Stain-resistant silicone rubber watchband as well as preparation method and application thereof

Abstract

The invention provides a smudginess-resistant silicone rubber watchband as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The silicone rubber watchband is prepared from the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 20-45 parts of fumed silica, 0.5-5 parts of a fluorine-containing surfactant, 1-5 parts of POSS (Polyhedral Oligomeric Silsesquioxane) modified silicone oil, 1-3 parts of a structured control agent, 0.5-2 parts of a vulcanizing agent and 1-5 parts of a coloring agent. Through the synergistic effect of the fluorine-containing surfactant and the POSS modified silicone oil, the watchband is extremely low in surface energy, has excellent hydrophobic and oleophobic properties, can effectively resist attachment and permeation of common dirt such as sweat and oil stains, keeps the inherent softness, elasticity and comfort of silicone rubber, and is suitable for production of watchbands of wearable devices such as smart watches and bracelets.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a watch strap material for smart wearable devices, and more particularly to a silicone rubber watch strap with excellent dirt resistance, its preparation method, and its application. Background Technology

[0002] Silicone rubber has become the preferred material for watch straps in wearable devices such as smartwatches, smart bracelets, and traditional wristwatches due to its excellent softness, biocompatibility, resistance to high and low temperatures, ease of processing and molding, and moderate cost. However, conventional liquid silicone rubber or high-temperature vulcanized silicone rubber has a significant drawback: poor resistance to dirt. This is mainly reflected in: (1) easily adsorbing fine particles such as dust and dander in the environment; (2) easily being stained and penetrated by colored or oily substances such as sweat, oil stains, cosmetics (such as foundation and lipstick), and ink; (3) once stained, cleaning is very difficult and can easily leave permanent marks. These problems seriously affect the appearance and user experience of the product, shorten the actual service life of the watch strap, and fail to meet the market demand for high-end wearable products that combine comfort and durability and are easy to maintain.

[0003] To improve the surface properties of materials, existing technologies have explored various approaches. For example, patent application CN116285675A discloses a hydrophobic silane coating functionalized with cage-like silsesquioxane (POSS), applied to fabric or metal surfaces via dip coating or spraying to impart superhydrophobic and corrosion-resistant properties to the substrate. However, this technology does not involve composites with silicone rubber or mention applications in flexible, highly elastic wearable devices. Patent CN118085287B discloses a stain- and water-resistant additive for coatings, combining POSS with fluorinated silanes to reduce the surface energy of the coating, achieving self-cleaning and anti-graffiti effects. However, its application is also limited to the coating field, rather than silicone rubber as the main material.

[0004] In summary, current technologies lack a long-term solution that can fundamentally improve the dirt resistance of silicone rubber while fully retaining its inherent softness, high elasticity, and comfort, making it suitable for use in situations like watch straps where the material is constantly in close contact with the skin. Therefore, developing a novel dirt-resistant silicone rubber watch strap material has significant practical application value. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing silicone rubber watch straps, which are prone to absorbing stains and are difficult to clean. This invention provides a dirt-resistant silicone rubber watch strap with excellent and durable hydrophobic and oleophobic properties, which can effectively resist the adhesion and penetration of common dirt, as well as its preparation method and application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a silicone rubber compound, which is prepared from the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 20-45 parts of fumed silica, 0.5-5 parts of fluorinated surfactant, 1-5 parts of POSS modified silicone oil, 1-3 parts of structure control agent, 0.5-2 parts of vulcanizing agent, and 0-5 parts of colorant.

[0007] Furthermore, the silicone rubber compound is prepared from the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 40 parts of fumed silica, 1-3 parts of fluorinated surfactant, 1-5 parts of POSS modified silicone oil, 1-2 parts of structure control agent, 1 part of vulcanizing agent, and 1-2 parts of colorant.

[0008] Furthermore, the silicone rubber compound is prepared from the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 40 parts of fumed silica, 3 parts of fluorinated surfactant, 5 parts of POSS modified silicone oil, 2 parts of structure control agent, 1 part of vulcanizing agent, and 1 part of colorant.

[0009] Furthermore, the fluorinated surfactant is at least one of a perfluoroalkyl ethyl acrylate copolymer or a fluorocarbon-modified polysiloxane.

[0010] Furthermore, the POSS-modified silicone oil is a graft copolymer of methacryloxypropyl-POSS and hydroxyl-terminated silicone oil.

[0011] Furthermore, the POSS-modified silicone oil is prepared by graft copolymerization of methacryloxypropyl-POSS and hydroxyl-terminated silicone oil, using azobisisobutyronitrile as an initiator (wherein the molar ratio of methacryloxypropyl-POSS, hydroxyl-terminated silicone oil and azobisisobutyronitrile is 1:0.5:0.01), and toluene as a solvent. The reaction is carried out by continuous stirring at 75°C and under a nitrogen atmosphere for 8 hours to obtain the POSS-modified silicone oil through free radical graft copolymerization.

[0012] Further, the vulcanizing agent is at least one of bis-2,4-dicumyl peroxide or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0013] Further, the methyl vinyl silicone rubber raw material is 110-2; the fumed silica is R972; the fluorinated surfactant is fluorocarbon modified polysiloxane; the structuring control agent is hydroxyl silicone oil; the vulcanizing agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; and the colorant is titanium dioxide.

[0014] The present invention also provides a method for preparing the above-mentioned silicone rubber compound, the method comprising the following steps: mixing and mixing raw materials, open milling, vulcanizing and secondary vulcanizing, to obtain the silicone rubber compound.

[0015] Furthermore, the method includes the following steps: (1) Internal mixing: put methyl vinyl silicone rubber raw rubber, fumed silica and structure control agent into a kneader, mix and internally mix to obtain a uniform silicone base material; (2) Open milling and addition of additives: Transfer the silicone base material obtained in step (1) to an open mill, pass it through a thin mill, add the fluorinated surfactant and POSS modified silicone oil in sequence, and mix thoroughly until evenly dispersed; (3) Vulcanization: Add vulcanizing agent and colorant to the compound obtained in step (2), continue to mix evenly and then sheet out, put the sheet into a preheated mold and vulcanize; (4) Secondary vulcanization: The molded watch strap is placed in an oven for secondary vulcanization to obtain the silicone rubber compound.

[0016] Furthermore, in step (1), the mixing temperature is 50~80℃ and the time is 20~40 minutes; In step (3), the vulcanization temperature is 160~180℃, the pressure is 10~15MPa, and the time is 5~15 minutes; In step (4), the temperature of the secondary vulcanization is 180~200℃ and the time is 2~4 hours.

[0017] The present invention also provides the application of the above-mentioned silicone rubber compound in the preparation of silicone rubber watch straps.

[0018] The present invention has achieved the following beneficial effects: The silicone watch strap produced by this invention has extremely low surface energy and excellent hydrophobic and oleophobic properties. It can effectively resist the adhesion and penetration of common dirt such as sweat, oil stains, cosmetics, and ink, while maintaining the inherent softness, comfort, and high elasticity of silicone material, greatly extending the clean service life of the watch strap.

[0019] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0020] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto. The raw materials and equipment used in the present invention are all known products, obtained by purchasing commercially available products.

[0022] In the formulations of this invention, "parts" refers to parts by mass, a relative unit for expressing the amount of raw materials used. Based on the mass of raw rubber, its usage is defined as 100 parts. The usage of other compounding agents (such as vulcanizing agents, accelerators, fillers, etc.) is expressed as parts by mass relative to the raw rubber. For example, if the vulcanizing agent is listed as 1 part in the formulation, it means that 1 part of vulcanizing agent is added for every 100 parts of raw rubber.

[0023] Explanation of abbreviations for raw materials used in the examples: "110-2": Methyl-terminated methyl vinyl silicone rubber, model: 110-2, vinyl content: 0.13%~0.20%; volatile matter (150℃×3h): ≤2.0%. Brand: Nanjing Dongjue Organosilicon Co., Ltd.

[0024] “R972”: is fumed silica in hydrophobic silica, brand: DEGUSSA; model: AEROSIL R972.

[0025] "Fluorocarbon modified polysiloxane": a commercially available fluorinated surfactant, brand: Guangzhou Huitu New Materials Co., Ltd.; model: HT-3102.

[0026] "POSS modified silicone oil": In this embodiment, it is prepared by graft copolymerization of methacryloyloxypropyl-POSS and hydroxyl-terminated silicone oil. Azobisisobutyronitrile is used as the initiator (wherein, the molar ratio of methacryloyloxypropyl-POSS, hydroxyl-terminated silicone oil and azobisisobutyronitrile is 1:0.5:0.01), and toluene is used as the solvent. The reaction is carried out by stirring continuously at 75°C and under a nitrogen atmosphere for 8 hours to obtain POSS modified silicone oil through free radical graft copolymerization.

[0027] "Hydroxysilicone oil": Brand: Xin'an Chemical; Model: OH-003, hydroxyl value: 10%, viscosity: 200 cst.

[0028] "Double-5": 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane.

[0029] Example 1: Preparation of silicone rubber compound Example 1 provides a silicone rubber compound comprising the raw materials shown in Table 1 by weight: Table 1 Raw material ratio table for Example 1 The preparation method of the above-mentioned silicone rubber compound is as follows: (1) Internal mixing: 100 parts of methyl vinyl silicone rubber raw rubber (110-2), 40 parts of fumed silica (R972) and 2 parts of structure control agent (hydroxyl silicone oil) are put into a kneader and mixed at 80°C for 30 minutes to obtain a uniform silicone base material; the above base material is left to stand at room temperature for 24 hours. (2) Open milling and addition of additives: Transfer the rubber compound after it has been left to an open mill, and after passing it through a thin mill several times, add 2 parts of fluorinated surfactant (fluorocarbon modified polysiloxane) and 2 parts of POSS modified silicone oil in sequence, and mix thoroughly until it is evenly dispersed; (3) Vulcanization: Continue to add 1 part vulcanizing agent (double 25) and 2 parts colorant (titanium dioxide) to the open mill, mix evenly and then extrude the film. Place the film into the preheated mold and mold it for 6 minutes at 170℃ and 12MPa pressure. (4) Secondary vulcanization: The molded watch strap is placed in an oven and vulcanized at 200°C for 2 hours to obtain the high dirt-resistant silicone watch strap.

[0030] Example 2: Preparation of silicone rubber compound Example 2 provides a silicone rubber compound comprising the raw materials shown in Table 2 by weight: Table 2 Raw material ratio table for Example 2 The preparation method of the silicone rubber compound in this embodiment is the same as that in Embodiment 1.

[0031] Example 3: Preparation of silicone rubber compound Example 3 provides a silicone rubber compound comprising the raw materials shown in Table 3 by weight: Table 3 Raw material ratio table for Example 3 The preparation method of the silicone rubber compound in this embodiment is the same as that in Embodiment 1.

[0032] Example 4: Preparation of silicone rubber compound Example 4 provides a silicone rubber compound comprising the raw materials shown in Table 4 by weight: Table 4 Raw material ratio table for Example 4 The preparation method of the silicone rubber compound in this embodiment is the same as that in Embodiment 1.

[0033] The following is a comparative example.

[0034] Comparative Example 1: Preparation of Silicone Rubber Compound Comparative Example 1 provides a silicone rubber compound comprising the raw materials shown in Table 5 in parts by weight: Table 5 Raw material ratio table for Example 5 The preparation method of the silicone rubber compound in this comparative example is the same as that in Example 1.

[0035] The following experimental examples demonstrate the beneficial effects of the present invention.

[0036] Experimental Example 1: Performance Testing of Silicone Rubber Compound The surface properties and media resistance properties of the silicone rubber samples prepared in Comparative Example 1 and Examples 1-4 were tested.

[0037] 1. Experimental Methods Contact angle test: A certain volume of liquid droplet, such as water droplet or oil droplet, is dropped onto the sample surface using a micro-syringe. The outline of the droplet is then photographed through an optical system, and the contact angle is calculated by fitting the droplet edge using image analysis software. Water resistance test: Immerse the rubber product in deionized water at 40°C for 168 hours, then remove it. The rubber product should show no significant change in appearance, have a mass change rate of <1%, and retain >95% of its tensile strength. Oil resistance test: Immerse the rubber product in lubricating oil at 23°C for 48 hours, then remove it. The rubber product should show no significant change in appearance, have a mass change rate of <1%, and retain >95% of its tensile strength.

[0038] 2. Experimental Results The test results are shown in Table 6 below.

[0039] Table 6 Performance Test Results Results analysis: As shown in Table 6, although Comparative Example 1 (without fluorinated surfactants and POSS modified silicone oil) has a certain degree of hydrophobicity (water contact angle 92°) due to the inherent properties of silicone rubber, its oleophobicity is very poor (oil contact angle only 74°), and it is easily contaminated by oily substances.

[0040] In comparison, the water contact angle and oil contact angle of all the sample examples were significantly higher than those of Comparative Example 1. Example 4, in particular, exhibited the best overall performance with its optimized formulation (3 parts fluorinated surfactant and 5 parts POSS-modified silicone oil), achieving a water contact angle of 127° and an oil contact angle of 108°. This data indicates that the sample surface of this example achieved a highly hydrophobic and oleophobic state, with extremely low surface energy. Theoretically, it has the strongest resistance to common water-based and oil-based stains (such as sweat, cooking oil, emulsions, etc.), making it difficult for stains to spread and adhere to its surface, thus achieving optimal dirt resistance and easy cleaning. Example 2 (2 parts fluorinated surfactant and 4 parts POSS-modified silicone oil) also performed well, with a water contact angle of 119° and an oil contact angle of 102°, demonstrating that excellent performance can be obtained with appropriate proportions. Examples 1 and 3 showed slightly better results, but were still significantly superior to the comparative example. This indicates that within the formulation range described in this invention (0.5-3 parts of fluorinated surfactant and 1-5 parts of POSS modified silicone oil), the addition of the two key additives can significantly and synergistically improve the dirt resistance performance. Moreover, within the experimental gradient, the performance shows an increasing trend with the increase of the amount added, with the formulation of Example 4 being the optimal choice within the current test range.

[0041] All samples passed basic water and oil resistance tests, indicating that the material's bulk properties are stable. In summary, Example 4 not only possesses excellent hydrophobic and oleophobic surface properties, but also passed standard media resistance tests, demonstrating its stability and reliability. It is a preferred embodiment of the technical solution of this invention.

[0042] In summary, this invention, through specific formulation and process, successfully prepared a watch strap material that combines excellent dirt resistance with the inherent advantages of silicone rubber, solving a pain point in the industry and showing promising application prospects.

Claims

1. A silicone rubber compound, characterized in that, The silicone rubber compound is prepared from the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 20-45 parts of fumed silica, 0.5-5 parts of fluorinated surfactant, 1-5 parts of POSS modified silicone oil, 1-3 parts of structure control agent, 0.5-2 parts of vulcanizing agent, and 0-5 parts of colorant.

2. The silicone rubber compound according to claim 1, characterized in that, The silicone rubber compound is prepared from the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 40 parts of fumed silica, 1-3 parts of fluorinated surfactant, 1-5 parts of POSS modified silicone oil, 1-2 parts of structure control agent, 1 part of vulcanizing agent, and 1-2 parts of colorant.

3. The silicone rubber compound according to claim 2, characterized in that, The silicone rubber compound is prepared from the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 40 parts of fumed silica, 3 parts of fluorinated surfactant, 5 parts of POSS modified silicone oil, 2 parts of structure control agent, 1 part of vulcanizing agent, and 1 part of colorant.

4. The silicone rubber compound according to claim 1, characterized in that, The fluorinated surfactant is at least one of a perfluoroalkyl ethyl acrylate copolymer or a fluorocarbon-modified polysiloxane.

5. The silicone rubber compound according to claim 1, characterized in that, The POSS-modified silicone oil is a graft copolymer of methacryloyloxypropyl-POSS and hydroxyl-terminated silicone oil.

6. The silicone rubber compound according to claim 1, characterized in that, The vulcanizing agent is at least one of bis-2,4-dicumyl peroxide or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

7. A method for preparing the silicone rubber compound according to any one of claims 1-6, characterized in that, Includes the following steps: The raw materials are mixed and kneaded, then subjected to open milling, vulcanization, and secondary vulcanization to obtain the silicone rubber compound.

8. The method according to claim 7, characterized in that, The method includes the following steps: (1) Internal mixing: put methyl vinyl silicone rubber raw rubber, fumed silica and structure control agent into a kneader, mix and internally mix to obtain a uniform silicone base material; (2) Open milling and addition of additives: Transfer the silicone base material obtained in step (1) to an open mill, pass it through a thin mill, add the fluorinated surfactant and POSS modified silicone oil in sequence, and mix thoroughly until evenly dispersed; (3) Vulcanization: Add vulcanizing agent and colorant to the compound obtained in step (2), continue to mix evenly and then sheet out, put the sheet into a preheated mold and vulcanize; (4) Secondary vulcanization: The molded watch strap is placed in an oven for secondary vulcanization to obtain the silicone rubber compound.

9. The method according to claim 8, characterized in that, In step (1), the mixing temperature is 50~80℃ and the time is 20~40 minutes; In step (3), the vulcanization temperature is 160~180℃, the pressure is 10~15MPa, and the time is 5~15 minutes; In step (4), the temperature of the secondary vulcanization is 180~200℃ and the time is 2~4 hours.

10. The use of the silicone rubber compound according to any one of claims 1 to 6 in the preparation of silicone rubber watch straps.

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