KR102338567B1 - Adhesive sheet, optical member and display device using the same - Google Patents

Abstract

According to the present invention, the elongation at a thickness of 1000 μm is 1000% or more, and the indentation hardness (Asker C2 hardness) of the entire sheet is 30 to 60. It relates to an adhesive sheet having excellent bonding retention and durability with an adherend, an optical member including the same, and an image display device.

Description

Adhesive sheet, optical member and image display device including same {ADHESIVE SHEET, OPTICAL MEMBER AND DISPLAY DEVICE USING THE SAME}

The present invention relates to an adhesive sheet, an optical member including the same, and an image display device.

In the field of portable electronic devices, such as a mobile phone and a portable information terminal device, adhesive is used for fixing between various members. As the adhesive, optically clear resin (OCR), which is a liquid adhesive, and optically clear adhesive (OCA), which is a sheet-type adhesive, are used.

In particular, OCR-type pressure-sensitive adhesives have been used in the manufacture of various electronic devices because they are easy to remove using ethanol, etc. In the case of an adhesive, there is a problem that the adhesive strength is insufficient to be applied to a flexible image display device, which is recently in the spotlight.

In this regard, Korean Patent Laid-Open No. 10-2016-0117866 discloses a (meth)acrylic copolymer and a (meth)acrylic monomer having a weight average molecular weight of 600,000 g/mol to 1.5 million g/mol, and elongation after curing Although it has been described with respect to the pressure-sensitive adhesive composition of 500% or more, it has a problem of insufficient durability to be applied to a flexible image display device.

In addition, Korean Patent Laid-Open No. 10-2012-0138732 discloses that one or more (meth)acrylic acid ester-based copolymers are used as a base resin, and the indentation hardness (Aster C2 hardness) of the entire sheet is 10 to 80. Although described with respect to a double-sided pressure-sensitive adhesive sheet, this has a problem in that it is not efficient because the process is complicated with a structure including two or more pressure-sensitive adhesive layers.

Republic of Korea Patent Publication No. 10-2016-0117866 (2016.10.11.) Republic of Korea Patent Publication No. 10-2012-0138732 (2012.12.26.)

An object of the present invention is to provide an adhesive sheet having excellent durability (heat resistance, moisture and heat resistance), holding power and elongation, and an optical member and an image display device including the same to solve the above problems.

The pressure-sensitive adhesive sheet of the present invention for achieving the above object is characterized in that the elongation at a thickness of 1000 μm is 1000% or more, and the indentation hardness (Asker C2 hardness) of the entire sheet is 30 to 60.

In addition, the optical member of the present invention is characterized in that it includes the above-described pressure-sensitive adhesive sheet.

In addition, the image display apparatus of the present invention is characterized in that it includes the above-described optical member.

The pressure-sensitive adhesive sheet of the present invention has excellent adhesive strength and thus not only has excellent holding power when bonding with an adherend, but also has excellent durability (heat resistance, heat-and-moisture resistance) and elongation, so that it is easy to maintain bonding with a flexible adherend.

Moreover, the optical member of this invention has the same advantage as the above by including the above-mentioned adhesive sheet.

In addition, the image display apparatus of the present invention has the same advantages as described above by including the above-described optical member.

In the present invention, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

In the present invention, "(meth)acryl" means acryl and/or methacrylic.

In the present invention, "elongation" means a value measured by the ASTM D368 method for a 1000 μm-thick adhesive film specimen.

Hereinafter, the present invention will be described in more detail.

<Adhesive sheet>

The pressure-sensitive adhesive sheet according to an embodiment of the present invention has an elongation of 1000% or more at a thickness of 1000 μm, and an indentation hardness of the entire sheet (Asker C2 hardness) of 30 to 60, so that not only adhesive strength but also heat resistance, heat resistance, etc. It has excellent durability and elongation, so it has the advantage of excellent bonding retention with a flexible adherend.

The indentation hardness is measured by stacking a plurality of the adhesive sheets of the present invention to a thickness of 6mm±0.3mm, and vertically pressing a measuring terminal with a depth of 2.5mm using an Asker hardness tester at a press fit weight of 1000g and an indentation speed of 3mm/min. do.

At this time, in the case of measuring a plurality of the pressure-sensitive adhesive sheets with a thickness of 6 mm ± 0.3 mm, by making the thickness at the time of measurement in the above range, the influence of the thickness is eliminated, and the original indentation hardness of the member can be compared and measured. because there is

The indentation hardness of the pressure-sensitive adhesive sheet of the present invention is characterized in that it is 30 to 60. When the indentation hardness is less than the above range, it is relieved from the deformation stress caused by indentation, but it is too flexible and thus unexpected deformation is easy to occur, so workability and storage There is a problem of poor stability. On the other hand, if the indentation hardness exceeds the above range, it may be too hard to cause a problem of poor harvestability to the adherend, and durability such as heat resistance and heat and moisture resistance may be reduced, and step absorption may be reduced, By controlling the indentation hardness within the range suggested by the present invention, it is possible to maintain good appearance at the time of bonding to an adherend while achieving both excellent workability and harvestability.

The pressure-sensitive adhesive sheet of the present invention may be manufactured using any pressure-sensitive adhesive composition as long as it can satisfy the above conditions, but according to an embodiment of the present invention, it may include a cured product of the pressure-sensitive adhesive composition to be described later. have.

adhesive composition

Acrylic polymer (A)

According to an embodiment of the present invention, the pressure-sensitive adhesive composition is a repeating unit derived from an acrylic monomer (a1) containing a _{C 6} to C _{20 linear, branched or alicyclic alkyl group;} and a repeating unit derived from the acrylamide monomer (a2); and may include a polymerized acrylic polymer (A).

The acrylic monomer (a1) is present in the acrylic polymer and can improve wettability when bonding to an adherend, thereby improving adhesion and thus bonding retention.

The acrylic monomer (a1) may contain a C ₆ to C ₂₀ straight chain, branched chain or alicyclic alkyl group as described above, and specifically, the acrylic monomer (a1) is a straight chain, branched chain or It may be an alkyl (meth)acrylate containing an alicyclic alkyl group.

The alkyl (meth) acrylate having the straight-chain 　 or branched alkyl group is not particularly limited, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylic. rate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, Hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) ) acrylate, isobornyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate , tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate and eico A seal (meth)acrylate etc. are mentioned.

The alkyl (meth) acrylate containing the alicyclic alkyl group is trimethylcyclohexyl acrylate, t-butyl cyclohexyl acrylate, dicyclopentadiene (meth) acrylate, trimethylcyclohexyl methacrylate, cyclohexyl Methacrylate, isobornyl methacrylate, 2-ethylhexyl methacrylate, tetrahydrofurfuryl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, 4-t-butyl cyclohexyl methacrylate and the like, but is not limited thereto.

According to one embodiment of the present invention, the repeating unit derived from the acrylic monomer (a1) is 60 to 95% by weight, preferably 70 to 95% by weight, more preferably based on 100% by weight of the total acrylic polymer (A) may be included in 80 to 95% by weight.

According to an embodiment of the present invention, the amide monomer (a2) may include at least one selected from the group consisting of compounds represented by the following Chemical Formulas 1 and 2.

[Formula 1]

[Formula 2]

(In Formulas 1 and 2,

R ₁ is each independently hydrogen or a methyl group,

R ₂ is each independently a C ₁ to C ₁₀ linear or branched hydrocarbon group.)

Specifically, the C ₁ to C ₁₀ linear hydrocarbon group may include, but is not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl.

The C ₁ to C ₁₀ branched chain hydrocarbon group is specifically, methylethyl, dimethylmethyl, 2-methylpropyl, 2,2-dimethylpropyl, 2-methylbutyl, 2,3-dimethylbutyl, 2,2-dimethylbutyl , 2-ethyl-2-methylpropyl, 2-methylpentyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 2,3,4-trimethylpentyl, 2-ethyl-2 -Methylpentyl group, 2-ethylhexyl group, etc. are mentioned. The number of carbon atoms in the branched chain hydrocarbon group may be _{specifically C 2} to C _10.

As such, when the amide monomer (a2) contains any one of the compounds represented by Chemical Formulas 1 and 2, since the acrylic polymer (A) contains an amide group instead of a conventional acid group (-COOH), metal wiring, metal electrode layer Excellent cohesive force may be imparted through intramolecular hydrogen bonding and chelating bonding with ions remaining in an adherend such as metal ions or glass remaining in the sheet, without causing corrosion on the back.

According to an embodiment of the present invention, the repeating unit derived from the amide monomer (a2) may be 5 to 20% by weight, specifically 7 to 15% by weight, based on 100% by weight of the total acrylic polymer (A). have.

When the amide monomer is included within the above range, there is an advantage in that it is possible to manufacture an adhesive sheet having excellent durability.

According to an embodiment of the present invention, the acrylic polymer (A) may further contain more than 0 to 10% by weight or less of the polar monomer (a3) based on 100% by weight of the total acrylic polymer (A). When the polar monomer (a3) is included within the above range, there is an advantage that cohesive force is improved, so that durability can be improved, and adhesive force can also be improved.

The polar monomer contains a monomer containing a polymerizable unsaturated bond together with at least one polar group, and specifically, (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and acids thereof carboxyl group-containing monomers such as anhydrides (eg, acid anhydride-containing monomers such as maleic anhydride and itaconic anhydride); (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 4-hydroxybutyl, (meth)acrylic acid 5-hydroxypentyl, (meth)acrylic acid 6-hydroxyhexyl; Hydroxyl group (hydroxyl group) containing monomers, such as vinyl alcohol and allyl alcohol; (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxy methyl (meth)acrylamide, N-butoxy methyl (meth)acrylamide, N -amide group containing monomers, such as hydroxyethyl (meth)acrylamide; amino group-containing monomers such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; Epoxy group-containing monomers, such as (meth)acrylic-acid glycidyl and (meth)acrylic-acid methylglycidyl; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; Heterocyclic-containing vinyl monomers such as N-vinyl-2-pyrrolidone, (meth)acryloylmorpholine, N-vinylpiperidone, N-vinylpiperazine, N-vinylpyrrole, and N-vinylimidazole ; Sulfonic acid group-containing monomers, such as sodium vinylsulfonate; phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; imide group-containing monomers such as cyclohexyl maleimide and isopropyl maleimide; and isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate, and preferably a polar monomer containing a hydroxyl group, but is not limited thereto.

According to one embodiment of the present invention, the above-described acrylic polymer (A) may have a weight average molecular weight of 300,000 to 700,000, specifically 400,000 to 700,000. When the weight average molecular weight is included within the above range, there is an advantage that the viscosity can be adjusted to an advantageous process in the process, and there is an advantage that physical properties such as hardness can be improved.

The aforementioned acrylic polymer (A) may be formed by adding a photopolymerization initiator to be described later to the aforementioned acrylic monomer (a1), acrylamide monomer (a2), and polar monomer (a3) to polymerize part or all of it, such as The mixture may be referred to as acrylic syrup. The specific content of the photoinitiator included in this case is the same as the photoinitiator to be described later, and the same kind or different kinds may be used.

According to an embodiment of the present invention, the pressure-sensitive adhesive composition may further include an acrylic monomer (B) in addition to the above-described acrylic polymer (A).

The acrylic monomer (B) is included as a separate component from the acrylic monomer (a2) for polymerization of the acrylic polymer, and the types of the acrylic monomers (B and a2) may be the same or different from each other. At this time, for specific details of the acrylic monomer (B) that may be additionally included, you may refer to the above-described acrylic monomer (a2).

As such, when the acrylic monomer (B) is further included, the amount of the acrylic polymer (A) is 10 to 30 parts by weight based on 100 parts by weight of the total of the acrylic polymer (A) and the acrylic monomer (B) included together. Parts, the acrylic monomer (B) may be included in an amount of 70 to 90 parts by weight. As such, when the content of the acrylic polymer (A) and the acrylic monomer (B) is included within the above range, there is an advantage that not only the photocuring rate of the pressure-sensitive adhesive composition including them is improved, but also the elongation rate can be improved.

As such, when the pressure-sensitive adhesive sheet of the present invention includes the cured product of the above-described pressure-sensitive adhesive composition, there is an advantage that the elongation and indentation hardness can be adjusted within the ranges presented in the present invention.

According to an embodiment of the present invention, the pressure-sensitive adhesive composition may further include at least one selected from the group consisting of a photopolymerization initiator and an additive.

light curing initiator

The photopolymerization initiator serves to cure the pressure-sensitive adhesive composition including the same, and as long as it is used as a photopolymerization initiator in the art, it can be used without particular limitation, and is not particularly limited in the present invention.

Specifically, benzoin ether-based photopolymerization initiator, acetophenone-based photoinitiator, α-ketol-based photopolymerization initiator, aromatic sulfonyl chloride-based photopolymerization initiator, photoactive oxime-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzyl-based photopolymerization initiator, benzophene A non-type photoinitiator, a ketal type photoinitiator, a thioxanthone type photoinitiator, an acylphosphine oxide type photoinitiator, etc. are mentioned.

Examples of the benzoin ether-based photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2- diphenylethan-1-one [manufactured by BASF, trade name: Irgacure 651], anisolemethyl ether, and the like, but are not limited thereto.

Examples of the acetophenone-based photopolymerization initiator include 1-hydroxycyclohexylphenylketone [manufactured by BASF, trade name: Irgacure 184], 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1 -[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one [manufactured by BASF, trade name: Irgacure 2959], 2-hydroxy-2 -methyl-1-phenyl-propan-1-one [manufactured by BASF, trade name: Darocure-1173], methoxyacetophenone, and the like. Examples of the α-ketol-based photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)-phenyl]-2-hydroxy-2-methylpropane- 1-one, and the like, but are not limited thereto.

Examples of the aromatic sulfonyl chloride-based photopolymerization initiator include, but are not limited to, 2-naphthalenesulfonyl chloride.

Examples of the photoactive oxime-based photopolymerization initiator include, but are not limited to, 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime.

The benzoin-based photopolymerization initiator includes, for example, benzoin, and the benzyl-based photopolymerization initiator includes, for example, benzyl, and the benzophenone-based photopolymerization initiator includes, for example, benzophenone and benzoyl. benzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinyl benzophenone, α-hydroxycyclohexylphenyl ketone, and the like, but is not limited thereto.

The said ketal-type photoinitiator is, for example, benzyl dimethyl ketal, etc. are mentioned, The said thioxanthone-type photoinitiator is, for example, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2 , 4-dimethyl thioxanthone, isopropyl thioxanthone, 2,4-dichlorothioxanthone, 2,4-diethyl thioxanthone, isopropyl thioxanthone, 2,4-diisopropyl thioxanthone, and dodecyl thioxanthone, but is not limited thereto.

Examples of the acylphosphine-based photopolymerization initiator include bis(2,6-dimethoxybenzoyl)phenyl phosphine oxide, bis(2,6-dimethoxybenzoyl)(2,4,4-trimethylpentyl)phosphine oxide, Bis(2,6-dimethoxybenzoyl)-n-butylphosphine oxide, bis(2,6-dimethoxybenzoyl)-(2-methylpropan-1-yl)phosphine oxide, bis(2,6-dimethy Toxybenzoyl)-(1-methylpropan-1-yl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-t-butylphosphineoxide, bis(2,6-dimethoxybenzoyl)cyclohexyl phosphine oxide Cid, bis(2,6-dimethoxybenzoyl) octyl phosphineoxide, bis(2-methoxybenzoyl)(2-methylpropan-1-yl)phosphineoxide, bis(2-methoxybenzoyl)(1- Methylpropan-1-yl) phosphineoxide, bis(2,6-diethoxybenzoyl)(2-methylpropan-1-yl)phosphineoxide, bis(2,6-diethoxybenzoyl)(1-methylpropane -1-yl) phosphine oxide, bis (2,6-dibutoxybenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2,4-dimethoxybenzoyl) (2-methylpropane-1 -yl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) (2,4-dipentoxy phenyl) phosphine oxide, bis (2,6-dimethoxybenzoyl) benzyl phosphine oxide, bis (2, 6-dimethoxybenzoyl)-2-phenylpropyl phosphineoxide, bis(2,6-dimethoxybenzoyl)-2-phenylethyl phosphineoxide, bis(2,6-dimethoxybenzoyl)benzyl phosphineoxide, bis (2,6-dimethoxybenzoyl)-2-phenylpropyl phosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylethyl phosphine oxide, 2,6-dimethoxybenzoylbenzylbutyl phosphine oxide, 2,6-dimethoxybenzoylbenzyloctyl phosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,5-diisopropylphenyl phosphine oxide, bis(2,4,6-trimethylbenzoyl)-2 -Methylphenyl phosphineoxide, bis(2,4,6-trimethylbenzoyl)-4-methylphenyl phosphineoxide, bis(2,4,6-trimethylbenzoyl)-2,5-diethylphenyl phosphineoxide, bis( 2,4,6-trimethylbenzoyl)-2,3,5,6-tetramethylphenyl phosphineoxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxyphenyl phosphineoxide , 2,4,6-trimethylbenzoyl Diphenyl phosphineoxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphineoxide, bis(2,4,6-trimethylbenzoyl)isobutyl phosphineoxide, 2,6- Dimethoxybenzoyl-2,4,6-trimethylbenzoyl-n-butyl phosphineoxide, bis(2,4,6-trimethylbenzoyl)phenyl phosphineoxide, bis(2,4,6-trimethylbenzoyl)-2, 4-dibutoxyphenyl phosphine oxide, 1,10-bis[bis(2,4,6-trimethylbenzoyl)phosphineoxide]decane, tri(2-methylbenzoyl)phosphine oxide, and the like, but are limited thereto. it is not going to be

The content of the photoinitiator may be included in an amount of 0.01 to 3 parts by weight, specifically 0.5 to 2 parts by weight, based on 100 parts by weight of the total acrylic syrup included therewith. When the content of the photopolymerization initiator is included within the above range, the polymerization reaction can be sufficiently performed, and a decrease in the molecular weight of the resulting polymer can be suppressed, thereby securing the cohesive force of the formed pressure-sensitive adhesive layer.

additive

The additive may be used without particular limitation according to the purpose of the user within the range that can achieve the object of the present invention, and specifically, a crosslinking accelerator, a silane coupling agent, an anti-aging agent, a colorant (pigment, dye, etc.), a UV absorber, antioxidants, chain transfer agents, plasticizers, softeners, antistatic agents, solvents, and the like, but are not limited thereto, and these may be used alone or in combination of two or more.

The thickness of the pressure-sensitive adhesive sheet of the present invention may be 50 to 200㎛, specifically 100 to 150㎛.

The pressure-sensitive adhesive sheet may have excellent durability and processability within the suggested thickness range, and may have excellent transparency of the pressure-sensitive adhesive sheet.

The pressure-sensitive adhesive sheet according to an embodiment of the present invention has an elongation of 1000% or more at a thickness of 1000 μm, and an indentation hardness of the entire sheet (Asker C2 hardness) of 30 to 60, so that not only adhesive strength but also durability and elongation are excellent Therefore, there is an advantage in that it has excellent bonding retention with a flexible adherend.

< optical member >

Another aspect of the present invention is an optical member including the adhesive sheet described above.

By including the adhesive sheet of the present invention, the optical member has an advantage of being easy to apply to a flexible optical member because it has excellent durability and elongation.

Specifically, the optical member may include, but is not limited to, a polarizing plate, a retardation plate, an optical film for a plasma display, a conductive film for a touch panel, a reflective sheet, and a brightness enhancing film, and other optical members may also be applied do.

<Image display device>

Another aspect of the present invention is an image display device including the above-described optical member.

Since the image display device includes the above-described optical member, both durability and elongation are excellent, so that it is easy to apply to a flexible image display.

The image display device is not particularly limited, and for example, a liquid crystal display device (LCD), a field emission display device (FED), a plasma display device (PDP), an organic electroluminescent device (OLED), and the like may be mentioned.

Hereinafter, preferred examples are presented to help the understanding of the present invention, but the following examples are merely illustrative of the present invention, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention. , it is natural that such variations and modifications fall within the scope of the appended claims. In the following Examples and Comparative Examples, "%" and "part" indicating the content are by weight unless otherwise specified.

production example : ( meta ) acrylate production of syrup

production example One

45% by weight of 2-ethylhexyl acrylate (2-EHA) monomer, 35% by weight of isobornyl acrylate (IBOA) monomer, N-part After adding a monomer mixture consisting of 15% by weight of toxymethylacrylamide (NBMAA) monomer and 5% by weight of 5-hydroxypentyl acrylate (5-HPA) monomer, nitrogen gas was purged for 1 hour to remove oxygen. , was maintained at 80 °C. After uniformly mixing the monomer mixture, when the total weight of the monomer mixture was 100 parts by weight, 0.5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone as a photoinitiator was added. After stirring, UV lamp (10mW) was irradiated to prepare (meth)acrylate syrup having a polymer conversion rate of 25%.

production example 2 to 7

It was carried out in the same manner as in Preparation Example 1, but (meth)acrylate syrup was prepared with the composition shown in Table 1 below.

The weight average molecular weight and molecular weight distribution of (meth)acrylate syrup were measured using GPC under the following conditions. A standard polystyrene of Agilent system was used for preparation of a calibration curve, and the measurement result was converted.

<Weight average molecular weight measurement conditions>

Meter: Agilent GPC (Agilent 1200 series, USA)

Column: Connect 2 PL Mixed B

Column temperature: 40°C

Eluent: tetrahydrofuran

Flow rate: 1.0 mL/min

Concentration: ~1mg/mL (100 μL injection)

division (meth)acrylate monomer (weight %) photoinitiator
(parts by weight) polymer
conversion rate
(%) weight average
Molecular Weight
(Unit: million) 2-EHA IBOA NBMAA 5-HPA Preparation Example 1 (A1) 45 35 15 5 0.5 25 43 Preparation 2 (A2) 50 33 10 7 0.5 25 58 Production Example 3 (A3) 50 35 5 10 0.5 26 68 Preparation 4 (A4) 45 30 25 - 0.5 27 25 2-EHA: 2-ethylhexyl acrylate
IBOA: isobornyl acrylate
NBMAA: N-butoxymethylacrylamide
5-HPA: 5-hydroxypentyl acrylate
Photoinitiator: 1-hydroxy cyclohexylphenyl ketone

Example 1 to 4 and comparative example One.

A pressure-sensitive adhesive composition was prepared by mixing the contents of the (meth)acrylate syrup and the photoinitiator of the Preparation Example in the composition shown in Table 2 below.

The pressure-sensitive adhesive composition prepared above is applied to a thickness of 150 μm on a release film coated with a silicone release agent, and a release film is bonded thereon to prepare an adhesive sheet, followed by UV (accumulated light amount 400 mJ/cm ² , illuminance 1.8 mW/ cm ² , based on UVV) to prepare a sheet.

Experimental example One: elongation measurement

Peel the release film on one side of each pressure-sensitive adhesive sheet prepared in Examples and Comparative Examples, and sequentially stack the exposed pressure-sensitive adhesive sheets on top of each other until the thickness of the plurality of pressure-sensitive adhesive sheets becomes 1000 μm±10 μm, It was left to stand for 24 hours in 23 degreeC and the atmosphere of 50% of humidity. After that, the pressure-sensitive adhesive sheet laminated with a plurality of the pressure-sensitive adhesive layers is cut to 10 mm (width) × 60 mm (length), the release film laminated on the outermost layer of the laminate is peeled off, and a tensile tester (Dongil Shimadzu, Autograph) The sample was set so that the sample measurement range was 10 mm (width) × 10 mm (length), and it was stretched until fracture at a tensile rate of 500 mm/min in an environment of 23° C. and 50% RH, and the elongation (%) was measured.

Experimental example 2: indentation hardness measurement

The release film on one side of the pressure-sensitive adhesive sheet prepared in Examples and Comparative Examples was peeled off, the exposed pressure-sensitive adhesive surface was sequentially overlapped, and a plurality of pressure-sensitive adhesive sheets were laminated until the thickness became 6 mm±0.3 mm. Then, with respect to the exposed adhesive surface of the laminated adhesive sheet, the tip terminal of the Asker C2L hardness tester was pressed vertically downward at a weight of 1000 g and a press-in speed of 3 mm/sec using a static pressure weighting machine CL150, and the indentation hardness was measured.

Experimental example 3: Durability (heat resistance, moisture heat resistance ) evaluation

The adhesive sheet prepared by peeling the release film on one side of the pressure-sensitive adhesive sheet prepared in Examples and Comparative Examples and corona-treating and bonding the 40 μm cycloolefin (COP)-based film and the pressure-sensitive adhesive surface was cut to a size of 90 mm × 170 mm. After peeling the release film attached to the other side, it was attached to a glass substrate (110 mm × 190 mm × 0.7 mm) to prepare a specimen. At this time, the applied pressure was 5 kg/cm ^{2 ,} and a clean room operation was performed to prevent bubbles or foreign substances from being generated.

The heat resistance property was observed whether bubbles or peeling occurred after leaving it at 80 °C for 500 hours. was observed. The evaluation criteria are as follows, and the results are described in Table 2 below.

<Evaluation criteria>

ⓞ: No air bubbles or partial peeling

○: Less than 5 bubbles or partial peeling

△: 5 or more, less than 10 bubbles or partial peeling

×: 10 or more air bubbles or partial peeling

Example comparative example One 2 3 One (meth)acrylate syrup
(parts by weight) Kinds A1 A2 A3 A4 content 100 100 100 100 photoinitiator
(parts by weight) ¹⁾ 0.5 0.5 0.5 0.5 elongation
(%) 1084 1350 1604 860 indentation hardness
(g/m2·24h) 57 41 49 68 durability heat resistance ○ ⓞ ⓞ × moisture heat resistance ⓞ ⓞ ⓞ × 1) 2,2-dimethoxy-1,2-diphenylethanone

Referring to Table 2, when the range of elongation and indentation hardness suggested in the present invention is satisfied (Examples 1 to 3), heat resistance and heat-and-moisture resistance are better than Comparative Example 1 out of the range of elongation and indentation hardness of the present invention All were confirmed to be excellent.

Claims (12)

An adhesive sheet, characterized in that the elongation at a thickness of 1000 μm is 1000% or more, and the indentation hardness (Asker C2 hardness) of the entire sheet is 30 to 60,
The pressure-sensitive adhesive sheet includes a cured product of the pressure-sensitive adhesive composition,
The pressure-sensitive adhesive composition may include a repeating unit derived from an acrylic monomer (a1) containing a _{C 6} to C _{20 linear, branched or alicyclic alkyl group;} and a repeating unit derived from an acrylamide monomer (a2); and a polymerized acrylic polymer (A). delete delete According to claim 1,
The weight average molecular weight of the acrylic polymer (A) is an adhesive sheet, characterized in that 300,000 to 700,000. According to claim 1,
The acrylamide monomer (a2) is a pressure-sensitive adhesive sheet comprising at least one selected from the group consisting of compounds represented by the following Chemical Formulas 1 and 2:
[Formula 1]

[Formula 2]

In Formulas 1 and 2,
R ₁ is each independently hydrogen or a methyl group,
R ₂ is each independently a C ₁ to C ₁₀ linear or branched hydrocarbon group. According to claim 1,
With respect to 100% by weight of the total acrylic polymer (A),
The repeating unit derived from the acrylic monomer (a1) is included in an amount of 80 to 95% by weight,
The adhesive sheet, characterized in that the repeating unit derived from the acrylamide monomer (a2) is contained in 5 to 20% by weight. According to claim 1,
The acrylic polymer (A) is based on 100% by weight of the total acrylic polymer (A),
The adhesive sheet, characterized in that it further comprises more than 0 and 10% by weight or less of the polar monomer (a3). According to claim 1,
The pressure-sensitive adhesive composition further comprises an acrylic monomer (B). 9. The method of claim 8,
Based on 100 parts by weight of the total of the acrylic polymer (A) and the acrylic monomer (B),
The acrylic polymer (A) is included in an amount of 10 to 30 parts by weight,
The adhesive sheet, characterized in that the acrylic monomer (B) is included in an amount of 70 to 90 parts by weight. According to claim 1,
The pressure-sensitive adhesive composition further comprises one or more selected from the group consisting of a photopolymerization initiator and additives. An optical member comprising the adhesive sheet of any one of claims 1 and 4 to 10. An image display device comprising the optical member of claim 11 .