Double-color injection molding process and mold for silica gel product

Abstract

The invention provides a double-color injection molding process and mold for a silica gel product, and relates to the technical field of injection molding. By optimizing a mold temperature control system and injection parameters, gradient vulcanization of the two silica gels in the mold is achieved, the two silica gels form an interpenetrating network structure on a bonding interface, the bonding strength is improved compared with that of a traditional secondary vulcanization process, the problems of layering, cracking and the like of a product in the using process are reduced, meanwhile, an integrated injection molding mode is adopted, and the product quality is improved. The secondary positioning link of the base piece is omitted, the size precision and the appearance flatness of the two-color combination position are improved, and the appearance quality of the product is improved.

Description

Technical Field

[0001] This invention relates to the field of injection molding technology, and more specifically, to a two-color injection molding process and mold for silicone products. Background Technology

[0002] Silicone products are widely used in electronics, medical, automotive, and daily necessities due to their excellent high temperature resistance, corrosion resistance, elasticity and biocompatibility. As the market demand for integrated functions and diversified appearance of silicone products continues to increase, single-color or single-performance silicone products can no longer meet the actual application scenarios, and the demand for two-color or multi-color silicone products is growing. Currently, the molding processes for two-color silicone products mainly include secondary vulcanization molding and traditional two-color injection molding. The secondary vulcanization molding process requires first molding a silicone substrate of the first color using injection molding or compression molding. After the substrate is fully vulcanized, it is removed and placed in another mold for positioning. The second color of silicone is then injected for secondary vulcanization. This process has significant drawbacks: firstly, the substrate undergoes two high-temperature treatments during the two vulcanization processes, which can easily lead to substrate aging, and the shrinkage rates of the two vulcanizations are difficult to match precisely, easily resulting in cracking and delamination of the product; secondly, deviations are prone to occur during the secondary positioning of the substrate, leading to low precision at the two-color joint and poor surface smoothness. Furthermore, the process is cumbersome and has a long production cycle. Therefore, we propose an improvement, namely a two-color injection molding process and mold for silicone products. Summary of the Invention

[0003] This invention provides a two-color injection molding process and mold for silicone products, comprising the following steps: S1. Raw material pretreatment: Select two silicone raw materials of different colors or properties, and mix each silicone raw material with a vulcanizing agent at a mass ratio of 100:1-100:3. Stir for 10-15 minutes at a speed of 300-500 r / min and a temperature of 25-35℃ to obtain uniform silicone mixture A and silicone mixture B. S2. Mold preparation: An injection mold is used. The injection mold includes a fixed mold, a moving mold, and two independent cavities corresponding to silicone compound A and silicone compound B, respectively. The two cavities are connected by a flow channel, and a zoned temperature control system is set in the mold to preset the temperature of cavity A to 120-140℃ and the temperature of cavity B to 100-120℃. S3, One-time injection: Add silicone mixture A to the first barrel of the two-color injection molding machine. The barrel temperature is controlled at 50-70℃. Inject silicone mixture A into cavity A through the injection system at a pressure of 80-100MPa and hold the pressure for 10-15 seconds. S4. Secondary injection: Keep the mold closed and add silicone mixture B to the second barrel of the two-color injection molding machine. The barrel temperature is controlled at 45-65℃. The silicone mixture B is injected into cavity B through the guide channel at a pressure of 70-90MPa by the injection system, so that the silicone mixture B and the incompletely vulcanized silicone mixture A in cavity A fuse at the bonding interface. Hold the pressure for 15-20 seconds. S5. Vulcanization and Demolding: Raise the overall temperature of the mold to 150-170℃, hold for 20-30 seconds for vulcanization, and after vulcanization, cool the mold to 50-60℃, open the mold and remove the two-color silicone product.

[0004] As a preferred technical solution of this application, the vulcanizing agent in step S1 is benzoyl peroxide or 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, and the mixing process of the silicone raw material and the vulcanizing agent is carried out in a vacuum environment with a vacuum degree of -0.08 to -0.1 MPa.

[0005] As a preferred technical solution of this application, the partitioned temperature control system in step S2 includes heating tubes and temperature sensors corresponding to cavity A and cavity B respectively. The detection accuracy of the temperature sensor is ±0.5℃, and the inner diameter of the flow channel is 2-5mm and the length is 5-10mm.

[0006] As a preferred technical solution of this application, the injection speed of the injection system in steps S3 and S4 is 50-80 mm / s, and the injection process adopts a segmented injection method, with the first segment injection speed being 50-60 mm / s and the second segment injection speed being 70-80 mm / s.

[0007] As a preferred technical solution of this application, the cooling method of the mold in step S5 is water cooling, the cooling water flow rate is 3-5L / min, and after vulcanization, a segmented cooling method is adopted, first cooling the mold temperature from 150-170℃ to 100-120℃, holding it for 5-10 seconds, and then cooling it to 50-60℃.

[0008] As a preferred technical solution of this application, the hardness difference between the silicone mixture A and the silicone mixture B is Shore A 10°-30°, and one of the silicone mixtures is conductive silicone. The amount of conductive filler is calculated according to the formula M1=M2×ω, where M1 is the mass of conductive filler, M2 is the total mass of conductive silicone mixture, and ω is the mass fraction of conductive filler, with ω taking a value of 5%-10%. The conductive filler is carbon black or silver powder.

[0009] As a preferred technical solution of this application, the injection pressure in step S3 is calculated according to the formula P1=P2×KL; Where P1 is the primary injection pressure, P2 is the basic injection pressure of silicone mixture A (60-80 MPa), and KL is the pressure correction coefficient (1.1-1.3). And the injection volume satisfies V1=V2×(1+δ); Where V1 is the injection volume per shot, V2 is the cavity A volume, and δ is the shrinkage rate of 5%-10%.

[0010] As a preferred technical solution of this application, the secondary injection pressure in step S4 is determined according to the formula P3=P4×KQ; Where P3 is the secondary injection pressure, P4 is the basic injection pressure of silicone mixture B (50-70 MPa), and KQ is the pressure correction coefficient (1.2-1.4). The silicone flow velocity v in the guide channel satisfies v=Q / S, where Q is the secondary injection flow rate, S is the cross-sectional area of ​​the guide channel, and v is controlled within 0.1-0.3m / s.

[0011] As a preferred technical solution of this application, the vulcanization holding time in step S5 is calculated according to the formula T1=h×kT; Where T1 is the vulcanization holding time, h is the maximum wall thickness of the product in mm, and kT is the time coefficient 20-30s / mm. When the calculated value is less than 20s, take 20s; when it is greater than 30s, take 30s. Cooling time is calculated using the formula T2=(T3-T4)×C; Where T2 is the cooling time, T3 is the vulcanization temperature (150-170℃), T4 is the demolding temperature (50-60℃), and C is the cooling coefficient (0.8-1.2s / ℃).

[0012] A two-color injection molding mold for silicone products, used to realize the two-color injection molding process of silicone products, includes a fixed mold, a moving mold, and two independent cavities corresponding to silicone mixture A and silicone mixture B respectively, and the two cavities are connected by a guide channel.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: In the scheme of this application: 1. This application achieves gradient vulcanization of two types of silicone in the mold by optimizing the mold temperature control system and injection parameters, so that the two types of silicone form an interpenetrating network structure at the bonding interface, which improves the bonding strength compared with the traditional secondary vulcanization process and reduces problems such as delamination and cracking in the product during use. At the same time, the integrated injection molding method eliminates the secondary positioning of the base part, resulting in high dimensional accuracy at the two-color bonding point, improved appearance flatness, and improved product appearance quality. 2. This application adopts a two-color injection molding machine for integrated molding, which simplifies the traditional two-stage vulcanization process of two vulcanizations and two positioning processes into a one-stage injection and one-stage vulcanization process. The production cycle of a single part is shortened and the production efficiency is improved. At the same time, by optimizing the barrel heating method and the injection system, the blockage phenomenon is effectively avoided, the equipment failure rate is reduced, and the continuous and stable operation of the production line is further guaranteed.

[0014] 3. On the one hand, the integrated molding process reduces the number of molds used, eliminating the need for separate design of base component molding molds and reducing mold manufacturing costs; on the other hand, the shortened production cycle and reduced equipment failure rate reduce labor and equipment maintenance costs, and improve the product qualification rate. Attached Figure Description

[0015] Figure 1 The flow chart of the two-color injection molding process for silicone products provided in this application; Figure 2 This is a schematic diagram of the structure of the two-color injection molding mold for silicone products provided in this application. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0017] It should be noted that, unless otherwise specified, the embodiments and features and technical solutions in the present invention can be combined with each other.

[0018] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0019] Example 1, please refer to Figure 1 A two-color injection molding process and mold for silicone products, comprising the following steps: S1. Raw Material Pretreatment: Select two silicone raw materials of different colors or properties. Mix each silicone raw material with a vulcanizing agent at a mass ratio of 100:1-100:3. Stir for 10-15 minutes at a speed of 300-500 r / min and a temperature of 25-35℃ to obtain uniform silicone mixture A and silicone mixture B. The vulcanizing agent ratio of 100:1-100:3 conforms to the optimal ratio range for silicone vulcanization, ensuring sufficient vulcanization without causing brittleness due to excessive vulcanizing agent or incomplete vulcanization due to insufficient vulcanizing agent. A speed of 300-500 r / min can create suitable shear force, allowing the vulcanizing agent to be evenly dispersed in the silicone, while avoiding excessive bubbles generated by excessive speed. 25-35℃ is the suitable temperature for silicone mixing, which can prevent the mixing resistance from increasing and uneven mixing due to excessively low temperature, or the silicone from undergoing premature partial vulcanization reaction due to excessively high temperature. S2. Mold Preparation: An injection mold is used, comprising a fixed mold, a moving mold, and two independent cavities corresponding to silicone compound A and silicone compound B, respectively. The two cavities are connected by a flow channel, and a zoned temperature control system is installed inside the mold, presetting the temperature of cavity A to 120-140℃ and the temperature of cavity B to 100-120℃. The two independent cavities can respectively adapt to the molding requirements of the two compounds, avoiding mutual interference. The flow channel provides a way for compound B to enter cavity B and come into contact with compound A in cavity A. The zoned temperature control system presets cavity A to 120-140℃ and cavity B to 100-120℃. This temperature range meets the flow molding requirements of silicone injection molding and keeps compound A in cavity A in an incompletely vulcanized state, which is convenient for fusion with the subsequently injected compound B. At the same time, it avoids the compound A from becoming too vulcanized prematurely and unable to fuse due to excessively high temperature, or the compound from becoming too fluid and incompletely filled due to excessively low temperature. S3. Single Injection: Add silicone compound A to the first barrel of the two-color injection molding machine. The barrel temperature is controlled at 50-70℃. Inject silicone compound A into cavity A through the injection system at a pressure of 80-100MPa and hold the pressure for 10-15 seconds. The barrel temperature of 50-70℃ can maintain the good fluidity of compound A, which is convenient for injection and filling, while avoiding premature vulcanization due to excessive temperature. The injection pressure of 80-100MPa can overcome the flow resistance of the compound, ensuring that it quickly and fully fills all corners of cavity A. The 10-15 second holding time can compensate for the shrinkage of compound A in cavity A, make up for the volume shrinkage during the cooling process, and reduce defects such as shrinkage cavities and depressions. S4. Secondary Injection: Keeping the mold closed, add silicone mixture B to the second barrel of the two-color injection molding machine. Control the barrel temperature at 45-65℃. Inject silicone mixture B into cavity B through the guide channel at a pressure of 70-90MPa using the injection system. This allows silicone mixture B to fuse with the incompletely vulcanized silicone mixture A in cavity A at the interface. Hold the pressure for 15-20 seconds. The 45-65℃ second barrel temperature is suitable for the flowability requirements of mixture B and forms a reasonable temperature gradient with cavity A, facilitating interface fusion. The 70-90MPa injection pressure ensures that mixture B smoothly fills cavity B through the guide channel without deforming the already formed mixture A in cavity A due to excessive pressure. The 15-20 second holding time not only compensates for the shrinkage of mixture B in cavity B but also provides sufficient time for the interface fusion of the two silicone materials, enhancing the interfacial bonding force. S5. Vulcanization and Demolding: Raise the overall temperature of the mold to 150-170℃ and hold for vulcanization for 20-30 seconds. After vulcanization, cool the mold to 50-60℃ and open the mold to remove the two-color silicone product. 150-170℃ is the optimal temperature range for silicone vulcanization, which allows silicone molecules to fully cross-link, forming a stable structure and improving the mechanical properties of the product, such as hardness and strength. The 20-30 second holding time for vulcanization ensures that the vulcanization reaction is fully carried out, avoiding insufficient vulcanization that would lead to a decrease in product performance. Demolding at 50-60℃ lowers the product temperature, increases hardness, and makes it less prone to deformation or damage due to demolding force, while also preventing burns to operators from excessively high temperatures.

[0020] Furthermore, in step S1, the vulcanizing agent is benzoyl peroxide or 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, and the mixing process of the silicone raw material and the vulcanizing agent is carried out in a vacuum environment with a vacuum degree of -0.08 to -0.1 MPa. Benzoyl peroxide and 2,5-dimethyl-2,5-di-tert-butylperoxyhexane are highly efficient vulcanizing agents for silicone vulcanization. They have suitable decomposition temperatures and can stably release free radicals during silicone molding and vulcanization, promoting efficient vulcanization reaction. The vacuum environment can completely remove the air generated during the mixing process and the trace bubbles contained in the silicone raw material, avoiding bubbles remaining in the mixture and causing defects such as bubbles and pinholes in the molded product, thus improving the density and surface smoothness of the product.

[0021] Furthermore, in step S2, the zoned temperature control system includes heating tubes and temperature sensors corresponding to cavity A and cavity B respectively. The temperature sensor has a detection accuracy of ±0.5℃, and the inner diameter of the flow channel is 2-5mm and the length is 5-10mm.

[0022] Furthermore, in steps S3 and S4, the injection speed of the injection system is 50-80 mm / s, and a segmented injection method is adopted during the injection process. The first segment injection speed is 50-60 mm / s, and the second segment injection speed is 70-80 mm / s. In the segmented injection method, the low-speed injection of 50-60 mm / s in the first segment allows the mixture to enter the cavity smoothly, avoiding the air bubbles generated by the high-speed injection, and preventing the mixture from having too much impact on the cavity wall and causing mold breakage. The high-speed injection of 70-80 mm / s in the second segment can quickly fill the remaining space in the cavity, reduce the cooling time of the mixture in the cavity, avoid incomplete filling due to excessive cooling, and achieve stable and efficient filling.

[0023] Furthermore, in step S5, the mold is cooled by water with a water flow rate of 3-5 L / min. After vulcanization, a segmented cooling method is adopted. First, the mold temperature is cooled from 150-170℃ to 100-120℃, held for 5-10 seconds, and then cooled to 50-60℃. Water cooling has high heat transfer efficiency, and the cooling water flow rate of 3-5 L / min can ensure sufficient cooling capacity and quickly remove the heat from the mold. The segmented cooling method first lowers the temperature to 100-120℃ and holds it for 5-10 seconds, which can make the internal and external temperatures of the product uniform and reduce the internal stress caused by the temperature gradient. Then, it is cooled to 50-60℃ to avoid cracking and deformation caused by uneven shrinkage due to direct rapid cooling, thus improving the dimensional stability of the product.

[0024] Furthermore, the hardness difference between silicone compound A and silicone compound B is Shore A 10°-30°, and one of the silicone compounds is conductive silicone. The amount of conductive filler is calculated according to the formula M1=M2×ω, where M1 is the mass of conductive filler, M2 is the total mass of conductive silicone compound, and ω is the mass fraction of conductive filler, with a value of 5%-10%. The conductive filler is carbon black or silver powder. The Shore A hardness difference of 10°-30° allows different parts of the product to meet different hardness requirements, such as one side being soft for bonding and the other side being harder for support. Carbon black or silver powder is a highly efficient conductive filler, and a mass fraction of 5%-10% ensures that the conductive silicone has good conductivity without reducing the flexibility and processing performance of the silicone due to excessive filler. The precise calculation of the amount using the formula avoids filler waste or insufficiency, allowing the product to be applied to scenarios that require conductivity and different parts have different hardness requirements, such as conductive seals for electronic devices.

[0025] Furthermore, in step S3, the injection pressure is calculated using the formula P1 = P2 × KL; Where P1 is the initial injection pressure, P2 is the base injection pressure of silicone compound A (60-80 MPa), and KL is the pressure correction coefficient (1.1-1.3). The base injection pressure, combined with the correction coefficient of 1.1-1.3, can be precisely adjusted according to the actual fluidity of compound A, the complexity of the cavity, and other factors to avoid incomplete filling due to insufficient pressure or cavity deformation due to excessive pressure. And the injection volume satisfies V1=V2×(1+δ); Where V1 is the injection volume per shot, V2 is the cavity A volume, and δ is the shrinkage rate of 5%-10%; the injection volume is calculated by adding 5%-10% shrinkage rate to the cavity volume, which can accurately meet the filling and shrinkage requirements, avoid problems such as insufficient injection volume leading to material shortage or excessive injection volume leading to waste and flash, etc. The quantitative control by formula can ensure that the injection parameters of each batch of products are consistent, and improve the stability of product quality.

[0026] Furthermore, the secondary injection pressure in step S4 is determined according to the formula P3=P4×KQ; Where P3 is the secondary injection pressure, P4 is the basic injection pressure of silicone compound B (50-70MPa), and KQ is the pressure correction coefficient (1.2-1.4). The basic injection pressure, combined with the correction coefficient of 1.2-1.4, allows for precise adjustment of the secondary injection pressure based on the characteristics of compound B and the resistance of the flow channel, ensuring smooth filling. The silicone flow rate v in the guide channel satisfies v=Q / S, where Q is the secondary injection flow rate and S is the cross-sectional area of ​​the guide channel, and v is controlled within 0.1-0.3 m / s. The flow rate of 0.1-0.3 m / s in the guide channel can ensure that the mixture B can quickly pass through the channel and fuse with the mixture A, while avoiding the mixture splashing and air being introduced due to excessive flow rate, or the mixture cooling and solidifying in the channel due to excessive flow rate and failure to fill. Quantitative control through the formula can ensure that the secondary injection parameters of each batch are consistent and improve the stability of the fusion quality.

[0027] Furthermore, the vulcanization holding time in step S5 is calculated using the formula T1=h×kT; Where T1 is the vulcanization holding time, h is the maximum wall thickness of the product in mm, and kT is the time coefficient 20-30s / mm. When the calculated value is less than 20s, take 20s; when it is greater than 30s, take 30s. Cooling time is calculated using the formula T2=(T3-T4)×C; Where T2 is the cooling time, T3 is the vulcanization temperature (150-170℃), T4 is the demolding temperature (50-60℃), and C is the cooling coefficient (0.8-1.2s / ℃). The cooling time is calculated based on the temperature difference and the cooling coefficient and can be precisely adjusted according to the actual cooling capacity. This ensures that the product is fully cooled and easy to demold, while avoiding excessive cooling time that would reduce production efficiency, thus achieving a balance between performance and efficiency.

[0028] Example 2, as Figure 2 As shown, a two-color injection molding mold for silicone products is used to realize the two-color injection molding process of silicone products. It includes a fixed mold, a moving mold, and two independent cavities corresponding to silicone mixture A and silicone mixture B, respectively. The two cavities are connected by a guide channel.

[0029] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] Obviously, the embodiments described above are merely some embodiments of the present invention, not all embodiments. The accompanying drawings show preferred embodiments of the present invention, but do not limit the patent scope of the present invention. The present invention can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this invention.

Claims

1. A two-color injection molding process for a silicone gel article, characterized by, The method comprises the following steps: S1, raw material pretreatment: two different color or performance of silica gel raw material is selected respectively, each silica gel raw material is mixed with vulcanizing agent to obtain uniform silica gel mixture A and silica gel mixture B; S2, mold preparation: using injection mold, the injection mold comprises a fixed mold, a movable mold and two independent cavities corresponding to silica gel mixture A and silica gel mixture B respectively, two cavities are communicated through flow channel, and a partition temperature control system is arranged in the mold; S3, first injection: silica gel mixture A is added to the first cylinder of the double-color injection molding machine, silica gel mixture A is injected into cavity A through injection, and pressure is maintained; S4, second injection: the mold is kept closed, silica gel mixture B is added to the second cylinder of the double-color injection molding machine, silica gel mixture B is injected into cavity B through the flow channel, and silica gel mixture B is fused with the silica gel mixture A in the cavity A which is not completely vulcanized at the bonding interface, and pressure is maintained; S5, vulcanization and demolding: the temperature of the mold is raised to 150-170℃, and vulcanization is carried out after heat preservation, and the mold is cooled after vulcanization, and the double-color silica gel product is taken out.

2. The two-color injection molding process of silicone articles according to claim 1, characterized in that, The vulcanizing agent in step S1 is dibenzoyl peroxide or 2,5-dimethyl-2,5-di-tert-butyl peroxide, and the mixing process of silica gel raw material and vulcanizing agent is carried out in a vacuum environment.

3. The two-color injection molding process for silicone articles of claim 1, wherein, The partition temperature control system in step S2 comprises a heating pipe and a temperature sensor corresponding to cavity A and cavity B respectively.

4. The two-color injection molding process for silicone articles of claim 1, wherein, The injection speed of the injection system in steps S3 and S4 is 50-80mm / s, and the injection process adopts segmented injection mode, the first injection speed is 50-60mm / s, and the second injection speed is 70-80mm / s.

5. The two-color injection molding process for silicone articles of claim 1, wherein, The cooling mode of the mold in step S5 is water cooling, the flow rate of cooling water is 3-5L / min, and after vulcanization, the segmented cooling mode is adopted, the mold temperature is first cooled from 150-170℃ to 100-120℃, and then cooled to 50-60℃ after heat preservation for 5-10 seconds.

6. The two-color injection molding process for silicone articles of claim 1, wherein, The hardness difference of the silica gel mixture A and the silica gel mixture B is Shore A 10°-30°, and one of the silica gel mixtures is conductive silica gel, the amount of conductive filler is calculated according to the formula M1=M2×ω, wherein M1 is the mass of conductive filler, M2 is the total mass of conductive silica gel mixture, and ω is the mass fraction of conductive filler, ω is 5%-10%, the conductive filler is carbon black or silver powder.

7. The two-color injection molding process for silicone articles of claim 1, wherein, The first injection pressure in step S3 is determined by the formula P1=P2×KL; Wherein P1 is the first injection pressure, P2 is the basic injection pressure of silica gel mixture A, 60-80MPa, and KL is the pressure correction coefficient, 1.1-1.3; And the injection amount satisfies V1=V2×(1+δ); Wherein V1 is the first injection amount, V2 is the volume of cavity A, and δ is the shrinkage rate, 5%-10%.

8. The two-color injection molding process for silicone articles of claim 1, wherein, The second injection pressure in step S4 is determined by the formula P3=P4×KQ; Wherein P3 is the second injection pressure, P4 is the basic injection pressure of silica gel mixture B, 50-70MPa, and KQ is the pressure correction coefficient, 1.2-1.4; The flow velocity v of silica gel in the flow channel satisfies v=Q / S, wherein Q is the secondary injection flow rate, S is the cross-sectional area of the flow channel, and v is controlled at 0.1-0.3 m / s.

9. The two-color injection molding process for silicone articles of claim 1, wherein, The curing holding time in step S5 is calculated according to the formula T1=h×kT; wherein T1 is the curing holding time, h is the maximum wall thickness of the product in mm, kT is a time coefficient of 20-30 s / mm, and when the calculated value is less than 20 s, 20 s is taken, and when the calculated value is greater than 30 s, 30 s is taken; The cooling time is calculated according to the formula T2=(T3-T4)×C; wherein T2 is the cooling time, T3 is the curing temperature of 150-170 ℃, T4 is the demolding temperature of 50-60 ℃, and C is a cooling coefficient of 0.8-1.2 s / ℃.

10. A two-color injection molding mold for a silicone article for carrying out the two-color injection molding process of any one of claims 1 to 9, characterized in that The mold includes a fixed mold, a movable mold, and two independent cavities corresponding to silica gel mixture A and silica gel mixture B respectively, and the two cavities are communicated through a flow channel.

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