High performance rubber gasket for marine cable penetration device and method of making

Abstract

This invention discloses a high-performance rubber gasket for marine cable penetration devices and its preparation method, relating to the field of rubber sealing materials technology. Addressing the problems of degraded mechanical properties of gaskets due to high-filling metal hydroxide halogen-free flame retardants, the lack of physical support in phosphorus-nitrogen binary systems leading to easy collapse of the char layer, the hygroscopic migration of conventional ammonium polyphosphate, and the weak interfacial bonding strength between traditional microencapsulated ammonium polyphosphate and the non-polar rubber matrix, this invention constructs a ternary synergistic flame retardant system by compounding aluminum diethylphosphinate, modified microencapsulated ammonium polyphosphate, and expandable graphite. This achieves highly efficient flame retardancy with an oxygen index of over 32% while simultaneously improving the uniform dispersion and interfacial bonding strength of the flame-retardant filler, effectively inhibiting filler agglomeration and migration, and maintaining the gasket's excellent sealing and resilience performance. This invention is sulfur-free, halogen-free, and does not require external tackifying resin, completely eliminating the chemical corrosion of the ship's paint surface caused by sulfur and the safety hazards of halogen-containing gases, and endowing the rubber gasket with stable surface self-adhesion.

Description

Technical Field

[0001] This invention relates to the field of rubber sealing materials technology, specifically a high-performance rubber gasket for marine cable penetration devices and its preparation method. Background Technology

[0002] Cables on ships and offshore platforms need to be secured and sealed using cable penetration devices when passing through bulkheads and decks.

[0003] The core component of the through-hole device is the rubber gasket, also known as the cable sealing module. To meet ship fire protection requirements, some rubber gaskets are manufactured with halogenated flame retardants. These flame retardants release corrosive and toxic gases during a fire, posing a safety hazard and failing to meet the International Maritime Organization's low-smoke halogen-free protection requirements. In existing technologies, some halogen-free flame retardant solutions rely heavily on adding large amounts of metal hydroxides such as aluminum hydroxide or magnesium hydroxide. High filler content of these metal hydroxides can cause the gasket to lose its mechanical properties. Other halogen-free flame retardant solutions use a phosphorus-nitrogen binary compound flame retardant system, such as aluminum diethylphosphonate with melamine polyphosphate, or aluminum hydroxide with expandable graphite. The former lacks physical expansion locking, resulting in insufficient strength and shrinkage of the char layer at high temperatures; the latter lacks chemical catalytic char formation, leading to a loose and easily detached char layer, potentially drawing heat and fuel into the interior and exacerbating the combustion risk of materials and cables. Furthermore, ordinary ammonium polyphosphate is prone to hygroscopic migration, and the interfacial bonding strength between traditional microencapsulated ammonium polyphosphate and the non-polar rubber matrix is ​​weak.

[0004] Rubber gaskets are typically used to wrap cables in multiple layers, achieving sealing and clamping through compression. When installing multiple layers of gaskets, a certain degree of self-adhesion is needed for temporary fixation to prevent misalignment and slippage during installation. Traditional methods of preparing rubber gaskets achieve self-adhesion by adding tackifying resins, which has drawbacks such as leaving adhesive residue on the bonded surfaces after peeling and poor compatibility with sulfur-free peroxide vulcanization systems, interfering with the cross-linking reaction. Conventional rubber gasket preparation methods often use sulfur vulcanization systems, but the free sulfur remaining in the rubber compound after vulcanization can easily corrode ship hull coatings.

[0005] In summary, to address the aforementioned issues, there is an urgent need in this field to develop a sulfur- and halogen-free flame-retardant gasket for marine cable penetration devices, which is self-adhesive and leaves no residue upon peeling, and its preparation method. This gasket should balance halogen-free flame retardancy with mechanical properties, while simultaneously solving problems such as insufficient synergy in binary flame-retardant systems, uneven dispersion of flame-retardant fillers, sulfur corrosion, and residue after gasket peeling. Summary of the Invention

[0006] The purpose of this invention is to provide a high-performance rubber gasket for marine cable penetration devices and its preparation method, so as to solve the problems raised in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A high-performance rubber gasket for marine cable penetration devices, the rubber gasket comprising the following components, by weight: 85-105 parts of EPDM rubber, 10-40 parts of chlorinated butyl rubber, 3-10 parts by weight of maleic anhydride-grafted EPDM rubber, 2-6 parts of peroxide vulcanizing agent, 1-4 parts of crosslinking agent, 55-80 parts of ternary synergistic flame retardant, 20-60 parts of reinforcing filler, 5-20 parts of plasticizer, 1-5 parts of antioxidant, and 3-8 parts of activator.

[0008] In a more optimized manner, the ternary synergistic flame retardant is a compound of aluminum diethylphosphonate, modified microencapsulated ammonium polyphosphate, and expandable graphite in a mass ratio of (5~10):(2~5):1.

[0009] In a more optimized manner, the preparation steps of the modified microencapsulated ammonium polyphosphate include the following steps: taking melamine-formaldehyde resin, ammonium polyphosphate, and water, stirring and dispersing them evenly, adding acid to adjust the pH, reacting for 30-60 minutes, then heating and reacting for 60-120 minutes, cooling, filtering, washing, and drying to obtain microencapsulated ammonium polyphosphate, uniformly spraying the coupling agent onto the surface of the microencapsulated ammonium polyphosphate particles, stirring, and drying to obtain the modified microencapsulated ammonium polyphosphate.

[0010] More preferably, the coupling agent is any one or more of aluminate coupling agents, titanate coupling agents, and silane coupling agents; the amount of the coupling agent is 0.5 to 3% of the total mass of the microencapsulated ammonium polyphosphate.

[0011] Ideally, the particle size of the expandable graphite is 50-100 mesh.

[0012] More preferably, the peroxide vulcanizing agent is any one or more of dicumyl peroxide, bis-tert-butyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (bis-dipenta); the co-crosslinking agent is any one or more of triallyl isocyanurate and trimethylolpropane trimethacrylate; and the reinforcing filler is any one or more of silica, carbon black, calcium carbonate, kaolin, and barium sulfate.

[0013] More preferably, the plasticizer is any one or more of paraffin oil, naphthenic oil, and aromatic oil; the antioxidant is any one or more of 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 2-mercaptobenzimidazole, N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and 2-thiol-benzimidazole zinc salt; and the activator is any one or more of zinc oxide, magnesium oxide, calcium hydroxide, stearic acid, zinc stearate, diethylene glycol, and diethanolamine.

[0014] In a more optimized manner, the method for preparing the rubber gasket includes the following steps: S1: Add EPDM rubber, chlorinated butyl rubber, reinforcing filler, ternary synergistic flame retardant, plasticizer, antioxidant, and activator to an internal mixer for mixing; S2: Cool down, add peroxide vulcanizing agent and crosslinking agent, mix, discharge the rubber, and obtain the compounded rubber; S3: Pass the compounded rubber through a thin sheet and extrude it; S4: Place the film in the mold and vulcanize; S5: Demolding, trimming, and obtaining the rubber gasket.

[0015] In a more optimized manner, in S1, the mixing temperature is 80~120℃ and the mixing time is 2~5min; in S2, the mixing temperature is 70~90℃ and the mixing time is 1~3min.

[0016] In a more optimized manner, in S4, the vulcanization temperature is 160~180℃, the vulcanization pressure is 10~20MPa, and the vulcanization time is 5~20min.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention employs a ternary synergistic flame retardant system composed of aluminum diethylphosphinate, modified microencapsulated ammonium polyphosphate, and expandable graphite in a mass ratio of (5~10):(2~5):1. In a gaseous environment, aluminum diethylphosphinate rapidly decomposes upon heating, generating phosphorus-containing free radicals such as PO· and HPO2·, which can capture key free radicals H· and OH· in the combustion chain reaction, causing a quenching reaction and achieving flame retardancy. In the condensed phase, the modified microencapsulated ammonium polyphosphate acts as an acid source, catalyzing the dehydration of hydroxyl-containing compounds into char. Ammonia gas dilutes the combustible gas and inflates the char layer, forming an expandable barrier layer. The microencapsulation process achieves the slow release of the ammonium polyphosphate acid source, avoiding the instantaneous decomposition of ordinary ammonium polyphosphate and premature gas generation that impacts the expandable graphite's synchronicity, ensuring the continuity and density of the char layer. Simultaneously, it effectively slows down the rate of material mass loss and blocks heat transfer to the material's interior, cutting off the source of combustion materials and energy, thereby achieving highly efficient flame retardancy. Microencapsulation and coupling agent modification of ammonium polyphosphate create a chemically bonded interface layer on its surface. This layer synergizes with maleic anhydride-grafted EPDM rubber, improving the dispersion uniformity and interfacial bonding strength of the flame-retardant filler at the molecular scale. This effectively inhibits filler aggregation and migration, solving problems such as the hygroscopic migration of ordinary ammonium polyphosphate and insufficient interfacial bonding strength between traditional microencapsulated ammonium polyphosphate and non-polar rubber matrices like EPDM rubber. Expandable graphite expands to form a carbon layer structure, ensuring continuous thermal insulation. This ternary synergistic flame-retardant system achieves a progressive synergy from the gas phase to the condensed phase, and from chemical catalysis to physical locking. This allows for a high-efficiency flame retardant with an oxygen index exceeding 32% with only 66-78 parts of flame retardant added, overcoming the technical bottleneck of traditional high-filler metal hydroxide flame-retardant systems that lead to the deterioration of rubber mechanical properties.

[0018] 2. This invention achieves self-adhesion and residue-free peeling without the addition of external tackifying resin. After blending chlorinated butyl rubber and EPDM rubber, a micro-phase separation structure is formed during vulcanization, with the surface enriched with chlorinated butyl rubber components, thus generating moderate pressure-sensitive adhesion. Simultaneously, the cross-linking network formed by peroxide vulcanization restricts excessive molecular chain migration, maintaining adhesion within a stable range. Self-adhesion on the gasket surface is achieved solely through the combined use of EPDM and chlorinated butyl rubber and the synergistic adjustment of peroxide cross-linking density. The 180° peel force at the rubber-rubber interface of this invention is 0.5–2.5 N / cm, solving the problem of easy residue after peeling of traditional rubber gaskets made with exogenous tackifying resins.

[0019] 3. This invention is sulfur-free and halogen-free, meeting the increasingly stringent low-smoke and halogen-free environmental requirements for ship safety and the International Maritime Organization. This invention employs a peroxide sulfur-free vulcanization system, completely free of sulfur and sulfur-containing compounds, thus completely eliminating the chemical corrosion caused by free sulfur to the ship's paint surface; the halogen-free flame-retardant system avoids the corrosion of metal structures and cable sheaths by halogen precipitation, complying with international environmental regulations. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that the following quantities are by weight. There are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: EPDM rubber: Mooney viscosity ML(1+4) 125°C is 28, ethylene content is 57wt%, ENB content is 7.9wt%; Chlorinated butyl rubber: Mooney viscosity ML(1+8) 125°C is 38, chlorine content is 1.25wt%; Maleic anhydride-grafted EPDM rubber: grafting rate is 1.5%; Silica: Precipitated silica, 1250 mesh; Carbon black: Carbon black N550, 325 mesh; Expandable graphite: 80 mesh; All other raw materials are commercially available analytical grade or industrial grade reagents.

[0022] Example 1: A method for preparing a high-performance rubber gasket for marine cable penetration devices, comprising the following steps: S1: Take 5 parts by weight of melamine-formaldehyde resin, 100 parts by weight of ammonium polyphosphate, and 150 parts by weight of water and stir and disperse them evenly at 65°C. S2: Add dilute hydrochloric acid to adjust the pH to 5 and react for 30 minutes; S3: Heat to 90℃ and react for 60 minutes; S4: Cooling, filtering, washing, and drying at 140℃ to obtain microencapsulated ammonium polyphosphate; S5: Take 3 parts by weight of aluminate coupling agent, heat it to 90℃ to melt it, and then spray it evenly on the surface of 200 parts by weight of microencapsulated ammonium polyphosphate particles. Stir at 110℃ for 40 minutes and dry to obtain modified microencapsulated ammonium polyphosphate.

[0023] S6: When the internal mixer temperature is 80℃, add 95 parts by weight of EPDM rubber, 20 parts by weight of chlorinated butyl rubber, 5 parts by weight of maleic anhydride-grafted EPDM rubber, 30 parts by weight of silica, 20 parts by weight of carbon black, 45 parts by weight of aluminum diethylphosphinate, 25 parts by weight of modified microencapsulated ammonium polyphosphate, 6 parts by weight of expandable graphite, 15 parts by weight of paraffin oil, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of 2-mercaptobenzimidazole, and 1 part by weight of 2,2,4-trimethyl-1,2-dihydroquinoline polymer and mix for 3 minutes, then raise the temperature to 110℃. S7: The temperature is controlled at 85℃. Add 3.5 parts by weight of di-tert-butyl peroxide and 2 parts by weight of triallyl isocyanurate, continue to mix for 2 minutes, discharge the glue, and obtain the compound. S8: Pass the above-mentioned rubber compound through a two-roll mill 4 times to produce sheets; S9: Stack the film to 6mm, put it into the mold of the flat vulcanizing machine, and vulcanize for 12 minutes at a vulcanization temperature of 170℃ and a vulcanization pressure of 15MPa. S10: Demolding, trimming, and obtaining rubber gaskets.

[0024] Example 2: A method for preparing a high-performance rubber gasket for marine cable penetration devices, comprising the following steps: S1: Take 5 parts by weight of melamine-formaldehyde resin, 100 parts by weight of ammonium polyphosphate, and 150 parts by weight of water and stir and disperse them evenly at 65°C. S2: Add dilute hydrochloric acid to adjust the pH to 5 and react for 30 minutes; S3: Heat to 90℃ and react for 60 minutes; S4: Cooling, filtering, washing, and drying at 140℃ to obtain microencapsulated ammonium polyphosphate; S5: Take 3 parts by weight of aluminate coupling agent, heat it to 90℃ to melt it, and then spray it evenly on the surface of 200 parts by weight of microencapsulated ammonium polyphosphate particles. Stir at 110℃ for 40 minutes and dry to obtain modified microencapsulated ammonium polyphosphate.

[0025] S6: When the internal mixer temperature is 80℃, add 95 parts by weight of EPDM rubber, 20 parts by weight of chlorinated butyl rubber, 5 parts by weight of maleic anhydride-grafted EPDM rubber, 30 parts by weight of silica, 20 parts by weight of carbon black, 30 parts by weight of aluminum diethylphosphinate, 30 parts by weight of modified microencapsulated ammonium polyphosphate, 6 parts by weight of expandable graphite, 15 parts by weight of paraffin oil, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of 2-mercaptobenzimidazole, and 1 part by weight of 2,2,4-trimethyl-1,2-dihydroquinoline polymer and mix for 3 minutes, then raise the temperature to 110℃. S7: The temperature is controlled at 85℃. Add 3 parts by weight of di-tert-butyl peroxide and 1.5 parts by weight of triallyl isocyanurate, continue to mix for 2 minutes, discharge the glue, and obtain the compound. S8: Pass the above-mentioned rubber compound through a two-roll mill 4 times to produce sheets; S9: Stack the film to 6mm, put it into the mold of the flat vulcanizing machine, and vulcanize for 12 minutes at a vulcanization temperature of 170℃ and a vulcanization pressure of 15MPa. S10: Demolding, trimming, and obtaining rubber gaskets.

[0026] Example 3: A method for preparing a high-performance rubber gasket for marine cable penetration devices, comprising the following steps: S1: Take 5 parts by weight of melamine-formaldehyde resin, 100 parts by weight of ammonium polyphosphate, and 150 parts by weight of water and stir and disperse them evenly at 65°C. S2: Add dilute hydrochloric acid to adjust the pH to 5 and react for 30 minutes; S3: Heat to 90℃ and react for 60 minutes; S4: Cooling, filtering, washing, and drying at 140℃ to obtain microencapsulated ammonium polyphosphate; S5: Take 3 parts by weight of aluminate coupling agent, heat it to 90℃ to melt it, and then spray it evenly on the surface of 200 parts by weight of microencapsulated ammonium polyphosphate particles. Stir at 110℃ for 40 minutes and dry to obtain modified microencapsulated ammonium polyphosphate.

[0027] S6: When the internal mixer temperature is 80℃, add 95 parts by weight of EPDM rubber, 20 parts by weight of chlorinated butyl rubber, 5 parts by weight of maleic anhydride-grafted EPDM rubber, 30 parts by weight of silica, 20 parts by weight of carbon black, 60 parts by weight of aluminum diethylphosphinate, 12 parts by weight of modified microencapsulated ammonium polyphosphate, 6 parts by weight of expandable graphite, 15 parts by weight of paraffin oil, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of 2-mercaptobenzimidazole, and 1 part by weight of 2,2,4-trimethyl-1,2-dihydroquinoline polymer and mix for 3 minutes, then raise the temperature to 110℃. S7: The temperature is controlled at 85℃. Add 4 parts by weight of di-tert-butyl peroxide and 2.5 parts by weight of triallyl isocyanurate, continue to mix for 2 minutes, discharge the glue, and obtain the compound. S8: Pass the above-mentioned rubber compound through a two-roll mill 4 times to produce sheets; S9: Stack the film to 6mm, put it into the mold of the flat vulcanizing machine, and vulcanize for 12 minutes at a vulcanization temperature of 170℃ and a vulcanization pressure of 15MPa. S10: Demolding, trimming, and obtaining rubber gaskets.

[0028] Comparative Example 1: A flame retardant obtained by compounding aluminum hydroxide and ammonium polyphosphate was used to replace the ternary synergistic flame retardant. The rest was the same as in Example 1. The specific operation is as follows: S1: When the internal mixer temperature is 80℃, add 95 parts by weight of EPDM rubber, 20 parts by weight of chlorinated butyl rubber, 5 parts by weight of maleic anhydride-grafted EPDM rubber, 30 parts by weight of silica, 20 parts by weight of carbon black, 80 parts by weight of aluminum hydroxide, 30 parts by weight of ammonium polyphosphate, 15 parts by weight of paraffin oil, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of 2-mercaptobenzimidazole, and 1 part by weight of 2,2,4-trimethyl-1,2-dihydroquinoline polymer and mix for 3 minutes, then raise the temperature to 110℃. S2: The temperature is controlled at 85℃. Add 3.5 parts by weight of di-tert-butyl peroxide and 2 parts by weight of triallyl isocyanurate, continue to mix for 2 minutes, discharge the glue, and obtain the compound. S3: Pass the above-mentioned rubber compound through a two-roll mill 4 times to produce sheets; S4: Stack the film to 6mm, put it into the mold of the flat vulcanizing machine, and vulcanize for 12 minutes at a vulcanization temperature of 170℃ and a vulcanization pressure of 15MPa. S5: Demolding, trimming, and obtaining the rubber gasket.

[0029] Comparative Example 2: A flame retardant obtained by combining aluminum diethylphosphonate and modified microencapsulated ammonium polyphosphate was used to replace the ternary synergistic flame retardant. The rest of the procedure was the same as in Example 1. The specific operation is as follows: S1: Take 5 parts by weight of melamine-formaldehyde resin, 100 parts by weight of ammonium polyphosphate, and 150 parts by weight of water and stir and disperse them evenly at 65°C. S2: Add dilute hydrochloric acid to adjust the pH to 5 and react for 30 minutes; S3: Heat to 90℃ and react for 60 minutes; S4: Cooling, filtering, washing, and drying at 140℃ to obtain microencapsulated ammonium polyphosphate; S5: Take 3 parts by weight of aluminate coupling agent, heat it to 90℃ to melt it, and then spray it evenly on the surface of 200 parts by weight of microencapsulated ammonium polyphosphate particles. Stir at 110℃ for 40 minutes and dry to obtain modified microencapsulated ammonium polyphosphate.

[0030] S6: When the internal mixer temperature is 80℃, add 95 parts by weight of EPDM rubber, 20 parts by weight of chlorinated butyl rubber, 5 parts by weight of maleic anhydride-grafted EPDM rubber, 30 parts by weight of silica, 20 parts by weight of carbon black, 45 parts by weight of aluminum diethylphosphinate, 25 parts by weight of modified microencapsulated ammonium polyphosphate, 15 parts by weight of paraffin oil, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of 2-mercaptobenzimidazole, and 1 part by weight of 2,2,4-trimethyl-1,2-dihydroquinoline polymer and mix for 3 minutes, then raise the temperature to 110℃. S7: The temperature is controlled at 85℃. Add 3.5 parts by weight of di-tert-butyl peroxide and 2 parts by weight of triallyl isocyanurate, continue to mix for 2 minutes, discharge the glue, and obtain the compound. S8: Pass the above-mentioned rubber compound through a two-roll mill 4 times to produce sheets; S9: Stack the film to 6mm, put it into the mold of the flat vulcanizing machine, and vulcanize for 12 minutes at a vulcanization temperature of 170℃ and a vulcanization pressure of 15MPa. S10: Demolding, trimming, and obtaining rubber gaskets.

[0031] Comparative Example 3: Ordinary ammonium polyphosphate was used instead of modified microencapsulated ammonium polyphosphate, and the rest was the same as in Example 1. The specific operation is as follows: S1: When the internal mixer temperature is 80℃, add 95 parts by weight of EPDM rubber, 20 parts by weight of chlorinated butyl rubber, 5 parts by weight of maleic anhydride-grafted EPDM rubber, 30 parts by weight of silica, 20 parts by weight of carbon black, 45 parts by weight of aluminum diethylphosphinate, 25 parts by weight of ammonium polyphosphate, 6 parts by weight of expandable graphite, 15 parts by weight of paraffin oil, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of 2-mercaptobenzimidazole, and 1 part by weight of 2,2,4-trimethyl-1,2-dihydroquinoline polymer and mix for 3 minutes, then raise the temperature to 110℃. S2: The temperature is controlled at 85℃. Add 3.5 parts by weight of di-tert-butyl peroxide and 2 parts by weight of triallyl isocyanurate, continue to mix for 2 minutes, discharge the glue, and obtain the compound. S3: Pass the above-mentioned rubber compound through a two-roll mill 4 times to produce sheets; S4: Stack the film to 6mm, put it into the mold of the flat vulcanizing machine, and vulcanize for 12 minutes at a vulcanization temperature of 170℃ and a vulcanization pressure of 15MPa. S5: Demolding, trimming, and obtaining the rubber gasket.

[0032] Comparative Example 4: Microencapsulated ammonium polyphosphate was used instead of modified microencapsulated ammonium polyphosphate, and the rest was the same as in Example 1. The specific operation is as follows: S1: Take 5 parts by weight of melamine-formaldehyde resin, 100 parts by weight of ammonium polyphosphate, and 150 parts by weight of water and stir and disperse them evenly at 65°C. S2: Add dilute hydrochloric acid to adjust the pH to 5 and react for 30 minutes; S3: Heat to 90℃ and react for 60 minutes; S4: Cooling, filtering, washing, and drying at 140℃ to obtain microencapsulated ammonium polyphosphate; S5: When the internal mixer temperature is 80℃, add 95 parts by weight of EPDM rubber, 20 parts by weight of chlorinated butyl rubber, 5 parts by weight of maleic anhydride-grafted EPDM rubber, 30 parts by weight of silica, 20 parts by weight of carbon black, 45 parts by weight of aluminum diethylphosphinate, 25 parts by weight of microencapsulated ammonium polyphosphate, 6 parts by weight of expandable graphite, 15 parts by weight of paraffin oil, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of 2-mercaptobenzimidazole, and 1 part by weight of 2,2,4-trimethyl-1,2-dihydroquinoline polymer and mix for 3 minutes, then raise the temperature to 110℃. S6: The temperature is controlled at 85℃. Add 3.5 parts by weight of di-tert-butyl peroxide and 2 parts by weight of triallyl isocyanurate, continue to mix for 2 minutes, discharge the glue, and obtain the compound. S7: Pass the above-mentioned rubber compound through a two-roll mill 4 times to produce sheets; S8: Stack the film to 6mm, put it into the mold of the flat vulcanizing machine, and vulcanize for 12 minutes at a vulcanization temperature of 170℃ and a vulcanization pressure of 15MPa. S9: Demolding, trimming, and obtaining the rubber gasket.

[0033] Comparative Example 5: C5 petroleum resin was used instead of chlorinated butyl rubber, and the rest was the same as in Example 1. The specific operation is as follows: S1: Take 5 parts by weight of melamine-formaldehyde resin, 100 parts by weight of ammonium polyphosphate, and 150 parts by weight of water and stir and disperse them evenly at 65°C. S2: Add dilute hydrochloric acid to adjust the pH to 5 and react for 30 minutes; S3: Heat to 90℃ and react for 60 minutes; S4: Cooling, filtering, washing, and drying at 140℃ to obtain microencapsulated ammonium polyphosphate; S5: Take 3 parts by weight of aluminate coupling agent, heat it to 90℃ to melt it, and then spray it evenly on the surface of 200 parts by weight of microencapsulated ammonium polyphosphate particles. Stir at 110℃ for 40 minutes and dry to obtain modified microencapsulated ammonium polyphosphate.

[0034] S6: When the internal mixer temperature is 80℃, add 95 parts by weight of EPDM rubber, 5 parts by weight of maleic anhydride-grafted EPDM rubber, 8 parts by weight of C5 petroleum resin, 30 parts by weight of silica, 20 parts by weight of carbon black, 45 parts by weight of aluminum diethylphosphinate, 25 parts by weight of modified microencapsulated ammonium polyphosphate, 6 parts by weight of expandable graphite, 15 parts by weight of paraffin oil, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of 2-mercaptobenzimidazole, and 1 part by weight of 2,2,4-trimethyl-1,2-dihydroquinoline polymer and mix for 3 minutes, then raise the temperature to 110℃. S7: The temperature is controlled at 85℃. Add 3.5 parts by weight of di-tert-butyl peroxide and 2 parts by weight of triallyl isocyanurate, continue to mix for 2 minutes, discharge the glue, and obtain the compound. S8: Pass the above-mentioned rubber compound through a two-roll mill 4 times to produce sheets; S9: Stack the film to 6mm, put it into the mold of the flat vulcanizing machine, and vulcanize for 12 minutes at a vulcanization temperature of 170℃ and a vulcanization pressure of 15MPa. S10: Demolding, trimming, and obtaining rubber gaskets.

[0035] Comparative Example 6: The sulfur-based vulcanization system was replaced with a sulfur-based vulcanization system, and the rest was the same as in Example 1. The specific operation is as follows: S1: Take 5 parts by weight of melamine-formaldehyde resin, 100 parts by weight of ammonium polyphosphate, and 150 parts by weight of water and stir and disperse them evenly at 65°C. S2: Add dilute hydrochloric acid to adjust the pH to 5 and react for 30 minutes; S3: Heat to 90℃ and react for 60 minutes; S4: Cooling, filtering, washing, and drying at 140℃ to obtain microencapsulated ammonium polyphosphate; S5: Take 3 parts by weight of aluminate coupling agent, heat it to 90℃ to melt it, and then spray it evenly on the surface of 200 parts by weight of microencapsulated ammonium polyphosphate particles. Stir at 110℃ for 40 minutes and dry to obtain modified microencapsulated ammonium polyphosphate.

[0036] S6: When the internal mixer temperature is 80℃, add 95 parts by weight of EPDM rubber, 20 parts by weight of chlorinated butyl rubber, 5 parts by weight of maleic anhydride-grafted EPDM rubber, 30 parts by weight of silica, 20 parts by weight of carbon black, 45 parts by weight of aluminum diethylphosphinate, 25 parts by weight of modified microencapsulated ammonium polyphosphate, 6 parts by weight of expandable graphite, 15 parts by weight of paraffin oil, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of 2-mercaptobenzimidazole, and 1 part by weight of 2,2,4-trimethyl-1,2-dihydroquinoline polymer and mix for 3 minutes, then raise the temperature to 110℃. S7: The temperature is controlled at 85℃. Add 1.5 parts by weight of sulfur, 1.5 parts by weight of N-cyclohexyl-2-benzothiazole sulfenamide and 0.5 parts by weight of tetramethylthiuram disulfide, continue to mix for 2 minutes, discharge the rubber, and obtain the compound. S8: Pass the above-mentioned rubber compound through a two-roll mill 4 times to produce sheets; S9: Stack the film to 6mm, put it into the mold of the flat vulcanizing machine, and vulcanize for 12 minutes at a vulcanization temperature of 170℃ and a vulcanization pressure of 15MPa. S10: Demolding, trimming, and obtaining rubber gaskets.

[0037] Performance Testing: The rubber gaskets obtained in the examples and comparative examples were tested for tensile strength according to GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber"; the oxygen index of the rubber gasket samples was tested according to GB / T2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test"; the peel force of the rubber gasket samples was tested by peeling at 180° with rubber-rubber interface according to GB / T 2792-2014 "Test Method for Peel Strength of Adhesive Tapes"; the halogen content of the rubber gasket samples was tested according to GB / T 34692-2017 "Determination of Halogen Content in Thermoplastic Elastomers - Oxygen Bomb Combustion-Ion Chromatography"; the sulfur content of the rubber gasket samples was tested according to GB / T 40723-2021 "Determination of Total Sulfur and Total Nitrogen Content in Rubber - Automatic Analyzer Method"; and the pH value was determined according to GB / T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test"; and the pH value was determined according to GB / T 2792-2014 "Test Method for Peel Strength of Adhesive Tapes ... Following the test logic of GB / T 14834-2009 "Determination of Adhesion and Corrosion Effect of Vulcanized Rubber or Thermoplastic Rubber to Metal", the rubber gasket samples were placed in a constant temperature and humidity chamber and exposed to 50℃×95%RH for 14 days. After separation, the paint surface was rated according to GB / T 1766-2008 "Rating Method for Aging of Paint and Varnish Coatings". The results are shown in Table 1 below. Table 1

[0038] Conclusion: As can be seen from the data in the table above, the high-performance rubber gasket for marine cable penetration device and its preparation method of the present invention have the following significant innovations and beneficial effects: The high-performance rubber gasket for the marine cable penetration device of the present invention adopts a ternary synergistic flame retardant system obtained by compounding aluminum diethylphosphinate, modified microencapsulated ammonium polyphosphate and expandable graphite in a mass ratio of (5~10):(2~5):1 during the preparation process, which constructs a progressive synergistic flame retardant from the gas phase to the condensed phase, and from chemical catalysis to physical locking.

[0039] As can be seen from Example 1 and Comparative Example 1, the traditional metal hydroxide-filled flame retardant scheme requires 110 parts by weight of flame retardant, achieving an oxygen index of only 28% and a tensile strength of only 7.5 MPa. In contrast, the ternary synergistic flame retardant system reduces the amount of flame retardant by 34 parts by weight, achieving an oxygen index of 35.5%, an increase of 7.5 percentage points, and a tensile strength of 14.8 MPa, an increase of 97.3%. This achieves highly efficient flame retardancy and superior mechanical properties, while also considering halogen-free flame retardancy and sealing resilience.

[0040] As can be seen from Example 1 and Comparative Example 2, the oxygen index of the product obtained by the phosphorus-nitrogen binary system without expandable graphite drops sharply to 27.5%, which is 8 percentage points lower than that of the ternary synergistic flame retardant system. This verifies that expandable graphite is the core pillar of the ternary synergistic flame retardant system. The carbon layer without physical support is prone to collapse at high temperatures, and expandable graphite provides a stable heat insulation barrier.

[0041] As can be seen from Example 1 and Comparative Example 3, when using ordinary ammonium polyphosphate, compared with the ternary synergistic flame retardant system, the tensile strength is reduced by 1.8 MPa and the oxygen index is reduced by 7 percentage points because ordinary ammonium polyphosphate is prone to moisture absorption and migration. The water-carrying shell of the microcapsule blocks environmental moisture, inhibits the moisture absorption and migration of ammonium polyphosphate, and ensures long-term flame retardant effectiveness.

[0042] As shown in Example 1 and Comparative Example 4, under the condition that the total amount of flame retardant filling agent and the ratio of the ternary synergistic flame retardant system are exactly the same, the tensile strength of microencapsulated ammonium polyphosphate without secondary surface modification treatment with coupling agent is only 12.5 MPa, and the oxygen index is only 12.0%. This invention uses modified microencapsulated ammonium polyphosphate with secondary surface treatment by aluminate coupling agent to form a chemically bonded interface layer, which synergistically inhibits the agglomeration and migration of flame retardant fillers with maleic anhydride-grafted EPDM rubber, significantly improving the dispersion uniformity and interfacial bonding strength of the flame retardant filler. With more uniform filler dispersion, mechanical properties are improved, and the expanded char layer during combustion is more continuous and dense, resulting in higher flame retardant efficiency. The tensile strength increased from 12.5 MPa to 14.8 MPa, an increase of 18.4%; the oxygen index increased from 32.0% to 35.5%.

[0043] As shown in Example 1 and Comparative Example 5, although the initial peel strength was increased by 0.4 N / cm with the addition of C5 petroleum resin as an external tackifying resin, the tensile strength was reduced by 3.3 MPa compared to the chlorinated butyl rubber internal tackifying solution. Furthermore, the external tackifying resin is a physical blend and does not participate in crosslinking, resulting in residue after peeling. The chlorinated butyl rubber internal tack solution of this invention, through the participation of chlorinated butyl rubber in the peroxide sulfur-free vulcanization system, imparts self-adhesiveness to the gasket, leaving no residue after peeling.

[0044] As shown in Example 1 and Comparative Example 6, after the gaskets made with the sulfur vulcanization system were tested in contact with marine epoxy paint, the paint surface showed obvious yellowing and bubble level ≥3. In contrast, the paint surface of the peroxide vulcanized gaskets did not show yellowing or bubbles. The peel force of the sulfur vulcanized gaskets was reduced by 0.4 N / cm compared with the peroxide-free gaskets. This verifies that the free sulfur remaining in the sulfur vulcanization system migrates to the hull paint surface under humid and hot conditions, causing chemical corrosion. The peroxide-free vulcanization system eliminates the potential corrosion of the hull paint surface by free sulfur at the source.

[0045] The high-performance rubber gasket for marine cable penetration devices of the present invention has industrial applicability. The rubber gasket and its preparation method provided by the present invention can be industrially applied to the production of marine cable penetration devices, and can also be used in other sealing applications requiring sulfur-free, halogen-free, flame-retardant, self-adhesive, and residue-free sealing after peeling, such as offshore wind power, rail transportation, and chemical equipment.

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A high-performance rubber gasket for a marine cable penetration device, characterized in that: The rubber gasket comprises the following components, by weight: 85-105 parts of EPDM rubber, 10-40 parts of chlorinated butyl rubber, 3-10 parts by weight of maleic anhydride-grafted EPDM rubber, 2-6 parts of peroxide vulcanizing agent, 1-4 parts of crosslinking agent, 55-80 parts of ternary synergistic flame retardant, 20-60 parts of reinforcing filler, 5-20 parts of plasticizer, 1-5 parts of antioxidant, and 3-8 parts of activator.

2. The high-performance rubber gasket for a marine cable penetration device according to claim 1, characterized in that: The ternary synergistic flame retardant is a compound of aluminum diethylphosphonate, modified microencapsulated ammonium polyphosphate, and expandable graphite in a mass ratio of (5~10):(2~5):

1.

3. The high-performance rubber gasket for a marine cable penetration device according to claim 2, characterized in that: The preparation steps of the modified microencapsulated ammonium polyphosphate include the following steps: taking melamine-formaldehyde resin, ammonium polyphosphate, and water, stirring and dispersing evenly, adding acid to adjust the pH, reacting for 30-60 minutes, then heating up and reacting for 60-120 minutes, cooling down, filtering, washing, and drying to obtain microencapsulated ammonium polyphosphate, uniformly spraying the coupling agent onto the surface of the microencapsulated ammonium polyphosphate particles, stirring, and drying to obtain the modified microencapsulated ammonium polyphosphate.

4. The high-performance rubber gasket for a marine cable penetration device according to claim 3, characterized in that: The coupling agent is any one or more of aluminate coupling agents, titanate coupling agents, and silane coupling agents; the amount of the coupling agent is 0.5 to 3% of the total mass of the microencapsulated ammonium polyphosphate.

5. A high-performance rubber gasket for a marine cable penetration device according to claim 2, characterized in that: The expandable graphite has a particle size of 50-100 mesh.

6. The high-performance rubber gasket for a marine cable penetration device according to claim 1, characterized in that: The peroxide vulcanizing agent is any one or more of dicumyl peroxide, bis-tert-butyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (bis-di-pentane); the co-crosslinking agent is any one or more of triallyl isocyanurate and trimethylolpropane trimethacrylate; and the reinforcing filler is any one or more of silica, carbon black, calcium carbonate, kaolin, and barium sulfate.

7. The high-performance rubber gasket for a marine cable penetration device according to claim 1, characterized in that: The plasticizer is any one or more of paraffin oil, naphthenic oil, and aromatic oil; the antioxidant is any one or more of 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 2-mercaptobenzimidazole, N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and 2-thiol-benzimidazole zinc salt; the activator is any one or more of zinc oxide, magnesium oxide, calcium hydroxide, stearic acid, zinc stearate, diethylene glycol, and diethanolamine.

8. A method for preparing a high-performance rubber gasket for a marine cable penetration device according to claim 1: characterized in that, The method for preparing the rubber gasket includes the following steps: S1: Add EPDM rubber, chlorinated butyl rubber, reinforcing filler, ternary synergistic flame retardant, plasticizer, antioxidant, and activator to an internal mixer for mixing; S2: Cool down, add peroxide vulcanizing agent and crosslinking agent, mix, discharge the rubber, and obtain the compounded rubber; S3: Pass the rubber compound through a thin sheet and extrude it; S4: Place the film in the mold and vulcanize; S5: Demolding, trimming, and obtaining the rubber gasket.

9. The method for preparing a high-performance rubber gasket for a marine cable penetration device according to claim 8, characterized in that: In S1, the mixing temperature is 80~120℃ and the mixing time is 2~5min; in S2, the mixing temperature is 70~90℃ and the mixing time is 1~3min.

10. The method for preparing a high-performance rubber gasket for a marine cable penetration device according to claim 8, characterized in that: In S4, the vulcanization temperature is 160~180℃, the vulcanization pressure is 10~20MPa, and the vulcanization time is 5~20min.

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