WO2014050369A1

WO2014050369A1 - Adhesive tape and method for producing adhesive tape

Info

Publication number: WO2014050369A1
Application number: PCT/JP2013/072189
Authority: WO
Inventors: 誠二秋山; 森野　彰規
Original assignee: Dic株式会社
Priority date: 2012-09-25
Filing date: 2013-08-20
Publication date: 2014-04-03
Also published as: JPWO2014050369A1; TW201420716A

Abstract

The present invention solves the problem of providing thin adhesive tape having excellent constant load-holding power. Another problem solved by the invention is providing thin adhesive tape having excellent constant load-holding power and bonding properties together with excellent removability. The invention pertains to adhesive tape having a total thickness of 120 μm or less, the adhesive tape being characterized in having an adhesive layer formed using a two-part cross-linkable water-dispersible acrylic adhesive containing an acrylic polymer and a cross-linking agent.

Description

Adhesive tape and method for producing adhesive tape

The present invention relates to a thin pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer formed using a two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive.

Adhesive tapes generally have high adhesion reliability and excellent workability when adhering two or more adherends. For example, adhesive tapes can be used for fixing parts in various fields including the electronic equipment field and the automobile field. It is used for attaching labels and labels.

As the pressure-sensitive adhesive tape, a pressure-sensitive adhesive tape obtained using a so-called solvent-based pressure-sensitive adhesive containing a volatile organic solvent is conventionally known as having excellent adhesiveness and holding power.

However, development of an adhesive tape obtained by using an aqueous adhesive instead of a solvent-based adhesive is demanded while the suppression of discharge of the organic solvent is demanded by the industry.

As the water-based pressure-sensitive adhesive, for example, a pressure-sensitive adhesive layer formed using a water-dispersed pressure-sensitive adhesive composition, a nonwoven fabric substrate as a support that supports the pressure-sensitive adhesive layer, The non-woven fabric substrate contains hemp as a constituent fiber and is processed with an impregnating agent selected from the group consisting of viscose and starch, and has a basis weight of 7 g / m <2>. A double-sided adhesive pressure-sensitive adhesive sheet is known which is a nonwoven fabric substrate of ˜17 g / m 2 (see, for example, Patent Document 1).

On the other hand, in the demand for thinner and lighter electronic devices, development of a thin adhesive tape with a thinner adhesive layer is underway as the adhesive tape.

However, since the water-based pressure-sensitive adhesive generally tends to be slightly inferior in terms of adhesiveness, holding power and the like as compared with the solvent-based pressure-sensitive adhesive, the thickness of the pressure-sensitive adhesive layer is required to make the pressure-sensitive adhesive tape thin. If the thickness is made thinner than before, the constant load holding force may be significantly reduced. The constant load holding force is a characteristic that does not cause the adhesive tape to peel off over time even when the adhesive tape is subjected to deformation for a long time, such as an electronic device used for a long period of time. This is one of the important characteristics for preventing product failure.

By the way, in recent years, in order to protect the global environment, products such as electronic devices are often disassembled after being used for a certain period of time. This is to recycle or reuse the parts that make up the product.

In order to disassemble the product and reuse the parts, it is necessary to peel off the adhesive tape used to fix the parts.

At that time, the adhesive tape is required to have removability, which is a property that does not cause destruction of the supporting base material when it is peeled off and does not cause adhesive residue on the part.

JP 2008-280439 A

The problem to be solved by the present invention is to provide a thin adhesive tape excellent in constant load holding force.

Also, the problem to be solved by the present invention is to provide a thin pressure-sensitive adhesive tape that is excellent in constant load holding force and adhesiveness and also excellent in the above-mentioned removability.

As a result of intensive studies to solve the above problems, when the total thickness of the pressure-sensitive adhesive tape is 120 μm or less, a two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive containing an acrylic polymer and a crosslinking agent is used. The present inventors have found that the above-mentioned problems can be solved by providing a pressure-sensitive adhesive layer formed in the above manner.

That is, the present invention is a pressure-sensitive adhesive tape having a total thickness of 120 μm or less, wherein the pressure-sensitive adhesive tape is formed using a two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive containing an acrylic polymer and a cross-linking agent. It is related with the adhesive tape characterized by having an adhesive layer.

Since the thin adhesive tape of the present invention has an excellent constant load holding force, it can be suitably used, for example, in the production scene of electronic devices, automobiles, etc., or when a label is attached.

The thin adhesive tape of the present invention is formed from a water-dispersed adhesive that can significantly reduce the discharge of volatile organic compounds (so-called VOC) and organic solvent odors. It can be suitably bonded, and even when stuck for a long time, the adhesive strength does not increase excessively, and when it is peeled off, it is not subjected to special treatment such as heating, so-called adhesive residue or destruction of the support substrate It is possible to realize good removability that is difficult to occur.

The pressure-sensitive adhesive tape of the present invention is a pressure-sensitive adhesive tape having a total thickness of 120 μm or less, and the pressure-sensitive adhesive tape uses a two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive containing an acrylic polymer and a crosslinking agent. It has the adhesive layer formed.

By using the two-component crosslinkable water-dispersible acrylic pressure-sensitive adhesive, it is easy to apply or impregnate the water-dispersible acrylic pressure-sensitive adhesive to a separator or a substrate in the production process of the pressure-sensitive adhesive tape. After that, the aqueous medium contained in the pressure-sensitive adhesive is removed, so that the crosslinking reaction between the acrylic copolymer and the crosslinking agent proceeds. As a result, the thin pressure-sensitive adhesive tape has a total thickness of 120 μm or less. Even if compared with the adhesive tape obtained using the conventional one-pack type adhesive, the outstanding constant load retention force can be provided.

The pressure-sensitive adhesive tape of the present invention may be a pressure-sensitive adhesive tape composed only of the pressure-sensitive adhesive layer, or a pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer on one or both sides of the substrate. It is preferable to use a pressure-sensitive adhesive tape provided with the pressure-sensitive adhesive layer on one side or both sides of the base material in order to achieve further excellent removability.

The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive tape may be a single-layer pressure-sensitive adhesive layer having a single composition or a multi-layered pressure-sensitive adhesive layer formed using a plurality of pressure-sensitive adhesives.

The pressure-sensitive adhesive tape provided with the pressure-sensitive adhesive layer on one side or both sides of the base material may be a single-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on one side of the base material, or a double-sided pressure-sensitive adhesive having a pressure-sensitive adhesive layer on both sides of the base material. It may be a tape. Among them, the double-sided pressure-sensitive adhesive tape is preferable because it can easily achieve the effects of the present invention, and is preferable because it can be suitably used for fixing two or more members.

The pressure-sensitive adhesive tape of the present invention can be used as a thin pressure-sensitive adhesive tape of a level that can cope with the reduction in thickness and weight of electronic devices and the cost reduction of the pressure-sensitive adhesive tape. The total thickness of the adhesive tape is 120 μm or less, preferably 30 μm to 120 μm, and more preferably 60 μm to 120 μm.

The thickness of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive tape is preferably 10 μm to 60 μm, and preferably 20 μm to 50 μm, in order to achieve both the thinness of the pressure-sensitive adhesive tape and excellent constant load retention. It is more preferable.

As the double-sided pressure-sensitive adhesive tape as the pressure-sensitive adhesive tape, the total thickness of the pressure-sensitive adhesive layers provided on both sides thereof is preferably 20 μm to 120 μm, more preferably 40 μm to 100 μm, and 60 μm to 100 μm. Is more preferable, and 80 μm to 100 μm is particularly preferable.

As the pressure-sensitive adhesive tape of the present invention, it is preferable to use a tape having a tensile strength of 20 N / 20 mm or more and less than 50 N / 20 mm in both the MD direction (longitudinal direction; flow direction) and the TD direction (transverse direction; width direction). It is more preferable to use a material having a tensile strength of 20 N / 20 mm or more and less than 40 N / 20 mm, and it is more preferable to use a material having a tensile strength of 30 N / 20 mm or more and less than 40 N / 20 mm. By using an adhesive tape having a tensile strength of 20 N / 20 mm or more, even when the adhesive tape is stuck to an adherend for a long time and then peeled again, the adhesive tape is difficult to break (hard to break). )Become. Moreover, even when the adhesive tape is applied to the curved surface portion of the adherend by using an adhesive tape having a tensile strength of less than 50 N / 20 mm, preferably less than 40 N / 20 mm, the repulsive force of the adhesive tape It is possible to prevent the adhesive tape from peeling off due to the above. The tensile strength is the maximum measured with a sample line length of 100 mm and a width of 20 mm, using a Tensilon tensile tester in an environment of 23 ° C. and 50% RH under a measurement condition of a tensile speed of 300 mm / min. Refers to strength.

The pressure-sensitive adhesive tape is, for example, a two-component cross-linkable water dispersibility obtained by mixing an acrylic pressure-sensitive adhesive composition, which is an acrylic polymer aqueous dispersion in which an acrylic polymer is dispersed in an aqueous medium, and a crosslinking agent. A method of removing an aqueous medium by applying or impregnating an acrylic adhesive on one or both sides of a substrate using a roll coater or die coater, etc., followed by drying (direct coating method), a separator such as a release film The adhesive layer formed by applying the two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive to the substrate using a roll coater or a die coater and removing the aqueous medium by drying is applied to one or both sides of the substrate. It can be manufactured by a transfer method (transfer method).

Compared to the direct coating method in which a base material such as a nonwoven fabric is impregnated with the two-component crosslinkable water-dispersible acrylic pressure-sensitive adhesive, the transfer method transfers the dried pressure-sensitive adhesive layer formed on the surface of the separator to the nonwoven fabric. Since it is an impregnation method, the impregnation property tends to be slightly inferior. However, the dried pressure-sensitive adhesive layer formed using the two-component cross-linking pressure-sensitive adhesive composition does not progress so much in the period of about 48 hours after the drying, and the gel fraction Therefore, even if the above transfer method is adopted, the nonwoven fabric is excellent in impregnation properties.

In addition, it is preferable that a separator is laminated on the surface of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive tape obtained by the above-described method until the pressure-sensitive adhesive tape can be handled.

The two-component water-dispersible acrylic pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive tape is an acrylic polymer aqueous dispersion in which an acrylic polymer produced in advance is dispersed in an aqueous medium. What mixed the acrylic adhesive composition and the crosslinking agent before use is mentioned.

As the acrylic pressure-sensitive adhesive composition, an acrylic polymer or the like dispersed in an aqueous medium can be used.

The acrylic polymer is not particularly limited as long as it can form acrylic polymer emulsion particles in an aqueous medium.

As the acrylic polymer, those obtained by polymerizing various monomers can be used.

As the monomer, a (meth) acrylate having an alkyl group having 1 to 12 carbon atoms can be suitably used as a main monomer component.

Examples of the (meth) acrylate having an alkyl group having 1 to 12 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) ) Acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. may be used alone or in combination of two or more. it can.

As the (meth) acrylate having an alkyl group having 1 to 12 carbon atoms, 2-ethylhexyl acrylate is used among the above-described ones, and it has excellent removability and constant load holding power even if it is thin. It is preferable when obtaining an adhesive tape.

Further, as the monomer, by using in combination with the 2-ethylhexyl acrylate and a (meth) acrylate having an alkyl group having 4 to 8 carbon atoms other than 2-ethylhexyl acrylate, it is excellent even if it is thin. It is preferable because a pressure-sensitive adhesive tape having both removability and excellent constant load retention can be obtained.

Examples of the (meth) acrylate having an alkyl group having 4 to 8 carbon atoms other than 2-ethylhexyl acrylate include n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, isooctyl (meta ) Acrylates and (meth) acrylates such as n-octyl (meth) acrylate can be used. Among them, it is preferable to use an acrylate having an alkyl group having 4 to 8 carbon atoms, and it is particularly preferable to use n-butyl acrylate. Further, n-butyl acrylate and t-butyl methacrylate may be used in combination.

When (meth) acrylate having an alkyl group having 4 to 8 carbon atoms other than 2-ethylhexyl acrylate and 2-ethylhexyl acrylate is used in combination, excellent re-peelability and constant load retention are compatible even when thin. In order to obtain a pressure-sensitive adhesive tape, it has an alkyl group having 4 to 8 carbon atoms (meth) other than 2-ethylhexyl acrylate and 2-ethylhexyl acrylate with respect to the total amount of monomers used in the production of the acrylic polymer. The total amount of acrylate is preferably 50% by mass to 98% by mass, and more preferably 80% by mass to 98% by mass.

The mass ratio of 2-ethylhexyl acrylate to (meth) acrylate having an alkyl group having 4 to 8 carbon atoms other than 2-ethylhexyl acrylate is [2-ethylhexyl acrylate / alkyl having 4 to 8 carbon atoms]. (Meth) acrylate having a group] = 90/10 to 20/80 is preferable, and 75/25 to 25/75 is more preferable.

In addition to those described above, monomers that can be used in the production of the acrylic polymer include methyl (meth) acrylate and ethyl (meth) acrylate for the purpose of further improving the cohesive strength of the pressure-sensitive adhesive layer. It is preferable to use a (meth) acrylate having an alkyl group having 2 or less carbon atoms such as The (meth) acrylate having an alkyl group having 2 or less carbon atoms is preferably in the range of 1% by mass to 10% by mass with respect to the total amount of the monomer.

As the monomer that can be used for the production of the acrylic polymer, in addition to those described above, a monomer having an acid group may be used for the purpose of further improving the cohesive force of the pressure-sensitive adhesive layer. Can do.

Examples of the monomer having an acid group include one or more carboxyl group-containing vinyl monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, phthalic acid, phthalic anhydride, and crotonic acid. Two or more types can be used. Among these, it is more preferable to use at least one selected from the group consisting of acrylic acid and methacrylic acid in order to form a pressure-sensitive adhesive layer that has both a more excellent constant load holding force and removability.

The acid group-containing monomer is preferably used in an amount of 0.5 to 10% by mass relative to the total mass of monomers used for the production of the acrylic polymer. More preferably, it is used in the range of 5% by mass to 5% by mass.

As the monomer that can be used for the production of the acrylic polymer, it is preferable to use a vinyl monomer having a nitrogen atom in addition to the above-mentioned monomers.

The vinyl monomer having a nitrogen atom can impart suitable removability to the pressure-sensitive adhesive layer by interacting with an acid group, particularly a carboxyl group, which the acrylic polymer may have. .

Examples of the vinyl monomer having a nitrogen atom include 1 or 2 of N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylonitrile, acrylamide, N, N-dimethylacrylamide, dimethylaminoethyl (meth) acrylate and the like. It can be used above.

The vinyl monomer having a nitrogen atom is preferably 0.1% by mass to 4.5% by mass with respect to the total mass of monomers that can be used for the production of the acrylic polymer. More preferably, it is used in the range of 5% by mass to 3.5% by mass.

The acrylic pressure-sensitive adhesive composition, which is an acrylic polymer aqueous dispersion in which the acrylic polymer is dispersed in an aqueous medium, can be produced by an emulsion polymerization method. Specifically, an acrylic polymer aqueous dispersion in which an acrylic polymer is dispersed in an aquatic medium by emulsion polymerization of the monomer in the presence of a polymerization initiator, an aqueous medium, an emulsifier, or the like. A system pressure-sensitive adhesive composition can be obtained.

As the polymerization initiator, a conventionally known azo initiator or the like can be used.

As the emulsifier, an anionic emulsifier, a nonionic emulsifier, and other dispersion stabilizers can be used in appropriate amounts in order to ensure the stability of the emulsion polymerization.

Examples of the anionic emulsifier include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate and the like. Oxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and the like can be used.

Further, as the emulsifier, it is preferable to use an emulsifier having a polymerizable unsaturated group in the molecule, called “reactive emulsifier”. Specifically, Latemul S-180 [manufactured by Kao Corporation], Latemu PD-104 [manufactured by Kao Corporation], Aqualon HS-10 [manufactured by Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon HS-20 [No. Ichi Kogyo Seiyaku Co., Ltd.], Aqualon KH-10 [Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon KH-1025 [Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon KH-05 [Daiichi Kogyo Seiyaku Co., Ltd. )], Aqualon RN-10 [Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon RN-20 [Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon ER-10 [Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon ER-20 [Daiichi Kogyo Seiyaku Co., Ltd.], New Frontier A-229E [Daiichi Kogyo Seiyaku Co., Ltd.], Adekaria Soap SE-10 [Adeka Co., Ltd.], Adekaria Soap SE-20 [Adeka Co., Ltd.], ADEKA Asopu SR-10 N [(Ltd.) ADEKA Ltd.], ADEKAREASOAP SR-20 N [(Ltd.) ADEKA Ltd.] and the like. It is preferable to use the reactive emulsifier because it can improve the polymerization stability when producing the acrylic polymer and can improve the water resistance of the pressure-sensitive adhesive layer.

As an aqueous medium in which the acrylic polymer can be dispersed, water alone or a mixed solvent of water and a water-soluble solvent can be used. The “mixed solvent of water and a water-soluble solvent” is a mixed solvent of a water-soluble solvent mainly composed of water, and the content of the water-soluble solvent is preferably 10 with respect to the total amount of the mixed solvent. It is preferable to use those that are not more than wt%, more preferably not more than 5 wt%.

As the water-soluble solvent, for example, alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, ethyl carbitol, ethyl cellosolve, butyl cellosolve, and polar solvents such as N-methylpyrrolidone may be used alone or in combination. it can.

As the acrylic polymer obtained by the above method, those having a weight average molecular weight in the range of 300,000 to 1,200,000 are preferably used, and those having a weight average molecular weight in the range of 400,000 to 1,000,000 are used. More preferably, those having a weight average molecular weight in the range of 600,000 to 800,000 are more preferably used. By using an acrylic polymer having a weight average molecular weight in the above-mentioned range, it is possible to achieve a more balanced constant load holding force, adhesiveness, and removability in a balanced manner. In addition, the said weight average molecular weight is standard polystyrene conversion by a gel permeation chromatography (GPC). As measurement conditions, TSKgel GMHXL [manufactured by Tosoh] is used as the column, the column temperature is 40 ° C., the eluent is tetrahydrofuran, the flow rate is 1.0 mL / min, and the standard polystyrene is TSK standard polystyrene.

As a method for adjusting the weight average molecular weight, a chain transfer agent may be used as necessary. Examples of the chain transfer agent include known chain transfer agents such as lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimethylcapto-1-propanol. Can be used.

The amount of the chain transfer agent used can be appropriately adjusted according to the production conditions of the acrylic polymer. Depending on production conditions, when adjusting the weight average molecular weight of the acrylic polymer to the preferred range, when using lauryl mercaptan, the total amount of monomers constituting the acrylic polymer. On the other hand, it is preferably used in the range of 0.01% by mass to 0.1% by mass, more preferably in the range of 0.02% by mass to 0.07% by mass, and 0.03% by mass to 0%. It is particularly preferable to use in the range of 0.05 mass%. By producing the acrylic polymer with the use amount in the above range, it is possible to achieve a more excellent balance between constant load retention, adhesiveness, and removability in a balanced manner.

As the acrylic polymer, those having an average particle diameter exceeding 150 nm are preferably used, more preferably those having an average particle diameter of 200 nm to 1000 nm, and an average particle diameter of 200 nm to 800 nm being used. It is more preferable to use those having an average particle diameter of 200 nm to 600 nm, particularly preferable to use those having an average particle diameter of 250 nm to 400 nm.

The average particle diameter refers to a 50% median diameter on the volume basis of particles made of an acrylic polymer, and is a value obtained by measurement by a dynamic light scattering method.

The acrylic pressure-sensitive adhesive composition produced by the above method is 40% by mass to 70% by mass in order to reduce the manufacturing cost and transportation cost and further improve the drying property when forming the pressure-sensitive adhesive layer. It is preferable to use one having a solid content concentration in the range.

As the acrylic pressure-sensitive adhesive composition, a composition containing a tackifying resin can be used as needed for the purpose of imparting excellent constant load holding power and tackiness to the pressure-sensitive adhesive layer.

As the tackifying resin, an emulsion-type tackifying resin can be preferably used when used for a water-dispersed acrylic pressure-sensitive adhesive. As the emulsion type tackifying resin, rosin-based tackifying resin, polymerized rosin-based tackifying resin, polymerized rosin ester-based tackifying resin, rosin phenol-based tackifying resin, stabilized rosin ester-based tackifying resin, disproportionation A rosin ester tackifier resin, a terpene tackifier resin, a terpene phenol tackifier resin, a petroleum resin tackifier resin, or the like can be used.

Among these, it is preferable to use a polymerized rosin ester-based tackifying resin or a rosin phenol-based tackifying resin, and it is more preferable to use these in combination in order to obtain a pressure-sensitive adhesive tape with further improved constant load holding power and adhesiveness. preferable.

Examples of the polymerized rosin ester-based tackifying resin include Superester E-650 (manufactured by Arakawa Chemical Industry Co., Ltd.), Superester E-788 (manufactured by Arakawa Chemical Industry Co., Ltd.), Superester E-786-60 [Arakawa Chemical Industry Co., Ltd.], Super Ester E-865 [Arakawa Chemical Industry Co., Ltd.], Super Ester E-865NT [Arakawa Chemical Industry Co., Ltd.], Harrier Star SK-508 [Harima Kasei Co., Ltd.] ] Harrier Star SK-508H [manufactured by Harima Kasei Co., Ltd.], Harrier Star SK-816E [manufactured by Harima Kasei Co., Ltd.], Harrier Star SK-822E [manufactured by Harima Kasei Co., Ltd.], Harrier Star SK-323NS [Harima Kasei Co., Ltd.] can be used.

The rosin phenol-based tackifying resins are Tamanoru E-100 [Arakawa Chemical Industries, Ltd.], Tamano E-200 [Arakawa Chemical Industries, Ltd.], Tamano E-200NT [Arakawa Chemical Industries, Ltd.] Etc. can be used.

The mass ratio of the polymerized rosin ester tackifier resin and the rosin phenol tackifier resin is preferably [polymerized rosin ester tackifier resin / rosin phenol tackifier resin] = 5/1 to 1/5. 3/1 to 1/3 is more preferable, and 1/1 to 1/3 is more preferable because a pressure-sensitive adhesive layer in which the constant load holding force and the removability are improved in a balanced manner can be formed.

As the tackifying resin, those having a softening point in the range of 120 ° C. to 180 ° C. are preferably used, and those having a softening point in the range of 140 ° C. to 180 ° C. are excellent in each stage. It is preferable for forming an adhesive layer having a constant load holding force.

The tackifying resin is preferably used in the range of 10 to 40 parts by mass, more preferably in the range of 15 to 40 parts by mass with respect to 100 parts by mass of the acrylic polymer. The use in the range of 15 to 35 parts by mass is preferable because the removability and the constant load holding force can be improved in a balanced manner.

The acrylic pressure-sensitive adhesive composition may contain various additives as required.

Examples of the additive include a base for adjusting pH (such as aqueous ammonia), an acid, a plasticizer, a softening agent, an antioxidant, a filler such as glass or plastic fibers, balloons, beads, metal powder, Known colorants such as pigments and dyes, pH adjusters, film forming aids, leveling agents, thickeners, water repellents, antifoaming agents and the like can be used.

As the two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive used for producing the pressure-sensitive adhesive tape of the present invention, a mixture of the acrylic pressure-sensitive adhesive composition and a cross-linking agent can be used. Mixing of the acrylic pressure-sensitive adhesive composition and the cross-linking agent is performed before applying the two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive to the surface of a base material, a separator, etc., and has excellent constant load holding power. It is preferable for obtaining a thin adhesive tape.

Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, a polyvalent metal salt crosslinking agent, a metal chelate crosslinking agent, a keto-hydrazide crosslinking agent, an oxazoline crosslinking agent, and a carbodiimide crosslinking agent. A crosslinking agent, a silane crosslinking agent, a glycidyl (alkoxy) epoxysilane crosslinking agent, or the like can be used. Among them, it is possible to use an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a keto-hydrazide-based crosslinking agent, an oxazoline-based crosslinking agent, a silane-based crosslinking agent, and an epoxysilane-based crosslinking agent. The initial gel fraction of the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive can be adjusted to 15% by mass or less, and is preferable for forming a pressure-sensitive adhesive layer having a gel fraction of 30% by mass or more after curing. It is particularly preferable to use a crosslinking agent or an epoxy compound.

Specific examples of the crosslinking agent include Vernock DNW-5000 (manufactured by DIC Corporation), Bernock DNW-5010 [manufactured by DIC Corporation], and Bernock DNW-5100 [DIC Corporation) as long as they are isocyanate crosslinking agents. )], Bernock Sakai DNW-5500 [manufactured by DIC Corporation], Aquanate 100 [manufactured by Nippon Polyurethane Industry Co., Ltd.], Aquanate 105 [manufactured by Nippon Polyurethane Industry Co., Ltd.], Aquanate 110 [Japan Polyurethane Industry ( Co., Ltd.], Aquanate 120 [Nihon Polyurethane Industry Co., Ltd.], Aquanate 130 [Nihon Polyurethane Industry Co., Ltd.], Aquanate 200 [Nihon Polyurethane Industry Co., Ltd.], Aquanate 210 [Nihon Polyurethane] Industrial Co., Ltd.], LS2319 [Sumika Bayer Urethane Co., Ltd.], L 2336 [manufactured by Sumika Bayer Urethane Co., Ltd.], Bayhydr 3100 [manufactured by Sumika Bayer Urethane Co., Ltd.] and the like, and Denacol EX-832 [manufactured by Nagase Kasei Kogyo Co., Ltd.] EX-841 [manufactured by Nagase Kasei Kogyo Co., Ltd.], Tetrad C [manufactured by Mitsubishi Gas Chemical Co., Ltd.], Tetrad X [manufactured by Mitsubishi Gas Chemical Co., Ltd.], etc. -500 [manufactured by Nippon Shokubai Co., Ltd.], Epocross WS-700 [manufactured by Nippon Shokubai Co., Ltd.], Epocross K-2010E [manufactured by Nippon Shokubai Co., Ltd.], Epocross K-2020E [manufactured by Nippon Shokubai Co., Ltd.] Epocros K-2030E [manufactured by Nippon Shokubai Co., Ltd.], and carbodiimide-based crosslinking agents such as Carbodilite SV-02 [Nisshinbo Co., Ltd.] Carbodilite V-02 [Nisshinbo Co., Ltd.], Carbodilite V-02-L2 [Nisshinbo Co., Ltd.], Carbodilite V-04 [Nisshinbo Co., Ltd.], Carbodilite E-01 [Nisshinbo Co., Ltd.], Carbodilite E-02 [Nisshinbo Co., Ltd.], Carbodilite E-03A [Nisshinbo Co., Ltd.], Carbodilite E-04 [Nisshinbo Co., Ltd.], and any glycidyl (alkoxy) epoxysilane crosslinking agent 2- (3,4-epoxycyclohexylethyltrimethoxysilane [KBM-303; manufactured by Shin-Etsu Silicone Co., Ltd.], γ-glycidoxypropyltrimethoxysilane [KBM-403; manufactured by Shin-Etsu Silicone Co., Ltd.], γ -Glycidoxypropylmethyldiethoxysilane [KBE-402; manufactured by Shin-Etsu Silicone Co., Ltd.], γ-glycidoxypropi Triethoxysilane [KBE-403; manufactured by Shin-Etsu Silicone Co., Ltd.], and the like.

The cross-linking agent may be appropriately adjusted according to the type of the cross-linking agent, but is preferably used in the range where the gel fraction of the pressure-sensitive adhesive layer after cross-linking is 30% by mass to 60% by mass, and 35% by mass. More preferably, it is used in the range of ˜50% by mass, and more preferably in the range of 35% by mass to 45% by mass.

The initial gel fraction of the two-component cross-linking acrylic pressure-sensitive adhesive obtained by mixing the acrylic pressure-sensitive adhesive composition and the cross-linking agent is preferably 15% by mass or less, and preferably 10% by mass or less. More preferably, it is 5% by mass or less, more preferably 1% by mass to 3% by mass. By using a pressure-sensitive adhesive having an initial gel fraction in the above range, a pressure-sensitive adhesive tape having suitable constant load holding power and removability can be obtained.

In addition, the said initial gel fraction points out the value measured by the method described in the column (measurement of the gel fraction immediately after a drying process) in the Example mentioned later.

When the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive tape of the present invention is obtained by crosslinking reaction of the two-liquid cross-linking acrylic pressure-sensitive adhesive to form a pressure-sensitive adhesive tape excellent in constant load retention. preferable.

The pressure-sensitive adhesive layer preferably has a crosslinked structure with a gel fraction of 30% by mass to 60% by mass, and has a crosslinked structure with an amount of 35% by mass to 50% by mass. It is more preferable that a pressure-sensitive adhesive layer having a suitable cohesive strength can be obtained by having a cross-linked structure of 35% by mass to 45% by mass. And an adhesive tape excellent in the constant load holding force can be obtained.

In addition, the gel fraction of the pressure-sensitive adhesive layer in which the crosslinked structure is formed refers to a value measured by the method described in the column of (Measurement of gel fraction of pressure-sensitive adhesive layer of pressure-sensitive adhesive tape) in Examples described later.

The pressure-sensitive adhesive layer preferably has a temperature exhibiting a convex peak value on the tangent loss in the dynamic viscoelastic spectrum, which is −60 ° C. to −5 ° C., and preferably −30 ° C. to −10 ° C. More preferred. When it exists in this range, it becomes easy to make re-peelability and constant load holding power compatible with balance.

The pressure-sensitive adhesive tape of the present invention is formed by, for example, applying a two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive to the surface of a release-treated separator, drying, and then curing for a certain period to form a cross-linked structure. Thus, it is possible to manufacture a so-called baseless adhesive tape.

Also, among the pressure-sensitive adhesive tapes of the present invention, a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on one or both sides of the substrate can be produced by the direct coating method or the transfer method.

When using a non-woven fabric base or a foam base as the base, a part of the pressure-sensitive adhesive layer may be impregnated in the base.

When the pressure-sensitive adhesive layer is formed by the direct coating method, a two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive is applied to the substrate, and immediately after drying at a temperature of 80 ° C. to 120 ° C. for about 1 second to 5 minutes. The initial gel fraction of the pressure-sensitive adhesive layer is preferably 15% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, and 1% by mass to 3% by mass. Is more preferable. When the pressure-sensitive adhesive layer is formed by the transfer method, a two-liquid cross-linkable water-dispersible acrylic pressure-sensitive adhesive is applied to the surface of a separator such as a release film, and the temperature is 80 ° C. to 120 ° C. for 1 second to 5 minutes. The initial gel fraction of the pressure-sensitive adhesive layer immediately after being dried to a certain extent is preferably 15% by mass or less, more preferably 10% by mass or less, and further preferably 7% by mass or less. The lower limit of the initial gel fraction is preferably 0% by mass.

The pressure-sensitive adhesive layer is further cured under an environment of 30 ° C. to 60 ° C. for a period of about 1 day to 10 days, whereby a crosslinking reaction proceeds. As a result, preferably 30% by mass to 60% by mass. The pressure-sensitive adhesive layer having a gel fraction of 35% by mass to 50% by mass, more preferably 35% by mass to 45% by mass is formed. Thereby, the adhesive tape excellent in constant load holding power, adhesiveness, and removability can be obtained.

As the base material that can be used when producing the adhesive tape, the base material to be used is not particularly limited, and various plastic films, papers, cloths, rubber sheets, foam sheets, metal foils, these A complex or the like can be appropriately selected and used.

When producing a double-sided pressure-sensitive adhesive tape used for fixing between parts, it is preferable to use a non-woven fabric as a base material, and the non-woven fabric has a tensile strength in order to balance re-peelability and adhesion. It is preferable to use a nonwoven fabric having tear strength and interlayer strength within a specific range.

The tensile strength of the nonwoven fabric is preferably 10 to 50 N / 20 mm in both the MD direction (longitudinal direction; flow direction) and the TD direction (lateral direction; width direction), more preferably 15 to 40 N / 20 mm, and more preferably 25 to 40 N / 20 mm. Even more preferred. By setting the tensile strength of the nonwoven fabric within the above range, it is possible to obtain a pressure-sensitive adhesive tape that is less likely to be cut off during re-peeling and that does not easily peel off when applied to a curved surface or the like. In addition, the above-mentioned tensile strength is measured using a Tensilon tensile tester on an adhesive tape having a vote line length of 100 mm and a width of 20 mm under a measurement condition of a tensile speed of 300 mm / min in an environment of 23 ° C. and 50% RH. The maximum strength.

The tear strength of the nonwoven fabric is preferably 1 N or more in terms of the tear strength specified in JIS-P-8116. By setting the tear strength to 1 N or more, the breakage of the nonwoven fabric that occurs when the starting point of breakage occurs due to the instantaneous tearing in the peeling process and expands can be remarkably suppressed, and the nonwoven fabric becomes difficult to break. As a result, the removability of the pressure-sensitive adhesive tape adhered to the adherend for a long time can be greatly improved. The upper limit of the tear strength is not particularly defined, but a tear strength of about 3N is usually assumed as the upper limit for a substrate using a nonwoven fabric. Preferably it is 1.2 to 2.5N, more preferably 1.5 to 2.5N.

The interlayer strength of the nonwoven fabric is preferably 1 N / 15 mm or more. As a method for measuring the interlayer strength, a sample is first prepared by sticking a 24 mm wide adhesive film (CT405AP-24 manufactured by Nichiban Co., Ltd.) on both sides of a 25 × 150 mm non-woven fabric. The length of the adhesive film is longer than that of the nonwoven fabric. Both ends of the sample are cut, the adhesive film is peeled off from one end of the sample adjusted to 15 × 150 mm, and the nonwoven fabric layer is peeled off by about 30 mm. Three samples of each of the vertical direction and the horizontal direction are prepared. Measurement temperature and humidity: 23 ° C., 50% RH, Measuring instrument: Tensilon RTA-100 manufactured by Orientec, sample gripping distance: 20 mm, the sample is sandwiched between chucks, speed: 100 mm / min, measurement distance: 50 mm The integrated average load is read, and the average value of the three sheets in the vertical direction and the horizontal direction is set as the interlayer strength (N / 15 mm). The upper limit of interlaminar strength is not particularly specified, but an interlaminar strength of about 4N is usually assumed as the upper limit for a substrate using a nonwoven fabric.

As the material of the nonwoven fabric, a known and conventional nonwoven fabric used as a base material for an adhesive tape can be used. Typical examples include Manila hemp; pulp; chemical fibers such as rayon, acetate fiber, polyester fiber, polyvinyl alcohol fiber, polyamide fiber; and mixtures thereof. Furthermore, you may perform the impregnation process which used the viscose impregnation and the thermoplastic resin as a binder as needed.

Among these, hemp alone or a mixture of hemp and vinylon, rayon, polyester, pulp or the like is preferable. As the hemp, Manila hemp is preferable from the viewpoint of strength. The content of Manila hemp is preferably 50% by mass or more, and more preferably 70% by mass or more.

Further, for the purpose of improving the strength of the nonwoven fabric, it is preferable to add a known and usual reinforcing agent in the nonwoven fabric manufacturing process. As the reinforcing agent, an internal additive reinforcing agent or an external additive reinforcing agent may be used alone or in combination. As the internal reinforcement, polyacrylamide resin, urea-formaldehyde resin, melamine-formaldehyde resin, epoxy-polyamide resin, etc. can be used. In particular, a polyamidoamine / epichlorohydrin resin, which is an epoxy-polyamide resin, is preferable because it significantly increases the interlayer strength of the nonwoven fabric. The amount of the internal additive reinforcing agent added is preferably 0.2% by mass to 1% by mass and more preferably 0.3% by mass to 0.5% by mass with respect to the nonwoven fabric. On the other hand, as the external additive reinforcing agent, a thermoplastic resin such as starch; viscose, carboxymethylcellulose, polyvinyl alcohol, polyacrylamide or the like can be used. Especially, in order to raise the interlayer intensity | strength of a nonwoven fabric base material, it is preferable to use the above-mentioned internal additive reinforcement agent.

The basis weight of the nonwoven fabric is preferably 10 g / m ² to 30 g / m ² , more preferably 13 g / m ² to 25 g / m ² , and 14 g / m ² to 20 g / m ^2. Even more preferred. The density is preferably 0.1 g / cm ³ to 0.8 g / cm ³ , more preferably 0.2 g / cm ³ to 0.4 g / cm ³ . In the case of this range, it is possible to improve the balance between the difficulty of cutting the nonwoven fabric and the impregnation property of the pressure-sensitive adhesive into the nonwoven fabric, and the removability can be further improved.

The non-woven fabric has a thickness of preferably 100 μm or less, more preferably 10 μm to 100 μm, and further preferably 12 μm to 100 μm.

The paper making method of the nonwoven fabric is not particularly limited, but can be obtained by a known wet method, and various paper machines using a circular net paper machine, a short net paper machine, a long net paper machine, an inclined short net paper machine, etc. The method is used. Among them, in order to make it difficult to cut the nonwoven fabric, it is preferable to increase the isotropy of strength and elongation in the MD direction and the TD direction, and an inclined short net paper machine that easily increases the isotropy is preferable.

Since the pressure-sensitive adhesive tape of the present invention is excellent in constant load holding force and adhesiveness, it is also excellent in strong pressure-sensitive adhesive force capable of stably fixing members such as fixing between parts in a small area. In addition, the pressure-sensitive adhesive tape of the present invention has excellent removability when the adhesive defect in the work process and the members at the time of recycling are separated. In addition, since a water-dispersed acrylic pressure-sensitive adhesive composition can be used instead of a pressure-sensitive adhesive mainly composed of a conventional solution polymerization type acrylic resin, a reduction effect of volatile organic compounds can also be expected. It can be suitably used as an adhesive tape that fixes parts in various products in industrial applications such as building materials, OA, and home appliance industries.

Next, the present invention will be described in detail with reference to examples and comparative examples.

[Method for producing nonwoven fabric substrate (x1)]
Paper making a solution containing 100% by mass of Manila hemp with a basis weight of 17.5 g / m ² and a density of 0.32 g / cm ³ gives a tensile strength of 22.1 N / 20 mm in the MD direction and 20 in the TD direction. A nonwoven fabric substrate (x1) having a thickness of 5 N / 20 mm was obtained.

[Production Method of Nonwoven Fabric Base (x2)]
A paper solution containing 90% by weight of Manila hemp, 10% by weight of polyester, and 0.5% by weight of polyamidoamine / epichlorohydrin resin is made into a paper having a basis weight of 17 g / m ² and a density of 0.28 g / cm 3. To obtain a nonwoven fabric substrate (x2) of 25.3 N / 20 mm and 23.5 N / 20 mm in the TD direction.

(Preparation Example 1) Preparation of water-dispersible acrylic pressure-sensitive adhesive composition (1) In a container, 75.0 g of ion exchange water and Aqualon KH-1025 as a surfactant [Daiichi Kogyo Seiyaku Co., Ltd .; active ingredient 25 20.0 g [mass%] and 37.5 g of Latemul PD-104 [manufactured by Kao Corporation; active ingredient 20 mass%] as a surfactant were added and dissolved uniformly. There, 227.5 g of n-butyl acrylate, 227.5 g of 2-ethylhexyl acrylate, 25.0 g of methyl methacrylate, 7.5 g of N-vinylpyrrolidone, 1.5 g of acrylic acid, 11.0 g of methacrylic acid, 0.2 g of lauryl mercaptan Was added and emulsified to obtain 632.7 g of an emulsified liquid (1).

340 g of ion-exchanged water was placed in a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, and the temperature was raised to 60 ° C. while blowing nitrogen. While stirring, a part [3.2 g] of the emulsion (1), 5.0 g of ammonium persulfate aqueous solution [3% by mass of active ingredient], 5.0 g of sodium hydrogen sulfite aqueous solution [3% by mass of active ingredient] were added. Polymerization was carried out in 1 hour while maintaining the temperature. Subsequently, the remaining emulsion (1) 629.5 g and ammonium persulfate aqueous solution 40 g [active ingredient 1.25%] were dropped and polymerized using a separate funnel over 8 hours while maintaining the reaction vessel at 60 ° C. . After completion of the dropping, the reaction vessel was stirred for 2 hours while maintaining the temperature at 60 ° C., then the contents were cooled, and subsequently adjusted with ammonia water (active ingredient 10% by mass) so that the pH was 7.5. This was filtered through a 200-mesh wire mesh to obtain 1013.5 g of an acrylic polymer emulsion (1). The acrylic polymer emulsion (1) thus obtained had a solid content concentration of 50% by mass, and the acrylic polymer had an average particle size of 341 nm. The weight average molecular weight of the acrylic polymer contained in the acrylic polymer emulsion (1) was 770,000.

In 1000 g of the acrylic polymer emulsion (1), Surfinol PSA-336 [produced by Air Products Japan Co., Ltd .; active ingredient 100 mass%] 2.5 g as a leveling agent, Surfynol DF-110D as an antifoaming agent [Air Products Japan Co., Ltd .; active ingredient 100% by mass] 2.5 g, Superester E-865NT as a tackifier resin [Arakawa Chemical Industries, Ltd .; softening point 160 ° C., solid content concentration 50% by mass , Emulsion type polymerized rosin ester tackifying resin] 100 g, Tamanol E-200NT [manufactured by Arakawa Chemical Industries, Ltd .; softening point 150 ° C., solid content concentration 53 mass%, emulsion type rosin phenol type tackifying resin] 94.34 g Add water and disperse acrylic adhesive by filtering through 200 mesh wire mesh Composition (1) was obtained.

(Preparation Example 2) Preparation of Water Dispersible Acrylic Adhesive Composition (2) Emulsified in the same manner as in Example 1 except that the amount of lauryl mercaptan used was changed from 0.2 g to 0.3 g (2) was prepared.

A water-dispersible acrylic adhesive containing an acrylic polymer emulsion (2) in the same manner as in Preparation Example 1, except that the emulsion (2) was used instead of the emulsion (1). An agent composition (2) was obtained. The average particle diameter of the acrylic polymer contained in the water-dispersible acrylic pressure-sensitive adhesive composition (2) was 330 nm. The weight average molecular weight of the acrylic polymer contained in the acrylic polymer emulsion (1) was 500,000.

(Preparation Example 3)
In a container, 75 g of ion-exchange water and Aqualon KH-1025 as a surfactant (Daiichi Kogyo Seiyaku Co., Ltd .; active ingredient 25% by mass) and Latemul PD-104 as a surfactant (Kao Co., Ltd.); Active ingredient 20% by mass] 37.5 g was added and dissolved uniformly. Thereto, 227.5 g of n-butyl acrylate, 227.5 g of 2-ethylhexyl acrylate, 25 g of methyl methacrylate, 7.5 g of N-vinylpyrrolidone, 12.5 g of acrylic acid and 0.2 g of lauryl mercaptan were added to emulsify, and the emulsion (3) 635.83 g was obtained.

An acrylic polymer emulsion (3) was prepared in the same manner as in Preparation Example 1, except that the emulsion (3) was used instead of the emulsion (1). Subsequently, 1000 g of the acrylic polymer emulsion (3) was added to Surfinol PSA-336 [manufactured by Air Products Japan Co., Ltd .; active ingredient 100% by mass] as a leveling agent, and Surfinol as an antifoaming agent. DF-110D [manufactured by Air Products Japan, Inc .; active ingredient 100% by mass] 2.5 g, superester E-865NT as a tackifier resin [manufactured by Arakawa Chemical Industries, Ltd .; softening point 160 ° C., solid content concentration 50% by mass, emulsion-type polymerized rosin ester-based tackifier resin] 50 g, Tamanol E-200NT [manufactured by Arakawa Chemical Industries, Ltd .; softening point 150 ° C., solid content concentration 53% by mass, emulsion-type rosin phenol-based tackifier resin] Add 141.51g and filter with 200 mesh wire mesh to disperse water dispersible acrylic Was obtained adhesive composition (3). The average particle diameter of the acrylic polymer contained in the water-dispersible acrylic pressure-sensitive adhesive composition (3) was 338 nm. The weight average molecular weight of the acrylic polymer contained in the acrylic polymer emulsion (1) was 740,000.

(Preparation Example 4)
Preparation Example 1 except that the compounding amount of the tackifying resin superester E-865NT was changed from 100 g to 200 g and the compounding amount of the tackifying resin Tamanol E-200NT was changed from 94.34 g to 0 g. A water-dispersed acrylic pressure-sensitive adhesive composition (4) was prepared in the same manner.

(Preparation Example 5)
Preparation Example, except that the amount of the tackifier resin superester E-865NT was changed from 100 g to 0 g, and the amount of the tackifier resin Tamanol E-200NT was changed from 94.34 g to 188.68 g 1 was used to prepare a water-dispersed acrylic pressure-sensitive adhesive composition (5).

In Table 1, “BA” represents n-butyl acrylate, “2EHA” represents 2-ethylhexyl acrylate, “MMA” represents methyl methacrylate, “NVP” represents n-vinylpyrrolidone, and “AA” represents Acrylic acid is represented, "MAA" represents methacrylic acid, and "L-SH" represents lauryl mercaptan.

(Example 1)
Two liquids were prepared by mixing 1000 g of the water-dispersible acrylic pressure-sensitive adhesive composition (1) and 1.0 g of a 10 mass% ethanol solution of Tetrad C [manufactured by Mitsubishi Gas Chemical Co., Ltd., epoxy compound] as a crosslinking agent. A cross-linked water-dispersible acrylic pressure-sensitive adhesive (1) was obtained.

Immediately after preparing the two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive (1), it was applied onto a 75 μm-thick polyester film that had been subjected to a release treatment so that the thickness after drying was 47 μm. Two laminates were produced by drying at 5 ° C. for 5 minutes. The pressure-sensitive adhesive layer constituting the laminate was laminated on both surfaces of the nonwoven fabric substrate (x1), and then laminated at a pressure of 4 kgf / cm using a hot roll adjusted to 90 ° C. The laminated product was cured for 3 days in an environment of 40 ° C. to obtain an adhesive tape (1). The obtained adhesive tape had a thickness of 100 μm.

(Example 2)
Instead of the water-dispersible acrylic pressure-sensitive adhesive composition (1), the water-dispersible acrylic pressure-sensitive adhesive composition (2) obtained in Preparation Example 2 was used, and Tetrad C [Mitsubishi Gas Chemical Co., Ltd.] A pressure-sensitive adhesive tape (2) was produced in the same manner as in Example 1 except that the amount of the 10 mass% ethanol solution of the epoxy product] was changed from 1.0 g to 1.5 g. The obtained adhesive tape had a thickness of 100 μm.

(Example 3)
An adhesive tape (3) was obtained in the same manner as in Example 1 except that the thickness after drying was changed from 47 μm to 42 μm. The obtained adhesive tape had a thickness of 90 μm.

Example 4
An adhesive tape (4) in the same manner as in Example 1 except that the nonwoven fabric substrate (x2) was used instead of the nonwoven fabric substrate (x1) except that the nonwoven fabric substrate (x2) was used. ) The obtained adhesive tape had a thickness of 100 μm.

(Example 5)
An adhesive tape (5) was obtained in the same manner as in Example 1 except that the thickness after drying was changed from 47 μm to 37 μm. The obtained adhesive tape had a thickness of 80 μm.

(Example 6)
An adhesive tape (6) was obtained in the same manner as in Example 2 except that the thickness after drying was changed from 47 μm to 37 μm. The obtained adhesive tape had a thickness of 80 μm.

(Example 7)
Instead of the water-dispersible acrylic pressure-sensitive adhesive composition (1), the water-dispersible acrylic pressure-sensitive adhesive composition (3) obtained in Preparation Example 3 was used, and Tetrad C [Mitsubishi Gas Chemical Co., Ltd.] The adhesive tape (7) was produced by the same method as Example 1 except having changed the usage-amount of the 10 mass% ethanol solution of an epoxy compound] from 1.0 g to 1.25 g. The thickness of the obtained adhesive tape was 100 μm.

(Example 8)
An adhesive tape (10) was obtained in the same manner as in Example 7 except that the thickness after drying was changed from 47 μm to 37 μm. The obtained adhesive tape had a thickness of 80 μm.

Example 9
In the same manner as in Example 1, except that the water-dispersible acrylic pressure-sensitive adhesive composition (4) obtained in Preparation Example 4 was used instead of the water-dispersible acrylic pressure-sensitive adhesive composition (1). An adhesive tape (12) was obtained. The obtained adhesive tape had a thickness of 100 μm.

(Example 10)
In the same manner as in Example 1, except that the water-dispersible acrylic pressure-sensitive adhesive composition (5) obtained in Preparation Example 5 was used instead of the water-dispersible acrylic pressure-sensitive adhesive composition (1). An adhesive tape (13) was obtained. The obtained adhesive tape had a thickness of 100 μm.

(Comparative Preparation Example 1) Preparation of 1-component water-dispersible acrylic pressure-sensitive adhesive composition (H1) In a container, 75 g of ion exchange water and Aqualon KH-1025 as a surfactant [Daiichi Kogyo Seiyaku Co., Ltd .; effective Ingredients 25% by mass] 20 g and surfactant LATEMUL PD-104 [manufactured by Kao Corporation; active ingredient 20% by mass] 37.5 g were added and dissolved uniformly. Thereto, 227.5 g of n-butyl acrylate, 227.5 g of 2-ethylhexyl acrylate, 25 g of methyl methacrylate, 7.5 g of N-vinylpyrrolidone, 12.5 g of acrylic acid and 0.2 g of lauryl mercaptan were added to emulsify, and the emulsion 635.83 g of (H1) was obtained.

A water-dispersible acrylic adhesive containing an acrylic polymer emulsion (H1) in the same manner as in Example 1 except that the emulsion (H1) was used instead of the emulsion (1). An agent composition was obtained. The average particle diameter of the acrylic polymer was 338 nm.

To the water-dispersible acrylic pressure-sensitive adhesive composition 1000 g, Surfynol PSA-336 [Air Products Japan Co., Ltd .; active ingredient 100% by mass] 2.5 g as a leveling agent, Surfynol DF- as an antifoaming agent 110D [manufactured by Air Products Japan Co., Ltd .; active ingredient 100% by mass] 2.5 g, superester E-865NT [made by Arakawa Chemical Co., Ltd. as tackifier resin; softening point 160 ° C., solid content concentration 50 mass %, Emulsion-type polymerized rosin ester-based tackifier resin] 100 g, Tamanol E-200NT [Arakawa Chemical Industries, Ltd .; softening point 150 ° C., solid content concentration 53 mass%, emulsion-type rosin phenol-based tackifier resin] 94. 34 g was added, filtered through a 200 mesh wire mesh, Tetrad C [Mitsubishi Gas Chemical Co., Ltd., Epoch 1.5 g of a 10 mass% ethanol solution of the succinic compound] was added and allowed to stand at 23 ° C. for 1 week, and the acrylic polymer and the epoxy compound were reacted to form a one-part water-dispersible acrylic system. An adhesive (H1) was obtained.

The one-component water-dispersible acrylic pressure-sensitive adhesive (H1) immediately after the production was applied on a 75 μm-thick polyester film whose mass (G0) was measured in advance so that the thickness after drying was 47 μm. A laminate of the pressure-sensitive adhesive layer and the polyester film obtained by drying at 100 ° C. for 5 minutes was cut into a size of 40 mm × 50 mm, and the mass (G1) was measured.

The sample was immersed in a toluene solution at 25 ° C. (normal temperature) for 24 hours. The toluene-insoluble matter of the sample after immersion was separated by filtering through a 300 mesh wire mesh, and the mass (G2) of the residue after drying at 105 ° C. for 1 hour was measured. It was 48 mass% when the fraction was computed. Gel fraction (mass%) = [(G2-G0) / (G1-G0)] × 100

(Comparative Preparation Example 2)
A one-component water-dispersible acrylic pressure-sensitive adhesive composition (H2) was prepared in the same manner as in Comparative Preparation Example 1 except that the emulsion (1) was used instead of the emulsion (H1). . The initial gel fraction of the obtained one-component water-dispersible acrylic pressure-sensitive adhesive composition (H2) was measured by the same method as described in Comparative Preparation Example 1 and found to be 36% by mass.

(Comparative Preparation Example 3)
Comparative Preparation Example, except that the temperature (polymerization temperature) in the reaction vessel was changed from 60 ° C. to 80 ° C., and the blending amount of the tetrad C 10 mass% ethanol solution was changed from 1.5 g to 0.5 g. In the same manner as in Example 1, a one-component water-dispersed acrylic pressure-sensitive adhesive composition (H3) was prepared. The initial gel fraction of the obtained one-component water-dispersed acrylic pressure-sensitive adhesive composition (H3) was measured by the same method as described in Comparative Preparation Example 1 and found to be 41% by mass.

(Comparative Preparation Example 4)
In the same manner as in Example 1, except that the emulsion (H1) was used instead of the emulsion (1) and the temperature (polymerization temperature) in the reaction vessel was changed from 60 ° C to 80 ° C. A water-dispersed acrylic pressure-sensitive adhesive composition was prepared. The initial gel fraction of the obtained water-dispersed acrylic pressure-sensitive adhesive composition was measured by the same method as described in Comparative Preparation Example 1 and found to be 28% by mass.

In Table 2, “BA” represents n-butyl acrylate, “2EHA” represents 2-ethylhexyl acrylate, “MMA” represents methyl methacrylate, “NVP” represents n-vinylpyrrolidone, and “AA” represents Acrylic acid is represented, "MAA" represents methacrylic acid, and "L-SH" represents lauryl mercaptan.

(Comparative Example 1)
The one-component water-dispersible acrylic pressure-sensitive adhesive (H1) is coated on a 75 μm-thick polyester film having been subjected to a release treatment so that the thickness after drying is 47 μm, and dried at 100 ° C. for 5 minutes. Thus, two laminates were produced. The pressure-sensitive adhesive layer constituting the laminate is laminated on both sides of the nonwoven fabric substrate (x1), and then laminated at a pressure of 4 kgf / cm using a hot roll adjusted to 90 ° C., thereby producing a pressure-sensitive adhesive tape (H1). Got.

(Comparative Example 2)
A pressure-sensitive adhesive tape (in the same manner as in Example 1 except that a one-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive (H2) is used instead of the one-component water-dispersible acrylic pressure-sensitive adhesive (H1). H2) was obtained.

(Comparative Example 3)
An adhesive tape (H3) was obtained in the same manner as in Comparative Example 1 except that the thickness after drying was changed from 47 μm to 42 μm. The obtained adhesive tape had a thickness of 90 μm.

(Comparative Example 4)
An adhesive tape (H4) was obtained in the same manner as in Comparative Example 2 except that the thickness after drying was changed from 47 μm to 42 μm. The obtained adhesive tape had a thickness of 90 μm.

(Comparative Example 5)
A pressure-sensitive adhesive tape (H5) was obtained in the same manner as in Comparative Example 1 except that the one-component water-dispersed acrylic pressure-sensitive adhesive composition (H3) prepared in Comparative Preparation Example 3 was used. The obtained adhesive tape had a thickness of 100 μm.

(Comparative Example 6)
A pressure-sensitive adhesive tape (H6) was obtained in the same manner as in Comparative Example 1 except that the water-dispersed acrylic pressure-sensitive adhesive composition prepared in Comparative Example 4 was used. The obtained adhesive tape had a thickness of 100 μm.

(Reference Example 1)
An adhesive tape (S1) was obtained in the same manner as in Comparative Example 2 except that the thickness after drying was changed from 47 μm to 65 μm. The obtained adhesive tape had a thickness of 140 μm.

[Evaluation methods]
(Measurement of gel fraction immediately after the drying process)
Prior to the production of the adhesive tapes of Examples and Comparative Examples, the masses (G0) of the nonwoven fabric substrates (x1) and (x2) were measured.

Next, the material immediately after the pressure-sensitive adhesive layer was transferred to the nonwoven fabric substrate (x1) or (x2) was cut into a size of 40 mm × 50 mm, and the mass (G1) was measured.

The sample was immersed in a toluene solution at 25 ° C. (normal temperature) for 24 hours. The toluene insoluble matter of the sample after immersion was separated by filtering through a 300 mesh wire net, and the mass (G2) of the residue after drying at 105 ° C. for 1 hour was measured. The gel fraction was calculated according to the following formula. Gel fraction (mass%) = [(G2-G0) / (G1-G0)] × 100

(Measurement of gel fraction of adhesive layer of adhesive tape)
Prior to the production of the adhesive tapes of Examples and Comparative Examples, the masses (G0) of the nonwoven fabric substrates (x1) and (x2) were measured.

Next, the adhesive tape produced by the method described in Examples and Comparative Examples was cut into a size of 40 mm × 50 mm, and the mass (G1) was measured.

The sample was immersed in a toluene solution at 25 ° C. (normal temperature) for 24 hours. The toluene insoluble matter of the sample after immersion was separated by filtering through a 300 mesh wire mesh, and the mass (G3) of the residue after drying at 105 ° C. for 1 hour was measured. The gel fraction was calculated according to the following formula. Gel fraction (mass%) = [(G3-G0) / (G1-G0)] × 100

[Evaluation method of constant load holding force]
One side of the double-sided pressure-sensitive adhesive tapes obtained in Examples and Comparative Examples was lined with a polyethylene terephthalate film having a thickness of 25 μm, and cut into a width of 10 mm and a length of 70 mm to prepare a test tape.

A range of 50 mm in length of the test tape was attached to a stainless steel plate, and reciprocated using a 2 kg roller to adhere them.

The bonded material is left in an atmosphere of 23 ° C. and 50% RH for 1 hour, then a load of 300 g is applied in the direction of 90 ° to the peeling direction, and the time until the test tape falls is measured. Evaluation was made according to the following criteria. The constant load holding force evaluation method described above is a substitute evaluation method assuming that deformation stress is applied to the test tape from the outside for a long time. The longer the time until dropping, the better the constant load holding force. It was judged that the level held for longer than 3 hours was a practically acceptable level. The value in the table represents the time [unit: minute] until the drop.

◎: It did not fall after 4 hours (240 minutes).

○: It fell for 3 hours or more and less than 4 hours (180 minutes or more and less than 240 minutes).

△: It fell for 2 hours or more and less than 3 hours (120 minutes or more and less than 180 minutes).

X: Dropped in less than 2 hours.

[Evaluation Method for Adhesiveness (180 Degree Peel Adhesive Strength)]
In the measurement based on JIS-Z-0237,
One side of the double-sided pressure-sensitive adhesive tapes obtained in Examples and Comparative Examples was lined with a polyethylene terephthalate film having a thickness of 25 μm and cut into a size of 20 mm width × 100 mm length to obtain a backed pressure-sensitive adhesive tape.

The backed adhesive tape was stuck on the surface of a stainless steel plate under a 23 ° C / 50% environment with a 2 kg roller, and left for 1 hour in a 23 ° C / 50% environment. A test tape was obtained. The adhesive strength when the test tape was peeled off at a speed of 300 m / min in the 180 degree direction was measured.

[Evaluation method of removability]
One side of the double-sided pressure-sensitive adhesive tapes obtained in Examples and Comparative Examples was lined with a PET film having a thickness of 25 μm and cut into a size of 20 mm width × 100 mm length to obtain a backed pressure-sensitive adhesive tape.

The backed pressure-sensitive adhesive tape was applied to the surface of a polymer alloy plate (polycarbonate resin and acrylonitrile-butadiene-styrene resin) under a temperature of 23 ° C. and a relative humidity of 50% by one reciprocating pressure with a 2 kg roller, The test tape was left for 1 hour in an environment of a temperature of 60 ° C. and a relative humidity of 90%. The removability when the test tape was peeled off at a speed of 25 m / min in the direction of 135 degrees was measured.
The evaluation of removability was performed according to the following criteria.

◎: The adhesive residue on the adherend and the remaining area of the adhesive tape due to the cutting of the nonwoven fabric are less than 1% of the pasting area.

◯: The adhesive residue on the adherend and the remaining area of the adhesive tape due to the cutting of the nonwoven fabric are 1% or more and less than 10% of the sticking area.

Δ: The adhesive residue on the adherend and the remaining area of the adhesive tape by cutting the nonwoven fabric are 10% or more and less than 50% of the pasting area.

X: The adhesive residue on the adherend and the remaining area of the adhesive tape by cutting the nonwoven fabric are 50% or more of the pasting area.

Claims

A pressure-sensitive adhesive layer having a total thickness of 120 μm or less, wherein the pressure-sensitive adhesive tape is formed using a two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive containing an acrylic polymer and a crosslinking agent. A pressure-sensitive adhesive tape comprising:
The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer has a crosslinked structure, and the gel fraction of the pressure-sensitive adhesive layer is in the range of 30% by mass to 60% by mass.
The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer is provided on one side or both sides of a substrate.
The pressure-sensitive adhesive tape according to claim 3, wherein the substrate is a nonwoven fabric substrate.
The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 60 μm or less.
The pressure-sensitive adhesive tape according to claim 1, wherein the acrylic polymer has a weight average molecular weight of 300,000 to 1,200,000.
The acrylic polymer is obtained by polymerizing a monomer containing an alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms and a (meth) acrylic monomer having a carboxyl group. The pressure-sensitive adhesive tape according to claim 1.
The pressure-sensitive adhesive tape according to claim 7, wherein the (meth) acrylic monomer having a carboxyl group contains acrylic acid and methacrylic acid.
The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer contains a tackifying resin containing at least one selected from the group consisting of a polymerized rosin ester-based tackifying resin and a rosin phenol-based tackifying resin.
A method for producing a pressure-sensitive adhesive tape having a total thickness of 120 μm or less, wherein a gel fraction obtained by mixing a water-dispersed acrylic pressure-sensitive adhesive composition containing an acrylic polymer and a crosslinking agent is 15% by mass A pressure-sensitive adhesive layer having a gel fraction of 30% by mass or more is formed by applying or impregnating the following two-component cross-linkable water-dispersible acrylic pressure-sensitive adhesive to a substrate and drying to form a crosslinked structure. The manufacturing method of the adhesive tape characterized by the above-mentioned.