Silicone rubber product as well as preparation method and application thereof

Abstract

The invention provides a silicone rubber product as well as a preparation method and application thereof, and belongs to the technical field of high polymer material processing. The method for preparing the silicone rubber product based on dynamic vulcanization comprises the following steps: mixing raw silicone rubber, an amphiphilic block copolymer, a dynamic cross-linking agent and a nano filler to obtain a premixed rubber material; carrying out dynamic vulcanization on the premixed rubber material at the temperature of 160-200 DEG C to obtain a rubber material subjected to dynamic vulcanization; and slitting and curing the dynamically vulcanized rubber material to obtain the silicone rubber product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polymer material processing, and particularly relates to a silicone rubber product and a preparation method and application thereof. BACKGROUND

[0002] In the related art, the hydrophilic modification (such as introducing polar groups such as hydroxyl groups and carboxyl groups) is performed on the silicone rubber to improve the properties such as antistatic property and biocompatibility.

[0003] However, this can cause the hydrogen bond interaction between the molecular chains to be enhanced, the melt viscosity to be significantly increased, and thus the processing difficulty and the product performance deterioration to be caused. SUMMARY

[0004] Therefore, the present application provides a silicone rubber product and a preparation method and application thereof.

[0005] According to an embodiment of the present application, a method for preparing a silicone rubber product based on dynamic vulcanization is provided, including the following steps:

[0006] The raw silicone rubber, the amphiphilic block copolymer, the dynamic crosslinking agent and the nano filler are mixed to obtain a premixed rubber compound;

[0007] The premixed rubber compound is dynamically vulcanized at 160 DEG C to 200 DEG C to obtain a dynamically vulcanized rubber compound;

[0008] The dynamically vulcanized rubber compound is cut and cured to obtain the silicone rubber product.

[0009] In some embodiments of the present application, the shear rate of the dynamic vulcanization is 50 s -1 ~300 s -1 , and the time is 2 min to 5 min.

[0010] In some embodiments of the present application, the crosslinking degree of the dynamically vulcanized rubber compound is 10% to 30%.

[0011] In some embodiments of the present application, the dynamically vulcanized rubber compound has a reversible physical crosslinking network.

[0012] In some embodiments of the present application, the amphiphilic block copolymer includes at least one of polydimethylsiloxane-b-polyacrylic acid and polyethylene oxide-b-polydimethylsiloxane.

[0013] In some embodiments of the present application, the mass content of the amphiphilic block copolymer is 3% to 10% based on the mass of the raw silicone rubber.

[0014] In some embodiments of the present application, the dynamic crosslinking agent includes a composite system of hydrogen-containing silicone oil and a platinum catalyst.

[0015] In some embodiments of the present application, the mass content of the hydrogen-containing silicone oil is 0.5wt% to 3wt%, and the mass content of the platinum catalyst is 10ppm to 50ppm, based on the mass of the raw silicone rubber.

[0016] In some embodiments of the present application, the nano-filler includes at least one of hydrophobically modified fumed silica and graphene.

[0017] In some embodiments of the present application, when the nano-filler includes hydrophobically modified fumed silica, the particle size of the hydrophobically modified fumed silica is 10nm to 50nm.

[0018] The mass content of the nano-filler is 1% to 5%, based on the mass of the raw silicone rubber.

[0019] In some embodiments of the present application, the melt mass flow rate of the dynamically vulcanized rubber compound is 14g / 10min to 18g / 10min, and the water contact angle is 50° to 60°.

[0020] According to embodiments of the second aspect of the present application, a silicone rubber product prepared based on the method of dynamically vulcanizing to prepare a silicone rubber product is provided.

[0021] According to embodiments of the third aspect of the present application, a cigarette filter rod is provided, which includes the silicone rubber product described above.

[0022] According to embodiments of the fourth aspect of the present application, a cigarette is provided, which includes the cigarette filter rod described above.

[0023] The present application breaks through the contradiction between hydrophilic modification and processing fluidity through the synergistic strategy of “reversible crosslinking network + microphase separation”, and provides technical support for material upgrading in the fields of precision injection molding parts, thin-walled medical catheters, etc. The present application achieves a reduced melt viscosity: a reversible physical crosslinking network is formed by dynamic vulcanization ( Figure 1 ), which reduces the melt viscosity (corresponding to Table 1 high melt mass flow rate), and through the synergistic enhancement of nano-filler and dynamic vulcanization, the strength loss caused by hydrogen-containing silicone oil can be offset, and the mechanical properties (tensile strength ≥ 7 MPa) are maintained after network reconstruction, and the mechanical properties are stable; hydrophilic-hydrophobic microphase separation: amphiphilic block copolymers self-assemble to form nanoscale hydrophilic microdomains, which maintain hydrophilicity (water contact angle 50° to 60°) while avoiding excessive increase of hydrogen bonds between molecular chains, thereby maintaining high fluidity.

[0024] The application solves the processing problem caused by viscosity increase of hydrophilic modified silicone rubber by molecular structure design (introducing amphiphilic block copolymer) and process innovation (dynamic vulcanization), combined with nano filler, realizes the following goals: melt viscosity reduction: compared with traditional hydrophilic modified silicone rubber, the melt mass flow rate is increased, close to the level of unmodified silicone rubber; hydrophilicity is maintained: water contact angle ≤ 60°, meeting the application requirements of medical catheter, waterproof and breathable film, etc.; stable mechanical properties: tensile strength ≥ 7 MPa, elongation at break ≥ 350%. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and other objects, features and advantages of the present application will become more apparent from the following description of embodiments of the present application, taken in conjunction with the accompanying drawings, in which:

[0026] Figure 1 A dynamic vulcanization mechanism schematic diagram of the embodiments of the present application is shown.

[0027] Figure 2 A transmission electron microscope image of the amphiphilic block copolymer microphase separation structure of the dynamic vulcanized rubber provided by the embodiment 1 of the present application is shown. DETAILED DESCRIPTION

[0028] In the following, the embodiments of the present application will be described. However, it should be understood that these descriptions are only exemplary, and are not intended to limit the scope of the present application. In the following detailed description, many specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, it is apparent that one or more embodiments can be implemented without these specific details. In addition, in the following description, the description of well-known structures and techniques is omitted to avoid unnecessary confusion of the concepts of the present application.

[0029] The terms used herein are only for describing specific embodiments, and are not intended to limit the present application. The term "comprising" used herein indicates the presence of a feature, step, operation, but does not exclude the presence or addition of one or more other features.

[0030] In the case of using expressions similar to "at least one of A, B, and C, etc.", it is generally intended to include any of A, B, and C alone, or any combination of A, B, and C, etc. In the case of using expressions similar to "at least one of A, B, or C, etc.", it is generally intended to include any of A, B, and C alone, or any combination of A, B, and C, etc.

[0031] In the related art, the hydrophilic modification (such as introducing polar groups such as hydroxyl, carboxyl, etc.) of silicone rubber is performed to improve its antistatic property, biocompatibility, etc. However, this can cause the hydrogen bond interaction between molecular chains to be enhanced, the melt viscosity to be significantly increased, and the following problems to be caused: processing difficulty: high viscosity causes incomplete injection molding filling, rough extrusion surface, and the processing temperature or pressure needs to be increased, which increases energy consumption and equipment wear. Performance degradation: excessive shear causes molecular chain rupture, and the tensile strength of the finished product is reduced. Narrow process window: although traditional plasticizers (such as silicone oil) can reduce the viscosity to overcome the problem of narrow process window in processing, the plasticizers will migrate and precipitate during use or storage, and the long-term stability of the silicone rubber product is poor.

[0032] In some embodiments of the present application, hydrophilic modification is achieved by introducing dehydrated glycerol ether oxygen dimethyl silane groups, but the viscosity increase problem is not solved, and the processing conditions of high vacuum (-0.08 to -0.1 MPa) are harsh; fly ash is used as a fine particle filler to improve flowability and reduce frictional resistance in the processing process such as extrusion and injection molding, but it will reduce the transparency and flexibility of the material. Therefore, an innovative solution that takes into account hydrophilicity and processing flowability is urgently needed.

[0033] In the implementation of the present application, it is found that the processing problems caused by the viscosity increase of hydrophilically modified silicone rubber can be solved through molecular structure design and process innovation.

[0034] Specifically, according to an embodiment of one aspect of the present application, a method for preparing a silicone rubber product based on dynamic vulcanization is provided, including steps S10-S30.

[0035] In step S10, silicone rubber raw rubber, amphiphilic block copolymer, dynamic crosslinking agent, and nano filler are mixed to obtain a premixed rubber compound.

[0036] In step S20, the premixed rubber is dynamically vulcanized at 160-200°C to obtain a dynamically vulcanized rubber.

[0037] In step S30, the dynamically vulcanized rubber is cut and cured to obtain a silicone rubber product.

[0038] The present application breaks through the contradiction between hydrophilic modification and processing fluidity through the "reversible crosslinking network + microphase separation" synergistic strategy, and provides technical support for material upgrading in the fields of precision injection molded parts, thin-walled medical catheters, etc. The present application realizes the following: reduced melt viscosity: a reversible physical crosslinking network is formed by dynamic vulcanization ( Figure 1 ), which reduces the melt viscosity (corresponding to Table 1 high melt mass flow rate), and through synergistic enhancement of nanofiller and dynamic vulcanization, the strength loss caused by hydrogen-containing silicone oil can be offset, and the mechanical properties (tensile strength ≥ 7 MPa) are maintained after network reconstruction, and the mechanical properties are stable; hydrophilic-hydrophobic microphase separation: amphiphilic block copolymers self-assemble to form nanoscale hydrophilic microdomains, avoiding excessive increase in overall polarity.

[0039] The present application solves the processing problem caused by the increase in viscosity of hydrophilically modified silicone rubber through molecular structure design (introduction of amphiphilic block copolymer) and process innovation (dynamic vulcanization), combined with nanofiller, and achieves the following goals: reduced melt viscosity: compared with traditional hydrophilically modified silicone rubber, the melt mass flow rate is increased, close to the level of unmodified silicone rubber; hydrophilicity is maintained: water contact angle ≤ 60°, meeting the application requirements of medical catheters, waterproof and breathable membranes, etc.; stable mechanical properties: tensile strength ≥ 7 MPa, elongation at break ≥ 350%.

[0040] The present application does not particularly limit the specific material of the silicone rubber product, as long as it can achieve the purpose of the present application. In some embodiments of the present application, the silicone rubber product can meet the requirements of food contact safety, specific physical properties (such as temperature resistance), processing adaptability, etc. For example, the material of the silicone rubber product can be methyl vinyl silicone rubber, methyl silicone rubber, etc.

[0041] In some embodiments of the present application, at step S10, the amphiphilic block copolymer can be any amphiphilic block copolymer that can copolymerize with the raw silicone rubber. The molecular chain of the amphiphilic block copolymer can be connected by covalent bonds between two or more blocks (segments) with different chemical structures, and at least one of the blocks contains a hydrophilic segment and a hydrophobic segment. The present application does not have special restrictions on the amphiphilic block copolymer, as long as the purpose of the present application can be achieved. For example, the amphiphilic block copolymer can include at least one of polydimethylsiloxane-b-polyacrylic acid, polyethylene oxide-b-polydimethylsiloxane. Polydimethylsiloxane-b-polyacrylic acid, polyethylene oxide-b-polydimethylsiloxane can better self-assemble to form nanoscale hydrophilic microdomains, avoid excessive increase in overall polarity, and achieve hydrophilic-hydrophobic microphase separation. Adding the amphiphilic block copolymer polydimethylsiloxane-b-polyacrylic acid and / or polyethylene oxide-b-polydimethylsiloxane to the silicone rubber can achieve uniform dispersion with the polydimethylsiloxane segment in the molecular chain of the amphiphilic block copolymer, which is compatible with the silicone rubber. At the same time, the silicone rubber is endowed with interfacial modification ability through the hydrophilic polyacrylic acid and / or polyethylene oxide segment, effectively improving the compatibility and bonding performance of the silicone rubber with polar materials; in addition, such copolymer can regulate the surface energy of the silicone rubber, improve the wettability of the material, and also enhance the mechanical properties of the silicone rubber without significantly reducing the excellent properties of the original silicone rubber, such as high and low temperature resistance, aging resistance, etc.

[0042] Based on the mass of the raw silicone rubber, the mass content of the amphiphilic block copolymer can be 3% to 10%. For example, based on the mass of the raw silicone rubber, the mass content of the amphiphilic block copolymer can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any range between any two of the above values. If the mass content of the amphiphilic block copolymer is too low, the amphiphilic block copolymer is difficult to form an effective network or interfacial action, and cannot fully exert the modification effect; if the content is too high, it may cause phase separation due to excessive intermolecular aggregation, thereby destroying the uniformity of the silicone rubber and even reducing its mechanical properties and stability. Only when the content is within the above range, the amphiphilic block copolymer can achieve a balance between dispersibility and functionality, maximize its modification gain for the silicone rubber, and ensure that the comprehensive performance of the material is optimized.

[0043] The dynamic crosslinking agent can include a composite system of hydrogen-containing silicone oil and platinum catalyst. The dynamic crosslinking agent including a composite system of hydrogen-containing silicone oil and platinum catalyst has mild reaction conditions, easy to control crosslinking rate, high reaction selectivity, and less by-products, which can reduce the adverse effects on the performance of the silicone rubber; at the same time, the Si-C bond formed during the crosslinking process has high bond energy, so that the vulcanized silicone rubber has excellent high and low temperature resistance, aging resistance and chemical stability, and the mechanical properties are more balanced.

[0044] The mass content of the hydrogen-containing silicone oil can be 0.5wt% to 3wt% based on the mass of the raw silicone rubber, and the mass content of the platinum catalyst can be 10ppm to 50ppm. Illustratively, the mass content of the hydrogen-containing silicone oil can be 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt%, 3.0wt% or a range between any two of the foregoing values based on the mass of the raw silicone rubber. The mass content of the platinum catalyst can be 10ppm, 15ppm, 20ppm, 25ppm, 30ppm, 35ppm, 40ppm, 45ppm, 50ppm or a range between any two of the foregoing values. The mass content of the hydrogen-containing silicone oil and the platinum catalyst within the foregoing ranges can allow the silicone rubber product to have a suitable crosslinking density and improve the performance of the silicone rubber product.

[0045] In some embodiments of the present application, the nanofiller can include at least one of hydrophobically-modified fumed silica and graphene. In the case where the nanofiller includes hydrophobically-modified fumed silica, the particle size of the hydrophobically-modified fumed silica can be 10nm to 50nm. Illustratively, the particle size of the hydrophobically-modified fumed silica can be 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm or a range between any two of the foregoing values. The mass content of the nanofiller can be 1% to 5% based on the mass of the raw silicone rubber. Illustratively, the mass content of the nanofiller can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or a range between any two of the foregoing values based on the mass of the raw silicone rubber. The particle size and mass content of the nanofiller within the foregoing ranges can enhance its synergistic effect with the dynamic vulcanization and improve the performance of the silicone rubber product.

[0046] The present application does not particularly limit the manner of hydrophobic modification of the hydrophobically-modified fumed silica, as long as the purpose of the present application can be achieved. For example, the manner of hydrophobic modification can include: forming a covalent bond by reacting a silane coupling agent (such as methylchlorosilane, dimethyldichlorosilane, etc.) with the surface hydroxyl groups of the silica; forming a coating layer by treating with a siloxane (such as polydimethylsiloxane); esterification or adsorption with alcohol, fatty acid and derivatives thereof, etc. with the surface hydroxyl groups; plasma treatment, etc. to achieve hydrophobicity by introducing hydrophobic groups (such as methyl, alkyl, etc.) onto the surface of the silica; and directly purchasing commercially available hydrophobically-modified fumed silica, etc.

[0047] In some embodiments of the present application, the temperature of the dynamic vulcanization can be 160°C to 200°C and the shear rate can be 50s -1 ~300s -1The time can be 2 to 5 minutes. The preferred temperature for dynamic vulcanization is 170°C to 185°C. For example, the temperature for dynamic vulcanization can be any two values ​​between 160°C, 170°C, 180°C, 185°C, 190°C, 200°C, and above, and the shear rate can be 50 s. -1 100s -1 150s -1 200s -1 250s -1 300s -1 The time can be any two of the above values, or a range between any two of them. The time can be 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min, 5 min, or any two of the above values. When the temperature, shear rate, and time of dynamic vulcanization are within the above ranges, the reversible cross-linked network formed by dynamic vulcanization can be better dissociated under processing shear, thus improving the melt flow rate.

[0048] In some embodiments of this application, the degree of crosslinking of the dynamically vulcanized rubber compound can be 10%-30%. Exemplarily, the degree of crosslinking of the dynamically vulcanized rubber compound can be within the range of any two values ​​of 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, or higher. The dynamically vulcanized rubber compound has a reversible physical crosslinking network.

[0049] In some embodiments of this application, the melt flow rate of the dynamically vulcanized rubber compound can be from 14 g / 10 min to 18 g / 10 min, and the water contact angle can be from 50° to 60°. Exemplarily, the melt flow rate of the dynamically vulcanized rubber compound can be within the range of any two of the following values: 14 g / 10 min, 15 g / 10 min, 16 g / 10 min, 17 g / 10 min, 18 g / 10 min, or more. The water contact angle can be within the range of any two of the following values: 50°, 51°, 52°, 53°, 54°, 55°, 56°, 57°, 58°, 59°, 60°, or more.

[0050] Figure 1 A schematic diagram of the dynamic vulcanization mechanism of an embodiment of this application is shown. Wherein, (a) is the unvulcanized premixed rubber compound, and (b) is the dynamically vulcanized rubber compound. Figure 1 It can be seen that the linear molecular chains of the uncured premixed rubber are randomly distributed; the dynamically cured rubber forms reversible cross-linking points (red nodes), which dissociate under shear.

[0051] The specific process of the slitting and curing in step S30 is not particularly limited in the present application, as long as the purpose of the present application can be achieved. For example, it can be first formed by injection molding or extrusion molding, and then slitting and second curing (or post-curing or second vulcanization). In step S30, the structure and material of the molding die are not particularly limited in the present application, as long as the purpose of the present application can be achieved. Related skilled persons can select appropriate molds according to actual needs to prepare suitable silicone rubber products. For example, the material of the mold can include metal (such as aluminum alloy, die steel), silicone, resin, etc. Among them, the metal mold has high strength, high wear resistance and long service life, is suitable for mass production of high-precision products, and can be manufactured by CNC processing, electric spark forming and other processes to manufacture complex cavities; the silicone mold is suitable for small batch trial production or complex shaped products due to its short production cycle, low cost and good flexibility, and can accurately reproduce the details of the prototype; the resin mold is between the two, and has certain accuracy and economy.

[0052] In some embodiments of the present application, the temperature of the second curing can be 190°C to 210°C, and the time can be 0.5h to 1.5h. Exemplarily, the temperature of the second curing can be 190°C, 192°C, 195°C, 198°C, 200°C, 202°C, 205°C, 208°C, 210°C, or a range between any two of the above values, and the time can be 0.5h, 0.8h, 1.0h, 1.2h, 1.5h, or a range between any two of the above values.

[0053] According to the embodiments of the second aspect of the present application, a silicone rubber product prepared based on the above method for preparing a silicone rubber product by dynamic vulcanization is provided. The silicone rubber product provided by the embodiments of the present application can have both hydrophilicity and processing fluidity.

[0054] The structure of the rubber product is not particularly limited in the present application, as long as the purpose of the present application can be achieved. Related skilled persons can design silicone rubber products with different structures according to actual needs.

[0055] According to the embodiments of the third aspect of the present application, a cigarette filter rod is provided, which comprises the above-mentioned silicone rubber product. The cigarette filter rod provided by the present application has no static accumulation, so that the cigarette filter rod is not easy to adsorb tobacco powder near the lip end, and the consumer has a better experience during use. The cigarette filter rod can have both antistatic property and processing fluidity.

[0056] The specific structure of the silicone rubber product for the cigarette filter rod is not particularly limited in the present application, as long as the purpose of the present application can be achieved. Different structures of the silicone rubber product can be designed according to different needs of the cigarette filter rod. For example, the silicone rubber product can be a silicone rubber cylinder, which can include a first through hole and a second through hole parallel to the axis, wherein the diameter of the first through hole can be greater than that of the second through hole, and the first through hole is located at the center of the silicone rubber cylinder, and a plurality of second through holes are uniformly distributed along the circumference of the silicone rubber cylinder.

[0057] The specific structure of the cigarette filter rod is not particularly limited in the present application, as long as the purpose of the present application can be achieved. Different structures of the cigarette filter rod can be designed according to different needs of the cigarette filter rod. For example, the cigarette filter rod can include a silicone rubber product, a cured adhesive, and a forming paper. The silicone rubber product and the forming paper are bonded by the adhesive.

[0058] According to the embodiment of the fourth aspect of the present application, a cigarette is provided, which includes the cigarette filter rod described above.

[0059] The type of cigarette is not particularly limited in the present application, as long as the purpose of the present application can be achieved. Illustratively, the cigarette in the present application can be a conventional combustion cigarette, or a heat-not-burn cigarette. In the case where the cigarette is a conventional combustion cigarette, the conventional combustion cigarette can further include a tobacco segment. In the case where the cigarette is a heat-not-burn cigarette, the heat-not-burn cigarette can further include a smoking segment, a support segment, a temperature-lowering segment, etc.

[0060] The present application will be described in detail below with reference to the embodiments, so as to facilitate the understanding of the present application by those skilled in the art. It is necessary to point out here that the embodiments are only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application. The relevant skilled person can make non-essential improvements and adjustments to the present application according to the above disclosure, which should still fall within the protection scope of the present application. Meanwhile, the raw materials mentioned below are not described in detail, which are all commercially available products; the process steps or preparation methods not mentioned in detail are all known process steps or preparation methods to the relevant skilled person.

[0061] Example 1

[0062] The present embodiment provides an antistatic silicone rubber product and a preparation method thereof, which includes the following steps:

[0063] (1) 100 parts by mass of methyl vinyl silicone rubber raw rubber, 8 parts by mass of amphiphilic block copolymer polydimethylsiloxane-b-polyacrylic acid, and 4 parts by mass of nano filler are mixed in a mixer at 90°C for 20 minutes. The nano filler is hydrophobic fumed silica (Aerosil R812).

[0064] The dynamic crosslinking agent is added, and mixing is continued for 5 minutes to obtain a premixed rubber. The dynamic crosslinking agent comprises 2 parts by mass of hydrogen-containing silicone oil (hydrogen content 0.8%) and 30 ppm of platinum catalyst (Karstedt catalyst).

[0065] (2) The premixed rubber is fed into a twin-screw extruder (L / D = 40) for dynamic vulcanization, with a temperature setting of 185°C and a screw rotation speed of 200 rpm, to obtain dynamically vulcanized rubber.

[0066] (3) The dynamically vulcanized rubber is extruded, cut, and cured at 200°C for 1 hour to obtain a silicone rubber product.

[0067] Figure 2 A transmission electron microscope image of the microphase separation structure of the amphiphilic block copolymer of the silicone rubber product provided in Embodiment 1 is shown. The dark region A is a polydimethylsiloxane phase (hydrophobic), and the light region B is a polyacrylic acid phase (hydrophilic). Figure 2 It can be seen that in Embodiment 1, the amphiphilic block copolymer self-assembles to form a nanoscale hydrophilic microregion, and the hydrophilic-hydrophobic microphase separates.

[0068] Embodiment 2

[0069] The present embodiment provides an antistatic silicone rubber product and a preparation method thereof, comprising the following steps:

[0070] (1) 100 parts by mass of methyl vinyl silicone rubber raw rubber, 6 parts by mass of amphiphilic block copolymer polyethylene oxide-b-polydimethylsiloxane, and 3 parts by mass of nano filler are mixed in a Banbury mixer at 90°C for 20 minutes. The nano filler is hydrophobized fumed silica (Aerosil R812).

[0071] The dynamic crosslinking agent is added, and mixing is continued for 5 minutes to obtain a premixed rubber. The dynamic crosslinking agent comprises 2 parts by mass of hydrogen-containing silicone oil (hydrogen content 0.8%) and 30 ppm of platinum catalyst (Karstedt catalyst).

[0072] (2) The premixed rubber is fed into a twin-screw extruder (L / D = 40) for dynamic vulcanization, with a temperature setting of 160°C and a screw rotation speed of 250 rpm, to obtain dynamically vulcanized rubber.

[0073] (3) The dynamically vulcanized rubber is extruded, cut, and cured at 200°C for 1 hour to obtain a silicone rubber product.

[0074] Embodiment 3

[0075] The present embodiment provides an antistatic silicone rubber product and a preparation method thereof, which is similar to Embodiment 1, except that in step (2), the dynamic vulcanization temperature is 200°C.

[0076] Comparative Example 1

[0077] This comparative example provides an antistatic silicone rubber product and a method for preparing the same, referring to Example 1, except that in step (1), the amphiphilic block copolymer polydimethylsiloxane-b-polyacrylic acid is replaced with equal mass parts of polyvinyl alcohol-4000.

[0078] Comparative Example 2

[0079] This comparative example provides an antistatic silicone rubber product and a method for preparing the same, referring to Example 1, except that in step (1), no dynamic crosslinking agent is added.

[0080] Comparative Example 3

[0081] This comparative example provides an antistatic silicone rubber product and a method for preparing the same, referring to Example 1, except that in step (1), the dynamic crosslinking agent is replaced with equal mass parts of the crosslinking agent dicumyl peroxide.

[0082] Comparative Example 4

[0083] This comparative example provides an antistatic silicone rubber product and a method for preparing the same, referring to Example 1, except that in step (1), the amphiphilic block copolymer polydimethylsiloxane-b-polyacrylic acid is replaced with equal mass parts of polyvinyl alcohol-4000, and no dynamic crosslinking agent is added.

[0084] Comparative Example 5

[0085] This comparative example provides an antistatic silicone rubber product and a method for preparing the same, referring to Example 1, except that in step (1), no nano-filler is added.

[0086] Comparative Example 6

[0087] This comparative example provides an antistatic silicone rubber product and a method for preparing the same, referring to Example 1, except that in step (2), the temperature for dynamic vulcanization is 240°C.

[0088] Comparative Example 7

[0089] This comparative example provides an antistatic silicone rubber product and a method for preparing the same, referring to Example 1, except that in step (2), the temperature for dynamic vulcanization is 140°C.

[0090] The dynamic vulcanized rubber provided by Example 1 to Example 3, Comparative Example 1 to Comparative Example 7 is subjected to melt mass flow rate test, and the silicone rubber product is subjected to water contact angle test, tensile strength test, 250℃ oven aging tensile strength test and extrusion surface roughness test, wherein the melt mass flow rate test is carried out according to the standard GB / T 3682.1-2018 “Plastics Determination of the melt mass-flow rate (MFR) and the melt volume-flow rate (MVR) of thermoplastics”. The water contact angle test is carried out according to the standard GB / T 30693-2014 “Plastics Determination of the water contact angle of plastic films”. The tensile strength test is carried out according to the standard GB / T 528-2009 “Vulcanized or thermoplastic rubber Determination of tensile stress-strain properties”. The 250℃ oven aging tensile strength test is carried out according to the standard ISO 11346-2014 “Vulcanized or thermoplastic rubber Assessment of service life and maximum service temperature”, 250℃ treatment for 3 hours. The extrusion surface roughness test is carried out according to the standard GB / T 1031-2009 “Geometrical product specifications (GPS) Surface structure Profile method Parameters of surface roughness and their values”. The relevant test results are shown in Table 1.

[0091] Table 1

[0092]

[0093] Note: “ / ” in Table 1 indicates that the test is not performed.

[0094] As shown in Table 1, the melt mass flow rate of the silicone rubber product provided by the embodiments of the present application is between 14 g / 10min and 18 g / 10min, the water contact angle is between 50° and 60°, and the tensile strength is ≥7 MPa. The preparation method of the silicone rubber product provided by the embodiments of the present application significantly improves the flowability while maintaining good hydrophilicity and mechanical strength.

[0095] Among them, Comparative Example 1 uses a traditional plasticizer, the tensile strength is reduced and the long-term stability is poor. Comparative Example 2 does not form a reversible physical crosslinking network, the melt mass flow rate decreases, and the processing flowability is poor. In Comparative Example 3, the dynamic crosslinking agent is replaced by dicumyl peroxide, the water contact angle becomes smaller, the tensile strength decreases, and the tensile strength retention rate after aging is detected <60%. In Comparative Example 4, no dynamic crosslinking agent is added, the melt mass flow rate is low, the tensile strength decreases, and the surface roughness is high. In Comparative Example 5, no nano filler is added, the strength loss caused by the plasticizer is not offset, so the tensile strength decreases. In Comparative Example 6, the temperature of dynamic crosslinking is too high, the crosslinking is excessive, and the extruder equipment is overloaded. In Comparative Example 7, the temperature of dynamic crosslinking is too low, and the tensile strength is low.

[0096] The above-described specific embodiments further illustrate the purposes, technical solutions and beneficial effects of the present application, and it should be understood that the above-described specific embodiments are merely for the specific embodiments of the present application and are not intended to limit the present application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing a silicone rubber article based on dynamic vulcanization, characterized by, The method comprises the following steps: mixing raw silicone rubber, amphiphilic block copolymer, dynamic crosslinking agent and nano filler to obtain a premix; dynamically vulcanizing the premix at 160-200℃ to obtain a dynamically vulcanized rubber; cutting and curing the dynamically vulcanized rubber to obtain a silicone rubber product.

2. The method for producing a silicone rubber article by dynamic vulcanization according to claim 1, characterized by, The dynamic vulcanization has a shear rate of 50 s -1 ~300 s -1 , and a time of 2 min~5 min.

3. The method for producing a silicone rubber article by dynamic vulcanization according to claim 2, characterized by, The dynamically vulcanized rubber has a crosslinking degree of 10-30%. The dynamically vulcanized rubber has a reversible physical crosslinking network.

4. The method for producing a silicone rubber article by dynamic vulcanization according to claim 1, characterized by, The amphiphilic block copolymer comprises at least one of polydimethylsiloxane-b-polyacrylic acid and polyethylene oxide-b-polydimethylsiloxane. The mass content of the amphiphilic block copolymer is 3-10% based on the mass of the raw silicone rubber.

5. The method for producing a silicone rubber article by dynamic vulcanization according to claim 1, characterized by, The dynamic crosslinking agent comprises a composite system of hydrogen-containing silicone oil and platinum catalyst. The mass content of the hydrogen-containing silicone oil is 0.5-3wt% and the mass content of the platinum catalyst is 10-50ppm based on the mass of the raw silicone rubber.

6. The method for producing a silicone rubber article by dynamic vulcanization according to claim 1, characterized by, The nano filler comprises at least one of hydrophobically modified fumed silica and graphene. When the nano filler comprises hydrophobically modified fumed silica, the particle size of the hydrophobically modified fumed silica is 10-50nm. The mass content of the nano filler is 1-5% based on the mass of the raw silicone rubber.

7. The method for producing a silicone rubber article by dynamic vulcanization according to any one of claims 1 to 6, characterized in that, The melt mass flow rate of the dynamically vulcanized rubber is 14-18g / 10min and the water contact angle is 50-60°.

8. A silicone rubber product prepared by the method of any one of claims 1-7.

9. A cigarette filter rod, characterized by, The cigarette filter rod comprises the silicone rubber product of claim 8.

10. A cigarette, characterized by The cigarette comprises the cigarette filter rod of claim 9.

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