High performance polypropylene / cyclic olefin copolymer composite and method for preparing the same

Abstract

The application belongs to the technical field of composite materials, and discloses a high-performance polypropylene / cyclic olefin copolymer composite material and a preparation method thereof.The high-performance polypropylene / cyclic olefin copolymer composite material comprises polypropylene resin, cyclic olefin copolymer and propylene-based elastomer, and the amount of the propylene-based elastomer is 2-3% of the total mass of the polypropylene resin and the cyclic olefin copolymer; the preparation method is as follows: the polypropylene resin, the cyclic olefin copolymer and the propylene-based elastomer are blended, then melt-extrusion granulation is carried out, and then compression molding is carried out to obtain the high-performance polypropylene / cyclic olefin copolymer material.The application has the advantages of efficient compatibilization, process simplification and ultra-thin processing adaptability, and not only ensures excellent heat resistance of the blending system, but also perfectly retains inherent low dielectric constant and low dielectric loss characteristics.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology and relates to a high-performance polypropylene / cyclic olefin copolymer composite material and its preparation method. Background Technology

[0002] Thin-film capacitors are core components in emerging fields such as wind power converters, photovoltaic inverters, new energy vehicle inverters, pulse power equipment, silicon carbide semiconductors, and high-voltage direct current transmission. Their performance directly affects the efficiency and reliability of power electronic equipment. Biaxially oriented polypropylene (BOPP) film has long been used as a key dielectric material for thin-film capacitors due to its excellent breakdown resistance, high charge-discharge efficiency, and mature large-scale processing technology. However, the heat resistance limit of traditional BOPP film is 105 °C. When the ambient temperature exceeds this threshold (e.g., the temperature in the engine compartment of a new energy vehicle can reach over 120 °C), the leakage current in its amorphous region increases sharply, leading to a significant decrease in charge-discharge efficiency (η). Simultaneously, the enhanced mobility of high-energy carriers accelerates molecular chain breakage, damaging the electrical breakdown strength (Eb), ultimately causing a decrease in the effective area and capacitance of the capacitor. To cope with high-temperature environments, existing technologies require additional cooling systems, which not only increases equipment space and cost but also reduces overall system efficiency, severely restricting the application of BOPP film in high-temperature, high-reliability scenarios. In fact, this demand for higher heat resistance is not limited to capacitor films, but is a general driving force for the upgrading of polypropylene materials. In the automotive industry, high-temperature modified polypropylene has long been widely used in the manufacture of engine covers, cooling fans, and battery casings for new energy vehicles to achieve lightweighting and cost control under harsh thermal and vibration environments. In the home appliance sector, it is used to manufacture washing machine drums and microwave oven containers to withstand hot water, steam, and high-temperature heating. In the medical field, it forms surgical instrument trays and medicine bottles that can withstand autoclaving. Therefore, whether to overcome the performance bottlenecks of high-end capacitors or to meet the needs of a wider range of industrial sectors, developing a new generation of high-temperature resistant polypropylene materials has become a crucial frontier topic in materials science and engineering.

[0003] To overcome the heat resistance bottleneck of BOPP films, cyclic olefin copolymers (COCs) have become a preferred modifying material for improving the heat resistance of PP-based films due to their high transparency, high heat resistance, and dielectric properties similar to polypropylene (PP). Existing technologies attempt to construct blend systems with both high-temperature stability and low dielectric loss by introducing COC into the PP matrix. However, in actual industrialization, the differences in molecular structure between PP and COC (such as...) Figure 1 The thermodynamic incompatibility (as shown) has always been a technical challenge, specifically manifested in the following known technical solutions:

[0004] A patent with authorization announcement number CN110914939A discloses a thin-film capacitor that uses a direct physical blend of PP and COC. However, due to the significant differences in the molecular chain conformation (PP has linear aliphatic chains, while COC contains rigid cyclic olefin structures) and sequence structure between the two, the blend system exhibits strong thermodynamic incompatibility. During melt processing, phase separation easily occurs, forming a coarse and unevenly distributed COC dispersed phase, and the interfacial bonding between the two phases is weak. This microstructural defect not only becomes a weak point for electrical breakdown and mechanical failure but also leads to surface wrinkles and optical inhomogeneities in the thin film, making it difficult to meet the stringent requirements of ultra-thin capacitors for film thickness (3~15μm) and structural uniformity.

[0005] Patent application CN117659563A discloses a method for preparing high-temperature resistant polypropylene film for capacitors. It innovatively employs a "COC / SEBS masterbatch" pretreatment process, improving the compatibility of PP / COC through the physical compatibilizing effect of SEBS (hydrogenated styrene-butadiene-styrene block copolymer). However, the polystyrene (PS) hard segments at the ends of the SEBS molecular chains are inherently incompatible with the aliphatic structures of PP and COC due to their polar structure. Their interfacial bonding mainly relies on weak van der Waals forces or physical adsorption, limiting the interfacial strength. Furthermore, SEBS improves processability by lowering the glass transition temperature (Tg) of COC, which weakens the contribution of COC to the system's heat resistance, fundamentally contradicting the initial intention of heat-resistant modification.

[0006] Patent application CN118165421A discloses a polypropylene composite material, a polypropylene film, and a polypropylene capacitor film. This method utilizes a pre-crosslinked "salami structure" constructed from EPDM (ethylene propylene diene monomer) and COC to enhance interfacial bonding. However, the interfacial bonding between EPDM and the PP matrix primarily relies on the physical entanglement of molecular chains. Under high temperature or high stress conditions, chain segment slippage can easily occur, leading to interfacial debonding and performance degradation. Furthermore, residual crosslinking agents can interfere with molecular chain alignment, forming wrinkles on the film surface and affecting smoothness. In addition, this method requires the addition of a relatively high dose of EPDM (e.g., 4.5% when the COC content is 7.5%), increasing cost and process complexity.

[0007] In summary, existing technologies generally improve PP / COC compatibility by introducing general-purpose compatibility enhancers such as SEBS and EPDM. However, the molecular structures of these compatibility enhancers are not specifically designed for the molecular chain conformations and sequence characteristics of PP and COC, resulting in insufficient interfacial matching and difficulty in achieving stable compatibility enhancement at the molecular scale. Furthermore, the introduction of new components (such as PS segments and crosslinking agents) often leads to problems such as weakened heat resistance, surface wrinkles, and complex processes. More importantly, the minimum film thickness prepared by existing methods is usually limited to above 6 μm, which cannot meet the stringent performance requirements of current high-end applications (such as ultrathin capacitors and miniaturized electronic devices) for 3 μm-level ultrathin films.

[0008] Therefore, there is a need for a high-performance polypropylene / cyclic olefin copolymer composite material and its preparation method, in order to prepare a high-performance polypropylene / cyclic olefin copolymer composite material that combines efficient compatibilization, simplified process and ultra-thin processing adaptability. Summary of the Invention

[0009] The purpose of this invention is to address the problems existing in the prior art and to provide a high-performance polypropylene / cyclic olefin copolymer composite material and its preparation method.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A high-performance polypropylene / cyclic olefin copolymer composite material includes polypropylene resin, cyclic olefin copolymer, and propylene-based elastomer (PBE). The amount of propylene-based elastomer is 2-3% of the total mass of polypropylene resin and cyclic olefin copolymer, which is significantly lower than the amount added when using compatibilizers such as EPDM in the prior art. This avoids the negative interference of excessive compatibilizer on the thermal properties of the PP / COC blend system, ensuring the excellent heat resistance of the blend system, while perfectly retaining its inherent low dielectric constant (Dk) and low dielectric loss (Df) characteristics.

[0012] PBE contains ethylene and isotactic propylene structural units in its chain, thus exhibiting good compatibility with vinyl COC and isotactic PP, and can be used as a compatibilizer in PP / COC blend systems. In contrast, POE, commonly used in existing technologies, is a random copolymer formed by the catalytic polymerization of ethylene and α-olefins (typically 1-butene, 1-hexene, or 1-octene), lacking isotactic propylene structural units, and therefore cannot be used in PP / COC blend systems to improve compatibility.

[0013] The melt processing window and melt viscosity of PBE are highly compatible with those of PP / COC. This ensures that the three components can melt synchronously and flow uniformly during the blending extrusion process to form a stable melt. In other words, the compatibilizer can directly participate in the blending process and is fully compatible with existing polypropylene film production processes. While achieving efficient compatibilization, it effectively simplifies the process and reduces the overall production cost.

[0014] As a preferred technical solution:

[0015] The high-performance polypropylene / cyclic olefin copolymer composite material described above uses homopolymer polypropylene as the polypropylene resin and has a melt flow rate of 0.2~20.0 g / 10min, preferably 3.0 g / 10min.

[0016] The high-performance polypropylene / cyclic olefin copolymer composite material described above, based on the total mass of polypropylene resin and cyclic olefin copolymer, has a polypropylene resin content of 60-90%, preferably 70-90%, and a cyclic olefin copolymer content of 10-40%, preferably 10-30%.

[0017] The high-performance polypropylene / cyclic olefin copolymer composite material described above, wherein the cyclic olefin copolymer is a copolymer of ethylene and norbornene, has a melt flow rate of 0.5~70 g / 10min, preferably 4.0 g / 10min.

[0018] The high-performance polypropylene / cyclic olefin copolymer composite material described above has a cyclic olefin copolymer uniformly dispersed in polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.18~0.62 μm with no obvious agglomeration. The dispersed phase size is reduced by 33~42% compared with the PP / COC system without added PBE.

[0019] The high-performance polypropylene / cyclic olefin copolymer composite material described above is an ultrathin film with a thickness of no more than 3 μm.

[0020] The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 90~150 ℃, a tensile strength of 32.8~37.8 MPa, an elongation at break of 80~265%, and a notched impact strength of 4.1~5.1 KJ / m. 2This invention maintains the original high rigidity and high tensile strength of the PP / COC system and fully preserves the high Tg (heat resistance) of COC. Furthermore, the dielectric constant and dielectric loss of the high-performance polypropylene / cyclic olefin copolymer composite material of this invention are superior to those of PP / COC systems with compatibilizers such as SEBS and EPDM. The styrene (S) blocks in the SEBS molecular chain contain polar groups (benzene rings), which lead to significant dipole polarization losses under high-frequency electric fields, causing a sharp increase in dielectric loss (Df) and severely deteriorating the high-frequency performance of the material. Therefore, it is unsuitable for demanding dielectric applications. Although EPDM itself is non-polar, its introduction and dispersion often require more complex processes or the addition of additives (such as peroxides) for crosslinking to enhance the interface. These additional process steps and additive residues can easily introduce polar impurities, thereby damaging the pure dielectric environment of the film.

[0021] The present invention also provides a method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material as described above, wherein polypropylene resin, cyclic olefin copolymer and propylene-based elastomer are blended, melt extruded and granulated, and then molded to obtain a high-performance polypropylene / cyclic olefin copolymer composite material.

[0022] As a preferred technical solution:

[0023] The method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material as described above involves drying the polypropylene resin and the cyclic olefin copolymer separately in a vacuum oven before blending. The drying temperature for the polypropylene resin is 60-70 °C for 1-2 h, and the drying temperature for the cyclic olefin copolymer is 80-100 °C for 3-5 h.

[0024] The preparation method of the high-performance polypropylene / cyclic olefin copolymer composite material described above involves a blending time of 10-20 min and a melt extrusion granulation temperature of 230-260 ℃.

[0025] The preparation method of the high-performance polypropylene / cyclic olefin copolymer composite material described above uses a flat vulcanizing machine for molding. The temperature of the flat vulcanizing machine is 240~260 ℃, preferably 250~260 ℃.

[0026] Invention principle:

[0027] The existing technology discloses that PBE is mainly used as a compatibilizer in PP / PE systems. PBE mainly acts as a "bridge," utilizing the propylene and ethylene segments in its molecular chain to form simple physical entanglements with the two phases. These entanglements are prone to slippage and decoupling under high temperature or high-ratio stretching.

[0028] PP is a semi-crystalline linear polymer, while COC is a completely amorphous copolymer with a rigid cyclic structure. Significant differences in chemical structure and crystallization behavior between PP and COC result in a much higher interfacial tension in PP / COC compared to the PP / PE system, making them thermodynamically incompatible. In this situation, compatibilizers used in PP / PE systems typically cannot migrate to the PP / COC system. Furthermore, when PBE is used in PP / PE systems, the addition amount is typically 5–20 wt%. When the addition amount is less than 5%, the enrichment concentration of the compatibilizer at the interface is too low to form an interface with sufficient thickness and strength capable of transmitting stress. This interfacial region becomes a mechanically weak point in the material. Under external forces, due to low stress transmission efficiency, interfacial debonding easily occurs instead of matrix yielding or creasing, thus failing to achieve a toughening effect.

[0029] However, this invention unexpectedly discovered that in extremely incompatible systems like PP / COC, adding 2-3% PBE as a compatibilizer exhibits a unique mechanism not disclosed or possessed by existing technologies: due to the presence of the COC phase, the propylene segments in the PBE molecular chain can form efficient co-crystallization with the PP matrix, inducing the formation of a more regular layered structure or epitaxial crystallization, thereby establishing a stable physical anchor point in the semi-crystalline PP phase; simultaneously, the random ethylene segments in PBE can achieve interfacial wetting and physical entanglement with the amorphous COC region. Through this dual anchoring effect (i.e., co-crystallization with PP and interfacial entanglement with COC), PP and COC have a relatively stable interface.

[0030] Unmodified PP / COC blends contain large, weakly bonded COC phase regions, which become stress concentration points and natural defects during film stretching. Therefore, such blends cannot be stably stretched to prepare ultrathin films on the 3 μm scale and are prone to breakage or pore formation. The addition of PBE, however, refines the COC dispersion phase and firmly anchors it within the PP matrix, eliminating these defects. This results in a more uniform and continuous material, allowing stress to be evenly transferred and dispersed during stretching.

[0031] Beneficial effects:

[0032] (1) The PBE chain used in this invention contains ethylene and isotactic propylene structural units, so it has good compatibility with vinyl COC and isotactic PP. Moreover, the propylene-based elastomer can significantly improve interfacial compatibility with a small amount, reduce the particle size of the dispersed phase, and improve the toughness of the material. This avoids the precipitation, crosslinking side reactions, and film surface wrinkling problems that may be caused by traditional high-dose or reactive compatibilizers. This is beneficial for preparing flat ultrathin films with a thickness of less than 3 μm, and solves the drawbacks of coarse dispersed phase and film morphology defects caused by thermodynamic incompatibility between PP and COC in the prior art.

[0033] (2) The melt processing window and melt viscosity of PBE in this invention are highly matched with those of PP / COC. This ensures that the three components can melt synchronously and flow uniformly during the blending extrusion process to form a stable melt. That is, the compatibilizer can directly participate in the blending and is fully compatible with the existing polypropylene film production process. While achieving efficient compatibilization, it effectively simplifies the process and reduces the overall production cost, solving the problem of high industrialization difficulty and high cost caused by the complexity of existing compatibilization technologies (such as SEBS and EPDM compatibilization).

[0034] (3) Thanks to the efficient capacity-enhancing effect of PBE, the amount of PBE added in this invention is relatively small, which also avoids the negative interference of excessive capacity enhancer on the thermal performance of the PP / COC blend system, ensuring the excellent heat resistance of the blend system, while perfectly preserving its inherent low dielectric constant (Dk) and low dielectric loss (Df) characteristics. This solves the problem that the existing technology is limited in its application in key fields such as high-end electronic components and film capacitors due to the degradation of electrical performance under high temperature environment. Attached Figure Description

[0035] Figure 1 This is a schematic diagram illustrating the differences in molecular structure between PP and COC in the prior art; in the figure, a is the general molecular structure formula of COC, b is the general molecular structure formula of PP, c is the general molecular structure formula of SEBS, d is the general molecular structure formula of EDPM, and e is the general molecular structure formula of PBE.

[0036] Figure 2 This is an electron microscope image of the polypropylene / cyclic olefin copolymer composite material prepared in Example 1 of the present invention;

[0037] Figure 3 This is an electron microscope image of the polypropylene / cyclic olefin copolymer composite material prepared in Example 2 of the present invention;

[0038] Figure 4 This is an electron microscope image of the polypropylene / cyclic olefin copolymer composite material prepared in Example 3 of the present invention;

[0039] Figure 5This is an electron microscope image of the polypropylene / cyclic olefin copolymer composite material prepared in Comparative Example 1 of the present invention;

[0040] Figure 6 This is an electron microscope image of the polypropylene / cyclic olefin copolymer composite material prepared in Comparative Example 2 of the present invention;

[0041] Figure 7 This is an electron microscope image of the polypropylene / cyclic olefin copolymer composite material prepared in Comparative Example 3 of the present invention. Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0043] The manufacturers and brands mentioned in the following embodiments are merely examples. The core of this invention lies in the technical solution itself, and it is not intended to limit specific manufacturers or brands. Products from other manufacturers and brands that meet the technical requirements and performance indicators specified in this invention can also meet the application requirements of this invention and are all feasible choices.

[0044] The test methods for the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0045] Average dispersed phase size: The average dispersed phase size of the sample was determined in accordance with GB / T 42208-2022 standard.

[0046] Heat distortion temperature: The dried melt extrusion granulated products from each embodiment were first injection molded using an injection molding machine to obtain specimens. Then, the heat distortion temperature of the specimens was measured according to ASTM D648 standard. The load was 0.45 MPa, and the three temperature ranges of the injection molding machine were 240 ℃, 250 ℃, and 260 ℃, respectively.

[0047] Tensile strength and elongation at break: The dried melt extrusion granulated products from each embodiment were first injection molded into dumbbell-shaped specimens using an injection molding machine. Then, tensile tests were performed on the specimens according to ASTM D638 standard to obtain tensile strength and elongation at break. The three temperature ranges of the injection molding machine were 240 ℃, 250 ℃, and 260 ℃, respectively.

[0048] Notched impact strength: The dried melt extrusion granulated products from each embodiment were first injection molded using an injection molding machine to obtain notched specimens. Then, the notched impact strength of the specimens was tested according to ASTM D256 standard. The three temperature ranges of the injection molding machine were 240 ℃, 250 ℃, and 260 ℃, respectively.

[0049] Dielectric constant and dielectric loss: The dielectric constant and dielectric loss of the specimens were determined according to ASTM D150 standard; the frequency range was 1 kHz to 1 MHz.

[0050] Example 1

[0051] A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material, comprising the following steps:

[0052] (1) The polypropylene resin and the cyclic olefin copolymer were dried separately: the polypropylene resin (homopolymer polypropylene, melt flow rate of 3 g / 10 min, manufacturer: China Petroleum & Chemical Corporation, grade: PPH-T03-H) was dried in a vacuum oven at 60 °C for 1 h; the cyclic olefin copolymer (polymer of ethylene and norbornene, melt flow rate of 4 g / 10 min, manufacturer: Polyplastics Co., Ltd., grade: TOPAS6015) was dried in a vacuum oven at 80 °C for 3 h.

[0053] (2) Polypropylene resin, cyclic olefin copolymer and propylene-based elastomer (manufacturer: ExxonMobil, brand name: Vistamaxx™ 6102) were blended for 15 min. The resulting mixture was then added to a twin-screw extruder and melt-extruded into granules at 260 °C. The granules were then pelletized by a pelletizer and dried in an oven at 80 °C for 3 h. The proportion of polypropylene resin was 90% based on the total mass of polypropylene resin and cyclic olefin copolymer. The amount of propylene-based elastomer was 2% of the total mass of polypropylene resin and cyclic olefin copolymer.

[0054] (3) The dried blended granules are spread in a template with a thickness of 0.1 mm and a side length of 4 cm, fixed with a polyimide film and an iron plate, and then placed in a flat vulcanizing machine with a temperature of 260 ℃ for both the upper and lower plates. After preheating for 5 min, the pressure is increased to 11 MPa, and finally the pressure is held for 5 min to obtain an ultra-thin film with a thickness of 3 μm. After cooling it at 25 ℃ for 15 min, a high-performance polypropylene / cyclic olefin copolymer composite material is obtained.

[0055] The final high-performance polypropylene / cyclic olefin copolymer composite material (its electron micrograph is shown in Figure 1) was obtained. Figure 2 (As shown) the cyclic olefin copolymer is uniformly dispersed in polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.18 μm;

[0056] The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 90 ℃, a tensile strength of 32.8 MPa, an elongation at break of 265%, and a notched impact strength of 5.1 KJ / m. 2The dielectric constant is 2.9 and the dielectric loss is 3.84 × 10⁻⁶. -4 .

[0057] Comparative Example 1

[0058] A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material is basically the same as in Example 1, except that: in step (2), the addition of propylene-based elastomer is omitted, and only polypropylene resin and cyclic olefin copolymer are blended.

[0059] The thickness of the ultrathin film obtained after pressure holding in step (3) is 10 μm.

[0060] The final high-performance polypropylene / cyclic olefin copolymer composite material (its electron micrograph is shown in Figure 1) was obtained. Figure 5 (As shown) the cyclic olefin copolymer is dispersed in polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.27 μm;

[0061] The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 92℃, a tensile strength of 32.3 MPa, an elongation at break of 195%, and a notched impact strength of 4.7 KJ / m. 2 The dielectric constant is 2.38, and the dielectric loss is 3.72 × 10⁻⁶. -4 .

[0062] Comparing Comparative Example 1 and Example 1, it can be seen that the high-performance polypropylene / cyclic olefin copolymer composite material prepared in this comparative example has a large dispersed phase size and poor toughness. This is because PP and COC have significant differences in molecular structure, and the interfacial bonding depends only on weak van der Waals forces, resulting in a coarse and unevenly distributed COC dispersed phase. Under stress, the interface is prone to debonding, and the material exhibits brittle fracture.

[0063] Example 2

[0064] A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material, comprising the following steps:

[0065] (1) The polypropylene resin and the cyclic olefin copolymer were dried separately: the polypropylene resin (homopolymer polypropylene, melt flow rate of 3g / 10min, manufacturer: Sinopec Oil & Chemical Co., Ltd., grade: PPH-T03-H) was dried in a vacuum oven at 60℃ for 1h; the cyclic olefin copolymer (polymer of ethylene and norbornene, melt flow rate of 4g / 10min, manufacturer: Polyplastics Co., Ltd., grade: TOPAS6015) was dried in a vacuum oven at 80℃ for 3h.

[0066] (2) Polypropylene resin, cyclic olefin copolymer and propylene-based elastomer (manufacturer: ExxonMobil, brand name: Vistamaxx™ 6102) were blended for 15 min. The resulting mixture was then added to a twin-screw extruder and melt-extruded into granules at 260°C. After being pelletized by a pelletizer, the blended granules were dried in an oven at 80°C for 3 h. The proportion of polypropylene resin was 80% based on the total mass of polypropylene resin and cyclic olefin copolymer. The amount of propylene-based elastomer was 2% of the total mass of polypropylene resin and cyclic olefin copolymer.

[0067] (3) The dried blended granules are spread in a template with a thickness of 0.1 mm and a side length of 4 cm, fixed with a polyimide film and an iron plate, and then placed in a flat vulcanizing machine with a temperature of 260 ℃ for both the upper and lower plates. After preheating for 5 min, the pressure is increased to 11 MPa, and finally the pressure is held for 5 min to obtain an ultra-thin film with a thickness of 3 μm. After cooling it at 25 ℃ for 15 min, a high-performance polypropylene / cyclic olefin copolymer composite material is obtained.

[0068] The final high-performance polypropylene / cyclic olefin copolymer composite material (its electron micrograph is shown in Figure 1) was obtained. Figure 3 (As shown) the cyclic olefin copolymer is uniformly dispersed in polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.32 μm;

[0069] The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 115 ℃, a tensile strength of 34.6 MPa, an elongation at break of 180%, and a notched impact strength of 4.7 KJ / m. 2 The dielectric constant is 3.16 and the dielectric loss is 4.32 × 10⁻⁶. -4 .

[0070] Comparative Example 2

[0071] A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material is basically the same as in Example 2, except that: in step (2), the addition of propylene-based elastomer is omitted, and only polypropylene resin and cyclic olefin copolymer are blended.

[0072] The thickness of the ultrathin film obtained after pressure holding in step (3) is 10 μm.

[0073] The final high-performance polypropylene / cyclic olefin copolymer composite material (its electron micrograph is shown in Figure 1) was obtained. Figure 6 (As shown) the cyclic olefin copolymer is uniformly dispersed in polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.56 μm;

[0074] The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 118.55 ℃, a tensile strength of 33.2 MPa, an elongation at break of 120%, and a notched impact strength of 4.1 KJ / m. 2 The dielectric constant is 2.57 and the dielectric loss is 4.27 × 10⁻⁶. -4 .

[0075] Comparing Comparative Example 2 and Example 2, it can be seen that the high-performance polypropylene / cyclic olefin copolymer composite material prepared in this comparative example has a large dispersed phase size and poor toughness. This is because the molecular structures of PP and COC are significantly different, and the interfacial bonding depends only on weak van der Waals forces, resulting in a coarse and unevenly distributed COC dispersed phase. Under stress, the interface is prone to debonding, and the material exhibits brittle fracture.

[0076] Example 3

[0077] A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material, comprising the following steps:

[0078] (1) The polypropylene resin and the cyclic olefin copolymer were dried separately: the polypropylene resin (homopolymer polypropylene, melt flow rate of 3 g / 10 min, manufacturer: China Petroleum & Chemical Corporation, grade: PPH-T03-H) was dried in a vacuum oven at 60 °C for 1 h; the cyclic olefin copolymer (polymer of ethylene and norbornene, melt flow rate of 4 g / 10 min, manufacturer: Polyplastics Co., Ltd., grade: TOPAS6015) was dried in a vacuum oven at 80 °C for 3 h.

[0079] (2) Polypropylene resin, cyclic olefin copolymer and propylene-based elastomer (manufacturer: ExxonMobil, brand name: Vistamaxx™ 6102) were blended for 15 min. The resulting mixture was then added to a twin-screw extruder and melt-extruded into granules at 260 °C. After being pelletized by a pelletizer, the blended granules were dried in an oven at 80 °C for 3 h. The proportion of polypropylene resin was 70% based on the total mass of polypropylene resin and cyclic olefin copolymer, and the amount of propylene-based elastomer was 2% of the total mass of polypropylene resin and cyclic olefin copolymer.

[0080] (3) The dried blended granules are spread in a template with a thickness of 0.1 mm and a side length of 4 cm, fixed with a polyimide film and an iron plate, and then placed in a flat vulcanizing machine with a temperature of 260℃ for both the upper and lower plates. After preheating for 5 min, the pressure is increased to 11 MPa, and finally the pressure is held for 5 min to obtain an ultra-thin film with a thickness of 3 μm. After cooling it at 25 ℃ for 15 min, a high-performance polypropylene / cyclic olefin copolymer composite material is obtained.

[0081] The final high-performance polypropylene / cycloolefin copolymer composite material (its electron micrograph is shown in Figure 1) was obtained. Figure 4 (As shown) the cyclic olefin copolymer is uniformly dispersed in polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.62 μm;

[0082] The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 150 ℃, a tensile strength of 37.8 MPa, an elongation at break of 80%, and a notched impact strength of 4.2 KJ / m. 2 The dielectric constant is 3.20, and the dielectric loss is 4.91 × 10⁻⁶. -4 .

[0083] Comparative Example 3

[0084] A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material is basically the same as in Example 3, except that: in step (2), the addition of propylene-based elastomer is omitted, and only polypropylene resin and cyclic olefin copolymer are blended.

[0085] The thickness of the ultrathin film obtained after pressure holding in step (3) is 10 μm.

[0086] In the final high-performance polypropylene / cyclic olefin copolymer composite material, the cyclic olefin copolymer is uniformly dispersed in the polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 1.01 μm.

[0087] High-performance polypropylene / cyclic olefin copolymer composite material (its electron micrograph is shown in Figure 1) Figure 7 The heat distortion temperature (shown) is 153.3 ℃, the tensile strength is 37 MPa, the elongation at break is 31%, and the notched impact strength is 3.7 KJ / m. 2 The dielectric constant is 2.71, and the dielectric loss is 4.87 × 10⁻⁶. -4 .

[0088] Comparing Comparative Example 3 and Example 3, it can be seen that the high-performance polypropylene / cyclic olefin copolymer composite material prepared in this comparative example has a large dispersed phase size and poor toughness. This is because PP and COC have significant differences in molecular structure, and the interfacial bonding depends only on weak van der Waals forces, resulting in a coarse and unevenly distributed COC dispersed phase. Furthermore, the interface is prone to debonding under stress, and the material exhibits brittle fracture.

[0089] Comparative Example 4

[0090] A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material is basically the same as in Example 3, except that the propylene-based elastomer in step (2) is replaced with an equal mass of POE (manufacturer: Dow Chemical Company, grade 8150).

[0091] The thickness of the ultrathin film obtained after pressure holding in step (3) is 8 μm.

[0092] In the final high-performance polypropylene / cyclic olefin copolymer composite material, the cyclic olefin copolymer is uniformly dispersed in the polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.84 μm.

[0093] The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 144 ℃, a tensile strength of 36.7 MPa, an elongation at break of 51%, and a notched impact strength of 3.9 KJ / m. 2 .

[0094] Comparing Comparative Example 4 and Example 3, it can be seen that the COC dispersed phase in the high-performance polypropylene / cyclic olefin copolymer composite material prepared in this comparative example has a larger size and poorer distribution uniformity, and the heat distortion temperature and notched impact strength are reduced. This is because although ordinary POE has ethylene segments that are compatible with COC, it lacks isotactic propylene sequences that match the structure of the PP matrix. The interfacial bonding mainly relies on physical entanglement, and the compatibilization efficiency is lower than that of PBE.

[0095] Comparative Example 5

[0096] A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material is basically the same as in Example 3, except that the propylene-based elastomer in step (2) is replaced with an equal mass of SEBS (manufacturer: Zhejiang Zhongli Synthetic Co., Ltd., grade: ZL-S6554).

[0097] The thickness of the ultrathin film obtained after pressure holding in step (3) is 8 μm.

[0098] In the final high-performance polypropylene / cyclic olefin copolymer composite material, the cyclic olefin copolymer is uniformly dispersed in the polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.74 μm.

[0099] The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 145 ℃, a tensile strength of 37 MPa, an elongation at break of 49%, and a notched impact strength of 4.0 KJ / m. 2 The dielectric constant is 3.5 and the dielectric loss is 2 × 10⁻⁶. -3 .

[0100] Comparing Comparative Example 5 and Example 3, it can be seen that the high-performance polypropylene / cyclic olefin copolymer composite material prepared in this comparative example has reduced elongation at break and notched impact strength, and significantly increased dielectric constant and dielectric loss. This is because although the ethylene-butene (EB) segment at the end of the SEBS molecular chain has a certain compatibilizing effect, it is inherently incompatible with PP / COC thermodynamically. Furthermore, the benzene ring structure introduced by the styrene (S) segment will generate dipole relaxation under a high-frequency electric field, leading to the deterioration of dielectric properties.

[0101] Comparative Example 6

[0102] A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material is basically the same as in Example 3, except that the propylene-based elastomer in step (2) is replaced with an equal mass of EPDM (manufacturer: Nanjing Sutai Polymer Technology Co., Ltd., grade: g-18).

[0103] The thickness of the ultrathin film obtained after pressure holding in step (3) is 10 μm.

[0104] In the final high-performance polypropylene / cyclic olefin copolymer composite material, the cyclic olefin copolymer is uniformly dispersed in the polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.87 μm.

[0105] The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 144 ℃, a tensile strength of 36.8 MPa, an elongation at break of 42%, and a notched impact strength of 4.1 KJ / m. 2 .

[0106] Comparing Comparative Example 6 with Example 1, it can be seen that the high-performance polypropylene / cyclic olefin copolymer composite material prepared in this comparative example has reduced elongation at break and notched impact strength, and its cyclic olefin copolymer dispersed phase size has increased significantly. This is because the propylene segments of EPDM are randomly distributed, and the interfacial bonding force with the matrix isotactic PP is weak, resulting in its compatibilization and toughening efficiency being much lower than that of PBE.

[0107] Example 4

[0108] A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material, comprising the following steps:

[0109] (1) The polypropylene resin and the cyclic olefin copolymer were dried separately: the polypropylene resin (homopolymer polypropylene, melt flow rate of 3 g / 10 min, manufacturer: Sinopec Oil & Chemical Co., Ltd., grade: PPH-T03-H) was dried in a vacuum oven at 70 °C for 2 h; the cyclic olefin copolymer (polymer of ethylene and norbornene, melt flow rate of 4 g / 10 min, manufacturer: Polyplastics Co., Ltd., grade: TOPAS6015) was dried in a vacuum oven at 90 °C for 5 h.

[0110] (2) Polypropylene resin, cyclic olefin copolymer and propylene-based elastomer (manufacturer: ExxonMobil, brand name: Vistamaxx™ 6102) were blended for 10 min. The resulting mixture was then added to a twin-screw extruder and melt-extruded into granules at 250 °C. After being pelletized by a pelletizer, the blended granules were dried in an oven at 80 °C for 3 h. The proportion of polypropylene resin was 70% based on the total mass of polypropylene resin and cyclic olefin copolymer, and the amount of propylene-based elastomer was 3% of the total mass of polypropylene resin and cyclic olefin copolymer.

[0111] (3) The dried blended granules are spread in a template with a thickness of 0.1 mm and a side length of 4 cm, fixed with a polyimide film and an iron plate, and then placed in a flat vulcanizing machine with a temperature of 260 ℃ for both the upper and lower plates. After preheating for 5 min, the pressure is increased to 11 MPa, and finally the pressure is held for 5 min to obtain an ultra-thin film with a thickness of 2 μm. After cooling it at 25 ℃ for 15 min, a high-performance polypropylene / cyclic olefin copolymer composite material is obtained.

[0112] In the final high-performance polypropylene / cyclic olefin copolymer composite material, the cyclic olefin copolymer is uniformly dispersed in the polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.59 μm.

[0113] The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 145.45 ℃, a tensile strength of 37 MPa, an elongation at break of 90%, and a notched impact strength of 4.1 KJ / m. 2 The dielectric constant is 3.24, and the dielectric loss is 5.01 × 10⁻⁶. -4 .

[0114] Example 5

[0115] A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material, comprising the following steps:

[0116] (1) The polypropylene resin and the cyclic olefin copolymer were dried separately: the polypropylene resin (homopolymer polypropylene, melt flow rate of 3 g / 10 min, manufacturer: China Petroleum & Chemical Corporation, grade: PPH-T03-H) was dried in a vacuum oven at 60 °C for 2 h; the cyclic olefin copolymer (polymer of ethylene and norbornene, melt flow rate of 4 g / 10 min, manufacturer: Polyplastics Co., Ltd., grade: TOPAS6015) was dried in a vacuum oven at 100 °C for 4 h.

[0117] (2) Polypropylene resin, cyclic olefin copolymer and propylene-based elastomer (manufacturer: ExxonMobil, brand name: Vistamaxx™ 6102) were blended for 20 min. The resulting mixture was then added to a twin-screw extruder and melt-extruded into granules at 230 °C. After being pelletized by a pelletizer, the blended granules were dried in an oven at 80 °C for 3 h. The proportion of polypropylene resin was 70% based on the total mass of polypropylene resin and cyclic olefin copolymer. The amount of propylene-based elastomer was 2.5% of the total mass of polypropylene resin and cyclic olefin copolymer.

[0118] (3) The dried blended granules are spread in a template with a thickness of 0.1 mm and a side length of 4 cm, fixed with a polyimide film and an iron plate, and then placed in a flat vulcanizing machine with a temperature of 250 ℃ for both the upper and lower plates. After preheating for 5 min, the pressure is increased to 11 MPa, and finally the pressure is held for 5 min to obtain an ultra-thin film with a thickness of 2 μm. After cooling it at 25 ℃ for 15 min, a high-performance polypropylene / cyclic olefin copolymer composite material is obtained.

[0119] In the final high-performance polypropylene / cyclic olefin copolymer composite material, the cyclic olefin copolymer is uniformly dispersed in the polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.61 μm.

[0120] The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 147.25 ℃, a tensile strength of 37.2 MPa, an elongation at break of 86.2%, and a notched impact strength of 4.2 KJ / m. 2 The dielectric constant is 3.22, and the dielectric loss is 4.97 × 10⁻⁶. -4 .

Claims

1. A high-performance polypropylene / cyclic olefin copolymer composite material, characterized in that: It includes polypropylene resin, cyclic olefin copolymer and propylene-based elastomer, with the amount of propylene-based elastomer being 2-3% of the total mass of polypropylene resin and cyclic olefin copolymer; The grade of the propylene-based elastomer is Vistamaxx™ 6102; Based on the total mass of polypropylene resin and cyclic olefin copolymer, the proportion of polypropylene resin is 60-90%; The cyclic olefin copolymer is uniformly dispersed in polypropylene resin, and the average dispersed phase size of the cyclic olefin copolymer is 0.18~0.62 μm; The high-performance polypropylene / cyclic olefin copolymer composite material is an ultrathin film with a thickness of no more than 3 μm.

2. The high-performance polypropylene / cyclic olefin copolymer composite material according to claim 1, characterized in that, The polypropylene resin is homopolymer polypropylene with a melt flow rate of 0.2~20.0 g / 10min.

3. The high-performance polypropylene / cyclic olefin copolymer composite material according to claim 1, characterized in that, The cyclic olefin copolymer is a copolymer of ethylene and norbornene, with a melt flow rate of 0.5~70 g / 10min.

4. The high-performance polypropylene / cyclic olefin copolymer composite material according to claim 1, characterized in that, The high-performance polypropylene / cyclic olefin copolymer composite has a heat distortion temperature of 90~150 ℃, a tensile strength of 32.8~37.8 MPa, an elongation at break of 80~265%, and a notched impact strength of 4.1~5.1 KJ / m. 2 .

5. A method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material according to any one of claims 1 to 4, characterized in that: High-performance polypropylene / cyclic olefin copolymer composite materials are obtained by blending polypropylene resin, cyclic olefin copolymer and propylene-based elastomer, followed by melt extrusion granulation and compression molding.

6. The method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material according to claim 5, characterized in that, Before blending, the polypropylene resin and the cyclic olefin copolymer were dried separately in a vacuum oven. The polypropylene resin was dried at 60-70 °C for 1-2 h, and the cyclic olefin copolymer was dried at 80-100 °C for 3-5 h.

7. The method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material according to claim 6, characterized in that, The blending time is 10~20 min, and the melt extrusion granulation temperature is 230~260 ℃.

8. The method for preparing a high-performance polypropylene / cyclic olefin copolymer composite material according to claim 7, characterized in that, The molding process is carried out using a flat vulcanizing machine with a temperature of 240~260 ℃.

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