JP2022152936A - Optical film and manufacturing method therefor, and polarizing plate and display device equipped therewith - Google Patents

Abstract

To provide an optical film with which interlayer adhesion and light fastness are improved, a manufacturing method for the same, and a polarizing plate and a display device equipped with the same.SOLUTION: This optical film is composed of a base film, a highly adhesive layer and a barcode layer in the order stated. The highly adhesive layer contains an aqueous polyolefin resin, and each of the highly adhesive layer and the barcode layer contains a surface additive. The surface additive that the highly adhesive layer contains is a polyether modified silicone, the HLB value of the polyether modified silicone being in the range of 5 to 15, and the weight average molecular weight of the surface additive that the barcode layer contains is 4000 or less.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an optical film, a method for producing the same, and a polarizing plate and a display device having the same. More particularly, it relates to an optical film or the like with improved adhesion between layers and improved light resistance.

2. Description of the Related Art Technological development of liquid crystal display devices and organic EL display devices has progressed, and in recent years, display devices with excellent design, such as thin and flexibly bendable flexible displays, have been developed. Specifically, installation in such a manner as to be wrapped around a pillar in public facilities and installation as an alternative display device for measuring instruments such as a tachometer mounted in a vehicle are being considered.

The optical film contained in the polarizing plate provided in such a display device is a highly flexible thin film, and furthermore, in consideration of the usage environment of the display device, it is a film with excellent heat resistance and moisture resistance. Expected to be used.

On the other hand, many recent display devices have a function as a touch panel in which the display is directly touched with a finger or a pen, and high scratch resistance is required. In addition, a display device mounted in a vehicle is required to have high impact resistance from the viewpoint of safety to the human body.

These functions can be imparted by forming a hard coat layer on the optical film. However, since a cycloolefin film, for example, has few chemical reaction sites, the bond with the hard coat layer is weak. Therefore, there is a known technique for providing an easy-adhesion layer having a sufficient thickness between the optical film and the hard coat layer, but from the viewpoint of production, it has been desired to make the easy-adhesion layer thinner. .

Patent Literature 1 discloses a technique of an optical film having sufficient adhesiveness while having a relatively thin easy-adhesion layer. The easy-adhesion layer is characterized by containing a mixture of a polyolefin resin and a cellulose resin, but it is difficult to mix the resins uniformly and storage is difficult. In addition, the optical film was not sufficient in adhesion under an environment where it was exposed to light, that is, in light resistance.

Patent Document 2 discloses a technique for a silicone resin composition characterized by containing a hydroxy group-containing polysiloxane, an epoxy group-containing silane coupling agent, and an amino group-containing silicon compound. of silicone oil can be used as a diluent. However, the diluent is added for the purpose of adjusting the viscosity and flexibility of the resin composition, and the improvement of light resistance by adding the polyether-modified silicone oil has not been studied. rice field.

Japanese Patent No. 6453689 Japanese Patent No. 5175818

The present invention has been made in view of the above problems and situations, and the problems to be solved are an optical film with improved interlayer adhesion and light resistance, a method for producing the same, a polarizing plate having the same, and a It is to provide a display device.

In order to solve the above problems, in the process of studying the causes of the above problems, the inventors found that the adhesion between layers can be improved by selecting the resin used for the easy adhesion layer and the surface conditioner used for the easy adhesion layer and the hard coat layer. The inventors have also found that an optical film with improved light resistance, a method for producing the same, and a polarizing plate and a display device having the same can be provided, resulting in the present invention.
That is, the above problems related to the present invention are solved by the following means.

1. An optical film comprising a substrate film, an easy-adhesion layer, and a hard coat layer in this order, wherein the easy-adhesion layer contains a water-based polyolefin resin, and the easy-adhesion layer and the hard coat layer are each subjected to surface conditioning. agent, the surface conditioner contained in the easy adhesion layer is a polyether-modified silicone, the HLB value of the polyether-modified silicone is in the range of 5 to 15, and the hard coat layer contains The optical film, wherein the weight-average molecular weight of the surface conditioner is 4,000 or less.

2. 2. The optical film of item 1, wherein the base film contains a cycloolefin resin.

3. 3. The optical film according to item 1 or item 2, wherein the surface conditioner contained in each of the easy-adhesion layer and the hard coat layer is the same compound.

4. When the mass of the surface conditioner contained in the easy-adhesion layer and the hard coat layer is Mp and Mh, respectively, the content mass ratio (Mh/Mp) is in the range of 0.02 to 40. The optical film according to any one of items 1 to 3, characterized by:

5. An optical film manufacturing method for manufacturing the optical film according to any one of items 1 to 4, comprising a step of forming the easy-adhesion layer on the base film, and the easy-adhesion layer. A method for producing an optical film, comprising the step of forming the hard coat layer thereon.

6. A polarizing plate comprising the optical film according to any one of items 1 to 4.

7. 7. A display device comprising the polarizing plate according to claim 6.

By the means of the present invention, it is possible to provide an optical film with improved interlayer adhesion and light resistance, a method for producing the same, and a polarizing plate and a display device having the same.

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

A method of forming a hard coat layer is known for imparting scratch resistance and impact resistance to a substrate film. had a problem. Therefore, by forming the hard coat layer after forming the easily adhesive layer on the base film, the adhesion between the base film and the hard coat layer was improved.
However, considering the use of the film thus obtained in a display device, the adhesion between the layers in an environment where it is exposed to light, that is, the light resistance, is necessary. Adhesion was not sufficient.

The mechanism of adhesion between the easy-adhesion layer and the hard coat layer includes chemical interaction due to bonding caused by a chemical reaction (also referred to as "chemical adsorption"), and physical interaction due to intermolecular force ("physical adsorption"). ”) can be considered. Specifically, the functional groups of the resin contained in the easy-adhesion layer and the resin contained in the hard coat layer are bonded to each other and attracted to each other by intermolecular force. Under an environment exposed to light, it is believed that this chemical bond is broken and compounds such as resins are oxidatively deteriorated, weakening the chemical interaction and lowering the adhesive force.

Therefore, the inventor thought that high adhesion could be maintained if the physical interaction functioned sufficiently even if the chemical interaction decreased. Specifically, in order to strengthen the intermolecular force between the easy-adhesion layer and the hard coat layer, the distance between the easy-adhesion layer and the hard coat layer should be made sufficiently close. We have found that an optical film with improved interlayer adhesion and light resistance can be obtained by adding a high-molecular-weight surface modifier to the easy-adhesion layer and further adding a low-molecular-weight surface modifier to the hard coat layer. .

Although the details of the mechanism of expression of this function have not yet been clarified, the following possibilities are presumed.

The easy-adhesion layer is preferably formed by direct coating on the substrate film from the viewpoint of molding processability. However, when the polyolefin resin used for the easy-adhesion layer is dissolved in an organic solvent and applied, cracks occur in the substrate film. occur. Therefore, by using a water-based polyolefin resin that is an aqueous dispersion, an easy-adhesion layer can be formed on the substrate film by coating. However, the surface tension of water is relatively high, and if it is applied directly to the base film, repelling and poor wetting will occur, making it difficult to form a layer of uniform thickness.

The surface conditioner added to the easy-adhesion layer according to the present invention is polyether-modified silicone, and by changing the structure of the side chain, it is possible to change the balance between hydrophilic groups and hydrophobic groups in the molecule, The polarity of the compounds can be controlled. The HLB value is a numerical value that represents the balance between hydrophilic groups and hydrophobic groups in a molecule. easily adsorbed on the surface of the liquid (liquid-gas interface). Also, by setting the HLB value within the above range, the compatibility with the resin used for forming the hard coat layer can be enhanced.

Therefore, even in the easy-adhesion layer according to the present invention containing a water-based polyolefin resin, the polyether-modified silicone is easily adsorbed and oriented on the surface of the easy-adhesion layer, and continues to be adsorbed and oriented even when the resin concentration increases during the drying process. be able to. The polyether-modified silicone, which has a relatively low surface tension, uniformly adsorbs to the surface of the easy-adhesion layer, thereby forming a layer with a uniform thickness and smoothing the surface. Furthermore, the polyether-modified silicone is highly compatible with and mixes with the resin used for the hard coat layer, particularly the acrylate resin, so that the distance between the easy-adhesion layer and the hard coat layer can be made sufficiently close.

By adding a surface modifier to the hard coat layer, a layer having a uniform thickness can be formed and the surface can be made smoother. Moreover, from the viewpoint of moldability, it is preferably formed by direct coating on the easy-adhesion layer.

However, in the process of applying and drying the composition for forming a hard coat layer on the easy adhesion layer, the polyether-modified silicone tries to be adsorbed and oriented on the surface of the hard coat layer, which is the interface between the liquid and the gas, and the surface of the easy adhesion layer will move from Therefore, by setting the weight-average molecular weight of the surface modifier contained in the hard coat layer to 4000 or less, that is, by making the surface modifier with a relatively fast adsorption speed, the polyether-modified silicone can be used as an easy-adhesion layer. It can stay on the surface and maintain high adhesion between the easy-adhesion layer and the hard coat layer.

Basic layer structure of the optical film of the present invention Basic layer structure of the polarizing plate of the present invention

An optical film of the present invention is an optical film comprising a substrate film, an easy-adhesion layer and a hard coat layer in this order, wherein the easy-adhesion layer contains a water-based polyolefin resin, and the easy-adhesion layer and the hard coat are Each layer contains a surface modifier, the surface modifier contained in the easy-adhesion layer is a polyether-modified silicone, and the polyether-modified silicone has an HLB value in the range of 5 to 15. and the surface modifier contained in the hard coat layer has a weight-average molecular weight of 4,000 or less.
This feature is a technical feature common to or corresponding to the following embodiments.

As an embodiment of the present invention, it is more preferable that the base film contains a cycloolefin resin from the viewpoint of resistance to moisture and heat.

From the viewpoint of adhesion, it is more preferable that the surface conditioner contained in each of the easy-adhesion layer and the hard coat layer is the same compound.

From the viewpoint of appearance, when the mass of the surface conditioner contained in the easy-adhesion layer and the hard coat layer is Mp and Mh, respectively, the content mass ratio (Mh/Mp) is 0.02 to 40. is more preferably within the range of

The method for producing an optical film of the present invention comprises a step of forming the easy-adhesion layer on the base film and a step of forming the hard coat layer on the easy-adhesion layer, from the viewpoint that the layer can be formed by direct coating. It is more preferred to include

The optical film of the present invention can be suitably used for a polarizing plate and a display device equipped with the polarizing plate.

DETAILED DESCRIPTION OF THE INVENTION The present invention, its constituent elements, and embodiments and modes for carrying out the present invention will be described in detail below. In the present application, "-" is used to mean that the numerical values before and after it are included as the lower limit and the upper limit.

<<1 Outline of the optical film of the present invention>>
An optical film of the present invention is an optical film comprising a substrate film, an easy-adhesion layer and a hard coat layer in this order, wherein the easy-adhesion layer contains a water-based polyolefin resin, and the easy-adhesion layer and the hard coat are Each layer contains a surface modifier, the surface modifier contained in the easy-adhesion layer is a polyether-modified silicone, and the polyether-modified silicone has an HLB value in the range of 5 to 15. and the surface modifier contained in the hard coat layer has a weight-average molecular weight of 4,000 or less.

FIG. 1 shows an example of the basic configuration of the layer configuration of the optical film 10 of the present invention. The optical film 10 of the present invention has an easily adhesive layer 2 between the hard coat layer 1 and the base film 3 .

The configuration of the optical film of the present invention will be described in detail below.

<1.1 Easy Adhesion Layer>
The easy-adhesion layer according to the present invention contains a water-based polyolefin resin, further contains a surface conditioner, the surface conditioner is a polyether-modified silicone, and the polyether-modified silicone has an HLB value of 5 to 15. is within the range of

In the present invention, the term "facilitated adhesion layer" refers to a layer that does not contribute to adhesion as a whole layer, but to which adhesive strength can be imparted by appropriately performing any additive and treatment. In this specification, the "adhesion" between the easy-adhesion layer and the hard coat layer is also referred to as "adhesion" because it is presumed that the distance between the layers is sufficiently close and the intermolecular force is large.

The thickness of the easy-adhesion layer according to the present invention is preferably in the range of 0.3 to 1 μm from the viewpoint of stability of initial adhesion.

<1.1.1 Aqueous polyolefin resin>
The resin used for the easy-adhesion layer according to the present invention is characterized by being a water-based polyolefin resin.
"Aqueous polyolefin resin" refers to a modified polyolefin resin having an anionic or cationic polar group that makes it dispersible in an aqueous medium.
Generally, polyolefin resins are non-polar and hydrophobic, so they have low wettability (hydrophilicity) and are difficult to apply or adhere to. Makes molding easier.

As a method for improving the moldability of a polyolefin resin, there is a method of dissolving the polyolefin resin in an organic solvent. As shown in the manufacturing method described later, it is preferable to form the easy-adhesion layer directly on the base film. In this method, cracks are likely to occur in the base film.
However, by using a water-based polyolefin resin, the easy-adhesion layer according to the present invention is easy to mold and can be formed directly on the base material without causing cracks.

In addition, since the water-based polyolefin resin has relatively few polar groups and is highly hydrophobic, even if the resin concentration becomes high during the drying process during the formation of the easy-adhesion layer, the polyether-modified silicone, which will be described later, does not easily adsorb to the resin. It is thought that the adsorption orientation on the surface of the adhesive layer can be continued.

Examples of water-based polyolefin resins include ethylene-propylene copolymers having polar groups, ethylene-vinyl acetate copolymers, polyethylene-based ionomers, ethylene-vinyl alcohol copolymers, ethylene-acrylic acid copolymers, ethylene-vinyl chloride copolymers. It can employ coalescence, etc., and can exist in the form of an aqueous solution, an aqueous dispersion, or an aqueous emulsion.
Among them, ethylene-unsaturated carboxylic acid copolymers, ethylene-based ionomer resins intermolecularly bonded with metal ions such as sodium and zinc, ethylene-acrylic acid copolymers, and ethylene-vinyl acetate copolymers are preferred.

In particular, the aqueous polyolefin resin according to the present invention preferably contains an olefin component and an unsaturated carboxylic acid component as copolymer components, and the olefin component contains propylene and an olefin other than propylene. More preferably, the olefin other than propylene contains butene and does not contain ethylene. It is known that the mass ratio of propylene/olefin other than propylene is preferably 60/40 to 80/20 from the viewpoint of adhesion and the like.

The form of copolymerization of each component of the aqueous polyolefin resin is not particularly limited, and any known polymerization method such as random copolymerization, block copolymerization, or graft copolymerization can be employed. Copolymerization or graft copolymerization is preferred.

The unsaturated carboxylic acid component is not particularly limited, but acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, aconitic acid, aconitic anhydride, fumaric acid, crotonic acid, citracone Acid, mesaconic acid, allylsuccinic acid and the like can be exemplified. Among them, maleic anhydride is more preferable.

As the aqueous medium for dispersing the polyolefin resin, in addition to using water alone, for example, a combination of known organic solvents such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, methyl ethyl ketone, and dimethylformamide and water. It is also possible to use

In addition, a basic compound may be added to facilitate dispersion of the polyolefin resin, and although the basic compound is not particularly limited, ammonia or an organic amine compound is preferred. Specific examples of organic amine compounds include, but are not limited to, ethylamine, propylamine, isopropylamine, 3-methoxypropylamine, diethylamine, and dipropylamine. The amount of the basic compound to be blended is preferably 0.5 to 10 equivalents with respect to the carboxy groups in the polyolefin resin.

Specific examples of water-based polyolefin resins used include those manufactured by Unitika Ltd. under the trade names of "Arrowbase (registered trademark) series" SE-1010, SE-1013N, SE-1030N, SD-1010, TC-4010, TD-4010, Manufactured by Toho Chemical Co., Ltd., trade name "Hitec series" S3148, S3121, S8512, P-5060N, P-9018, Mitsui Chemicals, trade name "Unistor (registered trademark) series" S-120, S-75N, V100 , H-200, H-300, EV210H, manufactured by Mitsui Chemicals, trade name "Chemipearl (registered trademark) series" XHP-400, manufactured by Sumitomo Seika Co., Ltd., trade name "Saixen (registered trademark) series" Zaixen A, Zaixen NZ-1004, NZ-1005, NZ-1022, etc., manufactured by Toyobo Co., Ltd. under the trade name of "Hardren (registered trademark) series".

<1.1.2 Surface conditioner for easy adhesion layer>
The surface conditioner contained in the easy-adhesion layer according to the present invention (also referred to as "easy-adhesion layer surface conditioner") is a polyether-modified silicone, and the polyether-modified silicone has an HLB value of 5 to 15. It is characterized by being within the range.

In order to improve the adhesion between the easy-adhesion layer and the hard coat layer, that is, to strengthen the intermolecular force between the easy-adhesion layer and the hard coat layer, it is necessary to make the distance between the easy-adhesion layer and the hard coat layer sufficiently close. . That is, the adhesiveness can be improved by incorporating a surface conditioner that is highly compatible with the resin used for forming the hard coat layer into the easy-adhesion layer.

A "surface conditioner" is added for the purpose of preventing defects occurring on the surface of a coating film during and after coating. The "surface conditioner for an easy-adhesion layer" according to the present invention refers to an agent added for the purpose of imparting good wettability and uniformity to the coating film and smoothness and slipperiness of the coating film surface. In order to obtain such effects, the surface tension of the coating liquid must be lower than the surface tension of the object to be coated.

Therefore, as the surface conditioner for the easy adhesion layer according to the present invention, a compound having both a hydrophilic group and a hydrophobic group in the molecule is preferable. Such compounds exist on the surface of the coating film, greatly change the surface energy thereof, and bring about great changes in the physical properties of the surface of the coating film.

[Polyether-modified silicone]
The surface conditioner for an easy-adhesion layer according to the present invention is characterized by being polyether-modified silicone.
Here, "polyether-modified silicone" refers to a compound in which a polyoxyalkylene group is introduced into a part of the siloxane bonds of a polysiloxane compound.

A silicone compound is a compound having a siloxane bond (Si--O--Si) in its main skeleton, is highly flexible, has a helical structure in its entirety, and its side chains are easily oriented on the surface of the helical structure. By having an alkyl group such as a methyl group in the side chain, the intermolecular force can be reduced and the surface tension can be reduced. In addition, the main chain (main skeleton) is non-polar, and by adding a polar substituent to the side chain, it is possible to form a surfactant structure having a polar part and a non-polar part in the same molecule. In particular, by having a polyoxyalkylene group in the side chain, the silicone compound exhibits surface activity and is adsorbed and oriented on the surface of the easy-adhesion layer.

In addition, the silicone compound does not show polarity as a whole molecule, but a part of the molecule exhibits polarity. It is thought that even if the concentration increases, the silicone compound does not adsorb to the resin and can continue to be adsorbed and oriented on the surface of the easy-adhesion layer.

Since the surface conditioner for an easy-adhesion layer according to the present invention is a polyether-modified silicone, it is possible to impart appropriate polarity to the side chains and obtain high compatibility with resins. Polyether-modified silicone is a compound in which a polyoxyalkylene group is introduced into a part of the siloxane bond of a polysiloxane compound, and a polyoxyalkylene group is introduced into an arbitrary position such as a side chain or end of the siloxane skeleton. can be used, but it is preferable to use one in which a polyoxyalkylene group is introduced into the side chain. An example of a preferred general formula is shown below.

(In the formula, R ₁ represents a hydrogen atom or an alkyl group. R ₂ and R ₃ represent an alkyl group. m, n, x and y represent an integer of 1 or more.)

The polyether-modified silicone used in the present invention includes polyether _- modified polydimethylsiloxane (R3 is a methyl group), or one of the dimethyl groups of the polyether-modified polydimethylsiloxane is partially or wholly a long-chain alkyl group. A polyether-modified polymethylalkylsiloxane substituted with a group (R3 is a long _- chain alkyl group) is preferably used.

Specific examples include polydimethylsiloxane modified with polyethylene oxide, polypropylene oxide, polybutylene oxide or mixtures thereof. The surface tension and polarity of these polyether-modified polydimethylsiloxanes can be adjusted by appropriately changing the amount and mixing ratio of polyethylene oxide, polypropylene oxide or polybutylene oxide.

Further, in the polyether-modified polydimethylsiloxane having polyoxyalkylene in the side chain of polydimethylsiloxane, a linear block in which the structural portion of polydimethylsiloxane and the structure having a polyoxyalkylene chain are alternately and repeatedly bonded Copolymers are preferred.

Regarding the degree of polymerization in the general formula (1), m is preferably an integer of 1 to 4, n is preferably an integer of 1 to 100, and x and y are integers of 1 to 1000. is preferred.

Commercially available polyether-modified silicones may be used, for example, BYK (registered trademark)-300, BYK-302, BYK-306, BYK-307, BYK-320, BYK-325 manufactured by BYK-Chemie Japan Co., Ltd. , BYK-330, BYK-331, BYK-333, BYK-337, BYK-344, BYK-375, BYK-377, BYK-378, BYK-3450, BYK-UV3500, BYK-UV3510, Shin-Etsu Chemical Co., Ltd. KF-945, KF-352A, KF-640, KF-351A, KF-354L, KF-6011, KF-6015, KF-6020 manufactured by Dow Toray Industries, Inc. XIAMETER (registered trademark) OFX-0193 Fluid, etc. can be mentioned.

In addition, the kinematic viscosity of the polyether-modified silicone at 25° C. is preferably 40 mm ² /s or more, more preferably 50 mm ² /s or more, still more preferably 60 mm ² /s or more, from the same viewpoint as above, and , preferably 1000 mm ² /s or less, more preferably 900 mm ² /s or less, still more preferably 800 mm ² /s or less. The kinematic viscosity can be obtained with an Ubbelohde viscometer.

[HLB value]
"HLB value" refers to a numerical value representing the balance between hydrophilic groups and hydrophobic groups in a molecule. Specifically, 0 is assigned to those having no hydrophilic group, 20 is assigned to those having only hydrophilic groups but no hydrophobic groups, and those having both hydrophilic and hydrophobic groups in one molecule take values in between.
"HLB" is an abbreviation for Hydrophile Lipophile Balance.

The HLB value of one compound can be determined, for example, by Griffin's method represented by the following formula (1). However, the hydrophilic part means an aggregate of hydrophilic groups in the molecule.
Formula (1) HLB value = 20 × sum of formula weights of hydrophilic moieties/molecular weight

The HLB value of the polyether-modified silicone according to the present invention is characterized by being in the range of 5-15. If the HLB value is less than 5, the hydrophilic part is small and the hydrophobicity is high, so the polyether-modified silicone in the easy-adhesion layer tends to aggregate on the highly hydrophobic polyolefin resin, and is oriented and adsorbed on the easy-adhesion layer surface. difficult. In addition, the aggregation causes poor appearance. If the HLB value is more than 15, the hydrophilicity is high, so that it is easily dissolved in the organic solvent used in forming the hard coat layer, and is difficult to be oriented and adsorbed on the surface of the easy-adhesion layer. Also, by setting the HLB value within the above range, the compatibility with the resin used for forming the hard coat layer can be enhanced.

The HLB value of the polyether-modified silicone according to the present invention can be adjusted by appropriately changing the structure of the polyoxyalkylene group.

Further, the HLB value is more preferably in the range of 5-15, more preferably in the range of 8-12.

[Content]
The content (solid content ratio) per unit thickness of the polyether-modified silicone is preferably 1 to 6% by mass, more preferably 2%, based on the total mass per unit thickness of the easy-adhesion layer material. ~5% by mass. When the content of the polyether-modified silicone is 1% by mass or more with respect to the total mass per unit thickness of the easy-adhesion layer material, it can be densely oriented on the easy-adhesion layer surface, resulting in excellent adhesion. Further, when the content is 6% by mass or less, aggregation of the surface control agent can be suppressed, so that the appearance of the entire optical film is excellent when the easy-adhesion layer is formed by coating.

Moreover, the content (solid content ratio) Mp of the polyether-modified silicone, which is a surface conditioner in the easy-adhesion layer, is represented by the following formula (I).
Formula (I):
Mp = (thickness of easy-adhesion layer x solid content ratio per unit thickness of surface conditioner contained in easy-adhesion layer)

Mp is preferably in the range of 0.3-6. When Mp is 0.3 or more, the difference in surface tension is small at the interface between the base film and the coating film when the composition for forming an easily adhesive layer is applied to the base film, and repelling is less likely to occur. Moreover, when Mp is 6 or less, the surface conditioner is difficult to aggregate. Therefore, when Mp is within the above range, an optical film with high transparency can be obtained.
Mp is more preferably in the range of 0.5-4, more preferably in the range of 1-3.

<1.1.3 Other Additives>
In addition to the surface conditioner described above, any additive may be used in the easy-adhesion layer according to the present invention, if necessary.
Specific examples of additives include photopolymerization initiators, thermal polymerization initiators, polymerization accelerators, viscosity modifiers, slip agents, dispersants, plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, UV absorbers, flame retardants, colorants, antistatic agents, compatibilizers, cross-linking agents, and the like. The type and amount of additive used can be appropriately set according to the purpose. For example, the amount of the additive used is preferably 30 parts by mass or less, more preferably 20 parts by mass or less with respect to 100 parts by mass of the total solid content in the easy-adhesion layer.

Also, any appropriate fine particles can be used to impart anti-blocking properties. Specific examples of fine particles include Nippon Shokubai Co., Ltd., "Seahoster Series (registered trademark)" KE-P20, KE-P30, developed product KE-W20, "Eposter Series (registered trademark)" MX100W, and the like. The particle size of the fine particles is preferably in the range of 50-500 nm, more preferably in the range of 100-300 nm. Within the above range, both transparency and anti-blocking properties of the easy-adhesion layer can be achieved.

<1.1.4 Method for Forming Easily Adhesive Layer>
The easy-adhesion layer according to the present invention can be formed using a composition for forming an easy-adhesion layer. The easily adhesive layer-forming composition may be, for example, a commercially available solution or dispersion, may be used by adding a solvent to a commercially available solution or dispersion, or may be used by dissolving or dispersing the solid content in a solvent. You can use it with

In the present invention, the composition for forming an easy-adhesion layer is prepared by mixing the water-based polyolefin resin, the surface conditioner for the easy-adhesion layer, and, if necessary, the additive and a solvent by a conventionally known method. preferably. As the solvent, for example, water may be used alone, or a combination of known organic solvents such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, methyl ethyl ketone, and dimethylformamide and water may be used.

Next, the obtained composition for forming an easy-adhesion layer is applied, specifically applied, to a base film to be described later. As the coating method, known methods such as spin coating, knife coating, roll coating, bar coating, blade coating, die coating, gravure coating, etc. are used to apply and dry to a predetermined thickness. method can be used.

Conditions for forming the easy-adhesion layer are, for example, as follows.
The composition for forming an easy adhesion layer is applied onto a base film and dried at a temperature of usually 50 to 150° C., preferably 60 to 100° C. for usually 1 to 10 minutes, preferably 2 to 7 minutes, to form a coating film. Form.

When coating the substrate film, the surface of the substrate film may be subjected to solvent modification, corona treatment, plasma treatment, or the like as preliminary treatment for improving wettability.

The total solid content concentration of the composition for forming an easy-adhesion layer may vary depending on the kind, solubility, coating viscosity, wettability, thickness after drying, etc. of the easy-adhesion layer-forming material. In order to obtain an easily adhesive layer with high surface uniformity, the total solid content concentration is preferably 1 to 100 parts by mass, more preferably 1 to 50 parts by mass, relative to 100 parts by mass of the solvent. .

Any appropriate viscosity can be adopted as the viscosity of the easily adhesive layer-forming composition within a range that allows application. The viscosity is preferably 1 to 50 mPa·sec, more preferably 2 to 10 mPa·sec, when measured at a shear rate of 1000 (1/s) at 23°C. If it is said range, the easy-adhesion layer excellent in surface uniformity can be formed.

The substrate film laminated with the easy-adhesion layer can be stretched at an arbitrary ratio as necessary. The stretching direction may be a horizontal direction, a vertical direction, or an oblique direction uniaxially or biaxially with respect to the conveying direction. The base film may be stretched before forming the easy-adhesive layer, after forming the easy-adhesive layer, or as necessary. good too. The stretching conditions are as described above.

<1.2 Hard coat layer>
The hard coat layer according to the present invention is characterized in that it contains a surface modifier, and the surface modifier has a weight-average molecular weight of 4,000 or less. By having a hard coat layer, it is possible to provide an optical film with high scratch resistance and impact resistance.

The hard coat layer according to the present invention preferably exhibits a hardness of "HB" or higher in the pencil hardness test specified in JISK5600-2014. From the viewpoint of film strength, it is preferably in the range of 0.5 to 4 μm, more preferably in the range of 1 to 3 μm.

<1.2.1 Resin for hard coat layer>
As the resin for the hard coat layer, it is preferable to use an active energy ray-curable resin that is cured by irradiation with an active energy ray from the viewpoint that it can be formed at room temperature in a short period of time. Such a resin is preferably a resin containing a monomer having an ethylenically unsaturated double bond. As the active energy ray, for example, ultraviolet rays and electron beams can be used, and from the viewpoint of mechanical film strength (scratch resistance, impact resistance, and pencil hardness), ultraviolet rays are more preferable.

An acrylic material is preferably used as the active energy ray-curable resin. The acrylic material is synthesized from a monofunctional or polyfunctional (meth)acrylate compound such as a polyhydric alcohol (meth)acrylic acid ester, a diisocyanate, a polyhydric alcohol, and a (meth)acrylic acid hydroxy ester. A polyfunctional urethane (meth)acrylate compound such as can be used. In addition to these, polyether resins, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. having acrylate-based functional groups can be used.

Among these resins, those that are cured by ultraviolet rays are more preferable, and in particular, ultraviolet-curable acrylate-based resins, ultraviolet-curable urethane acrylate-based resins, ultraviolet-curable polyester acrylate-based resins, ultraviolet-curable epoxy acrylate-based resins, and ultraviolet-curable resins. A polyol acrylate-based resin, an ultraviolet-curable epoxy resin, or the like is preferably used, and an ultraviolet-curable acrylate-based resin is particularly preferable.

The hard coat layer is formed using, for example, a hard coat layer-forming composition containing an active energy ray-curable resin, a polymerization initiator, and a solvent. As the solvent contained in the hard coat layer-forming composition, a solvent that dissolves or swells the easy-adhesion layer is preferable. This makes it easier for the composition for forming a hard coat layer to permeate from the surface of the easy-adhesion layer into the inside, thereby improving the adhesion between the easy-adhesion layer and the hard coat layer.

<1.2.2 Surface conditioner for hard coat layer>
The surface modifier contained in the hard coat layer according to the present invention (also referred to as a hard coat layer surface modifier) is characterized by having a weight-average molecular weight of 4,000 or less. The surface conditioner is, like the surface conditioner for the easy-adhesion layer, added for the purpose of imparting good wettability and uniformity to the coating film and smoothness and slipperiness of the coating film surface. As the compound to be used, a compound having both a hydrophilic group and a hydrophobic group in the molecule is preferable.

The hard coat layer according to the invention is preferably formed directly on the easy-adhesion layer. More specifically, it is preferable to apply the composition for forming a hard coat layer onto the easily adhesive layer and cure the composition by irradiation with active energy rays. Therefore, from the viewpoint of improving the adhesion between the easy-adhesion layer and the hard coat layer, it is preferable that the hard coat layer is also formed smoothly with a uniform thickness on the easy-adhesion layer.

In addition, when the composition for forming a hard coat layer is directly applied onto the easy-adhesion layer, the surface of the easy-adhesion layer ceases to be a gas-liquid interface. It moves to be adsorbed on the surface of the hard coat layer, which is the liquid interface, and the surface state of the easy-adhesion layer changes.

The hard coat layer according to the present invention can be formed smoothly with a uniform thickness by adding a surface conditioner having a weight-average molecular weight of 4000 or less. Since it preferentially adsorbs and aligns on the surface of the hard coat layer, the hard coat layer can be formed without changing the surface state of the easy-adhesion layer.

That is, by setting the weight-average molecular weight of the hard coat layer surface conditioner to a relatively small value of 4000 or less, the hard coat layer surface conditioner can move freely in the composition for forming the hard coat layer. , easily adsorbed and oriented on the surface of the hard coat layer.

Therefore, when the weight average molecular weight of the hard coat layer surface conditioner is 4000 or less, it can be preferentially adsorbed and oriented on the surface of the hard coat layer as compared with the easy adhesion layer surface conditioner. Particularly preferably, the weight average molecular weight is within the range of 800-3000, more preferably within the range of 800-1500.

The weight average molecular weight according to the present invention refers to the weight average molecular weight measured by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and converted to polystyrene. If it cannot be measured with tetrahydrofuran, use dimethylformamide. If it cannot be measured, use hexafluoroisopropanol. If it cannot be measured with hexafluoroisopropanol, use 2-chloronaphthalene.

The type of compound used as the surface modifier for the hard coat layer according to the present invention is not particularly limited, and examples thereof include silicone-, acrylic-, fluorine-, and acetylene-based compounds having a weight-average molecular weight of 4,000. The following commercial products can also be used.

From the viewpoint of adhesion, the compound used as the surface conditioner for the hard coat layer according to the present invention is preferably the same compound as the polyether-modified silicone used as the surface conditioner for the easy-adhesion layer.

When the composition for forming a hard coat layer is directly applied onto the easy-adhesion layer, the easy-adhesion layer surface conditioner adsorbed and oriented on the easy-adhesion layer surface is applied to the hard-coat layer surface, which is a new air-liquid interface. In some cases, the surface conditioner for the hard coat layer may be adsorbed and oriented on the surface of the easy-adhesion layer (the interface between the easy-adhesion layer and the hard coat layer) instead of the hard-coat layer surface conditioner.
Such a phenomenon can be partially suppressed by relatively reducing the weight-average molecular weight of the surface conditioner for the hard coat layer to 4000 or less, but it is difficult to completely suppress it.
However, if the surface control agent for the hard coat layer is the same compound as the surface control agent for the easy-adhesion layer, even if the surface control agent migrates, the same compound will remain at the interface between the easy-adhesion layer and the hard coat layer. Excellent adhesion due to orientation. In addition, "it is the same compound" means that it is a compound of the same structure and molecular weight.

[Content]
The content (solid content ratio) per unit thickness of the hard coat layer surface conditioner is preferably 0.3 to 3% by mass with respect to the total mass per unit thickness of the material for the hard coat layer. , more preferably 0.4 to 2% by mass. When the hard coat layer surface modifier is 0.3% by mass or more with respect to the total mass per unit thickness of the hard coat layer material, the hard coat layer surface, which is the gas-liquid interface, is the hard coat layer surface. Excellent adhesion because it can be filled with a modifier. Further, when the content is 3% by mass or less, aggregation of the surface control agent can be suppressed, so that the appearance of the entire optical film when a hard coat layer is formed by coating is excellent.

Further, the content (solid content ratio) Mh of the polyether-modified silicone, which is a surface modifier in the hard coat layer, is represented by the following formula (II).
Formula (II):
Mh = (thickness of hard coat layer x ratio of solid content per unit thickness of surface modifier contained in hard coat layer)

Mh is preferably in the range of 0.15-12. When Mh is 0.15 or more, the difference in surface tension is small at the interface between the easy-adhesion layer and the coating film when the composition for forming a hard coat layer is applied to the easy-adhesion layer, and cissing is less likely to occur. Moreover, when Mh is 12 or less, the surface conditioner is difficult to aggregate. Therefore, when Mh is within the above range, an optical film with high transparency can be obtained.
Mh is more preferably in the range of 0.5-8, more preferably in the range of 1-3.

Furthermore, when Mh/Mp is within the range of 0.02 to 40, an optical film with high transparency can be obtained.

<1.2.3 Other Additives>
In addition, the composition for forming a hard coat layer has properties of increasing the hardness of the hard coat layer, suppressing curing shrinkage, preventing blocking, controlling the refractive index, imparting antiglare properties, and properties of the hard coat layer surface. Depending on the purpose of controlling, conventionally known fine particles, dispersants, antistatic agents, silane coupling agents, thickeners, anti-coloring agents, coloring agents (pigments, dyes), antifoaming agents, flame retardants, Adhesion imparting agents, polymerization inhibitors, antioxidants, surface modifiers, etc. may be added. The composition for forming a hard coat layer may also contain a photosensitizer, and specific examples thereof include n-butylamine, triethylamine, poly-n-butylphosphine and the like.

Furthermore, for the purpose of imparting light resistance, it is preferable to add an ultraviolet absorber or a dye compound. Examples of the ultraviolet absorber include triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, oxybenzophenone-based ultraviolet absorbers, salicylic acid ester-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. These can be used singly or in combination of two or more.
Examples of dye compounds include azomethine-based compounds, indole-based compounds, cinnamic acid-based compounds, pyrimidine-based compounds, porphyrin-based compounds, and dicyanomethine-based compounds.

In particular, the hard coat layer preferably contains fine particles. The content of fine particles is preferably fine particles:active energy ray-curable resin=100:100 to 400:100. By including the fine particles in such a content, the dimensional variation of the hard coat layer can be reduced. The fine particles here are not particularly limited, but are preferably fine particles composed of a metal oxide (hereinafter also referred to as "metal oxide particles"). Examples of metal oxides used herein include silica, alumina, zirconia, titanium oxide, antimony pentoxide, and the like. Among these, the metal oxide particles are preferably composed of silica. The silica fine particles may be hollow particles having a hollow inside.

The fine particles are preferably coated with a polymer silane coupling agent. By coating the surface of the fine particles with the polymer silane coupling agent, the fine particles can be uniformly dispersed in the composition for forming the hard coat layer. The average particle diameter of the fine particles coated with the polymer silane coupling agent is preferably 5-500 nm, more preferably 10-200 nm. By using fine particles having such an average particle size, the optical properties of the hard coat layer can be enhanced.

The polymer silane coupling agent is prepared by reacting a polymerizable monomer with a silane coupling agent (reactive silane compound). The polymerizable monomer includes a monomer having an ethylenically unsaturated double bond, preferably a monomer selected from (meth)acrylic acid and its derivatives. As the reactive silane compound, a hydrolyzable silane compound in which three alkoxy groups and one functional group are bonded to a silicon atom is preferred. Examples of functional groups bonded to silicon atoms include groups having one or more groups selected from (meth)acryloxy groups, epoxy groups (glycidide groups), urethane groups, amino groups, fluoro groups, and mercapto groups. be done.

The polymer silane coupling agent can be produced, for example, according to the method for producing a reaction product of a polymerizable monomer and a reactive silane compound disclosed in JP-A-11-116240. The number average molecular weight of the polymer silane coupling agent is preferably 2,500 to 150,000, more preferably 2,000 to 100,000 in terms of polystyrene.

A method for coating the surface of fine particles with a polymer silane coupling agent will be described by taking silica fine particles as an example. First, a dispersion is prepared by dispersing silica fine particles and a polymer silane coupling agent in an organic solvent. An alkali is added to this dispersion to generate OH groups on the surface of the silica fine particles, and the polymer silane coupling agent is adsorbed on the OH groups. Alternatively, the OH group and the OH group of the polymer silane coupling agent are combined by a dehydration reaction. Finally, the silica fine particles to which the polymer silane coupling agent is adsorbed or bonded are separated from the dispersion and dried to obtain the silica fine particles coated with the polymer silane coupling agent.

<1.2.4 Method for forming hard coat layer>
The method for preparing the hard coat layer-forming composition is not particularly limited as long as the solid components contained in the hard coat layer can be uniformly mixed with the solvent. It can be prepared by mixing or dissolving using known devices such as kneaders and mixers.

The hard coat layer-forming composition is applied to the surface of the easy adhesion layer, and the hard coat layer is formed by curing the active energy ray-curable resin in the coating film. As a method for applying the composition for forming a hard coat layer, conventionally known methods can be applied without particular limitation. For example, a micro gravure coating method is preferred when forming a uniform thin film layer, and a die coating method is preferred when a thick film layer needs to be formed. After removing the solvent from the coating film as necessary, the hard coat layer is obtained by curing the active energy ray-curable resin by irradiation with active energy rays.

<1.3 Base film>
The base film according to the present invention is not particularly limited, and any film can be used, and the thickness is not particularly limited, but from the viewpoint of workability such as strength and handleability, thin film properties, etc. It is preferably in the range of 500 μm. The optical film of the present invention is provided in a polarizing plate and, from the viewpoint of functioning as a protective film, is formed of a thermoplastic resin material excellent in transparency, mechanical strength, thermal stability, water barrier properties, isotropy, etc. is preferred. A thermoplastic elastomer, a rubbery polymer, organic fine particles, inorganic fine particles, etc. may be contained as a film-forming component within a range that does not impair the effects of the present embodiment. In addition, the organic fine particles include rubber particles, which will be described in the later-described acrylic resin.

Therefore, the resin for the base film is not particularly limited, but it is preferably a thermoplastic resin. Combined (AS resin), polyamide resin, polyimide resin, polysulfone resin, polyethersulfone resin, polyolefin resin, cycloolefin resin, polyvinyl chloride resin, polyvinyl alcohol resin, polyvinyl butyral resin, epoxy resin, norbornene resin, fluorine resin, etc. mentioned.

The thermoplastic resin may be used alone or in combination of two or more. In addition to the thermoplastic resins described above, thermoplastic elastomers, rubbery polymers, organic fine particles, inorganic fine particles, and the like may be contained as film-forming components within a range that does not impair the effects of the present embodiment. In addition, the organic fine particles include rubber particles, which will be described in the later-described acrylic resin. Furthermore, other additives such as an antioxidant, a plasticizer, an antistatic agent, a release agent, a thickener, and an ultraviolet absorber may be included within a range that does not impair the effects of the present embodiment.

The base film may be a single layer or a laminated film of two or more layers. In the case of a laminated film having two or more layers, the thermoplastic resin used for forming each layer may be the same or different. As the method for producing the laminated film, conventionally known methods can be applied without particular limitation.

As the thermoplastic resin used for forming the base film, cycloolefin resin, cellulose ester resin, and acrylic resin are preferable from the viewpoint of transparency, mechanical strength, and the like. Of these, particularly preferred thermoplastic resins are cycloolefin resins that are less susceptible to moisture due to their low polarity and whose refractive index is less likely to change with wavelength.

<1.3.1 Resin for base film>
(Cycloolefin resin)
The cycloolefin resin used in the present invention preferably includes a (co)polymer having a structure represented by the following general formula (2).

In general formula (2), R ¹ to R ⁴ each independently represent a hydrogen atom, a hydrocarbon group, a halogen atom, a hydroxy group, an ester group, an alkoxy group, a cyano group, an amide group, an imide group, a silyl group, or a polar A hydrocarbon group substituted with a group (ie, a halogen atom, a hydroxy group, an ester group, an alkoxy group, a cyano group, an amide group, an imide group, or a silyl group). However, two or more of R ¹ to R ⁴ may be bonded together to form an unsaturated bond, a monocyclic ring or a polycyclic ring, and this monocyclic or polycyclic ring has a double bond. or may form an aromatic ring. R ¹ and R ² or R ³ and R ⁴ may form an alkylidene group. p and m are integers of 0 or more.

In general formula (2) above, R ¹ and R ³ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms, more preferably 1 to 4 carbon atoms, and particularly preferably 1 or 2 carbon atoms. R ² and R ⁴ are hydrogen atoms or monovalent organic groups, and at least one of R ² and R ⁴ is a polar group other than a hydrogen atom and a hydrocarbon group. m is an integer of 0 to 3, p is an integer of 0 to 3, more preferably m+p=0 to 4, more preferably 0 to 2, particularly preferably m=1 and p=0. A specific monomer in which m=1 and p=0 is preferable in that the resulting cycloolefin resin has a high glass transition temperature and excellent mechanical strength.

Examples of the polar group of the specific monomer include a carboxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, a cyano group, etc. These polar groups include a linking group such as a methylene group. may be connected via A polar group also includes a hydrocarbon group to which a polar divalent organic group such as a carbonyl group, an ether group, a silyl ether group, a thioether group, and an imino group is bonded as a linking group. Among these, a carboxy group, a hydroxy group, an alkoxycarbonyl group or an aryloxycarbonyl group is preferable, and an alkoxycarbonyl group or an aryloxycarbonyl group is particularly preferable.

Further, a monomer in which at least one of R ² and R ⁴ is a polar group represented by the formula —(CH ₂ ) _n COOR is preferred because the resulting cycloolefin resin has a high glass transition temperature, low hygroscopicity, and various materials. It is preferable in that it has excellent adhesion. In the above specific polar group formula, R is a hydrocarbon group having 1 to 12 carbon atoms, more preferably 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms, preferably an alkyl group.

Specific examples of copolymerizable monomers include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene and dicyclopentadiene. The cycloolefin preferably has 4 to 20 carbon atoms, more preferably 5 to 12 carbon atoms.

In this embodiment, the cycloolefin resin can be used alone or in combination of two or more.

The preferred molecular weight of the cycloolefin resin of the present embodiment is 0.2 to 5 dL/g, more preferably 0.3 to 3 dL/g, particularly preferably 0.4 to 1.5 dL/g in intrinsic viscosity [η]inh. The number average molecular weight (Mn) in terms of polystyrene measured by gel permeation chromatography (GPC) is 8000 to 100000, more preferably 10000 to 80000, particularly preferably 12000 to 50000, and the weight average molecular weight (Mw) is in the range of 20,000 to 300,000, more preferably 30,000 to 250,000, particularly preferably 40,000 to 200,000.

When the intrinsic viscosity [η] inh, the number average molecular weight and the weight average molecular weight are in the above ranges, the heat resistance, water resistance, chemical resistance and mechanical properties of the cycloolefin resin and the cycloolefin film of the present embodiment are improved. Formability is improved.

For the number average molecular weight, a value measured by high performance liquid chromatography under the following conditions is adopted.
Solvent: methylene chloride Column: Shodex K806, K805, K803G (three columns manufactured by Showa Denko Co., Ltd. were connected and used)
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Science)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 mL/min Temperature: 23°C
Calibration curve: standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) A calibration curve of 13 samples in the range of Mw = 500 to 2,800,000 was used. The 13 samples are preferably used at approximately equal intervals.

The glass transition temperature (Tg) of the cycloolefin resin of the present embodiment is usually 110°C or higher, preferably 110 to 350°C, more preferably 120 to 250°C, particularly preferably 120 to 220°C. . A Tg of 110° C. or higher is preferred because deformation is less likely to occur during use under high-temperature conditions or secondary processing such as coating and printing. On the other hand, by setting the Tg to 350° C. or lower, it is possible to avoid the case where molding becomes difficult, and to suppress the possibility of deterioration of the resin due to heat during molding.

For the cycloolefin resin, within a range that does not impair the effects of the present embodiment, for example, specific hydrocarbon resins described in JP-A-9-221577 and JP-A-10-287732, or known heat Plastic resins, thermoplastic elastomers, rubbery polymers, organic fine particles, inorganic fine particles, etc. may be blended, and specific wavelength dispersion agents, sugar ester compounds, antioxidants, release accelerators, rubber particles, plasticizers, ultraviolet rays, etc. Additives such as absorbents may also be included.

Moreover, a commercial item can be used preferably as a base film using a cycloolefin resin. Commercially available products are commercially available, for example, from JSR Corporation under the trade names of Arton (registered trademark) G (G7810, etc.), Arton F, Arton R, and Arton RX, and Zeonor from Nippon Zeon Co., Ltd. (Zeonor®) ZF14, ZF16, Zeonex® 250 or Zeonex 280 are commercially available and can be used.

(cellulose ester resin)
Cellulose ester resins used in the present invention preferably include, for example, triacetyl cellulose, cellulose acetate propionate, cellulose diacetate, cellulose acetate butyrate and the like. Moreover, together with the cellulose ester resin, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate resins, polyolefin resins such as polyethylene and polypropylene, norbornene resins, fluororesins, cycloolefin resins, and the like may be used in combination.

The cellulose ester used in the substrate film according to the present invention is preferably a carboxylic acid ester having about 2 to 22 carbon atoms, and may be an ester of an aromatic carboxylic acid or a lower fatty acid ester of cellulose. is preferred. Here, the "lower fatty acid" in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms.

Further, the acyl group bonded to the hydroxy group of the glucose unit constituting the cellulose ester may be a linear hydrocarbon group, a branched hydrocarbon group, or a cyclic hydrocarbon group. Alternatively, the acyl group may be substituted with another substituent. When the degree of substitution of the substituents bonded to the hydroxy group of the cellulose ester is the same, if the lower fatty acid has more than 7 carbon atoms, the birefringence decreases. The group preferably has 2 to 6 carbon atoms, more preferably 2 to 4 carbon atoms, and still more preferably 2 to 3 carbon atoms.

In the present invention, acyl groups derived from mixed acids can also be used for the cellulose ester, and acyl groups having 2 and 3 carbon atoms or acyl groups having 2 and 4 carbon atoms are preferably used. Specific examples of such cellulose esters include cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, and other mixed fatty acid esters of cellulose in which propionate groups or butyrate groups are bonded in addition to acetyl groups. can be used. The butyryl group forming the butyrate may be linear or branched. The cellulose ester is preferably cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, or cellulose acetate phthalate.

The retardation value of the substrate film can be appropriately controlled by the type of acyl group contained in the cellulose ester and the degree of substitution of the acyl group to the pyranose ring of the cellulose resin skeleton.

It is preferable that the substituents bonded to the hydroxy groups of the glucose units constituting the cellulose ester used in the substrate film simultaneously satisfy the following formulas (2) and (3).

Formula (2): 2.0≤X+Y≤3.0
Formula (3): 0≤Y≤2.0
In formula (2) above, X is the degree of substitution of the acetyl group, and in formulas (2) and (3), Y is the degree of substitution of the propionyl or butyryl group. By satisfying the above two formulas, it is possible to produce a base film exhibiting excellent optical properties. Among the above cellulose esters, triacetyl cellulose and cellulose acetate propionate are preferably used. Cellulose acetate propionate has an acetyl group substitution degree X of 1.0≦X≦2.5 and 0.1≦Y≦1.5 and 2.0≦X+Y≦3.0. preferable.

The degree of acyl substitution can be measured according to ASTM-D817-96. If the degree of substitution with the acyl group is too low, the hydroxy groups of the pyranose ring constituting the skeleton of the cellulose resin will have many unreacted portions, and many of the hydroxy groups will remain. For this reason, the retardation value of the base film changes depending on humidity, which is not preferable, and the ability of the polarizing plate protective film to protect the polarizer is lowered, which is not preferable.

The number average molecular weight of the cellulose ester is preferably 60,000 to 300,000, more preferably 70,000 to 200,000. By using a cellulose ester having such a number average molecular weight, the mechanical strength of the substrate film can be enhanced. As the number average molecular weight of this cellulose ester, a value measured by high performance liquid chromatography under the following conditions is adopted.

Solvent: Acetone Column: MPW × 1 (manufactured by Tosoh Corporation)
Sample concentration: 0.2 (mass/volume)%
Flow rate: 1.0 mL/min Sample injection volume: 300 μL
Standard sample: Standard polystyrene Temperature: 23°C
The cellulose used as a raw material for the cellulose ester is not particularly limited, but cotton linter, wood pulp, kenaf and the like can be mentioned. Also, cellulose esters obtained from these materials may be mixed in an arbitrary ratio and used.

When an acid anhydride such as acetic anhydride, propionic anhydride, or butyric anhydride is used as the acylating agent for the cellulose raw material, the reaction occurs with an organic acid such as acetic acid or an organic solvent such as dichloromethane and a protic catalyst such as sulfuric acid. done. When acid chlorides (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl) are used as acylating agents, basic compounds such as amines are used as catalysts. Acylation of cellulose raw materials can be synthesized by the method described in JP-A-10-45804.

In the above cellulose ester, the average degree of substitution of the acyl group at the 6-position of the glucose unit is preferably 0.5 to 0.9. The hydroxy group at the 6-position of the glucose unit constituting the cellulose ester has a primary hydroxy group with higher reactivity than the hydroxy groups at the 2- and 3-positions. The primary hydroxy groups preferentially form sulfate esters during the sulfuric acid-catalyzed production of cellulose esters. For this reason, in the esterification reaction of cellulose, by increasing the amount of sulfuric acid added as a catalyst, cellulose ester having a higher average degree of substitution of hydroxy groups at the 2- and 3-positions of glucose units than ordinary cellulose ester. can be obtained.

Moreover, in order to increase the average degree of substitution of the 2- and 3-position hydroxy groups, the cellulose ester may be tritylated, if necessary. By selectively protecting the hydroxy group at the 6-position of the glucose unit constituting the cellulose ester by tritylation, the hydroxy groups at the 2- and 3-positions of the glucose unit can be intensively esterified. Then, after esterifying the hydroxy groups at the 2-position and the 3-position of the glucose unit, the trityl group (protecting group) protecting the hydroxy group at the 6-position of the glucose unit is removed to obtain a hydroxy group at the 6-position of the glucose unit. It is possible to increase the average degree of substitution of 2- and 3-position hydroxy groups over groups. As such an esterification method, it is preferable to use a cellulose ester produced by the method described in JP-A-2005-281645.

When acetylcellulose is used as the cellulose ester, it is necessary to extend the acetylation reaction time in order to increase the acetylcellulose acetylation rate. However, if the reaction time for the acetylation reaction is lengthened, scission of the cellulose chain, decomposition of the acetyl group, and the like occur, which is not preferable. Therefore, in order to suppress decomposition of acetylcellulose while increasing the degree of acetylation of cellulose acetylate, it is preferable to set the reaction time of the acetylation reaction within a specific range. However, it is difficult to uniformly determine the preferred numerical range of the reaction time because the optimum reaction time varies greatly depending on the reaction apparatus, reaction equipment, other reaction conditions, and the like.

Therefore, it is preferable to use the value of weight average molecular weight (Mw)/number average molecular weight (Mn), which is one index of the degree of reaction, instead of the reaction time. Cellulose ester has a broader molecular weight distribution as decomposition progresses in the same manner as decomposition of ordinary polymers. can be done. For example, by specifying the degree of reaction by weight average molecular weight (Mw)/number average molecular weight (Mn), in the process of acetylating cellulose triacetate, the reaction time for acetylation becomes too long and decomposition of cellulose triacetate progresses. Overshooting can be prevented and sufficient reaction time for acetylation can be ensured. The Mw/Mn ratio of the cellulose ester is preferably 1.4-5.0.

An example of a method for producing cellulose ester is shown below. 100 parts by mass of cotton linter as a cellulose raw material is pulverized, 40 parts by mass of acetic acid is added, and pretreatment activation is performed at 36° C. for 20 minutes. After that, 8 parts by mass of sulfuric acid, 260 parts by mass of acetic anhydride, and 350 parts by mass of acetic acid are added, and esterification is performed at 36° C. for 120 minutes. Acetyl cellulose is obtained by neutralizing with 11 parts by mass of a 24% magnesium acetate aqueous solution and then saponifying and maturing at 63° C. for 35 minutes. This acetylcellulose was stirred for 160 minutes at room temperature using a 10-fold aqueous solution of acetic acid (acetic acid:water=1:1 (mass ratio)), filtered and dried to obtain purified acetylcellulose having a degree of acetyl substitution of 2.75. obtain. This acetylcellulose has Mn of 92000, Mw of 156000, and Mw/Mn of 1.7. Similarly, cellulose esters having different substitution degrees and Mw/Mn ratios can be synthesized by adjusting the esterification conditions (temperature, time, stirring) and hydrolysis conditions of the cellulose ester.

The cellulose ester synthesized by the above method is preferably purified to remove low-molecular-weight components, and preferably filtered to remove non-acetylated or low-acetylated components. Further, when the cellulose ester is a mixed acid cellulose ester, it can be obtained by the method described in JP-A-10-45804.

Moreover, the cellulose ester preferably does not contain metals such as iron (Fe), calcium (Ca), and magnesium (Mg). This is because these metal ions form an insoluble nucleus by forming a salt with a polymer decomposition product or the like containing an organic acidic group. It is believed that these trace metal components are contained in the cellulose ester derived from the water used in the manufacturing process.

Iron contained in the cellulose ester is preferably 1 ppm or less. Calcium contained in the cellulose ester is preferably 60 ppm or less, more preferably 0 to 30 ppm. Calcium may form complexes with acidic components such as carboxylic or sulfonic acids, and may also form complexes with many ligands. These complexes may form scum (insoluble sediment, turbidity) derived from insoluble calcium. Magnesium contained in the cellulose ester is preferably 0 to 70 ppm, more preferably 0 to 20 ppm. Formation of insoluble matter can be suppressed by controlling magnesium to 70 ppm or less.

The content of the above metals is determined by decomposing absolute dry cellulose ester into sulfuric acid with a microdigest wet decomposer, followed by pretreatment with alkali fusion, and then measuring the cellulose ester after pretreatment with ICP-AES (Inductively Coupled Plasma Emission Spectroscopy). Identified by analysis using an analyzer).

Moreover, a commercial item can be preferably used as a base film using a cellulose ester resin. Commercially available products include, for example, Konica Minolta Tuck KC8UX, KC4UX, KC8UY, KC4UY, KC6UA, KC4UA, KC2UA, KC4UE and KC4UZ, KC4CT1 and KC2CT1 (manufactured by Konica Minolta). The refractive index of the cellulose ester film is preferably 1.45-1.55. The refractive index can be measured according to JISK7142-2008.

(acrylic resin)
Acrylic resins are resins composed of (co)polymers obtained by (co)polymerizing monomers selected from (meth)acrylic acid and derivatives thereof. A unit derived from a monomer in a (co)polymer is referred to as a “structural unit”.

In the present embodiment, "(meth)acrylic" refers to both "acrylic" and "methacrylic", "(meth)acrylate" refers to both "acrylate" and "methacrylate", and "( "meta) acryloyl" refers to both "acryloyl" and "methacryloyl". For example, "urethane (meth)acrylate" indicates both "urethane acrylate" and "urethane methacrylate."

For the acrylic resin used for the base film, the types and combinations of monomers and the composition of the monomers are selected according to the required physical properties. From the viewpoint of adjusting the equilibrium moisture content of the substrate film within a predetermined range and improving the brittleness, the acrylic resin will be described below using a molecularly designed acrylic resin as an example. The resin is not limited to this. The acrylic resin preferably contains, for example, a structural unit (U1) derived from methyl methacrylate, a structural unit (U2) derived from phenylmaleimide, and a structural unit (U3) derived from an acrylic acid alkyl ester.

The content of the structural unit (U1) derived from methyl methacrylate is preferably 50 to 95% by mass, more preferably 70 to 90% by mass, based on the total structural units constituting the acrylic resin.

The structural unit (U2) derived from phenylmaleimide has moderate polarity, and thus can increase affinity with water. In addition, since the structural unit (U2) derived from phenylmaleimide has a relatively bulky structure, it can have microvoids through which moisture can move in the resin matrix. As a result, it is possible to improve the moisture mobility and dischargeability of the base film.

The content of the structural unit (U2) derived from phenylmaleimide is preferably 1 to 25% by mass based on the total structural units constituting the acrylic resin. When the content of the structural unit (U2) derived from phenylmaleimide is 1% by mass or more, it has an appropriate polarity, so it not only has an affinity with water molecules, but also creates microscopic voids through which water molecules can move. Since it has a sufficient amount, it is easy to increase the equilibrium moisture content. When the content of the structural unit (U2) derived from phenylmaleimide is 25% by mass or less, the brittleness of the base film is less likely to be impaired. From the above viewpoint, the content of the structural unit (U2) derived from phenylmaleimide is more preferably 7 to 15% by mass.

The structural unit (U3) derived from an alkyl acrylate ester has, for example, a good affinity with rubber particles in which the polymer constituting the shell portion includes a structural unit derived from butyl acrylate, which will be described later. can increase the dispersibility of

The alkyl acrylate is preferably an alkyl acrylate having 1 to 7 carbon atoms, preferably 1 to 5 carbon atoms in the alkyl portion. Examples of acrylic acid alkyl esters include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, and the like.

The content of the structural unit (U3) derived from alkyl acrylate is preferably 1 to 25% by mass based on the total structural units constituting the acrylic resin. When the content of the structural unit (U3) derived from the alkyl acrylate is 1% by mass or more, the acrylic resin can be imparted with appropriate flexibility, so that the film does not become too brittle and is difficult to break. When the content of the structural unit (U3) derived from an alkyl acrylate ester is 25% by mass or less, the Tg of the acrylic resin does not decrease excessively, so that the heat resistance of the substrate film is not easily impaired, and mechanical strength is also less likely to be compromised. From the above viewpoint, the content of the structural unit derived from the acrylic acid alkyl ester is more preferably 5 to 15% by mass.

The ratio of the structural unit (U2) derived from phenylmaleimide to the total amount of the structural unit (U2) derived from phenylmaleimide and the structural unit (U3) derived from an acrylic acid alkyl ester is 20 to 70% by mass. is preferred. When the ratio is 20% by mass or more, the heat resistance of the base film is likely to be enhanced, and when it is 70% by mass or less, the base film does not become too brittle.

The glass transition temperature (Tg) of the acrylic resin is preferably 110°C or higher, more preferably 120 to 150°C. When the Tg of the acrylic resin is within the above range, the heat resistance of the substrate film can be easily increased. In order to adjust the Tg of the acrylic resin, for example, it is preferable to adjust the content of the structural unit (U2) derived from phenylmaleimide or the structural unit (U3) derived from an acrylic acid alkyl ester.

The weight average molecular weight (Mw) of the acrylic resin is preferably 500,000 or more. When the weight-average molecular weight of the acrylic resin is 500,000 or more, the viscosity of the dope used for solution casting does not become too low, which not only suppresses aggregation of the rubber particles but also reduces the flatness of the surface of the base film. can also be suppressed. Furthermore, when the weight average molecular weight of the acrylic resin is 500,000 or more, sufficient mechanical strength (toughness) can be imparted to the base film. From the above viewpoint, the weight average molecular weight of the acrylic resin is more preferably 500,000 to 3,000,000, further preferably 600,000 to 2,000,000. A weight average molecular weight can be measured by the method similar to the above-mentioned.

The acrylic resin content is preferably 60% by mass or more, more preferably 70% by mass or more, relative to the base film.

When the base film is composed mainly of an acrylic resin, it may contain rubber particles having a function of imparting toughness (flexibility) to the base film. A rubber particle is a particle comprising a rubber-like polymer. A rubber-like polymer is a soft crosslinked polymer having a glass transition temperature of 20° C. or lower. Examples of such crosslinked polymers include butadiene crosslinked polymers, (meth)acrylic crosslinked polymers, and organosiloxane crosslinked polymers. Among them, a (meth)acrylic crosslinked polymer is preferable, and an acrylic crosslinked polymer (acrylic rubber-like polymer) is preferable from the viewpoint that the difference in refractive index from that of the acrylic resin is small and the transparency of the base film is not easily impaired. more preferred.

The rubber particles are preferably particles containing an acrylic rubber-like polymer. An acrylic rubber-like polymer is a crosslinked polymer containing a structural unit derived from an acrylic acid ester as a main component. Containing as a main component means that the content of the structural unit derived from the acrylic acid ester is 40% by mass or more. An acrylic rubber-like polymer includes a structural unit derived from an acrylic acid ester, a structural unit derived from another monomer copolymerizable therewith, and two or more radically polymerizable groups (non-conjugated groups) in one molecule. It is preferably a crosslinked polymer containing a structural unit derived from a polyfunctional monomer having a reactive double bond.

The glass transition temperature (Tg) of the rubber-like polymer is preferably 0° C. or lower, more preferably -10° C. or lower. When the glass transition temperature (Tg) of the rubber-like polymer is 0° C. or lower, the film can be imparted with appropriate toughness. The glass transition temperature (Tg) of the rubbery polymer is measured by the same method as described above.

The particles containing the acrylic rubber-like polymer may be core-shell type particles having a core containing the acrylic rubber-like polymer and a shell covering the core. The shell preferably contains a methacrylic polymer that is graft-bonded to the acrylic rubber-like polymer and that contains, as a main component, a structural unit derived from a methacrylic acid ester.

The average particle size of the rubber particles can be obtained by measuring the dispersed particle size of the rubber particles in the dispersion with a zeta potential/particle size measuring system (ELSZ-2000ZS, manufactured by Otsuka Electronics Co., Ltd.). The average particle size of the rubber particles is preferably in the range of 100-300 nm. Although the content of the rubber particles is not particularly limited, it is preferably 5 to 25% by mass, more preferably 5 to 15% by mass, based on the base film.

<1.3.2 Method for producing base film>
The base film according to the present invention can be produced by a known forming method such as a melt casting method, a solution casting method, or a calendering method. A melt casting method or a solution casting method is preferably used, and a solution casting method is particularly preferred.

Specifically, a production method including the following steps (1) to (3) is used to produce the base film by the solution casting method. Further, the production method preferably has step (4).
(1) A step of obtaining a dope containing a film-forming component containing a thermoplastic resin, and optionally the above additives and a solvent (2) Casting the obtained dope on a support, drying and peeling (3) Drying the obtained film while stretching it as necessary (4) Winding the obtained base film to obtain a roll body

Regarding Step (1) A dope is prepared by dissolving or dispersing the film-forming component containing the thermoplastic resin and, if necessary, the above additives in a solvent.

The solvent used for the dope contains at least an organic solvent (good solvent) capable of dissolving the thermoplastic resin. Moreover, when using an additive, it is preferable that the organic solvent has a high solubility for the additive. Examples of good solvents include chlorinated organic solvents such as dichloromethane; and non-chlorinated organic solvents such as methyl acetate, ethyl acetate, acetone, tetrahydrofuran. Among them, dichloromethane is preferred.

The solvent used for the dope may further contain a poor solvent. Examples of poor solvents include linear or branched aliphatic alcohols having 1 to 4 carbon atoms. When the ratio of alcohol in the dope becomes high, the film-like material tends to gel and is easily peeled off from the metal support. Examples of linear or branched aliphatic alcohols having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol and tert-butanol. Among these, ethanol is preferred because of its high dope stability, relatively low boiling point, and good drying properties.

Regarding Step (2) The obtained dope is cast on a support. Casting of the dope can be performed by discharging from a casting die.

The solvent in the dope cast on the support is then evaporated and dried. The dried dope is peeled off from the support to obtain a film.

The amount of residual solvent in the dope when peeled from the support (the amount of residual solvent in the film after peeling) is, for example, preferably 20% by mass or more, more preferably 20 to 30% by mass. When the residual solvent amount at the time of peeling is 30% by mass or less, it is easy to suppress excessive stretching of the film-like material due to peeling.

The residual solvent amount of the dope at the time of peeling is defined by the following formula (4). The same applies to the following.
Formula (4) Amount of residual solvent in dope (% by mass)=(mass of dope before heat treatment−mass of dope after heat treatment)/mass of dope after heat treatment×100
Note that the heat treatment for measuring the amount of residual solvent means heat treatment at 140° C. for 30 minutes.

The residual solvent amount at the time of stripping can be adjusted by the drying temperature and drying time of the dope on the support, the temperature of the support, and the like.

Regarding Step (3) The resulting film-like material is dried. Drying may be performed in one step or in multiple steps. Moreover, you may perform drying, extending|stretching as needed.

For example, the drying process of the film-like material includes a process of pre-drying the film-like material (pre-drying process), a process of stretching the film-like material (stretching process), and a process of drying the film-like material after stretching (main drying process). drying step).

(Pre-drying step)
The pre-drying temperature (drying temperature before stretching) can be higher than the stretching temperature. Specifically, when the glass transition temperature of the thermoplastic resin is Tg, it is preferably (Tg-50) to (Tg+50)°C. When the pre-drying temperature is (Tg-50) ° C. or higher, the solvent is easily volatilized appropriately, so it is easy to improve the transportability (handling property). , the stretchability in the subsequent stretching process is less likely to be impaired. The initial drying temperature can be measured as (a) the temperature inside the stretching machine or the ambient temperature such as the temperature of hot air when the film is dried by non-contact heating while being conveyed by a tenter stretching machine or rollers.

(Stretching process)
The stretching may be carried out according to the required optical properties, for example, the retardation value, preferably in at least one direction, and in two directions perpendicular to each other (for example, the width direction (TD direction) of the film). and biaxial stretching in the transport direction (MD direction) orthogonal thereto).

The draw ratio in producing the base film is preferably 5 to 100%, more preferably 20 to 100%. In the case of biaxial stretching, the stretching ratio in each direction is preferably within the above ranges.

The draw ratio (%) is defined by the following formula (5).
Formula (5) Stretch ratio (%) = (stretching direction size of film after stretching - stretching direction size of film before stretching) / (stretching direction size of film before stretching) × 100
In addition, when biaxially stretching, it is preferable to set it as the said draw ratio about each of TD direction and MD direction.

The stretching temperature (drying temperature during stretching) is preferably Tg (° C.) or higher, where Tg is the glass transition temperature of the thermoplastic resin, and is (Tg+10) to (Tg+50)° C. is more preferable. When the stretching temperature is Tg (° C.) or higher, preferably (Tg+10)° C. or higher, the solvent is easily volatilized appropriately, so that the stretching tension is easily adjusted to an appropriate range. does not volatilize too much, so stretchability is less likely to be impaired. The stretching temperature during production of the base film can be, for example, 115° C. or higher. As for the stretching temperature, it is preferable to measure (a) the ambient temperature such as the temperature inside the stretching machine, as described above.

The amount of residual solvent in the filmy material at the start of stretching is preferably about the same as the amount of residual solvent in the filmy material at the time of peeling, for example, preferably 20 to 30% by mass, preferably 25 to 30% by mass. % is more preferred.

Stretching in the TD direction (width direction) of the film can be performed, for example, by fixing both ends of the film with clips or pins and widening the distance between the clips or pins in the traveling direction (tenter method). The film-like material can be stretched in the MD direction, for example, by a method (roll method) in which a plurality of rolls are provided with different peripheral speeds and the difference in peripheral speeds of the rolls is utilized.

(Main drying process)
From the viewpoint of further reducing the amount of residual solvent, it is preferable to further dry the film-like material obtained after stretching. For example, it is preferable to further dry the film-like material obtained after the stretching while transporting it with a roll or the like.

The main drying temperature (drying temperature when not stretched) is preferably (Tg-50) to (Tg-30) ° C., where Tg is the glass transition temperature of the thermoplastic resin, and (Tg-40). ~(Tg-30)°C is more preferable. When the post-drying temperature is (Tg-50)° C. or higher, the solvent can be sufficiently volatilized and removed from the film after stretching. can be suppressed to As for the actual drying temperature, it is preferable to measure (a) the ambient temperature such as the hot air temperature, as described above.

About the process of (4) It is preferable that the obtained base film is elongate. A long base film is wound into a roll to form a roll.

The length of the long base film is not particularly limited, but can be, for example, about 100 to 10,000 m. The width of the substrate film is preferably 1 m or more, more preferably 1.3 to 4 m.

The thickness of the substrate film can be determined as appropriate, but in general, it is preferably in the range of 1 to 500 μm from the viewpoints of strength, workability such as handleability, and thinness. The thickness of the base film is more preferably in the range of 5 to 50 μm, more preferably in the range of 10 to 45 μm.

≪2 Manufacturing method≫
The method for producing an optical film of the present invention is characterized by comprising the step of forming the easy-adhesion layer on the base film, and the step of forming the hard coat layer on the easy-adhesion layer.

A method for forming each layer is not particularly limited, but a coating method is preferable. For example, it can be obtained by coating the surface of the substrate film with the composition for forming an easy-adhesion layer, drying it, then coating it with the composition for forming a hard coat layer, and irradiating it with active energy rays.

Thus, by forming the easy-adhesion layer and the hard coat layer respectively by a coating method, each layer can contain the surface conditioner and sufficiently function as the surface conditioner. In addition, by forming the easy-adhesion layer and the hard coat layer in this order on the substrate film, the surface conditioner for the easy-adhesion layer is oriented at the interface between the easy-adhesion layer and the hard coat layer, so sufficient adhesion is achieved. is obtained. Therefore, it is possible to obtain an optical film that is thin and has excellent adhesion between layers.

≪3 Polarizing plate≫
A polarizing plate of the present invention is characterized by comprising the optical film of the present invention. FIG. 2 shows an example of a preferable layer structure of the polarizing plate of the invention, but the present invention is not limited to this.

FIG. 2 is a cross-sectional view showing the basic layer structure of the polarizing plate of the present invention. The polarizing plate of the present invention preferably has the optical film of the present invention on one side of the polarizer layer 12 and the protective film 13 on the other side of the polarizer layer 12 via the adhesive layer 11 . Moreover, it may have an adhesive layer 14 in consideration of attachment to a display device.

<3.1 Polarizer layer>
The polarizing plate of the invention is obtained by further laminating a polarizer layer on the optical film of the invention. The term "polarizer" refers to an element that transmits only light with a plane of polarization in a certain direction. An example of a preferred configuration of the polarizer layer in the invention is shown below, but the invention is not limited thereto.

The type of polarizer layer is not particularly limited, and may be film type or coating type. The thickness of the polarizer layer is not particularly limited, but is preferably within the range of 0.1 to 80 μm from the viewpoint of obtaining a thin polarizing plate.

As a film-type polarizer layer, there is a resin film dyed with iodine or a dichroic dye. The resin used for the resin film may be either a hydrophobic resin or a hydrophilic resin, but is preferably a hydrophilic resin. Alcohol films are particularly preferred.

Specifically, a polyvinyl alcohol film may be uniaxially stretched and then dyed with iodine or a dichroic dye, or a polyvinyl alcohol film may be dyed with iodine or a dichroic dye and then uniaxially stretched. may Further, durability treatment may be performed with a boron compound. The thickness of the polyvinyl alcohol film used is preferably in the range of 5 to 50 μm, and the draw ratio is preferably 3 to 7 times. Among the polarizer films thus obtained, those dyed with iodine are excellent in polarizing properties, and those dyed with a dichroic dye are excellent in durability.

As the coated polarizer layer, there is a film made of a polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound and iodine or a dichroic dye. Here, the polymerizable liquid crystal compound means a liquid crystal compound having at least one polymerizable group.

Specifically, after forming a coating film of the polymerizable liquid crystal composition and removing the solvent from the coating film, the polymerizable liquid crystal compound is heated to a temperature higher than the temperature at which the phase transitions to the liquid phase, and then cooled, and the polymerization is performed. The coating-type polarizer layer can be obtained by causing a phase transition of the liquid crystal compound to a smectic phase and polymerizing the polymerizable liquid crystal compound while maintaining the smectic phase. Moreover, the coating-type polarizer layer is preferably laminated via a liquid crystal alignment layer from the viewpoint of increasing the degree of liquid crystal alignment.

The thickness of the coated polarizer layer can be appropriately selected according to the display device to which it is applied, and is preferably in the range of 0.1 to 5 μm, more preferably in the range of 0.3 to 4 μm. , 0.5 to 3 μm. If the thickness is too thin, the required light absorption may not be obtained. prone to defects. Further, when a liquid crystal alignment layer is included, the thickness of the liquid crystal alignment layer is preferably in the range of 10 to 5000 nm, more preferably in the range of 10 to 1000 nm.

<3.2 Protective film>
In order to impart strength to the polarizing plate, it is preferable that both surfaces of the polarizer layer are sandwiched between protective films, and in the present invention, one side is preferably the optical film of the present invention. Any film can be used as the protective film, and the film that is suitably used as the base film can also be suitably used as the protective film.

<3.3 Adhesive layer>
The polarizer layer and the protective film are preferably adhered via an adhesive layer, for example. The adhesive layer may be a layer obtained by drying a water-based adhesive, or a cured product layer of an active energy ray-curable adhesive. Also, the adhesive layer may contain a metallic compound filler.

The adhesive used in the adhesive layer is not particularly limited, and water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based adhesives, water-based polyurethane-based adhesives, water-based polyester-based adhesives, and the like; Specific examples of polyvinyl alcohol-based adhesives include completely saponified aqueous polyvinyl alcohol solutions (water glue). Examples of active energy ray-curable adhesives include ultraviolet-curable adhesives and electron beam-curable adhesives.

The thickness of the adhesive layer is preferably in the range of 10-75 μm, more preferably in the range of 12-50 μm.

<3.4 Adhesive layer>
Considering that the polarizing plate of the present invention is attached to the viewing side of the organic EL element, the polarizing plate of the present invention preferably has an adhesive layer.

The adhesive used in the adhesive layer is not particularly limited, and rubber-based adhesives, acrylic adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, and polyvinylpyrrolidone. system adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, and the like. Among these, it is preferable to use an acrylic pressure-sensitive adhesive from the viewpoint of excellent optical transparency, weather resistance, heat resistance, and the like. Furthermore, in the present invention, the acrylic pressure-sensitive adhesive containing a (meth)acrylic polymer as a base polymer is preferred.

The method for forming the adhesive layer is not particularly limited, and it can be formed by a method commonly used in this field. Specifically, a pressure-sensitive adhesive composition containing the pressure-sensitive adhesive or its raw material and a solvent is applied to at least one side of a substrate, and a coating film formed from the pressure-sensitive adhesive composition is dried to form it, or It can be formed by irradiating active energy rays such as ultraviolet rays. In the case of an acrylic pressure-sensitive adhesive, the pressure-sensitive adhesive composition contains monomers that form the structural units of the polymer, a polymerization initiator, and a solvent.

The pressure-sensitive adhesive composition may be directly applied to a protective film as a substrate, or may be applied to a release film, the formed pressure-sensitive adhesive layer may be transferred to the protective film, and the release film may be peeled off. The thickness of the adhesive layer is preferably in the range of 10-75 μm, more preferably in the range of 12-50 μm.

≪4 Display device≫
A display device of the present invention is characterized by comprising the optical film of the present invention. Specifically, the display device of the present invention is obtained by including the polarizing plate of the present invention. A display device is a device having a display mechanism, and includes a light-emitting element or a light-emitting device as a light source. Examples of display devices include liquid crystal displays, organic electroluminescence (EL) displays, inorganic electroluminescence (EL) displays, touch panel displays, electron emission displays (field emission displays (FED, etc.), surface field emission displays). (SED)), electronic paper (display device using electronic ink or electrophoretic element), plasma display device, projection display device (grating light valve (GLV) display device, display device having digital micromirror device (DMD) etc.) and piezoelectric ceramic displays.

The liquid crystal display device includes any of a transmissive liquid crystal display device, a transflective liquid crystal display device, a reflective liquid crystal display device, a direct view liquid crystal display device, a projection liquid crystal display device, and the like. These display devices may be display devices that display two-dimensional images, or may be stereoscopic display devices that display three-dimensional images.

The display device of the present invention is preferably a touch panel display device from the viewpoint of having a hard coat layer and having scratch resistance and impact resistance. The display device of the present invention is excellent in safety and durability by including an optical film having improved interlayer adhesion and light resistance in addition to scratch resistance and impact resistance.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these. In addition, although "parts" or "%" is used in the examples, "mass parts" or "mass%" is indicated unless otherwise specified.

<Example 1>
[Production of optical film 101]
[Preparation of base film (COP1)]
The following components are placed in a sealed container, heated and stirred to dissolve completely, and filtered with Azumi filter paper No. 1. 24 (manufactured by Azumi Filter Paper Co., Ltd.) to obtain a base film (COP) dope.

Cycloolefin resin (ARTON (registered trademark) G7810: manufactured by JSR Corporation)
95 parts by mass Dichloromethane 200 parts by mass Ethanol 10 parts by mass

The obtained dope was kept at 30°C, and the solution was uniformly cast on a stainless steel belt which was a metal support kept at 30°C. The cast dope was dried until the amount of residual solvent reached 30% by mass, and then peeled off from the stainless belt to obtain a film.
Next, the obtained film-like material was dried at 40° C. until the amount of residual solvent reached 10% by mass, and then stretched in the width direction at a draw ratio of 1.4 times (40%). Then, the obtained film-like material was further dried at 150° C. while being conveyed by a number of rolls, to obtain a base film (COP1) having a length of 3000 m and a thickness of 20 μm.

[Preparation of base film (COP2)]
A base film (COP2) was obtained in the same manner as in the preparation of the base film (COP1), except that the cycloolefin resin was changed to ZEONOR (registered trademark) manufactured by Zeon Corporation.

[Preparation of base film (TAC)]
(Preparation of dope)
A dope having the following composition was prepared. First, dichloromethane and ethanol were added to the pressurized dissolution tank. Then, the cellulose ester was put into a pressurized dissolution tank containing a solvent while being stirred, and was completely dissolved while being heated and stirred.

cellulose ester;
Triacetylcellulose 100 parts by mass Polycondensed ester compound N 2 parts by mass Polycondensed ester compound M 7 parts by mass Solvent;
Dichloromethane 540 parts by mass Ethanol 35 parts by mass Additive;
fine particles; silicon dioxide dispersion diluted solution 3 parts by mass ultraviolet absorber 2 parts by mass Furthermore, the above additive components are placed in a sealed container, dissolved with stirring, and then applied to Azumi filter paper No. 1. 244 (manufactured by Azumi Filter Paper Co., Ltd.) to prepare a dope.

The triacetyl cellulose used above is (TAC: Acetyl cellulose having a degree of acetyl substitution of 2.8, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., Mw 200,000).
Ester compound N, ester compound M, and silicon dioxide dispersion diluted solution were prepared as follows. As the ultraviolet absorber, Tinuvin 928 (trade name, manufactured by BASF Japan Co., Ltd.) was used.

(Ester compound N)
First, 251 g of 1,2-propylene glycol, 354 g of terephthalic acid, 680 g of p-toroyl acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were added to a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow cooling tube. planted in Next, a stream of nitrogen was blown into the four-necked flask, and the temperature of the solution was gradually raised while stirring until the temperature of the solution reached 230° C., and dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200° C. to obtain an ester compound N. This ester compound N had an acid value of 0.30 and a number average molecular weight of 400.

(Ester compound M)
First, 251 g of 1,2-propylene glycol, 244 g of phthalic anhydride, 103 g of adipic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were added to a 2-liter four-way flask equipped with a thermometer, a stirrer, and a slow cooling tube. Poured into a 1-necked flask. Next, a stream of nitrogen was blown into the four-necked flask, and the temperature of the solution was gradually raised while stirring until the temperature of the solution reached 230° C., thereby conducting a dehydration-condensation reaction while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200° C. to obtain a polycondensed ester compound M. This ester compound M had an acid value of 0.10 and a number average molecular weight of 450.

(Silicon dioxide dispersion)
First, 10 parts by mass of Aerosil R812 (trade name, manufactured by Nippon Aerosil Co., Ltd.) and 90 parts by mass of ethanol were stirred and mixed with a dissolver for 30 minutes, and then silicon dioxide was dispersed in ethanol using a Manton Gaulin. 88 parts by mass of methylene chloride was added to this dispersion while stirring, and the dispersion was diluted by stirring and mixing with a dissolver for 30 minutes. A silicon dioxide dispersion was obtained by filtering this diluted dispersion with a fine particle dispersion diluent filter (Advantec Toyo Co., Ltd.: polypropylene wound cartridge filter TCW-PPS-1N).

(Film formation)
The dope prepared above was uniformly cast on a stainless steel band support at a temperature of 22° C. and a width of 1.8 m using a belt casting apparatus. A stainless steel band support was used to evaporate the solvent until the residual solvent amount reached 20%, and the dope film (web) was peeled off from the stainless steel band support.

Next, the peeled web is evaporated at 35 ° C. to evaporate the solvent, slit to a width of 1.6 m, and then, using a tenter stretching machine, at a temperature of 160 ° C. in the width direction (TD direction) 1 .1 stretched. At this time, the amount of residual solvent was 4% by mass when stretching with a tenter was started.

After that, the film is dried while being transported through a drying zone of 120°C and 140°C by a large number of rollers. It was wound around a core to produce a base film (TAC). The film thickness of the base film (TAC) was 25 μm, and the winding length was 6000 m.

[Preparation of base film (acrylic)]
(Preparation of dope)
A dope having the following composition was prepared. First, dichloromethane and ethanol were added to a pressurized dissolution tank. The resin was then charged into a pressurized dissolution tank while stirring. Then, the rubber particle dispersion prepared above was added and completely dissolved while stirring. This was filtered using SHP150 (manufactured by Roki Techno Co., Ltd.) to obtain a dope.

Resin ((meth)acrylic resin) 100 parts by mass Dichloromethane 200 parts by mass Ethanol 40 parts by mass Rubber particle dispersion 200 parts by mass Tinuvin 928 (trade name, manufactured by BASF Japan Ltd.) 5 parts by mass

The (meth)acrylic resin used above is an MMA/PMI/BA copolymer ((80/10/10 mass ratio), Tg: 120° C., Mw: 2 million).

The glass transition temperature (Tg) of the acrylic resin was measured using DSC (Differential Scanning Colorimetry) according to JISK7121-2012.

The weight average molecular weight (Mw) of the acrylic resin was measured using gel permeation chromatography (HLC8220GPC manufactured by Tosoh Corporation) and a column (TSK-GELG6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL series manufactured by Tosoh Corporation). 20 mg±0.5 mg of sample was dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 mm filter. 100 mL of this solution was injected into a column (temperature of 40° C.), measured at a detector RI temperature of 40° C., and converted into styrene.

The rubber particle dispersion used above contains acrylic rubber particles M-210 (core part: multi-layered acrylic rubber-like polymer, shell part: methacrylic acid ester polymer containing methyl methacrylate as a main component, 10 parts by mass of the core-shell type rubber particles of the acrylic rubber-like polymer, Tg: about −10° C., average particle diameter: 220 nm) and 190 parts by mass of dichloromethane were stirred and mixed with a dissolver for 50 minutes, followed by milder It was obtained by dispersing at 1500 rpm using a disperser (manufactured by Taihei Kiko Co., Ltd.).

The average particle size of the rubber particles was obtained by measuring the dispersed particle size of the rubber particles in the dispersion with a zeta potential/particle size measuring system (ELSZ-2000ZS manufactured by Otsuka Electronics Co., Ltd.).

(Film formation)
A film was formed using the above dope. Specifically, using an endless belt casting apparatus, the dope was uniformly cast on a stainless steel belt support at a temperature of 30° C. and a width of 1800 mm. The temperature of the stainless steel belt was controlled at 28°C.

The solvent was evaporated on a stainless steel belt support until the amount of residual solvent in the cast dope reached 30% by mass. Then, it was peeled off from the stainless steel belt support with a peeling tension of 128 N/m to obtain a film-like material. The amount of residual solvent in the film after peeling was 30% by mass.

Next, while the peeled film was transported by a number of rollers, the obtained membranous material was stretched by 20% in the width direction (TD direction) under the condition of 140°C (Tg + 20°C) with a tenter. After that, it was further dried at 100° C. (Tg-20° C.) while being transported by rolls, slit the end portion sandwiched between the tenter clips, and wound up into a roll shape, length 3000 m, width 1.5 m, film thickness 40 μm. A base film (acrylic) (roll body) was obtained.

[Formation of Easy Adhesion Layer]
The following components were diluted with a diluent (water/methanol = 50/50 (mass%)) until the solid content concentration reached 5 mass%, and then stirred at room temperature to obtain a composition for forming an easy-adhesion layer. .

Maleic acid-modified olefin (Arrowbase (registered trademark) SB-1200: solid content concentration 25% by mass: manufactured by Unitika) 100 parts by mass Oxazoline group-containing polymer (Epocross (registered trademark) WS-700: manufactured by Nippon Shokubai Co., Ltd.)
5 parts by mass polyether-modified silicone (KF-351A: manufactured by Shin-Etsu Chemical Co., Ltd.)
1 part by mass

The obtained composition was applied to the base film prepared above with a bar coater, and dried in a drying oven at 80°C for 40 seconds to form an easily adhesive layer so that the dry film thickness was 0.4 µm. .

[Formation of hard coat layer]
The following components were diluted with a diluent (propylene glycol monomethyl ether/methyl acetate=50/50 (% by mass)) to obtain a composition for forming a hard coat layer.

Urethane acrylate (UA-1100H: manufactured by Shin-Nakamura Chemical Co., Ltd.)
100 parts by mass Photopolymerization initiator (Irgacure (registered trademark) 184: manufactured by BASF Japan)
5 parts by mass Polyether-modified silicone (BYK (registered trademark) 3450: manufactured by BYK-Chemie Japan) 1 part by mass

The obtained composition was applied to the easy-adhesion layer surface of the base film with the easy-adhesion layer prepared above with a bar coater, and dried in a drying oven at 50° C. for 40 seconds to volatilize the solvent. Then, while purging with nitrogen to create an atmosphere with an oxygen concentration of 1.0% by volume or less, an ultraviolet lamp (illuminance at the irradiation part: 100 mW/cm ² ) was used so that the irradiation amount was 0.2 J/cm ² . The optical film 101 was produced by irradiating with ultraviolet rays and curing to form a hard coat layer having a thickness of 3 μm.

[Preparation of optical films 102 to 122]
In the preparation of the optical film 101, except that the base film, the easy-adhesion layer resin, the easy-adhesion layer surface conditioner, the hard coat layer resin, and the hard coat layer surface conditioner were changed to those shown in Table I below. prepared optical films 102 to 122 in the same manner.

The products (trade names) used are shown below.
(Base film)
COP1: ARTON (registered trademark) G7810: manufactured by JSR COP2: ZEONOR (registered trademark) ZF14: manufactured by Zeon Corporation

(Resin for easy adhesion layer)
Water-based polyolefin resin A: Arrowbase (registered trademark) SB-1200: solid content concentration 25% by mass: manufactured by Unitika Water-based polyolefin resin B: Arrowbase (registered trademark) SE-1030N: solid content concentration 22% by mass: manufactured by Unitika Water-based polyolefin resin C: Arrowbase (registered trademark) SE-1010: Solid content concentration 20% by mass: Water-based polyolefin resin manufactured by Unitika Corp. Fiber-based resin: Arrowbase (registered trademark) SA-1200: Solvent-based polyolefin resin manufactured by Unitika : Surflen (registered trademark) P-1000: manufactured by Mitsubishi Chemical Corporation Acrylic resin: New Coat K-2: manufactured by Shin-Nakamura Chemical Co., Ltd.

(Surface conditioner for easy adhesion layer and hard coat layer)
Polyether-modified silicone A: KF-351A: manufactured by Shin-Etsu Chemical Co., Ltd. Polyether-modified silicone B: KF-6015: manufactured by Shin-Etsu Chemical Co., Ltd. Polyether-modified silicone C: XIAMETER (registered trademark) OFX-0193 Fluid: Dow Toray Industries, Inc. Made by polyether-modified silicone D: KF-6020: Shin-Etsu Chemical Co., Ltd. polyether-modified silicone E: KF-354L: Shin-Etsu Chemical Co., Ltd. polyether-modified silicone F: BYK (registered trademark) 3450: BYK Chemie Japan Co., Ltd. poly Ether-modified silicone G: KF-352A: manufactured by Shin-Etsu Chemical Co., Ltd. Fluorine compound: RS-75: manufactured by DIC

(Resin for hard coat layer)
Urethane acrylate A: UA-1100H: manufactured by Shin-Nakamura Chemical Co., Ltd. Tripentaerythritol acrylate: Viscoat #300: manufactured by Osaka Organic Chemical Industry Co., Ltd. Cycloolefin skeleton-containing acrylate: A-DCP: manufactured by Shin-Nakamura Chemical Co., Ltd. Polymer A: SMP- 250AP: manufactured by Kyoeisha Chemical Co., Ltd. Urethane acrylate B: Shikou (registered trademark) UV-7630B: manufactured by Mitsubishi Chemical Corporation

The HLB value was calculated by the above formula (1).

The weight average molecular weight is the weight average molecular weight measured by gel permeation chromatography (GPC) using tetrahydrofuran as described above and converted to polystyrene.

≪Evaluation≫
The optical films 101 to 122 produced were evaluated as follows. Results are shown in Table II. Moreover, in each item, 3 or more was set as the pass.

(1) Adhesion In an atmosphere of 23° C. and 55% RH, the hard coat layer of the produced optical film was subjected to a JIS-K5600-5-6 method using a cross-cut peel test jig, and a 1 mm ² 100 grids were prepared, and an adhesive tape No. 1 manufactured by Sekisui Chemical Co., Ltd. 252 was adhered thereon, pressed uniformly with a spatula, and then peeled off in the direction of 90 degrees. The tape was peeled off 10 times while exchanging the adhesive tape each time it was peeled off.
5: No peeling 4: 1 to 2 peeled grids 3: 3 to 5 peeled grids 2: 6 to 15 peeled grids 1: 16 peeled grids that's all

(2) Light resistance The prepared optical film was exposed to light for 300 hours at a wavelength of 300 to 400 nm and an irradiation intensity of 60 W using a xenon weather resistance tester (Suga Test Instruments Co., Ltd., xenon weather meter NX25). The adhesion test described in (1) was performed and evaluated.

(3) Crack Water and an organic solvent (used to disperse olefin resin in Surflen (registered trademark) P-1000) are each dropped on the surface of the base film with a dropper, and after 10 seconds, it is drawn in a circle. The liquid was wiped off by lightly rubbing. The area ratio of the whitened portion to the circled range was calculated and evaluated according to the following criteria.
5: less than 1% 4: 1-20%
3: 21-40%
2: 41-60%
1: More than 60% The results were 5 for water and 1 for organic solvents.

(4) Appearance The surface of the produced optical film was visually observed, the number of point defects (craters) per unit area (m ² ) was counted, and the average value of 10 optical film samples was calculated. evaluated according to the standard.
5: 0 pieces 4: 1 to 10 pieces 3: 11 to 20 pieces 2: 21 to 30 pieces 1: 31 pieces or more

The optical films 101 and 111 to 113 produced were evaluated as follows. Results are shown in Table II. Moreover, 3 or more was set as the pass.

(5) Humidity and Heat Resistance The produced optical film was cut into a size of 10 cm long×10 cm wide and left under the conditions of 80° C. and 90% RH for 100 hours. After that, the lifting of the edge portion of each cut sample was measured and evaluated according to the following criteria.
5: Lifting of the edge of the sample piece is less than 1 cm 4: Lifting of the edge of the sample piece is 1 cm or more and less than 3 cm 3: Lifting of the edge portion of the sample piece is 3 cm or more and less than 4 cm 2: Of the sample piece Lifting of the edge part is 4 cm or more and less than 5 cm 1: The sample piece becomes cylindrical (the curl is large and it is unsatisfactory)

Tables I and II show that the optical film of the present invention has improved interlayer adhesion and light resistance.

<Example 2>
[Preparation of optical films 201 to 212]
Regarding the easy-adhesion layer and the hard coat layer of the optical film 101 produced above, except that the thickness of each layer, the type of each surface conditioner, and the solid content ratio per unit thickness were changed as shown in Table III below. Optical films 201 to 206 were produced in the same manner. Further, optical films 207 to 212 were produced in the same manner, except that polyether-modified silicone A was used as the surface control agent for the hard coat layer. The optical films 201 to 212 produced were subjected to the above appearance evaluation. Results are shown in Table III.

From Table III, the optical film of the present invention has an Mh/Mp value in the range of 0.02 to 40 for the surface modifier contained in the easy adhesion layer and the hard coat layer. is improved.

<Example 3>
[Production of polarizing plates 301 to 306]
(Preparation of film-type polarizer layer)
A polyvinyl alcohol film with a thickness of 25 μm was swollen with water at 35°C. The resulting film was immersed in an aqueous solution of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and further immersed in an aqueous solution of 3 g of potassium iodide, 7.5 g of boric acid and 100 g of water at 45°C. . The obtained film was uniaxially stretched under conditions of a stretching temperature of 55° C. and a stretching ratio of 5 times. This uniaxially stretched film was washed with water and then dried to obtain a film-type polarizer layer with a thickness of 12 μm.

(Preparation of polarizing plate)
Polarizing plates 301 to 306 were produced by laminating the film-type polarizer layer obtained above and the protective film (optical film or substrate film obtained above) in the combination shown in Table IV. The optical film and the polarizer layer were adhered using a completely saponified polyvinyl alcohol aqueous solution (water glue).

Moreover, the terms described in Table IV are as follows.
T1: Protective film on viewing side (optical film above)
T2: Protective film on liquid crystal cell side (above base film)
PVA: film-type polarizer layer obtained above

[Manufacturing of liquid crystal display devices]
A liquid crystal display device including the polarizing plate produced above was produced. Specifically, using Apple Inc.'s iPad (registered trademark) 2 (IPS mode liquid crystal display device), the polarizing plates on both sides that had been bonded in advance were peeled off, and the prepared polarizing plates were attached to the glass of the liquid crystal cell. pasted on the surface. A liquid crystal display device was manufactured by pasting together such that the absorption axis of the produced polarizing plate was in the same direction as the absorption axis of the previously pasted polarizing plate.

≪Evaluation≫
The following evaluations were performed on the liquid crystal display devices each having the manufactured polarizing plates 301 to 306 . Results are shown in Table IV. Moreover, in each item, 3 or more was set as the pass.

(6) Light resistance After exposing the prepared liquid crystal display device to a xenon weather resistance tester (Suga Test Instruments Co., Ltd., xenon weather meter NX25) at a wavelength of 300 to 400 nm and an irradiation intensity of 60 W for 300 hours. , the liquid crystal display device was kept lit while displaying black. At this time, when observed from the front direction of the liquid crystal display device, luminance unevenness during black display was observed, and the degree of occurrence of luminance unevenness was evaluated according to the following criteria.
5: No unevenness 4: No shading of transmitted light 3: Slight shading of transmitted light 2: Clear shading at the edge of the screen Clear shading is observed in the center

(7) Humidity and Heat Resistance The obtained liquid crystal display device was left under conditions of 80° C. and 90% RH for 500 hours. After that, with the liquid crystal display device displaying black at room temperature, the presence or absence of defects (white dots) during black display on the display screen was visually confirmed and evaluated according to the following criteria.
5: 0 defects 4: 1 to 2 defects 3: 3 to 4 defects 2: 5 to 6 defects 1: 6 or more defects

From Table IV, it can be seen that the display device of the present invention has improved light resistance and moist heat resistance by using the optical film of the present invention as a protective film on the viewing side.

From the above results, it can be seen that the problems of the present invention can be solved by selecting the resin used for the easy-adhesion layer and the surface conditioner used for the easy-adhesion layer and the hard coat layer.
That is, it is possible to provide an optical film with improved interlayer adhesion and light resistance, a method for producing the same, and a polarizing plate and a display device having the same.

1 hard coat layer 2 easily adhesive layer 3 base film 10 optical film 11 adhesive layer 12 polarizer layer 13 protective film 14 adhesive layer 20 polarizing plate

Claims (7)

An optical film comprising a substrate film, an easy-adhesion layer and a hard coat layer in this order,
The easy-adhesion layer contains a water-based polyolefin resin,
The easy-adhesion layer and the hard coat layer each contain a surface modifier,
the surface conditioner contained in the easy-adhesion layer is polyether-modified silicone,
The HLB value of the polyether-modified silicone is in the range of 5 to 15,
An optical film, wherein the surface modifier contained in the hard coat layer has a weight-average molecular weight of 4,000 or less. The optical film according to claim 1, wherein the base film contains a cycloolefin resin. The optical film according to claim 1 or 2, wherein the surface conditioner contained in each of the easy-adhesion layer and the hard coat layer is the same compound. When the mass of the surface conditioner contained in the easy-adhesion layer and the hard coat layer is Mp and Mh, respectively, the content mass ratio (Mh/Mp) is in the range of 0.02 to 40. The optical film according to any one of claims 1 to 3, characterized by: An optical film manufacturing method for manufacturing the optical film according to any one of claims 1 to 4,
forming the easy-adhesion layer on the base film;
A method for producing an optical film, comprising the step of forming the hard coat layer on the easy-adhesion layer. A polarizing plate comprising the optical film according to any one of claims 1 to 4. A display device comprising the polarizing plate according to claim 6 .

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