KR20150043480A - Optical film - Google Patents

Abstract

In the optical film F in which the cured film 2 is formed on the film substrate 1 having a thickness of 10 to 40 占 퐉, the respective regions from the both end portions in the width direction of the film substrate 1 to 50 mm, Is referred to as a region R1 and a second region R2. The cured film 2 is formed on the film base 1 in a range of 20 to 100% in the width direction in the first region R1 and in a range of 20 to 100% in the width direction in the second region R2 Respectively. The knurl portion 3 is formed by knurling the surface of the cured film 2 in each of the first region R1 and the second region R2 after the cured film is formed. The nulling portions 3 are formed on the surface of the cured film 2 in a width direction of 3 mm or more from each end of the cured film 2.

Description

Optical film {OPTICAL FILM}

The present invention relates to an optical film on which a cured film is formed on a film substrate having a small film thickness.

In recent years, various display devices such as a liquid crystal TV, a plasma display, and an organic EL (Electro Luminescence) display have been developed in addition to a CRT (Cathode Ray Tube), and their screen sizes are becoming larger. In such a display device, there is a case in which a hand touches the screen directly or an object touches the screen, and the screen is liable to be scratched. Therefore, in order to prevent scratches, an optical film on which a hard coating layer (cured film) is formed on a film substrate or an optical film on which an antireflection layer or the like is formed on a hard coating layer is attached to a display screen of a display device Work is being done.

In the production of such an optical film, a film substrate provided with a bulging portion or a portion (convex portion) higher in bulky density than the film surface is used at both end portions in the width direction. By forming the knurled portion on the film base, displacement of the film base in the winding core direction and blocking (adherence) between the base materials can be suppressed when the produced film base is wound around the winding core. By forming a hard coat layer on the surface of such a film substrate, an optical film having a hard coat layer can be obtained. The obtained optical film is wound around a winding core again.

For example, in Patent Documents 1 and 2, a hard coat layer is formed on a film substrate so that the knurled portion of the film substrate is located outside the hard coat layer, Further, another knurling portion is additionally formed on the knurled portion of the substrate. In this case, since the additional knurled portion can be formed by using the unevenness of the knurled portion formed earlier, the knurled portion of the desired height can be easily formed with high accuracy without significantly increasing the thickness of the uneven portion of the embossed roll. Further, for example, in Patent Document 3, a hard coating layer is applied to a knurled portion of a film base, and a fine protrusion is formed on the back surface of the knurled portion to produce an optical film.

However, in recent years, along with the thinness of the display device, the thickness of the optical film to be used has also been required. Here, when the produced optical film is wound on the winding core and the winding diameter is constant, when the thin optical film is wound, the number of windings can be increased compared with the case of winding the optical film having a large thickness have. As a result, it becomes possible to produce an optical film having a long shape (for example, 3000 m or more) having a large number of windings as a thin optical film.

However, in Patent Documents 1 and 2, since the knurled portion is formed on the soft film base material rather than the hard coat layer, the knurled portion tends to be distorted by the self weight or pressing force when the long optical film is wound. If the knurled portion is squashed, winding displacement and blocking of the optical film can not be suppressed. In Patent Document 3, the fine protrusions on the back surface of the knurled portion can be considered to be protrusions provided on the back surface of the film base which forms the base of the hard coating layer. However, since these protrusions are softer than the hard coating layer, The projections are liable to be distorted when the film is wound, so that it is impossible to suppress winding displacement or the like.

Therefore, even when a thin optical film having a thin film thickness is to be wound, it is desired to construct an optical film so as to reliably suppress winding displacement and blocking.

Japanese Patent Application Laid-Open No. 2005-219272 (see claim 1, paragraph [0028], Fig. 1, etc.) Japanese Patent Laid-Open Publication No. 2009-223129 (paragraph [0026], Fig. 1, etc.) Japanese Patent Application Laid-Open No. 2004-347928 (see claim 4, paragraph [0015], etc.)

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical film which can reliably suppress winding deviation and blocking even when a thin optical film having a thin film thickness is wound in view of the above circumstances.

The above object of the present invention is achieved by the following constitution.

1. An optical film on which a cured film is formed on a film substrate having a thickness of 10 to 40 占 퐉,

When the respective regions from the both end portions in the width direction of the film base material to 50 mm are referred to as a first region and a second region,

The cured film is formed so as to cover 20 to 100% in the width direction in the first region and 20 to 100% in the width direction in the second region on the film substrate,

A knurled portion of a concavo-convex shape is formed on the surface of the cured film in each of the first region and the second region by knurling after forming the cured film,

Wherein the knurling portion is formed on the surface of the cured film in a range of 3 mm or more in the width direction from each end of the cured film.

2. The optical film as described in 1 above, wherein the knurling portion has a height of 1 to 25 占 퐉.

3. The optical film according to 1 or 2, wherein the number of convex portions of the knurled portion is 10 to 140 per cm ² .

4. The optical film according to any one of 1 to 3 above, wherein the cured film has a modulus of elasticity of 4.0 GPa or more.

According to the above configuration, the knurled portion of the concavo-convex shape is formed by knurling the surface of the cured film on the thin film substrate having a thickness of 10 to 40 占 퐉 after the cured film is formed. Since the knurled portion has a hardness of the cured film, not only the unevenness formed on the film substrate, but also the optical film is hardly distorted by its own weight or pressing force. As a result, even when the thin and long optical film is wound, winding displacement and blocking in the direction of the winding core can be suppressed.

In addition, since the knurled portion is formed over 3 mm or more from the end portion in the width direction of the film substrate, the resistance against the width direction (winding core direction) can surely be increased and also the strength of the knurled portion can be assured . As a result, winding displacement and blocking in the winding core direction at the time of winding the thin optical film can be reliably suppressed.

Further, since the cured film is formed so as to cover the range of 20 to 100% in the width direction in the first region and the second region (an area up to 50 mm from each end in the width direction) on the film substrate, The range of formation of the cured film in the second region is 10 mm (corresponding to 20% of 50 mm) to 50 mm (corresponding to 100% of 50 mm) in the width direction. Therefore, it is possible to reliably secure a formation width of the knurled portion of 3 mm or more on the surface of the cured film of the first region and the second region.

1 is a cross-sectional view showing a schematic structure of an optical film according to an embodiment of the present invention.
2 is a cross-sectional view showing another structure of the optical film.
Fig. 3 is an enlarged cross-sectional view of the cured film of the optical film of Figs. 1 and 2. Fig.
Fig. 4 is a cross-sectional view showing a schematic structure of the optical film of Example 1. Fig.
5 is a cross-sectional view showing a schematic structure of the optical film of Example 10. Fig.
6 is a cross-sectional view showing a schematic structure of the optical film of Example 11. Fig.
7 is a cross-sectional view showing a schematic structure of the optical film of Example 12. Fig.
8 is a cross-sectional view showing a schematic structure of the optical film of Example 13. Fig.
9 is a cross-sectional view showing a schematic structure of an optical film of Comparative Example 2. Fig.

An embodiment of the present invention will be described below with reference to the drawings. In the present specification, when the numerical ranges are denoted by A to B, the lower limit (A) and the upper limit (B) are included in the numerical range.

[Composition of optical film]

1 is a cross-sectional view along the width direction showing a schematic structure of an optical film F of the present embodiment. Further, the width direction refers to a direction (TD direction; Transverse Direction) perpendicular to the longitudinal direction (machine direction) in the film plane. The optical film (F) is a hard coating film on which a cured film (2) as a hard coating layer is formed on a film substrate (1). The film substrate 1 has a thickness of 10 to 40 占 퐉 and is a substrate of a thin film. Here, for convenience of explanation, each region from the both end portions in the width direction of the film base 1 to 50 mm is referred to as a first region R1 and a second region R2.

The cured film 2 is made of, for example, an active energy ray curable resin such as an ultraviolet curable resin. Details of the resin material of the cured film 2 will be described later. The modulus of elasticity of the cured film 2 can be controlled by appropriately selecting or controlling the irradiation conditions (irradiation amount, etc.) of the resin material and the active energy ray of the cured film 2.

Here, the elastic modulus refers to a coefficient of proportion of distortion and stress, and a material having a small distortion with respect to stress exhibits a high elastic modulus and a rigidity (a material having a small modulus of elasticity is soft). When an active energy ray-curable resin is used, the elastic modulus of the cured film 2 can be controlled according to the number of functional groups in the resin material, particle addition, and curing conditions. For example, an active energy ray-curable acrylate having two or more functional groups can be irradiated with an active energy ray of 300 mJ / cm ² or more to realize an elasticity of 4.0 GPa or more.

The cured film 2 is formed on the film base 1 in a range of 20 to 100% in the width direction in the first region R1 and in a range of 20 to 100% in the width direction in the second region R2 Respectively. 1 shows a case where the cured film 2 is formed on the film base 1 so as to cover the range of 20% in the width direction in the first region R1 and the second region R2 Respectively. In this case, in the first region R1 and the second region R2, the length in the width direction of the cured film 2 is 20% of 50 mm, that is, 10 mm.

On the other hand, Fig. 2 is a cross-sectional view along the width direction showing another structure of the optical film (F). In the optical film (F) of Fig. 2, the cured film 2 is formed so as to cover the range of 100% in the width direction in the first region R1 and the second region R2, respectively. In this case, in the first region R1 and the second region R2, the length in the width direction of the cured film 2 is 100% of 50 mm, that is, 50 mm.

Therefore, when the cured film 2 is formed so as to cover the range of 20 to 100% in the width direction in the first region R1 and the second region R2 on the film base 1, The length in the width direction of the cured film 2 in the region R1 and the second region R2 is 10 to 50 mm.

1 and 2, the cured film 2 is formed continuously from the first region R1 to the second region R2 in the film width direction, but may be formed discontinuously. For example, the cured film 2 is formed only in the first region R1 and the second region R2, and may not be formed between the first region R1 and the second region R2. In this case, the cured film 2 is formed only for the purpose of forming a hardened circular ring portion 3 described later than the protection of the surface of the film base 1. The cured film 2 is formed between the first region R1 and the second region R2 and the first region R2 is formed so as to be spaced apart from the cured film 2 by a predetermined distance in the width direction. The cured film 2 may be formed in the first region R1 and the second region R2.

A concave-convex nulling portion 3 is formed on the surface of the cured film 2 in each of the first region R1 and the second region R2. In FIGS. 1 and 2, for the sake of clarity, the knurling portion 3 is shown in a flat layer shape for the purpose of clarifying the formation region of the nulling portion 3, but actually, as shown in FIG. 3, The surface of the nulling portion 3 has a concavo-convex shape. The knurling portion 3 is formed by a knurling process in which an embossing roll having a concavo-convex pattern on its surface is heated and pressed onto the cured film 2. That is, the nulling portion 3 is formed by knurling after the formation of the cured film. At this time, by making the heating temperature of the embossing roll higher than the glass transition temperature (Tg) of the cured film 2, the burring portion 3 can be formed without causing cracks in the cured film 2. Alternatively, the embossing roll may be pushed before the curing film 2 is cured by ultraviolet irradiation or the like (for example, in a semi-cured state), and then the curing film material is completely cured to form the nulling portion 3.

The nulling portion 3 is formed on the surface of the cured film 2 in a width direction of 3 mm or more from each end in the width direction of the cured film 2. 1 and 2, when the forming width of the nulling portion 3 on the cured film 2 is d (mm), d? 3 is satisfied.

1, by pressing the embossing roll on the surface of the film substrate 1 in addition to the cured film 2 at the time of knurling the cured film 2, Thereby forming a knurling portion 4 of the kneading portion. The knurled portions may be formed beforehand in the width direction of the film base material 1 before forming the cured film 2, or knurled portions may not be formed. The knurl unit 4 is further formed (laminated) on the film base 1 at the time of forming the knurling unit 3 in the cured film 2 when the knurled part is previously formed on the film base 1, . Of course, when the cured film 2 is formed up to the end portion of the film base 1 as shown in Fig. 2, only the cured film 2 is subjected to knurling processing so that only the surface of the cured film 2 is covered with the knurled portion 3 (The nulling portion 4 is not formed).

It is possible to form the nulling portion 3 with the same hardness as that of the cured film 2 by knurling the surface of the cured film 2 and forming the nulling portion 3 as in this embodiment. As a result, even when the film base 1 is wound with a thin optical film F having a thickness of 10 to 40 탆, it is difficult for the knurl unit 3 to be crushed by its own weight or pressing force, , Blocking can be suppressed. Further, by suppressing the blocking, it is also possible to suppress the occurrence of black bands (stripe-shaped stripes appearing in the circumferential direction) due to thickness irregularity in the width direction of the optical film (F).

The cured film 2 is formed so as to cover the range of 20 to 100% in the width direction in the first region R1 and the second region R2 each having a length in the width direction of 50 mm, 2 is 10 to 50 mm in the width direction as described above. This makes it possible to form the nulling portions 3 in a width direction of 3 mm or more on the surface of the cured film 2 of the first region R1 and the second region R2. Then, by forming the nulling portion 3 on the surface of the cured film 2 in such a manner (over 3 mm in the width direction), the resistance to the width direction, that is, the winding core direction can surely be increased. Further, by forming the nulling portion 3 in a wide range of 3 mm or more in the width direction, the strength of the nulling portion 3 can be reliably ensured. As a result, winding displacement and blocking in the direction of the winding core at the time of winding the thin optical film (F) can be reliably suppressed.

In the present embodiment, since the cured film 2 has a modulus of elasticity of 4.0 GPa or more and the cured film 2 is rigid, the surface of the cured film 2 is knurled so that the above- It is possible to reliably realize the hard knurled portion 3 that exhibits the function of suppressing the knurl.

Since the cured film 2 has a low coefficient of static friction and is smooth and easy to adhere to the cured film 2, the structure of this embodiment capable of suppressing winding displacement and blocking can be realized by a structure in which the thickness in the state including the cured film 2 is The thin film optical film (F) having a thickness of 70 μm or less, furthermore 50 μm or less is very effective for winding in a long state. When the optical film F is allowed to take up a long length of time while suppressing winding displacement and blocking of the optical film F as described above, the productivity of the polarizing plate is improved when the polarizing plate is manufactured using the optical film (F) .

3 is a cross-sectional view showing the cured film 2 on an enlarged scale. In the present embodiment, the height t of the nulling portion 3 is 1 to 25 占 퐉. Here, the height t of the nulling portion 3 is the height of the surface of the cured film 2 on which the unevenness of the nulling portion 3 is not formed (the surface of the cured film 2 before the knurling process) (Maximum height) of the convex portion 3a of the nulling portion 3 from the surface The height t of the nulling portion 3 can be controlled by adjusting the pressing force of the embossing roll used at the time of knurling to the cured film 2.

When the height t of the nulling portion 3 is less than 1 占 퐉, the effect of suppressing the winding displacement by the knurling 3 becomes small and blocking between the films tends to occur at the time of winding the film. On the other hand, if the height t of the nulling portion 3 exceeds 25 탆, the convex portion 3a of the nulling portion 3 tends to collapse inward in the width direction at the time of film winding, Warpage (deformation) tends to occur in the rolls wound on the rollers, and it becomes difficult to secure a good winding state.

Therefore, by setting the height t of the nulling portion 3 in the range of 1 to 25 占 퐉, it is possible to suppress deformation of the roll while suppressing winding displacement and blocking at the time of winding the film, thereby improving the winding appearance.

In the present embodiment, the number (density) of the convex portions 3a of the nulling portion 3 on the surface of the cured film 2 is 10 to 140 per cm ² . The number of the convex portions 3a can be adjusted by selecting a suitable one among a plurality of embossing rolls having different numbers of convex portions forming a frame on the surface, and performing knurling processing.

Of the knurling (3) convex portions if the number of (3a) 10 gae / cm ² is less than, the convex portion (3a) not so low knurling (3) of the function, i.e., to suppress the above-described take-up shift and blocking The function can not be efficiently demonstrated. On the other hand, if the number of the convex portions 3a exceeds 140 pieces / cm ² , the risk of film breakage increases. That is, if the knurling process in which the number of the convex portions 3a exceeds 140 pieces / cm ² is performed, damage to the film base 1 is increased and the strength in the width direction of the film base 1 is lowered, .

Therefore, by a null in the number of convex portions (3a) of the ring (3) from 10 to 140 / cm ^2, while reliably exert the function of the knurling (3) of inhibiting the winding displacement and blocking, the breakage of the film .

When the cured film material is applied to the end portion of the film substrate 1 at the time of forming the cured film 2 on the film substrate 1, the cured film material is transferred to the back surface of the film substrate 1 , And there is a fear that a cured film is formed even on the backside thereof. In order to avoid such a situation, it is preferable to form the cured film 2 by applying the cured film material on the inner side in the width direction (opposite to the end) from the position at least 5 mm away from the end of the film substrate 1.

In the above, the functional layer such as the antireflection layer is not formed on the cured film 2, but the above-described configuration of the present embodiment can also be applied to the case of forming the functional layer. That is to say, by providing the functional layer on the cured film 2 and forming the nulling portion 3 on the cured film 2 outside the functional layer in the width direction, Can be suppressed. Further, the nulling portions 3 may be formed on the surface of the cured film 2 before formation of the functional layer, or may be formed after formation of the functional layer.

Particularly, when a layer containing a fluorine-based activator (antifouling layer) is provided as a functional layer for improving the antifouling property, winding displacement or the like easily occurs. In this case, 3 in the present embodiment is very effective.

[Details of each layer]

The details of each layer of the optical film (F) will be described below.

[Hard Coating Layer]

The hard coat layer as the above-mentioned cured film is formed of an active energy ray curable resin. The active energy ray curable type refers to a resin that is cured through a crosslinking reaction or the like by irradiation with an active ray such as ultraviolet rays or electron rays, and specifically a resin having an ethylenic unsaturated group. The active energy ray curable resin includes both an active energy ray curable isocyanurate derivative and an active energy ray curable resin other than an isocyanurate derivative.

≪ Active Energy ray curable isocyanurate derivatives >

The active energy ray curable isocyanurate derivative may be any compound having a structure in which at least one ethylenic unsaturated group is bonded to the isocyanuric acid skeleton and is not particularly limited, A compound having three or more ethylenic unsaturated groups and at least one isocyanurate ring is preferred. The ethylenic unsaturated group is preferably an acryloyl group, a methacryloyl group, a styryl group or a vinyl ether group, more preferably a methacryloyl group or an acryloyl group, and particularly preferably an acryloyl group.

L ² in the formula is a divalent linking group, preferably a substituted or unsubstituted alkyleneoxy group or polyalkyleneoxy group having 4 or less carbon atoms in which a carbon atom is bonded to an isocyanurate ring, Is an alkyleneoxy group, and they may be the same or different. R ² represents a hydrogen atom or a methyl group, and they may be the same or different. Specific compounds represented by the formula (1) are shown below, but are not limited thereto.

As other compounds, isocyanuric acid diacrylate compounds can be mentioned, and isocyanuric acid ethoxy-modified diacrylates represented by the following formula (2) are preferable.

In addition, an active energy ray-curable isocyanurate derivative of? -Caprolactone denaturation may also be used. Specifically, it is a compound represented by the following formula (3).

The - of R ₁ to R ₃ in the chemical structural formulas have the following functional groups represented by a, b, and c, and at least one of R ₁ to R ₃ is a functional group of b.

a: -H or - (CH ₂ ) n -OH (n = 1 to 10, preferably n = 2 to 6)

b = - (CH ₂ ) n O- (COC ₅ H ₁₀ ) m-COCH = CH ₂ (n = 1 to 10, preferably n = 2 to 6, m = 2 to 8)

c: - (CH ₂ ) n OR wherein R is a (meth) acryloyl group, n = 1 to 10, preferably n = 2 to 6,

Specific compounds represented by the formula (3) are shown below, but are not limited thereto.

Commercially available products of the isocyanuric acid triacrylate compound include, for example, Shin-Nakamura Kagaku Kogyo Co., Ltd., A-9300. Commercially available products of the isocyanuric acid diacrylate compound include Aronix M-215 manufactured by DOKOSEI CO., LTD. Examples of the mixture of the isocyanuric acid triacrylate compound and the isocyanuric acid diacrylate compound include Aronix M-315 and Aronix M-313 manufactured by Toagosei Co., Ltd.

Active energy of ε-caprolactone denaturation As the isocyanurate derivative of the ray-curable type, Shin-Nakamura, which is ε-caprolactone-modified tris- (acryloxyethyl) isocyanurate, A-9300-1CL, Aronix M-327 manufactured by Toagosei Co., Ltd. However, the present invention is not limited to these.

≪ Active energy ray curable resin other than isocyanurate derivative >

Examples of the active energy ray curable resin other than the isocyanurate derivative include an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxyacrylate resin, an ultraviolet curable polyol acrylate resin, Epoxy resin and the like are preferably used. Among them, an ultraviolet curable acrylate resin is preferable.

As the ultraviolet curable acrylate resin, polyfunctional acrylate is preferable. The polyfunctional acrylate is preferably selected from the group consisting of pentaerythritol polyfunctional acrylate, dipentaerythritol polyfunctional acrylate, pentaerythritol polyfunctional methacrylate and dipentaerythritol polyfunctional methacrylate Do. Here, the polyfunctional acrylate is a compound having two or more acryloyloxy groups or methacryloyl groups in the molecule.

Examples of the monomer of polyfunctional acrylate include ethylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexane diol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylol But are not limited to, ethylene glycol diacrylate, ethylene glycol dimethacrylate, ethanetriacrylate, tetramethylolmethane triacrylate, tetramethylolmethane tetraacrylate, pentaglycerol triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, Acrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tris (acryloyloxyethyl) isocyanurate, ethylene glycol Dimethacrylate, diethylene Recolled dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylol ethane trimethacrylate, tetramethylol methane trimethacrylate, But are not limited to, tetramethylolmethane tetramethacrylate, pentaglycerol trimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerin trimethacrylate, dipentaerythritol Trimethacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol penta methacrylate, dipentaerythritol hexa methacrylate, and the like.

As the active energy ray-curable resin other than the isocyanurate derivative, a monofunctional acrylate may be used. Examples of monofunctional acrylates include isobornyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, isostearyl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxy ethyl acrylate, Acrylate, isooctyl acrylate, tetrahydrofurfuryl acrylate, behenyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, cyclohexyl acrylate, . As the monofunctional acrylate, Shin Nakamura can be obtained from Kakugo Kogyo Co., Ltd. or Yuki Kagakugaku Kogyo Co., Ltd. These compounds may be used alone or in combination of two or more. Further, oligomers such as dimers, trimers, etc. of the above monomers may be used.

The viscosity of the polyfunctional acrylate is preferably 3000 mPa 占 퐏 or less at 25 占 폚, and more preferably 2000 mPa 占 퐏 or less. The above viscosity is a value measured at 25 캜 using a B-type viscometer.

When an active energy ray-curable isocyanurate derivative and an active energy ray-curable resin other than an isocyanurate derivative are used in combination in the hard coat layer, the active energy ray-curable isocyanurate derivative (A) and isocyanurate (A) :( B) = 10: 90 to 50: 50 in view of the excellent film strength (scratch resistance), which is obtained by using the active energy ray-curable resin (B) .

The hard coat layer preferably contains a photopolymerization initiator for accelerating curing of the active energy ray curable resin. As the amount of the photopolymerization initiator, it is preferable that the photopolymerization initiator: active energy ray curable resin = 20: 100 to 0.01: 100 by mass ratio.

Specific examples of the photopolymerization initiator include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone,? -Amyloxime ester, thioxanthone, and derivatives thereof, but are not limited thereto.

In order to prevent blocking and improve scratch resistance, it is preferable to add inorganic or organic fine particles to the active energy ray curable resin. Examples of the inorganic fine particles include silicon oxide, titanium oxide, aluminum oxide, tin oxide, indium oxide, ITO, zinc oxide, zirconium oxide, magnesium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, , Magnesium silicate and calcium phosphate. In particular, silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide and the like are preferably used.

It is preferable that these inorganic fine particles are coated with an organic component having a reactive functional group on a part of the surface in view of improving scratch resistance while maintaining the transparency of the optical film. As a form in which an organic component having a reactive functional group is coated on a part of the surface, for example, a compound containing an organic component such as a silane coupling agent reacts with hydroxyl groups present on the surface of the metal oxide fine particles, A form in which an organic component is adhered by interaction of a hydroxyl group present on the surface of the metal oxide fine particles with hydrogen bonding or the like, a form containing one or two or more inorganic fine particles in a polymer particle, .

Examples of the organic fine particles include polymethacrylate methyl acrylate resin powder, acryl styrene resin powder, polymethyl methacrylate resin powder, silicone resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin A resin powder, a melamine resin powder, a polyolefin resin powder, a polyester resin powder, a polyamide resin powder, a polyimide resin powder and a polyfluorinated ethylene resin powder.

Preferred examples of the organic fine particles include crosslinked polystyrene particles (for example, SX-130H, SX-200H and SX-350H manufactured by Soken Chemical Industries, Ltd.), polymethylmethacrylate-based particles (for example, MX150 and MX300, , And fluorine-containing acrylic resin fine particles. Examples of the fluorine-containing acrylic resin fine particles include commercially available products such as Nippon Paint: FS-701. Examples of the acrylic particles include Nippon Paint S-4000, and acryl-styrene particles such as Nippon Paint S-1200 and MG-251.

The average particle diameter of these fine particle powders is not particularly limited, but is preferably 0.01 to 5 mu m, particularly preferably 0.01 to 1.0 mu m. It may contain two or more kinds of fine particles having different particle diameters. The average particle diameter of the fine particles can be measured by, for example, a laser diffraction particle size distribution measuring apparatus.

The ratio of the ultraviolet-curable resin composition to the fine particles is preferably 10 to 400 parts by mass, more preferably 50 to 200 parts by mass, relative to 100 parts by mass of the resin composition.

The hard coating layer according to the present embodiment is obtained by applying the hard coat layer coating composition diluted with a solvent onto the film substrate by the following method, drying and curing it to obtain interlayer adhesion between the hard coat layer and the film substrate It is preferable from the standpoint of being easy. As the solvent, ketones or esters are preferable. Examples of the ketone include methyl ethyl ketone, acetone, cyclohexanone, and methyl isobutyl ketone. Examples of the esters include methyl acetate, ethyl acetate, butyl acetate, and propyl acetate, but are not limited thereto. Examples of the other solvent include alcohols (ethanol, methanol, butanol, n-propyl alcohol, isopropyl alcohol and diacetone alcohol), hydrocarbons (toluene, xylene, benzene, cyclohexane), glycol ethers (propylene glycol monomethyl ether , Propylene glycol monopropyl ether, ethylene glycol monopropyl ether, etc.) and the like can be preferably used.

By using these solvents in a range of 20 to 200 parts by mass with respect to 100 parts by mass of the active energy ray-curable resin, the stability as a coating composition is excellent.

The coating amount of the hard coat layer coating composition is suitably from 0.1 to 40 탆 in wet film thickness, preferably from 0.5 to 30 탆, and the dry film thickness is from 0.1 to 30 탆, preferably from 1 to 30 탆, Mu] m, particularly preferably 4 to 15 [mu] m.

The hard coat layer is coated with a hard coat layer coating composition which forms a hard coat layer by a known coating method such as a gravure coater, a dip coater, a reverse coater, a wire bar coater, a die (extrusion) Curing treatment, and, if necessary, heat treatment by UV curing.

As the light source used for the UV curing treatment, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp and the like can be used. Irradiation conditions are different, but the active line dose is generally 50 to 1000mJ / cm ^2, preferably 100 to 500mJ / cm ² according to the respective lamp.

In addition, when irradiating an active line, it is preferable that the film is carried out while applying a tensile force in the transport direction of the film, and more preferably, the tension is applied in the width direction. The tensile force to be imparted is preferably 30 to 300 N / m. The method of imparting the tension is not particularly limited, and the tension may be imparted in the conveying direction on the backroll, or in the width direction or the biaxial direction by the tenter. As a result, a film having excellent planarity can be obtained.

The hard coat layer may contain a conductive agent for imparting antistatic properties. Preferable examples of the conductive agent include metal oxide particles or a π conjugated conductive polymer. An ionic liquid is also preferably used as the conductive compound. The hard coat layer may contain a nonionic surfactant such as a silicone surfactant, a fluorine surfactant or a polyoxyether, an anionic surfactant and a fluorine-siloxane graft polymer from the viewpoints of coating properties and dispersibility of fine particles uniformly . The fluorine-siloxane graft polymer refers to a polymer of a copolymer obtained by grafting polysiloxane and / or organopolysiloxane containing at least a siloxane and / or an organosiloxane group to at least a fluorine resin. Commercially available products include ZX-022H, ZX-007C, ZX-049 and ZX-047-D manufactured by Fuji Chemical Industry Co., These components are preferably added in the range of 0.01 to 3 mass% with respect to the solid content component in the coating liquid.

The hard coat layer may be a single layer or a plurality of layers. The hard coat layer may be divided into two or more layers in order to facilitate control of hard coatability, haze, and arithmetic surface roughness (Ra) of the hard coat layer. The hard coating layer may be provided on both sides of the film substrate.

The thickness of the uppermost layer when two or more hard coating layers are provided is preferably in the range of 0.05 to 2 占 퐉. The lamination of two or more layers may be formed as a simultaneous middle layer. The simultaneous intermediate layer is a method in which two or more hard coating layers are coated on a substrate by wet on wet without a drying step to form a hard coating layer. In order to laminate the second hard coating layer wet on wet without the drying process on the first hard coat layer, it may be carried out in the order of the extrusion coater or in the simultaneous middle layer with the slot die having the plurality of slits.

The hard coat layer has a pencil hardness of not less than H, more preferably not less than 4H, which is an index of hardness. If it is 4H or more, it is not only hard to be scratched in the polarizing step of the liquid crystal display device but also excellent when used as a surface film substrate of a liquid crystal display device or a surface film of a liquid crystal display device for digital display, Film strength. The pencil hardness was obtained by humidity-adjusting the prepared optical film at a temperature of 23 DEG C and a relative humidity of 55% for 2 hours or more and then measuring the pencil hardness according to JIS S 6006, one of the standards of the Japanese Industrial Standards Committee (JIS) Measured by a pencil hardness evaluation method prescribed in JIS K5400, using a test pencil having the above-mentioned composition.

<Hayes>

The haze value of the optical film of the present embodiment is preferably 1% or less in the clear optical film. When the haze value is set to 1% or less, sufficient brightness and high contrast can be obtained when the liquid crystal display device is used outdoors such as a large-sized liquid crystal display device or a digital signage. The haze value can be measured in accordance with JIS K7105 and JIS K7136.

Further, the optical film of this embodiment may have anti-scattering properties. The blurring is a function of blurring the image reflected from the hard coating layer of the optical film or the outline of the external light, and the visibility of the reflection image is lowered so that the projection of the reflection image is not disturbed when an optical film is used for a liquid crystal display or the like. In the optical film having the antiglare property, the total haze value is preferably 3% to 40%. The surface haze value (haze due to surface scattering of the film) is preferably 3 to 40%, and the internal haze value (haze due to internal scattering) is preferably 35% or less.

[Film substrate]

The film substrate is preferably a cellulose ester film such as a triacetyl cellulose film, a cellulose acetate propionate film, a cellulose diacetate film, or a cellulose acetate butyrate film in view of easiness of production. Examples of the other films include polyester films such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate films, polyarylate films, polysulfone (including polyethersulfone) films, polyethylene films, polypropylene films , Polyvinylidene chloride films, polyvinyl alcohol films, ethylene vinyl alcohol films, syndiotactic polystyrene films, norbornene resin films, polymethylpentene films, polyether ketone films, polyether ketone imide films, poly Amide film, fluororesin film, nylon film, cycloolefin polymer film, polymethyl methacrylate film, acrylic film and the like can be used for the film substrate. The resin constituting the film may be used in combination.

The refractive index of the film base material is preferably 1.30 to 1.70, more preferably 1.40 to 1.65. The refractive index can be measured by the method of JIS K7142 using Abbe's refractometer 2T manufactured by Atago Co.,

<Cellulose ester film>

In the cellulose ester film, in the case of cellulose triacetate, the average degree of acetalization (amount of bound acetic acid) is preferably 54.0 to 62.5%, more preferably the cellulose triacetate film having an average degree of acetatization of 58.0 to 62.5% to be. When the average degree of acetalization is small, the dimensional change is large and the degree of polarization of the polarizing plate is lowered. If the average degree of acetalization is high, the solubility in a solvent is lowered and the productivity is lowered.

The film substrate preferably contains cellulose triacetate (A) having an acetyl group substitution degree of 2.80 to 2.95 and a number average molecular weight (Mn) of 125000 to less than 155000. The cellulose triacetate (A) preferably has a weight average molecular weight (Mw) of 265000 or more and less than 310000, and Mw / Mn of 1.9 to 2.1.

In addition, cellulose triacetate having an acetyl group substitution degree of 2.75 to 2.90, a number average molecular weight (Mn) of 155000 or more and less than 180,000, an Mw of 290000 or more and less than 360000, and an Mw / Mn of 1.8 to 2.0 in that pencil hardness is improved. (B) is preferably used in combination with cellulose triacetate (A). When the cellulose triacetate (A) and the cellulose triacetate (B) are used in combination, the ratio of cellulose triacetate (A): cellulose triacetate (B) is preferably in the range of 100: 0 to 20:80 by mass ratio.

(I) and (II), when the substitution degree of the acetyl group is X and the degree of substitution of the propionyl group or the butyryl group is Y, the acyl group having 2 to 4 carbon atoms is used as the substituent other than the cellulose triacetate, (II) can be used as the cellulose ester.

(I) 2.6? X + Y? 3.0

(II) 0? X? 2.5

Among them, cellulose acetate propionate is preferable, and among them, it is preferable that 1.9? X? 2.5 and 0.1? Y? 0.9. The measurement of the acyl group substitution degree can be performed in accordance with ASTM D817-96, which is one of the standards established and published by the American Society for Testing and Materials (ASTM). Cellulose diacetate is also preferably used.

The number average molecular weight (Mn) and the molecular weight distribution (Mw) of the cellulose ester can be measured using high performance liquid chromatography. The measurement conditions are as follows.

Solvent: methylene chloride

Column: Shodex K806, K805, K803G (connected with three of the products manufactured by Showa Denko K.K.)

Column temperature: 25 ° C

Sample concentration: 0.1 mass%

Detector: RI Model 504 (manufactured by GL Science)

Pump: L6000 (manufactured by Hitachi Seisakusho Co., Ltd.)

Flow rate: 1.0 ml / min

Calibration curve: Standard polystyrene STK standard Polystyrene (manufactured by TOSOH CORPORATION)

A calibration curve with 13 samples of Mw = 1000000 to 500 was used. The 13 samples are preferably used at substantially equal intervals.

&Lt; ester compound &

The cellulose ester film preferably contains an ester compound because of its excellent moisture permeability. The ester compound is preferably an ester compound having a structure obtained by reacting phthalic acid, adipic acid, at least one benzene monocarboxylic acid, and at least one alkylene glycol having 2 to 12 carbon atoms.

Examples of the benzene monocarboxylic acid component include benzoic acid, para-tert-butylbenzoic acid, orthotoluenic acid, meta-toluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normalpropylbenzoic acid, aminobenzoic acid, These may be used individually or as a mixture of two or more kinds. Most preferred is benzoic acid.

Examples of the alkylene glycol component having 2 to 12 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2- Diol (3,3-dimethylol pentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane) Hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9- , 1,12-octadecanediol, and the like, and these glycols are used singly or as a mixture of two or more kinds. Particularly preferred is 1,2-propylene glycol.

The ester compound may have an adipic acid residue and a phthalic acid residue as the structure of the final compound.

The ester compound can be produced, if necessary, in the presence of an esterification catalyst, for example, at a temperature in the range of 180 to 250 ° C for 10 to 25 hours and then subjected to an esterification reaction.

As the ester compound, an aromatic terminal ester compound can also be used. Exemplary compounds of aromatic terminal ester compounds are shown below, but are not limited thereto.

The ester compound may be a sugar ester compound. The sugar ester compound is a compound obtained by esterifying all or a part of the sugar OH groups such as the following monosaccharides, 2 sugars, 3 sugars or oligosaccharides. More specific examples include compounds represented by the formula (4) .

In the formulas, R ₁ to R ₈ represent a substituted or unsubstituted alkylcarbonyl group having 2 to 22 carbon atoms or a substituted or unsubstituted arylcarbonyl group having 2 to 22 carbon atoms. R ₁ to R ₈ may be the same or different.

Hereinafter, the compounds represented by the formula (4) are more specifically shown (as the compounds 4-1 to 4-23), but are not limited thereto.

The number average molecular weight of the ester compound is preferably 300 to 2000, and more preferably 400 to 1500. The acid value is preferably 0.08 to 0.50 mgKOH / g. The hydroxyl value is preferably 25 mgKOH / g or less, and more preferably 15 mgKOH / g or less.

The ester compound is preferably contained in the film base in an amount of 1 to 35 mass%, particularly 5 to 30 mass%. Within this range, there is no bleeding-out and the transparency is excellent.

The cellulose ester film may contain a thermoplastic acrylic resin and a cellulose ester resin.

The acrylic resin also includes a methacrylic resin. The acrylic resin is not particularly limited, but is preferably composed of 50 to 99 mass% of methyl methacrylate units and 1 to 50 mass% of other monomer units copolymerizable therewith. Examples of other copolymerizable monomers include alkyl methacrylates having 2 to 18 carbon atoms in the alkyl number, alkyl acrylates having 1 to 18 carbon atoms in the alkyl number, alpha, beta -unsaturated acids such as acrylic acid and methacrylic acid, Aromatic vinyl compounds such as styrene,? -Methylstyrene,?,? - unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide , N-substituted maleimide, and glutaric anhydride. These may be used alone, or two or more kinds of monomers may be used in combination.

Of these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, and 2-ethylhexyl acrylate are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer , Methyl acrylate or n-butyl acrylate are particularly preferably used.

The weight average molecular weight (Mw) of the acrylic resin is preferably in the range of 80000 to 500000, more preferably in the range of 1100000 to 500000. The weight average molecular weight of the acrylic resin can be measured by gel permeation chromatography, including measurement conditions. Examples of commercially available products include DELPET 60N and 80N manufactured by Asahi Chemical Industry Co., Ltd., DAIANAL BR52, BR80, BR83, BR85 and BR88 (manufactured by Mitsubishi Rayon Co., Ltd.) and KT75 (manufactured by Denki Kagaku Kogyo Co., ) And the like. Two or more acrylic resins may be used in combination.

<Additives>

For the purpose of improving the brittleness of the film substrate, acrylic particles may be contained. Examples of commercially available acrylic particles include commercially available products such as Metabolene W-341 (C2) (Mitsubishi Rayon Co., Ltd.), Chemisnow MR-2G (C3), MS- And the like.

The acrylic fine particles are preferably contained in the range of 0.5% to 30% with respect to the total mass of the resin forming the film base.

(Fine particles)

The film substrate may contain fine particles other than acrylic fine particles. From the viewpoint of slidability and storage stability, the fine particles other than the acrylic fine particles are preferably selected from the group consisting of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, fired kaolin, calcined calcium silicate, , Magnesium silicate and calcium phosphate are preferable.

Among these inorganic fine particles, silicon dioxide is preferable because of low turbidity. Silicon dioxide is preferably subjected to hydrophobic treatment in order to make both slip and haze compatible. Of the four silanol groups, two or more of them are preferably substituted with a hydrophobic substituent, and more preferably three or more thereof are substituted. The hydrophobic substituent is preferably a methyl group. The primary particle diameter of the silicon dioxide is preferably 20 nm or less, more preferably 10 nm or less.

The fine particles of silicon dioxide are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50 and TT600 (manufactured by Nippon Aerosil Co., Ltd.) . The fine particles of zirconium oxide are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by NIPPON AEROSIL CO., LTD.) And can be used. Of these, Aerosil RV122 and Aerosil R972V are particularly preferable because they have a high effect of lowering the friction coefficient while keeping the haze of the film base low, and Aerosil R812 is most preferably used. In the film base material, it is preferable that the coefficient of dynamic friction of at least one surface is 0.2 to 1.0.

(Other additives)

In order to improve the fluidity and flexibility of the composition, a plasticizer may be added to the film base. Examples of the plasticizer include phthalic acid compounds, fatty acid compounds, trimellitic acid compounds, phosphoric acid compounds, acrylic polymers, and epoxy compounds.

As the acrylic polymer, homopolymers or copolymers of acrylic acid or alkyl methacrylate are preferable. Examples of the monomer of the acrylic acid ester include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-) , s-), hexyl acrylate (n- and i-), heptyl acrylate (n- and i-), octyl acrylate (n- and i-), nonyl acrylate (n- and i-) and myristyl acrylate -, i-), acrylic acid (2-ethylhexyl), acrylic acid (? -caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2- hydroxypropyl) (2-methoxyethyl), acrylic acid (2-ethoxyethyl) and the like, or those obtained by substituting the acrylate ester with a methacrylate ester . The acrylic polymer is a homopolymer or a copolymer of the above monomers, but it is preferable that the acrylic acid methyl ester monomer units are contained in an amount of 30 mass% or more, and the methacrylic acid methyl ester monomer units are preferably 40 mass% or more. In particular, a homopolymer of methyl acrylate or methyl methacrylate is preferred.

Depending on the application, these plasticizers may be selected or used in combination. The amount of the plasticizer to be added is preferably 0.5 to 30 parts by mass with respect to 100 parts by mass of the film substrate.

It is also preferable that the film substrate contains an ultraviolet absorber. Examples of the ultraviolet absorber to be used include those based on benzotriazole, 2-hydroxybenzophenone or salicylic acid phenyl ester. For example, there can be mentioned 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5- , Triazole compounds such as 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy- Phenone, and 2,2'-dihydroxy-4-methoxybenzophenone. Among ultraviolet absorbers, an ultraviolet absorber having a molecular weight of 400 or more is difficult to volatilize at a high boiling point and is unlikely to be scattered even at high temperature molding, so that the addition of a relatively small amount can effectively improve weather resistance.

Examples of the ultraviolet absorber having a molecular weight of not less than 400 include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2- (2,2,6,6-tetramethyl-4-piperidyl) benzophenone-based compound such as bis (2,2,6,6-tetramethyl- Sebacate, and bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, or 2- (3,5-di-t-butyl- 1- [2- [3- (3,5-di-t-butoxycarbonyl) -2-n-butylmalonic acid bis (1,2,2,6,6- Propyloxy] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6- Tetramethylpiperidine, and the like. These compounds may be used alone or in combination of two or more thereof. The term &quot; hindered amine &quot; Among these compounds, preferred are 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2- -Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

In addition, various antioxidants may be added to the film base in order to improve the thermal decomposition property and thermal coloring property at the time of molding. It is also possible to add an antistatic agent to impart antistatic properties to the film substrate.

A flame retardant acrylic resin composition in which a phosphorus flame retardant is blended may be used for the film substrate. Examples of the phosphorus-based flame retardant used herein include triaryl phosphoric acid esters, diaryl phosphoric acid esters, monoaryl phosphoric acid esters, arylphosphonic acid compounds, arylphosphine oxide compounds, condensed aryl phosphoric acid esters, halogenated alkyl phosphoric acid esters, Esters, halogen-containing condensed phosphonic acid esters, halogen-containing phosphorous acid esters, and the like, or a mixture of two or more thereof.

Specific examples thereof include triphenyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, tris (β-chloroethyl) phosphate, tris (dichloropropyl) Tris (tribromoneopentyl) phosphate, and the like.

It is required that the film base material can withstand use under a higher temperature environment because higher luminance is required by use in outdoor applications such as digital signage. If the tensile softening point of the film base material is 105 캜 to 145 캜, it can be judged that it exhibits sufficient heat resistance, and it is preferable to control preferably 110 캜 to 130 캜.

As a specific measuring method of the tensile softening point, for example, an optical film is cut into 120 mm (length) x 10 mm (width) using a tensile testing machine (RTC-1225A manufactured by ORIENTEC Co., Ltd.) The temperature is maintained at a heating rate of 占 폚 / min, and the temperature at the time when the temperature becomes 9N is measured three times, and the average value is obtained.

From the viewpoint of heat resistance, the film substrate preferably has a glass transition temperature (Tg) of 110 캜 or higher. More preferably, it is 120 DEG C or more. Particularly preferably 150 ° C or higher.

The term "glass transition temperature" as used herein refers to a glass transition temperature measured at a heating rate of 20 ° C / min using a differential scanning calorimeter (DSC-7 made by Perkin Elmer), and the glass transition temperature (Tmg).

Further, when the film substrate is used in a liquid crystal display device used particularly outdoors, the dimensional change rate (%) of the film substrate is preferably less than 0.5%, and more preferably less than 0.3%.

Further, in the film base, it is preferable that the number of defects with a diameter of 5 m or more in the film surface is one per 10 cm square or less. More preferably at most 0.5 / 10 cm square, further preferably at most 0.1 / 10 cm square. The defect means defects in the film (defective foams) in the film due to the rapid evaporation of the solvent in the drying step of the solution film formation, foreign matter (foreign matter defect) in the film due to foreign matter contained in the film forming solution, It also refers to the portion of the surface of the roll, such as a transfer or scratch, whose shape changes. The diameter of the defect refers to the diameter when the defect has a circular shape, and when the defect is not circular, the range of the defect is determined by observing with a microscope by the following method, and the maximum diameter is defined as the diameter of the circumscribed circle.

The range of the defect is the shadow size when the defect is observed with the transmitted light of the differential interference microscope when the defect is bubble or foreign matter. When the defect is a change in surface shape such as a transfer of a roll scratch or a scratch, the size is confirmed by observing the defect as reflected light of a differential interference microscope. In addition, when observed with reflected light, if the size of the defect is unclear, aluminum or platinum is deposited on the surface and observed.

In order to obtain a film having excellent durability expressed by the frequency of defects with high productivity, it is necessary to precisely filter the polymer solution immediately before the pouring, to increase the cleanliness around the pore, and to set the drying conditions after the pouring stepwise Thus, it is effective to effectively suppress foaming and dry.

If the number of defects is more than 1/10 cm square, for example, if a tensile force is applied to the film at the time of processing in a subsequent process or the like, the film may be broken from the defect point and the productivity may be lowered. Further, when the diameter of the defect is 5 mu m or more, it can be visually confirmed by observing the polarizing plate or the like, and a bright spot may be generated when used as an optical member.

Further, even when the defects can not be visually confirmed, when the hard coat layer is formed on the film, the coating composition of the hard coat layer can not be uniformly applied, resulting in defects (coating omission).

Further, the film substrate is preferably at least 10%, more preferably at least 20% in at least one direction in the measurement according to JIS K7127 (1999).

The upper limit of the elongation at break is not particularly limited, but is practically about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film caused by foreign matter or foaming.

The thickness of the film substrate is preferably 10 占 퐉 or more. More preferably at least 20 mu m.

The upper limit of the thickness of the film base material is not particularly limited, but when the film is formed into a film by a solution casting method, the upper limit is about 250 탆 from the viewpoint of coatability, foaming, solvent drying and the like. The thickness of the film base material can be suitably selected in accordance with the use.

Therefore, the thickness of the film base of the present embodiment is preferably 10 to 250 占 퐉, more preferably 20 to 100 占 퐉. From the viewpoint of thinning of the optical member, it is particularly preferable that the thickness is 10 to 40 占 퐉.

The film substrate preferably has a total light transmittance of 90% or more, and more preferably 93% or more. The practical upper limit is about 99%. In order to achieve excellent transparency expressed by the total light transmittance, it is necessary to prevent introduction of an additive or a copolymerizable component that absorbs visible light, remove impurities in the polymer by high-precision filtration, It is effective to reduce it.

The retardation of the film base material is preferably in the range of 0 to 50 nm in the in-plane retardation (Ro) at a wavelength of 590 nm and in the retardation (Rth) in the thickness direction of -10 to 50 nm. When an optical film is constituted by using a film base having retardation in this range, interference fringes caused by birefringence can be satisfactorily suppressed when the optical film is used, for example, in a constituent member for a touch panel.

The above-mentioned Ro and Rth are values defined by the following formulas (I) and (II).

(I) Ro = (nx-ny) xd

(II) Rth = {(nx + ny) / 2-nz} xd

Ny is the index of refraction in the direction orthogonal to the slow axis within the plane of the film substrate, nz is the index of refraction in the thickness direction of the film base, d is the index of refraction of the film base, And thickness (nm), respectively. The above retardation can be obtained at a measurement wavelength of 590 nm under the environment of 23 deg. C and 55% RH using, for example, KOBRA-21ADH (Ojieiso Kiki K.K.).

The retardation can be adjusted by kinds and amounts of the above-mentioned ester compounds and plasticizers, film thickness of the film substrate, stretching conditions and the like.

It is also possible to reduce the surface roughness of the film contacting portion (cooling roll, calender roll, drum, belt, coating base in a solution film, transport roll, etc.) at the time of film formation to reduce the surface roughness of the film surface, It is effective to reduce light diffusion and reflection on the surface of the film.

(Film Formation of Film Substrate)

Next, an example of the film-forming method of the film base material is described, but the present invention is not limited to this.

As the film forming method of the film substrate, a manufacturing method such as an inflation method, a T-die method, a calendering method, a cutting method, a fusing method, an emulsion method, and a hot press method can be used. From the viewpoints of suppressing coloration, suppressing foreign matter defects, suppressing optical defects such as die lines, etc., film formation by the flexible method is preferable. For the film formation by the flexible method, there are a solution casting method and a melt casting method.

(Organic solvent)

The organic solvent useful for forming the dope when the film substrate is prepared by the solution softening method can be used without limitation as long as it dissolves the cellulose ester-based resin and other additives at the same time.

Examples of the chlorine-based organic solvent include methylene chloride and the non-chlorine-based organic solvent includes methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, Ethyl, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3 , 3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro- -Propanol, nitroethane and the like, and methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used.

The dope preferably contains a linear or branched aliphatic alcohol having 1 to 4 carbon atoms in an amount of 1 to 40 mass% in addition to the above-mentioned organic solvent. When the proportion of alcohol in the dope is high, the web is gelled to facilitate separation from the metal support. When the proportion of alcohol is small, the dissolution of the acrylic resin and the cellulose ester resin in the non-chlorinated organic solvent system is promoted .

Particularly, in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms, at least a total of 15 to 45 mass% of an acrylic resin, a cellulose ester resin and an acrylic particle are dissolved, Composition.

Examples of the straight chain or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol and tert-butanol. Of these, ethanol is preferable because of its low drip stability, relatively low boiling point, and good drying properties.

(Solution softening method)

The film substrate can be produced by a solution casting method. In the solution casting method, a process of preparing a dope by dissolving a resin and an additive in a solvent, a process of forming a dope on a belt-shaped or drum-shaped metal support, a process of drying a dope as a web, A step of stretching or maintaining the width of the web, a step of drying, and a step of winding the finished film.

The concentration of the cellulose ester resin in the dope is preferable because the drying load after the concentration of the cellulose ester resin in the dope is softened to the metal support can be reduced. However, if the concentration of the cellulose ester resin is too high, It gets worse. The concentration at which they are compatible is preferably 10 to 35 mass%, and more preferably 15 to 25 mass%.

The metal support in the casting step is preferably mirror-finished on the surface, and as the metal support, a stainless steel belt or a drum finished by plating the cast iron surface is preferably used.

The width of the cast may be 1 to 4 m. The surface temperature of the metal support of the flexible process is set to a temperature not higher than -50 DEG C and not foaming by boiling of the solvent. The higher the temperature, the faster the drying speed of the web can be. However, if the temperature is too high, the web may be foamed or the planarity may deteriorate.

The temperature of the metal support is suitably determined in the range of 0 to 100 캜, more preferably 5 to 30 캜. Alternatively, it is preferable that the web be gelled by cooling to peel off the metal support in a state containing a large amount of residual solvent.

The method of controlling the temperature of the metal support is not particularly limited, but there is a method of blowing hot air or cold air, or a method of bringing hot water to the back side of a metal support. The use of hot water is preferable because the heat transfer is performed efficiently and the time until the temperature of the metal support becomes constant is short.

In the case of using warm air, in consideration of the temperature drop of the web due to the latent heat of evaporation of the solvent, it is possible to use wind at a temperature higher than a desired temperature while preventing warming while using warm air above the boiling point of the solvent. Particularly, it is preferable that the temperature of the metal support and the temperature of the drying wind are changed during the period from the time when the softening is peeled to the time when the drying is performed efficiently.

In order for the cellulose ester-based film to exhibit good planarity, the amount of the residual solvent when peeling the web from the metal support is preferably from 10 to 150% by mass. The lower limit of the residual solvent amount is preferably 20 to 40% by mass, particularly preferably 20 to 30% by mass. The upper limit of the amount of the residual solvent is preferably 60 to 130% by mass, particularly preferably 70 to 120% by mass. Further, the amount of residual solvent is defined by the following formula.

Amount of residual solvent (mass%) = {(M-N) / N} 100

Here, M is the mass of the sample taken from the web or film at any point in time during or after the production, and N is the mass after heating the M at 115 ° C for 1 hour.

In the drying process of the cellulose ester film or the cellulose ester resin / acrylic resin film, it is preferable that the web is peeled off from the metal support and dried to make the residual solvent amount not more than 1% by mass, more preferably not more than 0.1% By mass or less, particularly preferably 0 to 0.01% by mass or less.

In the stretching step, the stretching can be performed sequentially or simultaneously with respect to the conveying direction (MD direction) of the web (film) and the transverse direction (TD direction) perpendicular thereto. The stretching magnifications in the biaxial directions orthogonal to each other are preferably set in the range of 1.0 to 2.0 times in the MD direction and 1.07 to 2.0 times in the TD direction, respectively, and 1.0 to 1.5 times in the MD direction and 1.07 To 2.0 times as high as that in the case of the present invention. For example, there are a method in which a peripheral speed difference is applied to a plurality of rolls, and a stretching is performed in the MD direction using the speed difference between rolls therebetween, a method in which both ends of the web are fixed with clips or pins, And stretching in the MD direction. Similarly, stretching in the transverse direction and stretching in the TD direction, or stretching in the MD / TD direction simultaneously and stretching in the MD / TD both directions.

The stretching in the width direction or the stretching in the width direction in the film forming step is preferably performed by a tenter, and a pin tenter or a clip tenter may be used. The film transport tension in the film forming process in a tenter or the like is preferably 120 N / m to 200 N / m, more preferably 140 N / m to 200 N / m, and more preferably 140 N / m to 160 N / desirable.

(Tg-30) to (Tg + 100) deg. C, and more preferably from (Tg-20) to (Tg + 80) deg. C , More preferably (Tg-5) to (Tg + 20) 占 폚.

The glass transition temperature of the film substrate can be controlled in accordance with the kind of the material constituting the film and the ratio of the constituent material. The glass transition temperature of the film substrate upon drying is preferably 110 DEG C or higher, more preferably 120 DEG C or higher. The glass transition temperature of the film substrate is preferably 190 占 폚 or lower, and more preferably 170 占 폚 or lower. At this time, the glass transition temperature of the film substrate can be determined by a method described in JIS K7121.

When the film is stretched at a temperature of 150 ° C or more and a stretching magnification of 1.15 times or more, the surface is preferably roughened. Properly roughening the surface of the film is preferable because it not only improves the slidability but also improves the surface processability, particularly the hard coat layer adhesion. The surface arithmetic mean roughness (Ra) of the film substrate is preferably 2.0 nm to 4.0 nm, more preferably 2.5 nm to 3.5 nm.

In the film drying process, a roll drying system (a system in which a web is alternately passed through a plurality of rolls arranged at upper and lower sides and dried) or a system in which a web is transported and dried by a tenter is employed.

(Melting and softening method)

The film substrate may be formed by a melt-blown method. The melt-softening method refers to a method of heating a composition containing an additive such as a resin and a plasticizer to a temperature at which the fluidity is exhibited, and thereafter flexing the melt containing the fluid cellulose ester. A method in which the film forming material is heated to express the fluidity thereof and then extruded on a drum or an endless belt to form a film is also included in the melting and fusing method.

More specifically, the molding method for heating and melting can be classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, and an extension molding method. Among these molding methods, a melt extrusion molding method is preferable in terms of mechanical strength and surface precision. It is preferable that a plurality of raw materials used for melt extrusion are usually previously kneaded and pelletized.

The pelletization can be carried out by using a known method. For example, a dry cellulose ester, a plasticizer and other additives may be fed into an extruder as a feeder, kneaded using a single- or twin-screw extruder, extruded into a strand shape from a die, and then pelletized by water- have.

The additives may be mixed before being supplied to the extruder, or may be supplied to the extruder by individual feeders.

Small amounts of additives such as particles and antioxidants are preferably mixed in advance in order to mix them uniformly.

It is preferable that the extruder is capable of pelletizing so as to suppress the shear force and not to deteriorate the resin (decrease in molecular weight, coloration, gel formation, etc.), and to work at as low a temperature as possible. For example, in the case of a twin-screw extruder, it is preferable to use a deep groove type screw to rotate in the same direction. In the kneading uniformity, an engaging type is preferable.

Film formation is carried out using the pellets obtained as described above. Of course, it is also possible to feed the powder of the raw material directly to the extruder as a feeder, and to form the film as it is without pelletizing.

The pellets are extruded using a single-screw extruder or a twin-screw extruder at a melt temperature of about 200 to 300 ° C, filtered with a filter such as a leaf disc type filter to remove foreign matters, , Nip the film with the cooling roll and the elastic touch roll, and solidify on a cooling roll.

When introducing the material from the feed hopper into the extruder, it is preferable to prevent the oxidative decomposition or the like under vacuum or in an inert gas atmosphere under reduced pressure. Further, it is preferable that the extrusion flow rate of the pellets is stably performed by introducing a gear pump.

In addition, a stainless steel fiber sintered filter is preferably used as the filter used for removing the foreign matter. The stainless steel fiber sintering filter is formed by integrally forming a stainless steel fiber body in an intricately intertwined state, compressing it, and sintering the contact portions. The filtration accuracy can be adjusted by varying the density depending on the thickness of the fiber and the amount of compression .

Additives such as plasticizers and particles may be mixed with the resin in advance, or added in the middle of the extruder. In order to uniformly add it, it is preferable to use a mixing device such as a static mixer.

The film temperature at the touch roll side when nipping the film with the cooling roll and the elastic touch roll is preferably Tg + Tg + 110 deg. C or lower. A known roll having an elastic body on its surface can be used as the elastic touch roll used for this purpose. The elastic touch roll is also referred to as a nip pressurized rotating body, and a touch roll disclosed in Japanese Patent No. 3194904, Japanese Patent No. 3422798, Japanese Patent Application Laid-Open No. 2002-36332, Japanese Patent Application Laid-Open No. 2002-36333 and the like can be preferably used. A commercially available elastic touch roll may also be used.

When the film is peeled from the cooling roll, it is preferable to control the tension to prevent deformation of the film.

Further, it is preferable that the film obtained as described above is stretched by a stretching operation after passing through a process in contact with a cooling roll. As the stretching method, a known roll stretcher, a tenter or the like can be preferably used. The stretching temperature is preferably in the range of Tg to Tg + 60 占 폚 of the resin constituting the film.

Before winding the formed film, knurling (embossing) may be carried out at both ends for slitting and cutting the end portion of the width of the product to prevent adhesion during winding and scratching. Knurling can be performed by heating an embossing roll having a pattern of irregularities on its surface and pressing it on the film. In addition, the clip holding portions at both ends of the film are usually cut off because the film is deformed and can not be used as a product.

[Functional layer]

In the optical film of the present embodiment, a functional layer such as an antistatic layer, a back coating layer, an antireflection layer, an inactive layer, an adhesive layer, and a barrier layer can be formed.

(Back coating layer)

In the optical film of the present embodiment, a back coating layer may be formed on the surface of the film base opposite to the side where the hard coating layer is formed, in order to prevent curling or adhesion.

Examples of the particles of the inorganic compound to be added to the back coating layer include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, tin oxide, , Hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate.

The amount of the particles contained in the back coating layer is preferably 0.1 to 50 mass% with respect to the binder. As the binder, a cellulose ester resin such as diacetyl cellulose is preferable.

In addition, when the back coating layer is provided, the increase in haze is preferably 1.5% or less, more preferably 0.5% or less, and particularly preferably 0.1% or less.

(Antireflection layer)

The optical film of the present embodiment can be used as an antireflection film having a function of preventing reflection of external light by providing an antireflection layer on the upper layer of the hard coat layer.

It is preferable that the antireflection layer is laminated in consideration of the refractive index, the film thickness, the number of layers, the layer order, and the like so as to reduce the reflectance by optical interference. It is preferable that the antireflection layer is formed by combining a low refractive index layer having a refractive index lower than that of the film substrate supporting the support or a high refractive index layer and a low refractive index layer having a refractive index higher than that of the film substrate as a support. Particularly preferably, three antireflection layers composed of three or more refractive index layers and having different refractive indices from the support side are used as the intermediate refractive index layer (a layer having a higher refractive index than the support and a refractive index lower than that of the high refractive index layer) / a high refractive index layer / Low refractive index layer are preferably laminated in this order. Alternatively, an antireflection layer having a layer structure of four or more layers in which two or more high refractive index layers and two or more low refractive index layers are alternately laminated is also preferably used.

As the layer structure of the antireflection film, the following structure is conceivable, but the present invention is not limited thereto.

Film substrate / hard coating layer / low refractive index layer

Film substrate / hard coating layer / medium refractive index layer / low refractive index layer

Film base material / hard coating layer / medium refractive index layer / high refractive index layer / low refractive index layer

Film base material / hard coating layer / high refractive index layer (conductive layer) / low refractive index layer

Film substrate / hard coat layer / antiglare layer / low refractive index layer

<Low Refractive Index Layer>

The low refractive index layer preferably contains silica-based fine particles, and its refractive index is preferably in the range of 1.30 to 1.45 at a measurement wavelength of 550 nm at 23 占 폚.

The film thickness of the low refractive index layer is preferably from 5 nm to 0.5 占 퐉, more preferably from 10 nm to 0.3 占 퐉, and most preferably from 30 nm to 0.2 占 퐉.

As for the composition for forming a low refractive index layer, it is preferable that the silica-based fine particles have at least one outer layer and at least one particle of porous or hollow particles therein. Particularly, it is preferable that the particles having the respective outer layers and the inside of which are porous or hollow are hollow silica-based fine particles.

The composition for forming a low refractive index layer may contain an organosilicon compound represented by the following formula (OSi-1), a hydrolyzate thereof, or a polycondensate thereof.

(OSi-1): Si (OR) ₄

In the formulas, R represents an alkyl group having 1 to 4 carbon atoms. As the organosilicon compound represented by the above formula, specifically, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and the like are preferably used.

Further, the composition for forming a low refractive index layer is preferably a compound having a thermosetting and / or photo-curable property mainly comprising a fluorine-containing compound containing fluorine atoms in a range of 35 to 80% by mass and containing a crosslinkable or polymerizable functional group . Specifically, it is a fluorine-containing polymer or a fluorine-containing sol-gel compound. As the fluorine-containing polymer, for example, a hydrolyzate or a dehydration condensation product of a perfluoroalkyl group-containing silane compound [for example, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane] , A fluorine-containing copolymer having a fluorine-containing monomer unit and a crosslinkable reactive unit as a constituent unit. In addition, a solvent, a silane coupling agent, a curing agent, a surfactant, and the like may be added to the composition for forming a low refractive index layer, if necessary.

&Lt; High refractive index layer &

The refractive index of the high refractive index layer is preferably in the range of 1.4 to 2.2 at a measurement wavelength of 550 nm at 23 占 폚. The thickness of the high refractive index layer is preferably 5 nm to 1 탆, more preferably 10 nm to 0.2 탆, and most preferably 30 nm to 0.1 탆. The means for adjusting the refractive index can be achieved by adding metal oxide fine particles or the like to the high refractive index layer. The refractive index of the metal oxide fine particles to be used is preferably 1.80 to 2.60, and more preferably 1.85 to 2.50.

The kind of the metal oxide fine particles is not particularly limited and may be at least one selected from Ti, Zr, Sn, Sb, Cu, Fe, Mn, Pb, Cd, As, Cr, Hg, Zn, Al, Mg, Si, A metal oxide having one kind of element may be used. These metal oxide fine particles may be doped with a small amount of atoms such as Al, In, Sn, Sb, Nb, a halogen element, and Ta, or may be a mixture thereof. Among them, at least one metal oxide fine particle selected from zirconium oxide, antimony oxide, tin oxide, zinc oxide, indium tin oxide (ITO), antimony doped tin oxide (ATO) and zinc antimonate is used as a main component Particularly preferred. It is particularly preferable to contain zinc antimonate particles.

The average particle diameter of the primary particles of these metal oxide fine particles is 10 nm to 200 nm, and particularly preferably 10 nm to 150 nm. The average particle diameter of the metal oxide fine particles can be measured from an electron microscope photograph by a scanning electron microscope (SEM) or the like, but may be measured by a particle size distribution meter using a dynamic light scattering method or a static light scattering method. If the particle diameter is too small, aggregation tends to occur and the dispersibility is deteriorated. If the particle size is too large, the haze increases remarkably, which is undesirable. The shape of the metal oxide fine particles is preferably a fine particle shape, a spherical shape, a cubic shape, a spindle shape, a needle shape, or an irregular shape.

The metal oxide fine particles may be surface-treated with an organic compound. By surface modifying the surface of the metal oxide fine particles with an organic compound, the dispersion stability in the organic solvent is improved, and the control of the dispersion particle diameter is facilitated, and coagulation and sedimentation over time can be suppressed. Therefore, the surface water content of the organic compound is preferably from 0.1% by mass to 5% by mass, more preferably from 0.5% by mass to 3% by mass, based on the metal oxide fine particles. Examples of the organic compound used in the surface treatment include polyols, alkanolamines, stearic acid, silane coupling agents and titanate coupling agents. Among them, a silane coupling agent is preferable. Two or more kinds of surface treatments may be combined.

The high refractive index layer may contain a pi conjugated system conductive polymer. The? -conjugated conductive polymer can be used as long as it is an organic polymer having a main chain of? -conjugated system. Examples thereof include polythiophenes, polypyrroles, polyanilines, polyphenylene, polyacetylenes, polyphenylene vinylene, polyacenes, polythiophene vinylenes and copolymers thereof. From the standpoint of ease of polymerization and stability, polythiophenes, polyanilines and polyacetylenes are preferred.

The? -conjugated conductive polymer exhibits sufficient conductivity and solubility in the binder resin as it is, but in order to further improve conductivity and solubility, a functional group such as an alkyl group, a carboxyl group, a sulfo group, an alkoxy group, a hydroxyl group or a cyano group is introduced You can. The ratio of the polymer and the binder is preferably 10 to 400 parts by mass, more preferably 100 to 200 parts by mass, relative to 100 parts by mass of the polymer, relative to 100 parts by mass of the polymer.

The high refractive index layer may contain an ionic compound. As the ionic compound, an imidazole ryumgye, pyridinium-based, alicyclic amine-based, aliphatic amine-based, and the cation of an aliphatic phosphonium nyumgye, BF ₄ ^-, PF ₆ ^- inorganic ionic, such as, CF ₃ SO ₂ ^-, ( CF ₃ SO ₂ ) ₂ N ^- , CF ₃ CO ₂ ^-, and the like.

[Polarizing plate]

Next, a polarizing plate using the optical film of this embodiment will be described. The polarizing plate can be manufactured by a general method. The back side of the optical film of the present embodiment is subjected to alkali saponification treatment and the treated optical film is bonded to at least one side of the polarizing film produced by immersion stretching in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution . Further, the optical film of the present embodiment may be bonded to the other surface of the polarizing film, or the above-described film substrate may be bonded.

In addition, by using an optical compensation film (retardation film) having a retardation (Ro) of 20 to 70 nm and a retardation (Rt) of 70 to 400 nm in the film thickness direction at a wavelength of 590 nm, It is also possible to use a polarizing plate capable of increasing the viewing angle. Such a polarizing plate can be produced, for example, by the method described in Japanese Patent Application Laid-Open No. 2002-71957. It is also preferable to use an optical compensation film having an optically anisotropic layer formed by aligning a liquid crystal compound such as a discotic liquid crystal. For example, an optically anisotropic layer can be formed by the method described in Japanese Patent Application Laid-Open No. 2003-98348.

Examples of commercially available polarizing plate film substrates that are preferably used include KC8UX2MW, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC4UEW, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC4FR-1, KC4FR- KC4UE (manufactured by Konica Minolta Opto), and the like.

The polarizing film, which is a main component of the polarizing plate, is an element that allows only light of a polarization plane in a certain direction to pass through. A typical polarizing membrane currently known is a polyvinyl alcohol polarizing film, which includes a polyvinyl alcohol film stained with iodine and a dichroic dye stained, but the deflecting film is not limited thereto.

The polarizing film is obtained by forming a film of a polyvinyl alcohol aqueous solution, uniaxially stretching it, dyeing it, dyeing it, uniaxially stretching it, and preferably durability treatment with a boron compound. The polarizing film preferably has a film thickness of 5 to 30 탆, preferably 8 to 15 탆.

On one side of the polarizing film, one side of the optical film of the present embodiment is bonded to form a polarizing plate. Preferably, it is bonded by an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like.

[Adhesive layer]

The adhesive layer used for one side of the film substrate for bonding to the substrate of the liquid crystal cell is preferably optically transparent and exhibits appropriate viscoelasticity and adhesive properties.

Specifically, as the adhesive layer, an adhesive such as an acrylic copolymer, an epoxy resin, a polyurethane, a silicone polymer, a polyether, a butyral resin, a polyamide resin, a polyvinyl alcohol resin, May be used. Using these materials, a pressure-sensitive adhesive layer can be formed by forming a film by a drying method, a chemical hardening method, a thermal hardening method, a heat melting method, a photo hardening method, or the like and curing it. Among them, an acrylic copolymer is preferred because it is easy to control physical properties of the adhesive, and is excellent in transparency, weather resistance, durability and the like.

<Liquid Crystal Display Device>

By incorporating the polarizing plate produced using the optical film of the present embodiment in a display device, an image display device having excellent visibility can be produced.

The optical film of the present embodiment is incorporated in a polarizing plate and is used as a reflective type, a transmissive type, a transflective type liquid crystal display or a liquid crystal display of TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type) And is preferably used for liquid crystal display devices of various driving methods.

The optical film of the present embodiment can also be used for a member for a touch panel of a liquid crystal display device with a touch panel. In this case, visibility and durability against pen input (scratches due to sliding) can be improved.

(Example)

Hereinafter, specific examples of the present invention will be described as examples, but the present invention is not limited to these examples.

(Example 1)

4 is a cross-sectional view along the width direction showing the schematic structure of the optical film (F) of Example 1. Fig. Since the optical film F has a layer structure symmetrical with respect to the cross section perpendicular to the width direction passing through the center in the width direction, the first region R1 of the optical film F and the second region Only the first region R1 is shown in the region R2 and the second region R2 is not shown (the same applies to the cross-sectional views shown below).

In Example 1, a triacetylcellulose film (TAC) was used as the film substrate 1, and pentaerythritol diacrylate resin was used as the cured film material. The cured film material is applied from the first region R 1 to the second region R 2 in the width direction of the film substrate 1 and is cured by irradiation with ultraviolet rays to form a cured film having an elastic modulus of 4.5 GPa 2) was formed. The ultraviolet irradiation condition at this time was an illuminance of 100 mW / cm ² and an irradiation dose of 300 mJ / cm ² . Thereafter, the optical film F is subjected to a knurling process using an embossing roll to form a knurling portion 3 on the cured film 2 and to form a knurling portion 4 on the film base 1 ) Was formed to prepare an optical film (F).

Here, the end position in the width direction of the film base material 1 is A. A position 50 mm inward from the position A in the width direction (opposite to the end A) is referred to as D. In this case, the first area R1 and the second area R2 become the area between the A and D (50 mm width). It is also assumed that the cured film 2 is formed in the width direction from the position B1 to the position B2 on the film substrate 1 in each of the first region R1 and the second region R2 , And the entire nulling portion (nulling portion 3 + nulling portion 4) is formed from the position C1 to the position C2 in the width direction. It is also assumed that the position B1 占 폚 is located on the side of the end A than the position B2 占 폚. It is assumed that the position C1 is coincident with the position A and the position B2 is coincident with the position D unless otherwise specified.

In the first embodiment, in the first region R1 and the second region R2, the curing film 2 is formed in a range of 45 mm (90% between ADs) between B1 and B2, 3) + nulling portion 4) was 15 mm between C1 and C2. That is, in the first region R1 and the second region R2, the formation range of the nulling portion 4 on the film base 1 is 5 mm between A (C1) and B1, The formation range of the nulling portion 3 was 10 mm between B1 and C2.

In addition, the board height (t) of the ring (3) is 10㎛, and the number of boards was raised portion (3a) of the ring (3) is 70 / cm ^2. The measurement of the height t of the nulling portion 3 was carried out by a contact type film thickness measuring instrument TOF-6R (manufactured by Yama Bunden Co., Ltd.), and the number of convex portions 3a was measured by a microscope VHX- 2000 (manufactured by Keans Co., Ltd.). The thickness of the film base material 1 used was 30 mu m.

(Example 2)

In the second embodiment, the formation range (C1-C2) of the entire nulling part (the nulling part 3 + the nulling part 4) from the film end in the first area R1 and the second area R2, And the formation range of the blanking portion 3 (between B1 and C2) on the cured film 2 was 3 mm, an optical film (F) was produced in the same manner as in Example 1.

(Example 3)

In Example 3, an optical film (F) was produced in the same manner as in Example 1 except that the height (t) of the nulling portion 3 was 1 占 퐉.

(Example 4)

In Example 4, an optical film (F) was produced in the same manner as in Example 1, except that the height (t) of the nulling portion 3 was 25 占 퐉.

(Example 5)

In Example 5, an optical film (F) was produced in the same manner as in Example 1 except that the number of projections (3a) of the nulling portion (3) was 10 pieces / cm ² .

(Example 6)

In Example 6, the optical film (F) was produced in the same manner as in Example 1 except that the number of convex portions 3a of the nulling portion 3 was 140 pieces / cm ² .

(Example 7)

In Example 7, an optical film (F) was produced in the same manner as in Example 1 except that the film base material 1 to be used had a thickness of 10 탆.

(Example 8)

In Example 8, an optical film (F) was produced in the same manner as in Example 1 except that the film base material 1 to be used had a thickness of 40 탆.

(Example 9)

In Example 9, the ultraviolet irradiation condition was set to 80 mW / cm ² , the irradiation amount was set to 100 mJ / cm ² , and ultraviolet rays were irradiated to the cured film material to adjust the elastic modulus of the cured film 2 to 4.0 GPa An optical film (F) was produced in the same manner as in Example 1.

(Example 10)

Fig. 5 is a cross-sectional view along the width direction showing the schematic structure of the optical film (F) of Example 10. Fig. In Example 10, the formation range (B1 to B2) of the cured film 2 was set to 10 mm (20% between AD) in the first region (R1) and the second region (R2) (The nulling portion 3 + the nulling portion 4) was set to be 50 mm. That is, on the cured film 2 of the first region R1 and the second region R2, the forming range (between B1 and C2) of the nulling portion 3 is set to 10 mm. Other than that, an optical film (F) was produced in the same manner as in Example 1.

(Example 11)

Fig. 6 is a cross-sectional view along the width direction showing the schematic structure of the optical film (F) of Example 11. Fig. In Example 11, the formation range of the cured film 2 (between B1 and B2) was 50 mm (100% between AD) in the first region R1 and the second region R2, 2) of the knurl unit 3 (between B1 and C2) was set to 15 mm. That is, in the eleventh embodiment, since the end position B1 of the cured film 2 coincides with the end position A (C1) of the first region R1 and the second region R2, The knurl unit 3 is formed only on the cured film 2 (the knurl unit 4 is not formed on the film substrate 1). Other than that, an optical film (F) was produced in the same manner as in Example 1.

(Example 12)

7 is a cross-sectional view along the width direction showing the schematic structure of the optical film (F) of Example 12. Fig. The cured film 2 is formed only in the first region R1 and the second region R2 and the end position B2 of the cured film 2 is formed in the width direction (Toward the position A).

More specifically, in the first region R1 and the second region R2, the formation range (between B1 and B2) of the cured film 2 is set to be from 20 mm to 20 mm in the width direction from the end position A (40% between ADs), and the forming range of the nulling portion 3 (between B1 and C2) was 15 mm. That is, in the twelfth embodiment, since the end position B1 of the cured film 2 coincides with the end position A (C1) of the first region R1 and the second region R2, The knurl unit 3 is formed only on the cured film 2 (the knurl unit 4 is not formed on the film substrate 1). Other than that, an optical film (F) was produced in the same manner as in Example 1.

(Example 13)

8 is a cross-sectional view along the width direction showing the schematic structure of the optical film (F) of Example 13. Fig. The cured film 2 was formed only in the first region R1 and the second region R2 and the end position B2 of the cured film 2 was formed in the same manner as in Example 12, (Position A) side with respect to the position D as shown in Fig.

More specifically, the formation range of the cured film 2 in the first region R1 and the second region R2 is changed from a position B1 that is 10 mm inward in the width direction to a position A in the width direction, (The width of the knurling portion 3 and the nulling portion 4) in the range of 30 mm from the position A to the position B2 of 40 mm in the width direction (60% between AD) C2) was set to 20 mm. In this case, on the cured film 2 of the first region R1 and the second region R2, the forming range (between B1 and C2) of the nulling portion 3 is 10 mm. Other than that, an optical film (F) was produced in the same manner as in Example 1.

(Example 14)

In the fourteenth embodiment, the formation range (between C1 and C2) of the nulling portion (nulling portion 3 + nulling portion 4) from the film end portion is set to be 10 mm and the formation range (between B1 and C2) of the knurling portion 3 on the cured film 2 was 5 mm, an optical film (F) was produced in the same manner as in Example 1.

(Example 15)

In Example 15, an optical film (F) was produced in the same manner as in Example 1 except that the height (t) of the nulling portion (3) was 0.5 탆.

(Example 16)

In Example 16, an optical film (F) was produced in the same manner as in Example 1 except that the height (t) of the nulling portion (3) was 30 占 퐉.

(Example 17)

In Example 17, an optical film (F) was produced in the same manner as in Example 1 except that the number of convex portions 3a of the nulling portion 3 was 5 pieces / cm ² .

(Example 18)

In Example 18, an optical film (F) was produced in the same manner as in Example 1 except that the number of convex portions 3a of the nulling portion 3 was 150 pieces / cm ² .

(Example 19)

Example 19 was repeated except that the irradiation condition of the ultraviolet ray was set to 50 mW / cm ^{2 at an} illuminance of 50 mJ / cm ² and the ultraviolet rays were irradiated to the cured film material so that the modulus of elasticity of the cured film 2 was 3.5 GPa An optical film (F) was produced in the same manner as in Example 1.

(Comparative Example 1)

In the comparative example 1, the formation range (between C1 and C2) of the nulling part (nulling part 3 + nulling part 4) from the end of the film in the first area R1 and the second area R2 is And an optical film F was produced in the same manner as in Example 1 except that the range of formation of the nulling portion 3 (between B1 and C2) on the cured film 2 was 2 mm.

(Comparative Example 2)

Fig. 9 is a cross-sectional view along the width direction showing the schematic structure of the optical film (F) of Comparative Example 2. Fig. In Comparative Example 2, the formation range (B1-B2) of the cured film (2) is 5 mm (10% between AD) in the first region (R1) and the second region (Between the ring portion 3 and the nulling portion 4) (the distance between C1 and C2) was 45 mm. That is, in Comparative Example 2, a nulling portion 4 is formed only on the film base 1 of the first region R1 and the second region R2, and a nulling portion 3 is formed on the cured film 2 Did not do it. Other than that, an optical film (F) was produced in the same manner as in Example 1.

<Evaluation>

The optical films (F) produced in the above-mentioned Examples 1 to 19 and Comparative Examples 1 and 2 were wound and evaluated for wound displacement in the winding core direction, gauge band (attachment and blocking) The results are shown in Table 1.

Here, the evaluation criteria of the winding deviation are as follows.

?: No winding displacement occurs at all, which is good.

A: A slight deviation in winding occurred, but it is a problem-free level.

DELTA: A further winding displacement occurred, but it is at a level at which no problem occurs in practice.

X: Wrapping deviation occurs to such a degree that it is a problem, and it is defective.

The gauge band evaluation criteria are as follows.

?: No gauge band is generated at all, which is good.

○: A little gauge band occurred but no problem level.

[Delta]: A gage band was further generated, but the level was practically problematic.

X: Gauge band occurs to such a degree that it is a problem, and it is defective.

The evaluation standard of the winding appearance is as follows.

?: The roll is not deformed, and the winding state is good.

A: A slight warp occurred in the roll, but it is a problem-free level.

DELTA: There was more warpage in the roll, but the level was practically unproblematic.

X: Deflection of the roll occurs to a degree, which is defective.

Evaluation criteria of the film breakage are as follows.

?: No breakage of the film occurs at all, which is good.

?: A slight breakage of the film occurred but a problem-free level.

DELTA: The film was further broken, but the level was practically unproblematic.

X: Rupture of the film occurs to such a degree that it is a problem, and it is defective.

From the results shown in Table 1, it is understood that in Examples 1 to 19, the knurl portion 3 on the cured film 2 is formed in a width direction of 3 mm or more, and the winding deviation and the gage band are good (?), Level (?) Or a level (?) That is not problematic in actual use. On the other hand, in Comparative Examples 1 and 2, the knurl portion 3 on the cured film 2 was less than 3 mm in the width direction, and both the winding deviation and the gage band occurred, and the result was defective (X). Therefore, by forming the nulling portion 3 over the cured film 2 in the width direction by 3 mm or more, it is possible to suppress the winding deviation and the gage band.

Further, in Example 15, even if the knurl portion 3 is formed over the cured film 2 in the width direction by 3 mm or more, the winding displacement and the gage band are further generated as compared with the first embodiment. This is considered to be because the height of the nulling portion 3 is as small as 0.5 占 퐉 and the winding gap and the gage band can not be sufficiently suppressed by the nulling portion 3.

Further, in Example 16, the wound roll was deformed, and the winding state was inferior to that in Example 1. This is because the height of the nulling portion 3 is as large as 30 占 퐉 so that the convex portion 3a easily collapses inward in the width direction at the time of winding and as a result, do.

On the other hand, in Examples 1 to 14, the height of the nulling portion 3 is in the range of 1 to 25 占 퐉, and it is good (?) For any of winding displacement, gage band, to be. Therefore, it is preferable that the height of the nulling portion 3 is 1 to 25 占 퐉 in order to suppress deformation of the roll while suppressing the winding displacement and blocking, thereby improving the winding appearance.

In Example 17, even if the knurling portion 3 is formed over the cured film 2 in a width direction of 3 mm or more, the winding deviation and the gage band are further generated as compared with the first embodiment. This knurling (3) the number of the convex portions (3a) 5 number / and cm ^2, the number of convex portions (3a), so too low, a null function to suppress the winding displacement and blocked by the ring section 3 of the It can not be demonstrated efficiently.

Further, in Example 18, breakage of the film during winding was further generated as compared with Example 1. This, when the channel row of the convex portion (3a) Number of the knurl finish that is 150 / cm ² of the ring (3), away given a great damage to the film base (1), whereby the transverse direction strength of the film .

On the other hand, in Examples 1 to 14, the number of the convex portions 3a of the nulling portion 3 was 10 to 140 / cm ² , and the result was good (?) For either winding displacement, gage band or film breakage , And no problem level (?). Thus, it can be said that in order to suppress the winding misalignment, blocking and film rupture, knurling 3 dogs from 10 to 140. The number of convex portions (3a) / cm ² is preferably of.

In Example 19, even if the knurl portion 3 is formed over the cured film 2 in the width direction by 3 mm or more, the winding deviation and the gauge band are further generated as compared with the first embodiment. This is because the elastic modulus of the cured film 2 is as low as 3.5 GPa and the desired hardness can not be imparted to the nulling portion 3 formed on the surface of the cured film 2, .

On the other hand, in Examples 1 to 14, the cured film 2 had an elastic modulus of 4.0 GPa or more, and no winding displacement or gauge band was observed. This is considered to be because the knurl unit 3 has a function of suppressing the occurrence of winding deviation and gauge band by firmly forming the nulling portion 3 on the surface of the cured film 2. Therefore, in order to reliably exhibit the function of the nulling portion 3 for suppressing winding displacement or the like, it is preferable that the elastic modulus of the cured film 2 is 4.0 GPa or more.

INDUSTRIAL APPLICABILITY The present invention can be applied to various functional films such as a polarizing plate protective film, a retardation film, a viewing angle enlarging film, and the like, which are used in liquid crystal display devices, for example.

1: Film substrate
2:
3: Null ring
F: Optical film
R1: first region
R2: second region

Claims (4)

An optical film having a cured film formed on a film substrate having a thickness of 10 to 40 占 퐉,
When the respective regions from the both ends in the width direction of the film substrate to 50 mm are referred to as a first region and a second region,
The cured film is formed on the film substrate so as to cover a range of 20 to 100% in the width direction in the first region and a range of 20 to 100% in the width direction in the second region,
A knurled portion of a concavo-convex shape is formed on the surface of the cured film in each of the first region and the second region by knurling after forming the cured film,
Wherein the knurling portion is formed on the surface of the cured film in a range of 3 mm or more in the width direction from each end of the cured film. The method according to claim 1,
And the height of the knurled portion is 1 to 25 占 퐉. 3. The method according to claim 1 or 2,
And the number of convex portions of the knurled portion is 10 to 140 per 1 cm &lt; ^{2 &} gt ;. 4. The method according to any one of claims 1 to 3,
Wherein the cured film has an elastic modulus of 4.0 GPa or more.

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