Vulcanized silicone rubber for connecting steel bars and processing method thereof

Abstract

The invention relates to vulcanized silicone rubber for connecting steel bars and a processing method thereof, and belongs to the technical field of high-performance organic silicon materials and metal-macromolecule composite processing, the vulcanized silicone rubber comprises the following raw materials: a basic polymer, a reinforcing filler, a self-adhesive high-resilience modifier, a cross-linking agent, a catalyst, an inhibitor and a lightweight component, according to the scheme, high-viscosity vinyl-terminated polydimethylsiloxane is adopted as a basic polymer, and a low-filler and low-crosslinking design strategy is matched, so that the hardness of a product can be reduced to Shore A21 degrees to 29 degrees, and the 100% modulus at definite elongation M100 is remarkably reduced; meanwhile, long-chain alkyl in the modifier plays a key internal plasticizing role, so that the crystallization trend of the polymer is effectively destroyed, and the hysteresis feeling of traditional soft rubber is avoided while the extremely soft touch feeling of the material is kept.

Description

Technical Field

[0001] This invention relates to the field of high-performance organosilicon materials and metal-polymer composite processing, specifically to a vulcanized silicone rubber for connecting steel bars and its processing method. Background Technology

[0002] Currently, in the fields of garment manufacturing and industrial component connections, especially in the production of intimate apparel such as bra underwires, the composite connection between steel strips and elastomers primarily relies on silicone rubber. To ensure wearing comfort, the silicone rubber covering or connecting the steel strip is typically required to have low hardness and good elasticity to mimic the feel of human skin. Simultaneously, because the steel strip is subjected to frequent bending and tensile stresses during wear, the silicone rubber and metal interface must possess extremely high adhesive strength to prevent the adhesive layer from detaching or delaminating.

[0003] However, the relevant technologies have obvious shortcomings in achieving a balance between the ultimate soft touch and highly reliable adhesion. Existing low-hardness silicone rubber solutions usually achieve softness by reducing the amount of crosslinking agent or lowering the crosslinking density, but this often leads to severe memory rebound phenomenon in the material, i.e., a significant lag. In this state, after the silicone rubber is subjected to external pressure or deforms with body movement, the deformation recovery is extremely slow, as if it has a memory of the deformed state, lacking an immediate dynamic rebound response. This memory rebound means that the material cannot rebound and fit synchronously when the wearer moves their limbs, resulting in insufficient support and an uncomfortable dragging feeling.

[0004] In addition, existing technologies often add small molecule thickeners such as silane coupling agents to improve adhesion to metals; however, in practical applications, these small molecule substances are prone to forming high-density rigid cross-linked networks in local areas, which leads to a significant increase in the hardness of the vulcanized products, causing the materials to lose their original flexibility and become stiff, further exacerbating the contradiction between tactile feel and functionality.

[0005] Meanwhile, existing technologies often face the contradiction of negative correlation between bond strength and material modulus when dealing with metal interface bonding. When attempting to obtain a low modulus feel by reducing filler content or reducing crosslinking agent dosage, the cohesive strength and interface anchoring ability of the material will decrease, resulting in frequent interface detachment in peel tests and failure to achieve stable cohesive failure.

[0006] For certain special applications, silicone rubber products made with existing technology have a high density, which increases the overall weight burden during prolonged wear or use and lacks a light and supportive feel. Therefore, how to eliminate the memory rebound lag and achieve rapid dynamic response while taking into account low hardness, lightweight and high adhesion is a technical challenge that urgently needs to be improved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a vulcanized silicone rubber for connecting steel bars and a processing method thereof, so as to solve the problems mentioned in the background art.

[0008] The technical solution of the present invention includes the following raw materials: base polymer, reinforcing filler, self-adhesive high resilience modifier, crosslinking agent, catalyst, inhibitor and lightweight component; The base polymer is vinyl-terminated polydimethylsiloxane, the reinforcing filler is hydrophobically treated fumed silica, the self-adhesive high-resilience modifier is a polysiloxane oligomer grafted with multifunctional side chains, the crosslinking agent is a platinum complex, the catalyst is a alkynyl alcohol compound, and the lightweight component is hollow microspheres with a surface treated with a vinylsilane coupling agent.

[0009] Preferably, the raw materials, by weight, are: 100 parts of base polymer, 20-40 parts of reinforcing filler, 2-8 parts of self-adhesive high-resilience modifier, 1-5 parts of crosslinking agent, 0.05-0.2 parts of catalyst, 0.01-0.1 parts of inhibitor, and 0.1-5 parts of lightweight component.

[0010] Preferably, the viscosity of the base polymer at 25°C is 10,000~100,000 mPa·s; The specific surface area of ​​the reinforcing filler is 200~300m². 2 / g and the surface is grafted with trimethylsilyl groups; The side chains of the self-adhesive high-resilience modifier are simultaneously grafted with epoxy groups, C8 to C12 alkyl chains, and vinyl groups; The hydrogen content of the crosslinking agent is 0.5–1.5 wt%. The catalyst is a Karstedt catalyst with a platinum content of 2000-5000 ppm.

[0011] A method for processing vulcanized silicone rubber for connecting steel bars, the method comprising the following steps: (1) Preparation of self-adhesive high-resilience modifier: In a reactor equipped with a reflux condenser, thermometer, and dropping funnel, add 100 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.8 wt% and 80-120 parts by weight of toluene solvent, start stirring and heat to 80°C, add platinum catalyst at 10-30 ppm relative to the mass of hydrogen-containing silicone oil; maintain the temperature, dropwise add a mixture of allyl glycidyl ether and 1-dodecene, wherein the molar ratio of allyl glycidyl ether to 1-dodecene in the mixture is 1:0.8-1.2, and the total amount of the mixture added is based on the molar ratio of Si-H bonds to C=C double bonds. A hydrosilylation reaction was carried out using a ratio of 1:0.5 to 0.7. After the addition was complete, the mixture was refluxed at 80°C for 4 hours until the characteristic Si-H peaks in the infrared spectrum disappeared. Subsequently, 5-10% by weight of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and 0.1-0.5% by weight of a strong acid cation exchange resin were added, and an equilibrium end-capping reaction was carried out at 80-100°C. After the reaction was completed, the temperature was raised to 110°C and vacuum distillation was performed to remove toluene solvent and low-boiling substances, yielding the self-adhesive high-resilience modifier as a pale yellow transparent liquid. (2) Preparation of base glue: The base polymer and reinforcing filler in the specified weight parts are put into a vacuum kneader, hexamethyldisilazane is added as a structure control agent, the temperature is raised to 120°C, and vacuum kneading is carried out for 2 hours under a vacuum gauge pressure of −0.09MPa to destroy the filler agglomerates and remove volatiles. After cooling, the base glue is obtained. (3) Mixing and degassing: The base rubber obtained in step (2) is transferred to a planetary mixer, and the self-adhesive high-resilience modifier, crosslinking agent, lightweight component and inhibitor prepared in step (1) are added in sequence. The mixture is dispersed at high speed for 30 minutes at room temperature. Then the catalyst is added, the stirring speed is adjusted to low speed, and the vacuum system is turned on for static degassing treatment for 15 minutes to obtain a two-component liquid silicone rubber composition. (4) Integrated injection molding vulcanization: The steel strip that has been cleaned and degreased by solvent is placed into the mold cavity. After the mold is closed, the liquid silicone rubber composition obtained in step (3) is injected into the mold. The mold temperature is set to 160°C and the pressure is maintained for vulcanization for 60 to 120 seconds. During this process, the epoxy groups in the self-adhesive high-resilience modifier open the ring and form chemical bonds with the surface of the steel strip. The long-chain alkyl groups construct flexible micro-regions, and the vinyl groups participate in the cross-linking network. After the mold is opened, the vulcanized silicone rubber product with the steel strip is obtained.

[0012] Preferably, the lightweight component is hollow glass microspheres or polymer microspheres with a density of less than 0.3 g / cm³. 3 The inhibitor is 1-ethynyl-1-cyclohexanol.

[0013] Preferably, the vulcanized silicone rubber, after complete curing, has a Shore A hardness of 20–30, a resilience greater than 65%, and a system density between 0.85 and 0.95 g / cm³. 3 between.

[0014] Preferably, the vulcanized silicone rubber forms a primer-free chemical bonding interface with the steel strip, its 180° peel strength is greater than 4.0 N / mm, and the peel interface failure mode is 100% cohesive failure.

[0015] Preferably, after the mold is opened in step (4), the method further includes a step of performing a two-stage vulcanization treatment on the product; the conditions for the two-stage vulcanization treatment are baking at 200°C for 2 hours to eliminate low molecular weight residues and further improve the resilience of the material.

[0016] This invention provides an improved method for processing vulcanized silicone rubber for connecting steel bars, which, compared with the prior art, has the following improvements and advantages: 1. Due to the use of high-viscosity vinyl-terminated polydimethylsiloxane as the base polymer in this solution, combined with a low-filler and low-crosslinking design strategy, the hardness of the product can be reduced to Shore A 21 to 29 degrees, and the 100% tensile modulus M100 is significantly reduced. At the same time, the long-chain alkyl groups in the modifier play a key internal plasticizing role, effectively disrupting the crystallization tendency of the polymer, so that the material maintains an extremely soft touch while avoiding the lag of traditional soft rubber. 2. The epoxy groups of the self-adhesive high-resilience modifier side chain in this solution can form strong covalent bonds with the metal oxide layer on the surface of the steel strip at high temperature. Experimental data show that the peel strength can reach up to 5.5 N / mm, and the failure mode is 100% cohesive failure. This shows that this solution can construct a chemical bonded layer with a strength higher than that of the colloid without the need to apply a primer, thus solving the industry pain point of easy delamination of soft adhesive. 3. By precisely controlling the ratio of catalyst to inhibitor, sufficient time is provided for the migration of modifier molecules to the metal interface; before the adhesive gels, the macromolecular modifier can be fully enriched at the steel strip interface, ensuring effective chemical bonding at the interface. By introducing hollow microspheres with vinyl-modified surfaces, the vinyl groups on the surface of the microspheres participate in the cross-linking reaction, and the microspheres are tightly bonded to the matrix, maintaining excellent mechanical properties while reducing weight, giving the product a lightweight and supportive feel. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. Example 1

[0018] This invention provides a vulcanized silicone rubber for connecting steel bars, comprising the following raw materials: a base polymer, reinforcing filler, a self-adhesive high-resilience modifier, a crosslinking agent, a catalyst, an inhibitor, and a lightweight component; the base polymer is vinyl-terminated polydimethylsiloxane, the reinforcing filler is hydrophobically treated fumed silica, the self-adhesive high-resilience modifier is a polysiloxane oligomer grafted with multifunctional side chains, the crosslinking agent is hydrogen-containing silicone oil with side chains, the catalyst is a platinum complex, the inhibitor is an alkynyl alcohol compound, and the lightweight component is hollow microspheres with a surface treated with a vinyl silane coupling agent; In this embodiment, the base polymer is a vinyl-terminated polydimethylsiloxane with a viscosity of 100,000 mPa·s. This ultra-high viscosity polymer segment provides excellent flexibility and extensibility, which is the basis for constructing a low-modulus tactile feel. The reinforcing filler is selected with a specific surface area of ​​200 m². 2 / g of fumed silica with a surface completely hydrophobically treated with hexamethyldisilazane has a low specific surface area that limits the density of physical crosslinking points, which helps to further reduce the hardness of the rubber compound; the inhibitor is 1-ethynyl-1-cyclohexanol, whose steric hindrance effect can effectively inhibit the activity of platinum catalyst at room temperature, ensuring that the rubber compound has a pot life of up to 24 hours. The raw materials, by weight, are: 100 parts of base polymer, 20 parts of reinforcing filler, 2 parts of self-adhesive high-resilience modifier, 1 part of crosslinking agent, 0.05 parts of catalyst, 0.01 parts of inhibitor, and 0 parts of lightweight component; This embodiment employs a low-filler, low-crosslinking formulation strategy to create an extremely soft tactile experience. The amount of self-adhesive high-resilience modifier added is precisely controlled at 2 parts. This dosage is sufficient to form a monolayer of chemical bonding on the steel strip surface without increasing the system's brittleness due to excessive epoxy group self-polymerization. The crosslinking agent is used in only 1 part, resulting in a larger molecular weight of the vulcanized network chain, giving the material a soft and resilient feel similar to human skin. Furthermore, the extremely low ratio of catalyst (0.05 parts) to inhibitor (0.01 parts) is another key to this formulation. This ratio is not only for the pot life but also to match the diffusion kinetics of the macromolecular modifier. The low-concentration catalytic system provides a longer viscosity ramp-up period, allowing the macromolecular modifier sufficient time to migrate from the bulk to the steel strip interface before gelation. This ensures effective chemical bonding and high adhesion at the interface without sacrificing the bulk's softness and low modulus. The viscosity of the base polymer is 100,000 mPa·s; the specific surface area of ​​the reinforcing filler is 200 m². 2 / g and the surface is grafted with trimethylsilyl groups; the side chains of the self-adhesive high resilience modifier are simultaneously grafted with epoxy groups, C8 to C12 alkyl chains and vinyl groups; the hydrogen content of the crosslinking agent is 0.5wt%; the catalyst is a Karstedt catalyst with a platinum content of 2000ppm. It is worth noting here that the C8-C12 alkyl long-chain alkyl groups branched on the side of the self-adhesive high-resilience modifier, derived from 1-dodecene, play a crucial role in internal plasticization. The long alkyl chains swing freely in the siloxane network, effectively disrupting the polymer's crystallization tendency, allowing the material to maintain excellent flexibility at low temperatures. The crosslinking agent with a hydrogen content of only 0.5wt%, combined with a highly active platinum catalyst, constructs a loose but uniform crosslinking network, avoiding hard spots caused by excessively high local crosslinking density. A method for processing vulcanized silicone rubber for connecting steel bars, the method includes the following steps: (1) preparing a self-adhesive high resilience modifier: in a reaction vessel equipped with a reflux condenser, a thermometer and a dropping funnel, add 100 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.8 wt% and 80 parts by weight of toluene solvent, start stirring and heat to 80°C, and add a platinum catalyst with a mass of 10 ppm relative to the hydrogen-containing silicone oil; While maintaining the temperature, a mixture of allyl glycidyl ether and 1-dodecene was added dropwise. The molar ratio of allyl glycidyl ether to 1-dodecene in the mixture was 1:0.8, and the total amount of the mixture added was calculated based on a molar ratio of Si-H bonds to C=C double bonds of 1:0.5. A hydrosilylation reaction was carried out. After the addition was complete, the mixture was refluxed at 80°C for 4 hours until the characteristic peak of Si-H in the infrared spectrum disappeared. Subsequently, 5% by weight of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane containing hydrosilicone oil was added to carry out an equilibrium end-capping reaction. After the reaction was completed, the temperature was raised to 110°C and vacuum distillation was performed to remove toluene solvent and low-boiling substances, yielding a pale yellow transparent liquid self-adhesive high-resilience modifier. The 1,3-divinyl-1,1,3,3-tetramethyldisiloxane used in this step is specifically 1,3-divinyl-1,1,3,3-tetramethyldisiloxane as a capping agent. This substance ensures that both ends of the modifier molecule are capped with highly active vinyl groups, thereby guaranteeing its access to the vulcanization network. In this step, the molar ratio of Si-H bonds to C=C double bonds is strictly controlled at 1:0.5, which means that about 50% of the active Si-H bonds are retained for subsequent vinyl capping and the final vulcanization reaction. Specifically, the molar ratio of allyl glycidyl ether to 1-dodecene was set to 1:0.8, a key process parameter determined based on the aforementioned model. AFM testing confirmed that at this grafting ratio, the steric hindrance effect of the long-chain alkyl group effectively regulated the aggregation behavior of the polar epoxy group, inducing the formation of soft segment microregions with an average diameter of approximately 90 nm, while the hard segment clusters exhibited an ideal dispersed point distribution, thus achieving the optimal match between low modulus and high interfacial anchoring energy as predicted by the model. The lean-oil feeding method used during the dropwise addition process effectively suppressed competing side reactions, ensuring a statistically random distribution of epoxy groups and long-chain alkyl groups on the siloxane backbone. This distribution pattern is beneficial to the compatibility and migration rate of the modifier molecules in the base adhesive. Preparation of base adhesive: The base polymer and reinforcing filler in parts by weight are put into a vacuum kneader, and hexamethyldisilazane is added as a structure control agent. The temperature is raised to 120°C, and vacuum kneading is carried out for 2 hours under a vacuum degree of −0.09MPa to destroy the filler agglomerates and remove volatiles. After cooling, the base adhesive is obtained. The high temperature and negative pressure environment during the vacuum kneading process promotes the in-situ end-capping reaction between hexamethyldisilazane and the residual silanol groups on the surface of fumed silica. In this embodiment, the kneading temperature is precisely controlled at 120℃, with a process allowable range of 115~125℃, and the vacuum degree is maintained at −0.09MPa, with an allowable range of −0.08~−0.095MPa. Experiments have shown that if the temperature is below 115℃, the hydrophobic modification is incomplete, leading to thickening of the adhesive. If the temperature is above 125℃, the risk of polymer thermal degradation increases. 120℃ was chosen as the implementation value because this point is located in the optimal balance zone between reaction efficiency and side reaction control, which can maximize batch-to-batch stability. This process not only eliminates the hydrophilicity of the filler surface and prevents the structural effect during adhesive storage, but also significantly reduces the friction coefficient between the filler and the polymer, further improving the fluidity of the adhesive. Mixing and degassing: The base rubber obtained in step (2) is transferred to a planetary mixer, and the self-adhesive high-resilience modifier, crosslinking agent, lightweight component and inhibitor prepared in step (1) are added in sequence. The mixture is dispersed at high speed for 30 minutes at room temperature. Then the catalyst is added, the stirring speed is adjusted to low speed, and the vacuum system is turned on for static degassing treatment for 15 minutes to obtain a two-component liquid silicone rubber composition. The process sequence of adding catalysts after mixing is adopted to minimize local pre-vulcanization caused by frictional heat. In this step, the low-speed stirring speed is set at 80 rpm, which can effectively prevent the introduction of new air bubbles. For the high viscosity of 100,000 mPa·s, 80 rpm provides the optimal shear / cycle ratio, which ensures degassing efficiency and avoids causing the rubber compound temperature to rise and consume inhibitors. The high-speed dispersion of 30 minutes is set to ensure the uniform dispersion of fillers and modifiers, while the static degassing of 15 minutes is the optimal time calculated based on the bubble rising rate. Too short a time will result in incomplete degassing, while too long a time will affect the production cycle. The static degassing step uses pressure difference to drive the microbubble rupture, ensuring the density and optical transparency of the final vulcanized product. Integrated injection molding vulcanization: The steel strip that has been solvent-cleaned and degreased is placed into the mold cavity. After the mold is closed, the liquid silicone rubber composition obtained in step (3) is injected into the mold. The mold temperature is set to 160°C and the pressure is maintained for 60 seconds. During this process, the epoxy groups in the self-adhesive high-resilience modifier open the ring and form chemical bonds with the surface of the steel strip. The long-chain alkyl groups construct flexible micro-regions, and the vinyl groups participate in the cross-linking network. After the mold is opened, the vulcanized silicone rubber product with the steel strip is obtained. During the injection molding vulcanization stage, the high temperature of 160℃ instantly activates the platinum catalyst, triggering a rapid addition reaction between vinyl groups and Si-H bonds. At the same time, the modifier molecules are enriched at the high surface energy metal interface under the drive of the thermal gradient. The epoxy groups open at high temperature and form a strong CO-Metal covalent bond with the metal oxide layer on the surface of the steel strip, achieving second-level chemical anchoring. The product prepared in this embodiment exhibits extremely low hardness, close to Shore A21, due to the large molecular weight of the base polymer and the small amount of filler. It has an extremely soft feel, and the introduction of the self-adhesive high-resilience modifier ensures that it can still maintain effective adhesion to the steel strip under low crosslinking density, perfectly solving the industry pain point of easy delamination of soft glue. Example 2

[0019] A type of vulcanized silicone rubber for connecting steel bars comprises the following raw materials: a base polymer, reinforcing filler, a self-adhesive high-resilience modifier, a crosslinking agent, a catalyst, an inhibitor, and a lightweight component; the raw materials, by weight, are: 100 parts base polymer, 30 parts reinforcing filler, 5 parts self-adhesive high-resilience modifier, 3 parts crosslinking agent, 0.1 parts catalyst, 0.05 parts inhibitor, and 0 parts lightweight component; This embodiment aims to verify the overall performance balance under medium viscosity and medium filler dosage. The base polymer viscosity is set to 50000 mPa·s, which takes into account both mechanical strength and flowability during injection molding. The specific surface area of ​​the reinforcing filler is 250 m² / g, and the moderate reinforcing effect provides the necessary tear resistance. In this formulation, the amounts of catalyst (0.1 parts) and inhibitor (0.05 parts) are increased compared to Example 1. This is not only to accommodate the diffusion resistance caused by the increased filler, but also to control the vulcanization depth. The increased amount of inhibitor precisely offsets the additional heat history generated by filler friction, preventing early cross-linking and scorching of the rubber compound during the injection molding stage. This ensures that the epoxy groups in the modifier can completely wet the micropores of the steel strip before curing, thereby ensuring the stability of the peel strength. The side chains of the self-adhesive high-resilience modifier are simultaneously grafted with epoxy groups, C8-C12 alkyl long-chain alkyl groups, and vinyl groups; the hydrogen content of the crosslinking agent is 1.0 wt%; the catalyst is a Karstedt catalyst with a platinum content of 3500 ppm. In the modifier synthesis step, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane was used; the molar ratio of allyl glycidyl ether to 1-dodecene in the mixture was adjusted to 1:1.0, and the total amount added was calculated based on a molar ratio of Si-H bond to C=C double bond of 1:0.6. This adjustment of the ratio made the distribution of polar epoxy groups and non-polar long-chain alkyl groups on the side chain of the modifier more balanced. According to the aforementioned mechanism model, this ratio precisely controlled the microphase separation scale of the soft segment to about 75 nm. At this scale, the point distribution density of the hard segment clusters increased but no aggregation occurred, which not only ensured the wettability with the metal interface, but also effectively improved the resilience of the material through the steric hindrance effect of the long-chain alkyl groups, verifying the correspondence between the phase separation scale and the balance of comprehensive performance in the model. In the processing method, the low-speed stirring speed in step (3) is specifically set to 80 rpm to match the fluidity of the isoviscosity system in this embodiment. For medium viscosity rubber with a viscosity of 50,000 mPa·s, this speed can produce the best folding-stretching mixing effect. Experimental comparison shows that this speed setting not only ensures the uniformity of mixing but also avoids the introduction of microbubbles, thereby ensuring the optical transparency of the cured colloid. The holding pressure vulcanization time in step (4) is set to 90 seconds. The appropriate vulcanization time allows the modifier molecules to fully migrate to the metal interface and undergo ring-opening reaction to form a dense chemical bond layer. The product obtained in this embodiment exhibits excellent comprehensive performance, moderate hardness (approximately Shore A25), significant resilience, and high peel strength with steel strips, making it suitable for the connection requirements of most standard bra underwires.

[0020] Example 3

[0021] A type of vulcanized silicone rubber for connecting steel bars comprises the following raw materials: a base polymer, reinforcing filler, a self-adhesive high-resilience modifier, a crosslinking agent, a catalyst, an inhibitor, and a lightweight component; the raw materials, by weight, are: 100 parts base polymer, 40 parts reinforcing filler, 8 parts self-adhesive high-resilience modifier, 5 parts crosslinking agent, 0.2 parts catalyst, 0.1 parts inhibitor, and 0 parts lightweight component; This embodiment is designed for scenarios requiring high strength and high adhesion. The viscosity of the base polymer is set to 100,000 mPa·s. The low viscosity of the base adhesive is beneficial for high filler content and dispersion of 40 parts of filler. The specific surface area of ​​the reinforcing filler is 300 m². 2 / g, the high specific surface area provides strong physical cross-linking points, significantly improving the tensile strength of the material; the high dosage of catalyst (0.2 parts) and inhibitor (0.1 parts) is to cope with the quenching effect of free radicals and the thermal effect of high shear mixing in the high filler system; the 0.1 parts inhibitor ensures that no scorching occurs during the strong shearing process of the high thixotropic rubber, while the 0.2 parts catalyst ensures that a high-density cross-linking network can be established instantly during the vulcanization stage, which is crucial for achieving high peel strength of 5.5 N / mm under high modulus while maintaining high resilience (66%); The crosslinking agent has a hydrogen content of 1.5 wt%; the catalyst is a Karstedt catalyst with a platinum content of 5000 ppm. A dense cross-linked network was constructed using 1.5 wt% of a high-volume cross-linking agent (5 parts). In the synthesis of the modifier, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane was used as the 1,3-divinyl-1,1,3,3-tetramethyldisiloxane to ensure end-group activity. The molar ratio of allyl glycidyl ether to 1-dodecene in the mixture was adjusted to 1:1.2, and the total amount added was calculated based on a Si-H bond to C=C double bond molar ratio of 1:0.7. This specific functional group molar ratio aims to compress the diameter of the soft segment microregion to the lower limit defined by the model, approximately 55 nm. Under this microstructure, the number of hard segment anchor points per unit volume reaches its peak and remains dispersed, thereby maximizing the chemical bonding density at the interface to resist the interfacial shear stress caused by the high modulus. The measured results are in complete agreement with the high-strength range predicted by the model. In the processing method, the low-speed stirring speed in step (3) is adjusted to 100 rpm to provide sufficient shear force to mix the high-filler rubber compound while avoiding air bubble entrainment. Choosing 100 rpm is necessary because for the high thixotropic rubber compound formed by low viscosity base rubber and high filler content, sufficient shear rate must be applied to overcome the yield value and achieve effective flow. If the speed is insufficient, the rubber compound will not be able to form effective convection, resulting in incomplete degassing. The holding pressure vulcanization time in step (4) is set to 120 seconds. The extended vulcanization time ensures that heat can be fully transferred to the interface in the dense filler network, so that the high concentration of epoxy groups can react completely. Although the hardness of the product obtained in this embodiment is slightly improved, close to Shore A29, it has obtained the highest peel strength and tear resistance. Moreover, due to the plasticizing effect of long-chain alkyl in the modifier, the material still maintains a good dynamic rebound rate under high hardness, avoiding a stiff feeling. Example 4

[0022] A type of vulcanized silicone rubber for connecting steel bars comprises the following raw materials: a base polymer, reinforcing filler, a self-adhesive high-resilience modifier, a crosslinking agent, a catalyst, an inhibitor, and a lightweight component; the raw materials, by weight, are: 100 parts base polymer, 25 parts reinforcing filler, 4 parts self-adhesive high-resilience modifier, 2 parts crosslinking agent, 0.1 parts catalyst, 0.05 parts inhibitor, and 5 parts lightweight component; This embodiment introduces lightweight components to verify low-density properties; the base polymer viscosity is 50000 mPa·s. The lightweight component is hollow glass microspheres with a density of less than 0.3 g / cm³. 3 The inhibitor is 1-ethynyl-1-cyclohexanol. The lightweight component is specifically selected with a particle size of 20-50 μm and a density of 0.25 g / cm³. 3 The surface of the hollow glass microspheres is modified with vinyl esters. The addition of hollow microspheres significantly reduces the system density by utilizing the principle of physical site occupancy, and the vinyl esters on their surface can participate in the vulcanization reaction, ensuring that the microspheres are firmly bonded to the matrix and that no debeading occurs; The processing method is basically the same as in Example 2, but in step (3) during mixing, the high-speed dispersion needs to be adjusted to low-speed stirring, for example, the rotation speed should be less than 200 rpm, to prevent the hollow microspheres from breaking; the system density of the product obtained in this example is reduced to 0.88 g / cm³. 3 It is significantly lower than that of conventional silicone rubber; this low density characteristic, combined with the material's high resilience, gives the steel ring connection a light and supportive feel similar to floating feathers, greatly improving the user's wearing comfort. Example 5

[0023] A type of vulcanized silicone rubber for connecting steel bars, the raw materials by weight are: 100 parts of base polymer, 35 parts of reinforcing filler, 6 parts of self-adhesive high-resilience modifier, 4 parts of crosslinking agent, 0.15 parts of catalyst, 0.08 parts of inhibitor, and 2 parts of lightweight component. This embodiment aims to verify the interface failure mode when different ratios of modifiers are combined with medium to high viscosity base adhesives; the viscosity of the base polymer is 80000 mPa·s, and the lightweight component is polymer microspheres; The side chains of the self-adhesive high-resilience modifier are simultaneously grafted with epoxy groups, C8 long-chain alkyl groups, and vinyl groups; here, C8 alkyl chains are selected, and 1-octene is used instead of C8-C12 alkyl chains to test the effect of shorter alkyl chains on the fine-tuning of modulus and resilience; shorter alkyl chains provide slightly higher rigidity, which helps to maintain the dimensional stability of the material under higher filler loads. After the mold is opened in step (4), the method also includes a step of performing a two-stage vulcanization treatment on the product; the conditions for the two-stage vulcanization treatment are to bake at 200°C for 2 hours to eliminate low molecular weight residues and further improve the resilience of the material. The two-stage vulcanization step is crucial. It not only removes reaction byproducts but also promotes further cross-linking of residual epoxy groups in the modifier, strengthening the interfacial bonding. The product prepared in this embodiment exhibits a stable 100% cohesive failure mode in the peel force test, that is, the adhesive layer breaks rather than the interface separates. This indicates that the self-adhesive high-resilience modifier has successfully constructed a chemically bonded layer on the steel strip surface with a strength higher than that of the adhesive itself, fully meeting the high standard requirement of no primer.

[0024] Comparative Example 1: This comparative example aims to illustrate the effect of not adding the self-adhesive high-resilience modifier. The self-adhesive high-resilience modifier was completely removed from the formulation, and the remaining components and amounts were strictly consistent with those in Example 2, including 100 parts of base polymer, 30 parts of reinforcing filler, and 3 parts of crosslinking agent. The processing technology was the same as in Example 2. This comparative example serves as a blank control to verify the decisive role of the modifier in achieving metal bonding.

[0025] Comparative Example 2: This comparative example aims to illustrate the difference between using a commercially available common silane coupling agent instead of the modifier of this invention. In this formulation, 2.0 parts of γ-glycidyl etheroxypropyltrimethoxysilane were used instead of the 5 parts of the self-adhesive high-resilience modifier in Example 2; the rest were the same as in Example 2. KH-560 is an industry-standard tackifier. This comparative example is used to verify the advantages of the macromolecular modifier synthesized in this invention over the small-molecule coupling agent in terms of tactile retention and resilience.

[0026] Comparative Example 3:

[0027] This comparative example aims to illustrate the effect of the lack of long-chain alkyl structures in the self-adhesive modifier. In step (1) of preparing the self-adhesive high-resilience modifier, only allyl glycidyl ether was added dropwise, without adding 1-dodecene. The remaining synthesis steps and the vulcanized silicone rubber formulation were the same as in Example 2. This comparative example is used to reveal the key mechanism of long-chain alkyl in constructing the soft and hard segment microphase separation structure and imparting a flexible feel to the material.

[0028] Comparative Example 4: This comparative example aims to illustrate the impact of post-processing on final performance. The formulation is exactly the same as in Example 5, but in the processing method, the two-stage vulcanization treatment in step (5) is omitted, and the vulcanization time in step (4) is shortened to 30 seconds. This comparative example is used to verify the degree of sufficient vulcanization reaction and the necessity of two-stage vulcanization for eliminating low molecular weight residues, stabilizing dimensions and improving resilience.

[0029] Verification experiment: The vulcanized silicone rubber products with connecting steel bars prepared in Examples 1-5 and Comparative Examples 1-4 were tested accordingly, and the test results are shown below: Test method description for physical and mechanical properties and adhesive properties: Hardness: Tested according to ASTM D2240 standard using a Shore A hardness tester, with each sample measured 5 times and the average value taken; Rebound rate: According to GB / T1681 standard, a drop ball rebound tester is used to test and record the percentage of rebound height; Density: determined by the water displacement method according to GB / T533 standard; 180° Peel Strength: The vulcanized sample was subjected to a 180° peel test with a steel strip at a tensile speed of 50 mm / min, and the maximum peel force was recorded. Damage mode: The interface after peeling is observed with the naked eye and under a microscope and recorded as interface failure, where the adhesive layer is completely detached from the surface of the steel strip or cohesive failure occurs, and the adhesive layer itself is torn apart. 100% elongation modulus, M100: Tested according to GB / T528 standard, it characterizes the material's ability to resist deformation. The lower the value, the softer the feel.

[0030] Table 1: Summary of performance test data for Examples 1-5 and Comparative Examples 1-4 The results analysis, as shown in Table 1, demonstrates that Examples 1-5 of this invention successfully resolved the contradiction between low modulus and high adhesion of silicone rubber by introducing a specific self-adhesive high-resilience modifier and coordinating process control. Specifically: Analysis of the toughening and bonding mechanism of the modifier: Compared with Comparative Example 2, the sample using the macromolecular modifier synthesized in this invention has a hardness of 25 degrees that is significantly lower than that of the sample using the small molecule coupling agent KH-560 (35 degrees), and the M100 modulus is reduced by nearly 50%. This is because KH-560, as a small molecule, is prone to forming high-density rigid cross-linking points locally, resulting in hardening of the material and poor resilience (only 50%). In contrast, the modifier of this invention introduces flexible side chains through long-chain alkyl groups, which not only plays an internal plasticizing role but also increases the free volume between molecular chains. Thus, while ensuring adhesion and peel strength of 4.8 N / mm, it maintains excellent resilience (68%) and a soft touch. The key role of long-chain alkyl groups: Compared with Comparative Example 3, after removing the long-chain alkyl group and 1-dodecene, although the peel strength was still high at 4.6 N / mm, the resilience of the material decreased from 68% to 55%, and the M100 modulus increased from 0.62 to 0.095 MPa. This significant difference confirms the hypothesis that long-chain alkyl groups construct soft segment microregions at the microscopic level. Without this structure, the relaxation time of the molecular chain is shortened, resulting in the material exhibiting stronger rigidity and hysteresis loss, and losing its feather-like flexibility. Necessity of process conditions: Compared with Comparative Example 4, the sample without two-stage vulcanization and with insufficient vulcanization time showed a significant decrease in peel strength to 2.8 N / mm, and the failure mode changed to mixed failure. This indicates that the formation of interfacial chemical bonds is a thermally activated process, and sufficient enthalpy input must be ensured to allow the epoxy groups to fully open the ring. At the same time, the lack of two-stage vulcanization resulted in low molecular weight residues, which affected the resilience of the material. Synergistic effect of lightweighting: In Example 4, the density decreased to 0.88 g / cm³ after the introduction of hollow glass microspheres. 3 Furthermore, with the synergistic effect of vinyl modification, no significant degradation in physical and mechanical properties was observed, verifying the feasibility of the lightweight solution. In summary, this invention achieves a comprehensive improvement in the flexibility, resilience, lightweight, and interfacial adhesion reliability of vulcanized silicone rubber for connecting steel bars through a combination of molecular structure design and process optimization.

[0031] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A vulcanized silicone rubber jointed steel bar characterized by: The raw materials include base polymer, reinforcing filler, self-bonding high resilience modifier, crosslinking agent, catalyst, inhibitor and lightweight component; The base polymer is vinyl-terminated polydimethylsiloxane, the reinforcing filler is hydrophobic treated fumed silica, the self-bonding high resilience modifier is side-chain multi-functional group grafted polysiloxane oligomer, the crosslinking agent is side-chain hydrogen-containing silicone oil, the catalyst is platinum complex, the inhibitor is alkyne alcohol compound, and the lightweight component is hollow microsphere treated with vinyl silane coupling agent on the surface.

2. A vulcanized silicone rubber bonded steel cord according to claim 1, characterized in that: The raw materials are as follows in parts by weight: base polymer 100 parts, reinforcing filler 20-40 parts, self-bonding high resilience modifier 2-8 parts, crosslinking agent 1-5 parts, catalyst 0.05-0.2 parts, inhibitor 0.01-0.1 parts, and lightweight component 0.1-5 parts.

3. The vulcanized silicone rubber connecting steel bar according to claim 1, characterized in that: The viscosity of the base polymer at 25℃ is 10000-100000 mPa·s; The reinforcing filler has a specific surface area of 200 to 300 m 2 / g and is surface-grafted with trimethylsilyl groups; The side chain of the self-bonding high resilience modifier is grafted with epoxy group, C8-C12 alkyl chain and vinyl group at the same time; The hydrogen content of the crosslinking agent is 0.5-1.5 wt%; The catalyst is Karstedt catalyst with platinum mass content of 2000-5000 ppm.

4. A process for the manufacture of the vulcanized silicone rubber bonded steel cord as claimed in claim 2, characterized in that: The method comprises the following steps: (1) Preparation of self-adhesive high resilience modifier: in a reaction kettle equipped with a reflux condenser, a thermometer and a dropping funnel, 100 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.8 wt% and 80-120 parts by weight of toluene solvent were added, stirring was started and the temperature was raised to 80°C, 10-30 ppm of platinum catalyst relative to the mass of hydrogen-containing silicone oil was added; the temperature was maintained, and a mixture of allyl glycidyl ether and 1-dodecene was added dropwise, the molar ratio of allyl glycidyl ether to 1-dodecene in the mixture was 1:0.8-1.2, and the total amount of the mixture was calculated according to the molar ratio of Si-H bond to C=C double bond of 1:0.5-0.7, a silicon-hydrogen addition reaction was carried out, after the dropwise addition was completed, refluxing at 80°C for 4 hours until the characteristic peak of Si-H disappeared in the infrared spectrum; the Si-H characteristic absorption peak area at a wave number of 2160 cm −1 was calculated, and the dropwise addition was stopped when the area was 45%-55% of the initial area; then 5-10% of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and 0.1-0.5% of strongly acidic cation exchange resin based on the mass of hydrogen-containing silicone oil were added, and an equilibrium capping reaction was carried out at 80-100°C; after the reaction was completed, the temperature was raised to 110°C and vacuum distillation was carried out with a vacuum system to remove toluene solvent and low-boiling substances, and the self-adhesive high resilience modifier was obtained as a light yellow transparent liquid; (2) Preparation of base glue: the base polymer and reinforcing filler in parts by weight are put into a vacuum kneader, hexamethyldisilazane is added as a structure control agent, the temperature is raised to 120℃, and vacuum kneading is carried out under a vacuum degree of 0.09 MPa gauge pressure for 2 hours to break the agglomerates of the filler and remove volatile components, and the base glue is obtained after cooling; (3) Mixing and degassing: the base glue prepared in step (2) is transferred to a planetary mixer, the self-bonding high resilience modifier, crosslinking agent, lightweight component and inhibitor prepared in step (1) are added in sequence, high-speed dispersion is carried out at room temperature for 30 minutes; then the catalyst is added, the stirring speed is adjusted to low speed, and the vacuum system is opened for static degassing treatment for 15 minutes, during which the vacuum valve is opened and closed quickly every 5 minutes to break the vacuum to accelerate the breaking of deep layer bubbles, and a two-component liquid silicone rubber composition is prepared; (4) Integrated injection vulcanization: the steel bar treated with solvent cleaning and oil removal is placed in the mold cavity, the liquid silicone rubber composition prepared in step (3) is injected into the mold after the mold is closed, the mold temperature is set to 160℃, and pressure vulcanization is carried out for 60-120 seconds; during this process, the epoxy group in the self-bonding high resilience modifier ring opens and forms chemical bonding with the surface of the steel bar, the long-chain alkyl group constructs a flexible microzone, and the vinyl group participates in the crosslinking network, and after the mold is opened, the vulcanized silicone rubber product connecting the steel bar is obtained.

5. A vulcanized silicone rubber bonded steel cord according to claim 1, characterized in that: The lightweight component is hollow glass beads or polymer microspheres with a density of less than 0.3 g / cm 3 ; the inhibitor is 1-ethynyl-1-cyclohexanol.

6. A vulcanized silicone rubber bonded steel cord according to claim 1, characterized in that: The vulcanized silicone rubber has a Shore A hardness of 20-30 degrees after complete curing, a resilience of greater than 65%, and a system density of between 0.85-0.95 g / cm 3 .

7. A vulcanized silicone rubber bonded steel cord according to claim 1, characterized in that: A primer-free chemical bonding interface is formed between the vulcanized silicone rubber and the steel bar, the 180° peeling strength is greater than 4.0 N / mm, and the peeling interface failure mode is 100% cohesive failure.

8. A method of processing vulcanized silicone rubber connected steel wire according to claim 4, characterized by: After step (4), the method further comprises a step of performing a secondary vulcanization treatment on the product; the secondary vulcanization treatment is performed at 200°C for 2 hours to eliminate low molecular residues and further improve the material resilience.