KR102104663B1 - Adhesive composition for touch panel and adhesive film - Google Patents

Abstract

Disclosed is a pressure-sensitive adhesive composition for a touch panel and a pressure-sensitive adhesive film that has little deformation due to external stimuli such as pressing and stamping, and has excellent adhesion performance.
The pressure-sensitive adhesive composition for a touch panel according to the present invention includes a (meth) acrylic acid ester-based monomer, an acid monomer and an acrylic resin photopolymerized from a photopolymerization initiator, wherein the acrylic resin has a weight average molecular weight of 10 ⁶ or more, and the (meth) acrylic acid The ester-based monomer is characterized by containing an alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms.

Description

Adhesive composition for touch panel and adhesive film {ADHESIVE COMPOSITION FOR TOUCH PANEL AND ADHESIVE FILM}

The present invention relates to a pressure-sensitive adhesive composition, and more particularly, to a pressure-sensitive adhesive composition for a touch panel and a pressure-sensitive adhesive film that can minimize deformation due to external stimuli.

In the electrical industry or the electronics industry, in order to bond parts, or in particular to bond two or more different materials or parts to each other, adhesives having excellent adhesive strength on both sides must be used. Specifically, the display is composed of a touch screen panel (TSP) and a liquid crystal module, and the touch screen panel has a laminated structure such as a conductive film and a transparent substrate. In this case, an adhesive is used when attaching each layer to the stacked structure of the touch screen panel, and an adhesive is also used when attaching the touch screen panel and the liquid crystal module.

As an example, a polyethylene terephthalate (PET) film is used as a substrate, and there is a conductive film formed of indium tin oxide (ITO) on one surface. An adhesive film having an adhesive layer formed on one surface of the conductive film is laminated on a conductive glass, a reinforcing material, or a decorative film.

In general, the pressure-sensitive adhesive layer is formed by curing the pressure-sensitive adhesive composition containing an acrylic polymer. The pressure-sensitive adhesive layer has an excellent effect in peeling force or adhesive strength, but has a disadvantage of high deformation rate due to external stimulation and high anti-deterioration effect.

Therefore, there is a need for an adhesive having excellent adhesion performance and anti-pressing performance.

Background art related to the present invention is Republic of Korea Patent Publication No. 10-2015-0100037 (2015.09.02. Published), the above document discloses an adhesive resin composition for a touch screen panel and an adhesive film using the same.

An object of the present invention is to provide a pressure-sensitive adhesive composition for a touch panel that is less deformed by external stimuli, such as pressing and stamping, and has excellent durability and adhesive performance.

Another object of the present invention is to provide an adhesive film using the adhesive composition.

The pressure-sensitive adhesive composition for a touch panel according to the present invention for achieving the above object includes a (meth) acrylic acid ester-based monomer, an acid monomer and an acrylic resin photopolymerized from a photopolymerization initiator, and the acrylic resin has a weight average molecular weight of 10 ⁶ Above, the (meth) acrylic acid ester-based monomer is characterized in that it contains an alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms.

The content of the acid monomer may be 5 to 30 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester-based monomer.

The acid monomer may include one or more of acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, fumaric acid, maleic acid, and itaconic acid.

The content of the photopolymerization initiator may be 0.01 to 2 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester-based monomer.

The photopolymerization initiator may include one or more of benzoin-based compounds, hydroxy ketone-based compounds, amino ketone-based compounds, and phosphine oxide-based compounds.

The composition may further include an additive comprising at least one of a curing agent and a UV stabilizer.

The adhesive film for a touch panel according to the present invention for achieving the other object is a base film layer; And (meth) acrylic acid ester monomers, acid monomers, and is water curing of the pressure-sensitive adhesive composition containing the acrylic resin curing light from the photo-polymerization initiator sensitive adhesive layer, from and including, the storage modulus of the pressure-sensitive adhesive layer 25 ~ 65 ℃ 10 ⁵ ~ 10 ^It is characterized by being ⁷ Pa.

In addition, the thickness of the pressure-sensitive adhesive layer may be 20 ~ 200㎛.

The pressure-sensitive adhesive composition according to the present invention contains an acrylic resin having a weight average molecular weight of 10 ⁶ or more, so that it is less deformed by external stimuli such as pressing and sticking, and has excellent adhesion performance.

In addition, even if it is left in a high temperature (85 ° C) high humidity (85%) environment for more than 200 hours, air bubbles and cloudiness are not generated, and an adhesive film having excellent durability can be provided.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and the ordinary knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

Hereinafter, an adhesive composition for a touch panel and an adhesive film according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

According to the present invention, by manufacturing an acrylic resin containing a photopolymerization initiator, it is possible to provide an adhesive composition for a touch panel excellent in durability and high temperature reliability.

The acrylic resin is prepared through a photopolymerization reaction. The photopolymerization reaction is easy to control the polymerization reaction because it can be polymerized at room temperature compared to the general thermal polymerization. In addition, since the reaction time is short, there is an effect that can further increase the process efficiency, it is easy to prepare a resin having a weight average molecular weight of about 10 ⁶ or more.

The pressure-sensitive adhesive composition for a touch panel according to the present invention includes an acrylic resin formed by photopolymerization from a (meth) acrylic acid ester-based monomer, an acid monomer, and a photopolymerization initiator.

The (meth) acrylic acid ester-based monomer includes an alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms. More specifically, the alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms is an alkyl (meth) acrylate having a linear alkyl group having 1 to 14 carbon atoms and an alkyl (meth) having a branched alkyl group having 1 to 14 carbon atoms. Acrylate.

When the number of carbon atoms in the alkyl group exceeds 20 and becomes too long, the cohesive force of the cured product decreases, and control of the glass transition temperature may become difficult.

As an alkyl (meth) acrylate having a linear alkyl group having 1 to 14 carbon atoms, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, pentyl (Meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, tetradecyl (meth) acrylate, and the like.

As an alkyl (meth) acrylate having a branched alkyl group having 1 to 14 carbon atoms, isopropyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, 2-ethylhexyl (meth ) Acrylates and the like.

The acid monomer may control the glass transition temperature of the acrylic resin, and may include one or more of acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, fumaric acid, maleic acid, and itaconic acid.

The content of the acid monomer may be 5 to 30 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester-based monomer. When the content of the acid monomer is less than 5 parts by weight, the cohesive force of the acrylic resin may be lowered, and it may be difficult to control the glass transition temperature of the pressure-sensitive adhesive composition. Conversely, when it exceeds 30 parts by weight, the content of the polar monomer is high, and polymerization of the acrylic resin may be difficult, and the pressure-sensitive adhesive composition may harden, resulting in deterioration in peel strength and adhesive strength.

The acrylic resin is prepared by photopolymerization. The acrylic resin may include a photopolymerization initiator that generates radicals by light irradiation. By performing stable polymerization for a short reaction time within about 2 hours without artificial heat supply, an acrylic resin having a weight average molecular weight of 10 ⁶ or more can be prepared.

The photopolymerization initiator may include one or more of benzoin-based compounds, hydroxy ketone-based compounds, amino ketone-based compounds, and phosphine oxide-based compounds.

For example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylanoanoacetophenone, 2,2-dime Methoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1one, 1-hydroxy-cyclohexylphenylketone, 2- Methyl-1- [4- (methylthio) phenyl] -2-morpholinyl-1-propanone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2 -Methylanthraquinone, 2-ethylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4- Diethylthioxanthone, benzyldimethylketal, acetophenone dimethylketal, p-dimethylamino benzoic acid ester, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone] and 2 , 4,6-trimethylbenzoyl- Phenyl-phosphine oxide and the like.

The content of the photopolymerization initiator may be 0.01 to 2 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester-based monomer. When the content of the photopolymerization initiator is less than 0.01 part by weight, the content of the photopolymerization initiator is insufficient, and thus, polymerization or curing reaction is not smoothly performed, which may affect reliability. Conversely, when the content of the photopolymerization initiator exceeds 2 parts by weight, there are problems in that durability is vulnerable because many molecules having a short binding length are generated.

The acrylic resin may be prepared by irradiating ultraviolet light at a wavelength of approximately 100 to 500 nm to initiate a photopolymerization reaction.

At this time, the weight average molecular weight of the acrylic resin is preferably 10 ⁶ or more, more preferably 10 ⁶ ~ 5.0X10 ⁷ .

When the weight average molecular weight of the acrylic resin is 10 ⁶ or more, an adhesive composition having excellent workability and mechanical strength may be provided. When the weight average molecular weight is less than 10 ⁶ , sufficient cohesion in the pressure-sensitive adhesive composition is not obtained in a high temperature (85 ° C.) and high humidity (85%) environment, so that cloudiness or bubbles may occur. Conversely, when the weight average molecular weight exceeds 5.0X10 ⁷ , it is difficult to secure an adhesive composition having stable physical properties even at high temperatures.

The composition may further include an additive comprising at least one of a curing agent and a UV stabilizer.

The curing agent may include a bifunctional acrylate, for example, 1,4-butanedioldi (meth) acrylate, 1,6-hexanedioldi (meth) acrylate, neopentyl glycol di (meth) acrylic Late, polyethylene glycol di (meth) acrylate, neopentylglycoladipate di (meth) acrylate, hydroxyl puivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl ) Di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) acrylate, allylated cyclohexyldi (meth) acrylate, tricyclodecanedi Methanol (meth) acrylate, dimethylol dicyclopentane di (meth) acrylate, ethylene oxide-modified hexahydrophthalic acid di (meth) acrylate, tricyclodecane dimethanol (meth) acrylic Sites and the like.

The content of the curing agent may be 0.1 to 5 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester-based monomer, but is not limited thereto.

The UV stabilizer may be a benzotriazole-based UV stabilizer such as Tinuvin 234 and Tinuvin 360 manufactured by Ciba.

The content of the UV stabilizer may be 0.1 to 3 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester monomer, but is not limited thereto.

In addition, the pressure-sensitive adhesive composition may include a solvent such as toluene, acetone, methanol, and benzene, but it is preferable to prepare a solvent-free pressure-sensitive adhesive composition to produce a uniform pressure-sensitive adhesive film with minimal thickness variation. When the pressure-sensitive adhesive composition does not contain a solvent, it is possible to prevent the generation of bubbles caused by the volatilization process of the solvent or the lowering of leveling. In addition, a uniform adhesive film having a thickness of 100 µm or more can be effectively produced, thereby improving process efficiency.

In addition, the pressure-sensitive adhesive composition may further include a filler, a brightener, a dispersant, etc. within a range that does not impair the physical properties of the composition, in addition to the acrylic resin containing a photopolymerization initiator.

The adhesive film of the present invention includes an adhesive layer and a base film layer.

The pressure-sensitive adhesive layer is a cured product of the pressure-sensitive adhesive composition comprising a (meth) acrylic acid ester-based monomer, an acid monomer and an acrylic resin photopolymerized from a photopolymerization initiator.

At this time, the pressure-sensitive adhesive layer of the present invention, the storage modulus is maintained at 10 ~ ⁵ ~ 10 ⁷ Pa at 25 ~ 65 ℃, it is possible to minimize the deformation by external stimulation.

The storage elastic modulus was measured by applying a constant force to the pressure-sensitive adhesive layer while changing the temperature by an ARES instrument (Theometric Scientific). A large storage elastic modulus means that the elasticity of the pressure-sensitive adhesive layer is large, and the larger the storage elastic modulus, the more the deformation against external pressing can be minimized.

The thickness of the pressure-sensitive adhesive layer may be 20 ~ 200㎛. When the thickness of the pressure-sensitive adhesive layer is maintained in the above range, sufficient adhesive strength can be secured, and the pressure-sensitive adhesive layer can be stably maintained.

The pressure-sensitive adhesive composition of the present invention is an acrylic resin having a weight average molecular weight of 10 ⁶ or more, and when applied to a substrate for a touch panel, it can provide a pressure-sensitive adhesive layer having excellent adhesion performance and anti-pressing performance.

In addition, the present invention can provide a touch panel including the adhesive layer and the conductive plastic film on which the conductive layer is formed. In the conductive plastic film, an ITO (conductive metal oxide) layer is formed on the base film.

Looking at the specific embodiment of the pressure-sensitive adhesive composition and an adhesive film for a touch panel as follows.

1. Preparation of adhesive film

Examples 1-3 and Comparative Examples 1-2

After mixing 100 parts by weight of ethylhexyl acrylate (2-EHA) with acrylic acid (AA) and benzoin (Sigma Aldrich) as the photopolymerization initiator, respectively, in the contents shown in [Table 1] below, and irradiating with ultraviolet rays having a wavelength of 360 nm. By doing so, an adhesive composition for a touch panel comprising an acrylic resin was prepared. At this time, the weight average molecular weight of the acrylic resin is as described in [Table 1]. After applying the composition on the base film, an adhesive film having an adhesive layer formed on the base film was prepared.

Example 3 further comprises 3 parts by weight of hardener HDDA (1,6-hexanediol diacrylate) with respect to 100 parts by weight of 2-EHA in the adhesive composition.

[Table 1]

2. Method for evaluating physical properties and results

1) Measurement of cloudiness and bubble generation: Under the conditions of 85 ° C and 85% RH, the adhesive film attached to the glass was stored for 200 hours to observe whether white spots or bubbles were observed.

2) Measurement of adhesive force: The adhesive film was made of 25mmX40mm (horizontal X length), and the adhesive film was reciprocated once on a glass glass with a 2kg roller. The adhesive strength at the time of pulling and peeling at 300 mm / min in the direction of 180 ° C with respect to the attached adhesive film surface was measured.

3) Hardness: A PET film having a thickness of 50 μm was laminated on the adhesive layer of the adhesive film. The PET film was given a load of 200 g at a rate of 1.0 mm / min using a text analyzer, and the pressed depth of the adhesive film was measured.

4) Storage elastic modulus: The storage elastic modulus was measured by applying a jig force to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film by an ARES device (Theometric Scientific) at 25 ° C.

[Table 2]

When referring to the results of [Table 1] and [Table 2], it can be seen that Examples 1 to 3 have the performance of preventing bubbles and clouding in a high temperature and high humidity environment compared to Comparative Examples 1 and 2, . In Comparative Examples 1 and 2, the storage elastic modulus is out of the range of 10 ⁵ to 10 ⁷ Pa, and it can be seen that the pressing depth of the adhesive film is deep, so that deformation due to external stimulation occurs.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and may be manufactured in various different forms, and having ordinary knowledge in the technical field to which the present invention pertains. It will be understood that a person can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (8)

(Meth) acrylic acid ester-based monomers, acid monomers, photopolymerization initiator and a curing agent containing photopolymerized acrylic resin,
The acrylic resin has a weight average molecular weight of 10 ⁶ or more,
The (meth) acrylic acid ester-based monomer includes an alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms, and the content of the photopolymerization initiator exceeds 0.01 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester-based monomer. Less than 2 parts by weight,
The curing agent is a pressure-sensitive adhesive composition, characterized in that the bifunctional acrylate.
According to claim 1,
The content of the acid monomer is a pressure-sensitive adhesive composition, characterized in that 5 to 30 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester-based monomer.
According to claim 1,
The acid monomer is a pressure-sensitive adhesive composition comprising at least one of acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid.
delete According to claim 1,
The photopolymerization initiator is a benzoin-based compound, a hydroxy ketone-based compound, an amino ketone-based compound, a pressure-sensitive adhesive composition comprising at least one of a phosphine oxide-based compound.
According to claim 1,
The composition is an adhesive composition characterized in that it further comprises a UV stabilizer.
A base film layer; And
(Meta) acrylic acid ester-based monomer, an acid monomer, a photopolymerization initiator and an acrylic resin photopolymerized from a curing agent. Less than, the curing agent is a cured product of the pressure-sensitive adhesive composition of a bifunctional acrylate; includes;
The adhesive film, characterized in that the storage modulus of the adhesive layer is 10 ⁵ ~ 10 ⁷ Pa at 25 ~ 65 ℃.
The method of claim 7,
The thickness of the pressure-sensitive adhesive layer is an adhesive film, characterized in that 20 ~ 200㎛.