A method for preparing an elastic silicone material with shape memory function and a sleeve thereof

Abstract

The application provides a preparation method of an elastic silicone material with a shape memory function and a sleeve thereof, and relates to the technical field of silicone rubber materials. The elastic silicone material with the shape memory function comprises the following components: a solid silicone polymer containing a phenyl functional group, a silicone rubber, a flame retardant, a catalyst and a phenyl polyester silicone wax. The application also provides a preparation method of an elastic silicone sleeve with the shape memory function produced by the above material. The elastic silicone sleeve with the shape memory function provided by the application has the characteristics of good flame retardancy, low hardness, bending fatigue resistance, high-temperature resistance and low-temperature resistance, and can be applied to electrically driven vehicles, electronic industries and other scenes in the aspect of bending fatigue resistance and high and low temperature resistance insulation protection.

Description

Technical Field

[0001] This invention relates to the field of silicone rubber materials technology, specifically to an elastic silicone resin material with shape memory function and a method for preparing its sleeve. Background Technology

[0002] Silicone resins are thermosetting polyorganosiloxanes with a highly cross-linked structure. Due to their unique structure, compared with other organic resins, they possess superior heat resistance, cold resistance, weather resistance, electrical insulation, hydrophobicity, and anti-sticking and mold release properties. Therefore, they are widely used as high and low temperature resistant insulating varnishes, heat-resistant coatings, weather-resistant coatings, ablation-resistant coatings, and high and low temperature resistant and electrically insulating molding compounds. Research on the modification of thermoplastic resins with solid phenyl silicone resins focuses on improving the high-temperature resistance, mechanical properties, and chemical resistance and electrical insulation of thermoplastic resins. Pure resins are rarely used in applications requiring resistance to bending fatigue. Furthermore, research on the application of solid phenyl silicone resins in heat-shrinkable shape memory materials is scarce.

[0003] Chinese patent CN 101157802 B discloses a silicone rubber material with shape memory function and its preparation method. The method involves mixing eucommia gum or fluororubber and thermoplastic resins such as PE, PP, or EVA into a compounded silicone rubber. The mixture is then molded or extruded, and compressed, stretched, inflated, and cooled to set the shape at 50-250℃ to obtain heat-shrinkable silicone rubber tapes, heat-shrinkable tubes, or silicone shaped parts. The tear strength of this product is 14-20 N / mm, and the hardness is in the range of 65-75A. The tear strength of this product is not ideal.

[0004] Chinese Patent CN 101993589 B discloses a silicone rubber heat shrink tubing and its preparation method. The method uses silicone rubber, including dimethyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ), and methyl phenyl vinyl silicone rubber (PVMQ), mixed with one or more thermoplastic resins selected from (phenyl silicone resin, phenylene silicone resin, methyl silicone resin, vinyl silicone resin, acrylic resin, ethylene vinyl acetate copolymer (EVA), ethylene ethyl acrylate copolymer (EEA), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE)) to prepare the silicone heat shrink tubing. The silicone rubber heat shrink tubing provided by this invention has good stability, high heat resistance, and cold resistance; however, its tear strength and flexural fatigue resistance are insufficient.

[0005] However, existing studies have shown that in silicone rubber / EVA composites, as the amount of EVA increases, the mechanical properties of the composites increase, but their thermal stability decreases (Study on the blending modification of silicone rubber compound by EVA [J] Materials Reports, 2010.5(24):415-424.); Other studies have found that as the amount of EVA added increases, the retention rate of mechanical properties of silicone rubber after aging decreases significantly, and the addition of EVA will greatly reduce the service temperature of silicone rubber blends (Study on the thermo-oxidative aging properties of silicone rubber / EVA blends: II. The role of antioxidants [J]. Elastomers, 1993,3(2):6.).

[0006] Currently, silicone rubber heat shrink tubing is widely used in power, motor, automotive, electronics, and aerospace industries due to its excellent temperature resistance and insulation properties. However, the performance of existing silicone rubber heat shrink tubing, especially its long-term high-temperature resistance, flexural fatigue resistance, and flame retardancy, is still not ideal and cannot meet the stringent requirements of complex electrical systems such as those in new energy vehicles. The addition of polyolefin thermoplastic resins to achieve shape memory function actually lowers the service temperature and aging temperature of the silicone rubber blend (i.e., shortens the material's lifespan). Alternatively, to obtain better flame retardancy, large amounts of additive inorganic fillers such as silica, flame retardants such as antimony trioxide synergistic halogen flame retardants, magnesium hydroxide, and aluminum hydroxide are often added to enhance the flame retardancy of the silicone rubber mixture. However, excessive inorganic flame retardants can lead to a decrease in the insulation and withstand voltage performance, tear resistance, flexibility, and flexural fatigue resistance of silicone rubber heat shrink tubing, as well as a significant decrease or even loss of key properties such as expansion and contraction.

[0007] Based on this, the present invention provides an elastic silicone resin material with shape memory function and its preparation method. By screening and optimizing its components, the final product not only has high tear strength and good flame retardancy, but also resistance to bending fatigue, thus making up for the shortcomings of the prior art. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides an elastic silicone resin material with shape memory function. Its main components include a solid silicone resin polymer containing phenyl functional groups, an addition-curing silicone rubber, a composite flame retardant, a two-component platinum catalyst, and phenyl polyester silicone wax. It not only possesses excellent flame retardancy but also resistance to bending fatigue, making it suitable for applications such as electric vehicles and the electronics industry requiring bending fatigue resistance and high / low temperature insulation protection.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] On one hand, the present invention provides an elastic silicone resin material with shape memory function, comprising the following components: a solid silicone resin polymer containing phenyl functional groups, silicone rubber, a composite flame retardant, a catalyst, and phenyl polyester silicone wax.

[0011] Preferably, the elastic silicone resin material comprises, by weight, the following components: 95-110 parts of a solid silicone resin polymer containing phenyl functional groups, 75-125 parts of silicone rubber, 9-35 parts of a composite flame retardant, 0.4-1 parts of a catalyst, and 0.3-2.5 parts of phenyl polyester silicone wax.

[0012] More preferably, the elastic silicone resin material comprises, by weight, the following components: 98-100 parts of a solid silicone resin polymer containing phenyl functional groups, 78-120 parts of silicone rubber, 10-32 parts of a composite flame retardant, 0.5-0.8 parts of a catalyst, and 0.5-2 parts of phenyl polyester silicone wax.

[0013] Preferably, the melting point of the solid silicone resin polymer containing phenyl functional groups is 70-90°C; more preferably, the melting point of the solid silicone resin polymer containing phenyl functional groups is 75-85°C.

[0014] Preferably, the silicone rubber is an addition-curing silicone rubber;

[0015] Preferably, the addition-curing silicone rubber is added with A / B (0.4-0.5 / 0.6-0.7) and vulcanized at 195-205°C for 1.5-3 hours; more preferably, the addition-curing silicone rubber is added with A / B (0.5 / 0.7) and vulcanized at 200°C for 2 hours.

[0016] Preferably, the addition-cured silicone rubber has a hardness of 40A-50A, a tensile strength ≥9MPa after two-stage curing, an elongation at break ≥800%, and a tear strength ≥30N / mm.

[0017] Preferably, the composite flame retardant is a combination of platinum flame retardant and aluminum hydroxide. More preferably, the mass ratio of the platinum flame retardant to the aluminum hydroxide flame retardant is 1:90-110; even more preferably, the mass ratio is 1:100.

[0018] Preferably, the platinum flame retardant is a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex.

[0019] Preferably, the PT content of the 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex is 4500-5200 ppm; more preferably, the PT content of the 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex is 5000 ppm.

[0020] Preferably, the catalyst is a two-component platinum catalyst.

[0021] Preferably, the melting temperature of the phenyl polyester silicone wax is 50-70°C; more preferably, the melting temperature of the phenyl polyester silicone wax is 55-65°C.

[0022] Preferably, the elastic silicone resin material comprises, by weight, the following components: 100 parts of a solid silicone resin polymer containing phenyl functional groups, 80-120 parts of addition-curing silicone rubber, 0.1-0.3 parts of platinum flame retardant, 10-30 parts of aluminum hydroxide, 0.5-0.8 parts of a two-component platinum catalyst, and 0.5-2 parts of phenyl polyester silicone wax.

[0023] The technical solution of this invention uses solid silicone resin containing phenyl functional groups as the main base material, which can endow the material with excellent oxidation stability, thermal stability, weather resistance, and electrical insulation. Furthermore, the mechanism of using only solid phenyl silicone resin lies in its cross-linked semi-inorganic polymer with -Si-O-Si- as the main chain and organic groups linked to silicon atoms. This structure determines that phenyl silicone resin has unique properties, possessing characteristics of both carbon-based plastics and silicon materials. The presence of free positions and carbon-silicon bonds in the molecular chain of phenyl silicone resin gives it thermoplasticity, which is also the main mechanism of application in this invention. When phenyl silicone resin is heated to a certain temperature, the molecular chain breaks under the action of carbon-silicon bonds, forming free radicals and initiating a cross-linking reaction, forming a three-dimensional network structure of silicon oxide compounds, thereby achieving a reinforcing effect. This organic-based and inorganic polymer exhibits glassy solid properties below its melting point (at room temperature) and softening and melting melt properties above its melting point. This property manifests in two different forms when applied to shape memory functions: at room temperature, solid phenyl silicone resin is solid, freezing the molecular chain movement of the elastic silicone resin material, thus acting as a "frozen chain" effect; when the material is heated above the softening point of solid phenyl silicone resin, the molecular chains of the material relax, thus acting as a "thawing" effect.

[0024] Therefore, addition-cured silicone rubber is added to solid phenyl silicone resin. The purpose is to utilize the addition-cured silicone rubber, which can maintain elasticity for a long time in a temperature range of -65 to 200℃. It also possesses excellent electrical properties and chemical stability, water resistance, ozone resistance, radiation resistance, weathering resistance, hydrophobicity and moisture resistance, shock resistance, good low compression set, and low flammability. Furthermore, it is physiologically inert, non-toxic, odorless, and the curing rate can be easily controlled by temperature. To give it elasticity, good mechanical properties, flexural fatigue resistance, and high tear resistance, the addition-cured silicone rubber used in this technical solution has the following key characteristics: 40A-50A, tensile strength after two-stage curing is above 9MPa, elongation at break is above 800%, and tear strength is greater than 30N / mm. This endows the material with good mechanical properties and flexibility.

[0025] To meet the flame-retardant performance requirements of the material, a composite flame retardant is added. A trace amount of platinum flame retardant, synergistically combined with a small amount of hydroxide flame retardant, imparts excellent flame-retardant properties while maximizing the preservation of the material's insulation properties, low hardness, resistance to bending fatigue, and resistance to high and low temperatures. The platinum flame retardant is a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex, a highly active and efficient platinum catalyst that efficiently catalyzes the addition reactions of Si-Vi and Si-H without side reactions. Even in high concentrations, platinum flame retardant alone cannot achieve the flame-retardant function of silicone rubber; therefore, it must be used in conjunction with a hydroxide flame retardant.

[0026] To achieve the shape memory function of the material, a two-component platinum catalyst is added to induce thermal cross-linking of the silicone molecular chains in the addition-cure silicone rubber at room temperature / high temperature. It should be noted that the addition-cure silicone rubber used in this technical solution has the following key characteristics: 40A-50A silicone rubber exhibits a tensile strength exceeding 9 MPa, an elongation at break exceeding 800%, and a tear strength greater than 30 N / mm after two-stage vulcanization. This endows the material with excellent mechanical and flexible properties; in other words, its mechanical properties are obtained through vulcanization cross-linking. It should be noted that the key characteristic of using solid phenyl silicone resin in this technical solution is that pure cross-linked silicone rubber does not possess heat-shrinking properties. The addition of solid phenyl silicone resin, with a melting point of 70-90℃, utilizes the glassy solid properties of solid phenyl silicone resin after processing. Below its melting point (at room temperature), it exhibits a glassy solid state, while above its melting point, it softens. This property manifests in two different forms in shape memory: at room temperature, the solid phenyl silicone resin is solid, freezing the network structure formed by the vulcanized cross-linked silicone rubber and restricting the movement of the silicone resin molecular chains, acting as a "frozen chain" effect. When the material is heated above the softening point of the solid phenyl silicone resin, the network structure formed by the vulcanized cross-linked silicone rubber relaxes, acting as a "thawing" effect, thus achieving the heat shrinkage function. In this process, the main role of the solid phenyl silicone resin is to support the expansion, cooling, and shaping function of the vulcanized cross-linked silicone rubber, without participating in the vulcanization and cross-linking of the silicone rubber.

[0027] To meet the processing performance requirements of the material, phenyl polyester silicone wax is added. The purpose and function of this addition is that the functional groups contained in phenyl polyester silicone wax are consistent with those contained in solid phenyl silicone resin, which not only provides good compatibility but also improves the processing performance of the material, making it easier for the various components to be fully and uniformly mixed.

[0028] On the other hand, the present invention provides a method for preparing an elastic silicone resin sleeve with shape memory function, characterized in that it uses the above-mentioned elastic silicone resin material as raw material and includes the following steps:

[0029] S1: A solid silicone resin polymer containing phenyl functional groups, silicone rubber, composite flame retardant, and phenyl polyester silicone wax are heated and kneaded under vacuum to obtain premixed polymer A.

[0030] S2: Premixed polymer A is cooled to ≤30℃, refined, and then a two-component platinum catalyst is added for secondary refining to obtain rubber compound B;

[0031] S3: Rubber compound B is extruded at a temperature ≤30℃, and formed into a tubular preform through a mold. It is then thermosetting and vulcanizing at 500-650℃, and further thermosetting and crosslinking at 200-380℃ to obtain preform C.

[0032] S4: Heat and soften the tube blank C at 130-280℃, expand it to 1-3 times its original size, and cool and shape it at 0-22℃ to obtain an elastic silicone sleeve with shape memory function.

[0033] Preferably, the heating temperature in S1 is 90-115°C; more preferably, the heating temperature in S1 is 100-105°C.

[0034] Preferably, the kneading speed in S1 is 5-55 Rpm, and the kneading time is 10-45 min; more preferably, the kneading speed in S1 is 10-50 Rpm, and the kneading time is 15-40 min.

[0035] Preferably, the vacuum degree of the vacuum in S1 is -0.03 to -1 MPa, and the time is 1 to 10 min; more preferably, the vacuum degree of the vacuum in S1 is -0.06 to -1 MPa, and the time is 1 to 5 min.

[0036] Preferably, the specific refining conditions described in S2 are as follows: open mill roll temperature ≤30℃, open mill roll spacing 10-20mm, refining 10-20 times, open mill roll spacing 1-2mm, refining 2-3 times, and finally producing sheets with a thickness of 20-30mm.

[0037] More preferably, the specific conditions for the secondary refining described in S2 are as follows: open mill roll temperature of 20-25℃, open mill roll spacing of 8-10mm, refining 15-20 times, or open mill roll spacing of 1-2mm, refining 2-3 times. Finally, the sheet is produced at 30mm.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The technical solution of this invention optimizes the composition and ratio of elastic silicone resin material, selecting a solid silicone resin containing phenyl functional groups as the main base material, endowing the material with excellent oxidation stability, thermal stability, weather resistance, and electrical insulation. Simultaneously, utilizing its glassy state below the melting point, combined with vulcanized cross-linked silicone rubber, it achieves shape memory function after expansion and cooling, and shrinkage function when heated above its melting point. The addition-cure silicone rubber imparts good mechanical and soft properties to the material. Platinum flame retardant, in conjunction with a small amount of aluminum hydroxide flame retardant, imparts good flame retardant properties. To satisfy the shape memory function of the material, a two-component platinum catalyst is added, causing the silicone molecular chains of the addition-cure vulcanized silicone rubber to undergo thermal cross-linking at room temperature / high temperature. While achieving good compatibility, phenyl polyester silicone wax improves the processing performance of the material, facilitating the thorough and uniform mixing of all components.

[0040] 2. The elastic silicone resin heat shrink tubing prepared by this invention has good flame retardancy, high tear strength, low hardness, resistance to bending fatigue, and resistance to harsh environments such as high temperature and low temperature. It can be applied to electric drive vehicles, electronics industry and other scenarios for bending fatigue and high and low temperature insulation protection. Detailed Implementation

[0041] To make the technical means, creative features, achieved objectives, and effects of this invention readily understandable, the invention is further illustrated below with specific embodiments. However, these embodiments are merely preferred embodiments and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the scope of protection of this invention. It is worth noting that the raw materials used in this invention are all common commercially available products, and their sources are not specifically limited. The technical and scientific terms used in the embodiments have the meanings commonly understood by those skilled in the art to which this invention pertains.

[0042] The raw materials described in this application:

[0043] The solid silicone resin containing phenyl functional groups is a white solid. The preferred raw material is solid phenyl silicone resin, model SIC-6168P, produced by Guangzhou Carbon Silicon New Materials Co., Ltd.

[0044] The addition-cured silicone rubber is a semi-transparent colloid. Its main characteristic is its two-stage tensile strength (tested under the conditions of A / B (0.5 / 0.7) after 2h vulcanization at 200℃, typical tensile strength ≥9MPa, typical elongation at break ≥800%, tear strength ≥30kN / m). The preferred raw material is addition-cured silicone rubber from Xin'an Tianyu Organosilicon Co., Ltd., model TY6145-40P.

[0045] The platinum flame retardant is a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex with a PT content of 5000 ppm. The preferred raw material source is PT-5000FR029 (powder) produced by Kejunchi New Materials Co., Ltd.

[0046] Aluminum hydroxide requires a maximum particle size Dmax ≤ 10 μm, and the source of raw materials is not limited.

[0047] Two-component platinum catalyst: A / B vulcanizing agent. Agent A mainly consists of platinum and hydrogen-containing silicone oil, and appears as a transparent gel, acting as a catalyst; Agent B mainly consists of inhibitors and crosslinking agents. The preferred raw materials are HC-100A and HC-100B manufactured by Guilin Yutian New Materials Co., Ltd.

[0048] Example 1

[0049] 100 parts of a solid silicone resin polymer containing phenyl functional groups, 80 parts of addition-curing silicone rubber, 0.1 parts of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex, 10 parts of aluminum hydroxide, 0.5 parts of a two-component platinum catalyst, and 0.5 parts of phenyl polyester silicone wax.

[0050] The preparation method of the elastic silicone sleeve with shape memory function includes the following steps S1-S5:

[0051] S1. Heated Vacuum Kneading and Mixing: Solid silicone resin polymer containing phenyl functional groups, addition-cured silicone rubber, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex, aluminum hydroxide, and phenyl polyester silicone wax are added to a type M double-wrist kneader. The kneader is heated to 105℃, and the kneading speed is within the range of 40 rpm for 30 minutes, until the solid silicone resin is completely melted and uniformly mixed with the addition-cured silicone rubber. Then, the vacuum device is turned on, and the vacuum degree is set to -0.06 MPa and maintained for 2 minutes to obtain premixed polymer A. At this point, because the solid silicone resin forms a continuous phase after melting, while the addition-cured silicone rubber exhibits a discontinuous phase, premixed polymer A will become brittle after cooling at room temperature.

[0052] S2. Then, it is completely cooled to 20°C and added to a two-roll mill for refining. The specific refining conditions are: two-roll temperature set to 20°C, two-roll gap of 20mm, refining 20 times; two-roll gap of 1mm, refining 3 times; finally, it is sheeted at 25mm. This makes the addition-cured silicone rubber component present as a continuous phase again, and the material is in a rubbery state. Then, a two-component platinum catalyst is added in proportion for secondary refining. The specific conditions for secondary refining are: two-roll temperature set to 25°C, two-roll gap of 10mm, refining 20 times; two-roll gap of 1mm, refining 3 times; finally, it is sheeted at 30mm. Compound B for preparing elastic silicone resin sleeves with shape memory function is obtained.

[0053] S3. Rubber compound B is extruded at room temperature using a silicone extruder, and then molded into a tubular preform. It is then subjected to thermosetting vulcanization crosslinking in a high-temperature vulcanizing furnace at 500°C, and further thermosetting crosslinking in a high-temperature vulcanizing tank at 250°C to obtain the crosslinked preform C.

[0054] S4 heats and softens the tube blank C to 160°C, then expands it to 1.5 times its original size using an expansion machine and expansion mold, and cools and shapes it with cold water below 20°C to obtain an elastic silicone sleeve with shape memory function.

[0055] Example 2

[0056] 100 parts of a functional group-containing solid silicone resin polymer, 100 parts of addition-curing silicone rubber, 0.2 parts of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex, 20 parts of aluminum hydroxide, 0.5 parts of a two-component platinum catalyst, and 1 part of phenyl polyester silicone wax.

[0057] The difference between steps S1-S5 and those in Example 1 is as follows:

[0058] In S1, the difference is that the kneader temperature is set to 100℃, the kneader speed is set to 50 Rpm, the kneading time is 35 min, the vacuum degree is set to -0.08 MPa, and the vacuuming time is set to 5 min.

[0059] The process conditions for steps S2-S3 are the same. In step S4, the tube blank C is heated and softened to 180°C, and then expanded to twice its original size using an expander and an expander mold. All other operations are the same.

[0060] Example 3

[0061] 100 parts of a functional group-containing solid silicone resin polymer, 120 parts of addition-curing silicone rubber, 0.3 parts of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex, 30 parts of aluminum hydroxide, 0.8 parts of a two-component platinum catalyst, and 2 parts of phenyl polyester silicone wax.

[0062] The difference between steps S1-S5 and those in Example 1 is as follows:

[0063] In S1, the difference is that the kneader temperature is set to 110℃, the kneader speed is set to 30 Rpm, the kneading time is 38 min, the vacuum degree is set to -1 MPa, and the vacuuming time is set to 1 min.

[0064] The process conditions for steps S2 and S3 are the same. In step S4, the tube blank C is heated and softened at 200°C and then expanded to its 3-fold size using an expander and an expander mold. All other operations are the same.

[0065] Comparative Example 1

[0066] Compared to Example 1, the only difference was that the addition-curing silicone rubber was replaced with a general-purpose precipitated silicone rubber with a hardness of 40A. The half-moon tear strength was 8 kN / m. All other operations remained the same.

[0067] Comparative Example 2

[0068] The difference from Example 1 is that no platinum flame retardant was added. All other operations are the same.

[0069] Comparative Example 3

[0070] Compared to Example 1, the only difference was that the addition-curing silicone rubber was replaced with a general-purpose fumed silicone rubber with a hardness of 48A and a half-moon tear strength of 14 kN / m. All other operations remained the same.

[0071] Comparative Example 4

[0072] Compared to Example 1, only the proportions of each component were changed, as follows:

[0073] The mixture consists of 80 parts of a functionalized solid silicone polymer, 130 parts of an addition-curing silicone rubber, 0.5 parts of a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex, 40 parts of aluminum hydroxide, 1.5 parts of a two-component platinum catalyst, and 3 parts of phenyl polyester silicone wax. All other procedures are the same.

[0074] Comparative Example 5

[0075] Compared to Example 1, the only difference was that the functionalized solid silicone polymer was replaced with a liquid phenyl silicone resin. All other operations remained the same.

[0076] Comparative Example 6

[0077] Compared to Example 1, the phenyl silicone resin was replaced with an equal amount of LDPE. All other operations remained the same.

[0078] Comparative Example 7

[0079] Compared to Example 1, the phenyl silicone resin was replaced with an equal amount of EVA. All other operations remained the same.

[0080] Comparative Example 8

[0081] Compared to Example 1, the phenyl polyester silicone wax was removed. All other operations remained the same.

[0082] The casing performance test results obtained according to the casing preparation methods of Examples 1-3 and Comparative Examples 1-8 are shown in Table 1-2 below:

[0083] Table 1. Performance test results of the sample in the example

[0084]

[0085]

[0086] Table 2. Performance test results of comparative samples

[0087]

[0088]

[0089]

[0090] As shown in Table 1-2: Comparative Example 1 uses precipitated silicone rubber, and Comparative Example 3 has low tear strength, resulting in substandard flexural fatigue and tear strength. Comparative Example 2 does not add platinum flame retardant, only aluminum hydroxide flame retardant, and the material cannot meet the V0 flame retardant requirement. Comparative Example 4 has low phenyl silicone resin content, excessively high silicone rubber content, and excessively high flame retardant content, resulting in substandard flexural fatigue and tear strength. Comparative Example 5 uses liquid phenyl silicone resin, and its low-temperature bending resistance, flame retardancy, and tear strength are all substandard. Furthermore, the material lacks low-temperature curing capability after expansion and cannot be fully expanded and shaped. Comparative Example 6 uses LDPE instead of solid phenyl silicone resin, and the material's heat aging resistance and other properties are significantly reduced and substandard. Comparative Example 7 uses EVA instead of solid phenyl silicone resin, and the material's heat aging resistance and other properties are significantly reduced and substandard. Comparative Example 8 does not add phenyl polyester silicone wax, resulting in reduced compatibility of the components in the system and substandard flexural fatigue resistance.

[0091] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A flexible silicone resin sleeve with shape memory function, characterized in that, The material is made from elastic silicone resin. The elastic silicone resin comprises, by weight, the following components: 90-110 parts of a solid silicone resin polymer containing phenyl functional groups, 75-125 parts of silicone rubber, 9-35 parts of a composite flame retardant, 0.4-1 parts of a catalyst, and 0.3-2.5 parts of phenyl polyester silicone wax. The silicone rubber is an addition-curing type silicone rubber. The composite flame retardant is a combination of platinum flame retardant and aluminum hydroxide in a weight ratio of 1:90-110. The addition-curing silicone rubber is an addition-curing silicone rubber from Xin'an Tianyu Organosilicon Co., Ltd., model TY6145-40P. The catalyst is a two-component platinum catalyst produced by Guilin Yutian New Materials Co., Ltd., models HC-100A and HC-100B. The method for preparing the elastic silicone resin sleeve includes the following steps: S1: A solid silicone resin polymer containing phenyl functional groups, silicone rubber, composite flame retardant, and phenyl polyester silicone wax are heated and kneaded under vacuum to obtain premixed polymer A. S2: Premixed polymer A is cooled to ≤30℃, refined, and then a two-component platinum catalyst is added for secondary refining to obtain rubber compound B; S3: Rubber compound B is extruded at a temperature ≤30℃, and formed into a tubular preform through a mold. It is then thermosetting and vulcanizing at 500-650℃, and further thermocrosslinked at 200-380℃ to obtain preform C. S4: Heat and soften the tube blank C at 130-280℃, expand it to 1-3 times its original size, and cool and shape it at 0-22℃ to obtain an elastic silicone sleeve with shape memory function.

2. The elastic silicone resin sleeve according to claim 1, characterized in that, The platinum flame retardant is a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex with a PT content of 5000 ppm.

3. The elastic silicone resin sleeve according to claim 1, characterized in that, The melting temperature of the phenyl polyester silicone wax is 50-70℃.

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