Polyolefin composite material and preparation method and application thereof

Abstract

The present application relates to the technical field of high polymer material modification, in particular to a polyolefin composite material and a preparation method and application thereof.The present application provides a polyolefin composite material, which comprises the following components in parts by weight: 20-30 parts of ethylene-vinyl acetate copolymer, 4-16 parts of cyclic olefin copolymer, 14-26 parts of styrene-ethylene-butylene-styrene block copolymer, 1-10 parts of a compatilizer, 34-46 parts of a flame retardant, 1-3 parts of a co-crosslinking agent, and 0-3 parts of other additives; wherein the mass content of vinyl acetate in the ethylene-vinyl acetate copolymer is greater than or equal to 30%. The polyolefin composite material has the advantages of low cost, excellent resistance to organic solvents, salt water and softness, and solves the problems of existing silica gel materials in the preparation of new energy automobile cables.

Description

Technical Field

[0001] This application relates to the field of polymer material modification technology, and in particular to a polyolefin composite material, its preparation method and application. Background Technology

[0002] With the rapid development of the new energy vehicle industry, automotive electrical systems are becoming increasingly complex, placing ever higher demands on the performance of automotive cables. The outer layer material of these cables not only needs to possess excellent electrical insulation and flame retardancy, but also requires good flexibility, resistance to organic solvents, and resistance to salt water (such as electrolytes). Specifically, during operation, the outer layer material of cables in new energy vehicles is prone to cracking when it comes into contact with organic solvents. Furthermore, the cables may come into contact with electrolytes, which contain salts; contact with electrolytes can lead to a deterioration in the cable's insulation performance.

[0003] Currently, silicone materials are widely used in the industry to manufacture cables for new energy vehicles. For example, Chinese patent application CN117497243A utilizes high-temperature resistant silicone rubber polymer materials to prepare a liquid-cooled flexible cable. This cable, thanks to the properties of silicone, exhibits excellent flexibility and high-temperature resistance, preventing cracking during long-term use and effectively ensuring the safety of driving new energy vehicles. However, silicone materials have drawbacks such as high cost and complex processing techniques.

[0004] Therefore, there is an urgent need to develop a cable material that can control costs while also possessing good resistance to organic solvents, salt water, and flexibility to meet the application requirements of cables for new energy vehicles. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing silicone materials for preparing new energy vehicle cables, which cannot simultaneously achieve low cost, resistance to organic solvents, salt water resistance and flexibility, and to provide a polyolefin composite material.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned polyolefin composite material.

[0007] Another object of the present invention is to provide the application of the above-mentioned polyolefin composite material in the manufacture of cables.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] This invention protects a polyolefin composite material comprising the following components in parts by weight: 20-30 parts of ethylene-vinyl acetate copolymer (EVA), 4-16 parts of cyclic olefin polymer, 14-26 parts of styrene-ethylene-butene-styrene block copolymer, 1-10 parts of compatibilizer, 34-46 parts of flame retardant, 1-3 parts of crosslinking agent, and 0-3 parts of other additives.

[0010] Wherein, the mass content of vinyl acetate in the ethylene-vinyl acetate copolymer is ≥30%.

[0011] This invention uses ethylene-vinyl acetate copolymer as the main resin. Compared with traditional silicone materials, ethylene-vinyl acetate copolymer has significant advantages such as low cost and simple processing technology.

[0012] To ensure that the polyolefin composite material meets basic flame retardant properties, a flame retardant is added to this invention. However, adding a flame retardant to the ethylene-vinyl acetate copolymer will degrade the material's resistance to organic solvents and its insulation properties after immersion in salt water, as well as cause the material to have excessively high hardness.

[0013] The inventors of this invention have discovered that adding a styrene-ethylene-butene-styrene block copolymer can effectively reduce the hardness of the material without deteriorating the organic solvent and salt water resistance of the polyolefin composite. Furthermore, controlling the VA (vinyl acetate) content in EVA within a specific range not only effectively reduces the material's hardness but also significantly improves its organic solvent resistance. Controlling the VA content in EVA also helps maintain the material's insulation properties after salt water immersion.

[0014] This invention further incorporates a cyclic olefin polymer, utilizing its barrier properties to improve the material's resistance to salt water immersion, thus maintaining good insulation performance after salt water immersion. However, the amount of cyclic olefin polymer used should not be excessive, otherwise it will degrade the material's resistance to organic solvents and lead to excessively high hardness.

[0015] In this invention, ethylene-vinyl acetate copolymer is used as the base resin, and its content is at least 15 wt% of the polyolefin composite material; preferably, the content of ethylene-vinyl acetate copolymer is 20-28 wt% of the polyolefin composite material.

[0016] In this invention, the amount of ethylene-vinyl acetate copolymer used can be 20, 22, 25, 27, or 30 parts by weight; the amount of cyclic olefin polymer used can be 5, 8, 10, 12, or 15 parts by weight; the amount of styrene-ethylene-butene-styrene block copolymer used can be 15, 18, 20, or 25 parts by weight; the amount of compatibilizer used can be 1, 2.5, 5, 7.5, or 10 parts by weight; the amount of flame retardant used can be 35, 40, or 45 parts by weight; the amount of crosslinking agent used can be 1, 2, or 3 parts by weight; and the amount of other additives used can be 0, 1, 1.5, 2, or 3 parts by weight.

[0017] Furthermore, the melt flow rate of the ethylene-vinyl acetate copolymer measured at 190 °C and 2.16 kg was 3~28 g / 10 min.

[0018] Preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 40% to 80% by mass.

[0019] In this invention, the mass content of vinyl acetate in the ethylene-vinyl acetate copolymer can be 40%, 50%, 60%, 70%, or 80%.

[0020] More preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 50-70% by mass.

[0021] By controlling the mass content of vinyl acetate in the ethylene-vinyl acetate copolymer within this range, the resulting polyolefin composite material exhibits better flexibility and resistance to organic solvents.

[0022] Furthermore, the melt flow rate of the cyclic olefin polymer measured at 230 °C and 2.16 kg is 0.5~25 g / 10 min, specifically 0.5, 1.5, 3, 5, 6, 9, 12, 15, 20, and 25 g / 10 min.

[0023] The test standard for melt flow rate of cyclic olefin polymers can be ASTM D-1238-2010.

[0024] Furthermore, the cyclic olefin polymer is a cyclic olefin homopolymer and / or a cyclic olefin copolymer.

[0025] Preferably, the cyclic olefin polymer accounts for 3 to 16 wt% of the polyolefin composite material.

[0026] Furthermore, the cyclic olefin copolymer is a copolymer of ethylene and cyclic olefin monomers.

[0027] Furthermore, the cyclic olefin monomer is one of norbornene or tetracyclododecene.

[0028] Preferably, the cyclic olefin monomer is tetracyclododecene.

[0029] The polyolefin composite material prepared by using tetracyclododecene has better flexibility.

[0030] Furthermore, the Shore A hardness of the styrene-ethylene-butene-styrene block copolymer is ≤70 A. The Shore A hardness can be measured according to the test standard ISO 7619-1:2010, with the following test conditions: the sample is 50 mm long and 50 mm wide, 6 mm thick, and the spring test force is held for 15 s.

[0031] Preferably, the Shore A hardness of the styrene-ethylene-butene-styrene block copolymer is 63~65 A.

[0032] By controlling the Shore A hardness of the styrene-ethylene-butene-styrene block copolymer within this range, the resulting polyolefin composite material exhibits better resistance to organic solvents.

[0033] Furthermore, the melt flow rate of the styrene-ethylene-butene-styrene block copolymer measured at 200 °C and 5 kg is 0.5~25 g / 10 min, specifically 0.5, 1.5, 3, 5, 6, 9, 12, 15, 20, 25 g / 10 min.

[0034] The test standard for the melt flow rate of styrene-ethylene-butene-styrene block copolymers can be ASTM D-1238-2010.

[0035] Furthermore, the styrene content of the styrene-ethylene-butene-styrene block copolymer is 10% to 40% by mass, and the styrene content is determined by infrared spectroscopy and nuclear magnetic resonance spectroscopy.

[0036] Preferably, the styrene-ethylene-butene-styrene block copolymer accounts for 12-27 wt% of the polyolefin composite material.

[0037] Furthermore, the compatibilizer is a maleic anhydride-based compatibilizer.

[0038] Furthermore, the maleic anhydride grafting rate of the maleic anhydride compatibilizer is 0.5%~2%, and the grafting rate is measured by infrared spectroscopy.

[0039] Furthermore, the maleic anhydride compatibilizer includes one or both of polyethylene-grafted maleic anhydride and SEBS-grafted maleic anhydride.

[0040] Furthermore, the flame retardant is a hydroxide flame retardant.

[0041] Furthermore, the flame retardant is a metal hydroxide flame retardant.

[0042] Preferably, the metal hydroxide flame retardant includes one or both of magnesium hydroxide and aluminum hydroxide.

[0043] Preferably, the particle size D of the flame retardant 50 The range is 0.8-5 μm, specifically 0.8, 1, 1.5, 2, 4, and 5 μm.

[0044] In this invention, the particle size D of the flame retardant 50 It can be measured by microscopy.

[0045] Furthermore, the co-crosslinking agent includes one or more of triallyl isocyanurate (TAIC), trimethylolpropane triacrylate (TMPTA), and trimethylolpropane trimethacrylate (TMPTMA).

[0046] Furthermore, the other additives include antioxidants and / or colorants.

[0047] Furthermore, the antioxidant includes one or more of the following: hindered phenolic antioxidants, hindered amine antioxidants, phosphite antioxidants, diphenylamine antioxidants, and thioether antioxidants.

[0048] Furthermore, the colorant is carbon black.

[0049] This invention protects a method for preparing the above-mentioned polyolefin composite material, comprising the following steps:

[0050] The components are mixed evenly to obtain a mixture, which is then subjected to intensive mixing, followed by melt extrusion and granulation to obtain a polyolefin composite material.

[0051] Furthermore, the mixing temperature is 150~200 ℃.

[0052] Furthermore, the temperature of the melt extrusion is 135~175 ℃; the screw speed of the extruder for the melt extrusion is 50~500 rpm, and the length-to-diameter ratio of the screw is 48~75:1.

[0053] This invention protects the use of the above-mentioned polyolefin composite material in the manufacture of cables.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] This invention provides a polyolefin composite material that can replace current silicone materials as cable materials, and has low cost, good resistance to organic solvents and salt water immersion, and flexibility. Detailed Implementation

[0056] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0057] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0058] Ethylene-vinyl acetate copolymer 1# (EVA-40): ELVAX 40L-03, VA content is 40%, produced by DuPont;

[0059] Ethylene-vinyl acetate copolymer 2# (EVA-50): LEVAPREN® 500, VA content 50%, produced by Lanxess, Germany;

[0060] Ethylene-vinyl acetate copolymer 3# (EVA-70): EVA700XL, VA content is 70%, produced by Lanxess, Germany;

[0061] Ethylene-vinyl acetate copolymer 4# (EVA-28): EVA 00328, VA content 28%, produced by ExxonMobil;

[0062] Compatibilizers: PE-g-MAH, MC218, produced by Nengzhiguang;

[0063] Cyclic olefin polymer 1#: Ethylene-norbornene copolymer, Topas@ 9506F-500, melt index 6 g / 10 min (230 ℃, 2.16 kg), produced by Polyplastics, Japan;

[0064] Cyclic olefin polymer 2#: ethylene-tetracyclododecene copolymer, APL5014CL(04), melt index 1.5 g / 10min (230 ℃, 2.16 kg), produced by Mitsui Chemicals;

[0065] Cyclic olefin polymer 3#: ethylene-norbornene copolymer, Topas@ 5013F-04, melt index 9 g / 10 min (230 ℃, 2.16 kg), produced by Polyplastics, Japan;

[0066] Polyethylene: LLDPE, LLDPE EXCEED 3158CB, produced by ExxonMobil;

[0067] SEBS1#: Styrene-ethylene-butene-styrene block copolymer, G1701, styrene content 37wt%, melt index 1 g / 10 min (200 ℃, 5 kg), Shore A hardness 64 A, produced by Kraton Polymers, USA.

[0068] SEBS2#: Styrene-ethylene-butene-styrene block copolymer, G1657, styrene content 13wt%, melt index 8 g / 10 min (200 ℃, 5 kg), Shore A hardness 47 A, produced by Kraton Polymers, USA.

[0069] Other toughening agents: POE elastomer, POE 58750, produced by Dow Chemical;

[0070] Flame retardant #1: Magnesium hydroxide, H-5, produced by Qiu Bo, USA;

[0071] Flame retardant #2: Aluminum hydroxide, OL-104LEO, manufactured by Qiu Bo, USA;

[0072] Crosslinking agent: triallyl isocyanurate, commercially available;

[0073] Other additives: Antioxidant 1010, commercially available.

[0074] The polyolefin composite materials of the various embodiments and comparative examples of the present invention were prepared by the following process:

[0075] The components are mixed evenly to obtain a mixture. The mixture is then fed into an internal mixer and, after internal mixing, extruded and granulated using a two-stage single-screw extruder to obtain the polyolefin composite material. The internal mixer is set to a temperature of 150~200℃, and the single-screw extruder is set to a temperature of 135~175℃ in each zone.

[0076] Examples 1-11

[0077] Examples 1-11 provide a series of polyolefin composite materials, the weight parts of each component in the formulation are shown in Table 1.

[0078] Table 1 Formulations of Examples 1-11

[0079]

[0080] Comparative Examples 1-6

[0081] This comparative example provides a series of polyolefin composite materials, the weight parts of each component in the formulation are shown in Table 2.

[0082] Table 2 Comparative Examples 1-6 Formulations

[0083]

[0084] Performance testing of polyolefin composites

[0085] (1) Test method

[0086] Organic solvent resistance: The polyolefin composite materials obtained in the various examples and comparative examples were extruded into wires using an extrusion machine, with a conductor cross-sectional area of ​​10 mm². 2 The wire has an outer diameter of 6.5 mm and is subjected to cross-linking treatment by irradiation at a dose of 15 Mrad. Toluene resistance is tested according to standard ISO 19642-2023: the initial volume V0 of the wire is tested and recorded. After the wire is completely immersed in toluene for 12 hours, it is removed and allowed to stand until the toluene has completely evaporated. The expanded volume V1 is then tested and recorded. The volume expansion rate is calculated using the formula V1 / V0*100%, and the wire is observed to see if it cracks during the immersion process. If cracking occurs during the immersion stage, the volume expansion rate will not be tested again, and the wire will be directly judged as "not meeting the organic solvent resistance standard".

[0087] Volume resistivity: The polyolefin composite materials obtained in each example and comparative example were pressed into sheets at 180°C for 10 min on a flat vulcanizing machine at a pressure of 15 MPa, forming samples with a length and width of 100 mm * 100 mm and a thickness of 1 mm. The volume resistivity of the samples was first tested at room temperature at a voltage of 1000 V. After the samples were soaked in 70 ℃ salt water for 24 h, the volume resistivity was tested again at a voltage of 1000 V. The order of magnitude of the decrease in volume resistivity after soaking in salt water was calculated. The volume resistivity test was performed in accordance with the standard IEC62631-2024.

[0088] Hardness (Shore A): The polyolefin composite materials obtained in each example and comparative example were pressed into sheets at 180 °C for 10 min on a flat vulcanizing machine with a pressure of 15 MPa, forming a sample with a length and width of 50 mm * 50 mm and a thickness of 6 mm. The test was carried out in accordance with the standard ISO7619-1:2010, and the spring test force holding time was 15 s.

[0089] (2) Experimental results

[0090] Table 3 Performance test results of each embodiment and comparative example

[0091]

[0092] As shown in Table 3, the polyolefin composite materials prepared in Examples 1 to 11 of this invention all have the characteristics of softness, salt water resistance, and organic solvent resistance; specifically, the Shore A hardness is ≤75 A; after soaking in salt water, the volume resistivity decreases by ≤1 order of magnitude; after soaking in toluene, no cracking occurs, and the volume expansion rate is ≤115%, among which Example 1 has the best overall performance.

[0093] Comparative Example 1, lacking the addition of cyclic olefin polymers, experienced a three-order-of-magnitude decrease in volume resistivity after immersion in 70°C brine, severely impacting its insulation performance. Furthermore, its excessive volume expansion after immersion in toluene negatively affected its resistance to organic solvents. Comparative Example 2, with its high cyclic olefin polymer content, resulted in excessive material hardness and insufficient resistance to organic solvents, leading to cracking of the composite material. Comparative Example 3, using a low-VA-content ethylene-vinyl acetate copolymer, also resulted in excessive material hardness and insufficient resistance to organic solvents, causing cracking of the composite material. Comparative Example 4, using polyethylene instead of cyclic olefin polymers, saw a two-order-of-magnitude decrease in volume resistivity after brine immersion, affecting its insulation performance. Comparative Example 5, omitting cyclic olefin polymers and replacing them with an equal amount of ethylene-vinyl acetate copolymer, experienced severe deterioration in volume resistivity after brine immersion, decreasing by three orders of magnitude, resulting in significantly worsened insulation performance. Comparative Example 6, using POE elastomer instead of SEBS, saw a two-order-of-magnitude decrease in volume resistivity after brine immersion, affecting its insulation performance and exhibiting insufficient resistance to organic solvents, leading to cracking after immersion in toluene.

[0094] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A polyolefin composite material, characterized in that, It includes the following components in parts by weight: 20-30 parts of ethylene-vinyl acetate copolymer, 4-16 parts of cyclic olefin copolymer, 14-26 parts of styrene-ethylene-butene-styrene block copolymer, 1-10 parts of compatibilizer, 34-46 parts of flame retardant, 1-3 parts of crosslinking agent, and 0-3 parts of other additives. The vinyl acetate content in the ethylene-vinyl acetate copolymer is 40% to 80% by mass.

2. The polyolefin composite material according to claim 1, characterized in that, The melt flow rate of the cyclic olefin copolymer, measured at 230 °C and 2.16 kg, was 0.5~25 g / 10 min.

3. The polyolefin composite material according to claim 1, characterized in that, The cyclic olefin copolymer is a copolymer of ethylene and cyclic olefin monomers.

4. The polyolefin composite material according to claim 1, characterized in that, The melt flow rate of the styrene-ethylene-butene-styrene block copolymer was measured at 200 °C and 5 kg as 0.5~25 g / 10 min.

5. The polyolefin composite material according to claim 1, characterized in that, The flame retardant is a hydroxide flame retardant.

6. The polyolefin composite material according to claim 1, characterized in that, The compatibilizer is a maleic anhydride-based compatibilizer.

7. The polyolefin composite material according to claim 1, characterized in that, The co-crosslinking agent includes one or more of triallyl isocyanurate, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

8. A method for preparing the polyolefin composite material according to any one of claims 1 to 7, characterized in that, Includes the following steps: The components are mixed evenly to obtain a mixture, which is then subjected to intensive mixing, followed by melt extrusion and granulation to obtain the polyolefin composite material.

9. The use of the polyolefin composite material according to any one of claims 1 to 7 in the preparation of cables.

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