Pressure-Sensitive Adhesive Composition

Abstract

The present application relates to a pressure-sensitive adhesive composition and a use thereof. The polarizing plate to which the pressure-sensitive adhesive composition of the present application is applied has an advantage that the performance capable of blocking the blue light, for example, the light having a wavelength region of 380 nm or more, is particularly excellent, when attached to an organic light emitting panel, especially, an organic light emitting panel comprising a plastic substrate.

Claims

1. A pressure-sensitive adhesive composition comprising a pressure-sensitive adhesive polymer and an ultraviolet absorber which is a compound of the following formula 1: ##STR00005## wherein, X.sub.1 and R.sub.1 to R.sub.4 are each independently a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group or an alkoxycarbonyl group, and L is a single bond, alkylene, alkenylene, alkynylene, COO or OCO.

2. The pressure-sensitive adhesive composition according to claim 1, wherein L in Formula 1 is a single bond or an alkylene group, X.sub.1 is a hydrogen atom or an alkyl group, R.sub.1 or R.sub.2 is an alkyl group or an alkoxy group, and R.sub.3 or R.sub.4 is an alkyl group, an alkenyl group or an alkynyl group.

3. The pressure-sensitive adhesive composition according to claim 1, wherein L in Formula 1 is a single bond or an alkylene group having 1 to 4 carbon atoms, X.sub.1 is a hydrogen atom, R.sub.1 or R.sub.2 is an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, R.sub.3 and R.sub.4 are each independently an alkyl group having 4 to 12 carbon atoms (provided that when any one of R.sub.1 and R.sub.2 is an alkyl group having 1 to 4 carbon atoms, the other is an alkoxy group having 1 to 4 carbon atoms).

4. The pressure-sensitive adhesive composition according to claim 1, wherein the maximum absorption wavelength of the ultraviolet absorber is in a range of 380 nm to 410 nm.

5. The pressure-sensitive adhesive composition according to claim 1, wherein the half-value width of the ultraviolet absorber at the maximum absorption wavelength is in a range of 10 nm to 60 nm.

6. The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive polymer comprises a polymerization unit of an alkyl (meth)acrylate monomer.

7. The pressure-sensitive adhesive composition according to claim 6, wherein the pressure-sensitive adhesive polymer further comprises a polymerization unit of a copolymerizable monomer having a polar functional group.

8. The pressure-sensitive adhesive composition according to claim 1, comprising the ultraviolet absorber in a ratio of 0.01 parts by weight to 10 parts by weight relative to 100 parts by weight of the pressure-sensitive adhesive polymer.

9. The pressure-sensitive adhesive composition according to claim 1, further comprising a crosslinking agent.

10. A polarizing plate comprising a polarizer and a pressure-sensitive adhesive layer formed on at least one side of the polarizer, wherein the pressure-sensitive adhesive layer is a cured product of the pressure-sensitive adhesive composition of claim 1.

11. The polarizing plate according to claim 10, wherein the polarizing plate has transmittance of 0.6% or less for light having a wavelength of 380 nm or more to 400 nm or less, and transmittance of less than 20% for light having a wavelength of more than 400 nm to 410 nm or less.

12. The polarizing plate according to claim 10, wherein the polarizing plate has a b value of 9.5 or less in CIE Lab color coordinates.

13. An organic light emitting device comprising an organic light emitting panel and the polarizing plate of claim 10.

14. The organic light emitting device according to claim 13, wherein the organic light emitting panel comprises a plastic substrate, a first electrode layer, an organic light emitting layer and a second electrode layer in this order, and the polarizing plate is attached to the side where the light is emitted from the organic light emitting panel via the pressure-sensitive adhesive layer.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0111] FIGS. 1 to 6 are diagrams illustratively showing structures of polarizing plates.

[0112] FIG. 7 is a diagram illustratively showing a structure of an organic light emitting device.

BEST MODE

[0113] Hereinafter, the present application will be described in more detail by way of examples, but the scope of the present application is not limited to the following examples.

Example 1

[0114] Preparation of Pressure-Sensitive Adhesive Composition

[0115] To a 1 L reactor with refluxing nitrogen gas and equipped with a cooling device so as to easily adjust a temperature, n-butyl acrylate (n-BA) and 4-hydroxybutyl acrylate (4-HBA) were introduced in a weight ratio of 99:1 (n-BA: 4-HBA). Subsequently, ethyl acetate (EAc) as a solvent was introduced to the reactor in a ratio of 180 parts by weight relative to 100 parts by weight of the sum of n-butyl acrylate and 4-hydroxybutyl acrylate, and nitrogen gas was purged for 60 minutes for oxygen removal. Thereafter, while maintaining the temperature at 67 C., AIBN (azobisisobutyronitrile) as a reaction initiator was introduced in an amount of 0.05 parts by weight relative to 100 parts by weight of the sum of n-butyl acrylate and 4-hydroxybutyl acrylate, followed by reaction for 8 hours. After the reaction, the reaction product was diluted with ethyl acetate to obtain an acrylic polymer having a solid content concentration of 30 wt % and a weight average molecular weight of 1,000,000.

[0116] About 4 parts by weight of an ultraviolet absorber (FDB-009, manufactured by Yamada, maximum absorption wavelength: about 394 nm) having the following formula A and about 0.1 parts by weight of a crosslinking agent (XDI-based isocyanate compound, T-39M manufactured by Mitsui chemicals) were formulated relative to 100 parts by weight of the solid content of the acrylic polymer to prepare a pressure-sensitive adhesive composition.

##STR00002##

[0117] Production of Pressure-Sensitive Adhesive Layer

[0118] The pressure-sensitive adhesive composition was coated on a release-treated surface of a release-treated PET (poly(ethylene terephthalate)) film (thickness: 38 m, MRF-38, manufactured by Mitsubishi) to have a thickness of about 10 m or so after drying, and heat-cured in an oven at 80 C. for 3 minutes to produce a pressure-sensitive adhesive layer.

[0119] Production of Polarizing Plate

[0120] A polarizing plate was prepared by laminating the prepared pressure-sensitive adhesive layer on one side of a known polarizing plate on which both sides of a PVA (poly(vinyl alcohol)) series polarizer were protected with a TAC (triacetyl cellulose) protective film having a thickness of about 60 m.

Example 2

[0121] A pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer and a polarizing plate were sequentially produced in the same manner as in Example 1, except that the amount of the ultraviolet absorber of Formula A was changed to a ratio of about 3.5 parts by weight relative to 100 parts by weight of the solid content of the acrylic polymer upon preparing the pressure-sensitive adhesive composition.

Example 3

[0122] A pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer and a polarizing plate were sequentially produced in the same manner as in Example 1, except that the amount of the ultraviolet absorber of Formula A was changed to a ratio of about 3 parts by weight relative to 100 parts by weight of the solid content of the acrylic polymer upon preparing the pressure-sensitive adhesive composition.

Example 4

[0123] A pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer and a polarizing plate were sequentially produced in the same manner as in Example 1, except that the amount of the ultraviolet absorber of Formula A was changed to a ratio of about 2.5 parts by weight relative to 100 parts by weight of the solid content of the acrylic polymer upon preparing the pressure-sensitive adhesive composition.

Example 5

[0124] A pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer and a polarizing plate were sequentially produced in the same manner as in Example 1, except that the amount of the ultraviolet absorber of Formula A was changed to a ratio of about 2 parts by weight relative to 100 parts by weight of the solid content of the acrylic polymer upon preparing the pressure-sensitive adhesive composition.

Comparative Example 1

[0125] A pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer and a polarizing plate were sequentially produced in the same manner as in Example 1, except that an ultraviolet absorber (UV390, manufactured by Eutec, maximum absorption wavelength: 387 nm) of the following Formula B instead of the ultraviolet absorber of Formula A was formulated in an amount of about 0.4 parts by weight relative to 100 parts by weight of the solid content of the acrylic polymer and an ultraviolet absorber (UV1990, manufactured by Eutec, maximum absorption wavelength: 384 nm) of the following Formula C was also formulated in an amount of about 4.5 parts by weight relative to 100 parts by weight of the solid content of the acrylic polymer upon preparing the pressure-sensitive adhesive composition.

##STR00003##

Comparative Example 2

[0126] A pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer and a polarizing plate were sequentially produced in the same manner as in Example 1, except that the ultraviolet absorber (UV390, manufactured by Eutec, maximum absorption wavelength: 387 nm) of Formula B above instead of the ultraviolet absorber of Formula A was formulated in an amount of about 0.4 parts by weight relative to 100 parts by weight of the solid content of the acrylic polymer and the ultraviolet absorber (UV1990, manufactured by Eutec, maximum absorption wavelength: 384 nm) of Formula C above was also formulated in an amount of about 5 parts by weight relative to 100 parts by weight of the solid content of the acrylic polymer upon preparing the pressure-sensitive adhesive composition.

Comparative Example 3

[0127] A pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer and a polarizing plate were sequentially produced in the same manner as in Example 1, except that an ultraviolet absorber (UV1995, manufactured by Eutec) of the following Formula D instead of the ultraviolet absorber of Formula A was formulated in an amount of about 2 parts by weight relative to 100 parts by weight of the solid content of the acrylic polymer upon preparing the pressure-sensitive adhesive composition.

##STR00004##

[0128] Evaluation Example 1 Optical property evaluation of polarizing plate

[0129] The polarizing plates of Examples and Comparative Examples were cut to a size of 25 mm25 mm (widthlength) to prepare specimens. The ultraviolet blocking performance including the blue region was evaluated by measuring the transmittance of the polarizing plate using an ultraviolet-visible light spectrometer (V-7100, manufactured by JASCO), and the results were described in Table 1. The light transmittance in Table 1 below represents the percentage of the light transmission amount when the total light transmittance is set to 100. From Table 1 below, it can be confirmed that Examples 1 to 5 have excellent ultraviolet blocking properties while exhibiting low transmittance for light having a wavelength of 380 nm to 410 nm.

[0130] Evaluation Example 2 Color Characteristic Evaluation of Polarizing Plate

[0131] The polarizing plates of Examples and Comparative Examples were cut to a size of 25 mm25 mm (widthlength) to prepare specimens. The visual appreciation characteristics of the polarizing plate were evaluated by measuring the color coordinates of the polarizing plate using an ultraviolet-visible light spectrometer (V-7100, manufactured by JASCO), and the results were described in Table 1. From the measurement results shown in Table 1, in the case of Examples, the change in the b values is not large, and thus it can be confirmed that they have excellent visual appreciation characteristics.

[0132] From the following Table 1, the ultraviolet absorber having the structure of Formula A above can be applied alone to satisfy the color characteristics required for the polarizing plate, but Comparative Examples 1 and 2 can satisfy the color characteristics required for the polarizing plate only when the pyrazoline-based ultraviolet absorber and the malonic acid-based ultraviolet absorber have been mixed and applied, so that it is effective to apply the pressure-sensitive adhesive composition having the structure specified in the present application. Also, in the case of Comparative Example 3 in which the cyanoacetate-based ultraviolet absorber is applied alone, the specification of the transmittance in a small amount is satisfied, but the value of b is too high and it becomes yellowish, so that it may be a problem in terms of the optical characteristic specification or the visual appreciation. It is an important factor to satisfy the transmittance of less than 0.5% at 380 to 400 nm and less than 5% at 410 nm while suppressing the change in the existing optical characteristics of the polarizing plate.

[0133] Evaluation Example 3 Durability Evaluation Under Reliability Conditions

[0134] Specimens prepared by cutting the polarizing plates prepared in Examples and Comparative Examples to a size of 90 mm170 mm (widthlength) were prepared by two sheets for each of Examples and Comparative Examples. Subsequently, the two specimens as prepared were attached to both sides of a glass substrate (110 mm190 mm0.7 mm=widthlengththickness) so that the optical absorption axes of the respective polarizing plates were crossed to prepare a sample. The pressure applied at the time of attachment was about 5 Kg/cm.sup.2, and the work was performed in a clean room so that bubbles or foreign matters did not occur at the interfaces. The prepared sample was placed in a reliability chamber and allowed to stand for 1,000 hours under the conditions of a temperature of 60 C. and 90% relative humidity, and then the occurrence of lifting at the pressure-sensitive adhesive layer interface was observed. The durability evaluation criteria are as follows.

[0135] <Durability Evaluation Criteria>

[0136] : No lifting occurred

[0137] O: Minor lifting occurred

[0138] : Lifting occurred

[0139] x: Large lifting occurred

TABLE-US-00001 TABLE 1 Transmittance (%) Color coordinates Durability 380 nm 390 nm 400 nm 410 nm a b Example 1 0.00023 0.00062 0.01243 0.23347 3.72935 5.83753 2 0.00074 0.00132 0.02342 0.52392 3.45231 5.52932 3 0.00192 0.00226 0.01253 1.10933 3.13238 5.22412 4 0.00087 0.00426 0.05611 2.17196 2.89218 4.95563 5 0.00323 0.01342 0.23421 4.31381 2.54231 4.68382 Comparative 1 0.00096 0.00643 0.11608 2.82668 3.43324 6.25213 Example 2 0.00041 0.00861 0.12057 2.73922 3.46528 6.31497 3 0.00309 0.10822 0.2716 0.19523 13.0241 23.99735

EXPLANATION OF REFERENCE NUMERALS

[0140] 10: polarizer, 20: retardation layer, 30: pressure-sensitive adhesive layer [0141] 101, 201, 301, 401: polarizer, 102, 202, 302, 402: retardation layer, [0142] 103: upper layer, 203: lower layer, 303: intermediate layer [0143] 403: hard coating layer, 404: polarizer protective film, 405: first pressure-sensitive adhesive layer, 406: retardation layer base film, 407: +C plate, 408: second pressure-sensitive adhesive layer [0144] 100: polarizing plate, 701: substrate, 702: first electrode layer, 703: organic light emitting layer, 704: second electrode layer