Semi-transparent polyurethane rubber, its preparation method and use

Abstract

The application discloses a kind of translucent polyurethane rubber and its preparation method and application, the preparation raw material of the translucent polyurethane rubber includes raw rubber 65~70%, filler 20~25%, vulcanizing agent 2~2.5% and auxiliary agent 4.8~6.7% by weight percentage;Wherein, the raw rubber is transparent binary copolymer;The auxiliary agent at least includes processing aid 0.2~0.5%, coupling agent 0.5~0.7%, antioxidant 0.3~0.5%, UV agent 0.3~0.5%, plasticizer 2.5~3% and crosslinking auxiliary agent 1~1.5% by percentage;When preparing, raw rubber is first plasticated to obtain plasticated rubber, and other raw materials are mixed in advance and then mixed with plasticated rubber, and then automatically tumble, cool, finally vulcanized to form polyurethane rubber, the preparation method is simple, easy to realize, and the prepared polyurethane rubber can meet the requirements of transparency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane rubber, in particular to a kind of translucent polyurethane rubber and its preparation method and application. BACKGROUND

[0002] Polyurethane raw materials are various, and mixing type polyurethane rubber MPU is increasingly widely used in products, because its transparency is better than fluorine rubber, hydrogenated nitrile rubber HNBR, fluorosilicone rubber and the like in various special rubbers, and it has advantages in strength, cost and transparency, so that polyurethane rubber is increasingly used in intelligent wearable electronic products and optical products.

[0003] At present, the existing polyurethane rubber has low production efficiency due to complex process flow in preparation process, and the prepared polyurethane rubber has particle inclusions, and the transparency effect is poor, thereby limiting the application range of polyurethane rubber. SUMMARY

[0004] Therefore, the present application aims to provide a kind of translucent polyurethane rubber and its preparation method and application, to solve the problems of complex preparation process, low production efficiency and poor transparency in the prior art.

[0005] To achieve the above-mentioned purpose, a technical scheme of the present application provides a kind of translucent polyurethane rubber, and the preparation raw materials of the translucent polyurethane rubber include raw rubber 65-70%, filler 20-25%, vulcanizing agent 2-2.5% and auxiliary agent 4.8-6.7% by weight percentage;Among them, the raw rubber is transparent copolymer.

[0006] Further, the filler at least includes gas phase white carbon black with particle size of 200-300 mesh.

[0007] Further, the vulcanizing agent at least includes 2,5-dimethyl-2,5-bis(tert-butyl peroxy) hexane.

[0008] Further, the auxiliary agent at least includes processing aid 0.2-0.5%, coupling agent 0.5-0.7%, antioxidant 0.3-0.5%, UV agent 0.3-0.5%, plasticizer 2.5-3% and crosslinking aid 1-1.5% by percentage.

[0009] Further, the processing aid at least includes octadecanoic acid; the coupling agent at least includes vinyl tri(b-methoxyethoxy)silane; the antioxidant at least includes diethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]; the UV agent at least includes 2-(2'-hydroxy-5'-methylphenyl)benzotriazole; the plasticizer at least includes cyclohexane 1,2-dicarboxylic acid diisononyl ester; and the crosslinking aid at least includes trimethylolpropane trimethacrylate.

[0010] To solve the above technical problems, another technical scheme of the present application provides a preparation method of a translucent polyurethane rubber, comprising the following steps:

[0011] Weighing: respectively weighing raw rubber 65-70%, filler 20-25%, vulcanizing agent 2-2.5%, and auxiliary agent 4.8-6.7% according to percentage;

[0012] Plasticizing and internal mixing: plasticizing the raw rubber to obtain plasticized rubber, and adding the filler, vulcanizing agent and auxiliary agent into the plasticized rubber to obtain internal mixed rubber;

[0013] Turnover and cooling: turnover of the internal mixed rubber, and cooling after turnover to obtain preformed rubber;

[0014] Vulcanization forming: vulcanization forming of the preformed rubber, to obtain the translucent polyurethane rubber.

[0015] Further, in the step of plasticizing and internal mixing, the plasticizing time is 3-5 min, and the plasticizing temperature is not more than 100℃; the internal mixing time is 10-15 min, and the internal mixing temperature is not more than 100℃.

[0016] Further, in the step of turnover and cooling, the turnover time is 10-15 min, and the turnover temperature is not more than 70℃; and the cooling temperature is not more than 40℃.

[0017] Further, in the step of vulcanization forming, the pressure of vulcanization forming is 180-200 kg, the vulcanization time is 200-250 s, and the vulcanization temperature is 172±5℃.

[0018] To solve the above technical problems, still another technical scheme of the present application provides a translucent polyurethane rubber for manufacturing a watchband of a watch, which is the translucent polyurethane rubber as described above or is prepared by the preparation method of the translucent polyurethane rubber as described above.

[0019] The present application can weaken the covering of the powder filler to the prepared polyurethane rubber, and further ensure that the prepared rubber has good color transmission effect; and in the preparation process, the liquid additives and vulcanizing agents are first mixed with the filler with fine particle size and good oil absorption value, and then mixed and kneaded with the plasticated raw rubber, which is beneficial to avoid the dynamic loss of the liquid additives and vulcanizing agents in the mixing process, so as to further increase the performance of the prepared polyurethane rubber, and the composition is simple, which can not only simplify the process flow, but also avoid the influence of too many components on the color transmission effect of the prepared polyurethane rubber. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The flow chart of the preparation method of the semi-transparent polyurethane rubber of an embodiment of the present application. DETAILED DESCRIPTION

[0021] The following will be further described in detail through specific embodiments:

[0022] Example 1

[0023] An embodiment of the present application provides a semi-transparent polyurethane rubber, and the preparation raw materials of the semi-transparent polyurethane rubber include raw rubber 65-70%, filler 20-25%, vulcanizing agent 2-2.5%, and additive 4.8-6.7% by weight percentage. In the embodiment, the raw rubber adopts transparent polyether type mixed polyurethane rubber, which mainly includes a binary copolymer of polyether polyol and diphenyl methane diisocyanate; the polyether type mixed polyurethane rubber is selected, which has good plasticity on the basis of meeting the processing process requirements, and after plasticizing for a certain time, the elasticity decreases, the plasticity can be further improved, and the fluidity is improved, so that the solubility and adhesion of the subsequent rubber can be improved.

[0024] The filler selects fumed white carbon black with fine particle size, and the material composition is mainly silicon dioxide (i.e. fumed silicon dioxide); since the fumed white carbon black is a powder filler, it can cover the polyurethane rubber to a certain extent, so that it presents a semi-transparent state, and in order to avoid too much covering of the filler to the polyurethane rubber, the fumed white carbon black with particle size of 200-300 mesh is preferably adopted, since the particle size is small, it is beneficial to dispersion when mixing with the additive and the vulcanizing agent, and then mixed with the plasticated raw rubber for kneading, which can not only reduce the preparation difficulty of the semi-transparent polyurethane rubber, but also avoid the dynamic loss of the liquid additive and the vulcanizing agent in the mixing process.

[0025] In the embodiment, the vulcanizing agent is selected from 2,5-dimethyl-2,5-bis(tert-butyl peroxy) hexane. In other embodiments, other vulcanizing agents can be used. The auxiliary agent includes 0.2-0.5% processing agent, 0.5-0.7% coupling agent, 0.3-0.5% antioxidant, 0.3-0.5% UV agent, 2.5-3% plasticizer, and 1-1.5% crosslinking agent. In the embodiment, the processing agent is selected from C 18 H 36 O2 octadecanoic acid to improve the flowability of the raw rubber, so that the rubber compound can be quickly spread during the molding process, thereby accelerating the plasticizing process of the rubber compound; the coupling agent is selected from silane coupling agent A-172 with ethenyl tri(b-methoxy ethoxy) silane as the main component to improve the viscosity of the raw rubber; the antioxidant is selected from

[0026] 0 triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methyl phenyl) propionate] to inhibit the thermal or light effects of the components during the processing; the UV agent is selected from

[0027] ultraviolet absorber UV-P with 2-(2ˊ-hydroxy-5ˊ-methyl phenyl) benzotriazole as the main component to improve the adhesion of the subsequent rubber molding; the plasticizer is selected from plasticizer (i.e., C 26 H 48 O4) with cyclohexane 1,2-dicarboxylic acid diisononyl ester as the main component to improve the flexibility and surface hardness of the rubber compound;

[0028] The crosslinking agent is selected from thermal crosslinking agent with trimethylolpropane trimethacrylate as the main component to improve the elasticity of the rubber compound and accelerate the vulcanization.

[0029] In other embodiments, other processing agents, coupling agents, antioxidants, UV agents, plasticizers, and crosslinking agents can be used.

[0030] The translucent polyurethane rubber of the embodiment uses raw rubber with high transparency as the main material, fine powder as the filler, and liquid auxiliary agent and vulcanizing agent in the preparation process, which can weaken the covering of the powder filler on the prepared polyurethane rubber and further ensure that the prepared rubber has good color transmission effect, wide application range, simple process, and low cost.

[0031]

[0032] Embodiment 2 ​

[0033] As Figure 1 shown, a flow chart of a preparation method 5 of a translucent polyurethane rubber is provided for an embodiment of the present application, which is used for preparing the translucent polyurethane rubber in embodiment 1. Specifically, the present embodiment comprises the following steps:

[0034] S1: weighing.

[0035] Specifically, the raw rubber 65-70%, the filler 20-25%, the vulcanizing agent 2-2.5%, and the auxiliary agent 4.8-6.7% are weighed according to the percentage, respectively. In the present embodiment, the components of the auxiliary agent at least include the processing agent 0.2-0.5%, the coupling agent 0.5-0.7%, the antioxidant 0.3-0.5%, the UV agent 0.3-0.5%, the plasticizer 2.5-3%, and the crosslinking auxiliary agent 1-1.5% according to the percentage. In the specific implementation of the present embodiment, the weighing of the raw materials can also be carried out according to other metering methods, such as weighing or by parts, as long as the proportion of the weighed raw materials meets the above requirements.

[0036] In the present embodiment, the raw rubber adopts the transparent polyether type mixed polyurethane rubber, which mainly includes the copolymer of polyether polyol and diphenyl methane diisocyanate. The selection of the polyether type mixed polyurethane rubber can improve the plasticity, the solubility of the subsequent rubber compound, and the adhesion of the molding, and can further improve the plasticity and the flowability after a certain time of plasticizing, thereby reducing the elasticity.

[0037] The filler selects the fumed white carbon black with a relatively fine particle size, and the material component is mainly silicon dioxide (i.e. fumed silicon dioxide). Since the fumed white carbon black is a powder filler, it can cover the polyurethane rubber to a certain extent, so that the polyurethane rubber presents a translucent state. In order to avoid that the filler covers too much polyurethane rubber, the fumed white carbon black with a particle size of 200-300 mesh is preferably used. Since the particle size is small, it is easy to disperse when mixing with the auxiliary agent and the vulcanizing agent, and then mix with the plasticized raw rubber after mixing with the auxiliary agent and the vulcanizing agent, so as to reduce the preparation difficulty of the translucent polyurethane rubber, and avoid the dynamic loss of the liquid auxiliary agent and the vulcanizing agent in the mixing process.

[0038] In the embodiment, the vulcanizing agent is mainly composed of 2,5-dimethyl-2,5-bis(tert-butyl peroxy) hexane. It can be understood that in some other embodiments, the vulcanizing agent can also be selected from other components of the vulcanizing agent. The components of the auxiliary agent include at least 0.2-0.5% of processing aid, 0.5-0.7% of coupling agent, 0.3-0.5% of antioxidant, 0.3-0.5% of UV agent, 2.5-3% of plasticizer, and 1-1.5% of crosslinking aid. In the embodiment, the processing aid is mainly composed of C 18 H 36 O2 is octadecanoic acid, which is used to improve the flowability of the raw rubber, so that the rubber is easily spread during the molding process, thereby accelerating the plasticizing process of the rubber in the internal mixer; the coupling agent is mainly composed of vinyl tri(b-methoxyethoxy) silane silane coupling agent A-172, which is used to improve the viscosity of the raw rubber; the antioxidant is mainly composed of di-triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate], which is used to inhibit the heat or light effect of each component during the processing; the UV agent is mainly composed of 2-(2'-hydroxy-5'-methylphenyl) benzotriazole ultraviolet absorber UV-P, which is used to improve the adhesion of the subsequent rubber molding; the plasticizer is mainly composed of cyclohexane 1,2-dicarboxylic acid diisononyl ester plasticizer (i.e. C 26 H 48 O4), which is used to improve the flexibility and surface hardness of the rubber; the crosslinking aid is mainly composed of trimethylolpropane trimethyl acrylate thermal crosslinking agent, which is used to improve the elasticity of the rubber and accelerate the vulcanization.

[0039] It can be understood that in some other embodiments, the processing aid, coupling agent, antioxidant, UV agent, plasticizer, and crosslinking aid can also be selected from other components of the processing aid, coupling agent, antioxidant, UV agent, plasticizer, and crosslinking aid.

[0040] S2: plasticizing and internal mixing.

[0041] First, the weighed raw rubber is plasticized to obtain plasticized rubber, which reduces the elasticity of the raw rubber, improves the plasticity of the plasticized rubber, reduces the viscosity of the raw rubber, improves the flowability, and further improves the solubility and molding adhesion of the rubber. In order to ensure the strength, elasticity and wear resistance of the plasticized rubber, and to reduce the power consumption of the plasticizing equipment, the plasticizing period should not be too long. In the embodiment, the plasticizing time of the raw rubber is 3-5 min, and the plasticizing temperature is not more than 100°C.

[0042] Then, the weighed fillers, vulcanizing agent and auxiliary agent are pre-mixed to make the powder-like fillers fully dissolved in the liquid vulcanizing agent and auxiliary agent, which can reduce the difficulty in preparing the translucent polyurethane rubber and avoid the dynamic loss of the liquid auxiliary agent and vulcanizing agent in the mixing process.

[0043] Finally, the mixed fillers, vulcanizing agent and auxiliary agent are added into the plasticated rubber to perform the mixing to obtain the mixed rubber; during the mixing, the fillers, vulcanizing agent and auxiliary agent can be added into the plasticated rubber at one time to reduce the power consumption of the mixing equipment caused by the batch addition. In the embodiment, the mixing time of the raw materials is 10-15 min, and the mixing temperature is not higher than 100℃.

[0044] S3: plasticating and cooling.

[0045] Specifically, the mixed rubber is automatically plasticated to continuously mix the raw materials. In the embodiment, the plasticating time of the mixed rubber is 10-15 min, and the plasticating temperature is not higher than 70℃. After the automatic plastication of the mixed rubber is completed, the mixed rubber is cooled until the cooling temperature is not higher than 40℃, to obtain the pre-formed rubber.

[0046] S4: vulcanization forming.

[0047] Specifically, the cooled pre-formed rubber is placed in a mold to perform the vulcanization forming, to obtain the translucent polyurethane rubber. In the embodiment, the vulcanization forming pressure is 180-200 kg, the vulcanization time is 200-250 s, and the vulcanization temperature is 172±5℃.

[0048] During the vulcanization forming, the hardness of the translucent polyurethane rubber is 65-72A, which is tested by using a Shore hardness tester under the vulcanization temperature of 177±3℃ for 250 s; the tensile strength of the translucent polyurethane rubber is 20-22 MPa, and the elongation rate is 300-450%, which are tested after the preheating at 121℃ for 1 min, the testing for 4 min, and the cooling for 4 hours after the secondary vulcanization at 175℃ for 2 hours under the vulcanization forming pressure of 180 kg and the vulcanization temperature of 177±3℃ for 250 s; the Mooney viscosity of the translucent polyurethane rubber is 80-90 MU, which is tested by using a Mooney viscometer under the preheating at 121℃ for 1 min and the testing for 4 min; finally, the T10 (i.e. scorch time) is 20-35 s, and the T90 (i.e. process vulcanization time) is 80-120 s, which are tested by using a rotorless vulcanization instrument, so it can be known that the translucent polyurethane rubber prepared by using the method has good fluidity, better mechanical properties, shorter vulcanization time, easy forming, and good stability.

[0049] The watchband made of the translucent polyurethane rubber prepared by the preparation method of the translucent polyurethane rubber has better color transmission effect, uniform texture and smoothness.

[0050] Example 3

[0051] This embodiment is a specific implementation example of the preparation method of the translucent polyurethane rubber of the embodiment of the present application. The embodiment specifically comprises the following steps:

[0052] S301: weighing.

[0053] Specifically, the raw rubber 70%, fumed white carbon black 22%, vulcanizing agent 2.3%, processing aid 0.5%, coupling agent 0.7%, antioxidant 0.5%, UV agent 0.5%, plasticizer 2% and crosslinking aid 1.5% are weighed according to the percentage respectively. In this embodiment, the raw rubber is polyether type mixed polyurethane rubber; the particle size of the fumed white carbon black is selected as 300 mesh fumed silica; the vulcanizing agent is selected as double 25; the processing aid is selected as octadecanoic acid; the coupling agent is selected as silane coupling agent A-172; the antioxidant is selected as triethylene glycol bis; the UV agent is selected as ultraviolet absorber UV-P; the plasticizer is selected as C 26 H 48 O4; and the crosslinking aid is selected as thermal crosslinking agent.

[0054] S302: plasticizing and internal mixing.

[0055] Firstly, 70% of the raw rubber is placed in a plasticizing chamber at 100°C for plasticizing for 5 min to obtain plasticized rubber material; then, 22% of the fumed white carbon black, 2.3% of the vulcanizing agent, 0.5% of the processing aid, 0.7% of the coupling agent, 0.5% of the antioxidant, 0.5% of the UV agent, 2% of the plasticizer and 1.5% of the crosslinking aid are pre-mixed to make the powder-like fumed white carbon black fully dissolved in the liquid vulcanizing agent and various aids; finally, the mixed fumed white carbon black, vulcanizing agent and aids are added into the plasticized rubber material after plasticizing at one time and placed in an internal mixing chamber at 100°C for internal mixing for 15 min to obtain internal mixed rubber material.

[0056] S303: turning and cooling.

[0057] The internal mixed rubber material is placed in a turning device at 70°C for automatic turning for 15 min to make the internal mixed rubber material continue to be fully mixed; after the automatic turning of the internal mixed rubber material is completed, the internal mixed rubber material is cooled to below 40°C to obtain preformed rubber material.

[0058] S304: vulcanization forming.

[0059] The preformed rubber after cooling is placed in a mold for vulcanization molding, the pressure for vulcanization molding is set as 180 kg, the vulcanization time is 250 s, and the vulcanization temperature is 177 ℃, and a translucent polyurethane rubber is obtained.

[0060] In the vulcanization molding process, the hardness of the translucent polyurethane rubber is 70A by hardness testing with a Shore hardness tester; the tensile strength of the translucent polyurethane rubber is 22 MPa and the elongation is 450% by tensile strength and elongation testing after secondary vulcanization at 175 ℃ for 2 hours and cooling for 4 hours; the Mooney viscosity of the translucent polyurethane rubber is 90 MU by Mooney viscosity testing with a Mooney viscometer; finally, the T10 (i.e. scorch time) is 35 s and the T90 (i.e. process curing time) is 80 s by vulcanization curve testing with a rotorless vulcanizer, so it can be known that the translucent polyurethane rubber prepared by the application has good fluidity and better mechanical properties, shorter vulcanization time, easy molding and good stability.

[0061] Example 4

[0062] This embodiment is a specific example of the preparation method of the translucent polyurethane rubber of the embodiment of the application. The embodiment specifically includes the following steps:

[0063] S401: weighing.

[0064] Specifically, the raw rubber 68%, fumed white carbon black 24.3%, vulcanizing agent 2.5%, processing aid 0.5%, coupling agent 0.5%, antioxidant 0.5%, UV agent 0.5%, plasticizer 2% and crosslinking aid 1.2% are weighed according to the percentage respectively. In this embodiment, the raw rubber is polyether type mixed polyurethane rubber; the particle size of the fumed white carbon black is selected as 240 mesh fumed silica; the vulcanizing agent is selected as bis-dipent; the processing aid is selected as octadecanoic acid; the coupling agent is selected as silane coupling agent A-172; the antioxidant is selected as triethylene glycol bis; the UV agent is selected as ultraviolet absorber UV-P; the plasticizer is selected as C 26 H 48 O4; and the crosslinking aid is selected as thermal crosslinking agent.

[0065] S402: plasticizing and dense mixing.

[0066] Firstly, 68% of raw rubber is plasticized in a plasticizing chamber at 95℃ for 4 minutes to obtain plasticized rubber; then 24.3% of fumed white carbon black, 2.5% of vulcanizing agent, 0.5% of processing aid, 0.5% of coupling agent, 0.5% of antioxidant, 0.5% of UV agent, 2% of plasticizer and 1.2% of crosslinking aid are pre-mixed to make the powder-like fumed white carbon black fully dissolved in the liquid vulcanizing agent and each aid; finally, the mixed fumed white carbon black, vulcanizing agent and aid are added into the plasticized plasticized rubber at one time and placed in a 95℃ mixing chamber for mixing for 12 minutes to obtain a mixed rubber.

[0067] S403: re-mixing and cooling.

[0068] The mixed rubber is placed in a re-mixing device at 68℃ for automatic re-mixing for 13 minutes to make the mixed rubber continue to be fully mixed; after the automatic re-mixing of the mixed rubber is completed, the mixed rubber is cooled to below 35℃ to obtain a pre-formed rubber.

[0069] S404: vulcanization forming.

[0070] The cooled pre-formed rubber is placed in a mold for vulcanization forming, the pressure of vulcanization forming is set to 188kg, the vulcanization time is 200s and the vulcanization temperature is 175℃, to obtain a translucent polyurethane rubber.

[0071] During the vulcanization forming, a hardness tester is used for hardness testing, the hardness of the translucent polyurethane rubber is 68A; after secondary vulcanization at 175℃ for 2 hours and cooling for 4 hours, tensile strength and elongation rate testing is performed, the tensile strength of the translucent polyurethane rubber is 20MPA and the elongation rate is 382%; a Mooney viscosity tester is used for Mooney viscosity testing, the Mooney viscosity of the translucent polyurethane rubber is 87MU, finally a rotorless vulcanization tester is used for vulcanization curve testing, T10 (i.e. scorch time) is 32s and T90 (i.e. process curing time) is 98s, so it can be seen that the translucent polyurethane rubber prepared by the application has good fluidity and good mechanical properties, short vulcanization time, easy molding and good stability.

Claims

1. A translucent polyurethane rubber, characterized in that, The raw materials for preparing the translucent polyurethane rubber, by weight percentage, include 65-70% raw rubber, 20-25% filler, 2-2.5% liquid vulcanizing agent, and 4.8-6.7% liquid additives; wherein the raw rubber is a transparent binary copolymer, the filler includes at least powdered fumed silica, and the liquid additives, by weight percentage, include at least 0.2-0.5% processing aid, 0.5-0.7% coupling agent, 0.3-0.5% antioxidant, 0.3-0.5% UV agent, 2.5-3% plasticizer, and 1-1.5% crosslinking aid; the fumed silica is premixed with the liquid additives and liquid vulcanizing agent to ensure that the powdered fumed silica is fully dissolved in the liquid vulcanizing agent and additives; the particle size of the fumed silica is 200-300 mesh.

2. The translucent polyurethane rubber according to claim 1, characterized in that, The vulcanizing agent includes at least 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

3. The translucent polyurethane rubber according to claim 1, characterized in that, The processing aid includes at least octadecanoic acid; the coupling agent includes at least vinyltris(b-methoxyethoxy)silane; the antioxidant includes at least triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]; the UV agent includes at least 2-(2ˊ-hydroxy-5ˊ-methylphenyl)benzotriazole; the plasticizer includes at least diisononyl cyclohexane-1,2-dicarboxylate; and the crosslinking aid includes at least trimethylolpropane trimethacrylate.

4. A method for preparing translucent polyurethane rubber as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Weighing: Weigh out 65-70% raw rubber, 20-25% filler, 2-2.5% liquid vulcanizing agent and 4.8-6.7% liquid additives according to the percentages, wherein the filler includes at least powdered fumed silica; Plasticizing and internal mixing: The raw rubber is plasticized to obtain plasticized rubber compound; then, the weighed filler, liquid vulcanizing agent and liquid additives are pre-mixed to fully dissolve the powdered filler in the liquid vulcanizing agent and liquid additives, and the mixed filler, liquid vulcanizing agent and liquid additives are added to the plasticized rubber compound for internal mixing to obtain internally mixed rubber compound; Refining and Cooling: The internally mixed rubber compound is refined and then cooled to obtain a pre-formed rubber compound; Vulcanization molding: The pre-formed rubber compound is vulcanized to obtain a semi-transparent polyurethane rubber.

5. The method for preparing translucent polyurethane rubber according to claim 4, characterized in that, In the plasticizing and internal mixing steps, the plasticizing time is 3-5 minutes and the plasticizing temperature does not exceed 100°C; the internal mixing time is 10-15 minutes and the internal mixing temperature does not exceed 100°C.

6. The method for preparing translucent polyurethane rubber according to claim 4, characterized in that, In the steps of turning and cooling, the turning time is 10-15 minutes, the turning temperature does not exceed 70°C, and the cooling temperature does not exceed 40°C.

7. The method for preparing translucent polyurethane rubber according to claim 6, characterized in that, In the vulcanization molding step, the vulcanization molding pressure is 180~200kg, the vulcanization time is 200~250s, and the vulcanization temperature is 172±5℃.

8. A translucent polyurethane rubber for making watch straps, characterized in that, The translucent polyurethane rubber is the translucent polyurethane rubber as described in any one of claims 1 to 3 or is prepared by the preparation method of the translucent polyurethane rubber as described in any one of claims 4 to 7.

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