KR20190024305A - Adhesive composition and adhesive layer comprising cured product of the same - Google Patents

Abstract

The present invention relates to an adhesive composition and an adhesive layer comprising a cured product thereof. The adhesive composition comprises: a viscous copolymer obtained by copolymerizing an alkyl group-containing (meth)acrylate monomer, a cycloalkyl group-containing (meth)acrylate monomer, a polar functional group-containing (meth)acrylate monomer, and an N-vinyl pyrrolidone monomer; a curing agent; and a solvent, wherein the weight average molecular weight of the viscous copolymer is 1,100,000-1,300,000 g/mol. In addition, the adhesive layer has excellent durability at high temperature and high humidity.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pressure-sensitive adhesive composition comprising a pressure-sensitive adhesive composition and a cured product of the pressure-

The present invention provides a pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer containing a cured product thereof, and a display device including the pressure-sensitive adhesive layer.

Various members are attached to the electronic device by the adhesive layer. For example, various optical members such as a polarizing plate, a retardation plate, an optical compensation film, a reflection sheet, a protective film and a brightness enhancement film can be attached to a liquid crystal display (LCD) by a pressure sensitive adhesive layer. 2. Description of the Related Art In recent years, attempts have been made to realize excellent durability while reducing the thickness of a pressure-sensitive adhesive layer for attaching members in electronic devices as the thickness of electronic devices is reduced.

The window deco film (WDF) is a film that implements a color pattern according to the design of a display device, for example, a portable display device, or implements a print pattern to cover the internal wiring. It is a film that is required for a variety of product designs to be. Especially, in the case of smartphone, there is a large screen in the front, and the case structure except the screen is simple, so there is a limitation in containing design elements. Placing a particular appliance or machining a case can make it thicker or difficult for a consumer to use the appliance. In addition, the larger the screen occupying the front, the smaller the area of the bezel, the texture of the bezel's periphery and the backside, and the color surface became important factors. In recent years, it has become difficult to apply the conventional ink direct printing method by using a 3D structure glass on the front and rear sides by applying a bent panel instead of a 2D panel. As a result, a window deco film has been developed which is printed on a film substrate in a pattern and color and adhered to the 3D panel. The window deco film includes a pressure sensitive adhesive layer which is easy to adhere.

The pressure-sensitive adhesive layer may be obtained by coating the pressure-sensitive adhesive composition, followed by drying and aging. The step of storing the pressure-sensitive adhesive layer at a predetermined temperature so that the crosslinking reaction in the pressure-sensitive adhesive layer can be terminated is referred to as an aging process. In the course of aging, the physical properties of the pressure-sensitive adhesive layer such as adhesive force change with time. The peeling force after the above aging process is called build-up peeling force, which may affect the durability of the product to which the pressure-sensitive adhesive layer is applied.

Furthermore, as mentioned above, the demand for a curved surface display device is rapidly increasing, and a window deco film or the like is attached to a curved surface portion using a pressure-sensitive adhesive layer. However, in the case of the conventional pressure sensitive adhesive layer, the buildup peeling force is low, which may cause a floating phenomenon when applied to the curved surface portion of the display device.

Therefore, there is a need for studies on a pressure-sensitive adhesive layer having excellent durability and appearance and high build-up peel strength.

The present invention is intended to provide a pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition, and a pressure-sensitive adhesive layer.

It should be understood, however, that the present invention is not limited to the above-mentioned problems and other problems which are not mentioned can be understood by those skilled in the art from the following description.

One embodiment of the present invention relates to a pressure-sensitive adhesive composition obtained by copolymerizing an alkyl group-containing (meth) acrylate monomer, a cycloalkyl group-containing (meth) acrylate monomer, a polar functional group-containing (meth) acrylate monomer, and an N-vinylpyrrolidone monomer Copolymer; Curing agent; And a solvent, wherein the viscous copolymer has a weight average molecular weight of 1,100,000 g / mol to 1,300,000 g / mol.

An embodiment of the present invention provides a pressure-sensitive adhesive layer comprising a cured product of the pressure-sensitive adhesive composition.

An embodiment of the present invention provides a display device including the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive layer according to one embodiment of the present invention has a significantly high build-up peeling force as compared with the initial peeling force, and can prevent floating of the curved surface portion when applied to a curved display device.

The pressure-sensitive adhesive layer according to one embodiment of the present invention is advantageous in high temperature and high humidity durability.

In this specification, when a part is referred to as "including " an element, it is to be understood that it may include other elements as well, without departing from the other elements unless specifically stated otherwise.

In the present specification, the term "monomeric polymerization unit" may mean a form in which the monomer undergoes a polymerization reaction to form a skeleton of the polymer, for example, a main chain or a side chain.

In this specification, the unit "weight part" may mean the ratio of the weight between each component.

In the present specification, (meth) acrylate may mean acrylate or methacrylate.

In the present specification, the cycloalkyl group may include a carbon ring structure in which an unsaturated bond is not present in the functional group, and may include a monocyclic ring or a polycyclic ring having 2 to 20 carbon atoms. have.

In the present specification, the "peeling force" means that the produced pressure-sensitive adhesive layer is backed to a polyethylene terephthalate (PET) film and then attached to a glass substrate of 1.1 T thickness using a 2 kg roller, May be a value measured by ASTM D903 at a peel angle of 180 degrees under constant temperature and humidity conditions.

In the present specification, the weight average molecular weight (g / mol) may be a value in terms of polystyrene measured by gel permeation chromatography (GPC).

As used herein, "viscosity" may mean a value measured by a Brookfield viscometer with a 63 spindle under constant temperature and humidity conditions of 25 캜, 25 RH%.

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

One embodiment of the present invention relates to a pressure-sensitive adhesive composition obtained by copolymerizing an alkyl group-containing (meth) acrylate monomer, a cycloalkyl group-containing (meth) acrylate monomer, a polar functional group-containing (meth) acrylate monomer, and an N-vinylpyrrolidone monomer Copolymer; Curing agent; And a solvent, wherein the viscous copolymer has a weight average molecular weight of 1,100,000 g / mol to 1,300,000 g / mol.

According to an embodiment of the present invention, there is provided a process for producing a polymer (A), which comprises copolymerizing the alkyl group-containing (meth) acrylate monomer, the cycloalkyl group-containing (meth) acrylate monomer, the polar functional group- May be included as polymerized units of the adhesive copolymer, respectively.

According to one embodiment of the present invention, the viscous copolymer comprises a polymerized unit of an alkyl group-containing (meth) acrylate monomer, a polymerized unit of a cycloalkyl group-containing (meth) acrylate monomer, a polymerizable unit of a (meth) N-vinylpyrrolidone monomer may be contained.

According to one embodiment of the present invention, the content of the alkyl group-containing (meth) acrylate monomer may be the same as the content of the alkyl group-containing (meth) acrylate monomer.

According to one embodiment of the present invention, the content of the cycloalkyl group-containing (meth) acrylate monomer may be the same as the content of the polymerization unit of the cycloalkyl group-containing (meth) acrylate monomer.

According to one embodiment of the present invention, the content of the polar functional group-containing (meth) acrylate monomer may be the same as the content of the (meth) acrylate monomer polymerization unit containing the polar functional group.

According to one embodiment of the present invention, the content of the N-vinyl pyrrolidone monomer may be the same as the content of the N-vinyl pyrrolidone monomer.

According to one embodiment of the present invention, the viscous copolymer comprises the alkyl group-containing (meth) acrylate monomer, the cycloalkyl group-containing (meth) acrylate monomer, the polar functional group-containing (meth) acrylate monomer, Or may be one prepared by solution polymerization of a composition comprising a vinyl pyrrolidone monomer.

According to one embodiment of the present invention, the weight average molecular weight (Mw) of the viscous copolymer may be 1,100,000 g / mol to 1,300,000 g / mol. When the weight average molecular weight of the pressure-sensitive adhesive copolymer is less than 1,100,000 g / mol, the pressure-sensitive adhesive layer produced using the pressure-sensitive adhesive composition may have a problem in that bubbles are generated in a high temperature and high humidity environment and durability is deteriorated. When the weight average molecular weight of the adhesive copolymer is more than 1,300,000 g / mol, defective appearance of the pressure-sensitive adhesive layer produced using the pressure-sensitive adhesive composition may occur, and the initial peel strength before the aging treatment may be compared with the build- The power increase rate may be small.

According to one embodiment of the present invention, the adhesive copolymer includes a polymerization unit derived from an N-vinylpyrrolidone monomer, so that the initial peeling force before the aging treatment can be greatly increased by increasing the buildup peeling force after aging treatment have.

According to one embodiment of the present invention, the content of the N-vinylpyrrolidone monomer may be 0.5 part by weight or more and 15 parts by weight or less based on 100 parts by weight of the total monomers forming the viscous copolymer.

When the content of the N-vinylpyrrolidone monomer is within the above range, the pressure-sensitive adhesive layer produced using the pressure-sensitive adhesive composition has a significantly increased build-up peel-off force after aging compared with the initial peel strength before the aging treatment, High humidity durability can be realized. Furthermore, when the content of the N-vinylpyrrolidone monomer is within the above range, the pressure-sensitive adhesive layer produced using the pressure-sensitive adhesive composition can exhibit excellent appearance characteristics.

According to one embodiment of the present invention, the alkyl group-containing (meth) acrylate monomer may be a (meth) acrylate having an alkyl group having 1 to 20 carbon atoms. (Meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n- Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, (Meth) acrylate, n-octyl (meth) acrylate, and isooctyl (meth) acrylate.

According to one embodiment of the present invention, the alkyl group-containing (meth) acrylate monomer may be one comprising methacrylate and (meth) acrylate having an alkyl group having 2 to 20 carbon atoms. Specifically, according to one embodiment of the present invention, the alkyl group-containing (meth) acrylate monomer may include methacrylate and 2-ethylhexyl (meth) acrylate.

According to one embodiment of the present invention, the alkyl group-containing (meth) acrylate monomer may serve as a base monomer of the adhesive copolymer.

According to one embodiment of the present invention, the content of the alkyl group-containing (meth) acrylate monomer is 60 parts by weight or more and 80 parts by weight or less, 100 parts by weight or more and 80 parts by weight or less, Or less, or 70 parts by weight or more and 80 parts by weight or less.

When the content of the alkyl group-containing (meth) acrylate monomer is within the above range, the weight average molecular weight of the viscous copolymer can be easily controlled within the above range, and the polymerization of the viscous copolymer can be facilitated.

According to one embodiment of the present invention, the cycloalkyl group-containing (meth) acrylate monomer is at least one selected from the group consisting of cyclohexyl acrylate (CHA), cyclohexyl methacrylate (CHMA), isobornyl acrylate (IBOA), isobornyl methacrylate (IBOMA), and 3,3,5-trimethylcyclohexylacrylate (TMCHA, 3,3,5-trimethylcyclohexylacrylate).

According to an embodiment of the present invention, the content of the cycloalkyl group-containing (meth) acrylate monomer may be 10 parts by weight or more and 30 parts by weight or less based on 100 parts by weight of the total monomers forming the adhesive copolymer. Specifically, the content of the cycloalkyl group-containing (meth) acrylate monomer may be 10 parts by weight or more and 20 parts by weight or less, or 12.5 parts by weight or more and 17.5 parts by weight or less, based on 100 parts by weight of the total monomers forming the adhesive copolymer .

When the content of the cycloalkyl group-containing (meth) acrylate monomer is within the above range, the initial peeling strength of the pressure-sensitive adhesive layer produced using the pressure-sensitive adhesive composition can be improved.

According to one embodiment of the present invention, the polar functional group-containing (meth) acrylate monomer may include at least one of a hydroxy group-containing (meth) acrylate monomer and a carboxyl group-containing (meth) acrylate monomer.

According to one embodiment of the present invention, the hydroxy group-containing (meth) acrylate monomer is at least one monomer selected from the group consisting of 2-hydroxyethyl (meth) acrylate, 2- hydroxypropyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate, 2-hydroxypropyleneglycol (meth) acrylate, 2-hydroxypropyleneglycol (meth) And the like.

According to one embodiment of the present invention, the carboxyl group-containing (meth) acrylate monomer includes at least one member selected from the group consisting of acrylic acid, methacrylic acid, 2-ethyl acrylic acid and β-CEA (2-CARBOXYETHYL ACRYLATE) can do.

According to one embodiment of the present invention, the content of the polar functional group-containing (meth) acrylate monomer may be 3 parts by weight or more and 20 parts by weight or less based on 100 parts by weight of the total monomers forming the adhesive copolymer. Specifically, the content of the polar functional group-containing (meth) acrylate monomer may be 3 parts by weight or more and 15 parts by weight or less, or 5 parts by weight or more and 10 parts by weight or less, based on 100 parts by weight of the total monomers constituting the viscous copolymer .

When the content of the (meth) acrylate monomer containing the polar functional group is within the above range, the cohesive force of the pressure-sensitive adhesive composition can be controlled to be not excessively high, and the high temperature and high humidity durability of the pressure-sensitive adhesive layer produced using the pressure- . When the content of the (meth) acrylate monomer containing a polar functional group is within the above range, the haze of the pressure-sensitive adhesive layer produced using the pressure-sensitive adhesive composition can be controlled to be low, and gelation of the pressure-sensitive adhesive composition can be prevented.

According to one embodiment of the present invention, the solid content of the pressure-sensitive adhesive composition may be 10% or more and 70% or less. Specifically, the solid content of the pressure-sensitive adhesive composition may be 20% or more, 25%, 21% or more, 23% or 22%.

According to one embodiment of the present invention, the viscosity of the pressure-sensitive adhesive composition at a solid content of 22% may be 2,500 cP or less. Specifically, the viscosity of the pressure-sensitive adhesive composition at a solid content of 22% may be 2,300 cP or less.

The solid content of the pressure-sensitive adhesive composition can be controlled by adjusting the amount of the pressure-sensitive adhesive copolymer to be diluted in a solvent. The viscosity of the pressure-sensitive adhesive composition is appropriately controlled within the range of the solid content, Can be shortened.

According to one embodiment of the present invention, the curing agent may be a photo-curing agent or a thermosetting agent. Specifically, the curing agent may be a thermosetting agent.

According to one embodiment of the present invention, the content of the curing agent is 0.01 to 5 parts by weight, or 0.01 to 3 parts by weight, or 0.01 to 2 parts by weight, based on 100 parts by weight of the viscous copolymer, Or less.

When the content of the curing agent is within the above range, the pressure-sensitive adhesive composition is sufficiently cured to minimize the generation of steam, to achieve a high peeling force, and to lower the TML (Total Mass Loss) value.

According to one embodiment of the present invention, the photocuring agent is a benzophenone-based compound, an acetophenone-based compound, a nonimidazole-based compound, a triazine-based compound, a oxime-based compound, Can be used. Specific examples of the photocuring agent include benzophenone, benzoyl methyl benzoate, acetophenone, 2,4-diethyl thioxanthone, 2,4-diethyl thioxanthone, 2-chloro thioxanthone, ethyl anthraquinone, 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184 available from Ciba) Or 2-hydroxy-2-methyl-1-phenyl-propan-1-one can be used.

Specifically, the photo-curing agent was IRGACURE 250, IRGACURE 270 (manufactured by BASF), WPI-113, WPI-116, WPI-169, WPI-170, WPI-124, WPAG-638, WPAG- -367, WPAG-336 (manufactured by Wako Pure Chemical Industries, Ltd.), B2380, B2381, C1390, D2238, D2248, D2253, I0591, T1608, T1609, T2041, T2042 (manufactured by Tokyo Kasei Kogyo Co., SP-056, SP-066, SP-130, SP-1307, CP-1017, CP- 140, SP-150, SP-170, SP-171, and SP-172 (manufactured by ADEKA Corporation), CD-1010, CD- SI-100, SI-100L, SI-80L, SI-100L, SI-L145, SI-L150, SI-L160, SI-L110, SI-L147 (manufactured by SANSHIN KAGAKU KOGYO CO. PI2074 (manufactured by Rhodia Japan) or the like can be used. However, the present invention is not limited thereto, and photo-curing agents used in the art can be applied.

According to one embodiment of the present invention, the thermosetting agent may be a peroxide, an azo-based compound, or a mixture of two or more thereof. Specifically, the peroxide may be di-tert-butyl peroxide or di-tert-amyl peroxide, and the azo compound may be 2 , 2'-azobis (2-methyl-propane).

Specifically, the thermosetting agent is PP-33, CP-66, CP-77 (manufactured by ADEKA); FC-509 (made by 3M); Ube (UVE) 1014 (G. E.); Line Aid SI-60L, Sun Aid SI-80L, Sun Aid SI-100L, Sun Aid SI-110L, Sun Aid SI-150L, SI-B3 (manufactured by SANSHIN KAGAKU KOGYO CO., LTD.); CG-24-61 (BASF); TA-60, TA-100, TA-120, and TA-160 (manufactured by SAN-APRO CO., LTD.). However, the present invention is not limited thereto, and a thermosetting agent used in the art can be applied.

According to one embodiment of the present invention, the pressure-sensitive adhesive composition may contain an acrylic low molecular weight compound, a tackifier, an epoxy resin, a UV stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, One or more additives selected from the group consisting of an activator and a plasticizer.

According to one embodiment of the present invention, the solvent may be an organic solvent. The solvent may be an organic solvent for diluting a resin generally used in the art.

An embodiment of the present invention provides a pressure-sensitive adhesive layer comprising a cured product of the pressure-sensitive adhesive composition.

According to one embodiment of the present invention, the pressure-sensitive adhesive layer may be formed by coating the pressure-sensitive adhesive composition on a suitable processing substrate, followed by inducing a crosslinking reaction and curing the pressure-sensitive adhesive composition. Specifically, the pressure-sensitive adhesive layer may be prepared by thermosetting the pressure-sensitive adhesive composition. As a method of curing the pressure-sensitive adhesive composition to form the pressure-sensitive adhesive layer, a method known in the art can be used.

According to one embodiment of the present invention, the buildup peel force after the aging treatment of the pressure-sensitive adhesive layer may be 50% or more higher than the initial peel force before the aging treatment. Specifically, the buildup peel force after the aging treatment of the pressure-sensitive adhesive layer may be 90% or more, or 95% or more higher than the initial peel force before the aging treatment.

The initial peeling force was obtained by backing the pressure-sensitive adhesive layer on a polyethylene terephthalate (PET) film and then attaching the pressure-sensitive adhesive layer to an adherend using a 2 kg roller on a 1.1 T thick glass base material. , 7 bar) for 30 minutes, and then measured at ASTM D903 at a temperature of 25 ° C and a constant temperature and humidity of 180%.

The buildup peeling force was obtained by placing the pressure-sensitive adhesive layer on a polyethylene terephthalate (PET) film and then attaching it to a glass substrate of 1.1 T thickness using a 2 kg roller and leaving it in an autoclave (60 DEG C, 7 bar) for 30 minutes Means a value measured according to ASTM D903 at 180 DEG C under a constant temperature and humidity condition of 25 DEG C and 25 RH% after standing at 60 DEG C for 48 hours.

The pressure-sensitive adhesive layer according to an embodiment of the present invention has a property that the build-up peel force is increased by 95% or more as compared with the initial peel force, so that it can be easily removed when a failure occurs in the initial construction, . Further, the pressure-sensitive adhesive layer according to one embodiment of the present invention has a property that the build-up peel-off force increases by 95% or more as compared with the initial peel-off force, so that when the pressure-sensitive adhesive layer is applied to a display device or the like, .

An embodiment of the present invention provides a display device including the pressure-sensitive adhesive layer. Specifically, the type of the display device is not particularly limited and includes, for example, a plasma display panel (PDP), a liquid crystal display (LCD), an organic EL display, or a CRT.

According to an embodiment of the present invention, the display device may be a curved display device.

According to one embodiment of the present invention, the pressure-sensitive adhesive layer may be a frame and a display panel of the display device. The pressure-sensitive adhesive layer according to one embodiment of the present invention has excellent appearance characteristics, high temperature and high humidity durability, and high peeling force, so that the display panel and the frame of the display device can be effectively attached. Further, when the pressure-sensitive adhesive layer is applied to a curved surface display device, the adhesive force between the parts of the curved surface part is greatly improved, thereby preventing the floating phenomenon.

According to one embodiment of the present invention, there is provided a window deco film comprising the pressure-sensitive adhesive layer. The window deco film may be attached to a bezel area of a display device.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention is not construed as being limited to the embodiments described below. Embodiments of the present disclosure are provided to enable those skilled in the art to more fully understand the present invention.

[Example 1]

55 parts by weight of 2-ethylhexyl acrylate and 15 parts by weight of methacrylate as the alkyl group-containing (meth) acrylate monomer, 15 parts by weight of isobornyl acrylate as the cycloalkyl group-containing (meth) acrylate monomer, 5 parts by weight of acrylic acid as an acrylate monomer and 10 parts by weight of N-vinylpyrrolidone monomer were solution-polymerized to prepare a pressure-sensitive adhesive copolymer having a weight average molecular weight of 1,200,000 g / mol.

40 parts by weight of ethyl acetate as a solvent and 0.2 parts by weight of AIBN (2,2'-azo-bis-isobutyrylnitrile) as a thermal initiator were mixed with 100 parts by weight of the above-prepared viscous copolymer to prepare a pressure sensitive adhesive having a solid content of 22% A composition was prepared.

The pressure-sensitive adhesive composition prepared above was coated on a release PET substrate to a thickness of 25 탆 and cured at a temperature of 110 캜 for 5 minutes to obtain a pressure-sensitive adhesive layer.

The pressure-sensitive adhesive layers of Examples 2 to 4 and Comparative Examples 1 to 7 were prepared in the same manner as in Example 1, except that the composition in the production of the adhesive copolymer was changed as shown in Tables 1 and 2 below.

Example 1 Example 2 Example 3 Example 4 2-EHA 55 61.5 61 61 MA 15 15 15 15 IBoA 15 15 15 15 AA 5 8 7 7 NVP 10 0.5 2 2 Mw
(g / mol) 1,200,000 1,250,000 1,100,000 1,300,000 Viscosity
(@ Solid content 22%)
(cP) 2,000 2,100 1,100 2,250

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 2-EHA 50 61 61 57 61 64 68 MA 10 15 15 18 15 IBoA 10 15 15 18 15 CHMA 29 IBOMA 25 AA 10 7 7 7 7 7 7 NVP 20 2 2 DMAA 2 Mw
(g / mol) 1,500,000 1,500,000 1,000,000 1,520,000 1,300,000 660,000 610,000 Viscosity
@ Solid content 22%
(cP) 5,700 4,248 880 3,800 2,250 230 235

* 2-EHA: 2-ethylhexyl acrylate

* MA: methacrylate

* IBoA: isobornyl acrylate

* CHMA: cyclohexyl methacrylate

* IBoMA: isobornyl methacrylate

* AA: Acrylic acid

* NVP: N-vinylpyrrolidone

* DMAA: Dimethylamylamine

The evaluation results of the properties of the pressure-sensitive adhesive layer according to Examples 1 to 4 and Comparative Examples 1 to 7 are shown in Table 3 below.

Peel force
(kg / inch) High temperature / high humidity test
(85 DEG C / 85RH% / 24hrs) Exterior Initial peel force Buildup peel force Peel strength increase rate
(%) Glass substrate HC / PC substrate Example 1 3.3 6.5 96.97 OK OK OK Example 2 2.0 4.0 100 OK OK OK Example 3 2.0 4.3 115 OK OK OK Example 4 2.1 4.5 114.29 OK OK OK Comparative Example 1 Not measurable Not measurable - OK OK NG Comparative Example 2 2.6 4.2 61.54 OK OK NG Comparative Example 3 2.6 3.3 26.92 OK NG OK Comparative Example 4 3.1 3.8 22.58 OK OK NG Comparative Example 5 2.4 3.5 45.83 OK OK OK Comparative Example 6 Not measurable Not measurable - OK NG OK Comparative Example 7 Not measurable Not measurable - OK NG OK

The initial peel strength shown in Table 3 was obtained by attaching the produced pressure sensitive adhesive layer to a polyethylene terephthalate (PET) film and then attaching it to a glass substrate of 1.1 T thickness using a 2 kg roller and heating it in an autoclave Means the value measured according to ASTM D903 after leaving for 30 minutes and at a temperature of 25 ° C and a constant temperature and humidity of 25% RH and at a peel angle of 180 °.

The buildup peeling force shown in Table 3 was obtained by attaching the produced pressure-sensitive adhesive layer to a polyethylene terephthalate (PET) film and then attaching it to a glass substrate of 1.1 T thickness using a 2 kg roller, For 30 minutes, and further measured by ASTM D903 at 180 DEG C under a constant temperature and humidity condition of 25 DEG C and 25% RH after standing at 60 DEG C for 48 hours.

In the high-temperature / high-humidity test in Table 3, the pressure-sensitive adhesive layer prepared on a glass substrate or a polycarbonate substrate (Mitsubishi Rayon MRS58T) equipped with a hard coating layer was attached in a size of 7 cm x 13 cm, And allowed to stand for 24 hours. After left standing, whether bubbles were generated between the substrate and the pressure-sensitive adhesive layer and whether or not bubbles were generated were checked. When the bubbles were visually observed, NG was determined. When no bubbles were visually observed, evaluation was made as OK.

The external appearance characteristics shown in Table 3 are obtained by cutting the produced pressure-sensitive adhesive layer into A4 paper size, then irradiating a three-wavelength lamp, and detecting NG such as naked eye foreign matter, coating line, When it was not detected, it was evaluated as OK.

According to the results shown in Table 3, it can be seen that the pressure-sensitive adhesive layer according to Examples 1 to 4 satisfied excellent high-temperature and high-humidity durability and excellent external appearance characteristics. Further, the pressure-sensitive adhesive layer according to Examples 1 to 4 exhibits a build-up peel force of 50% or more with respect to the initial peel force, showing a good peel force increase rate.

In the pressure-sensitive adhesive layer of Comparative Example 1, the content of N-vinylpyrrolidone was too high, and the weight average molecular weight of the viscous copolymer was more than 1,300,000 g / mol, and the appearance characteristics were poor. In addition, the pressure-sensitive adhesive layer of Comparative Example 1 was too high in adhesive property to the substrate, and tearing occurred as the pressure-sensitive adhesive layer was broken during measurement of the peeling force, and measurement was impossible.

The pressure-sensitive adhesive layer according to Comparative Example 2 had a problem that the viscous copolymer had a weight-average molecular weight exceeding 1,300,000 g / mol and poor appearance characteristics.

The pressure-sensitive adhesive layer according to Comparative Example 3 had a problem that the weight average molecular weight of the viscous copolymer was too low and the rate of increase of the peeling force was low and the durability was high at high temperature and high humidity.

The pressure-sensitive adhesive layer according to Comparative Example 4 was produced in the same manner as in Comparative Example 4, except that N-vinylpyrrolidone was not used in the production of the viscous copolymer, the adhesive copolymer had a weight average molecular weight of more than 1,300,000 g / mol, Respectively.

In the pressure-sensitive adhesive layer of Comparative Example 5, dimethyl amyl amine was used instead of N-vinyl pyrrolidone in the production of the viscous copolymer, but the rate of increase of the peeling strength was low.

The pressure-sensitive adhesive layer according to Comparative Examples 6 and 7 had no problem in that N-vinylpyrrolidone was not used in the production of the viscous copolymer, and the weight average molecular weight of the pressure-sensitive adhesive copolymer was too low, resulting in extremely low peel strength and extremely high temperature and high humidity durability. In addition, the pressure-sensitive adhesive layer according to Comparative Examples 6 and 7 had too high a cohesive force of the pressure-sensitive adhesive layer itself, and stick-slip occurred in measuring the peeling force, and it was difficult to measure the peeling force.

Claims (11)

A sticky copolymer obtained by copolymerizing an alkyl group-containing (meth) acrylate monomer, a cycloalkyl group-containing (meth) acrylate monomer, a polar functional group-containing (meth) acrylate monomer and an N-vinyl pyrrolidone monomer; Curing agent; And a solvent,
And the weight average molecular weight of the viscous copolymer is 1,100,000 g / mol to 1,300,000 g / mol. The method according to claim 1,
Wherein the content of the N-vinylpyrrolidone monomer is 0.5 part by weight or more and 15 parts by weight or less based on 100 parts by weight of the total monomer forming the viscous copolymer. The method according to claim 1,
Wherein the content of the cycloalkyl group-containing (meth) acrylate monomer is 10 parts by weight or more and 30 parts by weight or less based on 100 parts by weight of the total monomer forming the viscous copolymer. The method according to claim 1,
Wherein the polar functional group-containing (meth) acrylate monomer comprises at least one of a hydroxy group-containing (meth) acrylate monomer and a carboxyl group-containing (meth) acrylate monomer. The method according to claim 1,
Wherein the content of the polar functional group-containing (meth) acrylate monomer is 3 parts by weight or more and 20 parts by weight or less based on 100 parts by weight of the total monomers forming the adhesive copolymer. The method according to claim 1,
Wherein the alkyl group-containing (meth) acrylate monomer comprises (meth) acrylate having methacrylate and an alkyl group having 2 to 20 carbon atoms. The method according to claim 1,
Wherein the viscosity of the pressure-sensitive adhesive composition at a solid content of 22% is 2,500 cP or less. The method according to claim 1,
Wherein the curing agent is a thermosetting agent. A pressure-sensitive adhesive layer comprising a cured product of the pressure-sensitive adhesive composition according to claim 1. The method of claim 9,
Wherein the build-up peel force after the aging treatment of the pressure-sensitive adhesive layer is increased by 50% or more as compared with the initial peel force before the aging treatment. A display device comprising a pressure-sensitive adhesive layer according to claim 9.