KR20250111420A - Adhesive film, optical member comprising the same and optical display apparatus comprising the same - Google Patents

Abstract

An adhesive film comprising a cured product of a composition for an adhesive film comprising a polymer of a (meth)acrylic monomer mixture, wherein the adhesive film has a peel strength of 400 gf/25 mm or more with respect to a polyethylene terephthalate film having an antistatic layer, when the adhesive film is laminated on a specimen thereof and left at 60° C. and 93% relative humidity for 500 hours, and the adhesive film has a storage modulus of 10 to 100 kPa at 25° C., and the adhesive film has a resistance change rate of Equation 1 of 1% or less, an optical member comprising the same, and an optical display device comprising the same are provided.

Description

{ADHESIVE FILM, OPTICAL MEMBER COMPRISING THE SAME AND OPTICAL DISPLAY APPARATUS COMPRISING THE SAME}

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

As interest in foldable optical displays increases, adhesive films included in optical displays are also required to have excellent foldable properties. As the usage environments of foldable optical displays, especially foldable phones, become more diverse, foldable phones can also be used in underwater environments. In order to use foldable phones underwater, waterproofing is essential.

A method of applying a barrier layer or barrier film capable of preventing moisture penetration to a foldable optical display device may be considered. However, since the conventional barrier layer or barrier film has a high modulus, such a barrier layer or barrier film may be subject to stress when folded. Therefore, it may be desirable to use an adhesive film that can provide both excellent foldability and a waterproof function. For the waterproof function, high peeling strength after long-term storage at high temperature and high humidity and low resistance change rate after long-term storage at high temperature and high humidity are required.

The background technology of the present invention is disclosed in Japanese Patent Publication No. 2013-072951, etc.

Provides an adhesive film that provides excellent folding properties, high peel strength after long-term storage at high temperature and high humidity, and low resistance change rate after long-term storage at high temperature and high humidity.

Provides an adhesive film that provides excellent waterproof properties.

Provides an adhesive film with high adhesion to an adherend.

According to one embodiment, the adhesive film comprises a cured product of a composition for an adhesive film comprising a polymer of a (meth)acrylic monomer mixture, wherein the adhesive film has a peel strength of 400 gf/25 mm or more with respect to a polyethylene terephthalate film having an antistatic layer, measured after leaving a specimen on which the adhesive film is laminated at 60° C. and 93% relative humidity for 500 hours, and the adhesive film has a storage modulus of 10 to 100 kPa at 25° C., and the adhesive film has a resistance change rate of 1% or less in the following Equation 1:

[Formula 1]

Resistance change rate = │ (R2 - R1)/R1 │ x 100

(In the above equation 1,

R1 is an indium tin oxide film; a first silver layer and a second silver layer each laminated on both ends of an upper surface of the indium tin oxide film; an adhesive film covering the indium tin oxide film, a part of the first silver layer, a part of the second silver layer, and a part of the first silver layer between the first silver layer and the second silver layer; and a release film covering the adhesive film; the line resistance (unit: Ω) measured between the first silver layer and the second silver layer for a specimen having the same.

R2 is the line resistance (unit: Ω) measured between the first silver layer and the second silver layer after the specimen was left at 60°C and 95% relative humidity for 500 hours.

According to one embodiment, the optical display device includes the adhesive film.

An adhesive film was provided which provided excellent folding properties, high peel strength after long-term storage at high temperature and high humidity, and low resistance change rate after long-term storage at high temperature and high humidity.

We provide an adhesive film that provides excellent waterproof properties.

Provided is an adhesive film having high adhesion to an adherend.

Figure 1 is a cross-sectional view of a specimen for measuring wire resistance.
Figure 2 is a plan view of a specimen for measuring line resistance.

Hereinafter, embodiments of the present application will be described in more detail. However, the technology disclosed in the present application is not limited to the embodiments described herein and may be embodied in other forms. However, the embodiments introduced herein are provided so that the disclosed content can be thorough and complete and so that the idea of the present application can be sufficiently conveyed to those skilled in the art.

The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

In this specification, the "glass transition temperature of a homopolymer" may mean a glass transition temperature (Tg) measured using a DSC Discovery from TA Instrument for a homopolymer of a target monomer. Specifically, for a homopolymer of a target monomer, the temperature is increased to 180°C at a heating rate of 20°C/min, slowly cooled to -100°C, and then increased to 100°C at a heating rate of 10°C/min. After obtaining data on an endothermic transition curve, the inflection point of the endothermic transition curve may be determined as the glass transition temperature.

As used herein, “(meth)acrylic” means acrylic and/or methacrylic.

In this specification, “weight average molecular weight” can be a value obtained by polystyrene conversion in gel permeation chromatography.

When describing a numerical range in this specification, “X to Y” means X or more and Y or less (X≤ and ≤Y).

According to one embodiment, an adhesive film is provided which provides excellent foldability, high peel strength after long-term storage at high temperature and high humidity, and low resistance change rate after long-term storage at high temperature and high humidity. According to one embodiment, an adhesive film with high adhesion to an adherend is provided. The adhesive film can be used in an optical display device which requires excellent waterproof function while providing excellent foldability.

According to one embodiment, the adhesive film has a peel strength of 400 gf/25 mm or more with respect to a polyethylene terephthalate film having an antistatic layer, as measured after leaving a specimen on which the adhesive film is laminated on a polyethylene terephthalate film having an antistatic layer at 60° C. and 95% relative humidity for 500 hours. In the above range, an optical display device having the adhesive film has an excellent waterproof function, thereby expanding the range of applications of the adhesive film and the optical display device. For example, the peel strength can be 400 to 1000 gf/25 mm, or 400 to 800 gf/25 mm.

Here, the 'anti-static layer' may be a coating layer manufactured by a conventional method known to those skilled in the art. For example, the anti-static layer may include, but is not limited to, an ionic liquid, a conductive polymer, etc.

The adhesive film has a storage modulus of 10 to 100 kPa at 25°C. In this range, the foldability of an optical display device having the adhesive film can be excellent. For example, the storage modulus can be 11 to 90 kPa.

The adhesive film has a resistance change rate of 1% or less in the following formula 1: Within the resistance change rate range, an optical display device having the adhesive film can be operated without malfunction even after long-term exposure to high temperature and high humidity, so that the waterproof function can be excellent. For example, the resistance change rate can be 0 to 1%:

[Formula 1]

Resistance change rate = │ (R2 - R1)/R1 │ x 100

(In the above equation 1,

R1 is an indium tin oxide film; a first silver layer and a second silver layer each laminated on both ends of an upper surface of the indium tin oxide film; an adhesive film covering the indium tin oxide film, a part of the first silver layer, a part of the second silver layer, and a part of the first silver layer between the first silver layer and the second silver layer; and a release film covering the adhesive film; the line resistance (unit: Ω) measured between the first silver layer and the second silver layer for a specimen having the same.

R2 is the line resistance (unit: Ω) measured between the first silver layer and the second silver layer after the specimen was left at 60°C and 9３% relative humidity for 500 hours.

According to one embodiment, the adhesive film is laminated on a polyethylene terephthalate film having an antistatic layer, and a peeling force of the adhesive film relative to the polyethylene terephthalate film having an antistatic layer, as measured after leaving the adhesive film on the polyethylene terephthalate film having an antistatic layer for 30 minutes at 25° C., may be 600 gf/25 mm or more, for example, 600 to 1,000 gf/25 mm.

According to one embodiment, the adhesive film may have a substrate adhesion of 400 gf/25 mm or more. In the above range, the adhesive film may be adhered to an adherend in a short period of time, thereby increasing reliability. For example, the substrate adhesion may be 400 to 800 gf/25 mm. Here, the 'substrate adhesion' refers to the adhesion to PET used for the barrier film.

The above adhesive film is a photocurable transparent adhesive (OCA) and can be used in a foldable optical display device.

The adhesive film may have a thickness of 100 μm or less. In the above range, the adhesive film may provide a thin thickness so as to sufficiently provide a thinning effect even when used in a foldable optical display device. Specifically, the adhesive film may have a thickness of more than 0 μm and less than or equal to 100 μm, or from 10 μm to 80 μm.

The adhesive film may have a storage modulus of 200 kPa or less at -20°C, for example, 0.1 to 200 kPa, or 50 to 200 kPa. In this range, it may help provide excellent foldable properties under a wide range of conditions.

The adhesive film may have a storage modulus of 200 kPa or less at 60°C, for example, 1 to 200 kPa, 10 to 100 kPa. In this range, it may help to provide excellent foldable properties under a wide range of conditions.

The adhesive film may have a storage modulus ratio of -20°C storage modulus: 60°C storage modulus of 1:0.1 to 1:0.8, specifically 1:0.2 to 1:0.5. In the above range, it may be easy to provide excellent foldable properties under a wide range of conditions.

The adhesive film may have a haze of 1% or less, for example, 0% to 1%, in the visible light range, for example, at a wavelength of 380 to 780 nm. In this range, the adhesive film may be used in an optical display device.

The above adhesive film is a (meth)acrylic adhesive film, and in one specific example, may be a pressure sensitive adhesive (PSA).

The above adhesive film comprises a cured product of a composition for an adhesive film comprising a polymer of a (meth)acrylic monomer mixture. Specifically, the composition for an adhesive film comprises a polymer of the (meth)acrylic monomer mixture, a (meth)acrylate having a carboxylic acid group, a photoinitiator, and a crosslinking agent having an alkylene oxide group and a (meth)acrylate group. A composition comprising a (meth)acrylate having a carboxylic acid group; and a crosslinking agent having an alkylene oxide group and a (meth)acrylate group can easily provide the effects described above.

In one specific embodiment, the adhesive film may include a photocurable product of the composition for the adhesive film.

The polymer of the above (meth)acrylic monomer mixture can easily form a matrix of an adhesive film and provide the above-described peel strength and resistance change rate.

The above monomer mixture may include a (meth)acrylic monomer having an alkyl group and a (meth)acrylic monomer having a hydroxyl group. In one specific example, the total amount of the (meth)acrylic monomer having an alkyl group and the (meth)acrylic monomer having a hydroxyl group may be comprised in the monomer mixture at least 95 wt%, for example, 99 to 100 wt%, such as 100 wt%. In the above range, it may be easy to provide the above-described effect of the present invention.

The (meth)acrylic monomer having an alkyl group can be selected from among (meth)acrylic monomers having an unsubstituted alkyl group of a straight or branched chain having 1 to 20 carbon atoms. A (meth)acrylic monomer having a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms is a (meth)acrylic acid ester having an unsubstituted straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms in the ester moiety, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, iso-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, iso-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate. It can contain more than one type.

According to one embodiment, the (meth)acrylic monomer having the alkyl group may be included in the monomer mixture at 60 wt% or more, specifically 60 to 90 wt%, and more specifically 70 to 85 wt%. In the above range, it may be easy to form a matrix of an adhesive film.

According to one embodiment, the (meth)acrylic monomer having an alkyl group may include a (meth)acrylic monomer having a glass transition temperature of the homopolymer of -50°C or lower. The (meth)acrylic monomer having a glass transition temperature of the homopolymer of -50°C or lower may facilitate reaching the storage modulus and peel strength described above by lowering the glass transition temperature of the polymer. The (meth)acrylic monomer may have a glass transition temperature of the homopolymer of specifically -80°C to -50°C. The 'glass transition temperature of the homopolymer of the (meth)acrylic monomer' may be measured by a conventional method known to those skilled in the art or may be obtained by referring to a commercial catalog.

In one specific example, the (meth)acrylic monomer having an alkyl group and a glass transition temperature of the homopolymer of -50° C. or lower may be included in the monomer mixture at 60 wt% or more, specifically 60 to 90 wt%, and more specifically 70 to 85 wt%. In the above range, it may be easy to lower the glass transition temperature of the polymer.

A (meth)acrylic monomer having a glass transition temperature of -50°C or lower of the homopolymer may be contained as one or more types, for example, two or more types, in the monomer mixture.

The (meth)acrylic monomer having the above hydroxyl group can be selected and used from among (meth)acrylic monomers having a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms and having one or more hydroxyl groups. For example, a (meth)acrylic monomer having a hydroxyl group is a (meth)acrylic acid ester having an alkyl group having 1 to 20 carbon atoms and having one or more hydroxyl groups in the ester moiety, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1,4-cyclohexanedimethanol mono (meth)acrylate, 1-chloro-2-hydroxypropyl (meth)acrylate, diethylene glycol mono (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, 4-hydroxycyclopentyl (meth)acrylate, It may contain at least one type of 4-hydroxycyclohexyl (meth)acrylate.

According to one embodiment, the (meth)acrylic monomer having the hydroxyl group may be included in the monomer mixture at 40 wt% or less, specifically 10 to 40 wt%, and more specifically 15 to 30 wt%. In the above range, it may be easy to obtain the above-described peel strength and storage modulus.

According to one embodiment, the monomer mixture may not include a (meth)acrylic monomer having a carboxylic acid group. That is, the content of the (meth)acrylic monomer having a carboxylic acid group in the monomer mixture may be 0 wt%. An adhesive film formed with a composition including a polymer of a monomer mixture including the (meth)acrylic monomer mixture having a carboxylic acid group may have an increased storage modulus at a temperature such as 25° C. For example, the (meth)acrylic monomer having a carboxylic acid group may be a (meth)acrylate having a carboxylic acid group described below.

The above polymer may have a glass transition temperature of -50°C or lower, for example, -70°C to -50°C. In the above range, it may be easy to reach the above storage modulus and peel strength.

The above polymer may have a weight average molecular weight of 800,000 g/mol or more, for example, 800,000 to 1.5 million g/mol, or 1 million to 1.3 million g/mol. In the above range, it may be easy to reach the above storage modulus and peel strength.

The above polymer can be prepared by polymerizing, for example, photopolymerizing, the above monomer mixture. In one specific embodiment, the polymer can be a partially polymerized product or a fully polymerized product of the monomer mixture. The partially polymerized product can be a product in which the monomer mixture is not fully polymerized with a degree of polymerization of 100% but is polymerized less than 100%, and can be a mixture of a (meth)acrylic polymer formed from the monomer mixture and unreacted (meth)acrylic monomers that remain. The fully polymerized product can be a product in which the monomer mixture is fully polymerized with a degree of polymerization of 100% and contains only a (meth)acrylic copolymer.

The above polymer can be prepared by polymerizing the above monomer mixture using a polymerization method. The polymerization can be performed by a conventional method known to those skilled in the art. For example, it can be performed by adding a predetermined amount of a photoinitiator to the above monomer mixture and irradiating it with light.

The crosslinking agent having the above alkylene oxide group and (meth)acrylate group may be a crosslinking agent having an alkylene oxide group of *-(-R-O-)-* (* is a linking moiety, and R is a substituted or unsubstituted alkylene group having 2 to 5 carbon atoms).

The crosslinking agent having the above-mentioned alkylene oxide group and (meth)acrylate group can help to secure the above-mentioned peeling strength and reduce the resistance change rate even after the adhesive film is left at high temperature and high humidity for a long period of time by being included together with the (meth)acrylate having a carboxylic acid group described below.

The above-mentioned alkylene oxide group having 2 to 5 carbon atoms may be an ethylene oxide group or a propylene oxide group, but is preferably an ethylene oxide group. Through this, an adhesive film can be formed through a crosslinking reaction with the polymer, and foldability can be improved.

The crosslinking agent having the above alkylene oxide group and (meth)acrylate group may contain 2 to 6, preferably 3 to 5, (meth)acrylate groups which are photocurable functional groups.

The crosslinking agent having the above alkylene oxide group and (meth)acrylate group can be used as a commercially available product.

The crosslinking agent having the above alkylene oxide group and (meth)acrylate group may be included in an amount of 0.01 to 0.5 parts by weight, for example, 0.05 to 0.3 parts by weight, or 0.05 to 0.2 parts by weight, based on 100 parts by weight of the polymer. In the above range, it is easy to increase the peeling strength at high temperature and high humidity and reduce the resistance change rate while preventing an excessive increase in the storage modulus of the adhesive film.

The (meth)acrylate having the carboxylic acid group is not included in the monomer mixture, but is included in the composition for the adhesive film. When the (meth)acrylate having the carboxylic acid group is included in the monomer mixture and is present in the polymer, the storage modulus of the adhesive film can be increased.

The (meth)acrylate having the above carboxylic acid group can self-cure or cure together with the alkylene oxide group and the (meth)acrylate group during photocuring of the composition for an adhesive film including a crosslinking agent having the above alkylene oxide group and the (meth)acrylate group, thereby providing high cohesion and securing resistance to moisture permeation, thereby increasing the peeling strength and reducing the resistance change rate when the adhesive film is left at high temperature and high humidity for a long period of time.

The (meth)acrylate having the above carboxylic acid group may include carboxylalkyl (meth)acrylates, such as beta-carboxylethyl (meth)acrylate, etc. In this case, the 'alkyl' may be an alkyl group having 1 to 5 carbon atoms.

The (meth)acrylate having the above carboxylic acid group may be included in an amount of 0.1 to 5 parts by weight, for example, 1 to 5 parts by weight, based on 100 parts by weight of the above polymer. In the above range, when the adhesive film is left at high temperature and high humidity for a long period of time, the peeling strength may be high and the resistance change rate may be low.

The photoinitiator can photocure the composition for an adhesive film to form an adhesive film or, if the polymer is a partial polymer, completely polymerize the remaining (meth)acrylic monomer.

Any photoinitiator that can induce a polymerization reaction or curing reaction by generating radicals during a photocuring process such as by light irradiation can be used. For example, the photoinitiator may be a photoradical initiator, such as a benzoin-based, hydroxy ketone-based, amino ketone-based or phosphine oxide-based photoinitiator, and specifically, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, 2,2-dimethoxy-2-phenylacetophenone, 2,2'-diethoxy acetophenone, 2,2'-dibuoxy acetophenone, 2-hydroxy-2-methyl propiophenone, p-t-butyl trichloro acetophenone, p-t-butyl dichloro acetophenone, 4-chloro acetophenone, 2,2'-dichloro-4-phenoxy acetophenone, and other acetophenone compounds, dimethyl anino Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholino phenyl)-butan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4nonoxidiethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, Examples thereof include 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylamino benzoic acid ester, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone], and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide.

The photoinitiator may be included in an amount of 0.0001 to 5 parts by weight, specifically 0.001 to 3 parts by weight, or 0.001 to 1 part by weight, based on 100 parts by weight of the polymer. In the above range, the curing reaction can proceed completely, the residual amount of photoinitiator can be prevented from remaining and lowering the light transmittance of the adhesive film, and also the occurrence of bubbles can be reduced and excellent reactivity can be achieved.

The composition for the above adhesive film, i.e. the adhesive film, may further contain a silane coupling agent.

The silane coupling agent can further increase the peel strength of the adhesive film. The silane coupling agent can include a conventional silane coupling agent known to those skilled in the art. For example, the silane coupling agent can include, but is not limited to, an epoxy group-containing silane coupling agent such as glycidoxypropyltrimethoxysilane and glycidoxypropylmethyldimethoxysilane.

The above silane coupling agent may be included in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the polymer. In the above range, the peeling strength may be improved.

According to one embodiment, the composition for the adhesive film may be a solvent-free type that does not contain a solvent.

According to another embodiment, the composition for the adhesive film may further include a solvent. The solvent can make the surface of the adhesive film uniform when forming a thin adhesive film, particularly a thickness of 20 ㎛ or less, from the composition. The solvent may be any common solvent known to those skilled in the art without limitation. For example, the solvent may be an organic solvent such as ethyl acetate, methyl ethyl ketone, or methyl isobutyl ketone, but is not limited thereto. The composition may have a solid content of 50 wt% or less, for example, 20 wt% or less.

The composition for the adhesive film, i.e., the adhesive film, may further include an additive. The additive may provide additional functions to the adhesive film. Specifically, the additive may include at least one of a UV absorber, a reaction inhibitor, an adhesion improver, a thixotropic agent, a conductivity agent, a pigment regulator, a stabilizer, an antioxidant, a leveling agent, and an antistatic agent, but is not limited thereto. The content of the additive in the composition, i.e., the adhesive film, may be appropriately selected within a range that does not affect the effects of the present invention.

According to one embodiment, the adhesive film may not contain organic nanoparticles. Here, the 'organic nanoparticles' may be organic nanoparticles known to provide foldability, for example, core-shell nanoparticles. The adhesive film may provide excellent foldability even if it does not contain organic nanoparticles.

According to another embodiment, the adhesive film may further comprise the organic nanoparticles.

The adhesive film can be formed of the adhesive film composition described above. Specifically, the adhesive film can be manufactured by applying the adhesive film composition to a release film and then photocuring it. The photocuring can include irradiation with a low-pressure lamp at a wavelength of 300 nm to 400 nm in an oxygen-free environment and an irradiation dose of 400 mJ/cm ² to 3000 mJ/cm ² , but the irradiation dose and irradiation wavelength can be changed depending on the thickness of the adhesive film and the irradiation conditions.

Hereinafter, an optical member of one embodiment of the present invention will be described.

The optical member includes an optical film and an adhesive film formed on at least one surface of the optical film, and the adhesive film includes an adhesive film according to an embodiment of the present invention. Accordingly, the optical member has good bending and/or good folding characteristics and can be used in a foldable display device.

In one embodiment, the optical film provides a certain optical function of the display device, such as polarization, optical compensation, display quality improvement, and/or conductivity, and the optical film may be a window film, a window, a polarizing plate, a color filter, a phase difference film, an elliptically polarizing film, a reflective polarizing film, an antireflection film, a compensation film, a brightness enhancement film, an alignment film, a light diffusion film, a glass scattering prevention film, a surface protection film, an OLED device barrier layer, a plastic LCD substrate, a transparent electrode film including ITO (indium tin oxide), FTO (fluorinated tin oxide), AZO (aluminum dopped zinc oxide), CNT (carbon nanotube), Ag nanowire, graphene, and the like. A method for manufacturing the optical film can be easily manufactured by a person skilled in the art to which the present invention pertains.

For example, a touch panel can be formed by attaching an adhesive film to a window or optical film using a touchpad. Or, as in the past, it can be applied as an adhesive film to a conventional polarizing film.

In another embodiment, the optical film is an optically transparent optical film, and the optical member including the optical film and the adhesive film can function as a support layer of the display element. For example, the display element can include a window film, etc. The window film can include the optical member and a window coating layer (e.g., a silicone-based coating layer) formed on the optical member. Specifically, the optical film can be a film formed of one or more resins from a cellulose resin including triacetyl cellulose or the like, a polyester resin including polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, etc., a polycarbonate resin, a polyimide resin, a polystyrene resin, a polyacrylate resin including polymethyl methacrylate, a cyclic olefin polymer resin, an acrylic resin, and a polyamide resin having a total light transmittance of 90% or more in a visible light region. The optical film may have a thickness of 10 ㎛ to 100 ㎛, specifically 20 ㎛ to 75 ㎛, and more specifically 30 ㎛ to 50 ㎛. It may be used as a support layer of a display device within the above range.

The optical member may be a two-layer optical member formed with an optical film and an adhesive film formed on one surface of the optical film. Alternatively, the optical member may be a three-layer or more film laminate comprising two or more optical films, at least two of which are laminated by the adhesive film of the present invention.

The optical display device of the present invention includes the adhesive film of the present invention.

The optical display device may include a light-emitting element display device including an organic light-emitting element display device, a liquid crystal display device, etc. The optical display device may include a flexible display device. However, the optical display device may also include a non-flexible display device.

Hereinafter, the configuration and operation of the present invention will be described in more detail through examples of the present invention. However, the following examples are intended to help understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Example 1

100 parts by weight of a monomer mixture containing 80 parts by weight of 2-ethylhexyl acrylate (2-EHA) and 20 parts by weight of 4-hydroxybutyl acrylate (4-HBA) and 0.05 parts by weight of Irgacure 651 (2,2-dimethoxy-2-phenylacetophenone, BASF) as an initiator were well mixed in a reactor. After the dissolved oxygen in the reactor was exchanged with nitrogen gas, the mixture was partially polymerized by irradiating the mixture with ultraviolet rays using a low-pressure mercury lamp, thereby producing a polymer (viscous liquid having a viscosity of 5,000 cps at 25°C).

To the above viscous liquid, based on 100 parts by weight of the solid content of the polymer, 0.3 parts by weight of Irgacure 127, 0.1 parts by weight of Irgacure 651, 0.1 parts by weight of a crosslinking agent MF-001 having an alkylene oxide group and a (meth)acrylate group, and 0.5 parts by weight of beta-carboxyethyl acrylate were added and mixed to prepare a composition for an adhesive film.

The composition for the manufactured adhesive film was applied to a first release type PET (polyethylene terephthalate) film, which is a release film, and covered with a second release type PET film, and then irradiated with ultraviolet rays at a light dose of 2000 mJ/cm ² to manufacture an adhesive sheet of the first release type PET film - an adhesive film having a thickness of 50 ㎛ - a second release type PET film.

Examples 2 to 5

In Example 1, an adhesive film was manufactured in the same manner as in Example 1, except that the content of beta-carboxyethyl acrylate, the content of the crosslinking agent having an alkylene oxide group and a (meth)acrylate group were changed as shown in Table 1 below. In Table 1 below, the unit is parts by weight, and '-' means that the corresponding component is not included.

Comparative examples 1 and 2

In Example 1, the content of beta-carboxyethyl acrylate, the content of the crosslinking agent having an alkylene oxide group and a (meth)acrylate group were changed as shown in Table 1 below, and an adhesive film was manufactured in the same manner as in Example 1, except that the content of each component in the composition for the adhesive film was changed. In Table 1 below, the unit is parts by weight, and '-' means that the corresponding component is not included.

The compositions of the adhesive films of the examples and comparative examples are shown in Table 1 below. The physical properties of the adhesive films of the examples and comparative examples were evaluated in Table 1 below.

(1) Initial peel strength: After peeling one of the release PET films from among the adhesive sheets manufactured in the examples and comparative examples, a polyurethane film (thickness: 25 μm, NK Company) was laminated to the peeled surface, cut to a size of width x length (2.5 cm x 10 cm), and the remaining release PET film was peeled off, and then adhered to a polyethylene terephthalate film (TAK) having an antistatic layer, thereby manufacturing a specimen laminated in the order of polyethylene terephthalate film having an antistatic layer - adhesive film - polyurethane film. After manufacturing the specimen and leaving it at 25°C for 30 minutes, the specimen was fixed to a TA (Texture Analyzer) Instrument for measuring peel strength, and the peel strength was measured when peeling an adhesive film and a polyurethane film laminate from a polyethylene terephthalate film having an antistatic layer at 25°C at a peel speed of 300 mm/min and a peel angle of 180°.

(2) High temperature and high humidity peel strength: The specimens were prepared in the same manner as in (1). The prepared specimens were left at 60℃ and 95% relative humidity for 500 hours. Then, the peel strength was measured in the same manner as in (1).

(3) Resistance change rate: From the adhesive sheets manufactured in the examples and comparative examples, the release films on both sides were removed to obtain an adhesive film, and the obtained adhesive film, indium tin oxide film, silver paste (including silver powder for forming a silver layer), and release PET film were used to manufacture specimens for measuring resistance in Figs. 1 and 2.

Referring to FIGS. 1 and 2, an indium tin oxide film (2) is bonded to a glass plate (1) with an adhesive, the indium tin oxide film (2) (thickness: 150 μm); a first silver layer (3) and a second silver layer (4) laminated respectively on both ends of the upper surface of the indium tin oxide film (2); an adhesive film (5) (thickness: 150 μm) covering a portion of the first silver layer (3), a portion of the second silver layer (4), and the indium tin oxide film (2) positioned between the first silver layer and the second silver layer; For a specimen having a release PET film (6) (thickness: 50 ㎛) covering the adhesive film (5), the line resistance (unit: Ω, R1) between the first silver layer (3) and the second silver layer (4) and between measurement points (A) and (B) was measured using a resistance meter (7) (3244-60, Hioki).

After the above specimen was left at 60℃ and 9３% relative humidity for 500 hours, the line resistance (unit: Ω, R2) measured between the first silver layer and the second silver layer was measured using the same method as above.

The resistance change rate was measured using the measured R1 and R2 and the above equation 1.

(4) Adhesion to substrate: A specimen having a laminated structure of the polyurethane film/adhesive film/polyethylene terephthalate film with an antistatic layer described above was manufactured, and the peeling force was measured when the adhesive film was peeled from the polyethylene terephthalate film with an antistatic layer. The peeling force was measured at a peeling speed of 50 mm/min at 25°C with a T-Peel structure.

(5) Storage modulus: The storage modulus was measured under auto strain conditions at a shear rate of 1 rad/sec and strain of 1% using a rheometer (TA ARES G2), a dynamic viscoelasticity measuring device. The adhesive films manufactured in the examples and comparative examples were laminated in multiple layers to produce samples with a thickness of 800 ㎛. The laminates were perforated with a hole puncher having a diameter of 8 mm to use as specimens. A force of 1.0 N of normal force was applied to the specimen using an 8 mm jig, and the temperature was increased at a temperature of 5°C/min from -60°C to 90°C for measurement, and the storage modulus was obtained at 25°C.

(6) Foldability: In the adhesive sheets manufactured in the examples and comparative examples, the release films on both sides were separated to obtain an adhesive film. The adhesive film was placed between two 50 ㎛ thick polyethylene terephthalate (PET) films that had been corona-treated, and the corona-treated side of the PET film was made to come into contact with the adhesive film and attached with a roller, and then aged at room temperature for 12 hours and cut to a size of width X length (70 mm X 140 mm) to manufacture a specimen. The cut specimen was fixed to a bendability evaluation device (CFT-200, Covotech) using an adhesive (4965, Tesa Co.), and bending (one cycle is defined as bending the adhesive film in half once and unfolding it) at a speed of 30 cycles per minute was repeated at 25°C so that the radius of curvature of the length (140 mm) of the specimen became 3 mm. When bending was repeated as 1 cycle, the initial number of cycles at which cracks occurred visually in the polyethylene terephthalate film was measured. An adhesive film with a large minimum number of cycles means an adhesive film that can easily relax the stress of the polyethylene terephthalate film caused by bending. If the initial number of cycles is 100,000 or more, it is OK, and if it is less than 100,000, it is NG.

Example Comparative example 1 2 3 4 5 1 2 Monomer mixture 2-EHA 80 80 80 80 80 80 80 4-HBA 20 20 20 20 20 0 20 2-HEA 0 0 0 0 0 20 0 Beta-CEA 0 0 0 0 0 0 0 Composition IC127 0.3 0.3 0.3 0.3 0.3 0.3 0.3 IC651 0.1 0.1 0.1 0.1 0.1 0.1 0.1 MF-001 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Beta-CEA 0.5 1 2 3 5 0 0 AA 0 0 0 0 0 0 3 ACMO 0 0 0 0 0 5 0 Initial peel strength (gf/25mm) 750 790 795 800 807 930 850 Peel strength after high temperature and high humidity (gf/25mm) 450 465 480 491 494 340 630 Resistance change rate (%) 0 0 0 0 0 0 3 Adhesion of substrate (gf/25mm) 410 430 440 444 450 380 470 Storage modulus (kPa) 31 34 35 37 39 47 48 Foldability OK OK OK OK OK OK OK

*In Table 1 above,

AA: Acrylic acid

2-HEA: 2-Hydroxyethyl acrylate

ACMO: Acryloylmorpholine.

As shown in Table 1 above, the adhesive film of the example provided the effects of excellent foldability, high peel strength after long-term storage at high temperature and high humidity, and low resistance change rate after long-term storage at high temperature and high humidity.

On the other hand, the adhesive film of the comparative example did not provide all the effects described above.

Simple modifications or changes of the present invention can be easily implemented by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (15)

As an adhesive film,
The above adhesive film comprises a cured product of a composition for an adhesive film comprising a polymer of a (meth)acrylic monomer mixture,
The adhesive film has a peel strength of 400 gf/25 mm or more for the polyethylene terephthalate film having the antistatic layer, measured after leaving the specimen on which the adhesive film is laminated on the polyethylene terephthalate film having the antistatic layer at 60° C. and 93% relative humidity for 500 hours.
The above adhesive film has a storage modulus of 10 to 100 kPa at 25°C,
The above adhesive film is an adhesive film having a resistance change rate of 1% or less in the following formula 1:
[Formula 1]
Resistance change rate = │ (R2 - R1)/R1 │ x 100
(In the above equation 1,
R1 is an indium tin oxide film; a first silver layer and a second silver layer each laminated on both ends of an upper surface of the indium tin oxide film; an adhesive film covering the indium tin oxide film, a part of the first silver layer, a part of the second silver layer, and a part of the first silver layer between the first silver layer and the second silver layer; and a release film covering the adhesive film; the line resistance (unit: Ω) measured between the first silver layer and the second silver layer for a specimen having the same.
R2 is the line resistance (unit: Ω) measured between the first silver layer and the second silver layer after the specimen was left at 60°C and 95% relative humidity for 500 hours.
In the first paragraph, the adhesive film is an adhesive film in which a specimen is prepared by laminating the adhesive film on a polyethylene terephthalate film having an antistatic layer, and the adhesive film has a peeling force of 600 gf/25 mm or more for the polyethylene terephthalate film having an antistatic layer, measured after leaving the specimen at 25° C. for 30 minutes.
In the first aspect, the composition for the adhesive film comprises a polymer of the (meth)acrylic monomer mixture, a (meth)acrylate having a carboxylic acid group, a photoinitiator, and a crosslinking agent having an alkylene oxide group and a (meth)acrylate group.
An adhesive film in claim 3, wherein the (meth)acrylate having a carboxylic acid group is a beta-carboxylalkyl (meth)acrylate.
An adhesive film in claim 3, wherein the alkylene oxide group is an ethylene oxide group or a propylene oxide group.
An adhesive film in claim 3, wherein the crosslinking agent having an alkylene oxide group and a (meth)acrylate group has 2 to 6 (meth)acrylate groups.
An adhesive film in claim 1, wherein the monomer mixture includes a (meth)acrylic monomer having an alkyl group and a (meth)acrylic monomer having a hydroxyl group.
An adhesive film in claim 7, wherein the total amount of the (meth)acrylic monomer having the alkyl group and the (meth)acrylic monomer having the hydroxyl group is comprised at 95 wt% or more of the monomer mixture.
An adhesive film in claim 7, wherein the (meth)acrylic monomer having the alkyl group in the monomer mixture is contained in an amount of 60 to 90 wt% and the (meth)acrylic monomer having the hydroxyl group is contained in an amount of 10 to 40 wt%.
An adhesive film in claim 1, wherein the monomer mixture does not contain a (meth)acrylic monomer having a carboxylic acid group.
In the third paragraph, the composition for the adhesive film
100 parts by weight of a polymer of the above (meth)acrylic monomer mixture,
0.1 to 5 parts by weight of (meth)acrylate having the above carboxylic acid group,
0.001 to 5 parts by weight of the above photoinitiator, and
An adhesive film comprising 0.01 to 0.5 parts by weight of a crosslinking agent having an alkylene oxide group and a (meth)acrylate group.
In the first paragraph, the adhesive film does not contain organic nanoparticles.
In the first paragraph, the adhesive film has a substrate adhesion of 400 gf/25 mm or more.
An optical member comprising an adhesive film according to any one of claims 1 to 13.
An optical display device comprising an adhesive film according to any one of claims 1 to 13.