JP6711364B2 - Optical film, optical film roll, and method for producing optical film - Google Patents

Description

The present invention relates to an optical film, an optical film roll body, and a method for manufacturing an optical film. More specifically, the present invention, even in a thin optical film containing a cycloolefin resin as a main component, is less likely to cause a transfer failure or a scratch failure when an optical film roll body is formed together with an inexpensive protect film. The present invention relates to an optical film which is excellent in processability after the protective film is peeled off.

From the viewpoint of production efficiency, the optical film is produced in a certain amount in a long form and stored as a roll-shaped roll (hereinafter, also referred to as an optical film roll or simply a roll). Many. There is known a technique of laminating a protect film on the optical film in order to protect the optical film and improve the handling property when the long optical film is wound.

Due to the recent tendency of thinning the optical film, the importance of the protect film is increasing from the viewpoint of protecting the optical film and preventing scratches during handling.

The protect film is often provided with an uneven structure on its surface in consideration of handleability. However, since an optical film containing a cycloolefin resin generally has a low elastic modulus and is soft, when the protective film is laminated and wound in a roll, the irregular shape (also referred to as grain) on the surface of the protective film is concerned. It has been found that there is a problem that transfer to an optical film easily occurs. The problem is more remarkable in a thin film region where the rigidity of the optical film becomes weak (for example, the film thickness is 40 μm or less).

To improve this problem, a technique has been reported in which the transfer is improved by adjusting the arithmetic average roughness Ra of the surface of the protect film (see, for example, Patent Document 1 and Patent Document 2).

However, in order to uniformly adjust and apply the arithmetic mean roughness Ra to the protect film, it is necessary to have accuracy, and therefore costly. Since the protect film is a peelable protective film which is necessary when the roll body of the optical film is formed, stored and moved, it is desirable that the protect film is inexpensive.

Further, in a polyethylene film (also referred to as PE film) which is a relatively inexpensive protect film, film defects (irregularities) due to unmelted pellets, foreign matters, burns, etc. during melt film formation are likely to occur, and these irregularities are optical. A failure called "fish eye" occurs when the film is transferred to the roll body. In order to reduce the "fisheye", it is considered that the protect film is made thick to increase the elastic modulus, but the cost increases accordingly. It is also conceivable to use a polyester film (for example, a PET film) having a high elastic modulus as the protect film, but the PET film is significantly high in cost.

Further, there is a problem that the handling property of the optical film is deteriorated after the protective film is peeled off during the processing of the optical film.

From the above, in forming an optical film roll body on which a protect film is laminated, a means for solving each of the above problems is required.

JP, 2005-125340, A JP, 2013-226809, A

The present invention has been made in view of the above problems and circumstances, and the problem to be solved is an optical film roll body together with an inexpensive protect film, even if it is a thin optical film containing a cycloolefin resin as a main component. It is an object of the present invention to provide an optical film, an optical film roll body, and a method for producing an optical film, which are less likely to cause a transfer failure or a scratch failure when forming, and have excellent processability after the protective film is peeled off.

The present inventor, in order to solve the above problems, in the process of examining the causes of the above problems, a silica particle containing a cycloolefin resin as a main component, which is a thin film, and whose surface is modified with a specific compound, is used. By the optical film containing, even if it is a thin optical film containing a cycloolefin resin as a main component, when forming an optical film roll body together with an inexpensive protect film, a transfer failure or a scratch failure is less likely to occur. It has been found that an optical film having excellent processability after peeling off the protect film can be obtained.

That is, the above-mentioned subject concerning the present invention is solved by the following means.

1. An optical film containing a cycloolefin resin as a main component and having a film thickness in the range of 5 to 40 μm, which is an alkylsilane having an alkyl group having 5 to 21 carbon atoms, dimethylsiloxane, a dimethylsiloxane cyclic body, and methacrylic acid. Roxysilane, and silica particles surface-modified with at least one compound selected from aminosilane are contained in the range of 0.1 to 5.0 mass% with respect to the total mass of the film. Optical film to do.

2 . The average particle size of the silica particles in the film is in the range of 5 to 400 nm, The optical film as described in the above item 1.

3 . An optical film roll body, which is provided with a protect film on the surface of the optical film according to item 1 or 2.

4 . It is a manufacturing method of the optical film which manufactures the optical film of Claim 1 or 2, Comprising: The said optical film is manufactured by the solution casting film forming method, The manufacturing method of the optical film characterized by the above-mentioned.

By the above means of the present invention, even in the case of a thin optical film containing a cycloolefin resin as a main component, when an optical film roll body is formed with an inexpensive protect film, a transfer failure or a scratch failure is less likely to occur, It is possible to provide an optical film, an optical film roll body, and a method for producing an optical film which are excellent in processability after the protective film is peeled off.

Although the mechanism of action or mechanism of action of the present invention has not been clarified, it is presumed as follows.

According to the study by the present inventor, in the case of a cellulose ester such as a triacetyl cellulose film (TAC film), the interaction between the resins is strong, and the silica particles contained therein are relatively easily secondary-aggregated to have a particle diameter. The silica particles form a secondary agglomerate due to low intermolecular interaction and low surface tension in the case of cycloolefin resins, although the matting effect (slipperiness and scratch prevention effect) can be exhibited. It was found that the matting effect was difficult to obtain because the primary particles simply remained dispersed in the resin.

The present invention, the cycloolefin resin film, by containing silica particles surface-modified with a compound having a long chain functional group or a cyclic functional group, the entanglement and interaction with the cycloolefin resin is improved. By making it easier to form secondary aggregates, the matting effect of the cycloolefin resin film itself is exhibited. Therefore, even if the above-mentioned inexpensive protect film is laminated to form an optical film roll body, the occurrence of "fish eye" failure is suppressed, and even when the protect film is peeled off and a polarizing plate is processed, handling is performed. It has good properties and the yield of the polarizing plate can be increased.

Further, when a melt-casting film formation method is adopted as a method for forming a cycloolefin resin film, the silica particles according to the present invention are uniformly distributed in a plane direction and a thickness direction in the layer due to the viscosity of the melt. It is difficult to include in the, but by producing by a solution casting film forming method, the dope viscosity can be adjusted, it becomes easy to uniformly disperse the silica particles, more effectively from the dispersed primary particles It has also been found that secondary aggregates can be formed.

The figure which showed typically an example of the dope preparation process, the casting process, the drying process, and the winding process of the solution casting film-forming method preferable for this invention.

The optical film of the present invention is an optical film containing a cycloolefin resin as a main component and having a film thickness in the range of 5 to 40 μm, which is an alkylsilane having a C 5-21 alkyl group, or dimethylsiloxane. Silica particles surface-modified with at least one compound selected from the group consisting of dimethylsiloxane cyclics, methacryloxysilane, and aminosilane within the range of 0.1 to 5.0% by mass relative to the total mass of the film. It is characterized by containing in. This feature is a technical feature common to the inventions according to each of claims 1 to 4 .

As an embodiment of the present invention, from the viewpoint of exhibiting the effect of the present invention, it is inexpensive to contain the silica particles in the range of 0.1 to 5.0 mass% with respect to the total mass of the film. when forming the optical film roll with protective film, transfer failure or scratch defects hardly occurs, an optical film excellent in processing suitability of after peeling off the protective film is Ru obtained.

Further, it is preferable that the average particle diameter of the silica particles in the film is within a range of 5 to 400 nm from the viewpoint of exhibiting the above-mentioned matting effect.

The optical film roll body of the present invention is preferably an embodiment in which a protective film is provided on the surface of the optical film, and when it is stored as a roll body, the protection and handling property of the optical film are improved.

The production method for producing the optical film of the present invention is preferably produced by a solution casting film formation method, because silica particles can be uniformly dispersed and a secondary aggregate can be effectively formed.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and after that as a lower limit and an upper limit.

<<Outline of the optical film of the present invention>>
The optical film of the present invention is an optical film containing a cycloolefin resin as a main component and having a film thickness in the range of 5 to 40 μm, which is an alkylsilane having a C 5-21 alkyl group, or dimethylsiloxane. Silica particles surface-modified with at least one compound selected from the group consisting of dimethyl siloxane cyclics , methacrylsilane, and aminosilane within the range of 0.1 to 5.0% by mass relative to the total mass of the film. It is characterized by containing.

Here, the “main component” means that the resin constituting the film is contained in an amount of 50% by mass or more.

The "thickness" of the film is measured with a tape-shaped sample (3 m in length) that is continuous in the film flow direction, and is commercially available (for example, electronic micrometer Millitron 1240 manufactured by Seiko EM Co., Ltd.) It is possible to obtain the average value (d) of the film thickness by measuring and averaging the thickness at 100 points at 1 cm pitch using.

<Structure of the optical film of the present invention>
The optical film of the present invention (hereinafter sometimes referred to as cycloolefin-based film) is a thin optical film containing a cycloolefin-based resin as a main component and having a film thickness in the range of 5 to 40 μm. It is preferably used as a protective film for a polarizing plate, a retardation film, or the like. When the optical film of the present invention is a λ/4 retardation film, it can be used as an antireflection film of an organic electroluminescence display device by forming a circularly polarizing plate by being attached to a polarizer. it can.

[1] Cycloolefin resin (cycloolefin polymer)
As the cycloolefin-based resin, polymers of various cycloolefin monomers can be used, but it is preferable to use polymers obtained by homopolymerizing or copolymerizing cycloolefin monomers having a norbornene skeleton. ..

Among them, it is preferable to use a polymer obtained by homopolymerizing or copolymerizing a cycloolefin monomer having a polar group in view of the interaction with the silica particles according to the present invention.

The cycloolefin monomer used in the present invention will be described below.

The cycloolefin resin according to the present invention is a polymer obtained by homopolymerization or copolymerization from the cycloolefin monomers represented by the general formulas (A-1) and (A-2) shown below. Preferably. In particular, a cycloolefin resin having a structure represented by formula (A-2) is preferable from the viewpoint of facilitating the formation of a secondary aggregate due to the interaction between the polar group of the resin and the silica particles. ..

The cycloolefin monomer having the structure represented by formula (A-1) will be described.

（一般式（Ａ−１）中、Ｒ^１〜Ｒ^４は、それぞれ独立に水素原子又はハロゲン原子を表す。又は、酸素原子、窒素原子、イオウ原子若しくはケイ素原子を含む連結基を有していてもよい、置換又は非置換の炭素原子数１〜３０の炭化水素基、若しくは極性基を表す。ｐは、０〜２の自然数を表す。）
上記極性基は、酸素、硫黄、窒素、ハロゲンなど電気陰性度の高い原子によって分極が生じている官能基のことをいう。上記極性基としては、カルボキシ基、ヒドロキシ基、アルコキシカルボニル基、アリールオキシカルボニル基、アミノ基、アミド基、シアノ基、ハロゲン原子などが挙げられ、これら極性基はメチレン基などの連結基を介して結合していてもよい。また、酸素原子、窒素原子、イオウ原子又はケイ素原子を含む連結基を有していてもよい置換又は非置換の炭素原子数１〜３０の炭化水素基、例えばカルボニル基、エーテル基、シリルエーテル基、チオエーテル基、イミノ基など極性を有する２価の有機基が連結基となって結合している炭素原子数１〜３０の炭化水素基なども極性基として挙げられる。これらの中では、カルボキシ基、ヒドロキシ基、アルコキシカルボニル基又はアリールオキシカルボニル基が好ましく、特にアルコキシカルボニル基又はアリールオキシカルボニル基であることが、溶液製膜時の溶解性を確保する観点で好ましい。

(In the general formula (A-1), R ^{1 to} R ⁴ each independently represent a hydrogen atom or a halogen atom. Or, they have a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom. May represent a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, or a polar group, and p represents a natural number of 0 to 2.)
The polar group means a functional group in which polarization is caused by an atom having a high electronegativity such as oxygen, sulfur, nitrogen and halogen. Examples of the polar group include a carboxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, a cyano group, a halogen atom and the like, and these polar groups are linked via a connecting group such as a methylene group. May be combined. Further, a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, which may have a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom, for example, a carbonyl group, an ether group, a silyl ether group. The polar group may also be a hydrocarbon group having 1 to 30 carbon atoms in which a divalent organic group having polarity such as a thioether group and an imino group serves as a linking group and is bonded. Of these, a carboxy group, a hydroxy group, an alkoxycarbonyl group or an aryloxycarbonyl group is preferable, and an alkoxycarbonyl group or an aryloxycarbonyl group is particularly preferable from the viewpoint of ensuring the solubility during solution film formation.

Next, the cycloolefin monomer represented by formula (A-2), which is preferable in the present invention, will be described.

（一般式（Ａ−２）中、Ｒ^５は、独立に水素原子、炭素数１〜５の炭化水素基、又は炭素数１〜５のアルキル基を有するアルキルシリル基を表す。Ｒ^６は、カルボキシ基、ヒドロキシ基、アルコキシカルボニル基、アリールオキシカルボニル基、アミノ基、アミド基、シアノ基、フッ素原子、塩素原子、臭素原子、又はヨウ素原子を表す。ｐは、０〜２の整数を表す。）
本発明においては、一般式（Ａ−２）で表されるように、置換基Ｒ^５及びＲ^６が片側炭素に置換されたシクロオレフィン単量体を用いることで、分子の対称性が崩れたためか溶媒揮発時の樹脂の拡散運動を促進し、それに伴い樹脂の極性基がシリカ粒子と相互作用が強まり、二次凝集体を形成しやすくする観点から、好ましい。

(In the general formula (A-2), R ⁵ independently represents 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. R ⁶ represents It represents a carboxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and p represents an integer of 0 to 2. )
In the present invention, as represented by the general formula (A-2), by using a cycloolefin monomer in which the substituents R ⁵ and R ⁶ are substituted on one side carbon, the symmetry of the molecule is broken. It is preferable from the viewpoint of facilitating the diffusion movement of the resin when the solvent is volatilized, and the polar group of the resin is strengthened in the interaction with the silica particles to facilitate the formation of secondary aggregates.

R ⁵ is preferably a hydrocarbon group having 1 to 3 carbon atoms, R ⁶ is preferably a carboxy group, a hydroxy group, an alkoxycarbonyl group or an aryloxycarbonyl group, and particularly preferably an alkoxycarbonyl group or an aryloxycarbonyl group. In addition to the effects of the invention, it is preferable from the viewpoint of ensuring the solubility during solution casting.

The structures of the general formulas (A-1) and (A-2) in the present application are specifically shown below, but are not limited to the following specific examples.

Examples of the copolymerizable monomer copolymerizable with the cycloolefin monomer include a copolymerizable monomer capable of ring-opening copolymerization with the cycloolefin monomer, and addition copolymerization with the cycloolefin monomer. Possible copolymerizable monomers and the like are included.

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

Examples of the copolymerizable monomer capable of addition copolymerization include unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, and (meth)acrylates. Examples of the unsaturated double bond-containing compound include olefin compounds having 2 to 12 carbon atoms (preferably 2 to 8), and examples thereof include ethylene, propylene, butene and the like. Examples of the vinyl-based cyclic hydrocarbon monomer include vinyl-cyclopentene-based monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. Examples of (meth)acrylates 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 ratio of the cycloolefin monomer in the copolymer of the cycloolefin monomer and the copolymerizable monomer is, for example, 20 to 80 mol% with respect to the total of all the monomers constituting the copolymer, It may preferably be 30 to 70 mol %.

The cycloolefin resin is a polymer obtained by homopolymerizing or copolymerizing a cycloolefin monomer having a norbornene skeleton and having a structure represented by the general formulas (A-1) and (A-2). There are the following, for example.
(1) Ring-opening polymer of cycloolefin monomer (2) Ring-opening copolymer of cycloolefin monomer and copolymerizable monomer (3) Ring-opening polymer (1) or (2) above Hydrogenated (co)polymer of (co)polymer (4) The ring-opened (co)polymer of (1) or (2) above was cyclized by Friedel-Crafts reaction and then hydrogenated (co)polymer (5) Saturated polymer of cycloolefin monomer and unsaturated double bond-containing compound (6) Addition type (co)polymer of cycloolefin monomer and hydrogenated (co)polymer thereof (7) Alternating Copolymer of Cycloolefin Monomer and Methacrylate or Acrylate The polymers of (1) to (7) are all known methods, for example, JP 2008-107534 A and JP 2005-227606 A. It can be obtained by the method described in the publication. For example, as the catalyst and solvent used in the above-mentioned (2) ring-opening copolymerization, those described in paragraphs 0019 to 0024 of JP-A-2008-107534 can be used. As the catalyst used in the hydrogenation of (3) and (6), for example, those described in paragraphs 0025 to 0028 of JP-A-2008-107534 can be used. As the acidic compound used in the above Friedel-Crafts reaction (4), for example, those described in paragraph 0029 of JP-A-2008-107534 can be used. As the catalyst used in the addition polymerization of the above (5) to (7), for example, those described in paragraphs 0058 to 0063 of JP-A-2005-227606 can be used. The alternating copolymerization reaction of (7) above can be carried out, for example, by the method described in paragraphs 0071 and 0072 of JP-A-2005-227606.

Among them, the polymers of (1) to (3) and (5) above are preferable, and the polymers of (3) and (5) above are more preferable.

Preferred cycloolefin polymers according to the present invention include those having a structural unit represented by the following general formula (B-1) or general formula (B-2). Such a cycloolefin-based resin includes only the structural unit represented by the general formula (B-1), only the structural unit represented by the general formula (B-2), the general formula (B-1) and the general formula (B-1). It may be a copolymer containing each structural unit of B-2).

Preferably, it is a resin having a structure of the general formula (B-2) alone or a copolymer containing structural units of both the general formula (B-1) and the general formula (B-2). It is preferable because the obtained cycloolefin resin has a high glass transition temperature and an excellent transmittance.

（一般式（Ｂ−１）中、Ｘは、−ＣＨ＝ＣＨ−で表される基又は−ＣＨ_２ＣＨ_２−で表される基である。Ｒ^１〜Ｒ^４は、それぞれ独立に水素原子又はハロゲン原子を表す。又は、酸素原子、窒素原子、イオウ原子若しくはケイ素原子を含む連結基を有していてもよい、置換又は非置換の炭素原子数１〜３０の炭化水素基、若しくは極性基を表す。ｐは、０〜２の自然数を表す。）

(In the general formula (B-1), X is -CH = CH- a group represented by or ^{_{-CH 2 CH 2 - .R 1 ~R}} 4 is a group represented by are independently a hydrogen atom Or a halogen atom, or a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, or a polar group which may have a connecting group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom. Represents, and p represents a natural number of 0 to 2.)

（一般式（Ｂ−２）中、Ｘは、−ＣＨ＝ＣＨ−で表される基又は−ＣＨ_２ＣＨ_２−で表される基である。Ｒ^５は、それぞれ独立に水素原子、炭素数１〜５の炭化水素基、又は炭素数１〜５のアルキル基を有するアルキルシリル基を表す。Ｒ^６は、カルボキシ基、ヒドロキシ基、アルコキシカルボニル基、アリールオキシカルボニル基、アミノ基、アミド基、シアノ基、フッ素原子、塩素原子、臭素原子、又はヨウ素原子を表す。ｐは、０〜２の整数を表す。）
本明細書では、本願に係るシクロオレフィン系樹脂の製造方法等については、特開２００８−１０７５３４号公報の記載を援用するものとし、その説明を省略する。
シクロオレフィン系樹脂は１種単独で、又は２種以上を併用することができる。

(In the general formula (B-2), X is a group or _-CH 2 CH ₂ represented by -CH = CH- - a group represented by .R ⁵ each independently represent a hydrogen atom, the number of carbon atoms Represents a hydrocarbon group having 1 to 5 or an alkylsilyl group having an alkyl group having 1 to 5 carbon atoms, R ⁶ represents a carboxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, Represents a cyano group, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and p represents an integer of 0 to 2.)
In this specification, the description of Japanese Patent Application Laid-Open No. 2008-107534 is incorporated by reference for the method for producing a cycloolefin resin according to the present application, and the description thereof is omitted.
The cycloolefin resins can be used alone or in combination of two or more.

The preferred molecular weight of the cycloolefin resin according to the present invention is a polystyrene-equivalent number average molecular weight (Mn) measured by the following gel permeation chromatography (GPC) of 8,000 to 100,000, more preferably 10,000 to 80,000, and particularly preferably 12,000. The weight average molecular weight (Mw) is preferably 20,000 to 300,000, more preferably 30,000 to 250,000, and particularly preferably 40,000 to 200,000.

The weight average molecular weight Mw and the number average molecular weight Mn are measured using gel permeation chromatography (GPC).

The measurement conditions are as follows.

Solvent: Dichloromethane Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko KK)
Column temperature: 25°C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml/min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw=500 to 1,000,000 A calibration curve of 13 samples was used. The 13 samples are used at substantially equal intervals.

By having the number average molecular weight and the weight average molecular weight in the above range, heat resistance of the cycloolefin resin, water resistance, chemical resistance, mechanical properties, and molding processability as the cycloolefin film of the present invention are good. Become.

The glass transition temperature (Tg) of the cycloolefin resin according to the present invention is usually 110°C or higher, preferably 110 to 350°C, more preferably 120 to 250°C, and particularly preferably 120 to 220°C. It is preferable that the Tg is 110° C. or higher because deformation is less likely to occur due to use under high temperature conditions or secondary processing such as coating and printing.

On the other hand, by setting the Tg to 350° C. or less, it is possible to avoid the case where the molding process becomes difficult and suppress the possibility that the resin is deteriorated by the heat during the molding process.

The cycloolefin-based resin is a specific hydrocarbon-based resin described in JP-A-9-221577 or JP-A-10-287732, or a known heat-resistant resin within a range that does not impair the effects of the present invention. Plastic resins, thermoplastic elastomers, rubbery polymers, organic fine particles, inorganic fine particles and the like may be blended, and specific wavelength dispersants, plasticizers, antioxidants, release accelerators, rubber particles, ultraviolet absorbers, etc. You may include an additive.

Further, as the cycloolefin-based resin, a commercially available product can be preferably used, and examples of the commercially available products include JSR Corporation's ARTON (registered trademark) G, ARTON F, ARTON R, and ARTON RX product names. It has been released in and can be used.

[2] Silica particles The silica particles according to the present invention are particles containing silicon dioxide as a main component. The main component means that it contains 50% or more of the components constituting the particles, preferably 70% or more, more preferably 80% or more, particularly preferably 90% or more.

The silica particles according to the present invention are composed of at least one compound selected from alkylsilanes having an alkyl group having 5 to 21 carbon atoms represented by the following structural formula, dimethylsiloxane, dimethylsiloxane cyclics, methacryloxysilane, and aminosilane. The silica particles are surface-modified.

By containing silica particles surface-modified with a compound having such a long-chain functional group or cyclic functional group, entanglement and interaction with the cycloolefin resin are improved to form a secondary aggregate. By making it easier, the matte effect of the cycloolefin resin film itself is exhibited. Therefore, even if the above-mentioned inexpensive protect film is laminated to form an optical film roll body, the occurrence of "fish eye" failure is suppressed, and even when the protect film is peeled off and a polarizing plate is processed, handling is performed. It has good properties and the yield of the polarizing plate can be increased.

Further, it is preferable that the surface of the silica particles is subjected to a hydrophobic treatment, because the dispersibility of the silica particles in a solvent is improved and the generation of foreign matter can be suppressed.

The degree of hydrophobization on the surface of silica particles can be quantified by the following methanol wettability method, and it can be determined whether the particles are silica particles according to the present invention.

<Methanol wettability method>
In a mixed solution of methanol and pure water, while changing the mixing ratio of methanol to pure water, the same amount (the same volume) of silica particles was added to each solution and mixed by stirring, and each mixed solution was centrifuged. Separately, the volume of the sediment of the silica particles is obtained, and it means the methanol mixing ratio of the solution in which the volume of the sediment of the silica particles in the solution becomes 50%.

When the mixing ratio of methanol is 50% by volume or more, the silica particles are judged to meet the object of the present invention.

For example, a plurality of solutions having different ratios of methanol to pure water are prepared, and the volume of sediment of silica fine particles to be measured is 2.5 mL, and the volume of silica particles added first is 5 mL. Is 50% by volume or more, the silica particles are judged to be the silica particles subjected to the hydrophobic surface modification in the present invention.

The average particle size of the primary particles of the silica particles is preferably in the range of 5 to 400 nm, more preferably 7 to 300 nm.

The average particle size of the secondary particles of the silica particles, that is, the average particle size in the film, is preferably in the range of 100 to 400 nm from the viewpoint of preventing scratches during transfer or handling of the protect film. Further, when the average particle diameter of the primary particles is within the range of 100 to 400 nm, it is also preferable that the primary particles are contained as primary particles without being aggregated.

<Measurement method of average particle size of silica particles>
The particle size of the silica particles in the optical film is measured by taking a cross-section of the film cut by a microtome with a scanning electron microscope (SEM) at an appropriate magnification to obtain 100 particles included in the cut-to-cut photograph. The particle size of is measured, and the average value is calculated and used as the average particle size. The particle diameter is the diameter when the cross section of the particle is circular, and is the diameter when the area is calculated and converted into a circular shape when it is not circular.

SEM: JSM-6060LA (JEOL: JEOL Ltd.)
Microtome: Leica EM UC6
The content of silica particles in the film is in the range of 0.1 to 5.0 mass% with respect to the total mass of the film, and preferably in the range of 0.5 to 3.0 mass %. It is particularly preferable that the content is in the range of 1.0 to 2.5 mass% in order to form the secondary aggregate and to exhibit the effect of the present invention.

As the silica particles according to the present invention, commercially available products can be preferably used, and the product Aerizil series manufactured by Nippon Aerosil Co., Ltd. described below is suitable (the surface modifier is shown in parentheses).

R805 (octylsilane), R816 (hexadecylsilane), NKC130 (dimethylsiloxane), R711, R7200 (or more, methacryloxysilane), R202, RY200, RY200S, RY300 (or more, dimethylsiloxane), R104, R105 (or more, Dimethylsiloxane cyclic compound), RA200H, RA200HS (above, aminosilane) (above, hydrophobic Aerosil manufactured by Nippon Aerosil Co., Ltd.) are commercially available and can be used.

Among these, Aerosil R816, NKC130 and RY300 are preferable because they can improve the handling property during handling and keep the haze of the optical film low.

The optical film of the present invention preferably contains silica particles and has a dynamic friction coefficient of at least one surface within a range of 0.2 to 1.0. The dynamic friction coefficient can be measured according to "JIS K7125 plastic-film and sheet friction coefficient test method".

Examples of the method for adding the silica particles according to the present invention include the following first to third methods, but any method may be used.

[First addition method]
After the solvent and the particles are mixed by stirring, dispersion is performed using a disperser, and this is added to the dope and stirred to obtain a cast dope.

[Second addition method]
After the solvent and the particles are mixed by stirring, they are dispersed using a disperser to prepare a particle dispersion. Next, a small amount of resin is added to a solvent, and the mixture is stirred and dissolved, and the above particle dispersion is added and stirred, and then this is added to the raw material dope liquid and sufficiently mixed to obtain a casting dope.

[Third addition method]
After a small amount of resin is added to the solvent and dissolved by stirring, particles are added and dispersed using a disperser. Add this to the dope and mix well.

The silica particles contained in the completed casting dope may be contained in the regenerated film when the regenerated film is used for the preparation of the dope. The extended dope is preferably according to the present invention.

[3] Other Additives The cycloolefin film of the present invention may contain a retardation increasing agent, a plasticizer, an antioxidant, a light stabilizer, an antistatic agent, a release agent and the like. The details of major additives are described below.

[3.1] Retardation enhancer The retardation enhancer referred to in the present application means a retardation value Rt in the thickness direction of a cycloolefin film containing 3 parts by mass of the compound with respect to 100 parts by mass of the cycloolefin resin. It refers to a compound having a function (measured at a light wavelength of 590 nm) of 1.1 times or more that of a non-added cycloolefin film.

The retardation increasing agent used in the present invention is not particularly limited and is, for example, a conventionally known disc having an aromatic ring described in JP-A 2006-113239, paragraphs [0143] to [0179]. Compounds (1,3,5-triazine compounds, etc.), rod-shaped compounds described in JP-A 2006-113239, paragraphs [0106] to [0112], JP-A-2012-214682, paragraphs [0118] to [0133]. The described pyrimidine compounds and the like can be used. The amount added to the cycloolefin resin is also adjusted within the range described in the above publication.

[3.2] Plasticizer In the present invention, a polyester resin may be used as a plasticizer. The polyester resin is obtained by polymerizing a dicarboxylic acid and a diol, and 70% or more of the dicarboxylic acid structural unit (dicarboxylic acid-derived structural unit) is derived from an aromatic dicarboxylic acid and the diol structural unit (derived from the diol). 70% or more of the constituent units are derived from the aliphatic diol.

The polyester resin is preferably added in an amount of 1 to 20% by mass, more preferably 3 to 15% by mass, and further preferably 5 to 10% by mass with respect to 100 parts by mass of the cycloolefin resin. be able to.

The ratio of the structural unit derived from the aromatic dicarboxylic acid is 70% or more, preferably 80% or more, more preferably 90% or more.

The proportion of the constituent units derived from the aliphatic diol is 70% or more, preferably 80% or more, more preferably 90% or more. Two or more polyester resins may be used in combination.

As the aromatic dicarboxylic acid, naphthalenedicarboxylic acid such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid and 2,7-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid , 3,4′-biphenyldicarboxylic acid and the like, and ester-forming derivatives thereof.

As the polyester resin, aliphatic dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid, and monocarboxylic acids such as benzoic acid, propionic acid and butyric acid can be used as long as the object of the present invention is not impaired.

Examples of the aliphatic diol include ethylene glycol, 1,3-propylene diol, 1,4-butane diol, 1,4-cyclohexane dimethanol, 1,6-hexane diol, and ester-forming derivatives thereof.

As the polyester resin, monoalcohols such as butyl alcohol, hexyl alcohol, and octyl alcohol, and polyhydric alcohols such as trimethylolpropane, glycerin, and pentaerythritol can be used as long as the object of the present invention is not impaired.

Known methods such as a direct esterification method and a transesterification method can be applied to the production of the polyester resin. Examples of the polycondensation catalyst used in the production of the polyester resin include known antimony trioxide, antimony compounds such as antimony pentoxide, germanium compounds such as germanium oxide, titanium compounds such as titanium acetate, and aluminum compounds such as aluminum chloride. Yes, but not limited to.

Preferred polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polyethylene-2,6-naphthalenedicarbochelate resin, polyethylene-2, 6-naphthalene dicarboxylate-terephthalate copolymer resin, polyethylene-terephthalate-4,4'-biphenyldicarboxylate resin, poly-1,3-propylene-terephthalate resin, polybutylene terephthalate resin, polybutylene-2,6-naphthalene There are dicarboxylate resins and the like.

More preferable polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polybutylene terephthalate resin and polyethylene-2,6-naphthalene dicarboxylate. A resin may be used.

The intrinsic viscosity of the polyester resin (value measured at 25° C. in phenol/1,1,2,2-tetrachloroethane=60/40 mass ratio mixed solvent) is in the range of 0.7 to 2.0 cm ³ /g. Is preferable, and more preferably within the range of 0.8 to 1.5 cm ³ /g. When the intrinsic viscosity is 0.7 cm ³ /g or more, the molecular weight of the polyester resin is sufficiently high, so that a molded article made of the polyester resin composition obtained by using the polyester resin has mechanical properties required as a molded article. At the same time, the transparency becomes good. When the intrinsic viscosity is 2.0 cm ³ /g or less, the moldability becomes good. As the other plasticizer, compounds described in the general formula (PEI) and the general formula (PEII) in paragraphs 0056 to 0080 of JP2013-97279A may be used.

[3.3] Ultraviolet absorber The cycloolefin-based film of the present invention preferably contains an ultraviolet absorber in order to shield unnecessary ultraviolet rays irradiated to the polarizing plate and the liquid crystal display device.

Examples of the ultraviolet absorber include oxybenzophenone-based compounds, benzotriazole-based compounds, salicylic acid ester-based compounds, benzophenone-based compounds, cyanoacrylate-based compounds, nickel complex salt-based compounds, and the like, but less colored benzotriazole-based compounds Compounds are preferred. Further, the ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574, and the polymer ultraviolet absorber described in JP-A-6-148430 are also preferably used.

When the cycloolefin-based film of the present invention is used as a protective film for a polarizing plate in addition to an optical compensation film, the ultraviolet absorber has an ability to absorb ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of a polarizer or liquid crystal. From the viewpoint of excellent display property of liquid crystal and absorption of visible light having a wavelength of 400 nm or more, it is preferable.

The addition amount of the ultraviolet absorber is preferably in the range of 0.1 to 5.0 mass% with respect to the cycloolefin resin, and more preferably in the range of 0.5 to 5.0 mass %. preferable.

Examples of the benzotriazole-based ultraviolet absorber useful in the present invention include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2-(2'-hydroxy-3',5'-di-t. -Butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butyl Phenyl)-5-chlorobenzotriazole, 2-[2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthalimidomethyl)-5'-methylphenyl]benzotriazole, 2,2 -Methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], 2-(2'-hydroxy-3'-t-butyl-5 '-Methylphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazol-2-yl)-6-(linear and side chain dodecyl)-4-methylphenol, octyl-3-[3-t- Butyl-4-hydroxy-5-(chloro-2H-benzotriazol-2-yl)phenyl]propionate and 2-ethylhexyl-3-[3-t-butyl-4-hydroxy-5-(5-chloro-2H- Examples thereof include a mixture of benzotriazol-2-yl)phenyl]propionate, but are not limited thereto.

Further, as commercially available products, "TINUVIN 109", "TINUVIN 171", "TINUVIN 326", "TINUVIN 328", "TINUVIN 928", "TINUVIN" are available. ) 812” (above, trade name, manufactured by BASF Japan Ltd.) can be preferably used.

[3.4] Antioxidant The antioxidant delays or prevents decomposition of the base film due to, for example, halogen as a residual solvent in the base film or phosphoric acid as a phosphoric acid plasticizer. Therefore, it is preferable to contain an appropriate amount in the film.

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

In particular, 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)propionate] is preferred. Further, for example, a hydrazine-based metal deactivator such as N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine or tris(2,4-di-). A phosphorus-based processing stabilizer such as t-butylphenyl)phosphite may be used in combination.

[4] Method for producing cycloolefin film The cycloolefin film of the present invention is preferably a film produced by a solution casting film forming method. When a melt-casting film forming method is adopted as a method for forming a cycloolefin resin film, the silica particles according to the present invention are uniformly contained in a plane direction and a thickness direction in the layer due to the viscosity of the melt and the like. It is difficult to do so, but by producing by the solution casting film forming method, the dope viscosity can be adjusted, the silica particles can be easily dispersed uniformly, and the secondary particles can be effectively dispersed from the dispersed primary particles. From the viewpoint of being able to form aggregates, it is a preferred film forming method.

The cycloolefin-based film of the present invention comprises a step of preparing a dope containing at least a cycloolefin-based resin, silica particles and an organic solvent (dope preparation step), and casting the dope on a support to form a web (casting). (Also referred to as a film), a step of casting (casting step), a step of evaporating the solvent from the web on the support (solvent evaporation step), a step of peeling the web from the support (peeling step), the obtained film Drying step (preliminary drying step), stretching the film (stretching step), further drying the stretched film (main drying step), winding the obtained cycloolefin-based film (winding step) It is preferable that it is manufactured by Further, in the present invention, in the winding step of the cycloolefin-based film, it is preferable to wind the protective film together with the protect film so that the protect film is in contact with the surface of the cycloolefin-based film.

The above steps will be described with reference to the drawings.

FIG. 1 is a diagram schematically showing an example of a dope preparing step, a casting step, a drying step and a winding step of a solution casting film forming method preferable for the present invention.

When the silica particles according to the present invention are used, the fine particle dispersion liquid in which the solvent and the silica particles are dispersed by the disperser passes from the charging pot 41 through the filter 44 and is stocked in the stock pot 42. On the other hand, the cycloolefin-based resin, which is the main dope, is dissolved together with the solvent in the melting pot 1, and the silica particles stored in the stock pot 42 are appropriately added and mixed to form the main dope. The obtained main dope is filtered by the filter 6 from the filter 3 and the stock kettle 4, the additive is added by the confluent pipe 20, mixed by the mixer 21, and sent to the pressure die 30.

On the other hand, an additive (for example, an ultraviolet absorber, a retardation increasing agent, etc.) is dissolved in a solvent, passes through a filter 12 from an additive charging pot 10 and is stocked in a stock pot 13. Then, it is mixed with the main dope by the confluence pipe 20 and the mixer 21 through the filter 15 and the conduit 16.

The main dope liquid-fed to the pressure die 30 is cast on a metal belt-shaped support 31 to form a web 32, and is peeled at a peeling position 33 after predetermined drying to obtain a film. The peeled web 32 is dried by a pre-drying device while passing through a number of conveyance rollers until a predetermined residual solvent amount is reached, and then stretched by a stretching device 34 in the longitudinal direction or the width direction. After stretching, the film is dried while passing through the transport roller 36 until it reaches a predetermined residual solvent amount by the main drying device 35, and is wound into a roll shape by the winding device 37 together with the protect film fed from the protect film roll 38. ..

Hereinafter, each step will be described.

(1) Dope preparation step The cycloolefin resin, silica particles, and in some cases, the phase difference increasing agent or other compound is dissolved in an organic solvent mainly containing a good solvent for the cycloolefin resin while stirring. Is a step of preparing a dope, or a step of mixing the cycloolefin resin solution with the silica particles, the retardation increasing agent or other compound solution to prepare a dope as a main solution.

When the cycloolefin-based film of the present invention is produced by the solution casting method, the organic solvent useful for forming the dope must simultaneously dissolve the cycloolefin-based resin, the retardation increasing agent and other compounds. Is preferred.

The following solvents are preferably used as the organic solvent used.

The aromatic solvent is preferably toluene, xylene, styrene, benzene, or a mixed solvent thereof. Of these, toluene is preferable.

In addition, toluene or the like may be added to a commercially available cycloolefin resin as a solvent for synthesizing a resin, and in that case, it is treated as an aromatic organic solvent according to the present invention.

The halogen-based solvent is preferably a chlorine-based solvent such as chloroform, dichloromethane or 1,2 dichloroethane. Of these, dichloromethane is preferable.

The non-aromatic solvent (excluding halogen solvents) is preferably selected from isopropanol, octane, acetone, ethyl formate, 1-butanol, ethyl acetate and cyclohexane.

These solvents may be used alone or in combination of two or more.

Further, alcohol solvents such as methanol, ethanol, n-butanol and 2-butanol; organic solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl sulfoxide, dioxane, cyclohexanone, tetrahydrofuran, methyl ethyl ketone (MEK) and diethyl ether. Can also be used within a range that does not impair the effects of the present invention.

The organic solvent used in the present invention is preferably a mixed solvent of a good solvent and a poor solvent, and examples of the good solvent include dichloromethane as a halogen-based solvent. The good solvent is preferably used in an amount of 55% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, based on the total amount of the solvent.

The poor solvent is preferably selected from a non-aromatic solvent, and the non-aromatic solvent selected from acetone or ethyl acetate improves the peelability and enables high speed casting. From the viewpoint of When the ratio of the non-aromatic solvent in the dope is high, the web is gelled and peeling from the metal support is facilitated, which is preferable. From the viewpoint of enhancing the planarity of the obtained cycloolefin film, it is preferable to use a dope having a non-aromatic solvent concentration in the range of 0.5 to 30 mass% to form the film.

In addition, it is also preferable to use the above alcohol solvent, and it is preferable to use ethanol among them.

Cycloolefin-based resin, silica particles, in some cases a retardation increasing agent, to dissolve other compounds, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent , JP-A-9-95544, JP-A-9-95557, or JP-A-9-95538, a method of performing a cooling dissolution method, and a high pressure described in JP-A-11-21379. Although various dissolution methods such as the method of performing may be used, the method of performing at normal pressure is preferable.

The concentration of the cycloolefin resin in the dope is preferably in the range of 10-40% by mass. After the compound is added to the dope during or after the dissolution to dissolve and disperse it, it is filtered with a filter medium, defoamed, and sent to the next step by a liquid sending pump.

Regarding the filtration of the dope, it is preferable to filter the dope with a filter medium having a leaf disc filter, for example, with a filter medium having a 90% collection particle size of 10 to 100 times the average particle size of the fine particles. ..

In the present invention, the filter material used for filtration preferably has a small absolute filtration accuracy, but if the absolute filtration accuracy is too small, clogging of the filter material easily occurs, and the filter material must be frequently replaced. However, there is a problem of reducing productivity.

Therefore, in the present invention, the filter medium used for the cycloolefin resin dope preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably 0.001 to 0.008 mm, and even more preferably 0.003 to 0. More preferred is a filter medium in the range of 006 mm.

There is no particular limitation on the material of the filter medium, and a normal filter medium can be used, but a filter medium made of plastic fiber such as polypropylene or Teflon (registered trademark) or a metal filter medium such as stainless fiber may be removed. There is no and is preferable.

In the present invention, the dope flow rate during filtration is preferably 10 to 80 kg/(h·m ² ) and more preferably 20 to 60 kg/(h·m ² ). Here, if the dope flow rate during filtration is 10 kg/(h·m ² ) or more, efficient productivity is achieved, and the dope flow rate during filtration is within 80 kg/(h·m ² ). In this case, the pressure applied to the filter medium becomes appropriate and the filter medium is not damaged, which is preferable.

The filtration pressure is preferably 3500 kPa or less, more preferably 3000 kPa or less, and further preferably 2500 kPa or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and filtration area.

In many cases, the main dope may contain about 10 to 50% by mass of recycled material.

Recycled material is, for example, a product obtained by finely crushing a cycloolefin film, which occurs when the cycloolefin film is formed, and has both side parts cut off, and scratches etc. exceed the specified value of the film. A cycloolefin film stock is used.

Further, as the raw material of the resin used for preparing the dope, those obtained by pelletizing cycloolefin resin and other compounds in advance can also be preferably used.

(2) Casting step (2-1) Casting of dope An endless metal support 31 that feeds the dope to the pressure die 30 through a liquid feed pump (for example, a pressure-type metering gear pump) and transfers it indefinitely. For example, it is a step of casting the dope from a pressure die slit at a casting position on a metal support such as a stainless belt or a rotating metal drum.

The metal support in the casting step is preferably one whose surface is mirror-finished, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support. The cast width may be in the range of 1 to 4 m, preferably 1.3 to 3 m, and more preferably 1.5 to 2.8 m. The surface temperature of the metal support in the casting step is set in the range of -50°C to a temperature at which the solvent does not boil and foam, more preferably -30 to 0°C. A higher temperature is preferable because the drying speed of the web (the dope is cast on the casting support and the formed dope film is referred to as the web) can be increased, but if the temperature is too high, the web foams, The flatness may deteriorate. The temperature of the support is preferably 0 to 100°C, and more preferably 5 to 30°C. Alternatively, it is also a preferable method that the web is gelated by cooling and peeled from the drum in a state of containing a large amount of residual solvent.

The method of controlling the temperature of the metal support is not particularly limited, but there are a method of blowing hot air or cold air and a method of bringing hot water into contact with the back side of the metal support. It is preferable to use warm water because the heat can be efficiently transferred, so that the time until the temperature of the metal support becomes constant is short. When using hot air, in consideration of the temperature drop of the web due to the latent heat of evaporation of the solvent, while using hot air above the boiling point of the solvent, it may be possible to use air at a temperature higher than the target temperature while also preventing foaming. .. In particular, it is preferable to change the temperature of the support and the temperature of the drying air during the period from casting to peeling to efficiently perform the drying.

The temperature of the dope to be cast (cast) is preferably 20°C to 35°C from the viewpoint of evenness of the film, drying property, additives, and silica particles.

The die is preferably a pressure die capable of adjusting the slit shape of the die base portion and easily making the film thickness uniform. The pressure die includes a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film formation speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and laminated.

(2-2) Solvent Evaporation Step This is a step of heating the web on the casting support to evaporate the solvent, and a step of controlling the residual solvent amount at the time of peeling described later.

To evaporate the solvent, there are a method of blowing air from the web side, a method of transferring heat from the back surface of the support by a liquid, a method of transferring heat from the front and back sides by radiant heat, etc. Is preferable and preferable. A method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 30 to 100°C. In order to maintain the atmosphere at 30 to 100° C., it is preferable to apply hot air of this temperature to the upper surface of the web or heat it by means such as infrared rays.

From the viewpoint of surface quality, moisture permeability, and releasability, it is preferable to peel the web from the support within 30 to 180 seconds.

(2-3) Peeling step This is a step of peeling the web, in which the solvent is evaporated on the metal support, at the peeling position. The peeled web is sent to the next step as a film.

The temperature at the peeling position on the metal support is preferably in the range of 10 to 40°C, more preferably 11 to 30°C.

In the present invention, the solvent in the web is evaporated in the solvent evaporation step, but the residual solvent amount of the web on the metal support at the time of peeling is preferably in the range of 15 to 100% by mass. The amount of residual solvent is preferably controlled by the drying temperature and the drying time in the solvent evaporation step.

When the amount of the residual solvent is 15% by mass or more, during the drying process on the support, the silica particles do not have a distribution in the thickness direction and are uniformly dispersed in the film. It is possible to easily suppress the deformation of the winding shape. Further, the drying time is not lengthened and the productivity is improved.

Further, when the residual solvent amount is 100% by mass or less, the film has self-supporting property, it is possible to avoid peeling defects of the film, and the mechanical strength of the web can be maintained, so that the flatness at the time of peeling is improved, It is possible to suppress the generation of cracks and vertical stripes due to peeling tension.

The amount of residual solvent in the web or film is defined by the following formula (Z).

Formula (Z)
Amount of residual solvent (%)=(mass before heat treatment of web or film-mass after heat treatment of web or film)/(mass after heat treatment of web or film)×100
Note that the heat treatment for measuring the amount of residual solvent means performing heat treatment at 115° C. for 1 hour.

The peeling tension when peeling the web from the metal support to form a film is usually in the range of 196 to 245 N/m, but when wrinkles are easily formed during peeling, peeling is performed with a tension of 190 N/m or less. Preferably.

In the present invention, the temperature at the peeling position on the metal support is preferably within the range of −50 to 40° C., more preferably within the range of 10 to 40° C., and within the range of 15 to 30° C. Is most preferred.

(3) Drying and Stretching Step The drying step may be divided into a preliminary drying step (first drying step) and a main drying step (second drying step).

(3-1) Preliminary Drying Step The film obtained by peeling the web from the metal support is preliminarily dried. Preliminary drying of the film may be carried out by transporting the film by a large number of rollers arranged above and below, or by fixing both ends of the film with clips like a tenter dryer also serving as a stretching device 34 described later. It may be dried while being transported.

The means for drying the web is not particularly limited, and generally, hot air, infrared rays, a heating roller, microwaves or the like can be used, but hot air is preferable in terms of simplicity.

The drying temperature in the web pre-drying step is preferably the glass transition point of the film of −5° C. or lower, and it is effective to perform heat treatment at a temperature of 30° C. or higher for 1 minute to 30 minutes. The drying temperature is 40 to 150° C., more preferably 50 to 100° C.

(3-2) Stretching step The cycloolefin-based film of the present invention is stretched in a stretching device 34 under a residual solvent amount to improve the flatness of the film or control the orientation of molecules in the film. By doing so, desired phase difference values Ro and Rt can be obtained.

In the method for producing a cycloolefin film of the present invention, in the step of stretching the film, the residual solvent amount at the start of stretching is preferably 1% by mass or more and less than 15% by mass. More preferably, it is within the range of 2 to 10% by mass.

The optical film of the present invention is preferably stretched in the longitudinal direction (also referred to as MD direction and casting direction) and/or the width direction (also referred to as TD direction), and/or the oblique direction, and at least by a stretching device. It is preferable to manufacture by stretching in the width direction.

The stretching operation may be performed in multiple stages. When biaxial stretching is carried out, simultaneous biaxial stretching may be carried out or may be carried out stepwise. In this case, stepwise means, for example, it is possible to sequentially perform stretching in different stretching directions, to divide stretching in the same direction into multiple stages, and to add stretching in different directions to any of the stages. Is also possible.

Thus, for example, the following stretching steps are possible:
Stretching in the longitudinal direction → Stretching in the width direction → Stretching in the longitudinal direction → Stretching in the longitudinal direction ・Stretching in the lateral direction → Stretching in the lateral direction → Stretching in the longitudinal direction → Stretching in the longitudinal direction ・Stretching in the lateral direction → Stretching in an oblique direction Simultaneous biaxial stretching also includes the case where stretching is performed in one direction and the other is contracted by relaxing the tension.

The cycloolefin film of the present invention has a glass transition temperature of Tg in the longitudinal direction and/or the width direction, preferably in the width direction so that the film thickness after stretching is in a desired range. , (Tg+5° C.) to (Tg+50° C.) in the temperature range. When the film is stretched within the above temperature range, the retardation can be easily adjusted and the stretching stress can be reduced, so that the haze becomes low. Further, it is possible to obtain a cycloolefin-based film which suppresses the occurrence of breakage and is excellent in flatness and coloring property of the film itself. The stretching temperature is preferably in the range of (Tg+10° C.) to (Tg+40° C.).

The glass transition temperature Tg referred to here is a midpoint glass transition temperature (Tmg) measured according to JIS K7121 (1987) by measuring at a temperature rising rate of 20° C./min using a commercially available differential scanning calorimeter. Is. A specific method for measuring the glass transition temperature Tg of the cycloolefin film is measured using a differential scanning calorimeter DSC220 manufactured by Seiko Instruments Inc. according to JIS K7121 (1987).

The cycloolefin-based film of the present invention is preferably stretched at least in the width direction, at a stretching ratio within the range of 5 to 40% with respect to the original width, and further in the longitudinal direction and the width direction of the film, It is more preferable to perform stretching at a stretching ratio within the range of 5 to 40% with respect to the length before stretching. In particular, the stretching ratio is more preferably 10 to 30% of the length before stretching. Within the above range, not only a desired retardation value can be obtained, but also a film can be thinned, particularly when a retardation increasing agent is included. The stretching ratio in the present invention refers to the ratio (%) of the length or width of the film after stretching to the length or width of the film before stretching.

The method of stretching in the longitudinal direction is not particularly limited. For example, a method in which the peripheral speed difference is applied to a plurality of rolls and the roll peripheral speed difference between them is used to stretch in the longitudinal direction, both ends of the web are fixed with clips or pins, and the interval between the clips or pins is widened in the traveling direction. And a method of stretching in the longitudinal direction, or a method of simultaneously stretching in the longitudinal and lateral directions and stretching in both the longitudinal and lateral directions. Of course, these methods may be used in combination.

In order to stretch in the width direction, for example, the entire drying process or a part of the process disclosed in JP-A-62-46625 is held in the width direction with clips or pins at both width ends of the web. While drying (called a tenter method), among them, a tenter method using a clip and a pin tenter method using a pin are preferably used.

When stretching in the width direction, it is preferable to stretch the film in the width direction at a stretching rate of 250 to 500%/min from the viewpoint of improving the flatness of the film.

When the stretching speed is 250%/min or more, the flatness is improved, and the film can be processed at high speed, which is preferable from the viewpoint of production suitability, and when it is 500%/min or less, the film breaks. It is preferable because it can be processed without any treatment.

A preferable stretching speed is in the range of 300 to 400%/min, and it is effective when stretching at a low magnification. The stretching speed is defined by the following formula 1.

Formula 1 Stretching speed (%/min)=[(d ₁ /d ₂ )−1]×100(%)/t
(In Formula 1, d ₁ is the width dimension of the cycloolefin film of the present invention after stretching in the stretching direction, d ₂ is the width dimension of the cycloolefin film before stretching in the stretching direction, and t is This is the time (min) required for stretching.)
The cycloolefin film of the present invention can be made into an optical compensation film by containing a retardation increasing agent and imparting a desired retardation value by stretching.

The preferred retardation value for the VA liquid crystal display device is that the in-plane retardation value Ro at the measurement wavelength of 590 nm is in the range of 10 to 100 nm, and the retardation value Rt in the thickness direction is in the range of 100 to 400 nm. preferable.

In the case of the IPS type liquid crystal display device, it is preferable that the in-plane retardation value Ro at the measurement wavelength of 590 nm and the retardation value Rt in the thickness direction are 0≦Ro≦5 nm and −15 nm≦Rt≦15 nm, respectively.

The in-plane retardation value Ro and the retardation value Rt in the thickness direction are measured using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics Co., Ltd.) under an environment of 23° C. and 55% RH. It is possible to perform three-dimensional refractive index measurement at a wavelength of 590 nm and calculate from the obtained refractive indexes nx, ny, and nz.

Formula _{(i): Ro = (n} x -n y) × d (nm)
Formula _{(ii): Rt = {(} n x + n y) / 2-n z} × d (nm)
[In the formulas (i) and (ii), n _x represents the refractive index in the direction x in which the refractive index is maximum in the in-plane direction of the film. n _y represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the film. _nz represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film. ]
In the stretching step, holding/relaxation is usually performed after stretching. That is, in this step, it is preferable to perform a stretching step of stretching the film, a holding step of holding the film in a stretched state, and a relaxation step of relaxing in the stretching direction of the film in this order. In the holding step, the drawing at the drawing rate achieved in the drawing step is held at the drawing temperature in the drawing step. In the relaxation step, the stretching in the stretching step is held in the holding step, and then the tension for stretching is released to relax the stretching. The relaxation step may be performed at a temperature equal to or lower than the drawing temperature in the drawing step.

(3-3) Main Drying Step In the main drying step, the stretched film is heated and dried by the second drying device 36.

Above all, in the present invention, in order to adjust the amount of the organic solvent contained in the cycloolefin film of the present invention, it is preferable to appropriately adjust the conditions of the main drying step.

When the film is heated with hot air or the like, a means for preventing the mixing of the used hot air by installing a nozzle capable of exhausting the used hot air (air containing solvent or wet air) is also preferably used. The hot air temperature is more preferably in the range of 40 to 350°C. The drying time is preferably about 5 seconds to 60 minutes, more preferably 10 seconds to 30 minutes.

Further, the heating and drying means is not limited to hot air, and, for example, infrared rays, heating rollers, microwaves or the like can be used. From the viewpoint of simplicity, it is preferable to dry the film with hot air or the like while transporting the film with the transport rollers 37 arranged in a staggered manner. The drying temperature is more preferably in the range of 40 to 350° C. in consideration of the amount of residual solvent, the expansion/contraction rate in transportation and the like.

In the drying step, the film is preferably dried until the residual solvent amount is generally 0.5% by mass or less.

(4) Winding Step (4-1) Knurling It is preferable to provide a slitter to cut off the end after a predetermined heat treatment or cooling treatment before winding, in order to obtain a good winding shape. Furthermore, it is preferable to perform knurling on both widthwise ends.

The knurling process can be formed by pressing a heated embossing roller against the widthwise end of the film. Fine embossments are formed on the embossing roller, and by pressing this, embossments can be formed on the film and the edges can be made bulky.

The height of the knurling at both widthwise end portions of the cycloolefin film of the present invention is preferably 4 to 20 μm and the width is 5 to 20 mm.

Further, in the present invention, the above-mentioned knurling is preferably provided after the completion of drying in the film forming step and before the winding.

(4-2) Winding step This is a step of winding the film as a film after the residual solvent amount in the film becomes 2% by mass or less, and the dimensional stability is preferably set to 0.4% by mass or less. It is possible to obtain a good film.

As a winding method, a generally used one may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like, and these may be used properly.

(4-3) Protect Film The cycloolefin-based film of the present invention is preferably wound in a roll while further bonding the protect film on the surface of the cycloolefin-based film. The protect film is used for the purpose of preventing damage such as scratches during storage or transportation of the optical film, or during handling such as polarizing plate processing.

The material of the film used as the protect film is not particularly limited, and examples thereof include a cellulose ester film, a polyester film, a polycarbonate film, a polyarylate film, a polysulfone (including polyether sulfone) film, and a polyethylene film. Polyolefin film such as polypropylene film, cellophane, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, norbornene resin film, polymethylpentene film, polyetherketone film, polyetherketone Examples thereof include imide film, polyamide film, fluororesin film, nylon film, polymethylmethacrylate film and acrylic film. Among them, polyethylene film and polypropylene film are preferable from the viewpoint of film physical properties and cost.

The thickness of the protect film used in the present invention is preferably 10 to 100 μm, more preferably 15 to 50 μm. If the protect film is less than 10 μm, the ability to protect the optical film will be poor, and wrinkles will tend to occur during winding, and if it exceeds 100 μm, the roll of the optical film roll will become large and the weight will increase, so it will be stored. In some cases, handling may be hindered during transportation.

In addition, the protect film may have an adhesive layer, and the adhesive layer includes those that form an adhesive layer by coating and those that form a self-adhesive layer by co-extrusion. From the viewpoint that it can be spread, a method of forming an adhesive layer by coating is preferable.

Examples of the adhesive include rubber-based adhesives, acrylic-based adhesives, polyvinyl ether-based adhesives, urethane-based adhesives, and silicone-based adhesives. Among these adhesives, one kind may be used alone, or two or more kinds may be used in combination at an arbitrary ratio. Among them, an acrylic adhesive is preferable from the viewpoint of heat resistance and productivity.

The thickness of the adhesive layer is preferably in the range of 2 to 20 μm, more preferably 5 to 15 μm. When the thickness of the adhesive layer is thicker than 20 μm, a problem that adhesive residue is likely to occur when it is bonded to an optical film and peeled off, the feeding tension of the protect film becomes high, and wrinkles and scratches are caused at the time of bonding with the optical film. It is likely to occur. On the other hand, if the thickness is less than 2 μm, the adhesive force may be low and the protective film may be lifted or peeled off.

The protect film may be manufactured with a configuration in which a separator is used on the adhesive layer surface for the purpose of preventing foreign matter from entering and suppressing winding wrinkles. In that case, in order to reduce the peeling force between the pressure-sensitive adhesive layer surface and the separator and to suppress peeling electrification, it is common to subject the separator to a mold release treatment. As the release agent, silicone-based materials such as polydimethylsiloxane, fluorine-based materials such as alkyl fluoride, and long-chain alkyl are used. Among them, silicone-based materials are preferably used because they have good mold releasability and processability.

[4] Physical Properties of Cycloolefin Film <Haze>
The cycloolefin film of the present invention preferably has a haze of less than 1%, more preferably less than 0.5%. By setting the haze to less than 1%, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as a film for optical use.

The haze value is measured at 10 points at equal intervals in the width direction of the film with a haze meter (NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.) under an environment of 23° C. and 50% RH, and the average value is calculated. I asked for haze.

<Equilibrium water content>
The cycloolefin film of the present invention preferably has an equilibrium water content of 4% or less at 25° C. and a relative humidity of 60%, more preferably 3% or less. By setting the equilibrium water content to 4% or less, it is easy to respond to changes in humidity, and it is more difficult for optical characteristics and dimensions to change, which is preferable.

The equilibrium water content is determined by leaving the sample film in a room conditioned at 23° C. and a relative humidity of 20% for 4 hours or more, and then in a room conditioned at 23° C. 80% RH for 24 hours. Using a meter (for example, CA-20 type manufactured by Mitsubishi Chemical Analytech Co., Ltd.), water is dried and vaporized at a temperature of 150° C., and then quantified by the Karl Fischer method.

<Film length, width, film thickness>
The cycloolefin-based film of the present invention is preferably long, specifically, about 100 to 10,000 m long and wound into a roll. The width of the cycloolefin film of the present invention is preferably 1 m or more, more preferably 1.3 m or more, and particularly preferably 1.3 to 4 m.

The film thickness of the film after stretching is in the range of 5 to 40 μm from the viewpoint of thinning the display device and productivity. When the film thickness is 5 μm or more, it is possible to exhibit a film strength or retardation of a certain level or more. When the film thickness is 40 μm or less, it is easy to provide the film with a desired retardation, and it can be applied to thinning the polarizing plate and the display device. The preferred film thickness is in the range of 15-35 μm. When the film thickness exceeds 40 μm, it becomes difficult to reduce the thickness and weight of the display device.

[5] Application of Optical Film The optical film of the present invention is preferably a functional film used for various display devices such as liquid crystal display devices and organic EL display devices and touch panels. Specifically, the optical film of the present invention is a polarizing plate protective film for a liquid crystal display device or an organic EL display device, a retardation film (also referred to as an optical compensation film) for expanding a viewing angle, an antireflection film, and a brightness enhancement. It may be a film, a hard coat film, an antiglare film, an antistatic film or the like. Typically, the optical film of the present invention is a polarizing plate protective film. The optical film of the present invention can also be used as a polarizing plate protective film that doubles as the retardation film. Since the optical film of the present invention is excellent in scratch resistance and handleability, it is an optical film which is also excellent in processability after the protective film is peeled off.

[5.1] Polarizing Plate [5.1.1] Polarizer A polarizer is an element that allows only light having a polarization plane in a certain direction to pass therethrough, and examples thereof include a polyvinyl alcohol-based polarizing film.

The polyvinyl alcohol-based polarizing film includes a polyvinyl alcohol-based film dyed with iodine and a polyvinyl alcohol-based film dyed with a dichroic dye.

The polarizer can be obtained by uniaxially stretching a polyvinyl alcohol film, followed by dyeing, or after dyeing a polyvinyl alcohol film, then uniaxially stretching, and preferably further subjected to a durability treatment with a boron compound.

The film thickness of the polarizer is preferably in the range of 5 to 30 μm, and more preferably in the range of 5 to 15 μm.

As the polyvinyl alcohol film, the content of ethylene units described in JP-A-2003-248123 and JP-A-2003-342322 is 1 to 4 mol %, the degree of polymerization is 2000 to 4000, and the degree of saponification is 99.0 to 99. Ethylene-modified polyvinyl alcohol of .99 mol% is preferably used. In addition, it is preferable to prepare a polarizer by the method described in JP 2011-100161 A, JP 4691205 A, JP 4804589 A, and to bond it to the optical film of the present invention to prepare a polarizing plate.

[5.1.2] Adhesive [Water glue]
In the polarizing plate used in the present invention, it is preferable that the optical film of the present invention is attached to a polarizer using a completely saponified polyvinyl alcohol aqueous solution (water glue). Another polarizing plate protective film can be attached to the other surface. When the optical film of the present invention is used as a liquid crystal display device, it is preferably provided on the liquid crystal cell side of the polarizer, and the film outside the polarizer is the optical film of the present invention and a conventional polarizing plate protective film. Either can be used.

For example, the conventional polarizing plate protective film, commercially available cellulose ester film (for example, Konica Minolta TAC KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC6UA, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC8UX- RHA, KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, and above Konica Minolta Co., Ltd. product are used preferably.

[Active energy ray curable adhesive]
In addition, in the polarizing plate used in the present invention, it is preferable that the optical film of the present invention and the polarizer are bonded together by an active energy ray-curable adhesive.

As the active energy ray curable adhesive, it is preferable to use the ultraviolet curable adhesive described below.

In the present invention, by applying an ultraviolet-curable adhesive to bond the optical film and the polarizer, it is possible to obtain a polarizing plate having high strength and excellent flatness even with a thin film.

<Composition of UV curable adhesive>
As the ultraviolet curable adhesive composition for a polarizing plate, a photoradical polymerization type composition utilizing photoradical polymerization, a photocationic polymerization type composition utilizing photocationic polymerization, and a combination of photoradical polymerization and photocationic polymerization Hybrid type compositions are known.

The radical photopolymerizable composition contains a radical polymerizable compound containing a polar group such as a hydroxy group or a carboxy group and a radical polymerizable compound containing no polar group described in JP-A-2008-009329 in a specific ratio. Composition) and the like are known. In particular, the radically polymerizable compound is preferably a compound having a radically polymerizable ethylenically unsaturated bond. A preferable example of the compound having a radically polymerizable ethylenically unsaturated bond includes a compound having a (meth)acryloyl group. Examples of the compound having a (meth)acryloyl group include N-substituted (meth)acrylamide compounds and (meth)acrylate compounds. (Meth)acrylamide means acrylamide or methacrylamide.

Further, as the cationic photopolymerization type composition, (α) cationically polymerizable compound, (β) photocationic polymerization initiator, and (γ) wavelength longer than 380 nm as disclosed in JP 2011-028234A. An ultraviolet-curable adhesive composition containing each component of a photosensitizer that exhibits maximum absorption for the above light and (δ) a naphthalene-based photosensitization aid. However, other UV curable adhesives may be used.

(1) Pretreatment Step The pretreatment step is a step of subjecting the adhesive surface of the optical film to the polarizer to an easy adhesion treatment. Examples of the easy adhesion treatment include corona treatment and plasma treatment.

(Application process of UV curable adhesive)
In the step of applying the ultraviolet curable adhesive, the ultraviolet curable adhesive is applied to at least one of the bonding surfaces of the polarizer and the optical film. When the ultraviolet curable adhesive is directly applied to the surface of the polarizer or the optical film, the application method is not particularly limited. For example, various wet coating methods such as doctor blade, wire bar, die coater, comma coater and gravure coater can be used. Alternatively, a method in which an ultraviolet-curable adhesive is cast between the polarizer and the optical film and then pressed by a roller or the like to uniformly spread it can be used.

(2) Bonding Step After applying the ultraviolet curable adhesive by the above method, the bonding step is performed. In this bonding step, for example, when the surface of the polarizer is coated with the ultraviolet curable adhesive in the previous coating step, the optical film is superposed thereon. Further, in the case of a system in which an ultraviolet curable adhesive is first applied to the surface of the optical film, a polarizer is superposed thereon. Further, when the ultraviolet curable adhesive is cast between the polarizer and the optical film, the polarizer and the optical film are superposed in that state. Then, in this state, the pressure is normally applied by sandwiching the optical films on both sides with a pressure roller or the like. As the material of the pressure roller, metal, rubber or the like can be used. The pressure rollers arranged on both sides may be made of the same material or different materials.

(3) Curing Step In the curing step, the uncured ultraviolet curable adhesive is irradiated with ultraviolet rays to generate a cationically polymerizable compound (eg, epoxy compound or oxetane compound) or a radically polymerizable compound (eg, acrylate compound, acrylamide). The ultraviolet curable adhesive layer containing a compound or the like) is cured, and the laminated polarizer and the optical film are adhered via the ultraviolet curable adhesive. When the optical film is attached to one surface of the polarizer, the active energy ray may be irradiated from either the polarizer side or the optical film side. Further, when the optical films are attached to both sides of the polarizer, the optical films are superposed on both sides of the polarizer via the ultraviolet curable adhesives, respectively, and the ultraviolet rays are irradiated to the ultraviolet curable adhesives on both sides. It is advantageous to cure the two simultaneously.

Any appropriate condition can be adopted as the irradiation condition of the ultraviolet light as long as it can cure the ultraviolet curable adhesive applied to the present invention. Preferably the dose of ultraviolet rays in the range of 50~1500mJ / cm ² in accumulated light quantity, and even more preferably in the range of 100 to 500 mJ / cm ^2.

When the production process of the polarizing plate is performed in a continuous line, the line speed depends on the curing time of the adhesive, but is preferably in the range of 1 to 500 m/min, more preferably 5 to 300 m/min, and further preferably 10 It is in the range of 100 m/min. When the line speed is 1 m/min or more, productivity can be secured, or damage to the optical film can be suppressed, and a polarizing plate excellent in durability can be manufactured. If the line speed is 500 m/min or less, the ultraviolet curable adhesive will be sufficiently cured, and the ultraviolet curable adhesive layer having the desired hardness and excellent adhesiveness can be formed.

[5.1.3] Protective Film The film disposed on the side of the polarizer opposite to the optical film of the present invention is preferably a film that functions as a protective film for the polarizer.

As such a protective film, the optical film of the present invention may be used. For example, a commercially available cellulose ester film (for example, Konica Minolta Tuck KC8UX, KC5UX, KC4UX, KC8UCR3, KC4SR, KC4BR, KC4CR, KC4DR, KC4FR). , KC4KR, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC2UA, KC4UA, KC6UAKC, 2UAA, KC4UAH, KT4UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, UZT, TZU, TZU, TZUU, TZUU, TZUU, TJUU, TJUZU, TJUU, TJUU, TUCHIZU, TJUU, TJUU, TUCHIU, KC4UU, TUCHIZU, TJUU, TUCHIUU TD60UL, FUJI TAC TD40UL, FUJI TAC R02, FUJI TAC R06, manufactured by Fuji Film Co., Ltd. can also be preferably used.

Further, for example, resin films such as polyethylene terephthalate, polyethylene naphthalate, and polycarbonate, alicyclic polyolefins (for example, Zeonor (registered trademark) manufactured by Nippon Zeon Co., Ltd., polyarylate, polyether sulfone, polysulfone, cycloolefin copolymer, polyimide) (For example, Neoprim (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Inc.), resin films such as fluorene ring-modified polycarbonate, alicyclic-modified polycarbonate, and acryloyl compound are included (the glass transition temperature Tg is shown in parentheses). Among the resin base materials, polyethylene terephthalate (abbreviation: PET), polybutylene terephthalate, polyethylene naphthalate (abbreviation: PEN), polycarbonate (abbreviation: PC), etc. are used as protective films in terms of cost and availability. It is preferably used.

The thickness of the protective film is not particularly limited, but may be about 10 to 200 μm, preferably within the range of 10 to 100 μm, and more preferably within the range of 10 to 70 μm.

[5.2] Liquid crystal display device By using the polarizing plate to which the optical film of the present invention is attached in a liquid crystal display device, various liquid crystal display devices used in the present invention having excellent visibility can be manufactured. ..

Further, since the optical film of the present invention contains silica particles in the film, it can be used as a polarizing plate for display applications having a polygonal shape or a curved line. It is also possible to solve the conventional problems that cracks such as crimps and cracks are generated, and chips due to cutting are easily generated.

The polarizing plate used in the present invention can be used in liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, and OCB. Preferred are a VA (MVA, PVA) type liquid crystal display device and an IPS type liquid crystal display device.

A liquid crystal display device usually uses two polarizing plates, a polarizing plate on the viewing side and a polarizing plate on the backlight side, but it is also preferable to use the polarizing plates used in the present invention as both polarizing plates. It is also preferable to use it as a polarizing plate. In particular, the polarizing plate used in the present invention is preferably used as a polarizing plate on the viewing side that directly contacts the external environment. When the optical film of the present invention is a protective film, the viewing side surface or the optical film of the present invention is optically compensated. In the case of a film, it is preferably arranged on the liquid crystal cell side. When used as an optical compensation film of an IPS type liquid crystal display device, it is preferably arranged on both sides of a liquid crystal cell.

Further, as the polarizing plate on the backlight side, polarizing plates other than those of the present invention can be used, and in that case, a polarizing plate in which the above-mentioned protective films are laminated on both surfaces of the polarizer is preferably used.

Further, as the polarizing plate on the backlight side, the optical film of the present invention is used on the liquid crystal cell side of the polarizer, and the commercially available protective film or retardation film, polyester film, acrylic film, polycarbonate film, or on the opposite surface. A polarizing plate laminated with another cycloolefin film can also be preferably used.

By using the polarizing plate used in the present invention, it is possible to obtain a liquid crystal display device having excellent visibility such as display unevenness and front contrast even in the case of a large screen liquid crystal display device having a screen size of 30 inches or more.

[5.3] Organic electroluminescence display device The optical film using the cycloolefin resin of the present invention has good slidability and thus has high processability, and is suitable for, for example, an organic electroluminescence display device having a curved shape. is there.

Regarding the outline of the organic EL element applicable to the organic electroluminescence display device used in the present invention, for example, JP 2013-157634 A, JP 2013-168552 A, JP 2013-177361 A, JP JP-A 2013-187221, JP-A 2013-191644, JP-A 2013-191804, JP-A 2013-225678, JP-A 2013-235994, JP-A 2013-243234, JP-A 2013-2013. No. 243236, JP2013-242366A, JP2013-243371A, JP2013-245179A, JP2014-003249A, JP2014-003299A, JP2014-013910A. The configurations described in the publications, JP-A-2014-017493, JP-A-2014-017494 and the like can be mentioned.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, “parts” or “%” is used, but unless otherwise specified, “parts by mass” or “% by mass” is indicated.

Example 1
<Silica particles with surface modification used in Examples: Surface modifier>
Below, manufactured by Nippon Aerosil Co., Ltd. (trade name) Aerosil series R972: dimethylsilane R812: trimethylsilane R805: octylsilane R816: hexadecylsilane NKC130: dimethylsiloxane R711: methacryloxysilane RY300: dimethylsiloxane R104: dimethylsiloxane cyclic RA200H. : Aminosilane <Production of Optical Film 101>
(Synthesis of cycloolefin resin P)
8-Methyl-8-methoxycarbonyltetracyclo[4.4.0.12,5. 75% by mass of 17,10]-3-dodecene (DNM), 24% by mass of dicyclopentadiene (DCP), 1% by mass of 2-norbornene, 9 parts of 1-hexene as a molecular weight regulator and 200 parts of toluene were replaced with nitrogen. The reaction vessel was charged and heated to 110°C. To this, 0.005 parts of triethylaluminum and 0.005 parts of methanol-modified WCl6 (anhydrous methanol:PhPOCl2:WCl6=103:630:427 mass ratio) were added and reacted for 1 hour to obtain a polymer. The obtained polymer solution was placed in an autoclave, and 200 parts of toluene was further added. Next, 0.006 parts of RuHCl(CO)[P(C ₆ H ₅ )] ₃ , which is a hydrogenation catalyst, was added, and after heating to 90° C., hydrogen gas was charged into the reactor, and the pressure was adjusted to 10 MPa. did. Then, the reaction was carried out at 165° C. for 3 hours while maintaining the pressure at 10 MPa. After completion of the reaction, a large amount of a methanol solution was precipitated, and the precipitate was reprecipitated and purified using toluene and methanol to obtain a copolymer P.

The copolymer P has a weight average molecular weight (Mw) of 7.2×10 ⁴ , a molecular weight distribution (Mw/Mn) of 3.3, and a glass transition temperature (Tg) of 143 measured by gel permeation chromatography (GPC). It was ℃. The addition rate of the methoxycarbonyl group of the copolymer P was determined by ¹³ CNMR measurement, and it was confirmed that 75% by mass of the monomer having a methoxycarbonyl group was added. The copolymer P obtained above is a cycloolefin resin P having 75% by mass of a monomer having a methoxycarbonyl group as a hydrogen bond accepting group.

(Preparation of fine particle dispersion)
Silica fine particles (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.)
11 mass%
89% by mass of dichloromethane
After stirring and mixing the above with a dissolver for 50 minutes, dispersion was carried out using a Manton-Gorlin disperser to prepare a fine particle dispersion.
(Preparation of fine particle additive liquid 1)
Dichloromethane was placed in a dissolution tank, and the above-prepared fine particle dispersion was slowly added to 50% by mass while sufficiently stirring the dichloromethane. Further, the secondary particles were dispersed with an attritor so that the particle diameter became a predetermined size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive liquid 1.

(Preparation of dope)
The cycloolefin resin P synthesized above was put into a pressure dissolution tank containing ethanol while stirring. Next, the fine particle additive liquid was added so as to have the addition amount shown in Table 1, and then heated at the dissolution temperature shown in Table 1 for 3 hours and completely dissolved while stirring. After that, Azumi Filter Paper No. manufactured by Azumi Filter Paper Co., Ltd. The dope was prepared by filtration using 244. The composition of the dope is shown below.

Cycloolefin resin P 100.0% by mass
Dichloromethane 290.0% by mass
Fine-particle-added liquid added in an amount of 0.30% by mass in the film Using a band casting apparatus, the prepared dope was cast on a stainless casting support (support temperature 22° C.). The dope is peeled off in a state where the residual solvent amount is about 20% by mass, and both ends in the width direction of the film are held by tenters, and when the residual solvent amount is 10% by mass, the width direction is 1 at a temperature of 125°C. It was dried while being stretched 0.01 times (1%). After that, it is further dried by conveying it between rolls of a heat treatment device at 90° C. for 30 minutes, and then a commercially available polyethylene protective film (R7832C manufactured by Toray Processing Film Co., film thickness 30 μm, abbreviated as PE) is attached. The optical film 101 was manufactured by winding the film at a speed of 20 m/sec. The optical film (indicated as COP film in the table) had a thickness of 15 μm, a width of 1492 mm, and a length of 4000 m.

<Production of optical film 102>
In the production of the optical film 101, an optical film 102 was produced in the same manner except that the optical film was wound up without using the protect film.

<Production of optical film 103>
An optical film 103 was produced in the same manner as in the production of the optical film 101 except that R812 was used instead of the silica particles R972.

<Production of optical film 104>
An optical film 104 was produced in the same manner as in the production of the optical film 103, except that the optical film was wound up without using the protect film.

<Production of optical film 105>
An optical film 105 was produced in the same manner as in the production of the optical film 101 except that RY300 was used instead of the silica particles R972.

<Production of optical film 106>
In the production of the optical film 105, an optical film 106 was produced in the same manner except that the optical film was wound up without using the protect film.

<Production of optical film 107>
An optical film 107 was produced in the same manner as in the production of the optical film 101 except that NKC130 was used instead of the silica particles R972.

<Production of optical film 108>
An optical film 108 was produced in the same manner as in the production of the optical film 107, except that the optical film was wound up without using the protect film.

<Production of optical films 109 to 114>
In the production of the optical film 107, the film thickness after drying was changed to 3 μm, 5 μm, 10 μm, 15 μm, 30 μm, 40 μm by changing the film thickness of the COP film on the casting support. Except for this, optical films 109 to 114 were produced in the same manner.

<Production of optical films 115 to 121>
In the production of the optical film 107, the thickness of the COP film is set to 20 μm, and the addition amount of silica particles is 0.05% by mass, 0.10% by mass, 0.30% by mass, 0.50% by mass, 1.00. Optical films 115 to 121 were produced in the same manner except that the contents were changed to 100% by mass, 5.00% by mass, and 6.00% by mass.

<Production of optical films 122 to 126>
In the production of the optical film 118, optical films 122 to 126 were produced in the same manner except that the silica particles NKC130 were replaced with R805, R816, R711, R104, and RA200H.

The following evaluation was implemented using the optical films 101-126 produced above.

<<Evaluation>>
[1] Methanol wettability evaluation (indicated as MW method in the table)
In a mixed solution of methanol and pure water, while changing the mixing ratio of methanol to pure water, the same amount (the same volume) of silica particles was added to each solution and mixed by stirring, and each mixed solution was centrifuged. Separated, the volume of the sediment of the silica particles was obtained, and the methanol mixing ratio of the solution in which the volume of the silica particle sediment was 50% was shown.

When the mixing ratio of methanol is 50% by volume or more, the silica particles are judged to meet the object of the present invention.

R972: Dimethylsilane: Methanol 42% by volume
R812: trimethylsilane: methanol 48% by volume
R805: Octylsilane: Methanol 50% by volume
R816: Hexadecylsilane: Methanol 54% by volume
NKC130: Dimethylsiloxane: Methanol 67% by volume
R711: Methacryloxysilane: Methanol 55% by volume
RY300: dimethylsiloxane: methanol 69% by volume
R104: dimethylsiloxane cyclic compound: 60% by volume of methanol
RA200H: Aminosilane: Methanol 51% by volume
[2] Particle size of silica particles in the film The particle size of the silica particles in the optical film is measured by taking a cross section of the film cut by a microtome with a scanning electron microscope (SEM) at an appropriate magnification. Then, the particle diameter of 100 particles included in the tomographic cut photograph was measured, and the average value was calculated and used as the average particle diameter. The particle diameter was the diameter when the cross section of the particle was circular, and the diameter when it was converted to a circular shape by calculating the area when it was not circular.

SEM: JSM-6060LA (JEOL: JEOL Ltd.)
Microtome: Leica EM UC6
[3] Evaluation of Transfer (Fish Eye) and Scratch Resistance The presence or absence of transfer (fish eye) and generation of scratch (scratch resistance) by the protect film was visually evaluated by unwinding the wound optical film.

The surface of the optical film opposite to the protective film is irradiated with light using a sodium lamp (KNL-35D, manufactured by Lytest Co., Ltd.) and a three-wavelength fluorescent lamp, and unevenness and scratches n on the surface of the optical film are generated in a dark room Was evaluated. The evaluated site is the surface inside of that excluding the end 5 cm.

⊚: No transfer or scratch generation ○: Either transfer or scratch generation is slight △: Both transfer and scratch generation are slight ×: Both transfer and scratch generation are obvious Practical Specifically, the grade Δ or higher is acceptable, but the grade is preferably ○ to ◎.
Table 1 shows the configuration of the optical film and the evaluation results.

From Table 1, the cycloolefin-based film containing the silica particles according to the present invention is excellent in transfer/scratch generation even without a protective film, and when the protective film is laminated and wound up, transfer failure/scratch generation failure is further caused. It turns out to be excellent.

The optical film 121 containing silica particles in an amount of 6.00 mass% is excellent in transfer failure and scratch generation failure, but has a slightly high haze and a slightly low quality as an optical film.

Example 2
<Production of optical films 201 to 206>
In the production of the optical film 111, optical films 201 to 206 were produced in the same manner except that the material and film thickness of the protect film were changed as shown in Table 2.

Polyethylene film (indicated as PE in the table): R7832C manufactured by Toray Processing Film Co., Ltd., film thickness 30 μm, 50 μm
Polypropylene film (denoted as PP in the table): PR series manufactured by San-A Kaken Co., Ltd., film thickness 30 μm, 50 μm
Polyester film (indicated as PET in the table): polyethylene terephthalate film manufactured by Toray Industries, Inc. Lumirror (registered trademark) (U403), film thickness 30 μm, 50 μm
Using the optical films 201 to 206 produced above, the same transfer and scratch generation evaluation as in Example 1 were performed, and the results are shown in Table 2.

From the results in Table 2, it can be seen that by adjusting the film thickness of the protect film, the transfer/scratch resistance similar to that of the relatively expensive polyester film can be achieved with the inexpensive polyethylene film or polypropylene film.

Example 3
<Production of optical films 301 to 306>
The same as in the production of the optical film 107, except that the winding speed was changed to 5 m/sec, 10 m/sec, 20 m/sec, 30 m/sec, 40 m/sec, 50 m/sec while sticking the protective film. Then, the optical films 301 to 306 were produced.

<Production of optical films 307 to 312>
In the production of the optical film 108, the optical films 307 to 312 were similarly prepared except that the winding speed was changed to 5 m/sec, 10 m/sec, 20 m/sec, 30 m/sec, 40 m/sec, and 50 m/sec. Was produced.

Using the optical films 301 to 312 manufactured as described above, transfer and scratch generation evaluation were performed in the same manner as in Example 1, and the results are shown in Table 3.

From the results of Table 3, the cycloolefin-based film containing the silica particles according to the present invention, when the protective film was laminated and wound up, the transfer failure and the scratches were generated even if the production rate was significantly increased. It can be seen that it is excellent in failure and can contribute to productivity improvement.

Further, the optical film of the present invention is excellent in scratch resistance even without a protect film, but the scratch resistance tends to be inferior as the production speed is increased.

The optical film of the present invention, even if it is a thin optical film containing a cycloolefin resin as a main component, when forming an optical film roll body with an inexpensive protect film, transfer failure and scratch failure hardly occur, It is also suitable for use in a polarizing plate or a liquid crystal display device because it is excellent in processability after peeling off the protective film.

DESCRIPTION OF SYMBOLS 1 Melting kettle 3, 6, 12, 15 Filtration machine 4, 13 Stock kettle 2, 5, 11, 14 Liquid feed pump 8, 16 Conduit 10 Additive charging kettle 20 Combiner pipe 21 Mixer 30 Pressing die 31 Metal support 32 Web 33 Peeling Position 34 Stretching Device 35 Drying Device 36 Conveying Roller 37 Winding Device 38 Protect Film Roll 41 Charging Pot 42 Stock Pot 43 Pump

Claims (4)

An optical film containing a cycloolefin resin as a main component and having a film thickness in the range of 5 to 40 μm, which is an alkylsilane having an alkyl group having 5 to 21 carbon atoms, dimethylsiloxane, a dimethylsiloxane cyclic body, and methacrylic acid. Roxysilane, and silica particles surface-modified with at least one compound selected from aminosilane are contained in the range of 0.1 to 5.0 mass% with respect to the total mass of the film. Optical film to do. The optical film according to claim 1, wherein the average particle size of the silica particles in the film is in the range of 5 to 400 nm. An optical film roll body, comprising a protective film provided on the surface of the optical film according to claim 1 or 2 . It is a manufacturing method of the optical film which manufactures the optical film of Claim 1 or Claim 2, Comprising: The said optical film is manufactured by the solution casting film forming method, The manufacturing method of the optical film characterized by the above-mentioned.

Images