Polyamide composite film and method of manufacture, electronic device

Abstract

The application discloses a kind of polyamide composite film and preparation method, electronic device, it is related to polyamide film technical field, to solve the problem that the flame retardant of existing flame-retardant polyamide film can be separated with time change, cause the flame retardant instability of polyamide film.The polyamide composite film includes first polyamide layer, flame-retardant layer and second polyamide layer, the flame-retardant layer is bonded on the surface of the first polyamide layer, and the second polyamide layer is bonded on the surface of the flame-retardant layer away from the first polyamide layer.The preparation method is used to prepare the polyamide composite film, and the electronic device uses the polyamide composite film.The polyamide composite film and preparation method, electronic device provided by the application are used when, with good flame-retardant stability, improve the safety of polyamide composite film.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyamide film, and particularly relates to a polyamide composite film and a preparation method and an electronic device. BACKGROUND

[0002] At present, polyamide resin films such as biaxially oriented polyamide (BOPA) films have high strength, good barrier property and good transparency, and are widely used in electrical appliances, busbars, disk drives, displays, switch joints, vacuum bags and food packaging bags. However, the oxygen index of polyamide is 24, which belongs to flammable materials, and the flame retardance is poor, which seriously limits the application.

[0003] The traditional flame-retardant method generally adds a flame retardant when the polyamide is polymerized, the flame retardant is fused with the polyamide matrix for a long time, the compatibility is increased, the influence on the flowability of the melt is small, the process parameter setting requirement is relatively loose during the melt stretching process, and the controllability is strong. However, although the flowability is increased, the added flame retardant will still precipitate with the extension of time due to the incompatibility with the polyamide, and the product quality is unstable. Therefore, it is necessary to develop a polyamide composite film in which the flame retardant will not precipitate with the extension of time. SUMMARY

[0004] The purpose of the present application is to provide a polyamide composite film and a preparation method and an electronic device, the flame retardant in the polyamide composite film will not precipitate with the extension of time, the stability of the polyamide composite film is improved, and thus the safety of the polyamide composite film is improved.

[0005] In a first aspect, the present application provides a polyamide composite film, comprising a first polyamide layer, a flame-retardant layer and a second polyamide layer, the flame-retardant layer is bonded to the surface of the first polyamide layer, and the second polyamide layer is bonded to the surface of the flame-retardant layer away from the first polyamide layer.

[0006] Compared with the prior art, the polyamide composite film provided by the present application has the following advantages:

[0007] The polyamide composite film provided by the embodiment of the present application comprises a first polyamide layer, a flame-retardant layer and a second polyamide layer. The flame-retardant layer is bonded to the surface of the first polyamide layer, and the second polyamide layer is bonded to the surface of the flame-retardant layer away from the first polyamide layer. Therefore, the chemical bonds of the first polyamide layer and the chemical bonds of the second polyamide layer can be connected together through the flame-retardant layer. When the polyamide composite film is used for a long time, the thermal motion of the amorphous segments in the polyamide contained in the first polyamide layer and the polyamide contained in the second polyamide layer can be avoided. Therefore, the flame retardant with poor compatibility with the polyamide can be prevented from overcoming the resistance and migrating to the surface of the polyamide. In turn, the deterioration of the flame retardant precipitated and migrated to the surface of the polyamide can be avoided. As a result, the flame-retardant effect of the polyamide composite film is improved, and the safety of the polyamide composite film is improved. Meanwhile, the flame-retardant layer is bonded to the surface of the first polyamide layer, and the second polyamide layer is bonded to the surface of the flame-retardant layer away from the first polyamide layer. The flame-retardant layer can exist between the first polyamide layer and the second polyamide layer. At this time, the flame-retardant layer is polymerized to the molecular chain of the polyamide, so that the flame retardant is stably connected with the polyamide. Since the upper and lower layers of the polyamide composite film are both polyamide molecular chains, the flame-retardant layer is bonded between the upper and lower polyamide layers. Even if the first polyamide layer and the second polyamide layer are stretched, the flame-retardant layer will not migrate to the surface of the polyamide. Therefore, the mechanical properties of the polyamide composite film are ensured, and the orientation of the polyamide composite film is maintained.

[0008] In addition, in the embodiment of the present application, since the molecular chains of the flame-retardant layer and the polyamide layer are connected, the solid-phase adhesion process steps of the flame-retardant layer and the polyamide layer can be omitted, the process steps are simplified, and the cost is saved.

[0009] As can be seen from the above, the flame retardant in the polyamide composite film provided by the present application will not precipitate as time goes on, the stability of the polyamide composite film is improved, and the safety of the polyamide composite film is improved.

[0010] In a second aspect, the present application also provides a preparation method of a polyamide composite film, comprising:

[0011] providing a first polyamide layer, and forming a flame-retardant layer on the surface of the first polyamide layer;

[0012] providing a second polyamide layer, and forming the second polyamide layer on the surface of the flame-retardant layer away from the first polyamide layer;

[0013] bonding the flame-retardant layer to the surface of the first polyamide layer and the surface of the second polyamide layer under heating conditions.

[0014] Compared with the prior art, the preparation method of the polyamide composite film provided by the present application has the same beneficial effects as the polyamide composite film provided by the first aspect, which will not be repeated here.

[0015] Thirdly, the present invention also provides an electrode sheet comprising the electrode material provided in the first aspect.

[0016] Compared with the prior art, the beneficial effects of the electrode sheet provided by the present invention are the same as those of the electrode material in the first aspect, and will not be repeated here.

[0017] Fourthly, the present invention also provides an electronic device comprising the polyamide composite film provided in the first aspect.

[0018] Compared with the prior art, the beneficial effects of the electronic device provided by the present invention are the same as those of the polyamide composite film in the first aspect, and will not be repeated here. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0020] Figure 1 This is a schematic diagram of the structure of the polyamide composite film according to an embodiment of the present invention;

[0021] Figure 2 This is a flowchart illustrating the preparation process of the polyamide composite film according to an embodiment of the present invention.

[0022] Figure label:

[0023] 100-Polyamide composite film, 101-Flame retardant layer, 102-First polyamide layer, 103-Second polyamide layer. Detailed Implementation

[0024] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0026] Currently, there are various manufacturing technologies for polyamide films, including calendering, T-type (extrusion casting) film forming (mainly used in non-oriented films), air blowing expansion, and T-type biaxial stretching film forming. Polyamide films have wide applications due to their inherent advantages, primarily in electrical appliances, busbars, disk drives, displays, and switch connectors.

[0027] Traditional flame retardant methods typically involve adding blended flame retardants during the polyamide melting process. These include brominated polystyrene, decabromodiphenyl ethane, tetrabromobisphenol A, magnesium hydroxide, aluminum hydroxide, antimony trioxide, TCPP, MPP, and MCA. For example, adding the flame retardant before the polyamide polymerization process allows for a longer integration time with the polyamide matrix, increasing compatibility and minimizing impact on melt flowability. This approach also allows for more flexible and controllable process parameter settings during melt stretching. However, while this method increases flowability, the added flame retardant can still precipitate over time, leading to product quality instability.

[0028] To address the aforementioned problems, embodiments of the present invention provide an electronic device that may include the polyamide composite film of the present invention. This prevents the flame retardant in the polyamide composite film from leaching out over time, thereby improving the stability and safety of the polyamide composite film. In practical applications, this electronic device may include electrical appliances, busbars, disk drives, displays, switch connectors, or other electronic devices; no limitation is made here.

[0029] The polyamide composite film provided in this embodiment of the invention can be applied to the above-mentioned electronic devices. Figure 1 A schematic diagram of the structure of the polyamide composite film according to an embodiment of the present invention is shown. Figure 1 As shown, the polyamide composite film 100 of this embodiment of the invention includes a first polyamide layer 102, a flame retardant layer 101 and a second polyamide layer 103. The flame retardant layer 101 is bonded to the surface of the first polyamide layer 102, and the second polyamide layer 103 is bonded to the surface of the flame retardant layer 101 opposite to the first polyamide layer 102.

[0030] The polyamide composite film provided in this embodiment of the invention includes a first polyamide layer, a flame-retardant layer, and a second polyamide layer. The flame-retardant layer is bonded to the surface of the first polyamide layer, and the second polyamide layer is bonded to the surface of the flame-retardant layer opposite to the first polyamide layer. Therefore, the flame-retardant layer can connect the chemical bonds of the first and second polyamide layers together. This prevents thermal motion of the amorphous segments in the polyamide in both the first and second polyamide layers during prolonged use, thus preventing flame retardants with poor compatibility from migrating to the polyamide surface and overcoming resistance. This also prevents the deterioration of flame retardants that have precipitated and migrated to the polyamide surface, thereby improving the flame-retardant effect and enhancing the safety of the polyamide composite film. Furthermore, the fact that the flame-retardant layer is bonded to the surface of the first polyamide layer and the second polyamide layer is bonded to the surface of the flame-retardant layer opposite to the first polyamide layer allows the flame-retardant layer to exist between the first and second polyamide layers. At this point, the flame-retardant layer polymerizes onto the polyamide molecular chains, allowing the flame retardant to be stably linked to the polyamide. Since both the upper and lower layers of the polyamide composite film are composed of polyamide molecular chains, the flame-retardant layer is bonded between the two polyamide layers. Even if the first and second polyamide layers are stretched, the flame-retardant layer will not migrate to the polyamide surface. Therefore, both the mechanical properties and orientation of the polyamide composite film are preserved.

[0031] As can be seen from the above, the flame retardant in the polyamide composite film provided by the present invention will not precipitate over time, thereby improving the stability of the polyamide composite film and thus improving its safety.

[0032] In one feasible embodiment, the flame-retardant layer of this invention contains a chain extender and a flame retardant. The flame retardant is grafted onto the polyamide in the first polyamide layer via the chain extender, and the polyamide in the second polyamide layer is grafted onto the surface of the flame-retardant layer opposite to the first polyamide layer via the chain extender. Therefore, the chain extender in the flame-retardant layer allows the flame retardant to undergo a solid-state polymerization reaction at the interface with the polyamide in the first and second polyamide layers. In this process, the chain extender can graft the flame retardant onto the molecular chain of the polyamide in the first polyamide layer, and the molecular chain of the polyamide in the second polyamide layer can be grafted onto the surface of the flame-retardant layer opposite to the first polyamide layer via the chain extender. This increases the molecular weight of the polyamide, avoiding the technical problem of low molecular weight caused by the flame retardant's steric hindrance during the reaction. Therefore, when using polyamide composite films for a long time, thermal motion of amorphous segments in the polyamide contained in the first polyamide layer and the polyamide contained in the second polyamide layer can be avoided. This prevents flame retardants with poor compatibility with polyamide from migrating to the polyamide surface by overcoming resistance, thereby preventing the deterioration of flame retardants that have precipitated and migrated to the polyamide surface, and improving the flame retardant effect of polyamide composite films.

[0033] In one optional embodiment, the mass ratio of polyamide in the first polyamide layer, polyamide in the second polyamide layer, chain extender, and flame retardant in this embodiment of the invention is (45-49):(45-49):(0.1-5):(2-10), preferably (45-49):(45-49):(0.1-3):(2-5). It is evident that by using a small amount of flame retardant and chain extender, this embodiment of the invention allows the polyamide in the first and second polyamide layers to react with the flame retardant through the chain extender. This not only prevents the flame retardant, which has poor compatibility with polyamide, from migrating to the polyamide surface despite resistance, but also saves on the amount of flame retardant used. Furthermore, due to the molecular linking between the flame retardant and polyamide, the solid-phase thickening process between the flame retardant and polyamide can be omitted, simplifying the process and saving costs.

[0034] In one optional embodiment, the chain extender of this invention includes at least one selected from oxazoline-based chain extenders, epoxy-functionalized chain extenders, and carbonate-functionalized chain extenders. The general formula for the oxazoline-based chain extender is:

[0035] The general formula for epoxy functionalized chain extenders is: The general formula for carbonate-functionalized chain extenders is:

[0036] In practical applications, the flame-retardant layer of this invention contains a reactive flame retardant, which includes at least one of halogen-free organic flame retardants, phosphorus-based flame retardants, or brominated flame retardants. For example, when the reactive flame retardant is a halogen-free organic flame retardant, it can be 2-carboxyethylphenylphosphonic acid (CEPPA) or its derivatives, or [(6-oxo-6H-dibenzo[c,e][1,2]oxophosphoric acid hexane-6-yl)methyl]succinic acid (DDP) or its derivatives. When the reactive flame retardant is a phosphorus-based flame retardant, it can be a phosphate ester flame retardant or a phosphite ester flame retardant. When the reactive flame retardant is a brominated flame retardant, it can be at least one of 2,3-dibromopropanol, dibromophenol, or tetrabromo-o-dicarboxylic anhydride.

[0037] For example, the structural formula of the above-mentioned 2-carboxyethylphenylphosphonic acid is: The structural formula of the above-mentioned [(6-oxo-6H-dibenzo[c,e][1,2]oxophosphazenecyclo-6-yl)methyl]succinic acid is:

[0038] For example, the polyamide contained in the first polyamide layer and the polyamide contained in the second polyamide layer of the present invention include at least one of the following: a single monomer homopolymer polyamide, a single dimeric homopolymer polyamide, a copolymer polyamide, and a copolymer flame-retardant polyamide. For example, the polyamide includes at least one of polyamide 6, polyamide 66, polyamide 46, polyamide 56, polyamide 10, polyamide 12, polyamide 610, polyamide 612, copolymer flame-retardant polyamide 6, and copolymer flame-retardant polyamide 66zh.

[0039] This invention also provides a method for preparing a polyamide composite film, which can be used to prepare the polyamide composite film of this invention. Figure 2 A schematic flowchart illustrating the preparation method of the polyamide composite film according to an embodiment of the present invention is shown. Figure 2 As shown, the method for preparing the polyamide composite film according to an embodiment of the present invention includes:

[0040] Step 201: Provide a first polyamide layer and form a flame retardant layer on the surface of the first polyamide layer.

[0041] For example, polyamide resin or polyamide copolymer can be melted in an extruder at a temperature of 200°C to 350°C, then extruded through a die and cooled on a quenching roller at a temperature of -200°C to 100°C to form a sheet, i.e., the first polyamide layer. This sheet can be a stretched sheet or a non-stretched sheet. Then, a reactive flame retardant and a chain extender are dissolved in an organic solvent to obtain a mixed solution. This mixed solution is then coated onto the bottom of the first polyamide layer to form a flame-retardant layer. The organic solvent includes at least one of hexafluoroisopropanol, m-cresol, or trifluoroacetic acid.

[0042] In one example, the flame-retardant layer may further include at least one of the following: nucleating agent, matting agent, plasticizer, antistatic agent, heat stabilizer, weather resistant agent, hydrolysis resistant stabilizer, dye, flame retardant, catalyst, defoamer, coupling agent, reinforcing agent, toughening agent, pigment, gloss enhancer, end-capping agent, and UV stabilizer.

[0043] Step 202: Provide a second polyamide layer, forming the second polyimide layer on the surface of the flame retardant layer opposite to the first polyamide layer.

[0044] For example, in an embodiment of the present invention, polyamide resin or polyamide copolymer is melted in an extruder at a temperature of 200°C to 350°C, and then blow-molded to obtain a sheet, namely the second polyamide layer. This sheet can be a stretched sheet or a non-stretched sheet. Then, the second polyamide layer is formed on the surface of the flame-retardant layer opposite to the first polyamide layer.

[0045] Step 203: Under heating conditions, the flame retardant layer is bonded to the surface of the first polyamide layer and the surface of the second polyamide layer to obtain a polyamide composite film.

[0046] For example, the first polyamide layer, the second polyamide layer, and the flame-retardant layer formed therebetween are pre-cut and placed on the frame of a molding machine. The temperature of the upper and lower plates is set to 100℃~350℃, and a certain pressure (0.5MPa~0.6MPa) is maintained for hot pressing. The hot pressing time is 0.5min~5min, preferably 1min~2min, and then placed in a vacuum drying oven for vacuum drying. The temperature of the vacuum drying oven is 100℃~300℃, and the time is 1h~12h. In this embodiment of the invention, a solid-state polymerization reaction is generated by heating the interface between the first and second polyamide layers to prepare a copolymer flame-retardant polyamide composite film. This can reduce the problem of unstable polyamide flowability and film-forming properties caused by secondary feeding during the polyamide film preparation process. At the same time, the flame retardant reacts into the molecular chain of the polyamide, improving the thermal stability of the polyamide composite film.

[0047] As can be seen from the above, the polyamide composite film provided in this embodiment of the invention includes a first polyamide layer, a flame-retardant layer, and a second polyamide layer. The flame-retardant layer is bonded to the surface of the first polyamide layer, and the second polyamide layer is bonded to the surface of the flame-retardant layer facing away from the first polyamide layer. Therefore, the chemical bonds of the first polyamide layer and the second polyamide layer can be connected together through the flame-retardant layer. This prevents thermal motion of the amorphous segments in the polyamide contained in the first and second polyamide layers during long-term use of the polyamide composite film. Consequently, it prevents flame retardants with poor compatibility with polyamide from migrating to the polyamide surface, thus preventing the deterioration of the flame retardants that have precipitated and migrated to the polyamide surface. This improves the flame-retardant effect and safety of the polyamide composite film. Furthermore, in this embodiment of the invention, because the molecular chains of the flame-retardant layer and the polyamide layer are connected, the solid-phase adhesion enhancement process between the flame-retardant layer and the polyamide layer can be omitted, simplifying the process and saving costs.

[0048] As can be seen from the above, the flame retardant in the polyamide composite film provided by the present invention will not precipitate over time, thereby improving the stability of the polyamide composite film and thus improving its safety.

[0049] To verify the effectiveness of the polyamide composite film provided in the embodiments of the present invention, the embodiments of the present invention are demonstrated by comparing the embodiments with comparative examples.

[0050] Example 1

[0051] This invention provides a polyamide composite film, comprising a first polyamide layer, a second polyamide layer, and a flame-retardant layer bonded between the first polyamide layer and the second polyamide layer.

[0052] The method for preparing the polyamide composite film provided in Embodiment 1 of the present invention includes the following steps:

[0053] The first step is to prepare the first polyamide layer: 500g of polyamide resin 66 is melted at 280℃ through an extruder, and then uniformly flows out through a T-die and is cooled on a 30℃ quenching roller to form a sheet, namely the first polyamide layer.

[0054] The second step is to prepare the flame retardant layer: Dissolve 25g of flame retardant CEPPA and 5g of chain extender KL-E4300 in hexafluoroisopropanol and coat it at the bottom of the first polyamide layer to form the flame retardant layer.

[0055] The third step is to prepare the second polyamide layer: 500g of polyamide resin 66 is melted in an extruder at 280℃ and then blown to obtain a sheet, i.e., the second polyamide layer.

[0056] The fourth step is to prepare a polyamide composite film: the surface of the flame-retardant layer away from the first polyamide layer is reacted with the second polyamide layer through a hot-pressing process at a reaction temperature of 260°C, and then placed in a vacuum drying oven at 220°C for 12 hours to obtain a polyamide composite film.

[0057] Example 2

[0058] This invention provides a polyamide composite film, comprising a first polyamide layer, a second polyamide layer, and a flame-retardant layer bonded between the first polyamide layer and the second polyamide layer.

[0059] The method for preparing the polyamide composite film provided in Embodiment 2 of the present invention includes the following steps:

[0060] The first step is to prepare the first polyamide layer: 500g of polyamide resin 66 is melted at 280℃ through an extruder, and then uniformly flows out through a T-die and is cooled on a 30℃ quenching roller to form a sheet, namely the first polyamide layer.

[0061] The second step is to prepare the flame retardant layer: Dissolve 45g of flame retardant CEPPA and 5g of chain extender KL-E4300 in hexafluoroisopropanol and coat it at the bottom of the first polyamide layer to form a flame retardant layer.

[0062] The third step is to prepare the second polyamide layer: 500g of polyamide resin 66 is melted in an extruder at 280℃ and then blown to obtain a sheet, i.e., the second polyamide layer.

[0063] The fourth step is to prepare a polyamide composite film: the surface of the flame-retardant layer away from the first polyamide layer is reacted with the second polyamide layer through a hot-pressing process at a reaction temperature of 260°C, and then placed in a vacuum drying oven at 220°C for 12 hours to obtain a polyamide composite film.

[0064] Example 3

[0065] This invention provides a polyamide composite film, comprising a first polyamide layer, a second polyamide layer, and a flame-retardant layer bonded between the first polyamide layer and the second polyamide layer.

[0066] The method for preparing the polyamide composite film provided in Embodiment 3 of the present invention includes the following steps:

[0067] The first step is to prepare the first polyamide layer: 500g of polyamide resin 66 is melted at 280℃ through an extruder, and then uniformly flows out through a T-die and is cooled on a 30℃ quenching roller to form a sheet, namely the first polyamide layer.

[0068] The second step is to prepare the flame retardant layer: Dissolve 45g of flame retardant DDP-ITA and 5g of chain extender KL-E4300 in hexafluoroisopropanol and coat it at the bottom of the first polyamide layer to form the flame retardant layer.

[0069] The third step is to prepare the second polyamide layer: 500g of polyamide resin 66 is melted in an extruder at 280℃ and then blown to obtain a sheet, i.e., the second polyamide layer.

[0070] The fourth step is to prepare a polyamide composite film: the surface of the flame-retardant layer away from the first polyamide layer is reacted with the second polyamide layer through a hot-pressing process at a reaction temperature of 260°C, and then placed in a vacuum drying oven at 220°C for 12 hours to obtain a polyamide composite film.

[0071] Example 4

[0072] This invention provides a polyamide composite film, comprising a first polyamide layer, a second polyamide layer, and a flame-retardant layer bonded between the first polyamide layer and the second polyamide layer.

[0073] The method for preparing the polyamide composite film provided in Embodiment 4 of the present invention includes the following steps:

[0074] The first step is to prepare the first polyamide layer: 500g of polyamide resin 66 is melted at 280℃ through an extruder, and then uniformly flows out through a T-die and is cooled on a 30℃ quenching roller to form a sheet, namely the first polyamide layer.

[0075] The second step is to prepare the flame retardant layer: Dissolve 45g of flame retardant DDP-ITA and 5g of chain extender BASF Joncryl ADR 4300 in hexafluoroisopropanol and coat it at the bottom of the first polyamide layer to form the flame retardant layer.

[0076] The third step is to prepare the second polyamide layer: 500g of polyamide resin 66 is melted in an extruder at 280℃ and then blown to obtain a sheet, i.e., the second polyamide layer.

[0077] The fourth step is to prepare a polyamide composite film: the surface of the flame-retardant layer away from the first polyamide layer is reacted with the second polyamide layer through a hot-pressing process at a temperature of 300°C, and then placed in a vacuum drying oven at 220°C for 24 hours to obtain a polyamide composite film.

[0078] Example 5

[0079] This invention provides a polyamide composite film, comprising a first polyamide layer, a second polyamide layer, and a flame-retardant layer bonded between the first polyamide layer and the second polyamide layer.

[0080] The method for preparing the polyamide composite film provided in Embodiment 5 of the present invention includes the following steps:

[0081] The first step is to prepare the first polyamide layer: 450g of polyamide resin 6 is melted at 280℃ through an extruder, and then uniformly flows out through a T-die and is cooled on a 30℃ quenching roller to form a sheet, namely the first polyamide layer.

[0082] The second step is to prepare the flame retardant layer: Dissolve 20g of flame retardant DDP and 1g of chain extender tetrabromo-o-dicarboxylic anhydride in trifluoroacetic acid and coat it at the bottom of the first polyamide layer to form the flame retardant layer.

[0083] The third step is to prepare the second polyamide layer: 450g of polyamide resin 46 is melted in an extruder at 280℃ and then blown to obtain a sheet, i.e., the second polyamide layer.

[0084] The fourth step is to prepare a polyamide composite film: the surface of the flame-retardant layer away from the first polyamide layer is reacted with the second polyamide layer through a hot-pressing process at a temperature of 260°C, and then vacuum dried in a vacuum drying oven at 260°C for 15 hours to obtain a polyamide composite film.

[0085] Example 6

[0086] This invention provides a polyamide composite film, comprising a first polyamide layer, a second polyamide layer, and a flame-retardant layer bonded between the first polyamide layer and the second polyamide layer.

[0087] The method for preparing the polyamide composite film provided in Embodiment Six of the present invention includes the following steps:

[0088] The first step is to prepare the first polyamide layer: 500g of polyamide resin 56 is melted at 280℃ through an extruder, and then uniformly flows out through a T-die and is cooled on a 30℃ quenching roller to form a sheet, namely the first polyamide layer.

[0089] The second step is to prepare the flame retardant layer: Dissolve 20g of flame retardant DDP and 5g of chain extender tetrabromo-o-dicarboxylic anhydride in trifluoroacetic acid and coat it at the bottom of the first polyamide layer to form the flame retardant layer.

[0090] The third step is to prepare the second polyamide layer: 480g of polyamide resin 10 is melted in an extruder at 280℃ and then blown to obtain a sheet, i.e., the second polyamide layer.

[0091] The fourth step is to prepare a polyamide composite film: the surface of the flame-retardant layer away from the first polyamide layer is reacted with the second polyamide layer through a hot-pressing process at a temperature of 260°C, and then vacuum dried in a vacuum drying oven at 260°C for 15 hours to obtain a polyamide composite film.

[0092] Comparative Example 1

[0093] The present invention provides a polyamide composite film in a comparative example, comprising a first polyamide layer and a second polyamide layer, but without the flame retardant layer of the embodiments of the present invention.

[0094] The method for preparing the polyamide composite film provided in Comparative Example 1 of the present invention includes the following steps:

[0095] The first step is to prepare the first polyamide layer: 500g of polyamide resin 66 is melted at 280℃ through an extruder, and then uniformly flows out through a T-die and is cooled on a 30℃ quenching roller to form a sheet, namely the first polyamide layer.

[0096] The second step is to prepare the second polyamide layer: 500g of polyamide resin 66 is melted in an extruder at 280℃ and then blown to obtain a sheet, i.e., the second polyamide layer.

[0097] The third step is to prepare a polyamide composite film: the first polyamide layer and the second polyamide layer are reacted by hot pressing at a temperature of 260°C, and then vacuum dried in a vacuum drying oven at 220°C for 12 hours to obtain a polyamide composite film.

[0098] Comparative Example 2

[0099] The present invention provides a polyamide film in a comparative example, comprising polyamide resin, flame retardant and chain extender.

[0100] The method for preparing the polyamide film provided in Comparative Example 2 of the present invention includes the following steps:

[0101] Polyamide resin 66, 50g of flame retardant CEPPA, and 50g of chain extender KL-E4300 were melted in an extruder at 280℃, and then uniformly flowed out through a T-die and cooled on a 30℃ quenching roller to form a 500g sheet. The sheet was then placed in a 220℃ vacuum drying oven and vacuum dried for 12 hours to obtain a polyamide film.

[0102] The limiting oxygen index, UL-94, and melt drop properties of the polyamide composite films prepared in the examples and comparative examples of this invention are tested using the following methods:

[0103] Limiting oxygen index (LOI) test: The test was conducted at room temperature using a limiting oxygen index tester, in accordance with ASTM D2863-2010 standard, "Determination of flammability of plastics by oxygen index method".

[0104] UL-94 Vertical Burning Test: Refer to DIN IEC 60695-11-10-20 "Test Methods for Burning Performance of Plastics - Horizontal and Vertical Methods" standard.

[0105] In the embodiments and comparative examples of this invention, Examples 1 to 6 all prepared polyamide composite films containing flame-retardant layers. Comparative Example 1, compared with the embodiments of this invention, does not contain the flame-retardant layer of the embodiments of this invention, and Comparative Example 2 is not a composite film. The test results of the embodiments and comparative examples are shown in the table below:

[0106]

[0107] As can be seen from the table above, the polyamide composite films prepared in Examples 1 to 6 of the present invention include a first polyamide layer, a second polyamide layer, and a flame-retardant layer bonded between the first and second polyamide layers. The polyamide composite film prepared in Comparative Example 1 does not contain the flame-retardant layer of the present invention, but only contains two polyamide layers, while Comparative Example 2 contains only one polyamide layer. The oxygen index of Examples 1 to 6 is significantly higher than that of Comparative Example 1 and Comparative Example 2. The UL-94 of Examples 1 to 6 is V-0, meaning that after two 10-second burning tests on the polyamide composite film samples of Examples 1 to 6, the flame can be extinguished within 10 seconds. Therefore, in the polyamide composite films prepared in Examples 1 to 6 of the present invention, the flame retardant layer can be bonded to the surface of the first polyamide layer and the second polyamide layer can be bonded to the surface of the flame retardant layer away from the first polyamide layer under the hot pressing process. At this time, the chemical bonds of the first polyamide layer and the second polyamide layer can be connected together through the flame retardant layer. Thus, when the polyamide composite film is used for a long time, the amorphous segments in the polyamide contained in the first polyamide layer and the polyamide contained in the second polyamide layer can be prevented from undergoing thermal motion. This prevents flame retardants with poor compatibility with polyamide from migrating to the polyamide surface by overcoming resistance, thereby preventing the flame retardants that precipitate and migrate to the polyamide surface from deteriorating. This improves the flame retardant effect and enhances the safety of the polyamide composite film.

[0108] The above description is merely a specific embodiment of the present invention. Obviously, various modifications and combinations can be made without departing from the spirit and scope of the present invention. Accordingly, this specification and accompanying drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the present invention. Clearly, those skilled in the art can make various alterations and modifications to the present invention without departing from its spirit and scope. Thus, if these modifications and variations of the present invention fall within the scope of the claims and their equivalents, the intent of the present invention includes these modifications and variations. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the claims.

Claims

1. A polyamide composite film, characterized in that, It includes a first polyamide layer, a flame retardant layer, and a second polyamide layer, wherein the flame retardant layer is bonded to the surface of the first polyamide layer, and the second polyamide layer is bonded to the surface of the flame retardant layer opposite to the first polyamide layer; The flame retardant layer contains a chain extender and a flame retardant. The flame retardant is grafted onto the polyamide contained in the first polyamide layer through the chain extender. The polyamide contained in the second polyamide layer is grafted onto the surface of the flame retardant layer opposite to the first polyamide layer through the chain extender. The mass ratio of polyamide in the first polyamide layer, polyamide in the second polyamide layer, chain extender and flame retardant is (45~49):(45~49):(0.1~5):(2~10).

2. The polyamide composite film according to claim 1, characterized in that, The chain extender includes at least one of oxazoline chain extenders, epoxy-functionalized chain extenders, and carbonate-functionalized chain extenders.

3. The polyamide composite film according to any one of claims 1 to 2, characterized in that, The flame-retardant layer contains a reactive flame retardant, which includes at least one of halogen-free organic flame retardants or brominated flame retardants.

4. The polyamide composite film according to any one of claims 1 to 2, characterized in that, The polyamide contained in the first polyamide layer and the polyamide contained in the second polyamide layer include at least one of the following: single monomer homopolymer polyamide, single diene homopolymer polyamide, copolymer polyamide, and copolymer flame retardant polyamide.

5. A method for preparing a polyamide composite film according to any one of claims 1 to 4, characterized in that, include: A first polyamide layer is provided, and a flame-retardant layer is formed on the surface of the first polyamide layer; A second polyamide layer is provided, which is formed on the surface of the flame-retardant layer opposite to the first polyamide layer; Under heating conditions, the flame-retardant layer is bonded to the surface of the first polyamide layer and the surface of the second polyamide layer to obtain a polyamide composite film.

6. The method for preparing the polyamide composite film according to claim 5, characterized in that, Before forming a flame-retardant layer on the surface of the first polyamide layer, the method further includes: A flame retardant layer is obtained by dissolving a flame retardant and a chain extender in an organic solvent and coating it onto the surface of a first polyamide layer. The organic solvent includes at least one of hexafluoroisopropanol, m-cresol, or trifluoroacetic acid.

7. The method for preparing the polyamide composite film according to claim 5, characterized in that, The heating conditions are as follows: the heating temperature is 100℃~350℃, and the heating time is 0.5min~5min.

8. An electronic device that uses the polyamide composite film according to any one of claims 1 to 4.

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