KR101522231B1 - Adhesive sheet for metal surface bonding - Google Patents

Abstract

A pressure-sensitive adhesive sheet laminated on a metal surface, wherein the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer comprising an acrylic pressure-sensitive adhesive using a (meth) acrylic acid ester copolymer, Wherein the content of the alkyl ester monomer (A) is 50 mass% or more and the content of the alkyl (meth) acrylate (B) having an alkyl group having 1 to 4 carbon atoms is 5 to 45 mass% The content of the carboxyl group-containing monomer in the monomer component constituting the acrylic adhesive sheet is 1% by mass or less, it is possible to reduce the white turbidity and corrosion of the metal under high temperature and high humidity conditions.

Description

ADHESIVE SHEET FOR METAL SURFACE BONDING [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pressure-sensitive adhesive sheet to be attached to a metal surface.

Recently, touch sensors are beginning to be mounted on electronic devices. A touch sensor for electronic equipment is mainly equipped with a resistive touch panel which is detected by the pressure at the time of input and a capacitive touch panel which detects an input position by static electricity from the human body at the time of input. Due to the multifunctionality of the method, the electrostatic capacity method has become mainstream. A transparent metal film having a conductive layer provided on a transparent film base material or glass is used for the touch panel. In a capacitive touch panel, the metal layer surface of the transparent metal film is fixed so as to be in contact with the surface of the pressure sensitive adhesive layer of the double-sided pressure sensitive adhesive sheet.

The metal layer of the transparent metal film is formed by depositing a metal having high transparency and conductivity, such as indium tin oxide, for example. When the double-sided pressure-sensitive adhesive sheet is laminated so that the pressure-sensitive adhesive layer is in contact with the metal layer surface of the metal film, The oxidation reaction of the metal occurs, and the conductive function is deteriorated. For this reason, the double-sided pressure-sensitive adhesive sheet for metal side attachment has been required to have high metal corrosion resistance.

As the double-sided pressure-sensitive adhesive sheet having metal corrosion-preventive properties, a double-sided pressure-sensitive adhesive sheet containing no acid component (see, for example, Patent Documents 1 to 3) has been proposed since the acid component contained in the pressure- have. The double-sided pressure-sensitive adhesive sheet has metal corrosion-preventive properties by a pressure-sensitive adhesive layer which does not contain an acid component which causes corrosion of the metal. However, the pressure-sensitive adhesive sheet containing no acid component has a problem that the hydrophilic property of the pressure-sensitive adhesive layer is lowered and the pressure-sensitive adhesive layer becomes turbid under high temperature and high humidity.

Japanese Patent Application Laid-Open No. 2010-215794 Japanese Patent Application Laid-Open No. 2009-79203 Japanese Patent Application Laid-Open No. 2010-215923

A problem to be solved by the present invention is to provide a pressure-sensitive adhesive sheet which does not corrode a metal surface even when it is directly adhered to a metal surface, and in which visibility is not lowered due to opacity under a high temperature environment.

In the present invention, a (meth) acrylic acid ester copolymer obtained by copolymerizing a specific amount of a (meth) acrylic acid alkyl ester monomer and a (meth) acrylic acid alkyl ester monomer having an alkyl group of 1 to 4 carbon atoms in a pressure- A pressure-sensitive adhesive sheet which does not cause turbidity and corrosion of metal under high-temperature and high-humidity conditions is realized.

That is, the present invention provides a pressure sensitive adhesive sheet laminated on a metal surface, wherein the pressure sensitive adhesive sheet has a pressure sensitive adhesive layer comprising an acrylic pressure sensitive adhesive using a (meth) acrylic acid ester copolymer, wherein the (meth) (Meth) acrylic acid alkyl ester (A) having an alkyl group of 1 to 4 carbon atoms and an alkyl (meth) acrylate ester (B) having an alkyl group of 1 to 4 carbon atoms as a monomer component and the (meth) acrylic acid ester copolymer (Meth) acrylic acid alkyl ester (B) having an alkyl group of 1 to 4 carbon atoms in an amount of 5 to 45% by mass, the content of the (meth) acrylic acid alkoxyalkyl ester monomer (A) It is desirable to provide a pressure sensitive adhesive sheet for metal side patches wherein the content of the carboxyl group-containing monomer in the monomer component constituting the acrylic ester copolymer is 1% by mass or less .

The pressure-sensitive adhesive sheet for a metal side adhesive patch of the present invention is a pressure-sensitive adhesive sheet for a metal side adhesive patch which comprises (meth) acrylic acid ester copolymer (meth) The content of the carboxyl group-containing monomer is small, the hydrophilic property of the pressure-sensitive adhesive layer is high and the pressure-sensitive adhesive layer is not cloudy under high temperature and high humidity conditions, and corrosion of the metal can be further prevented.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a configuration example of an image display apparatus to which a pressure sensitive adhesive sheet for a metal side patch according to the present invention is applied. Fig.
2 is a schematic view showing a configuration example of an image display apparatus to which a pressure sensitive adhesive sheet for a metal side patch according to the present invention is applied.
3 is a schematic view showing a configuration example of an image display apparatus to which a pressure sensitive adhesive sheet for a metal side patch according to the present invention is applied.

The pressure sensitive adhesive sheet for a metal side adhesive patch of the present invention is a pressure sensitive adhesive sheet laminated to a metal surface, wherein the pressure sensitive adhesive layer of the pressure sensitive adhesive sheet comprises a (meth) acrylic acid alkoxyalkylester monomer (A) and an alkyl group having 1 to 4 carbon atoms (Meth) acrylic acid alkyl ester monomer (B) as a main monomer, wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer composed of a (meth) acrylic acid alkyl ester monomer Wherein the content of the (A) is 50% by mass or more, the content of the (meth) acrylic acid alkyl ester monomer (B) having an alkyl group of 1 to 4 carbon atoms is 5 to 45% by mass and the content of the monomer containing a carboxyl group is 1% Is an adhesive sheet.

[(Meth) acrylic acid ester copolymer]

Specific examples of the (meth) acrylic acid alkoxyalkyl ester monomer (A) constituting the (meth) acrylic acid ester copolymer of the present invention include 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, Glycol, 3-methoxypropyl acrylate, 3-ethoxypropyl acrylate, 4-methoxybutyl acrylate, and 4-ethoxybutyl acrylate. Among them, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate are particularly preferable. By using the monomer, a cohesive force necessary for fixing the metal film to the pressure-sensitive adhesive layer can be imparted.

In the present specification, acrylic acid and methacrylic acid are collectively referred to as (meth) acrylic acid, and their derivatives are represented in the same manner.

The content of the (meth) acrylic acid alkoxyalkyl ester monomer (A) relative to 100 mass% of the total monomer component constituting the (meth) acrylic acid ester copolymer is preferably 50 to 90 mass%, more preferably 60 to 90 mass% By mass, more preferably from 70 to 90% by mass, and particularly preferably from 75 to 85% by mass. By setting the content of the (meth) acrylic acid alkoxyalkyl ester monomer (A) within the range, the hydrophilic property of the pressure-sensitive adhesive layer is enhanced, and it is not cloudy under high temperature and high humidity.

Examples of the (meth) acrylic acid alkyl ester monomer (B) having an alkyl group of 1 to 4 carbon atoms constituting the (meth) acrylic acid ester copolymer of the present invention include a (meth) acrylic acid ester monomer other than the (meth) acrylic acid alkoxyalkyl ester monomer (A) Specific examples of the alkyl acrylate monomer include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, t-butyl acrylate, methyl methacrylate, Propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, and t-butyl methacrylate.

Among them, n-butyl acrylate is particularly preferable. By using n-butyl acrylate, it is possible to achieve both high adhesion to the metal surface and anti-whitening resistance under high temperature and high humidity conditions.

The content of the (meth) acrylic acid ester monomer (B) having 1 to 4 carbon atoms relative to 100 mass% of the total monomer component constituting the (meth) acrylic acid ester copolymer is preferably 5 to 45 mass%, more preferably 5 to 35 mass% , More preferably from 5 to 25 mass%, and particularly preferably from 10 to 25 mass%. By setting the content of the (meth) acrylic acid ester monomer (B) within the range, it is possible to achieve both the high adhesion to the metal surface and the whitening resistance under high temperature and high humidity conditions.

Examples of the carboxyl group-containing monomer constituting the (meth) acrylic acid ester copolymer of the present invention include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, acrylic acid dimer, ethylene oxide modified succinic acid acrylate, have. Of these, acrylic acid is preferred because of its high versatility.

The amount of the carboxyl group-containing monomer to be used is 1% by mass or less, more preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and particularly preferably substantially no content of the monomer component constituting the acrylic copolymer. By setting the content of the carboxyl group-containing monomer within the range, corrosion of the metal can be prevented.

It is also preferable to use a vinyl monomer having a functional group which reacts with the crosslinking agent to increase the cohesive force of the pressure-sensitive adhesive layer by carrying out a crosslinking reaction favorably with the crosslinking agent. Examples of the vinyl monomer having a functional group that reacts with the crosslinking agent include, but are not particularly limited to, hydroxyl group-containing vinyl monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and 4-hydroxybutyl acrylate.

The amount of the vinyl monomer having a functional group is preferably 0.1% by mass to 10% by mass, particularly preferably 0.5% by mass to 5% by mass, in the monomer component constituting the acrylic copolymer.

The weight average molecular weight Mw of the (meth) acrylic acid ester copolymer is preferably from 300,000 to 1.6 million, more preferably from 400,000 to 1,300, and still more preferably from 500,000 to 1,000,000. When the weight average molecular weight Mw of the (meth) acrylic acid ester copolymer is within the above range, adhesiveness to the metal surface and conformability to the unevenness of the metal or the display panel adhered thereto can be given preferentially.

The molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of the (meth) acrylic acid ester copolymer is preferably 10 to 50, more preferably 10 to 30, and further preferably 10 to 20. If the molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of the (meth) acrylic acid ester copolymer is within this range, it is possible to impart followability to the unevenness of the metal to be pasted or the display panel, And it is also possible to suppress peeling on the metal surface.

In the present invention, the weight average molecular weight Mw of the carboxyl group-containing (meth) acrylic acid ester copolymer (A) can be measured by a gel permeation chromatograph (GPC). More specifically, it can be determined by measuring the GPC measurement conditions under the following GPC conditions, using a polystyrene conversion value using "SC8020" manufactured by TOSOH CORPORATION as a GPC measurement device.

(Measurement conditions of GPC)

Sample concentration: 0.5% by mass (tetrahydrofuran solution)

Sample injection volume: 100 μL

Eluent: tetrahydrofuran (THF)

Flow rate: 1.0 mL / min

· Column temperature (measuring temperature): 40 ° C

Column: "TSKgel GMHHR-H" manufactured by Tosoh Corporation

· Detector: Differential refraction

The polymerization method of the (meth) acrylic acid ester copolymer to be used in the present invention is not particularly limited, and various known polymerization methods can be appropriately used, and a thermal polymerization method such as a solution polymerization method, an emulsion polymerization method, , A polymerization method in which an active energy ray such as light or radiation is irradiated, or the like can be adopted. From the viewpoints of workability and quality stability, the solution polymerization method can be preferably employed, and any one of a batch injection system in which all the monomer components are supplied to the reaction vessel at one time, a dropping system in which continuous or divided supply is possible, and the like.

As the solvent used in the solution polymerization, various organic solvents used for solution polymerization can be used, and among them, non-toluene organic solvents are preferably used. Preferred examples of the organic solvent include ethyl acetate, hexane, cyclohexane, methylcyclohexane, isopropyl alcohol and the like. Examples of the organic solvent that can be preferably used include 1-butanol, sec-butanol, tert-butanol, tert-butyl methyl ether, methyl ethyl ketone, acetylacetone and 1,2-dichloroethane.

[Pressure sensitive adhesive composition]

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for a metal side patch of the present invention is a pressure-sensitive adhesive composition containing the above-mentioned (meth) acrylic acid ester copolymer, wherein the composition has, as components other than the copolymer, It is preferable to contain a crosslinking agent.

Examples of the crosslinking agent to be used include an isocyanate crosslinking agent, an epoxy crosslinking agent, a chelating crosslinking agent, an azirine crosslinking agent and a polyfunctional acrylate-based crosslinking agent. Among them, isocyanate-based crosslinking agents excellent in reactivity with components of the (meth) acrylic copolymer are preferable.

The blending amount of the crosslinking agent to be added to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is preferably 0.05 to 2 parts by mass, more preferably 0.07 to 1.5 parts by mass, further preferably 0.1 to 1 part by mass. By setting the content of the cross-linking agent within the range, it is easy to adjust the gel fraction of the pressure-sensitive adhesive layer to a favorable range.

The pressure-sensitive adhesive composition of the present invention is preferably a pressure-sensitive adhesive composition in which the (meth) acrylic acid ester copolymer and the crosslinking agent are dissolved or dispersed in a solvent. As the solvent, a solvent such as a solvent used in the solution polymerization can be preferably used have.

The pressure-sensitive adhesive composition of the present invention may contain other general additives such as an ultraviolet absorber, a light stabilizer, an anti-aging agent, a peeling agent, a tackifier, a plasticizer, a softener, a filler, ), A surfactant, and the like may be contained.

[Adhesive sheet for metal side patch]

The pressure-sensitive adhesive sheet for a metal surface patch according to the present invention has a pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive composition as a pressure-sensitive adhesive layer, thereby suppressing the opacity of the pressure-sensitive adhesive layer under high temperature and high humidity conditions and corrosion of the metal.

The pressure sensitive adhesive sheet for metal side patch according to the present invention may have a film base material, or may be a pressure sensitive adhesive sheet having no film base material and composed of only a pressure sensitive adhesive layer. Further, the pressure-sensitive adhesive layer may be a single layer or a plurality of layers may be laminated. Depending on the intended use, a single-sided adhesive sheet or a double-sided adhesive sheet may be used.

The pressure sensitive adhesive sheet of the present invention can be fixed between parts, for example, by fixing a surface protection panel on the surface of an image display device and a member having a metal surface such as ITO film or glass, Sensitive adhesive sheet, it is preferable to use a double-sided pressure-sensitive adhesive sheet in the form of a pressure-sensitive adhesive sheet having no substrate and having only a pressure-sensitive adhesive layer . The double-sided pressure-sensitive adhesive sheet of this type is particularly favorable in the case of a member having a surface relief shape such as a surface protection panel in which one member has a printing step. In addition, when the surface protective panel and the ITO glass are used as a pressure-sensitive adhesive sheet for preventing scattering of the ITO-treated panel or the spliced panel when the surface of the surface protective panel is broken, The form of the sheet can be preferably used. In particular, the form of the single-sided pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is provided on one side of the film substrate provided with the hard coating layer on one side can be preferably used.

When the pressure sensitive adhesive sheet for a metal side patch of the present invention has a film base, a transparent film base can be used as the base. Examples of the transparent substrate include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, diacetylcellulose film, triacetylcellulose film, acetylcellulose butyrate film, polyvinyl chloride Film, a polyvinylidene chloride film, a polyvinyl alcohol film, an ethylene-vinyl acetate copolymer film, a polystyrene film, a polycarbonate film, a polymethylpentene film, a polysulfone film, a polyetheretherketone film, A mid-film, a polyimide film, a fluororesin film, a nylon film, and an acrylic resin film. Among them, polyethylene terephthalate excellent in transparency and smoothness is preferable.

For the purpose of improving the adhesion with the pressure-sensitive adhesive layer, the film base used in the pressure-sensitive adhesive sheet for metal side patch of the present invention may be subjected to a surface unevenness treatment such as a sand blasting method or a solvent treatment method, a corona discharge treatment, Surface treatment such as surface oxidation treatment such as treatment, hot air treatment, ozone / ultraviolet ray irradiation treatment and the like can be performed.

It is also preferable that the film substrate of the pressure sensitive adhesive sheet for metal side patches of the present invention is a hard coating film having at least a hard coating layer on one side thereof in order to prevent appearance defects such as scars and scratches mixed in the production process. Among them, a hard coat layer containing an acrylic resin is preferable. By containing an acrylic resin, adhesiveness to the hard coated surface can be ensured. In addition, the adhesive sheet for metal side adhesive patches provided with the adhesive layer on one side of the hard coat film can be suitably used as the adhesive sheet for scattering prevention.

When the pressure sensitive adhesive sheet for metal side patches of the present invention is a pressure sensitive adhesive sheet for a metal side patch with a pressure sensitive adhesive layer provided on one side of a hard coating film and the pressure sensitive adhesive sheet is used as a pressure sensitive adhesive sheet for scattering prevention, It is preferable that the surface pencil hardness is B or more, preferably F or more. The thickness of the hard coat layer is preferably 1 to 5 mu m.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for a metal side patch of the present invention preferably has a gel fraction represented by the following formula when immersed in toluene for 24 hours in an amount of 30 to 80 mass%, more preferably 30 to 70 mass% By mass, and most preferably from 35 to 55% by mass. When the gel fraction of the pressure-sensitive adhesive layer is within the above-mentioned range, it is easy to suppress the peeling at the time of fixation in fixing of the metal surface, and it is possible to impart followability to the metal or the unevenness of the display panel, It is difficult to leave bubbles.

Gel fraction (mass%) = [(mass after immersion of toluene in the pressure-sensitive adhesive layer) / (mass before immersion in toluene in pressure-sensitive adhesive layer)] × 100

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for a metal side patch of the present invention preferably has a storage elastic modulus at 70 캜 in a dynamic viscoelastic spectrum measured at a frequency of 1 Hz in a range of 4.0 x 10 ^{4 to} 9.0 x 10 ^{5 and, 4.0 × 10 4 ~8.0 × 10} 4 is more ^{preferable, 4.0 × 10 4 ~7.0 × 10} 4 is most preferred. By including the storage elastic modulus in this range, both the fluidity following the step portion and the suppression of peeling due to warping can be achieved.

The dynamic viscoelasticity of the pressure-sensitive adhesive layer in the present invention was measured by viscoelasticity test using a viscoelasticity tester (product name: Ares 2 KSTD, manufactured by Leo Matrix Co., Ltd.) (G ') and the loss elastic modulus (G' '). The test piece may be sandwiched between the parallel discs with a thickness of 0.5 to 2.5 mm, but it is preferable that the laminate of the substrate and the pressure- In the latter case, the thickness of only the adhesive is adjusted to be within the above range.

The transparency of the adhesive sheet for metal side patches of the present invention preferably has a total light transmittance of 80% or more and a haze of 1.0% or less, more preferably 90% or more of total light transmittance and 0.5% or less of haze. When the transparency of the transparent conductive film is within the above range, the transparency of the display mounted with the touch panel device in which the adhesive film is used tends to be maintained.

The metal onto which the pressure sensitive adhesive sheet for a metal side patch of the present invention is applied is not particularly limited, and specific examples thereof include indium tin oxide, indium oxide, tin oxide, zinc oxide, cadmium oxide, gallium oxide and titanium oxide .

The pressure sensitive adhesive sheet for metal side patches of the present invention was pressed against a metal at a temperature of 23 캜 and a relative humidity of 50% RH by using a 2 kg roller at a reciprocating number of times of one reciprocation, and the pressure was 300 mm / min It is preferable that the 180 deg. Peel adhesion force is 5 to 20 N / 25 mm for metal. Within the above range, peeling at the end face in the fixing of the transparent conductive film is easily suppressed, and the peeling of the adhesive sheet in the defective compound in the manufacturing process becomes possible.

The thickness of the pressure sensitive adhesive sheet for metal side patches of the present invention may be appropriately selected depending on the intended use, but is preferably 5 to 500 占 퐉. Among them, in the case of adhering to a smooth surface, it is easy to make the touch panel device thin by adjusting the thickness to 10 to 250 mu m. Further, in the case of attaching to a surface having steps or irregularities, the thickness of the pressure-sensitive adhesive layer is preferably 20 占 퐉 or more, and particularly preferably 25 to 150 占 퐉.

The pressure sensitive adhesive sheet for metal surface patch of the present invention can be produced by a commonly used method. For example, it can be produced by forming a pressure-sensitive adhesive layer on a film base material or a release sheet. Specifically, the composition of the pressure-sensitive adhesive is applied directly onto the base film and dried, cured or polymerized, or once coated on a release sheet, dried or cured and polymerized to form a pressure-sensitive adhesive layer, Or a method of bonding to a pressure-sensitive adhesive layer or a substrate film thus produced.

[Usage]

The pressure-sensitive adhesive sheet for a metal surface patch of the present invention has a good whitening resistance without corroding a metal surface, and therefore can be applied to ITO glass or ITO film provided with glass indium tin oxide (ITO) on the surface of glass or film, Can be suitably used when fixing a member having a metal surface such as a metal wiring film provided with wiring of silver or copper. In particular, it can be used to fix a member having a metal surface that requires high transparency and is required to have stable conductivity. In addition, the pressure sensitive adhesive sheet for metal side patch according to the present invention can achieve favorable step contactability, so that the fixing member can be suitably applied to a member having a surface relief shape, for example, a member provided with a printing step.

As a customary example of applying the pressure sensitive adhesive sheet for a metal side patch of the present invention, for example, there is known a pressure sensitive adhesive sheet for use in a touch sensor used in an electronic device image display unit, which is required to have high transparency and stable conductivity, The film and the surface protection panel can be fixed, or the ITO can be used to fix the polyethylene terephthalate films deposited on one surface. As a specific example of the image display apparatus having such a configuration, a configuration as shown in Fig. 1 can be preferably exemplified. The application example shown in Fig. 1 is an example of a surface protection panel 2 having a printing step 3 and an ITO film 4 having an ITO surface 4b on a transparent resin film 4a, The adhesive sheet of the present invention is used for fixing by the adhesive sheet for metal side patches 1 of the present invention, and the adhesive sheet of the present invention can be used suitably for such applications. An image display module 6 such as an LCD module is housed in the housing 5. The transparent resin film 4a side of the housing and the ITO film 4 'is bonded to an adhesive member 7 such as an adhesive tape or an adhesive tape, And the surface of the ITO film 4 'of the ITO film 4' and the surface of the transparent resin film 4a of the ITO film 4 are fixed to each other by a substrate- And can be suitably used for a purpose of being fixed by the sheet 1 '.

In addition, it can be suitably used as a pressure-sensitive adhesive film for the purpose of fixing a glass and a surface protective panel deposited on one surface with acid-graded indium tin in a touch sensor used in an electronic device image display unit or preventing scattering during glass breakage. As a specific example of the image display apparatus having such a configuration, the configurations shown in Figs. 2 and 3 can be preferably exemplified. The application example in Fig. 2 is an example in which the ITO surface 14 of the surface protection panel 12 having the ITO surface 14 whose one surface is treated with ITO and the printing step 13 is provided on the surface thereof, Of the present invention is an example of applying the adhesive sheet 11 for a metal surface patch of the present invention having the adhesive layer 15 on one side of the hard coating film 16 as the adhesive sheet for anti- In this configuration, the hard coating film 16 of the adhesive sheet 11 for metal side patches and the housing 17 having the image display module 18 such as an LCD module are fixed by the adhesive member 19 . The application example shown in Fig. 3 includes a surface protection panel 22 having a printing step 23 and an ITO glass 24 having ITO surfaces 24b and 24c on the transparent glass 24a, -Less of the present invention with the adhesive sheet 21 for a metal side patch of the present invention, and the adhesive sheet of the present invention can be suitably applied as in the case of Fig. The adhesive sheet 21 'for a metal surface patch of the present invention having the adhesive layer 26 on one surface of the hard coating film 25 may be applied as the adhesive sheet for scattering the ITO glass 24. 2, a housing 27 having a hard coating film 25 of an adhesive sheet 21 'for a metal face patch and an image display module 28 such as an LCD module is attached to an adhesive member 29 ).

[Example]

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples.

≪ Acrylic copolymer (1) >

Preparation of acrylic copolymer To a reaction vessel equipped with a stirrer, a cold current cooler, a thermometer, a dropping funnel and a nitrogen gas inlet, 75 mass% of 2-methoxyethyl acrylate, 24 mass% of n-butyl acrylate, 1 mass of acrylic acid hydroxyethyl And 0.2 part of 2,2'-azobisisobutylnitrile as a polymerization initiator were dissolved in 100 parts by mass of ethyl acetate, and after nitrogen replacement, the mixture was polymerized at 80 ° C for 8 hours to obtain an acrylic ester copolymer (1) having a weight average molecular weight of 700,000 .

≪ Acrylic copolymer (2) >

Acrylic acid ester copolymer (2) having a weight average molecular weight of 700,000 was obtained in the same manner as in the acrylic ester copolymer (1) except that the acrylic acid ester copolymer (1) was changed to 85% by mass of 2-methoxyethyl acrylate and 14% by mass of n-butyl acrylate.

≪ Acrylic copolymer (3) >

Preparation of acrylic copolymer A reaction vessel equipped with a stirrer, a current-flow cooler, a thermometer, a dropping funnel and a nitrogen gas inlet was charged with 70 mass% of 2-methoxyethyl acrylate, 29 mass% of 2-ethylhexyl acrylate, 1 mass of acrylic acid hydroxyethyl And 0.2 part of 2,2'-azobisisobutylnitrile as a polymerization initiator were dissolved in 100 parts by mass of ethyl acetate, and after nitrogen replacement, the mixture was polymerized at 80 DEG C for 8 hours to obtain an acrylic ester copolymer (3) having a weight average molecular weight of 1,000,000 .

≪ Acrylic copolymer (4) >

Acrylic acid ester copolymer (4) having a weight average molecular weight of 1,000,000 was obtained in the same manner as in the acrylic acid ester copolymer (1) except that 50 mass% of 2-methoxyethyl acrylate and 49 mass% of n-butyl acrylate were used.

≪ Acrylic copolymer (5) >

Preparation of acrylic copolymer 80 parts by mass of n-butyl acrylate, 19 parts by mass of methyl methacrylate and 1 part by mass of hydroxyethyl acrylate were added to a reaction vessel equipped with a stirrer, a cold current cooler, a thermometer, a dropping funnel and a nitrogen gas inlet, 0.2 part of 2,2'-azobisisobutylnitrile as an initiator was dissolved in 100 parts by mass of ethyl acetate, and after nitrogen substitution, the mixture was polymerized at 80 DEG C for 8 hours to obtain an acrylic ester copolymer (5) having a weight average molecular weight of 800,000.

≪ Acrylic copolymer (6) >

Preparation of acrylic copolymer 80 parts by mass of n-butyl acrylate, 19 parts by mass of acrylic acid, 1 part by mass of hydroxyethyl acrylate and 2 parts by mass of a polymerization initiator were added to a reaction vessel equipped with a stirrer, a cold current cooler, a thermometer, a dropping funnel and a nitrogen gas inlet. Azobisisobutylnitrile were dissolved in 100 parts by mass of ethyl acetate, and the mixture was subjected to polymerization at 80 deg. C for 8 hours after replacing nitrogen to obtain an acrylic ester copolymer (6) having a weight average molecular weight of 700,000.

≪ Acrylic copolymer (7) >

Preparation of acrylic copolymer To a reaction vessel equipped with a stirrer, a cold current cooler, a thermometer, a dropping funnel and a nitrogen gas inlet, 75 mass% of 2-methoxyethyl acrylate, 16 mass% of n-butyl acrylate, 8 mass of methyl methacrylate %, 1% by mass of hydroxyethyl acrylate and 0.2% of 2,2'-azobisisobutylnitrile as a polymerization initiator were dissolved in 100% by mass of ethyl acetate, and after nitrogen substitution, the mixture was polymerized at 80 ° C for 8 hours to obtain a Acrylic acid ester copolymer (7).

≪ Acrylic copolymer (8) >

Preparation of acrylic copolymer To a reaction vessel equipped with a stirrer, a current-flow cooler, a thermometer, a dropping funnel and a nitrogen gas inlet, 75 mass% of 2-methoxyethyl acrylate, 24 mass of n-butyl acrylate, And 8 parts of 2,2'-azobisisobutylnitrile as a polymerization initiator were dissolved in 100 parts by mass of ethyl acetate, and after nitrogen replacement, the mixture was polymerized at 80 DEG C for 8 hours to obtain an acrylic ester copolymer (8) having a weight- .

≪ Acrylic copolymer (9) >

An acrylic ester copolymer (9) having a weight average molecular weight of 700,000 was obtained in the same manner as the acrylic ester copolymer (1) except that the content of n-butyl acrylate was changed to 22 mass% and hydroxyethyl acrylate was changed to 3 mass%.

≪ Acrylic copolymer (10) >

Preparation of acrylic copolymer To a reaction vessel equipped with a stirrer, a cold current cooler, a thermometer, a dropping funnel and a nitrogen gas inlet were added 40 mass% of 2-methoxyethyl acrylate, 24 mass% of n-butyl acrylate, 35 mass of 2 ethylhexyl acrylate %, 1% by mass of hydroxyethyl acrylate and 0.2% of 2,2'-azobisisobutylnitrile as a polymerization initiator were dissolved in 100% by mass of ethyl acetate, and after nitrogen substitution, the mixture was polymerized at 80 ° C for 8 hours to obtain a Acrylic acid ester copolymer (10).

≪ Acrylic copolymer (11) >

Preparation of acrylic copolymer To a reaction vessel equipped with a stirrer, a cold current cooler, a thermometer, a dropping funnel and a nitrogen gas inlet were added 70 mass% of 2-methoxyethyl acrylate, 24 mass% of n-butyl acrylate, 1 mass of acrylic acid hydroxyethyl % Of acrylic acid, 5 parts by mass of acrylic acid and 0.2 parts of 2,2'-azobisisobutylnitrile as a polymerization initiator were dissolved in 100 parts by mass of ethyl acetate, and the mixture was polymerized at 80 deg. C for 8 hours after replacing nitrogen, (11) was obtained.

≪ Pressure-sensitive adhesive composition (a) >

The acrylic acid ester copolymer (1) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive composition (a) having a resin solid content of 30 mass%.

≪ Pressure-sensitive adhesive composition (b) >

The acrylic acid ester copolymer (2) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive composition (b) having a resin solid content of 30 mass%.

≪ Pressure-sensitive adhesive composition (c) >

The acrylic acid ester copolymer (3) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive composition (c) having a resin solid content of 30 mass%.

≪ Pressure-sensitive adhesive composition (d) >

The acrylic acid ester copolymer (4) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive composition (d) having a resin solid content of 30 mass%.

≪ Pressure-sensitive adhesive composition (e) >

The acrylic acid ester copolymer (5) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive composition (e) having a resin solid content of 30 mass%.

≪ Pressure-sensitive adhesive composition (f)

The acrylic acid ester copolymer (6) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive composition (f) having a resin solid content of 30 mass%.

≪ Pressure sensitive adhesive composition (g) >

The acrylic acid ester copolymer (7) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive composition (g) having a resin solid content of 30 mass%.

≪ Pressure sensitive adhesive composition (h) >

The acrylic acid ester copolymer (8) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive composition (h) having a resin solid content of 30 mass%.

≪ Pressure-sensitive adhesive composition (i) >

The acrylic acid ester copolymer (9) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive composition (i) having a resin solid content of 30 mass%.

≪ Pressure-sensitive adhesive composition (j) >

The acrylic acid ester copolymer (10) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive composition (j) having a resin solid content of 30 mass%.

≪ Pressure-sensitive adhesive composition (k) >

The acrylic acid ester copolymer (11) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive composition (k) having a resin solid content of 30 mass%.

(Example 1)

To 100 parts by mass of the pressure-sensitive adhesive composition (a), 0.1 part by mass of an isocyanate crosslinking agent (Coronate HX, solid content 75%, manufactured by Nippon Polyurethane Co., Ltd.) was added and stirred for 15 minutes. Thereafter, (Hereinafter referred to as "# 75 release film ") having a thickness of 50 mu m after drying, and dried at 75 DEG C for 5 minutes. The obtained pressure-sensitive adhesive sheet and a polyester film (hereinafter referred to as # 38 release film) having a thickness of 38 탆 and one side of which was treated with a silicone compound were bonded. Thereafter, it was aged at 23 캜 for 7 days to obtain a substrate-less pressure-sensitive adhesive sheet having a thickness of 50 탆 and a gel fraction of 50%.

(Example 2)

A pressure-sensitive adhesive sheet having a gel fraction of 40% was obtained in the same manner as in Example 1 except that the isocyanate crosslinking agent was changed to 0.08 parts by mass.

(Example 3)

A pressure-sensitive adhesive sheet having a gel fraction of 50% was obtained in the same manner as in Example 1 except that 100 parts by mass of the pressure-sensitive adhesive composition (a) was changed to 100 parts by mass of the pressure-sensitive adhesive composition (b).

(Example 4)

A pressure-sensitive adhesive sheet having a gel fraction of 40% was obtained in the same manner as in Example 1 except that 100 parts by mass of the pressure-sensitive adhesive composition (a) was replaced with 100 parts by mass of the pressure-sensitive adhesive composition (b) and 0.08 parts by mass of the isocyanate-based crosslinking agent.

(Example 5)

A pressure-sensitive adhesive sheet having a gel fraction of 50% was obtained in the same manner as in Example 1 except that 100 parts by mass of the pressure-sensitive adhesive composition (a) was changed to 100 parts by mass of the pressure-sensitive adhesive composition (g).

(Example 6)

A pressure-sensitive adhesive sheet having a gel fraction of 50% was obtained in the same manner as in Example 1 except that 100 parts by mass of the pressure-sensitive adhesive composition (a) was changed to 100 parts by mass of the pressure-sensitive adhesive composition (h).

(Example 7)

A pressure-sensitive adhesive sheet having a gel fraction of 55% was obtained in the same manner as in Example 1 except that 100 parts by mass of the pressure-sensitive adhesive composition (a) was changed to 100 parts by mass of the pressure-sensitive adhesive composition (i).

(Comparative Example 1)

A pressure-sensitive adhesive sheet having a gel fraction of 60% was obtained in the same manner as in Example 1 except that 100 parts by mass of the pressure-sensitive adhesive composition (a) was changed to 100 parts by mass of the pressure-sensitive adhesive composition (c).

(Comparative Example 2)

A pressure-sensitive adhesive sheet having a gel fraction of 60% was obtained in the same manner as in Example 1 except that 100 parts by mass of the pressure-sensitive adhesive composition (a) was changed to 100 parts by mass of the pressure-sensitive adhesive composition (d).

(Comparative Example 3)

A pressure-sensitive adhesive sheet having a gel fraction of 60% was obtained in the same manner as in Example 1 except that 100 parts by mass of the pressure-sensitive adhesive composition (a) was changed to 100 parts by mass of the pressure-sensitive adhesive composition (e).

(Comparative Example 4)

0.1 part by mass of an isocyanate crosslinking agent (Coronate L-45, 45% by solid content, manufactured by Nippon Polyurethane Co., Ltd.) was added to 100 parts by mass of the pressure-sensitive adhesive composition (f) and stirred for 15 minutes. On a polyester film (hereinafter referred to as "# 75 release film ") having a thickness of 50 mu m after drying, and dried at 75 DEG C for 5 minutes. The obtained pressure-sensitive adhesive sheet and a polyester film (hereinafter referred to as # 38 release film) having a thickness of 38 탆 and one side of which was treated with a silicone compound were bonded. Thereafter, it was aged at 23 占 폚 for 7 days to obtain a substrate-less pressure-sensitive adhesive sheet having a thickness of 50 占 퐉 and a gel fraction of 70%.

(Comparative Example 5)

A pressure-sensitive adhesive sheet having a gel fraction of 80% was obtained in the same manner as in Example 1 except that 100 parts by mass of the pressure-sensitive adhesive composition (a) was replaced with 100 parts by mass of the pressure-sensitive adhesive composition (j) and 0.3 part by mass of an isocyanate-based crosslinking agent.

(Comparative Example 6)

A pressure-sensitive adhesive sheet having a gel fraction of 80% was obtained in the same manner as in Comparative Example 4 except that 100 parts by mass of the pressure-sensitive adhesive composition (f) was changed to 100 parts by mass of the pressure-sensitive adhesive composition (k) and 0.12 parts by mass of the isocyanate-based crosslinking agent.

With respect to the pressure-sensitive adhesive sheets obtained in the above Examples and Comparative Examples, the following evaluations were carried out. The obtained results are shown in Tables 1 and 2.

(White turbidity after leaving under high temperature and high humidity conditions)

The test sample prepared by bonding the pressure-sensitive adhesive sheet in the order of polyethylene terephthalate film and glass in this order was allowed to stand under the condition of 60 占 폚 and 90% RH for 250 hours and the haze immediately after the test sample was taken out under the above- HR-100 type " manufactured by SIGIGUJU KENKYU CHOJI.

O: 1.0% or less in haze

?: Haze 1.0% to 3.0%

×: Haze 3.0% or more

(Measurement of electric resistance value of indium tin oxide film)

(100 mu m) on one side of the pressure-sensitive adhesive sheet, cut into a size of 50 mm x 50 mm, and subjected to a bonding to the indium tin oxide film surface of a 100 mm x 100 mm indium tin oxide deposited polyethylene terephthalate film . The initial electrical resistance value (R1) was measured at both ends of the bonded adhesive sheet using "Loresta GP" manufactured by Mitsubishi Kagaku KK. The indium tin oxide deposited polyethylene terephthalate film in which the pressure-sensitive adhesive sheet was laminated was allowed to stand under the conditions of 60 ° C and 90% RH for 250 hours and left under the conditions of 23 ° C and 50% RH for 1 hour. R2) was measured. The rate of change of the electrical resistance value of the indium tin oxide (ITO) film was calculated by the following equation.

(%) Of the electrical resistance value of the ITO film = ((R2-R1) / R1) x100

O: Change rate of electric resistance value 90 to 110%

×: Electrical resistance value change rate less than 90% or 110% or more

(Evaluation of Print Step Followability 1)

A release film on one side of the prepared pressure sensitive adhesive sheet was peeled off and a polyethylene terephthalate film having a thickness of 100 占 퐉, a length of 50 mm and a width of 40 mm, in which a print layer having a thickness of 15 占 퐉 and a width of 5 mm was decorated in a liquid- . The peel-off film on one side of the obtained test piece was peeled off and laminated to a glass plate having a thickness of 1 mm, a length of 50 mm and a width of 40 mm, and subjected to heat and pressure treatment under conditions of 5 atm, 70 ° C and 20 minutes. After the heating and pressurizing treatment, the sheet was allowed to stand under 23 DEG C for one day, and the entire vicinity of the printed decorative portion was observed with a microscope (magnification: 300x) to confirm whether or not bubbles were mixed. The criteria for evaluation of air bubble incorporation are as follows.

○: No bubbles having a diameter of 5 μm or more

?: No air bubbles having a diameter of 30 占 퐉 or more

×: Bubbles having a diameter of 30 μm or more or peeling

[Table 1]

[Table 2]

The abbreviations in the table are as follows.

MEA: methoxyethyl acrylate

BA: butyl acrylate

2EHA: 2-ethylhexyl acrylate

HEA: Hydroxyethyl acrylate

MA: methyl methacrylate

AA: Acrylic acid

The release film on one side of the pressure-sensitive adhesive sheet prepared in Example 1 was peeled off, and the pressure-sensitive adhesive sheet was bonded to the surface of the polyethylene terephthalate film having no hard coating on the hard coating layer provided with the hard coating layer on one side thereof, Scattering-resistant pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one side thereof. With respect to the obtained anti-scattering adhesive sheet, the following evaluation was carried out. The obtained results are shown in Table 3.

(Evaluation of Print Step Followability 2)

The remaining one side release film of the obtained pressure-sensitive adhesive sheet was peeled off, and the print layer was laminated on a glass plate 1 mm thick, 50 mm long and 40 mm wide adorned with a liquid crystal, heated and pressed under conditions of 5 atm, Treatment. Immediately after the heating and pressurizing treatment, the entirety of the vicinity of the printed decorative part was observed with a microscope (magnification: 300 times), and it was confirmed whether or not bubbles were mixed. The criteria for evaluation of air bubble incorporation are as follows.

○: No bubbles having a diameter of 5 μm or more

?: No air bubbles having a diameter of 30 占 퐉 or more

×: Bubbles having a diameter of 30 μm or more or peeling

[Table 3]

As shown in the table, it was confirmed that the pressure-sensitive adhesive sheets of Examples 1 to 7 do not rise in haze and become opaque under high-temperature and high-humidity conditions even without a monomer containing a carboxyl group. In addition, the pressure-sensitive adhesive sheets of Examples 1 to 4 were excellent in followability to printing steps, and had good print step following ability even when a hard coating film provided with a hard coating layer was used as a base material. On the other hand, methoxyethyl acrylate having high hydrophilicity was used, but Comparative Example 1 using 2 ethylhexyl acrylate, Comparative Example 2 containing 49 mass% of n-butyl acrylate having 4 carbon atoms, In Comparative Example 3 containing no alkyl monomer and Comparative Example 5 having a low content of alkoxyalkyl acrylate monomer, the haze was elevated under high temperature and high humidity conditions, and cloudiness was observed. In the pressure-sensitive adhesive sheets of Comparative Example 4 and Comparative Example 6 having acrylic acid as the carboxyl group-containing monomer, the increase in the electric resistance value of ITO was confirmed although the opacity was not high under high temperature and high humidity conditions.

1, 1 ', 11, 21, 21' ... Adhesive sheet for metal side patch
2, 12, 22 ... Surface protection panel
3, 13, 23 ... Printing step
4, 4 '... ITO film
4a, 4a '... Transparent resin film
4b, 4b '... ITO
5, 17, 27 ... housing
6, 18, 28 ... Image display module
7, 19, 29 ... Adhesive member
14 ... ITO
15, 25 ... The pressure-
16, 26 ... Hard coating film
24 ... ITO glass
25a ... Clear glass
25b, 25c ... ITO

Claims (4)

A pressure-sensitive adhesive sheet laminated on a metal surface,
Wherein the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer comprising an acrylic pressure-sensitive adhesive using a (meth) acrylic acid ester copolymer,
Wherein the (meth) acrylic acid ester copolymer comprises a (meth) acrylic acid alkoxyalkyl ester monomer (A) and a (meth) acrylic acid alkyl ester (B) having an alkyl group having 1 to 4 carbon atoms as a monomer component,
(Meth) acrylic acid ester copolymer (A) in the monomer component constituting the (meth) acrylic acid ester copolymer is 50% by mass or more and 95% by mass or less, ) Acrylic acid alkyl ester (B) is 5 to 45% by mass,
Wherein the content of the carboxyl group-containing monomer in the monomer component constituting the (meth) acrylic acid ester copolymer is 0% by mass or more and 1% by mass or less. The method according to claim 1,
Wherein the (meth) acrylic acid alkyl ester (B) having an alkyl group of 1 to 4 carbon atoms is n-butyl acrylate. 3. The method according to claim 1 or 2,
Wherein the weight average molecular weight of the (meth) acrylic acid ester copolymer is from 300,000 to 1.6 million. 3. The method according to claim 1 or 2,
Wherein the pressure-sensitive adhesive layer has a gel fraction of 30 to 80% by mass.

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