JP2008214594A - Pressure-sensitive adhesive sheet and method of manufacturing pressure-sensitive adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive sheet exhibiting superior pressure-sensitive adhesive performance in the temperature range of -10-50°C, also being superior in the punching aptitude from a pressure-sensitive adhesive sheet to a label, and a method of manufacturing the pressure-sensitive adhesive sheet. <P>SOLUTION: The pressure-sensitive adhesive sheet comprises a surface base material, a first pressure-sensitive adhesive layer formed on the rear surface side of the surface base material, an intermediate layer containing a pigment and a binder as main components formed on the first pressure-sensitive adhesive layer, and a second pressure-sensitive adhesive layer formed on the intermediate layer; and exhibits good balance between adhesive performance and label punching aptitude and remarkably suitable for use in seal printing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive sheet and a method for producing a pressure-sensitive adhesive sheet, and particularly relates to a pressure-sensitive adhesive sheet having excellent adhesion performance and label processing suitability in a temperature range of −10 to 50 ° C. and a method for producing a pressure-sensitive adhesive sheet.

  The pressure-sensitive adhesive sheet is used as a label, a seal, a sticker, a emblem, and the like for a wide range of uses such as commercial use, office use, and home use. In general, a pressure-sensitive adhesive sheet is constituted by laminating a surface substrate, a pressure-sensitive adhesive, and a release sheet (hereinafter, a laminate of a release agent, a barrier agent, and a release paper substrate is referred to as a release sheet in the present invention). is there. Paper, film, synthetic paper, metal foil, etc. are used for the surface substrate, and the release sheet is a release agent such as a silicone compound or fluorine compound for high density paper such as glassine paper, clay coat paper, polylamination paper, etc. The one coated with is used. Adhesives include solvent-type adhesives, emulsion-type adhesives, hot-melt-type adhesives, and the like. In recent years, emulsion-type adhesives have been frequently used from the viewpoint of disaster prevention and occupational health.

As a method for producing a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive coating solution is usually applied on a release sheet and dried, and then a surface base material is bonded onto the formed pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is bonded to the surface base material at the time of bonding. The method of transferring to is taken.
As the use of such adhesive sheets has diversified, the demand for adhesive performance has been diversified, and various types of adhesives are required for each application, but it can be classified according to the function of the adhesive used. It is roughly divided into permanent adhesion type and re-peeling type. The permanent adhesive type cannot be easily peeled off without destroying the surface substrate once it is applied. It is used for general-purpose types that are currently most commonly used and labels that are attached to food stored in the refrigerator. There are low-temperature adhesion types, and strong adhesion types that adhere firmly to adherends having rough surfaces such as sandpaper and tires. Further, the re-peeling type is a type that can be easily peeled without destroying the surface base material after achieving the purpose of display. In addition, there is a micro-adhesive type in which a microsphere-like pressure-sensitive adhesive layer is provided on the back surface of a memo paper, and sticking and peeling can be repeated many times.

By the way, the pressure-sensitive adhesives used for general-purpose pressure-sensitive adhesive sheets generally have high adhesive strength and holding power, but the current situation is that the adhesive strength is insufficient for low-temperature adherends of 5 ° C. or lower. is there. On the other hand, the pressure-sensitive adhesive used for the low-temperature pressure-sensitive adhesive sheet is naturally excellent in low-temperature adhesiveness, but has a drawback of low holding power, so when finishing a wound product with a slitter, the pressure-sensitive adhesive from the winding mirror surface Protrusion is likely to occur. For this reason, there exists a difficulty that an adhesive adheres to a slitter blade, or an adhesive adheres to a winding mirror surface, and is inferior to label processing aptitude. In addition, strong adhesive type adhesives are also excellent in rough surface adhesion, but due to the large amount of adhesive applied, there is a problem that the adhesive is likely to stick out, so it is difficult to label processing suitability as with the low temperature adhesive type. There is.
The re-peeling type adhesive or the slightly adhesive type adhesive has few difficulties in label processing suitability, but has insufficient adhesion to an adherend having a curved surface.
As described above, various pressure-sensitive adhesives have advantages and disadvantages in either adhesive performance or label processing suitability, and it is difficult to satisfy both performances with a single type of pressure-sensitive adhesive.

Therefore, Patent Document 1 proposes a pressure-sensitive adhesive sheet provided in a form in which a pressure-sensitive adhesive layer having a holding power of 8 hours or more and a pressure-sensitive adhesive layer having a holding power of 8 hours or less are sequentially laminated on one surface of a surface base material. However, there are disadvantages such as insufficient adhesive interlayer strength and easy interlaminar fracture. Patent Documents 2 and 3 disclose a technique for bonding an adhesive layer using a primer, but both of them have complicated manufacturing processes and are not energy efficient.
JP-A-2-286765 (Claims 1-2) JP-A-7-133467 (Claims 1 to 3) JP-A-8-309863 (Claim 1)

  An object of the present invention is to provide a pressure-sensitive adhesive sheet that exhibits excellent pressure-sensitive adhesive performance in a temperature range of −10 to 50 ° C. and excellent in punching process from a pressure-sensitive adhesive sheet to a label, and a method for producing the pressure-sensitive adhesive sheet. It is in.

  As a result of earnest research to solve the above problems, the present inventor formed a pressure-sensitive adhesive layer having a three-layer structure, and an intermediate layer mainly composed of a pigment and a binder between the two pressure-sensitive adhesive layers. It has been found that since the interlaminar strength of the entire pressure-sensitive adhesive layer is improved and the pressure-sensitive adhesive layer exhibits excellent adhesion performance at a low coating amount, occurrence of ouse is effectively suppressed. The present invention includes the following aspects.

The pressure-sensitive adhesive sheet of the present invention includes a surface base material, a first pressure-sensitive adhesive layer formed on the back side of the surface base material, and an intermediate mainly composed of a pigment and a binder formed on the first pressure-sensitive adhesive layer. A pressure-sensitive adhesive sheet comprising a layer and a second pressure-sensitive adhesive layer formed on the intermediate layer, and has a good balance between the adhesive performance of the pressure-sensitive adhesive sheet and the label processing suitability, and is extremely suitable for seal printing applications ing.
When the pigment of the intermediate layer is a kaolin pigment, it is possible to effectively suppress a decrease in adhesive strength after being stored for a long time as an adhesive sheet.
An acrylic polymer (A) in which the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer contains a functional group-containing (meth) acrylic acid alkyl ester copolymer (a) and a tackifying resin (b); A pressure-sensitive adhesive mainly composed of a mixture of a vinyl polymer (B) having a glass transition temperature of −50 ° C. to 50 ° C. is more preferable for suppressing the protrusion of the pressure-sensitive adhesive during label processing. .
The pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer is a non-ionic surfactant comprising a (meth) acrylic acid alkyl ester monomer made of polyoxyethylene alkyl ether, or from an anionic surfactant and polyoxyethylene alkyl ether. When the pressure-sensitive adhesive is mainly composed of an acrylic copolymer that is emulsion-copolymerized using a nonionic surfactant, the sensitivity does not decrease even when heat-sensitive recording paper is used as the surface substrate, and the pressure-sensitive adhesive sheet is long. There will be no decline in printing performance after storage for a period of time.
Three layers are applied simultaneously to the release sheet in the order of the second adhesive layer coating solution, the intermediate layer coating solution, and the first adhesive layer coating solution, and then dried and bonded to form a surface substrate. In the method for producing a pressure-sensitive adhesive sheet characterized by the above, the adhesion between the layers is improved, and the sticking-out of the pressure-sensitive adhesive is suppressed during label processing.
It is more preferable that the static surface tension of the coating liquid for the first and second pressure-sensitive adhesive layers is 20 to 40 mN / m in terms of suppressing foaming and stabilizing the curtain film when applied to the release sheet.
The static surface tension of the intermediate layer coating liquid is preferably 20 to 40 mN / m for the same reason as described above. When the adhesive layer coating solution and the intermediate layer coating solution are formed by the curtain coating method or the die coating method, a smooth coated surface can be obtained and the amount of the adhesive applied can be reduced, thereby preventing the adhesive from protruding. It is preferable because it is possible.

The pressure-sensitive adhesive sheet of the present invention is constituted by applying a second pressure-sensitive adhesive coating liquid, an intermediate layer coating liquid, and a first pressure-sensitive adhesive layer coating liquid to the release sheet in this order, and then drying and bonding the surface substrate. In addition, there is no occurrence of repellency or blurring of the coating liquid, and there is a good balance between the adhesive performance of the obtained pressure-sensitive adhesive sheet and the label processing suitability.
By using a kaolin pigment in the intermediate layer, it is possible to effectively suppress a decrease in adhesive strength after being stored for a long time as a pressure-sensitive adhesive sheet.
Acrylic polymer (A) and glass, wherein the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer contains a functional group-containing (meth) acrylic acid alkyl ester copolymer (a) and a tackifier resin (b) Since the main component is a mixture of a vinyl polymer (B) having a transition temperature of −50 ° C. to 50 ° C., it is possible to prevent the adhesive from protruding during label processing.
The pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer is made of (meth) acrylic acid alkyl ester monomer using a nonionic surfactant made of polyoxyethylene alkyl ether, or made of an anionic surfactant and polyoxyethylene alkyl ether. Since the main component is an acrylic copolymer that is emulsion-copolymerized with a nonionic surfactant, there is no decrease in sensitivity even when heat-sensitive recording paper is used as the surface substrate, and after storage for a long time as an adhesive sheet There will be no decline in printing performance.
Apply 3 layers simultaneously to the release sheet in the order of the second adhesive layer coating solution, the intermediate layer coating solution, and the first adhesive layer coating solution, then dry and paste the surface base material together to attach the adhesive sheet. By comprising, the adhesiveness between each layer improves and the protrusion of the adhesive at the time of label processing is suppressed.
By setting the static surface tension of the coating liquid for the first and second pressure-sensitive adhesive layers to 20 to 40 mN / m, it is possible to suppress foaming and stabilize the curtain film when applied to the release sheet.
For the same reason as above, the same effect can be obtained by setting the static surface tension of the intermediate layer coating liquid in the same range.
By applying curtain coating or die coating of the pressure-sensitive adhesive layer coating liquid and the intermediate layer coating liquid, a smooth coated surface can be obtained, and the amount of pressure-sensitive adhesive applied can be reduced, so that protrusion of the pressure-sensitive adhesive can be suppressed.

[Surface substrate]
The surface substrate used in the present invention is not particularly limited, and cast paper, coated paper, art paper, high-quality paper, synthetic paper, metal-deposited paper, cloth, nonwoven fabric, metal foil, various polymer films, etc. are used. it can. Further, a so-called thermal recording medium, thermal transfer recording medium, and ink jet recording medium, in which a recording layer is formed on those substrates, or recording properties such as thermal recording, ink jet recording, and thermal transfer recording are appropriately imparted by other methods may be used. it can. Incidentally, a so-called paper base such as cast paper, coated paper, art paper, and high-quality paper provided with a heat-sensitive recording layer is particularly referred to as a heat-sensitive recording paper among heat-sensitive recording media. Further, as the heat-sensitive recording paper, a system using a heat-sensitive paint containing a leuco dye and a colorant that causes the leuco dye to develop color when heated is more preferably used.

[Releasing paper base]
As release paper base paper used in the present invention, pulp mainly composed of wood fiber and recycled pulp is beaten appropriately with a required beating equipment, and an internal sizing agent, filler, fluorescent whitening agent, defoaming as necessary A pulp slurry is prepared by adding an auxiliary agent such as a solubilizer, and acidified with a sulfuric acid band or the like, so-called acidic paper-making base paper, or calcium carbonate or the like as a filler, and paper-making pH is weakly acidic to about 9.2. Thus, a base paper obtained by a so-called neutral papermaking can be used as appropriate. Here, examples of the paper machine include a long net multi-cylinder type paper machine, a long net Yankee type paper machine, and a circular net type paper machine. Examples of the base paper include high quality paper, medium quality paper, glossy paper, and craft. Paper and the like can be mentioned. Further, the surface of the base paper produced under the above conditions can be subjected to size press coating with oxidized starch, various surface sizing agents, and the like as necessary to improve the water absorption and paper strength.

[Release paper substrate and its barrier layer]
The release paper base paper obtained as described above is provided with a barrier agent layer to form a release paper substrate. The barrier agent layer mainly exhibits a function of suppressing the penetration of the silicone coating liquid used in the release agent layer. To do. Here, the type of the barrier agent layer is not particularly limited, but a pigment coat layer, polyvinyl alcohols, starches, polyethylenes and the like are appropriately selected. Among these, a styrene-butadiene copolymer latex having a pigment and a binder as main components and having a core / shell structure is preferable.

  The pigment used in the barrier agent layer is not particularly limited with respect to the type and blending ratio, and inorganic pigments such as kaolin, talc, calcium carbonate, titanium dioxide, aluminum hydroxide, and mica can be appropriately selected and used. . When the pigment is packed most closely, generally, the porosity of the plate-like pigment is lower than that of the spherical pigment, and a dense coating layer is formed. From this, it is preferable to use a plate-like pigment among the above pigments, and kaolin is particularly preferable. The blending amount of the pigment in the barrier agent layer is preferably 50 to 150 parts by mass, more preferably 80 to 120 parts by mass with respect to 100 parts by mass of the binder.

  The binder used in the barrier agent layer contains at least a styrene-butadiene copolymer latex having a core / shell structure. In the latex, the main component of the core part and the shell part is a copolymer latex containing styrene as a monomer unit. However, the composition of the copolymer latex (hereinafter referred to as “core component main component”) that is the main component of the core portion and the copolymer latex that is the main component of the shell portion (hereinafter referred to as “shell component main component”) is as follows. not the same. The core main component preferably contains butadiene as a monomer unit other than styrene. By including butadiene as a monomer unit, it is possible to obtain a latex having excellent adhesion to the release paper base paper. The copolymerization ratio (mass ratio) of butadiene in the core main component is preferably 30 to 170%, more preferably 60 to 140% with respect to styrene. If the copolymerization ratio of butadiene is too small, the effect of improving the adhesion to the release paper base paper due to the inclusion of butadiene units is difficult to obtain, and if it is too large, the recyclability of the release sheet may deteriorate. Examples of monomer units other than styrene and butadiene in the core main component include acrylic acid, methacrylic acid, and stearic acid. The copolymerization ratio (mass ratio) of monomer units other than styrene and butadiene in the core main component is preferably 0.1 to 20%, more preferably 0.1 to 5% with respect to styrene. . The ratio of the main component of the core part in the core part is preferably 80% by mass or more, and more preferably 95% by mass or more. Examples of the core component other than the core main component include acrylonitrile and methyl methacrylate. The glass transition temperature of the core (hereinafter abbreviated as Tg) is preferably −50 to −5 ° C., more preferably −30 to −3 ° C. By setting the Tg of the core part to be −50 ° C. or higher, good barrier properties can be obtained. Moreover, the effect of the adhesive improvement to release paper base paper can be acquired by setting it as -5 degrees C or less.

  The shell main component preferably contains acrylic acid as a monomer unit other than styrene. By including acrylic acid as a monomer unit, a latex excellent in blocking resistance and recyclability of the release sheet can be obtained. The copolymerization ratio (mass ratio) of acrylic acid in the shell main component is preferably 20 to 100%, more preferably 40 to 80% with respect to styrene. If the copolymerization ratio of acrylic acid is too small, it is difficult to sufficiently improve the blocking resistance and the recyclability of the release sheet due to the inclusion of acrylic acid units, and if it is too large, the adhesion to the release paper base may be too high. . Examples of monomer units other than styrene and acrylic acid in the shell main component include methacrylic acid and oleic acid. The copolymerization ratio (mass ratio) of monomer units other than styrene and acrylic acid in the shell main component is preferably 20% or less, more preferably 10% or less, relative to styrene. The ratio of the main component of the shell part in the shell part is preferably 80% by mass or more, and more preferably 90% by mass or more. Examples of the component of the shell portion other than the main component of the shell portion include polyurethane, polyethylene, polyvinyl chloride, polyvinyl acetate and the like. The Tg of the shell part is preferably -5 to 30 ° C, more preferably 5 to 25 ° C. By making the Tg of the shell part higher than −5 ° C., the stickiness of the barrier agent layer is reduced, and in particular, the blocking resistance of the release paper substrate can be improved. Moreover, favorable barrier property can be obtained by setting it as 30 degrees C or less.

  90 mass% or more is preferable and, as for the gel fraction with respect to the toluene of the whole latex which match | combined the core part and the shell part, 95 mass% or more is more preferable. When the gel fraction is 90% by mass or more, the stickiness of the barrier agent layer is reduced, and the blocking resistance and the recyclability of the release sheet are improved. Here, the “gel fraction” means the gel content (mass%) with respect to toluene (extraction treatment solvent), and is insoluble in toluene with respect to the total amount of resin (solid matter) when the latex resin (solid matter) is extracted with toluene. Means minutes.

  The mass ratio of the core part and the shell part (core part: shell part) is preferably 4:96 to 20:80, and more preferably 7:93 to 15:85. When the mass ratio of the core portion and the shell portion is in the above range, all of the adhesiveness, blocking resistance, and recyclability of the release sheet are good. Furthermore, the particle diameter of the copolymer latex used in the present invention is not particularly limited, but it is preferable to use a particle having a thickness of 100 to 400 nm because good adhesive strength to the release paper base paper can be obtained. .

  In the barrier agent layer, a binder other than the above-described core / shell type styrene-butadiene copolymer latex can be appropriately used in combination as long as the effects of the present invention are not impaired. For example, acrylic acid alkyl ester copolymer, styrene-acrylic acid alkyl ester copolymer, ethylene-vinyl acetate copolymer, vinyl acetate resin, hydrophobic resin emulsion such as wax, polyvinyl alcohol and derivatives thereof, starch and derivatives thereof , Cellulose derivatives, casein and the like. The ratio of the core-shell type styrene-butadiene copolymer latex in the total binder is preferably 50% or more, and more preferably 70% or more. In addition to the pigment and the binder, a dispersant, a water-proofing agent, a lubricant, an antifoaming agent, a preservative, a colorant, and the like can be appropriately added to the barrier agent layer of the present invention as necessary.

[Release paper substrate]
The release paper substrate can be produced by applying a barrier agent coating solution on at least one surface of a base paper and drying to form a barrier agent layer. The coating equipment for the barrier agent coating liquid is not particularly limited, and can be appropriately selected from a size press coater, a gate roll coater, a bar coater, a roll coater, an air knife coater, a blade coater, a rod blade coater and the like.
The coating amount of the barrier agent is not particularly limited, but in view of quality, price, etc., it is preferably 3-10 g / m ² in terms of absolute dry mass (solid content). In order to form a barrier agent layer, multilayer coating may be performed by two or more coating operations. Moreover, you may perform finishing processes, such as a super calendar, after application | coating as needed. By performing the finishing treatment, the smoothness of the surface of the barrier agent layer can be enhanced. As a result, a release agent coating solution (silicone or the like) can be applied uniformly.

[Peeling sheet and its release agent layer]
As the release sheet used in the present invention, a release agent layer is provided on the barrier agent layer surface of the release paper base as described above. The release agent layer is formed by applying a release agent coating solution to the surface of the barrier agent layer of the release paper substrate and curing it. As the release agent, for example, a silicone resin, a fluorine resin, a long chain alkyl resin, or the like is used, and among them, a silicone resin is preferably used.
As the silicone-based resin, solvent-diluted silicone diluted in an organic solvent such as toluene or hexane, solvent-free silicone having an effective solid content of 100% by mass, or the like is used. Among these, solventless silicone is preferably used from the viewpoint of environmental protection. Examples of the solventless silicone include thermosetting silicone compounds, electron beam curable silicone compounds, and ultraviolet curable silicone compounds. The method for applying these solvent-free silicones is not particularly limited, but generally a multistage roll coater, an offset gravure coater or the like is used. Coating amount 0.05~3.00g / ^{m 2} about this case, is preferably adjusted appropriately in a range of about 0.2 to 1.5 g / ^{m 2.} Incidentally, the amount of coating is poor to the effects of the release agent layer is less than 0.05 g / ^{m 2,} When it exceeds 3.00 g / ^{m 2,} poor necessity from economical viewpoint.

  The release sheet used has a clamping pressure of 1000 kPa according to ISO 8791-4 (1992) and a release sheet surface smoothness (hereinafter abbreviated as PPS) measured with a soft type backing disk of 2.0 to 3. It is preferably 5 μm. By doing so, a smooth pressure-sensitive adhesive layer surface can be obtained with a low pressure-sensitive adhesive application amount, and thus a pressure-sensitive adhesive sheet having excellent adhesive performance and suppressing occurrence of ouse can be obtained. The PPS range, also called dynamic smoothness, is defined as the smoothness of the release sheet that is suitable for carrying out the application of the adhesive coating liquid at a speed about twice that of the conventional method. It is presumed that smoothness was an important factor in applying a coating solution having a relatively low viscosity. Incidentally, when the smoothness is less than 2.0 μm, there is a possibility that repelling is likely to occur when the adhesive coating liquid is applied. When the smoothness exceeds 3.5 μm, it becomes difficult to obtain a smooth pressure-sensitive adhesive layer surface when the pressure-sensitive adhesive coating solution is applied, and there is a possibility that the adhesive force to various adherends may be reduced. As a more preferable range, the smoothness is 2.0 to 3.0 μm. Here, the smoothness was measured using Parker Print Surf (model: M596) manufactured by Messmer. The PPS on the surface of the release sheet was practically the same as the PPS on the surface of the barrier agent layer described above. This means that since the coating thickness of the release agent layer described above is at most about 1 μm, the smoothness at the stage where the barrier agent layer is formed is the same as the smoothness of the surface of the release sheet. Regarding the definition of repelling in the examples and the like in this specification, ○ means that there is no generation of repelling and that it is excellent in the applicability of the adhesive coating solution, and × is the problem of practical use as a pressure-sensitive adhesive sheet due to severe repelling. It means that it is a level.

Moreover, it is preferable that the contact angle with respect to the water of the release agent layer surface of the release sheet to be used is 60 to 75 °. Incidentally, when the contact angle is less than 60 °, the coating suitability is improved, but the peeling performance of the release sheet may be deteriorated. Conversely, if the contact angle exceeds 75 °, repellency may occur when the adhesive coating liquid is applied to the release sheet.
Here, the contact angle was measured 10 seconds after dropping using a contact angle measuring apparatus “Model CA-X” manufactured by Kyowa Interface Science Co., Ltd., with the amount of water dropped 1.8 μl.

  Examples of the silicone release agent that can provide such a contact angle include KNS330, KNS336, KNS3300 manufactured by Shin-Etsu Chemical Co., Ltd., Syl-Off SL100, SL160, SL200, SL300, SL8, SL9, SL10, SL30 manufactured by Toray Dow Corning. , SL40, Arakawa Chemical Industries, Ltd. manufactured by Silicone POLY360, 621V230, 11367, RCA396, XL323, and the like.

[Middle layer]
The intermediate layer used in the present invention is composed mainly of a pigment and a binder. Examples of pigments used there are heavy calcium carbonate, light calcium carbonate, kaolin, calcined kaolin, structural kaolin, delaminated kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, alumina, magnesium carbonate, magnesium oxide. , Silica, magnesium aluminosilicate, calcium silicate, white carbon, bentonite, zeolite, sericite, smectite and other mineral pigments, polystyrene resins, styrene-acrylic copolymer resins, urea resins, melamine resins, acrylic resins Organic pigments such as solid, hollow, or through-hole resins such as resins, vinylidene chloride resins, and benzoguanamine resins can also be used, and one or more of these can be selected as appropriate. Used. Of these, kaolin-based pigments such as kaolin, calcined kaolin, structural kaolin, and deramikaolin are preferred because they are most effective in reducing the adhesive strength when stored as an adhesive sheet for a long period of time.

  As the binder constituting the intermediate layer in the present invention, a water-soluble and / or water-dispersible polymer compound can be used. For example, cationic starch, amphoteric starch, oxidized starch, enzyme-modified starch, thermochemically-modified starch, Starch such as esterified starch, etherified starch, cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, natural or semi-synthetic polymer compounds such as gelatin, casein, xanthan gum, soybean protein, natural rubber, polyvinyl alcohols, polyisoprene, Polydienes such as polyneoprene and polybutadiene, polyalkenes such as polybutene, polyisobutylene, polypropylene and polyethylene, vinyl halide, vinyl acetate, styrene, (meth) acrylic acid, (meth) acrylic acid alkyl ester, (meth) acrylic Amide, (meth) acrylamide- (meth) acrylic acid copolymer, vinyl polymers such as methyl vinyl ether and copolymers, styrene-butadiene, methyl methacrylate-butadiene synthetic rubber latex, polyurethane resin, Examples thereof include synthetic polymer compounds such as polyester resins, polyamide resins, olefin-maleic anhydride resins, melamine resins, and the like. One or more selected from the above may be used according to the purpose. it can. Among them, from the viewpoint of binding power to pigments, cationic starch, amphoteric starch, oxidized starch, enzyme-modified starch, thermochemically modified starch, esterified starch, etherified starch and other starches, polyvinyl alcohol, styrene-butadiene, methyl Synthetic rubber latexes such as methacrylate-butadiene are preferred.

  In the present invention, the intermediate layer coating solution contains various auxiliary agents in addition to the pigments and binders, such as surfactants, pH adjusters, viscosity adjusters, water retention agents, softeners, gloss imparting agents, waxes, and dispersants. , Flow modifier, antistatic agent, stabilizer, antistatic agent, cross-linking agent, sizing agent, fluorescent brightener, colorant, ultraviolet absorber, antifoaming agent, water-resistant agent, plasticizer, preservative, fragrance Etc. can be appropriately selected and used within a range not impairing the desired effects of the present invention.

  The intermediate layer coating solution in the present invention is a solution in which a pigment, a binder, and other additives are dissolved or dispersed together, and the solid concentration of the coating solution is about 10 to 70% by mass. The blending ratio of the pigment and the binder is 5 to 100% by mass, preferably about 10 to 70% by mass with respect to the total solid content of the pigment.

  Moreover, it is preferable that the static surface tension of the intermediate layer coating solution measured by the Duneuling method or the Wilhelmy plate method is 20 to 40 mN / m. If the static surface tension is less than 20 mN / m, the liquid film may break frequently due to bubble breakage, and if the static surface tension exceeds 40 mN / m, repellency may easily occur.

The coating amount after drying of the intermediate layer of the present invention is 1 to 10 g / m ² , preferably ² to 8 g / m ² . Incidentally, if the coating amount is less than 1 g / m ² , the adhesiveness between the pressure-sensitive adhesive layer and the intermediate layer may be poor. Conversely, if it exceeds 10 g / m ² , the adhesive performance is excellent in label processing suitability. May decrease.

[Adhesive layer]
The first pressure-sensitive adhesive for the first pressure-sensitive adhesive layer, which is the main component of the first pressure-sensitive adhesive layer coating liquid used to form the first pressure-sensitive adhesive layer, hereinafter referred to as the first pressure-sensitive adhesive for short will be described. The first pressure-sensitive adhesive is not particularly limited, but basically illustrates a pressure-sensitive adhesive composed mainly of an acrylic polymer (A) and a vinyl polymer (B) having a Tg of −50 ° C. to 50 ° C. be able to. Here, the acrylic polymer (A) preferably comprises a functional group-containing (meth) acrylic acid alkyl ester copolymer (a) and a tackifier resin (b). By adopting such a configuration, it is possible to prevent the pressure-sensitive adhesive from protruding during the label processing. The functional group-containing (meth) acrylic acid alkyl ester copolymer (a) is a copolymer of a (meth) acrylic acid alkyl ester monomer, a monomer having a functional group, and another copolymerizable monomer. Specific examples of (meth) acrylic acid alkyl ester monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) acrylate. , Isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, n-nonyl (meth) acrylate , Isononyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, benzyl (meth) acrylate , Lauryl (meth) acrylate, cyclohexyl (meth) acrylate, tetradecyl (meth) acrylate, stearyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, ethyl carbitol (meth) acrylate. Although at least one kind can be used from these groups, it is particularly preferable to use a monomer selected from (meth) acrylic acid alkyl esters having an alkyl chain having 4 to 12 carbon atoms as a main component.

  It is preferable that the usage-amount of a (meth) acrylic-acid alkylester type monomer is 99.9 mass%-85.0 mass% with respect to the monomer whole quantity. When the usage-amount is less than 85.0 mass%, there exists a possibility that adhesive force may decline with respect to nonpolar adherends, such as a polyolefin-type film.

  Examples of the unsaturated monomer having a functional group include a carboxyl group, an amide group or a substituted amide group, an amino group or a substituted amino group, a hydroxyl group, an epoxy group, a carbonyl group, a mercapto group, or a silicon-containing group. Preferred are unsaturated monomers containing a carboxyl group, a hydroxyl group, a carbonyl group or an epoxy group. Specific examples of the carboxyl group-containing unsaturated monomer include (meth) acrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, and fumaric anhydride. Specific examples of the hydroxyl group-containing unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, caprolactone modified (meth) acrylate, polyethylene glycol (meta ) Acrylate, polypropylene glycol (meth) acrylate and the like. Specific examples of the carbonyl group-containing unsaturated monomer include acrolein, diacetone acrylamide, formyl styrene, vinyl methyl ketone, vinyl ethyl ketone, (meth) acrylooxyalkylpropenal, diacetone (meth) acrylate, and acetonyl (meth) ) Acrylate, acetoacetoxyethyl (meth) acrylate, and the like. Specific examples of the epoxy group-containing unsaturated monomer include glycidyl (meth) acrylate, glycidyl (meth) allyl ether, 3,4-epoxycyclohexyl (meth) acrylate, and the like. At least one selected from these functional group-containing unsaturated monomers can be used.

  The usage-amount of these functional group containing unsaturated monomers is 0.1 mass%-7.0 mass% with respect to the monomer whole quantity. When the amount used is less than 0.1% by mass, the mechanical stability is poor when blended with the vinyl polymer (B) or the like, and when a crosslinking agent is used, the effect is small. When the content is more than 7.0% by mass, the adhesive strength is reduced with respect to a non-polar adherend such as a polyolefin-based film, and is preferably 0.5% by mass to 4.0% by mass.

  Specific examples of other copolymerizable monomers include vinyl monomers such as vinyl acetate, vinyl propionate and vinyl versatate, divinylbenzene, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, ethylene glycol di ( (Meth) acrylate, 1,2-propylene glycol di (meth) acrylate, 1,3-propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) Examples thereof include monomers containing two or more polymerizable unsaturated groups such as acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, diallyl (meth) acrylate and the like. At least one or more of these groups can be used. The amount of other copolymerizable monomers used is 8.0% by mass or less based on the total amount of monomers. When it exceeds 8.0 mass%, adhesive force will decline with respect to nonpolar adherends, such as a polyolefin-type film.

  The functional group-containing (meth) acrylic acid alkyl ester copolymer (a) uses the above-described (meth) acrylic acid alkyl ester monomer, a monomer having a functional group and other copolymerizable monomers as monomer components. It can be obtained by an emulsion polymerization method in the presence of a surfactant in an aqueous medium.

  Although it does not specifically limit as surfactant to be used, Anionic surfactant, nonionic surfactant, and reactive surfactant can be used. Anionic surfactants include potassium oleate, sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium alkyl naphthalene sulfonate, sodium dialkyl sulfosuccinate, polyoxyethylene alkyl ether sodium sulfate, polyoxyethylene alkyl allyl ether sodium sulfate, Polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl allyl ether phosphate, etc. are mentioned. Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene oxypropylene block copolymers, polyethylene glycol fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and the like. Examples of reactive surfactants include polyethylene glycol mono (meth) acrylates having various molecular weights (different EO addition mole numbers), polyoxyethylene alkylphenol ether (meth) acrylates, ammonium 2- (meth) acryloyloxyethylsulfonate, Examples thereof include monomaleic acid ester of polyoxyethylene glycol and derivatives thereof, (meth) acryloyl polyoxyalkylene alkyl ether phosphate ester, and the like. Among the above, preferred are surfactants of higher alcohol derivatives among environmental hygiene, particularly environmental hormone problems.

  The amount of the surfactant to be used is usually about 0.1 to 10 parts by mass, preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the monomer component. When the amount of the surfactant used is within this range, an emulsion having an appropriate particle size can be obtained without producing a coagulated product, and the miscibility with the vinyl polymer (B) is improved. When there is too much surfactant, it exists in the tendency for adhesive force to decline with respect to nonpolar adherends, such as a polyolefin-type film.

  The acrylic polymer (A) is composed of the functional group-containing (meth) acrylic acid alkyl ester copolymer (a) and the tackifier resin (b). Examples of the tackifier resin (b) used include rosin resins, polyterpene resins, coumarone indene resins, phenol resins, xylene resins, aliphatic petroleum resins, aromatic petroleum resins, and the like. 1 or more can be used. Examples of the rosin resin include natural rosin, rosin ester, hydrogenated rosin, hydrogenated rosin ester, polymerized rosin, polymerized rosin ester, disproportionated rosin, and disproportionated rosin ester. Examples of the polyterpene resin include α-pinene resin, β-pinene resin, and terpene phenol resin. Further, there are hydrogenated petroleum resins such as aliphatic petroleum resins or aromatic petroleum resins. The usage-amount of tackifying resin (d) is 0.5-30 mass parts with respect to 100 mass parts of solid content of a functional group containing (meth) acrylic-acid alkylester type copolymer (c). When the amount used is less than 0.5 parts by mass, the adhesion to nonpolar adherends such as polyolefin films is reduced. When the amount used is more than 30 parts by mass, nonpolar covers such as polyolefin films at low temperatures are used. There is a risk that the adhesive strength to the body will be reduced. The tackifier resin (b) can be used as a composite resin emulsion with a resin by emulsion polymerization by coexisting the functional group-containing (meth) acrylic acid alkyl ester copolymer (a). Alternatively, a resin emulsion emulsified by a known method can be used after being added to the functional group-containing (meth) acrylic acid alkyl ester copolymer (a).

  The polymerization initiator that can be used for emulsion polymerization of the functional group-containing (meth) acrylic acid alkyl ester copolymer (a) is a generally used radical polymerization initiator. Radical polymerization initiators generate radicals by heat or reducing substances to cause addition polymerization of vinyl monomers, and include water-soluble or oil-soluble persulfates, peroxides, azobis compounds, etc. . Specifically, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl hydroxide, t-butyl peroxybenzoate, 2,2-azobisisobutyronitrile, 2,2-azobis (2 -Diaminopropane) hydrochloride, 2,2-azobis (2,4-dimethylvaleronitrile) and the like, preferably water-soluble. When acceleration of the polymerization rate or a low temperature reaction is desired, a reducing agent such as sodium bisulfite, ferrous chloride, ascorbic acid, formaldehyde sulfooxylate salt or the like can be used in combination with the radical polymerization initiator.

  Although the usage-amount of a polymerization initiator is 0.02-3 mass parts normally with respect to 100 mass parts of monomer components, Preferably it is 0.05-1 mass part.

  In the emulsion polymerization for obtaining the functional group-containing (meth) acrylic acid alkyl ester copolymer (a), the solid content is usually 30 to 75% by mass, preferably about 40 to 65% by mass in an aqueous medium. It can be carried out. The polymerization reaction is usually performed at a reaction temperature of about 40 to 95 ° C., preferably about 60 to 90 ° C. for 1 to 10 hours, preferably about 4 to 8 hours. As a monomer addition method, a batch addition method, a divided addition method, a continuous addition method, or the like, such as a monomer tap method or a monomer pre-emulsification tap method can be used. The monomer pre-emulsification tap method is preferred as a continuous addition method.

  The functional group-containing (meth) acrylic acid alkyl ester copolymer (a) obtained by the emulsion polymerization reaction has an average particle size of 0.2 to 1.0 μm. If the average particle diameter is within this range, the water dispersibility is good and the miscibility with the vinyl polymer (B) is also good. If the particle size is too small, the mechanical stability at the time of application tends to be poor, and if it is too large, unevenness of application such as streak tends to occur on the application surface. The average particle size of the functional group-containing (meth) acrylic acid alkyl ester copolymer (a) can be easily set by appropriately setting the type of surfactant and initiator, the amount added, the addition method, the stirring conditions, and the like. Can be adjusted.

  If necessary, a molecular weight modifier may be used for emulsion polymerization. Specific examples of the molecular weight modifier include butyl mercaptan, dodecyl mercaptan, octyl thioglycolate, isopropyl alcohol, methanol, carbon tetrachloride and the like. The usage-amount is 0.001-2.0 mass% with respect to a monomer component, Preferably it is 0.05-1.0 mass%.

  The vinyl polymer (B) is necessary for improving adhesion to nonpolar adherends such as polyolefin films, improving secondary processing suitability such as cutting, and imparting paper passing suitability in an electrophotographic system. The average particle diameter of the emulsion is preferably 0.05 to 0.6 μm, and Tg is preferably −50 to 50 ° C. When the average particle size is smaller than 0.05 μm, the mechanical stability of the vinyl polymer (B) emulsion is poor, and coarse particles are likely to occur when mixed with the acrylic polymer (A). When the average particle diameter is larger than 0.6 μm, the adhesive force to nonpolar adherends such as polyolefin-based films tends to decrease. When Tg is lower than −50 ° C., the adhesive strength of the pressure-sensitive adhesive blended with the acrylic polymer (A) to the nonpolar adherend such as polyolefin film is improved, but the suitability for secondary processing such as cutting is poor. There is a risk. When Tg exceeds 50 ° C., the suitability for secondary processing such as cutting is improved, but the adhesion to nonpolar adherends such as polyolefin-based films, particularly adhesion from room temperature to low temperature may be deteriorated. . Here, the average particle diameter of the emulsion is a value measured by, for example, a Nikon model 370 (manufactured by Particle Sizing System Kogyo Co., Ltd.) using a light scattering particle size distribution measuring machine. The Tg of the vinyl polymer (B) is calculated using the Tg value of each homopolymer described in the Japan Emulsion Industry Association Standard “Method of Displaying the Film Hardness of Synthetic Resin Emulsion (107-1996)” (Fox It is a value obtained from the formula.

  The usage-amount of a vinyl type polymer (B) is 0.5-20 mass parts by solid content with respect to 100 mass parts of solid content of an acrylic polymer (A). When the amount used is less than 0.5 parts by mass, there are few effects on secondary processing suitability such as adhesion to nonpolar adherends such as polyolefin-based films and cutting. When it exceeds 20 mass parts, the adhesive force in the low temperature area | region with respect to nonpolar adherends, such as a polyolefin-type film, will fall. When the vinyl polymer (B) is used in combination with a tackifier resin, the adhesiveness to nonpolar adherends such as polyolefin films and the suitability for secondary processing such as cutting are further improved.

  The vinyl polymer (B) has a monomer component (hereinafter also referred to as “hard monomer”) having a high homopolymer Tg of 70 to 110 ° C., and a monomer component having a low homopolymer Tg of −100 to −10 ° C. Hereinafter, it is also referred to as “soft monomer”) and a monomer mixture comprising a functional group-containing unsaturated monomer. Specific examples of the hard monomer having a homopolymer Tg of 70 to 110 ° C. include styrene, methyl methacrylate, cyclohexyl methacrylate, vinyl benzoate, acrylonitrile, t-butyl methacrylate, and preferably styrene and methyl methacrylate. is there. Specific examples of the soft monomer having a homopolymer Tg of −100 to −10 ° C. include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, and 2-ethylhexyl. Examples include acrylate, octyl acrylate, n-nonyl acrylate, isononyl acrylate, 2-methoxyethyl acrylate, and ethyl carbitol acrylate. One or more of these groups can be used.

  The vinyl polymer (B) has a monomer component of 100% by mass, for example, 25.0-85.0% by mass of a hard monomer having a Tg of 70-110 ° C., so that the Tg is −50 to 50 ° C. At least one functional group selected from 14.5 to 70% by mass of a soft monomer having a Tg of −100 to −10 ° C., a carboxyl group-containing unsaturated monomer, a carbonyl group-containing unsaturated monomer, and a hydroxyl group-containing unsaturated monomer It can be obtained by an ordinary known emulsion polymerization method in the presence of a surfactant in an aqueous medium using 0.5 to 5.0% by mass of the contained unsaturated monomer as a monomer component.

  A crosslinking agent may be added to the first pressure-sensitive adhesive to further increase the holding power. As a crosslinking agent that can be used, a glycidyl compound having at least two glycidyl groups in one molecule, an aziridine compound having at least two aziridine groups in one molecule, an oxazoline compound having an oxazoline group in one molecule, one molecule A hydrazide compound or a polyvalent metal complex having at least two hydrazide groups can be used. The acrylic polymer (A) and the vinyl polymer (B) can be appropriately selected depending on the type of functional group used.

  Specific examples of the glycidyl compound having at least two or more glycidyl groups in one molecule include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and neopentyl glycol diester. Glycidyl ether, 1,6-hexanediol diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, o-phthalic acid diglycidyl ether, glycerin polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol poly Examples thereof include glycidyl ether and sorbitol polyglycidyl ether. The amount of the epoxy group introduced by the glycidyl compound is from 0.01 to 1 equivalent to 1 equivalent of carboxyl groups or hydroxyl groups constituting the polymer particles of the acrylic polymer (A) and the vinyl polymer (B). 2 equivalents. When the amount used is less than 0.01 equivalent, the suitability for secondary processing such as cutting is poor, and adhesion of the adhesive to the electrophotographic photosensitive drum or the fixing roll tends to occur. When it exceeds 2 equivalents, the cohesive force becomes too high, and the adhesive force to nonpolar adherends such as polyolefin-based films may be reduced.

  Specific examples of the aziridine compound having at least two aziridine groups in one molecule include 1,1 ′-(methylene-di-p-phenylene) bis-3,3-aziridinylurea, 1,1′-. (Hexamethylene) bis-3,3-aziridinylurea, ethylenebis- (2-aziridinylpropionate), tris (1-aziridinyl) phosphine oxide, 2,4,6-triaziridinyl-1,3,5- And triazine, trimethylolpropane-tris- (2-aziridinylpropionate), and the like. The amount used is 0.01 to 2 equivalents relative to 1 equivalent of the carboxyl group in which the aziridine group introduced by the aziridine compound constitutes the polymer particles of the acrylic polymer (A) and the vinyl polymer (B). It is. If the amount used is less than 0.01 equivalent, the suitability for secondary processing such as cutting is poor, and if it exceeds 2 equivalents, the cohesive force becomes too high, and the adhesion to nonpolar adherends such as polyolefin films is high. May decrease.

  As a compound containing an oxazoline group in one molecule, any compound having an oxazoline group in the molecule and an aqueous dispersion or a water-soluble crosslinking agent can be used without any limitation. For example, as described in JP-B-7-68499, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2 One or more addition-polymerizable oxazolines such as 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the above (meta ) A water-based crosslinking agent obtained by copolymerization using an alkyl acrylate monomer is used. Specifically, trade names “Epocross K-1010E”, “Epocross K-1020E”, “Epocross K-1030E”, “Epocross K-2010E”, “Epocross K-2020E”, “Epocross” manufactured by Nippon Shokubai Co., Ltd. K-2030E "," Epocross WS-500 "," Epocross WS-700 "can be used. The amount of the water-based cross-linking agent containing the oxazoline group is 0. 0 with respect to 1 equivalent of the carboxyl group in which the introduced oxazoline group constitutes the polymer particles of the acrylic polymer (A) and the vinyl polymer (B). 01 to 2 equivalents. When the amount used is less than 0.01 equivalent, the suitability for secondary processing such as cutting is deteriorated, and adhesion of the adhesive to the electrophotographic photosensitive drum and the fixing roll is likely to occur. When it exceeds 2 equivalents, the cohesive force becomes too high, and the adhesive force to nonpolar adherends such as polyolefin-based films may be reduced.

  Specific examples of hydrazide compounds having at least two hydrazide groups in one molecule include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutamic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumarate Examples include acid dihydrazide, itaconic acid dihydrazide, ethylene-1,2-dihydrazide, propylene-1,3-dihydrazide, butylene-1,4-dihydrazide. The hydrazide group introduced by the hydrazide compound is used in an amount of 0.01 to 2 equivalents relative to 1 equivalent of the carbonyl group constituting the polymer particles of the acrylic polymer (A) and the vinyl polymer (B). It is. When the amount used is less than 0.01 equivalent, the suitability for secondary processing such as cutting is poor, and adhesion of the adhesive to the electrophotographic photosensitive drum or the fixing roll tends to occur. When it exceeds 2 equivalents, the cohesive force becomes too high, and the adhesive force to nonpolar adherends such as polyolefin-based films may be reduced.

  The polyvalent metal complex salt can be used as an aqueous solution or an aqueous dispersion thereof. After coating and drying, a metal compound having a valence of 2 or more that can be metal-crosslinked with a carboxyl group in the acrylic polymer (A) or the vinyl copolymer (B) is selected. Examples thereof include inorganic acid salts and organic acid salts such as calcium, magnesium, zinc, aluminum, zirconium, and titanium. These metal salts are preferably used as ammonium complexes of metal salts containing ammonia. In particular, ammonium complexes of carbonates selected from zinc and zirconium are more effective in terms of stability of the compounding solution and increase in cohesive strength after metal cross-linking. Zircoammonium carbonate, ammonium ammonium carbonate, ammonium complex of zinc acetate Etc. can be used. The amount used is preferably 0.01 to 1 equivalent with respect to the carboxyl group in the acrylic polymer (A). When the amount is less than 0.01 equivalent, suitability for secondary processing such as cutting is deteriorated. If it exceeds 1 equivalent, the cohesive force becomes too high, and the adhesive force to nonpolar adherends such as polyolefin films may be reduced.

  In addition to the first adhesive, the first adhesive layer coating liquid is a known plasticizer, filler, pigment, thickener, viscosity modifier, wetting agent as an additive for the adhesive layer coating liquid. , Leveling agents, antifoaming agents, preservatives, dispersants, antioxidants, antifreezing agents, flame retardants, and the like may be included as long as the effects of the present invention are not impaired.

  As the plasticizer, hydrocarbon (process oil, liquid polybutadiene, liquid polyisobutylene, liquid polyisoprene, liquid paraffin, chlorinated paraffin, paraffin wax, copolymer oligomer of ethylene and α-olefin (C3-20) (mass ratio 99) 0.9 / 0.1 to 0.1 / 99.9, Mw 5,000 to 100,000)), and a copolymer oligomer of α-olefin (C4 to 20) excluding propylene and ethylene (mass ratio 99.9 / 0.1 to 0.1 / 99.9, Mw 5,000 to 100,000)), ester (phthalic acid ester (diethyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, didecyl phthalate, dilauryl phthalate), Distearyl phthalate, diisononyl phthalate, etc.)), adipic acid ester ( Di (2-ethylhexyl) adipate, dioctyl adipate, etc.), sebacic acid esters (dioctyl sebacate, etc.), animal and vegetable oils (linoleic acid, linolenic acid, etc.), and hydrogenated unsaturated double bonds thereof A hydrogenated product of the product.

  Fillers include carbonates (magnesium carbonate, calcium carbonate, etc.), sulfates (aluminum sulfate, calcium sulfate, barium sulfate, etc.), sulfites (calcium sulfite, etc.), molybdenum disulfide, silicates (aluminum silicate, calcium silicate) Etc.), diatomaceous earth, silica stone powder, talc, silica, zeolite and the like.

  Examples of pigments include inorganic pigments (alumina white, graphite, titanium oxide, ultrafine titanium oxide, zinc white, black iron oxide, mica-like iron oxide, lead white, white carbon, molybdenum white, carbon black, resurge, lithopone, barite, Cadmium red, Cadmium mercury red, Bengala, Molybdenum red, Red lead, Yellow lead, Cadmium yellow, Barium yellow, Strontium yellow, Titanium yellow, Titanium black, Chrome oxide green, Cobalt oxide, Cobalt green, Cobalt chromium green, Ultramarine blue, Bitumen, cobalt blue, cerulean blue, manganese purple, cobalt purple, etc.) and organic pigments (shellac, insoluble azo pigments, soluble azo pigments, condensed azo pigments, phthalocyanine blue, dye lakes, etc.).

  Antioxidants include hindered phenol compounds (triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] etc.) and phosphorous acid Ester compounds [tris (2,4-di-t-butylphenyl) phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, bis (2,6-di-t- Butylphenyl) pentaerythritol-di-phosphite, tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenylene Di - phosphonite, etc.] and the like.

Examples of the antifreezing agent include propylene glycol.
Examples of the thickener include carboxyvinyl polymer, carboxymethylcellulose, gelatin, dextrin, hydroxypropylmethylcellulose, hydroxypropylcellulose, alginic acid (salt) and the like.

  As the viscosity modifier, a water-soluble polymer is usually used. Specific examples thereof include polyvinyl pyrrolidone, polyvinyl alcohol, hydroxyethyl cellulose, methoxypropyl cellulose, polyacrylamide, polyacrylic acid, polymethacrylic acid, or among these. The mixture of 2 or more types is mentioned.

  Wetting agents include higher alcohol sulfates and their salts, alkylbenzene sulfonates, polyoxyethylene alkylphenyl sulfonates, polyoxyethylene alkyl diphenyl ether sulfonates, alkyl diphenyl ether disulfonates, succinic acid dialkyl ester sulfonates. Nonionic interfaces such as anionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene diphenyl ether, polyoxyethylene-polyoxypropylene block copolymer, acetylenic diol surfactant An activator is mentioned.

  The leveling agent is not particularly limited, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and zwitterionic surfactants, and more specifically, anionic surfactants. Examples of the activator include sulfates of higher alcohols and salts thereof, alkylbenzene sulfonates, polyoxyethylene alkylphenyl sulfonates, polyoxyethylene alkyl diphenyl ether sulfonates, alkyl diphenyl ether disulfonates, dialkyl ester sulfones of succinic acid. Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene diphenyl ether, polyoxyethylene-polyoxypropylene. A block copolymer, an acetylenic diol surfactant, and the like, and examples of the cationic surfactant include alkyl (amido) betaine, alkyldimethylamine oxide, and the like, one or more of these. Can be used.

In addition to the above surfactants, fluorine-based surfactants and silicone-based surfactants can also be used as special surfactants.
There is no restriction | limiting in particular as a dispersing agent, It can select suitably from well-known things conventionally known as surfactant.
Specifically, sodium alkylbenzene sulfonate, sodium alkyldiphenyl ether disulfonate, sodium lauryl sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium alkyl naphthalene sulfonate, fatty acid sodium, sodium dodecylbenzene sulfonate, disodium alkylene disulfonate, dialkyl Sodium sulfosuccinate, sodium monoalkylsulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl ether phosphate, sodium polyoxyalkylene alkyl ether phosphate, calcium lignin sulfonate, sodium melamine resin sulfonate, etc. Anionic surfactant, polyoxyethylene Octylphenyl ether, polyoxyethylene nonylphenol ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, Nonionic surfactants such as polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, and polyoxyethyleneoxypropylene block copolymers are listed. In addition, polyacrylic acid and its metal salt, gluconate, olefin-maleate copolymer, carboxymethylcellulose and its metal salt, metal soap, stearic acid triethanolamine, hydroxyethylcellulose, polyvinylpyrrolidone, methylcellulose, hexametaphosphate, magnesium Aluminum silicate, sodium / magnesium silicate, polyoxyethylene oleyl ether, funnel oil, casein, polyamide and the like can also be used.

  Examples of the antifoaming agent include polysiloxane compounds containing hydrophobic silica and mineral oil.

  Examples of the preservative include formalin, salicylic acid, methyl paraben, ethyl paraben, propyl paraben, butyl paraben, imidazolidinyl urea, phenoxyethanol, isothiazolinone, diazolidinyl urea, quaternium and the like.

  Flame retardants include halogen flame retardants, metal hydroxide flame retardants, melamine cyanurate, triazine compounds, guanidine compounds, guanyl urea compounds, nitrogen-containing compounds such as melamine / formaldehyde resins, ammonium polyphosphate, melamine polyphosphate, etc. Is mentioned.

  The pressure-sensitive adhesive for the second pressure-sensitive adhesive layer, which will be the main component of the second pressure-sensitive adhesive layer coating solution used for forming the second pressure-sensitive adhesive layer, will be hereinafter referred to as the second pressure-sensitive adhesive for short. Although it will not specifically limit if a 2nd adhesive has the physical property different from a 1st adhesive, for example, Tg etc., In order to have the adhesive performance outstanding from -10 degreeC, the adhesive of the following aspect is preferable.

  That is, the second pressure-sensitive adhesive uses a (meth) acrylic acid alkyl ester monomer as a nonionic surfactant composed of polyoxyethylene alkyl ether, or a nonionic surfactant composed of an anionic surfactant and polyoxyethylene alkyl ether. The main component is an acrylic copolymer that has been emulsion-copolymerized with an agent, so that there is no reduction in sensitivity even when using thermal recording paper as the surface substrate, and the printing performance after being stored for a long time as an adhesive sheet. A decrease is not recognized. That is, the color former in the heat-sensitive recording layer moves to the pressure-sensitive adhesive layer, and the phenomenon that the color density decreases is less likely to occur.

  Here, examples of the nonionic surfactant constituting the second pressure-sensitive adhesive include polyoxyethylene alkylphenyl ethers such as polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether, polyoxyethylene lauryl ether, and polyoxyethylene. Examples include stearyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether, polyoxypolycyclic phenyl ethers such as polyoxyethylene distyrenated phenyl ether, polyoxyethylene sorbitan fatty acid esters, etc., but environmental problems (endocrine From the viewpoint of disturbing substances, polyoxyethylene alkyl ethers containing no alkylphenol group are preferred.

  Examples of the anionic surfactant constituting the second pressure-sensitive adhesive include fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, and alkyl phosphates. Salt, alkylallyl sulfate ester salt, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl sulfate ester salt, polyoxyethylene alkyl phenyl ether sulfate ester salt, polyoxyethylene alkyl allyl sulfate ester salt, polyoxyethylene alkyl phosphate ester salt And special polycarboxylic acid type polymer surfactants. Among these, among the anionic surfactants, fatty acid salts that do not contain a polyoxyethylene moiety, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, More preferably, it is at least one selected from alkyl phosphates, alkylallyl sulfate esters, and naphthalenesulfonic acid formalin condensates.

  Further, a reactive surfactant having a carbon-carbon double bond described in JP-A-7-82537 can be used in combination.

The second pressure-sensitive adhesive is polymerized as follows using a nonionic surfactant or a combination of a nonionic surfactant and an anionic surfactant.
A polymer having at least one ester group-containing monomer selected from the group of (meth) acrylic acid alkyl esters as a main component is polymerized. The Tg of this polymer is preferably −60 to −40 ° C. When the Tg of the second pressure-sensitive adhesive layer is less than −60 ° C., the low-temperature suitability is good, but the pressure-sensitive adhesive may protrude in the printing / labeling process. Conversely, if the Tg of the second pressure-sensitive adhesive layer exceeds −40 ° C., the low-temperature suitability may be inferior. And the 1st adhesive and 2nd adhesive which comprise an adhesive layer contain a (meth) acrylic-acid alkylester copolymer as a main component, Tg of a 1st adhesive layer> 2nd adhesive layer Tg is preferred.
The above-mentioned polymer is produced by a known emulsion polymerization method. As a monomer addition method, a batch addition method, a division addition method, a continuous addition method, etc., a monomer tap method, a monomer pre-emulsion tap method, etc. It can be carried out. The monomer pre-emulsification tap method is preferred as a continuous addition method.

  The average particle size of the above polymer is 0.1 to 0.5 μm, preferably 0.15 to 0.35 μm. If the average particle size is less than 0.1 μm, an emulsion having a high viscosity and inferior coating properties is produced, and if it is greater than 0.5 μm, the adhesion performance of the produced copolymer cannot be sufficiently improved.

Examples of the polymer include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and isobutyl (meth) acrylate. , (Meth) acrylic acid-t-butyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid-2-ethylhexyl, (meth) acrylic acid isononyl, (meth) acrylic acid lauryl, (meth) acrylic acid stearyl At least one selected from the group consisting of vinyl acetate, styrene, ethylene, vinyl chloride, vinylidene chloride, ethylenically unsaturated carboxylic acid, crosslinkable monomer, α-methylstyrene, N-alkyl (meth) acrylamide, (meth) Less copolymerizable monomers selected from acrylonitrile Copolymer also comprising one are preferred. Examples of the ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, monoalkyl malate having 1 to 12 carbon atoms in the alkyl group, hydroxy monomaleate, hydroxypropyl Examples thereof include monomalate, phthalic acid, and monoalkyl (carbon number 1 to 12) ester of itaconic acid. Examples of the crosslinkable monomer include (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, (meth) acrylic acid-3-hydroxyethyl, polyethylene glycol or polypropylene glycol mono ( Hydroxyl group-containing monomers such as (meth) acrylate, epoxy group-containing monomers such as glycidyl (meth) acrylate, monomers having -CONH ₂ groups and methylol groups such as (meth) acrylamide and diacetone acrylamide, divinylbenzene, divinylsilane, diallyl Mention may be made of monomers having two or more ethylenically unsaturated bonds such as phthalate, cyclopentadiene, methylenebisacrylamide, diallylmalate, tetraallyloxyethane.

  In addition to the second pressure-sensitive adhesive, the second pressure-sensitive adhesive layer coating liquid is also known as a film-forming auxiliary, plasticizer, filler, pigment, thickener, viscosity, as an additive for the pressure-sensitive adhesive layer coating liquid. An adjusting agent, a wetting agent, an antifoaming agent, a preservative, a dispersing agent, an antioxidant, an antifreezing agent, a flameproofing agent, a flame retardant, and the like may be included as long as the effects of the present invention are not impaired. The additive for the pressure-sensitive adhesive layer coating solution can be the same as the additive used in the first pressure-sensitive adhesive layer coating solution, and therefore the description thereof is omitted.

Furthermore, the tensile strength (measured by a method according to JIS-K-6301 (1995)) of the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer is 5.0 to 15.0 kg / cm ² , and the elongation (JIS-K- 6301 (measured by a method according to 1995)) is preferably 800 to 1,200%. If the tensile strength is less than 5.0 kg / cm ² , the holding power is lowered, and the sticking out of the adhesive during label processing may be deteriorated. If the tensile strength exceeds 15.0 kg / cm ² , the adhesive strength to non-polar polyolefin adherends may be reduced. Moreover, there exists a possibility that the adhesive force with respect to a nonpolar polyolefin-type to-be-adhered body may fall that elongation rate is less than 800%. If the elongation exceeds 1,200%, the holding power is reduced, and the sticking out of the adhesive during label processing may be deteriorated. Furthermore, it is preferable that the gel fraction with respect to tetrahydrofuran of the adhesive which comprises a 2nd adhesive layer is 30-80 mass%. When the gel fraction is less than 30% by mass, the holding power is lowered, and the sticking out of the pressure-sensitive adhesive during label processing may be deteriorated. On the other hand, if the gel fraction exceeds 80% by mass, the adhesion to non-polar polyolefin adherends may be reduced.

  Here, although the physical property of the coating liquid for 1st and 2nd adhesive layers is demonstrated, it is not necessarily limited to this. The static surface tension of the first and second pressure-sensitive adhesive layer coating liquids is preferably 20 to 40 mN / m. If the static surface tension of the pressure-sensitive adhesive layer coating liquid is less than 20 mN / m, the coating liquid tends to foam and a uniform dry coating film may not be obtained. On the other hand, if the static surface tension of the pressure-sensitive adhesive layer coating liquid exceeds 40 mN / m, the curtain film may not be uniformly formed when the curtain is applied.

As for the method of constituting the pressure-sensitive adhesive sheet, the second pressure-sensitive adhesive coating liquid, the intermediate layer coating liquid, and the first pressure-sensitive adhesive coating liquid are applied almost simultaneously in this order on the surface of the release agent layer of the release sheet, and then dried. Is formed, and the surface base material is bonded together to adjust the humidity and the like to be finished into an adhesive sheet.
Examples of the coating method for forming the pressure-sensitive adhesive layer include devices such as a reverse roll coater, a knife coater, an air knife coater, a die coater, a curtain coater, a reverse gravure coater, and a vario gravure coater. It is preferable to use a slide die coater or a slide curtain coater in order to simultaneously coat the agent layer and the intermediate layer. In particular, when a slide curtain coater is used, it is difficult for the above-mentioned other coaters to generate a living line that is likely to occur on the pressure-sensitive adhesive coating surface. Even if the pressure-sensitive adhesive sheet is formed using a release sheet having a relatively low smoothness, It was found that a pressure-sensitive adhesive layer surface excellent in temperature was obtained, and excellent adhesive performance was exhibited even at a low coating amount. Furthermore, since the amount of application is low, the occurrence of ouse can be effectively suppressed, and the workability of label processing with a printing press is excellent. The coating amount of the pressure-sensitive adhesive layer is 8 to 30 g / m ² , preferably 10 to 27 g / m ² . The coating speed is preferably 400 to 800 m / min. Incidentally, when the coating speed is less than 400 m / min, it takes too much time to reach the drying zone after applying the pressure-sensitive adhesive coating solution, and there is a possibility that repelling may occur on the release sheet. On the other hand, when the coating speed exceeds 800 m / min, a shear rate of about 4.5 × 10 ⁵ (s ⁻¹ ) or more is obtained, and the viscosity of the pressure-sensitive adhesive coating liquid may be reduced to cause repellency.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In the examples, “parts” and “%” are parts by mass and mass% (solid content) unless otherwise specified.

(Manufacture of thermal recording paper as surface substrate)
[Manufacture of thermal recording paper base paper]
Kaolin is added to a pulp slurry containing 25 parts of NBKP (C.S.F. 550 ml) and 75 parts of LBKP (C.S.F. 560 ml) so that the paper ash content is 5.0%. As a sizing agent, a rosin size was added to 1.5% of the absolutely dry pulp and 2.0% of aluminum sulfate was added to obtain a paper stock. This stock was made with a long mesh multi-cylinder cylinder dryer paper machine and processed with a 4-stage super calender to obtain a 58 g / m ² base paper. The sizing degree of the 20% ethyl alcohol aqueous solution of this base paper was 10 seconds.

[Manufacture of thermal recording paper]
(Preparation of solution A)
A composition comprising 10 parts of 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-phenylaminofluorane, 5 parts of 5% methylcellulose aqueous solution, and 40 parts of water was adjusted to an average particle size of 3 μm with a sand mill. It grind | pulverized until it became.

(Liquid B preparation)
A composition comprising 30 parts of 4-hydroxy-4′-isopropyloxydiphenylsulfone, 5 parts of 5% methylcellulose aqueous solution, and 80 parts of water was pulverized with a sand mill until the average particle size became 3 μm.

(C liquid preparation)
A composition comprising 20 parts of 1,2-di (3-methylphenoxy) ethane, 5 parts of a 5% aqueous solution of methylcellulose, and 55 parts of water was pulverized with a sand mill until the average particle size became 3 μm.

(Preparation of solution D)
A composition comprising 200 parts of a 10% acetoacetyl group-modified polyvinyl alcohol aqueous solution, 100 parts of kaolin (trade name: UW-90, manufactured by EMC), 30 parts of a 30% zinc stearate dispersion, and 100 parts of water is mixed and stirred. A coating solution was obtained.

It is obtained by mixing and stirring 55 parts of A liquid, 115 parts of B liquid, 80 parts of C liquid, 80 parts of 10% polyvinyl alcohol aqueous solution, and 35 parts of calcium carbonate on the surface of the base paper of the thermal recording paper obtained previously. The coating liquid was applied and dried so that the coating amount after drying was 6 g / m ² to form a heat-sensitive recording layer. On this heat-sensitive recording layer, the liquid D was applied and dried so that the coating amount after drying was 5 g / m ^2, and then calendered to obtain a heat-sensitive recording paper.

(Example 1)
[Barrier coating solution]
The following composition as the binder in the barrier agent layer (monomer unit and its mass ratio, Tg)
Core part (styrene: butadiene = 5: 5, Tg: −19 ° C.)
Shell part (styrene: acrylic acid: oleic acid = 54: 34: 2, Tg: 26 ° C.)
A composite latex having a core / shell structure (trade name “A6160”, gel fraction: 96%, Tg of the composite latex as a whole: 21 ° C., manufactured by Asahi Kasei Corporation) was used.
A plate-like kaolin was used as a pigment, and a barrier agent coating solution having a concentration of 50% by mass was prepared so that styrene-based copolymer latex: plate-like kaolin = 1: 1 (mass ratio).
[Manufacture of release paper substrate]
On one side of fine paper (basis weight 78 g / m ^2), the barrier coating solution a 7 g / m ² was coated with bone dry weight (solid content) and dried to smoothed by calendering. In addition, curl control was performed with backside steam humidification (steam box) to obtain a release paper substrate.
[Release coating liquid]
Arakawa Chemical Industries, Ltd. solvent-free silicone release agent "POLY360 (base polymer)" 28 parts by mass, "621V230 (base polymer)" 50 parts by mass, "11367 (base polymer)" 18 parts by mass, "XL323 (crosslinking agent)" “3.7 parts by mass and 4 parts by mass of“ catalyst ”were mixed to prepare a release agent coating solution.
[Manufacture of release sheet]
The above-mentioned solvent-free silicone release agent was applied to the release paper base surface of the release paper substrate with a multi-stage roll coater so as to be 1.1 g / m ² and then cured with hot air to obtain a release sheet.

[Manufacture of intermediate layer coating solution]
Add 90 parts by weight of kaolin (trade name: “Miragros 91”, manufactured by Engelhard) and 0.1 parts by weight of water and a dispersant (trade name: “Aron A-9”, manufactured by Toagosei Co., Ltd.) The kaolin dispersion liquid having a solid content of 72% by mass was obtained. A pigment slurry was prepared by adding 10 parts by mass of a heavy calcium carbonate dispersion liquid (trade name: “FMT-97”, manufactured by Phima Tech Co., Ltd.) having a solid content of 75% by mass to this dispersion. 4 parts by mass of oxidized starch (trade name: “Ace B”, manufactured by Oji Cornstarch Co., Ltd.), styrene-butadiene copolymer latex (trade name: “0619”, manufactured by JSR) 12 parts per 100 parts by mass of this pigment slurry Mass part, surface tension adjuster (trade name: “Dapro W-77”, San Nopco Co., Ltd.) 0.3 part by mass is added and stirred, water is further added, and an intermediate layer having a solid content concentration of 58% by mass is added. A coating solution was prepared. The static surface tension of the intermediate layer coating solution was 33 mN / m.

[Production of first adhesive]
50 parts by mass of 2-ethylhexyl acrylate, 48.5 parts by mass of butyl acrylate, 1 part by mass of acrylic acid, 0.5 parts by mass of ethylene glycol dimethacrylate, sodium polyoxyethylene alkyl ether sulfate (trade name: “Latemul WX” 4 parts by mass and 45 parts by mass of ion-exchanged water were taken and stirred vigorously to obtain an emulsified mixture of monomers.

  A reactor equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen introduction tube and a dropping funnel was charged with 15 parts by mass of ion-exchanged water, nitrogen was introduced, the temperature was raised to 80 ° C., and 10% with ion-exchanged water. 2 parts by weight of ammonium persulfate dissolved in The monomer emulsion previously adjusted to the beaker is dripped over 4 hours, and 3 mass parts of ammonium persulfate melt | dissolved with ion-exchange water is dripped in parallel. Emulsion polymerization is performed while maintaining the internal temperature at 80 to 85 ° C. After completion of dropping, the mixture was aged at the same temperature for 3 hours, and then cooled to room temperature to obtain a functional group-containing (meth) acrylic acid alkyl ester copolymer corresponding to the acrylic polymer (A) described above.

  66 parts by weight of butyl acrylate, 31.5 parts by weight of methyl methacrylate, 2 parts by weight of acrylic acid, 0.5 parts by weight of acetoacetoxyethyl methacrylate, sodium polyoxyethylene alkyl ether sulfate (trade name: “Latemul WX”, Kao 3.5 parts by mass and 52 parts by mass of ion-exchanged water were taken and stirred vigorously to obtain an emulsified mixture of monomers.

  In a reactor equipped with a stirrer, reflux condenser, thermometer, nitrogen introduction tube and dropping funnel, 45 parts by mass of ion-exchanged water, sodium polyoxyethylene alkyl ether sulfate (trade name: “Latemul WX”, manufactured by Kao Corporation) 0 Charge 4 parts by mass. Nitrogen was introduced, the temperature was raised to 80 ° C., and 2 parts by mass of ammonium persulfate dissolved in 10% with ion-exchanged water was charged. The monomer emulsion previously adjusted to the beaker is dripped over 4 hours, and 3 mass parts of ammonium persulfate melt | dissolved with ion-exchange water is dripped in parallel. Emulsion polymerization is performed while maintaining the internal temperature at 80 to 85 ° C. After completion of dropping, the mixture was aged at the same temperature for 3 hours, and then cooled to room temperature to obtain a copolymer emulsion corresponding to the vinyl polymer (B) described above.

  95 parts by mass of the above-mentioned functional group-containing (meth) acrylic acid alkyl ester copolymer, 5 parts by mass of tackifying resin-polymerized rosin pentaerythritol ester (trade name: “Superester E-650”, manufactured by Arakawa Chemical Industries) and the above Add 5 parts by weight of copolymer emulsion, add dioctylsulfosuccinic acid wetting agent and acetylenic diol leveling agent, adjust pH to about 8 with ammonia water, and apply first adhesive coating solution (static surface (Tension: 27 mN / m).

[Production of second adhesive]
A monomer mixture of 73 parts by mass of butyl acrylate, 20 parts by mass of 2-ethylhexyl acrylate, 6.5 parts by mass of methyl methacrylate, and 0.5 parts by mass of acrylic acid was added to a nonionic surfactant polyoxyethylene alkyl ether (product) Name: "Emulgen 930", manufactured by Kao Corporation) 1.0 part by mass, anionic surfactant polyoxyethylene alkyl ether sodium sulfate (trade name: "Lebenol WX", manufactured by Kao Corporation) 0.3 part by mass, ion exchange A pre-emulsion was prepared by adding and stirring in an aqueous surfactant solution of 30 parts by mass of water.

In a reaction vessel equipped with a stirrer, thermometer, and cooling tube, 1.0 part by mass of a nonionic surfactant polyoxyethylene alkyl ether (trade name: “Emulgen 930”, manufactured by Kao Corporation), anionic surface activity Sodium polyoxyethylene alkyl ether sulfate (trade name: “Lebenol WX”, manufactured by Kao) 0.9 parts by weight, sodium acetate 0.3 parts by weight, potassium persulfate 0.8 parts by weight, ion-exchanged water 30 parts by weight Was added, and the temperature of the solution was raised to 75 ° C. while stirring through nitrogen gas, 5/100 of the pre-emulsion was added, and initial polymerization was performed for 30 minutes. Thereafter, the remaining amount was dropped over 4 hours, and polymerization was carried out while maintaining the temperature at 75 to 80 ° C. After completion of the dropwise addition, the polymerization is further carried out by maintaining the temperature at 80 ° C., and a dioctylsulfosuccinic acid wetting agent and an acetylenic diol leveling agent are added to adjust the pH to about 8 with aqueous ammonia, (Tensile strength: 7.2 kg / cm ² , elongation: 1,050%, gel fraction: 34.5% by mass, static surface tension: 25 mN / m).

[Manufacture of adhesive sheet]
Three layers of the second adhesive (low temperature adhesion type acrylic emulsion type adhesive) / the intermediate layer coating solution / the first adhesive (general purpose type acrylic emulsion type adhesive) on the release sheet simultaneously with a slide hopper type curtain coater. After coating and drying, the heat-sensitive recording paper of Reference Example 1 was laminated to obtain the pressure-sensitive adhesive sheet of the present invention (coating speed: 600 m / min). The coating amount was the proportion of ^{7g / m 2 / 3g / m} 2 / 7g / m 2.

(Example 2)
[Manufacture of adhesive sheet]
In Example 1, except that in such a manner that the coating ratio of the second pressure-sensitive adhesive coating solution / the intermediate layer coating solution / first pressure-sensitive adhesive coating liquid and ^{10g / m 2 / 3g / m} 2 / 4g / m 2 is In the same manner as in Example 1, the pressure-sensitive adhesive sheet of the present invention was obtained.

(Example 3)
[Manufacture of intermediate layer coating solution]
Heavy calcium carbonate dispersion (trade name: “Kaidro Curve K-9”, manufactured by Bihoku Fuka Kogyo Co., Ltd.) and 100 parts by mass of oxidized starch (trade name: “Ace C”, manufactured by Oji Cornstarch Co., Ltd.), 5 parts by weight, styrene Add 12 parts by mass of butadiene copolymer latex (trade name: “0619”, manufactured by JSR) and 0.3 part by mass of a surface tension modifier (trade name: “Orphine E1010”, manufactured by Nissin Chemical Industry Co., Ltd.) The mixture was further stirred to prepare an intermediate layer coating solution having a solid content of 60% by mass. The static surface tension of the intermediate layer coating solution was 31 mN / m.

[Manufacture of adhesive sheet]
In Example 1, the adhesive sheet of this invention was obtained like Example 1 except having used the said intermediate | middle layer coating liquid.

Example 4
[Manufacture of intermediate layer coating solution]
90 parts by weight of plate-like kaolin (trade name: “Conzer 1500”, manufactured by Imerizu Minerals Japan), 0.1 part by weight of water and dispersant (trade name: “Aron A-9”, manufactured by Toagosei Co., Ltd.) And dispersed with a Coreless disperser to obtain a kaolin dispersion having a solid content of 70% by mass. In this dispersion, 5 parts by mass of oxidized starch (trade name: “ACE C”, manufactured by Oji Cornstarch Co., Ltd.), 12 parts by mass of styrene-butadiene copolymer latex (trade name: “0619”, manufactured by JSR), surface tension 0.3 parts by mass of a regulator (trade name: “Olfin E1010”, manufactured by Nissin Chemical Industry Co., Ltd.) was added and stirred, and water was further added to prepare an intermediate layer coating solution having a solid content of 57% by mass. The static surface tension of the intermediate layer coating solution was 35 mN / m.

[Manufacture of adhesive sheet]
In Example 1, the adhesive sheet of this invention was obtained like Example 1 except having used the said intermediate | middle layer coating liquid.

(Example 5)
[Manufacture of intermediate layer coating solution]
In Example 1, the intermediate | middle layer coating liquid was obtained like Example 1 except not having mix | blended the surface tension regulator with the intermediate | middle layer coating liquid. The static surface tension of the intermediate layer coating solution was 45 mN / m.

[Manufacture of adhesive sheet]
In Example 1, the adhesive sheet of this invention was obtained like Example 1 except having used the said intermediate | middle layer coating liquid.

(Example 6)
[Manufacture of adhesive sheet]
In Example 1, the pressure-sensitive adhesive coating solution of the present invention was obtained in the same manner as in Example 1 except that the wetting agent and the leveling agent were not added to the first and second pressure-sensitive adhesive coating solutions. The static surface tension of the first adhesive coating solution was 43 mN / m, and the static surface tension of the second adhesive coating solution was 42 mN / m.
The first pressure-sensitive adhesive coating solution / the same intermediate layer coating solution as in Example 5 / the second pressure-sensitive adhesive coating solution was applied to three layers simultaneously with a slide hopper die coater and dried, and then the thermal recording paper of Reference Example 1 was used. Were bonded together to obtain the pressure-sensitive adhesive sheet of the present invention (application speed: 500 m / min). The coating amount was the proportion of ^{7g / m 2 / 3g / m} 2 / 7g / m 2.

(Example 7)
[Manufacture of adhesive sheet]
In Example 1, the pressure-sensitive adhesive sheet of the present invention was obtained in the same manner as in Example 1 except that cast paper (trade name: “N Mirror 73”, manufactured by Oji Paper Co., Ltd.) was used instead of thermal paper as the surface substrate. It was.

(Comparative Example 1)
[Manufacture of release sheet]
After applying a solvent type silicone release agent (trade name: “Shin-Etsu Silicone KS-778”) to the surface of glassine paper having a basis weight of 85 g / m ² with a bar coater so as to be 0.8 g / m ² , hot air (140 C. for 60 seconds to obtain a release sheet.

[Manufacture of adhesive sheet]
On the surface of this release sheet, a general-purpose acrylic emulsion type pressure-sensitive adhesive A (trade name: “Olivein BPW-3110-1H”, manufactured by Toyo Ink Co., Ltd.) is reversely applied so that the dry coating amount is 8 g / m ^2. After coating with a roll coater, it was dried at 120 ° C. for 90 seconds. After the humidity of the back surface of the release sheet, the heat-sensitive recording paper of Reference Example 1 was bonded to obtain an adhesive sheet (C).
Next, a low temperature adhesion type acrylic emulsion type pressure-sensitive adhesive B (trade name: “Polytron CX-1083”, manufactured by Asahi Kasei Kogyo Co., Ltd.) polymerized using an anionic surfactant is dried on the surface of a separately prepared release sheet. After applying with a reverse roll coater so that the application amount is 8 g / m ² , the adhesive sheet (C) is dried on an unwinder while drying at 120 ° C. for 90 seconds and conditioning the release sheet back surface. The adhesive sheet having two adhesive layers was obtained by laminating two layers of the adhesive A and the adhesive B in the laminating nip while peeling the release sheet from the winding.

(Comparative Example 2)
In Example 1, a dioctyl sulfosuccinic acid wetting agent and an acetylenic diol leveling agent were added to 100 parts by mass of oxidized starch (trade name: “ACE C”, manufactured by Oji Cornstarch Co., Ltd.) as an intermediate layer coating solution, and stirred. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that water was added so that the solid content concentration was 22% by mass. (Static surface tension: 37 mN / m)

(Comparative Example 3)
In Example 1, a dioctylsulfosuccinic acid wetting agent and an acetylenic diol leveling agent were added to and stirred with a styrene-butadiene copolymer latex (trade name: “0619”, manufactured by JSR) as an intermediate layer coating solution. Further, water was added to obtain a pressure-sensitive adhesive sheet in the same manner as in Example 1 except that the solid concentration was 40% by mass. (Static surface tension: 35 mN / m)

[Evaluation methods]
(1) Adhesive strength: Adhesive strength to a polyethylene plate (manufactured by Nippon Test Panel Co., Ltd.) was measured at a predetermined temperature according to JIS Z 0237 (2000). One-year storage was performed in an environment of 20 ° C. and 65% RH. The same was true for the thermal paper coloring aptitude evaluation described below.

(2) Ouse: 100 sheets of A4 size adhesive sheets were stacked, and the cutting surface of the guillotine blade and the adhesive sheet when cut with a guillotine cutting machine was visually determined.
○: No pressure-sensitive adhesive sticks out and the guillotine blade and cut surface are not sticky.
Δ: The pressure-sensitive adhesive protrudes slightly, and the guillotine blade and the cut surface are sticky, but at a level that does not cause any problem in practice.
X: The sticking out of the pressure-sensitive adhesive is so severe that it causes a practical problem.

(3) Label processing suitability: The pressure-sensitive adhesive sheet finished in winding was subjected to label processing with a letterpress rotary label printing machine (trade name “SKP-250A type”, manufactured by Sanki Kikai Co., Ltd.) to evaluate the processing suitability.
A: There is no label rise or chipping, and the processability is very good.
○: There is almost no label rise or chipping, and the processability is excellent.
Δ: Slight label rise or chipping occurs, but at a level that is not a problem in practice.
X: The level of the rise of the label or chipping is severe and causes a practical problem.

(4) [Tensile Strength, Elongation] A pressure sensitive adhesive is applied to a release sheet so that the applied amount is 20 g / m ² and dried at 120 ° C. for 1 minute to prepare a sample film. The tensile strength and elongation of the obtained sample film were measured according to the JIS-K-6301 (1995) method.

(5) [Gel fraction] A pressure-sensitive adhesive is applied to a release sheet so as to have an application amount of 25 g / m ² and dried at 120 ° C. for 1 minute to prepare a sample film. The obtained sample film is cut into 3 cm × 3 cm, and the mass is measured (W1). This sample film is put into a basket made of a 300-mesh wire net whose mass has been measured in advance. Next, the whole wire mesh is immersed in 40 ml of tetrahydrofuran so that the entire sample film is attached and left for 24 hours. Thereafter, the whole wire mesh is taken out from tetrahydrofuran, and the sample film is further washed several times with fresh tetrahydrofuran, and then dried at room temperature for 1 day and further at 120 ° C. for 1 minute. The mass of the obtained film is measured (W2).
Gel fraction = W2 / W1 × 100 (%)

(6) Application suitability: Applicability with a coater when producing pressure-sensitive adhesive sheets in Examples and Comparative Examples was visually determined.
○: There is no problem in coating film formation, and no repelling or streak occurs. Δ: There is a problem in coating film formation, and the occurrence of repellency or stream is recognized, but it is a level at which there is no practical problem. There is a problem, repellency and streak occur frequently, and it is a level that causes a practical problem

(7) Thermal recording paper coloring suitability: The nine types of thermal recording adhesive sheets obtained in Examples and Comparative Examples were pressed against a hot plate at 120 ° C. for 5 seconds (39.2 N / cm ² ) to cause color development. The color density of the recorded image was measured in a visual mode of a Macbeth densitometer (trade name: RD-914, manufactured by Macbeth). Judgment was made as follows.
1.30 or more: high color density and excellent color development ability less than 1.30 1.10 or more: slightly lower color density, but less than 1.10, which is a practically no problem level: lower color density Is at a level that is severely problematic in practice.

(8) Comprehensive evaluation: Comprehensive evaluation as an adhesive sheet was performed.
A: Excellent as a pressure-sensitive adhesive sheet B: Excellent as a pressure-sensitive adhesive sheet B: Slightly problematic as a pressure-sensitive adhesive sheet, but at a level where there is no problem in practical use X: A level as problematic as a pressure-sensitive adhesive sheet is there.

  From Table 1, the pressure-sensitive adhesive sheets of the present invention of Examples 1 and 7 are excellent in adhesive force by forming a pressure-sensitive adhesive layer by three-layer simultaneous application by a curtain coating method, and the pressure-sensitive adhesive does not protrude, It was excellent in label processing suitability. In the pressure-sensitive adhesive sheet of Example 2 of the present invention, the amount of the second pressure-sensitive adhesive excellent in low-temperature adhesion suitability was large, so that the adhesive force was excellent, but the pressure-sensitive adhesive slightly protruded. Since the pressure-sensitive adhesive sheet of Example 3 of the present invention uses heavy calcium carbonate as a pigment for the intermediate layer, a tendency that the adhesive strength slightly decreases when stored as a pressure-sensitive adhesive sheet for a long period of time was observed. Since the adhesive sheet of Example 4 of the present invention uses the pigment kaolin of the intermediate layer, no decrease in adhesive strength and colorability was observed even when stored as an adhesive sheet for a long time. In Examples 5 and 6, since the static surface tension of the intermediate layer and / or pressure-sensitive adhesive layer coating solution was not controlled, some problems were observed in the coating suitability. On the other hand, in Comparative Example 1, the adhesiveness between the different pressure-sensitive adhesive layers was insufficient, the pressure-sensitive adhesive sticking out during label processing was severe, and the label processing suitability was poor. In Comparative Examples 2 to 3, since the pigment is not blended in the intermediate layer, the adhesiveness between the first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer is insufficient, and the pressure-sensitive adhesive protrudes during label processing. It was severe and inferior in label processing suitability.

  The pressure-sensitive adhesive sheet according to the present invention exhibited excellent pressure-sensitive adhesive performance in a temperature range of −10 to 50 ° C. and was excellent in label processing suitability.

Claims (9)

A surface base material, a first pressure-sensitive adhesive layer formed on the back surface side of the surface base material, an intermediate layer mainly composed of a pigment and a binder formed on the first pressure-sensitive adhesive layer, and the intermediate layer And a second pressure-sensitive adhesive layer formed on the pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet according to claim 1, wherein the pigment of the intermediate layer is a kaolin pigment. An acrylic polymer (A) in which the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer contains a functional group-containing (meth) acrylic acid alkyl ester copolymer (a) and a tackifier resin (b). The pressure-sensitive adhesive sheet according to claim 1 or 2, which is a pressure-sensitive adhesive mainly comprising a mixture of a vinyl polymer (B) having a glass transition temperature of -50 ° C to 50 ° C. The pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer is a non-ionic surfactant comprising a (meth) acrylic acid alkyl ester monomer made of polyoxyethylene alkyl ether, or an anionic surfactant and polyoxyethylene alkyl ether. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, which is a pressure-sensitive adhesive mainly composed of an acrylic copolymer that is emulsion-copolymerized using a nonionic surfactant. The pressure-sensitive adhesive sheet according to claim 4, wherein the surface substrate is a heat-sensitive recording paper. Three layers are applied simultaneously to the release sheet in the order of the second adhesive layer coating solution, the intermediate layer coating solution, and the first adhesive layer coating solution, and then dried and bonded to form a surface substrate. The manufacturing method of the adhesive sheet as described in any one of Claims 1-5 characterized by these. The manufacturing method of the adhesive sheet of Claim 6 whose static surface tension of the coating liquid for 1st and 2nd adhesive layers is 20-40 mN / m. The method for producing a pressure-sensitive adhesive sheet according to claim 6 or 7, wherein the intermediate surface coating solution has a static surface tension of 20 to 40 mN / m. The manufacturing method of the adhesive sheet as described in any one of Claims 6-8 which forms the coating liquid for adhesive layers, and an intermediate | middle layer coating liquid with a curtain coating system or a die coating system.