Flat-shaped formed body and multilayer body

Abstract

Provided are a plate-shaped molded body and a multi-layer body which have few optical defects when bent and which have excellent flex resistance. The plate-shaped molded body contains bisphenol AP-type polycarbonate having a glass transition temperature of 180°C or greater, wherein the plate-shaped molded body has: a photoelastic coefficient of no more than 85×10-12m2 / N; a thickness of no more than 75μm; and haze of no more than 2.0%.

Description

Technical Field

[0001] The present invention relates to a flat molded body and a laminate. In particular, it relates to a flat molded body using polycarbonate suitable for a base material of a transparent conductive film.

Background Art

[0002] Polycarbonate is a general-purpose engineering plastic excellent in transparency, impact resistance, heat resistance, dimensional stability, etc., and is used in various fields. One of its applications is in the optical field taking advantage of its excellent transparency characteristics. General polycarbonate is derived from bisphenol A and has a relatively high refractive index, so its use as an optical lens has been studied. For example, Patent Document 1 describes that a polycarbonate obtained by copolymerizing specific structural units is excellent in optical properties and impact resistance and can be used for spectacle lenses and camera lenses. Further, Patent Document 2 discloses an optical component made of an aromatic polycarbonate, and specific examples of the optical component include an optical disc substrate, a pickup lens, etc.

[0003] Furthermore, the use of polycarbonate in various films has also been studied. For example, films for electronic and electrical equipment parts, optical films, heat-resistant films, electrical insulating films, etc. can be mentioned (Patent Document 3). Patent Document 3 describes a polycarbonate film formed by molding a polycarbonate copolymer having specific structural units, and it is particularly described that it is excellent in mechanical strength, heat resistance, etc. Furthermore, taking advantage of the excellent properties of polycarbonate, research and development are actively carried out to expand into a wide range of technical fields, but many are still in progress, and there is much room for improvement in its properties and the like. In the future, since it is expected to study the use of polycarbonate in a wider range of film applications, the development of polycarbonate films having properties suitable for each application is desired.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, in recent displays and touch panels of video and communication devices, characteristics such as foldable types and bendable types that can be bent have been emphasized. For the base materials of these displays and touch panels, resin film materials rather than glass are considered optimal. However, when the display is bent in this way, problems such as image blurring and double imaging occur. These problems are caused by birefringence that occurs in the optical path when the resin film base material is bent. Also, in the above-mentioned foldable displays and the like, the resin film base material may be required to have bend resistance. An object of the present invention is to solve such problems, and an object is to provide a flat molded body with few optical defects when bent and excellent bend resistance, and a multilayer body including the flat molded body.

Means for Solving the Problems

[0006] As a result of investigations by the present inventors under the above problems, it has been found that the above problems can be solved by using a flat molded body having a low photoelastic coefficient and a thin thickness. Specifically, the above problems have been solved by the following means. <1>A flat molded body containing bisphenol AP type polycarbonate having a glass transition temperature of 180°C or higher, wherein the photoelastic coefficient is 85×10 -12 m 2 / N or less, the thickness is 75 μm or less, and the haze is 2.0% or less. <2>Furthermore, it contains bisphenol A polycarbonate, and among the polycarbonates contained in the flat molded body, the proportion of the bisphenol A P-type polycarbonate is 15% by mass or more and 90% by mass or less. The flat molded body according to <1>. <3>The glass transition temperature of the flat molded body is 154°C or higher. The flat molded body according to <1> or <2>. <4>Furthermore, it contains an antioxidant. The flat molded body according to any one of <1> to <3>. <5>Furthermore, it contains a release agent. The flat molded body according to any one of <1> to <4>. <6>Cut into a size of 75×25 mm, and in accordance with JIS C5016, when a bending test is performed using an FPC bending tester with a curvature radius of 1.5 mm on the bending surface and 200,000 bending times, it does not break. The flat molded body according to any one of <1> to <5>. <7>It is used as a base material for a transparent conductive film. The flat molded body according to any one of <1> to <6>. <8>A multilayer body having the flat molded body according to any one of <1> to <7>. <9>It has a curable resin layer on one side or both sides of the flat molded body. The multilayer body according to <8>. <10>It has a refractive index adjustment layer on one side or both sides of the flat molded body. The multilayer body according to <8> or <9>. <11>It has a protective film on one side or both sides of the flat molded body. The multilayer body according to any one of <8> to <10>. <12>It has a transparent conductive layer on the flat molded body. The multilayer body according to any one of <8> to <11>. <13>The transparent conductive layer contains one or more of ATO (antimony-doped indium oxide), FTO (fluorine-doped tin oxide), AZO (aluminum-doped zinc oxide), GZO (gallium-doped zinc oxide), ITO (indium tin composite oxide), Ag, Cu, Au, and carbon nanotubes. The multilayer body according to <12>. <14>A transparent conductive film. The multilayer body according to <12> or <13>.

[0007] In any of the above flat-shaped formed bodies, further, a flat-shaped formed body having a thickness of less than 50 μm (preferably 49 μm or less). In any of the above flat molded articles, a flat molded article further having a retardation (Rth) in the thickness direction of 38 nm or less. <c>A transparent conductive film having a transparent conductive layer, a curable resin layer, and a flat molded body in that order, wherein the flat molded body is any one of the above flat molded bodies. <d>A transparent conductive film having a transparent conductive layer, a refractive index adjusting layer, a curable resin layer, and a flat molded body in this order, wherein the flat molded body is any one of the above flat molded bodies. <e>A transparent conductive film having a transparent conductive layer, a refractive index adjusting layer, a curable resin layer, a flat-shaped molded body, and a protective film in this order, wherein the flat-shaped molded body is any one of the above flat-shaped molded bodies.

Advantages of the Invention

[0008] It has become possible to provide a flat-shaped molded body with few optical defects when bent and excellent flex resistance, and a multilayer body including the flat-shaped molded body.

Brief Description of the Drawings

[0009] < / e> < / d> < / c>

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0010] Hereinafter, the content of the present invention will be described in detail. 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. In this specification, various physical property values and characteristic values are those at 23°C unless otherwise specified. The flat-shaped molded body and the multilayer body in this specification are each intended to include those having the shape of a film or a sheet. "Film" and "sheet" each refer to a molded body having a small thickness and being generally flat with respect to the length and width. Further, the "film" in this specification may be single-layer or multi-layer. In this specification, "parts by mass" indicates the relative amount of a component, and "mass%" indicates the absolute amount of a component.

[0011] The flat-shaped molded body of the present invention is a flat-shaped molded body containing a bisphenol AP type polycarbonate having a glass transition temperature of 180°C or higher, and has a photoelastic coefficient of 85×10 -12 m 2 / N or less, a thickness of 75 μm or less, and a haze of 2.0% or less. In the present invention, by using a bisphenol AP type polycarbonate having a glass transition temperature of 180°C or higher, reducing its thickness, and lowering its photoelastic coefficient, it is possible to obtain a flat molded article with a haze as low as 2.0% or less, excellent transparency, few optical defects when bent, and excellent flexural resistance. Furthermore, it is also possible to reduce the heat shrinkage rate of the flat molded article. This mechanism is that by lowering the photoelastic coefficient, the resin is less likely to generate birefringence due to an external force. Therefore, it is presumed that the birefringence generated when an external force is applied by a molding roll during film forming can be reduced, and the optical defects when bent can be suppressed. The flexural resistance is presumably because by reducing the film thickness, the stress generated on the film surface during bending can be reduced. Hereinafter, the present invention will be described in detail.

[0012] <Bisphenol AP type polycarbonate having a glass transition temperature of 180°C or higher> The flat molded article of the present invention contains a bisphenol AP type polycarbonate having a glass transition temperature of 180°C or higher. By using a bisphenol AP type polycarbonate with a high glass transition temperature, high heat resistance and a low photoelastic coefficient can be achieved while maintaining film processability. That is, by replacing the methyl group in the side chain of bisphenol A type polycarbonate with a phenyl group, the heat resistance can be improved and the optical anisotropy can be reduced. Bisphenol AP type polycarbonate refers to a resin having carbonate units derived from bisphenol AP (1,1-bis(4-hydroxyphenyl)-1-phenylethane) and its derivatives, and preferably has a structural unit represented by the following formula (A-1).

Chemical formula

[0013] The structural unit represented by formula (A-1) is preferably the structural unit represented by the following formula (A-2).

Chemical formula

[0014] The structural unit represented by formula (A-2) is preferably the structural unit represented by the following formula (A-3). * in the formula represents the bonding position with other sites (other structural units or terminal groups).

Chemical formula

[0015] In the bisphenol AP type polycarbonate, the content of the structural unit represented by the formula (A-1) is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more in all the structural units excluding the terminal groups. The upper limit is not particularly limited, and it may be 100 mol% of the structural unit represented by the formula (A-1). The structural unit derived from bisphenol AP may be only one kind or composed of two or more kinds. Particularly preferred as the bisphenol AP type polycarbonate is a resin in which substantially all is the structural unit represented by the formula (A-1). Here, substantially all means specifically 99.0 mol% or more of all the structural units excluding the terminal groups, preferably 99.5 mol% or more, and more preferably 99.9 mol% or more. The bisphenol AP type polycarbonate may have other structural units different from the carbonate units derived from bisphenol AP and its derivatives. Examples of the dihydroxy compound constituting such other structural units include, for example, the aromatic dihydroxy compounds described in paragraph 0014 of JP-A-2018-154819, the content of which is incorporated herein.

[0016] The method for producing the bisphenol AP type polycarbonate used in the present invention is not particularly limited, and any method can be adopted. Examples thereof include an interfacial polymerization method, a melt transesterification method, a pyridine method, a ring-opening polymerization method of a cyclic carbonate compound, and a solid-phase transesterification method of a prepolymer.

[0017] In the present invention, the glass transition temperature (Tg) of the bisphenol AP type polycarbonate has a lower limit of 180°C or higher, preferably 181°C or higher, more preferably 182°C or higher, and even more preferably 183°C or higher. By setting the lower limit value or higher, the heat shrinkage rate of the flat molded body can be made smaller. The upper limit is, for example, 210°C or lower, preferably 200°C or lower, and more preferably 190°C or lower. By setting the upper limit value or lower, good film formability can be more effectively maintained. In addition, when two or more types of bisphenol AP type polycarbonates are contained in the flat-shaped molded body, the measured value of the glass transition temperature of the mixture is treated as the glass transition temperature of the bisphenol AP type polycarbonate. The glass transition temperature (Tg) is measured by the method described in the examples below.

[0018] In the present invention, the viscosity average molecular weight of the bisphenol AP type polycarbonate preferably has a lower limit of 15,000 or more, more preferably 17,500 or more, and even more preferably 20,000 or more. By setting the value to be not less than the above lower limit, the flexural resistance can be further improved. The upper limit is preferably 25,000 or less, more preferably 22,000 or less, and even more preferably 21,500 or less. By setting the value to be not more than the above upper limit, good film formability can be effectively maintained. In addition, when two or more types of bisphenol AP type polycarbonates are contained in the flat-shaped molded body, the measured value of the mixture is treated as the viscosity average molecular weight of the bisphenol AP type polycarbonate.

[0019] Here, the viscosity average molecular weight [Mv] of the polycarbonate in the present invention uses methylene chloride as a solvent, and the intrinsic viscosity [η] (unit: dL / g) at a temperature of 25°C is determined using an Ubbelohde viscometer. The Schnell viscosity formula, that is, η = 1.23×10 -4 Mv 0.83 means the value calculated from. The intrinsic viscosity [η] is a value measured for the specific viscosity [η sp at each solution concentration [C] (g / dL) and calculated by the following formula.

Equation

[0020] The content of bisphenol AP type polycarbonate is preferably 15% by mass or more, more preferably 27% by mass or more, still more preferably 40% by mass or more, even more preferably 50% by mass or more, yet even more preferably 55% by mass or more, still even more preferably 60% by mass or more, and may be 65% by mass or more in the polycarbonate contained in the flat molded article. As the upper limit value, it is preferably 90% by mass or less, more preferably 85% by mass or less, still more preferably 78% by mass or less, even more preferably 75% by mass or less, yet even more preferably 72% by mass or less. By setting the range in this way, high heat resistance and a low photoelastic coefficient can be achieved while maintaining film processability. One or more than two kinds of bisphenol AP type polycarbonate may be used. When using two or more kinds, the total amount thereof falls within the above range.

[0021] <Bisphenol A type polycarbonate> The flat molded article of the present invention preferably further contains bisphenol A type polycarbonate. By including bisphenol A type polycarbonate, film formability can be effectively maintained. Bisphenol A type polycarbonate refers to a resin having carbonate units derived from bisphenol A (2,2-bis(4-hydroxyphenyl)propane) and its derivatives, and preferably has a structural unit represented by the following formula (B-1). * in the formula represents the bonding position.

Chemical formula

Chemical formula

[0022] In bisphenol A polycarbonate, the content of the structural unit represented by formula (B-1) is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more in all the structural units excluding the end groups. The upper limit is not particularly limited, and all 100 mol% excluding the end groups may be the structural unit represented by formula (B-1). Particularly preferably, the bisphenol A polycarbonate is a resin in which substantially all the structural units excluding the end groups are composed of the structural units of formula (B-1). Here, substantially the entire amount specifically means 99.0 mol% or more of all the structural units excluding the end groups, preferably 99.5 mol% or more, and more preferably 99.9 mol% or more. The bisphenol A polycarbonate may have other structural units other than the carbonate units derived from bisphenol A and its derivatives. Examples of the dihydroxy compound constituting such other structural units include, for example, the aromatic dihydroxy compounds described in paragraph 0014 of JP-A-2018-154819, and the contents thereof are incorporated herein.

[0023] The production method of bisphenol A polycarbonate is not particularly limited, and any method can be adopted. Examples thereof include the interfacial polymerization method, the melt transesterification method, the pyridine method, the ring-opening polymerization method of a cyclic carbonate compound, and the solid-phase transesterification method of a prepolymer.

[0024] In the present invention, the viscosity-average molecular weight of bisphenol A polycarbonate is preferably 8,000 or more, more preferably 10,000 or more, and even more preferably 12,000 or more as the lower limit. By setting it to be not less than the lower limit value, it tends to be more excellent in flexural resistance. As the upper limit, it is preferably 30,000 or less, more preferably 20,000 or less, and even more preferably 18,000 or less. By setting it to be not more than the upper limit value, the moldability into a flat molded body tends to be further improved. In addition, when two or more kinds of bisphenol A polycarbonate are contained in the flat molded body, the measured value of the mixture is treated as the viscosity-average molecular weight of bisphenol A polycarbonate.

[0025] The glass transition temperature (Tg) of bisphenol A polycarbonate is preferably 135°C or more, more preferably 138°C or more, and even more preferably 140°C or more. By setting it to be not less than the lower limit value, the heat shrinkage rate of the flat molded body can tend to be made smaller. As the upper limit, it is preferably 160°C or less, and further may be 150°C or less, and further may be 145°C or less. In addition, when two or more kinds of bisphenol A polycarbonate are contained in the flat molded body, the measured value of the glass transition temperature of the mixture is treated as the glass transition temperature of bisphenol A polycarbonate. The glass transition temperature (Tg) is measured by the method described in the examples below.

[0026] The content of bisphenol A polycarbonate is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 23% by mass or more, even more preferably 25% by mass or more, and still even more preferably 28% by mass or more in the polycarbonate contained in the flat molded body. As the upper limit value, it is preferably 85% by mass or less, more preferably 73% by mass or less, still more preferably 60% by mass or less, even more preferably 50% by mass or less, still even more preferably 45% by mass or less, still even more preferably 40% by mass or less, and may be 35% by mass or less. By setting it within such a range, high heat resistance and a low photoelastic coefficient can be achieved while maintaining film processability. One kind or two or more kinds of bisphenol A polycarbonate may be used. When two or more kinds are used, the total amount thereof falls within the above range.

[0027] In the flat molded body of the present invention, it is preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 97% by mass or more, even more preferably 98% by mass or more, and may be 99% by mass or more of polycarbonate.

[0028] The polycarbonate contained in the flat molded article of the present invention may consist only of bisphenol AP type polycarbonate, or may consist only of bisphenol AP type polycarbonate and bisphenol A type polycarbonate. In addition to bisphenol AP type polycarbonate, it may contain other polycarbonates, or in addition to bisphenol AP type polycarbonate and bisphenol A type polycarbonate, it may contain other polycarbonates. In the present invention, it is preferable that 99% by mass or more of the total polycarbonate contained in the flat molded article is composed of bisphenol AP type polycarbonate and bisphenol A type polycarbonate. By using a blend of bisphenol AP type polycarbonate and bisphenol A type polycarbonate, good film formability can be maintained more effectively.

[0029] <Antioxidant> The flat molded article of the present invention preferably contains an antioxidant. Examples of the antioxidant include amine-based antioxidants, phosphorus-based antioxidants, phenol-based antioxidants, thioether-based antioxidants, etc. Phosphorus-based antioxidants and phenol-based antioxidants (more preferably hindered phenol-based antioxidants and / or semi-hindered phenol-based antioxidants) are preferred. As the phosphorus-based antioxidant, a phosphite compound represented by the following formula (1) or formula (2) is preferred.

Chemical formula

Chemical formula

[0030] In the above formula (1), R 11 and / or R 12 The alkyl group represented by each is preferably an alkyl group having 1 to 10 carbon atoms, which is linear or branched. R 11 and / or R 12 When it is an aryl group, an aryl group represented by the following formula (1-a), formula (1-b), or formula (1-c) is preferred. * in the formula represents the bonding position.

[0031]

Chemical formula

[0032] Examples of the phenolic antioxidant include hindered phenolic antioxidants and semi-hindered phenolic antioxidants. As the phenolic antioxidant, the phenolic antioxidants described in paragraph 0041 of JP-A-2019-002023 and the phenolic antioxidants described in paragraphs 0033 to 0034 of JP-A-2019-056035 are preferably used, and the contents thereof are incorporated herein.

[0033] Details of the antioxidant can be referred to the description in paragraphs 0057 to 0061 of JP-A-2017-031313, and the contents thereof are incorporated herein.

[0034] The content of the antioxidant is preferably 0.005 parts by mass or more, more preferably 0.007 parts by mass or more, still more preferably 0.01 parts by mass or more, based on 100 parts by mass of the polycarbonate. Also, the upper limit of the content of the antioxidant is preferably 0.4 parts by mass or less, more preferably 0.3 parts by mass or less, still more preferably 0.2 parts by mass or less, and even more preferably 0.1 parts by mass or less, based on 100 parts by mass of the polycarbonate. By setting the content of the antioxidant to 0.005 parts by mass or more, a flat molded article with better hue and heat discoloration resistance can be obtained. Also, by setting the content of the antioxidant to 0.4 parts by mass or less, a flat molded article with good wet heat stability can be obtained without deteriorating the heat discoloration resistance. Also, when using a combination of a phosphorus-based antioxidant and a phenolic antioxidant (preferably a hindered phenolic antioxidant and / or a semi-hindered phenolic antioxidant) as the antioxidant, the content thereof is preferably in the range of 0.001 to 0.2 parts by mass of the phosphorus-based antioxidant and 0.001 to 0.2 parts by mass of the phenolic antioxidant with respect to 100 parts by mass of the polycarbonate.

[0035] Only one type of antioxidant 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.

[0036] <Release agent> The flat molded article of the present invention may contain a release agent. By including a release agent, the winding property when winding up the flat molded article can be improved, or the releasability when molding using a mold can be further improved. The type of the release agent is not particularly defined, but examples of the release agent include at least one compound selected from the group consisting of aliphatic carboxylic acids, esters of aliphatic carboxylic acids and alcohols, aliphatic hydrocarbon compounds having a number average molecular weight of 200 to 15000, polyethers having a number average molecular weight of 100 to 5000, and polysiloxane-based silicone oils. Details of the release agent can be referred to the descriptions in paragraphs 0035 to 0039 of WO2015 / 190162, and this content is incorporated herein.

[0037] The content of the release agent is preferably 0.001 part by mass or more, more preferably 0.005 part by mass or more, and still more preferably 0.007 part by mass or more, based on 100 parts by mass of the polycarbonate. Also, the upper limit of the content of the release agent is preferably 1.0 part by mass or less, more preferably 0.5 part by mass or less, still more preferably 0.1 part by mass or less, and even more preferably 0.05 part by mass or less, based on 100 parts by mass of the polycarbonate. Only one type of release agent 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.

[0038] <Other components> In addition to the above components, the flat molded article of the present invention may contain an ultraviolet absorber, a heat stabilizer, a flame retardant, a flame retardant aid, a colorant, an antistatic agent, a fluorescent brightening agent, an anti-fogging agent, a fluidity improver, a plasticizer, a dispersant, an antibacterial agent, an anti-blocking agent, an impact improver, a sliding improver, a hue improver, an acid trap agent, etc. These components may be used alone or in combination of two or more.

[0039] <Method for manufacturing a flat molded article> The flat molded article of the present invention can be produced by appropriately using a known method, and it is preferable to use extrusion molding, cast molding, etc. As an example of extrusion molding, a semi-molten sheet obtained by melting and kneading pellets, flakes or powders to which additives are optionally added in a polycarbonate component with an extruder and then extruding from a T-die or the like is sandwiched between polishing rolls or the like while being cooled and solidified to obtain a flat molded article. The extruder may be a single-screw extruder or a twin-screw extruder, and either a vented or non-vented one can be used. As an example of cast molding, a method of sufficiently dissolving the components constituting the flat molded article in a solvent, casting the obtained solution onto a support to form a film-like cast film, and drying this cast film by heating or the like to obtain a flat molded article can be mentioned. Regarding the solvent, any solvent that can form a cast film can be used without limitation, but for example, methylene chloride, dioxolane, etc. are preferably used.

[0040] <Properties of the flat-shaped molded body> Next, the properties of the flat-shaped molded body of the present invention will be described.

[0041] The flat-shaped molded body of the present invention has a thickness of 75 μm or less, preferably 70 μm or less, more preferably 65 μm or less, still more preferably 60 μm or less, even more preferably 55 μm or less, and may be less than 50 μm or 49 μm or less. By setting the thickness to 75 μm or less, a flat-shaped molded body excellent in flexural resistance and transparency can be obtained. The lower limit of the thickness of the flat-shaped molded body of the present invention is preferably 20 μm or more, more preferably 25 μm or more, and may be 30 μm or more. By setting the value to be equal to or higher than the above lower limit value, the strength of the film can be maintained and breakage during molding can be suppressed.

[0042] The flat-shaped molded body of the present invention preferably has a glass transition temperature of 154 °C or higher, more preferably 155 °C or higher, still more preferably 160 °C or higher, and may be 165 °C or higher or 170 °C or higher. By setting the value to be equal to or higher than the above lower limit value, the heat shrinkage rate of the film tends to be smaller. The upper limit of the glass transition temperature of the flat-shaped molded body of the present invention is not particularly defined, but 190 °C or lower is practical. Examples of methods for increasing the glass transition temperature of the flat-shaped molded body include increasing the proportion of bisphenol AP type polycarbonate in the flat-shaped molded body. The glass transition temperature is measured according to the description of the examples described later.

[0043] The flat-shaped molded article of the present invention has a haze of 2.0% or less, preferably 1.5% or less, more preferably 1.0% or less, even more preferably 0.8% or less, still more preferably 0.5% or less, even more preferably less than 0.3%, and even more preferably 0.25% or less. Also, although the haze of the flat-shaped molded article of the present invention is preferably low, the lower limit is preferably 0.01% or more for practical purposes. The haze of the flat-shaped molded article can be lowered by using polycarbonate as the main component of the flat-shaped molded article, reducing the thickness of the flat-shaped molded article, and the like.

[0044] The flat-shaped molded article of the present invention has a photoelastic coefficient of 85×10 -12 m 2 / N or less. By adopting such a configuration, optical defects during bending can be effectively suppressed. Also, it becomes possible to lower the retardation (Rth) in the thickness direction. The photoelastic coefficient is preferably 70×10 -12 m 2 / N or less, more preferably 65×10 -12 m 2 / N or less, even more preferably 60×10 -12 m 2 / N or less, still more preferably 58×10 -12 m 2 / N or less. By setting it below the above upper limit value, there is a tendency to more effectively suppress optical defects during bending. Although the photoelastic coefficient is preferably low, for example, 45×10 -12 m 2 / N or more is practical. Examples of methods for setting the photoelastic coefficient to a desired value include adopting bisphenol AP type polycarbonate as the polycarbonate. The photoelastic coefficient is measured according to the method described in the examples below.

[0045] The flat-shaped molded body of the present invention is preferably not broken when cut into a size of 75×25 mm and subjected to a bending resistance test using an FPC bending tester in accordance with JIS C5016 with a bending surface curvature radius of 1.5 mm and a bending number of 200,000 times. Incidentally, FPC is an abbreviation for Flexible Printed Circuit Board or Flexible Printed Circuit. Details of the bending resistance test follow the method described in the examples below.

[0046] The flat-shaped molded body of the present invention can reduce the retardation (Rth) in the thickness direction. Specifically, it can be 38 nm or less, more preferably 35 nm or less, and particularly preferably 30 nm or less. The lower limit of Rth of the flat-shaped molded body of the present invention is preferably lower, but for example, 3 nm or more is practical. Rth is measured, for example, according to the following method. [Method for Measuring Retardation in the Thickness Direction] Using an ellipsometer (for example, "M-220" manufactured by JASCO Corporation), measure the refractive index n in the direction that gives the maximum refractive index in the in-plane direction of each layer of the flat-shaped molded body x , the refractive index n in the direction perpendicular to the direction of n x in the in-plane direction, and the refractive index n in the thickness direction y . Calculate the retardation Rth (nm) in the thickness direction from these n z , n x , n y , n z and the thickness of the flat-shaped molded body. [Measurement Conditions] Spectroscopic method: Double monochromatic method Measurement wavelength: 550 nm Incident angle: 90° Bandwidth: 0.5 mm Response: 2 sec Start tilt angle and end tilt angle of the anisotropy analysis stage: -50°, 50° Measurement interval: 5°

[0047] [Usage] The flat-shaped molded body of the present invention may be used as a single-layer body (single-layer film, single-layer sheet) or as a multi-layer body. The flat-shaped molded body as a single-layer body is useful as an optical film, a base material, a protective film, etc. In particular, the single-layer body of the present invention is suitable for use as a base material for a transparent conductive film (particularly, for a base material of a transparent conductive layer).

[0048] Next, a multi-layer body using the flat-shaped molded body of the present invention will be described. The multi-layer body of the present invention has the flat-shaped molded body of the present invention. The multi-layer body of the present invention preferably has a curable resin layer on one or both surfaces of the flat-shaped molded body. Further, the multi-layer body of the present invention preferably has a refractive index adjustment layer on one or both surfaces (preferably on one surface) of the flat-shaped molded body. Further, the multi-layer body of the present invention preferably has a protective film on one or both surfaces (preferably on one surface) of the flat-shaped molded body. Further, the multi-layer body of the present invention preferably has a transparent conductive layer on the flat-shaped molded body.

[0049] The multi-layer body of the present invention is preferably used for a transparent conductive film. FIG. 1 is an example of a transparent conductive film, where 1 indicates a transparent conductive layer, 2 indicates a refractive index adjustment layer, 3 indicates a curable resin layer, 4 indicates a flat-shaped molded body, and 5 indicates a protective film.

[0050] The material of the transparent conductive layer is not particularly limited as long as it has conductivity, but preferably contains one or more of ATO (antimony-doped indium oxide), FTO (fluorine-doped tin oxide), AZO (aluminum-doped zinc oxide), GZO (gallium-doped zinc oxide), ITO (indium tin composite oxide), Ag, Cu, Au, and carbon nanotubes. The thickness of the transparent conductive layer is preferably 1 to 30 nm. The transparent conductive layer is used, for example, as a transparent electrode layer.

[0051] The refractive index adjustment layer is a layer that adjusts the refractive index and can also make patterns after etching, etc. less visible. The refractive index adjustment layer may be a layer (high refractive index layer) having a refractive index close to that of the transparent conductive layer, or may be composed of both a high refractive index layer and a low refractive index layer. In particular, a configuration including a high refractive index layer and a low refractive index layer is preferable starting from the side closer to the transparent conductive layer. Details of the high refractive index layer and the low refractive index layer can be referred to the descriptions in paragraphs 0071 to 0095 of JP-A-2019-124913, and this content is incorporated herein.

[0052] The curable resin layer can impart hardness, chemical resistance, scratch resistance, etc. to the multilayer body. As the curable resin layer, for example, a thermosetting resin or an energy ray curable resin having a pencil hardness of H or more can be used. Examples of the energy ray curable resin include ultraviolet curable resins. Specifically, various types such as acrylic, polyester, urethane, silicone, amide, and epoxy are included, and ultraviolet curable monomers, oligomers, polymers, etc. are included. There is no particular limitation on the thickness of the curable resin layer, but it is preferably 0.5 to 10 μm.

[0053] As the protective film, a resin film is preferable. Examples of the resin constituting the resin film include polypropylene, polyethylene, polyethylene terephthalate, polycarbonate, cycloolefin, polyarylate, polysulfone, polyamide, and polyimide. There is no particular limitation on the thickness of the protective film, but it is preferably 10 to 100 μm.

[0054] The above transparent conductive film is not limited to the configuration of FIG. 1. For example, in FIG. 1, a curable resin layer may further be provided between the flat molded body and the protective film. Also, an adhesive layer, an adhesive layer, etc. may be provided between the respective constituent layers shown in FIG. 1. In particular, an embodiment having an adhesive layer on the surface of the protective film is preferable. In addition, the transparent conductive film of FIG. 1 may further have functional layers such as a hard coat layer, an antiglare layer, an antireflection layer, a low reflection layer, a conductive layer, an antiblocking layer, an antistatic layer, a coloring layer, an ultraviolet absorption layer, and an antifouling layer. Details of the hard coat layer can be referred to the descriptions in paragraphs 0096 to 0102 of JP-A-2019-124913, and this content is incorporated herein.

[0055] The above transparent conductive film is preferably used in film sensors of touch panels, electronic paper, dye-sensitized solar cells, touch sensors, etc. In particular, it is preferably used in applications that require flexibility, such as foldable displays and curved displays.

[0056] Specifically, the flat molded body and the multilayer body of the present invention can be used in parts of electric and electronic devices, OA devices, information terminal devices, machine parts, home appliances, vehicle parts, building members, various containers, leisure goods and sundries, lighting devices, etc., and parts of various household electric products, etc. For electric and electronic devices, for example, personal computers, game machines, television receivers, display devices such as liquid crystal display devices and plasma display devices, printers, copier, scanner, fax, electronic notebooks and PDAs, electronic desktop calculators, electronic dictionaries, cameras, video cameras, mobile phones, smartphones, tablets, battery packs, drives and reading devices for recording media, mice, numeric keypads, CD players, MD players, portable radio and audio players, etc. can be mentioned. In addition, it can be preferably used in fields such as electric signboards, liquid crystal backlights, lighting displays, traffic signs, signboards, screens, automotive parts such as reflectors and meter parts, toys, and ornaments.

Examples

[0057] The present invention will be described in more detail with reference to the following examples. The materials, amounts used, ratios, processing details, 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.

[0058] [Raw materials] · Bisphenol AP type polycarbonate (A1) Aromatic polycarbonate obtained by an interfacial polymerization method using bisphenol AP as a starting material (manufactured by Mitsubishi Gas Chemical Company, FPC-0220, viscosity average molecular weight 20,200, glass transition temperature 184 °C)

[0059] · Bisphenol A type polycarbonate (B1) Aromatic polycarbonate obtained by an interfacial polymerization method using bisphenol A as a starting material (manufactured by Mitsubishi Engineering-Plastics Corporation, H-4000F, viscosity average molecular weight 16,000, glass transition temperature 143 °C) (B2) Aromatic polycarbonate obtained by an interfacial polymerization method using bisphenol A as a starting material (manufactured by Mitsubishi Engineering-Plastics Corporation, H-7000F, viscosity average molecular weight 14,000, glass transition temperature 141 °C) (B3) Aromatic polycarbonate obtained by an interfacial polymerization method using bisphenol A as a starting material (manufactured by Mitsubishi Engineering-Plastics Corporation, E-2000F, viscosity average molecular weight 27,000, glass transition temperature 151 °C) (B4) Aromatic polycarbonate obtained by an interfacial polymerization method using bisphenol A as a starting material (manufactured by Mitsubishi Engineering-Plastics Corporation, K-4000F, viscosity average molecular weight 40,000, glass transition temperature 154 °C) (B5) Aromatic polycarbonate obtained by an interfacial polymerization method using bisphenol A as a starting material (manufactured by Mitsubishi Engineering-Plastics Corporation, S-3000F, viscosity average molecular weight 21,000, glass transition temperature 148 °C)

[0060] · Antioxidant (C1) 3,9-Bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane (Semi-hindered phenolic antioxidant, manufactured by ADEKA Corporation, Adeka Stab AO-80) (C2) Bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite (Phosphorus-based antioxidant, manufactured by ADEKA Corporation, Adeka Stab PEP-36)

[0061] · Release agent (D1) Glycerol monostearate (manufactured by Riken Vitamin Co., Ltd., Rikemal S-100A)

[0062] Example 1 <Manufacture of pellets> Each of the components described above was weighed so as to have the addition amounts described in Table 1 or Table 2. The compounding amounts of each component described in Table 1 or Table 2 are shown in parts by mass. Then, after mixing for 15 minutes in a tumbler, it was melt-kneaded at a cylinder temperature of 300 °C using a twin-screw extruder with a vent (TEX30α manufactured by Japan Steel Works, Ltd.) having a screw diameter of 32 mm, and pellets were obtained by strand cutting.

[0063] <Manufacture of film (flat-shaped molded body)> Using the pellets obtained above, a film (flat-shaped molded body) was manufactured by the following method. The pellets obtained above were extruded in a molten state using a T-die melt extruder consisting of a twin-screw extruder with a vent (TEX30α, manufactured by Japan Steel Works, Ltd.) having a barrel diameter of 32 mm and an L / D of the screw of 31.5, under the conditions of a discharge rate of 10 Kg / h and a screw rotation speed of 150 rpm, crimped between a first roll and a second roll, and then cooled and solidified to produce a film (flat-shaped molded body). The cylinder and T-die temperatures were set at 300 °C. Finally, the thickness (unit: μm) of the obtained film (flat-shaped molded body) was adjusted by changing the roll speeds of the first roll and the second roll so as to obtain the values described in Table 1 or Table 2. Details of the first roll and the second roll used are as follows. First roll: Silicone rubber roll (IT68S-MCG) manufactured by Mochida Shoko Co., Ltd. Dimensions: Outer diameter 260mm x width 600mm Roll temperature: 50℃ Second roll: Mirror-finished rigid metal roll (surface: hard chrome treatment) Core dimensions: outer diameter 250mm x width 600mm Roll temperature: 140℃

[0064] <Measurement of glass transition temperature> The glass transition temperature of the film (flat molded product) obtained above or the raw material polycarbonate was measured as follows: The film (flat molded product) was cut with scissors and measured. About 10 mg of the above sample was subjected to two cycles of heating and cooling according to the measurement conditions of DSC (differential scanning calorimetry) described below, and the glass transition temperature during the second heating cycle was measured. The intersection point of a straight line extending the baseline on the low temperature side to the high temperature side and a tangent to the inflection point was determined as the starting glass transition temperature, the intersection point of a straight line extending the baseline on the high temperature side to the low temperature side and a tangent to the inflection point was determined as the ending glass transition temperature, and the midpoint between the starting glass transition temperature and the ending glass transition temperature was determined as the glass transition temperature (unit: ° C.) in the present invention. Measurement start temperature: 30℃ Heating rate: 10℃ / min Achieved temperature: 250℃ Cooling rate: 20℃ / min The measurement was performed using a differential scanning calorimeter (DSC, Hitachi High-Tech Science Corporation, "DSC7020").

[0065] <Film processability> A film (flat plate-shaped molded product) was produced from the pellets. If it was possible to extrude, it was indicated as A, and if it was not possible to extrude due to too high a melt viscosity, it was indicated as B.

[0066] <Measurement of photoelastic coefficient> The film (flat-shaped molded body) obtained above was placed in an environment of 23°C and 50% relative humidity, and using an ellipsometer, while applying a stress load (0 to 720 gf) in the flow direction during film formation to the film (flat-shaped molded body), the in-plane retardation (Re) value of the film (flat-shaped molded body) was measured at a wavelength of 633 nm. Then, the photoelastic coefficient was calculated from the slope of stress and Re. In the table, the values multiplied by 10 -12 times are shown in the unit of m 2 / N. As the ellipsometer, Ellipsometer M-220 manufactured by JASCO Corporation was used.

[0067] <Measurement of haze> For the film (flat-shaped molded body) obtained above, using a haze meter, the haze (unit: %) was measured under the conditions of a D65 light source and a 10° field of view. As the haze meter, “HM-150” manufactured by Murakami Color Research Laboratory was used.

[0068] <Light leakage> In order to more clearly reproduce the optical defect that occurs when the flat-shaped molded body is bent, the evaluation was performed as “light leakage” shown below. The film (flat-shaped molded body) obtained above was cut into A4 size and wound into a cylindrical shape with a diameter of 30 mm with the short side as the axis to obtain a sample. As shown in Fig. 2, in front of the surface light source 21, two polarizing sheets 22 and 24 were arranged such that their polarization axes were orthogonal to each other. Then, a cylindrical sample 23 was placed between the polarizing sheets 22 and 24, and light leakage was visually confirmed. When birefringence does not occur in the cylindrical sample 23 installed between the polarizing sheet 22 and the polarizing sheet 24, the light polarized in a specific direction by the polarizing sheet 22 is blocked by the polarizing sheet 24, so no light passes through to the observation side. On the other hand, when birefringence occurs in the cylindrical sample 23, the light polarized in a specific direction by the polarizing sheet 22 returns to the unpolarized state, so part of the light passes through the polarizing sheet 24. That is, it is observed as light leakage. The test was conducted by 5 experts and judged by a majority vote. A: No light leakage occurs B: Slight light leakage occurs (not applicable to either A or C) C: Light leakage occurs

[0069] <Flexural resistance> The film (flat-shaped molded body) obtained above was cut into a size of 75×25 mm, and in accordance with JIS C5016, a flexural resistance test was conducted using an FPC bending tester at a bending surface curvature radius of 1.5 mm. In this flexural resistance test, the presence or absence of breakage of the test sample after 200,000 bending tests was visually evaluated and judged according to the following criteria. As the FPC bending tester, the "No. 306 FPC Bending Tester" (trade name) manufactured by Yasuda Seiki Seisakusho was used. The test was carried out by 5 experts and judged by a majority vote. A: No breakage B: Breakage occurred

[0070] <Heat shrinkage rate> Regarding any three locations in the film (flat-shaped molded body) obtained above, square samples with a width of 150 mm in the width direction and 150 mm in the flow direction were cut out. For the said samples, punctuation marks were marked at intervals of approximately 100 mm in the width direction and the flow direction of the film (flat-shaped molded body) in an atmosphere of 23°C and a relative humidity of 50%. After measuring the intervals using a vernier caliper, they were heat-treated in a constant temperature bath at 160°C for 30 minutes. After taking them out from the constant temperature bath and allowing them to stand for 60 minutes in an atmosphere of 23°C and a relative humidity of 50%, the intervals between the above punctuation marks were measured with a vernier caliper in an atmosphere of 23°C and a relative humidity of 50%. The heat shrinkage rate was calculated by the following formula, and the average value of the three locations was taken as the heat shrinkage rate in the width direction and the flow direction of the film (flat-shaped molded body). Heat shrinkage rate (%) = [((Dimensions before heat treatment) - (Dimensions after heat treatment)) / (Dimensions before heat treatment)] × 100 Note that the flow direction refers to the extrusion direction in the case of extrusion molding and the casting direction in the case of casting. The width direction refers to the direction perpendicular to the flow direction.

[0071] Examples 2 to 5, Comparative Examples 1 to 4 In Example 1, as shown in Table 1 or Table 2, the formulation of each component of the flat-shaped molded body was changed, and the rest was carried out in the same manner.

[0072] Comparative Example 5 In Example 1, as shown in Table 1 or Table 2, the formulation of each component of the flat-shaped molded body was changed, and further, in the production of the film (flat-shaped molded body), the following changes were made, and the rest was carried out in the same manner. · Second roll: Embossing roll with an arithmetic mean roughness of 2.4 μm Mandrel dimensions: Outer diameter 250 mm × width 600 mm Roll temperature: 140 °C In Comparative Example 5, due to the use of an embossing roll, the haze of the film (flat-shaped molded body) was high and it could not be used as an optical film. Therefore, evaluations of light leakage, flex resistance, and heat shrinkage rate were not performed.

[0073] Comparative Example 6 In Example 1, as shown in Table 1 or Table 2, the formulation of each component of the flat-shaped molded body was changed, and the rest was carried out in the same manner. In Comparative Example 6, the melt viscosity was too high to be processed into a film.

[0074]

Table 1

Table 2

Explanation of symbols

[0075] 1 Transparent conductive layer 2 Refractive index adjustment layer 3 Curable resin layer 4 Flat-shaped molded body 5 Protective film 21 Surface light source 22 Polarizing sheet 23 Cylindrical sample 24 Polarizing sheet

Claims

1. A flat molded article containing a bisphenol AP type polycarbonate having a glass transition temperature of 180°C or higher, The photoelastic coefficient is 85×10 －１２ m ２ / N or less, the thickness is 75 μm or less, and the haze is 2.0% or less, wherein the proportion of the structural unit represented by formula (A-1) in the bisphenol AP type polycarbonate is more than 90 mol% in all the structural units excluding the end groups, A flat molded article for use as a substrate of a transparent conductive film. 【Chemical 1】 (In formula (A-1), R1 to R4 each independently represent a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 9 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aralkyl group having 7 to 17 carbon atoms. l represents an integer of 0 to 5. m and n each independently represent an integer of 0 to 4. * in the formula represents the bonding position with other sites.)

2. Further containing a bisphenol A type polycarbonate, The flat molded article according to claim 1, wherein the proportion of the bisphenol AP type polycarbonate among the polycarbonates contained in the flat molded article is 15% by mass or more and 90% by mass or less.

3. The flat molded article according to claim 1 or 2, wherein the glass transition temperature of the flat molded article is 154°C or higher.

4. The flat molded article according to any one of claims 1 to 3, further containing an antioxidant.

5. The flat molded article according to any one of claims 1 to 4, further containing a release agent.

6. Cut into a size of 75×25 mm, and when a bending test is performed using an FPC bending tester in accordance with JIS C5016 with a curvature radius of the bending surface of 1.5 mm and a bending number of 200,000 times, it does not break. The flat molded article according to any one of claims 1 to 5.

7. A multilayer body having the flat molded article according to any one of claims 1 to 6.

8. The multilayer body according to claim 7, having a curable resin layer on one or both surfaces of the flat molded article.

9. The multilayer body according to claim 7 or 8, having a refractive index adjustment layer on one or both surfaces of the flat molded article.

10. The multilayer body according to any one of claims 7 to 9, having a protective film on one or both surfaces of the flat molded article.

11. The multilayer body according to any one of claims 7 to 10, having a transparent conductive layer on the flat molded article.

12. The multilayer body according to claim 11, wherein the transparent conductive layer contains one or more of ATO (antimony-doped indium oxide), FTO (fluorine-doped tin oxide), AZO (aluminum-doped zinc oxide), GZO (gallium-doped zinc oxide), ITO (indium tin composite oxide), Ag, Cu, Au, and carbon nanotubes.

13. The multilayer body according to claim 11 or 12, which is a transparent conductive film.

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