KR20120116356A - Optical film and polarization sunglass - Google Patents

Abstract

PURPOSE: An optical film and polarizing sunglasses are provided to secure a laminating object having sufficient thickness by adjoining another optical film. CONSTITUTION: An optical film(20) is formed through extrusion molding. The thickness of the optical film is from 100 Mm to 500 Mm. The visible ray transmissivity of the optical film is more than 87%. A haze value of the optical film is less than 2%. A surface-direction retardation value of the optical film is less than 200nm. A thickness-direction retardation value of the optical film is less than 400nm.

Description

Optical film and polarized sunglasses {OPTICAL FILM AND POLARIZATION SUNGLASS}

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

It is well-known that a polarizing sunglasses can use the low retardation film which puts a polarizer and low retardation on both surfaces. As such a low retardation film, a triacetyl cellulose film (called a TAC film) is used, for example (see Unexamined-Japanese-Patent No. 2007-256544).

This triacetyl cellulose film is formed by the cast system from a viewpoint of reducing retardation and suppressing birefringence. Thus, the triacetyl cellulose film formed by the cast method has a low phase difference but becomes thinner. Therefore, when the triacetyl cellulose film is used for a lens of polarized sunglasses, a large number of triacetyl cellulose films (for example, three) are used. Ensuring sufficient thickness of a lens is carried out by laminating a cellulose film.

However, when a plurality of triacetyl cellulose films are bonded as described above, problems may occur such that light is scattered at the bonding surface unless the bonding surface is completely in contact with each other. For this reason, it is necessary to bond a large number of triacetyl cellulose films while maintaining the bonding accuracy high, but the labor required for such operation increases, and it becomes easy to become a cause of the fall of 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 can be produced easily and reliably, and having sufficient thickness and lamination to other optical films does not impair the optical function of other optical films. It is a subject to provide the optical film which can be used suitably for the polarizing plate etc. which need thickness, and the polarizing sunglasses using this.

The optical film of the present invention performed to solve the above problems,

Formed by extrusion molding,

Thickness is 100 micrometers or more and 500 micrometers or less,

Visible light transmittance is over 87%,

Haze value is 2% or less,

It is an optical film whose surface direction retardation value (Ro value) is 200 nm or less, and thickness direction retardation value (Rth value) is 400 nm or less.

In addition, "thickness" of the said optical film means an average thickness.

In addition, visible light transmittance means the transmittance of the visible light region measured using the spectrophotometer according to JIS-R-3106.

In addition, surface direction retardation value (Ro value) is a numerical value calculated by the following formula.

Ro value = (Ny-Nx) Xd

In addition, thickness direction retardation value (Rth value) is numerical value Rth calculated | required by following Formula.

Rth value = ((Nx + Ny) / 2-Nz) × d

Here, Nx is the refractive index of the fast axis (axis parallel to the plane direction) of the film, and Ny is the refractive index of the ground axis of the film (an axis parallel to the plane direction and perpendicular to the fast axis). It is refractive index, Nz is the refractive index of the film in the thickness direction (direction perpendicular | vertical to a surface direction), and d has shown the thickness of the film, respectively.

In the said optical film, when the thickness is 100 micrometers or more and 500 micrometers or less, when it is laminated | stacked and used for another comparatively thin optical film (for example, when used for the lens of polarized sunglasses), it will be made to have an exact thickness with the said optical film. Can be.

Moreover, in the said optical film, since visible light transmittance is 87% or more, it can transmit sufficient visible light to the said base film, and for this reason, it is difficult to give a dark impression to a wearer when using it as a lens of polarized sunglasses. Moreover, since the haze value of a base film is 2% or less, the fall of the sharpness of the image shape | molded by the light ray which permeate | transmits the said base film can be suppressed, and for this reason, when used for the lens of polarized sunglasses, it does not give a wearer impression to a wearer. Do not. Thereby, when this optical film is used as a lens of polarized sunglasses, it can be set as the lens with favorable visibility.

Moreover, in the said optical film, since the surface direction retardation value is 200 nm or less, and the thickness direction retardation value is 400 nm or less, even if it laminate | stacks on another optical film etc., the optical function of another optical film other than being impaired, for example, Even when laminated | stacked and used for the polarizing film as a lens of polarized sunglasses, it does not reduce the optical function of this polarizing film.

Moreover, since the said optical film is formed by the extrusion molding method, it can be set as the film which has sufficient thickness while having the optical function mentioned above, and can manufacture easily and reliably, and improves productivity. .

Moreover, the said optical film can use polycarbonate as a main polymer. Thereby, control of retardation value can be performed easily and surely, and the said optical film can be manufactured easily and reliably.

In addition, the optical film can use a cycloolefin copolymer as a main polymer. Thereby, even when the sheet using the said optical film is formed in the shape which bent in three dimensions, control of retardation value is easy and reliable, for example. That is, when formed in the shape curved in three dimensions as mentioned above, heat and pressure are added to the said optical film by thermoforming etc., but in the said optical film which uses a cycloolefin copolymer as a main polymer, Since the change in the underlying phase difference is small, it is easy to maintain the retardation value, which makes it easy and reliable to control the retardation value. For this reason, when the said film is used for the lens of polarized sunglasses, for example, the structure which a lens has a three-dimensional curved shape can be employ | adopted, and for this reason, it is excellent in design and does not impair an optical function. Has an advantage.

Moreover, an acrylic resin can be used for the said optical film as a main polymer. Thereby, transparency of the said optical film is high, and the visible light transmittance at a high level can be exhibited.

Moreover, it is preferable that the said optical film is used for the lens of polarized sunglasses. Thereby, while the thickness of the lens of a polarized sunglasses can be made sufficient by the said optical film, optical functions, such as the polarization characteristic of a polarized sunglasses, are not impaired.

Moreover, the polarizing sunglasses of this invention performed in order to solve the said subject is equipped with the lens containing the said optical film which consists of the said structure.

Since the said optical film has sufficient thickness, the said polarizing sunglasses can make thickness of the lens of a polarizing sunglasses sufficient. The optical film has a visible light transmittance of 87% or more, a haze value of 2% or less, a surface direction retardation value of 200 nm or less, and a thickness direction retardation value of 400 nm or less. Does not degrade optical function

As described above, the optical film of the present invention can be easily and reliably manufactured by extrusion molding, and has a sufficient thickness, so that when it is used by bonding to another optical film, a laminate having a sufficient thickness can be obtained and further Even if laminated | stacked on an optical film, the effect that it is difficult to inhibit the optical function of other optical films can be acquired.

Moreover, since the said optical film can be manufactured easily and reliably by extrusion molding as mentioned above, the polarizing sunglasses of this invention are compared with the past manufacture of many sheets of triacetyl cellulose films as compared with the past of a lens, Formation can be easily and surely performed, and since the optical film has a sufficient thickness, the thickness of the lens can be made sufficient, and even when the optical film is laminated, it is difficult to impair optical functions such as polarization characteristics of the polarizer. You can get the effect.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic perspective view which shows the polarizing sunglasses which concerns on one Embodiment of this invention.
FIG. 2 is a schematic cross-sectional view of a sheet for polarizing lenses used in the lens of the polarizing sunglasses of FIG. 1. FIG.
3 is a schematic cross-sectional view of a sheet for polarizing lenses used for a lens of polarized sunglasses according to another embodiment of the present invention.

(Mode for carrying out the invention)

Hereinafter, with reference to the embodiment of the present invention, as shown in FIG. 1, the lens 3 of the polarized sunglasses 1 having the frame 2 and a pair of lenses 3 attached to the frame 2. The base film 20 (optical film) used for) is described as an example.

The base film 20 is formed into a sheet by extrusion molding. Specifically, the film material is melted in the molding machine, the melted film material is extruded from the T die, and the extruded film material is cooled to form a sheet. Here, molding conditions, such as extrusion conditions and resin temperature in a molding machine, are set according to the optical characteristic of the film material or the base film 20 mentioned later.

Moreover, the thickness (average thickness) of the base film 20 is made into 100 micrometers or more and 500 micrometers or less, Preferably it is made into 200 micrometers or more and 300 micrometers or less. If it is less than the said lower limit, the base film 20 will become comparatively thin and it will become impossible to have sufficient thickness as the lens 3. On the other hand, when the said upper limit is exceeded, it will become difficult to acquire desired optical characteristic mentioned later.

In addition, the base film 20 is made to have a visible light transmittance of 87% or more, preferably 88% or more, more preferably 89% or more, still more preferably 90% or more. 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.

In addition, the haze value of the base film 20 is made into 2% or less, Preferably it is made into 1% or less. By setting it as the haze value below the said upper limit, the fall of the sharpness of the image shape | molded by the light ray which permeate | transmits the said base film 20 can be suppressed, and when used for the lens 3 of the polarized sunglasses 1 to a wearer The lens 3 with good visibility can be provided without giving a cloudy impression.

Moreover, the base film 20 is made so that surface direction retardation value may be 200 nm or less, Preferably it is 150 nm or less, More preferably, it is 50 nm or less, More preferably, it is made so that it is 20 nm or less. Moreover, the base film 20 is made so that thickness direction retardation value may be 400 nm or less, Preferably it is 100 nm or less, More preferably, it is 80 nm or less. Thereby, when used for the lens 3 of the polarized sunglasses 1, the polarization characteristic of the polarized sunglasses 1 is not impaired.

Here, surface direction retardation value Ro is a numerical value calculated by the following formula.

Ro = (Ny-Nx) × d

In addition, the thickness direction retardation value Rth is a numerical value calculated by the following formula.

Rth = ((Nx + Ny) / 2-Nz) × d Here, Nx is a refractive index of a fast axis (axis parallel to the plane direction) of the base film 20, and Ny is a slow axis (plane) of the base film 20 Is the refractive index of the axis parallel to the direction and perpendicular to the fast axis, Nz is the refractive index of the base film 20 in the thickness direction (direction perpendicular to the plane direction) of the base film 20, and d is the thickness of the film. Are respectively shown.

In addition, the base film 20 is preferably made such that the glass transition temperature (Tg) is 100 ° C or higher and 170 ° C or lower, more preferably 105 ° C or higher and 160 ° C or lower, and more preferably 110 ° C or higher and 150 ° C or lower. It is desirable to make it as possible. By setting it as the range of such glass transition temperature, when carrying out thermoforming of the base film 20 (and the sheet | seat using this), shaping | molding can be performed easily and reliably, and the said retardation value is maintained at the time of thermoforming. easy.

As the main polymer of the base film 20, polycarbonate, cycloolefin copolymer, acrylic resin, or the like can be used. Moreover, the said base film 20 can add various additives, such as a ultraviolet absorber and an ultraviolet stabilizer, according to the objective.

Here, the use of polycarbonate as the main polymer has the advantage that the retardation value can be controlled easily and reliably.

In addition, by using a cycloolefin copolymer as the main polymer, when the lens 3 of the polarized sunglasses 1 has a curved shape in three dimensions (see FIG. 1), the base film 20 exhibits birefringence. Can be prevented. That is, in the case of forming in a three-dimensionally curved shape, heat and pressure are added to the base film 20 by, for example, thermoforming, but in the base film 20 having the cycloolefin copolymer as the main polymer, The change in phase difference based on heat and pressure is small, and therefore, the retardation value is easily maintained.

Moreover, by using acrylic resin as a main polymer, transparency is high and a high level of visible light transmittance can be exhibited.

Next, the sheet for polarizing lenses which consists of the base film 20 which consists of the said structure, and the polarizing film 30 laminated | stacked on this base film 20 is demonstrated, referring FIG.

In this polarizing lens sheet of FIG. 2, the base film 20 is laminated on both surfaces of the polarizing film 30. In addition, the base film 20 and the polarizing film 30 are fixed by various methods, for example, lamination | stacking and fixing via an adhesive agent etc., for example. In addition, when using an adhesive agent, it is preferable to use a transparent adhesive agent.

This polarizing film 30 is a sheet-like member made to transmit only light in the vibration direction in the constant direction of vibration in the constant direction. Although the various polarizing film 30 can be employ | adopted as this polarizing film 30, the thing which carried out the adsorption orientation of the iodine compound molecule mainly using polyvinyl alcohol can be used, for example. Here, the polarizing film 30 can use suitably those whose thickness is 50 micrometers or more and 200 micrometers or less.

In addition, the structure which laminated | stacked the said base film 20 on the polarizing film 30 is not limited to the above thing, Various forms can be employ | adopted, for example, the structure like FIG. 3 can also be employ | adopted. Do. The base film 20 is laminated | stacked on the single side | surface of the polarizing film 30 of a multilayer structure in the polarizing lens sheet 10 of FIG. In addition, the fixing method of both films 20 and 30 is the same as that of the above description.

The polarizing film 30 shown in this FIG. 3 has the polyvinyl alcohol layer 32 (polarization layer) which adsorbed and oriented the iodine compound molecule | numerator, and the triacetyl cellulose film layer made on both surfaces of this polyvinyl alcohol layer 32 ( 31 and 33), and the base film 20 is laminated and fixed on the outer surface of one triacetylcellulose film layer 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 is formed of a frame ( By attaching to 2), the polarized sunglasses 1 is obtained. In addition, when it is desired to form a three-dimensional curved surface shape in the lens 3, the lens 3 of a desired shape can be formed by thermoforming the polarizing lens sheet 10 before attaching it to the frame 2.

Since the base film 20 can be used as mentioned above from the said structure, it has the following advantages. That is, since thickness is 100 micrometers or more and 500 micrometers or less, when used for the lens 3 of the polarized sunglasses 1, the said base film 20 can make the lens 3 correct thickness.

Moreover, since the said base film 20 has a visible light transmittance of 87% or more, a haze value of 2% or less, a planar retardation value of 200 nm or less, and a thickness direction retardation value of 400 nm or less, it is a lens of polarized sunglasses. Even if used as, it does not lower the optical function of the polarizer of polarized sunglasses.

Moreover, since the said optical film is formed by the extrusion molding method, as above-mentioned, it can have sufficient thickness and it can manufacture easily and surely. That is, compared with laminating | stacking a conventional triacetyl cellulose film in multilayer, its manufacture is easy and reliable. In addition, the base film 20 can use polycarbonate, a cycloolefin copolymer, or an acrylic resin as a main polymer. By these materials, the said base sheet which consists of the said structure can be manufactured easily and reliably.

In addition, although the said embodiment had said structure and showed said advantage, this invention is not limited to this, A design change is possible suitably within the intended range of this invention.

That is, although what was comprised with the said optical film which is a base film, and a polarizing film as the sheet | seat for lenses of the said embodiment was demonstrated, it is also possible to employ | adopt another structure. For example, design change can also be performed suitably to provide another layer between the said optical film (base film) and a polarizing film. Specifically, it is also possible to sequentially laminate an ultraviolet-ray prevention layer, such as a polarizing film, an ultraviolet absorbing layer, and the said optical film from the viewer side. In addition, it is also possible to appropriately change the design of other layers such as a protective layer or an ultraviolet ray prevention layer on the outer surface of the optical film or the polarizing film.

As described above, the optical film of the present invention has a high visible light transmittance, and has a small haze value, a plane direction retardation value, and a thickness direction retardation value. Therefore, even if laminated on another optical film, a sufficient thickness can be achieved without impairing optical characteristics. It can be provided and can be used suitably for the lens of polarized sunglasses, for example.

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

Claims (6)

Formed by extrusion molding,
Thickness is 100 micrometers or more and 500 micrometers or less,
Visible light transmittance is over 87%,
Haze value is 2% or less,
The plane retardation value (Ro value) is 200 nm or less,
Thickness direction retardation value (Rth value) is 400 nm or less, The optical film characterized by the above-mentioned. The optical film according to claim 1, wherein polycarbonate is used as the main polymer. The optical film according to claim 1, wherein a cycloolefin copolymer is used as the main polymer. The optical film according to claim 1, wherein an acrylic resin is used as the main polymer. The optical film according to claim 1, which is used for a lens of polarized sunglasses. A polarizing sunglasses comprising the lens comprising the optical film according to claim 1.

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