WO2011125918A1

WO2011125918A1 - Adhesive sheet

Info

Publication number: WO2011125918A1
Application number: PCT/JP2011/058372
Authority: WO
Inventors: 智諭富能; 弘晃岩渕; 井上　誠
Original assignee: リンテック株式会社
Priority date: 2010-03-31
Filing date: 2011-03-25
Publication date: 2011-10-13
Also published as: CN102822293B; CN102822293A; JP5925676B2; MY174479A; JPWO2011125918A1

Abstract

Disclosed is an adhesive sheet comprising a front base material and an adhesive layer provided on the back surface of the front base material, said adhesive sheet being characterized in that the adhesive layer is formed by applying an aqueous dispersion adhesive prepared by adding, as a plasticizer, a nonionic surfactant containing an amino group to an aqueous dispersion adhesive composition that contains 2-ethylhexyl acrylate, ethylenically unsaturated carboxylic acid and, as necessary, an acrylic copolymer obtained by emulsion polymerization of other polymerizable unsaturated monomers. The adhesive sheet has superior adherence between the front base material and adhesive layer, and the adhesion to adherends is superior. Furthermore, the adhesive sheet does not leave an adhesive residue on the adherend, even when peeled off after being adhered for a long period of time.

Description

Adhesive sheet

The present invention relates to a pressure-sensitive adhesive sheet, and more particularly, to a re-peelable pressure-sensitive adhesive sheet that can be peeled off after being attached to a resin casing of home appliances and electronic devices, and can be recycled while being attached to the casing as needed.

2. Description of the Related Art Conventionally, an adhesive sheet having a product name, a product description, a usage method, and the like attached to a resin casing of a home appliance or an electronic device is attached to the surface and displayed and sold.
In recent years, from the viewpoint of resource saving, recycling is performed by collecting, crushing, and reusing used plastic housings of home appliances and electronic devices.
When recycling resin housings for home appliances and electronic devices, if the adhesive sheet is affixed to the resin housing, the adhesive sheet may be peeled off for recycling or recycled with the adhesive sheet still attached. Sometimes.
When the adhesive sheet is peeled off from the resin casing and recycled, a sufficient adhesive force is required to be firmly fixed while being attached to the resin casing, and when peeling from the resin casing, The releasability that can be easily peeled is also required for the pressure-sensitive adhesive sheet. Moreover, when recycling with the adhesive sheet attached to the resin casing, it is required that the surface base material of the adhesive sheet and the material of the resin casing are the same.
That is, the pressure-sensitive adhesive sheet is required to have an adhesive force to an adherend such as a resin casing and a removability from the adherend, and is a surface substrate made of the same material as the adherend. It is required and desired to meet these requirements.
On the other hand, the pressure-sensitive adhesive for the releasable pressure-sensitive adhesive sheet has shifted from a solvent-based pressure-sensitive adhesive to a water-based pressure-sensitive adhesive from the viewpoint of environmental problems. In the case of the water-based pressure-sensitive adhesive, when the peelability from the adherend is facilitated, there is a problem that the adhesive force with the surface base material, which is the same material, is reduced, and the pressure-sensitive adhesive layer remains on the adherend.
Conventionally, it has good adhesion to adherends such as paper, metal and plastics, and the adhesive component does not remain on the adherend when the adhesive label is peeled off from the adherend. As an adhesive sheet intended to be peelable, an aqueous adhesive composition containing adhesive fine particles (A) and, if necessary, a binder (B) on the surface of a surface substrate, polyoxyethylene as a plasticizer A pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive composition layer to which a surfactant-based plasticizer such as nonylphenyl ether is added has been proposed (see Japanese Patent Application Laid-Open No. 2000-281989).
In Patent Document 1, as a surfactant-based plasticizer, only polyoxyethylene nonylphenyl ether is used in the examples, and other specific examples include polyoxyethylene lauryl ether, polyoxyethylene lauryl ether in paragraph [0058]. Polyoxyalkylene alkyl or alkenyl ethers such as oxyethylene stearyl ether, polyoxyethylene di (stearyl) ether, polyoxyethylene octyl phenyl ether, polyoxyethylene di (nonyl) phenyl ether, polyoxyethylene di (nonylphenyl) ether Only polyoxyalkylphenyl ethers are described.
However, the pressure-sensitive adhesive sheet using a pressure-sensitive adhesive containing these surfactant plasticizers does not have sufficient adhesive strength between the surface base material and the pressure-sensitive adhesive layer when peeled from the adherend, and the pressure-sensitive adhesive component is not covered. There is a problem in that adhesive residue remaining on the adherend may occur, and re-peelability is not always sufficient.

The present invention has been made in view of the above-described prior art. The surface base material and the pressure-sensitive adhesive layer have excellent adhesion, and are excellent in adhesion to an adherend. It is an object of the present invention to provide an adhesive sheet that does not cause adhesive residue on an adherend even if it is peeled off after being applied to the adherend for a long time.
In order to solve the above problems, the present inventors prepared by adding an amino group-containing nonionic surfactant as a plasticizer to a water-dispersed adhesive composition containing a specific acrylic copolymer. It has been found that the above problem can be solved by providing a pressure-sensitive adhesive layer obtained by applying a water-dispersed pressure-sensitive adhesive on the back surface of the surface base material, and the present invention has been completed based on this finding.
That is, the present invention is a pressure-sensitive adhesive sheet comprising a surface base material and a pressure-sensitive adhesive layer provided on the back surface of the surface base material, wherein the pressure-sensitive adhesive layer contains 2-ethylhexyl acrylate and ethylenically unsaturated carboxylic acid. A water-dispersed pressure-sensitive adhesive prepared by adding an amino group-containing nonionic surfactant as a plasticizer to a water-dispersed pressure-sensitive adhesive composition containing an acrylic copolymer obtained by emulsion polymerization is applied. The present invention provides a pressure-sensitive adhesive sheet that is formed.
Moreover, this invention provides the adhesive sheet in which the surface base material is comprised with the raw material same as the material of the adherend which affixes an adhesive sheet in the said adhesive sheet.
Moreover, this invention provides the adhesive sheet in which the surface base material is comprised with the polystyrene resin, the acrylonitrile-butadiene-styrene copolymer resin, the polycarbonate resin, or the mixture of 2 or more types of the said resin in the said adhesive sheet. Is.
In the pressure-sensitive adhesive sheet according to the present invention, the acrylic copolymer is obtained by emulsion polymerization of 2-ethylhexyl acrylate, ethylenically unsaturated carboxylic acid, and, if necessary, other unsaturated monomers copolymerizable. An adhesive sheet which is an acrylic copolymer obtained in this way is provided.
The pressure-sensitive adhesive sheet of the present invention has excellent adhesion between the surface base material and the pressure-sensitive adhesive layer, and also has excellent adhesion to the adherend, and may be peeled off after being applied to the adherend for a long time. There is no adhesive residue on the adherend.

The water-dispersed pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer in the present invention is a water-dispersed pressure-sensitive adhesive containing an acrylic copolymer obtained by emulsion polymerization of 2-ethylhexyl acrylate and ethylenically unsaturated carboxylic acid. The composition was prepared by adding an amino group-containing nonionic surfactant as a plasticizer.
The acrylic copolymer may be one obtained by copolymerizing monomers consisting essentially of 2-ethylhexyl acrylate and ethylenically unsaturated carboxylic acid, and can be copolymerized with these monomers. It is also possible to copolymerize other unsaturated monomers. Preferably, it is a copolymer of monomers consisting essentially of 2-ethylhexyl acrylate and an ethylenically unsaturated carboxylic acid.
Examples of the ethylenically unsaturated carboxylic acid include (meth) acrylic acid such as acrylic acid and methacrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, and fumaric anhydride, and preferably (meth) acrylic acid. It is. An ethylenically unsaturated carboxylic acid may be used individually by 1 type, and may be used in combination of 2 or more type. The ethylenically unsaturated carboxylic acid is particularly preferably a combination of acrylic acid and methacrylic acid. When acrylic acid and methacrylic acid are used in combination, the polymerization ratio of both is preferably 1/10 to 10/1, more preferably 1/5 to 5/1, and still more preferably 1/3 to 3/1.
Other unsaturated monomers include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, (Meth) acrylic acid alkyl ester having 1 to 20 carbon atoms, such as hexyl methacrylate and lauryl methacrylate, -2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, -3-hydroxypropyl acrylate 3-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 3-hydroxybutyl methacrylate, methacrylate Examples include hydroxyl group-containing (meth) acrylic acid alkyl esters such as 4-hydroxybutyl laurate. Another unsaturated monomer may be used individually by 1 type, and may be used in combination of 2 or more type.
The content ratio of the units derived from the ethylenically unsaturated carboxylic acid in the acrylic copolymer is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the unit derived from 2-ethylhexyl acrylate. 3 to 5 parts by mass is more preferable. The content ratio of units derived from other unsaturated monomers in the acrylic copolymer is preferably 0 to 20 parts by mass with respect to 100 parts by mass of units derived from 2-ethylhexyl acrylate. ~ 15 parts by mass is more preferred.
In the present invention, the acrylic copolymer is obtained by emulsion polymerization. Emulsion polymerization can be performed by various emulsion polymerization methods, but may be a general emulsion polymerization method. Specifically, for example, 2-ethylhexyl acrylate and ethylenically unsaturated carboxylic acid, and other monomers such as an unsaturated monomer, an emulsifier, a polymerization initiator, etc. are charged into the reactor as necessary. Then, after substituting the inside with an inert gas such as nitrogen, the temperature is raised with stirring using water as a dispersion medium under reflux, and an appropriate polymerization temperature, for example, within a temperature range of about 40 to 100 ° C. A method of carrying out emulsion polymerization for about 1 to 8 hours, for example, is mentioned.
The emulsifier used at the time of emulsion polymerization is not particularly limited, and examples thereof include an anionic emulsifier, a nonionic emulsifier, and a reactive emulsifier. However, the emulsifier used at the time of emulsion polymerization is different from the amino group-containing nonionic surfactant as a plasticizer added after the emulsion polymerization.
Examples of the anionic emulsifier include potassium oleate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl allyl ether sulfate, Examples include ammonium polyoxyethylene alkyl allyl ether sulfate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl allyl ether phosphate, and the like.
Examples of the nonionic emulsifier include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oxypropylene block copolymer, polyethylene glycol fatty acid ester, polypropylene glycol cresol ether, polyoxyethylene sorbitan fatty acid ester and the like.
Examples of reactive emulsifiers include polyethylene glycol mono (meth) acrylate, polyoxyethylene alkylphenol ether (meth) acrylate and ammonium 2- (meth) acryloyloxyethylsulfonate having various molecular weights (different number of moles of ethylene oxide added). And monomaleic acid ester of polyoxyethylene glycol and derivatives thereof, (meth) acryloyl polyoxyalkylene alkyl ether phosphate, and the like. Among the above, preferred emulsifiers from the viewpoint of environmental hygiene, particularly those that do not cause environmental hormone problems, are higher alcohol derivatives.
An emulsifier can also be used individually by 1 type and can also be used in combination of 2 or more type.
The amount of the emulsifier used is usually preferably 0.2 to 10 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the acrylic copolymer. When the amount of the emulsifier is in the above range, an emulsion having an appropriate particle size can be obtained without producing a coagulated product.
The acrylic copolymer obtained by emulsion polymerization is obtained in the form of an emulsion. The average particle size of the acrylic copolymer dispersed in the emulsion is preferably 100 to 500 nm, more preferably 150 to 400 nm, and still more preferably 200 to 350 nm.
The weight average molecular weight of the acrylic copolymer is preferably 30,000 to 1,500,000, more preferably 50,000 to 1,000,000, and particularly preferably 100,000 to 500,000. In addition, in this specification, a weight average molecular weight is the value of standard polystyrene conversion which measured the tetrahydrofuran soluble component by the gel permeation chromatography method.
In the present invention, a water-dispersed pressure-sensitive adhesive composition containing an acrylic copolymer is obtained by the emulsion polymerization.
The water-dispersed pressure-sensitive adhesive in the present invention is obtained by adding an amino group-containing nonionic surfactant as a plasticizer to the water-dispersed pressure-sensitive adhesive composition containing the acrylic copolymer and mixing them. .
As the amino group-containing nonionic surfactant, various types can be used as long as the amino group is bonded to the nonionic surfactant. The number of amino groups is one molecule of the nonionic surfactant. Among them, 6 or less are preferable, 3 or less are preferable, and 2 or less are particularly preferable.
Preferable specific examples of the amino group-containing nonionic surfactant include polyoxyalkyleneamine, and polyoxyalkylenealkylamine is more preferable. Specific examples of the polyoxyalkylene amine include, for example, a polyoxyalkylene amine represented by the formula (1).

(In the formula, R is an alkyl group, alkenyl group or acyl group having 3 to 30 carbon atoms, A ¹ and A ² are alkylene groups having 2 to 4 carbon atoms, and x and y are 0 or a positive integer. Yes, x + y is 2 to 40. When x is 2 or more, the plurality of A ¹ may be the same or different, and when y is 2 or more, the plurality of A ² are the same. May be different or different.)
The carbon number of R in the formula (1) is preferably 4 to 24, more preferably 6 to 20, and particularly preferably 10 to 20. A ¹ and A ² include an ethylene group, a propylene group, and a butylene group, but an ethylene group and a propylene group are preferable, and an ethylene group is more preferable. When x and y are 2 or more, (A ¹ O) x and (A ² O) y are one kind of oxyalkylene group such as polyoxyethylene group, polyoxypropylene group, polyoxybutylene group and the like. It may be a chain or a polyoxyalkylene group composed of a combination of two or more oxyalkylene groups having 2 to 4 carbon atoms. The polyoxyalkylene group composed of a combination of two or more oxyalkylene groups having 2 to 4 carbon atoms may have a random structure or a block structure. X + y is 2 to 40, preferably 3 to 20, and particularly preferably 4 to 17.
The amino group-containing nonionic surfactant preferably has an HLB value of 8 to 20, particularly preferably 10 to 16.
One type of amino group-containing nonionic surfactant may be used, or two or more types may be used in combination. When combining 2 or more types, it is particularly preferable to combine 2 or more of the above-mentioned particularly preferable types.
The addition amount of the amino group-containing nonionic surfactant as the plasticizer is preferably 0.1 to 2.0 parts by mass, and 0.15 to 1.5 parts by mass with respect to 100 parts by mass of the acrylic copolymer. Is more preferable, and 0.2 to 1.2 parts by mass is even more preferable.
The water-dispersed pressure-sensitive adhesive of the present invention preferably contains a crosslinking agent in order to crosslink the acrylic copolymer with a crosslinking agent.
As the crosslinking agent used for crosslinking the acrylic copolymer, an epoxy crosslinking agent is preferable. Examples of the epoxy-based crosslinking agent include neopentyl glycol diglycidyl ether, polyethylene glycol diglycidyl ether, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, phthalic acid diglycidyl ester, dimer acid diglycidyl ether, and triglycidyl isocyanurate. , Diglycerol triglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol tetraglycidyl ether, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylamino) Epoxy crosslinking agents such as methyl) cyclohexane and N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane are used.
A crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the crosslinking agent used is preferably 0.01 to 10 parts by mass and more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the acrylic copolymer.
Various additives, such as a thickener, a tackifier, and a stabilizer, can be mix | blended with the water dispersion-type adhesive of this invention.
Examples of the thickener include polyacrylic acid polymers, polymethacrylic acid polymers, poly (meth) acrylic acid ester polymers, polyolefin polymers, and the like. The blending ratio of the thickener may be an amount that can be adjusted to an appropriate viscosity for applying the viscosity of the water-dispersed pressure-sensitive adhesive, and the viscosity of the water-dispersed pressure-sensitive adhesive is 100 to 10,000 mPa · s (BM type viscometer, The amount may be in a range of 25 ° C. and 60 rpm. Usually, 0.1 to 10 parts by mass is preferable and 1 to 5 parts by mass is more preferable with respect to 100 parts by mass of the acrylic copolymer.
Examples of the tackifier include rosin ester tackifiers such as rosin, rosin ester and hydrogenated rosin ester, and terpene tackifiers such as terpene phenol resin. The tackifier may be allowed to coexist with an acrylic monomer during emulsion polymerization, a tackifier resin emulsion emulsified by a known method may be added after emulsion polymerization, or both may be used in combination. Good. The blending ratio of the tackifier is usually preferably 0.1 to 20 parts by mass and more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the acrylic copolymer. By making the blending ratio of the tackifier 0.1 parts by mass or more, it can be used without peeling during sticking, and by making the blending ratio of the tackifier 20 parts by mass or less, there is no adhesive residue from the adherend. Can be easily peeled off.
In the water-dispersed pressure-sensitive adhesive composition of the present invention, the resin solid content is usually 30 to 70% by mass, and preferably 40 to 60% by mass.
The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet including a surface base material and a pressure-sensitive adhesive layer provided on the back surface of the surface base material.
As the surface substrate, various plastic sheets and films can be used. Specific examples of the surface substrate include, for example, polyolefin resins such as polyethylene resin and polypropylene resin, polyester resins such as polyethylene terephthalate resin, polyethylene naphthalate resin and polybutylene terephthalate resin, polyvinyl chloride resin, polystyrene resin, acrylonitrile-butadiene- Examples include sheets and films of various synthetic resins such as styrene copolymer resins (ABS resins), polycarbonate resins, polyamide resins, polyimide resins, fluorine resins, and mixtures of two or more of these, and particularly high strength. Since it is inexpensive, it is preferable to use the same material as the resin material used in the resin casing of home appliances and electronic devices. As these surface base materials, a sheet or film composed of polystyrene resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polycarbonate resin, or a mixture of two or more of the above resins is preferable. The surface substrate may be a single layer, or may be a multilayer of two or more layers of the same type or different types.
The thickness of the surface substrate is not particularly limited, but is usually preferably 10 to 350 μm, more preferably 15 to 300 μm, and particularly preferably 20 to 250 μm.
A print receiving layer may be provided on the surface of the surface substrate. When a print receiving layer is provided on the surface of the surface substrate, printing can be performed after the pressure-sensitive adhesive layer is provided on the back surface of the surface substrate.
The print receiving layer can be provided by applying various printing coating agents. As the printing coating agent, an acrylic resin or a polyester resin, or a printing coating agent using them in combination is preferably used.
The back surface of the surface base material may be subjected to an easy adhesion treatment in order to further increase the adhesion with the pressure-sensitive adhesive layer. Although there is no restriction | limiting in particular as an easily bonding process, For example, a corona discharge process etc. are mentioned.
In the pressure-sensitive adhesive sheet of the present invention, a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition is formed on the back surface of the surface base material.
The thickness of the pressure-sensitive adhesive layer is not particularly limited, but the film thickness after drying is usually preferably 3 to 150 μm, more preferably 5 to 100 μm, and further preferably 10 to 60 μm.
As a method of forming the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition on the back surface of the surface base material, a method of applying the water-dispersed pressure-sensitive adhesive to the back surface of the base material sheet and drying it, Examples include a method in which the water-dispersed pressure-sensitive adhesive is applied to the release treatment surface, dried, and the formed pressure-sensitive adhesive layer is bonded to the back surface of the surface substrate.
Methods for applying the water-dispersed pressure-sensitive adhesive to the surface substrate or release sheet are conventionally known, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, and a curtain coating method. The method is mentioned.
The drying is usually preferably performed at 60 to 130 ° C, more preferably 80 to 120 ° C. The drying time is not particularly limited, but usually 10 seconds to 5 minutes is sufficient.
The release sheet is not particularly limited. Examples of the base material of the release sheet include paper, synthetic paper, and synthetic resin film. Examples of the paper include, for example, paper substrates such as high-quality paper, glassine paper, and coated paper, paper base materials such as laminated paper obtained by laminating a thermoplastic resin such as polyethylene and polypropylene to these paper base materials, and high-quality paper, Examples thereof include a paper base or the like that is subjected to a sealing treatment with glassine paper, coated paper, etc. with cellulose, starch, polyvinyl alcohol, acrylic-styrene resin, or the like. Examples of plastic synthetic resin films include films made of polyolefin resins such as polyethylene resins and polypropylene resins, films made of polyester resins such as polybutylene terephthalate resins and polyethylene terephthalate resins, and films obtained by subjecting these synthetic resin films to easy adhesion treatment. It is desirable that these are coated with a release agent.
Examples of the release agent include fluorine resins, silicone resins, and long-chain alkyl group-containing carbamates.
The pressure-sensitive adhesive sheet of the present invention is used as a pressure-sensitive adhesive sheet for sticking an adherend and is used by being attached to an adherend, and its use is not limited, but in particular, when the adherend is recycled and reused. It is preferable to use it by sticking to a kimono.
The pressure-sensitive adhesive sheet of the present invention can be suitably applied when the material of the surface base material of the pressure-sensitive adhesive sheet and the material constituting the adherend are the same.
Specific examples of the material constituting the adherend include an adherend composed of polystyrene resin, ABS resin, polycarbonate resin, or a mixture of two or more of the above resins.
The shape of the adherend is not particularly limited, and can be various shapes.

Next, the present invention will be described more specifically with reference to examples. In addition, this invention is not restrict | limited at all by these examples.
Example 1
(1) Preparation of water-dispersed pressure-sensitive adhesive composition In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, nitrogen inlet tube and dropping funnel, 100 parts by mass of 2-ethylhexyl acrylate, 0.2 parts by mass of acrylic acid, 0.4 parts by weight of methacrylic acid was charged, and 0.5 parts by weight of sodium polyoxyethylene alkyl ether sulfate (surfactant, trade name “Latemul E-118B”), polyoxyethylene alkyl allyl ether Ammonium sulfate (surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “AQUALON KH-05”) 0.1 part by mass, polyoxyethylene alkyl ether (surfactant, manufactured by Kao Corporation, trade name “Emulgen 103”) 1 0.0 part by mass, hydrogenated rosin ester-based tackifier (Rika Finetech, trade name “Rekatak F-105”) 2.0 Parts, 0.5 parts by mass of a terpene phenol tackifier (trade name “YS Polyester N-125” manufactured by Yasuhara Chemical Co., Ltd.) and 80 parts by mass of ion-exchanged water were added and stirred at room temperature. An emulsion of a mixture of saturated monomers was prepared in advance.
Separately, in a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen introduction tube and a dropping funnel, 28 parts by mass of ion-exchanged water is enclosed, and the temperature is raised to an internal temperature of 80 ° C. by filling nitrogen. While maintaining, 0.5 part by mass of a 10% by mass aqueous ammonium persulfate solution was added.
Next, the emulsion of the mixture of unsaturated monomers prepared in advance as described above was transferred to a dropping funnel and dropped over 4 hours. At the same time, 4 parts by mass of a 5% by mass ammonium persulfate aqueous solution was dropped, and emulsion polymerization was carried out at an internal temperature of 80 ° C.
After completion of dropping, the mixture was aged at 80 ° C. for 4 hours to obtain an acrylic copolymer emulsion. Then, after cooling to room temperature and neutralizing with ammonia water, water was added to obtain a water-dispersed pressure-sensitive adhesive composition having a solid content of 50% by mass and a pH of 8.0. The average particle diameter of the acrylic copolymer in the water-dispersed pressure-sensitive adhesive composition was 270 nm.
(2) Preparation of water-dispersed pressure-sensitive adhesive For 100 parts by mass of the water-dispersed pressure-sensitive adhesive composition obtained in (1) above, an emulsion-type rosin ester-based tackifier (trade name “Harrie, manufactured by Harima Chemical Co., Ltd.” Star SK-816 ") 3.0 parts by mass, emulsion type terpene phenol tackifier (Arakawa Chemical Industries, trade name" Tamanol E-100 ") 5.3 parts by mass, and polyoxyethylene alkyl as a plasticizer Amine (product name “Esomin C / 25” manufactured by Lion Akzo Co., Ltd.), R in formula (1) is an alkyl group having an average carbon number of 12 obtained from coconut oil, and x + y is 15. HLB value 15 .4) Add 0.6 parts by weight, and further add 3.0 parts by weight of a polyacrylic acid thickener (Rohm and Haas, trade name “Acrysol ASE-60”). 000mPa · s (BM type viscometer, 25 ° C., 60 rpm) to thicken the, to obtain an aqueous dispersion adhesive.
(3) Preparation of pressure-sensitive adhesive sheet To 100 parts by weight of the water-dispersed pressure-sensitive adhesive obtained in (2) above, 0.5 parts by weight of an epoxy-based crosslinking agent (trade name “Denacol EX-313” manufactured by Nagase ChemteX Corporation) The coating thickness after drying using a roll knife coater on the release-treated surface of a release sheet (made by Lintec Co., Ltd., glassine paper released by silicone resin, trade name “SP-8K Ao”) Was applied to a thickness of 20 μm and dried at 90 ° C. for 2 minutes to form an adhesive layer. After drying, the pressure-sensitive adhesive layer was bonded to a polystyrene resin film (manufactured by OG Co., Ltd., trade name “High Styrene PS65”, thickness 65 μm) and the pressure-sensitive adhesive layer on the release sheet, and the surface substrate was re-coated with the polystyrene resin film. A peelable adhesive sheet was prepared.
Similarly, as a surface base material, instead of polystyrene resin film, ABS resin film (manufactured by Shin-Etsu Polymer Co., Ltd., trade name “PSZ980”, thickness 80 μm), polycarbonate resin film (manufactured by Teijin Ltd., trade name “Pure Ace C-”) 110-100 ”, thickness 100 μm), a polycarbonate resin-ABS resin mixed film (Teijin Kasei's polycarbonate resin-ABS resin-based polymer alloy“ Multilon T2711 ”) using an inflation film forming machine at 240 ° C. 100 μm thick film obtained by extrusion while melting), a film made of a mixed resin of polycarbonate resin and polystyrene resin (polycarbonate resin (“NOVALEX 7027R” manufactured by Mitsubishi Engineering Plastics) and polystyrene resin “G690N” manufactured by Nippon Polystyrene Co., Ltd.) was mixed in equal amounts, and each film was obtained by extrusion molding while melting at 260 ° C. using an inflation film-forming machine. Removable adhesive sheet of ABS resin film, Removable adhesive sheet of polycarbonate resin film, Removable adhesive sheet of film made of polycarbonate resin-ABS resin mixed resin, Mixture of polycarbonate resin and polystyrene resin A re-peelable pressure-sensitive adhesive sheet made of a resin was prepared. Thus, five types of pressure-sensitive adhesive sheets having different surface base materials were prepared.
(Example 2)
In Example 1 (2), five different surface base materials were used in the same manner as in Example 1 except that the emulsion type rosin ester tackifier and the emulsion type terpene phenol tackifier were not added. An adhesive sheet was prepared.
(Example 3)
In (1) of Example 1, a hydrogenated rosin ester tackifier and a terpene phenol tackifier were not added. In (2) of Example 1, an emulsion-type hydrogenated rosin ester tackifier and emulsion Five types of pressure-sensitive adhesive sheets having different surface base materials were prepared in the same manner as in Example 1 except that the type terpene phenol-based tackifier was not added.
Example 4
In Example 1 (1), no terpene phenol tackifier was added, and in Example 1 (2), an emulsion rosin ester tackifier and an emulsion terpene phenol tackifier were not added. Except for the above, five types of pressure-sensitive adhesive sheets having different surface base materials were prepared in the same manner as in Example 1.
(Example 5)
In Example 1 (2), five types of pressure-sensitive adhesive sheets having different surface base materials were prepared in the same manner as in Example 1 except that the emulsion type terpene phenol-based tackifier was not added.
(Example 6)
In Example 1 (2), five types of pressure-sensitive adhesive sheets having different surface base materials were prepared in the same manner as in Example 1 except that the emulsion-type rosin ester-based tackifier was not added.
(Example 7)
Example 1 is the same as Example 1 except that the amount of polyoxyethylene alkylamine (product name “Esomine C / 25” manufactured by Lion Akzo Co., Ltd.) as a plasticizer is 0.4 parts by mass. Thus, five types of pressure-sensitive adhesive sheets having different surface base materials were prepared.
(Example 8)
Example 1 is the same as Example 1 except that the amount of polyoxyethylene alkylamine (product name “Esomine C / 25” manufactured by Lion Akzo Co., Ltd.) as a plasticizer is 0.2 parts by mass. Thus, five types of pressure-sensitive adhesive sheets having different surface base materials were prepared.
Example 9
In Example 1, as a plasticizer, polyoxyethylene alkylamine (manufactured by Lion Akzo Co., Ltd., trade name “Esomine O / 20”, R in Formula (1) is an oleyl group, and x + y is 10. HLB value 5 types of pressure-sensitive adhesive sheets having different surface base materials were prepared in the same manner as in Example 1 except that 0.6 part by mass of 12.5) was blended.
(Example 10)
In Example 1, polyoxyethylene alkylamine (manufactured by Lion Akzo Co., Ltd., trade name “Esomin C / 25”) as a plasticizer and polyoxyethylene alkylamine (manufactured by Lion Akzo Co., Ltd., trade name “Esomin O”) / 20 ") was prepared in the same manner as in Example 1 except that 0.3 parts by mass of each and 0.3 parts by mass in total were blended to prepare five types of pressure-sensitive adhesive sheets having different surface base materials.
(Comparative Example 1)
In Example 1 (1), 0.9 part by mass of sodium oxyethylene alkyl ether sulfate (surfactant, manufactured by Kao Corporation, trade name “Latemul E-118B”), polypropylene glycol cresol ether (surfactant, Japan) Emulsifier Co., Ltd., trade name “New Coal CF-6”) 0.5 part by mass, polyoxyethylene alkyl ether (surfactant, Kao Corporation, trade name “Emulgen 103”) 0.5 part by mass Then, the blending amount of the hydrogenated rosin tackifier was 2.5 parts by mass, and no terpene phenol tackifier was added. In Example 1 (2), polyoxyethylene alkylamine was used as a plasticizer. Without blending, 2.0 parts by mass of diglycerin (manufactured by Tokyo Chemical Industry Co., Ltd., trade name “diglycerol”) and triethanolamine (Nippon Catalyst) Ltd.)) Ltd.) except that the 2.5 parts by mass is in the same manner as in Example 1. In the same manner as in Example 1, surface substrate creates the five different adhesive sheet.
Tables 1 and 2 show the composition of the water-dispersed pressure-sensitive adhesive used in the pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets of Examples and Comparative Examples, and the results of the peel test of the pressure-sensitive adhesive sheet. In Tables 1 and 2, the unit of the numerical value indicating the blending amount of the blending component of the water-dispersed adhesive is part by mass.
The peel test of the pressure-sensitive adhesive sheet was performed and evaluated by the following method.
(1) Peel test As an adherend, a polystyrene resin film (manufactured by OG Co., Ltd., trade name “High Styrene PS65”, thickness 65 μm), an ABS resin film (manufactured by Shin-Etsu Polymer Co., Ltd., trade name “PSZ980”, thickness 80 μm), Polycarbonate resin film (manufactured by Teijin Ltd., trade name “Pure Ace C-110-100”, thickness 100 μm), polycarbonate resin-ABS resin mixed resin (PC-ABS resin) (polycarbonate resin produced by Teijin Chemicals Ltd.) ABS resin-based polymer alloy “Multilon T2711” is extruded at 100 ° C. while being melted at 240 ° C. using an inflation film forming machine, and a polycarbonate resin-polystyrene resin mixed resin (PC-PS). Resin film (polycarbonate) To resin (“Novalex 7027R” manufactured by Mitsubishi Engineering Plastics) and polystyrene resin (“G690N” manufactured by Nippon Polystyrene Co., Ltd.) are mixed in equal amounts and melted at 260 ° C. using an inflation film forming machine. Five types of films having a thickness of 100 μm obtained by extrusion molding were prepared. This film was fixed to a plate to form an adherend.
The adhesive sheet of the surface base material of the adhesive sheet and the adhesive sheet and the adherend in which the resin constituting the adherend is the same are bonded together at room temperature, and then 7 days in an environment of 60 ° C. and 95% RH. It was left to stand and then returned to room temperature, and the pressure-sensitive adhesive sheet was peeled off from the adherend at room temperature. Whether or not there was any adhesive residue on the surface of the adherend from which the pressure-sensitive adhesive sheet was peeled was visually observed and evaluated according to the following criteria.
A: No adhesive residue on the surface of the adherend.
X: There was adhesive residue on the surface of the adherend.

The pressure-sensitive adhesive sheet of the present invention can be affixed to various adherends such as home appliances and resin casings of electronic devices.

Claims

A pressure-sensitive adhesive sheet comprising a surface base material and a pressure-sensitive adhesive layer provided on the back surface of the surface base material, wherein the pressure-sensitive adhesive layer is obtained by emulsion polymerization of 2-ethylhexyl acrylate and ethylenically unsaturated carboxylic acid It is formed by applying a water-dispersed pressure-sensitive adhesive prepared by adding an amino group-containing nonionic surfactant as a plasticizer to a water-dispersed pressure-sensitive adhesive composition containing an acrylic copolymer. A featured adhesive sheet.
The pressure-sensitive adhesive sheet according to claim 1, wherein the surface base material is composed of the same material as that of the adherend to which the pressure-sensitive adhesive sheet is attached.
The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the surface substrate is composed of a polystyrene resin, an acrylonitrile-butadiene-styrene copolymer resin, a polycarbonate resin, or a mixture of two or more of the resins.
The acrylic copolymer is an acrylic copolymer obtained by emulsion polymerization of 2-ethylhexyl acrylate, an ethylenically unsaturated carboxylic acid, and other unsaturated monomers copolymerizable if necessary. Item 4. The pressure-sensitive adhesive sheet according to any one of Items 1 to 3.