Manufacturing method of liquid crystal polymer film and liquid crystal polymer film

Abstract

The invention relates to a manufacturing method of a liquid crystal polymer film and the liquid crystal polymer film, and the manufacturing method comprises the following steps: thermally compounding a primary film of a liquid crystal polymer and a support body to obtain a laminated body; carrying out heating treatment on a laminated body obtained by thermal compounding under the protection of inert gas, carrying out heat preservation treatment at a first temperature Ta for a preset time, and cooling to a temperature below a second temperature Tb; carrying out gradient heating treatment of T1-Tn at a third temperature Tt; and finally, stripping the support body in the treated laminated body to obtain the treated liquid crystal polymer film. Compared with the prior art, the liquid crystal polymer film with good elongation at break, wear resistance and heat resistance can be obtained.

Description

Technical Field

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

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

[0003] In the prior art, the blown film method is generally used to manufacture LCP film. Through transverse blowing and longitudinal stretching, the prepared LCP primary film can achieve a good balance of mechanical properties in the mechanical direction (MD) and the perpendicular mechanical direction (TD). However, the prepared LCP primary film still has problems such as poor surface wear resistance (easy to rub and fluff), obvious micro-layered structure (easy to have skin-core separation affecting the bonding strength with copper foil), low elongation at break, insufficient heat resistance, etc., making it impossible to directly use it as an insulating substrate on devices such as flexible circuit boards (PC). In order to improve the above-mentioned performance defects, the prior art mainly adopts a method of heat treatment of the LCP primary film, such as disclosed in patent CN110760310: heating the LCP primary film to 250°C at a relatively low heating and cooling rate, and then heat-treating for 6 hours, which can improve the brittleness of the LCP film. Another example is disclosed in patent CN1232860: using T m Gradient temperature increase heat treatment starting from a temperature below (critical temperature of a substance from solid to liquid, melting point temperature) can improve the surface wear resistance and heat resistance of the LCP film.

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

[0005] In order to improve the elongation at break of the material, patent US5529740 discloses the use of T m The method of heat treatment at +20℃ or above for 2-10min can improve the elongation at break, wear resistance and eliminate the micro-layered structure of the LCP film, but 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, wear resistance, and heat resistance at the same time is a technical problem that needs to be urgently solved in this application. 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 elongation at break, wear resistance, heat resistance and other characteristics.

[0008] In order to achieve the above object, the present application proposes a method for manufacturing a liquid crystal polymer film, comprising the following steps: The method for manufacturing a liquid crystal polymer film comprises the following steps: (1) thermally compounding a primary film of a liquid crystal polymer with a support to obtain a laminate; (2) The laminate obtained in step (1) is subjected to a temperature increase treatment under the protection of an inert gas and is heated to a first temperature T a After the preset time of heat preservation, the temperature is lowered to the second temperature T b Below. Among them, (T m +10℃)≤T a ≤(T m +60℃), T m is the melting peak temperature of the primary film, T b ≤(T c -10℃), T c The peak crystallization temperature of the primary film during cooling; (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) Peeling off the support in the laminate treated in step (3) to obtain a liquid crystal polymer film.

[0009] Further preferably, T a T may also be preferably m +15℃、T m +20℃、T m +25℃、T m +30℃、T m +40℃, or T m +50℃, etc.

[0010] Further preferably, (T m +15℃)≤T a ≤(T m +50℃).

[0011] Further preferably, T b ≤(T c -20℃).

[0012] Further preferably, T b T c -10℃, T c -11℃, T c -15℃, etc.

[0013] Optionally, the heating rate during the heating process in step S2 is 5-40°C / min; Further preferably, the heating rate during the heating treatment in S2 is 10-30°C / min.

[0014] Further preferably, the preset time is 1 to 20 minutes.

[0015] Further preferably, the T n It is a constant temperature or a variable temperature.

[0016] Further preferably, the preset time period of the gradient temperature increase heat treatment is at least 3 hours.

[0017] Further preferably, the preset time period is 3 to 24 hours; And / or, the time of each stage of heating treatment is 0.5-4h; And / or, said n is 2-10.

[0018] Further preferably, the attachment layer is a metal foil layer; And / or, the thickness of the attachment layer is 30-100 μm; And / or, the surface roughness of the attachment layer is less than 0.3 μm.

[0019] Further preferably, the primary film is composited with the support body in a single-sided composite or double-sided composite manner.

[0020] Further preferably, the metal foil of the attachment layer is any one of copper foil, stainless steel foil and aluminum foil, or a combination thereof.

[0021] Further preferably, the heating method of the heat treatment is any one of infrared lamps, far-infrared radiation heating plates, hot air or heat transfer oil, or a combination thereof.

[0022] Further preferably, the inert gas is nitrogen.

[0023] Further preferably, the oxygen content under the protection of the inert gas is required to be less than 1000 ppm.

[0024] Further preferably, the primary film of the liquid crystal polymer is prepared by a film blowing method.

[0025] Further preferably, before the step of peeling off the support in the stack to obtain the liquid crystal polymer film, the stack is cooled to room temperature.

[0026] The present application also provides a liquid crystal polymer film, which is prepared by the above-mentioned method for manufacturing the liquid crystal polymer film.

[0027] Further preferably, the tensile strength of the liquid crystal polymer film along the horizontal mechanical direction is greater than 169 MPa; And / or, the tensile strength of the liquid crystal polymer film in the vertical mechanical direction is greater than 153 MPa; and / or, the elongation at break of the liquid crystal polymer film along the horizontal mechanical direction is greater than 24%; And / or, the elongation at break of the liquid crystal polymer film along the vertical mechanical direction is greater than 26%; And / or, the thermal deformation temperature of the liquid crystal polymer film is above 269°C.

[0028] Further preferably, the tensile strength of the liquid crystal polymer film along the horizontal mechanical direction is 169MPa~182MPa; Further preferably, the tensile strength of the liquid crystal polymer film along the vertical mechanical direction is 153MPa~158MPa; Further preferably, the elongation at break of the liquid crystal polymer film along the horizontal mechanical direction is 24% to 34%; Further preferably, the elongation at break of the liquid crystal polymer film along the vertical mechanical direction is 26%-32%.

[0029] 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 make the manufactured liquid crystal polymer film have good elongation at break, wear resistance, heat resistance and other characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the heat treatment process of the LCP film in Example 1 of the present application; Figure 2This is the DSC graph of the LCP primary film in Comparative Example 1 of the present application; Figure 3 This is a microscopic morphology of the brittle section of the LCP film in Example 1 of the present application; Figure 4 This is a microscopic morphology of the brittle section of the LCP film in Example 2 of the present application; Figure 5 This is a microscopic morphology of the brittle section of the LCP film in Example 3 of the present application; Figure 6 This is a microscopic morphology of the brittle section of the LCP film in Comparative Example 1 of the present application; Figure 7 T n Schematic diagram of the heat treatment process with variable temperature scheme. DETAILED DESCRIPTION

[0031] The following will be combined with the schematic diagram to describe the manufacturing method of the liquid crystal polymer film of the present application in more detail, wherein the preferred embodiment of the present application is shown, and it should be understood that those skilled in the art can modify the present application described herein, and still achieve the beneficial effects of the present application. Therefore, the following description should be understood as being widely known to those skilled in the art, and not as a limitation to the present application.

[0032] Implementation Method 1 The first embodiment provides a method for manufacturing a liquid crystal polymer film, comprising the following steps: Step S1: thermally compounding a primary film of a liquid crystal polymer with a support to obtain a laminate; Step S2: The laminate obtained in step S1 is subjected to a temperature-raising treatment under the protection of an inert gas and heated to a first temperature T a After the preset time of heat preservation, the temperature is lowered to the second temperature T b Below. Among them, (T m +10℃)≤T a ≤(T m +60℃), T m is the melting peak temperature of the primary film, T b ≤(T c -10℃), T c It is the crystallization peak temperature of the material constituting the primary film during the cooling process.

[0033] In addition, it is worth mentioning that, as a preferred method, T in this embodiment m Preferably 280°C, T c The preferred temperature is 240° C., which is only taken as an example for illustration without further specific limitation or elaboration.

[0034] Step S3: The laminate obtained by the step S2 is heated at a third temperature T under the protection of an inert gas. t Within, perform T1~T n Gradient temperature increase treatment. Among them, 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; Step S4: peeling off the support in the laminate obtained by the treatment in step S3 to obtain a liquid crystal polymer film.

[0035] Through the above steps, it can be known that: the present application performs high-temperature short-time heat treatment, cooling and gradient heating long-time heat treatment on the laminate of the LCP primary film and the support body, and reasonably controls the heating rate and the degree of cooling, so that the liquid crystal polymer film peeled off after the heat treatment has excellent wear resistance, greatly improved elongation at break, excellent heat resistance, and better elimination of the layered microstructure in the film.

[0036] In addition, in the process of heating up and then cooling the laminate, the oxygen content under the protection of the inert gas is controlled to be below 1000 ppm, and the first temperature T a Controlled at (T m +10℃)~(T m +60℃), it can avoid the LCP film's elongation at break not being significantly increased and the layered structure not being eliminated significantly due to too low a temperature, and it can also avoid the LCP film in the laminate being easily degraded or being adhered to the support and difficult to separate due to too high a temperature.

[0037] Optionally, the above T n is a constant temperature, wherein n represents the number of stages, that is, the number of gradient heating stages, and n may preferably be three times, five times, ten times, or more times, etc.

[0038] As another alternative, Figure 7 As shown, the above T n At least part of it is a variable temperature, and no specific limitation or detailed description will be given here.

[0039] Optionally, in the above step S1, the stack is heated to a first temperature T under the protection of an inert gas. a, that is (T m +10℃)≤T a ≤(T m +60℃) range, where T a It may be preferably (T m +15℃)~(T m +50℃).

[0040] Optionally, the primary film of the liquid crystal polymer is prepared by a film blowing method.

[0041] In the above step S2, at the first temperature T a After the preset time of heat preservation, the temperature is lowered to the second temperature T b The following, namely T b ≤(T c -10℃) to obtain the laminated body, T b T c -10℃, T c -11℃, T c -15℃, etc.

[0042] As a further preferred embodiment, the above T b ≤(T c -20℃), for example, T b Preferably T c -20℃, T c -30℃, T c -40℃, etc., so as to ensure that the LCP film in the stack can be fully cooled and crystallized, so that the crystallized area formed in this stage is conducive to the subsequent multi-step gradient temperature rise heat treatment, thereby promoting the growth and improvement of crystals / crystal areas in the gradient temperature rise heat treatment process, thereby improving heat resistance.

[0043] Optionally, in the above step S2, the heating rate during the above heating treatment 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. This heating rate can avoid the obvious thermal history caused by too small a heating rate during the slow heating process, resulting in an insignificant increase in the elongation at break of the LCP film, an insignificant elimination of the micro-layered structure, etc., and avoid the bubbling phenomenon caused by uneven rapid heating of the membrane surface due to too fast a heating rate, thereby obtaining a better heat treatment effect.

[0044] Further optionally, the heating rate during the above-mentioned heating treatment is preferably 10-30°C / min.

[0045] Optionally, in the above step S2, the first temperature T aThe preset time of the lower insulation treatment is 1 to 20 minutes, for example, preferably 5 minutes, 10 minutes, 15 minutes, etc.

[0046] Optionally, in the above step S3, the above stacked body is heated to a third temperature T under the protection of an inert gas. t , and the preset time period for the multi-stage gradient temperature increase heat treatment is at least 3 hours, for example, 3 hours to 24 hours.

[0047] Furthermore, as a preferred method, the time of each stage of the temperature rise treatment is 0.5-4h, such as 0.5h, 1h, 2h, etc. By performing the temperature rise treatment on the laminate in stages, the liquid crystal film layer in the laminate can be better formed and the growth of crystals / crystal regions can be promoted, thereby gradually improving the heat resistance (melting point) of the film, and by extending the heat treatment time of each stage in the gradient temperature rise stage, the heat treatment temperature T of the next step n can be ensured. n Greater than T n-1 , and less than T c -10℃, compared with the single temperature heat treatment method, it is easier to form a crystal zone, and in the process of gradual heating, it promotes the growth and expansion of the crystal zone, so that the heat resistance (melting point) of the film can reach a specific value in a shorter time.

[0048] Optionally, the support body is a metal foil, such as any one of copper foil, stainless steel foil, and aluminum foil, or a combination thereof.

[0049] Optionally, the thickness of the support body is 30-100 μm to meet actual process and production requirements and save costs.

[0050] Optionally, the surface roughness Ra of the support is less than 0.3 μm to avoid excessive surface roughness, which may result in excessive bonding force between the liquid crystal polymer and the support in the laminate after heat treatment and make separation difficult, thereby causing local damage or deformation affecting mechanical properties.

[0051] Optionally, the heating method of the above heat treatment is any one of infrared lamps, far-infrared radiation heating plates, hot air or heat transfer oil, or a combination thereof.

[0052] In this embodiment, there is no particular limitation on the inert gas as long as it does not react with the LCP film. Typically, at least one of nitrogen, helium, and argon is used.

[0053] Optionally, the oxygen content under the protection of the above-mentioned inert gas is required to be less than 1000 ppm to prevent excessively high oxygen content from causing thermal degradation and yellowing of the liquid crystal polymer film.

[0054] The LCP primary films in this embodiment are all made by the blown film method. The blowing ratio in the blown film method is 6.4, the draft 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. Figure 2 shown.

[0055] The following embodiments of the present application are used to explain the present application and should not be construed as limiting the present application.

[0056] Embodiment 1 This embodiment provides a method for manufacturing an LCP film, which comprises the following steps: Step S1: thermally compounding 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; Step S2: placing the single-sided laminate obtained in step S1 in a hot air drying oven under the protection of an inert gas, heating the temperature to 320° C. at a heating rate of 10° C. / min, and keeping the temperature for 5 minutes, and then cooling the temperature to 220° C.; Step S3: heating the single-sided laminate treated in step S2 to 250°C for 3 hours, then to 260°C for 3 hours, then to 270°C for 3 hours, and then to 275°C for 2 hours; Step S4: peeling off the support in the single-sided laminate treated in step S3 to obtain an LCP film.

[0057] Embodiment 2 This embodiment provides a method for manufacturing an LCP film, which comprises the following steps: Step S1: thermally compounding 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; Step S2: placing the single-sided laminate obtained in step S1 in a hot air drying oven under the protection of an inert gas, heating the temperature to 320° C. at a heating rate of 10° C. / min, and keeping the temperature for 5 minutes, and then cooling the temperature to 220° C.; Step S3: heating the single-sided laminate treated in step S2 to 260°C and keeping it for 3 hours, then heating it to 270°C and keeping it for 3 hours, then heating it to 275°C and keeping it for 3 hours, and then heating it to 280°C and keeping it for 2 hours; Step S4: peeling off the support in the single-sided laminate treated in step S3 to obtain an LCP film.

[0058] Embodiment 3 This embodiment provides a method for manufacturing an LCP film, which comprises the following steps: Step S1: thermally compounding 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; Step S2: placing the single-sided laminate obtained in step S1 in a hot air drying oven under the protection of an inert gas, heating the temperature to 300° C. at a heating rate of 10° C. / min, and keeping the temperature for 5 minutes, and then cooling the temperature to 210° C.; Step S3: heating the single-sided laminate treated in step S2 to 250°C for 3 hours, then to 260°C for 3 hours, then to 270°C for 3 hours, and then to 275°C for 2 hours; Step S4: peeling off the support in the single-sided laminate treated in step S3 to obtain an LCP film.

[0059] Embodiment 4 This embodiment provides a method for manufacturing an LCP film, which comprises the following steps: Step S1: thermally compounding the LCP primary 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; Step S2: placing the double-sided laminate treated in step S1 in a hot air drying oven under the protection of an inert gas, heating the laminate to 320° C. at a heating rate of 10° C. / min, keeping the temperature for 5 min, and then cooling the laminate to 220° C.; Step S3: the double-sided laminate treated in step S2 is further heated to 250°C and kept at this temperature for 3 hours, then heated to 260°C and kept at this temperature for 3 hours, then heated to 270°C and kept at this temperature for 3 hours, and then heated to 275°C and kept at this temperature for 2 hours; Step S4: peeling off the support in the double-sided laminate treated in step S3 to obtain an LCP film.

[0060] Comparative Example 1 This comparative example provides an LCP film, which is a primary LCP film, that is, the primary LCP film used in Examples 1 to 3 above.

[0061] Comparative Example 2 This comparative example provides a method for manufacturing an LCP film, which comprises the following steps: Step S1: thermally compounding 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; Step S2: placing the single-sided laminate obtained in step S1 in a hot air drying oven under the protection of an inert gas, heating the temperature to 320° C. at a heating rate of 10° C. / min, and keeping the temperature for 5 minutes, and then cooling to room temperature; Step S3: peeling off the support in the single-sided laminate treated in step S2 to obtain an LCP film.

[0062] Comparative Example 3 This comparative example provides a method for manufacturing an LCP film, which comprises the following steps: Step S1: thermally compounding 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; Step S2: Place the single-sided laminate treated in step S1 in a hot air drying oven under the protection of inert gas, heat it to 250°C at a heating rate of 10°C / min and keep it for 3 hours, heat it to 260°C and keep it for 3 hours, heat it to 270°C and keep it for 3 hours, heat it to 275°C and keep it for 2 hours, and then cool it to room temperature. Step S3: peeling off the support in the single-sided laminate treated in step S2 to obtain an LCP film.

[0063] Comparative Example 4 This comparative example provides a method for manufacturing an LCP film, which comprises the following steps: Step S1: thermally compounding 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; Step S2: placing the single-sided laminate treated in step S1 in a hot air drying oven under the protection of an inert gas, heating it to 320° C. at a heating rate of 10° C. / min, keeping the temperature for 5 minutes, and then cooling it to 260° C.; Step S3: keeping the single-sided laminate treated in step S2 at 260° C. for 3 h, heating it to 270° C. for 3 h, heating it to 275° C. for 3 h, and then heating it to 280° C. for 2 h; Step S4: peeling off the support in the single-sided laminate treated in step S3 to obtain an LCP film.

[0064] Implementation Method 2 The second embodiment provides a liquid crystal polymer film, which is prepared by the method for manufacturing a liquid crystal polymer film provided in the first embodiment.

[0065] The present invention conducted the following performance tests on the above embodiments and comparative examples.

[0066] The testing methods for the embodiments and comparative examples are as follows: 1. Mechanical properties test: According to ASTM D882, the test instrument is INSTRON 5965 electronic universal tensile testing machine. The size of the cut sample is 100mm × 10mm, the distance between the clamps is 50mm, the tensile rate is 25mm / min, and the tensile strength and elongation at break are tested and recorded.

[0067] 2. Melting point test: According to GB / T19466.3-2004, the test instrument is DSC250 differential scanning calorimeter. Under nitrogen protection, the sample is heated from 25℃ to 330℃ at a rate of 10℃ / min, and the peak value of the melting peak is recorded as the melting point T m The temperature at the starting position of the melting peak is recorded as the starting melting temperature T o .

[0068] 3. Heat deformation temperature test: According to GB / T1634.2-2019, the test instrument is TMA450 thermomechanical analyzer. A load of 1g is applied to the test sample with a width of 5mm and a length of 20mm, and then the temperature is raised to 310℃ at a heating rate of 10℃ / min to obtain the temperature-dimensional change rate curve. The intersection of the tangent lines of the curve before and after the sudden change in the dimensional change rate is called the heat deformation temperature.

[0069] 4. Scanning electron microscope (SEM) test: The test instrument is an EVOMA10 scanning electron microscope. The LCP film is brittlely fractured along the vertical mechanical direction (TD) under liquid nitrogen conditions, and the brittle fracture surface is obtained under high vacuum conditions with a voltage of 4.0 kV. The surface microscopic layered structure is observed after gold spraying.

[0070] 5. Wear resistance test: Place a square block with a bottom of 10mm×15mm covered with fabric cloth on the surface of the liquid crystal polymer film, load a 500g weight on the block, and then move back and forth 30mm on the surface of the LCP film. After 1h of continuous movement, observe the changes in the surface of the LCP film. The situation where a large number of fibrils are generated is evaluated as poor wear resistance, the situation where no fibrils are generated is evaluated as excellent wear resistance, and the situation in between is evaluated as medium wear resistance.

[0071] The test results of the embodiments and comparative examples are as follows: Table 1 Performance test results of LCP films prepared in the embodiments and comparative examples

[0072] Table 2 Comparison of LCP films in the heat treatment stage in the examples and comparative examples Figure 1

[0073] Table 3 Comparison of LCP films in the heat treatment stage in the examples and comparative examples Figure 2

[0074] According to the test results of the LCP films corresponding to Examples 1-4 and Comparative Examples 1-4 statistically shown in Tables 1 to 3, the tensile strength of the LCP film prepared by the method provided in the present application can reach more than 169 MPa in the horizontal mechanical direction (MD), and the tensile strength can reach more than 153 MPa in the vertical mechanical direction (TD); the elongation at break in the horizontal mechanical direction (MD) can reach more than 24.4%, and the elongation at break in the vertical mechanical direction (TD) can reach more than 26.5%; the heat deformation temperature of the LCP film is more than 269°C.

[0075] In addition, it can be seen from Comparative Example 4 and Table 1 that there are two melting point peaks in the DSC test results of the LCP film prepared in Comparative Example 4, which is caused by inappropriate selection of cooling temperature. In other words, the prepared finished film has defects such as poor heat resistance and stability.

[0076] In addition, from the attached Figures 3 to 6 It can also be seen from the brittle cross-section morphology images of the LCP films provided in the examples and comparative examples that the LCP film prepared by the method provided in the present application can better eliminate the microscopic layered structure in the film, thereby better improving its elongation at break.

[0077] It can be seen that the LCP film prepared by the above steps has the advantages of excellent elongation at break, heat resistance and wear resistance.

[0078] The above are only preferred embodiments of the present application and do not have any limiting effect on the present application. Any technical personnel in the relevant technical field, without departing from the scope of the technical solution of the present application, may make any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present application, which shall be deemed as the content of the technical solution of the present application and still fall within the protection scope of the present application.

Claims

1. A method for producing a liquid crystal polymer film, characterized in that: The following steps are involved: (1) thermally compounding a primary film of a liquid crystal polymer with a support to obtain a laminate; (2) The laminate obtained in step (1) is subjected to a temperature-raising treatment under the protection of an inert gas and heated to a first temperature T a After the preset time of heat preservation, the temperature is lowered to the second temperature T b The following, where (T m +10℃)≤T a ≤(T m +60℃), T m is the melting peak temperature of the primary film, T b ≤(T c -10℃), T c The peak crystallization temperature of the primary film during cooling; (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) Peeling off the support in the laminate treated in step (3) to obtain a liquid crystal polymer film.

2. The method for producing a liquid crystal polymer film according to claim 1, characterized in that: The primary film of the liquid crystal polymer is prepared by a film blowing method.

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

4. The method for producing a liquid crystal polymer film according to claim 1, characterized in that: In step (1), the primary film and the support are composited in a single-sided composite or double-sided composite manner.

5. The method for producing a liquid crystal polymer film according to claim 1, characterized in that: In step (2), the first temperature T a The preset time for the lower insulation treatment is 1~20min.

6. The method for producing a liquid crystal polymer film according to claim 1, characterized in that: In step (2), the heating rate during the heating process is 5-40°C / min.

7. The method for producing a liquid crystal polymer film according to claim 1, characterized in that: In step (3), the preset time period of the gradient temperature increase treatment is 3 to 24 hours; The time of heating treatment in each stage is 0.5-4h; And / or, said n is 2 to 10; And / or, the heating rate during the heating treatment is 10-30°C / min.

8. The method for producing a liquid crystal polymer film according to claim 1, characterized in that: The heating method of the heat treatment is any one of infrared lamps, far-infrared radiation heating plates, hot air or heat transfer oil, or a combination thereof.

9. The method for producing a liquid crystal polymer film according to claim 1, characterized in that: During the heating and heat preservation process, the oxygen content under the protection of inert gas is required to be less than 1000 ppm.

10. A liquid crystal polymer film, characterized in that: The method for producing a liquid crystal polymer film is used to prepare the liquid crystal polymer film.

11. The liquid crystal polymer film according to claim 10, characterized in that: The tensile strength of the liquid crystal polymer film along the horizontal mechanical direction is above 169 MPa; And / or, the tensile strength of the liquid crystal polymer film in the vertical mechanical direction is greater than 153 MPa; and / or, the elongation at break of the liquid crystal polymer film along the horizontal mechanical direction is greater than 24%; And / or, the elongation at break of the liquid crystal polymer film along the vertical mechanical direction is greater than 26%; And / or, the thermal deformation temperature of the liquid crystal polymer film is above 269°C.

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