CN106959477B

CN106959477B - Optical film, method for producing optical film, polarizing plate, and image display device

Info

Publication number: CN106959477B
Application number: CN201710010492.6A
Authority: CN
Inventors: 岩间翔太; 高木隆裕; 梅田博纪; 田坂公志
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 2016-01-08
Filing date: 2017-01-06
Publication date: 2021-01-22
Anticipated expiration: 2037-01-06
Also published as: CN106959477A; JP2017122855A; KR20170083485A; TW201736877A

Abstract

The invention relates to an optical film, a method for manufacturing the optical film, a polarizing plate and an image display device. The invention provides an optical film with good conveying performance and low haze. The optical film of the present invention is an optical film containing a cycloolefin resin, fine particles, and a surface conditioner, wherein the surface conditioner contains at least one of a silicone material, a fluorine-based material, a vinyl-based material, and an acrylic-based material, and the surface roughness Ra of the surface having a high surface roughness Ra is in the range of 3.0 to 50.0nm on both surfaces of the film.

Description

Optical film, method for producing optical film, polarizing plate, and image display device

Technical Field

The invention relates to an optical film, a method for manufacturing the optical film, a polarizing plate and an image display device. The present invention particularly relates to an optical film having good transportability and low haze, a method for producing the optical film, a polarizing plate and an image display device provided with the optical film.

Background

Conventionally, a polarizing plate including a polarizer, a protective film, and the like is mounted on an image display device such as a television, a notebook computer, and a smartphone.

As a material constituting the protective film, for example, cellulose ester resin, polycarbonate, cycloolefin resin, and the like are known. Among these, a cycloolefin resin is preferably used from the viewpoint of having high heat resistance and moisture resistance.

In recent years, optical members used in image display devices have been reduced in thickness, and cycloolefin resin films have also been used in a thin state. In the production of a cycloolefin resin film as a film and in the production of a polarizing plate using the film, the cycloolefin resin film may be conveyed in a state where a protective film is bonded to one of both surfaces of the film in order to maintain the film quality.

However, if the protective film is used, there is a problem that when the protective film has a defect, the defect is transferred to the cycloolefin resin film. Further, there is a problem that the cycloolefin resin film is deformed by thermal correction performed at the time of manufacturing the polarizing plate due to a difference in thermal expansion coefficient between the protective film and the cycloolefin resin film.

Therefore, when the polarizing plate is produced by transporting the cycloolefin resin film without the protective film being bonded thereto, unevenness, wrinkles, cracks, and the like occur on the surface of the cycloolefin resin film during transportation, and the yield of the polarizing plate is significantly reduced. This is because, since the cycloolefin resin film does not slip on the conveying roller, the conveying tension applied to the cycloolefin resin film becomes excessive.

As a method for sliding the cycloolefin resin film on the conveying roller, a method is known in which silica fine particles are added to the cycloolefin resin film to adjust the surface roughness Ra. However, in the case of the cycloolefin resin, in order to make the film surface have the predetermined surface roughness Ra, a large amount of silica fine particles need to be added, and thus haze is increased due to scattering or the like of light incident to the film. When the cycloolefin resin film having an increased haze is used for an image display device, a problem occurs in that the front contrast is decreased, and the quality is deteriorated. Further, it is considered that the film can be slid with respect to the transport roller by providing a hard coat layer containing fine metal particles on the film surface (for example, see patent document 1), but since the hard coat layer is laminated on the film surface, the thickness of the entire film increases, and the haze increases.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2007-219485

Disclosure of Invention

The present invention has been made in view of the above problems and circumstances, and an object of the present invention is to provide an optical film having good transportability and low haze, a method for producing the optical film, a polarizing plate and an image display device each including the optical film.

As a result of investigations on the causes of the above problems and the like in order to solve the above problems according to the present invention, it has been found that an optical film having good transportability and low haze can be provided by including fine particles and a surface conditioner in an optical film containing a cycloolefin resin and setting the surface roughness Ra of a surface having a high surface roughness Ra in a predetermined numerical range on both surfaces of the optical film.

That is, the problem according to the present invention is solved by the following means.

1. An optical film characterized by containing a cycloolefin resin, fine particles and a surface modifier,

the surface conditioner contains at least one of a silicone material, a fluorine material, a vinyl material and an acrylic material,

the surface roughness Ra of the surface with high surface roughness Ra in the two surfaces of the film is within the range of 3.0-50.0 nm.

2. The optical film according to claim 1, wherein,

the surface roughness Ra of the surface with low surface roughness Ra in the two surfaces of the film is within the range of 2.0-20.0 nm,

the difference in surface roughness Ra between both surfaces of the film is 1.0nm or more.

3. The optical film according to claim 1 or 2, wherein the fine particles contain a silicon compound.

4. A method for producing an optical film, which is characterized by comprising the step of producing the optical film according to any one of items 1 to 3,

the resin composition is produced by a solution casting method using two or more solvents.

5. A polarizing plate is characterized by comprising:

polarizer and

the optical film according to any one of items 1 to 3.

6. The polarizing plate according to claim 5, wherein the polarizer is bonded to a surface having a low surface roughness Ra of both surfaces of the optical film.

7. An image display device comprising the optical film according to any one of items 1 to 3.

According to the present invention, an optical film having good transportability and low haze, a method for producing the optical film, a polarizing plate and an image display device provided with the optical film can be provided.

The expression mechanism or action mechanism of the effect of the present invention is not clearly understood, but is presumed as follows.

In general, when an optical film is produced by a solution casting method in which a coating material of a composition containing an optical film is cast onto a support and a solvent is dried from the film-like material to obtain a film, it is preferable that a low-boiling point solvent be contained in the coating material as a good solvent from the viewpoint of peelability at the time of peeling the film-like material from the support.

It is presumed that when an optical film is produced by this method, the fine particles and the surface conditioner form an associated body in the coating material or the film-like material, and the associated body has high affinity for the good solvent. Therefore, in the process of drying the film-like material cast on the support, the associated body moves to the surface of the film-like material on the air interface side together with the good solvent volatilized from the film-like material, and is immobilized in this state to produce the optical film. This makes it possible to cause the fine particles to be unevenly distributed on one surface of the optical film together with the surface conditioner, and selectively chap one surface (surface on the air interface side) of both surfaces of the optical film, thereby exhibiting remarkable slidability. The optical film has improved transportability by imparting slidability thereto, and can be produced in high yield while suppressing the occurrence of surface irregularities and wrinkles without providing a protective film or a hard coat layer. Further, since the surface conditioner contains fine particles together with the surface conditioner, the fine particles can be biased to one surface of the optical film to selectively impart slidability, and therefore the content of the fine particles can be reduced, and the optical film having low haze can be produced. Further, by providing the one surface of the optical film with slidability also in the winding step in the production of the optical film, the occurrence of winding displacement and the like can be suppressed.

Detailed Description

The optical film of the present invention is an optical film containing a cycloolefin resin, fine particles, and a surface conditioner, wherein the surface conditioner contains at least one of a silicone material, a fluorine material, a vinyl material, and an acrylic material, and the surface roughness Ra of a surface having a high surface roughness Ra is in a range of 3.0 to 50.0nm on both surfaces of the film. The features are common to or correspond to the features of the respective claims.

In the present invention, it is preferable that the surface roughness Ra of the surface with low surface roughness Ra of both surfaces of the film is in the range of 2.0 to 20.0nm, and the difference between the surface roughness Ra of both surfaces of the film is 1.0nm or more. Accordingly, when a polarizer is bonded to the surface having the low surface roughness Ra to produce a polarizing plate, since the number of irregularities is smaller than that of the other surface, a gap is less likely to be formed at the bonding interface with the polarizer, and scattering of light can be suppressed, and problems such as light leakage can be effectively suppressed when the polarizer is mounted on an image display device. Further, since the surface roughness Ra of the surface having a low surface roughness Ra is within the above range, the surface also exhibits slidability, and the conveyance property can be further improved. Further, the haze value can be kept low and the transportability of the optical film can be improved by making the surface roughness Ra of both surfaces of the film different.

In the present invention, the fine particles preferably contain a silicon compound. This improves the affinity between the fine particles and the surface conditioner, and enables the fine particles to move more reliably into the film during the formation of the optical film, thereby more reliably obtaining good transportability.

The method for producing an optical film of the present invention is a method for producing an optical film for producing the optical film, and is characterized by being produced by a solution casting method using two or more solvents. Thus, an optical film having good transportability and low haze can be produced.

The polarizing plate of the present invention is characterized by comprising a polarizer and the optical film. Thus, a polarizing plate having low haze can be produced.

In the present invention, the polarizer is preferably bonded to a surface of the optical film having a low surface roughness Ra on both surfaces thereof. This ensures the transportability of the optical film during the production of the polarizing plate, and makes it possible to obtain the polarizing plate with a high yield.

The image display device of the present invention is characterized by comprising the optical film. This can improve visibility.

The present invention and its constituent elements, and forms and modes for carrying out the present invention will be described in detail below. In the present application, "to" is used to include numerical values described before and after the "to" as the lower limit value and the upper limit value.

[ 1 ] outline of optical film

The optical film of the present invention is an optical film containing a cycloolefin resin, fine particles, and a surface conditioner, wherein the surface conditioner contains at least one of a silicone material, a fluorine material, a vinyl material, and an acrylic material, and the surface roughness Ra of the surface having a high surface roughness Ra is in the range of 3.0 to 50.0nm on both surfaces of the film. The optical film of the present invention may further contain various additives described later and a solvent used in film formation as a residual solvent.

1-1. cycloolefin resin

The cycloolefin resin contained in the optical film of the present invention is preferably a polymer of a cycloolefin monomer or a copolymer of a cycloolefin monomer and a copolymerizable monomer other than the cycloolefin monomer.

The cycloolefin monomer is preferably a cycloolefin monomer having a norbornene skeleton, and more preferably a cycloolefin monomer having a structure represented by the following general formula (A-1) or (A-2).

General formula (A-1)

In the general formula (A-1), R¹～R⁴Each independently represents a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group. p represents an integer of 0 to 2. Wherein all R are¹～R⁴Not simultaneously representing a hydrogen atom, R¹And R²Not simultaneously representing a hydrogen atom, R³And R⁴Not simultaneously representing a hydrogen atom.

As represented by R in the general formula (A-1)¹～R⁴The hydrocarbon group having 1 to 30 carbon atoms is preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms. The hydrocarbon group having 1 to 30 carbon atoms may further have a linking group containing a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom, for example. Examples of such linking groups include carbonyl, imino, ether, silyl ether linkagesAnd a 2-valent polar group such as a thioether bond. Examples of the hydrocarbon group having 1 to 30 carbon atoms include methyl, ethyl, propyl, butyl and the like.

In the general formula (A-1), R¹～R⁴Examples of the polar group represented include a carboxyl group, a hydroxyl group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amido group, and a cyano group. Among them, a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, and an aryloxycarbonyl group are preferable, and from the viewpoint of ensuring solubility in solution film formation, an alkoxycarbonyl group and an aryloxycarbonyl group are preferable.

From the viewpoint of improving the heat resistance of the optical film, p in the general formula (a-1) preferably represents 1 or 2. This is because when p represents 1 or 2, the volume of the obtained polymer increases and the glass transition temperature tends to increase.

General formula (A-2)

In the general formula (A-2), R⁵Represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having an alkyl group having 1 to 5 carbon atoms. R⁶Represents a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amido group, a cyano group, or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom). p represents an integer of 0 to 2.

R in the formula (A-1)⁵Preferably a hydrocarbon group having 1 to 5 carbon atoms, more preferably a hydrocarbon group having 1 to 3 carbon atoms.

R in the formula (A-2)⁶The compound preferably represents a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, and an aryloxycarbonyl group, and more preferably an alkoxycarbonyl group and an aryloxycarbonyl group from the viewpoint of ensuring solubility in solution film formation.

From the viewpoint of improving the heat resistance of the optical film, p in the general formula (a-2) preferably represents 1 or 2. This is because when p is 1 or 2, the volume of the obtained polymer increases and the glass transition temperature tends to increase.

The cyclic olefin monomer having a structure represented by the general formula (A-2) is improved in organic compoundsThe solubility in a solvent is preferable. In general, an organic compound has improved solubility in an organic solvent because crystallinity is reduced by breaking symmetry. R in the formula (A-2)⁵And R⁶Since only the ring-structured carbon atom on one side is substituted with respect to the symmetry axis of the molecule, the molecular symmetry is low, and thus the cycloolefin monomer having the structure represented by the general formula (a-2) has high solubility, and is suitable for the case of manufacturing an optical film by a solution casting method.

The content ratio of the cycloolefin monomer having the structure represented by the general formula (a-2) in the polymer of the cycloolefin monomer may be, for example, 70 mol% or more, preferably 80 mol% or more, and more preferably 100 mol% with respect to the total amount of all the cycloolefin monomers constituting the cycloolefin resin. When the cycloolefin monomer having a structure represented by the general formula (a-2) is contained in a certain amount or more, the orientation of the resin is improved, and thus the retardation value is easily increased.

Specific examples of the cycloolefin monomer having a structure represented by the general formula (A-1) are shown below as exemplified compounds 1 to 14, and specific examples of the cycloolefin monomer having a structure represented by the general formula (A-2) are shown below as exemplified compounds 15 to 34.

Examples of the copolymerizable monomer copolymerizable with the cycloolefin monomer include a copolymerizable monomer ring-opening copolymerizable with the cycloolefin monomer, a copolymerizable monomer addition copolymerizable with the cycloolefin monomer, and the like.

Examples of the ring-opening copolymerizable comonomer include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene and dicyclopentadiene.

Examples of the copolymerizable monomer to be addition-copolymerizable include unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, and (meth) acrylic esters. Examples of the unsaturated double bond-containing compound include olefin compounds having 2 to 12 (preferably 2 to 8) carbon atoms, and examples thereof include ethylene, propylene, butene and the like. Examples of the vinyl cyclic hydrocarbon monomer include vinyl cyclopentene monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. Examples of the (meth) acrylic acid ester include alkyl (meth) acrylates having 1 to 20 carbon atoms such as methyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth) acrylate.

The content of the cycloolefin monomer in the copolymer of the cycloolefin monomer and the copolymerizable monomer may be, for example, 20 to 80 mol%, and preferably 30 to 70 mol%, based on the total amount of all monomers constituting the copolymer.

As described above, the cycloolefin resin is a cycloolefin monomer having a norbornene skeleton, and is preferably a polymer obtained by polymerizing or copolymerizing a cycloolefin monomer having a structure represented by the general formula (A-1) or (A-2), and examples thereof include the following compounds.

(1) Ring-opened polymer of cycloolefin monomer

(2) Ring-opened copolymer of cycloolefin monomer and copolymerizable monomer ring-opening copolymerizable therewith

(3) Hydrogenated product of Ring-opened (co) polymer of the above (1) or (2)

(4) (Co) Polymer obtained by cyclizing the ring-opened (co) polymer of the above-mentioned (1) or (2) by Friedel-crafts reaction and then hydrogenating

(5) Saturated copolymer of cycloolefin monomer and unsaturated double bond-containing compound

(6) Addition copolymer of vinyl cyclic hydrocarbon monomer with cycloolefin monomer and hydrogenated product thereof

(7) Alternating copolymers of cycloolefin monomers and (meth) acrylates

The polymers (1) to (7) can be obtained by any known method, for example, the methods described in Japanese patent application laid-open Nos. 2008-107534 and 2005-227606. For example, the catalyst and solvent used in the ring-opening copolymerization of the above (2) can be the catalysts and solvents described in paragraphs 0019 to 0024 of Japanese patent application laid-open No. 2008-107534. The catalysts used for the hydrogenation in (3) and (6) can be, for example, the catalysts described in paragraphs 0025 to 0028 of Japanese patent application laid-open No. 2008-107534. The acidic compound used in the Friedel-crafts reaction of the above (4) can be, for example, an acidic compound described in paragraph 0029 of Japanese patent application laid-open No. 2008-107534. The catalysts used in the addition polymerizations of the above (5) to (7) can be, for example, the catalysts described in paragraphs 0058 to 0063 of Japanese patent laid-open No. 2005-227606. The alternating copolymerization reaction (7) can be carried out, for example, by the method described in paragraphs 0071 and 0072 of Japanese patent laid-open publication No. 2005-227606.

Among them, the polymers (1) to (3) and (5) are preferable, and the polymers (3) and (5) are more preferable. That is, the cycloolefin resin preferably contains at least one of the structural unit represented by the following general formula (B-1) and the structural unit represented by the following general formula (B-2), more preferably contains only the structural unit represented by the general formula (B-2), or contains both the structural unit represented by the general formula (B-1) and the structural unit represented by the general formula (B-2), from the viewpoint of improving the glass transition temperature and improving the light transmittance of the cycloolefin resin obtained. The structural unit represented by the general formula (B-1) is a structural unit derived from the cycloolefin monomer represented by the above general formula (A-1), and the structural unit represented by the general formula (B-2) is a structural unit derived from the cycloolefin monomer represented by the above general formula (A-2).

General formula (B-1)

In the general formula (B-1), X represents-CH ═ CH-or-CH₂CH₂-。R¹～R⁴And p is independently from R of the formula (A-1)¹～R⁴And p are synonymous.

General formula (B-2)

In the general formula (B-2), X represents-CH ═ CH-or-CH 2CH 2-. R⁵、R⁶And p is independently from R of the formula (A-2)⁵、R⁶And p are synonymous.

The cycloolefin resin according to the present invention may be a commercially available product. Examples of commercially available products of cycloolefin resins include Arton G (e.g., G7810, etc.), Arton F, Arton R (e.g., R4500, R4900, R5000, etc.), and Arton RX, which are manufactured by JSR corporation.

The intrinsic viscosity [. eta. ] inh of the cycloolefin resin is preferably 0.2 to 5cm at 30 DEG³A concentration of 0.3 to 3cm³A concentration of 0.4 to 1.5cm³/g。

The number average molecular weight (Mn) of the cycloolefin resin is preferably 8000 to 100000, more preferably 10000 to 80000, and further preferably 12000 to 50000. The weight average molecular weight (Mw) of the cycloolefin resin is preferably 20000 to 300000, more preferably 30000 to 250000, and further preferably 40000 to 200000. The number average molecular weight and the weight average molecular weight of the cycloolefin resin can be measured in terms of polystyrene by Gel Permeation Chromatography (GPC).

When the intrinsic viscosity [ η ] inh, the number average molecular weight and the weight average molecular weight are within the above ranges, the cycloolefin resin is excellent in heat resistance, water resistance, chemical resistance, mechanical properties and molding processability as a film.

The glass transition temperature (Tg) of the cycloolefin resin is usually 110 ℃ or higher, preferably 110 to 350 ℃, more preferably 120 to 250 ℃, and further preferably 120 to 220 ℃. When the Tg is 110 ℃ or higher, deformation under high temperature conditions is easily suppressed. On the other hand, when Tg is 350 ℃ or less, molding processing becomes easy, and deterioration of the resin due to heat during molding processing is also easily suppressed.

The content of the cycloolefin resin is preferably 70% by mass or more, and more preferably 80% by mass or more, with respect to all components excluding the solvent in the material constituting the optical film.

1-2. fine particles

The fine particles according to the present invention have a number average particle diameter of 400nm or less as measured by a transmission electron microscope. In this case, the particle diameter of each particle is defined as a diameter when a projection plane in the transmission electron microscope is converted into a circle having the same area. In order to prevent unnecessary scattering, the particle size of the fine particles is preferably very small compared to the wavelength of visible light, specifically, 1 to 200nm is a preferable range, more preferably 1 to 100nm, and particularly preferably 5 to 60 nm. The shape of the particles is not limited to spherical, and may be irregular.

The fine particles according to the present invention may be inorganic fine particles or organic fine particles. In addition, inorganic fine particles having a surface modified with an organic compound may be used.

The inorganic fine particles are preferably, for example, a silicon-containing compound (silicon compound), alumina, zirconia, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, or the like, more preferably a silicon compound or alumina, and particularly preferably silica. These include particles having a spherical shape, a flat plate shape, a non-specific shape (predetermined shape), and the like.

Examples of the fine particles of silica include commercially available products such as AEROSIL R972, R972V, R972CF, R974, R812, 50, 200V, 300, R202, OX50, TT600, R711, RY300, R106, R816, RA200HS, and MOX170 (available from aesosil corporation, japan).

As the fine particles of alumina, commercially available products such as AEROSIL Alu C, Alu130 and Alu C805 (see above, manufactured by AEROSIL Co., Ltd.) can be used.

Examples of the organic fine particles include, but are not limited to, composite fine particles of polystyrene resin, silicone resin, polyethylene resin, epoxy resin, polycarbonate resin, melamine resin, and the like, and acrylic-styrene resin, melamine-silica, and the like.

These inorganic fine particles and organic fine particles may be used alone, or 2 or more kinds thereof may be used in combination. When organic fine particles are used, it is preferable to use organic fine particles having a small difference between the refractive index in monodispersion and the refractive index of the resin.

The content of the fine particles is preferably in the range of 0.01 to 5.0 mass%, more preferably 0.05 to 3.0 mass%, based on the total components excluding the solvent in the material constituting the optical film.

1-3 surface conditioner

The surface conditioner of the present invention is a surface conditioner containing at least one of a silicone material, a fluorine-based material, a vinyl-based material, and an acrylic-based material.

As the silicone material, for example, a silicone surfactant or the like is preferably used, as the fluorine material, for example, a fluorine surfactant, a fluorine-siloxane graft compound, a fluorine compound or the like is preferably used, as the vinyl material, for example, a vinyl copolymer, a vinyl-siloxane graft compound or the like is preferably used, and as the acrylic material, for example, an acrylic-silicone graft compound, an acrylic copolymer or the like is preferably used.

Here, the silicone material means an oligomer or polymer having a siloxane skeleton as a repeating unit. The siloxane repeating structure may be present as a main chain or as a grafted side chain.

The fluorine-based material means an oligomer or polymer containing a fluorine atom in at least 1 repeating unit. The fluorine-containing repeating structure may be provided as a main chain or a side chain to be grafted.

The vinyl material is an oligomer or polymer having a repeating unit containing at least 1 of a vinyl group, a vinylidene group, and a vinylene group. The vinyl-containing repeating structure may be provided as a main chain or as a grafted side chain.

The acrylic material refers to an oligomer or polymer having an acryl group in a repeating unit. The acryl-containing repeating structure may be provided as a main chain or a side chain to be grafted.

Examples of the silicone-based surfactant include polyether-modified silicone and acrylic-modified silicone, and examples thereof include GL series (e.g., GL-01, GL-02R, GL-03 and GL-04R) manufactured by Kyowa chemical Co., Ltd., and Silface series (e.g., Silface SAG002, Silface SAG005, Silface SAG008 and Silface SAG 503A) manufactured by Nissan chemical industries, Ltd., and the like.

Examples of the fluorine-based surfactant include Megafac RS series, Megafac F-444 and Megafac F-556 manufactured by DIC.

The fluorine-siloxane graft compound is a compound of a copolymer obtained by grafting at least a fluorine-based resin with a polysiloxane and/or an organopolysiloxane containing a siloxane and/or an organosiloxane simple substance. Further, examples of commercially available products include ZX-022H, ZX-007C, ZX-049 and ZX-047-D manufactured by Fuji chemical industries, Ltd.

Further, examples of the fluorine-containing compound include OPTOOL DSX and OPTOOL DAC manufactured by Daikin industries and Co.

Examples of the acrylic copolymer include BYK-350 and BYK-352 manufactured by BYK Japan.

As the surface conditioner of the present invention, the following commercially available products can be used in addition to the above surface conditioner. Examples thereof include Kao corporation: emulgen 102KG, Emulgen 104P, Emulgen 105, Emulgen 106, Emulgen 108, Emulgen 109P, Emulgen 120, Emulgen 123P, Emulgen 147, Emulgen 210P, Emulgen 220, Emulgen 306P, Emulgen 320P, Emulgen 404, Emulgen 408, Emulgen 409PV, Emulgen 420, Emulgen 430, Emulgen 705, Emulgen 707, Emulgen 709, Emulgen 1108, Emulgen 1118S-70, Emulgen 1135S-70, Emulgen 2020G-HA, Emulgen 2025G, Emulgen LS-106, Emulgen LS-110, Emulgen LS114, Nissan chemical industry Co., Ltd.: surfynol 104E, Surfynol 104H, Surfynol 104A, Surfynol 104BC, Surfynol 104DPM, Surfynol 104PA, Surfynol 104PG-50, Surfynol 104S, Surfynol 420, Surfynol 440, Surfynol 465, Surfynol 485, Surfynol SE, manufactured by shin-Etsu chemical Co., Ltd.: FA-600, KC-89S, KR-500, KR-516, X-40-9296, KR-513, X-22-161A, X-22-162C, X-22-163, X-22-163A, X-164, X-22-164A, X-173 BX, X-22-174ASX, X-22-176DX, X-22-343, X-22-2046, X-22-2445, X-22-3939A, X-22-4039, X-22-4015, X-22-4272, X-22-4741, X-22-4952, X-22-6266, KF-50-100cs, KF-96L-1cs, KF-22-1 cs, KF-101, KF-102, KF-105, KF-351, KF-352, KF-353, KF-354L, KF-355A, KF-393, KF-615A, KF-618, KF-857, KF-859, KF-860, KF-862, KF-877, KF-889, KF-945, KF-1001, KF-1002, KF-1005, KF-2012, KF-2201, X-22-2404, X-22-2426, X-22-3710, KF-6004, KF-6011, KF-6015, KF-6123, KF-8001, KF-8010, KF-8012, X-22-9002, and the like.

The content of the surface conditioner is preferably in the range of 0.01 to 5.0 mass%, more preferably in the range of 0.05 to 3.0 mass%, based on the total components excluding the solvent in the material constituting the optical film. The effect of the present invention can be sufficiently exhibited by the content of the surface conditioner being 0.01 mass% or more, and the slidability can be more reliably imparted by the content of the surface conditioner being 5.0 mass% or less while suppressing the haze of the film to be low.

1-4. other additives

As described above, the optical film of the present invention may further contain other additives. Examples of such additives include ultraviolet absorbers and antioxidants.

(ultraviolet absorber)

The optical film of the present invention may also contain an ultraviolet absorber as an additive.

The ultraviolet absorber absorbs ultraviolet rays of 400nm or less, and thus can improve the durability of the optical film. The transmittance of the ultraviolet absorber at a wavelength of 370nm is preferably 10% or less, more preferably 5% or less, and still more preferably 2% or less.

Specific examples of the ultraviolet absorber are not particularly limited, and examples thereof include oxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex salt compounds, inorganic powders, and the like, and benzotriazole compounds and benzophenone compounds are particularly preferable.

More specifically, examples of the ultraviolet absorber include 5-chloro-2- (3, 5-di-sec-butyl-2-hydroxyphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, and 2, 4-benzyloxybenzophenone. Commercially available products can be used, and for example, Tinuvin 109 (a mixture of octyl-3- [ 3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl ] propenyl ester and 2-ethylhexyl-3- [ 3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl ] propenyl ester manufactured by BASF Japan, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 928(2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3, 3-tetramethylbutyl) phenol), and the like.

Further, a disk-shaped compound such as a compound having a 1,3, 5-triazine ring is also preferably used as the ultraviolet absorber. Further, as the ultraviolet absorber, a high molecular ultraviolet absorber can be preferably used, and a polymer type ultraviolet absorber is particularly preferably used.

As the triazine-based ultraviolet absorber, commercially available Tinuvin 400 (a reaction product of 2- (4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazin-2-yl) -5-hydroxyphenyl and ethylene oxide, manufactured by BASF JAPAN), Tinuvin 460(2, 4-bis [ 2-hydroxy-4-butoxyphenyl ] -6- (2, 4-dibutoxyphenyl) -1, 3-5-triazine), tinuvin 405 (a reaction product of 2- (2, 4-dihydroxyphenyl) -4, 6-bis- (2, 4-dimethylphenyl) -1,3, 5-triazine and (2-ethylhexyl) -glycidic acid ester), and the like.

As a method of adding the ultraviolet absorber, the ultraviolet absorber may be dissolved in an alcohol such as methanol, ethanol, or butanol, an organic solvent such as dichloromethane, methyl acetate, acetone, or dioxolane, or a mixed solvent thereof, and then added to a resin solution (coating material) used for producing an optical film, or directly added to the coating material. Substances insoluble in organic solvents such as inorganic powders are dispersed in organic solvents and cellulose acetate using a dissolver or a sand mixer, and then added to the coating material.

The content of the ultraviolet absorber is, for example, preferably in the range of 0.5 to 10% by mass, and more preferably in the range of 0.6 to 4% by mass, relative to the optical film.

(antioxidant)

The optical film of the present invention may also contain an antioxidant (deterioration preventing agent) as another additive.

As the antioxidant, a hindered phenol-based compound is preferably used, and examples thereof include 2, 6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propenyl ], 1, 6-hexanediol-bis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propenyl ], 2, 4-bis- (n-octylthio) -6- (4-hydroxy-3, 5-di-t-butylanilino) -1,3, 5-triazine, 2-thiodiethylene bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propenyl ], octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propenyl, N' -hexamethylenebis (3, 5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene, tris (3, 5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate, and the like.

The content of the antioxidant is, for example, preferably in the range of 1 to 10000 ppm by mass, and more preferably in the range of 10 to 1000 ppm by mass, relative to the optical film.

1-5 Properties of optical film

(surface roughness Ra)

The surface roughness Ra of the surface with high surface roughness Ra of the two surfaces of the optical film is within the range of 3.0-50.0 nm, and preferably within the range of 4.0-40.0 nm. When the surface roughness Ra is 3.0nm or more, the sliding property of the optical film is improved, and unevenness and wrinkling of the surface during conveyance can be suppressed. When the surface roughness Ra is 50nm or less, scattering of light due to unevenness on the surface of the optical film can be suppressed, and the haze value can be made low. In the present invention, the surface roughness Ra is JIS B0601: 2001, the arithmetic average roughness (Ra) as defined in.

The surface roughness Ra of the surface with low surface roughness Ra of the two surfaces of the optical film of the invention is preferably within the range of 2.0-30.0 nm, and more preferably within the range of 2.0-20.0 nm. When the surface roughness Ra is within this range, when the polarizer is bonded to the surface of the optical film having a low surface roughness Ra to produce a polarizing plate, the surface having a high surface roughness Ra has less unevenness, and therefore, a gap is less likely to be formed at the bonding interface with the polarizer, and scattering of light can be suppressed.

Here, as described above, by containing the fine particles and the surface conditioner together in the film containing the cycloolefin resin, the fine particles and the surface conditioner can be present in a large amount on one surface of the film (surface on the air interface side at the time of film formation), and the fine particles and the surface conditioner are also partially present on the other surface of the film (surface on the support (for example, a metal support described later) side at the time of film formation).

This is considered to be because the solvent is a good solvent in the drying step of the film-like material in the production of the optical film and therefore preferentially volatilizes, but since there are some good solvent components that do not volatilize until the final stage of drying, the above-mentioned associated body solvated in the good solvent is also present on the other surface of the film. Therefore, the presence amount of the fine particles and the surface conditioner is small as compared with one surface of the film, but the fine particles and the surface conditioner form an associated body, and therefore, the surface roughness Ra having a large particle diameter and in the above-described range can be obtained.

As a method for controlling the surface roughness Ra of the other surface within the above range, there is a method of appropriately adjusting the content of fine particles and surface conditioner, and stretching conditions at the time of film production.

Further, the difference in surface roughness Ra between both surfaces of the optical film is preferably 1.0nm or more. By making the surface roughness Ra of both surfaces of the film different, the transportability of the optical film can be improved while keeping the haze value low.

The surface roughness Ra can be measured by an optical interference type surface roughness measuring instrument, for example, an optical interference type surface roughness measuring instrument RST/PLUS (product of WYKO corporation).

(optical Properties)

The total light transmittance of the optical film is preferably 90% or more, more preferably 92% or more. The practical upper limit is about 99%. The haze value is preferably 10% or less, more preferably 2% or less. The total light transmittance and haze value can be measured according to JIS K7361 and JIS K7136, respectively.

(retardation value)

The use of the optical film of the present invention is not particularly limited, and the optical film may be used as a polarizer protective film or a retardation film. When used as a retardation film, various retardation values can be obtained depending on the use thereof.

For example, when the optical film of the present invention is used as a retardation film for VA liquid crystal, the retardation value Ro in the in-plane direction measured in an environment of a measurement wavelength of 590nm and 23 ℃ 55% RH satisfies preferably 10 nm. ltoreq. Ro.ltoreq.100 nm, more preferably 20 nm. ltoreq. Ro.ltoreq.80 nm. The retardation value Rt in the thickness direction preferably satisfies 70 nm. ltoreq. Rt.ltoreq.200 nm, more preferably 90 nm. ltoreq. Rt.ltoreq.150 nm.

The retardation values Ro and Rt are values defined by the following formulas (i) and (ii).

Formula (i): ro ═ n_x-n_y)×d

Formula (ii): rt { (n)_x+n_y)/2-n_z}×d

(in the formulae (i) and (ii), n_xRefractive index n in the slow axis direction in the optical film plane_yDenotes a refractive index in a direction perpendicular to the slow axis in the plane of the optical film, n_zThe refractive index in the thickness direction of the optical film is shown, and d represents the thickness (nm) of the optical film. )

When the optical film of the present invention is used as a lambda/4 film, the retardation value Ro in the in-plane direction measured in an environment at a measurement wavelength of 590nm and 23 DEG.55% RH preferably satisfies 50nm Ro 250nm, more preferably 70nm Ro 200 nm. The retardation value Rt in the thickness direction preferably satisfies-200 nm. ltoreq. Rt.ltoreq.200 nm, more preferably-120 nm. ltoreq. Rt.ltoreq.120 nm.

Further, when the optical film of the present invention is used as a zero retardation film, the retardation value Ro in the in-plane direction measured in an environment of a measurement wavelength of 590nm and 23 ℃. 55% RH preferably satisfies 0 nm. ltoreq. Ro.ltoreq.5 nm, and the retardation value Rt in the thickness direction preferably satisfies-5 nm. ltoreq. Rt.ltoreq.5 nm.

The retardation value can be determined at a wavelength of 590nm at 23 ℃ 55% RH using, for example, an auto birefringence meter Axo Scan (Axo Scan Mueller Matrix Polarimeter, manufactured by Acrometrix). The use of the optical film controlled to have the retardation value is preferable in that the optical film is excellent in visibility when used in an image display device such as a touch panel or a liquid crystal display device. The retardation value can be adjusted by the kind or addition amount of the fine particles, the surface conditioner, and other additives, the thickness of the optical film, or the stretching condition, and the like.

(thickness)

From the viewpoint of making the retardation values Ro and Rt within the above ranges and making the optical film thinner, the thickness of the optical film is, for example, preferably 3 to 200 μm, more preferably 5 to 100 μm, and still more preferably 7 to 40 μm. In particular, the optical film of the present invention provides slidability, and therefore can relax the transport tension and provide excellent transportability even when the film is made thin.

2. Method for manufacturing optical film

The optical film of the present invention is produced by a solution casting method using two or more solvents. That is, the method for producing an optical film of the present invention preferably includes the steps of: a step (coating material preparation step) of dissolving at least a cycloolefin resin, fine particles, and a surface conditioner in two or more solvents to obtain a coating material (resin solution); a step (casting/peeling step) of obtaining a film-like material by peeling the coating material from the support; and a step (drying step) of drying the film-like material. The method for producing an optical film of the present invention preferably includes a step of stretching the film-like material (stretching step) between the casting/peeling step and the drying step, and preferably includes a step of winding the obtained optical film after the drying step (winding step).

2-1. preparation of coating

The coating material preparation process will be explained. The concentration of the resin in the dope is preferably high so that the drying load after casting on the metal support can be reduced, but if the concentration of the resin is too high, the load at the time of filtration increases and the filtration accuracy deteriorates. The concentration having both of these effects is preferably 10 to 45 mass%, and more preferably 15 to 40 mass%.

The solvent contained in the coating material may be used in combination of 2 or more, and it is preferable to use a mixture of a good solvent and a poor solvent for the resin from the viewpoint of production efficiency, and it is preferable to use a large amount of a good solvent from the viewpoint of solubility of the resin. The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98 mass% for the good solvent and 2 to 30 mass% for the poor solvent. Here, as the good solvent and the poor solvent, a solvent which dissolves the resin used alone is defined as a good solvent, and a solvent which swells or does not dissolve when used alone is defined as a poor solvent.

In addition, the combination of the organic solvents useful for the preparation of the coating material is not particularly limited as long as the cycloolefin resin and other additives can be dissolved at the same time. For example, the chlorine-based organic solvent includes dichloromethane and chloroform, and the non-chlorine-based organic solvent includes methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1, 3-dioxolane, 1, 4-dioxolane

The organic solvent used in the present invention is not particularly limited, and examples thereof include, but not limited to, hexane, cyclohexane, cyclohexanone, toluene, p-xylene, ethyl formate, 2,2, 2-trifluoroethanol, 2,2,3, 3-hexafluoro-1-propanol, 1, 3-difluoro-2-propanol, 1,1,1,3,3, 3-hexafluoro-2-methyl-2-propanol, 1,1,3,3, 3-hexafluoro-2-propanol, 2,2,3,3, 3-pentafluoro-1-propanol, nitroethane, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and tert-butanol.

The coating material is preferably a coating material in which a cycloolefin resin, fine particles, a surface conditioner, and other additives are dissolved in the solvent in a total amount of 15 to 45 mass%.

As a method for dissolving the resin in the solvent in the preparation of the above-mentioned coating material, a general method can be used. In particular, from the viewpoint of reducing the burden on the dissolving apparatus and preventing the coloring of the resin, the resin is preferably dissolved at normal temperature and normal pressure.

Next, the solution in which the resin is dissolved is filtered using an appropriate filter medium such as filter paper. As the filter material, it is preferable that the absolute filtration accuracy is low in order to remove the insoluble matter and the like, but if the absolute filtration accuracy is too low, there is a problem that clogging of the filter material is likely to occur. Therefore, the filter medium has an absolute filtration accuracy of preferably 0.008mm or less, more preferably 0.001 to 0.008mm, and still more preferably 0.003 to 0.006 mm.

The material of the filter medium is not particularly limited, and a common filter medium can be used, and a filter medium made of plastic such as polypropylene or teflon (registered trademark), or a filter medium made of metal such as stainless steel is preferable because fibers are not detached. It is preferable to remove and reduce impurities contained in the resin as a raw material, particularly, bright foreign matters by filtration.

The bright spot foreign matter is a spot (foreign matter) which is observed by irradiating light from one side of one polarizing plate with 2 polarizing plates arranged in a crossed nicols state and disposing an optical film or the like therebetween and by leaking light from the opposite side when viewed from the other side, and the number of bright spots having a diameter of 0.01mm or more is preferably 200 spots/cm²The following. More preferably 100/cm²The number of molecules is preferably 50/m²The number of the carbon atoms is particularly preferably 0 to 10/cm²Within the range of (1). Preferably, the number of bright spots of 0.01mm or less is also small.

The filtration of the dope can be carried out by a usual method, and it is preferable that the difference in filtration pressure (referred to as differential pressure) between before and after the filtration is small in a method of heating the dope at a temperature of not less than the boiling point of the solvent under normal pressure and in a range where the solvent does not boil under pressure. The preferable temperature is 45-120 ℃, more preferably 45-70 ℃, and further preferably 45-55 ℃.

The filtration pressure is preferably low. Specifically, the filtration pressure is preferably 1.6MPa or less, more preferably 1.2MPa or less, and still more preferably 1.0MPa or less.

2-2. pouring and stripping procedure

The obtained dope was discharged from a casting die to be cast on a metal support, and the obtained cast film was dried and peeled to obtain a film-like material. The casting width can be set to 1 to 4m, for example. As the metal support, a drum having a surface coated with a stainless steel belt or a casting finish may be used. The surface of the metal support is preferably mirror finished. The support body to which the coating material is poured is not limited to a metal, and may be made of any material such as resin.

The surface temperature of the metal support is preferably from-50 ℃ to a temperature lower than the boiling point of the solvent, and since a high temperature can increase the drying rate of the film-like material, if it is too high, the film-like material foams or the planarity is deteriorated. Therefore, the surface temperature of the metal support is preferably 0 to 40 ℃, and more preferably 5 to 30 ℃.

The method of controlling the temperature of the metal support is not particularly limited, and examples thereof include a method of blowing warm air or cold air, and a method of bringing warm water into contact with the back surface of the metal support. Since heat transfer can be efficiently performed by using warm water, the time for the temperature of the metal support to reach a constant temperature is short, which is preferable.

When warm air is used, warm air having a temperature higher than the boiling point of the solvent may be used in consideration of the temperature drop of the web (ウェブ) due to the latent heat of evaporation of the solvent, and air having a temperature higher than the target temperature may be used while preventing foaming.

In order to obtain a film-like material having good planarity, the amount of the solvent remaining in the film-like material when peeled from the metal support is preferably 10 to 150 mass%, more preferably 20 to 40 mass% or 60 to 130 mass%, and still more preferably 20 to 30 mass% or 70 to 120 mass%.

Here, the residual solvent amount of the film-like material is defined by the following formula.

Residual solvent amount (% by mass) { (M-N)/N } × 100

(in the above formula, M represents the mass of the film, and N represents the mass of the film after heating at 120 ℃ for 1 hour.)

2-3. drying procedure

The drying step preferably dries the film-like material peeled from the metal support until the amount of the residual solvent is 1 mass% or less, more preferably 0.1 mass% or less, and particularly preferably in the range of 0 to 0.01 mass%. Thus, an optical film can be obtained.

In the film drying step, a roll drying method (a method of drying a film by passing the film alternately through a plurality of rolls arranged vertically) is generally used, and the film is dried while being conveyed by a tenter method.

In particular, it is preferable to change the temperature of the metal support and the temperature of the drying air during the period from pouring to peeling to efficiently dry the metal support.

In the present invention, it is considered that the fine particles and the surface conditioner form an associated body in the coating material or the film-like material, and the associated body has a high affinity for the good solvent, so that the associated body moves to the surface of the film on the air interface side together with the good solvent volatilized from the film-like material in the drying step, and an optical film in which the fine particles and the surface conditioner are deviated on one surface side can be obtained.

Thus, by producing an optical film by a solution casting method using two or more solvents, the optical film can be provided with slidability to improve transportability, and a polarizing plate or the like can be produced in high yield without using a protective film.

2-4 stretching process

In the stretching step, the film obtained by peeling is stretched to adjust the phase difference.

The stretching may be performed in at least one direction. The stretching direction may be any of a longitudinal direction (MD direction) of the film, a width direction (TD direction) perpendicular to the longitudinal direction of the film, and a direction inclined with respect to the longitudinal direction of the film. The stretching may be sequential stretching or simultaneous stretching.

The stretching ratios in the biaxial directions perpendicular to each other are preferably in the range of 1.0 to 2.0 times in the MD direction and 1.05 to 2.0 times in the TD direction, more preferably in the range of 1.0 to 1.5 times in the MD direction and 1.05 to 2.0 times in the TD direction, respectively. For example, a method in which a circumferential speed difference is applied to a plurality of rolls, and stretching is performed in the MD by the roll circumferential speed difference therebetween; a method of fixing both ends of the film-like material with clips or needle plates, expanding the intervals of the clips or needle plates in the advancing direction and stretching in the MD direction; a method of stretching in the TD direction while expanding in the transverse direction as well; or a method of stretching in both directions by stretching in the MD direction and the TD direction.

These widthwise holding and widthwise stretching in the stretching step are preferably performed by a tenter, and may be a pin tenter or a clip tenter.

The film transport tension of a tenter or the like is also dependent on the temperature, and is preferably in the range of 120 to 200N/m, more preferably in the range of 140 to 200N/m, and most preferably in the range of 140 to 160N/m.

When the glass transition temperature of the optical film is Tg, the temperature at the time of stretching is preferably within the range of (Tg-30) to (Tg +100) ° C, more preferably within the range of (Tg-20) to (Tg +80) ° C, and still more preferably within the range of (Tg-5) to (Tg +20) ° C.

The Tg of the optical film can be controlled according to the kind of material constituting the optical film and the ratio of the material constituting the optical film. The Tg of the optical film at the time of drying is preferably 110 ℃ or higher, more preferably 120 ℃ or higher, and particularly preferably 150 ℃ or higher. The Tg of the optical film is preferably 190 ℃ or lower, more preferably 170 ℃ or lower. The Tg of the optical film can be determined by the method described in JIS K7121.

It is preferable that the temperature of the optical film during stretching is Tg +10 ℃ or higher and the stretching magnification is 1.10 times or more, because appropriate roughness can be imparted to the surface of the optical film. It is preferable to impart an appropriate roughness to the surface of the optical film because the slidability is improved and the surface processability is improved.

2-5 coiling procedure

In the winding step, the obtained optical film is wound by a winder. The winding method may be a commonly used method, and for example, a constant torque method, a constant tension method, a taper tension method, a programmed tension control method in which an internal stress is constant, or the like may be used.

The optical film of the present invention is preferably long, and more specifically, preferably has a length of about 100 to 7000 m. Such a long optical film can be generally provided in the form of a roll wound around a direction perpendicular to the longitudinal direction as a winding axis. The width of the optical film is preferably 1.3 to 4m, and more preferably 1.4 to 2 m. When the length and width of the optical film are within the above ranges, the optical film itself is excellent in handling properties and processing characteristics in the application of the functional layer and the like.

Before winding, the end of the optical film is cut to the width of the product, and embossing (embossing) may be performed on both ends in order to prevent sticking and scratching during winding. As a method of embossing, there is a method of processing an optical film by heating and pressing the optical film using a metal ring having an uneven pattern on a side surface. The clip holding portions at both ends of the optical film are usually deformed and cannot be used as a product, and therefore, the clip holding portions are cut off, and the cut-off pieces are reused as a raw material.

< 3. polarizing plate >

The polarizing plate of the present invention is characterized by comprising a polarizer and the optical film.

The polarizing plate of the present invention can be produced by a general method. For example, it is preferable that the optical film of the present invention is corona-treated, and the treated optical film is attached to at least one surface of a polarizer produced by immersing and stretching in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. The polarizer is preferably bonded to the surface having a low surface roughness Ra of both surfaces of the optical film of the present invention.

The optical Film, commercially available KC8UX, KC4UX, KC4UY, KC8UY, KC6UA, KC4UA, KC4UE, KC4CZ, KC8UCR, KC4FR (Konica Minolta Co., Ltd.), Arton Film (JSR Corp.), Zeonor Film (Nippon Zeon Co., Ltd.), and the like may be attached to the other surface of the polarizer.

The polarizer is a device that transmits only light having a polarization plane in a certain direction, and a typical polarizer known at present is a polyvinyl alcohol-based polarizing film. The polyvinyl alcohol-based polarizing film includes a polarizing film obtained by dyeing iodine on a polyvinyl alcohol-based film, and a polarizing film obtained by dyeing a dichroic dye.

The polyvinyl alcohol-based polarizing film may be a film obtained by uniaxially stretching a polyvinyl alcohol-based film and then dyeing the film with iodine or a dichroic dye (preferably a film subjected to a durability treatment with a boron compound), or a film obtained by uniaxially stretching a polyvinyl alcohol-based film after dyeing the film with iodine or a dichroic dye (preferably a film subjected to a durability treatment with a boron compound). The absorption axis of the polarizer is generally parallel to the direction of maximum stretching.

As the polarizer, for example, an ethylene-modified polyvinyl alcohol having an ethylene unit content of 1 to 4 mol%, a polymerization degree of 2000 to 4000, and a saponification degree of 99.0 to 99.99 mol% as described in Japanese patent application laid-open No. 2003-248123 or Japanese patent application laid-open No. 2003-342322 can be used. Among them, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ℃ is preferably used.

The thickness of the polarizer is preferably within a range of 5 to 30 μm, and more preferably within a range of 5 to 20 μm from the viewpoint of thinning of the polarizing plate.

[ 4 ] image display device

The image display device of the present invention is characterized by comprising the optical film. This is preferable in that excellent visibility and unevenness of performance can be exhibited. Examples of the image display device include a reflective type, transmissive type, and transflective type liquid crystal display device, a liquid crystal display device of various driving methods such as TN type, STN type, OCB type, VA type, IPS type, and ECB type, a touch panel display device, an organic EL display device, and a plasma display device.

The optical film of the present invention may be used, for example, as an inner touch panel (インナータッチパネル) using a touch panel member below an upper surface side polarizing plate of a liquid crystal display device (composed of an upper surface side polarizing plate, a liquid crystal cell, and a lower surface side polarizing plate), or as a capacitive touch panel.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In the examples, "part" or "%" is used, and unless otherwise specified, "part by mass" or "% by mass" is used.

First, various materials used in the present embodiment will be described.

(1) Cycloolefin resin

Arton G7810: ARTON-G7810 (manufactured by JSR corporation), cycloolefin resin (copolymer of monomer represented by formula (a-2) and other monomer (polymer of the above-mentioned (5)), weight average molecular weight Mw 140000)

Arton R5000: ARTON-R5000 (manufactured by JSR corporation), cycloolefin resin (copolymer of monomer represented by formula (A-1) and monomer represented by formula (A-2) and other monomer (polymer of the above-mentioned (5)), weight average molecular weight Mw 50000)

Arton RX 4500: ARTON-RX4500 (manufactured by JSR corporation), cycloolefin resin (copolymer of monomer represented by formula (A-1) and monomer represented by formula (A-2) and other monomer (polymer of the above-mentioned (5)), weight average molecular weight Mw 63000)

Arton RH 4900: ARTON-RH4900 (manufactured by JSR corporation), cycloolefin resin (copolymer of monomer represented by formula (A-1) and monomer represented by formula (A-2) and other monomer (polymer of the above-mentioned (5)), weight average molecular weight Mw 57000)

(2) Microparticles

(2-1) silicon Compound-containing microparticles

R812: silica fine particles surface-modified with trimethylsilyl group (manufactured by AEROSIL Co., Ltd., Japan) and having an average primary particle diameter of 7nm

R816: silica fine particles surface-modified with acrylic group (manufactured by AEROSIL Co., Ltd., Japan) and having an average primary particle diameter of 12nm

R106: silica fine particles having a surface modified with octamethylcyclotetrasilyl group (manufactured by AEROSIL Co., Ltd., Japan) and having an average primary particle diameter of 7nm

R972V: silica fine particles surface-modified with dimethylsilyl group (manufactured by AEROSIL Co., Ltd., Japan) and having an average primary particle diameter of 12nm

200V: silica Fine particles (manufactured by AEROSIL Co., Ltd., Japan) having an average primary particle diameter of 12nm

300V: silica Fine particles (manufactured by AEROSIL Co., Ltd., Japan) having an average primary particle diameter of 7nm

RY 300: silica fine particles surface-modified with Dimethicone ion (manufactured by AEROSIL Co., Ltd., Japan) having an average primary particle diameter of 12nm

RA200 HS: silica fine particles having a surface modified with trimethylsilyl group and amino group (manufactured by AEROSIL Co., Ltd., Japan) and having an average primary particle diameter of 12nm

R711: silica fine particles surface-modified with methacryloxysilane (manufactured by AEROSIL Co., Ltd., Japan) and having an average primary particle diameter of 12nm

MOX 170: silica/alumina fine particles (manufactured by AEROSIL Co., Ltd., Japan) having an average primary particle diameter of 13nm

(2-2) other microparticles

Alu 130: alumina fine particles (manufactured by AEROSIL Co., Ltd., Japan) having an average primary particle diameter of 20nm

TiO₂P90: titanium dioxide Fine particles (manufactured by AEROSIL Co., Ltd., Japan) having an average primary particle diameter of 20nm

Kraton RP 6935: styrene-ethylene-butene-styrene Block copolymer (manufactured by Kraton Polymer Japan K.K.) having an average Primary particle diameter of 18nm

(3) Surface conditioner

(3-1) organosilicon Material

GL-01: acrylic-modified silicone (available from Kyoeisha chemical Co., Ltd.), weight-average molecular weight Mw 5200

GL-03: acrylic-modified silicone (available from Kyoeisha chemical Co., Ltd.), weight average molecular weight Mw 4100

GL-04R: acrylic-modified Silicone (available from Kyoeisha chemical Co., Ltd.), weight-average molecular weight Mw of 4700

SAG 005: polyether-modified silicone (Silface SAG005, manufactured by Nikken chemical industries Co., Ltd.) having a weight-average molecular weight Mw of 2800

SAG 008: polyether-modified silicone (Silface SAG008, manufactured by Nikken chemical industries Co., Ltd.) having a weight-average molecular weight Mw of 7900

(3-2) fluorine-based Material

Lebron: tetrafluoroethylene resin (Daikin corporation) having a weight average molecular weight Mw of 2000

(3-3) vinyl Material

P-410 EF: vinyl Polymer (manufactured by Nanzi chemical Co., Ltd.), weight average molecular weight Mw 4500

(3-4) acrylic acid-based Material

LF-1984: acrylic acid polymer (manufactured by Nanben chemical Co., Ltd.), weight average molecular weight Mw 3000

230: acrylic polymer (manufactured by Nanben chemical Co., Ltd.), weight average molecular weight Mw 3500

Production of optical film 101

(preparation of silica Dispersion dilution)

After 10 parts by mass of AERO SIL R812 and 80 parts by mass of ethanol were mixed by stirring with a dissolver for 30 minutes, the mixture was dispersed by a Manton Gaulin (homogenizer) to prepare a silica dispersion. 80 parts by mass of methylene chloride was added to the prepared silica dispersion with stirring, and after stirring and mixing for 30 minutes by a dissolver, the mixture was filtered through a fine particle dispersion dilution filter (AdvantechToyo Co., Ltd.: Polypropylene wire edge filter TCW-PPS-1N) to prepare a silica dispersion dilution.

(preparation of coating Material)

The above components were put into a closed vessel, heated and stirred to be completely dissolved, and filtered by using an Amin Filter paper No.24 manufactured by Amin Filter paper Co.

Subsequently, the film was uniformly cast on a stainless steel band support by using a band casting film-forming apparatus. The solvent was evaporated on the stainless steel tape support until the amount of the residual solvent was 80 mass%, and the film was peeled off from the stainless steel tape support. The resulting web was kept at 35 ℃ to further evaporate the solvent, cut into 1.15m width, and dried at a drying temperature of 160 ℃. Thereafter, the film was dried for 15 minutes while being conveyed in a drying apparatus at 130 ℃ by a plurality of rolls, cut into a width of 1.0m, subjected to knurling with a width of 10mm and a height of 5 μm at both ends of the film, and wound up into a roll core to obtain an optical film 101. The optical film 101 had a thickness of 20 μm and a roll length of 5000 m. Further, the stretching ratio in the MD direction calculated from the rotation speed of the stainless steel belt support and the running speed of the tenter was 1.01 times.

Production of optical films 102 to 109

Optical films 102 to 109 were produced in the same manner as in table 1 except that the surface conditioner was changed to the one described in table 1 in the production of the optical film 101.

Production of optical films 110 to 116

In the production of the optical film 102, the optical films 110 to 116 were produced in the same manner except that the amounts of the fine particles and the surface conditioner added were changed as described in table 1 so that the contents of the fine particles and the surface conditioner in the finally obtained film were changed.

Production of optical films 117 to 128

Optical films 117 to 128 were produced in the same manner as in the above-described optical film 102 except that the fine particles were changed as described in table 2.

Production of optical films 129 to 131

Optical films 129 to 131 were produced in the same manner as in the production of the optical film 102, except that the cycloolefin resin was changed as described in table 2.

Production of optical film 132 (comparative example)

In the above-described production of the optical film 102, the optical film 132 was produced in the same manner except that the amounts of the fine particles and the surface conditioner added were changed as described in table 2 so that the contents of the fine particles and the surface conditioner in the finally obtained film were changed.

Production of optical film 133 (comparative example)

An optical film 133 was produced in the same manner as in the production of the optical film 101, except that no surface conditioner was added during the preparation of the coating material.

Production of optical film 134 (comparative example)

The optical film 134 is similarly produced except that no fine particles or surface conditioner is added in the preparation of the coating material in the production of the optical film 101.

Production of optical film 135 (comparative example)

The optical Film 135 was formed by peeling and removing a protective Film from Zeonor Film ZF14 manufactured by Nippon Zeon corporation.

Measurement and evaluation of physical Properties of optical films 101 to 135

The following physical properties were measured and evaluated for the optical films 101 to 135 thus produced. The measurement results and evaluation results are shown in tables 1 and 2.

(measurement of surface roughness Ra)

The arithmetic surface roughness Ra of both surfaces of each optical film thus produced was measured by an optical interference surface roughness meter RST/PLUS (WYKO) in accordance with JIS B0601 at 23 ℃ and 55% RH.

In this case, of both surfaces of each optical film, the surface that was in contact with the air interface when the optical film was produced was referred to as the a-surface, and the surface that was in contact with the stainless steel belt support when the optical film was produced was referred to as the B-surface.

(evaluation of haze value)

Each of the optical films thus produced was cut into 3.0cm × 3.0cm to prepare test pieces. The test piece was measured for haze value by a haze meter NDH-2000 (manufactured by Nippon Denshoku industries Co., Ltd.) at 23 ℃ and 55% RH in accordance with JIS K7136, and evaluated based on the following criteria.

O: the haze value is less than 2.0.

And (delta): the haze value is 2.0 or more and less than 5.0.

X: the haze value is 5.0 or more.

[ TABLE 1 ]

[ TABLE 2 ]

Production 201 of image display device

(production of polarizer)

A polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched in the longitudinal direction of the film (temperature 110 ℃ C., stretching ratio 5 times). The resultant was immersed in an aqueous solution of 0.075g of iodine, 5g of potassium iodide and 100g of water for 60 seconds, and then immersed in an aqueous solution of 6g of potassium iodide, 7.5g of boric acid and 100g of water at 68 ℃. The resultant was washed with water and dried to obtain a polarizer having a thickness of 20 μm. The absorption axis of the polarizer is parallel to the long side direction.

(preparation of No. 1 polarizing plate (visible side polarizing plate))

Next, the optical film 102 produced above was bonded to one surface of the polarizer produced above and KC4UA (polarizer protective film) produced by Konica Minolta was bonded to the other surface thereof to produce a polarizing plate according to the following steps 1 to 4.

Step 1: the B-side of the optical film 102 thus produced was subjected to corona discharge to perform corona treatment. Further, KC4UA (polarizer protective film) manufactured by Konica Minolta was immersed in a2 mol/L sodium hydroxide solution at 60 ℃ for 90 seconds, and then washed with water and dried to saponify the surface of the polarizer attached thereto.

And a step 2: the polarizer was immersed in a polyvinyl alcohol adhesive tank containing 2 mass% of solid content for 1 to 2 seconds. Next, the excess adhesive attached to the polarizer was gently wiped off, and then disposed on the B-side of the optical film 102 subjected to the corona treatment in step 1.

Step 3: an optical film 102, a polarizer, and a polarizer protective film saponified in the step 1 are pressed at a pressure of 20 to 30N/cm²And the laminate was obtained by bonding at a conveying speed of about 2 m/min.

And step 4: the laminate obtained in step 3 was dried in a dryer at 80 ℃ for 2 minutes to obtain the 1 st polarizing plate having a laminated structure of KC4UA (polarizer protective film)/polarizer/optical film 102.

(preparation of No.2 polarizing plate (backlight side polarizing plate))

The 2 nd polarizing plate having a laminated structure of the optical film 102/polarizer/KC 4UA (polarizer protective film) was produced in the same manner as the production of the 1 st polarizing plate.

(production of image display device)

An IPS system Xperia Z2D 6502 (product of Sony corporation) was prepared as a portable liquid crystal display device. The 2 polarizing plates were peeled off from the apparatus, and the 1 st polarizing plate prepared above was attached to the visible side surface of the liquid crystal cell via an adhesive, and the 2 nd polarizing plate prepared above was attached to the backlight side surface to prepare the image display apparatus 1.

The 1 st polarizing plate was attached so that KC4UA was on the visible side. The polarizing plate 2 was attached so that KC4UA was on the backlight side.

Production of image display devices 202 to 216

Image display devices 202 to 216 were produced in the same manner as described above except that the optical film 102 was changed as shown in table 3 in the production of the liquid crystal display device 201.

Production of image display apparatus 217

An image display device 217 was produced in the same manner as in the production of the liquid crystal display device 201, except that an optical film 135 (indicated as "135 (PF)" in table 3) in a state before the protective film was peeled and removed was used in place of the optical film 102.

Evaluation of image display devices 201 to 217

The following evaluations were performed on the manufactured image display devices 201 to 217. The evaluation results are shown in table 3.

(evaluation of surface irregularity during transportation)

In the production of the 1 st polarizing plate, the optical film was visually observed during the transport immediately before the lamination with the polarizer, and the evaluation was performed according to the following criteria.

O: surface irregularities were not observed at all.

And (delta): surface irregularities were confirmed at the membrane end.

X: surface irregularities were observed on the entire film.

(evaluation of wrinkling during transportation)

O: no wrinkling was observed at all.

And (delta): wrinkling was confirmed at the film end.

X: wrinkling was confirmed in the film as a whole.

(evaluation of Defect transfer)

The defect transfer caused by the protective film was evaluated in the following manner.

That is, the 1 st polarizing plate prepared as described above was cut into 1m pieces²The test piece was prepared in size, and the number of punctate bright spots was visually measured with the test piece directed toward the light source, and evaluated according to the following criteria. The spot-like bright spots measured were regarded as defects transferred from the protective film.

O: the number of defects is less than 1/m²

X: number of defectsIs 1 piece/m²The above

(evaluation of light leakage)

The backlights of the image display devices 201 to 217 manufactured as described above were continuously lit for 1 week in an environment of 23 ℃ and 55% RH, and then the contrast (60 ° contrast) in the direction inclined by 60 ° from the normal direction of the display screen of the image display device was measured. Specifically, the luminance in the 60 ° direction when the image display device was white-displayed and the luminance in the 60 ° direction when the image display device was black-displayed were measured using EZ-Contrast160D manufactured by ELDIM corporation, respectively, and the ratio of these was obtained (60 ° Contrast: luminance in the 60 ° direction when white was displayed/luminance in the 60 ° direction when black was displayed). The contrast of 60 ° was evaluated based on the following criteria, with the contrast from the front being taken as 100.

O: the 60 ° contrast is 90 or more and less than 100.

And (delta): the 60 DEG contrast is 80 or more and less than 90.

X: the 60 ° contrast is less than 80.

[ TABLE 3 ]

In the image display devices 201 to 208, 212, and 213, the optical films used have surface roughness Ra of a surface and B surface in an appropriate range and have good slidability, and thus surface unevenness and wrinkles are not generated. In addition, no protective film is used in the production of the 1 st and 2 nd polarizing plates, and therefore, no defect transfer occurs.

Further, the Ra value of the B-side of the optical film is very small compared to the a-side, and the optical film and the polarizer are sufficiently bonded, so that light leakage does not occur.

In the image display device 209, the optical film used has a very high surface roughness Ra on the a-side and the B-side, and therefore has good sliding properties and does not cause surface irregularities or wrinkles, but the surface roughness Ra on the B-side is out of the preferable range, and therefore a gap is formed at the adhesion interface between the optical film and the polarizer, and light leakage occurs.

In the image display devices 210, 211, the surface roughness Ra of the B-side of the optical film used was insufficient, and therefore slight surface unevenness and wrinkles were generated in the optical film conveyance, but did not reach the level of actual damage. In addition, light leakage was not confirmed.

In the image display device 214, the optical film used has a sufficient surface roughness Ra on the a-side and the B-side, and therefore has high slidability and does not cause surface unevenness or wrinkles, but a gap is formed at the adhesion interface between the optical film and the polarizer, and significant light leakage occurs.

In the image display devices 215, 216, the surface roughness Ra of the a-side and B-side of the optical film used is insufficient, and hence significant surface unevenness and wrinkles are generated in the optical film conveyance. Therefore, the evaluation of light leakage in the image display devices 215 and 216 cannot be performed.

In addition, in the image display device 217, an optical film to which a protective film was attached was used, and a significant transfer defect was confirmed. Therefore, light leakage from the defect can be observed.

Claims

the surface conditioner contains at least one of an organosilicon material, a fluorine-based material, a vinyl-based material and an acrylic-based material,

the content of the surface conditioner is in the range of 0.01-5.0 mass% relative to all components excluding the solvent in the material forming the optical film,

the content of the fine particles is in the range of 0.5-5.0 mass% relative to the total components excluding the solvent in the material constituting the optical film,

2. The optical film of claim 1,

4. A method for producing an optical film, characterized in that the method for producing an optical film according to any one of claims 1 to 3,

5. A polarizing plate is characterized by comprising:

polarizer and

the optical film according to any one of claims 1 to 3.

6. The polarizing plate according to claim 5, wherein the polarizer is adhered to a surface having a low surface roughness Ra of both surfaces of the optical film.

7. An image display device comprising the optical film according to any one of claims 1 to 3.