KR20220012752A - Acrylic adhesive composition for optical device, acrylic adhesives film for optical device thermo-cured therefrom, touch screen panel and optical device having the same - Google Patents

Abstract

Disclosed in the present invention is an optical acrylic adhesive composition comprising acrylic copolymer comprising a polymerization unit made of fluorinated (meth)acrylate and an alkyl (meth)acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms. An adhesive film based on the optical acrylic adhesive composition of the present invention can impart touch sensitivity due to low dielectric constant thereof, and can be usefully used as an adhesive film for an optical device such as a touch screen panel due to good step absorption performance and high temperature and humidity reliability thereof.

Description

Optical acrylic adhesive composition, optical acrylic adhesive film including cured product, touch screen panel and optical device having the same OPTICAL DEVICE HAVING THE SAME}

The present invention relates to an optical acrylic pressure-sensitive adhesive composition that can be used for adhesion of various optical elements, particularly optical elements to a touch screen panel, an optical acrylic pressure-sensitive adhesive film comprising the cured product, and a touch screen panel and an optical element having the same. .

Rubber-based adhesives, acrylic adhesives, vinyl ether-based adhesives, silicone-based adhesives, and the like have been used as adhesives for optical components used in various optical devices. Among them, acrylic pressure-sensitive adhesives containing an acrylic polymer as a main component are used in various fields for the reason that they are excellent in weather resistance and oxidative deterioration. Adhesives for this purpose are usually referred to as optical adhesives or more specifically optically clear adhesives (OCA, Optical Clear Adhesive).

For example, the display is composed of a touch screen panel (TSP, Touch Screen Panel) and a liquid crystal module, and the touch screen panel has a laminated structure such as a conductive film and a transparent substrate. At this time, an adhesive is used when attaching each layer to form a laminated structure of the touch screen panel, and an adhesive is also used when attaching the touch screen panel and the liquid crystal module.

The adhesive applied to the touch screen panel should have excellent high-temperature, high-humidity reliability and good step absorption performance depending on the location of use. In particular, since touch sensitivity is very important for a touch screen panel, the use of an adhesive having a low dielectric constant is required for this purpose.

However, it is very difficult to develop an optical pressure-sensitive adhesive having all of the above-described physical properties at the same time.

Therefore, the problem according to one aspect to be solved by the present invention is that the dielectric constant is low, so touch sensitivity can be given, and the step absorption performance and high temperature and high humidity reliability are good, so that it can be usefully used as an adhesive film for an optical device such as a touch screen panel. To provide an acrylic pressure-sensitive adhesive composition.

In addition, an object according to another aspect to be solved by the present invention is to provide an acrylic pressure-sensitive adhesive film including a cured product of the above-described acrylic pressure-sensitive adhesive composition, and a touch screen panel and optical device having the same.

In order to solve the above technical problem, the acrylic pressure-sensitive adhesive composition according to the first embodiment of the present invention includes a polymerization unit made of fluorinated (meth)acrylate; and an acrylic copolymer including an alkyl (meth)acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms.

According to the second embodiment of the present invention, in the first embodiment, the polymerization unit made of the fluorinated (meth)acrylate may have an alkyl group or an alkoxy group having 3 to 15 fluorine atoms and 1 to 8 carbon atoms. More specifically, the polymerization unit made of fluorinated (meth)acrylate is 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 1,1,5- It may be at least one selected from the group consisting of octafluoropentyl acrylate and 1,1,2,2-tridecafluorooctyl acrylate.

According to a third embodiment of the present invention, in at least one embodiment of the first embodiment or the second embodiment, the content of the polymerization unit made of the fluorinated (meth)acrylate is based on the total weight of the acrylic copolymer. As may be 0.5 to 10% by weight.

According to a fourth embodiment of the present invention, in at least one embodiment of the first to third embodiments, the alkyl (meth)acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms is isodecyl. (meth)acrylate, isomyristyl (meth)acrylate, isostearyl (meth)acrylate, 2-propylheptyl (meth)acrylate, isoundecyl (meth)acrylate, isododecyl (meth)acrylic It may be any one or more selected from the group consisting of rate, isotridecyl (meth) acrylate, isopentadecyl (meth) acrylate, isohexadecyl (meth) acrylate, and isoheptadecyl (meth) acrylate.

According to a fifth embodiment of the present invention, in any one or more embodiments of the first to fourth embodiments, the content of the alkyl (meth)acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms is It may be 20 to 40% by weight based on the total weight of the acrylic copolymer.

According to a sixth embodiment of the present invention, in at least one embodiment of the first to fifth embodiments, the acrylic copolymer is an alkyl (meth)acrylate having a branched alkyl group having 1 to 22 carbon atoms; It may further include any one or more polymerization units selected from the group consisting of alkyl (meth) acrylate having a cycloalkyl group having 3 to 15 carbon atoms and (meth) acrylate having a hydroxyl group.

According to the seventh embodiment of the present invention, in at least one embodiment of the first to sixth embodiments, the acrylic copolymer may further include a photoreactive acrylic polymer unit.

The above-described acrylic pressure-sensitive adhesive composition may be cured to prepare an acrylic pressure-sensitive adhesive film for optical use, and the acrylic pressure-sensitive adhesive film for optical use may have a dielectric constant of 3.0 or less.

This optical acrylic pressure-sensitive adhesive film can be particularly usefully used for optical devices by directly attaching them between the touch screen panel and the liquid crystal module of the optical device.

In the acrylic pressure-sensitive adhesive composition of the present invention, the acrylic copolymer as a resin component includes a polymer unit made of fluorinated (meth)acrylate, thereby lowering the dielectric constant to provide touch sensitivity.

In addition, since the acrylic copolymer includes an alkyl (meth)acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms, softness is imparted to the adhesive film to ensure excellent step absorption and high temperature and high humidity reliability.

Hereinafter, the present invention will be described in detail. The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Hereinafter, an acrylic pressure-sensitive adhesive composition for optics according to the present invention will be described.

In the present invention, (meth)acrylate should be interpreted as meaning including both acrylates and methacrylates.

The acrylic pressure-sensitive adhesive composition according to the first embodiment of the present invention includes a polymerization unit made of fluorinated (meth)acrylate; and an acrylic copolymer including an alkyl (meth)acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms.

The polymer unit made of the fluorinated (meth)acrylate of the acrylic copolymer can provide touch sensitivity by lowering the dielectric constant when forming the adhesive film. The polymerization unit made of the fluorinated (meth)acrylate may have an alkyl group or an alkoxy group having 1 to 8 carbon atoms having 3 to 15 fluorine atoms. More specifically, the polymerization unit made of fluorinated (meth)acrylate is 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 1,1,5- It may be at least one selected from the group consisting of octafluoropentyl acrylate and 1,1,2,2-tridecafluorooctyl acrylate.

When the content of the polymerization unit made of fluorinated (meth)acrylate is 0.5 to 10% by weight based on the total weight of the acrylic copolymer, it is more advantageous to reduce the dielectric constant and secure reliability at high temperature and high humidity at the same time. More preferably, it is 1 to 6 weight%, Even more preferably, it is 1 to 2 weight%.

In addition, the alkyl (meth)acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms of the acrylic copolymer imparts softness to the adhesive film to ensure excellent step absorption and high temperature and high humidity reliability. The alkyl (meth) acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms is, for example, isodecyl (meth) acrylate, isomyristyl (meth) acrylate, isostearyl (meth) acrylate, 2- Propylheptyl (meth) acrylate, isoundecyl (meth) acrylate, isododecyl (meth) acrylate, isotridecyl (meth) acrylate, isopentadecyl (meth) acrylate, isohexadecyl (meth) It may be any one or more selected from the group consisting of acrylate and isoheptadecyl (meth) acrylate.

When the content of the alkyl (meth)acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms is 20 to 40 wt% based on the total weight of the acrylic copolymer, good step absorption and high temperature and high humidity reliability are ensured and low dielectric constant It is also beneficial to achieve

The acrylic copolymer having the above-described polymer units is an alkyl (meth)acrylate having a branched alkyl group having 1 to 22 carbon atoms, an alkyl (meth)acrylate having a cycloalkyl group having 3 to 15 carbon atoms, and (meth)acrylic having a hydroxyl group. It may further include any one or more polymerization units selected from the group consisting of rates.

Alkyl (meth) acrylate having a branched alkyl group having 1 to 22 carbon atoms is isopropyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, 2-ethylhexyl (meth) It may include one selected from the group consisting of acrylate, 2-ethylbutyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, and combinations thereof.

The alkyl (meth) acrylate having a cycloalkyl group having 3 to 15 carbon atoms may include isobornyl (meth) acrylate.

Additionally, in addition to the aforementioned alkyl (meth)acrylate polymerization unit, an alkyl (meth)acrylate having a linear alkyl group having 1 to 16 carbon atoms may be further included. For example, the alkyl (meth) acrylate having a linear alkyl group having 1 to 16 carbon atoms is methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) ) may include one selected from the group consisting of acrylate, pentyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, tetradecyl (meth) acrylate, and combinations thereof. .

These alkyl (meth) acrylate polymer units may contain from about 30 wt% to about 70 wt%, for example, from about 45 wt% to about 60 wt%, based on the weight of the acrylic copolymer species.

The (meth)acrylate having a hydroxyl group contributes to securing reliability by controlling the dielectric constant and improving adhesion performance and cohesive force at the same time.

As (meth)acrylate having a hydroxyl group, hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl ( Meth) acrylate, 10-hydroxydecyl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl (meth) acrylate, caprolactone-modified 2-hydroxyethyl (metal) acrylate, N-hydroxy Ethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-propyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 2-hydroxy It may include one selected from the group consisting of hydroxy-3-phenoxypropyl (meth) acrylate, 2,2-dimethyl-2-hydroxyethyl (meth) acrylate, and combinations thereof.

Instead of or in addition to (meth)acrylate having a hydroxyl group, a polymerization unit having a carboxyl group or a polymerization unit having a nitrogen-containing functional group may be further included. The (meth)acrylate polymerization unit having a hydroxyl group, the polymerization unit having a carboxyl group or the hydrophilic polymerization unit having a nitrogen-containing functional group may include, for example, from about 5% to about 30% by weight based on the weight of the acrylic copolymer species. have.

On the other hand, the acrylic copolymer having the above-described polymerization unit may further include a photoreactive acrylic polymerization unit for post-curing. The photoreactive acrylic polymer unit is an acrylic polymer unit capable of generating a photoactive reaction when irradiated with a predetermined amount of light, such as a benzophenone group, and may include, for example, benzophenone meta (acrylate), but is not limited thereto. The photoreactive acrylic polymer unit may include, for example, about 0.01 wt % to about 5 wt % based on the weight of the acrylic copolymer species.

The acrylic pressure-sensitive adhesive composition for optical use of the present invention may include about 0.01 to about 5 parts by weight of the photoinitiator based on 100 parts by weight of the acrylic air pressure body, for example, about 0.1 to about 1.0 parts by weight. Examples of photoinitiators include alpha-hydroxyketones initiators, phenylglyoxylates initiators, benzyldimethyl-ketals initiators, alpha-aminoketones initiators, monoacylphosphines initiators, bisacylphosphines initiators, phosphine oxides initiators, and metallo Senryu initiator, iodonium salt initiator, etc. can be illustrated.

The optical acrylic pressure-sensitive adhesive composition of the present invention may further include a curing agent, and in this case, 0.01 to 1 part by weight of a curing agent may be included with respect to 100 parts by weight of the acrylic copolymer to ensure an appropriate degree of curing.

In addition, the optical acrylic pressure-sensitive adhesive composition of the present invention is one selected from the group consisting of UV stabilizers, antioxidants, reinforcing agents, fillers, defoamers, surfactants, plasticizers, and combinations thereof in the range that does not affect the purpose of the present invention It may further include the above additives.

The present invention provides an acrylic pressure-sensitive adhesive film for optical use comprising a cured product of the above-described acrylic pressure-sensitive adhesive composition. In this case, the dielectric constant of the adhesive film may be 3.0 or less. Here, the dielectric constant means the dielectric constant measured at a frequency of 100 kHz.

The optical acrylic pressure-sensitive adhesive film of the present invention is a layer formed to have adhesiveness by partially curing the above-described acrylic pressure-sensitive adhesive composition, or it is meant to include all adhesive films obtained by additional curing and curing.

This optical acrylic pressure-sensitive adhesive film can be particularly usefully used for optical devices by directly attaching them between the touch screen panel and the liquid crystal module of the optical device.

Hereinafter, examples will be given to describe the present invention in detail. However, the embodiment according to the present invention may be modified in various other forms, and the scope of the present invention should not be construed as being limited to the embodiment described in detail below. The embodiments of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art.

Preparation of acrylic pressure-sensitive adhesive composition

Examples and Comparative Examples

2-ethylhexyl acrylate (EHA), isobornyl acrylate (IBOA), isostearyl acrylate (ISTA), hydroxyethyl acrylate (HEA), fluorinated acrylates and benzophenone methacrylates (BPMA) Synthesizing an acrylic copolymer polymerized from the mixed monomer components included in the content shown in Table 1, mixing 0.01 parts by weight of 1,6-hexanediol diacrylate (HDDA) as a curing agent with respect to 100 parts by weight of the acrylic copolymer, and a photoinitiator A photocurable adhesive composition was prepared by mixing 0.3 parts by weight of a benzyldimethyl-ketal initiator as (PI). At this time, the amount of light to initiate the photoreaction of the benzophenone methacrylate (BPMA) is 3J/cm 2 , and the light amount to initiate the photoreaction of the photoinitiator is 0.9J/cm 2 .

Example EHA IBOA ISTA HBA Fluorinated acrylates BPMA (parts by weight) (parts by weight) (parts by weight) (parts by weight) (parts by weight) (parts by weight) Kinds (parts by weight) One 49 25 14.8 10 2,2,2-trifluoroethyl acrylate One 0.2 2 48 25 14.8 10 2,2,2-trifluoroethyl acrylate 2 0.2 3 49 25 14.8 10 2,2,3,3-tetrafluoropropyl acrylate One 0.2 4 48 25 14.8 10 2,2,3,3-tetrafluoropropyl acrylate 2 0.2 5 49 25 14.8 10 1,1,5-octafluoropentyl acrylate One 0.2 6 48 25 14.8 10 1,1,5-octafluoropentyl acrylate 2 0.2 7 49 25 14.8 10 1,1,2,2-tridecafluorooctyl acrylate One 0.2 8 48 25 14.8 10 1,1,2,2-tridecafluorooctyl acrylate 2 0.2 9 46 25 14.8 10 1,1,2,2-tridecafluorooctyl acrylate 4 0.2 10 44 25 14.8 10 1,1,2,2-tridecafluorooctyl acrylate 6 0.2 comparative example EHA IBOA ISTA HBA Fluorinated acrylates BPMA (parts by weight) (parts by weight) (parts by weight) (parts by weight) (parts by weight) (parts by weight) Kinds (parts by weight) One 40 30 15 15 - 0 - 2 50 30 - 20 - 0 - 3 50 30 - 19.2 - 0 0.2

Manufacture and evaluation of acrylic adhesive film

A partially cured product was prepared by photocuring the pressure-sensitive adhesive compositions of Examples and Comparative Examples with a light amount of 1 J/cm 2 , and a fully cured product was prepared by irradiating the partially cured product with a light amount of 3 J/cm 2 . The same amount of each of the partially cured product and the fully cured product was left for 24 hours after immersion in ethyl acetate solution, and then dried. By measuring the ratio of the weight, the degree of curing (%) was derived. The results are shown in Table 2 below.

<Evaluation of dielectric constant>

By using a dielectric constant measuring device (Agilent, E4980A LCR meter + 16451B dielectric test fixture device), the dielectric constant of each of the examples and comparative examples was measured at a frequency of 100 kHz. The dielectric constant of each partially cured product was the same as that of each fully cured product. The results are shown in Table 2 below.

<Evaluation of step absorbency>

For each of the partially cured products of Examples and Comparative Examples, the step absorbency (%) according to Equation 1 was measured, and the step absorbency was evaluated according to the following criteria.

Equation 1

Step Absorbency (%) = (Maximum Step Absorbable/Total Thickness of Adhesive Film) × 100

◎: more than 15%

○: 10~15%

X: 5% or less

The above evaluation results are shown in Table 2 below.

<Evaluation of reliability in high-temperature, high-humidity environment>

For each fully cured product of Examples and Comparative Examples, the occurrence of bubbles and cloudiness after standing for 240 hours under a high temperature of 85° C. and a relative humidity of 85% was measured, and the results are shown in Table 2 below.

Hardening (%) permittivity step absorbency High temperature and humidity reliability partially cured product fully cured product 100 kHz (%) bubble generation cloudiness Example 1 53 74 2.89 ◎ X X Example 2 55 78 2.90 ◎ X X Example 3 62 81 2.95 ◎ X X Example 4 58 79 2.90 ◎ X X Example 5 63 83 2.94 ◎ X X Example 6 51 81 2.89 ◎ X X Example 7 59 79 2.84 ◎ X X Example 8 57 80 2.87 ○ X X Example 9 59 80 2.74 ○ X X Example 10 64 83 2.62 ○ X X Comparative Example 1 18 19 3.17 ○ ○ X Comparative Example 2 21 21 4.32 ○ X X Comparative Example 3 56 69 4.18 ○ X X

Referring to the results of Table 2, it can be said that, unlike the comparative examples, the acrylic adhesive films according to Examples have very good properties of dielectric constant, step absorption, and high temperature, high humidity reliability.

Claims (12)

a polymerization unit made of fluorinated (meth)acrylate; and
An acrylic pressure-sensitive adhesive composition for optical use comprising an acrylic copolymer comprising an alkyl (meth)acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms. According to claim 1,
The polymerization unit made of the fluorinated (meth)acrylate is an acrylic pressure-sensitive adhesive composition for optical use, characterized in that it has an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 3 to 15 fluorine atoms. According to claim 1,
The polymerization unit made of the fluorinated (meth)acrylate is 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 1,1,5-octafluoropentyl An acrylic pressure-sensitive adhesive composition for optical use, characterized in that at least one selected from the group consisting of acrylate and 1,1,2,2-tridecafluorooctyl acrylate. According to claim 1,
The content of the polymer unit made of the fluorinated (meth) acrylate is an acrylic pressure-sensitive adhesive composition for optical use, characterized in that 0.5 to 10% by weight based on the total weight of the acrylic copolymer. According to claim 1,
The alkyl (meth) acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms is isodecyl (meth) acrylate, isomyristyl (meth) acrylate, isostearyl (meth) acrylate, 2-propylheptyl (meth) acrylate, isoundecyl (meth) acrylate, isododecyl (meth) acrylate, isotridecyl (meth) acrylate, isopentadecyl (meth) acrylate, isohexadecyl (meth) acrylate And an acrylic pressure-sensitive adhesive composition for optical, characterized in that at least one selected from the group consisting of isoheptadecyl (meth) acrylate. According to claim 1,
The content of the alkyl (meth)acrylate polymerization unit having a branched alkyl group having 10 to 25 carbon atoms is 20 to 40 wt% based on the total weight of the acrylic copolymer. According to claim 1,
The acrylic copolymer is an alkyl (meth) acrylate having a branched alkyl group having 1 to 22 carbon atoms, an alkyl (meth) acrylate having a cycloalkyl group having 3 to 15 carbon atoms, and (meth) acrylate having a hydroxyl group. An acrylic pressure-sensitive adhesive composition for optical use, characterized in that it further comprises one or more selected polymerization units. According to claim 1,
The acrylic copolymer is an acrylic pressure-sensitive adhesive composition for optical use, characterized in that it further comprises a photoreactive acrylic polymer unit. An acrylic adhesive film for optical use comprising a cured product of the acrylic adhesive composition of any one of claims 1 to 8. 10. The method of claim 9,
The acrylic adhesive film for optical use has a dielectric constant of 3.0 or less. A touch screen panel having the optical acrylic adhesive film of claim 9 . An optical device having the touch screen panel of claim 11 .