JP2016180033A - Ink composition for aqueous inkjet ink for pressure-sensitive adhesive layer of re-releasable pressure-bonded recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition for an aqueous inkjet ink for a pressure-sensitive adhesive layer of re-releasable pressure-bonded recording paper which is excellent in peeling resistance of printing and also in discharge stability of ink, and has base paper and a pressure-sensitive adhesive layer.SOLUTION: There is provided an ink composition for an aqueous inkjet ink which contains an anionic group-containing resin coating pigment, emulsion, a water-soluble solvent and water, where a glass transition temperature of a resin of the emulsion is -30°C to 30°C, a ratio of a resin solid content of the emulsion in the ink composition for the aqueous inkjet ink is 0.7-7 mass%, and a ratio of the water soluble solvent is 25-55 mass%.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous ink-jet ink composition used for a pressure-sensitive adhesive layer of a releasable pressure-sensitive recording sheet such as a bonded postcard.

  Conventionally, releasable pressure-sensitive recording paper such as bonded postcards, which is easy to peel off but difficult to reattach, has been used in order to more easily convey confidential and confidential information to only the recipient. Has been. Re-peelable pressure-sensitive recording paper is a pressure-sensitive adhesive layer that shows neither adhesiveness nor adhesiveness under normal conditions, but exhibits adhesiveness when pressed and can be peeled after pressure bonding (hereinafter referred to as pressure bonding). , Paper provided on the base paper.

  Examples of a method for producing a bonded postcard include a front paste type and a post paste type. The pre-glue-type bonded postcard is a paper manufacturer that forms a pressure-sensitive adhesive layer on the base paper used for the postcard by applying and drying a pressure-sensitive adhesive in advance, such as an inkjet or electrophotographic system. Using a printer, the ink is printed on the surface of the pressure-sensitive adhesive layer, and then it is manufactured by pressure bonding. On the other hand, the post-glue-type bonded postcard is printed on the base paper using a printer such as an inkjet or electrophotographic method, and after applying and drying a pressure-sensitive adhesive so as to cover the printing surface, It is produced by performing a crimping process.

  In general, with a pre-adhesive bonded postcard, ink droplets that have landed on the pressure-sensitive adhesive layer surface tend to remain on the surface without being absorbed by the pressure-sensitive adhesive layer. Easy to stick. As a result, when the bonded postcard is peeled off, the ink may transfer from one printed surface to the other printed surface, which may impair the design as a printed matter or the information transmission as a postal matter. . These are said to have poor peel resistance on printed matter.

  In addition, in the ink composition for water-based inkjet, the ink remaining inside the nozzles of the printer tends to be fused and solidified easily. If the solidified ink accumulates in the nozzle, the flying trajectory of the ink ejected thereafter becomes unstable, resulting in poor printing and image formation. In particular, when an emulsion is used as the binder resin of the ink composition, the re-solubility of the solidified ink becomes low, and solidification inside the nozzle becomes a serious problem.

  As the pressure sensitive adhesive layer for the pre-glue type, for example, various improved methods as disclosed in Patent Documents 1 to 3 have been proposed.

JP 2008-45115 A JP 2009-119772 A JP 2012-025075 A

  However, even in the method for improving the pressure-sensitive adhesive layer for the pre-adhesive disclosed in Patent Documents 1 to 3, the pressure-sensitive adhesive of the releasable pressure-sensitive recording sheet that achieves both the printing peeling resistance and the ink ejection stability. Currently, it is difficult to obtain a water-based inkjet ink composition for a layer.

  The present invention relates to a water-based inkjet ink composition for a pressure-sensitive adhesive layer of a releasable pressure-sensitive adhesive recording sheet having a base paper and a pressure-sensitive adhesive layer, which has excellent print peeling resistance and excellent ink ejection stability. The purpose is to provide.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that an aqueous inkjet ink composition for a pressure-sensitive adhesive layer of a releasable pressure-sensitive recording sheet having the following base paper and pressure-sensitive adhesive layer: Invented the product.

  That is, the present invention is an aqueous inkjet ink composition containing an anionic group-containing resin-coated pigment, an emulsion, a water-soluble solvent, and water, and the glass transition temperature of the resin of the emulsion is −30 ° C. to 30 ° C. A base paper and a feeling that the resin solid content of the emulsion in the water-based inkjet ink composition is 0.7 to 7% by mass and the water-soluble solvent is 25 to 55% by mass. The present invention relates to an aqueous inkjet ink composition for a pressure-sensitive adhesive layer of a releasable pressure-sensitive recording sheet having a pressure adhesive layer.

  In the water-based inkjet ink composition for a pressure-sensitive adhesive layer of a releasable pressure-sensitive adhesive recording sheet having a base paper and a pressure-sensitive adhesive layer of the present invention, the emulsion is an acrylic resin emulsion and / or a styrene-acrylic type. A resin emulsion is preferred.

  An aqueous inkjet ink composition for a pressure-sensitive adhesive layer of a releasable pressure-sensitive adhesive recording paper having a base paper and a pressure-sensitive adhesive layer of the present invention, wherein the water-soluble solvent is propylene glycol, glycerin, diethylene glycol, ethylene glycol It is preferably at least one selected from the group consisting of monobutyl ether and diethylene glycol monobutyl ether.

  The present invention prints a water-based inkjet ink composition for a pressure-sensitive adhesive layer of a releasable pressure-sensitive adhesive recording paper having a base paper and a pressure-sensitive adhesive layer on the pressure-sensitive adhesive layer of the releasable pressure-sensitive adhesive recording paper. It is related with the releasable pressure-sensitive recording paper printed matter obtained in this way.

  According to the water-based inkjet ink composition of the present invention, since the print printed on the pressure-sensitive adhesive layer of the releasable pressure-sensitive adhesive recording paper having the base paper and the pressure-sensitive adhesive layer is excellent in peeling resistance, Sensitivity of a releasable pressure-sensitive recording paper having a base paper and a pressure-sensitive adhesive layer, which has an effect of preventing transfer and excellent discharge stability of the ink composition, and thus has a good coating stability effect. An aqueous inkjet ink composition for a pressure-sensitive adhesive layer can be provided.

  The expression mechanism of the effect of the present invention is not clear, but is estimated as follows.

  In an aqueous inkjet ink composition containing an anionic group-containing resin-coated pigment, an emulsion, a water-soluble solvent, and water, a specific amount of emulsion resin having a glass transition temperature of −30 ° C. to 30 ° C. is used. By using this water-soluble solvent, the ink droplets that land on the pressure-sensitive adhesive layer of the releasable pressure-sensitive adhesive recording paper having the base paper and the pressure-sensitive adhesive layer do not remain on the surface of the pressure-sensitive adhesive layer. It is presumed that it is absorbed efficiently by the pressure-sensitive adhesive layer, and as a result, the prints do not stick to each other when the paper is pressure-bonded, and therefore, good print peeling resistance is exhibited. Further, in the above composition, since the emulsion having a specific glass transition temperature is hard to break and fuse within the nozzle of the printer, the ink does not solidify inside the nozzle and expresses good ink ejection stability. It is estimated to be.

An aqueous inkjet ink composition for a pressure-sensitive adhesive layer of a releasable pressure-sensitive adhesive recording paper having a base paper and a pressure-sensitive adhesive layer of the present invention comprises an anionic group-containing resin-coated pigment, an emulsion, a water-soluble solvent, and Contains water.
Hereinafter, each component contained in the water-based inkjet ink composition for the pressure-sensitive adhesive layer of the releasable pressure-sensitive adhesive recording paper having the base paper and the pressure-sensitive adhesive layer of the present invention will be described.

<Anionic group-containing resin-coated pigment>
The anionic group-containing resin-coated pigment of the present invention is a pigment coated with an anionic group-containing resin.

<Pigment>
Although it does not specifically limit as a pigment of this invention, The various inorganic pigment and organic pigment which are generally used with an inkjet recording liquid can be mentioned. Examples of the inorganic pigment include carbon black, titanium black, titanium white, zinc sulfide, and bengara. Examples of the organic pigment include quinacridone pigment, dioxazine pigment, phthalocyanine pigment, anthrapyrimidine pigment, ansan Throne pigment, Indanthrone pigment, Flavanthrone pigment, Perylene pigment, Diketopyrrolopyrrole pigment, Perinone pigment, Quinophthalone pigment, Anthraquinone pigment, Thioindigo pigment, Benzimidazolone pigment, Isoindo Examples thereof include linone pigments, azomethine pigments, and azo pigments. At least one type of pigment may be used, and two or more types may be used in combination.

<Anionic group-containing resin>
The anionic group-containing resin of the present invention is an anionic group-containing resin that can be used for dispersing pigments in ordinary inks or paints or as a binder, and can be dissolved in an aqueous medium in the presence of a basic compound. Although there is no particular limitation, a resin containing one or more anionic groups such as a carboxyl group, a sulfonic acid group, and a phosphono group (—P (═O) (OH ₂ )) is preferable.

  The anionic group-containing resin further comprises a hydrophobic part mainly for improving the adsorptivity with the pigment and / or a hydrophilic part mainly for obtaining an action effective for preventing aggregation in an aqueous medium. Is preferably included in the molecule. Examples of the hydrophobic moiety to be introduced into the molecule include hydrophobic groups such as a long-chain alkyl group, an alicyclic or aromatic cyclic hydrocarbon group, and the hydrophilic moiety to be introduced into the molecule includes (poly) Examples include hydrophilic groups such as oxyalkylene chains, basic nitrogen-containing groups, hydroxyl groups, and epoxy groups.

  The acid value of the anionic group-containing resin is preferably 40 mgKOH / g or more, and more preferably 70 mgKOH / g or more, from the viewpoint of enhancing the dispersion stability of the dispersion of the anionic group-containing resin-coated pigment. The acid value of the anionic group-containing resin is 350 mgKOH / g or less from the viewpoint of suppressing the hydrophilicity of the anionic group-containing resin, increasing the storage stability of the anionic group-containing resin-coated pigment, and increasing the water resistance of the printed matter. Is preferable, and 300 mgKOH / g or less is more preferable.

  The acid value is calculated based on the number of potassium hydroxide theoretically required to neutralize 1 g of the anionic group-containing resin based on the composition of the monomer used to synthesize the anionic group-containing resin. The calculated theoretical acid value.

  The glass transition temperature of the anionic group-containing resin is preferably 0 ° C. or higher, more preferably 50 ° C. or higher, from the viewpoint of easy handling of the resin-coated pigment. The glass transition temperature of the anionic group-containing resin is preferably 150 ° C. or lower, and more preferably 120 ° C. or lower, from the viewpoint of easy handling during resin synthesis.

When the anionic group-containing resin is an acrylic copolymer resin, the glass transition temperature of the anionic group-containing resin is a theoretical glass transition temperature obtained by the following formula of wood.
Wood formula: 1 / Tg = W1 / Tg1 + W2 / Tg2 + W3 / Tg3 +... + Wx / Tgx
[Wherein, Tg1 to Tgx are the glass transition temperatures of the respective homopolymers of monomers 1, 2, 3,... X constituting the anionic group-containing resin, and W1 to Wx are monomers 1, 2, 3... Each polymerization fraction of x, Tg represents the theoretical glass transition temperature. However, the glass transition temperature in the wood equation is an absolute temperature. ]
The glass transition temperature of the anionic group-containing resin is a theoretical glass transition temperature obtained by thermal analysis when the anionic group-containing resin is other than an acrylic copolymer resin. As a thermal analysis method, in accordance with JIS K7121 (plastic transition temperature measurement method), as an example, a Pyris1 DSC manufactured by PerkinElmer Co., Ltd. is used, with a temperature rising rate of 20 ° C./min and a nitrogen gas flow rate of 20 ml / min. The glass transition temperature can be measured below.

  The weight average molecular weight of the anionic group-containing resin is preferably 3,000 or more, and more preferably 7,000 or more, from the viewpoint of enhancing the dispersion stability of the aqueous dispersion of the anionic group-containing resin-coated pigment. The weight average molecular weight of the anionic group-containing resin is preferably 200,000 or less, and more preferably 100,000 or less, from the viewpoint of enhancing the solubility in an aqueous medium.

  The weight average molecular weight can be measured by a gel permeation chromatography (GPC) method. As an example, Water 2690 (manufactured by Waters) as a GPC apparatus, PLgel 5μ, MIXED-D (manufactured by Polymer Laboratories) as a column, tetrahydrofuran as a developing solvent, column temperature 25 ° C., flow rate 1 ml / min, RI Chromatography is performed under conditions of a detector, a sample injection concentration of 10 milligrams / milliliter, and an injection amount of 100 microliters, and the weight average molecular weight in terms of polystyrene can be obtained.

  Examples of the anionic group-containing resin include an acrylic copolymer resin, a maleic acid copolymer resin, a polyester resin obtained by a condensation polymerization reaction, and a polyurethane resin. A material for synthesizing such an anionic group-containing resin is disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-94825, and an acrylic copolymer obtained by using the material described in the publication. Resins, maleic acid copolymer resins, polyester resins, polyurethane resins and the like can be used. Furthermore, of course, resins obtained using other materials can also be used. At least one kind of anionic group-containing resin may be used, and two or more kinds may be used in combination.

  As the acrylic copolymer resin, for example, a mixture of other monomers copolymerizable with an anionic group-containing monomer is used as a normal radical generator (for example, benzoyl peroxide, tertiary butyl peroxybenzoate, Those obtained by polymerization in a solvent in the presence of azobisisobutyronitrile and the like) can be used.

  Examples of the anionic group-containing monomer include monomers having at least one anionic group selected from the group consisting of a carboxyl group, a sulfonic acid group, and a phosphono group. The monomer having is particularly preferred.

  Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, 2-carboxyethyl (meth) acrylate, 2-carboxypropyl (meth) acrylate, and anhydrous. Maleic acid, fumaric anhydride, maleic acid half ester, etc. are mentioned.

  Examples of the monomer having a sulfonic acid group include sulfoethyl methacrylate.

  Examples of the monomer having a phosphono group include phosphonoethyl methacrylate.

  The other monomer copolymerizable with the anion group-containing monomer preferably includes a hydrophobic group-containing monomer from the viewpoint of improving the adsorptivity with the pigment.

  Examples of the hydrophobic group-containing monomer include, as monomers having a long-chain alkyl group, alkyl esters having a radical polymerizable unsaturated carboxylic acid such as (meth) acrylic acid having 8 or more carbon atoms (for example, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, 2-hydroxystearyl (meth) acrylate, etc.), alkyl vinyl ethers having 8 or more carbon atoms (for example, Dodecyl vinyl ether, etc.), vinyl esters of fatty acids having 8 or more carbon atoms (for example, vinyl 2-ethylhexanoate, vinyl laurate, vinyl stearate, etc.); as a monomer having an alicyclic hydrocarbon group, Cyclohexyl (meth) acrylate, etc .; having aromatic hydrocarbon group As mer, benzyl (meth) acrylate, styrene, alpha-styrene, and the like styrenic monomers such as vinyl toluene.

  The other monomer copolymerizable with the anionic group-containing monomer preferably includes a hydrophilic group-containing monomer from the viewpoint of suppressing aggregation of the anionic group-containing resin in the aqueous medium. .

  Examples of the hydrophilic group-containing monomer include methoxy polyethylene glycol, methoxy polyethylene polypropylene glycol, ethoxy polyethylene glycol, ethoxy polyethylene polypropylene glycol, propoxy polyethylene glycol, and propoxy polyethylene as monomers having a (poly) oxyalkylene chain. One-terminal alkyl-capped (poly) alkylene glycols such as polypropylene glycol and esterified products of radically polymerizable unsaturated carboxylic acids such as (meth) acrylic acid, and radically polymerizable unsaturated carboxylic acids such as (meth) acrylic acid Ethylene oxide adduct and / or propylene oxide adduct, etc .; basic group-containing monomers such as 1-vinyl-2-pyrrolidone and 1-vinyl-3-pyrrolidone Nylpyrrolidones, 2-vinylpyridine, 4-vinylpyridine, 5-methyl-2-vinylpyridine, vinylpyridines such as 5-ethyl-2-vinylpyridine, 1-vinylimidazole, 1-vinyl-2-methylimidazole Vinyl imidazoles such as 3-vinyl piperidine, vinyl biperidines such as N-methyl-3-vinyl piperidine, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, tert-butylaminoethyl (meth) acrylate, (Meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-methoxy (meth) acrylamide, N-ethoxy (meth) acrylamide, N-dimethylacrylamide, N-propylacrylamido Nitrogen-containing derivatives of (meth) acrylic acid such as; monomers having a hydroxyl group, for example, hydroxyalkyl esters of (meth) acrylic acid such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, etc. ; As a monomer which has an epoxy group, glycidyl (meth) acrylate etc. are mentioned, for example.

  Examples of other copolymerizable monomers other than the hydrophobic group-containing monomer and the hydrophilic group-containing monomer include methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. , (Meth) acrylic acid isopropyl, (meth) acrylic acid butyl, (meth) acrylic acid hexyl and other (meth) acrylic acid alkyl esters having less than 8 carbon atoms.

  The content of the anionic group-containing resin in the anionic group-containing resin-coated pigment is 10 parts by mass with respect to 100 parts by mass of the pigment from the viewpoint of enhancing the dispersion stability of the dispersion of the anionic group-containing resin-coated pigment. The above is preferable, 20 parts by mass or more is more preferable, and 30 parts by mass or more is more preferable. The content of the anionic group-containing resin is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, from the viewpoint of reducing the viscosity of the aqueous inkjet composition of the present invention with respect to 100 parts by mass of the pigment. 60 parts by mass or less is more preferable.

<Method of coating pigment with anionic group-containing resin>
The anionic group-containing resin-coated pigment of the present invention is obtained by dissolving the anionic group-containing resin in an aqueous medium in the presence of a basic compound, and then adding the pigment, and using a dispersing machine such as a mill-type dispersing machine or a high-pressure dispersing machine. A pigment dispersion (also referred to as an ink base precursor) is obtained, diluted as necessary, and the basic compound is removed by an acid precipitation method or an ion exchange means.

<Basic compound>
Examples of the basic compound include inorganic basic compounds such as sodium hydroxide and potassium hydroxide, ammonia, methylamine, ethylamine, monoethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, Examples thereof include organic basic compounds such as N, N-dibutylethanolamine, diethanolamine, N-methyldiethanolamine, triethanolamine, morpholine, N-methylmorpholine and N-ethylmorpholine. These basic compounds can be used alone or in admixture of two or more. Among these, alkanolamines such as monoethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanolamine, diethanolamine, N-methyldiethanolamine, and triethanolamine are preferable from the viewpoint of pigment dispersion. Is preferred.

  The basic compound may be used in an amount that dissolves the anionic group-containing resin in the aqueous medium, but is usually used in the range of 40 to 100% of the amount capable of neutralizing the anionic group-containing resin. . From the viewpoint of enhancing the dispersion stability of the resin-coated pigment and the water resistance of the printed material, it is preferably used at 50 to 90%. Of course, it can be used in an amount exceeding this range.

<Aqueous medium>
As the aqueous medium, water or a mixture of water and a water-miscible organic solvent can be used. Examples of the water-miscible organic solvent include lower alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol and n-propyl alcohol, polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol and glycerin, ethylene (Poly) alkylene glycol monoalkyl ethers such as glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monoacetate, propylene glycol mono Mono-fats of (poly) alkylene glycols such as acetate Such as acid esters. Water-miscible organic solvents can be used alone or in admixture of two or more.

  The amount of the aqueous medium used is preferably 500 parts by mass or more and more preferably 1000 parts by mass or more from the viewpoint of increasing the solubility of the anionic group-containing resin with respect to 100 parts by mass of the anionic group-containing resin. The amount of the aqueous medium used is preferably 4000 parts by mass or less and more preferably 3000 parts by mass or less from the viewpoint of increasing the viscosity at the time of dispersion of the resin-coated pigment with respect to 100 parts by mass of the anionic group-containing resin.

<Acid deposition method>
As the acid precipitation method, an acidic compound such as hydrochloric acid or acetic acid is added to the pigment dispersion, and the pH is neutral or acidic, thereby removing the basic compound and depositing the anionic group-containing resin on the pigment surface. The method of (coating) is mentioned.

  The pigment coated with the anionic group-containing resin obtained by the acid precipitation method settles in the system or becomes a paste. An anionic group-containing resin-coated pigment can be obtained by filtering, washing with water, and drying if necessary. This anionic group-containing resin-coated pigment can be used in the form of a water-containing cake or in a dried state.

<Ion exchange means>
As the ion exchange means, a method in which an ion exchanger is directly added to the pigment dispersion, or a method in which the pigment dispersion is passed through an ion exchange column filled with an ion exchanger, a cation of a basic compound and hydrogen is used. There is a method of performing ion exchange, thereby precipitating (coating) an anionic group-containing resin on the pigment surface.

  As said ion exchanger, an organic ion exchanger, an inorganic ion exchanger, and these combination can be used. As the organic ion exchanger and the inorganic ion exchanger, any one may be used as long as it has an ion exchange capability for replacing the cation of the basic compound with hydrogen. For example, an ion exchange resin or an inorganic ion Exchangers can be used. More specifically, examples of the ion exchange resin include those having an ion exchange group such as a carboxyl group, a sulfonic acid group, and a phosphone group on a resin substrate such as styrene, acrylic, phenol, aliphatic, and pyridine, inorganic Examples of ion exchangers include inorganic layered clay minerals and zeolites.

  As one embodiment of the ion exchange means, for example, ion exchange is performed until the pH of the system is less than about 4 or until substantially all the basic compounds present in the system are removed. Under such conditions, almost the entire amount of the anionic group-containing resin in the system can be precipitated on the pigment surface, compared with the acid precipitation method, and the pigment coated with the resin settles or forms a paste. Become. An anionic group-containing resin-coated pigment can be obtained by filtering, washing with water, and drying if necessary. This anionic group-containing resin-coated pigment can be used in the form of a water-containing cake or in a dried state.

  As another embodiment of the ion exchange means, for example, there is a method of removing a part of the amount of the basic compound present in the system in such a range that the anionic group-containing resin-coated pigment does not settle. The range in which the anionic group-containing resin-coated pigment does not settle varies depending on the degree of hydrophobicity, the degree of hydrophilicity, the weight average molecular weight, the type of aqueous medium used, etc., but preferably the pH of the dispersion liquid Ion exchange until about 4-8. Under such conditions, a part of the anionic group of the anionic group-containing resin deposited on the pigment surface is neutralized and ionized with a basic compound, so that the produced anionic group-containing resin-coated pigment is dispersed. The property is excellent. According to this production method, a dispersion of an anionic group-containing resin-coated pigment having excellent direct pigment dispersibility can be obtained without going through the following redispersion step.

<Dispersion liquid of anionic group-containing resin-coated pigment>
The anionic group-containing resin-coated pigment in the state of the water-containing cake or dried is dissolved in an aqueous medium in the presence of a basic compound and then redispersed to obtain a dispersion of the anionic group-containing resin-coated pigment. It can be used for producing the aqueous inkjet ink composition of the present invention.

  The basic compound and aqueous medium used in the dispersion of the anionic group-containing resin-coated pigment correspond to the basic compound and the aqueous medium described in the method for coating a pigment with the anionic group-containing resin. Can be used.

  The amount of the basic compound used in the redispersion may be an amount that dissolves the anionic group-containing resin-coated pigment in a water-containing cake state or in a dried state, but is usually an anionic group-containing resin. Is used in the range of 80 to 120% of the amount capable of neutralizing.

  The amount of the aqueous medium used in the redispersion is preferably 100 parts by mass or more and 300 parts by mass with respect to 100 parts by mass of the anionic group-containing resin-coated pigment from the viewpoint of reducing the viscosity at the time of redispersion of the resin-coated pigment. Part or more is more preferable. The amount of the aqueous medium used is preferably 1000 parts by mass or less, more preferably 500 parts by mass or less, from the viewpoint of increasing the viscosity at the time of redispersion of the resin-coated pigment with respect to 100 parts by mass of the anionic group-containing resin-coated pigment. In addition, the usage-amount of the aqueous medium in the case of the said re-dispersion shows the total amount with the aqueous medium contained in the said water-containing cake.

<Emulsion>
The emulsion of the present invention is an aqueous emulsion. Examples of water-based emulsions include acrylic resin emulsion, styrene-acrylic resin emulsion, polyester resin emulsion, polyurethane resin emulsion, polyvinyl acetate resin emulsion, polyvinyl chloride resin emulsion, polybutadiene resin emulsion, polyethylene Examples include resin emulsions. Among these, a styrene-acrylic resin emulsion is preferable because the printed matter obtained has excellent appearance and various resistances such as water resistance, solvent resistance, abrasion resistance, and heat resistance. At least one emulsion may be used, and two or more emulsions can be used in combination.

  The glass transition temperature of the resin of the emulsion is −30 ° C. to 30 ° C. The glass transition temperature of the emulsion resin is preferably −25 ° C. or higher, more preferably −20 ° C. or higher, and further preferably −15 ° C. or higher, from the viewpoint of increasing the peeling resistance of printing or increasing the ink ejection stability. The glass transition temperature of the resin of the emulsion is preferably 25 ° C. or less, more preferably 20 ° C. or less, and further preferably 15 ° C. or less from the viewpoint of enhancing the peel resistance of printing.

The glass transition temperature of the resin of the emulsion is a theoretical glass transition temperature obtained by the following wood formula when the resin of the emulsion is an acrylic resin or a styrene-acrylic resin emulsion.
Wood formula: 1 / Tg = W1 / Tg1 + W2 / Tg2 + W3 / Tg3 +... + Wx / Tgx
[Wherein, Tg1 to Tgx are the glass transition temperatures of the respective homopolymers of monomers 1, 2, 3,... X constituting the anionic group-containing resin, and W1 to Wx are monomers 1, 2, 3... Each polymerization fraction of x, Tg represents the theoretical glass transition temperature. However, the glass transition temperature in the wood equation is an absolute temperature. ]
The glass transition temperature of the resin in the emulsion is the theoretical glass transition temperature obtained by thermal analysis for resins other than acrylic resins. As a thermal analysis method, in accordance with JIS K7121 (plastic transition temperature measurement method), as an example, a Pyris1 DSC manufactured by PerkinElmer Co., Ltd. is used, with a temperature rising rate of 20 ° C./min and a nitrogen gas flow rate of 20 ml / min. The glass transition temperature can be measured below.

  The weight average molecular weight of the resin of the emulsion is preferably 10,000 or more, and more preferably 50,000 or more, from the viewpoint of ensuring peel resistance.

  The weight average molecular weight can be measured by a gel permeation chromatography (GPC) method. As an example, Water 2690 (manufactured by Waters) as a GPC apparatus, PLgel 5μ, MIXED-D (manufactured by Polymer Laboratories) as a column, tetrahydrofuran as a developing solvent, column temperature 25 ° C., flow rate 1 ml / min, RI Chromatography is performed under conditions of a detector, a sample injection concentration of 10 milligrams / milliliter, and an injection amount of 100 microliters, and the weight average molecular weight in terms of polystyrene can be obtained.

  The average particle diameter of the emulsion is preferably 500 nm or less, and more preferably 300 nm or less, from the viewpoint of improving the ejection stability of the ink. As an example, the average particle size of the emulsion can be determined by measuring the D50 value using a Nikkiso Microtrac particle size distribution analyzer UPA-150 with a measurement time of 60 seconds and a diluent solvent of water.

<Water-soluble solvent>
The water-soluble solvent of the present invention has the effects of imparting the storage stability, ink ejection stability, and ink flying properties of the water-based inkjet ink composition of the present invention, such as monoalcohols and polyhydric alcohols. And lower alkyl ethers of polyhydric alcohols, nitrogen-containing compounds, and the like. These may be used alone or in combination of two or more.

  Specific examples of the monoalcohol include methanol, ethanol, n-propanol, and n-butanol.

  Specific examples of the polyhydric alcohol include ethylene glycol, propylene glycol, glycerin, diethylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,2-pentanediol, 1,5-pentanediol, neopentyl. Examples include glycol, 1,2-hexanediol, 1,6-hexanediol, 1,2-cyclohexanediol, heptanediol, 1,8-octanediol, and the like.

  Specific examples of the lower alkyl ethers of the polyhydric alcohol include ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol monopropyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether. , Ethylene glycol isobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene Glycol mono -n- butyl ether.

  Examples of the nitrogen-containing compound include pyrrolidone and N-methyl-2-pyrrolidone.

  The water-soluble solvent is preferably at least one selected from the group consisting of propylene glycol, glycerin, diethylene glycol, ethylene glycol monobutyl ether, and diethylene glycol monobutyl ether from the viewpoint of moisture retention.

<Water>
The water of the present invention is used to adjust the concentrations of water as an aqueous medium contained in the dispersion of the anionic group-containing resin-coated pigment, water contained in the emulsion, and the aqueous inkjet ink composition of the present invention. Water to be added.

  The amount of water (total amount of each water) used is 60 parts by mass or more with respect to 100 parts by mass of the water-soluble solvent, from the viewpoint of reducing the viscosity at the time of producing the dispersion of the anionic group-containing resin-coated pigment. Is preferable, and 100 parts by mass or more is more preferable. The amount of the water (total amount of each water) used is 200 parts by mass with respect to 100 parts by mass of the water-soluble solvent from the viewpoint of reducing the storage amount and transport amount of the dispersion of the anionic group-containing resin-coated pigment. The following is preferable, and 150 parts by mass or less is more preferable.

<Other additives>
The water-based inkjet ink composition of the present invention may further include a known pigment dispersant, antifungal agent, rust inhibitor, thickener, antioxidant, ultraviolet absorber, preservability improver, Additives such as foaming agents and pH adjusting agents can also be added.

<Method for Producing Aqueous Inkjet Ink Composition for Pressure-Sensitive Adhesive Layer of Removable Pressure-bonded Recording Paper Having Base Paper and Pressure-Sensitive Adhesive Layer>
The aqueous inkjet ink composition of the present invention can be produced by adding the emulsion, the water-soluble solvent, and the water to the dispersion of the anionic group-containing resin-coated pigment. The aqueous inkjet ink composition of the present invention has an initial viscosity after production of 1 to 15 mPa · s, preferably 3 to 10 mPa · s at 25 ° C. The viscosity can be measured by, for example, an E type viscometer (trade name: RE100L type viscometer, manufactured by Toki Sangyo Co., Ltd.).

  Hereinafter, the ratio of each component in the aqueous inkjet ink composition of the present invention will be described.

  The proportion of the anionic group-containing resin-coated pigment in the aqueous inkjet ink composition of the present invention is preferably 2% by mass or more and more preferably 4% by mass or more from the viewpoint of increasing the print density of the printed matter. The proportion of the anionic group-containing resin-coated pigment in the aqueous inkjet ink composition of the present invention is preferably 10% by mass or less, more preferably 8% by mass or less, from the viewpoint of enhancing the ejection stability of the ink.

  The ratio of the resin solid content of the emulsion in the aqueous inkjet ink composition of the present invention is 0.7 to 7% by mass. The ratio of the resin solid content of the emulsion in the aqueous inkjet ink composition of the present invention is preferably 0.8% by mass or more, more preferably 1.0% by mass or more, from the viewpoint of enhancing the peeling resistance of printing. 2 mass% or more is more preferable. The ratio of the resin solid content of the emulsion in the aqueous inkjet ink composition of the present invention is preferably 6% by mass or less, more preferably 5% by mass or less, and more preferably 4% by mass or less from the viewpoint of improving the ejection stability of the ink. Further preferred. The resin solid content of the emulsion includes a surfactant contained in the emulsion.

  The ratio of the water-soluble solvent in the aqueous inkjet ink composition of the present invention is 25 to 55% by mass. The proportion of the water-soluble solvent in the water-based inkjet ink composition of the present invention is preferably 30% by mass, more preferably 35% by mass or more from the viewpoint of improving the ejection stability of the ink. The proportion of the water-soluble solvent in the aqueous inkjet ink composition of the present invention is preferably 50% by mass or less, and more preferably 45% by mass or less from the viewpoint of increasing the peel resistance of printing. In addition, when the kind of the said aqueous medium corresponds to a water-soluble solvent, let the total amount which added the said aqueous medium contained in the ink composition for water-based inkjets of this invention be content of a water-soluble solvent.

  The ratio of the water (total amount of each water) in the aqueous inkjet ink composition of the present invention is preferably 40% by mass or more, and more preferably 50% by mass or more from the viewpoint of improving the ejection stability of the ink. The ratio of the water (total amount of each water) in the aqueous inkjet ink composition of the present invention is preferably 70% by mass or less, and more preferably 60% by mass or less from the viewpoint of enhancing the ejection stability of the ink.

  Furthermore, the ratio of the pigment and the anionic group-containing resin contained in the anionic group-containing resin-coated pigment, and the ratio of the basic compound during the redispersion will be described.

  The proportion of the pigment in the aqueous inkjet ink composition of the present invention is preferably 1% by mass or more, and more preferably 2% by mass or more from the viewpoint of increasing the print density of the printed matter. The proportion of the pigment in the aqueous inkjet ink composition of the present invention is preferably 10% by mass or less, and more preferably 5% by mass or less from the viewpoint of improving the ejection stability of the ink.

  The proportion of the anionic group-containing resin in the aqueous inkjet ink composition of the present invention is preferably 0.5% by mass or more from the viewpoint of enhancing the dispersion stability of the dispersion of the anionic group-containing resin-coated pigment. The mass% or more is more preferable. The proportion of the anionic group-containing resin in the aqueous inkjet ink composition of the present invention is preferably 4% by mass or less, more preferably 2% by mass or less from the viewpoint of reducing the viscosity of the aqueous inkjet composition of the present invention. .

  From the viewpoint of improving the dispersion stability of the ink, the proportion of the basic compound in the re-dispersion in the aqueous inkjet ink composition of the present invention is preferably 0.05% by mass or more, and 0.1% by mass or more. More preferred. The proportion of the basic compound in the redispersion in the aqueous inkjet ink composition of the present invention is preferably 1% by mass or less and more preferably 0.5% by mass or less from the viewpoint of increasing the water resistance of the printed matter.

<Printing method>
The printing method using the aqueous inkjet ink composition of the present invention will be described.

  Examples of the printing medium of the water-based inkjet ink composition of the present invention include a pre-glue type releasable pressure-sensitive recording paper having a pressure-sensitive adhesive layer on a base paper. Specific examples of the pre-adhesive re-peelable pressure-sensitive recording paper include POSTEX (made by Toppan Forms), W-mail (made by Hokuetsu Kishu Paper Co., Ltd.), Rica Mail (made by Nippon Science Paper Co., Ltd.), etc. Paste-type re-peelable pressure-sensitive recording paper base paper includes art paper, coated paper such as inkjet exclusive paper, inkjet glossy paper, plastic base materials such as polyvinyl chloride sheets, plain paper and offset paper Uncoated paper such as can also be used.

  As a printing method of the aqueous inkjet ink composition of the present invention, for example, the aqueous inkjet ink composition of the present invention is accommodated in an ink cartridge, and the ink cartridge is mounted on a single-pass inkjet recording apparatus, There is a method of performing ink jet printing by spraying from a nozzle onto a pre-glue type releasable pressure-sensitive recording paper.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples. Note that “%” means “mass%” unless otherwise specified.

Compounds used in the following examples or comparative examples of the present application are shown.
<Pigment>
Carbon black (trade name Printex 90, manufactured by Degussa)
Yellow pigment (trade name Nova Palm Yellow 4G01, manufactured by Clariant)
Magenta pigment (trade name inkjet magenta E5B02, manufactured by Clariant)
Cyan pigment (trade name Heliogen Blue L7101F, manufactured by BASF)
<Anionic group-containing resin>
Acrylic acid / n-butyl acrylate / benzyl methacrylate / styrene copolymer (weight average molecular weight 30,000, acid value 185 mgKOH / g)
<Emulsion>
Neoacryl A-1092 (45% solids, glass transition temperature 9 ° C., styrene-acrylic emulsion, manufactured by DSM Neoresins)
Neoacryl A-1120 (solid content 45%, glass transition temperature -9 ° C., styrene-acrylic emulsion, manufactured by DSM Neoresins)
Neoacryl A-1091 (solid content 45%, glass transition temperature 98 ° C., styrene-acrylic emulsion, manufactured by DSM Neoresins)
Mobile 461 (solid content 64%, glass transition temperature -40 ° C., acrylic emulsion, manufactured by Nippon Synthetic Chemical)
<Water-soluble solvent>
Glycerin Propylene glycol Ethylene glycol monobutyl ether

<Example 1>
<Manufacture of anionic group-containing resin-coated pigment>
20 parts by weight of anionic group-containing resin (acrylic acid / n-butyl acrylate / benzyl methacrylate / styrene copolymer), 2.5 parts by weight of basic compound (potassium hydroxide) and 77.5 parts by weight of aqueous medium (water) The resin dispersant varnish having an anionic group-containing resin solid content of 20% was obtained.
Next, 64.3 parts by mass of an aqueous medium (water) is added to 23.7 parts by mass (including 4.74 parts by mass of an anionic group-containing resin) of the resin dispersant varnish, and mixed to obtain an anionic group-containing resin solid content. Was 4.74% of a pigment-dispersing resin varnish. Further, 12 parts by mass of pigment (carbon black) was added thereto, and after stirring and mixing, the mixture was kneaded with a wet circulation mill to prepare an anionic group-containing resin-coated pigment dispersion (ink base precursor).
Further, the anionic group-containing resin-coated pigment dispersion (ink base precursor) is diluted with water so that the pigment concentration becomes 5%, and then the cation exchange resin (DOWEX MONOSSPHERE (H)) is added to the diluted solution. 650C, manufactured by Dow Chemical Co., Ltd.) was added and stirred. After ion exchange until the pH was less than 4, the ion exchange resin was filtered through a mesh, suction filtered, and an anionic group-containing resin-coated pigment (black) ) -Containing cake (anionic group-containing resin-coated pigment solid content 25%).

<Production of dispersion of anionic group-containing resin-coated pigment>
22.8 parts by weight of a water-containing cake containing this anionic group-containing resin-coated pigment (including 1.6 parts by weight of anionic group-containing resin, 4.1 parts by weight of pigment, and 17.1 parts by weight of an aqueous medium (water)) 0.2 parts by weight of a basic compound (sodium hydroxide) (a neutralization amount of 80% of the acid value of the anionic group-containing resin contained in the resin-coated pigment) and 11 parts by weight of an aqueous medium (water) In addition, the mixture was stirred with a high-pressure emulsifying and dispersing apparatus: Gorin homogenizer (manufactured by APGAULIN INK.) To obtain a dispersion of an anionic group-containing resin-coated pigment (black).

<Production of water-based inkjet ink composition for pressure-sensitive adhesive layer of releasable pressure-sensitive adhesive recording paper having base paper and pressure-sensitive adhesive>
As described in Table 1, 34.0 parts by mass of the dispersion of the anionic group-containing resin-coated pigment (black), 3.3 parts by mass of the emulsion (neoacryl A-1092), and 40.0 masses of the water-soluble solvent (glycerin). Part and 22.7 parts by mass of water were mixed with stirring to obtain an aqueous inkjet ink composition for the pressure-sensitive adhesive layer of the releasable pressure-sensitive recording paper of Example 1.

<Examples 2-9, Comparative Examples 1-6>
Except having changed into the pigment of Table 1, the anionic group containing resin-coated pigment of Examples 2-9 and Comparative Examples 1-6 was obtained by the method of Example 1. Further, a predetermined emulsion, a predetermined water-soluble solvent, and water were stirred and mixed so that the mass ratios shown in Table 1 were obtained, and the releasable pressure-sensitive recording papers of Examples 2 to 9 and Comparative Examples 1 to 6 were sensed. An aqueous inkjet ink composition for a pressure-sensitive adhesive layer was obtained.

<Printing Evaluation of Aqueous Inkjet Ink Composition for Pressure Sensitive Adhesive Layer of Removable Pressure-Sensitive Recording Paper Having Base Paper and Pressure Sensitive Adhesive>
Evaluation was made by the following method, and the results are shown in Table 1.
(1) Print peeling resistance The aqueous ink-jet ink compositions of Examples 1 to 9 and Comparative Examples 1 to 6 were developed in W mail (manufactured by Hokuetsu Kishu Paper Co., Ltd.) using a 0.1 mm wire bar. After 30 minutes, the color-extended surface and the non-color-extended surface were overlapped and pressure bonded at a pressure of 15 MPa to obtain a removable information sheet. Thereafter, the pressure bonding surface is peeled off, ΔE of the non-color-developing surface after pressure bonding and ΔE of the non-pressure-developing non-color-developing surface are measured, and the difference between them is calculated, so that the color development surface changes to the non-color-developing surface. The degree of color transfer was evaluated. Measurement equipment and measurement conditions are as follows.
[measuring equipment]
SpectroEye (manufactured by X-rite)
[Measurement condition]
White standard: Absolute white light source: D50
Observation field: 2 °
Built-in filter: None [Evaluation criteria]
○: ΔE is 0.5 or less
Δ: ΔE is more than 0.5 and less than 1 ×: ΔE is more than 1

(2) Ink ejection stability Using a commercially available inkjet printer PM-900C (manufactured by Seiko Epson Corporation), the aqueous inkjet ink compositions of Examples 1 to 9 and Comparative Examples 1 to 6 are printed on plain paper. The ejection stability was evaluated. Ejection stability is achieved by filling the water-based inkjet ink composition, leaving it for 3 days in an environment with a room temperature of 30 ° C. and a relative humidity of 50% without a cap, and ejecting from the orifice depending on the conditions that allow printing. Stability was evaluated. Inkjet printers and plain paper used the following.
Inkjet printer: PM-900C (manufactured by Seiko Epson Corporation)
Plain paper: Xerox L (Fuji Xerox Office Supply Co., Ltd.)
[Evaluation criteria]
○: Printing is possible without cleaning the discharge orifice. Δ: The discharge orifice needs to be cleaned one to four times before printing is possible. ×: The discharge orifice needs to be cleaned five times or more before printing is possible.

  According to the results of Examples 1 to 9, the water-based inkjet ink composition for the pressure-sensitive adhesive layer of the releasable pressure-sensitive recording paper having the base paper of the present invention and the pressure-sensitive adhesive has the following characteristics. Since the discharge stability of the ink is good, it has a good effect of preventing transfer of printing and a good coating stability, and it is understood that these properties are stable regardless of the type of pigment.

As a result of Comparative Example 1, when an emulsion having a glass transition point of 98 ° C. was used, the peeling resistance of printing was insufficient. As a result of Comparative Example 2, when an emulsion having a glass transition point of −40 ° C. was used, the peeling resistance of printing and the ejection stability of ink were insufficient. As a result of Comparative Example 3, when an emulsion having a glass transition point of 9 ° C. was used excessively, the ink ejection stability was insufficient. As a result of Comparative Example 4, when the amount of the emulsion having a glass transition point of 9 ° C. was insufficient, the peeling resistance of printing was insufficient. As a result of Comparative Example 5, when an excessive amount of water-soluble solvent was used, both the peeling resistance of printing and the ejection stability of ink were insufficient. As a result of Comparative Example 6, when the amount of the water-soluble solvent used was insufficient, the ink ejection stability was insufficient.

Claims (4)

An aqueous inkjet ink composition containing an anionic group-containing resin-coated pigment, an emulsion, a water-soluble solvent, and water,
The glass transition temperature of the resin of the emulsion is -30 ° C to 30 ° C,
Base paper and pressure-sensitive adhesive, wherein the resin solid content of the emulsion in the water-based inkjet ink composition is 0.7 to 7% by mass, and the water-soluble solvent is 25 to 55% by mass. An aqueous inkjet ink composition for a pressure-sensitive adhesive layer of a releasable pressure-sensitive recording paper having a layer.   The pressure sensitive adhesive layer of a releasable pressure-sensitive adhesive recording sheet having a base paper and a pressure sensitive adhesive layer according to claim 1, wherein the emulsion is an acrylic resin emulsion and / or a styrene-acrylic resin emulsion. Water-based inkjet ink composition.   The base paper and pressure-sensitive adhesive layer according to claim 1 or 2, wherein the water-soluble solvent is at least one selected from the group consisting of propylene glycol, glycerin, diethylene glycol, ethylene glycol monobutyl ether, and diethylene glycol monobutyl ether. A water-based ink jet ink composition for a pressure-sensitive adhesive layer of a releasable pressure-sensitive recording paper having the following. Removable pressure-bonding obtained by printing the water-based inkjet ink composition according to any one of claims 1 to 3 on a pressure-sensitive adhesive layer of a releasable pressure-sensitive recording sheet having a base paper and a pressure-sensitive adhesive layer. Recorded paper printed matter.