Fluororubber aramid fiber composite material and preparation method thereof

Abstract

The application discloses a kind of fluorine rubber aramid fiber composite materials, including the following weight parts of component: fluorine rubber 100 parts, 2,2‑bis‑(4‑hydroxyphenyl) hexafluoropropane 2‑3 parts, benzyl triphenyl phosphonium chloride 0.5‑2 parts, magnesium oxide 3‑5 parts, calcium hydroxide 5‑8 parts, barium sulfate 20‑35 parts, iron red 3‑5 parts, aramid fiber 1‑8 parts, water-soluble polyphenol compound 0.1‑1 part, dispersion aid 3‑10 parts.The application also discloses the preparation method of fluorine rubber aramid fiber composite material, including aramid fiber shear peeling and surface modification, then with silicon powder hybridization dry, and then through internal mixer and open mill, hybrid aramid fiber is mixed into fluorine rubber, finally, the composite material is prepared by two-stage vulcanization.The application solves the problem that the interface of fluorine rubber and aramid fiber in the prior art is weak, which leads to poor physical and mechanical properties of the material, and aramid fiber is easy to agglomerate in fluorine rubber, thereby improving the tensile properties, tear resistance, compression set, heat and oxygen aging resistance and oil resistance of fluorine rubber.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber modification, and particularly relates to a fluorine rubber aramid fiber composite material and a preparation method thereof. BACKGROUND

[0002] The fluorine rubber has a saturated main chain, and the main chain is protected by strong electron-attracting fluorine atoms closely arranged on side groups, which endows the fluorine rubber with excellent high-temperature resistance, oxidation resistance, solvent resistance and chemical resistance, and the fluorine rubber is commonly used to make sealing elements and gaskets and is widely applied to fields of high technology such as aerospace, rail transit and oil and gas exploitation and is known as the 'rubber king'. However, the fluorine rubber is difficult to meet the use requirements due to poor physical and mechanical properties, and in the application process of the fluorine rubber, inorganic fillers such as carbon black, white carbon black and barium sulfate need to be added to reinforce and modify the fluorine rubber. In addition, due to the molecular inertness and low surface energy of the fluorine rubber, the interface interaction between the fluorine rubber and most fillers is weak, resulting in poor physical and mechanical properties of the fluorine rubber.

[0003] The aramid fiber is widely concerned in the field of rubber modification due to its high aspect ratio, high specific strength, wear resistance and high-temperature resistance. It is found in research that there are some problems in the process of composite modification of the aramid fiber and the fluorine rubber. Due to the high aspect ratio and high specific surface area of the aramid fiber and the strong interaction and entanglement between the fibers, the aramid fiber is difficult to uniformly disperse in the fluorine rubber matrix and is easy to form agglomerates in the rubber matrix. In addition, due to the high surface smoothness and chemical inertness of the aramid fiber, the aramid fiber is difficult to form a strong interface interaction with the rubber matrix, and it is difficult to obtain a fluorine rubber aramid fiber composite material with good physical and mechanical properties.

[0004] In view of this, the present application is provided. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a fluorine rubber aramid fiber composite material and a preparation method thereof. The water-soluble polyphenol compound is used as a surface modification aid of the aramid fiber to realize the water-based environmental modification of the aramid fiber, and the polyphenol compound can participate in the vulcanization of the fluorine rubber to fix the fluorine rubber molecular chain on the surface of the aramid fiber, so as to improve the interface interaction between the fluorine rubber and the aramid fiber. In addition, the low-polarity silicon powder with a small content of surface hydroxyl groups is used to hybridize and isolate the aramid fiber with good peeling modification, so as to prevent the aramid fiber from re-agglomerating in the drying process and improve the uniform dispersity of the aramid fiber in the later fluorine rubber mixing process.

[0006] The technical scheme provided by the present application is as follows:

[0007] On one hand, the present application discloses a fluorine rubber aramid fiber composite material, and the following preparation raw materials are included by weight fraction:

[0008] Fluororubber 100 parts, 2,2-bis-(4-hydroxyphenyl) hexafluoropropane 2-3 parts, benzyl triphenyl phosphonium chloride 0.5-2 parts, thermal stabilizer-acid absorbent system 8-13 parts, functional filler 20-35 parts, iron red 3-5 parts, aramid fiber 1-8 parts, water-soluble polyphenol compound 0.1-1 parts, dispersion aid 3-10 parts.

[0009] Further, the fluororubber is at least one of 23 type fluororubber, 26 type fluororubber, 246 type fluororubber, TP type fluororubber, perfluorinated ether rubber, perfluorinated ether rubber, perfluorinated ether rubber, fluorosilicone rubber.

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

[0011] Further, the thermal stabilizer-acid absorbent system comprises magnesium oxide and / or calcium hydroxide.

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

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

[0014] Further, the dispersion aid is at least one of microsilica and silica powder.

[0015] In another aspect, the present application also discloses a preparation method of fluororubber aramid fiber composite material, comprising the following steps:

[0016] (1) Prepare a tannic acid aqueous solution, add aramid fiber for shearing peeling, then add dispersion aid for continuous shearing mixing, after standing, filtering, vacuum drying, the hybrid filler is obtained;

[0017] (2) Add fluororubber, functional filler, iron red, thermal stabilizer-acid absorbent system to the internal mixer for first mixing, then add the obtained hybrid filler for second mixing, finally add 2,2-bis-(4-hydroxyphenyl) hexafluoropropane and benzyl triphenyl phosphonium chloride for third mixing, and discharge glue, to obtain the first mixing rubber;

[0018] (3) Put the first mixing rubber on the open mill for open mixing, after the mixing rubber is wrapped on the roller, cut the rubber and perform triangle bag treatment, and then down the sheet, to obtain the second mixing rubber;

[0019] (4) Cool and stand the second mixing rubber for a preset time, then vulcanize by two-stage vulcanization method, to obtain the fluororubber aramid fiber composite material.

[0020] Further, the shearing and peeling parameters include: a stator-rotor type high-speed homogenizer shearing and peeling, a rotating speed of 5000-10000 r / min, and a time of 10-30 min; and the shearing and mixing parameters include: a stator-rotor type high-speed homogenizer shearing and mixing, a rotating speed of 1000-6000 r / min, and a time of 10-30 min.

[0021] Further, the two-stage vulcanization mode includes: the first-stage vulcanization is performed by using a flat vulcanizing machine, and the vulcanization is performed at 170-180 o C and 10-20 MPa for 5-20 min; and the second-stage vulcanization is performed by using an oven, and the vulcanization is performed at 200-230 o C for 12-36 h.

[0022] Compared with the prior art, the fluororubber aramid fiber composite material and the preparation method thereof have the following beneficial technical effects:

[0023] (1) The water-soluble polyphenol compound is selected as the surface modification aid of the aramid fiber, which can improve the dispersion uniformity of the aramid fiber in the fluororubber and the interfacial action between the aramid fiber and the fluororubber; the tannic acid is further used as the water-soluble polyphenol compound, which can be strongly adsorbed on the surface of the aramid fiber through strong hydrogen bonding, and can participate in the crosslinking of the fluororubber, thereby improving the interfacial action between the fluororubber and the aramid fiber;

[0024] (2) The silicon powder (or micro silicon powder) capable of improving the flowability of the high polymer material and the dispersion of the filler is used as the physical isolation agent of the aramid fiber, and the silicon powder (or micro silicon powder) and the aramid fiber are hybridized through liquid-phase high-speed shearing, so as to realize the uniform dispersion of the aramid fiber in the fluororubber, and improve the processing flowability of the fluororubber and the dispersion uniformity of the aramid fiber;

[0025] Through the above-mentioned dual improvement mode of using the tannic acid as the surface modification aid of the aramid fiber and adding the dispersion aid, the tensile property, the compression permanent deformation, the heat-oxygen aging resistance and the oil resistance of the fluororubber are significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a microscope photo of the fluororubber aramid fiber composite material prepared in Example 1 in the present application;

[0027] Figure 2 is a microscope photo of the fluororubber aramid fiber composite material prepared in Comparative Example 2 in the present application. DETAILED DESCRIPTION

[0028] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments will be described clearly and completely below with reference to the drawings in the embodiments of the present application. The following embodiments are used to explain the present application but not to limit the scope of the present application.

[0029] The raw materials used in the examples and comparative examples in the present application are described below, but are not limited to the following raw materials:

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

[0031] 2,2-bis-(4-hydroxyphenyl) hexafluoropropane (AF), benzyltriphenylphosphonium chloride (BPP), Shandong Bojin New Material Co., Ltd.;

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

[0033] Silicon powder (model XRD-W98), micro-silicon powder (model XRD-SP90), Qingdao Xiruida New Material Technology Co., Ltd.;

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

[0035] Short-cut aramid fiber, length 3 mm, Yantai Taixingxing Material Technology Co., Ltd.;

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

[0037] Iron red, magnesium oxide, Qingdao Kelin New Material Technology Co., Ltd.

[0038] In some embodiments, the present application provides a preparation method of fluororubber aramid fiber composite material, comprising the following steps:

[0039] (1) Formulation raw material weighing: weighing each material according to the formulation;

[0040] (2) Aramid fiber modification and hybridization: preparing a tannic acid aqueous solution, adding aramid fiber for shearing and peeling, then adding a dispersion aid for further shearing and mixing, and after standing, layering, filtering and vacuum drying, a hybrid filler is obtained; Further, the shearing and peeling parameters include: stator-rotor high-speed homogenizer shearing and peeling, rotation speed 5000-10000 r / min, time 10-30 min; the shearing and mixing parameters include: stator-rotor high-speed homogenizer shearing and mixing, rotation speed 1000-6000 r / min, time 10-30 min;

[0041] (3) Internal mixing: the fluoroelastomer, functional filler, iron red, heat stabilizer-acid absorbent system are added to the internal mixer for first mixing, then the obtained hybrid filler is added for second mixing, finally 2,2-bis-(4-hydroxyphenyl) hexafluoropropane, benzyl triphenyl phosphonium chloride are added for third mixing, and the gum is discharged, thereby obtaining the first mixing rubber;

[0042] (4) Open mixing: the first mixing rubber is placed in the open mill for open mixing, after the mixing rubber is wrapped on the roll, the rubber is cut and the triangular bag is handled, and the sheet is obtained, thereby obtaining the second mixing rubber;

[0043] (5) Vulcanization: the second mixing rubber is cooled and placed for a predetermined time, then the two-stage vulcanization method is used for vulcanization, thereby obtaining the fluoroelastomer aramid fiber composite material; wherein the two-stage vulcanization method includes: the first stage vulcanization is carried out by using a flat vulcanizing machine, and the vulcanization is carried out at 170-180 o C, 10-20 MPa for 5-20 min; the second stage vulcanization is carried out by using an oven, and the vulcanization is carried out at 200-230 o C for 12-36 h.

[0044] As an embodiment of the present 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 the present application, in step (3), the first mixing conditions include: the first mixing temperature is 30-50 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 mixing and the third mixing are the same as the first mixing temperature and the first mixing speed, the second mixing time is 3-8 min, and the third mixing time is 3-5 min.

[0046] Further, in step (4), the temperature of the open mill is set to 25-40 o C; the rubber cutting and the triangular bag handling include sequentially performing 6-8 times of rubber cutting and 6-8 times of triangular bag operation.

[0047] Further, in step (5), the cooling and standing conditions before the vulcanization process include: the standing temperature is 25-40 o C, and the standing time is ≧6 h.

[0048] Referring to the fluoroelastomer aramid fiber composite material formula table in Table 1, the following examples are all prepared by using the above method unless otherwise specified.

[0049] The component allocation ratio of Comparative Examples 1-4 and Examples 1-3 is shown in Table 1, and the performance table of the obtained fluoroelastomer aramid fiber composite material is shown in Table 2 below.

[0050] Table 1 Fluoroelastomer aramid fiber composite material formula table

[0051]

[0052] Table 2 Performance of fluororubber aramid fiber composite material

[0053]

[0054] Specifically, the following specific description is made in combination with the fluororubber aramid fiber composite material formula in Table 1 (Comparative Examples 1-4 and Examples 1-3) and the performance of the fluororubber aramid fiber composite material in Table 2 (Comparative Examples 1-4 and Examples 1-3).

[0055] Comparative Example 1

[0056] Without adding aramid fiber and silicon powder, the prepared fluororubber material has poor physical and mechanical properties, and the stress, tensile strength, modulus, and tear strength values are low.

[0057] Comparative Example 2

[0058] Compared with Comparative Example 1, Comparative Example 2 adds aramid fiber, and the comprehensive performance of the fluororubber composite material decreases, which is due to the direct addition of aramid fiber, which is difficult to uniformly disperse and cannot form strong interfacial adhesion with fluororubber.

[0059] Comparative Example 3

[0060] Compared with Comparative Example 1, Comparative Example 3 adds silicon powder, and except for slightly increased tensile performance and tear performance, the compression permanent deformation, heat-resistant aging resistance, and oil resistance performance all slightly decrease, which is due to the weak reinforcing effect of silicon powder and weak interfacial molecular interaction with fluororubber. At high temperatures, the fluororubber molecular chains at the interface will slip, resulting in the above performance decrease.

[0061] Comparative Example 4

[0062] Compared with Comparative Example 2, Comparative Example 4 adds tannic acid modified aramid fiber, and the comprehensive performance of the fluororubber composite material has greatly improved, which is due to the tannic acid modification that can improve the dispersion uniformity of aramid fiber in fluororubber and the interfacial interaction with fluororubber.

[0063] Example 1

[0064] Compared with Comparative Example 4, Example 1 additionally adds 5 parts of silicon powder, and the comprehensive performance of the fluororubber composite material is further improved, which is due to the fact that silicon powder can improve the dispersion uniformity of aramid fiber in fluororubber. In addition, compared with Comparative Example 3, Example 1 additionally adds 3 parts of modified aramid fiber, and the comprehensive performance of the fluororubber composite material greatly improves, which again illustrates the effectiveness of the tannic acid modified aramid fiber.

[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 merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make some changes or modifications to the above-mentioned technical content with equivalent embodiments within the scope of the technical solutions of the present application. The embodiments in the above-mentioned embodiments can be further combined or replaced, as long as they do not deviate from the technical solutions of the present application. Any simple modification, equivalent change and modification made to the above-mentioned embodiments according to the technical essence of the present application are still within the scope of the present application.

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 tannic acid, and 3-10 parts of dispersing agent; The heat stabilizer-acid absorbent system includes magnesium oxide and / or calcium hydroxide, the functional filler is at least one of barium sulfate and calcium carbonate, and the dispersing aid is at least one of microsilica powder and silica powder.

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. A method for preparing the fluororubber-aramid fiber composite material as described in claim 1, 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.

5. The method for preparing the fluororubber-aramid fiber composite material according to claim 4, 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.

6. The method for preparing the fluororubber-aramid fiber composite material according to claim 4, 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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