Aramid pulp, aramid pulp composite polyolefin elastomer master batch as well as preparation method and application of aramid pulp composite polyolefin elastomer master batch

Abstract

The invention belongs to the field of aramid fiber rubber composite materials, and particularly relates to aramid fiber pulp, an aramid fiber pulp composite polyolefin elastomer master batch and a preparation method and application of the aramid fiber pulp composite polyolefin elastomer master batch. The aramid pulp comprises a first modifier and a second modifier. The aramid pulp and the aramid pulp composite polyolefin elastomer master batch provided by the invention solve the application problem of the aramid pulp in rubber. According to the invention, the process steps and formula of the aramid pulp master batch are optimized, the introduction of chemical reagents with negative influence is reduced, the comprehensive performance of the rubber composite material is improved, the production efficiency is improved, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aramid rubber composites, and particularly relates to aramid pulp, aramid pulp composite polyolefin elastomer masterbatch, and a preparation method and application thereof. BACKGROUND

[0002] Aramid pulp (AP) is a highly fibrillated product of para-aramid filaments, which not only has the chemical resistance and temperature resistance of aramid filaments, but also has good adhesion and friction resistance due to its special fluffy micro-fiber structure. Therefore, AP is an excellent rubber reinforcing material that can improve the tear resistance of rubber products. However, due to the inertness of the aramid fiber interface and the micro-entangled structure of AP, it cannot be uniformly dispersed in rubber, which greatly restricts the application and promotion of AP in rubber-based composites.

[0003] In order to solve the problem of difficult dispersion of AP, the prior art adopts two schemes, namely isolation method and emulsion method.

[0004] The isolation method, such as patents CN112940305B and CN110885461B, is a blending of AP with various chemical reagents, such as blending AP with modifiers, coupling agents, dispersion solvents and separation agents, forming a chemical grafting modification on the surface of AP, so that it has a certain interfacial strength and dispersibility, and then blending with rubber or resin for reinforcement. This method not only has many steps, but also introduces many chemicals. With the increase of the amount of calcium carbonate, talc, carbon black or white carbon black commonly used as separation agents, filler-filler interactions (Payne effect), hysteresis loss and other effects will eventually affect the overall performance of the rubber product. In addition, the use of multiple reagents requires high precision and efficiency of the processing equipment. Therefore, although this scheme solves some technical problems to some extent, it has low industrialization and commercialization value.

[0005] The emulsion method is a commercialized scheme, such as the aramid pulp masterbatch product of DuPont Company, Kevlar EE, which is a pre-dispersion of aramid pulp and rubber emulsion. This scheme avoids the introduction of a large amount of separation agent, and can produce different AP latex pre-dispersions according to the type of the final rubber compound, including AP-NR, AP-NBR and other types of products. The problem of this technical scheme is that the processing difficulty is higher. Since AP needs to be dispersed with rubber latex to a certain degree after blending with emulsion, the solvent needs to be removed and recovered, so the process control and equipment have high requirements. Therefore, the production capacity of this technical scheme is low, and the cost is high.

[0006] Therefore, there is still a need in the art for an AP with good dispersibility and an AP rubber composite material with good dispersibility of AP, simple preparation method and suitable for industrial application. SUMMARY

[0007] The present application aims at the above-mentioned problems existing in the prior art, and provides an aramid pulp, an aramid pulp composite polyolefin elastomer masterbatch, and a preparation method and application thereof. The present application modifies the aramid pulp by combining a first modifier and a second modifier, thereby improving the dispersibility of the aramid pulp in the polyolefin elastomer. The present application prepares the aramid pulp composite polyolefin elastomer masterbatch by using the aramid pulp, the polyolefin elastomer and the masterbatch modifier, thereby improving the dispersibility of the masterbatch in the rubber material, and further improving the wear resistance and tear resistance of the aramid rubber composite material.

[0008] Specifically, the present application provides an aramid pulp, which comprises a first modifier and a second modifier. The first modifier is a glycidyl ether compound, and the second modifier is an amino-containing siloxane compound.

[0009] In one or more embodiments, the first modifier is selected from one or more of sorbitol glycidyl ether, glycerol triglycidyl ether, pentaerythritol tetraglycidyl ether, diglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether and lignin oil alcohol soluble phenolic polyglycidyl ether; preferably, the first modifier is sorbitol glycidyl ether; preferably, the viscosity of the sorbitol glycidyl ether is 5000±500 mPa·s, and the epoxy equivalent weight is 173±10 g / eq.

[0010] In one or more embodiments, the second modifier is selected from one or more of amino-modified polysiloxane, N-(n-butyl)-3-aminopropyltrimethoxysilane, bis[3-(triethoxysilyl)propyl]amine, 3-aminopropyltriethylsiloxane and triamino-functionalized propyltrimethoxysilane; preferably, the second modifier is amino-modified polysiloxane; preferably, the viscosity of the amino-modified polysiloxane is 5±1 mPa·s, the active silane content is 40±10%, and the amino content is 10%-22%.

[0011] In one or more embodiments, the percentage content of the first modifier and the second modifier in the total mass of the aramid pulp is 1wt%-5.5wt%, preferably 4wt%-5wt%.

[0012] In one or more embodiments, the mass ratio of the second modifier to the first modifier is (5-15):100, preferably (9-11):100.

[0013] In one or more embodiments, the aramid pulp is a para-aramid pulp.

[0014] In one or more embodiments, the aramid pulp has a fiber length of 0.8-1.3mm.

[0015] In one or more embodiments, the aramid pulp has a specific surface area of 6.50-11.50g / m 2 .

[0016] In one or more embodiments, the aramid pulp has a Canadian freeness of 340-460mL;

[0017] The present application also provides a method for preparing the aramid pulp according to any one of the embodiments, the method comprising the following steps:

[0018] (1) providing short-cut fibers;

[0019] (2) dispersing the short-cut fibers in a modified solution for grinding, drying and opening the ground wet pulp to obtain the aramid pulp;

[0020] The modified solution is an aqueous solution containing the first modifier and the second modifier.

[0021] In one or more embodiments, the short-cut fibers are cut from aramid filaments.

[0022] In one or more embodiments, the short-cut fibers have a length of 4-10mm.

[0023] In one or more embodiments, the content of the first modifier in the modified solution is 10wt%-20wt%, preferably 15±1wt%.

[0024] In one or more embodiments, the mass ratio of the second modifier to the first modifier in the modified solution is (5-15):100, preferably (9-11):100.

[0025] In one or more embodiments, the mass ratio of the short-cut fibers to the modified solution is 1:(10-15).

[0026] The present application also provides an aramid pulp composite polyolefin elastomer masterbatch, which comprises the aramid pulp according to any one of the embodiments, a polyolefin elastomer and a masterbatch modifier.

[0027] In one or more embodiments, the polyolefin elastomer is an ethylene octene copolymer.

[0028] In one or more embodiments, the polyolefin elastomer has a density of 0.85-0.88g / cm 3 .

[0029] In one or more embodiments, the polyolefin elastomer has a crystallinity of 19-21%.

[0030] In one or more embodiments, the polyolefin elastomer has a Shore A hardness of 68-75.

[0031] In one or more embodiments, the polyolefin elastomer has a melt flow rate of 5-20 g / 10 min @ 190°C.

[0032] In one or more embodiments, the polyolefin elastomer has a tensile strength of 3.3-6.9 MPa.

[0033] In one or more embodiments, the polyolefin elastomer has a flexural modulus of 11.8-13.6 MPa.

[0034] In one or more embodiments, the masterbatch modifier is selected from one or both of a first modifier and a second modifier, the first modifier being a glycidyl ether compound, and the second modifier being an amino-containing siloxane compound.

[0035] In one or more embodiments, the first modifier is selected from one or more of sorbitol glycidyl ether, glycerol triglycidyl ether, pentaerythritol tetraglycidyl ether, diglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, and lignin oil soluble phenol formaldehyde polyglycidyl ether.

[0036] In one or more embodiments, the second modifier is selected from one or more of an amino-modified polysiloxane, N-(n-butyl)-3-aminopropyltrimethoxysilane, bis[3-(triethoxysilyl)propyl]amine, 3-aminopropyltriethylsiloxane, and triamino-functionalized propyltrimethoxysilane.

[0037] In one or more embodiments, the masterbatch modifier is an amino-modified polysiloxane; preferably, the amino-modified polysiloxane has a viscosity of 5 ± 1 mPa·s, an active silane content of 40 ± 10%, and an amino content of 10-22%.

[0038] In one or more embodiments, in the aramid pulp composite polyolefin elastomer masterbatch, the aramid pulp has a mass of 10-60%, preferably 20-50%, more preferably 30-40% of the total mass of the aramid pulp and the polyolefin elastomer.

[0039] In one or more embodiments, in the aramid pulp composite polyolefin elastomer masterbatch, the masterbatch modifier has a mass of 30-50%, preferably 40 ± 5% of the mass of the aramid pulp.

[0040] The present application also provides a method for preparing the aramid pulp composite polyolefin elastomer masterbatch according to any one of the embodiments, which comprises: feeding the mixture of the aramid pulp and the masterbatch modifier into a screw extruder, feeding the polyolefin elastomer into the screw extruder, and blending and extruding the mixture and the polyolefin elastomer in the screw extruder to obtain the aramid pulp composite polyolefin elastomer masterbatch.

[0041] In one or more embodiments, the screw extruder is a twin-screw extruder.

[0042] In one or more embodiments, the polyolefin elastomer is fed from the main feeding port.

[0043] In one or more embodiments, the mixture is fed from the side feeding port.

[0044] In one or more embodiments, the feeding temperature of the polyolefin elastomer is 160-180°C, preferably 170±5°C.

[0045] In one or more embodiments, the feeding of the mixture is performed using a loss-in-weight feeder.

[0046] In one or more embodiments, the processing temperature of the screw extruder is set as follows: the temperature of the feeding zone of the main feeding port is 110-130°C, the temperature of the melt compression zone of the main feeding port is 150-160°C, the temperature of the melt conveying zone is 160-170°C; the temperature of the side feeding port is 170±5°C; the temperature of the dispersion mixing section is 165-168°C; the temperature of the exhaust section and the die is 170±5°C; and the cooling section is cooled using water at 7-14°C, preferably 7-10°C.

[0047] In one or more embodiments, the screw rotation speed of the screw extruder is 100-400 rpm, preferably 100-300 rpm, and further preferably 100-200 rpm.

[0048] The present application also provides an aramid rubber composite material comprising the aramid pulp composite polyolefin elastomer masterbatch according to any one of the embodiments and a rubber material.

[0049] In one or more embodiments, the rubber material comprises natural rubber.

[0050] In one or more embodiments, the mass ratio of the aramid pulp composite polyolefin elastomer masterbatch to the rubber material is (0.1-10):100, preferably (1-3):100.

[0051] The application provides a preparation method of high-efficiency aramid pulp composite polyolefin elastomer master batch, and is applied to rubber composite friction material. The polyolefin elastomer (POE) is used as AP into the carrier of the rubber and the modifier of the rubber matrix, is applied to natural rubber or synthetic rubber, solves the problem that the AP is not easy to disperse, provides a large-scale production path, improves the wear resistance and tear resistance of the rubber composite material, and reduces the friction heat. In the application, the wear resistance and tear resistance of the rubber composite material are improved, which means that the dispersibility of the aramid pulp and the master batch is improved. DETAILED DESCRIPTION

[0052] To enable those skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in this text. Unless otherwise specified, all technical and scientific words used in this text are the usual meanings understood by those skilled in the art for the present application, and in the event of a conflict, the definition in this specification shall prevail.

[0053] Theories or mechanisms described and disclosed herein, whether correct or not, should not be considered limiting the scope of the present application, i.e., the present application can be practiced without relying on any particular theory or mechanism.

[0054] In this text, "contains", "includes", "comprises" and similar phrases cover the meaning of "consists essentially of" and "consists of", for example, when this text discloses "A contains B and C", "A consists essentially of B and C" and "A consists of B and C" should be considered to have been disclosed in this text.

[0055] In this text, all features defined in the form of numerical range or percentage range, such as numerical value, quantity, content and concentration, are for the sake of brevity and convenience. Therefore, the description of numerical range or percentage range should be considered to have covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0056] In this text, unless otherwise specified, percentage refers to mass percentage, and ratio refers to mass ratio.

[0057] In this text, the sum of the percentage content of each component of the composition is 100%.

[0058] In this text, when describing embodiments or examples, it should be understood that they are not intended to limit the present application to these embodiments or examples. On the contrary, all alternatives, modifications and equivalents of the methods and materials described in the present application can be covered within the scope of the present application.

[0059] Herein, all possible combinations of the various technical features in the various embodiments or examples are not described in order to simplify the description. Therefore, as long as there is no contradiction in the combination of the technical features, the technical features in the various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered as the scope of the present disclosure.

[0060] The aramid pulp of the present application contains a first modifier and a second modifier.

[0061] In the present application, the first modifier is a glycidyl ether compound. In the present application, as the first modifier, one or more of sorbitol glycidyl ether, glycerol triglycidyl ether, pentaerythritol tetraglycidyl ether, diglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, and wood tar alcohol-soluble phenol-formaldehyde polyglycidyl ether are preferred. In some particularly preferred embodiments, the first modifier is sorbitol glycidyl ether. Selecting the above compounds as the first modifier can better exert a synergistic effect with the second modifier in improving the dispersibility of aramid pulp.

[0062] In the present application, the second modifier is an amino-containing siloxane compound. In the present application, the amino group includes -NH2 and -NH-, and the siloxane compound refers to a compound containing the structure -Si-O-C-. In the present application, as the second modifier, one or more of amino-modified polysiloxane, N-(n-butyl)-3-aminopropyltrimethoxysilane, bis[3-(triethoxysilyl)propyl]amine, 3-aminopropyltriethylsiloxane, and triamino-functionalized propyltrimethoxysilane are preferred. In some particularly preferred embodiments, the second modifier is amino-modified polysiloxane. Selecting the above compounds as the second modifier can better exert a synergistic effect with the first modifier in improving the dispersibility of aramid pulp.

[0063] In the present application, the combination of the small-molecule glycidyl ether with good water solubility and the amino-containing siloxane has good modification effect, and the synergistic effect of the two increases a large number of hydrophilic active groups for aramid pulp.

[0064] In the present application, the first modifier and the second modifier endow the aramid pulp with specific functional groups (such as epoxy groups, siloxane bonds, and amino groups). Compared with using the first modifier alone or using the second modifier alone, the present application uses the first modifier and the second modifier in combination to modify the aramid pulp, which can make the aramid pulp have better dispersibility in the polyolefin elastomer, and make the aramid pulp composite polyolefin elastomer masterbatch prepared subsequently have better dispersibility in the rubber material.

[0065] The chemical structure of aramid pulp without modification agent treatment is consistent with the fiber filament, and the molecular chain has amide groups, which has a certain grafting basis. The steric effect of the rigid benzene ring in aramid pulp and its highly crystalline state result in a low surface energy of aramid pulp, which affects its dispersibility. Moreover, the change in the microstate of aramid pulp causes the mutual entanglement and adhesion between microfibers, which further exacerbates the difficulty of dispersion.

[0066] The main component of the first modification agent is glycidyl ether, and its active factor is an epoxy group. The epoxy group can react with the amide bond in aramid pulp under acidic and basic conditions, thereby increasing the surface energy of aramid pulp, and further improving the dispersibility of aramid pulp in polyolefin elastomer.

[0067] The second modification agent contains amino and siloxane bonds. The amino group has good hydrophilicity, and the second modification agent containing amino groups can act as an interfacial agent between aramid pulp and polyolefin elastomer, thereby improving the bonding force between aramid pulp and polyolefin elastomer. The amino group can also form a chemical bond with the hydroxyl group in glycidyl ether, thereby further improving the bonding force between aramid pulp and polyolefin elastomer. Therefore, the second modification agent can cooperate with the first modification agent to further improve the dispersibility of aramid pulp in polyolefin elastomer. The siloxane bond is a typical chemical bond of silane system, and the second modification agent containing siloxane bond can ensure the stability of the chemical state of aramid pulp at high temperature.

[0068] Therefore, the combined action of the first modification agent and the second modification agent improves the dispersibility of aramid pulp in polyolefin elastomer.

[0069] In addition, the presence of the first modification agent and the second modification agent between aramid pulp and polyolefin elastomer increases the force of chemical bonds and intermolecular hydrogen bonds. On this basis, the grading shear action of the twin screw makes the dispersibility of aramid pulp in polyolefin elastomer better. Moreover, the first modification agent and the second modification agent can be highly dispersed in water, and the presence of aqueous solution reduces the heat accumulation in the shear of the twin screw, thereby maintaining the uniformity of the dispersion of aramid pulp in polyolefin elastomer.

[0070] In a preferred embodiment, the total mass percentage of the first modification agent and the second modification agent in the aramid pulp of the present application is 1wt%-5.5wt%, preferably 4wt%-5wt%, for example 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%.

[0071] Controlling the total mass percentage of the first modification agent and the second modification agent in aramid pulp within the aforementioned range is beneficial to the synergistic effect of the first modification agent and the second modification agent in improving the dispersibility of aramid pulp in polyolefin elastomer.

[0072] In the present application, the mass ratio of the second modifier to the first modifier can be (5-15):100, preferably (9-11):100, for example 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 11:100, 12:100, 13:100, 14:100, 15:100.

[0073] Controlling the mass ratio of the first modifier and the second modifier in the aramid pulp within the aforementioned range is conducive to exerting the effect of the first modifier and the second modifier in synergistically improving the dispersibility of the aramid pulp in the polyolefin elastomer.

[0074] In some preferred embodiments, the aramid pulp can contain sorbitol glycidyl ether and amino-modified polysiloxane.

[0075] In the present application, the aramid pulp can be para-aramid pulp.

[0076] In the present application, the fiber length of the aramid pulp can be 0.8-1.3 mm, for example 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm.

[0077] In the present application, the specific surface area of the aramid pulp can be 6.50-11.50 g / m 2 , for example 6.50 g / m 2 , 7.00 g / m 2 , 7.50 g / m 2 , 8.00 g / m 2 , 8.50 g / m 2 , 9.00 g / m 2 , 9.50 g / m 2 , 10.00 g / m 2 , 10.50 g / m 2 , 11.00 g / m 2 , 11.50 g / m 2 .

[0078] In the present application, the Canadian freeness of the aramid pulp can be 340-460 mL, for example 340 mL, 360 mL, 380 mL, 400 mL, 420 mL, 440 mL, 460 mL.

[0079] In some preferred embodiments, the viscosity of the sorbitol glycidyl ether can be 5000±500 mPa·s, for example 4500 mPa·s, 4600 mPa·s, 4800 mPa·s, 5000 mPa·s, 5200 mPa·s, 5500 mPa·s.

[0080] In some preferred embodiments, the epoxy equivalent weight of the sorbitol glycidyl ether can be 173 ± 10 g / eq., such as 163 g / eq., 165 g / eq., 170 g / eq., 173 g / eq., 175 g / eq., 180 g / eq., 183 g / eq.

[0081] The viscosity and the epoxy equivalent weight of the first modifier are preferably within the aforementioned ranges. The viscosity and the epoxy equivalent weight of the first modifier can affect the dispersibility of the aramid pulp in the polyolefin elastomer. For example, when the viscosity and the epoxy equivalent weight of the sorbitol glycidyl ether are not within the aforementioned ranges, the mixed system of the aramid pulp and the polyolefin elastomer does not have the twin-screw shearing processing ability.

[0082] In some preferred embodiments, the viscosity of the amino-modified polysiloxane can be 5 ± 1 mPa·s, such as 4 mPa·s, 4.5 mPa·s, 5 mPa·s, 5.5 mPa·s, 6 mPa·s.

[0083] In some preferred embodiments, the active silane content of the amino-modified polysiloxane can be 40 ± 10%, such as 30%, 35%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%.

[0084] In some preferred embodiments, the amino content of the amino-modified polysiloxane can be 10%-22%, such as 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%.

[0085] The selection of the second modifier of the present application can cooperate with the first modifier to improve the dispersibility of the aramid pulp in the polyolefin elastomer. The viscosity, the amino content, and the active silane content of the second modifier are preferably within the aforementioned ranges. The viscosity, the amino content, and the active silane content of the second modifier can affect the dispersibility of the aramid pulp in the polyolefin elastomer. For example, when the viscosity, the amino content, and the active silane content of the amino-modified polysiloxane are not within the aforementioned ranges, the mixed system of the aramid pulp and the polyolefin elastomer does not have the twin-screw shearing processing ability.

[0086] The present application also provides a method for preparing the aramid pulp as described above, comprising the following steps:

[0087] (1) providing short-cut fibers;

[0088] (2) dispersing the short-cut fibers in a modified solution for grinding, drying, and opening the ground wet pulp to obtain the aramid pulp.

[0089] In the present application, the modified solution can be an aqueous solution containing the first modifier and the second modifier.

[0090] In the present application, the short-cut fibers can be cut from aramid filaments.

[0091] In the present application, the length of the short-cut fibers can be 4-10mm, for example 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm.

[0092] In the modified solution of the present application, the content of the first modifier can be 10wt%-20wt%, preferably 15±1wt%, for example 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%.

[0093] In the modified solution of the present application, the mass ratio of the second modifier to the first modifier can be (5-15):100, preferably (9-11):100, for example 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 11:100, 12:100, 13:100, 14:100, 15:100.

[0094] In the present application, the addition amount of the first modifier and the second modifier in the modified solution is controlled within the aforementioned range, which can make the aramid pulp contain an appropriate amount of specific functional groups (such as epoxy group, silicon-oxygen bond, amino group), and endow the aramid pulp with better dispersibility.

[0095] In the present application, the mass ratio of the short-cut fibers to the modified solution can be 1:(10-15), for example 1:10, 1:11, 1:12, 1:13, 1:14, 1:15.

[0096] The present application also provides an aramid pulp composite polyolefin elastomer masterbatch. The aramid pulp composite polyolefin elastomer masterbatch of the present application comprises the aramid pulp, the polyolefin elastomer and the masterbatch modifier described above.

[0097] Compared with using other resins as masterbatch carrier resins, the use of polyolefin elastomer as the masterbatch carrier resin of the aramid pulp of the present application for rubber materials can improve the wear resistance and tear resistance of aramid rubber composite materials. This is because the aramid pulp of the present application has good dispersibility in polyolefin elastomer, and the aramid pulp composite polyolefin elastomer masterbatch of the present application has good dispersibility in rubber materials.

[0098] The aramid pulp of the present application has a high specific surface area and all the physical and chemical properties of aramid filaments. The dispersion problem of aramid pulp in polyolefin elastomer is solved, that is, the aramid pulp can play the advantages of good size stability and high strength modulus in rubber materials, and further improve the wear resistance and tear resistance. At the same time, the present application can avoid the components that may cause negative effects in the existing master batch scheme, such as silica release agent, which will cause heat generation in the later vulcanization process.

[0099] In the present application, the polyolefin elastomer can be ethylene octene copolymer.

[0100] In some embodiments, the polyolefin elastomer can be an elastomeric material synthesized from ethylene and 1-octene. The polyolefin elastomer has a soft rubber phase and a hard plastic phase. Among them, the octene segment can provide high elasticity; the ethylene segment can act as a physical crosslinking point at high temperature, providing strength.

[0101] In the present application, the density of the polyolefin elastomer can be 0.85-0.88g / cm 3 , for example 0.85g / cm 3 , 0.86g / cm 3 , 0.87g / cm 3 , 0.88g / cm 3 .

[0102] In the present application, the crystallinity of the polyolefin elastomer can be 19%-21%, for example 19%, 20%, 21%.

[0103] In the present application, the Shore A hardness of the polyolefin elastomer can be 68-75, for example 68, 69, 70, 71, 72, 73, 74, 75.

[0104] In the present application, the melt flow rate of the polyolefin elastomer can be 5-20g / 10min@190℃, for example 5g / 10min@190℃, 8g / 10min@190℃, 10g / 10min@190℃, 12g / 10min@190℃, 14g / 10min@190℃, 16g / 10min@190℃, 18g / 10min@190℃, 20g / 10min@190℃.

[0105] In the present application, the tensile strength of the polyolefin elastomer can be 3.3-6.9MPa, for example 3.3MPa, 3.6MPa, 3.9MPa, 4.3MPa, 4.6MPa, 4.9MPa, 5.3MPa, 5.6MPa, 5.9MPa, 6.3MPa, 6.6MPa, 6.9MPa.

[0106] In the present invention, the polyolefin elastomer can have a flexural modulus of 11.8-13.6 MPa, such as 11.8 MPa, 12.0 MPa, 12.2 MPa, 12.4 MPa, 12.6 MPa, 12.8 MPa, 13.0 MPa, 13.2 MPa, 13.4 MPa, 13.6 MPa.

[0107] In the present invention, the masterbatch modifier can be selected from one or both of a first modifier and a second modifier. The first modifier is a glycidyl ether compound, and the second modifier is an amino-containing siloxane compound.

[0108] In some preferred embodiments, the first modifier as the masterbatch modifier can be selected from one or more of sorbitol glycidyl ether, glycerol triglycidyl ether, pentaerythritol tetraglycidyl ether, diglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, and lignin oil soluble phenol formaldehyde polyglycidyl ether.

[0109] In some preferred embodiments, the second modifier as the masterbatch modifier can be selected from one or more of amino-modified polysiloxane, N-(n-butyl)-3-aminopropyltrimethoxysilane, bis[3-(triethoxysilyl)propyl]amine, 3-aminopropyltriethylsiloxane, and triamino-functionalized propyltrimethoxysilane.

[0110] The present invention adds a masterbatch modifier containing a specific functional group (such as one or more of an epoxy group, a siloxane bond, and an amino group) to the aramid pulp composite polyolefin elastomer masterbatch, which can improve the dispersibility of aramid pulp in the masterbatch, and further improve the wear resistance and tear resistance of aramid rubber composite materials.

[0111] In some particularly preferred embodiments, the masterbatch modifier is an amino-modified polysiloxane. This is particularly advantageous for improving the dispersibility of aramid pulp in the masterbatch, and further improving the wear resistance and tear resistance of aramid rubber composite materials.

[0112] The masterbatch modifier can be selected from one or both of the first modifier and the second modifier, so that the masterbatch modifier contains a specific functional group (such as one or more of an epoxy group, a siloxane bond, and an amino group). Among them, the epoxy group is the active factor of glycidyl ether, which can react with the amide bond in aramid pulp under acidic and alkaline conditions, thereby increasing the surface energy of the aramid pulp and improving the dispersibility of the aramid pulp in the masterbatch. The amino group has good hydrophilicity, and the masterbatch modifier containing the amino group can act as an interfacial agent between the aramid pulp and the polyolefin elastomer, thereby improving the bonding force between the aramid pulp and the polyolefin elastomer; the amino group can also form a chemical bond with the hydroxyl group in the glycidyl ether in the modified aramid pulp, thereby further improving the bonding force between the aramid pulp and the polyolefin elastomer and the dispersibility of the aramid pulp in the masterbatch. The siloxane bond is a typical chemical bond of the silane system, and the masterbatch modifier containing the siloxane bond can ensure the chemical stability of the aramid pulp at high temperatures. Therefore, the masterbatch modifier improves the dispersibility of the aramid pulp in the masterbatch.

[0113] In addition, the presence of the masterbatch modifier increases the force of the chemical bond and the intermolecular hydrogen bond between the aramid pulp and the polyolefin elastomer. On this basis, the grading shearing action of the twin screw can further improve the dispersibility of the aramid pulp in the masterbatch. Moreover, the masterbatch modifier can be highly dispersed in water, and the presence of the aqueous solution reduces the heat accumulation in the shearing of the twin screw, thereby maintaining the uniformity of the dispersion of the aramid pulp in the polyolefin elastomer.

[0114] In some preferred embodiments, the masterbatch modifier can be an amino-modified polysiloxane. The present application finds that the amino-modified polysiloxane containing a siloxane bond and an amino group as a masterbatch modifier has a particularly good effect on improving the dispersibility of aramid pulp and enhancing the wear resistance and tear resistance of aramid rubber composites.

[0115] In some preferred embodiments, the masterbatch modifier can be an amino-modified polysiloxane, and the amino-modified polysiloxane can form good bonding with the aramid pulp, the polyolefin elastomer, and the first modifier. After the addition of the masterbatch modifier, the amino-modified polysiloxane with good hydrophilicity can act as an interfacial agent between the aramid pulp and the polyolefin elastomer, thereby improving the bonding force between the aramid pulp and the polyolefin elastomer; the amino-modified polysiloxane can also form a chemical bond with the hydroxyl group in the glycidyl ether in the first modifier in the modified aramid pulp, thereby further improving the bonding force between the aramid pulp and the polyolefin elastomer and further improving the dispersibility of the aramid pulp in the masterbatch. The amino-modified polysiloxane can also ensure the chemical stability of the aramid pulp at high temperatures. Therefore, the amino-modified polysiloxane as a masterbatch modifier improves the dispersibility of the aramid pulp.

[0116] In some preferred embodiments, the viscosity of the amino-modified polysiloxane can be 5±1 mPa·s, for example 4 mPa·s, 4.5 mPa·s, 5 mPa·s, 6 mPa·s, the active silane content can be 40±10%, for example 30%, 35%, 40%, 45%, 50%, and the amino content can be 10%-22%, for example 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%.

[0117] In the aramid pulp composite polyolefin elastomer masterbatch of the present application, the mass of aramid pulp can be 10%-60% of the total mass of aramid pulp and the polyolefin elastomer, preferably 20%-50%, more preferably 30%-40%, for example 10%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%.

[0118] In the present application, controlling the content of aramid pulp in the aramid pulp composite polyolefin elastomer masterbatch within the above range can make the mixture of aramid pulp and polyolefin elastomer added in the twin-screw extruder have the required flowability in the process of melt shearing, mixing and conveying. If the content of aramid pulp in the masterbatch is too high, exceeding the maximum proportion in the above range, the flowability of the mixture of aramid pulp and polyolefin elastomer will be abnormal, the process difficulty of preparing the masterbatch will increase, and the performance of the prepared rubber product will be abnormal. If the content of aramid pulp in the masterbatch is too low, below the minimum proportion in the above range, the cost of preparing the masterbatch will be too high, and it will not be economical.

[0119] In the aramid pulp composite polyolefin elastomer masterbatch of the present application, the mass of the masterbatch modifier can be 30%-50% of the mass of aramid pulp, preferably 40±5%, for example 30%, 35%, 40%, 45%, 50%.

[0120] In the present application, controlling the amount of masterbatch modifier within the above range can make the aramid pulp composite polyolefin elastomer masterbatch have a suitable specific functional group, thereby improving the dispersibility of the masterbatch in rubber materials and improving the wear resistance and tear resistance of aramid rubber composite materials.

[0121] The present application also provides a method for preparing the above aramid pulp composite polyolefin elastomer masterbatch, which comprises: adding a mixture of aramid pulp and masterbatch modifier into a screw extruder, adding polyolefin elastomer into the screw extruder, and blending and extruding the mixture and the polyolefin elastomer in the screw extruder to obtain the aramid pulp composite polyolefin elastomer masterbatch. The screw extruder is preferably a twin-screw extruder.

[0122] In the present application, aramid pulp and polyolefin elastomer (POE) can be mixed uniformly by a twin-screw extruder, POE pellets can be added from the main feeding port, and aramid pulp can be added from the side feeding port by a loss-in-weight feeder in stages.

[0123] In the present application, the feeding temperature of POE can be 160-180℃, for example, 160℃, 165℃, 170℃, 175℃, 180℃, preferably 170℃, to ensure that POE has been completely melted and homogenized before the side feeding port.

[0124] In the present application, the setting of the blending processing temperature of aramid pulp and polyolefin elastomer POE, the setting temperature of the feeding area of the main feeding port can be 110-130℃, for example 110℃, 115℃, 120℃, 125℃, 130℃, to prevent POE from softening and sticking too early.

[0125] In the present application, the setting temperature of the melt compression area of the main feeding port can be increased to 150-160℃, for example 150℃, 152℃, 154℃, 156℃, 158℃, 160℃, to promote rapid dissolution of POE.

[0126] In the present application, the setting temperature of the melt delivery area can be increased to 160-170℃, for example 160℃, 162℃, 164℃, 166℃, 168℃, 170℃.

[0127] In the present application, the setting temperature of the side feeding port can be 170±5℃, for example 165℃, 166℃, 168℃, 170℃, 172℃, 175℃.

[0128] In some preferred embodiments, the temperature of the side feeding port is strictly controlled at 170℃.

[0129] In the present application, the setting temperature of the dispersion mixing section can be 165-168℃, for example 165℃, 166℃, 167℃, 168℃, and heat management is controlled by cooling water to control shear heat generation.

[0130] In the present application, the setting temperature of the exhaust section and the die can be 170±5℃, for example 165℃, 166℃, 168℃, 170℃, 172℃, 175℃.

[0131] In some preferred embodiments, the temperature of the exhaust section and the die can be 170℃.

[0132] In the present application, rapid cooling is carried out in the cooling section using 7-14℃ water, preferably at a temperature of 7-10℃, for example 7℃, 8℃, 9℃, 10℃, 11℃, 12℃, 13℃, 14℃.

[0133] In the present application, the setting of the blending screw speed of aramid pulp and polyolefin elastomer POE can be 100-400 rpm, preferably 100-300 rpm, further preferably 100-200 rpm, such as 100 rpm, 120 rpm, 140 rpm, 160 rpm, 180 rpm, 200 rpm, 220 rpm, 240 rpm, 260 rpm, 280 rpm, 300 rpm, 320 rpm, 340 rpm, 360 rpm, 380 rpm, 400 rpm, under the premise of stable feeding and dispersion.

[0134] The present application also provides an aramid rubber composite material, which comprises the aramid pulp composite polyolefin elastomer master batch and the rubber material.

[0135] In the present application, the rubber material can include natural rubber.

[0136] In the present application, the mass ratio of the aramid pulp composite polyolefin elastomer master batch and the rubber material can be (0.1-10):100, preferably (1-3):100, such as 0.1:100, 1:100, 1.5:100, 2:100, 2.5:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100.

[0137] The present application has the following beneficial effects:

[0138] The present application provides an efficient preparation method of aramid pulp composite polyolefin elastomer master batch, and is applied to rubber composite friction material. Polyolefin elastomer (POE) as the carrier of aramid pulp (AP) into rubber and the modifier of rubber matrix, is applied to natural rubber or synthetic rubber, not only solves the problem of difficult dispersion of AP, but also provides a path for large-scale production, and improves the wear resistance and tear resistance of the rubber composite material, and reduces the heat generated by friction.

[0139] The present application is in an intermediate state combining the traditional isolation method and the emulsion method, between the dry blending of the isolation method and the wet blending of the emulsion method. The operation steps and the introduction of various chemicals are reduced, and the processing cost is reduced to a certain extent.

[0140] The present application aims to solve the application problem of aramid pulp (AP) in rubber, and optimize the process steps and formula of AP master batch, reduce the introduction of chemicals with negative effects, thereby improving the comprehensive performance of the rubber composite material, and realizing the improvement of production efficiency and the reduction of production cost.

[0141] The present application will be described in the following with specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present application. The methods, reagents and materials used in the examples and comparative examples are conventional in the art unless otherwise specified. The starting compounds in the examples and comparative examples are all commercially available.

[0142] The specifications of the starting compounds in the examples and comparative examples are as follows:

[0143] Para aramid filament was purchased from China High Performance Fiber Materials Co., Ltd. with the specific model of SF2800 series and the linear density specification of 3000D;

[0144] Sorbitol glycidyl ether with a viscosity of 5000 mPa·s and an epoxy equivalent weight of 173 g / eq. was purchased from Nippon Shokubai Corporation with the specific model of PDS_EX-614B;

[0145] Amino-modified polysiloxane with a viscosity of 5 mPa·s and an active silane content of 40% was purchased from Wacker Chemie AG with the specific model of Dynasylan® HYDROSIL 1151;

[0146] POE with a density of 0.85-0.88 g / cm 3 , a crystallinity of 19%-21%, a Shore A hardness of 68-75, a melt flow rate of 5-20 g / 10 min @ 190°C, a tensile strength of 3.3-6.9 MPa, and a flexural modulus of 11.8-13.6 MPa was purchased from Dow Chemical Company with the specific model of ENGAGE8407;

[0147] Natural rubber was purchased from China High Performance Fiber Materials Co., Ltd. with the specific model of STR5L;

[0148] Zinc oxide was purchased from Anhui Huaxi with the specific model of ZnO-X;

[0149] Stearic acid was purchased from Evonik with the specific model of SA-1801;

[0150] Accelerator CZ was purchased from Yanggu Huatai with the specific model of CBS;

[0151] Insoluble sulfur S was purchased from Shandong Shangshun with the specific model of IS-60;

[0152] Antioxidant 6PPD was purchased from St. Omer Chemicals with the specific model of 4020;

[0153] Carbon black was purchased from Cabot with the specific model of N330.

[0154] Example 1

[0155] Example 1 provides aramid pulp and aramid pulp composite polyolefin elastomer masterbatch, the preparation steps are as follows:

[0156] (1) cut the para-aramid filament into para-aramid short-cut fiber with a length of 6mm;

[0157] (2) disperse sorbitol glycidyl ether and amino-modified polysiloxane in deionized water to obtain a modified solution, in the modified solution, the content of sorbitol glycidyl ether is 15wt%, the mass ratio of amino-modified polysiloxane to sorbitol glycidyl ether is 10:100; disperse the para-aramid short-cut fiber in the modified solution, the mass ratio of short-cut fiber to modified solution is 1:10, grind, then dry and open to obtain aramid pulp, the specific surface area of the obtained aramid pulp is 9.50-10.50g / m 2 , the fiber length is 0.90-1.10mm, and the Canadian freeness is 390-410mL;

[0158] (3) add masterbatch modifier amino-modified polysiloxane to the aramid pulp and mix uniformly to obtain a mixture, the mass of amino-modified polysiloxane is 40% of the mass of aramid pulp, and the mixture is added from the side feeding port in stages using a loss-in-weight feeder; POE particles are added from the main feeding port, the feeding temperature is 170℃; the mass of aramid pulp is 40% of the total mass of aramid pulp and POE; the mixture and POE are blended and extruded in a twin-screw extruder to obtain aramid pulp composite polyolefin elastomer masterbatch, which is denoted as masterbatch 1;

[0159] Among them, the processing temperature of the twin-screw extruder is set as follows: the temperature of the feeding zone of the main feeding port is 120℃, the temperature of the melt compression zone of the main feeding port is 155℃, the temperature of the melt conveying zone is 165℃; the temperature of the side feeding port is 170℃; the temperature of the dispersion mixing section is 165-168℃; the temperature of the exhaust section and the die is 170℃; the cooling section is cooled by water at 7-10℃. The screw rotation speed of the screw extruder is 150rpm.

[0160] Example 2

[0161] Example 2 provides aramid pulp and aramid pulp composite polyolefin elastomer masterbatch, the preparation steps are basically the same as those of Example 1, the only difference is that in step (2), the modified solution contains 10wt% sorbitol glycidyl ether, and the mass ratio of amino-modified polysiloxane to sorbitol glycidyl ether is still 10:100.

[0162] The specific surface area of the obtained aramid pulp is 9.50-10.50g / m 2 , the fiber length is 0.90-1.10mm, and the Canadian freeness is 390-410mL.

[0163] The final aramid pulp composite polyolefin elastomer masterbatch is recorded as masterbatch 2.

[0164] Example 3

[0165] Example 3 provides aramid pulp and aramid pulp composite polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the difference is only in step (2), the modified solution contains 20wt% sorbitol glycidyl ether, the mass ratio of amino modified polysiloxane to sorbitol glycidyl ether is still 10:100.

[0166] The specific surface area of the obtained aramid pulp is 9.50-10.50g / m 2 , the fiber length is 0.90-1.10mm, and the Canadian freeness is 390-410mL.

[0167] The final aramid pulp composite polyolefin elastomer masterbatch is recorded as masterbatch 3.

[0168] Example 4

[0169] Example 4 provides aramid pulp and aramid pulp composite polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the difference is only in step (2), the modified solution contains 15wt% sorbitol glycidyl ether, but the mass ratio of amino modified polysiloxane to sorbitol glycidyl ether is 5:100.

[0170] The specific surface area of the obtained aramid pulp is 9.50-10.50g / m 2 , the fiber length is 0.90-1.10mm, and the Canadian freeness is 390-410mL.

[0171] The final aramid pulp composite polyolefin elastomer masterbatch is recorded as masterbatch 4.

[0172] Example 5

[0173] Example 5 provides aramid pulp and aramid pulp composite polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the difference is only in step (2), the modified solution contains 15wt% sorbitol glycidyl ether, but the mass ratio of amino modified polysiloxane to sorbitol glycidyl ether is 15:100.

[0174] The specific surface area of the obtained aramid pulp is 9.50-10.50g / m 2 , the fiber length is 0.90-1.10mm, and the Canadian freeness is 390-410mL.

[0175] The final aramid pulp composite polyolefin elastomer masterbatch is recorded as masterbatch 5.

[0176] Example 6

[0177] Example 6 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the difference is only in step (3), the mass of amino modified polysiloxane is 30% of the mass of aramid pulp.

[0178] The final aramid pulp compounded polyolefin elastomer masterbatch is recorded as masterbatch 6.

[0179] Example 7

[0180] Example 7 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the difference is only in step (3), the mass of amino modified polysiloxane is 50% of the mass of aramid pulp.

[0181] The final aramid pulp compounded polyolefin elastomer masterbatch is recorded as masterbatch 7.

[0182] Example 8

[0183] Example 8 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the difference is only in step (3), the mass of aramid pulp is 30% of the total mass of aramid pulp and POE.

[0184] The final aramid pulp compounded polyolefin elastomer masterbatch is recorded as masterbatch 8.

[0185] Example 9

[0186] Example 9 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the difference is only in step (2), the amino modified polysiloxane is replaced by equal mass of N-(n-butyl)-3-aminopropyl trimethoxysilane.

[0187] The specific surface area of the obtained aramid pulp is 9.50-10.50 g / m 2 , the fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0188] The final aramid pulp compounded polyolefin elastomer masterbatch is recorded as masterbatch 9.

[0189] Example 10

[0190] Example 10 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the difference is only in step (2), the amino modified polysiloxane is replaced by equal mass of bis[3-(triethoxysilyl)propyl]amine.

[0191] The specific surface area of the obtained aramid pulp is 9.50-10.50 g / m2 The fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0192] The final aramid pulp composite polyolefin elastomer masterbatch is recorded as masterbatch 10.

[0193] Example 11

[0194] Example 11 provides aramid pulp and aramid pulp composite polyolefin elastomer masterbatch, the preparation steps are basically the same as those of Example 1, and the only difference is that in step (2), the amino-modified polysiloxane is replaced with equal mass of 3-aminopropyltriethylsiloxane.

[0195] The specific surface area of the obtained aramid pulp is 9.50-10.50 g / m 2 The fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0196] The final aramid pulp composite polyolefin elastomer masterbatch is recorded as masterbatch 11.

[0197] Example 12

[0198] Example 12 provides aramid pulp and aramid pulp composite polyolefin elastomer masterbatch, the preparation steps are basically the same as those of Example 1, and the only difference is that in step (2), the amino-modified polysiloxane is replaced with equal mass of triamino-functionalized propyltrimethoxysilane.

[0199] The specific surface area of the obtained aramid pulp is 9.50-10.50 g / m 2 The fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0200] The final aramid pulp composite polyolefin elastomer masterbatch is recorded as masterbatch 12.

[0201] Example 13

[0202] Example 13 provides aramid pulp and aramid pulp composite polyolefin elastomer masterbatch, the preparation steps are basically the same as those of Example 1, and the only difference is that in step (2), the sorbitol glycidyl ether is replaced with equal mass of glycerol triglycidyl ether.

[0203] The specific surface area of the obtained aramid pulp is 9.50-10.50 g / m 2 The fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0204] The final aramid pulp composite polyolefin elastomer masterbatch is recorded as masterbatch 13.

[0205] Example 14

[0206] Example 14 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the only difference is that in step (2), sorbitol glycidyl ether is replaced by equal mass of pentaerythritol tetraglycidyl ether.

[0207] The specific surface area of the obtained aramid pulp is 9.50-10.50 g / m 2 , the fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0208] The final aramid pulp compounded polyolefin elastomer masterbatch is recorded as masterbatch 14.

[0209] Example 15

[0210] Example 15 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the only difference is that in step (2), sorbitol glycidyl ether is replaced by equal mass of diglycerol polyglycidyl ether.

[0211] The specific surface area of the obtained aramid pulp is 9.50-10.50 g / m 2 , the fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0212] The final aramid pulp compounded polyolefin elastomer masterbatch is recorded as masterbatch 15.

[0213] Example 16

[0214] Example 16 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the only difference is that in step (2), sorbitol glycidyl ether is replaced by equal mass of trimethylolpropane polyglycidyl ether.

[0215] The specific surface area of the obtained aramid pulp is 9.50-10.50 g / m 2 , the fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0216] The final aramid pulp compounded polyolefin elastomer masterbatch is recorded as masterbatch 16.

[0217] Example 17

[0218] Example 17 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the only difference is that in step (2), sorbitol glycidyl ether is replaced by equal mass of lignin oil alcohol soluble phenolic polyglycidyl ether.

[0219] The specific surface area of the obtained aramid pulp is 9.50-10.50 g / m 2 , the fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0220] The finally obtained aramid pulp compounded polyolefin elastomer masterbatch is recorded as masterbatch 17.

[0221] Comparative Example 1

[0222] Comparative Example 1 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, and the preparation steps are basically the same as those of Example 1, the only difference being that in step (2), the short-cut fibers are directly dispersed in deionized water for grinding, drying and opening to obtain aramid pulp.

[0223] The specific surface area of the obtained aramid pulp is 9.5-10.50 g / m 2 , the fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0224] The finally obtained aramid pulp compounded polyolefin elastomer masterbatch is recorded as comparative masterbatch 1.

[0225] Comparative Example 2

[0226] Comparative Example 2 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, and the preparation steps are basically the same as those of Example 1, the only difference being that in step (2), the modified solution contains 15 wt% sorbitol glycidyl ether and no amino-modified polysiloxane.

[0227] The specific surface area of the obtained aramid pulp is 9.5-10.50 g / m 2 , the fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0228] The finally obtained aramid pulp compounded polyolefin elastomer masterbatch is recorded as comparative masterbatch 2.

[0229] Comparative Example 3

[0230] Comparative Example 3 provides aramid pulp and aramid pulp compounded polyolefin elastomer masterbatch, and the preparation steps are basically the same as those of Example 1, the only difference being that in step (2), the modified solution contains 1.5 wt% amino-modified polysiloxane and no sorbitol glycidyl ether.

[0231] The specific surface area of the obtained aramid pulp is 9.5-10.50 g / m 2 , the fiber length is 0.90-1.10 mm, and the Canadian freeness is 390-410 mL.

[0232] The final aramid pulp composite polyolefin elastomer masterbatch is denoted as comparative masterbatch 3.

[0233] Comparative example 4

[0234] Comparative example 4 provides aramid pulp and aramid pulp composite polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the difference is only in step (2), the existing phenolic system modifier is dispersed in deionized water to obtain a modified solution, and the content of the phenolic system modifier in the modified solution is 16.5wt%.

[0235] The specific surface area of the obtained aramid pulp is 9.5-10.50g / m 2 , the fiber length is 0.90-1.10mm, and the Canadian freeness is 390-410mL.

[0236] Because the phenolic system modifier is a macromolecule with poor processing performance, the modified aramid pulp cannot be prepared into a masterbatch by blending and extruding with POE particles through a twin-screw extruder, so comparative masterbatch 4 cannot be obtained.

[0237] Comparative example 5

[0238] Comparative example 5 provides aramid pulp and aramid pulp composite polyolefin elastomer masterbatch, the preparation steps are basically the same as example 1, the difference is only in step (3), the masterbatch modifier amino-modified polysiloxane is replaced with equal mass of methyl triethoxysilane.

[0239] The final aramid pulp composite polyolefin elastomer masterbatch is denoted as comparative masterbatch 5.

[0240] Application example 1

[0241] In this application example, vulcanized rubbers 1-26 are prepared according to the vulcanized rubber formulations shown in Tables 1-1, 1-2 and Table 1-3, using the masterbatches prepared in examples 1-17 and comparative examples 1-3, 5 and other raw materials. Among them, the difference between the formulations of vulcanized rubbers 18-26 and vulcanized rubber 3 is only that masterbatch 1 is replaced by masterbatches 9-17 of the same parts.

[0242] The specific preparation process is as follows:

[0243] (1) Use the open mill mixing bag roller: put the natural rubber raw rubber into the roller cylinder of the open mill, and thin pass the natural rubber raw rubber until a continuous and smooth bag roller layer is formed on the surface of the roller cylinder;

[0244] (2) After the raw rubber is completed, add carbon black, zinc oxide, stearic acid, and antioxidant to the roller cylinder of the open mill in turn. After adding each kind of small material, respectively cut the knife along the left and right sides of the roller cylinder of the open mill, and the number of cutting knives on each side is 3 times, to ensure that the small materials are uniformly dispersed in the rubber matrix;

[0245] (3) After the small material is evenly dispersed, the aramid pulp composite polyolefin elastomer masterbatch is added into the roller cylinder in batches and slowly. The cutter is continuously operated during the masterbatch powder feeding process to prevent the masterbatch from sticking to the roller, until the masterbatch and the rubber matrix are fully mixed and there is no powder particle;

[0246] (4) The roller gap of the open mill is adjusted to be small, and the rubber material is processed by triangular bag. Then, the accelerator CZ and sulfur are added into the roller cylinder, and the cutter is operated along the left and right sides of the roller cylinder for 3 times respectively after the addition, and the triangular bag is continued to be processed, until the vulcanization system and the rubber material are fully mixed. Finally, the roller gap of the open mill is adjusted to be large, and the mixed rubber material is sheeted out, cooled, and stored for at least 8 hours before vulcanization.

[0247] (5) The vulcanization conditions are as follows: the vulcanization temperature is 150°C, and the T90 (vulcanization time) is measured by a rotorless vulcanization instrument. According to the formula, the T90 is between 5-10 minutes, and the actual measurement is 8 minutes.

[0248] Table 1-1: Vulcanized rubber formula (unit: parts phr)

[0249]

[0250] Table 1-2: Vulcanized rubber formula (unit: parts phr)

[0251]

[0252] Table 1-3: Vulcanized rubber formula (unit: parts phr)

[0253]

[0254] Test Example

[0255] I. Modifier content test

[0256] The solvent extraction method is used to test the mass percentage content (coating amount) of the modifier used in Examples 1-5, Examples 9-17 and Comparative Example 2 in the corresponding aramid pulp, and the specific steps are as follows:

[0257] (1) The initial mass of the dried aramid pulp (W1) is accurately weighed;

[0258] (2) The Soxhlet extractor is used, and dimethylformamide (DMF) is used as the solvent to extract the aramid pulp at about 80°C for 2 hours to completely remove the modifier;

[0259] (3) Then, the extracted aramid pulp is dried again to constant weight, and its final mass (W2) is weighed. The accurate mass percentage (coating amount) can be calculated by the formula [(W1 - W2) / W2] x 100%.

[0260] The results are shown in Table 2.

[0261] Table 2: Modifier content of aramid pulp

[0262]

[0263] The total content of the first modifier and the second modifier in the aramid pulp of Examples 9-17 is between 1wt%-5.5wt%.

[0264] II. Shore A hardness and tear strength of vulcanized rubber

[0265] The Shore A hardness and tear strength of the vulcanized rubber 1-26 prepared in Application Example 1 were tested, and the test results are shown in Table 3.

[0266] The test method for Shore A hardness is as follows:

[0267] According to GB / T 531.1-2008 "Vulcanized or thermoplastic rubber - Determination of indentation hardness - Part 1: Durometer method (Shore hardness)", the Shore A hardness test is used to quickly evaluate the softness and hardness of rubber. Using a Shore A durometer, a specific gauge needle is vertically pressed into the surface of the rubber sample under its standard spring pressure. By reading the position of the needle rebound, the hardness value is directly obtained on the dial, with units of "degrees" or "HA". The test is performed in the middle of the sample, with 5 measurements taken, and the entire process from indentation to reading must be completed within 3 seconds. The test results are measured and counted.

[0268] The test method for tear strength is as follows:

[0269] According to GB / T 529-2008 "Determination of tear strength of vulcanized or thermoplastic rubber", the tear strength test is used to measure the ability of rubber to resist crack propagation. A crescent-shaped sample with a pre-made cut is usually used, which is clamped in the upper and lower clamps of a tensile testing machine. The sample is stretched at a constant speed of 500 mm / min until it is completely torn. The maximum tensile force during the entire process is recorded, and the value is divided by the thickness of the sample to finally calculate the tear strength, with units of kN / m.

[0270] Table 3: Test results of Shore A hardness and tear strength of vulcanized rubber 1-17

[0271]

[0272] The Shore A hardness and tear strength of vulcanized rubber 18-26 are higher than those of vulcanized rubber 1.

[0273] As can be seen from the experimental results of vulcanized rubbers 1-4 in Table 3, with the increase of the addition amount of 40% AP-POE, the Shore A hardness and tear strength of vulcanized rubbers 1-4 gradually increase, which represents that the wear resistance and tear resistance increase with the increase of the addition amount of aramid pulp composite polyolefin elastomer masterbatch.

[0274] As can be seen from the experimental results of vulcanized rubbers 3, 6 in Table 3, the Shore A hardness and tear strength of the vulcanized rubber prepared by simultaneously adding sorbitol glycidyl ether and amino-modified polysiloxane in aramid pulp are better than those of the vulcanized rubber prepared without adding the two substances.

[0275] As can be seen from the experimental results of vulcanized rubbers 3, 15, 16 in Table 3, the Shore A hardness and tear strength of the vulcanized rubber prepared by simultaneously adding sorbitol glycidyl ether and amino-modified polysiloxane in aramid pulp are better than those of the vulcanized rubber prepared by adding only one of the two substances.

[0276] As can be seen from the experimental results of vulcanized rubbers 3, 17 in Table 3, the Shore A hardness and tear strength of the vulcanized rubber prepared by adding amino-modified polysiloxane masterbatch modifier in aramid pulp composite polyolefin elastomer are better than those of the vulcanized rubber prepared by adding other conventional masterbatch modifiers.

[0277] As can be seen from the experimental results of vulcanized rubbers 3, 6, 17 in Table 3, the addition of amino-modified polysiloxane masterbatch modifier in aramid pulp composite polyolefin elastomer has a positive effect on the preparation of vulcanized rubber, and an inappropriate masterbatch modifier such as methyl triethoxysilane has no positive effect on the preparation of vulcanized rubber.

[0278] III. Storage modulus test

[0279] The storage modulus G' of the vulcanized rubbers 1-4 prepared in Examples 1-4 was tested, and the test results are shown in Table 4.

[0280] The test method of storage modulus is as follows:

[0281] According to the ASTM D6204 (determination of rubber properties) standard, the RPA test of vulcanized rubber is based on the principle of oscillatory shear, the vulcanized rubber sample is placed in a closed mold cavity, a controlled strain or stress is applied to it, and it is subjected to sinusoidal oscillation. By measuring the stress or strain response generated, the viscoelastic data of the material is obtained.

[0282] Storage modulus calculation method: Storage modulus (G') is calculated from the phase angle between stress and strain signals. In viscoelastic rubbers, stress will lead strain by a phase angle (delta), the calculation formula is: G' = (stress amplitude / strain amplitude) x cos(delta), which is automatically completed by the instrument software, and its results directly represent the ability of the material to store elastic deformation energy.

[0283] Table 4: Storage modulus test results of vulcanized rubbers 1-4

[0284]

[0285] As can be seen from Table 4, with the increase of the addition amount of 40% AP-POE, the storage modulus G' of vulcanized rubbers 1-4 gradually decreases, representing that the friction heat generation decreases with the increase of the addition amount of aramid pulp composite polyolefin elastomer masterbatch.

Claims

1. An aramid pulp, characterized in that, The aramid pulp includes a first modifier and a second modifier, wherein the first modifier is a glycidyl ether compound and the second modifier is an amino-containing siloxane compound.

2. The aramid pulp as described in claim 1, characterized in that, The aramid pulp has one or more of the following characteristics: The first modifier is selected from one or more of sorbitol glycidyl ether, glycerol triglycidyl ether, pentaerythritol tetraglycidyl ether, diglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, and lignocellulosic alcohol soluble phenolic polyglycidyl ether; preferably, the first modifier is sorbitol glycidyl ether; preferably, the viscosity of the sorbitol glycidyl ether is 5000±500 mPa·s, and the epoxy equivalent is 173±10 g / eq.; The second modifier is selected from one or more of amino-modified polysiloxane, N-(n-butyl)-3-aminopropyltrimethoxysilane, bis[3-(triethoxysilane)propyl]amine, 3-aminopropyltriethylsiloxane, and triamino-functionalized propyltrimethoxysilane; preferably, the second modifier is selected from amino-modified polysiloxane; preferably, the viscosity of the amino-modified polysiloxane is 5±1 mPa·s, the active silane content is 40±10%, and the amino content is 10%-22%; The first modifier and the second modifier account for 1wt%-5.5wt% of the total mass of the aramid pulp, preferably 4wt%-5wt%. The mass ratio of the second modifier to the first modifier is (5-15):100, preferably (9-11):100; The aramid pulp is para-aramid pulp; The aramid pulp has a fiber length of 0.8-1.3 mm; The specific surface area of ​​the aramid pulp is 6.50-11.50 g / m². 2 ; The freeness of the aramid pulp in Canada is 340-460 mL.

3. A method for preparing the aramid pulp according to claim 1 or 2, characterized in that, The method includes the following steps: (1) Provide chopped fibers; (2) The chopped fibers are dispersed in a modified solution and ground, and the ground wet pulp is dried and opened to obtain the aramid pulp; The modified solution is an aqueous solution containing the first modifier and the second modifier.

4. The method as described in claim 3, characterized in that, The method has one or more of the following characteristics: The chopped fibers are cut from aramid filaments; The length of the chopped fibers is 4-10 mm; In the modified solution, the content of the first modifier is 10wt%-20wt%, preferably 15±1wt%; In the modified solution, the mass ratio of the second modifier to the first modifier is (5-15):100, preferably (9-11):100; The mass ratio of the chopped fibers to the modified solution is 1:(10-15).

5. An aramid pulp composite polyolefin elastomer masterbatch, characterized in that, The aramid pulp composite polyolefin elastomer masterbatch includes the aramid pulp, polyolefin elastomer, and masterbatch modifier as described in claim 1 or 2.

6. The aramid pulp composite polyolefin elastomer masterbatch as described in claim 5, characterized in that, The aramid pulp composite polyolefin elastomer masterbatch has one or more of the following characteristics: The polyolefin elastomer is an ethylene octene copolymer; The density of the polyolefin elastomer is 0.85-0.88 g / cm³. 3 ; The crystallinity of the polyolefin elastomer is 19-21%; The Shore A hardness of the polyolefin elastomer is 68-75; The melt flow rate of the polyolefin elastomer is 5-20 g / 10 min at 190 °C. The tensile strength of the polyolefin elastomer is 3.3-6.9 MPa; The flexural modulus of the polyolefin elastomer is 11.8-13.6 MPa; The masterbatch modifier is selected from one or both of the first modifier and the second modifier. The first modifier is a glycidyl ether compound, and the second modifier is an amino-containing siloxane compound. Preferably, the first modifier is selected from one or more of sorbitol glycidyl ether, glycerol triglycidyl ether, pentaerythritol tetraglycidyl ether, diglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, and lignotar alcohol soluble phenolic polyglycidyl ether. The second modifier is selected from one or more of amino-modified polysiloxane, N-(n-butyl)-3-aminopropyltrimethoxysilane, bis[3-(triethoxysilyl)propyl]amine, 3-aminopropyltriethylsiloxane, and triaminofunctionalized propyltrimethoxysilane. Preferably, the masterbatch modifier is an amino-modified polysiloxane. Preferably, the amino-modified polysiloxane has a viscosity of 5±1 mPa·s, an active silane content of 40±10%, and an amino content of 10%-22%. In the aramid pulp composite polyolefin elastomer masterbatch, the mass of the aramid pulp is 10%-60% of the total mass of the aramid pulp and the polyolefin elastomer, preferably 20%-50%, and more preferably 30%-40%. In the aramid pulp composite polyolefin elastomer masterbatch, the mass of the masterbatch modifier is 30%-50% of the mass of the aramid pulp, preferably 40±5%.

7. A method for preparing the aramid pulp composite polyolefin elastomer masterbatch according to claim 5 or 6, characterized in that, The method includes: adding the mixture of the aramid pulp and the masterbatch modifier into a screw extruder, adding the polyolefin elastomer into the screw extruder, and co-extruding the mixture and the polyolefin elastomer in the screw extruder to obtain the aramid pulp composite polyolefin elastomer masterbatch.

8. The method as described in claim 7, characterized in that, The method has one or more of the following characteristics: The screw extruder is a twin-screw extruder; The polyolefin elastomer is added from the main feed port; Add the mixture from the side feed port; The feeding temperature of the polyolefin elastomer is 160-180℃, preferably 170±5℃; The mixture is fed using a loss-in-weight feeder; The processing temperatures of the screw extruder are set as follows: the temperature of the feeding zone at the main feed port is 110-130℃; the temperature of the melt compression zone at the main feed port is 150-160℃; the temperature of the melt conveying zone is 160-170℃; the temperature of the side feed port is 170±5℃; the temperature of the dispersion and mixing section is 165-168℃; the temperature of the venting section and the die head is 170±5℃; and the cooling section is cooled with water at 7-14℃, preferably 7-10℃. The screw speed of the screw extruder is 100-400 rpm, preferably 100-300 rpm, and more preferably 100-200 rpm.

9. An aramid rubber composite material, characterized in that, The aramid rubber composite material comprises the aramid pulp composite polyolefin elastomer masterbatch and rubber material as described in claim 5 or 6.

10. The aramid rubber composite material as described in claim 9, characterized in that, The rubber material includes natural rubber; and / or The mass ratio of the aramid pulp composite polyolefin elastomer masterbatch to the rubber material is (0.1-10):100, preferably (1-3):100.

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