Base film, laminated structure including the same, and display device

Abstract

This disclosure relates to a base film, a laminated structure including the same, and a display device. More specifically, this disclosure relates to a base film that includes a polymer having a cyclic olefin-based repeat unit containing exo-isomers above a specific content and a copolymer including a styrene-based repeat unit and a maleimide-based repeat unit, exhibits a high glass transition temperature and thus has excellent heat resistance, and has high light transmittance, a laminated structure including the same, and a display device.

Claims

1. A laminate structure comprising: a base film; and a transparent metal oxide-based conductive film formed on the base film, wherein the base film comprises: a polymer having a cyclic olefin-based repeat unit; and a copolymer including a styrene-based repeat unit and a maleimide-based repeat unit, wherein the content of exo-isomers in the cyclic olefin-based repeat unit is 50 mol % or more, wherein the polymer having a cyclic olefin-based repeat unit is a homopolymer prepared by addition polymerization of one kind of norbornene-based monomers represented by Chemical Formula 2, or a copolymer prepared by addition polymerization of two or more kinds thereof, wherein, in the base film, a weight ratio of the polymer having a cyclic olefin-based repeat unit and the copolymer including a styrene-based repeat unit and a maleimide-based repeat unit is 90:10 to 70:30, wherein the base film has a glass transition temperature of 300 to about 350 C., and wherein the transparent metal oxide-based conductive film is at least one selected from the group consisting of an ITO film, an ATO film, an IZO (indium zinc oxide) film, a tin oxide film, a zinc oxide film, a titanium oxide film, and an antimony oxide film: ##STR00006## wherein, in the Chemical Formula 2, q is an integer of 0 to 4, R1 to R4 are independently a polar functional group or a non-polar functional group, or at least one combination selected from the group consisting of R1 and R2, and R3 and R4, may be connected to each other to form a C1-10 alkylidene group, or R1 or R2 may be connected with one of R3 and R4 to form a C4-12 saturated or an unsaturated aliphatic ring or a C6-24 aromatic ring.

2. The laminate structure according to claim 1, wherein the polymer having a cyclic olefin-based repeat unit has a weight average molecular weight of 10,000 to 1,000,000.

3. The laminate structure according to claim 1, wherein the copolymer including a styrene-based repeat unit and a maleimide-based repeat unit includes 1 to 50 wt % of the styrene-based repeat unit.

4. The laminate structure according to claim 1, wherein the copolymer including a styrene-based repeat unit and a maleimide-based repeat unit has a weight average molecular weight of 500 to 1,000,000.

5. The laminate structure according to claim 1, wherein the non-polar functional group is selected from the group consisting of hydrogen; a halogen; a substituted or unsubstituted C1-20 linear or branched alkyl; a substituted or unsubstituted C2-20 linear or branched alkenyl; a substituted or unsubstituted C2-20 linear or branched alkynyl; a substituted or unsubstituted C3-12 cycloalkyl; a C6-40 aryl; and a substituted or unsubstituted C7-15 aralkyl.

6. The laminate structure according to claim 1, wherein the polar functional group is selected from the group consisting of R.sub.5OR.sub.6, OR.sub.6, OC(O)OR.sub.6, R.sub.5OC(O)OR.sub.6, C(O)OR.sub.6, R.sub.5C(O)OR.sub.6, C(O)R.sub.6, R.sub.5C(O)R.sub.6, OC(O)R.sub.6, R.sub.5OC(O)R.sub.6, (R.sub.50).sub.pOR.sub.6, (OR.sub.5).sub.pOR.sub.6, C(O)OC(O)R.sub.6, R.sub.5C(O)OC(O)R.sub.6, SR.sub.6, R.sub.5SR.sub.6, SSR.sub.6, R.sub.5SSR.sub.6, S(O)R.sub.6, R.sub.5S(O)R.sub.6, R.sub.5C(S)R.sub.6, R.sub.5C(S)SR.sub.6, R.sub.5SO.sub.3R.sub.6, SO.sub.3R.sub.6, R.sub.5NCS, NCS, NCO, R.sub.5NCO, CN, R.sub.5CN, NNC(S)R.sub.6, R.sub.5NNC(S)R.sub.6, NO.sub.2, R.sub.5NO.sub.2, ##STR00007## ##STR00008## ##STR00009## ##STR00010## in the polar functional group, p is independently an integer of 1 to 10; R5 is selected from the group consisting of a substituted or unsubstituted C1-20 linear or branched alkylene, a substituted or unsubstituted C2-20 linear or branched alkenylene, a substituted or unsubstituted C2-20 linear or branched alkynylene, a substituted or unsubstituted C3-12 cycloalkylene, a substituted or unsubstituted C6-40 arylene, a substituted or unsubstituted C7-15 aralkylene, a substituted or unsubstituted C1-20 alkoxylene, and a substituted or unsubstituted C1-20 carbonyloxylene; and R6, R7, and R8 are independently selected from the group consisting of hydrogen, a halogen a substituted or unsubstituted C1-20 linear or branched alkyl, a substituted or unsubstituted C2-20 linear or branched alkenyl, a substituted or unsubstituted C2-20 linear or branched alkynyl, a substituted or unsubstituted C3-12 cycloalkyl, a substituted or unsubstituted C6-40 aryl, a substituted or unsubstituted C7-15 aralkyl, a substituted or unsubstituted C1-20 alkoxy, and a substituted or unsubstituted C1-20 carbonyloxy.

7. The laminate structure according to claim 1, wherein the norbornene-based monomer represented by the Chemical Formula 2 includes at least one selected from the group consisting of a monomer containing a carboxylic acid alkylester functional group, a monomer containing a polar functional group, a monomer containing an acetate group, a monomer containing an alkyl group, and a monomer containing an aryl group.

8. The laminate structure according to claim 1, wherein the styrene-based repeat unit is a repeat unit derived from a compound selected from the group consisting of styrene, -methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 2-methyl-4-chlorostyrene, 2,4,6-trimethylstyrene, cis--methylstyrene, trans--methylstyrene, 4-methyl--methylstyrene, 4-fluoro--methylstyrene, 4-chloro--methylstyrene, 4-bromo--methylstyrene, 4-t-butylstyrene, 2-fluorostyrene, 3-fluorostyrene, 4-fluorostyrene, 2,4-difluorostyrene, 2,3,4,5,6-pentafluorostyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene, octachlorostyrene, 2-bromostyrene, 3-bromostyrene, 4-bromostyrene, 2,4-dibromostyrene, -bromostyrene, -bromostyrene, 2-hydroxystyrene, and 4-hydroxystyrene.

9. The laminate structure according to claim 1, wherein the maleimide-based repeat unit is a repeat unit derived from a compound selected from the group consisting (R)-(+)-N-(1-phenylethyl)maleimide, (S)-()-N-(1-phenylethyl)maleimide, 1,1-(methylenedi-4,1-phenylene)bis-maleimide, 1-(2-methoxy-5-methylphenyl)maleimide, 2,3-dibromo-N-methylmaleimide, 2,3-dibromomaleimide, 22,3-dichloro-N-phenylmaleimide, 2-methyl-N-phenylmaleimide, 4-dimethylaminophenylazophenyl-4-maleimide, biotin-maleimide, bisindolylmaleimide I hydrochloride, bisindolylmaleimide II, bisindolylmaleimide IV, bisindolylmaleimide V, bisindolylmaleimide VII, bisindolylmaleimide VIII, acetate, bisindolylmaleimide X, hydrochloride, bisindolylmaleimide XI, fluorescein diacetate 5-maleimide, maleimide, N,N-(o-phenylene)dimaleimide, N,N-(p-phenylene)dimaleimide, N,N-1,2-phenylenedimaleimide, N,N-1,3-phenylenedimaleimide, N,N-1,4-phenylenedimaleimide, N-(1-naphthyl)-maleimide, N-(1-pyrenyl)maleimide, N-(2,3-xylyl)maleimide, N-(2-aminoethyl)maleimide trifluoroacetate salt, N-(2-ethylphenyl)maleimide, N-(2-methoxyphenyl)maleimide, N-(3-fluoranthyl)maleimide, N-(3-methoxyphenyl)maleimide, N-(4-anilino-1-naphthyl)maleimide, N-(4-chlorophenyl)-maleimide, N-(4-ethylphenyl)maleimide, N-(4-fluorophenyl)maleimide, N-(4-iodophenyl)maleimide, N-(4-nitrophenyl)maleimide, N-(4-phenoxyphenyl)maleimide, N-(7-dimethylamino-4-methyl-3-coumarinyl)maleimide, N-(7-dimethylamino-4-methylcoumarin-3-yl)-maleimide), N-(9-acridinyl)maleimide, N-(ortho-tolyl)-maleimide, N-(para-tolyl)-maleimide, N-benzyl-2,3-dibromomaleimide, N-benzylmaleimide, N-butylmaleimide, N-cyclohexylmaleimide, N-ethylmaleimide, N-hydroxymaleimide, N-methoxycarbonylmaleimide, N-methylmaleimide, N-phenylmaleimide, N-propylmaleimide, N-tert-butylmaleimide, N-[4-(2-benzimidazolyl)phenyl]maleimide, and streptavidin-maleimide.

10. The laminate structure according to claim 1, wherein the base film has light transmittance of 90% or more at 400 to 800 nm.

11. The laminate structure according to claim 1, wherein the base film has a thickness of 20 to 200 m.

12. The laminate structure according to claim 1, wherein the base film is a base of an ITO film for a touch panel or a base of a display device.

13. A display device comprising the laminated structure of claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a photograph showing an assessment result of adhesive strength of the base film prepared according to Example 1.

(2) FIG. 2 is a photograph showing an assessment result of adhesive strength of the base film prepared according to Comparative Example 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) The present invention will be explained in detail with reference to the following examples. However, these examples are only to illustrate the invention, and the scope of the invention is not limited thereto.

EXAMPLES AND COMPARATIVE EXAMPLES: PREPARATION OF A CYCLIC OLEFIN-BASED POLYMER AND A BASE FILM

Example 1

(4) (1) Preparation of a Cyclic Olefin-Based Polymer

(5) 5-norbornene-2-carboxylic acid butyl ester (100 g) with an exo ratio of 71 mol % and 5-norbornene-2-carboxylic acid methyl ester (900 g) with an exo ratio of 71 mol % were introduced into a reactor at room temperature, and toluene (3000 g) was put therein. 1-octyne (10.8 g) was additionally put in the reactor, the inside of the reactor was replaced with nitrogen, and then the temperature of the reactor was raised to 105 C. Subsequently, a catalyst of palladium acetate trimer (0.288 g) and tricyclohexyl phosphonium tetrakis (pentafluorophenyl) borate (2.46 g) were dissolved in a dichloromethane solvent, which was then introduced into the reactor, and reacted for 18 hours while stirring. After the reaction for 18 hours, a white polymer precipitate was obtained using acetone and ethanol. The precipitate was filtered with a filter to recover a polymer, which was dried in a vacuum oven at 60 C. for 24 hours to prepare a copolymer of 5-norbornene-2-carboxylic acid butyl ester and 5-norbornene-2-carboxylic acid methyl ester.

(6) (2) Preparation of a Base Film

(7) 80 wt % of the copolymer of 5-norbornene-2-carboxylic acid butyl ester and 5-norbornene-2-carboxylic acid methyl ester obtained in (1) and 20 wt % of a styrene-maleimide copolymer having a maleimide monomer content of 15 wt % were mixed and dissolved in a methylene chloride (MC) solvent such that the solid content became 20 wt %. The solution was cleanly filtered using a filter having 0.45 m pores to prepare a coating solution.

(8) The coating solution was casted on a glass substrate using a knife coater or a bar coater, and then dried at room temperature for 1 hour, and dried again at 100 C. for 1 hour under a nitrogen atmosphere. After the drying, it was immersed in water for 30 seconds, and then a film on the glass substrate was delaminated to obtain a transparent film with a uniform thickness having a thickness deviation of less than 2%. The thickness, light transmittance at 400 to 800 nm, and glass transition temperature of the prepared film are shown in the following Table 1.

Examples 2 to 5 and Comparative Examples 1 to 2

(9) A copolymer of 5-norbornene-2-carboxylic acid butyl ester and 5-norbornene-2-carboxylic acid methyl ester was prepared by the same method as Example 1, except that the contents of 5-norbornene-2-carboxylic acid butyl ester and 5-norbornene-2-carboxylic acid methyl ester and the ratio of exo were changed as shown in the following Table 1.

(10) The above-prepared cyclic olefin-based polymer and a styrene-maleimide copolymer having a maleimide monomer content of 15 wt % were mixed at a ratio shown in Table 1 to prepare a transparent film.

(11) TABLE-US-00001 TABLE 1 Cyclic olefin based polymer 5-norbornene- 5-norbornene- 2-carboxylic 2-carboxylic acid acid butyl Styrene- methylester ester maleimide content exo content exo content copolymer (g) (mol %) (g) (mol %) (wt %) (wt %) Example 1 900 71 100 71 80 20 Example 2 900 71 100 71 70 30 Example 3 700 71 300 71 80 20 Example 4 700 71 300 71 70 30 Example 5 0 1000 71 95 5 Comparative 900 27 100 27 80 20 Example 1 Comparative 700 27 300 27 80 20 Example 2

Experimental Example 1: Measurement of Physical Properties

(12) The physical properties of each base film prepared in Examples 1 to 5 and Comparative Examples 1 and 2 were measured as follows, and the results are shown in the following Table 2.

(13) (1) Measurement of Phase Difference

(14) The phase difference of each base film obtained in the examples was measured using Axoscan (manufactured by Axomatrix Co. Ltd.), and the thickness of the film was measured together.

(15) Herein, a phase difference in the plane direction is represented by R.sub.e, a phase difference when the angle between incident light and the film side is 50 is represented by R.sub., and a phase difference between the film thickness direction and the y-axis in the plane is represented by R.sub.th.

(16) $\begin{array}{cc}{R}_{\mathrm{th}}=\frac{R_{}\cos {}_f}{{\sin }^2{}_f}& .Math.\mathrm{Mathematical}\mathrm{Equation}1.Math.\end{array}$

(17) In the Mathematical Equation 1, R.sub.th denotes a phase difference in the thickness direction, and .sub.f denotes an internal angle.

(18) (2) Measurement of Light Transmittance

(19) The light transmittance of each base film obtained in the examples and comparative examples was measured using a haze meter.

(20) (3) Measurement of Haze

(21) The haze of each base film obtained in the examples and comparative examples was measured using a haze meter.

(22) (4) Measurement of Refractive Index

(23) The refractive index of each base film obtained in the examples and comparative examples was measured using a prism coupler.

(24) (5) Measurement of Glass Transition Temperature

(25) The glass transition temperature of each base film obtained in the examples and comparative examples was measured using a TMA (thermal mechanical analyzer), wherein the on-set point of the film according to temperature was confirmed.

(26) TABLE-US-00002 TABLE 2 Light thickness transmittance R.sub.e R.sub.th R.sub.th Haze Refractive (m) (%) (nm) (nm) (nm/m) (%) index Tg ( C.) Example 1 50 92 0.1 153 3.06 0.1 1.54 313 Example 2 49 92 0 50 1.02 0.1 1.55 310 Example 3 51 91 0 120 2.35 0.2 1.54 311 Example 4 52 92 0 96 1.84 0.1 1.54 307 Example 5 50 92 0 43 0.86 0.1 1.54 262 Comparative 50 30 83 210 Example 1 Comparative 50 29 91 179 Example 2

(27) As shown in Table 2, Examples 1 to 4 including a polymer having a cyclic olefin-based repeat unit with the content of exo-isomers of 50% or more exhibited light transmittance of 90% or more, while the base film prepared in Comparative Example 1 having a small content of exo-isomers had low solubility to the solvent, and thus the film was opaque and exhibited remarkably low light transmittance of 30% or less compared to the examples. The phase difference and the refractive index of the films of the comparative examples could not be measured because the transparencies of the films were too low.

(28) Further, the base film prepared in the examples exhibited a low phase difference in the thickness direction (R.sub.th) per unit m, and thus it can be applied for a base film of the inside as well as the outside, when used for a display device.

Experimental Example 2: Assessment of Adhesive Strength

(29) The base films prepared in Example 1 and Comparative Example 1 were respectively coated on a COP, and then the adhesive strength was tested by attaching a 3M tape to the base film and instantaneously detaching it, and then confirming the state of the film.

(30) The photographs of the base films of Example 1 and Comparative Example 1 after the adhesion test are respectively shown in FIG. 1 and FIG. 2.

(31) Referring to FIG. 1, the base films including a polymer having a cyclic olefin-based repeat unit with the exo-isomer content of 50 mol % or more according to the examples of the present invention were hardly delaminated in the adhesion test, thus exhibiting good adhesive strength.

(32) To the contrary, referring to FIG. 2, in the base films with the exo-isomer content of less than 50 mol % according to comparative examples, a lot delamination of the base film from the COP film occurred, thus exhibiting inferior adhesive strength.