JPH08244051A - Optical sheet and production thereof - Google Patents

Abstract

PURPOSE: To obtain an optical sheet markedly enhanced in the resistance against an aromatic hydrocarbon solvent, a ketone type solvent and a halogen-containing solvent and still more enhanced in heat resistance and surface hardness while keeping the beneficial points of a norbornene resin. CONSTITUTION: An optical sheet is composed of a norbornene resin film crosslinked by an internal or external crosslinking means, especially, a cast film of a compsn. wherein the wt. ratio of a norbornene resin and a crosslinking agent is 99:1-50:50. The crosslinking agent is pref. org. peroxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes an electrode substrate for a liquid crystal cell of a liquid crystal display device, a protective plate for a polarizing element film or a retardation element film, a film with a transparent electrode for a touch panel, and an electromagnetic wave shield plate for a CRT. Excellent optical isotropy, transparency, moisture / water resistance, acid / alkali resistance, polar solvent resistance, aromatic hydrocarbon solvent / ketone solvent / halogen-containing solvent resistance, heat resistance, and surface hardness, suitable for optical applications And an optical sheet and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, polycarbonate films, polyarylate films, polyether sulfone films, and polysulfone films have been used as optical base sheets. This is because these films have excellent optical isotropy and transparency and have some heat resistance. Among these films, the polycarbonate film, which is advantageous in terms of cost, is most widely used.
The polyethersulfone film and the polysulfone film have the highest heat resistance among these four types, but have the disadvantage of being slightly colored, and are expensive. The polyarylate film is in the middle position between the two.

Since only such a substrate sheet (polycarbonate film, polyarylate film, polyether sulfone or polysulfone film) lacks properties such as air permeability, solvent resistance and transparent electrode adhesion, one side of these films Alternatively, it has been proposed to laminate an air permeable resin layer or a crosslinkable resin cured product layer on both sides. For example, Japanese Patent Application Laid-Open No. 63-7 filed by the applicant.
No. 1829 (Electrode substrate for liquid crystal display panel having a layer structure of an optically isotropic substrate sheet layer / anchor coat layer / air-permeable resin layer / crosslinkable resin cured material layer) and JP-A-4-159518.
Gazette (Adhesion of two or more unit laminated sheets having a layer structure of optically isotropic substrate sheet layer / air-permeable resin layer / crosslinkable resin cured material layer so that the crosslinkable resin cured material layer becomes both outermost layers. Electrode substrate for a liquid crystal display panel having a structure in which it is adhered via an agent layer).

Recently, attention has been paid to the use of a film of a norbornene-based resin belonging to amorphous polyolefin as an optical base sheet.

For example, on pages 41-44 of "Plastics, July 1987 (Vol. 38, No. 7)", there is an article entitled "Polyolefin resin-new polymer for optical disks" APO "" relating to amorphous polyolefin. , "Functional Materials, December 1994 (Vol. 14, No. 12)"
Articles titled "Application of ARTON to transparent conductive film" are published on pages 40 to 51 of the above.

Further, in Japanese Patent Application Laid-Open No. 4-361230, which is a joint application of the present applicant and Nippon Zeon Co., Ltd., a liquid crystal having a film obtained by stretching and aligning a thermoplastic saturated norbornene resin sheet as a birefringent layer. There is a disclosure of a phase plate for a display, and Japanese Patent Laid-Open No. 6-511117, which is also a joint application of both, discloses a polarizing film for a liquid crystal display in which a thermoplastic saturated norbornene-based resin sheet is laminated as a protective layer on at least one surface of a polarizing film. Is disclosed. Furthermore, the present applicant has filed numerous applications regarding the use of various polymer films including amorphous polyolefin (bicycloolefin-based polyolefin, norbornene-based resin) as a base film such as an electrode substrate.

[0007]

A film of norbornene-based resin belonging to amorphous polyolefin is more transparent than a base sheet such as a polycarbonate film, a polyarylate film, a polyethersulfone film or a polysulfone film which has been generally used conventionally. And has a small birefringence, and has resistance to a polar solvent (dimethylacetamide or N-methylpyrrolidone) for forming an alignment film.

However, although the above norbornene-based resins have resistance to moisture and water, resistance to acid and alkali, and resistance to polar solvents such as dimethylacetamide, N-methylpyrrolidone and alcohol, they are aromatic hydrocarbon solvents. (Benzene, toluene, xylene, etc.), ketone solvents (methyl ethyl ketone, etc.), halogen-containing solvents (chloroform, methylene chloride, etc.) There is a problem in that it has no resistance to various casting film forming solvents. In other words, the advantage that casting film formation is possible is
It is disadvantageous in terms of resistance to general-purpose solvents.

If the advantages of the norbornene-based resin, that is, high transparency, low birefringence, high heat resistance, casting film forming property, moisture / water resistance, acid / alkali resistance, polar solvent resistance are not impaired, If it is possible to impart resistance to general-purpose solvents such as hydrocarbon solvents, ketone solvents, halogen-containing solvents, etc., and further improve heat resistance and surface hardness, its suitability as an optical sheet is extremely preferable. Becomes

Under such circumstances, the present invention remarkably improves the resistance to the aromatic hydrocarbon solvent, the ketone solvent and the halogen-containing solvent while maintaining the advantages of the norbornene resin, and further, the heat resistance. It is an object of the present invention to provide an optical sheet having improved properties and surface hardness, and a method for producing the same.

[0011]

The optical sheet of the present invention comprises a norbornene-based resin (A) film that has been crosslinked by taking internal or external crosslinking means. It is particularly preferable that the film is a cast film.

More practically, the above-mentioned optical sheet of the present invention is a casting film of a composition in which the weight ratio of the norbornene resin (A) to the crosslinking agent (B) is 99: 1 to 50:50. It consists of a film.

Correspondingly, the method for producing an optical sheet of the present invention is a solvent solution of the composition of the norbornene resin (A) and the crosslinking agent (B) in a weight ratio of 99: 1 to 50:50. Is cast on a support (S), dried and heat-treated.

The norbornene-based resin (A) is, for example, a resin obtained by hydrogenating a ring-opening (co) polymer of a norbornene-based monomer after polymer modification such as addition of maleic acid or addition of cyclopentadiene as necessary. Examples thereof include resins obtained by addition-type copolymerizing norbornene-based monomers with olefin-based monomers such as ethylene and α-olefin.

Here, as the norbornene-based monomer,
Norbornene, alkyl or / and alkylidene-substituted norbornene (5-methyl-2-norbornene,
5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, etc.), polar group substituents of these halogens, dicyclopentadiene, 2, 3-dihydrodicyclopentadiene, dimethanooctahydronaphthalene or its alkyl or / and alkylidene substituents or polar group substituents such as halogens, adducts of cyclopentadiene and tetrahydroindene, etc., cyclopentadiene 3- to 4-mer, etc. Can be given.

The norbornene-based resin (A) has a number average molecular weight (measured by the GPC method using a toluene solvent) of, for example, 25,000 to 1,000 in consideration of physical properties and moldability.
A value of about 00, preferably about 30,000 to 80,000 is suitable.

Commercially available products of the norbornene resin (A) include "Zeonex" manufactured by Nippon Zeon Co., Ltd., "APO" manufactured by Mitsui Petrochemical Co., Ltd., and "ARTON" manufactured by Japan Synthetic Rubber Co., Ltd. .

The optical sheet of the present invention comprises a norbornene-based resin (A) film (particularly a cast film) which has been crosslinked by taking internal or external crosslinking means. Internal crosslinking is carried out by adding a crosslinking agent (B) as described in detail below. External crosslinking is carried out by irradiation with ultraviolet rays, electron beams or γ-rays, and in the case of ultraviolet crosslinking, a photosensitizer is optionally added. From the industrial point of view, the former internal cross-linking means is often adopted, and therefore the case of the internal cross-linking means mainly using the cross-linking agent (B) will be described below.

Examples of the cross-linking agent (B) include organic peroxides such as hydroxy peroxide, diacyl peroxide, peroxydicarbonate, peroxyester, peroxymonocarbonate, dialkyl peroxide, ketone peroxide, and peroxyketal. Is particularly important, in addition, melamine compound-based crosslinking agent, phenol compound-based crosslinking agent, epoxy compound-based crosslinking agent, isocyanate compound-based crosslinking agent, urethane-based crosslinking agent, polyamine-based crosslinking agent, metal chelate compound-based crosslinking agent, organic Various crosslinking agents such as titanate-based crosslinking agent, organic zirconium-based crosslinking agent, organic silane-based crosslinking agent, carboxylic acid or acid anhydride-based crosslinking agent, metal salt-based crosslinking agent, amine or aziridine-based crosslinking agent are also used. .

The weight ratio of the norbornene resin (A) to the crosslinking agent (B) in the composition is 99: 1 to 50:50,
The composition is preferably mixed in a ratio of 98: 2 to 60:40.

Then, a solvent solution of this composition is added to the support (S).
The desired optical sheet is obtained by casting on top, drying and heat treatment. As the solvent, a common solvent between the norbornene-based resin (A) and the crosslinking agent (B), for example,
Aromatic hydrocarbon solvents (benzene, toluene, xylene, etc.), ketone solvents (methyl ethyl ketone, etc.), halogen-containing solvents (chloroform, methylene chloride, etc.) are used alone or as a mixed solvent. The solid content concentration of the liquid used for the casting film formation is often set to about 1 to 50% by weight.

As the support (S), a biaxially oriented polyester (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate) film, a biaxially oriented polypropylene film, or the like is preferably used. Since the smoothness of the surface of the support film can be arbitrarily selected, the surface roughness is ± 0.1 μm or less, so that the smoothness is intentionally increased to prevent glare and improve the incident rate of incident light. It is possible to use those having arbitrary smoothness or roughness, even those having random fine irregularities or lens-like fine irregularities.

As the support (S), other single-layer or multi-layer optical film itself may be used. For example, a support (S) provided with an air-permeable layer or / and a cured resin layer of a crosslinkable resin, a conventional base sheet without a support (S) or an air-permeable layer or / and a crosslinkable resin. A cured resin layer or the like can be used as the above-mentioned support (S). As the support (S), a metal endless belt or drum may be used.

The support (S) can be peeled and removed at an appropriate stage later, and depending on the application, it can be used as an optical sheet with the support (S) attached.

There is no particular limitation on the thickness of the cast film of the composition thus obtained, and the thickness can be any thickness (for example, about 1 to 200 μm or more). Since an extremely thick film is difficult to manufacture due to the use of the casting film forming method, two or more casting film forming films of the above composition may be laminated and adhered for the purpose of particularly increasing the thickness. .

The cast film formed from the above composition is used for optical applications either as a single layer or in the form of a laminate with another optical film or layer. Here, the other optical film or layer is a conventionally used base film, an organic or inorganic air-permeable layer (polyvinyl alcohol or a copolymer modified product / graft / polymer alloy or ethylene content of 15 to 50). Vinyl alcohol type resin layer such as ethylene-vinyl alcohol copolymer of 50 mol%, vinylidene chloride type resin layer, high acrylonitrile type resin layer, metal oxide layer, metal complex oxide layer, etc.), crosslinkable resin cured product layer (A thermosetting resin layer such as a phenoxy ether resin, an ultraviolet curing resin layer, an electron beam curing resin layer), a polarizing element film,
It is a retardation film or a combination thereof.

The cast film of the above composition may be directly cast on the cast film or via an anchor coating layer.
A transparent electrode such as ITO can be formed.

The optical sheet of the present invention comprising a cast film of the above composition has optical isotropy, transparency, moisture / water resistance, acid / alkali resistance, solvent resistance (whether polar or non-polar). However, the optical sheet is uniaxially stretched or biaxially stretched by controlling the uniaxial stretching ratio to give a retardation film or It can also be used as an electrode substrate that also serves as a retardation film.

The optical sheet of the present invention is, for example, an electrode substrate of a liquid crystal cell constituting a liquid crystal display device, a protective film of a polarizing element film, a protective plate of a retardation film, an electrode substrate also serving as a polarizing plate, and a phase plate also serving as Electrode substrate, film with transparent electrode for touch panel (including those used not only on the polarizing plate but also under the polarizing plate), electromagnetic wave shield plate for CRT, backlight, light guide plate, color filter, optical card It is useful for applications such as, optical tapes and optical disks.

[0030]

The optical sheet of the present invention is a norbornene-based resin (A) film which has been crosslinked by taking an internal or external crosslinking means, particularly a norbornene-based resin (A).
Since it is composed of a cast film of a composition containing (B), the advantage of the norbornene-based resin film is that it has high transparency, low birefringence, high heat resistance, cast film formation, and moisture / water resistance. , While maintaining acid resistance, alkali resistance, and polar solvent resistance as it is, resistance to aromatic hydrocarbon solvents, ketone solvents, and halogen-containing solvents, which are the drawbacks, is remarkably improved, and heat resistance and surface hardness are further improved. improves.

[0031]

EXAMPLES The present invention will be further described with reference to examples. Hereinafter, "parts" and "%" are based on weight except "%" of the total light transmittance. The surface roughness was measured with a non-contact type surface roughness meter utilizing light interference.

Example 1 30 parts of "Zeonex" manufactured by Nippon Zeon Co., Ltd. as an example of the norbornene-based resin (A) was dissolved in 200 parts of toluene, and this solution was used as an example of the peroxide-based crosslinking agent (B). 2,4-dichlorobenzoyl peroxide (1.5 parts) and 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane (2 parts) were added and mixed to prepare a composition solution.

Then, a solution of this composition was added to a thickness of 100 μm.
m, surface roughness average 0.006 μm, maximum 0.04 μm cast on a smooth surface of a support (S) consisting of a biaxially stretched polyethylene terephthalate film not subjected to corona discharge treatment,
After drying with hot air at a temperature of 50 to 110 ° C., it was cured at a temperature of 120 ° C. for 25 minutes and further heat-treated at a temperature of 140 ° C. for 15 minutes. By removing the support (S) by peeling, the thickness 9
An optical film of 5 μm was obtained.

The characteristic values of this optical film were as follows. The acid / alkali resistance and solvent resistance were evaluated by observing the changes when they were impregnated at room temperature for 1 day. Transparency (total light transmittance, ASTM D1003): 96% Retardation value (633 nm): 2 nm Heat resistance (glass transition point by DSC): 165 ° C Chemical resistance: 5% HCl (no abnormality), 3% KOH ( Aromatic hydrocarbon solvent resistance: benzene (no abnormality), toluene (no abnormality), xylene (no abnormality) Ketone solvent resistance: methyl ethyl ketone (no abnormality) Halogen-containing solvent resistance: chloroform (no abnormality), methylene chloride (No abnormality) Polar solvent resistance: N-methylpyrrolidone (No abnormality), Dimethylacetamide (No abnormality), Isopropanol (No abnormality), Ethanol (No abnormality), Methanol (No abnormality) Pencil hardness (JIS K5401): 3H

Comparative Example 1 A solution was prepared by dissolving 30 parts of "ZEONEX" manufactured by Nippon Zeon Co., Ltd. as an example of the norbornene-based resin (A) in 200 parts of toluene (peroxide-based crosslinking agent (B) Not added). This solution was cast on the smooth surface of the same support (S) as in Example 1 and sufficiently dried with hot air at a temperature of 50 to 110 ° C for a long time. As a result, an optical film having a thickness of 95 μm was obtained.

The characteristic values of this optical film were as follows. Transparency (total light transmittance, ASTM D1003): 96% Retardation value (633 nm): 2 nm Heat resistance (glass transition point by DSC): 145 ° C Chemical resistance: 5% HCl (no abnormality), 3% KOH ( No abnormality) Aromatic hydrocarbon solvent resistance: Benzene (dissolution), Toluene (dissolution), Xylene (dissolution) Ketone solvent resistance: Methyl ethyl ketone (dissolution) Halogen-containing solvent resistance: Chloroform (dissolution), methylene chloride (dissolution) Polar solvent Resistance: N-methylpyrrolidone (no abnormality), dimethylacetamide (no abnormality), isopropanol (no abnormality), ethanol (no abnormality), methanol (no abnormality) Pencil hardness (JIS K5401): H

Example 2 Retardation value as substrate film 6 nm, thickness 1
A 5 μm thick polycarbonate film is cast on one side of a water-soluble polyester urethane anchor coating agent with a solid content of 5%, dried and heat treated to obtain a thickness.
An anchor coating layer of 0.5 μm was formed. Then, from above the anchor coating layer, a methylol melamine-based cross-linking agent ("Sumitec M-3" manufactured by Sumitomo Chemical Co., Ltd.) was added to an aqueous solution of polyvinyl alcohol N-methylol acrylamide-acrylic acid graft polymer having a concentration of 12%. Was cast at a solid content ratio of 3% and dried at 70 to 90 ° C. to form an air-permeable resin layer having a thickness of 8 μm.

Similarly, an anchor coating layer having a thickness of 0.5 μm and an air-permeable resin layer having a thickness of 8 μm were formed in this order on the other surface of the polycarbonate film. As a result, a laminated film having a layer structure of air-permeable resin layer / anchor coating layer / polycarbonate film / anchor coating layer / air-permeable resin layer was obtained.

A solution of the composition of Example 1 was cast on one surface of this laminated film and dried at a temperature of 50 to 110 ° C.
Cured at a temperature of 120 ° C for 25 minutes, then at a temperature of 140 ° C
Heat treatment for 15 minutes in norbornene resin (A) and cross-linking agent
A layer having a thickness of 8 μm was formed from the composition of (B).
Similarly, on the other surface of the laminated film, a thickness of 8 μm composed of the composition of the norbornene resin (A) and the crosslinking agent (B)
A layer of m 2 was formed. .

The symmetrical laminated film thus obtained is useful for various optical applications such as an electrode substrate of a liquid crystal cell of a liquid crystal display device.

Example 3 In place of the polycarbonate film, the optical film having a thickness of 95 μm obtained in Example 1 was used as a substrate film,
In the same manner as in Example 2, a laminated film having a layer structure of air-permeable resin layer / anchor coating layer / optical film of Example 1 / anchor coating layer / air-permeable resin layer was obtained. The thicknesses of the anchor coating layer and the air-permeable resin layer were the same as in Example 2.

Next, 40 parts of phenoxy ether resin and 40 parts of methyl ethyl ketone were directly applied to one surface of this laminated sheet.
Part, 20 parts of cellosolve acetate, 75 parts of an adduct of tolylene diisocyanate and trimethylolpropane
% Toluene solution ("Coronate L" manufactured by Nippon Polyurethane Industry Co., Ltd.) 40 parts by casting,
After drying at 0 to 90 ° C., it was cured at 140 ° C. for 20 minutes to form a cured crosslinkable resin layer having a thickness of 11 μm. Similarly, a cured crosslinkable resin layer having a thickness of 11 μm was formed on the other surface of this laminated sheet.

The symmetrical laminated film thus obtained is also useful for various optical applications such as an electrode substrate of a liquid crystal cell of a liquid crystal display device.

Example 4 Norbornene resin (A) 50 of a type different from that of Example 1
Parts were dissolved in 300 parts of xylene, and 1 part of benzoyl peroxide and 1 part of dicumyl peroxide as an example of the peroxide-based cross-linking agent (B) were added and mixed to this solution to prepare a composition solution.

Then, a solution of this composition was cast on the smooth surface of the same support (S) as in Example 1, dried at a temperature of 50 to 110 ° C., and then cured at a temperature of 140 ° C. for 25 minutes, and further heated at a temperature of 140 ° C. Heat treatment was performed at 150 ° C. for 15 minutes. By peeling and removing the support (S), an optical film having a thickness of 120 μm was obtained.

The characteristic values of this optical film were as follows. Transparency (total light transmittance, ASTM D1003): 94% Retardation value (633 nm): 2 nm Heat resistance (glass transition point by DSC): 182 ° C Chemical resistance: 5% HCl (no abnormality), 3% KOH ( Aromatic hydrocarbon solvent resistance: benzene (no abnormality), toluene (no abnormality), xylene (no abnormality) Ketone solvent resistance: methyl ethyl ketone (no abnormality) Halogen-containing solvent resistance: chloroform (no abnormality), methylene chloride (No abnormality) Polar solvent resistance: N-methylpyrrolidone (No abnormality), Dimethylacetamide (No abnormality), Isopropanol (No abnormality), Ethanol (No abnormality), Methanol (No abnormality) Pencil hardness (JIS K5401): 4H

Comparative Example 2 50 parts of the norbornene resin (A) of Example 4 was mixed with xylene 3
A solution was prepared by dissolving it in 00 parts (peroxide type crosslinking agent
(B) is not added). This solution was applied to the same support as in Example 4.
It was cast on the smooth surface of (S) and dried sufficiently at a temperature of 50 to 110 ° C. for a long time. As a result, an optical film having a thickness of 123 μm was obtained.

The characteristic values of this optical film were as follows. Transparency (total light transmittance, ASTM D1003): 94% Retardation value (633 nm): 2 nm Heat resistance (glass transition point by DSC): 167 ° C Chemical resistance: 5% HCl (no abnormality), 3% KOH ( No abnormality) Aromatic hydrocarbon solvent resistance: Benzene (dissolution), Toluene (dissolution), Xylene (dissolution) Ketone solvent resistance: Methyl ethyl ketone (dissolution) Halogen-containing solvent resistance: Chloroform (dissolution), methylene chloride (dissolution) Polar solvent Resistance: N-methylpyrrolidone (no abnormality), dimethylacetamide (no abnormality), isopropanol (no abnormality), ethanol (no abnormality), methanol (no abnormality) Pencil hardness (JIS K5401): 2H

[0049]

As described in the section of the operation, the optical sheet of the present invention is a norbornene-based resin (A) film crosslinked by taking internal or external crosslinking means, particularly a norbornene-based resin. (A) comprises a film formed by casting a composition containing a cross-linking agent (B), and therefore has the advantage of a norbornene-based resin film, that is, high transparency, low birefringence,
High heat resistance, cast film formation, moisture / water resistance, acid / alkali resistance, and polar solvent resistance are maintained, but resistance to aromatic hydrocarbon solvents, ketone solvents, and halogen-containing solvents, which are the drawbacks, is maintained. Notably, the heat resistance and surface hardness are further improved.

The improvement in heat resistance and surface hardness means that when a sheet having the above-mentioned optical sheet is provided with a transparent electrode and is used as an electrode substrate, the pattern electrode and the outer lead of the control IC are packaged together. It contributes to prevent any trouble when the thermocompression bonding is performed with the anisotropic conductive sheet interposed between the two.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B29L 11:00 (72) Inventor Hirotoshi Terui 1-4-16 Nihonbashi Bakurocho, Chuo-ku, Tokyo Fujimori Industry Incorporated (72) Inventor Kenji Hashimoto 1-4-16 Nihonbashi Bakurocho, Chuo-ku, Tokyo Fujimori Industry Co., Ltd.

Claims (5)

[Claims] 1. An optical sheet comprising a norbornene-based resin (A) film cross-linked by taking internal or external cross-linking means. 2. The optical sheet according to claim 1, which is a cast film-forming film. 3. The optical sheet according to claim 1, which comprises a cast film formed of a composition having a weight ratio of the norbornene resin (A) to the crosslinking agent (B) of 99: 1 to 50:50. 4. The cross-linking agent (B) is an organic peroxide.
The optical sheet described. 5. A solvent solution of a composition having a weight ratio of norbornene-based resin (A) to crosslinking agent (B) of 99: 1 to 50:50 is cast on a support (S), dried and heat treated. A method for producing an optical sheet, comprising: