OPTICAL LAMINATE

Abstract

The present application relates to an optical laminate. The present application can provide an optical laminate having excellent surface properties such as scratch resistance or hardness, which comprises, for example, a cover layer capable of replacing a so-called cover glass.

Claims

1. An optical laminate, comprising: an optical functional layer; and a cover layer formed on top of the optical functional layer, wherein the cover layer comprises at least one hard coat layer and a glass layer comprising a silica network formed of one or more units selected from the group consisting of units of the following formulae A and B:
R.sub.nSiO.sub.(4-n)/2  [Formula A]
SiO.sub.3/2L.sub.1/2  [Formula B] wherein, R is hydrogen, an alkyl group, an alkenyl group, an aryl group, an arylalkyl group, an epoxy group or a (meth)acryloyloxyalkyl group, n is 0 or 1, and L is a divalent linking group comprising any one selected from the group consisting of an alkylene group and an arylene group, or comprising a combination of an alkylene group and an arylene group.

2. The optical laminate according to claim 1, wherein the cover layer has a 500 g steel wool resistance of at least 5,000 times.

3. The optical laminate according to claim 1, wherein the cover layer has a pencil hardness of at least 5 H as measured by a method of drawing a pencil lead on a surface of the cover layer at a load of 500 g and an angle of 45 degrees at a temperature of 25° C. and 50% relative humidity.

4. The optical laminate according to claim 1, wherein the cover layer has a maximum holding curvature radius in a range of 1 to 40 pi as measured by the Mandrel flexure evaluation method according to ASTM D522 standard.

5. The optical laminate according to claim 1, wherein the glass layer further comprises a nitrogen atom and does not contain a linkage (Si—N) of the nitrogen atom and theft silicon atom.

6. The optical laminate according to claim 5, wherein the nitrogen atom is contained in or derived from an amine compound having a pKa of 8 or less.

7. The optical laminate according to claim 5, wherein the nitrogen atom is contained in or derived from an amine compound having a boiling point in a range of 80° C. to 500° C.

8. The optical laminate according to claim 5, wherein the nitrogen atom is contained in or derived from an amine compound having a room temperature vapor pressure of 10,000 Pa or less.

9. The optical laminate according to claim 5, wherein the nitrogen atom is contained in or derived from a compound represented by the following formula 5; an ionic compound having a cationic compound represented by any one of the following formulae 7 to 9 or a compound of the following formula 10: ##STR00020## wherein, R.sub.9 is hydrogen, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 12 carbon atoms, R.sub.11 and R.sub.12 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms, and R.sub.10 is hydrogen, an alkyl group having 1 to 4 carbon atoms, an arylalkyl group having 7 to 16 carbon atoms or a substituent of the following formula 6: ##STR00021## wherein, L.sub.1 is an alkylene group having 1 to 4 carbon atoms: ##STR00022## wherein, R.sub.13 to R.sub.20 are each independently hydrogen or an alkyl group having 1 to 20 carbon atoms: ##STR00023## wherein, R.sub.21 to R.sub.24 are each independently hydrogen or an alkyl group having 1 to 20 carbon atoms: ##STR00024## wherein, R.sub.25 to R.sub.30 are each independently hydrogen or an alkyl group having 1 to 20 carbon atoms: ##STR00025## wherein, L.sub.6 is an alkylene group having 1 to 20 carbon atoms or an alkylidene group having 1 to 20 carbon atoms.

10. The optical laminate according to claim 5, wherein the glass layer contains the nitrogen atom in an amount of 0.0001 to 6 weight %.

11. The optical laminate according to claim 1, wherein the optical functional layer is a polarizing layer or a retardation layer.

12. The optical laminate according to claim 1, wherein the cover layer further comprises a base film, and wherein the hard coat layer comprises an upper hard coat layer formed on the upper surface of the base film and a lower hard coat layer formed on the lower surface of the base film.

13. The optical laminate according to claim 12, wherein the glass layer is formed on top of the upper hard coat layer.

14. The optical laminate according to claim 1, wherein the cover layer further comprises first and second base films.

15. The optical laminate according to claim 14, wherein the hard coat layer comprises first upper and first lower hard coat layers formed on upper and lower sides of the first base film, respectively, and second upper and second lower hard coat layers formed on upper and lower sides of the second base film, respectively.

16. The optical laminate according to claim 15, wherein the glass layer is formed on top of the first or second upper hard coat layer.

17. A display device comprising the optical laminate of claim 1.

Description

BRIEF DESCRIPTIONS OF DRAWINGS

[0205] FIG. 1 is a schematic diagram of a display device comprising an exemplary cover glass.

[0206] FIGS. 2 to 5 are diagrams showing structures of optical laminates comprising various cover layers.

[0207] FIGS. 6 to 8 are views showing evaluation results of polarizing plates of Examples.

[0208] Hereinafter, the optical laminate will be described in more detail through Examples and the like according to the present application, but the scope of the present application is not limited to the following.

[0209] 1. 500 g Steel Wool Resistance Evaluation

[0210] Steel wool resistance was evaluated using a steel wool of grade #0000 sold by Briwax of Europe as the steel wool. The steel wool was contacted with a cover layer under a load of 500 g using a measuring instrument (manufacturer: KIPAE ENT, trade name: KM-M4360), and the steel wool resistance was evaluated while moving it left and right. At this time, the contact area was set so that the width and length were approximately 2 cm and 2 cm or so, respectively (contact area: 2 cm.sup.2). The movement was performed at a speed of about 60 times/min and the moving distance was approximately 10 cm. The steel wool test was performed until reflexes were observed by visual observation and indentations, scratches or ruptures, and the like were identified.

[0211] 2. Pencil Hardness Evaluation

[0212] For measurement of pencil hardness, while the glass layer surface was drawn with a cylindrical pencil lead at a load of 500 g and an angle of 45 degrees using a pencil hardness measuring instrument (manufacturer: Chungbuk Tech, trade name: Pencil Hardness Tester), the hardness of the pencil lead was increased in steps until the occurrence of defects such as indentations, scratches or ruptures was confirmed. Here, the speed of the pencil lead was about 1 mm/sec, and the moving distance was about 10 mm This test was performed at a temperature of about 25° C. and 50% relative humidity.

[0213] 4. Maximum Holding Curvature Radius Evaluation

[0214] The maximum holding curvature radius was evaluated for the cover layer by the Mandrel flexure evaluation method according to ASTM D522 standard.

[0215] 5. Method of Measuring Nitrogen Atom Ratio

[0216] Such a ratio of nitrogen or phosphorus atoms in a glass layer can be measured by X-ray photoelectron spectroscopy (XPS). The method is based on a photoelectric effect and performs the analysis by measuring the kinetic energy of electrons emitted by the photoelectric effect due to the interaction of a surface with high energy light. The binding energy can be measured by emitting core electrons of an element of an analytical sample using X-rays as a light source, and measuring kinetic energy of the emitted electrons. The elements constituting the sample can be identified by analyzing the measured binding energy, and information on the chemical bonding state and the like can be obtained through chemical shift. In the present application, after a glass layer is formed on a silicon wafer to a thickness of about 0.5 μm to 3 μm or so, the ratio of nitrogen or phosphorus atoms can be measured in the manner described in each example or the like. In this case, the specific kind of the applied measuring equipment is not particularly limited as long as it is capable of the measurement of the photoelectron spectroscopy.

[0217] 6. Measurement of Thickness

[0218] After taking an SEM (scanning electron microscope) photograph about a cover layer, thicknesses of a base film, a hard coat layer, a glass layer, etc. contained in the cover layer were confirmed based on the photograph.

[0219] 7. Water Vapor Transmission Rate (WVTR) Evaluation

[0220] The water vapor transmission rate was evaluated for a glass layer according to ASTM F1249 standard. It was evaluated after the glass layer was formed on a PET (poly(ethylene terephthalate)) film having a thickness of 50 μm to a thickness of about 1 μm in the same manner as described in each of the following examples. Here, the applied PET film has a water vapor transmission rate of approximately 3.9 to 4.1 g/m.sup.2/day when equally measured according to ASTM F1249 standard.

[0221] 8. Heating Test

[0222] Using an instrument equipped with a touch tip (K-9232, MIK21), the heating test on a cover layer was performed by heating the cover layer with the touch tip. At this time, it was performed by setting the pressure on heating as a level of about 250 gf and setting the once heating time as 0.5 seconds.

[0223] 9. Writing Test

[0224] The writing test on a cover layer was performed using an instrument equipped with a touch tip (K-9700, MIK21). The writing ranges were set such that the X-axis, Y-axis and Z-axis ranges were 700 mm, 550 mm and 100 mm, respectively, and the pressure on writing was set as a level of about 250 gf.

EXAMPLE 1

Production of Cover Layer

[0225] 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane and 3 -glycidoxypropyl trimethoxysilane were condensed in a molar ratio of 1:1 in a known dehydration/condensation manner to prepare an oligomer (polyorganosiloxane), thereby forming a hard coat layer. The average unit of this oligomer is approximately (R.sup.1SiO.sub.3/2).sub.0.5(R.sup.2SiO.sub.3/2), wherein R.sup.1 is a 2-(3,4-epoxycyclohexyl)ethyl group and R.sup.2 is a 3-glycidoxypropyl group. The oligomer and a cationic photoinitiator (CPI-100P, San-Apro) were further mixed to prepare a composition for a hard coat layer. The cationic photoinitiator was applied at a ratio of approximately 5 to 6 parts by weight relative to 100 parts by weight of the oligomer. After coating the composition for the hard coat layer on one surface of a base film (ZRT, Zero Retardation TAC, FujiFilm) having a thickness of about 40 μm or so as a base film, it was dried at a temperature of 80° C. or so for about 2 minutes and then irradiated with ultraviolet rays at a light quantity of about 1,000 mJ/cm.sup.2 using an ultraviolet irradiation instrument (Fusion, D bulb) and cured, thereby forming a hard coat layer having a thickness of about 30 μm o so. A hard coat layer having a thickness of about 30 μm or so was formed on the other side of the base film in the same manner (double-sided hard coat film having a structure of hard coat layer/base film/hard coat layer).

[0226] Subsequently, a glass layer was formed on any one hard coat layer of the double-sided hard coat film. TEOS (tetraethoxy silane), ethanol (EtOH), water (H.sub.2O) and hydrochloric acid (HCl) were mixed in a weight ratio of 1:4:4:0.2 (TEOS: EtOH: H.sub.2O: HCl) and stirred at room temperature (25° C.) for 3 days or so to form a silica precursor composition. The silica precursor composition was applied on the hard coat layer by a bar coating method and dried at 80° C. for 1 minute or so. After drying, the layer of the silica precursor composition was subjected to atmospheric plasma treatment and then immersed in trioctylamine (TOA) (pKa: 3.5, boiling point: about 366° C., flash point: about 163° C., room temperature vapor pressure: about 0.002 Pa), which was maintained at a temperature of 80° C. or so, for approximately 5 minutes or so to form a glass layer. The formed silica glass layer was washed with running water at 60° C. or so for 2 minutes or so and dried in an oven at 80° C. or so for 1 minute. The amount of nitrogen atoms in the produced glass layer was about 0.005 weight % or so, the water vapor transmission rate of the glass layer was in a level of approximately 3.9 to 4.0 g/m.sup.2/day, and the maximum holding curvature radius of the cover layer was about 2 pi or so.

Manufacture of Polarizing Plate

[0227] The hard coat layer without the formed glass layer in the above-produced cover layer (glass layer/hard coat layer/base film/hard coat layer) was attached to a polarizing plate structure comprising a polarizing layer with an adhesive to produce a polarizing plate. Here, a structure, in which a protective film (ZRT (Zero Retardation TAC) film, FujiFilm, thickness: about 40 μm) was attached to both sides of a known PVA (poly(vinyl alcohol)) film polarizing layer (thickness: about 12 μm), was used as the polarizing plate structure, and a known epoxy-based adhesive layer was used as the adhesive layer. Subsequently, a pressure-sensitive adhesive layer was formed on the bottom of the lower protective film in the structure of the obtained glass layer/hard coat layer/base film/hard coat layer/adhesive layer/protective film/polarizing layer/protective film to produce a polarizing plate. As a result of performing the heating test on the surface (cover layer surface) of the polarizing plate in the above-described manner, no damage was observed until the heating of 1,000,000 times, and the result was shown in FIG. 6. Also, as a result of performing the writing test on the surface (cover layer surface) of the polarizing plate in the above-described manner, no damage was observed until the writing of 100,000 times, and the result was shown in FIG. 7. Furthermore, as a result of performing the steel wool test on the surface (cover layer surface) of the polarizing plate, no damage was observed until 10,000 times, and the result was shown in FIG. 8. In addition, the pencil hardness measured on the surface of the cover layer was in a level of approximately 9 H. On the other hand, the maximum holding curvature radius of the polarizing plate was 8 pi on the inside (when the polarizing plate was concavely bent inward based on the cover layer) and 40 pi on the outside (when the polarizing plate was convexly bent outwards based on the cover layer).

EXAMPLE 2

[0228] A cover layer and a polarizing plate were produced in the same manner as in Example 1, except that the formation method of the glass layer was changed as follows. TEOS (tetraethoxy silane), ethanol (EtOH), water (H.sub.2O) and hydrochloric acid (HCl) were mixed in a weight ratio of 1:4:4:0.01 (TEOS: EtOH: H.sub.2O: HCl) and stirred at 65° C. for 1 hour or so to form a silica precursor composition. The silica precursor composition was applied to the hard coat layer by a bar coating method and dried at 80° C. for 1 minute or so. After drying, the layer of the silica precursor composition was subjected to atmospheric plasma treatment and then immersed in trioctylamine (TOA) (pKa: 3.5, boiling point: about 366° C., flash point: about 163° C., room temperature vapor pressure: about 0.002 Pa), which was maintained at a temperature of 80° C. or so, for approximately 5 minutes or so to form a glass layer. The formed glass layer was washed with running water at 60° C. or so for 2 minutes or so and dried in an oven at 80° C. or so for 1 minute. The amount of nitrogen atoms in the produced glass layer was 0.005 weight % or so, the water vapor transmission rate (WVTR) of the glass layer was 3.9 to 4.0 g/m.sup.2/day or so, and the maximum holding curvature radius of the cover layer was 2 pi or so.

[0229] As a result of performing the heating test on the cover layer surface in the polarizing plate in the above-described manner, no damage was observed until the heating of 1,000,000 times, as a result of performing the writing test, no damage was observed until the writing of 100,000 times, and as a result of performing the steel wool test, no damage was observed until 7,000 times. In addition, the pencil hardness measured on the surface of the cover layer was in a level of approximately 9H, the maximum holding radius of curvature was 8 pi on the inside and 40 pi or so on the outside.

EXAMPLE 3

[0230] A cover layer and a polarizing plate were produced in the same manner as in Example 1, except that the formation method of the glass layer was changed as follows. BTEST (bis(triethoxysilyl) ethane), ethanol (EtOH), water (H.sub.2O) and hydrochloric acid (HCl) were mixed in a weight ratio of 1:6:6:0.01 (BTEST: EtOH: H.sub.2O: HCl) and stirred at 65° C. for 1 hour or so to form a silica precursor composition. The silica precursor composition was applied to the hard coat layer to a thickness of approximately 10 μm or so by a bar coating method and dried at 80° C. for 1 minute or so. After drying, the layer of the silica precursor composition was subjected to atmospheric plasma treatment and then immersed in trioctylamine (TOA) (pKa: 3.5, boiling point: about 366° C., flash point: about 163° C., room temperature vapor pressure: about 0.002 Pa), which was maintained at a temperature of 80° C. or so, for approximately 5 minutes or so to form a glass layer. The formed glass layer was washed with running water at 60° C. or so for 2 minutes or so and dried in an oven at 80° C. or so for 1 minute. The ratio of nitrogen atoms in the produced glass layer was about 0.005 weight % or so, the water vapor transmission rate (WVTR) was 3.9 to 4.0 g/m.sup.2/day or so, and the maximum holding curvature radius of the cover layer was in a level of 2 pi. As a result of performing the heating test on the cover layer surface in the polarizing plate in the above-described manner, no damage was observed until the heating of 1,000,000 times, as a result of performing the writing test, no damage was observed until the writing of 100,000 times, and as a result of performing the steel wool test, no damage was observed until 8,000 times. In addition, the pencil hardness measured on the surface of the cover layer was in a level of approximately 8 H, the maximum holding curvature radius was 8 pi on the inside and 40 pi or so on the outside.

EXAMPLE 4

[0231] A cover layer and a polarizing plate were produced in the same manner as in Example 1, except that the formation method of the glass layer was changed as follows. TEOS (tetraethoxy silane), ethanol (EtOH), water (H.sub.2O) and hydrochloric acid (HCl) were mixed in a weight ratio of 1:4:4:0.01 (TEOS: EtOH: H.sub.2O: HCl) and stirred at 65° C. for 1 hour or so to form a silica precursor composition. Approximately 4 parts by weight of a latent base generator (Formula F below, WPBG-018, WAKO) was mixed therewith relative to 100 parts by weight of the solid content of the silica precursor composition.

##STR00013##

[0232] The silica precursor composition mixed with the latent base generator was applied on the hard coat layer by a bar coating method and dried at 80° C. for 1 minute or so. After drying, the silica precursor composition was irradiated with ultraviolet rays at a light quantity of about 660mJ/cm.sup.2 using an ultraviolet irradiation instrument (Fusion, D bulb) to form a glass layer. The amount of nitrogen atoms in the produced glass layer was 0.15 to 0.18 weight % or so, the maximum holding curvature radius of the cover layer was 2 pi or so, and the water vapor transmission rate (WVTR) of the glass layer was 3.9 to 4.0 g/m.sup.2/day or so.

[0233] As a result of performing the heating test on the cover layer surface in the polarizing plate in the above-described manner, no damage was observed until the heating of 1,000,000 times, as a result of performing the writing test, no damage was observed until the writing of 100,000 times, and as a result of performing the steel wool test, no damage was observed until 6,000 times. In addition, the pencil hardness measured on the surface of the cover layer was in a level of approximately 8 H, the maximum holding curvature radius was 8 pi on the inside and 40 pi or so on the outside.

EXAMPLE 5

[0234] A cover layer and a polarizing plate were produced in the same manner as in Example 1, except that the formation method of the glass layer was changed as follows.

[0235] BTESE (bis(triethoxysilyl) ethane), ethanol (EtOH), water (H.sub.2O) and hydrochloric acid (HCl) were mixed in a weight ratio of 1:6:6:0.01 (BTESE: EtOH: H.sub.2O: HCl) and stirred at 65° C. for 1 hour or so to form a silica precursor composition. Approximately 4 parts by weight of a latent base generator (Formula F below, WPBG-018, WAKO) was mixed therewith relative to 100 parts by weight of the solid content of the silica precursor composition.

##STR00014##

[0236] The silica precursor composition mixed with the latent base generator was applied on the hard coat layer by a bar coating method and dried at 80° C. for 1 minute or so. After drying, the silica precursor composition was irradiated with ultraviolet rays at a light quantity of about 660 mJ/cm.sup.2 using an ultraviolet irradiation instrument (Fusion, D bulb) to form a glass layer. The amount of nitrogen atoms in the produced glass layer was 0.15 to 0.18 weight % or so, the maximum holding curvature radius of the cover layer was 2 pi or so, and the water vapor transmission rate (WVTR) of the glass layer was 3.9 to 4.0 g/m.sup.2/day or so.

[0237] As a result of performing the heating test on the cover layer surface in the polarizing plate in the above-described manner, no damage was observed until the heating of 1,000,000 times, as a result of performing the writing test, no damage was observed until the writing of 100,000 times, and as a result of performing the steel wool test, no damage was observed until 7,000 times. In addition, the pencil hardness measured on the surface of the cover layer was in a level of approximately 8 H, the maximum holding curvature radius was 8 pi on the inside and 40 pi or so on the outside.

EXAMPLE 6

[0238] A cover layer and a polarizing plate were produced in the same manner as in Example 1, except that the formation method of the glass layer was changed as follows.

[0239] TEOS (tetraethoxy silane), ethanol (EtOH), water (H.sub.2O) and hydrochloric acid (HCl) were mixed in a weight ratio of 1:4:4:0.01 (TEOS: EtOH: H.sub.2O: HCl) and stirred at 65° C. for 1 hour or so to form a silica precursor composition. Approximately 2 parts by weight of a latent base generator (Formula G below, C11Z, Shikoku chemical) was mixed therewith relative to 100 parts by weight of the solid content of the silica precursor composition.

##STR00015##

[0240] The silica precursor composition mixed with the latent base generator was applied on the hard coat layer by a bar coating method and dried at 80° C. for 1 minute or so. After drying, the silica precursor composition was maintained at approximately 120° C. for 10 minutes to form a glass layer. The amount of nitrogen atoms in the produced glass layer was 0.22 to 0.24 weight % or so, the maximum holding curvature radius of the cover layer was 2 pi or so, and the water vapor transmission rate (WVTR) of the glass layer was 3.9 to 4.0 g/m.sup.2/day or so.

[0241] As a result of performing the heating test on the cover layer surface in the polarizing plate in the above-described manner, no damage was observed until the heating of 1,000,000 times, as a result of performing the writing test, no damage was observed until the writing of 100,000 times, and as a result of performing the steel wool test, no damage was observed until 7,000 times. In addition, the pencil hardness measured on the surface of the cover layer was in a level of approximately 9 H, the maximum holding curvature radius was 8 pi on the inside and 40 pi or so on the outside.

EXAMPLE 7

[0242] A cover layer and a polarizing plate were produced in the same manner as in Example 1, except that the formation method of the glass layer was changed as follows.

[0243] BTESE (bis(triethoxysilyl) ethane), ethanol (EtOH), water (H.sub.2O) and hydrochloric acid (HCl) were mixed in a weight ratio of 1:6:6:0.01 (BTESE: EtOH: H.sub.2O: HCl) and stirred at 65° C. for 1 hour or so to form a silica precursor composition. Approximately 2 parts by weight of a latent base generator (Formula G below, C11Z, Shikoku chemical) was mixed therewith relative to 100 parts by weight of the solid content of the silica precursor composition.

##STR00016##

[0244] The silica precursor composition mixed with the latent base generator was applied on the hard coat layer by a bar coating method and dried at 80° C. for 1 minute or so. After drying, the silica precursor composition was maintained at approximately 120° C. for 10 minutes to form a glass layer. The amount of nitrogen atoms in the produced glass layer was 0.22 to 0.24 weight % or so, the maximum holding curvature radius of the cover layer was 2 pi or so, and the water vapor transmission rate (WVTR) of the glass layer was 3.9 to 4.0 g/m.sup.2/day or so.

[0245] As a result of performing the heating test on the cover layer surface in the polarizing plate in the above-described manner, no damage was observed until the heating of 1,000,000 times, as a result of performing the writing test, no damage was observed until the writing of 100,000 times, and as a result of performing the steel wool test, no damage was observed until 8,000 times. In addition, the pencil hardness measured on the surface of the cover layer was in a level of approximately 8 H, the maximum holding curvature radius was 8 pi on the inside and 40 pi or so on the outside.

EXAMPLE 8

[0246] A cover layer and a polarizing plate were produced in the same manner as in Example 1, except that the formation method of the glass layer was changed as follows.

[0247] BTESE (bis(triethoxysilyl) ethane), ethanol (EtOH), water (H.sub.2O) and hydrochloric acid (HCl) were mixed in a weight ratio of 1:6:6:0.01 (BTESE: EtOH: H.sub.2O: HCl) and stirred at 65° C. for 1 hour or so to form a silica precursor composition. Approximately 2 parts by weight of a latent base generator (Formula H below, C17Z, Shikoku chemical) was mixed therewith relative to 100 parts by weight of the solid content of the silica precursor composition.

##STR00017##

[0248] The silica precursor composition mixed with the latent base generator was applied on the hard coat layer by a bar coating method and dried at 80° C. for 1 minute or so. After drying, the silica precursor composition was maintained at approximately 120° C. for 10 minutes to form a glass layer. The amount of nitrogen atoms in the produced glass layer was 0.14 to 0.17 weight % or so, the maximum holding curvature radius of the cover layer was 2 pi or so, and the water vapor transmission rate (WVTR) of the glass layer was 3.9 to 4.0 g/m.sup.2/day or so.

[0249] As a result of performing the heating test on the cover layer surface in the polarizing plate in the above-described manner, no damage was observed until the heating of 1,000,000 times, as a result of performing the writing test, no damage was observed until the writing of 100,000 times, and as a result of performing the steel wool test, no damage was observed until 7,000 times. In addition, the pencil hardness measured on the surface of the cover layer was in a level of approximately 7 H, the maximum holding curvature radius was 8 pi on the inside and 40 pi or so on the outside.

EXAMPLE 9

[0250] A cover layer and a polarizing plate were produced in the same manner as in Example 1, except that the formation method of the glass layer was changed as follows.

[0251] BTESE (bis(triethoxysilyl) ethane), ethanol (EtOH), water (H.sub.2O) and hydrochloric acid (HCl) were mixed in a weight ratio of 1:6:6:0.01 (BTESE: EtOH: H.sub.2O: HCl) and stirred at 65° C. for 1 hour or so to form a silica precursor composition. Approximately 2 parts by weight of a latent base generator (Formula I below, 2MZ-H, Shikoku chemical) was mixed therewith relative to 100 parts by weight of the solid content of the silica precursor composition.

##STR00018##

[0252] The silica precursor composition mixed with the latent base generator was applied on the hard coat layer by a bar coating method and dried at 80° C. for 1 minute or so. After drying, the silica precursor composition was maintained at approximately 120° C. for 10 minutes to form a glass layer. The amount of nitrogen atoms in the produced glass layer was 0.64 to 0.67 weight % or so, the maximum holding curvature radius of the cover layer was 2 pi or so, and the water vapor transmission rate (WVTR) of the glass layer was 3.9 to 4.0 g/m.sup.2/day or so.

[0253] As a result of performing the heating test on the cover layer surface in the polarizing plate in the above-described manner, no damage was observed until the heating of 1,000,000 times, as a result of performing the writing test, no damage was observed until the writing of 100,000 times, and as a result of performing the steel wool test, no damage was observed until 6,000 times. In addition, the pencil hardness measured on the surface of the cover layer was in a level of approximately 7 H, the maximum holding curvature radius was 8 pi on the inside and 40 pi or so on the outside.

EXAMPLE 10

[0254] A cover layer and a polarizing plate were produced in the same manner as in Example 1, except that the formation method of the glass layer was changed as follows.

[0255] BTESE (bis(triethoxysilyl) ethane), ethanol (EtOH), water (H.sub.2O) and hydrochloric acid (HCl) were mixed in a weight ratio of 1:6:6:0.01 (BTESE: EtOH: H.sub.2O: HCl) and stirred at 65° C. for 1 hour or so to form a silica precursor composition. Approximately 2 parts by weight of a latent base generator (Formula J below, 1B2MZ, Shikoku chemical) was mixed therewith relative to 100 parts by weight of the solid content of the silica precursor composition.

##STR00019##

[0256] The silica precursor composition mixed with the latent base generator was applied on the hard coat layer by a bar coating method and dried at 80° C. for 1 minute or so. After drying, the silica precursor composition was maintained at approximately 120° C. for 10 minutes to form a glass layer. The nitrogen atom amount contained inside the produced glass layer was 0.29 to 0.32 weight % or so, the maximum holding curvature radius of the cover layer was 2 pi or so, and the water vapor transmission rate (WVTR) of the glass layer was 3.9 to 4.0 g/m.sup.2/day or so.

[0257] As a result of performing the heating test on the cover layer surface in the polarizing plate in the above-described manner, no damage was observed until the heating of 1,000,000 times, as a result of performing the writing test, no damage was observed until the writing of 100,000 times, and as a result of performing the steel wool test, no damage was observed until 6,000 times. In addition, the pencil hardness measured on the surface of the cover layer was in a level of approximately 6 H, the maximum holding curvature radius was 8 pi on the inside and 40 pi or so on the outside.