TPR touch high-elastic quick-rebound modified silica gel material and preparation process thereof

Abstract

This invention discloses a TPR (Total Physical Resin) modified silicone material with high elasticity and fast rebound, and its preparation process. It is composed of the following raw materials in parts by weight: 100-120 parts of low-vinylmethyl vinyl silicone raw rubber, 20-30 parts of fumed silica, 10-20 parts of softening and modifying agent, 2.0-3.0 parts of peroxide curing agent, and 0.5-2.0 parts of silane coupling agent. The modified silicone material has a Shore hardness of 10-22A and possesses instantaneous rapid rebound characteristics. Using low-vinylmethyl vinyl silicone raw rubber as the base material, combined with specific amounts of softening and modifying agent (10-20 parts) and fumed silica (20-30 parts), through the synergistic effect of each component, the modified silicone material can still maintain high crosslinking efficiency and network structure integrity within the soft range where the Shore hardness drops to 10-22A.

Description

Technical Field

[0001] This invention relates to the field of organosilicon materials technology, specifically a TPR (tactile PR) modified silicone material with high elasticity and fast rebound and its preparation process. Background Technology

[0002] Silicone rubber is a type of polymeric elastic material with silicon-oxygen bonds as the main chain and organic groups as side chains. Due to its excellent high and low temperature resistance, weather resistance, electrical insulation, and physiological inertness, it is widely used in aerospace, electronics, automotive machinery, medical and health fields, and everyday life. Among silicone rubber products, compression-molded products occupy an important position, including various gaskets, shock absorbers, buttons, and sheaths. These products often have high requirements for the material's softness, resilience, and tactile feel.

[0003] Currently, most silicone rubber products are manufactured using peroxides as vulcanizing agents through high-temperature compression molding. Traditional compression molding temperatures are typically between 180 and 220°C. While this traditional production process is mature and stable, it also presents some significant challenges. First, the high-temperature vulcanization process consumes a lot of energy, and the ambient temperature in the molding workshop rises accordingly, negatively impacting the comfort of workers. Second, the decomposition of peroxide vulcanizing agents at high temperatures produces byproducts that remain in the product, generating an unpleasant odor and requiring secondary baking for removal. Furthermore, when the purity of the vulcanizing agent is insufficient, the decomposition products easily migrate to the product surface, resulting in a white crystalline phenomenon commonly known as "blooming," affecting the product's appearance and quality. In addition, achieving high elasticity and rapid rebound with traditional silicone rubber at low hardness (e.g., Shore hardness 10-22A) often presents significant technical difficulties—lower hardness usually means lower crosslinking density, easily leading to insufficient resilience and increased compression set. To address this issue, the inventors have proposed a TPR (Total Physical Resin) modified silicone material with high elasticity and rapid rebound, along with its preparation process. Summary of the Invention

[0004] To address the shortcomings of the aforementioned technologies, this invention provides a TPR (Touch-Resistant, High-Elasticity, Fast-Rebound) modified silicone material and its preparation process.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a TPR (Total Physical Resin) tactile, high-elasticity, fast-rebound modified silicone material and its preparation process, comprising the following raw materials in parts by weight: 100-120 parts of low-vinyl methyl vinyl silicone raw rubber, 20-30 parts of fumed silica, 10-20 parts of softening and modifying agent, 2.0-3.0 parts of peroxide vulcanizing agent, and 0.5-2.0 parts of silane coupling agent; the modified silicone material has a Shore hardness of 10-22A and possesses instantaneous rapid rebound characteristics.

[0006] As further explained, the peroxide vulcanizing agent is a 20CS type vulcanizing agent.

[0007] As further explained, the raw materials also include 0 to 4 parts of environmentally friendly color masterbatch and / or additives.

[0008] As further explained, S1 mixing: The low-vinyl methyl vinyl silicone raw rubber is put into a rubber mixing mill, and the fumed silica, softening modifier, and silane coupling agent are added in sequence. After re-mixing, it is passed through a thin stream 5 to 10 times to ensure that the components are evenly dispersed; S2 room temperature curing: The mixed rubber compound is allowed to stand at room temperature for 8 to 20 hours for curing; S3 vulcanizing agent re-mixing: The cured rubber compound is re-mixed, the peroxide vulcanizing agent is added, and it is re-mixed evenly; S4 compression molding: The re-mixed rubber compound is placed in a mold and molded at 150 to 180°C and a mold closing pressure of 10 to 20 MPa. During the molding process, intermittent venting is performed 1 to 5 times, and the vulcanization time is controlled according to the product thickness × 50 to 130 seconds / mm; S5 post-treatment: The product is trimmed after demolding.

[0009] As a further explanation, in step (S4), the molding temperature is 150-180°C.

[0010] As a further explanation, in step (S5), the post-processing also includes baking the trimmed product a second time at 120-150°C for 2-4 hours.

[0011] As a further explanation, in step (S1), the number of times the thin tube is passed is 5 to 8.

[0012] As a further explanation, in step (S2), the time for aging at room temperature is 8 to 16 hours.

[0013] As a further explanation, in step (S4), the number of intermittent exhausts is 1 to 3 times.

[0014] As a further explanation, a TPR-modified silicone material with high elasticity and fast rebound is used in the preparation of plastic composite parts, decompression toys, anti-slip and shock-absorbing components, waterproof sealing parts, soft rubber products for mothers and babies, cushioning covers for electronic products, outdoor protective accessories, craft gift pendants, bathroom and water play products, or soft cushioning parts for automotive interiors.

[0015] In summary, the present invention has the following beneficial effects: The present invention provides a TPR-modified silicone material with high elasticity and fast rebound, and its preparation process. It uses low-vinylmethylvinyl silicone raw rubber as the base material, combined with specific amounts of softening modifiers (10-20 parts) and fumed silica (20-30 parts). Through the synergistic effect of these components, the modified silicone material can maintain high crosslinking efficiency and network structure integrity even within the soft range where the Shore hardness drops to 10-22A. The softening modifiers reduce intermolecular forces and improve molecular chain flexibility without excessively diluting the crosslinking density, allowing the material to instantly recover its deformation after being compressed by external force, exhibiting "fast rebound" characteristics. This effectively overcomes the technical problems of insufficient resilience and increased compression set that often occur in traditional low-hardness silicone rubber due to decreased crosslinking density. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] This invention discloses a TPR (Total Resin) modified silicone material with high elasticity and fast rebound, and its preparation process. The material comprises the following raw materials in parts by weight: 100-120 parts of low-vinylmethylvinyl silicone raw rubber, 20-30 parts of fumed silica, 10-20 parts of softening and modifying agent, 2.0-3.0 parts of peroxide curing agent, and 0.5-2.0 parts of silane coupling agent. The modified silicone material has a Shore hardness of 10-22A and exhibits instantaneous rapid rebound characteristics. The peroxide curing agent is a 20CS type curing agent. The raw materials also include 0-4 parts of environmentally friendly color masterbatch and / or additives.

[0018] Specifically, methyl vinyl silicone raw rubber with a low vinyl content is used as the base compound. The vinyl side groups provide active crosslinking points for vulcanization crosslinking, while the "low vinyl" design means a relatively low density of crosslinking points on the molecular chain. The principle behind this choice is that during vulcanization, the lower vinyl content avoids over-crosslinking, keeping the crosslinking density of the vulcanizate at an appropriate level, thus giving the material lower hardness (Shore 10–22A) and a soft TPR feel. At the same time, a moderate crosslinking density is sufficient to construct a complete three-dimensional network structure, providing the necessary resilience driving force for the material and preventing excessive softening and loss of resilience in the product due to insufficient crosslinking points.

[0019] Fumed silica (nano-sized silica) has a surface rich in silanol groups (Si–OH). During the compounding process, these silanol groups form hydrogen bonds with the silicone rubber molecular chains. Simultaneously, after treatment with a silane coupling agent, some fumed silica particles are chemically grafted onto the silicone rubber molecular chains. This combined effect of physical adsorption and chemical bonding results in a uniformly dispersed nanoscale reinforcing network of fumed silica particles within the silicone rubber matrix. This reinforcing network significantly improves the mechanical strength of the silicone rubber, compensating for the strength loss caused by low crosslinking density. Furthermore, the hydrogen bonding interactions between the fumed silica particles impart a certain degree of thixotropy to the compound, which is beneficial for improving mold filling flow and release properties during compression molding.

[0020] The softening modifier is the key component in achieving the balance of "low hardness + high resilience" in this invention. Its working principle is as follows: the softening modifier molecules insert into the spaces between silicone rubber molecular chains, weakening the van der Waals forces between the chains, increasing the interchain spacing, and reducing the internal frictional resistance of chain segment movement, thereby significantly improving the material's macroscopic softness and flexibility. More importantly, while reducing hardness, the softening modifier of this invention does not cause destructive dilution to the vulcanization crosslinking network. Specific groups in its molecular structure can form appropriate compatibility or weak bonds with the silicone rubber matrix, and can be simultaneously fixed in the network structure during the vulcanization process along with the crosslinking reaction. This avoids the performance degradation caused by migration and precipitation of traditional softening oils during use, thus maintaining a high rebound rate and low compression set under low hardness conditions.

[0021] A 20CS type peroxide vulcanizing agent is used. Its basic principle of vulcanization crosslinking is as follows: under heating conditions, the peroxide bonds (–O–O–) in the peroxide vulcanizing agent molecule undergo homolytic cleavage, generating two highly reactive free radicals. These free radicals abstract hydrogen atoms from the vinyl side groups or methyl groups on the silicone raw rubber molecular chain, forming active free radical sites on the molecular chain. This, in turn, initiates a free radical coupling reaction between the silicone rubber molecular chains, forming carbon-carbon crosslinking bonds, thus crosslinking the linear silicone raw rubber molecular chains into a three-dimensional network structure. This invention selects a 20CS type vulcanizing agent, whose decomposition temperature matches the molding temperature of 140–180°C set in this invention. Sufficient and uniform crosslinking can be achieved at a lower temperature, while minimizing decomposition byproducts, thus reducing odor and blooming problems at the source.

[0022] Silane coupling agents contain both hydrolyzable groups (such as alkoxy groups) that can react with the silanol groups on the surface of inorganic silica and organic functional groups that can react with or be compatible with the molecular chains of organosilicon raw rubber. Their working principle is as follows: In a silica-filled silicone rubber system, one end of the silane coupling agent forms a Si–O–Si chemical bond with the silanol groups on the silica surface through a hydrolytic condensation reaction, while the other end binds to the silicone raw rubber molecular chains through physical entanglement or chemical reaction. This creates a "molecular bridge" between the silica and the silicone rubber matrix, significantly improving the interfacial bonding between the inorganic filler and the organic matrix, promoting the uniform dispersion of silica, and enhancing the overall mechanical properties of the vulcanized rubber.

[0023] S1 Mixing: Add low-vinyl methyl vinyl silicone raw rubber to a mixing mill, then add fumed silica, softening modifier, and silane coupling agent in sequence. After remixing, pass through a thin stream 5-10 times to ensure uniform dispersion of all components. S2 Room Temperature Curing: Allow the mixed rubber compound to cure at room temperature for 8-20 hours. S3 Vulcanizing Agent Remixing: Remix the cured rubber compound, add peroxide vulcanizing agent, and remix until uniform. S4 Compression Molding: Place the remixed rubber compound in a mold and compress it at 150-180℃ and a mold closing pressure of 10-20MPa. During the molding process, perform 1-5 intermittent venting operations. The vulcanization time is controlled according to the product thickness × 50-130 seconds / mm. S5 Post-treatment: Trim the product after demolding.

[0024] In step (S4), the molding temperature is 150–180°C. In step (S5), the post-processing includes baking the trimmed product a second time at 120–150°C for 2–4 hours. In step (S1), the thin-passing is performed 5–8 times. In step (S2), the curing time at room temperature is 8–16 hours. In step (S4), the intermittent venting is performed 1–3 times.

[0025] Specifically, in the mixing process, after 5-10 passes through the mill, the rubber compound is repeatedly subjected to intense compression and shearing within the gap between the two rollers of the mixing mill. During this process, powdered or liquid components such as fumed silica and softening modifiers are forcibly embedded into the silica raw rubber matrix and gradually broken down and dispersed under shear stress, ultimately achieving a uniform distribution at the submicroscopic scale. The thin-passing operation also eliminates air bubbles trapped within the rubber compound, improving its density and uniformity, thus ensuring the consistent progress of the subsequent vulcanization and crosslinking reactions.

[0026] After mixing, the rubber compound is allowed to stand and mature at room temperature for 8–20 hours. Its working principle involves two aspects: First, at the physical level, the molecular chains of the raw silicone rubber and components such as silica and softening modifiers undergo molecular diffusion and chain segment rearrangement, further eliminating the internal stress generated during the mixing process, making the interface distribution between the components more uniform and stable, and improving the plasticity and processing stability of the rubber compound. Second, at the chemical level, the silane coupling agent continues to undergo hydrolysis and condensation reactions with the silanol groups on the surface of silica, further increasing the grafting coverage of the coupling agent on the silica surface, thereby enhancing the interfacial bonding strength between silica and the silicone rubber matrix.

[0027] The molding vulcanization temperature is controlled at 140–180℃ (preferably 150–180℃), which is lower than the traditional process (165–200℃). The principle behind this is that the 20CS type peroxide vulcanizing agent has a suitable decomposition half-life within this temperature range. This ensures that the vulcanization rate meets production efficiency requirements while allowing the crosslinking reaction to proceed gently, avoiding excessively vigorous free radical coupling reactions at high temperatures that could lead to uneven or excessively high crosslinking density. The vulcanization time is controlled at 50–130 seconds per millimeter of product thickness. This is essentially based on the law of thermal conduction (the time required for the internal temperature of the rubber compound to reach the vulcanization temperature is proportional to the square of the thickness) and the kinetics of the crosslinking reaction, ensuring that both thick and thin products achieve sufficient and uniform crosslinking.

[0028] The working principle of a mold closing pressure of 10-20 MPa is as follows: sufficient mold closing pressure can overcome the flow resistance of the rubber material during mold filling, allowing the rubber material to completely fill all the details of the mold cavity. At the same time, it compacts the rubber material and expels excess gas, ensuring accurate product dimensions and a dense structure. Intermittent venting is performed 1-5 times during the molding process. The mechanism is as follows: in the initial stage of mold closing and pressurization, the rubber material softens due to heat and flows under pressure to fill the mold, compressing the gas trapped inside the mold cavity and the rubber material. By briefly opening the mold to release the pressure, the compressed gas expands and escapes. After the mold closes again, air bubble defects inside the product are effectively eliminated, ensuring the product's density and appearance quality.

[0029] The trimmed product is then baked a second time at 120–150°C for 2–4 hours. The principle behind this is that during the compression molding and vulcanization process, some low-molecular-weight byproducts (such as acetophenone and alcohols) produced by the decomposition of the peroxide vulcanizing agent remain physically dispersed or dissolved within the silicone rubber network. The second baking, conducted at a temperature higher than or close to the vulcanization temperature, intensifies the thermal motion of the silicone rubber molecular chains, increases the free volume of the network structure, and provides more ample diffusion channels for the low-molecular-weight byproducts. This promotes their migration from the interior of the product to the surface and their volatilization, effectively eliminating the product's odor and preventing the byproducts from crystallizing and precipitating on the surface after cooling, thus preventing "blooming."

[0030] Application of a TPR-modified silicone material with high elasticity and fast rebound in the preparation of plastic composite parts, decompression toys, anti-slip and shock-absorbing components, waterproof sealing parts, soft rubber products for mothers and babies, cushioning covers for electronic products, outdoor protective accessories, craft gift pendants, bathroom and water play products, or soft cushioning parts for automotive interiors.

[0031] Specifically, using low-vinyl methyl vinyl silicone raw rubber as the network skeleton, fumed silica as the reinforcing filler, and softening modifiers to reduce the frictional resistance between molecular chains and impart a soft feel, the organic-inorganic interface is strengthened by silane coupling agents, and a moderately cross-linked three-dimensional network structure is constructed under the low-temperature cross-linking action of 20CS type peroxide vulcanizing agent. Combined with thin-pass dispersion, room temperature curing, low-temperature molding degassing, and secondary baking processes, a performance balance of "low hardness (10~22A) - high elasticity - instantaneous rebound" is finally achieved in silicone rubber materials, while giving the material excellent TPR feel, low odor, no blooming, and good processability.

[0032] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0033] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A TPR touch high-elastic quick-rebound modified silica gel material, characterized in that, It consists of the following raw materials in parts by weight: 100-120 parts of low-vinyl methyl vinyl silicone raw rubber, 20-30 parts of fumed silica, 10-20 parts of softening and modifying agent, 2.0-3.0 parts of peroxide vulcanizing agent, and 0.5-2.0 parts of silane coupling agent; The modified silicone material has a Shore hardness of 10-22A and possesses instantaneous rapid rebound characteristics.

2. The TPR touch high-elastic quick-rebound modified silica gel material according to claim 1, characterized in that: The peroxide vulcanizing agent is a 20CS type vulcanizing agent.

3. The TPR touch high-elastic quick-rebound modified silica gel material according to claim 1, characterized in that: The raw materials also include 0 to 4 parts of environmentally friendly color masterbatch and / or additives.

4. The preparation process of the TPR touch high-elastic quick-rebound modified silica gel material according to any one of claims 1 to 3, characterized in that: S1 Mixing: The low vinyl methyl vinyl silicone raw rubber is put into a rubber mixing mill, and the fumed silica, softening modifier, and silane coupling agent are added in sequence. After refining, it is passed through a thin stream 5 to 10 times to make the components evenly dispersed. S2 room temperature curing: Let the mixed rubber compound stand at room temperature for 8 to 20 hours to cure; S3 vulcanizing agent refining: The cured rubber compound is refining, the peroxide vulcanizing agent is added and refining is uniform; S4 Compression Molding: Place the refined rubber compound in a mold and compress it at 150-180℃ and a mold closing pressure of 10-20MPa. During the molding process, perform 1-5 intermittent ventings. The vulcanization time is controlled according to the product thickness × 50-130 seconds / mm. S5 Post-processing: Trimming the product after demolding.

5. The process for preparing a TPR touch high-elastic quick-rebound modified silica gel material according to claim 4, characterized in that, In step (S4), the molding temperature is 150-180°C.

6. The process for preparing a TPR touch high-elastic quick-rebound modified silica gel material according to claim 4, characterized in that, In step (S5), the post-processing further includes baking the trimmed product a second time at 120-150°C for 2-4 hours.

7. The preparation process of a TPR-modified silicone material with high elasticity and fast rebound according to claim 4, characterized in that, In step (S1), the thin tube is passed through 5 to 8 times.

8. The preparation process of a TPR-modified silicone material with high elasticity and fast rebound according to claim 4, characterized in that, In step (S2), the time for aging at room temperature is 8 to 16 hours.

9. The preparation process of a TPR-modified silicone material with high elasticity and fast rebound according to claim 4, characterized in that, In step (S4), the number of intermittent exhausts is 1 to 3 times.

10. The application of a TPR-modified silicone material with high elasticity and fast rebound according to any one of claims 1 to 3 in the preparation of plastic composite parts, decompression toys, anti-slip and shock-absorbing components, waterproof sealing parts, soft rubber products for mothers and babies, cushioning covers for electronic products, outdoor protective accessories, craft gift pendants, bathroom and water play products, or soft cushioning parts for automotive interiors.