Sealing tape, preparation method and application thereof

Abstract

The present application relates to the field of sealing materials, and more specifically to a sealing tape and its preparation method and application. The sealing tape, whose structure includes an isolation layer and a sealing layer located on the surface of the isolation layer, the main raw materials of the sealing layer include silicone resin, silicone modified resin, polyimide resin, thermal stabilizer, reinforcing fiber, filler and MQ resin, etc. The sealing tape finally prepared by the present application not only has excellent high temperature resistance, but also can maintain excellent initial adhesion under high temperature environment, ensuring that there is no air leakage during pre-extraction and use; on the other hand, it can also ensure excellent sealing in the vacuum autoclave molding process at 427°C, and greatly reduce the residual glue phenomenon in the subsequent cleaning process, maintain good removability and low odor, effectively meet the performance requirements of the existing technical field for sealing tapes, and has broad application potential.

Description

Technical Field

[0001] The present application relates to the field of sealing materials, and more specifically to a sealing tape and a preparation method and application thereof. Background Art

[0002] With the advancement of materials science, new composite materials have been widely used in the aerospace field in recent years due to their higher strength, modulus, and fatigue resistance compared to metal materials such as steel, aluminum, and titanium. The preparation process for these new composite materials requires vacuum high-temperature hot pressing (typically performed in a vacuum autoclave). Sealing tape is a crucial auxiliary material used to maintain the vacuum during this high-temperature process and is the most important quality assurance method for ensuring that the composite materials are free of defects such as pores.

[0003] In recent years, with the continued research into these new composite materials, particularly the application of high-performance materials such as polyimide (PI) with high heat resistance and strength, the vacuum high-temperature hot press molding temperature for these new composite materials has gradually increased from the initial 120-200°C to the current 300-427°C. Consequently, the performance requirements for the sealing tape auxiliary material used to maintain the vacuum environment have also continued to increase. Sealing tapes must meet the sealing performance requirements at the current high molding temperatures. During the molding process, the sealing tapes must also vulcanize at a matching rate during programmed temperature increases to withstand the internal and external pressure differentials required to maintain the internal vacuum. However, existing sealing tape auxiliary materials generally have the following performance issues: 1. Insufficient initial adhesion or overall bonding, which can easily lead to air leakage during the pre-extraction process and use in the preparation of new composite materials, especially during the high-pressure stage. 2. The sealing performance is reduced at high temperatures, and the vacuum pressure holding capacity is insufficient. 3. The sealing tape's multiple performance properties are prone to performance contradictions, and excessive residual adhesive is left during the cooling stage after use, resulting in more cleaning burdens and increased costs during the process. Summary of the Invention

[0004] Furthermore, how to effectively solve the problems existing in the above-mentioned prior art has become an inevitable topic for researchers in this field. In order to effectively solve the above-mentioned problems, the present applicant has studied and provided a sealing tape and a preparation method thereof. The sealing tape finally prepared by the present application not only has excellent high temperature resistance, but also can maintain excellent initial adhesion in a high temperature environment, ensuring that there is no air leakage during pre-extraction and use; on the other hand, it can also ensure excellent sealing in the vacuum autoclave molding process at 427°C, and greatly reduce the residual glue phenomenon in the subsequent cleaning process, maintain good removability and low odor, effectively meet the performance requirements of the existing technical field for sealing tapes, and has broad application potential.

[0005] The sealing tape comprises an isolation layer and a sealing adhesive layer located on the surface of the isolation layer.

[0006] As a preferred embodiment, the thickness of the isolation layer is 0.05-0.2 mm.

[0007] As a more preferred embodiment, the thickness of the isolation layer is 0.08-0.15 mm.

[0008] As a preferred embodiment, the isolation layer is high temperature resistant release paper.

[0009] As a preferred embodiment, the thickness of the sealant layer is 1.5-3.5 mm.

[0010] As a more preferred embodiment, the thickness of the sealant layer is 2-3 mm.

[0011] As a preferred embodiment, the sealant layer is composed of the following components, in parts by mass: 35 to 82 parts of silicone resin, 2 to 4 parts of silicone modified resin, 4 to 8 parts of polyimide resin, 2 to 5 parts of thermal stabilizer, 1 to 3 parts of reinforcing fiber, 10 to 30 parts of filler, 5 to 10 parts of MQ resin, 4 to 10 parts of silicone oil, 1 to 3 parts of self-healing agent, and 1 to 3 parts of vulcanizing agent.

[0012] As a preferred embodiment, the organic silicone resin is a composition of phenyl vinyl silicone rubber resin and modified octamethylcyclotetrasiloxane resin.

[0013] As a preferred embodiment, the mass ratio of the phenyl vinyl silicone rubber resin to the modified octamethylcyclotetrasiloxane resin is (30-70): (5-12).

[0014] As a preferred embodiment, the mass ratio of the phenyl vinyl silicone rubber resin to the modified octamethylcyclotetrasiloxane resin is (35-50): (8-10).

[0015] As a preferred embodiment, the number average molecular weight Mn of the phenyl vinyl silicone rubber resin is 550,000 to 650,000 Da.

[0016] As a more preferred embodiment, the number average molecular weight Mn of the phenyl vinyl silicone rubber resin is 600,000 to 620,000 Da.

[0017] As a preferred embodiment, the phenyl vinyl silicone rubber resin has a phenyl content of 14 to 20 mol% and a vinyl content of 0.1 to 0.4 mol%.

[0018] As a more preferred embodiment, the phenyl vinyl silicone rubber resin has a phenyl content of 15 to 17 mol % and a vinyl content of 0.2 to 0.3 mol %.

[0019] As a preferred embodiment, the preparation method of the modified octamethylcyclotetrasiloxane resin specifically comprises the following steps: S1: octamethylcyclotetrasiloxane, phenyltrimethoxysilane, vinyltriethoxysilane, trifluoropropylmethylcyclotrisiloxane, and γ-glycidyloxypropyltrimethoxysilane are sequentially added to a reactor, stirred at a speed of 50-70 rpm and deionized water is slowly added, followed by dropwise addition of glacial acetic acid to adjust the pH of the system to 4-4.5, and the temperature is raised to 45-50° C. and stirred at a speed of 200-250 rpm for 2-3 hours to obtain a premix; S2: Tetramethylammonium hydroxide is added to the premixture, and the mixture is stirred evenly at a speed of 150-180 rpm. The mixture is then heated to 80-85° C., the vacuum pressure is controlled at -0.09-0.08 MPa, and dehydration is carried out for 1.5-2 hours. The mixture is then heated to 110-115° C. and kept warm for 6-7 hours to obtain a preproduct. S3: The preproduct is kept at 145-150° C. for 30-40 minutes under nitrogen protection, and then cooled to 120-125° C. to remove low-boiling substances. After completion, the mixture is naturally cooled to room temperature, and the product is taken out and washed through a 300-400 mesh sieve to obtain the product.

[0020] As a preferred embodiment, the mass ratio of octamethylcyclotetrasiloxane, phenyltrimethoxysilane, vinyltriethoxysilane, trifluoropropylmethylcyclotrisiloxane, and γ-glycidyloxypropyltrimethoxysilane is (10~11): (3~3.5): (1~1.2): (1.8~2): (0.6~0.8).

[0021] As a preferred embodiment, the mass ratio of octamethylcyclotetrasiloxane, phenyltrimethoxysilane, vinyltriethoxysilane, trifluoropropylmethylcyclotrisiloxane, and γ-glycidyloxypropyltrimethoxysilane is 10.5:3.3:1.2:1.8:0.7.

[0022] The addition of modified octamethylcyclotetrasiloxane resin can effectively improve the high-temperature resistance, adhesion, and sealing properties of the sealing tape. The high bond energy and thermal stability of the phenyl group make the modified octamethylcyclotetrasiloxane resin less susceptible to breakage at high temperatures, forming a rigid network skeleton that inhibits the thermal motion of the molecular chain and significantly limits the thermal decomposition efficiency of the material. The high bond energy of the Si-O bond inhibits molecular chain breakage at high temperatures, and the cross-linking effect of the vinyl groups forms a more stable internal three-dimensional cross-linked network, increasing the interaction between the molecular chains and enhancing resistance to molecular chain slip. Furthermore, the excellent rotational freedom of the molecular chain segments allows it to adapt to thermal deformation caused by temperatures above 400°C. The excellent capture effect of free radicals inhibits oxidative chain reactions, thereby significantly enhancing the high-temperature resistance, adhesion, and sealing stability of the sealing tape in high-temperature environments above 400°C. The silanol groups on the surface of the silicone rubber form hydrogen bonds or chemical bonds with the substrate, significantly improving the initial adhesion of the tape.

[0023] As a preferred embodiment, the organosilicon-modified resin is an organosilicon-modified polyimide resin.

[0024] As a preferred embodiment, the melt index (MI) of the silicone-modified polyimide resin is 8-14 g / 10 min (295° C. / 6.6 kgf).

[0025] As a preferred embodiment, the glass transition temperature Tg of the silicone-modified polyimide resin is 160-200°C.

[0026] As a preferred embodiment, the polyimide resin is thermoplastic polyimide resin powder.

[0027] As a preferred embodiment, the glass transition temperature Tg of the thermoplastic polyimide resin powder is 300-350°C.

[0028] As a preferred embodiment, the D50 average particle size of the thermoplastic polyimide resin powder is 15-25 μm.

[0029] As a preferred embodiment, the thermal stabilizer is cerium oxide powder or ferric oxide powder or a combination thereof.

[0030] As a preferred embodiment, the thermal stabilizer is cerium oxide powder or ferric oxide powder.

[0031] As a preferred embodiment, the thermal stabilizer is a composition of cerium oxide powder and ferric oxide powder, with a mass ratio of (2.5-3):2.

[0032] As a preferred embodiment, the reinforcing fiber is glass fiber or aramid chopped fiber.

[0033] As a preferred embodiment, the average diameter of the reinforcing fibers is 10-14 μm, and the average length is 1-3 mm.

[0034] As a preferred embodiment, the filler is a composition of silicon dioxide and aluminum hydroxide.

[0035] As a preferred embodiment, the mass ratio of silicon dioxide to aluminum hydroxide is (2-10): (5-20).

[0036] As a more preferred embodiment, the mass ratio of silicon dioxide to aluminum hydroxide is (3-7): (10-20).

[0037] As a preferred embodiment, the MQ resin is vinyl MQ resin.

[0038] As a preferred embodiment, the vinyl content of the vinyl MQ resin is 2-3 wt %.

[0039] As a preferred embodiment, the silicone oil is a composition of vinyl phenyl terminated silicone oil and hydroxy silicone oil.

[0040] As a preferred embodiment, the mass ratio of the vinyl-terminated phenyl silicone oil to the hydroxy silicone oil is (2-4): (2-4).

[0041] As a more preferred embodiment, the mass ratio of the vinyl-terminated phenyl silicone oil to the hydroxy silicone oil is 4:3.

[0042] As a preferred embodiment, the phenyl content of the vinyl-terminated phenyl silicone oil is 28-30 mol%.

[0043] As a preferred embodiment, the hydroxyl content of the hydroxy silicone oil is 8-10 wt%.

[0044] As a preferred embodiment, the self-healing agent is boric acid or boric acid ester.

[0045] As a more preferred embodiment, the self-healing agent is boric acid.

[0046] As a preferred embodiment, the vulcanizing agent is an organic peroxide or a platinum vulcanizing agent.

[0047] As a more preferred embodiment, the vulcanizing agent is an organic peroxide.

[0048] The preparation method of the sealing tape specifically includes the following steps: S1: putting silicone resin, silicone modified resin, polyimide resin, heat stabilizer, reinforcing fiber and filler into a kneader for one-time kneading, stirring at a material temperature of 190-210°C for 2-4 hours, and after completion, pressing the tablet to detect that there are no particles, and then cooling the discharged material to below 80°C to obtain an intermediate; S2: putting MQ resin, silicone oil and self-healing agent into a high-speed stirrer, stirring at 175-185°C and a vacuum degree of -0.10-0.09Mpa for 2-3 hours to obtain a tackifying composition; S3: mixing the intermediate and the tackifying composition The mixture is sequentially put into a kneader for secondary kneading, stirred at a material temperature of 190-210°C for 0.5-1.5 hours, and naturally cooled to room temperature after completion to obtain a base material; S4: The base material is added between the double rollers of an open mill with a cooling function, thinly passed 3-5 times, and then a vulcanizing agent is added, and thinly passed 3-5 times again. The temperature of the whole process is controlled at 50-60°C, and after uniform mixing, a sheet is produced to obtain a sealing rubber compound; S5: The sealing rubber compound is fed into an extruder, the material temperature is controlled at 70-80°C, extruded onto the unwinding isolation layer and passed through a roller press to form a sealing rubber layer. After completion, it is wound up and cut to obtain a sealing tape of the required size.

[0049] In this application, the compound addition of specific silicone resin, silicone modified resin and polyimide resin in the raw materials of the sealant layer can form a sealing resin system with excellent adhesion to the PI film after effective vulcanization, and the compatibility with other raw materials is greatly enhanced through the multi-group and branched structure, so that the sealing tape can effectively improve its mechanical properties and mechanical stability during application, which is beneficial to the sealing effect and subsequent ease of removal; on the other hand, during the preparation process, the sealing resin system and the added tackifying composition system can be compounded to jointly improve the initial adhesion and high temperature resistance, while forming a reversible coordination bond with BO bond as the main body, greatly improving the product's ease of removal and heat-resistant sealing performance.

[0050] The present application further limits the application of the above-mentioned sealing tape in the preparation process of high-performance composite materials for aviation.

[0051] This application has the following beneficial effects:

[0052] 1. The sealing tape provided in the present application not only has excellent high-temperature resistance, but also can maintain excellent initial adhesion in a high-temperature environment, ensuring that no air leakage occurs during pre-extraction and use; on the other hand, it can also ensure excellent sealing in the vacuum autoclave molding process at 427°C, and greatly reduce residual glue in the subsequent cleaning process, maintain good removability and low odor, effectively meet the performance requirements of the existing technical field for sealing tapes, and have broad application potential.

[0053] 2. A sealing tape provided in the present application is not easy to break at high temperatures due to the addition of modified octamethylcyclotetrasiloxane resin, forming a rigid network skeleton, inhibiting the thermal motion of the molecular chain, and greatly limiting the thermal decomposition efficiency of the material. The high bond energy of the Si-O bond inhibits the molecular chain breakage at high temperatures, and through the cross-linking effect of the vinyl group, a more stable internal three-dimensional cross-linked network is formed, thereby increasing the interaction force between the molecular chains and enhancing the resistance to molecular chain slippage. Furthermore, through the excellent rotational freedom of the molecular chain segments, it adapts to the thermal deformation caused by high temperatures above 400°C, and inhibits the oxidative chain reaction through the excellent capture effect of free radicals, thereby greatly enhancing the high temperature resistance, adhesion and sealing stability of the sealing tape in high temperature environments above 400°C.

[0054] 3. A sealing tape provided in the present application is based on the compound addition of specific silicone resin, silicone modified resin and polyimide resin in the raw materials of the sealing layer, which can form a sealing resin system with excellent adhesion to PI film after effective vulcanization, and greatly enhances its compatibility with other raw materials through multi-group and branched structure, so that the sealing tape can effectively improve its mechanical properties and mechanical stability during application, which is beneficial to the sealing effect and subsequent ease of removal. DETAILED DESCRIPTION

[0055] In the specific implementation manner, specific implementation cases will be used to more intuitively display and illustrate the contents of the invention content of this application.

[0056] In the following examples, unless otherwise specified, the raw materials are all commercially available products or can be prepared by methods well known to those skilled in the art.

[0057] Example 1

[0058] The sealing tape comprises an isolation layer and a sealing adhesive layer located on the surface of the isolation layer. The isolation layer is 0.1 mm thick and is made of high-temperature resistant release paper, model 10002, purchased from Shanghai Lianguan Packaging Technology Co., Ltd., China. The sealing adhesive layer is 3 mm thick.

[0059] The sealant layer is composed of the following components, calculated by mass: 45 parts of silicone resin, 2 parts of silicone modified resin, 6 parts of polyimide resin, 5 parts of heat stabilizer, 3 parts of reinforcing fiber, 27 parts of filler, 10 parts of MQ resin, 7 parts of silicone oil, 3 parts of self-healing agent, and 2 parts of vulcanizing agent.

[0060] The organic silicone resin is a composition of phenyl vinyl silicone rubber resin and modified octamethylcyclotetrasiloxane resin, with a mass ratio of 35:10.

[0061] The phenyl vinyl silicone rubber resin has a number average molecular weight Mn of 610,000 Da, a phenyl content of 17 mol %, and a vinyl content of 0.3 mol %, and was purchased from Datian Chemical Additives Research Institute in Panshi City, China, as a DT-1122 product.

[0062] The preparation method of the modified octamethylcyclotetrasiloxane resin, calculated by mass, specifically comprises the following steps: S1: 10.5 parts of octamethylcyclotetrasiloxane, 3.3 parts of phenyltrimethoxysilane, 1.2 parts of vinyltriethoxysilane, 1.8 parts of trifluoropropylmethylcyclotrisiloxane, and 0.7 parts of γ-glycidyloxypropyltrimethoxysilane are sequentially added into a reactor, stirred at 60 rpm and 40 parts of deionized water are slowly added, and then glacial acetic acid is added dropwise to adjust the pH of the system to 4.3, and the temperature is raised to 50°C and the speed is 200 rpm. Stir and react for 2 hours to obtain a premixture; S2: add 0.08 parts of tetramethylammonium hydroxide to the premixture, stir evenly at a speed of 160 rpm, then heat to 85°C, control the vacuum pressure to -0.09 MPa, dehydrate for 1.5 hours, then heat to 110°C, and keep warm for 6 hours to obtain a preproduct; S3: keep the preproduct at 150°C for 35 minutes and protect with nitrogen, then cool to 120°C to remove low-boiling substances, and naturally cool to room temperature after completion. Take out the product and wash it through a 350-mesh sieve to obtain it.

[0063] The silicone-modified resin is a silicone-modified polyimide resin having a melt index (MI) of 12 g / 10 min (295° C. / 6.6 kgf) and a glass transition temperature (Tg) of 170° C. The resin was purchased from Saudi Basic Industries Corporation under the model SILTEM RESINSTM1500.

[0064] The polyimide resin is a thermoplastic polyimide resin powder having a glass transition temperature Tg of 323° C. and an average particle size D50 of 20 μm. The product is purchased as Toughimid-3252 from Suzhou Yuxin Tiancai New Materials Application Technology Co., Ltd. in China.

[0065] The thermal stabilizer was cerium oxide powder, which was purchased from Suzhou Zhengde Rare Earth Materials Co., Ltd. in China and was sold as ZD-9602.

[0066] The reinforcing fibers were glass fibers with an average diameter of 11 μm and an average length of 1 mm, purchased from Jushi Company of China.

[0067] The filler is a composition of silicon dioxide and aluminum hydroxide with a mass ratio of 7:20.

[0068] The MQ resin is a vinyl MQ resin with a vinyl content of 2.7 wt %, purchased from Shandong Dayi Chemical Co., Ltd., China, and sold as model DY-VMQ101.

[0069] The silicone oil is a composition of terminal vinylphenyl silicone oil and hydroxyl silicone oil in a mass ratio of 4:3; the phenyl content of the terminal vinylphenyl silicone oil is 29 mol%, and it is purchased from the AndisilSF2450 model product sold by China Anbiya Special Silicone (Nantong) Co., Ltd.; the hydroxyl content of the hydroxyl silicone oil is 8.5 wt%, and it is purchased from the QJ203 model product sold by China Yangzhou Hongyuan New Materials Co., Ltd.

[0070] The self-healing agent is boric acid; the vulcanizing agent is dicumyl peroxide, which is purchased from Arkema, France, and is a LUPEROX_DC40P-SP2 model product.

[0071] The preparation method of the sealing tape specifically includes the following steps: S1: putting silicone resin, silicone modified resin, polyimide resin, heat stabilizer, reinforcing fiber and filler into a kneader for one-time kneading, stirring at a material temperature of 200°C for 3 hours, and after completion, pressing the tablet to detect that there are no particles, and then cooling the discharged material to below 80°C to obtain an intermediate; S2: putting MQ resin, silicone oil and self-healing agent into a high-speed stirrer, vacuum stirring at 180°C and a vacuum degree of -0.09Mpa for 2 hours to obtain a tackifying composition; S3: mixing the intermediate and the tackifying composition. The compositions are sequentially put into a kneader for secondary kneading, stirred at a material temperature of 200° C. for 1 hour, and naturally cooled to room temperature after completion to obtain a base material; S4: the base material is added between the double rollers of an open mill with a cooling function, thinly passed 4 times, and then a vulcanizing agent is added, and thinly passed 4 more times. The material temperature is controlled at 55° C. throughout the process, and after uniform mixing, a sheet is produced to obtain a sealing rubber compound; S5: the sealing rubber compound is fed into an extruder, the material temperature is controlled at 80° C., extruded onto an unwinding isolation layer, and passed through a roller press to form a sealing rubber layer. After completion, the base material is wound up and cut to obtain a sealing tape of a desired size.

[0072] Example 2

[0073] The only difference between this embodiment and Example 1 is that the sealant layer is composed of the following components, in parts by mass: 58 parts of silicone resin, 2 parts of silicone modified resin, 8 parts of polyimide resin, 5 parts of heat stabilizer, 2 parts of reinforcing fiber, 13 parts of filler, 10 parts of MQ resin, 6 parts of silicone oil, 1 part of self-healing agent, and 3 parts of vulcanizing agent.

[0074] The mass ratio of phenyl vinyl silicone rubber resin to modified octamethylcyclotetrasiloxane resin is 50:8.

[0075] The heat stabilizer is a composition of cerium oxide powder and ferric oxide powder, with a mass ratio of 3:2.

[0076] The reinforcing fiber is aramid short-cut fiber with an average diameter of 12 μm and an average length of 3 mm, which is purchased from Taipron para-aramid-short-cut fiber products sold by China Taihe New Materials Co., Ltd.

[0077] The filler is a composition of silicon dioxide and aluminum hydroxide with a mass ratio of 3:10.

[0078] The silicone oil is a composition of vinyl-terminated phenyl silicone oil and hydroxy silicone oil, with a mass ratio of 2:4.

[0079] Example 3

[0080] The only difference between this embodiment and Example 1 is that the sealant layer is composed of the following components, in parts by mass: 76 parts of silicone resin, 2 parts of silicone modified resin, 4 parts of polyimide resin, 2 parts of heat stabilizer, 1 part of reinforcing fiber, 10 parts of filler, 5 parts of MQ resin, 6 parts of silicone oil, 1 part of self-healing agent, and 1 part of vulcanizing agent.

[0081] The mass ratio of phenyl vinyl silicone rubber resin to modified octamethylcyclotetrasiloxane resin is 70:6.

[0082] The reinforcing fiber is aramid short-cut fiber with an average diameter of 12 μm and an average length of 3 mm, which is purchased from Taipron para-aramid-short-cut fiber products sold by China Taihe New Materials Co., Ltd.

[0083] The filler is a composition of silicon dioxide and aluminum hydroxide with a mass ratio of 3:7.

[0084] The silicone oil is a composition of vinyl-terminated phenyl silicone oil and hydroxy silicone oil, with a mass ratio of 4:2.

[0085] Example 4

[0086] The only difference between this embodiment and Example 1 is that the sealant layer is composed of the following components, in parts by mass: 66 parts of silicone resin, 4 parts of silicone modified resin, 4 parts of polyimide resin, 5 parts of heat stabilizer, 1 part of reinforcing fiber, 13 parts of filler, 10 parts of MQ resin, 6 parts of silicone oil, 1 part of self-healing agent, and 1 part of vulcanizing agent.

[0087] The mass ratio of phenyl vinyl silicone rubber resin to modified octamethylcyclotetrasiloxane resin is 55:11.

[0088] The phenyl vinyl silicone rubber resin has a number average molecular weight Mn of 600,000 Da, a phenyl content of 15 mol %, and a vinyl content of 0.25 mol %, and was purchased from Jiangxi Bluestar Organic Silicone Company, China, as a 785-50U product.

[0089] The heat stabilizer is ferric oxide powder.

[0090] The filler is a composition of silicon dioxide and aluminum hydroxide with a mass ratio of 3:10.

[0091] The silicone oil is a composition of vinyl-terminated phenyl silicone oil and hydroxy silicone oil, with a mass ratio of 4:2.

[0092] Comparative Example 1

[0093] The only difference between this comparative example and Example 1 is that the sealant layer is composed of the following components, in parts by mass: 58 parts of silicone resin, 2 parts of silicone modified resin, 0 parts of polyimide resin, 5 parts of heat stabilizer, 3 parts of reinforcing fiber, 13 parts of filler, 10 parts of MQ resin, 7 parts of silicone oil, 3 parts of self-healing agent, and 2 parts of vulcanizing agent.

[0094] The organic silicone resin is a composition of phenyl vinyl silicone rubber resin and modified octamethylcyclotetrasiloxane resin, with a mass ratio of 56:2.

[0095] The filler is a composition of silicon dioxide and aluminum hydroxide with a mass ratio of 3:10.

[0096] Comparative Example 2

[0097] The only difference between this comparative example and Example 1 is that the sealant layer is composed of the following components, in parts by mass: 55 parts of silicone resin, 2 parts of silicone modified resin, 8 parts of polyimide resin, 1.5 parts of heat stabilizer, 3 parts of reinforcing fiber, 13 parts of filler, 10 parts of MQ resin, 7 parts of silicone oil, 1 part of self-healing agent, and 3 parts of vulcanizing agent.

[0098] The organic silicone resin is a composition of phenyl vinyl silicone rubber resin and modified octamethylcyclotetrasiloxane resin, with a mass ratio of 55:0.

[0099] The filler is a composition of silicon dioxide and aluminum hydroxide with a mass ratio of 3:10.

[0100] The heat stabilizer is ferric oxide powder.

[0101] Comparative Example 3

[0102] The only difference between this comparative example and Example 1 is that the sealant layer is composed of the following ingredients, in parts by mass: 45 parts of silicone resin, 2 parts of silicone modified resin, 6 parts of polyimide resin, 5 parts of heat stabilizer, 3 parts of reinforcing fiber, 27 parts of filler, 10 parts of MQ resin, 7 parts of silicone oil, 0 parts of self-healing agent, and 2 parts of vulcanizing agent.

[0103] Comparative Example 4

[0104] The only difference between this comparative example and Example 1 is that the sealant layer is composed of the following components, in parts by mass: 60 parts of silicone resin, 2 parts of silicone modified resin, 8 parts of polyimide resin, 5 parts of heat stabilizer, 2 parts of reinforcing fiber, 13 parts of filler, 1.5 parts of MQ resin, 7 parts of silicone oil, 2 parts of self-healing agent, and 2 parts of vulcanizing agent.

[0105] The organic silicone resin is a composition of phenyl vinyl silicone rubber resin and modified octamethylcyclotetrasiloxane resin, with a mass ratio of 1:1.

[0106] The heat stabilizer is a composition of cerium oxide powder and ferric oxide powder, with a mass ratio of 3:2.

[0107] The reinforcing fiber is aramid short-cut fiber with an average diameter of 12 μm and an average length of 3 mm, which is purchased from Taipron para-aramid-short-cut fiber products sold by China Taihe New Materials Co., Ltd.

[0108] The filler is a composition of silicon dioxide and aluminum hydroxide with a mass ratio of 3:10.

[0109] Comparative Example 5

[0110] The only difference between this comparative example and Example 1 is that the phenyl vinyl silicone rubber resin is replaced by methyl vinyl silicone rubber with a number average molecular weight Mn of 640,000 Da, a phenyl content of 0 mol%, and a vinyl content of 0.24 mol%, purchased from China Hesheng Silicone Company. Model 110-3 product.

[0111] Comparative Example 6

[0112] The only difference between this comparative example and Example 1 is as follows: The preparation method of the modified octamethylcyclotetrasiloxane resin, calculated by mass, specifically comprises the following steps: S1: 20 parts of octamethylcyclotetrasiloxane, 1.5 parts of phenyltrimethoxysilane, 0.5 parts of vinyltriethoxysilane, 0.6 parts of trifluoropropylmethylcyclotrisiloxane, and 0.2 parts of γ-glycidyloxypropyltrimethoxysilane are added to a reactor in sequence, stirred at 60 rpm and 40 parts of deionized water are slowly added, and then glacial acetic acid is added dropwise to adjust the pH of the system to 4.3, and the temperature is raised to 50°C for 1 h. The mixture was stirred at 200 rpm for 2 hours to obtain a premixture; S2: 0.08 parts of tetramethylammonium hydroxide were added to the premixture, and the mixture was stirred evenly at 160 rpm. The mixture was then heated to 85°C, the vacuum pressure was controlled at -0.09 MPa, and dehydrated for 1.5 hours. The mixture was then heated to 110°C and kept warm for 6 hours to obtain a preproduct; S3: The preproduct was kept at 150°C for 35 minutes under nitrogen protection, and then cooled to 120°C to remove low-boiling substances. After completion, the mixture was naturally cooled to room temperature, and the product was taken out and washed through a 350-mesh sieve to obtain the product.

[0113] Comparative Example 7

[0114] The only difference between this comparative example and Example 1 is that the preparation method of the modified octamethylcyclotetrasiloxane resin, calculated by mass, specifically comprises the following steps: S1: 4.5 parts of octamethylcyclotetrasiloxane, 6.5 parts of phenyltrimethoxysilane, 2.4 parts of vinyltriethoxysilane, 3.2 parts of trifluoropropylmethylcyclotrisiloxane, and 1 part of γ-glycidyloxypropyltrimethoxysilane are added to a reactor in sequence, stirred at 60 rpm and 55 parts of deionized water are slowly added, and then glacial acetic acid is added dropwise to adjust the pH of the system to 4.3, and the temperature is raised to 50°C for 1 h. The mixture was stirred at 200 rpm for 2 hours to obtain a premixture; S2: 0.08 parts of tetramethylammonium hydroxide were added to the premixture, and the mixture was stirred evenly at 160 rpm. The mixture was then heated to 85°C, the vacuum pressure was controlled at -0.09 MPa, and dehydrated for 1.5 hours. The mixture was then heated to 110°C and kept warm for 6 hours to obtain a preproduct; S3: The preproduct was kept at 150°C for 35 minutes under nitrogen protection, and then cooled to 120°C to remove low-boiling substances. After completion, the mixture was naturally cooled to room temperature, and the product was taken out and washed through a 350-mesh sieve to obtain the product.

[0115] Performance evaluation

[0116] Initial adhesion: refer to standard GB / T4852-2002, take the average of 10 tests and record them in Table 1.

[0117] 180° peel force: refer to standard GB / T 2792-2014, and the results are recorded in Table 1 by taking the average of 10 tests.

[0118] High temperature sealing: refer to standard HB 5481-91, temperature and time conditions are: 427℃×4h, the results are recorded in Table 1.

[0119] Removability after high temperature: refer to standard HB 5481-91, temperature and time conditions are: 427℃×4h, the results are recorded in Table 1.

[0120] Heat resistance: refer to standard HB 5481-91, temperature and time conditions are: 427℃×4h, the results are recorded in Table 1.

[0121] Odor: Refer to standard GMW3205, and the results are recorded in Table 2.

[0122] Tensile strength and elongation at break: refer to standard GB / T528-2009. The samples were pre-heated at 427°C for 4 hours. The average value of 10 tests was recorded in Table 2.

[0123]

[0124]

[0125]

[0126]

[0127] Judging from the final performance test results of the Examples and Comparative Examples, Comparative Examples 1-7 achieved worse performance results compared to the Examples. In comparison, Example 2 compared with Comparative Example 1 shows that the thermoplastic polyimide micropowder significantly improves adhesion to the PI film; Example 2 compared with Comparative Example 4 shows that the MQ resin has a greater impact on initial adhesion; Example 2 compared with Comparative Example 5 shows that the choice of phenyl vinyl silicone rubber resin significantly affects heat resistance; Example 1 compared with Comparative Example 3 shows that the tackifying composition facilitates high-temperature sealing and reduces residue. Furthermore, Comparative Example 1 does not use thermoplastic polyimide micropowder, and the high-temperature removability test fails to fully peel, resulting in a large amount of residue. Comparative Example 3 does not use boric acid, and significant air leakage occurs during high-temperature sealing, with a high amount of residue left during high-temperature removal. Comparative Examples 6 and 7 do not produce the best-performing modified resins, resulting in poor overall performance.

Claims

1. A sealing tape, characterized in that: The structure includes an isolation layer and a sealant layer located on the surface of the isolation layer; The thickness of the isolation layer is 0.05-0.2 mm; The isolation layer is high temperature resistant release paper; The thickness of the sealant layer is 1.5 to 3.5 mm; The sealant layer is composed of the following components, calculated by mass: 35-82 parts of silicone resin, 2-4 parts of silicone modified resin, 4-8 parts of polyimide resin, 2-5 parts of heat stabilizer, 1-3 parts of reinforcing fiber, 10-30 parts of filler, 5-10 parts of MQ resin, 4-10 parts of silicone oil, 1-3 parts of self-healing agent, and 1-3 parts of vulcanizing agent; The organic silicone resin is a composition of phenyl vinyl silicone rubber resin and modified octamethylcyclotetrasiloxane resin, with a mass ratio of (30-70): (5-12); The number average molecular weight Mn of the phenyl vinyl silicone rubber resin is 550,000 to 650,000 Da; The phenyl content of the phenyl vinyl silicone rubber resin is 14-20 mol%, and the vinyl content is 0.1-0.4 mol%; The organosilicon-modified resin is an organosilicon-modified polyimide resin with a melt index MI of 8-14 g / 10 min, 295° C. / 6.6 kgf, and a glass transition temperature Tg of 160-200° C.

2. The sealing tape according to claim 1, characterized in that: The preparation method of the modified octamethylcyclotetrasiloxane resin specifically comprises the following steps: S1: adding octamethylcyclotetrasiloxane, phenyltrimethoxysilane, vinyltriethoxysilane, trifluoropropylmethylcyclotrisiloxane, and γ-glycidyloxypropyltrimethoxysilane into a reaction kettle in sequence, stirring at a speed of 50-70 rpm and slowly adding deionized water, then dripping glacial acetic acid to adjust the pH of the system to 4-4.5, heating to 45-50° C., stirring at a speed of 200-250 rpm for 2-3 hours to obtain a premix; S2: in the premix, Tetramethylammonium hydroxide was added to the mixture, and the mixture was stirred at 150-180 rpm, and then the temperature was raised to 80-85°C, the vacuum pressure was controlled at -0.09-0.08 MPa, and dehydrated for 1.5-2 hours. The temperature was then raised to 110-115°C, and the reaction was kept warm for 6-7 hours to obtain a pre-product. S3: The pre-product was kept at 145-150°C for 30-40 minutes under nitrogen protection, and then the temperature was lowered to 120-125°C to remove low-boiling substances. After the temperature was naturally lowered to room temperature, the product was taken out and washed through a 300-400 mesh sieve to obtain the product. The mass ratio of octamethylcyclotetrasiloxane, phenyltrimethoxysilane, vinyltriethoxysilane, trifluoropropylmethylcyclotrisiloxane, and γ-glycidyloxypropyltrimethoxysilane is (10-11): (3-3.5): (1-1.2): (1.8-2): (0.6-0.8).

3. The sealing tape according to claim 2, characterized in that: The polyimide resin is thermoplastic polyimide resin powder.

4. The sealing tape according to claim 3, characterized in that: The glass transition temperature Tg of the thermoplastic polyimide resin powder is 300-350° C.; the average particle size D50 of the thermoplastic polyimide resin powder is 15-25 μm.

5. The sealing tape according to claim 4, characterized in that: The heat stabilizer is cerium oxide powder or ferric oxide powder or a combination thereof.

6. The sealing tape according to claim 5, characterized in that: The reinforcing fibers are glass fibers or aramid chopped fibers; the average diameter of the reinforcing fibers is 10-14 μm, and the average length is 1-3 mm.

7. The sealing tape according to claim 6, characterized in that: The filler is a composition of silicon dioxide and aluminum hydroxide, with a mass ratio of (2-10): (5-20).

8. The sealing tape according to claim 7, characterized in that: The silicone oil is a composition of vinyl-terminated phenyl silicone oil and hydroxy silicone oil, with a mass ratio of (2-4): (2-4).

9. A method for preparing a sealing tape according to any one of claims 1 to 8, characterized in that: The specific steps include: S1: Put the silicone resin, silicone modified resin, polyimide resin, heat stabilizer, reinforcing fiber and filler into a kneader for primary kneading, stir at a material temperature of 190-210°C for 2-4 hours, and after completion, press the tablet to detect that there are no particles, then cool the discharged material to below 80°C to obtain an intermediate; S2: Put the MQ resin, silicone oil and self-healing agent into a high-speed mixer, and vacuum stir at 175-185°C and a vacuum degree of -0.10-0.09 MPa for 2-3 hours to obtain a tackifying composition; S3: Put the intermediate and the tackifying composition into a kneader in sequence for secondary kneading, stir at a material temperature of 190-210°C for 0.5-1.5 hours, and then naturally cool to room temperature to obtain a base material; S4: Add the base material between the two rollers of an open mill with a cooling function, thinly pass it 3 to 5 times, then add the vulcanizer, and continue to thinly pass it 3 to 5 times. The material temperature is controlled at 50-60°C throughout the process. After mixing evenly, the sealing rubber compound is produced into a sheet; S5: Feed the sealing rubber compound into an extruder, control the material temperature at 70-80°C, extrude it onto the unwinding isolation layer and pass it through a roller press to form a sealing rubber layer. After completion, rewind and cut it to obtain a sealing tape of the required size.

10. Use of the sealing tape according to any one of claims 1 to 8 in a process for preparing high-performance composite materials for aviation.

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