Adhesive, adhesive sheet, laminated member, and display device

Abstract

The present invention provides an adhesive agent capable of dispersing an impact even when the impact applied locally is strong. The adhesive is continuously pressed on the surface of the adhesive having a thickness of 800 [mu] m at a pressing speed of 0.01 mm / sec and the pressing depth when the pressing load reaches 10 N is 140 [mu] m or less, and the equivalent circle radius of the color development area of a pressure measurement film obtained by a pressure dispersibility test is 3 cm or more. A pressure dispersion test is performed by placing a laminate of a PET substrate having a thickness of 38 [mu] m, an adhesive, and soda-lime glass having a thickness of 700 [mu] m on an LLLW for prescale ultra-low pressure in such a manner that the surface on the soda-lime glass side in the laminate is brought into contact with the LLLW for prescale ultra-low pressure, and pressing the laminate on the LLLW for prescale ultra-low pressure. And a test in which 100 g of the ballpoint pen is dropped onto the substrate-side surface of the laminate from a height of 30 cm from the substrate-side surface, and the tip of the ballpoint pen having a tip diameter of 0.5 mm is brought into contact with the substrate-side surface.

Description

Technical Field

[0001] The present invention relates to an adhesive, an adhesive sheet, a laminated member, and a display body. Background Art

[0002] A display device formed by laminating display members such as liquid crystal elements, light-emitting diode (LED) elements, and organic electroluminescence (organic EL) elements with other members (for example, a protective panel for protecting the display member) constitutes a display body (display) of an electronic device or the like.

[0003] In addition, in various portable electronic devices such as smartphones and tablet terminals in recent years, as a display body, a touch panel in which the above display device is combined with a position input member is used.

[0004] The touch panel is a laminate including a display member and a position input detection member. In the touch panel, these members are laminated by bonding with an adhesive layer of an adhesive sheet.

[0005] For portable electronic devices, in order to achieve miniaturization and weight reduction, the display body is being thinned and flexibilized. However, for reasons such as excellent optical properties, high hardness, and high transparency, glass members are used for display members. Therefore, in order to promote the thinning and flexibilization of the display body, it is necessary to thin the glass member, but if the glass member is thinned, there is a problem that it is easily broken by an external impact.

[0006] Patent Document 1 discloses an optical film set that can improve the fracture tolerance of a glass film provided on the observation side of an optical element.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: International Publication No. 2020 / 203128 Summary of the Invention

[0010] (I) Technical Problems to be Solved

[0011] However, in Patent Document 1, the glass film is provided on the surface of the observation side of the optical element, and there is a problem that the glass film may be damaged when a strong local force is applied to the glass film.

[0012] In particular, the glass member used in the display body of a portable electronic device is easily subjected to impacts such as an object falling on the screen during the use of the electronic device. In addition, not only relatively light objects such as writing utensils and styli, but also relatively heavy objects are likely to fall on the screen.

[0013] The present invention has been completed in view of the above actual situation, and its object is to provide an adhesive that can disperse the impact even when the impact applied locally is strong.

[0014] (II) Technical solution

[0015] The solution of the present invention is as follows.

[0016] [1] An adhesive, wherein when continuously pressing the surface of the adhesive with a thickness of 800 μm at a pressing speed of 0.01 mm / second and the pressing load reaches 10 N, the pressing depth is 140 μm or less.

[0017] Through the pressure dispersion test shown below, the equivalent circle radius of the colored area of the pressure measurement film is 3 cm or more.

[0018] (Pressure dispersion test)

[0019] Prepare a laminate formed by sequentially laminating a substrate made of polyethylene terephthalate with a thickness of 38 μm, an adhesive, and a soda-lime glass with a thickness of 700 μm. Place the laminate on "Prescale extra low pressure LLLW" manufactured by Fuji Film Co., Ltd. in such a way that the surface on the soda-lime glass side of the laminate contacts the pressure measurement film. Drop a ballpoint pen weighing 100 g from a height of 30 cm from the surface on the substrate side of the laminate onto the surface on the substrate side of the laminate, and make the tip of the ballpoint pen with a tip diameter of 0.5 mm contact the surface on the substrate side of the laminate, thereby applying pressure to the laminate.

[0020] [2] The adhesive according to [1], wherein the adhesive strength is 1 N / 25 mm or more and 100 N / 25 mm or less.

[0021] [3] The adhesive according to [1] or [2], wherein the gel fraction of the adhesive is 30% or more and 99% or less.

[0022] [4] The adhesive according to any one of [1] to [3], wherein the adhesive is an acrylic adhesive.

[0023] [5] An adhesive sheet having an adhesive layer, wherein the adhesive layer is composed of the adhesive according to any one of [1] to [4].

[0024] [6] The adhesive sheet according to [5], further having a release sheet, and the release sheet is provided on the main surface of the adhesive layer.

[0025] [7] A laminated member includes a first member made of glass, a second member, and an adhesive layer that bonds the first member and the second member to each other, wherein the adhesive layer is made of the adhesive according to any one of [1] to [4].

[0026] [8] The laminated member according to [7], wherein the thickness of the first member is 40 μm or more and 2000 μm or less.

[0027] [9] A display body includes the laminated member according to [7] or [8].

[0028] (III) Advantageous Effects

[0029] According to the present invention, an adhesive that can disperse an impact even when the impact locally applied is strong can be provided. Description of the Drawings

[0030] Figure 1 It is a schematic diagram for explaining the pressing depth.

[0031] Figure 2 It is a cross-sectional schematic diagram of an adhesive sheet according to an embodiment of the present invention.

[0032] Figure 3 It is a cross-sectional view of a laminated member according to an embodiment of the present invention.

[0033] Figure 4 It is a schematic diagram for explaining the pen dropping test in the examples. Detailed Description of the Invention

[0034] Hereinafter, the present invention will be described in detail based on specific embodiments.

[0035] (1. Adhesive)

[0036] The adhesive of the present embodiment is used to bond the first member and the second member. In particular, it is preferable that the first member is a glass member.

[0037] Since the glass member has excellent optical properties and high hardness and transparency, it is preferably used as a member constituting a display. However, with the miniaturization and lightening of portable electronic devices, in order to miniaturize and lighten the display body, it is necessary to thin the glass member. As described above, if the glass member is thinned, the impact resistance of the glass member will deteriorate. In particular, when an object drops onto the screen or the like and the local impact increases, the tolerance for such an impact will deteriorate. In this way, there is a problem that the glass member is likely to be damaged due to impacts applied during the use of the electronic device.

[0038] In order to solve the above problems, the physical properties of the adhesive of this embodiment are controlled. Hereinafter, the adhesive of this embodiment will be described in detail. The adhesive of this embodiment is a pressure-sensitive adhesive.

[0039] (1.1. Physical properties of the adhesive)

[0040] The adhesive of this embodiment has the physical properties shown below.

[0041] (1.1.1. Pressing depth)

[0042] In this embodiment, the pressing depth of the surface of the adhesive is controlled. As Figure 1 shown, the pressing depth is: continuously pressing the surface of the adhesive 10 with a thickness of 800 μm at a pressing speed of 0.01 mm / second ( Figure 1 10a in) and the pressing depth h when the pressing load L reaches 10 N.

[0043] In this embodiment, the pressing depth is 140 μm or less. The pressing depth reflects the degree of resistance of the adhesive to locally applied stress. The smaller the pressing depth, the more the locally applied stress will be dispersed on the surface of the adhesive, thereby suppressing local deformation of the adhesive. In this way, the impact applied to the glass member attached to the adhesive will also be dispersed, thereby suppressing breakage of the glass member.

[0044] From the above perspective, the pressing depth is preferably 130 μm or less, more preferably 125 μm or less, and further preferably 120 μm or less. On the other hand, the lower limit of the pressing depth is not particularly limited. In this embodiment, from the perspective of improving the degree of resistance to locally applied stress, the lower limit of the pressing depth is preferably 0 μm.

[0045] The method for measuring the pressing depth will be described in detail in the following examples. In addition, as the adhesive with a thickness of 800 μm, it can be a single-layer adhesive or an adhesive formed by laminating adhesives with a specified thickness so that the total thickness is 800 μm.

[0046] (1.1.2. Storage modulus)

[0047] In this embodiment, the storage modulus (G’) of the adhesive at 23°C and a frequency of 1 Hz is preferably 0.01 MPa or more and 2 MPa or less. The storage modulus is one of the indexes of the ease of deformation (hardness) of the adhesive layer. By making the storage modulus of the adhesive at 23°C within the above range, the pressing depth can be easily within the above range.

[0048] From the above perspectives, the storage modulus of the adhesive is more preferably 0.02 to 1.5 MPa, further preferably 0.03 to 1 MPa, and particularly preferably 0.04 to 0.8 MPa. The storage modulus of the adhesive can be adjusted, for example, by changing the composition of the adhesive (the type and amount of reactive functional groups, the molecular structure of the monomer composition used, the glass transition temperature, etc.), the molecular weight of the material constituting the adhesive, etc.

[0049] The storage modulus (G') can be measured using a known method. For example, the adhesive layer is made into a sample of a specified size, and a dynamic viscoelasticity measuring device is used to apply strain to the sample at a specified frequency within a specified temperature range to measure the elastic modulus. The storage modulus under the above conditions can be calculated from the measured elastic modulus.

[0050] (1.1.3. Adhesion)

[0051] In this embodiment, the adhesive force of the adhesive to the soda-lime glass is preferably 1N / 25mm or more and 100N / 25mm or less. By making the adhesive force within the above range, it is easy to fully adhere to the adherend to which it is attached, so even if, for example, local stress is applied across the adherend, the adhesive layer can easily absorb the stress. It is estimated that there is a tendency to improve the stress dispersibility in the adhesive layer, and it is easy to make the pressing depth within the above range.

[0052] From the above viewpoints, the adhesive force is more preferably 3 to 80 N / 25 mm, further preferably 5 to 60 N / 25 mm, and particularly preferably 8 to 55 N / 25 mm.

[0053] (1.1.4. Gel fraction)

[0054] The gel fraction of the adhesive of this embodiment is preferably 30% or more and 99% or less. This makes it easy to make the pressing depth within the above range.

[0055] The gel fraction of the adhesive of this embodiment is more preferably 35 to 95%, further preferably 40 to 90%, particularly preferably 45 to 84%, and particularly preferably 50 to 78%. The gel fraction of the adhesive can be measured by the method shown in the test examples described below.

[0056] (1.2. Composition of adhesive)

[0057] As long as the adhesive has the above physical properties, the composition of the adhesive is not particularly limited. For example, it may be any one of acrylic adhesives, polyester adhesives, polyurethane adhesives, rubber adhesives, silicone adhesives, etc. In addition, the adhesive may be any one of emulsion type, solvent type or solvent-free type. Further, the adhesive may have a crosslinked structure or may not have a crosslinked structure.

[0058] In the present embodiment, from the perspective of the ease of achieving the above physical properties, as well as from the perspectives of adhesive properties, optical properties, etc., as the adhesive, an acrylic adhesive is preferred, and an acrylic adhesive having a crosslinked structure is more preferred.

[0059] Specifically, the adhesive is preferably an adhesive obtained by crosslinking an adhesive composition (hereinafter, sometimes referred to as "adhesive composition P") containing a (meth)acrylate polymer (A) and a crosslinking agent (B). If it is this adhesive, it is easy to satisfy the above physical properties and it is easy to obtain good adhesive force. In addition, in this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. In addition, the term "polymer" also includes the concept of "copolymer".

[0060] (1.2.1. (Meth)acrylate polymer)

[0061] (Meth)acrylate polymer (A) preferably contains a (meth)acrylate alkyl ester and a monomer having a reactive functional group in the molecule (reactive functional group-containing monomer) as monomer units constituting the polymer.

[0062] By containing a (meth)acrylate alkyl ester, the resulting adhesive can exhibit preferred adhesiveness. As the (meth)acrylate alkyl ester, a (meth)acrylate alkyl ester having 1 to 20 carbon atoms in the alkyl group is preferred. The alkyl group may be linear or branched, and may have a cyclic structure.

[0063] Examples of the (meth)acrylate alkyl ester having 1 to 20 carbon atoms in the alkyl group include (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, (meth)acrylic acid n-butyl ester, (meth)acrylic acid n-pentyl ester, (meth)acrylic acid n-hexyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid isooctyl ester, (meth)acrylic acid n-decyl ester, (meth)acrylic acid n-dodecyl ester, (meth)acrylic acid tetradecyl ester, (meth)acrylic acid hexadecyl ester, (meth)acrylic acid octadecyl ester, etc.

[0064] Among them, from the perspective of controlling the pressing depth, it is preferable that the alkyl group of the (meth)acrylate has 1 to 8 carbon atoms. Specifically, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are preferred, and methyl methacrylate, n-butyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate are particularly preferred. In addition, these alkyl (meth)acrylates can be used alone or in combination of two or more.

[0065] The (meth)acrylate polymer (A) preferably contains 40 to 99.9% by mass of an alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer, more preferably contains 50 to 99% by mass of an alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group, and still more preferably contains 55 to 97% by mass of an alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group. Thereby, appropriate adhesiveness can be imparted. In addition, a required amount of other monomer components can be introduced into the (meth)acrylate polymer (A) to more easily design an adhesive that exhibits the required performance.

[0066] By making the (meth)acrylate polymer (A) contain a monomer having a reactive functional group as a monomer unit constituting the polymer, the (meth)acrylate polymer (A) can react with a crosslinking agent (B) described later through the reactive functional group derived from the monomer having a reactive functional group to form a crosslinked structure (three-dimensional network structure) in the adhesive. As a result, an adhesive having the required cohesive force can be obtained.

[0067] As the monomer having a reactive functional group, monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomers), monomers having a carboxyl group in the molecule (carboxyl group-containing monomers), monomers having an amino group in the molecule (amino group-containing monomers), etc. are preferably listed. These monomers having a reactive functional group can be used alone or two or more of them can be used simultaneously.

[0068] Among them, a hydroxyl group-containing monomer or a carboxyl group-containing monomer is preferred. Thereby, the obtained adhesive can easily satisfy the above physical properties.

[0069] Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0070] Among them, from the perspective of easily realizing the physical properties related to the above-mentioned pressing depth, a (meth)acrylic acid hydroxyalkyl ester having a hydroxyalkyl group with 1 to 4 carbon atoms is preferred. Specifically, for example, 2-hydroxyethyl (meth)acrylate etc. are preferably exemplified, and in particular, 2-hydroxyethyl acrylate is preferably exemplified. These hydroxy group-containing monomers can be used alone or in combination of two or more.

[0071] As the carboxyl group-containing monomers, there can be exemplified ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, etc. Among them, from the perspective of easily realizing the physical properties related to the above-mentioned pressing depth, acrylic acid or methacrylic acid is preferred, and acrylic acid is particularly preferred. These carboxyl group-containing monomers can be used alone or in combination of two or more.

[0072] (Meth)acrylate polymer (A) preferably contains 0.1 to 40% by mass of a reactive functional group-containing monomer as a monomer unit constituting the polymer, and more preferably contains 0.5 to 35% by mass of a reactive functional group-containing monomer. When the reactive functional group-containing monomer is a hydroxy group-containing monomer, it is particularly preferably contained in an amount of 0.8 to 30% by mass, and further preferably contained in an amount of 1 to 25% by mass. In addition, when the reactive functional group-containing monomer is a carboxyl group-containing monomer, it is particularly preferably contained in an amount of 0.8 to 25% by mass, and further preferably contained in an amount of 1 to 15% by mass, and among them, it is preferably contained in an amount of 3 to 8% by mass.

[0073] By making the content ratio of the reactive functional group-containing monomer within the above range, the cohesion of the adhesive obtained by the crosslinking reaction with the crosslinking agent (B) becomes appropriate, and it is easy to satisfy the physical properties, adhesive force, etc. related to the above-mentioned pressing depth, storage modulus, gel fraction, etc.

[0074] (Meth)acrylate polymer (A) preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Since the carboxyl group is an acid component, by not containing a carboxyl group-containing monomer, even in the case where there are components in the adherend of the adhesive that may cause adverse conditions due to acid, such as transparent conductive films such as tin-doped indium oxide (ITO), metal films, metal meshes, etc., adverse conditions (corrosion, change in resistance value, etc.) caused by acid can be suppressed.

[0075] Here, the so-called "not containing a carboxyl group-containing monomer" means that it basically does not contain a carboxyl group-containing monomer. In addition to completely not containing a carboxyl group-containing monomer, it is allowed to contain a carboxyl group-containing monomer in an amount that does not cause corrosion of a transparent conductive film or metal wiring, etc. Specifically, in (meth)acrylate polymer (A), as a monomer unit, it is allowed to contain 0.1% by mass or less, preferably allowed to contain 0.01% by mass or less, and further preferably allowed to contain 0.001% by mass or less of a carboxyl group-containing monomer.

[0076] (Meth)acrylate polymers preferably contain monomers having an alicyclic structure in the molecule (alicyclic structure-containing monomers) as monomer units constituting the polymers. Since the alicyclic structure-containing monomers are large in volume, it is presumed that the presence of the monomers in the polymers broadens the intervals between the polymers, enabling the resulting adhesives to have excellent flexibility. Thus, there is a tendency to easily satisfy the physical properties related to the above-mentioned storage modulus and adhesive force. In addition, since appropriate stress relaxation properties are easily exhibited, there is a tendency to easily satisfy the physical properties related to the above-mentioned pressing depth.

[0077] The carbocyclic ring of the alicyclic structure in the alicyclic structure-containing monomers may be a saturated structure or may have partial unsaturated bonds. In addition, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic or tricyclic structure (polycyclic structure). From the perspective of maintaining an appropriate distance between the resulting (meth)acrylate polymers and imparting higher stress relaxation properties to the adhesives, the above alicyclic structure is preferably a polycyclic structure. Further, considering the compatibility of the (meth)acrylate polymer (A) with other components, the above polycyclic structure is particularly preferably a bicyclic to tetracyclic structure. In addition, from the perspective of imparting stress relaxation properties and compatibility as described above, the number of carbon atoms in the alicyclic structure (refers to all carbon atoms forming the ring part, and when there are multiple rings existing independently, it refers to the total number of carbon atoms thereof) is preferably 5 to 15, more preferably 7 to 10.

[0078] Specific examples of the alicyclic structure-containing monomers include cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, and the like.

[0079] Among them, from the perspective of easily satisfying the physical properties related to the above-mentioned pressing depth, storage modulus, gel fraction, etc. and easily satisfying the adhesive force, dicyclopentenyl (meth)acrylate (number of carbon atoms in the alicyclic structure: 10), adamantyl (meth)acrylate (number of carbon atoms in the alicyclic structure: 10), or isobornyl (meth)acrylate (number of carbon atoms in the alicyclic structure: 7) is preferred, isobornyl (meth)acrylate is particularly preferred, and isobornyl acrylate is further preferred. These alicyclic structure-containing monomers can be used alone or in combination of two or more.

[0080] When a monomer unit containing an alicyclic structure monomer is included as a monomer unit constituting the polymer, the (meth)acrylate polymer preferably contains 1 to 20% by mass of the alicyclic structure monomer, more preferably contains 4 to 16% by mass of the alicyclic structure monomer, and still more preferably contains 7 to 12% by mass of the alicyclic structure monomer. Thereby, it is easy to satisfy the physical properties and adhesiveness related to the above-mentioned pressing depth, storage modulus, gel fraction, etc.

[0081] The above (meth)acrylate polymer also preferably contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. Thereby, a predetermined polarity can be imparted to the adhesive, and the adhesiveness is also excellent for an adherend having a certain degree of polarity. As the nitrogen atom-containing monomer, from the viewpoint of imparting moderate rigidity to the (meth)acrylate polymer (A), a monomer having a nitrogen-containing heterocycle is preferred. In addition, from the viewpoint of increasing the degree of freedom of the portion derived from the nitrogen atom-containing monomer in the higher-order structure of the formed adhesive, it is preferred that the nitrogen atom-containing monomer does not contain a reactive unsaturated double bond group except for one polymerizable group used in the polymerization for forming the (meth)acrylate polymer.

[0082] Examples of the monomer having a nitrogen-containing heterocycle include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrole, N-(meth)acryloylaziridine, aziridinylethyl (meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, and the like.

[0083] Among them, N-(meth)acryloylmorpholine, which exhibits more excellent adhesiveness, is preferred, and N-acryloylmorpholine is particularly preferred. These monomers having a nitrogen-containing heterocycle can be used alone or in combination of two or more.

[0084] When a nitrogen atom-containing monomer is included as a monomer unit constituting the polymer, the (meth)acrylate polymer preferably contains 1 to 20% by mass of the nitrogen atom-containing monomer, more preferably contains 4 to 16% by mass of the nitrogen atom-containing monomer, and still more preferably contains 7 to 12% by mass of the nitrogen atom-containing monomer. Thereby, it is easy to satisfy the physical properties and adhesiveness related to the above-mentioned pressing depth, storage modulus, gel fraction, etc.

[0085] (Meth)acrylate polymer (A) also preferably contains an aromatic ring-containing monomer as a monomer unit constituting the polymer. Thereby, it is easy to satisfy the physical properties and adhesiveness related to the above-mentioned pressing depth, storage modulus, gel fraction, etc.

[0086] As the aromatic ring-containing monomer, for example, phenyl (meth)acrylate, 2-phenylethyl (meth)acrylate, benzyl (meth)acrylate, naphthyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxybutyl (meth)acrylate, ethoxylated o-phenylphenol acrylate, phenoxydiethylene glycol (meth)acrylate, ethylene oxide-modified cresol (meth)acrylate, ethylene oxide (EO)-modified nonylphenol (meth)acrylate, etc. can be cited. Among them, 2-phenylethyl (meth)acrylate is preferred in terms of polymerizability. These aromatic ring-containing monomers can be used alone or in combination of two or more.

[0087] (Meth)acrylate polymer (A) preferably contains 0.1 to 10% by mass of the aromatic ring-containing monomer as a monomer unit constituting the polymer, preferably contains 1 to 8% by mass of the aromatic ring-containing monomer, and particularly preferably contains 2 to 5% by mass of the aromatic ring-containing monomer. Thereby, the obtained adhesive exhibits excellent stress relaxation properties and cohesion, and easily satisfies the physical properties and adhesiveness related to the above-mentioned pressing depth, storage modulus, gel fraction, etc.

[0088] In this embodiment, the (meth)acrylate polymer may optionally contain other monomers as monomer units constituting the polymer. As the other monomers, in order not to hinder the above-mentioned action of the monomer containing a reactive functional group, monomers not containing a reactive functional group are preferred. As such monomers, (meth)acrylate alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, styrene, etc. can be exemplified. These other monomers can be used alone or in combination of two or more.

[0089] (Meth)acrylate polymer (A) can be a random copolymer or a block copolymer in terms of polymerization form.

[0090] (Meth)acrylate polymer (A) preferably has a weight average molecular weight of 100,000 to 3,000,000, more preferably 200,000 to 2,000,000, further preferably 300,000 to 1,200,000, and particularly preferably 400,000 to 1,000,000, and among them, preferably 500,000 to 800,000. Thereby, the obtained adhesive easily satisfies the physical properties and adhesiveness related to the above-mentioned pressing depth, storage modulus, gel fraction, etc. In addition, the weight average molecular weight in this specification is a value in terms of standard polystyrene measured by gel permeation chromatography (GPC).

[0091] In the adhesive composition P, one kind of (meth)acrylate polymer (A) can be used alone or two or more kinds can be used in combination.

[0092] (1.2.2. Crosslinking agent)

[0093] The crosslinking agent (B) crosslinks the (meth)acrylate polymer (A) upon heating or the like of the pressure-sensitive adhesive composition P containing the crosslinking agent (B), forming a crosslinked structure (three-dimensional network structure). As a result, the cohesion of the resulting pressure-sensitive adhesive increases, and it is easy to satisfy the physical properties and adhesive strength related to the above-mentioned storage modulus G'.

[0094] As the crosslinking agent (B), any compound that can react with the reactive functional groups possessed by the (meth)acrylate polymer (A) may be used. For example, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, etc., melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, ammonium salt-based crosslinking agents, etc. can be exemplified. Among them, from the perspective of excellent reactivity with monomers containing reactive functional groups and the resulting pressure-sensitive adhesive being easily able to satisfy the required pressing depth, it is preferable to use an isocyanate-based crosslinking agent or a metal chelate-based crosslinking agent. In addition, the crosslinking agent (B) can be used alone or in combination of two or more.

[0095] The isocyanate-based crosslinking agent at least contains a polyisocyanate compound. As the polyisocyanate compound, for example, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, and alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and their biuret bodies, isocyanurate bodies, and adducts as reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil can be cited.

[0096] As the metal chelate-based crosslinking agent, there are chelate compounds in which the metal atom is aluminum, zirconium, titanium, zinc, iron, tin, etc. In terms of performance, aluminum chelates are preferred. As the aluminum chelate, for example, diisopropoxyaluminum monooleate acetylacetonate, monoisopropoxyaluminum dioleate acetylacetonate, monoisopropoxyaluminum monooleate monoethyl acetylacetonate, diisopropoxyaluminum monolaurate acetylacetonate, diisopropoxyaluminum monostearate acetylacetonate, diisopropoxyaluminum monoisostearate acetylacetonate, monoisopropoxyaluminum mono-N-lauroyl-β-alanine monolaurate acetylacetonate, aluminum acetylacetonate, monacetylacetonate aluminum bis(isobutyl acetylacetonate) chelate, monacetylacetonate aluminum bis(2-ethylhexyl acetylacetonate) chelate, monacetylacetonate aluminum bis(dodecyl acetylacetonate) chelate, monacetylacetonate aluminum bis(oleate acetylacetonate) chelate, etc. can be cited.

[0097] The content of the crosslinking agent (B) in the pressure-sensitive adhesive composition P is preferably 0.01 to 2 parts by mass, more preferably 0.05 to 1 part by mass, still more preferably 0.1 to 0.8 part by mass, and particularly preferably 0.15 to 0.7 part by mass, relative to 100 parts by mass of the (meth)acrylate polymer (A). Thus, it is easy to satisfy the physical properties and adhesive force related to the above-mentioned pressing depth, storage modulus, gel fraction, etc.

[0098] (1.2.3. Actinic energy ray curable component)

[0099] When the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition P of the present embodiment is an actinic energy ray curable pressure-sensitive adhesive, the pressure-sensitive adhesive composition P preferably contains an actinic energy ray curable component. Thus, the pressure-sensitive adhesive obtained by crosslinking (thermal crosslinking) the pressure-sensitive adhesive composition P becomes an actinic energy ray curable pressure-sensitive adhesive. It is presumed that in this actinic energy ray curable pressure-sensitive adhesive, due to the curing caused by the irradiation of actinic energy rays after being attached to the adherend, the actinic energy ray curable components polymerize with each other, and the polymerized actinic energy ray curable components wind around the crosslinked structure (three-dimensional network structure) of the (meth)acrylate polymer (A). The cohesive force of the pressure-sensitive adhesive having this higher-order structure is high and shows a higher film laminating strength, so it is easy to satisfy the above-mentioned pressing depth and has excellent pen drop resistance.

[0100] The actinic energy ray curable component is not particularly limited as long as it is cured by the irradiation of actinic energy rays and can obtain the above effects, and it can be any one of monomers, oligomers or polymers, or a mixture thereof. Among them, from the viewpoint of easily satisfying the physical properties and adhesive force related to the above-mentioned pressing depth, storage modulus, gel fraction, etc., an actinic energy ray curable monomer or oligomer is preferred, and polyfunctional acrylate monomers can be preferably cited. From the viewpoint of compatibility with the (meth)acrylate polymer (A), the polyfunctional acrylate monomer preferably has a molecular weight of less than 1000.

[0101] When the pressure-sensitive adhesive composition P contains an actinic energy ray curable component, the content of the actinic energy ray curable component is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and particularly preferably 3 to 10 parts by mass, relative to 100 parts by mass of the (meth)acrylate polymer (A). Thus, it is easy to satisfy the physical properties and adhesive force related to the above-mentioned pressing depth, storage modulus, gel fraction, etc.

[0102] (1.2.4. Photoinitiator)

[0103] When the adhesive obtained from the pressure-sensitive adhesive composition P of the present embodiment is an active energy ray-curable pressure-sensitive adhesive, when ultraviolet rays are used as the active energy rays, the pressure-sensitive adhesive composition P preferably further contains a photoinitiator. Thereby, the active energy ray-curable components can be polymerized efficiently, and the polymerization curing time and the irradiation amount of the active energy rays can be reduced. As the photoinitiator, known photoinitiators can be used, one photoinitiator can be used, or two or more can be used in combination.

[0104] When the pressure-sensitive adhesive composition P contains an active energy ray-curable component and a photoinitiator, the content of the photoinitiator is preferably 0.1 to 30 parts by mass, particularly preferably 1 to 20 parts by mass, and further preferably 5 to 15 parts by mass with respect to 100 parts by mass of the active energy ray-curable component. Thereby, the adhesive strength of the pressure-sensitive adhesive after curing with active energy rays can be increased, and it is easy to satisfy the physical properties and adhesive strength related to the above-mentioned pressing depth, storage modulus, gel fraction, etc.

[0105] (1.2.5. Other additives)

[0106] The pressure-sensitive adhesive composition P may further contain additives commonly used in acrylic pressure-sensitive adhesives as needed. Examples of such additives include silane coupling agents, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, rust inhibitors, fillers, refractive index modifiers, etc. In addition, the additives constituting the pressure-sensitive adhesive composition P do not include the polymerization solvents, diluting solvents, etc. described later.

[0107] Among them, the pressure-sensitive adhesive composition P preferably contains a silane coupling agent. Thereby, the adhesion to the adherend is increased, and along with this, it is easy to satisfy the above-mentioned pressing depth and the pen-drop resistance is excellent.

[0108] As the silane coupling agent, an organosilicon compound having at least one alkoxysilyl group in the molecule, good compatibility with the (meth)acrylate polymer (A), and having light transmittance is preferred. Examples of such silane coupling agents include silicon compounds containing polymerizable unsaturated groups, silicon compounds having an epoxy structure, silicon compounds containing a mercapto group, silicon compounds containing an amino group, condensates of silicon compounds containing an alkyl group, etc. These silane coupling agents can be used alone or in combination of two or more.

[0109] The content of the silane coupling agent in the pressure-sensitive adhesive composition P is preferably 0.01 to 1 part by mass, particularly preferably 0.05 to 0.7 part by mass or more, and further preferably 0.1 to 0.4 part by mass with respect to 100 parts by mass of the (meth)acrylate polymer (A). Thereby, the adhesion to the adherend is increased, and along with this, it is easy to satisfy the above-mentioned pressing depth and the pen-drop resistance is excellent.

[0110] (1.3. Preparation of the Adhesive Composition)

[0111] The adhesive composition P can be prepared, for example, in the following manner: First, a (meth)acrylate polymer (A) is produced, and the resulting (meth)acrylate polymer (A) is mixed with a crosslinking agent (B). Additives can also be added as needed.

[0112] The (meth)acrylate polymer (A) can be produced, for example, by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. The polymerization of the (meth)acrylate polymer (A) can be carried out using a polymerization initiator as needed and by solution polymerization. By polymerizing the (meth)acrylate polymer (A) by solution polymerization, the high molecular weight of the resulting polymer and the adjustment of the molecular weight distribution become easy, and the generation of low molecular weight substances can be further reduced. As a result, it is easy to obtain an adhesive that easily satisfies the physical properties and adhesive force related to the above-mentioned pressing depth, storage modulus, gel fraction, etc.

[0113] Examples of the polymerization solvent used in the solution polymerization method include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc. Only one polymerization solvent can be used, or two or more can be used simultaneously. Examples of the polymerization initiator include azo compounds, organic peroxides, etc., and two or more can be used simultaneously. In addition, in the above polymerization process, the weight average molecular weight of the resulting polymer can be adjusted by blending a chain transfer agent such as 2-mercaptoethanol.

[0114] Subsequently, a crosslinking agent (B) and a diluting solvent are added to the solution of the obtained (meth)acrylate polymer (A) and mixed well, thereby obtaining a solvent-diluted adhesive composition P (coating liquid). Additives can also be added as needed.

[0115] In addition, for any of the above components, in the case of a solid component or in the case of precipitation when mixed with other components in an undiluted state, the component can be pre-dissolved or diluted in a diluting solvent and then mixed with other components.

[0116] Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane, cyclohexane; aromatic hydrocarbons such as toluene, xylene; halogenated hydrocarbons such as dichloromethane, vinyl chloride; alcohols such as methanol, ethanol, propanol, butanol, 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone; esters such as ethyl acetate, butyl acetate; cellosolve solvents such as ethyl cellosolve, etc.

[0117] As for the concentration and viscosity of the prepared coating solution, it is sufficient as long as it is within the range that can be coated, and it can be appropriately selected according to the situation. For example, it is diluted so that the concentration of the adhesive composition P becomes 10 to 60% by mass. In addition, when obtaining the coating solution, the addition of a diluting solvent or the like is not a necessary condition. If the viscosity of the adhesive composition P enables coating, the diluting solvent may not be added. In this case, the adhesive composition P is a coating solution that directly uses the polymerization solvent of the (meth)acrylate polymer (A) as the diluting solvent.

[0118] (1.4. Manufacture of Adhesive)

[0119] The adhesive constituting the adhesive layer is preferably obtained by crosslinking the above-mentioned adhesive composition P. The crosslinking of the adhesive composition P can generally be carried out by heat treatment. In addition, this heat treatment can also serve as a drying treatment for volatilizing the diluting solvent or the like from the coating film of the adhesive composition P coated on the desired object.

[0120] The heating temperature of the heat treatment is preferably 50 to 150 °C, more preferably 70 to 120 °C. In addition, the heating time is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes.

[0121] After the heat treatment, a curing period of about 1 to 2 weeks can be set at room temperature (for example, 23 °C, 50% RH) as needed. When this curing period is required, an adhesive having a crosslinked structure is obtained after the curing period. When the curing period is not required, an adhesive having a crosslinked structure is obtained after the heat treatment is completed.

[0122] (2. Adhesive Sheet)

[0123] The adhesive sheet of the present embodiment has at least an adhesive layer. The adhesive layer is composed of the above-mentioned adhesive. In addition, as long as the effects of the present invention can be obtained, the adhesive sheet may also have constituent elements other than the adhesive layer. In the present embodiment, for example, as shown in Figure 2 , for the purpose of protecting the adhesive layer 10 before using the adhesive sheet 1, two release sheets 11 and 12 are provided on the surface of the adhesive layer 10 so as to sandwich the adhesive layer 10.

[0124] (2.1. Adhesive Layer)

[0125] The adhesive layer bonds the first member and the second member. In the present embodiment, the adhesive layer preferably bonds the first member made of glass and the second member. By making the adhesive constituting the adhesive layer have the above physical properties, the first member and the second member can be sufficiently bonded. Further, by bonding the member made of glass and other members using this adhesive layer, excellent pen-drop resistance of the laminated member can be obtained.

[0126] The adhesive layer may be formed of a single layer or multiple layers of two or more layers. When the adhesive layer has multiple layers, these multiple layers may be the same as or different from each other, and there is no particular limitation on the combination of the layers constituting these multiple layers.

[0127] The thickness of the adhesive layer 10 is preferably 1 μm or more and 1000 μm or less, more preferably 4 μm or more and 500 μm or less, further preferably 8 μm or more and 200 μm or less, and particularly preferably 12 μm or more and 100 μm or less. Among them, 16 μm or more and 50 μm or less is preferred, and 20 μm or more and 35 μm or less is most preferred. Thus, it is easy to adjust the above-mentioned pressing amount and adhesive force to the required values.

[0128] (2.2. Release sheet)

[0129] The release sheets 11 and 12 are peeled off when the adhesive sheet 1 is used. In the adhesive sheet 1 of the present embodiment, one or both of the release sheets 11 and 12 are not essential.

[0130] As the release sheet, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polyethylene naphthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene vinyl acetate film, an ionomer resin film, an ethylene-(meth)acrylic acid copolymer film, an ethylene-(meth)acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, a fluororesin film, etc. can be used. In addition, a crosslinked film of these films can also be used. In addition, a laminated film of these films can also be used.

[0131] Preferably, the release surface of the release sheet (especially the surface in contact with the adhesive layer) is subjected to a release treatment. As the release agent used for the release treatment, for example, alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, wax-based release agents, etc. can be cited. In addition, among the release sheets, it is preferred to set one of the release sheets as a heavy release type release sheet with a large release force and the other release sheet as a light release type release sheet with a small release force.

[0132] The thickness of the release sheet is not particularly limited, but is usually about 20 to 150 μm.

[0133] (2.3. Manufacture of adhesive sheet)

[0134] The manufacturing method of the adhesive sheet 1 is not particularly limited and can be manufactured by known methods. For example, a coating liquid containing the above-mentioned adhesive composition P is coated on the release surface of a first release sheet 11 (or a second release sheet 12), and heat treatment is performed to crosslink the adhesive composition P, thereby forming a coating layer with a specified thickness. The release surface of another second release sheet 12 (or the first release sheet 11) is overlapped on the formed coating layer. When a curing period is required, after the specified curing period has elapsed, the coating layer becomes the adhesive layer 10. In addition, when no curing period is required, the above-mentioned coating layer directly becomes the adhesive layer 10. Thus, the adhesive sheet 1 can be obtained.

[0135] As another manufacturing method of the adhesive sheet 1, a coating liquid containing the above-mentioned adhesive composition P is coated on the release surface of a first release sheet 11 (or a second release sheet 12), and heat treatment is performed to crosslink the adhesive composition P to form a coating layer, thereby obtaining a first release sheet 11 with a coating layer. In addition, a coating liquid containing the above-mentioned adhesive composition P is coated on the release surface of another second release sheet 12, and heat treatment is performed to crosslink the adhesive composition P to form a coating layer, thereby obtaining a second release sheet 12 with a coating layer. Then, the first release sheet 11 with a coating layer and the second release sheet 12 with a coating layer are bonded together in such a way that the two coating layers are in contact with each other. When a curing period is required, after the specified curing period has elapsed, the coating layer becomes the adhesive layer 10. In addition, when no curing period is required, the above-mentioned coating layer directly becomes the adhesive layer 10. Thus, the adhesive sheet 1 can be obtained. According to this manufacturing method, even when the adhesive layer 10 is thick, it can be stably manufactured.

[0136] As methods for coating the coating liquid of the adhesive composition P, methods such as bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating can be exemplified.

[0137] (3. Laminated member)

[0138] As Figure 3 shown, the laminated member 2 of the present embodiment includes a first member 21, a second member 22, and an adhesive layer 10 that bonds the first member 21 and the second member 22 to each other. The first member 21 is made of glass. That is, the adhesive layer 10 is used to bond a glass member and other members. The adhesive layer 10 in the laminated member 2 is the adhesive layer 10 of the above-mentioned adhesive sheet 1.

[0139] The laminated member can be, for example, a display body including a display device such as a liquid crystal display, an LED display, an electronic paper, an organic EL display, etc., or a member that forms a part of the display body. In the laminated member 2 for the display body, it is preferable that the first member is located on the display device side and the second member is located on the outside side of the display body. That is, it is preferable that the second member is a member such as a cover film or a hard coat film provided on the light-emitting side (observation side) where the display image is formed.

[0140] By configuring the laminated member in this way, even if a local force is applied to the second member side, due to the adhesive layer having the above characteristics, it is possible to prevent the first member from being damaged such as cracks and fissures due to impact.

[0141] The thickness of the first member is preferably 40 μm or more and 2000 μm or less, more preferably 200 μm or more and 1500 μm or less, further preferably 300 μm or more and 1000 μm or less, and particularly preferably 400 μm or more and 800 μm or less.

[0142] Even if the first member made of glass is a member thinned within the above range, it is possible to effectively suppress the breakage of the first member.

[0143] The thickness of the second member is preferably 10 μm or more and 2000 μm or less, more preferably 20 μm or more and 1000 μm or less, further preferably 30 μm or more and 400 μm or less, and particularly preferably 35 μm or more and 100 μm or less.

[0144] Even if the second member is a member thinned within the above range, it is possible to effectively suppress the breakage of the second member.

[0145] The tensile strength of the second member is preferably 50 to 6000 MPa, more preferably 100 to 3000 MPa, particularly preferably 150 to 1200 MPa, and further preferably 200 to 600 MPa. Thus, even when the impact applied locally is strong, it is possible to easily mitigate the impact by the second member.

[0146] In addition, each member of the laminated member 2 can also be composed of a member that can be bent, that is, a so-called flexible member. When the first member is flexible, since the thickness of the first member needs to be set within the above range, even if the laminated member is flexible, it is possible to effectively prevent the breakage of the first member.

[0147] The laminated member 2 of the present embodiment is placed on the pressure measurement film that changes color when pressure is applied, with the surface on the first member side of the laminated member 2 in contact with the pressure measurement film. Regarding the degree of color development of the pressure measurement film after a ballpoint pen is dropped on the surface on the second member side, the equivalent circle radius of the colored area in the pressure measurement film is preferably 3 cm or more, and particularly preferably 3 cm or more and less than 10 cm. Thus, even when local stress is applied, the adhesive layer can disperse the stress and prevent breakage of the laminated member, especially breakage of the first member. Moreover, even if the laminated member has flexibility, breakage of the first member can be effectively suppressed.

[0148] (4. Device)

[0149] The device of the present embodiment includes the above-mentioned laminated member, and is preferably a display body. That is, the device can be composed only of the laminated member, or can include the laminated member and other members. As the display body, as described above, it can be a display device including a liquid crystal display, an LED display, an electronic paper, an organic EL display, etc. In addition, it can also be a touch panel equipped with a position input member.

[0150] In addition, when the laminated member has flexibility, the device of the present embodiment is preferably a flexible device.

[0151] In addition, in this specification, when "X~Y" (X and Y are arbitrary numbers) is described without special requirements, it means "X or more and Y or less", and also includes the meaning of "preferably greater than X" or "preferably less than Y". In addition, when "X or more" (X is an arbitrary number) is described without special requirements, it includes the meaning of "preferably greater than X", and when "Y or less" (Y is an arbitrary number) is described without special requirements, it also includes the meaning of "preferably less than Y".

[0152] Above, the embodiments of the present invention have been described, but the present invention is not limited to the above-mentioned embodiments, and various changes can be made within the scope of the present invention.

[0153] Examples

[0154] Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.

[0155] (Example 1)

[0156] 1. Preparation of (meth)acrylate polymer

[0157] 60 parts by mass of 2-ethylhexyl acrylate, 25 parts by mass of methyl methacrylate and 15 parts by mass of 2-hydroxyethyl acrylate were copolymerized to prepare a (meth)acrylate polymer (A). When the molecular weight of the obtained (meth)acrylate polymer (A) was measured by the method shown below, the weight-average molecular weight (Mw) was 700,000.

[0158] The weight-average molecular weight (Mw) is the weight-average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

[0159] (Measurement conditions)

[0160] ·GPC measurement device: manufactured by Tosoh Corporation, HLC-8020

[0161] ·GPC chromatographic column (passed through in the following order): manufactured by Tosoh Corporation

[0162] TSK guard column HXL-H

[0163] TSK gel GMHXL (×2)

[0164] TSK gel G2000HXLL

[0165] ·Measurement solvent: tetrahydrofuran

[0166] ·Measurement temperature: 40 °C

[0167] 2. Preparation of the pressure-sensitive adhesive composition

[0168] 100 parts by mass (in terms of solid content, the same hereinafter) of the above-obtained (meth)acrylate polymer (A), 0.25 parts by mass of an isocyanate-based crosslinking agent (B1) as a crosslinking agent (B) and 0.25 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed and stirred well, and at the same time, diluted with methyl ethyl ketone to obtain a coating solution of a pressure-sensitive adhesive composition having a solid content concentration of 50% by mass.

[0169] 3. Manufacture of the pressure-sensitive adhesive sheet

[0170] The coating solution of the pressure-sensitive adhesive composition obtained was applied to the release-treated surface of a heavy release type release sheet 11 so that the thickness after drying was 25 μm using a doctor blade coater. After application, heat treatment was carried out at 90 °C for 1 minute to cause a crosslinking reaction to form a coating layer composed of a pressure-sensitive adhesive having a crosslinked structure formed by the (meth)acrylate polymer (A) and the crosslinking agent (B).

[0171] Next, the coating layer on the release sheet 11 obtained above was bonded in contact with the release treatment surface of the light release type release sheet 12. Thereafter, it was cured for 7 days under the conditions of 23°C and 50% RH, thereby producing an adhesive sheet having an adhesive layer with a thickness of 25 μm. In addition, the thickness of the adhesive layer was the value measured using a constant pressure thickness gauge (manufactured by Teclock Corporation, product name "PG-02") in accordance with JIS K7130. Furthermore, in the obtained adhesive sheet, it was confirmed that the release force when the release sheet 11 was peeled off from the adhesive layer was greater than that of the release sheet 12.

[0172] (Examples 2 to 7, Comparative Examples 1 to 3)

[0173] The composition of the (meth)acrylate polymer (A), the type and blending amount of the crosslinking agent (B), the blending amount of the silane coupling agent, and the blending amount of the active energy ray curable component were changed according to the ratios shown in Table 1, and the thickness of the adhesive layer was changed to the thickness shown in Table 1. Except for this, the adhesive sheet was produced in the same manner as in Example 1. In addition, in Examples 4 and 6, an active energy ray curable component and a photopolymerization initiator were further added. In addition, in Comparative Example 1, no adhesive sheet was produced.

[0174] The physical properties of the obtained adhesive sheet were measured in the following manner.

[0175] (Evaluation of the gel fraction of the adhesive)

[0176] The adhesive layers produced in the examples and comparative examples were cut into a size of 50 mm × 50 mm, and the adhesive layer was wrapped in a polyester mesh (product name: Tetron mesh #200), and its mass was measured using a precision balance. The mass of the adhesive alone was calculated by subtracting the mass of the above mesh alone from the measured value. The mass at this time was defined as M1.

[0177] Thereafter, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. Thereafter, the mesh was taken out, air-dried for 24 hours in an environment with a temperature of 23°C and a relative humidity of 50%, and further dried in an oven at 80°C for 12 hours. After drying, its mass was measured using a precision balance. The mass of the adhesive alone was calculated by subtracting the mass of the above mesh alone from the measured value. The mass at this time was defined as M2. Using the obtained M1 and M2, the gel fraction was calculated by the following mathematical formula. The results are shown in Table 1.

[0178] Gel fraction (%) = (M2 / M1) × 100

[0179] In addition, for Examples 4 and 6, the gel fraction before and after irradiating the adhesive layer with ultraviolet rays (irradiated from the release sheet 1 side) was measured. The ultraviolet irradiation conditions are as follows.

[0180] <Ultraviolet irradiation conditions>

[0181] · Use a high-pressure mercury lamp

[0182] · The illuminance is 200 mW / cm 2 and the light quantity is 1000 mJ / cm 2

[0183] · The UV illuminance - light quantity meter uses "UVPF - A1" manufactured by EYE GRAPHICS

[0184] (Measurement of the adhesive strength of the adhesive layer)

[0185] Peel off the release sheet 12 from the adhesive sheets obtained in the examples and comparative examples, and attach the exposed adhesive layer to the adhesive layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "COSMOSHINE A4360", thickness: 100 μm) having an adhesive layer to obtain a laminate of release sheet 11 / adhesive layer / PET film. Cut the obtained laminate into a width of 25 mm and a length of 100 mm, and use this as a sample.

[0186] In an environment of 23°C and 50% RH, peel off the release sheet 11 from the above sample, attach the exposed adhesive layer to soda-lime glass (thickness: 1.1 mm), and then apply pressure at 0.5 MPa and 50°C for 20 minutes in an autoclave manufactured by Kurihara Seisakusho. After that, leave it for 24 hours under the conditions of 23°C and 50% RH, and then use a tensile testing machine (manufactured by Orientec Co., Ltd., product name "TENSILON") to measure the adhesive strength (N / 25 mm) under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180°. Measurements under conditions other than those described here are carried out in accordance with JIS Z0237:2009. The results are shown in Table 1.

[0187] In addition, for Examples 4 and 6, the adhesive strength after ultraviolet (UV) irradiation was also measured separately. Specifically, after the above autoclave treatment, the adhesive layer was irradiated with ultraviolet light from the soda-lime glass side under the same conditions as the measurement of the gel fraction. After that, leave it for 24 hours under the conditions of 23°C and 50% RH, and then measure the adhesive strength (N / 25 mm; after UV) in the same manner as above. The results are shown in Table 1.

[0188] (Storage modulus G' of the adhesive)

[0189] The adhesives produced in the examples and comparative examples were stacked in multiple layers to produce a laminate with a thickness of 800 μm (0.8 mm). Cylinders with a diameter of 8 mm (height 800 μm) were punched out from the resulting laminate of adhesive layers and used as samples for measuring the storage modulus.

[0190] For the samples for measurement, in accordance with JIS K7244-1, using a viscoelasticity measuring device (manufactured by Anton Paar, product name “MCR301”), the storage modulus was measured by the torsional shear method under the conditions of a measurement temperature range of -20 to 140 °C, a measurement frequency of 1 Hz, and a heating rate of 4 °C / min. The storage modulus at 23 °C was calculated from the measurement results. The results are shown in Table 1.

[0191] In addition, for Examples 4 and 6, the storage modulus after irradiating the adhesive layer with ultraviolet light (irradiated from the release sheet 11 side) was measured. The irradiation conditions for the ultraviolet light were the same as those for the measurement of the gel fraction.

[0192] (Pen drop test)

[0193] The release sheet 12 was peeled off from the adhesive sheets obtained in the examples and comparative examples, and the exposed adhesive layer was adhered to a PET film (manufactured by Toyobo Co., Ltd., product name “COSMOSHINE A 4360”, thickness: 38 μm, tensile strength: 250 MPa) as a substrate. Then, the release sheet 11 was peeled off from the adhesive sheet, and the exposed adhesive layer was attached to soda-lime glass (thickness: 700 μm) to obtain a laminate of substrate / adhesive layer / soda-lime glass. In addition, for Examples 4 and 6, the adhesive layer was irradiated with ultraviolet light (UV) (irradiated from the soda-lime glass side) under the same conditions as those for the measurement of the gel fraction.

[0194] The Figure 4 The pen drop test will be described. The obtained laminate 2 was placed with the substrate 13 side facing upward. A cylinder 30 with both ends open was placed perpendicular to the main surface 13a of the substrate 13 of the laminate 2, and one end 31 thereof was brought into contact with the main surface 13a of the substrate 13 of the laminate 2. From the other end 32, a ballpoint pen 40 whose total weight was adjusted to 100 g using a weight was dropped from a height of 30 cm from the main surface 13a of the substrate 13. At this time, the ballpoint pen 40 was dropped with the tip 41 facing downward so that the tip 41 came into contact with the main surface 13a of the substrate 13.

[0195] After the ballpoint pen 40 was dropped, the soda-lime glass 21 was evaluated for breakage based on the following criteria. The results are shown in Table 1.

[0196] ○: No cracks or fractures were generated on the glass.

[0197] ×: Cracks or fractures occurred on the glass.

[0198] (Pressing depth)

[0199] Peel off the release sheet 12 from a plurality of adhesive sheets manufactured in the examples and comparative examples, bring the release surfaces together with each other to stack multiple layers, and form a laminate of the adhesive layer with a thickness of 800 μm (0.8 mm). A PET film (manufactured by Toyobo Co., Ltd., product name "COSMOSHINE A4360", thickness: 38 μm, tensile strength: 250 MPa) is adhered to the surface of this laminate as a base material. Next, peel off the release sheet 11 from the laminate of the adhesive layer, and attach the exposed adhesive layer to a soda-lime glass (thickness: 700 μm) to obtain a laminate of base material / adhesive layer laminate / soda-lime glass. In addition, for Examples 4 and 6, ultraviolet rays (UV) are irradiated to the laminate of the adhesive layer under the same conditions as the measurement of the gel fraction (irradiated from the glass side). Using a texture analyzer (TA.XT.Plus manufactured by Stable Micro Systems), a load is continuously applied to the main surface of the adhesive layer exposed in the laminate at a pressing speed of 0.01 mm / second, and the pressing depth is measured at the time point when the load reaches 10 N. In Comparative Example 1, since there is no adhesive sheet, the test was not conducted. The results are shown in Table 1.

[0200] (Pressing pressure dispersibility)

[0201] In the pen drop test, a pressure measurement film is used to evaluate the dispersibility of the force applied to the glass. The pressure measurement film will change color when under pressure.

[0202] Place the laminate of base material / adhesive layer / soda-lime glass obtained in the pen drop test on the pressure measurement film (manufactured by Fujifilm Corporation, product name "Prescale ultra-low pressure LLLW") in such a way that the soda-lime glass surface of the laminate is in contact with the pressure measurement film. After that, let the ballpoint pen drop in the same procedure as the pen drop test.

[0203] After the ballpoint pen drops, evaluate the degree of color development of the pressure measurement film based on the following criteria. The results are shown in Table 1.

[0204] ○: The equivalent circle radius of the colored area of the pressure measurement film is 3 cm or more

[0205] △: The equivalent circle radius of the colored area of the pressure measurement film is 1 cm or more and less than 3 cm

[0206] ×: The equivalent circle radius of the colored area of the pressure measurement film is 1 cm or less

[0207] [Table 1]

[0208]

[0209] Details of the abbreviations and the like described in Table 1 are as follows.

[0210] ((Meth)acrylate polymer (A))

[0211] BA: n-Butyl acrylate

[0212] EA: Ethyl acrylate

[0213] AA: Acrylic acid

[0214] 2EHA: 2-Ethylhexyl acrylate

[0215] MMA: Methyl methacrylate

[0216] HEA: 2-Hydroxyethyl acrylate

[0217] IBXA: Isobornyl acrylate

[0218] ACMO: N-Acryloylmorpholine

[0219] PhEA: 2-Phenylethyl acrylate

[0220] EO9: Methoxypolyethylene glycol acrylate (C9)

[0221] 4HBA: 4-Hydroxybutyl acrylate

[0222] (Crosslinking agent (B))

[0223] B1: Isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "TAKENATE D-101E")

[0224] B2: Aluminum triacetylacetonate

[0225] B3: Isocyanate-based crosslinking agent (manufactured by Chugoku Chemical Industry Co., Ltd., product name "TD-75")

[0226] B4: Isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "TAKENATE D-170N")

[0227] (Silane coupling agent)

[0228] 3-Glycidoxypropyltrimethoxysilane

[0229] (Active energy ray curable component))

[0230] ε-Caprolactone-modified tris(2-acryloyloxyethyl) isocyanurate

[0231] (Photoinitiator)

[0232] Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide

[0233] As can be confirmed from Table 1, when the equivalent circle radius of the colored area in the pressing depth and pressure dispersion test of the adhesive is within the above range, the glass does not break in the pen drop test.

[0234] Industrial applicability

[0235] The adhesive of the present invention can be suitably used for bonding a member made of glass, for example, to other members.

[0236] Explanation of reference numerals

[0237] 1: Adhesive sheet; 10: Adhesive layer; 11: First release sheet; 12: Second release sheet; 2: Laminated member; 21: First member; 22: Second member.

Claims

1. An adhesive, wherein, When continuously pressing the surface of an adhesive with a thickness of 800 μm at a pressing speed of 0.01 mm / second and the pressing load reaches 10 N, the pressing depth is 140 μm or less. Through the pressure dispersion test shown below, the equivalent circle radius of the colored area of the pressure measurement film is 3 cm or more. Pressure dispersion test: Prepare a laminate formed by sequentially laminating a base material made of polyethylene terephthalate with a thickness of 38 μm, an adhesive, and a soda-lime glass with a thickness of 700 μm. Place the laminate on Prescale extra-low pressure LLLW manufactured by Fuji Film Co., Ltd. in such a way that the surface on the soda-lime glass side of the laminate contacts the pressure measurement film Prescale extra-low pressure LLLW. Drop a ballpoint pen weighing 100 g from a height of 30 cm from the surface on the base material side of the laminate onto the surface on the base material side of the laminate, and make the tip of the ballpoint pen with a tip diameter of 0.5 mm contact the surface on the base material side of the laminate, thereby applying pressure to the laminate.

2. The adhesive according to claim 1, wherein, The adhesive strength is 1 N / 25 mm or more and 100 N / 25 mm or less.

3. The adhesive according to claim 1 or 2, wherein, The gel fraction of the adhesive is 30% or more and 99% or less.

4. The adhesive according to claim 1 or 2, wherein, The adhesive is an acrylic adhesive.

5. An adhesive sheet, which is an adhesive sheet having an adhesive layer, wherein, The adhesive layer is composed of the adhesive according to claim 1 or 2.

6. The adhesive sheet according to claim 5, further comprising a release sheet, and the release sheet is provided on the main surface of the adhesive layer.

7. A laminated member including a first member made of glass, a second member, and an adhesive layer that bonds the first member and the second member to each other, wherein, The adhesive layer is composed of the adhesive according to claim 1 or 2.

8. The stacked member according to claim 7, wherein, The thickness of the first member is 40 μm or more and 2000 μm or less.

9. A display body, comprising the laminated member according to claim 7.

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