KR20200078019A - Adhesive film having variable adhesion and display device comprising the same - Google Patents

Abstract

The present invention relates to an adhesive film having a variable adhesive force and a display device comprising the same. More specifically, the present invention relates to the adhesive film having the variable adhesive force including an adhesive layer whose adhesive force changes according to presence or absence of UV irradiation, and the display device comprising the same. The adhesive film having the variable adhesive force includes: a base substrate; an adhesive layer; and a release film.

Description

Adhesive film with variable adhesive force and display device including the same{ADHESIVE FILM HAVING VARIABLE ADHESION AND DISPLAY DEVICE COMPRISING THE SAME}

The present invention relates to an adhesive film having a variable adhesive force and a display device comprising the same, specifically, to an adhesive film having a variable adhesive force comprising an adhesive layer whose adhesive force changes with or without UV irradiation and a display device comprising the same .

Recently, various image display devices such as liquid crystal display devices, plasma display devices, electrophoretic display devices, and organic light emitting display devices have been used. In particular, the organic light emitting display device is a next-generation display device having high visibility due to self-luminescence, and has a wide viewing angle, excellent contrast, and high response speed.

As the base substrate of the display panel gradually becomes thinner and more flexible, the display device warps in the display panel during the manufacturing process of the display device, resulting in defects in the final product. Accordingly, in manufacturing a display device, a protective film composed of a reinforcing plate and an adhesive layer is used on a lower portion of the display panel (ie, a lower portion of the base substrate) to protect and support the base substrate of the display panel. In the conventional method using a protective film, after attaching the first film for temporary protection to the back surface of the base substrate, and after removing the first film, patterning the back plate of the bending area or the area requiring bending, and then attaching the second film Method. In this method, there was a hassle to go through several steps such as attaching the first film, removing the first film, patterning step, attaching the second film to the lower portion of the base substrate, and the defect generation rate may be increased in proportion to the complicated process steps.

An object of the present invention is to provide an adhesive film excellent in antistatic properties, heat resistance, and optical properties while the adhesive strength changes depending on whether UV radiation is present or not.

In addition, another object of the present invention is to provide a display device having a low manufacturing cost and excellent productivity by simplifying a manufacturing process of a display device using the above-described adhesive film.

In order to achieve the above technical problem, the present invention is a base substrate; An adhesive layer disposed on at least one surface of the base substrate; And a release film disposed on the adhesive layer, wherein the adhesive layer comprises (a) an alkyl (meth)acrylate polymer having a weight average molecular weight of 100,000 to 500,000 g/mol and a thermal crosslinking agent. Cargo, and (b) a (meth)acrylate-based monomer, a polyfunctional (meth)acrylate-based monomer and a photopolymerizable composition comprising a photoinitiator, wherein the thermosetting composition and the photopolymerizable composition are 30-50: 50-70 It provides an adhesive film having a variable adhesive force, the adhesive strength increase rate (ΔP) of 40 to 200 according to the following equation (1), including as a weight ratio of:

[Equation 1]

(In the above formula,

P ₁ is the initial adhesive strength of the adhesive layer to glass measured by ASTM D3330 before UV irradiation on the adhesive film,

P ₂ is the final adhesive strength of the adhesive layer to glass measured by ASTM D3330 after UV irradiation on the adhesive film).

In addition, the present invention provides a display device including the above-described adhesive film.

The adhesive film according to the present invention is excellent in antistatic property, heat resistance, and optical properties while the adhesive force is changed depending on whether UV radiation is present or not. Therefore, when the adhesive film of the present invention is applied to a display device, antistatic properties, optical properties, and heat resistance of the display device are improved, and there is an effect of increasing process efficiency and reducing a defect rate in manufacturing the display device.

1 is a cross-sectional view schematically showing an adhesive film according to the present invention.
2 is a cross-sectional view schematically showing a display device according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

In the present invention, the glass transition temperature of the A monomer is a theoretical value, and means the glass transition temperature of the homopolymer of A monomer.

<Adhesive film>

1 is a cross-sectional view schematically showing an adhesive film having a variable adhesive force according to the present invention.

The pressure-sensitive adhesive film 10 according to the present invention is a pressure-sensitive adhesive-type film in which adhesive strength is changed depending on whether UV radiation is present or not, and includes a base substrate 11, an adhesive layer 12, and a release film 13 for display devices. In particular, while protecting and supporting (mounting) the lower portion of the display panel of the organic light emitting display device, static electricity can be prevented.

(1) Base description

In the adhesive film 10 according to the present invention, the base substrate 11 is attached to the lower portion of the display panel of the display device (for example, the organic light emitting display device) by the adhesive layer 11 while protecting the lower portion of the display panel ( Part).

As the base substrate 11, any plastic film commonly known in the art can be used without limitation. For example, polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate, polyethylene films, polypropylene films, cellophane, diacetylcellulose films, triacetylcellulose films, acetylcellulose butyrate films, polychlorinated Vinyl film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone And films, polyetherimide films, polyimide films, fluororesin films, polyamide films, acrylic resin films, norbornene-based resin films, and cycloolefin resin films. The plastic film may be transparent or translucent, or may be colored or uncolored. According to an example, the substrate 11 may be polyethylene terephthalate (PET). According to another example, the substrate 11 may be polyimide (PI).

At least one surface of the base substrate 11 of the present invention may be antistatic. In this case, the pressure-sensitive adhesive film of the present invention is excellent in antistatic properties and can prevent static electricity generation, thereby improving workability of the manufacturing process.

An example of the antistatic treatment method is a method of coating at least one surface of the base substrate with an antistatic agent. At this time, the coating method is not particularly limited, for example, cast method, dipping method, roll coating method, gravure coating method, screen printing method, reverse coating method, spray coating method, kiss coating method, die coating method, metallization bar coating method. , Chamber doctor co-coat method, curtain coat method, bar coat method and the like.

Antistatic agents may be used without limitation as long as they are materials that can prevent static electricity in the art. For example, alkyl ammonium acetates, alkyl dimethyl benzyl ammonium salts, alkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, dodecyl trimethyl ammonium chloride, cetrimonium ammonium chloride, octadecyl trimethyl ammonium chloride, alkyl pyridinium salts, oxyalkylene alkyl Cationic surfactants such as amines and polyoxyalkylene alkylamines; Fatty acid soda soaps (e.g., sodium stearate soap, etc.), alkyl sulfates (e.g., sodium lauryl sulfate), alkyl ether sulfates, sodium alkylbenzenesulfonates, sodium alkylnaphthalenesulfonates, dialkylsulfosuccinates, alkyl Anionic surfactants such as phosphates and alkyl diphenyl ether disulfonates; Amphoteric surfactants such as alkylcarboxybetaines; Fatty acid alkylolamide, di(2-hydroxyethyl) alkylamine, polyoxyethylene alkylamine, fatty acid glycerin ester, polyoxyethylene glycol fatty acid ester, sorbitan fatty acid ester, polyoxy sorbitan fatty acid ester, polyoxyethylene alkylphenyl Conductive polymers such as ether, polyoxyethylene alkyl ether, polyethylene glycol, polyoxyethylene diamine, polyether and polyester and polyamide, conductive polymers such as PEDOT:PSS[poly(3,4-ethylenedioxythiophene) polystyrene sulfonate], etc. And nonionic surfactants such as oxypolyethylene glycol (meth)acrylate, and the like, or these may be used alone or in combination of two or more.

The thickness T1 of the base substrate is not particularly limited, and may be, for example, about 25 to 150 μm.

(2) adhesive layer

In the adhesive film 10 according to the present invention, the adhesive layer 12 provides an adhesive force for attaching the base substrate 11 to the lower portion of the display panel of the display device, specifically, the organic light emitting display device.

The adhesive layer 12 of the present invention is in a semi-cured state, and includes (a) a thermoset and (b) a photopolymerizable composition. However, in the present invention, by adjusting the mixing ratio of the thermosetting and photopolymerizable composition to a weight ratio of 30 to 50: 50 to 70, it is possible to control the change in the adhesive strength of the adhesive layer before and after ultraviolet (UV) irradiation.

Specifically, the adhesive layer 12 includes a thermosetting obtained by thermosetting a thermosetting composition comprising an alkyl (meth)acrylate-based polymer and a heat crosslinking agent. The thermoset includes a polymer having a three-dimensional network structure formed by crosslinking linear alkyl (meth)acrylate polymers with a heat crosslinking agent due to a crosslinking reaction between an alkyl (meth)acrylate polymer and a heat crosslinking agent. Components of the photopolymerizable composition, such as (meth)acrylate-based monomer, polyfunctional (meth)acrylate-based monomer and photoinitiator, and optionally photoreactive vinyl-based monomer and/or acrylic acrylate oligomer are dispersed in the thermosetting composition. . When UV is irradiated to the adhesive layer 12, a photopolymerization reaction between a meta)acrylate monomer and a polyfunctional (meth)acrylate monomer, or a photoreactive vinyl monomer and/or an acrylic acrylate oligomer by a photoinitiator The photopolymerization reaction of the liver is induced to form a copolymer comprising a repeating unit derived from each monomer and the oligomer. At this time, the copolymer may be a chain structure or a crosslinked structure. Such a copolymer is formed by intercalating between polymers having a network structure in a thermoset, and as a result, the adhesive layer 12 has an interpenetrating polymer network (IPN) structure. As described above, since the adhesive layer 12 of the present invention includes a thermoset before UV irradiation and a photopolymerizable composition, and includes a heat-UV double cured product after UV irradiation, it is an adhesive layer whose adhesive strength changes depending on whether or not it is irradiated with UV. .

However, the adhesive layer of the present invention easily adheres the base substrate to the lower portion of the panel of the display device prior to UV irradiation, while maintaining the adhesion of the base substrate, and facilitates the base substrate without damaging the adhesive layer or the panel during peeling of the base substrate. On the other hand, the base substrate must be stably attached to the lower portion of the display panel in the manufacturing process of the display device and the final product state after UV irradiation.

Thus, in the present invention, by adjusting the mixing ratio of the thermosetting material and the photopolymerizable composition in the adhesive layer to a weight ratio of 30 to 50: 50 to 70, the adhesive layer 12 has an adhesive strength of 40 to 200 according to Equation 1 below. It has an increase rate (ΔP).

[Equation 1]

(In the above formula,

P ₁ is the initial adhesive strength of the adhesive layer to the glass measured by ASTM D3330 before UV irradiation on the adhesive film,

P ₂ is the adhesive strength of the adhesive layer to glass measured by ASTM D3330 after UV irradiation on the adhesive film,

During the UV irradiation, the UV irradiation amount is about 400 to 2,000 mJ/cm ² , and the UV wavelength is about 365 nm).

If, if the adhesive layer contains less than 30 thermosetting, migration of the photoreactive material occurs before UV irradiation, the physical properties of the adhesive film is lowered, while the adhesive layer contains more than 50 thermosetting If it does, the adhesive strength increase rate (ΔP) may be insufficient.

According to an example, the adhesive layer 12 has a low initial adhesive strength to the glass before UV irradiation of about 15 gf/inch or less, and a high adhesive strength to the glass after UV irradiation of about 500 gf/inch or higher. In this case, the adhesive layer 12 has a large change in adhesive force.

Specifically, the initial adhesive strength of the adhesive layer to the glass before UV irradiation is about 1 to 15 gf/inch, specifically about 5 to 15 gf/inch, and the adhesive strength to the glass after UV irradiation is about 500 to 1,000 gf/ inch, specifically about 700 to 1,000 gf/inch.

Hereinafter, each component of the adhesive layer 12 according to the present invention will be described.

a) thermoset

In the adhesive layer 12 of the present invention, the thermosetting is a main component that realizes the adhesive strength of the adhesive layer before UV irradiation, and is a material formed by thermosetting the thermosetting composition. That is, the thermoset includes a crosslinked structure formed by reaction between an alkyl (meth)acrylate-based polymer and a heat crosslinking agent in the thermosetting composition.

The thermosetting composition includes an alkyl (meth)acrylate-based polymer and a heat crosslinking agent.

The alkyl (meth) acrylate-based polymer is a polymer containing at least one repeating unit derived from an alkyl (meth) acrylate monomer containing an alkyl group of C ₄ to C ₁₇ , among carboxyl and hydroxy groups at the side chain and/or terminal. It contains at least one functional group.

According to an example, the alkyl (meth) acrylate-based polymer may be a hydroxy group-containing alkyl (meth) acrylate-based polymer. In this case, the alkyl (meth)acrylate-based polymer may have a hydroxyl value (OH value) in the range of about 2 to 30 mgKOH/g, specifically, about 2 to 15 mgKOH/g.

The alkyl (meth)acrylate-based polymer has a weight average molecular weight of about 100,000 to 500,000 g/mol, specifically, about 200,000 to 400,000 g/mol. If, when the weight average molecular weight of the alkyl (meth) acrylate-based polymer is outside the above-mentioned range, it affects the formation of the IPN structure, and thus, the variation in adhesive strength can be greatly reduced. Here, the weight average molecular weight means a polystyrene conversion value measured by gel permeation chromatography (GPC).

The heat crosslinking agent is a material that chemically bonds with a carboxyl group and/or a hydroxy group of an alkyl (meth)acrylate-based polymer to form a crosslinked structure, for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, etc. It may be used alone or in combination of two or more.

The isocyanate-based crosslinking agent usable in the present invention is not particularly limited as long as it is a compound containing an isocyanate group known in the art, for example, a bifunctional or higher polyfunctional isocyanate compound, specifically a 2 to 3 functional isocyanate compound, and the like. More specifically, examples of the isocyanate-based crosslinking agent include diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoboron diisocyanate, tetramethylxylene diisocyanate, naphthalene diisocyanate, and any one of the polyols ( ex. trimethylol propane) and the like, but is not limited thereto.

The epoxy-based crosslinking agent usable in the present invention is not particularly limited as long as it is a compound containing an epoxy group known in the art, for example, a bifunctional or higher polyfunctional epoxy compound, specifically a 2-3 functional epoxy compound, and the like. More specifically, examples of the epoxy-based crosslinking agent include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N,N,N,N'-tetraglycidyl ethylenediamine, and glycerin diglycine. Cidyl ether, and the like, but is not limited thereto.

The aziridine-based crosslinking agent usable in the present invention is not particularly limited as long as it is a compound containing an aziridine group known in the art, for example, a bifunctional or higher polyfunctional aziridine compound, specifically 2 to 4 functional aziridine Compounds and the like. More specifically, examples of the aziridine-based crosslinking agent are N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1- Aziridinecarboxamide), triethylene melamine, bisisopropaloyl-1-(2-methylaziridine), tri-1-aziridinylphosphine oxide, pentaerythritol-tris-(beta-(N- Aziridinyl)propionate, trimethylolpropane-tris(beta-N-aziridinyl)propionate, trimethylolpropane-tris(2-methyl-1-aziridinepropionate), and the like. Does not work.

The content of the heat crosslinking agent is adjusted according to the content of the alkyl (meth)acrylate-based polymer, the molecular weight or the content of functional groups in the polymer. For example, in the heat cured product of the adhesive layer, the content of the heat crosslinking agent may range from about 0.001 to 1.5 parts by weight, specifically about 0.01 to 1.05 parts by weight based on 100 parts by weight of the alkyl (meth)acrylate-based polymer. At this time, if the content of the heat crosslinking agent in the thermosetting of the adhesive layer is less than 0.001 part by weight, crosslinking degree may cause migration of the photopolymerizable material and the thermosetting, while the content of the heat crosslinking agent in the thermosetting is 1.5 wt. When the amount is exceeded, an increase in adhesive strength of the adhesive layer after UV irradiation may be inhibited due to an excessive increase in crosslinking density.

b) Photopolymerizable composition

In the adhesive layer 12 of the present invention, the photopolymerizable composition is a photopolymerization reaction by UV irradiation, and is a component that increases the adhesion and adhesion after UV irradiation, and is a monofunctional (meth)acrylate monomer, multifunctional (meta ) Includes an acrylate-based monomer and a photoinitiator, and may further include a photoreactive monofunctional vinyl-based monomer and/or an acrylic acrylate oligomer. These reactants can form a chain, branched and/or crosslinked polymer by photopolymerization.

In one example, the photopolymerizable composition of the adhesive layer includes a monofunctional (meth)acrylate monomer, a polyfunctional (meth)acrylate monomer, and a photoinitiator.

In another example, the photopolymerizable composition of the adhesive layer includes a monofunctional (meth)acrylate monomer, a polyfunctional (meth)acrylate monomer, a photoinitiator, and a photoreactive monofunctional vinyl monomer.

In another example, the photopolymerizable composition of the adhesive layer includes a monofunctional (meth)acrylate monomer, a polyfunctional (meth)acrylate monomer, a photoinitiator, and an acrylic acrylate oligomer.

In another example, the photopolymerizable composition of the adhesive layer includes a monofunctional (meth)acrylate monomer, a polyfunctional (meth)acrylate monomer, a photoinitiator, a photoreactive monofunctional vinyl monomer, and an acrylic acrylate oligomer. .

In the photopolymerizable composition of the present invention, the monofunctional (meth)acrylate-based monomer is a (meth)acrylate-based monomer having one polymerizable functional group that is a polymerizable unsaturated group, such as C ₁ to C ₂₀ alkyl (meth ) May be an acrylate-based monomer. Here, the polymerizable functional group refers to a group involved in the polymerization reaction, such as (meth)acrylate group. At this time, the alkyl group may be straight-chain, branched-chain or cyclic. For example, it may be a monofunctional C ₁ to C ₂₀ alkyl (meth)acrylate-based monomer having a glass transition temperature of about -70 to 0°C.

Specific examples of the monofunctional (meth)acrylate-based monomer usable in the present invention are ethyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl acrylate, isopropyl Acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-methoxyethyl acrylate, 2-ethylbutyl (meth)acrylate, n-octyl (meth)acrylate, caprolactone acrylic Late, Rauli acrylate, tridexyl acrylate, isodexyl (meth)acrylate, and the like, but is not limited thereto.

The monofunctional (meth)acrylate-based monomer may have a molecular weight of about 50 to 400 g/mol.

In the photopolymerizable composition of the present invention, the polyfunctional (meth)acrylate-based monomer is a (meth)acrylate-based monomer having two or more polymerizable functional groups (eg, (meth)acrylate groups) which are polymerizable unsaturated groups. , It is a photoreactive polyfunctional monomer having a higher glass transition temperature than a monofunctional (meth)acrylate monomer. For example, it may be a bifunctional or higher polyfunctional (meth)acrylate-based monomer having a glass transition temperature of about 0 to 180°C, specifically, a 2 to 3-functional (meth)acrylate-based monomer.

Examples of the bifunctional (meth) acrylate monomers include 1,6-hexanediol diacrylate (HDDA), polyethylene glycol diacrylate (PEGDA), glycerin diacrylate, diethylene glycol diacrylate (DEGDA), Triethylene glycol dimethacrylate (TEGDMA), dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), tetraethylene glycol diacrylate (TTEGDA), hydroxypivalic acid neo Alkylene glycol di(meth)acrylate monomers such as pentyl glycol diacrylate (HPNDA), and the like, but are not limited thereto.

Examples of the trifunctional (meth)acrylate-based monomers include trimethylolpropane tri(meth)acrylate, ethoxylated glycerin tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, and propoxylated trimethylol Propane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and the like, but is not limited thereto.

The molecular weight of such a polyfunctional (meth)acrylate-based monomer may be about 50 to 400 g/mol.

In the photopolymerizable composition, the total content of the monofunctional (meth)acrylate-based monomer and the polyfunctional (meth)acrylate-based monomer is about 90 to 99.5 parts by weight based on 100 parts by weight of the photopolymerizable composition, specifically about 93 to 99.5 It may be parts by weight.

Here, the multi-functional (meth) acrylate-based monofunctional for the content of the monomer (W ₂₎ (meth) acrylate content of the monomer (W _1), the ratio (W ₁ / W ₂₎ of can be from about 2 to 33 have. If the polyfunctional (meth)acrylate monomer is used in an excessive amount compared to the monofunctional (meth)acrylate monomer, the adhesive strength after UV irradiation is limited, while the multifunctional (meth)acrylate monomer When too little of a functional (meth)acrylate-based monomer is used, adhesive properties such as heat resistance after UV irradiation, viscoelasticity and storage modulus may be deteriorated.

According to an example, in the photopolymerizable composition of the present invention, the content of the monofunctional (meth)acrylate-based monomer is about 60 to 96.5 parts by weight based on 100 parts by weight of the photopolymerizable composition, specifically about 64 to 95 parts by weight, and multi-tube The content of the functional (meth)acrylate-based monomer may be about 3 to 30 parts by weight, specifically about 4.5 to 16 parts by weight.

The photopolymerizable composition includes a photoinitiator. The photoinitiator is a component that is excited by ultraviolet rays to initiate photopolymerization and can be used without limitation, as long as it is a photodegradable photoinitiator that is directly decomposed into radicals effective to initiate a polymerization reaction.

Examples of such photoinitiators are Irgacure 184, Irgacure 1173, Benzyl dimethyl katal (BDK), DAROCUR TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide), 2,2-Dimethoxy-2-phenylacetophenone (DMPA) , Irgacure 369, Irgacure 651, Irgacure 819, Irgacure 907, Irgacure 127, Omnirad TPO-L (Ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate). These may be used alone or in combination of two or more.

The maximum absorption wavelength of the photoinitiator is not particularly limited as long as it can absorb ultraviolet rays, and may be, for example, in the range of about 230 to 410 nm.

The content of the photoinitiator may be in the range of about 0.5 to 10 parts by weight, specifically about 0.5 to 7 parts by weight based on 100 parts by weight of the photopolymerizable composition.

The photopolymerizable composition of the present invention may further include a photoreactive vinyl-based monomer.

The photoreactive vinyl-based monomer is a monomer capable of photopolymerization by UV by containing a vinyl group, and is a photoreactive monomer having a higher glass transition temperature than a monofunctional (meth)acrylate-based monomer. For example, it may be a monofunctional vinyl-based monomer having a glass transition temperature of about -20 to 100°C.

The photoreactive vinyl-based monomer usable in the present invention is one selected from the group consisting of a carboxyl group, a hydroxy group, an aromatic group of C ₆ to C ₂₀ , a heterocycloalkyl group of C ₃ to C ₂₀ , and an aryloxy group of C ₆ to C ₂₀ It may be a vinyl-based monomer containing the above functional groups.

Specifically, examples of the photoreactive vinyl-based monomer include a monofunctional vinyl-based monomer represented by Formula 1 below, but are not limited thereto.

[Formula 1]

(In the above formula,

R ₂ is each selected from the group consisting of hydrogen, C ₁ ~ C ₂₀ alkyl group, and C ₆ ~ C ₂₀ aryl group,

a and b are each 0 or 1,

R ₃ is a C ₁ ~C ₂₀ alkylene group,

R ₄ is selected from the group consisting of -COOH, -OH, morpholinyl group, C ₆ ~ C ₂₀ aromatic group, C ₃ ~ C ₂₀ heterocycloalkyl group and C ₆ ~ C ₂₀ aryloxy group) .

Examples of the monofunctional vinyl-based monomer represented by Formula 1 include (meth)acrylic acid, fumaric acid, fumaric acid monoester, maleic acid, maleic acid monoester, 2-(meth)acryloyloxyethylphthalic acid, 2-(meth) Carboxyl group-containing vinyl monomers such as acryloyloxyethyl hexahydrophthalic acid; 2-hydroxy ethyl methacrylate (2-HEMA), 2-hydroxy ethyl acrylate (2-HEA), 2-hydroxy propyl acrylate (2-HPA), 4-hydroxy butyl acrylate (4- HBA), hydroxy group-containing (meth)acrylates such as 2-hydroxy propyl methacrylate (2-HPMA); 3 to 15 nuclear atoms such as cyclic trimethylolpropane formal acrylate (CTFA), tetrahydrofurfuryl acrylate (THFA), tetrahydrofurfuryl methacrylate (THFMA) Heterohaloalkyl group-containing (meth)acrylate; Benzyl acrylate, (meth)acryloyl morpholine, Phenol(EO) acrylate], Phenol(EO) ₂ acrylate, and the like, but are not limited thereto.

The molecular weight of the photoreactive vinyl-based monomer may be about 50 to 400 g/mol.

In the photopolymerizable composition, the content of the photoreactive monofunctional vinyl-based monomer is in the range of about 0 to 30 parts by weight based on 100 parts by weight of the photopolymerizable composition, preferably greater than 0 to 30 parts by weight or less, more preferably about 1 to 20 parts by weight It may range from parts by weight.

At this time, the content of the photoreactive vinyl-based monomer is preferably adjusted in consideration of the contents of the monofunctional (meth)acrylate-based monomer and the polyfunctional (meth)acrylate-based monomer.

As an example, the ratio of the total content (W ₁ +W ₃ ) of the monofunctional (meth)acrylate monomer and the photoreactive monofunctional vinyl monomer to the content of the multifunctional (meth)acrylate monomer (W ₂ )[ (W ₁ +W ₃ )/W ₂ ] may be about 3 to 20. If, compared to a monofunctional monomer (monofunctional (meth) acrylate-based monomer and photo-reactive vinyl-based monomer) too much polyfunctional (meth) acrylate-based monomer is used, the adhesive strength after UV irradiation is limited, on the other hand When too small a polyfunctional monomer is used compared to a functional monomer, adhesive properties, viscoelasticity and storage modulus may be deteriorated after UV irradiation.

As another example, light reactive vinyl content of the monomer (W ₃₎ a monofunctional (meth) content of the acrylate-based monomer for the ratio of the ratio of _{(W 1) (W 1 /} W 3) is about 3 to 98, preferably It may be 3 to 20.

The photopolymerizable composition of the present invention may further include an acrylic acrylate oligomer.

The acrylic acrylate oligomer is a multifunctional oligomer having a linear structure, as well as having excellent ductility and excellent flexibility. Therefore, the acrylic acrylate oligomer can photopolymerize with the monomers described above to form a polymer, thereby improving the adhesion and viscoelasticity of the adhesive layer.

Examples of acrylic acrylate oligomers usable in the present invention include Miramer S5242 (Miwon Co.), but are not limited thereto.

The weight average molecular weight of these acrylic acrylate oligomers is about 1,000 to 30,000 g/mol, specifically about 5,000 to 20,000 g/mol. If, when the weight average molecular weight of the acrylic acrylate oligomer is less than 1,000 g/mol, the elastic modulus and heat resistance may decrease after UV curing, while when the weight average molecular weight of the acrylic acrylate oligomer exceeds 30,000 g/mol, the process It may lead to inhibition of ease and deterioration of adhesive strength.

In the photopolymerizable composition of the present invention, the content of the acrylic acrylate oligomer is about 0 to 10 parts by weight based on 100 parts by weight of the photopolymerizable composition, preferably greater than about 0 to 10 parts by weight or less, more preferably about 1 to 7 parts by weight It can be a subrange.

The photopolymerizable composition of the present invention affects the physical properties of the adhesive layer other than the monofunctional (meth)acrylate monomer, polyfunctional (meth)acrylate monomer, photoreactive vinyl monomer and/or acrylic acrylate oligomer described above. As long as it does not fall, it may further include additives such as antistatic agents, antioxidants, dispersants, antifoaming agents, thickeners, plasticizers, tackifying resins, and polymerization inhibitors. These additives may be used in a range of contents commonly used in the art, for example, about 0.001 to 10% by weight, specifically about 0.01 to 5% by weight, more specifically about 0.01 to 3% by weight, based on the total amount of the photopolymerizable composition. %.

Meanwhile, the adhesive layer of the present invention may include an antistatic agent. Specifically, the antistatic agent may be included in the thermosetting composition and/or the photopolymerizable composition. At this time, the content of the antistatic agent is not particularly limited, and can be appropriately adjusted within a conventional range known in the art. For example, the antistatic agent may be included in an amount of about 0.1 to 5% by weight, specifically about 0.5 to 2% by weight based on the total amount of the adhesive layer.

The thickness of the adhesive layer 12 is not particularly limited. However, in order to effectively implement the adhesive strength before and after UV irradiation, the thickness of the adhesive layer may be in the range of about 5 to 50 μm, preferably about 10 to 30 μm.

The adhesive layer 12 of the present invention increases the viscoelasticity by increasing the storage modulus after UV irradiation.

According to one example, the adhesive layer 12 has a storage modulus change rate (G) of about 750 to 5,000%, specifically about 1000 to 5000%, according to Equation 2 below.

[Equation 2]

(In the above formula,

G ₁ is the initial storage modulus at 25° C. of the adhesive layer before UV irradiation on the adhesive film,

G ₂ is the final storage modulus at 25° C. of the adhesive layer after UV irradiation on the adhesive film).

In addition, the adhesive layer of the present invention in the initial storage modulus of about 0.01 to 0.08 MPa, specifically about 0.04 to 0.05 MPa before UV irradiation, about 0.3 to 1.5 MPa after UV irradiation, specifically about 0.5 to 0.98 MPa final storage modulus As a result, the storage modulus changes significantly.

In addition, the adhesive layer has a thermal decomposition temperature of about 5% by weight measured by thermogravimetric analysis (TGA) before UV irradiation on the adhesive film, and is about 140 to 190°C, after UV irradiation on the adhesive film, thermogravimetric analysis (TGA) 5 wt% reduction pyrolysis temperature measured by) may be about 240 to 340 ℃. As described above, since the adhesive layer of the present invention has excellent high heat resistance after UV irradiation, it can proceed without defects even at high temperature processes such as ACF process at about 180°C after UV irradiation.

(3) Release film

In the adhesive film 10 according to the present invention, the release film 13 is disposed on the adhesive layer 12 until the adhesive film is applied to the display device to prevent the adhesive layer 12 from being contaminated from foreign substances in the external environment. The adhesive film is peeled off before being applied to the lower portion of the display panel.

As the release film 13, a conventional material known in the art may be used, and may be, for example, a silicone-based release film, a UV-blocking release film, or the like.

In particular, when the release film is a UV-blocking release film, the adhesive film of the present invention has excellent stability over time with respect to ultraviolet (UV) light, so that the adhesive layer by ultraviolet light (approximately 100 to 380 nm) present in natural and fluorescent lamps A change in adhesive force can be prevented. In one example, when the pressure-sensitive adhesive film of the present invention includes a UV-blocking release film, the UV blocking rate at a wavelength of about 330 to 380 nm is about 90 to 100%.

The UV-blocking release film is not particularly limited as long as it is a release film having a UV-blocking or absorbing function known in the art. Release films, or release films produced by laminating two types of materials having different refractive indices.

In the present invention, the release force of the release film is not particularly limited, for example, the release force of the release film for the adhesive layer measured by ASTM D3330 may be about 1 to 5 gf/inch.

Moreover, the thickness of a release film is not specifically limited. For example, the ratio (T3/T2) of the thickness (T3) of the release film to the thickness (T2) of the adhesive layer may be about 60 to 100. In this case, the pressure-sensitive adhesive film of the present invention may have a surface resistance of about 10 ¹⁰ mm 2 /m 2 or less.

The adhesive film having a variable adhesive strength according to the present invention described above is excellent in ease of peeling before UV irradiation and adhesiveness after UV irradiation. That is, the adhesive film of the present invention can be easily removed without peeling off the film or damage to the display panel when peeling before UV irradiation, while stably maintaining the state attached to the display panel after UV irradiation to protect the lower portion of the display panel, I can support. In addition, since the adhesive film of the present invention can have a suitable adhesive force for each process step by controlling the presence or absence of UV irradiation or the amount of UV irradiation during manufacture of the display device, it is possible to improve the process efficiency and reduce the defect rate. . Moreover, the adhesive film of the present invention has a surface resistance of about 10 ¹⁰ to 10 ⁷ mm 2 /m 2, and is excellent in antistatic properties. In addition, the adhesive film of the present invention has a haze of about 1 to 6%, and a total light transmittance (TT) at a wavelength of about 400 to 700 nm is about 90% or more, as well as excellent optical properties, heat resistance, UV stability is also excellent.

The adhesive film having a variable adhesive strength according to the present invention can be manufactured by a conventional method known in the art, except for using an adhesive layer.

In one example, a method of manufacturing an adhesive film having a variable adhesive strength according to the present invention comprises the steps of (i) mixing a thermosetting composition and a photopolymerizable composition in a weight ratio of 30-50:50-70 to form an adhesive composition; (ii) forming an adhesive layer by coating and thermosetting the adhesive composition on the first surface of the base substrate; And (iii) placing a release film on the adhesive layer, followed by lamination. However, it is not limited only by the above manufacturing method, and the steps of each process may be modified or selectively mixed as necessary.

Hereinafter, each step of manufacturing the adhesive film of the present invention will be described.

(i) Formation of adhesive composition

The adhesive composition of the present invention is formed by mixing a thermosetting composition and a photopolymerizable composition in a weight ratio of 30-50:50-70.

Here, the thermosetting composition includes an alkyl (meth) acrylate-based polymer and a heat crosslinking agent, and the photopolymerizable composition includes a monofunctional (meth) acrylate-based monomer, a multifunctional (meth) acrylate-based monomer and a photoinitiator, and is optional As a photo-reactive vinyl-based monomer and / or acrylic acrylate oligomer may be further included. Descriptions of the components of each of these compositions are the same as those described in the adhesive layer of the adhesive film, and thus are omitted.

(ii) Formation of adhesive layer

The adhesive layer is formed by coating and thermosetting the adhesive composition on one surface of the base substrate.

At this time, as a method of applying the adhesive composition on the base substrate, conventional coating methods in the art, for example, dip coating method, air knife coating method, curtain coating method, wire bar coating method, gravure coating method, comma coat Method, slot coating method, extrusion coating method, spin coating method, slit scanning method, inkjet method and the like.

In the present invention, the thermosetting process can be suitably carried out within conventional conditions known in the art. For example, heat curing may be performed at about 70 to 150°C for about 1 to 10 minutes, and aging may be performed at about 40 to 60°C for about 24 to 72 hours as needed.

The adhesive layer formed as described above is in a semi-cured state, meaning a gel fraction of about 85 to 95%.

(iii) Lamination of release film

Thereafter, a release film is laminated on the adhesive layer to obtain an adhesive film.

The lamination step may be appropriately performed within a conventional range known in the art, and may be performed under a temperature condition of about 20 to 60°C. As an example, it may be manufactured through a lamination process having a heating roll of the above-described temperature conditions.

As described above, the adhesive film having a variable adhesive strength according to the present invention is an adhesive changeable film having an increased adhesive strength with or without UV irradiation, and can be applied to various fields requiring different adhesive strength for each manufacturing process. In addition, the adhesive film of the present invention can be applied to various fields requiring excellent peelability, adhesiveness, antistatic property, heat resistance, optical properties, and UV stability. For example, in manufacturing a display device (eg, an organic light emitting display device), the adhesive film of the present invention can be used to protect and support the base substrate of a thin and flexible display panel.

In one example, the present invention provides a display device including the adhesive film 10 described above, specifically, an organic light emitting display device.

2, the display device 100 of the present invention includes a display panel 110; And an adhesive film 10 having a variable adhesive force disposed under the display panel. At this time, the above-described adhesive film 10 is applied in a state where the release film 13 is removed. That is, in the display device of the present invention, the adhesive film 10 having a variable adhesive force comprises an adhesive layer 12 contacting a lower portion of the display panel 110 and a base substrate 11 disposed on the adhesive layer. Includes. The adhesive film 10 not only protects and supports the lower portion of the display panel 110, but also prevents static electricity from occurring in the display panel.

Specifically, the display device of the present invention includes a base substrate (not shown) (eg, glass, quartz, ceramic, plastic, polymer film, etc.), a driving circuit portion (not shown) disposed on one surface of the base substrate; And an organic light emitting device (not shown) connected to the driving circuit part. And an adhesive film 10 having a variable adhesive force, disposed on one surface (specifically, the other surface of the base substrate) of the display panel, wherein the adhesive film 10 is an adhesive layer contacting the other surface of the base substrate. (12); And a base substrate 11 disposed on the adhesive layer.

In manufacturing the display device 100 of the present invention, after the adhesive film 10 is attached to the lower portion of the display panel by a constant pressure, a portion of the adhesive film can be removed by laser irradiation or the like as necessary. At this time, since the adhesive film has an initial adhesive strength to glass of about 15 gf/inch or less, specifically about 5 to 15 gf/inch, it can be easily peeled off without damaging the film or damaging the display panel. Thereafter, the adhesive layer of the adhesive film is completely cured (gel fraction: 92 to 99) by UV irradiation (UV irradiation amount: about 400 to 2,000 mJ/cm ² , wavelength: about 365 nm), so that the adhesive film is at the bottom of the display panel. Is firmly attached to. At this time, the adhesive film has a final adhesive strength to glass of about 500 gf/inch or more, specifically about 500 to 1,000 gf/inch, and an adhesive strength increase rate (ΔP) of about 40 to 200.

Hereinafter, the present invention will be described in detail through examples as follows. However, the following examples are only to illustrate the present invention, the present invention is not limited by the following examples.

[ Example 1]-Preparation of adhesive film

1-1. Preparation of adhesive composition

Each component was mixed according to the composition shown in Table 1 below to prepare a thermosetting composition (crude A) and a photopolymerizable composition (crude B), respectively, and then mixed to prepare an adhesive composition. The specifications of the raw materials constituting each composition listed in Table 1 are shown in Table 3 below. In Table 1 below, in the crude liquid A, the content units of each component are based on 100 parts by weight of A1, and in the crude liquid B, the content units of each component are based on 100 parts by weight of the crude liquid B.

1-2. Preparation of variable adhesive film

On one side of the base film PET film (thickness: 75um), the adhesive composition prepared in Example 1-1 was applied, followed by thermal curing at 100° C. for 3 minutes to obtain an adhesive layer (gel fraction: 92%, thickness: 15um). Thereafter, a silicone release film (thickness: 25 μm) was laminated on the adhesive layer to prepare an adhesive film having a variable adhesive force. In Tables 1 and 2, P ₁ is the initial adhesive strength of the adhesive layer to glass before UV irradiation, P ₂ is the final adhesive strength of the adhesive layer to glass after UV irradiation, and ΔP is the rate of increase in adhesive strength according to Equation 1 to be.

[ Example 2~9 and Comparative example 1~ 5]-Adhesion Production of film

The adhesive compositions and adhesive films of Examples 2 to 9 and Comparative Examples 1 to 5 were prepared in the same manner as in Example 1, except that each component was mixed according to the compositions shown in Tables 1 and 2 below. The specifications of the raw materials constituting each composition described in Tables 1 to 2 are shown in Table 3 below.

[ Experimental Example 1]-Property evaluation

The physical properties of the adhesive variable adhesive films prepared in Examples 1 to 10 and Comparative Examples 1 to 5 were measured according to the following measurement method, and the results are shown in Table 4.

1) Adhesive strength

① P ₁ measurement: Before UV irradiation, according to the ASTMD3330 test method, after attaching the adhesive film to the glass and stabilizing for 20 minutes, the adhesive force of the adhesive film peeling off the glass was measured.

② P ₂ measurement: According to the ASTMD3330 test method, the adhesive film is attached to the glass and then stabilized for 20 minutes. Thereafter, UV was irradiated, and the adhesive strength at which the adhesive film peeled off the glass was measured. At this time, the UV irradiation amount was 1,000 mJ/cm 2, and the UV wavelength was about 365 nm.

2) Storage Modulus

Using the DMA 8000 equipment (Perkin Elmer Co.), the initial storage modulus of the adhesive layer at 25°C in the range of -40 to 300°C (1 Hz) was confirmed. Subsequently, after irradiating UV to the adhesive film, the final storage modulus of the adhesive layer at 25° C. in a range of 40 to 300° C. (1 Hz) was checked using a DMA 8000 device (Perkin Elmer).

3) Haze and light transmittance

Haze and light transmittance (550 nm) were measured using NDH 7000 (Nippon denshoku Co.).

4) Surface resistance

The surface resistance of the sample was measured under test voltage 100V using ST-4 (SIMCOION).

5) UV protection rate

Carry 5000 UV-vis-NIR (Agilent Technologies) equipment was used to measure UV transmittance in the region of 320 to 450 nm while the silicone release film was attached.

6) Heat resistance

TGA 550 (TA instruments 社) equipment was used to measure the 5% weight loss temperature point of the adhesive film. Thereafter, after irradiating UV to the adhesive film, a temperature point of 5% weight loss of the adhesive film was measured using a TGA 550 (TA instruments 社) equipment.

10: adhesive film, 11: base substrate,
12: adhesive layer, 13: release film,
100: display device, 110: display panel

Claims (23)

Base substrate;
An adhesive layer disposed on at least one surface of the base substrate; And
Release film disposed on the adhesive layer
Including,
The adhesive layer
(a) a thermoset of a thermosetting composition comprising an alkyl (meth)acrylate-based polymer having a weight average molecular weight of 100,000 to 500,000 g/mol and a heat crosslinking agent, and
(b) a photopolymerizable composition comprising a (meth)acrylate-based monomer, a multifunctional (meth)acrylate-based monomer and a photoinitiator,
The adhesive film having a variable adhesive force, wherein the adhesive strength increase rate (ΔP) according to Equation 1 below is 40 to 200, including the thermosetting composition and the photopolymerizable composition in a weight ratio of 30 to 50:50 to 70:
[Equation 1]

(In the above formula,
P ₁ is the initial adhesion strength of the adhesive layer to glass measured by ASTM D3330 before UV irradiation on the adhesive film,
P ₂ is the final adhesive strength of the adhesive layer to glass measured by ASTM D3330 after UV irradiation on the adhesive film). According to claim 1,
The alkyl (meth) acrylate-based polymer has a hydroxyl value (OH value) of 2 to 30 mgKOH/g adhesive film. According to claim 1,
In the thermosetting of the adhesive layer, the content of the heat crosslinking agent is based on 100 parts by weight of an alkyl (meth)acrylate-based polymer, which is formed by curing a thermosetting composition in the range of 0.001 to 1.5 parts by weight, an adhesive film. According to claim 1,
The (meth)acrylate-based monomer is an alkyl (meth)acrylate monomer having a glass transition temperature of -70 to 0°C. According to claim 1,
The polyfunctional (meth) acrylate-based monomer is a 2 to 4 functional (meth) acrylate monomer having a glass transition temperature of 0 to 180 ℃ adhesive film. According to claim 1,
The total amount of the (meth)acrylate-based monomer and the multifunctional (meth)acrylate-based monomer is an adhesive film in a range of 90 to 99.5 parts by weight based on 100 parts by weight of the photopolymerizable composition. According to claim 1,
The polyfunctional (meth) acrylate based on the content of the monomer (W ₂₎ (meth) acrylate content of the monomer ratios of _{(W 1) (W 1 /} W 2) is 2 to 33 a, pressure-sensitive adhesive film. According to claim 1,
The photopolymerizable composition includes a photoreactive monofunctional vinyl-based monomer having a higher glass transition temperature than the (meth)acrylate-based monomer; And acrylic acrylate oligomer further comprises one or more selected from the group consisting of, adhesive film. The method of claim 8,
The photoreactive monofunctional vinyl-based monomer is a vinyl-based monomer having a glass transition temperature of -20 to 100°C, an adhesive film. The method of claim 8,
The content of the photoreactive monofunctional vinyl-based monomer is more than 0 parts by weight to 30 parts by weight or less based on 100 parts by weight of the photopolymerizable composition, the adhesive film. The method of claim 8,
Ratio of the total content (W ₁ +W ₃ ) of the (meth)acrylate monomer and the photoreactive monofunctional vinyl monomer to the content of the multifunctional (meth)acrylate monomer (W ₂ ) [(W ₁ + W ₃ )/W ₂ ] is 3 to 20, adhesive film. The method of claim 8,
The acrylic acrylate oligomer is an acrylic acrylate oligomer having a weight average molecular weight of 1,000 to 30,000 g/mol. The method of claim 8,
The acrylic acrylate oligomer content is more than 0 parts by weight to 10 parts by weight or less based on 100 parts by weight of the photopolymerizable composition, the adhesive film. According to claim 1,
The adhesive layer has an initial adhesive strength of 15 gf/inch or less with respect to glass before UV irradiation on the adhesive film, and an initial adhesive strength of 500 gf/inch or more with respect to glass after UV irradiation on the adhesive film Having an adhesive film. According to claim 1,
The adhesive layer is an adhesive film having a storage modulus change rate (G) of 750 to 5,000% according to Equation 2 below:
[Equation 2]

(In the above formula,
G ₁ is the initial storage modulus at 25° C. of the adhesive layer before UV irradiation on the adhesive film,
G ₂ is the final storage modulus at 25° C. of the adhesive layer after UV irradiation on the adhesive film). According to claim 1,
The adhesive layer has a 5% by weight loss thermal decomposition temperature measured by thermogravimetric analysis (TGA) before UV irradiation on the adhesive film is 140 to 190°C;
After irradiating the adhesive film with UV, the 5% by weight reduction pyrolysis temperature measured by thermogravimetric analysis (TGA) is 240 to 340°C. According to claim 1,
The base substrate is an antistatic treatment on at least one surface, the adhesive film. According to claim 1,
The release film is an adhesive film that is a silicone-based release film. The method of claim 18,
The silicone-based release film is an adhesive film that is a UV-blocking silicone-based release film. The method of claim 19,
An adhesive film having a UV blocking rate of 90 to 100% at a wavelength of 330 to 380 nm. According to claim 1,
An adhesive film having a surface resistance of 10 ¹⁰ to 10 ⁷ mm 2 /m 2. According to claim 1,
An adhesive film having a haze of 1 to 6% and a total light transmittance (TT) of 90% or more at a wavelength of 550 nm. A display device comprising the adhesive film having the variable adhesive force according to any one of claims 1 to 22.

Images