KR20140139893A - Pressure-Sensitive Adhesive Composition and Pressure-Sensitive Adhesive film for Touch Screen Panel Using the Same - Google Patents

Abstract

In the present invention, provided are an adhesive resin composition for touchscreen panels and an adhesive film using the same, wherein the adhesive resin composition for touchscreen panels have outstanding adhesion for various substrates, good transparency and durability, heat resistance and cuttability and prevent loosening, delamination, the bending of panels and curl caused by bubbles. More specifically, in the present invention, provided is an adhesive resin composition for touchscreen panels and an adhesive film using the same, wherein the adhesive resin composition for touchscreen panels has an outstanding physical property to prevent the loosening, the delamination, the bending of panels and the curl by controlling the degree of cross-linking and cohesive force with use of an adhesive composition including copolymerization photoinitiators having a copolymerization functional group or the double bonding of carbon and carbon in molecules.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive composition for a touch screen panel,

The present invention relates to a pressure-sensitive adhesive resin composition for a touch screen panel and an adhesive film using the same. More specifically, the present invention relates to the production of an adhesive film using a pressure-sensitive adhesive resin composition comprising a copolymerizable photoinitiator having a copolymerizable functional group (carbon-carbon double bond) in a molecular structure, And is characterized by providing excellent physical properties such as durability, heat resistance, warpage of the panel, curl suppression and the like.

In recent years, the market for portable handsets is growing rapidly, especially for smartphones and tablet PCs. A feature of such an electronic device is that it has means for providing an input device to a user interacting intuitively at the same time as an image display device for displaying information. For this purpose, a touch panel display device in which a touch panel is coupled to a display portion is adopted in most portable electronic devices. 1, which is a schematic cross-sectional view showing an example of a conventional touch panel display device, a glass or plastic substrate 1 on which an ITO conductive layer is coated via a visibility resin layer 2 on a plastic substrate 3 of a liquid crystal display device, As shown in FIG.

Such a touch panel display device is generally composed of a glass or plastic panel and an LCD module. For a display device having a touch function, a touch sensor is included. Depending on the implementation method of the sensor, a resistance film type, Method, and an ultrasonic method.

Basically, the touch panel is composed of two conductive ITO (Indium Tin Oxide) layers. In the electrostatic capacity type, the signal is detected by electromagnetic change instead of physical contact between the upper and lower electrodes. Of the touch screen panel is mainly used, but now the capacitive method is adopted at a fast reaction rate.

Typically, members used in a touch panel, for example, a cover glass or a plastic substrate, a conductive film, a triacetylcellulose (TAC) sheet used for a polarizing plate of an LCD module, and the like are bonded using a transparent adhesive film. At this time, the heterogeneous surfaces of the bonded body are not necessarily flat but may have irregularities. For example, in the case of an ITO conductive film, a step is generated due to patterned ITO. Therefore, the transparent pressure-sensitive adhesive film needs to have a step-gap fillability capable of releasing the stepwise gap. Further, in the step of bonding different kinds of optical members, there is a case where heating or pressurizing treatment is applied after bonding the optical members. Bubbles are generated by gases, solvents, low molecular weight monomers and additives, A phenomenon may occur. Further, due to the difference in thermal expansion and shrinkage ratio between the optical members, warping or curling of the panel may occur. In order to solve this problem, it is necessary to sufficiently remove the residual monomer or solvent before the bonding process, and the cohesive force and viscoelasticity of the pressure-sensitive adhesive composition are controlled so as to prevent warping and curling of the panel. A pressure sensitive adhesive composition having low cohesion or viscoelasticity may be used to prevent warping or curling of the panel during heat treatment. However, in order to adjust the size of the touch panel member, Problems often arise.

Korean Patent Laid-open Nos. 10-2006-0043847 and 10-2012-0113696 disclose a pressure-sensitive adhesive composition comprising an acryl-based polymer having a weight average molecular weight different from that of the pressure-sensitive adhesive composition (a mixture of a high molecular weight polymer and a low molecular weight polymer) Lt; / RTI > However, the pressure-sensitive adhesive composition in the above literature has a problem that the heat resistance is low in a high-temperature process owing to the use of a polymer having a low molecular weight, which easily causes warping, lifting or curling of the panel.

An object of the present invention is to provide an adhesive resin composition and an adhesive film which are optimized in consideration of the above problems.

Korean Patent Publication No. 10-2006-0043847 Korean Patent Publication No. 10-2012-0113696

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a heat- curl), and a pressure-sensitive adhesive film using the pressure-sensitive adhesive composition.

These and other objects and advantages of the present invention will become more apparent from the following description of a preferred embodiment thereof.

The above object is achieved by a pressure-sensitive adhesive resin composition for a touch screen panel, which comprises a transparent pressure-sensitive adhesive resin and a copolymerizable photoinitiator having a carbon-carbon double bond-containing functional group in a molecular structure.

Here, the transparent pressure-sensitive adhesive resin is a heat, ultraviolet or heat and ultraviolet ray curable resin, and has a weight average molecular weight of 500,000 to 2,000,000.

Preferably, the copolymerizable photoinitiator is selected from the group consisting of phenyl- (1-acryloyloxy) -cyclohexylketone, 2-hydroxy-1- [4- (2- acryloyloxyethoxy) At least one selected from the group consisting of 4-acryloyloxybenzophenone,? -Arylbenzoin, 4-acrylamidocarbonyldioxybenzophenone, p-vinylbenzophenone and 4-benzophenylvinylcarbonate Is a copolymerizable photoinitiator.

Preferably, the pressure-sensitive adhesive resin composition has a viscosity at 25 DEG C of 1,000 cps to 6,000 cps.

Preferably, the copolymerizable photoinitiator comprises 0.1 to 10 parts by weight based on 100 parts by weight of the transparent pressure-sensitive adhesive resin.

The above object is also achieved by an optical adhesive film comprising a base film and a pressure-sensitive adhesive layer coated on at least one side of the base film with a pressure-sensitive adhesive resin composition for a touch screen panel having the above-described optical properties .

Here, the thickness of the pressure-sensitive adhesive layer is 30 to 200 mu m.

Preferably, the pressure-sensitive adhesive film has a peeling speed of 300 mm / min and a 180-degree peel force with respect to the substrate at a room temperature of 1,000 to 4,000 gf / in.

Preferably, the adhesive film has a haze of 5% or less and a total light transmittance of 90% or more.

The above object can be attained by a touch panel display device in which the pressure sensitive adhesive layer of the optical pressure sensitive adhesive film described above is bonded to a display device module and the optical pressure sensitive adhesive film is adhered to a touch panel to fix the touch panel to the display device module Lt; / RTI >

According to the present invention, it is possible to provide a resin composition which has excellent adhesiveness to various substrates, excellent transparency and durability, and particularly a transparent adhesive resin and a copolymerizable photoinitiator having a copolymerizable functional group (carbon-carbon double bond) It is excellent in properties such as heat resistance, warping of the panel, curl suppression and the like.

1 is a schematic cross-sectional view showing an example of a conventional touch panel display device.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. It will be apparent to those skilled in the art that these embodiments are provided by way of illustration only for the purpose of more particularly illustrating the present invention and that the scope of the present invention is not limited by these embodiments .

The present invention solves the problems of the prior art by controlling the degree of crosslinking and cohesion of an adhesive film produced using a pressure-sensitive adhesive composition comprising a copolymerizable photoinitiator having a copolymerizable functional group (carbon-carbon double bond) in a molecular structure Sensitive adhesive composition for a touch screen and an adhesive film having excellent physical properties. More particularly, the present invention relates to a pressure-sensitive adhesive resin composition for a touch screen panel, which comprises a copolymerizable photoinitiator having a carbon-carbon double bond-containing functional group in a molecular structure in a transparent pressure-sensitive adhesive resin constituting the pressure- .

The present invention provides, as means for solving the above problems, a high molecular weight transparent acrylic polymer resin; Refers to a pressure-sensitive adhesive resin composition for a touch panel polymerized through a copolymerizable photoinitiator having a copolymerizable functional group (carbon-carbon double bond) in a molecular structure and an adhesive film produced therefrom.

The copolymerizable photoinitiator contained in the pressure-sensitive adhesive resin composition for a touch screen panel according to the present invention includes a copolymerizable functional group (carbon-carbon double bond) capable of reacting with a resin composition in a molecular structure and a molecular structure capable of forming a radical by ultraviolet . When the above-mentioned copolymerizable photoinitiator having a copolymerizable functional group is used, physical properties such as adhesion, cohesion, durability and heat resistance of the adhesive resin composition may be affected. When the amount of the above-mentioned copolymerizable photoinitiator is increased, the cohesive force of the adhesive resin composition is increased, and durability and heat resistance can be improved. However, when the amount is increased, the cohesive force is too high, so that the adhesive strength and the like may be lowered. On the contrary, when the amount of the used amount is decreased, the cohesive force is lowered and the effect of improving the filling property of the step of the patterned ITO conductive film can be obtained. However, in the punching process for adjusting the size of the member in the optical member process, And the like.

The copolymerizable photoinitiator used in the present invention has a copolymerizable functional group (carbon-carbon double bond) in the molecular structure and is particularly suitable for use when the adhesive strength, durability, heat resistance and workability of the final resin composition can be controlled at a harmful level Not limited.

Examples of the copolymerizable photoinitiator containing the copolymerizable functional group (carbon-carbon double bond) in the molecular structure include phenyl- (1-acryloyloxy) -cyclohexylketone, 2- hydroxy- 1- [4- (2- Acryloyloxyethoxy) phenyl] -2-methyl-1-propanone, 4-acryloyoxybenzophenone,? -Arylbenzoin, 4-acrylamidocarbonyldioxybenzophenone, p- Phenol, 4-benzophenyl vinyl carbonate, and the like, but not limited thereto.

The copolymerizable photoinitiator may be included in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the transparent pressure-sensitive adhesive resin. When the content is less than 0.1 part by weight, the effect of improving the cohesive strength of the resin composition may be insignificant, and in the punching work for adjusting the size of the member in the optical member process, there may occur processing problems such as adhesion of the pressure- If it exceeds 10 parts by weight, the cohesive force of the resin composition may be greatly increased and the adhesive strength may be lowered.

The transparent pressure-sensitive adhesive resin used in the present invention is a transparent acrylic polymer resin having a high molecular weight, and one side of the pressure-sensitive adhesive film made of a pressure-sensitive adhesive resin composition comprising a copolymerizable photoinitiator having a copolymerizable functional group (carbon-carbon double bond) Peel strength of 1,000 to 4,000 gf / in at a peeling speed of 300 mm / min and a 180-degree peel force on the substrate at room temperature after adhesion to the substrate.

The transparent pressure-sensitive adhesive resin may be at least one selected from the group consisting of methyl methacrylate, urethane acrylate, epoxy acrylate, silicone acrylate, ethylhexyl acrylate, butyl acrylate, ethyl acrylate, isobornyl acrylate, cyclohexyl methacrylate, glycidyl methacrylate Acrylate, glycidyl acrylate, behenyl acrylate, ethyl acrylate, lauryl acrylate, stearyl acrylate, acrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, phenox Acrylates having one or more double bonds in a molecular structure such as acrylic acid, methacrylic acid, methacrylic acid, methacrylic acid, methacrylic acid, methacrylic acid, methacrylic acid, Indication sheet as resin Of long as it has transparency which does not hinder the visibility it can be appropriately selected.

Also, a multi-functional crosslinking agent can be used together for the cohesive force and durability of the adhesive layer. As such a polyfunctional crosslinking agent, hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, diethylene glycol diacrylate And polyfunctional acrylic monomers such as bifunctional acrylic monomer, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, and trimethylpropane triacrylate. These may be used singly or in combination of two or more, but are not particularly limited thereto.

The transparent pressure-sensitive adhesive resin (transparent resin) is a heat, ultraviolet or heat / ultraviolet ray curable resin, and the molecular weight is not particularly limited as long as it does not impair transparency and workability. The acrylic polymer resin composition preferably has a molecular weight of 500,000 to 2,000,000.

In addition to the transparent resin and the photo-acidity photo-initiator, other additives such as a resin, a thermal polymerization initiator, an ultraviolet absorber, a defoaming agent, and a dispersant may be used in the adhesive resin composition insofar as they do not impair the adhesive strength, durability and optical properties.

The material used for the substrate sheet layer of the present invention may be any resin material used in a known plastic substrate sheet layer without any particular limitation, but is preferably an ester, ethylene, propylene, diacetate, triacetate, styrene, A polymer or a copolymer polymer having one structural unit selected from the group consisting of pentene, sulfone, ether ethyl ketone, imide, fluorine, nylon, acrylate, and alicyclic olefin series is used.

More preferably an ester type such as polyethylene terephthalate (PET) or the like, an acetate type such as triacetylcellulose (TAC), and an acrylate type such as polymethyl methacrylate (PMMA), which is excellent in transparency, strength and thickness uniformity A polymer or a copolymer polymer having one selected as a constitutional unit is used. In particular, a polymer having an ester system as a structural unit is used in terms of transparency, haze value, and mechanical properties.

The production process of the pressure-sensitive adhesive film using the pressure-sensitive adhesive resin composition and the base sheet can be used according to a conventional method for producing an adhesive film. The composition may have a viscosity at 25 DEG C of from 1,000 cps to 6,000 cps, preferably from 1,500 cps to 3,000 cps. By controlling the viscosity of the composition within the above range, process efficiency and physical properties after curing can be effectively maintained. When the viscosity of the composition is less than 1,000 cps, the coating property is good but it may not be easy to form a thick film. When the viscosity exceeds 6,000 cps, the applicability of the pressure-sensitive adhesive is poor and it is difficult to form a uniform film.

The thickness of the pressure-sensitive adhesive layer may be 30 to 200 占 퐉, preferably 50 to 150 占 퐉. When the thickness of the pressure-sensitive adhesive layer is less than 30 m, it is difficult to fill the air gap between the pressure-sensitive adhesive film and the substrate. When the thickness exceeds 200 m, the possibility of inflow of air bubbles and foreign substances into the pressure-

The adhesive film has a haze of 5% or less and a total light transmittance of 90% or more. Further, the bending characteristic of the adhesive film according to the present invention is characterized in that the degree of bending is less than 5 mm as compared with the reference plane.

The touch panel display device according to the present invention is characterized in that the pressure sensitive adhesive layer of the above-mentioned optical pressure sensitive adhesive film is bonded to a display device module, and the optical pressure sensitive adhesive film is adhered to the touch panel to fix the touch panel to the display device module do.

Hereinafter, the structure and effect of the present invention will be described in more detail with reference to examples and comparative examples. However, this embodiment is intended to explain the present invention more specifically, and the scope of the present invention is not limited to these embodiments.

[Example]

≪ Example 1 >

To prepare a transparent pressure-sensitive adhesive resin, 55 parts by weight of 2-ethylhexyl acrylate (2-EHA) was added to a reactor in which nitrogen gas was refluxed and temperature was controllable. 15 parts by weight of isobornyl acrylate (IBOA); And 30 parts by weight of hydroxyethyl acrylate (HEA) were added, and 1 part by weight of 4-acryloyloxybenzophenone (4-ABP) (Chemitech GmbH) as a copolymerization photoinitiator was added thereto, followed by photopolymerization for 5 minutes. The reaction was terminated by partial polymerization to obtain a resin syrup having a viscosity of 2,000 cps. The weight average molecular weight of the partially polymerized transparent acrylic resin is 800,000. The prepared coating solution was coated on a 75 탆 thick polyethylene terephthalate (PET) film having a thickness of 100 탆 and then irradiated for 5 minutes using a UV curing machine to prepare a cured adhesive film.

≪ Example 2 >

A partially-polymerized transparent acrylic resin was obtained in the same manner as in Example 1 except that 4-acrylamidocarbonyldioxybenzophenone (4-ACDB) was used as the copolymerizable photoinitiator. The partially polymerized transparent acrylic resin has a weight average molecular weight of 800,000 and a viscosity of 2,000 cps. An adhesive film was prepared in the same manner as in Example 1 using the prepared coating solution.

≪ Example 3 >

In Example 1, a partially-polymerized transparent acrylic resin was obtained in the same manner, except that phenyl- (1-acryloyloxy) -cyclohexylketone (PAC) was used as the copolymerizable photoinitiator. The partially polymerized transparent acrylic resin had a weight average molecular weight of 85,000 and a viscosity of 2,300 cps. An adhesive film was prepared in the same manner as in Example 1 using the prepared coating solution.

<Example 4>

0.2 part by weight of polyfunctional hexane diol diacrylate (HDDA) was further added to the partially polymerized transparent acrylic resin composition obtained in Example 1 to obtain a final resin composition. An adhesive film was prepared in the same manner as in Example 1 using the prepared coating solution.

[Comparative Example]

&Lt; Comparative Example 1 &

A transparent acrylic adhesive resin was obtained in the same manner as in Example 1 except that the initiator was heat-polymerized using 1 part by weight of azobisisobutyronitrile (AIBN). The viscosity of the polymerized resin composition is 1,800 cps and the weight average molecular weight is 700,000. An adhesive film was prepared in the same manner as in Example 1 using the prepared coating solution.

&Lt; Comparative Example 2 &

To the partially polymerized transparent acrylic resin composition obtained in Comparative Example 1, 0.2 part by weight of polyfunctional hexanediol diacrylate (HDDA) was further added. An adhesive film was prepared in the same manner as in Example 1 using the prepared coating solution.

&Lt; Comparative Example 3 &

A pressure-sensitive adhesive film was prepared in the same manner as in Comparative Example 1, except that 1 part by weight of the copolymerizable photoinitiator 4-acryloyloxybenzophenone (4-ABP) was further added. The viscosity of the polymerized resin composition is 1,900 cps and the weight average molecular weight is 750,000.

&Lt; Comparative Example 4 &

A pressure-sensitive adhesive film was prepared in the same manner as in Comparative Example 2, except that 1 part by weight of the copolymerizable photoinitiator 4-acryloyloxybenzophenone (4-ABP) was further added. The viscosity of the polymerized resin composition is 1,900 cps and the weight average molecular weight is 750,000.

The properties of the adhesive films according to Examples 1 to 4 and Comparative Examples 1 to 4 were measured through the following experimental examples, and the results are shown in Table 1 below.

[Experimental Example]

1. Peeling force measurement

One side of the pressure-sensitive adhesive film made of a pressure-sensitive adhesive resin composition was attached to the SUS surface, and the pressure-sensitive adhesive sheet was laminated at a weight of 2 kgf / cm ² and left for 30 minutes. The peel strength was measured at a peeling speed of 300 mm / min and a substrate at 180 deg.

2. Total light transmittance and haze measurement

The total light transmittance and haze of the adhesive film were measured using a spectrophotometer (Model NDH2000, manufactured by Nippon Denshoku Co., Ltd.).

3. Evaluation of bending characteristics

One side of the adhesive film was attached to one side of a plastic composite sheet (thickness: 1 mm, Mitsubishi Gas Chemical). A PET film having an ITO layer formed thereon was adhered to the other side of the adhesive film and pressed to produce a sample. The fabricated specimens were allowed to stand in an oven at 140 ° C for 72 hours, and their degree of warpage was compared.

4. Evaluation of durability

A specimen was attached to a TAC (triacetyl cellulose) film on one side of a pressure-sensitive adhesive film made of a pressure-sensitive adhesive resin composition and attached to a plastic film coated with ITO conductive layer on the other side. The specimens were allowed to stand for 5 days in a thermostatic hygrostat at 90 ° C and 90% relative humidity, and durability was evaluated by observing the occurrence of bubbling, lifting or peeling.

(Evaluation criteria for durability)

○: No occurrence of lifting, peeling or air bubbles

△: Small amount of lifting, peeling or bubble generation

X: There is a lot of lifting, peeling or bubbling

Peel force
(gf / in) Transmittance
(%) Hayes
(%) Degree of bending
(mm) durability Example 1 2890 92.5 0.6 1. 7 ○ Example 2 2750 92.7 0.5 2.0 ○ Example 3 2530 91.7 0. 8 2.2 ○ Example 4 1520 90.6 1.2 4.2 ○ Comparative Example 1 3240 93.5 0.4 1.8 △ Comparative Example 2 1250 92.1 0.8 6.0 △ Comparative Example 3 2350 90.5 1.6 3.0 △ Comparative Example 4 890 89.5 2.5 8.2 X

As can be seen in Table 1, in Examples 1 to 3, no significant difference was observed in peel strength, optical characteristics, warpage, and durability due to the difference of the copolymerizable photoinitiators. However, in the case of Example 4, as compared with Example 1, it can be seen that the peeling force is decreased and the degree of warpage is different due to the effect of the crosslinking agent, but it is a good level. On the other hand, in Comparative Examples 1 to 4 using a thermal polymerization initiator, there was a problem of lifting, peeling and bubble generation at the interface between optical members under severe conditions of high temperature and high humidity. As a result, it can be seen that the physical properties of the entire acrylic transparent resin can be controlled by controlling the photo-synthetic photoinitiator.

It is to be understood that the present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention.

1: glass or plastic substrate coated with ITO conductive layer
2:
3: Plastic substrate of liquid crystal display

Claims (10)

A pressure-sensitive adhesive resin, and a copolymerizable photoinitiator having a carbon-carbon double bond-containing functional group in a molecular structure. The method according to claim 1,
Wherein the transparent pressure-sensitive adhesive resin is a heat, ultraviolet or heat and ultraviolet ray-curable resin having a weight average molecular weight of 500,000 to 2,000,000. The method according to claim 1,
The copolymerizable photoinitiator may be selected from the group consisting of phenyl- (1-acryloyloxy) -cyclohexylketone, 2-hydroxy-1- [4- (2- acryloyloxyethoxy) phenyl] At least one copolymerizable photoinitiator selected from the group consisting of 4-acryloyloxybenzophenone,? -Arylbenzoin, 4-acrylamidocarbonyl dioxybenzophenone, p-vinylbenzophenone and 4-benzophenyl vinyl carbonate Wherein the pressure-sensitive adhesive resin composition is a pressure-sensitive adhesive resin composition for a touch screen panel. The method according to claim 1,
Wherein the pressure-sensitive adhesive resin composition has a viscosity at 25 DEG C of 1,000 cps to 6,000 cps. The method according to claim 1,
Wherein the copolymerizable photoinitiator comprises 0.1 to 10 parts by weight based on 100 parts by weight of the transparent pressure-sensitive adhesive resin. Characterized in that it comprises a base film and a pressure-sensitive adhesive layer applied on at least one side of the base film with the pressure-sensitive adhesive resin composition for a touch screen panel having the improved optical properties according to any one of claims 1 to 5. [ Optical adhesive film. The method according to claim 6,
Wherein the pressure-sensitive adhesive layer has a thickness of 30 to 200 占 퐉. The method according to claim 6,
Wherein the adhesive film has a peeling speed of 300 mm / min and a 180-degree peel force on the substrate at a room temperature of 1,000 to 4,000 gf / in. 9. The method according to any one of claims 6 to 8,
Wherein the pressure-sensitive adhesive film has a haze of 5% or less and a total light transmittance of 90% or more. The touch panel display device according to claim 9, wherein the adhesive layer of the optical adhesive film according to claim 9 is attached to the display device module, and the optical adhesive film is adhered to the touch panel to fix the touch panel to the display device module.

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