (using a photo ink cartridge BC-22e manufactured by Canon Inc.). (Uniformity of solid printing portion) The printing unevenness (shading unevenness) of the solid printing portion in which two colors of cyan ink and magenta ink were mixed was visually evaluated. ：: good level without printing unevenness X: A level at which printing unevenness is remarkable and becomes a serious problem in practical use.

(Print bleeding) Solid printing portions of black, cyan, magenta, and yellow inks were printed so that their borders were in contact with each other, and bleeding at the borders was visually evaluated. 〇: Good level without bleeding. X: A level at which bleeding is remarkable and becomes a serious problem in practical use. (Print density after inkjet recording) The print density of the black solid print portion was measured by Macbeth RD-914. [Comprehensive evaluation] The print quality, gloss and surface strength were comprehensively evaluated. 5: Extremely excellent. 4: Excellent. 3: Normal. 2: Slightly inferior. 1: Poor.

[0040]

[Table 1]

[0041]

According to the present invention, the gloss of the blank portion and the printing portion can be improved.
The ink jet recording paper was excellent in the surface strength of the white paper portion, did not reduce the gloss in the subsequent steps, and was excellent in ink jet recording suitability such as print density, ink absorbency, and recording image quality.

Claims (5)

[Claims] 1. In an ink jet recording paper provided with a gloss layer containing a pigment and an adhesive on a substrate, the gloss layer is
An ink jet recording sheet comprising a cellulose derivative having a carboxyalkyl group and a nitrate group as a substituent, and wherein the pigment in the glossy layer contains a pigment having an average particle size of 500 nm or less. 2. The method according to claim 1, wherein the undercoat layer containing a pigment and an adhesive is at least one layer between the substrate and the glossy layer, and the pigment having an average particle size of 500 nm or less in the glossy layer has an average primary particle size of 3 nm.
Not less than 40 nm, the average particle diameter of the secondary particles is 10 nm or more and 400 n
2. An ink jet recording sheet according to claim 1, wherein the sheet is silica fine particles having a particle size of m or less. 3. The ink jet recording paper according to claim 1, wherein the glossy layer is formed by a cast method. 4. The ink jet recording paper according to claim 1, wherein the carboxyalkyl group is a carboxymethyl group. 5. An ink jet recording paper having a substrate provided with a coating layer containing a cellulose derivative having a carboxyalkyl group and a nitrate ester group.