Method for manufacturing a liquid crystal polymer film and liquid crystal polymer film

Abstract

This application relates to a method for manufacturing a liquid crystal polymer film and a liquid crystal polymer film, which includes the following steps: thermally compounding a primary film of a liquid crystal polymer with a support to obtain a laminate; heating the laminate obtained by thermal compounding under the protection of an inert gas, and after heat preservation treatment at the first temperature T a for a preset time, cooling to the second temperature T b or below; then, within the third temperature T t , performing a gradient heating treatment from T1 to T n ; finally, peeling off the support in the laminate obtained after treatment to obtain a treated liquid crystal polymer film. Compared with the prior art, this application can obtain a liquid crystal polymer film that simultaneously has good elongation at break, wear resistance, and heat resistance.

Description

Technical Field

[0001] The present application relates to the field of liquid crystal polymers, and particularly to a method for manufacturing a liquid crystal polymer film and a liquid crystal polymer film. Background Art

[0002] Due to its unique properties such as low dielectric properties, high heat resistance, low moisture absorption, and excellent dimensional stability, liquid crystal polymer (LCP) materials are considered ideal substrates for 5G radio frequency antennas and are widely used in the field of electronic communications.

[0003] In the prior art, the blow molding method is generally used to manufacture LCP films. Through transverse blowing and longitudinal stretching, the prepared LCP primary film can achieve a good balance of mechanical properties in the machine direction (MD) and the transverse direction perpendicular to the machine direction (TD). However, the prepared LCP primary film still has problems such as poor surface abrasion resistance (easy to fuzz due to friction), obvious microscopic layered structure (easy to cause skin-core separation and affect the bonding force with copper foil), low elongation at break, and insufficient heat resistance, making it unable to be directly used as an insulating substrate on devices such as flexible printed circuits (PCs). To improve the above-mentioned performance defects, the prior art mainly adopts the method of heat-treating the LCP primary film. For example, as disclosed in Patent CN110760310: heating the LCP primary film to 250°C at a lower heating and cooling rate and then performing heat preservation treatment for 6 hours can improve the brittleness of the LCP film. Another example is the content disclosed in Patent CN1232860: adopting gradient heating heat treatment starting from a temperature below T m (the critical temperature from solid to liquid, melting point temperature) can improve the surface abrasion resistance and heat resistance of the LCP film.

[0004] However, in practical applications, after heat-treating the LCP primary film in the above-mentioned manner, although the heat resistance of the LCP primary film can be improved, the elongation at break cannot be significantly improved and the microscopic layered structure cannot be eliminated.

[0005] To improve the elongation at break of the material, Patent US5529740 discloses a method of performing heat treatment at a temperature of T m + 20°C and above for 2 - 10 minutes to improve the elongation at break, abrasion resistance, and eliminate the microscopic layered structure of the LCP film. However, the defect of this method is that the heat resistance of the prepared LCP film is still poor.

[0006] Therefore, how to provide a method for manufacturing an LCP film and an LCP film so that the manufactured LCP film has good elongation at break, abrasion resistance, and heat resistance at the same time is a technical problem that the present application urgently needs to solve. Summary of the Invention

[0007] The purpose of the present application is to provide a method for manufacturing a liquid crystal polymer film and a liquid crystal polymer film, so that the LCP film has good characteristics such as elongation at break, wear resistance, and heat resistance at the same time.

[0008] To achieve the above object, the present application proposes a method for manufacturing a liquid crystal polymer film, including the following steps:

[0009] A method for manufacturing a liquid crystal polymer film, including the following steps:

[0010] (1) Thermally compound the primary film of the liquid crystal polymer with a support to obtain a laminate;

[0011] (2) The laminate obtained in step (1) is subjected to a temperature increase treatment under the protection of an inert gas, and after being heat-insulated at the first temperature T a for a preset time, it is cooled to a second temperature T b or lower. Among them, (T m + 10 °C) ≤ T a ≤ (T m + 60 °C), T m is the melting peak temperature of the primary film, T b ≤ (T c - 10 °C), T c is the crystallization peak temperature of the primary film during the cooling process;

[0012] (3) The laminate processed in step (2) is subjected to a gradient temperature increase treatment within the third temperature T t from T1 to T n , where T t is (T m - 40 °C) to (T m + 10 °C), T n is the heat treatment temperature in the gradient temperature increase treatment, T n-1 ≤ T n ≤ (T0 - 10 °C), n is the number of stages and is greater than or equal to 2, T o The temperature is the melting start temperature of the liquid crystal polymer layer in the laminate after being heat-treated at T n-1 ;

[0013] (4) Peel off the support in the laminate processed in step (3) to obtain a liquid crystal polymer film.

[0014] Further preferably, T a can also be preferably T m + 15 °C, T m + 20 °C, T m + 25 °C, T m + 30 °C, Tm +40 °C, or T m +50 °C, etc.

[0015] Further preferably, (T m +15 °C) ≤ T a ≤ (T m +50 °C).

[0016] Further preferably, T b ≤ (T c -20 °C).

[0017] Further preferably, T b can preferably be T c -10 °C, T c -11 °C, T c -15 °C, etc.

[0018] Optionally, the heating rate during the heating treatment in step S2 is 5 - 40 °C / min;

[0019] Further preferably, the heating rate during the heating treatment in S2 is 10 - 30 °C / min.

[0020] Further preferably, the preset time is 1 - 20 min.

[0021] Further preferably, the T n is a constant temperature or a variable temperature.

[0022] Further preferably, the preset period of the gradient heating heat treatment is at least 3 h.

[0023] Further preferably, the preset period is 3 - 24 h;

[0024] and / or, the time for each stage of heating treatment is 0.5 - 4 h;

[0025] and / or, the n is 2 - 10.

[0026] Further preferably, the attachment layer is a metal foil layer;

[0027] and / or, the thickness of the attachment layer is 30 - 100 μm;

[0028] and / or, the surface roughness of the attachment layer is less than 0.3 μm.

[0029] Further preferably, the composite method of the primary film and the support is single-sided composite or double-sided composite.

[0030] Further preferably, the metal foil of the adhering layer is any one of copper foil, stainless steel foil, aluminum foil or a combination thereof.

[0031] Further preferably, the heating method for the heat treatment is any one of infrared lamp tubes, far-infrared radiation heating plates, hot air or heat-conducting oil or a combination thereof.

[0032] Further preferably, the inert gas is nitrogen.

[0033] Further preferably, the oxygen content requirement under the protection of the inert gas is less than 1000 ppm.

[0034] Further preferably, the primary film of the liquid crystal polymer is prepared by the blown film method.

[0035] Further preferably, before the step of peeling the support in the laminate to obtain the liquid crystal polymer film, the laminate is cooled to room temperature.

[0036] This application also provides a liquid crystal polymer film prepared by the above manufacturing method of the liquid crystal polymer film.

[0037] Further preferably, the tensile strength of the liquid crystal polymer film in the horizontal mechanical direction is 169 MPa or more;

[0038] and / or, the tensile strength of the liquid crystal polymer film in the vertical mechanical direction is 153 MPa or more;

[0039] and / or, the elongation at break of the liquid crystal polymer film in the horizontal mechanical direction is 24% or more;

[0040] and / or, the elongation at break of the liquid crystal polymer film in the vertical mechanical direction is 26% or more;

[0041] and / or, the heat distortion temperature of the liquid crystal polymer film is 269 °C or more.

[0042] Further preferably, the tensile strength of the liquid crystal polymer film in the horizontal mechanical direction is 169 MPa to 182 MPa;

[0043] Further preferably, the tensile strength of the liquid crystal polymer film in the vertical mechanical direction is 153 MPa to 158 MPa;

[0044] Further preferably, the elongation at break of the liquid crystal polymer film in the horizontal mechanical direction is 24% to 34%;

[0045] Further preferably, the elongation at break of the liquid crystal polymer film in the direction perpendicular to the mechanical direction is 26% - 32%.

[0046] Compared with the prior art, the beneficial effects of the present application are mainly reflected in that the liquid crystal polymer film prepared by the above method can endow the manufactured liquid crystal polymer film with good elongation at break, wear resistance, heat resistance and other characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the heat treatment process of the LCP film in Embodiment 1 of the present application;

[0048] Figure 2 It is a DSC diagram of the as - cast LCP film in Comparative Example 1 of the present application;

[0049] Figure 3 It is a microscopic morphology diagram of the brittle fracture surface of the LCP film in Embodiment 1 of the present application;

[0050] Figure 4 It is a microscopic morphology diagram of the brittle fracture surface of the LCP film in Embodiment 2 of the present application;

[0051] Figure 5 It is a microscopic morphology diagram of the brittle fracture surface of the LCP film in Embodiment 3 of the present application;

[0052] Figure 6 It is a microscopic morphology diagram of the brittle fracture surface of the LCP film in Comparative Example 1 of the present application;

[0053] Figure 7 is T n It is a schematic diagram of the heat treatment process of the variable - temperature temperature program. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] The manufacturing method of the liquid crystal polymer film of the present application will be described in more detail below with reference to the schematic diagrams. The preferred embodiments of the present application are shown, and it should be understood that those skilled in the art can modify the present application described herein while still achieving the beneficial effects of the present application. Therefore, the following description should be understood as broad guidance for those skilled in the art and not as a limitation to the present application.

[0055] Embodiment 1

[0056] This Embodiment 1 provides a manufacturing method of a liquid crystal polymer film, including the following steps:

[0057] Step S1: Thermally compound the as - cast film of the liquid crystal polymer with a support to obtain a laminate;

[0058] Step S2: Heat the laminate obtained in Step S1 under the protection of an inert gas and at the first temperature Ta After the preset time of the lower heat preservation treatment, the temperature is reduced to the second temperature T b as follows. Wherein, (T m + 10 °C) ≤ T a ≤ (T m + 60 °C), T m is the melting peak temperature of the as - formed film, and T b ≤ (T c - 10 °C), T c is the crystallization peak temperature of the material forming the as - formed film during the cooling process.

[0059] In addition, it is worth mentioning that, as a preferred method, T m in this embodiment is preferably 280 °C, and T c is preferably 240 °C. Only this is taken as an example for illustration, without further specific limitation and elaboration.

[0060] Step S3: Under the protection of an inert gas, the laminate obtained through Step S2 is subjected to a gradient heating treatment within the third temperature T t from T1 to T n . Wherein, T t is (T m - 40 °C) to (T m + 10 °C), T n is the heat treatment temperature in the gradient heating treatment, T n-1 ≤ T n ≤ (T0 - 10 °C), n is the number of stages and is greater than or equal to 2, and T o is the melting start temperature of the liquid crystal polymer layer in the laminate after the heat treatment with T n-1 ;

[0061] Step S4: The support in the laminate obtained through Step S3 is peeled off to obtain a liquid crystal polymer thin film.

[0062] It can be seen from the above steps that: in this application, by performing high - temperature short - time heat treatment, temperature reduction, and gradient heating long - time heat treatment on the laminate formed by the composite of the LCP as - formed film and the support, and reasonably controlling the heating rate and the degree of temperature reduction, the liquid crystal polymer thin film peeled off after the heat treatment has excellent wear resistance, a greatly increased elongation at break, excellent heat resistance, and can preferably eliminate the lamellar microstructure in the film.

[0063] In addition, during the process of first heating and then cooling the laminate, the oxygen content under the protection of the inert gas is controlled below 1000 ppm, and the first temperature T a is controlled within (T m + 10 °C) to (T mWithin (+60°C), it can not only avoid the insignificant increase in the elongation at break of the LCP film and the unclear elimination of the lamellar structure in the film due to too low temperature, but also avoid the easy deterioration and degradation of the LCP film in the laminate or the difficulty in separation due to adhesion to the support due to too high temperature.

[0064] Optionally, the above-mentioned T n is the constant temperature, where n represents the number of stages, that is, the number of times of the gradient heating stage, and n can be preferably three or five or ten, or more times, etc.

[0065] As another alternative way, as Figure 7 shown, at least part of the above-mentioned T n is the variable temperature, and no specific limitation and elaboration will be made here.

[0066] Optionally, in the above step S1, the laminate is heated to the first temperature T a , that is, within the range of (T m +10°C) ≤ T a ≤ (T m +60°C), where T a can be preferably (T m +15°C) ~ (T m +50°C).

[0067] Optionally, the primary film of the above liquid crystal polymer is prepared by the blown film method.

[0068] In the above step S2, after heat preservation treatment for a preset time at the first temperature T a , it is cooled to the second temperature T b or below, that is, T b ≤ (T c -10°C), in the process of obtaining the laminate, T b can be preferably T c -10°C, T c -11°C, T c -15°C, etc.

[0069] As a further preference, the above T b ≤ (T c -20°C), for example, T b is preferably T c -20°C, T c -30°C, T c -40°C, etc., so as to ensure that the LCP film in the laminate can be fully cooled and crystallized, making the crystallized region formed in this stage conducive to the subsequent multi-step gradient heating heat treatment, thereby promoting the growth and perfection of crystals / crystalline regions in the gradient heating heat treatment process, and thus improving the heat resistance.

[0070] Optionally, in the above step S2, the heating rate during the above heating process is 5 - 40 °C / min. For example, 5 °C / min, 10 °C / min, 15 °C / min, 20 °C / min, 25 °C / min, 30 °C / min, 35 °C / min, 40 °C / min, etc. With this heating rate, it is possible to avoid an obvious thermal history during the slow heating process due to too small a heating rate, resulting in an insignificant increase in the elongation at break of the LCP film and an insignificant elimination of the microscopic layered structure, etc., and to avoid the generation of bubbling on the film surface due to uneven rapid heating caused by too fast a heating rate, thereby obtaining a better heat treatment effect.

[0071] Further optionally, the heating rate during the above heating process is preferably 10 - 30 °C / min.

[0072] Optionally, in the above step S2, the first temperature T a The preset time for heat preservation treatment is 1 - 20 min, for example, preferably 5 min, 10 min, 15 min, etc.

[0073] Optionally, in the above step S3, the above laminate is heated to the third temperature T t , and the preset period for multi-stage gradient heating heat treatment is at least 3 h, for example, 3 h - 24 h.

[0074] And, as a better way, the heating time for each stage of the above heating treatment is 0.5 - 4 h, for example, 0.5 h, 1 h, 2 h, etc. By performing staged heating treatment on the laminate, it is possible to better form the liquid crystal film layer in the laminate and promote the growth of crystals / crystalline regions, thereby gradually improving the heat resistance (melting point) of the film. And by extending the heat treatment time for each stage in the gradient heating stage and ensuring that the heat treatment temperature T n in the nth step of the subsequent step is greater than T n-1 , and at the same time less than T c - 10 °C. Compared with the heat treatment method at a single temperature, it is easier to form crystal regions, and during the gradual heating process, it promotes the growth and expansion of crystal regions, and further can make the heat resistance (melting point) of the film reach a specific value in a shorter time.

[0075] Optionally, the above support is a metal foil, such as any one of or a combination of copper foil, stainless steel foil, and aluminum foil.

[0076] Optionally, the thickness of the above support is 30 - 100 μm to meet the actual process and production requirements and save costs.

[0077] Optionally, the surface roughness Ra of the above-mentioned support is less than 0.3 μm to avoid excessive surface roughness, which may lead to too strong bonding force between the liquid crystal polymer and the support in the heat-treated laminate, making it difficult to separate and resulting in local damage or deformation that affects the mechanical properties.

[0078] Optionally, the heating method for the above heat treatment is any one or a combination of infrared lamp tubes, far-infrared radiation heating plates, hot air, or heat-conducting oil.

[0079] There is no special limitation on the inert gas in this embodiment, as long as it does not react with the LCP film. Generally, at least one of nitrogen, helium, and argon is used.

[0080] Optionally, the oxygen content requirement under the protection of the above inert gas is less than 1000 ppm to prevent the liquid crystal polymer film from thermal deterioration and yellowing due to excessive oxygen content.

[0081] The LCP primary film in this embodiment method is all self-made by the blown film method. Among them, the blow-up ratio in the blown film process is 6.4, and the draw ratio is 3.1; the thickness of the primary film is 40 μm, and the melting point of the raw material used to prepare the primary film is 280 °C, as Figure 2 shown.

[0082] The following is combined with the embodiments of the present application for the purpose of explaining the present application, and should not be construed as a limitation of the present application.

[0083] Example 1

[0084] This embodiment provides a method for manufacturing an LCP film, which includes the following steps:

[0085] Step S1: Thermally laminate the LCP primary film with an aluminum foil having a thickness of 40 μm and a surface roughness Ra of 0.21 μm through a hot roller to obtain a single-sided laminate;

[0086] Step S2: Place the single-sided laminate obtained in Step S1 in a hot air drying oven under the protection of an inert gas, heat it to 320 °C at a heating rate of 10 °C / min, hold for 5 min, and then cool to 220 °C;

[0087] Step S3: Continue to heat the single-sided laminate treated in Step S2 to 250 °C and hold for 3 h, heat to 260 °C and hold for 3 h, heat to 270 °C and hold for 3 h, and then heat to 275 °C and hold for 2 h;

[0088] Step S4: Peel off the support in the single-sided laminate treated in Step S3 to obtain the LCP film.

[0089] Example 2

[0090] This embodiment provides a method for manufacturing an LCP film, which includes the following steps:

[0091] Step S1: Thermally laminate the LCP virgin film with an aluminum foil having a thickness of 40 μm and a surface roughness Ra of 0.21 μm through a hot roll to obtain a single-sided laminate;

[0092] Step S2: Place the single-sided laminate obtained in Step S1 in a hot air drying oven under the protection of an inert gas, heat it to 320 °C at a heating rate of 10 °C / min, hold for 5 min, and then cool it to 220 °C;

[0093] Step S3: Continuously heat the single-sided laminate after being treated in Step S2 to 260 °C and hold for 3 h, heat to 270 °C and hold for 3 h, heat to 275 °C and hold for 3 h, and then heat to 280 °C and hold for 2 h;

[0094] Step S4: Peel off the support in the single-sided laminate after being treated in Step S3 to obtain the LCP film.

[0095] Example Three

[0096] This embodiment provides a method for manufacturing an LCP film, which includes the following steps:

[0097] Step S1: Thermally laminate the LCP virgin film with an aluminum foil having a thickness of 40 μm and a surface roughness Ra of 0.21 μm through a hot roll to obtain a single-sided laminate;

[0098] Step S2: Place the single-sided laminate obtained in Step S1 in a hot air drying oven under the protection of an inert gas, heat it to 300 °C at a heating rate of 10 °C / min, hold for 5 min, and then cool it to 210 °C;

[0099] Step S3: Continuously heat the single-sided laminate after being treated in Step S2 to 250 °C and hold for 3 h, heat to 260 °C and hold for 3 h, heat to 270 °C and hold for 3 h, and then heat to 275 °C and hold for 2 h;

[0100] Step S4: Peel off the support in the single-sided laminate after being treated in Step S3 to obtain the LCP film.

[0101] Example Four

[0102] This embodiment provides a method for manufacturing an LCP film, which includes the following steps:

[0103] Step S1: Thermally laminate the LCP virgin film with a stainless steel foil having a thickness of 50 μm and a surface roughness Ra of 0.25 μm through a hot press to obtain a double-sided laminate;

[0104] Step S2: Place the double-sided laminate after being processed in Step S1 in a hot air drying oven under the protection of an inert gas, heat it up to 320°C at a heating rate of 10°C / min, hold for 5 min, and then cool it down to 220°C;

[0105] Step S3: Continue to heat the double-sided laminate after being processed in Step S2 to 250°C and hold for 3 h, then heat it to 260°C and hold for 3 h, then heat it to 270°C and hold for 3 h, and then heat it to 275°C and hold for 2 h;

[0106] Step S4: Peel off the support in the double-sided laminate after being processed in Step S3 to obtain an LCP film.

[0107] Comparative Example 1

[0108] This comparative example provides an LCP film, which is an LCP virgin film, that is, the LCP virgin film used in the above Examples 1 to 3.

[0109] Comparative Example 2

[0110] This comparative example provides a method for manufacturing an LCP film, which includes the following steps:

[0111] Step S1: Thermally laminate an LCP virgin film with an aluminum foil having a thickness of 40 μm and a surface roughness Ra of 0.21 μm through a hot roll to obtain a single-sided laminate;

[0112] Step S2: Place the single-sided laminate obtained in Step S1 in a hot air drying oven under the protection of an inert gas, heat it up to 320°C at a heating rate of 10°C / min, hold for 5 min, and then cool it to room temperature;

[0113] Step S3: Peel off the support in the single-sided laminate after being processed in Step S2 to obtain an LCP film.

[0114] Comparative Example 3

[0115] This comparative example provides a method for manufacturing an LCP film, which includes the following steps:

[0116] Step S1: Thermally laminate an LCP virgin film with an aluminum foil having a thickness of 40 μm and a surface roughness Ra of 0.21 μm through a hot roll to obtain a single-sided laminate;

[0117] Step S2: Place the single-sided laminate after being processed in Step S1 in a hot air drying oven under the protection of an inert gas, heat it up to 250°C at a heating rate of 10°C / min and hold for 3 h, then heat it to 260°C and hold for 3 h, then heat it to 270°C and hold for 3 h, and then heat it to 275°C and hold for 2 h, and then cool it to room temperature

[0118] Step S3: Peel off the support in the single-layer laminate after being processed in Step S2 to obtain an LCP film.

[0119] Comparative Example 4

[0120] This comparative example provides a method for manufacturing an LCP film, which includes the following steps:

[0121] Step S1: Thermally laminate an LCP virgin film and an aluminum foil with a thickness of 40 μm and a surface roughness Ra of 0.21 μm through a hot roller to obtain a single-layer laminate.

[0122] Step S2: Place the single-layer laminate after being processed in Step S1 in a hot air drying oven under the protection of an inert gas, heat it to 320 °C at a heating rate of 10 °C / min, hold for 5 min, and then cool it to 260 °C.

[0123] Step S3: Keep the single-layer laminate after being processed in Step S2 at 260 °C for 3 h, heat it to 270 °C and hold for 3 h, heat it to 275 °C and hold for 3 h, and then heat it to 280 °C and hold for 2 h.

[0124] Step S4: Peel off the support in the single-layer laminate after being processed in Step S3 to obtain an LCP film.

[0125] Embodiment 2

[0126] This Embodiment 2 provides a liquid crystal polymer film, which is prepared by the method for manufacturing a liquid crystal polymer film provided in the above Embodiment 1.

[0127] The present invention carried out the following performance tests on the above-mentioned examples and comparative examples.

[0128] The test methods for the examples and comparative examples are as follows:

[0129] 1. Mechanical property test: According to ASTM D882, the test instrument is an INSTRON 5965 type electronic universal tensile testing machine. The size of the cut test specimen is 100 mm × 10 mm, the fixture spacing is 50 mm, the tensile rate is 25 mm / min, and the tensile strength and elongation at break are tested and recorded.

[0130] 2. Melting point test: According to GB / T 19466.3-2004, the test instrument is a DSC 250 type differential scanning calorimeter. Under the protection of nitrogen, the sample is heated from 25 °C to 330 °C at a heating rate of 10 °C / min, and the peak value of the melting peak is recorded as the melting point T m , and the temperature at the starting position of the melting peak is recorded as the starting melting temperature T o .

[0131] 3. Heat distortion temperature test: According to GB / T1634.2-2019, the test instrument is a TMA450 type thermomechanical analyzer. A 1 g load is applied to a test sample with a width of 5 mm and a length of 20 mm, and then the temperature is raised to 310 °C at a heating rate of 10 °C / min to obtain a temperature-dimension change rate curve. The intersection point of the tangents of the curve before and after the sudden change of the dimension change rate is called the heat distortion temperature.

[0132] 4. Scanning electron microscope (SEM) test: The test instrument is an EVOMA10 type scanning electron microscope. The LCP film is brittle fractured along the transverse direction (TD) under liquid nitrogen conditions, and the brittle fracture surface is obtained under high vacuum conditions at a voltage of 4.0 kV. After spraying with gold, the surface microstructure layer structure is observed.

[0133] 5. Abrasion resistance test: A square block with a bottom surface of 10 mm × 15 mm covered with a fabric cloth is placed on the surface of the liquid crystal polymer film, and a 500 g weight is loaded on the block. Then, it reciprocates 30 mm on the LCP film surface. After continuous movement for 1 h, the change of the LCP film surface is observed. The case where a large number of fibrils are generated is evaluated as poor abrasion resistance, the case where no fibrils are generated is evaluated as excellent abrasion resistance, and the intermediate case is evaluated as medium abrasion resistance.

[0134] The test results of the examples and comparative examples are as follows:

[0135] Table 1 Performance test results of the LCP films prepared in the examples and comparative examples

[0136]

[0137] Table 2 Comparative schematic of the LCP films in the heat treatment stage in the examples and comparative examples Figure 1

[0138]

[0139] Table 3 Comparative schematic of the LCP films in the heat treatment stage in the examples and comparative examples Figure 2

[0140]

[0141] Analysis of the test results of the LCP films corresponding to Examples 1-4 and Comparative Examples 1-4 tabulated in Tables 1 to 3: The tensile strength of the LCP film prepared by the method provided in this application can reach over 169 MPa in the machine direction (MD) horizontally and over 153 MPa in the transverse direction (TD) vertically; the elongation at break can reach over 24.4% in the machine direction (MD) horizontally and over 26.5% in the transverse direction (TD) vertically; the heat distortion temperature of the LCP film is over 269 °C.

[0142] In addition, as can be seen from Comparative Example 4 and Table 1, there are two melting point peaks in the DSC test results of the LCP film prepared in Comparative Example 4, which is caused by the inappropriate selection of the cooling temperature. That is to say, the prepared finished film has defects such as poor heat resistance stability.

[0143] In addition, from the Figures 3 to 6 fracture surface morphology diagrams of the LCP films provided in the examples and comparative examples, it can also be seen that the LCP film prepared by the method provided in this application can better eliminate the internal microscopic layered structure of the film, thereby better improving its elongation at break.

[0144] Thus, it can be seen that the LCP film prepared by the above steps has excellent elongation at break, heat resistance, wear resistance and other advantages.

[0145] The above are only the preferred embodiments of this application and do not impose any limitation on this application. Any person skilled in the art, without departing from the technical solution of this application, makes any form of equivalent replacement or modification and other changes to the technical solution and technical content disclosed in this application, all of which fall within the content of the technical solution of this application and are still within the protection scope of this application.

Claims

1. A method for manufacturing a liquid crystal polymer thin film, characterized in that, It includes the following steps: (1) Thermally compound the primary film of liquid crystal polymer with a support to obtain a laminate; (2) Heat the laminate obtained in step (1) under the protection of an inert gas, and after heat preservation at the first temperature T a for a preset time, cool down to the second temperature T b hereinafter, where (T m + 10 °C) ≤ T a ≤ (T m + 60 °C), T m is the melting peak temperature of the nascent film, T b ≤ (T c - 10 °C), T c is the crystallization peak temperature of the nascent film during the cooling process; among them, the preset time for heat preservation at the first temperature T a is 1 to 20 min, and the heating rate during the heating process is 5 - 40 °C / min; (3) The laminated body treated in step (2) is heated at a third temperature T under the protection of an inert gas. t Within, perform T1~T n Gradient heating treatment, where T t is (T m -40℃)~(T m +10℃), T n is the heat treatment temperature in the gradient heating treatment, T n-1 ≤T n ≤(T0-10℃), n is the number of stages and is greater than or equal to 2, T o Temperature is T n-1 The melting starting temperature of the liquid crystal polymer layer in the laminate after heat treatment; (4) After peeling off the support in the laminate processed in step (3), a liquid crystal polymer thin film is obtained.

2. The manufacturing method of the liquid crystal polymer thin film according to claim 1, wherein The primary film of the liquid crystal polymer is prepared by the blown film method.

3. The manufacturing method of the liquid crystal polymer thin film according to claim 1, characterized in that The support is a metal foil; and / or, the metal foil is any one or a combination of copper foil, stainless steel foil, and aluminum foil; and / or, the thickness of the support is 30 - 100 μm; and / or, the surface roughness of the support is less than 0.3 μm.

4. The manufacturing method of the liquid crystal polymer thin film according to claim 1, characterized in that, In step (1), the compounding method of the primary film and the support is single-sided compounding or double-sided compounding.

5. The manufacturing method of the liquid crystal polymer thin film according to claim 1, characterized in that, In step (3), the preset period of the gradient heating treatment is 3 - 24 h; The heating time for each stage is 0.5 - 4 h; and / or, the n is 2 - 10; and / or, the heating rate during the heating treatment is 10 - 30 °C / min.

6. The manufacturing method of the liquid crystal polymer thin film according to claim 1, characterized in that, The heating method of the heat treatment is any one or a combination of infrared lamp tubes, far-infrared radiation heating plates, hot air, and heat transfer oil.

7. The manufacturing method of the liquid crystal polymer thin film according to claim 1, characterized in that, During the heating and heat preservation processes, the oxygen content requirement under the protection of inert gas is less than 1000 ppm.

8. A liquid crystal polymer film, characterized in that, It is prepared by the manufacturing method of the liquid crystal polymer thin film according to any one of claims 1 to 7.

9. The liquid crystal polymer thin film according to claim 8, wherein the tensile strength of the liquid crystal polymer thin film in the horizontal mechanical direction is 169 MPa or more; and / or, the tensile strength of the liquid crystal polymer thin film in the vertical mechanical direction is 153 MPa or more; and / or, the elongation at break of the liquid crystal polymer thin film in the horizontal mechanical direction is 24% or more; and / or, the elongation at break of the liquid crystal polymer thin film in the vertical mechanical direction is 26% or more; and / or, the heat distortion temperature of the liquid crystal polymer thin film is 269 °C or more.

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