KR20170078510A - Adhesive composition, adhesive film and image display device - Google Patents

Abstract

[PROBLEMS] To provide a pressure-sensitive adhesive composition which does not peel or peel off even under bending operation under two conditions of high temperature and low temperature.
The main component (A) comprises a main component (A) comprising a curable compound, a crosslinking agent (B) and a photopolymerization initiator (C) (A) a combination of (a-1) a combination of a (meth) acrylic monomer (a-1-b) (A-2) comprising a structural unit (2) derived from a (meth) acrylic monomer containing a hydroxyl group and a structural unit (a-1-b) ) And a compound represented by the formula (6), wherein the glass transition temperature after curing is lower than -57.0 占 폚.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pressure-sensitive adhesive composition,

The present invention relates to a pressure-sensitive adhesive composition suitable for use in a flexible device, a pressure-sensitive adhesive film for a display made by curing the pressure-sensitive adhesive composition, and an image display device including the same. More specifically, the present invention relates to a pressure-sensitive adhesive composition for an optical film, a pressure-sensitive adhesive film for an optical film obtained by curing the pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet for display (a pressure- The present invention relates to a pressure-sensitive adhesive composition which does not peel or peel off even if a bending operation of deforming a bonded optical film under the respective durability test conditions is performed on the obtained laminate. INDUSTRIAL APPLICABILITY The pressure-sensitive adhesive composition of the present invention is suitably used for lamination of a thin layer adherend including an optical film or sheet, and is also useful for various films or sheets used for a liquid crystal display element such as a flexible display, an electroluminescence element, And can be used in these technical fields.

At present, flat panel display panels such as liquid crystal display panel (LCD) and plasma display panel (PDP) are mainly used as display panels. On the surface of the planar display panel, a laminate in which a plurality of films are stacked is usually bonded. For example, in an LCD, an optical film such as a polarizing plate, a retardation plate, a viewing angle enlarging film, and a brightness improving film is laminated on the surface of a liquid crystal panel. Each layer constituting the planar display panel is usually bonded by an adhesive film formed of various kinds of pressure-sensitive adhesives.

On the other hand, in recent years, in addition to the planar display, a flexible display including a curved display has been developed from the viewpoints of design characteristics, a variety of usage methods, and the like, and flexibility is demanded in the display panel. Organic electroluminescence panels (OLED) are mainly used for flexible displays such as curved displays.

In the optical film laminate laminated by the optical film and the adhesive film or the adhesive film used for the flexible display such as the curved surface display, in addition to the optical characteristics and durability required in the conventional planar display panel, It is required that there is no occurrence of peeling or lifting even if the bending operation for deforming is performed.

As an adhesive film used in a conventional optical film laminate for a planar display panel, Patent Document 1 proposes a pressure-sensitive adhesive sheet obtained by crosslinking a pressure-sensitive adhesive composition containing an acrylate ester polymer, an acrylic crosslinking monomer and a crosslinking initiator have. Patent Document 2 proposes a photopolymerizable pressure-sensitive adhesive composition containing an acrylic syrup containing an alkoxyalkyl (meth) acrylate monomer, a monomer having two or more polymerizable unsaturated groups, a crosslinking agent and a photopolymerization initiator. Patent Document 3 proposes a pressure-sensitive adhesive composition for an optical member containing a base polymer and lactone-modified tris [(meth) acryloxyalkyl] isocyanurate. Patent Document 4 proposes an optical resin composition containing an acrylic acid-based derivative, an acrylic acid-based derivative polymer and a crosslinking agent.

<Prior Art Literature>

<Patent Literature>

(Patent Document 1) JP2014-025073A

(Patent Document 2) JP2007-161909 A

(Patent Document 3) JP 2011-225704 A

(Patent Document 4) JP2010-1449A

Flexible displays, such as organic electroluminescence panels (OLEDs), are expected to be used in a variety of environments, so that their durability in use in a wide range of temperatures, as well as folding resistance (flex resistance) under both high and low temperature conditions, . However, in the pressure-sensitive adhesive described in Patent Document 1, when the pressure-sensitive adhesive is used for the pressure-sensitive adhesive film of a flexible display due to the crosslinking structure of the acrylic crosslinking monomer, the pressure- Peeling occurs in the bending operation. The pressure-sensitive adhesive described in Patent Document 2 can not satisfy the folding test under two conditions of high temperature and low temperature, and peeling and lifting occur. The pressure-sensitive adhesive described in Patent Documents 3 and 4 can not satisfy the folding test under two conditions of high temperature and low temperature, resulting in peeling and lifting, and also a problem that the durability at the time of bending can not be satisfied.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a pressure-sensitive adhesive composition which can effectively suppress or prevent peeling or peeling from occurring even under a bending operation under two conditions of high temperature and low temperature.

The inventors of the present invention conducted intensive studies in order to solve the above problems. As a result, the inventors of the present invention have found that when a main component (A) comprising a curable compound containing a predetermined acrylic compound, a predetermined crosslinking agent (B) and a photopolymerization initiator And the glass transition temperature after curing is less than -57.0 DEG C, and found that the present invention has been accomplished.

INDUSTRIAL APPLICABILITY According to the present invention, excellent adhesion to an optical film and the like, and peeling and peeling are not caused even under bending operation under two conditions of high temperature and low temperature for a bonded film in various durability test conditions, It is possible to provide a pressure-sensitive adhesive composition which is excellent in folding resistance under two conditions of low temperature. The pressure-sensitive adhesive composition according to the present invention is particularly suitable for flexible display applications.

1 is a sectional view and a plan view of a specimen for measuring shear deformation.
2 is a graph for calculating the shear strain.

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments.

In this specification, unless otherwise stated, the measurement of operation and physical properties is performed under the conditions of room temperature (20 ° C or more and 25 ° C or less) / relative humidity of 40% RH (relative humidity) or more and 50% RH or less.

[Pressure sensitive adhesive composition]

One aspect of the present invention includes a main component (A) comprising a curable compound, a crosslinking agent (B) and a photopolymerization initiator (C), wherein the main component (A) is a (meth) acrylic acid ester monomer (a- (A-1) comprising a hydroxyl group-containing (meth) acrylic monomer (a-1-b); (1) derived from the (meth) acrylic ester monomer (a-1-a) and the structural unit (2) derived from the hydroxyl group-containing (meth) acrylic monomer (a-1-b) Wherein the crosslinking agent (B) comprises at least one of a copolymer (structural unit) represented by the following formula (5) and a compound (structural unit) represented by the following formula (6) (Copolymer), and the pressure-sensitive adhesive composition is a pressure-sensitive adhesive composition having a glass transition temperature after curing of less than -57.0 占 폚.

Wherein R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms, R ₃ is a hydrogen atom or a methyl group, m is 0 or 1, 1, n is an integer of 1 or more and 5 or less, and m is 0 when R ₂ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms.

Wherein R ₄ is a hydrogen atom or a methyl group, R ₅ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms, R ₆ is a hydrogen atom or a methyl group, m is 0 or 1, 1, n is an integer of 1 or more and 5 or less, and m is 0 when R ₅ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms.

INDUSTRIAL APPLICABILITY According to the present invention, excellent adhesion to an optical film and the like, and peeling and peeling are not caused even under bending operation under two conditions of high temperature and low temperature for a bonded film in various durability test conditions, It is possible to provide a pressure-sensitive adhesive composition which is excellent in folding resistance under two conditions of low temperature.

For some reason, the details of how the above-mentioned effects are obtained by the pressure-sensitive adhesive composition of the present invention are unclear, but they are considered as follows. That is, when the pressure-sensitive adhesive composition has an excessively high glass transition temperature (-57.0 DEG C or higher) after curing, sufficient flexibility is not obtained in the cured product of the pressure-sensitive adhesive composition at a low temperature (for example, -20 DEG C) It becomes difficult to obtain immunity. On the other hand, the present inventors have found that (meth) acrylic acid ester monomer (a-1-a) (or copolymer (a-2) containing a constituent unit derived therefrom having a low glass transition temperature of homopolymer) (For example, 80 占 폚) and a low temperature (for example, 80 占 폚) by controlling the glass transition temperature of the pressure-sensitive adhesive composition after curing to less than -57.0 占 폚 by using the curable compound containing the curing compound as the main component -20 &lt; 0 &gt; C).

The reason for this is unclear, but it is not clear whether the main component (A) comprising a curable compound containing a predetermined acrylic compound is combined with the specific crosslinking agent (B) and the photopolymerization initiator (C), and the glass transition temperature after curing of the pressure- The inventors of the present invention have found that the folding resistance can be improved. This is because, by adding a specific crosslinking agent (B), a crosslinked structure is formed in the pressure-sensitive adhesive composition (cured product), and the modulus of the cured product of the pressure-sensitive adhesive composition at high temperature can be improved without deteriorating the flexibility at low temperature. There has been a problem such that the adhesiveness is deteriorated according to the application. In the pressure-sensitive adhesive composition of the present invention, the main component (A) comprising a curable compound containing a predetermined acrylic compound capable of lowering the glass transition temperature after the curing of the pressure-sensitive adhesive composition as described above to a specific crosslinking agent (B) and a photopolymerization initiator C), it is considered that the folding resistance at high temperature and low temperature can be improved by the molecular structure of the specific crosslinking agent (B). (For example, 80 占 폚) and at a low temperature (for example, -20 占 폚) due to the combination with the molecular structure of the specific crosslinking agent (B).

In the pressure-sensitive adhesive composition of the present invention, it is preferable that the pressure-sensitive adhesive composition of the present invention contains a hydroxyl group-containing (meth) acrylic monomer (a-1-b) (or a copolymer (a- It is necessary to use a curable compound as the main component (A). By adopting such a constitution, it is considered that adhesion and durability can be ensured by the high polarity of the hydroxyl group-containing (meth) acrylic monomer (a-1-b). It is considered that the folding resistance can be improved by the hydroxyl group-containing (meth) acrylic monomer (a-1-b) (or the copolymer (a-2) containing the constituent unit derived therefrom).

In addition, the above mechanism is based on speculation, and the present invention is not limited to this mechanism.

The glass transition temperature (Tg) of the pressure-sensitive adhesive composition of the present invention after curing may be less than -57.0 DEG C, but is preferably -57.5 DEG C or lower and -59.0 DEG C or lower from the viewpoint of folding resistance at low temperatures. The lower limit of the glass transition temperature (Tg) after curing of the pressure-sensitive adhesive composition is not particularly limited, and is included in the technical scope of the present invention when the effect of the present invention can be effectively exhibited. The glass transition temperature of the pressure-sensitive adhesive composition after curing can be determined by the method described in Examples. In order to keep the glass transition temperature after curing of the pressure-sensitive adhesive composition within the above-mentioned range, a monomer to be used for preparing the main component (A) may be suitably selected in consideration of the glass transition temperature of the homopolymer. (Meth) acrylic acid ester monomer (a-1) having a low glass transition temperature of the homopolymer and a monomer having relatively high glass transition temperature (for example, a hydroxyl group-containing (meth) acrylic monomer (a- (A ') copolymerizable with the (a-1) component and the (a-1-b) component may be suitably adjusted. Preferably, the lower limit of the glass transition temperature (Tg) of the pressure-sensitive adhesive composition of the invention after curing is -80 캜, more preferably -70 캜. Within the above range, peeling or peeling does not occur even when the pressure-sensitive adhesive film is subjected to a bending operation at a low temperature and at a high temperature, and the folding resistance under two conditions of high temperature and low temperature is excellent.

The pressure-sensitive adhesive composition of the present invention preferably has a storage elastic modulus G '(80) of 2.0 x 10 ⁴ Pa or more at 80 캜 of the pressure-sensitive adhesive composition after curing from the viewpoint of bending resistance at high temperatures. The upper limit of the storage elastic modulus G '(80) is not particularly limited and is included in the technical scope of the present invention when the effect of the present invention can be effectively exhibited. Preferably, the upper limit of the storage elastic modulus G '(80) of the pressure-sensitive adhesive composition after curing at 80 캜 is 4.0 x 10 ⁴ Pa, more preferably 3.5 x 10 ⁴ Pa and 3.0 x 10 ⁴ Pa. Within this range, the bending resistance at high temperatures may be good.

The pressure-sensitive adhesive composition of the present invention preferably has a storage elastic modulus G '(-20) at -20 캜 of not more than 3.5 x 10 ⁵ Pa or less, preferably 2.6 x 10 ⁵ Pa or less in view of the flexural resistance at low temperatures, Pa or lower, 2.55 x 10 ⁵ Pa or lower, and 2.5 x 10 ⁵ Pa or lower. The lower limit of the storage elastic modulus G '(-20) is not particularly limited, and is included in the technical scope of the present invention when the effect of the present invention can be effectively exhibited. Preferably, the lower limit of the storage elastic modulus G '(-20) of the pressure-sensitive adhesive composition after curing at -20 캜 is 0.8 x 10 ⁵ Pa, more preferably 0.85 x 10 ⁵ Pa. Within this range, bending resistance at low temperatures may be good.

The values of the storage moduli G '(80) and G' (- 20) measured by the methods described in the examples are employed. The storage moduli G '(80) and G' (- 20) can be controlled by the composition of the main component (A) or the like.

In the pressure-sensitive adhesive composition of the present invention, the shear deformation under 90 kPa shear stress after curing is preferably 800% or more, more preferably 850% or more, More preferably 900% or more, and still more preferably 1000% or more. If it is within this range, it is excellent in bending resistance. The shear strain is measured by the method described in the embodiment. The shear strain is determined by the composition of the main component (A), the composition of the copolymer (a-2) which can be contained in the main component (A), the kind and amount of the crosslinking agent (B) (also the photopolymerization initiator The type and amount of the silane coupling agent to be added as needed, and the like. The upper limit of the shear deformation is not particularly limited and is included in the technical scope of the present invention when the effect of the present invention can be effectively exhibited. The upper limit of the shear strain under the 90 kPa shear stress after curing is 2000%, preferably 1900%, 1800%, 1700%, 1600%, 1500%, 1300%. In the above range, cracking of the display element and peeling of the adhesive layer when the display is bent can be prevented.

The gel fraction of the pressure-sensitive adhesive composition of the present invention is preferably from 50% to 90%, more preferably from 50% to 85%, further preferably from 50% to 80%, further preferably from 50% to 77% Or more and 70% or less. With such a range, punching or slit processing can be performed quickly as an optical member having an adhesive film. The gel fraction of the pressure-sensitive adhesive composition is a value measured by the method described in the examples. In order to set the gel fraction as described above, the conditions may be appropriately selected, for example, the addition amount of each component is adjusted to the above range.

In the pressure-sensitive adhesive composition of the present invention, the adhesive force of the cured pressure-sensitive adhesive composition (pressure-sensitive adhesive film) to the corona-treated PET film is preferably 450 g / 25 mm or more, more preferably 750 g / 25 mm or more, more preferably 800 g / desirable. With such a range, an excellent adhesive force can be exhibited with respect to an optical film and the like. The adhesive force of the pressure-sensitive adhesive composition (pressure-sensitive adhesive film) after curing is a value measured by the method described in the examples. In order to set the adhesive force of the pressure-sensitive adhesive composition (pressure-sensitive adhesive film) as described above, the conditions may be suitably selected, such as adjusting the amount of each component added to the above range. The upper limit of the adhesive strength is not particularly limited and is included in the technical scope of the present invention when the effect of the present invention can be effectively exhibited. The upper limit of the adhesive force of the pressure-sensitive adhesive composition (pressure-sensitive adhesive film) after curing is preferably 4,000 g / 25 mm.

Hereinafter, each component of the pressure-sensitive adhesive composition of the present invention will be described in detail.

In the present specification, the term "(meth) acrylic acid ester monomer" is a collective term for an acrylic acid ester monomer and a methacrylic acid ester monomer. (Meth) acrylic acid (meth) acrylic acid and the like are also collectively referred to as a compound having "meta" and a compound having no "meta" in the name. For this reason, the term &quot; (meth) acrylic &quot; includes both acrylic and methacrylic. The "(meth) acrylic acid ester monomer" includes both an acrylic acid ester monomer and a methacrylic acid ester monomer. The term "(meth) acrylic acid" includes both acrylic acid and methacrylic acid.

In the present specification, the "pressure-sensitive adhesive composition" is also simply referred to as "pressure-sensitive adhesive". In the present specification, the term "(co) polymer" is a generic term of "polymer (homopolymer)" and "copolymer".

[Main component (A)]

The main component (A) used in the present invention is composed of a curable compound. In the present invention, the (meth) acrylic ester monomer (a-1-a) (hereinafter also simply referred to as the "(a-1-a) component") and the hydroxyl group- (A-1) of (meth) acrylic monomer (a-1-b) (hereinafter also simply referred to as "component (a-1-b)"); (1) derived from the (meth) acrylic ester monomer (a-1-a) and the structural unit (2) derived from the hydroxyl group-containing (meth) acrylic monomer (a-1-b) (A-2) which contains the copolymer (a-2). (A) containing a constituent unit (1) derived from a component (a-1-a) having a low glass transition temperature and / or a component (a- It is possible to lower the glass transition temperature of the pressure-sensitive adhesive composition after curing to less than -57.0 占 폚. Further, by containing the main component (A) in the copolymer (a-2) comprising the constituent unit (2) derived from the component (a-1-b) , High polarity polarizing plate, and the like can be secured. As the curable compound contained in the main component (A), an active energy ray-curable monomer such as a (meth) acrylic compound and its (co) polymer, a (meth) acryloyl group, a vinyl group, an allyl group, A polyester resin, a polyether resin, a polyurethane resin or an epoxy resin containing a polymerizable functional group such as a dithiocarbamate group, a diazo group, a cinnamylidene group and / or a cinnamoyl group, and combinations thereof .

The viscosity of the main component (A) is preferably from 500 mPa s to 5000 mPa 25 at 25 캜, more preferably from 1000 mPa s to 4500 mPa s, and from 1000 mPa ㆍ to 2500 mPa ㆍ, from the viewpoint of coatability and adhesiveness of the pressure- s and not more than 2000 mPa s. The viscosity is a value measured by the method described in the embodiment.

As a preferred form of the main component (A) comprising the curable compound according to the present invention,

(1) A mixture of (a-1-a) and (a-1-b)

(2) a component (a-1-a); (a-1-b) component; And a copolymer (a-2) comprising a constitutional unit (1) derived from the component (a-1-a) and a constitutional unit (2) derived from the component (a- -2)) (a form in which the curable compound is composed of a monomer and a polymer, in the form of a so-called polymer syrup)

(3) a form of the copolymer (a-2) (a form in which the curable compound is composed only of a polymer).

It is considered that this main component (A) is contained in the pressure-sensitive adhesive composition of the present invention, thereby securing the adhesiveness of the pressure-sensitive adhesive film obtained after curing and securing the basic characteristics.

Among them, from the viewpoints of ease of formation of the pressure-sensitive adhesive film according to the present invention and ability to exert the desired effect of the present invention, it is preferable that the curable compound contains the copolymer (a-2) ) Or (3)), and the above-mentioned form (2) (so-called polymer syrup form) is more preferable.

<(a-1-a) (meth) acrylic acid ester monomer>

The (meth) acrylic acid ester monomer (a-1-a) is not particularly limited as long as it is a form in which an alkyl group or a group represented by - (AO) _p -Q is introduced into the ester moiety of the (meth) acrylic acid ester. In the above "- (AO) _p -Q", A is an alkylene group, Q is an alkyl group, and p is an integer of 1 or more and 20 or less.

The copolymer (a-2) containing the constituent unit (1) derived from the (meth) acrylic acid ester monomer (a-1-a) and / or the (meth) acrylic acid ester monomer (a- ), It is possible to lower the glass transition temperature after curing. As a result, the bending resistance at low temperature can be improved without lowering the adhesion.

The number of carbon atoms of the alkyl group or the group represented by - (AO) _p -Q is not particularly limited. More preferably from 2 to 35, more preferably from 3 to 30, and more preferably from 4 to 28, carbon atoms, from the viewpoint of compatibility and suppressing the glass transition temperature to a low level Particularly preferred. The ester moiety of the (meth) acrylic acid ester may be in the form of a straight chain, a branched chain or a ring, but it is preferably a straight chain or branched chain from the viewpoint of lowering the glass transition temperature. In the case of a ring, the number of carbon atoms is 3 or more.

In the group represented by - (AO) _p -Q, A is preferably an alkylene group having 1 to 4 carbon atoms (that is, a methylene group, an ethylene group, an ethylene group, Propylene group or butylene group), more preferably 2 to 3 carbon atoms (i.e., an ethylene group or a propylene group). At this time, p is preferably an integer of 1 or more and 20 or less, more preferably an integer of 1 or more and 15 or less, and still more preferably 2 or more and 15 or less. Also, Q is an alkyl group. The number of carbon atoms is preferably 1 or more and 12 or less, more preferably 1 or more and 10 or less, and still more preferably 1 or more and 10 or less in view of efficiently exhibiting the desired effect of the present invention Is 1 or more and 8 or less, and 1 or more and 6 or less. Specific examples of such an alkyl group include those listed above.

The (meth) acrylic acid ester monomer (a-1-a) is typically represented by the following formula (1)

Here, in the above formula (1)

R ₁ is a hydrogen atom or a methyl group, and R ₂ is an alkyl group or a group represented by - (AO) _p -Q.

The alkyl group for R ₂ in the formula (1) is not particularly limited, and examples of the alkyl group having 1 to 20 carbon atoms include methyl, ethyl, n-propyl, isopropyl, Cyclohexyl group, 1-methylcyclohexyl group, n-heptyl group, 2-heptyl group, 3-heptyl group, 2-heptyl group, 2-heptyl group, An isohexyl group, an isononyl group, a decyl group, a dodecyl group, a tridecyl group, a tetradecyl group, an isobutyl group, an isobutyl group, an isobutyl group, A pentadecyl group, a hexadecyl group, a heptadecyl group, or an octadecyl group. Particularly, a methyl group, a butyl group, a 2-ethylhexyl group, an n-hexyl group, a nonyl group, and an isononyl group are preferable from the viewpoint of ensuring tackiness and securing basic characteristics.

Specific examples of the (meth) acrylic acid ester monomer (a-1) in which R ₂ in the formula (1) is an alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, (Meth) acrylate, isopentyl (meth) acrylate, isobutyl (meth) acrylate, isobutyl (meth) acrylate, (Meth) acrylate, heptyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl Acrylate, and lauryl (meth) acrylate.

The (meth) acrylic ester monomer (a-1-a) having a group represented by - (AO) _p -Q in R ₂ of the formula (1) has a glass transition temperature of less than -57.0 ° C . Preferably, p is an integer of 2 or more. The group represented by - (AO) _p -Q in R ₂ of formula (1) may be an alkoxyalkyl group. As such an alkoxyalkyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group, a propoxyethyl group, a butoxyethyl group, a methoxypropyl group, a methoxybutyl group and a 2-ethylhexyloxyalkyl group are preferable.

Specific examples of the (meth) acrylic acid ester monomer (a-1) in which R ₂ in the formula (1) is a group represented by - (AO) _p -Q include methoxyethyl (meth) acrylate, ethoxymethyl (Meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, methoxypropyl (Meth) acrylate, ethoxy-triethylene glycol (meth) acrylate, methoxy triethylene glycol (meth) acrylate, methoxy diethylene glycol (meth) acrylate, propoxy diethylene glycol Acrylate, methoxy triethylene glycol (meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxy dipropylene glycol Preferable.

Among the specific examples of the (meth) acrylic acid ester monomer (a-1-a), from the viewpoint of lowering the glass transition temperature and polarity after curing and securing excellent flexibility and adhesiveness, The (meth) acrylic acid ester monomer (a-1-a) containing a homopolymer preferably has a glass transition temperature of less than -60 캜, preferably from -70 캜 to -61 캜, , 2-ethylhexyl acrylate, 2-ethylhexyl-diglycol acrylate, ethoxy-diethylene glycol acrylate and methoxypolyethylene glycol acrylate.

These (a-1-a) components may be used alone or in combination of two or more. Preferably, (a-1-a) component is the above formula (1) R ₂ is the group of (a-1-a-1 ) component and, R ₂ is of the formula (1) of the - (AO) (a-1-a-2) represented by _p- Q can be used.

The component (a-1-a) may be a commercially available product or a synthetic product.

AEH, AME, 2EHA (manufactured by Nippon Shokubai Co., Ltd.), Wright acrylate (registered trademark) EC-A, and Wright acrylate (registered trademark) are commercially available products of the component (a- (Trade name) manufactured by Kyoeisha Chemical Co., Ltd. (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), MTG-A, Light Acrylate (registered trademark) EHDG-AT, Light Acrylate (registered trademark) 130A, Light Acrylate (registered trademark) DPM- (Manufactured by Osaka Organic Chemical Industry Co., Ltd.), AM-90G, AM-130G (manufactured by Shin-Nakamura Kagaku Kogyo Co., Ltd.), Viscot # 190, 2-MTA, MPE400A, MPE550A (Shin-Nakamura Chemical Industry Co., Ltd.)) are suitable.

<(a-1-b) Hydroxyl group-containing (meth) acrylic monomer>

(2) derived from a hydroxyl group-containing (meth) acrylic monomer (a-1-b) and / or a hydroxyl group-containing (meth) acrylic monomer The content of the predetermined crosslinking agent (B) and the photopolymerization initiator (C) is controlled to a certain level by including the main component (A) in the combination (a-2) to secure an excellent adhesion to an optical film such as a polarizing plate can do.

The hydroxyl group-containing (meth) acrylic monomer is a non-amide monomer not containing an amide group and is typically represented by the following formula (2-1):

Here, in the formula (2-1)

R ₅ is a hydrogen atom or a methyl group,

R ₆ is a divalent organic group.

Here, the divalent organic group is not particularly limited, but an alkylene group having 1 to 10 carbon atoms is suitable. Examples of the alkylene group having 1 to 10 carbon atoms include those described above. The alkylene group may have at least one alkyl group having 1 to 8 carbon atoms, a phenoxyalkyl group (the number of carbon atoms in the alkyl group is 1 to 8), a phenoxy group, a phenyl group or a cyclohexyl group as a substituent. The alkyl group having 1 to 8 carbon atoms may be appropriately selected from the above.

In the specific examples of the hydroxyl group-containing (meth) acrylic monomer (2-1), the hydroxyl group-containing (meth) acrylic monomer (2-1) contained in the main component (A) -20 占 폚 or lower, preferably -50 占 폚 or higher and? 30 占 폚 or lower. More specifically, 4-hydroxybutyl (meth) acrylate is particularly preferable.

The hydroxyl group-containing (meth) acrylic monomer may be an amide monomer containing an amide group and may have a structure represented by the following formula (2-2).

Here, in the formula (2-2)

R ₈ is a hydrogen atom or a methyl group,

R ₉ is a single bond or a divalent organic group,

R ₁₀ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

The divalent organic group is not particularly limited, but an alkylene group having 1 to 10 carbon atoms is suitable. The alkylene group may have at least one alkyl group having 1 to 8 carbon atoms, a phenyl group or a cyclohexyl group as a substituent. The alkylene group having 1 to 10 carbon atoms is a divalent substituent obtained by removing one hydrogen atom of an alkyl group having 1 to 10 carbon atoms.

Examples of the alkyl group having 1 to 10 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, A cyclohexyl group, a cyclohexyl group, a 1-methylcyclohexyl group, an n-heptyl group, a 2-heptyl group, a 3-heptyl group, an isoheptyl group, a tert- , A 2-ethylhexyl group, a nonyl group, an isononyl group, and a decyl group.

In the specific examples of the hydroxyl group-containing (meth) acrylic monomer (2-2), the hydroxyl group-containing (meth) acrylic monomer (2-2) contained in the main component (A) It is preferably those having a melting point of 100 deg. C or lower, preferably -20 deg. C or higher and 100 deg. C or lower. More specifically, N-hydroxyethyl (meth) acrylamide is particularly preferable.

From the above, examples of the component (a-1-b) include 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (Meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl ) Acrylamide, N- (1-methyl-2-hydroxyethyl) (meth) acrylamide and N-isopropyl-hydroxy (meth) acrylamide. Among them, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N -Hydroxyethyl (meth) acrylamide and the like are preferable.

(commercially available from Nippon Shokubai Co., Ltd.), 4HBA, CHDMMA (manufactured by Nippon Kasei Co., Ltd.), HEA, HPA, and 4A as commercial products of the component (a-1-b) -L-ester HOP-A (N), Wright acrylate (registered trademark) HOB-A (manufactured by Kyowa Kagakakaku Co., Ltd.) , HEAA (registered trademark) (manufactured by KJ Chemical Co., Ltd.) and N-MAN (manufactured by MIKI RIKEN KOGYO CO., LTD.).

These (a-1-b) components may be used alone or in combination of two or more. The component (a-1-b) may be a commercially available product or a synthetic product.

<(a ') Monomer copolymerizable with component (a-1-a) and component (a-1-b)

The main component (A) may contain a monomer (a ') component copolymerizable with the component (a-1-a) and the component (a-1-b) as long as the object effect of the present invention is achieved. (a'-2) having a polymerizable functional group (hereinafter also referred to as &quot; component (a'-1) &quot; (Hereinafter also referred to as "component (a'-2)") and other polymerizable monomer (a'-3) (hereinafter also referred to as "component (a'-3)").

«(A'-1) Amide group-containing (meth) acrylic monomer»

The (a'-1) component is not particularly limited as long as it has a (non-hydroxylic) amide group in the (meth) acrylic monomer without containing a hydroxyl group. (a'-1) component is typically represented by the following formula (3):

Here, in the formula (3)

R ₈ 'is a hydrogen atom or a methyl group,

R ₉ 'is a single bond or a divalent organic group,

R ₁₀ 'is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms,

R ₁₁ 'is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an acyl group, an epoxy group, an alkoxy group having 1 to 6 carbon atoms, or a dimethylamino group.

The divalent organic group is not particularly limited, but an alkylene group or an acylene group having 1 to 10 carbon atoms is suitable. The alkylene group or the acyl group may have at least one alkyl group having 1 to 8 carbon atoms, a phenyl group or a cyclohexyl group as a substituent.

The alkyl group having 1 to 10 carbon atoms is as described above for Formula (2-2).

The carbon number of the acyl group is not particularly limited, but is preferably 1 to 18 carbon atoms, and more preferably 1 to 6 carbon atoms. The acyl group includes acetoacetoxy group or acetyl group.

Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy, ethoxy, propyloxy, isopropyloxy, butoxy, sec-butoxy, tert- -Hexyloxy group, 3-hexyloxy group, cyclohexyloxy group and the like are suitable.

In addition, R ₁₀ 'and R ₁₁ ' may form a ring having 2 to 8 carbon atoms, and may have an oxygen atom (that is, an oxygen-containing heterocyclic group) or a sulfur atom (that is, a sulfur-containing heterocyclic group) .

(Meth) acryloyl morpholine, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, diacetone , N-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butoxymethylacrylamide, N-isobutoxymethyl acrylamide, N-methoxymethylacrylamide, (Meth) acryloylpolyamine, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, Diacetone (meth) acrylamide, and (meth) acrylamide. Further, the amide group-containing (meth) acrylic monomer (a'-1) may be N, N'-methylenebis (meth) acrylamide.

(registered trademark), DEAA (registered trademark) (manufactured by KJ Chemical Co., Ltd.), DAAm (registered trademark), and the like are commercially available products of the component (a'- NBMA, IBMA, NMMA, TBAA, and MBAA (manufactured by MRC Unitech Co., Ltd.) are suitable.

«(A'-2) Polymerizable functional group-containing macromonomer»

The main component (A) according to the present invention may contain a macromonomer (a'-2) having a polymerizable functional group. The component (a'-2) is a high molecular weight monomer having a polymerizable functional group (unsaturated group), and is composed of a polymer chain portion and a polymerizable functional group portion.

The polymer (cured) obtained by using such a monomer is included in the adhesive film, so that the bending resistance (bending resistance) is improved. The mechanism is believed to be different depending on the glass transition temperature of the polymer chain portion of the macromonomer. Concretely, when the glass transition temperature of the polymer chain portion is high, the polymer chain portion forms a hard segment in the pressure-sensitive adhesive film, so that a cohesive force is generated in the pressure-sensitive adhesive film. By this, it is considered that the adhesive force to the substrate is improved and the bending resistance is improved. On the other hand, when the glass transition temperature of the polymer chain portion of the macromonomer is low, the pressure-sensitive adhesive film becomes soft and the followability to the substrate increases, thereby improving the bending resistance. In addition, the above mechanism is based on speculation, and the present invention is not limited to this mechanism.

The polymerizable functional group of the component (a'-2) is preferably a group having an ethylenically unsaturated double bond (ethylenic unsaturated group). Specifically, it is preferably at least one selected from the group consisting of a vinyl group, an allyl group, a (meth) acryloyl group, and a propenyl group. The polymerizable group is preferably present at the end of the macromonomer, and it is more preferable that the polymerizable group exists only at one end of the macromonomer from the standpoint of stability at the time of polymerization. However, the polymerizable group may be present as a side chain of the macromonomer or may be present at both ends of the chain of the macromonomer.

The polymer chain portion of the component (a'-2) may be at least one member selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, stearyl (meth) (Meth) acrylate, t-butyl (meth) acrylate, styrene, (meth) acrylonitrile, hydroxy (Co) polymer is preferable. These polymer chain moieties may be composed of a single repeating unit or a plurality of repeating units. When the polymer chain is a copolymer comprising a plurality of repeating units, the repeating form thereof is not limited, and may be any of an alternating copolymer, a random copolymer, and a block copolymer.

The component (a'-2) is typically represented by the following formula (4):

In the formula (4), R ₁₂ represents a hydrogen atom or a methyl group, and X ₁ represents a single bond or a divalent linking group.

Examples of the divalent linking group include straight chain, branched or cyclic alkylene groups, aralkylene groups, and arylene groups. These may also have a substituent such as a hydroxyl group or a cyano group. The number of carbon atoms of the alkylene group is preferably 1 or more and 10 or less, and more preferably 1 or more and 4 or less. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, an octylene group and a decylene group. Among them, a methylene group, an ethylene group, a propylene group and the like are preferable. The number of carbon atoms of the aralkylene group is preferably 7 or more and 13 or less. Examples of the aralkylene group include a benzylidene group and a cinnamylidene group. The number of carbon atoms of the arylene group is preferably 6 or more and 12 or less. Examples of the arylene group include a phenylene group, a cumeneylene group, a mesitylenylene group, a tolylene group and a xylylenylene group. Among them, a phenylene group is preferable.

Among the divalent linking groups, the groups represented by -NR ₂ -, -COO-, -OCO-, -O-, -S-, -SO ₂ NH-, -NHSO ₂ -, -NHCOO-, -OCONH- or heterocyclic A group to be introduced may be interposed as a coupler. R ₂ is a hydrogen atom or an alkyl group such as a methyl group, an ethyl group or a propyl group.

In the above formula (4), X ₂ is preferably a methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, stearyl (meth) (Meth) acrylate, t-butyl (meth) acrylate, styrene, and (meth) acrylonitrile, or a polymer obtained by homopolymerizing or copolymerizing one or more monomers selected from Organosiloxane). Among them, X ₂ is preferably a polymer obtained by homopolymerizing methyl (meth) acrylate, styrene, n-butyl (meth) acrylate or isobutyl (meth) acrylate, a (meth) acrylonitrile and styrene Or a polyorganosiloxane. From the viewpoint of durability at a high temperature, X ₂ is preferably a polymer obtained by homopolymerizing methyl (meth) acrylate, styrene and isobutyl (meth) acrylate or copolymerizing (meth) acrylonitrile and styrene Is particularly preferred. Or, from the viewpoint of bending resistance at low temperatures, X ₂ is preferably a polyorganosiloxane, and particularly preferably a polydimethylsiloxane. In addition, as long as the performance of the pressure-sensitive adhesive is not affected, a part of the methyl group of the polydimethylsiloxane may be replaced by a hydrogen atom or an organic group other than the methyl group (ethyl group, phenyl group, etc.).

The above polydimethylsiloxane can be obtained by hydrolysis and condensation of dimethyldialkoxysilane such as dimethyldimethoxysilane and dimethyldiethoxysilane. At this time, an organic group other than a methyl group can be introduced into the polydimethylsiloxane by using an alkoxysilane having an organic group other than the methyl group (for example, diethyldiethoxysilane or the like) in combination. In addition to the dialkoxy silane compound, a small amount of a trialkoxy silane compound may be added.

The number average molecular weight (Mn) of the component (a'-2) is preferably in the range of 2000 to 20000, more preferably in the range of 2000 to 10000, and more preferably in the range of 4000 to 8000 More preferable. When the number average molecular weight (Mn) is 2000 or more, the performance of the pressure-sensitive adhesive can be improved even when the amount of the component (a'-2) added in the copolymer (a-2) is small. On the other hand, if it is 20,000 or less, the viscosity of the pressure-sensitive adhesive is low and workability is good. The value of the number average molecular weight (Mn) can be controlled by appropriately selecting the amounts of chain transfer agent and polymerization initiator to be added to the polymerization system. In the present invention, the number average molecular weight (Mn) of the macromonomer shall be a value in terms of polystyrene measured by GPC (Gel Permeation Chromatography).

The component (a'-2) may be a commercially available product or a synthetic product. (a'-2) is synthesized, the synthesis method is not particularly limited. For example, (1) a polymer chain (living polymer anion) constituting a macromonomer by living anionic polymerization is prepared, A method in which a phosphoric acid chloride or the like is allowed to act; (2) a method in which a radical polymerizable monomer such as methyl methacrylate is polymerized in the presence of a chain transfer agent such as mercaptoacetic acid to obtain an oligomer having a carboxyl group at the terminal and then reacted with glycidyl methacrylate or the like; (3) polymerizing a radically polymerizable monomer such as methyl methacrylate in the presence of an azo-based polymerization initiator containing a carboxyl group to obtain an oligomer having a carboxyl group at the terminal thereof and then forming a macromonomer with glycidyl methacrylate Method can be used.

By preparing a macromonomer using the above-described method, for example, the following groups are introduced as the divalent linking group represented by X ₁ in the formula (4).

(trade name: 45% AA-6 (AA-6S)) having a methacryl group at the terminal and a polymer chain portion of polymethylmethacrylate (PMMA) as a commercially available product of the component (a'- (Trade name: AS-6S, AS-6, manufactured by TOAGOSEI CO., LTD.) In which the polymer chain portion is polystyrene, a styrene / acryl (Trade name: AN-6S; manufactured by TOAGOSEI CO., LTD.), A polymeric chain moiety having polybutyl acrylate (product name: AB-6, manufactured by TOAGOSEI CO., LTD.), (Trade name: AW-6S; manufactured by TOAGOSEI CO., LTD.) And a macromonomer having a polymer chain portion of polydimethylsiloxane (trade name: AK-5; manufactured by TOAGOSEI CO., LTD.). These macromonomers may be used alone or in combination of two or more.

«(A'-3) Other Polymerizable Monomers»

Specific examples of the other polymerizable monomer copolymerizable with the component (a-1-a) and the component (a-1-b) include glycidyl (meth) acrylate, methylglycidyl An acrylic monomer having an epoxy group such as a carboxylate; Amino groups such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, N-tert-butylaminoethyl (meth) acrylate and 2 - ((meth) acryloxy) ethyltrimethylammonium chloride A (meth) acrylic monomer having a hydroxyl group; (Meth) acryl monomers having a urethane group such as urethane (meth) acrylate; (meth) acrylic vinyl monomers having a phenyl group such as p-tert-butylphenyl (meth) acrylate and o-biphenyl (meth) acrylate; Vinyl monomers having silane groups such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (? -Methoxyethyl) silane, vinyltriacetylsilane and methacryloyloxypropyltrimethoxysilane; Styrene, chlorostyrene, alpha -methylstyrene, vinyltoluene, vinyl chloride, vinyl acetate, vinyl propionate, acrylonitrile, and vinyl pyridine. These other monomers may be used alone or in combination of two or more.

&Quot; Content of each component in the above (1) form &quot;

The content of the component (a-1-a) is preferably 70% by mass or more with respect to the total amount of the main component (A) from the viewpoint of lowering the glass transition temperature after curing. The upper limit of the content of the component (a-1-a) is preferably 99.9% by mass or less, because it is excellent in various durability, excellent in bending resistance at high temperature, and improved in adhesion at high temperature. The content of the component (a-1-a) is more preferably 75% by mass or more and 95% by mass or less, more preferably 75% by mass or more from the viewpoint of securing an excellent adhesive force while lowering the glass transition temperature after curing of the pressure- 90 mass% or less, and more preferably 80 mass% or more and 90 mass% or less.

(a-1-a) in the component (a-1-a) is preferably not less than 70% by mass and not more than 99.5% by mass with respect to the total amount of the main component (A) from the viewpoint of lowering the glass transition temperature after curing, Preferably 75 mass% or more and 95 mass% or less, 75 mass% or more and 90 mass% or less, or 80 mass% or more and 90 mass% or less.

(a-1-a-2) in the component (a-1-a) is preferably 0 mass% or more and 30 mass% or less based on the total amount of the main component (A) from the viewpoint of lowering the glass transition temperature after curing, 1 mass% or more and 15 mass% or less, 1 mass% or more and 10 mass% or less, or 1 mass% or more and 5 mass% or less.

The content of the component (a-1-b) is preferably not less than 0.1% by mass and not more than 30% by mass, more preferably not less than 5% by mass and not more than 25% by mass with respect to the total amount of the main component (A) Or less, 10 mass% or more and 25 mass% or less, and 10 mass% or more and 20 mass% or less.

The content of the monomer of the formula (2-1) in the component (a-1-b) is preferably not less than 0.1% by mass and not more than 30% by mass with respect to the total amount of the main component (A) from the viewpoints of improvement in adhesion and durability By mass, more preferably not less than 5% by mass nor more than 20% by mass nor more than 10% by mass nor more than 20% by mass.

The content of the monomer of the formula (2-2) in the component (a-1-b) is preferably 0% by mass or more and 10% by mass or less, more preferably 0.1% by mass or less, from the viewpoint of improvement in adhesion and durability, More preferably not less than 10 mass% and more preferably not less than 0.1 mass% nor more than 5 mass%, more preferably not less than 0.1 mass% nor more than 3 mass% nor more than 0.1 mass% nor more than 1 mass%.

The content of the component (a ') is preferably 0 mass% or more and 10 mass% or less with respect to the total amount of the main component (A). The content of the component (a ') is more preferably 0% by mass or more and 5% by mass or less from the viewpoint of sufficiently securing the amount of the component (a-1) or the component (a-1-b).

&Quot; Form (2) &quot;

In one embodiment according to the present invention, the main component (A) comprises the constituent unit (1) derived from the component (a-1-a), the component (a- 2 (hereinafter also simply referred to as a copolymer (a-2)) containing the constituent unit (2) derived from the 1-b-component (the curable compound is in the form of a monomer and a polymer ). (A-1-a), the component (a-1-b) and the component (a '), which are added as needed, in the raw monomers of the copolymer (a- Called polymer syrup, which is a solvent for dissolving the copolymer (a-2).

(A-1-a), the component (a-1-b) and the component (a ') in the form of the component (2) Content &quot;, and thus the description thereof is omitted here. The suitable content of the components (a-1-a), (a-1-b) and (a ') referred to herein refers to the content of a part of the components before copolymerization. The appropriate content of the unreacted component (a-1-a), component (a-1-b) and component (a ') after copolymerization of a part of the copolymer (a -2) and the ratio of the constituent units constituting the core copolymer (a-2)) can be considered to be preferable.

The preferable content of each constituent unit of the copolymer (a-2) contained in the form of (2) is the same as the content of each component (( (a-1-a), (a-1-b) and (a ').

That is, the copolymer (a-2) contained in the form of (2) is a copolymer comprising 70 to 99.9% by mass of a constituent unit derived from the (meth) acrylic acid ester monomer (a- (A (a-1-b)) copolymerizable with the component (a-1-a) and the component (a-1-b) , The total amount of the constituent units derived from the above components (a-1-a), (a-1-b) and (a ') is 100% or more and 100% The copolymer (a-2) contained in the form of (2) is more preferably a structural unit derived from a (meth) acrylic acid ester monomer (a-1-a) (A-1-a) and (a-1-b), from 75 mass% to 95 mass% of the structural units derived from the hydroxyl group-containing (meth) acrylic monomer -1-b) component (component (a ') derived from copolymerizable monomer 0% by weight 5% or more by weight or less (however, the (a-1-a) component, (a-1-b) and a component (a ') the total amount of structural units derived from the 100 mass%) contains.

The content of the copolymer (a-2) relative to the total amount (total mass) of the main component (A) in the form of the copolymer (2) is preferably such that the applicability of the pressure- Is not less than 4% by mass and not more than 20% by mass, and more preferably not less than 6% by mass and not more than 12% by mass. The content of the copolymer (a-2) can be controlled by, for example, controlling the polymerization rate in a bulk polymerization method using a photopolymerization initiator described later.

&Quot; Form (3) &quot;

As a form according to the present invention, there can be mentioned a form in which the main component (A) is composed of the copolymer (a-2) (in which the curable compound is composed only of a polymer).

A suitable content of each constituent unit of the copolymer (a-2) contained in the form of the component (3) is not particularly limited so long as the content of each component described in the section &quot; content of each component in the form of (1) (the component (a-1-a), the component (a-1-b), and the component (a ')).

[Production of copolymer (a-2)] [

The method for producing the copolymer (a-2) which can be contained in the main component (A) in the form of the above (2) or (3) is not particularly limited, and a solution polymerization method using a polymerization initiator, Known methods such as an emulsion polymerization method, a suspension polymerization method, a reverse phase suspension polymerization method, a thin film polymerization method and a spray polymerization method can be used. Examples of polymerization control methods include an adiabatic polymerization method, a temperature control polymerization method, and an isothermal polymerization method. As the polymerization initiator, any of a thermal polymerization initiator and a photopolymerization initiator may be used. In addition to or in addition to the method of initiating polymerization by a polymerization initiator, a method of initiating polymerization by irradiating active energy rays such as radiation, electron beam, and ultraviolet ray may be employed. Among them, the solution polymerization method using a thermal polymerization initiator or the bulk polymerization method using a photopolymerization initiator is more preferable since the molecular weight can be easily controlled and impurities can also be reduced. That is, in the step of producing the copolymer (a-2) which may be contained in the main component (A) as shown in the examples, the photopolymerization initiator (C) is not required to be used as the polymerization initiator. In the form of (2) or (3), the main component (A) obtained by the process for producing the copolymer (a-2) which can be contained in the main component (A) By adding the initiator (C), a pressure-sensitive adhesive composition can be formed. Namely, the photopolymerization initiator (C) is used in the step of curing the pressure-sensitive adhesive composition to form the pressure-sensitive adhesive film, and the copolymer (a-2) capable of being contained in the main component (A) It is not always necessary to use them (see Examples). Of course, the photopolymerization initiator (C) may be used even in the step of producing the copolymer (a-2) which may be contained in the main component (A) (conventional crosslinking agent).

In one embodiment of the pressure-sensitive adhesive composition of the present invention, the copolymer (a-2) is obtained by copolymerizing the (meth) acrylic acid ester monomer (a-1-a) and the hydroxyl group- b) by solution polymerization of the reaction solution. As a solution polymerization method using a thermal polymerization initiator, for example, by using ethyl acetate, toluene, methyl ethyl ketone or the like as a solvent, a thermal polymerization initiator (a-2) is added to 100 parts by mass of the total amount of the starting monomers of the copolymer Preferably at least 0.01 part by mass and at most 1 part by mass, and the reaction is carried out at a reaction temperature of 40 占 폚 or more and 90 占 폚 or less (or 60 占 폚 or more and 90 占 폚 or less) under a nitrogen atmosphere for 3 hours to 10 hours Method.

Examples of the thermal polymerization initiator include 2,2-azobisisobutyronitrile (AIBN), 2,2'-azobis (2-methylbutyronitrile), azobiscyanovaleric acid, 2 , 2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis 2-methylpropionate), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile) 2-methylpropionamide], 2,2'-azobis (N-butyl-2-methylpropionamide), 2,2'-azobis [2- Azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2'-azobis 2-methylpropionamidine) hydrate, 2,2'-azobis [N- (2-carboxyethyl) Bis (2-imidazolin-2-yl) propane], 2,2'-azobis (1-imino-1-pyrrolidino- Azo compounds such as azobis [2-methyl-N- (2-hydroxyethyl) propionamide]; tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethyl hexanoate, di-tert-butyl peroxide, cumene hydroperoxide, benzoyl peroxide, tert- Organic peroxides such as roper oxide; Inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate. These thermal polymerization initiators may be used alone or in combination of two or more. According to this method, the main component (A) comprising the copolymer (a-2) can be obtained (the form of the above (3)). Further, by adding the obtained copolymer (a-2) to the component (a-1-a) and the component (a-1-b) (Polymer syrup) comprising the copolymer (a-1) and the copolymer (a-2).

The bulk polymerization method using a photopolymerization initiator is not particularly limited. For example, the raw material monomer of the copolymer (a-2) and a photopolymerization initiator are added, and the reaction initiation temperature is usually 20 ° C or more and 35 ° C or less And the active energy ray is irradiated. A method in which the reaction is stopped by introducing air into the reaction system at a stage where the temperature in the reaction system has risen from 5 ° C or more and 15 ° C or less from the reaction start temperature to obtain the copolymer (a-2). At this time, it is not necessary to react all of the raw monomers to be used, and the reaction may be stopped at a stage where the desired polymerization conversion rate (= appropriate viscosity) is obtained. The component (a-1-a), the component (a-1-b) and the component (a '), which are unreacted raw monomers, are added as a solvent to dissolve the copolymer (a- According to this method, the main component (A) (polymer syrup) comprising the component (a-1-a), the component (a-1-b) and the copolymer (a- .

Examples of the active energy ray used in the bulk polymerization method include ultraviolet rays (UV), visible light, laser beam, alpha ray, beta ray, gamma ray, X ray and electron beam. However, , Ultraviolet rays are suitably used in terms of cost. That is, in one preferred embodiment of the pressure-sensitive adhesive composition of the present invention, the copolymer (a-2) is obtained by copolymerizing the (meth) acrylic acid ester monomer (a-1-a) and the hydroxyl group- -1-b) by irradiation of ultraviolet rays. More preferably, ultraviolet light having a wavelength of 200 nm or more and 400 nm or less is used. The ultraviolet rays can be irradiated using a light source such as a high pressure mercury lamp, a microwave excitation type lamp, a chemical lamp, or a black light. The roughness is preferably in the 0.1mW / cm ² or more than 20.0mW / cm ^2.

Examples of the photopolymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethylketal, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1- (4- Methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one, 2-hydroxy- Acetophenones such as phenylpropan-1-one; Benzophenones such as benzophenone, 4-chlorobenzophenone, 4,4'-diazobenzophenone; Benzoin ethers such as benzoin propyl ether and benzoin ethyl ether; Thioxanthones such as 4-isopropylthioxanthone; 1-hydroxycyclohexyl phenyl ketone, xanthone, fluorenone, camphorquinone, benzaldehyde, anthraquinone, and the like. These photopolymerization initiators may be used singly or in combination of two or more.

The photopolymerization initiator may be a commercially available product. Examples of commercially available products include commercially available products such as Irgacure (registered trademark) 127, 184, 819, 907, 651, 1700, 1800, 819, 369, 261, DAROCUR (Registered trademark) KIP150, TZT (manufactured by DKSH Japan Co., Ltd.), Kayacure (registered trademark) (registered trademark) manufactured by BASF Japan Co., BMS, DMBI (manufactured by Nippon Kayaku Co., Ltd.), and the like.

The amount of the photopolymerization initiator to be used is preferably 0.0005 parts by mass or more and 1 part by mass or less, more preferably 0.002 parts by mass or more and 0.5 parts by mass or less, based on 100 parts by mass of the total amount of the raw monomers of the copolymer (a-2).

In order to control the molecular weight during the synthesis of the copolymer (a-2), a chain transfer agent may also be used. Examples of the mercapto compound include methyl mercaptan, t-butyl mercaptan, decylmercaptan, benzyl mercaptan, lauryl mercaptan, stearyl mercaptan, n-dodecylmercaptan, t-dodecylmercaptan, mercaptoacetic acid, Mercaptans such as propionic acid and its ester, 2-ethylhexyl thioglycol and octyl thioglycolate; Alcohols such as methanol, ethanol, propanol, n-butanol, isopropanol, t-butanol, hexanol, benzyl alcohol and allyl alcohol; Halogenated hydrocarbons such as chloroethane, fluoroethane and trichlorethylene; Carbonyls such as acetone, methyl ethyl ketone, cyclohexanone, acetophenone, acetaldehyde, propionaldehyde, n-butylaldehyde, furfural, benzaldehyde and the like; Methyl-4-cyclohexene-1,2-dicarboxylic acid anhydride, and alpha -methylstyrene. These may be used alone or in combination of two or more.

In the present invention, the weight average molecular weight (Mw) of the copolymer (a-2) is preferably 1 million or more and 2.5 million or less, and more preferably 1.2 or more and 2.0 million or less. When the weight-average molecular weight is 1 million or more, the durability and the occurrence of peeling and peeling are suppressed, and the adhesion is improved. On the other hand, if it is less than 2.5 million, the viscosity of the copolymer solution becomes appropriate, and workability such as coatability is improved.

In the present invention, the glass transition temperature of the copolymer (a-2) is preferably less than -57.0 DEG C, more preferably -59.0 DEG C or less. Preferably, the lower limit of the glass transition temperature of the copolymer (a-2) of the present invention is -100 deg. C, more preferably -80 deg. Within the above range, peeling or peeling does not occur even when the pressure-sensitive adhesive film is subjected to a bending operation at a low temperature and at a high temperature, and the folding resistance under two conditions of high temperature and low temperature is excellent.

[Crosslinking agent (B)]

The pressure-sensitive adhesive composition of the present invention contains a predetermined cross-linking agent (B) in view of being capable of effectively suppressing and preventing occurrence of peeling or peeling even if the adhesive is strengthened under both the high temperature and low temperature conditions .

Specifically, the crosslinking agent (B) may be a crosslinking agent having a (meth) acrylate group and a urethane group (-N-C (= O) -). Therefore, when the crosslinking agent (B) is contained in the pressure-sensitive adhesive composition, cracking of the display element and peeling of the pressure-sensitive adhesive layer can be prevented when the display is bent, and the adhesive force can be excellent. Preferably, the crosslinking agent (B) may further comprise an ethylene oxide group. Specifically, the cross-linking agent (B) is a polymer comprising at least one of a compound (constitutional unit) represented by the following formula (5) and a compound (constitutional unit) represented by the following formula (6) (Hereinafter, also referred to as a polymer crosslinking agent (B)), which is a polymer having the formula (6) as an essential component.

In the formula (5), R ₁ is a hydrogen atom or a methyl group. R ₂ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms. R ₃ is a hydrogen atom or a methyl group. m is 0 or 1; n is an integer of 1 or more and 5 or less. When R ₂ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms, m is 0.

In the formula (6), R ₄ is a hydrogen atom or a methyl group. R ₅ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms. R ₆ is a hydrogen atom or a methyl group. m is 0 or 1, n is an integer more than 1 and less than 5, when the R ₅ has 2 carbon atoms more than 8 alkylene group, an ethylene oxide group or propylene oxide of less than date, m is 0.

The alkylene group of R ₂ and R ₅ preferably has 2 to 8 carbon atoms, more preferably 2 to 4 carbon atoms, from the viewpoints of improving adhesion and improving durability and efficiently exhibiting the desired effect of the present invention . Examples of the alkylene group having 2 to 8 carbon atoms include methylene, ethylene, propylene, isopropylene, butylene, sec-butylene, Cyclohexylene group, 1-methylcyclohexylene group, n-heptylene group, 2-heptylene group, 3-heptylene group, isoheptylene group, tert-heptylene group, n-octyl Isobutylene group, tert-octylene group, 2-ethylhexylene group and the like are suitable.

The above-mentioned n in the formulas (5) and (6) may be an integer of 1 or more and 5 or less, preferably 1 or more and 2 or less, from the viewpoints of improving adhesion and durability and effectively exhibiting the desired effects of the present invention. Is more preferable.

It is preferable that the polymer crosslinking agent (B) has a weight average molecular weight (Mw) of 2000 to 30000, and further contains methyl methacrylate and a macromonomer as a constitutional unit. Specifically, the weight average molecular weight (Mw) of the polymeric crosslinking agent (B) is preferably in the range of 2000 to 30000, more preferably in the range of 2000 to 20000, more preferably in the range of 3000 to 18000 Is more preferable. If the weight average molecular weight (Mw) is 2000 or more, the crosslinked structure of the pressure-sensitive adhesive film as a cured product of the pressure-sensitive adhesive composition is strengthened and the modulus of elasticity at high temperature is improved. In addition, even if the amount of the polymeric crosslinking agent (B) Can be improved. On the other hand, if it is 30,000 or less, compatibility with the copolymer (a-2) is good and defects such as whitening of the pressure-sensitive adhesive film (cured product) can be avoided. In addition, the viscosity of the pressure-sensitive adhesive composition is low and workability is good. The value of the weight average molecular weight (Mw) can be controlled by appropriately selecting the amounts of the polymerization initiator (C) and the chain transfer agent to be added to the polymerization system. In the present invention, the weight average molecular weight (Mw) of the polymeric cross-linking agent (B) is to be a polystyrene equivalent value measured by GPC (gel permeation chromatography).

The content of the polymeric crosslinking agent (B) is preferably from 100 parts by mass to 100 parts by mass of the main component (A) from the viewpoint that the adhesive strength is enhanced and the occurrence of peeling or peeling can be effectively suppressed even under bending operation under both high- More preferably 0.1 parts by mass or more and 5 parts by mass or less, more preferably 0.1 parts by mass or more and 3 parts by mass or less, 0.2 parts by mass or more and 2 parts by mass or less, and 0.1 parts by mass or more More preferably 1 part by mass or less. If the content of the polymeric crosslinking agent (B) is within the above range, the gelation rate can be improved, and further, there is a technical effect that both adhesion and bending resistance are compatible. Particularly, when the content of the polymer crosslinking agent (B) is 0.05 parts by mass or more, preferably 0.1 parts by mass or more, the crosslinking structure of the pressure-sensitive adhesive film as a cured product of the pressure-sensitive adhesive composition is strengthened and the modulus of elasticity at high temperature is improved. The adhesive film as a cured product is difficult to recede, and the adhesive film (cured product) is preferable because it is easy to maintain its shape. On the other hand, when the content of the polymer crosslinking agent (B) is 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 3 parts by mass or less, compatibility with the copolymer (a-2) It is preferable that the viscosity is not excessively increased, the sheet is produced well, the adhesive strength is high, and the moisture and heat resistance is excellent.

In the polymer crosslinking agent (B), a polymerizable monomer may be used as a raw material. Specifically, a polymerizable monomer constituting the compound (constituent unit) represented by the formula (1)) or a compound (constituent unit) represented by the formula (2) and a polymerizable monomer copolymerizing with the compound The polymer crosslinking agent (B) which is a polymer containing at least one of the compound (constitutional unit) represented by the formula (1) and the compound (constitutional unit) represented by the following formula (2) can be formed. Examples of the polymerizable monomer used for the raw material of the polymer crosslinking agent (B) include (meth) acrylic acid aryl esters such as phenyl (meth) acrylate and benzyl (meth) acrylate; Salts of (meth) acrylic acid and (meth) acrylic acid alkali metal salts; (Meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl Alkyl acrylate esters; Acrylonitrile; Methacrylonitrile; Vinyl acetate; Vinylidene chloride; Halogenated vinyl compounds such as 2-chloroethyl (meth) acrylate; (Meth) acrylic acid esters of alicyclic alcohols such as cyclohexyl, 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, Oxazoline group-containing polymerizable compounds such as zolin; Aziridine group-containing polymerizable compounds such as (meth) acryloyl aziridine and 2-aziridinyl ethyl (meth) acrylate; Epoxy group-containing vinyl monomers such as (meth) acrylic acid glycidyl ether and (meth) acrylic acid-2-ethyl glycidyl ether; Fluorine-containing vinyl monomers such as fluorine-substituted (meth) acrylic acid alkyl esters; Salts of unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, and fumaric acid, and (partial) ester compounds and acid anhydrides thereof; Reactive halogen-containing vinyl monomers such as 2-chloroethyl vinyl ether and vinyl monochloroacetate; Amide group-containing vinyl monomers such as methacrylamide, N-methylol methacrylamide, N-methoxyethyl methacrylamide and N-butoxymethyl methacrylamide; Vinylsilane group-containing vinyl compound monomers such as vinyltrimethoxysilane,? -Methacryloxypropyltrimethoxysilane, aryltrimethoxysilane, trimethoxysilylpropylarylamine, and 2-methoxyethoxytrimethoxysilane ; In addition, macromonomers having a radical polymerizable vinyl group (e.g., a fluorine-based monomer, a silicon-containing monomer, a macromonomer, styrene, silicone, etc.) at the end of a monomer polymerized with a vinyl group can be exemplified. In particular, by using a macromonomer constituted by methyl methacrylate, compatibility with the main component (A) can be improved, and the adhesive strength can be enhanced without depending on the amount of the polymer crosslinking agent. Even if the bending operation is performed under two conditions of high temperature and low temperature, It is possible to effectively suppress and prevent the occurrence of the overrunning.

The polymeric cross-linking agent (B) may be incorporated into the composition by itself, but may be contained as a solution containing the polymeric cross-linking agent (B). The solution may contain at least one of the monomers described in the main component (A). And the content of the monomer added at this time is insignificant compared with the content described in the main component (A). The content of the formula (5) or (6) in the solution is not particularly limited, but is preferably 1% by mass or more and 80% by mass or less, more preferably 5% by mass or more and 60% Or more and 40 mass% or less. When the content of the formula (5) or (6) in the polymer crosslinking agent (B) in the solution is 1% by mass or more and 80% by mass or less, the crosslinking structure of the pressure-sensitive adhesive film as a cured product of the pressure- If the content of the formula (5) or (6) in the polymer crosslinking agent (B) in the solution is 5 mass% or more and 60 mass% or less and 10 mass% or more and 40 mass% or less, The crosslinking structure is strengthened and the modulus of elasticity at high temperature is improved.

Further, by using the polymer crosslinking agent (B), it is possible to prevent the adhesive film (cured product) from being retreated or the adhesive force from becoming too low even when used in a relatively large amount. This makes it possible to increase the amount of the cross-linking agent (B) used and prevent the characteristics of the pressure-sensitive adhesive film (cured product) from being changed due to an error in mixing.

The method of synthesizing the polymeric crosslinking agent (B) is not particularly limited, and conventionally known synthesis methods can be used. For example, a method of synthesizing a polymer having a hydroxyl group and then adding a (meth) acrylate having an isocyanate group to obtain the polymer crosslinking agent (B) and a method of synthesizing a polymer having an isocyanate group, There is a method of adding the hydroxyl group and (meth) acrylate to obtain the polymer crosslinking agent (B). The method for synthesizing the polymer having a hydroxyl group or an isocyanate group is not particularly limited and conventionally known synthesis methods can be used and known polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization can be used . Among them, the solution polymerization method using a thermal polymerization initiator is more preferable since the molecular weight can be easily controlled and the amount of impurities can be reduced.

As a solution polymerization method using a thermal polymerization initiator, for example, ethyl acetate, toluene, methyl ethyl ketone or the like is used as a solvent and 100 parts by mass of the total amount of the starting monomers of the copolymer (a-2) , A method of adding a thermal polymerization initiator in an amount of preferably 0.5 parts by mass or more and 20 parts by mass or less and allowing the reaction to proceed at a reaction temperature of 40 占 폚 or more and 120 占 폚 or less for 1 hour to 10 hours under a nitrogen atmosphere, have. Examples of the thermal polymerization initiator include 2,2-azobisisobutyronitrile (AIBN), 2,2'-azobis (2-methylbutyronitrile), azobiscyanovaleric acid, 2 , 2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis 2-methylpropionate), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile) 2-methylpropionamide], 2,2'-azobis (N-butyl-2-methylpropionamide), 2,2'-azobis [2- Azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2'-azobis 2-methylpropionamidine) hydrate, 2,2'-azobis [N- (2-carboxyethyl) Bis (2-imidazolin-2-yl) propane], 2,2'-azobis (1-imino-1-pyrrolidino- Azo compounds such as azobis [2-methyl-N- (2-hydroxyethyl) propionamide]; tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethyl hexanoate, di-tert-butyl peroxide, cumene hydroperoxide, benzoyl peroxide, tert- Organic peroxides such as roper oxide; Inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate. These thermal polymerization initiators may be used alone or in combination of two or more.

The addition reaction of the polymer having a hydroxyl group or an isocyanate group with (meth) acrylate having a hydroxyl group or an isocyanate group may be carried out in the presence of a catalyst. Examples of the catalyst include organic titanic compounds such as tetraethyl titanate and tetrabutyl titanate, organotin compounds such as tin octylate, dibutyltin oxide and dibutyltin dilaurate, stannous chloride, brominating agent 1 And halogen-based stannate such as tin. The amount of the catalyst to be used is not particularly limited and may be appropriately adjusted. For example, the amount of the catalyst is usually about 0.001 part by mass to about 3 parts by mass, relative to 100 parts by mass of the (meth) acrylate having a hydroxyl group or an isocyanate group Is about 0.01 part by mass to 1 part by mass. When the addition reaction of the (meth) acrylate having a hydroxyl group or an isocyanate group with the polymer having a hydroxyl group or an isocyanate group is carried out, a polymerization inhibitor is preferably added in order to inhibit the crosslinking reaction with (meth) . The polymerization inhibitor may be selected from, for example, p-methoxyphenol, hydroquinone, pyrogallol, naphthylamine, tert-butylcatechol, cuprous chloride, 2,6- (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert- butylphenol), nitrosophenylhydroxyamine aluminum salt, Diphenylnitrosamine, and the like.

As the (meth) acrylate having an isocyanate group, a commercially available product or a synthetic product may be used. Examples of commercial products of (meth) acrylate having an isocyanate group include car lens series AOI, MOI, EG-MOI (manufactured by Showa Denko K.K.) and the like.

The polymer crosslinking agent (B) may contain a solvent. When the solvent is contained, the viscosity of the solution of the polymer crosslinking agent (B) is lowered and handling is facilitated. Further, as shown in the examples, it is also possible to use polymerizable (meth) acrylate as a solvent.

The above-mentioned polymer crosslinking agents (B) may be used alone or in combination of two or more.

[Photopolymerization initiator (C)]

The pressure-sensitive adhesive composition according to the present invention comprises a photopolymerization initiator (C). Concretely, the same photopolymerization initiator as used in [Preparation of copolymer (a-2)] can be used. Examples of the photopolymerization initiator (C) include acetophenone, 3-methylacetophenone, benzyldimethylketal, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1- Methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one, 2-hydroxy- (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone), 2-hydroxy- Hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone) Acetophenones; Benzophenones such as benzophenone, 4-chlorobenzophenone, 4,4'-diazobenzophenone; Benzoin ethers such as benzoin propyl ether and benzoin ethyl ether; Thioxanthones such as 4-isopropylthioxanthone; 1-hydroxycyclohexyl phenyl ketone, xanthone, fluorenone, camphorquinone, benzaldehyde, anthraquinone, and the like. Among these, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone and 2-hydroxy- 2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one is preferable because the adhesive film which is a cured product of the pressure-sensitive adhesive composition is less colored and less odor. These photopolymerization initiators may be used singly or in combination of two or more.

The photopolymerization initiator (C) may be a commercially available product. Examples of commercially available products include Irgacure (registered trademark) 127, 184, 819, 907, 651, 1700, 1800, 819, 369, 261, DAROCUR KIP150, KIP160, One, TZT (manufactured by DKSH Japan KK), Kayacure (registered trademark) TPO, DAROCURE TM 1173 (manufactured by BASF Japan KK), Esacure TM KIP150, KAYACURE (registered trademark) BMS, DMBI (manufactured by Nippon Kayaku Co., Ltd.), and the like. In the pressure-sensitive adhesive composition according to the present invention, the main component (A) comprising the curable compound is used in combination with the photopolymerization initiator (C) together with the above-mentioned specific crosslinking agent (B), the glass transition temperature after curing of the pressure- (B) and the photopolymerization initiator (C) can be controlled to a certain degree, whereby the folding resistance can be improved.

Furthermore, by suppressing the content of the photopolymerization initiator (C) to a certain level, it is possible to prevent the adhesive strength and durability of the pressure-sensitive adhesive composition obtained by curing the pressure-sensitive adhesive composition from excessively increasing. Specifically, the content of the photopolymerization initiator (C) is preferably in the range of 0.05 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the main component (A). Thus, in addition to the above effects, when the main component (A) is in the form of a polymer syrup, it is excellent in that the final copolymerization reaction is performed to facilitate the formation of an adhesive film. The amount of the photopolymerization initiator (C) to be added is more preferably 0.1 part by mass or more and 1.0 part by mass or less based on 100 parts by mass of the main component (A).

[Silane coupling agent]

The pressure-sensitive adhesive composition of the present invention may further contain a silane coupling agent. This is because, when a silicon film (film) is used, the adhesion with the silicon film is improved by containing a silane coupling agent.

The silane coupling agent means that it has no siloxane bond and has two or more different reactors in the molecule.

The silane coupling agent used in the pressure-sensitive adhesive composition of the present invention is not particularly limited and includes, for example, 3-glycidoxypropyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxy Silane, n-propyltrimethoxysilane, ethyltrimethoxysilane, diethyldiethoxysilane, n-butyltrimethoxysilane, n-hexyltriethoxysilane, n-octyltrimethoxysilane, phenyltri Vinyltriethoxysilane, vinyltris (? -Methoxyethoxy) silane,? -Trimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane,? -Glycidoxypropyltrimethoxysilane,? -Glycidoxypropyltriethoxysilane,? - methacryloxypropylmethyl Methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ- aminopropyltrimethoxysilane, N -? - (aminoethyl) -? - aminopropyltrimethoxysilane, N -? - (aminoethyl) -? - aminopropyltri Aminopropyltrimethoxysilane,? -Aminopropyltrimethoxysilane,? -Aminopropyltrimethoxysilane,? -Aminopropyltrimethoxysilane,? -Aminopropyltrimethoxysilane,? -Aminopropyltrimethoxysilane,? -Chloropropyltrimethoxysilane,? -Mercaptopropyltrimethoxysilane (3- [triethoxysilyl] propyl) tetrasulfide, [gamma] -isocyanate propyl triethoxysilane, and the like can be given. In addition, a silane coupling agent having a functional group such as an epoxy group (glycidoxy group), an amino group, a mercapto group, or a (meth) acryloyl group, a silane coupling agent containing a functional group having reactivity with these functional groups, A compound having a hydrolyzable silyl group obtained by reacting cyanate with an arbitrary ratio with respect to each functional group can also be used.

As the silane coupling agent, a commercially available product or a synthetic product may be used. Examples of commercially available silane coupling agents include KBM-303, KBM-403, KBE-402, KBE-403, KBE-502, KBE-503, KBM-5103, KBM-573, KBM- , KBE-846, and KBE-9007 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

The silane coupling agents may be used singly or in combination of two or more kinds.

The content of the silane coupling agent in the pressure-sensitive adhesive composition of the present invention is preferably not less than 0 parts by mass and not more than 10 parts by mass, and not less than 0.0001 parts by mass and not more than 10 parts by mass, relative to 100 parts by mass of the main component (A) More preferably 0.01 part by mass or more and 3 parts by mass or less. With such a range, durability can be improved.

[solvent]

The pressure-sensitive adhesive composition of the present invention may contain a solvent. Examples of the solvent include, but are not limited to, esters such as ethyl acetate and n-butyl acetate; Aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; And organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. These solvents may be used alone or in combination of two or more.

When the copolymer (a-2) is synthesized by the bulk polymerization method using a photopolymerization initiator as described above, the copolymer (a-2) called polymer syrup containing at least one of the components (a-1-b) and (a ') as a solvent. Examples of the solvent used in the polymer syrup include the components (a-1-a), (a-1-b) and (a ') exemplified above. Therefore, the pressure-sensitive adhesive composition of the present invention may contain at least one of the components (a-1-a), (a-1-b) and (a ') as a solvent in the composition.

[Other ingredients added]

The pressure-sensitive adhesive composition may contain, if necessary, known additives such as a crosslinking accelerator, an antioxidant, a filler, a colorant (such as a pigment or a dye), an ultraviolet absorber, an antioxidant, a chain transfer agent, a plasticizer, a softener, a surfactant, Other added components) may be contained within a range that does not impair the effects of the present invention.

[Production method of pressure-sensitive adhesive composition]

The method for producing the pressure-sensitive adhesive composition is not particularly limited. For example, when the curable compound in the main component (A) is the monomer (1), the component (a-1-a), the component (a-1-b), the crosslinking agent (B) C), and optionally added components (a '), a silane coupling agent, a solvent and other additive components.

When the curable compound in the main component (A) is the monomer (2), which is composed of the monomer and the polymer, the monomer (a-1-a) A method in which a polymer syrup, a crosslinking agent (B), a photopolymerization initiator (C) and, if necessary, a component (a '), a silane coupling agent, a solvent and other additives are mixed.

When the curable compound in the main component (A) is the polymer (3), the copolymer (a-2) or its solution, the crosslinking agent (B), the photopolymerization initiator (C) A solvent, a solvent, and other additives, and the like.

The method of adding the crosslinking agent (B) and the photopolymerization initiator (C) according to the present invention is not particularly limited. For example, the cross-linking agent (B) and / or the photopolymerization initiator (C) may be added to at least one of the component (a-1-a) The solution (B) and / or the solution (C) prepared by dissolving may be adjusted so as to have a desired content with respect to the total amount of the curable compound constituting the main component (A). Alternatively, as shown in the examples, the polymer syrup may be prepared by dissolving the crosslinking agent (B) and the photopolymerization initiator (C) so as to have a desired content with respect to the total amount of the curable compound constituting the main component (A). Alternatively, the crosslinking agent (B) and the photopolymerization initiator (B) may be added to the copolymer (a-2) or the solution thereof containing only the polymerizable curing compound in the main component (A) so as to have a desired content with respect to the total amount of the curing compound (C) may be dissolved.

[Adhesive film]

In one aspect of the present invention, there is provided a pressure-sensitive adhesive film obtained by curing the pressure-sensitive adhesive composition of the present invention. The pressure-sensitive adhesive film of the present invention is a cured layer of the pressure-sensitive adhesive composition of the present invention, which is obtained by applying (for example, applying) a pressure-sensitive adhesive composition (solution) of the present invention to a suitable substrate . When two or more kinds of curing treatments (drying, crosslinking, polymerization, etc.) are carried out, they can be carried out simultaneously or in multiple steps. In the pressure-sensitive adhesive composition in which the main component (A) contains a monomer of the component (a-1-a) or the component (a-1-b), a final copolymerization reaction is typically carried out as the curing treatment (a-1-a) component, (a-1-b) component and / or copolymer (a-2 and optionally added component (a ')) is subjected to a copolymerization reaction to form a complete polymer ). For example, when an active energy ray-curable pressure-sensitive adhesive composition is used, active energy ray irradiation is performed. If necessary, curing treatment such as crosslinking and drying may be carried out. When it is necessary to dry the composition with an active energy ray-curable pressure-sensitive adhesive composition, the active energy ray curing may be performed after drying. In the pressure-sensitive adhesive composition in which the main component (A) is composed solely of the copolymer (a-2), typically, as the curing treatment, a treatment such as drying (heat drying) or crosslinking is carried out as necessary.

In the application of the pressure-sensitive adhesive composition, one or more kinds of solvents may be appropriately added.

As the base material of the adhesive film, a separator described later can be used.

The coating method is not particularly limited, and various known methods can be used. For example, by roll coater, baker type applicator, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, An extrusion coating method and the like.

Since the pressure-sensitive adhesive composition of the present invention contains the predetermined crosslinking agent (B) and the photopolymerization initiator (C), the pressure-sensitive adhesive composition of the present invention can be coated directly on the adherend, or on a predetermined adherend such as a substrate or separator After coating or coating on one side of a support (substrate), an active energy ray is irradiated to obtain an adhesive film. Usually, the illuminance in the above wavelength 200nm 400nm or less and irradiated to 200mJ / cm ² or more 10000mJ / cm ² or less of 1mW / cm ² more than 200mW / cm ² or less ultraviolet light, the accumulated light quantity is the pressure-sensitive adhesive film obtained by photo-polymerization .

When the pressure-sensitive adhesive composition of the present invention contains a solvent, it is preferable to dry the solvent. As a method of drying the solvent, an appropriate method may be adopted depending on the purpose. Preferably, the coating film is heated and dried. The heat drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and particularly preferably 70 ° C to 170 ° C. By setting the heating temperature to the above range, a pressure-sensitive adhesive film having excellent adhesive properties can be obtained. When the main component (A) is the form of the above-mentioned (3) comprising the copolymer (a-2) (the form in which the curable compound consists solely of a polymer), the curing of the pressure sensitive adhesive composition can be performed by the above-

Further, the drying time can be appropriately set. Preferably 5 seconds or more and 30 minutes or less, more preferably 5 seconds or more and 20 minutes or less, and particularly preferably 10 seconds or more and 15 minutes or less. The heating and drying can be carried out two or more times by changing the conditions. For example, after further drying at a temperature of not less than 40 ° C but not more than 100 ° C for not less than 0.1 minute and not more than 10 minutes, further drying treatment may be performed at not less than 100 ° C and not more than 200 ° C for not less than 1 minute and not more than 20 minutes. This makes it possible to prevent peeling, peeling, and cracking caused by rapid volatilization of the solvent.

The thickness (dry film thickness) of the pressure-sensitive adhesive film of the present invention is not particularly limited and may be appropriately set according to the intended use. For example, in the case of an adhesive film such as an optical film used in a flexible display such as a curved display, it is preferable that the thickness is 1 占 퐉 or more and 200 占 퐉 or less from the viewpoint of adhesiveness and bending resistance. Particularly, when a pressure-sensitive adhesive film is formed using the pressure-sensitive adhesive composition of the present embodiment, even when the thickness of the pressure-sensitive adhesive film is significantly reduced compared with the conventional pressure-sensitive adhesive composition, the same level as the thick film (usually about 200 탆) (Dry film thickness) of the pressure-sensitive adhesive film of the present invention is more preferably 1 탆 or more and 70 탆 or less and more preferably 5 탆 or more and 70 탆 or less in view of obtaining high bending resistance More preferable.

Further, when the adhesive film according to the present invention is exposed, the adhesive film can be protected with a sheet (separator) or the like which has been peeled off until it is provided for practical use.

As the separator, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate (PET) Polyethylene terephthalate (PBT) film, polyurethane film, and ethylene-vinyl acetate copolymer film. Other suitable materials include porous materials such as paper, cloth, and nonwoven fabric, net, foam sheet, metal foil, and suitable paper foil such as a laminate thereof. However, the plastic film is suitably used because of its excellent surface smoothness.

The thickness of the separator is usually 5 占 퐉 or more and 200 占 퐉 or less, preferably 5 占 퐉 or more and 100 占 퐉 or less.

If necessary, the separator can be subjected to antistatic treatment such as mold releasing treatment, antifouling treatment, coating type, kneading type, and vapor deposition type with silicone, fluorine, long chain alkyl or fatty acid amide releasing agent or silica powder . Particularly, the releasability from the pressure sensitive adhesive film can be further improved by appropriately subjecting the surface of the separator to peeling treatment such as silicone treatment, long chain alkyl treatment or fluorine treatment.

The adhesive film may have a glass transition temperature of less than -57.0 ° C. Within the above-mentioned range, in the above-mentioned range, peeling or peeling does not occur even when the pressure-sensitive adhesive film is subjected to the bending operation at a low temperature and a high temperature, and the folding resistance under both high temperature and low temperature conditions is excellent.

A pressure-sensitive adhesive film was prepared by bonding PET (polyethylene terephthalate) film having a thickness of 150 占 퐉 and PET film having a thickness of 100 占 퐉 on both surfaces of a 50 占 퐉 thick pressure-sensitive adhesive film to obtain a PET film having a thickness of 150 占 퐉, an adhesive film having a thickness of 50 占 퐉, Of a three-layer structure bonded to a PET film was bent in a bending test machine with a PET film having a thickness of 150 탆 inward and bent with a radius of curvature of 3 mm to bend and spread. The bending was performed at a bending temperature of -20 캜 at a rate of 30 cycles per minute The minimum number of lifting and bubbling between the adhesive film and the PET film may be 30,000 or more, for example, 30,000 or more and 100,000 or less. Can be used in the flexible display in the above range. Bubbling and bubble generation can be evaluated by a conventional method using a naked eye or an optical microscope.

When the bending temperature is measured at the above-mentioned temperature of 60 DEG C, the minimum number of times that the bubbles are generated can be 30,000 or more, for example, 30,000 or more and 50,000 or less. Can be used in the flexible display in the above range.

The adhesive film preferably has a storage elastic modulus G '(80) at 80 캜 of 2.0 x 10 ⁴ Pa or more from the viewpoint of bending resistance at a high temperature. Preferably, the upper limit of the storage elastic modulus G '(80) of the pressure-sensitive adhesive film at 80 캜 is 4.0 x 10 ⁴ Pa, more preferably 3.5 x 10 ⁴ Pa and 3.0 x 10 ⁴ Pa. Within this range, the bending resistance at high temperatures may be good.

The adhesive film preferably has a storage elastic modulus G '(-20) at -20 캜 of 3.5 x 10 ⁵ Pa or less, preferably 2.6 x 10 ⁵ Pa or less, and 2.55 x 10 ⁵ Pa or less in view of bending resistance at low temperature Or less, and more preferably 2.5 x 10 &lt; ⁵ &gt; Pa or less. Preferably, the lower limit of the storage elastic modulus G '(-20) at -20 캜 of the pressure-sensitive adhesive film is 0.8 x 10 ⁵ Pa, more preferably 0.85 x 10 ⁵ Pa. Within this range, bending resistance at low temperatures may be good.

The adhesive film preferably has a ratio of a storage elastic modulus G '(-20) at -20 ° C to a storage elastic modulus G' (80) at 80 ° C of 1: 0.2 to 1: 1, preferably 1: 0.4 to 1: . In this range, the flexibility of the flexible display can be good because the flexural resistance is good at both the low temperature and the high temperature.

The shear strain under the shear stress of 90 kPa is preferably not less than 800%, more preferably not less than 850% and not less than 900% from the viewpoint of preventing cracking of the display element and peeling of the adhesive layer when the display is bent, , More preferably not less than 1000%, and not more than 2000%, preferably not more than 1900%, not more than 1800%, not more than 1,700%, not more than 1,600%, 1,500% If it is within this range, it is excellent in bending resistance.

The adhesive force of the adhesive film is preferably 450 g / 25 mm or more, more preferably 750 g / 25 mm or more, more preferably 800 g / 25 mm or more, and 4,000 g / 25 mm or less. With such a range, an excellent adhesive force can be exhibited with respect to an optical film and the like.

[Adhesive sheet]

In one aspect of the present invention, there is provided a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive film formed by curing the pressure-sensitive adhesive composition of the present invention. The pressure-sensitive adhesive sheet is a so-called substrate-applied pressure-sensitive adhesive sheet (one-sided or two-sided pressure-sensitive adhesive sheet) prepared by fixing the pressure-sensitive adhesive film on one surface or both surfaces of a sheet-like base material (support) without intention of separating the pressure- Alternatively, the adhesive film may be formed on a substrate having releasability such as a release film (release liner) (a release sheet, a resin sheet subjected to release treatment on the surface, etc.), and a substrate supporting the adhesive film is removed (Double-sided) pressure-sensitive adhesive sheet in the form of a sheet.

The concept of the pressure-sensitive adhesive sheet referred to herein may include what is referred to as an adhesive tape, an adhesive label, an adhesive film, or the like. The adhesive film is not limited to the continuous film, and may be, for example, an adhesive film formed in a regular or random pattern such as a point shape or a stripe shape.

Examples of the substrate (support) include plastic substrates such as polyethylene terephthalate (PET) and polyester film, porous materials such as paper and nonwoven fabric, metal foil and the like.

The constituent material of the plastic substrate is not particularly limited as long as it can be formed into a sheet shape or a film shape, and examples thereof include polyethylene, polypropylene, poly-1-butene, Polyolefins such as ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer and ethylene-vinyl alcohol copolymer; Polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate; Polyamides such as polyacrylate, polystyrene, nylon 6, nylon 6,6, partially aromatic polyamide; Polyvinyl chloride, polyvinylidene chloride, polycarbonate, and the like.

The thickness of the base material is not particularly limited, but is preferably 4 탆 or more and 100 탆 or less, and more preferably 4 탆 or more and 50 탆 or less.

If necessary, the plastic substrate may be subjected to releasing treatment with a releasing agent such as silicone, fluorine, long chain alkyl or fatty acid amide type, silica powder, and the like, antifouling treatment, acid treatment, alkali treatment, primer treatment, corona treatment, plasma treatment, A coating type, a kneading type, a vapor deposition type, or the like.

Examples of the release film (release liner) include the separator exemplified above.

[Usage]

The above-described pressure-sensitive adhesive composition, pressure-sensitive adhesive film and pressure-sensitive adhesive sheet of the present invention are applicable to various applications and can be used, for example, in optical members such as optical films. Such an optical film is not particularly limited and may be those used for forming an image display apparatus such as a liquid crystal display apparatus. For example, at least one of a polarizing plate and a retardation plate, and at least one of a conductive layer and a protective layer, a cover film, a transparent conductive film, a window film, a viewing angle enlarging film for improving the viewing angle of a liquid crystal monitor An optical compensation film, a brightness enhancement film for enhancing the contrast of the display, and further, those having these laminated layers. That is, in one embodiment of the present invention, there is provided an optical member comprising an adhesive film formed by curing a pressure-sensitive adhesive composition according to the present invention.

The pressure-sensitive adhesive composition of the present invention may be used by directly applying the pressure-sensitive adhesive composition on one side or both sides of the optical member to form an adhesive film, or by previously forming an adhesive film on the release film and transferring the adhesive film to one side or both sides of the optical member . Since the pressure-sensitive adhesive composition of the present invention has excellent durability, lifting and peeling of the pressure-sensitive adhesive film by heat treatment and high-humidity treatment can be prevented.

The pressure-sensitive adhesive composition, pressure-sensitive adhesive film and pressure-sensitive adhesive sheet of the present invention are suitably used for an image display apparatus. Examples of the image display device include a liquid crystal display device, an organic EL display device, a plasma display (PDP), a curved display, or a flexible display.

As described above, the present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive film, a pressure-sensitive adhesive sheet, and an image display device, and relates to a pressure-sensitive adhesive sheet having excellent adhesive strength, bending resistance which hardly peels off even when bending is performed under high- Can be provided. In addition, the pressure-sensitive adhesive composition of the present invention is suitably used in the production of various films or sheets used in liquid crystal display devices such as flexible displays, electroluminescence devices, and the like, and can be used in these technical fields.

[ Example ]

The effects of the present invention will be described with reference to the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following embodiments. On the other hand, all parts and% in each example are based on mass. All of the room temperature leaving conditions not specifically defined below are 23 deg. C (room temperature) and 55% RH.

<Viscosity>

The temperature of the main component (A) in the glass bottle was adjusted to 25 캜 and measured by a B-type viscometer.

&Lt; Measurement of weight average molecular weight of copolymer (a-2) >

The weight average molecular weight of the copolymer (a-2) was measured by GPC (gel permeation chromatography).

분석 장치: 토소사 제품, HLC-8120GPC

Analyzer: Toso product, HLC-8120GPC

칼럼: 토소사 제품, G7000H_XL+GMH_XL+GMH_XL

Column: Toso products, G7000H _XL + GMH _XL + GMH _XL

칼럼 크기: 각 7.8mmΦx30㎝ 합계 90㎝

Column size: Each 7.8mmΦx30cm Total 90cm

칼럼 온도: 40℃

Column temperature: 40 DEG C

유량: 0.8 ㎖/분

Flow rate: 0.8 ml / min

주입량: 100㎕

Injection amount: 100 μl

용리액: 테트라하이드로퓨란

Eluent: Tetrahydrofuran

검출기: 시차굴절계(RI)

Detector: Differential refractometer (RI)

표준시료: 폴리스타이렌.

Standard sample: polystyrene.

(Production Example 1)

&Lt; Preparation of main component (A-1) >

The main component (A-1) was prepared as shown below.

The reaction was carried out in a reaction box equipped with four black lights (FL20SBL manufactured by Sankyo Denki Co., Ltd., emission wavelengths of not less than 315 nm and not more than 400 nm) provided on four sides of a UV lamp in an environment shielding ultraviolet rays from the outside.

81 parts by mass of 2-ethylhexyl acrylate (2EHA) (manufactured by Nippon Shokubai Co., Ltd.), 4-hydroxybutyl acrylate (4HBA) (available from Nippon Kasei Co., Ltd.) , 3 parts by mass of methoxypolyethylene glycol acrylate (AM-130G, manufactured by Shin-Nakamura Chemical Co., Ltd.), 1 part by mass of N-hydroxyethylacrylamide (HEAA) (manufactured by KJ Chemical Co., Ltd.) 0.005 part by mass of 2,2-dimethoxy-1,2-diphenylethane-1-one (IRGACURE (registered trademark) 651 manufactured by BASF) was dissolved and dissolved in the monomer solution Followed by UV irradiation at room temperature in a nitrogen atmosphere. Specifically, ultraviolet (UV) (wavelength: 365 nm) at an illumination of 2.5 mW / cm ² was irradiated using black light (FL20SBL, manufactured by Sankyo Denki Co., Ltd.) for polymerization initiation. After the initiation of the reaction (irradiation), the temperature of the reaction system was elevated, but the irradiation of black light was stopped at the stage where the rise of the reaction temperature from the start of the reaction (irradiation) became 7 캜, The reaction was forcibly stopped. That is, the UV irradiation was carried out until the temperature rise from the start time reached 7 캜, thereby obtaining a main component (a-2-1) which was a polymer solution containing the copolymer A-1) (a form of so-called polymer syrup).

The weight average molecular weight of the copolymer (a-2-1) in the main component (A-1) was 1,919,000 (in terms of GPC polystyrene) and the polymerization degree was 10.0%. The viscosity of the main component (A-1) was 1400 mPa s. The content of the copolymer (a-2-1) in the main component (A-1) was 10.0 parts by mass. The above-mentioned &quot; polymerization rate &quot; is a value of the reaction rate calculated by assuming that the case where all the injected monomers are polymers becomes 100% (the same shall apply hereinafter).

(Production Example 2)

&Lt; Preparation of main component (A-2) >

The main component (A-2) was prepared as shown below.

The reaction was carried out in a reaction box equipped with four black lights (FL20SBL manufactured by Sankyo Denki Co., Ltd., emission wavelengths of not less than 315 nm and not more than 400 nm) provided on four sides of a UV lamp in an environment shielding ultraviolet rays from the outside.

70 parts by mass of 2-ethylhexyl acrylate (manufactured by Nippon Shokubai Co., Ltd.) and 4 parts by mass of 4-hydroxybutyl acrylate (manufactured by Nippon Kasei Co., Ltd.) were added to a reaction vessel equipped with a nitrogen gas introducing tube, a thermometer, And 0.005 parts by mass of 2,2-dimethoxy-1,2-diphenylethane-1-one (Irgacure (registered trademark) 651; BASF Corporation) as a polymerization initiator were dissolved and dissolved Dissolved in the monomer solution), and then UV irradiation was performed at room temperature under a nitrogen atmosphere. Specifically, ultraviolet (UV) (wavelength: 365 nm) at an illumination of 2.5 mW / cm ² was irradiated using black light (FL20SBL, manufactured by Sankyo Denki Co., Ltd.) for polymerization initiation. After the initiation of the reaction (irradiation), the temperature of the reaction system was elevated, but the irradiation of black light was stopped at the stage where the rise of the reaction temperature from the start of the reaction (irradiation) became 7 캜, The reaction was forcibly stopped. That is, the UV irradiation was carried out until the temperature rise from the start time reached 7 캜, thereby obtaining the main component (A) which was the polymer solution containing the copolymer (a-2-2) in which a part of the monomer component was polymerized -2) (in the form of a so-called polymer syrup).

The weight average molecular weight of the copolymer (a-2-2) in the main component (A-2) was 2.2 million (in terms of GPC polystyrene) and the polymerization degree was 9.5%. The viscosity of the main component (A-2) was 2500 mPa.. The content of the copolymer (a-2-2) in the main component (A-2) was 9.5 parts by mass.

&Lt; Measurement of Glass Transition Temperature of Homopolymer >

The Tg of the homopolymers shown in Table 2 below is a value determined by DSC according to JIS K7121 (1987). If the catalog value of each maker is a value obtained by the above measurement method, the catalog value of each maker may be applied.

[Evaluation 1]

&Lt; Measurement of glass transition temperature of main component &

The glass transition temperature (Tg) of each main component (or copolymer) can be determined from the monomer units constituting the copolymer (a-2-1, a-2-2) Is a calculated value. The homopolymer Tg of each homopolymer was -64.5 ° C for 2-ethylhexyl acrylate, -37.2 ° C for 4-hydroxybutyl acrylate, -66.6 ° C for methoxypolyethylene glycol acrylate AM-130G, N-hydroxyethyl acrylamide (Tg) of the main component (A-1) was -59.9 占 폚 and the Tg of the main component (A-2) was -57.0 占 폚.

On the other hand, the theoretical glass transition temperature obtained from the formula of FOX agrees well with the measured glass transition temperature determined by differential scanning calorimetry (DSC) or dynamic viscoelasticity.

(Production Example 3)

&Lt; Synthesis of polymer crosslinking agent (B-1) >

92 g of anhydrous toluene was placed in a reaction vessel equipped with a stirrer, a nitrogen gas introducing tube, a thermometer, a stirrer, and a reflux condenser. The mixture was stirred for 1 hour while introducing nitrogen into a water bath at 80 ° C and then methyl methacrylate monomer 10 g of 4-hydroxybutyl acrylate (manufactured by Nippon Kasei Co., Ltd.), 17.5 g of a polymethyl methacrylate macromonomer (macromonomer AA-6, manufactured by Toagosei Co., Ltd.) A monomer solution obtained by mixing 2.26 g of 2'-azobis (2-methylpropionate) (V-601; manufactured by Wako Junyaku Kogyo Co., Ltd.) and 30 g of anhydrous toluene was added dropwise over 1 hour. After the dropwise addition, the mixture was aged for 4 hours. The water bath was changed to an oil bath, and the oil bath was heated to 120 ° C and further aged for 2 hours. After the temperature was returned to room temperature, 2.3 g of an anhydrous toluene solution containing a 5% polymerization inhibitor (Q-1301, N-nitrosophenylhydroxylamine aluminum salt; manufactured by Wako Pure Chemical Industries, Ltd.) and 2-isocyanate as an acrylate having an isocyanate group 5.41 g of ethyl acrylate (Carol AOI (registered trademark) manufactured by Showa Denko K.K.), and 6 g of 0.5% dibutyltin dilaurate toluene solution were added in this order, followed by stirring for 1 hour. Thereafter, the reflux tube was changed to a Dean-Stark tube, and the oil bath was set at 120 ° C. When 100 ml of toluene was distilled off, 98.5 g of 2-ethylhexyl acrylate and 17.4 g of 4-hydroxybutyl acrylate were added. After stirring for 1 hour, distillation of toluene was removed, and a 33% polymer crosslinking agent (B-1) solution was obtained. (The 33% polymer crosslinking agent (B-1) solution had a concentration of 33 mass% of the polymer crosslinking agent (B-1) as a solid component.) This was diluted with the acrylic monomer by solvent substitution, (B-2) solution and the 33% polymeric crosslinking agent (B-3) solution are the same). The weight average molecular weight of the crosslinking agent (B-1) was 1.3,000 (in terms of GPC polystyrene). The resulting polymeric crosslinking agent (B-1) has a structure in which R ₄ in the formula (6) is hydrogen, R ₅ is an n-butylene group, R ₆ is hydrogen, n is 1 and m is 1.

(Production Example 4)

&Lt; Synthesis of polymer crosslinking agent (B-2) >

92.3 g of anhydrous toluene was placed in a reaction vessel equipped with a stirrer, a nitrogen gas introducing tube, a thermometer, a stirrer, and a reflux tube. The mixture was stirred for 1 hour while introducing nitrogen in a water bath at 80 DEG C, and then methyl methacrylate monomer 10 g of 4-hydroxybutyl acrylate (manufactured by Nippon Kasei Co., Ltd.), 17.5 g of a polymethyl methacrylate macromonomer (macromonomer AA-6, manufactured by Toagosei Co., Ltd.), 22.5 g of dimethyl 2 , 2.40 g of 2'-azobis (2-methylpropionate) (V-601, manufactured by Wako Pure Chemical Industries, Ltd.) and 30 g of anhydrous toluene were added dropwise over 1 hour. After the dropwise addition, the mixture was aged for 4 hours. The water bath was changed to an oil bath, and the oil bath was heated to 120 ° C and further aged for 2 hours. After returning to room temperature, 2.3 g of an anhydrous toluene solution of 5% polymerization inhibitor (Q-1301, N-nitrosophenylhydroxylamine aluminum salt, manufactured by Wako Pure Chemical Industries, Ltd.) and 0.2 g of an isocyanate as the methacrylic acid ester having an isocyanate group 2-ethoxyethyl acrylate (CH ₃ C (CH ₂ ) -C (═O) - (O-CH ₂ CH ₂ ) - (O-CH ₂ CH ₂ ) 6.75 g of Methacryloyloxy ethyloxy] ethyl isocyanate (Karenz MOI-EG (registered trademark) manufactured by Showa Denko K.K.) and 6 g of 0.5% dibutyltin dilaurate toluene solution were added in this order, followed by stirring for 1 hour. Thereafter, the reflux tube was changed to Dean & Stark, and the oil bath was set at 120 ° C. When 100 ml of toluene was distilled off, 101.9 g of 2-ethylhexyl acrylate and 18.0 g of 4-hydroxybutyl acrylate were added. After stirring for 1 hour, distillation of toluene was removed, and a 33% polymer crosslinking agent (B-2) solution was obtained. The weight average molecular weight of the polymeric crosslinking agent (B-2) was 1.7 thousand (in terms of GPC polystyrene). The resulting polymeric crosslinking agent (B-2) is a structure in which R ₄ in the formula (6) is hydrogen, R ₅ is an n-butylene group, R ₆ is a methyl group, n is 2 and m is 1.

(Production Example 5)

&Lt; Synthesis of polymer crosslinking agent (B-3) >

138.6 g of anhydrous acetic acid ethyl was placed in a reaction vessel equipped with a stirrer, a nitrogen gas introducing tube, a thermometer, a stirrer and a reflux tube, stirred for 1 hour while introducing nitrogen in a water bath at 70 ° C, and then 2-methoxyethyl acrylate (Manufactured by TOAGOSEI CO., LTD.), 10 g of 2-isocyanate ethyl acrylate (CALENS AOI (registered trademark) manufactured by Showa Denko K.K.) as an acrylic acid ester having an isocyanate group, 9.39 g of azobis (2,4-dimethylvaleronitrile) (V-65; manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 1 hour. After the dropwise addition, the mixture was aged for 4 hours and further aged at 90 ° C for 4 hours. (Product of Wako Pure Chemical Industries, Ltd.) 2.8 g of anhydrous ethyl acetate solution, 10.0 g of 4-hydroxybutyl acrylate (product of Nippon Kasei Co., Ltd.) 10.1 g, and 0.5 g of dibutyltin dilaurate anhydrous ethyl acetate solution (6 g), and the mixture was stirred for 1 hour. Thereafter, the reflux tube was changed to a Dean-Stark tube, and the oil bath was set at 90 캜. At the time when 100 ml of ethyl acetate was distilled off, 119.7 g of 2-ethylhexyl acrylate and 21.1 g of 4-hydroxybutyl acrylate were added. After stirring for 1 hour, ethyl acetate was removed by distillation, and a 33% polymer crosslinking agent (B-3) solution was obtained. The weight average molecular weight of the polymeric crosslinking agent (B-3) was 0.4 (GPC polystyrene equivalent). The resulting polymeric crosslinking agent (B-3) has a structure in which R _{1 in} the formula (5) is hydrogen, R ₂ is an n-butylene group, R ₃ is hydrogen, n is 1 and m is 1.

(Example 1)

(Preparation of pressure-sensitive adhesive composition)

1.5 parts by mass of the polymeric crosslinking agent (B-1) obtained in Production Example 3 (content of the solid content of 33% by weight solution), 100 parts by mass of the photopolymerization initiator (C), 100 parts by mass of the main component (A- (IRGACURE (registered trademark) 184, manufactured by BASF Japan Co., Ltd.) was mixed and subjected to a mixing and defoaming treatment to obtain a photopolymerizable pressure-sensitive adhesive composition.

(Formation of adhesive film)

Then, this photopolymerizable pressure-sensitive adhesive composition (coating liquid) was applied onto a PET film (trade name: MRF50, manufactured by Mitsubishi Kagaku Polyester Film Co., Ltd., thickness: 50 占 퐉) subjected to a releasing treatment with a silicone type release agent as a release film with a Baker type applicator So as to have a coating thickness of 50 mu m, thereby forming a coating film. A PET film (release film) subjected to releasing treatment by the above-mentioned silicone type releasing agent is further superimposed on the coating film so that a release film is arranged above and below the coated film of the pressure-sensitive adhesive composition to laminate (seal) Respectively. Thereafter, ultraviolet light (wavelength: 365 nm) having an illuminance of 2.5 mW / cm ² was irradiated (total light amount: 1500 mJ / cm ² ) for 10 minutes using black light (FL20SBL manufactured by Sankyo Denki Co., Ltd.) The coating film of the composition was cured. As a result, a pressure-sensitive adhesive sheet in which a colorless transparent adhesive film having a thickness of 50 占 퐉 was held between two PET films was obtained.

(Example 2)

A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were prepared in the same manner as in Example 1, except that the polymeric crosslinking agent (B-2) was used instead of the polymeric crosslinking agent (B-1)

(Example 3)

A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were prepared in the same manner as in Example 1, except that the polymeric crosslinking agent (B-3) was used instead of the polymeric crosslinking agent (B-1)

(Example 4)

A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were prepared in the same manner as in Example 1 except that 0.5 parts by mass of the polymer crosslinking agent (B-1) was used instead of 1.5 parts by mass of the polymer crosslinking agent (B-1).

(Comparative Example 1)

1,6-hexanediol diacrylate (light acrylate 1,6-HDDA, manufactured by Kyoeisha Kakaku Co., Ltd.) was used instead of 1.5 parts by mass of the polymeric crosslinking agent (B-1) in Example 1 A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were prepared in the same manner as in Example 1. The pressure-

(Comparative Example 2)

Except that 1.5 parts by mass of 1,6-hexane diol diacrylate (light acrylate 1,6-HDDA, manufactured by Kyoeisha Kakaku K.K.) was used in place of the polymeric crosslinking agent (B-1) in Example 1, A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were prepared in the same manner as in Example 1. [

(Comparative Example 3)

A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were prepared in the same manner as in Example 1 except that the main component (A-2) was used instead of the main component (A-1)

&Lt; Measurement of storage elastic modulus &

The pressure-sensitive adhesive sheet obtained in each of the Examples and Comparative Examples was cut into a size of 1.0 mm x 1.0 mm, and the two PET films were peeled off, and the pressure-sensitive adhesive film was taken out and laminated to have a thickness of 3 mm. The pressure-sensitive adhesive film (pressure-sensitive adhesive composition after curing) after lamination was attached to a dynamic viscoelasticity measuring device (Exstar DMS7100, Hitachi High-Tech Science Co., Ltd.). The storage elastic modulus G '(-20) at -20 ° C and the storage elastic modulus G' (-20) at 80 ° C were measured at a temperature range of -30 ° C to 100 ° C at a temperature of 5 ° C / (80) were measured. The obtained results are shown in Tables 3 and 4 below.

&Lt; Measurement of Glass Transition Temperature after Curing of Pressure-Sensitive Adhesive Composition >

The glass transition temperature after curing was measured using the pressure-sensitive adhesive composition prepared in each of the Examples and Comparative Examples. That is, the measurement is carried out by the DSC method according to JIS K7121 (1987), and these results are the same as those obtained by measuring the glass transition temperature (Tg) of the main component (copolymer) do. The obtained results are shown in Tables 3 and 4.

[evaluation]

&Lt; Measurement of gel fraction &

The gel fraction of the pressure-sensitive adhesive composition prepared in each of the Examples and Comparative Examples was measured. The gel fraction was determined by the following method. That is, about 0.1 g of the pressure-sensitive adhesive composition was weighed and the weight W ₁ (g) was measured. This was taken in a sample bottle, and about 30 g of ethyl acetate was added and left for 24 hours. The contents of the sample bottle after the lapse of a predetermined time were filtered by a 200 mesh stainless steel wire netting (the weight of the membrane was W ₂ (g)), and the weight of the whole wire W ₃ (g) Were measured. The gel fraction was calculated from the measured values by the following formula (2). The obtained results are shown in Tables 3 and 4 below.

<Measurement of Adhesive Force>

Two PET films were peeled from the pressure-sensitive adhesive sheet obtained in each of the Examples and Comparative Examples, and the pressure-sensitive adhesive film was taken out.

Two pieces of PET film (trade name: MRF50, manufactured by Mitsubishi Chemical Corporation) having a thickness of 50 占 퐉 were prepared and corona treatment was performed on the surface on which the PET film was not subjected to the peeling treatment. The pressure-sensitive adhesive film was bonded to the surface subjected to the corona treatment using a laminator, cut into a width of 25 mm and a length of 100 mm, and then subjected to autoclave treatment at 50 DEG C and 0.5 MPa for 15 minutes. Thereafter, the film was allowed to stand in an atmosphere of 23 ° C and 55% RH for 1 hour, and the adhesive strength was measured. Corona treatment was performed by passing the PET film through the corona irradiating part set at a speed of 1.6 m / min and a voltage of 9.5 kV using a 3DT corona treating system (manufactured by Poly DYNE) twice.

The adhesive force was measured at a peeling angle of 180 ° and a peeling speed of 0.3 m / min using a tensile tester (Tensilon universal material tester STA-1150, Orientech Co., Ltd.) under an atmosphere of 23 ° C and 55% RH according to JIS Z0237 (G / 25 mm) when the PET film was pulled off according to the test method of the pressure-sensitive adhesive tape and the pressure-sensitive adhesive sheet. The obtained results are shown in Tables 3 and 4 below.

<Measurement of Shear Deformation>

The pressure-sensitive adhesive composition obtained in each of the Examples and Comparative Examples was applied to a PET film (trade name: MRF50, manufactured by Mitsubishi Chemical Corporation) having a thickness of 50 占 퐉 by using a Baker type applicator to obtain a coated film. The obtained coating film was irradiated with ultraviolet light (wavelength: 365 nm) at an illumination of 2.5 mW / cm ² for 10 minutes (total light amount: 1500 mJ / cm ² ) using black light to cure the coating film. As a result, a pressure-sensitive adhesive film having a thickness of 50 mu m was obtained.

The shear strain of the adhesive film was evaluated by TA.XT_Plus Texture Analyzer (Stable Micro System) at 25 ° C.

1, a PET (polyethylene terephthalate) film (thickness: 75 占 퐉) of width x length (50 mm x 20 mm) was coated with an adhesive film of width x length x thickness (20 mm x 20 mm x 50 m) Were adhered to each other and a PET film, an adhesive film, and a PET film were stacked in this order, and a contact area between the PET film and the adhesive film was measured as a width x length (20 mm x 20 mm). A jig was fixed to both ends of the PET film of the specimen. The contact area between the PET film and the jig was set to be a width x length (15 mm x 20 mm). (Unit: 占 퐉, X _o ) of the adhesive film at a rate of 300 mm / min at a rate of 10% of the initial thickness of the pressure-sensitive adhesive film, X ₃ ), reached a length of 1000% of the thickness of the adhesive film, held for 10 seconds, restored at the same speed (300 mm / min) as the pulling speed, and the adhesive film when a force of 0 kPa was applied to the adhesive film The increased length is referred to as X ₂ (unit: 탆). Referring to FIG. 2, a graph was obtained by plotting the stretched length of the adhesive film on the X-axis and the force applied on the adhesive film on the Y-axis. When the stretched length of the adhesive film when a force of 90 kPa is applied to the adhesive film is X ₁ (unit: 탆), the shear strain is a value calculated by the following formula 1. The obtained results are shown in Tables 3 and 4 below.

<Formula 1>

Shear strain = (X ₁ ) / (X ₀ ) x 100

<Measurement of folding resistance (bending test)>

Two PET films were peeled from the pressure-sensitive adhesive sheet obtained in each of the Examples and Comparative Examples, and a 50 占 퐉 -thick adhesive film was taken out. A PET film (trade name: A4300, manufactured by Toyobo Co., Ltd.) A PET film (trade name: A4100, manufactured by TOYOBO CO., LTD.) Having a thickness of 100 mu m was superimposed on the pressure-sensitive adhesive film having a thickness of 50 mu m by using a laminate and autoclaved for 15 minutes at 50 DEG C and 0.5 MPa Respectively. Thus, a pressure-sensitive adhesive sheet in which two sheets of PET films were bonded by a pressure-sensitive adhesive film having a thickness of 50 mu m was obtained.

Using a bending tester (trade name: Bending tester, manufactured by Tester Sangyo Co., Ltd.), the obtained pressure sensitive adhesive sheet was tested under the conditions of a low temperature environment of -20 占 폚 and a high temperature environment of 60 占 폚. (30 cycles per minute = 30 cycles / min, repetition frequency: 30,000 times) with a curvature of 3 mm, and visually confirmed whether peeling, peeling, wrinkling, etc. of the adhesive film and PET film occurred. The evaluation results are shown in Tables 3 and 4 below. If the evaluation result is &quot;? &Quot;, it is practicable.

(Evaluation standard)

○: 박리, 들뜸, 주름 등이 없었던 것을 나타낸다

○: indicates that there was no peeling, peeling, or wrinkling

×; 박리, 들뜸이 있었던 것을 나타낸다.

×; Peeling, and peeling.

* Mass part: The content of the solution of the solid content of 33% by weight prepared in preparation examples 3 to 5

As shown in Table 4, the pressure-sensitive adhesive composition of the present invention is excellent in adhesion to optical films and the like, and peeling or peeling does not occur even when the film is subjected to bending operation under two conditions of high temperature and low temperature. In addition, the pressure-sensitive adhesive composition according to the present invention has a shear deformation of 800% or more, so that it can be predicted that cracking of the display element and detachment of the adhesive layer when the display is bent are prevented. Therefore, the pressure-sensitive adhesive composition according to the present invention is particularly suitable for flexible display applications.

On the other hand, Comparative Examples 1 and 2, which did not include the polymer crosslinking agent of the present invention, had low adhesion to the optical film, and were peeled off or peeled even after bending operation under both high temperature and low temperature conditions for the bonded film, The strain was less than 800%.

In Comparative Example 3 in which the glass transition temperature of the pressure-sensitive adhesive composition after curing was -57.0 占 폚, the adhesive force to the optical film was low and peeling or peeling was observed even when the bending operation was performed under the low temperature condition for the bonded film.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (20)

As the pressure-sensitive adhesive composition,
(A), a crosslinking agent (B) and a photopolymerization initiator (C), each of which is composed of a curable compound,
The main component (A) is a mixture (a-1) of a (meth) acrylic acid ester monomer (a-1-a) and a hydroxyl group-containing (meth) acrylic monomer (a-1-b); (1) derived from the (meth) acrylic ester monomer (a-1-a) and the structural unit (2) derived from the hydroxyl group-containing (meth) acrylic monomer (a-1-b) (A-2), wherein the copolymer (a-2)
Wherein the crosslinking agent (B) is a polymer comprising at least one of a compound represented by the following formula (5) and a compound represented by the following formula (6)
Wherein the pressure-sensitive adhesive composition has a glass transition temperature after curing of less than -57.0 DEG C,

(In the above formula (5)
R ₁ is a hydrogen atom or a methyl group,
R ₂ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms,
R ₃ is a hydrogen atom or a methyl group, m is 0 or 1, n is an integer of 1 or more and 5 or less,
When R ₂ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms, m is 0,
In the formula (6)
R ₄ is a hydrogen atom or a methyl group,
R ₅ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms,
R ₆ is a hydrogen atom or a methyl group, m is 0 or 1, n is an integer of 1 or more and 5 or less, and when R ₅ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms, 0).
The pressure-sensitive adhesive composition according to claim 1, wherein the crosslinking agent (B) has a weight-average molecular weight of 2000 to 30000, and further contains methyl methacrylate and a macromonomer as constituent units.
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the storage elastic modulus at 80 ° C after curing is 2.0 x 10 ⁴ Pa or more.
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the storage elastic modulus at -20 ° C after curing is 3.5 x 10 ⁵ Pa or less.
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the shear strain under a shear stress of 90 kPa after curing is 800% or more.
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the gel fraction is 50% or more and 90% or less.
(Meth) acrylic acid ester monomer (a-1-a-1) having an alkyl group, and - (AO) (meth) acrylic acid ester monomer (a-1) having a group represented by _p- Q (wherein A is an alkylene group having 1 to 4 carbon atoms, p is an integer of 1 or more and 20 or less, and Q is an alkyl group having 1 to 12 carbon atoms) -a-2). &lt; / RTI &gt;
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the hydroxyl group-containing (meth) acrylic monomer (a-1-b) comprises a monomer having a glass transition temperature of the homopolymer of -20 캜 or lower.
The pressure-sensitive adhesive composition according to claim 8, wherein the hydroxyl group-containing (meth) acrylic monomer (a-1-b) further comprises a hydroxyl group-containing (meth) acrylic monomer having an amide group.
The positive resist composition as claimed in claim 1 or 2, wherein the total amount of the main component (A) is at least 75 mass% and not more than 95 mass% of the (meth) acrylic ester monomer (a- (Meth) acrylic monomer (a-1-b) in an amount of 5% by mass or more and 25% by mass or less.
A pressure-sensitive adhesive film obtained by curing the pressure-sensitive adhesive composition according to any one of claims 1 to 3.
A glass transition temperature of less than -57.0 DEG C,
A polyethylene terephthalate (PET) film having a thickness of 150 占 퐉 and a PET film having a thickness of 100 占 퐉 were bonded to both sides of a 50 占 퐉 thick adhesive film to form a PET film having a thickness of 150 占 퐉, an adhesive film having a thickness of 50 占 퐉, When the bonded three-layered specimen was bent at a bending temperature of -20 DEG C at a bending speed of 30 cycles / min by bending a PET film having a thickness of 150 mu m inwardly with a curvature radius of 3 mm, Adhesive film having a minimum number of lifting and bubbles between adhesive film and PET film of 30,000 times or more.
13. The method of claim 12, wherein the adhesive film has a minimum number of times of lifting and bubbling between the adhesive film and the PET film when the bending is performed at the bending temperature of 60 DEG C at a bending speed of 30 cycles / Lt; / RTI &gt;
The pressure-sensitive adhesive film according to claim 12, wherein the pressure-sensitive adhesive film has a storage elastic modulus G '(80) at 80 ° C of 2.0 x 10 ⁴ Pa or more.
The pressure-sensitive adhesive film according to claim 12, wherein the pressure-sensitive adhesive film has a storage elastic modulus G '(- 20) of not more than 3.5 x 10 ⁵ Pa at -20 캜.
The adhesive film according to claim 12, wherein the adhesive film has a ratio of a storage elastic modulus G '(-20) at -20 캜 to a storage elastic modulus G' (80) at 80 캜 of 1: 0.2 to 1: .
The pressure-sensitive adhesive film according to claim 12, wherein the pressure-sensitive adhesive film has a shear strain of 800% or more under a shear stress of 90 kPa.
The method according to claim 12, wherein the pressure-
(A), a crosslinking agent (B) and a photopolymerization initiator (C), each of which is composed of a curable compound,
The main component (A) is a mixture (a-1) of a (meth) acrylic acid ester monomer (a-1-a) and a hydroxyl group-containing (meth) acrylic monomer (a-1-b); (1) derived from the (meth) acrylic ester monomer (a-1-a) and the structural unit (2) derived from the hydroxyl group-containing (meth) acrylic monomer (a-1-b) (A-2), wherein the copolymer (a-2)
Wherein the crosslinking agent (B) is formed of a pressure-sensitive adhesive composition having a (meth) acrylate group, a urethane group and an ethylene oxide group.
The adhesive film according to claim 18, wherein the crosslinking agent (B) is a polymer comprising at least one of a compound represented by the following formula (5) and a compound represented by the following formula (6)

(In the above formula (5)
R ₁ is a hydrogen atom or a methyl group,
R ₂ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms,
R ₃ is a hydrogen atom or a methyl group, m is 0 or 1, n is an integer of 1 or more and 5 or less,
When R ₂ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms, m is 0,
In the formula (6)
R ₄ is a hydrogen atom or a methyl group,
R ₅ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms,
R ₆ is a hydrogen atom or a methyl group, m is 0 or 1, n is an integer of 1 or more and 5 or less, and when R ₅ is an alkylene group, an ethylene oxide group or a propylene oxide group having 2 to 8 carbon atoms, 0).
An image display device comprising the adhesive film of claim 12.

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