KR20170116900A - Adhesive composition for optical use, method of producing the same, and adhesive film for optical use - Google Patents

Abstract

(Meth) acryl-based copolymer containing a structural unit derived from a first monomer and a structural unit derived from a second monomer, wherein the first monomer is a (meth) acrylate-based monomer having an alkyl group of 9 to 20 carbon atoms , The alkyl group includes at least one selected from the group consisting of a linear alkyl group, a branched alkyl group, a cyclic alkyl group, and a combination thereof, and the second monomer includes a hydroxyl group-containing (meth) acrylate having 6 to 20 carbon atoms Sensitive adhesive composition for optical use, which is a monomer based on a photopolymerization initiator.

Description

TECHNICAL FIELD [0001] The present invention relates to a pressure-sensitive adhesive composition for optical use, a process for producing the pressure-sensitive adhesive composition for optical use and a pressure-

An optical adhesive composition, a process for producing an optical adhesive composition, and an optical adhesive film.

Electronic devices having touch screen functions such as smart phones and tablet PCs include touch screen panels capable of inputting and manipulating information by touching and displays such as LCDs or OLEDs, There is a problem that the visibility is deteriorated and consequently the performance of the electronic device is deteriorated.

Accordingly, the air gap between the touch screen panel and the display is filled with an adhesive or the like to improve visibility.

Examples of such a pressure sensitive adhesive include an OCA (optically clear adhesive) pressure-sensitive adhesive or an OCR (Optically Clear Resin) pressure sensitive adhesive. The pressure sensitive adhesive may be formed of a material including an acrylic polymer or the like, There is a difference in the form applied to the filling process. The OCA adhesive is applied to the process in film form, while OCR is applied in liquid form.

Normally, the OCA adhesive film can be provided to a customer in a rolled state or a sheet state with a release film adhered to both sides, and polyethylene terephthalate (PET), silicone, etc. are mainly used as a material of the release film .

In one embodiment of the present invention, there is provided a pressure-sensitive adhesive composition for optical applications which realizes excellent touch sensitivity, excellent high-temperature high-humidity reliability, and excellent optical characteristics.

In another embodiment of the present invention, there is provided an optical adhesive film which realizes excellent touch sensitivity, excellent high temperature and high humidity reliability, and excellent optical characteristics.

In another embodiment of the present invention, there is provided a process for producing the optical adhesive composition.

However, the technical problem to be solved by the present invention is not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

In one embodiment of the present invention, there is provided a (meth) acrylic copolymer comprising a structural unit derived from a first monomer and a structural unit derived from a second monomer, wherein the first monomer is an alkyl group having from 9 to 20 carbon atoms (Meth) acrylate monomer, wherein the alkyl group includes at least one selected from the group consisting of a linear alkyl group, a branched alkyl group, a cyclic alkyl group, and a combination thereof, and the second monomer has 6 to 20 carbon atoms (Meth) acrylate-based monomer having a hydroxyl group.

(Meth) acrylate monomer having at least two kinds of monomers such as an alkyl group (meth) acrylate monomer and a hydroxyl group-containing (meth) acrylate monomer as a (meth) acrylate monomer having a large number of carbon atoms By including the (meth) acryl-based copolymer formed, there is an advantage that the dielectric constant can be realized at a sufficiently low level. At the same time, high-temperature and high-humidity reliability, optical characteristics and peel strength can be maintained at a good level.

The weight ratio of the first monomer to the second monomer in the total copolymerizable monomer component forming the (meth) acrylic copolymer may be about 1: 0.05 to about 1: 0.4, more specifically about 1: 0.12 to about 1: 0.25.

When the (meth) acrylic copolymer is contained at a relative weight ratio within the above range, physical properties such as the weight average molecular weight and the hydroxyl value of the (meth) acrylic copolymer are appropriately controlled so that the optical adhesive composition achieves excellent low dielectric constant, excellent high temperature and high humidity reliability, .

In one embodiment, the hydroxyl value (OH value) of the (meth) acrylic copolymer may be from about 5 mg KOH / g to about 35 mg KOH / g.

The weight average molecular weight of the (meth) acrylic copolymer may be, for example, about 500,000 g / mol to about 4,000,000 g / mol, and specifically about 1,000,000 g / mol to about 3,000,000 g / mol.

The glass transition temperature of the (meth) acrylic copolymer may be, for example, about -39 캜 to about 10 캜, and specifically about -30 캜 to about 0 캜.

In another embodiment of the present invention, there is provided an optical adhesive film formed by photo-curing the optical adhesive composition.

The dielectric constant of the adhesive film measured at about 100 Hz can be, for example, about 2.0 to about 3.5, and more specifically about 2.5 to about 3.2. By having a low level of permittivity in the above range, the degree of change of the capacitance can be sufficiently reduced to effectively improve the touch sensitivity, thereby preventing malfunction and further reducing the power loss and increasing the energy efficiency.

The average peel strength of the adhesive film measured at a temperature of about 25 캜, a peeling speed of about 300 mm / min, and a peeling angle of about 180 캜 is about 1.5 kgf / in to about 3.0 kgf / in .

The optical pressure-sensitive adhesive film may have a light transmittance of about 90% or more and a haze of 1.0% or less according to the measurement conditions of ASTM D1003.

The optical adhesive film may be included in a liquid crystal display device and used for attaching a touch screen panel and a liquid crystal panel, and may be applied to, for example, an OCA (optically clear adhesive) adhesive film.

In another embodiment of the present invention, a polymerizable composition comprising a copolymerizable monomer component comprising a first monomer and a second monomer is subjected to a polymerization reaction to form a (meth) acrylic copolymer, Wherein the first monomer is a (meth) acrylate monomer having an alkyl group of 9 to 20 carbon atoms, and the alkyl group may be a linear alkyl group, a branched alkyl group, a cyclic alkyl group, or a combination thereof Wherein the second monomer is a hydroxyl group-containing (meth) acrylate-based monomer having 5 to 20 carbon atoms.

The optical adhesive composition and the optical adhesive film can realize excellent touch sensitivity, excellent high-temperature high-humidity reliability, and excellent optical characteristics.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

In one embodiment of the present invention, there is provided a (meth) acrylic copolymer comprising a structural unit derived from a first monomer and a structural unit derived from a second monomer, wherein the first monomer is an alkyl group having from 9 to 20 carbon atoms (Meth) acrylate monomer, wherein the alkyl group includes at least one selected from the group consisting of a linear alkyl group, a branched alkyl group, a cyclic alkyl group, and a combination thereof, and the second monomer has 6 to 20 carbon atoms (Meth) acrylate-based monomer having a hydroxyl group.

In this specification, the carbon number may mean the total number of carbon atoms contained in a given monomer.

In addition, the cyclic alkyl group may include a cycloalkyl group, a bicycloalkyl group, or both.

Specifically, the (meth) acrylic copolymer may be a polymer obtained by polymerizing polymerizable monomers including the first monomer and the second monomer, and the (meth) acrylic copolymer may be a A structural unit derived from the first monomer, and a structural unit derived from the second monomer.

Generally, an optical adhesive is made of a composition containing only a polymer formed from an acrylic monomer containing an alkyl group having a small number of carbon atoms. The alkyl groups having a low carbon number in the cured product of such a composition have a volume occupied by them, The dielectric constant tends to increase. Accordingly, the touch sensitivity of the touch screen panel and the like is lowered, so that malfunctions are increased and power loss due to frequency is intensifying.

Accordingly, in one embodiment of the present invention, the optical pressure-sensitive adhesive composition comprises an alkyl (meth) acrylate-based monomer having at least one alkyl group and a hydroxyl group-containing (meth) (Meth) acryl-based copolymer formed from a copolymerizable monomer component simultaneously containing the (meth) acrylic copolymer. At the same time, high-temperature and high-humidity reliability, optical characteristics and peel strength can be maintained at a good level.

Accordingly, the optical pressure-sensitive adhesive composition of the present invention can effectively improve the touch sensitivity, thereby preventing malfunction, and also reducing power loss and realizing excellent energy efficiency.

The first monomer may be an alkyl group-containing (meth) acrylate monomer having 9 to 20 carbon atoms, and the alkyl group may be an alkyl group substituted or unsubstituted with a predetermined alkyl group. When the alkyl group is substituted with a predetermined alkyl group, And may be substituted with 1 to 17 alkyl groups.

The first monomer may be, for example, methyldecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, (Meth) acrylate, decyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (Meth) acrylate, isododecyl (meth) acrylate, isotridecyl (meth) acrylate, isopentadecyl (meth) acrylate, (Meth) acrylate, isooctadecyl (meth) acrylate, isobodecyl (meth) acrylate, isooctadecyl (meth) acrylate, isooctadecyl Acrylic But is not limited to, at least one selected from the group consisting of combinations thereof. Specifically, the first monomer may include at least one selected from the group consisting of isooctadecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, and combinations thereof, Accordingly, the dielectric constant can be reduced to a sufficiently low level.

The second monomer is a (meth) acrylate-based monomer containing a hydroxyl group-containing (meth) acrylate-based monomer having 6 to 20 carbon atoms, that is, an alkyl group substituted with a hydroxyl group, and includes, for example, 2-hydroxyethylmethacryl (Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl But are not limited to, at least one selected from the group consisting of ethylene glycol methacrylate, 2-hydroxypropylene glycol (meth) acrylate, and combinations thereof.

In one embodiment, the second monomer does not include a carboxyl group, an ethoxy group, or an amine group. Accordingly, it is possible to prevent corrosion of a predetermined product to which a film or the like formed from the optical adhesive composition is applied while realizing excellent low dielectric constant and excellent high-temperature adhesive property, and to effectively prevent occurrence of yellowing.

When the second monomer contains a carboxyl group, it can corrode a predetermined electrode included in a touch sensor such as ITO. When the second monomer contains an amine group, high temperature adhesive property may be deteriorated and yellowing may easily occur. The dielectric constant may be excessively increased.

The weight ratio of the first monomer to the second monomer in the total copolymerizable monomer component forming the (meth) acrylic copolymer may be about 1: 0.05 to about 1: 0.4, more specifically about 1: 0.12 to about 1: 0.25.

When the (meth) acrylic copolymer is contained at a relative weight ratio within the above range, physical properties such as the weight average molecular weight and the hydroxyl value of the (meth) acrylic copolymer are appropriately controlled so that the optical adhesive composition achieves excellent low dielectric constant, excellent high temperature and high humidity reliability, .

The content of the first monomer in the total copolymerizable monomer component forming the (meth) acrylic copolymer may be about 75 wt% to about 95 wt%.

By including the first monomer in the content within the above range, excellent peel strength and excellent tackiness can be realized.

In addition, the content of the second monomer in the total copolymerizable monomer forming the (meth) acrylic copolymer may be, for example, about 5 wt% to about 25 wt%. By including the second monomer in the content within the above range, appropriate peeling force and excellent high-humidity reliability can be realized.

In one embodiment, the (meth) acrylic copolymer further comprises a structural unit derived from a third monomer, and the third monomer contains an epoxy group, or has 7 carbon atoms containing an alkyl group substituted with an epoxide group To 20 (meth) acrylate-based monomers.

The epoxide group may be, for example, a 1,2-epoxide group, a 1,3-epoxide group, a 1,4-epoxide group, or a 1,5-epoxide group as a so-called cyclic ether group.

The third monomer may, for example, include, but is not limited to, glycidyl (meth) acrylate, tetrahydrofuryl (meth) acrylate, or both.

The content of the third monomer in the total copolymerizable monomer component forming the (meth) acrylic copolymer may be about 1 wt% to about 20 wt%. As described above, when the third monomer is further contained, the above-mentioned weight percentages of the first monomer and the second monomer can be appropriately changed under the condition that the weight ratio thereof is satisfied.

In one embodiment, the hydroxyl value (OH value) of the (meth) acrylic copolymer may be from about 5 mg KOH / g to about 35 mg KOH / g. By including it in the content within the above range, excellent low dielectric constant and excellent high temperature high humidity reliability can be realized at the same time.

The weight average molecular weight of the (meth) acrylic copolymer may be, for example, about 500,000 g / mol to about 4,000,000 g / mol, and specifically about 1,000,000 g / mol to about 3,000,000 g / mol. By having the weight average molecular weight within the above range, the viscosity of the optical pressure-sensitive adhesive composition can be appropriately adjusted to realize sufficient high temperature and high humidity reliability and peeling force, and the workability can be improved when formed into a film shape or the like.

The glass transition temperature of the (meth) acrylic copolymer may be, for example, about -39 캜 to about 10 캜, and specifically about -30 캜 to about 0 캜. By having a glass transition temperature within the above range, sufficient heat resistance can be realized, and bubble and whitish phenomenon can be prevented under high temperature and high humidity conditions, and workability can be improved when formed into a film shape or the like.

The optical adhesive composition may further comprise at least one selected from the group consisting of a photoinitiator, a photo-curing agent, a solvent, other additives, and combinations thereof.

The photoinitiator may be, for example, 1-hydroxy-cyclohexyl-phenol-ketone, 2-methyl-1- [4- (methylthio) phenyl] -2- morpholinopropane- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 2- 2-methylpropan-1-one, benzophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy- 1-propan-1-one, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethanthraquinone, 2-methylthioxanthone, But are not limited to, at least one selected from the group consisting of 2,4-dimethylthioxanthone, 2,4-diethyloxthone and combinations thereof.

When the photo initiator is further included, the photoinitiator may be included in an amount of about 0.05 to about 0.5 parts by weight based on 100 parts by weight of the (meth) acrylic copolymer. When the content is within the above range, the initial radical reaction can be sufficiently promoted by light irradiation, and the residual photoinitiator is not present in the final product after completion of the reaction, so that deterioration of physical properties due to migration can be prevented.

The photo-curing agent may be a polyfunctional curing agent and may include, for example, pentaerythritol triacrylate (PETIA), trimethylolpropane triacrylate (TMPTA), 1,6-hexanediol diacrylate (HDDA) But is not limited thereto.

When the photo-curing agent is further included, it may be included in an amount of about 0.01 to about 1 part by weight based on 100 parts by weight of the (meth) acrylic copolymer. When the content is within the above range, the photo-curing reaction can proceed sufficiently, and the speed of the curing reaction can be appropriately controlled to uniformly realize the curing degree as a whole.

The solvent may not be included in the case of using bulk polymerization in which a solvent is not required, and when it is prepared by solution polymerization or the like, for example, ethyl acetate, tetrahydrofuran, toluene, methyl ethyl ketone And combinations thereof. However, the present invention is not limited thereto.

The other additives may be appropriately included within the range not affecting the effects of the invention and may include at least one selected from the group consisting of, for example, ultraviolet stabilizer, antioxidant, plasticizer and combinations thereof.

In another embodiment of the present invention, there is provided an optical adhesive film formed by photo-curing the optical adhesive composition. The optical sticky composition is as described above in one embodiment.

The (meth) acrylic copolymer contained in the optical pressure-sensitive adhesive composition contains a (meth) acrylate monomer having a large number of carbon atoms, specifically, a (meth) acrylate monomer having an alkyl group and a The optical adhesive film formed from the optical adhesive composition is advantageous in that the dielectric constant can be realized at a sufficiently low level since the optical adhesive film formed from the copolymerizable monomer component containing at least two monomers of the monomers simultaneously. At the same time, high-temperature and high-humidity reliability, optical characteristics and peel strength can be realized at a high level.

The photocuring may be, for example, UV curing and, for example, UV irradiation may be performed using a metal halide lamp.

The UV irradiation is, for example, but can be carried out in a quantity of light of about 0.5J / cm ² to about 5.0J / cm ^2, it is not limited to this.

The dielectric constant of the adhesive film measured at about 100 Hz can be, for example, about 2.0 to about 3.5, and more specifically about 2.5 to about 3.2. By having a low level of permittivity within the above range, the amount of change in capacitance can be reduced to a sufficiently small value, thereby effectively improving touch sensitivity, thereby preventing malfunction and further reducing power loss, thereby improving energy efficiency.

The average peel strength of the adhesive film measured at a temperature of about 25 캜, a peeling speed of about 300 mm / min, and a peeling angle of about 180 캜 is about 1.5 kgf / in to about 3.0 kgf / in .

By having a peeling force within the above range, sufficient adhesive force or adhesive force is formed to prevent lifting phenomenon under high-temperature and high-humidity conditions, and it is possible to realize excellent reworkability without causing damage to the adhered surface by peeling.

In another embodiment, the optical pressure-sensitive adhesive film may have a light transmittance of about 90% or more and a haze of 1.0% or less according to a measurement condition of ASTM D1003, and specifically a light transmittance of about 90% to 95% , And a haze from about 0.05% to about 1%. By having light transmittance and haze within the above range, excellent optical characteristics can be realized.

The thickness of the adhesive film may be about 100 탆 to about 250 탆. By having a thickness within the above range, the air gap between the touch screen panel and the display can be sufficiently filled to realize excellent visibility, and the cost can be reduced.

The optical adhesive film may be included in a liquid crystal display device and used for attaching a touch screen panel and a liquid crystal panel, and may be applied to, for example, an OCA (optically clear adhesive) adhesive film.

Accordingly, the liquid crystal display device may include a structure in which the touch screen panel, the optical adhesive film, and the liquid crystal panel are sequentially stacked, and the touch screen panel and the liquid crystal panel may be formed of a material known in the art And is not particularly limited.

In another embodiment of the present invention, there is provided a process for producing the optical adhesive composition. The method comprises the steps of: preparing a pressure-sensitive adhesive composition for optical applications by performing a polymerization reaction on a polymerizable composition comprising a first monomer and a second monomer, thereby forming a (meth) acrylic copolymer; Wherein the first monomer is an alkyl group-containing (meth) acrylate monomer having 9 to 20 carbon atoms, and the alkyl group is selected from the group consisting of a linear alkyl group, a branched alkyl group, a cyclic alkyl group, and combinations thereof And the second monomer may be a (meth) acrylate monomer having a hydroxyl group of 5 to 20 carbon atoms.

The optical adhesive composition described above in one embodiment can be produced by the above production method. The first monomer and the second monomer are as described above in one embodiment.

In the above production process, a polymerization reaction may be carried out on the polymerization composition containing the copolymerizable monomer component to prepare an optical pressure-sensitive adhesive composition, and the polymerization reaction may be a photopolymerization reaction.

The photo-polymerization reaction, for example, can be carried out by irradiating light to the light amount of about 0.5J / cm ² to about 5.0J / cm ^2, but can be performed by irradiating UV, it not limited to this.

(Meth) acrylic copolymer which is a polymer in which the copolymerizable monomer component is polymerized by the polymerization reaction, thereby to produce an optical adhesive composition comprising the same.

The method may further comprise preparing the polymerization composition by mixing the copolymerizable monomer components, wherein the weight ratio of the first monomer to the second monomer is about 1: 0.05 to about 1: 0.4. The above-mentioned polymerization composition may be prepared by mixing. Specifically, the weight ratio of these may be from about 1: 0.12 to about 1: 0.25.

Average molecular weight and hydroxyl value of the (meth) acryl-based copolymer are appropriately controlled by mixing the (meth) acrylic copolymer at a relative weight ratio within the above-mentioned range so that the optical adhesive composition achieves excellent low dielectric constant, excellent high temperature and high humidity reliability, .

Also, the polymerization composition may be prepared such that the content of the first monomer is about 75% by weight to about 95% by weight.

By mixing the first monomer in the content within the above range, excellent peel strength and excellent tackiness can be realized.

Further, the composition for polymerization may be prepared such that the content of the second monomer is, for example, about 5 wt% to about 25 wt%.

By mixing the second monomer in the content within the above range, the high temperature and high humidity reliability can be realized at a high level.

In the step of preparing the polymerization composition, the (meth) acrylate monomer containing a carboxyl group, an ethoxy group or an amine group may not be mixed. Accordingly, it is possible to prevent corrosion of a predetermined product to which a film or the like formed from the optical adhesive composition is applied while realizing excellent low dielectric constant and excellent high-temperature adhesive property, and to effectively prevent occurrence of yellowing.

When the second monomer contains a carboxyl group, it can corrode a predetermined electrode included in a touch sensor such as ITO. When the second monomer contains an amine group, high temperature adhesive property may be deteriorated and yellowing may easily occur. The dielectric constant may be excessively increased.

(Meth) acrylate monomer containing an epoxy group or an alkyl group substituted with an epoxide group, and the third monomer is further mixed in the step of preparing the composition for polymerization. Acrylate-based monomer. The third monomer is as described above in one embodiment.

The third monomer may be mixed in the copolymerizable monomer component such that its content is from about 1% to about 20% by weight.

The (meth) acrylic copolymer may have a hydroxyl value (OH value) of about 5 mgKOH / g to about 35 mgKOH / g. By forming at a hydroxyl value within the above range, excellent low dielectric constant and excellent high-temperature high-humidity reliability can be realized at the same time.

The (meth) acrylic copolymer may have a weight average molecular weight of, for example, about 500,000 g / mol to about 4,000,000 g / mol, and specifically about 1,000,000 g / mol to about 3,000,000 g / mol . When the weight average molecular weight is within the above range, the viscosity of the optical pressure-sensitive adhesive composition can be appropriately adjusted to achieve sufficient high-temperature and high-humidity reliability and peeling force, and workability can be improved when formed into a film shape or the like.

The (meth) acrylic copolymer may have a glass transition temperature of, for example, about -39 ° C to about 10 ° C, and specifically about -30 ° C to about 0 ° C. By forming at a glass transition temperature within the above range, sufficient heat resistance can be realized and occurrence of bubbles and whitewashed phenomenon under high temperature and high humidity conditions can be prevented, and workability can be improved when formed into a film shape or the like.

In the step of producing the optical pressure-sensitive adhesive composition, at least one selected from the group consisting of a photoinitiator, a photo-curing agent, a solvent, other additives, and combinations thereof may be further added after the (meth) acrylic copolymer is formed.

Hereinafter, specific embodiments of the present invention will be described. However, the embodiments described below are only intended to illustrate or explain the present invention, and the present invention should not be limited thereto.

Example

Example  One

70 parts by weight of octadecyl acrylate, 15 parts by weight of isobornyl acrylate and 15 parts by weight of hydroxybutyl acrylate as a second monomer were mixed and stirred as a first monomer to prepare a polymerization composition.

(Meth) acryl-based copolymer was formed by irradiating UV light to the polymerization composition at a light amount of 3 J / cm ² to conduct a photopolymerization reaction. Subsequently, 0.1 part by weight of a photoinitiator And 0.1 part by weight of a photopolymerization initiator were mixed and stirred to prepare an optical pressure-sensitive adhesive composition.

Example  2

20 parts by weight of dodecyl acrylate 50, 20 parts by weight of octadecyl acrylate, 15 parts by weight of isobornyl acrylate and 15 parts by weight of hydroxypropyl acrylate as a second monomer were mixed and stirred to prepare a polymerization composition Was prepared in the same manner as in Example 1, except that the pressure-sensitive adhesive composition for optical use was prepared.

Example  3

Except that 40 parts by weight of dodecyl acrylate 40, octadecyl acrylate as the first monomer and 15 parts by weight of a copolymerizable monomer component of hydroxypropyl acrylate as a second monomer were mixed and stirred to prepare a composition for polymerization The pressure-sensitive adhesive composition for optical applications was prepared under the same conditions and procedures as in Example 1.

Comparative Example  One

Except that 70 parts by weight of butyl acrylate, 15 parts by weight of isobornyl acrylate, and 15 parts by weight of hydroxypropyl acrylate were mixed and stirred to prepare a polymerization composition. To prepare an optical adhesive composition.

Comparative Example  2

Except that 70 parts by weight of butyl acrylate, 15 parts by weight of isobornyl acrylate, and 15 parts by weight of hydroxybutyl acrylate were mixed and stirred to prepare a polymerization composition. To prepare an optical adhesive composition.

Experimental Example

The properties of the respective (meth) acrylic copolymers formed in Examples 1-3 and Comparative Examples 1 and 2 were evaluated and shown in the following Table 1, and the optical adhesives according to Examples 1-3 and Comparative Examples 1 and 2 The composition was irradiated with UV of 3 mJ / cm ² to prepare each optical adhesive film, and the physical properties of each of the optical adhesive films were evaluated and are shown in Table 2 below.

Assessment Methods

Experimental Example  One: Hydroxyl value

Measuring apparatus: Erlenmeyer flask (200 ml), air cooling tube (30 cm), pipette (5 ml, 10 ml), buret (50 ml)

Measurement method: The hydroxyl value of each (meth) acrylic copolymer formed in Example 1-3 and Comparative Examples 1 and 2 was measured using an acetic anhydride-pyridine method according to JIS K 8004-1961.

Specifically, the measurement was carried out in the following order.

(1) A mixture of a (meth) acrylic copolymer and 5 ml of an anhydrous acetic acid-pyridine solution was added to an Erlenmeyer flask, and the mixture was shaken 5 times or more. The mixture was allowed to react in a oil bath for 1 hour and 30 minutes.

(2) 1 ml of distilled water was added, and the mixture was shaken 5 times or more. Then, the mixture was allowed to stand in a oil bath for 10 minutes to promote hydrolysis.

(3) After taking out from the oil bath and keeping it at room temperature for 10 minutes, the inner wall of the cooler was washed with 10 ml of acetone and then shaken 5 times or more, 3 to 4 drops of phenolphthalein indicator were added and titrated with 0.5N KOH standard solution.

Then, the hydroxyl value of each (meth) acrylic copolymer was calculated using the following equation (2).

[Equation 2]

Hydroxyl value (mgKOH / g) = [(B-C) x f x 28.05] / S + D

B: Amount (ml) of a 0.5 mol / l potassium hydroxide ethanol solution used in the blank test,

C: The amount (ml) of the 0.5 mol / l potassium hydroxide ethanol solution used in the sample,

f: a factor of 0.5 mol / l potassium hydroxide ethanol solution

S: mass of the sample (g)

D: acid value

28.05: 1/2 of the molecular weight of potassium hydroxide

Experimental Example  2: Glass transition temperature

Measuring method: Each (meth) acrylic copolymer formed in Example 1-3 and Comparative Examples 1 and 2 was measured at a heating rate of 10 캜 / minute using a differential scanning calorimeter (TA instruments, DSC Q20) .

Experimental Example  3: Permittivity

Measurement method: Each of the optical adhesive films prepared by photo-curing the optical adhesive composition according to Example 1-3 and Comparative Examples 1 and 2 was measured with a permittivity meter (Agilent, E4980A) at 100 kHz according to ASTM D150-11 ).

Experimental Example  4: Average Peel force

Measurement method: One of the release faces of each optical adhesive film prepared by photo-curing the optical adhesive composition according to Example 1-3 and Comparative Examples 1 and 2 was peeled off, laminated on a 50 占 퐉 untreated PET film, Each specimen was prepared by cutting one inch wide and 180 mm long.

The glass substrate was reciprocally pressed five times on a base plate with a 2 Kg rubber roll on an 80 mm x 180 mm glass substrate, and then allowed to stand at room temperature for 30 minutes. Then, the peel force was measured using a Texture Analyzer (TA instrument).

Experimental Example  5: Light transmittance  And Hayes

Measuring method: For each optical adhesive film prepared by photocuring the optical adhesive composition according to Example 1-3 and Comparative Examples 1 and 2, a spectrophotometer (Konica) was applied to a film having a thickness of (m) according to ASTM D1003 Minolta, CM-5).

Experimental Example  6: High temperature and high humidity  responsibility

Measuring method: Each of the optical adhesive films prepared by photo-curing the optical adhesive composition according to Example 1-3 and Comparative Examples 1 and 2 was adhered to a glass substrate, and each optical adhesive The film was placed in a high-temperature and high-humidity chamber and allowed to stand at 85 ° C and 85% RH for 24 hours, and then taken out.

Subsequently, each of the pressure-sensitive adhesive films was observed visually to see whether bubbles were generated and whether white spots were generated, and evaluated in three stages of excellent, normal, and defective as described below.

Excellent (○): White spots and air bubbles are not generated.

Normal (△): White spots did not occur, but 1 to 10 bubbles having a diameter of 100 μm or less occurred.

Defective (X): White spots occur and more than 10 bubbles having a diameter of 100 μm or less are generated.

Hydroxyl value (mgKOH / g) Glass transition temperature (캜) Example 1 23.8 -7 Example 2 24.6 -9 Example 3 27.8 -21 Comparative Example 1 24.8 -40 Comparative Example 2 22.7 -43

permittivity Average peel force (kgf / in) Light transmittance (%) Haze (%) High temperature and high humidity
responsibility Example 1 2.8 2.6 92.8 0.15 O Example 2 3.0 2.8 92.9 0.2 O Example 3 3.1 2.0 93.2 0.16 O Comparative Example 1 4.0 2.1 93.1 0.18 Δ Comparative Example 2 4.3 1.9 92.8 0.22 X

As shown in Table 1 and Table 2, in the case of each (meth) acrylic copolymer formed in Example 1-3, the hydroxyl group value and the glass transition temperature were both formed within a suitable range, It has been confirmed that each of the optical adhesive films formed from the composition realizes an excellent low dielectric constant and thus the touch sensitivity can be effectively improved and that the high temperature and high humidity reliability is also excellent.

On the other hand, in the case of each of the (meth) acrylic copolymers formed in Comparative Examples 1 and 2, the glass transition temperature was too low, and each optical adhesive film formed from the optical adhesive composition containing each of the It is clearly evaluated that the touch sensitivity is inferior and the reliability of high temperature and high humidity is also inferior.

Claims (20)

(Meth) acrylic copolymer containing a structural unit derived from a first monomer and a structural unit derived from a second monomer,
The first monomer is a (meth) acrylate monomer having an alkyl group of 9 to 20 carbon atoms, and the alkyl group includes at least one selected from the group consisting of a linear alkyl group, a branched alkyl group, a cyclic alkyl group, and combinations thereof In addition,
The second monomer is a (meth) acrylate monomer having 6 to 20 carbon atoms and a hydroxyl group
Adhesive composition for optics.
The method according to claim 1,
Wherein the second monomer does not contain a carboxyl group, an ethoxy group, or an amine group
Adhesive composition for optics.
The method according to claim 1,
The weight ratio of the first monomer to the second monomer in the total copolymerizable monomer component forming the (meth) acrylic copolymer is 1: 0.05 to 1: 0.4
Adhesive composition for optics.
The method according to claim 1,
Wherein the (meth) acrylic copolymer further comprises a structural unit derived from a third monomer,
The third monomer may be a (meth) acrylate monomer having 7 to 20 carbon atoms containing an epoxide group or containing an alkyl group substituted with an epoxide group
Adhesive composition for optics.
5. The method of claim 4,
The content of the third monomer in the total copolymerizable monomer component forming the (meth) acrylic copolymer is 1 wt% to 20 wt%
Adhesive composition for optics.
The method according to claim 1,
When the hydroxyl value (OH value) of the (meth) acrylic copolymer is from 5 mgKOH / g to 35 mgKOH / g
Adhesive composition for optics.
The method according to claim 1,
When the (meth) acrylic copolymer has a weight average molecular weight of 500,000 g / mol to 4,000,000 g / mol
Adhesive composition for optics.
The method according to claim 1,
When the (meth) acrylic copolymer has a glass transition temperature of -39 ° C to 10 ° C
Adhesive composition for optics.
The method according to claim 1,
At least one selected from the group consisting of photoinitiators, photo-curing agents, other additives, and combinations thereof.
Adhesive composition for optics.
An optical adhesive film formed by photo-curing an optical adhesive composition according to any one of claims 1 to 9.
11. The method of claim 10,
The dielectric constant of the adhesive film measured at 100 Hz is 2.0 to 3.5
Optical adhesive film.
12. The method of claim 11,
The average peel strength of the adhesive film measured at a temperature of 25 캜, a peeling speed of 300 mm / min, and a peeling angle of 180 is measured with respect to a base material made of glass of 1.5 kgf / in to 3.0 kgf / in
Optical adhesive film.
12. The method of claim 11,
A light transmittance of 90% or more and a haze of 1.0% or less according to the measurement conditions of ASTM D1003
Optical adhesive film.
12. The method of claim 11,
Wherein the thickness of the adhesive film is 100 m to 250 m
Optical adhesive film.
Preparing a pressure-sensitive adhesive composition for optical by forming a (meth) acrylic copolymer by performing a polymerization reaction on a polymerization composition comprising a copolymerizable monomer component comprising a first monomer and a second monomer,
The first monomer is a (meth) acrylate monomer having an alkyl group of 9 to 20 carbon atoms, and the alkyl group includes at least one selected from the group consisting of a linear alkyl group, a branched alkyl group, a cyclic alkyl group, and combinations thereof In addition,
Wherein the second monomer is a hydroxyl group-containing (meth) acrylate monomer having 5 to 20 carbon atoms.
16. The method of claim 15,
And preparing a polymerization composition by mixing the copolymerizable monomer components,
The first monomer and the second monomer are mixed so that the weight ratio of the first monomer to the second monomer is 1: 0.05 to 1: 0.4 to prepare the polymerization composition
A method for producing an optical adhesive composition.
17. The method of claim 16,
In the step of preparing the composition for polymerization, the (meth) acrylate monomer containing a carboxyl group, an ethoxy group or an amine group is not mixed
A method for producing an optical adhesive composition.
17. The method of claim 16,
In the step of preparing the composition for polymerization, a third monomer is further mixed, and the third monomer is a (meth) acrylate having 7 to 20 carbon atoms containing an epoxide group or an alkyl group substituted with an epoxide group Monomeric
A method for producing an optical adhesive composition.
16. The method of claim 15,
The (meth) acrylic copolymer has a hydroxyl value (OH value) of 5 mgKOH / g to 35 mgKOH / g
A method for producing an optical adhesive composition.
16. The method of claim 15,
The (meth) acrylic copolymer is formed so that its glass transition temperature is from -39 ° C to 10 ° C
A method for producing an optical adhesive composition.