Film, polarizing sheet, and thermally bent molding

Abstract

To provide a film which is a thin film, has low light transmittance at a wavelength of 400 nm or less, has high light transmittance at a wavelength of 420 nm or more, and hardly causes roll contamination in manufacture, and a polarizing sheet, and a thermally bent molding.SOLUTION: A film contains 0.3 to 2.9 pts.mass of an ultraviolet absorber having a triazine structure with respect to 100 pts.mass of a bisphenol A type polycarbonate resin, wherein thickness of the film is 200 to 600 μm, average light transmittance at a wavelength of 250 to 400 nm of the film is 3% or less, and light transmittance at a wavelength of 420 nm of the film is 30% or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a film, a polarizing sheet, and a heat-bent molded article, and in particular to a film containing a polycarbonate resin as a main component. [Background technology]

[0002] Polycarbonate resin is produced by condensation polymerization of aromatic diols such as bisphenol A and carbonate precursors such as phosgene. It has excellent impact strength, numerical stability, heat resistance and transparency, and is used in a wide range of fields such as exterior materials for electrical and electronic products, automotive parts, building materials and optical parts.

[0003] On the other hand, optical lenses used in sunglasses and the like are required to have a transmittance that does not affect the field of vision while not causing glare from external light sources. In addition, it is necessary to protect the eyes from harmful light rays of specific wavelengths such as ultraviolet rays. Therefore, various technologies have been developed to use polycarbonate resin, which has excellent optical properties in addition to mechanical properties, for optical lenses for outdoor activities such as sunglasses (Patent Document 1, Patent Document 2, etc.). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-202542 A [Patent Document 2] International Publication No. 2019 / 066493 Summary of the Invention [Problem to be solved by the invention]

[0005] Up until now, there have been studies on blending ultraviolet absorbing agents into polycarbonate resins used in sunglasses lenses. However, if sunglasses are to have a vision correction function, the thickness of the lens varies depending on the eyeglasses' power. Therefore, it is required to incorporate an ultraviolet absorbing agent into a layer other than the lens. Here, sunglasses or eyeglasses have a layer structure as shown in FIG. 1, for example, and specifically, have a lens 1 and a polarizing film 2, and usually, polarizing film substrates 3 and 4 are provided on both sides of the polarizing film 2. Here, if an ultraviolet absorbing agent is not incorporated into the lens 1, it is possible to incorporate an ultraviolet absorbing agent into the polarizing film substrate 3 or polarizing film substrate 4. However, the polarizing film substrate needs to be thin, about 200 to 600 μm thick, and needs to block light with a wavelength of 400 nm or less and transmit light with a wavelength of 420 nm or more. Furthermore, the inventors have conducted research and found that when an ultraviolet absorbing agent is blended into a thin film with a thickness of about 200 to 600 μm, the ultraviolet absorbing agent volatilizes, which may cause stains on the rolls used to form the film. The present invention aims to solve these problems, and to provide a thin film that has low light transmittance for wavelengths of 400 nm or less and high light transmittance for wavelengths of 420 nm or more, and is less susceptible to roll contamination during production, as well as a polarizing sheet and a heat-bent molded body. [Means for solving the problem]

[0006] In light of the above problems, the present inventors have conducted research and found that the above problems can be solved by adjusting the light transmittance by using a specified ultraviolet absorber in a specified ratio. Specifically, the above problems were solved by the following means. <1> For 100 parts by mass of bisphenol A polycarbonate resin, A film containing 0.3 to 2.9 parts by mass of an ultraviolet absorber having a triazine structure, The thickness of the film is 200 to 600 μm, The film has an average light transmittance of 3% or less at a wavelength of 250 to 400 nm; The film has a light transmittance of 30% or more at a wavelength of 420 nm. film. <2> The ultraviolet absorber comprises a compound represented by formula (UV-1), <1> The film according to claim 1. [ka] (In formula (UV-1), R 1 is a hydrocarbon group having 1 to 10 carbon atoms, or a group consisting of a combination of a hydrocarbon group having 1 to 10 carbon atoms and -O- and / or -C(=O)-, R 2 ~R 4 each independently represents a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms, or a group consisting of a combination of a hydrocarbon group having 1 to 10 carbon atoms and -O- and / or -C(=O)-, n2 is an integer from 0 to 3, n3 and n4 each independently represent an integer of 0 to 4. <3> The n3 and n4 each independently represent an integer of 1 to 4. <2> The film according to claim 1. <4> The ultraviolet absorber comprises a compound represented by formula (UV-2): <1> The film according to claim 1. [ka] (In formula (UV-2), R 11 and R 31 , R 41 each independently represents an aliphatic hydrocarbon group having 3 to 10 carbon atoms, R 2 , R 32 , and R 42 each independently represents a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms, or a group consisting of a combination of a hydrocarbon group having 1 to 10 carbon atoms and -O- and / or -C(=O)-, n2, n3-1, and n4-1 each independently represent an integer of 0 to 3. <5> The ultraviolet absorber comprises a compound represented by formula (UV-3): <1> The film according to claim 1. [ka] (In formula (UV-3), R 11 and R 31 , R 41 are each independently an aliphatic hydrocarbon group having 3 to 10 carbon atoms.) <6> The film has a light transmittance of 3% or less at a wavelength of 400 nm. <1> ~ <5> 13. The film according to claim 12, <7> The difference between the light transmittance of the film at a wavelength of 420 nm and the light transmittance of the film at a wavelength of 400 nm is 35% or more. <1> ~ <6> 13. The film according to claim 12, <8> <1> ~ <7> 13. A polarizing sheet comprising the film according to any one of claims 1 to 12 and a polarizing film. <9> <8> A heat-bent molded product of the polarizing sheet according to claim 1. Effect of the Invention

[0007] The present invention makes it possible to provide a thin film that has low light transmittance for wavelengths of 400 nm or less and high light transmittance for wavelengths of 420 nm or more, and that is less susceptible to roll contamination during production, as well as a polarizing sheet and a heat-bent molded product. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a schematic diagram for explaining an example of a layer structure of the hot-bent molded body of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail. Note that the present embodiment is an example for explaining the present invention, and the present invention is not limited to the present embodiment. In this specification, the use of "to" means that the numerical values ​​before and after it are included as the lower limit and upper limit. In this specification, various physical properties and characteristic values ​​are those at 23° C. unless otherwise specified.

[0010] In this specification, weight average molecular weights are measured by gel permeation chromatography, unless otherwise specified. Specifically, the gel permeation chromatography apparatus used was an LC-20AD system (manufactured by Shimadzu Corporation), and an LF-804 (manufactured by Shodex Corporation) was connected to the column. The column temperature was set to 40°C. The detector used was an RID-10A (manufactured by Shimadzu Corporation) RI detector. Chloroform was used as the eluent, and a calibration curve was created using standard polystyrene (manufactured by Tosoh Corporation).

[0011] In this specification, unless otherwise specified, the glass transition temperature (Tg) is a value measured by differential scanning calorimetry (DSC) in accordance with ISO 11357. Two cycles of temperature increase and decrease are performed according to the conditions of differential scanning calorimetry (DSC measurement), and the glass transition temperature during the second temperature increase cycle is measured. The intersection of the straight line extending the low-temperature baseline to the high-temperature side and the tangent to the inflection point is the glass transition temperature and Tg. Measurement start temperature: 30°C, heating rate: 10°C / min, final temperature: 250°C, cooling rate: 20°C / min. Units are °C. As a measuring device, a differential scanning calorimeter (DSC, manufactured by Hitachi High-Tech Science Corporation, "DSC7020") can be used.

[0012] The terms "film" and "sheet" as used herein refer to generally flat molded bodies that are thin relative to their length and width. The terms "film" and "sheet" as used herein may be single-layer or multi-layer. If the measurement methods, etc. described in the standards shown in this specification vary from year to year, they will be based on the standards as of January 1, 2023, unless otherwise stated. Figure 1 may not be to scale and may not correspond to reality.

[0013] The film of the present embodiment is a film containing 0.3 to 2.9 parts by mass of an ultraviolet absorber having a triazine structure per 100 parts by mass of bisphenol A type polycarbonate resin, and is characterized in that the thickness of the film is 200 to 600 μm, the average light transmittance of the film at wavelengths of 250 to 400 nm is 3% or less, and the light transmittance of the film at a wavelength of 420 nm is 30% or more. With this configuration, it is possible to provide a thin film that has low light transmittance at wavelengths of 400 nm or less and high light transmittance at wavelengths of 420 nm or more, and is less likely to cause roll contamination during production. Furthermore, the light transmittance at a wavelength of 400 nm can be effectively reduced and the light transmittance at a wavelength of 420 nm can be effectively increased. In other words, the change in light transmittance between wavelengths of 400 and 420 nm can be increased. In this embodiment, by using an ultraviolet absorber having a triazine structure (hereinafter, sometimes referred to as a "triazine-based ultraviolet absorber") as the ultraviolet absorber, even if the thickness of the film is thin, the average light transmittance at a wavelength of 250 to 400 nm can be 3% or less, and the light transmittance at a wavelength of 420 nm of the film can be 30% or more. Furthermore, the change in light transmittance between wavelengths of 400 to 420 nm can be increased. In addition, the use of a triazine-based UV absorber makes it difficult for the UV absorber to volatilize, and roll contamination during film production can be effectively suppressed. This is presumably because the triazine-based UV absorber has high compatibility with polycarbonate resins. The details of this embodiment will be described below.

[0014] <Bisphenol A polycarbonate resin> The resin composition of this embodiment contains a bisphenol A polycarbonate resin. The bisphenol A polycarbonate resin of this embodiment is a resin in which 80% by mass or more of the structural units constituting the polycarbonate resin are structural units represented by formula (A). The proportion of the structural units represented by formula (A) in the polycarbonate resin used in this embodiment is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 99% by mass or more. The proportion of the structural units represented by formula (A) in the bisphenol A polycarbonate resin used in this embodiment may be 100% by mass excluding the terminal groups. Formula (A) [ka] In the above formula (A), n is an arbitrary number.

[0015] In the present embodiment, examples of diol components other than bisphenol A constituting the bisphenol A type polycarbonate resin include bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfoxide, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)ketone, 1,1-bis(4-hydroxyphenyl)ethane, bisphenol A, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(4-hydroxy-3-methylphenyl)ethane, bisphenol A, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(4-hydroxy-3-methylphenyl)ethane, bisphenol A, 2,2-bis(4-hydroxyphenyl)butane, 2,2 ...cyclohexane, 2,2-bis(4-hydroxy-3-methylphenyl)cyclohexane, 2,2-bis(4 Examples include 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2-bis(4-hydroxy-3-chlorophenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, and a,ω-bis[3-(ο-hydroxyphenyl)propyl]polydimethylsiloxane.

[0016] The molecular weight of the bisphenol A polycarbonate resin in this embodiment is not particularly limited, but is preferably 20,000 or more, more preferably 30,000 or more, in terms of weight average molecular weight. The weight average molecular weight is preferably 100,000 or less, more preferably 70,000 or less. By setting the weight average molecular weight to the lower limit or more, the strength of the obtained multilayer body for hot bending processing can be increased. Furthermore, by setting the weight average molecular weight to the above upper limit or less, molding processability tends to be improved. In this embodiment, two or more bisphenol A type polycarbonate resins in this embodiment having different weight average molecular weights may be mixed and used, in which case the weight average molecular weight is the weight average molecular weight of the mixture.

[0017] The glass transition temperature (Tg) of the bisphenol A type polycarbonate resin in this embodiment used in this embodiment is preferably 160° C. or lower, more preferably 155° C. or lower, even more preferably 154° C. or lower, even more preferably 153° C. or lower, even more preferably 152° C. or lower, and even more preferably 151° C. or lower. The glass transition temperature (Tg) of the bisphenol A type polycarbonate resin in this embodiment used in this embodiment is, for example, 140° C. or higher, and may be 143° C. or higher, 145° C. or higher, 147° C. or higher, or 148° C. or higher. When the resin composition in this embodiment contains two or more types of bisphenol A type polycarbonate resins, the glass transition temperature of the bisphenol A type polycarbonate resin is the sum of the values ​​obtained by multiplying the glass transition temperature of each bisphenol A type polycarbonate resin by the mass fraction.

[0018] For details of the bisphenol A type polycarbonate resin, reference can be made to the descriptions in paragraphs 0011 to 0020 of JP 2012-144604 A and paragraphs 0014 to 0035 of JP 2019-002023 A, as long as they do not deviate from the spirit of this embodiment, and the contents of these are incorporated into this specification.

[0019] The content of the bisphenol A polycarbonate resin in the film of this embodiment is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 97% by mass or more, and even more preferably 98% by mass or more, based on 100% by mass of the film. The content of the bisphenol A polycarbonate resin in the film of this embodiment is preferably such that all components other than the triazine ultraviolet absorber are bisphenol A polycarbonate resin based on 100% by mass of the film. When the film of the present embodiment contains two or more types of bisphenol A type polycarbonate resins, the total amount is preferably within the above range.

[0020] <Triazine-based UV absorbers> The film of the present embodiment contains 0.3 to 2.9 parts by mass of an ultraviolet absorber having a triazine structure (triazine-based ultraviolet absorber) per 100 parts by mass of bisphenol A-type polycarbonate resin. With this configuration, even if the thickness of the film is thin, the average light transmittance at wavelengths of 250 to 400 nm can be low and the light transmittance at a wavelength of 420 nm of the film can be high. Furthermore, the change in light transmittance between wavelengths of 400 to 420 nm can be increased. In addition, roll contamination during film production can be effectively suppressed.

[0021] The triazine-based ultraviolet absorber used in the present embodiment is not particularly limited in terms of type, etc., as long as it is an ultraviolet absorber containing a triazine structure, but it preferably contains a compound represented by formula (UV-1), more preferably contains a compound represented by formula (UV-2), and even more preferably contains a compound represented by formula (UV-3). [ka] (In formula (UV-1), R 1 is a hydrocarbon group having 1 to 10 carbon atoms or a group consisting of a combination of a hydrocarbon group having 1 to 10 carbon atoms and -O- and / or -C(=O)-, R 2 ~R 4 are each independently a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms, or a group consisting of a combination of a hydrocarbon group having 1 to 10 carbon atoms and -O- and / or -C(=O)-, n2 is an integer of 0 to 3, and n3 and n4 are each independently an integer of 0 to 4.

[0022] R 1 is a hydrocarbon group having 1 to 10 carbon atoms or a group consisting of a combination of a hydrocarbon group having 1 to 10 carbon atoms and -O- and / or -C(=O)-, is more preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms or a group consisting of a combination of an aliphatic hydrocarbon group having 1 to 10 carbon atoms and -O- and / or -C(=O)-, is even more preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms, is still more preferably a straight-chain aliphatic hydrocarbon group having 3 to 10 carbon atoms, and is even more preferably a straight-chain alkyl group having 3 to 10 carbon atoms. R 1 The number of carbon atoms in the hydrocarbon group (preferably an aliphatic hydrocarbon group, more preferably an alkyl group) as the alkyl group is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and still more preferably 5 or more, and is preferably 9 or less, more preferably 8 or less, and even more preferably 7 or less.

[0023] R 2 ~R 4 are each independently a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms, or a group consisting of a combination of a hydrocarbon group having 1 to 10 carbon atoms and -O- and / or -C(=O)-, R 2 ~R 4 At least one of R is a hydroxyl group. 2 ~R4 At least one of the others is preferably a hydrocarbon group having 1 to 10 carbon atoms, or a group formed by a combination of a hydrocarbon group having 1 to 10 carbon atoms and -O- and / or -C(=O)-. R 2 ~R 4 The hydrocarbon group having 1 to 10 carbon atoms as the alkyl group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and is preferably a straight-chain aliphatic hydrocarbon group (preferably a straight-chain alkyl group) or a phenyl group. R 2 ~R 4 The number of carbon atoms in the hydrocarbon group having 1 to 10 carbon atoms as the alkyl group is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and still more preferably 5 or more, and is preferably 9 or less, more preferably 8 or less, and even more preferably 7 or less.

[0024] n2 is an integer of 0 to 3, preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 1. n3 and n4 are each independently an integer of 0 to 4, preferably an integer of 1 or greater, more preferably an integer of 2 or greater, even more preferably an integer of 3 or greater, and preferably an integer of 4 or less.

[0025] [ka] (In formula (UV-2), R 11 and R 31 , R 41 are each independently an aliphatic hydrocarbon group having 3 to 10 carbon atoms; R 2 , R 32 , and R 42 are each independently a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms, or a group consisting of a combination of a hydrocarbon group having 1 to 10 carbon atoms and -O- and / or -C(=O)-, and n2, n3-1, and n4-1 are each independently an integer of 0 to 3.

[0026] R 11 , R 31 and R 41 are each independently an aliphatic hydrocarbon group having 3 to 10 carbon atoms, the number of carbon atoms of which is preferably 4 or more, even more preferably 5 or more, and is preferably 9 or less, more preferably 8 or less, and even more preferably 7 or less. The aliphatic hydrocarbon group is preferably a straight-chain aliphatic hydrocarbon group, and more preferably a straight-chain alkyl group. The aliphatic hydrocarbon group is preferably a straight-chain aliphatic hydrocarbon group, more preferably a straight-chain alkyl group, preferably a propyl group, a butyl group, a pentyl group, or a hexyl group, more preferably a butyl group, a pentyl group, or a hexyl group.

[0027] R 2 , R 32 , and R 42 are each independently a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms, or a group consisting of a combination of a hydrocarbon group having 1 to 10 carbon atoms and -O- and / or -C(=O)-. R 2 The preferred range of R in formula (UV-1) is 2 is the same as: R 32 , and R 42 The preferred ranges of each of the above are preferably a hydroxyl group and an alkyl group having 1 to 3 carbon atoms, and more preferably a hydroxyl group and a methyl group. n2 is an integer of 0 to 3, preferably 1 or 2, and more preferably 1. n3-1 and n4-1 each independently represent an integer of 0 to 3, preferably 1 or 2, and more preferably 2.

[0028] [ka] (In formula (UV-3), R 11 and R 31 , R 41are each independently an aliphatic hydrocarbon group having 3 to 10 carbon atoms.)

[0029] R 11 and R 31 , R 41 are each independently an aliphatic hydrocarbon group having 3 to 10 carbon atoms, the number of carbon atoms of which is preferably 4 or more, even more preferably 5 or more, and is preferably 9 or less, more preferably 8 or less, and even more preferably 7 or less. The aliphatic hydrocarbon group is preferably a straight-chain aliphatic hydrocarbon group, and more preferably a straight-chain alkyl group. The aliphatic hydrocarbon group is preferably a straight-chain aliphatic hydrocarbon group, more preferably a straight-chain alkyl group, preferably a propyl group, a butyl group, a pentyl group, or a hexyl group, more preferably a butyl group, a pentyl group, or a hexyl group.

[0030] Examples of triazine-based ultraviolet absorbents that can be used in the present embodiment are given below. It goes without saying that the ultraviolet absorbents that can be used in the present embodiment are not limited to these. [ka]

[0031] The molecular weight of the triazine-based ultraviolet absorber used in this embodiment is preferably 400 or more, more preferably 500 or more, even more preferably 550 or more, even more preferably 610 or more, and even more preferably 650 or more. By making the molecular weight of the triazine-based ultraviolet absorber equal to or more than the lower limit, the triazine-based ultraviolet absorber is less likely to volatilize, and roll staining can be more effectively suppressed. In addition, the molecular weight of the triazine-based ultraviolet absorber used in this embodiment is preferably 1000 or less, more preferably 900 or less, and even more preferably 800 or less. By making the molecular weight of the triazine-based ultraviolet absorber equal to or less than the upper limit, compatibility with polycarbonate resin tends to be further improved.

[0032] The content of the triazine-based ultraviolet absorber in the film of this embodiment is 0.3 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 0.6 parts by mass or more, more preferably 0.8 parts by mass or more, even more preferably 1.0 parts by mass or more, and even more preferably 1.2 parts by mass or more, relative to 100 parts by mass of the bisphenol A polycarbonate resin. By making it equal to or more than the lower limit, the light transmittance of the film at a wavelength of 400 nm tends to be reduced. In addition, the upper limit of the content of the triazine-based ultraviolet absorber is 2.9 parts by mass or less, preferably 2.7 parts by mass or less, more preferably 2.5 parts by mass or less, even more preferably 2.4 parts by mass or less, even more preferably 2.3 parts by mass or less, and even more preferably 2.2 parts by mass or less, relative to 100 parts by mass of the bisphenol A polycarbonate resin. By making it equal to or less than the upper limit, the yellowness of the film tends to be more effectively suppressed.

[0033] The content of the triazine-based ultraviolet absorber in the film of this embodiment is 0.3% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, more preferably 0.8% by mass or more, even more preferably 1.0% by mass or more, and even more preferably 1.2% by mass or more, based on 100% by mass of the film. By making it equal to or more than the lower limit, the light transmittance of the film at a wavelength of 400 nm tends to be reduced. In addition, the upper limit of the content of the triazine-based ultraviolet absorber is 2.9% by mass or less, preferably 2.7% by mass or less, more preferably 2.5% by mass or less, even more preferably 2.4% by mass or less, even more preferably 2.3% by mass or less, and even more preferably 2.2% by mass or less, based on 100% by mass of the film. By making it equal to or less than the upper limit, the yellowness of the film tends to be more effectively suppressed. The film of the present embodiment may contain only one type of triazine-based ultraviolet absorbent, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0034] <Other ingredients> The film of the present embodiment may or may not contain components other than the bisphenol A polycarbonate resin and the triazine-based ultraviolet absorber. Examples of other components include antioxidants, release agents, heat stabilizers, flame retardants, flame retardant assistants, colorants, antistatic agents, fluorescent brighteners, antifogging agents, flow improvers, plasticizers, dispersants, antibacterial agents, antiblocking agents, impact improvers, sliding improvers, hue improvers, and acid trapping agents. In addition, the film of this embodiment can be blended with additives described in paragraphs 0047 to 0103 of WO 2021 / 241471 without departing from the spirit of the present invention, the contents of which are incorporated herein by reference. When other components are contained, the total content thereof is preferably 0.001 to 3 mass% of the film, more preferably 2 mass% or less, even more preferably 1 mass% or less, even more preferably 0.5 mass% or less, and even more preferably 0.1 mass% or less, and may be less than 0.01 mass%. The other component may be contained in only one kind, or in two or more kinds. When two or more kinds of other components are contained, it is preferable that the total amount is in the above range.

[0035] The film of the present embodiment may be configured to be substantially free of triazine-based ultraviolet absorbers other than the compound represented by formula (UV-3). Substantially free means that the content of triazine-based ultraviolet absorbers other than the compound represented by formula (UV-3) contained in the film is less than 1 mass % of the content of the compound represented by formula (UV-3) contained in the film, and is preferably less than 0.1 mass %.

[0036] The film of the present embodiment may or may not contain an ultraviolet absorbing agent other than the triazine-based ultraviolet absorbing agent. In the first embodiment of the present invention, the film is substantially free of ultraviolet absorbers other than the triazine-based ultraviolet absorber. Substantially free means that the content of the ultraviolet absorber other than the triazine-based ultraviolet absorber is less than 1% by mass, and preferably less than 0.1% by mass, of the content of the triazine-based ultraviolet absorber contained in the film. In a second embodiment of the present invention, the film is substantially free of benzotriazole-based ultraviolet absorbers. Substantially free of benzotriazole-based ultraviolet absorbers means that the content of the benzotriazole-based ultraviolet absorbers contained in the film is less than 1% by mass, and preferably less than 0.1% by mass, of the content of the triazine-based ultraviolet absorbers contained in the film. The third embodiment of this embodiment is that the film contains both a triazine-based ultraviolet absorber and a benzotriazole-based ultraviolet absorber. In the third embodiment, the film preferably contains 1 part by mass or more of a benzotriazole-based ultraviolet absorber, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and preferably 6.5 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 8 parts by mass or less, per part by mass of the triazine-based ultraviolet absorber. In the third embodiment, only one type of benzotriazole-based ultraviolet absorber may be used, or two or more types may be used. When two or more types are used, it is preferable that the total amount is within the above range. As the benzotriazole-based ultraviolet absorber, the description in paragraphs 0023 to 0025 of JP-A-2023-025384 can be referred to, and the contents thereof are incorporated herein.

[0037] The film of this embodiment may or may not contain a visible light absorbing agent. The visible light absorbing agent is typically a colorant such as a pigment or dye. The film of the present embodiment may also be configured to be substantially free of a visible light absorbent. Specifically, the content of the visible light absorbent is preferably less than 0.01% by mass, more preferably less than 0.001% by mass, of the content of the triazine-based ultraviolet absorbent contained in the present embodiment. The film of the present embodiment may also be configured to be substantially free of black pigment (and further black colorant). Specifically, the content of the black pigment is preferably less than 0.01 mass % of the content of the triazine-based ultraviolet absorber contained in the present embodiment, and more preferably less than 0.001 mass %. The film of the present embodiment may also be configured to be substantially free of a yellow dye (or a yellow colorant). Specifically, the content of the yellow dye is preferably less than 0.01% by mass, more preferably less than 0.001% by mass, of the content of the triazine-based ultraviolet absorber contained in the present embodiment.

[0038] <Film thickness> The film of the present embodiment has a thickness of 200 to 600 μm. By setting the thickness of the film to the lower limit or more, the light transmittance of the film at a wavelength of 400 nm tends to be reduced. By setting the thickness of the film to the upper limit or less, the heat bending processability tends to be improved. The thickness of the film is preferably 250 μm or more, more preferably 280 μm or more, and is preferably 550 μm or less, more preferably 510 μm or less, even more preferably less than 500 μm, even more preferably 450 μm or less, even more preferably 400 μm or less, and even more preferably 350 μm or less.

[0039] <Film light transmittance> The film of this embodiment has an average light transmittance of 3% or less at wavelengths of 250 to 400 nm, and a light transmittance of 30% or more at a wavelength of 420 nm. The light transmittance of the film of this embodiment at a wavelength of 420 nm is preferably 35% or more, more preferably 40% or more, even more preferably 43% or more, even more preferably 45% or more, and even more preferably 47% or more. There is no particular upper limit to the light transmittance of the film of this embodiment at a wavelength of 420 nm, but 70% or less is practical. The light transmittance of the film of this embodiment at a wavelength of 400 nm is preferably 3% or less, more preferably 2% or less, even more preferably 1% or less, even more preferably 0.6% or less, even more preferably 0.1% or less, and even more preferably 0.05% or less. There is no particular lower limit for the light transmittance of the film of this embodiment at a wavelength of 400 nm, but a value of more than 0% is practical. A film satisfying the above-mentioned light transmittance can be achieved, for example, by blending a predetermined amount of a triazine-based ultraviolet absorber having a predetermined structure with a bisphenol A type polycarbonate resin. In this embodiment, the difference between the light transmittance of the film at a wavelength of 420 nm and the light transmittance of the film at a wavelength of 400 nm is preferably 35% or more, more preferably 40% or more, even more preferably 45% or more, and even more preferably 47% or more. The upper limit of the difference between the light transmittance of the film at a wavelength of 420 nm and the light transmittance of the film at a wavelength of 400 nm is not particularly set, but 80% or less is practical. Such a difference in light transmittance is mainly achieved by using a predetermined amount of a triazine-based ultraviolet absorber (preferably a compound represented by formula (UV-1), more preferably a compound represented by formula (UV-2), and even more preferably a compound represented by formula (UV-3).

[0040] The film of this embodiment preferably has a low YI (Yellow Index) value. Specifically, the YI value is preferably 20 or less, and more preferably 15 or less. The lower limit of the YI value of the film of this embodiment may be 0, but 0.01 or more is practical, and even if it is 3 or more, the required performance is sufficiently satisfied. In particular, a film having a large difference between the light transmittance at a wavelength of 420 nm and the light transmittance at a wavelength of 400 nm and having a low YI value will be more useful.

[0041] <Wound body> The film of the present embodiment can be wound around a core material to form a roll.

[0042] <Polarizing sheet> The film of the present embodiment is preferably used as a polarizing sheet. In this embodiment, the polarizing sheet is a sheet in which the film of this embodiment, the polarizing film, and the polarizing film substrate are laminated in this order. That is, the film of this embodiment is preferably used as at least one of the polarizing film substrates of the polarizing sheet. The polarizing film substrate is usually attached to the polarizing film via an adhesive. In this embodiment, one of the polarizing film substrates of the polarizing sheet may be the film of this embodiment, or may be another polarizing film substrate. The other polarizing film substrate of the polarizing sheet may be a polarizing film substrate of a known polarizing sheet, and may be the same as the film of this embodiment. The polarizing film may be a known one, and an example thereof is a polyvinyl alcohol (PVA) film in which iodine or a dichroic organic dye is adsorbed or impregnated. The adhesive for bonding the film polarizing film substrate and the polarizing film of the present embodiment can be a known adhesive, and examples of such adhesives include acrylic adhesives, urethane adhesives, epoxy adhesives, silicone adhesives, polyvinyl alcohol adhesives, etc. Among these, urethane adhesives are preferred. The thickness of the adhesive is usually 1 μm or more and usually 30 μm or less. In addition, the polarizing sheet of the present embodiment may further include a masking film or the like provided on the outer side of the polarizing film substrate.

[0043] In addition, in this embodiment, the polarizing sheet of this embodiment is preferably used for a heat-bent molded article obtained by heat bending processing, and is particularly preferably used as a polarizing film substrate for a polarizing sheet. When the film of the present embodiment is used in a polarizing sheet, it may be provided on either side of a polarizing film, or on both sides. The first mode is that the film of this embodiment is disposed so as to be located on the concave side of the polarizing film after heat bending processing, for example, on the side of the polarizing film substrate 4 in FIG. In the second embodiment, the film of this embodiment is disposed so as to be located on the convex side of the polarizing film after heat bending processing, for example, on the side of the polarizing film substrate 3 in FIG. In the third embodiment, the film of this embodiment is located on both sides of a polarizing film, for example, both of polarizing film substrates 3 and 4 in FIG. 1 are the film of this embodiment. In FIG. 1, the lens 1, the polarizing film 2, and the polarizing film substrates 3 and 4 of the polarizing sheet are bent, but it goes without saying that this embodiment also includes a case where they are not bent.

[0044] In this embodiment, the polarizing sheet is preferably used as a polarizing sheet for use in liquid crystal display devices, polarizing lenses (sunglasses lenses, ski goggles, prescription eyeglass lenses, camera viewfinder lenses), covers for various instruments, glass for automobiles, glass for trains, polarizing sheets for in-vehicle display panels and electronic device housings, etc., in-vehicle inner mirrors, silver mirrors for helmets, etc. EXAMPLES

[0045] The present invention will be described in more detail below with reference to examples. The materials, amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or the like, measurements can be made using other instruments with equivalent performance.

[0046] 1.Raw materials Bisphenol A polycarbonate sheet resin: S-3000, manufactured by Mitsubishi Gas Chemical Co., Ltd. UV absorbers B1: LA-F70, manufactured by ADEKA [ka] B2: LA-31, manufactured by ADEKA [ka]

[0047] Examples 1 to 2, Comparative Examples 1 to 6 <Film manufacturing> A polycarbonate resin film was produced by the following method. Each component listed in Table 1 was weighed out so that the amount of each component was added as listed in Table 1 (Table 1 shows the amount in parts by mass). After that, the mixture was mixed in a tumbler for 15 minutes, and then extruded into a molten state using a T-die melt extruder consisting of a vented twin-segment extruder with a barrel diameter of 25 mm and a screw L / D of 30 (manufactured by Toyo Seiki, "2D30W2") at a discharge rate of 8 kg / h and a screw rotation speed of 100 rpm. The mixture was then cooled and solidified only by the first roll of a film / sheet take-up device (manufactured by Toyo Seiki, "FT3W20") to produce a polycarbonate resin film. The cylinder / die head temperature was 280°C, and the roll temperature was 130°C. The final film thickness was adjusted to the thickness shown in Table 1 by changing the rolling speed of the first roll.

[0048] <Average light transmittance for wavelengths of 250 to 400 nm> The average light transmittance of the obtained film at a wavelength of 250 to 400 nm was measured. Specifically, the light transmittance (unit: %) of the film was measured at wavelengths of 250 to 400 nm using a spectrophotometer at a scanning speed of 300 nm / min and a sampling interval of 1 nm. The average value was calculated from the light transmittance value for each 1 nm wavelength. The measurement was carried out using a spectrophotometer U-4100 (Hitachi High-Technologies Corporation). The evaluation was made according to the following classification: A: 3% or less B: More than 3% and less than 10% C: More than 10%

[0049] <Light transmittance at 420 nm wavelength> For the obtained film, the light transmittance at a wavelength of 420 nm was measured. The measurement of the light transmittance was carried out in the same manner as the average light transmittance at the above wavelengths of 250 to 400 nm.

[0050] <Light transmittance at a wavelength of 400 nm> For the obtained film, the light transmittance at a wavelength of 400 nm was measured. The measurement of the light transmittance was carried out in the same manner as the average light transmittance at the above wavelengths of 250 to 400 nm.

[0051] <Roll stain> Regarding the roll used in the production of the film, the presence or absence of stains was visually confirmed. The confirmation of the presence or absence of stains was carried out by 5 experts and judged by a majority vote according to the following criteria. A: No roll stain was confirmed B: Roll stain was confirmed

[0052] <YI value> For the obtained film, the YI value was measured using a spectrocolorimeter under the illumination and light-receiving conditions of the post-spectral method with di: 0° in accordance with JIS Z 8722. The spectrocolorimeter used was "SD-7000" manufactured by Nippon Denshoku Industries Co., Ltd.

[0053]

Table 1

Explanation of symbols

[0054] 1 Lens 2 Polarizing film 3 Polarizing film substrate 4 Polarizing film substrate

Claims

1. For 100 parts by mass of bisphenol A polycarbonate resin, A film containing 0.3 to 2.9 parts by mass of an ultraviolet absorber having a triazine structure, The thickness of the film is 200 to 600 μm, the film has an average light transmittance of 3% or less in the wavelength range of 250 to 400 nm; The film has a light transmittance of 30% or more at a wavelength of 420 nm. film.

2. The film according to claim 1, wherein the ultraviolet absorber comprises a compound represented by formula (UV-1): 【Chemistry 1】 (In formula (UV-1), R １ is a hydrocarbon group having 1 to 10 carbon atoms, or a group formed by combining a hydrocarbon group having 1 to 10 carbon atoms with —O— and / or —C(═O)—, R ２ ~R ４ are each independently a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms, or a group formed by combining a hydrocarbon group having 1 to 10 carbon atoms with —O— and / or —C(═O)—, n2 is an integer from 0 to 3, n3 and n4 each independently represent an integer of 0 to 4.

3. 3. The film according to claim 2, wherein n3 and n4 are each independently an integer of 1 to 4.

4. The film according to claim 1, wherein the ultraviolet absorber comprises a compound represented by formula (UV-2): 【Chemistry 2】 (In formula (UV-2), R １１ and R ３１ , R ４１ are each independently an aliphatic hydrocarbon group having 3 to 10 carbon atoms, R ２ , R ３２ , and R ４２ are each independently a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms, or a group formed by combining a hydrocarbon group having 1 to 10 carbon atoms with —O— and / or —C(═O)—, n2, n3-1, and n4-1 each independently represent an integer of 0 to 3.

5. The film of claim 1, wherein the ultraviolet absorber comprises a compound represented by formula (UV-3): 【Transformation 3】 (In formula (UV-3), R １１ and R ３１ , R ４１ are each independently an aliphatic hydrocarbon group having 3 to 10 carbon atoms.

6. The film according to any one of claims 1 to 5, wherein the film has a light transmittance of 3% or less at a wavelength of 400 nm.

7. The film according to any one of claims 1 to 5, wherein the difference between the light transmittance of the film at a wavelength of 420 nm and the light transmittance of the film at a wavelength of 400 nm is 35% or more.

8. The ultraviolet absorber comprises a compound represented by formula (UV-3): The film has a light transmittance of 3% or less at a wavelength of 400 nm, 2. The film according to claim 1, wherein the difference between the light transmittance of the film at a wavelength of 420 nm and the light transmittance of the film at a wavelength of 400 nm is 35% or more. 【Chemistry 4】 (In formula (UV-3), R 11 , R 31 , and R 41 each independently represent an aliphatic hydrocarbon group having 3 to 10 carbon atoms.)

9. A polarizing sheet comprising the film according to any one of claims 1 to 5 and 8 and a polarizing film.

10. A heat-bent product of the polarizing sheet according to claim 9 .

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