JP4479260B2 - Manufacturing method of optical film - Google Patents

Description

  The present invention relates to a method for producing an optical film comprising a plastic film substrate, and more particularly to a method for producing an optical film having a functional layer on the surface of a long-rolled plastic film substrate wound up in a roll shape.

  In addition to the CRT, various display devices such as a liquid crystal television, a plasma display (PDP), and an organic EL display have been developed, 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. In addition, such a large-screen display device is easily scratched because it may be directly touched by hands or touched by objects. Therefore, an antireflection film with a hard coat layer in which a hard coat layer is usually formed on a support for preventing scratches and an antireflection layer or the like is formed thereon has been used.

  As the antireflection film, a wide film having a width of 1 mm or more, and further 1.4 m or more has been particularly required due to the enlargement of the screen. However, when the width is increased due to the increase in size as described above, uneven color and periodic unevenness occur in reflection performance, coloring degree, phase difference performance, visual field expansion performance, etc. There is a need for a highly uniform optical film that is free from differences between the outside and inside the winding, between the center and the end in the width direction, and between lots. Moreover, the film without a winding deformation | transformation is calculated | required from a viewpoint of handling in a manufacturing process.

  Conventionally, when handling long rolls of plastic film, it is possible to tighten the roll wound around the core or to store it at the time of storage by providing portions that are bulkier than the film surface called knurling or embossing on both sides of the film. A method for preventing folding or the like from occurring is known (see, for example, Patent Documents 1 and 2).

  On the other hand, various optical films having various functional thin films on a long-rolled plastic film substrate are known. After forming a functional thin film on the substrate, a short film is used to improve the strength of the thin film. In order to obtain a certain strength over time, it is known to perform a heat treatment called curing or aging (see, for example, Patent Documents 3 and 4). It is described that an optical film having a high surface hardness can be obtained by performing a heat treatment at 40 to 150 ° C. for 30 minutes or more and several weeks in a state of being wound into a back roll.

However, in these conventional techniques, there is no description that an optical film with high uniformity without color unevenness can be obtained by applying these techniques to the production of a wide optical film, Therefore, it has been strongly desired to provide a method for producing an optical film with high uniformity that does not cause winding deformation or color unevenness, and has a small difference between lots or a difference between roll unwinding and winding.
Japanese Patent Laid-Open No. 2002- 211803 Japanese Patent No. 3226190 JP 2001-91705 A JP 2002-6104 A

  Accordingly, an object of the present invention is a highly uniform optical film that does not cause winding deformation or color unevenness. In particular, the difference between lots, the difference between unwinding and winding of a roll, and the center and end in the width direction. It is an object of the present invention to provide a method for producing an optical film having a higher uniformity and a smaller difference from the part.

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

(Claim 1)
In the method for producing an optical film having a hard coat layer or a hard coat layer and a functional layer on a transparent plastic film substrate having at least one knurling portion in the film winding direction, the hard coat layer or the hard coat layer and the function A method for producing an optical film, wherein a heated embossing roll is pressed onto the knurling portion and the knurling portion is processed in an overlapping manner after the step of applying the adhesive layer.

(Claim 2)
The method for producing an optical film according to claim 1, characterized in that the knurling portion processed Na-ring part total thickness in the overlapping range of 5 μm~30μm.

(Claim 3)
After applying a hard coat layer or a hard coat layer and a functional layer on a transparent plastic film substrate having at least one knurling part in the film winding direction, the heated embossing roll is pressed onto the knurling part to overlap. The optical film processed in the knurling part is wound into a roll shape, and is heated to 42 ° C. for 3 days or more in the state of being wound in a roll shape. A method for producing an optical film, comprising heating at a rate of temperature increase of -30 ° C / day.

(Claim 4)
The method for producing an optical film according to claim 3, wherein the total thickness of the knurling portions that are processed by overlapping knurling is set to a range of 5 μm to 30 μm.

(Claim 5)
5. The method for producing an optical film according to claim 3, wherein the heat treatment is performed at a treatment temperature of 50 to 120 ° C. for a period of 3 to 30 days.

(Claim 6)
When the optical film is wound into a roll, the total thickness of the knurling part on the winding core side is thicker than the total thickness of the knurling part on the outside of the winding, and the difference in thickness is in the range of 1 μm to 10 μm. The manufacturing method of the optical film of any one of Claims 1-5.

(Claim 7)
2. The transparent plastic film substrate is at least one selected from cellulose ester resin, polyester resin, polycarbonate resin, polyethersulfone resin, polyacrylate resin, norbornene resin, and acrylic styrene resin. The manufacturing method of the optical film of any one of -6.

(Claim 8)
The functional layer is a layer that contains at least one of a metal oxide, a metal oxynitride, a metal nitride, an organic polymer, and a liquid crystal compound and imparts an antireflection function. The manufacturing method of the optical film of any one of these.

  According to the present invention, it is an optical film having high uniformity without occurrence of winding deformation and color unevenness, and in particular, difference between lots, difference between roll unwinding and winding, center and end in width direction. It is possible to provide a method for producing an optical film with higher uniformity and a smaller difference.

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

(Knurling part and knurling part processing)
First, the knurling part and knurling part processing according to the present invention will be described with reference to the drawings. However, the figure is an example, and the present invention is not limited to this.

  FIG. 1 is a schematic view of a knurling portion according to the present invention.

In the present invention, in the manufacturing method of an optical film having at least one hard coat layer on a transparent plastic film substrate having a Na-ring unit or the hard coat layer and the functional layer to the film winding direction, the hard coat layer or After the step of applying the hard coat layer and the functional layer, a heated embossing roll is pressed onto the knurling part to overlap and process the knurling part. That is, it is characterized in that a knurling portion is provided in an overlapping manner before winding after film formation and before winding after coating a hard coat layer or a hard coat layer and a functional layer.

The knurling part of the present invention is a film made thicker than the film substrate surface by providing a thick film or an uneven band in the winding direction of the transparent plastic film substrate. Usually, it is preferable to make it bulky as an uneven band having a high anti-blocking effect, which is likely to occur when a roll-shaped film is wound. 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 .

  As a method of providing unevenness as a knurling portion, 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 film at Tg + 20 ° C. or higher and 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 thickness of the knurling part according to the present invention refers to the thickness from the film surface to the embossed convex part, and the embossing roll is engraved with irregularities so that the height of the convex part becomes a desired height at the stage of processing of the embossing roll. This is achieved by using

  The width 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. Although the position of a knurling part is not specifically limited, It is preferable that the embossing is given to the part of 0-50 mm from the film edge part.

  At the time of manufacturing the transparent plastic film, for example, the first knurling portion 1 is provided by applying the embossing rolls to both ends of the film, and the hard coat layer 3 or the hard coat layer 3 and the antireflection layer 4 which is a functional layer described later are provided. The second knurling part 2 is provided on the first knurling part after the optical functional layer including it is coated. The knurling part is formed using an embossing roll heated before winding the transparent plastic film substrate, and the second knurling part is similarly provided using an embossing roll heated before winding after coating the optical functional layer. Just do it.

In the present invention, it is necessary to press the embossing roll which heated the 2nd knurling part on the 1st knurling part, and to process a knurling part redundantly. Even when the second knurling portion is provided at a position different from the first knurling portion, the effect of the present invention can be obtained, but depending on the thickness of the hard coat layer or the hard coat layer and the functional layer, the thickness of the embossed roll unevenness portion. May need to be increased, and the accuracy during embossing tends to decrease. In addition, when the transparent plastic film is wound as a roll-shaped film, the uneven portion thickness tends to vary due to the pressure received inside the winding.

However, when the heated embossing roll is pressed as in the present invention and the knurling portion is processed in an overlapping manner, the unevenness of the formed first knurling portion can be used, so the unevenness thickness of the embossing roll is made so large. It is possible to easily form an uneven part with a desired thickness with high accuracy, and to process the embossing multiple times by processing the knurling part by overlapping the uneven part. Can be formed.

  The 1st knurling part and 2nd knurling part which concern on this invention should just be formed in the at least one surface of the film, and may be formed in both surfaces. The thickness of the knurling portion is necessary to obtain the effect of the present invention to be thicker than the thickness of the optical functional layer including the hard coat layer, and the total thickness of the knurling portions of the first knurling portion and the second knurling portion is determined. It is preferable to make it into the range of 5 micrometers-30 micrometers. Preferably it is the range of 10 micrometers-20 micrometers.

  If the total thickness is less than 5 μm, a minute unevenness of the film surface called yuzu skin tends to occur. On the other hand, if the thickness exceeds 30 μm, the thickness of the winding end portion increases (ear-out failure), and the film is deformed to deteriorate the winding shape.

  When the width of the transparent plastic film substrate is 1.4 m or more, the production efficiency and the utilization efficiency when the antireflection film is applied to a display device are high, preferably 1.4 m to 4 m, and particularly preferably 1 .4m-3m. When such a wide transparent plastic film substrate is used, the first knurling portion and the second knurling portion are preferably provided not only at the end of the substrate film but also inside thereof. That is, it is also preferable to provide a plurality of rows of knurling portions 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.

  In the present invention, the thickness of the knurling part on the winding core side is more than the thickness of the knurling part on the winding side in order to improve the uniformity of the winding core side to the winding center part to the winding outside when the optical film is wound into a roll. The difference in thickness is preferably in the range of 1 μm to 10 μm, more preferably in the range of 3 μm to 8 μm. For example, by changing the embossing roll so that the core side emboss thickness (15 μm) / winding center part emboss thickness (10 μm) / winding side emboss thickness (5 μm) are combined, the core side direction Even if the embossing is pressed by the winding pressure, a desired embossing thickness can be ensured.

(Heat treatment)
A hard coat layer having these knurling portions or an optical film coated with a hard coat layer and a functional layer is wound into a roll shape, and is heated in a roll shape at 42 ° C. or higher for 3 days or longer. When performing, it is preferable to heat at a heating rate of 10 ° C. to 30 ° C./day during the heat treatment. The treatment temperature is preferably in the range of 50 ° C to 120 ° C, and the period is preferably 3 days to 30 days.

  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.

  When winding the hard coat layer having these knurling portions or the optical film coated with the hard coat layer and the functional layer in a roll shape, the wound core may be any material, regardless of the core on the cylinder. However, it is preferably a hollow plastic core, and the plastic material may be any heat-resistant plastic that can withstand the heat treatment temperature. For example, phenol resin, xylene resin, melamine resin , Resins such as 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 film substrate is 80 cm or more. It is preferably 1 m or more.

  When the heat treatment is performed in a state where the roll wound around the plastic core is coated with the hard coat layer or the hard coat layer and the functional layer on the long transparent plastic film substrate in this way. The roll is preferably rotated, and the rotation is preferably performed at a speed of 1 rotation or less per minute, and may be continuous or intermittent. Moreover, it is preferable to perform rewinding of the roll once or more during the heating period.

(Transparent plastic film substrate)
Next, the transparent plastic film substrate that can be used in the present invention will be described.

  The transparent plastic film substrate according to the present invention is easy to manufacture, has good adhesion to the actinic radiation curable resin layer, is optically isotropic, and is optically transparent. There are some preferable requirements.

  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 transparent plastic film substrate according to the present invention is preferably at least one resin selected from cellulose ester resin, polyester resin, polycarbonate resin, polyethersulfone resin, polyacrylate resin, norbornene resin, and acrylic styrene resin. .

  For example, cellulose ester film, polyester film, polycarbonate film, polyarylate film, polysulfone (including polyethersulfone) film, polyester film such as polyethylene terephthalate, polyethylene naphthalate, 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, ZEONEA (above, 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, a cellulose triacetate film, a polycarbonate film, and a polysulfone (including polyethersulfone) film are preferable, and in the present invention, a cellulose ester film (for example, Konicattak product names KC8UX2MW, KC4UX2MW, KC8UY, KC4UY, KC5UN, KC12UR (Konica) Minolta Opto Co., Ltd.)) is preferably used from the viewpoints of production, cost, transparency, isotropy, adhesion and the like. These films may be films produced by melt casting film formation or films produced by solution casting film formation.

The optical properties of the substrate film thickness direction retardation R _t is 0Nm～300nm, retardation R ₀ in the plane direction those 0nm~1000nm is preferably used.

  In the present invention, it is 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 acetyl group is X and the substitution degree of propionyl group or butyryl group is Y, X and Y are active ray curable resin layers on a base film having a mixed fatty acid ester of cellulose in the following range And an antireflection film provided with an antireflection layer is preferably used.

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

  When cellulose ester is used as the substrate film according to the present invention, the cellulose used as the raw material for the cellulose ester is not particularly limited, and examples thereof include cotton linters, wood pulp (derived from conifers and hardwoods), 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).

  As the cellulose ester used in the present invention, a mixed fatty acid ester of cellulose in which a propionate group or a butyrate group is bonded in addition to an acetyl group such as cellulose acetate propionate, cellulose acetate butyrate, or cellulose acetate propionate butyrate Are also preferably used. The butyryl group forming butyrate may be linear or branched.

  Cellulose acetate propionate containing a propionate group as a substituent has excellent water resistance and is useful as a film for a liquid crystal image display device.

  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, and when these ratios are small, it also has a role of promoting the dissolution of the cellulose ester of a 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 cellulose ester film used in the present invention is preferably at least stretched in the width direction, and is 1.01 times to the width direction when the residual solvent amount is 3% by mass to 40% by mass in the solution casting process. The film is preferably stretched 1.5 times. More preferably, biaxial stretching is performed in the width direction and the longitudinal direction, and when the residual solvent is 3% by mass to 40% by mass, the width direction and the longitudinal direction are 1.01 times to 1.5 times, respectively. It is desirable to be stretched. By doing in this way, the light diffusable film excellent in planarity and light diffusibility can be obtained.

  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 carrying out biaxial stretching and performing the knurling described above, it is possible to remarkably improve the deterioration of the winding shape during storage of the long optical film in the form of a roll.

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

The cellulose ester film support according to the present invention preferably has a thickness of 10 μm to 100 μm, more preferably 40 μm to 80 μm, and moisture permeability conforms to JIS Z 0208 (25 ° C., 90% RH). The measured value is preferably 200 g / m ² · 24 hours or less, more preferably 10 to 180 g / m ² · 24 hours or less, and particularly preferably 160 g / m ² · 24 hours or less. . In particular, it is preferable that the film thickness is 10 μm to 80 μm and the moisture permeability is within the above range.

  The transparent plastic film according to the present invention is preferably used as a long film. Specifically, the transparent plastic film has a thickness of about 100 m to 5000 m and is usually provided in a roll shape. Moreover, it is preferable that the width | variety of a base film is 1.3-4 m from a viewpoint of exhibiting the effect of the manufacturing method of the hard coat film for optical thin film layer formation of this invention 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 or 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.

  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 little 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 the ultraviolet absorber preferably used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate 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- 4-Hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate (TINUVIN109, 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 long 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.

  Moreover, in order to give slipperiness to the cellulose-ester film used for this invention, the microparticles | fine-particles similar to what was described with the application layer containing actinic ray curable resin can be used.

  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, the unevenness | corrugation about 0.1-1.0 micrometer high can be formed in the film surface, and, 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 preferable because liquid turbidity with respect to the added amount 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 a 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. Those in which the fibers are mesh cloth are 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.

  The cellulose ester used in the present invention is preferably used as a support with a small amount of bright spot foreign matter when formed into a film. 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 bright spot foreign matter by filtration, it is preferable to filter the composition in which a plasticizer is added and mixed, rather than filtering a 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.

  The functional layer of the present invention is preferably an antireflection layer provided on the hard coat layer.

  Next, the coating layer useful for the antireflection film provided with the antireflection layer according to the present invention will be described.

  The antireflection layer or other thin film of the present invention may be directly formed on the film-like or sheet-like substrate, but may be formed thereon via another layer.

  In the present invention, examples of the coating layer (thin film forming side coating layer) applied to the surface on the thin film forming side of the substrate include a hard coat layer, an antiglare layer, an adhesive layer, and an antistatic layer. In particular, in the case of an antireflection film, it is necessary to provide a hard coat layer as an “other layer” in order to increase the surface hardness of the antireflection film. It is. Further, a back coat layer may be provided on the side where the antireflection layer or other thin film is formed and the side opposite to the substrate.

  Here, a hard coat layer used for an antireflection film will be described as a coating layer as an “other layer” useful in the present invention.

  The hard coat layer is preferably a layer containing an ultraviolet curable compound (resin) that is cured by ultraviolet rays, and an antireflection film excellent in scratch resistance can be obtained.

  The ultraviolet curable resin layer of the hard coat layer is preferably a resin layer formed by polymerizing a component containing an ethylenically unsaturated monomer. Here, the ultraviolet curable resin layer refers to a layer mainly composed of a resin which is cured through a crosslinking reaction or the like by irradiation with an active ray such as an electron beam in addition to ultraviolet rays. Typical examples of the ultraviolet curable resin include an ultraviolet curable resin and an electron beam curable resin. However, a resin that is cured by irradiation with active rays other than ultraviolet rays and electron beams 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 curing 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 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), 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 from the 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, silicon 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 blended so as to be 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 for applying the hard coat layer, the antiglare layer, or the back coat layer to the substrate, 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 is used. I can do it. 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.

(Back coat layer)
The cellulose ester film used in the present invention is preferably provided with a back coat layer containing fine particles on the back side.

  Examples of the fine particles contained in the back coat layer useful in the present invention include fine particles of inorganic compounds or fine particles of organic compounds. Fine particles contained in the cellulose ester film described above, the particle diameter of the fine particles, and the apparent specific gravity of the fine particles. The dispersion method is almost the same.

  The amount of fine particles added to the binder of the backcoat layer is preferably 0.01 parts by mass to 1 part by mass, more preferably 0.05 parts by mass to 0.5 parts by mass with respect to 100 parts by mass of the resin. Most preferred is 08 to 0.2 parts by weight. 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.

  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 for the back coat layer include vinyl chloride / vinyl acetate copolymer, vinyl chloride resin, vinyl acetate resin, copolymer of vinyl acetate and vinyl alcohol, partially hydrolyzed vinyl chloride / vinyl acetate copolymer, and chloride. Vinyl homopolymer or copolymer such as vinyl / 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 acetate Cellulose ester resins such as propionate, cellulose diacetate, cellulose triacetate, cellulose acetate phthalate, cellulose acetate butyrate resin, maleic acid and / or Acrylic acid copolymer, acrylic ester copolymer, acrylonitrile / styrene copolymer, chlorinated polyethylene, acrylonitrile / chlorinated polyethylene / styrene copolymer, methyl methacrylate / butadiene / styrene copolymer, acrylic resin, polyvinyl acetal resin, polyvinyl butyral resin, polyester polyurethane resin , Polyether polyurethane resin, polycarbonate polyurethane resin, polyester resin, polyether resin, polyamide resin, amino resin, styrene / butadiene resin, rubber resin such as butadiene / acrylonitrile resin, silicon resin, fluorine resin, polymethyl methacrylate, Examples include polymethyl methacrylate and polymethyl acrylate copolymers. The present invention is not limited to, et al. Particularly preferred are cellulose resin layers such as cellulose diacetate and cellulose acetate propionate.

  Next, the antireflection layer, which is a functional layer of the present invention, and the antireflection film coated therewith will be described.

  In the antireflection 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 is formed on the above-mentioned transparent plastic film substrate to form an antireflection layer. It is preferable. The antireflection layer may be formed directly on the substrate, but at least one hard coat layer or other coating layer may be provided and formed on a long substrate film having an uneven surface. 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 antireflection film excellent in scratch resistance can be obtained by forming the metal oxide layer according to the present invention on such a resin layer cured by ultraviolet rays.

  A metal oxide layer particularly preferably used as an example of the antireflection layer of the present invention will be described.

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

  Methods for providing the metal oxide layer include coating, atmospheric pressure plasma CVD, sputtering, vapor deposition, and the like. In the present invention, the antireflection layer is formed by coating.

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

  The basic structure of the antireflection film of the present invention will be described. For example, a preferred antireflection film has a layer structure in the order of a transparent support, a hard coat layer, a medium refractive index layer, a high refractive index layer, and a low refractive index layer. The transparent support, the middle refractive index layer, 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 transparent support <refractive index of hard coat layer <refractive index of medium refractive index layer <refractive index of high refractive index layer.

  In an antireflection film having a medium refractive index layer, a high refractive index layer, and a low refractive index layer, as described in JP-A No. 59-50401, the medium refractive index layer represents the following formula (1), When the refractive index layer satisfies the following mathematical formula (2) and the low refractive index layer satisfies the following mathematical formula (3), it is possible to further reduce the average reflectance as an antireflection film.

(Hλ / 4) × 0.7 <n ₃ d ₃ <(hλ / 4) × 1.3 (1)
In formula (1), h is a positive integer (generally 1, 2 or 3), n ₃ is the refractive index of the medium refractive index layer, and d ₃ is the film thickness (nm) of the medium refractive index layer. It is. Further, λ is a wavelength, which is a value in the range of 350 to 800 (nm).

(Jλ / 4) × 0.7 <n ₄ d ₄ <(jλ / 4) × 1.3 (2)
In formula (2), j is a positive integer (generally 1, 2 or 3), n ₄ is the refractive index of the high refractive index layer, and d ₄ is the film thickness (nm) of the high refractive index layer. It is. Further, λ is a wavelength, which is a value in the range of 350 to 800 (nm).

(Kλ / 4) × 0.7 <n ₅ d ₅ <(kλ / 4) × 1.3 (3)
In Equation (3), k is a positive odd number (generally 1), n ₅ is the refractive index of the low refractive index layer, and d ₅ is the film thickness (nm) of the low refractive index layer. Further, λ is a wavelength, which is a value in the range of 350 to 800 (nm).

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

  In addition, a layer structure in the order of a transparent support, a hard coat layer (antiglare layer), a high refractive index layer, a low 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 and medium refractive index>
In the present invention, in order to reduce the reflectance, it is preferable to provide a high refractive index layer between the transparent support or the transparent support provided with the hard coat layer and the low refractive index layer. In addition, it is preferable to provide an intermediate refractive index layer between the transparent support 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 refractive index of the medium refractive index layer is adjusted to be an intermediate value between the refractive index of the transparent support and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.55-1.80. The thickness of the high refractive index layer and the medium refractive index layer is preferably 5 nm to 1 μm, more preferably 10 nm to 0.2 μm, and most preferably 30 nm to 0.1 μm. The haze of the high refractive index layer and the medium 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 and the medium refractive index layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher, with a pencil hardness of 1 kg. The high refractive index layer and the medium refractive index layer preferably contain inorganic fine particles and a binder polymer.

The inorganic fine particles used for the high refractive index layer and the medium refractive index layer preferably have a refractive index of 1.80 to 2.80, more preferably 1.90 to 2.80. The primary particles of the inorganic fine particles preferably have a weight average diameter of 1 to 150 nm, more preferably 1 to 100 nm, and most preferably 1 to 80 nm. The weight average diameter of the inorganic fine particles in the layer is preferably 1 to 200 nm, more preferably 5 to 150 nm, still more preferably 10 to 100 nm, and most preferably 10 to 80 nm. . The average particle diameter of the inorganic fine particles is measured by a light scattering method if it is 20-30 nm or more and by an electron micrograph if it is 20-30 nm or less. The specific surface area of the inorganic fine particles, a measured value by the BET method, is preferably from 10 to 400 m ² / g, more preferably from 20 to 200 m ² / g, a 30 to 150 m ² / g Is most preferred.

  The inorganic fine particles are preferably particles formed from a metal oxide or sulfide. Examples of metal oxides or sulfides include titanium dioxide (eg, rutile, rutile / anatase mixed crystal, anatase, amorphous structure), tin oxide, indium oxide, zinc oxide, zirconium oxide and zinc sulfide. Of these, titanium oxide, tin oxide, and indium oxide are particularly preferable. The inorganic fine particles are mainly composed of oxides or sulfides of these metals and can further contain other elements. The main component means a component having the largest content (mass%) among the components constituting the particles. Examples of other elements include Ti, Zr, Sn, Sb, Cu, Fe, Mn, Pb, Cd, As, Cr, Hg, Zn, Al, Mg, Si, P, and S.

  The inorganic fine particles may be surface-treated. The surface treatment can be performed using an inorganic compound or an organic compound. Examples of inorganic compounds used for the surface treatment include alumina, silica, zirconium oxide and iron oxide. Of these, alumina and silica are preferable. Examples of the organic compound used for the surface treatment include polyols, alkanolamines, stearic acid, silane coupling agents, and titanate coupling agents. Of these, a silane coupling agent is most preferable. It may be processed by combining two or more types of surface treatments. The shape of the inorganic fine particles is preferably a rice grain shape, a spherical shape, a cubic shape, a spindle shape, or an indefinite shape. Two or more kinds of inorganic fine particles may be used in combination in the high refractive index layer and the medium refractive index layer.

  The ratio of the inorganic fine particles in the high refractive index layer and the medium refractive index layer is preferably 5 to 65% by volume, more preferably 10 to 60% by volume, and still more preferably 20 to 55% by volume.

  The inorganic fine particles are supplied to a coating liquid for forming a high refractive index layer and a medium 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), ester (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 inorganic 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.

  The high refractive index layer and the medium refractive index layer preferably use 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 ratio 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 prepared by blending a monomer for generating a cross-linked polymer to prepare a coating solution for forming a high refractive index layer and a medium refractive index layer, and is generated by a polymerization reaction simultaneously with or after coating of the coating solution. Is preferred. 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 Co., Ltd.) 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.

  For the medium refractive index layer and the high refractive index layer, it is preferable to use a polymer having a relatively high refractive index. 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.

  A high refractive index layer or a medium 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>
Examples of the low refractive index layer include a low refractive index layer formed by crosslinking a fluorine-containing resin that is crosslinked by heat or ionizing radiation (hereinafter also referred to as “fluorinated resin before crosslinking”), a low refractive index layer by a sol-gel method, and particles. And a binder polymer, and 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 1.30 to 1.50, more preferably 1.35 to 1.49.

  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 cross-linked structure by adding a compound having a group that reacts with a functional group in the polymer and one or more reactive groups after copolymerization. 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 monomer used to form the fluorinated copolymer before cross-linking is preferably 20 to 70 mol%, more preferably 40 to 70 mol%, and 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 (R) AF (DuPont), polyvinylidene fluoride, Lumiflon (Asahi Glass), Opstar (JSR) and the like. It is done.

  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 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 the fine particles and the microvoids in the particles 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 air 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 50% 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. 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), Mention may be made of 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-dichlorohexanediacrylate, 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.

  In addition to the above-described components (inorganic fine particles, polymer, dispersion medium, polymerization initiator, polymerization accelerator), each layer of the antireflection film or coating solution thereof includes a polymerization inhibitor, a leveling agent, a thickener, a coloration inhibitor, You may add a ultraviolet absorber, a silane coupling agent, an antistatic agent, and an adhesion imparting agent. Each layer of the antireflection film is 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).

(Polarizer)
The polarizing plate can be produced by a general method. The back surface side of the antireflection film of the present invention is subjected to alkali saponification treatment, and a completely saponified polyvinyl alcohol aqueous solution is used on at least one surface of a polarizing film prepared by immersing and stretching the treated antireflection film in an iodine solution. It is preferable to bond them together. The antireflection film may be used on the other surface, or another polarizing plate protective film may be used. With respect to the antireflection film of the present invention, the polarizing plate protective film used on the other surface has an in-plane retardation Ro of 590 nm, a phase difference of 20 to 70 nm, and Rt of 100 to 400 nm. preferable. 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 it in combination with the antireflection 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 (manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used as a commercially available transparent support.

  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 antireflection 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.

  A conventional polarizing plate using an antireflection film is inferior in flatness, and when a reflected image is seen, fine wavy unevenness is recognized, and the unevenness of wavy increases by a durability test under conditions of 60 ° C. and 90% RH. On the other hand, the polarizing plate using the antireflection 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 antireflection film of the present invention is a reflective type, transmissive type, transflective type LCD or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type, etc. Preferably used. In addition, the antireflection film of the present invention has very little uneven color of reflected light of the antireflection layer, and has excellent flatness, and various displays such as a plasma display, a field emission display, an organic EL display, an inorganic EL display, and electronic paper. It is also preferably used for an apparatus. 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.

Example 1
A cellulose ester film having a length of 2600 m, a width of 1.4 m, and a film thickness of 80 μm was produced as follows. The transparent long base film was provided with a first knurling portion as shown below. Next, a back coat layer is provided on one side of the substrate film, and further provided on the opposite side of the back coat layer without winding up the hard coat layer, and then the following antireflection layer is applied to form an optical film. No. 1-9 were produced.

(Production of cellulose ester film)
<Preparation of dope A>
Cellulose triacetate (acetyl group substitution degree 2.9) 100 parts by weight Triphenyl phosphate 10 parts by weight Biphenyl diphenyl phosphate 2 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0.5 part by weight Aerosil R972V (Nippon Aerosil ( 0.2 mass part Methylene chloride 405 mass parts Ethanol 45 mass parts The above is put into a closed-type dissolution kettle, completely dissolved at 70 ° C. with stirring, and after cooling, manufactured by Azumi Filter Paper Co., Ltd. Azumi Filter Paper No. Filtration using 244 gave Dope A. The prepared dope A was cast on a stainless steel belt. The solvent was evaporated on the stainless steel belt, and the web was peeled off from the stainless steel belt. The peeled web was introduced into a tenter dryer, and both ends were gripped with clips and dried at 80 ° C. while being stretched 1.1 times in the width direction, and placed in a roll dryer having respective drying zones of 110 ° C. and then 125 ° C. Drying was terminated while being conveyed through a number of arranged rolls to produce a cellulose ester film.

(Coating back coat layer)
The following backcoat layer coating composition was die-coated so as to have a wet film thickness of 13 μm, and dried at a drying temperature of 90 ° C. to coat a backcoat layer.

<Backcoat layer coating composition>
Acetone 30 parts by weight Ethyl acetate 45 parts by weight Isopropyl alcohol 10 parts by weight Diacetyl cellulose 0.5 parts by weight Ultrafine silica 2% acetone dispersion (Aerosil 200V) 0.2 parts by weight (manufactured by Nippon Aerosil Co., Ltd.)
(Coating of hard coat layer)
The following hard coat layer coating composition is die-coated on the surface opposite to the back coat layer, dried at 80 ° C. for 5 minutes, then irradiated with 160 mJ / cm ² of ultraviolet rays, and the total dry film thickness with the following antireflection layer. Was provided with a hard coat layer so as to be 5 μm, and a hard coat film was produced.

<Hard coat layer coating composition>
Dipentaerythritol hexaacrylate 70 parts by weight Trimethylolpropane triacrylate 30 parts by weight Photoinitiator 4 parts by weight (Irgacure 184 (manufactured by Ciba Specialty Chemicals))
Ethyl acetate 150 parts by mass Propylene glycol monomethyl ether 150 parts by mass Silicon compound 0.4 parts by mass (BYK-307 (by Big Chemie Japan))
When the pencil hardness of the hard coat layer was measured, it showed a hardness of 3H and an abrasion resistance effect.

(Preparation of antireflection film)
An antireflection layer was formed on the hard coat film prepared above.

  On the hard coat film, the following refractive index layer coating solution is coated using a bar coater, dried at 60 ° C., and then irradiated with ultraviolet rays to cure the coated layer. 1.72) was formed. On top of that, the following coating solution for a high refractive index layer was applied using a bar coater, dried at 60 ° C., and then irradiated with ultraviolet rays to cure the coating layer, and a high refractive index layer (refractive index 1.9). Formed. Furthermore, the following coating solution for a low refractive index layer was applied using a bar coater, dried at 60 ° C., then irradiated with ultraviolet rays to cure the coating layer, and the low refractive index layer (refractive index 1.45). ) To form an antireflection film.

<Preparation of medium refractive index layer / high refractive index layer / low refractive index layer>
(Preparation of titanium dioxide dispersion)
Titanium dioxide (primary particle mass average particle diameter: 50 nm, refractive index: 2.70) 30 parts by mass, anionic diacrylate monomer (PM21, Nippon Kayaku Co., Ltd.) 4.5 parts by mass, cationic methacrylate monomer (DMAEA, manufactured by Kojin Co., Ltd.) 0.3 parts by mass and 65.2 parts by mass of methyl ethyl ketone were dispersed by a sand grinder to prepare a titanium dioxide dispersion.

(Preparation of coating solution for medium refractive index layer)
In 151.9 g of cyclohexanone and 37.0 g of methyl ethyl ketone, 0.14 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and 0.04 g of a photosensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) were dissolved. Further, 6.1 g of the above titanium dioxide dispersion and 2.4 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.) were added and stirred at room temperature for 30 minutes. The solution was filtered through a polypropylene filter having a pore diameter of 0.4 μm to prepare a coating solution for a medium refractive index layer. When this coating solution was applied to a cellulose ester film and dried and the refractive index after UV curing was measured, a medium refractive index layer having a refractive index of 1.72 and a dry film thickness of 85 nm was obtained.

(Preparation of coating solution for high refractive index layer)
In 1152.8 g of cyclohexanone and 37.2 g of methyl ethyl ketone, 0.06 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and 0.02 g of a photosensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) were dissolved. Furthermore, the ratio of the above titanium dioxide dispersion and the titanium dioxide dispersion of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, Nippon Kayaku Co., Ltd.) is increased, and the refractive index of the high refractive index layer is increased. The amount was adjusted so as to be a ratio, and the mixture was stirred at room temperature for 30 minutes, and then filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a high refractive index layer. When this coating liquid was applied to a cellulose ester film and dried, and the refractive index after UV curing was measured, a high refractive index layer having a refractive index of 1.9 and a dry film thickness of 68 nm was obtained.

(Preparation of coating solution for low refractive index layer)
Silane coupling agent (KBM-503, Shin-Etsu Silicone Co., Ltd.) 3 g and 0.1 mol / L hydrochloric acid 2 g are added to 200 g of methanol dispersion of silica fine particles having an average particle size of 15 nm (methanol silica sol, manufactured by Nissan Chemical Co., Ltd.). In addition, the mixture was stirred at room temperature for 5 hours and then allowed to stand at room temperature for 3 days to prepare a dispersion of silica fine particles treated with silane coupling. To 35.04 g of the dispersion, 58.35 g of isopropyl alcohol and 39.34 g of diacetone alcohol were added. Further, 1.02 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and a solution obtained by dissolving 0.51 g of a photosensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) in 772.85 g of isopropyl alcohol were added. Furthermore, 25.6 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.) was added and dissolved. 67.23 g of the resulting solution was added to the above dispersion, a mixture of isopropyl alcohol and diacetone alcohol. The mixture was stirred for 20 minutes at room temperature and filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a low refractive index layer. When this coating liquid was applied to a cellulose ester film and dried, and the refractive index after UV curing was measured, the refractive index was 1.45 and the dry film thickness was 100 nm.

<< Production of knurling part >>
A heated embossing roll was pressed against the cellulose ester film and the film coated with the hard coat layer / antireflection layer to prepare a knurling portion as follows.

(Optical film No. 1: Comparative example)
A first knurling portion having a thickness of 7 μm and a width of 10 mm was provided at both ends of a cellulose ester film having a width of 1.4 m. When the thickness of the 1st knurling part was measured when winding up a cellulose-ester film and coating a backcoat layer, it varied in the range of 3-6 micrometers. Furthermore, the second knurling part was not provided in the optical film coated with an antireflection layer by a coating type.

(Optical film No. 2: Comparative example)
An optical film having a thickness of 7 μm and a width of 10 mm provided at both ends of a cellulose ester film having a width of 1.4 m, and further coated with an antireflection layer, has a thickness of 5 μm and a width of 10 mm on the inner side from the first knurling portion. A second knurling part was provided.

(Optical film No. 3: present invention)
A first knurling portion having a thickness of 7 μm and a width of 10 mm is provided at both ends of a 1.4 m wide cellulose ester film, and a second knurling having a thickness of 3 μm and a width of 10 mm is provided on the first knurling portion on an optical film coated with an antireflection layer. Set up a section.

(Optical film No. 4: present invention)
A first knurling portion having a thickness of 7 μm and a width of 10 mm was provided at both ends of a cellulose ester film having a width of 1.4 m. Further, a second knurling portion having a thickness of 5 μm and a width of 10 mm was provided on the first knurling portion on the optical film coated with the antireflection layer.

(Optical film No. 5: Comparative example)
An optical film having a thickness of 7 μm and a width of 10 mm provided at both ends of a cellulose ester film having a width of 1.4 m, and further coated with an antireflective layer, has a thickness of 10 μm and a width of 10 mm inside the first knurling portion. A second knurling part was provided.

(Optical film No. 6: present invention)
A first knurling portion having a thickness of 7 μm and a width of 10 mm is provided at both ends of a cellulose ester film having a width of 1.4 m, and an antireflection layer is further applied, and then a second knurling having a thickness of 10 μm and a width of 10 mm is provided on the first knurling portion. Set up a section.

(Optical film No. 7: present invention)
A first knurling portion having a thickness of 7 μm and a width of 10 mm is provided at both ends and a central portion of a cellulose ester film having a width of 1.8 m, and an antireflection layer is further applied, and then a thickness of 10 μm and a width of 10 mm is formed on the first knurling portion. The 2nd knurling part was provided in the film edge part and the center part.

(Optical film No. 8: present invention)
A first knurling portion having a thickness of 7 μm and a width of 10 mm was provided at both ends of the cellulose ester film having a width of 1.4 m. After the hard coat layer was applied, a second knurling portion having a thickness of 10 μm and a width of 10 mm was provided on the first knurling portion and wound, and then an antireflection layer was applied.

(Optical film No. 9: present invention)
After providing a first knurling part with a thickness of 7 μm and a width of 10 mm at both ends of a cellulose ester film having a width of 1.4 m, and further applying an antireflection layer, the thickness is on the first knurling part from the beginning to 1300 m of the roll film. A second knurling part having a width of 15 μm and a width of 10 mm is formed on a first knurling part having a thickness of 10 μm and a second knurling part having a width of 10 mm on a first knurling part having a thickness of 2000 to 2600 m and a width of 10 mm. The second knurling portion was provided by continuously changing the embossing roll, and then wound up. As a result, a roll-shaped antireflection film having the thickest emboss thickness on the winding core side was obtained.

  The prepared antireflection film was heat-treated under the following conditions.

  A: The roll film was heated from room temperature (23 ° C.) to 65 ° C. at a rate of temperature increase of 21 ° C./day for 2 days, then kept at 65 ° C. and allowed to stand for 7 days, and further 21 ° C./day. The temperature was returned to room temperature over 2 days at a temperature lowering rate.

  B: The roll film was heated from room temperature (23 ° C.) to 65 ° C. at a rate of 42 ° C./day for 1 day, then kept at 65 ° C. and allowed to stand for 7 days, and further 42 ° C./day The temperature was returned to room temperature over 1 day at a temperature lowering rate.

  The details are summarized in Table 1.

  The following evaluation was performed about the obtained sample.

<Evaluation>
<Deformation of winding>
5: No winding deformation 4: Little winding deformation 3: Winding is slightly deformed 2: Winding deformation is clearly seen 1: Large deformation is seen in winding Practical evaluation criteria 4 or higher It is a level that can be used.

<Yuzu skin failure>
The surface of each sample was visually observed to evaluate the presence or absence of fine irregularities on the skin.

○: No yuzu skin failure occurred. Δ: Some yuzu skin failure occurred. X: Many yuzu skin failures occurred. <Color unevenness: L ^* a ^* b ^* value measurement>
Each sample is prepared with a combination of conditions as shown in Table 1, and the evaluation sample takes a length of 200 mm for each part of the 10th volume from the winding core, the central part of the winding, and the 10th volume from the outside of the winding. Take a total of nine 100mm squares with three pieces of the inner part and the central part 50mm from the end of the sample, measure L ^* a ^* b ^* by the following method for the central part of each sample, and set the maximum value as b ^* value width Table 1 shows the minimum values. The smaller the difference between the maximum and minimum values, the better the color unevenness.

The L ^* a ^* b ^* value of the antireflection layer was obtained from the spectral reflectance measured by the SCI (including regular reflection light) method using a chromaticity meter CM-2022 (manufactured by Konica Minolta Sensing Co., Ltd.). The sample was subjected to a roughening treatment on the back surface on the measurement side, then subjected to light absorption treatment with black spray (transmittance at 370 nm to 730 nm of less than 10%), and measured on a black table.

  The results are shown in Table 1 below.

  From the above table, sample No. 4, 5, 8, 9, 10, and 11 show that there is no deformation of the windings, no damage to the skin, and no color unevenness. In particular, sample no. It turned out that the said characteristic becomes especially favorable for the sample which thickened the thickness of the knurling part like 11 to the winding core side.

  Moreover, it turned out that the sample which performed the temperature rising and temperature-fall rate of the heat processing in the range of 10 degreeC-30 degreeC / day improves a yuzu skin failure and color nonuniformity.

Example 2
When the same heat treatment as in Example 1 was performed on a lot whose production date was changed with the same roll as the sample produced in Example 1, and the same evaluation was performed, the sample of the present invention had almost no difference between lots. Was confirmed.

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

Explanation of symbols

F transparent plastic film base material 1 1st knurling part 2 2nd knurling part 3 hard coat layer 4 antireflection layer

Claims (8)

In the method for producing an optical film having a hard coat layer or a hard coat layer and a functional layer on a transparent plastic film substrate having at least one knurling portion in the film winding direction, the hard coat layer or the hard coat layer and the function A method for producing an optical film, wherein a heated embossing roll is pressed onto the knurling portion and the knurling portion is processed in an overlapping manner after the step of applying the adhesive layer. The method for producing an optical film according to claim 1, wherein the total thickness of the knurling portion that has been processed by overlapping the knurling portion is set to a range of 5 μm to 30 μm. After applying a hard coat layer or a hard coat layer and a functional layer on a transparent plastic film substrate having at least one knurling part in the film winding direction, the heated embossing roll is pressed onto the knurling part to overlap. The optical film processed in the knurling part is wound into a roll shape, and is heated to 42 ° C. for 3 days or more in the state of being wound in a roll shape. A method for producing an optical film, comprising heating at a rate of temperature increase of -30 ° C / day. The method for producing an optical film according to claim 3, wherein the total thickness of the knurling portions that are processed by overlapping knurling is set to a range of 5 μm to 30 μm. 5. The method for producing an optical film according to claim 3, wherein the heat treatment is performed at a treatment temperature of 50 to 120 ° C. for a period of 3 to 30 days. When the optical film is wound into a roll, the total thickness of the knurling part on the winding core side is thicker than the total thickness of the knurling part on the outside of the winding, and the difference in thickness is in the range of 1 μm to 10 μm. The manufacturing method of the optical film of any one of Claims 1-5. 2. The transparent plastic film substrate is at least one selected from cellulose ester resin, polyester resin, polycarbonate resin, polyethersulfone resin, polyacrylate resin, norbornene resin, and acrylic styrene resin. The manufacturing method of the optical film of any one of -6. The functional layer is a layer that contains at least one of a metal oxide, a metal oxynitride, a metal nitride, an organic polymer, and a liquid crystal compound and imparts an antireflection function. The manufacturing method of the optical film of any one of these.

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