Optical layered body, polarizer and image display device

Abstract

The present invention provides an optical layered body having excellent antistatic properties, optical characteristics, hardness, adhesion, and interference fringe prevention performance, which can be produced at a low cost. An optical layered body having a hard coat layer provided on a triacetylcellulose substrate, wherein a resin composition used for forming the hard coat layer contains a quaternary ammonium salt-containing polymer, a binder resin, and a solvent; the quaternary ammonium salt-containing polymer has a higher hydrophilicity than the binder resin; and the binder resin contains two or more resin components having different hydrophilicities.

Claims

1. A method for localizing a quaternary ammonium salt-containing polymer in a hard coat layer provided on a triacetylcelulose substrate of an optical layered body, which method comprises: applying a resin composition to the triacetylcelulose substrate for forming the hard coat layer, the resin composition containing a quaternary ammonium salt-containing polymer, a binder resin, and a solvent, wherein the solvent is a mixed solvent containing two or more solvents having different hydrophilicities and wherein less than 50% by mass of the mixed solvent is a hydrophilic solvent, selecting the quaternary ammonium salt-containing polymer to have a higher hydrophilicity than the binder resin, and selecting the binder resin to contain two or more resin components having different hydrophilicities, wherein the quaternary ammonium salt-containing polymer is localized in an upper part of the formed hard coat layer.

2. The method for localizing a quaternary ammonium salt containing polymer in a hard coat layer according to claim 1, wherein the quaternary ammonium salt-containing polymer is a copolymerized product of a dimethylaminoethyl methacrylate quaternary ammonium salt and a (meth)acrylate compound at a mass ratio of 1/99 to 90/10.

3. The method for localizing a quaternary ammonium salt-containing polymer in a hard coat layer according to claim 1, wherein the quaternary ammonium salt-containing polymer is contained in an amount of 1.0 to 10% by mass in the solids content of the resin composition.

4. The method for localizing a quaternary ammonium salt-containing polymer in a hard coat layer according to claim 1, wherein the two or more resin components having different hydrophilicities are a monomer having a weight-average molecular weight of 600 or less and an oligomer having a weight-average molecular weight of 1,000 to 10,000, and the hydrophilicity of the monomer is higher than that of the oligomer.

5. The method for localizing a quaternary ammonium salt-containing polymer in a hard coat layer according to claim 4, wherein the monomer having a weight-average molecular weight of 600 or less includes at least one selected from the group consisting of pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, polyester tri(meth)acrylate, polyester di(meth)acrylate, isocyanuric acid ethylene oxide-modified tri(meth)acrylate, isocyanuric acid ethylene oxide-modified di(meth)acrylate, polyester ethylene oxide-modified tri(meth)acrylate, ethylene oxide-modified di(meth)acrylate, and propylene oxide-modified di(meth)acrylate, and the oligomer having a weight-average molecular weight of 1,000 to 10,000 is a urethane (meth)acrylate.

6. The method for localizing a quaternary ammonium salt-containing polymer in a hard coat layer according to claim 1, wherein the solvent contains a penetrating solvent having an ability to penetrate the triacetylcellulose substrate.

7. The method for localizing a quaternary ammonium salt-containing polymer in a hard coat layer according to claim 6, wherein, when the resin composition is applied to the substrate, the penetrating solvent and a binder resin component having a higher hydrophilicity penetrate into a surface of the substrate and the quaternary ammonium salt-containing polymer and a binder resin component having a lower hydrophilicity remain at the surface of the substrate with another member of the mixed solvent.

8. The method for localizing a quaternary ammonium salt-containing polymer in a hard coat layer according to claim 1, wherein the optical layered body has a surface resistance value of 110.sup.11 / or less, and a haze of 0.7% or less.

9. The method for localizing a quaternary ammonium salt-containing polymer in a hard coat layer according to claim 1, wherein the amount of the quaternary ammonium salt-containing polymer is 1.5% to 3.0% by mass of the solids content of the resin composition.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGS. 1(a) and 1(b) each show an example of a cross-sectional schematic diagram showing a formation mechanism of a hard coat layer in the optical layered body of the present invention, which is produced using the resin composition of the present invention; and FIG. 1 (c) is a cross-sectional view schematically showing the optical layered body of the present invention provided with a low-refractive index layer.

DESCRIPTION OF EMBODIMENTS

(2) The present invention is described with reference to the following examples; however, the present invention should not be interpreted by limiting to these examples. Additionally, parts and % are mass basis unless otherwise specified.

EXAMPLE 1

(3) The following composition, was formulated to prepare a resin composition. Quaternary ammonium salt-containing polymer A (ACRIT 1SX-3000, weight-average molecular weight (Mw) of 10,000 to 40,000, produced by Taisei Fine Chemical Co., Ltd,): 3 parts by mass in terms of solids content Dipentaerythritol hexaacrylate (DPHA) (hexa-functional, weight-average molecular weight (Mw) of 524, produced by Nippon Kayaku Co., Ltd,): 27 parts by mass BS577 (Beamset 577, urethane acrylate, Mw of 1,000, produced by Arakawa Chemical industries, Ltd,): 70 parts by mass Photopolymerization initiator (Irgacure 184, produced by Ciba Japan K.K.); 4 parts by mass Methyl ethyl ketone (MEK); 85 parts by mass N-butanol: 15 parts by mass

(4) The thus-obtained resin composition was applied to a triacetylcellulose (TAC) substrate (thickness of 80 m, TD80ULN (trade name), produced by FUJIFILM Corporation) in an coating amount (dry) of 15 g/m.sup.2 (dry film thickness of 12 m), and dried at 70 for 60 seconds to form a coating film. Subsequently, 200 mJ/cm.sup.2 of ultraviolet light was applied to the coating film to cure the same so as to form a hard coat layer, thereby obtaining an optical layered body.

EXAMPLES 2 TO 10 AND 12 TO 15; COMPARATIVE EXAMPLES 1 To 6; AND REFERENCE EXAMPLES 1 TO 10

(5) Each optical layered body was produced in the same manner as in Example 1, except that the components of the resin composition for the hard coat layer were changed as shown in Table 1 and the substrate was changed as shown in Table 2.

(6) Note that quaternary ammonium salt-containing polymers, resins, substrates, and the like, which are shown in Table 1 but not mentioned above, are specifically as described below.

(7) Additionally, the numerical values in the columns under Parts by mass of the binder resins in Table 1 indicate the proportion of each resin in the mixture.

(8) >Quaternary Ammonium Salt-Containing Polymer<

(9) B: H6S00 (about 10% of the solids content is quaternary ammonium salt-containing polymer, and about 90% is DPHA), Mw of 10,000, produced by Mitsubishi Chemical Corporation, 50% solids content (solvent MEK, alcohol.) C: quaternary ammonium salt-containing polymer of H6500, with Mw of 22,000 D: quaternary ammonium salt-containing polymer of H6500, with Mw of 4,500
>Binder Resin< PETA: pentaerythritol triacrylate, Mw of 298 UV1700B: Seiko UV1700B, urethane aerylate, Mw of 2,000, produced by Nippon Synthetic Chemical Industry Co., Ltd. DPHA40H: DPHA40H, urethane acrylate, Mw of 7000, produced by Nippon Kayaku Co., Ltd,. HOP; Light Ester HOP, mono-functional monomer, Mw of 144, produced by Kyoeisha Chemical Co., Ltd. DCPA: Light Ester DCPA, di-functional monomer, Mw of 303, produced by Kyoeisha Chemical Co., Ltd. M9050; a mixed resin of polyester ethylene oxide (EO)-modified triacrylate and isocyanuric acid EO-modified triacrylate, Mw of about 420, produced by Toagosei Co., Ltd. M8030: polyester triacrylate, Mw of about 400, produced by Toagosei Co., Ltd., tri-functional UN904: Artresin UN904, arethane acrylate, Mw of 4,900, produced by Negami Chemical Industrial Co., Ltd., deca-functional V802: V802, nona-functional monomer, Mw of 1,000, produced by Osaka Organic Chemical Industry Ltd. EBECRYL 8210: urethane acrylate, Mw of 600, functional group number of 4, produced by DAICEL-CYTEC Company, Ltd. UX-3204; urethane acrylate, Mw of 13,000, functional group number of 2, produced by Nippon Kayaku Co., Ltd. EBECRYL 885: polyester acrylate, Mw of 6,000, functional group number of 5, produced by DAICEL-CYTEC Company, Ltd.
>Substrate<

(10) PET substrate: A4300 produced by Toyobo Co., Ltd., thickness of 188 m

EXAMPLE 11

(11) In the same manner as in Example 1, a hard coat layer was formed, on a triacetylcellulose (TAC) substrate, and subsequently, a composition for a low-refractive index layer having the following composition was applied to the hard coat layer to form a coating film (dry film thickness of 100 nm), dried in a thermal oven at a temperature of 70 C. for 60 seconds to evaporate solvents in the coating film. Then, ultraviolet light was applied thereto in such a manner that the cumulative amount of light would be 200 mJ to cure the coating film. Thereby, a low-refractive index layer was further formed and an optical layered body was obtained.

(12) >Composition for the Low-Refractive Index Layer<

(13) Hollow silica fine particles (solids content of the silica fine particles; 20% by mass solution; methyl isobutyl ketone; average particle size of 50 nm): 73 parts by mass Fluorine atom-containing polymer (produced by JSR Corporation; Opster TU2224; 20% solids content; methyl isobutyl ketone as the solvent): 2 parts by mass in terms of solids content Fluorine atom-containing monomer (produced by Kyoeisha Chemical Co. Ltd.; LINC3A; refractive index of 1.42; 100% solids content): 5 parts by mass Pentaerythritol triacrylate (PETA): 3 parts by mass Polymerization initiator (Irgacure 127, produced by Ciba Japan K.K.): 0.35 parts by mass Silicone/fluorine-containing antifouling agent (TU2225, produced by JSR Corporation) 0.5 parts by mass in terms of solids content Methyl isobutyl ketone (MIBK): 320 parts by mass Propylene glycol monomethyl ether (PGME): 161 parts by mass
(Hydrophilicity)

(14) The above-described quaternary ammonium salt-containing polymers and binder resins were individually used and cared on the PET substrate to a dry film thickness of 7 m (irradiation amount of ultraviolet light: 200 mJ/cm.sup.2) to form a coating film, and the water contact angle of the coating film was measured by CA-X model produced by Kyowa Interface Science Co., Ltd. The results are shown below: DPHA: 74 degrees PETA: 68 degrees M9050: 75 degrees BS577: 72 degrees M8030: 76 degrees UV1700B: 83 degrees UN904: 80 degrees DPHA40H: 80 degrees DCPA: 70 degrees HOP: 65 degrees V802: 74 degrees EBECRYL 8210: 71 degrees UX-3204: 80 degrees EBECRYL 885: 72 degrees Quaternary ammonium salt-containing polymer: 70 degrees

(15) The thus-obtained optical layered body was evaluated in terms of the following items. Table 2 shows the results.

(16) (Surface Resistance)

(17) The surface resistance value (/) was measured at an applied voltage of 500 V using a surface resistivity meter (produced by Mitsubishi Chemical Corporation; product number; Hiresta IP MCP-HT260).

(18) (Presence or Absence of Interference Fringe)

(19) A black tape for preventing back reflection was attached to the optical layered body, on the side opposite to the hard coat layer. The optical layered body was visually observed from the hard coat layer side, and occurrence of an interference fringe was evaluated.

(20) An interference fringe was graded as absent when there was no interference fringe and the visibility was good, or as present when an interference fringe was formed.

(21) (Haze)

(22) The haze value (%) was measured in accordance with JIS K-7136 using a haze meter (produced by Murakami Color Research laboratory; product number: HM-150).

(23) (Adhesion)

(24) In accordance with JIS K-5600, 100 cross-cuts (11 mm square) were made on the hard coat layer of the optical layered body, and a peeling test was performed 5 times in succession using Cello-tape (registered trade mark) with a width of 24 mm, produced by Nichiban Co., Ltd. The number of retaining cross-cuts was counted. When all the cross-cuts remained without any peeling, the result was rated good. When at least one cross-cut was peeled, the result was rated poor.

(25) (Transmittance)

(26) The total light transmittance was measured in accordance with JIS R-7361 using a base meter (produced by Murakami Color Research Laboratory; product number: HM-150).

(27) (Pencil Hardness)

(28) The optical layered body was subjected to humidity conditioning at a temperature of 25 C. and a relative humidity of 50% for 2 hours. Subsequently, with a use of test pencils (hardness of H to 3H) specified in JIS S-6006, the pencil hardness test was performed under a load of 4.9 N in accordance with a pencil hardness evaluation method specified in JIS K 5600-5-4 (1999). Each optical layered body was scratched 5 times, and the pencil hardness with which the number of scratch marks was less than 4 was defined as the hardness in the test.

(29) TABLE-US-00001 TABLE 1 Quaternary Binder resin Monomer component Binder resin Oligomer component Solvent Photopo- Water ammonium Hydro- Hydro- (parts by lymer- content salt-containing philicity philicity mass) ization (%) in Parts Contact Parts Contact Parts n- initiator the resin by angle by angle by Bu- (parts by compo- Type mass Type (degree) Mw mass Type (degree) Mw mass MEK tanol mass) sition Example 1 A 3 DPHA 74 534 27 BS577 72 1000 70 85 15 4 1 Example 2 A 3 DPHA 74 534 27 UV1700B 83 2000 70 85 15 4 1 Example 3 A 3 DPHA/ .sup.74.5 534/ 27/ BS577 72 1000 30 85 15 4 1 M9050 420 40 Example 4 A 3 DPHA/ 75 534/ 27/ BS577 72 1000 30 85 15 4 1 M9050 400 40 Example 5 A 1.5 DPHA 74 534 .sup.13.5 BS577 72 1000 85 85 15 4 1 Example 6 A 8 DPHA 74 534 72 BS577 72 1000 20 85 15 4 1 Example 7 B 3 DPHA 74 534 27 BS577 72 1000 70 85 15 4 1 Example 8 A 3 DPHA 74 534 27 BS577 72 1000 70 85 15 4 2.5 Example 9 A 3 DPHA 74 534 27 BS577 72 1000 70 85 15 4 0.1 Example 10 A 3 DCPA 76 303 27 BS577 72 1000 70 85 15 4 1 Example 11 A 3 DPHA 74 534 27 BS577 72 1000 70 85 15 4 1 Example 12 A 3 DPHA 74 534 27 BS577 72 1000 70 55 45 4 1 Example 13 A 3 DPHA 74 534 27 BS577 72 1000 70 70 30 4 1 Example 14 A 3 DPHA 74 534 27 BS577 72 1000 70 85 (*1) 15 4 1 Example 15 B 3 DPHA 74 534 27 BS577 72 1000 70 70 30 4 1 Comparative A 3 PETA 69 298 23 85 15 4 1 Example 1 Comparative B 3 BS577 72 1000 97 85 15 4 1 Example 2 Comparative DPHA 74 534 30 BS577 72 1000 70 85 15 4 1 Example 3 Comparative A 3 DPHA 74 534 27 BS577 72 1000 70 85 15 4 1 Example 4 Comparative A 3 PETA 88 298 27 HOP 65 144 70 85 15 4 1 Example 5 Comparative B 3 UN904/ 80 4900/ 50/47 85 15 4 1 Example 6 DPHA40H 7000 Reference A 3 DPHA 74 534 27 BS577 72 70 85 15 4 5 Example 1 Reference B 3 DPHA 74 534 27 BS577 72 1000 70 45 55 4 1 Example 2 Reference A 3 DPHA 74 534 27 BS577 72 1000 70 100 0 4 1 Example 3 Reference A 3 DPHA 74 534 27 BS577 72 1000 70 0 100 4 1 Example 4 Reference C 3 DPHA 74 534 27 BS577 72 1000 70 85 15 4 1 Example 5 Reference D 3 DPHA 74 534 27 BS577 72 1000 70 85 15 4 1 Example 6 Reference A 3 V802 74 1000 27 BS577 72 1000 70 70 30 4 1 Example 7 Reference A 3 DPHA 74 534 27 EBECRYL 71 600 70 85 15 4 1 Example 8 8210 Reference A 3 DPHA 74 534 27 UX-2204 80 13000 70 85 15 4 1 Example 9 Reference A 3 DPHA 74 534 27 EBECRYL 72 6000 70 85 15 4 1 Example 10 885 (*1): Content of ethyl acetate

(30) TABLE-US-00002 TABLE 2 Surface resistance Interference Haze Pencil Transmittance Substrate value (/) pattern (%) Adhesion hardness (%) Example 1 TAC 2 10.sup.9 Absent 0.3 Good 3H 92 Example 2 TAC 2 10.sup.9 Absent 0.3 Good 3H 92 Example 3 TAC 2 10.sup.9 Absent 0.3 Good 3H 92 Example 4 TAC 1 10.sup.8 Absent 0.3 Good 3H 92 Example 5 TAC 9 10.sup.9 Absent 0.3 Good 3H 92 Example 6 TAC 5 10.sup.8 Absent 0.3 Good 3H 92 Example 7 TAC 8 10.sup.9 Absent 0.3 Good 3H 92 Example 8 TAC 9 10.sup.8 Absent 0.3 Good 3H 92 Example 9 TAC 9 10.sup.9 Absent 0.3 Good 3H 92 Example 10 TAC 2 10.sup.8 Absent 0.3 Good 3H 92 Example 11 TAC 2 10.sup.9 Absent 0.3 Good 3H 92 Example 12 TAC 2 10.sup.9 Absent 0.3 Good 3H 92 Example 13 TAC 2 10.sup.9 Absent 0.3 Good 3H 92 Example 14 TAC 1 10.sup.9 Absent 0.3 Good 3H 92 Example 15 TAC 2 10.sup.9 Absent 0.3 Good 3H 92 Comparative TAC .sup.5 10.sup.11 Absent 0.3 Good 3H 92 Example 1 Comparative TAC .sup.8 10.sup.11 Present 0.3 Poor 3H 92 Example 2 Comparative TAC OVER Present 0.3 Poor 3H 92 Example 3 Comparative PET .sup.8 10.sup.11 Present 0.5 Poor 3H 92 Example 4 Comparative TAC .sup.5 10.sup.11 Absent 0.3 Good H 92 Example 5 Comparative TAC .sup.8 10.sup.12 Present 0.3 Poor H 92 Example 6 Reference TAC 7 10.sup.5 Absent 1.5 Good 3H 89 Example 1 Reference TAC .sup.8 10.sup.12 Present 0.3 Poor 3H 92 Example 2 Reference TAC 8 10.sup.8 Absent 1.5 Good 3H 89 Example 3 Reference TAC OVER Present 0.3 Poor 3H 92 Example 4 Reference TAC .sup.5 10.sup.11 Absent 0.3 Good 3H 92 Example 5 Reference TAC .sup.5 10.sup.11 Absent 0.3 Good 3H 92 Example 6 Reference TAC .sup.8 10.sup.12 Present 0.3 Poor 3H 92 Example 7 Reference TAC 2 10.sup.9 Absent 1.5 Good 3H 89 Example 8 Reference TAC OVER Present 0.3 Poor H 92 Example 9 Reference TAC .sup.5 10.sup.11 Absent 0.3 Good H 92 Example 10

(31) Table 2 shows that the optical layered bodies of Examples of the present invention had excellent antistatic, optical characteristics, hardness, adhesion, and interference fringe prevention performance. On the other hand, none of the optical layered bodies of Comparative Examples was good in any of antistatic properties, optical characteristics, hardness, adhesion, or interference fringe prevention performance.

(32) The optical layered body of Reference Example 1 had a high water content in the resin composition, and was poor in optical characteristics. The optical layered body of Reference Example 2 had a large amount of hydrophilic solvent used, and was poor in antistatic properties and adhesion. The optical layered body of Reference Example 3 was poor in optical characteristics because the hydrophilic solvent was not used. The optical layered body of Reference Example 4 was poor in antistatic properties and adhesion because the hydrophobic solvent was not used. The optical layered body of Reference Example 5 included a quaternary ammonium salt-containing polymer having a high weight-average molecular weight, and was poor in antistatic properties. The optical layered body of Reference Example 6 included a quaternary ammonium, salt-containing polymer having a low weight-average molecular weight, and was poor in antistatic properties. The optical layered body of Reference Example 7 included a binder resin in which a monomer component had a high weight-average molecular weight, and was poor in antistatic properties and adhesion. The optical layered body of Reference Example 8 included a binder resin in which an oligomer component (urethane oligomer) had a low weight-average molecular weight, and was poor in optical characteristics. The optical layered body of Reference Example 9 included a binder resin in which an oligomer component (urethane oligomer) had a high weight-average molecular weight, and the optical layered body was poor in antistatic properties, adhesion, and hardness. The optical layered body of Reference Example 10 was poor in antistatic properties and hardness because urethane oligomer was not used as the oligomer component in the binder resin.

INDUSTRIAL APPLICABILITY

(33) The optical layered body of the present invention is suitably applicable to cathode-ray tube (CRT) display devices, liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescence displays (ELDs), field emission displays (FEDs), touch panels, electronic paper, and the like.

REFERENCE SIGN LIST

(34) 1 Triacetylcellulose substrate 2 Resin composition 3 Quaternary ammonium salt-containing polymer 4 Resin composition (penetration portion) 5 Resin composition (unpenetrated portion) 6 Hard coat layer 7 Blended layer 8 Low-refractive index layer