Biaxially-oriented ultrathin PEEK film and preparation method thereof
By introducing self-crosslinking polyetherimide and modified nanocrystals into PEEK membranes, combined with a step-temperature controlled biaxial stretching process, the problem of unstable mechanical properties in the production of ultrathin PEEK membranes was solved, achieving high strength and uniformity, and ensuring production stability and quality.
Patent Information
- Application Number
- CN202512031452.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-03-06
AI Technical Summary
Existing biaxial stretching processes are difficult to achieve stable and efficient production while ensuring the mechanical properties of ultrathin PEEK films. In particular, the films are prone to excessive softening or increased brittleness when the temperature changes, resulting in uneven stretching and edge breakage.
Polyetheretherketone (PEEK) is modified by using self-crosslinking polyetherimide containing self-crosslinking functional groups and modified nanocrystals. By forming a network crosslinking structure and acting as a nucleating agent, the relationship between toughness and strength is balanced, and the crystallization performance and crystallization rate are adjusted. This is combined with a biaxial stretching process with step-temperature control.
It improves the processing and mechanical properties of ultra-thin PEEK film, ensures production stability, avoids film breakage and uneven thickness, and achieves high strength and uniform biaxial stretching effect.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer films, and in particular to a biaxially stretched ultrathin PEEK film and its preparation method. Background Technology
[0002] PEEK sheet film is a high-performance special engineering plastic film made of polyetheretherketone (PEEK). It has excellent properties such as high temperature resistance, chemical corrosion resistance, flame retardancy, wear resistance, and dimensional stability, and is widely used in many fields such as electronics, aerospace, automobiles, and medical.
[0003] Currently, the preparation of PEEK films mainly relies on two processes: casting and biaxial stretching. Casting typically involves extrusion through a T-die followed by rapid cooling and shaping. The resulting film is usually unstretched and non-oriented. While it can produce ultrathin PEEK films with a thickness of only 6 μm, the non-oriented structure of ultrathin PEEK leads to relatively insufficient mechanical strength, resulting in problems such as film breakage and limited width during production or use, directly affecting the production stability and application range of PEEK films. On the other hand, biaxial stretching further stretches the film or sheet longitudinally and laterally to form even thinner films. While biaxial stretching not only offers high production stability and reduces the risk of film breakage, it also significantly improves the orientation and crystallinity of the film through high-temperature stretching, achieving improved mechanical strength and wider film width.
[0004] However, due to the inherent properties of PEEK, existing biaxial stretching processes still face numerous challenges in preparing ultrathin PEEK films, making it difficult to achieve stable and efficient production while ensuring the film's mechanical properties. Since the mechanical modulus of PEEK changes significantly with temperature above its softening point, the temperature range suitable for stretching the film is relatively narrow. At slightly higher temperatures, the film softens excessively, easily leading to necking and uneven thickness during stretching. Conversely, at slightly lower temperatures, the film's brittleness increases significantly due to improved orientation, easily resulting in stress concentration points during stretching. This not only leads to stress imbalance and uneven tensile force distribution but also amplifies the edge effect, making edge clamping points more prone to tensile fracture. These problems become even more pronounced as the target film thickness decreases, severely restricting the preparation and application of ultrathin PEEK films. Therefore, developing a preparation method that can guarantee excellent mechanical properties of ultrathin PEEK films while achieving stable and efficient production has become an urgent technical challenge. Summary of the Invention
[0005] To improve the mechanical properties of ultrathin PEEK films, balance the relationship between the toughness and strength of the films, and enhance the production stability of ultrathin PEEK films to ensure that they are not easily broken during production, this application provides a biaxially oriented ultrathin PEEK film and its preparation method.
[0006] Firstly, the ultrathin PEEK film provided in this application adopts the following technical solution: An ultrathin PEEK film, produced by extrusion followed by biaxial stretching, comprises the following raw materials in parts by weight: Polyetheretherketone: 100 parts; Self-crosslinking polyetherimide: 5-20 parts; Modified nanocrystals: 0.05-1 part; The self-crosslinking polyetherimide is a polyetherimide synthesized from dianhydride monomer, diamine monomer and self-crosslinking functional monomer. The self-crosslinking functional monomer is one of 4-phenylethynyl phthalic anhydride, or a combination of 4-phenylethynyl phthalic anhydride and 4-aminobenzocyclobutene. The modified nanocrystals are obtained by surface modification treatment of nano-inorganic whiskers with a coupling agent.
[0007] By adopting the above technical solution, polyetheretherketone (PEEK) is modified by using self-crosslinking polyetherimide containing self-crosslinking functional groups and modified nanocrystals. The self-crosslinking groups in the self-crosslinking polyetherimide can form a moderate network crosslinking structure during the melt extrusion of PEEK. Combined with the nucleating effect of the modified nanocrystals, the resulting synergistic effect can effectively improve the processing performance of PEEK and balance the relationship between toughness and strength during the orientation crystallization of PEEK. It can also regulate the crystallization performance and crystallization rate of PEEK to a certain extent, thereby improving the stability during biaxial stretching. At the same time, it can effectively prevent problems such as film breakage and tearing during biaxial stretching. It has successfully achieved the preparation of ultrathin PEEK films with high strength using the biaxial stretching method.
[0008] Optionally, the method for preparing the self-crosslinking polyetherimide includes the following steps: A1. Dissolve the dianhydride monomer completely in an anhydrous solvent to obtain an anhydride solution; dissolve the diamine monomer completely in an anhydrous solvent to obtain a diamine solution; dissolve the self-crosslinking functional monomer completely in an anhydrous solvent to obtain a capping agent; A2. At room temperature, add equal amounts of the diamine solution to the anhydride solution in multiple portions. After each addition, stir until the solution is clear before adding more. After each addition, continue stirring at room temperature for at least 12 hours. After the reaction is complete, add the end-capping agent and continue the reaction at room temperature for at least 6 hours to obtain a precursor solution. Add an imidization catalyst to the precursor solution, heat to 40-60°C and keep the temperature for 1-3 hours to obtain a self-crosslinking polyetherimide solution. A3. Pre-cool the ethanol-water solution to below 5°C to obtain a precipitate base solution. Then, under continuous stirring, add the self-crosslinking polyetherimide solution dropwise to the precipitate base solution. After the addition is complete, stir evenly and let stand. Separate and collect the precipitate by high-speed centrifugation. After thoroughly washing the precipitate, vacuum dry, pulverize and sieve to obtain the self-crosslinking polyetherimide.
[0009] Optionally, the molar ratio of the dianhydride monomer, the diamine monomer, and the capping agent is 1:(1.1-1.2):(0.15-0.25). Wherein, the dianhydride monomer is bisphenol A type diether dianhydride; the diamine monomer is a combination of 4,4'-diaminodiphenyl ether and 1,4-phenylenediamine, and the molar ratio of 4,4'-diaminodiphenyl ether and 1,4-phenylenediamine is 1:(1.5-4).
[0010] By adopting the above technical solution, bisphenol A type diether dianhydride can impart good flexibility to self-crosslinking polyetherimide, while the synergistic combination of 4,4'-diaminodiphenyl ether and 1,4-phenylenediamine can balance the rigidity and heat resistance of self-crosslinking polyetherimide. After being combined with a capping agent in a specific molar ratio, it can be ensured that the self-crosslinking polyetherimide forms a moderate crosslinking network in the polyether ether ketone matrix. This helps to prevent the problems of excessive rigidity of polyether ether ketone and easy breakage of film due to excessive crosslinking, or insufficient crosslinking that cannot effectively improve processing performance. It is also beneficial to further optimize the stability of the biaxial stretching process and the mechanical properties of the final film.
[0011] Optionally, the self-crosslinking functional monomer is specifically a composition of 4-phenylethynyl phthalic anhydride and 4-aminobenzocyclobutene; When preparing the end-capping agent in A1, the molar ratio of the 4-phenylethynyl phthalic anhydride and the 4-aminobenzocyclobutene is (1.05-1.1):1. After the 4-phenylethynyl phthalic anhydride and the 4-aminobenzocyclobutene are dissolved in an anhydrous solvent, they need to be heated to 40-60℃ and stirred for 3-4 hours. After cooling, the end-capping agent is obtained.
[0012] By adopting the above technical solution, it is possible to attach two active groups, phenylacetylene and benzocyclobutenyl, to polyetherimide without affecting each other. Furthermore, since the self-crosslinking temperature of benzocyclobutenyl is 200-280℃, it can stably undergo self-crosslinking in the high-temperature environment of polyetheretherketone melt extrusion. Therefore, when the self-crosslinked polyetherimide contains both phenylacetylene and benzocyclobutenyl active groups, their content in the self-crosslinked polyetherimide can be precisely and stably adjusted to regulate the crosslinking network density of the self-crosslinked polyetherimide in the polyetheretherketone matrix. This is beneficial for improving the melt strength and toughness of polyetheretherketone, and for dispersing internal stress concentration points during calendering and further biaxial stretching, achieving more uniform and stable biaxial stretching, which is conducive to further improving the processing performance and mechanical properties of ultrathin PEEK films.
[0013] Optionally, the imidization catalyst is a composition of triethylamine and acetic anhydride, wherein the molar ratio of triethylamine to acetic anhydride is 1:(1-1.5), and the amount of imidization catalyst added is 10-12% of the total molar amount of the dianhydride monomer and the diamine monomer.
[0014] By adopting the above technical solution, compared with a single catalyst, the combination of triethylamine and acetic anhydride can effectively shorten the imidization reaction time, while also helping to prevent polymer molecular chain degradation caused by over-catalysis, thus ensuring the performance stability of the obtained cross-linked polyether imide.
[0015] Optionally, the nano-inorganic whiskers are at least one of zinc oxide whiskers, aluminum borate whiskers, potassium titanate whiskers, or silicon carbide whiskers; the coupling agent is an aluminum-titanium composite coupling agent.
[0016] By adopting the above technical solution, the aluminum-titanium composite coupling agent can form a chemically bonded layer on the surface of nanowhiskers, effectively solving the problem of easy agglomeration of nanowhiskers in polyetheretherketone (PEEK), enabling them to be uniformly dispersed and ensuring their modification effect. The dispersed nanowhiskers can then act as nucleating agents and regulate the crystallization properties and rate of PEEK. This not only compensates for the decrease in crystallization rate caused by the addition of self-crosslinking polyetherimide, ensuring uniform orientation and crystallization of PEEK during biaxial stretching, but also further enhances the mechanical properties of ultrathin PEEK films by adjusting the crystallinity in conjunction with the self-crosslinking polyetherimide to balance the toughness and strength of the film.
[0017] Optionally, the nanocrystals are a combination of aluminum borate whiskers and potassium titanate whiskers, and the mass ratio of the aluminum borate whiskers to the potassium titanate whiskers is 1:(1-2).
[0018] By adopting the above technical solution, the synergistic effect of aluminum borate whiskers and potassium titanate whiskers in promoting crystallization can be achieved. When the two are used in combination at a mass ratio of 1:(1-2), the nucleation efficiency and crystallization uniformity of polyetheretherketone can be adapted to the biaxial stretching process of this application. This not only effectively ensures the mechanical properties and thickness uniformity of the ultrathin PEEK film during stretching, but also the modified nano-whiskers obtained can approach the modification effect of modified silicon carbide whiskers in terms of overall modification effect. Since aluminum borate whiskers and potassium titanate whiskers are more common reinforcing materials in industry, their cost is much lower than that of silicon carbide whiskers, which is conducive to controlling the large-scale production cost of ultrathin PEEK films.
[0019] Secondly, the method for preparing an ultrathin PEEK film provided in this application adopts the following technical solution: A method for preparing a PEEK membrane includes the following steps: S1. By mass, the polyether ether ketone, self-crosslinking polyether imide and modified nanocrystal whiskers are thoroughly mixed, and then the mixed powder is melt-extruded through an extruder. After the melt flows out, it is calendered using a three-roll calender to obtain a primary film. S2. The primary film obtained in S1 is introduced into an oven, and then preheated, stretched longitudinally, stretched laterally and heat-set in the oven in sequence. Then it is cooled, trimmed, and wound up to obtain the ultra-thin PEEK film.
[0020] Optionally, in S1, the extruder adopts four-zone heating, with the first zone heating temperature set to 335-340℃, the second zone heating temperature set to 345-360℃, the third zone heating temperature set to 375-380℃, the fourth zone heating temperature set to 375-385℃, and the extrusion die temperature set to 380-385℃. The three-roll calender includes an inlet roll, a main pressure roll, and an outlet roll, wherein the temperature of the inlet roll is set to 110-120℃, the temperature of the main pressure roll is set to 100-110℃, and the temperature of the outlet roll is set to 90-105℃.
[0021] By adopting the above technical solution, the higher extrusion temperature helps ensure that the high-melting-point polyetheretherketone (PEEK) is fully melted and mixed with the self-crosslinking polyetherimide and modified nanocrystals. Simultaneously, it can initiate a partial self-crosslinking reaction of the self-crosslinking polyetherimide, forming a uniform network crosslinked structure within the PEEK, which facilitates subsequent calendering and biaxial stretching processes. Furthermore, the stepped cooling calendering temperature allows for gradual cooling and shaping of the PEEK melt, preventing internal stress from excessively rapid cooling of the primary film. This improves the thickness uniformity and surface smoothness of the primary film and lays a good foundation for the subsequent biaxial stretching process.
[0022] Optionally, in S2, the oven temperature is set to 140-180℃ during preheating, 165-175℃ during longitudinal stretching, and 175-185℃ during transverse stretching.
[0023] By adopting the above technical solution, the preheating process can bring the primary film to a suitable stretching temperature, preventing the film from becoming brittle due to low temperature in the subsequent process. The temperature gradient design during longitudinal and transverse stretching can guide the molecular chains to achieve ordered orientation, which is beneficial to improving the mechanical strength of the film. At the same time, it can promote the uniform crystallization of polyether ether ketone and, in conjunction with the self-crosslinking reaction of self-crosslinking polyetherimide in the subsequent heat setting process, is beneficial to further improve the tensile strength of the film, thereby realizing the preparation of ultrathin, uniform, and high-strength PEEK film.
[0024] In summary, the technical solution of this application has at least one of the following beneficial effects: 1. By modifying polyether ether ketone with self-crosslinking polyetherimide containing self-crosslinking functional groups and modified nanocrystals, the resulting synergistic effect can effectively improve the processing performance of polyether ether ketone and balance the relationship between toughness and strength during oriented crystallization. It can also regulate the crystallization performance and crystallization rate of polyether ether ketone to a certain extent, which is beneficial to improving the stability during biaxial stretching.
[0025] 2. By introducing phenylacetylene groups and an appropriate amount of benzocyclobutene groups as active groups of self-crosslinking polyetherimide, it is possible to precisely and stably regulate the crosslinking network density formed by self-crosslinking polyetherimide in different process stages. This is beneficial to improving the melt strength and toughness of polyether ether ketone, and to achieving uniform dispersion of internal stress concentration points in calendering and biaxial stretching. This is beneficial to improving the stability and uniformity of biaxial stretching process, and further improving the processing performance and mechanical properties of ultrathin PEEK films.
[0026] 3. When aluminum borate whiskers and potassium titanate whiskers are used in combination at a mass ratio of 1:(1-2), the resulting modified nano-whiskers can make the nucleation efficiency and crystallization uniformity of polyether ether ketone (PEEK) compatible with the biaxial stretching process of this application. This not only effectively ensures the mechanical properties and thickness uniformity of the ultrathin PEEK film during stretching, but also the modified nano-whiskers can approach the modification effect of modified silicon carbide whiskers in terms of overall modification effect, which is beneficial to controlling the large-scale production cost of ultrathin PEEK films. Detailed Implementation
[0027] The present application will be further described in detail below with reference to preparation examples, embodiments and comparative examples.
[0028] The nano-inorganic whiskers were all purchased from Hubei Xinyuhong Biotechnology. Among them, the diameter of the tetraneedle-shaped zinc oxide whiskers is 0.5-0.8μm and the length is 10-20μm; the diameter of the aluminum borate whiskers is 0.5-1μm and the length is 10-20μm; the diameter of the potassium titanate whiskers is 0.5-0.7μm and the length is 10-20μm; and the diameter of the silicon carbide whiskers is 0.1-0.5μm and the length is 5-20μm.
[0029] The aluminum-titanium composite coupling agent was specifically purchased from Hangzhou Jessica Chemical Co., Ltd., with the specific brand name HY-133.
[0030] The polyetheretherketone (PEEK) was specifically purchased from Jida Special Plastics, with the brand name PEEK 021G. Preparation Example
[0031]
Preparation Example 1-1
[0032] A2. At room temperature, add 20% by volume of diamine solution to the acid anhydride solution in 5 portions, stirring until clear after each addition before adding more. After the addition is complete, continue stirring at room temperature for 12 hours. After the reaction is complete, add the end-capping agent and continue the reaction at room temperature for 6 hours to obtain the precursor solution. Add the imidization catalyst to the precursor solution, heat to 60°C and keep it at that temperature for 1 hour to obtain the self-crosslinking polyetherimide solution. In this preparation example, the imidization catalyst is a combination of triethylamine and acetic anhydride, with a molar ratio of 1:1 between triethylamine and acetic anhydride, and the amount of imidization catalyst added is 10% of the total molar amount of dianhydride monomer and diamine monomer.
[0033] A3. Pre-cool a 75wt% ethanol aqueous solution to 5°C to obtain a precipitate. Then, while continuously stirring, add the self-crosslinking polyetherimide solution dropwise to the excess precipitate. After the addition is complete, continue stirring for 10 minutes, let stand for 20 minutes, and then separate and collect the precipitate by high-speed centrifugation. Wash the precipitate three times with anhydrous ethanol, vacuum dry, grind and pulverize it, and pass it through a 500-mesh sieve to obtain the self-crosslinking polyetherimide.
[0034]
Preparation Examples 1-2
[0035] A2. At room temperature, add 20% by volume of diamine solution to the acid anhydride solution in 5 portions, stirring until clear after each addition before adding more. After the addition is complete, continue stirring at room temperature for 12 hours. After the reaction is complete, add the end-capping agent and continue the reaction at room temperature for 8 hours to obtain the precursor solution. Add the imidization catalyst to the precursor solution, heat to 40°C and keep it at that temperature for 3 hours to obtain the self-crosslinking polyetherimide solution. In this preparation example, the imidization catalyst is a combination of triethylamine and acetic anhydride, the molar ratio of triethylamine to acetic anhydride is 1:1.5, and the amount of imidization catalyst added is 12% of the total molar amount of dianhydride monomer and diamine monomer.
[0036] A3. Pre-cool a 75wt% ethanol aqueous solution to 5°C to obtain a precipitate. Then, while continuously stirring, add the self-crosslinking polyetherimide solution dropwise to the excess precipitate. After the addition is complete, continue stirring for 10 minutes, let stand for 20 minutes, and then separate and collect the precipitate by high-speed centrifugation. Wash the precipitate three times with anhydrous ethanol, vacuum dry, grind and pulverize it, and pass it through a 500-mesh sieve to obtain the self-crosslinking polyetherimide.
[0037]
Preparation Examples 1-3
[0038] In this preparation example, the self-crosslinking functional monomer is a composition of 4-phenylethynyl phthalic anhydride and 4-aminobenzocyclobutene, and the mixing molar ratio of 4-phenylethynyl phthalic anhydride and 4-aminobenzocyclobutene is 1.05:1.
[0039] In this preparation example, the method for preparing the capping agent includes the following steps: 4-Phenylacetylphthalic anhydride and 4-aminobenzocyclobutene were mixed and then fully dissolved in N,N-dimethylacetamide. The mixture was heated to 40°C and stirred for 4 hours. After cooling, the end-capping agent was obtained.
[0040]
Preparation Examples 1-4
[0041] In this preparation example, the self-crosslinking functional monomer is 4-aminobenzocyclobutene.
[0042]
Preparation Example 2-1
[0043] A method for preparing modified nanocrystals includes the following steps: First, the coupling agent was prepared into a 5wt% modifier using anhydrous ethanol, the pH was adjusted to 4.5-5, and the mixture was stirred continuously for 10 min. Then, 2 kg of nano-inorganic whiskers were prepared into a whisker dispersion with a solid content of 1wt% using deionized water. After thorough stirring and dispersion, the mixture was heated to 60℃, and the modifier was added dropwise to the whisker dispersion at a rate of 10 ml / min. The mixture was stirred at a constant temperature for 1 h. After the reaction, the precipitate was separated and collected by high-speed centrifugation. The precipitate was washed three times with anhydrous ethanol, then vacuum dried and ground through a 1000-mesh sieve to obtain the modified nano-whiskers.
[0044]
Preparation Example 2-2
[0045] In this preparation example, the nano-inorganic whiskers are specifically aluminum borate whiskers.
[0046]
Preparation Examples 2-3
[0047] In this preparation example, the nano-inorganic whiskers are specifically potassium titanate whiskers.
[0048]
Preparation Examples 2-4
[0049] In this preparation example, the nano-inorganic whiskers are specifically silicon carbide whiskers.
[0050]
Preparation Examples 2-5
[0051] In this preparation example, the nano-inorganic whiskers are specifically a combination of aluminum borate whiskers and potassium titanate whiskers, wherein the mass ratio of aluminum borate whiskers to potassium titanate whiskers is 1:1.
[0052]
Preparation Examples 2-6
[0053] In this preparation example, the nano-inorganic whiskers are specifically a combination of aluminum borate whiskers and potassium titanate whiskers, wherein the mass ratio of aluminum borate whiskers to potassium titanate whiskers is 1:2. Example
[0054]
Example 1
[0055] In this embodiment, the self-crosslinked polyetherimide was prepared according to [Preparation Example 1-1], and the modified nanocrystals were prepared according to [Preparation Example 2-1].
[0056] A method for preparing an ultrathin PEEK film includes the following steps: S1. By mass, polyetheretherketone, self-crosslinking polyetherimide and modified nanocrystals are thoroughly mixed, and then the mixture is melt-extruded through an extruder. After the melt flows out, it is calendered using a three-roll calender to obtain a primary film with a thickness of 50 μm. In this embodiment, the extruder temperature is set in four stages: the first stage temperature is set to 350°C; the second stage temperature is set to 365°C; the third stage temperature is set to 375°C; the fourth stage temperature is set to 385°C; and the die head temperature is set to 385°C. Additionally, the three-roll calender includes an inlet roll, a main pressure roll, and an outlet roll. The inlet roll temperature is set to 120°C, the main pressure roll temperature is set to 110°C, and the outlet roll temperature is set to 105°C.
[0057] S2. The primary film obtained in S1 is introduced into an oven, and then preheated, stretched longitudinally, stretched laterally and heat-set in the oven in sequence. Then it is cooled, trimmed, and wound up to obtain an ultrathin PEEK film with a thickness of 6μm. In this embodiment, the oven temperature is 160°C during preheating, 165°C during longitudinal stretching, 175°C during transverse stretching, and 280°C during heat setting, with a heat setting time of 30 seconds.
[0058]
Example 2
[0059] In this embodiment, the self-crosslinked polyetherimide was prepared according to [Preparation Example 1-2], and the modified nanocrystals were prepared according to [Preparation Example 2-1].
[0060] A method for preparing an ultrathin PEEK film includes the following steps: S1. By mass, polyetheretherketone, self-crosslinking polyetherimide and modified nanocrystals are thoroughly mixed, and then the mixture is melt-extruded through an extruder. After the melt flows out, it is calendered using a three-roll calender to obtain a primary film. In this embodiment, the extruder temperature is set in four stages: the first stage temperature is set to 340°C; the second stage temperature is set to 360°C; the third stage temperature is set to 370°C; the fourth stage temperature is set to 375°C; and the die head temperature is set to 380°C. Additionally, the three-roll calender includes an inlet roll, a main pressure roll, and an outlet roll. The inlet roll temperature is set to 110°C, the main pressure roll temperature is set to 100°C, and the outlet roll temperature is set to 90°C.
[0061] S2. The primary film obtained in S1 is introduced into an oven, and then preheated, stretched longitudinally, stretched laterally and heat-set in the oven in sequence. Then it is cooled, trimmed, and wound up to obtain an ultra-thin PEEK film. In this embodiment, the oven temperature is 160°C during preheating, 175°C during longitudinal stretching, 185°C during transverse stretching, and 280°C during heat setting, with a heat setting time of 30 seconds.
[0062]
Example 3
[0063] In this embodiment, the self-crosslinking polyetherimide was prepared according to [Preparation Examples 1-3].
[0064]
Example 4
[0065] In this embodiment, the modified nanocrystals were prepared according to [Preparation Example 2-2].
[0066]
Example 5
[0067] In this embodiment, the modified nanocrystals were prepared according to [Preparation Examples 2-3].
[0068]
Example 6
[0069] In this embodiment, the modified nanocrystals were prepared according to [Preparation Examples 2-4].
[0070]
Example 7
[0071] In this embodiment, the modified nanocrystals were prepared according to [Preparation Examples 2-5].
[0072]
Example 8
[0073] In this embodiment, the modified nanocrystals were prepared according to [Preparation Examples 2-6]. Comparative Example
[0074] Comparative Example 1 A PEEK membrane, which differs from [Example 1] in that it does not contain self-crosslinking polyetherimide and modified nanocrystals.
[0075] Comparative Example 2 A PEEK film, which differs from [Example 1] in that it does not contain modified nanocrystals.
[0076] Comparative Example 3 A PEEK membrane, which differs from [Example 1] in that it does not contain self-crosslinking polyetherimide.
[0077] Comparative Example 4 A PEEK film, which differs from [Example 1] in that it uses a different self-crosslinking polyetherimide.
[0078] In this comparative example, the self-crosslinking polyetherimide was prepared according to [Preparation Examples 1-4]. Performance test data
[0079] Sample preparation: The samples were prepared according to the process flow of each embodiment and comparative example. The longitudinal and transverse stretching ratios were adjusted to obtain the corresponding sample thicknesses of 6 μm and 25 μm.
[0080] 1. Processing Performance: Observe the film preparation of each sample with a thickness of 6μm and 25μm. Record whether there is large-area damage, tearing or film breakage during the preparation and stretching process. If there is large-area damage, tearing or film breakage, record "film breakage, unqualified" and do not perform corresponding tests in the future. If there is no obvious damage, tearing or film breakage, observe and record whether there are pinholes on the surface of the film after the film has completely cooled and been wound up. If pinholes appear in a randomly selected 1m×1m test area, the pinhole diameter is ≤0.1mm and the number of pinholes is <5, record "a small number of pinholes". If the pinhole diameter is >0.1mm or the number of pinholes is ≥5, record "pinholes, unqualified" and do not perform corresponding tests in the future. If there are no obvious pinholes, record "no obvious defects".
[0081] 2. Thickness Uniformity: Samples measuring 0.5m × 0.5m without obvious damage or perforation were selected from the 6μm and 25μm thickness samples. Thickness was measured at 10 evenly spaced locations with an accuracy of 0.1μm. The average absolute deviation between the thickness at each measurement location and the set thickness was calculated and recorded. Specifically, the average absolute deviation was calculated as follows:
[0082] Among them, d1, d 10 d represents the measured thickness (μm) at different locations. m Set the thickness (μm) for the PEEK film, retaining one decimal place.
[0083] 3. Mechanical properties: Take a 6μm thick sample and test it according to ASTM D882. Record the tensile strength (MPa) of each 6μm thick sample.
[0084] Table 1. Partial test performance data of PEEK membrane.
[0085] Based on Examples 1 and Comparative Examples 1-3, and the data in Table 1, it can be seen that by modifying polyetheretherketone (PEEK) with self-crosslinking polyetherimide containing self-crosslinking functional groups and modified nanocrystals, the processing performance of PEEK can be effectively improved, and the relationship between toughness and strength of PEEK during oriented crystallization can be balanced. This is beneficial to improving the stability of PEEK when using biaxial stretching to prepare films, ensuring that it is not easy to break during stretching, and high-strength, ultra-thin PEEK films can be prepared by biaxial stretching.
[0086] Comparative Examples 2 and 3, along with their data, show that self-crosslinking polyetherimide improves the relationship between toughness and strength of polyetheretherketone (PEEK) during biaxial stretching, preventing tearing and film breakage during the stretching process and thus enhancing the stability of the biaxial stretching. Modified nanofibers act as nucleating agents, regulating the crystallization properties and rate of PEEK to some extent. This not only compensates for the decrease in PEEK crystallization rate caused by the addition of self-crosslinking polyetherimide, ensuring uniform orientation and crystallization of PEEK during biaxial stretching, and synergistically balancing the toughness and strength of PEEK with self-crosslinking polyetherimide, but also further improves the crystallinity of PEEK, thereby enhancing the mechanical properties of the resulting ultrathin PEEK film.
[0087] Based on Examples 1, 3, and Comparative Example 4, and the data in Table 1, it can be seen that when the self-crosslinking active groups in the self-crosslinking polyetherimide are phenylacetylene groups, or phenylacetylene groups and benzocyclobutene groups, polyether ether ketone can be stably stretched without breaking during biaxial stretching. This also helps to improve the mechanical strength of the ultrathin PEEK film. This may be because during the melt extrusion of polyether ether ketone, the high temperature environment can cause the self-crosslinking active groups in the self-crosslinking polyetherimide to undergo partial self-crosslinking. Although the degree of crosslinking is not high, a network crosslinking structure can still be formed in polyether ether ketone, which is beneficial to improving the melt strength and overall toughness of polyether ether ketone. Although the required tensile force is greater during biaxial stretching, the overall stress concentration points can be dispersed and the tensile stability can be improved through the network crosslinking structure, achieving uniform stretching without being directly torn. When the self-crosslinking active groups include phenylacetylene and benzocyclobutene, the thickness uniformity and tensile strength of the resulting ultrathin PEEK film are slightly improved compared to that with only phenylacetylene. This may be because the self-crosslinking temperature of benzocyclobutene is about 200-280℃, which can stably self-crosslink during polyether ether ketone melt extrusion. Thus, by controlling the benzocyclobutene content in the self-crosslinked polyetherimide, the density of the network crosslinking structure in polyether ether ketone can be stably adjusted, thereby improving the melt strength and processing performance of polyether ether ketone and achieving more uniform and stable stretching and crystallization.
[0088] In addition, because benzocyclobutene has a low self-crosslinking temperature, it is not fully compatible with the processing temperature of polyether ether ketone. If the self-crosslinking active groups in the self-crosslinking polyetherimide only contain benzocyclobutene groups, they have basically been completely reacted during the melt extrusion process of polyether ether ketone. Due to its high content, a high-density self-crosslinking network structure will be formed, which will seriously affect the normal calendering and stretching process of polyether ether ketone. Not only is the traction force required for biaxial stretching greater and the equipment requirements higher, but as the orientation and crystallinity of stretched polyether ether ketone increase, the overall strength will increase accordingly and eventually form a rigid state, which is easy to tear directly and difficult to stretch into a film.
[0089] Based on Examples 3-8 and the data in Table 1, it can be seen that the modification effect of modified nanowhiskers on ultrathin PEEK films varies depending on the composition of the nanowhiskers. When using only a single type of nanowhisker, modified silicon carbide whiskers show the best modification effect, effectively improving the uniformity of film thickness at different thicknesses and further enhancing the tensile strength of ultrathin PEEK films. When a combination of aluminum borate whiskers and potassium titanate whiskers is used, the modification effect is close to that of silicon carbide whiskers. Although there are still some differences in certain properties, the cost of aluminum borate whiskers and potassium titanate whiskers is significantly lower than that of using nanoscale silicon carbide whiskers alone, which helps control production costs.
[0090] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. An ultra-thin PEEK film made by extrusion followed by biaxial stretching, characterized in that: The following raw materials are included by mass: Polyether ether ketone: 100 parts; Self-crosslinking polyetherimide: 5-20 parts; Modified nanowhisker: 0.05-1 part; The self-crosslinking polyetherimide is polyetherimide synthesized from dianhydride monomer, diamine monomer and self-crosslinking functional monomer, the self-crosslinking functional monomer is one of 4-phenyl acetylene phthalic anhydride or a combination of 4-phenyl acetylene phthalic anhydride and 4-amino benzocyclobutene, and the modified nanowhisker is obtained by surface modification treatment of nanometer inorganic whisker with a coupling agent.
2. The ultra-thin PEEK film of claim 1, wherein: The preparation method of the self-crosslinking polyetherimide comprises the following steps: A1, the dianhydride monomer is fully dissolved in anhydrous solvent to obtain an anhydride solution; the diamine monomer is fully dissolved in anhydrous solvent to obtain a diamine solution; and the self-crosslinking functional monomer is fully dissolved in anhydrous solvent to obtain an end-capping agent; A2, under normal temperature, the diamine solution is added to the anhydride solution in multiple times, each time after adding, stirring is required until clarification before continuing to add, after adding, stirring is continued under normal temperature for not less than 12 hours, then the end-capping agent is added, and the reaction is continued under normal temperature for not less than 6 hours, to obtain a pre-polymer solution; the imidization catalyst is added to the pre-polymer solution, heated to 40-60℃ and kept for 1-3 hours to obtain a self-crosslinking polyetherimide solution; A3, the ethanol aqueous solution is pre-cooled to below 5℃ to obtain a precipitate stock solution, then the self-crosslinking polyetherimide solution is added dropwise to the precipitate stock solution under continuous stirring, after dropwise addition, stirring is uniform and standing is performed, the precipitate is separated and collected by high-speed centrifugation, and after washing the precipitate, vacuum drying, crushing and sieving are performed to obtain the self-crosslinking polyetherimide.
3. The ultra-thin PEEK film of claim 2, wherein: The molar ratio of the dianhydride monomer, the diamine monomer and the end-capping agent is 1:1.1-1.2:(0.15-0.25); The dianhydride monomer is a bisphenol A type diether dianhydride; the diamine monomer is a combination of 4,4'-diamino diphenyl ether and 1,4-phenylenediamine, and the molar ratio of the 4,4'-diamino diphenyl ether and the 1,4-phenylenediamine is 1:(1.5-4).
4. The ultra-thin PEEK film of claim 3, wherein: The self-crosslinking functional monomer is a combination of 4-phenyl acetylene phthalic anhydride and 4-amino benzocyclobutene; In A1, the molar ratio of the 4-phenyl acetylene phthalic anhydride and the 4-amino benzocyclobutene in the preparation of the end-capping agent is (1.05-1.1):1, after the 4-phenyl acetylene phthalic anhydride and the 4-amino benzocyclobutene are dissolved in anhydrous solvent, heating to 40-60℃ and stirring reaction for 3-4 hours are required, and the end-capping agent is obtained after cooling.
5. The ultra-thin PEEK film of claim 2, wherein: The imidization catalyst is a combination of triethylamine and acetic anhydride, the molar ratio of the triethylamine and the acetic anhydride is 1:(1-1.5), and the addition amount of the imidization catalyst is 10-12% of the total molar amount of the dianhydride monomer and the diamine monomer.
6. The ultra-thin PEEK film of claim 1, wherein: The nanometer inorganic whisker is at least one of zinc oxide whisker, aluminum borate whisker, potassium titanate whisker or silicon carbide whisker; and the coupling agent is an aluminum-titanium composite coupling agent.
7. The ultra-thin PEEK film of claim 6, wherein: The nanowhisker is a combination of aluminum borate whisker and potassium titanate whisker, and the mass ratio of the aluminum borate whisker to the potassium titanate whisker is 1: (1-2).
8. A method for the preparation of an ultra-thin PEEK film according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: S1, fully mixing the polyether ether ketone, self-crosslinking polyether imide and modified nanowhisker by mass fraction, then melt-extruding the mixed powder through an extruder, calendering the melt flow through a three-roller calender to obtain a primary film; S2, introducing the primary film obtained in S1 into an oven, then sequentially performing preheating, longitudinal stretching, transverse stretching and heat setting in the oven, then cooling, edge cutting and winding to obtain the ultra-thin PEEK film.
9. The method of claim 8, wherein: In the S1, the extruder is four-section region heating, the first region heating temperature is set to 335-340℃, the second region heating temperature is set to 345-360℃, the third region heating temperature is set to 375-380℃, the fourth region heating temperature is 375-385℃, and the extrusion die temperature is set to 380-385℃; The three-roller calender comprises an inlet roller, a main compression roller and an outlet roller, wherein the inlet roller temperature is set to 110-120℃, the main compression roller temperature is set to 100-110℃, and the outlet roller temperature is set to 90-105℃.
10. The method of claim 8, wherein: In the S2, the oven temperature is set to 140-180℃ during preheating, the oven temperature is set to 165-175℃ during longitudinal stretching, and the oven temperature is set to 175-185℃ during transverse stretching.