KR102449011B1 - Adhesive layer, optical member and display device using the same - Google Patents

Abstract

The present invention is characterized in that the elastic modulus at 25 ℃ is 1.0 × 10 ⁵ to 1.5 × 10 ⁶ Pa, and the adhesion is 0.15 MPa or less under the conditions of -110 ℃ or less, so that it can be applied to a flexible optical member due to excellent adhesion In addition, it relates to a pressure-sensitive adhesive layer capable of reusing the optical member because the adhesion is lowered under the conditions of -110° C. or less, that is, peeling from the optical member, that is, easy to remove, and an optical member and an image display device including the same.

Description

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

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

DESCRIPTION OF RELATED ART The field|area of portable electronic devices, such as a mobile phone and a portable information terminal device, WHEREIN: The adhesive is used for fixing between various members. As the adhesive, an optically clear resin (OCR), a liquid adhesive, and an optically clear adhesive (OCA), 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 that has recently been spotlighted.

In this regard, Korean Patent Application Laid-Open No. 10-2014-0019759 discloses a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer having an acrylic polymer containing 9 to 30% by mass of a structural unit derived from a polar monomer having excellent pressure adhesion and drop impact resistance. sheet is described.

However, in the case of the OCA-type pressure-sensitive adhesive having excellent adhesive strength as described above, it is difficult to remove and peel the pressure-sensitive adhesive layer as much as the adhesive strength is excellent, so that it is difficult to recover and rework the used optical member.

In this regard, Korean Patent Application Laid-Open No. 10-2016-0011785 discloses an acrylic photocurable resin formed by polymerization of a monomer component including two different types of (meth)acrylic ester monomers, and the two types of (meth)acrylic monomers. One of them is a tackifying monomer, and the tackifying monomer is an acrylate containing a C6-C20 alicyclic condensed ring or a fused ring. have.

However, in the case of the pressure-sensitive adhesive composition of the patent document, there is a problem that the base material to be used for the pressure-sensitive adhesive composition is limited to a polyimide substrate, and there is a problem that it is difficult to reuse the optical member because the removal of the pressure-sensitive adhesive composition is not sufficient.

Republic of Korea Patent Publication No. 10-2014-0019759 (2014.02.17) Republic of Korea Patent Publication No. 10-2016-0011785 (2016.02.02)

The present invention is to solve the above problems, and an object of the present invention is to provide a pressure-sensitive adhesive layer having excellent peelability at low temperature and easy to clean.

The pressure-sensitive adhesive layer of the present invention for achieving the above object is characterized in that the elastic modulus at 25 ° C. is 1.0 × 10 ⁵ to 1.5 × 10 ⁶ Pa, and the adhesive force is 0.15 MPa or less under the conditions of -110 °C or less.

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

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

The pressure-sensitive adhesive layer of the present invention has an advantage of being easy to clean because it has excellent peelability at low temperatures.

In addition, the optical member of the present invention has an advantage of excellent reworkability by including the above-described pressure-sensitive adhesive layer.

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

Figure 1 (a) is an image of a sample used in the low-temperature adhesive force measurement of the present invention.
Figure 1 (b) is an image of a jig for fixing the sample used in the low-temperature adhesion measurement of the present invention.
Figure 1 (c) is an image of measuring the low-temperature adhesion of the present invention.

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.

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

< adhesive layer >

According to one aspect of the present invention, the adhesive layer of the present invention has an elastic modulus at 25° C. of 1.0 × 10 ⁵ to 1.5 × 10 ⁶ Pa, and has an adhesive force of 0.15 MPa or less under the conditions of -110° C. or less. Not only can it be applied to an excellent and flexible optical member, but also the adhesion is lowered under the condition of -110° C. or less, so that peeling from the optical member, that is, it is easy to remove, there is an advantage that the optical member can be reworked.

In addition, according to an embodiment of the present invention, the method for measuring the adhesion includes the steps of: i) bonding two glass substrates using an adhesive layer; ii) preparing a sample by placing the bonded glass substrate under conditions of 50° C. and 7 atm for 30 minutes; iii) immersing the sample in liquid nitrogen for 7 to 9 seconds and then taking it out; and iv) measuring the adhesion of the sample treated with liquid nitrogen within 10 seconds and under the conditions of 20 mm/min; may include. In this case, the evaluation of the adhesion may be measured using a Universal Testing Machine (UTM) manufactured by INSTRON. Measuring the adhesion under such conditions takes into account that the pressure-sensitive adhesive layer can be cleaned under similar conditions.

adhesive composition

According to one embodiment of the present invention, the pressure-sensitive adhesive layer of the present invention may include an acrylate-based monomer (A), an acrylic polymer (B), and a photopolymerization initiator (C).

Acrylates Monomer (A)

The acrylate-based monomer (A) is a component that imparts durability to the pressure-sensitive adhesive composition and maintains storage modulus, and can facilitate coating by diluting the solvent-free pressure-sensitive adhesive composition to adjust the viscosity.

The kind of the said acrylate monomer (A) is not specifically limited, Usually, the 1-6 functional monomer which can be hardened|cured by photopolymerization is mentioned. Specifically, n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl ( meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, pentyl (meth) acrylate, n-octyl (meth) acrylic Rate, isooctyl (meth) acrylate, 2-methylbutyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, isoamyl (meth) acrylate, n-decyl (meth) ) acrylate, isodecyl (meth) acrylate, isobornyl (meth) acrylate, 4-methyl-2-pentyl (meth) acrylate, dodecyl (meth) acrylate, 2-dodecyl thioethyl (meth) Acrylate, lauryl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate , hydroxybutyl (meth) acrylate, allyl (meth) acrylate, stearyl (meth) acrylate, phenoxyethyl (meth) acrylate, tetrafurfuryl (meth) acrylate, tetrahydrofuryl (meth) acrylic monofunctional monomers such as late and acryloylmorpholine; 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propane Diol diacrylate, 1,9-nonanediol diacrylate, ethylene glycol di(meth)acrylate, bisphenol A-ethylene glycol diacrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate Acrylate, tetraethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylic rate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified di(meth)acrylate, bis(2-hydroxyethyl)isocyanurate di( Meth)acrylate, di(acryloxyethyl)isocyanurate, allylated cyclohexyldi(meth)acrylate, dimethyloldicyclopentane diacrylate, ethylene oxide-modified hexahydrophthalic acid diacrylate, tricyclodecanedimethanol bifunctional monomers such as acrylate, neopentyl glycol-modified trimethylolpropane diacrylate, and adamantane diacrylate; Trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid modified trimethylolpropane tri(meth)acrylate, propylene oxide modified trimethylolpropane tri trifunctional monomers such as (meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, and glycerol tri(meth)acrylate; tetrafunctional monomers such as diglycerin tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropanetetra(meth)acrylate, and tetramethylolpropanetetra(meth)acrylate; 5 functional monomers such as dipentaerythritol penta(meth)acrylate and propionic acid-modified dipentaerythritol penta(meth)acrylate; Hexafunctional monomers, such as dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate, etc. are mentioned. Among them, 2-ethylhexyl (meth) acrylate and isobornyl (meth) acrylate may be preferably used, and these may be used alone or in combination of two or more.

The content of the acrylate-based monomer (A) may be included in an amount of 15 to 70% by weight, specifically 30 to 70% by weight, more specifically 40 to 60% by weight, based on 100% by weight of the total pressure-sensitive adhesive composition including the same. may be included. When the content of the acrylate-based monomer (A) is included within the above range, the pressure-sensitive adhesive composition including the same can be sufficiently cured, and there is an advantage that can prevent problems such as curing shrinkage due to good coatability.

Acrylic polymer (B)

According to an embodiment of the present invention, the acrylic polymer (B) contains 50 to 100 parts by weight of an acrylic monomer (b1) containing a linear, branched or alicyclic alkyl group having 1 to 20 carbon atoms and 0 to 20 parts by weight of a polar monomer (b2) It may be copolymerized including parts by weight. At this time, when the content of the polar monomer is out of the above range, the adhesion at low temperature may increase, so that the cleaning property may be deteriorated.

The acrylic monomer (b1) specifically includes (meth) acrylic acid alkyl ester, more specifically (meth) methyl acrylate, (meth) ethyl acrylate, (meth) acrylic acid propyl, (meth) acrylic acid isopropyl, ( (meth) acrylate n-butyl, (meth) acrylate isobutyl, (meth) acrylate s-butyl, (meth) acrylate t-butyl, (meth) acrylate pentyl, (meth) acrylate isopentyl, (meth) acrylic acid hexyl, ( Heptyl acrylate, (meth) octyl acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylic acid, (meth) acrylic acid Isodecyl, (meth)acrylic acid undecyl, (meth)acrylic acid dodecyl, (meth)acrylic acid tridecyl, (meth)acrylic acid tetradecyl, (meth)acrylic acid pentadecyl, (meth)acrylic acid hexadecyl, (meth)acrylic acid hepta Decyl, (meth)acrylic acid octadecyl, (meth)acrylic acid nonadecyl, (meth)acrylic acid eicosyl, isodecyl methacrylate, etc. are mentioned. The said (meth)acrylic acid alkylester may be used individually or in combination of 2 or more types. In addition, in this specification, "(meth)acryl" shall represent "acryl" and/or "methacryl" (either one or both of "acryl" and "methacryl").

The polar monomer (b2) contains a monomer containing a polymerizable unsaturated bond together with at least one polar group, specifically (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, Carboxyl group-containing monomers, such as these acid anhydrides (For example, 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-butoxymethyl, (meth)acrylic acid 6-hydroxyhexyl; hydroxyl group (hydroxyl group)-containing monomers such as vinyl alcohol, allyl alcohol, and hydroxycyclohexylphenyl ketone; (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; Isocyanate group-containing monomers, such as 2-methacryloyloxyethyl isocyanate, etc. are mentioned, However, It is not limited to this.

According to one embodiment of the present invention, the weight average molecular weight of the acrylic polymer (B) is preferably 1 million or less in that it is easy to control the viscosity required for coating the pressure-sensitive adhesive composition comprising the same, and the acrylate-based monomer ( The content ratio of A) and the acrylic polymer (B) is preferably 1:1 to 5:1.

light curing initiator (C)

The photopolymerization initiator (C) may be used without any particular limitation as long as it is used as a photopolymerization initiator in the industry, and is not particularly limited in the present invention, but specifically, a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, α-ke Tall photoinitiator, aromatic sulfonyl chloride photoinitiator, photoactive oxime photoinitiator, benzoin photoinitiator, benzyl photoinitiator, benzophenone photoinitiator, ketal photoinitiator, thioxanthone photoinitiator, acylphosphine oxide A system 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, anisolemethyl ether, and the like, but are not limited thereto.

Examples of the acetophenone-based photopolymerization initiator include 1-hydroxycyclohexylphenylketone, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, and 1-[4-(2-hydroxyethoxy). )-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, methoxy acetophenone, 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 are 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-dichloro thioxanthone, 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's not going to be

According to one embodiment of the present invention, the content of the photopolymerization initiator (C) may be included in an amount of 0.01 to 3 parts by weight based on 100 parts by weight of the total of the acrylic polymer (B) included therewith. When the content of the photopolymerization initiator (C) 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 (D)

According to one embodiment of the present invention, the pressure-sensitive adhesive composition may further include an additive (D).

The additive (D) 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.), UV absorbers, antioxidants, chain transfer agents, plasticizers, softeners, antistatic agents, solvents, and the like may be mentioned, but are not limited thereto, and these may be used alone or in combination of two or more.

In addition, in the pressure-sensitive adhesive layer of the present invention, within the range that can achieve the object of the present invention, for example, acrylic pressure-sensitive adhesive, rubber-based pressure-sensitive adhesive, vinyl alkyl ether-based pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, polyester-based pressure-sensitive adhesive, polyamide-based pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive Other pressure-sensitive adhesives such as pressure-sensitive adhesives, fluorinated pressure-sensitive adhesives, and epoxy-based pressure-sensitive adhesives may be contained, and these may be used alone or in combination of two or more.

According to one aspect of the present invention, the adhesive layer of the present invention has an elastic modulus at 25° C. of 1.0 × 10 ⁵ to 1.5 × 10 ⁶ Pa, and has an adhesive force of 0.15 MPa or less under the conditions of -110° C. or less. Not only can it be applied to an excellent and flexible optical member, but also the adhesion is lowered under the condition of -110° C. or less, so that peeling from the optical member, ie, removal, is easy, so that the optical member can be reused.

< optical member >

Another aspect of the present invention is an optical member including the pressure-sensitive adhesive layer described above.

The optical member may be a flexible optical member by including the pressure-sensitive adhesive layer of the present invention, and has the advantage that the pressure-sensitive adhesive layer can be easily removed and reused.

Specifically, the optical member may include, but is not limited to, a window glass, a window film, a polarizing plate, a retardation plate, an optical film for a plasma display, a conductive film for a touch panel, a reflective sheet, a luminance enhancing film, etc. Other optical members are also applicable.

<Image display device>

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

The image display device is not particularly limited, but for example, a liquid crystal display device (LCD), a field emission display device (FED), a plasma display device (PDP), an organic light emitting device (OLED), a flexible display device, etc. can be heard

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 is 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.

In a 1L reactor in which nitrogen gas is refluxed and a cooling device is installed for easy temperature control, 50% by weight of 2-ethylhexylacrylate (2-EHA) monomer, 40% by weight of methyl methacrylate (MMA) monomer, and 5-hydro After adding a monomer mixture composed of 10% by weight of oxypropyl acrylate (5-HPA) monomer, nitrogen gas was purged for 1 hour to remove oxygen, and then 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 an acrylic syrup having a polymer conversion rate of 25%.

production example 2 to 5.

It was prepared in the same manner as in Preparation Example 1, but (meth)acrylate syrup was prepared with the composition shown in Table 1 below, and the polymer conversion rate of each Preparation Example is also shown in Table 1 below.

Experimental example 1. Evaluation of weight average molecular weight and molecular weight distribution

The weight average molecular weight and molecular weight distribution of the (meth)acrylate syrup prepared in Preparation Example was measured using GPC under the following conditions. The measurement result was converted using standard polystyrene of Agilent system for preparation of a calibration curve. The results are shown in Table 1 below.

<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 (wt%) Photoinitiator (parts by weight) Polymer conversion (%) Weight average molecular weight (unit: ten thousand) 2-EHA IDMA MMA NBMA 5-HPA DMAA Preparation Example 1 (A1) 50 - 40 - 10 - 0.5 25 70 Preparation Example 2 (A2) - 45 45 - - - 0.5 27 65 Production Example 3 (A3) 45 - 40 15 - - 0.5 26 60 Production Example 4 (A4) 40 - 35 - 25 - 0.5 27 71 Production Example 5 (A5) 24 - 25 - 31 20 0.5 25 69 2-EHA: 2-ethylhexyl acrylate
IDMA: isodecyl methacrylate
MMA: methyl methacrylate
NBMA: N-butoxymethylacrylamide
5-HPA: 5-hydroxypentyl acrylate
DMAA: Dimethylacrylamide
Photoinitiator: 1-hydroxy cyclohexylphenyl ketone

Example 1 to 3 and comparative example 1 to 2

A pressure-sensitive adhesive composition was prepared by mixing the content of the (meth)acrylate syrup and photoinitiator of 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, cm ² , based on UVV) to prepare a sheet.

Experimental example 2. Elastic Modulus Measurement

The storage modulus of the adhesive sheets prepared in Examples and Comparative Examples at 25° C. was measured using a viscoelasticity measuring device (MCR-301, manufactured by Anton Paar). More specifically, set the size of the adhesive layer sample to 30mm in length × 30mm in width, and after bonding the measurement sample to the glass substrate and adhering to the measuring tip, the frequency is 1.0Hz, 　transformation in a temperature range of -30 to 100°C. It was measured under the conditions of 2%, 　 temperature increase rate 　 5/min, and obtained by reading the measured value at 25°C, and the measurement results are shown in Table 2 below.

Experimental example 3. Low temperature adhesion measurement

The low-temperature adhesion of the adhesive sheets prepared in Examples and Comparative Examples was measured using INSTRON's UTM equipment. 1, the size of the pressure-sensitive adhesive sheet prepared in Examples and Comparative Examples is cut to 10 mm × 10 mm on a 23 mm × 60 mm glass plate, and then the release film on one side is removed and bonded to the center of the glass plate. (see Fig. 1a). After removing the remaining release film of the bonded adhesive, a 23mm × 60mm glass plate is attached in a cross (+) shape (see FIG. 1 a). Treated in an autoclave at 50° C., 7 atm for 30 minutes. After immersing the prepared sample in liquid nitrogen for 8 seconds, immediately put it on a jig (refer to b of FIG. 1) after taking it out (within 7 seconds) and press it in the vertical direction of the adhesive surface at a speed of 20 mm/min to measure low-temperature adhesion (FIG. 1) see c). The measurement results are shown in Table 2 below.

Example comparative example One 2 3 One 2 (meth)acrylate syrup (parts by weight) type A1 A2 A3 A4 A5 content 100 100 100 100 100 photoinitiator ¹⁾
(parts by weight) 0.5 0.5 0.5 0.5 0.5 Storage modulus (Pa, 1Hz) 0.5×10 ⁶ 1.0×10 ⁶ 1.5×10 ⁶ 0.09×10 ⁶ 1.9×10 ⁶ Low temperature adhesion (MPa) 0.1 0.08 0.13 0.17 0.32 1)2,2-dimethoxy-1,2-diphenylethanone

Experimental Example 4: Detergency evaluation

delete

After attaching the adhesive sheets prepared in Examples 1 to 3 and Comparative Examples 1 to 2 to the cover glass, immersing them in liquid nitrogen for 10 seconds to peel them again, and then using a microfiber wiper (KM) soaked in ethanol with the remaining adhesive in the cover glass. It was washed for 5 minutes and evaluated according to the following evaluation criteria, and the results are shown in Table 3 below.

<Evaluation criteria>

○: 100% washed

△: less than 100% 80% or more washed

×: less than 80% cleaned

Experimental example 5: Durability (heat resistance, moisture heat resistance ) evaluation

The pressure-sensitive adhesive sheet prepared by peeling the release film on one side of the pressure-sensitive adhesive sheet prepared in Examples 1 to 3 and or Comparative Examples 1 to 2, corona-treating the 40 μm cycloolefin (COP) film and the pressure-sensitive adhesive surface, and bonding the pressure-sensitive adhesive sheet to 90 mm After cutting to a size of × 170 mm, peeling the release film attached to the other side, and attaching it 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 for 500 hours at a temperature of 100 ℃, and the moisture heat resistance property was left for 500 hours under the conditions of 85 ℃ temperature and 85% RH, and the occurrence of bubbles or partial peeling was observed. The evaluation criteria are as follows, and both heat resistance and heat resistance are as follows, and the results are shown in Table 3 below.

<Evaluation criteria>

ⓞ: No air bubbles or partial peeling

○: Less than 5 bubbles or partial peeling

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

×: 10 or more bubbles or partial peeling

Example comparative example One 2 3 One 2 detergency ○ ○ ○ × × heat-and-moisture resistance ○ ○ ⓞ △ × heat resistance ○ ○ ○ ○ △

Referring to Table 3, in the case of Examples 1 to 3, which satisfy the elastic modulus and low-temperature adhesive strength of the present invention, the cleaning property is higher than that of Comparative Examples 1 and 2, which does not satisfy any one of the elastic modulus and low-temperature adhesive strength of the present invention. It was confirmed that not only this was excellent, but also durability such as heat resistance and heat-and-moisture resistance was excellent.

Claims (9)

An elastic modulus at 25°C is 1.0 × 10 ⁵ to 1.5 × 10 ⁶ Pa, and the adhesive layer has an adhesive force of 0.15 MPa or less under the conditions of -110°C or less,
The pressure-sensitive adhesive layer includes a cured product of a pressure-sensitive adhesive composition comprising a monofunctional acrylate-based monomer (A), an acrylic polymer (B) and a photopolymerization initiator (C),
The content ratio of the monofunctional acrylate-based monomer (A) and the acrylic polymer (B) is 1:1 to 5:1,
The monofunctional acrylate-based monomer (A) is included in an amount of 30 to 70% by weight based on the total weight of the pressure-sensitive adhesive composition,
The acrylic polymer is copolymerized with 50 to 100 parts by weight of an acrylic monomer (b1) containing a linear, branched or alicyclic alkyl group having 1 to 20 carbon atoms and 0 to 20 parts by weight of a polar monomer (b2),
The method of measuring the adhesion is
i) bonding two glass substrates using an adhesive layer;
ii) preparing a sample by placing the bonded glass substrate at a condition of 50° C. 7 atm for 30 minutes;
iii) immersing the sample in liquid nitrogen for 7 to 9 seconds and then taking it out; and
iv) measuring the sample treated with liquid nitrogen within 7 seconds at a condition of 20 mm/min; characterized in that it comprises a,
adhesive layer. delete delete delete According to claim 1,
The content of the photopolymerization initiator (C) is based on the total 100 parts by weight of the acrylic polymer (B), 0.01 to 3 parts by weight of the pressure-sensitive adhesive layer. According to claim 1,
The weight average molecular weight of the acrylic polymer (B) is a pressure-sensitive adhesive layer, characterized in that not more than 1 million. According to claim 1,
The pressure-sensitive adhesive composition further comprises an additive (D). An optical member comprising the pressure-sensitive adhesive layer of any one of claims 1, 5 to 7. An image display device comprising the optical member of claim 8.

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