A silicone rubber thermoplastic elastomer with good compatibility of each component and a preparation method thereof

Abstract

A silicone rubber thermoplastic elastomer with good compatibility of each component and a preparation method thereof, belonging to the field of organic polymers, wherein the elastomer composition is by weight: polyurethane 118-123, silicone rubber 79-81, white carbon black 19-21, compatibilizer 2-3, vulcanizer DBPH 2-3. Wherein, the compatibilizer is monostearate sorbitan ester, and its preparation process is prepared by reacting edible industrial stearic acid with sorbic anhydride. Its preparation method includes the following steps, mixing polyurethane and silicone rubber, white carbon black, compatibilizer, blending for a period of time, then adding a corresponding proportion of vulcanizer, performing dynamic vulcanization, and extruding using a twin-screw extruder. The present invention optimizes the design of the components, combines the improvement of the process, and obtains a silicone rubber thermoplastic elastomer with good compatibility of each component, and the maximum tensile strength is increased by more than 50%.

Description

Technical Field

[0001] The present application relates to a silicone rubber thermoplastic elastomer with good compatibility among its components and a preparation method thereof, and belongs to the field of organic polymers. Background Art

[0002] Thermoplastic Elastomer Thermoplastic elastomer (TPE) is a new type of polymer synthetic material. It is an elastomer made of polymers or polymer blends that has properties similar to vulcanized rubber at room temperature and the same properties as thermoplastic resins when the temperature rises. It can be molded or remolded. The characteristics of TPE that have both rubber and plastic properties are derived from its unique segment structure, that is, the rubber segment (soft segment) and resin segment (hard segment) composed of chemical bonds exist at the same time. Hard segments and soft segments of appropriate lengths are connected in an appropriate order and manner. The former is a highly elastic segment that contributes elasticity; the latter interacts and condenses into micro-regions (such as antagonistic micro-regions, ionic micro-regions, etc.), playing the role of intermolecular chemical or physical cross-linking points. This cross-linking changes reversibly with temperature. When the temperature rises to a certain temperature, this cross-linking disappears; when cooled to room temperature, this cross-linking plays a role similar to the cross-linking bond of vulcanized rubber; when the temperature rises to a temperature exceeding the glass transition temperature or crystalline melting point of the hard segment, the hard segment softens or melts, the cross-linking network structure is destroyed, and the polymer becomes plastic. Compared with traditional vulcanized rubber, on the one hand, the production process of thermoplastic elastomers does not require vulcanization, and its industrial production process is greatly shortened, which achieves the purpose of energy saving to a large extent; on the other hand, TPE has plastic processing characteristics during processing, which fundamentally solves the problem that traditional thermosetting rubber is difficult to recycle and reuse, and has great potential economic and social benefits.

[0003] According to the difference in preparation methods, thermoplastic elastomers are mainly divided into two categories: chemically synthesized thermoplastic elastomers and rubber-plastic blended thermoplastic elastomers. The chemically synthesized type appears alone in the form of a polymer, and there are main chain copolymerization, branch copolymerization and ionic polymerization. The rubber-plastic blend is mainly a blend of rubber and resin.

[0004] There are many kinds of thermoplastic elastomers that have been industrially produced in the world, but some of them have the defect of high permanent compression deformation. For example, the permanent compression deformation of ordinary soft PVC is more than 65%, and the permanent compression deformation rate of improved TPVC is also more than 25%. Silicone rubber / polyurethane dynamically vulcanized thermoplastic elastomer (TPV) has good mechanical properties, good fluidity and excellent elasticity at high temperatures, and is easy to extrude, has a low surface friction coefficient, is non-toxic and harmless, and has a good touch. Therefore, it has good application prospects. However, since silicone rubber and polyurethane are thermodynamically incompatible systems, their blends are prone to phase separation, which will lead to poor performance. In the prior art, compatibilizers are usually added to increase the capacity.

[0005] CN102690479A discloses a polyamide / ethylene vinyl acetate rubber thermoplastic elastomer and a preparation method thereof, wherein ethylene vinyl acetate rubber, polyamide, a compatibilizer and a crosslinking agent are formed, and in an internal mixer, an open mixer or a screw extruder, at a certain mixing temperature, a compatibilizer is added to a polyamide / ethylene vinyl acetate rubber blend to improve the blending compatibility of polyamide and ethylene vinyl acetate rubber, and while shearing, a peroxide crosslinking agent vulcanizes the ethylene vinyl acetate rubber, and the blend undergoes a phase inversion, from polyamide dispersed in a rubber continuous phase to a crosslinked micron-sized rubber particle dispersed in a polyamide continuous phase, to obtain a high-rubber content and high-performance polyamide / ethylene vinyl acetate rubber blended thermoplastic elastomer. This method does not achieve a good permanent deformation rate, and its compatibilizer effect is not up to standard.

[0006] CN117247669A discloses a nano-silicon dioxide-compatible silicone rubber / thermoplastic polyurethane blended elastomer and a preparation method thereof. Nano-silicon dioxide modified in situ by a silane coupling agent containing double bonds is used as a reinforcing and compatibilizing material. The double bonds on the surface of silicon dioxide increase the cross-linking density of the composite material, increase the compatibility of the two, and thus improve its mechanical properties. The cost is relatively high, and the nanoparticles will affect the strength of the material.

[0007] In summary, existing compatibilizers have disadvantages such as high cost, environmental pollution, toxicity or high permanent compression deformation ratio of the final product. Therefore, how to obtain a silicone rubber thermoplastic elastomer with low cost, environmental protection and good performance and good compatibility of each component is a problem that needs to be solved. Summary of the invention

[0008] The invention optimizes the design of components and improves the process to obtain a silicone rubber thermoplastic elastomer with good compatibility of components and an increase of more than 50% in maximum tensile strength.

[0009] Specifically: The present invention provides a silicone rubber thermoplastic elastomer with good compatibility of each component, and its composition is as follows in weight parts:

[0010] Polyurethane 118-123, silicone rubber 79-81, white carbon black 19-21, compatibilizer 2-3, vulcanizing agent DBPH 2-3.

[0011] The extender is sorbitan monostearate, and its preparation process is to react edible industrial stearic acid with sorbic anhydride.

[0012] The preparation method of the silicone rubber thermoplastic elastomer comprises the following steps: mixing polyurethane and silicone rubber, white carbon black and a compatibilizer, blending for a period of time, adding a corresponding proportion of a vulcanizing agent, performing dynamic vulcanization, and extruding using a twin-screw extruder.

[0013] The blending temperature is 180-220° C., and the blending time is 9-12 minutes.

[0014] The dynamic vulcanization temperature is 135-150°C, and the vulcanization time is 3-60 minutes.

[0015] The extrusion temperature of the twin-screw extruder is 170-180°C.

[0016] The present invention innovatively discovers that sorbitan monostearate can activate the interface between silicone rubber and polyurethane, reduce interfacial tension, and enhance interfacial bonding strength, thereby reducing the interfacial tension between silicone rubber and polyurethane that are originally microscopically immiscible, improving the degree of phase dispersion and the uniformity of dispersion, thereby forming a stable morphological structure.

[0017] The maximum tensile strength of the silicone rubber thermoplastic elastomer obtained by the invention is increased by more than 50%, and the permanent compression deformation rate is reduced to between 20-30%. DETAILED DESCRIPTION

[0018] Example 1

[0019] A silicone rubber thermoplastic elastomer with good compatibility of components, the composition of which is as follows by weight:

[0020] Polyurethane 120, silicone rubber 80, white carbon black 20, sorbitan monostearate 3, vulcanizing agent DBPH 3.

[0021] The preparation process of sorbitan monostearate is to prepare the product by reacting edible industrial stearic acid with sorbic anhydride, and the bulking agent is sorbitan monostearate.

[0022] The preparation method of the silicone rubber thermoplastic elastomer comprises the following steps: mixing polyurethane and silicone rubber, white carbon black and a compatibilizer at 200° C., blending for 10 minutes, then adding a corresponding proportion of a vulcanizing agent, performing dynamic vulcanization at 140° C. for 10 minutes, and extruding at 180° C. using a twin-screw extruder.

[0023] The measurement showed that the tensile strength of the prepared silicone rubber thermoplastic elastomer was 12.6 MPa and the permanent compression deformation rate was 26%.

[0024] Example 2

[0025] A silicone rubber thermoplastic elastomer with good compatibility of components, the composition of which is as follows by weight:

[0026] Polyurethane 120, silicone rubber 80, white carbon black 20, sorbitan monostearate 2, vulcanizing agent DBPH 3.

[0027] The preparation process of sorbitan monostearate is to prepare the product by reacting edible industrial stearic acid with sorbic anhydride, and the bulking agent is sorbitan monostearate.

[0028] The preparation method of the silicone rubber thermoplastic elastomer comprises the following steps: mixing polyurethane and silicone rubber, white carbon black and a compatibilizer at 200° C., blending for 10 minutes, then adding a corresponding proportion of a vulcanizing agent, performing dynamic vulcanization at 140° C. for 10 minutes, and extruding at 180° C. using a twin-screw extruder.

[0029] According to the measurement, the tensile strength of the prepared silicone rubber thermoplastic elastomer is 13MPa and the permanent compression deformation rate is 24%.

[0030] Example 3

[0031] A silicone rubber thermoplastic elastomer with good compatibility of components, the composition of which is as follows by weight:

[0032] Polyurethane 120, silicone rubber 80, white carbon black 20, sorbitan monostearate 2.5, vulcanizing agent DBPH 3.

[0033] The preparation process of sorbitan monostearate is to prepare the product by reacting edible industrial stearic acid with sorbic anhydride, and the bulking agent is sorbitan monostearate.

[0034] The preparation method of the silicone rubber thermoplastic elastomer comprises the following steps: mixing polyurethane and silicone rubber, white carbon black and a compatibilizer at 200° C., blending for 10 minutes, then adding a corresponding proportion of a vulcanizing agent, performing dynamic vulcanization at 140° C. for 10 minutes, and extruding at 180° C. using a twin-screw extruder.

[0035] According to the measurement, the tensile strength of the prepared silicone rubber thermoplastic elastomer is 14MPa and the permanent compression deformation rate is 22%.

[0036] Comparative Example 1

[0037] A silicone rubber thermoplastic elastomer, the composition of which is as follows by weight:

[0038] Polyurethane 120, silicone rubber 80, white carbon black 20, vulcanizing agent DBPH 3.

[0039] The preparation method of the silicone rubber thermoplastic elastomer comprises the following steps: mixing polyurethane, silicone rubber and white carbon black at 200° C. for 10 minutes, then adding a corresponding proportion of a vulcanizing agent, performing dynamic vulcanization at 140° C. for 10 minutes, and extruding at 180° C. using a twin-screw extruder.

[0040] According to the measurement, the tensile strength of the prepared silicone rubber thermoplastic elastomer is 8MPa and the permanent compression deformation rate is 46%.

[0041] Comparative Example 2

[0042] A silicone rubber thermoplastic elastomer with good compatibility of components, the composition of which is as follows by weight:

[0043] Polyurethane 120, silicone rubber 80, white carbon black 20, sorbitan monostearate 4, vulcanizing agent DBPH 3.

[0044] The preparation process of sorbitan monostearate is to prepare the product by reacting edible industrial stearic acid with sorbic anhydride, and the bulking agent is sorbitan monostearate.

[0045] The preparation method of the silicone rubber thermoplastic elastomer comprises the following steps: mixing polyurethane and silicone rubber, white carbon black and a compatibilizer at 200° C., blending for 10 minutes, then adding a corresponding proportion of a vulcanizing agent, performing dynamic vulcanization at 140° C. for 10 minutes, and extruding at 180° C. using a twin-screw extruder.

[0046] According to the measurement, the tensile strength of the prepared silicone rubber thermoplastic elastomer is 11 MPa and the permanent compression deformation rate is 31%.

[0047] The maximum tensile strength is measured in accordance with GB / T1040-1992.

[0048] Permanent compression set is tested according to GB / T 1683-1981 standard.

[0049] It can be seen from the above examples that the present invention adds a specific amount of compatibilizer to obtain a better technical effect. Without the compatibilizer, the strength and compression resistance are obviously insufficient, and if more compatibilizer is added, adverse reactions such as agglomeration will occur, which will affect the performance. Therefore, the silicone rubber thermoplastic elastomer with good compatibility of each component prepared by the present invention is non-toxic and harmless, has good performance, and is low in cost, and is suitable for products such as laptop computers, headphones, and various mobile phone shells or automobile interiors.

[0050] The embodiments disclosed above in the specification of the present invention are all exemplary, and the scope of protection shall be based on the claims. On the basis of the above exemplary embodiments, technical solutions formed by equivalent replacement or equivalent transformation shall all fall within the scope of protection required by the present invention.

Claims

1. A method for preparing a silicone rubber thermoplastic elastomer with good compatibility of components, wherein the composition is as follows in parts by weight: Polyurethane 118-123, silicone rubber 79-81, white carbon black 19-21, compatibilizer 2-3, vulcanizing agent DBPH 2-3, among which, The compatibilizer is sorbitan monostearate, and its preparation process is prepared by reacting edible industrial stearic acid with sorbic anhydride. The preparation method comprises the following steps: mixing polyurethane and silicone rubber, white carbon black, and the compatibilizer, blending for a period of time, then adding a corresponding proportion of a vulcanizer, performing dynamic vulcanization, and extruding using a twin-screw extruder.

2. The preparation method according to claim 1, wherein The blending temperature is 180-220°C and the blending time is 9-12 minutes.

3. The preparation method according to claim 1, wherein Dynamic vulcanization temperature is 135-150℃, and vulcanization time is 3-60 minutes.

4. The preparation method according to claim 1, wherein The extrusion temperature of the twin-screw extruder is 170-180°C.