JP2019020722A - Aromatic nitrogen-containing polymer film and display member - Google Patents

Abstract

To provide an aromatic nitrogen-containing polymer film that has excellent flexibility and can reduce an interference color caused by polarization, and a display member.SOLUTION: An aromatic nitrogen-containing polymer film has a thickness of 10 to 90 μm and a front phase difference with respect to incident light with a wavelength of 550 nm of 1,000 to 30,000 nm.SELECTED DRAWING: None

Description

  The present invention relates to an aromatic nitrogen-containing polymer film and a display member, and particularly to an aromatic nitrogen-containing polymer film and a display member that can be suitably used as a transparent film for a flexible display.

  In recent years, a flexible display that can be folded and rolled has been developed in earnest from the viewpoint of portability and freedom of design. Such a display requires a polymer film that replaces glass in order to prevent bendability, weight reduction, thinning, and cracking due to impact.

  By the way, a polarizing plate is often disposed on the front side of the flexible display for the purpose of suppressing external light reflection and improving visibility. Therefore, when the display screen is viewed through polarized sunglasses or the like, an interference color (so-called rainbow unevenness) may occur between the polarizing plate / polymer film / polarized sunglasses due to the phase difference of the polymer film. This interference color is most likely to occur when the polarizing axes of the polarizing plate and the polarizing sunglasses are orthogonal.

  For example, Patent Documents 1 and 2 propose to use a λ / 4 retardation plate whose front phase difference is controlled to ¼ of the wavelength. The linearly polarized light that has passed through the polarizing plate is converted to circularly polarized light by passing through a λ / 4 retardation plate arranged at 45 degrees with respect to the transmission axis, so that it is suppressed from being orthogonal to the transmission axis of polarized sunglasses. , Visibility improvement effect can be expected.

  For example, Patent Document 3 proposes to arrange an oriented polycarbonate film or oriented polyester film having a front phase difference of 3,000 to 30,000 nm on the viewing side of the polarizing plate. It discloses that the long axis of elliptically polarized light is dispersed in various directions by passing through the film, and coloring can be suppressed.

JP 2005-352068 A JP2013-129852A JP2011-107198A

  However, the λ / 4 retardation plate of Patent Documents 1 and 2 is only adjusted for light of a specific wavelength, and light of other wavelengths is elliptically polarized, which leads to coloring of the screen. Even when the front phase difference is adjusted, interference occurs due to the phase difference in the oblique direction in the observation from an oblique direction, and coloring of the screen becomes a problem.

  In Patent Document 3, a polycarbonate film or a polyester film that is strongly oriented by uniaxial stretching is used. In order to obtain a target retardation, a film thickness of a certain level or more is required. The film has a problem in application to a flexible display because of its chemical structure and insufficient bending resistance at low temperatures. Even in this method, coloring is a problem when observed from an oblique direction.

  An object of this invention is to provide the aromatic nitrogen-containing polymer film and display member which are excellent in bending resistance, and eliminate the interference color by polarized light.

  In order to achieve the above object, the present invention is characterized by the following.

  An aromatic nitrogen-containing polymer film having a thickness of 10 to 90 μm and a front phase difference of 1,000 to 30,000 nm with respect to incident light having a wavelength of 550 nm.

  ADVANTAGE OF THE INVENTION According to this invention, the film which is excellent in bending resistance and can reduce the interference color by polarization | polarized-light by having a high phase difference although it is a thin film can be provided. Therefore, the film of the present invention can be suitably used particularly as a transparent film for flexible displays.

  The film of the present invention is composed of an aromatic nitrogen-containing polymer. Here, the aromatic nitrogen-containing polymer means a polymer having an aromatic ring and a nitrogen atom in the main chain. Examples of such polymers include aromatic polyamide (aramid), aromatic polyimide, aromatic polyamideimide, aromatic polyetherimide, and copolymers thereof.

  The film of this invention contains 51-100 mass% of said aromatic nitrogen-containing polymer with respect to the whole film (however, in the case of the aspect where the curable resin mentioned later is laminated | stacked, the said cured layer is excluded). Is preferred. More preferably, it is 80-100 mass%.

More preferably, the aromatic nitrogen-containing polymer constituting the film of the present invention preferably has a structural unit represented by any one of the following chemical formulas (I) to (IV).
Chemical formula (I):

R ¹ and R ² are —H, an aliphatic group having 1 to 5 carbon atoms, —CF ₃ , —CCl ₃ , —OH, —F, —Cl, —Br, —OCH ₃ , a silyl group, or an aromatic ring. Is a group containing _Preferably, -CF 3, a group containing -F, -Cl, or an aromatic ring.
Chemical formula (II):

R ³ is a group containing Si, a group containing P, a group containing S, a halogenated hydrocarbon group, a group containing an aromatic ring, or a group containing an ether bond (however, a structure having these groups in the molecule) Units may be mixed). A group containing Si, a halogenated hydrocarbon group, a group containing an aromatic ring, or a group containing an ether bond is preferable.
Chemical formula (III):

R ⁴ is an arbitrary group. Although not particularly limited, —H, —Cl, and —F are preferable.
Chemical formula (IV):

R ⁵ is an arbitrary aromatic group or an arbitrary alicyclic group. Although not particularly limited, phenyl, biphenyl, cyclohexane, and decalin are more preferable.

Among the above, the structural unit represented by the following chemical formula (V) has a particularly high in-plane orientation and easily obtains a high retardation within the range of the present invention. It is particularly preferable to have it.
Chemical formula (V):

R ⁶ is an arbitrary group. Although not particularly limited, —H, —Cl, and —F are preferable.

  The structural unit represented by the chemical formula (V) is preferably 20 to 100 mol% of the aromatic nitrogen-containing polymer constituting the film of the present invention. More preferably, it is 50-100 mol%, More preferably, it is 80-100 mol%.

  When it is necessary to identify the chemical structure and composition ratio of the aromatic nitrogen-containing polymer of the present invention, nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), mass spectrometry (MS), etc. Analysis can be performed in combination.

  The thickness of the film of the present invention is 10 to 90 μm. When the thickness is smaller than 10 μm, the handling property is deteriorated, the phase difference is small, and interference colors due to polarized light are easily generated. On the other hand, if the thickness exceeds 90 μm, the bending resistance may decrease. The thickness of the film is more preferably 10 to 55 μm, and still more preferably 15 to 35 μm, from the viewpoint of achieving both retardation and bending resistance. In addition, if it is in the said thickness range, you may bond and use the same kind or different kind | species film.

  The film of the present invention is characterized in that the front phase difference with respect to incident light having a wavelength of 550 nm is 1,000 to 30,000 nm. The front phase difference is more preferably 2,000 to 30,000 nm, and still more preferably 3,000 to 30,000 nm. Here, the front phase difference is measured by measuring the in-plane refractive index of the film, Nx is the refractive index in the direction in which the refractive index is maximum (that is, the slow axis direction), and the direction is orthogonal to the direction (that is, the fast axis direction). When the refractive index is Ny and the thickness of the film is d (nm), it is defined as (Nx−Ny) × d. By setting the front phase difference to 1,000 nm or more, it is possible to suppress interference colors due to polarized light when observed from the front. When the front phase difference is less than 1,000 nm, an interference color due to polarized light is generated, and visibility may be lowered when used for a display. In order to set the front retardation to 1,000 nm or more within the thickness range of the film of the present invention, it is preferable to produce a film under the conditions described later using a polymer having a high refractive index and high orientation. Examples of such a polymer include use of a polymer containing a structural unit represented by any one of the aforementioned chemical formulas (I) to (IV). Among the above, it is particularly preferable to have the structural unit represented by the chemical formula (V) shown above.

  In the film of the present invention, when the slow axis and the fast axis are inclined by 50 degrees with respect to the inclined central axis, the oblique phase difference with respect to incident light having a wavelength of 550 nm is 1,000 to 50,000 nm. Is preferred. The oblique direction phase difference is more preferably 2,000 to 50,000 nm, and still more preferably 3,000 to 50,000 nm.

  Here, the slow axis is the direction in which the refractive index becomes maximum in the film plane, and the fast axis is the direction orthogonal to the slow axis. Further, the oblique phase difference when the slow axis is tilted by 50 degrees with the slow axis as the tilt center axis is the refractive index in the slow axis direction when the film is tilted by 50 degrees with the slow axis as the tilt center axis. 50), where the refractive index in the direction perpendicular to the slow axis is Nzx (50) and the film thickness is d (nm), it is defined by | Nx (50) −Nzx (50) | × d, The oblique phase difference when the axis is tilted 50 degrees with the tilt axis as the tilt center axis is the refractive index in the fast axis direction Ny (50) when the fast axis is tilted 50 degrees with the tilt axis as the tilt center axis. Is defined as | Ny (50) −Nzy (50) | × d, where Nzy (50) is the refractive index in the direction perpendicular to the vertical axis and d (nm) is the film thickness.

  By setting both the oblique phase difference and the oblique phase difference with respect to the incident light having a wavelength of 550 nm to 1,000 nm or more, interference color due to polarized light can be suppressed even in oblique observation. If any one of the oblique phase differences is less than 1,000 nm, an interference color due to polarized light is generated at the time of observation from an oblique direction, and the visibility may be lowered when used for a display.

  In the thickness range of the film of the present invention, in order to make any of the retardations in the oblique direction 1,000 nm or more, a polymer having a high refractive index and high orientation, particularly high in-plane orientation, is used under the conditions described below. It is preferable to produce a film. Examples of such a polymer include use of a polymer containing a structural unit represented by any one of the aforementioned chemical formulas (I) to (IV). Among the above, it is particularly preferable to have the structural unit represented by the chemical formula (V) shown above.

  The film of the present invention preferably has a glass transition temperature (Tg) of 250 to 500 ° C. More preferably, it is 270-500 degreeC, More preferably, it is 300-500 degreeC. The glass transition temperature is determined from the inflection point of the storage elastic modulus by dynamic viscoelasticity measurement (DMA) based on ASTM E1640-13. When the glass transition temperature is less than 250 ° C., the bending resistance at low temperature is low, and when it is repeatedly folded in an environment of 0 ° C. or less, breakage or deformation may occur. In addition, deformation or cracking may occur when a conductive layer, a thin film transistor, a barrier layer, an antireflection layer, a decorative printing layer, or the like is formed on the film. In order to set the glass transition temperature to 250 ° C. or higher, it is preferable to use the above aromatic nitrogen-containing polymer as the polymer. More preferably, it contains an aromatic polyamide, an aromatic polyimide, or an aromatic polyamideimide, and more preferably a polymer containing a structural unit represented by any one of the aforementioned chemical formulas (I) to (IV) Is to use.

  The film of the present invention preferably has a Young's modulus in at least one direction of 5.0 to 20.0 GPa. More preferably, it is 6.0-20.0 GPa, More preferably, it is 8.0-20.0 GPa. When the Young's modulus in any direction is less than 5.0 GPa, the rigidity and surface hardness of the film are low, and particularly when used for the front film of a display, scratches and dents are easily formed. Moreover, the handling property of a film may deteriorate. In order to make the Young's modulus in at least one direction within the above range, it is preferable to use the above-described aromatic nitrogen-containing polymer as the polymer. In particular, it is more preferable to have the structural unit represented by the chemical formula (V) because the molecular chain has high rigidity. Moreover, it is preferable to manufacture a film on the conditions mentioned later.

  The film of the present invention preferably has a light transmittance of 80 to 100% in incident light having a wavelength of 450 nm. By setting the light transmittance at a wavelength of 450 nm to 80% or more, a highly transparent and small colored film can be obtained and can be suitably used for a display or the like. More preferably, it is 85% or more. When the light transmittance at a wavelength of 450 nm is less than 80%, the turbidity and coloring of the film are large, and the visibility of the screen may be lowered when used for a display. In order to set the light transmittance at a wavelength of 450 nm to 80% or more, it is effective to make the polymer structure less susceptible to charge transfer within or between molecules, in addition to keeping the amount of metal foreign matter in the raw material small. This suppresses absorption of visible light, particularly in the low wavelength region. As such a polymer structure, use of a polymer containing a structural unit represented by any one of the aforementioned chemical formulas (I) to (IV) can be mentioned. Among the above, it is particularly preferable to have the structural unit represented by the chemical formula (V) shown above.

  The film of the present invention preferably has a yellowness index (YI) of 0.1 to 5.0. When the degree of yellowness (YI) exceeds 5.0, the color of the film is large, and when used for a display or the like, the visibility may be lowered, for example, the screen becomes more yellowish. Since visibility improves more, it is more preferable that yellowness (YI) is 0.1-4.0, and it is still more preferable that it is 0.1-3.5. In order to reduce the yellowness (YI) to 0.1 to 5.0, in addition to suppressing the amount of metal foreign matter in the raw material, it is effective to have a polymer structure in which charge transfer within a molecule or between molecules is unlikely to occur. It is. This suppresses absorption of visible light, particularly in the low wavelength region. As such a polymer structure, use of a polymer containing a structural unit represented by any one of the aforementioned chemical formulas (I) to (IV) can be mentioned.

  The film of the present invention preferably has a haze of 0.1 to 3.0%. When the haze is larger than 3.0%, the turbidity of the film is large, and when used for a display or a transparent substrate, the visibility and brightness may be lowered. The haze is more preferably 0.1 to 2.0%, and further preferably 0.1 to 1.0%. In order to reduce the haze to 0.1 to 3.0%, it is effective to reduce foreign matter in the film to reduce internal haze, smooth the film surface, and reduce irregular reflection (external haze) on the surface. It is.

  The aromatic nitrogen-containing polymer film of the present invention may be a laminated film in which a cured layer containing a curable resin is laminated on one side or both sides.

  Examples of the curable resin contained in the cured layer include a thermosetting resin, an ultraviolet curable resin, a hydrolysis / condensation resin, and the like, and more specifically, an organic silicone type, a polyol type, a melamine type, and an epoxy type. Resins such as polyfunctional acrylates, urethanes, isocyanates, organic inorganic hybrids such as alkoxysilane compounds that are composites of organic and inorganic materials, and silsesquioxanes having curable functional groups It is done. More preferred are epoxy-based, polyfunctional acrylate-based, organic-inorganic hybrid-based, and silsesquioxane-based resins.

The hardened layer may contain particles. Here, the particles may be either inorganic particles or organic particles, but it is preferable to contain inorganic particles because high hardness is easily obtained. The inorganic particles are not particularly limited, and examples thereof include metal and metalloid oxides, silicides, nitrides, borides, chlorides, and carbonates. More specifically, silica (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zinc oxide (ZnO), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), antimony oxide (Sb ₂ O ₃ ) and Examples thereof include indium tin oxide (In ₂ O ₃ ). Further, for the purpose of further improving the phase difference, needle-like particles such as strontium carbonate (SrCO ₃ ) may be contained. The particles may be subjected to a surface treatment. Surface treatment as used herein refers to introducing a compound onto the particle surface by chemical bonding (for example, covalent bonding, hydrogen bonding, ionic bonding) or adsorption (for example, physical adsorption, chemical adsorption).

  Moreover, a hardened layer is good also as two or more layers by a different structure about one side.

  The thickness of the cured layer is preferably 0.2 to 40.0 μm, more preferably 0.2 to 20.0 μm per side. If the thickness is less than 0.2 μm, the effect of improving the hardness may not be sufficiently obtained. On the other hand, when the thickness exceeds 40.0 μm, the bending resistance is lowered, and when the laminated film is bent, a crack (crack) may occur in the cured layer.

  Here, in the laminated film, when the interface between the aromatic nitrogen-containing polymer film and the cured layer is unclear and the thickness of each layer cannot be determined, the interface can be defined by the following method. First, regarding the cross section of the laminated film, elemental analysis is continuously performed in the thickness direction by combining a scanning electron microscope (SEM) and an energy dispersive X-ray analysis (EDX) apparatus. Based on the obtained analysis results, a line analysis diagram is obtained for each detected element with the vertical axis representing the detection intensity and the horizontal axis representing the measurement position in the thickness direction. The intersection when the line analysis diagrams of each element are overlapped is taken as the interface between the aromatic nitrogen-containing polymer film and the cured layer. In addition, since it is preferable to determine the element species suitable for obtaining the intersection point according to the composition of the aromatic nitrogen-containing polymer film and the cured layer, it is appropriately determined from the analysis results. For example, silica particles are present in the cured layer. When included, it is preferable to analyze the nitrogen (N) element on the aromatic nitrogen-containing polymer film side and the silicon (Si) element on the hardened layer side.

  Hereinafter, although the aromatic polyamide and aromatic polyimide are demonstrated to the example about the manufacturing method of the aromatic nitrogen-containing polymer film of this invention, this invention is not limited to this.

  Various known methods can be used to obtain the aromatic polyamide. For example, when using a low temperature solution polymerization method using acid dichloride and diamine as raw materials, N-methylpyrrolidone, N, N-dimethylacetamide, A method of synthesis by solution polymerization in an aprotic organic polar solvent such as dimethylformamide or dimethyl sulfoxide, a method of synthesis by interfacial polymerization using an aqueous medium, or the like can be employed. Solution polymerization in an aprotic organic polar solvent is preferable because the molecular weight of the polymer can be easily controlled. When acid dichloride and diamine are used as raw materials, hydrogen chloride is by-produced as the polymerization reaction proceeds, but when neutralizing this, an inorganic neutralizing agent such as lithium carbonate, calcium carbonate, calcium hydroxide, Alternatively, an organic neutralizer such as ethylene oxide, propylene oxide, ammonia, triethylamine, triethanolamine, diethanolamine may be used.

  Various known methods can be used for obtaining the polyamic acid which is an aromatic polyimide or its precursor. For example, when polymerizing tetracarboxylic anhydride and aromatic diamine as raw materials, N- A method of synthesizing by solution polymerization in an aprotic organic polar solvent such as methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylformamide, dimethylsulfoxide and the like can be employed. As a method for ring-closing the synthesized aromatic polyamic acid to obtain an aromatic polyimide, a thermal ring closing method, a chemical ring closing method, a combination thereof, or the like is used. The thermal ring closure method is generally a method of ring closure by heat treatment of polyamic acid at about 100 to 500 ° C. On the other hand, the chemical ring closure method uses aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine and betapicoline as catalysts, and aliphatics such as acetic anhydride, propionic anhydride and butyric anhydride. In this method, the ring is closed using a dehydrating agent such as a carboxylic acid anhydride or an aromatic acid anhydride such as benzoic anhydride.

The logarithmic viscosity (η _inh ) of the polyamic acid which is an aromatic polyamide and an aromatic polyimide or a precursor thereof is preferably 2.5 to 7.0 dl / g, and preferably 3.5 to 7.0 dl / g. It is more preferable. When the logarithmic viscosity is less than 2.5 dl / g, the entanglement of polymer molecular chains is reduced, so that when the film is formed by the method described later, the film is easily broken or the target retardation is difficult to obtain. The front phase difference or the oblique phase difference may be less than 1,000 nm. Also, the bending resistance may be reduced. When the logarithmic viscosity is more than 7.0 dl / g, the solubility in a solvent and the film forming property may be lowered.

  In addition to the polymer, it is preferable to add a release agent to the film-forming stock solution of the present invention. By adding the release agent, when the film-like material is peeled from the support during the film-forming step described later, the peeling tension is reduced, and the stretching ratio in the longitudinal direction can be kept low. Thereby, when extending | stretching to the width direction in a post process, a polymer molecular chain can orientate more in the width direction and can make phase difference into the range of this invention. The release agent may be a known fluorine-based additive or amine-based additive, and is not particularly limited, and examples thereof include polytetrafluoroethylene (PTFE) -based additives and ethanolamine-based additives. The addition amount of the release agent is preferably 0.1 to 20% by mass with respect to the polymer mass.

Further, the film-forming stock solution of the present invention may contain other inorganic substances, organic substances, or additives made of organic-inorganic hybrid materials for the purpose of surface formation, hardness improvement, refractive index control and the like. Examples of such additives include inorganic substances such as SiO ₂ , TiO ₂ , Al ₂ O ₃ , CaSO ₄ , BaSO ₄ , CaCO ₃ , carbon black, carbon nanotubes, fullerene, zeolite, and other metal fine powders. . Examples of the organic substance include, for example, particles made of an organic polymer such as crosslinked polyvinylbenzene, crosslinked acryl, crosslinked polystyrene, polyester particles, polyimide particles, polyamide particles, and fluororesin particles, or the surface is coated with the organic polymer. Inorganic particles that have been subjected to the above-described treatment are listed. Examples of the organic / inorganic hybrid material include alkoxysilane compounds.

  The film-forming stock solution prepared as described above is formed into a film by a so-called solution film-forming method. The solution casting method includes, for example, a drying process, a dry-wet process in which heat treatment is performed through a water-washing process in a wet bath, a dry process in which heat treatment is performed after the drying process, or after being introduced into the wet bath without performing the drying process. There is a wet method in which heat treatment is performed, and any method may be used to form a film. Here, a dry and wet method will be described as an example.

  When a film is formed by a dry-wet method, the film-forming stock solution is extruded from a die onto a support such as a drum, an endless belt, or a support film, and then dried until the film-like material has self-holding properties. The The drying temperature is usually in the range of 60 to 200 ° C.

  The film-like material after the drying step is peeled off from the support, but at this time, it is preferable to keep the peeling tension applied to the film-like material low. Thereby, the draw ratio of a longitudinal direction (MD) can be restrained low, and when it extends | stretches in the width direction (TD) at a post process, a polymer molecular chain becomes easier to orientate in the width direction. In order to keep the peel tension low, it is effective to add a fluorine-based additive or the like as a mold release agent to the film forming stock solution. The polymer concentration at the time of peeling the film-like material from the support is preferably 30 to 70% by mass, and more preferably 40 to 60% by mass. When the polymer concentration at the time of peeling is less than 30% by mass, the self-holding property is not sufficient, and tension may be applied at the time of peeling from the support, or two-layer peeling may occur and a film-like material may be left on the support. . When the polymer concentration at the time of peeling exceeds 70% by mass, peeling from the support may be difficult, or the film-like material may be devitrified and the haze of the final film may exceed 3.0%.

  The film-like material peeled from the support is introduced into a wet process, and desalting, de-additive, solvent removal, etc. are performed. The solvent for the wet process is generally aqueous, but may contain a small amount of an inorganic or organic solvent or an inorganic salt in addition to water. The solvent temperature is usually 5 to 90 ° C.

  When peeling the film-like material from the support and during a wet process, the draw ratio in the longitudinal direction is preferably 0.90 to 1.07. If the draw ratio in the longitudinal direction exceeds 1.07 times, the polymer molecular chain may be difficult to be uniaxially oriented in the width direction even if it is stretched in the width direction in a subsequent step. The longitudinal draw ratio is defined as a value obtained by dividing the stretched film length by the film length before peeling from the support.

  The film that has undergone the wet process is then introduced into a tenter or the like, and stretched in the width direction of the film along with heat treatment. Although the atmosphere of the heat treatment step may be an air atmosphere, an inert atmosphere such as nitrogen or argon is most preferable because yellowness (YI) can be further reduced. The temperature Ts (° C.) at the time of stretching in the width direction may be set within the temperature range of Tg-50 ≦ Ts ≦ Tg-20, assuming that the glass transition temperature of the polymer is Tg (° C.). It is effective in raising.

In order to set the front phase difference and the oblique phase difference within the scope of the present invention, assuming that the longitudinal stretching ratio in the entire film forming process is S _MD and the stretching ratio in the width direction is S _TD , S _TD / S _MD ≧ It is preferably 1.40, more preferably S _TD / S _MD ≧ 1.45, and even more preferably S _TD / S _MD ≧ 1.50. The stretching ratio in the width direction is defined as a value obtained by dividing the film width after stretching by the film width before stretching.

  Moreover, it is good also as a laminated | multilayer film which laminated | stacked the cured layer containing curable resin on the single side | surface or both surfaces of the aromatic nitrogen-containing polymer film of this invention formed into a film by the above method.

  Examples of the method for laminating the cured layer include a method in which a coating material made of a curable resin is applied on a film, followed by drying and curing. When two or more cured layers are laminated in different configurations, they may be formed one by one in the order of application, drying, and curing, or a plurality of coating agents may be applied simultaneously using a multilayer slit die or the like. It may be dried and cured.

  Examples of the application method include dip coating, roller coating, wire bar coating, gravure coating, and die coating. Further, examples of the drying method include heat transfer drying, hot air drying, drying by infrared irradiation, drying by microwave irradiation, and the like. Although not particularly limited, drying by hot air irradiation is preferable.

Examples of the curing method include thermal curing or curing by irradiating active energy rays such as electron beams and ultraviolet rays. In the case of thermosetting, it is preferable to cure at a temperature of 40 to 200 ° C, more preferably 80 to 200 ° C. In the case of curing by irradiation with ultraviolet rays or electron beams, it is preferable to lower the oxygen concentration in the atmosphere, and it is more preferable to cure in an inert gas atmosphere such as nitrogen or argon. If the oxygen concentration is high, curing may be insufficient. Examples of the ultraviolet lamp used when irradiating with ultraviolet rays include a discharge lamp method, a flash method, a laser method, and an electrodeless lamp method. When ultraviolet curing is performed using a high-pressure mercury lamp that is a discharge lamp method, the illuminance of ultraviolet rays is preferably 100 to 3,000 mW / cm ² , more preferably 200 to 2,000 mW / cm ² .

  The aromatic nitrogen-containing polymer film of the present invention is a display material, display material substrate, circuit board, optical waveguide substrate, semiconductor mounting substrate, transparent conductive film, retardation film, touch panel, capacitor, printer ribbon, acoustic diaphragm, solar It is preferably used in various applications such as batteries, optical recording media, base films for magnetic recording media, packaging materials, adhesive tapes, adhesive tapes, and decorative materials.

  Especially, since it has the outstanding bending resistance and optical characteristic, it can use suitably as a transparent film for flexible displays. In particular, when the aromatic nitrogen-containing polymer film of the present invention is disposed on the viewing side of the polarizing plate, the angle of the transmission axis of the polarizing plate coincides with the slow axis of the aromatic nitrogen-containing polymer film. This arrangement is preferable because it is easy to obtain the effect of eliminating interference colors caused by polarized light.

  The present invention will be described more specifically with reference to the following examples.

  The measurement method of physical properties and the evaluation method of effects in the present invention were performed according to the following methods.

(1) Logarithmic viscosity (η _inh )
The polymer was dissolved at a concentration of 0.5 g / dl in N-methyl-2-pyrrolidone (NMP) containing 2.5% by mass of lithium bromide, and the flow time was 30 ° C. using an Ubbelohde viscometer. Was measured. The flow time of the blank solution in which the polymer was not dissolved was also measured in the same manner, and the logarithmic viscosity (η _inh ) was calculated using the following formula.

η _inh (dl / g) = [ln (t / t ₀ )] / 0.5
t: Flow time of the polymer solution (second)
t ₀ : Flowing time of the blank solution (second)
(2) Thickness The thickness was calculated by observing the sample cross section using the following apparatus.

Cross-section preparation: electronic sample freezing apparatus MODEL: RM and rotary microtome MODEL: RM (manufactured by Japan Microtome Laboratories)
Observation apparatus: scanning electron microscope (FE-SEM) JSM-6700F type (manufactured by JEOL Ltd.)
Observation magnification: 3,000 times Observation mode: LEI mode Acceleration voltage: 3 kV
(3) Front phase difference with respect to incident light having a wavelength of 550 nm The front phase difference of the sample with respect to incident light having a wavelength of 550 nm and an incident angle of 0 degrees was measured using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments).

(4) Diagonal phase difference with respect to incident light having a wavelength of 550 nm Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Co., Ltd.), the oblique phase difference of the sample with respect to incident light having a wavelength of 550 nm and an incident angle of 50 degrees was measured. In addition, the inclination central axis of the incident angle was set to each of the slow axis and the fast axis of the sample.

(5) Glass transition temperature It calculated | required from the inflexion point of the storage elastic modulus (E ') by dynamic viscoelasticity measurement (DMA) based on ASTM E1640-13. DMA was performed with the following equipment and conditions.

Apparatus: Viscoelasticity measuring apparatus DMS6100 (manufactured by Seiko Instruments Inc.)
Measurement mode: Tensile mode Measurement frequency: 1 Hz
Temperature increase rate: 5 ° C / min Temperature range: 25 ° C to 400 ° C
Holding time: 2 minutes (6) Young's modulus A sample cut to a width of 10 mm and a length of 150 mm in the measurement direction was measured using a robot tensilon AMF / RTA-100 (manufactured by Orientec) with a distance between chucks of 50 mm and a tensile speed of 300 mm / The tensile test was performed under the conditions of minute, temperature of 23 ° C. and relative humidity of 65%, and obtained from the obtained load-elongation curve.

(7) Light transmittance in incident light having a wavelength of 450 nm The light transmittance at a wavelength of 450 nm was determined from the following equation using the following apparatus.

Apparatus: UV measuring instrument U-3410 (manufactured by Hitachi Instruments)
Wavelength range: 300 nm to 800 nm
Measurement speed: 120 nm / min Measurement mode: Transmission Light transmittance (%) = (Tr1 / Tr0) × 100
However, Tr1 is the intensity | strength of the light which passed the sample, Tr0 is the intensity | strength of the light which passed the air of the same distance except not passing a sample.

(8) Yellowness (YI)
Using a spectrocolorimeter (Nippon Denshoku Industries Co., Ltd.), the measurement was performed at a temperature of 23 ° C. and a humidity of 65% RH. The sample size was 40 mm × 50 mm and was measured in transmission mode.

(9) Haze It measured using the following apparatus.

Apparatus: Turbidimeter NDH5000 (Nippon Denshoku Industries Co., Ltd.)
Light source: White LED 5V3W (rated)
Light receiving element: Si photodiode with V (λ) filter Measurement light beam: φ14 mm (incident aperture φ25 mm)
Optical conditions: Compliant with JIS-K7136 (2000) (10) Observation of interference color by polarized light A polarizing plate / sample / polarizing plate were stacked in order on a white LED light source. Here, the transmission axes of the two polarizing plates were orthogonal (crossed Nicols), and the slow axis of the sample was arranged to coincide with the transmission axis of the polarizing plate on the light source side.

  With respect to the above, the presence or absence of interference colors was observed from the front and from each of 50 degrees oblique with the slow axis and the fast axis of the sample as the central axis of inclination, and the following criteria were used.

○: No interference color observed, good Δ: Some interference color was visually recognized, but within practical range ×: Interference color strongly observed, out of practical range (11) Low temperature bending resistance JIS-K5600-5 1 (1999) was used, and the temperature was measured at -20 ° C. under the following conditions.

Sample size: short side 50mm x long side 100mm
Sample installation: Installation so that the position of 50 mm in the long side direction is the folding line (cylindrical contact part) Cylindrical dimension: Diameter 2 mm
Folding frequency: 1 million times Folding speed: 1Hz
Judgment criteria: Samples were observed after a prescribed number of tests in each of the two directions when the slow axis direction and the fast axis direction were long sides, and judged according to the following criteria.

○: No occurrence of undulations, cracks, tears or breaks, good △: No waving was confirmed in any direction, but within practical range ×: Cracks, tears or breaks in any direction (12) Preparation of membrane-forming stock solution Polymer A: 2,2′-ditrifluoromethyl-4,4 as diamine to dehydrated N-methyl-2-pyrrolidone (NMP, manufactured by Mitsubishi Chemical Corporation) '-Diaminobiphenyl (TFMB, manufactured by Toray Fine Chemical Co., Ltd.) was dissolved in a nitrogen stream, and the liquid temperature was cooled to 8 ° C in an ice water bath. Then, in a state where the system was kept in an ice water bath under a nitrogen stream, 2-chloroterephthaloyl chloride (CTPC, manufactured by Nippon Light Metal Co., Ltd.) corresponding to 99 mol% with respect to the total amount of diamine was taken over 30 minutes. After adding the whole amount and stirring for about 2 hours, an aromatic polyamide (polymer A, η _inh = 4.5 dl / g) was polymerized. The obtained polymerization solution was neutralized with 97% by mole of lithium carbonate (Honjo Chemical Co.) corresponding to the total amount of acid chloride, and further 6% by mole of diethanolamine (DEA, Tokyo Chemical Industry Co., Ltd.) and 3 A fluorine-based additive “Zonyl” (manufactured by DuPont) corresponding to mol% was added and stirred to obtain a film-forming stock solution of polymer A having a polymer concentration of 10% by mass.

Polymer B: As raw material monomers, diamine is TFMB corresponding to 90 mol% and 4,4′-diaminodiphenyl ether (DPE, manufactured by Tokyo Chemical Industry Co., Ltd.) corresponding to 10 mol%, and acid chloride is diamine. Polymer A except that terephthaloyl chloride corresponding to 60 mol% (TPC, manufactured by Tokyo Chemical Industry Co., Ltd.) and isophthaloyl chloride corresponding to 39 mol% (IPC, manufactured by Tokyo Chemical Industry Co., Ltd.) are used with respect to the total amount. In the same manner as above, a film-forming stock solution of polymer B (η _inh = 4.5 dl / g) was obtained.

Polymer C: As a raw material monomer, diamine is 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane corresponding to 100 mol% with respect to the total amount of diamine, and acid chloride is 100 with respect to the total amount of diamine. A film-forming stock solution of polymer C (η _inh = 5.0 dl / g) was obtained in the same manner as polymer A except that TPC corresponding to mol% was used.

Polymer D: TFMB as a diamine was dissolved in dehydrated NMP at room temperature. Thereto, 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA, manufactured by Tokyo Chemical Industry Co., Ltd.) corresponding to 20 mol% and 1,2,3 corresponding to 20 mol% with respect to the total amount of diamine. , 4-cyclopentanetetracarboxylic dianhydride (CPDA, manufactured by Tokyo Chemical Industry Co., Ltd.) was added over 15 minutes, and stirring was performed for 1 hour. Next, TPC corresponding to 59 mol% with respect to the total amount of diamine was added over 15 minutes, and stirring was performed for 1 hour. Subsequently, pyridine and acetic anhydride (both manufactured by Tokyo Chemical Industry Co., Ltd.) corresponding to 80 mol% with respect to the total amount of diamine were added, and stirring was performed at 70 ° C. for 1 hour. Finally, DEA corresponding to 8 mol% and fluorinated additive “Zonyl” corresponding to 3 mol% with respect to the total amount of diamine were added and stirred for 15 minutes, whereby polymer D (η _inh = 3.5 dl / The film-forming stock solution of g) was obtained.

Polymer E: TFMB as a diamine was dissolved in dehydrated NMP at room temperature. Thereto, 6FDA corresponding to 70 mol% and CPDA corresponding to 29 mol% were added over 30 minutes with respect to the total amount of diamine, and stirring was performed for 2 hours. Next, pyridine and acetic anhydride corresponding to 200 mol% with respect to the total amount of diamine were added, and stirring was performed at 70 ° C. for 1 hour. Finally, DEA corresponding to 8 mol% with respect to the total amount of diamine and a fluorine-based additive “Zonyl” corresponding to 3 mol% are added and stirred for 15 minutes, whereby polymer E (η _inh = 3.5 dl / The film-forming stock solution of g) was obtained.

Example 1
A film-forming stock solution composed of polymer A was cast from a die onto a stainless steel endless belt in the form of a film. Next, the cast film was introduced into an oven chamber having a hot air temperature of 120 ° C., and the solvent was evaporated until the polymer concentration reached 50% by mass. Next, the film-like material was peeled off from the endless belt, and introduced into a water tank in which pure water of 40 ° C. was run, and desalting, de-additive, and solvent removal were performed. Here, in the process from casting to exiting the water tank, the film was stretched 1.02 times in the longitudinal direction. Finally, the film from the water tank was introduced into a 280 ° C. tenter and subjected to heat treatment, and stretched 1.50 times in the width direction (S _TD / S _MD = 1.47). Tables 1 and 2 show the film forming conditions and the physical properties of the obtained polymer A film.

(Example 2)
A film was obtained in the same manner as in Example 1 except that the casting thickness was changed and the final thickness was as shown in Table 1. The physical properties of the obtained film are shown in Tables 1 and 2.

(Example 3)
A film was obtained in the same manner as in Example 1 except that the film-forming stock solution and the film-forming conditions were changed as shown in Table 1. The physical properties of the obtained film are shown in Tables 1 and 2.

Example 4
A film was obtained in the same manner as in Example 1 except that the film-forming stock solution and the film-forming conditions were changed as shown in Table 1. The physical properties of the obtained film are shown in Tables 1 and 2.

(Example 5)
A film was obtained in the same manner as in Example 4 except that the casting thickness was changed and the final thickness was as shown in Table 1. The physical properties of the obtained film are shown in Tables 1 and 2.

(Example 6)
A film was obtained in the same manner as in Example 1 except that the film-forming stock solution and the film-forming conditions were as shown in Table 1, and the tenter temperature was changed to 340 ° C. The physical properties of the obtained film are shown in Tables 1 and 2.

(Example 7)
A film was obtained in the same manner as in Example 6 except that the casting thickness was changed and the final thickness was as shown in Table 1. The physical properties of the obtained film are shown in Tables 1 and 2.

(Example 8)
A film was obtained in the same manner as in Example 1 except that the film-forming stock solution and the film-forming conditions were as shown in Table 1, and the tenter temperature was changed to 340 ° C. The physical properties of the obtained film are shown in Tables 1 and 2.

Example 9
Two films obtained in the same manner as in Example 1 were bonded via an adhesive layer having a thickness of 5 μm made of an adhesive “Aronix” LCR0628A (manufactured by Toagosei Co., Ltd.) to obtain a film. The physical properties of the obtained film are shown in Tables 1 and 2.

(Comparative Example 1)
A film was obtained in the same manner as in Example 1 except that the film forming conditions were changed as shown in Table 1. The physical properties of the obtained film are shown in Tables 1 and 2. In addition, since no fluorine-based additive was added as a mold release agent in the preparation of a film-forming stock solution composed of polymer A, the film was stretched 1.10 times in the longitudinal direction as a result of the peeling tension required for peeling from the endless belt. It was done.

(Comparative Example 2)
A film was obtained in the same manner as in Comparative Example 1 except that the casting thickness was changed and the final thickness was as shown in Table 1. The physical properties of the obtained film are shown in Tables 1 and 2. In addition, since no fluorine-based additive was added as a mold release agent in the preparation of a film-forming stock solution composed of polymer A, the film was stretched 1.10 times in the longitudinal direction as a result of the peeling tension required for peeling from the endless belt. It was done.

Claims (8)

An aromatic nitrogen-containing polymer film having a thickness of 10 to 90 μm and a front phase difference of 1,000 to 30,000 nm with respect to incident light having a wavelength of 550 nm. 2. The oblique phase difference with respect to incident light having a wavelength of 550 nm when the slow axis and the fast axis are tilted by 50 degrees with respect to the tilt center axis is 1,000 to 50,000 nm. Aromatic nitrogen-containing polymer film. The aromatic nitrogen-containing polymer film according to claim 1 or 2, wherein the glass transition temperature is 250 to 500 ° C. The aromatic nitrogen-containing polymer film according to any one of claims 1 to 3, wherein Young's modulus in at least one direction is 5.0 to 20.0 GPa. The aromatic nitrogen-containing polymer film according to any one of claims 1 to 4, comprising at least one polymer selected from the group consisting of aromatic polyamide, aromatic polyimide, and aromatic polyamideimide. The aromatic nitrogen-containing polymer film according to any one of claims 1 to 5, comprising a polymer having a structural unit represented by any of the following chemical formulas (I) to (IV).
Chemical formula (I):

R ¹ and R ² are —H, an aliphatic group having 1 to 5 carbon atoms, —CF ₃ , —CCl ₃ , —OH, —F, —Cl, —Br, —OCH ₃ , a silyl group, or an aromatic ring. Is a group containing
Chemical formula (II):

R ³ is a group containing Si, a group containing P, a group containing S, a halogenated hydrocarbon group, a group containing an aromatic ring, or a group containing an ether bond (however, a structure having these groups in the molecule) Units may be mixed).
Chemical formula (III):

R ⁴ is an arbitrary group.
Chemical formula (IV):

R ⁵ is an arbitrary aromatic group or an arbitrary alicyclic group. The aromatic nitrogen-containing polymer film according to any one of claims 1 to 6, comprising a polymer having a structural unit represented by the following chemical formula (V).
Chemical formula (V):

R ⁶ is an arbitrary group. A display member having at least a polarizing plate and the aromatic nitrogen-containing polymer film according to any one of claims 1 to 7, wherein an angle between a transmission axis of the polarizing plate and a slow axis of the aromatic nitrogen-containing polymer film Is a display member in which the aromatic nitrogen-containing polymer film is disposed on the viewing side of the polarizing plate so that the two match.