Fluororubber aramid fiber composite material and preparation method thereof

Abstract

The invention discloses a fluororubber and aramid fiber composite material which comprises the following components in parts by weight: 100 parts of fluororubber, 2-3 parts of 2, 2-bis-(4-hydroxyphenyl) hexafluoropropane, 0.5-2 parts of benzyltriphenylphosphonium chloride, 3-5 parts of magnesium oxide, 5-8 parts of calcium hydroxide, 20-35 parts of barium sulfate, 3-5 parts of iron oxide red, 1-8 parts of aramid fiber, 0.1-1 part of a water-soluble polyphenol compound and 3-10 parts of a dispersing aid. The invention also discloses a preparation method of the fluororubber and aramid fiber composite material, which comprises the following steps: shearing and stripping the aramid fiber, performing surface modification, hybridizing and drying with the silica powder, mixing the hybridized aramid fiber into the fluororubber through an internal mixer and an open mill, and finally performing two-stage vulcanization to obtain the composite material. The invention solves the problems of poor physical and mechanical properties of the material and easy agglomeration of the aramid fiber in the fluororubber caused by weak interface action of the fluororubber and the aramid fiber in the prior art, and further improves the tensile property, tearing property, compression set, thermo-oxidative aging resistance and oil resistance of the fluororubber.

Description

Technical Field

[0001] This invention relates to the field of rubber modification technology, and in particular to a fluororubber-aramid fiber composite material and its preparation method. Background Technology

[0002] Fluororubber possesses a saturated main chain protected by tightly packed, electron-withdrawing fluorine atoms on its side groups. This structural feature endows fluororubber with excellent resistance to high temperatures, oxidation, solvents, and chemicals. It is commonly used to manufacture seals and gaskets, and is widely applied in cutting-edge technology fields such as aerospace, rail transportation, and oil and gas extraction, earning it the title of "King of Rubbers." However, due to its poor physical and mechanical properties, fluororubber often fails to meet application requirements. Therefore, inorganic fillers such as carbon black, silica, and barium sulfate are added for reinforcement and modification during its application. Furthermore, due to the molecular inertness and low surface energy of fluororubber, the interfacial interactions between fluororubber and most fillers are weak, resulting in unsatisfactory physical and mechanical properties.

[0003] Aramid fibers have attracted widespread attention in the field of rubber modification due to their high aspect ratio, high specific strength, wear resistance, and high temperature resistance. However, research has revealed several challenges in the composite modification process of aramid fibers with fluororubber: Due to the high aspect ratio and specific surface area of ​​aramid fibers, as well as the strong interactions and entanglement between fibers, aramid fibers are difficult to disperse uniformly in the fluororubber matrix, easily forming aggregates. Furthermore, the high surface smoothness and chemical inertness of aramid fibers make it difficult to form strong interfacial interactions with the rubber matrix, hindering the acquisition of fluororubber-aramid fiber composites with good physical and mechanical properties.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] To address the shortcomings of the aforementioned technologies, this invention provides a fluororubber-aramid fiber composite material and its preparation method. By using water-soluble polyphenol compounds as surface-modifying agents for aramid fibers, the water-phase environmentally friendly modification of aramid fibers is achieved. Furthermore, the polyphenol compounds can participate in the vulcanization of fluororubber, fixing the fluororubber molecular chains onto the surface of the aramid fibers, thereby improving the interfacial interaction between fluororubber and aramid fibers. In addition, low-polarity silica micropowder with low surface hydroxyl content is used to hybridize and isolate the peeled and modified aramid fibers, preventing them from re-agglomerating during drying and improving the uniform dispersion of aramid fibers during the subsequent fluororubber compounding process.

[0006] The specific technical solution proposed in this invention is as follows:

[0007] On one hand, this invention discloses a fluororubber-aramid fiber composite material, comprising the following raw materials in parts by weight:

[0008] 100 parts of fluororubber, 2-3 parts of 2,2-bis-(4-hydroxyphenyl)hexafluoropropane, 0.5-2 parts of benzyltriphenylphosphine chloride, 8-13 parts of heat stabilizer-acid absorbent system, 20-35 parts of functional filler, 3-5 parts of iron oxide red, 1-8 parts of aramid fiber, 0.1-1 parts of water-soluble polyphenol compound, and 3-10 parts of dispersing agent.

[0009] Furthermore, the fluororubber is at least one of type 23 fluororubber, type 26 fluororubber, type 246 fluororubber, TP type fluororubber, polyvinylidene fluoride rubber, perfluoroether rubber, and fluorosilicone rubber.

[0010] Furthermore, the aramid fiber is at least one of aramid pulp and chopped aramid fiber, and the length of the aramid fiber is 0.5-30 mm.

[0011] Furthermore, the heat stabilizer-acid absorbent system includes magnesium oxide and / or calcium hydroxide.

[0012] Furthermore, the functional filler is at least one of barium sulfate and calcium carbonate.

[0013] Furthermore, the water-soluble polyphenol compound is tannic acid.

[0014] Furthermore, the dispersing agent is at least one of microsilica powder or silicon micropowder.

[0015] On the other hand, the present invention also discloses a method for preparing a fluororubber-aramid fiber composite material, comprising the following steps:

[0016] (1) Prepare an aqueous solution of tannic acid, add aramid fiber for shearing and peeling, then add a dispersing agent and continue shearing and mixing. After standing and layering, filtering and vacuum drying, the hybrid filler is obtained.

[0017] (2) Fluororubber, functional filler, iron oxide red, heat stabilizer-acid absorber system are added to internal mixer for first mixing, then the obtained hybrid filler is added for second mixing, and finally 2,2-bis-(4-hydroxyphenyl)hexafluoropropane and benzyltriphenylphosphine chloride are added for third mixing. The glue is discharged to obtain compound rubber one.

[0018] (3) Place the first compound rubber in a two-roll mill for two-roll milling. After the compound rubber wraps around the rollers, cut the rubber and perform triangular wrapping. Cut the rubber into sheets to obtain the second compound rubber.

[0019] (4) Cool the compound rubber and let it stand for a preset time, then vulcanize it in a two-stage vulcanization process to obtain the fluororubber aramid fiber composite material.

[0020] Furthermore, the shearing and stripping parameters include: stator-rotor type high-speed homogenizer shearing and stripping, rotation speed 5000-10000 r / min, time 10-30 min; the shearing and mixing parameters include: stator-rotor type high-speed homogenizer shearing and mixing, rotation speed 1000-6000 r / min, time 10-30 min.

[0021] Furthermore, the two-stage vulcanization method includes: the first stage vulcanization using a flat vulcanizing machine at 170-180 degrees Celsius. o Vulcanization at 10-20 MPa for 5-20 min; secondary vulcanization is carried out in an oven at 200-230°C. o Bake at C for 12-36 hours.

[0022] Compared with existing technologies, the fluororubber-aramid fiber composite material and its preparation method proposed in this invention have the following beneficial technical effects:

[0023] (1) In this invention, water-soluble polyphenol compounds are selected as surface modification agents for aramid fibers, which can modify and improve the dispersion uniformity of aramid fibers in fluororubber and their interfacial interaction with fluororubber; further, tannic acid is used as a water-soluble polyphenol compound. On the one hand, tannic acid forms strong hydrogen bonds with the surface of aramid fibers and is firmly adsorbed on the surface of aramid fibers. On the other hand, tannic acid can participate in the crosslinking of fluororubber, thereby improving the interfacial interaction between fluororubber and aramid fibers.

[0024] (2) Using silica powder (or microsilica powder) that can improve the flowability of polymer materials and the dispersibility of fillers as a physical separator for aramid fibers, the silica powder (or microsilica powder) and aramid fibers are hybridized by high-speed liquid phase shearing to achieve uniform dispersion of aramid fibers in fluororubber, thereby improving the processing flowability of fluororubber and the dispersion uniformity of aramid fibers.

[0025] By using tannic acid as a surface-modifying agent for aramid fibers and adding dispersing agents, the tensile properties, compression set, heat and oxygen aging resistance, and oil resistance of fluororubber are significantly improved. Attached Figure Description

[0026] Figure 1 These are microscope images of the fluororubber-aramid fiber composite material prepared in Example 1 of this invention;

[0027] Figure 2 This is a microscope image of the fluororubber-aramid fiber composite material prepared in Comparative Example 2 of this invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0029] The following describes, but is not limited to, the raw materials used in the embodiments and comparative examples of this application:

[0030] Fluororubber, Shandong Dongyue Polymer Materials Co., Ltd.;

[0031] 2,2-Bis-(4-hydroxyphenyl)hexafluoropropane (AF), benzyltriphenylphosphine chloride (BPP), Shandong Bojin New Materials Co., Ltd.;

[0032] Calcium hydroxide, Inoue Lime Industry Co., Ltd., Japan;

[0033] Silica powder (model XRD-W98), microsilica powder (model XRD-SP90), Qingdao Xinruida New Material Technology Co., Ltd.;

[0034] Aramid pulp, model SP30, Sinochem International High Performance Fiber Materials Co., Ltd.

[0035] Short-cut aramid fiber, 3 mm in length, from Yantai Taihexing Materials Technology Co., Ltd.

[0036] Tannic acid, barium sulfate, Aladdin reagent;

[0037] Iron oxide red, magnesium oxide, Qingdao Keling New Materials Technology Co., Ltd.

[0038] In some embodiments, the preparation method of the fluororubber-aramid fiber composite material provided by the present invention includes the following steps:

[0039] (1) Weighing of raw materials according to the formula: Weigh each material according to the formula;

[0040] (2) Modification and hybridization of aramid fibers: Prepare an aqueous solution of tannic acid, add aramid fibers for shearing and peeling, then add a dispersing agent for further shearing and mixing, and after static layering, filtration, and vacuum drying, the hybrid filler is obtained; further, the shearing and peeling parameters include: shearing and peeling with a stator-rotor type high-speed homogenizer, rotation speed 5000-10000 r / min, time 10-30 min; the shearing and mixing parameters include: shearing and mixing with a stator-rotor type high-speed homogenizer, rotation speed 1000-6000 r / min, time 10-30 min;

[0041] (3) Internal mixing: Fluororubber, functional filler, iron oxide red, heat stabilizer-acid absorbent system are added to internal mixer for the first mixing, then the obtained hybrid filler is added for the second mixing, and finally 2,2-bis-(4-hydroxyphenyl)hexafluoropropane and benzyltriphenylphosphine chloride are added for the third mixing. The glue is discharged to obtain compound rubber one.

[0042] (4) Open milling: Place the first compound rubber into the open mill for open milling. After the compound rubber wraps around the roller, cut the rubber and perform triangular wrapping. Sheet the rubber to obtain the second compound rubber.

[0043] (5) Vulcanization: The compound rubber is cooled and allowed to stand for a preset time, and then vulcanized in a two-stage vulcanization process to obtain the fluororubber-aramid fiber composite material; wherein the two-stage vulcanization process includes: the first stage vulcanization is carried out using a flat vulcanizing machine at 170-180°C. o Vulcanization at 10-20 MPa for 5-20 min; secondary vulcanization is carried out in an oven at 200-230°C. o Bake at C for 12-36 hours.

[0044] As an example of this application, the tannic acid concentration is 0.1-0.5 g / L. Preferably, the tannic acid concentration is 0.3 g / L.

[0045] As an embodiment of this application, in step (3), the conditions for the first mixing include: a first mixing temperature of 30-50°C. o C. The first mixing speed is 20-60 r / min, and the first mixing time is 3-5 min; the mixing temperature and speed of the second and third mixing are the same as those of the first mixing, the second mixing time is 3-8 min, and the third mixing time is 3-5 min.

[0046] Furthermore, in step (4), the temperature of the open mill is set to 25-40°C. o C; Rubber tapping and triangular wrapping treatment involves performing 6-8 rubber tapping operations and 6-8 triangular wrapping operations in sequence.

[0047] Furthermore, in step (5), the cooling and settling conditions before the vulcanization process include: a settling temperature of 25-40°C. o C. Settling time ≥ 6 hours.

[0048] Referring to the formulation table of fluororubber-aramid fiber composite materials in Table 1, unless otherwise specified, all the following examples were prepared using the above method.

[0049] The proportions of each group in Comparative Examples 1-4 and Examples 1-3 are shown in Table 1, and the corresponding properties of the obtained fluororubber-aramid fiber composite materials are shown in Table 2 below.

[0050] Table 1 Formulation of Fluororubber Aramid Fiber Composite Materials

[0051]

[0052] Table 2 Performance of Fluororubber Aramid Fiber Composites

[0053]

[0054] Specifically, the following detailed explanations are provided based on the formulations of the fluororubber aramid fiber composite materials in Table 1 (Comparative Examples 1-4 and Examples 1-3) and the properties of the fluororubber aramid fiber composite materials in Table 2 (Comparative Examples 1-4 and Examples 1-3).

[0055] Comparative Example 1

[0056] Without the addition of aramid fibers and silica powder, the prepared fluororubber material has poor physical and mechanical properties, with low values ​​for stress, tensile strength, stress at a given elongation, and tear strength.

[0057] Comparative Example 2

[0058] Compared with Comparative Example 1, Comparative Example 2 added aramid fibers, and the overall performance of the fluororubber composite material decreased. This is because the aramid fibers are difficult to disperse evenly and cannot form a strong interfacial bond with the fluororubber when added directly.

[0059] Comparative Example 3

[0060] Compared with Comparative Example 1, Comparative Example 3 added silica powder. In addition to a slight increase in tensile and tear properties, the compression set, heat and oxygen aging resistance and oil resistance all decreased slightly. This is because silica powder has only a weak reinforcing effect and a weak interfacial molecular interaction with fluororubber. At high temperatures, the fluororubber molecular chains at the interface will slip, resulting in the decrease of the above properties.

[0061] Comparative Example 4

[0062] Compared with Comparative Example 2, Comparative Example 4 added aramid fibers modified with tannic acid, and the overall performance of the fluororubber composite material was significantly improved. This is because tannic acid modification can improve the dispersion uniformity of aramid fibers in fluororubber and its interfacial interaction with fluororubber.

[0063] Example 1

[0064] Compared to Comparative Example 4, Example 1 added 5 parts of silica powder, which further improved the overall performance of the fluororubber composite material. This is because silica powder can improve the dispersion uniformity of aramid fibers in fluororubber. Furthermore, compared to Comparative Example 3, Example 1 added 3 parts of modified aramid fibers, which significantly improved the overall performance of the fluororubber composite material, further demonstrating the effectiveness of tannic acid-modified aramid fibers.

[0065] Example 2

[0066] Compared with Example 1, Example 2 increased the amount of aramid fiber, tannic acid and silica powder, further improving the overall performance of the fluororubber composite material.

[0067] Example 3

[0068] The types and amounts of aramid fibers, tannic acid, dispersing agents, and preparation process conditions of the fluororubber composite were adjusted. Compared with Comparative Example 1, the overall performance of the fluororubber composite was significantly improved.

[0069] Microscopic examination was performed on the materials prepared in Example 1 and Comparative Example 2, as shown in the attached figures. Figure 1 Microscopic images of the fluororubber-aramid fiber composite material prepared in Example 1 above; from the attached... Figure 1 As can be seen, after hybrid treatment with dispersing agent (silica powder), the fibers can be uniformly dispersed in the fluororubber matrix with less fiber agglomeration.

[0070] Appendix Figure 2 These are microscope images of the fluororubber-aramid fiber composite material prepared in Comparative Example 2 of this invention; from the attached... Figure 2 As can be seen, without the hybrid treatment of dispersing agents, the fibers cannot be uniformly dispersed in fluororubber, and the agglomeration is quite serious.

[0071] Compared with the prior art, the above embodiments of this application have the following beneficial technical effects:

[0072] (1) In this invention, water-soluble polyphenol compounds are selected as surface modification agents for aramid fibers, which can modify and improve the dispersion uniformity of aramid fibers in fluororubber and their interfacial interaction with fluororubber; further, tannic acid is used as a water-soluble polyphenol compound. On the one hand, tannic acid forms strong hydrogen bonds with the surface of aramid fibers and is firmly adsorbed on the surface of aramid fibers. On the other hand, tannic acid can participate in the crosslinking of fluororubber, thereby improving the interfacial interaction between fluororubber and aramid fibers.

[0073] (2) Using silica powder (or microsilica powder) that can improve the flowability of polymer materials and the dispersibility of fillers as a physical separator for aramid fibers, the silica powder (or microsilica powder) and aramid fibers are hybridized by high-speed liquid phase shearing to achieve uniform dispersion of aramid fibers in fluororubber, thereby improving the processing flowability of fluororubber and the dispersion uniformity of aramid fibers.

[0074] By using tannic acid as a surface-modifying agent for aramid fibers and adding dispersing agents, the tensile properties, compression set, heat and oxygen aging resistance, and oil resistance of fluororubber are significantly improved.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A fluororubber-aramid fiber composite material, characterized in that, The preparation materials include the following ingredients in parts by weight: 100 parts of fluororubber, 2-3 parts of 2,2-bis-(4-hydroxyphenyl)hexafluoropropane, 0.5-2 parts of benzyltriphenylphosphine chloride, 8-13 parts of heat stabilizer-acid absorbent system, 20-35 parts of functional filler, 3-5 parts of iron oxide red, 1-8 parts of aramid fiber, 0.1-1 parts of water-soluble polyphenol compound, and 3-10 parts of dispersing agent.

2. The fluororubber-aramid fiber composite material according to claim 1, characterized in that, The fluororubber is at least one of type 23 fluororubber, type 26 fluororubber, type 246 fluororubber, TP type fluororubber, polyvinylidene fluoride rubber, perfluoroether rubber, and fluorosilicone rubber.

3. The fluororubber-aramid fiber composite material according to claim 1, characterized in that, The aramid fiber is at least one of aramid pulp and chopped aramid fiber, and the length of the aramid fiber is 0.5-30 mm.

4. The fluororubber-aramid fiber composite material according to claim 3, characterized in that, The heat stabilizer-acid absorbent system includes magnesium oxide and / or calcium hydroxide.

5. The fluororubber-aramid fiber composite material according to claim 4, characterized in that, The functional filler is at least one of barium sulfate and calcium carbonate.

6. A fluororubber-aramid fiber composite material according to any one of claims 1-5, characterized in that, The water-soluble polyphenol compound is tannic acid.

7. The fluororubber-aramid fiber composite material according to claim 6, characterized in that, The dispersing agent is at least one of microsilica powder or silica powder.

8. A method for preparing a fluororubber-aramid fiber composite material, characterized in that, Includes the following steps: (1) Prepare an aqueous solution of tannic acid, add aramid fiber for shearing and peeling, then add a dispersing agent and continue shearing and mixing. After standing and layering, filtering and vacuum drying, the hybrid filler is obtained. (2) Fluororubber, functional filler, iron oxide red, heat stabilizer-acid absorber system are added to internal mixer for first mixing, then the obtained hybrid filler is added for second mixing, and finally 2,2-bis(4-hydroxyphenyl)hexafluoropropane and benzyltriphenylphosphine chloride are added for third mixing. The glue is discharged to obtain compound rubber one. (3) Place the first compound rubber in a two-roll mill for two-roll milling. After the compound rubber wraps around the rollers, cut the rubber and perform triangular wrapping. Cut the rubber into sheets to obtain the second compound rubber. (4) Cool the compound rubber and let it stand for a preset time, then vulcanize it in a two-stage vulcanization process to obtain the fluororubber aramid fiber composite material.

9. The method for preparing the fluororubber-aramid fiber composite material according to claim 8, characterized in that, The shearing and stripping parameters include: stator-rotor type high-speed homogenizer shearing and stripping, rotation speed 5000-10000 r / min, time 10-30 min; the shearing and mixing parameters include: stator-rotor type high-speed homogenizer shearing and mixing, rotation speed 1000-6000 r / min, time 10-30 min.

10. The method for preparing the fluororubber-aramid fiber composite material according to claim 8, characterized in that, The two-stage vulcanization method includes: the first stage vulcanization using a flat vulcanizing machine, at 170-180 degrees Celsius. o Vulcanization at 10-20 MPa for 5-20 min; secondary vulcanization is carried out in an oven at 200-230°C. o Bake at C for 12-36 hours.

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