JP2009223129A - Method for manufacturing optical film, optical film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical film causing no deformation such as black band and blocking irrespective of its large width and thin film and to provide the optical film manufactured by this manufacturing method, a polarizing plate using this optical film, and a liquid crystal display element using this polarizing plate. <P>SOLUTION: This method for manufacturing the optical film having deviation in local film thickness in the direction of width being 0.2-2.5 μm comprises an application process for applying a functional coating on the film being a continuously moving basic material, a knurling process for knurling the film being the basic material to have height of 14-30 μm before or after applying the functional coating, a drying process for drying the film being the basic material on which the functional coating is applied, and a winding process for winding the film being the basic material on which the functional coating is applied. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a coating type optical film having no film deformation such as a black band or blocking even if it is a wide and thin optical film, an optical film produced by the production method, and a polarizing plate using the optical film And a liquid crystal display element using the polarizing plate.

  In recent years, various display devices such as a liquid crystal television, a plasma display (PDP), and an organic EL display have been developed in addition to a CRT, and their screen sizes are increasing. With an increase in screen size and image quality, an optical film on which an antireflection layer or the like is formed is attached to the front surface of a display device in order to improve visibility. Moreover, in such a display apparatus, a hand may touch directly or an object may contact, and it is easy to damage it. Therefore, in general, an optical film with a hard coat layer in which a hard coat layer is formed on a base film for preventing scratches and an antireflection layer or the like formed thereon is used.

  As such an optical film for a display device, a wide film having a size of 1000 mm or more, and further 1400 mm or more has recently been required due to the enlargement of the screen. In addition, a thin base film having a thickness of about 60 μm has been used for mobile phones and notebook computers. Therefore, a resin film such as cellulose ester is used as the base film, and a hard coat layer, an antireflection layer, an antifouling layer or an antiglare layer is formed thereon.

However, when the base film becomes wider for widening as described above, or when the thickness of the base film is reduced for thinning, after forming the hard coat layer and the antireflection layer, Or, at the stage of winding the finished optical film, the winding shape deteriorates, the stripes that appear as black bands on the circumference (hereinafter referred to as black bands) and the adhesion between films called blocking are likely to occur, which is severe In some cases, deformation may occur, leading to a decrease in yield. The optical film must be free of deformation, and for stabilization of the winding state, a technique for embossing called optical knurling on the optical film is known. The thickness regulation of the knurling and the embossing height of the knurling part are known. A standard, multi-row embossing technique is disclosed (see, for example, Patent Documents 1 to 3). However, in the recent production of wide and thin films, there is a demand for a technology that can prevent further black bands and blocking and has higher production efficiency.
JP-A-2005-77795 JP 2005-99245 A JP 2006-224607 A

  Therefore, in view of the above problems, an object of the present invention is to provide a method for producing an optical film having no film deformation such as a black band or blocking even if it is a wide and thin optical film, an optical film produced by the production method, A polarizing plate using a film and a liquid crystal display element using the polarizing plate are provided.

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

1.
A coating step of applying a functional film on the surface of a continuously moving film, a knurling step of knurling the film, a drying step of drying the film coated with the functional film, and after the drying step In a method for producing an optical film, including a winding step of winding the film,
The local film thickness deviation in the width direction of the film after the drying step is 0.2 to 2.5 μm,
The said knurling process is processed to the surface side which apply | coats the functional film of the said film, and knurling height is 14-30 micrometers, The manufacturing method of the optical film characterized by the above-mentioned.

2.
2. The method for producing an optical film according to 1, wherein a film thickness of the film before the coating step is 35 to 100 μm.

3.
3. The method for producing an optical film according to 1 or 2, wherein the film thickness deviation in the width direction of the film before the coating step is 0.1 to 2.0 [mu] m.

4).
4. The method for producing an optical film according to claim 1, wherein a local film thickness deviation in the width direction of the functional film after the drying step is 0.1 to 0.5 μm.

5.
A coating liquid containing 0.02 to 10.00 mass% of particles having a volume average particle size of 0.01 to 1 μm is applied to the surface of the film opposite to the surface to which the functional film is applied. 5. The method for producing an optical film according to any one of 1 to 4.

6).
6. The method for producing an optical film according to any one of 1 to 5, wherein the knurling treatment is performed on an outer side in a width direction of a region of the film to which the functional film is applied.

7).
The method for producing an optical film according to any one of 1 to 6, wherein a tension during winding in the winding step is 30 to 400 N / m.

8).
The method for producing an optical film according to any one of 1 to 7, wherein a winding length of the film in the winding step is 500 to 4000 m.

9.
9. The method for producing an optical film according to any one of 1 to 8, wherein the film has a width of 1000 to 4000 mm.

10.
10. The method for producing an optical film according to any one of 1 to 9, wherein the wound film is held at a temperature of 50 to 150 [deg.] C. for 3 to 30 days after the winding step.

11.
An optical film produced by the method for producing an optical film according to any one of 1 to 10.

12
A polarizing plate using the 11 optical film.

13.
A liquid crystal display device using 12 polarizing plates.

  A method for producing an optical film having no film deformation such as a black band or blocking, even if it is a wide and thin optical film according to the present invention, an optical film produced by the production method, a polarizing plate using the optical film, and the polarizing plate A liquid crystal display element using can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

  The method for producing an optical film in the present invention includes a coating process for applying a functional film to a continuously moving film, a knurling process for knurling the film, and a drying process for drying the film coated with the functional film. And a winding step of winding the film after the drying step, and the local film thickness deviation in the width direction of the film after the drying step is 0.2 to 2.5 μm, and the knurling treatment is performed. The film is processed on the side to which the functional film is applied, and the knurling height is 14 to 30 μm.

  Thus, even if it rolls the produced film in roll shape by making the local film thickness deviation in the width direction of the film after a drying process into 0.2-2.5 micrometers and the knurling height in a knurling process be 14-30 micrometers. Deterioration of the winding shape occurs, and a good film can be produced without causing adhesion of a film called a black band on the circumference (hereinafter referred to as a black band) or a film called blocking.

  The local film thickness deviation in the width direction of this optical film means that the functional film is applied to the base film, and the thickness of the optical film after drying is measured in the width direction. It is defined as the maximum thickness difference (μm).

  As a film thickness measuring device, a commercially available transmission infrared film thickness meter, β-ray film thickness meter, or the like can be used. Examples of the transmission infrared film thickness meter include the RX-100 type and RX-200 type manufactured by Kurabo Industries. An example of a β-ray thickness gauge is a Teijin Engineering Co., Ltd. β-ray thickness gauge. This measurement method can also be used to measure the local film thickness deviation of the base film described below and the local film thickness deviation of the functional film after drying applied on the base film.

  The knurling height will be described with reference to FIG. In FIG. 1, two functional films (3 and 4 in the figure) are formed on the base film F, and the knurling process is performed twice on the outer side in the film width direction of the functional film (1, 2 in the figure). The applied state is shown. The knurling height T is a difference between the surface of the functional film and the height of the knurling portion.

  When the local film thickness deviation in the width direction of the optical film exceeds 2.5 μm, the film thickness varies greatly, distortion occurs during winding, and a black band is generated. Also, local film thickness deviations of less than 0.2 μm are difficult to manufacture.

  When the knurling height T is less than 14 μm, the height necessary for preventing blocking or black band is insufficient, and when it is 30 μm or more, the thickness of the winding end increases (ear-earing failure) and the film is deformed. appear.

The functional film may be composed of one layer or three or more layers. Further, the knurling process may be performed once or three times or more, and the final knurling part has only to have a predetermined height. Further, the knurling treatment may be formed before or after the functional film is applied. Furthermore, when a multilayer functional film is formed, a knurling process may be performed between the respective coating steps. Moreover, you may perform both before an application | coating process and after an application | coating process. In short, it is sufficient that a functional film is formed on the base film and a predetermined knurling height is formed before winding in a roll shape. As a method for imparting knurling, it can be formed by pressing a heated embossing roll on the film. Processing can be performed at room temperature, but it is preferable to process the embossing roll at a surface temperature of Tg + 20 ° C. or higher and a melting point (Tm) + 30 ° C. or lower. Fine embossing is formed on the embossing roll. By pressing this embossing roll, unevenness can be formed on the film and the end can be made bulky. The shape of the unevenness is not particularly limited, and various patterns are used. The ratio of the area of the portion observed as the protrusion of each embossed line to the entire embossed part is preferably about 15 to 50%, and when the protrusions included in each of these lines are discontinuous, The number is preferably about 10 to 30 per cm ² . The width (H) of the knurling part is not particularly limited, but is 0.5 cm to 3 cm, preferably 1 to 2.5 cm, particularly preferably 1.5 to 2 cm.

  Moreover, the film thickness of a film (hereinafter referred to as a base film) before the coating step in the present invention is preferably 35 μm to 100 μm, and more preferably 40 μm to 80 μm.

  Moreover, in this invention, it is preferable that the local film thickness deviation in the width direction of a base film is 0.1-2.0 micrometers. When the thickness exceeds 2.0 μm, the variation in film thickness is large, and there is a possibility that distortion occurs during winding and a black band or blocking occurs. Also, local film thickness deviations less than 0.1 μm are difficult to manufacture.

  Moreover, in this invention, it is preferable that the local film thickness deviation of the functional film after a drying process exists between 0.1-0.5 micrometer. If this value exceeds 0.5 μm, the surface of the functional film has a large variation, so that the film is likely to be locally deformed, and distortion may occur during winding, resulting in the occurrence of black bands and blocking. Also, local film thickness deviations less than 0.1 μm are difficult to manufacture.

  In the present invention, a coating liquid containing 0.02 to 10.00 mass% of particles having a volume average particle diameter of 0.01 to 1 μm is provided on the opposite surface (back surface) of the film coated with the functional film. It is preferable to apply. More preferably, content is 0.05 mass%-5.00 mass%, More preferably, it is 0.08 mass%-2.00 mass%. By applying such a coating solution, the coefficient of dynamic friction on the back surface of the film can be reduced, and the generation of scratches and foreign matter on the functional film and the adsorption of dust and the like when wound in a roll shape can be suppressed. If the particle size exceeds 1 μm or the content exceeds 5.00% by mass, the back surface may become rough, and the functional film may be damaged during winding, or the winding state may be deteriorated. It is not preferable. On the other hand, when the particle size is less than 0.01 μm or the content is less than 0.05% by mass, the effect of reducing the dynamic friction coefficient decreases, which is not preferable.

  Further, the location of the knurling portion may be either the inside or outside of the coating width, but it is preferably applied to the outside in the width direction of the region where the functional film is applied in the base film as shown in FIG. When this is knurled at the application site, the functional film is damaged and broken due to the high temperature and high pressure energy during the knurling process, which tends to cause foreign matter. Moreover, it is not preferable to apply a functional film to the knurling portion because the emboss height varies in the longitudinal direction.

  Further, in the film winding process of the present invention, the film is wound with tension, and the tension is preferably 30 to 400 N / m. If the tension at the time of winding is less than 30 N / m, a phenomenon in which the upper part of the winding film sinks over time, that is, a so-called horse spine phenomenon is likely to occur. This phenomenon may cause sticking failure and is not preferable.

  In addition, since the winding tension is too weak, especially when winding a long length of 2000 m or more, it is unpreferable because it is unwound during transportation of the finished product roll or unwound due to the unwinding tension during re-feeding. On the other hand, if the tension at the time of winding exceeds 400 N / m, a film sticking failure due to tightening tends to occur, which is not preferable.

  Moreover, the winding length of the optical film in the present invention (referring to the length of the optical film wound in a roll shape after the base film is subjected to the knurling treatment through the coating step) is 500 to 4000 m. Is preferred. If the winding length of the optical film is less than 500 m, it is not preferable because the number of windings of the obtained optical film is too large and it is difficult to cope with packaging.

  Further, if the winding length of the optical film exceeds 4000 m, it is not preferable because failure such as blocking is likely to occur.

  Moreover, it is preferable that the width | variety of the optical film in this invention is 1000-4000 mm.

  The winding core used when winding the optical film in a roll shape may be any material as long as it is a cylindrical core, but is preferably a hollow plastic core, and the plastic material will be described later. Any heat-resistant plastic that can withstand the heat treatment temperature is used, and examples thereof include phenol resins, xylene resins, melamine resins, polyester resins, and epoxy resins. A thermosetting resin reinforced with a filler such as glass fiber is preferable.

  The number of windings to these winding cores is preferably 100 windings or more, more preferably 500 windings or more, the winding thickness is preferably 5 cm or more, and the width of the base film is 1.0 m or more. It is preferable that it is 1.4 m or more.

  Moreover, in this invention, after winding an optical film in roll shape, it is preferable to heat-process in a roll state. When heat treatment is not performed in a roll state, heat treatment is performed while being transported, but in that case, the heating temperature is too high, such as partial curing failure due to heating unevenness or thermal deformation of the base film. Problems arise. Further, if the passage time of the heat treatment zone is extended without increasing the heating temperature, the production rate is slowed and the manufacturing cost is increased. On the other hand, in a roll state, if the heat treatment is performed in a range of 50 ° C. to 150 ° C. and a period of 3 to 30 days, partial curing failure or thermal deformation of the base film This is preferable because the heat treatment can be performed without reducing the production speed. Moreover, as for the temperature increase rate at the time of heat processing, 10 to 30 degreeC / day is preferable.

  When the heating rate during the heat treatment exceeds 30 ° C./day, the film is rapidly expanded and wrinkles or the like are likely to enter near the core, which is not preferable. Moreover, productivity is remarkably inferior when it is less than 10 ° C./day, which is not realistic.

  There is no particular limitation on the temperature rising pattern, and a linear, curvilinear or stepwise pattern may be taken for optimization. Further, there may be a temporary temperature drop during the temperature rising period.

  Although there is no restriction | limiting in particular in the temperature fall after heat processing, In order to make shrinkage | contraction of a film uniform, it is preferable to reduce temperature by the temperature fall pattern of 10 to 30 degree-C / day similarly to temperature rise.

  In order to stably perform the heat treatment, it is preferably performed in a place where the temperature and humidity can be adjusted, and particularly preferably performed in a heat treatment chamber such as a clean room without dust.

  Moreover, when performing the said heat processing, it is preferable to rotate a roll, and the rotation has a preferable speed | velocity of 1 rotation or less per minute, and may be continuous or intermittent rotation.

Next, components relating to the method for producing an optical film of the present invention will be described in detail.
(Base film)
The base film that can be used in the present invention will be described.

  The substrate film according to the present invention is preferably easy to manufacture, good adhesion to the hard coat layer, optically isotropic, optically transparent, and the like. Listed as a requirement.

  The term “transparent” as used in the present invention means that the visible light transmittance is 60% or more, preferably 80% or more, and particularly preferably 90% or more.

  The base film according to the present invention is preferably at least one resin selected from cellulose ester resin, polyester resin, polycarbonate resin, polyethersulfone resin, polyacrylate resin, cycloolefin resin, and acrylic styrene resin. .

  For example, cellulose ester film, polyester film, polycarbonate film, polyarylate film, polysulfone (including polyethersulfone) film, polyethylene terephthalate, polyethylene naphthalate polyester film, polyethylene film, polypropylene film, cellophane, Cellulose diacetate film, cellulose triacetate, cellulose acetate butyrate film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, polycarbonate film, cycloolefin polymer film (Arton (manufactured by JSR)) ZEONEX, ZEONOR (made by ZEON CORPORATION) ), Polymethyl pentene film, polyether ketone film, polyether ketone imide film, a polyamide film, a fluororesin film, a nylon film, polymethyl methacrylate film, may be mentioned acrylic film or a glass plate or the like. Among them, cellulose triacetate film, polycarbonate film, and polysulfone (including polyethersulfone) film are preferable. In the present invention, cellulose ester film (for example, product names KC8UX2MW, KC4UX2MW, KC8UY, KC4UY, KC5UN, KC12UR (Konica Minolta Opt) From the viewpoint of production, cost, transparency, isotropy, adhesiveness, and the like. These films may be films produced by melt casting film formation or films produced by solution casting film formation.

  The base film according to the present invention preferably has a thickness of 35 μm to 100 μm, more preferably 40 μm to 80 μm. The film thickness of a base film can be made into a desired film thickness by adjusting the film-forming conditions at the time of film manufacture.

The moisture permeability is preferably 200 g / m ² · 24 hours or less as a value measured according to JIS Z 0208 (25 ° C., 90% RH), more preferably 10 to 180 g / m ² · 24 hours. Or less, particularly preferably 160 g / m ² · 24 hours or less. In particular, it is preferable that the film thickness is 40 μm to 80 μm and the moisture permeability is within the above range.

  Moreover, it is preferable that the width | variety of a base film is 1.0m-4.0m. Further, in terms of production efficiency and utilization efficiency when the functional film is applied to a display device, it is particularly preferably 1.4 m to 3.0 m. When such a wide substrate film is used, the knurling portion can be provided not only in the width direction end portion of the substrate film but also inside thereof. That is, a plurality of rows of knurling portions can be provided on the base film. For example, if a knurling part is provided at the center of the base film, blocking that tends to occur at the center of the wide base film can be effectively prevented.

  As the optical properties of the roll film as a base film, those having a retardation Rt in the film thickness direction of 0 nm to 300 nm and an in-plane retardation Ro of 0 nm to 1000 nm are preferably used.

  In the present invention, it is most preferable to use a cellulose ester film as the substrate film. As the cellulose ester, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate are preferable. Among them, cellulose acetate butyrate, cellulose acetate phthalate, and cellulose acetate propionate are preferably used.

  In particular, when the substitution degree of the acetyl group is X and the substitution degree of the acyl group having 2 to 22 carbon atoms is Y, the hard coat layer is formed on the base film having a mixed fatty acid ester of cellulose in which X and Y are in the following ranges. And an optical film provided with an antireflection layer is preferably used. The acyl group having 2 to 22 carbon atoms preferably includes a propionyl group or a butyryl group.

2.3 ≦ X + Y ≦ 3.0
0.1 ≦ Y ≦ 1.2
In particular, it is preferable that 2.5 ≦ X + Y ≦ 2.85 and 0.3 ≦ Y ≦ 1.2.

  When cellulose ester is used as the base film according to the present invention, the cellulose used as a raw material for the cellulose ester is not particularly limited, and examples thereof include cotton linter, wood pulp (derived from coniferous tree, derived from broadleaf tree), kenaf and the like. . Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively. When the acylating agent is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), these cellulose esters use an organic solvent such as acetic acid or an organic solvent such as methylene chloride, and It can be obtained by reacting with a cellulose raw material using a protic catalyst.

When the acylating agent is acid chloride (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804. In addition, the cellulose ester used in the present invention is obtained by mixing and reacting the amount of the acylating agent in accordance with the degree of substitution. In the cellulose ester, these acylating agents react with hydroxyl groups of cellulose molecules. Cellulose molecules are composed of many glucose units linked together, and the glucose unit has three hydroxyl groups. The number of acyl groups derived from these three hydroxyl groups is called the degree of substitution (mol%). For example, cellulose triacetate has acetyl groups bonded to all three hydroxyl groups of the glucose unit (actually 2.6 to 3.0).

  The measuring method of the substitution degree of an acyl group can be measured according to the provisions of ASTM-D817-96.

  The number average molecular weight of the cellulose ester is preferably 70000 to 250,000, since it has a high mechanical strength when molded and an appropriate dope viscosity, and more preferably 80000 to 150,000.

  These cellulose esters are pressurized by applying a cellulose ester solution (dope) generally called a solution casting film forming method onto, for example, an endless metal belt for infinite transport or a support for casting of a rotating metal drum. It is preferable to manufacture the dope from a die by casting (casting).

  The organic solvent used for the preparation of these dopes is preferably capable of dissolving the cellulose ester and having an appropriate boiling point, for example, methylene chloride, methyl acetate, ethyl acetate, amyl acetate, methyl acetoacetate, acetone, tetrahydrofuran 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-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-1-propanol, nitroethane, 1,3-dimethyl-2-imidazolidinone, etc. It is possible, organic halogen compounds such as methylene chloride, dioxolane derivatives, methyl acetate, ethyl acetate, acetone, methyl acetoacetate, and the like are preferable organic solvents (i.e., good solvent), and as.

  Moreover, as shown in the following film forming process, it is used from the viewpoint of preventing foaming in the web when the solvent is dried from the web (dope film) formed on the casting support in the solvent evaporation process. The boiling point of the organic solvent is preferably 30 to 80 ° C. For example, the good solvent described above has a boiling point of methylene chloride (boiling point 40.4 ° C), methyl acetate (boiling point 56.32 ° C), acetone (boiling point 56.56 ° C). 3 ° C.), ethyl acetate (boiling point 76.82 ° C.) and the like.

  Among the good solvents described above, methylene chloride or methyl acetate, which is excellent in solubility, is preferably used.

  It is preferable to contain 0.1 mass%-40 mass% of C1-C4 alcohol other than the said organic solvent. It is particularly preferable that the alcohol is contained at 5 to 30% by mass. After casting the dope described above onto a casting support, the solvent starts to evaporate and the alcohol ratio increases and the web (dope film) gels, making the web strong and peeling from the casting support. It is also used as a gelling solvent for facilitating the dissolution, and when these ratios are small, it also has a role of promoting dissolution of the cellulose ester of the non-chlorine organic solvent.

  Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol and the like.

  Of these solvents, ethanol is preferred because it has good dope stability, relatively low boiling point, good drying properties, and no toxicity. It is preferable to use a solvent containing 5% by mass to 30% by mass of ethanol with respect to 70% by mass to 95% by mass of methylene chloride. Methyl acetate can be used in place of methylene chloride. At this time, the dope may be prepared by a cooling dissolution method.

  The base film used in the present invention is preferably stretched at least in the width direction before the knurling step, and particularly in the width direction when the residual solvent amount is 3% by mass to 40% by mass in the solution casting step. The film is preferably stretched 1.01 to 1.5 times. More preferably, biaxial stretching is performed in the width direction and the longitudinal direction. When the residual solvent amount is 3% by mass to 40% by mass, 1.01 to 1.5 times in the width direction and the longitudinal direction, respectively. It is desirable to be stretched.

  The residual solvent amount is represented by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web (cellulose ester film containing the solvent) at an arbitrary point in time, and N is the mass when the web of M is dried at 110 ° C. for 3 hours.

  Furthermore, by performing the above-mentioned knurling after biaxial stretching, it is possible to remarkably improve the roll shape deterioration during storage of the roll-shaped optical film.

  In the present invention, the biaxially stretched cellulose ester film preferably has a light transmittance of 90% or more, more preferably 93% or more.

  When using a cellulose ester film for the optical film of the present invention, it is preferable to contain the following plasticizer. Examples of plasticizers include phosphate ester plasticizers, phthalate ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, glycolate plasticizers, citrate ester plasticizers, and polyesters. A plasticizer, a polyhydric alcohol ester plasticizer, and the like can be preferably used.

  For phosphate plasticizers, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenylbiphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. For phthalate ester plasticizers, diethyl phthalate, dimethoxy For trimellitic acid plasticizers such as ethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, diphenyl phthalate, dicyclohexyl phthalate, tributyl trimellitate, triphenyl trimellitate, triethyl For pyromellitic acid ester plasticizers such as trimellitate, tetrabutylpyromellitate, In the case of glycolate plasticizers such as lupyromelitate and tetraethylpyromellitate, triacetin, tributyrin, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, butylphthalylbutyl glycolate, etc. Citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-n-butyl citrate, acetyl tri-n- (2-ethylhexyl) citrate and the like can be preferably used. Examples of other carboxylic acid esters include trimethylolpropane tribenzoate, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters.

  As the polyester plasticizer, a copolymer of a dibasic acid such as an aliphatic dibasic acid, an alicyclic dibasic acid, or an aromatic dibasic acid and a glycol can be used. The aliphatic dibasic acid is not particularly limited, and adipic acid, sebacic acid, phthalic acid, terephthalic acid, 1,4-cyclohexyl dicarboxylic acid and the like can be used. As the glycol, ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol and the like can be used. These dibasic acids and glycols may be used alone or in combination of two or more.

  As the polyhydric alcohol ester plasticizer, a plasticizer described in JP-A-2003-12823 is preferably used.

  The amount of these plasticizers used is preferably 1% by mass to 20% by mass and particularly preferably 3% by mass to 13% by mass with respect to the cellulose ester in terms of film performance, processability and the like.

  In the optical film of the present invention, an ultraviolet absorber is preferably used.

  As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having a small absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties.

  Specific examples of ultraviolet absorbers preferably used in the present invention include, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, and the like. However, it is not limited to these.

  Specific examples of the benzotriazole-based ultraviolet absorbers include the following ultraviolet absorbers, but the present invention is not limited thereto.

UV-1: 2- (2'-hydroxy-5'-methylphenyl) benzotriazole UV-2: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole UV-3 : 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole UV-4: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl)- 5-Chlorobenzotriazole UV-5: 2- (2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl) benzotriazole UV-6: 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol)
UV-7: 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole UV-8: 2- (2H-benzotriazol-2-yl) -6 (Linear and side chain dodecyl) -4-methylphenol (TINUVIN171, manufactured by Ciba)
UV-9: Octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl- Mixture of 4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate (TINUVIN 109, manufactured by Ciba)
Moreover, although the following specific example is shown as a benzophenone series ultraviolet absorber, this invention is not limited to these.
UV-10: 2,4-dihydroxybenzophenone UV-11: 2,2'-dihydroxy-4-methoxybenzophenone UV-12: 2-hydroxy-4-methoxy-5-sulfobenzophenone UV-13: bis (2-methoxy -4-hydroxy-5-benzoylphenylmethane)
As the ultraviolet absorber preferably used in the present invention, a benzotriazole-based ultraviolet absorber and a benzophenone-based ultraviolet absorber that are highly transparent and excellent in preventing the deterioration of the polarizing plate and the liquid crystal are preferable, and unnecessary coloring is less. A benzotriazole-based ultraviolet absorber is particularly preferably used.

  Moreover, the ultraviolet absorber whose distribution coefficient described in Unexamined-Japanese-Patent No. 2001-187825 is 9.2 or more improves the surface quality of a base film, and is excellent also in applicability | paintability. In particular, it is preferable to use an ultraviolet absorber having a distribution coefficient of 10.1 or more.

  Further, the polymer ultraviolet absorbers described in the general formula (1) or general formula (2) described in JP-A-6-148430 and the general formulas (3), (6), and (7) of Japanese Patent Application No. 2000-156039 ( Alternatively, an ultraviolet absorbing polymer) is also preferably used. As a polymer ultraviolet absorber, PUVA-30M (manufactured by Otsuka Chemical Co., Ltd.) and the like are commercially available.

  The primary average particle diameter of the fine particles added to the cellulose ester film used in the present invention is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm. These fine particles preferably form secondary particles having a particle diameter of 0.1 to 5 μm and are contained in the cellulose ester film, and the preferable average particle diameter is 0.1 to 2 μm, more preferably 0.2 to 0.6 μm. Thereby, appropriate slipperiness can be given to the film surface.

  The primary average particle diameter of the fine particles used in the present invention is measured by observing particles with a transmission electron microscope (magnification 500,000 to 2,000,000 times), observing 100 particles, and using the average value, the primary value is measured. The average particle size was taken.

  The apparent specific gravity of the fine particles is preferably 70 g / liter or more, more preferably 90 to 200 g / liter, and particularly preferably 100 to 200 g / liter. A larger apparent specific gravity makes it possible to make a high-concentration dispersion, which improves haze and agglomerates, and is preferable when preparing a dope having a high solid content concentration as in the present invention. Are particularly preferably used.

  Silicon dioxide fine particles having an average primary particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more are, for example, a mixture of vaporized silicon tetrachloride and hydrogen burned in air at 1000 to 1200 ° C. Can be obtained. For example, it is marketed by the brand name of Aerosil 200V and Aerosil R972V (above, Nippon Aerosil Co., Ltd. product), and can use them.

  The apparent specific gravity described above is calculated by the following equation by taking a certain amount of silicon dioxide fine particles in a graduated cylinder, measuring the weight at this time.

Apparent specific gravity (g / liter) = silicon dioxide mass (g) / volume of silicon dioxide (liter)
Examples of the method for preparing the fine particle dispersion used in the present invention include the following three types.
<< Preparation Method A >>
After stirring and mixing the solvent and fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. The fine particle dispersion is added to the dope solution and stirred.
<< Preparation Method B >>
After stirring and mixing the solvent and fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. Separately, a small amount of cellulose triacetate is added to the solvent and dissolved by stirring. The fine particle dispersion is added to this and stirred. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.
<< Preparation Method C >>
Add a small amount of cellulose triacetate to the solvent and dissolve with stirring. Fine particles are added to this and dispersed by a disperser. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.

Preparation method A is excellent in dispersibility of silicon dioxide fine particles, and preparation method C is excellent in that silicon dioxide fine particles are difficult to re-aggregate. Among them, the preparation method B described above is a preferable preparation method that is excellent in both dispersibility of the silicon dioxide fine particles and difficulty in reaggregation of the silicon dioxide fine particles.
《Distribution method》
The concentration of silicon dioxide when the silicon dioxide fine particles are mixed with a solvent and dispersed is preferably 5% by mass to 30% by mass, more preferably 10% by mass to 25% by mass, and most preferably 15% by mass to 20% by mass. A higher dispersion concentration is preferred because the turbidity with respect to the amount added tends to be low, and haze and aggregates are improved.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

  The addition amount of silicon dioxide fine particles relative to cellulose ester is preferably 0.01 parts by mass to 5.0 parts by mass, and more preferably 0.05 parts by mass to 1.0 part by mass with respect to 100 parts by mass of cellulose ester. Preferably, 0.1 mass part-0.5 mass part is the most preferable. The larger the added amount, the better the dynamic friction coefficient, and the smaller the added amount, the less aggregates.

  As the disperser, a normal disperser can be used. Dispersers can be broadly divided into media dispersers and medialess dispersers. For dispersing silicon dioxide fine particles, a medialess disperser is preferred because of its low haze. Examples of the media disperser include a ball mill, a sand mill, and a dyno mill. Examples of the medialess disperser include an ultrasonic type, a centrifugal type, and a high pressure type. In the present invention, a high pressure disperser is preferable. The high pressure dispersion device is a device that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed at high speed through a narrow tube. When processing with a high-pressure dispersion apparatus, for example, the maximum pressure condition inside the apparatus is preferably 9.807 MPa or more in a thin tube having a tube diameter of 1 to 2000 μm. More preferably, it is 19.613 MPa or more. Further, at that time, those having a maximum reaching speed of 100 m / second or more and those having a heat transfer speed of 420 kJ / hour or more are preferable.

  Examples of the high-pressure dispersing apparatus include an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation or a nanomizer manufactured by Nanomizer, and other manton gorin type high-pressure dispersing apparatuses such as homogenizer manufactured by Izumi Food Machinery. And UHN-01 manufactured by Sanwa Machinery Co., Ltd.

  In addition, casting a dope containing fine particles so as to be in direct contact with the casting support is preferable because a film having high slip properties and low haze can be obtained.

  Moreover, after peeling and drying after casting and winding up into a roll, the optical thin film layer according to the present invention is provided. Until processing or shipment, packaging is usually performed in order to protect the product from dirt, static electricity, and the like. The packaging material is not particularly limited as long as the above purpose can be achieved, but a material that does not hinder volatilization of the residual solvent from the film is preferable. Specific examples include polyethylene, polyester, polypropylene, nylon, polystyrene, paper, various non-woven fabrics, and the like. A fiber having a mesh cloth shape is more preferably used.

  The cellulose ester film used in the present invention may have a multilayer structure by a co-casting method using a plurality of dopes.

  Co-casting is a sequential multilayer casting method in which two or three layers are configured through different dies, and a simultaneous multilayer casting method in which two or three slits are combined in a die having two or three slits. Any of the multilayer casting methods combining sequential multilayer casting and simultaneous multilayer casting may be used.

  In addition, as the cellulose ester used in the present invention, those having a small amount of bright spot foreign matter when formed into a film are preferably used. In the present invention, the bright spot foreign material is a structure in which two polarizing plates are arranged orthogonally (crossed Nicols), a cellulose ester film is arranged between them, and light from a light source is applied from one side to the other side. When the cellulose ester film is observed, the light from the light source appears to leak.

  At this time, the polarizing plate used for the evaluation is desirably composed of a protective film having no bright spot foreign matter, and a polarizing plate using a glass plate for protecting the polarizer is preferably used. The occurrence of bright spot foreign matter is considered to be one of the causes of unacetylated cellulose contained in the cellulose ester. As countermeasures, the use of cellulose ester with a small amount of unacetylated cellulose, It can be removed and reduced by filtering the dissolved dope solution. Further, the thinner the film thickness, the smaller the number of bright spot foreign matter per unit area, and the lower the content of cellulose ester contained in the film, the fewer bright spot foreign matter.

The bright spot foreign matter having a bright spot diameter of 0.01 mm or more is preferably 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, 50 pieces / cm ² or less, 30 pieces / cm. ² or less, preferably 10 pieces / cm ² or less, but it is particularly preferred that a 0.

Moreover, it is preferable that it is 200 pieces / cm < ² > or less also about 0.005 mm-0.01 mm bright spot, More preferably, it is 100 pieces / cm < ² > or less, 50 pieces / cm < ² > or less, 30 pieces / cm < ² > or less. The number is preferably 10 / cm ² or less, but particularly preferred is the case where the bright spot is zero. A thing with few also about a bright spot of 0.005 mm or less is preferable.

  When removing the bright spot foreign matter by filtration, it is preferable to filter the composition to which the plasticizer is added and mixed, rather than filtering the cellulose ester dissolved alone, because the bright spot foreign matter removal efficiency is high. As the filter medium, conventionally known materials such as glass fibers, cellulose fibers, filter paper, and fluororesins such as tetrafluoroethylene resin are preferably used, but ceramics, metals and the like are also preferably used. The absolute filtration accuracy is preferably 50 μm or less, more preferably 30 μm or less, and 10 μm or less, and particularly preferably 5 μm or less.

These can also be used in combination as appropriate. The filter medium can be either a surface type or a depth type, but the depth type is preferably used because it is relatively less clogged.
(Functional membrane)
Next, functional film formation according to the present invention will be described.

  In the present invention, examples of the functional film applied to the base film include an undercoat layer, a hard coat layer, a light diffusion layer, an antiglare layer, an adhesive layer, an antistatic layer, and an antifouling layer. A coat layer, an antiglare layer, and an antistatic layer are preferably applied. In particular, in the case of an optical film, a hard coat layer is preferably provided to increase the surface hardness of the optical film.

  Here, a hard coat layer used for an optical film or the like will be described.

  The hard coat layer is preferably a layer formed using an actinic ray curable compound (resin) that is cured by actinic rays such as ultraviolet rays, and an optical film having excellent scratch resistance can be obtained. Alternatively, a thermosetting resin may be used.

  The hard coat layer is preferably a resin layer formed by polymerizing a component containing an ethylenically unsaturated monomer. Here, the actinic radiation curable resin layer refers to a layer mainly composed of a resin that is cured through a crosslinking reaction or the like by irradiation with actinic rays such as an electron beam in addition to ultraviolet rays. Typical examples of the actinic radiation curable resin include an ultraviolet curable resin and an electron beam curable resin, but a resin that is cured by irradiation with an actinic ray other than ultraviolet rays or an electron beam may be used. Examples of the ultraviolet curable resin include an ultraviolet curable acrylic urethane resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, and an ultraviolet curable epoxy resin. I can do it.

  In general, UV-curable acrylic urethane-based resins are obtained by further reacting 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate (hereinafter referred to as acrylate, methacrylate) with a product obtained by reacting a polyester polyol with an isocyanate monomer or a prepolymer. Can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate (for example, see JP-A-59-151110).

  The UV curable polyester acrylate resin can be easily obtained by reacting polyester polyol with 2-hydroxyethyl acrylate or 2-hydroxy acrylate monomer (see, for example, JP-A-59-151112). .

  Specific examples of the ultraviolet curable epoxy acrylate resin include those obtained by reacting epoxy acrylate with an oligomer, a reactive diluent and a photoinitiator added thereto (for example, JP-A-1- No. 105738). As this photoreaction initiator, one or more kinds selected from benzoin derivatives, oxime ketone derivatives, benzophenone derivatives, thioxanthone derivatives and the like can be selected and used.

  Specific examples of ultraviolet curable polyol acrylate resins include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate. Etc. can be mentioned.

  These resins are usually used together with known photosensitizers. Moreover, the said photoinitiator can also be used as a photosensitizer. Specific examples include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and the like. Further, when using an epoxy acrylate photoreactant, a sensitizer such as n-butylamine, triethylamine, or tri-n-butylphosphine can be used. The photoreaction initiator or photosensitizer contained in the ultraviolet curable resin composition excluding the solvent component that volatilizes after coating and drying can be added in an amount of usually 1 to 10% by mass of the composition, and 2.5 to 6 It is preferable that it is mass%.

  Examples of the resin monomer include general monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, vinyl acetate, benzyl acrylate, cyclohexyl acrylate, and styrene as monomers having one unsaturated double bond. In addition, monomers having two or more unsaturated double bonds include ethylene glycol diacrylate, propylene glycol diacrylate, divinylbenzene, 1,4-cyclohexane diacrylate, 1,4-cyclohexyldimethyl adiacrylate, and the above trimethylolpropane. Examples thereof include triacrylate and pentaerythritol tetraacryl ester.

  For example, as an ultraviolet curable resin, Adekaoptomer KR / BY series: KR-400, KR-410, KR-550, KR-566, KR-567, BY-320B (above, manufactured by Asahi Denka Kogyo Co., Ltd.) Or KOHEI HARD A-101-KK, A-101-WS, C-302, C-401-N, C-501, M-101, M-102, T-102, D-102, NS-101, FT -102Q8, MAG-1-P20, AG-106, M-101-C (manufactured by Guangei Chemical Industry Co., Ltd.), or Seika Beam PHC2210 (S), PHC X-9 (K-3), PHC2213, DP- 10, DP-20, DP-30, P1000, P1100, P1200, P1300, P1400, P1500, P1600, SCR900 (above, large Manufactured by Seika Kogyo Co., Ltd.), or KRM7033, KRM7039, KRM7130, KRM7131, UVECRYL29201, UVECRYL29202 (above, Daicel UCB Corporation), or RC-5015, RC-5016, RC-5020, RC-5031, RC- 5100, RC-5102, RC-5120, RC-5122, RC-5152, RC-5171, RC-5180, RC-5181 (manufactured by Dainippon Ink & Chemicals, Inc.) or Aulex No. 340 clear (manufactured by China Paint Co., Ltd.), Sunrad H-601 (manufactured by Sanyo Chemical Industries, Ltd.), SP-1509, SP-1507 (manufactured by Showa Polymer Co., Ltd.), or RCC-15C (Grace Japan Co., Ltd.) (Manufactured by company), Aronix M-6100, M-8030, M-8060 (above, manufactured by Toagosei Co., Ltd.) or other commercially available ones can be used.

  The ultraviolet curable resin layer can be applied by a known method.

  As a solvent for coating the ultraviolet curable resin layer, for example, it can be appropriately selected from hydrocarbons, alcohols, ketones, esters, glycol ethers, and other solvents, or a mixture thereof can be used. . Preferably, propylene glycol mono (alkyl group having 1 to 4 carbon atoms) alkyl ether is prepared, and propylene glycol mono (alkyl group having 1 to 4 carbon atoms) alkyl ether ester is 5% by mass or more, more preferably 5 to 80% by mass. The solvent contained above is used.

As the light source for forming the cured film layer by photocuring reaction of the ultraviolet curable resin, any light source that generates ultraviolet rays can be used. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. The irradiation conditions vary depending on individual lamps, but the amount of light irradiated may be any degree 20~10000mJ / cm ^2, preferably from 50~2000mJ / cm ^2. It can be used by using a sensitizer having an absorption maximum in the near ultraviolet region to the visible light region.

  The UV curable resin composition is applied and dried and then irradiated with UV light from a light source. The irradiation time is preferably 0.5 seconds to 5 minutes, and 3 seconds to 2 in view of curing efficiency and work efficiency of the UV curable resin. Minutes are more preferred.

  It is preferable to add inorganic or organic fine particles to the cured film layer thus obtained in order to prevent blocking and to improve scratch resistance. Examples of inorganic fine particles include silicon oxide, titanium oxide, aluminum oxide, tin oxide, zinc oxide, calcium carbonate, barium sulfate, talc, kaolin, calcium sulfate, and the like, and examples of organic fine particles include polymethacrylic acid. Methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicone resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder Polyamide-based resin powder, polyimide-based resin powder, polyfluorinated ethylene-based resin powder, and the like can be mentioned and added to the ultraviolet curable resin composition. The average particle diameter of these fine particle powders is preferably 0.005 μm to 1 μm, and particularly preferably 0.01 to 0.1 μm.

  The proportion of the ultraviolet curable resin composition and the fine particle powder is desirably 0.1 to 30 parts by mass, preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the resin composition.

  The layer obtained by curing the ultraviolet curable resin thus formed is a hard coat layer having a center line average roughness Ra of 1 to 50 nm as defined in JIS B 0601. An antiglare layer of a degree may be used.

As a method of applying the hard coat layer to the substrate film, a known method such as a gravure coater, a spinner coater, a wire bar coater, a roll coater, a reverse coater, an extrusion coater or an air doctor coater can be used. The liquid film thickness (also referred to as wet film thickness) at the time of application is about 1 to 100 μm, preferably 0.1 to 30 μm, and more preferably 0.5 to 15 μm. The dry film thickness of the hard coat layer is preferably 1 to 20 μm.
(Antireflection layer)
In general, an antireflection layer of an optical film is formed by laminating a high refractive index layer having a refractive index higher than that of the base film and a low refractive index layer having a refractive index lower than that of the base film on the base film. Those laminated in the order of refractive index layer / low refractive index layer are preferably used from the viewpoint of reducing the reflectance.

  Note that the present invention is not limited only to lamination in this order, and may be reversed, or a medium refractive index layer having a refractive index higher than that of the base film and lower than that of the high refractive index layer during this period. The present invention can also be achieved with a configuration of three or more layers sandwiching.

  In the optical film of the present invention, at least one of a metal oxide layer, a metal oxynitride, a metal nitride, an organic polymer, and a liquid crystal compound may be formed on the above-described base film to form an antireflection layer. preferable. The antireflection layer may be formed directly on the base film, but at least one hard coat layer or other coating layer may be provided and formed on the base film having an uneven surface. This is a preferred method because it is less likely to be scratched in the process of handling the optical film and the step of making the optical film into a polarizing plate to be described later. As the other coating layer, the above-mentioned cured resin layer having a centerline average surface roughness (Ra) defined by JIS B 0601 of 0.01 to 1 μm is preferable. These are actinic radiation curable resin layers that are cured by actinic radiation such as ultraviolet rays. An optical film excellent in scratch resistance can be obtained by forming the metal oxide layer according to the present invention on the resin layer cured by such ultraviolet rays.

  As an example of the antireflection layer of the present invention, a metal oxide layer that is particularly preferably used will be described.

  The metal oxide layer is preferably used as at least one of a high refractive index layer and a low refractive index layer.

  As a method for providing the metal oxide layer, there are methods such as coating, atmospheric pressure plasma CVD, sputtering, and vapor deposition. In the present invention, the antireflection layer is preferably formed by coating.

  A method for forming the metal oxide layer by coating will be described.

  The basic structure of the optical film of the present invention will be described. The base film, the high refractive index layer, and the low refractive index layer have a refractive index that satisfies the following relationship.

  Refractive index of low refractive index layer <refractive index of base film <refractive index of hard coat layer <refractive index of high refractive index layer.

  Moreover, in this invention, it is also preferable to set it as an optical film provided with the unevenness | corrugation to a hard-coat layer or a high refractive index layer, and provided with the glare-proof antireflection layer.

In addition, a layer structure in the order of a base film, a hard coat layer (antiglare layer), a medium refractive index layer, a high refractive index layer, and a low refractive index layer is also a preferable configuration. It is preferable to impart an antiglare property to the low refractive index layer on the surface, and an antiglare layer may be provided on the surface.
(High refractive index layer)
In the present invention, in order to reduce the reflectance, a high refractive index layer having a refractive index higher than that of the base film is provided between the base film provided with the base film or the hard coat layer and the low refractive index layer. It is preferable to provide it. It is also preferable to provide a middle refractive index layer between the base film and the high refractive index layer in order to reduce the reflectance. The refractive index of the high refractive index layer is preferably 1.55 to 2.30, and more preferably 1.57 to 2.20. The film thickness of the high refractive index layer is preferably 5 nm to 1 μm, more preferably 10 nm to 0.2 μm, and most preferably 30 nm to 0.2 μm from the characteristics of the optical interference layer. The haze of the high refractive index layer is preferably 5% or less, more preferably 3% or less, and most preferably 1% or less. The strength of the high refractive index layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more, with a pencil hardness of 1 kg load. The high refractive index layer preferably contains conductive particles, inorganic particles having a composition different from the conductive particles, and a binder. The present invention can be achieved by using both conductive particles and inorganic particles or only one of them.

  The conductive particles used for the high refractive index layer preferably have a refractive index of 1.60 to 2.60, and more preferably 1.65 to 2.50. The average particle diameter of the primary particles of the conductive particles is preferably 10 to 200 nm, more preferably 20 to 150 nm, and most preferably 30 to 100 nm. The average particle diameter of the conductive fine particles can also be measured from an electron micrograph taken with a scanning electron microscope (SEM) or the like. Further, it may be measured by a particle size distribution meter using a dynamic light confusion method or a static light confusion method. If the particle size is too small, aggregation tends to occur and the dispersibility deteriorates. If the particle size is too large, the haze is remarkably increased. The shape of the conductive particles is preferably a rice grain shape, a spherical shape, a cubic shape, a spindle shape, a needle shape, or an indefinite shape.

  As for the usage-amount of electroconductive particle, 5-85 mass% is preferable in a high refractive index layer. More preferably, it is 10-80 mass%, and 20-75 mass% is the most preferable. If the amount used is small, desired effects such as refractive index and conductivity cannot be obtained, and if it is too large, film strength is deteriorated.

  The conductive particles are supplied to a coating liquid for forming a high refractive index layer in a dispersion state dispersed in a medium. As the dispersion medium for the inorganic fine particles, a liquid having a boiling point of 60 to 170 ° C. is preferably used. Specific examples of the dispersion solvent include water, alcohol (eg, methanol, ethanol, isopropanol, butanol, benzyl alcohol), ketone (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone), ketone alcohol (eg, acetone alcohol) , Esters (eg, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate), aliphatic hydrocarbons (eg, hexane, cyclohexane), halogenated hydrocarbons (eg, methylene) Chloride, chloroform, carbon tetrachloride), aromatic hydrocarbons (eg, benzene, toluene, xylene), amides (eg, dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ethers (eg, diethyl ether, dioxane, Tiger hydrofuran), ether alcohols (e.g., 1-methoxy-2-propanol), propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate. Of these, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and methanol, ethanol, and isopropanol are particularly preferable.

  The conductive particles can be dispersed in the medium using a disperser. Examples of the disperser include a sand grinder mill (eg, a bead mill with pins), a high-speed impeller mill, a pebble mill, a roller mill, an attritor, and a colloid mill. A sand grinder mill and a high-speed impeller mill are particularly preferred. Further, preliminary dispersion processing may be performed. Examples of the disperser used for the preliminary dispersion treatment include a ball mill, a three-roll mill, a kneader, and an extruder. It is also preferable to contain a dispersant.

  The high refractive index layer contains inorganic particles having a composition different from that of the conductive particles. The inorganic particles used are one kind of inorganic particles selected from the group consisting of hollow silica, colloidal silica, and magnesium fluoride.

  1-30 mass% is preferable in a high refractive index layer, as for the usage-amount of an inorganic particle, it is more preferable that it is 3-25 mass%, and 5-20 mass% is the most preferable. If the amount used is small, desired effects such as scratch resistance, adhesion, hardness, chemical resistance under high temperature and high humidity cannot be obtained, and if too large, film strength is deteriorated.

  The high refractive index layer preferably uses a polymer having a crosslinked structure (hereinafter also referred to as a crosslinked polymer) as a binder polymer. Examples of the crosslinked polymer include polymers having a saturated hydrocarbon chain such as polyolefin (hereinafter collectively referred to as polyolefin), and crosslinked products such as polyether, polyurea, polyurethane, polyester, polyamine, polyamide, and melamine resin. Among them, a crosslinked product of polyolefin, polyether and polyurethane is preferred, a crosslinked product of polyolefin and polyether is more preferred, and a crosslinked product of polyolefin is most preferred. Further, it is further preferable that the crosslinked polymer has an anionic group. The anionic group has a function of maintaining the dispersion state of the inorganic fine particles, and the crosslinked structure has a function of imparting a film forming ability to the polymer and strengthening the film. The anionic group may be directly bonded to the polymer chain or may be bonded to the polymer chain via a linking group, but is bonded to the main chain as a side chain via the linking group. Is preferred.

  Examples of the anionic group include a carboxylic acid group (carboxyl), a sulfonic acid group (sulfo), and a phosphoric acid group (phosphono). Of these, sulfonic acid groups and phosphoric acid groups are preferred. Here, the anionic group may be in a salt state. The cation that forms a salt with the anionic group is preferably an alkali metal ion. Moreover, the proton of the anionic group may be dissociated. The linking group that binds the anionic group and the polymer chain is preferably a divalent group selected from —CO—, —O—, an alkylene group, an arylene group, and combinations thereof. The crosslinked polymer which is a preferable binder polymer is preferably a copolymer having a repeating unit having an anionic group and a repeating unit having a crosslinked structure. In this case, the proportion of the repeating unit having an anionic group in the copolymer is preferably 2 to 96% by mass, more preferably 4 to 94% by mass, and most preferably 6 to 92% by mass. preferable. The repeating unit may have two or more anionic groups.

  The crosslinked polymer having an anionic group may contain other repeating units (a repeating unit having neither an anionic group nor a crosslinked structure). Other repeating units are preferably a repeating unit having an amino group or a quaternary ammonium group and a repeating unit having a benzene ring. The amino group or quaternary ammonium group has a function of maintaining the dispersed state of the inorganic fine particles, like the anionic group. The benzene ring has a function of increasing the refractive index of the high refractive index layer. The amino group, the quaternary ammonium group, and the benzene ring can obtain the same effect even if they are contained in a repeating unit having an anionic group or a repeating unit having a crosslinked structure.

  In the crosslinked polymer containing a repeating unit having an amino group or a quaternary ammonium group as a constituent unit, the amino group or quaternary ammonium group may be directly bonded to the polymer chain, or may be a side chain via a linking group. May be bonded to the polymer chain, but the latter is more preferred. The amino group or quaternary ammonium group is preferably a secondary amino group, a tertiary amino group or a quaternary ammonium group, more preferably a tertiary amino group or a quaternary ammonium group. The group bonded to the nitrogen atom of the secondary amino group, tertiary amino group or quaternary ammonium group is preferably an alkyl group, more preferably an alkyl group having 1 to 12 carbon atoms, still more preferably carbon number. 1 to 6 alkyl groups. The counter ion of the quaternary ammonium group is preferably a halide ion. The linking group that connects the amino group or quaternary ammonium group to the polymer chain is a divalent group selected from —CO—, —NH—, —O—, an alkylene group, an arylene group, and combinations thereof. Is preferred. When the crosslinked polymer includes a repeating unit having an amino group or a quaternary ammonium group, the ratio is preferably 0.06 to 32% by mass, more preferably 0.08 to 30% by mass, Most preferably, it is 0.1-28 mass%.

  The cross-linked polymer is preferably produced by a polymerization reaction at the same time as or after application of the coating liquid by preparing a coating liquid for forming a high refractive index layer by blending a monomer for generating a cross-linked polymer. Each layer is formed with the production of the crosslinked polymer. The monomer having an anionic group functions as a dispersant for inorganic fine particles in the coating solution. The monomer having an anionic group is preferably used in an amount of 1 to 50% by mass, more preferably 5 to 40% by mass, and still more preferably 10 to 30% by mass with respect to the inorganic fine particles. The monomer having an amino group or a quaternary ammonium group functions as a dispersion aid in the coating solution. The monomer having an amino group or a quaternary ammonium group is preferably used in an amount of 3 to 33% by mass based on the monomer having an anionic group. These monomers can be made to function effectively before application of the coating liquid by a method of forming a crosslinked polymer by a polymerization reaction simultaneously with or after application of the coating liquid.

  Examples of monomers having two or more ethylenically unsaturated groups include esters of polyhydric alcohols and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, penta Erythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate , Pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene and its derivatives ( 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (eg, divinyl sulfone), acrylamide (eg, methylenebisacrylamide), methacrylamide, and the like Can be mentioned. Commercially available monomers may be used as the monomer having an anionic group and the monomer having an amino group or a quaternary ammonium group. As a commercially available monomer having a commercially available anionic group, KAYAMAPMPM-21, PM-2 (manufactured by Nippon Kayaku Co., Ltd.), Antox MS-60, MS-2N, MS-NH4 (manufactured by Nippon Emulsifier Co., Ltd.) , Aronix M-5000, M-6000, M-8000 series (manufactured by Toagosei Chemical Industry Co., Ltd.), Biscote # 2000 series (manufactured by Osaka Organic Chemical Industry Co., Ltd.), New Frontier GX-8289 (Daiichi Kogyo Seiyaku) NK ester CB-1, A-SA (manufactured by Shin-Nakamura Chemical Co., Ltd.), AR-100, MR-100, MR-200 (manufactured by Eighth Chemical Industry Co., Ltd.), and the like. It is done. Examples of commercially available monomers having a commercially available amino group or quaternary ammonium group include DMAA (manufactured by Osaka Organic Chemical Industry Co., Ltd.), DMAEA, DMAPAA (manufactured by Kojin Co., Ltd.), and Bremer QA (Nippon Yushi Co., Ltd.). ) And New Frontier C-1615 (Daiichi Kogyo Seiyaku Co., Ltd.).

  For the polymerization reaction of the polymer, a photopolymerization reaction or a thermal polymerization reaction can be used. A photopolymerization reaction is particularly preferable. A polymerization initiator is preferably used for the polymerization reaction. For example, the above-mentioned thermal polymerization initiator and photopolymerization initiator used for forming the binder polymer of the hard coat layer may be mentioned.

  A commercially available polymerization initiator may be used as the polymerization initiator. In addition to the polymerization initiator, a polymerization accelerator may be used. The addition amount of the polymerization initiator and the polymerization accelerator is preferably in the range of 0.2 to 10% by mass of the total amount of monomers. The coating liquid (dispersion of inorganic fine particles containing monomer) may be heated to promote polymerization of the monomer (or oligomer). Moreover, it may heat after the photopolymerization reaction after application | coating, and may additionally process the thermosetting reaction of the formed polymer.

  A polymer having a relatively high refractive index is preferably used for the high refractive index layer. Examples of the polymer having a high refractive index include polystyrene, styrene copolymer, polycarbonate, melamine resin, phenol resin, epoxy resin, and polyurethane obtained by reaction of cyclic (alicyclic or aromatic) isocyanate and polyol. . Polymers having other cyclic (aromatic, heterocyclic, alicyclic) groups and polymers having halogen atoms other than fluorine as substituents can also be used with a high refractive index.

  The metal oxide layer is preferably provided by coating a coating solution containing inorganic fine particles containing a metal oxide.

  The high refractive index layer may be formed from an organometallic compound having a film forming ability.

The organometallic compound is preferably dispersible in a suitable medium or is in a liquid state. Examples of organometallic compounds include metal alcoholates (eg, titanium tetraethoxide, titanium tetra-i-propoxide, titanium tetra-n-propoxide, titanium tetra-n-butoxide, titanium tetra-sec-butoxide, titanium Tetra-tert-butoxide, aluminum triethoxide, aluminum tri-i-propoxide, aluminum tributoxide, antimony triethoxide, antimony riboxide, zirconium tetraethoxide, zirconium tetra-i-propoxide, zirconium tetra-n- Propoxide, zirconium tetra-n-butoxide, zirconium tetra-sec-butoxide, zirconium tetra-tert-butoxide), chelate compounds (eg, di-isopropoxy titanium bioxide) Acetylacetonate, di-butoxytitanium bisacetylacetonate, di-ethoxytitanium bisacetylacetonate, bisacetylacetone zirconium, aluminum acetylacetonate, aluminum di-n-butoxide monoethylacetoacetate, aluminum di-i-propoxide monomethyl Acetoacetate, tri-n-butoxide zirconium monoethyl acetoacetate), organic acid salts (for example, zirconyl ammonium carbonate), zirconium and the like.
(Low refractive index layer)
In the low refractive index layer of the optical film in the present invention, a layer lower than the refractive index of the base film is referred to as a low refractive index layer. Using a low-refractive-index layer formed by cross-linking of a fluorine-containing resin that is cross-linked by heat or ionizing radiation (hereinafter also referred to as “fluorinated resin before cross-linking”), a low-refractive index layer by a sol-gel method, and particles and a binder polymer A low refractive index layer having voids between or inside the particles is used. If the refractive index of the low refractive index layer is low, it is preferable because the antireflection performance is improved, but it is difficult from the viewpoint of imparting strength to the low refractive index layer. From this balance, the refractive index of the low refractive index layer is preferably in the range of 1.30 to 1.45. The film thickness of the low refractive index layer is preferably 5 nm to 0.5 μm, more preferably 30 nm to 0.2 μm, from the characteristics as an optical interference layer.

  A preferred example of the fluorine-containing resin before crosslinking is a fluorine-containing copolymer formed from a fluorine-containing vinyl monomer and a monomer for imparting a crosslinkable group. Specific examples of the fluorine-containing vinyl monomer unit include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3 -Dioxoles, etc.), (meth) acrylic acid partial or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (produced by Osaka Organic Chemicals) or M-2020 (produced by Daikin)), fully or partially fluorinated vinyl ethers, etc. Is mentioned. As monomers for imparting a crosslinkable group, glycidyl methacrylate, vinyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, vinyl glycidyl ether, and other vinyl monomers having a crosslinkable functional group in advance in the molecule. , Vinyl monomers having a carboxyl group, hydroxyl group, amino group, sulfonic acid group, etc. (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyalkyl vinyl ether, hydroxyalkyl allyl) Ether, etc.). The latter can introduce a crosslinked structure after copolymerization by adding a compound that reacts with a functional group in the polymer and one or more reactive groups. No. 147739. Examples of the crosslinkable group include acryloyl, methacryloyl, isocyanate, epoxy, aziridine, oxazoline, aldehyde, carbonyl, hydrazine, carboxyl, methylol, and active methylene group. When the fluorine-containing copolymer is crosslinked by heating with a crosslinking group that reacts by heating, or a combination of an ethylenically unsaturated group and a thermal radical generator or an epoxy group and a thermal acid generator, it is a thermosetting type. In the case of crosslinking by irradiation with light (preferably ultraviolet rays, electron beams, etc.) by a combination of an ethylenically unsaturated group and a photo radical generator, or an epoxy group and a photo acid generator, the ionizing radiation curable type is used.

  In addition to the above monomers, a fluorine-containing copolymer formed by using a monomer other than the fluorine-containing vinyl monomer and the monomer for imparting a crosslinkable group may be used as the fluorine-containing resin before crosslinking. The monomer that can be used in combination is not particularly limited. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, 2-acrylic acid 2- Ethyl hexyl), methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyl toluene, α-methylstyrene, etc.), vinyl ethers (methyl vinyl ether) Etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate, etc.), acrylamides (N-tertbutylacrylamide, N-cyclohexylacrylamide, etc.), methacrylamides, Ronitoriru derivatives and the like can be mentioned. In addition, it is also preferable to introduce a polyorganosiloxane skeleton or a perfluoropolyether skeleton into the fluorinated copolymer in order to impart slipperiness and antifouling properties. For example, polyorganosiloxane or perfluoropolyether having an acrylic group, methacrylic group, vinyl ether group, styryl group or the like at the terminal is polymerized with the above monomer, and polyorganosiloxane or perfluoropolyester having a radical generating group at the terminal. It can be obtained by polymerization of the above monomers with ether, reaction of a polyorganosiloxane or perfluoropolyether having a functional group with a fluorine-containing copolymer, or the like.

  The proportion of each of the above monomers used to form the fluorinated copolymer before crosslinking is preferably 20 to 70 mol%, more preferably 40 to 70 mol%, more preferably 40 to 70 mol% of the fluorinated vinyl monomer. The amount of the monomer is preferably 1 to 20 mol%, more preferably 5 to 20 mol%, and the other monomer used in combination is preferably 10 to 70 mol%, more preferably 10 to 50 mol%.

  The fluorine-containing copolymer can be obtained by polymerizing these monomers in the presence of a radical polymerization initiator by means such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization.

  The fluorine-containing resin before crosslinking is commercially available and can be used. Examples of commercially available fluorine-containing resins before cross-linking include Cytop (Asahi Glass), Teflon (registered trademark) AF (DuPont), polyvinylidene fluoride, Lumiflon (Asahi Glass), Opstar (JSR), etc. Can be mentioned.

  The low refractive index layer containing a cross-linked fluororesin as a constituent component preferably has a dynamic friction coefficient in the range of 0.03 to 0.15 and a contact angle with water in the range of 90 to 120 degrees.

  It is preferable from the viewpoint of strength improvement that the low refractive index layer containing a crosslinked fluorine-containing resin as a constituent component contains inorganic particles. As the inorganic fine particles used in the low refractive index layer, amorphous particles are preferably used, and are preferably composed of metal oxides, nitrides, sulfides or halides, and metal oxides are particularly preferable. As metal atoms, Na, K, Mg, Ca, Ba, Al, Zn, Fe, Cu, Ti, Sn, In, W, Y, Sb, Mn, Ga, V, Nb, Ta, Ag, Si, B Bi, Mo, Ce, Cd, Be, Pb and Ni are preferable, and Mg, Ca, B and Si are more preferable. Inorganic fine particles containing two or more metals may be used. Particularly preferred inorganic fine particles are silicon dioxide fine particles, that is, silica fine particles. The average particle size of the inorganic fine particles is preferably 0.001 to 0.2 μm, and more preferably 0.005 to 0.05 μm. The particle diameter of the fine particles is preferably as uniform (monodispersed) as possible. If the particle size of the inorganic fine particles is too large, light is scattered and the film becomes opaque. If the particle size is too small, the particles are likely to aggregate and difficult to synthesize and handle.

  The blending amount of the inorganic fine particles is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and particularly preferably 10 to 50% by mass with respect to the total mass of the low refractive index layer. The inorganic fine particles are preferably used after being subjected to a surface treatment. The surface treatment method includes physical surface treatment such as plasma discharge treatment and corona discharge treatment and chemical surface treatment using a coupling agent, but the use of a coupling agent is preferred. As the coupling agent, an organoalkoxy metal compound (eg, titanium coupling agent, silane coupling agent, etc.) is preferably used. When the inorganic fine particles are silica, treatment with a silane coupling agent described later is particularly effective.

  Various sol-gel materials can also be used as the material for the low refractive index layer. As such a sol-gel material, metal alcoholates (alcohols such as silane, titanium, aluminum, and zirconium), organoalkoxy metal compounds, and hydrolysates thereof can be used. In particular, alkoxysilane, organoalkoxysilane and its hydrolyzate are preferable. Examples of these include tetraalkoxysilane (tetramethoxysilane, tetraethoxysilane, etc.), alkyltrialkoxysilane (methyltrimethoxysilane, ethyltrimethoxysilane, etc.), aryltrialkoxysilane (phenyltrimethoxysilane, etc.), dialkyl. Examples thereof include dialkoxysilane and diaryl dialkoxysilane. In addition, organoalkoxysilanes having various functional groups (vinyl trialkoxysilane, methylvinyl dialkoxysilane, γ-glycidyloxypropyltrialkoxysilane, γ-glycidyloxypropylmethyl dialkoxysilane, β- (3,4-epoxy) Dicyclohexyl) ethyltrialkoxysilane, γ-methacryloyloxypropyltrialkoxysilane, γ-aminopropyltrialkoxysilane, γ-mercaptopropyltrialkoxysilane, γ-chloropropyltrialkoxysilane, etc.), perfluoroalkyl group-containing silane compounds ( For example, it is also preferable to use (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, etc.). In particular, the use of a fluorine-containing silane compound is preferable in terms of lowering the refractive index of the layer and imparting water and oil repellency.

  As the low refractive index layer, it is also preferable to use a layer formed by using inorganic or organic fine particles and forming microvoids between or within the fine particles. The average particle diameter of the fine particles is preferably 0.5 to 200 nm, more preferably 1 to 100 nm, still more preferably 3 to 70 nm, and most preferably in the range of 5 to 40 nm. The particle diameter of the fine particles is preferably as uniform (monodispersed) as possible.

  The inorganic fine particles are preferably amorphous. The inorganic fine particles are preferably made of a metal oxide, nitride, sulfide or halide, more preferably a metal oxide or a metal halide, and most preferably a metal oxide or a metal fluoride. . As metal atoms, Na, K, Mg, Ca, Ba, Al, Zn, Fe, Cu, Ti, Sn, In, W, Y, Sb, Mn, Ga, V, Nb, Ta, Ag, Si, B Bi, Mo, Ce, Cd, Be, Pb and Ni are preferable, and Mg, Ca, B and Si are more preferable. An inorganic compound containing two kinds of metals may be used. A particularly preferred inorganic compound is silicon dioxide, ie silica.

  The microvoids in the inorganic fine particles can be formed, for example, by crosslinking silica molecules forming the particles. Crosslinking silica molecules reduces the volume and makes the particles porous. (Porous) inorganic fine particles having microvoids are prepared by a sol-gel method (described in JP-A-53-112732 and JP-B-57-9051) or a precipitation method (described in APPLIED OPTICS, 27, 3356 (1988)). Can be directly synthesized as a dispersion. Further, the powder obtained by the drying / precipitation method can be mechanically pulverized to obtain a dispersion. Commercially available porous inorganic fine particles (for example, silicon dioxide sol) may be used. The inorganic fine particles having microvoids are preferably used in a state of being dispersed in an appropriate medium in order to form a low refractive index layer. As the dispersion medium, water, alcohol (for example, methanol, ethanol, isopropyl alcohol) and ketone (for example, methyl ethyl ketone, methyl isobutyl ketone) are preferable.

  The organic fine particles are also preferably amorphous. The organic fine particles are preferably polymer fine particles synthesized by polymerization reaction of monomers (for example, emulsion polymerization method). The organic fine particle polymer preferably contains a fluorine atom. The proportion of fluorine atoms in the polymer is preferably 35 to 80% by mass, and more preferably 45 to 75% by mass. It is also preferable to form microvoids in the organic fine particles by, for example, cross-linking the polymer forming the particles and reducing the volume. In order to crosslink the polymer forming the particles, it is preferable to use 20 mol% or more of the monomer for synthesizing the polymer as a polyfunctional monomer. The ratio of the polyfunctional monomer is more preferably 30 to 80 mol%, and most preferably 35 to 50 mol%. Examples of the monomer used for the synthesis of the organic fine particles include fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene) as examples of monomers containing fluorine atoms used to synthesize fluorine-containing polymers. , Perfluoro-2,2-dimethyl-1,3-dioxole), fluorinated alkyl esters of acrylic acid or methacrylic acid, and fluorinated vinyl ethers. A copolymer of a monomer containing a fluorine atom and a monomer not containing a fluorine atom may be used. Examples of monomers that do not contain fluorine atoms include olefins (eg, ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride), acrylic esters (eg, methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate). , Methacrylates (eg, methyl methacrylate, ethyl methacrylate, butyl methacrylate), styrenes (eg, styrene, vinyl toluene, α-methyl styrene), vinyl ethers (eg, methyl vinyl ether), vinyl esters ( Examples thereof include vinyl acetate and vinyl propionate), acrylamides (for example, N-tert-butylacrylamide, N-cyclohexylacrylamide), methacrylamides and acrylonitriles. Examples of polyfunctional monomers include dienes (eg, butadiene, pentadiene), esters of polyhydric alcohols and acrylic acid (eg, ethylene glycol diacrylate, 1,4-cyclohexane diacrylate, dipentaerythritol hexaacrylate), Esters of polyhydric alcohol and methacrylic acid (for example, ethylene glycol dimethacrylate, 1,2,4-cyclohexanetetramethacrylate, pentaerythritol tetramethacrylate), divinyl compounds (for example, divinylcyclohexane, 1,4-divinylbenzene), divinyl Examples include sulfones, bisacrylamides (eg, methylenebisacrylamide) and bismethacrylamides.

  Microvoids between particles can be formed by stacking at least two fine particles. When spherical particles having the same particle diameter (completely monodispersed) are closely packed, microvoids between particles with a porosity of 26% by volume are formed. When spherical fine particles having the same particle diameter are simply filled with cubic particles, microvoids between fine particles having a porosity of 48% by volume are formed. In an actual low-refractive index layer, the particle size distribution of fine particles and intra-particle microvoids exist, so the porosity varies considerably from the above theoretical value. When the porosity is increased, the refractive index of the low refractive index layer is lowered. When microvoids are formed by stacking fine particles, the size of the microvoids can be adjusted to an appropriate value (does not scatter light and cause no problem with the strength of the low refractive index layer) by adjusting the particle size of the fine particles. You can adjust. Furthermore, by making the particle diameters of the fine particles uniform, it is possible to obtain an optically uniform low refractive index layer in which the size of microvoids between particles is uniform. As a result, the low refractive index layer is microscopically a microvoided porous film, but can be made optically or macroscopically uniform. The interparticle microvoids are preferably closed in the low refractive index layer by fine particles and a polymer. The closed gap also has an advantage that light scattering on the surface of the low refractive index layer is less than that of an opening opened on the surface of the low refractive index layer.

  By forming the microvoids, the macroscopic refractive index of the low refractive index layer becomes lower than the sum of the refractive indexes of the components constituting the low refractive index layer. The refractive index of the layer is the sum of the refractive indices per volume of the layer components. The refractive index of the constituent component of the low refractive index layer such as fine particles or polymer is larger than 1, whereas the refractive index of air is 1.00. Therefore, a low refractive index layer having a very low refractive index can be obtained by forming microvoids.

The low refractive index layer preferably contains the polymer in an amount of 5 to 80% by mass. The polymer has a function of adhering fine particles and maintaining the structure of a low refractive index layer including voids. The amount of the polymer used is adjusted so that the strength of the low refractive index layer can be maintained without filling the voids. The amount of the polymer is preferably 10 to 30% by mass of the total amount of the low refractive index layer. In order to adhere the fine particles with the polymer, (1) the polymer is bonded to the surface treatment agent of the fine particles, (2) the fine particles are used as a core, and a polymer shell is formed around the fine particles. It is preferable to use a polymer as the binder. The polymer to be bonded to the surface treatment agent (1) is preferably the shell polymer (2) or the binder polymer (3). The polymer (2) is preferably formed around the fine particles by a polymerization reaction before preparing the coating solution for the low refractive index layer. The polymer (3) is preferably formed by adding a monomer to the coating solution for the low refractive index layer and performing a polymerization reaction simultaneously with or after the coating of the low refractive index layer. It is preferable to carry out a combination of two or all of the above (1) to (3), and to carry out a combination of (1) and (3) or a combination of (1) to (3). Particularly preferred. (1) Surface treatment, (2) shell, and (3) binder will be described sequentially.
(1) Surface treatment It is preferable that the fine particles (particularly inorganic fine particles) are subjected to a surface treatment to improve the affinity with the polymer. The surface treatment can be classified into physical surface treatment such as plasma discharge treatment and corona discharge treatment, and chemical surface treatment using a coupling agent. It is preferable to carry out only chemical surface treatment or a combination of physical surface treatment and chemical surface treatment. As the coupling agent, an organoalkoxy metal compound (eg, titanium coupling agent, silane coupling agent) is preferably used. When the fine particles are made of silicon dioxide, surface treatment with a silane coupling agent can be carried out particularly effectively. Specific examples of the silane coupling agent include methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxyethoxysilane, methyltriacetoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane. Methoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyltriacetoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-glycidyloxy Propyltriethoxysilane, γ- (β-glycidyloxyethoxy) propyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, Examples include N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane and β-cyanoethyltriethoxysilane.

  Examples of silane coupling agents having a disubstituted alkyl group with respect to silicon include dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyldiethoxysilane, phenylmethyldiethoxysilane, and γ-glycidyloxypropylmethyldiethoxysilane. Γ-glycidyloxypropylmethyldimethoxysilane, γ-glycidyloxypropylphenyldiethoxysilane, γ-chloropropylmethyldiethoxysilane, dimethyldiacetoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldi Ethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropylmethyldiethoxysilane, γ-mercaptopropylmethyldimeth Shishiran, .gamma.-mercaptopropyl methyl diethoxy silane, .gamma.-aminopropyl methyl dimethoxy silane, .gamma.-aminopropyl methyl diethoxy silane, methyl vinyl dimethoxy silane, and methyl vinyl diethoxy silane.

  Among these, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, γ-acryloyloxypropyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane having a double bond in the molecule. Γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, and γ-methacryloyloxypropylmethyldiethoxy having a disubstituted alkyl group with respect to silicon Silane, methylvinyldimethoxysilane and methylvinyldiethoxysilane are preferred, and γ-acryloyloxypropyltrimethoxysilane and γ-methacryloyloxyp Particularly preferred are propyltrimethoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane and γ-methacryloyloxypropylmethyldiethoxysilane.

Two or more coupling agents may be used in combination. In addition to the silane coupling agents shown above, other silane couplings may be used. Other silane coupling agents include alkyl esters of orthosilicate (eg, methyl orthosilicate, ethyl orthosilicate, n-propyl orthosilicate, i-propyl orthosilicate, n-butyl orthosilicate, sec-butyl orthosilicate, orthosilicate). Acid t-butyl) and its hydrolyzate. The surface treatment with the coupling agent can be carried out by adding the coupling agent to the fine particle dispersion and allowing the dispersion to stand at a temperature from room temperature to 60 ° C. for several hours to 10 days. In order to accelerate the surface treatment reaction, inorganic acids (for example, sulfuric acid, hydrochloric acid, nitric acid, chromic acid, hypochlorous acid, boric acid, orthosilicic acid, phosphoric acid, carbonic acid), organic acids (for example, acetic acid, polyacrylic acid, Benzenesulfonic acid, phenol, polyglutamic acid), or salts thereof (eg, metal salts, ammonium salts) may be added to the dispersion.
(2) Shell The polymer forming the shell is preferably a polymer having a saturated hydrocarbon as the main chain. A polymer containing a fluorine atom in the main chain or side chain is preferred, and a polymer containing a fluorine atom in the side chain is more preferred. Polyacrylic acid esters or polymethacrylic acid esters are preferred, and esters of fluorine-substituted alcohols with polyacrylic acid or polymethacrylic acid are most preferred. The refractive index of the shell polymer decreases as the content of fluorine atoms in the polymer increases. In order to lower the refractive index of the low refractive index layer, the shell polymer preferably contains 35 to 80% by mass of fluorine atoms, and more preferably contains 45 to 75% by mass of fluorine atoms. The polymer containing a fluorine atom is preferably synthesized by a polymerization reaction of an ethylenically unsaturated monomer containing a fluorine atom. Examples of ethylenically unsaturated monomers containing fluorine atoms include fluoroolefins (eg, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole), Examples thereof include esters of fluorinated vinyl ethers and fluorine-substituted alcohols with acrylic acid or methacrylic acid.

  The polymer forming the shell may be a copolymer composed of a repeating unit containing a fluorine atom and a repeating unit not containing a fluorine atom. The repeating unit containing no fluorine atom is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer containing no fluorine atom. Examples of ethylenically unsaturated monomers that do not contain fluorine atoms include olefins (eg, ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride), acrylic acid esters (eg, methyl acrylate, ethyl acrylate, acrylic acid 2- Ethyl hexyl), methacrylic acid esters (for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate), styrene and its derivatives (for example, styrene, divinylbenzene, vinyltoluene, α-methylstyrene), vinyl ether ( For example, methyl vinyl ether), vinyl esters (for example, vinyl acetate, vinyl propionate, vinyl cinnamate), acrylamide (for example, N-tertbutylacrylamide, N-cyclohexylacrylic) Amides), methacrylamide and acrylonitrile.

When the binder polymer (3) described later is used in combination, a crosslinkable functional group may be introduced into the shell polymer to chemically bond the shell polymer and the binder polymer by crosslinking. The shell polymer may have crystallinity. When the glass transition temperature (Tg) of the shell polymer is higher than the temperature at the time of forming the low refractive index layer, it is easy to maintain microvoids in the low refractive index layer. However, if Tg is higher than the temperature at which the low refractive index layer is formed, the fine particles are not fused, and the low refractive index layer may not be formed as a continuous layer (resulting in a decrease in strength). In that case, it is desirable to use a binder polymer (3) described later in combination, and form the low refractive index layer as a continuous layer with the binder polymer. By forming a polymer shell around the fine particles, core-shell fine particles are obtained. The core-shell fine particles preferably contain 5 to 90% by volume of a core composed of inorganic fine particles, and more preferably 15 to 80% by volume. Two or more kinds of core-shell fine particles may be used in combination. Further, inorganic fine particles having no shell and core-shell particles may be used in combination.
(3) Binder The binder polymer is preferably a polymer having a saturated hydrocarbon or polyether as the main chain, and more preferably a polymer having a saturated hydrocarbon as the main chain. The binder polymer is preferably crosslinked. The polymer having a saturated hydrocarbon as the main chain is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer. In order to obtain a crosslinked binder polymer, it is preferable to use a monomer having two or more ethylenically unsaturated groups. Examples of monomers having two or more ethylenically unsaturated groups include esters of polyhydric alcohols and (meth) acrylic acid (for example, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, pentaerythritol). Tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, Pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene and its derivatives For example, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (eg, divinyl sulfone), acrylamide (eg, methylene bisacrylamide) and methacrylamide Can be mentioned. The polymer having a polyether as the main chain is preferably synthesized by a ring-opening polymerization reaction of a polyfunctional epoxy compound. Instead of or in addition to the monomer having two or more ethylenically unsaturated groups, a crosslinked structure may be introduced into the binder polymer by the reaction of a crosslinkable group. Examples of crosslinkable functional groups include isocyanate groups, epoxy groups, aziridine groups, oxazoline groups, aldehyde groups, carbonyl groups, hydrazine groups, carboxyl groups, methylol groups, and active methylene groups. Vinylsulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane can also be used as a monomer for introducing a crosslinked structure. A functional group that exhibits crosslinkability as a result of the decomposition reaction, such as a block isocyanate group, may be used. The cross-linking group is not limited to the above compound, and may be one that exhibits reactivity as a result of decomposition of the functional group. As the polymerization initiator used for the polymerization reaction and the crosslinking reaction of the binder polymer, a thermal polymerization initiator or a photopolymerization initiator is used, and the photopolymerization initiator is more preferable. Examples of photopolymerization initiators include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds , Fluoroamine compounds and aromatic sulfoniums. Examples of acetophenones include 2,2-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxydimethylphenyl ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-4-methylthio-2-morpholinopropiophenone and 2 -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone. Examples of benzoins include benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether. Examples of benzophenones include benzophenone, 2,4-dichlorobenzophenone, 4,4-dichlorobenzophenone and p-chlorobenzophenone. Examples of phosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

The binder polymer is preferably formed by adding a monomer to the coating solution for the low refractive index layer, and at the same time as or after the coating of the low refractive index layer, by a polymerization reaction (further crosslinking reaction if necessary). Even if a small amount of polymer (for example, polyvinyl alcohol, polyoxyethylene, polymethyl methacrylate, polymethyl acrylate, diacetyl cellulose, triacetyl cellulose, nitrocellulose, polyester, alkyd resin) is added to the coating solution for the low refractive index layer Good. As a preferable optical film, an optical film having a high refractive index layer having a refractive index higher than that of the base film and a low refractive index layer having a refractive index lower than that of the base film, the high refractive index layer is: a coating solution containing a) to (c) is formed by coating, and the low refractive index layer is formed by coating a coating solution containing the following (d) and (e), and has been heat-treated. The characteristic optical film is mention | raise | lifted.
(A) Metal oxide fine particles having an average particle diameter of 10 to 200 nm (b) Metal compound (c) Ionizing radiation curable resin (d) Organosilicon compound represented by the following general formula (1) or a hydrolyzate thereof Or its polycondensate General formula (1) Si (OR) ₄
(In the formula, R is an alkyl group, preferably an alkyl group having 1 to 4 carbon atoms.)
(E) Hollow silica-based fine particles having a shell layer and porous or hollow inside <high refractive index layer>
(Metal oxide fine particles of high refractive index layer)
The high refractive index layer used in the optical film in the present invention contains metal oxide fine particles. The kind of metal oxide fine particles is not particularly limited, and Ti, Zr, Sn, Sb, Cu, Fe, Mn, Pb, Cd, As, Cr, Hg, Zn, Al, Mg, Si, P and S A metal oxide having at least one element selected from the above can be used, and these metal oxide fine particles are doped with a trace amount of atoms such as Al, In, Sn, Sb, Nb, a halogen element, and Ta. May be. A mixture of these may also be used. In the present invention, at least one metal oxide fine particle selected from among zirconium oxide, antimony oxide, tin oxide, zinc oxide, indium-tin oxide (ITO), antimony-doped tin oxide (ATO), and zinc antimonate is used. It is preferably used as a main component, and particularly preferably indium tin oxide (ITO).

  The average particle diameter of the primary particles of these metal oxide fine particles is in the range of 10 nm to 200 nm, particularly preferably 10 to 150 nm. The average particle diameter of the metal oxide fine particles can be measured from an electron micrograph taken with a scanning electron microscope (SEM) or the like. You may measure by the particle size distribution meter etc. which utilize a dynamic light scattering method, a static light scattering method, etc. If the particle size is too small, aggregation tends to occur and the dispersibility deteriorates. If the particle size is too large, the haze is remarkably increased. The shape of the metal oxide fine particles is preferably a rice grain shape, a spherical shape, a cubic shape, a spindle shape, a needle shape, or an indefinite shape.

  Specifically, the refractive index of the high refractive index layer is preferably higher than the refractive index of the base film, and is preferably in the range of 1.55 to 2.30 when measured at 23 ° C. and a wavelength of 550 nm. The means for adjusting the refractive index of the high refractive index layer is that the kind and addition amount of the metal oxide fine particles are dominant, so that the refractive index of the metal oxide fine particles is preferably 1.80 to 2.60, More preferably, it is 1.85 to 2.50.

  The metal oxide fine particles may be surface-treated with an organic compound. By modifying the surface of the metal oxide fine particles with an organic compound, the dispersion stability in an organic solvent is improved, the dispersion particle size can be easily controlled, and aggregation and sedimentation over time can be suppressed. . For this reason, the surface modification amount with a preferable organic compound is 0.1 mass%-5 mass% with respect to metal oxide particle, More preferably, it is 0.5 mass%-3 mass%. Examples of the organic compound used for the surface treatment include polyols, alkanolamines, stearic acid, silane coupling agents, and titanate coupling agents. Among these, the silane coupling agent mentioned later is preferable. Two or more kinds of surface treatments may be combined.

  The thickness of the high refractive index layer containing the metal oxide fine particles is preferably 5 nm to 1 μm, more preferably 10 nm to 0.2 μm, and most preferably 30 nm to 0.1 μm.

  The ratio of the metal oxide fine particles to be used and a binder such as ionizing radiation curable resin, which will be described later, varies depending on the type and particle size of the metal oxide fine particles, but the volume ratio of the former 1 to the latter 2 to the former 2 The latter one is preferable.

  The amount of metal oxide fine particles used in the optical film in the present invention is preferably 5% by mass to 85% by mass in the high refractive index layer, more preferably 10% by mass to 80% by mass, and more preferably 20% by mass to 75% by mass. % Is most preferred.

  The metal oxide fine particles are supplied to a coating solution for forming a high refractive index layer in a dispersion state dispersed in a medium. As a dispersion medium for metal oxide particles, it is preferable to use a liquid having a boiling point of 60 to 170 ° C. Specific examples of the dispersion solvent include water, alcohol (eg, methanol, ethanol, isopropanol, butanol, benzyl alcohol), ketone (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone), ketone alcohol (eg, diacetone alcohol). , Esters (eg, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate), aliphatic hydrocarbons (eg, hexane, cyclohexane), halogenated hydrocarbons (eg, methylene) Chloride, chloroform, carbon tetrachloride), aromatic hydrocarbons (eg, benzene, toluene, xylene), amides (eg, dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ethers (eg, diethyl ether, dioxane, Tiger hydrofuran), ether alcohols (e.g., 1-methoxy-2-propanol). Of these, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and butanol are particularly preferable.

  The metal oxide fine particles can be dispersed in the medium using a disperser. Examples of the disperser include a sand grinder mill (eg, a bead mill with pins), a high-speed impeller mill, a pebble mill, a roller mill, an attritor, and a colloid mill. A sand grinder mill and a high-speed impeller mill are particularly preferred. Further, preliminary dispersion processing may be performed. Examples of the disperser used for the preliminary dispersion treatment include a ball mill, a three-roll mill, a kneader, and an extruder.

  This optical film may further contain metal oxide fine particles having a core / shell structure. One layer of the shell may be formed around the core, or a plurality of layers may be formed in order to further improve the light resistance. The core is preferably completely covered by the shell.

  For the core, titanium oxide (rutile type, anatase type, amorphous type, etc.), zirconium oxide, zinc oxide, cerium oxide, indium oxide doped with tin, tin oxide doped with antimony, etc. can be used. Titanium may be the main component.

  The shell is preferably formed of a metal oxide or sulfide containing an inorganic compound other than titanium oxide as a main component. For example, an inorganic compound mainly composed of silicon dioxide (silica), aluminum oxide (alumina) zirconium oxide, zinc oxide, tin oxide, antimony oxide, indium oxide, iron oxide, zinc sulfide, or the like is used. Of these, alumina, silica, and zirconia (zirconium oxide) are preferable. A mixture of these may also be used.

  The coating amount of the shell with respect to the core is 2 to 50% by mass as an average coating amount. Preferably it is 3-40 mass%, More preferably, it is 4-25 mass%. When the coating amount of the shell is large, the refractive index of the fine particles is lowered, and when the coating amount is too small, the light resistance is deteriorated. Two or more inorganic fine particles may be used in combination.

The titanium oxide used as a core can use what was produced by the liquid phase method or the gaseous-phase method. As a method for forming the shell around the core, for example, U.S. Pat. No. 3,410,708, JP-B-58-47061, U.S. Pat. No. 2,885,366, and U.S. Pat. No. 1, British Patent No. 1,134,249, US Pat. No. 3,383,231, British Patent No. 2,629,953, No. 1,365,999, etc. Can do.
(Metal compound)
As the metal compound used in the optical film, a compound represented by the following general formula (2) or a chelate compound thereof can be used.

General formula (2) AnMBx-n
In the formula, M represents a metal atom, A represents a hydrolyzable functional group or a hydrocarbon group having a hydrolyzable functional group, and B represents an atomic group covalently or ionically bonded to the metal atom M. x represents the valence of the metal atom M, and n represents an integer of 2 or more and x or less.

  Examples of the hydrolyzable functional group A include halogens such as alkoxyl groups and chloro atoms, ester groups and amide groups. The metal compound belonging to the above formula (2) includes an alkoxide having two or more alkoxyl groups bonded directly to a metal atom, or a chelate compound thereof. Preferable metal compounds include titanium alkoxide, zirconium alkoxide, or chelate compounds thereof. Titanium alkoxide has a high reaction rate and a high refractive index and is easy to handle. However, since it has a photocatalytic action, its light resistance deteriorates when added in a large amount. Zirconium alkoxide has a high refractive index but tends to become cloudy, so care must be taken in dew point management during coating. In addition, since titanium alkoxide has an effect of accelerating the reaction between the ultraviolet curable resin and the metal alkoxide, the physical properties of the functional film can be improved by adding a small amount.

  Examples of the titanium alkoxide include tetramethoxy titanium, tetraethoxy titanium, tetra-iso-propoxy titanium, tetra-n-propoxy titanium, tetra-n-butoxy titanium, tetra-sec-butoxy titanium, tetra-tert-butoxy titanium, and the like. Is mentioned.

  Examples of the zirconium alkoxide include tetramethoxy zirconium, tetraethoxy zirconium, tetra-iso-propoxy zirconium, tetra-n-propoxy zirconium, tetra-n-butoxy zirconium, tetra-sec-butoxy zirconium, tetra-tert-butoxy zirconium and the like. Is mentioned.

  Preferred chelating agents for coordination with free metal compounds to form chelate compounds include alkanolamines such as diethanolamine and triethanolamine, glycols such as ethylene glycol, diethylene glycol and propylene glycol, acetylacetone and acetoacetate Examples thereof include ethyl and the like having a molecular weight of 10,000 or less. By using these chelating agents, it is possible to form a chelate compound that is stable against moisture mixing and is excellent in the effect of reinforcing the functional membrane.

The addition amount of the metal compound is preferably adjusted so that the content of the metal oxide derived from the metal compound contained in the high refractive index layer is 0.3 to 5% by mass. If it is less than 0.3% by mass, the scratch resistance is insufficient, and if it exceeds 5% by mass, the light resistance tends to deteriorate.
(Ionizing radiation curable resin)
The ionizing radiation curable resin is added as a binder for the metal oxide fine particles to improve the film formability and physical properties of the functional film. As the ionizing radiation curable resin, a monomer or oligomer having two or more functional groups that cause polymerization reaction directly by irradiation of ionizing radiation such as ultraviolet rays or electron beams or indirectly by the action of a photopolymerization initiator is used. Can be used. Examples of the functional group include a group having an unsaturated double bond such as a (meth) acryloyloxy group, an epoxy group, and a silanol group. Among these, radically polymerizable monomers and oligomers having two or more unsaturated double bonds can be preferably used. You may combine a photoinitiator as needed. Examples of such ionizing radiation curable resins include polyfunctional acrylate compounds and the like, and the group consisting of pentaerythritol polyfunctional acrylate, dipentaerythritol polyfunctional acrylate, pentaerythritol polyfunctional methacrylate, and dipentaerythritol polyfunctional methacrylate. It is preferable that it is a compound chosen from these. Here, the polyfunctional acrylate compound is a compound having two or more acryloyloxy groups and / or methacryloyloxy groups in the molecule.

  Examples of the monomer of the polyfunctional acrylate compound include ethylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, and tetramethylolmethanetriacrylate. Acrylate, tetramethylolmethane tetraacrylate, pentaglycerol triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, glycerin triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, Dipen Erythritol hexaacrylate, tris (acryloyloxyethyl) isocyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, tetra Methylol methane trimethacrylate, tetramethylol methane tetramethacrylate, pentaglycerol trimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerin trimethacrylate, dipentaerythritol trimethacrylate, dipentaerythritol te La methacrylate, dipentaerythritol penta methacrylate, dipentaerythritol hexa methacrylate preferred. These compounds are used alone or in admixture of two or more. Moreover, oligomers, such as a dimer and a trimer of the said monomer, may be sufficient.

  The addition amount of the ionizing radiation curable resin is preferably 15% by mass or more and less than 50% by mass in the solid content in the high refractive index composition.

  In order to accelerate the curing of the ionizing radiation curable resin, a photopolymerization initiator and an acrylic compound having two or more polymerizable unsaturated bonds in the molecule are contained in a mass ratio of 3: 7 to 1: 9. Is preferred.

Specific examples of the photopolymerization initiator include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof, but are not particularly limited thereto.
(solvent)
Examples of the organic solvent used for coating the high refractive index layer include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexane). Hexanol, benzyl alcohol, etc.), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, Thiodiglycol, etc.), polyhydric alcohol ethers (for example, ethylene glycol monomethyl ether) Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl Ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.), amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine) Ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.) Heterocycles (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides (for example, dimethyl sulfoxide, etc.), Examples include sulfones (for example, sulfolane), urea, acetonitrile, acetone, and the like, and alcohols, polyhydric alcohols, and polyhydric alcohol ethers are particularly preferable.
<Low refractive index layer>
The refractive index of the low refractive index layer used in this optical film is lower than the refractive index of the base film, and is preferably in the range of 1.30 to 1.45 when measured at 23 ° C. and a wavelength of 550 nm.

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

  The composition for forming a low refractive index layer used in this optical film comprises (d) an organosilicon compound represented by the following general formula (3) or a hydrolyzate thereof or a polycondensate thereof, and (e) an outer shell layer. Hollow silica-based fine particles having a porous or hollow interior are essential components.

General formula (3) Si (OR) ₄
(In the formula, R is an alkyl group, preferably an alkyl group having 1 to 4 carbon atoms.)
In addition, a silane coupling agent, a curing agent, a surfactant and the like may be added as necessary.
[Hollow silica fine particles]
The hollow silica-based fine particles having the outer shell layer represented by (e) and having a porous or hollow interior will be described.

  The hollow silica-based fine particles are (I) composite particles comprising porous particles and a coating layer provided on the surface of the porous particles, or (II) having cavities inside, and the contents are solvent, gas or porous It is a hollow particle filled with a porous material. Note that the low refractive index layer only needs to contain either (I) composite particles or (II) hollow particles, or both.

  The hollow particles are particles having cavities inside, and the cavities are surrounded by particle walls. The cavity is filled with contents such as a solvent, a gas, or a porous material used at the time of preparation. It is desirable that the average particle size of such hollow fine particles is in the range of 5 to 300 nm, preferably 10 to 200 nm. The average particle diameter of the hollow fine particles used is appropriately selected according to the thickness of the transparent film to be formed, and is in the range of 2/3 to 1/10 of the film thickness of the transparent film such as the low refractive index layer to be formed. It is desirable to be in These hollow fine particles are preferably used in a state of being dispersed in an appropriate medium in order to form a low refractive index layer. As the dispersion medium, water, alcohol (for example, methanol, ethanol, isopropyl alcohol), ketone (for example, methyl ethyl ketone, methyl isobutyl ketone), and ketone alcohol (for example, diacetone alcohol) are preferable.

  The thickness of the coating layer of the composite particles or the thickness of the particle walls of the hollow particles is desirably in the range of 1 to 20 nm, preferably 2 to 15 nm. In the case of composite particles, if the thickness of the coating layer is less than 1 nm, the particles may not be completely covered, and it is easy to use a silicate monomer or oligomer having a low polymerization degree, which is a coating liquid component described later. The inside of the composite particles may enter and the internal porosity may decrease, and the low refractive index effect may not be sufficiently obtained. When the thickness of the coating layer exceeds 20 nm, the silicic acid monomer and oligomer do not enter the inside, but the porosity (pore volume) of the composite particles is lowered and the effect of low refractive index is sufficiently obtained. It may not be possible. In the case of hollow particles, if the particle wall thickness is less than 1 nm, the particle shape may not be maintained, and even if the thickness exceeds 20 nm, the effect of low refractive index may not be sufficiently exhibited. .

The coating layer of the composite particles or the particle wall of the hollow particles is preferably composed mainly of silica. In addition, components other than silica may be contained. Specifically, Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , CeO ₂ , P ₂ O ₃ , Sb ₂ O ₃ , MoO ₃ , ZnO ₂ , WO _{3 and the} like. Examples of the porous particles constituting the composite particles include those made of silica, those made of silica and an inorganic compound other than silica, and those made of CaF ₂ , NaF, NaAlF ₆ , MgF, and the like. Of these, porous particles made of a composite oxide of silica and an inorganic compound other than silica are particularly suitable. Examples of inorganic compounds other than silica include Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , CeO ₂ , P ₂ O ₃ , Sb ₂ O ₃ , MoO ₃ , ZnO ₂ , WO _{3 and the} like. 1 type or 2 types or more can be mentioned. In such porous particles, the molar ratio MOX / SiO ₂ when the silica is represented by SiO ₂ and the inorganic compound other than silica is represented by oxide (MOX) is 0.0001 to 1.0, preferably It is desirable to be in the range of 0.001 to 0.3. It is difficult to obtain a porous particle having a molar ratio MO _X / SiO ₂ of less than 0.0001. Even if it is obtained, particles having a small pore volume and a low refractive index cannot be obtained. In addition, when the molar ratio MO _X / SiO _{2 of} the porous particles exceeds 1.0, the ratio of silica decreases, so that the pore volume increases and it is difficult to obtain a low refractive index. is there.

  The pore volume of such porous particles is desirably in the range of 0.1 to 1.5 ml / g, preferably 0.2 to 1.5 ml / g. If the pore volume is less than 0.1 ml / g, particles having a sufficiently reduced refractive index cannot be obtained. If the pore volume exceeds 1.5 ml / g, the strength of the fine particles is lowered, and the strength of the resulting coating may be lowered. is there.

  In addition, the pore volume of such porous particles can be determined by a mercury intrusion method. Examples of the contents of the hollow particles include a solvent, a gas, and a porous substance used at the time of preparing the particles. The solvent may contain an unreacted particle precursor used when preparing the hollow particles, the catalyst used, and the like. Examples of the porous substance include those composed of the compounds exemplified for the porous particles. These contents may be composed of a single component or may be a mixture of a plurality of components.

  As a method for producing such hollow fine particles, for example, the method for preparing composite oxide colloidal particles disclosed in paragraphs [0010] to [0033] of JP-A-7-133105 is suitably employed. Specifically, when the composite particles are composed of silica and an inorganic compound other than silica, hollow fine particles are produced from the following first to third steps.

First Step: Preparation of Porous Particle Precursor In the first step, an alkali aqueous solution of a silica raw material and an inorganic compound raw material other than silica is separately prepared in advance, or a silica raw material and an inorganic compound raw material other than silica are prepared in advance. A mixed aqueous solution is prepared, and this aqueous solution is gradually added to an aqueous alkaline solution having a pH of 10 or more while stirring according to the composite ratio of the target composite oxide to prepare a porous particle precursor.

  As the silica raw material, alkali metal, ammonium or organic base silicate is used. Sodium silicate (water glass) or potassium silicate is used as the alkali metal silicate. Examples of the organic base include quaternary ammonium salts such as tetraethylammonium salt, and amines such as monoethanolamine, diethanolamine, and triethanolamine. The ammonium silicate or the organic base silicate includes an alkaline solution obtained by adding ammonia, a quaternary ammonium hydroxide, an amine compound or the like to a silicic acid solution.

  In addition, alkali-soluble inorganic compounds are used as raw materials for inorganic compounds other than silica. Specifically, an oxo acid of an element selected from Al, B, Ti, Zr, Sn, Ce, P, Sb, Mo, Zn, W, etc., an alkali metal salt or alkaline earth metal salt of the oxo acid, ammonium And salts and quaternary ammonium salts. More specifically, sodium aluminate, sodium tetraborate, zirconyl ammonium carbonate, potassium antimonate, potassium stannate, sodium aluminosilicate, sodium molybdate, cerium ammonium nitrate, and sodium phosphate are suitable.

Although the pH value of the mixed aqueous solution changes simultaneously with the addition of these aqueous solutions, an operation for controlling the pH value within a predetermined range is not particularly required. The aqueous solution finally has a pH value determined by the type of inorganic oxide and the mixing ratio thereof. There is no restriction | limiting in particular in the addition rate of the aqueous solution at this time. Further, in the production of composite oxide particles, a dispersion of seed particles can be used as a starting material. The seed particles are not particularly limited, but inorganic oxides such as SiO ₂ , Al ₂ O ₃ , TiO ₂ or ZrO ₂ or fine particles of these composite oxides are used. Usually, these sols can be used. . Furthermore, the porous particle precursor dispersion obtained by the above production method may be used as a seed particle dispersion. When using a seed particle dispersion, the pH of the seed particle dispersion is adjusted to 10 or higher, and then an aqueous solution of the compound is added to the above-mentioned alkaline aqueous solution while stirring. Also in this case, it is not always necessary to control the pH of the dispersion. When seed particles are used in this way, it is easy to control the particle size of the porous particles to be prepared, and particles with uniform particle sizes can be obtained.

  The silica raw material and the inorganic compound raw material described above have high solubility on the alkali side. However, when both are mixed in this highly soluble pH region, the solubility of oxo acid ions such as silicate ions and aluminate ions decreases, and these composites precipitate and grow into fine particles, or seed particles. It grows on the top and particle growth occurs. Therefore, it is not always necessary to perform pH control as in the conventional method for precipitation and growth of fine particles.

The composite ratio of the silica and the inorganic compound other than silica in the first step is calculated by converting the inorganic compound to silica into an oxide (MO _X ), and the molar ratio of MO _X / SiO ₂ is 0.05 to 2.0, Preferably it is in the range of 0.2-2.0. Within this range, the pore volume of the porous particles increases as the silica proportion decreases. However, even when the molar ratio exceeds 2.0, the pore volume of the porous particles hardly increases. On the other hand, when the molar ratio is less than 0.05, the pore volume becomes small. When preparing the hollow particles, the molar ratio of MO _X / SiO ₂ is desirably in the range of 0.25 to 2.0.

Second step: Removal of inorganic compound other than silica from porous particles In the second step, inorganic compounds other than silica (elements other than silicon and oxygen) are obtained from the porous particle precursor obtained in the first step. At least a portion is selectively removed. As a specific removal method, the inorganic compound in the porous particle precursor is dissolved and removed using a mineral acid or an organic acid, or is contacted with a cation exchange resin for ion exchange removal.

  The porous particle precursor obtained in the first step is a particle having a network structure in which silicon and an inorganic compound constituent element are bonded through oxygen. By removing the inorganic compound (elements other than silicon and oxygen) from the porous particle precursor in this way, porous particles having a larger porosity and a larger pore volume can be obtained. Further, if the amount of removing the inorganic oxide (elements other than silicon and oxygen) from the porous particle precursor is increased, the hollow particles can be prepared.

  In addition, prior to removing inorganic compounds other than silica from the porous particle precursor, fluorine-substituted, obtained by dealkalizing an alkali metal salt of silica into the porous particle precursor dispersion obtained in the first step. It is preferable to add a silicic acid solution containing an alkyl group-containing silane compound or a hydrolyzable organosilicon compound to form a silica protective film. The thickness of the silica protective film may be 0.5 to 15 nm. Even if the silica protective film is formed, the protective film in this step is porous and thin, so that it is possible to remove inorganic compounds other than silica described above from the porous particle precursor.

  By forming such a silica protective film, inorganic compounds other than silica described above can be removed from the porous particle precursor while maintaining the particle shape. Further, when forming the silica coating layer described later, the pores of the porous particles are not blocked by the coating layer, and therefore the silica coating layer described later is formed without reducing the pore volume. Can do. Note that when the amount of the inorganic compound to be removed is small, the particles are not broken, and thus it is not always necessary to form a protective film.

  When preparing hollow particles, it is desirable to form this silica protective film. When preparing the hollow particles, the inorganic compound is removed to obtain a hollow particle precursor composed of a silica protective film, a solvent in the silica protective film, and an undissolved porous solid content. When a coating layer to be described later is formed on the precursor, the formed coating layer becomes a particle wall to form hollow particles.

The amount of the silica source added for forming the silica protective film is preferably small as long as the particle shape can be maintained. If the amount of the silica source is too large, the silica protective film becomes too thick, and it may be difficult to remove inorganic compounds other than silica from the porous particle precursor. Examples of hydrolyzable organosilicon compounds used for forming a silica protective film include general formula RnSi (OR ′) ₄ -n [R, R ′: hydrocarbon such as alkyl group, aryl group, vinyl group, acrylic group, etc. An alkoxysilane represented by the group, n = 0, 1, 2, or 3] can be used. In particular, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane substituted with fluorine are preferably used.

  As an addition method, a solution obtained by adding a small amount of alkali or acid as a catalyst to a mixed solution of these alkoxysilane, pure water, and alcohol is added to the dispersion of the porous particles, and the alkoxysilane is hydrolyzed. The produced silicic acid polymer is deposited on the surface of the inorganic oxide particles. At this time, alkoxysilane, alcohol, and catalyst may be simultaneously added to the dispersion. As the alkali catalyst, ammonia, an alkali metal hydroxide, or an amine can be used. As the acid catalyst, various inorganic acids and organic acids can be used.

  When the dispersion medium of the porous particle precursor is water alone or when the ratio of water to the organic solvent is high, a silica protective film can be formed using a silicic acid solution. When a silicic acid solution is used, a predetermined amount of the silicic acid solution is added to the dispersion, and at the same time an alkali is added to deposit the silicic acid solution on the surface of the porous particles. In addition, you may produce a silica protective film together using a silicic acid liquid and the said alkoxysilane.

Third step: Formation of silica coating layer In the third step, the porous particle dispersion prepared in the second step (in the case of hollow particles, the hollow particle precursor dispersion) contains a fluorine-substituted alkyl group-containing silane compound. By adding a hydrolyzable organosilicon compound or silicic acid solution, the surface of the particles is coated with a polymer such as a hydrolyzable organosilicon compound or silicic acid solution to form a silica coating layer.

Examples of the hydrolyzable organosilicon compound used for forming the silica coating layer include the general formula RnSi (OR ′) ₄ -n [R, R ′: alkyl group, aryl group, vinyl group, acrylic group as described above. Etc., and alkoxysilanes represented by n = 0, 1, 2, or 3] can be used. In particular, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane are preferably used.

  As an addition method, a solution obtained by adding a small amount of alkali or acid as a catalyst to a mixed solution of these alkoxysilane, pure water, and alcohol is used as a dispersion of the porous particles (in the case of hollow particles, a hollow particle precursor). In addition, the silicic acid polymer produced by hydrolyzing alkoxysilane is deposited on the surface of the porous particles (in the case of hollow particles, hollow particle precursors). At this time, alkoxysilane, alcohol, and catalyst may be simultaneously added to the dispersion. As the alkali catalyst, ammonia, an alkali metal hydroxide, or an amine can be used. As the acid catalyst, various inorganic acids and organic acids can be used.

  When the dispersion medium of porous particles (in the case of hollow particles, the hollow particle precursor) is water alone or a mixed solvent with an organic solvent and the mixed solvent has a high ratio of water to the organic solvent, a silicate solution You may form a coating layer using. The silicic acid solution is an aqueous solution of a low silicic acid polymer obtained by dealkalizing an aqueous solution of an alkali metal silicate such as water glass by ion exchange treatment.

  The silicic acid solution is added to the dispersion of porous particles (in the case of hollow particles, hollow particle precursors), and at the same time, alkali is added to make the low-silicic acid polymer into porous particles (in the case of hollow particles, hollow particle precursors). ) Deposit on the surface. In addition, you may use a silicic acid liquid for the coating layer formation in combination with the said alkoxysilane. The addition amount of the organosilicon compound or silicic acid solution used for forming the coating layer only needs to be sufficient to cover the surface of the colloidal particles, and the finally obtained silica coating layer has a thickness of 1 to 20 nm. In such an amount, it is added in a dispersion of porous particles (in the case of hollow particles, hollow particle precursor) in a dispersion. When the silica protective film is formed, the organosilicon compound or the silicate solution is added in such an amount that the total thickness of the silica protective film and the silica coating layer is in the range of 1 to 20 nm.

  Next, the dispersion liquid of the particles on which the coating layer is formed is heat-treated. By the heat treatment, in the case of porous particles, the silica coating layer covering the surface of the porous particles is densified, and a dispersion of composite particles in which the porous particles are coated with the silica coating layer is obtained. In the case of a hollow particle precursor, the formed coating layer is densified to form hollow particle walls, and a dispersion of hollow particles having cavities filled with a solvent, gas, or porous solid content is obtained.

  The heat treatment temperature at this time is not particularly limited as long as it can close the fine pores of the silica coating layer, and is preferably in the range of 80 to 300 ° C. When the heat treatment temperature is less than 80 ° C., the fine pores of the silica coating layer may not be completely closed and densified, and the treatment time may take a long time. Further, when the heat treatment temperature exceeds 300 ° C. for a long time, fine particles may be formed, and the effect of low refractive index may not be obtained.

  The refractive index of the inorganic fine particles thus obtained is as low as less than 1.42. Such inorganic fine particles are presumed to have a low refractive index because the porosity inside the porous particles is maintained or the inside is hollow.

  The content of the hollow silica-based fine particles having an outer shell layer and porous or hollow inside is preferably 10 to 50% by mass. In order to obtain the effect of a low refractive index, the content is preferably 15% by mass or more, and when it exceeds 50% by mass, the binder component is decreased and the film strength becomes insufficient. Most preferably, it is 20-50 mass%.

  In the organic silicon compound represented by the general formula (3), R represents an alkyl group having 1 to 4 carbon atoms.

  Specifically, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane are preferably used.

  As a method of adding to the low refractive index layer, a solution obtained by adding a small amount of alkali or acid as a catalyst to a mixed solution of these tetraalkoxysilane, pure water, and alcohol is added to the dispersion of the hollow silica fine particles. The silicic acid polymer produced by hydrolyzing tetraalkoxysilane is deposited on the surface of the hollow silica fine particles. At this time, tetraalkoxysilane, alcohol, and catalyst may be simultaneously added to the dispersion. As the alkali catalyst, ammonia, an alkali metal hydroxide, or an amine can be used. As the acid catalyst, various inorganic acids and organic acids can be used.

  The low refractive index layer may contain a fluorine-substituted alkyl group-containing silane compound represented by the following general formula (4).

  The fluorine-substituted alkyl group-containing silane compound represented by the general formula (4) will be described.

In the formula, R ^{1 to} R ⁶ are alkyl groups having 1 to 16 carbon atoms, preferably 1 to 4 carbon atoms, halogenated alkyl groups having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, 6 to 12 carbon atoms, preferably 6 carbon atoms. 10 to 10 aryl groups, 7 to 14 carbon atoms, preferably 7 to 12 alkylaryl groups, arylalkyl groups, 2 to 8 carbon atoms, preferably 2 to 6 alkenyl groups, or 1 to 6 carbon atoms, preferably 1 to 3 alkoxy groups, a hydrogen atom or a halogen atom.

Rf represents-(CaHbFc)-, a is an integer of 1 to 12, b + c is 2a, b is an integer of 0 to 24, and c is an integer of 0 to 24. Such Rf is preferably a group having a fluoroalkylene group and an alkylene group. Specifically, as such a fluorine-containing silicone compound, (MeO) ₃ SiC ₂ H ₄ C ₂ F ₄ C ₂ H ₄ Si (MeO) ₃ , (MeO) ₃ SiC ₂ H ₄ C ₄ F ₈ C ₂ H ₄ Si (MeO) ₃ , (MeO) ₃ SiC ₂ H ₄ C ₆ F ₁₂ C ₂ H ₄ Si (MeO) ₃ , (H ₅ C ₂ O) ₃ SiC ₂ H ₄ C ₄ F ₈ C ₂ H Examples include methoxydisilane compounds represented by ₄ Si (OC ₂ H ₅ ) ₃ , (H ₅ C ₂ O) ₃ SiC ₂ H ₄ C ₆ F ₁₂ C ₂ H ₄ Si (OC ₂ H ₅ ) ₃ , and the like.

  If the fluorine-containing alkyl group-containing silane compound is included as a binder, the transparent film itself is hydrophobic, so the transparent film is not sufficiently densified and is porous or cracked. Even if it has a void or a void, entry into the transparent film by chemicals such as moisture, acid and alkali is suppressed. Furthermore, fine particles such as metals contained in the conductive layer which is the surface of the base material or the lower layer do not react with chemicals such as moisture, acid and alkali. For this reason, such a transparent film has excellent chemical resistance.

  In addition, when a fluorine-substituted alkyl group-containing silane compound is included as a binder, not only the hydrophobic property but also the slipperiness (low contact resistance) is obtained, and thus a transparent film having excellent scratch strength can be obtained. Can do. Furthermore, when the binder contains a fluorine-substituted alkyl group-containing silane compound having such a structural unit, when the conductive layer is formed in the lower layer, the shrinkage of the binder is equal to or close to that of the conductive layer. Since it is a thing, the transparent film excellent in adhesiveness with the conductive layer can be formed. Furthermore, when the transparent film is heat-treated, the conductive layer is not peeled off due to the difference in shrinkage rate, and a portion having no electrical contact is not generated in the transparent conductive layer. For this reason, sufficient electroconductivity can be maintained as a whole film.

  A transparent film containing a fluorine-substituted alkyl group-containing silane compound and hollow silica-based fine particles having the outer shell layer and being porous or hollow inside has high scratch strength and is evaluated by eraser strength or nail strength. The film strength is high, the pencil hardness is high, and a transparent film excellent in strength can be formed.

  The low refractive index layer may contain a silane coupling agent. Silane coupling agents include methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxyethoxysilane, methyltriacetoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane. Ethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyltri Acetoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-glycidyloxypropyltri Ethoxysilane, γ- (β-glycidyloxyethoxy) propyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, γ- Acryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, N- Examples include β- (aminoethyl) -γ-aminopropyltrimethoxysilane and β-cyanoethyltriethoxysilane.

  Examples of silane coupling agents having a disubstituted alkyl group with respect to silicon include dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyldiethoxysilane, phenylmethyldiethoxysilane, and γ-glycidyloxypropylmethyldiethoxysilane. Γ-glycidyloxypropylmethyldimethoxysilane, γ-glycidyloxypropylphenyldiethoxysilane, γ-chloropropylmethyldiethoxysilane, dimethyldiacetoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldi Ethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropylmethyldiethoxysilane, γ-mercaptopropylmethyldimeth Shishiran, .gamma.-mercaptopropyl methyl diethoxy silane, .gamma.-aminopropyl methyl dimethoxy silane, .gamma.-aminopropyl methyl diethoxy silane, methyl vinyl dimethoxy silane, and methyl vinyl diethoxy silane.

  Among these, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, γ-acryloyloxypropyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane having a double bond in the molecule. Γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, and γ-methacryloyloxypropylmethyldiethoxy having a disubstituted alkyl group with respect to silicon Silane, methylvinyldimethoxysilane and methylvinyldiethoxysilane are preferred, and γ-acryloyloxypropyltrimethoxysilane and γ-methacryloyloxyp Particularly preferred are propyltrimethoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane and γ-methacryloyloxypropylmethyldiethoxysilane.

  Two or more coupling agents may be used in combination. In addition to the silane coupling agents shown above, other silane coupling agents may be used. Other silane coupling agents include alkyl esters of orthosilicate (eg, methyl orthosilicate, ethyl orthosilicate, n-propyl orthosilicate, i-propyl orthosilicate, n-butyl orthosilicate, sec-butyl orthosilicate, orthosilicate). Acid t-butyl) and its hydrolyzate.

  Examples of the polymer used as the other binder of the low refractive index layer include polyvinyl alcohol, polyoxyethylene, polymethyl methacrylate, polymethyl acrylate, diacetyl cellulose, triacetyl cellulose, nitrocellulose, polyester, and alkyd resin.

The low refractive index layer preferably contains 5 to 80% by mass of binder as a whole. The binder has a function of adhering the hollow silica fine particles and maintaining the structure of the low refractive index layer including voids. The usage-amount of a binder is adjusted so that the intensity | strength of a low refractive index layer can be maintained, without filling a space | gap.
(solvent)
The coating composition for the low refractive index layer preferably contains an organic solvent. Specific examples of organic solvents include alcohols (eg, methanol, ethanol, isopropanol, butanol, benzyl alcohol), ketones (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone), esters (eg, methyl acetate, ethyl acetate). , Propyl acetate, butyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate), aliphatic hydrocarbons (eg, hexane, cyclohexane), halogenated hydrocarbons (eg, methylene chloride, chloroform, carbon tetrachloride), aromatic Group hydrocarbon (eg, benzene, toluene, xylene), amide (eg, dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ether (eg, diethyl ether, dioxane, tetrahydrofuran), ether alcohol (eg, 1-methoxy-2-propanol). Of these, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and butanol are particularly preferable.

The solid content concentration in the low refractive index layer coating composition is preferably 1 to 4% by mass. By making the solid content concentration 4% by mass or less, coating unevenness is less likely to occur, and the content is 1% by mass or more. By doing so, the drying load is reduced.
(Fluorosurfactant, silicone oil or silicone surfactant)
It is preferable that the hard coat layer, the high refractive index layer, and the low refractive index layer contain a fluorine-based surfactant, a silicone oil, or a silicone-based surfactant. Inclusion of the surfactant is effective for reducing coating unevenness and improving the antifouling property of the film surface.

  Fluorosurfactants include perfluoroalkyl group-containing monomers, oligomers, and polymers as the core, and include derivatives such as polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, and polyoxyethylene. It is done.

  Commercially available products may be used as the fluorosurfactant, for example, Surflon “S-381”, “S-382”, “SC-101”, “SC-102”, “SC-103”, “SC-104”. (All manufactured by Asahi Glass Co., Ltd.), Florard “FC-430”, “FC-431”, “FC-173” (all manufactured by Fluorochemical-Sumitomo 3M), Ftop “EF352”, “EF301”, “EF303” (both manufactured by Shin-Akita Kasei Co., Ltd.), Schwego Fluer “8035”, “8036” (both manufactured by Schwegman), “BM1000”, “BM1100” (all manufactured by BM Himmy) , MegaFuck “F-171”, “F-470” (both manufactured by Dainippon Ink & Chemicals, Inc.), and the like.

  The fluorine content of the fluorosurfactant is 0.05 to 2%, preferably 0.1 to 1%. The above-mentioned fluorosurfactants can be used alone or in combination of two or more, and can be used in combination with other surfactants.

  The silicone oil or silicone surfactant will be described.

  Silicone oils can be broadly classified into straight silicone oils and modified silicone oils depending on the type of organic group bonded to silicon atoms. Straight silicone oil refers to those bonded with a methyl group, a phenyl group, or a hydrogen atom as a substituent. A modified silicone oil is one having a component that is secondarily derived from a straight silicone oil.

  On the other hand, it can be classified from the reactivity of silicone oil. These are summarized as follows.

Silicone oil Straight silicone oil 1-1. Non-reactive silicone oil: dimethyl, methylphenyl substitution, etc. 1-2. Reactive silicone oil: methyl hydrogen substitution, etc. Modified silicone oil Modified silicone oil was born by introducing various organic groups into dimethyl silicone oil 2-1. Non-reactive silicone oil: Alkyl, alkyl / aralkyl, alkyl / polyether, polyether, higher fatty acid ester substitution, etc. Alkyl / aralkyl-modified silicone oil is a part of the methyl group of dimethyl silicone oil with a long chain alkyl group or phenyl Silicone oils substituted with alkyl groups, polyether-modified silicone oils are silicone-based polymer surfactants in which hydrophilic polyoxyalkylene is introduced into hydrophobic dimethyl silicone, and higher fatty acid-modified silicone oils are methyl methyl dimethyl silicone oil. Silicone oils and amino-modified silicone oils in which part of the groups are replaced with higher fatty acid esters are silicone oils and epoxy-modified silicones that have a structure in which some of the methyl groups in the silicone oil are replaced with aminoalkyl groups. The silicone oil has a structure in which a part of the methyl group of the silicone oil is replaced with an epoxy group-containing alkyl group. The carboxyl-modified or alcohol-modified silicone oil has a structure in which a part of the methyl group of the silicone oil is a carboxyl group- or hydroxyl group-containing alkyl. Silicone oil having a structure substituted with a group 2-2. Reactive silicone oil: amino, epoxy, carboxyl, alcohol substitution, etc. Of these, polyether-modified silicone oil is preferably added. The number average molecular weight of the polyether-modified silicone oil is, for example, 1,000 to 100,000, preferably 2,000 to 50,000. When the number average molecular weight is less than 1,000, the functional film is dried. On the other hand, if the number average molecular weight exceeds 100,000, it tends to be difficult to bleed out on the functional film surface.

  As specific products, Nippon Unicar Co., Ltd. L-45, L-9300, FZ-3704, FZ-3703, FZ-3720, FZ-3786, FZ-3501, FZ-3504, FZ-3508, FZ-3705, FZ-3707, FZ-3710, FZ-3750, FZ-3760, FZ-3785, FZ-3785, Y-7499, Shin-Etsu Chemical KF96L, KF96, KF96H, KF99, KF54, KF965, KF968, KF56, KF995, KF351, KF352, KF353, KF354, KF355, KF615, KF618, KF945, KF6004, FL100, and the like.

  The silicone surfactant preferably used is a surfactant in which a part of the methyl group of the silicone oil is substituted with a hydrophilic group. The position of substitution includes a side chain of silicone oil, both ends, one end, both end side chains, and the like. Examples of the hydrophilic group include polyether, polyglycerin, pyrrolidone, betaine, sulfate, phosphate, and quaternary salt.

  As the silicone surfactant, a nonionic surfactant having a hydrophobic group composed of dimethylpolysiloxane and a hydrophilic group composed of polyoxyalkylene is preferable.

  A nonionic surfactant is a generic term for surfactants that do not have a group capable of dissociating into ions in an aqueous solution. Oxyethylene) or the like as a hydrophilic group. Hydrophilicity increases as the number of alcoholic hydroxyl groups increases and as the polyoxyalkylene chain (polyoxyethylene chain) becomes longer. The nonionic surfactant preferably used is characterized by having dimethylpolysiloxane as a hydrophobic group.

  When a nonionic surfactant composed of a dimethylpolysiloxane having a hydrophobic group and a polyoxyalkylene having a hydrophilic group is used, the unevenness of the low refractive index layer and the antifouling property of the film surface are improved. It is considered that the hydrophobic group made of polymethylsiloxane is oriented on the surface to form a film surface that is not easily soiled. This effect cannot be obtained by using other surfactants.

  Specific examples of these nonionic surfactants include, for example, Nippon Unicar Co., Ltd., silicone surfactants SILWET L-77, L-720, L-7001, L-7002, L-7604, Y-7006, FZ-2101, FZ-2104, FZ-2105, FZ-2110, FZ-2118, FZ-2120, FZ-2122, FZ-2123, FZ-2130, FZ-2154, FZ-2161, FZ-2162, FZ- 2163, FZ-2164, FZ-2166, FZ-2191 and the like.

  Moreover, SUPERSILWET SS-2801, SS-2802, SS-2803, SS-2804, SS-2805, etc. are mentioned.

  Further, as a preferable structure of the nonionic surfactant in which the hydrophobic group is composed of dimethylpolysiloxane and the hydrophilic group is composed of polyoxyalkylene, the dimethylpolysiloxane structure portion and the polyoxyalkylene chain are alternately and repeatedly bonded. It is preferably a linear block copolymer. Since the main chain skeleton has a long chain length and a linear structure, it is excellent. This is considered to be due to the fact that one activator molecule can be adsorbed on the surface of the silica fine particle at a plurality of locations so as to cover the surface of the silica fine particle by being a block copolymer in which hydrophilic groups and hydrophobic groups are alternately repeated.

  Specific examples thereof include, for example, silicone surfactants ABN SILWET FZ-2203, FZ-2207, FZ-2208 and the like manufactured by Nippon Unicar Co., Ltd.

  Among these silicone oils or silicone surfactants, those having a polyether group are preferred.

  Other surfactants may also be used in combination. For example, anionic surfactants such as sulfonates, sulfates, phosphates, etc., and ethers having polyoxyethylene chain hydrophilic groups Type, ether ester type nonionic surfactants and the like may be used in combination.

  These silicone oils or silicone surfactants are preferably used in the low refractive index layer and the layer adjacent to the low refractive index layer, specifically, the hard coat layer and the high refractive index layer. When the low refractive index layer is the outermost surface layer of the optical film, it not only improves the water repellency, oil repellency and antifouling property of the functional film, but also exhibits an effect on the surface scratch resistance. The content in the coating solution for the high refractive index layer and the low refractive index layer is preferably 0.05 to 2.0% by mass. If it is less than 0.05% by mass, the crack resistance effect is insufficient, and if it exceeds 2.0% by mass, uneven coating occurs.

In addition to the above-mentioned components (inorganic fine particles, polymer, dispersion medium, polymerization initiator, polymerization accelerator), the coating liquid for each layer of the functional film formation described above includes a polymerization inhibitor, a leveling agent, a thickener, and a coloring inhibitor. Further, an ultraviolet absorber, a silane coupling agent, an antistatic agent or an adhesion promoter may be added. Each layer of the optical film can be formed by coating by dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, or extrusion coating (US Pat. No. 2,681,294). I can do it. Two or more layers may be applied simultaneously. For the method of simultaneous application, US Pat. Nos. 2,761,791, 2,941,898, 3,508,947, 3,526,528 and Yuji Harasaki, Coating Engineering, page 253, It is described in Asakura Shoten (1973).
(Back coat layer)
In the optical film used in the present invention, particles having a particle diameter of 0.01 to 1 μm are 0.02 to 10.00 with respect to the entire coating liquid on the film surface side opposite to the surface on which the functional film is applied. It is preferable to provide a backcoat layer coated with a coating solution containing mass%. The content is more preferably 0.05% by mass to 5.00% by mass, and still more preferably 0.08% by mass to 2.00% by mass. The larger the addition amount, the lower the dynamic friction coefficient, and the smaller the addition amount, the lower the haze and the fewer the aggregates.

  Examples of the particles included in the back coat layer useful in the present invention include inorganic compound fine particles and organic compound fine particles.

  As fine particles added to the back coat layer, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, tin oxide, and oxidation. Mention may be made of indium, zinc oxide, ITO, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable from the viewpoint of reducing haze, and silicon dioxide is particularly preferable.

  These fine particles are commercially available under the trade names of, for example, Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.). . Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used. Examples of the polymer include silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large anti-blocking effect while keeping haze low. The optical film used in the present invention preferably has a dynamic friction coefficient on the back side of the hard coat layer of 0.9 or less, particularly 0.1 to 0.9.

  The organic solvent used in the back coat layer is not particularly limited, but since the anti-curl function can be imparted to the back coat layer, the organic solvent that dissolves the cellulose ester film and the resin of the cellulose ester film material or the organic solvent that swells. Solvents are useful. These may be appropriately selected depending on the curl degree of the cellulose ester film, the type of resin, the mixing ratio, the coating amount, and the like.

  Examples of the organic solvent that can be used for the backcoat layer include benzene, toluene, xylene, dioxane, acetone, methyl ethyl ketone, N, N-dimethylformamide, methyl acetate, ethyl acetate, N-methylpyrrolidone, 1,3-dimethyl- 2-Imidazolidinone.

  Examples of the organic solvent that is not dissolved include methanol, ethanol, n-propyl alcohol, i-propyl alcohol, and n-butanol, but the organic solvent is not particularly limited thereto.

  As a coating method of the backcoat layer coating composition, the coating liquid film thickness (sometimes referred to as wet film thickness) is 1 to 100 μm using a gravure coater, dip coater, wire bar coater, reverse coater, extrusion coater, etc. In particular, 5 to 30 μm is preferable.

  Examples of the resin used as the binder for the back coat layer include vinyl chloride / vinyl acetate copolymer, vinyl chloride resin, vinyl acetate resin, vinyl acetate / vinyl alcohol copolymer, partially hydrolyzed vinyl chloride / vinyl acetate copolymer. Vinyl homopolymers or copolymers such as vinyl chloride / vinylidene chloride copolymer, vinyl chloride / acrylonitrile copolymer, ethylene / vinyl alcohol copolymer, chlorinated polyvinyl chloride, ethylene / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, cellulose nitrate, Cellulose ester-based resins such as cellulose acetate propionate, cellulose diacetate, cellulose triacetate, cellulose acetate phthalate, cellulose acetate butyrate resin, male Copolymers of acid and / or acrylic acid, acrylate copolymers, acrylonitrile / styrene copolymers, chlorinated polyethylene, acrylonitrile / chlorinated polyethylene / styrene copolymers, methyl methacrylate / butadiene / styrene copolymers, acrylic resins, polyvinyl acetal resins, polyvinyl butyral Resin, polyester polyurethane resin, polyether polyurethane resin, polycarbonate polyurethane resin, polyester resin, polyether resin, polyamide resin, amino resin, rubber resin such as styrene / butadiene resin, butadiene / acrylonitrile resin, silicone resin, fluorine resin , Polymethyl methacrylate, copolymers of polymethyl methacrylate and polymethyl acrylate, etc. Door but can be, but is not limited to these. Particularly preferred are cellulose resin layers such as cellulose diacetate and cellulose acetate propionate.

The order of coating the back coat layer may be before or after the hard coat layer of the cellulose ester film is coated, but when the back coat layer also serves as an anti-blocking layer, it is preferably coated first. Alternatively, the backcoat layer can be applied in two or more steps.
(Configuration of optical film)
Although the structure of a preferable optical film is shown below, it is not limited to these.

  Here, the hard coat layer means the actinic radiation curable resin layer described above.

Base film / hard coat layer / high refractive index layer / low refractive index layer Base film / hard coat layer / high refractive index layer Base film / antistatic layer / hard coat layer / high refractive index layer / low refractive index layer Base film / Anti-glare hard coat layer / High refractive index layer / Low refractive index layer Base film / Antistatic layer / Anti-glare hard coat layer / High refractive index layer / Low refractive index layer The back coat layer described above is preferably provided on the side opposite to the side on which the functional film is applied.

  In the present invention, after the hard coat layer is formed, the surface of the hard coat layer is subjected to surface treatment, and the high refractive index layer and the low refractive index layer according to the present invention are formed on the surface of the hard coat layer subjected to the surface treatment. It is preferable.

  Examples of the surface treatment include cleaning methods, alkali treatment methods, flame plasma treatment methods, high frequency discharge plasma methods, electron beam methods, ion beam methods, sputtering methods, acid treatments, corona treatment methods, atmospheric pressure glow discharge plasma methods, and the like. The alkali treatment method and the corona treatment method are preferable, and the alkali treatment method is particularly effective.

  The reflectance of the optical film according to the present invention can be measured with a spectrophotometer. At that time, after the surface on the measurement side of the sample is roughened, the light absorption treatment is performed using a black spray, and then the reflected light in the visible light region (400 to 700 nm) is measured. The reflectance is preferably as low as possible, but the average value in the visible light wavelength is preferably 1.5% or less, and the minimum reflectance is preferably 0.8% or less. Moreover, it is preferable to have a flat reflection spectrum in the wavelength region of visible light.

  In addition, the reflection hue on the surface of the polarizing plate that has undergone antireflection treatment is often colored red or blue due to the high reflectance in the short wavelength region and long wavelength region in the visible light region due to the design of the antireflection film. The color tone of the reflected light varies depending on the application, and when used on the outermost surface of an FPD television or the like, a neutral color tone is desired. In this case, generally preferred reflection hue ranges are 0.17 ≦ x ≦ 0.27 and 0.07 ≦ y ≦ 0.17 on the XYZ color system (CIE1931 color system).

  The film thicknesses of the high refractive index layer and the low refractive index layer can be obtained by calculation according to a conventional method in consideration of the reflectance and the color of reflected light based on the refractive index of each layer.

As described above, the functional layer and the back coat layer are applied to the base film and dried. Further, a knurling process having a desired knurling height is performed at a predetermined timing, and in the winding process, the film is wound into a roll shape, and an optical film can be manufactured through a heat treatment. As a method of winding in a roll shape, a generally used method may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like. .
(Polarizer)
The optical film obtained by the production method of the present invention can be applied to a polarizing plate.

  The polarizing plate can be produced by a general method. The back surface side of the optical film of the present invention is subjected to alkali saponification treatment, and a completely saponified alcohol aqueous solution is provided on at least one surface of a polarizing film (PVA or modified PVA) produced by immersing and stretching the treated optical film in an iodine solution. It is preferable to stick together. As the polarizing film, a polarizing film having a thickness of 5 to 30 μm, preferably 10 to 25 μm is preferably used.

  The optical film may be used on the other surface, or another polarizing plate protective film may be used. The polarizing plate protective film used on the other surface of the optical film of the present invention preferably has an in-plane retardation Ro of 590 nm, a phase difference of 20 to 200 nm, and Rt of 100 to 400 nm. . These can be created by the method described in Japanese Patent Application Laid-Open No. 2002-71957 and Japanese Patent Application No. 2002-155395, for example.

  Alternatively, it is preferable to use a polarizing plate protective film that also serves as an optical compensation film having an optically anisotropic layer formed by aligning a liquid crystal compound such as a discotic liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP-A-2003-98348. By using in combination with the optical film of the present invention, a polarizing plate having excellent flatness and a stable viewing angle expansion effect can be obtained.

  As the polarizing plate protective film used on the back side, KC8UX2MW, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5 (manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used.

  The polarizing film, which is the main component of the polarizing plate, is an element that transmits only light having a polarization plane in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol film. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed. As the polarizing film, a polyvinyl alcohol aqueous solution is formed and dyed by uniaxially stretching or dyed, or uniaxially stretched after dyeing, and then preferably subjected to a durability treatment with a boron compound. On the surface of the polarizing film, one side of the optical film of the present invention is bonded to form a polarizing plate. It is preferably bonded with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like.

  For example, polarizing films described in JP-A-2004-20633, JP-A-2004-20629, JP-A-2004-184574, JP-A-2003-268127, JP-A-2003-248123, and JP-A-2000-121829 are preferably used. The thickness of the polarizing film is preferably 5 to 30 μm.

The polarizing plate using the conventional optical film is inferior in flatness, and when the reflected image is seen, fine wavy unevenness is recognized, and the wavy unevenness is increased by the durability test under the conditions of 60 ° C. and 90% RH. On the other hand, the polarizing plate using the optical film of the present invention was excellent in flatness. In addition, even in a durability test under the conditions of 60 ° C. and 90% RH, the wavy unevenness does not increase, and even with a polarizing plate having an optical compensation film on the back surface side, the viewing angle characteristics after the durability test are It was possible to provide good visibility without fluctuation.
(Display device)
By incorporating the polarizing plate into a display device, various display devices with excellent visibility can be manufactured. The optical film of the present invention is preferably a reflective, transmissive, transflective LCD, or TN, STN, OCB, HAN, VA (PVA, MVA), IPS, or other driving LCD. Used. Further, the optical film of the present invention has remarkably little unevenness of the reflected light of the antireflection layer, and has excellent flatness, and various display devices such as a plasma display, a field emission display, an organic EL display, an inorganic EL display, and electronic paper Also preferably used. In particular, a large-screen display device with a 30-inch screen or more has the effect that there is little unevenness in color and undulation, and eyes are not tired even during long-time viewing.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, the embodiment of this invention is not limited to these.
(Examples 1-37, Comparative Examples 1-7)
A cellulose ester film was prepared as a base film by the method described below.

A back coat layer is provided on one side (back side) of this base film, and the hard coat layer is continuously provided on the opposite side (front side) without winding up, and then the following antireflection layer is hard coated. Painted on top of the layer. The knurling process was performed at a predetermined timing, and the wound film was heat-treated in the form of a roll. 1-44 were obtained. The knurling process was performed by pressing a heated embossing roll, and a desired knurling height was obtained by changing the embossing roll temperature and pressing pressure. The process will be described in detail below.
(Preparation of base film)
<Preparation of dope solution>
The following materials were sequentially put into a sealed container, and the temperature in the container was raised from 18 ° C. to 85 ° C., and then stirred for 3 hours while maintaining the temperature at 85 ° C. to completely dissolve the cellulose ester. . The silicon oxide fine particles were added dispersed in a solution of a solvent to be added in advance and a small amount of cellulose ester. This dope was filtered twice using a filter paper (Azumi filter paper No. 244, manufactured by Azumi Filter Paper Co., Ltd.) to obtain a dope.
(Preparation of dope solution)
Cellulose ester (cellulose triacetate; acetyl group substitution degree 2.9)
100 parts by mass Trimethylolpropane tribenzoate 5.5 parts by mass Ethylphthalyl ethyl glycolate 4.5 parts by mass Methylene chloride 300 parts by mass Ethanol 40 parts by mass Silicon oxide fine particles (Aerosil R972V (produced by Nippon Aerosil Co., Ltd.))
0.2 parts by mass The dope prepared as described above was cast on a 35 ° C. support made of a stainless steel endless belt through a casting die kept at 35 ° C. to form a web. And dried on the support until the residual solvent amount of the web reached 75% by mass, and then the web was peeled from the support with a peeling roll.

  Next, the web is dried with a drying air at 70 ° C. in a conveying and drying process using a plurality of rolls arranged on the top and bottom, and then grips both ends of the web with a tenter, and then is stretched in the width direction at 130 ° C. 1.1 times before stretching. It extended | stretched so that it might become. After stretching with a tenter, the web is dried with a drying air at 120 ° C. in a conveying and drying process using a plurality of rolls arranged at the top and bottom, dried to a residual solvent amount of 0.1% by mass, and then rolled before winding. Both ends of the hand are slit processed, the substrate width is 2000 mm, and the film is wound with the thickness and winding length shown in Tables 1 and 2, respectively. 1-44 were made and it was set as the base film. The draw ratio in the web conveyance direction immediately after peeling calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.1 times. The film thickness was adjusted by the dope amount cast on the stainless steel belt.

The prepared cellulose ester film was measured in the width direction by the transmitted light measurement mode of a transmission type infrared film thickness meter (Kurabo Industries RX-100 type), and the local film thickness deviation of the base film was measured. The cellulose ester film No. having the characteristic values described in Tables 1 and 2 was measured. 1-44 were used respectively.
(Preparation of back coat layer)
The following back coat layer composition was applied to one surface (back surface) of each of the above base films with an extrusion coater so as to have a wet film thickness of 10 μm, and dried at 85 ° C. to provide a back coat layer. .
<Backcoat layer composition>
Acetone 54 parts by weight Methyl ethyl ketone 24 parts by weight Methanol 22 parts by weight Diacetylcellulose 0.6 part by weight Ultrafine silica 2% acetone dispersion (used as MAT agent)
(Japan Aerosil Co., Ltd. Aerosil 200V)
Table 1 and Table 2 show the MAT agent primary particle size (μm) and the MAT agent content of the particle size of the ultrafine silica particles that are particles contained in the coating solution applied to the back surface of the substrate and the content of the particles with respect to the entire coating solution. It prepared so that it might become quantity (mass%).

Further, the following hard coat layer coating solution is filtered through a polypropylene filter having a pore diameter of 0.4 μm to prepare a hard coat layer coating solution, which is applied to the other surface (surface) and dried at 90 ° C. The functional film was cured using an ultraviolet lamp with an illuminance of the irradiated part of 100 mW / cm ² and an irradiation amount of 0.1 J / cm ² to form a hard coat layer with a predetermined film thickness.
(Preparation of hard coat layer)
The following materials were stirred and mixed to obtain a hard coat layer coating solution.

Acrylic monomer; KAYARAD DPHA (dipentaerythritol hexaacrylate, Nippon Kayaku) 225 parts by mass Irgacure 184 (manufactured by Ciba Specialty Chemicals) 20 parts by mass Propylene glycol monomethyl ether 110 parts by mass Ethyl acetate 110 parts by mass (antireflection layer) Production)
On the hard coat layer prepared above, a high refractive index layer and then a low refractive index layer were provided as described below, and an antireflection layer having a multilayer structure was coated thereon. In the single-layer configuration, a low refractive index layer is coated on the hard coat layer to form an antireflection layer. In this way, Nos. 1 and 2 in Tables 1 and 2 were used. 1 to 44 optical films were prepared.
(Preparation of antireflection layer: high refractive index layer)
On the hard coat layer, the following high refractive index layer coating composition is applied by an extrusion coater, dried at 50 ° C. for 1 minute, and then cured by irradiation with ultraviolet rays of 0.1 J / cm ² to a thickness of 130 nm. Thus, a high refractive index layer was provided. The refractive index of this high refractive index layer was 1.56.
<High refractive index layer coating composition>
Zinc antimonate sol 60 parts by mass (CX-Z610M-F2, manufactured by Nissan Chemical Industries, Ltd.)
8 parts by mass of methoxypolyethylene glycol # 1000 acrylate (NK-ester AM-230G, manufactured by Shin-Nakamura Chemical Co., Ltd.)
4 parts by mass of pentaerythritol tetraacrylate (NK-ester A-TMMT, manufactured by Shin-Nakamura Chemical Co., Ltd.)
1-hydroxy-cyclohexyl phenyl ketone 2 parts by mass (Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.)
3-Methacryloyloxypropyltrimethoxysilane 3 parts by mass (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.)
2 parts by mass of 10% propylene glycol monomethyl ether solution of polyoxyalkylenedimethylpolysiloxane copolymer (FZ-2207, manufactured by Toray Dow Corning Co., Ltd.)
Propylene glycol monomethyl ether 360 parts by mass Isopropyl alcohol 360 parts by mass Methyl ethyl ketone 200 parts by mass (Preparation of antireflection layer: low refractive index layer)
On the above-mentioned high refractive index layer, the following low refractive index layer coating composition was applied by an extrusion coater so that the thickness after drying was 80 nm, dried at 50 ° C. for 1 minute, and then irradiated with UV rays at a concentration of 0.1%. The film was cured by irradiation with 1 J / cm ² , further heat-cured at 120 ° C. for 1 minute, and then wound up.

At this time, by controlling the content of the hollow silica fine particles, the local film thickness deviation in the width direction of the functional film formation after coating and drying was set to the values shown in Tables 1 and 2.
(Preparation of low refractive index layer coating composition)
<Preparation of tetraethoxysilane hydrolyzate>
A hydrolyzate was prepared by mixing 230 g of tetraethoxysilane and 440 g of ethanol, adding 120 g of a 2% aqueous acetic acid solution, and stirring in a water bath at 25 ° C. for 20 hours.

Tetraethoxysilane hydrolyzate 90 parts by mass Hollow silica-based fine particles (P-2 below) Predetermined parts KBM503 (silane coupling agent, manufactured by Shin-Etsu Chemical Co., Ltd.) 3 parts by mass 10% isopropyl alcohol solution of carbino-modified silicone resin 0 .6 parts by mass (KF-6003, manufactured by Shin-Etsu Chemical Co., Ltd.)
6 parts by mass of 10% isopropyl alcohol solution of aluminum ethyl acetoacetate diisopropylate (ALCH, manufactured by Kawaken Fine Chemical Co., Ltd.)
α-Butyl-ω- [3- (2,2-bis (hydroxymethyl) butoxy) propyl] polydimethylsiloxane 10% isopropyl alcohol solution 2 parts by mass (Silaplane FM-DA21, manufactured by Chisso Corporation)
Propylene glycol monomethyl ether 450 parts by mass Isopropyl alcohol 450 parts by mass <Preparation of hollow silica-based fine particles P-2>
A mixture of 100 g of silica sol having an average particle diameter of 5 nm and a SiO ₂ concentration of 20% by mass and 1900 g of pure water was heated to 80 ° C. The pH of the reaction mother liquor is 10.5, uterine solution added as SiO ₂ as a 0.98 wt% aqueous solution of sodium silicate 9000g and Al ₂ O ₃ of 1.02% by weight sodium aluminate solution 9000g simultaneously did. Meanwhile, the temperature of the reaction solution was kept at 80 ° C. The pH of the reaction solution rose to 12.5 immediately after the addition and hardly changed thereafter. After completion of the addition, the reaction solution was cooled to room temperature and washed with an ultrafiltration membrane to prepare a SiO ₂ .Al ₂ O ₃ core particle dispersion having a solid content concentration of 20% by mass.

1700 g of pure water is added to 500 g of this core particle dispersion and heated to 98 ° C., and while maintaining this temperature, a silicic acid solution (SiO ₂₎ obtained by dealkalizing a sodium silicate aqueous solution with a cation exchange resin. A dispersion of core particles in which 3000 g (concentration of 3.5% by mass) was added to form a first silica coating layer was obtained.

Next, 1125 g of pure water is added to 500 g of the core particle dispersion liquid that has been washed with an ultrafiltration membrane to form a first silica coating layer having a solid concentration of 13% by mass, and concentrated hydrochloric acid (35.5%) is further added dropwise. The pH was adjusted to 1.0 and dealumination was performed. Next, the aluminum salt dissolved in the ultrafiltration membrane was separated while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water, and SiO ₂ · Al from which some of the constituent components of the core particles forming the first silica coating layer were removed. A dispersion of ₂ O ₃ porous particles was prepared.

A mixture of 1500 g of the above porous particle dispersion, 500 g of pure water, 1,750 g of ethanol, and 626 g of 28% ammonia water is heated to 35 ° C., and then 104 g of ethyl silicate (SiO ₂ 28 mass%) is added. The surface of the porous particles on which the first silica coating layer was formed was coated with a hydrolyzed polycondensate of ethyl silicate to form a second silica coating layer. Subsequently, a dispersion of hollow silica-based fine particles (P-2) having a solid content concentration of 20% by mass in which the solvent was replaced with ethanol using an ultrafiltration membrane was prepared.

The thickness of the first silica coating layer of the hollow silica-based fine particles was 3 nm, the average particle size was 45 nm, MOx / SiO ₂ (molar ratio) was 0.0017, and the refractive index was 1.28. Here, the average particle diameter was measured by a dynamic light scattering method. Thus, each optical film provided with a hard coat layer and an antireflection layer was prepared. The refractive index of this low refractive index layer was 1.37.

  In addition, using the same method as that for measuring the local film thickness deviation of the base film, the local film thickness deviation in the width direction of the functional film after drying for each film (at this time, Table 1 and Table 2 show the results of measuring the local film thickness deviation in the width direction of the film including the base film and the functional film after coating.

Also, the configuration of the cellulose ester film, the antireflection layer, and the height and position of the knurling part produced by pressing a heated embossing roll on the film end were changed as shown in Tables 1 and 2, respectively. In Examples 1 to 37 and Comparative Examples 1 to 7, the optical film Nos. 1-44 were made. The height of the knurling part at that time was adjusted so that a desired height could be obtained by changing the embossing roll temperature and the pressing pressure.
(Optical film winding and heat treatment)
The optical film produced as described above is wound around a plastic winding core having a diameter of 200 mm with the tensions shown in Tables 1 and 2, and then the heating conditions in Tables 1 and 2 as the heating conditions are as follows. Retained.
(Blocking, black band evaluation)
The optical film Nos. 1 to 37 and Comparative Examples 1 to 7 prepared as described above were used. 1 to 44 were visually evaluated from the wound state for the occurrence of blocking and black bands according to the following criteria.
(Blocking evaluation criteria)
Blocking after heat treatment ◎: No generation, little core transfer ○: No generation, but core transfer ○ △: Very weak generation △: Weak generation ×: Strong generation (user claim level)
(Black band (BB) evaluation criteria)
Black band after heat treatment ◎: No generation, little core transfer ○: No generation, but core transfer ○ △: Very weak generation △: Weak generation ×: Strong generation (user claim level)
The evaluation level is a usable level if it is Δ or more.

  The results are shown in Tables 1 and 2.

  In the results of Tables 1 and 2, when Examples 1 to 7 and Comparative Examples 1 to 7 are compared, in the optical film having a local film thickness deviation of 0.2 to 2.5 μm, the knurling height is 14 to 30 μm. By doing, it turns out that the blocking after heat processing and a black band are favorable results. Moreover, when Example 4 and Examples 8-12 are compared, as for the film thickness of a base film, the thing of 35 micrometers-100 micrometers is preferable that generation | occurrence | production of the blocking after a heat processing and a black band is suppressed, More preferably, it is 40 micrometers-80 micrometers. It can be seen that it is. Moreover, when Example 13 and Example 14 are compared, it can be said that the local film thickness deviation of the base film is preferably 2.0 μm or less because blocking and black band generation after heat treatment are suppressed. Furthermore, when Example 4 and Example 15 are compared, it can be said that the local film thickness deviation of the functional film after drying is preferably 0.5 μm or less because blocking and black band generation after heat treatment are suppressed. Further, when Example 10 and Examples 16 to 21 are compared, a coating film containing 0.02 to 10.00 mass% of particles having a particle size of 0.01 to 1 μm with respect to the entire coating liquid is used as the base film. It can be seen that it is preferable to apply the functional film to the back surface of the surface on which the functional film is applied because blocking and black band generation after the heat treatment are suppressed. In addition, when Example 2 and Example 22 are compared, the knurling treatment is performed on the outer side in the width direction of the region where the functional film is applied in the base film, thereby suppressing the occurrence of blocking and black bands after the heat treatment. It turns out that it is preferable. Moreover, when Example 2 and Examples 23-26 are compared, it is preferable that the tension | tensile_strength at the time of winding in a winding process is 30-400 N / m because generation | occurrence | production of the blocking after heat processing and a black band is suppressed. Recognize. Moreover, when Example 2 and Example 27 and Example 28 are compared, it turns out that the film winding length in a winding process is 4000 m or less, and generation | occurrence | production of the blocking after heat processing and a black band is suppressed. Moreover, when Example 2 and Examples 29-36 are compared, after the winding process, it is possible to perform a heat treatment for holding the wound roll film at a temperature of 50 to 150 ° C. for 3 to 30 days. It can be seen that blocking and black band generation are suppressed and preferable. Moreover, when Example 4 and Example 37 are compared, it can be seen that the functional film has the same result for both a single layer and a multilayer.

It is the schematic of the knurling part which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st knurling part 2 2nd knurling part 3 Hard coat layer 4 Antireflection layer F Base film H Width of knurling part

Claims (13)

A coating step of applying a functional film on the surface of a continuously moving film, a knurling step of knurling the film, a drying step of drying the film coated with the functional film, and after the drying step In a method for producing an optical film, including a winding step of winding the film,
The local film thickness deviation in the width direction of the film after the drying step is 0.2 to 2.5 μm,
The said knurling process is processed to the surface side which apply | coats the functional film of the said film, and knurling height is 14-30 micrometers, The manufacturing method of the optical film characterized by the above-mentioned. The method for producing an optical film according to claim 1, wherein the film thickness before the coating step is 35 to 100 μm. The method for producing an optical film according to claim 1, wherein a local film thickness deviation in the width direction of the film before the coating step is 0.1 to 2.0 μm. The method for producing an optical film according to any one of claims 1 to 3, wherein a local film thickness deviation in the width direction of the functional film after the drying step is 0.1 to 0.5 µm. A coating liquid containing 0.02 to 10.00 mass% of particles having a volume average particle size of 0.01 to 1 μm is applied to the surface of the film opposite to the surface to which the functional film is applied. The method for producing an optical film according to any one of claims 1 to 4. The optical film manufacturing method according to any one of claims 1 to 5, wherein the knurling treatment is performed on an outer side in a width direction of a region of the film to which the functional film is applied. The method for producing an optical film according to any one of claims 1 to 6, wherein a tension during winding in the winding step is 30 to 400 N / m. The method for producing an optical film according to any one of claims 1 to 7, wherein a winding length of the film in the winding step is 500 to 4000 m. The method for producing an optical film according to any one of claims 1 to 8, wherein the film has a width of 1000 to 4000 mm. The method for producing an optical film according to any one of claims 1 to 9, wherein after the winding step, the wound film is held at a temperature of 50 to 150 ° C for 3 to 30 days. An optical film produced by the method for producing an optical film according to any one of claims 1 to 10. A polarizing plate using the optical film according to claim 11. A liquid crystal display device using the polarizing plate according to claim 12.

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