A two-color gradient silicone watchband and a preparation method thereof

Abstract

The application discloses a kind of two-color gradient silica gel watchband and preparation method thereof, belong to watchband processing technical field.The two-color gradient silica gel watchband includes base layer, is located the two-color gradient layer of base layer surface and is located the cladding layer of two-color gradient layer surface;The base layer thickness is 1.55±0.2mm, the two-color gradient layer thickness is 0.15±0.05mm, and the total thickness of watchband is 3-4mm.The interface bonding strength between silica gel matrix and ink layer is significantly improved by plasma activation treatment;By using gradient screen printing process, the natural continuous transition of two-color silica gel ink is realized;By setting cladding layer and combining vacuum exhaust and step vulcanization process, the wear resistance, sweat resistance and bending fatigue resistance of watchband are improved.

Description

Technical Field

[0001] This invention relates to the field of watch strap processing technology, specifically to a two-tone gradient silicone watch strap and its preparation method. Background Technology

[0002] Silicone watch straps are widely used in smart wearable devices, electronic watches, and sports watches due to their advantages such as softness and skin-friendliness, sweat resistance, good weather resistance, comfortable wear, and ease of molding. Liquid silicone, in particular, has characteristics such as good fluidity, high molding precision, and excellent resilience, making it suitable for manufacturing watch strap products with complex structures and high surface finish requirements.

[0003] As consumer demand for personalized watch strap designs increases, single-color or single-texture silicone watch straps can no longer meet user needs. Multi-color designs are gradually becoming an important development direction for silicone watch straps. In existing technologies, to create a multi-color appearance on the surface of silicone watch straps, methods such as spraying, pad printing, and ordinary printing are typically used to form a decorative layer on the substrate surface.

[0004] Existing silicone watch straps still face several challenges in producing multi-color designs. First, the silicone substrate itself has low surface energy, resulting in weak adhesion between ordinary inks or coatings and the silicone base. This is especially true under conditions of bending, twisting, stretching, immersion in sweat, or prolonged friction, which can easily lead to issues such as pattern layer peeling, edge lifting, cracking, or localized color fading. Particularly for the ink layer, since multiple colors need to achieve a continuous transition within a small area, insufficient adhesion to the substrate layer can easily result in uneven ink color, weak interlayer bonding, surface discoloration after printing, and localized delamination. Second, in existing technologies, when printing ink directly onto the silicone substrate surface, insufficient substrate surface activation and a lack of effective bonding medium at the ink-substrate interface can lead to high internal stress after ink curing, affecting the stability and durability of the pattern. Finally, existing silicone watch straps are also susceptible to the effects of sweat, sebum, dust, and external friction during long-term wear, leading to surface stains, insufficient abrasion resistance, and loss of gloss in the ink layer.

[0005] Therefore, it is necessary to provide a two-tone gradient silicone watch strap to solve the above problems. Summary of the Invention

[0006] In view of this, the present invention provides a two-color gradient silicone watch strap and its preparation method. By optimizing the composition and production process of the watch strap, the present invention produces a watch strap that is wear-resistant, sweat-resistant, aging-resistant, and has excellent bending resistance and durability.

[0007] To better solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, a two-color gradient silicone watch strap includes a base layer, a two-color gradient layer disposed on the surface of the base layer, and a covering layer disposed on the surface of the two-color gradient layer; the thickness of the base layer is 1.55±0.2mm, the thickness of the two-color gradient layer is 0.15±0.05mm, and the thickness of the two-color gradient silicone watch strap is 3-4mm; the base layer and the covering layer are made of liquid silicone raw material, and the two-color gradient layer is made by screen printing two different colors of silicone ink; the colors of the base layer are all selected from one of transparent, semi-transparent, solid white, and semi-transparent black, and the colors of the covering layer are selected from one of transparent, semi-transparent, and semi-transparent black.

[0008] Secondly, a method for preparing a two-color gradient silicone watch strap includes the following steps: S1. Mix the liquid silicone raw material with the vulcanizing agent to obtain the rubber compound. Place the rubber compound into the mold and cover the mold. Press the mold into the machine and remove the product after the vulcanization time is reached to obtain the base layer. S2. Perform surface activation treatment on the substrate layer; S3. Using a gradient screen, a two-color gradient layer is printed on the surface of the activated substrate layer using screen printing technology, and then cured to form a two-color gradient layer. S4. Place the substrate layer after printing the two-color gradient layer into the mold, cover it with the rubber compound made of liquid silicone raw material and vulcanizing agent, and then perform vacuum degassing and vulcanization to form a watch strap with a coating layer. S5. After punching holes in the watch strap covered with silicone coating, perform post-processing to obtain a two-color gradient silicone watch strap.

[0009] Preferably, in step S1, the vulcanization conditions are: a temperature of 130-140℃ and a pressure of 55-65 kg / cm². 2 The vulcanization time is 250-300 seconds.

[0010] Preferably, in step S2, the surface activation treatment is a plasma activation treatment, the power of the plasma activation treatment is 200-600W, the treatment time is 5-60s, and the type of plasma is oxygen plasma.

[0011] Preferably, in step S3, the parameters of the gradient screen are: thickness: 5μm, mesh size: 420 mesh, gradient length of the gradient screen: 1 / 2 of the length of the gradient screen; the effective opening rate of one end of the gradient screen is 80-90%, the effective opening rate of the gradient screen continuously decreases along the gradient direction, and the effective opening rate of adjacent gradient units varies by 0.5%-3%.

[0012] Preferred printing conditions: number of screens: 2, printing pressure: 0.55-0.65MPa, printing speed: 60-70mm / s, number of printing passes: 2, printing height: 3-5mm; curing treatment is performed after each printing.

[0013] Preferably, the curing process includes: first treating at 80-120℃ for 2-10 minutes, and then treating at 165-170℃ for 20-30 minutes.

[0014] Preferably, in step S4, the vacuum exhaust process includes: -0.04~-0.09MPa, for a time of 2-6 minutes; Preferably, the vulcanization process includes: preheating vulcanization at 120-130℃ for 40-60 seconds, then raising the temperature to 130-140℃, and maintaining a pressure of 110-125 kg / cm². 2 Continue vulcanization under pressure for 210-240 seconds, with the total vulcanization time controlled at 250-300 seconds.

[0015] Preferably, in step S5, the post-processing includes UV light irradiation treatment; the conditions for UV light irradiation treatment are: ultraviolet light with a wavelength of 365nm, a transmission speed of 0.2-0.3m / min, an irradiation height of 60-65mm, an irradiation intensity of 100%, and irradiation once on each side.

[0016] The method for preparing the gradient screen printing plate in this invention is as follows: (1) Image processing: A gradient pattern was created in the image processing software (Adobe Photoshop). To ensure a natural visual transition and facilitate strap assembly, the gradient length was set to 2 / 3 of the effective display length of the strap. The key image processing parameters are as follows: image resolution: 12000 DPI, screen ruling: 100 LPI, dot shape: rhombus, dot angle: 45°, gradient direction: along the longitudinal direction of the strap, the effective aperture ratio at one end of the image is 85%, and the effective aperture ratio variation of adjacent gradient units is 1%. (2) Screen Making: The processed halftone pattern is output as a gradient film with an image recording precision of 12000 DPI, ensuring that there are no burrs on the edges of the halftone dots and that the measured optical density of the image area is ≥3.5. A 400-mesh, 5μm thick yellow polyester screen is used with a stainless steel frame and the tension is controlled at 22N / cm. The tension difference at different points on the same screen is controlled at ≤1.5N / cm. The screen is degreased and dusted and then thoroughly dried in a dust-free environment. The photosensitive emulsion is coated on both sides of the screen and dried to obtain a photosensitive layer with a thickness of 12μm. The film (emulsion side up) and the screen (printing side down) are tightly bonded in a vacuum exposure machine. A 365nm wavelength UV-LED is used as the main exposure light source and the exposure dose is set to 2800 mJ / cm. 2The exposure time is approximately 80 seconds. After exposure, use warm water at 30°C and adjust the water pressure to 0.25 MPa. Use a fan-shaped nozzle to evenly rinse both sides of the screen. The development time is 60 seconds. Place the developed screen in an oven and bake at 50°C for 30 minutes to obtain a gradient screen.

[0017] Compared with the prior art, the present invention has at least the following advantages: 1. This invention provides a two-color gradient watch strap and its preparation method. By setting a two-color gradient layer on the surface of the substrate layer and setting a covering layer on the outside of the two-color gradient layer, this invention can improve the decorative and durable properties of the watch strap while ensuring the softness and wearing comfort of the silicone watch strap.

[0018] 2. This invention improves the performance of the watch strap by reasonably adjusting the thickness of each layer in the gradient silicone watch strap; the thickness of the base layer can ensure the mechanical support and resilience of the main body of the watch strap; the thickness of the two-color gradient layer is conducive to ensuring the color display effect of the gradient pattern.

[0019] 3. This invention, by setting a coating layer on the outside of the two-color gradient layer and incorporating a vacuum degassing step and a step-by-step vulcanization process during the coating process, effectively reduces defects such as bubbles and voids within the coating layer and at the interlayer interfaces, thereby improving the density, uniformity, and overall structural stability of the coating layer. Preheating vulcanization facilitates the initial flow and adhesion of the rubber compound to the surface of the two-color gradient layer, while pressure vulcanization further enhances the density and interfacial bonding strength of the coating layer. After the coating layer of this invention covers the surface of the two-color gradient layer, it reduces the direct impact of external friction, sweat, dust, and cleaning processes on the two-color gradient layer, thereby reducing the risk of color fading, wear, contamination, and localized delamination of the gradient layer, and improving the appearance retention and service life of the watch strap during long-term wear.

[0020] 4. The present invention uses plasma activation treatment of the substrate layer, which can effectively improve the adhesion, coatability and printability of the substrate layer surface.

[0021] 5. This invention employs a gradient screen printing process combined with screen printing to prepare a two-color gradient layer. This allows for a continuous transition between two different colors of silicone ink, resulting in a gradient layer with advantages such as natural transition, uniform color, and good pattern consistency. The invention utilizes staged curing after printing, which helps to define the color boundaries of the two-color gradient layer, prevent color mixing, improve layer control, optimize gradient levels, enhance color layer adhesion and durability, adapt to dynamic use, and ensure consistent appearance of the watch strap. Subsequent UV light treatment further improves the surface condition, enhancing the surface adhesion, cleanliness, and feel of the finished watch strap. Attached Figure Description

[0022] Figure 1 This is an image of the watch strap obtained in Example 1. Detailed Implementation

[0023] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0024] This invention provides a two-color gradient silicone watch strap and its preparation method; the two-color gradient silicone watch strap includes a base layer, a two-color gradient layer disposed on the surface of the base layer, and a covering layer disposed on the surface of the two-color gradient layer; the colors of the base layer are all selected from one of transparent, semi-transparent, solid white, and semi-transparent black, and the colors of the covering layer are selected from one of transparent, semi-transparent, and semi-transparent black.

[0025] In this invention, the substrate layer is preferably formed by molding and vulcanizing liquid silicone raw material; the two-color gradient layer is preferably formed by screen printing two different colors of silicone ink; and the coating layer is preferably formed by secondary coating molding of liquid silicone raw material.

[0026] In this invention, the thickness of the substrate layer is preferably 1.55±0.2mm; the thickness of the two-color gradient layer is preferably 0.15±0.05mm; and the total thickness of the two-color gradient silicone watch strap is preferably 3-4mm.

[0027] The preparation method provided by this invention includes the following steps: S1. Preparation of the substrate layer; S2. Perform surface activation treatment on the substrate layer; S3. Screen print and cure the two-color gradient layer on the activated substrate layer surface; S4. A coating layer is formed by coating the surface of the two-color gradient layer; S5. After punching holes in the watch strap, post-processing is performed to obtain a two-color gradient silicone watch strap.

[0028] This invention improves the bonding strength between the two-color gradient layer and the substrate layer by activating the substrate layer and forming a coating layer on the outside of the two-color gradient layer, thereby enhancing the protective effect of the two-color gradient layer and the durability of the watch strap.

[0029] Regarding step S1: S1. Mix the liquid silicone raw material with the vulcanizing agent to obtain a rubber compound; place the rubber compound into a mold and cover the mold; send the mold into the machine for pressure; after the vulcanization time is reached, take out the product to obtain the base layer.

[0030] In this invention, the liquid silicone raw material can be a conventional addition-type liquid silicone rubber raw material in the art; the vulcanizing agent can be a conventional crosslinking component suitable for liquid silicone systems. The mixing method of the liquid silicone raw material and the vulcanizing agent can adopt a conventional mixing method in the art.

[0031] In this invention, the preferred vulcanization conditions are: temperature 130-140℃ and pressure 55-65 kg / cm². 2 The vulcanization time is 250-300 seconds. By controlling the vulcanization conditions within the above range, it is beneficial to obtain a matrix layer with stable dimensions, a smooth surface, and good mechanical properties.

[0032] In this invention, the resulting substrate layer preferably has the basic shape of the watch strap body and provides a bearing surface for the formation of the two-color gradient layer.

[0033] Regarding step S2: S2. Perform surface activation treatment on the substrate layer.

[0034] In this invention, the surface activation treatment is preferably plasma activation treatment. Preferably, the plasma is oxygen plasma; the treatment power is preferably 200-600W; and the treatment time is preferably 5-60s. Plasma activation treatment can increase the surface energy of the substrate layer, thereby improving the wettability and adhesion of the printed layer to the substrate layer surface.

[0035] Regarding step S3: S3. Using a gradient screen, a two-color gradient layer is printed on the surface of the activated substrate layer using screen printing technology, and then cured to form a two-color gradient layer.

[0036] In this invention, the two-color gradient layer is formed by two different colors of silicone ink. The silicone ink can be any conventional silicone ink suitable for screen printing.

[0037] In this invention, the preferred parameters of the gradient screen are: thickness 5μm, mesh size 420 mesh, and gradient length is 1 / 2 of the gradient screen length; the effective opening ratio at one end of the gradient screen is preferably 80-90%, and decreases continuously along the gradient direction, and the effective opening ratio variation range of adjacent gradient units is preferably 0.5%-3%.

[0038] In this invention, the preferred printing conditions are: 2 screens, printing pressure of 0.55-0.65 MPa, printing speed of 60-70 mm / s, 2 printing passes, and printing height of 3-5 mm.

[0039] In this invention, the curing process preferably includes: first treating at 80-120℃ for 2-10 minutes, and then treating at 165-170℃ for 20-30 minutes. By adopting a staged curing method, the film-forming stability and interlayer bonding stability of the two-color gradient layer can be improved.

[0040] In this invention, the thickness of the two-color gradient layer is preferably 0.15±0.05mm. Within this thickness range, it is beneficial to balance the color rendering effect, the gradient transition effect, and the stability of subsequent encapsulation molding.

[0041] Regarding step S4: S4. Place the substrate layer after printing the two-color gradient layer into the mold, cover it with the rubber material formed by mixing liquid silicone raw material and vulcanizing agent, and then perform vacuum degassing and vulcanization to form a watch strap blank with a coating layer.

[0042] In this invention, the coating layer is preferably made from liquid silicone raw material. The liquid silicone raw material can be the same as or compatible with the substrate layer.

[0043] In this invention, the preferred vacuum exhaust conditions are: vacuum degree -0.04~-0.09 MPa, time 2-6 min. By incorporating a vacuum exhaust step, defects such as bubbles and voids can be reduced inside the coating layer and at the interface between the coating layer and the two-color gradient layer.

[0044] In this invention, the vulcanization process preferably includes: preheating vulcanization at 120-130℃ for 40-60 seconds, then raising the temperature to 130-140℃, and maintaining a temperature of 110-125 kg / cm². 2 Continue vulcanization under pressure for 210-240 seconds, with the total vulcanization time controlled at 250-300 seconds. Preheating vulcanization facilitates the initial flow of the rubber compound and its adhesion to the surface of the two-color gradient layer, while subsequent pressure vulcanization helps improve the density of the coating layer and the interlayer bonding strength.

[0045] In this invention, the resulting coating layer covers the outside of the two-color gradient layer, which can protect the two-color gradient layer and reduce the direct effects of external friction, sweat, dust and the washing process on the gradient layer.

[0046] Regarding step S5: S5. Post-process the watch strap blank with the coating layer to obtain a two-color gradient silicone watch strap.

[0047] In this invention, the post-processing preferably includes UV light irradiation treatment; the UV light irradiation treatment conditions are preferably: ultraviolet light with a wavelength of 365nm, a transmission speed of 0.2-0.3m / min, a light height of 60-65mm, a light intensity of 100%, and irradiation is applied to both the front and back sides once.

[0048] Post-processing can further improve the surface condition of the watch strap, enhancing the appearance consistency and reliability of the finished watch strap.

[0049] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention. Example 1

[0050] A method for preparing a two-tone gradient silicone watch strap includes the following steps: S1. Mix transparent liquid silicone raw material (R4000 / 60A, Wujiang General Silicone Co., Ltd.) with vulcanizing agent (PT2) evenly to obtain a rubber compound; place the rubber compound into the watch strap base mold, close the mold, and send it to the machine for curing at 135℃ and 60kg / cm². 2 After vulcanization for 280 seconds under certain conditions, a base layer with a thickness of 1.55 mm was obtained. S2. The substrate layer surface is activated using oxygen plasma at a power of 400W for 20 seconds. The activated substrate layer surface is then cleaned with isopropanol and dried with hot air at 55°C for 3 minutes. S3. Two gradient screen printing plates (5μm thick, 420 mesh, gradient length half the screen length, 85% effective opening rate at one end, continuously decreasing along the gradient direction, with an effective opening rate variation of 1.5% between adjacent gradient units) are used for two-color gradient screen printing on the activated substrate surface. Specifically, one gradient screen is used first, and silicone ink (HC-K11127A, Dongguan Huachen Silicone Technology Co., Ltd.) is used for one printing pass. The printing conditions are: printing pressure 0.60MPa. The printing speed was 65mm / s, the number of printing passes was 2, and the printing height was 4mm. The first printing was treated at 100℃ for 5 minutes, and then cured at 168℃ for 25 minutes. Then, the same printing conditions were used, and silicone ink (HC-K11141A, Dongguan Huachen Silicone Technology Co., Ltd.) was used for a second printing. The gradient direction of the second printing was opposite to that of the first printing. Then, the printing was treated at 100℃ for 5 minutes and then cured at 168℃ for 25 minutes to obtain a two-color gradient layer with a thickness of 0.15mm. S5. Place the substrate layer printed with the two-color gradient layer into the mold, cover its surface with a rubber compound formed by mixing transparent liquid silicone raw material (R4000 / 60A, Wujiang General Silicone Co., Ltd.) and vulcanizing agent (PT2), and then perform vacuum degassing at a vacuum degree of -0.07MPa for 4 minutes; after vacuum degassing, preheat vulcanize at 125℃ for 50 seconds, then raise the temperature to 135℃, and vulcanize at 118kg / cm². 2Continue vulcanization under pressure for 220 seconds to form a watch strap with a coating layer; S6. After punching the above-mentioned watch strap, perform UV light treatment. The UV light treatment conditions are: ultraviolet light with a wavelength of 365nm, transmission speed of 0.25m / min, light height of 62mm, light intensity of 100%, and irradiate both the front and back once to obtain a finished product of a two-color gradient silicone watch strap with a thickness of 3.4mm.

[0051] The appearance of the watch strap produced in this embodiment is as follows: Figure 1 As shown, Figure 1 (a) shows the front of the watch strap, and (b) shows the back of the watch strap. From Figure 1 As can be seen, the watch strap prepared by this invention has a natural gradient effect, good color rendering, and a natural transition at the connection point of the two colors. Example 2

[0052] A method for preparing a two-tone gradient silicone watch strap includes the following steps: S1. Mix transparent liquid silicone raw material (R4000 / 60A, Wujiang General Silicone Co., Ltd.) with vulcanizing agent (PT2) evenly to obtain a rubber compound; place the rubber compound into the watch strap base mold, close the mold, and send it to the machine for curing at 135℃ and 60kg / cm². 2 After vulcanization for 280 seconds under certain conditions, a base layer with a thickness of 1.55 mm was obtained. S2. The substrate layer surface is activated using oxygen plasma at a power of 300W for 10s. The activated substrate layer surface is then cleaned with isopropanol and dried with hot air at 55℃ for 3min. S3. Two gradient screen printing plates (5μm thick, 420 mesh, gradient length half the screen length, 85% effective opening rate at one end, continuously decreasing along the gradient direction, with an effective opening rate variation of 1.5% between adjacent gradient units) are used for two-color gradient screen printing on the activated substrate surface. Specifically, one gradient screen is used first, and silicone ink (HC-K11127A, Dongguan Huachen Silicone Technology Co., Ltd.) is used for one printing pass. The printing conditions are: printing pressure of 0.58 MPa. a. The printing speed is 62mm / s, the number of printing times is 2, and the printing height is 4mm. First, it is treated at 90℃ for 4min, and then cured at 167℃ for 22min. Then, the same printing conditions are used, and silicone ink (HC-K11141A, Dongguan Huachen Silicone Technology Co., Ltd.) is used for a second printing. The gradient direction of the second printing is opposite to that of the first printing. Then, it is treated at 90℃ for 4min and then cured at 167℃ for 22min to obtain a two-color gradient layer with a thickness of 0.15mm. S5. Place the substrate layer printed with the two-color gradient layer into the mold, cover its surface with a rubber compound formed by mixing transparent liquid silicone raw material (R4000 / 60A, Wujiang General Silicone Co., Ltd.) and vulcanizing agent (PT2), and then perform vacuum degassing at a vacuum degree of -0.05MPa for 3 minutes; after vacuum degassing, preheat vulcanize at 122℃ for 45 seconds, then raise the temperature to 132℃, and vulcanize at 112kg / cm². 2 Continue vulcanization under pressure for 230 seconds to form a watch strap with a coating layer; S6. After punching the above-mentioned watch strap, perform UV light treatment. The UV light treatment conditions are: conveying speed of 0.25m / min, light height of 62mm, light intensity of 100%, and irradiate both the front and back once to obtain a finished two-color gradient silicone watch strap with a thickness of 3.4mm. Example 3

[0053] A method for preparing a two-tone gradient silicone watch strap includes the following steps: S1. Mix transparent liquid silicone raw material (R4000 / 60A, Wujiang General Silicone Co., Ltd.) with vulcanizing agent (PT2) evenly to obtain a rubber compound; place the rubber compound into the watch strap base mold, close the mold, and send it to the machine for curing at 135℃ and 60kg / cm². 2 After vulcanization for 280 seconds under certain conditions, a base layer with a thickness of 1.55 mm was obtained. S2. The substrate layer surface is activated using oxygen plasma at a power of 300W for 10s. The activated substrate layer surface is then cleaned with isopropanol and dried with hot air at 55℃ for 3min. S3. Two gradient screen printing plates (5μm thick, 420 mesh, gradient length half the screen length, 88% effective opening rate at one end, continuously decreasing along the gradient direction, with a 2% variation in effective opening rate between adjacent gradient units) are used for two-color gradient screen printing on the activated substrate surface. Specifically, one gradient screen is used first, and silicone ink (HC-K11127A, Dongguan Huachen Silicone Technology Co., Ltd.) is used for one printing pass. The printing conditions are: printing pressure of 0.58MPa. The printing speed was 62mm / s, the number of printing passes was 2, and the printing height was 4mm. The first printing was treated at 90℃ for 4 minutes, and then cured at 167℃ for 22 minutes. Then, the same printing conditions were used, and silicone ink (HC-K11141A, Dongguan Huachen Silicone Technology Co., Ltd.) was used for a second printing. The gradient direction of the second printing was opposite to that of the first printing. Then, the printing was treated at 90℃ for 4 minutes and then cured at 167℃ for 22 minutes to obtain a two-color gradient layer with a thickness of 0.15mm. S5. Place the substrate layer printed with the two-color gradient layer into the mold, cover its surface with a rubber compound formed by mixing transparent liquid silicone raw material (R4000 / 60A, Wujiang General Silicone Co., Ltd.) and vulcanizing agent (PT2), and then perform vacuum degassing at a vacuum degree of -0.08MPa for 5 minutes; after vacuum degassing, preheat vulcanize at 128℃ for 60 seconds, then raise the temperature to 138℃ and vulcanize at 120kg / cm². 2 Continue vulcanization under pressure for 215 seconds to form a watch strap with a coating layer; S6. After punching the above-mentioned watch strap, perform UV light treatment. The UV light treatment conditions are: ultraviolet light with a wavelength of 365nm, transmission speed of 0.25m / min, light height of 62mm, light intensity of 100%, and irradiate both the front and back once to obtain a finished product of a two-color gradient silicone watch strap with a thickness of 3.4mm.

[0054] Comparative Example 1 The difference between this example and Example 1 is that the substrate layer is not subjected to plasma treatment, but the other operations are the same as in Example 1.

[0055] Comparative Example 2 The difference between this example and Example 1 is that: in step S5, vacuum degassing is not performed, and the coating layer is prepared directly by coating vulcanization. Other operations are the same as in Example 1.

[0056] Comparative Example 3 The difference between this example and Example 1 is that in step S5, the preheating vulcanization step is not used, and the vulcanization is completed directly at 135°C. The other operations are the same as in Example 1.

[0057] The performance of the watch straps of Examples 1-3 and Comparative Examples 1-3 were tested.

[0058] 1. Abrasion resistance test: The tests were conducted in accordance with GB / T 33725-2017 "Watch cases and their accessories - Abrasion resistance, scratch and impact resistance tests" and QB / T 8190-2025 "Watch cases and their accessories - Reciprocating friction test". Test method: The TABER 5135 abrasion tester was used, with a CS-10 grinding wheel, a load of 500g, and 1000 friction cycles. Evaluation criteria: Observe the surface wear of the two-color gradient layer and rate it according to the following standards: Grade I: No obvious wear, pattern is clear and complete; Grade II: Slight wear, pattern still legible; Grade III: Obvious wear, pattern parts blurred; Grade IV: Severe wear and tear, pattern is unrecognizable or has fallen off.

[0059] 2. Bending fatigue resistance test The bending fatigue performance was tested in accordance with the standards QB / T 4887-2015 "Thermoplastic Polyurethane Watch Straps" and QB / T 2540-2023 "Leather Watch Straps". Test method: Bending fatigue testing machine was used, with a bending angle of ±90°, a frequency of 60 times / minute, and 5000 cycles. Evaluation criteria: Observe whether the watch strap has cracks, peeling, curling edges, etc., and record the number of bends when obvious defects are found.

[0060] 3. Weather resistance test: Conducted according to standard ISO 4892-3 "Plastics - Laboratory light source exposure methods - Part 3: Ultraviolet fluorescent lamps"; Test method: A UV aging test chamber was used, with UVB-313 lamps and an irradiance of 0.68 W / m². 2 Irradiated at 50℃ for 500 hours; Evaluation metric: Color difference ΔE value measured before and after testing (using CIE Lab color difference formula). ΔE≤3.0 is considered acceptable.

[0061] 4. Sweat resistance test: According to standard ISO 3160-2 "Watches - Cases and accessories - Gold alloy coatings - Part 2: Tests for purity, thickness, corrosion resistance and adhesion" and the test specifications for sweat corrosion resistance of sports equipment; Test method: Artificial sweat formula: sodium chloride 20g / L, lactic acid 10g / L, urea 5g / L, pH=5.5 (simulating acidic sweat); Test conditions: The watch strap was completely immersed in 40°C sweat for 168 hours; Evaluation indicators: Observe whether the two-color gradient layer shows phenomena such as bubbling, peeling, and color change; Color change grade: Evaluate the color change grade according to GB / T251-2008 "Textiles - Test for Color Fastness - Gray Scale for Staining" (Grade 5 is the best, Grade 1 is the worst).

[0062] The test results are shown in Table 1.

[0063] Table 1 ; As can be seen from the test results in Table 1, the two-color gradient silicone watch straps obtained in Examples 1-3 of the present invention exhibit outstanding performance in terms of wear resistance, bending fatigue resistance, aging resistance, and sweat resistance. Moreover, their overall performance is significantly better than that of Comparative Examples 1-3, indicating that the present invention effectively improves the comprehensive performance of the two-color gradient silicone watch strap by optimizing the watch strap composition and manufacturing process.

[0064] In the abrasion resistance test, the watch straps of Examples 1-3 all achieved Grade I after 1000 cycles of friction, indicating that the two-color gradient layer in the watch strap did not show significant wear, and the pattern remained clear and intact. In contrast, the two-color gradient layer in the comparative examples was more prone to wear, blurring, and even localized damage under friction. The abrasion resistance test results demonstrate that this invention, through surface activation treatment of the substrate layer and the application of a coating layer on the outside of the two-color gradient layer, effectively enhances the bond between the two-color gradient layer and the substrate layer, and reduces direct damage to the two-color gradient layer from external friction.

[0065] In the bending fatigue performance test, Examples 1-3 showed no obvious defects after 5000 bends, indicating that the watch strap prepared by the present invention can maintain good structural integrity and interlayer bonding stability under repeated bending conditions; while the number of bends when obvious defects appeared in Comparative Examples 1-3 was significantly lower than that in Examples 1-3. The above results show that the present invention improves the interfacial bonding strength between the two-color gradient layer and the substrate layer by activating the substrate layer, and effectively protects the two-color gradient layer through the coating layer, thereby effectively reducing the risk of defects such as peeling, warping, and cracking during the bending process of the watch strap. Comparative Example 1 did not undergo plasma treatment, and the bending life of the watch strap was also significantly reduced, indicating that surface activation treatment can effectively improve the coatability, printability, and adhesion of the substrate layer surface; the results of Comparative Examples 2 and 3 show that vacuum degassing and preheating vulcanization are of great significance for improving the density of the coating layer, reducing interfacial defects, and improving interlayer adhesion.

[0066] In the aging resistance test, the color difference ΔE of the watch straps of Examples 1-3 after UV aging was 1.8, 2.1, and 1.9, respectively, all less than 3.0, indicating that the watch straps obtained by the present invention still have good color stability and appearance retention under UV irradiation conditions; while the ΔE of Comparative Examples 1-4 was higher than that of Examples 1-3. The above results show that the coating layer and corresponding molding process used in the present invention can effectively reduce the adverse effects of UV aging on the two-color gradient layer, thereby improving the weather resistance of the watch strap.

[0067] In the sweat resistance test, the color change level of the watch straps in Examples 1-3 was all level 5, indicating that after immersion in artificial sweat for 168 hours, the two-color gradient layer did not show obvious bubbling, peeling, or color change, demonstrating excellent sweat resistance. In contrast, the watch straps in Comparative Examples 1-3 were significantly inferior to those in Examples 1-3. These results demonstrate that the present invention enhances interfacial adhesion through activation treatment of the substrate layer, isolates sweat erosion through the coating layer, and improves the density and integrity of the coating layer through vacuum degassing and stepwise vulcanization, thereby effectively improving the watch strap's resistance to sweat corrosion under long-term wear conditions.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A two-tone gradient silicone watch strap, characterized in that, The device includes a substrate layer, a two-color gradient layer disposed on the surface of the substrate layer, and a covering layer disposed on the surface of the two-color gradient layer; the thickness of the substrate layer is 1.55±0.2mm, the thickness of the two-color gradient layer is 0.15±0.05mm, and the thickness of the two-color gradient silicone strap is 3-4mm; the substrate layer and the covering layer are made of liquid silicone raw material, and the two-color gradient layer is made by screen printing two different colors of silicone ink; the colors of the substrate layer are selected from one of transparent, semi-transparent, solid white, and semi-transparent black, and the colors of the covering layer are selected from one of transparent, semi-transparent, and semi-transparent black.

2. The method for preparing a two-tone gradient silicone watch strap according to claim 1, characterized in that, Includes the following steps: S1. Mix the liquid silicone raw material with the vulcanizing agent to obtain the rubber compound. Place the rubber compound into the mold and cover the mold. Press the mold into the machine and remove the product after the vulcanization time is reached to obtain the base layer. S2. Perform surface activation treatment on the substrate layer; S3. Using a gradient screen, a two-color gradient layer is printed on the surface of the activated substrate layer using screen printing technology, and then cured to form a two-color gradient layer. S4. Place the substrate layer after printing the two-color gradient layer into the mold, cover it with the rubber compound made of liquid silicone raw material and vulcanizing agent, and then perform vacuum degassing and vulcanization to form a watch strap with a coating layer. S5. After punching holes in the watch strap covered with silicone coating, perform post-processing to obtain a two-color gradient silicone watch strap.

3. The method for preparing a two-tone gradient silicone watch strap according to claim 2, characterized in that, In step S1, the conditions for the vulcanization are: temperature 130-140°C, pressure 55-65 kg / cm 2 , vulcanization time 250-300 s.

4. The method for preparing a two-tone gradient silicone watch strap according to claim 2, characterized in that, In step S2, the surface activation treatment is a plasma activation treatment, the power of the plasma activation treatment is 200-600W, the treatment time is 5-60s, and the type of plasma is oxygen plasma.

5. The method for preparing a two-tone gradient silicone watch strap according to claim 2, characterized in that, In step S3, the parameters of the gradient screen are: thickness: 5μm, mesh size: 420 mesh, and gradient length of the gradient screen: 1 / 2 of the length of the gradient screen. The effective aperture ratio at one end of the gradient screen is 80-90%, and the effective aperture ratio of the gradient screen continuously decreases along the gradient direction. The effective aperture ratio of adjacent gradient units varies by 0.5%-3%.

6. The method for preparing a two-tone gradient silicone watch strap according to claim 2, characterized in that, In step S3, the printing conditions are as follows: number of screens: 2, printing pressure: 0.55-0.65MPa, printing speed: 60-70mm / s, number of printing passes: 2, printing height: 3-5mm; curing is performed after each printing.

7. The method for preparing a two-tone gradient silicone watch strap according to claim 2, characterized in that, In step S3, the curing process includes: first treating at 80-120℃ for 2-10 minutes, and then treating at 165-170℃ for 20-30 minutes.

8. The method for preparing a two-tone gradient silicone watch strap according to claim 3, characterized in that, In step S4, the vacuum exhaust process includes: -0.04~-0.09MPa, for a time of 2-6 minutes.

9. The method for preparing a two-tone gradient silicone watch strap according to claim 3, characterized in that, In step S4, the vulcanization process includes: first, preheating vulcanization at 120-130℃ for 40-60 seconds, then raising the temperature to 130-140℃, and maintaining a pressure of 110-125 kg / cm². 2 Continue vulcanization under pressure for 210-240 seconds, with the total vulcanization time controlled at 250-300 seconds.

10. The method for preparing a two-tone gradient silicone watch strap according to claim 3, characterized in that, In step S5, the post-processing includes UV light irradiation; the conditions for UV light irradiation are: ultraviolet light with a wavelength of 365nm, a transmission speed of 0.2-0.3m / min, an irradiation height of 60-65mm, an irradiation intensity of 100%, and irradiation once on each side.

Images