TWI731223B - Active energy ray curable adhesive sheet and laminate - Google Patents

Abstract

The present invention provides an active energy ray-curable adhesive sheet and a laminate having an adhesive layer that is excellent in conformability to unevenness and at the same time has excellent moisture and heat whitening resistance, durability, and blistering resistance. In order to solve the above problems, an active energy ray curable adhesive sheet 1 is provided, which is an adhesive sheet 1 having an adhesive layer 11 curable by active energy rays. The adhesive layer 11 is irradiated with active energy rays at 23 The ratio of the storage modulus at ℃ to the storage modulus at 23℃ before the active energy ray is irradiated to the adhesive layer 11 is 1.1-10. The two sides of the adhesive layer 11 are made of two pieces with a thickness of 1.1mm. The laminated body obtained by irradiating active energy rays through one side of the glass between the alkali-free glass is stored under the humid and hot conditions of 85℃ and 85%RH for 240 hours, and then from the normal temperature and humidity of 23℃ and 50%RH. The haze value (%) at the time of extraction is subtracted from the value of the haze value (%) before the hot and humid conditions, and the increase in the haze value after the hot and humid conditions is less than 5 points.

Description

Active energy ray curable adhesive sheet and laminate

The present invention relates to an adhesive sheet having an adhesive layer curable by active energy rays, and a laminate obtained using the adhesive layer of the adhesive sheet.

In recent years, various mobile electronic devices such as mobile phones and tablet terminals are equipped with displays using display modules such as liquid crystal elements, light-emitting diodes (LED elements), and organic electroplating luminescence (organic EL) elements.

In such a display, generally, a protective panel is formed on the surface side of the display module. Between the protective panel and the display module, when the protective panel is deformed due to external force, a gap will also be formed, so that the deformed protective panel will not touch the display module.

However, if the above-mentioned voids, that is, if the air layer exists, the difference in refractive index between the protective panel and the air layer, and the difference in refractive index between the air layer and the display module, will cause a large reflection loss of light, which may degrade the image quality of the display. problem.

Therefore, studies have proposed to improve the image quality of the display by filling the gap between the protective panel and the display module with an adhesive layer. However, on the display module side of the protective panel, a frame-shaped printed layer may exist as irregularities. If the adhesive layer does not follow the concavities and convexities, the adhesive layer floats from the vicinity of the concavities and convexities, thereby causing light reflection loss. Therefore, the above-mentioned adhesive layer is required to conform to irregularities.

In order to solve the above problems, Patent Document 1 describes that as an adhesive layer that fills the gap between the protective panel and the display module, the shear storage modulus (G') at 25°C and 1 Hz is 1.0×10 ⁵ Pa or less And, the gel fraction is 40% or more of the adhesive layer.

【Prior Technical Literature】

【Patent Literature】

[Patent Document 1] JP 2010-97070 A

In Patent Document 1, it is desired to reduce the storage modulus at room temperature in the adhesive layer to improve the conformability of unevenness. However, if the storage modulus at normal temperature is lowered as described above, the storage modulus at high temperature will be excessively lowered, causing problems under endurance conditions. For example, after the high-temperature and high-humidity conditions are implemented, when the temperature is restored to normal temperature and humidity, the adhesive layer may be whitened or bubbles may occur near the unevenness.

In addition, as the above-mentioned protective panel, a glass plate is generally used, but in accordance with recent requirements for thinning and weight reduction, a plastic plate may be used. In a high temperature environment, gas (outgassing) may be generated from the plastic plate. In the case of using this kind of plastic board, due to the above-mentioned degassing, air bubbles or floating or peeling (bubbles) may be generated between the plastic board and the adhesive layer.

The present invention was made in view of such current situation, and its object is to provide an active energy ray-curable adhesive having an adhesive layer that has excellent concavity and convexity followability, and at the same time, has excellent moisture and heat whitening resistance, durability, and blistering resistance. Sheets and laminates.

In order to achieve the above object, first, the present invention provides an active energy ray-curable adhesive sheet, which is an adhesive sheet containing an active energy ray-curable adhesive layer, characterized in that: the adhesive layer is irradiated The ratio of the storage modulus at 23°C after the active energy ray to the storage modulus at 23°C before the active energy ray is irradiated to the adhesive layer is 1.1-10; the two sides of the adhesive layer are 2 A piece of alkali-free glass with a thickness of 1.1mm is sandwiched, and the laminate obtained by irradiating active energy rays through one side of the glass is stored under damp heat conditions of 85°C and 85%RH for 240 hours, and then from 23°C to 50°C. The haze value (%) when taken out under normal temperature and humidity of %RH minus the value of the haze value (%) before the above damp and heat conditions, the increase in the haze value after the damp and heat conditions is less than 5.0 points (Invention 1).

Second, the present invention provides an active energy ray-curable adhesive sheet, which is an adhesive sheet containing an active energy ray-curable adhesive layer, characterized in that: the adhesive layer is irradiated with active energy rays after the The ratio of the storage modulus at 85°C to the storage modulus at 85°C before the active energy ray is irradiated to the above-mentioned adhesive layer is 1.1~10; the two sides of the above-mentioned adhesive layer have a thickness of 1.1mm The laminated body obtained by irradiating active energy rays through one side of the glass is sandwiched between the alkali-free glass, and stored at 85°C and 85%RH for 240 hours, and then from 23°C and 50%RH at room temperature. The haze value (%) at the time of taking out under humidity is subtracted from the value of the haze value (%) before the damp and heat conditions, and the increase in the haze value after the damp and heat conditions is less than 5.0 points.

In the above inventions (Inventions 1 and 2), the storage modulus of the adhesive layer at 23° C. before the active energy ray is irradiated is preferably 0.01 to 0.2 MPa (Invention 3).

In the above inventions (Inventions 1 to 3), the storage modulus at 23° C. of the adhesive layer after being irradiated with active energy rays is preferably 0.02 to 2 MPa (Invention 4).

In the above inventions (Inventions 1 to 4), the storage modulus of the adhesive layer at 85° C. before the active energy ray is irradiated is preferably 0.01 to 0.1 MPa (Invention 5).

In the above inventions (Inventions 1 to 5), the storage modulus of the adhesive layer at 85°C after being irradiated with active energy rays is preferably 0.02 to 0.5 MPa (Invention 6).

In the above inventions (Inventions 1 to 6), the thickness of the adhesive layer is preferably 50 to 400 μm (Invention 7).

In the above inventions (Inventions 1 to 7), the adhesive sheet includes two release sheets, and the adhesive layer is preferably sandwiched by the release sheets so as to contact the release surfaces of the two release sheets (Invention 8 ).

Thirdly, the present invention provides a laminated body characterized in that it includes two hard plates and an adhesive layer sandwiched between the two hard plates, and the adhesive layer is connected to the adhesive sheet (Invention 1~ The adhesive layer of Invention 8) is cured by irradiating active energy rays (Invention 9).

In the above invention (Invention 9), it is preferable that at least one of the hard plates has irregularities on the surface on the adhesive layer side (Invention 10).

In the above invention (Invention 10), the above-mentioned unevenness is preferably an unevenness due to the presence or absence of the printed layer (Invention 11).

In the above inventions (Invention 9 to Invention 11), at least one of the hard plates preferably includes a polarizing plate (Invention 12).

In the above inventions (Invention 9 to Invention 12), at least one of the above-mentioned hard boards preferably includes a plastic board (Invention 13).

In the above inventions (Inventions 9 to 11), one of the two hard boards is preferably a display module or a part thereof, and the other of the two hard boards is preferably on the surface on the side of the adhesive layer. Protective plate with frame-like projections and depressions (Invention 14).

In the above inventions (Invention 9 to Invention 14), the total light transmittance of the adhesive layer is preferably 80% or more.

Fourth, the present invention provides an adhesive sheet having a weight-average molecular weight of 200,000 to 900,000, as a monomer unit constituting a polymer, containing 5 to 20% by mass of a monomer having a carboxyl group or containing 15 Mass %-30% by mass (meth)acrylate copolymer (A) of a monomer having a hydroxyl group, active energy ray curable component (B) and bridging agent (C), the above active energy ray curable component (B) The content of, relative to 100 parts by mass of the above (meth)acrylate copolymer (A), is composed of 10 parts by mass to 50 parts by mass of the adhesive composition, and the thickness is 50μm~400μm. Agent layer.

In the above invention, by thermally bridging an adhesive composition containing a (meth)acrylate copolymer having a low weight average molecular weight and a predetermined amount of hydroxyl or carboxyl groups, the resulting adhesive layer has uneven conformability and It has excellent resistance to damp heat and whitening, and at the same time, it also has excellent durability. In addition, the adhesive composition contains a large amount of active energy ray curable components, and the adhesive layer is cured by the active energy ray irradiation. The adhesive layer cured in this way has excellent durability and blistering resistance.

In the above invention, the content of the bridging agent (C) in the adhesive composition is preferably 0.01 to 5 parts by mass relative to 100 parts by mass of the (meth)acrylate copolymer (A).

The adhesive layer of the active energy ray-curable adhesive sheet of the present invention has excellent concavity and convexity followability, and after active energy ray irradiation, it has excellent moisture and heat whitening resistance, durability, and blistering resistance. In a laminate obtained using such an active energy ray-curable adhesive sheet, even if there are irregularities on the adhesive layer side, the adhesive layer will follow the irregularities, so no floating or bubbles are generated near the irregularities Wait. In addition, in the above-mentioned laminate, the adhesive layer after active energy ray irradiation is also excellent in moisture and heat whitening resistance, durability, and blistering resistance.

1‧‧‧Active energy ray curable adhesive sheet

11‧‧‧Adhesive layer

12a, 12b‧‧‧Release sheet

2‧‧‧Layered body

21‧‧‧The first hard board

22‧‧‧Second hard board

3‧‧‧Printing layer

Fig. 1 is a cross-sectional view of an active energy ray-curable adhesive sheet according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view of a laminate according to an embodiment of the present invention.

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

〔Active energy ray curable adhesive sheet〕

As shown in Figure 1, the active energy ray-curable adhesive sheet 1 of this embodiment (in this specification, it may simply be referred to as "adhesive sheet"), consists of two release sheets 12a, 12b and The two peeling sheets 12a and 12b sandwich the adhesive layer 11 of the two peeling sheets 12a and 12b so that the peeling surfaces of the two peeling sheets 12a and 12b are in contact with each other. In addition, the peeling surface of the peeling sheet in this specification refers to the peeling surface of the peeling sheet, and includes both the surface that has been subjected to the peeling treatment and the surface that exhibits the peeling property even if the peeling treatment is not performed.

1. Adhesive layer

The above-mentioned adhesive layer 11 will contain a weight average molecular weight of 200,000 to 900,000, as a monomer unit constituting the polymer, containing 5 mass% to 20 mass% of a monomer having a carboxyl group (carboxyl group-containing monomer) or containing Adhesiveness of (meth)acrylate copolymer (A), active energy ray curable component (B) and bridging agent (C) of 15% to 30% by mass of monomers (hydroxyl-containing monomers) having hydroxyl groups The composition (hereinafter may be referred to as "adhesive composition P".) The active energy ray-curable adhesive layer constituted by thermal bridging. In addition, in this specification, the (meth)acrylic acid refers to both acrylic acid and methacrylic acid. The same goes for other similar terms.

The adhesive layer 11 in the adhesive sheet 1 is formed by thermally bridging the adhesive composition P. Specifically, the (meth)acrylate copolymer (A) passes through the bridging agent (C) to form a bridge status. On the other hand, the active energy ray-curable component (B) is not yet cured, and is present in the adhesive layer 11 in a state of being matched with the adhesive composition P. This active energy ray curable component (B) is polymerized and cured when the adhesive layer 11 is irradiated with active energy rays when the adhesive sheet 1 is used (when the adherend is bonded).

(1) (Meth) acrylate copolymer (A)

The (meth)acrylate copolymer (A) is the adhesive main agent in the adhesive composition P. The (meth)acrylate copolymer (A), as the monomer unit constituting the polymer, contains 5% to 20% by mass of carboxyl group-containing monomer, or 15% to 30% by mass of hydroxyl group-containing monomer . If the content of the carboxyl group-containing monomer or the hydroxyl group-containing monomer is in the above range, the bridge structure formed by the (meth)acrylate copolymer (A) and the cross-linking agent (C) becomes good, and the adhesive layer 11 is excellent The durability. In addition, the adhesive layer 11 obtained from the adhesive composition P containing the (meth)acrylate copolymer (A) in which the content of the carboxyl group-containing monomer or the hydroxyl group-containing monomer is in the above-mentioned range After the adhesive layer 11 is cured and subjected to high-temperature and high-humidity conditions (for example, 85°C and 85% RH, 240 hours), the whitening when returning to normal temperature and humidity is suppressed, that is, the whitening resistance is excellent in heat and humidity resistance . If the (meth)acrylate copolymer (A) contains a carboxyl group-containing monomer or a hydroxyl group-containing monomer as a monomer unit in the above-mentioned amount, a certain amount of carboxyl group or hydroxyl group will remain in the resulting adhesive. The carboxyl group and the hydroxyl group are hydrophilic functional groups. If this hydrophilic functional group is present in the adhesive in a certain amount, it is presumed that even if the adhesive is placed under high temperature and high humidity conditions, it will be immersed in the adhesive under the high temperature and high humidity conditions. When the moisture of the adhesive is restored to normal temperature and humidity, it is also easy to detach from the adhesive, and as a result, the whitening of the adhesive is suppressed.

In the (meth)acrylate copolymer (A), as the monomer unit, if the content of the carboxyl group-containing monomer is less than 5 mass%, or the content of the hydroxyl group-containing monomer is less than 15 mass%, the adhesive layer 11 , Especially the damp and heat resistance to whitening will be reduced. On the other hand, if the content of the carboxyl group-containing monomer exceeds 20% by mass, or the content of the hydroxyl group-containing monomer exceeds 30% by mass, the coating workability of the adhesive composition P will deteriorate.

From the above point of view, the (meth)acrylate copolymer (A), as the monomer unit constituting the polymer, preferably contains 7 mass% to 15 mass%, especially 8 mass% to 12 mass%. The carboxyl group monomer may contain 17% by mass to 28% by mass, especially 20% by mass to 25% by mass of hydroxyl group-containing monomers.

Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among them, from the viewpoints of the reactivity of the carboxyl group in the obtained (meth)acrylate polymer (A) with the bridging agent (B) and the copolymerizability with other monomers, (meth)acrylic acid is preferred, and particularly preferred For acrylic. These may be used alone or in combination of two or more kinds.

Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, (meth) Hydroxyalkyl (meth)acrylates such as 2-hydroxybutyl acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and the like. Among them, from the viewpoint of the reactivity of the hydroxyl group in the obtained (meth)acrylate polymer (A) with the cross-linking agent (B) and the copolymerizability with other monomers, (meth)acrylic acid 2- Hydroxyethyl ester. These may be used alone or in combination of two or more kinds.

The (meth)acrylate copolymer (A), as the monomer unit constituting the polymer, is preferably an alkyl (meth)acrylate having 1 to 20 carbon atoms containing an alkyl group, and is particularly preferred as the main The ingredients are contained. Thus, the resulting adhesive can exhibit excellent adhesiveness.

Examples of alkyl (meth)acrylates having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, and propylene (meth)acrylate. Base ester, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isopropyl (meth)acrylate Octyl ester, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, (methyl) ) Stearyl acrylate, etc. Among them, from the viewpoint of further improving adhesiveness, (meth)acrylates having an alkyl group of 1 to 8 carbon atoms are preferred, and methyl (meth)acrylate and n-butyl (meth)acrylate are particularly preferred. Ester and 2-ethylhexyl (meth)acrylate. Moreover, these can be used individually or in combination of 2 or more types.

The (meth)acrylate copolymer (A), as the monomer unit constituting the polymer, is preferably an alkyl (meth)acrylate having 1 to 20 carbon atoms containing 50% by mass or more of an alkyl group, and is particularly preferred The content is 60% by mass or more, more preferably 70% by mass or more. In addition, the upper limit of the content of the alkyl (meth)acrylate having 1 to 20 carbon atoms of the alkyl group is preferably the remainder excluding the carboxyl group-containing monomer and the hydroxyl group-containing monomer.

The (meth)acrylate copolymer (A) may contain other monomers as necessary as monomer units constituting the polymer. As other monomers, even if it is to not hinder the reaction of the carboxyl group-containing monomer or the hydroxyl group-containing monomer, it should preferably not contain a monomer having a reactive functional group. Examples of such monomers include (meth)acrylic acid alkoxyalkyl esters such as (meth)acrylic methoxyethyl, (meth)acrylic ethoxyethyl, and the like; (meth) Aliphatic (meth)acrylates such as cyclohexyl acrylate; non-bridging acrylamides such as acrylamide and methacrylamide; (meth)acrylic acid N,N-dimethylaminoethyl (Meth)acrylates with non-bridging tertiary amino groups such as N,N-dimethylaminopropyl (meth)acrylic acid; vinyl acetate, styrene, etc. These may be used alone or in combination of two or more kinds.

The polymerization method of the (meth)acrylate copolymer (A) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth)acrylate copolymer (A) is 200,000 to 900,000, preferably 250,000 to 700,000. 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.

If the weight average molecular weight of the main component (meth)acrylate copolymer (A) of the adhesive composition P is small as described above, the adhesive layer 11 obtained by thermally bridging the adhesive composition P , Has excellent concavity and convexity followability. If the weight average molecular weight of the (meth)acrylate copolymer (A) exceeds 900,000, the unevenness followability will decrease. On the other hand, if the weight average molecular weight of the (meth)acrylate copolymer (A) is less than 200,000, the durability of the adhesive layer 11 after active energy ray irradiation decreases. From the above viewpoint, the weight average molecular weight of the (meth)acrylate copolymer (A) is particularly preferably 300,000 to 500,000 from the viewpoint of unevenness and durability, and from the viewpoint of blister resistance, The weight average molecular weight of the (meth)acrylate copolymer (A) is particularly preferably 500,000 to 700,000.

Moreover, in the adhesive composition P, the (meth)acrylate copolymer (A) may be used individually by 1 type, and may be used in combination of 2 or more types.

(2) Active energy ray curable component (B)

The adhesive layer 11 formed by the adhesive composition P containing the active energy ray-curable component (B) is an active energy ray-curable adhesive layer. The adhesive layer 11 contains the active energy ray-curable component (B), so that it is excellent in unevenness and durability.

The active energy ray curable component (B) is not particularly limited as long as it is a component that is cured by active energy ray irradiation without impairing the effects of the present invention, and may be any of monomers, oligomers, and polymers. One kind, or a mixture of them. Among them, preferably, a polyfunctional acrylate monomer having a molecular weight of less than 1,000, which is excellent in compatibility with the (meth)acrylate copolymer (A), etc., is used.

Examples of polyfunctional acrylate monomers with a molecular weight of less than 1000 include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and neopentyl diacrylate. Alcohol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth) Acrylate, dicyclopentyl di(meth)acrylate, caprolactone modified dicyclopentenyl di(meth)acrylate, ethylene oxide modified phosphoric acid di(meth)acrylate, di(meth)acrylate Bifunctional type such as acryloxyethyl) isocyanate, allylated cyclohexyl di(meth)acrylate, etc.; trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate , Propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, epoxy propylene modified trimethylolpropane tri(meth)acrylate, tris(propylene oxyethyl) ) Isocyanate, ε-caprolactone modified tris-(2-(meth)acryloxyethyl) isocyanate, etc.; trifunctional type; diglycerol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylic acid 4-functional type such as esters; 5-functional type such as propionic acid-modified dipentaerythritol penta(meth)acrylate; dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate The 6-functional type and so on. These may be used individually by 1 type, and may be used in combination of 2 or more types.

As the active energy ray-curable component (B), an active energy ray-curable acrylic oligomer can also be used. The acrylic oligomer preferably has a weight average molecular weight of 50,000 or less. Examples of such acrylic oligomers include polyester acrylates, epoxy acrylates, urethane acrylates, polyether acrylates, polybutadiene acrylates, and silicone acrylates.

Here, the polyester acrylate oligomer, for example, can be obtained by polycondensing a polycarboxylic acid and a polyhydric alcohol by using (meth)acrylic acid to obtain the hydroxyl groups and esters of the polyester oligomer having hydroxyl groups at both ends. Alternatively, it can be obtained by esterifying the hydroxyl group at the end of the oligomer obtained by adding alkylene oxide to a polycarboxylic acid with (meth)acrylic acid. The epoxy acrylate-based oligomer can be obtained, for example, by reacting (meth)acrylic acid on the ethylene oxide ring of a bisphenol-type epoxy resin and a novolak-type epoxy resin, and esterifying it. In addition, a carboxy-modified epoxy acrylate oligomer obtained by partially modifying the epoxy acrylate oligomer with a dibasic carboxylic anhydride can also be used. The urethane acrylate oligomer can be obtained, for example, by esterifying (meth)acrylic acid a urethane oligomer obtained by a reaction between a polyether polyol and a polyester polyol and a polyisocyanate. The polyol acrylate oligomer can be obtained by esterifying the hydroxyl group of a polyether polyol with (meth)acrylic acid.

The weight average molecular weight of the acrylic oligomer is preferably 50,000 or less, particularly preferably 500 to 50,000, and still more preferably 3,000 to 40,000. These acrylic oligomers may be used alone or in combination of two or more kinds.

In addition, as the active energy ray-curable component (B), an adduct acrylate polymer obtained by introducing a group having a (meth)acryloyl group into the side chain can also be used. Such an adduct acrylate polymer can be made to have a (meth)acrylic acid group and a bridging functional group by using a copolymer of (meth)acrylate and a monomer having a bridging functional group in the molecule. The compound of the reacted group is obtained by reacting a part of the bridging functional group of the copolymer.

As the above-mentioned (meth)acrylates, alkyl (meth)acrylates having 1 to 20 carbon atoms containing an alkyl group are preferred. Examples thereof include methyl (meth)acrylate and ethyl (meth)acrylate. Base ester, propyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, (methyl) ) 2-ethylhexyl acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, myristyl (meth)acrylate, ( Cetyl meth)acrylate, stearyl (meth)acrylate and the like. These may be used alone or in combination of two or more kinds.

The monomer having a bridging functional group in the molecule preferably contains at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and an amide group as the functional group. As the above-mentioned monomers, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate can be cited. -Hydroxyalkyl (meth)acrylates such as hydroxybutyl ester, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc.; N-methylolacrylamide, etc. Acrylic amines; (meth)acrylic acid monomethylaminoethyl ester, (meth)acrylic acid monoethylaminoethyl ester, (meth)acrylic acid monomethylaminopropyl ester, (meth)acrylic acid Monoalkylaminoalkyl (meth)acrylates such as monoethylaminopropyl ester; ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid Wait. These monomers may be used alone or in combination of two or more kinds.

As a compound having a group that reacts with a (meth)acryloyl group and a bridging functional group, for example, 2-methacryloyloxyethyl isocyanate, methacrylic acid 2-(0-[1 '-Methylpropyleneamino]carboxyamino)ethyl, 2-[(3,5-dimethylpyridino)carbonylamino]ethyl methacrylate, 1,1-(bisacryloxymethyl) Ethyl isocyanate, 2-propylene oxyethyl isocyanate, 2- propylene oxyethyl succinate, 2- propylene oxyethyl hexahydrophthalimide, ω-carboxy-polycaprolactone monomer Acrylate, phthalic acid monohydroxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, etc. These compounds may be used alone or in combination of two or more kinds.

The weight average molecular weight of the adduct acrylate polymer is preferably about 50,000 to 900,000, and particularly preferably about 100,000 to 300,000.

The active energy ray curable component (B) may be selected from the above-mentioned polyfunctional acrylate monomers, acrylate oligomers and adduct acrylate polymers, or two or more of them may be used. It can also be used in combination with active energy ray curable components other than these.

The content of the active energy ray curable component (B) in the adhesive composition P needs to be 10 parts by mass to 50 parts by mass relative to 100 parts by mass of the (meth)acrylate copolymer (A), and is preferably 15 parts by mass to 45 parts by mass, particularly preferably 25 parts by mass to 40 parts by mass. If the content of active energy ray curable component (B) is more than 10 parts by mass, the adhesive layer 11 after active energy ray irradiation has an increased cohesive force, and even if the plastic plate degass in a high temperature environment, bubbles can be suppressed Or floating or peeling occurs, and it has excellent blistering resistance. That is, if the content of the active energy ray curable component (B) is less than 10 parts by mass, the adhesive layer 11 after active energy ray irradiation cannot be excellent in blister resistance. On the other hand, if the content of the active energy ray curable component (B) exceeds 50 parts by mass, the adhesive force of the adhesive layer 11 before active energy ray irradiation becomes too high, and the sheet will be released from the adhesive layer 11 The smooth peeling of 12a and 12b becomes difficult, and when the peeling sheets 12a and 12b are peeled off, the adhesive layer 11 may be damaged. In addition, the adhesive layer 11 after active energy ray irradiation has an adhesive force of 10 N/25 mm or more (to the glass substrate), so that the bonding state between the rigid plates can be firmly maintained.

(3) Bridging agent (C)

The adhesive composition P contains a bridging agent (C) to bridge the (meth)acrylate copolymer (A) to form a three-dimensional network structure, and to improve the cohesive force of the resulting adhesive. In addition, after active energy rays are irradiated, the adhesive may also be imparted with durability.

As the cross-linking agent (C), any cross-linking agent that is reactive with the reactive functional group (carboxyl group or hydroxyl group) possessed by the (meth)acrylate copolymer (A) may be used. For example, an isocyanate-based cross-linking agent can be mentioned. , Epoxy cross-linking agent, amine cross-linking agent, melamine cross-linking agent, aziridine cross-linking agent, hydrazine cross-linking agent, aldehyde cross-linking agent, oxaline cross-linking agent, metal alkoxide cross-linking agent, metal chelate Compound bridging agents, metal salt bridging agents, ammonium salt bridging agents, etc. The bridging agent (C) may be used alone or in combination of two or more kinds.

When the (meth)acrylate copolymer (A) contains a carboxyl group-containing monomer, it is preferable to use at least one selected from epoxy-based bridging agents having excellent reactivity with carboxyl groups and isocyanate-based bridging agents as the bridging agent (C ), it is particularly preferable to use epoxy-based bridging agents. When the (meth)acrylate copolymer (A) contains a hydroxyl group-containing monomer, it is preferable to use an isocyanate-based bridging agent having excellent reactivity with the hydroxyl group.

Examples of epoxy-based bridging agents include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl metadi Toluene diamine, ethylene glycol diglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine, etc.

The isocyanate-based bridging agent is a bridging agent containing at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylphenyl diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; isophorone Alicyclic polyisocyanates such as diisocyanate, hydrogenated diphenylmethane diisocyanate, etc.; and these biuret bodies and isocyanate bodies; further examples include ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor Sesame oil and the like are used as adducts with low-molecular-weight active hydrogen compounds.

The content of the bridging agent (C) in the adhesive composition P is preferably 0.01 parts by mass to 5 parts by mass, and particularly preferably 0.05 parts by mass relative to 100 parts by mass of the (meth)acrylate copolymer (A). 1 part by mass. If the content of the bridging agent (C) is 0.01 parts by mass or more, the adhesive after active energy ray irradiation can provide an effect of improving durability. If the content of the bridging agent (C) exceeds 5 parts by mass, the degree of bridging becomes excessive, and the conformability of the resulting adhesive may be reduced. In addition, a large amount of the carboxyl groups or hydroxyl groups of the (meth)acrylate copolymer (A) reacts with the bridging agent (C), and the amount of carboxyl groups or hydroxyl groups remaining in the adhesive decreases, and the above-mentioned humidity and heat whitening resistance may be reduced. Further from the above viewpoint, from the viewpoint of optimizing durability, the content of the bridging agent (C) is preferably 0.05 to 0.4 parts by mass, and from the viewpoint of optimizing the blistering resistance, the bridging agent (C) The content of is preferably 0.3 parts by mass to 1 part by mass.

(4) Photopolymerization initiator (D)

When ultraviolet rays are used as the active energy rays irradiated to the adhesive layer 11, the adhesive composition P further preferably contains a photopolymerization initiator (D). In this way, by containing the photopolymerization initiator (D), the active energy ray curable component (B) can be effectively cured, and the polymerization curing time and the irradiation amount of the active energy ray can be reduced.

As such a photopolymerization initiator (D), for example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, Benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylbenzene Ethyl ketone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl] -2-morphine-propane-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone , 4,4'-Diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2 -Methyl phenoxanthone, 2-ethyl phenoxanthone, 2-chloro phenoxanthone, 2,4-dimethyl phenoxanthone, 2,4-diethyl phenoxanthone, benzyl dimethyl ketone Ketone, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]acetone], 2 , 4,6-Trimethylbenzyl-diphenyl-phosphine oxide and so on. These may be used alone or in combination of two or more kinds.

The photopolymerization initiator (D) is preferably used in an amount ranging from 4 parts by mass to 12 parts by mass relative to 100 parts by mass of the active energy ray curable component (B).

(5) Various additives

Adhesive composition P can be added with various additives commonly used in acrylic adhesives, such as silane coupling agents, antistatic agents, adhesion imparting agents, oxidation inhibitors, ultraviolet absorbers, light Stabilizers, flame retardants, fillers, refractive index modifiers, etc.

In particular, from the viewpoint of improving durability, it is preferable to add a silane coupling agent as an additive to the adhesive composition P. The silane coupling agent is an organosilicon compound having at least one alkoxysilyl group in the molecule, and preferably has good compatibility with the (meth)acrylate copolymer (A). In addition, when the adhesive sheet 1 is used for optical applications, it is preferably a silane coupling agent having light permeability.

Examples of the above-mentioned silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyl trimethoxysilane, vinyl triethoxysilane, methacryloxypropyl trimethoxysilane, and 3 -Glycidoxytrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and other silicon compounds with epoxy structure, 3-mercaptopropyltrimethoxysilane, 3 -Mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane and other mercapto group-containing silicon compounds, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)- Amino-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, Containing 3-isocyanate propyl triethoxy silane, or at least one of these and methyl triethoxy silane, ethyl triethoxy silane, methyl trimethoxy silane, ethyl trimethoxy silane, etc. Condensates of alkyl silicon compounds, etc. These may be used individually by 1 type, and may be used in combination of 2 or more types.

The addition amount of the silane coupling agent is preferably 0.01 parts by mass to 1.0 parts by mass, and particularly preferably 0.05 parts by mass to 0.5 parts by mass relative to 100 parts by mass of the (meth)acrylate copolymer (A).

(6) Manufacturing of adhesive composition

Adhesive composition P can be obtained by manufacturing (meth)acrylate copolymer (A), and the obtained (meth)acrylate copolymer (A), active energy ray curable component (B) and bridging agent ( C) It is produced by mixing, and at the same time, adding a photopolymerization initiator (D) and/or additives as necessary.

The (meth)acrylate copolymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a normal radical polymerization method. The polymerization of the (meth)acrylate copolymer (A) can be carried out by a solution polymerization method or the like using a polymerization initiator as necessary. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like, and two or more of them may be used in combination.

As the polymerization initiator, azo compounds, organic peroxides, and the like can be cited, and two or more of them can be used simultaneously. Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane 1 -Nitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), Dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxyl Methylpropionitrile), 2,2'-azobis[2-(2-imidolin-2-yl)propane] and the like.

Examples of organic peroxides include benzyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxy dicarbonate, and di-n-propyl peroxy. Dicarbonate, bis(2-ethoxyethyl) peroxydicarbonate, tert-butyl peroxyneoctoate, tert-butyl peroxypivalate, (3,5,5-trimethyl Hexyl) peroxide, dipropylene peroxide, diacetyl peroxide, etc.

In addition, in the above-mentioned polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by combining a chain transfer agent such as 2-mercaptoethanol.

After obtaining the (meth)acrylate copolymer (A), in the solution of the (meth)acrylate copolymer (A), add the active energy ray curable component (B), the bridging agent (C) and if necessary The photopolymerization initiator (D) and additives were thoroughly mixed to obtain an adhesive composition P.

(7) Formation of adhesive layer

The adhesive layer 11 is formed by thermally bridging the adhesive composition P. That is, the bridging of the adhesive composition P is performed by heat treatment. In addition, this heating treatment can also be used as a drying treatment after the adhesive composition P is applied.

The heating temperature of the heat treatment is preferably 50°C to 150°C, particularly preferably 70°C to 120°C. In addition, the heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes. After the heat treatment, it can be left at room temperature (for example, 23°C, 50% RH) for an aging period of about 1 to 2 weeks as needed. When the aging period is required, after the aging period is passed; when the aging period is not required, the adhesive layer is formed after the heat treatment is completed.

By the above-mentioned heat treatment (and aging) interposing the bridging agent (C), the (meth)acrylate copolymer (A) is bridged well.

The thickness (value measured based on JIS K7130) of the formed adhesive layer 11 is 50 μm to 400 μm, preferably 70 μm to 300 μm, and particularly preferably 90 μm to 250 μm. In addition, the adhesive layer 11 may be formed by a single layer, or may be formed by stacking a plurality of layers.

If the thickness of the adhesive layer 11 is less than 50 μm, sufficient concavity and convexity followability cannot be obtained, and if the thickness of the adhesive layer 11 exceeds 400 μm, the workability is reduced.

2. Peel off sheet

As the release sheets 12a, 12b, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, poly Ethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, vinyl acetate vinyl film, ionomer resin film, ethylene-(former Base) acrylic copolymer film, ethylene-(meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. In addition, these bridging films can also be used. Furthermore, these laminated films may also be used.

It is preferable that the peeling surface (especially the surface contacting the adhesive layer 11) of the said peeling sheet 12a, 12b is given a peeling process. Examples of release agents used in the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents. In addition, among the release sheets 12a and 12b, it is preferable that the release sheet on one side is a heavy release type release sheet with a large release force, and the release sheet on the other side is a light release type release sheet with a small release force.

The thickness of the release sheets 12a and 12b is not particularly limited, but is usually about 20 μm to 150 μm.

3. Manufacture of bonding sheet

As an example of manufacturing the adhesive sheet 1, on the peeling surface of one peeling sheet 12a (or 12b), the coating solution of the adhesive composition P is applied and heated, and the adhesive composition P is thermally bridged, After the coating layer is formed, the release surface of the other release sheet 12b (or 12a) is polymerized on the coating layer. When the aging period is required, the aging period is reserved; when the aging period is not required, the coating layer directly becomes the adhesive layer 11. Thus, the above-mentioned adhesive sheet 1 was obtained. In addition, at this stage, no active energy rays are irradiated.

As another example of manufacturing the adhesive sheet 1, on the release surface of one release sheet 12a, the coating solution of the adhesive composition P is coated and heated, and the adhesive composition P is thermally bridged to form a coating layer , The release sheet 12a with the coating layer was obtained. In addition, on the peeling surface of the other peeling sheet 12b, the coating solution of the adhesive composition P is applied and heated, and the adhesive composition P is thermally bridged to form a coating layer to obtain a coating layer. The peeling sheet 12b. After that, the release sheet 12a with the coating layer and the release sheet 12b with the coating layer are bonded together so that the two coating layers are in contact with each other. In the case where the aging period is required, the aging period is retained; when the aging period is not required, the above-mentioned laminated coating layer directly becomes the adhesive layer 11. Thus, the above-mentioned adhesive sheet 1 was obtained. According to this manufacturing example, even when the adhesive layer 11 is thick, it can be manufactured stably.

As a method of applying the coating liquid of the adhesive composition P, for example, a bar coating method, a knife coating method, a roll coating method, a plate coating method, a die coating method, a gravure coating method, etc. can be used.

4. Physical properties

The ratio of the storage modulus at 23°C after the active energy ray is irradiated to the adhesive layer 11 to the storage modulus at 23°C before the active energy ray is irradiated to the adhesive layer 11 (active energy ray irradiation The subsequent storage modulus/the storage modulus before active energy ray irradiation) is preferably 1.1-10, particularly preferably 1.2-7. In addition, the storage modulus in this specification is a value measured by the torsion shear method at a measurement frequency of 1 Hz based on JIS K7244-6.

As described above, after active energy ray irradiation (after curing), the storage modulus of the adhesive layer 11 at 23° C. increases, and the cured adhesive layer 11 is excellent in durability and unevenness followability. In addition, from the above viewpoint, the ratio of the storage modulus is particularly preferably 3 to 7 from the viewpoint of blister resistance.

In addition, the ratio of the storage modulus at 85°C after the active energy ray is irradiated to the adhesive layer 11 to the storage modulus at 85°C before the active energy ray is irradiated to the adhesive layer 11 (active energy The storage modulus after radiation/storage modulus before active energy radiation) is preferably 1.1-10, particularly preferably 1.3-7. In addition, from the above viewpoint, the ratio of the storage modulus is particularly preferably 3-7 from the viewpoint of blistering resistance.

As described above, after active energy ray irradiation (after curing), the storage modulus of the adhesive layer 11 at 85° C. increases, and the cured adhesive layer 11 has excellent durability even at high temperatures.

If the ratio of the storage modulus at 23°C or 85°C is less than 1.1, the durability improvement effect described above may not be obtained. On the other hand, if the ratio of the storage modulus at 23° C. or 80° C. exceeds 10, the adhesive force of the cured adhesive layer 11 decreases, and there is a possibility that sufficient durability cannot be obtained.

The storage modulus of the adhesive layer 11 before active energy ray irradiation at 23° C. is preferably 0.01 MPa to 0.2 MPa, particularly preferably 0.04 MPa to 0.15 MPa, and still more preferably 0.07 MPa to 0.1 MPa. In addition, the storage elastic modulus of the adhesive layer 11 before active energy ray irradiation at 85° C. is preferably 0.01 MPa to 0.1 MPa, particularly preferably 0.01 MPa to 0.06 MPa, and still more preferably 0.02 MPa to 0.04 MPa. The adhesive layer 11 before the active energy ray irradiation has the storage modulus as described above, and thus has excellent unevenness followability.

The storage modulus at 23° C. of the adhesive layer 11 after active energy ray irradiation is preferably 0.02 MPa to 2 MPa, particularly preferably 0.05 MPa to 1 MPa, and still more preferably 0.1 MPa to 0.6 MPa. In addition, the storage modulus at 85° C. of the adhesive layer 11 after active energy ray irradiation is preferably 0.02 MPa to 0.5 MPa, particularly preferably 0.02 MPa to 0.2 MPa, and still more preferably 0.03 MPa to 0.1 MPa. The adhesive layer 11 after the active energy ray irradiation has the storage elastic modulus as described above, so that it is excellent in durability and blistering resistance.

In the above adhesive sheet 1, the adhesive layer 11 before active energy ray irradiation is excellent in conformability to unevenness. Therefore, when the adherend has unevenness, the unevenness and the adhesive layer 11 are unlikely to appear between the unevenness. When voids or bubbles are generated, the adhesive layer 11 can fill up the unevenness. In addition, the adhesive layer 11 is cured by the irradiation of active energy rays, and has excellent moisture and heat whitening resistance, durability, and blistering resistance.

The adhesive layer 11 of the adhesive sheet 1 of this embodiment is preferably used for bonding two hard plates to each other as described later.

〔Laminated body〕

As shown in FIG. 2, the laminate 2 of this embodiment is composed of a first hard board 21, a second hard board 22, and an adhesive sandwiched between the first hard board 21 and the second hard board 22. The adhesive layer 11 is formed. In addition, in the layered product 2 of this embodiment, the first hard plate 21 has unevenness on the surface on the adhesive layer 11 side, specifically, has unevenness due to the presence or absence of the printed layer 3.

The first hard board 21 and the second hard board 22 are not particularly limited as long as the adhesive layer 11 can be adhered. In addition, the first hard board 21 and the second hard board 22 may be the same material or different materials.

As the first hard board 21 and the second hard board 22, for example, in addition to a glass plate, a plastic plate, a metal plate, a semiconductor plate, etc., a laminate of these, or a plate-shaped hard plate such as a display module, a solar cell module, etc. Products, etc. Since the adhesive layer 11 in this embodiment is excellent in blister resistance, it is preferable that at least one of the 1st hard board 21 and the 2nd hard board 22 contains a plastic board.

The glass plate is not particularly limited, and examples include chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium strontium glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate Salt glass and so on. The thickness of the glass plate is not particularly limited, but is usually 0.1 mm to 5 mm, preferably 0.2 mm to 2 mm.

There is no particular limitation on the above-mentioned plastic sheet, and examples thereof include acrylic sheets and polycarbonate sheets. The thickness of the plastic plate is not particularly limited, but is usually 0.2 mm to 5 mm, preferably 0.4 mm to 3 mm.

In addition, various functional layers (transparent conductive film, metal layer, silicon dioxide layer, hard coat layer, anti-glare layer, etc.) may be formed on one or both surfaces of the glass plate and plastic plate, and metal wiring may be formed. There may be a build-up of optical components.

Examples of the above-mentioned optical members include polarizing plates (polarizing films), polarizers, retardation plates (retardation films), viewing angle compensation films, brightness-enhancing films, contrast-enhancing films, liquid crystal polymer films, diffusion films, and hard coatings. Layer film, semi-transmissive reflective film, etc.

In addition, as the above-mentioned display module, for example, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroplating luminescence (organic EL) module, electronic paper, etc. can be cited. In addition, these display modules usually have a laminate of the above-mentioned glass plates, plastic plates, and optical components. For example, there is a stack of polarizing plates in an LCD module, and the polarizing plate forms one side surface of the LCD module.

In the laminate 2 of the present embodiment, at least one of the first hard plate 21 and the second hard plate 22 preferably has a polarizing plate. In addition, in the laminate 2 of the present embodiment, it is preferable that the second hard plate 22 is a display module or a part thereof (for example, an optical member such as a polarizing plate), and the first hard plate 21 is a protective plate made of a plastic plate or the like. At this time, the printing layer 3 is generally formed in a frame shape on the adhesive layer 11 side of the first hard board 21.

The material constituting the printing layer 3 is not particularly limited, and known materials for printing are used. The thickness of the printed layer 3, that is, the height of the unevenness, is preferably 3 μm to 45 μm, particularly preferably 5 μm to 35 μm, still more preferably 7 μm to 25 μm, and even more preferably 7 μm to 15 μm.

In addition, the thickness of the printed layer 3 (height of the unevenness) is preferably 3% to 30% of the thickness of the adhesive layer 11, particularly preferably 3.2% to 20%, and still more preferably 3.5% to 15%. Thereby, the adhesive layer 11 can surely follow the unevenness due to the printed layer 3, and no floating or bubbles or the like will occur in the vicinity of the unevenness.

The adhesive layer 11 of the laminate 2 of this embodiment is cured by curing the adhesive layer 11 in the adhesive sheet 1 irradiated with active energy rays. The active energy ray here means that an electromagnetic wave or a charged particle beam has an energy quantum. Specifically, ultraviolet rays, electron beams, and the like can be cited. Among the active energy rays, ultraviolet rays, which are easy to handle, are particularly preferred.

The irradiation of ultraviolet rays can be performed by a high-pressure mercury lamp, a Fusion H lamp, a xenon lamp, etc., and the irradiation amount of ultraviolet rays is preferably about 50 mW/cm ² to 1000 mW/cm ² . Further, the light amount is preferably ^{50mJ / cm 2 ~ 10000mJ / cm} 2, particularly preferably ^{80mJ / cm 2 ~ 5000mJ / cm} 2, more preferably ^{200mJ / cm 2 ~ 2000mJ / cm} 2. On the other hand, the electron beam irradiation can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 krad to 1000 krad.

When the adhesive layer 11 of the adhesive sheet 1 is irradiated with active energy rays, the active energy ray-curable component (B) is polymerized and cured. The adhesive layer 11 cured by the irradiation of active energy rays is excellent in durability, resistance to damp heat whitening, and resistance to blister.

The laminate 2 is manufactured. As an example, first, one peeling sheet 12a (or 12b) of the adhesive sheet 1 is peeled off, and the adhesive layer 11 exposed on the adhesive sheet 1 and the first hard board 21 (or the second hard board) are peeled off. The board 22) is attached. Next, from the adhesive layer 11 of the adhesive sheet 1, the other release sheet 12b (or 12a) is peeled, and the exposed adhesive layer 11 of the adhesive sheet 1 and the second hard board 22 (or the first hard board) are peeled off. Plate 21) is attached.

When bonding the adhesive layer 11 and the first hard board 21 in the above steps, the adhesive layer 11 has excellent unevenness followability, and it is difficult to generate voids between the unevenness of the printed layer 3 and the adhesive layer 11. The adhesive layer 11 can fill up the unevenness.

Then, the adhesive layer 11 is irradiated with active energy rays from either side of the first hard board 21 or the second hard board 22 to cure the adhesive layer 11. In this case, the hard plate on the side irradiated with active energy rays needs to have active energy ray permeability.

In the laminate 2 described above, since the adhesive layer 11 before active energy ray irradiation is excellent in conformability to irregularities, it is difficult to generate voids or bubbles between the irregularities of the printed layer 3 and the adhesive layer 11. In addition, the adhesive layer 11 cured by the irradiation of the active energy ray, after being subjected to high-temperature and high-humidity conditions, the whitening at the time of returning to normal temperature is suppressed, and the whitening resistance to moisture and heat is excellent. In addition, the adhesive layer 11 irradiated with active energy rays can prevent the occurrence of bubbles and the like in the vicinity of the unevenness even under high-temperature and high-humidity conditions, and is excellent in durability. In addition, at least one of the first hard board 21 and the second hard board 22 may include a plastic board. Even if the plastic board is degassed under high temperature conditions, the adhesive layer 11 irradiated with active energy rays is resistant to water bubbles. The performance is also excellent, so the occurrence of bubbles, floating, and peeling is suppressed.

The excellent moisture and heat whitening resistance of the adhesive layer 11 cured by irradiation with active energy rays can be evaluated as follows. For example, the two sides of the adhesive layer 11 are sandwiched by two sheets of alkali-free glass with a thickness of 1.1 mm, and at least one side of the alkali-free glass is irradiated with active energy rays of the above-mentioned illuminance and light intensity to obtain a laminate. After storing the layered body under the conditions of 85° C. and 85% RH (damp heat conditions) for 240 hours, it was taken out under normal temperature and humidity of 23° C. and 50% RH. At this time, it can be confirmed that the degree of whitening of the adhesive layer 11 is small.

The degree of whitening can be quantitatively evaluated by the haze value. Specifically, it can be based on the haze value (%) (measured based on JIS K7136: 2000) after the above-mentioned layered body under damp and heat conditions. The same below is subtracted from the value of the haze value (%) before damp and heat conditions (after damp and heat conditions) The haze value rises) for evaluation. The increase in the haze value after the damp heat condition is preferably less than 5.0 points, and particularly preferably less than 1.0 points. In addition, in the above-mentioned evaluation, it is preferable to utilize a haze value of almost 0% as the above-mentioned alkali-free glass. In addition, the haze value of the adhesive layer after the heat and humidity conditions is preferably 1.0% or less, particularly preferably 0.9% or less, and even more preferably 0.8% or less.

In addition, the total light transmittance (value measured based on JIS K7361-1:1997) of the adhesive layer 11 is preferably 80% or more, particularly preferably 90% or more, and still more preferably 99% or more. If the total light transmittance is 80% or more, the transparency is high and it is suitable for optical applications. In addition, the total light transmittance of the adhesive layer 11 is generally almost unchanged before and after the active energy ray irradiation.

The embodiments described above are described in order to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above-mentioned embodiment also includes all design changes and equivalents belonging to the technical scope of the present invention.

For example, either of the release sheets 12a and 12b of the adhesive sheet 1 may be omitted. In addition, the first hard board 21 may have irregularities other than the printed layer 3 or may not have irregularities. In addition, not only the first hard board 21 but also the second hard board 22 may have irregularities on the adhesive layer 11 side.

[Examples]

Hereinafter, the present invention will be further described in detail through examples and the like, but the scope of the present invention is not limited by these examples and the like.

[Example 1]

1. Preparation of (meth)acrylate copolymer

60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate, and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized to prepare a (meth)acrylate copolymer (A). The molecular weight of the (meth)acrylate copolymer (A) was measured by the method described below, and as a result, the weight average molecular weight was 600,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth)acrylate copolymer (A) obtained in the above step (1) (solid content conversion value; the same hereinafter); as the active energy ray curable component (B), polyethylene glycol Diacrylate (manufactured by Shinnakamura Chemical Co., Ltd., trade name "NK ester A-400") 25 parts by mass; as an isocyanate-based bridging agent (C), trimethylolpropane modified tolylene diisocyanate (Nippon Polyurethane Kogyo Co., Ltd., trade name "CORONATE L") 0.23 parts by mass; as a silane coupling agent, 3-epoxypropoxytrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") 0.2 mass part Parts; as the photopolymerization initiator (D), 0.5 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, trade name "IRUGACURE 184"), mixed, stirred well, and passed through the use of methyl ethyl The ketone was diluted to obtain a coating solution of the adhesive composition having a solid content concentration of 33% by mass.

Here, the combination of the adhesive composition is shown in Table 1. In addition, the details of the abbreviations and the like described in Table 1 are as follows.

[(Meth)acrylate copolymer]

2EHA: 2-ethylhexyl acrylate

BA: n-butyl acrylate

MMA: methyl methacrylate

HEA: 2-hydroxyethyl acrylate

AA: Acrylic

[Active energy ray curable component]

A400: Polyethylene glycol diacrylate (manufactured by Shinnakamura Chemical Co., Ltd., trade name "NK ester A-400")

A9300-1CL: ε-caprolactone modified tris-(2-(meth)acryloyloxyethyl) isocyanate (manufactured by Shinnakamura Chemical Co., Ltd., trade name "A-9300-1CL")

[Bridge Agent]

TDI: Trimethylolpropane modified tolylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "CORONATE L")

Epoxy: 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Corporation, trade name "TETRAD-C")

3. Manufacture of bonding sheet

The obtained coating solution of the adhesive composition was applied to one surface of the polyethylene terephthalate film with a silicone-based release agent for a heavy release release sheet (Lintec Co., Ltd.) The release-treated surface of the company's product, trade name "SP-PET752150") was coated with a knife coater to make the thickness after drying 100 μm, and then heated at 100°C for 4 minutes to form a coating layer. Similarly, the obtained coating solution of the adhesive composition was applied to one surface of a polyethylene terephthalate film with a silicone-based release agent for a light release release sheet (Linde The peeling treatment surface of Kojoki Co., Ltd. (trade name "SP-PET382120") was coated with a knife coater to make the thickness after drying 100 μm, and then heat-treated at 100°C for 4 minutes to form a coating layer.

Next, the above-obtained heavy release release sheet with a coating layer and the light release release sheet with a coating layer obtained above were bonded together so that the coating layers on both sides were in contact with each other. It was aged for 7 days under the conditions, and an adhesive sheet formed of a heavy peeling type release sheet/adhesive layer (thickness: 200 μm)/light peeling type peeling sheet was manufactured. In addition, the thickness of the adhesive layer is a value measured using a constant pressure thickness gauge (manufactured by Techlock Corporation, trade name "PG-02") based on JIS K7130.

[Examples 2~4, Comparative Examples 1~3]

In addition to the ratio of the monomers constituting the (meth)acrylate copolymer (A), the weight average molecular weight of the (meth)acrylate copolymer (A), the type and combination of active energy ray curable components (B) The amount, the type and amount of the bridging agent (C), the amount of the photopolymerization initiator (D), the amount of the silane coupling agent, and the thickness of the adhesive layer were changed according to Table 1, and the same as in Example 1. Perform the same operation to manufacture the adhesive sheet.

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

<Measurement conditions>

‧GPC measuring device: manufactured by TOSOH, HLC-8020

‧GPC column (pass in the following order): made by TOSOH

TSK guard column HXL-H

TSK gel GMHXL(×2)

TSK gel G2000HXL

‧Measuring solvent: Tetrahydrofuran

‧Measuring temperature: 40℃

[Test Example 1] (Measurement of storage modulus)

From the adhesive sheet obtained in the Example or the comparative example, the light peeling type peeling sheet and the heavy peeling type peeling sheet were peeled, and the thickness of an adhesive bond layer was 0.6 mm, and multiple layers were laminated|stacked. From the obtained laminate of adhesive layers, a cylinder (height: 0.6 mm) with a diameter of 8 mm was punched out, and this was used as a sample (sample before ultraviolet irradiation).

With respect to the above-mentioned sample, based on JIS K7244-6, a viscoelasticity measuring device (manufactured by Physica Corporation, MCR300) was used, and the storage modulus (MPa) was measured under the following conditions according to the torsion shear method.

Measurement frequency: 1Hz

Measuring temperature: 23℃, 85℃

In addition, for the same sample as above, by using an ultraviolet irradiation device (manufactured by EYE GRAPHIC, trade name "EYE GRANTAGEECS-401GX"), irradiating ultraviolet rays under the following conditions to cure the adhesive layer to obtain an ultraviolet irradiated product sample. The obtained sample after ultraviolet irradiation was performed in the same manner as the sample before ultraviolet irradiation, and the storage modulus (MPa) was measured.

[Ultraviolet radiation conditions]

‧Light source: high-pressure mercury lamp

‧Light quantity: 1000mJ/cm2

‧Illuminance: 200mW/cm2

In the above measurement results, the ratio of the storage modulus after UV irradiation at 23°C and 85°C to the storage modulus before UV irradiation (storage modulus after UV irradiation/before UV irradiation is calculated) The storage modulus). Table 2 shows these measurement results and calculation results.

[Test Example 2] (Evaluation of Workability)

From the adhesive sheet obtained in the Example or the comparative example, the light-peelable peeling sheet was peeled, and the peeling condition of the light-peelable peeling sheet at this time was evaluated as processability. The evaluation that the light-peelable release sheet was smoothly peeled from the adhesive layer was evaluated as good workability (○), and the evaluation that the adhesive layer was damaged when the light-peelable release sheet was peeled off was evaluated as poor workability (×). The results are shown in Table 2.

[Test Example 3] (Evaluation of resistance to damp and heat whitening)

The adhesive layer of the adhesive sheet obtained in the example or the comparative example was sandwiched between two sheets of alkali-free glass with a thickness of 1.1mm, across the glass on one side, and irradiated with ultraviolet rays under the ultraviolet irradiation conditions of Test Example 1. , Get a laminate. For this laminate, a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., trade name "NDH2000") was used to measure the haze value (%) based on JIS K7136:2000.

Then, the above-mentioned layered body was stored for 240 hours under humid heat conditions of 85°C and 85% RH. After that, it was restored to normal temperature and humidity of 23°C and 50%RH, and the layered body was measured with a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., trade name "NDH2000") based on JIS K7136:2000 ( %). In addition, this haze value is measured within 30 minutes after returning the laminated body to normal temperature and humidity.

Based on the above results, the haze value before the humid heat condition is subtracted from the haze value after the humid heat condition, and the increase in the haze value after the humid heat condition (points) is calculated. If the haze value rises less than 1.0 point after damp heat conditions, it is evaluated as good resistance to damp heat whitening (○), and if the haze value rises greater than 1.0 point less than 5.0 points after damp heat conditions, it is evaluated that the wet heat whitening resistance is within an appropriate value (△) , The evaluation of the haze value rising more than 5.0 points after damp heat condition is poor damp heat whitening resistance (×). The results are shown in Table 2.

[Test Example 4] (Concave-convex compliance and durability test)

(a) Preparation of evaluation samples

On the surface of a glass plate (manufactured by NSG PRECISION, brand name "Corning Glass, Eagle XG", vertical 90mm × horizontal 50mm × thickness 0.5mm), an ultraviolet curable ink (manufactured by Teikoku Ink Corporation, trade name "POS-911 ink") "), screen printing is performed on a frame shape (outer shape: vertical 90 mm × horizontal 50 mm, thickness 5 mm), and the coating thickness is 8 μm and 15 μm. Next, irradiate ultraviolet rays (80W/cm ² , 2 metal halide lamps, lamp height 15cm, belt speed 10m/min~15m/min) to cure the above-mentioned ultraviolet curable ink printed to produce unevenness ( Concave and convex height: 8μm and 15μm) with concavo-convex glass plate.

The adhesive sheet obtained in the example or the comparative example was cut into a shape of 90 mm in the longitudinal direction × 50 mm in the transverse direction, and the lightly peelable release sheet was removed to expose the adhesive layer. Then, using a laminator (manufactured by Fuji, trade name "LPD3214"), the adhesive layer was used to cover the entire frame-like printing, and the adhesive sheet was plastic-sealed on a glass plate with unevenness.

After the above-mentioned plastic packaging, the heavy-peelable release sheet is peeled off, and on the exposed adhesive layer, a glass plate (manufactured by NSG PRECISION, brand name "Corning Glass, Eagle XG", vertical 90mm × horizontal 50mm × thickness 0.5mm ), use the above-mentioned plastic packaging machine to mold and prepare samples for evaluation.

(b) Evaluation of Convex and Convex Compliance (Initial)

The obtained sample for evaluation was pressurized at 0.5 MPa and 50°C for 30 minutes in an autoclave manufactured by Kurihara Manufacturing Co., Ltd. Then, check with the naked eye whether there are bubbles on the adhesive layer (especially due to near the unevenness of the printed layer). As a result, the evaluation of no bubbles at all was rated as ⊚, the evaluation of almost no bubbles was rated as ○, and the evaluation of presence of bubbles was rated ×. (Evaluation of the initial conformability of unevenness). The results are shown in Table 2.

(c) Durability (concave and convex compliance after durability) evaluation

Next, the aforementioned samples for evaluation (1) and (2) were stored for 240 hours under moist heat conditions of 85° C. and 85% RH. After that, visually check whether there are bubbles on the adhesive layer (especially near the unevenness of the printed layer). As a result, the evaluation of no bubbles at all was rated as ⊚, the evaluation of almost no bubbles was rated as ○, and the evaluation of presence of bubbles was rated ×. (Evaluation of durability (adherence to unevenness after durability)). The results are shown in Table 2.

[Test Example 5] (Measurement of total light transmittance)

The adhesive layer of the adhesive sheet obtained in the Example or the comparative example was bonded to glass, and this was used as the sample for measurement. After the background measurement on the glass, the above-mentioned sample for measurement was measured based on JIS K7361-1:1997 using a haze meter (Nippon Denshoku Kogyo Co., Ltd., NDH-2000) to measure the total light transmittance (%) . The results are shown in Table 2.

[Test Example 6] (Evaluation of Water Foam Resistance)

By sputtering, a transparent conductive film made of indium tin oxide (ITO) and a thickness of 125 μm polyethylene terephthalate film (made by OIKE Corporation, ITO film) was prepared on one surface.

The adhesive layer of the adhesive sheet obtained in the examples or comparative examples was made of the transparent conductive film of the above-mentioned ITO film and a polycarbonate plate with a thickness of 1 mm (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "UPIRON‧SHEET MR58"). ") It is sandwiched, the polycarbonate plate is penetrated, and ultraviolet rays are irradiated under the ultraviolet irradiation conditions of Test Example 1 to obtain a laminate.

The resultant layered body was subjected to autoclave sterilization under the conditions of 50°C and 0.5 MPa for 30 minutes, and then allowed to stand for 15 hours. Then, it was stored for 72 hours under durable conditions of 85° C. and 85% RH. After that, visually check whether there are bubbles, floating, or peeling on the adhesive layer. As a result, the evaluation of no air bubbles, floating, or peeling at all was rated as ⊚, the evaluation of almost no air bubbles, floating, or peeling was rated as ○, and the evaluation of generating bubbles, floating, or peeling was rated ×. (Evaluation of blister resistance). The results are shown in Table 2.

It can be seen from Table 2 that the adhesive sheets obtained in the examples are excellent in workability. In addition, the adhesive layer obtained in the examples has excellent concavity and convexity followability before ultraviolet irradiation, and also has excellent moisture and heat whitening resistance, durability, and blistering resistance after ultraviolet irradiation.

[Industrial availability]

The active energy ray-curable adhesive sheet of the present invention is suitable for bonding with, for example, a display module, a protection board with unevenness, and especially a plastic board.

1‧‧‧Active energy ray curable adhesive sheet

11‧‧‧Adhesive layer

12a, 12b‧‧‧Release sheet

Claims (19)

An active energy ray-curable adhesive sheet, which contains an active energy ray-curable adhesive layer and is used for bonding two hard boards to each other, and is characterized in that: at least one of the above-mentioned hard boards , The surface on the side of the adhesive layer has unevenness, the thickness of the adhesive layer is 50 to 400 μm, and the storage modulus of the adhesive layer at 23° C. before the active energy ray is 0.01 to 0.2 MPa, The storage modulus of the adhesive layer at 23°C after irradiated with active energy rays is 0.02 to 0.6 MPa, and the storage modulus at 23°C after the active energy ray is irradiated to the adhesive layer is relative to the adhesive layer The ratio of the storage modulus of the agent layer at 23°C before irradiating the active energy rays is 1.1-10; the two sides of the above-mentioned adhesive layer are sandwiched by two alkali-free glasses with a thickness of 1.1 mm, and the glass on one side will pass through The laminate obtained by irradiating the active energy rays is stored at 85°C and 85%RH for 240 hours, and then the haze value (%) when taken out at 23°C and 50%RH under normal temperature and humidity is subtracted from the above The value of the haze value (%) before the hot and humid conditions, and the increase in the haze value after the hot and humid conditions is less than 5.0 points. An active energy ray-curable adhesive sheet, which contains an active energy ray-curable adhesive layer and is used for bonding two hard boards to each other, and is characterized in that: at least one of the above-mentioned hard boards Contains plastic board, The storage modulus of the adhesive layer at 23°C before active energy rays is 0.01~0.2MPa, and the storage modulus of the adhesive layer at 23°C after active energy rays is 0.02~0.6MPa. The ratio of the storage modulus of the adhesive layer at 23°C after the active energy ray is irradiated to the storage modulus at 23°C before the active energy ray is irradiated to the adhesive layer is 1.1-10; The two sides of the layer are sandwiched between two sheets of alkali-free glass with a thickness of 1.1mm. The laminate obtained by irradiating active energy rays through the glass on one side is stored at 85°C and 85%RH for 240 hours. The haze value (%) when taken out under normal temperature and humidity of 23°C and 50%RH minus the value of the haze value (%) before the above damp and heat conditions, the increase in the haze value after damp and heat conditions is less than 5.0 points . An active energy ray-curable adhesive sheet, which contains an active energy ray-curable adhesive layer and is used for bonding two hard boards to each other, and is characterized in that: at least one of the above-mentioned hard boards , There are unevenness on the surface of the adhesive layer side, the thickness of the adhesive layer is 50~400μm, and the storage modulus at 85°C after the adhesive layer is irradiated with active energy rays is 0.02~0.2MPa , The ratio of the storage modulus at 85°C after irradiating the adhesive layer with active energy rays to the storage modulus at 85°C before irradiating the adhesive layer with active energy rays is 1.1-10; The above-mentioned adhesive layer is sandwiched between two non-alkali glasses with a thickness of 1.1mm on both sides, and the laminate obtained by irradiating active energy rays through the glass on one side is stored at 85°C and 85%RH under humid and hot conditions. 240 After hours, the haze value (%) is subtracted from the haze value (%) when taken out under normal temperature and humidity at 23°C and 50%RH, and the haze value rises after the heat and humidity conditions. Less than 5.0 points. An active energy ray-curable adhesive sheet, which contains an active energy ray-curable adhesive layer and is used for bonding two hard boards to each other, and is characterized in that: at least one of the above-mentioned hard boards Including a plastic board, the storage modulus at 85°C after irradiating the adhesive layer with active energy rays is 0.02~0.2MPa, and the storage modulus at 85°C after irradiating the adhesive layer with active energy rays is relatively The ratio of the storage modulus at 85°C before the active energy ray is irradiated to the adhesive layer is 1.1 to 10; the two sides of the adhesive layer are sandwiched by two alkali-free glasses with a thickness of 1.1 mm. The layered product obtained by irradiating active energy rays through the glass on one side was stored under humid and hot conditions of 85°C and 85%RH for 240 hours, and then taken out from the haze value when it was taken out at 23°C and 50%RH under normal temperature and humidity ( %) Subtract the value of the haze value (%) before the hot and humid conditions, and the increase in the haze value after the hot and humid conditions is less than 5.0 points. According to the active energy ray curable adhesive sheet according to item 3 or 4 of the scope of patent application, the storage modulus of the adhesive layer at 23° C. before the active energy ray is irradiated is 0.01 to 0.2 MPa. According to the active energy ray curable adhesive sheet according to item 3 or 4 of the scope of patent application, the storage modulus of the adhesive layer at 23° C. after being irradiated with active energy rays is 0.02-2 MPa. The active energy ray curable adhesive sheet according to any one of items 1 to 4 in the scope of patent application, wherein the storage modulus at 85°C before the active energy ray is irradiated to the adhesive layer is 0.01 to 0.1 MPa . According to the active energy ray curable adhesive sheet according to item 1 or 2 of the scope of patent application, the storage modulus at 85° C. after the active energy ray is irradiated to the adhesive layer is 0.02 to 0.5 MPa. According to the active energy ray curable adhesive sheet according to item 2 or 4 of the scope of patent application, the thickness of the adhesive layer is 50 to 400 μm. The active energy ray-curable adhesive sheet according to any one of items 1 to 4 of the scope of patent application, wherein the adhesive sheet includes two release sheets, and the adhesive layer is separated from the two release sheets The face-to-face contact is sandwiched by the above-mentioned release sheet. A laminate, characterized in that it includes two hard plates and an adhesive layer sandwiched between the two hard plates, at least one of the hard plates has irregularities on a surface on the adhesive layer side, the The adhesive layer is formed by curing the adhesive layer of the active energy ray-curable adhesive sheet described in item 1 or 3 of the scope of the patent application after being irradiated with active energy rays. A laminated body, characterized in that it is provided with two hard boards and an adhesive layer sandwiched between the two hard boards, at least one of the hard boards includes a plastic board, and the adhesive layer is the second in the scope of patent application. Or the adhesive layer of the active energy ray curable adhesive sheet described in item 4 is cured by active energy ray irradiation Become. The laminate according to claim 12, wherein at least one of the hard plates has unevenness on the surface on the adhesive layer side. The laminated body according to the 11th or 13th item of the scope of patent application, wherein the above-mentioned unevenness is an unevenness due to the presence or absence of a printing layer. The laminate according to item 11 or 12 of the scope of patent application, wherein at least one of the above-mentioned hard plates includes a polarizing plate. The laminate according to item 11 of the scope of patent application, wherein at least one of the above-mentioned hard boards includes a plastic board. According to the laminated body described in item 12 or 16 of the scope of patent application, the thickness of the plastic plate is 0.4 mm or more. According to the laminate described in item 11 of the scope of patent application, the hard board does not include a plastic board. The laminate according to item 11 or 12 of the scope of patent application, wherein one of the two hard boards is a display module or a part thereof, and the other of the two hard boards is on the side of the adhesive layer , A protective board with frame-shaped bumps.

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