Aramid pulp fiber / ethylene propylene diene monomer composite material and preparation method thereof

Abstract

The invention belongs to the technical field of composite materials, and particularly discloses an aramid pulp fiber / ethylene propylene diene monomer composite material and a preparation method thereof. The preparation method comprises the following steps: mixing raw ethylene-propylene-diene monomer rubber, carbon black, a flame retardant, a vulcanizing agent, an accelerant and modified aramid pulp, uniformly mixing to obtain a green sheet, and pressurizing and vulcanizing the green sheet on a flat vulcanizing machine to obtain the aramid pulp fiber / ethylene-propylene-diene monomer rubber composite material. The aramid pulp modified by the method disclosed by the invention has the characteristics of light microfiber entanglement degree and strong binding force with the ethylene propylene diene monomer, so that the aramid pulp fiber / ethylene propylene diene monomer composite material has better mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and specifically discloses an aramid pulp fiber / ethylene propylene diene monomer rubber composite material and a preparation method thereof. Background Art

[0002] Pulp-type aramid is a highly dispersed fibrillated aramid fiber product, which not only retains the excellent physical and mechanical properties of aramid fiber, such as high strength, high modulus, dimensional stability, etc., but also has rich hairy microfibers, huge specific surface area, and good toughness on the surface of aramid pulp. It will not break during the intense mixing process and will not reduce the aspect ratio of aramid pulp. Therefore, it has broad application prospects in the field of composite materials.

[0003] However, there are two problems that need to be solved before aramid pulp can be used in composite materials. First, aramid pulp has a regular chemical structure and is highly rigid. At the same time, the surface of aramid pulp does not have hydrophilic groups, which makes the surface activity of aramid pulp low. In order to better exert its excellent mechanical properties, it is necessary to improve the dispersibility of aramid pulp in composite materials. Generally, the surface properties of the fiber are improved by pretreatment and modification of the pulp surface, thereby improving the dispersion of the fiber in the pulp and the interface bonding of the composite material. The second problem is that there are a large number of microfibers in aramid pulp, and the microfibers are easily entangled, resulting in serious agglomeration of aramid pulp, which makes it poorly dispersed in the matrix resin of the composite material, affecting the performance of aramid pulp.

[0004] For this reason, a lot of research has been done in recent years to improve the reactivity of the aramid pulp surface, such as co-precipitation, white carbon black treatment, plasma treatment, surfactant treatment, etc. Different treatment methods can improve the interface performance between aramid and the composite matrix to a certain extent, but a single treatment method has its limitations and its effect is not ideal. How to prepare aramid pulp / polymer resin composite materials with good dispersibility and interface effect is still one of the problems that have not been well solved in the current application of aramid pulp.

[0005] Chinese patent CN117777499B discloses a method for preparing aramid pulp masterbatch and its application in oil-resistant rubber hoses, which also mentions that in the preparation of aramid pulp / nitrile rubber composite materials, microfiber disentanglement is first performed and then the aramid pulp is surface-modified with a coupling agent. However, the microfiber disentanglement method in this patented technology is to first treat the aramid pulp with plasma, and then use a precursor to in-situ grow nano-silicon dioxide on the surface of the aramid pulp fiber through a solution-gel method, thereby achieving the effect of microfiber disentanglement. However, this technology requires special plasma treatment equipment, and the process of in-situ growth of nano-silicon dioxide by a precursor in the solution-gel method is also relatively cumbersome, and the repeatability of each operation is poor.

[0006] Therefore, how to provide a simple and efficient method for disentanglement and surface modification of aramid pulp microfibers that does not require special equipment, has a short processing flow, and can be used on a large scale in industry remains a technical problem that needs to be urgently solved by those skilled in the art. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide an aramid pulp fiber / ethylene propylene diene monomer rubber composite material and a preparation method thereof in order to solve the problems existing in the prior art, which is a simple and efficient aramid pulp modification method and a preparation method of its ethylene propylene diene monomer rubber composite material.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] The first object of the present invention is to provide an aramid pulp fiber / ethylene propylene diene monomer rubber composite material, which is mainly obtained by mixing and vulcanizing the following raw materials, and the raw materials specifically include the following components, calculated by weight:

[0010] 100 parts of EPDM raw rubber, 10-30 parts of carbon black, 1-15 parts of flame retardant, 1-5 parts of vulcanizing agent, 1-5 parts of accelerator and 10-40 parts of modified aramid pulp.

[0011] Optionally, the preparation method of the modified aramid pulp is as follows:

[0012] (1) Mix 10-25 parts of aramid pulp, 50-80 parts of solvent and 10-20 parts of phosphoric acid for later use;

[0013] (2) Add 10-25 parts of microfiber isolation agent and 5-10 parts of interfacial compatibilizer to the system stirred and mixed in step (1), stir, let stand, dry, and then fluff up to obtain modified aramid pulp.

[0014] It should be noted that the purpose of stirring after adding the microfiber release agent is to allow the microfiber release agent to be fully adsorbed on the aramid microfibers to obtain disentangled aramid pulp, so that the aramid pulp is disentangled between the microfibers.

[0015] Furthermore, the standing time is 3-12 hours, the drying temperature is 70-100° C., and the drying time is 6-24 hours.

[0016] Furthermore, the fluffing treatment operation is: high-speed stirring at a rate of 1000-2000 r / min, and the treatment time is 10 minutes.

[0017] Furthermore, the solvent is one of anhydrous ethanol, acetone, methanol, or a mixture of several of them.

[0018] Furthermore, the microfiber isolation agent is inorganic nanoparticles or metal oxide nanoparticles; specifically, the microfiber isolation agent is one of nano-white carbon black, nano-silicon dioxide, nano-calcium carbonate, nano-titanium dioxide, nano-carbon black, nano-iron oxide, nano-zinc oxide, and nano-aluminum oxide.

[0019] Furthermore, the interfacial compatibilizer is one of KH570, pentaerythritol triacrylate and trimethylolpropane triacrylate.

[0020] It should be noted that in the modification process of the above-mentioned aramid pulp, each step has a synergistic relationship. First, phosphoric acid partially etches the microfiber surface of the aramid pulp to increase the roughness of the microfiber surface, making it easier to combine with the microfiber separator; then the microfiber separator is deposited on the microfiber surface of the aramid pulp to achieve the disentanglement of the microfibers of the aramid pulp; finally, the interfacial compatibilizer is added to help increase the interfacial bonding force between the aramid and the EPDM rubber matrix, and improve the dispersibility and compatibility of the pulp in the rubber.

[0021] The second object of the present invention is to provide a method for preparing the aramid pulp fiber / ethylene propylene diene monomer rubber composite material as described above, comprising the following steps:

[0022] According to mass fraction, 100 parts of EPDM raw rubber, 10-30 parts of carbon black, 1-15 parts of flame retardant, 1-5 parts of vulcanizer, 1-5 parts of accelerator and 10-40 parts of modified aramid pulp are mixed and kneaded to obtain a raw sheet after uniform mixing. The raw sheet is pressure-vulcanized on a flat vulcanizer to obtain an aramid pulp fiber / EPDM rubber composite material.

[0023] It should be further explained that the flame retardant, vulcanizing agent, accelerator and vulcanization conditions described in this case are all the formula and vulcanization conditions of the common EPDM rubber system. Specifically, the flame retardant can be trichloroethyl phosphate (TCEP) and tri(2-chloropropyl) phosphate (TCPP); the vulcanizing agent can be sulfur and dimethyl diphenylamine (DCP); the accelerator can be N-cyclohexyl-2-benzothiazole sulfonamide (CZ) and tetramethyl disulfide (TMTD); the vulcanization conditions vary according to the different vulcanizing agents and accelerators, and it is obvious to those skilled in the art to formulate different vulcanization process conditions according to different vulcanization formulas.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention adopts a two-step method to treat aramid pulp. First, the pulp microfibers are coated with microfiber isolation agent nanoparticles to reduce the interaction force between the microfibers, and the disentanglement between the aramid pulp microfibers can be effectively achieved. On this basis, an interfacial compatibilizer is further introduced to improve the interfacial bonding force between the pulp fiber and the EPDM rubber matrix, thereby improving the mechanical properties of the aramid pulp fiber / EPDM rubber composite material.

[0026] (2) At present, in the preparation process of aramid pulp fiber / EPDM rubber composite materials, only the fibers in the pulp are surface treated and then composited with the rubber matrix. Since the entanglement problem of pulp microfibers is not effectively solved, the effect of fiber surface treatment is not ideal, especially the entangled part of the fiber cannot be fully infiltrated by the interfacial compatibilizer, resulting in pulp agglomeration in the composite material. The present invention adopts a two-step method, the first step is to disentangle the aramid pulp microfibers, and the second step is to perform surface treatment, which can improve the effect of surface treatment and improve the interfacial bonding force between aramid pulp and EPDM rubber.

[0027] (3) The technology of the present invention is simple and efficient, does not require special equipment, has a short processing flow, and can be used on a large scale in industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0029] Figure 1 This is the SEM image of the composite material prepared in Example 1.

[0030] Figure 2 This is the SEM image of the composite material prepared in Example 3. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

[0033] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0034] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0035] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of the present application.

[0036] The embodiment of the invention discloses an aramid pulp fiber / ethylene propylene diene monomer rubber composite material and a preparation method thereof.

[0037] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0038] Example 1

[0039] 1. Add 1600 g of anhydrous ethanol, 300 g of aramid pulp and 300 g of phosphoric acid into a container respectively and stir for 4 hours to allow the aramid pulp to be fully soaked in the solution.

[0040] 2. Continue to add 300 grams of ultrafine nano-white carbon black and stir for 4 hours.

[0041] 3. Continue to add 100 g of trimethylolpropane triacrylate, stir to make it evenly dispersed, let it stand for 6 hours, filter to remove most of the solvent, then dry at 70°C for 18 hours, and use high-speed stirring at 1000-2000 r / min for fluffing treatment for 10 minutes to obtain dry modified aramid pulp.

[0042] 4. Add 100g of EPDM raw rubber, 20g of carbon black, 10g of flame retardant TCEP, 3g of sulfur, 1g of accelerator TMTD and 15g of modified aramid pulp into an open mill, mix them, mix them evenly, and then produce sheets, which are left for 24 hours.

[0043] 5. After the test piece is cut into a certain size with a mold, it is vulcanized on a flat vulcanizer at 160°C and 6MPa for 15 minutes to obtain an aramid pulp fiber / EPDM rubber composite material.

[0044] The aramid pulp fiber / EPDM rubber composite material in this embodiment has a tensile strength of 10 MPa and an elongation at break of 275%.

[0045] Attached Figure 1 This is a SEM spectrum of the cross section of the aramid pulp fiber / EPDM rubber composite material obtained in Example 1.

[0046] Example 2

[0047] In this embodiment, the content of modified pulp in the final composite material is different from that in embodiment 1, and thus the feed ratio of each raw material in step 4 is also different, and the rest is the same as that in embodiment 1.

[0048] The feeding ratio in step 1 is: 1000 g of EPDM raw rubber, 200 g of carbon black, 100 g of flame retardant TCPP, 30 g of sulfur, 10 g of accelerator TMTD and 250 g of modified aramid pulp are mixed on an open mixing mill.

[0049] The aramid pulp fiber / EPDM rubber composite material in this embodiment has a tensile strength of 7 MPa and an elongation at break of 217%.

[0050] Example 3

[0051] In this embodiment, only the microfiber isolation agent in step 2 is different from that in embodiment 1, resulting in different processing time and temperature in step 2, and the rest is the same as embodiment 1.

[0052] In this embodiment, step 2 is: continue to add 250 grams of nano titanium dioxide and stir for 3 hours.

[0053] The aramid pulp fiber / EPDM rubber composite material in this embodiment has a tensile strength of 9.3 MPa and an elongation at break of 307%.

[0054] Attached Figure 2 This is a SEM spectrum of the cross section of the aramid pulp fiber / EPDM rubber composite material obtained in Example 3.

[0055] Depend on Figure 1 and Figure 2It can be seen that under the conditions disclosed in Examples 1 and 3, the microfibers in the aramid pulp are straightened and dispersed in the composite matrix without obvious entanglement, which helps to improve the performance of the composite material.

[0056] The content of the present invention is not limited to the content of the above embodiments. The combination of one or more embodiments can also achieve the purpose of the present invention.

[0057] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the following comparative examples are used to further illustrate the technical features disclosed in the present invention, but they should not be construed as limiting the present invention. Other improvements made by those skilled in the art based on the above invention content without inventive work are also considered to fall within the scope of protection of the present invention.

[0058] Comparative Example 1

[0059] 1. Mix 100 g of EPDM raw rubber, 20 g of carbon black, 10 g of flame retardant TCEP, 3 g of sulfur and 1 g of accelerator TMTD on an open mill, mix them evenly, and then form sheets and leave them for 24 hours.

[0060] 2. After the test piece is cut into a certain size with a mold, it is vulcanized on a flat vulcanizer at 160°C and 6MPa pressure for 15 minutes to obtain pure EPDM rubber.

[0061] This comparative example is pure EPDM rubber without any aramid pulp added. The obtained rubber has a tensile strength of 16 MPa and an elongation at break of 412%.

[0062] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An aramid pulp fiber / ethylene propylene diene monomer rubber composite material, characterized in that: The material is mainly obtained by mixing and vulcanizing the following raw materials, and the raw materials specifically include the following components, calculated by weight: 100 parts of EPDM raw rubber, 10-30 parts of carbon black, 1-15 parts of flame retardant, 1-5 parts of vulcanizing agent, 1-5 parts of accelerator and 10-40 parts of modified aramid pulp.

2. The aramid pulp fiber / EPDM rubber composite material according to claim 1, characterized in that: The preparation method of the modified aramid pulp is as follows: (1) Mix 10-25 parts of aramid pulp, 50-80 parts of solvent and 10-20 parts of phosphoric acid for later use; (2) Add 10-25 parts of microfiber isolation agent and 5-10 parts of interfacial compatibilizer to the system stirred and mixed in step (1), stir, let stand, dry, and then fluff up to obtain modified aramid pulp.

3. The aramid pulp fiber / EPDM rubber composite material according to claim 2, characterized in that: The standing time is 3-12 hours, the drying temperature is 70-100℃, and the drying time is 6-24 hours.

4. The aramid pulp fiber / EPDM rubber composite material according to claim 2, characterized in that: The fluffing treatment operation is: high-speed stirring at a rate of 1000-2000 r / min, and the treatment time is 10 minutes.

5. The aramid pulp fiber / EPDM rubber composite material according to any one of claims 2 to 4, characterized in that: The solvent is one of anhydrous ethanol, acetone, and methanol, or a mixture of several of them.

6. The aramid pulp fiber / EPDM rubber composite material according to any one of claims 2 to 4, characterized in that: The microfiber separator is inorganic nanoparticles or metal oxide nanoparticles; specifically, the microfiber separator is one of nano white carbon black, nano silicon dioxide, nano calcium carbonate, nano titanium dioxide, nano carbon black, nano iron oxide, nano zinc oxide, and nano aluminum oxide.

7. The aramid pulp fiber / EPDM rubber composite material according to any one of claims 2 to 4, characterized in that: The interfacial compatibilizer is one of KH570, pentaerythritol triacrylate and trimethylolpropane triacrylate.

8. A method for preparing the aramid pulp fiber / EPDM rubber composite material as claimed in claim 1, characterized in that: The following steps are involved: According to the weight proportions as claimed in claim 1, EPDM raw rubber, carbon black, flame retardant, vulcanizing agent, accelerator and modified aramid pulp are weighed respectively, mixed and kneaded, and a raw sheet is obtained after the mixing is uniform; the raw sheet is pressurized and vulcanized to obtain the aramid pulp fiber / EPDM composite material.

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