CN117051591A - Aramid pulp modification treatment method, aramid pulp pre-dispersion and application thereof - Google Patents

Aramid pulp modification treatment method, aramid pulp pre-dispersion and application thereof Download PDF

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Publication number
CN117051591A
CN117051591A CN202311316575.XA CN202311316575A CN117051591A CN 117051591 A CN117051591 A CN 117051591A CN 202311316575 A CN202311316575 A CN 202311316575A CN 117051591 A CN117051591 A CN 117051591A
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aramid pulp
rubber
aramid
pulp
dispersion
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耿晓燕
邓钧波
王忠华
丁琳琳
吕娜
韩尊强
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Yantai Taihexing Material Technology Co ltd
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Yantai Taihexing Material Technology Co ltd
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    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
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    • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
    • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
    • D06M15/37—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L11/00—Compositions of homopolymers or copolymers of chloroprene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/16—Elastomeric ethene-propene or ethene-propene-diene copolymers, e.g. EPR and EPDM rubbers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L7/00—Compositions of natural rubber
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
    • C08L9/02—Copolymers with acrylonitrile
    • D—TEXTILES; PAPER
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    • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
    • D06M13/10—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing oxygen
    • D06M13/224—Esters of carboxylic acids; Esters of carbonic acid
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
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    • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
    • D06M13/50—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with organometallic compounds; with organic compounds containing boron, silicon, selenium or tellurium atoms
    • D06M13/51—Compounds with at least one carbon-metal or carbon-boron, carbon-silicon, carbon-selenium, or carbon-tellurium bond
    • D06M13/513—Compounds with at least one carbon-metal or carbon-boron, carbon-silicon, carbon-selenium, or carbon-tellurium bond with at least one carbon-silicon bond
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    • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
    • D06M13/50—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with organometallic compounds; with organic compounds containing boron, silicon, selenium or tellurium atoms
    • D06M13/51—Compounds with at least one carbon-metal or carbon-boron, carbon-silicon, carbon-selenium, or carbon-tellurium bond
    • D06M13/513—Compounds with at least one carbon-metal or carbon-boron, carbon-silicon, carbon-selenium, or carbon-tellurium bond with at least one carbon-silicon bond
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    • D06M23/00—Treatment of fibres, threads, yarns, fabrics or fibrous goods made from such materials, characterised by the process
    • D—TEXTILES; PAPER
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    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M2101/00—Chemical constitution of the fibres, threads, yarns, fabrics or fibrous goods made from such materials, to be treated
    • D06M2101/16—Synthetic fibres, other than mineral fibres
    • D06M2101/30—Synthetic polymers consisting of macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D06M2101/34—Polyamides
    • D06M2101/36—Aromatic polyamides

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  • Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

Abstract

The invention belongs to the field of aramid fiber application, and provides an aramid fiber pulp modification treatment method and application, wherein the modification treatment method adopts dopamine and silane coupling agent, carries out surface modification on aramid fiber pulp short fibers in water, and obtains blocky aramid fiber pulp through drying; applying a lubricant after loosening the blocky aramid pulp to obtain modified aramid pulp; the lubricant is selected from one or more of phthalic acid esters and fatty dibasic acid esters. The dopamine adopted by the invention can have an isolation effect by self-aggregation; and a large number of hydroxyl groups and other groups are introduced into the surface after grafting by the silane coupling agent, so that the grafting agent can be combined with rubber to generate chemical bonds, and the dispersibility of the aramid pulp in the rubber and the interfacial adhesion of the aramid pulp and the rubber are improved. The whole modification process is completed in an aqueous solution, and the modification of the aramid fiber material is completed in one step; and then opening and applying the lubricant to obtain the modified aramid pulp, which has simple operation steps and obvious modification effect and is beneficial to the application of pre-dispersion and reinforced rubber.

Description

Aramid pulp modification treatment method, aramid pulp pre-dispersion and application thereof
Technical Field
The invention belongs to the technical field of aramid fiber application, and particularly relates to an aramid fiber pulp modification treatment method, an aramid fiber pulp pre-dispersion and application thereof.
Background
The aramid fiber with wide practicability mainly comprises: para-aramid fibers (para-aramid fibers) and meta-aramid fibers (meta-aramid fibers); the aramid pulp is generally obtained by carrying out surface fibrillation treatment on aramid fibers, and is very suitable for being used as a reinforcing fiber material. The para-aramid pulp has a good reinforcing effect on rubber, but the para-aramid pulp has poor dispersibility in rubber and cannot effectively exert the reinforcing effect of pulp.
At present, aramid pulp is modified to prepare an aramid pulp pre-dispersion, and the prepared aramid pulp pre-dispersion can enable the aramid pulp to have better dispersibility in rubber, so that the strength and fatigue resistance of rubber products are better improved. For example, chinese patent No. CN201410241448.2 discloses a method for preparing an aramid pulp masterbatch, in which an aramid pulp, an isolating dispersant and a binder resin are first mixed by high-speed stirring to obtain a surface-modified aramid pulp, and then mixed with a rubber matrix such as Natural Rubber (NR) to prepare the masterbatch.
In the para-aramid pulp modification treatment process, the selected adhesive resin is epoxy resin, phenolic resin and the like, and the selected isolation dispersing agent is paraffin oil, naphthenic oil, butyl benzyl phthalate and the like; the aramid pulp short fibers can be uniformly dispersed in a small amount of rubber matrix to a certain extent, but the dispersibility of the aramid pulp in the rubber and the interfacial stability of the aramid pulp and the rubber still need to be further improved so as to be beneficial to reinforcing the rubber.
Disclosure of Invention
The invention provides an aramid pulp modification treatment method, an aramid pulp pre-dispersion and application thereof, and the aramid pulp pre-dispersion prepared by the method can ensure that the aramid pulp has better dispersibility in rubber, thereby effectively improving the strength and fatigue resistance of the rubber and being beneficial to application.
The invention provides an aramid pulp modification treatment method, which comprises the following steps:
carrying out surface modification on the aramid pulp short fiber in water by adopting dopamine and silane coupling agent, and drying to obtain blocky aramid pulp;
applying a lubricant after loosening the blocky aramid pulp to obtain modified aramid pulp;
the mass ratio of the dopamine to the silane coupling agent to the aramid pulp is 1-2: 0.5-2: 30-50 parts; the lubricant is selected from one or more of dibutyl phthalate, dioctyl adipate and dioctyl azelate; the viscosity of the lubricant is less than or equal to 100 mPa.s at 25 ℃; the mass ratio of the lubricant to the aramid pulp short fiber is 17.5-23: 30-50 parts; the lubricant is sprayed on the opened aramid pulp in a droplet mist form.
In an embodiment of the present invention, the silane coupling agent is selected from one or more of KH550, KH560, and KH 570.
In the embodiment of the invention, the aperture of the spray nozzle is 2-7 mm, and the flow range is 1-20L/min.
The invention provides an aramid pulp pre-dispersion, which is obtained by premixing modified aramid pulp obtained by the modification treatment method with a rubber matrix and then carrying out a molding process.
In an embodiment of the invention, the rubber matrix is selected from one or more of natural rubber, nitrile rubber, neoprene rubber and ethylene propylene diene rubber.
In an embodiment of the invention, the aramid pulp pre-dispersion further comprises a plasticizer, preferably stearic acid.
The invention also provides application of the aramid pulp pre-dispersion as a rubber reinforcing material.
In an embodiment of the invention, the aramid pulp pre-dispersion prepares a reinforced natural rubber composite; the preparation raw materials comprise: 100 parts by mass of natural rubber; 20-25 parts by mass of an aramid pulp pre-dispersion; preferably, the adhesive further comprises 1-2 parts by mass of a cross-linking agent and 15-20 parts by mass of white carbon black.
Compared with the prior art, the method mainly utilizes the dopamine and silane coupling agent to modify the aramid pulp, the dopamine is oxidized in the aqueous solution, then self-polymerization-crosslinking reaction is initiated, the polydopamine has viscosity and a structure similar to viscous protein, and can be tightly adhered to the surface of some solid materials, so that a uniform deposition layer is formed on the surface of the aramid pulp, and the isolation effect is mainly achieved; and a large number of hydroxyl groups and other groups are introduced into the surface after grafting by the silane coupling agent, so that the grafting agent can be combined with rubber to generate chemical bonds, and the dispersibility of the aramid pulp in the rubber and the interfacial adhesion of the aramid pulp and the rubber are improved. The whole modification process is completed in an aqueous solution, and the modification of the aramid short fiber material is completed in one step; and then opening and atomizing to spray a specific lubricant (the viscosity is less than or equal to 100 mPa.s at 25 ℃), so that the modified aramid pulp is simple in operation steps, obvious in modification effect and beneficial to pre-dispersion and application in reinforced rubber.
In the invention, the addition of the special lubricant adopts an atomization form and is sprayed on the surface of the fluffy para-aramid pulp. The adding proportion of the lubricant is far lower than the absorption capacity of the aramid pulp, so that the lubricant is absorbed by the local aramid pulp when directly added, the effect of uniform dispersion is difficult to achieve, and the dispersibility of the aramid pulp in rubber is affected. The adding mode of the invention can ensure that the lubricant is uniformly dispersed in the aramid pulp, and the prepared aramid pulp pre-dispersion can ensure that the aramid pulp has better dispersibility in rubber and improve the strength and fatigue resistance of the rubber.
Drawings
FIG. 1 is a 1 micron SEM photograph of an aramid pulp treated with dopamine and silane coupling agent in example 1 of the present invention;
FIG. 2 is a nano-scale SEM photograph of the aramid pulp treated with the dopamine and silane coupling agent in example 1 of the present invention;
FIG. 3 is a 1 micron SEM photograph of an aramid pulp staple fiber (untreated) of comparative example 1 of the present invention.
Detailed Description
In order that those skilled in the art will better understand the technical solutions of the present invention, the following detailed description of the present invention with reference to specific embodiments thereof is provided for exemplary and explanatory purposes only and should not be construed as limiting the scope of the present invention.
The invention provides an aramid pulp modification treatment method, which comprises the following steps:
carrying out surface modification on the aramid pulp short fiber in water by adopting dopamine and silane coupling agent, and drying to obtain blocky aramid pulp;
applying a lubricant after loosening the blocky aramid pulp to obtain modified aramid pulp;
the mass ratio of the dopamine to the silane coupling agent to the aramid pulp is 1-2: 0.5-2: 30-50 parts; the lubricant is selected from one or more of phthalic acid esters (dibutyl phthalate and/or dioctyl phthalate) and fatty dibasic acid esters (dioctyl adipate and/or dioctyl azelate); the viscosity of the lubricant is less than or equal to 100 mPa.s at 25 ℃; the mass ratio of the lubricant to the aramid pulp short fiber is 17.5-23: 30-50 parts; the lubricant is sprayed on the opened aramid pulp in a droplet mist form.
The modified aramid pulp and the pre-dispersion thereof prepared by the method can ensure that the aramid pulp has better dispersibility in rubber, thereby effectively improving the strength and fatigue resistance of the rubber.
According to the embodiment of the invention, a dopamine salt aqueous solution with a certain mass concentration is prepared, weak base such as tris (hydroxymethyl) aminomethane is added to adjust the pH value of the solution to 8-9, the raw material aramid pulp is added into the prepared dopamine salt aqueous solution according to the proportion, after stirring and reacting for a certain time, a silane coupling agent is added into the solution, the stirring and reacting are continued, and the treated aramid pulp is taken out and dried to obtain the blocky aramid pulp.
In the embodiment of the invention, dopamine and a silane coupling agent are used as modifiers of aramid pulp, and are modified in an aqueous solution; the mass ratio of the dopamine to the silane coupling agent to the aramid pulp is 0.8-2: 0.5-2: 30-50, preferably 1-2: 0.5 to 1.5: 30-50. Wherein, 2.0g/L of dopamine salt water solution can be prepared, 30 g-50 g of raw material aramid pulp is added into 0.5L-1.0L of dopamine salt water solution, and then 0.5 g-2.0 g of silane coupling agent is added.
In the embodiment of the invention, aramid pulp is prepared from the following components in parts by mass: 30-50 parts of a lubricant; and (3) a modifier: 0.8-2.0 parts of dopamine; preferably the coupling agent: KH550, KH560 or KH570 0.5-2.0 parts. Length of the aramid pulp fiber: 0.85-1.35mm, and specific surface area of 9-15m 2 And/g. The embodiment of the invention can adopt raw materials such as dopamine hydrochloride and the like which are sold in the market; the conventional stirring reaction is carried out for 4-5 hours, the dopamine is oxidized in the aqueous solution, then the self-polymerization-crosslinking reaction is initiated, and the dopamine can be tightly adhered to the surface of the aramid pulp to form a uniform deposition layer.
In an embodiment of the invention, the coupling agent KH-550 is 3-aminopropyl triethoxysilane, KH-560 is epoxy functional silane, the chemical name is gamma- (2, 3-glycidoxy) propyl trimethoxysilane, and the silane coupling agent KH-570 is gamma-methacryloxypropyl, also known as silane coupling agent G-570. After adding the dopamine, adding the silane coupling agent, and continuously stirring for reacting for 2-3 hours; the silane coupling agent can be grafted on the surface of the aramid pulp short fiber, and a large number of hydroxyl groups and epoxy groups are introduced, so that the silane coupling agent can be chemically bonded with a rubber matrix. In addition, the reaction process is carried out in water, and the operation is simple.
In the embodiment of the invention, in opening equipment, the dried blocky aramid pulp is opened to a fluffy state; for example, 5kg of blocky aramid pulp can be placed into 400L of opening equipment, the fly cutter rotating speed is 2300-2600 r/min, stirring is rotated for 50-60 r/min, and the obtained product is taken out after opening for 5-10 minutes.
According to the embodiment of the invention, the lubricant is sprayed on fluffy aramid pulp in a mist mode, and the aramid pulp can be stirred at the same time, so that uniform modified aramid pulp is obtained.
In the present invention, the lubricant is selected from one or more of phthalic acid esters (dibutyl phthalate and/or dioctyl phthalate) and fatty dibasic acid esters (dioctyl adipate and/or dioctyl azelate). And the mass ratio of the lubricant to the aramid pulp raw material is 16-23: 30-50, such as 17.5-23: 30-50.
In the embodiment of the invention, the atomization is realized by changing the lubricant into fine liquid drops through compressed air, so that the fine liquid drops are more uniformly distributed on the fluffy aramid pulp. According to the embodiment of the invention, spraying is performed through a conical nozzle, the aperture of the nozzle is preferably 2-7 mm, and the flow range can be 1-20L/min; the injection angle is 15-65 deg. The lubricant of the embodiment of the invention has the viscosity of less than or equal to 100 mPas (at 25 ℃), and the atomization effect is easily affected by the excessive viscosity.
After modification treatment, a deposition layer with a certain thickness exists on the surface of the obtained aramid pulp, a uniform isolation layer is formed on the surface of the aramid pulp, and the surface of the aramid pulp is further functionalized through grafting reaction of a silane coupling agent, so that the subsequent rubber reinforcement and other applications are facilitated.
The invention provides an aramid pulp pre-dispersion, which is obtained by premixing modified aramid pulp obtained by the modification treatment method with a rubber matrix and then carrying out a molding process.
In the embodiment of the invention, the modified aramid pulp (53-77 parts by mass) and 20-40 parts by mass of rubber matrix are premixed on an open mill, and 3-7 parts by mass of plasticizer is preferably added after rubber is wrapped; after premixing, the mixture is further mixed and dispersed in a double screw, and the preparation of the aramid pulp pre-dispersion is completed through extrusion, granulation and packaging.
The rubber matrix is an elastomer matrix, wherein modified aramid pulp short fibers are dispersed in the elastomer matrix; the rubber matrix can be one or more selected from Natural Rubber (NR), nitrile Butadiene Rubber (NBR), chloroprene Rubber (CR) and Ethylene Propylene Diene Monomer (EPDM), and all are commercially available raw rubber products.
The invention preferably adopts a natural rubber matrix; and the content of pure aramid pulp in the pre-dispersion of the aramid pulp is as follows: rubber raw rubber content = 5:100 mass ratio.
In an embodiment of the invention, the aramid pulp pre-dispersion further comprises a plasticizer, preferably stearic acid. The preparation of the aramid pulp pre-dispersion adopts a conventional rubber open mill mixing process, for example, raw rubber is coated on an open mill and plasticated for 3-5 minutes, then modified aramid pulp is added for mixing, timing is started, and mixing is stopped after 15-20 minutes.
The invention provides application of the aramid pulp pre-dispersion as a rubber reinforcing material. In some embodiments of the invention, the aramid pulp pre-dispersion prepares a reinforced natural rubber composite; the preparation raw materials specifically comprise: 100 parts by mass of natural rubber; 20-25 parts by mass of the pre-dispersion of the aramid pulp, and has good strength and fatigue resistance.
In an embodiment of the present invention, the reinforced natural rubber composite material preferably further includes: 1-2 parts by mass of a cross-linking agent (specifically sulfur) and 15-20 parts by mass of white carbon black. The invention is not particularly limited in other components and processing of the reinforced natural rubber composite material, and conventional rubber product additives such as an active agent, an accelerator, an anti-aging agent and the like can be added. In addition, the aramid pulp pre-dispersion can be applied to reinforcement of other rubber products and the like, and has a wide application range.
The invention will now be described in further detail with reference to the following examples, which are described herein to aid in understanding the invention and are not intended to limit the scope of the invention.
The reagents and other raw materials of the embodiment of the invention are commercially available and conventional equipment is adopted. Wherein, the fiber length of the aramid pulp raw material is as follows: 0.85-1.35mm, and specific surface area of 9-15m 2 /g; the dopamine salt is hydrochloride thereof; at 25 ℃, the viscosity of dioctyl oxalate is 13.7 mPas, the viscosity of dioctyl azelate is 15 mPas, the viscosity of dibutyl phthalate is 2516.3 mPas, and the viscosity of dioctyl phthalate is 81.4 mPas; the spraying device is provided with a conical nozzle, the aperture of the nozzle is 2-5 mm, and the spraying angle is 15-65 degrees.
Example 1:
preparing a dopamine salt water solution with the mass concentration of 2.0g/L, adding tris (hydroxymethyl) aminomethane to adjust the pH value of the solution to 8.5, adding 40g of aramid pulp raw material into 0.75L of prepared dopamine salt water solution, stirring and reacting for 4 hours, adding 0.5g of KH550 into the solution, stirring and reacting for 2 hours, taking out the aramid pulp, and drying to obtain the blocky aramid pulp.
In a 400L opening device, 5kg of dried blocky aramid pulp is opened to a fluffy state, wherein the rotating speed of a fly cutter is 2500r/min, the stirring rotation is 50r/min, and the opening time is 5 minutes (the opening process of the following embodiment is the same); 20g of lubricant dibutyl phthalate is sprayed on fluffy aramid pulp in a mist mode, and the aramid pulp is stirred at the same time, so that the modified aramid pulp is obtained.
Premixing modified aramid pulp and 35g of natural rubber matrix on an open mill, adding 3g of stearic acid after rubber wrapping a roller, mixing for 10 minutes, putting the mixture into a double screw for further mixing and dispersing after premixing, extruding, granulating and packaging to prepare the pre-dispersion of the aramid pulp.
Example 2:
preparing a dopamine salt water solution with the mass concentration of 2.0g/L, adding tris (hydroxymethyl) aminomethane to adjust the pH value of the solution to 8.5, adding 35g of aramid pulp raw material into 0.50L of prepared dopamine salt water solution, stirring and reacting for 4 hours, adding 0.5g of KH570 into the solution, stirring and reacting for 2 hours, taking out the aramid pulp, and drying to obtain the blocky aramid pulp.
And opening the dried blocky aramid pulp to a fluffy state in opening equipment, spraying 22g of lubricant dioctyl adipate on the fluffy aramid pulp in a mist mode, and stirring the aramid pulp to obtain the modified aramid pulp.
Premixing the modified aramid pulp and 34.5g of natural rubber matrix on an open mill, adding 7g of stearic acid after rubber wrapping a roller, mixing for 10 minutes, putting the mixture into a double screw for further mixing and dispersing after premixing, extruding, granulating and packaging to finish the preparation of the pre-dispersion of the aramid pulp.
Example 3:
preparing a dopamine salt water solution with the mass concentration of 2.0g/L, adding tris (hydroxymethyl) aminomethane to adjust the pH value of the solution to 8.5, adding 45g of aramid pulp raw material into 1.00L of prepared dopamine salt water solution, stirring and reacting for 4 hours, adding 1.5g of KH560 into the solution, stirring and reacting for 2 hours, taking out the aramid pulp, and drying to obtain the blocky aramid pulp.
And opening the dried blocky aramid pulp to a fluffy state in opening equipment, spraying 17.5g of lubricant dioctylphthalate onto the fluffy aramid pulp in a mist mode, and stirring the aramid pulp to obtain the modified aramid pulp.
Premixing the modified aramid pulp and 28g of natural rubber matrix on an open mill, adding 6g of stearic acid after rubber wrapping a roller, mixing for 10 minutes, putting the mixture into a double screw for further mixing and dispersing after premixing, extruding, granulating and packaging to prepare the pre-dispersion of the aramid pulp.
Example 4:
preparing a dopamine salt water solution with the mass concentration of 2.0g/L, adding tris (hydroxymethyl) aminomethane to adjust the pH value of the solution to 8.5, adding 30g of aramid pulp raw material into 1.0L of prepared dopamine salt water solution, stirring and reacting for 4 hours, adding 1.0g of KH560 into the solution, stirring and reacting for 2 hours, taking out the aramid pulp, and drying to obtain the blocky aramid pulp.
And opening the dried blocky aramid pulp to a fluffy state in opening equipment, spraying 21g of lubricant dioctyl adipate on the fluffy aramid pulp in a mist mode, and stirring the aramid pulp to obtain the modified aramid pulp.
Premixing modified aramid pulp and 40g of nitrile rubber matrix on an open mill, adding 6g of stearic acid after rubber wrapping a roller, mixing for 10 minutes, putting the mixture into a double screw for further mixing and dispersing after premixing, extruding, granulating and packaging to prepare the pre-dispersion of the aramid pulp.
Example 5:
preparing a dopamine salt water solution with the mass concentration of 2.0g/L, adding tris (hydroxymethyl) aminomethane to adjust the pH value of the solution to 8.5, adding 50g of aramid pulp raw material into 1.0L of prepared dopamine salt water solution, stirring and reacting for 4 hours, adding 1.5g of KH570 into the solution, stirring and reacting for 2 hours, taking out the aramid pulp, and drying to obtain the blocky aramid pulp.
And opening the dried blocky aramid pulp to a fluffy state in opening equipment, spraying 21g of lubricant dioctylphthalate onto the fluffy aramid pulp in a mist mode, and stirring the aramid pulp to obtain the modified aramid pulp.
Premixing modified aramid pulp and 20.5g of chloroprene rubber matrix on an open mill, adding 5g of stearic acid after rubber wrapping a roller, mixing for 10 minutes, putting the mixture into a double screw for further mixing and dispersing after premixing, extruding, granulating and packaging to prepare the pre-dispersion of the aramid pulp.
Example 6:
preparing a dopamine salt water solution with the mass concentration of 2.0g/L, adding tris (hydroxymethyl) aminomethane to adjust the pH value of the solution to 8.5, adding 40g of aramid pulp raw material into 0.50L of prepared dopamine salt water solution, stirring and reacting for 4 hours, adding 0.5g of KH550 into the solution, stirring and reacting for 2 hours, taking out the aramid pulp, and drying to obtain the blocky aramid pulp.
And opening the dried blocky aramid pulp to a fluffy state in opening equipment, spraying 23g of lubricant dioctyl azelate on the fluffy aramid pulp in a mist mode, and stirring the aramid pulp to obtain the modified aramid pulp.
Premixing the modified aramid pulp and 28.5g of ethylene propylene diene monomer rubber matrix on an open mill, adding 7g of stearic acid after rubber wrapping a roller, mixing for 10 minutes, putting the mixed materials into a double screw for further mixing and dispersing after premixing, extruding, granulating and packaging to prepare the pre-dispersion of the aramid pulp.
In examples 4-6, specific rubber matrices are as follows: nitrile rubber N220S, acrylonitrile 41%, manufactured by japan synthetic rubber company; chloroprene rubber CR232, chongqing longevity chemical production; ethylene propylene diene monomer 4045 and Jilin petrochemical production.
Comparative example 1
And opening 40g of aramid pulp raw material to a fluffy state in opening equipment, spraying 20g of lubricant dibutyl phthalate on the fluffy aramid pulp in a mist mode, and stirring the aramid pulp to obtain the lubricated aramid pulp.
Premixing the lubricated aramid pulp and 35g of natural rubber matrix on an open mill, adding 3g of stearic acid after rubber wrapping a roller, mixing for 10 minutes, putting the mixture into a double screw for further mixing and dispersing after premixing, extruding, granulating and packaging to prepare the pre-dispersion of the aramid pulp.
Referring to fig. 1 to 3, by comparing the SEM microstructure photograph of the aramid pulp staple fiber raw material (raw material of comparative example 1, untreated) with the aramid pulp treated with the dopamine and silane coupling agent (before lubrication of example 1), the surface of the untreated aramid pulp staple fiber was smooth, the original smooth surface of the aramid pulp staple fiber became rugged after the treatment with the dopamine and silane coupling agent, a deposition layer of a certain thickness was formed, a uniform isolation layer was formed on the surface of the aramid pulp staple fiber, and the surface of the aramid pulp staple fiber was further functionalized by the grafting reaction of the coupling agent.
For evaluation of the dispersion property of the aramid pulp pre-dispersion in the elastomer matrix, the invention adopts a hot pressing film making method as follows, and the content of pure aramid pulp in the aramid pulp pre-dispersion is as follows: rubber raw rubber content = 5:100 parts by mass. In the formula composition of the composite material, the raw rubber of the elastomer is selected from Natural Rubber (NR), chloroprene Rubber (CR), nitrile Butadiene Rubber (NBR) or Ethylene Propylene Diene Monomer (EPDM), and is a commercially available raw rubber product.
The preparation of the composite material adopts a conventional rubber open mill mixing process, raw rubber is coated on an open mill for plasticating for 3 minutes, then the mixing of the aramid pulp pre-dispersion is started, timing is started, the mixing is stopped after 20 minutes, sampling is carried out, and the evaluation of the dispersion performance of the aramid pulp in the aramid pulp pre-dispersion is carried out according to a hot-pressing film-making method as follows.
The hot-pressing film-forming method is that 0.5g of uniformly mixed composite material is randomly sampled, then the composite material is placed between polyester films, and hot-pressed for 2 minutes at 150 ℃ on a hot press, and the pressure is 15MPa. The distribution of the fibers on the surface of the obtained film is observed by naked eyes, and the distribution is classified into the following four grades according to the good or bad of the dispersibility of the fibers:
excellent: the film surface is very uniform, and short fiber spots are not observed;
good: the surface of the film is uniform, a small amount of short fiber spots exist, and the spot size is not more than 0.5mm;
qualified: the surface of the film is not uniform, and has more short fiber spots, and the size is more than 0.5mm and not more than 1.5mm;
very bad: the film surface is very uneven, and has a large number of short fiber spots, and the size is more than 1.5mm.
Examples 1 to 6 and comparative example 1 were compounded with the corresponding rubber raw rubber, respectively, and the dispersion properties of the aramid pulp in the aramid pulp pre-dispersion were evaluated according to the "hot press film-forming method", examples 1, 2,3, 4, 6 were evaluated as "excellent", example 5 was evaluated as "good", and comparative example was evaluated as "poor".
Application example:
the aramid pulp pre-dispersion prepared in examples 1, 2 and 3 and comparative example 1 was added as a reinforcing material to prepare an aramid pulp-natural rubber composite material, which was tested for mechanical properties and fatigue resistance. The aramid pulp-natural rubber composite material is prepared according to the rubber standard formula ratio, and the formula is as follows (mass parts):
natural rubber 100; an aramid pulp pre-dispersion 25; zinc oxide 5; stearic acid 1; accelerator TT 1.5; accelerator M0.5; age resister RD 1.5; 1.5 parts of sulfur; white carbon black (white carbon black VN3, dezakiku limited) 20.
Blank examples without aramid pulp pre-dispersion are prepared according to a rubber standard formula, and mechanical properties and fatigue resistance are tested and compared. The specific performance indexes are as follows:
TABLE 1 Performance index results for the inventive application example
Blank examples Comparative example 1 Example 1 Example 2 Example 3
Tensile Strength/MPa 21.3 20.6 26.7 25.4 24.8
100% stress/MPa 2.31 2.57 2.85 2.73 2.67
Elongation at break/% 542 524 611 587 573
Shore (A) hardness 68 71 70 70 69
Tear strength KN/m 65.8 63.4 75.2 73.5 72.7
Number of fatigue breaks/time of extension 201675 148521 267465 245842 238542
As can be seen from table 1, the mechanical properties and the number of tensile fatigue breaks of the comparative example were reduced compared to the blank example without the aramid pulp added, indicating that the unmodified aramid pulp did not have an enhanced effect in the rubber, mainly because the aramid pulp was not completely dispersed in the rubber, and the undispersed aramid pulp became a stress concentration point in the rubber, reducing various properties of the composite material. The mechanical properties and the stretching fatigue fracture times of the examples 1, 2 and 3 are obviously improved, which shows that the mechanical properties and the fatigue resistance of the composite material can be effectively improved by adding the aramid pulp pre-dispersion.
Compared with the comparative example, it is also demonstrated that the modification treatment of the aramid pulp can significantly improve the dispersibility and interfacial bonding properties of the aramid pulp.
As can be seen from the above examples, the invention adopts the modification treatment of the aramid pulp by using dopamine, silane coupling agent and the like, has simple operation steps and obvious modification effect, further improves the dispersibility of the aramid pulp in rubber, the interfacial adhesion of the aramid pulp and the rubber and the like, and is beneficial to application.
Finally, it should be noted that the specific embodiments described herein are merely illustrative of the spirit of the invention and are not limiting of the invention. Other modifications and additions to the described embodiments and similar alternatives to the described embodiments will be apparent to those skilled in the art, and it is not necessary nor necessary to fully implement the invention. And obvious changes and modifications which come within the spirit of the invention are desired to be protected.

Claims (8)

1. The aramid pulp modification treatment method is characterized by comprising the following steps of:
carrying out surface modification on the aramid pulp short fiber in water by adopting dopamine and silane coupling agent, and drying to obtain blocky aramid pulp;
applying a lubricant after loosening the blocky aramid pulp to obtain modified aramid pulp;
the mass ratio of the dopamine to the silane coupling agent to the aramid pulp is 1-2: 0.5-2: 30-50 parts; the lubricant is selected from one or more of dibutyl phthalate, dioctyl adipate and dioctyl azelate; the viscosity of the lubricant is less than or equal to 100 mPa.s at 25 ℃; the mass ratio of the lubricant to the aramid pulp short fiber is 17.5-23: 30-50 parts; the lubricant is sprayed on the opened aramid pulp in a droplet mist form.
2. The aramid pulp modification treatment method according to claim 1, wherein the silane coupling agent is selected from one or more of KH550, KH560, and KH 570.
3. The aramid pulp modification treatment method according to any one of claims 1 to 2, wherein the spray nozzle has a pore diameter of 2 to 7 mm and a flow rate range of 1 to 20l/min.
4. An aramid pulp pre-dispersion obtained by premixing the modified aramid pulp obtained by the modification treatment method of any one of claims 1 to 3 with a rubber matrix and then molding.
5. The aramid pulp pre-dispersion of claim 4 wherein the rubber matrix is selected from one or more of natural rubber, nitrile rubber, neoprene and ethylene propylene diene rubber.
6. The aramid pulp pre-dispersion of claim 4 or 5 further comprising a plasticizer, wherein the plasticizer is stearic acid.
7. Use of the pre-dispersion of aramid pulp as defined in any one of claims 4 to 6 as a rubber reinforcing material.
8. The use according to claim 7, wherein the pre-dispersion of aramid pulp produces a reinforced natural rubber composite; the preparation raw materials comprise: 100 parts by mass of natural rubber; 20-25 parts by mass of an aramid pulp pre-dispersion; also comprises 1-2 parts by mass of cross-linking agent and 15-20 parts by mass of white carbon black.
CN202311316575.XA 2023-10-12 2023-10-12 Aramid pulp modification treatment method, aramid pulp pre-dispersion and application thereof Pending CN117051591A (en)

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