JP2021011056A - Ink-jet recording paper - Google Patents

Abstract

To provide ink-jet recording paper being suitable for a label, excellent in absorbing properties and color developing properties with respect to a pigmented ink, not causing distortion difference in a glossy feeling between a non-printed part and a printed part, and having glossy feeling in a non-printed part and a printed part.SOLUTION: Ink-jet recording paper which comprises a substrate, an ink-receiving layer on one surface of the substrate, and an adhesive layer on a surface of the substrate, opposite to a surface on which the ink-receiving layer is disposed is such that: the substrate is a coated paper classified under the item [printing, information paper/coating printed paper/coated paper] in Ministry of Economy, Trade, and Industry of Japan/Dynamic Statistics of Production Survey/Paper Monthly Report; the ink-receiving layer positioned at an outermost side in the ink-receiving layers on the basis of the substrate contains at least an alumina hydrate, a binder, a cross-linking agent, an inorganic oxo acid and a wetting agent; and a coating amount of the ink-receiving layer is 4 g/m2 or more and 16 g/m2 or less per one surface in terms of a dry solid content.SELECTED DRAWING: None

Description

The present invention relates to an inkjet recording paper that is suitable for pigment inks in which the coloring material is a pigment and is suitable for labels having an adhesive layer.

An inkjet type image forming apparatus capable of printing on label paper using a water-based pigment ink is known (see, for example, Patent Document 1). Examples of label inkjet printing machines include Canon's label printer LX-P series, Seiko Epson's SurePress (registered trademark) series, Iwasaki Communication Equipment's LabelMeister (registered trademark) series, and SCREEN Graphic Solutions' Truepress. (Registered trademark) Jet series and the like exist.

As a recording medium, there is an inkjet recording medium for labels which has good ink absorption, high gloss, and excellent surface strength in printing with a line head type inkjet printer. For example, one or more coating layers are provided on one surface of the air-permeable support, the outermost layer thereof is a gloss-developing layer, and an adhesive layer is provided on the opposite surface, and the gloss-developing layer is an inorganic ultrafine particle. (A) A pearl necklace containing, which is pressed against a heated mirror roll while in a wet state to give a mirror gloss finish, and has (A) a major axis with an average secondary particle diameter of 30 to 500 nm. Label inkjet recording medium containing at least state colloidal silica, (B) monodisperse particle colloidal silica having an average primary particle size of 10 to 50 nm, and (C) alumina hydrate having an average primary particle size of 10 to 50 nm. Is known (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 10-100368 JP-A-2009-056753

The pigment ink for inkjet printing is an ink in which the coloring material is a pigment and the coloring material is dispersed in a medium such as water. Such pigment inks contain colorants (pigments), solvents (water in the case of water-based inks), anti-drying agents (oil components or solvents), penetrants and resins, and pH adjustments. Additives such as agents, surfactants, antioxidants and antibacterial agents are contained as needed.
For example, offset printing inks widely used in the printing industry include coloring materials (pigments) and vehicles (resins, vegetable oils, solvents), as well as defoamers, desiccants, desiccants, viscosity modifiers, etc. Additives such as dispersants and preservatives are included as needed.

Although the pigment ink for inkjet printing and the ink for offset printing differ in the quantitative balance of the composition, they are generally common in the coloring material, the solvent, the components related to drying, and the resin. In general, paper absorbs ink or ink due to the voids and capillarity present in the paper. The degree of voids and capillarity determines how much each of the above components is absorbed. The coloring material is absorbed inside the paper until the solvent and the solvent contained therein lose their fluidity due to evaporation and absorption into the paper. For example, if the coloring material is absorbed too much inside the paper, the color development property deteriorates. Further, if the solvent contained in the pigment ink and the solvent are not absorbed into the paper, the fluidity of the coloring material is not lost, and the paper cannot accept the coloring material well. Further, if the leveling of the color material cannot be achieved by the time the fluidity of the color material is lost, the glossiness of the printed portion is reduced to distortion. Further, if the antidrying agent, the penetrant and the resin contained in the pigment ink are not well absorbed by the paper, the glossiness of the printed portion increases with respect to the unprinted portion.

An inkjet recording paper having a glossy surface is still insufficient in terms of absorbency and color development property for pigment ink, especially for labels. Inkjet recording having an adhesive layer, good absorbency and color development to pigment ink, no distortion difference in glossiness between unprinted part and printed part, and glossy feeling in unprinted part and printed part. The appearance of paper is desired.

An object of the present invention is that the color material has good absorbency and color development property with respect to a pigment ink which is a pigment, there is no distorted difference in glossiness between the unprinted portion and the printed portion, and the unprinted portion and the printed portion are printed. It is to provide an inkjet recording paper which has a glossy feeling in a part and is suitable for a label.

The present inventors have focused on the fact that the components of the pigment ink for inkjet printing are generally the same in terms of the components as compared with the ink for offset printing, and use coated paper used for offset printing as the support of the inkjet recording paper. It was investigated. The coated paper used for offset printing is suitable for inks whose coloring material is a pigment. However, as is well known in the past, coated paper used for offset printing is poorly suitable for inkjet printing using pigment ink. This is because the pigment ink for inkjet printing has a negative charge for stabilizing the dispersion of the coloring material compared to the ink for offset printing, the content ratio of the resin as a dispersant is high, and the solvent such as antidrying agent. This is due to the high content ratio of the components. As a result of studies by the present inventors, the suitability for basic pigment inks is obtained by using the coated paper used for offset printing as a support, and specific ink acceptance is performed to compensate for the lack of suitability for pigment inks for inkjet printing. We have found a structure of an inkjet recording paper in which a layer is provided on a support.

An object of the present invention is achieved by:
[1] The support has an ink receiving layer on one side of the support, and an adhesive layer on the opposite side of the support from the side provided with the ink receiving layer, and the support is the Japanese economy and industry. It is a coated paper that is classified into the item "printing / information paper / coated printing paper / coated paper" in the ministry / production dynamic statistics survey / monthly paper report, and is located on the outermost side of the ink receiving layer with respect to the support. The ink receiving layer contains at least alumina hydrate, a binder, a cross-linking agent, an inorganic oxo acid and a wetting agent, and the amount of the ink receiving layer coated is 4 g / m ² or more and 16 g / m ² or less in terms of dry solid content per side. Inkjet recording paper.

[2] The inkjet recording paper according to the above [1], wherein the cross-linking agent is a boric acid compound or a borate compound.

[3] The inkjet recording paper according to the above [1] or the above [2], wherein the inorganic oxoacid is amide sulfuric acid.

[4] The inkjet recording paper according to any one of the above [1] to the above [3], wherein the wetting agent is an acetylene glycol-based surfactant.

According to the present invention, a label having good absorbency and color development property with respect to pigment ink, no distortion difference in glossiness between the unprinted portion and the printed portion, and glossiness in the unprinted portion and the printed portion. It is possible to provide an inkjet recording paper suitable for use.

Hereinafter, the inkjet recording paper of the present invention will be described in detail.

The inkjet recording paper has a support and an ink receiving layer on one side of the support. Further, the inkjet recording paper has an adhesive layer on the opposite surface of the support from the side provided with the ink receiving layer.

The support is coated paper classified into the items "printing / information paper / coated printing paper / coated paper / lightweight coated paper" in Japan's Ministry of Economy, Trade and Industry, Production Dynamics Statistics Survey, and monthly paper report. Such coated paper, coating weight combined both surfaces a coated paper in the range of less than 15 g / m ² or more 40 g / m ^2, for use in offset printing in the so-called paper wholesalers art for high quality paper " It is a coated paper called "A2 coated paper".

Among A2 coated papers, ISO8254-1: 2009 "Paper and board --- Measurement of specular gloss --- Part 1: 75 degree gloss with a combining beam, glossiness of 40% or less, and TAPPI method" A2 coated paper having a certain matte surface is preferable. The reason for this is that the absorbency of the inkjet recording paper for pigment ink is improved.

The ink receiving layer is provided on one side of the support by applying and drying the receiving layer coating liquid. The ink receiving layer is one layer or two or more layers. Among the ink receiving layers, the ink receiving layer located on the outermost side with respect to the support contains an alumina hydrate, a binder, a cross-linking agent, an inorganic oxo acid, and a wetting agent. When the ink receiving layer is one layer, the ink receiving layer contains an alumina hydrate, a binder, a cross-linking agent, an inorganic oxo acid, and a wetting agent. When there are two or more ink receiving layers, the ink receiving layer existing between the ink receiving layer located on the outermost side of the support and the support has the presence or absence of a white pigment, a binder, and various additives described later. In addition, there is no particular limitation on their types.

In the inkjet recording paper, the coating amount of the ink receiving layer is 4 g / m ² or more and 16 g / m ² or less. When there are two or more ink receiving layers, it is the total value of them. The ink receiving layer is preferably one layer from the viewpoint of manufacturing cost. If the coating amount of the ink receiving layer is less than 4 g / m ² or the coating amount of the ink receiving layer is more than 16 g / m ² , suitability for inkjet printing using pigment ink cannot be obtained.

The ink receiving layer located on the outermost side with respect to the support contains alumina hydrate, which is a kind of white pigment. Alumina hydrate has excellent absorbency of pigment ink containing a coloring material which is negatively charged because it has a positive charge. Further, since the alumina hydrate has transparency, the color development property of the pigment ink can be obtained. Further, the alumina hydrate has excellent light reflection, so that a glossy feeling of the unprinted portion can be obtained.
Alumina hydrate has a general formula:
Al ₂ O ₃ · nH ₂ O
Can be represented by. Alumina hydrates are classified into gypsite, vialite, norstrandite, boehmite, boehmite gel (pseudo-boehmite), diaspore, amorphous amorphous, etc. according to the difference in composition and crystal morphology. Among them, in the above formula, when the value of n is 1, it represents an alumina hydrate having a boehmite structure, and when n is more than 1 and less than 3, it represents an alumina hydrate having a pseudo-boehmite structure. 3 or more represents an alumina hydrate having an amorphous structure. The alumina hydrate is preferably an alumina hydrate having a pseudo-boehmite structure in which n is more than 1 and less than 3.

Alumina hydrate can be produced by known methods such as hydrolysis of aluminum alkoxide such as aluminum isopropoxide, neutralization of aluminum salt with alkali, and hydrolysis of aluminate. In addition, physical characteristics such as particle size, pore size, pore volume, and specific surface area of alumina hydrate should be controlled by conditions such as precipitation temperature, aging temperature, aging time, liquid pH, liquid concentration, and coexisting compounds. Can be done.

Examples of the method for producing an alumina hydrate from an alkoxide include JP-A-57-88074, JP-A-62-56321, JP-A-4-275917, JP-A-6-64918, and JP-A-7-10535. There is a method for hydrolyzing an aluminum alkoxide described in JP-A, No. 7-267633, US Pat. No. 2,656,321 and the like. Examples of these aluminum alkoxides include isopropoxide and 2-butoxide.

The ink receiving layer located on the outermost side with respect to the support can contain a white pigment conventionally known in the field of coated paper in addition to alumina hydrate. Examples of white pigments other than alumina hydrate include light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, and silicic acid. White inorganic pigments such as aluminum, activated white clay, diatomaceous clay, amorphous silica, colloidal silica, alumina, aluminum hydroxide, lithopone, zeolite, magnesium carbonate, magnesium hydroxide, styrene-based plastic pigments, acrylic-based plastic pigments, Examples thereof include white organic pigments such as polyethylene, microcapsules, urea resin, and melamine resin.
In the ink receiving layer located on the outermost side with respect to the support, it is preferable that the alumina hydrate accounts for 80% by mass or more with respect to the white pigment containing the alumina hydrate in the ink receiving layer.

The ink receiving layer located on the outermost side with respect to the support contains a binder. The binder is a water-dispersible binder or a water-soluble binder conventionally known in the field of coated paper. Examples of water-dispersible binders include conjugated diene copolymer latex such as styrene-butadiene copolymer or acrylonitrile-butadiene copolymer, acrylic acid ester or methacrylic acid ester polymer or methyl methacrylate-butadiene copolymer. Acrylic copolymer latex such as, ethylene-vinyl acetate copolymer, vinyl-based copolymer latex such as vinyl chloride-vinyl acetate copolymer, polyurethane resin latex, alkyd resin latex, unsaturated polyester resin latex, or these. Examples thereof include functional group-modified copolymer latex using a functional group-containing monomer such as a carboxyl group of various copolymers of the above, and heat-curable synthetic resins such as melamine resin and urea resin. Examples of water-soluble binders include starch derivatives such as oxidized starch, etherified starch and phosphoric acid esterified starch, cellulose derivatives such as methyl cellulose, carboxymethyl cellulose and hydroxyethyl cellulose, polyvinyl alcohol derivatives such as polyvinyl alcohol or silanol-modified polyvinyl alcohol, and Casein, gelatin or modifications thereof, soybean protein, purulan, arabic rubber, Karaya rubber, natural polymer resins such as albumin or derivatives thereof, vinyl polymers such as sodium polyacrylate, polyacrylamide, polyvinylpyrrolidone, sodium alginate, polypropylene Examples thereof include glycol, polyethylene glycol, maleic anhydride or a copolymer thereof. The binder is preferably one or more selected from the group consisting of these water-dispersible binders and water-soluble binders. The binder is more preferably polyvinyl alcohol or a derivative thereof from the viewpoint of reactivity with a cross-linking agent described later and transparency of the binder film.

The ink receiving layer located on the outermost side with respect to the support has a binder content of 100 parts by mass of a white pigment containing alumina hydrate in the ink receiving layer located on the outermost side with respect to the support. It is preferably 3 parts by mass or more and 12 parts by mass or less.

The ink receiving layer located on the outermost side with respect to the support contains a cross-linking agent. The cross-linking agent cross-links the binder. By containing the cross-linking agent, the ink receiving layer located on the outermost side with respect to the support can suppress cracks generated in the steps of applying and drying the ink receiving layer coating liquid. As a result, since it is possible to prevent the coloring material from falling into the cracks, the inkjet recording paper can obtain color development and / or glossiness of the printed portion.

Examples of cross-linking agents include boron compounds, formaldehyde, glioxal, succinaldehyde, glutaraldehyde, dialdehyde starch, aldehyde compounds such as dialdehyde derivatives of plant gums, diacetyl, 1,2-cyclopentandione, 3-hexene- Ketone compounds such as 2,5-dione, active halogen compounds such as bis (2-chloroethyl) urea, bis (2-chloroethyl) sulfone, 2,4-dichloro-6-hydroxy-s-triazine sodium salt, divinyl sulfone , 1,3-bis (vinylsulfonyl) -2-propanol, N, N'-ethylenebis (vinylsulfonylacetamide), divinylketone, 1,3-bis (acryloyl) urea, 1,3,5-tri Active vinyl compounds such as acryloyl-hexahydro-s-triazine, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, diglycerin polyglycidyl ether, spiroglycol diglycidyl ether, polyglycidyl ether of phenol resin, etc. Epoxy compounds, N-methylol compounds such as dimethylol urea and methylol dimethyl hydantin, melamine compounds such as trimethyl melamine, alkylated methylol melamine, benzoguanamine and melamine, isocyanate compounds such as 1,6-hexamethylene diisocyanate and xylylene diisocyanate, Aziridine compounds, carbodiimide compounds, ethyleneimino compounds such as 1,6-hexamethylene-N, N'-bisethyleneurea, halogenated carboxylaldehyde compounds such as mucochloric acid and mucophenokicyclolic acid, 2,3-dihydroxydioxane and the like. Dioxane compounds, titanium lactate, aluminum sulfate, polyaluminum chloride, chromium bright, potassium bright, metal-containing compounds such as zirconyl acetate and chromium acetate, polyamine compounds such as tetraethylenepentamine, hydrazide compounds such as dihydrazide adipate, and oxazoline. Examples thereof include low molecular weight or polymers containing two or more groups, anhydrides of polyhydric acids, acid chlorides, bissulfonate compounds, active ester compounds and the like. The cross-linking agent is preferably one or more selected from the group consisting of these. The cross-linking agent is more preferably a boron compound from the viewpoint of reactivity.

The boron compound is preferably a boric acid compound or a borate compound. Boric acid compound or a boric acid salt compound, for example, borax, boric acid, borates (eg, _{orthoborate, InBO 3, ScBO 3, YBO} 3, LaBO 3, Mg 3 (BO 3) 2, Co 3 (BO ₃ ) ₂ , diborate, eg Mg ₂ B ₂ O ₅ , Co ₂ B ₂ O ₅ , metaborate, eg LiBO ₂ , Ca (BO ₂ ) ₂ , NaBO ₂ , KBO ₂ , 4, borates, _{e.g., Na 2 B 4 O 7 ·} 10H 2 O, pentaborate, for _example, and the like _{KB 5 O 8 · 4H 2 O} ). The cross-linking agent is preferably one or more selected from the group consisting of borax, boric acid and orthoborate.

In the ink receiving layer located on the outermost side with respect to the support, the content of the cross-linking agent is 100 parts by mass of the white pigment containing alumina hydrate in the ink receiving layer located on the outermost side with respect to the support. It is preferably 0.5 parts by mass or more and 3 parts by mass or less.

The ink receiving layer located on the outermost side with respect to the support contains an inorganic oxoacid. By containing the inorganic oxo acid, the dispersibility of the alumina hydrate in the ink receiving layer coating liquid can be obtained. As a result, the inkjet printing paper can have good absorbency and color development of the pigment ink.
The inorganic oxoacid is an inorganic acid in which hydrogen, which can be dissociated as a proton, is bonded to an oxygen atom, and the central atom may be a non-metal or a metal. Examples of the inorganic oxo acid include phosphoric acid, amide sulfuric acid, nitric acid, sulfuric acid, silicic acid, carbonic acid, formic acid, tungstic acid, molybdenum acid, chromic acid, vanadic acid, perlenic acid, permanganic acid and the like. Boric acid contained in the cross-linking agent is excluded from the inorganic oxo acid. Further, the inorganic oxometalate may be a polyacid, and the polyacid may be an isopolyacid or a heteropolyacid.
The inorganic oxoacid is preferably one or more selected from the group consisting of these. The inorganic oxoacid is preferably amide sulfuric acid.

The ink receiving layer located on the outermost side with respect to the support has an inorganic oxoacid content of 100 parts by mass of a white pigment containing alumina hydrate in the ink receiving layer located on the outermost side with respect to the support. On the other hand, 0.5 parts by mass or more and 3 parts by mass or less are preferable.

The ink receiving layer located on the outermost side with respect to the support contains a wetting agent. By containing the wetting agent, the solvent contained in the pigment ink and the absorption of the solvent are improved. As a result, the inkjet recording paper can obtain the absorbency of the pigment ink. Further, the inkjet recording paper can have a glossy feeling in the printed portion.
The wetting agent is generally a variety of surfactants conventionally known as a wetting agent. Examples of the wetting agent include silicone-based surfactants, fluorine-based surfactants, acetylene glycol-based surfactants, alkylsulfosuccinates, alkylnaphthalene sulfonates, and the like. The wetting agent is preferably one or more selected from the group consisting of these. The wetting agent is more preferably an acetylene glycol-based surfactant.

The acetylene glycol-based surfactant is a compound represented by the following general formula (1) or (2).

R ₁ , R ₂ , R ₃ and R ₄ in the general formula (1) represent alkyl groups having 1 or more and 5 or less carbon atoms, respectively. It is preferable that R ₁ , R ₂ , R ₃ and R ₄ have a symmetrical structure centered on the acetylene group.

R ₅ , R ₆ , R ₇ and R ₈ in the general formula (2) represent alkyl groups having 1 or more and 5 or less carbon atoms, respectively. m and n are integers of 1 or more and 25 or less, respectively, and m + n is 2 or more and 40 or less. OE oxyethylene chain _{(-O-CH 2 -CH 2 -} ), OP is an oxypropylene chain _{(-O-CH 2 -CH [CH} 3] -) is. OE and OP may be single chains or mixed chains, respectively. It is preferable that R ₅ , R ₆ , R ₇ and R ₈ have a symmetrical structure centered on the acetylene group.

The acetylene glycol-based surfactant is commercially available from Nissin Chemical Industry Co., Ltd. under the name of "Surfynol (registered trademark)" or "Olfine (registered trademark)" and by Kawaken Fine Chemical Co., Ltd. under the name of "Acetylenel (registered trademark)". To.

The acetylene glycol-based surfactant is 2,4,7,9-tetramethyl-5-decine-4,7-diol or 2,4,7,9-tetramethyl-5-decine-4,7-diol. Ethoxylate is preferred. The reason for this is that it is commercially available.

The ink receiving layer located on the outermost side of the support has a wetting agent content of 100 parts by mass of a white pigment containing alumina hydrate in the ink receiving layer located on the outermost side of the support. It is preferably 0.01 part by mass or more and 0.3 part by mass or less.

The ink receiving layer may be provided with various additives commonly used in the papermaking field, such as dye fixers, pigment dispersants, thickeners, fluidity improvers, defoamers, defoamers, and defoamers, if necessary. Molding agents, foaming agents, penetrants, ultraviolet absorbers, antioxidants, preservatives, antibacterial agents, water resistant agents, wet paper strength enhancers, dry paper strength enhancers and the like can be appropriately contained.

In the present invention, as a method of providing the ink receiving layer on the support, for example, a method of coating and drying the ink receiving layer coating liquid on the support using a conventionally known coating device and drying device can be mentioned. it can. Examples of the coating apparatus include a size press, a gate roll coater, a film transfer coater, a blade coater, a rod coater, an air knife coater, a comma coater, a gravure coater, a bar coater, an E bar coater, a curtain coater and the like. Examples of drying devices include hot air dryers such as straight tunnel dryers, arch dryers, air loop dryers, and sine curve air float dryers, infrared heating dryers, and various drying devices such as dryers using microwaves. Can be done. Further, the ink receiving layer can be finished by using a calendar device such as a machine calendar, a TG calendar, a super calendar, or a soft calendar.

The inkjet recording paper has an adhesive layer on the opposite side of the support from the side provided with the ink receiving layer. The adhesive layer is conventionally known in the field of label paper. After forming the ink receiving layer, the adhesive layer is preferably provided on the opposite surface of the support from the side on which the ink receiving layer is provided.

The adhesive layer is, for example, a press roll in which an adhesive is applied to the release agent-coated surface of the release paper described later, and the obtained adhesive layer is laminated on the surface opposite to the side on which the ink receiving layer of the paper is provided. It can be provided on the recording paper by a method of crimping with or the like. Alternatively, the adhesive layer can be provided on the recording paper by first applying an adhesive on the surface of the recording paper opposite to the side on which the ink receiving layer is provided and then adhering it to the release paper.

The pressure-sensitive adhesive is conventionally known and is not particularly limited. Examples of the pressure-sensitive adhesive include rubber-based pressure-sensitive adhesives and acrylic resin-based pressure-sensitive adhesives. Examples of the rubber-based pressure-sensitive adhesive include natural rubber and styrene-butadiene rubber. Further, as an example of the acrylic resin-based pressure-sensitive adhesive, a resin obtained by polymerizing an acrylic monomer such as 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate, acrylic acid, and β-hydroxyethyl acrylate can be mentioned.

Further, in order to improve physical properties such as heat resistance or solvent resistance of the pressure-sensitive adhesive, the pressure-sensitive adhesive layer can be subjected to a cross-linking reaction by an isocyanate type, a melamine type, a metal chelate type or the like. In addition, the adhesive layer includes light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, active white clay, diatomaceous clay, etc. White inorganic pigments such as silica, alumina, aluminum hydroxide, lithopone, zeolite, magnesium carbonate, magnesium hydroxide, styrene plastic pigments, acrylic plastic pigments, polyethylene, microcapsules, urea resin, melamine resin and other white organic pigments Can be contained. The adhesive layer includes water-soluble polymers, petroleum-based resins, various paraffin waxes, fatty acids or derivatives thereof, higher alcohols, metal soaps, silicones, antistatic agents, thickeners, dispersants, preservatives, and oxidations. It can contain an inhibitor, an antifoaming agent, and the like.

The device for applying the pressure-sensitive adhesive is a conventionally known method and is not particularly limited. Examples of devices for applying adhesives include air knife coaters, blade coaters, bar coaters, roll coaters, slot nozzles, slot dies, rotary screen printers, gravure coaters, offset gravure coaters, hot melt wheels, spiral sprays, etc. be able to.

The release paper is conventionally known and is not particularly limited. Release paper generally consists of a substrate and a release agent. Examples of the base material include high-quality paper, kraft paper, glassine paper, laminated paper, plastic film and the like. Examples of the release agent on the base material include silicone resin and the like.

The inkjet recording medium for the label may be in a state in which the release paper is attached to the adhesive layer before the label is attached to the object.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded. Moreover, the mass part and mass% shown in an Example show the value of a dry solid content or a substantial component.

<Preparation of ink receiving layer coating liquid>
The ink receiving layer coating liquid was prepared with the following composition.
White pigment (types are listed in Table 1) Number of parts by mass is shown in Table 1 Binder (Kuraray, Kuraray Poval 95-88) 8 parts by mass Crosslinker (types are listed in Table 1) 1.5 parts by mass Inorganic oxoacid ( (Types are listed in Table 1) 1.5 parts by mass Wetting agent (Types are listed in Table 1) 0.05 parts by mass With the above contents, water is mixed and dispersed in a medium to adjust the solid content concentration to 20% by mass. did.
When the white pigment was alumina hydrate, 1 part of acetic acid was mixed with 100 parts of alumina hydrate to prepare a preliminary dispersion, and a coating liquid was prepared using the dispersion.

For white pigments
Alumina hydrate: Sasol, Disperal® HP14
Amorphous silica: Oriental Silicas, Inc.
Fine Seal (registered trademark) X37B
Colloidal silica: Grace Japan, Ludox (registered trademark) CL-P
Heavy Calcium Carbonate: Phymatec, FMT-90
Was used.

For wetting agents,
A: Nisshin Kagaku Kogyo Co., Ltd., Surfynol 104E, structure of general formula (1) B: Nisshin Kagaku Kogyo Co., Ltd., Olfine E1010, structure of general formula (2) C: Dai-ichi Kogyo Seiyaku Co., Ltd., Neocol (registered trademark) YSK
(Alkylsulfosuccinic acid derivative)
Was used.

<Coating and drying the ink receiving layer>
The ink receiving layer coating liquid is applied and dried with an air knife coater on one side of the support so that the coating amount is ^{2, 4} , 7, 16 and 20 g / m ^2, and then calendar processing is applied. An ink receiving layer was provided on the support. The amount of each coating is shown in Table 1.

The following A2 coated paper was used for the supports 1 and 2.
Support 1: Mitsubishi Paper Mills Pearl Coat (registered trademark) N (basis weight 84.9 g / m ² , glossiness about 67%)
Support 2: Mitsubishi Paper Mills New V Mat (registered trademark) (basis weight 81.4 g / m ² , glossiness about 31%)
The following paper was used for the support 3.

<Support 3>
80 parts by mass of LBKP (filtered water degree 370 mlcsf) and 20 parts by mass of NBKP (filtered water degree 400 mlcsf), 13 parts by mass of talc, 3 parts by mass of sulfuric acid band, 0.2 parts by mass of commercially available rosin sizing agent, 0.3 parts by mass of cationic starch Was mixed with water to prepare a paper material having a concentration of 1% by mass. The paper material was made with a long net paper machine so that the basis weight was 80 g / m ² . After the papermaking, the support 3 was manufactured by adhering 2 g / m ² of oxidized starch per side with a solid content using a size press device.

<Adhesive layer>
A commercially available silicone resin was applied to glassine paper at a rate of 1 g / m ² with a gravure coater. A water-based acrylic resin-based pressure-sensitive adhesive was applied to the surface side of the glassine paper coated with the silicone resin so that the coating amount was 10 g / m ^{2 in} terms of dry solid content. The surface of the glassine paper coated with the adhesive and the surface of the coated paper opposite to the side of the coated paper provided with the ink receiving layer are opposed to each other and bonded with a press roll to the surface opposite to the side of the coated paper provided with the ink receiving layer. An inkjet recording paper having an adhesive layer was obtained.

The following items were evaluated for the obtained inkjet recording paper.

<Absorption of pigment ink>
For absorbency, a solid image of each color was printed using an inkjet label printer LX-P1500 (Canon) equipped with pigment ink. With respect to the inkjet recording paper discharged from the outlet of the printer main body, 5 minutes after printing, the printed portion was rubbed with absorbent cotton, and the coloring of the absorbent cotton due to the transfer of the coloring material to the absorbent cotton was visually observed and evaluated according to the following criteria. In the present invention, the inkjet recording paper is considered to have good absorbency to pigment ink if it is evaluated as A or B.
A: No coloring was observed and it was good.
B: Coloring is very slight, but generally good.
C: Slight coloring is observed, but it is practical.
D: Coloring is observed and it is not practical.

<Color development of pigment ink>
For color development, a solid image of each color was printed using an inkjet label printer LX-P1500 (Canon) equipped with pigment ink. With respect to the inkjet recording paper discharged from the outlet of the main body, 5 minutes after printing, the printed portion of each color solid image was visually observed from the viewpoint of color density and vividness, and evaluated according to the following criteria. In the present invention, the inkjet recording paper is considered to have good color development property with respect to the pigment ink if it is evaluated as A or B.
A: Good.
B: Although it is inferior to the above "A", it is generally good.
C: Although inferior to the above "B", it is practical.
D: Inferior to the above "C" and impractical.

<Glossy feeling of unprinted part>
The glossiness of the unprinted portion was evaluated by measuring the glossiness of 75 degrees for the unprinted portion of the inkjet recording paper. The 75 degree glossiness was measured using a digital gloss meter (GM-26D type [75 degree-75 degree], Murakami Color Technology Laboratory Co., Ltd.) according to ISO8254-1: 2009. The glossiness of the unprinted portion was evaluated from the value of the 75 degree glossiness according to the following criteria in consideration of the glossiness of the printed portion. In the present invention, if the evaluation of A, the inkjet recording paper has a glossy feeling in the unprinted portion.
A: Blank paper glossiness is 50% or more.
B: Blank paper glossiness is less than 50%.

<Glossiness of the printed part>
The glossiness of the printed portion was evaluated by measuring the difference in the glossiness of the printed portion by 75 degrees with respect to the unprinted portion of the inkjet recording paper. A solid image of each color was printed using an inkjet label printer LX-P1500 (Canon) equipped with pigment ink. The glossiness of 75 degrees was measured 5 minutes after printing on the printed portion of each color solid image of the inkjet recording paper discharged from the outlet of the main body. The 75 degree glossiness was measured according to ISO8254-1 using a digital glossometer (GM-26D type [75 degree-75 degree], Murakami Color Technology Laboratory Co., Ltd.).
The glossiness of the printed portion was evaluated as a difference in glossiness with respect to the unprinted portion by a method of measuring a 75-degree glossiness difference between the printed portion and the unprinted portion of each color solid image. The 75 degree glossiness was measured using a digital gloss meter (GM-26D type [75 degree-75 degree], Murakami Color Technology Laboratory Co., Ltd.) according to ISO8254-1: 2009. Mean value of glossiness difference obtained by subtracting glossiness of unprinted part from glossiness of printed part of solid image = ([Black Δ gloss] + [Cyan Δ gloss] + [Magenta Δ gloss] + [Yellow Δ gloss]) / 4 was calculated and evaluated according to the following criteria. In the present invention, if the evaluation is A, B or C, the inkjet recording paper has a glossy feeling without any distortion difference in the glossy feeling of the printed portion with respect to the glossy feeling of the unprinted portion.
A: The average glossiness difference is -2.5 or more and 5 or less.
B: The average glossiness difference is -5 or more and 7.5 or less, excluding the range of A above.
C: The average glossiness difference is -7.5 or more and 10 or less, excluding the ranges A and B above.
D: The average glossiness difference is less than -7.5 or more than 10.

The evaluation results are shown in Table 1.

From Table 1, the inkjet recording papers of Examples 1 to 11 corresponding to the present invention have good absorbency and color development property with respect to the pigment ink, and there is a distorted difference in glossiness between the unprinted portion and the printed portion. It can be seen that the unprinted portion and the printed portion have a glossy feeling. On the other hand, it can be seen that the inkjet recording papers of Comparative Examples 1 to 9 that do not satisfy the configuration of the present invention cannot satisfy at least one of the effects of the present invention.
Mainly, from the comparison of Examples 2, 4 and 5, it can be seen that the cross-linking agent is preferably a boric acid compound or a borate compound. Further, it can be seen that the inorganic oxoacid is preferably amide sulfuric acid mainly from the comparison of Examples 2, 6 and 7. Further, mainly from the comparison of Examples 2, 8 and 9, it can be seen that the wetting agent is preferably an acetylene glycol-based surfactant.

Claims (4)

It has a support, an ink receiving layer on one side of the support, and an adhesive layer on the opposite side of the support to the side where the ink receiving layer is provided, and the support is produced by the Ministry of Economy, Trade and Industry of Japan. It is a coated paper classified into the item "printing / information paper / coated printing paper / coated paper" in the dynamic statistics survey / monthly paper report, and the ink receiving layer located on the outermost side of the ink receiving layer with respect to the support. Contains at least an alumina hydrate, a binder, a cross-linking agent, an inorganic oxo acid, and a wetting agent, and the coating amount of the ink receiving layer is 4 g / m ² or more and 16 g / m ² or less in terms of dry solid content per side. Recording sheet. The inkjet recording paper according to claim 1, wherein the cross-linking agent is a boric acid compound or a borate compound. The inkjet recording paper according to claim 1 or 2, wherein the inorganic oxo acid is amide sulfuric acid. The inkjet recording paper according to any one of claims 1 to 3, wherein the wetting agent is an acetylene glycol-based surfactant.