TW201704397A - Adhesive sheet and display body for filling the gap between the protective panel and the display module to reduce light reflection and have excellent level difference traceability - Google Patents

Abstract

The present invention provides an adhesive sheet and a display body which is excellent in level difference traceability and excellent reprocessability even under high temperature and high humidity conditions. The adhesive sheet (1) of the present invention has an adhesive layer (11) for bonding one having level difference of a plurality of display body members on at least one side of the bonded surfaces with another display body member, wherein the adhesive layer (11) is composed of an adhesive agent obtained by crosslinking an adhesive composition comprising (meth) acrylate copolymer (A), a crosslinking agent (B) and a silicone oil (C), said (meth) acrylate copolymer (A) contains 7 to 40% by mass of a hydroxyl group-containing monomer or 6 to 20% by mass of a carboxyl group-containing monomer as a monomer unit constituting the copolymer. The adhesive fraction of the adhesive agent is 40 to 90%, and the adhesion strength of the adhesive sheet for the alkaleness glass is 15~26N/25mm.

Description

Adhesive sheet and display body

The present invention relates to an adhesive sheet for bonding a display member constituting member and a display body obtained by using an adhesive layer of the adhesive sheet.

In recent years, various mobile electronic devices such as mobile phones, smart phones, and tablet computers include display bodies using display body modules having liquid crystal elements, light emitting diodes (LED elements), organic electroluminescence (organic EL) elements, and the like. (display: display).

In such a display, a protective panel is usually provided on the surface side of the display body module. A gap is provided between the protection panel and the display body module to prevent the protection panel that is deformed when the protection panel is deformed by an external force to collide with the display body module.

However, if there is a void, that is, an air layer as described above, the difference in refractive index between the protective panel and the air layer and the reflection loss of light caused by the difference in refractive index between the air layer and the display module increase, and there is a display. The problem of degraded picture quality.

Therefore, it has been proposed to improve the image quality of the display by filling the gap between the protective panel and the display body module with the adhesive layer. However, on the display module side of the protective panel, the border-shaped printed layer sometimes exists as a step. If the adhesive layer does not follow the step, the adhesive layer floats in the vicinity of the step, thereby causing a reflection loss of light. Therefore, step adhesion follow-up is required for the above adhesive layer.

In order to solve the above problem, in Patent Document 1, as an adhesive layer filling a gap between a protective panel and a display body module, it is revealed that the shear storage elastic modulus (G') at 25 ° C and 1 Hz is 1.0 ×. An adhesive layer of 10 ⁵ Pa or less and a gel fraction of 40% or more.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2010-97070

In Patent Document 1, it is intended to improve the step followability by reducing the storage elastic modulus at the normal temperature in the adhesive layer. However, if the storage elastic modulus at the normal temperature is lowered as described above, the storage elastic modulus at a high temperature is excessively lowered, which causes a problem under endurance conditions. For example, when a high-temperature and high-humidity condition is applied, a problem such as generation of bubbles or the like in the vicinity of the step occurs.

Further, it is often the case that the protective panel and the display body module are bonded together with the adhesive sheet of the adhesive layer as described above. When the bonding is performed, the bonding position sometimes deviates. In particular, as described above, it is more difficult to bond the hard materials (hard bodies) to each other by the adhesive sheet than to bond the films or the film to the hard body, and the yield at the time of bonding is likely to be lowered.

Here, since the display body module is expensive, when the problem of the misalignment as described above occurs, if the display module side can be reused at least, the production cost can be compressed. Therefore, it is expected that the adhesive sheet as described above can be reworked by peeling the two hard bodies bonded by the adhesive sheet so that at least the display body module can be reused.

The present invention has been made in view of such an actual situation, and an object of the invention is to provide an adhesive sheet and a display body which are excellent in step followability even under high temperature and high humidity conditions and which are excellent in reworkability.

In order to achieve the above object, a first aspect of the present invention provides an adhesive sheet having an adhesive layer for forming a display member having a step on at least a side of a side of a fitting body and a display member of another display body. The adhesive member is characterized in that the adhesive layer is composed of an adhesive obtained by crosslinking an adhesive composition, and the adhesive composition contains a (meth) acrylate copolymer (A) and a crosslinking agent ( B) and eucalyptus oil (C), the (meth) acrylate copolymer (A) contains 7 to 40% by mass of a hydroxyl group-containing monomer or 6 to 20% by mass of a carboxyl group-containing monomer as a copolymer. In the monomer unit, the gel fraction of the adhesive is 40 to 90%, and the adhesion of the adhesive sheet to the alkali-free glass is 15 to 26 N/25 mm (Invention 1).

When the adhesive sheet of the invention (Invention 1) is attached to the display member constituting member having a step, the adhesive layer easily follows the step, and it is possible to suppress occurrence of a gap, a floating, or the like in the vicinity of the step. Further, even when it is placed under high temperature and high humidity conditions in this state, generation of bubbles, floating, peeling, and the like in the vicinity of the step can be suppressed. Further, the pressure-sensitive adhesive sheet can be easily peeled off from the display body constituent member even after being temporarily attached to the display body constituent member, and is excellent in reworkability.

In the above invention (Invention 1), the content of the eucalyptus oil (C) in the adhesive composition is preferably 0.01 to 1.8 parts by mass based on 100 parts by mass of the (meth) acrylate copolymer (A). 2).

In the above invention (Inventions 1 and 2), the aforementioned eucalyptus oil (C) has an official The energy base is preferred (Invention 3).

In the above invention (Inventions 1 to 3), it is preferred that the eucalyptus oil (C) has a viscosity at 25 ° C of 5 to 100 mm ² /sec (Invention 4).

In the above invention (Inventions 1 to 4), the (meth) acrylate copolymer (A) may contain an alicyclic structure-containing monomer and a nitrogen atom-containing monomer as a monomer unit constituting the copolymer (Invention 5) ).

In the above invention (Inventions 1 to 5), it is preferred that the pressure-sensitive adhesive layer has a haze value of 1.0% or less (Invention 6).

In the above invention (Inventions 1 to 6), the pressure-sensitive adhesive sheet includes two release sheets, and the pressure-sensitive adhesive layer is preferably sandwiched between the release sheets in contact with the release surfaces of the two release sheets (Invention 7). .

Secondly, the present invention provides a display body comprising: a display member having a step at least on a side of the side of the bonding; a display member constituting member; and a display member constituting member and the aforementioned An adhesive layer which is formed by bonding the body constituent members to each other, wherein the adhesive layer is an adhesive layer of the adhesive sheet according to any one of Inventions 1 to 7 (Invention 8).

The adhesive sheet and the display of the present invention are excellent in step followability even under high temperature and high humidity conditions, and are excellent in reworkability.

1‧‧‧Adhesive film

11‧‧‧Adhesive layer

12a, 12b‧‧‧ peeling film

2‧‧‧Display

21‧‧‧1st display body constituent member

22‧‧‧2nd display body constituent member

3‧‧‧Printing layer

Fig. 1 is a cross-sectional view showing an adhesive sheet according to an embodiment of the present invention.

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

Hereinafter, embodiments of the present invention will be described.

[adhesive sheet]

The pressure-sensitive adhesive sheet according to the present embodiment has an adhesive layer for bonding one of the display member members having a step on at least the side of the bonding surface to the other display member constituting member. The specific configuration of the adhesive sheet, the display body, and the display body constituent member will be described later.

The adhesive layer of the adhesive sheet of the present embodiment is an adhesive composition containing (meth) acrylate copolymer (A), a crosslinking agent (B), and eucalyptus oil (C) (hereinafter, sometimes referred to as "adhesion" The composition P"") is composed of an adhesive formed by crosslinking. Further, the (meth) acrylate copolymer (A) contains 7 to 40% by mass of a hydroxyl group-containing monomer or 6 to 20% by mass of a carboxyl group-containing monomer as a monomer unit constituting the copolymer. Further, the adhesive has a gel fraction of 40 to 90%, and the adhesive sheet of the present embodiment has an adhesion to alkali-free glass of 15 to 26 N/25 mm. In the present specification, (meth)acrylic means both acrylic acid and methacrylic acid. Other similar terms are also the same. Moreover, the concept of "copolymer" is also considered to be included in "polymer".

When the adhesive sheet satisfying the above requirements is attached to the display member constituting member having a step, the adhesive layer easily follows the step, and it is possible to suppress occurrence of a gap, a floating, or the like in the vicinity of the step. Further, even when it is left under high temperature and high humidity conditions in this state, for example, at 85 ° C and 85% RH for 72 hours, generation of bubbles, floating, peeling, and the like in the vicinity of the step can be suppressed. As described above, the adhesive sheet of the present embodiment is excellent in step followability, and is particularly excellent in step followability even under high temperature and high humidity conditions. Further, the adhesive sheet of the present embodiment can be easily formed from the display body member even after being temporarily attached to the display body constituent member. Stripped and excellent in reworkability.

(1) (meth) acrylate copolymer (A)

The (meth) acrylate copolymer (A) contains 7 to 40% by mass of a hydroxyl group-containing monomer or 6 to 20% by mass of a carboxyl group-containing monomer as a monomer unit constituting the polymer. By reacting the (meth) acrylate copolymer (A) with a hydroxyl group-containing monomer or a carboxyl group-containing monomer, a hydroxyl group derived from a hydroxyl group-containing monomer or a carboxyl group derived from a carboxyl group-containing monomer, and a crosslinking agent (B) By forming a crosslinked structure (three-dimensional network structure), an adhesive having a desired cohesive force can be obtained. In particular, as described above, the (meth) acrylate copolymer (A) contains a hydroxyl group-containing monomer or a carboxyl group-containing monomer in a large amount, and the obtained adhesive layer becomes a step difference under high temperature and high humidity conditions. It is excellent in both sex and is also excellent in moisture and heat whitening resistance. In addition, the wet heat whitening refers to a phenomenon in which the display layer containing the adhesive layer is whitened after returning to normal temperature and humidity after being subjected to high temperature and high humidity conditions.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-(meth)acrylate. A hydroxyalkyl (meth)acrylate such as hydroxybutyl ester, 3-hydroxybutyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate. Among them, from the viewpoint of the reactivity of the hydroxyl group in the obtained (meth) acrylate copolymer (A) with the crosslinking agent (B) and the copolymerizability with other monomers, 2-hydroxyl (meth) acrylate Ethyl ester or 4-hydroxybutyl (meth)acrylate is preferred. These may be used alone or in combination of two or more.

When the (meth) acrylate copolymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, as described above, the content thereof is 7 to 40% by mass, preferably 12 to 35% by mass. 16~30% by mass is especially good. When included When the content of the hydroxy monomer is less than 7% by mass, sufficient wet heat whitening resistance cannot be obtained. In addition, when the content of the hydroxyl group-containing monomer exceeds 40% by mass, the degree of crosslinking becomes too large, and the obtained adhesive becomes hard, and the step followability deteriorates or an appropriate adhesiveness cannot be obtained.

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

When the (meth) acrylate copolymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, as described above, the content thereof is 6 to 20% by mass, preferably 8 to 18% by mass. 10~15% by mass is especially good. When the content of the carboxyl group-containing monomer is less than 6% by mass, sufficient wet heat whitening resistance cannot be obtained. In addition, when the content of the carboxyl group-containing monomer exceeds 20% by mass, the degree of crosslinking becomes excessively large, and the obtained adhesive becomes hard, and the step followability deteriorates. Also, it is not possible to obtain proper adhesion.

The (meth)acrylate copolymer (A) having an alkyl group having 1 to 20 carbon atoms of (meth)acrylic acid as a monomer unit constituting the polymer can exhibit better adhesion. . From such a viewpoint, the (meth) acrylate copolymer (A) contains 40 to 93% by mass of an alkyl group having 1 to 20 carbon atoms as an alkyl group constituting the polymer. Body units are preferred. Further, when the (meth) acrylate copolymer (A) contains a hydroxyl group-containing monomer as a constituent unit, the alkyl (meth) acrylate having a carbon number of from 1 to 20 in an amount of from 50 to 80% by mass of the alkyl group is used. More preferably, it contains 55~70% by mass, especially good. On the other hand, when the (meth) acrylate copolymer contains a carboxyl group-containing monomer as a constituent unit, the alkyl (meth) acrylate having a carbon number of from 1 to 20 in an alkyl group of 60 to 92% by mass is more Preferably, it is preferably 75 to 90% by mass. When the (meth)acrylic acid alkyl ester is contained in an amount of 40% by mass or more, the (meth) acrylate copolymer (A) can exhibit desired adhesiveness. In addition, by setting the alkyl (meth)acrylate to 93% by mass or less, the other monomer component can be introduced into the (meth)acrylate copolymer (A) in a desired amount. Further, the alkyl group in the alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group means a linear or branched alkyl group.

Examples of the (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate. N-butyl acrylate, n-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, (meth)acrylic acid N-decyl ester, n-dodecyl (meth)acrylate, tetradecyl (meth)acrylate, cetyl (meth)acrylate, octadecyl (meth)acrylate, etc. Among them, a (meth) acrylate having an alkyl group and having 1 to 8 carbon atoms is preferred from the viewpoint of further improving the adhesion.

It is also preferred that the (meth) acrylate copolymer (A) contains an alicyclic structure-containing monomer and a nitrogen atom-containing monomer as the monomer unit constituting the copolymer. Since the alicyclic structure-containing monomer has a large volume, the gap between the polymers can be increased by being present in the polymer, and the obtained adhesive can be excellent in flexibility. Thereby, the adhesive becomes more excellent in the step followability. And, by using a nitrogen atom-containing monomer as a constituent unit in the polymer, the adhesive is applied By imparting a predetermined polarity, it is also excellent in affinity to a adherend having a certain degree of polarity such as a transparent conductive film or glass.

In the case where the (meth) acrylate copolymer (A) contains a hydroxyl group-containing monomer as a constituent unit, it has a ratio of a carboxyl group-containing monomer as a constituent unit in the copolymer (A). The glass transition temperature (Tg) of the obtained copolymer (A) tends to decrease. Therefore, the cohesive force of the adhesive which forms a crosslinked structure by a hydroxyl group tends to be insufficient as compared with the adhesive which forms a crosslinked structure by a carboxyl group, and it tends to foam or peel easily when it is exposed to high temperature and high humidity conditions for a long period of time. That is, there is a case where the step followability under high temperature and high humidity conditions is insufficient.

On the other hand, when the (meth) acrylate copolymer (A) contains an alicyclic structure-containing monomer and a nitrogen atom-containing monomer as a constituent unit, the adhesive having a crosslinked structure is formed as a constituent unit. The glass transition temperature (Tg) of the copolymer (A) can be increased to a desired range to increase the cohesive force of the obtained adhesive.

In other words, it is estimated that the above-described step followability is combined with the properties of the above affinity by including the alicyclic structure-containing monomer and the nitrogen-containing monomer as a constituent unit in the (meth) acrylate copolymer (A). Furthermore, the effect of improving the cohesive force in the adhesive which forms a crosslinked structure from a hydroxyl group is also combined, and the obtained adhesive becomes more excellent in the step followability under high temperature and high humidity conditions. Therefore, the (meth) acrylate copolymer (A) contains both an alicyclic structure-containing monomer and a nitrogen atom-containing monomer as a monomer unit constituting the copolymer, and the step of the obtained adhesive is followed. Very excellent, and transparent conductive film, especially made of tin-doped indium oxide (ITO), glass, and plastic, especially polycarbon Plastics such as acid esters and polymethyl methacrylate exert strong adhesion.

The carbon ring of the alicyclic structure in the alicyclic structure-containing monomer may be a saturated structure or a part having an unsaturated bond. Further, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic ring or a tricyclic ring. The alicyclic structure is a polycyclic alicyclic structure from the viewpoint of appropriately setting the distance between the obtained (meth) acrylate copolymers (A) and imparting stress relaxation property to the adhesive. Ring structure) is preferred. Further, in consideration of the compatibility of the (meth) acrylate copolymer (A) with other components, the polycyclic structure is preferably bicyclic to tetracyclic. Further, in the same manner as described above, the carbon number of the alicyclic structure (referred to as the carbon number of the portion forming the ring, when a plurality of rings are independently present, refers to the total carbon number thereof from the viewpoint of imparting stress relaxation property. It is usually preferably 5 or more, and more preferably 7 or more. On the other hand, the upper limit of the carbon number of the alicyclic structure is not particularly limited, and from the viewpoint of compatibility, 15 or less is preferable, and 10 or less is particularly preferable.

Examples of the alicyclic structure include a cyclohexyl skeleton, a dicyclopentadiene skeleton, an adamantane skeleton, an isobornyl skeleton, a cycloalkane skeleton (a cycloheptane skeleton, a cyclooctane skeleton, a cyclodecane skeleton, and the like). a cyclodecane skeleton, a cycloundecyl skeleton, a cyclododecane skeleton, etc.), a cyclic olefin skeleton (a cycloheptene skeleton, a cyclooctene skeleton, etc.), a norbornene skeleton, a norbornadiene skeleton, a cubane skeleton, Among the blue-alkane skeleton, the alkane skeleton, and the spiro ring skeleton, among them, a dicyclopentadiene skeleton (carbon number of alicyclic structure: 10) and an adamantane skeleton (alicyclic type) exhibiting more excellent durability are exhibited. The carbon number of the structure: 10) or the isobornyl skeleton (carbon number of the alicyclic structure: 7) is preferred, and those containing an isobornyl skeleton are particularly preferred.

As the above-mentioned alicyclic structure-containing monomer, it contains the above skeleton (A) The acrylate monomer is preferred, and specific examples thereof include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, and (meth)acrylic acid. Isobornyl ester, dicyclopentanyl (meth)acrylate, dicyclopentyloxyethyl (meth)acrylate, etc., among which dicyclopentyl (meth)acrylate exhibits more excellent durability, (methyl) Adamantyl acrylate or isobornyl (meth)acrylate is preferred, and isobornyl (meth)acrylate is particularly preferred. These may be used alone or in combination of two or more.

In the (meth) acrylate copolymer (A), the monomer unit constituting the polymer preferably contains from 1 to 40% by mass of the alicyclic structure-containing monomer, and particularly preferably from 2 to 25% by mass. It is further preferably contained in an amount of 4 to 15% by mass. When the content of the alicyclic structure-containing monomer is within the above range, the obtained adhesive can sufficiently exhibit excellent step followability and excellent adhesion to the transparent conductive film and glass and plastic (especially for the transparent conductive film). Excellent adhesion).

Examples of the nitrogen atom-containing monomer include a monomer having an amine group, a monomer having a guanamine group, and a monomer having a nitrogen-containing hetero ring. Among them, a monomer having a nitrogen-containing hetero ring is preferred.

Examples of the monomer having a nitrogen-containing hetero ring include N-(methyl)propenylmorpholine, N-vinyl-2-pyrrolidone, N-(methyl)propenylpyrrolidone, and N-(A). Acrylhydrazine piperidine, N-(methyl)propenylpyridylpyridinium, N-(methyl)propenyl aziridine, aziridine ethyl (meth)acrylate, 2-vinylpyridine , 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylimine, etc., among which N-(A) exhibits more excellent adhesion. The acryloyl morpholine is preferred, and the N-propenyl morpholine is particularly preferred.

Further, as the nitrogen atom-containing monomer other than the monomer having a nitrogen-containing hetero ring, for example, (meth) acrylamide, N-methyl (meth) acrylamide, or N-methylol ( Methyl) acrylamide, N-tert-butyl (meth) acrylamide, N,N-dimethyl(meth) acrylamide, N,N-ethyl(meth) acrylamide, N , N-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-phenyl (meth) acrylamide, dimethylaminopropyl (Meth) acrylamide, N-vinyl caprolactam, monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethyl (meth)acrylate Aminopropyl propyl ester, monoethylaminopropyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and the like.

The above nitrogen atom-containing monomers may be used alone or in combination of two or more.

In the (meth) acrylate copolymer (A), the monomer unit constituting the polymer preferably contains 1 to 40% by mass of a nitrogen atom-containing monomer, more preferably 2 to 25% by mass, and particularly preferably 4 ~15% by mass is further preferred. When the content of the nitrogen atom-containing monomer is within the above range, the obtained adhesive can sufficiently exert excellent adhesion to the transparent conductive film and glass and plastic (especially excellent adhesion to glass and plastic).

In the (meth) acrylate copolymer (A), the monomer unit constituting the polymer preferably contains 2 to 43% by mass of the alicyclic structure-containing monomer and the nitrogen atom-containing monomer, and preferably contains 4 It is particularly preferable that it is ~37% by mass, and further preferably 8 to 30% by mass.

The (meth) acrylate copolymer (A) may contain other monomers as a monomer unit constituting the polymer, as needed. As other monomers, In order not to impede the action of the hydroxyl group-containing monomer or the carboxyl group-containing monomer, a monomer having no reactive functional group is preferred. Examples of such other monomers include (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, ethyl acetate and benzene. Ethylene and the like. These may be used alone or in combination of two or more.

The polymerization form 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 preferably from 200,000 to 900,000, particularly preferably from 300,000 to 700,000, and further preferably from 400,000 to 600,000. Further, the weight average molecular weight in the present specification is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

When the weight average molecular weight of the (meth) acrylate copolymer (A) is in a relatively low range as described above, an adhesive having more excellent step followability can be obtained. When the weight average molecular weight of the (meth) acrylate copolymer (A) exceeds 900,000, the step-following property may be inferior. On the other hand, when the weight average molecular weight of the (meth) acrylate copolymer (A) is 200,000 or more, the adhesive is excellent in durability.

Further, in the adhesive composition P, the (meth) acrylate copolymer (A) may be used alone or in combination of two or more.

(2) Crosslinking agent (B)

When the adhesive composition P containing the crosslinking agent (B) is heated, the crosslinking agent (B) crosslinks the (meth) acrylate copolymer (A) to form a three-dimensional network structure. Thereby, the cohesive force of the obtained adhesive is improved, and it is excellent in the followability of the step even under the conditions of high temperature and high humidity.

The crosslinking agent (B) may be reacted with a reactive functional group (hydroxyl group or carboxyl group) of the (meth) acrylate copolymer (A), and examples thereof include an isocyanate crosslinking agent. , epoxy crosslinking agent, amine crosslinking agent, melamine crosslinking agent, aziridine crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal An alkoxide crosslinking agent, a metal chelate crosslinking agent, a metal salt crosslinking agent, an ammonium salt crosslinking agent, and the like. In the above, when the reactive functional group of the (meth) acrylate copolymer (A) is a hydroxyl group, an isocyanate crosslinking agent excellent in reactivity with a hydroxyl group is preferably used, and (meth)acrylic acid is preferred. When the reactive functional group of the ester copolymer (A) is a carboxyl group, an epoxy-based crosslinking agent excellent in reactivity with a carboxyl group is preferably used. Further, the crosslinking agent (B) may be used alone or in combination of two or more.

The isocyanate crosslinking agent is a compound containing at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate and benzodimethyl diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; and isophorone diisocyanate. And alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate and the like, and the biuret, isocyanurate, and ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and hydrazine Sesame oil or the like is used as an adduct with a reactant containing a low molecular weight active hydrogen compound. Among them, trimethylolpropane-modified aromatic polyisocyanate is preferred from the viewpoint of reactivity with a hydroxyl group, trimethylolpropane-modified toluene diisocyanate and trimethylolpropane-modified phthaldimethyl group. Diisocyanates are especially preferred.

Examples of the epoxy-based crosslinking agent include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane and N,N,N',N'-tetraglycidyl group. - M-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidylamine, and the like. Among them, from the viewpoint of reactivity with a carboxyl group, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane or N,N,N',N'-tetraglycidyl group - Meta-xylylenediamine is preferred.

The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.001 to 2 parts by mass based on 100 parts by mass of the (meth) acrylate copolymer (A), and particularly preferably 0.01 to 1 part by mass, 0.02. ~0.3 parts by mass is further preferred. When the content of the crosslinking agent (B) is 0.001 part by mass or more, the obtained adhesive has excellent step followability under high temperature and high humidity conditions. When the content of the crosslinking agent (B) is 2 parts by mass or less, the degree of crosslinking becomes appropriate, and the step followability of the obtained adhesive can be satisfactorily ensured.

(3) Emu oil (C)

An adhesive obtained from an adhesive composition P containing eucalyptus oil (C) by a combination of eucalyptus oil (C) and a crosslinked structure based on the aforementioned (meth) acrylate copolymer (A) and a crosslinking agent (B) It is excellent in step followability and reworkability under high temperature and high humidity conditions.

Emu oil (C) is an oily compound which is fluid at room temperature, that is, a linear organopolyoxane. The eucalyptus oil (C) used in the present embodiment may be any of unmodified eucalyptus oil and modified eucalyptus oil, but modified eucalyptus oil from the viewpoint of compatibility with the (meth) acrylate copolymer (A) It is better.

Examples of the modified eucalyptus oil include those in which a functional group is introduced into a side chain of an organic polyoxyalkylene oxide (side chain type), and a functional group is introduced at both ends of an organic polyoxyalkylene oxide (both end type). Any of the two ends of the organic polyoxane One having a functional group introduced therein (single-terminal type), a side chain having an organic polyoxyalkylene, and a functional group introduced at both ends (both side chain type) may be used. Among these, a both end type and a single end type are preferable.

Examples of the functional group include an amine group, an epoxy group, a (meth)acryl fluorenyl group, a carboxyl group, a decyl group, a polyether group, an alkyl group, a higher fatty acid ester, fluorine, a phenyl group, a benzyl group, and the like. One or two or more of these may be introduced into the organopolyoxane. Among the above, an amine group, an epoxy group, and a methacryl group are particularly preferable from the viewpoint of compatibility with the (meth) acrylate copolymer (A). In particular, when the (meth) acrylate copolymer (A) contains a hydroxyl group, the functional group is preferably a methacryl oxime group, and the other is preferably a more excellent compatibility. On the other hand, when the (meth) acrylate copolymer (A) contains a carboxyl group, the above functional group is preferably an amine group.

In addition, from the viewpoint of the compatibility of the (meth) acrylate copolymer (A) and the eucalyptus oil (C), the introduction amount of the functional group in the eucalyptus oil (C) is 100 to 10,000 g/mol. Preferably, it is preferably 200 to 8,000 g/mol, and particularly preferably 300 to 6,000 g/mol.

Silicone oil (C) under the viscosity at 25 deg.] C to 5 ~ 100mm ² / sec is preferred, 8 ~ 85mm ² / s is particularly good, 10 ~ 70mm ² / s is further preferable. Since the viscosity of the eucalyptus oil (C) is in the above range, the eucalyptus oil (C) and the (meth) acrylate copolymer (A) are not completely phase-separated, and it is suitable to locally exist in the vicinity of the surface of the formed adhesive layer. The compatibility of the eucalyptus oil (C) to the adherend side can be prevented by moderately entanglement with the (meth) acrylate copolymer (A).

The content of the eucalyptus oil (C) in the adhesive composition P is preferably 0.01 to 1.8 parts by mass, more preferably 0.05 to 1.4 parts by mass, and 0.1 to 0.8 parts by mass based on 100 parts by mass of the (meth) acrylate copolymer (A). The mass fraction is further preferred. When the content of the eucalyptus oil (C) is 0.01 parts by mass or more, the step-followability and the reworkability under the high-temperature and high-humidity conditions based on the eucalyptus oil (C) are further excellent. In addition, when the content of the eucalyptus oil (C) is 1.8 parts by mass or less, the adhesive force for optical use can be satisfactorily exhibited, and the step followability, particularly the step-followability under high temperature and high humidity conditions, is further excellent.

(4) decane coupling agent (D)

The adhesive composition P further preferably contains a decane coupling agent (D). Thereby, if a glass member exists in a to-be-adhered body, the adhesiveness of the obtained adhesive agent and this glass member improves. Moreover, even if the adherend is a plastic plate, the adhesion between the obtained adhesive and the plastic plate is improved. Thereby, the obtained adhesive becomes more excellent in the step followability under high temperature and high humidity conditions.

The decane coupling agent (D) is an organic ruthenium compound having at least one alkoxyfluorenyl group in the molecule, and is compatible with the (meth) acrylate copolymer (A) and has light transmittance. good.

Examples of the decane coupling agent (D) include a polymerizable unsaturated group such as vinyltrimethoxydecane, vinyltriethoxydecane, or methacryloxypropyltrimethoxydecane. Anthracene compound, 3-mercaptopropyl group having an epoxy group structure, such as an anthracene compound, 3-glycidoxypropyltrimethoxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane A fluorenyl-containing hydrazine compound such as trimethoxy decane, 3-mercaptopropyltriethoxy decane, 3-mercaptopropyldimethoxymethyl decane, 3-aminopropyltrimethoxydecane, N-(2) -amino group An amine group-containing oxime compound such as ethyl)-3-aminopropyltrimethoxydecane or N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane, 3-chloro Propyltrimethoxydecane, 3-isocyanatepropyltriethoxydecane, or at least one of these with methyltriethoxydecane, ethyltriethoxydecane, methyltrimethoxydecane, ethyl A condensate of an alkyl group-containing quinone compound such as trimethoxy decane or the like. These may be used alone or in combination of two or more.

The content of the decane coupling agent (D) in the adhesive composition P is preferably 0.01 to 1 part by mass based on 100 parts by mass of the (meth) acrylate copolymer (A), and particularly preferably 0.05 to 0.5 part by mass, 0.1. ~0.3 parts by mass is further preferred.

(5) Active energy ray hardening component (E)

The adhesive composition P may further contain an active energy ray hardening component (E). The adhesive composition P containing the active energy ray-curable component (E) is more excellent in step followability before curing, and is more excellent in reworkability as an adhesive after curing.

The active energy ray-curable component (E) is not particularly limited as long as it does not interfere with the step followability and reworkability and is hardened by irradiation with active energy rays, and may be a monomer, an oligomer or Any of the polymers may also be a mixture of these. Among them, a polyfunctional acrylate monomer having a molecular weight of less than 1,000 which is excellent in compatibility with the (meth) acrylate copolymer (A) or the like can be preferably used.

Examples of the polyfunctional acrylate monomer having a molecular weight of less than 1,000 include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and neopenta-2. Alcohol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, Hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentyl ester di(meth)acrylate, caprolactone modified dicyclopentyl di(meth)acrylate, ethylene oxide modification Phosphate di(meth)acrylate, bis(acryloxyethyl)isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, 2-functional type such as 9,9-bis[4-(2-propenyloxyethoxy)phenyl]indole; trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate , propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, tris(propylene oxyoxyethyl) a trifunctional type such as isocyanurate or ε-caprolactone modified tris-(2-(methyl) propylene oxyethyl) isocyanurate; diglycerin tetra(meth) acrylate, a tetrafunctional type such as pentaerythritol tetra(meth)acrylate; a 5-functional type such as propionic acid-modified dipentaerythritol penta (meth) acrylate; dipentaerythritol hexa(meth) acrylate; and caprolactone-modified dipentaerythritol hexa Methyl acrylate Such as 6-functional type and the like. Among the above, ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate is preferred from the viewpoint of the step followability. These may be used alone or in combination of two or more.

As the active energy ray-curable component (E), an active energy ray-curable acrylate-based oligomer can also be used. The acrylate-based oligomer is preferably a weight average molecular weight of 50,000 or less. Examples of such an acrylate-based oligomer include a polyester acrylate type, an epoxy acrylate type, a urethane acrylate type, a polyether acrylate type, and a polybutadiene acrylate type. Anthrone acrylates and the like.

The weight average molecular weight of the above acrylate-based oligomer is 50,000 or less is preferred, 500 to 50,000 is particularly preferred, and 3,000 to 40,000 is further preferred. These acrylate-based oligomers may be used alone or in combination of two or more.

Further, as the active energy ray-curable component (E), an addition acrylate-based polymer having a group having a (meth)acryl fluorenyl group introduced into a side chain can also be used. The addition acrylate polymer can be a copolymer of a (meth) acrylate and a monomer having a crosslinkable functional group in a molecule, and a part of the crosslinkable functional group of the copolymer, It is obtained by reacting with a compound having a group reactive with a (meth) acrylonitrile group and a crosslinkable functional group.

The weight average molecular weight of the above-mentioned addition acrylate-based polymer is preferably from 50,000 to 900,000, particularly preferably from about 100,000 to about 500,000.

The active energy ray-curable component (E) may be selected from the above-mentioned polyfunctional acrylate-based monomer, acrylate-based oligomer, and addition acrylate-based polymer, or may be used in combination of two or more types. It is used in combination with active energy ray curable components other than these.

The content of the active energy ray-curable component (E) in the adhesive composition P is preferably from 1 to 40 parts by mass per 100 parts by mass of the (meth) acrylate copolymer (A), and particularly preferably from 5 to 30 parts by mass. Preferably, 10 to 20 parts by mass is further preferred.

(6) Various additives

The adhesive composition P may contain various additives commonly used in acrylic adhesives, such as an antistatic agent, an adhesion-imparting agent, an antioxidant, a light stabilizer, a softener, a filler, a refractive index adjuster, etc., as needed. Especially when When the adhesive composition P contains the active energy ray-curable component (E), it is preferred to contain a photopolymerization initiator. By containing a photopolymerization initiator, the active energy ray-curable component (E) can be effectively cured, and the polymerization hardening time and the amount of irradiation of the active energy ray can be reduced.

Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, and 2, 2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one , 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy) Phenyl-2-(hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone , 2-methyl hydrazine, 2-ethyl hydrazine, 2-tert-butyl hydrazine, 2-amino hydrazine, 2-methyl thioxanthone, 2-ethyl thioxanthone, 2-chlorothiazide Tons of ketone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal, acetophenone dimethyl ketal, p-dimethylamino benzophenone Acid ester, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]acetone], 2,4,6-trimethylbenzylidene-diphenyl - phosphine oxide, etc. These may be used alone or in combination of two or more.

The photopolymerization initiator is preferably 0.1 to 20 parts by mass based on 100 parts by mass of the active energy ray-curable component (E), and is preferably used in an amount of from 1 to 12 parts by mass.

(7) Manufacture of adhesive composition

The adhesive composition P can be produced by mixing the (meth) acrylate copolymer (A) and the obtained (meth) acrylate copolymer (A), the crosslinking agent (B), and the eucalyptus oil (C). And add decane coupling agent (D) as needed, live The performance is produced by using a radiation curable component (E), an additive, or the like.

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

Examples of the polymerization initiator include an azo compound, an organic peroxide, and the like, and two or more types may be used in combination. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), and 1,1'-azobis (cyclohexane). Alkane 1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxypentyl) Nitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis 2-hydroxymethylpropionitrile), 2,2'-azobis[2-(2-imidazolin-2-yl)propane, and the like.

Examples of the organic peroxide include benzammonium peroxide, t-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and (2-ethoxyethyl)peroxydicarbonate, tert-butyl peroxy neodecanoate, tert-butyl peroxypivalate, (3,5,5-trimethylhexyl) peroxide, Dipropylene peroxide, diethyl hydrazine peroxide, etc.

Further, in the above polymerization process, the weight average molecular weight of the obtained polymer can be adjusted by blending a chain transfer agent such as 2-mercaptoethanol.

When the (meth) acrylate copolymer (A) is obtained, a crosslinking agent (B), an eucalyptus oil (C), and a decane coupling agent according to the desired one are added to the solution of the (meth) acrylate copolymer (A). (D), active energy ray hardening The component (E), the additive, the diluent solvent, and the like are sufficiently mixed, whereby an adhesive composition P (coating solution) diluted with a solvent is obtained. Further, when a solid matter is used in any of the above components, or when precipitation occurs when it is mixed with other components in an undiluted state, the component may be separately dissolved or diluted in a diluent solvent, and the like. Ingredients are mixed.

Examples of the diluent solvent include an aliphatic hydrocarbon such as hexane, heptane or cyclohexane, an aromatic hydrocarbon such as toluene or xylene, a halogenated hydrocarbon such as dichloromethane or dichloroethane, methanol, ethanol or propanol. Alcohols such as butanol and 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone, ethyl acetate, butyl acetate, etc. A cellosolve such as a solvent is a solvent or the like.

The concentration and viscosity of the coating solution thus prepared are not particularly limited as long as they are within the range of the coatable layer, and may be appropriately selected depending on the situation. For example, the concentration of the adhesive composition P diluted is 10 to 60% by mass. Further, when the coating solution is obtained, the addition of a diluent solvent or the like is not a requirement, and the diluent solvent may not be added as long as the adhesive composition P is a coatable viscosity or the like. At this time, the adhesive composition P is a coating solution in which the polymerization solvent of the (meth) acrylate copolymer (A) is directly used as a diluent solvent.

(8) Manufacture of adhesives

An adhesive (adhesive layer) can be obtained by applying the above adhesive composition P to a desired object and then crosslinking.

The crosslinking of the adhesive composition P can be carried out by heat treatment. It is also possible to use the drying treatment after applying the adhesive composition P as the heat treatment. The heating temperature of the heat treatment is preferably from 50 to 150 ° C, particularly preferably from 70 to 120 ° C. Moreover, the heating time is preferably from 10 seconds to 10 minutes, and is preferably from 50 seconds to 2 minutes. Zhong is especially good.

After the heat treatment, if necessary, a curing period of about 1 to 2 weeks at normal temperature (for example, 23 ° C, 50% RH) may be provided. When the curing period is required, an adhesive is formed after the curing period, and when the curing period is not required, the adhesive is formed after the end of the heat treatment.

By the above heat treatment (and curing), the (meth) acrylate copolymer (A) is sufficiently crosslinked by the crosslinking agent (B). The pressure-sensitive adhesive layer thus obtained is excellent in step followability, and is excellent in step-followability even under high-temperature and high-humidity conditions, and is excellent in reworkability.

Further, when the adhesive composition P contains the active energy ray-curable component (E), as described above, the adhesive composition P can be applied to a desired object and subjected to heat treatment, followed by active energy rays. The irradiation causes the adhesive composition P to be hardened to form an adhesive (adhesive layer), but it is preferable to apply the active energy ray after attaching to the adherend in a state before the active energy ray irradiation. As a result, the segmentation followability in the initial stage is more excellent.

(9) Thickness of the adhesive layer

The thickness of the adhesive layer of the adhesive sheet according to the present embodiment (value measured in accordance with JIS K7130) is preferably 10 to 1000 μm, more preferably 30 to 400 μm, and particularly preferably 50 to 300 μm. Further, the adhesive layer may be formed in a single layer or may be formed by laminating a plurality of layers.

When the thickness of the adhesive layer is 10 μm or more, the desired adhesive force is easily exhibited, and sufficient step followability can be ensured for the normal step of the display member. In addition, when the thickness of the adhesive layer is 1000 μm or less, the workability is good.

(10) Physical properties of the adhesive (adhesive layer)

(10-1) Gel fraction

The adhesive of the adhesive layer constituting the adhesive sheet of the present embodiment has a gel fraction of 40 to 90%, preferably 45 to 80%, more preferably 48 to 75%. When the gel fraction of the adhesive is less than 40%, the step-followability of the step under high-temperature and high-humidity conditions is deteriorated, and bubbles, floating, peeling, and the like are likely to occur in the vicinity of the step. On the other hand, when the gel fraction of the adhesive exceeds 90%, the adhesive becomes too hard, and the initial step followability deteriorates, and bubbles or floats are likely to occur in the vicinity of the step. The method for measuring the gel fraction of the adhesive is as shown in the test examples described later.

Further, when the adhesive composition P contains the active energy ray-curable component (E), it is preferred that the adhesive satisfies the gel fraction before and after the active energy ray irradiation.

(10-2) Adhesion

The adhesive sheet of the present embodiment has an adhesion to the alkali-free glass of 15 to 26 N/25 mm, preferably 16 to 24 N/25 mm, and particularly preferably 17 to 20 N/25 mm. When the adhesive force of the adhesive sheet is less than 15 N/25 mm, the step-followability of the step under high-temperature and high-humidity conditions is deteriorated, and bubbles, floating, peeling, and the like are likely to occur in the vicinity of the step. On the other hand, if the adhesive force of the adhesive sheet exceeds 26 N/25 mm, the reworkability deteriorates. In other words, when the adhesive member is in the above-described range, when the display member having one of the steps on the side of the bonding surface is bonded to the other display member constituting member, the reworkability can be ensured and the reworkability can be ensured. Effectively prevent floating, peeling, and the like.

Further, when the adhesive composition P contains the active energy ray-curable component (E), it is preferable to satisfy the above-described adhesive force before and after the active energy ray irradiation.

Here, the adhesive force in the present specification basically means an adhesive force measured by a 180° peeling method according to JIS Z0237:2009, and the measurement sample is set to have a width of 25 mm and a length of 100 mm, and the measurement sample is 0.5 MPa, 50. After being pressed at ° C for 20 minutes and attached to the adherend, it was allowed to stand under normal pressure, 23 ° C, and 50% RH for 24 hours, and then measured at a peeling speed of 300 mm/min.

(10-3) haze value

The adhesive layer of the pressure-sensitive adhesive sheet of the present embodiment preferably has a haze value of 1.0% or less, more preferably 0.7% or less, and still more preferably 0.5% or less. When the haze value of the adhesive layer is 1.0% or less, the transparency is extremely high, and it is suitable for optical use (for display). This haze value can be achieved by appropriately adjusting the type and amount of the eucalyptus oil (C). In addition, the haze value in this specification is set to the value measured by JIS K7136:2000.

(11) The specific composition of the adhesive sheet

A specific configuration of an example of the adhesive sheet of the present embodiment is shown in Fig. 1.

As shown in Fig. 1, the adhesive sheet 1 of one embodiment is composed of two release sheets 12a and 12b and two release sheets which are in contact with the peeling faces of the two release sheets 12a and 12b. Adhesive layer 11 held by 12a, 12b. In addition, the peeling surface of the peeling sheet in this specification is the surface which has the peeling property in the peeling sheet, and is the surface which carried out the peeling process, and the surface which shows the peeling-

The release sheets 12a and 12b are protected from the adhesive layer before the adhesive sheet is used, and are peeled off when the adhesive sheet (adhesive layer) is used. In the adhesive sheet 1 of the present embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

As the release sheets 12a and 12b, 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, or a polyparaphenylene is used. Ethylene formate film, polyethylene naphthalate film, polybutylene terephthalate film, urethane film, ethylene ethyl acetate film, ionomer resin film, ethylene ‧ (methyl) An acrylic copolymer film, a vinyl ‧ (meth) acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, a fluororesin film, or the like. Further, these crosslinked films can also be used. Alternatively, these laminated films may be used.

It is preferable that the release surface of the release sheets 12a and 12b (especially the surface in contact with the adhesive layer 11) is subjected to a release treatment. Examples of the release agent used in the release treatment include an alkyd type, an anthrone type, a fluorine type, an unsaturated polyester type, a polyolefin type, and a wax type release agent. Further, in the release sheets 12a and 12b, one release sheet is a heavy release type release sheet having a large peeling force, and the other release sheet is preferably a light release type release sheet having a small peeling force.

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

(12) Manufacture of adhesive sheets

As a production example of the adhesive sheet 1, the coating liquid of the above-mentioned adhesive composition P is applied to the peeling surface of one release sheet 12a (or 12b), and heat treatment is performed to thermally crosslink the adhesive composition P. After the coating layer is formed, the peeling surface of the other release sheet 12b (or 12a) is superposed on the coating layer. When a curing period is required, the coating layer becomes the adhesive layer 11 by the curing period, and the coating layer directly becomes the adhesive layer 11 when no curing period is required. In addition, When the adhesive composition P contains the active energy ray-curable component (E), the coating layer (adhesive layer 11) may be irradiated with an active energy ray after the heat treatment. By the above process, the adhesive sheet 1 can be obtained. The heat treatment and curing conditions are as described above.

In another example of the production of the adhesive sheet 1, the coating liquid of the above-mentioned adhesive composition P is applied to the peeling surface of one of the release sheets 12a, and heat treatment is performed to thermally crosslink the adhesive composition P to form a coating. The layer was obtained to obtain a release sheet 12a with a coating layer. Then, the coating liquid of the above-mentioned adhesive composition P is applied onto the peeling surface of the other release sheet 12b, and heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer, thereby obtaining a coating layer. The release sheet 12b of the layer. Further, the release sheet 12a with the coating layer and the release sheet 12b with the coating layer were bonded to each other so that the two coating layers were in contact with each other. When a curing period is required, the above-mentioned laminated coating layer becomes the adhesive layer 11 through the curing period, and when the curing period is not required, the laminated coating layer directly becomes the adhesive layer 11. In the production example, when the adhesive composition P contains the active energy ray-curable component (E), the coating layer (adhesive layer 11) may be irradiated with an active energy ray after the bonding. The above adhesive sheet 1 can be obtained by the above process. According to this production example, even when the adhesive layer 11 is thick, it can be stably manufactured.

As a method of applying the coating liquid of the above-mentioned adhesive composition P, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used. .

[display body]

As shown in Fig. 2, the display body 2 of the present embodiment includes the following configuration: a first display body constituting member 21 (a display body constituting member) having a step on the side where the bonding is less; a second display constituting member 22 (another display body constituting member); and being located between the The adhesive layer 11 to which the first display body constituent member 21 and the second display body constituent member 22 are bonded to each other. In the display 2 of the present embodiment, the first display member constituting member 21 has a step on the surface on the side of the adhesive layer 11, and specifically has a step formed by the printed layer 3.

The adhesive layer 11 in the display body 2 is the adhesive layer 11 of the adhesive sheet 1.

Examples of the display body 2 include a liquid crystal (LCD) display, a light-emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, and the like, and may be a touch panel. Further, the display body 2 may be a member constituting a part of the components.

The first display member constituting member 21 may be a glass plate, a plastic plate or the like, and is preferably a protective plate including a laminate or the like. These are usually hard bodies. At this time, the printed layer 3 is generally formed in a frame shape on the side of the adhesive layer 11 in the first display body constituent member 21.

The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium-containing glass, aluminosilicate glass, lead glass, and borosilicate glass. Bismuth borate glass and the like. The thickness of the glass plate is not particularly limited, and is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate. The thickness of the plastic plate is not particularly limited, and is usually 0.2 to 5 mm, and 0.4 to 3 mm is preferable.

Further, various functional layers (a transparent conductive film, a metal layer, a silicon oxide layer, a hard coat layer, an antiglare layer, etc.) may be provided on one or both sides of the glass plate or the plastic plate, or an optical member may be laminated. Also, the transparent conductive film and the metal layer can be patterned.

The second display body constituent member 22 is an optical member or a display body module to be attached to the first display body constituent member 21 (for example, a liquid crystal (LCD) module, a light emitting diode (LED) module, and an organic electroluminescence. A light-emitting (organic EL) module or the like or a laminate including a display body module is preferred. These are usually hard bodies. Further, the second display body constituent member 22 may be an optical member that is a part of the display body module.

Examples of the optical member include a scattering preventing film, a polarizing plate (polarizing film), a polarizer, a phase difference plate (phase difference film), a viewing angle compensation film, a brightness enhancement film, a contrast improving film, and a liquid crystal polymer film. A diffusion film, a transflective film, a transparent conductive film, or the like. As the scattering preventing film, a hard coat film obtained by forming a hard coat layer on one surface of a base film can be exemplified.

The material constituting the printed layer 3 is not particularly limited, and a known material for printing can be used. The thickness of the printed layer 3, that is, the height of the step is preferably 3 to 45 μm, more preferably 5 to 35 μm, further preferably 7 to 25 μm, and most preferably 10 to 20 μm.

When the display body 2 is manufactured, as an example, one peeling sheet 12a of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to the side where the printed layer 3 of the first display body constituent member 21 exists. Face. At this time, since the adhesive layer 11 is excellent in step followability, it can be suppressed by the printed layer 3 A gap or float occurs near the step formed.

Thereafter, the other release sheet 12b is peeled off from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to the second display constituent member 22 to obtain the display body 2. In this case, even when the bonding position of the second display member constituting member 22 is deviated, the adhesive layer 11 is excellent in reworkability, so that the adhesive layer 11 can be easily peeled off from the second display member constituting member 22. And a laminated body of the first display body constituent member 21. In particular, even if the hard bodies are mutually separated, they can be easily peeled off. Thereby, at least the second display body constituent member 22 can be reused.

When the adhesive composition P contains the active energy ray-curable component (E), the laminate of the first display constituent member 21 and the adhesive layer 11 and the second display constituent member 22 are bonded together. It is preferable that the adhesive layer 11 is irradiated with an active energy ray and the adhesive layer 11 is cured by the first display member 21 or the second display member 22 interposed therebetween.

The active energy ray means an energy source having an electromagnetic wave or a charged particle beam, and specific examples thereof include ultraviolet rays, electron beams, and the like. In the active energy ray, it is particularly preferable to operate the ultraviolet ray easily.

The irradiation of ultraviolet rays can be carried out by a high pressure mercury lamp, a fused H lamp, a xenon lamp or the like, and the illuminance is preferably about 50 to 1000 mW/cm ² with respect to the amount of ultraviolet rays. Further, the light amount of 50 ~ 10000mJ / cm ² is preferred, 80 ~ 5000mJ / cm ² is more excellent, 100 ~ 1000mJ / cm ² is particularly preferred. On the other hand, the irradiation of the electron beam can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 to 1000 krad.

The adhesive layer 11 in the above display body 2 is even in a high temperature and high humidity strip. In the case where the display body 2 is placed under the conditions of, for example, 85 ° C and 85% RH for 72 hours, it is possible to suppress generation of bubbles, floating, peeling, etc. in the vicinity of the step formed by the printed layer 3 . .

The embodiments described above are described in order to facilitate the understanding of the present invention, and are not intended to limit the present invention. Therefore, the various embodiments disclosed in the above embodiments are intended to encompass all design changes and equivalents of the technical scope of the invention.

For example, any one or both of the release sheets 12a, 12b in the adhesive sheet 1 may be omitted, and a desired optical member may be laminated instead of the release sheets 12a and/or 12b. Further, the first display body constituent member 21 may have a step other than the printed layer 3. Further, not only the first display body constituent member 21 but also the second display body constituent member 22 may have a step on the side of the adhesive layer 11.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the scope of the invention is not limited to the embodiments.

[Example 1]

1. Preparation of (meth) acrylate copolymer

(Meth) acrylate copolymerization by copolymerizing 60 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of isobornyl acrylate, 10 parts by mass of N-propylene decylmorpholine and 20 parts by mass of 2-hydroxyethyl acrylate (A). The molecular weight of the (meth) acrylate copolymer (A) was measured by the method described later, and the weight average molecular weight (Mw) was 500,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylate copolymer (A) obtained in the above Process 1 (solid content conversion value; the same applies hereinafter), and trimethylolpropane-modified toluene diisocyanate as the crosslinking agent (B) (manufactured by TOYOCHEM CO., LTD., product name "BHS8515") 0.30 parts by mass, as a two-terminal amine-modified dimethyl polysiloxane of eucalyptus oil (C) (manufactured by Shin-Etsu Silicone Co., Ltd., Product name "KF-8010", viscosity: 12 mm ² /s, functional group equivalent: 430 g/mol) 0.5 parts by mass, and 3-glycidoxypropyltrimethoxydecane as decane coupling agent (D) (Shin -Etsu Chemical Co., Ltd., product name "KBM403") 0.2 parts by mass, mixed well, and diluted with methyl ethyl ketone, thereby obtaining a coating solution of an adhesive composition having a solid concentration of 35% by mass. .

3. Manufacture of adhesive sheets

The peeling-treated surface of the heavy-peelable release sheet (product name "SP-PET752150" manufactured by LINTEC Corporation) obtained by peeling off one side of the polyethylene terephthalate film by an oxime-based release agent is used. A coating solution of the obtained adhesive composition was applied by a knife coater. Then, the coating layer was heat-treated at 90 ° C for 1 minute to form a coating layer.

Then, the coating layer on the heavy release release sheet obtained above and the one side of the polyethylene terephthalate film were subjected to a release treatment by a decyl ketone release agent (manufactured by LINTEC Corporation). The product name "SP-PET382120" was bonded to the peeling-treated surface of the light-peelable release sheet and the coating layer, and cured at 23 ° C and 50% RH for 7 days. An adhesive sheet having a structure of a heavy release type release sheet/adhesive layer (thickness: 50 μm)/light release type release sheet was produced. In addition, the layer of the adhesive The thickness is a value measured by a constant pressure thickness measuring instrument (manufactured by TECLOCK Corporation, product name "PG-02") in accordance with JIS K7130.

Here, each compound (solid content conversion value) of the adhesive composition when the (meth) acrylate copolymer (A) is 100 parts by mass (solid content conversion value) 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

IBXA: Isobornyl acrylate

ACMO: N-propylene decylmorpholine

HEA: 2-hydroxyethyl acrylate

BA: n-butyl acrylate

AA: Acrylic

[crosslinking agent]

TDI system: Trimethylolpropane modified toluene diisocyanate (manufactured by TOYOCHEM CO., LTD., product name "BHS8515")

Epoxy type: 1,3-bis(diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc., product name "TETRAD-C")

[矽油]

KF-8010: a two-terminal amine-modified dimethyl polysiloxane (manufactured by Shin-Etsu Silicone Co., Ltd., product name "KF-8010", viscosity: 12 mm ² /s, functional group equivalent: 430 g / Mol)

KF-105: a two-terminal epoxy-modified dimethyl polyoxane (manufactured by Shin-Etsu Silicone Co., Ltd., product name "KF-105", viscosity: 15 mm ² /s, functional group equivalent: 490 g /mol)

KF-2012: Single-end methacrylic acid-modified dimethyl polydecane (manufactured by Shin-Etsu Silicone Co., Ltd., product name "KF-2012", viscosity: 60 mm ² /s, functional group equivalent: 4600 g /mol)

[Examples 2 to 6 and Comparative Examples 1 to 8]

The type and ratio of each monomer constituting the (meth) acrylate copolymer (A), the weight average molecular weight of the (meth) acrylate copolymer (A), and the crosslinking agent (B) were changed as shown in Table 1. An adhesive sheet was produced in the same manner as in Example 1 except for the type and ratio of the type and the ratio of the oil (C).

[Example 7]

1. Preparation of (meth) acrylate copolymer

The (meth) acrylate copolymer (A) was prepared by copolymerizing 90 parts by mass of n-butyl acrylate and 10 parts by mass of acrylic acid. The molecular weight of the (meth) acrylate copolymer (A) was measured by the method described later, and the weight average molecular weight (Mw) was 400,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylate copolymer (A) obtained in the above Process 1, and 1,3-bis(diglycidylaminomethyl)cyclohexane as a crosslinking agent (B) 0.06 parts by mass, manufactured by Mitsubishi Gas Chemical Company, Inc., product name "TETRAD-C"), as a two-terminal amine-modified dimethyl polyoxane of eucalyptus oil (C) (Shin-Etsu Silicone Co., Ltd. , product name "KF-8010", viscosity: 12 mm ² /s, functional group equivalent: 430 g / mol) 0.5 parts by mass, as a decane coupling agent (D) 3-glycidoxypropyl trimethoxy decane ( Shin-Etsu Chemical Co., Ltd., product name "KBM403") 0.2 parts by mass of ε-caprolactone modified tris-(2-propenyloxyethyl) as active energy ray hardening component (E) Isocyanurate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-9300-1CL") 10 parts by mass, and 1-hydroxycyclohexyl phenyl ketone (BASF) as a photopolymerization initiator 1 part by mass of the company, product name "IRGACURE 184") was mixed and thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of an adhesive composition having a solid concentration of 35% by mass.

3. Manufacture of adhesive sheets

An adhesive sheet was produced in the same manner as in Example 1 except that the coating solution of the obtained adhesive composition was used. Further, the adhesive sheet obtained in the present embodiment is a person who applies energy rays to the adhesive layer after being attached to the adherend.

Here, the weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement conditions>

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

‧GPC column (passed in the following order): TOSOH CORPORATION TSK guard column HXL-H TSK gel GMHXL (×2) TSK gel G2000HXL

‧ Determination of solvent: tetrahydrofuran

‧Measurement temperature: 40 ° C

[Test Example 1] (Measurement of gel fraction)

The adhesive sheets obtained in the examples and the comparative examples were cut into 80 mm×80 mm. The size of the adhesive is wrapped in a polyester mesh (mesh size 200), and the quality of the adhesive itself is calculated by weighing the mass by a precision balance and subtracting the individual mass of the mesh. Set the quality at this time to M1.

Next, the adhesive wrapped in the above polyester web was immersed in ethyl acetate at room temperature (23 ° C) for 24 hours. Thereafter, the adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C and a relative humidity of 50%, and dried in an oven at 80 ° C for 12 hours. After drying, the quality of the adhesive itself is calculated by weighing the mass by a precision balance and subtracting the individual mass of the above net. Set the quality at this time to M2. The gel fraction (%) is represented by (M2/M1) × 100. The results are shown in Table 2.

Further, with respect to the adhesive sheet of Example 7, the gel fraction of the adhesive layer before and after irradiation with ultraviolet rays (irradiation from the side of the heavy release type release sheet) was measured. The irradiation conditions of ultraviolet rays are as follows.

<Ultraviolet irradiation conditions>

‧Use electrodeless lamp H bulb made by Fusion, Co., Ltd.

‧illuminance 500mW/cm ² , light quantity 200mJ/cm ²

‧UV illuminance ‧The light meter uses "UVPF-36" manufactured by EYE GRAPHICS Co., Ltd.

[Test Example 2] (Measurement of haze value)

For the adhesive layer of the adhesive sheet obtained in the examples and the comparative examples, the haze value was measured in accordance with JIS K7136:2000 using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., LTD., product name "NDH-2000"). (%). The results are shown in Table 2.

[Test Example 3] (Measurement of adhesion)

The light release release sheet was peeled off from the adhesive sheets obtained in the examples and the comparative examples, and the exposed adhesive layer was attached to a polyethylene terephthalate (PET) film having an easy adhesion layer (TOYOBO CO.). A laminate of the product name "PET A4300", thickness: 100 μm), which is a product of a release sheet/adhesive layer/PET film. The obtained laminate was cut into a width of 25 mm and a length of 100 mm, and this was used as a sample.

The peel-off release sheet was peeled off from the above sample in an environment of 23 ° C and 50% RH, and the exposed adhesive layer was attached to an alkali-free glass (Eagle XG, manufactured by Corning Incorporated), and Kurihara Manufactory Inc was used. The autoclave was pressurized at 0.5 MPa and 50 ° C for 20 minutes. Thereafter, the mixture was allowed to stand under the conditions of 23 ° C and 50% RH for 24 hours, and then the adhesion was measured under the conditions of a peeling speed of 300 mm/min and a peeling angle of 180 degrees using a tensile tester (manufactured by ORIENTEC Co., Ltd., Tensilon). Force (N/25mm). Conditions other than those described herein were measured in accordance with JIS Z 0237:2009. The results are shown in Table 2.

In the same manner as described above, the adhesive sheet of the seventh embodiment is attached to the alkali-free glass and pressurized in an autoclave, and then the adhesive layer is irradiated with ultraviolet rays through the PET film, and then, in the same manner as described above. The adhesion after 24 hours of placement was also measured. The irradiation conditions of the ultraviolet rays were the same as in Test Example 1.

[Test Example 4] (Evaluation of reworkability)

The adhesion of Test Example 3 was measured, and after the adhesive sheet was peeled off, the area of the residue on the surface of the alkali-free glass (adhesive surface of the adhesive) as the adherend was measured, and the reworkability was evaluated according to the following criteria. The results are shown in Table 2.

◎... There is no residue at all.

○... There is a residue on the area smaller than 5% of the bonding area.

△... There is a residue on the area of 5% or more and less than 20% of the bonding area.

×... There is a residue on the area of 20% or more of the bonding area.

[Test Example 5] (Evaluation of step followability)

In the glass plate (manufactured by NSG Precision Co., Ltd., product name "Corning glass Eagle XG", vertical 90 mm × width 50 mm × thickness 0.5 mm), the coating thickness was 20 μm, and the shape was framed (shape: Screen printing UV-curable ink (manufactured by Teikoku Printing Inks Mfg. Co., Ltd., product name "POS-911 Ink"), 90 mm in length × 50 mm in width, and 5 mm in width). Next, ultraviolet rays (80 W/cm ² , two metal halide lamps, a lamp height of 15 cm, and a belt speed of 10 to 15 m/min) were irradiated to harden the printed ultraviolet curable ink, thereby producing a step (step difference) formed by printing. Height: 20 μm) with a stepped glass plate.

The light release type release sheet was peeled off from the adhesive sheets obtained in the examples and the comparative examples, and the exposed adhesive layer was attached to a PET film having an easy adhesion layer (TOYOBO CO., LTD., product name "PET" A4300", thickness: 100μm) easy adhesion layer. Next, the heavy release type release sheet was peeled off to expose the surface of the adhesive layer. Further, the laminated layer was laminated on a glass plate with a stepped surface so that the entire printed surface of the frame was covered with an adhesive layer (manufactured by FUJIPLA Inc., product name "LPD3214"), and this was used as a sample for evaluation.

Further, in the adhesive sheet of Example 7, the laminated layer was placed on the stepped glass plate, and the adhesive layer was irradiated with ultraviolet rays through a PET film as a sample for evaluation. The irradiation conditions of the ultraviolet rays were the same as in Test Example 1.

The obtained sample for evaluation was autoclaved for 30 minutes at 50 ° C and 0.5 MPa, and then placed under normal pressure, 23 ° C, and 50% RH. hour. Subsequently, it was stored under high temperature and high humidity conditions of 85 ° C and 85% RH for 72 hours (endurance test), and thereafter, the step followability was evaluated. The step followability is judged based on whether the printing step difference is completely filled by the adhesive layer, and when the bubble difference, the floating, the peeling, etc. are not observed at the interface between the printing step and the adhesive layer, the step followability is good (○), when When the boundary between the printing step and the adhesive layer was observed as bubbles, float, peeling, etc., it was evaluated as poor step followability (x). The results are shown in Table 2.

[Test Example 6] (Evaluation of resistance to wet heat whitening)

The laminate of the adhesive sheets obtained in the examples or the comparative examples was sandwiched between two sheets of non-alkaline glass having a thickness of 1.1 mm to obtain a laminate. Further, in the adhesive layer of the adhesive sheet of Example 7, ultraviolet rays were irradiated through the glass under the ultraviolet irradiation conditions of Test Example 1. The haze value (%) was measured in accordance with JIS K7136:2000 using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., LTD., product name "NDH2000").

Next, the laminate was stored under humid heat conditions of 85 ° C and 85% RH for 240 hours. Then, it was returned to normal temperature and humidity of 23 ° C and 50% RH, and the haze was measured by a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., LTD., product name "NDH2000") in accordance with JIS K7136:2000. value(%). In addition, the haze value was measured within 30 minutes after returning the laminated body to normal temperature and normal humidity.

Based on the above results, the haze value before the damp heat condition was subtracted from the haze value after the damp heat condition to calculate the haze value increase (percentage) after the damp heat condition. When the haze value after the damp heat condition is increased by less than 1.0%, the wet heat whitening property is evaluated as good (○), and the haze value after the damp heat condition is increased to 1.0% or more and less than 5.0%, and the wet heat whitening property is evaluated as an appropriate value. Inside (Δ), when the haze value after the moist heat condition was increased by 5.0% or more, it was evaluated as poor wet heat whitening property (×). The results are shown in Table 2.

As can be seen from Table 2, the adhesive layer obtained in the examples has It has excellent optical properties (haze value), excellent step-followability (under high temperature and high humidity conditions), excellent reworkability, and excellent wet heat whitening resistance.

[Industrial availability]

The adhesive sheet of the present invention can be suitably used, for example, for bonding a protective sheet having a step and a desired display member.

1‧‧‧Adhesive film

11‧‧‧Adhesive layer

12a, 12b‧‧‧ peeling film

Claims (8)

An adhesive sheet having an adhesive layer for adhering a display member having a step on at least a side of a side of a bonding surface to another display member constituting member, characterized in that: the adhesive The layer is composed of an adhesive obtained by crosslinking an adhesive composition, and the adhesive composition comprises: (meth) acrylate copolymer (A); a crosslinking agent (B); and eucalyptus oil (C), the foregoing ( The methyl acrylate copolymer (A) contains 7 to 40% by mass of a hydroxyl group-containing monomer or 6 to 20% by mass of a carboxyl group-containing monomer as a monomer unit constituting the copolymer, and the gel of the above-mentioned adhesive The fraction is 40 to 90%, and the adhesion of the aforementioned adhesive sheet to the alkali-free glass is 15 to 26 N/25 mm. The adhesive sheet according to claim 1, wherein the content of the eucalyptus oil (C) in the adhesive composition is 0.01 to 1.8 based on 100 parts by mass of the (meth) acrylate copolymer (A). Parts by mass. The adhesive sheet according to claim 1, wherein the eucalyptus oil (C) has a functional group. The adhesive sheet according to claim 1, wherein the eucalyptus oil (C) has a viscosity of 5 to 100 mm ² /sec at 25 ° C. The adhesive sheet according to claim 1, wherein the (meth) acrylate copolymer (A) contains an alicyclic structure-containing monomer and a nitrogen atom-containing single The body serves as a monomer unit constituting the copolymer. The adhesive sheet according to claim 1, wherein the adhesive layer has a haze value of 1.0% or less. The adhesive sheet according to claim 1, wherein the adhesive sheet comprises two release sheets, and the adhesive layer is sandwiched by the release sheet so as to be in contact with the peeling surface of the two release sheets. A display body comprising: at least one side of the surface on which the bonding is provided has a step forming body constituting member; the other display body constituting member; and the one display body constituting member and the other display body constituting member are attached to each other The adhesive layer is characterized in that the adhesive layer is an adhesive layer of the adhesive sheet according to any one of claims 1 to 7.