TW201723125A - Adhesive composition, adhesive, adhesive sheet and display being excellent in reworkability while maintaining the property of being an adhesive for a display - Google Patents

Abstract

Provided are an adhesive composition which maintains the property of being an adhesive for a display and excellent in reworkability, an adhesive, an adhesive sheet and a display. An adhesive composition which is used for forming an adhesive layer for bonding a display component and another display component, comprising a (meth)acrylate ester copolymer (A), a crosslinking agent (B), and a compound (C). The (meth)acrylate ester copolymer (A) comprises a reactive group-containing monomer having in its molecule a reactive group that reacts with the crosslinking agent (B) as a monomer unit constituting the polymer, and has a weight average molecular weight above 400,000 and below 1,300,000; the compound (C) has an alkylene oxide moiety and does not have or has one reactive group that reacts with the crosslinking agent (B).

Description

Adhesive composition, adhesive, adhesive sheet and display body

The present invention relates to an adhesive composition for adhering a display member constituting member, an adhesive, an adhesive sheet, 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 difference. The reflection loss of raw 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 Patent Laid-Open 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, it is more difficult to bond the hard materials (hard bodies) such as the protective panel and the display body module to each other by the adhesive sheet, and it is more difficult 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 reduced. Therefore, it is expected that the adhesive sheet as described above will be able to The reworkability of the two hard bodies peeled off by the adhesive sheet can at least reuse the display body module.

The present invention has been made in view of such an actual situation, and an object thereof is to provide an adhesive composition, an adhesive, an adhesive sheet, and a display body which are excellent in reworkability while maintaining the performance as an adhesive for a display body.

In order to achieve the above object, the present invention provides an adhesive composition for forming an adhesive layer which is bonded to a display body constituent member and another display body constituent member, and is characterized in that it contains: (meth)acrylic acid. Ester copolymer (A); crosslinking agent (B); and compound (C), the (meth) acrylate copolymer (A) containing a reactive group having a reaction with the aforementioned crosslinking agent (B) in the molecule The reactive group-containing monomer is a monomer unit constituting the polymer, and has a weight average molecular weight of 400,000 or more and 1.3 million or less. The compound (C) has an alkylene oxide moiety and does not have or has one The reactive group in which the crosslinking agent (B) reacts (Invention 1).

The adhesive obtained by crosslinking the adhesive composition of the above invention (Invention 1) exhibits good flexibility by the (meth) acrylate copolymer (A) having a relatively low weight average molecular weight. Excellent segmental follow-up. In addition, the adhesive (B) contains the compound (C) and is excellent in reworkability while maintaining the performance as an adhesive for a display.

In the above invention (Invention 1), the compound (C) has a linear structure, has an alkyl group at both terminals or one end thereof (Invention 2), or the aforementioned compound (C) has a linear structure and It is preferred that the terminal or one end has a (meth) acrylonitrile group (Invention 3).

In the above invention (Inventions 1 to 3), the compound (C) is preferably contained in an amount of 0.2 part by mass or more and less than 10 parts by mass based on 100 parts by mass of the (meth)acrylate copolymer (A) (Invention 4) ).

In the above invention (Inventions 1 to 4), it is preferred that the (meth) acrylate copolymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer (Invention 5).

In the above inventions (Inventions 1 to 5), it is preferable that the one display body constituent member and the other display body constituent member are hard bodies (Invention 6).

In the above invention (Inventions 1 to 6), it is preferable that the display member constituent member has a step at least on the surface on the side to which it is bonded (Invention 7).

Secondly, the present invention provides an adhesive which is obtained by crosslinking the above-mentioned adhesive composition (Inventions 1 to 7) (Invention 8).

Thirdly, the present invention provides an adhesive sheet having an adhesive layer for bonding a display body constituent member and another display body constituent member, characterized in that the adhesive layer contains an adhesive (Invention 8) (Invention 9).

In the above invention (Invention 9), the thickness of the pressure-sensitive adhesive layer is preferably 20 μm or more and 500 μm or less (Invention 10).

In the above invention (Inventions 9 and 10), the pressure-sensitive adhesive sheet includes two release sheets, and the pressure-sensitive adhesive layer is preferably sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets (Invention 11). .

Fourthly, the present invention provides a display body constituting member, another display body constituting member, and an adhesive layer which are bonded to each other to the display body constituting member and the other display body constituting member, characterized in that the adhesive layer is It is an adhesive layer of the adhesive sheet (Invention 9 to 11) (Invention 12).

Further, the present invention provides an adhesive sheet having an adhesive layer for bonding a display body constituent member and another display body constituent member, characterized in that the adhesive layer contains a (meth) acrylate copolymer. An adhesive obtained by crosslinking an adhesive composition of the substance (A), the crosslinking agent (B) and the compound (C), and the (meth) acrylate copolymer (A) contains an intra-molecular crosslinking agent (B) Reactive group-containing monomer having a reactive group as a monomer unit constituting the polymer, the compound (C) having an alkylene oxide moiety and having no or having a cross The compound of the reactive group in which the crosslinking agent (B) reacts has a thickness of the adhesive layer of 20 μm or more and 500 μm or less.

The adhesive composition, the adhesive, the adhesive sheet, and the display of the present invention can maintain the performance as an adhesive for a display body 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 composition]

The adhesive composition of the present embodiment (hereinafter sometimes referred to as "adhesive composition P") is an adhesive composition for forming an adhesive layer that bonds one display member and another display member. . The display body and the display body constituent member will be described later.

The adhesive composition P contains a (meth) acrylate copolymer (A), a crosslinking agent (B), and a compound (C), and further contains a decane coupling agent (D). Further, in the present specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. Other similar terms are the same.

The (meth) acrylate copolymer (A) contains a reactive group-containing monomer having a reactive group reactive with the crosslinking agent (B) as a monomer unit constituting the polymer, and has a weight average molecular weight of 400,000. Above and below 1.3 million. Further, the compound (C) is a compound having an alkylene oxide moiety and having no or a reactive group reactive with the crosslinking agent (B).

When the weight average molecular weight of the (meth) acrylate copolymer (A) is in a relatively low range as described above, the obtained adhesive exhibits good flexibility and is excellent in step followability. Further, the weight average molecular weight in the present specification is a standard polystyrene equivalent value measured by a gel permeation chromatography (GPC) method.

In addition, the adhesive agent P contains the above-mentioned compound (C), and the adhesive agent obtained by crosslinking the adhesive composition P is excellent in reworkability by maintaining the performance as an adhesive for a display body. In particular, as described above, when the weight average molecular weight of the (meth) acrylate copolymer (A) is relatively low, the obtained adhesive is soft and tends to be inferior in reworkability, but in the present embodiment, Excellent reworkability can be obtained by using the above compound (C). In other words, in the adhesive obtained by crosslinking the adhesive composition P, the compound (C) functions as an excellent rework agent. Therefore, the adhesive sheet having the adhesive layer containing the adhesive can be easily peeled off from the display constituent member even after being temporarily attached to the display constituent member. Reuse of the display body constituent members can be realized.

It is considered that the above-described excellent reworkability is mainly exhibited by the alkylene oxide moiety of the compound (C). Further, the compatibility with the (meth) acrylate copolymer (A) can be ensured by the fact that the compound (C) does not have or has a reactive group which reacts with the crosslinking agent (B). Further, the reaction of the (meth) acrylate copolymer (A) and the crosslinking agent (B) is not inhibited by the compound (C), and a good crosslinked structure can be formed, and the obtained adhesive exhibits a desired cohesive force. Therefore, the performance as an adhesive for a display body is maintained, and in particular, the step followability under high temperature and high humidity conditions can be satisfactorily exhibited.

(1) (meth) acrylate copolymer (A)

The (meth) acrylate copolymer (A) contains a reactive group-containing monomer having a reactive group reactive with the crosslinking agent (B) in the molecule as a monomer unit constituting the polymer. The reactive group derived from the reactive group-containing monomer reacts with the crosslinking agent (B) to form a crosslinked structure (three-dimensional network structure), and an adhesive having a desired cohesive force can be obtained.

The reactive group-containing monomer is preferably a monomer having a hydroxyl group in the molecule (hydroxy group-containing monomer), a monomer having a carboxyl group in the molecule (a carboxyl group-containing monomer), and a single molecule having an amine group in the molecule. Body (amine-containing monomer) and the like. Among these, a hydroxyl group-containing monomer which is excellent in reactivity with the crosslinking agent (B) and which has less adverse effects on the adherend is particularly preferable. Further, the carboxyl group-containing monomer is preferred from the viewpoint that the weight average molecular weight of the (meth) acrylate copolymer (A) is relatively low and the desired cohesive force is exhibited.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and (meth)acrylic acid 3- Hydroxypropyl ester, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc., such as hydroxyalkyl (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 and 4-hydroxybutyl (meth)acrylate are preferred, and 2-hydroxyethyl (meth)acrylate is particularly preferred. These may be used alone or in combination of two or more.

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.

Examples of the amine group-containing monomer include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. These may be used singly or in combination of two or more.

The (meth) acrylate copolymer (A) contains a hydroxyl group-containing monomer having a lower limit of 3% by mass or more, preferably as a monomer unit constituting the polymer, more preferably 10% by mass or more, and particularly preferably 15% by mass. More than % is further preferred. In addition, the (meth) acrylate copolymer (A) contains a hydroxyl group-containing monomer having an upper limit of 35% by mass or less, and is preferably a monomer unit constituting the polymer, and particularly preferably contains 30% by mass or less. 25 mass% or less is further preferable. When the (meth) acrylate copolymer (A) contains a hydroxyl group-containing monomer as a monomer unit in the above amount, a good crosslinked structure is formed in the obtained adhesive, and a desired cohesive force can be obtained, and the adhesive is obtained. Residual hydroxy base. a hydroxy-based hydrophilic group, if the hydrophilic group is present in the adhesive, even if the adhesive is placed under high temperature and high humidity conditions, and immersed in the adhesive under the high temperature and high humidity conditions The compatibility is also good, and as a result, it is possible to suppress whitening (excellent resistance to moist heat whitening) of the adhesive when the normal temperature and normal humidity are restored.

When the (meth) acrylate copolymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, the (meth) acrylate copolymer (A) contains the carboxyl group-containing monomer as follows, that is, The lower limit is preferably 5% by mass or more, more preferably 7% by mass or more, and still more preferably 10% by mass or more. In addition, the (meth) acrylate copolymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, that is, 30% by mass or less, and preferably 20% by mass or less, as the upper limit. It is especially preferable, and it is further preferable to contain 15 mass% or less. When the (meth) acrylate copolymer (A) contains a carboxyl group-containing monomer as a monomer unit in the above amount, a good crosslinked structure is formed in the obtained adhesive, and a desired cohesive force can be obtained.

Further, it is also preferred that the (meth) acrylate copolymer (A) does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Since the carboxyl group is an acid component, even if a carboxyl group-containing monomer is not contained, even if an acid is generated in a target to which the adhesive is attached, for example, Tin-doped indium oxide (ITO) or the like may be present. In the case of a transparent conductive film or a metal film, it is also possible to suppress such problems (corrosion, change in resistance value, etc.) caused by acid. Among them, a predetermined amount of the carboxyl group-containing monomer is allowed to be contained to the extent that the defect is not caused. Specifically, in the (meth) acrylate copolymer (A), a carboxyl group-containing monomer is allowed to be contained as a monomer unit in an amount of less than 5% by mass. The carboxyl group-containing monomer is preferably contained in an amount of 2% by mass or less, more preferably 0.1% by mass or less.

The (meth) acrylate copolymer (A) contains an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms as a monomer unit constituting the polymer, whereby a good adhesion can be exhibited. . 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 methacrylate, n-amyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (methyl) N-decyl acrylate, n-dodecyl (meth) acrylate, tetradecyl (meth) acrylate, cetyl (meth) acrylate, octadecyl (meth) acrylate, etc. . Among them, from the viewpoint of further improving the adhesion, a (meth) acrylate having an alkyl group having 1 to 8 carbon atoms is preferred, n-butyl (meth)acrylate or 2-ethyl (meth)acrylate. Hexyl ester is especially preferred. Further, these may be used alone or in combination of two or more.

The (meth) acrylate copolymer (A) contains 40% by mass or more of an alkyl group having 1 to 20 carbon atoms of (meth)acrylic acid as a monomer unit constituting the polymer, and preferably contains 50% by mass or more is particularly preferable, and 60% by mass or more is further more preferable. When 40% by mass or more of the alkyl (meth)acrylate is contained, appropriate adhesion can be imparted to the (meth) acrylate copolymer (A). Further, the alkyl (meth)acrylate having 1 to 20 carbon atoms and having an alkyl group of 90% by mass or less is preferably 80% by mass or less, and more preferably 70% by mass or less. By setting the content of the alkyl (meth)acrylate to 90% by mass or less, it is possible to supply (meth) acrylate A desired amount of other monomer component is introduced into the copolymer (A).

The (meth) acrylate copolymer (A) preferably contains a monomer having an alicyclic structure in the molecule (an alicyclic structure-containing monomer) as a monomer unit constituting the copolymer. Since the volume of the alicyclic structure-containing monomer is large, the interval between the polymers is enlarged by the presence of the alicyclic structure-containing monomer in the polymer. As a result, the compound (C) becomes easily moved in the polymer, whereby it becomes easy to be exposed on the surface of the adhesive. Thereby, the action of the compound (C) as a rework preparation can be effectively exhibited, and the reworkability of the obtained adhesive is further excellent.

The carbon ring of the alicyclic structure in the alicyclic structure-containing monomer may be a saturated structure or a partially 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 polycyclic in view of expanding the distance between the obtained (meth) acrylate copolymers (A) and effectively exerting the action of the compound (C) as a rework formulation. An alicyclic structure (multi-ring structure) is preferred. Further, considering the compatibility of the (meth) acrylate copolymer (A) with other components, the above polycyclic structure is particularly preferably bicyclic to tetracyclic. Further, in the same manner as described above, the number of carbon atoms of the alicyclic structure (refer to the number of all carbon atoms forming part of the ring, when there are independent plural numbers) from the viewpoint of effectively exhibiting the action of the compound (C) as a rework formulation In the case of a ring, it means that the total number of carbon atoms is usually 5 or more, preferably 7 or more. On the other hand, the upper limit of the number of carbon atoms 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 cyclohexyl bone. , dicyclopentadiene skeleton, adamantane skeleton, isobornyl skeleton, cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclodecane skeleton, cyclodecane skeleton, cycloundecane skeleton, ring ten a dialkyl skeleton or the like), a cycloolefin skeleton (a cycloheptene skeleton, a cyclooctene skeleton, etc.), a norbornene skeleton, a norbornadiene skeleton, a cubane skeleton, a lanthanane skeleton, an alkane skeleton, a spiro skeleton, or the like Among them, a dicyclopentadiene skeleton (carbon number of alicyclic structure: 10), an adamantane skeleton (carbon number of alicyclic structure: 10) or an isobornyl skeleton The carbon number of the alicyclic structure: 7) is preferred, and the isobornyl group-containing skeleton is particularly preferred.

As the alicyclic structure-containing monomer, a (meth) acrylate monomer having the above skeleton is preferable, and specific examples thereof include cyclohexyl (meth) acrylate and dicyclopentane (meth) acrylate. An ester, an adamantyl (meth)acrylate, an isobornyl (meth)acrylate, a dicyclopentanyl (meth)acrylate, a dicyclopentyloxyethyl (meth)acrylate, etc., among which, it is more excellent. Durable dicyclopentanyl (meth)acrylate, adamantyl (meth)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.

When the (meth) acrylate copolymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, the (meth) acrylate copolymer (A) contains 5% by mass or more of an alicyclic ring. The monomer having a structural unit is preferable, and it is particularly preferably 8% by mass or more, and more preferably 11% by mass or more. Further, the (meth) acrylate copolymer (A) contains 40% by mass or less of an alicyclic structure-containing monomer as a monomer unit constituting the polymer, more preferably 30% by mass or less, and particularly preferably 25% by mass. % below is further preferred. By making the content of the alicyclic structure-containing monomer within the above range, the compound (C) can be effectively exerted as a re-addition The effect of the formulation is that the reworkability of the obtained adhesive is more excellent.

The (meth) acrylate copolymer (A) preferably contains a monomer having a nitrogen atom in the molecule (a monomer containing a nitrogen atom) as a monomer unit constituting the copolymer. By allowing the nitrogen atom-containing monomer to exist as a constituent unit in the polymer, it is possible to promote the reaction of the acrylate copolymer (A) and the crosslinking agent (B), or to impart polarity to the adhesive, and to improve the adhesive itself. Cohesion.

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-vinylisoxazole, 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, monomethylamine (meth)acrylate Ethyl ethyl ester, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, monoethylaminopropyl (meth)acrylate, dimethyl (meth)acrylate Aminoethyl ester and the like.

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

When the (meth) acrylate copolymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the (meth) acrylate copolymer (A) contains 1% by mass or more of a nitrogen atom-containing monomer. More preferably, it is more preferably 2% by mass or more, and further preferably 4% by mass or more. Further, the (meth) acrylate copolymer (A) contains 40% by mass or less of a nitrogen atom-containing monomer as a monomer unit constituting the polymer, more preferably 25% by mass or less, and particularly preferably 14% by mass or less. It is further preferred. If the content of the nitrogen atom-containing monomer is within the above range, the cohesive force of the obtained adhesive is effectively increased.

The (meth) acrylate copolymer (A) may contain other monomers as a monomer unit constituting the polymer, as needed. As the other 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.

As described above, the (meth) acrylate copolymer (A) has a weight average molecular weight of 400,000 or more, more preferably 450,000 or more, and particularly preferably 500,000 or more. If the weight average molecular weight of the (meth) acrylate copolymer (A) is as described above Further, the reworkability of the obtained adhesive and the step followability under high temperature and high humidity conditions can be satisfactorily ensured. Further, as described above, the weight average molecular weight is preferably 1.3 million or less, more preferably 1,000,000 or less, and particularly preferably 900,000 or less. When the weight average molecular weight of the (meth) acrylate copolymer (A) is at most the above, the obtained adhesive exhibits good flexibility and is excellent in initial step difference followability.

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, for example, it is excellent in the step followability even under high temperature and high humidity conditions.

The crosslinking agent (B) may be reacted with a reactive group of the (meth) acrylate copolymer (A), and examples thereof include an isocyanate crosslinking agent and an epoxy crosslinking. Agent, amine crosslinking agent, melamine crosslinking agent, aziridine crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal 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 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) acrylate is preferable. When the reactive group of the 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 contains at least a polyisocyanate compound By. 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 an adduct of a reactant with 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, etc. . Among them, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane is preferred from the viewpoint of reactivity with a carboxyl group.

The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and 0.1 part by mass based on 100 parts by mass of the (meth) acrylate copolymer (A). The above is further preferred. Further, the content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and further preferably 0.4 parts by mass or less. When the content of the crosslinking agent (B) is within the above range, the obtained adhesive exhibits a good cohesive force, and is excellent in step followability under high-temperature and high-humidity conditions.

(3) Compound (C)

The compound (C) is a compound having an alkylene oxide moiety and having no or a reactive group reactive with the crosslinking agent (B). As described above, among the adhesives obtained from the adhesive composition P, the compound (C) functions as an excellent rework preparation. Specifically, the compound (C) is a compound having an alkylene oxide moiety, and the obtained adhesive exhibits excellent reworkability. Further, the compatibility with the (meth) acrylate copolymer (A) is ensured by the fact that the compound (C) does not have or has a reactive group which reacts with the crosslinking agent (B). Further, at the same time, the reaction of the (meth) acrylate copolymer (A) and the crosslinking agent (B) is not inhibited by the compound (C), and a good crosslinked structure can be formed, and the obtained adhesive can be used. The cohesiveness of hope. Further, since the compound having the above structure is different from the surfactant, when the adhesive composition P is prepared, it is difficult to generate bubbles, and even if it is produced, it is easily removed. Therefore, the bubble-free adhesive layer can be easily formed.

It is preferred that the compound (C) has a linear structure. The compound (C) has a linear structure and is easily moved in the (crosslinked structure of) the (meth) acrylate copolymer (A) during the formation of the adhesive layer such as a drying process. As a result, the compound (C) is easily exposed on the surface of the adhesive, and effectively functions as a rework preparation, and the reworkability of the obtained adhesive is further excellent. In addition, in this specification, "linear" of "linear structure" shows a substantially "linear". In other words, the linear structure may have a branch as long as the effect of the compound (C) as a rework preparation can be satisfactorily exhibited.

The compound (C) is not preferably an anthrone compound, that is, a compound having no azepine bond in the molecule is preferred. If the adhesive composition P contains an anthrone compound, the adhesive layer of the obtained adhesive is laminated with the adhesive The interaction between the peeling sheets is strong, and the peeling sheet may be peeled off. Further, the anthrone compound does not function as a rework preparation.

The alkylene oxide at the alkylene oxide moiety is preferably an alkylene oxide having 2 to 4 carbon atoms, and examples thereof include ethylene oxide, propylene oxide, butylene oxide, and the like. Oxyethane is preferred. Further, examples of the reactive group that reacts with the crosslinking agent (B) include a hydroxyl group, a carboxyl group, and an amine group.

The compound (C) has a linear structure, and a non-reactive group which does not react with the crosslinking agent (B) at both ends or one end thereof is preferred. The non-reactive group is preferably an alkyl group or a (meth) acrylonitrile group. That is, the compound (C) has a linear structure, and it is preferred to have an alkyl group at both terminals or one end thereof, or a (meth) acrylonitrile group at both ends or one end thereof. Also, the compound (C) may have a linear structure and have an alkyl group at one terminal and a (meth)acryl fluorenyl group at the other end.

The alkyl group has preferably 1 or more carbon atoms. Further, the alkyl group preferably has 10 or less carbon atoms, and more preferably 5 or less. As the alkyl group, specifically, a methyl group, an ethyl group, a propyl group or the like is preferable, and in particular, a methyl group is preferred from the viewpoint of the polarity of the compound.

The (meth) acrylonitrile group does not react with the crosslinking agent (B) and remains directly in the adhesive. Since the compound (C) has a linear structure and has a (meth)acryl fluorenyl group at both ends or one end thereof, it is more compatible with the (meth) acrylate copolymer (A). The adhesiveness and reworkability of the obtained adhesive can be stably obtained.

From the viewpoint of the reworkability to be exhibited, the compound (C) is preferably a glycol ether skeleton, and among them, it has a monoglycol ether and a diethylene glycol. A skeleton such as an alcohol ether, a triethylene glycol ether, a tetraethylene glycol ether or a polyethylene glycol ether is preferred.

Specific examples of the compound (C) include tetraethylene glycol alkyl ether, tetraethylene glycol dialkyl ether, polyethylene glycol alkyl ether, and polyethylene glycol dialkyl ether. Alkoxy polyethylene glycol (meth) acrylate, polyethylene glycol di (meth) acrylate, and the like. Among the above, tetraethylene glycol dimethyl ether, polyethylene glycol methyl ether, methoxy polyethylene glycol (meth) acrylate, and polyethylene glycol II are considered from the viewpoint of reworkability to be exhibited. (Meth) acrylate is especially preferred. Further, the compound (C) may be used alone or in combination of two or more.

The number average molecular weight of the compound (C) is preferably 100 or more, more preferably 200 or more, and still more preferably 300 or more. Further, the number average molecular weight is preferably 2,000 or less, more preferably 1,500 or less, and still more preferably 1,000 or less. When the number average molecular weight of the compound as the compound (C) is within the above range, the compound (C) becomes easily moved in the (crosslinked structure) of the (meth) acrylate copolymer (A), thereby changing It is easy to be exposed on the surface of the adhesive, and the reworkability of the obtained adhesive is further excellent. Further, the number average molecular weight in the present specification is a standard polystyrene equivalent value measured by a gel permeation chromatography (GPC) method.

The content of the compound (C) in the adhesive composition P is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, and 1.0 part by mass based on 100 parts by mass of the (meth) acrylate copolymer (A). The above is particularly preferable, and 1.5 parts by mass or more is further preferable. When the content of the compound (C) is at least the above, the compound (C) can be effectively used as a rework preparation, and the reworkability of the obtained adhesive is further excellent. Further, the content of the compound (C) is preferably less than 10 parts by mass, particularly preferably 8 parts by mass or less, and 5 parts by mass. The following are further preferred. When the content of the compound (C) is at most the above, the adhesive strength of the adhesive for a display is more 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) An amine group-containing oxime compound such as -aminoethyl)-3-aminopropyltrimethoxydecane or N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane, 3-chloropropyltrimethoxydecane, 3-isocyanatepropyltriethoxydecane, or at least one of these with methyltriethoxydecane, ethyltriethoxydecane, methyltrimethoxydecane A condensate of an alkyl group-containing hydrazine compound such as ethyltrimethoxydecane 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 parts by mass or more, more preferably 0.05 parts by mass or more, and 0.1 part by mass based on 100 parts by mass of the (meth) acrylate copolymer (A). The above is further preferred. Further, the content is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, and further preferably 0.3 part by mass or less.

(5) Various additives

In the adhesive composition P, various additives commonly used for acrylic adhesives such as ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, fillers, and refractive indexes may be added as needed. Adjusting agent, etc. Further, the polymerization solvent and the diluent solvent to be described later are not included in the additive constituting the adhesive composition P.

(6) 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 compound (C). Further, it is produced by adding a decane coupling agent (D) and an additive as needed.

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. As an azo compound, for example Examples thereof include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), and 1,1'-azobis(cyclohexane-1-carbonitrile). 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-hydroxymethylpropanenitrile) , 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.

After obtaining the (meth) acrylate copolymer (A), a crosslinking agent (B), a compound (C), and a decane coupling agent (D) are added as needed in the solution of the (meth) acrylate copolymer (A). The additive, the diluent, and the solvent are thoroughly mixed, whereby an adhesive composition P (coating solution) diluted with a solvent is obtained. However, since the compound (C) used in the present embodiment is different from the surfactant, when the adhesive composition P is prepared, it is difficult to generate bubbles, and even if it is produced, it is easily removed. Therefore, the bubble-free adhesive layer can be easily formed.

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.

[adhesive]

The adhesive of the present embodiment is obtained by crosslinking the adhesive composition P. Crosslinking of the adhesive composition P can usually be carried out by heat treatment. In addition, the heat treatment can also be carried out by a drying process when a coating solvent such as a diluent solvent applied to the adhesive composition P of a desired object is volatilized.

The heating temperature of the heat treatment is preferably from 50 to 150 ° C, particularly preferably from 70 to 120 ° C. Further, the heating time is preferably from 10 seconds to 10 minutes, and particularly preferably from 50 seconds to 2 minutes.

After the heat treatment, if necessary, a aging period of about 1 to 2 weeks may be performed at normal temperature (for example, 23 ° C, 50% RH). When the aging period is required, the adhesive is formed after the aging period, and when the aging 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 via the crosslinking agent (B), and a compound exists in the crosslinked structure and on the surface of the crosslinked structure. (C). The adhesive thus obtained maintains the performance as an adhesive for a display body, and particularly has excellent step followability under high temperature and high humidity conditions and is excellent in reworkability.

The lower limit of the gel fraction of the adhesive of the present embodiment is preferably 30% or more, more preferably 40% or more, and particularly preferably 50% or more. When the lower limit of the gel fraction of the adhesive is at least the above, the cohesive force of the adhesive is improved, and the step followability in the high-temperature and high-humidity conditions is further excellent. Further, the upper limit of the gel fraction of the adhesive of the present embodiment is preferably 90% or less, more preferably 85% or less, and still more preferably 80% or less. When the upper limit of the gel fraction of the adhesive is not more than the above, the adhesive does not become too hard, and the initial step difference is more excellent. The method for measuring the gel fraction of the adhesive is as shown in the test examples described later.

[adhesive sheet]

The adhesive sheet of the present embodiment has an adhesive layer for bonding one display body constituent member and another display body constituent member, and the adhesive layer includes the above-mentioned adhesive.

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 means peeling in a peeling sheet. The surface of the property includes both the surface on which the release treatment is carried out and the surface on which the release property is exhibited even if the release treatment is not performed.

(1) Adhesive layer

The adhesive layer 11 is composed of the above-described adhesive, that is, an adhesive formed by crosslinking the adhesive composition P.

The lower limit of the thickness of the adhesive layer 11 (the value measured according to JIS K7130) in the adhesive sheet 1 of the present embodiment is preferably 20 μm or more, more preferably 25 μm or more, and particularly preferably 30 μm or more, and 50 μm or more is further preferable. good. When the lower limit of the thickness of the adhesive layer 11 is 20 μm or more, the desired adhesive force is easily exhibited. In addition, when the lower limit of the thickness of the adhesive layer 11 is 30 μm or more, it is possible to ensure sufficient step followability with respect to the normal step of the display member.

Further, the thickness of the adhesive layer 11 is preferably 500 μm or less, more preferably 400 μm or less, and particularly preferably 300 μm or less. When the upper limit of the thickness of the adhesive layer 11 is the above or less, the workability is good. Further, the adhesive layer 11 may be formed of a single layer or may be formed by laminating a plurality of layers.

(2) peeling sheet

The release sheets 12a and 12b are used to protect the adhesive layer 11 before the adhesive sheet 1 is used, and are peeled off when the adhesive sheet 1 (adhesive layer 11) 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 Ester film, vinyl acetate film, ionomer resin film, ethylene. (Meth)acrylic copolymer film, ethylene. (Meth) acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, and 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.

(3) Physical properties

(3-1) Step difference follow rate

In the adhesive layer 11 of the pressure-sensitive adhesive sheet 1 of the present embodiment, the lower limit value of the step-span tracking ratio (%) expressed by the following formula is preferably 20% or more, more preferably 25% or more, and further preferably 30% or more. . Further, the upper limit of the step follow rate is not particularly limited, but is usually 80% or less, preferably 70% or less.

The step-span follow rate (%) = { (the height (μm) of the step of the state in which the state is filled without bubbles, floats, peeling, etc. after the endurance test) / (thickness of the adhesive layer)} × 100

In addition, the test method of the step follow rate is as shown in the test example mentioned later.

The adhesive layer of the adhesive sheet of the embodiment is suitable for being attached The surface on one side has a step of the display member constituting the step. When the step follow rate of the adhesive layer is within the above range, the adhesive layer satisfactorily follows the step of the display member constituting member, and after the endurance test, it is possible to suppress generation of bubbles, floating, peeling, and the like in the vicinity of the step. The reflection loss of generated light can be suppressed. Even if the adhesive contains the compound (C), the step follow rate of the above range can be achieved.

(3-2) haze value

The adhesive layer 11 of the adhesive sheet 1 of the present embodiment preferably has a haze value of 5.0% or less, more preferably 3.0% or less, and still more preferably 1.0% or less. When the haze value of the pressure-sensitive adhesive layer 11 is 5.0% or less, the transparency is extremely high, and it is suitable for optical use (for display). In addition, the haze value in this specification is set to the value measured by JIS K7136:2000.

(3-3) Adhesion

The lower limit of the adhesive strength of the adhesive sheet 1 of the present embodiment with respect to the soda lime glass is preferably 1 N/25 mm or more, more preferably 2 N/25 mm or more, and further preferably 5 N/25 mm or more. When the adhesive force of the adhesive sheet 1 is 1 N/25 mm or more, the step-following property under high temperature and high humidity conditions is more excellent. Further, the upper limit of the adhesive force of the adhesive sheet 1 of the present embodiment with respect to the soda lime glass is preferably 35 N/25 mm or less, more preferably 30 N/25 mm or less, and particularly preferably 25 N/25 mm or less. When the adhesive force of the adhesive sheet 1 is 35 N/25 mm or less, reworkability can be excellent. Thereby, even when the bonding failure of the member constituting the display body occurs, the adhesive layer can be easily peeled off from the display body constituting member, and the expensive display body constituting member can be reused.

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

(3-4) Peel force

When the adhesive layer 11 (the laminate of the base material and the adhesive layer 11) of the present embodiment is peeled off from the release sheet 12a or 12b, the lower limit of the peeling force is preferably 30 mN/25 mm or more, more preferably 50 mN/25 mm or more. More preferably, 80 mN/25 mm or more. When the peeling force is 30 mN/25 mm or more, accidental peeling of the release sheet 12a or 12b from the adhesive layer 11 can be suppressed. Further, when the adhesive layer 11 (the laminate of the base material and the adhesive layer 11) of the present embodiment is peeled off from the release sheet 12a or 12b, the upper limit of the peeling force is preferably 300 mN/25 mm or less, and preferably 200 mN/25 mm or less. Better, especially below 150mN/25mm. When the peeling force is 150 mN/25 mm or less, the release sheet 12a or 12b can be easily peeled off from the adhesive layer 11.

Here, the peeling force in the present specification basically means an adhesive force measured by a 180-degree peeling method according to JIS Z0237:2009, specifically, as shown in a test example described later.

(4) 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 the aging period is required, the above coating layer becomes the adhesive layer 11 by the aging period, when When the aging period is not required, the coating layer directly becomes the adhesive layer 11. Thereby, the above-mentioned adhesive sheet 1 can be obtained. The heat treatment and ripening 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 the aging period is required, the coating layer of the above-mentioned laminated layer becomes the adhesive layer 11 through the aging period, and when the aging period is not required, the coating layer of the above-mentioned laminated layer directly becomes the adhesive layer 11. Thereby, the above-mentioned adhesive sheet 1 can be obtained. 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 a first display body constituent member 21 (a display body constituent member) and a second display body constituent member 22 (another display body constituent member); The adhesive layer 11 which is located between the first display body constituent member 21 and the second display body constituent member 22 is bonded to each other.

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

It is preferable that the first display body constituent member 21 and the second display body constituent member 22 are hard bodies. The bonding of the hard bodies of the adhesive layer is more difficult than the bonding of the films or the film to the hard body, and the yield at the time of bonding is likely to be lowered. Therefore, in this case, it is necessary to peel off the two hard bodies so that the first display body constituent member 21 and/or the second display body constituent member 22 (especially an expensive display body module) can be reused. However, when a usual adhesive layer is used, it is difficult to peel off two hard bodies. On the other hand, by using the adhesive layer 11 of the adhesive sheet 1 of the present embodiment, the two hard bodies can be easily peeled off, and the first display member constituent member 21 and/or the second display member constituent member 22 can be realized. use.

In addition, the term "hard body" in the present specification means that the modulus of elasticity measured according to JIS K7127:1999 is 10 GPa or more. The hard body may be a single layer or a single member, or may be a plurality of layers or a plurality of members. In the latter case, as an object including a plurality of layers or a plurality of members, the article can be referred to as a hard body even if a part of the layer or member of the article does not satisfy the above elastic modulus as long as the above elastic modulus is satisfied.

It is preferable that the first display body constituent member 21 (one display body constituent member) has a step at least on the surface on which one side is bonded. 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 difference based on the printed layer 3. The adhesive layer 11 of the adhesive sheet 1 of the present embodiment is excellent in step followability (initial step followability and step followability under high temperature and high humidity conditions), and thus the adhesive sheet 1 is attached to the first display constituent member 21 When the adhesive layer 11 is easy to follow the step, it can be suppressed in the step A gap, a float, and the like are generated in the vicinity. Further, when placed in a high temperature and high humidity condition in this state, it is possible to suppress generation of bubbles, floating, peeling, and the like in the vicinity of the step.

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 panel including a laminate or the like. 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, and yttrium. Neodymium glass, aluminosilicate glass, lead glass, 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 (for example, a liquid crystal (LCD) module to be attached to the first display body constituent member 21; A group, a light-emitting diode (LED) module, an organic electroluminescence (organic EL) module, or the like, an optical member as a part of the display body module, or a laminate including a display body module is preferable.

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 lower limit of the height of the step is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 7 μm or more, and most preferably 10 μm or more. By the lower limit value being the above or more, it is possible to sufficiently ensure that the concealability such as the electric wiring is not visible from the observer side. Further, the upper limit is preferably 50 μm or less, more preferably 35 μm or less, particularly preferably 25 μm or less, and further preferably 20 μm or less. By the upper limit being the above or lower, it is possible to prevent deterioration of the step followability of the adhesive layer 11 with respect to the printed layer 3.

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 is possible to suppress occurrence of a gap or floating in the vicinity of the step formed by the printed layer 3.

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 and the second display body are formed. The member 22 is bonded to obtain the display body 2. Further, as another example, the order of bonding the first display body constituent member 21 and the second display body constituent member 22 may be replaced. 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.

In the display body 2 as described above, the adhesive layer 11 is excellent in step followability under high temperature and high humidity conditions. Therefore, when the display body 2 is placed under high temperature and high humidity conditions (for example, 85 ° C, 85% RH), It is suppressed that bubbles, floating, peeling, and the like are generated in the vicinity of the step.

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 present invention is not limited to the examples and the like.

[Example 1]

1. Preparation of (meth) acrylate copolymer

(Meth) acrylate copolymerization by copolymerizing 60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of isobornyl acrylate, 5 parts by mass of N-propenylmorpholine and 15 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 Soken Chemical & Engineering Co., Ltd., product name "L-45") 0.2 parts by mass of tetraethylene glycol dimethyl ether as compound (C) (manufactured by TOHO Chemical Industry Co., Ltd., product name " Haisorubu MTEM") 0.5 parts by mass of 0.2 parts by weight of 3-glycidoxypropyltrimethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM403") as a decane coupling agent (D) The mixture 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 45% 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.

Next, the coating layer on the heavy release type release sheet obtained above and the anthrone-based release agent to polyethylene terephthalate are bonded to the release-treated surface of the light release-type release sheet in contact with the coating layer. The light-peelable release sheet (manufactured by LINTEC Corporation, product name "SP-PET382120") which was subjected to a release treatment on one side of the ester film, was aged at 23 ° C and 50% RH for 7 days, thereby having a thickness. An adhesive sheet of a 25 μm adhesive layer, that is, an adhesive sheet (first adhesive sheet) comprising a structure of a heavy release type release sheet/adhesive layer (thickness: 25 μm) / a light release type release sheet. In addition, the adhesion of the adhesive layer having a thickness of 50 μm was produced in the same manner as described above except that the solid content concentration of the coating solution of the adhesive composition was changed to 55 mass%, and the thickness of the pressure-sensitive adhesive layer was changed to 50 μm. A sheet, that is, an adhesive sheet (second adhesive sheet) comprising a structure of a heavy release type release sheet/adhesive layer (thickness: 50 μm) / a light release type release sheet. Further, the thickness of the adhesive layer is a value measured in accordance with JIS K7130 and using a constant pressure thickness measuring instrument (manufactured by TECLOCK Corporation, product name "PG-02").

Here, Table 1 shows the respective components (solid content conversion values) of the adhesive composition when the (meth) acrylate copolymer (A) is 100 parts by mass (solid content conversion value). In addition, the details of the abbreviations and the like described in Table 1 are as follows.

[(Meth)acrylate copolymer (A)]

2EHA: 2-ethylhexyl acrylate

IBXA: Isobornyl acrylate

ACMO: N-propylene hydrazine

HEA: 2-hydroxyethyl acrylate

MMA: Methyl methacrylate

BA: n-butyl acrylate

MA: Methyl acrylate

AA: Acrylic

[Crosslinking agent (B)]

TDI: Trimethylolpropane modified toluene diisocyanate (manufactured by Soken Chemical & Engineering Co., Ltd., product name "L-45")

XDI: Trimethylolpropane modified xylene diisocyanate (manufactured by Soken Chemical & Engineering Co., Ltd., product name "TD-75")

Epoxy: 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC., product name "TETRAD-C")

[Compound (C)]

Haisorubu MTEM: Tetraethylene glycol dimethyl ether (manufactured by TOHO Chemical Industry Co., Ltd., product name "Haisorubu MTEM")

PEGME: polyethylene glycol methyl ether (manufactured by ALDRICH, number average molecular weight 550)

A-400: polyethylene glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-400", number average molecular weight 400)

M-130G: methoxy polyethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "M-130G", number average molecular weight 550)

KF6000: Reactive eucalyptus oil Methanol modification at both ends (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KF6000")

KF2012: Reactive eucalyptus oil One end methacrylic acid modification (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KF2012")

KF8010: Reactive eucalyptus oil Modified at both ends (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KF8010")

PEG (1000): polyethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., number average molecular weight: 1000)

[Examples 2 to 22, Comparative Examples 1 to 5]

The type and ratio of each monomer constituting the (meth) acrylate copolymer (A), the weight average molecular weight (Mw) of the (meth) acrylate copolymer (A), and the type of the crosslinking agent (B) The adhesive sheet (first adhesive sheet and the first adhesive sheet) was produced in the same manner as in Example 1 except that the blending amount, the type and amount of the compound (C), and the blending amount of the decane coupling agent (D) were changed as shown in Table 1. 2 sticky sheets).

[Test Example 1] (Evaluation of defoaming property)

The coating solution of the adhesive composition prepared in the examples and the comparative examples was stirred at room temperature for 15 minutes at 1500 rpm using a high-speed disperser (manufactured by PRIMIX Corporation, product name "HOMOGENIZING DISPER 2.5 type"). Subsequently, a desiccant was defoamed under reduced pressure for 20 minutes using a dryer (manufactured by AS ONE Corporation., product name "stainless steel vacuum dryer DVS-310") at a normal temperature at a vacuum gauge of -0.06 MPa. The coating solution in this state was visually confirmed, and it was judged that the bubble removal was good (○), and the bubble was not removed (x). The results are shown in Table 2.

[Test Example 2] (Measurement of gel fraction)

The adhesive sheet (first adhesive sheet) obtained in the examples and the comparative examples was cut into a size of 80 mm × 80 mm, and the adhesive layer was wrapped in a polyester mesh (mesh size 200) by a precision balance scale. Take the quality and subtract the individual mass of the above net to calculate the quality of the adhesive itself. 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.

[Test Example 3] (Measurement of haze value)

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

[Test Example 4] (Measurement of adhesion)

The light release type release sheet was peeled off from the adhesive sheets (first adhesive sheet and second adhesive sheet) obtained in the examples and the comparative examples, and the exposed adhesive layer was attached to the polyphenylene terephthalate having an easy adhesion layer. A layer of a release film/adhesive layer/PET film was obtained by using an ethylene glycol formate (PET) film (manufactured by TOYOBO CO., LTD., product name "PET A4300", thickness: 100 μm). 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 (manufactured by Corning Incorporated, product name "Eagle XG"). The autoclave made by Kurihara Manufactory Inc. was pressurized at 0.5 MPa and 50 ° C for 20 minutes. Thereafter, it was left at 23 ° C and 50% RH for 24 hours. After that, the adhesive force (N/25 mm) was measured under the conditions of a peeling speed of 300 mm/min and a peeling angle of 180 degrees using a universal tensile tester (manufactured by ORIENTEC Co., LTD., product name "Tensilon UTM-4-100"). . Conditions other than those described herein were measured in accordance with JIS Z 0237:2009. The results are shown in Table 2.

[Test Example 5] (Measurement of peeling force)

With respect to the adhesive sheet (first adhesive sheet) obtained in the examples and the comparative examples, samples were prepared in the same manner as in Test Example 3. The release sheet side of the sample was attached to a stainless steel plate using a double-sided tape, and fixed to a universal tensile tester (manufactured by ORIENTEC Co., LTD., product name "Tensilon UTM-4-100"). The PET film of the sample was stretched at a tensile speed of 300 mm/min in the 180° direction under the conditions of a temperature of 23° C. and 50% RH according to JIS Z 0237:2009, and the laminate of the PET film and the adhesive layer was peeled off from the release sheet. The force at the time of body is taken as the peeling force (mN/25 mm). The results are shown in Table 2.

[Test Example 6] (Evaluation based on reworkability of residual glue)

The adhesion of the test example 3 was measured, and the adhesive sheet (first adhesive sheet) as a sample was peeled off, and then the area of the residue in the surface of the alkali-free glass (adhesive surface of the adhesive) was measured. The reworkability (normal temperature) was evaluated on the basis of the following criteria. The results are shown in Table 2.

○... There is no residue at all.

△... There is a residue which is less than 30% of the area of the bonding area.

×... Residues having an area of 30% or more of the bonded area.

Further, as shown in Test Example 3, the adhesive sheet (first adhesive sheet) as a sample was bonded to an alkali-free glass, and after pressurization, it was allowed to stand under conditions of 23 ° C and 50% RH for 24 hours, and then, at 60 ° Placed under °C, 90% RH 24 hours (promotional conditions). Thereafter, the adhesive sheet (first adhesive sheet) was peeled off by the method shown in Test Example 3, and the reworkability (after the promotion condition) was evaluated based on the above criteria. The results are shown in Table 2.

[Test Example 7] (Measurement of step difference rate)

Surface-printing UV-curable ink in a glass plate (manufactured by NSG Precision Co., Ltd., product name "Corning Glass EAGLE XG", vertical 90 mm × width 50 mm × thickness 0.5 mm) (Teikoku Printing Inks Mfg. Co., Ltd. The product name "POS-911 ink" was used to make the coating thickness into a frame shape of any of 5 μm, 10 μm, 15 μm, and 20 μm (outer shape: vertical 90 mm × width 50 mm, width 5 mm). 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 film formed by printing. A glass plate with a step difference (the height of the step: any one of 5 μm, 10 μm, 15 μm, and 20 μm).

The light-peelable release sheet was peeled off from the second adhesive sheet (thickness of the adhesive layer: 50 μm) obtained in the examples and the comparative examples, and the exposed adhesive layer was attached to the poly(p-phenylene) having an easy-adhesion layer. Ethylene formate film (manufactured by TOYOBO Co., Ltd., product name "PET A4300", thickness: 100 μm). Next, the heavy release type release sheet was peeled off, and the adhesive layer was peeled off. Thereafter, the laminated body was molded to a glass plate with a stepped surface by using a laminator (manufactured by FUJIPLA Inc., product name "LPD3214") so as to cover the entire printing surface of the frame with an adhesive layer, and this was used as an evaluation. sample.

The obtained sample for evaluation was subjected to an autoclave treatment at 50 ° C and 0.5 MPa for 30 minutes, and then left under normal pressure at 23 ° C and 50% RH for 24 hours. Then, under the high temperature and high humidity conditions of 85 ° C and 85% RH Tubes were for 72 hours (endurance test), after which the step followability was evaluated. The step followability is judged by whether or not the printing step difference is completely filled by the adhesive layer, and when bubbles, floating, peeling, and the like are observed at the interface between the printing step and the adhesive layer, it is judged that the printing step is not followed. Here, the step followability is evaluated as a step follow rate (%) expressed by the following expression. The results are shown in Table 2.

Step follow rate (%) = {(the height (μm) of the step of the state in which the state is filled without bubbles, floats, peeling, etc. after the endurance test) / (thickness of the adhesive layer: 50 μm)} × 100

As is apparent from Table 2, the adhesive sheet obtained in the examples had an appropriate adhesive force and had less residual glue when peeled off from the adherend, and thus was excellent in reworkability. Further, the adhesive sheet obtained in the examples has a sufficient peeling force, and the step followability (under high temperature and high humidity conditions) is also excellent.

[Industrial availability]

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

1‧‧‧Adhesive film

11‧‧‧Adhesive layer

12a‧‧‧ peeling film

12b‧‧‧ peeling film

Claims (12)

An adhesive composition for forming an adhesive layer which is bonded to a display body constituent member and another display body constituent member, and is characterized by comprising: (meth) acrylate copolymer (A); a crosslinking agent ( B); and the compound (C), the (meth) acrylate copolymer (A) contains a reactive group-containing monomer having a reactive group reactive with the crosslinking agent (B) in the molecule as a constituent of the polymerization a monomer unit having a weight average molecular weight of 400,000 or more and 1.3 million or less, wherein the compound (C) has an alkylene oxide moiety and does not have or has a reactive group which reacts with the crosslinking agent (B). . The adhesive composition according to claim 1, wherein the compound (C) has a linear structure and has an alkyl group at both ends or at one end thereof. The adhesive composition according to claim 1, wherein the compound (C) has a linear structure and has a (meth)acryl fluorenyl group at both ends or at one end thereof. The adhesive composition according to claim 1, wherein the compound (C) is contained in an amount of 0.2 part by mass or more and less than 10 parts by mass based on 100 parts by mass of the (meth) acrylate copolymer (A). . The adhesive composition according to claim 1, wherein the (meth) acrylate copolymer (A) contains an alicyclic structure-containing monomer as a constituent a monomer unit of the polymer. The adhesive composition according to claim 1, wherein the one display body constituent member and the other display body constituent member are hard bodies. The adhesive composition according to claim 1, wherein the one display body constituent member has a step at least on a surface on which one side is attached. An adhesive agent obtained by crosslinking an adhesive composition according to any one of claims 1 to 7. An adhesive sheet comprising an adhesive layer for bonding a display body constituent member and another display body constituent member, wherein the adhesive layer comprises the adhesive according to claim 8 of the patent application. The adhesive sheet according to claim 9, wherein the thickness of the adhesive layer is 20 μm or more and 500 μm or less. The adhesive sheet according to claim 9, 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 release faces of the two release sheets. A display body comprising: a display body constituting member; another display body constituting member; and an adhesive layer which is bonded to the display body constituting member and the other display body constituting member, and is characterized in that: the adhesive The layer is the adhesive of the adhesive sheet described in claim 9 Agent layer.