JP2023064341A - Adhesive label for inkjet recording - Google Patents

Abstract

To provide an adhesive label for inkjet recording which allows a recording surface and an adhesive layer that are brought into contact with each other in a state of being wound in rolled states to be easily peeled without using peeling paper, and is excellent in uniformity of a printed image.SOLUTION: An adhesive label for inkjet printing has an ink receiving layer and a release layer containing a silicone resin having elongation at break of 200% or more on the ink receiving layer, on one surface of a support, and has an adhesive layer on the other surface of the support.SELECTED DRAWING: None

Description

The present invention relates to an inkjet recording pressure-sensitive adhesive label that can be easily peeled off from the recording surface in contact with the pressure-sensitive adhesive layer in a rolled state without using a release paper, and that has excellent uniformity of printed images. is.

Adhesive labels for ink jet recording are rapidly becoming popular in recent years because they can be easily printed in full color and at high speed, and can be printed in small lots. Generally, the adhesive label is constructed by providing an adhesive layer on a backside support having no ink-receiving layer, and a release paper on the adhesive layer. The release paper becomes unnecessary after the label is attached to the adherend, but it is difficult to dispose of because it cannot be converted into recycled pulp by ordinary used paper recovery equipment. In addition, since the thickness of the product increases by the thickness of the release paper, the diameter of the roll per unit length increases when the product is wound into a roll shape.

In order to solve the problems caused by having the release liner, it is common practice to eliminate the need for the release liner by providing a release layer on the surface of the recording layer. However, in the case of an inkjet recording pressure-sensitive adhesive label having an ink-receiving layer with particularly excellent ink absorption, the ink-receiving layer on the recording surface is bulky and porous, so the release agent is directly applied to the surface of the ink-receiving layer. If this is done, the release agent will be absorbed into the ink-receiving layer, making it impossible to obtain sufficient release performance. In addition, if a large amount of release agent is applied to enhance release performance, voids in the ink-receiving layer will be filled, impairing ink absorbency, and the surface will become highly hydrophobic, causing ink to land on the surface. Since the spread of the image is hindered, problems such as deterioration of image quality occur.

In order to solve the above-mentioned problems, as a release agent contained in the release layer, an inkjet using a compound selected from long-chain alkyl group-containing polyvinyl alcohol, long-chain alkyl group-containing aminoalkyd resin, and long-chain alkyl group-containing polyethyleneimine A recording adhesive label has been proposed (Patent Document 1). However, in the case of a gloss type ink-receiving layer with a small pore diameter, the decrease in ink absorption is still a problem. On the other hand, an inkjet recording adhesive label using a mixture of a styrene polymer and a silicone release agent or a mixture of a styrene polymer and a perfluoro release agent as a release agent has been proposed (Patent Reference 2). However, the adhesive label is intended for output with non-aqueous ink and cannot be image-formed with general aqueous ink.

On the other hand, an ink-jet recording pressure-sensitive adhesive label intended for output with water-based ink has been proposed, in which the surface of the ink-receiving layer is coated with a release layer containing a silicone resin so that the coverage is 20 to 70% ( Patent document 3). However, it is difficult to uniformly cover the surface of the release layer with the above coverage, and uneven ink absorption and deterioration of image quality occur in areas where the release layer becomes a local continuous layer. In some cases, image uniformity such as graininess and gloss unevenness is problematic. Further, an ink-jet recording pressure-sensitive adhesive label has been proposed in which peeling portions thicker than the thickness of the pressure-sensitive adhesive layer are discretely provided on the surface of the ink-receiving layer (Patent Document 4). However, even though they are provided discretely, the peeling portions have poor ink absorption ability, and thus, when printing high-quality images, the uniformity of the image may be similarly inferior in some cases.

Japanese Patent Application Laid-Open No. 2001-139900 JP-A-2005-29718 JP 2014-195994 A JP 2019-199504 A

The present invention provides an ink-jet recording pressure-sensitive adhesive label in which the recording surface and the pressure-sensitive adhesive layer in contact with each other in a rolled state can be easily peeled off without using a release paper, and the printed image is excellent in uniformity. The task is to

As a result of intensive studies in order to solve the above problems, the inventors of the present invention have found that the above problems can be solved by an inkjet recording pressure-sensitive adhesive label having the following configuration.

An ink-receiving layer is provided on one side of the support, and a release layer containing a silicone resin having an elongation at break of 200% or more is provided on the ink-receiving layer. An adhesive label for inkjet recording having an agent layer.

ADVANTAGE OF THE INVENTION According to the present invention, there is provided an ink-jet recording pressure-sensitive adhesive label that can be easily peeled off from the pressure-sensitive adhesive layer in contact with the recording surface in a rolled state without using a release paper, and that has excellent uniformity of printed images. can do.

The inkjet recording pressure-sensitive adhesive label of the present invention will be described in detail below.

The ink-receiving layer of the adhesive label for inkjet recording of the present invention preferably contains mainly inorganic fine particles having an average secondary particle size of 500 nm or less from the viewpoint of obtaining good color developability. Here, "mainly containing" means that the inorganic fine particles are contained in an amount of 50% by mass or more, preferably 60 to 96% by mass, based on the total solid content of the ink-receiving layer. The inorganic fine particles contained in the ink-receiving layer are preferably hydrophilic inorganic fine particles, and examples thereof include various known inorganic fine particles such as amorphous synthetic silica, alumina, alumina hydrate, calcium carbonate, magnesium carbonate, and titanium dioxide. However, amorphous synthetic silica, alumina or alumina hydrate is preferred in that high print density and excellent image sharpness can be obtained.

Amorphous synthetic silica can be broadly classified into wet process silica, gas phase process silica, and others according to the manufacturing method. Wet-process silica is further classified into precipitation-process silica, gel-process silica, and sol-process silica according to the production method. Precipitation silica is produced by reacting sodium silicate and sulfuric acid under alkaline conditions, and the grown silica particles are aggregated and precipitated, then filtered, washed with water, dried, pulverized, and classified to produce products. Precipitated silica is commercially available, for example, from Tosoh Silica Corporation as NipSeal (registered trademark). Gel silica is produced by reacting sodium silicate and sulfuric acid under acidic conditions. During aging, the fine particles dissolve and re-precipitate to bind other primary particles together, so that well-defined primary particles disappear and form relatively hard agglomerated particles with an internal void structure. Gel method silica is commercially available from Tosoh Silica Corporation as Nipgel (registered trademark), for example. Sol-method silica, also called colloidal silica, is obtained by heating and aging a silica sol obtained by metathesis of sodium silicate with an acid or the like or through an ion-exchange resin layer. It is commercially available.

Vapor-phase silica is also called a dry method as opposed to a wet method, and is generally produced by a flame hydrolysis method. Specifically, a method of burning silicon tetrachloride with hydrogen and oxygen is generally known, but instead of silicon tetrachloride, silanes such as methyltrichlorosilane and trichlorosilane can also be used alone or with silicon tetrachloride. It can be used in a mixed state with Vapor-phase silica is commercially available from Nippon Aerosil Co., Ltd. as AEROSIL (registered trademark) and from Tokuyama Corporation as Leorosil (registered trademark).

Vapor-phase silica is preferably used in the ink-receiving layer of the inkjet recording material of the present invention. The average primary particle size of the fumed silica contained in the ink-receiving layer is preferably 30 nm or less from the viewpoint of color development, and the average primary particle size is 3 to 15 nm and the specific surface area measured by the BET method is 200 m ² /g or more. is more preferable, and those having an average primary particle size of 3 to 10 nm and a specific surface area of 250 to 500 m ² /g as determined by the BET method are particularly preferable. The average primary particle size as used in the present invention is the diameter of a circle equal to the projected area of each of 100 primary particles existing within a certain area obtained by electron microscopic observation of fine particles, and the average value of the particle sizes is obtained. is. The BET method as used in the present invention is one of methods for measuring the surface area of powder by the vapor phase adsorption method, and is a method for determining the total surface area of 1 g of a sample, that is, the specific surface area, from the adsorption isotherm. Nitrogen gas is generally used as the adsorbed gas, and the method of measuring the amount of adsorption from changes in the pressure or volume of the gas to be adsorbed is most often used. The Brunauer-Emmett-Teller equation, which is called the BET equation and is widely used to determine the surface area, is the most famous for expressing the isotherm of multimolecular adsorption. The amount of adsorption is determined based on the BET formula and multiplied by the area occupied by one adsorbed molecule on the surface to obtain the surface area.

The gas phase method silica can preferably be used when dispersed in the presence of a cationic compound. As described above, the fumed silica used in the present invention is preferably dispersed to have an average secondary particle size of 500 nm or less, more preferably 10 to 300 nm, from the viewpoint of color development. Gas-phase silica can be dispersed by pre-mixing gas-phase silica and a dispersion medium by conventional propeller stirring, turbine-type stirring, homomixer-type stirring, etc., followed by media mills such as ball mills, bead mills, and sand grinders. Dispersion is preferably carried out using a pressure-type disperser such as a high-pressure homogenizer or an ultra-high-pressure homogenizer, an ultrasonic disperser, a thin-film orbital disperser, or the like. The average secondary particle size referred to in the present invention refers to the number median size measured using a laser scattering particle size distribution analyzer (for example, LA920 manufactured by Horiba, Ltd.).

In the present invention, wet process silica can also be preferably used. As the wet-process silica contained in the ink-receiving layer, precipitation-process silica or gel-process silica is preferable, and precipitation-process silica is particularly preferable, from the viewpoint of color development. The wet-process silica used in the present invention preferably has an average secondary particle size of 500 nm or less, more preferably 20 to 300 nm, from the viewpoint of color development. The average primary particle size of the wet-process silica used in the present invention is preferably 50 nm or less, more preferably 3 to 40 nm.

Wet-process silica can preferably be used after being dispersed and pulverized in the presence of a cationic compound. As a pulverization method, a wet dispersion method in which silica dispersed in an aqueous medium is mechanically pulverized can be preferably used. A preferred method for pulverizing the wet-process silica used in the present invention will be described. First, silica particles and a cationic compound are mixed in a dispersion medium mainly composed of water, and at least one dispersing device such as a sawtooth blade dispersing machine, a propeller vane dispersing machine, or a rotor-stator dispersing machine is used. to obtain a silica predispersion. If necessary, an appropriate low boiling point solvent or the like may be added to the aqueous dispersion medium. The solid content concentration of the silica pre-dispersion liquid is preferably high, but if the concentration becomes too high, dispersion becomes impossible. The silica pre-dispersion is then preferably subjected to mechanical means with higher shear forces to comminute the silica particles. As the mechanical means, known methods can be employed, for example, media mills such as ball mills, bead mills, and sand grinders, pressure-type dispersers such as high-pressure homogenizers and ultra-high-pressure homogenizers, ultrasonic dispersers, thin-film swirling dispersers, and the like. can be used.

A cationic polymer can be preferably used as the cationic compound used for dispersing or pulverizing the vapor-phase silica and the wet-process silica. Examples of cationic polymers include polyethyleneimine, polydiallylamine, polyallylamine, alkylamine polymers, JP-A-59-20696, JP-A-59-33176, JP-A-59-33177, JP-A-59-33177 and JP-A-59-33177. 59-155088, JP-A-60-11389, JP-A-60-49990, JP-A-60-83882, JP-A-60-109894, JP-A-62-198493 , JP-A-63-49478, JP-A-63-115780, JP-A-63-280681, JP-A-1-40371, JP-A-6-234268, JP-A-7-125411 Polymers having primary to tertiary amino groups and quaternary ammonium bases described in JP-A-10-193776 and the like are preferably used. In particular, a diallylamine derivative is preferably used as the cationic polymer. From the viewpoint of dispersibility and dispersion viscosity stability, the mass average molecular weight of these cationic polymers is preferably about 2,000 to 100,000, more preferably about 2,000 to 30,000.

As the alumina contained in the ink-receiving layer, γ-alumina, which is a γ-type crystal of aluminum oxide, is preferable, and δ-group crystal is particularly preferable. γ-alumina can be made to have primary particles as small as about 10 nm, but it is usually produced by pulverizing secondary particle crystals of several thousand to tens of thousands of nanometers using ultrasonic waves, high-pressure homogenizers, counter-collision jet pulverizers, etc. can be used. In the present invention, from the viewpoint of color development, it is preferable to use alumina having an average secondary particle size of 500 nm or less, more preferably in the range of 20 to 300 nm.

Alumina hydrate contained in the ink-receiving layer is represented by a constitutive formula of Al ₂ O ₃ ·nH ₂ O (n=1 to 3). Alumina hydrate used in the present invention can be obtained by known production methods such as hydrolysis of aluminum alkoxide such as aluminum isopropoxide, neutralization of aluminum salt with alkali, hydrolysis of aluminate, and the like. The alumina hydrate used in the present invention also preferably has an average secondary particle size of 500 nm or less, more preferably 20 to 300 nm, from the viewpoint of color development.

The alumina and alumina hydrate used in the present invention are preferably dispersed with a known dispersant such as acetic acid, lactic acid, formic acid and nitric acid.

Two or more kinds of inorganic fine particles selected from the inorganic fine particles described above can be used in combination. Examples include combined use of finely pulverized wet-process silica and vapor-phase silica, combined use of finely-pulverized wet-process silica and alumina or alumina hydrate, and combined use of vapor-phase silica and alumina or alumina hydrate. be done.

The ink-receiving layer of the adhesive label for inkjet recording of the invention preferably contains a water-soluble binder. As the water-soluble binder, polyvinyl alcohol, polyethylene glycol, starch, dextrin, carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid ester, and derivatives thereof are used, and among them, completely saponified or partially saponified polyvinyl alcohol is preferred. In particular, those having a degree of saponification of 80% or more are particularly preferred. The average degree of polymerization of polyvinyl alcohol is preferably 500-6000, more preferably 1000-5000.

The polyvinyl alcohol includes, in addition to general polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and other polyvinyl alcohol derivatives. One type of polyvinyl alcohol may be used alone, or two or more types may be used in combination.

The content of the water-soluble binder in the ink-receiving layer is preferably as small as possible in view of increasing the void volume in the ink-receiving layer and increasing the ink absorbability. 3 to 40% by mass, more preferably 5 to 30% by mass, based on the total amount of the inorganic fine particles. As a result, the ink-receiving layer can be a porous ink-receiving layer with excellent ink absorption.

The ink-receiving layer preferably contains a cross-linking agent in addition to the water-soluble binder described above. By containing a cross-linking agent, the occurrence of surface defects such as cracks can be suppressed, and the ink absorbability is also improved. As the cross-linking agent, those known as cross-linking agents for water-soluble binders can be used. When polyvinyl alcohol is used as the water-soluble binder, boric acid or boric acid salts are particularly preferred. Moreover, when polyvinyl alcohol contains a highly active modifying group, a known cross-linking agent may be used according to the modifying group. The amount of the cross-linking agent added is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass, based on the water-soluble binder.

In the present invention, the ink-receiving layer may further contain, as an additive, a cationic polymer similar to that used for cationizing the amorphous synthetic silica described above. The ink-receiving layer may also contain a water-soluble polyvalent metal compound for improving water resistance. A water-soluble aluminum compound can be preferably used as the water-soluble polyvalent metal compound.

Water-soluble aluminum compounds include, for example, inorganic salts such as aluminum chloride or its hydrate, aluminum sulfate or its hydrate, ammonium alum, and the like. Furthermore, basic polyaluminum hydroxide compounds, which are inorganic cationic aluminum-containing polymers, are known.

Among these water-soluble aluminum compounds, those that can be stably added to the coating solution forming the ink-receiving layer are preferred, and basic polyaluminum hydroxide compounds are preferably used. The main component of this compound is represented by the following formulas 1, 2 or 3. For example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ⁵⁺ It is a water-soluble polyaluminum hydroxide stably containing basic, high-molecular polynuclear condensation ions such as [Al ₂₁ (OH) ₆₀ ] ³⁺ .

[Al ₂ (OH) _n Cl _6-n ] _m Formula 1
[Al(OH) ₃ ] _n AlCl ₃ Formula 2
Al _n (OH) _m Cl _(3n-m) 0<m<3n Formula 3

These products are available from Taki Chemical Co., Ltd. under the name of polyaluminum chloride (PAC) as a water treatment agent, from Asada Chemical Industry Co., Ltd. under the name of polyaluminum hydroxide (Paho), and from Riken Co., Ltd. It is marketed by Green under the name Purachem WT and by other manufacturers for similar purposes, and is readily available in various grades.

The content of the water-soluble polyvalent metal compound described above is preferably in the range of 0.1 to 10% by mass relative to the inorganic fine particles contained in the ink receiving layer.

The ink-receiving layer further contains a coloring dye, a coloring pigment, an ultraviolet absorber, an antioxidant, a pigment dispersant, an antifoaming agent, a surfactant, a leveling agent, a preservative, a fluorescent whitening agent, a viscosity stabilizer, and a pH adjuster. Various known additives such as additives can also be added.

In addition, the storability after printing can be improved by incorporating a thioether compound, a carbohydrazide, and a derivative thereof into the ink-receiving layer.

The carbohydrazide derivative used in the present invention may be a compound having one or more carbohydrazide structures in the same molecule, or a polymer having a carbohydrazide structure in the main chain or side chain of the molecule. .

Thioether compounds used in the present invention include aromatic thioether compounds in which aromatic groups are bonded to both sides of a sulfur atom, and aliphatic thioether compounds having alkyl groups at both ends of a sulfur atom. Among these, an aliphatic thioether compound having a hydrophilic group is particularly preferred.

In the present invention, the coating weight of the ink-receiving layer after drying is preferably 10 to 60 g/ ^m2 . Preferably the amount is between 20 and 60 g/m ² .

Coating methods for the ink-receiving layer include the slide curtain method, slide bead method, slot die method, direct gravure roll method, reverse gravure roll method, spray method, air knife method, blade coating method, rod bar coating method, and spin coating method. are exemplified.

Next, the release layer will be described. In the present invention, the release layer contains a silicone resin having an elongation at break of 200% or more. The elongation at break is defined in JIS K 6251:2017 and indicates the elongation when the test piece is cut. In the present invention, by containing a silicone resin having an elongation at break of 200% or more in the release layer, it is possible to form a release layer with excellent uniformity of printed images. Silicone resin-forming liquids include a one-liquid type that cures alone, a two-liquid type that contains a curing agent, and an aqueous emulsion type. It is preferable to use the water-based emulsion type in that it has little adverse effect on ink absorbency.

The silicone resin-forming aqueous emulsion is a one-liquid type consisting of a combination of a main agent (base polymer), a cross-linking agent, and, if necessary, a catalyst such as a tin compound. The main agent (base polymer) is an organopolysiloxane having at least two silicon-bonded curing reactive groups per molecule, and is emulsified and dispersed in water. Examples of the curing reactive group include hydrolyzable groups such as hydroxyl groups and alkoxy groups, with alkoxy groups being preferred. Examples of cross-linking agents include ethyl silicate, propyl silicate, methyltrimethoxysilane, and methyltriethoxysilane. The main agent (base polymer), the cross-linking agent, and the catalyst added as necessary advance the condensation reaction to form a silicone resin.

Examples of the aqueous emulsion for forming a silicone resin include POLON-MF-56, KM-9749, KM-2002-T, KM-2002-L-1 and KM-9772 from Shin-Etsu Chemical Co., Ltd. It is commercially available from Toray Industries, Inc. as IE-7170.

The coating amount of the release layer after drying is preferably 0.01 to 0.2 g/m ² , more preferably 0.03 to 0.1 g/m ² , and 0.04 to 0.09 g/m ^{2 .} is particularly preferred. If it exceeds 0.2 g/m ² , the ink absorption may deteriorate.

In addition to the aqueous emulsion for forming a silicone resin, the release layer can further contain various known additives described in the section of the ink-receiving layer.

The coating method of the release layer includes slide curtain method, slide bead method, slot die method, direct gravure roll method, reverse gravure roll method, spray method, air knife method, blade coating method, rod bar coating method, spin coat method, Various coating methods such as an inkjet method are exemplified. Among them, the reverse gravure roll method is preferable, and from the viewpoint of coating uniformity, a reverse gravure roll method using a diagonal gravure roll (gravure roll having diagonal grooves) with a roll diameter of 100 mm or less (more preferably 20 to 80 mm). is preferred.

The support of the adhesive label for inkjet recording of the present invention includes films such as polyethylene, polypropylene, polyvinyl chloride, diacetate resin, triacetate resin, cellophane, acrylic resin, polyethylene terephthalate, and polyethylene naphthalate, polypropylene resin and inorganic filler. are blended to form a synthetic paper manufactured by a biaxially oriented film forming method (e.g., Yupo (registered trademark), manufactured by Yupo Corporation), non-absorbent supports such as polyolefin resin-coated paper, fine paper, Absorbent supports such as art paper and coated paper are exemplified. Among them, a non-absorbent support is preferable in that high glossiness can be obtained, but on the other hand, it does not absorb the solvent component in the ink. A porous ink-receiving layer having excellent ink absorbability is preferably provided on such a non-absorbent support, and the present invention is particularly useful for ink jet recording materials having such a structure. These supports having a thickness of about 50 to 300 μm are preferably used.

When a film or polyolefin resin-coated paper, which is a non-absorbent support, is used, the surface on which the ink-receiving layer is to be provided can be subjected to activation treatment such as corona discharge treatment or flame treatment.

When a film or polyolefin resin-coated paper is used as the support, the support may be provided with a known undercoat layer containing gelatin, various urethane resins, polyvinyl alcohol, etc. on the surface on which the ink-receiving layer is to be provided, or may It is preferable to use an easy-adhesion treated article provided with a layer for improving the adhesion (for example, a polyethylene terephthalate film subjected to an easy-adhesion treatment). It is also preferable to improve the wettability of the non-absorbent support by corona treatment or plasma treatment.

The coating amount of the undercoat layer is not particularly limited, but the coating amount after drying is preferably in the range of 0.005 to 2.0 g/m ² , more preferably in the range of 0.01 to 1.0 g/m ² . , 0.02 to 0.5 g/m ² is particularly preferred.

The pressure-sensitive adhesive layer of the present invention is provided on the other side of the support than the side on which the ink-receiving layer is provided. Various adhesives, such as a solvent type adhesive and an emulsion type adhesive, can be used for the adhesive used for an adhesive layer. The coating amount of the adhesive layer after drying is preferably 1 to 30 g/m ² , more preferably 2 to 20 g/m ² . If the coating amount after drying is less than 1 g/m ² , sufficient adhesive strength may not be obtained when used as a label, while if it exceeds 30 g/m ² , the adhesive strength may saturate.

Meyer bar coater, kiss roll coater, lip coater, direct roll coater, offset roll coater, gravure roll coater, reverse roll coater, rod coater, blade coater, comma direct coater, comma reverse coater, Air knife coaters, slit die coaters and the like are suitable. Further, the pressure-sensitive adhesive is not applied to the surface of the support opposite to the surface on which the ink-receiving layer is to be provided, but is once applied to the process paper, and after drying, the pressure-sensitive adhesive is applied to the surface of the support opposite to the surface to which the ink-receiving layer is to be provided. It is also possible to apply the pressure-sensitive adhesive layer by a method of transferring to the surface and then peeling off the process paper.

EXAMPLES The present invention will be described in detail below with reference to examples, but the content of the present invention is not limited to the examples. In addition, "parts" and "%" in the examples and comparative examples indicate mass parts and mass% of solid content or substantial components unless otherwise specified.

(Example 1)
As a support, a polyethylene terephthalate film having a thickness of 100 μm (manufactured by Mitsubishi Chemical Corporation, total light transmittance of 89%) subjected to an easy-adhesion treatment was coated with 25 g of the ink-receiving layer coating liquid 1 having the following composition after drying. /m ² with a coating device using a slide bead to form an ink-receiving layer. After cooling at 10° C. for 20 seconds, it was dried by blowing hot air of 30 to 55° C. on it. Further, on the ink-receiving layer, a release layer coating liquid 1 having the following composition was applied by a coating device using a hatched gravure roll so that the coating amount after drying was 0.02 g/m ² at the rotation speed of the hatched gravure roll. was adjusted and coated, and dried by blowing hot air at 45° C. to form a release layer. Next, a commercially available water-based acrylic resin type (emulsion type) adhesive (SE-6101, manufactured by Showa Denko KK) was applied to the side of the support on which the ink-receiving layer was not coated. An adhesive layer was formed by coating with a comma direct coater so as to have a thickness of m ² and drying to form an adhesive layer.

<Preparation of vapor phase silica dispersion>
4 parts of dimethyldiallylammonium chloride homopolymer (molecular weight: 9,000) and 100 parts of vapor-phase silica (average primary particle size: 7 nm, specific surface area: 300 m ² /g by BET method) were added to water to prepare a preliminary dispersion, and then the pressure was increased. A homogenizer treatment was performed to prepare a vapor-phase silica dispersion having a solid concentration of 20%. The average secondary particle size of the fumed silica contained in the dispersion was 135 nm. Using this fumed silica dispersion, an ink-receiving layer coating liquid 1 having the following composition was prepared.

<Ink receiving layer coating solution 1>
Gas-phase silica dispersion (as solid content of gas-phase silica) 100 parts Boric acid 4 parts Polyvinyl alcohol (degree of saponification 88%, average degree of polymerization 3500) 23 parts So that the solid content concentration of the coating liquid becomes 13% Adjusted with water.

<Release layer coating solution 1>
Aqueous emulsion for silicone resin formation 0.33 parts (POLON-MF-56 manufactured by Shin-Etsu Chemical Co., Ltd. Solid content concentration 40%)
Water 99.67 parts

(Example 2)
An ink jet recording pressure-sensitive adhesive label of Example 2 was obtained in the same manner as in Example 1, except that Release Layer Coating Solution 1 of Example 1 was replaced with Release Layer Coating Solution 2 below. The coating amount of the release layer after drying was 0.03 g/m ² .

<Release layer coating solution 2>
Aqueous emulsion for silicone resin formation 0.5 parts (POLON-MF-56 manufactured by Shin-Etsu Chemical Co., Ltd. Solid content concentration 40%)
Water 99.5 parts

(Example 3)
An ink-jet recording pressure-sensitive adhesive label of Example 3 was obtained in the same manner as in Example 1 except that Release Layer Coating Solution 1 of Example 1 was replaced with Release Layer Coating Solution 3 below. The coating amount of the release layer after drying was 0.05 g/m ² .

<Release layer coating solution 3>
Aqueous emulsion for silicone resin formation 0.83 parts (POLON-MF-56 manufactured by Shin-Etsu Chemical Co., Ltd. Solid content concentration 40%)
Water 99.17 parts

(Example 4)
An ink jet recording pressure-sensitive adhesive label of Example 4 was obtained in the same manner as in Example 1, except that Release Layer Coating Solution 1 of Example 1 was replaced with Release Layer Coating Solution 4 below. The coating amount of the release layer after drying was 0.08 g/m ² .

<Release layer coating solution 4>
Aqueous emulsion for silicone resin formation 1.35 parts (POLON-MF-56 manufactured by Shin-Etsu Chemical Co., Ltd. Solid content concentration 40%)
Water 98.65 parts

(Example 5)
An ink-jet recording pressure-sensitive adhesive label of Example 5 was obtained in the same manner as in Example 1 except that the release layer coating solution 1 of Example 1 was replaced with the following release layer coating solution 5. The coating amount of the release layer after drying was 0.1 g/m ² .

<Release layer coating solution 5>
Aqueous emulsion for silicone resin formation 1.66 parts (POLON-MF-56 manufactured by Shin-Etsu Chemical Co., Ltd. Solid content concentration 40%)
Water 98.34 parts

(Example 6)
An ink-jet recording pressure-sensitive adhesive label of Example 6 was obtained in the same manner as in Example 1, except that Release Layer Coating Solution 1 of Example 1 was replaced with Release Layer Coating Solution 6 below. The coating amount of the release layer after drying was 0.15 g/m ² .

<Release layer coating solution 6>
Aqueous emulsion for silicone resin formation 2.5 parts (POLON-MF-56 manufactured by Shin-Etsu Chemical Co., Ltd. Solid content concentration 40%)
Water 97.5 parts

(Example 7)
An ink-jet recording pressure-sensitive adhesive label of Example 7 was obtained in the same manner as in Example 1, except that Release Layer Coating Solution 1 in Example 1 was replaced with Release Layer Coating Solution 7 below. The coating amount of the release layer after drying was 0.08 g/m ² .

<Release layer coating solution 7>
Aqueous emulsion for silicone resin formation 1.35 parts (KM-9772 manufactured by Shin-Etsu Chemical Co., Ltd. solid content concentration 40%)
Water 98.65 parts

(Example 8)
An ink jet recording pressure-sensitive adhesive label of Example 8 was obtained in the same manner as in Example 1 except that the release layer coating solution 1 of Example 1 was replaced with the following release layer coating solution 8. The coating amount of the release layer after drying was 0.08 g/m ² .

<Release layer coating solution 8>
Aqueous emulsion for silicone resin formation 1.13 parts (IE-7170 manufactured by Dow Toray Industries, Inc. solid content concentration 48%)
Water 98.87 parts

(Comparative example 1)
An inkjet recording pressure-sensitive adhesive label of Comparative Example 1 was obtained in the same manner as in Example 1, except that Release Layer Coating Liquid 1 was not applied.

(Comparative example 2)
Release layer coating solution 1 in Example 1 was replaced with release layer coating solution 9 below, and the release layer was coated and dried, followed by heating at 100°C for 10 minutes. An adhesive label for inkjet recording was obtained. The coating amount of the release layer after drying was 0.08 g/m ² . The release layer-forming silicone emulsion used here requires a curing catalyst and is cured by an addition reaction.

<Release layer coating solution 9>
Aqueous emulsion for forming release silicone resin 1.3 parts (KM-3951 manufactured by Shin-Etsu Chemical Co., Ltd. solid content concentration 40%)
Silicone resin curing catalyst 0.07 parts (CAT-PM-10A manufactured by Shin-Etsu Chemical Co., Ltd. solid content concentration 20%)
Water 98.63 parts

(Comparative Example 3)
Release layer coating solution 1 of Example 1 was replaced with release layer coating solution 10 below, and the release layer was coated and dried, followed by heating at 100° C. for 10 minutes. An adhesive label for inkjet recording was obtained. The coating amount of the release layer after drying was set to 3.0 g/m ² by adjusting the number of rotations of the oblique line gravure roll.

<Release layer coating solution 10>
Aqueous emulsion for forming release silicone resin 47.6 parts (KM-3951 manufactured by Shin-Etsu Chemical Co., Ltd. solid content concentration 40%)
Silicone resin curing catalyst 2.4 parts (CAT-PM-10A Shin-Etsu Chemical Co., Ltd. solid content concentration 20%)
50 parts of water

The following evaluations were performed on the adhesive label for inkjet recording produced as described above. Table 1 shows the results.

<Image Uniformity>
A commercially available aqueous inkjet printer (EP-881A, manufactured by Seiko Epson Co., Ltd.) performs solid printing of cyan, magenta, yellow, and black, and the uniformity of the solid image area (granularity and gloss unevenness) is observed. was sensory evaluated.
⊚: Image uniformity is very high.
◯: The uniformity of the image is inferior to that of "A", but the level is not noticeable unless carefully observed.
Δ: The uniformity of the image is inferior to that of “◯”, but at a level that poses no practical problem.
x: The uniformity of the image is inferior to that of "Δ", and is at a practically problematic level.

<Easy Peelability>
After winding the adhesive label for inkjet recording into a roll so that the adhesive layer surface is in contact with the recording surface (the release layer surface in Examples 1 to 8 and Comparative Examples 2 and 3, and the ink receiving layer surface in Comparative Example 1). When the film was peeled off again, the state of the recording surface after peeling was visually observed and evaluated according to the following criteria.
A: Adhesion of the adhesive to the recording surface was not observed, and there was no change in gloss.
◯: Adhesion of the adhesive to the recording surface is not observed, but a slight change in gloss occurs.
Δ: Adhesion of the adhesive to the recording surface was slightly observed, and glossiness was changed, but there was no practical problem.
x: Adhesion of the adhesive to the recording surface is very often observed, or the adhesive is not peeled cleanly.

<Elongation at break of silicone resin>
Three types of silicone resin-forming aqueous emulsions and one type of releasable silicone resin-forming aqueous emulsion used in the preparation of release layer coating solutions 1 to 10 were used as aqueous emulsions 1 to 4 below, and the thickness when dried was 2 mm. It was coated on a polyethylene terephthalate film having a thickness of 100 μm (manufactured by Mitsubishi Chemical Corporation, total light transmittance of 89%) that had not been subjected to an easy-adhesion treatment. Aqueous emulsions 1 to 3 were dried at room temperature and then heated at 50° C. for 8 hours. Aqueous emulsion 4 was dried at room temperature, heated at 100° C. for 10 minutes, and then heated at 50° C. for 8 hours. The elongation at break of the dried silicone resin coating was measured according to JIS K 6251:2017. Table 1 shows the results.

<Aqueous emulsion 1>
Aqueous emulsion for silicone resin formation 100 parts (POLON-MF-56 manufactured by Shin-Etsu Chemical Co., Ltd. solid content concentration 40%)

<Aqueous emulsion 2>
Aqueous emulsion for silicone resin formation 100 parts (KM-9772 manufactured by Shin-Etsu Chemical Co., Ltd. solid content concentration 40%)

<Aqueous emulsion 3>
Aqueous emulsion for silicone resin formation 100 parts (IE-7170 manufactured by Dow Toray Industries, Inc. solid content concentration 48%)

<Aqueous emulsion 4>
Aqueous emulsion for forming release silicone resin 95.2 parts (KM-3951 manufactured by Shin-Etsu Chemical Co., Ltd. solid content concentration 40%)
Silicone resin curing catalyst 4.8 parts (CAT-PM-10A Shin-Etsu Chemical Co., Ltd. solid content concentration 20%)

From the results in Table 1, the adhesive label for inkjet recording of the present invention can be easily peeled off from the recording surface and the adhesive layer in contact with each other in a rolled state without using a release paper, and the printed image can be easily removed. It turns out that it is excellent in uniformity.

Claims (1)

An ink-receiving layer is provided on one side of the support, and a release layer containing a silicone resin having an elongation at break of 200% or more is provided on the ink-receiving layer. An adhesive label for inkjet recording having an agent layer.