CN111697093A - Flexible composite film and method for manufacturing the same - Google Patents

Abstract

The present application provides flexible composite films comprising a polymer layer and an anodic metal oxide film. The flexible composite film of the present invention can be used as a surface material in highly flexible displays, as a substrate material for fine pitch flexible copper clad laminates (FCCL), as a surface material for flexible solar cells, and the like.

Description

Flexible composite film and method of making the same

technical field

The present invention relates to a flexible composite film comprising an anodic metal oxide film.

Background technique

There is a growing demand for flexible devices that are as light and thin as paper. Polymer films have the advantages of excellent flexibility, high resistance to breakage, and the possibility of reducing manufacturing costs through roll-to-roll production. However, the insufficient scratch resistance of polymer films limits their applications as surface materials or substrate materials in highly flexible devices, such as cover sheets for flexible displays, fine-pitch flexible copper-clad laminates ( FCCL), and as a cover sheet for flexible solar cells.

A solution to the above-mentioned problems consists in surface coating and/or attaching at least one protective layer on the polymer film. Organic-based coatings such as applying polysiloxane coatings, acrylic coatings, etc. do provide improved scratch resistance. However, the long-term weatherability and heat resistance of the coated composite films are still less than ideal. It has been found that the application of such coating layers often results in increased haze of the polymer film. Instead, attaching protective layers of inorganic metal oxide films derived from aluminum or zirconium foils does improve surface mechanical properties as well as weather and heat resistance. Although composite films with protective metal oxide layers can be obtained by bonding a polymer film with an adhesive, delamination or cracks may occur after repeated bending or folding operations, so such composite films Not suitable for high flexibility applications.

To avoid the delamination problem, the metal oxide layer may be deposited by a vacuum deposition based process such as physical vapor deposition (PVD) or plasma enhanced chemical vapor deposition (PECVD). However, these vacuum deposition based processes are often time consuming and expensive.

SUMMARY OF THE INVENTION

The present invention provides a composite film comprising: a polymer layer and an anodic metal oxide film, wherein the anodic metal oxide film is derived from an anodized metal foil; the anodic metal oxide film has a nanostructure, the The nanostructure includes a dense layer and a porous layer having a plurality of nanopores; the porous layer of the anodic metal oxide film is embedded in the polymer layer; and, as measured according to the method of ASTM D522/D 522M-17, the composite The outer bend radius of the film is 1.5 mm or less, and the inner bend radius is 1.5 mm or less.

In one embodiment of the composite film of the present invention, the overall thickness of the composite film is in the range of about 5 μm to about 250 μm.

In another embodiment of the composite film of the present invention, the porous layer of the anodic metal oxide film has a thickness (T _p ) in the range of about 0.5 μm to about 7 μm, and the dense layer of the anodic metal oxide film The thickness (T _d ) is in the range of about 2 nm to about 300 nm.

In yet another embodiment of the composite membrane of the present invention, the porous layer of the anodic metal oxide membrane includes a plurality of nanopores, the nanopores have an average pore diameter (D _p ) of about 1 nm to about 250 nm, and an average pore spacing ( D _int ) is about 5 nm to about 500 nm, and the D _p /D _int ratio is in the range of 0.1 to 0.9.

In yet another embodiment of the composite film of the present invention, the metal foil is composed of aluminum, titanium, zirconium, and alloys thereof.

In yet another embodiment of the composite film of the present invention, the polymer layer comprises polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polyimide (PI), or a copolymer thereof.

In one embodiment of the composite film of the present invention, the composite film has a dielectric constant of 4 or less at 2.45 GHz, measured according to the IEC 61189-2-721 method.

In another embodiment of the composite film of the present invention, the composite film has a total light transmittance between 400 nm and 800 nm of about 80% or higher.

The present invention also provides a method for manufacturing the composite membrane of the present invention, comprising:

(i) providing an anodized metal foil and a polymer composition;

(ii) coating the polymer composition on an anodized surface of the anodized metal foil;

(iii) heating the product of step (ii) at a temperature ranging from about 50°C to about 500°C for 30 seconds to 6 hours to form a polymer layer;

(iv) optionally, removing an uncoated anodic metal oxide film, if present, in the product of step (iii) to expose the metal foil; and

(v) chemically or mechanically removing the metal foil and, if present, the uncoated anodic metal oxide film from the product of step (iii) or the product of step (iv);

in

the anodized metal foil includes a metal foil and at least one anodic metal oxide film grown on the surface of the metal foil by anodization;

the anodic metal oxide film has a nanostructure including a dense layer and a porous layer having a plurality of nanopores, and the dense layer of the anodic metal oxide film is in contact with the metal foil; and

The polymer composition comprises at least one polymer resin or a precursor thereof.

Description of drawings

1 is a cross-sectional view illustrating a composite membrane according to an embodiment of the present invention.

2 is a cross-sectional view illustrating the nanostructure of an anodized metal foil suitable for use in the composite film manufacturing method of the present invention.

Figure 3 illustrates one embodiment of a method for manufacturing a composite membrane according to the present invention.

Skilled artisans understand that objects in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the objects in the figures may be exaggerated relative to other objects to help improve understanding of the embodiments.

Detailed ways

If not indicated otherwise, all publications, patent applications, patents, and other references mentioned in this specification are expressly incorporated by reference in their entirety into this specification for all purposes as if fully disclosed herein.

If not indicated otherwise, all publications, patent applications, patents, and other references mentioned in this specification are expressly incorporated by reference in their entirety into this specification for all purposes as if fully disclosed herein.

All percentages, parts, ratios, etc. are by weight unless otherwise indicated.

As used in this specification, the term "prepared by" is synonymous with the term "comprising". As used in this specification, the terms "comprising", "including", "having", "containing" or any other variations thereof are intended to cover non-exclusive inclusions. For example, a composition, process, method, article or apparatus comprising a series of elements is not necessarily limited to those elements, but may include other elements not expressly listed or the components of such composition, process, method, article or apparatus. other inherent elements.

The conjunction "consisting of" excludes any unspecified element, step or ingredient. If in a claim, such a conjunction will enclose the claim to the recited material, except for impurities usually associated therewith. When the phrase "consisting of" appears in a clause in the characterizing part of a claim rather than immediately following the preamble, it is limited only to the elements listed in that clause; the other elements are not not excluded from the claims in their entirety.

The conjunction "consisting essentially of" is used to define a composition, method, or apparatus that includes materials, steps, features, components, or elements other than those literally discussed, provided that such additional The materials, steps, features, components or elements do not materially affect the basic and novel characteristics of the claimed invention. The term "consisting essentially of" is located in an intermediate range between "comprising" and "consisting of."

The term "comprising" includes embodiments encompassed by the terms "consisting essentially of" and "consisting of." Similarly, the term "consisting essentially of" includes embodiments encompassed by the term "consisting of."

When an amount, concentration or other value or parameter is given as a list of a range, preferred range or upper preferred value and lower preferred value, it should be understood that any pair of the upper range or preferred value and lower range or preferred value is specifically disclosed All ranges formed by values, whether or not ranges are disclosed individually. For example, when a range of "1-5" is recited, the disclosed range should be understood to include "1-4", "1-3", "1-2", "1-2 and 4-5", " 1-3 and 5" etc. When numerical ranges are recited in this specification, unless otherwise indicated, the ranges are intended to include the endpoints of the range as well as all integers and fractions within the range.

When the term "about" is used to describe an endpoint of a value or range, the disclosure should be understood to include the particular value or endpoint referred to.

Furthermore, unless expressly stated to the contrary, "or" refers to an inclusive "or" rather than an exclusive "or." For example, any of the following satisfies the condition that A "or" B: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and Both A and B are true (exist).

Mol % refers to mole percent.

In the specification and/or claims of the present invention, the term "homopolymer" refers to a polymer obtained by the polymerization of one repeating unit; the term "copolymer" refers to a polymer comprising two or more comonomers copolymerized The resulting polymer of copolymerized units.

As used in this specification, the terms "a" and "an" include the concepts of "at least one" and "one or more than one".

A number of aspects and embodiments have been described above, and these aspects and embodiments are exemplary only and not restrictive. After reading this specification, those skilled in the art understand that other aspects and embodiments are possible without departing from the scope of the invention. Other features and advantages of the present invention will be apparent from the following detailed description and claims.

1, the present application discloses a composite film 100 comprising: a polymer layer 10 and an anodic metal oxide film 20, wherein the anodic metal oxide film 20 is derived from an anodized metal foil; the anodic metal oxide The membrane 20 has a nanostructure including a dense layer 21 and a porous layer 22 having a plurality of nanopores 23 . The porous layer 22 of the anodic metal oxide film 20 is embedded in the polymer layer 10 .

anodized metal foil

Anodic metal oxide films suitable for use in the present application are grown on the surface of the metal foil by anodization. Anodizing involves immersing a metal substrate as an anode in an acid bath and applying an electrical bias. This process oxidizes the anode and creates a plurality of nanopores that are vertically oriented on the surface of the metal substrate. As shown in FIG. 2, the anodized metal foil 200 thus formed comprises an anodic metal oxide film 20 and the remaining unoxidized metal foil 30, wherein the anodic metal oxide film is composed of a dense layer 21 with a thickness marked _Td and a Each nanopore 23 is composed of a porous layer 22 whose thickness is marked as T _p , and this dense layer 21 is in contact with said non-oxidized metal foil 30 .

The thickness of the anodic metal oxide film and the size of the nanopores can be controlled by changing the conditions and time of anodization. To control the pore structure of the anodic metal oxide film, the anodization process can be repeated one or more times. It should be noted that the metal foil can be anodized first on one surface (ie, masking the other side with a protective film), or anodized on the surfaces on both sides. Since 1st anodized metal oxide films usually have a less ordered pore structure and a rough, matte appearance, they can be chemically stripped with an acid-containing aqueous solution and then subjected to a 2nd pass or repeated as needed Anodization is performed to obtain an anodic metal oxide film with a porous layer with uniformly distributed nanopores and a smooth, shiny appearance.

Anodic metal oxide films suitable for use in the present invention are derived from metal foils by anodization. Exemplary metal foils include, but are not limited to, aluminum (Al), titanium (Ti), zirconium (Zr), and alloys thereof.

In one embodiment, the anodic metal oxide film used herein is an anodic aluminum oxide (AAO) film. AAO films can be prepared by using an aluminum substrate (eg, aluminum foil or aluminum alloys (such as Al-Fe-Si-Zn-Cu-Mn-Mg)) as the anode and non-reaction in the electrolyte as a conductive cathode Materials such as lead, platinum, or graphite are immersed together in a bath containing an electrolyte; the electrolyte (ie, a mild acid, such as selenic acid, sulfuric acid, oxalic acid, phosphoric acid, chromic acid, malonic acid, tartaric acid, lemon acid, malic acid, etc.). The application of electric current, electric charge and weak acid to the bath oxidizes the surface of the aluminum substrate to form alumina, and nanopores grow perpendicular to the surface of the aluminum substrate. The AAO film is typically grown on one or both surfaces of the aluminum foil to a thickness in the range of about 0.05 μm to about 70 μm and an average nanopore size in the range of about 1 nm to about 800 nm. The porous layer of the AAO membrane is separated from the aluminum foil by a dense layer of alumina with a thickness of tens to hundreds of nanometers, which is also referred to as a barrier layer.

In another embodiment, the anodic metal oxide film used herein is an anodic titanium oxide (ATO) film. ATO films with controllable nanopore size and good uniformity are formed by anodizing titanium foils in a solution containing fluorine ions such as hydrofluoric acid or ammonium fluoride and a suitable electrolyte. One skilled in the art can prepare ATO films according to well known literature methods. For example, A. Haring et al. in Materials 2012, 5, pp. 1890-1909 teach a number of experimental conditions to obtain ATO films with controllable pore structure and porous layer thickness. For other references, see US2010/0187172A1. Similarly, ATO films can be grown on both side surfaces of the titanium foil to a thickness in a range of about 0.05 μm to about 1000 μm and an average nanopore size in a range of about 15 nm to about 700 nm. The porous layer is separated from the titanium foil by a dense layer of titanium dioxide with a thickness of tens to hundreds of nanometers.

等人在J.Solid State Electrochem.2014,18，第3081–3090页中和由H.Tsuchiya等人在Chemical Physics Letters 2005,410，第188-191页中教导的方法。In yet another embodiment, the anodic metal oxide film used herein is an anodic zirconium oxide film. Anodized zirconium films with controllable nanopore size and good uniformity are formed by anodizing zirconium foils in a solution containing fluoride ions such as hydrofluoric acid and a suitable electrolyte. One skilled in the art can prepare anodized zirconium oxide films according to well known literature methods. For example, by M.

et al. in J. Solid State Electrochem. 2014, 18, pp. 3081-3090 and the methods taught by H. Tsuchiya et al. in Chemical Physics Letters 2005, 410, pp. 188-191.

While the anodic metal oxide film imparts scratch resistance to the composite film of the present invention, it also compromises the overall flexibility of the composite film. Therefore, the thickness of the anodic metal oxide film needs to be optimized. Furthermore, the polymer layer of the composite film of the present invention is formed by applying a liquid polymer composition on the anodic metal oxide film in the absence of a binder or other adhesion aid. Therefore, the thickness of the porous layer ( _Tp ), the average pore size of the nanopores ( _Dp , meaning the diameter of the nanopores) and the average pore spacing ( _Dint ) should be optimized to obtain good to excellent bonding.

Preferably, the thickness (T _p ) of the porous layer of the anodic metal oxide film may be in the range of about 0.5 μm to about 7 μm, or about 1.0 μm to about 5 μm; the thickness (T _d ) of the dense layer may be in the range of about 0.5 μm to about 7 μm, or about 1.0 μm to about 5 μm; In the range of about 2 nm to about 300 nm, or about 5 nm to about 200 nm, or about 10 nm to about 100 nm. Preferably, within the porous layer of the anodic metal oxide film, the average pore size (D _p ) of the nanopores may be in the range of about 1 nm to about 250 nm, or about 3 nm to about 100 nm, or about 5 nm to about 50 nm; nanopores The average pore spacing (D _int ) may be in the range of about 5 nm to about 500 nm, or about 10 nm to about 250 nm, or about 20 nm to about 125 nm; and the D _p /D _int ratio may be in the range of about 0.1 to about 0.9, or about In the range of 0.15 to about 0.7, or about 0.2 to about 0.5.

Suitable anodized aluminum foils and anodized titanium foils are commercially available. For example, anodized aluminum foil can be purchased from Shanghai ShangMu Technology Co., Ltd. (China) and Anometal Aluminium Co., Ltd. (China); anodized Titanium foils of ® are available from InRedox (USA).

polymer layer

The polymer layer of the present invention comprises polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polyimide (PI), or a copolymer thereof. Considering flexibility and mechanical properties, the thickness of the polymer layer is in the range of about 5 μm to about 250 μm, or about 15 μm to about 150 μm, or about 25 μm to about 75 μm.

The polymer layer is formed on the anodic metal oxide film of the anodized metal foil by applying a liquid polymer composition. The polymer composition may contain a polymer resin such as polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polyamic acid (PAA) (ie polyimide (PI)) in a suitable solvent. precursor), or their copolymers. The liquid polymer composition can be in the form of a solution or dispersion, depending on the solvent chosen and the concentration of the particular polymer resin or its precursor.

Compositions containing PVF or PVDF

Polyvinyl fluoride (PVF) suitable for use in forming the polymer layer according to the present invention includes its homopolymers and copolymers comprising at least 60 mole %, or at least 80 mole % of fluorinated ethylene.

Polyvinylidene fluoride (PVDF) suitable for use in forming the polymer layer according to the present invention includes its homopolymers and copolymers comprising at least 60 mol %, or at least 80 mol %, of vinylidene fluoride.

The comonomers of the PVF copolymers and PVDF copolymers used in the practice of the present invention may be fluorinated, or non-fluorinated, or mixtures thereof. The term "copolymer" refers to a copolymer of PVF or PVDF with any number of other fluorinated monomer units to form binary copolymers, terpolymers, tetrapolymers, and the like. If non-fluorinated monomers are used, the amount used should be limited so that the copolymer retains the desired properties of the fluoropolymer, ie, scratch resistance, flexibility and/or clarity, and the like. Suitable PVF copolymers are taught by US Patent Nos. 6,242,547 and 6,403,740 to Ushold.

In some embodiments, PVF homopolymers and PVDF homopolymers are well suited for the practice of the present invention.

The polymer layer of the present invention is formed by applying the polymer composition to the anodic metal oxide surface of the anodized metal foil.

Solutions or dispersions of PVF and PVDF are typically prepared using solvents with sufficiently high boiling points to avoid bubble formation during film formation/drying.

In some embodiments of the present invention, suitable PVF compositions are prepared as dispersions, particularly for PVF homopolymers. Preferred PVF dispersions are made in dimethylacetamide (DMAc), propylene carbonate, gamma-butyrolactone, N-methyl-2-pyrrolidone (NMP) and dimethylsulfoxide (DMSO) of.

In some embodiments of the present invention, suitable PVDF compositions are prepared as dispersions or solutions, depending on the solvent chosen. Suitable solvents include acetone, methyl ethyl ketone (MEK) and tetrahydrofuran (THF).

The concentration of polymeric resin in these solutions or dispersions can be adjusted to achieve a useful viscosity for the solution, and can vary with the particular polymeric resin, other components of the composition, and the process equipment and conditions used.

Preferably, for solutions, the PVF or PVDF is present in an amount of from about 10% to about 25% by weight based on the total weight of the polymer composition. For dispersions, the PVF or PVDF is preferably present in an amount of from about 25% to about 60% by weight based on the total weight of the polymer composition.

商购获得；PVDF组合物也可以从Arkema Co.以商品名

和Kynar

商购获得。PVF dispersions are available from EI du Pont de Nemours and Company (USA) (hereinafter referred to as "DuPont") under the trade name

Commercially available; PVDF compositions are also available from Arkema Co. under the tradename

and Kynar

Commercially available.

Polymer composition comprising polyamic acid

Polyimides are generally produced by reacting a dianhydride component with a diamine component in a molar ratio of about 0.90 to 1.10 to form a polyamic acid, followed by imidization at temperatures up to 500°C. The molecular weight of the thus formed polyamic acid can be adjusted by changing the molar ratio of the dianhydride component to the diamine component.

The polyimides suitable for forming the polymer layers according to the invention are derived from the corresponding polyamic acid compositions.

The dianhydride component is generally any aromatic dianhydride, aliphatic dianhydride, or cycloaliphatic dianhydride, including the corresponding diacid diester, diacid halide ester, or tetracarboxylic acid derivative of the dianhydride.

Examples of dianhydrides include, but are not limited to, pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-di Phenyl ether tetracarboxylic anhydride (ODPA), 3,3',4,4'-benzophenone-tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenylsulfone tetracarboxylic acid di Anhydride (DSDA), 2,2-bis-(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2 ,3,4-tetrahydro-naphthalene-1,2-dicarboxylic anhydride (DTDA), 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propanedianhydride (BPADA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA), cyclobutanetetracarboxylic dianhydride (CBDA), ethylenediaminetetraacetic acid dianhydride (EDTE), etc.

The diamine component is generally any aromatic diamine, aliphatic diamine or cycloaliphatic diamine. Examples of diamines include, but are not limited to, 1,4-phenylenediamine (PPD), 1,3-phenylenediamine (MPD), 2,2'-bis(trifluoromethyl)benzidine (TFMB), 4, 4'-diaminodiphenyl ether (4,4'-ODA), 3,4'-diaminodiphenyl ether (3,4'-ODA), 2,2-bis[4-(4-aminophenoxy) base)phenyl]propane (BAPP), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (BAHFP), 4,4'-bis(4-aminophenoxy)biphenyl ( p-BAPB), 2,2-bis(3-aminophenyl)hexafluoropropane (BAPF), bis[4-(3-aminophenoxy)phenyl]sulfone (m-BAPS), 2,2- Bis-[4-(4-Aminophenoxy)phenyl]sulfone (p-BAPS), m-xylylenediamine (m-XDA), 2,2-bis(3-amino-4-methylphenyl) ) hexafluoropropane (BAMF), 1,3-bis(aminoethyl)cyclohexane (m-CHDA), 1,4-bis(aminomethyl)cyclohexane (p-CHDA), 1,3- Cyclohexanediamine, trans-1,4-cyclohexanediamine, etc.

The above-mentioned dianhydrides and diamines can be used alone to form a polyimide homopolymer, or as a mixture of two or more monomer units to form a polyimide copolymer. For example, in the present disclosure, a polyimide copolymer derived from a dianhydride component with PMDA and 6FDA in a molar ratio of 70:30 and a diamine component composed of PPD in a molar ratio of 100 may be PMDA/6FDA //PPD(70:30:100) representation.

Since the composite film of the present invention can be used in flexible display devices instead of glass panels, it is highly desirable to have high optical transparency. "Optically transparent" means that the composite film allows light in the visible region to pass through without loss or distortion (eg, without significant loss or distortion). To obtain "transparent" polyimide layers, the usual strategy is to incorporate aromatic monomers substituted with strongly electronegative groups such as trifluoromethyl, or aliphatic monomers, or cycloaliphatic monomers Such as cyclobutane or cyclohexane. Suitable polyimide copolymers are described in US2008/0020217, US2015/0344625 and WO 2018/208639.

The polyamic acid is produced by mixing a dianhydride component and a diamine component in an organic solvent having a high boiling point. Preferably, the organic solvent is capable of dissolving polyamic acid and has a boiling point lower than 225°C. Suitable organic solvents include, but are not limited to, dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylacetoacetamide (DMAA), dimethylsulfoxide (DMSO), N-methyl- 2-pyrrolidone (NMP), γ-butyrolactone, ε-caprolactone, or a mixture thereof. In one embodiment, the solvent is DMAc, DMAA, NMP, or a mixture thereof.

Preferably, for solutions, the polyamic acid is present in an amount of from about 10% to about 40% by weight based on the total weight of the polymer composition.

The method of making the composite membrane of the present invention

As shown in Figure 3, the method for manufacturing the composite membrane of the present invention comprises the following steps:

(i) providing an anodized metal foil 200 or 250 and a polymer composition;

(ii) applying the polymer composition over an anodized surface of the anodized metal foil 200 or 250;

(iii) heating the product of step (ii) at a temperature ranging from 50°C to about 500°C for 30 seconds to 6 hours to form polymer layer 10;

(iv) optionally, removing the uncoated anodic metal oxide film 40 from the product 350 of step (iii) to expose the metal foil 30; and

(v) chemically or mechanically removing the metal foil 30 and, if present, the uncoated anodic metal oxide film 40 from the product 300 or 350 of step (iii) or from the product 450 of step (iv);

in

The anodized metal foil includes a metal foil 30 and at least one anodic metal oxide film 20 grown on the surface of the metal foil by anodization;

the anodic metal oxide film 20 has a nanostructure including a dense layer and a porous layer having a plurality of nanopores, and the dense layer of the anodic metal oxide film is in contact with the metal foil; and

The polymer composition comprises at least one polymer resin or a precursor thereof.

In one embodiment of the method of the present invention, the anodized metal foil is anodized on one or both surfaces thereof; and the metal foil is composed of aluminum, titanium, zirconium, and alloys thereof.

In one embodiment of the method of the present invention, the polymer composition comprises polyvinyl fluoride, polyvinylidene fluoride, polyamic acid, or a copolymer thereof.

In step (ii) of the method of the present invention, techniques for applying the liquid polymer composition on the surface of the anodic metal oxide film of the anodized metal foil include conventional methods such as spraying, casting, spin coating, roll coating, knife coating , curtain coating, gravure coating, or any other method that allows a uniform coating to be applied without streaking or other defects. Casting and spin coating are the most convenient methods of application.

The term "spin coating" is intended to denote a specific process for depositing uniform thin films onto flat substrates. Typically in "spin coating", a small amount of coating material is applied to the center of a substrate that is spinning at low speeds or not spinning at all. The substrate is then rotated at a specific speed in order to spread the coating material evenly by centrifugal force.

In step (iii) of the method of the present invention, the heating temperature varies widely with the polymer resin used in the polymer composition, and may range from room temperature to the temperature of the oven, which should be high At the temperature required for the polymer composition to form a continuous film as polymer layer 10 .

A person skilled in the art can select a suitable temperature ramp according to the polymer solution or dispersion employed to facilitate the formation of the polymer layer without difficulty.

After applying the polymer composition in step (ii) of the method, the wet coating is typically soft baked to remove the solvent. The term "soft bake" refers to a common process in electronics manufacturing, where cast or spin-coated materials are heated to remove solvent and cure thin films. As a preparatory step for subsequent thermal treatment of the coated layer or film, the soft bake is typically performed on a hot plate or in an exhausted oven at a temperature between 50°C and 150°C.

When using some compositions that are PVF or solutions of PVDF, the wet coating can be allowed to air dry at ambient temperature. Although not required, heat is often desired to dry the wet coating more quickly. Preferably, the polymer composition comprising PVF or PVDF is heated to a temperature of about 50°C to about 250°C for about 0.5 minutes to about 5 minutes.

For polymer compositions comprising polyamic acid, heating is generally used to remove the solvent and carry out the imidization reaction. The temperature at which the polyamic acid is imidized should be lower than the temperature at which the polyimide undergoes significant thermal degradation or discoloration. It should also be noted that operating under an inert atmosphere is generally preferred, especially when higher processing temperatures are employed for the imidization reaction.

For polyamic acid compositions suitable for forming polymer layers composed of polyimide, temperatures of about 250°C to about 500°C are generally employed. Catalysts that accelerate the imidization process can then effectively achieve higher degrees of imidization at temperatures between about 200°C and 300°C. The length of time for each curing step in the temperature ramp is also an important process consideration. In general, the time for the highest temperature cure should be kept to a minimum. One skilled in the art can recognize the balance between temperature and time to optimize the properties of the polyimide for a particular end use.

In step (iv) of the method of the present invention, when both sides of the anodized metal foil employed are anodized (ie, denoted as anodized metal foil 250 in FIG. 3 ), the uncoated anode can be removed or separated Metal oxide film 40 to expose metal foil 30 . For example, the uncoated anodic metal oxide film 40 can be etched away or separated by treatment with an aqueous acid containing solution such as, but not limited to, phosphoric acid for alumina, hydrochloric acid for titania, Sulfuric acid of zirconia, etc. Alternatively, the uncoated anodic metal oxide film 40 may be chemically or mechanically removed together with the metal foil 30 in step (v).

In step (v) of the method of the present invention, the metal foil 30 on the opposite side of the polymer layer 10 in the product of step (iii) or step (iv) and, if present, the uncoated metal foil 30, may be chemically or mechanically removed. Anode metal oxide film 40 .

For example, due to the weak interfacial bonding force between the anodized zirconium film and the pick foil, the pick foil can be easily mechanically peeled off from the anodized zirconium film, eg, using tweezers. Other mechanical methods include milling or grinding.

In one embodiment of the method for manufacturing a composite film of the present invention, wherein the metal foil 30 is removed by chemically treating the product of step (iii) or the product of step (iv) with an etchant.

Suitable etchants for removing aluminum foil include, but are not limited to, aqueous solutions containing iron (III) chloride (FeCl ₃ ) and copper (II) chloride (CuCl ₂ ). For the removal or separation of the titanium foil, tin(IV) chloride (SnCl ₄ ) or an aqueous solution of hydrochloric acid can be used.

The composite membrane of the present invention

The composite film of the present invention exhibits flexibility, scratch resistance, and little risk of damage to the composite film even in the state of repeated continuous bending or folding for a long time. Therefore, the composite film of the present invention can be used as a cover sheet for flexible displays, as a substrate material for fine-pitch FCCL, as a cover sheet for flexible solar cells, and the like.

The overall thickness of the composite films of the present invention may range from about 5 μm to about 250 μm, or about 20 μm to about 90 μm, or about 30 μm to about 70 μm, considering flexibility, optimal mechanical properties, and optional optical clarity.

In the present invention, "flexible" refers to a state of being flexible to such an extent that when bent on a cylindrical shaft with a radius greater than 1.5 mm, or 1.0 mm, according to the method described in ASTM D522/D522M-17, it does not Cracks appear.

Depending on the application, the composite films of the present invention can be colorless and optically clear. In one embodiment, the composite films of the present invention have a total light transmittance between 400 nm and 800 nm of about 80% or greater as measured by ASTM D1003 Standard Test Method for Haze and Light Transmission of Transparent Plastics. Exemplary applications requiring optically transparent composite films include, but are not limited to, use as cover sheets for flexible displays or flexible solar cells.

Depending on the application, the composite films of the present invention exhibit good insulating properties, with a dielectric constant in the range of 4 or less at 2.45 GHz as measured according to the IEC61189-2-721 method.

The scratch resistance properties of the composite films of the present invention can be evaluated by an abrasion test. Assuming that when the composite film is used as a cover sheet for a flexible display device (eg, under typical usage conditions), the load applied to the cover sheet hardly exceeds about 1 Kg/4 cm ² . Therefore, the abrasion test can be carried out by moving steel wool (Liberon #0000) back and forth from left to right on the surface of the anodic metal oxide film of the composite film for many times under a load of 1Kg/4cm ² , and checking Whether scratches have occurred on the surface of the composite film.

The following examples and comparative examples are provided to illustrate specific details of one or more embodiments. It should be understood, however, that the embodiments are not limited to the specific details described.

Example

Material:

· AAO-1 : 280 μm double-sided anodized aluminum foil with Al ₂ O ₃ -Al-Al ₂ O ₃ three-layer nanostructure, commercially available from Anometal Aluminum Co., Ltd. under the trade name Bright Alugrip Industry Co., Ltd.). One side of the Al ₂ O ₃ film has a smooth mirror-like surface (hereinafter referred to as "front side"), while the other side of the Al ₂ O ₃ film has a matte surface (hereinafter referred to as "back side"). The porous layer thickness (T _p ), dense layer thickness (T _d ), nanopore size (D _p ), and inter-pore distance (D _int ) of the front-side anodic aluminum oxide (AAO) films were measured by scanning electron microscopy (SEM), and are listed in Table 1.

· AAO-2 : 280 μm double-sided anodized aluminum foil with Al ₂ O ₃ -Al-Al ₂ O ₃ three-layer nanostructure, commercially available from Atotech Aluminium Co., Ltd. under the trade name Bright Alugrip. The porous layer thickness (T _p ), dense layer thickness (T _d ), nanopore size (D _p ) and inter-pore distance (D _int ) of the front-side AAO films were measured by SEM and are listed in Table 1.

AAO-3 : 200 μm single-sided anodized aluminum foil with Al- _{Al2O3 two} -layer nanostructure, catalog number AAO-SP-21 was purchased from Shanghai Shangmu Technology Co., Ltd. (Shanghai Shangmu Technology Co., Ltd. Ltd). The porous layer thickness (T _p ), dense layer thickness (T _d ), nanopore size (D _p ) and inter-pore distance (D _int ) of the AAO film were measured by SEM, and listed in Table 1.

· AAO-4 : 200 μm single-sided anodized aluminum foil with Al-Al ₂ O ₃ two-layer nanostructure, catalog number AAO-SP-23 was purchased from Shanghai Shangmu Technology Co., Ltd. The porous layer thickness (T _p ), dense layer thickness (T _d ), nanopore size (D _p ) and inter-pore distance (D _int ) of the AAO film were measured by SEM, and listed in Table 1.

PI-A : about 20 wt% polyamic acid copolymer in DMAc solution derived from BPDA, 6FDA and TFMB in a molar ratio of about 60:40:100, obtained from DuPont, used to form a colorless polyimide layer.

PI-B : NMP solution containing about 11.2 wt% polyamic acid copolymer derived from BPDA, CBDA and TFMB in a molar ratio of about 60:40:100, obtained from DuPont, used to form a free color polyimide layer.

PI-C : about 20 wt% polyamic acid in DMAc solution derived from BPDA and PPD in a molar ratio of about 100:100, available from DuPont, used to form an amber polyimide layer .

44-1010购自Dupont，其在碳酸亚丙酯中包含约45重量％的聚氟乙烯。· PVF-A : Polyvinyl fluoride dispersion, trade name

44-1010 is available from Dupont and contains about 45 wt% polyvinyl fluoride in propylene carbonate.

Table 1

AAO-1 AAO-2 AAO-3 AAO-4 T_p, μm 1.5 4.4 0.3 10 T_d, nm 20 30 30 30 D_p, nm 9 11 30 30 D_int, nm 34 44 65 65 D_p/D_int 0.26 0.25 0.46 0.46

testing method:

The samples in the following examples passed some or all of the tests described below.

Total thickness: Using a standard digital thickness gauge (Model: SMD-565J-L, manufactured by TECLOCK Corporation (Japan)), the total thickness of the composite film sample was measured at 4 peripheral points and one point near the center, where the minimum indicated is 0.001mm). The measurements were averaged and reported in Table 2.

Total light transmittance and haze: Using a haze meter (model: WGT-S, manufactured by Shanghai Jingke (China)), according to the ASTM D1003 method, 3 pieces were measured on a 3cm×3cm test specimen Differences, the measurements were averaged and reported in Table 2.

Abrasion test: Using a reciprocating abrasion tester (model: ZJ-339, manufactured by Shenzhen Zhijia Equipment Co., Ltd. (Shenzhen Zhijia) (China)), an abrasion test was performed on the test sample (3 cm×10 cm). The #0000 steel wool under a load of 1Kg/4cm ² was brought into contact with the surface of the anodic metal oxide film of the test specimen, and moved back and forth 5000 times. After the abrasion test, if no visible defects were observed on the surface of the anodic metal oxide film, the test specimen was considered to have passed the abrasion test, and the results are reported in Table 2.

Flexibility Testing: Flexibility testing is performed by bending a composite film sample so that the anodic metal oxide film faces inward (ie, bends in) or faces outwards (ie bends out). According to the method described in ASTM D522/D522M-17, with a cylindrical shaft bending tester (Model: WQ-II, manufactured by Shanghai Modern Environment Engineering Technique Co., Ltd. (China) (Shanghai Modern Environment Engineering Technology Co., Ltd.)) , to measure the sample (1cm×3cm). The specimen is bent on a cylindrical axis of a specific radius, at 0.5 mm intervals, from 5 mm to 1 mm, when the specimen can recover from the bend without any creases on the surface of its anodic metal oxide film or cracks, reported as the minimum radius of the cylindrical axis. The results for each example and comparative example are reported in Table 2.

Dielectric constant and dielectric loss at 2.45GHz: According to the method described in IEC 61189-2-721, using an electric strength tester (model: 7100-5-149-PB, manufactured by Hubbell-Anmex International Pte. Ltd. ( China) (manufactured by Hubble Amers International Co., Ltd.) to measure the sample (10 cm×10 cm).

Preparation of Example 1

Using a coater (COATMASTER 509MC, manufactured by ERICHSEN GmbH & Co. KG (Germany)), the polyamic acid composition (PI-A) was cast on the front side anode of anodized aluminum foil (AAO-1, size: 30 cm×20 cm) on the aluminum oxide film. The wet coated sheet was heated from 25°C to 150°C in 30 minutes to remove the solvent and then heated under nitrogen atmosphere using the following temperature ramp: 25°C to 200°C in 40 minutes, at 200°C. ℃ for 30 minutes, oven temperature from 200℃ to 360℃ in 80 minutes, 30 minutes at 360℃, and cooling from 360℃ to 30℃ in 120 minutes to convert the polyamic acid precursor into the corresponding polyimide. An anodized aluminum foil with a front surface covered with a colorless polyimide layer was obtained, the anodized aluminum foil had a four-layer nanostructure of [PI/Al ₂ O ₃ -Al-Al ₂ O ₃ ].

The anodized aluminum foil covered with the polymer layer was immersed in a phosphoric acid solution (40 wt% phosphoric _acid in water) for ₁₀ min to remove the uncoated backside Al ₂ O ₃ layer to obtain a ] of the three-layer nanostructured coating.

The coating film was placed in a Rota-Spray processor (model: 500-702, manufactured by MEGA ELECTRONICS LTD. (UK)), and a ferric chloride solution (42 wt% ferric chloride) was sprayed on the surface of its aluminum foil. in water) for 30 minutes while maintaining the processing chamber at a temperature below 60°C to remove the aluminum foil, rinse with deionized water to produce a two-layer nanostructure with [PI/Al ₂ O ₃ ] and its average total thickness The flexible composite film of one embodiment of the present invention is 66 μm.

Preparation of Example 2

The polyamic acid solution (PI-B) was spin-coated in a spin coater (CHY-AC200SE, manufactured by Henan Chengyi Equipment Science and Technology Co., Ltd. (China)) on Anodized aluminum foil (AAO-1, size: 10 cm x 10 cm) on the front anodized aluminum film. The wet coated sheets were soft baked on a hot plate at 80°C for 10 minutes. Repeat the spin coating and heating steps 5 times.

The resulting polyamic acid-coated sheet was placed on a hot plate in a glove box under an argon atmosphere, and then heated using the following temperature ramp: from 25°C to 100°C in 30 minutes, at 100°C Hold for 32 minutes, increase temperature from 100°C to 200°C in 20 minutes, hold at 200°C for 30 minutes, increase temperature from 200°C to 320°C in 48 minutes, hold at 320°C for 60 minutes, then cool to 25°C and kept overnight to convert the polyamic acid precursor to the corresponding polyimide. An anodized aluminum foil with a front surface covered with a colorless polyimide layer was obtained, the anodized aluminum foil had a four-layer nanostructure of [PI/Al ₂ O ₃ -Al-Al ₂ O ₃ ].

Anodized aluminum foil covered with a polymer layer was treated with phosphoric acid solution (40 wt%) as described in Example ₁ to remove the uncoated backside _Al2O3 layer, followed by ferric chloride solution (42 wt%) ) to remove the aluminum foil. A flexible composite film of one embodiment of the present invention was obtained, which has a two-layer nanostructure of [PI/Al ₂ O ₃ ] and an average total thickness of 67 μm.

Preparation of Example 3

Example 3 was prepared similarly to the procedure described in Preparation Example 2, except that the polyamic acid solution (PI-B) was spin-coated on the front anodized aluminum film of anodized aluminum foil (AAO-2). Repeat the spin coating and soft bake steps 5 times. After heating with the same temperature ramp, the uncoated backside Al ₂ O ₃ layer was removed, followed by removal of the Al foil, resulting in a two-layer nanostructure with [PI/Al ₂ O ₃ ] and an average total thickness of 34 μm. A flexible composite membrane of one embodiment of the invention.

Preparation of Example 4

The polyamic acid solution (PI-C) was cast on the front anodized aluminum film of an anodized aluminum foil (AAO-1, 33 cm×100 m) using a slit extrusion coater (manufactured by INOKIN (Japan)). The polyamic acid coated sheet was heated under nitrogen atmosphere using the following temperature ramp: heat from 25°C to 200°C in 35 minutes, hold at 200°C for 30 minutes, ramp the temperature from 200°C in 80 minutes Raising to 360°C, holding at 360°C for 30 minutes, and cooling the temperature from 360°C to 30°C over 120 minutes to convert the polyamic acid precursor to the corresponding polyimide. Anodized aluminum foil with a front surface covered with an amber polyimide layer was obtained, the anodized aluminum foil had a four-layer nanostructure of [PI/Al ₂ O ₃ -Al-Al ₂ O ₃ ].

Similar to that described in Example 1, the anodized aluminum foil covered with the polymer layer was treated with phosphoric acid solution (40 wt%) to remove the uncoated backside _Al2O3 layer, followed by ferric _chloride solution (42 wt%) %) to remove the aluminum foil. A flexible composite film of one embodiment of the present invention was obtained having a two-layer nanostructure of [PI/Al ₂ O ₃ ] and an average total thickness of 29 μm.

Preparation of Example 5

The polyvinyl fluoride solution (PVF-A) was diluted with ethylene glycol butyl ether acetate at a weight ratio of 20:1 and then cast on the anode using an automatic coater (AB3220, manufactured by TQC Sheen BV–HQ (Netherlands)). Alumina foil (AAO-1, size: 30 cm x 20 cm) on the front anodized aluminum film. The wet coated sheet was heated in an oven at 220 °C for 1 min to form anodized aluminum foil covered with a colorless PVF layer with [PVF/Al ₂ O ₃ -Al-Al ₂ O ₃ ] The four-layer nanostructure.

Similar to that described in Example 1, the anodized aluminum foil covered with the polymer layer was then treated with phosphoric acid solution (40 wt %) and then with ferric chloride solution (42 wt %) to provide a solution with [PVF/Al A flexible composite film of one embodiment of the present invention having a two-layer nanostructure of ₂ O ₃ ] and an average total thickness of 38 μm.

Preparation of Comparative Example 1

Similar to that described in Example 2, a spin-coater (CHY-AC200SE, manufactured by Henan Chengyi Equipment Technology Co., Ltd. (China)) was used to spin-coat polyamic acid solution (PI-B) on anodized aluminum foil (AAO- 3, 12cm × 12cm) on the anodized aluminum film. The wet coated sheets were soft baked on a hot plate at 80°C for 10 minutes. Repeat the spin coating and heating steps 5 times.

The polyamic acid coated sheet was placed on a hot plate in a glove box under argon atmosphere and then heated using the same temperature ramp as described in Example 2 to obtain a colorless polyimide covered with colorless polyimide. layer of anodized aluminum foil with a three-layer nanostructure of [PI/Al ₂ O ₃ -Al]. After treatment with a 42 wt % ferric chloride solution, a comparative composite film was obtained with a two-layer nanostructure of [PI/Al ₂ O ₃ ] and an average overall thickness of 20 μm.

Preparation of Comparative Example 2

Comparative Example 2 was prepared similarly to the procedure described for the preparation of Comparative Example 1, except that the polyamic acid solution (PI-B) was spin-coated on the anodized aluminum film of anodized aluminum foil (AAO-4). Repeat the spin coating and heating steps 10 times. After heating with the same temperature ramp and removal of the aluminum foil, a comparative composite film was obtained. The obtained composite film had a two-layer nanostructure of [PI/Al ₂ O ₃ ] and an average total thickness of 78 μm.

Table 2

E1 E2 E3 E4 E5 CE1 CE2 Anodized aluminum foil AAO-1 AAO-1 AAO-2 AAO-1 AAO-1 AAO-3 AAO-4 Porous layer thickness μm 1.5 1.5 4.4 1.5 1.5 0.3 10 source of polymer layer PI-A PI-B PI-B PI-C PVF-A PI-B PI-B Composite film thickness μm 66 67 34 29 38 20 78 Total light transmittance (%) 88.3 85.4 84.3 ND 91.1 87.0 84.2 Haze % 1.5 2.3 4.2 ND 5.2 0.7 6.5 Scratch resistance test pass pass pass pass pass Failed pass Outer bending radius (mm) 1 1 1 1 1 1 2 Inner bending radius (mm) 1.5 1 1 1 1 1 2 Dielectric constant@2.45GHz ND ND ND 3.82 ND ND ND Dielectric Loss@2.45GHz ND ND ND 0.0054 ND ND ND

*ND: Not determined.

Claims (12)

1. A composite membrane, comprising:

a polymer layer and an anodic metal oxide film,

wherein

The anodic metal oxide film is derived from an anodized metal foil;

the anodic metal oxide film has a nanostructure comprising a dense layer and a porous layer having a plurality of nanopores;

the porous layer of the anodic metal oxide film is embedded in the polymer layer; and is

The composite film has an out-fold bend radius of 1.5mm or less and an in-fold bend radius of 1.5mm or less as measured according to the method of ASTM D522/D522M-17.

2. The composite film of claim 1, wherein the total thickness of the composite film is in the range of 5 μ ι η to 250 μ ι η.

3. The composite membrane of claim 1 or 2, wherein the thickness (T) of the porous layer of the anodic metal oxide membrane_p) In the range of 0.5 to 7.0 μm, and a thickness (T) of the dense layer of the anodic metal oxide film_d) In the range of 2nm to 300 nm.

4. The composite membrane of any one of claims 1-3, wherein the porous layer of the anodic metal oxide membrane comprises a plurality of nanopores having an average pore diameter (D)_p) 1nm to 250nm, average pore spacing (D)_int) Is 5nm to 500nm, and D_p/D_intThe ratio is in the range of 0.1 to 0.9.

5. The composite film of any of claims 1-4 wherein the metal foil is comprised of aluminum, titanium, zirconium, and alloys thereof.

6. The composite film of any of claims 1-5, wherein the polymer layer comprises polyvinyl fluoride, polyvinylidene fluoride, polyimide, or copolymers thereof.

7. The composite film of any of claims 1-6, wherein the composite film has a dielectric constant of 4 or less at 2.45GHz as measured according to IEC61189-2-721 method.

8. The composite film of any of claims 1-6, wherein the composite film has a total light transmission of 80% or greater between 400nm and 800 nm.

9. A method of making the composite film of any one of claims 1-8, comprising:

(i) providing an anodized metal foil and a polymer composition;

(ii) applying said polymer composition over an anodized surface of said anodized metal foil;

(iii) (iii) heating the product of step (ii) at a temperature in the range of 50 ℃ to 500 ℃ for 30 seconds to 6 hours to form a polymer layer;

(iv) optionally, removing the uncoated anodic metal oxide film, if present, in the product of step (iii) to expose the metal foil; and

(v) (iv) removing the metal foil and, if present, uncoated anodic metal oxide film from the product of step (iii) or the product of step (iv) by a chemical or mechanical process;

wherein

The anodized metal foil includes a metal foil and at least one anodic metal oxide film grown on a surface of the metal foil by anodic oxidation;

the anodic metal oxide film has a nanostructure comprising a dense layer and a porous layer having a plurality of nanopores, and the dense layer of the anodic metal oxide film is in contact with the metal foil; and is

The polymer composition comprises at least one polymer resin or a precursor thereof.

10. The method of claim 9, wherein the metal foil is removed by chemically treating the product of step (iii) with an etchant.

11. The method of claim 9, wherein the anodized metal foil is anodized on a surface of one or both sides thereof; and the metal foil is composed of aluminum, titanium, zirconium, and alloys thereof.

12. The method of claim 9, wherein the polymer composition comprises polyvinyl fluoride, polyvinylidene fluoride, polyamic acid, or copolymers thereof.

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