JP2002267841A - Polarizing film for polarizing lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing film for a lens having excellent heat resistance and a low change rate in the optical characteristics by thermal hysteresis. SOLUTION: The polarizing film for a polarizing lens contains 100 parts by weight of a polyester resin and 0.005 to 4 parts by weight of nonwater-soluble dyes containing at least one kind of dichroic dye. The film exhibits at least 50% polarization degree and <=10% change rate in the polarization degree and in the transmittance for rays after heat-treated at 180 deg.C for 5 minutes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polarizing film for a polarizing lens. More specifically, the present invention relates to a polarizing film for a polarizing lens having excellent heat resistance and a low rate of change in optical characteristics due to heat history.

[0002]

2. Description of the Related Art A lens having a polarizing film laminated thereon is used for sunglasses, goggles and the like for anti-glare use. This polarizing lens is a laminate of a polarizing film and transparent glass or resin, and the polarizing film also has a predetermined curvature like the lens. As the polarizing film used for these, those obtained by impregnating polyvinyl alcohol with iodine and those obtained by impregnating polyvinyl alcohol with a water-soluble dichroic dye are generally used.

[0003] However, although a polarizing film in which polyvinyl alcohol is impregnated with iodine is inexpensive, iodine sublimates due to heat at the time of performing the curvature processing, the degree of polarization after the processing decreases, and the light transmittance also decreases. It changes greatly. In the case of polyvinyl alcohol impregnated with a water-soluble dichroic dye, the use of the dye has slightly improved the heat resistance, but is not sufficient. Cracks and the like are easy to enter, and handling is difficult. Also, to make up for it, after laminating triacetyl cellulose or polycarbonate on both sides of the polyvinyl alcohol-based polarizing film,
Some are subjected to curvature processing. However, the laminated sheets may be oriented by the curvature processing, and the lens may blur. In addition, when the lens is used, moisture is absorbed from the end portion into the polyvinyl alcohol, causing problems such as discoloration and delamination.

As described above, in the conventional polarizing film, since the base material is polyvinyl alcohol, the film is torn during the forming when the curvature processing is performed, the film is cracked during the processing, the processing is performed, or during the use. The optical characteristics change when the lens is processed, and the heat resistance is not sufficient, so that the optical characteristics change during the curvature processing, the molding temperature range during the lens processing is restricted, and the lens cannot be left in a vehicle or the like where the temperature becomes high when the lens is used. Problems. For this reason,
The fact is that the spread of polarized lenses in sunglasses, goggles, and the like has been slow.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a polarizing film for a lens having excellent heat resistance and a low rate of change in optical properties such as the degree of polarization and light transmittance due to heat history. Is to provide.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a polarizing film containing a specific amount of a water-insoluble dye containing at least one dichroic dye is superior to a polyester resin. The present inventors have found that they have heat resistance and moldability, and that the rate of change in optical properties such as the degree of polarization and light transmittance is small even when exposed to high temperatures.

That is, the present invention comprises 100 parts by weight of a polyester resin and 0.005 to 4 parts by weight of a water-insoluble dye containing at least one dichroic dye, and has a degree of polarization of at least 50% at 180 ° C. This is a polarizing film for a polarizing lens, in which the degree of change in the degree of polarization and light transmittance when subjected to heat treatment for 5 minutes is 10% or less.

[0008] The polarizing film for a polarizing lens according to the present invention has excellent heat resistance. Therefore, even when exposed to a high temperature, the degree of change in the degree of polarization and light transmittance is low. Therefore, even when glasses or the like made of a polarizing lens provided with the polarizing film for a polarizing lens of the present invention are left in a car or the like under the scorching sun and exposed to a high temperature, optical properties such as a degree of polarization and a light transmittance. Special envoys do not decline.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polarizing film for a polarizing lens of the present invention is formed into a resin composition by adding a specific amount of a water-insoluble dye containing at least one dichroic dye to a polyester-based resin to form a resin composition. Mold into Next, after the obtained film is stretched in a uniaxial direction, it is manufactured by performing a heat treatment at a predetermined temperature.

Examples of the polyester resin used in the present invention include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and the like. These resins are preferred because they are insoluble in water and do not melt at a temperature of 180 ° C. Considering heat resistance, moldability and the like, polyethylene terephthalate is preferred.

As the dichroic dye used in the present invention, a water-soluble direct dye is not preferred. Water-insoluble ones can be appropriately selected from disperse dyes and acid dyes. Further, those which do not cause decomposition, discoloration or the like at the melting point of the polyester resin as the base material are preferable. Examples of such dichroic dyes include dyes disclosed in Japanese Patent Publication No. 4-30986. Of these, chemical formula (1)

[0012]

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Alternatively, the chemical formula (2)

[0014]

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Compounds represented by the following are preferably exemplified.
These may be used alone or as a mixture. In consideration of the degree of polarization, light transmittance, and the like of the obtained polarizing film, the amount of the dichroic dye is preferably 0.005 to 4 parts by weight based on 100 parts by weight of the polyester resin.

In producing the polarizing film for a polarizing lens of the present invention, the above polyester resin and a water-insoluble dichroic dye are mixed to form a resin composition. The method for producing the resin composition is not particularly limited, and examples thereof include a method of mixing both using a known ribbon blender, tumbler mixer, or the like. The mixing temperature may be around room temperature. If necessary, other additives such as an ultraviolet absorber can be added.

The method for forming a resin composition containing a water-insoluble dichroic dye is not particularly limited, and any known method can be used. For example, a film is formed by a T-die extrusion method using a known single-screw extruder or a twin-screw extruder, an inflation-type extrusion method, or the like. Usually, the film forming temperature is in a range from the melting temperature of the resin to the decomposition temperature. Then
The obtained film is stretched in a uniaxial direction. The stretching method is not particularly limited, and the stretching is performed by a known method. Normal,
As stretching conditions, the film is stretched 2 to 10 times in a uniaxial direction in a range from the glass transition temperature of the resin to the melting temperature.
The stretching direction may be a machine direction or a direction orthogonal to the machine direction.

Further, a polarizing film can be obtained by performing an annealing treatment in a state of being restricted in the stretching direction. The annealing treatment may be performed at the time of the curved surface processing or after the curved surface processing. The annealing treatment method is not particularly limited, and is performed by a known method. Usually, in a temperature range from the crystallization temperature of the resin to the melting temperature but lower than 5 seconds to 30 seconds.
The annealing treatment is performed for a minute while being bound in the stretching direction.

The degree of polarization of the polarizing film for lenses of the present invention produced as described above is preferably at least 50%. When the degree of polarization is less than 50%, when used for antiglare use, the antiglare effect is undesirably reduced. Further, considering the brightness of the polarizing lens, the light transmittance of the polarizing film according to the present invention is at least 5%.
It is preferred that In addition, the thickness is 10 to 500 μm
Is preferable. If the thickness is less than 10 μm, the rigidity of the polarizing film becomes weak and it becomes difficult to handle. 500μ thick
If it exceeds m, it is difficult to obtain a curvature suitable for the lens when performing a curvature process on the polarizing film. Also, when processed as a polarizing lens, it becomes undesirably thick.

Usually, the polarizing film according to the present invention is formed as a lens after performing a curvature process. The method for performing the curvature processing is not particularly limited, and general press molding, vacuum molding, and the like are used. At the time of the curvature processing, a protective film may be laminated on one side or both sides of the polarizing film for the purpose of preventing the polarizing film from being scratched. The protective film is not particularly limited as long as it does not cause gluing when peeled from the polarizing film after the curvature processing.

When using a polarizing film which has been subjected to an annealing treatment in advance, the temperature at which the curvature processing is performed is preferably in the range of the crystallization temperature of the resin or higher and lower than the melting temperature.
When a polarizing film that has not been subjected to an annealing treatment is used, the temperature is preferably equal to or higher than the glass transition temperature of the resin and lower than the melting temperature. In the case of a polarizing film which has not been subjected to an annealing treatment and which has been subjected to curvature processing, it is preferable to perform annealing treatment after the curvature processing in order to obtain dimensional stability. Usually, the radius of curvature when performing curvature processing is 40 to 1000 mm.
It is about.

The temperature of the annealing treatment depends on the use condition of the lens,
In particular, considering that the resin is left in a vehicle, the range of 120 ° C. to the melting temperature of the resin is preferable. Also, when molding the lens,
In the case where a method of injection molding a lens after selecting a polarizing film in a mold in advance, annealing at 180 ° C. to the melting temperature of the resin is preferable.

The polarizing film according to the present invention can be subjected to various lens processings after the curvature processing. As a method of molding a plastic lens, there are generally a casting method of a thermosetting resin and an injection molding method of a thermoplastic resin. In casting of thermosetting resin, insert a polarizing film with curvature processing between two molds holding a gasket, inject the thermosetting resin, apply the required temperature, and take several hours to several tens of hours. Molding method. At this time, it is also effective to apply an adhesive to the polarizing film to be inserted in advance according to the type of the thermosetting resin. In injection molding of a thermoplastic resin, resins such as polycarbonate and polyamide are usually used. A polarizing lens can be obtained by setting a polarizing film in a mold in advance and performing injection molding. Alternatively, a polarizing lens can be obtained by a method of bonding a glass lens or a plastic lens on one side or between two lenses via an adhesive. These can be used not only for lenses but also for other anti-glare applications such as goggles and helmet shields.

[0024]

The present invention will be described in more detail with reference to the following examples. The methods for measuring the light transmittance and the degree of polarization described in the examples are as follows.

(1) Light transmittance (%) Using a spectrophotometer (model: U3500, manufactured by Hitachi, Ltd.), the visible region of 400 to 70 was measured for 10 samples.
The measurement is performed with light in a wavelength region of 0 nm, and the average value is calculated.

(2) Degree of Polarization (%) Using the same measuring device as in the preceding paragraph, the samples used in the preceding paragraph were randomly superposed two by two, and the transmission axis (stretching direction) was measured by superposing two transmission axes in parallel. The light transmittance (Tp) at the time of measurement and the light transmittance (Tc) when two sheets are superimposed orthogonally and measured are measured. The following equation (1) [Equation 1]

[0027]

(Equation 1)

Then, the degree of polarization (V) is calculated.

Example 1 To 100 parts by weight of polyethylene terephthalate, 0.8 part by weight of a dye mainly containing an anthraquinone dichroic dye represented by the above-mentioned chemical formulas (1) and (2) was added. Mixing was performed using a tumbler mixer. The obtained resin composition was extruded using a T-die single screw extruder, cooled and solidified on a mirror-finished roll, and the thickness was adjusted to 5 mm.
A 00 μm film was formed. 1
Cut into 80 mm square, uniaxially stretched using a batch type stretching tester manufactured by Iwamoto Seisakusho at a temperature of 80 ° C. so that the stretching ratio becomes 4 times, and then subjected to a heat treatment at 220 ° C. for 5 minutes under tension, A polarizing film having a thickness of 125 μm was obtained. The obtained polarizing film has a degree of polarization of 99.0%,
The light transmittance was 18.0%. Next, the heat resistance was evaluated at 180 ° C. for 5 minutes using a constant temperature oven. The degree of polarization of the polarizing film after the heat test was 99.
2% and the rate of change was + 0.2%. The light transmittance was 17.5%, and the change rate was -2.8%. The amount of change was small and good results were obtained.

Next, this polarizing film was cut into a square of 120 mm and heated at 150 ° C.
Using a mold, a curvature process was performed using a vacuum forming machine (drape method). The polarizing film subjected to the curvature processing has no cracks or the like, and has a polarization degree of 98.7% and a light transmittance of 1
9.0%, and the rate of change of the degree of polarization after the curvature processing is -0.0%.
The rate of change of the light transmittance was + 5.6%. The amount of change was small even after the curvature processing. After that, curvature radius 80mm
The polarizing film was sandwiched via the glass lens and an adhesive to obtain a polarizing lens.

Further, the gasket 2 held by casting was used.
After inserting the polarizing film after the heat resistance test between the molds, the diethylene glycol bis-allyl carbonate monomer and the dibutyl percarbonate catalyst are injected between the molds, and the temperature is gradually raised from room temperature to 110 ° C. and molded for 20 hours to form a polarizing lens. I got Furthermore, the polarizing film after the heat resistance test was inserted into a mold subjected to curvature processing, and injection molding of polycarbonate was performed to obtain a polarizing lens. These polarizing lenses were able to be molded without any particular problem in molding.

Comparative Example 1 An unstretched film of polyvinyl alcohol having a thickness of 75 μm [vinylon film, No. 7500, manufactured by Kuraray Co., Ltd.]
Was swollen with water at 42 ° C., and the swollen film was immersed in an aqueous iodine solution to impregnate iodine. The film was stretched in water at 42 ° C. so that the stretching ratio became 4 times. Further, the water on the film surface was wiped off and dried to obtain a polarizing film. The light transmittance of the obtained polarizing film is 37.0%, and the degree of polarization is 99.9%.
It was 0%. Then, the temperature was adjusted to 18 using a constant temperature oven.
It was left at 0 ° C. for 5 minutes to evaluate heat resistance.
After the heat resistance test, the polarizing film became a transparent film, and the iodine black was lost.

Comparative Example 2 Polyvinyl alcohol unstretched film having a thickness of 75 μm [Kuraray Co., Ltd., Vinylon film No. 7500]
Was swollen in water at 42 ° C., and the swollen film was immersed in an aqueous solution containing an azo dichroic dye as a main component to impregnate the dye. The film was stretched in water at 42 ° C. so that the stretching ratio became 4 times. Further, the water on the film surface was wiped off and dried to obtain a polarizing film. The light transmittance of the obtained polarizing film was 40.2%, and the degree of polarization was 92.5%. Then, it was left at a temperature of 180 ° C. for 5 minutes using a constant temperature oven to evaluate heat resistance. The obtained polarizing film had a degree of polarization of 89.0%, a transmittance of 20.0%, and a large change in transmittance.

[0034]

The polarizing film for a polarizing lens according to the present invention has excellent heat resistance. Therefore, even when exposed to a high temperature, the degree of change in the degree of polarization and light transmittance is low. Therefore,
Optical special use such as the degree of polarization and light transmittance even when glasses or the like made of a polarizing lens provided with the polarizing film for a polarizing lens of the present invention are left in a car under the hot sun and exposed to high temperatures. It does not drop.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G02C 7/12 G02C 7/12 // B29K 67:00 B29K 67:00 B29L 7:00 B29L 7:00 11 : 00 11:00 (72) Inventor Jin Koga 2-1 Tango-dori, Minami-ku, Nagoya-shi, Aichi F-term (reference) in Mitsui Chemicals, Inc. 2H049 BA02 BA26 BB44 BC03 BC24 4F071 AA43 AE09 AF29Y AF30Y AF35Y BC01 BC12 4F210 AA24 AB12 AG01 AH73 QC01 QG01 QW11 4J002 CF061 CF071 CF081 EU026 EV326 FD096 GP00

Claims (2)

[Claims] 1. A water-insoluble dye containing 100 parts by weight of a polyester resin and at least one dichroic dye.
5 to 4 parts by weight, the degree of polarization of which is at least 50%, 18
A polarizing film for a polarizing lens, wherein the degree of change in the degree of polarization and light transmittance when subjected to heat treatment at 0 ° C. for 5 minutes is 10% or less. 2. The method according to claim 1, wherein the thickness is 10 to 500 μm.
A polarizing film for a polarizing lens as described in the above.