JP2014065208A - Pressure bonded paper for inkjet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide pressure bonded paper for inkjet in which a pressure-sensitive adhesive layer capable of inkjet recording is provided and for which degradation of adhesive strength due to UV light irradiation is prevented.SOLUTION: In pressure bonded paper for inkjet, which is formed by providing a pressure-sensitive adhesive layer on at least one face of a substrate sheet, and which is capable of pseudo adhesion, the pressure bonded paper for inkjet is adjusted in such a way that by using a light source with a UV-light irradiation amount of 3.0 J/cmunder a condition that an irradiation distance (a distance between the light source and an object to be irradiated) is 0 mm, adhesive strength after treatment of a face of the pressure-sensitive adhesive layer under a condition of the irradiation distance of 100 mm, is 0.20 N/25 mm or more.

Description

  The present invention relates to a pressure-sensitive adhesive paper for inkjet that is suitably used for pressure-sensitive postcards, delivery slips, etc., and is provided with a pressure-sensitive adhesive layer on at least one side of a base sheet.

  For pressure-bonding postcards, delivery slips, and the like, so-called pre-glue type ink-jet paper is used. This inkjet pressure-sensitive adhesive paper is provided with a pressure-sensitive adhesive layer on at least one side of a base sheet, and images and the like can be recorded on the pressure-sensitive adhesive layer surface by an inkjet printer. And after crimping the confidential surfaces of two sheets of paper with a confidential surface (pressure sensitive adhesive layer) on one side, they can be peeled off when necessary, and the information printed on the confidential surface is confirmed by peeling it can. In addition, a single sheet may be folded in half with the pressure-sensitive adhesive layer on one side facing inward.

In addition to the functions required for pressure-sensitive adhesive paper, the above-mentioned pressure-sensitive adhesive paper for ink jet print quality, ink water resistance and weather resistance, and ink drying properties are the same as general ink-jet paper for which water-soluble ink is used. Ink back-off prevention performance is required. Among these qualities, the water resistance of the ink is particularly required from the viewpoint of preventing accidents due to rain or the like during mailing of the postcards.
This water resistance is the water resistance when ink jet recording is performed using a water-soluble ink having a direct dye or an acid dye as a colorant. In this type of water-soluble ink, the dye is water-solubilized by a salt of a sulfone group and / or a carboxyl group in the dye molecule, and the portion imparting water solubility in the dye molecule has a strong negative charge. . Conventionally, as a water resistance method for ink-jet recording images using water-soluble ink, a cationic polymer is included in the ink receiving layer to capture dye molecules in a charge, and a fan is installed between the two adjacent to each other as the water in the ink evaporates. It has been practiced to fix the dye molecules to the ink-jet receiving layer by using the Delwars force. Specific examples of the cationic polymer include many cationic compounds such as quaternized polyvinyl pyridine, polyethyleneimine, quaternized polyethyleneimine, polyallyl sulfone, dicyandiamide condensate, polyethylene polyamine polymer, polyallylamine, polydiallylamine and the like. A polymer is used.

As a method for making the ink jet recording image water-resistant with such a water-soluble ink, there is disclosed a method in which a polyvalent metal salt is contained in the ink receiving layer to insolubilize the ink dye (Patent Documents 1 and 2). Also disclosed is an inkjet paper in which an anionic coating layer is formed on a cationic polymer layer and a two-layer coating layer is provided on a support, and the water resistance of the ink is improved by the coating layer. (Patent Documents 3 and 4).
Ink-jet ink releasability with a pressure-sensitive adhesive layer on the support containing precipitated synthetic silica, acrylic ester emulsion dispersed with polyvinyl alcohol, cationic resin and natural rubber emulsion A pressure-sensitive recording sheet is disclosed (Patent Document 5).

JP-A-55-53591 JP-A-60-49990 Japanese Patent Laid-Open No. 5-124329 JP-A-7-149038 JP 2004-90593 A

However, the adhesive composition used for the pressure-sensitive adhesive layer of the pressure-bonded paper is an anion-dispersed system, and agglomeration occurs by reacting with a cationic polymer or a polyvalent metal salt, so these cannot be mixed at the same time, It is difficult to impart ink jet recording suitability (ink water resistance) to the pressure sensitive adhesive layer.
In addition, if the pressure-sensitive adhesive paper for ink-jet is a pressure-sensitive postcard, for example, variable information (individual information) such as the recipient's age and family structure is recorded by an ink-jet printer, and for recording fixed information such as frame lines and ruled lines, It is common to use offset presses that can print at high speeds on many types of paper. In the printing with this offset printing machine, when ink is cured by ultraviolet (UV) light irradiation after printing, so-called UV ink is used, the pressure-sensitive adhesive paper for inkjet is pressed after UV light irradiation. In the case of the pressure-sensitive adhesive paper for inkjet using the UV light, the adhesive strength is lowered by the UV light irradiation, and pseudo-adhesion cannot be performed, resulting in a problem that handling as the pressure-sensitive paper is inferior.

That is, the present invention has been made to solve the above-described problems, and provides a pressure-sensitive adhesive paper for inkjet provided with a pressure-sensitive adhesive layer capable of preventing a decrease in adhesive strength due to UV light irradiation and capable of inkjet recording. With the goal.

As a result of intensive studies, the present inventors have determined that the irradiation distance (distance between the light source and the object to be irradiated) is 0 mm and the light irradiation amount is 3.0 J / cm ² and the irradiation distance is 100 mm. And found that the above-mentioned problems can be solved by the pressure-sensitive adhesive paper for inkjet adjusted so that the adhesive strength after treating the pressure-sensitive adhesive layer surface is 0.20 N / 25 mm or more.

In order to achieve the above object, the pressure-sensitive adhesive paper for ink-jet recording of the present invention is a pseudo-adhesive ink-jet pressure-sensitive adhesive paper having a pressure-sensitive adhesive layer provided on at least one side of a substrate sheet. The adhesive strength after treating the pressure-sensitive adhesive layer surface under the condition of an irradiation distance of 100 mm using a light source with a UV light irradiation amount of 3.0 J / cm ² under the condition that the distance of the irradiated object is 0 mm is 0. It is adjusted to be 20 N / 25 mm or more.

  The pressure-sensitive adhesive layer contains pressure-sensitive adhesive composite fine particles in which emulsion fine particles are aggregated with a polyurea-polyurethane resin, silica, and a cationic polymer or a polyvalent metal salt. Is preferred.

The pressure-sensitive adhesive layer preferably further contains a binder.
The pressure-sensitive adhesive composite fine particles are preferably 1 to 100 parts by mass (solid content), more preferably 1 to 10 parts by mass (solid content) of the water-dispersible isocyanate compound with respect to 100 parts by mass (solid content) of the emulsion type adhesive. Solid content) is added.
It is preferable that the pressure-sensitive adhesive layer further contains a water-based acrylic resin emulsion containing acrylic acid ester and acrylonitrile as monomer components.

  According to the present invention, an ink-jet pressure-sensitive adhesive paper having a pressure-sensitive adhesive layer capable of ink-jet recording and preventing a decrease in adhesive strength due to UV light irradiation can be obtained.

Hereinafter, the pressure-sensitive adhesive paper for ink jet according to the embodiment of the present invention will be described. The pressure-sensitive adhesive layer for inkjet recording of the present invention is provided with a pressure-sensitive adhesive layer on at least one side of a base sheet, and the irradiation amount of UV light is 3. on the condition that the irradiation distance (distance between the light source and the irradiated object) is 0 mm. By using a light source of 0 J / cm ² , the adhesive strength after processing the pressure-sensitive adhesive layer surface under the condition of an irradiation distance of 100 mm is adjusted so as to be 0.20 N / 25 mm or more. Even in the case of using UV ink in printing, the decrease in adhesive strength due to UV light irradiation is prevented, and pseudo-adhesion cannot be performed and the problem of poor handling as a pressure-sensitive paper does not occur.

The pressure-sensitive adhesive layer contains pressure-sensitive adhesive composite fine particles in which emulsion fine particles are aggregated with a polyurea-polyurethane resin, silica, and a cationic polymer or a polyvalent metal salt. Is preferred. As the pressure-sensitive adhesive composite fine particles, for example, those described in JP-A No. 2007-291326 can be used.
The pressure-sensitive adhesive layer contains pressure-sensitive adhesive composite fine particles in which fine particles of an emulsion-type adhesive are aggregated by a polyurea-polyurethane resin, silica, and a cationic polymer or a polyvalent metal salt. Therefore, it is preferable because a decrease in adhesive strength due to UV light irradiation is effectively prevented, and pseudo-adhesion cannot be performed and the problem of poor handling as a pressure-sensitive paper does not occur.
When a natural rubber emulsion is used for the pressure-sensitive adhesive layer, the isoprene-based compound, which is the main component of the natural rubber emulsion, has a double bond in its main chain. It is presumed that the adhesive strength is remarkably lowered by UV light irradiation because it absorbs light and cleaves. Further, in printing on an offset printing press using UV ink, ozone may be generated by UV light irradiation, and it is presumed that double bonds are similarly cleaved by this ozone and the adhesive strength is lowered.
On the other hand, the pressure-sensitive adhesive layer contains pressure-sensitive adhesive composite fine particles in which fine particles of an emulsion-type adhesive are aggregated with a polyurea-polyurethane resin, silica, and a cationic polymer or a polyvalent metal salt. In this case, the pressure-sensitive adhesive composite fine particles are in a state where the surface of the emulsion-type adhesive is covered with a polyurea-polyurethane resin. Therefore, even if it irradiates with UV light, it is estimated that the adhesive strength is hardly lowered due to the cleavage of the double bond of the emulsion type adhesive.
In particular, when the main component of the emulsion-type adhesive is an acrylic resin described later,
Since the acrylic resin does not have a double bond in its main chain, it is presumed that the adhesive strength is not easily lowered by the cleavage of the double bond even when irradiated with UV light.

<Pressure-sensitive adhesive composite fine particles>
The pressure-sensitive adhesive composite fine particles are obtained by adding a water-dispersible isocyanate compound to an emulsion-type adhesive and heating it to react with the water-dispersible isocyanate compound to form a polyurea-polyurethane resin.
The mechanism by which the pressure-sensitive adhesive composite fine particles become pressure-sensitive adhesive is presumed as follows. The water-dispersible isocyanate compound dispersed in water is dispersed in water in the same manner as the emulsion-type adhesive, and when heated, active hydrogen groups inevitably contained in the emulsion-type adhesive (for example, It is considered that this emulsion type adhesive is agglomerated as a result of reaction with unreacted hydroxyl group, carboxyl group, amino group and the like.
It is considered that the water-dispersible isocyanate compound reacts with these active hydrogen groups on the surface of the emulsion type adhesive to form a polyurea-polyurethane resin to cover these surfaces and reduce the anionicity of the surface. When a deformation pressure is applied to the fine particles having such a form, the polyurea-polyurethane resin covering the surface is destroyed and the emulsion type adhesive is exposed on the surface, so that it is considered to exhibit tackiness or adhesiveness.

<Emulsion type adhesive>
As the emulsion type adhesive, acrylic, rubber, urethane, EVA, silicon and the like can be suitably used, but acrylic resin is particularly preferable since it is excellent in heat resistance, transparency, weather resistance and the like.
The acrylic resin is polyacrylonitrile, polyacrylamide, polyacrylic acid and / or an ester thereof (hereinafter referred to as “PA resin system”), or polymethacrylic acid and / or an ester thereof (hereinafter referred to as “PMA-resin system”). This is a resin whose main component is. In particular, the acrylic resin is preferably PA resin, PMA resin, or a copolymer of PA resin and PMA resin. The ester group in the ester may be a long chain ester group such as a diethylhexyl group as well as a methyl group, an ethyl group, and a butyl group, but a methyl group is preferably used. Further, a copolymer type resin in which vinyl acetate ester or the like is mixed in addition to acrylic acid or methacrylic acid can be used for the main chain of the acrylic resin.
The particle size (volume 50% average particle size (D50)) of the emulsion-type adhesive is about 300 to 900 nm.

  The pressure-sensitive adhesive composite fine particles may be contained in a mixing ratio of 1 to 100 parts by mass (solid content) of the following water-dispersible isocyanate compound with respect to 100 parts by mass (solid content) of the emulsion type adhesive. If the proportion of the water-dispersible isocyanate compound exceeds 100 parts by mass with respect to 100 parts by mass of the emulsion-type adhesive, the adhesive strength may decrease. On the other hand, when the ratio of the water-dispersible isocyanate compound is less than 1 part by mass, the coverage with the polyurea-polyurethane resin is deteriorated, and it may be difficult to aggregate the emulsion-type adhesive fine particles. More preferably, it is 1-10 mass parts (solid content) of a water-dispersible isocyanate compound with respect to 100 mass parts (solid content) of an emulsion type adhesive.

<Water-dispersible isocyanate compound>
A water-dispersible isocyanate compound is a polymer in which a hydrophilic functional group such as alkylene oxide is added to a polymer of a polyvalent isocyanate compound such as a hexamethylene diisocyanate compound (HDI), and is compatible with water. ing.
Examples of the water-dispersible isocyanate compound include those obtained by adding a nonionic functional group such as ethylene oxide to an aliphatic, alicyclic, or aromatic polyisocyanate compound or a derivative thereof. Specific examples of water-dispersible polyisocyanate compounds are disclosed in Japanese Patent Publication No. 7-30160, and are monovalent or polyvalent containing at least one aliphatic polyisocyanate compound and at least one polyether chain having at least 10 ethylene oxide units. A reaction product with a valent nonionic polyalkylene ether alcohol; disclosed in JP-A-7-109327, a polyether chain containing an average of 7 to 25 alkylene oxide units in which at least 70 mol% is ethylene oxide units; Examples thereof include, but are not limited to, a partially urethanized composition of a monovalent or polyhydric alcohol and 2,4- and / or 2,6-diisocyanatotoluene.

  The isocyanate compound used to obtain the water-dispersible polyisocyanate compound mainly includes aliphatic, alicyclic, or aromatic isocyanate compounds and derivatives thereof, among which aliphatic or alicyclic isocyanates. Compounds and derivatives thereof are preferred.

（式中、Ｒ^１、Ｒ^２及びＲ^３は、出発ジイソシアネート化合物からイソシアネート化合物基を除去することによって得られる同一又は異なる炭化水素基を表す。） Examples of aliphatic or alicyclic polyisocyanate compounds include
1) Isocyanurate group-containing polyisocyanate compounds based on aliphatic and / or alicyclic diisocyanate compounds; 1,6-diisocyanatohexane and / or 1-isocyanato-3,3,5-trimethyl-5 Isocyanatomethyl-cyclohexane (isophorone diisocyanate compound = IPDI) is an isocyanatoisocyanurate. The production of such compounds is described, for example, in German Patent 2,616,416, European Patent Publication 3,765, 10,589, 47,452, U.S. Pat. No. 4,288,586. No. 4,324,879. Moreover, the isocyanurate group containing polyisocyanate compound which made the base the other aliphatic and / or alicyclic diisocyanate compound represented by a following formula is also mentioned. This is a simple tris-isocyanatoalkyl- (or -cycloalkyl-) isocyanurate or a mixture of it and its higher homologue (containing more than one isocyanurate ring).

(Wherein R ¹ , R ² and R ³ represent the same or different hydrocarbon groups obtained by removing isocyanate compound groups from the starting diisocyanate compound.)

（式中Ｒ^４及びＲ^５はＲ^１及びＲ^２と同じ。特にはヘキサメチレンジイソシアネート化合物及び／又はＩＰＤＩからイソシアネート化合物基を除去することによって得られる炭化水素基を表す。）が挙げられる。
ウレツトジオンジイソシアネート化合物は単独又は他の脂肪族ポリイソシアネート化合物、特に上記１）に記載されたイソシアヌレート基含有ポリイソシアネート化合物と混合物として存在することができる。 Examples of aliphatic or alicyclic polyisocyanate compounds include
2) A uretdione diisocyanate compound having an isocyanate compound group bonded to an aliphatic and / or alicyclic group represented by the following formula:

(Wherein R ⁴ and R ⁵ are the same as R ¹ and R ^2, and particularly represent a hydrocarbon group obtained by removing an isocyanate compound group from a hexamethylene diisocyanate compound and / or IPDI).
The uretdione diisocyanate compound can be present alone or as a mixture with other aliphatic polyisocyanate compounds, in particular with the isocyanurate group-containing polyisocyanate compounds described in 1) above.

（式中、Ｒ^６はＲ^１に既に記載した意味を有し、特に、生成物が１，６−ジイソシアナトヘキサン及び二酸化炭素から生成せしめられた場合のヘキサメチレン基を表す。）が挙げられる。 Examples of aliphatic or alicyclic polyisocyanate compounds include
3) A biuret group-containing polyisocyanate compound having an isocyanate compound group bonded to an aliphatic group, that is, tris- (6-isocyanatohexyl) -biuret or a mixture thereof and its higher homologues;
4) Urethane and / or allophanate group-containing polyisocyanate compounds having aliphatic or alicyclically bound isocyanate compound groups, that is, an excess amount of hexamethylene diisocyanate compound or IPDI is converted to a simple polyhydric alcohol (for example, trimethylolpropane, Obtained by reacting with glycerin, 1,2-dihydroxypropane or mixtures thereof;
5) Oxadiazinetrione group-containing polyisocyanate compound having an isocyanate compound group bonded to an aliphatic or alicyclic group represented by the following formula

(Wherein R ⁶ has the meaning already described for R ¹ and in particular represents a hexamethylene group when the product is formed from 1,6-diisocyanatohexane and carbon dioxide). It is done.

  The aliphatic or alicyclic polyisocyanate compounds exemplified in the above 1) to 5) can be present alone or in admixture as desired. The “aliphatic polyisocyanate compound” in the present invention represents a polyisocyanate compound in which the isocyanate compound is bonded to an aliphatic or alicyclic carbon atom. Examples of the aromatic polyisocyanate compound include 2,4- and / or 2,6-toluene diisocyanate, 4,4′-diphenylmethane diisocyanate, and the like.

  Examples of nonionic functional groups such as ethylene oxide added to the polyisocyanate compound include ethylene oxide unit-containing polyether alcohols. For the production of suitable polyether alcohols, monovalent or polyvalent initiator molecules such as methanol, n-butanol, cyclohexanol, 3-methyl-3-hydroxymethyloxetane, phenol, resorcinol, ethylene glycol, propylene glycol An alkoxylated product of aniline, trimethylolpropane or glycerin (containing at least one polyether chain containing at least 10, generally 10 to 70, preferably 15 to 65 ethylene oxide units) is used. The production of the water-dispersible isocyanate compound is carried out by preparing a hydrophilic compound containing an isocyanate compound-reactive group in the aliphatic, alicyclic, or aromatic polyisocyanate compound or derivative thereof, preferably the nonionic ethylene oxide unit. This is accomplished by reacting the containing polyether alcohol at an NCO / OH equivalent ratio of at least about 1: 1, preferably from about 2: 1 to about 1000: 1. In particular, when polyhydric polyether alcohols are used, an NCO / OH equivalent ratio of at least about 2: 1 is used. The water-dispersible isocyanate compound is generally produced at a medium to high temperature of 50 to 130 ° C.

Furthermore, in addition to the water-dispersible isocyanate compound, polyols, polyamines, and the like can be added to the reaction system in which the emulsion adhesive and the water-dispersible isocyanate are mixed. Examples of the polyol include polyhydric alcohols and alkylene oxide adducts of polyhydric alcohols. Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, resorcinol, Examples thereof include compounds having two or more hydroxyl groups such as polysaccharides such as glycerin, diglycerin, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, diglycerin, methylglucoside, sorbitol, and sucrose. Examples of polyamines include alkylene polyamines such as ethylenediamine, propylenediamine, hexamethylenediamine, octamethylenediamine, paraphenylenediamine, piperazine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine, monoethanolamine, diethanolamine, triethanolamine, and isopropanol. -Alkanolamines such as luamine, isobutanolamine and the like.
In the present invention, the NCO group ratio (NCO%) in the water-dispersible isocyanate compound composition is 6 to 24%, more preferably 8 to 20%. Examples of such water-dispersible isocyanate compound products include Takenate WD series manufactured by Mitsui Chemicals, and Bihijur series manufactured by Sumika Bayer Urethane. As content of a water-dispersible isocyanate compound, it is about 0.01-1 times (mass ratio) with respect to an adhesive agent.

The pressure-sensitive adhesive composite fine particles may contain various crosslinking agents. Various crosslinking agents can be added to a reaction system in which an emulsion-type adhesive and a water-dispersible isocyanate are mixed to form composite particles.
Examples of the crosslinking agent include polyvalent amines and polyvalent hydroxy compounds. Examples of the polyvalent amine include aliphatic polyvalent amines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,3-propylenediamine and hexamethylenediamine, and aromatics such as phenylenediamine, diaminonaphthalene and xylenediamine. Examples thereof include alicyclic polyamines such as polyamine and piperazine, and these can be used alone or in combination. Examples of the polyvalent hydroxy compound include aliphatic or aromatic polyhydric alcohols, hydroxy polyesters, hydroxy polyalkylene ethers, and alkylene oxide adducts of polyvalent amines. These crosslinking agents can be added in an appropriate number of parts according to the physical properties of the target pressure-sensitive adhesive composite fine particles, and are, for example, about 0.01 to 1 times (mass ratio) of the water-dispersed isocyanate compound.

The pressure-sensitive adhesive composite fine particles can be produced, for example, as follows. First, water is added to 100 parts of emulsion-type adhesive in solid content, and diluted to a concentration of 10 to 60% by mass (more preferably 15 to 50% by mass). If the concentration of the emulsion-type adhesive is too high, aggregation tends to occur when the composite fine particles are formed, and if the concentration is too low, the coverage with the water-dispersible isocyanate compound decreases. The emulsion type adhesive may be diluted with alcohol or the like.
A water-dispersible isocyanate compound is added to the emulsion-type adhesive diluted solution to obtain a dispersion. The addition amount of the water-dispersible isocyanate compound is 1 to 100 parts by mass (solid content), more preferably 1 to 10 parts by mass (solid content) with respect to 100 parts by mass of the emulsion type adhesive (solid content). If the addition amount of the water-dispersible isocyanate compound is small, sufficient coverage cannot be improved, and if the addition amount is too large, the adhesiveness of the adhesive is lowered.
Next, in order to promote the conversion of the isocyanate compound into a resin, the dispersion is heated and stirred. Although the water-dispersible isocyanate compound reacts with the emulsion-type adhesive even at room temperature (25 ° C.), it may be heated in the range of room temperature to 90 ° C. (more preferably 50 ° C. to 85 ° C.) in order to obtain sufficient coverage. . When the temperature of the liquid is below room temperature, the reaction of the isocyanate is slowed to make the composite fine particles insufficient, and when it is 90 ° C. or higher, the reaction of the isocyanate is too fast and aggregation / residue may occur in the reaction liquid. is there. The warming time varies depending on the warming temperature, but is usually about 1 to 6 hours. In addition, although water | moisture content evaporates with heating, the water for evaporation is added suitably so that the density | concentration of the solid content in a dispersion liquid may be hold | maintained at about 15-60 mass%, Preferably it is about 20-50 mass%. It is preferable.

The dispersion after the warming reaction is cooled to room temperature to complete the formation of composite fine particles. Composite fine particles are obtained in a slurry state (concentration of solid content of about 15 to 60% by mass) dispersed in water. In this slurry, the composite fine particles exist as single particles or as a result of gently secondary aggregation of the composite fine particles. In order to obtain appropriate composite fine particles, it is necessary to be dispersed in water at the stage where the composite fine particles are formed. When the water is removed by heating to the boiling point of water at this stage or in the previous stage, the emulsion-type adhesive becomes a huge lump, has pressure sensitivity, and cannot form composite fine particles of an appropriate size. .
The particle size of the composite fine particles (including secondary aggregates of the composite fine particles) affects the storage stability and the pressure required to destroy the composite fine particles. Although not intended, the 50% volume average particle diameter (D50) is preferably 5 μm to 500 μm, more preferably 10 μm to 300 μm. In particular, it is preferable that the D50 of the composite fine particles exceeds 20 μm because the stability of the pressure-sensitive adhesive layer coating material is good (viscosity change after preparation is small).
If the particle size of the composite fine particles is small, sufficient adhesion cannot be obtained, and if the particle size is too large, the composite fine particles may be destroyed during the operation in forming the pressure-sensitive adhesive layer. Moreover, D50 can be measured using a measuring apparatus using a Coulter method or a laser diffraction method.

<Pressure sensitive adhesive layer>
The pressure-sensitive adhesive layer preferably contains the pressure-sensitive adhesive composite fine particles, silica, and a cationic polymer or a polyvalent metal salt. By setting the pressure sensitive adhesive layer to the above composition, it becomes easy to perform ink jet recording on the pressure sensitive adhesive layer. Furthermore, since the pressure-sensitive adhesive composite fine particles are formed by agglomerating the emulsion type adhesive fine particles with a polyurea-polyurethane resin and at least partially being coated, the reactive fine particles are reacted with the cationic polymer or the polyvalent metal salt to be aggregated. Hard to happen. For this reason, it is easy to mix | blend the cationic polymer and polyvalent metal salt which show ink water resistance with a pressure sensitive adhesive layer.
Furthermore, it is preferable because a decrease in adhesive strength due to UV light irradiation is effectively prevented, and pseudo-adhesion cannot be performed and the problem of poor handling as a pressure-sensitive paper does not occur.

  The cationic polymer and the polyvalent metal salt are added to bind to an anionic dye such as a direct dye or an acid dye contained in the water-soluble ink and to be firmly immobilized (ink fixing). As such a cationic polymer, for example, polyamines, polyallylamines, dicyandiamide condensates, polydimethyldiallylammonium, polyethyleneimines, epichlorohydrin derivatives and the like can be used. Examples of the polyvalent metal salts that can be used include calcium and magnesium hydrochlorides, nitrates, sulfates, and lactates. In the present invention, a cationic polymer is preferred because it binds to an anionic dye and is strongly immobilized (ink fixing), and the water resistance of the ink jet recorded image is particularly good.

In the present invention, it is preferable to use synthetic amorphous silica as the silica. Further, as the synthetic amorphous silica, gel method silica is desirable. “Gel silica” is obtained by agglomerating in a state in which the growth of primary particles is suppressed by advancing the neutralization reaction of sodium silicate and mineral acid (usually sulfuric acid) in an acidic pH 2-6 region. Wet method synthetic amorphous silica fine particles. Compared with precipitated silica (manufactured by proceeding neutralization reaction of sodium silicate and mineral acid in an alkaline pH range), gel method silica has a longer reaction time after agglomeration and strong bond between primary particles. , The pore volume tends to increase. For this reason, it is excellent in ink absorptivity and abrasion resistance.
The synthetic amorphous silica preferably has a volume 50% average particle diameter (D50) of 6 μm or more in order to obtain a target adhesive strength. When the D50 of the synthetic amorphous silica is less than 6 μm, the adhesive strength may decrease. D50 of the above-mentioned synthetic amorphous silica can be measured by MASTER SIZER S manufactured by MALVERN using a laser diffraction method.

  The oil absorption amount of the synthetic amorphous silica is not particularly limited, but is preferably 200 ml / 100 g or more and 500 ml / 100 g or less, and more preferably 250 ml / 100 g or more and 400 ml / 100 g or less. If the oil absorption is less than 200 ml / 100 g, the ink receiving layer may not have sufficient ability to hold ink, and the printed portion may have poor scratch resistance and ink absorbability. When the oil absorption exceeds 500 ml / 100 g, when the pigment is dispersed, the viscosity of the paint may increase and the dispersibility of the paint may deteriorate. The oil absorption amount can be measured by a method defined in JIS-K5101.

The pressure-sensitive adhesive layer may further contain a binder, an auxiliary adhesive, a tilting agent for preventing destruction of the composite fine particles due to pressurization (inadvertent pressurization) other than making it adhereable to the adherend. Good. In particular, the pressure sensitive adhesive layer preferably contains a binder.
The ratio of each component in the pressure-sensitive adhesive layer is appropriately selected depending on the configuration of the pressure-sensitive adhesive composite fine particles and is not particularly limited, but is 100 parts by weight (solid content) of the pressure-sensitive adhesive composite fine particles. , Cationic polymer or polyvalent metal salt 30 to 150 parts by mass, silica 50 to 200 parts by mass.
When a pressure sensitive adhesive layer contains a binder further, it is 10-50 mass parts of binders with respect to 100 mass parts (solid content) of pressure sensitive adhesive fine particles. In addition, 10 to 50 parts by mass of the auxiliary adhesive, 0 to 50 parts by mass of the stilting agent, and 0 to 50 parts by mass of the other additive are added to 100 parts by mass (solid content) of the pressure-sensitive adhesive composite fine particles as necessary. You may make it contain.

  In the present invention, as the binder, a commonly used water-soluble polymer or hydrophobic polymer emulsion or the like can be appropriately used. Specific examples of the binder include cellulose derivatives such as polyvinyl alcohol, polyvinyl acetal, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, starch and derivatives thereof, polyacrylic acid soda, polyvinyl pyrrolidone, acrylic acid amide / acrylic acid ester copolymer, Highly water-soluble such as acrylic acid amide / acrylic acid ester / methacrylic acid copolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein Molecule, polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylate ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, Len / vinyl acetate copolymer, can be used styrene / butadiene / emulsion of a hydrophobic polymer of the acrylic copolymer. In the present invention, the binder is preferably polyvinyl alcohol.

  When an auxiliary adhesive such as an aqueous acrylic resin emulsion containing acrylic acid ester and acrylonitrile as monomer components is further added to the pressure sensitive adhesive layer, the adhesive strength is improved. As an auxiliary adhesive, it is effective to use an aqueous acrylic resin emulsion containing acrylic acid ester and acrylonitrile as monomer components because it has high resistance to deterioration due to heat and oxidation, has high adhesive strength, and is difficult to cause blocking. .

  In the present invention, a tilting agent is preferably included in the pressure-sensitive adhesive layer in order to prevent destruction of the composite fine particles due to press, except when the adhesive is allowed to adhere to an adherend. As the tilting agent, pulp powder, raw starch powder, plastic pigment and the like can be used. Since these stilting agents have an appropriate cushioning property, it is possible to control the adhesive force at the time of pressurization for adhesion, and a long time has passed since they are adhered to a sheet surface that does not have a pseudo adhesive layer. In this case, it contributes to peeling without destroying the sheet surface having no pseudo adhesive layer.

  For the pressure sensitive adhesive layer, pigment dispersant, thickener, water retention agent, lubricant, antifoaming agent, foam suppressant, mold release agent, antiseptic, water resistant agent, surfactant, Auxiliaries such as pH adjusters can be added as appropriate.

As a method for forming the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer coating is applied to the base sheet by a normal coating method such as a bar blade coater, a vent blade coater, a curtain coater, and an air knife coater. Good. The pressure-sensitive adhesive layer coating material can be prepared by adding the above-described components to the slurry of the adhesive composite fine particles as necessary.
The coating amount after drying of the pressure-sensitive adhesive layer may be appropriately set according to the desired adhesive strength and product form, and is not limited, but is preferably 3 to ²⁰ g / m ² , for example. it is a 5~15g / ^{m 2} about. After coating, the paper surface temperature may be dried at about 40 ° C to 120 ° C.

<Inkjet pressure-sensitive paper>
The inkjet pressure-sensitive adhesive paper of the present invention is formed by providing a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composite fine particles on at least one surface of a base sheet.
The substrate sheet is not particularly limited as long as it is in the form of a sheet such as fine paper, coated paper, recycled paper, and synthetic paper.
When the base sheet is paper, the main components of the paper are pulp and an internal filler. As the pulp, any known pulp can be used. For example, hardwood bleached kraft pulp, hardwood unbleached kraft pulp, softwood bleached kraft pulp, softwood unbleached kraft pulp, hardwood bleached sulfite pulp, hardwood unbleached sulfite pulp, softwood bleached sulfite pulp, softwood unbleached sulfite pulp, wood Pulp made by chemically treating fiber raw materials such as cotton, hemp, and leather can be used. In addition, ground wood pulp that mechanically pulped wood and chips, chemimechanical pulp mechanically pulped after soaking chemicals into wood and chips, and pulp with a refiner after digesting the chips until they become slightly soft Thermomechanical pulp that has been made into a material can also be used. It is preferable to use hardwood bleached kraft pulp having high whiteness and excellent texture in the ink jet pressure-sensitive paper of the present invention.

  Pulp made from used paper, that is, cuts that occur in bookbinding, printing plants, cutting offices, damaged paper, narrow whites, whites, whites, whites, whites, etc. High-quality printed paper such as high-quality paper, high-quality coated paper that has been copied; old paper written with water-based ink, oil-based ink, pencil, etc .; printed high-quality paper, high-quality coated paper, medium-quality paper, medium-quality coated paper, etc. It is also possible to use pulp obtained by disaggregating old paper such as medium-sized paper, medium-coated paper, and reprinted paper.

  When the coating material to be the pressure-sensitive adhesive layer is applied to the substrate sheet and dried, the adhesion between the pressure-sensitive adhesive layer and the substrate sheet after drying the coating material becomes strong. On the other hand, the surface of the pressure-sensitive adhesive layer after drying the paint can be pseudo-bonded by applying pressure to the surfaces of the pressure-sensitive adhesive layers. And, by using the pressure-sensitive adhesive layer of the present invention, this pseudo-adhesive force does not increase with time and it becomes difficult to peel off when necessary, no problem of enhancement occurs, and the pseudo-adhesive force Stable over a long period of time. For this reason, the pressure-sensitive adhesive paper for inkjet of the present invention can be suitably used for confidential postcards and delivery slips. In addition, confidential postcards manufactured using this inkjet pressure-sensitive adhesive paper are less expensive than confidential postcards in which an expensive resin film is laminated and pseudo-adhered instead of the pressure-sensitive adhesive layer.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by this. In the examples, “parts” and “%” represent “parts by mass” and “% by mass”, respectively, unless otherwise specified.

[Example 1]
In order to produce pressure sensitive adhesive composite fine particles, 100 parts (solid content) of an emulsion type adhesive (acrylic / vinyl acetate copolymer aqueous emulsion, trade name: AT-39, solid content 60%, manufactured by Seiden Chemical Co., Ltd.) After dilution by adding water, the mixture was kept at 25 ° C. with stirring. To this was added 2.5 parts of a water-dispersible isocyanate compound (trade name: WD-725, solid content: 100%, NCO% = 15.8%, manufactured by Mitsui Chemicals) to obtain a dispersion, which was stirred at 25 ° C. Hold for 30 minutes. The dispersion was heated to 55 ° C. and held for 3 hours while appropriately adding water for evaporation, and further heated to 80 ° C. and held for 1 hour while appropriately adding water for evaporation. The agent and the water-dispersible isocyanate compound were converted into a polyurea-polyurethane resin.
In this resinification, the 50% volume average particle size (D50) of the reaction solution was measured with a laser diffraction particle size distribution meter (manufactured by MALVERN, MASTER SIZER S), and it was confirmed that the reaction progressed by increasing D50. did. After completion of resinification, the reaction solution was cooled to obtain a slurry of pressure-sensitive adhesive composite fine particles (solid content 30%). The D50 of the pressure-sensitive adhesive composite fine particles was 20 μm. On the other hand, D50 of the emulsion-type adhesive (acrylic / vinyl acetate copolymer aqueous emulsion) before resinification is 0.6 μm, and the slurry obtained as described above has fine particles of the emulsion-type adhesive composed of polyurea-polyurethane. It was confirmed that the agglomeration was caused by the resin (in some cases, it was estimated that the pressure-sensitive adhesive composite fine particles were gradually agglomerated secondary).

Next, using the obtained pressure-sensitive adhesive composite fine particle slurry, a pressure-sensitive adhesive layer coating material having the following composition was prepared. The above-mentioned paint was applied with a bar blade coater on one side of a high-quality paper having a basis weight of 110 g / m ^{2 so} that the coating amount after drying was 10 g / m ^2, and an inkjet pressure-sensitive paper was prepared.
<Paint for pressure sensitive adhesive layer>
Adhesive composite fine particle slurry (solid content 30%): 100.0 parts Cationic polymer (trade name: DK6872, solid content 50%,
(Made by Seiko PMC): 50.0 parts Synthetic amorphous silica (trade name: AY-601, volume 50% average particle diameter (D50)
= 9.7 μm, manufactured by Tosoh Silica Co., Ltd .: 100.0 parts Binder (polyvinyl alcohol, trade name: PVA-117)
10% solid content aqueous solution, manufactured by Kuraray Co., Ltd .: 20.0 parts Auxiliary adhesive (acrylic resin emulsion containing acrylic ester and acrylonitrile as monomers, trade name: Nipol LX874B,
Solid content 50%, manufactured by Nippon Zeon Co., Ltd.): 20.0 parts Stilting agent (starch particles, trade name: Actinis, manufactured by Rocket):
20.0 parts Release agent (trade name: LS106, manufactured by Kao Corporation): 10.0 parts

[Example 2]
When producing pressure-sensitive adhesive composite fine particles, WD-730 (solid content 100%, NCO% = 18.2%, manufactured by Mitsui Chemicals, Inc.) was used instead of WD-725 as the water-dispersible isocyanate compound. Except for the above, an inkjet pressure-sensitive adhesive paper was produced in the same manner as in Example 1. D50 of this pressure-sensitive adhesive composite fine particle was 18 μm.
[Example 3]
A pressure-sensitive adhesive layer was prepared in the same manner as in Example 1 except that when the pressure-sensitive adhesive layer coating material was prepared, the amount of silica was changed to 180 parts.
[Example 4]
Inkjet pressure-sensitive adhesive paper was prepared in the same manner as in Example 1 except that the amount of the auxiliary adhesive (LX874B) was changed to 25 parts.

[Example 5]
A pressure-sensitive adhesive layer was prepared in the same manner as in Example 1 except that no binder was added when the pressure-sensitive adhesive layer coating was prepared.
[Example 6]
A pressure-sensitive adhesive layer was prepared in the same manner as in Example 1 except that 50 parts of a polyvalent metal salt (magnesium sulfate) was blended in place of the cationic polymer when preparing the pressure-sensitive adhesive layer coating.
[Example 7]
A pressure-sensitive adhesive composite paper was produced in the same manner as in Example 1 except that the amount of the water-dispersible isocyanate compound (WD-725) was changed to 1.5 parts when producing the pressure-sensitive adhesive composite fine particles. . D50 of this pressure-sensitive adhesive composite fine particle was 15 μm.
[Example 8]
A pressure-sensitive adhesive composite paper was produced in the same manner as in Example 1 except that the amount of the water-dispersible isocyanate compound (WD-725) was changed to 0.5 part when producing the pressure-sensitive adhesive composite fine particles. . The D50 of the pressure-sensitive adhesive composite fine particles was 1 μm.
[Example 9]
A pressure-sensitive adhesive composite paper was produced in the same manner as in Example 1 except that the amount of the water-dispersible isocyanate compound (WD-725) was changed to 4.5 parts when producing pressure-sensitive adhesive fine particles. . The D50 of the pressure-sensitive adhesive composite fine particles was 25 μm.

[Example 10]
A pressure-sensitive adhesive composite paper was produced in the same manner as in Example 1 except that the amount of the water-dispersible isocyanate compound (WD-725) was changed to 10.0 parts when the pressure-sensitive adhesive composite fine particles were produced. . D50 of this pressure-sensitive adhesive composite fine particle was 31 μm.
[Example 11]
A pressure-sensitive adhesive composite paper was produced in the same manner as in Example 1 except that the amount of the water-dispersible isocyanate compound (WD-725) was changed to 15.5 parts when producing the pressure-sensitive adhesive composite fine particles. . The D50 of this pressure-sensitive adhesive composite fine particle was 36 μm.
[Example 12]
A pressure-sensitive adhesive composite paper was produced in the same manner as in Example 1 except that the amount of the water-dispersible isocyanate compound (WD-725) was changed to 20.0 parts when producing the pressure-sensitive adhesive composite fine particles. . D50 of this pressure-sensitive adhesive composite fine particle was 40 μm.
[Example 13]
When producing pressure-sensitive adhesive composite fine particles, an emulsion-type adhesive (acrylic copolymer aqueous emulsion, trade name: AT-85, solid content 60%, Seiden Chemical Co., Ltd.) instead of AT-39 as an emulsion-type adhesive. Inkjet pressure-sensitive paper was prepared in the same manner as in Example 1 except that the product was used. The D50 of the pressure-sensitive adhesive composite fine particles was 20 μm.

[Comparative Example 1]
When preparing the coating for the pressure sensitive adhesive layer, an emulsion type adhesive (acrylic / vinyl acetate copolymer aqueous emulsion, trade name: AT-39, solid content 60%, Syden, instead of the above-mentioned adhesive composite fine particle slurry. A pressure-sensitive adhesive paper for inkjet was produced in the same manner as in Example 1 except that 100 parts (made by chemical) (solid content) was used as it was.
[Comparative Example 2]
When preparing the pressure-sensitive adhesive layer coating material, a modified natural rubber emulsion adhesive (trade name: GS5-50, solid content 60%, manufactured by Quay Kasei) was used in place of the adhesive composite fine particle slurry. Except that, an ink jet pressure-sensitive paper was prepared in the same manner as in Example 1. In Comparative Example 2, the water-dispersible isocyanate compound (trade name: WD-725) was mixed with a modified natural rubber emulsion adhesive in the same manner as in each Example. The D50 of the pressure-sensitive adhesive composite fine particles was 20 μm.

  The pressure-sensitive adhesive paper for ink jet obtained in the above Examples and Comparative Examples was evaluated by the following method, and the evaluation results are shown in Tables 1 and 2.

<Paint stability>
When the pressure-sensitive adhesive layer coating was prepared, the occurrence of aggregates was visually confirmed.
○: Aggregates are not generated.
Δ: Some aggregates are generated.
X: Aggregates are generated.

<Adhesive strength>
The obtained inkjet pressure-sensitive adhesive paper was left in an environment of 23 ° C. and 50% RH for 1 hour (without UV light irradiation treatment), and after being subjected to UV light irradiation treatment under the following conditions, at 23 ° C. and 50% RH environment. Two ink jet pressure bonding using a roller type press (Dupro, Mail Sealer MS6100, gap setting 22, roller spacing 170 μm (estimated value)) for one hour left (with UV light irradiation treatment) The pressure-sensitive adhesive layers of the paper were pressure bonded to each other. In addition, when the gap setting scale is set to 20 and 25 respectively in the press machine, the roller intervals are 150 μm and 200 μm, respectively, as the manufacturer's notarized values. From this, the roller interval in the gap setting 22 was estimated to be 170 μm.

(UV light irradiation conditions)
-Light source: Metal halide lamp (trade name: M03-L31,
Made by iGraphic, ozone generation type)
-Irradiation amount of UV light at an irradiation distance of 0 mm: 3.0 J / cm ²
・ Irradiation speed: 25 m / min ・ Irradiation distance: 100 mm

A T-type peel test was performed on the pressure-sensitive adhesive paper for ink jet immediately after pressure bonding under the conditions of a sample width of 25 mm and a pulling speed of 300 mm / min.
If the adhesive strength is 0.20 N / 25 mm or more, a pseudo-adhesive state is obtained. In particular, when the adhesive strength is 0.30 to 0.90 N / 25 mm, the peelability is good, which is preferable.

<Set off>
The obtained pressure-sensitive adhesive paper for ink jet is allowed to stand for 24 hours or more in an environment of 23 ° C. and 50% RH, and then applied to a pressure-sensitive adhesive layer with a commercially available dye ink jet printer (DCP-330C, black ink manufactured by Brother). Printing was performed. Then, using a roller type press (Duplo, mail sealer MS6100, gap setting 22, roller spacing 170 μm (the estimated value)) The pressure-sensitive adhesive layers were pressure bonded to each other. The state of occurrence of set-off (ink transfer to the unprinted pressure-sensitive adhesive layer side) upon peeling was visually confirmed.
○: Set-off does not occur.
Δ: Some set-off occurs.
X: Set-off is significant.

<Water resistance>
The obtained pressure-sensitive adhesive paper for ink jet is allowed to stand for 24 hours or more in an environment of 23 ° C. and 50% RH, and then a barcode pattern is printed with a commercially available dye ink jet printer (Brother DCP-330C, black ink). It was. Then, the bleeding state at the time of dripping water to a printing part was confirmed visually.
○: No bleeding occurs.
Δ: Slight bleeding occurs.
X: The bleeding is remarkable.

  From Tables 1 and 2, in each case, the pressure-sensitive adhesive layer coating material can be stably prepared, and a decrease in adhesive strength due to UV light irradiation is prevented. The pressure adhesive layer had sufficient adhesive strength and could be pseudo-adhered. Furthermore, the ink jet aptitude such as set-off and water resistance was excellent.

  In the case of Comparative Example 1 in which the pressure-sensitive adhesive layer does not contain the above-mentioned adhesive composite fine particles and an emulsion type adhesive (acrylic / vinyl acetate copolymer aqueous emulsion) is used, the cationic polymer is an acrylic / vinyl acetate copolymer. It aggregated with the combined aqueous emulsion, and the pressure-sensitive adhesive layer coating could not be stably prepared. Therefore, the adhesive strength of the pressure-sensitive adhesive layer is less than 0.20 N / 25 mm, which is a level at which pseudo-adhesion cannot be achieved. The adhesive strength of the pressure-sensitive adhesive layer after the UV light irradiation treatment was also less than 0.20 N / 25 mm, which was a level at which pseudo-adhesion was not possible.

  In the case of Comparative Example 2 in which pressure-sensitive adhesive composite fine particles were prepared using a natural rubber emulsion-type adhesive, the adhesive strength of the pressure-sensitive adhesive layer was 0.20 N / 25 mm or more before the UV light irradiation treatment. Although an adhesive state was obtained, the adhesive strength of the pressure-sensitive adhesive layer after the UV light irradiation treatment was less than 0.20 N / 25 mm, which was a level at which pseudo-adhesion was not possible.

Claims (5)

In the pressure-sensitive adhesive paper for inkjet that can be pseudo-adhered by providing a pressure-sensitive adhesive layer on at least one side of the base sheet,
After processing the pressure-sensitive adhesive layer surface with an irradiation distance of 100 mm using a light source with an irradiation distance (distance between the light source and the object to be irradiated) of 0 mm and a UV light irradiation amount of 3.0 J / cm ² Pressure-sensitive adhesive paper for ink jet adjusted to have an adhesive strength of 0.20 N / 25 mm or more.   The pressure-sensitive adhesive layer contains pressure-sensitive adhesive composite fine particles in a form in which fine particles of an emulsion-type adhesive are aggregated by a polyurea-polyurethane resin, silica, and a cationic polymer or a polyvalent metal salt. Item 1. A pressure-sensitive adhesive paper for inkjet according to Item 1.   The pressure-sensitive adhesive paper for inkjet according to claim 2, wherein the pressure-sensitive adhesive layer further contains a binder.   The pressure-sensitive adhesive composite fine particles are produced by adding 1 to 100 parts by mass (solid content) of a water-dispersible isocyanate compound to 100 parts by mass (solid content) of an emulsion type adhesive. The inkjet pressure-sensitive adhesive paper according to any one of 3.   The pressure-sensitive adhesive paper for ink jet according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer further contains a water-based acrylic resin emulsion containing acrylic acid ester and acrylonitrile as monomer components.