KR101908290B1 - Double-sided pressure-sensitive adhesive sheet And Display device comprising the same - Google Patents

Abstract

The present invention relates to a double-sided pressure-sensitive adhesive sheet and an image display apparatus having the same, and more particularly to a double-sided pressure-sensitive adhesive sheet comprising a transparent structure having a first transparent substrate, a second transparent substrate and a transparent adhesive layer interposed between the transparent substrates, Wherein the transparent adhesive layer has a peel force of 0.1 to 5 N / 25 mm at a peeling speed of 300 mm / min, and is excellent in reworkability, so that the double-sided adhesive sheet can be repetitively peeled off and reattached, and an image display apparatus having the same will be.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided pressure-sensitive adhesive sheet,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a double-sided pressure-sensitive adhesive sheet and an image display apparatus having the same. More particularly, the present invention relates to a double-sided pressure-

2. Description of the Related Art A flat panel display device that has been widely used in place of a conventional CRT display device includes a liquid crystal display (LCD), a plasma display panel (PDP), an organic electro luminescence display (OLED) Etc., and related technologies are developing more and more. Also, the display device may have an input function such as a touch panel or the like at the same time.

In manufacturing these display devices and input devices, a transparent pressure sensitive adhesive sheet is used in various steps for attaching optical members, for example, between a backlight unit and a liquid crystal panel, or between a display module and a protective glass.

There are two representative embodiments of the adhesive mechanism of such a transparent pressure-sensitive adhesive sheet. One of them is a method of imparting releasability by softening the adhesive layer by applying heat as disclosed in Korean Patent Publication No. 2009-0077038. Another method is to use a crosslinked resin (bridged bridged bridged bridged bridged bridged bridged bridged bridged bridged bridged bridged bridged bridged bridged bridged bridges).

However, the above conventional techniques have a disadvantage in that it is difficult to ensure optical transparency, and that the factor causing peeling is poor in durability as a condition factor that can be involved in daily life or harsh conditions such as heat or ultraviolet rays. Accordingly, it is not suitable when the adhesion between the members occurs during the manufacturing process of the optical product and reattachment occurs after desorption.

However, it is necessary to develop a double-sided pressure-sensitive adhesive sheet having excellent reworkability in view of the increase of the member price and the waste of resources due to the recent enlargement of the screen.

Patent Document 1: Korean Patent Publication No. 2009-0077038

It is an object of the present invention to provide a double-faced pressure-sensitive adhesive sheet which is easily peeled from inside of a sheet without using heat or a semi-crosslinking method, and which has excellent reworkability and an image display apparatus having the same.

It is still another object of the present invention to provide a double-sided pressure-sensitive adhesive sheet having excellent heat resistance and heat and humidity resistance, and an image display apparatus having the same.

1. A transparent structure comprising a first transparent substrate, a second transparent substrate, and a transparent adhesive layer interposed between the transparent substrates,

Wherein the transparent adhesive layer has a peel force of 0.1 to 5 N / 25 mm at a peeling speed of 300 mm / min.

2. The double-sided pressure-sensitive adhesive sheet according to 1 above, wherein the transparent adhesive layer has a thickness of 0.01 to 20 탆.

3. The transparent adhesive layer as described in 1 above, wherein the transparent adhesive layer comprises 1 to 10 parts by weight of an acetoacetyl group-modified polyvinyl alcohol-based resin per 100 parts by weight of the solvent and 100 parts by weight of the solvent, and 1 to 10 parts by weight of the acetoacetyl modified polyvinyl alcohol Based pressure-sensitive adhesive sheet is formed from an adhesive layer-forming composition comprising 10 to 50 parts by weight of glyoxal based on 100 parts by weight of a base resin.

4. The thermoplastic resin composition according to item 1, wherein the first transparent material and the second transparent material are independently selected from a polyester resin, a cellulose resin, a polyolefin resin, a (meth) acrylate resin, a styrene resin, a polycarbonate resin, Based resins, amide-based resins, imide-based resins, sulfone-based resins, polyether sulfone-based resins, polyetheretherketone-based resins, polyphenylene sulfide-based resins, vinyl alcohol-based resins, vinylidene chloride- Sided pressure-sensitive adhesive sheet is formed of at least one selected from the group consisting of a polyurethane resin, a polyurethane resin, a polyurethane resin, a polyurethane resin, a polyurethane resin, a polyurethane resin,

5. The thermoplastic resin composition according to item 1, wherein the first transparent material and the second transparent material are independently formed of at least one selected from the group consisting of a polyester resin, a cellulose resin, a polyolefin resin and a (meth) acrylate resin Double-sided adhesive sheet.

6. The double-sided pressure-sensitive adhesive sheet according to 1 above, wherein the first transparent substrate and the second transparent substrate are independently of each other in thickness of 5 to 100 탆.

7. The double-faced pressure-sensitive adhesive sheet according to 1 above, wherein the first transparent substrate and the second transparent substrate have a transparent adhesive layer and a first adhesive layer and a second adhesive layer respectively on opposite sides of the attached surface.

8. The double-sided pressure-sensitive adhesive sheet according to 7 above, wherein the first adhesive layer and the second adhesive layer are formed of a transparent adhesive for optics comprising a urethane (meth) acryl oligomer, a reactive diluent monomer and a photopolymerization initiator.

9. The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 8, wherein the urethane (meth) acryl oligomer is a monofunctional urethane (meth) acryl oligomer.

10. The double-sided pressure-sensitive adhesive sheet according to item 8, wherein the urethane (meth) acryl oligomer has 3 to 15 urethane bonds.

11. The composition of claim 8, wherein the reactive diluent monomer is selected from the group consisting of n-butyl (meth) acrylate, 2-butyl (meth) acrylate, (Meth) acrylate, ethyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n- (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-methylbutyl (Meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, octadecyl (meth) acrylate, isobonyl (Meth) acrylate, 2-dodecylthioethyl (meth) acrylate, lauryl (Meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, At least one member selected from the group consisting of acrylate, allyl (meth) acrylate, stearyl (meth) acrylate, phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate and acryloylmorpholine (Meth) acrylate-based monomers.

12. The double-sided pressure-sensitive adhesive sheet according to the above 8, wherein the reactive diluent monomer is at least one monofunctional (meth) acrylate-based monomer selected from the group consisting of isobornyl acrylate and acryloylmorpholine.

13. An image display apparatus comprising the double-faced pressure-sensitive adhesive sheet according to any one of 1 to 12 above.

14. The image display apparatus according to 13 above, wherein one surface of the double-sided pressure-sensitive adhesive sheet is adhered to the protective glass and the other surface is adhered to the display module or the touch sensor module.

The double-sided pressure-sensitive adhesive sheet of the present invention does not use heat or semi-crosslinked resin in the process of peeling in the sheet, and peeling occurs easily in the sheet by applying a specific peeling force, so that the reworkability is excellent. Therefore, in the step of adhering two different members using the double-faced pressure-sensitive adhesive sheet of the present invention, even if there is some error in the adhering position, it is possible to easily attach and detach and reattach. Accordingly, it is possible to reduce the waste of resources and the production cost in the manufacturing process.

Further, the double-sided pressure-sensitive adhesive sheet of the present invention is excellent in heat resistance and heat and humidity resistance that the double-sided pressure-sensitive adhesive sheet should basically have, and can be easily applied to various image display apparatuses currently produced.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic cross-sectional view of a transparent structure in which a transparent adhesive layer according to the present invention is sandwiched between different transparent materials, and schematically shows an embodiment of a mechanism in which a transparent adhesive layer is peeled.
2 is a schematic cross-sectional view of one embodiment of a double-sided pressure-sensitive adhesive sheet of the present invention.

The present invention provides a transparent structure comprising a first transparent substrate, a second transparent substrate, and a transparent adhesive layer interposed between the transparent substrates, wherein the transparent adhesive layer has a peeling force of 0.1 to 5 N / 25 mm, which is excellent in reworkability and is easy to repeatedly peel and re-stick, and an image display apparatus having the double-sided pressure-sensitive adhesive sheet.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The double-sided pressure-sensitive adhesive sheet of the present invention comprises a transparent structure having a transparent adhesive layer interposed between a first transparent material and a second transparent material, wherein the transparent adhesive layer has a peeling force of 0.1 to 5 N / 25 mm.

Fig. 1 schematically shows an embodiment in which the transparent structure and the transparent adhesive layer are peeled off in the present invention. As shown in FIG. 1, when the transparent adhesive layer of the double-sided pressure-sensitive adhesive sheet has a peeling force in the above-described specific range, a notch is made using a knife without any additional process such as heat treatment, And it is evident that peeling of the entire surface easily occurs almost simultaneously, and re-adhesion after peeling is also easy. Due to the fact that peeling is possible through such a simple physical action, even if the object to be adhered by the double-faced pressure-sensitive adhesive sheet of the present invention is a glass substrate with a large size or little flexibility, rework can be easily performed without causing damage to the substrate .

The transparent adhesive layer 100 according to the present invention preferably has a peeling force of 0.1 to 5 N / 25 mm at a peeling speed of 300 mm / min. If the peeling force is less than 0.1 N / 25 mm, peeling may occur at an excessively low peeling force, so that the adhesive performance of the adhesive layer may be deteriorated. If the peeling force is more than 5 N / 25 mm, excessive force is applied to peeling, May be damaged.

The transparent adhesive layer 100 preferably has a thickness of 0.01 to 20 占 퐉 in view of ensuring the adhesion and showing easy peeling.

The transparent adhesive layer 100 according to the present invention can be applied to the present invention without any particular limitation, as long as it has the aforementioned peeling force range. As an embodiment for forming the transparent adhesive layer 100 of the present invention, for example, a transparent adhesive layer of the present invention may be formed of a composition for forming an adhesive layer containing an acetoacetyl group-modified polyvinyl alcohol-based resin, glyoxal and a solvent .

The acetoacetyl group-modified polyvinyl alcohol-based resin may be contained in the composition in an amount of 1 to 10 parts by weight, preferably 1 to 8 parts by weight, more preferably 3 to 5 parts by weight based on 100 parts by weight of the solvent. When the vinyl alcohol-based resin is less than 1 part by weight based on 100 parts by weight of the solvent, the adhesiveness tends to decrease. When the vinyl alcohol-based resin is more than 10 parts by weight, the optical performance of the transparent substrate tends to decrease.

The weight ratio of the acetoacetyl group-modified polyvinyl alcohol-based resin to glyoxal is 10 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol-based resin on a solid basis, , And more preferably 10 to 20 parts by weight. When the weight ratio of glyoxal to the acetoacetyl group-modified polyvinyl alcohol-based resin is less than 10 parts by weight, it is difficult to sufficiently express the durability of the adhesive layer, and the weight ratio of glyoxal to the acetoacetyl group-modified polyvinyl alcohol- If the amount is more than 50 parts by weight, the adhesion between the transparent materials is too high, and the nicking property is not sufficiently secured.

As the solvent, water, alcohol, or a mixed solvent thereof can be used. As the alcohol, a lower alcohol having 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms can be used.

The double-faced pressure-sensitive adhesive sheet of the present invention may include a transparent structure having a first transparent substrate 121 on one side of the transparent adhesive layer 100 and a second transparent substrate 122 on the opposite side. The first transparent substrate 121 and the second transparent substrate 122 are supported by the transparent adhesive layer 100 and are separated when the transparent adhesive layer 100 is peeled to form outermost surfaces of two different members.

The transparent substrates 121 and 122 are preferably excellent in transparency, mechanical strength, thermal stability, and the like. For example, at least one selected from the group consisting of a cellulose-based resin, a cycloolefin-based resin, a polyethylene terephthalate-based resin and a (meth) acrylate-based resin. Examples of the protective film include a polyester resin such as polyethylene terephthalate and polyethylene naphthalate, a cellulose resin such as diacetyl cellulose and triacetyl cellulose, a (meth) acrylate resin such as polymethyl methacrylate, Styrene-based resins such as polystyrene and acrylonitrile-styrene copolymer (AS resin), and polycarbonate-based resins. Further, polyolefin resins such as polyethylene, polypropylene, polyolefin resins such as a polyolefin or an ethylene-propylene copolymer having a cyclic or norbornene structure, vinyl chloride resins, amide resins such as nylon and aromatic polyamides, imide resins, Polyether ether ketone resin, polyphenylene sulfide resin, vinyl alcohol resin, vinylidene chloride resin, vinyl butyral resin, allylate resin, polyoxymethylene resin, polyether sulfone resin, Epoxy resin, or a blend of the resin may also be mentioned as an example of the resin forming the transparent substrates 121 and 122.

A polyester resin, a cellulose resin, a polyolefin resin and a (meth) acrylate resin are preferable from the viewpoints of transparency, compatibility and mechanical characteristics of the double-sided pressure-sensitive adhesive sheet, more preferably triacetylcellulose resin . The thickness of the transparent substrates 121 and 122 is preferably 5 to 100 占 퐉. If the thickness is less than 5 mu m, it is necessary to form a thick transparent adhesive layer in order to increase the impact resistance of the image display apparatus, so that it becomes difficult to manufacture the double-faced pressure-sensitive adhesive sheet, and the yield of the pressure- There is no effect of increasing the thickness further, and the overall thickness of the image display apparatus can be excessively thick.

In the double-sided pressure-sensitive adhesive sheet of the present invention, the first transparent substrate and the second transparent substrate are respectively provided with a first adhesive layer and a second adhesive layer on opposite sides of the transparent adhesive layer and the attached surface, respectively. An embodiment of the double-sided pressure-sensitive adhesive sheet of the present invention having an adhesive layer on a transparent substrate is schematically shown in Fig.

The adhesive layers 131 and 132 form an adhesion with an object to which the double-sided adhesive sheet of the present invention is adhered. The adhesive layers 131 and 132 can be formed using any transparent adhesive for optical (OCA) in the art without any particular limitation. Preferably, a pressure-sensitive adhesive containing a urethane (meth) acryl oligomer, a reactive diluent monomer and a photopolymerization initiator can be exemplified.

Urethane (meth) acrylate oligomer is a component for imparting physical properties as a pressure-sensitive adhesive, and a urethane (meth) acrylate oligomer can be generally produced using a polyester polyol and a polyether polyol. Among them, a polyether polyol is preferable to have a high molecular weight and a low viscosity, and it is particularly preferable to prepare a urethane (meth) acrylate oligomer with polypropylene glycol having a molecular weight of 800 to 4,500 as a main chain.

In addition, the urethane (meth) acrylate oligomer of the present invention is preferably a monofunctional urethane (meth) acrylate oligomer that is not polyfunctional. In the case of using a polyfunctional urethane (meth) acrylate oligomer, the tacky property of the surface of the pressure-sensitive adhesive layer is lowered and the cohesive force is excessively increased, so that the adhesive property is not easily manifested.

The monofunctional urethane (meth) acrylate oligomer can be obtained by the reaction of a polypropylene glycol having an molecular weight of 800 to 4,500, an isocyanate compound and a hydroxyl group-containing (meth) acrylate monomer.

Polypropylene glycol contains a methyl group and when it is oligomerized, it interferes with hydrogen bonding between urethane bonds to control the viscosity of the pressure-sensitive adhesive composition to a low level. The polypropylene glycol preferably has a molecular weight of 800 to 4,500. If the molecular weight is less than 800, the urethane bond may increase and the viscosity may be increased in the process of increasing the molecular weight of the oligomer. If the molecular weight is more than 4,500, the soft segment (amorphous) polypropylene glycol moiety is too much in the oligomer molecule, And the heat resistance and anti-wet heat resistance may be weakened.

The kind of the isocyanate compound is not particularly limited, and examples thereof include isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate, Bis (4-isocyanatoethyl) isocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, 2,2-bis-4'-propane isocyanate, Hexane diisocyanate, 4,4'-diphenylene diisocyanate, 3,3'-dimethylphenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, p- Naphthalene diisocyanate, 1,4-naphthalene diisocyanate, 1,4-xylene diisocyanate, 1,3-xylene diisocyanate, cyclopentylene-1,3-diisocyanate Diisobutylmethane diisocyanate, cyclohexene-1,4-diisocyanate, 4,4'-methylenebis (phenylisocyanate), 2,2-diphenylpropane-4,4'-di Diisocyanate, tetramethylenediene diisocyanate, 1-chlorobenzene-2,4-diisocyanate, and oligomers thereof. Of these, isophorone diisocyanate, 1,6- Hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and the like. These may be used alone or in combination of two or more.

The kind of the hydroxy group-containing (meth) acrylate monomer is not particularly limited, and examples thereof include hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypropyl (meth) acrylate, (Meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyethyleneglycol (meth) acrylate, hydroxypropyleneglycol ) Acrylate is preferable. These may be used alone or in combination of two or more.

The method for producing the monofunctional urethane (meth) acrylate oligomer is not particularly limited, and a one-shot method or a prepolymer method can be generally used. For example, the one-shot method is a method in which polypropylene glycol, a (meth) acrylate monomer having a hydroxy group and a primary alcohol are mixed, and then an isocyanate compound is reacted with an isocyanate compound in an appropriate equivalent ratio, (Meth) acrylate oligomer. The prepolymer method is a method in which a polypropylene glycol and an isocyanate compound are mixed and a polypropylene glycol is reacted with an isocyanate group [-NCO] of an isocyanate compound to obtain a urethane bond-containing prepolymer, and then a (meth) acrylate having a hydroxy group (Meth) acrylate oligomer by reacting a solution prepared by mixing monomers and a primary alcohol in an equivalent ratio of 1: 1.

The monofunctional urethane (meth) acrylate oligomer preferably has 3 to 15 urethane bonds. If the number of urethane bonds is less than 3, it may be difficult to produce a homogeneous composition and the cohesive force may be weakened. If the urethane bond is more than 15, the cohesive strength may become too high, and initial tackiness may deteriorate. At this time, the number of urethane bonds can be controlled by considering the molecular weight of the polypropylene glycol and the weight average molecular weight of the monofunctional urethane (meth) acrylate oligomer to be produced.

The weight average molecular weight of the monofunctional urethane (meth) acrylate oligomer affects the adhesive strength and viscosity. Usually, when the weight average molecular weight is smaller, the viscosity is lowered but the adhesive strength is lowered. On the other hand, . In the present invention, the weight average molecular weight is preferably 5,000 to 30,000, more preferably 10,000 to 30,000. When the weight average molecular weight is less than 5,000, the viscosity is too low to provide good coating properties, and it may be difficult to obtain the effect of the use of the diluted monomer. When the weight average molecular weight is more than 30,000, the viscosity becomes too high and the handling property is poor.

The viscosity of the monofunctional urethane (meth) acrylate oligomer is preferably 10,000 to 300,000 cPs, more preferably 10,000 to 150,000 cPs. If the viscosity is less than 10,000 cPs, it is difficult to control the proper coating viscosity by using a diluting monomer. If the viscosity is more than 300,000 cPs, it may be difficult to control the adhesion and durability by using an excessively dilute monomer to obtain an appropriate viscosity.

The monofunctional urethane (meth) acrylate oligomer is preferably contained in an amount of 30 to 80% by weight, more preferably 40 to 75% by weight, based on 100% by weight of the total amount of the adhesive composition for optical use. When the content is less than 30% by weight, the viscosity of the pressure-sensitive adhesive composition is low and the coating property is poor. When the content is more than 80% by weight, the viscosity increases and the processability may be deteriorated.

The reactive diluent monomer is preferably a monofunctional (meth) acrylate monomer as a monomer having a functional group capable of crosslinking with a monofunctional urethane (meth) acrylate oligomer while controlling the viscosity of the adhesive composition which is a solventless type.

The monofunctional (meth) acrylate monomer is not particularly limited, and examples thereof include n-butyl (meth) acrylate, 2-butyl (meth) acrylate, (Meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (Meth) acrylate, n-octyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (Meth) acrylate, isoamyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, octadecyl (Meth) acrylate, dodecyl (meth) acrylate, 2-dodecylthio Acrylates such as ethyl (meth) acrylate, lauryl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, (Meth) acrylate, hydroxybutyl (meth) acrylate, allyl (meth) acrylate, stearyl (meth) acrylate, phenoxyethyl (meth) acrylate, tetrahydrofurfuryl And monomorpholine. Of these, isobornyl acrylate, acryloylmorpholine, or a mixture thereof may be preferably used. These may be used alone or in combination of two or more.

As the reactive diluent monomer, a monofunctional (meth) acrylate monomer, a trifunctional (meth) acrylate monomer, or a mixture thereof may be used in combination with a monofunctional (meth) acrylate monomer within the range not hindering the effect of the present invention They can be used in small amounts. Examples of the bifunctional (meth) acrylate monomers include 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, (Meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (Meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dicyclopentanyl di (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol hexa (Meth) acrylate, trimethylolpropane di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentyl (meth) acrylate, Glycol-modified trimethylolpropane di (meth) acrylate, adamantanedi (meth) acrylate, and the like. Examples of the trifunctional (meth) acrylate monomers include trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (Meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, glycerol Tri (meth) acrylate, and the like. These may be used alone or in combination of two or more.

The reactive diluent monomer is preferably contained in an amount of 5 to 60% by weight, more preferably 10 to 50% by weight, and most preferably 20 to 45% by weight based on 100% by weight of the total amount of the adhesive composition for optical use. If the content is less than 5% by weight, the curing rate may be lowered, and if it is more than 60% by weight, curing shrinkage may occur seriously and the coating property may be deteriorated.

The photopolymerization initiator is a component for sufficiently accelerating not only the interior of the coated adhesive composition but also the surface hardening, and the kind thereof is not particularly limited as long as it is known in the art. Specific examples thereof include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, hydroxydimethylacetophenone, dimethylaminoacetophenone, Dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 4-chromolocetophenone, 4, 4-dimethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4-hydroxycyclophenyl ketone, 1- hydroxycyclohexyl phenyl ketone, (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenyl Benzophenone, 4,4-diaminobenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, anthraquinone, 2-methyl anthraquinone, 2-ethyl anthraquinone, 2- 2-amino anthraquinone, 2-me 2-ethylhexanoate, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal, diphenylketone benzyldimethylketal, acetophenone Dimethyl ketal, p-dimethylaminobenzoic acid ester, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, fluorene, triphenylamine, carbazole and the like. Further, commercially available products such as Darocure 1173, Irgacure 184, Irgacure 907, Irgacure 1700 and TPO-L (BASF) can also be used. These may be used alone or in combination of two or more.

The photopolymerization initiator is preferably contained in an amount of 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, based on 100% by weight of the total amount of the pressure-sensitive adhesive composition for optical use. When the content is less than 0.1% by weight, the curing rate is slowed and sufficient curing may be difficult to proceed. If the content is more than 10% by weight, the molecular weight of the polymer to be photopolymerized may be small and durability may be deteriorated.

The double-sided pressure-sensitive adhesive sheet according to the present invention preferably has a transmittance of about 90% or more and a haze of about 1.5 or less. More preferably, the transmittance is about 92% or more, and the haze can be set to about 1 or less. When the transmittance is less than 90% or the haze is more than 1.5, the visibility of the image display apparatus is deteriorated.

The double-sided pressure-sensitive adhesive sheet of the present invention may have release films 201 and 202 on the surfaces of the pressure-sensitive adhesive layers 131 and 132 for the convenience of storage and transportation. The release films 201 and 202 may be used without any particular limitation, as a release film conventionally used in the art. For example, a polyethylene terephthalate film coated with a silicone release agent can be used.

The double-sided pressure-sensitive adhesive sheet of the present invention can be applied to various types of image display devices such as a liquid crystal display (LCD), a plasma display panel (PDP), an organic electroluminescence display (OLED) And can be usefully used for manufacturing. For example, between the backlight unit and the liquid crystal panel, or between the display module and the protective glass. Since the double-sided pressure-sensitive adhesive sheet of the present invention has excellent reworkability, loss of cost and time during the manufacturing process can be remarkably reduced.

An embodiment of a method of mounting the double-sided adhesive sheet of the present invention between the display module and the protective glass will be briefly described as follows.

First, the second release film 202 is removed and the second adhesive layer 132 is adhered to the display module or the touch sensor module. Next, the first release film 201 is removed and a protective glass is adhered to the first adhesive layer 131. There are two possible methods for bonding the protective glass. As a first method, first, the protective glass is disposed on the first adhesive layer 131 of the double-sided adhesive sheet bonded to the display module. Then, a vacuum is applied and a uniform pressure is applied to the entire upper surface of the protective glass, and the pressure is applied toward the display module. Then, the first adhesive layer 131 of the display module and the protective glass are adhered to each other without breaking the protective glass. As a second method, the first adhesive layer 131 and the protective glass are first brought into contact with each other, and then the protective glass is pressed using a roll sticking method. In this case, although the protection glass is not flexible, the protection glass 120 is prevented from being damaged, so that the adhesion can be efficiently performed.

Sensitive adhesive sheet 100 according to the present invention, the transparent substrates 121 and 122, the adhesive layers 131 and 132, and the adhesive layers 131 and 132, respectively, when the double-sided adhesive sheet of the present invention is interposed between the display module and the protective glass. May have a refractive index in the range of about 1.47 to 1.55, preferably 1.49 to 1.53, which is similar to that of the protective glass. When the refractive index is less than 1.47 or more than 1.55, the refractive index difference with respect to the protective glass becomes large, and the effect of improving the visibility of the image display device can not be obtained.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Example  One

≪ Preparation of composition for forming transparent adhesive layer >

An aqueous solution of 10% concentration was prepared by dissolving an acetoacetyl group-modified polyvinyl alcohol-based resin (trade name: "KOSENOL Z200", 4% aqueous solution, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) in pure water. The aqueous solution of the acetoacetyl group-modified polyvinyl alcohol resin and the glyoxal crosslinking agent are mixed so that the weight ratio of the former solids is 100: 10. The weight ratio of the water / alcohol mixed solvent to the water / alcohol mixed solvent was adjusted so that the weight ratio of the water / alcohol mixed solvent to the water / alcohol mixed solvent was 3 parts by weight based on 100 parts by weight of the alcohol / And diluted with a mixed solvent to prepare a composition for forming a transparent adhesive layer.

≪ Preparation of transparent pressure-sensitive adhesive for optical &

1. Urethane ( Meta ) Acrylate Oligomeric  Produce

A 10 L four-necked flask equipped with a thermometer and a stirrer and capable of nitrogen reflux was immersed in an oil bath. To the flask was added 3038 g of polypropylene glycol having a molecular weight of 4,000 (Sanenix PP-4000, manufactured by Samyang Chemical Industry Co., Ltd.), isophorone diisocyanate And 0.3 g of dibutyltin dilaurate as a urethanization catalyst were charged and stirred at a reaction temperature of 60 캜 for 2 hours to obtain a urethane prepolymer. Subsequently, the reaction temperature was lowered to 40 占 폚, and then 0.3 g of dibutyltin dilaurate as a urethanation catalyst and 0.5 g of 2,6-t-butyl 4-methylphenol (BHT) as a polymerization inhibitor were added thereto. And 88 g of 2-hydroxyethyl acrylate (Osaka Organic Chemical Industry Co., Ltd.) were slowly dropped for 30 minutes. Then, the reaction temperature was raised to 70 캜 and stirred to obtain a monofunctional urethane acrylate oligomer having a weight average molecular weight of 26,600.

2. Manufacture of Adhesive

A pressure sensitive adhesive was prepared by mixing 67 wt% of the monofunctional urethane (meth) acrylate oligomer, 15 wt% of acryloylmorpholine, 15 wt% of isobornyl acrylate, and 2.0 wt% of photopolymerization initiator (Darocure 1173).

<Production of double-faced pressure-sensitive adhesive sheet>

(1) The transparent adhesive layer-forming composition prepared above was applied to a saponified triacetylcellulose film (KC4UYW, Konica Film) having a thickness of 40 탆, and another 40 탆 triacetylcellulose film, which was the same company product, was bonded thereto . This was dried for 3 minutes at a temperature of 60 캜 to prepare a transparent base structure having a transparent adhesive layer interposed between the transparent substrates (thickness of the adhesive layer: about 0.1 탆).

(2) The optical transparent pressure-sensitive adhesive prepared above was cured on one transparent film coated with a silicone release agent on a polyethylene terephthalate (PET) film, and then coated with polyethylene terephthalate (PET) The film was covered with another transparent film coated with a silicone release agent and made into a sheet state. Ultraviolet rays (600 mJ / cm 2) were irradiated at a speed of 4 m / min and fully cured to prepare a sheet for adhesion. To prepare two sheets for bonding.

(3) The release film of the first spotting sheet produced in (2) was removed, and the transparent substrate structure produced in (1) was bonded to the exposed adhesive layer. And the exposed adhesive layer was bonded to the transparent base structure to prepare a double-sided pressure-sensitive adhesive sheet having a transparent structure interposed therebetween.

Example  2-3 and Comparative Example  1-3

A double-sided pressure-sensitive adhesive sheet was prepared in the same manner as the above-mentioned method except that the composition for forming a transparent adhesive layer was prepared with the composition shown in Table 1 below.

Peel force  Measure

The peel strengths of the double-faced pressure-sensitive adhesive sheets produced in Examples and Comparative Examples were measured under the following conditions.

The specimen for the peeling force measurement was prepared in such a manner that the composition for forming a transparent adhesive layer was prepared with the composition shown in Table 1 below and the transparent substrates 121 and 122 were cut into a width of 50 cm x 20 cm and then a transparent adhesive was cut in half , A transparent substrate was again bonded thereon and then dried at 60 ° C for 3 minutes to prepare a transparent structure having a transparent adhesive layer interposed between the different transparent substrates. The double-faced pressure-sensitive adhesive sheet was produced by bonding the backing-wearing sheet back and forth. The double-faced pressure-sensitive adhesive sheet was cut into 20 cm x 25 mm using a super cutter and adhered to each jig portion in a 90 degree peel manner using an intrinsic tester 5567 And the peel force was measured at 300 mm / min.

Composition for forming a transparent adhesive layer
Peel force
(N / 25 mm) Resin content
(Solvent: resin) Crosslinker content
(Resin: crosslinking agent) menstruum
(Water: ethanol) Example 1 100: 3 100: 10 90:10 1.6 Example 2 100: 3 100: 20 90:10 3.4 Example 3 100: 5 100: 10 90:10 2.1 Comparative Example 1 100: 3 100: 30 90:10 0.05 Comparative Example 2 100: 3 100: 5 90:10 6.7 Comparative Example 3 100: 15 100: 20 90:10 Specimen cutting

In Table 1, Comparative Example 3 shows a case in which a part of the specimen which has been peeled without being peeled off in the peeling process is cut off and separated.

Experimental Example

The stickability, durability (heat resistance and heat and humidity resistance) and reworkability of the double-faced pressure-sensitive adhesive sheets of the prepared examples and comparative examples were evaluated and are shown in Table 2 below.

One. Notchability

The prepared double-faced pressure-sensitive adhesive sheets were allowed to stand at room temperature for 1 hour, and the cutter blade was inserted into the transparent pressure-sensitive adhesive layer on the side of the double-faced pressure-sensitive adhesive sheet.

○: When pushing the blade, the blade enters the transparent adhesive layer without any difficulty

DELTA: When the blade is pushed, it stops when the blade enters the transparent adhesive layer 4 to 5 mm.

X: The cutter blade does not enter the transparent adhesive layer

2. Durability (heat resistance and Humidity Durability )

The double-faced pressure-sensitive adhesive sheet thus produced was cut into A4 size, and one transparent film was peeled off and bonded to the glass plate. The bonded body was treated in an autoclave at 50 ° C and 5 atm for 20 minutes to prepare specimens. The durability of heat resistance was determined by observing the occurrence of bubbles or peeling on the bonding surface between the glass plate and the pressure-sensitive adhesive layer of the specimen, which was left in an oven at 80 ° C for 100 hours and then left for 100 hours in an oven at 60 ° C and 90% It was observed with naked eyes and evaluated based on the following criteria.

○: No bubble and peeling phenomenon in sample.

△: Some bubbles or peeling phenomenon exist in the sample.

×: There are many bubbles and peeling phenomenon in the sample

3. Re-workability

The produced double-sided pressure-sensitive adhesive sheet was cut to a size of 10 X 10 cm, and one release film was peeled off, and then bonded to the tempered glass plate. The opposite release film was peeled off and then bonded to the tempered glass plate. The bonded body was treated in an autoclave at 50 ° C and 5 atm for 20 minutes to prepare specimens. The notch is made artificially in the in-plane exfoliating substrate part by putting the blade at the edge part of the finished specimen and drawing the entire one corner part. One surface is fixed to the vacuum adsorption plate, and a vacuum adsorption plate is further provided at the corner portion of the opposite surface to cause in-plane separation.

○: Glass is not broken and in-plane peeling occurs

?: Partial in-plane peeling occurs but glass breaks

X: In-plane peeling does not occur.

Notchability durability Re-workability Example 1 ○ ○ ○ Example 2 ○ ○ ○ Example 3 ○ ○ ○ Comparative Example 1 ○ × △ Comparative Example 2 △ ○ × Comparative Example 3 × ○ ×

As shown in Table 2, in the case of the comparative examples in which the peeling force is out of the range of the present invention, noticeability, durability and reworkability are remarkably lower than those in Examples.

100: transparent adhesive layer
121: first transparent substrate 122: second transparent substrate
131: first adhesive layer 132: second adhesive layer
201: first release film 202: second release film

Claims (14)

A transparent structure comprising a first transparent substrate, a second transparent substrate, and a transparent adhesive layer interposed between the transparent substrates,
Wherein the first transparent substrate and the second transparent substrate have a first adhesive layer and a second adhesive layer on opposite sides of the transparent adhesive layer and the attached surface,
Wherein the transparent adhesive layer comprises 1 to 10 parts by weight of an acetoacetyl group-modified polyvinyl alcohol resin based on 100 parts by weight of a solvent and 100 parts by weight of the solvent, and 100 to 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol- And 10 to 50 parts by weight of glyoxal,
Wherein the transparent adhesive layer has a peel force of 0.1 to 5 N / 25 mm at a peeling speed of 300 mm / min.
The double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the transparent adhesive layer has a thickness of 0.01 to 20 μm.
delete [2] The method according to claim 1, wherein the first transparent substrate and the second transparent substrate are independently formed of a polyester resin, a cellulose resin, a polyolefin resin, a (meth) acrylate resin, a styrene resin, a polycarbonate resin, Based resins, amide-based resins, imide-based resins, sulfone-based resins, polyether sulfone-based resins, polyetheretherketone-based resins, polyphenylene sulfide-based resins, vinyl alcohol-based resins, vinylidene chloride- , An allylate-based resin, a polyoxymethylene-based resin, an epoxy-based resin, and a blend of the resins.
[2] The method according to claim 1, wherein the first transparent substrate and the second transparent substrate are independently formed of at least one selected from the group consisting of a polyester resin, a cellulose resin, a polyolefin resin, and a (meth) Sheet.
The double-faced pressure-sensitive adhesive sheet according to claim 1, wherein the first transparent substrate and the second transparent substrate are independently of each other in thickness of 5 to 100 탆.
delete The double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the first adhesive layer and the second adhesive layer are formed of a transparent adhesive for optics comprising a urethane (meth) acryl oligomer, a reactive diluent monomer and a photopolymerization initiator.
The double-faced pressure-sensitive adhesive sheet according to claim 8, wherein the urethane (meth) acryl oligomer is a monofunctional urethane (meth) acryl oligomer.
The double-sided pressure-sensitive adhesive sheet according to claim 8, wherein the urethane (meth) acryl oligomer has 3 to 15 urethane bonds.
[9] The method of claim 8, wherein the reactive diluent monomer is selected from the group consisting of n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t- butyl (meth) acrylate, isobutyl (meth) (Meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, pentyl (meth) acrylate, n (Meth) acrylate, isoamyl (meth) acrylate, isoamyl (meth) acrylate, isoamyl (meth) acrylate, (meth) acrylate, isodecyl (meth) acrylate, octadecyl (meth) acrylate, isobornyl (meth) acrylate, 4-methyl- (Meth) acrylate, 2-dodecylthioethyl (meth) acrylate, lauryl (Meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, hydroxyethyl At least one member selected from the group consisting of (meth) acrylate, allyl (meth) acrylate, stearyl (meth) acrylate, phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate and acryloylmorpholine And a monofunctional (meth) acrylate monomer.
The double-sided pressure-sensitive adhesive sheet according to claim 8, wherein the reactive diluent monomer is at least one monofunctional (meth) acrylate monomer selected from the group consisting of isobornyl acrylate and acryloyl morpholine.
An image display apparatus comprising the double-sided pressure-sensitive adhesive sheet according to any one of claims 1, 2, 4 to 6, and 8 to 12.
14. The image display apparatus according to claim 13, wherein one surface of the double-sided pressure-sensitive adhesive sheet is adhered to the protective glass and the other surface is adhered to the display module or the touch sensor module.

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