KR102215674B1 - Double-sided pressure-sensitive adhesive sheet - Google Patents

Abstract

A double-sided adhesive sheet 1 used for bonding between a first hard body 4 and a second hard body 5, wherein the double-sided adhesive sheet 1 is adhered to the first hard body 4 It has an adhesive surface 11S and a second adhesive surface 12S adhered to the second hard body 5, and the adhesive force of the first adhesive surface 11S to the first hard body 4 is F1, When the adhesive force of the second adhesive surface 12S to the second hard body 5 is F2, the ratio of F1 to F2 (F1/F2) is 0.0001 to 0.1. This double-sided adhesive sheet 1 is excellent in rework property, and when peeling the first hard body 4 and the second hard body 5 bonded using the double-sided adhesive sheet 1, at least the first hard body It can be peeled so that the sieve 4 can be reused.

Description

Double-sided adhesive sheet {DOUBLE-SIDED PRESSURE-SENSITIVE ADHESIVE SHEET}

The present invention relates to a double-sided adhesive sheet used for bonding between a plurality of hard bodies.

BACKGROUND ART Various mobile electronic devices such as mobile phones and tablet terminals in recent years have a display using a display module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL) element, and the like.

In the above-described display, a polarizing film or the like is attached to a display module using a double-sided adhesive sheet, but there is a case where a shift occurs in the bonding position during this bonding. Here, since the display module is expensive, it is usually reused. Therefore, the adhesive sheet as described above is required to have a rework property that can be peeled off from the display module so that the display module can be reused. Therefore, Patent Documents 1 and 2 propose a double-sided pressure-sensitive adhesive sheet having rework property.

Japanese Patent Laid-Open No. 2004-231723 Japanese Patent Application Publication No. 2013-32483

In recent years, the display is often a touch panel type, in which case, a touch panel including a glass plate or a plastic plate is installed on the surface side of the display module. Even when these display module and touch panels are bonded, the use of double-sided pressure-sensitive adhesive sheets is increasing, but as described above, bonding of hard materials (hard bodies) with double-sided pressure-sensitive adhesive sheets is performed between films or films. It is more difficult than bonding the hard body, and the yield at the time of bonding is liable to decrease.

Accordingly, in the above case, although the need to peel the two hard bodies is higher so that the display module can be reused, it is very difficult to peel the two hard bodies bonded by the double-sided adhesive sheet. In the pressure-sensitive adhesive sheet disclosed in Patent Document 1, only the rework property in the case of peeling off the films or the film and the hard body is considered, and it is difficult to peel the two hard bodies. Further, the pressure-sensitive adhesive sheet disclosed in Patent Document 2 considers the case of peeling off two hard bodies, but its rework property is not sufficient.

The present invention is a double-sided adhesive sheet used for bonding between a first hard body and a second hard body provided for reuse, and is bonded using the adhesive layer. It is an object of the present invention to provide a double-sided pressure-sensitive adhesive sheet having excellent rework properties that can be peeled off so that the first hard body can be reused when the sieve and the second hard body are peeled.

In order to achieve the above object, the first aspect of the present invention is a double-sided adhesive sheet used for adhesion between a first hard body and a second hard body, wherein the double-sided adhesive sheet comprises the first hard body or the double-sided A first adhesive surface adhered to a member on the side of the first hard body than the adhesive sheet, and a second adhesive surface adhered to a member on the side of the second hard body than the second hard body or the double-sided adhesive sheet, , The adhesive force of the first adhesive surface to the member on the side of the first hard body than the first hard body or the double-sided adhesive sheet is F1, the second hard body side than the second hard body or the double-sided adhesive sheet A double-sided pressure-sensitive adhesive sheet is provided, wherein the ratio of F1 to F2 (F1/F2) is 0.0001 to 0.1 when the adhesive force of the second adhesive surface to the member is F2 (Invention 1).

The double-sided pressure-sensitive adhesive sheet according to the above invention (invention 1) is excellent in reworkability with respect to at least the first hard body by defining the adhesive force ratio as described above. Therefore, when peeling the 1st hard body and the 2nd hard body bonded using the said double-sided adhesive sheet, it can peel so that the 1st hard body can be reused at least.

In the above invention (invention 1), it is preferable that the double-sided pressure-sensitive adhesive sheet includes a first pressure-sensitive adhesive layer having the first pressure-sensitive adhesive surface and a second pressure-sensitive adhesive layer having the second pressure-sensitive adhesive surface (invention 2) .

In the above invention (invention 2), the ratio of the thickness of the first pressure-sensitive adhesive layer to the thickness of the second pressure-sensitive adhesive layer is preferably 0.01 to 10 (invention 3).

In the above invention (invention 2 and 3), it is preferable that a core material is provided between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer (invention 4).

In the above inventions (inventions 2 to 4), the first pressure-sensitive adhesive layer is preferably made of a silicone pressure-sensitive adhesive containing organopolysiloxane (invention 5).

In the above invention (invention 5), the silicone pressure-sensitive adhesive preferably contains an addition-type organopolysiloxane and an organopolysiloxane containing a trifunctional or tetrafunctional siloxane unit (invention 6).

In the above invention (invention 6), the addition-type organopolysiloxane is preferably obtained by reacting an organopolysiloxane having an alkenyl group and an organohydrogenpolysiloxane having a siloxane bond as a main skeleton (invention 7).

In the above inventions (inventions 2 to 7), it is preferable that the adhesive strength of the first pressure-sensitive adhesive layer on the first pressure-sensitive adhesive surface to a float glass according to JIS Z0237:2009 is 0.01 to 1 N/25 mm (invention 8).

In the above inventions (inventions 2 to 8), it is preferable that 100% modulus of the first pressure-sensitive adhesive layer is 0.3 to 1.5 MPa (invention 9).

In the above inventions (inventions 2 to 9), the second pressure-sensitive adhesive layer is preferably composed of an acrylic pressure-sensitive adhesive containing a (meth)acrylic acid ester polymer or an ultraviolet-curable pressure-sensitive adhesive (invention 10).

In the above invention (inventions 4 to 10), it is preferable that the core material is made of a polyester film (invention 11).

In the above inventions (Inventions 1 to 11), it is preferable that the first hard body is a display module (Invention 12).

In the above inventions (inventions 1 to 12), it is preferable that the second hard body is a cover material (inventions 13).

In the above inventions (Inventions 1 to 13), it is preferable that the first hard body and the second hard body are members constituting a touch panel (invention 14).

The double-sided adhesive sheet according to the present invention is excellent in rework property, and when peeling the first and second hard bodies bonded together using the double-sided adhesive sheet, at least the first hard body can be peeled off so that reuse is possible. have.

1 is a cross-sectional view of a double-sided adhesive sheet according to an embodiment of the present invention.
Fig. 2 is a cross-sectional view of a laminate in which a first hard body and a second hard body are bonded together using a double-sided adhesive sheet.
Fig. 3 is a plan view of a laminate produced by bonding a first hard body and a second hard body together with a double-sided pressure-sensitive adhesive sheet in Examples and Comparative Examples.

Hereinafter, an embodiment of the present invention will be described.

As shown in FIG. 1, the double-sided adhesive sheet 1 according to the present embodiment is sandwiched between the two release sheets 2a and 2b so as to contact the release surfaces of the two release sheets 2a and 2b. A laminate comprising the release sheet 2a, the double-sided adhesive sheet 1 and the release sheet 2b is hereinafter referred to as the double-sided adhesive sheet 3 with a release sheet.

In the present embodiment, the release sheets 2a and 2b are not essential constituent elements, and are peeled and removed when the double-sided pressure-sensitive adhesive sheet 1 is used. In addition, the peeling surface of a release sheet in this specification refers to the surface which has peelability in a peeling sheet, and includes both a peeling-treated surface and a surface exhibiting peelability even if no peeling treatment has been performed.

In the double-sided adhesive sheet 1 according to the present embodiment, as shown in FIG. 2, in a laminate 10 formed by laminating a first hard body 4 and a second hard body 5 provided for reuse. , It is used for adhesion between the first hard body 4 and the second hard body 5. This double-sided adhesive sheet 1 may be directly adhered to the first hard body 4 and/or the second hard body 5, and a member laminated on the side of the first hard body 4 and/or the second hard body It may be adhered to the member laminated on the side of the sieve 5. That is, in FIG. 2, the double-sided pressure-sensitive adhesive sheet 1 is directly adhered to the first hard body 4 and the second hard body 5 to directly bond both, but is not limited thereto.

In addition, the "hard body" in this specification means that the Young's modulus measured in conformity with JIS K7127:1999 is 10 GPa or more. The rigid body may be composed of a single layer or a single member, or may be composed of a plurality of layers or a plurality of members. In the latter case, it is one composed of a plurality of layers or a plurality of members, and if the Young's modulus is satisfied, even if some of the layers or members thereof do not satisfy the Young's modulus, it can be said to be a rigid body.

As shown in FIG. 2, the double-sided adhesive sheet 1 according to the present embodiment is a first hard body 4 than the double-sided adhesive sheet 1 in the first hard body 4 or the laminate 10 obtained. The first adhesive surface 11S adhered to the member on the) side (hereinafter sometimes referred to as the ``first hard body side member''), and the two sides in the second hard body 5 or the obtained laminate 10 It is provided with a 2nd adhesive surface 12S adhere|attached to the member which is on the 2nd hard body 5 side than the adhesive sheet 1 (it may be referred to as a "second hard body side member" hereafter).

In the double-sided adhesive sheet 1 of the present embodiment, the adhesive force of the first adhesive surface 11S to the hard body (for example, a glass plate) is F1, and the second adhesion to the hard body (for example, a glass plate). When the adhesive force of the surface 12S is F2, the ratio of F1 to F2 (F1/F2) is 0.0001 to 0.1, preferably 0.0003 to 0.08, particularly preferably 0.0005 to 0.05.

When the ratio of F1 to F2 is within the above range, when peeling the first hard body 4 and the second hard body 5 bonded using the double-sided adhesive sheet 1, the preparation of the double-sided adhesive sheet 1 1 The double-sided adhesive sheet 1 and the first hard body 4 are well separated at the interface between the adhesive surface 11S and the first hard body 4, so that the first hard body 4 or the second hard body ( 5) It does not break, and there is no residual adhesive on the first hard body 4. Thereby, at least the first hard body 4 can be reused. As described above, the double-sided pressure-sensitive adhesive sheet 1 in which the ratio of F1 to F2 is within the above range has excellent rework properties.

If the ratio of F1 to F2 is less than 0.0001, the adhesive force on the first adhesive surface 11S becomes too small, and the first adhesive surface 11S and the first hard body 4 are used when the laminate 10 is used, etc. ), unintended peeling occurs at the interface. On the other hand, if the ratio of F1 to F2 exceeds 0.1, the second hard body 5 is broken when the first hard body 4 and the second hard body 5 are peeled off, or the first hard body 4 The residual of the pressure-sensitive adhesive is caused to occur and cannot be peeled off so that the first hard body can be reused.

The double-sided adhesive sheet 1 may be composed of a first adhesive surface 11S and a second adhesive surface 12S so that the ratio of F1 to F2 falls within the above range, may be composed of a single layer, or may be composed of multiple layers. It may be made of a plurality of materials whose interlayers are not clear. From the viewpoint of ease of manufacture, the double-sided adhesive sheet 1 is a first adhesive layer 11 having a first adhesive surface 11S and a second adhesive surface 12S, as shown in FIGS. 1 and 2. It is preferable to have the 2 pressure-sensitive adhesive layer 12. Moreover, from the viewpoint of the handling property of the double-sided adhesive sheet 1, it is particularly preferable that the core material 13 is provided between the first adhesive layer 11 and the second adhesive layer 12. In addition, the 1st adhesive surface 11S is the surface opposite to the 2nd adhesive layer 12 in the 1st adhesive layer 11, The 2nd adhesive surface 12S is the 2nd adhesive layer 12 It is the surface opposite to the 1st adhesive layer 11 in ).

In addition, in the test examples described later, the rework property was evaluated while measuring the adhesive force using a glass plate as the hard body as an adherend, but it is considered that the same evaluation result is obtained even when other materials are used as the hard body as the adherend.

1. Double-sided adhesive sheet

(1) first adhesive layer

The first pressure-sensitive adhesive layer 11 may be composed of an adhesive in which the first adhesive surface 11S satisfies the above physical properties (ratio of F1 to F2), but specifically organopolysiloxane, in particular, addition-type organopolysiloxane It is preferably composed of a silicone pressure-sensitive adhesive containing a cured product). Such a silicone pressure-sensitive adhesive is likely to satisfy the above physical properties.

The addition-type organopolysiloxane is preferably obtained by reacting an organopolysiloxane having an alkenyl group and an organohydrogenpolysiloxane having a siloxane bond as a main skeleton.

The organopolysiloxane having a siloxane bond as a main skeleton and an alkenyl group is a compound represented by the following average unit formula (1), and is preferably a compound having at least two alkenyl groups in the molecule.

R ¹ _a SiO _(4-a)/2 ···(1)

(Wherein, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 8, which is identical to or different from each other, and a is 1.5 to 2.8, preferably 1.8 to 2.5. , More preferably an integer in the range of 1.95 to 2.05)

Examples of the unsubstituted or substituted monovalent hydrocarbon group bonded to the silicon atom represented by R ¹ include vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, octenyl group Alkenyl group, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, etc. Alkyl groups such as, phenyl groups, tolyl groups, xylyl groups, aryl groups such as naphthyl groups, aralkyl groups such as benzyl groups, phenylethyl groups, and phenylpropyl groups, and some or all of the hydrogen atoms of these groups are fluorine, bromine, chlorine, etc. Substituted with a halogen atom, a cyano group, or the like, such as a chloromethyl group, a chloropropyl group, a bromoethyl group, a trifluoropropyl group, and a cyanoethyl group. As the alkenyl group, a vinyl group is preferable from the viewpoint of short curing time and productivity.

Organohydrogenpolysiloxane has a SiH group in its molecule. When the alkenyl group of the organopolysiloxane reacts with the SiH group of the organohydrogenpolysiloxane, both are subjected to an addition reaction to obtain an addition-type organopolysiloxane.

Since the addition-type organopolysiloxane cures satisfactorily in the presence of a platinum catalyst, the silicone pressure-sensitive adhesive preferably contains a platinum catalyst. Examples of the platinum catalyst include platinum black, chlorinated platinum, chloroplatinic acid, a reaction product of chloroplatinic acid and monohydric alcohol, a complex of chloroplatinic acid and olefins, platinum bisacetoacetate, and the like.

The content of the platinum catalyst in the silicone pressure-sensitive adhesive is preferably 0.01 to 3 parts by mass, and particularly preferably 0.05 to 2 parts by mass, based on 100 parts by mass of the addition-type organopolysiloxane. When the content of the platinum catalyst is within the above range, the addition-type organopolysiloxane can be cured without interfering with coating to form the first pressure-sensitive adhesive layer 11.

In the addition-type organopolysiloxane, an organopolysiloxane (silicone resin) containing a trifunctional or tetrafunctional siloxane unit in a molecule can be contained in order to increase adhesive strength within a range that does not impair the object of the present invention.

The content of the organopolysiloxane containing trifunctional or tetrafunctional siloxane units in the silicone pressure-sensitive adhesive is preferably 10 to 200 parts by mass, and particularly 15 to 100 parts by mass based on 100 parts by mass of the addition type organopolysiloxane. It is preferable, and further, it is preferable that it is 20-80 mass parts. When the content of the organopolysiloxane containing a trifunctional or tetrafunctional siloxane unit is too large, the adhesive strength of the first pressure-sensitive adhesive layer 11 may increase and the rework property may decrease.

The thickness of the first pressure-sensitive adhesive layer 11 is preferably 5 to 50 µm, particularly preferably 10 to 40 µm, and further preferably 15 to 35 µm. When the thickness of the first pressure-sensitive adhesive layer 11 is 5 μm or more, a desired adhesive strength can be exhibited. Further, since the thickness of the first pressure-sensitive adhesive layer 11 is 50 μm or less, mixing of residual solvents or air bubbles resulting from the manufacturing process is effectively prevented, and stability of adhesive force and optical properties can be excellent.

In order to form the first pressure-sensitive adhesive layer 11, for example, an addition-type organopolysiloxane, an organopolysiloxane containing trifunctional or tetrafunctional siloxane units as desired, and a platinum catalyst, methyl ethyl ketone, toluene. , A coating solution diluted to about 10 to 60% by mass with a solvent such as ethyl acetate or xylene is applied to an object to be applied (for example, the core material 13) and heated to cure. The heating temperature is preferably about 90 to 180°C, and the heating time is preferably about 1 to 5 minutes.

Here, the adhesive strength of the first adhesive layer 11 on the first adhesive surface 11S to the float glass according to JIS Z0237:2009 is preferably 0.01 to 1 N/25 mm, and particularly 0.015 to 0.7 N/ It is preferably 25 mm, and more preferably 0.02 to 0.5 N/25 mm. If the adhesive strength is 0.01N/25mm or more, it is possible to prevent unintended peeling at the interface between the first adhesive surface 11S and the first hard body 4 when using the laminate 10, etc. . Moreover, when the said adhesive force is 1 N/25 mm or less, peelability of the 1st adhesive layer 11 with respect to an adherend is maintained satisfactorily, and excellent rework property is exhibited. In addition, the specific measuring method of the said adhesive force is as shown in the test example mentioned later.

The 100% modulus of the first pressure-sensitive adhesive layer 11 is preferably 0.3 to 1.5 MPa, particularly preferably 0.4 to 1.2 MPa, and further preferably 0.5 to 1.0 MPa. When the 100% modulus is 0.3 MPa or more, the adhesion of the first pressure-sensitive adhesive layer 11 to the adherend is maintained satisfactorily. Moreover, when the 100% modulus is 1.5 MPa or less, when attaching the 1st adhesive layer 11 to an adherend, it can suppress that air enters between them.

(2) 2nd adhesive layer

The second adhesive layer 12 may be composed of an adhesive in which the second adhesive surface 12S satisfies the above physical properties (ratio of F1 to F2), but specifically, an acrylic adhesive containing a (meth)acrylic acid ester polymer. Or, it is preferably composed of an ultraviolet curable adhesive. Such an adhesive is easy to satisfy the above physical properties.

The acrylic pressure-sensitive adhesive contains a (meth)acrylic acid ester polymer (a), and preferably contains the (meth)acrylic acid ester polymer (a) crosslinked with a crosslinking agent (b). In addition, in this specification, (meth)acrylic acid ester means both acrylic acid ester and methacrylic acid ester. Other similar terms are the same. In addition, the concept of "copolymer" is also included in "polymer". Further, it is preferable that the (meth)acrylic acid ester polymer (a) does not have an ultraviolet curable group from the viewpoint of facilitating adjustment of the adhesive force.

It is preferable that the (meth)acrylic acid ester polymer (a) contains an alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group as a monomer constituting the polymer. Thereby, the obtained adhesive can express preferable adhesiveness. In addition, the (meth)acrylic acid ester polymer (a) includes a (meth)acrylate alkyl ester having 1 to 20 carbon atoms in the alkyl group, a monomer having a functional group reacting with the crosslinking agent (b) (reactive functional group-containing monomer), as desired. It is particularly preferred that it is a copolymer of other monomers used accordingly.

Examples of the alkyl (meth)acrylate ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and n (meth)acrylate. -Pentyl, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myrisyl (meth)acrylate , Palmityl (meth)acrylate, stearyl (meth)acrylate, and the like. Among them, from the viewpoint of further improving the adhesiveness, (meth)acrylate esters having 1 to 8 carbon atoms in the alkyl group are preferable, and methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate This is particularly preferred. In addition, these may be used individually or may be used in combination of 2 or more types.

The (meth)acrylic acid ester polymer (a) preferably contains 40 to 99% by mass of an alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer, and particularly 50 to 90 It is preferable to contain it by mass %, and it is preferable to contain it further 60 to 80 mass %.

As the reactive functional group-containing monomer, a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), etc. are preferably mentioned. These may be used alone or in combination of two or more.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and (meth)acrylate. )(Meth)acrylate hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth)acrylate. Among them, from the viewpoint of reactivity of the hydroxyl group in the obtained (meth)acrylic acid ester polymer (a) with the crosslinking agent (b) and copolymerization with other monomers, 2-hydroxyethyl (meth)acrylate and 4-hydroxyethyl (meth)acrylic acid. Hydroxybutyl is preferred. These may be used alone or in combination of two or more.

As a carboxyl group-containing monomer, ethylenically unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid, are mentioned, for example. Among them, acrylic acid is preferable from the viewpoint of reactivity of the carboxyl group in the obtained (meth)acrylic acid ester polymer (a) with the crosslinking agent (b) and copolymerization with other monomers. These may be used alone or in combination of two or more.

As an amino group-containing monomer, aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. are mentioned, for example. These may be used alone or in combination of two or more.

The (meth)acrylic acid ester polymer (a) is a monomer unit constituting the polymer, preferably containing 1 to 40% by mass of a reactive functional group-containing monomer, particularly preferably 10 to 35% by mass, and further It is preferable to contain 20-30 mass %.

Examples of the other monomers include (meth)acrylate alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, and (meth)acrylate esters having an aliphatic ring such as cyclohexyl (meth)acrylate. , Acrylamide, non-crosslinkable acrylamide such as methacrylamide, (meth)acrylic acid N,N-dimethylaminoethyl, (meth)acrylic acid N,N-dimethylaminopropyl, etc. ) Acrylic acid ester, vinyl acetate, styrene, and the like. These may be used alone or in combination of two or more.

The polymerization aspect of the (meth)acrylic acid ester polymer (a) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth)acrylic acid ester polymer (a) is preferably 100,000 to 2.2 million, particularly preferably 200,000 to 1.8 million, and further preferably 400,000 to 1.6 million. In addition, the weight average molecular weight in this specification is a value in terms of polystyrene measured by a gel permeation chromatography (GPC) method.

Moreover, in the said acrylic adhesive, (meth)acrylic acid ester polymer (a) may be used individually by 1 type, and may be used in combination of 2 or more types.

As the crosslinking agent (b), any one that reacts with the reactive functional group possessed by the (meth)acrylic acid ester polymer (a) may be used. For example, an isocyanate crosslinking agent, an epoxy crosslinking agent, an amine crosslinking agent, a melamine crosslinking agent, an aziridine crosslinking agent, and hydrazine A crosslinking agent, an aldehyde type crosslinking agent, an oxazoline type crosslinking agent, a metal alkoxide type crosslinking agent, a metal chelate type crosslinking agent, a metal salt type crosslinking agent, an ammonium salt type crosslinking agent, and the like. Among the above, when the reactive functional group of the (meth)acrylic acid ester polymer (a) is a hydroxyl group, it is preferable to use an isocyanate crosslinking agent having excellent reactivity with a hydroxyl group, and the reactive functional group possessed by the (meth)acrylic acid ester polymer (a) When is a carboxyl group, it is preferable to use an epoxy-based crosslinking agent excellent in reactivity with a carboxyl group. Further, the crosslinking agent (b) may be used alone or in combination of two or more.

The isocyanate crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate. Adducts that are reactants with low-molecular active hydrogen-containing compounds such as alicyclic polyisocyanates such as, and their biuret body, isocyanurate body, and further ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc. Sieves and the like. Among them, from the viewpoint of reactivity with a hydroxyl group, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferred.

As an epoxy crosslinking agent, for example, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, Ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidylamine, etc. are mentioned.

The amount of the crosslinking agent (b) used is preferably 0.001 to 10 parts by mass, particularly preferably 0.01 to 1 parts by mass, and further preferably 0.05 to 0.5 parts by mass based on 100 parts by mass of the (meth)acrylic acid ester polymer (a). Do.

When the adhesive composition containing the (meth)acrylic acid ester polymer (a) containing a reactive functional group-containing monomer and the crosslinking agent (b) as a monomer unit constituting the polymer is heated, the crosslinking agent (b) is a (meth)acrylic acid ester polymer It reacts with the reactive functional group of the reactive functional group-containing monomer constituting (a). Thereby, a structure in which the (meth)acrylic acid ester polymer (a) is crosslinked by the crosslinking agent (b) is formed, and the cohesive strength of the obtained pressure-sensitive adhesive layer, and furthermore, strength and durability are improved.

To the acrylic pressure-sensitive adhesive, various additives commonly used as desired, for example, a refractive index adjuster, an antistatic agent, a tackifier, a silane coupling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a softener, a filler, and the like may be added.

As the ultraviolet-curable pressure-sensitive adhesive, one containing a (meth)acrylic acid ester polymer having ultraviolet curability, or one containing a (meth)acrylic acid ester polymer and ultraviolet-curable compound having no ultraviolet curability, and in particular, a photopolymerization initiator is added. It is preferable to contain as.

As the (meth)acrylic acid ester polymer having ultraviolet curing properties, an adduct acrylate polymer in which a group having a (meth)acryloyl group is introduced into the side chain is preferable. Such an adduct acrylate-based polymer uses a copolymer of a (meth)acrylic acid ester and a monomer having a crosslinkable functional group in the molecule, and a (meth)acryloyl group and crosslinkability are formed in part of the crosslinkable functional group of the copolymer. It can be obtained by reacting a compound having a group that reacts with a functional group.

As the ultraviolet-curable compound, a polyfunctional acrylate-based oligomer having a weight average molecular weight of 50,000 or less or a polyfunctional acrylate-based monomer having a molecular weight of 1000 or less is preferable.

The thickness of the second adhesive layer 12 is preferably 5 to 300 µm, particularly preferably 10 to 200 µm, and further preferably 15 to 150 µm. When the thickness of the 2nd adhesive layer 12 is 5 micrometers or more, a desired adhesive force can be exhibited. Moreover, when the thickness of the 2nd adhesive layer 12 is 300 micrometers or less, the obtained laminated body can be prevented from becoming excessively thick.

The ratio of the thickness of the first pressure-sensitive adhesive layer 11 to the thickness of the second pressure-sensitive adhesive layer 12 is preferably 0.01 to 10, particularly preferably 0.05 to 5, and further preferably 0.1 to 3. . When the ratio of the thicknesses of both is within the above range, it becomes easy to satisfy the physical properties (ratio of F1 to F2), and the rework property of the double-sided adhesive sheet 1 is more excellent.

When the second pressure-sensitive adhesive layer 12 is composed of an acrylic pressure-sensitive adhesive, in order to form the second pressure-sensitive adhesive layer 12, a coating solution containing an acrylic pressure-sensitive adhesive and a solvent as desired is applied to the target (for example, the release sheet 2b ), and heat treatment to form a coating film. When the curing period is not necessary, the formed coating film becomes the second pressure-sensitive adhesive layer 12 as it is, and when the curing period is required, it becomes the second pressure-sensitive adhesive layer 12 after the curing period has elapsed.

The heat treatment can also serve as a drying treatment when volatilizing a diluted solvent or the like of the coating solution. When performing heat treatment, the heating temperature is preferably 50 to 150°C, and particularly preferably 70 to 120°C. Further, the heating time is preferably 30 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes. After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be set at room temperature (eg, 23° C., 50% RH).

When the acrylic pressure-sensitive adhesive contains a (meth)acrylic acid ester polymer (a) having a reactive functional group and a crosslinking agent (b), the (meth)acrylic acid ester polymer (a) is crosslinked by the crosslinking agent (b) by the heat treatment. Structure is formed.

On the other hand, when the second pressure-sensitive adhesive layer 12 is composed of an ultraviolet-curable pressure-sensitive adhesive, in order to form the second pressure-sensitive adhesive layer 12, a coating solution containing an ultraviolet-curable pressure-sensitive adhesive and a solvent as desired is applied to the target (for example, For example, it is applied to the peeling surface of the peeling sheet 2b) and heat-treated to form a coating film. After that, ultraviolet rays are irradiated to the coating film to cure the ultraviolet curable pressure-sensitive adhesive to form the second pressure-sensitive adhesive layer 12.

Here, the adhesive force of the second adhesive layer 12 on the second adhesive surface 11S to the float glass according to JIS Z0237:2009 is preferably 1 to 50 N/25 mm, and particularly 2 to 40 N/25 It is preferable that it is mm, and further it is preferable that it is 5-30N/25mm. When the adhesive force is 1N/25 mm or more, it is possible to prevent unintended peeling at the interface between the second adhesive surface 12S and the second hard body 5 when using the laminate 10 or the like. On the other hand, when the adhesive force exceeds 50 N/25 mm, when the second hard body 5 also wants to be reused, the adhesive remains on the side of the second hard body 5 and cannot be reused.

(3) heartwood

The core material 13 imparts rigidity to the double-sided adhesive sheet 1 to improve the handling properties of the double-sided adhesive sheet 1. It is preferable that this core material 13 is comprised from a plastic film. Examples of plastic films include polyester films made of polyester such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyurethane films, polyethylene films, polypropylene films, and cellulose films such as triacetylcellulose. , Polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, acrylic resin film, norbornene resin film, and plastic film such as cycloolefin resin film ; And laminates of two or more of these. The plastic film may be uniaxially stretched or biaxially stretched. Among these, a polyester film is preferable, and a polyethylene terephthalate film is particularly preferable.

In the core material 13 made of the plastic film as described above, for the purpose of improving adhesion with the adjacent first adhesive layer 11 and/or the second adhesive layer 12, one or both sides as desired. For example, surface treatment or primer treatment by an oxidation method or the like can be performed. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, and ultraviolet irradiation treatment. These surface treatment methods are appropriately selected depending on the type of the plastic film, but in general, the corona discharge treatment method is preferably used from the viewpoint of effect and operability.

The thickness of the core material 13 is preferably 2 to 250 µm, particularly preferably 5 to 125 µm, and further preferably 10 to 75 µm, from the viewpoint of improving the handling properties of the double-sided adhesive sheet 1 Do.

2. Release sheet

The release sheet 2a, 2b is not particularly limited, and a known plastic film can be used. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate Film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin Film or the like is used. Moreover, these crosslinked films are also used. Moreover, these laminated films may be sufficient.

It is preferable that the peeling surface (especially the surface in contact with the double-sided adhesive sheet 1) of the peeling sheets 2a and 2b is subjected to a peeling treatment (however, when the adhesive layer 11 is a silicone adhesive, peeling treatment It is also preferable to use the plastic film which has not been applied as it is). Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. In addition, it is preferable to use one of the release sheets 2a and 2b as a medium-release type release sheet having a high peeling force, and the other release sheet as a light release type release sheet having a small peeling force.

The thickness of the release sheets 2a and 2b is not particularly limited, but is usually about 20 to 150 µm.

3. Preparation of double-sided adhesive sheet with release sheet attached

As an example of manufacture of the double-sided pressure-sensitive adhesive sheet 3 with a release sheet attached, after forming the first pressure-sensitive adhesive layer 11 on one side of the core material 13, the release sheet 2a on the exposed surface of the pressure-sensitive adhesive layer 11 ) Are laminated so that the peeling surface is in contact, and this is referred to as a first laminate. On the other hand, the second adhesive layer 12 is formed on the release surface of the release sheet 2b, and this is referred to as a second laminate. Next, the first laminate and the second laminate are bonded to each other so that the core material 13 of the first laminate and the second pressure sensitive adhesive layer 12 of the second laminate overlap, and the double-sided pressure-sensitive adhesive sheet 3 with a release sheet attached thereto. ).

4. Use of double-sided adhesive sheet

The laminated body 10 shown in FIG. 2 is obtained by bonding the first hard body 4 and the second hard body 5 provided for reuse using the double-sided adhesive sheet 1. That is, the laminated body 10 is comprised of the 1st hard body 4, the 2nd hard body 5, and the double-sided adhesive sheet 1 interposed between them.

The double-sided adhesive sheet 1 in this embodiment is provided with the first adhesive layer 11, the core material 13, and the second adhesive layer 12, and the agent in the first adhesive layer 11 1 adhesive surface 11S is adhered to the first hard body 4, and the second adhesive surface 12S in the second adhesive layer 12 is adhered to the second hard body 5 .

As the first hard body 4 provided for reuse, an expensive member, specifically, a display body module, a solar cell module, and the like can be mentioned. As a display module, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, electronic paper, etc. are mentioned, for example. Further, on the side of the double-sided adhesive sheet 1 of this display module, various functional layers (transparent conductive films, etc.) may be formed.

The material of the portion in contact with the double-sided pressure-sensitive adhesive sheet 1 in the above member is usually a glass plate, a plastic plate, a metal plate, a semiconductor plate, and the like, and preferably a glass plate.

Moreover, as the 2nd hard body 5, a glass plate, a plastic plate, a metal plate, a semiconductor plate, or their laminated body etc. are mentioned, for example, Preferably it is a glass plate.

It does not specifically limit as said glass plate, For example, chemically strengthened glass, alkali free glass, quartz glass, soda-lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, etc. are mentioned. have. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

The plastic plate is not particularly limited, and examples thereof include an acrylic plate made of polymethyl methacrylate, or a polycarbonate plate. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

In addition, various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, anti-glare layer, etc.) may be formed on one or both surfaces of the glass plate or plastic plate, or metal wiring may be formed, and an optical member May be laminated.

As said optical member, for example, a polarizing plate (polarizing film), a polarizer, a retardation plate (phase difference film), a viewing angle compensation film, a brightness improving film, a contrast improving film, a liquid crystal polymer film, a diffusion film, a hard coat film, a semi-transmissive reflective film And the like.

In order to manufacture the laminate 10, as an example, first, one release sheet 2b of the double-sided adhesive sheet 3 to which the release sheet is attached is peeled, and the exposed second adhesive layer 12 and the second hard The sieve (5) is bonded together. Next, the other release sheet 2a is peeled from the double-sided adhesive sheet 3 with the release sheet attached, and the exposed first adhesive layer 11 and the first hard body 4 are attached.

In the laminated body 10 manufactured as described above, when a shift occurs in the bonding position, it is necessary to peel the first hard body 4 and the second hard body 5. When the 1st hard body 4 and the 2nd hard body 5 are peeled in this laminated body 10, the 1st adhesive surface 11S of the double-sided adhesive sheet 1 (the 1st adhesive layer 11) The double-sided adhesive sheet 1 (first adhesive layer 11) and the first hard body 4 are well separated at the interface between the first hard body 4 and the first hard body 4 or the second hard body 4 The hard body 5 does not break or the adhesive remains in the first hard body 4. Thereby, at least the first hard body 4 can be reused. In this way, the double-sided pressure-sensitive adhesive sheet 1 according to the present embodiment is very excellent in rework property.

It is preferable that the laminated body 10 in this embodiment is a touch panel, especially a capacitive touch panel, and therefore, the first hard body 4 and the second hard body 5 constitute a touch panel. It is preferable that it is absent. In this case, the first hard body 4 is preferably a display module or a member including a display module, and the second hard body 5 is a cover material made of a glass plate or a plastic plate, or a member including a cover material. It is preferable to be. The second hard body 5 may be a cover material integrated sensor (OGS: One Glass Solution) in which a sensor function is formed in the cover material (a circuit of a transparent conductive film is formed in the cover material).

Although not shown in FIG. 2, between the double-sided adhesive sheet 1 and the first hard body 4 and/or between the double-sided adhesive sheet 1 and the second hard body 5 in the laminate 10 , One or multiple layers of the film sensor for a touch panel may be formed. Further, a desired pressure-sensitive adhesive layer may be formed between the plurality of film sensors. The film sensor is made of, for example, a base film and a transparent conductive film made of patterned tin-doped indium oxide (ITO).

Embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents falling within the technical scope of the present invention.

For example, either one of the release sheets 2a and 2b in the double-sided pressure-sensitive adhesive sheet 3 with a release sheet may be omitted. Moreover, another member may exist between the double-sided adhesive sheet 1 and the 1st hard body in the laminated body 10, and/or between the double-sided adhesive sheet 1 and the 2nd hard body.

Example

Hereinafter, the present invention will be described more specifically by examples and the like, but the scope of the present invention is not limited to these examples.

[Production Example 1]

Additive type organopolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., brand name: KS-847H) 100 parts by mass (solid content conversion value; the same below) consisting of organopolysiloxane and organohydrogenpolysiloxane having a siloxane bond as the main skeleton and having a vinyl group. And, 20 parts by mass of organopolysiloxane (silicone resin; manufactured by Toray Dow Corning, brand name: SD-4584) containing trifunctional or tetrafunctional siloxane units, and 20 parts by weight of platinum catalyst (manufactured by Toray Dow Corning, brand name: SRX-212 ) 1.5 parts by mass was mixed, stirred sufficiently, and diluted with methyl ethyl ketone to obtain a pressure-sensitive adhesive coating liquid.

The obtained pressure-sensitive adhesive coating solution was applied to one side of a polyethylene terephthalate (PET) film (manufactured by Toyobo, PET A4300, thickness: 38 μm) as a core material with a knife coater so that the thickness after drying became 25 μm, and then 120 It heat-processed at degreeC for 2 minutes, and the adhesive layer (silicon adhesive layer A) which consists of a silicone adhesive was formed. Thereafter, the adhesive surface of the silicone pressure-sensitive adhesive layer A was protected with an untreated PET film (manufactured by Toray Corporation, T60, thickness: 50 µm) as a release sheet to which no release treatment or easy adhesion treatment was applied.

[Production Example 2]

Additive type organopolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., brand name: KS-847H) 100 parts by mass and trifunctional or tetrafunctional consisting of organopolysiloxane and organohydrogenpolysiloxane having a siloxane bond as the main skeleton and having a vinyl group 50 parts by mass of organopolysiloxane (silicone resin; manufactured by Toray Dow Corning, brand name: SD-4584) and 1.5 parts by mass of platinum catalyst (manufactured by Toray Dow Corning, brand name: SRX-212) are mixed and sufficiently The mixture was stirred and diluted with methyl ethyl ketone to obtain a pressure-sensitive adhesive coating liquid.

The obtained pressure-sensitive adhesive coating liquid was applied to one side of a polyethylene terephthalate film (manufactured by Toyobo, PET A4300, thickness: 38 μm) as a core material with a knife coater so that the thickness after drying became 25 μm, and then 2 at 120° C. It heat-processed for a minute, and the adhesive layer (silicon adhesive layer B) which consists of a silicone adhesive was formed. Thereafter, the adhesive surface of the silicone pressure-sensitive adhesive layer B was protected with an untreated PET film (manufactured by Toray Corporation, T60, thickness: 50 µm) as a release sheet to which no peeling treatment or easy-adhesion treatment was applied.

[Production Example 3]

90 parts by mass of n-butyl acrylate (BA) and 10 parts by mass of acrylic acid (AA) were copolymerized to prepare a (meth)acrylic acid ester polymer. When the molecular weight of this (meth)acrylic acid ester polymer was measured by the method described later, it was a weight average molecular weight of 500,000.

100 parts by mass of the (meth)acrylic acid ester polymer obtained in the above step and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., TERAD-C) as an epoxy crosslinking agent ) 0.05 parts by mass was mixed, stirred sufficiently, and diluted with ethyl acetate to obtain a pressure-sensitive adhesive coating liquid.

The obtained pressure-sensitive adhesive coating liquid was applied to the peeling-treated surface of a release sheet (manufactured by Lintec, SP-PET3811, thickness: 38 µm) obtained by removing one side of a polyethylene terephthalate film with a silicone-based release agent, so that the thickness after drying was 25 µm. After coating with a coater, heat treatment was performed at 90° C. for 1 minute to form an adhesive layer (acrylic adhesive layer A) made of an acrylic adhesive.

[Production Example 4]

The pressure-sensitive adhesive coating liquid obtained in Preparation Example 3 was applied to the peeling-treated surface of a release sheet (manufactured by Lintec, SP-PET3811, thickness: 38 μm) obtained by peeling off one side of a polyethylene terephthalate film with a silicone-based release agent, and the thickness after drying was 50 After application|coating with a knife coater so that it might become micrometer, it heat-processes at 90 degreeC for 2 minutes, and the adhesive layer (acrylic adhesive layer A') which consists of an acrylic adhesive was formed.

[Production Example 5]

60 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl acrylate (MA), and 20 parts by mass of 2-hydroxyethyl acrylate (HEA) were copolymerized to prepare a (meth)acrylic acid ester polymer. When the molecular weight of this (meth)acrylic acid ester polymer was measured by the method described later, it was a weight average molecular weight of 600,000.

100 parts by mass of the (meth)acrylic acid ester polymer obtained in the above step and 0.2 parts by mass of trimethylolpropane-modified tolylene diisocyanate (TDI; manufactured by Soken Chemical Co., Ltd., L-45) as an isocyanate-based crosslinking agent were mixed, sufficiently stirred, and ethyl acetate By diluting with, an adhesive coating liquid was obtained.

The obtained pressure-sensitive adhesive coating liquid was applied to the peeling-treated surface of a release sheet (manufactured by Lintec, SP-PET3811, thickness: 38 µm) obtained by removing one side of a polyethylene terephthalate film with a silicone-based release agent, so that the thickness after drying was 25 µm. After coating with a coater, heat treatment was performed at 90° C. for 1 minute to form an adhesive layer (acrylic adhesive layer B) made of an acrylic adhesive.

[Production Example 6]

70 parts by mass of 2-ethylhexyl acrylate (2EHA), 10 parts by mass of methyl methacrylate (MA), and 20 parts by mass of 2-hydroxyethyl acrylate (HEA) were copolymerized to prepare a (meth)acrylic acid ester polymer. When the molecular weight of this (meth)acrylic acid ester polymer was measured by the method described later, it was 600,000 in weight average molecular weight.

100 parts by mass of the (meth)acrylic acid ester polymer obtained in the above step and 0.2 parts by mass of trimethylolpropane-modified tolylene diisocyanate (TDI; manufactured by Soken Chemical Co., Ltd., L-45) as an isocyanate-based crosslinking agent were mixed, sufficiently stirred, and ethyl acetate By diluting with, an adhesive coating liquid was obtained.

The obtained pressure-sensitive adhesive coating liquid was applied to the peeling-treated surface of a release sheet (manufactured by Lintec, SP-PET3811, thickness: 38 µm) obtained by removing one side of a polyethylene terephthalate film with a silicone-based release agent, so that the thickness after drying was 25 µm. After coating with a coater, heat treatment was performed at 90° C. for 1 minute to form an adhesive layer (acrylic adhesive layer C) made of an acrylic adhesive.

[Production Example 7]

99 parts by mass of n-butyl acrylate (BA) and 1 part by mass of 4-hydroxybutyl acrylate (4HBA) were copolymerized to prepare a (meth)acrylic acid ester polymer. When the molecular weight of this (meth)acrylic acid ester polymer was measured by the method described later, it was 1.5 million in weight average molecular weight.

100 parts by mass of the (meth)acrylic acid ester polymer obtained in the above step and 0.15 parts by mass of trimethylolpropane-modified xylylene diisocyanate (XDI; manufactured by Soken Chemical Co., Ltd., TD-75) as an isocyanate-based crosslinking agent were mixed, sufficiently stirred, and acetic acid By diluting with ethyl, an adhesive coating liquid was obtained.

The obtained pressure-sensitive adhesive coating liquid was applied to the peeling-treated surface of a release sheet (manufactured by Lintec, SP-PET3811, thickness: 38 μm) in which one side of a polyethylene terephthalate film was peeled off with a silicone-based release agent, so that the thickness after drying was 25 μm. After coating with a knife coater, heat treatment was performed at 90° C. for 1 minute to form an adhesive layer (acrylic adhesive layer D) made of an acrylic adhesive.

[Production Example 8]

85 parts by mass of n-butyl acrylate (BA) and 15 parts by mass of acrylic acid (AA) were copolymerized to prepare a (meth)acrylic acid ester polymer. When the molecular weight of this (meth)acrylic acid ester polymer was measured by the method described later, it was a weight average molecular weight of 500,000.

100 parts by mass of the (meth)acrylic acid ester polymer obtained in the above step and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., TERAD-C) as an epoxy crosslinking agent ) 0.05 parts by mass was mixed, stirred sufficiently, and diluted with ethyl acetate to obtain a pressure-sensitive adhesive coating liquid.

The obtained pressure-sensitive adhesive coating liquid was applied to the peeling-treated surface of a release sheet (manufactured by Lintec, SP-PET3811, thickness: 38 µm) obtained by removing one side of a polyethylene terephthalate film with a silicone-based release agent, so that the thickness after drying was 25 µm. After coating with a coater, heat treatment was performed at 90° C. for 1 minute to form an adhesive layer (acrylic adhesive layer E) made of an acrylic adhesive.

Table 1 shows the composition of the pressure-sensitive adhesive (subject) prepared in each preparation example, the weight average molecular weight (Mw) of the (meth)acrylic acid ester polymer, the type and amount of the crosslinking agent, and the thickness of the pressure-sensitive adhesive layer.

Here, the above-described weight average molecular weight (Mw) is a weight average molecular weight in terms of polystyrene measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).

<Measurement conditions>

GPC measuring device: manufactured by Tosoh Corporation, HLC-8020

GPC column (passed in the following order): manufactured by Tosoh Corporation

TSK guard column HXL-H

TSK gel GMHXL(×2)

TSK gel G2000HXL

Measurement solvent: tetrahydrofuran

·Measurement temperature: 40℃

[Example 1]

As the first pressure-sensitive adhesive layer, on the surface of the PET film (core material) side of the laminate made of the PET film (core material)/silicone pressure-sensitive adhesive layer A/untreated PET film (release sheet) obtained in Production Example 1, prepared as a second pressure-sensitive adhesive layer The acrylic adhesive layer A formed in Example 3 was affixed. The obtained laminate was cut into a width of 25 mm x a length of 200 mm, and a release sheet/acrylic adhesive layer A (second adhesive layer)/PET film (core material)/silicone adhesive layer A (first adhesive layer)/untreated PET film ( A double-sided pressure-sensitive adhesive sheet with a release sheet consisting of a release sheet) was obtained.

The release sheet on the side of the first pressure-sensitive adhesive layer was peeled from the double-sided pressure-sensitive adhesive sheet to which the obtained release sheet was attached, and the exposed silicone pressure-sensitive adhesive layer A was the first hard body, soda lime glass (manufactured by Central Glass, thickness: 1.1 mm, Young's modulus: 71 GPa; The said double-sided adhesive sheet was affixed to the said 1st hard body so that the said double-sided adhesive sheet may protrude in the longitudinal direction so that it may contact 4) in FIG.

Subsequently, the release sheet on the side of the second pressure-sensitive adhesive layer was peeled from the double-sided pressure-sensitive adhesive sheet, and soda lime glass (manufactured by Central Glass, thickness: 1.1 mm , Young's modulus: 71 GPa; reference numeral 5) in Fig. 3 were bonded together. At this time, the second hard body was bonded to the double-sided adhesive sheet so that the end portion in the longitudinal direction of the double-sided adhesive sheet on the first hard body and the end portion in the longitudinal direction of the second hard body became the same position ( 3). In this way, soda lime glass (second hard body)/acrylic adhesive layer A (second adhesive layer)/PET film (core material)/silicone adhesive layer A (first adhesive layer)/soda lime glass (first hard body) ) To obtain a laminate.

In addition, in this embodiment, from the viewpoint of the ease of adjusting the attachment position by hand, the silicone adhesive layer A was first affixed to the first hard body, but when industrial production was considered, the second hard body and the acrylic adhesive layer A were first pasted. It may be combined, and then the silicone pressure-sensitive adhesive layer A and the first hard body may be bonded together.

[Examples 2 to 11, Comparative Examples 1 to 2]

As shown in Table 2, in the same manner as in Example 1, except for changing the first adhesive layer, the second adhesive layer, the first hard body, and the second hard body, the second hard body / the second adhesive layer / the core / A laminate made of the first pressure-sensitive adhesive layer/first hard body was produced. However, in Comparative Examples 1 and 2, by attaching the laminate of the acrylic pressure-sensitive adhesive layer/release sheet obtained in Production Example on both surfaces of the PET film (manufactured by Toyobo, PET A4300; thickness 38 μm) serving as the core material, the release sheet/ Acryl adhesive layer B or D/PET film (core material) / acrylic adhesive layer A / obtaining a double-sided adhesive sheet with a release sheet consisting of a peeling sheet, and using the double-sided adhesive sheet, a second hard body / a second adhesive layer A laminate made of /core material/first adhesive layer/first hard body was produced.

Here, in Example 10, a chemically strengthened glass plate (manufactured by Corning, Gorilla glass, thickness: 1.1 mm, Young's modulus: 72 GPa) was used as the first hard body and the second hard body. Moreover, in Example 11, a stainless steel plate (SUS304, BA polished surface, thickness: 1.0 mm, Young's modulus: 200 GPa) was used as the first hard body and the second hard body.

[Test Example 1] (Measurement of adhesive force)

The pressure-sensitive adhesive layer formed on the release sheet in each production example was bonded to one side of a PET film (manufactured by Toyobo, PET A4300, thickness: 100 µm) to obtain a laminate of release sheet/adhesive layer/PET film. However, in Production Examples 1 and 2, since the same configuration was already obtained, it was used as a laminate as it is. The obtained laminate was cut into 25 mm in width and 100 mm in length, and this was used as a sample.

In an environment of 23°C and 50% RH, the release sheet was peeled from the sample, and the exposed pressure-sensitive adhesive layer was 2 kg of a glass plate made of float glass (soda lime glass, thickness: 1.1 mm). It affixed using a rubber roller, and it left for 20 minutes.

Thereafter, using a universal tensile tester (manufactured by Orientec, Tensilon UTM-4-100), according to JIS Z0237:2009, adhesion (N/min) under conditions of a peel rate of 300 mm/min and a peel angle of 180° 25 mm) was measured. Table 1 shows the results.

Further, based on the above results, the ratio (F1/F2) of the adhesive force (F1) of the first adhesive layer to the adhesive force (F2) of the second adhesive layer used in the Examples and Comparative Examples was calculated. The results are shown in Table 2.

[Test Example 2] (Measurement of 100% modulus)

For the first pressure-sensitive adhesive layer used in Examples and Comparative Examples (silicone pressure-sensitive adhesive layers A, B and acrylic pressure-sensitive adhesive layers B, D formed on the release sheet in the above Preparation Example), a universal tensile tester (manufactured by Orientec, Tensilon UTM-4-100), measure the stress-elongation curve at a width of a sample piece of 5 mm, a tensile interval of 20 mm, and a tensile speed of 300 mm/min, and convert the stress value at which the elongation becomes 100% in MPa to 100 It was set as% modulus. The results are shown in Table 2.

[Test Example 3] (Evaluation of rework property)

The double-sided pressure-sensitive adhesive sheet protruding from the laminate produced in Examples and Comparative Examples was set in a universal tensile tester (manufactured by Orientech, Tensilon UTM-4-100), and according to JIS Z0237:2009, a peel rate of 300 The peeling force (N/25 mm) of the first pressure-sensitive adhesive layer in the double-sided pressure-sensitive adhesive sheet with respect to the first hard body was measured under the conditions of mm/min and a peel angle of 90° (peeling upward). The results are shown in Table 2.

Moreover, after performing the said peeling test, the presence or absence of adhesive residue on the surface of the 1st hard body was visually confirmed, and the adhesive residue was evaluated based on the following criteria. The results are shown in Table 2.

◎… There was no residual adhesive.

○… There was an adhesive residual of less than 20% of the bonding area.

△... There was an adhesive residual of 20% or more and less than 50% of the bonding area.

×… There was 50% or more of the adhesive residual of the bonding area.

In addition, when the peeling force is 50N/25mm or less, preferably 30N/25mm or less, and there is no residual adhesive, it can be said to be excellent in rework property.

As can be seen from Table 2, the double-sided pressure-sensitive adhesive sheet obtained in Examples was excellent in rework property in the case of peeling off the hard body.

Industrial availability

The double-sided pressure-sensitive adhesive sheet of the present invention can be suitably used for bonding a member including a display module or a display module and a cover material or a member including a cover material in, for example, a capacitive touch panel. .

1: double-sided adhesive sheet
11: first adhesive layer
11S: 1st adhesive surface
12: second adhesive layer
12S: 2nd adhesive surface
13: heartwood
2a, 2b: release sheet
3: Double-sided adhesive sheet with a release sheet attached
4: first hard body
5: second hard body
10: laminate

Claims (15)

As a laminate formed by bonding a first hard body and a second hard body through a double-sided adhesive sheet,
The first hard body is a display body module,
The double-sided pressure-sensitive adhesive sheet includes a first adhesive surface adhered to the first hard body or a member laminated on the first hard body side, and a second adhesive surface bonded to the second hard body or a member laminated on the second hard body side It has an adhesive surface,
The double-sided adhesive sheet includes a first adhesive layer having the first adhesive surface and a second adhesive layer having the second adhesive surface,
The adhesive force of the first adhesive surface to the first hard body or the member laminated on the first hard body side is F1, the second hard body or the second adhesive surface to the member laminated on the second hard body side When the adhesive force is F2, the ratio of F1 to F2 (F1/F2) is 0.0001 to 0.022,
The adhesive force of the first adhesive layer to the float glass according to JIS Z0237:2009 on the first adhesive surface is 1 N/25 mm or less,
100% modulus of the first pressure-sensitive adhesive layer is 0.3 to 1.5 MPa
A laminate, characterized in that. delete The laminate according to claim 1, wherein a ratio of the thickness of the first pressure-sensitive adhesive layer to the thickness of the second pressure-sensitive adhesive layer is 0.01 to 10. The laminate according to claim 1, wherein a core material is provided between the first adhesive layer and the second adhesive layer. The laminate according to claim 1, wherein the first pressure-sensitive adhesive layer is made of a silicone pressure-sensitive adhesive containing organopolysiloxane. The laminate according to claim 5, wherein the silicone pressure-sensitive adhesive contains an addition-type organopolysiloxane and an organopolysiloxane containing a trifunctional or tetrafunctional siloxane unit. The laminate according to claim 6, wherein the addition-type organopolysiloxane is obtained by reacting an organopolysiloxane having an alkenyl group and an organohydrogenpolysiloxane having a siloxane bond as a main skeleton. The laminate according to claim 1, wherein the adhesive force of the first adhesive layer on the first adhesive surface to the float glass according to JIS Z0237:2009 is 0.01 N/25 mm or more. delete The laminate according to claim 1, wherein the second pressure-sensitive adhesive layer is made of an acrylic pressure-sensitive adhesive containing a (meth)acrylic acid ester polymer or an ultraviolet-curable pressure-sensitive adhesive. The laminate according to claim 4, wherein the core material is made of a polyester film. delete The laminate according to claim 1, wherein the second hard body is a cover material. The laminate according to claim 1, wherein the first hard body and the second hard body are members constituting a touch panel. As a laminate formed by bonding a first hard body and a second hard body through a double-sided adhesive sheet,
The first hard body is a display body module,
The double-sided pressure-sensitive adhesive sheet includes a first adhesive surface adhered to the first hard body or a member laminated on the first hard body side, and a second adhesive surface bonded to the second hard body or a member laminated on the second hard body side It has an adhesive surface,
The double-sided adhesive sheet includes a first adhesive layer having the first adhesive surface, a second adhesive layer having the second adhesive surface, and a core material provided between the first adhesive layer and the second adhesive layer, There,
The adhesive force of the first adhesive surface to the first hard body or the member laminated on the first hard body side is F1, the second hard body or the second adhesive surface to the member laminated on the second hard body side When the adhesive force is F2, the ratio of F1 to F2 (F1/F2) is 0.0001 to 0.1,
The adhesive force of the first adhesive layer to the float glass according to JIS Z0237:2009 on the first adhesive surface is 1 N/25 mm or less,
The laminate, wherein the first pressure-sensitive adhesive layer has a 100% modulus of 0.3 to 1.5 MPa.

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