JP2007293302A - Manufacturing method of optical film, the optical film and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of optical film, capable of simultaneously forming at least two coating layers on a transparent support and that is low cost and has high productivity. <P>SOLUTION: The manufacturing method of optical film comprises a step of simultaneously coating and forming at least two coating layers, by using at least two kinds of coating solutions containing solvent and solute on the transparent support; and a step of drying the solvent in at least two coating layers. When at least two coating layers are set to be 1, 2 to n-1, and n layers, in this order starting from the uppermost surface toward the transparent support, the main component of the solute in the n-th layer is insoluble or is hardly soluble with respect to the main component of the solvent in the (n-1)-th layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical film manufacturing method, an optical film, and an image display device.

  Anti-reflection films such as liquid crystal display (LCD), plasma display panel (PDP), electroluminescence display (ELD), cathode tube display (CRT), field emission display (FED), surface electric field display (SED) In various image display devices, it is disposed on the surface of a display in order to prevent a decrease in contrast due to reflection of external light or reflection of an image. Therefore, in addition to high antireflection performance, the antireflection film is required to have high transmittance, high physical strength (such as scratch resistance), chemical resistance, and weather resistance (such as moisture and heat resistance).

  A method of applying a coating composition (wet coating) has been proposed for forming an antireflection layer (high refractive index layer, medium refractive index layer, low refractive index layer, etc.) used for an antireflection film.

  When producing an antireflection film by a coating method, a coating composition prepared by dissolving or dispersing a film-forming composition having a specific refractive index in a solvent is coated on a transparent support substrate, dried, and if necessary It is necessary to form a single-layer or multi-layer thin film by curing. In the case of a single layer, a layer having a lower refractive index than that of the substrate (low refractive index layer) may be formed with an optical thickness of 1/4 of the design wavelength. If lower reflection is required, a layer having a higher refractive index (high refractive index layer) than that of the transparent support may be formed between the substrate and the layer having a low refractive index. In order to reduce the refractive index, an aspect in which an intermediate refractive index layer having a refractive index intermediate between the transparent support and the high refractive index layer is provided on the transparent substrate side of the high refractive index layer is also proposed (Patent Document 1). ).

When forming a plurality of layers having different refractive indexes, problems such as poor productivity and cost increase occur due to an increase in the number of coating processes, and scratch resistance deteriorates when the adhesion between the two layers is low. Since a problem occurs, a technique for simultaneously forming two different layers has been proposed as means for solving the problem (Patent Documents 2 and 3). For example, the coating liquid containing both the fluorine-containing polymer and the inorganic fine particles is applied and cured once, thereby simultaneously forming the high refractive index layer containing the inorganic fine particles and the low refractive index layer containing the fluorine-containing polymer. A method of manufacturing an antireflection film is disclosed (Patent Document 2). That is, two coating layers are formed by single coating once. However, no specific proposal has yet been made to achieve low reflectance, neutral color, high scratch resistance, high productivity, good surface condition, etc. in the optical film manufacturing method. It is desired.
JP 2003-121606 A JP 2004-317734 A JP 2004-359930 A

An object of the present invention is to provide a low-cost and high-productivity optical film manufacturing method in which at least two coating layers are simultaneously formed on a transparent support.
Another object of the present invention is to provide a method for producing an optical film that is excellent in at least one of low reflectance, uniform surface without unevenness, neutral color, and scratch resistance.
Furthermore, the present invention provides an image display device having an optical film manufactured by the manufacturing method of the present invention and having at least one of low reflectance, uniform surface shape without unevenness, neutral color tone, and scratch resistance.

As described above, when two or more kinds of coating liquids are applied at the same time, generally, inter-layer mixing occurs, and it is very difficult to control the thickness of the order of 100 nm, such as an optical interference layer, and to form a thin interface capable of optical interference. It is difficult to. As simultaneous multilayer coating, there is a means to gel each layer immediately after coating, as in photographic photosensitive materials, but even in this case it is doubtful whether an interface capable of optical interference can be formed, and an organic solvent was used. In some cases, there are very restrictions only on the conditions of the liquid composition to be gelled, and it is practically impossible to incorporate a function as an optical film. As a result of intensive studies to solve the above-described problems, the present inventors have found that the above-described problems can be solved and the object can be achieved, and the present invention has been completed.
That is, the present invention is as follows.
(1) A step of simultaneously coating and forming at least two coating layers using at least two coating solutions containing a solvent and a solute on a transparent support, and a solvent in the at least two coating layers And drying the
When the at least two coating layers are 1, 2,..., N−1, n layers in order from the outermost surface toward the transparent support, the main component of the solute in the nth layer is n−1. A method for producing an optical film which is insoluble or hardly soluble in a main component of a solvent in a layer.
(2) A step of simultaneously coating and forming at least two coating layers using at least two coating solutions containing a solvent and a solute on a transparent support, and a solvent in the at least two coating layers And drying the
When the at least two coating layers are 1, 2, ..., n-1, n layers in order from the outermost surface toward the transparent support, the main component of the solute in the n-1 layer is the first. The manufacturing method of the optical film as described in (1) which is easily soluble in the main component of the solvent in n layer.
(3) A step of simultaneously coating and forming at least two coating layers on at least two coating solutions containing a solvent and a solute on a transparent support, and a solvent in the at least two coating layers And drying the
The method for producing an optical film, which is a coating liquid that causes liquid-liquid phase separation and separates into two layers when the coating liquid of at least two layers is mixed at the same volume ratio as the coating amount.
(4) A step of simultaneously coating and forming at least two coating layers using at least two coating solutions containing a solvent and a solute on a transparent support, and a solvent in the at least two coating layers And drying the
The coating solution of at least two layers is mixed as a one-phase solution when mixed at the same volume ratio as the coating amount, and the solvent amount is reduced by 10% by weight by drying the solvent in the mixed solution. -The manufacturing method of the optical film which is a coating liquid which raise | generates liquid phase separation and isolate | separates into two layers.

(5) The optical film according to any one of (1) to (4), wherein the coating liquid applied to the outermost layer of the optical film contains a thermosetting or ionizing radiation curable fluorine-containing compound. Production method.
(6) The manufacturing method of the optical film as described in said (5) in which the coating liquid applied to the said outermost layer contains a silicone compound further.
(7) The manufacturing method of the optical film as described in said (5) or (6) in which the said fluorine-containing compound has a silicone structural unit in a molecule | numerator.
(8) The above (1) to (7), wherein the coating liquid of at least one layer applied to any layer other than the outermost layer of the optical film contains a bifunctional or higher polymerizable monomer and / or oligomer. ) Any one of the methods for producing an optical film.
(9) The above (1) to (8), wherein at least one coating liquid applied to any layer other than the outermost layer of the optical film contains translucent particles having an average particle diameter of 1.0 μm or more. ) Any one of the methods for producing an optical film.
(10) The coating liquid of at least one layer applied to any layer other than the outermost layer of the optical film contains inorganic oxide fine particles having an average particle diameter of 100 nm or less and a refractive index of 1.9 or more. The manufacturing method of the optical film in any one of said (1)-(9).

(11) The step of simultaneously coating and forming the at least two coating layers is a step of simultaneously coating and forming at least two coating layers with a composite coater having a slot die and a slide type coating head.
While supporting a web including a transparent support with a backup roller and continuously running, a lower layer is applied on the web using a slot die, and a slide type coating head disposed near the tip of the slot die is provided. The method for producing an optical film according to any one of (1) to (10), wherein at least one upper layer is applied on the lower layer.
(12) The optical film as described in any one of (1) to (11) above, which has a step of curing the coating film by heat treatment and / or ionizing ray irradiation after the step of drying the solvent of the at least two coating layers. Manufacturing method.
(13) An optical film manufactured by the method for manufacturing an optical film according to any one of (1) to (12).
(14) An image display device having the optical film according to (13).

  According to the production method of the present invention, at least two optical layers (for example, a low-refractive index layer and a high-refractive index layer) can be simultaneously formed by using a coating liquid having physical properties and characteristics peculiar to the present invention. That is, it is possible to produce an optical film having at least two optical layers by simultaneously coating and forming at least two coating layers in a single coating step. Therefore, a low-cost and highly productive manufacturing method can be achieved.

  Further, in the production method of the present invention, when a low refractive index coating liquid is used for the outermost coating layer of at least two coating layers, a low reflectance, a uniform surface with no unevenness, and a neutral An optical film (antireflection film, low reflection film, etc.) excellent in at least one of color and scratch resistance can be obtained in a single step. Under specific conditions, an optical film having the same reflectance as that in which the optical layers are sequentially formed and having no unevenness can be obtained in one step.

  Furthermore, the image display device having the optical film manufactured by the manufacturing method of the present invention has a low reflectance and / or a uniform surface without unevenness.

Details of the present invention will be described below.
The first aspect of the present invention includes a step of simultaneously forming and forming at least two coating layers on a transparent support using at least two types of coating solutions containing a solvent and a solute; A step of drying the solvent in the coating layer,
When the at least two coating layers are 1, 2,..., N−1, n layers in order from the outermost surface toward the transparent support, the main component of the solute in the nth layer is n−1. This is a method for producing an optical film that is insoluble or hardly soluble in the main component of the solvent in the layer.

  Further preferred in the first aspect of the present invention is a method for producing an optical film in which the main component of the solute in the n-1th layer is readily soluble in the main component of the solvent in the nth layer.

The second aspect of the present invention comprises a step of simultaneously coating and forming at least two coating layers on at least two kinds of coating solutions containing a solvent and a solute on a transparent support; and A step of drying the solvent in the coating layer,
The at least two-layer coating liquid is a method for producing an optical film which is a coating liquid that undergoes liquid-liquid phase separation and separates into two layers when mixed at the same volume ratio as the coating amount.

The third aspect of the present invention is the step of simultaneously coating and forming at least two coating layers on at least two kinds of coating solutions containing a solvent and a solute on a transparent support; A step of drying the solvent in the coating layer,
The coating solution of at least two layers is mixed as a one-phase solution when mixed at the same volume ratio as the coating amount, and the solvent amount is reduced by 10% by weight by drying the solvent in the mixed solution. -It is a manufacturing method of the optical film which is a coating liquid which raise | generates liquid phase separation and isolate | separates into two layers.

  In the production method of the present invention, an optical film having at least two optical layers can be produced by simultaneously coating, drying and curing at least two coating layers on a transparent support. The optical layer formed of at least two coating layers is not particularly limited, and examples thereof include optical layers such as an antireflection layer, a diffusion layer, and an antiglare layer. Specifically, a hard coat layer, a low refractive index layer, a medium refractive index layer, a high refractive index layer, and the like can be given.

  For example, of at least two coating layers, one layer is a hard coat layer coating solution, and the other at least one layer is a low refractive index coating solution, a medium refractive index layer coating solution, and a high refractive index layer coating solution. An optical film (antireflection film, low reflection film, etc.) that is excellent in at least one of low reflectance, uniform and uniform surface, neutral color, and scratch resistance is used once. It is obtained by the process. In the present invention, it is possible to produce an optical film having at least two optical layers by simultaneously coating and forming at least two coating layers in a single coating step. Therefore, a low-cost and high-productivity manufacturing method can be achieved. Moreover, the manufacturing method of this invention has the advantage that a multilayer optical layer can be formed simultaneously, without forming an optical layer sequentially.

  Furthermore, the image display device having the optical film manufactured by the manufacturing method of the present invention has a low reflectance and / or a uniform surface without unevenness.

[Relationship between solvent and solute in each layer]
The method for producing an optical film of the present invention is sufficient so that when a plurality of coating liquids are applied and dried simultaneously, the solute components of each layer are formed independently without being mixed with each other, and the interface between the layers can optically interfere. It is possible to form a thin film. Most simply, the coating solution and solute components of each layer do not mix, that is, it can be achieved if they are in a relationship that does not dissolve, but for example, a coating solution that simply does not mix, such as an organic solvent solution and an aqueous solution. Even if they are applied to each other, the desired layer structure cannot always be obtained. Specifically, it is necessary that the relationship between adjacent layers satisfies any of the following relationships when simultaneously applied.
Unless otherwise specified, the “solvent” described in the following text refers to the (main component) compound occupying the maximum amount (weight unit) of the volatile components in each layer coating solution, and the “solute” refers to each layer. It means a (main component) compound that occupies the maximum amount (weight unit) among the non-volatile components (solid content) dissolved in the coating solution, and at least these compounds must satisfy the following relationship.
In the present specification, components such as particles that are not dissolved in the coating solution and are in a dispersed state are not treated as solutes.

First, as the first aspect, the solute of the layer (lower layer) arranged on the support side among the adjacent layers is insoluble or hardly soluble in the solvent of the layer (upper layer) arranged on the surface side. Is preferred.
“Insoluble” as used herein refers to a state in which an insoluble component remains when a solute of about 1% by mass is added to the solvent, and “slightly soluble” means that about 10% by mass of a solute is added to the solvent. This means that insoluble components remain or the solution becomes clearly turbid even without precipitation. The liquid was observed under a white fluorescent lamp of 500 lux with black paper as a background in a state where about 10 cc of the solution was filled in a 15 cc transparent glass bottle.
After simultaneous application, each component of both coating solutions diffuses and moves, but the lower layer solute is not compatible with the upper layer solvent, so the lower layer component is prevented from moving to the upper layer, resulting in mixing the upper and lower layers. Can be suppressed.

At this time, the relationship between the upper layer solute and the lower layer solvent is preferable to make the compatibility worse in terms of separating the layers. However, if such a relationship is established, the upper layer is not formed as a uniform layer but is formed in a sea island shape. End up. This is considered to be because when the solvent of the lower layer passes through the upper layer during drying, it cannot be mixed with the solute of the upper layer, so that the solute of the upper layer aggregates and changes the shape of the interface from the layer structure to the spherical structure.
Furthermore, if the solutes of each layer are insoluble in the solvent of the counterpart layer, the solutes of each other are precipitated as a solid phase at the liquid interface, and a uniform interface is no longer formed.
Therefore, as a more preferred embodiment, it is preferable that the upper layer solute is easily soluble in the lower layer solvent.
“Easily soluble” means that even if a solute of about 20% by mass is added to the solvent, it is in a transparent solution state.

As a second aspect, it is preferable that each component of the upper layer and the lower layer has a coating liquid composition that quickly separates liquid-liquid phase when mixed. Specifically, the upper layer and lower layer coating liquids have the same volume as the coating amount. It is preferable to prepare a liquid-liquid layer separation relationship when mixed at a ratio. In this case, if each component diffuses after coating, phase separation immediately occurs in the vicinity of the coating interface, and further diffusion is suppressed. Further, the phase-separated microdroplets are highly likely to merge with the original layer, and a uniform liquid-liquid interface can be maintained.
Strictly speaking, each phase (droplet) that is phase-separated becomes a phase mixed with a certain distribution ratio of solutes in the upper and lower layers, but because further phase separation is repeated with a distribution ratio that increases in purity as the concentration increases due to drying, A uniform optical interface that is not substantially problematic can be formed.
The liquid-liquid phase separation can be confirmed, for example, by placing the mixed solution in a transparent sealed container, leaving it after stirring, and visually observing whether it is separated into a two-phase liquid. Immediately after stirring, it appears as a suspension, and even if it is difficult to determine whether liquid-liquid phase separation or precipitation, it is allowed to stand for 24 hours, and in the case of liquid-liquid phase separation, it is separated into a transparent two-phase liquid. .

  As a third aspect, when the upper layer and lower layer coating solutions are mixed at the same volume ratio as the coating amount, they are mixed as a one-phase solution, but then the solution is concentrated and the liquid-liquid phase separation is performed while the solvent is reduced by 10% by mass. Preferably prepared in relation. Find a coating composition that satisfies the second relationship, especially when there is a difference in the coating amount between the upper layer and the lower layer, such as a low refractive index layer and a hard coat layer, or when there is a difference in the amount of the upper layer solute and the lower layer solute. It is difficult. In that case, a satisfactory layer and interface can also be formed by satisfying the third relationship with a view that the drying has progressed to some extent. If these conditions are satisfied, even if mixing occurs immediately after coating, liquid-liquid layer separation occurs promptly by subsequent drying, and a substantially good interface can be formed.

In the present invention, the first aspect is “a solute of a layer (lower layer) arranged on the support side among adjacent layers is insoluble or hardly soluble in a solvent of a layer (upper layer) arranged on the surface side. Means for achieving the above will be described.
The design of the lower layer solute differs depending on the upper layer solvent, but when the upper layer solvent is a solvent having a high dielectric constant such as isopropyl alcohol or acetone (17 or more), the lower layer solute preferably has a low polarity. . In order to reduce the polarity, it is preferable to introduce an unsubstituted aliphatic or aromatic linking group. For example, a compound in which dipentaerythritol is modified with caprolactone and acrylate is modified at the terminal, and a compound having an average molecular weight of 1000 to 2000 is preferable. Specific examples include KAYARAD DPCA-60 and DPCA-120 (manufactured by Nippon Kayaku Co., Ltd.). Moreover, it is also preferable to use a low-polarity copolymer in the copolymer containing a repeating unit containing an ethylenically unsaturated group and another repeating unit as in [0027] to [0028] of JP-A-2002-322430. .
On the other hand, when the upper layer solvent has a low dielectric constant (less than 17) such as a dialkyl ketone (MEK, MiBK, etc.) or an alkyl-substituted aromatic hydrocarbon (toluene), the lower layer solute preferably has a high polarity. In order to increase the polarity, it is preferable to use a compound containing a hydroxyl group in the molecule. For example, it is possible to control the polarity of the molecule by changing the degree of acetylation of diacetylcellulose having a molecular weight of about 30000, and producing a polymer that is soluble in acetone and hardly soluble in MEK with an acetylation degree of about 40%. can do. Moreover, in a copolymer containing a repeating unit containing an ethylenically unsaturated group and a repeating unit other than that as in [0027] to [0028] of JP-A-2002-322430, the copolymer component contains an amide or a hydroxyl group. It is also preferable to use one having such a highly polar functional group.

  In order to reduce the solubility in addition to the polarity of the solute, it is preferable to increase the molecular weight. The molecular weight is preferably from 800 to 100,000, and more preferably from 1,000 to 50,000. If the molecular weight is low, the solubility of the upper layer in the solvent is improved. If the molecular weight is too large, the solvent that can be dissolved when preparing the coating solution for the own layer is limited.

Next, in the present invention, a means for achieving the above-mentioned second aspect, “a coating liquid composition that allows liquid-liquid phase separation to be quickly performed when the upper layer and lower layer components are mixed” will be described.
It is effective to reduce the affinity between the upper and lower solutes, control the molecular weight, and use inorganic fine particles together.
In order to reduce the affinity between solutes, it is preferable to use a fluorine-containing compound or a silicone-containing compound as one solute. More preferably, the same molecule contains a fluorine atom and silicone, and most preferably a polymer having a molecular weight of 8000 or more.
In the present invention, the polymer that can be preferably used will be described in detail on the polymer page used in the low refractive index layer described later.

  Control of the molecular weight of the solute is effective for phase separation. The higher the molecular weight of the solutes in both layers, the lower the solubility, but with increased viscosity, it takes time to re-separate after forcible mixing due to disturbance at the interface between the two layers during coating. Tend to require. Therefore, there is a preferable region in the relationship between the molecular weights of the solutes of both layers, which are shown in Table 1 below.

  In the table, ● represents a preferred combination, ○ represents a more preferred combination, and ◎ represents the most preferred combination.

  In addition, it is effective for promoting phase separation to use oxide inorganic fine particles in at least one coating solution. The cause of the effective action of the oxide inorganic fine particles is not clear, but it is presumed that it behaves like a polymer compound having a highly polar portion such as a plurality of hydroxyl groups on the surface and changes the phase separation behavior. The oxide inorganic fine particles can be subjected to a known surface treatment for controlling the polarity of the surface. For the surface treatment of the oxide inorganic particles, for example, an organosilane compound having a polymerizable functional group and a catalyst described in WO2004 / 017105 can be used. It is also preferable to use the method described in JP-A No. 11-43319 for hydrophobizing the surface. The diameter of the oxide inorganic fine particles used for this purpose is preferably 1 to 150 nm, more preferably 3 to 100 nm. By setting it as this area | region, the coating film which is excellent in dispersion stability of microparticles | fine-particles itself, and has high transparency can be formed.

[Method of forming optical film]
The step of simultaneously applying two or more coating solutions of the present invention can be selected from a curtain coating method, an extrusion coating method (die coating method) (see US Pat. No. 2,681,294), a slide coating method, and combinations thereof. . In particular, a die coating method including one or more die coating slots and a die / slide composite coating method are preferable, but the method is not particularly limited to this method.

In order to supply the film of the present invention with high productivity, an extrusion method (die coating method) is preferably used. In particular, a slot die / slide composite coater that can be preferably used in a region with a small wet coating amount (20 cc / m ² or less) such as a hard coat layer or an antireflection layer will be described below.

[Configuration of slot die / slide composite coater]
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a slot die / slide composite coater that can be used to practice the present invention. The coater 10 in FIG. 1 is a web including a transparent support that is continuously supported by a backup roll 11 (a web made of only a transparent support may be used, or a web in which another optical layer is formed on the transparent support. ) The lower coating liquid 14 is applied to W from the slot die 13 as beads 14a. A slide type coating head is provided in the vicinity of the tip of the slot die 13 (the upper surface of the slot die 13 in FIG. 1), and the upper layer coating liquid 54 flows on the slide 51 so that the lower layer and its lower layer are simultaneously formed on the web W. Two layers are applied to form a coating film 14b.
That is, while the web W including the transparent support is continuously run while being supported by the backup roll 11, the lower layer is applied onto the transparent support using the slot die 13 and in the vicinity of the tip of the slot die. The upper layer is applied on the lower layer using a slide-type application head arranged. FIG. 1 shows a composite coater capable of forming two layers simultaneously. By providing a plurality of slide-type coating heads, a plurality of coating layers can be formed by a single coating.

  Inside the slot die 13, pockets 15 and 50 and slots 16 and 52 are formed. The pockets 15 and 50 have curved and straight cross sections, and may be, for example, substantially circular or semicircular. The pockets 15 and 50 are liquid reservoir spaces for the coating liquid extended with the cross-sectional shape in the width direction of the slot die 13, and the length of the effective extension is generally equal to or slightly longer than the coating width. is there. The supply of the coating liquid to the pockets 15 and 50 is performed from the side surface of the slot die 13 or from the center of the surface opposite to the slot openings 16a and 52a. The pockets 15 and 50 are provided with stoppers that prevent the coating liquid from leaking out.

  The slot 16 is a flow path of the coating liquid 14 from the pocket 15 to the web W, and has a cross-sectional shape in the width direction of the slot die 13 similarly to the pocket 15, and the opening 16a located on the web side is generally Using a width regulating plate (not shown), the width is adjusted to be approximately the same as the coating width. The angle between the slot tip of the slot 16 and the tangent in the web running direction of the backup roll 11 is preferably 30 ° to 90 °.

  The slot 52 is a flow path of the coating liquid 54 from the pocket 50 to the slide 51. Like the pocket 15, the slot 52 has a cross-sectional shape in the width direction of the slot die 13, and the opening 52a located on the web side is generally Using a width regulating plate (not shown), the width is adjusted to be approximately the same as the coating width.

  The tip lip 17 of the slot die 13 where the opening 16a of the slot 16 is located is tapered, and the tip is a flat portion 18 called a land. In this land 18, the upstream side in the running direction of the web W with respect to the slot 16 is referred to as an upstream lip land 18 a and the downstream side is referred to as a downstream lip land 18 b.

  The slide 51 is on the upper surface of the slot die 13, and the coating liquid flows from the pocket 50. Generally, the slide 51 is adjusted so as to have a width that is approximately the same as the coating width by using an edge guide (not shown).

The length of the slide surface is preferably in the range of 1.5 mm to 50 mm, more preferably 1.5 mm to 20 mm, and most preferably 2 mm to 10 mm. It is desirable to adjust the length of the slide surface according to the viscosity of the coating solution and the volatility of the solvent used.
The coating amount to flow from the slide type coating head is preferably 100 ml / ^{m 2} or less, more preferably 1~80ml / ^{m 2,} more preferably from 2~50ml / ^{m 2.}
In particular, when the application amount is less than 4 ml / m ² , the liquid is easily cut off on the slide surface, so it is better to adjust the flow rate to a predetermined amount after dripping at a flow rate of 5 ml / m ² or more.

In order to prevent volatilization of the coating liquid on the slide surface, it is desirable to attach a cover that covers the entire slide surface. Cover 55 and sliding 51, the cross-sectional area is 550 mm ² or less is desirable to surround the backup roll W, more preferably 250 mm ² or less, and most preferably 60 mm ² or less.
Note that slide-type coating heads are known and disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-164788.

  FIG. 2 is a view showing a cross-sectional shape of the slot die 13. The slot die in FIG. 2B is a general one, and the distance between the upstream lip land 31a and the web W of the downstream lip land 31b is equal. Reference numeral 32 denotes a pocket, and 33 denotes a slot. On the other hand, in the slot die of (A), the downstream side lip land length ILO is shortened, so that application with a wet film thickness of 20 μm or less can be performed with high accuracy. Of course, in the present invention, it is preferable to use the slot die (A).

  The running direction land length IUP of the web W of the upstream lip land 18a is not particularly limited, but is preferably used in the range of 500 μm to 1 mm. The run direction land length ILO of the web W of the downstream lip land 18b is 30 μm to 100 μm, preferably 30 μm to 80 μm, and more preferably 30 μm to 60 μm. When the land length ILO of the downstream lip is 30 μm or more, the edge of the tip lip or the chip of the land and the streaks on the coating film are prevented. Further, the setting of the wet line position on the downstream side is facilitated, and the problem that the coating liquid is likely to spread on the downstream side does not occur. It has been conventionally known that this spreading of the coating liquid on the downstream side means non-uniform wetting lines and leads to a problem of causing a defective shape such as a streak on the coating surface. On the other hand, when the land length ILO of the downstream lip is 100 μm or less, the bead formability is good, and a thin layer can be satisfactorily applied.

  Further, the downstream lip land 18b has an overbite shape closer to the web W than the upstream lip land 18a. Therefore, the degree of decompression can be lowered, and a bead suitable for thin film coating can be formed. The difference in distance between the downstream lip land 18b and the web W of the upstream lip land 18a (hereinafter referred to as the overbite length LO) is preferably 30 μm to 120 μm, more preferably 30 μm to 100 μm, most preferably 30 μm to 80 μm. It is. When the slot die 13 has an overbite shape, the gap GL between the tip lip 17 and the web W indicates the gap between the downstream lip land 18b and the web W.

  Moreover, it is also possible to install a decompression chamber (not shown) at a position not in contact with the bead 14a on the side opposite to the traveling direction side of the web W so that the decompression can be adjusted with respect to the bead 14a. As a result, the beads can be further stabilized, and, for example, even with respect to fluctuations in the web and the tip lip due to the eccentricity of the backup roll, it is possible to apply with high accuracy without unevenness.

  Two or more slot dies and slide heads may be installed as necessary. However, it is preferable to provide at least one slot die in order to form a stable bead.

  In the present invention, in order to apply two or more layers simultaneously, the wet coating amount at the time of coating can be set according to the film thickness of the layer required after drying, but the wet coating amount ratio between the upper layer and the lower layer [ The upper layer / lower layer] is preferably 1 / 0.5 to 1/100, more preferably 1/1 to 1/50, and most preferably 1/2 to 1/30. In addition to the flow ratio, the lower layer has a relatively high viscosity with respect to the upper layer, the solid content concentration is higher, and the surface tension is higher, which improves the coating surface and is effective in preventing mixing at the interface between both layers. It is.

[Material and accuracy]
The longer the length of the tip lip on the traveling direction side of the web in the web traveling direction, the more disadvantageous it is for bead formation.If this length varies between arbitrary locations in the slot die width direction, It becomes unstable. Therefore, it is preferable that the fluctuation width in the slot die width direction is within 20 μm.
Further, regarding the material of the tip lip of the slot die, if a material such as stainless steel is used, the length of the slot die tip lip in the web running direction is set to 30 to 100 μm as described above. Even within this range, the accuracy of the tip lip cannot be satisfied. Therefore, in order to maintain high processing accuracy, it is important to use a cemented carbide material as described in Japanese Patent No. 2817053. Specifically, at least the tip lip of the slot die is preferably made of a cemented carbide formed by bonding carbide crystals having an average particle size of 5 μm or less. Cemented carbides include carbide crystal particles such as tungsten carbide (hereinafter referred to as WC) bonded by a bonding metal such as cobalt, and other bonding metals include titanium, tantalum, niobium, and mixed metals thereof. Can also be used. The average particle size of the WC crystal is more preferably 3 μm or less.
In order to realize high-precision coating, the length of the land on the web traveling direction side of the tip lip and the variation in the slot die width direction of the gap with the web are also important factors. It is desirable to achieve a combination of these two factors, that is, straightness within a range in which the fluctuation range of the gap can be suppressed to some extent. Preferably, the straightness of the tip lip and the backup roll is set so that the fluctuation width of the gap in the slot die width direction is 5 μm or less.

[Application speed]
By achieving the accuracy of the backup roll and the tip lip as described above, the coating method preferably used in the present invention has high film thickness stability during high-speed coating. Furthermore, since the coating method is a pre-weighing method, it is easy to ensure a stable film thickness even during high-speed coating. With respect to a coating solution of a low coating amount, the coating method can be applied at high speed with good film thickness stability. Although application is possible by other application methods, the dip coating method inevitably causes vibration of the application liquid in the liquid receiving tank, and stepped unevenness is likely to occur. In the reverse roll coating method, stepped unevenness is likely to occur due to eccentricity and deflection of the roll related to coating. Moreover, since these coating methods are post-measuring methods, it is difficult to ensure a stable film thickness. From the viewpoint of productivity, it is preferable to apply the die coating method at 25 m / min or more. Further, in order to prevent the coating liquid from being mixed at the bead portion during coating, it is preferable to increase the coating speed, and there is an upper limit to the coating speed to impart bead stability. The coating speed region is preferable. That is, the coating speed is preferably 5 to 100 m / min, more preferably 10 to 80 m / min, and most preferably 20 to 60 m / min.

[Drying process]
The film of the present invention is preferably applied on a support directly or via another layer and then conveyed by a web to a heated zone to dry the solvent.
Various knowledges can be used as a method for drying the solvent. Specific examples include JP-A Nos. 2001-286817, 2001-314798, 2003-126768, 2003-315505, and 2004-34002.
The temperature of the drying zone is preferably 25 ° C. to 140 ° C., the first half of the drying zone is preferably a relatively low temperature, and the latter half is preferably a relatively high temperature. When the evaporation rate of the solvent is the same, it is preferable that the first half of the drying is relatively low temperature because mixing of the interface of the coated layer is suppressed in order to reduce diffusion of solute molecules and coexisting fine particles. . Moreover, it is preferable that the temperature of the latter half of drying is below the temperature at which components other than the solvent contained in the coating composition of each layer start to volatilize. For example, some of the commercially available photo radical generators used in combination with ultraviolet curable resins volatilize around several tens of percent within a few minutes in warm air at 120 ° C. Some acrylate monomers and the like undergo volatilization in warm air at 100 ° C. In such a case, it is preferable that it is below the temperature at which components other than the solvent contained in the coating composition of each layer start to volatilize as described above.

Moreover, the dry wind after apply | coating the coating composition of each layer on a support body has the wind speed of the coating-film surface of 0.1-2 m / sec while the solid content concentration of the said coating composition is 1-50%. It is preferable to be in the range in order to prevent drying unevenness.
Moreover, after apply | coating the coating composition of each layer on a support body, the temperature difference of the conveyance roll which contacts the surface opposite to the coating surface of a support body in a drying zone, and a support body is 0 to 20 degreeC or less. Then, the drying nonuniformity by the heat transfer nonuniformity on a conveyance roll can be prevented, and it is preferable.

[Curing process]
After drying the solvent, the film of the present invention can be passed through a zone where the coating film is cured by ionizing radiation and / or heat on the web to cure the coating film.
The ionizing radiation species in the present invention is not particularly limited, and is appropriately selected from ultraviolet rays, electron beams, near ultraviolet rays, visible light, near infrared rays, infrared rays, X-rays and the like according to the type of curable composition forming the film. Although it can be selected, ultraviolet rays and electron beams are preferred, and ultraviolet rays are particularly preferred because they are easy to handle and high energy can be easily obtained.
As the ultraviolet light source for photopolymerizing the ultraviolet reactive compound, any light source that generates ultraviolet light 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. An ArF excimer laser, a KrF excimer laser, an excimer lamp, synchrotron radiation, or the like can also be used. Among these, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp can be preferably used.

  Moreover, an electron beam can be used similarly. As an electron beam, 50 to 1000 keV, preferably 100 to 100, emitted from various electron beam accelerators such as a cockroft Walton type, a bandegraph type, a resonance transformation type, an insulated core transformer type, a linear type, a dynamitron type, and a high frequency type. An electron beam having an energy of 300 keV can be given.

Irradiation conditions vary depending on each lamp, but the amount of irradiation light is preferably 10 mJ / cm ² or more, more preferably 50 mJ / cm ^{2 to} 10000 mJ / cm ² , and particularly preferably 50 mJ / cm ^{2 to} 2000 mJ / cm ^2. It is. At that time, the irradiation distribution in the width direction of the web is preferably 50 to 100%, more preferably 80 to 100%, including both ends with respect to the central maximum irradiation.

In the present invention, in particular, at least one layer laminated on the support is irradiated with ionizing radiation and heated at a film surface temperature of 60 ° C. or more for 0.5 seconds or more from the start of ionizing radiation irradiation, It is preferable to harden by the process of irradiating with ionizing radiation in an atmosphere of 10% by volume or less.
It is also preferable to heat in an atmosphere having an oxygen concentration of 3% by volume or less simultaneously and / or continuously with ionizing radiation irradiation.
In particular, it is preferable that the low refractive index layer which is the outermost layer and has a small film thickness is cured by this method. The curing reaction is accelerated by heat, and a film having excellent physical strength and chemical resistance can be formed.

[Formation method]
In the present invention, it is preferable that a plurality of coating liquids are simultaneously coated, dried and cured on a transparent support by a single coating to form a plurality of optical layers such as a hard coat layer and an antireflection layer. Thereby, the coating, drying and curing zones can be greatly reduced, which is preferable in terms of productivity and cost. In addition, when forming three or more layers, even if not all layers can be applied simultaneously, the manufacturing method of the present invention is used, and it is sufficient to install two-layer simultaneous application stations continuously. Production benefits can be obtained. For example, when four layers of a hard coat layer, a medium refractive index layer, a high refractive index layer, and a low refractive index layer are formed on a transparent support, the hard coat layer and the medium refractive index layer are formed simultaneously, By forming the surface layer of the high refractive index layer and the low refractive index layer simultaneously, it is only necessary to arrange two sets of coating stations and drying / curing zones between the time when the transparent support is fed and the time of winding. That is a big effect.

[Configuration of antireflection film]
The optical film formed by the production method of the present invention is not particularly limited, and examples thereof include an antireflection film, a light diffusion film, and an antiglare film. The production method of the present invention is particularly suitable for an antireflection film.
Hereinafter, a configuration example of the antireflection film will be described with reference to the drawings.

FIG. 3 is a cross-sectional view schematically showing a layer structure of a multilayer antireflection film having excellent antireflection performance. It has a layer structure in the order of a transparent support 1, a layer having hard coat properties (hereinafter, hard coat layer) 2, a medium refractive index layer 3, a high refractive index layer 4, and a low refractive index layer (outermost layer) 5. The transparent support 1, the medium refractive index layer 3, the high refractive index layer 4, and the low refractive index layer 5 desirably have refractive indexes that satisfy the following relationship.
Refractive index of high refractive index layer> refractive index of medium refractive index layer> refractive index of transparent support> refractive index of low refractive index layer The layer structure as shown in FIG. 3 is described in JP-A-59-50401. As shown in the graph, the intermediate refractive index layer satisfies the following formula (I), the high refractive index layer satisfies the following formula (II), and the low refractive index layer satisfies the following formula (III). It is preferable at the point which can produce the antireflection film which has.

Formula (I)
(Hλ / 4) × 0.7 <n3d3 <(hλ / 4) × 1.3

  In formula (I), h is a positive integer (generally 1, 2 or 3), n3 is the refractive index of the medium refractive index layer, and d3 is the layer thickness (nm) of the medium refractive index layer. . λ is the wavelength (nm) of visible light, and is a value in the range of 380 to 680 nm.

Formula (II)
(Iλ / 4) × 0.7 <n4d4 <(iλ / 4) × 1.3

  In formula (II), i is a positive integer (generally 1, 2 or 3), n4 is the refractive index of the high refractive index layer, and d4 is the layer thickness (nm) of the high refractive index layer. . λ is the wavelength (nm) of visible light, and is a value in the range of 380 to 680 nm.

Formula (III)
(Jλ / 4) × 0.7 <n5d5 <(jλ / 4) × 1.3

  In Formula (III), j is a positive odd number (generally 1), n5 is the refractive index of the low refractive index layer, and d5 is the layer thickness (nm) of the low refractive index layer. λ is the wavelength (nm) of visible light, and is a value in the range of 380 to 680 nm.

In the layer configuration as shown in FIG. 3, it is particularly preferable that the middle refractive index layer satisfies the following formula (IV), the high refractive index layer satisfies the following formula (V), and the low refractive index layer satisfies the following formula (VI). .
Here, λ is 500 nm.

Formula (IV)
(Λ / 4) × 0.80 <n3d3 <(λ / 4) × 1.00
Formula (V)
(Λ / 2) × 0.75 <n4d4 <(λ / 2) × 0.95
Formula (VI)
(Λ / 4) × 0.95 <n5d5 <(λ / 4) × 1.05

  FIG. 4 is a cross-sectional view schematically showing another layer configuration of a multilayer antireflection film having excellent antireflection performance. The transparent support 1, the hard coat layer 2, and the low refractive index layer (outermost layer) 3 are arranged in this order. The hard coat layer can be provided with fine irregularities on the surface to impart an antiglare function.

  FIG. 5 is a cross-sectional view schematically showing the layer structure of an antiglare antireflection film when fine particles are used in the hard coat layer as means for providing fine irregularities on the surface of the hard coat layer. It has a layer structure in the order of a transparent support 1, an antiglare hard coat layer 2, and a low refractive index layer (outermost layer) 3. The fine particles are preferably translucent.

The integrated reflectance of the antireflection film of the present invention is preferably 3% or less, more preferably 1.5% or less, and particularly preferably 0.5% or less. The specular reflectance shows a value almost equal to the integrated reflectance in a glossy film having no surface irregularities, and the preferred range is also the same. An anti-glare film with irregularities on the surface can effectively reduce the specular reflectivity and adjust it in the above preferred direction as long as there are no other problems such as blackening and whitening. You can also.
In order to obtain a low reflectance, layers having different refractive indexes are laminated. Therefore, if the refractive index and the film thickness are not adjusted, the color is strong, and there may be a problem in quality. The color of the antireflection film of the present invention is preferably | a ^* | ≦ 10, | b ^* | ≦ 10, particularly preferably | a ^* | ≦ 7, | b ^* | ≦ 7, | a ^* | ≦ 5, | B ^* | ≦ 5 is more preferable, and | a ^* | ≦ 4 and | b ^* | ≦ 4 are particularly preferable.

[Transparent support]
The support for the film of the present invention is not particularly limited, such as a transparent resin film, a transparent resin plate, a transparent resin sheet, and transparent glass. Transparent resin films include cellulose acylate films (for example, cellulose triacetate film (refractive index 1.48), cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film), polyethylene terephthalate film, polyethersulfone. Films, polyacrylic resin films, polyurethane resin films, polyester films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyetherketone films, (meth) acrylonitrile films, and the like can be used.
Although the thickness of a support body can use the thing of about 25 micrometers-1000 micrometers normally, Preferably it is 25 micrometers-200 micrometers, It is more preferable that it is 30 micrometers-150 micrometers, It is further more preferable that it is 30-90 micrometers.
Any width of the support can be used, but from the viewpoint of handling, yield, and productivity, a width of 100 to 5000 mm is usually used, preferably 800 to 3000 mm, and preferably 1000 to 2000 mm. More preferably.
The surface of the support is preferably smooth, and the average roughness Ra is preferably 1 μm or less, preferably 0.0001 to 0.5 μm, and 0.001 to 0.1 μm. Is more preferable.
The transparent support is preferably a plastic film. Examples of the plastic film include cellulose esters (eg, triacetylcellulose, diacetylcellulose, propionylcellulose, butyrylcellulose, acetylpropionylcellulose, nitrocellulose) and polyolefins (eg, polypropylene, polyethylene, polymethylpentene, triacetylcellulose, Polyolefin is preferable for polarizing plates because of its low retardation and high optical uniformity, and triacetyl cellulose is particularly preferable when used for liquid crystal display devices.

[Resin composition]
In the present invention, a resin composition such as a reactive monomer or a reactive oligomer can be used as a component of each layer. The resin composition can be formed by a crosslinking reaction or a polymerization reaction of an ionizing radiation curable compound. That is, the resin composition is a coating composition containing an ionizing radiation curable monomer or oligomer, and is formed on a transparent support by coating the reactive monomer or oligomer with a crosslinking reaction or a polymerization reaction. can do.
The functional group of the ionizing radiation curable reactive monomer or oligomer is preferably a light, electron beam, or radiation polymerizable group, and among them, a photopolymerizable functional group is preferable.
Examples of the photopolymerizable functional group include unsaturated polymerizable functional groups such as a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, a (meth) acryloyl group is preferable.
In particular, it is preferable to use a polymerizable monomer and / or oligomer for forming a layer other than the outermost layer. The polymerizable monomer or oligomer used for forming a layer other than the outermost layer is a polyfunctional monomer or polyfunctional oligomer having two or more functional groups in one molecule, which improves film strength and adhesion. Is preferable.
Two or more kinds of reactive monomers contained in one layer may be used in combination. In this case, at least one kind is preferably a polyfunctional monomer.

As a specific example of a photopolymerizable polyfunctional monomer having a photopolymerizable functional group,
(Meth) acrylic acid diesters of alkylene glycol such as neopentyl glycol acrylate, 1,6-hexanediol (meth) acrylate, propylene glycol di (meth) acrylate;
(Meth) acrylic acid diesters of polyoxyalkylene glycols such as triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate;
(Meth) acrylic acid diesters of polyhydric alcohols such as pentaerythritol di (meth) acrylate;
(Meth) acrylic acid diesters of ethylene oxide or propylene oxide adducts such as 2,2-bis {4- (acryloxy · diethoxy) phenyl} propane and 2-bis {4- (acryloxy · polypropoxy) phenyl} propane ;
Etc.

  Furthermore, epoxy (meth) acrylates, urethane (meth) acrylates, and polyester (meth) acrylates are also preferably used as the photopolymerizable polyfunctional monomer.

  Among these, esters of polyhydric alcohol and (meth) acrylic acid are preferable. More preferably, a polyfunctional monomer having 3 or more (meth) acryloyl groups in one molecule is preferable. Specifically, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, 1,2,4-cyclohexanetetra (meth) acrylate, pentaglycerol triacrylate, pentaerythritol tetra (meth) acrylate, penta Erythritol tri (meth) acrylate, (di) pentaerythritol triacrylate, (di) pentaerythritol pentaacrylate, (di) pentaerythritol tetra (meth) acrylate, (di) pentaerythritol hexa (meth) acrylate, tripentaerythritol triacrylate , Tripentaerythritol hexatriacrylate and the like. In the present specification, “(meth) acrylate”, “(meth) acrylic acid”, and “(meth) acryloyl” represent “acrylate or methacrylate”, “acrylic acid or methacrylic acid”, and “acryloyl or methacryloyl”, respectively. .

As the monomer binder, monomers having different refractive indexes can be used to control the refractive index of each layer. Examples of particularly high refractive index monomers include bis (4-methacryloylthiophenyl) sulfide, vinyl naphthalene, vinyl phenyl sulfide, 4-methacryloxyphenyl-4′-methoxyphenyl thioether, and the like.
Further, for example, dendrimers described in JP-A-2005-76005 and JP-A-2005-36105, and norbornene ring-containing monomers as described in JP-A-2005-60425 can also be used.

It is preferable to use a photopolymerization initiator for the polymerization reaction of the photopolymerizable monomer. As the photopolymerization initiator, a photoradical polymerization initiator and a photocationic polymerization initiator are preferable, and a photoradical polymerization initiator is particularly preferable.
Examples of the photo radical polymerization initiator include acetophenones, benzophenones, Michler's benzoylbenzoate, α-amyloxime ester, tetramethylthiuram monosulfide, and thioxanthones.

  As a commercially available photo radical polymerization initiator, Kayacure (DETX-S, BP-100, BDMK, CTX, BMS, 2-EAQ, ABQ, CPTX, EPD, ITX, QTX, BTC, manufactured by Nippon Kayaku Co., Ltd. MCA, etc.), Irgacure (651, 184, 500, 907, 369, 1173, 2959, 4265, 4263, etc.) manufactured by Ciba Geigy Co., Ltd., Esacure (KIP100F, KB1, EB3, BP, X33, KT046) manufactured by Sartomer , KT37, KIP150, TZT) and the like.

In particular, photocleavable photoradical polymerization initiators are preferred. The photocleavable photoradical polymerization initiator is described in the latest UV curing technology (P.159, issuer; Kazuhiro Takashiro, publisher; Technical Information Association, Inc., published in 1991).
Examples of commercially available photocleavable photoradical polymerization initiators include Irgacure (651, 184, 907) manufactured by Ciba Geigy Japan.

It is preferable to use a photoinitiator in the range of 0.1-15 mass parts with respect to 100 mass parts of monomers, More preferably, it is the range of 1-10 mass parts.
In addition to the photopolymerization initiator, a photosensitizer may be used. Specific examples of the photosensitizer include n-butylamine, triethylamine, tri-n-butylphosphine, Michler's ketone and thioxanthone.
Examples of commercially available photosensitizers include Kayacure (DMBI, EPA) manufactured by Nippon Kayaku Co., Ltd.
The photopolymerization reaction is preferably performed by ultraviolet irradiation after the coating layer is formed and dried.

[Coating solvent]
The solvent used in the coating composition for forming each layer of the present invention is based on the premise that each component can be dissolved or dispersed and that the above-mentioned relationship with solubility and phase separation with adjacent solutes is satisfied. In addition, various solvents selected from the viewpoints of being easy to form a uniform surface in the coating process and the drying process, ensuring liquid storage stability, having an appropriate saturated vapor pressure, and the like can be used.
Two or more kinds of solvents can be mixed and used. In particular, from the viewpoint of drying load, it is preferable that a solvent having a boiling point of 100 ° C. or less at normal pressure and room temperature as a main component and a small amount of solvent having a boiling point exceeding 100 ° C. is included for adjusting the drying speed.

  Examples of the solvent having a boiling point of 100 ° C. or lower include hydrocarbons such as hexane (boiling point 68.7 ° C.), heptane (98.4 ° C.), cyclohexane (80.7 ° C.), benzene (80.1 ° C.), Halogenated carbonization such as dichloromethane (39.8 ° C), chloroform (61.2 ° C), carbon tetrachloride (76.8 ° C), 1,2-dichloroethane (83.5 ° C), trichloroethylene (87.2 ° C) Hydrogens, diethyl ether (34.6 ° C), diisopropyl ether (68.5 ° C), dipropyl ether (90.5 ° C), ethers such as tetrahydrofuran (66 ° C), ethyl formate (54.2 ° C), Esters such as methyl acetate (57.8 ° C.), ethyl acetate (77.1 ° C.), isopropyl acetate (89 ° C.), acetone (56.1 ° C.), 2-butanone (methyl ether) Ketones such as Luketone, 79.6 ° C, methanol (64.5 ° C), ethanol (78.3 ° C), 2-propanol (82.4 ° C), 1-propanol (97.2 ° C), etc. Alcohols, cyano compounds such as acetonitrile (81.6 ° C.), propionitrile (97.4 ° C.), carbon disulfide (46.2 ° C.), and the like. Of these, ketones and esters are preferable, and ketones are particularly preferable. Among the ketones, 2-butanone is particularly preferable.

  Examples of the solvent having a boiling point exceeding 100 ° C. include octane (125.7 ° C.), toluene (110.6 ° C.), xylene (138 ° C.), tetrachloroethylene (121.2 ° C.), chlorobenzene (131.7 ° C.), Dioxane (101.3 ° C.), dibutyl ether (142.4 ° C.), isobutyl acetate (118 ° C.), cyclohexanone (155.7 ° C.), 2-methyl-4-pentanone (same as MIBK, 115.9 ° C.), Examples thereof include 1-butanol (117.7 ° C.), N, N-dimethylformamide (153 ° C.), N, N-dimethylacetamide (166 ° C.), dimethyl sulfoxide (189 ° C.) and the like. Cyclohexanone and 2-methyl-4-pentanone are preferable.

Hereinafter, the layer which comprises the optical film of this invention, especially an antireflection film is demonstrated.
[Hard coat layer]
In order to give the physical strength of the film to the film of the present invention, a hard coat layer is preferably provided on one surface of the transparent support.

  The refractive index of the hard coat layer in the present invention is preferably in the range of 1.48 to 1.75, more preferably 1.49 to 1, from the optical design for obtaining an antireflection film. .65, and more preferably 1.50 to 1.55. In the present invention, the refractive index of the hard coat layer is unfavorable whether it is larger or smaller than this range from the viewpoint of reflectance, color, unevenness and cost.

From the viewpoint of imparting sufficient durability and impact resistance to the film, the thickness of the hard coat layer is usually about 0.5 μm to 50 μm, preferably 1 μm to 30 μm, more preferably 2 μm. ˜20 μm, most preferably 3 μm to 15 μm. If the hard coat layer is too thick, it is not preferable from the viewpoint of curling, productivity and cost.
Further, the strength of the hard coat layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test. More preferably, it is 5H or more.
Furthermore, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of an ionizing radiation curable compound. For example, it can be formed by coating a coating composition containing the above-mentioned ionizing radiation-curable monomer or oligomer on a transparent support and causing the reactive monomer or reactive oligomer to undergo a crosslinking reaction or a polymerization reaction.
The functional group of the ionizing radiation-curable reactive monomer or reactive oligomer is preferably a light, electron beam, or radiation polymerizable functional group, and among them, a photopolymerizable functional group is preferable.
Examples of the photopolymerizable functional group include unsaturated polymerizable functional groups such as a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, a (meth) acryloyl group is preferable.

The hard coat layer has an average particle size of 1.0 to 20.0 μm, preferably 1.5 to 15.0 μm, more preferably 1.5 to 10 μm for the purpose of imparting internal scattering properties and antiglare properties. The light-transmitting particles, for example, inorganic compound particles or resin particles may be contained. The content of the translucent particles is preferably 0 to 66 wt% in the previous solid content of the hard coat layer. 1 to 50 wt% is more preferable, and 3 to 30% is more preferable.
The average particle diameter of the translucent particles can be calculated by measuring an electron micrograph of the particles by a Coulter counter method.

In order to control the refractive index of the hard coat layer, a high refractive index or low refractive index monomer, inorganic fine particles, or both can be added to the binder of the hard coat layer. The inorganic fine particles are not particularly limited, but inorganic fine particles mainly composed of one or more of silicon dioxide, aluminum oxide, zirconia oxide, titanium oxide, zinc oxide, antimony oxide, tin oxide, indium oxide and the like can be preferably used. . The average particle size of the inorganic fine particles is desirably 100 nm or less, more desirably 1 to 80 nm, still more desirably 2 to 50 nm, and particularly desirably 5 to 30 nm. If the particle size is too large, the haze increases, and if the particle size is too small, the particles easily aggregate and are difficult to disperse. In addition to the effect of controlling the refractive index, the inorganic fine particles also have an effect of suppressing curing shrinkage due to a crosslinking reaction. In the present invention, after the hard coat layer is formed, a polymer produced by polymerizing the monomer and / or oligomer, and when containing inorganic fine particles, the binder contains inorganic fine particles dispersed therein. Called.
The average particle size of the inorganic fine particles can be measured by a coal counter method.

The haze of the hard coat layer varies depending on the function imparted to the antireflection film.
In addition to the function of suppressing the reflectance of the surface, when the anti-glare function is imparted by the surface scattering of the hard coat layer, the surface haze (the value obtained by subtracting the internal haze value from the total haze value. The internal haze value is the film surface). Is preferably 0.3% to 20%, and more preferably 0.4% to 10%. More preferably, it is 0.6% to 5%.
Since the antireflection film of the present invention has high antireflection performance by suppressing the reflectance of the surface, the antiglare of the hard coat layer is maintained in order to maintain the sharpness of the image and suppress white blur in a bright room. It is also preferable to use without adding a function from the viewpoint of obtaining good image quality.

In addition, when the hard coat layer contains translucent particles to give internal scattering, the preferred range of internal haze varies depending on the purpose, but due to internal scattering, liquid crystal panel patterns, color unevenness, luminance unevenness, glare, etc. are observed. When making it difficult or providing the function of expanding the viewing angle by scattering, the internal haze value is preferably 10% to 90%, particularly preferably 15% to 80%, and more preferably 20% to 70%. Most preferred is 20 to 40%. On the other hand, when importance is attached to the front contrast, 0% to 30% is preferable, more preferably 1% to 20%, and most preferably 1% to 10%.
The film of the present invention can freely set surface haze and internal haze according to the purpose.

  Moreover, about the surface uneven | corrugated shape of a hard-coat layer, it is preferable that centerline average roughness (Ra) shall be 0.30 micrometer or less. Ra is more preferably 0.01 to 0.20 μm, and further preferably 0.02 to 0.12 μm or less. When Ra is large, there are problems such as white blurring caused by surface scattering and uniformity of the layer formed on the hard coat layer. The average mountain-valley distance (Sm) is preferably 20 to 200 μm. More preferably, it is 40-160 micrometers, More preferably, it is 50-130 micrometers. In the film of the present invention, the surface unevenness of the hard coat layer is dominant to the surface unevenness of the film, and the center line average roughness of the antireflection film is adjusted by adjusting the center line average roughness of the hard coat layer. It can be set as the said range.

  In order to maintain the sharpness of the image, it is preferable to adjust the clarity of the transmitted image in addition to adjusting the uneven shape of the surface. The transmitted image definition of the antireflection film is preferably 60% or more. The transmitted image clarity is generally an index indicating the degree of blurring of an image reflected through a film, and the larger this value, the clearer and better the image viewed through the film. The transmitted image definition is preferably 70% or more, and more preferably 80% or more.

[High refractive index layer, medium refractive index layer]
The film of the present invention can be provided with a high refractive index layer and a medium refractive index layer to enhance antireflection properties.
In the following specification, the high refractive index layer and the medium refractive index layer may be collectively referred to as a high refractive index layer. In the present invention, “high”, “medium”, and “low” in the high refractive index layer, the medium refractive index layer, and the low refractive index layer represent the relative refractive index relationship between the layers. In terms of the relationship with the transparent support, the refractive index preferably satisfies the relationship of transparent support> low refractive index layer, high refractive index layer> transparent support.
In the present specification, the high refractive index layer, the middle refractive index layer, and the low refractive index layer may be collectively referred to as an antireflection layer.

  In order to construct an antireflection film by constructing a low refractive index layer on a high refractive index layer, the refractive index of the high refractive index layer is preferably 1.55 to 2.20, more preferably It is 1.60 to 2.00, more preferably 1.65 to 1.90, and most preferably 1.70 to 1.85. The higher the refractive index of the high refractive index layer, the easier it is to reduce the reflectance. However, the color becomes stronger and the amount of inorganic fine particles in the high refractive index layer increases, so that the layer becomes brittle and haze increases. In the present invention, it is preferable to adjust to the above range.

  When an antireflection film is formed by coating a medium refractive index layer, a high refractive index layer, and a low refractive index layer in order from the support, the refractive index of the medium refractive index layer is higher than the refractive index of the low refractive index layer. It adjusts so that it may become a value between the refractive indexes of a refractive index layer. The refractive index of the middle refractive index layer is preferably 1.55 to 1.80, and the refractive index difference between the low refractive index layer and / or the high refractive index layer is preferably 0.08 or more, and 0.10 or more. Is particularly preferred.

  For the binder of the high refractive index layer and the medium refractive index layer used in the present invention (for example, the ionizing radiation-curable monomer or oligomer, and those described in the section of the hard coat layer can be used), the hard coat layer For the purpose of controlling the refractive index, it is preferable to add high refractive index inorganic fine particles. The high refractive index inorganic fine particles are not particularly limited, but inorganic fine particles mainly composed of one or more of aluminum oxide, zirconium oxide, titanium oxide, zinc oxide, antimony oxide, tin oxide, indium oxide and the like can be preferably used. . Particularly preferred are inorganic fine particles mainly composed of zirconium oxide (refractive index: approximately 2.2) or titanium oxide (refractive index: approximately 2.5). The refractive index of the inorganic fine particles is preferably 1.9 or more, particularly preferably 2.0 or more. The average particle size of the inorganic fine particles is desirably 100 nm or less, more desirably 1 to 80 nm, still more desirably 2 to 50 nm, and particularly desirably 5 to 30 nm. If the particle size is too large, the haze increases, and if the particle size is too small, the particles tend to aggregate and are difficult to disperse.

  The inorganic fine particles used in the high refractive index layer and the medium refractive index layer are preferably used for forming the high refractive index layer and the medium refractive index layer in a dispersion state. Inorganic particles used in the present invention are dispersed in a dispersion liquid or coating liquid, or are used in plasma discharge treatment or corona discharge treatment in order to stabilize dispersion, or to improve affinity and binding properties with a binder component. A physical surface treatment, a chemical surface treatment with a surfactant, a coupling agent or the like may be performed.

Furthermore, it is preferable to cause the binder of the high refractive index layer and the medium refractive index layer to undergo a crosslinking reaction or a polymerization reaction with the dispersant simultaneously with or after the coating of the layer.
The binder of the high refractive index layer and the medium refractive index layer thus prepared includes, for example, the above-mentioned preferable dispersant and an ionizing radiation curable monomer or oligomer cross-linked or polymerized, and the binder is an anion of the dispersant. It becomes a form in which a sex group is incorporated. Furthermore, the binder of the high refractive index layer and the medium refractive index layer has a function in which the anionic group maintains the dispersion state of the inorganic particles, and the crosslinked or polymerized structure imparts a film forming ability to the binder and contains inorganic particles. To improve the physical strength, chemical resistance and weather resistance of the high refractive index layer and medium refractive index layer.

  The binder of the high refractive index layer is added in an amount of 5 to 80% by mass based on the solid content of the coating composition of the layer.

The content of inorganic particles in the high refractive index layer is preferably 10 to 90% by mass, more preferably 15 to 80% by mass, and particularly preferably 30 to 75% by mass with respect to the mass of the high refractive index layer. . Two or more inorganic particles may be used in combination in the high refractive index layer.
The high refractive index layer contains an ionizing radiation curable compound containing an aromatic ring, an ionizing radiation curable compound containing a halogenated element other than fluorine (for example, Br, I, Cl, etc.), and atoms such as S, N, P, etc. A binder obtained by a crosslinking or polymerization reaction such as an ionizing radiation curable compound can also be preferably used.

  The film thickness of the high refractive index layer can be appropriately designed depending on the application. When using a high refractive index layer as an optical interference layer described later, the thickness is preferably 30 to 200 nm, more preferably 50 to 170 nm, and particularly preferably 60 to 150 nm.

The haze of the high refractive index layer is preferably as low as possible. It is preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less.
The high refractive index layer is preferably constructed directly on the transparent support or via another layer.

[Low refractive index layer]
In order to reduce the reflectance, it is necessary to use a low refractive index layer as the outermost layer of the antireflection film of the present invention.

The refractive index of the low refractive index layer is preferably 1.20 to 1.46, more preferably 1.25 to 1.46, and particularly preferably 1.30 to 1.46.
The thickness of the low refractive index layer is preferably 50 to 200 nm, and more preferably 70 to 100 nm. The haze of the low refractive index layer is preferably 3% or less, more preferably 2% or less, and most preferably 1% or less. The strength after forming the low refractive index layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test under a 500 g load. More preferably, it is 5H or more.
In order to improve the antifouling performance of the optical film, it is preferable that the contact angle of the surface with respect to water is 90 degrees or more. More preferably, it is 95 degrees or more, and particularly preferably 100 degrees or more. The dynamic friction coefficient of the surface of the low refractive index layer is preferably 0.03 to 0.30.

  In the composition for forming the low refractive index layer, any of thermosetting or ionizing radiation curable monomers, oligomers and polymers can be used as the resin component. (A) Thermosetting type or ionizing radiation curable type It is particularly preferable to use a fluorine-containing compound (fluorine-containing polymer, fluorine-containing sol-gel material, etc.). Moreover, although it is preferable to contain (B) inorganic particle and / or (C) organosilane compound, it is especially preferable to contain all three types (A) to (C).

As the fluorine-containing compound, those having a silicone structural unit in the molecule are preferred from the viewpoint of antifouling properties and durability.
The fluorine-containing compound is preferably contained in the low refractive index layer coating solution in an amount of 30% by mass to 90% by mass, and more preferably 30% by mass to 70% by mass, as a film forming component of the layer.

  In the present invention, a fluorine-containing polymer is preferably used as a binder for the low refractive index layer from the viewpoint of chemical resistance and productivity. As the fluorine-containing polymer, either a thermosetting type or an ionizing radiation curable type can be used. In the present invention, it is preferable to form the high refractive index layer and the low refractive index layer simultaneously. In order to increase the affinity and binding properties with the high refractive index layer component and to improve the scratch resistance of the antireflection film, the fluoropolymer is particularly preferably an ionizing radiation curable type. When using a thermosetting type, it is preferable to use simultaneously the binder component which has both a thermosetting type and ionizing-radiation-curable type crosslinkable group.

Hereinafter, preferred embodiments of the fluorine-containing compound having a crosslinkable or polymerizable functional group will be described.
Examples of the fluorine-containing compound having a crosslinkable or polymerizable functional group include a copolymer of a fluorine-containing monomer and a monomer having a crosslinkable or polymerizable functional group. Examples of the fluorine-containing monomer include fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc.) (meta ) Acrylic acid partial or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (manufactured by Osaka Organic Chemicals) and M-2020 (manufactured by Daikin)), fully or partially fluorinated vinyl ethers, and the like.

  As an example of the monomer for imparting a crosslinkable group, a (meth) acrylate monomer having a crosslinkable functional group in the molecule in advance such as glycidyl methacrylate can be exemplified. In another embodiment, after synthesizing a fluorinated copolymer using a monomer having a functional group such as a hydroxyl group, the monomer is further modified to introduce a crosslinkable or polymerizable functional group by modifying the substituent. It is. These monomers include (meth) acrylate 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, etc.) Is mentioned. The latter embodiment is disclosed in Japanese Patent Laid-Open Nos. 10-25388 and 10-147739.

The fluorine-containing copolymer may contain a copolymerizable component as appropriate from the viewpoints of solubility, dispersibility, coating property, antifouling property, antistatic property and the like. In particular, for imparting antifouling properties and slipperiness, it is preferable to introduce silicone, and it can be introduced into both the main chain and the side chain.
The polysiloxane partial structure introduction method to the main chain is, for example, an azo group-containing polysiloxane amide described in JP-A-6-93100 (VPS-0501, 1001 (trade name; Wako Pure Chemical Industries, Ltd. And a method using a polymer-type initiator such as a company)). Further, the method of introducing into the side chain is, for example, as described in J. Appl. Polym. Sci. 2000, 78, 1955, JP-A-56-28219, etc. For example, a silaplane series (manufactured by Chisso Corporation) can be synthesized by a method of introducing a polymer reaction or a method of polymerizing a polysiloxane-containing silicon macromer, and both methods can be preferably used.

As described in JP 2000-17028 A, a curing agent having a polymerizable unsaturated group may be used in combination with the above polymer. Moreover, combined use with the compound which has a fluorine-containing polyfunctional polymerizable unsaturated group as described in Unexamined-Japanese-Patent No. 2002-145952 is also preferable. Examples of the compound having a polyfunctional polymerizable unsaturated group include the above-described monomers having two or more ethylenically unsaturated groups. Moreover, the hydrolysis-condensation product of the organosilane described in Unexamined-Japanese-Patent No. 2004-170901 is also preferable, and the hydrolysis-condensation product of the organosilane containing a (meth) acryloyl group is especially preferable.
These compounds are particularly preferred because they have a large combined effect for improving scratch resistance, particularly when a compound having a polymerizable unsaturated group is used in the polymer body.

  When the polymer itself does not have sufficient curability, necessary curability can be imparted by blending a crosslinkable compound. For example, when the polymer body contains a hydroxyl group, various amino compounds are preferably used as the curing agent. The amino compound used as the crosslinkable compound is, for example, a compound containing one or both of a hydroxyalkylamino group and an alkoxyalkylamino group in total, specifically, for example, a melamine compound, Examples include urea compounds, benzoguanamine compounds, glycoluril compounds, and the like. For curing these compounds, an organic acid or a salt thereof is preferably used.

  Specific examples of these fluoropolymers are described in JP2003-222702A, JP2003-183322A, and the like.

[Anti-fouling agent]
For the purpose of imparting antifouling properties, water resistance, chemical resistance, slipperiness, etc., to the film of the present invention, particularly the uppermost layer of the film, a known silicone-based or fluorine-based antifouling agent, slipping agent, etc. It is preferable to add appropriately.
When these additives are added, it is preferably added in the range of 0.01 to 20% by mass of the total solid content of the low refractive index layer, more preferably in the range of 0.05 to 10% by mass. The case is particularly preferably 0.1 to 7% by mass. The antifouling agent is also preferably used as a structural unit in the molecule of the fluorine-containing compound.

  Preferable examples of the silicone compound include those having a substituent at the terminal and / or side chain of a compound chain containing a plurality of dimethylsilyloxy units as repeating units. The compound chain containing dimethylsilyloxy as a repeating unit may contain a structural unit other than dimethylsilyloxy. The substituents may be the same or different, and a plurality of substituents are preferable. Examples of preferred substituents include acryloyl group, methacryloyl group, vinyl group, aryl group, cinnamoyl group, epoxy group, oxetanyl group, hydroxyl group, fluoroalkyl group, polyoxyalkylene group, carboxyl group, amino group and the like. It is done. Although there is no restriction | limiting in particular in molecular weight, It is preferable that it is 100,000 or less, It is more preferable that it is 50,000 or less, It is especially preferable that it is 3000-30000, It is most preferable that it is 10,000-20000. Although there is no restriction | limiting in particular in silicone atom content of a silicone type compound, it is preferable that it is 18.0 mass% or more, it is especially preferable that it is 25.0-37.8 mass%, and 30.0-37.0. Most preferably, it is mass%. Examples of preferable silicone compounds include X-22-174DX, X-22-2426, X-22-164B, X22-164C, X-22-170DX, X-22-176D, X, manufactured by Shin-Etsu Chemical Co., Ltd. -22-1821 (named above), Chisso Corporation, FM-0725, FM-7725, FM-4421, FM-5521, FM6621, FM-1121, Gelest DMS-U22, RMS-033, RMS- 083, UMS-182, DMS-H21, DMS-H31, HMS-301, FMS121, FMS123, FMS131, FMS141, FMS221 (named above) are not limited to these.

As the fluorine compound, a compound having a fluoroalkyl group is preferable. The fluoroalkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and a straight chain (for example, —CF ₂ CF ₃ , —CH ₂ (CF ₂ ) ₄ H, —CH ₂ (CF ₂ ) ₈ CF ₃ , —CH ₂ CH ₂ (CF ₂ ) ₄ H, etc.), even branched structures (eg, CH (CF ₃ ) ₂ , CH ₂ CF (CF ₃ ) ₂ , CH (CH ₃ ) CF ₂ CF ₃ , CH (CH ₃ ) (CF ₂ ) ₅ CF ₂ H, etc.), alicyclic structures (preferably 5-membered or 6-membered rings such as perfluorocyclohexyl group, perfluorocyclopentyl, etc. Group or an alkyl group substituted with these, and may have an ether bond (for example, CH ₂ OCH ₂ CF ₂ CF ₃ , CH ₂ CH ₂ OCH ₂ C ₄ F ₈ H, CH ₂ CH _{2 CH 2 CH 2 C 8 F 17} , CH 2 CH 2 OCF 2 CF 2 OCF 2 CF 2 H , etc.). A plurality of the fluoroalkyl groups may be contained in the same molecule.

  It is preferable that the fluorine-based compound further has a substituent that contributes to bond formation or compatibility with the low refractive index layer film. The substituents may be the same or different, and a plurality of substituents are preferable. Examples of preferred substituents include acryloyl group, methacryloyl group, vinyl group, aryl group, cinnamoyl group, epoxy group, oxetanyl group, hydroxyl group, polyoxyalkylene group, carboxyl group, amino group and the like. The fluorine-based compound may be a polymer or an oligomer with a compound not containing a fluorine atom, and the molecular weight is not particularly limited. Although there is no restriction | limiting in particular in fluorine atom content of a fluorine-type compound, It is preferable that it is 20 mass% or more, It is especially preferable that it is 30-70 mass%, It is most preferable that it is 40-70 mass%. Examples of preferred fluorine-based compounds include Daikin Chemical Industries, Ltd., R-2020, M-2020, R-3833, M-3833 (named above), Dainippon Ink Co., Ltd., Megafac F-171. , F-172, F-179A, and defender MCF-300 (named above), but are not limited thereto.

  For the purpose of imparting properties such as dust resistance and antistatic properties, a known cationic surfactant or a dustproof agent such as a polyoxyalkylene compound, an antistatic agent, or the like can be appropriately added. These dustproofing agent and antistatic agent may contain the structural unit as a part of the function in the above-mentioned silicone compound or fluorine compound. When these are added as additives, it is preferably added in the range of 0.01 to 20% by mass of the total solid content of the low refractive index layer, more preferably in the range of 0.05 to 10% by mass. Particularly preferred is 0.1 to 5% by mass. Examples of preferred compounds include, but are not limited to, Dainippon Ink Co., Ltd., MegaFace F-150 (trade name), Toray Dow Corning Co., Ltd., SH-3748 (trade name), and the like. Do not mean.

[Low refractive index particles]
The inorganic particles contained in the low refractive index layer desirably have a low refractive index, and examples thereof include fine particles of magnesium fluoride and silica. In particular, silica fine particles are preferable in terms of refractive index, dispersion stability, and cost.
The average particle diameter of the silica fine particles is preferably 10% to 150% of the thickness of the low refractive index layer, more preferably 15% to 80%, and still more preferably 40% to 60%. That is, when the thickness of the low refractive index layer is 100 nm, the particle size of the silica fine particles is preferably 10 nm or more and 150 nm or less, more preferably 15 nm or more and 80 nm or less, and further preferably 40 nm or more and 60 nm or less.
Here, the average particle diameter of the inorganic particles is measured by a Coulter counter.

  If the particle size of the silica fine particles is too small, the effect of improving the scratch resistance is reduced. If it is too large, fine irregularities are formed on the surface of the low refractive index layer, and the appearance such as black tightening and the integrated reflectance are deteriorated. The silica fine particles may be either crystalline or amorphous, and may be monodispersed particles or aggregated particles as long as a predetermined particle size is satisfied. The shape is most preferably a spherical diameter, but there is no problem even if the shape is indefinite.

Further, at least one kind of silica fine particles having an average particle size of less than 25% of the thickness of the low refractive index layer (referred to as “small size particle size silica particles”) is used as silica fine particles having the above particle size (“large size particles”). It is preferably used in combination with “silica fine particles having a diameter”.
Since the fine silica particles having a small particle size can exist in the gaps between the fine silica particles having a large particle size, they can contribute as a retaining agent for the fine silica particles having a large particle size.
When the low refractive index layer is 100 nm, the average particle size of the silica fine particles having a small size is preferably from 1 nm to 20 nm, more preferably from 5 nm to 15 nm, and particularly preferably from 10 nm to 15 nm. Use of such silica fine particles is preferable in terms of raw material costs and a retaining agent effect.

The coating amount of the low refractive index particles is ^{preferably 1mg / m 2 ~100mg / m 2} , more preferably ^{5mg / m 2 ~80mg / m 2} , more preferably from ^{10mg / m 2 ~60mg / m 2} . If the amount is too small, the effect of improving the scratch resistance is reduced. If the amount is too large, fine irregularities are formed on the surface of the low refractive index layer, and the appearance such as black tightening and the integrated reflectance are deteriorated.

[Hollow silica particles]
For the purpose of further reducing the refractive index, it is preferable to use hollow silica fine particles.

The hollow silica fine particles preferably have a refractive index of 1.15 to 1.40, more preferably 1.17 to 1.35, and most preferably 1.17 to 1.30. The refractive index here represents the refractive index of the entire particle, and does not represent the refractive index of only the outer shell silica forming the hollow silica particles. At this time, when the radius of the cavity in the particle is a and the radius of the particle outer shell is b, the porosity x expressed by the following formula (VIII) is (formula VIII)
^{x = (4πa 3/3)} / (4πb 3/3) × 100
Preferably it is 10-60%, More preferably, it is 20-60%, Most preferably, it is 30-60%. If the hollow silica particles are made to have a lower refractive index and a higher porosity, the thickness of the outer shell becomes thinner and the strength of the particles becomes weaker. From the viewpoint of scratch resistance, the low refractive index is less than 1.15. Rate particles are not preferred.

  A method for producing hollow silica is described in, for example, Japanese Patent Application Laid-Open Nos. 2001-233611 and 2002-79616. In particular, particles having cavities inside the shell and having fine pores in the shell are particularly preferred. The refractive index of these hollow silica particles can be calculated by the method described in JP-A-2002-79616.

The coating amount of the hollow silica is ^preferably from ^{1mg / m 2 ~100mg / m 2} , more preferably ^{5mg / m 2 ~80mg / m 2} , more preferably from ^{10mg / m 2 ~60mg / m 2} . If the amount is too small, the effect of lowering the refractive index and the effect of improving the scratch resistance will be reduced.
The average particle diameter of the hollow silica is preferably 30% to 150% of the thickness of the low refractive index layer, more preferably 35% to 80%, and still more preferably 40% to 60%. That is, if the thickness of the low refractive index layer is 100 nm, the particle size of the hollow silica is preferably 30 nm to 150 nm, more preferably 35 nm to 100 nm, and still more preferably 40 nm to 65 nm.
If the particle size of the silica particles is too small, the proportion of cavities will decrease and a decrease in refractive index cannot be expected. Getting worse. The silica fine particles may be either crystalline or amorphous, and monodisperse particles are preferred. The shape is most preferably a spherical diameter, but there is no problem even if the shape is indefinite.
Further, two or more kinds of hollow silica having different particle average particle sizes can be used in combination. Here, the average particle diameter of the hollow silica can be determined from an electron micrograph.
The specific surface area of the hollow silica in the present invention is preferably from 20 to 300 m ² / g, more preferably 30~120m ² / g, most preferably 40~90m ² / g. The surface area can be obtained by the BET method using nitrogen.

  In the present invention, silica particles having no voids can be used in combination with hollow silica. The preferred particle size of silica without voids is 30 nm to 150 nm, more preferably 35 nm to 100 nm, and most preferably 40 nm to 80 nm.

[Protective film for polarizing plate]
When the antireflection film of the present invention is used in a liquid crystal display device, a low refractive index layer is provided in order to use the antireflection film as a surface protective film for a polarizing film (protective film for a polarizing plate) in preparing a polarizing plate. It is essential to improve the adhesion to the polarizing film containing polyvinyl alcohol as a main component by hydrophilizing the surface of the transparent support opposite to the side, that is, the surface to be bonded to the polarizing film.

As the transparent support, it is particularly preferable to use a triacetyl cellulose film.
As a method for producing a protective film for polarizing plate in the present invention, (1) each of the above-mentioned layers (eg, hard coat layer, medium refractive index layer, two surface layers, etc.) on one surface of a previously saponified transparent support. There are two methods: (2) a method of coating each layer on one side of the transparent support, and then a saponification treatment on the side to be bonded to the polarizing film. Since the surface to which the coat is to be applied is hydrophilized, it is difficult to ensure the adhesion between the support and the hard coat layer, so the method (2) is preferred.

[Saponification]
(1) Immersion method This is a technique in which an antireflection film is immersed in an alkaline solution under appropriate conditions to saponify all surfaces that are reactive with alkali on the entire surface of the film, requiring no special equipment. Therefore, it is preferable from the viewpoint of cost. The alkaline liquid is preferably a sodium hydroxide aqueous solution. A preferred concentration is 0.5 to 3 mol / l, particularly preferably 1 to 2 mol / l. The liquid temperature of a preferable alkali liquid is 30-70 degreeC, Most preferably, it is 40-60 degreeC.
The combination of the above saponification conditions is preferably a combination of relatively mild conditions, but can be set according to the material and configuration of the antireflection film and the target contact angle.
After being immersed in the alkaline solution, it is preferable to sufficiently wash with water or neutralize the alkaline component by immersing in a dilute acid so that the alkaline component does not remain in the film.

By saponification treatment, the surface of the transparent support opposite to the surface having the antireflection layer is hydrophilized. The protective film for polarizing plate is used by adhering the hydrophilic surface of the transparent support to the polarizing film.
The hydrophilized surface is effective for improving the adhesiveness with the adhesive layer mainly composed of polyvinyl alcohol.
In the saponification treatment, the lower the contact angle with water on the surface of the transparent support opposite to the side having the low refractive index layer, the better from the viewpoint of adhesion to the polarizing film, while the dipping method simultaneously reduces the low refractive index. Since the surface having the rate layer is damaged by alkali, it is important to set the reaction conditions to the minimum necessary. As an index of the damage received by the antireflection layer due to alkali, particularly when the surface of the transparent support opposite to the side having the antireflection structure layer, that is, the bonding angle of the antireflection film, the contact angle with water is used. When the support is triacetylcellulose, the contact angle is preferably 20 to 50 degrees, preferably 30 to 50 degrees, more preferably 40 to 50 degrees. If it is 50 degrees or more, there is a problem in the adhesion to the polarizing film, which is not preferable. On the other hand, if the angle is less than 20 degrees, the damage received by the antireflection film is too large, and physical strength and light resistance are impaired.

(2) Alkaline liquid application method As a means for avoiding damage to the antireflection film in the above-described immersion method, the alkaline liquid is applied only on the surface opposite to the surface having the antireflection film under appropriate conditions, heated, washed with water, A drying alkaline solution coating method is preferably used. The application in this case means that an alkali solution or the like is brought into contact only with the surface to be saponified, and at this time, the contact angle with respect to water of the bonded surface of the antireflection film is 10 to 50 degrees. It is preferable to perform a saponification treatment. In addition to the application, it may include spraying, contact with a belt containing liquid, or the like. By adopting these methods, a separate facility and process for applying an alkaline solution are required, which is inferior to the immersion method (1) from the viewpoint of cost. On the other hand, since the alkali solution contacts only the surface to be saponified, the opposite surface can have a layer using a material that is weak against the alkali solution. For example, vapor deposition films and sol-gel films have various effects such as corrosion, dissolution, peeling, etc. caused by alkali solution, so it is not desirable to use the immersion method, but this coating method does not contact the solution and should be used without problems. Is possible.

  In any of the saponification methods (1) and (2) above, since each layer can be formed by unwinding from a roll-shaped support, a series of operations can be performed in addition to the above-described antireflection film production process. You can go. Furthermore, the polarizing plate can be produced more efficiently than the same operation with a single wafer by continuously performing the pasting step with the polarizing plate made of the unwound support.

[Image display device]
The optical film of the present invention and the polarizing plate comprising the optical film are a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), a cathode tube display (CRT), a field emission display (FED). ), And various image display devices such as a surface electric field display (SED). For example, the image display device preferably includes at least an image control unit and an image display unit (image display panel), and is disposed so that the low refractive index layer is on the viewing side. Further, when the optical film of the present invention is an antireflection film, a polarizing plate having the antireflection film can be used by directly adhering to a glass of a liquid crystal cell of a liquid crystal display device or via another layer.

  In order to describe the present invention in detail, examples will be described below, but the present invention is not limited thereto. Unless otherwise specified, “part” and “%” are based on mass.

(Synthesis of perfluoroolefin copolymer (P1))
In a 1-liter separable flask equipped with a magnetic stirrer, a glass cooling tube, and a thermometer, a hydroxyl group-containing fluorine-containing polymer (fluorinated silicone-containing thermosetting polymer described in Example 1 of JP-A-11-189621) 50.0 g of average molecular weight 35000), 0.01 g of 2,6-di-t-butylmethylphenol and 370 g of methyl ethyl ketone (MEK) as a polymerization inhibitor were charged and dissolved at 20 ° C. Next, 3.0 g of 2-methacryloyloxyethyl isocyanate was added to this system and stirred until the solution became homogeneous, then 0.1 g of dibutyltin dilaurate was added to start the reaction, and the temperature of the system was changed to 55. By maintaining the temperature at ˜65 ° C. and continuing stirring for 5 hours, a MEK solution of a perfluoroolefin copolymer (P1) in which about 30% of the hydroxyl groups were methacrylated was obtained.

(Preparation of sol solution a)
Add a stirrer, a reactor equipped with a reflux condenser, 120 parts by mass of methyl ethyl ketone, part by mass of acryloyloxypropyltrimethoxysilane (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.), 3 parts by mass of diisopropoxyaluminum ethyl acetoacetate After mixing, 30 parts by mass of ion-exchanged water was added and reacted at 60 ° C. for 4 hours, and then cooled to room temperature to obtain sol solution a. The mass average molecular weight was 1600, and among the components higher than the oligomer component, the component having a molecular weight of 1000 to 20000 was 100%. Further, from the gas chromatography analysis, the raw material acryloyloxypropyltrimethoxysilane did not remain at all.

(Preparation of dispersion A)
Hollow silica fine particle sol (Isopropyl alcohol silica sol, average particle diameter 60 nm, shell thickness 10 nm, silica concentration 20 mass%, silica particle refractive index 1.31, change size according to Preparation Example 4 of JP-A-2002-79616. Prepared) 30 parts by mass of acryloyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 1.5 parts by mass of diisopropoxyaluminum ethyl acetate were added to and mixed with 500 parts by mass. Part by weight was added. After making it react at 60 degreeC for 8 hours, it cooled to room temperature and added 1.8 mass parts of acetylacetone. While adding methyl isobutyl ketone so that the silica content was almost constant, the solvent was replaced by vacuum distillation at a pressure of 20 kPa. Finally, the solid content concentration was adjusted to 30% by mass with methyl isobutyl ketone to obtain dispersion A. There was no generation of foreign matter in the dispersion. When the residual amount of isopropyl alcohol in the obtained dispersion A was analyzed by gas chromatography, it was 1.5%.

[Example 1]
(Preparation of antireflection film)

(Adjustment of hard coat layer coating solution HC-A)
36 parts by mass of modified dipentaerythritol hexaacrylate (DPCA-120, manufactured by Nippon Kayaku Co., Ltd.) was dissolved in a mixed solvent of 7.0 parts by mass of methyl ethyl ketone and 30.5 parts by mass of methyl isobutyl ketone. After adding 1.5 parts by mass of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) to the resulting solution and stirring until dissolved, 25 parts by mass of MIBK-ST (average particle size of 10 to 20 nm, solid content) 30 mass% SiO ₂ sol methyl isobutyl ketone dispersion (manufactured by Nissan Chemical Co., Ltd.) was added and stirred to obtain a mixture, which was filtered through a polypropylene filter (PPE-03) having a pore size of 3 μm and hard-coated. A layer coating solution HC-A was prepared.

(Adjustment of coating liquid MA for medium refractive index layer)
Commercially available zirconia-containing UV curable hard coat solution (Desolite Z7404, manufactured by JSR Corporation), solid content concentration of about 61%, solvent methyl isobutyl ketone, ZrO ₂ content in solid content of about 70%, polymerizable monomer, polymerization initiator Contained) 49.2 parts by mass of 40 parts by mass of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, Nippon Kayaku Co., Ltd.) so that the solid content concentration is 3.5% by weight To the mixture, methyl isobutyl ketone (MiBK) and isopropanol (IPA) were added and stirred for 10 minutes. The ratio of MiBK to IPA was adjusted to 1: 1.5 (mass ratio). The mixed solution was filtered through a polypropylene filter (PPE-03) having a pore diameter of 3 μm to prepare a coating solution MA for a medium refractive index layer.
The refractive index of the layer formed from this coating solution was 1.60.

(Adjustment of coating liquid HA for high refractive index)
Commercially available zirconia-containing UV curable hard coat solution (Desolite Z7404, manufactured by JSR Corporation, solid content concentration of about 61%, solvent methyl isobutyl ketone, ZrO ₂ content of solid content of about 70%, polymerizable monomer, polymerization initiator included ) Were added with methyl isobutyl ketone (MiBK) and isopropanol (IPA) to a solid content concentration of 3.0% and stirred for 10 minutes. The ratio of MiBK to IPA was adjusted to 1: 2 (mass ratio).
The mixed solution was filtered through a polypropylene filter (PPE-03) having a pore diameter of 3 μm to prepare a coating solution HA for high refractive index.
The refractive index of the layer formed from this coating solution was 1.72.

(Adjustment of coating solution LA for low refractive index layer)
Thermally crosslinkable fluorine-containing polymer having a refractive index of 1.44 containing polysiloxane and hydroxyl group (JTA113, solid content concentration 6%, manufactured by JSR Corporation) 283 parts by mass, colloidal silica dispersion MEK-ST-L (trade name) , 30 parts by mass of an average particle diameter of 45 nm, solid content concentration of 30%, manufactured by Nissan Chemical Co., Ltd.) and 10 parts by mass of the sol solution a, and after substituting the solvent with IPA under reduced pressure distillation, It adjusted to 2.2 mass%. After stirring, the mixture was filtered through a polypropylene filter having a pore diameter of 1 μm to prepare a low refractive index layer coating solution LA. The refractive index of the layer formed with this coating solution was 1.45.

(Preparation of antireflection film by simultaneous layering)
The antireflection film of Example 1 was prepared by the following procedure. Using a composite coater consisting of one slot die layer and three slide layers on a triacetylcellulose film (TAC-TD80U, manufactured by Fuji Film Co., Ltd., refractive index: 1.48) having a thickness of 80 μm, the above hard coat layer Coating liquid HC-A, medium refractive index layer coating liquid MA, high refractive index coating liquid HA, and low refractive index coating liquid LA so that the film thickness after drying is 13 μm, 65 nm, 120 nm, and 90 nm, respectively. The wet coating amount was adjusted as appropriate, coating was performed while the web was conveyed at a speed of 30 m / min, and then dried at 100 ° C. for 2 minutes. Next, purging with nitrogen and irradiating with UV rays of 500 mJ / cm ² under the condition that the oxygen concentration is 0.05% by volume, the coating layer is cured, and further heat-cured at 110 ° C. for 10 minutes to produce an antireflection film. did. A metal halide lamp with a linear output of 160 W / cm was used for ultraviolet irradiation.

[Comparative Example 1]
The antireflection film of Comparative Example 1 (corresponding to a method of sequentially forming layers) was prepared by the following procedure. Apply the above hard coat layer coating solution HC-A to a 80 μm thick triacetylcellulose film (TAC-TD80U, manufactured by Fuji Film Co., Ltd., refractive index: 1.47) using a throttle die coater. And dried at 100 ° C. for 2 minutes. Next, purging with nitrogen and irradiating with ultraviolet rays of 70 mJ / cm ² under the condition that the oxygen concentration was 0.1% by volume, the coating layer was cured, and a hard coat layer (refractive index: 1.51, film thickness: 13 μm). ) Was formed.
Subsequently, the medium refractive index layer coating solution MA was applied using a throttle die coater, dried at 100 ° C., purged with nitrogen, and irradiated with ultraviolet rays at a concentration of 0.1% by volume of 200 mJ of ultraviolet rays. / Cm ^{2 was} applied to cure the coating layer, and a medium refractive index layer (film thickness: 65 nm) was provided.
Subsequently, the coating liquid HA for the high refractive index layer is applied using a throttle die coater, dried at 100 ° C., purged with nitrogen, and irradiated with 200 mJ of ultraviolet rays under a condition where the oxygen concentration is 0.1 vol%. / Cm ^{2 was} applied to cure the coating layer, and a high refractive index layer (film thickness: 120 nm) was provided.
Subsequently, the coating liquid LA for the low refractive index layer is applied using a throttle die coater, dried at 100 ° C., purged with nitrogen, and irradiated with ultraviolet rays of 500 mJ under a condition where the oxygen concentration is 0.05% by volume. / Cm ² irradiation and further heating at 110 ° C. for 10 minutes to cure the coating layer, and a low refractive index layer (refractive index: 1.45, film thickness: 90 nm) was provided.

[Comparative Example 2]
Medium refractive index layer coating liquid MB, in which IPA used as a solvent for the above medium refractive index layer coating liquid MA, high refractive index coating liquid HA, and low refractive index coating liquid LA is replaced with MEK, for high refractive index An antireflection film was prepared by simultaneous multilayering in the same manner as in Example 1 except that the coating liquid MB and the low refractive index coating liquid LB were used.

[Examples 2-5, Comparative Examples 3-4]
Using the solute composition of the coating liquid HC-A for hard coat layer and the coating liquid LA for low refractive index layer, using each coating liquid prepared with the main solvent in the solvent type and solution concentration as shown in Table 2, Using a hard coat layer coating liquid HC-A and a low refractive index coating liquid LA using a composite coater with one slot die layer and one slide layer, the film thickness after drying is 13 μm and 90 nm, respectively. The coating amount was adjusted as appropriate, coating was performed while the web was conveyed at a speed of 30 m / min, and then dried at 100 ° C. for 2 minutes. Next, purging with nitrogen and irradiating with UV rays of 500 mJ / cm ² under the condition that the oxygen concentration is 0.05% by volume, the coating layer is cured, and further heat-cured at 110 ° C. for 10 minutes to produce a low reflection film. did.

(Adjustment of hard coat layer coating solution HC-C)
42 parts by mass of modified dipentaerythritol hexaacrylate (DPCA-120, manufactured by Nippon Kayaku Co., Ltd.) was dissolved in a mixed solvent of 7.0 parts by mass of MEK and 42 parts by mass of MiBK. To the obtained solution, 1.5 parts by mass of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and 1.5 parts by mass (Irgacure 184, manufactured by Ciba Geigy) were added, stirred until dissolved, and a pore size of 3 μm. A hard coat layer coating solution HC-C was prepared by filtration through a polypropylene filter (PPE-03).

(Adjustment of coating liquid LC for low refractive index layer)
108 parts by mass of perfluoroolefin polymer (P1) 62 parts by mass (solid content), colloidal silica dispersion MEK-ST-L (trade name, average particle size 45 nm, solids concentration 30%, manufactured by Nissan Chemical Co., Ltd.) And 14.5 parts by mass of the sol liquid a were mixed, and the solid content concentration was adjusted to 2.2% by mass with MEK. After stirring and dissolving, the solution was filtered through a polypropylene filter having a pore diameter of 1 μm to prepare a low refractive index layer coating liquid LC. The refractive index of the layer formed with this coating solution was 1.43.

(Adjustment of coating liquid LD for low refractive index layer)
66 parts by mass (solid content) of perfluoroolefin polymer (P1), 96 parts by mass of hollow silica fine particle sol dispersion (dispersion A), and 14.5 parts by mass of the sol liquid a were dissolved in mixed MEK. It adjusted to 2.2 mass%. After stirring, the mixture was filtered through a polypropylene filter having a pore size of 1 μm to prepare a low refractive index layer coating solution LD. The refractive index of the layer formed by this coating solution was 1.39.

(Adjustment of coating liquid LE for low refractive index layer)
13.6 parts by mass of thermally crosslinkable fluorine-containing polymer (fluorinated silicone-containing thermosetting polymer described in Example 1 of JP-A-11-189621, number average molecular weight 35000), curing agent (Cymel 303; trade name, Nippon Cytec Industries, Ltd.) Co., Ltd.) 3.40 parts by mass, curing catalyst (Catalyst 4050; trade name, manufactured by Nippon Cytec Industries, Inc.) 0.33 parts by mass in IPA 400 parts by mass, and colloidal silica dispersion MEK- 30 parts by mass of ST-L (trade name, average particle size 45 nm, solid content concentration 30%, manufactured by Nissan Chemical Co., Ltd.) and 10 parts by mass of the sol solution a were mixed, and the solvent was replaced with IPA under reduced pressure distillation. After that, the solid content concentration was adjusted to 2.2% by mass. After stirring, the mixture was filtered through a polypropylene filter having a pore size of 1 μm to prepare a low refractive index layer coating solution LE. The refractive index of the layer formed by this coating solution was 1.44.

(Adjustment of coating solution LF for low refractive index layer)
10 parts by mass (solid content) of the perfluoroolefin copolymer (P1) was diluted with MEK and adjusted to 2.2% by mass. After stirring and dissolving, the mixture was filtered through a polypropylene filter having a pore size of 1 μm to prepare a low refractive index layer coating solution LF. The refractive index of the layer formed with this coating solution was 1.43.

[Example 6]
Adjust the wet coating amount appropriately so that the film thickness after drying the coating liquid HC-C for hard coat layer and the coating liquid LC for low refractive index is 11 μm and 90 nm, respectively, and the web is applied at a speed of 30 m / min. Application was carried out while transporting, followed by drying at 100 ° C. for 2 minutes. Next, purging with nitrogen and irradiating with ultraviolet rays of 500 mJ / cm ² under a condition where the oxygen concentration was 0.05% by volume, the coating layer was cured to prepare a low reflection film.

[Example 7]
A low antireflective film was prepared in the same manner as in Example 6 except that the low refractive index coating liquid LC was changed to the low refractive index coating liquid LD.

[Example 8]
Hard coat layer coating except that in the preparation of the hard coat layer coating solution HC-C, 4.23 parts by mass of translucent PMMA particles (MX-600, manufactured by Soken Chemical Co., Ltd.) having a particle size of 6 μm were added. The coating liquid HC-D for hard coat was prepared in the same manner as the liquid HC-C. The translucent particles were added with a 45% by mass MiBK dispersion, and the solid content concentration excluding the translucent particles in the hard coat layer coating solution was adjusted to 45% by mass.
In Example 6, an anti-glare low-reflection film was prepared in the same manner as in Example 6 except that the hard coat coating solution HC-D was used instead of the hard coat layer coating solution HC-C.

(Evaluation of antireflection film)
About the obtained film, the following items were evaluated. The results are summarized in Table 2.
(1) Reflectance The surface of the back of the film was roughened with sandpaper, then colored with black ink, and with no back reflection, 5 ° with a spectrophotometer V-550 (manufactured by JASCO Corporation). Specular reflectance and integral reflectance were measured.
(2) Coating surface shape The surface of the film cut out to a length of 30 cm in the coating direction was roughened with sandpaper, then colored with black ink, and the surface was observed visually with no back reflection. went. The superiority or inferiority of the scattering of white turbidity due to interference color and reflectance unevenness or layer mixing was evaluated according to the following indicators.
(Double-circle): It is optically uniform over the whole surface, and it looks as transparent black in directions other than regular reflection.
○: The transparency is poor, and it appears slightly cloudy.
Δ: Reflected light appears cloudy at first glance. It looks uneven in some places.
X: Appears to be clouded clearly and appears to be strongly uneven even in the surface.

  In Example 1, the integrated reflectance was 1.4%, which showed good antireflection performance. In Example 1, the solute main component (DPCA-120) of the hard coat layer of the first layer is insoluble in the main component (IPA) of the solvent of the second layer, that is, the condition of claim 1 is satisfied. ing. Comparative Example 1 can be said to have good performance with an integrated reflectance of 1.5%. However, since each layer is applied individually, the surface is partially different in color due to uneven application of each layer. It was. In Comparative Example 2, white turbidity and strong color unevenness occurred on the entire surface, resulting in a surface shape that was difficult to be called an optical film, and reflectance measurement was impossible. In Comparative Example 2, the main component of the solute of each layer is soluble in the solvent of the adjacent layer, and it is considered that the interlayer mixing was vigorously caused.

  Table 2 shows the results of the two-layer low reflection films of Examples 2 to 7 and Comparative Examples 3 to 4. In the films of Examples 2 and 3, the monomer material which is the lower layer solute is hardly soluble in IPA which is the upper layer solvent, and the fluoropolymer which is the upper layer solute is easily soluble in the lower layer solvent MiBK, that is, The relationship of claims 1 and 2 was satisfied, and interfacial mixing did not occur, and good reflectance performance was obtained. In Comparative Example 3, since the solute of the upper layer was insoluble in the solvent of the lower layer, the upper layer was not a uniform layer, and sea-island-like thickness unevenness occurred, resulting in a slightly whitish surface.

  In Examples 2 and 4, when the upper layer and lower layer coating liquids were mixed at a coating amount ratio (volume ratio), the phases were separated (that is, the relationship of claim 3 was satisfied). In Nos. 6 and 7, when the upper layer and lower layer coating liquids were mixed at a coating amount ratio (volume ratio) and the solvent was evaporated to dryness, phase separation occurred rapidly (that is, the relationship of claim 4 was satisfied). In these examples, interfacial mixing was suppressed immediately after coating, and as a result, a film with good reflectance performance was obtained. On the other hand, the film obtained in Comparative Example 4 had a white turbid surface, and the reflectance performance was not lowered. Moreover, since the optical film of this invention has a hard-coat layer, it is excellent also in abrasion resistance.

  In Example 8, the solubility of the upper layer and lower layer solutes and the properties of the mixed solution were the same as in Example 6. When the same evaluation was performed on the anti-glare low-reflection film of Example 8, the specular reflectance was 0.9% and the integrated reflectance was 1.4%, and good reflectance performance was obtained. In addition, the antiglare effect due to the surface unevenness made it difficult to recognize light sources such as fluorescent lamps and surrounding migration, and satisfactory performance as a surface film for display was obtained.

  In addition, the optical film of the present invention is a polarizing plate used for liquid crystal display devices of various modes, a surface protection plate combining a polarizing plate used for organic EL and a λ / 4 plate, a surface protection for flat CRT or PDP applied to a PET film. It could be used for various displays such as plates and SED surface protection films.

[Example 9]
Using the solute composition of the hard coat layer coating solution HC-A and the low refractive index layer coating solution LE, using each coating solution prepared with the main solvent in the solvent type and solution concentration as shown in Table 3, Using a composite coater with one slot die layer and one slide layer, the wet coating amount is appropriately adjusted so that the film thickness after drying the coating solution for hard coat layer and the coating solution for low refractive index is 13 μm and 90 nm, respectively. It adjusted and it apply | coated, conveying a web at the speed of 30 m / min. After drying at 80 ° C. for 2 minutes, it was further dried at 100 ° C. for 2 minutes. Next, purging with nitrogen and irradiating with UV rays of 500 mJ / cm ² under the condition that the oxygen concentration is 0.05% by volume, the coating layer is cured, and further heat-cured at 110 ° C. for 10 minutes to produce a low reflection film. did.

[Example 10]
Using the solute composition of the coating liquid HC-A for hard coat layer and the coating liquid LF for low refractive index layer, using each coating liquid prepared with the main solvent in the solvent type and solution concentration as shown in Table 3, Using a composite coater with one slot die layer and one slide layer, the wet coating amount is appropriately adjusted so that the film thickness after drying the coating solution for hard coat layer and the coating solution for low refractive index is 13 μm and 90 nm, respectively. It adjusted and it apply | coated, conveying a web at the speed of 30 m / min. After drying at 80 ° C. for 2 minutes, it was further dried at 100 ° C. for 2 minutes. Next, the film was purged with nitrogen and irradiated with ultraviolet rays of 500 mJ / cm ² under the condition that the oxygen concentration was 0.05% by volume to cure the coating layer, thereby preparing a low reflection film.

  The results evaluated in the same manner as in the above examples are shown in Table 3.

  According to Table 3, according to this invention, it turns out that the low reflection film excellent in planar shape is obtained simultaneously.

It is sectional drawing of the composite coater of the slot die and slide 1 layer which implemented this invention. (A) shows the cross-sectional shape of the slot die 13 of the present invention, and (B) shows the cross-sectional shape of a general slot die 30. It is sectional drawing which shows typically one Embodiment of the antireflection film of this invention. It is sectional drawing which shows typically another one Embodiment of the antireflection optical film of this invention. It is sectional drawing which shows typically another one Embodiment of the antireflection optical film of this invention.

Explanation of symbols

10 Coater 11 Backup roll W Web 13 Slot die 14, 54 Coating liquid 14a Bead 14b Coating film 15, 50 Pocket 16, 52 Slot 16a, 52a Slot opening 17 Tip lip 18 Land 18a Upstream lip land 18b Downstream lip land IUP Land length ILO of upstream lip land 18a Land length LO of downstream lip land 18b LO Overbite length (difference in distance between downstream lip land 18b and web W of upstream lip land 18a)
GL Gap between the tip lip 17 and the web W (gap between the downstream lip land 18b and the web W) 30 General slot die 31a Upstream lip land 31b Downstream lip land 32 Pocket 33 Slot 51 Slide 55 Cover

Claims (14)

Using at least two types of coating solutions containing a solvent and a solute on a transparent support, a step of simultaneously coating and forming at least two coating layers, and drying the solvent in the at least two coating layers A process,
When the at least two coating layers are 1, 2,..., N−1, n layers in order from the outermost surface toward the transparent support, the main component of the solute in the nth layer is n−1. A method for producing an optical film which is insoluble or hardly soluble in a main component of a solvent in a layer. Using at least two types of coating solutions containing a solvent and a solute on a transparent support, a step of simultaneously coating and forming at least two coating layers, and drying the solvent in the at least two coating layers A process,
When the at least two coating layers are 1, 2, ..., n-1, n layers in order from the outermost surface toward the transparent support, the main component of the solute in the n-1 layer is the first. The method for producing an optical film according to claim 1, wherein the optical film is easily soluble in a main component of the solvent in the n layer. Using at least two types of coating solutions containing a solvent and a solute on a transparent support, a step of simultaneously coating and forming at least two coating layers, and drying the solvent in the at least two coating layers A process,
The method for producing an optical film, which is a coating liquid that causes liquid-liquid phase separation and separates into two layers when the coating liquid of at least two layers is mixed at the same volume ratio as the coating amount. Using at least two types of coating solutions containing a solvent and a solute on a transparent support, a step of simultaneously coating and forming at least two coating layers, and drying the solvent in the at least two coating layers A process,
The coating solution of at least two layers is mixed as a one-phase solution when mixed at the same volume ratio as the coating amount, and the solvent amount is reduced by 10% by weight by drying the solvent in the mixed solution. -The manufacturing method of the optical film which is a coating liquid which raise | generates liquid phase separation and isolate | separates into two layers.   The manufacturing method of the optical film in any one of Claims 1-4 in which the coating liquid applied to the outermost layer of the said optical film contains a thermosetting type or an ionizing radiation hardening type fluorine-containing compound.   The method for producing an optical film according to claim 5, wherein the coating solution applied to the outermost layer further contains a silicone compound.   The manufacturing method of the optical film of Claim 5 or 6 in which the said fluorine-containing compound has a silicone structural unit in a molecule | numerator.   The at least 1 layer coating liquid applied to any layer other than the outermost layer of the said optical film contains the bifunctional or more polymerizable monomer and / or oligomer of Claim 1-7. Manufacturing method of optical film.   The at least 1 layer coating liquid applied to any layer other than the outermost layer of the said optical film contains translucent particle | grains with an average particle diameter of 1.0 micrometer or more. Manufacturing method of optical film.   The coating liquid of at least one layer applied to any layer other than the outermost layer of the optical film contains inorganic oxide fine particles having an average particle diameter of 100 nm or less and a refractive index of 1.9 or more. The manufacturing method of the optical film in any one of -9. The step of simultaneously coating and forming the at least two coating layers is a step of simultaneously coating and forming at least two coating layers with a composite coater having a slot die and a slide type coating head;
While supporting a web including a transparent support with a backup roller and continuously running, a lower layer is applied on the web using a slot die, and a slide type coating head disposed near the tip of the slot die is provided. The method for producing an optical film according to claim 1, wherein at least one upper layer is applied on the lower layer.   The manufacturing method of the optical film in any one of Claims 1-11 which has the process of hardening a coating film by heat processing and / or ionizing ray irradiation after the process of drying the solvent of the said at least 2 layer of coating layer.   The optical film manufactured with the manufacturing method of the optical film in any one of Claims 1-12.   An image display device comprising the optical film according to claim 13.

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