KR101983743B1 - Adhesive layer, optical member and display device using the same - Google Patents

Abstract

The present invention is characterized in that the modulus of elasticity at 25 ° C is 1.0 × 10 ⁵ to 1.5 × 10 ⁶ Pa, and the reaction rate calculated by the following formula (1) is 95 to 98%, whereby the adhesive force is excellent and is also applied to a flexible optical member To an optical member and an image display device which are capable of reusing an optical member by facilitating separation or removal from the optical member during cleaning for reuse of the optical member.
[Equation 1]
Reaction rate = {(ZX) / (YX)} 100
(In the above formula (1)
X is the weight of the glass substrate,
Y is the total weight of the pressure-sensitive adhesive layer bonded on one surface of the glass substrate,
Z is the weight of the glass substrate to which the pressure-sensitive adhesive layer is adhered after drying for 1 hour under vacuum drying at 130 DEG C and then left in a desiccator for 30 minutes.

Description

TECHNICAL FIELD [0001] The present invention relates to an adhesive layer, an optical member including the adhesive layer, and an image display device.

The present invention relates to a pressure-sensitive adhesive layer, an optical member including the pressure-sensitive adhesive layer, and an image display device.

BACKGROUND ART [0002] In the field of portable electronic devices such as cellular phones and portable information terminals, an adhesive is used for fixing between various members. As the pressure sensitive adhesive, an optically clear resin (OCR), which is a liquid type pressure sensitive adhesive, and an OCA (optically clear adhesive), which is a sheet type pressure sensitive adhesive, are used.

Particularly, the OCR type pressure-sensitive adhesive has been used for manufacturing various electronic devices because it is easy to remove by using ethanol or the like and thus it is easy to recover optical members used in defective products that may occur in the manufacture of electronic devices. In the case of the pressure-sensitive adhesive, there is a problem that the adhesive force is insufficient to be applied to a flexible image display device which has recently been spotlighted. In recent years, the use of an OCA-type pressure-sensitive adhesive excellent in adhesive strength is increasing.

In this connection, Korean Patent Laid-Open Publication No. 10-2014-0019759 discloses a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer and a pressure-sensitive adhesive layer having an acryl-based polymer containing 9 to 30 mass% of constitutional units derived from a polar monomer, Sheet is described.

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

In this connection, Korean Patent Laid-Open No. 10-2016-0011785 discloses an acrylic photocurable resin formed by polymerizing monomer components containing two different (meth) acrylic ester monomers, wherein the two (meth) acrylic monomers Is a tackiness-imparting monomer, and the tackifier-imparting monomer is a C6-C20 alicyclic condensed ring or an acrylate containing a fused ring, the pressure-sensitive adhesive composition is excellent in adhesion to a polyimide base and peel strength have.

However, in the case of the pressure-sensitive adhesive composition of the patent document, there is a problem that the substrate to be used for the pressure-sensitive adhesive composition is limited to the polyimide substrate, and the removal of the pressure-sensitive adhesive composition is insufficient.

Korean Patent Publication No. 10-2014-0019759 (Feb. Korean Patent Publication No. 10-2016-0011785 (2016.02.02)

An object of the present invention is to provide a pressure-sensitive adhesive layer which not only has excellent adhesive strength, but also has excellent cleaning power upon cleaning, and is easy to clean.

In order to achieve the above object, the pressure-sensitive adhesive layer of the present invention is characterized in that the modulus of elasticity at 25 ° C is 1.0 × 10 ⁵ to 1.5 × 10 ⁶ Pa, and the reaction rate calculated by the following formula 1 is 95 to 98%.

[Equation 1]

Reaction rate = {(Z-X) / (Y-X)} 100

(In the above formula (1)

X is the weight of the glass substrate,

Y is the total weight of the pressure-sensitive adhesive layer bonded on one surface of the glass substrate,

And Z is the weight of the glass substrate to which the pressure-sensitive adhesive layer is adhered after drying for 1 hour under vacuum drying at 130 캜 and then left in a desiccator for 30 minutes).

Further, the optical member of the present invention is characterized by including the pressure-sensitive adhesive layer.

Further, the image display apparatus of the present invention is characterized by including the optical member.

 The pressure-sensitive adhesive layer of the present invention not only has excellent adhesive force but also has an excellent reaction rate and is easy to clean.

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

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

Whenever a part is referred to as " including " an element in the present invention, it is to be understood that it may include other elements as well, without departing from the other elements unless specifically stated otherwise.

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

< The pressure- >

According to one embodiment of the present invention, the pressure-sensitive adhesive layer of the present invention is characterized in that the modulus of elasticity at 25 ° C is 1.0 × 10 ⁵ to 1.5 × 10 ⁶ Pa, and the reaction rate calculated by the following formula 1 is 95 to 98% , It is possible to apply the present invention to a flexible optical member because of its excellent adhesive force, and also it is easy to peel off or remove the optical member from the optical member during cleaning for reuse of the optical member, which is advantageous in that the optical member can be reworked have.

[Equation 1]

Reaction rate = {(Z-X) / (Y-X)} 100

(In the above formula (1)

X is the weight of the glass substrate,

Y is the total weight of the pressure-sensitive adhesive layer bonded on one surface of the glass substrate,

Z is the weight when the glass substrate to which the pressure-sensitive adhesive layer is bonded is dried in a vacuum drying at 130 ° C (pressure: 6 × 10 ^-2 Pa or more) for 1 hour and then left in a desiccator for 30 minutes.

Pressure-sensitive 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).

Acrylate series  The monomer (A)

The acrylate-based monomer (A) is a component capable of imparting durability to the pressure-sensitive adhesive composition and maintaining the storage elastic modulus, and capable of facilitating coating by diluting the solvent-free pressure-sensitive adhesive composition and controlling viscosity thereof.

The kind of the acrylate monomer (A) is not particularly limited, and examples thereof include 1 to 6 functional monomers which can be cured by photopolymerization. Specific examples thereof include n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, (Meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (Meth) acrylate, isooctyl (meth) acrylate, 2-methylbutyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (Meth) acrylate, dodecyl (meth) acrylate, isodecyl (meth) acrylate, isobodyl (meth) acrylate, Acrylate, lauryl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2- Acrylates such as ethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, allyl Monofunctional monomers such as ethyl (meth) acrylate, tetrapurfuryl (meth) acrylate, tetrahydrofuryl (meth) acrylate and acryloylmorpholine; Butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, Ethylene glycol di (meth) acrylate, bisphenol A-ethylene glycol diacrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, (Meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di Acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) acrylate, bis (2-hydroxyethyl) isocyanurate di Methacrylate , Di (acryloxyethyl) isocyanurate, allyl cyclohexyl di (meth) acrylate, dimethylol dicyclopentane diacrylate, ethylene oxide modified hexahydrophthalic acid diacrylate, tricyclodecane dimethanol acrylate, neo Bifunctional monomers such as pentyl glycol-modified trimethylol propane diacrylate and adamantanedicarylate; (Meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified trimethylol propane tri Trifunctional monomers such as (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, tris (acryloxyethyl) isocyanurate and glycerol tri (meth) acrylate; Quaternary functional monomers such as diglycerin tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylol propane tetra (meth) acrylate and tetramethylol propane tetra (meth) acrylate; Pentafunctional monomers such as dipentaerythritol penta (meth) acrylate and propionic acid-modified dipentaerythritol penta (meth) acrylate; And hexafunctional monomers such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. Of these, 2-ethylhexyl (meth) acrylate and isobonyl (meth) acrylate are preferably used, and they may be used alone or in combination of two or more.

According to an embodiment of the present invention, the acrylate-based monomer (A) may be contained in an amount of 15 to 70% by weight, more preferably 30 to 70% by weight, More specifically from 40 to 60% by weight. When the content of the acrylate-based monomer (A) is within the above range, the pressure-sensitive adhesive composition containing the acrylate-based monomer (A) can be sufficiently cured and there is an advantage in that the problem of hardening shrinkage and the like can be prevented.

The acrylic polymer (B)

According to one embodiment of the present invention, the acrylic polymer (B) comprises 50 to 100 parts by weight of an acrylic monomer (b1) having a straight chain, branched or alicyclic alkyl group having 1 to 20 carbon atoms and the polar monomer (b2) By weight based on the total weight of the composition. At this time, when the content of the polar monomer is out of the above range, the heat and humidity resistance may be deteriorated.

Specific examples of the acrylic monomer (b1) include alkyl (meth) acrylates, and more specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (Meth) acrylate, isobutyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t- (Meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (Meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, isodecyl Decyl, (meth) arcs Acid octadecyl, (meth) acrylate, nonadecyl (meth) acrylate, eicosyl. The (meth) acrylic acid alkyl esters may be used alone or in combination of two or more. In the present specification, the term "(meth) acrylic" means "acrylic" and / or "methacrylic" (either or both of "acrylic" and "methacrylic").

The polar monomer (b2) comprises a monomer containing a polymerizable unsaturated bond together with at least one polar group, and specifically includes at least one of (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, Carboxyl group-containing monomers such as acid anhydrides thereof (for example, acid anhydride-containing monomers such as maleic anhydride and itaconic anhydride); (Meth) acrylate such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl Containing monomer); (Meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl - 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 glycidyl (meth) acrylate and methylglycidyl (meth) acrylate; Cyano group-containing monomers such as acrylonitrile and methacrylonitrile; Containing vinyl monomers such as N-vinyl-2-pyrrolidone, (meth) acryloylmorpholine, N-vinylpiperidone, N-vinylpiperazine, N-vinylpyrrole, N- ; 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 cyclohexylmaleimide and isopropylmaleimide; And isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate, but are not limited thereto.

According to one embodiment of the present invention, the weight average molecular weight of the acrylic polymer (B) is preferably not more than 1,000,000 because it is easy to control the viscosity required for coating the pressure sensitive adhesive composition containing the acrylic polymer (B) A) and the acrylic polymer (B) is preferably 1: 1 to 5: 1.

Light curing Initiator (C)

The photopolymerization initiator (C) can be used without any particular limitation as long as it is used as a photopolymerization initiator in the art, and is not specifically limited in the present invention. Specifically, a benzoin ether photopolymerization initiator, an acetophenone photopolymerization initiator, Based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketene-based photopolymerization initiator, a thioxanthone photopolymerization initiator, an acylphosphine oxide Based photopolymerization initiator and the like.

Examples of the benzoin ether 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, anisole methyl ether, and the like, but are not limited thereto.

Examples of the acetophenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1- [4- (2-hydroxyethoxy 2-hydroxy-2-methyl-1-phenyl-propan-1-one, methoxyacetophenone, and the like . Examples of the? -Ketol-based photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy- 1-on, and the like. However, the present invention is not limited thereto.

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

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

Examples of the benzoin-based photopolymerization initiator include benzoin. Examples of the benzyl-based photopolymerization initiator include benzyl. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoyl Benzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and? -Hydroxycyclohexyl phenyl ketone, but are not limited thereto.

Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal and the like, and the thioxanthene photopolymerization initiator includes, for example, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2 , 4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, Dodecylthioxanthone, and the like, but are not limited thereto.

Examples of the acylphosphine photopolymerization initiator include bis (2,6-dimethoxybenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) Bis (2,6-dimethoxybenzoyl) -n-butylphosphine oxide, bis (2,6-dimethoxybenzoyl) - (2-methylpropan- (2,6-dimethoxybenzoyl) -t-butylphosphine oxide, bis (2,6-dimethoxybenzoyl) cyclohexylphosphine oxide, (2-methoxybenzoyl) octylphosphine oxide, bis (2-methoxybenzoyl) (2-methylpropan-1-yl) (2,6-diethoxybenzoyl) (1-methylpropane-1-yl) phosphine oxide, bis -1-yl) phosphine oxide, bis (2,6-dibutoxybenzoyl) (2-methylpropan-1-yl) (2,4-dimethoxybenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) Bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis Bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6- dimethoxybenzoyl) Phenylethylphosphine oxide, 2,6-dimethoxybenzoylbenzylbutylphosphine oxide, 2,6-dimethoxybenzoylbenzyloctylphosphine oxide, bis (2,4,6-trimethylbenzoyl) (2,4,6-trimethylbenzoyl) -2-methylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -4-methylphenylphosphine oxide, bis 6-trimethylbenzoyl) -2,5-diethylphenylphosphine oxide, bis ( 2,4,6-trimethylbenzoyl) -2,3,5,6-tetramethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-di-n-butoxyphenylphosphine oxide , 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) iso Butylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) Bis (2,4,6-trimethylbenzoyl) phosphineoxide] decane, tri (2-methylbenzoyl) phosphine oxide, Seeds, and the like, but the present invention is not limited thereto.

The content of the photopolymerization initiator (C) may be 0.01 to 3 parts by weight based on 100 parts by weight of the acrylic polymer (B). When the content of the photopolymerization initiator (C) is within the above range, the polymerization reaction can be sufficiently carried out, the lowering of the molecular weight of the resulting polymer can be suppressed, and the cohesive force of the formed pressure-sensitive adhesive layer can be secured.

Additive (D)

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

The additive (D) can be used without any particular limitation according to the purpose of the user within the scope of achieving the object of the present invention. Specifically, the additive (D) can be used as a crosslinking accelerator, a silane coupling agent, an antioxidant, Ultraviolet absorbers, antioxidants, chain transfer agents, plasticizers, softening agents, antistatic agents, solvents and the like. However, the present invention is not limited thereto, and they may be used alone or in combination of two or more.

The pressure sensitive adhesive layer of the present invention may contain, for example, an acrylic pressure sensitive adhesive, a rubber pressure sensitive adhesive, a vinyl alkyl ether pressure sensitive adhesive, a silicone pressure sensitive adhesive, a polyester pressure sensitive adhesive, a polyamide pressure sensitive adhesive, Other pressure-sensitive adhesives such as pressure-sensitive adhesives, fluorine pressure-sensitive adhesives, and epoxy-based pressure-sensitive adhesives may be contained, and they may be used alone or in combination of two or more.

According to one embodiment of the present invention, the pressure-sensitive adhesive layer of the present invention is characterized in that the modulus of elasticity at 25 ° C is 1.0 × 10 ⁵ to 1.5 × 10 ⁶ Pa, and the reaction rate calculated by the above-mentioned formula (1) is 95 to 98% The present invention is not only applicable to a flexible optical member having an excellent adhesive force but also has an advantage that the optical member can be reused because it is easy to peel off or remove from the optical member during cleaning for reuse of the optical member.

< Optical member >

Another aspect of the present invention is an optical member comprising the aforementioned pressure-sensitive adhesive layer.

By including the pressure sensitive adhesive layer of the present invention, the optical member has an advantage that the pressure sensitive adhesive layer can be easily removed and reused.

Examples of the optical member include 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 enhancement film, but the present invention is not limited thereto. Do.

<Image Display Device>

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

The image display apparatus is not particularly limited, but may be a liquid crystal display (LCD), a field emission display (FED), a plasma display (PDP), an organic electroluminescence (OLED) .

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. , And 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 " representing the contents are by weight unless otherwise specified.

Manufacturing example : ( Meta ) Acrylate  Manufacture of syrups

Manufacturing example  One.

50% by weight of 2-ethylhexyl acrylate (2-EHA) monomer, 40% by weight of isobornyl acrylate (IBOA) monomer, 2-ethylhexyl acrylate And 10% by weight of a hydroxypropyl acrylate (2-HPA) monomer, and then nitrogen gas was purged for 1 hour in order to remove oxygen, and then kept at 80 ° C. When the monomer mixture was uniformly mixed, the total weight of the monomer mixture was adjusted to 100 parts by weight, and 0.5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone was added as a photoinitiator. Then, the mixture was stirred and irradiated with a UV lamp (10 mW) to prepare an acrylic syrup having a polymer conversion of 25%.

Manufacturing example  2 to 5.

(Meth) acrylate syrup was prepared in the same manner as in Preparation Example 1 and the composition shown in the following Table 1, and the polymer conversion ratios of the respective preparation examples are 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 the above Preparation Example were measured using GPC under the following conditions. For the preparation of the calibration curve, the measurement results were converted using standard polystyrene of the Agilent system. The results are shown in Table 1 below.

<Conditions for measuring weight average molecular weight>

Meter: Agilent GPC (Agilent 1200 series, USA)

Column: Two PL Mixed B connections

Column temperature: 40 ° C

Eluent: tetrahydrofuran

Flow rate: 1.0 mL / min

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

division (Meth) acrylate monomer (% by weight) Photoinitiator
(Parts by weight) Polymer
Conversion Rate
(%) Weight average
Molecular Weight
(Unit: million) EHA DA IBOA DMAA 2-HPA Production Example 1 (A1) 50 - 40 - 10 0.5 25 70 Production Example 2 (A2) - 45 45 - 0 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) 30 - 30 - 40 0.5 28 58 EHA: Ethylhexyl acrylate
DA: Dodecyl acrylate
IBOA: isobornyl acrylate
DMAA: Dimethylacrylamide
2-HPA: 2-hydroxypropyl acrylate
Photoinitiator: 1-Hydroxy-cyclohexyl-phenyl-ketone

Example  1 to 4 and Comparative Example  1 to 3

The content of the (meth) acrylate syrup and the photoinitiator of the above Preparation Example was mixed in the composition shown in Table 2 to prepare a pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition prepared above was coated on a releasing film coated with a silicone release agent to a thickness of 150 占 퐉 and a release film was bonded thereon to produce a pressure-sensitive adhesive sheet. UV irradiation conditions were adjusted as shown in Table 1 The sheet was completed.

The prepared sheet was cut into a size of 4 cm x 5 cm, and one separator film was peeled off from a 5 cm x 7 cm glass. After joining to the glass, the remaining separator film was peeled off, and Z was confirmed.

[Equation 1]

Reaction rate = {(Z-X) / (Y-X)} 100

(In the above formula (1)

X is the weight of the glass substrate,

Y is the total weight of the pressure-sensitive adhesive layer bonded on one surface of the glass substrate,

Z is the pressure-sensitive adhesive layer is bonded to the glass substrate 130 ℃ vacuum drying: ^- the weight at the time was dried for 1 hour under (pressure more than 6X10 ² Pa), hayeoteul allowed to stand for 30 minutes in a desiccator).

Experimental Example  2. Modulus of elasticity measurement

The storage elastic moduli of each of the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples at 25 캜 were measured using a viscoelasticity measuring device (MCR-301, Anton Paar). More specifically, the adhesive layer sample size was 30 mm in length and 30 mm in width. After bonding the measurement sample to the glass substrate, the adhesive was adhered to the measurement tip, and at a temperature of -30 to 100 캜, 2% and a rate of temperature increase of 5 ° C / min, and reading the measured value at 25 ° C. The measurement results are shown in Table 2 below.

Example Comparative Example One 2 3 4 One 2 3 (Meth) acrylate syrup (parts by weight) Kinds A1 A2 A3 A4 A1 A1 A5 content 100 100 100 100 100 100 100 Photoinitiator
(Parts by weight) ¹⁾ 0.5 0.5 0.5 0.5 0.5 0.5 0.5 UV dose (mJ / cm ² ) 500 400 400 300 200 700 400 UV dose (mW / cm ² ) 1.8 1.5 1.5 1.5 1.8 1.8 1.5 Response rate 97.2 96.9 96.5 95.3 93.2 99.5 96.7 Storage modulus
(Pa, 1 Hz) 25 ℃ 1.3 × 10 ⁶ 1.4 × 10 ⁶ 1.5 × 10 ⁶ 1.5 × 10 ⁶ 5.0 × 10 ⁵ 1.3 × 10 ⁶ 8.5 × 10 ⁵ 1) 2,2-dimethoxy-1,2-diphenylethanone

Experimental Example  3: Cleanliness  evaluation

The adhesive sheets prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were attached to a cover glass, a smartphone panel was attached to the opposite side of the adhesive sheet to which the cover glass was attached, and immersed in liquid nitrogen for 10 seconds After peeling off, the remaining adhesive in the cover glass was washed with an ethanol-impregnated nonwoven fabric for 5 minutes, and the results were evaluated in accordance with the following evaluation criteria.

<Evaluation Criteria>

○: 100% cleaned

?: Less than 100% Less than 80%

×: Less than 80% cleaned

Experimental Example  4: Durability (heat resistance, Wet heat ) evaluation

A release sheet on one side of the pressure-sensitive adhesive sheet prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was peeled off, and a pressure-sensitive adhesive sheet prepared by corona-treating and bonding a cycloolefin (COP) And the release film attached to the other surface was peeled off and attached to a glass substrate (110 mm x 190 mm x 0.7 mm) to prepare a specimen. At this time, the applied pressure was 5 kg / cm &lt; 2 &gt;, and the clean room operation was performed so that bubbles or foreign matter would not occur.

The heat resistance characteristics were observed at 100 ° C. for 500 hours, and then the occurrence of bubbles or peeling was observed. The moisture resistance characteristics were observed at 85 ° C. and 85% RH for 500 hours, Respectively. The evaluation criteria are as follows, and the results are shown in Table 3 below.

<Evaluation Criteria>

Ⓞ: No bubble or partial peeling

○: Less than 5 bubbles or partial peeling

?: Bubbles or partial peeling 5 or more, less than 10

X: 10 or more bubbles or partial peeling

Example Comparative Example One 2 3 4 One 2 3 Cleanliness ○ ○ ○ ○ ○ × △ Humidity Durability ○ ○ Ⓞ ○ × ○ × Heat resistance ○ ○ Ⓞ ○ × ○ ×

With reference to Table 3, in Examples 1 to 4 satisfying the elastic modulus and the reaction rate of the present invention, it was found that the cleaning properties were superior to those of Comparative Examples 1 to 3 in which neither the elastic modulus nor the reaction rate of the present invention was satisfied But also excellent durability such as heat resistance and resistance to humid heat.

Claims (8)

And a modulus of elasticity at 25 캜 of from 1.0 10 ⁵ to 1.5 10 ⁶ Pa and a reaction rate calculated from the following equation (1): 95 to 98%;
[Equation 1]
Reaction rate = {(ZX) / (YX)} 100
(In the above formula (1)
X is the weight of the glass substrate,
Y is the total weight of the pressure-sensitive adhesive layer bonded on one surface of the glass substrate,
Z is the weight of the glass substrate on which the pressure-sensitive adhesive layer is bonded, after drying for 1 hour under vacuum drying at 130 DEG C and then leaving it in a desiccator for 30 minutes)
A cured product of a pressure-sensitive adhesive composition comprising an acrylate-based monomer (A), an acrylic polymer (B) and a photopolymerization initiator (C);
Wherein the acrylic polymer (B) has a weight average molecular weight of 100,000 to 1,000,000. The method according to claim 1,
The acrylic polymer (B) is copolymerized with 50 to 100 parts by weight of an acrylic monomer (b1) having a straight chain, branched or alicyclic alkyl group having 1 to 20 carbon atoms and 0 to 30 parts by weight of a polar monomer (b2) A pressure sensitive adhesive layer characterized by: 3. The method of claim 2,
Wherein the content ratio of the acrylate monomer (A) to the acrylic polymer (B) is 1: 1 to 5: 1. 3. The method of claim 2,
Wherein the content of the photopolymerization initiator (C) is 0.01 to 3 parts by weight based on 100 parts by weight of the total of the acrylic polymer (B). delete 3. The method of claim 2,
Wherein the pressure-sensitive adhesive composition further comprises an additive (D). An optical member comprising the pressure-sensitive adhesive layer according to any one of claims 1 to 4 and 6. An image display device comprising the optical member of claim 7.