KR20190074202A - Adhesive for repeatedly foldable device, adhesive sheet, repeatedly foldable laminate member and repeatedly foldable device - Google Patents

Abstract

The present invention relates to an adhesive for a repeatedly curved device, which suppresses deformation of an adhesive layer, an adhesive sheet, a repeatedly curved stacked member, and a repeatedly curved device. The adhesive for a repeatedly curved device is prepared by crosslinking a (meth)acrylic acid ester polymer (A) and an adhesive composition containing a cross-linking agent (B).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet, a repetitive bending laminated member, and a repetitive bending device,

The present invention relates to a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet for repeatedly bending devices, and a repeatedly bending laminated member and a repeated bending device.

BACKGROUND ART [0002] In recent years, a display capable of bending has been proposed as a display (display) of an electronic apparatus, which is a kind of a device. Such a flexible display is, for example, used for a stationary display provided on a column on a curved surface by bending, or for a mobile display which can be folded, folded or rounded, It is expected.

Examples of the flexible display include an organic electroluminescence (organic EL) display, an electrophoretic display (electronic paper), a liquid crystal display using a plastic film as a substrate, and the like.

In such a bendable display, it is generally considered that one bendable member (bendable member) constituting the bendable display and another bendable member are bonded by the adhesive layer of the adhesive sheet. Here, as a conventional pressure sensitive adhesive sheet for display which can not be bent, for example, those shown in Patent Documents 1 and 2 are known.

The bendable display is not curved once but is repeatedly bent (bent) as described in Patent Document 3. [ Further, in such a repetitive bendable display, there is a case where it is fixed in a bent state for a long period of time. When the conventional adhesive sheet is used for the repeated bendable display for such an application, the pressure-sensitive adhesive layer is deformed after the bending state is released, and the bendable display is largely curved and hardened in the bending state.

Japanese Patent Laid-Open Publication No. 2015-174907 Japanese Patent Application Laid-Open No. 2016-774 Japanese Patent Application Laid-Open No. 2016-2764

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and it is an object of the present invention to provide a pressure-sensitive adhesive sheet which, after being released from a bending state in the case of repeatedly bending or in a long- A pressure-sensitive adhesive sheet and a pressure-sensitive adhesive sheet for repeated bending devices capable of alleviating the influence of repeated bending of the bending device or the effect of being placed in a bending state, and a pressure-sensitive adhesive sheet for releasably releasing from the bending state And a repetitive bending laminated member and a repetitive bending device capable of relieving the influence of the repetitive bending or the effect of being placed in the bending state after the bending.

In order to achieve the above object, firstly, the present invention provides a pressure-sensitive adhesive for repeated bending devices for bonding one bendable member constituting a device repeatedly bent to another bendable member, characterized in that the pressure- maximum relaxation elastic modulus value of which is measured when 10% strain sikyeoteul the maximum relaxation modulus G (t) _max (MPa), and the art maximum relaxation modulus G (t) _max is measured after 3757 seconds of the pressure-sensitive adhesive of 10% until in the relaxation modulus variation ΔlogG (t) calculated from the deformation and, at least mitigate the elastic modulus G (t) to at least mitigate the elastic modulus value of _min (MPa) in the formula (I) or less as measured therebetween, the pressure-sensitive adhesive The creep compliance value measured when a stress of 3000 Pa is applied is defined as a minimum creep compliance J (t) _min (MPa ^-1 ), and the minimum creep compliance J (t) _min is measured until 3757 seconds after the minimum creep compliance J The creep compliance variation value? LogJ (t) _max (MPa ^-1 ) calculated from the following formula (II) is determined by setting the maximum creep compliance value measured during the period of time at which the maximum creep compliance value J t) is 3 or less (Invention 1).

Logg (t) = logG (t) _max -logG (t) _min ... (I)

LogJ (t) = logJ (t) _max- logJ (t) _min ... (II)

In the above invention (Invention 1), by satisfying the physical properties described above, it is possible to suppress deformation of the pressure-sensitive adhesive layer even after release from the bending state in the case of repeated bending applied to the repeated bending device, Thereby preventing the repeated bending device from hardening in a largely curved state, and thus reducing the influence of the repeated bending of the repeated bending device due to the effect of being placed in a bent state.

In the above invention (Invention 1), it is preferable that the modulus of elastic modulus ΔlogG (t) is 1.1 or less (Invention 2).

In the above invention (Invention 1 or 2), it is preferable that the creep compliance variation value logj (t) is 2.82 or less (Invention 3).

In the invention (inventions 1 to 3), it is preferable that the pressure-sensitive adhesive is a pressure-sensitive adhesive comprising a pressure-sensitive adhesive composition obtained by crosslinking a pressure-sensitive adhesive composition containing a (meth) acrylic acid ester polymer (A) and a crosslinking agent (B).

Secondly, the present invention relates to a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer for bonding one bendable member constituting a device repeatedly bent and another bendable member, wherein the pressure-sensitive adhesive layer comprises a pressure- (5). ≪ / RTI >

In the invention (Invention 5), the pressure-sensitive adhesive sheet includes two release sheets, and the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to contact the release surfaces of the two release sheets (Invention 6).

Thirdly, the present invention is a repeatedly bending laminated member having one bending member and another bending member constituting a device to be repeatedly bent, and a pressure-sensitive adhesive layer for bonding the one bending member and the other bending member to each other, Layer is a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (invention 5 or 6) (invention 7).

In the invention (invention 7), it is preferable that at least one of the one bendable member and the other bendable member is a display element (invention 8).

Fourth, the present invention provides a repetitive bending device having the above-described repeated bending laminated member (inventions 7 and 8) (Invention 9).

INDUSTRIAL APPLICABILITY The pressure-sensitive adhesive sheet and the pressure-sensitive adhesive sheet for a repeated bending device according to the present invention are resistant to deformation of the pressure-sensitive adhesive layer after being released from a bending state when the bending device is repeatedly bent or repeatedly bent, The influence due to the repeated bending of the repeated bending device or the effect of being placed in the bending state can be alleviated. The repeatedly bending laminated member and the repeated bending device according to the present invention can be used in the case of repeated bending or in a state of being in a long bending state, Can be mitigated.

1 is a sectional view of a pressure-sensitive adhesive sheet according to an embodiment of the present invention;
2 is a sectional view of a repeated bending laminated member according to an embodiment of the present invention;
3 is an explanatory diagram (side view) for explaining a static bending test.
Fig. 4 is an explanatory diagram (side view) explaining the deformation amount of the test piece as the test result of the bending test. Fig.

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

[Adhesive for repeated bending device]

The pressure-sensitive adhesive for a repeated bending device according to the present embodiment (hereinafter, simply referred to as "pressure-sensitive adhesive") is a pressure-sensitive adhesive for bonding one bending member constituting the repeated bending device to another bending member. The repeated bending device and the bending member will be described later.

The pressure-sensitive adhesive according to the present embodiment has a maximum relaxation modulus of elasticity G (t) _max (MPa) measured when 10% of the pressure-sensitive adhesive is deformed in accordance with JIS K7244-1, , The pressure-sensitive adhesive is continuously deformed by 10% from the measurement of G (t) _max until 3757 seconds, and the minimum relaxation modulus value measured therebetween is defined as the minimum relaxation modulus G (t) _min (MPa) (T) _min (MPa ^-1 ), and the creep compliance value measured when a stress of 3000 Pa is applied to the pressure-sensitive adhesive is defined as minimum creep compliance J (t) _min (MPa ^-1 ) is then measured and the creep compliance J (t) _min and continuing to 3000Pa stress until after 3757 seconds, and the maximum value of the creep compliance is measured in between the maximum creep compliance ^{_{J (t) max (MPa -1}} ), The following formula (II) This creep compliance value variation ΔlogJ (t) with the multiplication value (ΔlogG (t) × ΔlogJ (t)) calculated from, but not more than 3.

Logg (t) = logG (t) _max -logG (t) _min ... (I)

LogJ (t) = logJ (t) _max- logJ (t) _min ... (II)

Details of the measurement method of the modulus of elasticity modulus G (t) and the method of measuring the creep compliance J (t) are as shown in the following test examples. Further, "when a stress of 3000 Pa is applied to a pressure-sensitive adhesive" means a point of time when a stress is applied to a pressure-sensitive adhesive and the stress reaches 3000 Pa.

The pressure sensitive adhesive according to the present embodiment has a small value of the stress modulus or deformation fluctuation at the time of bending due to the small value of the modulus of elastic modulus change and the creep compliance variation value as described above, The deformation is likely to return to its original state, or the deformation itself is difficult to occur. Therefore, the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive can suppress the deformation of the pressure-sensitive adhesive layer even when the repeatedly bending device to which the pressure-sensitive adhesive layer is applied is repeatedly bent or in a state of being bent for a long period of time and released from the bending state. It is possible to suppress the hardening of the repeated bending device in a largely bent state and thus to mitigate the influence of the repeated bending of the repeated bending device due to the effect of being placed in a bent state. This effect is hereinafter referred to as " bending state relaxation effect of a repeated bending device ". As an index of the number of repeated bending, for example, 30,000 times is exemplified.

The multiplication value of the modulus of elasticity modulus value logg (t) and the creep compliance variation value logj (t) needs to be 3 or less, preferably 2.3 or less, and is preferably 1.8 or less, in view of the bending state relaxing effect of the above- And particularly preferably 0.88 or less. The lower limit value of the multiplication value is not particularly limited, but is usually 0.1 or more, and particularly preferably 0.2 or more.

In order to make it easy for the multiplication value of the modulus of elasticity modulus value logg (t) and the creep compliance variation value logj (t) to fall within the above range, the modulus of elasticity modulus value logg (t) is preferably 1.1 or less, Particularly preferably 0.75 or less, and more preferably 0.50 or less. The lower limit value of the modulus of modulus of modulus of elasticity is not particularly limited, but is preferably 0.10 or more, and particularly preferably 0.15 or more.

The upper limit of the maximum modulus of elasticity G (t) _max of the pressure-sensitive adhesive according to the present embodiment is preferably 1.0 MPa or less, particularly preferably 0.95 MPa or less, and more preferably 0.9 MPa or less. Since the upper limit value of the maximum relaxation modulus G (t) _max is the above, the relaxation modulus variation value? LogG (t) easily satisfies the above-described value. The lower limit value of the maximum relaxation modulus G (t) _max is not particularly limited, but is usually preferably 0.05 MPa or more, particularly preferably 0.10 MPa or more, and more preferably 0.15 MPa or more.

The minimum modulus of elasticity G (t) _min of the pressure sensitive adhesive according to the present embodiment is preferably 0.005 MPa or more, particularly preferably 0.01 MPa or more, and more preferably 0.02 MPa or more as the lower limit value. Since the lower limit value of the minimum relaxation modulus G (t) _min is as described above, the relaxation modulus variation value? LogG (t) easily satisfies the above-described value. The upper limit value of the minimum relaxation modulus G (t) _min is not particularly limited, but is usually preferably 0.50 MPa or less, particularly preferably 0.45 MPa or less, and more preferably 0.40 MPa or less.

On the other hand, in order to make it easy for the multiplication value of the modulus of elasticity modulus value logg (t) and the creep compliance variation value logj (t) to fall within the above range, the creep compliance variation value logj (t) is preferably 2.82 or less, More preferably 2.00 or less, and particularly preferably 1.95 or less. The lower limit value of the creep compliance variation value is not particularly limited, but is usually 1.00 or more, and particularly preferably 1.20 or more.

The minimum creep compliance J (t) of the pressure-sensitive adhesive according to the present embodiment _min is a minimum value, it is more preferable that it is particularly preferably not less than, and preferably not less than 1.0MPa ^{-1, -1} or more and 0.8MPa 0.5MPa ^-1. Since the lower limit value of the minimum creep compliance J (t) _min is as described above, the creep compliance variation value? LogJ (t) easily satisfies the above-described value. The upper limit value of the minimum creep compliance J (t) _min is not specifically limited, and usually, it is more preferable that not more than 5.0MPa ^-1 or less, and, 4.5MPa ^-1 and particularly preferably less than or equal to 4.0MPa ^-1.

In addition, the maximum creep compliance J (t) _max of the adhesive according to the present embodiment, as the upper limit value, preferably not more than 1000MPa ^-1, and particularly preferably less than or equal to ^-1 and 800MPa, more preferably 500MPa or lower ^-1, and 120MPa ^{- 1} or less. Since the upper limit value of the maximum creep compliance J (t) _max is the above, the creep compliance variation value? LogJ (t) easily meets the above-described value. The lower limit of the maximum creep compliance J (t) _max is not particularly limited, it is usually not less than 10MPa ^-1, and preferably, not less than 15MPa ^-1, particularly preferred, more preferably at least 20MPa ^-1.

The kind of the pressure sensitive adhesive according to the present embodiment is not particularly limited as long as the physical properties described above are satisfied, and may be any of acrylic pressure sensitive adhesives, polyester pressure sensitive adhesives, polyurethane pressure sensitive adhesives, rubber pressure sensitive adhesives, and silicone pressure sensitive adhesives. Further, the pressure-sensitive adhesive may be any of an emulsion type, a solvent type, and a solventless type, and may be a crosslinked type or a non-crosslinked type. Among them, an acrylic pressure-sensitive adhesive which is easy to satisfy the above-mentioned physical properties and excellent in pressure-sensitive properties and optical properties is preferable.

The acrylic pressure-sensitive adhesive may be one having an active energy ray curable property, an active energy ray non-curable property, a thermally crosslinkable property, a non-crosslinkable property or a combination thereof. However, , It is preferable that the active energy rays are non-curable. As the active energy ray non-curable acrylic pressure-sensitive adhesive, a crosslinking type is particularly preferable, and a thermally crosslinking type is more preferable.

The pressure sensitive adhesive according to the present embodiment is a pressure sensitive adhesive which is obtained by crosslinking a (meth) acrylic acid ester polymer (A) and a pressure sensitive adhesive composition containing a crosslinking agent (hereinafter sometimes referred to as "pressure sensitive adhesive composition P" desirable. With such a pressure-sensitive adhesive, it is easy to satisfy the physical properties described above, and good adhesion and predetermined cohesive force are obtained, so that durability is also excellent. In the present specification, the term "(meth) acrylic acid" means both of acrylic acid and methacrylic acid. The same is true of other similar terms. The term " polymer " also includes the concept of " copolymer ".

(1) Components of the sticky composition P

(1-1) Synthesis of (meth) acrylic acid ester polymer (A)

The (meth) acrylic acid ester polymer (A) preferably contains a (meth) acrylic acid alkyl ester and a monomer having a reactive functional group in the molecule (monomer having a reactive functional group) as a monomer unit constituting the polymer.

The (meth) acrylic acid ester polymer (A) can exhibit favorable tackiness by containing a (meth) acrylic acid alkyl ester as a monomer unit constituting the polymer. As the (meth) acrylic acid alkyl ester, a (meth) acrylic acid alkyl ester having an alkyl group of 1 to 20 carbon atoms is preferable. The alkyl group may be linear or branched or may have a cyclic structure.

As the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group, those containing a homopolymer having a glass transition temperature (Tg) of -40 ° C or less (hereinafter sometimes referred to as "low Tg alkyl acrylate") desirable. By including such low Tg alkyl acrylate as a constituent monomer unit, the flexibility of the obtained pressure sensitive adhesive can be improved.

Examples of the low Tg alkyl acrylate include n-butyl acrylate (Tg -55 占 폚), n-octyl acrylate (Tg -65 占 폚), isooctyl acrylate (Tg -58 占 폚), 2-ethylhexyl acrylate -70 ° C), isononyl acrylate (Tg -58 ° C), isodecyl acrylate (Tg -60 ° C), isodecyl methacrylate (Tg -41 ° C), n-lauryl methacrylate ), Tridecyl acrylate (Tg -55 占 폚), tridecyl methacrylate (Tg-40 占 폚), and the like. Among them, as the low Tg alkyl acrylate from the viewpoint of more effectively improving the flexibility, the Tg of the homopolymer is more preferably -45 占 폚 or lower, and particularly preferably -50 占 폚 or lower. Particularly, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) preferably contains a low Tg alkyl acrylate as a lower limit of 50 mass% or more as the monomer unit constituting the polymer, particularly preferably 55 mass% or more, More preferably 60 mass% or more. The glass transition temperature (Tg) of the (meth) acrylic acid ester polymer (A) can be easily set within the above-mentioned range by containing the low Tg alkyl acrylate in an amount of 50 mass% or more.

On the other hand, the (meth) acrylic acid ester polymer (A) preferably contains the low Tg alkyl acrylate as an upper limit of 99.9 mass% or less as a monomer unit constituting the polymer, particularly preferably 99 mass% or less By mass, and more preferably not more than 98% by mass. By containing 99.9 mass% or less of the low Tg alkyl acrylate, other monomer components (particularly, reactive functional group-containing monomers) can be introduced into the (meth) acrylic acid ester polymer (A).

(Meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a homopolymer (hereinafter sometimes referred to as "high Tg alkyl acrylate") having a glass transition temperature (Tg) of more than 0 ° C., . By containing such a high Tg alkyl acrylate as a constituent monomer unit, the value of the modulus of elastic modulus of the resulting pressure-sensitive adhesive may easily meet the above-described value.

When the (meth) acrylic acid ester polymer (A) contains a high Tg alkyl acrylate as a monomer unit constituting the polymer, the content thereof is preferably 5% by mass or more, particularly preferably 10% by mass or more, And more preferably 15 mass% or more. The content thereof is preferably 30 mass% or less, particularly preferably 25 mass% or less, and more preferably 20 mass% or less.

Examples of the high Tg alkyl acrylate include methyl acrylate (Tg 10 ° C), methyl methacrylate (Tg 105 ° C), ethyl methacrylate (Tg 65 ° C), n-butyl methacrylate Butyl acrylate (Tg of 107 占 폚), n-stearyl acrylate (Tg of 30 占 폚), n-stearyl methacrylate (Tg of 38 占 폚), acrylic acid Cyclohexyl methacrylate (Tg 66 ° C), benzyl methacrylate (Tg 54 ° C), isobornyl acrylate (Tg 94 ° C), isobornyl methacrylate (Tg 180 ° C) , Adamanthyl acrylate (Tg 115 ° C), and adamantyl methacrylate (Tg 141 ° C). Of these, methyl acrylate, methyl methacrylate and isobornyl acrylate are preferred from the viewpoint of cohesion. These may be used alone or in combination of two or more. The high-Tg alkyl acrylate does not contain the nitrogen atom-containing monomer described later.

The (meth) acrylic acid ester polymer (A) contains a reactive functional group-containing monomer as a monomer unit constituting the polymer, and reacts with a crosslinking agent (B) described later via a reactive functional group derived from the reactive functional group- As a result, a crosslinked structure (three-dimensional network structure) is formed, and a pressure-sensitive adhesive having a desired cohesive strength is obtained.

Examples of the reactive functional group-containing monomer containing the (meth) acrylic acid ester polymer (A) as a monomer unit constituting the polymer include monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomers), monomers having a carboxyl group in the molecule (carboxyl group- , Monomers having amino groups in the molecule (amino group-containing monomers), and the like. These reactive functional group-containing monomers may be used singly or in combination of two or more kinds.

Among the above-mentioned reactive functional group-containing monomer, a hydroxyl group-containing monomer and a carboxyl group-containing monomer are preferable, and a hydroxyl group-containing monomer is particularly preferable. The hydroxyl group-containing monomer has a relatively low glass transition temperature (Tg) as a homopolymer, so that the flexibility of the resulting (meth) acrylic acid ester polymer (A) tends to be kept high and the carboxyl group- A) can be increased.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (Meth) acrylate such as 3-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate are preferable from the viewpoint of the flexibility of the resulting (meth) acrylic acid ester polymer (A). These may be used alone or in combination of two or more.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. Among them, acrylic acid is preferable from the viewpoint of the adhesive force of the (meth) acrylic acid ester polymer (A) to be obtained. These may be used alone or in combination of two or more.

When the (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, the content of the hydroxyl group-containing monomer is preferably 0.1 mass% or more, particularly preferably 0.3 mass% or more Do. The content of the hydroxyl group-containing monomer is preferably 30 mass% or less, and particularly preferably 25 mass% or less. On the other hand, when the (meth) acrylic acid ester polymer (A) contains a monomer having a carboxyl group as a monomer unit constituting the polymer, the content of the monomer containing a carboxyl group is preferably 0.5% by mass or more, more preferably 1% Particularly preferred. The content of the carboxyl group-containing monomer is preferably 10 mass% or less, particularly preferably 7 mass% or less, and more preferably 5 mass% or less. The content of the hydroxyl group-containing monomer and the content of the carboxyl group-containing monomer are respectively as described above, the resulting (meth) acrylic acid ester polymer (A) has better flexibility and tackiness and the flexural state relaxation effect of the repeatedly- And is achieved at a high level.

The (meth) acrylic acid ester polymer (A) may contain a nitrogen atom-containing monomer as a monomer unit constituting the polymer. Examples of the nitrogen atom-containing monomer include monomers having an amino group, monomers having an amide group, monomers having a nitrogen-containing heterocyclic ring, and the like. Of these, monomers having a nitrogen-containing heterocyclic ring are preferable.

Examples of the monomer having a nitrogen-containing heterocyclic ring include N- (meth) acryloylmorpholine, N- vinyl-2-pyrrolidone, N- (meth) acryloylpyrrolidone, N- Acryloylpyridine, N- (meth) acryloylpyrrolidine, N- (meth) acryloyl aziridine, aziridinyl ethyl (meth) acrylate, 2- vinylpyridine, 4- Vinyl pyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide and the like. Of these, N- (meth) acryloylmorpholine exhibiting more excellent adhesion is preferable , N-acryloylmorpholine are particularly preferred. These may be used alone or in combination of two or more.

When the (meth) acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the content of the nitrogen atom-containing monomer is preferably 1% by mass or more, more preferably 3% Particularly preferred. The content of the nitrogen atom-containing monomer is preferably 20 mass% or less, particularly preferably 15 mass% or less, and more preferably 10 mass% or less.

The (meth) acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. As the other monomer, a monomer not containing a reactive functional group is preferable in order not to impair the above-mentioned action of the reactive functional group-containing monomer. Examples of such a monomer include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, vinyl acetate and styrene. These may be used alone or in combination of two or more.

The polymerization of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

The lower limit value of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 100,000 or more, particularly preferably 300,000 or more, more preferably 500,000 or more. If the lower limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is above, the durability of the pressure sensitive adhesive becomes better. In the present specification, the weight average molecular weight is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

The upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 1.5 million or less, particularly preferably 1.2 million or less, and more preferably 1 million or less. If the upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is above, the resulting pressure sensitive adhesive becomes more flexible.

In the sticky composition P, the (meth) acrylic acid ester polymer (A) may be used singly or in combination of two or more kinds.

(1-2) Crosslinking agent (B)

The crosslinking agent (B) crosslinks the (meth) acrylic acid ester polymer (A) to form a three-dimensional network structure by triggering heating or the like of the sticking composition P containing the crosslinking agent (B). As a result, the cohesive force of the obtained pressure sensitive adhesive is improved, and the pressure sensitive adhesive layer is excellent in durability.

The crosslinking agent (B) is not particularly limited as long as it reacts with the reactive group of the (meth) acrylic acid ester polymer (A), and examples thereof include isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, Based crosslinking agent, an aldehyde-based crosslinking agent, an oxazoline-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelating-type crosslinking agent, a metal salt-based crosslinking agent, and an ammonium salt-based crosslinking agent. Of the above, it is preferable to use an isocyanate-based crosslinking agent having excellent reactivity with the reactive functional group-containing monomer, particularly the hydroxyl group-containing monomer. The crosslinking agent (B) may be used alone or in combination of two or more.

The isocyanate crosslinking agent includes at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane di An alicyclic polyisocyanate such as isocyanate and the like, and an adduct which is a reaction product of a burette, isocyanurate and a low molecular active hydrogen-containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane, And the like. Among them, trimethylolpropane-modified aromatic polyisocyanates, especially trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferable from the viewpoint of reactivity with hydroxyl groups.

The content of the crosslinking agent (B) in the adhesive composition P is preferably at least 0.1 part by mass, particularly preferably at least 0.5 part by mass, more preferably at least 1.0 part by mass, relative to 100 parts by mass of the (meth) acrylic acid ester polymer (A) Is more preferable. The content is preferably 10 parts by mass or less, particularly preferably 8 parts by mass or less, and more preferably 5 parts by mass or less. When the content of the cross-linking agent (B) is in the above-mentioned range, the cohesive force of the obtained pressure-sensitive adhesive becomes appropriate, and the bending state of the repeated pressure-sensitive adhesive layer of the obtained pressure-

(1-3) Various additives

The adhesive composition P may contain various additives commonly used in acrylic pressure sensitive adhesives such as a silane coupling agent, an ultraviolet absorber, an antistatic agent, a tackifier, an antioxidant, a light stabilizer, a softener, a filler, Can be added. It is also assumed that the polymerization solvent or diluting solvent to be described later is not included in the additive constituting the adhesive composition P.

(2) Production of sticky composition P

The sticky composition P can be produced by preparing a (meth) acrylic acid ester polymer (A), mixing the obtained (meth) acrylic acid ester polymer (A) with the cross-linking agent (B) have.

The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method using a polymerization initiator if desired. As the polymerization solvent, for example, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone and the like may be used.

Examples of the polymerization initiator include an azo compound, an organic peroxide, and the like, and two or more types may be used in combination. Examples of the azo compound include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane 1-carbonyl Azobis (2,4-dimethyl-4-methoxy valeronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile) Azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile) Azobis [2- (2-imidazolin-2-yl) propane] and the like.

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate , t-butyl peroxyneodecanoate, t-butyl peroxypivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, and diacetyl peroxide.

In the polymerization step, a weight average molecular weight of the obtained polymer can be controlled by blending a chain transfer agent such as 2-mercaptoethanol.

(B) and, if desired, an additive and a diluting solvent are added to a solution of the (meth) acrylic acid ester polymer (A), and the mixture is sufficiently mixed with the solution of the (meth) acrylic acid ester polymer To obtain a diluted sticky composition P (coating solution).

In the case where precipitation occurs when any one of the above components is used in a solid phase or when it is mixed with other components in a non-diluted state, the component is solely dissolved or diluted in advance in a diluting solvent , And then mixed with other components.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as methanol, ethanol, propanol, Propanol and the like; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve solvents such as ethyl cellosolve Is used.

The concentration and viscosity of the coating solution thus prepared are not particularly limited and may be appropriately selected according to the circumstances. For example, it is diluted such that the concentration of the sticky composition P is 10 to 60 mass%. Addition of a diluting solvent is not a necessary condition for obtaining a coating solution, and a diluting solvent may not be added if the viscosity of the adhesive composition P is such as to be a coating. In this case, the adhesive composition P is a coating solution containing a polymerization solvent of the (meth) acrylic acid ester polymer (A) as it is as a diluting solvent.

(3) Production of pressure-sensitive adhesive

The pressure-sensitive adhesive according to the present embodiment is preferably formed by crosslinking the pressure-sensitive adhesive composition P. The crosslinking of the adhesive composition P can be usually carried out by a heat treatment. This heating treatment may also serve as a drying treatment for volatilizing a diluting solvent or the like from a coating film of the sticky composition P applied to a desired object.

The heating temperature for the heat treatment is preferably 50 to 150 占 폚, particularly preferably 70 to 120 占 폚. The heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes.

After the heat treatment, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, at 23 DEG C and 50% RH), if necessary. When the curing period is necessary, after the curing period, when the curing period is unnecessary, the pressure-sensitive adhesive is formed after the completion of the heat treatment.

(Meth) acrylic acid ester polymer (A) is sufficiently crosslinked through the crosslinking agent (B) by the above-mentioned heat treatment (and curing) to form a crosslinked structure, whereby a pressure sensitive adhesive is obtained. Such a pressure-sensitive adhesive has a predetermined cohesive force.

(4) Properties of adhesive

The storage elastic modulus (G ') of the pressure-sensitive adhesive according to the present embodiment at 25 캜 is preferably 0.01 MPa or more as a lower limit value. The upper limit of the storage elastic modulus (G ') is preferably 0.25 MPa or less, and particularly preferably 0.20 MPa or less.

The loss elastic modulus (G ") at 25 deg. C of the pressure sensitive adhesive according to the present embodiment is preferably 0.005 MPa or more, more preferably 0.01 MPa or more as the lower limit value. The upper limit value is preferably 0.1 MPa or less, and particularly preferably 0.08 MPa or less.

The loss tangent (tan?) Of the pressure-sensitive adhesive according to the present embodiment at 25 占 폚 is preferably 0.25 or more as the lower limit value, and particularly preferably 0.28 or more. The upper limit of the loss tangent (tan?) Is preferably 0.85 or less, and particularly preferably 0.80 or less.

When the storage elastic modulus (G '), the loss elastic modulus (G') and the loss tangent (tan delta) of the pressure sensitive adhesive according to the present embodiment are within the above ranges, the adhesive force to the bending member becomes good and the durability The measurement method of the storage elastic modulus (G '), the loss elastic modulus (G') and the loss tangent (tan?) Is as shown in the following test examples.

[Adhesive sheet]

The pressure-sensitive adhesive sheet according to the present embodiment has a pressure-sensitive adhesive layer for bonding one bendable member constituting the repeated bending device to another bendable member, and the pressure-sensitive adhesive layer is composed of the above-mentioned pressure-sensitive adhesive.

Fig. 1 shows a specific configuration as an example of the pressure-sensitive adhesive sheet according to the present embodiment.

1, the pressure-sensitive adhesive sheet 1 according to one embodiment is formed by two sheets of release sheets 12a and 12b and two sheets of release sheets 12a and 12b in contact with the release surfaces of the two release sheets 12a and 12b, And a pressure-sensitive adhesive layer 11 sandwiched between the release sheets 12a and 12b. The release surface of the release sheet in the present specification means a surface having release properties in the release sheet and includes both of the surface subjected to the release treatment and the surface exhibiting the release property without performing the release treatment.

(1) Components

(1-1) Pressure-sensitive adhesive layer

The pressure-sensitive adhesive layer (11) is composed of the pressure-sensitive adhesive according to the above-described embodiment, and is preferably composed of a pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition (P).

The thickness (the value measured in accordance with JIS K7130) of the pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheet 1 according to the present embodiment is preferably at least 2 mu m, particularly preferably at least 5 mu m, Mu m or more. If the lower limit of the thickness of the pressure-sensitive adhesive layer 11 is the above value, the desired adhesive force is easily exerted, and the occurrence of lifting and peeling at the time of repeated bending can be effectively suppressed. The upper limit of the thickness of the pressure-sensitive adhesive layer 11 is preferably 150 占 퐉 or less, more preferably 100 占 퐉 or less, particularly preferably 70 占 퐉 or less, and most preferably 50 占 퐉 or less. If the upper limit value of the thickness of the pressure-sensitive adhesive layer 11 is the above, it is possible to prevent the component constituting the pressure-sensitive adhesive or the pressure-sensitive adhesive from leaching out from the pressure-sensitive adhesive layer due to repeated bending. The pressure-sensitive adhesive layer 11 may be formed as a single layer, or may be formed by laminating a plurality of layers.

(1-2) Peeling sheet

The release sheets 12a and 12b protect the pressure-sensitive adhesive layer 11 by the use of the pressure-sensitive adhesive sheet 1 and are peeled off when the pressure-sensitive adhesive sheet 1 (pressure-sensitive adhesive layer 11) is used. In the pressure-sensitive adhesive sheet 1 according to the present embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

Examples of the release sheets 12a and 12b include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, (Meth) acrylic acid copolymer film, an ethylene / (meth) acrylic acid ester copolymer film, a polystyrene film, a poly (ethylene terephthalate) film, a polybutylene terephthalate film, a polyurethane film, an ethylene vinyl acetate film, an ionomer resin film, A carbon film, a polyimide film, a fluororesin film, or the like is used. These crosslinked films are also used. Further, these laminated films may be used.

It is preferable that a peeling treatment is performed on the peeling surface of the peeling sheets 12a and 12b (in particular, the surface in contact with the peeling layer 11). Examples of the releasing agent used in the peeling treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based releasing agents. It is also preferable that one of the release sheets 12a and 12b is a heavy-duty release sheet having a large stripping force and the other release sheet is a light-leakage release sheet having a small stripping force.

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

(2) Production of pressure-sensitive adhesive sheet

As a production example of the pressure-sensitive adhesive sheet 1, the case of using the pressure-sensitive adhesive composition P will be described. The application liquid of the adhesive composition P is applied to the release surface of one release sheet 12a (or 12b) and heat-treated to thermally crosslink the adhesive composition P to form a coating layer. Thereafter, The peeling sheet 12b (or 12a) is peeled off. When the curing period is required, the curing period is set so that the coating layer becomes the pressure-sensitive adhesive layer 11 when the curing period is unnecessary. Thus, the pressure-sensitive adhesive sheet (1) is obtained. The conditions of the heat treatment and curing are as described above.

As another production example of the adhesive sheet 1, a coating liquid of the adhesive composition P is applied to the release surface of one release sheet 12a and heat-treated to thermally crosslink the adhesive composition P to form a coating layer, Whereby a release sheet 12a with a coating layer is obtained. The application liquid of the adhesive composition P is applied to the release surface of the other release sheet 12b and heat-treated to thermally crosslink the adhesive composition P to form a release layer, (12b). Then, the peeling sheet 12a with a coating layer and the peeling sheet 12b with a coating layer are bonded so that both coating layers are in contact with each other. When the curing period is required, the curing period is provided, and when the curing period is unnecessary, the above-mentioned laminated coating layer becomes the pressure-sensitive adhesive layer (11). Thus, the pressure-sensitive adhesive sheet (1) is obtained. According to this manufacturing method, even if the pressure-sensitive adhesive layer 11 is relatively thick, it is possible to manufacture the pressure-sensitive adhesive layer 11 in a stable manner.

As a method of applying the application liquid of the sticky composition P, for example, a bar coat method, a knife coat method, a roll coat method, a blade coat method, a die coat method, a gravure coat method and the like can be used.

[Repetitive bending laminated member]

2, the repeated bending laminated member 2 according to the present embodiment includes a first bending member 21 (one bending member), a second bending member 22 (another bending member) And a pressure-sensitive adhesive layer (11) for bonding the first bendable member (21) and the second bendable member (22) to each other.

The pressure sensitive adhesive layer 11 in the repeatedly folded laminated member 2 is the pressure sensitive adhesive layer 11 of the pressure sensitive adhesive sheet 1 described above.

The repeated bending laminated member 2 is a repeated bending device itself or a member constituting a part of a repeated bending device. The repeated bending device is preferably a display capable of repeated bending (including bending), but is not limited thereto. As such a repetitive bending device, for example, an organic electroluminescence (organic EL) display, an electrophoretic display (electronic paper), a flexible printed substrate, a liquid crystal display using a plastic substrate (film) Or a touch panel.

The first bendable member 21 and the second bendable member 22 are members capable of repeated bending (including bending), and examples thereof include a cover film, a barrier film, a polarizing film, a polarizer, a retardation film, A transparent conductive film, a metal mesh film, a film sensor, a liquid crystal polymer film, a light-emitting polymer film, a film-like liquid crystal module, an organic EL module Organic EL film), and electronic paper module (film-like electronic paper).

Of the above, at least one of the first bending member 21 and the second bending member 22 is a display device capable of repeatedly bending, specifically, a liquid crystal polymer film, a light emitting polymer film, a film- Module (organic EL film), or an electronic paper module (film-like electronic paper).

The Young's modulus of each of the first bending member 21 and the second bending member 22 is preferably 0.1 to 10 GPa, more preferably 0.5 to 7 GPa, and even more preferably 1.0 to 5 GPa. The Young's modulus of the first bendable member 21 and the second bendable member 22 is in this range, so that it is easy to bend the bendable member repeatedly.

The first bendable member 21 and the second bendable member 22 preferably have a thickness of 5 to 3000 占 퐉, more preferably 10 to 1000 占 퐉, and further preferably 10 to 500 占 퐉. When the thicknesses of the first bendable member 21 and the second bendable member 22 are in this range, it is easy to bend the bendable member repeatedly.

In order to manufacture the repeatedly folded laminated member 2, for example, one of the release sheets 12a of the pressure-sensitive adhesive sheet 1 is peeled off and the exposed pressure-sensitive adhesive layer 11 of the pressure- And is attached to one side of the bendable member 21.

Thereafter, the other release sheet 12b is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 and the pressure-sensitive adhesive layer 11 and the second bendable member 22 exposed on the pressure- Thus, the repeatedly folded laminated member 2 is obtained. As another example, the order of knitting the first bending member 21 and the second bending member 22 may be changed.

[Repetitive bending device]

The repetitive bending device according to the present embodiment is provided with the bending laminated member 2 described above and may be composed of only the bending laminated member 2 or may be composed of one or more bending laminated members 2, And a flexible member may be provided. When laminating one cyclic laminate member 2 and another cyclic laminate member 2 or when laminating a bendable member different from the cyclic laminate member 2, the pressure-sensitive adhesive layer 1 of the above- (11).

Since the pressure-sensitive adhesive layer of the repetitive bending device according to the present embodiment is made of the above-mentioned pressure-sensitive adhesive, when the pressure-sensitive adhesive layer is repeatedly bent (for example, 30,000 times) or is placed in a long-term bending state , It is possible to suppress the hardening of the repeated bending device in a largely bent state after releasing the bending state from the bending state and to mitigate the influence of the repeated bending or the bending state. The bending state relaxation effect of the repeated bending device can be evaluated, for example, by the static bending deformation amount by the static bending test. As a bending test, there is a dynamic bending test in which a repeated bending device is repeated (for example, 30,000 times). However, since a static bending test is more stringent than a dynamic bending test in a repeated bending device, Good results are obtained in the dynamic bending test. Therefore, in confirming the bending state relaxing effect of the repeated bending device, it can be said that the static bending test is sufficient.

In the static bending test, a test piece having a size of 200 mm x 50 mm was used as a laminate comprising two pressure-sensitive adhesive layers (thickness: 12 m) sandwiched between two polyethylene terephthalate films (thickness: 12 m). As shown in Fig. 3, this test piece S is held for 24 hours in a bent state between two holding plates P made of two glass plates standing in an environment of 23 占 폚 and 50% RH . At this time, the distance between the two holding plates P is set to 6 mm (the bending diameter of the test piece S: 6 mm?), The approximately central portion of the long side (200 mm) of the test piece S becomes a bent portion, The test piece S is held so that the short side (50 mm) is located on the upper side. After the static bending test is performed, the test piece S is taken out from between the two holding plates P, and the test piece S is placed on a flat plate so that the convex direction of the bent portion is upward as shown in Fig. 4 . Then, immediately after the test, 30 minutes after the test and 24 hours after the test, the height h from the surface of the flat plate to the apex of the bent portion (deformation portion) is measured as the static bending deformation amount. The static bending deformation amount is a test result of the static bending test, and the bending state damping effect can be evaluated based on the static bending deformation amount.

The static bending deformation amount by the static bending test is preferably 5 mm or less immediately after the test, more preferably 3 mm or less, particularly preferably 2 mm or less, more preferably 1 mm or less, and 0.5 mm or less Most preferred. The lower limit value of the static bending deformation amount is preferably 0 mm.

The embodiments described above are described for the purpose of facilitating understanding of the present invention and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design modifications and equivalents falling within the technical scope of the present invention.

For example, one or both of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted, or a desired bending member may be laminated instead of the release sheets 12a and / or 12b.

(Example)

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]

1. Preparation of (meth) acrylic acid ester polymer (A)

60 parts by mass of butyl acrylate, 20 parts by mass of methyl acrylate and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized by a solution polymerization method to prepare a (meth) acrylic acid ester polymer (A). The molecular weight of the (meth) acrylic acid ester polymer (A) was measured by the method described later, and the weight average molecular weight (Mw) was 60,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylic acid ester polymer (A) obtained in the above Step 1 (solid content conversion value: the same in the following) and trimethylolpropane-modified tolylene diisocyanate (Toyo Khemsha, product name: BHS8515) And the mixture was sufficiently stirred and diluted with methyl ethyl ketone (MEK) to obtain a coating solution (solid content concentration: 30.0 mass%) of the adhesive composition.

3. Production of adhesive sheet

The coating solution of the sticky composition obtained in the above Step 2 was applied to the release treatment surface of a heavy-duty release sheet (LINTEC SHAZE, product name "SP-PET382150") in which one side of the polyethylene terephthalate film was stripped with a silicone- Trademark). Then, the coating layer was heat-treated at 90 DEG C for 1 minute to form a coating layer.

Next, the coated layer on the heavy-duty releasing sheet obtained above and the light-receding type releasing sheet (LINTEC SHAZE, product name " SP-PET381031 ") in which one surface of the polyethylene terephthalate film was peeled off with a silicone- Sensitive adhesive layer having a thickness of 12 占 퐉, that is, a pressure-sensitive adhesive sheet having a peeling releasing sheet / pressure-sensitive adhesive layer (having a thickness of 20 占 퐉) having a thickness of 12 占 퐉 was prepared by curing the release- : 12 占 퐉) / light-weight recycled release sheet. The thickness of the pressure-sensitive adhesive layer was measured using a static pressure thickness gauge (trade name: " PG-02 ") according to JIS K7130.

[Example 2]

47.8 parts by mass of 2-ethylhexyl acrylate, 47.8 parts by mass of n-butyl acrylate, 4 parts by mass of acrylic acid and 0.4 parts by mass of 2-hydroxypropyl acrylate were copolymerized by a solution polymerization method to prepare (meth) acrylic acid ester polymer did. The molecular weight of the (meth) acrylic acid ester polymer (A) was measured by the method described later, and the weight average molecular weight (Mw) was 60,000.

100 parts by mass of the (meth) acrylic acid ester polymer (A) obtained above and 3.75 parts by mass of trimethylolpropane-modified tolylene diisocyanate (Toyo Chemicals Co., Ltd., product name "BHS8515") as a crosslinking agent (B) To obtain a coating solution (solid content concentration: 30.0% by mass) of the adhesive composition. A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1, using the obtained coating solution of the adhesive composition.

[Example 3]

60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized by a solution polymerization method to prepare a (meth) acrylic acid ester polymer (A). The molecular weight of the (meth) acrylic acid ester polymer (A) was measured by the method described later, and the weight average molecular weight (Mw) was 60,000.

100 parts by mass of the (meth) acrylic acid ester polymer (A) obtained above and 1.88 parts by mass of trimethylolpropane-modified tolylene diisocyanate (Toyo Chemicals Co., Ltd., product name "BHS8515") as a crosslinking agent (B) To obtain a coating solution (solid concentration: 30.0% by mass) of the adhesive composition. A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1, using the obtained coating solution of the adhesive composition.

[Example 4]

65 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of N-acryloylmorpholine, 15 parts by mass of isobornyl acrylate and 15 parts by mass of 2-hydroxyethyl acrylate were copolymerized by solution polymerization to obtain (meth) acrylic acid ester To prepare a polymer (A). The molecular weight of the (meth) acrylic acid ester polymer (A) was measured by a method described later, and the weight average molecular weight (Mw) was 50,000.

100 parts by mass of the (meth) acrylic acid ester polymer (A) obtained above and 1.20 parts by mass of trimethylolpropane-modified tolylene diisocyanate (Toyo Chemicals Co., Ltd., product name "BHS8515") as a crosslinking agent (B) To obtain a coating solution (solid concentration: 30.0% by mass) of the adhesive composition. A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1, using the obtained coating solution of the adhesive composition.

[Example 5]

A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer (A) prepared in Example 3 was used and the blending amount of the crosslinking agent (B) was changed to 0.94 parts by mass.

[Example 6]

A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that the (meth) acrylic acid ester polymer (A) prepared in Example 1 was used and the blending amount of the crosslinking agent (B) was changed to 0.94 parts by mass.

[Example 7]

A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer (A) prepared in Example 1 was used and the blending amount of the crosslinking agent (B) was changed to 0.47 parts by mass.

[Example 8]

A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that the (meth) acrylic acid ester polymer (A) prepared in Example 4 was used and the blending amount of the crosslinking agent (B) was changed to 0.60 parts by mass.

[Example 9]

A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer (A) prepared in Example 3 was used and the blending amount of the crosslinking agent (B) was changed to 0.47 parts by mass.

[Example 10]

A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer (A) prepared in Example 3 was used and the compounding amount of the crosslinking agent (B) was changed to 0.23 parts by mass.

[Comparative Example 1]

A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer (A) prepared in Example 4 was used and the blending amount of the crosslinking agent (B) was changed to 0.30 parts by mass.

[Comparative Example 2]

, 15 parts by mass of an isobutylene-isoprene copolymer (Nippon Butylsulfate, product name "Butyl 365") and 3 parts by mass of a tackifier (Nippon Zeon Co., Ltd., product name "Kinton A100") were mixed, sufficiently stirred, diluted with toluene , A coating solution (solid content concentration: 15 mass%) of the adhesive composition as the butyl rubber was obtained. A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the coating solution of the obtained pressure-sensitive adhesive composition was used and the heat treatment temperature was set at 100 캜.

[Comparative Example 3]

A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer (A) prepared in Example 4 was used and the blending amount of the crosslinking agent (B) was changed to 0.15 parts by mass.

In Table 1, the composition of the (meth) acrylic acid ester polymer (A) and the amount of the crosslinking agent (B) in each of the Examples and Comparative Examples (the mass parts relative to 100 parts by mass of the (meth) acrylic acid ester polymer ). The abbreviations in Table 1 are as follows.

 BA: n-butyl acrylate

 MA: methyl acrylate

 HEA: 2-hydroxyethyl acrylate

 2EHA: 2-ethylhexyl acrylate

 AA: Acrylic acid

 2HPA: 2-hydroxypropyl acrylate

 MMA: methyl methacrylate

 ACMO: N-acryloylmorpholine

 IBXA: isobornyl acrylate

[Test Example 1] (Measurement of Modulus of Elastic Modulus)

A plurality of pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheet produced in Examples and Comparative Examples were laminated to obtain a laminate having a thickness of 0.5 mm. A cylindrical body (height: 0.5 mm) having a diameter of 8 mm was punched out from the obtained laminate of the pressure-sensitive adhesive layer, and this was used as a sample.

With respect to the sample, the pressure-sensitive adhesive was continuously deformed by 10% under the following conditions by using a viscoelasticity measuring apparatus (product name: "MCR302" manufactured by Anton Paar Co., Ltd.) according to JIS K7244-1 to obtain a modulus of elasticity G ) Were measured. From the measured results, the maximum relaxation modulus G (t) _max (MPa) for deriving hereinafter and with, the art maximum relaxation modulus G (t) then _max is measured and the minimum relaxation measure up after 3757 seconds modulus G (t) _min ( MPa).

 Measuring temperature: 25 ° C

 Measurement point: 1000 points (logarithm plot)

From the obtained maximum relaxation modulus G (t) _max (MPa) and the minimum modulus of elasticity G (t) _min (MPa), the modulus of elastic modulus change? LogG (t) was calculated based on the following formula (I). The results are shown in Table 1.

Logg (t) = logG (t) _max -logG (t) _min ... (I)

[Test Example 2] (Measurement of Creep Compliance)

A plurality of pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheet produced in Examples and Comparative Examples were laminated to obtain a laminate having a thickness of 0.5 mm. A cylindrical body (height: 0.5 mm) having a diameter of 8 mm was punched out from the obtained laminate of the pressure-sensitive adhesive layer, and this was used as a sample.

The creep compliance J (t) (MPa ^{- 1} ) of the sample was continuously measured by applying a stress of 3000 Pa under the following conditions using a viscoelasticity measuring apparatus (product name: "MCR302" manufactured by Anton paar). From the measurement result, the value when the stress of 3000 Pa is applied is defined as the minimum creep compliance J (t) _min (MPa ^-1 ), and the minimum creep compliance J (t) _min is measured until 3757 seconds after the minimum creep compliance J Maximum creep compliance J (t) _max (MPa ^-1 ) was derived.

 Measuring temperature: 25 ° C

 Measurement point: 1000 points (logarithm plot)

From the obtained minimum creep compliance J (t) _min (MPa ^-1 ) and maximum creep compliance J (t) _max (MPa ^-1 ), the creep compliance variation value? LogJ (t) is calculated did. The results are shown in Table 1.

LogJ (t) = logJ (t) _max- logJ (t) _min ... (II)

[Test Example 3] (Calculation of multiplication value)

A multiplication value (? LogG (t) x? LogJ (t)) between? LogG (t) obtained in Test Example 1 and? LogJ (t) obtained in Test Example 2 was calculated. The results are shown in Table 1.

[Test Example 4] (Measurement of dynamic modulus of elasticity)

A plurality of pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheet produced in Examples and Comparative Examples were laminated to obtain a laminate having a thickness of about 0.5 mm. A cylindrical body (height: 0.5 mm) having a diameter of 8 mm was punched out from the obtained laminate of the pressure-sensitive adhesive layer, and this was used as a sample.

The sample was subjected to dynamic viscoelasticity measurement under the following conditions using a viscoelasticity measuring apparatus (product name: "MCR302" manufactured by Anton paar) according to JIS K7244-1, and the storage elastic modulus (G ' (MPa), loss elastic modulus (G ") (MPa) and loss tangent (tan delta) were measured.

 Measuring frequency: 1Hz

 Measuring temperature range: -20 ~ 150 ℃

[Test Example 5] (Static bending test)

Sensitive release sheet was peeled off from the pressure-sensitive adhesive sheet produced in Examples and Comparative Examples under the environment of 23 占 폚 and 50% RH, and the exposed pressure-sensitive adhesive layer was laminated on a polyethylene terephthalate film (trade name: S10 Lumira, Thickness: 12 mu m). Next, the heavy-duty release sheet was peeled off, and the exposed pressure-sensitive adhesive layer was bonded to one side of another polyethylene terephthalate film (trade name: S10 Lumira, thickness: 12 μm). After pressurizing at 0.5 MPa and 50 캜 for 20 minutes with an autoclave made by Kurihara Seisakusho Co., Ltd., it was allowed to stand under the conditions of 23 캜 and 50% RH for 24 hours. The laminate composed of the thus obtained PET film / pressure-sensitive adhesive layer / PET film was cut into a size of 200 mm x 50 mm and used as a test piece.

As shown in Fig. 3, the test pieces thus obtained were maintained in a bent state in a state of 23 ° C and 50% RH for 24 hours between two holding plates (mutual distance: 6 mm) composed of two glass plates did. Immediately after the static bending test, the test piece is placed on a flat plate as shown in Fig. 4, and the height h from the flat plate surface to the apex portion of the bent portion (deformation portion) is set to the static bending deformation amount Respectively. Based on the measured static bending deformation amount, the static bending property was evaluated by the following criteria. In addition, whether or not the interface between the pressure-sensitive adhesive layer and the adherend had peeling-off was confirmed in the test piece after the test. The results are shown in Table 1.

 ?: Deformation amount is not more than 1 mm

 O: Deformation amount exceeding 1 mm, not more than 3 mm

 DELTA: Deformation amount exceeding 3 mm, not more than 6 mm

 X: Deformation amount exceeding 6 mm

[Table 1]

As can be seen from Table 1, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the Examples is excellent in the effect of easing the bending state when the two bendable members are laminated for a long time.

The present invention is suitable for bonding one bending member (for example, various films) constituting the repeated bending device to another bending member (for example, a display element).

1: Pressure sensitive adhesive sheet
11: Pressure-sensitive adhesive layer
12a, 12b: peeling sheet
2: Repetitive bending lamination member
21: first bendable member
22: second bendable member
S: Specimen
P: Retaining plate

Claims (9)

1. A pressure-sensitive adhesive for repeated bending devices for bonding one bendable member constituting a device to be bent repeatedly to another bendable member,
To conform to JIS K7244-1, the maximum value of the relaxation modulus which is measuring the pressure-sensitive adhesive when sikyeoteul 10% strain and the maximum relaxation modulus _{G (t) max (MPa)} , the art maximum relaxation modulus G (t) _max is measured And the minimum modulus of elasticity G (t) _min (MPa), which is a minimum value of the modulus of elasticity modulus measured therebetween, is calculated by the following equation (I) The variation value? LogG (t)
The creep compliance value measured when the stress of 3000 Pa is applied to the pressure-sensitive adhesive is defined as the minimum creep compliance J (t) _min (MPa ^-1 ), and after the minimum creep compliance J (t) _min is measured, (T) _max (MPa ^-1 ), and the creep compliance variation value ΔlogJ (t) calculated from the following formula (II) is used as the maximum creep compliance value measured between the maximum creep compliance and the maximum creep compliance. )Wow
Is less than or equal to 3
Wherein the pressure-sensitive adhesive is a pressure-sensitive adhesive.
Logg (t) = logG (t) _max -logG (t) _min ... (I)
LogJ (t) = logJ (t) _max- logJ (t) _min ... (II) The method according to claim 1,
Wherein the modulus of elastic modulus ΔlogG (t) is 1.1 or less. The method according to claim 1,
Wherein the creep compliance variation value logj (t) is 2.82 or less. The method according to claim 1,
Wherein the pressure-sensitive adhesive is a pressure-sensitive adhesive comprising a pressure-sensitive adhesive composition obtained by crosslinking a pressure-sensitive adhesive composition containing a (meth) acrylic acid ester polymer (A) and a crosslinking agent (B). 1. An adhesive sheet having a pressure-sensitive adhesive layer for bonding one bendable member constituting a device to be bent repeatedly to another bendable member,
Wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive for a bending device according to any one of claims 1 to 4
Wherein the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet. 6. The method of claim 5,
Wherein the pressure-sensitive adhesive sheet comprises two peeling sheets,
Wherein the pressure-sensitive adhesive layer is sandwiched between the peeling sheets so as to come into contact with the peeling surfaces of the two peeling sheets
Wherein the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet. One bending member and another bending member constituting the device to be repeatedly bent,
And a pressure-sensitive adhesive layer for bonding the one bendable member and the other bendable member to each other,
Wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to claim 5
Wherein the bending laminated member is a bending laminated member. 8. The method of claim 7,
Wherein at least one of the one bendable member and the other bendable member is a display element. A recursive bending device comprising the recurring bending laminated member according to claim 7.

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