A modified ethylene propylene diene rubber composite material and a preparation method thereof

Abstract

This invention belongs to the field of rubber modification technology, specifically relating to a modified ethylene propylene diene monomer (EPDM) rubber composite material and its preparation method. The modified EPDM rubber composite material provided by this invention comprises, by weight, the following raw materials: 100 parts of EPDM rubber base material, 3-8 parts of activator, 0.5-2.5 parts of antioxidant, 5-15 parts of special resin, 5-15 parts of reactive phosphazene derivative, 5-15 parts of softener, 10-25 parts of reinforcing agent, 10-30 parts of fiber, 3-10 parts of foaming agent, 0.5-3 parts of accelerator, and 2-4.5 parts of vulcanizing agent; the total mass ratio of the accelerator and vulcanizing agent to the foaming agent is 4-6:4-6. The modified EPDM rubber composite material provided by this invention has low density, ablation resistance, and good mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of rubber modification technology, specifically relating to a modified EPDM rubber composite material and its preparation method. Background Technology

[0002] With the rapid development of the modern aerospace industry, higher demands are being placed on spacecraft engines for lightweight design, overload capacity, and ablation resistance. Currently, spacecraft engine materials include carbon-carbon composites, carbon-phenol composites, or carbon-ceramic composites. These materials possess high strength, high temperature resistance, wear resistance, and impact resistance; however, they also have the drawback of high density, leading to reduced payload. Existing technologies use rubber-based composite materials as the main material for spacecraft engines, but currently disclosed rubber-based composite materials have a density greater than 1.05 g / cm³. 3 The linear ablation rate is 0.10~0.150 mm / s. With the linear ablation rate remaining essentially constant, the density cannot be reduced to 0.80 g / cm³. 3 the following.

[0003] Furthermore, with the rapid development of new energy sources, higher requirements are being placed on the protection of electrical components and battery packs. Currently, EPDM rubber materials filled with halogen-free flame retardants are used to protect electrical components and battery packs. However, the high filler content of traditional halogen-free flame retardants leads to a decrease in the elasticity of EPDM rubber and makes it difficult to process, while the low filler content of traditional halogen-free flame retardants results in a density of EPDM rubber greater than 1.05 g / cm³. 3 The linear ablation rate is 0.18~0.25 mm / s, making it impossible to obtain a density lower than 0.8 g / cm³. 3 Ethylene propylene diene monomer (EPDM) rubber composites that maintain excellent mechanical and ablation properties. Summary of the Invention

[0004] The purpose of this invention is to provide a modified EPDM rubber composite material and its preparation method. The modified EPDM rubber composite material provided by this invention has low density, ablation resistance, and good mechanical properties.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A modified ethylene propylene diene monomer (EPDM) rubber composite material, comprising the following raw materials in parts by mass: 100 parts of EPDM rubber base material, 3-8 parts of activator, 0.5-2.5 parts of antioxidant, 5-15 parts of special resin, 5-15 parts of reactive phosphazene derivative, 5-15 parts of softener, 10-25 parts of reinforcing agent, 10-30 parts of fiber, 3-10 parts of foaming agent, 0.5-3 parts of accelerator and 2-4.5 parts of vulcanizing agent; The special resin includes an inorganic hybrid phenolic resin; the reactive phosphazene derivative is a cyclic phosphazene; the total mass ratio of the accelerator and vulcanizing agent to the foaming agent is 4~6:4~6.

[0006] Preferably, the EPDM rubber substrate is copolymerized from ethylene, propylene and a third monomer, wherein the third monomer includes ethylene norbornene, 1,4-hexadiene or dicyclopentadiene, and the mass of the third monomer is 3 to 8% of the mass of the EPDM rubber substrate.

[0007] Preferably, the inorganic hybrid phenolic resin contains inorganic elements including silicon, boron, or barium, and the mass content of the inorganic elements in the inorganic hybrid phenolic resin is 15-30%; the inorganic hybrid phenolic resin includes one or more of hybrid silicon phenolic resin, hybrid boron silicon phenolic resin, or hybrid barium phenolic resin.

[0008] Preferably, the reactive phosphazene derivative comprises a six-membered cyclic phosphazene, wherein the substituents of the six-membered cyclic phosphazene include one or more of aniline, phenoxy, and allylamino groups.

[0009] Preferably, the activator includes one or more of zinc oxide, magnesium oxide, and stearic acid; the antioxidant includes one or more of antioxidant 4010NA, antioxidant RD, antioxidant MB, and antioxidant 445; the softener includes one or more of paraffin oil, naphthenic oil, and aromatic oil; the reinforcing agent includes precipitated silica and / or fumed silica; the fiber includes aramid fiber; the foaming agent includes foaming agent OBSH and / or foaming agent AC; the accelerator includes one or more of accelerator CZ, accelerator TMTD, accelerator HA-8, accelerator TAIC, accelerator TRA, accelerator TE, accelerator BZ, and accelerator DM; and the vulcanizing agent includes peroxides and sulfides.

[0010] Preferably, the peroxide in the vulcanizing agent includes dicumyl peroxide, the sulfide in the vulcanizing agent includes sulfur-80, and the mass ratio of the peroxide to the sulfide is 1.5~3.5:0.5~1; the aramid fiber includes 3mm aramid fiber and / or 6mm aramid fiber.

[0011] This invention provides a method for preparing the modified EPDM rubber composite material described above, comprising the following steps: The EPDM rubber substrate is plasticized to obtain raw rubber; The raw rubber, activator, antioxidant, reinforcing agent, softener, fiber, special resin, reactive phosphazene derivative, accelerator, vulcanizing agent and foaming agent are mixed and compounded to obtain a compound rubber. The compounded rubber is successively kneaded and cold-pressed to obtain a rubber blank; The rubber preform is vulcanized to obtain the modified EPDM rubber composite material.

[0012] Preferably, the mixing process includes: first mixing the raw rubber, activator, antioxidant, reinforcing agent, and softener to obtain a first mixed rubber; second mixing the first mixed rubber with fibers to obtain a second mixed rubber; third mixing the second mixed rubber, a special resin, and a reactive phosphazene derivative to obtain a third mixed rubber; and fourth mixing the third mixed rubber, an accelerator, a vulcanizing agent, and a foaming agent to obtain the mixed rubber; wherein the temperature of the first mixing is 40-60°C and the time is 4-6 min; the temperature of the second mixing is 40-60°C and the time is 10-30 min; the temperature of the third mixing is 40-60°C and the time is 4-6 min; and the temperature of the fourth mixing is 20-60°C and the time is 3-10 min.

[0013] Preferably, the vulcanization temperature is 150~170℃, the pressure is 12~18MPa, and the time is 15~25min.

[0014] This invention provides the application of the modified EPDM rubber composite material described in the above technical solution or the modified EPDM rubber composite material prepared by the preparation method described in the above technical solution in aerospace engines or new energy battery packs.

[0015] Beneficial Effects: The modified EPDM rubber composite material provided by this invention has the advantages of low density, ablation resistance, and excellent mechanical properties. This invention uses EPDM rubber as the base material, which reduces the basic density and thermal conductivity, improving aging resistance and physical and mechanical properties. The addition of special resins and reactive phosphazene derivatives enhances the interfacial strength between materials, thereby improving physical and mechanical properties and ablation resistance. The special resins can bond with the fiber interface and are introduced into the EPDM rubber crosslinking network, synergistically generating a three-dimensional spatial structure. The reactive phosphazene derivatives can prevent further combustion of combustible components in the EPDM rubber base material, reducing the ablation rate. Furthermore, the special resins and reactive phosphazene derivatives form a carbon ablation layer at extreme high temperatures, improving ablation resistance. The addition of fibers improves processing performance and ablation resistance. This invention reduces the density of the modified EPDM rubber composite material by limiting the total mass ratio of vulcanizing agent and accelerator to foaming agent.

[0016] Furthermore, this invention reduces fiber orientation by limiting the use of fibers of different lengths, thereby improving physical and mechanical properties; and adjusts the ablation resistance by adjusting the total amount of fibers used and the fiber length, thereby achieving an optimal balance between physical and mechanical properties and ablation resistance.

[0017] Furthermore, the modified EPDM rubber composite material of this invention also possesses advantages such as aging resistance, insulation, low thermal conductivity, and cold resistance. The modified EPDM rubber composite material prepared by this invention is suitable for applications related to engine insulation layers and external thermal insulation layers for new energy battery packs.

[0018] The preparation method provided by this invention is simple, easy to operate, and has high production efficiency. Detailed Implementation

[0019] This invention provides a modified ethylene propylene diene monomer (EPDM) rubber composite material, comprising the following raw materials in parts by weight: 100 parts of EPDM rubber base material, 3-8 parts of activator, 0.5-2.5 parts of antioxidant, 5-15 parts of special resin, 5-15 parts of reactive phosphazene derivative, 5-15 parts of softener, 10-25 parts of reinforcing agent, 10-30 parts of fiber, 3-10 parts of foaming agent, 0.5-3 parts of accelerator and 2-4.5 parts of vulcanizing agent; The special resin includes an inorganic hybrid phenolic resin; the reactive phosphazene derivative is a cyclic phosphazene; the total mass ratio of the accelerator and vulcanizing agent to the foaming agent is 4~6:4~6.

[0020] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0021] The modified EPDM rubber composite material of the present invention comprises, by weight, 100 parts of EPDM rubber substrate. In one embodiment of the present invention, the EPDM rubber substrate is copolymerized from ethylene, propylene, and a third monomer, wherein the third monomer includes ethylene-ide norbornene (ENB), 1,4-hexadiene (HD), or dicyclopentadiene (DCPD), and the mass of the third monomer is 3-8% of the mass of the EPDM rubber substrate. In the present invention, the EPDM rubber substrate includes ENB-type EPDM, HD-type EPDM, and DCPD-type EPDM. The ENB-type EPDM is purchased from Jilin Petrochemical Company of China National Petroleum Corporation, model J-4045; under the conditions of preheating at 100°C for 1 min and rotor operation for 4 min (ML(1+4)100°C), its Mooney viscosity is 45 and its density is 0.863 g / cm³. 3 The content of the third monomer, ENB, is 7.5 wt%; the DCPD type EPDM rubber was purchased from Keltan® 3040D, with a Mooney viscosity of 40 at 125°C and a density of 0.862 g / cm³. 3The content of the third monomer, DCPD, is 3.1 wt%; the HD-type EPDM rubber was purchased from Dow Chemical Company, model NORDEL™ 4760H, with a Mooney viscosity of 45 at 125°C and a density of 0.865 g / cm³. 3 The content of the third monomer HD is 6.5 wt%.

[0022] The present invention uses EPDM rubber as a base material, which can reduce the base density and thermal conductivity, and improve the aging resistance and physical and mechanical properties.

[0023] The modified EPDM rubber composite material of the present invention comprises, by weight, 3 to 8 parts of an activator. In one embodiment of the present invention, the activator comprises 3 to 8 parts by weight, specifically 3, 5, or 8 parts; the activator includes one or more of zinc oxide, magnesium oxide, and stearic acid. In the present invention, the activator is a compound of two components, specifically 3 parts zinc oxide and 2 parts stearic acid, 2 parts magnesium oxide and 1 part stearic acid, or 5 parts zinc oxide and 3 parts stearic acid.

[0024] The activator, accelerator, and sulfur of this invention constitute a highly efficient catalytic-crosslinking system. This system can enhance the vulcanization rate and degree of sulfur vulcanization of EPDM rubber matrix molecules, thereby improving the tensile strength and mechanical properties of the modified EPDM rubber composite material at a given elongation stress.

[0025] The modified EPDM rubber composite material of the present invention comprises, by weight, 0.5 to 2.5 parts of antioxidant. In one embodiment of the present invention, the antioxidant is 0.5 to 2.5 parts by weight, specifically 0.5 parts, 0.8 parts, 1 part, 1.5 parts, or 2.5 parts; the antioxidant includes one or more of antioxidant 4010NA, antioxidant RD, antioxidant MB, and antioxidant 445. In the present invention, the antioxidant is a combination of one or two, specifically 1 part of antioxidant 4010NA and 0.5 parts of antioxidant RD, 0.8 parts of antioxidant MB, 1.5 parts of antioxidant 445 and 1 part of antioxidant RD.

[0026] The antioxidant of this invention can delay or inhibit the aging of EPDM rubber substrates caused by various environmental factors during use through chemical or physical means, thereby significantly extending the service life of modified EPDM rubber composite materials.

[0027] The modified EPDM rubber composite material of the present invention comprises, by weight, 5-15 parts of a special resin; the special resin includes an inorganic hybrid phenolic resin. In one embodiment of the present invention, the special resin comprises 5-15 parts by weight, specifically 5 parts, 10 parts, or 15 parts; the inorganic hybrid phenolic resin contains silicon, boron, or barium as inorganic elements, and the inorganic element content in the inorganic hybrid phenolic resin is 15-30% by weight; the inorganic hybrid phenolic resin includes one or more of hybrid silicon phenolic resin, hybrid boron silicon phenolic resin, or hybrid barium phenolic resin. In the present invention, the special resin may specifically be 10 parts of hybrid silicon phenolic resin, 5 parts of hybrid boron silicon phenolic resin, or 15 parts of a mixture of hybrid silicon phenolic resin and hybrid boron silicon phenolic resin in a 1:1 weight ratio. The hybrid boron-silicon-phenolic resin of the present invention is boron-phenolic resin grafted with allyl silane, the hybrid silicon-phenolic resin is phenolic resin grafted with allyl silane, and the hybrid barium-phenolic resin is phenolic resin grafted with phenolic resin.

[0028] The inorganic hybrid phenolic resin is composed of inorganic elements covalently bonded to phenolic resin, and also possesses the function of thermal vulcanization crosslinking with EPDM rubber. The residual hydroxyl groups in the special resin of this invention can bond well with the fiber interface; furthermore, the thermal vulcanization groups can introduce phenolic segments into the EPDM rubber crosslinking network, synergistically generating a three-dimensional spatial structure, forming a solid carbon ablation layer at extreme high temperatures, and improving the material's resistance to ablation and erosion.

[0029] The modified EPDM rubber composite material of the present invention comprises, by mass parts, 5-15 parts of a reactive phosphazene derivative; the reactive phosphazene derivative is a cyclic phosphazene. As one embodiment of the present invention, the reactive phosphazene derivative comprises 5-15 parts by mass, specifically 5 parts, 10 parts, or 15 parts; the reactive phosphazene derivative includes a six-membered cyclic phosphazene, and the substituents of the six-membered cyclic phosphazene include one or more of aniline, phenoxy, and allylamino groups. The reactive phosphazene derivative used in the present invention includes RSC-11 or RSC-12, wherein RSC-11 is a six-membered cyclic phosphazene substituted with aniline and allylamino groups, and RSC-12 is a six-membered cyclic phosphazene substituted with phenoxy and allylamino groups. In this invention, the reactive phosphazene derivative can specifically be 10 parts of RSC-11, 5 parts of RSC-12, or 15 parts of a mixture of RSC-11 and RSC-12 in a mass ratio of 1:1.

[0030] The reactive phosphazene derivative of this invention is a six-membered cyclic phosphazene with a heat-resistant benzene ring bonded to the phosphorus element and containing double bonds capable of co-vulcanizing with rubber. This reactive phosphazene derivative can thermally release phosphorus and nitrogen inert gases under high-temperature conditions, preventing further combustion of flammable components in the EPDM rubber substrate and reducing the ablation rate. Furthermore, the cyclic phosphazene also has the ability to promote the rapid formation of a hard carbon layer in the ablation layer, improving the ablation and erosion resistance of the modified EPDM rubber composite material, resulting in superior ablation and erosion resistance.

[0031] The modified EPDM rubber composite material of the present invention comprises, by weight, 5-15 parts of a softener. In one embodiment of the present invention, the softener comprises 5-15 parts by weight, specifically 5 parts, 8 parts, 10 parts, or 15 parts; the softener includes one or more of paraffin oil, naphthenic oil, and aromatic oil. In the present invention, the softener may specifically be 8 parts of paraffin oil, 5 parts of naphthenic oil, and 15 parts of aromatic oil.

[0032] The softener of this invention can improve the processing performance and temperature resistance of modified EPDM rubber composites. When the softener is paraffin oil, it can improve the processing performance of the modified EPDM rubber composites while having low pollution and good high-temperature resistance. When the softener is aromatic oil, it is added and absorbed quickly during the mixing process, which can improve the processing performance of the modified EPDM rubber composites. When the softener is naphthenic oil, it can simultaneously improve the processing performance and the dispersibility of the material.

[0033] The modified EPDM rubber composite material of the present invention comprises, by weight, 10-25 parts of reinforcing agent. In one embodiment of the present invention, the reinforcing agent comprises 10-25 parts by weight, specifically 10 parts, 15 parts, or 25 parts; the reinforcing agent comprises precipitated silica and / or fumed silica; when the reinforcing agent is precipitated silica and fumed silica, the mass ratio of precipitated silica to fumed silica is 3:2. In the present invention, the reinforcing agent may be 10 parts of precipitated silica, 10 parts of fumed silica, or 10 parts of a compound mixture of precipitated silica and fumed silica in a mass ratio of 3:2.

[0034] The reinforcing agent of this invention can improve the physical and mechanical properties of EPDM rubber substrate, and also provide excellent insulation and lower thermal conductivity.

[0035] The modified EPDM rubber composite material of the present invention comprises, by weight, 10-30 parts of fiber. In one embodiment of the present invention, the fiber comprises 10-30 parts by weight, specifically 10, 20, or 30 parts; the fiber comprises aramid fiber, specifically 3mm aramid fiber and / or 6mm aramid fiber; when the fiber is 3mm aramid fiber and 6mm aramid fiber, the weight ratio of the 3mm aramid fiber to the 6mm aramid fiber is 4:6 or 6:4. In the present invention, the fiber may specifically be 10 parts of 6mm aramid fiber, 10 parts of a blend of 3mm aramid fiber and 6mm aramid fiber in a weight ratio of 4:6, or 10 parts of a blend of 3mm aramid fiber and 6mm aramid fiber in a weight ratio of 6:4.

[0036] The fibers of this invention can improve the processing performance and ablation and erosion resistance of modified EPDM rubber composites, while exhibiting low orientation. This invention reduces fiber orientation by limiting the use of fibers of different lengths, resulting in superior physical and mechanical properties. Furthermore, the ablation resistance is adjusted by controlling the total amount of fibers used and their length; combining these two adjustments achieves an optimal balance between physical and mechanical properties and ablation resistance.

[0037] The modified EPDM rubber composite material of the present invention comprises, by weight, 3 to 10 parts of a foaming agent. In one embodiment of the present invention, the foaming agent comprises 3 to 10 parts by weight, specifically 3 parts, 6 parts, or 10 parts; the foaming agent is OBSH and / or AC; when the foaming agent is OBSH and AC, the mass ratio of OBSH and AC is 1:1. In the present invention, the foaming agent may specifically be 6 parts of OBSH, 3 parts of AC, or 10 parts of a mixture of OBSH and AC in a 1:1 mass ratio.

[0038] The modified EPDM rubber composite material of the present invention comprises, by weight, 0.5 to 3 parts of accelerator. In one embodiment of the present invention, the accelerator is 0.5 to 3 parts by weight, specifically 0.5, 1, 1.5, or 3 parts; the accelerator includes one or more of accelerator CZ, accelerator TMTD, accelerator HA-8, accelerator TAIC, accelerator TRA, accelerator TE, accelerator BZ, and accelerator DM. In the present invention, the accelerator is a combination of one or two, specifically 1 part of accelerator CZ and 0.5 parts of accelerator TMTD, 0.5 parts of accelerator DM, 1.5 parts of accelerator HA-8, and 1.5 parts of accelerator TAIC.

[0039] The modified EPDM rubber composite material of the present invention comprises, by weight, 2 to 4.5 parts of vulcanizing agent. In one embodiment of the present invention, the vulcanizing agent comprises 2 to 4.5 parts by weight, specifically 0.5, 0.8, 1, 1.5, 2, 2.2, 3, 3.5, or 4.5 parts; the vulcanizing agent comprises peroxide and sulfide; the peroxide in the vulcanizing agent comprises dicumyl peroxide, and the sulfide in the vulcanizing agent comprises sulfur-80; the mass ratio of the peroxide to the sulfide is 1.5 to 3.5:0.5 to 1, specifically 2.2:0.8, 1.5:0.5, or 3.5:1. In this invention, the vulcanizing agent may specifically be 2.2 parts of dicumyl peroxide and 0.8 parts of sulfur-80, 1.5 parts of dicumyl peroxide and 0.5 parts of sulfur-80, or 3.5 parts of dicumyl peroxide and 1 part of sulfur-80.

[0040] The mass ratio of the accelerator and vulcanizing agent to the foaming agent is 4~6:4~6, specifically 4:6, 5:5, or 6:4. This invention reduces the density of the modified EPDM rubber composite material by limiting the mass ratio of the vulcanizing agent and accelerator to the foaming agent.

[0041] This invention provides a method for preparing the modified EPDM rubber composite material described above, comprising the following steps: The EPDM rubber substrate is plasticized to obtain raw rubber. The raw rubber, activator, antioxidant, reinforcing agent, softener, fiber, special resin, reactive phosphazene derivative, accelerator, vulcanizing agent and foaming agent are mixed and compounded to obtain compound rubber. The compounded rubber is successively kneaded and cold-pressed to obtain a rubber blank; The rubber preform is vulcanized to obtain the modified EPDM rubber composite material.

[0042] This invention involves plasticizing a EPDM rubber substrate to obtain raw rubber. In one embodiment, the plasticizing is performed on a two-roll mill with a roll gap of 0.3-1 mm, specifically 0.3 mm, 0.5 mm, or 1 mm. The EPDM rubber substrate is passed through the rolls by triangular wrapping and / or left-right tamping, the number of passes being 4-8 times, specifically 4, 6, or 8 times.

[0043] After obtaining the raw rubber, the present invention mixes the raw rubber, activator, antioxidant, reinforcing agent, softener, fiber, special resin, reactive phosphazene derivative, accelerator, vulcanizing agent, and foaming agent, and performs compounding to obtain a compound rubber. In one embodiment of the present invention, the compounding is carried out on a two-roll mill with a roll gap of 0.5~2mm, specifically 0.8mm, 1mm, or 2mm. The compounding specifically includes: adding the raw rubber to the two-roll mill, and after it completely covers the rolls, adding the activator, antioxidant, reinforcing agent, and softener for a first compounding to obtain a first compound rubber; performing a second compounding with the fiber to obtain a second compound rubber; performing a third compounding with the second compound rubber, special resin, and reactive phosphazene derivative to obtain a third compound rubber; and performing a fourth compounding with the third compound rubber, accelerator, vulcanizing agent, and foaming agent to obtain a fourth compound rubber. The temperature of the first compounding is 40~60°C. The first mixing temperature is 0℃, and the time is 4~6 min, specifically 4 min, 5 min, or 6 min; the second mixing temperature is 40~60℃, specifically 40℃, 50℃, or 60℃, and the time is 10~30 min, specifically 10 min, 20 min, or 30 min; the third mixing temperature is 40~60℃, specifically 40℃, 50℃, or 60℃, and the time is 4~6 min, specifically 4 min, 5 min, or 6 min; the fourth mixing temperature is 20~60℃, specifically 25℃, 40℃, or 60℃, and the time is 3~10 min, specifically 3 min, 6 min, or 10 min.

[0044] In one embodiment of the present invention, after obtaining the fourth compound rubber, the process further includes: subjecting the fourth compound rubber to triangular folding and / or left-right tamping, adjusting the roll gap of the open mill to 0.3~1mm, specifically 0.3mm, 0.5mm or 1mm, sequentially performing thin-passing and triangular folding, then adjusting the roll gap of the open mill to 2~6mm, specifically 2mm, 4mm or 6mm, sheeting, cooling, and resting to obtain the compound rubber; the number of times the triangular folding and / or left-right tamping is performed is 4~8 times; the thin-passing time is 5~15min, specifically 5min, 10min or 15min, the number of times the triangular folding is performed is 5~10 times, specifically 5 times, 8 times or 10 times; the resting time is 4~48h, specifically 4h, 24h or 48h.

[0045] After obtaining the compounded rubber, the present invention sequentially performs refining and cold pressing to obtain a rubber preform. In one embodiment of the present invention, the refining is carried out on an open mill with a roll gap of 0.3~1mm, specifically 0.3mm, 0.5mm, or 1mm, and the refining includes passing the material through a thin tube 3~8 times, specifically 3 times, 5 times, or 8 times; the cold pressing is carried out on a flat vulcanizing mill for 2~10 minutes, specifically 2 minutes, 6 minutes, or 10 minutes; the thickness of the rubber preform is 70~120% of the target thickness of the modified EPDM rubber composite material, specifically 70%, 80%, or 120%; the rubber preform is cut into samples, and the weight of the cut preform is greater than 8~15% of the theoretically calculated rubber consumption of the mold cavity, specifically 8%, 12%, or 15%.

[0046] After obtaining the rubber preform, the present invention vulcanizes the rubber preform to obtain the modified EPDM rubber composite material. In one embodiment of the present invention, the vulcanization temperature is 150~170℃, specifically 150℃, 160℃, or 170℃; the pressure is 12~18MPa, specifically 12MPa, 15MPa, or 18MPa; and the time is 15~25min, specifically 15min, 20min, or 25min.

[0047] This invention provides the application of the modified EPDM rubber composite material described in the above technical solution or the modified EPDM rubber composite material prepared by the preparation method described in the above technical solution in aerospace engines or new energy battery packs.

[0048] To further illustrate the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments thereof. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0049] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. The EPDM rubber substrate is selected from ENB type EPDM rubber, HD type EPDM rubber, or DCPD type EPDM rubber. The ENB type EPDM rubber was purchased from Jilin Petrochemical Company of China National Petroleum Corporation, model J-4045. Under the conditions of preheating the large rotor at 100℃ for 1 min and running the rotor for 4 min (ML(1+4)100℃), the Mooney viscosity is 45 and the density is 0.863 g / cm³. 3The content of the third monomer, ENB, is 7.5 wt%; the DCPD type EPDM rubber was purchased from Keltan® 3040D, with a Mooney viscosity of 40 at 125°C and a density of 0.862 g / cm³. 3 The content of the third monomer, DCPD, is 3.1 wt%; the HD-type EPDM rubber was purchased from Dow Chemical Company, model NORDEL™ 4760H, with a Mooney viscosity of 45 at 125°C and a density of 0.865 g / cm³. 3 The content of the third monomer HD is 6.5 wt%. The vulcanizing agent is mainly peroxide (DCP content ≥99%), and supplemented by sulfide (sulfur-80, sulfur content 80%, carrier EPDM rubber); the foaming agent and aramid fiber both meet industrial grade standards; by weight, the reinforcing agent is fixed at 10 parts and the aramid fiber is fixed at 10 parts.

[0050] Example 1 Each component, by mass parts, includes: EPDM rubber base material: 100 parts of ENB type EPDM rubber; activator: 3 parts of zinc oxide and 2 parts of stearic acid; antioxidant: 1 part of antioxidant 4010NA and 0.5 parts of antioxidant RD; special resin: 10 parts of hybrid silicone phenolic resin; reactive phosphazene derivative: 10 parts of RSC-11; softener: 8 parts of paraffin oil; reinforcing agent: 10 parts of precipitated silica; fiber: 10 parts of aramid fiber (3mm aramid fiber and 6mm aramid fiber in a mass ratio of 6:4); foaming agent: 6 parts of foaming agent OBSH; accelerator: 1 part of accelerator CZ and 0.5 parts of accelerator TMTD; vulcanizing agent: 2.2 parts of DCP and 0.8 parts of sulfur-80.

[0051] The preparation method of modified EPDM rubber composite material is carried out according to the following steps: (1) The weighed ENB type EPDM rubber is put into an open mill with a roller gap of 0.5mm. The triangular wrapping and left and right rubbing are alternated and the rubber is passed through the rollers a total of 6 times. The rubber is plasticized until the rubber texture is uniform and there are no obvious particles, and the raw rubber is obtained.

[0052] (2) Adjust the roller gap of the open mill to 1 mm, add the raw rubber, and after the raw rubber completely covers the roller, add the activator, antioxidant, reinforcing agent and softener in sequence, and mix at 50°C for 5 min; then add aramid fiber, control the mixing temperature to 50°C, and continue mixing for 20 min; then add special resin and reactive phosphazene derivative and mix at 50°C for 5 min; then add accelerator, vulcanizing agent and foaming agent, control the mixing temperature to 40°C, mix for 6 min, and alternate between triangular wrapping and left and right rubbing 4 times; adjust the roller gap to 0.5 mm, thin pass for 10 min, make triangular wrapping 8 times, then adjust the roller gap to 4 mm, sheet and cool to room temperature, and let stand for 24 h to obtain the compound rubber.

[0053] (3) Adjust the gap of the open mill to 0.5 mm, feed the mixed rubber through a thin pass 5 times for refining, and then feed it into a flat vulcanizing machine for cold pressing for 6 minutes to obtain a rubber blank. The thickness of the rubber blank is 70% of the target thickness of the modified EPDM rubber composite material. The rubber blank is cut into samples. The weight of the cut rubber blank is 12% more than the theoretical rubber consumption calculated by the mold cavity.

[0054] (4) Place the cut rubber blank into the mold and place it in the flat vulcanizing machine for vulcanization. Control the vulcanization temperature to 160℃, the vulcanization pressure to 15MPa, and the vulcanization time to 20min. After vulcanization, take it out and cool it to room temperature to obtain the modified EPDM rubber composite material.

[0055] Example 2 Each component, by mass parts, includes: EPDM rubber base material: 100 parts DCPD type EPDM rubber; activator: 2 parts magnesium oxide and 1 part stearic acid; antioxidant: 0.8 parts antioxidant MB; special resin: 5 parts hybrid boron-silicon-phenolic resin; reactive phosphazene derivative: 5 parts RSC-12; softener: 5 parts naphthenic oil; reinforcing agent: 10 parts fumed silica; fiber: 10 parts 6mm aramid fiber; foaming agent: 3 parts foaming agent AC; accelerator: 0.5 parts accelerator DM; vulcanizing agent: 1.5 parts DCP and 0.5 parts sulfur-80.

[0056] The preparation method of modified EPDM rubber composite material is carried out according to the following steps: (1) The weighed DCPD type EPDM rubber is put into an open mill with a roller gap of 0.3mm, and passed through the rollers in a triangular shape 4 times to plasticize until the rubber texture is uniform and there are no obvious particles, thus obtaining raw rubber.

[0057] (2) Adjust the roller gap of the open mill to 0.8 mm, add the raw rubber, and after the raw rubber completely covers the rollers, add the activator, antioxidant, reinforcing agent and softener in sequence, and mix at 50°C for 4 min; then add aramid fiber, control the mixing temperature to 40°C, and continue mixing for 10 min; then add special resin and reactive phosphazene derivative and mix at 40°C for 4 min; then add accelerator, vulcanizing agent and foaming agent, control the mixing temperature to 25°C, mix for 3 min, and make triangular wraps 4 times; adjust the roller gap to 0.3 mm, pass through thinly for 5 min, make triangular wraps 5 times, then adjust the roller gap to 2 mm, sheet out and cool to room temperature, and let stand for 4 h to obtain the compound rubber.

[0058] (3) Adjust the gap of the open mill to 0.3 mm, feed the mixed rubber through the thin pass 3 times for refining, and then feed it into the flat vulcanizing machine for cold pressing for 2 min to obtain the rubber blank. The thickness of the rubber blank is 70% of the target thickness of the modified EPDM rubber composite material. The rubber blank is cut into samples. The weight of the cut rubber blank is 8% more than the theoretical rubber consumption calculated by the mold cavity.

[0059] (4) Place the cut rubber blank into the mold and place it in the flat vulcanizing machine for vulcanization. Control the vulcanization temperature to 150℃, the vulcanization pressure to 12MPa, and the vulcanization time to 15min. After vulcanization, take it out and cool it to room temperature to obtain the modified EPDM rubber composite material.

[0060] Example 3 Each component, by mass parts, includes: EPDM rubber base material: 100 parts HD type EPDM rubber; activator: 5 parts zinc oxide and 3 parts stearic acid; antioxidant: 1.5 parts antioxidant 445 and antioxidant RD 1 part; Special resin: (hybrid silicone phenolic resin and hybrid borosilicate phenolic resin are compounded in a 1:1 mass ratio) 15 parts; Reactive phosphazene derivative: (RSC-11 and RSC-12 are compounded in a 1:1 mass ratio) 15 parts; Softener: Aromatic oil 15 parts; Reinforcing agent: (precipitated silica and fumed silica are compounded in a 3:2 mass ratio) 10 parts; Fiber: (3mm aramid fiber and 6mm aramid fiber are compounded in a 4:6 mass ratio) 10 parts; Foaming agent: (foaming agent OBSH and foaming agent AC are compounded in a 1:1 mass ratio) 10 parts; Accelerator: (accelerator HA-8 and accelerator TAIC are compounded in a 1:1 mass ratio) 3 parts; Vulcanizing agent: DCP 3.5 parts and sulfur-80 1 part.

[0061] The preparation method of modified EPDM rubber composite material is carried out according to the following steps: (1) The weighed HD type EPDM rubber is put into a two-roll mill with a roller gap of 1mm, and the rubber is pounded from side to side through the rollers 8 times. The rubber is plasticized until the rubber texture is uniform and there are no obvious particles, thus obtaining raw rubber.

[0062] (2) Adjust the roller gap of the open mill to 2 mm, add the raw rubber, and after the raw rubber completely covers the rollers, add the activator, antioxidant, reinforcing agent and softener in sequence, and mix at 50°C for 6 min; then add aramid fiber, control the mixing temperature to 60°C, and continue mixing for 30 min; then add special resin and reactive phosphazene derivative and mix at 60°C for 6 min; then add accelerator, vulcanizing agent and foaming agent, control the mixing temperature to 60°C, mix for 10 min, and make triangular wraps 8 times; adjust the roller gap to 1 mm, pass through thinly for 15 min, make triangular wraps 10 times, then adjust the roller gap to 6 mm, sheet out and cool to room temperature, and let stand for 48 h to obtain the compound rubber.

[0063] (3) Adjust the gap of the open mill to 1 mm, feed the mixed rubber through the thin pass 8 times for refining, and then feed it into the flat vulcanizing machine for cold pressing for 10 min to obtain the rubber blank. The thickness of the rubber blank is 70% of the target thickness of the modified EPDM rubber composite material. The rubber blank is cut into samples. The weight of the cut rubber blank is 15% more than the theoretical rubber consumption calculated by the mold cavity.

[0064] (4) Place the cut rubber blank into the mold and place it in the flat vulcanizing machine for vulcanization. Control the vulcanization temperature to 170℃, the vulcanization pressure to 18MPa, and the vulcanization time to 25min. After vulcanization, take it out and cool it to room temperature to obtain the modified EPDM rubber composite material.

[0065] Comparative Example 1 Comparative Example 1 did not add a foaming agent, and the remaining components were the same as in Example 1 by mass parts.

[0066] The preparation method of the modified EPDM rubber composite material is the same as that in Example 1, and the thickness of the obtained rubber preform is 120% of the target thickness of the modified EPDM rubber composite material.

[0067] Comparative Example 2 Comparative Example 2 did not contain any special resin, and the remaining components were the same as those in Example 1 by mass.

[0068] The preparation method of the modified EPDM rubber composite material is the same as that in Example 1, and the thickness of the obtained rubber preform is 80% of the target thickness of the modified EPDM rubber composite material.

[0069] Comparative Example 3 Comparative Example 3 did not contain any reactive phosphazene derivatives, and the remaining components were the same as in Example 1 by mass.

[0070] The preparation method of the modified EPDM rubber composite material is the same as that in Example 1, and the thickness of the obtained rubber preform is 80% of the target thickness of the modified EPDM rubber composite material.

[0071] Test Example 1 The modified EPDM rubber composites prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to physical and mechanical property tests, and the test results are shown in Table 1.

[0072] Table 1. Physical and mechanical properties of the modified EPDM rubber composites prepared in Examples 1-3 and Comparative Examples 1-3.

[0073] As shown in Table 1, the density of the modified EPDM rubber composite material prepared in Example 1 is 0.62 g / cm³. 3 The linear ablation rate is 0.12 mm / s, the tensile strength is 4.84 MPa, the elongation at break is 392.57%, the hardness (Shore A) is 64, the thermal conductivity is 0.18 W / (m·K), there is no brittleness under low temperature conditions of -55℃, and the aging resistance (120℃ aging for 72h) has a tensile strength retention rate of 88% and an elongation at break retention rate of 89.26%, which fully meets the requirements for the use of thermal insulation layers in aerospace engines, and also meets the requirements for the external thermal insulation layer of new energy battery packs.

[0074] The density of the modified EPDM rubber composite material prepared in Example 2 is 0.69 g / cm³. 3 It has a linear ablation rate of 0.13 mm / s, a tensile strength of 3.3 MPa, an elongation at break of 242.3%, a hardness (Shore A) of 62, a thermal conductivity of 0.20 W / (m·K), and excellent low-temperature performance, making it suitable for the external thermal insulation layer of new energy battery packs.

[0075] The density of the modified EPDM rubber composite material prepared in Example 3 is 0.68 g / cm³. 3 It exhibits a linear ablation rate of 0.10 mm / s, a tensile strength of 3.5 MPa, an elongation at break of 187.25%, a hardness (Shore A) of 60, a thermal conductivity of 0.19 W / (m·K), and excellent aging resistance (120℃ for 72h), with a tensile strength retention rate of 90% and an elongation at break retention rate of 87.32%. It demonstrates superior ablation and erosion resistance, making it suitable for high-end aerospace insulation applications.

[0076] The density of the modified EPDM rubber composite material prepared in Comparative Example 1 was 1.02 g / cm³. 3 The linear ablation rate was 0.07 mm / s, the tensile strength was 6.8 MPa, the elongation at break was 650%, the hardness (Shore A) was 60, and the aging resistance (120℃ for 72 h) showed a tensile strength retention rate of 111.33% and an elongation at break retention rate of 90.10%. It is evident that the density of the modified EPDM rubber composite material without added foaming agent far exceeds 0.8 g / cm³. 3While it cannot meet the requirements for lightweighting, it achieves the best ablation rate, confirming that the ratio design of the foaming agent, vulcanizing agent, and accelerator in this invention is the key to achieving a balance between low material density and ablation resistance.

[0077] The density of the modified EPDM rubber composite material prepared in Comparative Example 2 was 0.58 g / cm³. 3 The tensile strength was 3.31 MPa, the elongation at break was 315.54%, and the linear ablation rate was 0.15 mm / s. It is evident that the ablation resistance of the modified EPDM rubber composite without added resin is significantly reduced, confirming the crucial role of special resins in improving the ablation resistance and processability of modified EPDM rubber composites.

[0078] The density of the modified EPDM rubber composite material prepared in Comparative Example 3 was 0.60 g / cm³. 3 The tensile strength was 5.3 MPa, the elongation at break was 208.10%, and the linear ablation rate was 0.19 mm / s. It is evident that the ablation resistance of the modified EPDM rubber composite without the addition of phosphazene derivatives decreased significantly, confirming the crucial role of reactive phosphazene derivatives in improving the ablation resistance and flame retardant properties of the modified EPDM rubber composite.

[0079] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A modified EPDM rubber composite material, comprising the following raw materials in parts by mass: 100 parts of EPDM rubber base material, 3-8 parts of activator, 0.5-2.5 parts of antioxidant, 5-15 parts of special resin, 5-15 parts of reactive phosphazene derivative, 5-15 parts of softener, 10-25 parts of reinforcing agent, 10-30 parts of fiber, 3-10 parts of foaming agent, 0.5-3 parts of accelerator and 2-4.5 parts of vulcanizing agent; The special resin includes an inorganic hybrid phenolic resin; the reactive phosphazene derivative is a cyclic phosphazene; the total mass ratio of the accelerator and vulcanizing agent to the foaming agent is 4~6:4~6.

2. The modified EPDM rubber composite material according to claim 1, characterized in that, The EPDM rubber substrate is formed by copolymerization of ethylene, propylene and a third monomer, wherein the third monomer includes ethylene norbornene, 1,4-hexadiene or dicyclopentadiene, and the mass of the third monomer is 3 to 8% of the mass of the EPDM rubber substrate.

3. The modified EPDM rubber composite material according to claim 1, characterized in that, The inorganic hybrid phenolic resin contains inorganic elements including silicon, boron, or barium, and the mass content of the inorganic elements in the inorganic hybrid phenolic resin is 15-30%; the inorganic hybrid phenolic resin includes one or more of hybrid silicon phenolic resin, hybrid boron silicon phenolic resin, or hybrid barium phenolic resin.

4. The modified EPDM rubber composite material according to claim 1, characterized in that, The reactive phosphazene derivatives include six-membered cyclic phosphazenes, wherein the substituents of the six-membered cyclic phosphazenes include one or more of aniline, phenoxy, and allylamino groups.

5. The modified EPDM rubber composite material according to claim 1, characterized in that, The activator includes one or more of zinc oxide, magnesium oxide, and stearic acid; the antioxidant includes one or more of antioxidant 4010NA, antioxidant RD, antioxidant MB, and antioxidant 445; the softener includes one or more of paraffin oil, naphthenic oil, and aromatic oil; the reinforcing agent includes precipitated silica and / or fumed silica; the fiber includes aramid fiber; the foaming agent includes foaming agent OBSH and / or foaming agent AC; the accelerator includes one or more of accelerator CZ, accelerator TMTD, accelerator HA-8, accelerator TAIC, accelerator TRA, accelerator TE, accelerator BZ, and accelerator DM; and the vulcanizing agent includes peroxides and sulfides.

6. The modified EPDM rubber composite material according to claim 5, characterized in that, The peroxide in the vulcanizing agent includes dicumyl peroxide, and the sulfide in the vulcanizing agent includes sulfur-80. The mass ratio of the peroxide to the sulfide is 1.5~3.5:0.5~1. The aramid fiber includes 3mm aramid fiber and / or 6mm aramid fiber.

7. A method for preparing the modified EPDM rubber composite material according to any one of claims 1 to 6, comprising the following steps: The EPDM rubber substrate is plasticized to obtain raw rubber. The raw rubber, activator, antioxidant, reinforcing agent, softener, fiber, special resin, reactive phosphazene derivative, accelerator, vulcanizing agent and foaming agent are mixed and compounded to obtain compound rubber. The compounded rubber is successively kneaded and cold-pressed to obtain a rubber blank; The rubber preform is vulcanized to obtain the modified EPDM rubber composite material.

8. The preparation method according to claim 7, characterized in that, The mixing process includes: first mixing the raw rubber, activator, antioxidant, reinforcing agent, and softener to obtain a first mixed rubber; second mixing the first mixed rubber with fibers to obtain a second mixed rubber; third mixing the second mixed rubber, a special resin, and a reactive phosphazene derivative to obtain a third mixed rubber; and fourth mixing the third mixed rubber, an accelerator, a vulcanizing agent, and a foaming agent to obtain the mixed rubber. The temperature of the first mixing is 40-60°C, and the time is 4-6 minutes; the temperature of the second mixing is 40-60°C, and the time is 10-30 minutes; the temperature of the third mixing is 40-60°C, and the time is 4-6 minutes; and the temperature of the fourth mixing is 20-60°C, and the time is 3-10 minutes.

9. The preparation method according to claim 7, characterized in that, The vulcanization temperature is 150~170℃, the pressure is 12~18MPa, and the time is 15~25min.

10. The application of the modified EPDM rubber composite material according to any one of claims 1 to 6 or the modified EPDM rubber composite material prepared by the preparation method according to any one of claims 7 to 9 in aerospace engines or new energy battery packs.

Images