Multilayer materials for heat bending, heat-bendable materials, sunglasses, and protective films

Abstract

To provide a multilayer body for heat bending, a heat-bent body, sunglasses, and a protective film that, when the protective film is peeled off after heat bending, leaves little residue at the edges of the thermoplastic resin film, prevents the protective film from sticking, and has excellent surface quality on the thermoplastic resin film surface. [Solution] The heat-bending multilayer according to the present disclosure is a heat-bending multilayer having a thermoplastic resin film containing a thermoplastic resin and a protective film provided on the surface of the thermoplastic resin film, wherein the protective film has a polyolefin layer containing a polyolefin with a melting point of 150°C or higher and an adhesive layer, the adhesive layer and the thermoplastic resin film are in contact, and the maximum cross-sectional height Wt of the waviness curve of the surface of the polyolefin layer used to form the protective film is 0.30 μm or less, measured in accordance with JIS B 0601:2013 and with a cutoff value of λ = 942 μm.

Description

Technical Field

[0001] The present invention relates to a multilayer body for thermoforming, a thermoformed body, sunglasses, and a protective film.

Background Art

[0002] Currently, for the polarizing sheet that has been put into practical use, typically, a polarizing film in which iodine or a dichroic organic dye is adsorbed or impregnated in polyvinyl alcohol (PVA) is used. This polarizing film is usually made into a polarizing sheet (sometimes referred to as a polarizing plate) that is easy to handle, suitable for secondary processing, inexpensive, and lightweight by using a transparent resin such as triacetyl cellulose on one or both sides of the polarizing film as a protective film for the polarizing film.

[0003] On the other hand, when a polarizing sheet is used for applications that require impact resistance, for example, for polarizing lenses for sunglasses, a polarizing film protective film (sometimes referred to as a polarizing film substrate) such as a polycarbonate film is laminated on both sides of the polarizing film using a dichroic organic dye to form a polarizing sheet. This is punched into a desired shape, thermoformed into a partial spherical surface, and appropriately surface-treated, etc., to be processed into a polarizing lens for sunglasses. The polarizing sheet for such thermoforming is known, for example, from Patent Document 1 and Patent Document 2.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When heat-bending a polarizing sheet, which is made by laminating thermoplastic resin films such as polycarbonate films on both sides of a polarizing film, it is common practice to provide protective films on both sides of the polarizing sheet. After heat-bending with these protective films in place, it is common practice to peel off the protective films before use. However, when the protective films are peeled off after heat-bending, residue may remain on the edges of the thermoplastic resin film on the heat-bent polarizing sheet, or parts of the protective films may become stuck. In addition, the unevenness of the protective film may be transferred to the thermoplastic resin film, causing a visually shimmering effect on the surface of the thermoplastic resin film. In this invention, this visual shimmering effect is referred to as surface shimmer. The present invention aims to solve the above problems and to provide a multilayer body for heat bending, a heat-bent body, sunglasses, and a protective film that, when the protective film is peeled off after heat bending, leaves no residue at the edges of the thermoplastic resin film, does not adhere to the protective film, and has excellent surface quality on the surface of the thermoplastic resin film. [Means for solving the problem]

[0006] Based on the above problems, the inventors conducted investigations and found that the above problems can be solved by using a polyolefin layer containing a polyolefin with a high melting point as the substrate for the protective film, and by setting the maximum cross-sectional height Wt of the waviness curve of the polyolefin layer to 0.30 μm or less. Specifically, the above problem was solved by the following means. [1] A multilayer body for heat bending, comprising a thermoplastic resin film containing a thermoplastic resin and a protective film provided on the surface of the thermoplastic resin film, The protective film comprises a polyolefin layer containing a polyolefin with a melting point of 150°C or higher, and an adhesive layer. The adhesive layer and the thermoplastic resin film are in contact, A multilayer body for heat bending, wherein the surface of the polyolefin layer used to form the protective film has a maximum cross-sectional height Wt of the waviness curve, measured in accordance with JIS B 0601:2013, with a cutoff value of λ = 942 μm, which is 0.30 μm or less. [2] The multilayer body for heat bending according to [1], wherein the adhesive layer comprises an acrylic adhesive and / or a urethane acrylate adhesive. [3] The multilayer body for heat bending according to [1] or [2], wherein the haze of the polyolefin layer, as measured in accordance with JIS K 7136, is 15% or less. [4] The multilayer body for heat bending according to any one of [1] to [3], wherein the polyolefin layer comprises polypropylene. [5] The thermoplastic resin film comprises at least one selected from the group consisting of polycarbonate, polyamide, poly(meth)acrylic acid ester, and polyester, the multilayer body for heat bending according to any one of [1] to [4]. [6] The heat-bending multilayer according to any one of [1] to [5], wherein the protective film side is positioned closer to the mold than the thermoplastic resin film side when the heat-bending multilayer is heat-bent using a mold. [7] A multilayer body for heat bending according to any one of [1] to [6], wherein the maximum cross-sectional height Wt of the waviness curve of the surface of the polyolefin layer used to form the protective film is 0.01 μm or more, as measured in accordance with JIS B 0601:2013 and with a cutoff value of λ = 942 μm. [8] The thickness of the polyolefin layer is 20 to 150 μm, The thickness of the adhesive layer is 1 to 20 μm. The thickness of the thermoplastic resin film is 100 to 1000 μm. A multilayer body for heat bending described in any one of [1] to [7]. [9] Furthermore, including a polarizing film, The protective film, the thermoplastic resin film, and the polarizing film are laminated in that order. A multilayer body for heat bending described in any one of [1] to [8].

[10] A multilayer body for heat bending according to any one of [1] to [9], for use in manufacturing polarizing sheets.

[11] The adhesive layer comprises an acrylic adhesive and / or a urethane acrylate adhesive, The haze of the aforementioned polyolefin layer, as measured in accordance with JIS K 7136, is 15% or less. The polyolefin layer comprises polypropylene, The thermoplastic resin film comprises at least one selected from the group consisting of polycarbonate, polyamide, poly(meth)acrylic acid ester, and polyester. The maximum cross-sectional height Wt of the waviness curve of the surface of the polyolefin layer used to form the protective film, measured in accordance with JIS B 0601:2013 and with a cutoff value of λ = 942 μm, is 0.01 μm or more. The thickness of the polyolefin layer is 20 to 150 μm. The thickness of the adhesive layer is 1 to 20 μm. The thickness of the thermoplastic resin film is 100 to 1000 μm. Furthermore, it includes a polarizing film, The protective film, the thermoplastic resin film, and the polarizing film are laminated in that order. [1] A multilayer body for heat bending as described above.

[12] The heat-bending multilayer according to any one of [1] to

[11] , wherein the protective film side is positioned closer to the mold than the thermoplastic resin film side when the heat-bending multilayer is heat-bent using a mold. A heat-bent body obtained by heat-bending a multilayer body for heat bending described in any one of

[13] [1] to

[12] . A heat-bent body obtained by heat-bending a multilayer body for heat bending described in any one of

[14] [1] to

[12] , A heat-bent body in which the surface of the thermoplastic resin film in the heat-bent body is measured in accordance with JIS B 0601:2013, and the maximum value Wt(ta) of the maximum cross-sectional height Wt of the waviness curve when a cutoff value of λ=942μm is set is 0.35μm or less, and Wt(ta) is the maximum value of Wt at each point when the circumference of the thermoplastic resin film is divided into 6 equal angles over a circumference of 5 mm inward from the outer circumference.

[15] A heat-bending workpiece of a multilayer body for heat bending, having a thermoplastic resin film containing a thermoplastic resin and a protective film provided on the surface of the thermoplastic resin film, A heat-bent body in which, when the protective film is peeled off from the heat-bent body, the maximum value Wt(ta) of the maximum cross-sectional height Wt of the waviness curve on the surface of the thermoplastic resin film is measured in accordance with JIS B 0601:2013, and a cutoff value of λ=942μm is set, and Wt(ta) is the maximum value of Wt at each point when the circumference of the thermoplastic resin film is divided into 6 equal angles over a circumference of 5 mm inward from the outer edge.

[16] Sunglasses according to any one of

[13] to

[15] , including the heat-bent body.

[17] A protective film having a polyolefin layer containing a polyolefin with a melting point of 150°C or higher, and an adhesive layer, The protective film is used by attaching the adhesive layer side to the thermoplastic resin film when a heat-bending process is performed on a multilayer body for heat bending, which includes a thermoplastic resin film containing a thermoplastic resin, to obtain a heat-bent body. A protective film in which, when the protective film is peeled off the heat-bent body, the maximum cross-sectional height Wt of the waviness curve on the surface of the polyolefin layer, measured in accordance with JIS B 0601:2013 and with a cutoff value of λ = 942 μm, is 0.30 μm or less. [Effects of the Invention]

[0007] According to the present invention, when the protective film is peeled off after thermoforming, there is little residue at the end of the thermoplastic resin film, there is no adhesion of the protective film, and a multilayer body for thermoforming, a thermoformed body, sunglasses, and a protective film excellent in the flatness of the surface of the thermoplastic resin film can be provided.

Brief Description of Drawings

[0008] [Figure 1] It is a schematic cross-sectional view showing an example of the multilayer body for thermoforming of the present embodiment. [Figure 2] It is a schematic cross-sectional view showing an application example of the multilayer body for thermoforming of the present embodiment. [Figure 3] It is a schematic diagram showing a curve of the cross-section of the polyolefin layer. [Figure 4] It is a schematic view of an example showing a process of manufacturing a polarizing sheet using the multilayer body for thermoforming of the present embodiment. [Figure 5] It is a projection observation photograph used for evaluation in the example.

Modes for Carrying Out the Invention

[0009] Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. Note that the following present embodiment is an exemplification for explaining the present invention, and the present invention is not limited to only the present embodiment. In this specification, "~" is used to mean including the numerical values described before and after it as the lower limit value and the upper limit value. Further, any combination of the upper limit value and the lower limit value of the numerical values in this specification can be cited as an example of the present embodiment. In this specification, a combination of preferred modes is a more preferred mode. In this specification, various physical property values and characteristic values are those at 23°C unless otherwise specified.

[0010] In this specification, unless otherwise specified, weight-average molecular weight and number-average molecular weight are polystyrene-converted values ​​measured by GPC (gel permeation chromatography).

[0011] In this specification, unless otherwise specified, the glass transition temperature (Tg) shall be the value measured by differential scanning calorimetry (DSC) in accordance with ISO 11357.

[0012] In this specification, multilayer bodies include those in the form of films or sheets. “Film” and “sheet” refer to molded articles that are thin in thickness relative to their length and width, and are generally flat. Furthermore, “film” and “sheet” in this specification may be single-layer or multi-layer. If the measurement methods, etc., described in the standards shown in this specification differ from year to year, unless otherwise specified, the standards as of January 1, 2025 shall apply. If the measurement methods, etc., described in the standards shown in this specification are obsolete as of January 1, 2025, the standards in effect at the time of obsolete shall apply. Figures 1-4 may not accurately reflect reality due to their scales and other factors.

[0013] The present invention provides a heat-bending multilayer comprising a thermoplastic resin film containing a thermoplastic resin and a protective film provided on the surface of the thermoplastic resin film, wherein the protective film has a polyolefin layer containing a polyolefin with a melting point of 150°C or higher and an adhesive layer, the adhesive layer and the thermoplastic resin film are in contact, and the maximum cross-sectional height Wt of the waviness curve of the surface of the polyolefin layer used to form the protective film, measured in accordance with JIS B 0601:2013 and with a cutoff value set at a wavelength λ=942μm, is 0.30μm or less. With this configuration, when the protective film is peeled off after heat bending, there is little residue at the edges of the thermoplastic resin film, the protective film does not adhere, and a heat-bending multilayer with excellent surface quality of the thermoplastic resin film is obtained.

[0014] In heat bending processes, multilayer bodies for heat bending are typically used after the protective film has been removed following the heat bending process. However, various problems can occur when the protective film is removed from the heat-bent body after heat bending. One problem is that a portion of the protective film remains as residue at the edges of the thermoplastic resin film. Another problem is that the protective film adheres to the thermoplastic resin film. Furthermore, another problem is that the irregularities of the protective film are transferred to the surface of the thermoplastic resin film, resulting in a deterioration of the surface quality. In this invention, the above problems were solved by using a polyolefin layer containing a polyolefin with a melting point of 150°C or higher, and by setting the maximum cross-sectional height Wt of the waviness curve on the surface of the polyolefin layer to 0.30 μm or less. Specifically, by using a polyolefin layer containing a polyolefin with a melting point of 150°C or higher, it was possible to make it difficult for a part of the protective film to weld to the edge of the thermoplastic resin film as residue. Furthermore, by setting the maximum cross-sectional height Wt of the waviness curve on the surface of the polyolefin layer to 0.30 μm or less, even if the irregularities of the polyolefin layer are heat-pressed onto the surface of the thermoplastic resin film during heat bending, the surface of the thermoplastic resin film does not become uneven but becomes flat, achieving a surface quality that is acceptable. In particular, it is presumed that the improvement in surface quality in this invention was completed by finding that the waviness curve with longer wavelengths has a greater influence than the roughness curve with shorter wavelengths on the surface state of the polyolefin layer. Polyolefin layers are generally hard, uneven films. In this invention, we investigated flat polyolefin films in terms of long-wavelength undulation curves and solved the above problem by using them as protective films.

[0015] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is merely one example of an embodiment of the present invention and is not limited to these.

[0016] <Layer configuration> First, the layer structure of the heat-bending multilayer of this embodiment will be described with reference to Figure 1. Figure 1 is a schematic cross-sectional view showing an example of the heat-bending multilayer of this embodiment, where 1 is the heat-bending multilayer, 2 is a thermoplastic resin film, 3 is an adhesive layer, and 4 is a polyolefin layer. The heat-bending multilayer 1 of this embodiment has a thermoplastic resin film 2 and a protective film, and the protective film has an adhesive layer 3 and a polyolefin layer 4, with the adhesive layer 3 in contact with the thermoplastic resin film 2. The protective film typically consists only of an adhesive layer 3 and a polyolefin layer 4, but may have other layers as long as it does not depart from the spirit of the present invention. Furthermore, in the drawings, the same reference numerals are used for the same components in Figure 2 and subsequent figures.

[0017] Figure 2 is a schematic cross-sectional view showing an application example of the heat-bending multilayer of this embodiment, where 1 represents the heat-bending multilayer of this embodiment, 5 represents the adhesive layer, and 6 represents the polarizing film. The heat-bending multilayer 1 illustrated in Figure 2 is bonded to a polarizing film 6 via an adhesive layer 5 on the thermoplastic resin film 2 (not shown) side. That is, the heat-bending multilayer 1 illustrated in Figure 2 further includes a polarizing film, and is laminated in the order of the protective film, the thermoplastic resin film, the adhesive layer, and the polarizing film. The polarizing film may or may not be a component of the heat-bending multilayer in this embodiment. In particular, some sunglasses do not have a polarizing film, and such heat-bending multilayers do not have a polarizing film. Returning to Figure 2, the heat-bending multilayer bodies 1·1 in this embodiment may be identical or different. Also, in Figure 2, a known heat-bending multilayer body may be provided in place of one of the heat-bending multilayer bodies 1. In the embodiment shown in Figure 2, a thermoplastic resin film 2 (not shown) acts as a protective film for the polarizing film 6. Such a multilayer body is preferably used as a heat-bending multilayer body for manufacturing polarizing sheets. The following provides details about thermoplastic resin film, protective film, polarizing film, and adhesive layer.

[0018] <Thermoplastic resin film> The thermoplastic resin film used in this embodiment includes a thermoplastic resin. In this embodiment, the surface condition (residue, adhesion, surface quality) of the thermoplastic resin film after heat bending is determined by the melting point and waviness of the polyolefin layer. Therefore, the thermoplastic resin film in this embodiment does not have any specific requirements regarding the type of resin it is composed of, as long as it can be heat-bent, and a wide range of known thermoplastic resins can be used. The thermoplastic resin preferably contains at least one selected from the group consisting of polycarbonate, polyamide, poly(meth)acrylic acid ester, and polyester, more preferably contains polycarbonate, and even more preferably contains aromatic polycarbonate. The thermoplastic resin film in this embodiment may contain polyolefin as the thermoplastic resin, but it is a layer with a lower polyolefin content than the polyolefin layer. In this embodiment, the polyolefin content in the thermoplastic resin film is preferably less than 10% by mass, more preferably less than 7% by mass, even more preferably less than 5% by mass, even more preferably less than 3% by mass, and may be less than 1% by mass.

[0019] Examples of aromatic polycarbonates in this embodiment include resins in which 80% by mass or more of the total constituent units of the polycarbonate are derived from aromatic monomers. The proportion of constituent units derived from aromatic monomers 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. Examples of the aromatic monomers include bisphenol A, bisphenol C, and bisphenol AP, with bisphenol A and / or bisphenol AP being preferred, and bisphenol A being more preferred.

[0020] An example of aromatic polycarbonate in this embodiment is a resin containing the constituent unit represented by formula (A) in a proportion of 80% by mass or more of the total constituent units of the polycarbonate. In this embodiment, the proportion of the constituent unit represented by formula (A) in the aromatic polycarbonate may be 100% by mass, excluding the end groups. Formula (A) [ka] In equation (A) above, n is any number.

[0021] In this embodiment, the diol components constituting the aromatic polycarbonate include 4,4'-isopropylidenediphenol, as well as 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, and 2,2-bis(4-hydroxyphenyl) Examples include 3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)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.

[0022] In this embodiment, the molecular weight of the aromatic polycarbonate is not specifically defined, but it is preferably 20,000 or more, and more preferably 30,000 or more, in terms of weight-average molecular weight. Furthermore, the weight-average molecular weight is preferably 100,000 or less, and more preferably 70,000 or less. By setting the weight-average molecular weight above the lower limit, the strength of the resulting multilayer material for heat bending can be increased. Conversely, by setting the weight-average molecular weight below the upper limit, the moldability tends to improve. In this embodiment, two or more aromatic polycarbonates with different weight-average molecular weights may be mixed and used. In this case, the molecular weight of the aromatic polycarbonates shall be the weight-average molecular weight of the mixture.

[0023] In this embodiment, the glass transition temperature (Tg) of the aromatic polycarbonate 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. Furthermore, the glass transition temperature (Tg) of the aromatic polycarbonate in this embodiment may be, for example, 140°C or higher, and may also be 143°C or higher, 145°C or higher, 147°C or higher, or 148°C or higher. In this embodiment, if the thermoplastic resin film contains two or more aromatic polycarbonates, the glass transition temperature of the aromatic polycarbonates is the sum of the values ​​obtained by multiplying the glass transition temperature of each aromatic polycarbonate by its mass fraction.

[0024] Further details regarding aromatic polycarbonates can be found in paragraphs 0011-0020 of Japanese Patent Application Publication No. 2012-144604 and paragraphs 0014-0035 of Japanese Patent Application Publication No. 2019-002023, without departing from the spirit of this embodiment, and these contents are incorporated herein.

[0025] In this embodiment, the content of thermoplastic resin in the thermoplastic resin film is preferably 80% 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 may be 99% by mass or more. The thermoplastic resin film may contain only one type of thermoplastic resin, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0026] The thermoplastic resin film in this embodiment may or may not contain other components besides the thermoplastic resin. Other components include antioxidants, mold release agents, heat stabilizers, flame retardants, flame retardant enhancers, ultraviolet absorbers, near-infrared absorbers, colorants, antistatic agents, fluorescent whitening agents, anti-fogging agents, flow improvers, plasticizers, dispersants, antibacterial agents, antiblocking agents, impact improvers, sliding improvers, hue improvers, acid trapping agents, and the like. Furthermore, the thermoplastic resin film may be formulated with additives described in paragraphs 0047 to 0103 of International Publication No. 2021 / 241471, without departing from the spirit of the present invention, and this is incorporated herein. If the thermoplastic resin film contains other components, their total content is preferably 0.001 to 3% by mass, more preferably 2% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and may be less than 0.01% by mass. The thermoplastic resin film may contain only one other component or two or more other components. When it contains two or more other components, it is preferable that the total amount is within the above range.

[0027] In this embodiment, the thickness of the thermoplastic resin film is preferably 100 μm or more, more preferably 200 μm or more, and even more preferably 250 μm or more. Setting the thickness of the thermoplastic resin film to be above the lower limit tends to ensure the rigidity of the multilayer material for heat bending, such as a polarizing sheet. Furthermore, the thickness of the thermoplastic resin film is preferably 1000 μm or less, more preferably 800 μm or less, and even more preferably 600 μm or less. Setting the thickness of the thermoplastic resin film to be below the upper limit tends to improve heat bending processability.

[0028] <Protective film> The multilayer body for heat bending in this embodiment has a protective film provided on the surface of the thermoplastic resin film described above. The protective film has a polyolefin layer and an adhesive layer. The polyolefin layer and the adhesive layer may each consist of only one layer or two or more layers, and are usually five layers or less. The polyolefin layer is preferably one to three layers thick. The details of the polyolefin layer and adhesive layer are described below.

[0029] <<Polyolefin layer>> The polyolefin layer in this embodiment contains a polyolefin with a melting point of 150°C or higher. The inclusion of polyolefin tends to improve the conformability of the molded product during heat bending, and by setting the melting point of the polyolefin to 150°C or higher, the occurrence of suction cup marks on the protective film during the process of being carried by being adsorbed onto suction cups during heat bending tends to be further suppressed.

[0030] The polyolefin contained in the polyolefin layer is not specified in any particular way, but it preferably contains at least one of polyethylene, polypropylene, poly(ethylene / propylene), poly(4-methyl / 1-pentene), and poly-1-butene, more preferably contains polyethylene, polypropylene, and at least one of poly(ethylene / propylene), and even more preferably contains polypropylene. Furthermore, polyethylene, polypropylene, etc., also include those in which a portion of them (for example, 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less) is modified with other olefins or other monomers.

[0031] The melting point of the polyolefin used in this embodiment is 150°C or higher, preferably 155°C or higher, more preferably 157°C or higher, practically 180°C or lower, preferably 167°C or lower, and more preferably 164°C or lower. Setting the melting point of the polyolefin to be above the lower limit reduces the amount of residue left at the edges of the thermoplastic resin film, and also tends to reduce suction cup marks during transport. Furthermore, setting the melting point of the polyolefin to be below the upper limit tends to reduce wrinkles on the concave side.

[0032] Furthermore, the melting point of the polyolefin used in this embodiment is preferably higher than the glass transition temperature of the thermoplastic resin contained in the thermoplastic resin film, and more preferably 5°C or more (preferably 50°C or less) higher than the glass transition temperature of the thermoplastic resin contained in the thermoplastic resin film. Furthermore, the melting point of the polyolefin used in this embodiment is preferably 5°C or more (preferably 10°C or more, and preferably 50°C or less) higher than the heat bending temperature. The melting point of the polyolefin is measured according to the method described in the examples below.

[0033] The polyolefin content in the polyolefin layer of this embodiment is preferably 80% 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 may be 99% by mass or more. The polyolefin layer may contain only one type of polyolefin, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0034] The polyolefin layer in this embodiment may or may not contain other components besides polyolefin. Other components include antioxidants, mold release agents, heat stabilizers, flame retardants, flame retardant enhancers, ultraviolet absorbers, near-infrared absorbers, colorants, antistatic agents, fluorescent whitening agents, anti-fogging agents, flow improvers, plasticizers, dispersants, antibacterial agents, antiblocking agents, impact improvers, sliding improvers, hue improvers, acid trapping agents, and the like. Furthermore, the polyolefin layer may be formulated with additives described in paragraphs 0047 to 0103 of International Publication No. 2021 / 241471, without departing from the spirit of the present invention, and this is incorporated herein. If the polyolefin layer contains other components, their total content is preferably 0.001 to 3% by mass of the polyolefin layer, more preferably 2% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and may be less than 0.01% by mass. The polyolefin layer may contain only one other component or two or more other components. When it contains two or more other components, it is preferable that the total amount is within the above range.

[0035] In this embodiment, the polyolefin layer used to form the protective film is measured in accordance with JIS B 0601:2013, and the maximum cross-sectional height Wt of the waviness curve when a cutoff value is set at a wavelength λ = 942 μm is 0.30 μm or less. A polyolefin layer is typically a film with an uneven surface. Figure 3 is a schematic diagram showing the cross-sectional curve of a polyolefin layer, where 41 represents the cross-sectional curve of the polyolefin layer. The cross-sectional curve 41 of the polyolefin layer can be divided into a waviness curve 42 and a roughness curve 43 by dividing it at specific wavelengths. In this invention, it has been found that if the waviness curve 42 is large, the unevenness is transferred to the thermoplastic resin film after heat bending, resulting in a lower surface quality for the resulting heat-bent product. In this embodiment, with respect to the cross-sectional curve of the polyolefin layer, when the cutoff value is set at a wavelength λ = 942 μm, it is preferable that the maximum cross-sectional height Wt of the waviness curve of the polyolefin layer is 0.27 μm or less, more preferably 0.25 μm or less, and even more preferably 0.21 μm or less. Furthermore, while the lower limit of the maximum cross-sectional height Wt of the waviness curve of the polyolefin layer is ideally 0 μm, it is practical to be 0.01 μm or more. In other words, for commonly used polyolefin films, the maximum cross-sectional height Wt of the waviness curve is generally greater than 0.30 μm, and it is considerably difficult to make it less than 0.01 μm. The maximum cross-sectional height Wt of the waviness curve of the polyolefin layer is measured according to the method described in the examples below. Furthermore, the maximum cross-sectional height Wt of the waviness curve of the polyolefin layer only needs to be satisfied by the polyolefin layer before the protective film is formed (for example, a commercially available polyolefin film). However, if the polyolefin layer before the protective film is formed satisfies the desired maximum cross-sectional height Wt of the waviness curve, it is considered that the polyolefin layer after heat bending will also satisfy the desired maximum cross-sectional height Wt of the waviness curve. Also, if the polyolefin layer after heat bending satisfies the desired maximum cross-sectional height Wt of the waviness curve, it is considered that the polyolefin layer before the protective film is formed will also satisfy the desired maximum cross-sectional height Wt of the waviness curve.

[0036] In this embodiment, the haze of the polyolefin layer, as measured in accordance with JIS K 7136, is preferably 15% or less, more preferably 12% or less, and even more preferably 10% or less. The lower limit of the haze of the polyolefin layer is ideally 0%, but even if it is 1% or more, it sufficiently satisfies the required performance. The haze of the polyolefin layer may be before protective film formation, after protective film formation, or after heat bending, and it is preferable that any of the above haze values ​​satisfy the above values, and it is more preferable that at least the polyolefin layer before protective film formation satisfies the above values.

[0037] In this embodiment, the thickness of the polyolefin layer is preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 35 μm or more. By setting the thickness of the polyolefin layer to be above the lower limit, the occurrence of suction cup marks on the protective film tends to be further suppressed. Furthermore, the thickness of the polyolefin layer is preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 110 μm or less. By setting the thickness of the polyolefin layer to be below the upper limit, the conformability to the molded product during heat bending tends to be further improved. When the polyolefin layer consists of multiple layers, it is preferable that the total thickness falls within the above range.

[0038] <<Adhesive layer>> The adhesive layer in this embodiment is a layer for temporarily bonding the polyolefin layer and the thermoplastic resin film. The adhesive layer in this embodiment does not specify its details, as long as it achieves this purpose; a known adhesive layer can be used. In this embodiment, it is preferable that the adhesive strength of the adhesive layer with the polyolefin layer is greater than the adhesive strength with the thermoplastic resin film. In particular, it is preferable that the adhesive strength with the polyolefin layer is greater than the adhesive strength with the thermoplastic resin film after heat bending. Examples of adhesive layers in this embodiment include acrylic adhesives, urethane adhesives, epoxy adhesives, silicone adhesives, and polyvinyl alcohol adhesives. Among these, it is preferable to include an acrylic adhesive and / or a urethane acrylate adhesive, and more preferably a urethane acrylate adhesive. Details of the acrylic adhesive can be found in paragraphs 0034-0042 of International Publication No. 2024 / 177041, which are incorporated herein by reference. Examples of urethane-based adhesives include Oripain adhesive manufactured by Toyo Chem Co., Ltd. and UK-05FL adhesive manufactured by Henkel Co., Ltd.

[0039] In addition to the above, as the adhesive layer, without departing from the spirit of the present invention, the adhesive layer described in paragraphs 0026 to 00053 of Japanese Patent Application Publication No. 2017-200975, the adhesive layer described in paragraphs 0056 to 0060 of Japanese Patent Application Publication No. 2013-020130, the adhesive sheet of International Publication No. 2016 / 158827, the adhesive layer of paragraphs 0031 to 0032 of Japanese Patent Application Publication No. 2016-182791, and the rubber-based adhesive layer of paragraphs 0057 to 0084 of Japanese Patent Application Publication No. 2015-147837 may also be used, and these contents are incorporated herein.

[0040] In this embodiment, the thickness of the adhesive layer is not particularly limited, but is preferably 1 μm or more, more preferably 2 μm or more, preferably 20 μm or less, more preferably 15 μm or less, even more preferably 10 μm or less, and most preferably 5 μm or less. By setting the thickness of the adhesive layer within the above range, more appropriate adhesive properties and adhesive strength can be achieved.

[0041] <<Example of protective film>> An example of a protective film in this embodiment is a protective film having a polyolefin layer containing a polyolefin with a melting point of 150°C or higher and an adhesive layer. The protective film is used by attaching the adhesive layer side to the thermoplastic resin film when a heat-bending process is performed on a multilayer body for heat bending that contains a thermoplastic resin film containing a thermoplastic resin to obtain a heat-bent body. The maximum cross-sectional height Wt of the waviness curve of the surface of the polyolefin layer used to form the protective film is 0.30 μm or less, measured in accordance with JIS B 0601:2013, with a cutoff value of λ = 942 μm. Details of the polyolefin layer, adhesive layer, thermoplastic resin film, etc., are the same as described above, and the preferred ranges are also the same.

[0042] Furthermore, the total thickness of the protective film is preferably 30 μm or more, more preferably 35 μm or more, and even more preferably 40 μm or more. Setting the total thickness of the protective film to be above the lower limit tends to further suppress the occurrence of suction cup marks during heat bending. Furthermore, the total thickness of the protective film is preferably 200 μm or less, more preferably 150 μm or less, even more preferably 130 μm or less, even more preferably 120 μm or less, and even more preferably 110 μm or less. Setting the total thickness of the protective film to be below the upper limit tends to further improve its conformability to the molded product during heat bending.

[0043] <Polarizing film> The multilayer body for heat bending in this embodiment may have a polarizing film, and it is preferable that it has a polarizing film. A known polarizing film can be used, and an example is one in which iodine or a dichroic organic dye is adsorbed or impregnated onto a polyvinyl alcohol (PVA) film.

[0044] <Adhesive layer> Next, the adhesive layer used to bond the polarizing film and the thermoplastic resin film will be described. The adhesive can be a known adhesive, such as an acrylic adhesive, urethane adhesive, epoxy adhesive, silicone adhesive, or polyvinyl alcohol adhesive. Among these, a urethane adhesive is preferred. The thickness of the adhesive layer is typically 1 μm or more, and typically 30 μm or less.

[0045] <Wound body> The multilayer material for heat bending in this embodiment can be a winding body wound around a core material. In this embodiment, it is preferable to inspect the heat-bending multilayer body using an automated inspection device. When inspecting with an automated inspection device, a known masking film can be applied to the heat-bending multilayer body before the protective film is applied, and then the inspection can be performed using the automated inspection device. After the masking film is removed, the protective film of this embodiment can be applied. When inspected with an automated inspection device, no heat bending or other processing is performed, so an inexpensive, well-known masking film can be applied. Subsequently, when using it as a multilayer body for heat bending, it is preferable to apply the protective film of this embodiment. Since the protective film of this embodiment has sufficient performance to withstand heat bending, a multilayer body for heat bending having this protective film can achieve good heat bending while fulfilling the basic function of a protective film.

[0046] <Heat-bent processed body> Next, the applications of the multilayer body for heat bending according to this embodiment and the heat-bent products using the multilayer body for heat bending according to this embodiment will be described. An example of a heat-bent body according to this embodiment is a heat-bent body obtained by heat-bending the heat-bent multilayer body according to this embodiment. The heat-bending temperature is preferably determined based on the glass transition temperature of the thermoplastic resin contained in the thermoplastic resin film. Typically, the heat-bending temperature is between the glass transition temperature (Tg) of the thermoplastic resin contained in the thermoplastic resin film (Tg) of -5°C and Tg of +10°C.

[0047] In this embodiment, it is preferable to place the multilayer body for heat bending in a mold and then perform the heat bending process.

[0048] Figure 4 is a schematic diagram showing an example of using the heat-bending multilayer of this embodiment in the manufacture of a polarizing sheet, where 1 represents the heat-bending multilayer of this embodiment, 6 represents the polarizing film, 7 represents the other layers (for example, a multilayer including a polarizing film substrate and a protective film), and 8 represents the mold. In Figure 4, the heat-bending multilayer 1, the polarizing film 6, and the other layers 7 are shown separately, but normally, these are assembled into a multilayer sheet and then placed in the mold 8. In this embodiment, it is preferable that the heat-bending multilayer body 1 of this embodiment be arranged such that the protective film side of this embodiment becomes the convex portion (the side indicated by the arrow in Figure 4). Furthermore, when a polarizing sheet with a protective film (for example, the multilayer body 1 / polarizing film 6 / other layer 7 of this embodiment) is heat-bent using a mold 8, the protective film side of the multilayer body 1 for heat bending of this embodiment may be positioned closer to the mold than the thermoplastic resin film side, or it may be positioned further away. Preferably, when the multilayer body for heat bending of this embodiment is heat-bent using a mold, the protective film side is positioned closer to the mold 8 than the thermoplastic resin film side. The closer the protective film containing the polyolefin layer is to the mold, the easier it is for the waviness of the polyolefin layer to be transferred to the thermoplastic resin film, thus offering a greater advantage in using the multilayer body for heat bending of this embodiment. The other layer 7 may be the multilayer body for heat bending according to this embodiment.

[0049] More specifically, a polarizing sheet with a protective film (for example, a multilayer sheet consisting of reference numerals 1, 6, and 7 in Figure 4) is placed so that the multilayer body 1 for heat bending according to this embodiment is in contact with the mold (for example, a metal female mold) 8, and the pressure is reduced to make it adhere tightly to the mold 8, thereby obtaining the adsorbed punched piece. It is preferable to adsorb the polarizing sheet with the protective film onto the mold 8 and remove it from the mold 8 while adsorbing it using a male mold. Although the male mold used for adsorption and removal from the mold is sometimes also referred to as a mold, the mold in this embodiment is a mold having a mold for the desired heat bending shape.

[0050] In this embodiment, it is preferable to peel off the protective film after heat bending. In this embodiment, after peeling off the protective film, there is virtually no residue remaining at the edges of the thermoplastic resin film, and the surface quality of the thermoplastic resin film can be improved. Furthermore, the protective film can be prevented from adhering to the thermoplastic resin film.

[0051] The heat-bent body of this embodiment is also a heat-bent body obtained by heat-bending the heat-bent multilayer body of this embodiment, wherein the maximum value Wt(ta) of the maximum cross-sectional height Wt of the waviness curve, measured in accordance with JIS B 0601:2013 on the surface of the thermoplastic resin film in the heat-bent body, with a cutoff value of λ=942μm, is 0.35μm or less, and preferably Wt(ta) is the maximum value of Wt at each point divided into 6 equal angles over a circumference of 5mm inward from the outer circumference of the thermoplastic resin film.

[0052] The heat-bent body of this embodiment is a heat-bent multilayer body for heat bending, comprising a thermoplastic resin film containing a thermoplastic resin and a protective film provided on the surface of the thermoplastic resin film, wherein the maximum value Wt(ta) of the maximum cross-sectional height Wt of the waviness curve on the surface of the thermoplastic resin film when the protective film is peeled off from the heat-bent body, measured in accordance with JIS B 0601:2013 and with a cutoff value of λ=942μm, is 0.35μm or less, and preferably Wt(ta) is the maximum value of Wt at each point when the circumference of the thermoplastic resin film is divided into 6 equal angles over a circumference of 5 mm inward from the outer circumference.

[0053] The maximum value Wt(ta) of the maximum cross-sectional height Wt of the waviness curve on the surface of the thermoplastic resin film in the heat-bent workpiece is more preferably 0.32 μm or less, and more preferably 0.10 μm or more. By setting Wt(ta) to be below the upper limit and above the lower limit, the surface quality of the heat-bent workpiece after peeling off the protective film tends to be better. The preferred range of thermoplastic resin films and protective films is the same as described above.

[0054] The heat-bending multilayer and heat-bending products of this embodiment are preferably used as polarizing sheets for liquid crystal display devices, polarizing lenses (sunglass lenses, ski goggles, prescription eyeglass lenses, camera viewfinder lenses), covers for various instruments, automobile glass, train glass, polarizing sheets for in-vehicle display panels and electronic equipment housings, in-vehicle rearview mirrors, and silver mirrors for helmets. They are also preferably used as covers for lenses without a polarizing film and for various types of glass or glass substitute parts. The heat-bending products of this embodiment are particularly suitable for sunglasses. [Examples]

[0055] The present invention will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate, as long as they do not depart 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 other reasons, measurements can be taken using other instruments with equivalent performance.

[0056] 1. Raw materials <Polyolefin film> The materials used are shown in Tables 1-3 below. In the tables, PP refers to polypropylene, PP / PP / PP refers to a laminate consisting of three layers of polypropylene film, and PP / PP refers to a laminate consisting of two layers of polypropylene film.

[0057] <<Measuring the melting point>> The melting point (Tm) of the polyolefin film was determined by performing two cycles of heating and cooling under the differential scanning calorimetry (DSC) measurement conditions described below. The temperature during the heating phase of the second cycle was measured, and the peak of the endothermic peak was defined as the melting point. The unit is shown in °C. The starting temperature for measurement was 30°C, the heating rate was 10°C / min, the target temperature was 200°C, and the cooling rate was 10°C / min. The unit is °C. The sample size was approximately 1-2 mg, placed in an aluminum pan, and the measurement was performed. The measuring device used was a differential scanning calorimeter (DSC, manufactured by Hitachi High-Tech Science Corporation, model "DSC7020").

[0058] <<Weight of polyolefin film used for protective film formation>> The maximum cross-sectional height Wt (in μm) of the waviness curve of the polyolefin film was measured using a scanning white light interference microscope in accordance with JIS B 0601:2013. A scanning white-light interference microscope, model VS1800, manufactured by Hitachi High-Tech Science Corporation, was used. Measurements were taken under the following conditions. Measurement CCD camera: SONY XCL-C32 1 / 2-inch Telescope tube: 0.5x Objective lens: 5x Measurement mode: wave mode Wavelength filter: 530nm White Observation area: 2511 × 1883 μm The processing conditions involved performing a fourth-order surface correction, setting a cutoff value at a wavelength (λ) = 942 μm, and determining the maximum cross-sectional height Wt of the waviness curve after cutting off short wavelengths.

[0059] <<Haze of polyolefin film used for protective film formation>> The haze of the polyolefin film was measured using a haze meter "HM-150" manufactured by Murakami Color Technology Laboratory Co., Ltd., in accordance with JIS K 7136.

[0060] <Fabrication of protective film and adhesive layer> Regarding the adhesive layer, in Examples 1-5 and Comparative Examples 1-6, a urethane acrylate adhesive (manufactured by Shin-Nakamura Chemical Co., Ltd., UA-7100) was applied to the polyolefin films shown in Tables 1-3 using a bar coater, and a protective film was prepared by UV curing. In Comparative Examples 7 and 8, the substrate layer (back layer, intermediate layer) and the adhesive layer were formed in a single film by multilayer co-extrusion molding. In the table, UA indicates a urethane acrylate-based adhesive, and PE indicates a polyethylene-based adhesive.

[0061] <Polarizing sheet> A polyvinyl alcohol film (manufactured by Kuraray Co., Ltd., VF-PS#7500) was swollen in water at 35°C, dyed in an aqueous solution at 35°C containing the dichroic dyes Karayas Blue G (CIBlue 78), Sumilight Red 4B (CIRed 81), chrysophenine (CIYellow 12), and 10 g / L of anhydrous sodium sulfate, and then immersed in an aqueous solution containing 2.5 g / L of nickel acetate and 5 g / L of boric acid. The film was gradually stretched during this process until it was four times its original size. While maintaining the tension of the film, it was heated at 110°C for 3 minutes to obtain a polarizing film with a thickness of 30 μm. A polycarbonate film (manufactured by Mitsubishi Gas Chemical Company, E-2000, thickness: 320 μm, retardation value: 4900 nm) was used as a protective layer for the polarizing film described above. This polycarbonate film corresponds to the thermoplastic resin film of this embodiment, and the maximum cross-sectional height Wt(ta) of the waviness curve before the formation of the multilayer for heat bending was 0.001 μm. A thermosetting polyurethane adhesive (manufactured by Toyo Morton Co., Ltd., main component: BHS-6020A, curing agent: BHS-6020C, solid content concentration: 30% by mass) was applied to one side of the polarizing film described above. Then, a polycarbonate film (corresponding to the thermoplastic resin film in this embodiment) was bonded to it with the stretch axis aligned to obtain a one-sided laminated product. Next, the thermosetting polyurethane adhesive described above was applied to the unbonded side of the one-sided laminated product, and the polycarbonate film was bonded to it with the stretch axis aligned to obtain a polarizing sheet. A laminator (manufactured by M.C.K. Co., Ltd., MP-630A) was used for bonding, with the laminator roll set to 60°C, the roll rotation speed to 1.5 m / min, and the bonding pressure to 0.5 MPa.

[0062] Examples 1-5, Comparative Examples 1-8 <Fabrication of multilayer bodies for heat bending> Details of the polyolefin films shown in Tables 1-3 are described below. Example 1: Toyobo Co., Ltd., P1111, single layer construction (polypropylene), thickness: 50 μm, melting point: 160°C Example 2: Santox Corporation, CP-KT, single layer construction (polypropylene), thickness: 40 μm, melting point: 160°C Example 3: Okamoto Co., Ltd. ET-20, 3-layer construction (all polypropylene), thickness: 50 μm, melting point: 163°C Example 4: Okamoto Co., Ltd. ET-20, 3-layer construction (all polypropylene), thickness: 80 μm, melting point: 163°C Example 5: Okamoto Co., Ltd. ET-20, 3-layer construction (all polypropylene), thickness: 100 μm, melting point: 163°C Comparative Example 1: Toyobo Co., Ltd., P1146, single layer construction (polypropylene), thickness: 50 μm, melting point: 160°C Comparative Example 2: Toray Film Processing Co., Ltd., 3701J, single layer construction (polypropylene), thickness: 40 μm, melting point: 160°C Comparative Example 3: Toyobo Co., Ltd., P1153, single layer construction (polypropylene), thickness: 50 μm, melting point: 127°C Comparative Example 4: Futamura Chemical Co., Ltd., FRTK-G, 3-layer structure (all polypropylene), thickness: 50 μm, melting point: 165°C Comparative Example 5: Futamura Chemical Co., Ltd., FRTK-G, 3-layer structure (all polypropylene), thickness: 80 μm, melting point: 165°C Comparative Example 6: Idemitsu Unitech Co., Ltd., RT680CA, 3-layer structure (all polypropylene), thickness: 50 μm, melting point: 162°C Comparative Example 7: MX308N-50, manufactured by Nippon Matai Co., Ltd., 3-layer structure (back layer: polypropylene, middle layer: polypropylene, adhesive layer: polyethylene), thickness: 50 μm, melting point: 168°C Comparative Example 8: CF555F, manufactured by Toray Film Processing Co., Ltd., 3-layer structure (back layer: polypropylene, middle layer: polypropylene, adhesive layer: polyethylene), thickness: 66 μm, melting point: 164°C

[0063] Furthermore, during the heat bending process, the protective film positioned further from the mold than the thermoplastic resin film (polycarbonate film) in the polarizing sheet was FM-503P (base layer: polypropylene, adhesive layer: acrylic, thickness: 40 μm) manufactured by Daio Paper Processing Co., Ltd.

[0064] The multilayer body for heat bending was manufactured by placing the protective film prepared above (a protective film made using the polyolefin film and adhesive (the protective films listed in Tables 1-3)) onto the thermoplastic resin film (polycarbonate film) of the polarizing sheet so that the adhesive side of the protective film is in contact with the thermoplastic resin film (polycarbonate film) of the polarizing sheet, and placing the FM-503P on the other side of the polarizing sheet so that the adhesive side is in contact with it, and then laminating them together using a laminator. A laminator (MP-630A, manufactured by M.C.K. Co., Ltd.) was used for lamination, with the laminator roll set to 60°C, the roll rotation speed to 1.5 m / min, and the compression pressure to 0.5 MPa.

[0065] <Heat bending of multilayer materials for heat bending> The multilayer material for heat bending obtained above was punched out into strips measuring 79.5 x 56 mm for use as a twin-lens reflex lens using a hydraulic clicker (TC-55, manufactured by Toko Co., Ltd.). Next, the multilayer material for heat bending punched out into strips was heat-bent to obtain a heat-bent body. For the heat bending process, the multilayer body for heat bending was first preheated in a preheater with the protective film shown in Tables 1-3 facing downwards and the FM-503P facing upwards. Then, a suction cup arm was attached to the FM-503P side, and the body was moved onto a mold (metal female mold) with a measured temperature of 140°C and an equivalent of 8B (radius of curvature: 65.3 mm). The silicone rubber male mold was pressed against the body for 3 seconds, and the pressure was simultaneously reduced to 0.09 MPa to suction the multilayer body for heat bending onto the mold (metal female mold). After 9 minutes of suction in a molding furnace with controlled mold temperature, the suction cup arm was attached to the FM-503P side to obtain the heat-bent body. The protective films listed in Tables 1-3 were peeled off the obtained heat-bent bodies at a peeling speed of 1 m / sec and an adhesion strength of 0.2-0.5 N / 10 mm. The surface of the thermoplastic resin film (polycarbonate film) after peeling off the protective film (the side that was in contact with the protective film listed in Tables 1-3) was evaluated as follows.

[0066] <Measurement of Wt(ta) of thermoplastic resin film after removal of protective film> The maximum cross-sectional height Wt(ta) (unit: μm) of the waviness curve on the surface of the thermoplastic resin film (polycarbonate film) after peeling off the protective film described in Tables 1-3 from the heat-bent body obtained above was measured as follows. Specifically, for the surface of a thermoplastic resin film after heat bending and removal of the protective film, a 10 mm square measurement sample was cut from the outer edge of the thermoplastic resin film. This sample was placed on a microscope observation stand so that 5 mm from the outer edge was horizontal, and the maximum cross-sectional height Wt (unit: μm) of the waviness curve was measured using a scanning white light interference microscope. In addition, the outer length of the obtained heat-bent body (outer length of the thermoplastic resin film) was divided into six equal angles, and a 10 mm square measurement sample was similarly cut from each point and measured. The maximum value of the Wt measurements at the six points was defined as Wt(ta). Wt was measured using a scanning white light interference microscope in accordance with JIS B 0601:2013. A scanning white light interference microscope (VS1800) manufactured by Hitachi High-Tech Science Corporation was used. Measurements were performed under the following conditions. Measurement CCD camera: SONY XCL-C32 1 / 2-inch Telescope tube: 0.5x Objective lens: 5x Measurement mode: wave mode Wavelength filter: 530nm White Observation area: 2511 × 1883 μm The processing conditions involved performing a fourth-order surface correction, setting a cutoff value at a wavelength (λ) = 942 μm, and determining the maximum cross-sectional height Wt of the waviness curve after cutting off short wavelengths.

[0067] <Residue> The residue at the edges of the thermoplastic resin film after peeling off the protective film described in Tables 1-3 from the heat-bent body obtained above was measured as follows. Specifically, after heat bending, the protective film was peeled off, and the edge of the thermoplastic resin film was rubbed multiple times with a hand wearing rubber gloves. The determination was made based on the length of residue obtained from the edge. The protective film was removed from 10 heat-bent bodies to check for residue, and the maximum value among the 10 bodies was evaluated by classifying the residue length into three stages as described below. A: No residue was found (essentially none). B: There was some residue (less than 2mm) C: There was a large amount of residue (more than 2 mm).

[0068] <Surface degree> The surface quality of the thermoplastic resin film surface after peeling off the protective films listed in Tables 1-3 from the heat-bent bodies obtained above was measured as follows. Specifically, after heat bending, the protective film was removed from the heat-bent material, which was then suspended from a clip. Projection observation was performed using a special inspection lighting device (S-Light, manufactured by Irie Co., Ltd.) to assess the pinpoint unevenness. Five experts made their assessments using a criterion where Comparative Example 7 was rated "A," Example 3 was rated "B," and Comparative Example 5 was rated "C," and the final decision was made by majority vote. The projection observation photographs used for evaluation (in order: Comparative Example 7, Example 3, and Comparative Example 5) are shown in Figure 5. A: The surface is in good condition. B: The surface quality is slightly inferior. C: The surface quality is inferior.

[0069] <Fixed> The protective film was peeled off the heat-bent body obtained above at a peeling speed of 1 m / sec, and the results were evaluated as follows. A: It was able to be detached. C: The protective film was stuck to the thermoplastic resin film or the mold, and a portion of the protective film remained, or the protective film was stuck to the mold and peeled off during the heat bending process.

[0070] [Table 1]

[0071] [Table 2]

[0072] [Table 3]

[0073] As is clear from the above results, when the protective film was peeled off after heat bending, the multilayer body for heat bending of the present invention left little residue at the edges of the thermoplastic resin film, there was no adhesion of the protective film, and the surface quality of the thermoplastic resin film was excellent (Examples 1-5). In contrast, when the maximum cross-sectional height Wt of the waviness curve of the polyolefin film (polyolefin layer) was too large, the surface quality of the thermoplastic resin film was poor, or residue remained at the edges of the thermoplastic resin film (Comparative Examples 1-8). Also, when the melting point of the polyolefin film was low (Comparative Example 3), a portion of the protective film became fixed to the thermoplastic resin film or the mold.

[0074] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible without departing from the intent and scope of the invention. [Explanation of Symbols]

[0075] 1. Multilayer body for heat bending 2 Thermoplastic resin film 3 Adhesive layer 4. Polyolefin layer 41 Cross-sectional curve of the polyolefin layer 42. Swelling curve 43. Roughness Curve 5 Adhesive layer 6 Polarizing film 7 Other layers 8 molds

Claims

1. A multilayer body for heat bending, comprising a thermoplastic resin film containing a thermoplastic resin and a protective film provided on the surface of the thermoplastic resin film, The protective film comprises a polyolefin layer containing a polyolefin with a melting point of 150°C or higher, and an adhesive layer. The adhesive layer and the thermoplastic resin film are in contact, A multilayer body for heat bending, wherein the surface of the polyolefin layer used to form the protective film has a maximum cross-sectional height Wt of the waviness curve, measured in accordance with JIS B 0601:2013, with a cutoff value of λ = 942 μm, which is 0.30 μm or less.

2. The multilayer body for heat bending according to claim 1, wherein the adhesive layer comprises an acrylic adhesive and / or a urethane acrylate adhesive.

3. The multilayer body for heat bending according to claim 1 or 2, wherein the haze of the polyolefin layer, as measured in accordance with JIS K 7136, is 15% or less.

4. The multilayer body for heat bending according to claim 1 or 2, wherein the polyolefin layer comprises polypropylene.

5. The multilayer body for heat bending according to claim 1 or 2, wherein the thermoplastic resin film comprises at least one selected from the group consisting of polycarbonate, polyamide, poly(meth)acrylic acid ester, and polyester.

6. The heat-bending multilayer according to claim 1 or 2, wherein when the heat-bending multilayer is subjected to heat bending using a mold, the protective film side is positioned closer to the mold than the thermoplastic resin film side.

7. The multilayer body for heat bending according to claim 1 or 2, wherein the maximum cross-sectional height Wt of the waviness curve of the surface of the polyolefin layer used to form the protective film is 0.01 μm or more, as measured in accordance with JIS B 0601:2013, and a cutoff value of λ = 942 μm is set.

8. The thickness of the polyolefin layer is 20 to 150 μm. The thickness of the adhesive layer is 1 to 20 μm. The thickness of the thermoplastic resin film is 100 to 1000 μm. A multilayer body for heat bending according to claim 1 or 2.

9. Furthermore, it includes a polarizing film, The protective film, the thermoplastic resin film, and the polarizing film are laminated in that order. A multilayer body for heat bending according to claim 1 or 2.

10. A multilayer body for heat bending according to claim 1 or 2, for use in manufacturing polarizing sheets.

11. The adhesive layer comprises an acrylic adhesive and / or a urethane acrylate adhesive. The haze of the aforementioned polyolefin layer, as measured in accordance with JIS K 7136, is 15% or less. The polyolefin layer comprises polypropylene, The thermoplastic resin film comprises at least one selected from the group consisting of polycarbonate, polyamide, poly(meth)acrylic acid ester, and polyester. The maximum cross-sectional height Wt of the waviness curve of the surface of the polyolefin layer used to form the protective film, measured in accordance with JIS B 0601:2013 and with a cutoff value of λ = 942 μm, is 0.01 μm or more. The thickness of the polyolefin layer is 20 to 150 μm. The thickness of the adhesive layer is 1 to 20 μm. The thickness of the thermoplastic resin film is 100 to 1000 μm. Furthermore, it includes a polarizing film, The protective film, the thermoplastic resin film, and the polarizing film are laminated in that order. A multilayer body for heat bending according to claim 1.

12. The heat-bending multilayer according to claim 11, wherein when the heat-bending multilayer is subjected to heat bending using a mold, the protective film side is positioned closer to the mold than the thermoplastic resin film side.

13. A heat-bent body obtained by heat-bending a multilayer body for heat bending according to claim 1, 2, 11, or 12.

14. A heat-bent body obtained by heat-bending a multilayer body for heat bending according to claim 1, 2, 11, or 12, A heat-bent body in which the surface of the thermoplastic resin film in the heat-bent body is measured in accordance with JIS B 0601:2013, and the maximum value Wt(ta) of the maximum cross-sectional height Wt of the waviness curve when a cutoff value of λ = 942 μm is set is 0.35 μm or less, and Wt(ta) is the maximum value of Wt at each point when the circumference of the thermoplastic resin film is divided into 6 equal angles over a circumference of 5 mm inward from the outer circumference.

15. A heat-bent multilayer body for heat bending, comprising a thermoplastic resin film containing a thermoplastic resin and a protective film provided on the surface of the thermoplastic resin film, A heat-bent body in which, when the protective film is peeled off from the heat-bent body, the maximum value Wt(ta) of the maximum cross-sectional height Wt of the waviness curve on the surface of the thermoplastic resin film is measured in accordance with JIS B 0601:2013, and a cutoff value of λ = 942 μm is set, and the maximum value Wt(ta) is 0.35 μm or less, and the Wt(ta) is the maximum value of Wt at each point when the circumference of the thermoplastic resin film is divided into 6 equal angles over a circumference of 5 mm inward from the outer edge.

16. The sunglasses according to claim 13, comprising the heat-bent body.

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