A PAEK-based composite film containing an additive component and a production method thereof

Abstract

The invention relates to PAEK polymer-based composite films containing ID additives or 2D additives or 3D additives, or hybrid additives thereof, and to a method for producing the same.

Description

[0001] A PAEK-BASED COMPOSITE FILM CONTAINING AN ADDITIVE COMPONENT AND A PRODUCTION METHOD THEREOF

[0002] Technical Field of the Invention

[0003] The present invention relates to the production of PAEK polymer-based composite films containing ID additives or 2D additives or 3D additives, or hybrid additives thereof. The invention also relates to prepreg and composite structures in which the composite films of the invention are produced by surface activation thereof or fiber surface activation thereof, or with a direct fiber reinforcement of the composite films, and to the production methods thereof.

[0004] Background of the Invention

[0005] The fact that thermoplastic films are increasingly adopted in various end-user industries raises attention to the processing and fabrication of materials, especially high-temperature thermoplastic composites. Due to the high crystallinity of the thermoplastic polymers, a number of processing difficulties may arise, especially during film production. In addition, in the production of films containing said thermoplastic materials, shrinkage (casting shrinkage) may occur during the rapid cooling, which has a direct effect on the structure of the final product and reduces the quality of the resulting polymeric film.

[0006] Polymer-based composites are materials that are formed by introducing one or more different types of components into the polymer-based materials and combining the mixture at the macro level. A polymer-based composite may essentially comprise a polymer matrix and additive components contained in the matrix. Such components are generally responsible for increasing the mechanical strength of the polymeric structures, enhancing their thermal properties, improving their electrical properties and / or imparting a new functional property to the polymer.

[0007] A criterion that determines the mechanical, thermal and electrical properties of the final composite material is which additive components are used as reinforcement. In this sense, additive materials should be selected by taking into consideration the desired properties of the composite material. In cases where more than one function is desired in the polymeric composites, the additives selected should be selected in such a way that they do not eliminate each other's effects and, if possible, work in coordination.

[0008] Thermoplastic composite materials are often used in fields such as aviation, energy, electronics, and defense. The need for compact, lightweight materials with improved thermal conductivity is highly critical in overcoming challenges such as localized heat spots and thermal fatigue in applications in these fields.

[0009] Due to heat dissipation, there may be some difficulties in thermoplastic polymer matrices and composite materials containing same. For example, due to the small size of the electronic devices, the heat that is generated in use accumulates in a limited area, and it must be quickly dissipated. Polymer-based films with no reinforcing material cannot overcome high heat flow due to low thermal conductivity, especially when used as an interface material.

[0010] As in electronic applications, high thermal conductivity and electrical insulation are among the required properties in the aviation industry. Due to their structural properties such as high temperature resistance and improved mechanical strength, components from the PAEK group are frequently preferred in the aviation and aerospace industry.

[0011] Polyether ether ketone (PEEK) from the family of polyaryl ether ketones (PAEK) provides outstanding performance in terms of high temperature resistance, heat resistance of up to 200°C, especially for electrical applications, low density, flexibility, insulation, chemical resistance, and dimensional stability. PEEK is a preferred component in fiber-reinforced composites due to its high melting and glass transition temperature and its thermal stability at temperatures exceeding 120°C. In addition, PEEK-based components are lightweight, improved chemical and corrosion resistance, and have a high fatigue strength; however, PEEK- based components suffer from low through-plane thermal conductivity and poor heat dissipation. Especially in environments where high levels of heat are generated, the ability of the PEEK component to dissipate heat in the environment remains weak. PEEK-based composite materials satisfy some of the targeted properties, but they may be inadequate in terms of heat conduction. Apart from PEEK, high-performance poly ether ketone (PEK) and poly ether ketone ketone (PEKK) polymers, which are widely used members of the PAEK family, are also widely used in aviation and space studies. In view of the above requirements, it is apparent that there is a need for high-performance PAEK polymer-based materials with improved thermal conductivity, electrical insulation, mechanical properties, and durability during use.

[0012] Objects of the Invention

[0013] An object of the invention is to provide solutions to the above identified problems in the prior art.

[0014] Another object of the present invention is to increase the through-plane thermal conductivity of the PAEK polymer-based composite films.

[0015] Another object of the present invention is to provide improved electrical insulation of the PAEK polymer-based composite films.

[0016] Another object of the present invention is to obtain PAEK polymer-based composites that offer ease of production and cost advantage and that are also scalable in the industry.

[0017] Another object of the present invention is to obtain PAEK polymer-based composite films with improved mechanical properties, thereby exhibiting the desired hardness and durability characteristics.

[0018] Another object of the present invention is to obtain PAEK polymer-based composite films that provide high thermal stability.

[0019] Another object of the present invention is to increase the lifetime of PAEK polymer-based composites, especially those used in electronic applications.

[0020] Another object of the present invention is to obtain PAEK polymer-based composites that are suitable for recycling.

[0021] Yet another object of the present invention is to obtain materials that effectively dissipate the heat generated by the product in use, in order to ensure a safe operating temperature in high- performance applications, thereby enabling a long component life.

[0022] Summary of the Invention The invention relates to a PAEK polymer-based composite film containing one-dimensional (ID) additives or two-dimensional (2D) additives or three-dimensional (3D) additives, or hybrid additives thereof.

[0023] The invention also discloses that the ID additives used in the PAEK polymer-based composite film are titanium dioxide, silicon oxide, glass fiber, silicon carbide whiskers, or a combination thereof, the 2D additives are hexagonal boron nitride sheets, aluminum oxide sheets, mica, or a combination thereof, and the 3D additives are aluminum oxide, aluminum nitrate, hexagonal boron nitride, or a combination thereof.

[0024] The invention also discloses that the PAEK polymers used in the PAEK polymer-based composite film are selected from PEEK, PEKK, PEK, or a combination thereof.

[0025] The invention also discloses that the nominal thickness of the PAEK polymer-based composite film ranges from 100-500 microns, preferably 130-210 microns, more preferably 200-210 microns.

[0026] The invention also discloses that the weight of the additives (additive components) present in the PAEK polymer-based composite film is in the range of 5-40%, preferably 10-30% by the total weight of the composite film.

[0027] The invention also discloses that the median size of the additive (additive component) particles present in the PAEK polymer-based composite film is in the range of 10nm-50pm.

[0028] The invention also relates to a manufacturing method for obtaining a PAEK polymer-based composite film containing ID additives or 2D additives or 3D additives, or hybrid additives thereof, wherein the polymer-based composite film is produced in a twin-screw extruder or a single-screw extruder.

[0029] The invention also describes a method comprising the steps of feeding an additive component and a PAEK polymer into a twin-screw extruder for producing the PAEK polymer-based composite film, in order to obtain granules containing the additive component and the PAEK, and subjecting the obtained granules to film extrusion to obtain the PAEK polymer-based composite film. The invention also describes a method comprising the steps of mixing a PAEK polymer and an additive component (ID or 2D or 3D, or hybrid additives thereof) in a separate machine for producing the PAEK polymer-based composite film, to obtain granules containing the additive component and the PAEK polymer, feeding the obtained granules to a single-screw extruder, and obtaining an additive-containing PAEK polymer-based composite film by film extrusion.

[0030] Detailed Description of the Invention

[0031] The invention relates to PAEK polymer-based composite films containing ID additives or 2D additives or 3D additives, or hybrid additives thereof. According to the invention, the polymeric composite materials are thermally conductive and electrically insulating. There is an improvement in the through-plane thermal conductivity of the composite films of the invention, enabling the heat contained in the materials comprising the composite film to be easily removed from the environment.

[0032] The through-plane thermal conductivity value of the PAEK polymer-based composite films obtained with the invention may be 0.1-1.0 W / (nrK) at room temperature, wherein the through-plane thermal conductivity may be measured in accordance with IS022007-2 standards.

[0033] According to the invention, PAEK polymer-based composite films contain ID (one-dimensional) additives or 2D (two-dimensional) additives or 3D (three-dimensional) additives, or hybrid additives thereof. The term "additive" may also be referred to as "additive component".

[0034] Due to their polymeric structure, the thermoplastic polymers that are available in the prior art and that can satisfy the required mechanical properties have poor through-plane thermal conductivity. The use of thermoplastic polymers with poor thermal conductivity is limited in the industry and such polymers cannot achieve the targeted performance. In order to eliminate this problem, it has been determined that there is a significant improvement in the thermal properties of the polymer-based composite films obtained by the addition of ID or 2D or 3D additives alone, or their hybrid additives with each other.

[0035] According to another embodiment of the invention, the ID additives include titanium dioxide, silicon oxide, glass fiber, silicon carbide whiskers, or a combination thereof. The 2D additives include hexagonal boron nitride sheets, aluminum oxide sheets, mica, or a combination thereof. The 3D additives include aluminum oxide, aluminum nitrate, hexagonal boron nitride, or a combination thereof. According to the invention, the PAEK polymer-based composite films may only contain ID additives, or 2D additives, or 3D additives, or they may contain binary or ternary combination of ID, 2D, 3D additives.

[0036] According to a preferred embodiment of the invention, hexagonal boron nitride (h-BN) or graphene may be used as an additive material in the PAEK-based composite films; the preferred additive material is h-BN.

[0037] By adding h-BN to PAEK polymer, it is possible to obtain polymeric structures with improved electrical insulation and thermal conductivity.

[0038] According to another embodiment of the invention, the PAEK polymer in the composite film is PEEK, PEKK, PEK, or a combination thereof.

[0039] According to another embodiment of the invention, a PEEK polymer is preferably used in the composite film.

[0040] PEEK is a semi-crystalline polymer with isotropic thermal conductivity, wherein the heat transfer mechanism is mainly driven by phonon transport. Polymeric structures and composite materials containing a PEEK component with low heat transfer properties cannot meet the desired properties in the industry. At this point, according to the invention, h-BN-filled PEEK polymers have been obtained with the addition of h-BN additives to PEEK polymer. A significant increase has been observed in the through-plane thermal conductivity value of h-BN-filled polymeric structures and composite materials. Thus, h-BN-filled PEEK polymers have been identified as a preferred material and composite additive, especially in electronic applications requiring high performance and applications requiring high degrees of thermal conductivity and electrical insulation.

[0041] In addition, with the h-BN additive, an increase has been observed in the degree of crystallinity of the PEEK polymer-based composite film. An increase in the degree of crystallinity helps improve the thermal conductivity of the h-BN-filled PEEK polymeric films. Moreover, thermal degradation behaviors have been analyzed by means of a thermogravimetric analysis, and it has been determined that the h-BN-filled PEEK polymer can withstand high temperatures without any degradation in its structure and can maintain its performance. According to another embodiment of the invention, the nominal thickness of the PAEK polymer- based composite film is in the range of 100-500 microns. In a more preferred embodiment, the nominal thickness of the PAEK polymer-based composite film is in the range of 130-210 microns, and in an even more preferred embodiment, the nominal thickness of the PAEK polymer-based composite film is in the range of 200-210 microns. The width of the the composite film may be in the range of 220-270 microns.

[0042] In an embodiment of the invention, the weight of the additive component may be in the range of 5-40% by the total weight of the composite film.

[0043] According to another embodiment of the invention, the weight of the additive component(s) may be in the range of 10-30% by the total weight of the composite film.

[0044] According to another embodiment of the invention, the median particle size of the additive component particles may be in the range of 10 nm - 50 pm. The "median particle size" is measured in terms of the length of the particles. The median particle size of the additive component particles used in obtaining the polymer-based composite films of the invention is critically important in many aspects, such as the equidimensionality of the granules obtained during the granulation process in the extrusion method applied in the production of the film, and the homogeneity of the composite films obtained therefrom.

[0045] The production of the PAEK polymer-based composite films of the invention is carried out by a casting extrusion method, in which the compound used herein is melted during extrusion.

[0046] The inventive PAEK polymer-based composite films containing ID additives or 2D additives or 3D additives or hybrid additives thereof may be produced in a twin-screw extruder or in a single-screw extruder.

[0047] According to the invention, a method for the manufacturing of the PAEK polymer-based composite film containing ID or 2D or 3D additives or the hybrid additives thereof includes the following steps: feeding a PAEK polymer and an additive component into a twin-screw extruder to obtain granules containing the additive component and the PAEK polymer, and subjecting the obtained granules to a film extrusion process to obtain the PAEK polymer-based composite film.

[0048] According to the invention, the additive component(s) and the PAEK polymer to be used in the first step of the manufacturing method of the composite film are fed into a twin-screw extruder, wherein the additive component / PAEK granules are obtained. In the method, it is possible to introduce a high amount of the additive components into the PAEK polymer matrix. In addition, it has been possible to mix and distribute the components used homogeneously. In the second step of the method, the additive component / PAEK granules are used to obtain an additivecontaining PAEK polymer-based composite film by a film extrusion method.

[0049] The PAEK polymer-based composite films of the invention may also be produced by a singlescrew extrusion process. The method includes the steps of

[0050] - mixing a PAEK polymer and an additive component (ID or 2D or 3D, or the hybrid additives thereof) in a separate machine to obtain additive component-PAEK polymer granules,

[0051] - feeding the obtained granules to a single-screw extruder, and obtaining an additivecontaining PAEK polymer-based composite film by a film extrusion process.

[0052] According to another embodiment of the invention, the twin-screw or single-screw extrusion process may be carried out at a temperature in a range of 400-450°C. The particles of the additive component used cause a more rapid cooling of the polymer material during the extrusion, and due to the inherent lubricating effect of the additive, when added in high amounts, it negatively affects the fluidity and processability of the material. The temperature range is selected by taking into account the melting point of the polymer matrix in order to compensate for the heat loss and to compensate the melt flow index of the composite material.

[0053] According to another embodiment of the invention, a pressure applied in the twin-screw extruder for the manufacturing of the additive-containing PAEK polymer-based composite film may be in the range of 32-38 bar.

[0054] The additive-containing PAEK polymer-based composite film of the invention may be used alone, or together with reinforcement materials such as continuous, discontinuous or short fibers, thereby allowing the production of prepregs or composites. In this way, it is possible to produce high-performance materials with improved thermal properties. According to another embodiment of the invention, the reinforcement materials that can be used with the inventive PAEK polymer-based composite films containing an additive component may be continuous, discontinuous, or mat form of carbon or glass fiber fabrics. The PAEK polymer-based composite films containing an additive component as detailed in the invention may be used to obtain a product in the form of a prepreg or composite by combining them with suitable reinforcement materials.

[0055] In particular, carbon-reinforced thermoplastic composites are gaining popularity in aerospace and aviation applications as well as in the energy industry due to their improved mechanical properties, thermal stability, and recyclability. During their use in high-performance applications, it is necessary to dissipate the heat generated in order to ensure a safe operating temperature; otherwise, heat spots will occur, which may negatively affect the lifetime of the component.

[0056] Carbon or glass fiber fabric-reinforced composite materials including the PAEK polymer-based composite film containing an additive component have found wide application in various industries such as automotive, electronics, machinery, telecommunications, nuclear technology, and aviation.

[0057] According to another embodiment of the invention, in a method for obtaining a prepreg or composite comprising the inventive PAEK polymer-based composite films containing an additive component, the composite film may be combined with a reinforcing component by a hot-pressing method (plasma activation). The reinforcing component used herein may be continuous, discontinuous, or mat form of carbon / glass fiber fabrics .

[0058] The prepreg or composite materials containing the composite films of the invention may be obtained by activating the surface of the composite materials, activating the surface of a carbon or glass fiber fabric, or by producing the composite films with direct fiber reinforcement.

[0059] For example, according to the invention, glass or carbon fiber fabrics may be directly bonded with the composite films of the invention. Another alternative is to activate glass or carbon fiber fabrics by such methods as direct immersion / ultrasonic spraying, thereby increasing the interface adhesion effect. EXAMPLES:

[0060] Example-1:

[0061] Materials:

[0062] A carbon fiber fabric was used as a carbon fiber. Unfilled PEEK polymer granules, known under the trade name Tecopeek PK40 NL, were used as the PEEK component. A powder of hexagonal boron nitride (h-BN) was used as the boron nitride, and the median particle size of h-BN was in the range of 25-30 pm. h-BN-loaded PEEK component:

[0063] The h-BN is fed into a PEEK polymer matrix in a twin-screw extruder at an amount of 30% by weight and granulated therein. L / D ratio of the twin-screw extruder used herein is 40, the screw diameter is 26 mm, and the barrel temperature is set to 400°C - 450°C. After extrusion, a 30 wt.% h-BN-loaded PEEK compound is produced.

[0064] Production of a neat PEEK film and 30 wt% h-BN-filled PEEK composite film:

[0065] Film production from neat PEEK (n-PEEK) and a PEEK polymeric component containing 30 wt% h-BN (30-PEEK) is achieved by a film extrusion process. During the film production, the barrel temperatures of the extruder are kept at 395°C. The extrusion pressure is 7-17 bar for the n- PEEK sample, which is 35 bars for the 30-PEEK sample. The nominal film thickness for n-PEEK and 30-PEEK is 200 pm and 210 pm, respectively.

[0066] Deposition of hBN on carbon fabric bv electrosoraving method:

[0067] A multi-channel electrospraying unit is used to deposit a h-BN solution onto the layers of the carbon fabric by the electrospraying method. In the present experimental setup, samples were formed via electrospraying techniques using dual nozzles. A voltage of 14 kV was applied, maintaining a minimum distance of 7 cm from the nozzle to the fabric substrate. A flow rate of the solution was set at 80 pl / min. A movement speed of the nozzle in the x and y directions was set to 6 mm / s. The electrospraying process includes coating a side of the carbon fibers with the h-BN solution, and then spraying the h-BN solution onto the other side of the fibers via electrospraying method after a drying period for 24 hours at room temperature.

[0068] In order to prepare an h-BN solution for electrospraying onto a carbon fabric substrate, the followings steps are followed: (i) adding 10 g of micron-sized h-BN powder to 100 mL of ethanol solvent,

[0069] (ii) mixing manually for several minutes,

[0070] (iii) stirring magnetically for 1 hour using a magnetic stirrer at room temperature.

[0071] As a result, a loading amount of h-BN was calculated to be 0.12 wt.% based on the carbon fabric.

[0072] Production of a carbon fiber-reinforced hBN-PEEK composite:

[0073] Samples of carbon fiber-reinforced PEEK based composites are produced by a hot-pressing technique. First, the PEEK film and the layers of carbon fabric are placed in a square mold of 300mm x 300mm. Before placing the mold and film / fabric layers, three layers of a semipermanent release film are applied to the top and bottom platens and the mold in order to ensure easy removal of the component after fabrication.

[0074] The process parameters as used during the production of composites are as follows:

[0075] • Holding pressure: 1,5 - 2 MPa

[0076] • Holding temperature: 380°C

[0077] • Molding time: 20 - 25 min

[0078] • Heating and cooling ramp 10°C / min

[0079] After the process, the thickness of the cured laminates is between 2.4 - 2.5 mm.

[0080] The resulting carbon fiber-reinforced h-BN / PEEK composite film has a h-BN loading of 30% by weight. The in-plane thermal conductivity of the h-BN / PEEK polymeric film is calculated to be 2.040 W / (nrK), which provides an increase of 819% compared to the neat PEEK film. The thermal diffusivity of the PEEK polymeric film containing 30% h-BN loading is calculated to be 1.405 mm2 / s, and an increase of 741.31% is observed as compared to the neat PEEK film.

[0081] Thermal conductivity performance of h-BN / PEEK / KF composites:

[0082] The in-plane thermal conductivity of a sample of carbon fiber composites (KF-nPEEK) containing a neat PEEK polymer matrix is 4.852 W / (nrK), and the thermal diffusivity value is 3.277 mm2 / s. The thermal conductivity value of a sample obtained by adding a PEEK polymer matrix containing 30 wt% h-BN additives (KF-30PEEK) into carbon fibers reached 5.914 W / (nrK). In this case, it is calculated that the thermal conductivity of the KF-30PEEK sample increases by 21.88% as compared to the KF-nPEEK sample.

[0083] The thermal diffusivity value of the KF-30PEEK sample reached 3.69 mm2 / s, providing a 12.60% increase in thermal diffusivity compared to the KF-nPEEK sample. Such improvements may be attributed to the additional pathways formed by the h-BN particles between the PEEK matrix and the carbon fiber layers. The mechanism overcomes any intrinsic barriers to heat transfer resulting from phonon-phonon scattering within the PEEK matrix.

Claims

CLAIMS1. A PAEK polymer-based composite film containing one-dimensional (ID) additives or two- dimensional (2D) additives or three-dimensional (3D) additives, or hybrid additives thereof.

2. The polymer-based composite film according to claim 1, wherein the ID additives are titanium dioxide, silicon oxide, glass fiber, silicon carbide whiskers, or a combination thereof.

3. The polymer-based composite film according to claim 1, wherein the 2D additives are hexagonal boron nitride sheets, aluminum oxide sheets, mica, or a combination thereof.

4. The polymer-based composite film according to claim 1, wherein the 3D additives are aluminum oxide, aluminum nitrate, hexagonal boron nitride, or a combination thereof.

5. The polymer-based composite film according to any one of the preceding claims, wherein the PAEK polymers are PEEK, PEKK, PEK, or a combination thereof.

6. The polymer-based composite film according to any one of the preceding claims, wherein the nominal thickness of the film is in the range of 100-500 microns, preferably 130-210 microns, more preferably 200-210 microns.

7. The polymer-based composite film according to any one of the preceding claims, wherein the weight of the additive components is in the range of 5-40%, preferably 10-30% bythe total weight of the composite film.

8. The polymer-based composite film according to any one of the preceding claims, wherein the median size of the additive component particles is in the range of 10 nm- 50pm.

9. A manufacturing method for obtaining a PAEK polymer-based composite film containing ID additives or 2D additives or 3D additives, or the hybrid additives thereof, wherein the polymer- based composite film is produced in a twin-screw extruder or a single-screw extruder.

10. The manufacturing method according to claim 9, wherein the manufacturing method includes the steps of:- feeding an additive component and a PAEK polymer into a twin-screw extruder to obtain granules c comprising the additive component and the PAEK, and- subjecting the obtained granules to film extrusion to obtain the PAEK polymer-based composite film.

11. The manufacturing method according to claim 9, wherein the manufacturing method includes the steps of:- mixing a PAEK polymer and an additive component (ID or 2D or 3D, or the hybrid additives thereof) in a separate machine to obtain the granules of the additive component-PAEK polymer,- feeding the obtained granules to a single-screw extruder, and obtaining an additivecontaining PAEK polymer-based composite film by film extrusion.

12. The manufacturing method according to claims 9-11, characterized in that the twin-screw or single-screw extrusion process is performed at a temperature in a range of 400-450°C.

13. A prepreg material obtained by using a PAEK polymer-based composite film according to claims 1-8 in combination with reinforcement materials comprising continuous, discontinuous, or short fibers.

14. A composite material obtained by using a PAEK polymer-based composite film according to claims 1-8 in combination with reinforcement materials comprising continuous, discontinuous, or short fibers.

15. A prepreg or composite material according to claim 13 or 14, wherein the reinforcement material is carbon or glass fiber.