WO2002072360A1

WO2002072360A1 - Inkjet recording sheets

Info

Publication number: WO2002072360A1
Application number: PCT/JP2002/001368
Authority: WO
Inventors: Mitsuhiro Ikeda; Hideki Sekiguchi
Original assignee: Mitsubishi Paper Mills Limited
Priority date: 2001-03-14
Filing date: 2002-02-18
Publication date: 2002-09-19
Also published as: JP2002264483A

Abstract

The present invention provides inkjet recording sheets which have high gloss, high printing density, excellent ink absorbability, and good color reproducibility and image reproducibility, more particularly, an inkjet recording sheet comprising a support and a gloss-imparting layer formed by casting on the support wherein the gloss-imparting layer contains a water-holding agent and inorganic fines having primary particle diameters of 100 nm or below. The coating fluid for forming the gloss-imparting layer preferably exhibits a ratio of pressure dehydration of less than 75 %. The content of the water-holding agent is preferably 0.5 to 5 % by mass. The water-holding agent is preferably a polymer having carboxyl groups. The gloss- imparting layer preferably contains organic fine particles having primary particle diameters of 100 nm or below. The sheet preferably has an ink-receiving layer containing a porous inorganic pigment between the support and the gloss-imparting layer.

Description

Description Inkjet recording sheet

Technical field

The present invention relates to an ink jet recording sheet, and more particularly, to an ink jet recording sheet having a surface gloss.

Background art

In the ink jet recording method, ink droplets are made to fly by various operating principles and adhere to a recording sheet such as paper to record images and characters. The recording method has features such as high speed, low noise, easy multi-coloring, great flexibility of recording pattern, no need for development and fixing, etc. As a device, it is rapidly spreading in various applications. Furthermore, multi-color printing using multi-color ink-jet printing can provide a record comparable to that of color photographic printing, and is cheaper than photographic technology for applications that require fewer copies. It is being widely applied to the full-color image recording field.

In addition, printers that use the ink-jet method are working to increase the resolution and expand the color reproduction range in response to demands from the market for further improvements in image quality. Accordingly, it is indispensable for the ink jet recording sheet as a recording medium to secure a high ink receiving capacity for exhibiting excellent image quality and to apply a coating layer having a good coloring property. It has been demanded that the surface appearance, such as surface gloss, rigidity and hue, be similar to silver halide photographic paper and printing paper.

However, there are recording papers, films, etc. coated with a resin that absorbs ink by dissolution and swelling for the purpose of imparting gloss.However, those that attempt to absorb ink by dissolution and swelling of such a resin are: Although gloss can be obtained, ink absorption and drying speed are slow, and the transfer of ink causes stains and bleeding.

In addition, as a processing method for imparting gloss, using a force rendering device such as a super calender or a Daros calender, a paper is applied by passing paper between rolls under pressure or temperature. It is generally known to smooth the surface of a layer. However, if force rendering treatment is performed under high linear pressure in order to impart gloss to the ink jet recording sheet, the gloss improves but the coating layer voids decrease, the ink absorption slows down, and the absorption capacity becomes insufficient. It is difficult to obtain high gloss by calendering because of the problem of ink overflow.

As a technique for imparting a high gloss to the coating layer without lowering the ink absorbency, for example, JP-A-63-265680, JP-A-2-2747457 Japanese Patent Laid-Open Publication No. 5-59694 discloses a method of manufacturing an ink jet recording sheet by a cast coating method. According to this method, since the mirror surface shape of the cast drum is transferred to the ink jet recording sheet, the surface smoothness is very high, and a strong gloss can be obtained. In addition, since the linear pressure at the time of pressing against the cast drum is lower than that in the case of using a force renderer, good ink absorption can be obtained.

As an ink jet recording sheet that satisfies such requirements, an ink jet recording sheet provided with a layer composed of colloid particles, latex, water-soluble i-polymer, etc. by a cast coating method has been proposed. However, it is difficult to obtain gloss with the combination of materials that have been used in the past! / Was the thing.

An object of the present invention is to provide an ink jet recording sheet having high ink absorbency, print density, surface gloss, and excellent color reproducibility and image reproducibility in printing in ink jet recording. An object of the present invention is to provide an ink jet recording sheet for full-color recording, which is required to have a glossiness at a level of a commercially available cast-coated paper for printing applied to paper, offset printing, tags and labels.

Disclosure of the invention

The present inventors have conducted intensive studies on the ink jet recording sheet. As a result, in the ink jet recording sheet having a glossy layer provided on at least one surface of the support, the glossy layer is in a wet state. It is manufactured by a cast coating method in which a mirror gloss finish is performed by pressing against a mirror roll heated in between, and the gloss development layer comprises a water retention agent and inorganic fine particles having a primary particle diameter of 100 nm or less. The object of the present invention could be solved by comprising the coating composition containing In the coating liquid containing the coating composition, it is preferable that the ratio of the amount of dehydration under pressure represented by the following formula 1 is less than 75%, since high surface gloss can be obtained.

A = (B / C) X 100 0 (1)

In the formula 1, A is the pressure dehydration ratio (%), B is the pressure dehydration amount of the coating liquid (g / m ² ), and C is the coating liquid containing no water retention agent in the coating liquid. Represents the amount of dehydration under pressure (g / m ² ).

When the content of the water retention agent in the coating composition constituting the glossy layer is 0.5% by mass or more and 5% by mass or less, the ink absorption is impaired. It is preferable because a high surface gloss can be obtained without using.

It is preferable that the water retention agent is a polymer having a carboxyl group as a functional group. The surface gloss can be enhanced by including organic fine particles having primary particles of 100 nm or less in the coating composition.

Furthermore, by providing an ink receiving layer containing a porous inorganic pigment between the support and the glossy layer, ink absorbency can be increased and cockling after printing can be suppressed. It is preferred.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the inkjet recording sheet of the present invention will be described in detail. The ink jet recording sheet of the present invention is provided with a gloss-developing layer on at least one surface of the support, and presses against a mirror port heated while the gloss-developing layer is in a wet state to bring the specular gloss into contact. An ink jet recording sheet comprising a coating composition comprising a water retention agent and inorganic fine particles having a primary particle diameter of 100 nm or less, wherein the gloss-developing layer is manufactured by a cast coating method to be finished. It is.

With the cast coating method, after applying a coating liquid comprising a coating composition constituting a glossy layer, the coated surface is brought into contact with a heated mirror surface while the coated surface is in a wet state. This is a method of pressing, drying, peeling off, and forming a replica of the mirror surface roll on the coating surface.

Common cast coating methods include the direct method, the coagulation method, and the rewet method. The direct method is a method in which the glossy layer is applied and then pressed against a heated mirror roll in an undried state (wet state) and dried. This is a method in which the coating composition for the expression layer is solidified with an acid solution, an alkaline solution, or the like, and then pressed against a heated mirror-finished roll. Incidentally, the coagulation method also includes a thermal coagulation method of irradiating the composition with infrared rays to solidify the surface. The rewet method is a method in which the glossy layer is applied, dried, then rewet with a liquid mainly composed of water, pressed against a heated mirror surface, and dried. In the present invention, any cast coating method may be used as necessary.

The water retention agent referred to in the present invention increases the water retention of a coating liquid comprising a coating composition constituting a glossy layer.

More specifically, the water retention of the present invention is generally measured by a pressure dehydration method. As a tester for the pressure dewatering method, for example, Gravimetric Water manufactured by Kaltec Scientific

Retention Meter is commercially available. An example of measuring water retention by the pressure dehydration method is shown below.

Measurement example: Kaltec Scientific Gravimetric Water

Using a Retention Meter, place a filter with a pore size of 0.05 / xm (Millipore VMW-VM) on the metal mesh below the coating liquid inlet of this tester, and place it under the metal mesh. Put the filter paper (Advantech 26 filter paper). Put 10 ml of the coating liquid into the coating liquid inlet of the tester, and apply a pressure of 50 kPa, a pressurizing time of 60 seconds, a temperature of 23 ° C, and a pore diameter of 0.05 Aim. Measure the amount of water that passes through the filter and is absorbed by the filter paper below the metal mesh (pressure dehydration). When water retention is high, the amount of dehydration under pressure is small. On the other hand, when water retention is low, the amount of dehydration under pressure is large. The amount of dehydration under pressure converted to the amount of dehydration under pressure per unit area of the filter (g / m ² ) is used as an index of water retention.

The water retention agent referred to in the present invention is one that increases the water retention measured by the pressure dehydration method or the like exemplified above (the pressure dehydration amount is reduced by the method exemplified in the measurement example). When the water retention of the coating liquid comprising the coating composition constituting the glossy layer is high, a high surface gloss can be obtained when the coating liquid is pressed against a mirror roll and dried. On the other hand, when the water retention of the coating liquid is low, it is difficult to obtain high gloss. Therefore, the amount of dehydration under pressure of the coating liquid containing a water retention agent is set to be less than 75% by mass as compared with the amount of dehydration under pressure of the coating liquid containing no water retention agent. The coating liquid contains a water retention agent preferable. When the content is 75% by mass or more, only the same degree of gloss may be obtained as compared with the case where the water retention agent is not contained.

Even in general cast coated paper used for offset printing and the like, a water retaining agent may be contained in the coating liquid in order to increase the water retention of the coating liquid. Is generally 0.1 to 0.3% by mass.

On the other hand, in the case of an ink jet recording sheet, a support or the like (for example, paper as a support, an ink receiving layer provided between the support and a glossy layer as needed) needs to have ink absorbency. For this reason, water during the coating is easily absorbed by the support and the like at the time of coating, and the content of a general water retention agent is insufficient. Therefore, in order to obtain sufficient water retention, the content of the water retention agent in the coating composition is preferably 0.5% by mass or more and 5% by mass or less. If the content of the water retention agent in the coating composition is less than 5% by mass, the water retention becomes insufficient and high gloss may not be obtained. If the content exceeds 5% by mass, the water retention agent becomes luminous. In some cases, the absorption of ink may be impaired because the voids in the developing layer are filled. Examples of the water retention agent of the present invention include polyatalylate, polymethacrylate, urethane acrylate copolymer, urethane methacrylate copolymer, crosslinked polyatalylate, crosslinked polymethacrylate, methacrylic acid / acrylic acid. Acid copolymers, methacrylic acid / noacrylic acid ester copolymers, methacrylic acid esters / acrylic acid copolymers, alginates, polyvinyl lactam / polyamide graphitic polymers, carboxymethyl cellulose, etc. It is not limited to these.

In addition, when a polymer having a carboxyl group as a functional group is used as a water retention agent, even if its content is high, not only does it hardly inhibit ink absorption, but it also increases water retention due to ρ 液 of the coating liquid. Can be easily adjusted, and the surface gloss can be adjusted by the coating liquid ρΗ.

The inorganic fine particles contained in the glossy layer used in the present invention must have a primary particle diameter of 100 nm or less. The preferred primary particle size of the inorganic fine particles is 5 nm or more and 50 nm or less. If the primary particle diameter of the inorganic fine particles exceeds 100 nm, the transparency of the gloss-developing layer is reduced, so that it is difficult to obtain a sufficient surface gloss. Also, when the primary particle diameter of the inorganic fine particles is less than 5 nm, the pores become too small. Absorption speed may be slow.

As such inorganic fine particles, silica, alumina or alumina hydrate fine particles such as colloidal silica force, alumina sol, alumina / silica composite sol, fumed silica, and fumed alumina have high transparency. It is preferable because high gloss is easily obtained. The content of the inorganic fine particles in the coating composition is preferably 30% by mass or more and 80% by mass or less! / ,. The content of inorganic fine particles is 30 mass ⁰ /. When the amount is less than the above, the voids of the gloss-developing layer may be reduced, and the ink absorption may be impaired. When the amount exceeds 80% by mass, the coating strength of the gloss-imparting layer may be weakened.

In addition, by adding organic fine particles which are deformed by heat to the coating composition, the surface gloss can be increased.

The organic fine particles referred to in the present invention are those in which the individual fine particles do not fuse to form a film or the like when dried at room temperature. Further, such organic fine particles are sometimes referred to as plastic pigments.

The glass transition temperature of the organic fine particles of the present invention is preferably 30 ° C. or more and 150 ° C. or less, particularly preferably 50 ° C. or more because the ink absorption is not hindered even after drying and gloss is easily obtained. 30 ° C. or lower is preferred. If the temperature is lower than 50 ° C, it may be fused at the time of drying and may hinder the absorption of ink. On the other hand, when the temperature exceeds 150 ° C., even when pressed against a heated mirror-finished roll, thermal deformation does not occur and gloss may not be easily obtained.

Examples of such organic fine particles include acrylic resins, polyolefin resins, urea resins, melamine resins, and the like. The present invention is not limited to these, but an acrylic resin is preferred because the glass transition temperature can be easily adjusted and gloss can be easily obtained. Particularly, an acrylic resin containing methacrylic acid ester as a structural unit is preferably a gloss resin. It is preferable because the ink absorption is high. The particle shape of the organic fine particles can be exemplified by a sphere, a hollow sphere and the like, and is not particularly limited. The organic fine particles contained in the glossy layer also preferably have a primary particle size of 100 nm or less. When the primary particle size of the organic fine particles exceeds 100 nm, the transparency of the glossy layer is reduced, so that it is difficult to obtain a sufficient surface gloss.

The content of the organic fine particles in the coating composition is preferably 50% by mass or less. If it exceeds 50% by mass, the voids in the glossy layer are reduced, and the ink absorption is reduced. P and may be harmful.

The binder that can be contained in the glossy layer of the present invention is not particularly limited as long as it can maintain an appropriate coating layer strength and does not inhibit the absorption of ink. Examples of the binder include oxidized starch and ether. Aqueous adhesives such as starch derivatives such as modified starch and phosphorylated ester, casein, gelatin, soy protein, polyvinyl alcohol or derivatives thereof, polyvinylpyrrolidone, thermosetting synthetic resins such as maleic anhydride resin, melamine resin and urea resin And synthetic resin adhesives such as polyvinyl butyral and alkyd resin. The content of the binder in the coating composition constituting the glossy layer is 5 to 50% by mass, preferably 10 to 30% by mass. However, if it exceeds 50% by mass, the ink absorbency may decrease.

Furthermore, in the glossy layer, additives such as a dye fixing agent, a pigment dispersant, an antifoaming agent, an antifoaming agent, a release agent, a foaming agent, a penetrant, a coloring dye, a coloring pigment, a fluorescent whitening agent, and an ultraviolet ray An absorbent, an antioxidant, a preservative, an anti-binder, a water-proofing agent, a wet paper strength enhancer, a dry paper strength enhancer, and the like can be appropriately compounded.

The method for applying the glossy layer is as follows: various blade coaters, roll coaters, air ■ ~ knife coater, no ■ ~ co ¹ ~ ~ ta '~ ~, rod blur ¹ ~ do coater ¹ ~- Various devices such as a short dowel coater and a size press can be used. The amount of the glossy layer to be applied varies depending on the method of the casting treatment and the required gloss, but may be 2 g Zn ^ or more. After the casting process, it is also possible to blow curl air and humidified steam on the back side of the glossy layer sandwiching the support to correct the curl. In addition, machine power render, TG calendar, super power render, soft curry A force rendering device such as a renderer may be used.

On the other hand, a porous inorganic pigment is contained between the glossy layer and the support for the purpose of increasing the ink absorbency and suppressing cockling due to the penetration of the ink into the support base paper. It is preferable to provide an ink receiving layer.

The ink receiving layer of the present invention comprises a coating composition containing a porous inorganic pigment and a binder as main components. As the pigment, one or more publicly known white pigments can be used. For example, light calcium carbonate, heavy calcium carbonate, Gnesium, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, amorphous silica, colloidal silica, anoremina, White inorganic pigments such as colloidal alumina, alumina hydrate (pseudo-boehmite, aluminum hydroxide, etc.), lithobon, zeolite, hydrohalosite, magnesium hydroxide and the like can be mentioned.

As the porous inorganic pigment, amorphous silica, alumina, and alumina hydrate are preferred because of their large ink absorption capacity.

The binder that can be contained in the ink receiving layer of the present invention is not particularly limited as long as it can maintain an appropriate coating layer strength and does not inhibit the absorption of the ink. Starch derivatives such as etherified starch and phosphorylated ester starch, cellulose derivatives such as carboxymethyl senorelose and hydroxyethyl cellulose, casein, gelatin, soy protein, polyvinyl alcohol or derivatives thereof, polyvinylpyrrolidone, and maleic anhydride Conjugated copolymer latex such as resin, styrene / butadiene copolymer, methyl methacrylate / butadiene copolymer, acrylic polymer latex such as acrylic acid and methacrylic acid ester polymer or copolymer , Such as ethylene-vinyl acetate copolymer Polymer latex, or a functional group-modified polymer with a monomer containing a functional group such as lipoxyl group of these various polymers Latettus, water-based adhesive such as melamine resin, thermosetting synthetic resin such as urea resin, polymethyl Synthetic resin-based adhesives such as polymer or copolymer resin of acrylate, methacrylate, etc., methacrylate ester, polyurethane resin, unsaturated polyester resin, vinyl chloride / butyl acetate copolymer, polyvinylinolebutyral, and alkyd resin Agents and the like. The amount of the binder is from 5 to 70 parts by mass, preferably from 5 to 50 parts by mass, preferably from 50 to 50 parts by mass, based on 100 parts by mass of the solid content of the porous inorganic pigment. The coating strength of the layer is insufficient, and if it exceeds 70 parts by mass, the ink absorbency decreases.

Further, the ink receiving layer contains, as additives, dye fixing agents, pigment dispersants, thickeners, flow improvers, defoamers, foam suppressors, release agents, foaming agents, penetrants, coloring dyes, Color pigments, optical brighteners, UV absorbers, antioxidants, preservatives, anti-binders, water-proofing agents, wet paper A strength enhancer, a dry paper strength enhancer and the like can be appropriately compounded.

In particular, secondary amine, tertiary amine, and quaternary ammonium salts that form insoluble salts with the sulfonate group, carboxyl group, amino group, etc. in water-soluble direct dyes and water-soluble acid dyes, which are the components of aqueous inks When a cationic dye fixing agent consisting of is mixed with the dye, the dye is captured in the ink receiving layer, and the color is improved. ゃ The formation of insoluble salts causes the ink to flow out due to dripping of water or moisture absorption. Is preferred because

The coating amount of the ink receiving layer is preferably 3 g / m ² or more in order to effectively suppress cockling.

The method of applying the ink receiving layer is as follows: various machines such as blade coater, roll coater, air knife coater, bar coater, rod blade coater, curtain coater 1, short dowel coater, size press, etc. Or it can be used off-machine. Further, after coating, it is also possible to perform a flattening finish using a calendar device such as a machine calendar, a TG calendar, a super calendar, a soft calendar, or the like.

Examples of the support used in the present invention include chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP and CGP, and waste paper pulp such as DIP. Of wood pulp and conventionally known pigments as main components, using one or more binders and various additives such as sizing agents, fixing agents, retention agents, cationizing agents, paper strength agents, etc. Base paper manufactured by various devices such as paper machine, round paper machine, twin wire paper machine, etc., base paper with size press with starch, polyvinyl alcohol, etc., base paper with anchor coat layer, and coating on them Coated paper such as art paper, coated paper, cast-coated paper, etc. with a layer is also included. Such a base paper and a coated paper may be provided with the coating layer according to the present invention as they are, or a calendar device such as a machine calendar, a TG calendar, or a soft force renderer may be used for the purpose of controlling flattening. May be. The basis weight of the support is usually from 40 to 300 g Zm ² , and is not particularly limited.

In addition, the air permeability or air permeability of the support is necessary for transferring the vapor generated when the gloss-generating layer is cast to the back surface to dry the gloss-generating layer. Because paper is an important factor in determining the releasability of the layer, As long as it has air permeability or air permeability, it may be formed into a sheet after fibrous synthetic resin such as polyethylene, polypropylene, polyester, rayon, and polyurethane.

The ink jet recording sheet of the present invention is not limited to use as an ink jet recording sheet, and may be used as any recording sheet that uses liquid ink during recording. For example, an ink sheet obtained by applying a heat-fusible ink containing a heat-fusible substance or a dye / pigment as the main component on a thin support such as a resin film, high-density paper, or synthetic paper is heated from the back by a force P. Thermal transfer recording image-receiving sheet that melts and transfers ink, ink-jet recording sheet that heat-fuses and melts hot-melt ink to form microdroplets, ink-jet recording sheet for flight recording, and ink-jet using ink in which oil-soluble dye is dissolved in solvent My containing a recording sheet, photopolymerizable monomer and colorless or colored dye. An image receiving sheet or the like corresponding to a photosensitive pressure-sensitive donor sheet using crocapsule may be used. The common feature of these recording sheets is that the ink is in a liquid state during recording. The liquid ink permeates or spreads in the depth direction or the horizontal direction on the ink absorbing layer side of the recording sheet until it is cured, solidified or fixed. The above-mentioned various recording sheets require absorptivity according to each method, and the ink jet recording sheet of the present invention may be used as the above-mentioned various recording sheets.

Furthermore, the ink jet recording sheet of the present invention may be used as a recording sheet for heating and fixing an electrophotographic recording type toner widely used in copiers, printers, and the like. It can also be used for labeling.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples. Further, “parts” and “%” shown in the examples represent parts by mass and mass% of solid components or substantial components unless otherwise specified.

Preparation of support>

The support was made of 100 parts of wood pulp consisting of 80 parts of LBKP (freeness of 400 m1 csf) and 20 parts of NBKP (freeness of 45 Om1csf). 25 parts of pigment with a ratio of palladium / heavy calcium carbonate / talc of 10/10/10, 0.10 parts of commercially available alkyl ketene dimer, commercially available cationic (meth) acrylamide 0.03 parts, commercially available cationized starch 0.80 parts, sulfuric acid band 0.40 parts A slurry having a solid content of 1% containing water in a concentration of 1% was prepared, and the basis weight was 90 g / m ² using a fourdrinier paper machine. The paper was made.

According to the method described below, 21 types of glossy layer coating solutions (coating solutions (A) to (N) and (a) to (g)) were prepared.

Coating solution (A): 100 parts of Snowtex 50 (colloidal silica, particle diameter 20-30 nm, manufactured by Nissan Chemical Industries) as inorganic fine particles, SN 924 (copolymer of methacrylic acid and acrylic ester, 0.13 parts (solid content of water retention agent with respect to total coating composition: 0.1%), styrene'butadiene latex (trade name: JSR Latex 0693, average particle diameter: 135 nm, JSR) Co., Ltd.), 30 parts of commercially available potassium oleate and water were used to adjust the solids concentration to 25% and PH 8.5 to prepare a glossy layer coating solution (A).

Coating solution (B): 0.13 parts of the added water-retaining agent SN 924 of coating solution (A), 0.4 part (0.4% of solid content of water-retaining agent to coating and composition: 0 3%) to prepare a coating solution (B) in the same manner as the coating solution (A).

Coating liquid (C): 0.13 parts of water-retaining agent SN 924 in coating liquid (A) 0.1 parts, 1.0 part (solid content of water-retaining agent to coating composition: 0.75 %), And a coating liquid (C) was prepared in the same manner as the coating liquid (A).

Coating liquid (D): Add 0.13 parts of water-retaining agent SN 924 in coating liquid (A) to 2.0 parts (solid content of water-retaining agent to coating composition: 1.5%) A coating solution (D) was prepared in the same manner as the coating solution (A), except that

Coating liquid (E): 0.13 parts of water-retaining agent SN 924 added to coating liquid (A), 6.5 parts (solid content of water-retaining agent to coating and composition: 4.7 %), And a coating liquid (E) was prepared in the same manner as the coating liquid (A).

Coating liquid (F): 0.13 parts of water-retaining agent SN 924 in coating liquid (A), 8.5 parts (solid content of water-retaining agent to coating composition: 6.0%) A coating solution (F) was prepared in the same manner as the coating solution (A) except that the above conditions were satisfied.

Coating liquid (G): 0.13 parts of SN924 water retention agent for coating liquid (A) VDS (sodium salt of acrylic acid polymer, manufactured by San Nopco) A coating liquid (G) was prepared in the same manner as the coating liquid (A) except that the amount was changed to 2.0 parts. The solid content of the water retention agent in the coating liquid (G) relative to the whole coating composition was 1.5%.

Coating liquid (H): Add Snowtex 50 of the coating liquid (A) to Snowtex XL (colloidal sily force, particle size 40-60 nm, manufactured by Nissan Chemical Industries), and add the water retention agent SN 924 0.1 Coating solution (H) was prepared in the same manner as coating solution (A) except that 3 parts was changed to 2.0 parts. The solid content of the water retention agent in the coating liquid (H) relative to the total coating composition was 1.5%.

Coating solution (I): Add Snowtex 50 of Snow coating 50 (Non-spherical colloidal sily force, particle diameter 40 to 100 nm, manufactured by Nissan Chemical Industries) to Snowtex 50 of coating solution (A). Coating liquid (I) was prepared in the same manner as coating liquid (A) except that 3 parts was changed to 2.0 parts. The solid content of the water retention agent in the coating liquid (I) relative to the total coating composition was 1.5%.

Coating liquid (J): Add 0.13 parts of water retention agent SN 924 to 200 V (vapor phase silica, particle size: 12 nm, manufactured by Nippon Aerosil) with Snowtex 50 in coating liquid (A). A coating solution (J) was prepared in the same manner as the coating solution (A) except that the amount was changed to 2.0 parts. The water retention agent solid content of the coating liquid (J) relative to the total coating composition was 1.5%.

Coating liquid (K): 100 parts of Snowtex 50 (colloidal silica, particle diameter 20-30 nm, manufactured by Nissan Chemical Industries) as inorganic fine particles, SN 924 (copolymer of methacrylic acid and acrylic acid ester) as water retention agent 2.0 parts (solid content of water retention agent to total coating composition: 1.3%), Movinyl 790 (methacrylic acid ester resin) as organic fine particles, glass transition temperature 105 ° C, particle size 60 nm, Clariant Polymer) 25 parts, Styrene butadiene latex (trade name JSR Latex 0693, average particle diameter 135 nm, manufactured by JSR) 30） | 5, using 2 parts of commercially available potassium oleate and water, The glossy layer coating solution (K) was prepared by adjusting the solid content to 25% and the pH to 8.5.

Coating liquid (L): The coating liquid (L) was prepared in the same manner as the coating liquid (K) except that the addition amount of the organic fine particle Movinyl 790 in the coating liquid (K) was changed from 25 parts to 50 parts. Prepared Was. The water retention agent solid content of the coating liquid (L) with respect to the total coating composition was 1.1%. Coating liquid (M): The coating liquid (M) was prepared in the same manner as the coating liquid (K), except that the addition amount of the organic fine particle movinyl 790 in the coating liquid (K) was changed from 25 parts to 90 parts. It was prepared. The water retention agent solid content of the coating liquid (M) with respect to the total coating composition was 0.9%. Coating liquid (N): The organic fine particle Movinyl 790 in the coating liquid (K) was changed to Nippol 2507 (high styrene / butadiene copolymer, glass transition temperature 54 ° C, particle diameter 70 nm, manufactured by Zeon Corporation). A coating solution (N) was prepared in the same manner as the coating solution (K) except for the above. The water retention agent solid content of the coating liquid (N) with respect to the total coating composition was 1.3%.

Coating liquid (a): Coating liquid (a) was prepared in the same manner as coating liquid (A) except that the water retention agent was removed from coating liquid (A).

Coating liquid (b): Coating liquid (b) was prepared in the same manner as coating liquid (H) except that the water retention agent was removed from the coating liquid (H).

Coating liquid (c): Coating liquid (J) power ^ Coating liquid (c) was prepared in the same manner as coating liquid (J) except that water retention agent was removed.

Coating liquid (d): Same as coating liquid (B) except that Snowtex 50 in coating liquid (B) was changed to MP-3040 (colloidal sily force, particle size 300 nm, manufactured by Nissan Chemical Industries, Ltd.). Thus, a coating solution (d) was prepared.

Coating liquid (e): Same as coating liquid (D) except that Snowtex 50 in coating liquid (D) was changed to MP-3040 (colloidal silica, particle diameter 300 nm, manufactured by Nissan Danigaku Kogyo) Thus, a coating solution (e) was prepared.

Coating liquid (f): Coating liquid (f) was prepared in the same manner as coating liquid (L) except that the water retention agent was removed from coating liquid (L).

Coating liquid (g): Same as coating liquid (L) except that Snowtex 50 in coating liquid (L) was changed to MP-3◦40 (colloidal sily force, particle diameter 300 nm, manufactured by Nissan Chemical Industries). Similarly, a coating solution (g) was prepared.

Example 1

The coating solution of the glossy layer of the coating solution (A) was applied on a support by a roll coater to a dry coating amount of 17 g / m ^2, and then cast. Inn A jet recording sheet was prepared. The casting treatment was performed by a direct method of drying by pressing against a mirror surface heated to a surface temperature of 90 ° C. 2 seconds after applying the coating liquid for the glossy layer.

Examples 2 to 10

Ink jet recording sheets of Examples 2 to 10 were produced in the same manner as in Example 1 except that the coating liquid (A) in Example 1 was changed to the coating liquids (B) to (J). Comparative Examples 1 to 5

Ink jet recording sheets of Comparative Examples 1 to 5 were produced in the same manner as in Example 1 except that the coating liquid (A) in Example 1 was changed to the coating liquids (a) to (e). The ink jet recording sheets produced in Examples 1 to 10 and Comparative Examples 1 to 5 were evaluated by the methods described below. The results are shown in Table 1. The evaluation was performed under the environment specified by ISO 187 (23 ° C, 50% RH).

<Gloss>

The specular glossiness of the surface of the cast gloss developing layer was measured. The gloss was measured with a variable angle glossmeter (VGS-1001 DP) manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS Z 8741 with an incident / reflection angle of 75 degrees. When the gloss exceeds 60%, a high gloss is obtained.

Using an ink-jet printer (PM800 C: manufactured by Seiko Epson), a heavy-colored rectangular pattern was printed with cyan ink and magenta ink, and the boundary between this pattern and the blank area was visually evaluated according to the following criteria. . A or B is required for good ink absorption.

A: No bleeding is seen at the boundary.

B: Slight bleeding is seen at the boundary.

C: Bleeding is observed at all of the boundary portions.

Using the above-described ink jet printer, a solid pattern was printed with black ink, and the optical reflection density of the printed portion was measured using Macbeth RD-918. If the printing density is 1.70 or more, a color image can be obtained. For the coating liquids of Examples 1 to 10 and Comparative Examples 1 to 5, the amount of dehydrated carohydrate, which is an index of water retention, was measured in accordance with the above-described measurement example of water retention (pressure dehydration method). The pressure dehydration ratio (%) was calculated by the following equation 1. The smaller the value of the ratio of dehydration under pressure calculated by equation 1, the higher the water retention of the coating liquid. The results are shown in Table 1.

A = (B / C) X 100

A: Ratio of dehydration under pressure (%)

B: Dehydration under pressure of coating liquid containing water retention agent (g / m ² )

C: Amount of dehydration under pressure (g / m ² ) of the coating liquid containing no water retention agent

Table 1 Inorganic fine particles Water retention agent Glossiness Ink printing Pressure dehydration Particle size (nm) Content (%) (%) Absorbency Concentration Quantity ratio (%) Example 1 20 to 30 0.1 56 A 1.92 84 Example 2 20 to 30 0.3 69 A 1.92 71 Example 3 20-30 0.75 73 A 1.93 64 Example 4 20-30 1.5 78 A 1.97 60 Example 5 20-30 4.7 78 B 2.01 52 Example 6 20-30 6.0 79 B 2.04 50 Example Ί 20-30 1.5 68 B 1.92 66 Example 8 40-60 1.5 72 A 1.94 60 Example 9 40-: 100 1.5 75 A 2.00 60 Example 10 12 1.5 75 A 2.01 60 Comparative example 1 20-30 0 49 A 1.92 1 00 Comparative example 2 40-60 0 45 A 1.81 100 Comparative example 3 12 0 46 A 1.88 1 00 Comparative example 4 300 0.3 54 A 1.58 71 Comparative example 5 300 1.5 56 A 1.63 61 Example 1 14 Ink jet recording sheets of Examples 11 to 14 were produced in the same manner as in Example 1 except that the coating liquid (A) in Example 1 was changed to the coating liquids (K) to (N).

Comparative Examples 6, 7

Ink jet recording sheets of Comparative Examples 6 and 7 were produced in the same manner as in Example 1 except that the coating liquid (A) in Example 1 was changed to the coating liquids (f) and (g). With respect to the ink jet recording sheets produced in Examples 11 to 14 and Comparative Examples 6 and 7, the amount of dehydration under pressure was measured in the same manner as in Examples 1 to 10 and Comparative Examples 1 to 5. The results are shown in Table 2.

Table 2 Inorganic fine particles Water retention agent Glossiness Ink printing Pressure dehydration Particle size) Content (%) (%) Absorbency Nos Amount ratio (%) Example 11 20-30 1.3 84 A 1.95 60 Example 12 20-30 1.1 87 A 1.97 60 Example 13 20-30 0.9 88 B 2.02 63 Example 14 20-30 1.3 81 A 1.91 61 Comparative example 6 20-30 0 54 A 1.90 100 Comparative example 7 300 1.1 57 A 1.60 61 Example 15 ~ 26

Coating of ink receiving layer: Fine Seal X 37 B (synthetic amorphous silica, manufactured by Tokuyama) 60 parts, Mizukasil P 78D (synthetic amorphous silica, manufactured by Mizusawa Chemical Industries) 40 parts, PVA 117 (polyvinyl) Alcohol, Kuraray) 30 parts, Sumirezuresin 1001 (cationic dye fixing agent, manufactured by Sumitomo Chemical Co., Ltd.) 20 parts and water are used to adjust the solid content to 17%, and the coating liquid for the ink receiving layer is used. Was prepared. This coating solution is applied on a support with a dry knife coater so that the dry coating amount is 10 g / m ^2.

'Receptive layer coated paper was obtained. Coating liquids (A) to (F) and (H) to (M) were coated on the ink receiving layer of the ink receiving layer coated paper by a roll coater with a dry coating amount of 8 g / After coating so as to obtain m ² , a casting treatment was performed in the same manner as in Example 1 to produce ink jet recording sheets of Examples 15 to 26, respectively.

Comparative Examples 8 to 12

Comparative Examples 8 to 12 were prepared in the same manner as in Example 15 except that the coating liquid (A) in Example 15 was changed to the coating liquids (a), (c), and (e) to (g). A recording sheet was prepared.

Examples 15 to 26 and Comparative Examples 8 to 12 Regarding the ink jet recording sheets produced, ~ 14 and Comparative Examples:! Evaluation was performed in the same manner as in Examples 7 to 7. Table 3 shows the results.

Table 3 Inorganic fine particles Water retention agent Glossiness Ink Print density Particle size (nm) Content (%) (%) Absorbency Example 15 20-30 0.1 57 A 1.85 Example 16 20-30 0.3 68 A 1.88 Example 17 20 ~ 30 0.75 72 A 1.91 Example 18 20 ~ 30 1.5 79 A 1.94 Example 19 20 ~ 30 4.7 78 A 1.98 Example 20 20 ~ 30 6.0 78 A 1.98 Example 21 40 ~ 60 1.5 72 A 1.95 Example 22 40 ~ 100 1.5 74 A 2.00 Example 23 12 1.5 78 A 1.99 Example 24 20 ~ 30 1.3 85 A 1.97 Example 25 20 ~ 30 1.1 85 A 1.97 Example 26 20 ~ 30 0.9 87 A 2.00 Comparative Example 8 20 ~ 30 0 50 A 1.84 Comparative Example 9 12 0 47 A 1.82 Comparative Example 10 300 1.5 54 A 1.56 Comparative Example 11 20-30 0 54 A 1.89 Comparative Example 12 300 1.1 57 A 1.59 Examples 1-6, 8-13, 15-26 Cockling of the produced inkjet recording sheet was evaluated by the method described below. The results are shown in Table 4. The evaluation was performed under the environment specified in IS0187 (23 ° C, 50% RH). <Cock ring>

Using a wide-format ink jet printer (JV2_130, manufactured by Mimaki), 100%, 200%, 250%, and 300% of the ink discharge amount is achieved by mixing four colors of cyan, yellow, and magenta. After adjustment as described above, a 30 cm × 30 cm fill pattern was printed and evaluated according to the following criteria. In practical use, it is necessary that cockling that would cause printing trouble with an ink ejection amount of 200% or more should not be observed.

A: Cockling can be confirmed, but it does not cause printing trouble.

B: The paper is cockling and the print head rubs slightly on the paper.

C: The paper is cockling and the head comes in full contact with the paper, causing printing failure. Table 4 Ink glossy layer

Receptive layer Coating solution 100% 200% 250% 3300% Example 1 None Coating solution (A) AAAB Example 2 None Coating solution (B) AAAB Example 3 None Coating solution (C) AAAB Example 4 None Coating liquid (D) AAAB Example 5 None Coating liquid (E) AABC Example 6 None Coating liquid (F) AABC Example 8 None Coating liquid (H) AAAB Example 9 None Coating liquid (I) AAAB Example 10 None Coating liquid (J) AAAB Example 11 None Coating liquid (K) AAAB Example 12 None Coating Liquid (L) AAAB Example 13 None Coating liquid (M) AABC Example 15 Yes Coating liquid (A) AAAA Example 16 Yes Coating liquid (B) AAAA Example 17 Yes Coating liquid (C) AAAA Example 18 Yes Coating liquid (D) AAAA Example 19 Yes Coating liquid (E) AAAA Example 20 Yes Coating liquid (F) AAAA Example 21 Yes Coating liquid (H) AAAA Example 22 Yes Coating liquid (I) AAAA Example 23 Yes Coating liquid (J) AAAA Example 24 Yes Coating liquid (K) AAAA Example 25 Yes Coating liquid (L) AAAA Example 26 Yes Coating liquid (M) AAAA Example As is clear from the above, an ink jet recording sheet having a high surface gloss can be obtained by providing a glossy layer containing a water retention agent and inorganic fine particles having a particle size of 100 nm or less on a support by casting. In That. Further, by including organic fine particles having a primary particle diameter of 100 nm or less in the gloss-developing layer, the surface gloss can be further enhanced, and further, an ink having a porous inorganic pigment between the support and the gloss-expressing layer. By providing the receiving layer (Examples 15 to 26), it is possible to obtain an ink jet recording sheet with improved ink absorbency and suppressed cockling.

Industrial applicability

ADVANTAGE OF THE INVENTION According to this invention, it has high glossiness, high print density, excellent ink absorption, An ink jet recording sheet having good color reproducibility and image reproducibility can be provided.

Claims

The scope of the claims

1. An ink jet recording sheet having a glossy layer provided on at least one surface of a support, wherein the glossy layer is pressed against a mirror roll heated while the glossy layer is in a wet state to achieve a mirror gloss finish. And an ink jet recording sheet comprising a coating composition in which the gloss-developing layer contains a water retention agent and inorganic fine particles having a primary particle diameter of 100 nm or less.

2. The ink jet recording sheet according to claim 1, wherein in the coating liquid containing the coating composition, the ratio of pressurized dehydration represented by the following formula 1 is less than 75%.

A = (BZ C) X 100 0 (1)

(In the formula 1, A is the pressure dehydration ratio (%), B is the pressure dehydration amount of the coating liquid (g Zm ² ), and C is the coating liquid which does not contain a water retention agent in the coating liquid. Dehydration under pressure (g Zm ² ).)

3. The ink jet recording sheet according to claim 1, wherein the content of the water retention agent in the coating composition is 0.5% by mass or more and 5% by mass or less.

4. The ink jet recording sheet according to claim 2, wherein the content of the water retention agent in the coating composition is 0.5% by mass or more and 5% by mass or less.

5. The ink jet recording sheet according to claim 1, wherein the water retention agent is a polymer having a carboxyl group as a functional group.

6. The ink jet recording sheet according to claim 2, wherein the water retention agent is a polymer having a carboxyl group as a functional group.

7. The ink jet recording sheet according to claim 1, wherein the coating composition contains organic fine particles having a primary particle diameter of 100 nm or less.

8. The ink jet recording sheet according to claim 2, wherein the coating composition contains organic fine particles having a primary particle diameter of 100 nm or less.

9. The ink jet recording sheet according to claim 1, wherein an ink receiving layer containing a porous inorganic pigment is provided between the support and the gloss developing layer.

10. The ink jet recording sheet according to claim 2, wherein an ink receiving layer containing a porous inorganic pigment is provided between the support and the glossy layer.