KR20130123346A - Optical film and polarization sunglass - Google Patents

Abstract

The present invention provides an optical film which is easily manufactured; is used in a polarizing plate having a thickness; and maintains an optical function of the optical film when the optical film is laminated on other optical films. The optical film is formed by a compression molding method. The thickness of the optical film is 100 ��to 500 �� The transmittance of visible light is over 87%. The haze value is under 2%. A side direction retardation value is under 200 nm. A thickness direction retardation value is under 400 nm. When the optical film is used for polarization sunglasses, the polarization sunglasses have enough thickness without decreasing the optical function of the polarization sunglasses.

Description

[0001] OPTICAL FILM AND POLARIZATION SUNGLASS [0002]

The present invention relates to an optical film and polarized sunglasses.

It is known that polarized sunglasses can use a retardation film having a polarizer and a low retardation on both sides. As such a retardation film, for example, a triacetylcellulose film (referred to as a TAC film) is used (see Japanese Patent Laid-Open No. 2007-256544).

This triacetylcellulose film is formed by a casting method in view of reducing the retardation and suppressing birefringence. The triacetyl cellulose film formed by the casting method has a low phase difference but a small thickness, and therefore, when the triacetyl cellulose film is used in a polarizing sunglass lens, a triacetylcellulose film formed by a plurality of (for example, three) By superimposing the cellulose film on the lens, the thickness of the lens is made sufficiently large.

However, when a plurality of triacetylcellulose films are stuck to each other as described above, if the adherend surfaces are not completely adhered to each other, light may be scattered on the joint surfaces. For this reason, it is necessary to bond a plurality of triacetylcellulose films while keeping the bonding precision high, which increases the labor required for such a work, which tends to cause a decrease in productivity.

Japanese Patent Application Laid-Open No. 2007-256544

(Initiation of invention)

(Problems to be Solved by the Invention)

The present invention has been made in view of these problems, and it is an object of the present invention to provide a polarizing sunglass lens which can easily and surely be produced, has a sufficient thickness, and can be laminated on another optical film without hindering the optical function of other optical films. An optical film which can be suitably used for a polarizing plate or the like which requires the same thickness, and polarized sunglasses using the optical film.

In order to solve the above problems, the optical film of the present invention,

Formed by an extrusion molding method,

The thickness is not less than 100 μm and not more than 500 μm,

A visible light transmittance of 87% or more,

A haze value of 2% or less,

Retardation value (Ro value) of 200 nm or less and retardation value (Rth value) in the thickness direction of 400 nm or less.

The " thickness " of the optical film means an average thickness.

The visible light transmittance means the transmittance in the visible light region measured using a spectrophotometer according to JIS-R-3106.

The retardation value in the plane direction (Ro value) is a value obtained by the following equation.

Ro value = (Ny-Nx) Xd

The thickness direction retardation value (Rth value) is the value Rth obtained by the following equation.

Rth value = ((Nx + Ny) / 2-Nz) xd

Here, Nx is the refractive index of the fast axis (the axis parallel to the plane direction) of the film, and Ny is the refractive index of the film of the film, which is parallel to the plane direction and perpendicular to the fast axis Nz is the refractive index of the film in the thickness direction (direction perpendicular to the plane direction), and d is the thickness of the film.

In the case where the optical film has a thickness of 100 μm or more and 500 μm or less and is laminated on another relatively thin optical film (for example, in the case of a polarizing sunglass lens), the optical film .

Further, since the visible light transmittance of the optical film is not less than 87%, sufficient visible light can be transmitted through the base film, which makes it difficult to give a dark impression to the wearer when used as a polarizing sunglass lens. Further, since the haze value of the base film is 2% or less, it is possible to suppress deterioration of the sharpness of the image formed by the rays transmitted through the base film, thereby giving a blurred impression to the wearer when used in a polarizing sunglass lens Do not. Thus, when the optical film is used as a lens for polarized sunglasses, a lens having good visibility can be obtained.

Further, in the optical film, the retardation value in the plane direction is not more than 200 nm and the retardation value in the thickness direction is not more than 400 nm. Therefore, the optical film does not inhibit the optical function of the optical film other than the film laminated on other optical films, The optical function of the polarizing film is not deteriorated even when the polarizing film is laminated on the polarizing film as a lens of polarizing sunglasses.

In addition, since the optical film is formed by the extrusion molding method, it can be made into a film having a sufficient thickness while having the above-described optical function, and the production thereof can be easily and reliably performed, thereby improving the productivity .

Further, the optical film may use polycarbonate as the main polymer. As a result, the retardation value can be controlled easily and reliably, and the optical film can be easily and reliably produced.

The optical film may be a cycloolefin copolymer as the main polymer. Thus, even when the sheet using the optical film is formed into a three-dimensional curved shape, the control of the retardation value is easy and reliable. That is, when the optical film is formed into a three-dimensional curved shape as described above, heat and pressure are applied to the optical film by heat molding or the like. In the optical film using the cycloolefin copolymer as the main polymer, The retardation value can be easily maintained, and therefore, the retardation value can be controlled easily and surely. Therefore, for example, when the film is used for the lens of the polarizing sunglass, it is possible to adopt a configuration in which the lens has a three-dimensional curved shape, and as a result, the optical performance is not deteriorated .

The optical film may use an acrylic resin as the main polymer. As a result, the optical film has high transparency and a visible light transmittance at a high level can be exhibited.

Further, the optical film is preferably used for a lens of polarized sunglasses. As a result, the thickness of the polarizing sunglass can be made sufficiently by the optical film, and the optical function such as the polarization characteristic of the polarizing sunglasses is not impaired.

The polarizing sunglasses according to the present invention performed to solve the above-described problems include a lens including the optical film having the above-described structure.

Since the polarizing sunglass has a sufficient thickness of the optical film, the thickness of the polarizing sunglass lens can be made sufficient. The optical film has a visible light transmittance of 87% or more, a haze value of 2% or less, a retardation value in the plane direction of 200 nm or less, and a retardation value in the thickness direction of 400 nm or less. And does not deteriorate the optical function.

INDUSTRIAL APPLICABILITY As described above, the optical film of the present invention can be easily and securely produced by extrusion molding, and has a sufficient thickness. Thus, when the optical film is used in combination with another optical film, It is possible to obtain an effect that it is difficult to inhibit the optical function of the optical film other than the optical film.

Further, the polarizing sunglasses of the present invention can be easily and reliably produced by extrusion molding as described above, and thus, compared to the conventional method in which a plurality of triacetylcellulose films are adhered to each other, The thickness of the lens can be made sufficient because the optical film has a sufficient thickness and the optical function such as the polarization characteristic of the polarizer is not easily inhibited even if the optical film is laminated The effect can be obtained.

1 is a schematic perspective view showing a polarized sunglass according to an embodiment of the present invention;
2 is a schematic cross-sectional view of a sheet for a polarizing lens used in a lens of polarizing sunglasses of Fig. 1;
3 is a schematic sectional view of a sheet for a polarizing lens used in a lens of polarizing sunglasses according to another embodiment of the present invention.

(Mode for carrying out the invention)

1, a lens 3 of a polarizing sunglass 1 having a frame 2 and a pair of lenses 3 attached to the frame 2 will be described below with reference to Fig. (Base film) 20 (optical film) used in the present invention.

The base film 20 is formed into a sheet shape by extrusion molding. Specifically, it is formed by melting a film material in a molding machine, extruding the molten film material from a T die, and cooling the extruded film material in a sheet form. Here, the molding conditions such as the extrusion conditions and the resin temperature in the molding machine are set according to the optical characteristics of the film material and the base film 20 described later.

Further, the thickness (average thickness) of the base film 20 is made to be not less than 100 μm and not more than 500 μm, preferably not less than 200 μm and not more than 300 μm. If the thickness is less than the above lower limit value, the base film 20 becomes relatively thin, and the lens 3 can not have a sufficient thickness. On the other hand, when the upper limit value is exceeded, it becomes difficult to obtain a desired optical characteristic, which will be described later.

The base film 20 may have a visible light transmittance of at least 87%, preferably at least 88%, more preferably at least 89%, and even more preferably at least 90%. When the visible light transmittance of the polarizing sunglasses 1 is less than or equal to the upper limit value, sufficient visible light can be transmitted through the base film 20, so that it is difficult to give a dark impression to the wearer when used in the lens 3 of the polarizing sunglass 1.

Further, the haze value of the base film 20 is made 2% or less, preferably 1% or less. By setting the haze value to be equal to or lower than the upper limit value, it is possible to suppress deterioration of the sharpness of the image formed by the light beam transmitted through the base film 20, and when the lens 3 is used for the polarizing sunglass 1, It is possible to make the lens 3 having good visibility without giving a faint impression.

The base film 20 is made to have a retardation value in the plane direction of 200 nm or less, preferably 150 nm or less, more preferably 50 nm or less, further preferably 20 nm or less. Further, the base film 20 is made to have a retardation value in the thickness direction of 400 nm or less, preferably 100 nm or less, more preferably 80 nm or less. Thereby, when used in the lens 3 of the polarizing sunglass 1, the polarization characteristics of the polarizing sunglasses 1 are not hindered.

Here, the retardation value Ro in the plane direction is a value obtained by the following equation.

Ro = (Ny-Nx) xd

The retardation value in the thickness direction (Rth) is a value obtained by the following formula.

Here, Nx is the refractive index of the fast axis (axis parallel to the plane direction) of the base film 20, Ny is the refractive index of the slow axis (plane parallel to the plane direction) of the base film 20, Nz is the refractive index of the base film 20 in the thickness direction of the base film 20 (direction perpendicular to the plane direction), d is the thickness of the base film 20 Respectively.

The base film 20 preferably has a glass transition temperature (Tg) of 100 占 폚 or more and 170 占 폚 or less, more preferably 105 占 폚 or more and 160 占 폚 or less, still more preferably 110 占 폚 or more and 150 占 폚 or less . By setting the glass transition temperature within such a range, it is possible to perform the molding easily and reliably in the case of thermoforming the base film 20 (and the sheet using the same), and the retardation value is maintained at the time of thermoforming easy.

As the main polymer of the substrate film 20, polycarbonate, cycloolefin copolymer, acrylic resin and the like can be used. In addition, various additives such as an ultraviolet absorber and a UV stabilizer can be added to the substrate film 20, depending on the purpose.

Here, by using polycarbonate as the main polymer, it is advantageous that the retardation value can be controlled easily and reliably.

Further, by using the cycloolefin copolymer as the main polymer, when the lens 3 of the polarizing sunglass 1 has a three-dimensional curved shape (see Fig. 1), the base film 20 exhibits birefringence Can be prevented. That is, when the base film 20 is formed into a three-dimensional curved shape, heat and pressure are applied to the base film 20 by, for example, thermoforming. However, in the base film 20 using the cycloolefin copolymer as the main polymer , The change in retardation based on heat or pressure is small, and therefore, the retardation value can be easily maintained.

Further, by using an acrylic resin as the main polymer, the transparency is high and a visible light transmittance at a high level can be exhibited.

Next, a polarizing lens sheet comprising the base film 20 and the polarizing film 30 laminated on the base film 20 will be described with reference to FIG.

In the polarizing lens sheet of Fig. 2, the base film 20 is laminated on both sides of the polarizing film 30. Fig. The base film 20 and the polarizing film 30 are fixed to each other by various methods, for example, by means of an adhesive or the like. When an adhesive is used, it is preferable to use a transparent adhesive.

The polarizing film 30 is a sheet-like member made to transmit only a light beam in a vibration direction in a certain direction of vibration in a certain direction. As the polarizing film 30, various polarizing films 30 can be employed. For example, a polarizing film 30 in which iodinated molecules are adsorbed and oriented mainly on polyvinyl alcohol can be used. Here, the polarizing film 30 having a thickness of 50 mu m or more and 200 mu m or less can be suitably used.

Further, the structure in which the base film 20 is laminated on the polarizing film 30 is not limited to the above, and various types can be adopted. For example, the structure as shown in Fig. 3 may be adopted Do. In the polarizing lens sheet 10 of Fig. 3, the base film 20 is laminated on one side of the polarizing film 30 of a multilayer structure. The fixing method of the two films 20 and 30 is the same as described above.

The polarizing film 30 shown in Fig. 3 has a polyvinyl alcohol layer 32 (polarizing layer) in which iodinated molecules are adsorbed and oriented, and a triacetylcellulose film layer 31 and 33. The base film 20 is laminated and bonded to the outer surface of one of the triacetylcellulose film layers 33. [

As described above, a pair of lenses 3 are formed by using the polarizing lens sheet 10 having the base film 20 and the polarizing film 30, and the pair of lenses 3 are fixed to the frame 2, whereby the polarizing sunglasses 1 are obtained. When it is desired to form a three-dimensional curved surface on the lens 3, the lens 3 of the desired shape can be formed by thermoforming the polarizing lens sheet 10 before attaching to the frame 2. [

Since the base film 20 can be used as described above from the above-described constitution, it has the following advantages. That is, since the thickness of the lens 3 is not less than 100 탆 and not more than 500 탆, when the lens 3 is used for the polarizing sunglass 1, the lens 3 can have an accurate thickness by the base film 20.

Further, since the substrate film 20 has a visible light transmittance of 87% or more, a haze value of 2% or less, a retardation value in the plane direction of 200 nm or less, and a retardation value in the thickness direction of 400 nm or less, The optical function of the polarizer of the polarizing sunglasses does not deteriorate.

Further, since the optical film is formed by the extrusion molding method, as described above, a sufficient thickness can be obtained, and the optical film can be easily and reliably produced. That is, as compared with the case where the conventional triacetylcellulose film is laminated in multiple layers, the production thereof is easy and sure. In addition, the base film 20 may use polycarbonate, cycloolefin copolymer, or acrylic resin as the main polymer. By these materials, the substrate sheet having the above-described constitution can be easily and reliably produced.

Although the above-described embodiment has the above-described configuration and shows the above advantages, the present invention is not limited thereto, and can be appropriately designed and modified within the scope of the present invention.

In other words, although the lens sheet of the embodiment described above is made up of the optical film and the polarizing film as the base film, other structures can be employed. For example, another layer between the optical film (base film) and the polarizing film may be appropriately designed and modified. Specifically, it is also possible to sequentially laminate a polarizing film, an ultraviolet ray blocking layer such as an ultraviolet absorbing layer, and the optical film from the viewer side. In addition, it is possible to suitably change the design of the optical film and / or the polarizing film by providing another layer such as a protective layer or an ultraviolet ray prevention layer on the outer surface of the optical film and / or the polarizing film.

As described above, the optical film of the present invention has a high visible light transmittance, a low haze value, a retardation value in the plane direction and a retardation value in the thickness direction, and therefore, even if laminated on another optical film, For example, it can be suitably used for a lens of polarized sunglasses.

1 polarized sunglasses 2 frames
3 Lens 10 Sheet for polarized lenses
20 base film 30 polarizing film
31 triacetylcellulose film layer 32 polyvinyl alcohol layer
33 triacetylcellulose film layer

Claims (3)

Formed by an extrusion molding method,
The thickness is not less than 200 탆 and not more than 500 탆,
A visible light transmittance of 87% or more,
A haze value of 2% or less,
The retardation value in the plane direction (Ro value) is 200 nm or less,
The thickness direction retardation value (Rth value) is 400 nm or less,
A polycarbonate is used as a main polymer, the base film for polarizing lenses characterized by the above-mentioned. The base film for polarizing lenses of Claim 1 used for the lens of polarized sunglasses. A polarizing sunglasses comprising a lens comprising the polarizing lens base film according to claim 1.

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