阅读说明：本技术 一种高强度导电芳纶纤维芯材及其成型工艺 (High-strength conductive aramid fiber core material and forming process thereof ) 是由 安丛举 于 2021-01-13 设计创作，主要内容包括：本发明提供一种高强度导电芳纶纤维芯材及其成型工艺,涉及线材制造领域,用于解决目前线缆芯的热形变严重问题。本发明所提供的芳纶纤维在室温下拉伸强度相比传统对位芳纶提高了15％,且拥有更好的耐高温性、和热形变性。本发明明显区别于传统芳纶的表面改性,创新之处在于用杂环二胺改性碳纳米管,之后利用接枝在碳纳米管表面的氨基(—NH-2)与芳纶(聚对苯二甲酰对苯二胺)原材料中对酰胺(—CONH—)进行聚合反应,生成具有杂环结构的杂环芳纶,石墨烯一方面为机械性能提供了有力的支撑,此外还为芳纶提供了一定的导电性。最后利用纺丝技术将其制成聚酯包覆的线芯材料。本发明具有较高的现实意义和应用价值。(The invention provides a high-strength conductive aramid fiber core material and a forming process thereof, relates to the field of wire manufacturing, and is used for solving the problem of the existing cableThe thermal deformation of the core is a serious problem. Compared with the traditional para-aramid fiber, the tensile strength of the aramid fiber at room temperature provided by the invention is improved by 15%, and the aramid fiber has better high temperature resistance and thermal deformation resistance. The invention is obviously different from the surface modification of the traditional aramid fiber, and has the innovation that the carbon nano tube is modified by heterocyclic diamine, and then the amino (-NH) grafted on the surface of the carbon nano tube is utilized 2 ) The graphene and aramid fiber are subjected to polymerization reaction with para-amide (-CONH-) in an aramid fiber (poly-p-phenylene terephthalamide) raw material to generate heterocyclic aramid fiber with a heterocyclic ring structure, and on one hand, the graphene provides powerful support for mechanical properties and also provides certain conductivity for the aramid fiber. Finally, the polyester-coated wire core material is prepared by using a spinning technology. The invention has higher practical significance and application value.)

1. A high-strength conductive aramid fiber core material and a forming process thereof are characterized in that the preparation comprises the following steps:

s1: synthesizing a heterocyclic diamine modified carbon nanotube;

s2: synthesizing carbon nano tube modified heterocyclic aramid spinning solution by using p-phenylenediamine, p-phenylenediamine and aminated carbon nano tubes;

s3: and preparing the polyester-coated aramid fiber composite core material by using a coaxial wet-process wire drawing method.

2. The high-strength conductive aramid fiber core material and the molding process thereof according to claim 1, wherein the carbon nanotubes are multi-walled carbon nanotubes (MWNTs), and the specific modification manner is as follows: firstly, adding MWNTs into nitric acid for ultrasonic treatment, then filtering, and then drying;

b adding the acidified carbon nano tube into thionyl chloride (SOCl)₂) Mixing and refluxing;

c finally, adding dropwise 2- (4-aminophenyl) -5-aminobenzimidazole (PABZ) with stirring to obtain the amino functionalized MWNTs.

3. The high-strength conductive aramid fiber core material and the molding process thereof as claimed in claim 1, wherein the molar ratio of p-phenylene terephthalamide, p-phenylene diamine, and aminated carbon nanotube is 4: 2-3: 1-2.

4. The high-strength conductive aramid fiber core material and the molding process thereof as claimed in claim 1, wherein the polyester is polyphenyl ester, and the weight ratio of the polyester-coated aramid fiber composite core material is polyester 1: 5-10 parts of carbon nanotube modified hybrid aramid fiber.

5. The high-strength conductive aramid fiber core material and the molding process thereof as claimed in claim 1, wherein the diameter of the polyester-coated aramid fiber composite core material is 0.5-1 mm.

6. The high-strength conductive aramid fiber core material and the molding process thereof as claimed in claim 2, wherein the MWNTs have a diameter of 5 to 20nm and an aspect ratio of 50 to 200.

7. The high-strength conductive aramid fiber core material and the molding process thereof as claimed in claim 2, wherein the amino functionalized MWNTs have an organic content of 15-25% of the total weight.

Technical Field

The invention belongs to the technical field of wires, relates to preparation of high-strength conductive fibers, and particularly relates to a high-strength conductive aramid fiber core material and a forming process thereof.

Background

The electric wire and cable is an indispensable basic equipment for data transmission, electric energy transmission and manufacturing of various electric appliances, instruments, vehicles and production equipment and realizing electromagnetic energy conversion, and is like blood vessels and nerves of national economy. Especially high voltage cables for long-distance transmission are necessary ways to achieve the goal of national great strategy. However, in practical application, we can often find that the cable between two towers sags after a period of time, on one hand, the cable has a creep phenomenon due to the large span of the two towers and the dead weight, and on the other hand, the current in the power transmission line is subjected to the resistance action of the cable to convert the electric energy into heat energy to be released, so that the irreversible thermal deformation of the cable is further promoted. This phenomenon may cause unsafe risks, such as electric shock and fire.

At present, the core material of the large-scale remote power transmission cable is made of metal, most commonly copper, aluminum or copper-aluminum alloy, alloy steel and the like, but the metal material has high density and high cost although having strong mechanical property, and still is not the most suitable core material to a certain extent, so the aramid fiber is introduced by the invention aiming at solving the problems existing in the core material of the current cable. Aramid fiber and composite materials thereof are important directions for the development of advanced novel materials, have a series of excellent performances such as high strength, high specific modulus, low density, good designability, corrosion resistance, fatigue resistance and the like, can be used as a heat-proof and corrosion-proof functional material, and have no substitutable position in the fields of aerospace, weaponry, rail transit, electric automobiles, high-end manufacturing industry and the like, particularly in structural lightweight. High crystallinity and high orientation are the basis for the excellent performance of rigid chain aramid fibers. However, although high crystallinity and high orientation are advantageous for improving the tensile strength, they are often disadvantageous for improving the toughness. Therefore, it is necessary to develop functional polymer fibers with high strength and high toughness to meet the requirements of the safety and high strength of the core material of the cable. The patent CN102839444B prepares a black para-aramid fiber material, and the same patent uses multi-wall carbon nano-tubes as raw materials, and the multi-wall carbon nano-tubes are directly used for modifying poly-p-phenylene terephthalamide after being treated by concentrated sulfuric acid, and form modified aramid fibers through wet spinning, and the method damages the mechanical properties of the para-aramid fibers. The aramid fiber has high crystallinity and orientation, and groups on the chain are very stable and are difficult to combine with inorganic or organic materials, so that the occurrence of the inorganic carbon nanotube easily causes the existence of defects among molecular chains, and the mechanical property of the aramid fiber is reduced.

In addition, this patent still obviously is different from other surface modification aramid fiber, and common surface modification aramid fiber is through combining the texture of nanometer scale to the fibre surface, can realize the mechanical interlocking between fibre and the base member, improves the adhesive force of fibre reinforced composite structure. According to the invention, the tensile strength is improved by enhancing the interaction between the fiber matrix and the nano filler molecules, and meanwhile, the heterocyclic structure containing amino is introduced, so that the heterocyclic aramid fiber is formed in the polymerization process of the aramid fiber, and the molecular structure of the heterocyclic aramid fiber is more complex, so that the heterocyclic aramid fiber has more excellent mechanical properties, has excellent properties in the aspects of high temperature resistance, impact resistance, wear resistance, wave transmission and the like, and is more favorable for compounding the fiber and the resin, thereby being expected to replace the traditional core material at present.

Disclosure of Invention

It is a first object of the present invention to provide a modified carbon nanotube.

The second purpose of the invention is to provide a high-strength conductive aramid fiber spinning solution.

The third purpose of the invention is to provide a forming process of the high-strength conductive aramid fiber core material.

In order to achieve the first object, the present invention provides a modified carbon nanotube, which comprises the following steps:

s1, adding 10g MWNTs into 100ml nitric acid, performing ultrasonic treatment for 30min, refluxing at 90 ℃ for 30min, centrifuging for many times until the pH value is 7, filtering with a polyester film, and drying at 90 ℃ to obtain the acidified MWNTs.

S2: to enhance the reactivity of the groups, acid chloride functionalized MWNTs were obtained. In SOCl₂Adding acidified MWNTs, and refluxing at 90 deg.C for 20min to convert carboxyl group on surface of MWNTs into acid chloride group.

S3: the acid chloride functionalized MWNTs and PABZ were dispersed/dissolved in N, N Dimethylformamide (DMF), respectively, and DMF dissolved with PABZ was slowly added to the acid chloride functionalized MWNTs under stirring, followed by reaction in an oil bath at 60 ℃ for 10 hours. And centrifuging for many times, and drying to obtain the MWNTs with functionalized amino groups.

Through amination treatment of MWNTs, a plurality of amino groups are grafted on the surface of the MWNTs, and meanwhile, aromatic rings exist in chain segments of the MWNTs, so that amide groups (-CONH-) of terephthalic acid amide serving as raw materials in the aramid fiber polymerization process are subjected to polymerization reaction with amino groups on the surfaces of p-phenylenediamine and MWNTs to generate the aramid fiber with a heterocyclic ring structure.

In order to achieve the second object, the invention provides a high-strength conductive aramid fiber, which is prepared by the following steps:

dissolving a proper amount of p-phenylenediamine and aminated MWNTs in a mixed solvent of dimethylacetamide (DMAc)/LiCl, adding a certain amount of terephthaloyl chloride into the solution in an ice water bath and a nitrogen atmosphere for slow reaction, and filtering and degassing to obtain a copolyamide spinning stock solution.

In order to achieve the third object, the invention provides a high-strength conductive aramid fiber core material forming process, which comprises the following steps:

and (2) preparing the polyester-coated aramid fiber by one step through an improved wet spinning technology under the condition that the intrinsic viscosities of the spinning stock solution and the polyphenyl ester solution are 16.9-17.1 and 25 respectively, carrying out hot drawing on the composite fiber at the temperature of 280 ℃, fixing the drawn fiber at the temperature of 400 ℃ after drawing, and carrying out annealing treatment on the drawn fiber to finally obtain the high-strength conductive aramid fiber core material.

The wet spinning technology mentioned above is to use the principle of coaxial spinning, the spinning channel is divided into a shell-core two-part structure, i.e. the core material is aramid fiber, the shell layer is polyester coating layer, and the thickness is directly related to the size of the die of the spinning opening.

In order to enhance the tensile strength of the core material of the wire, the invention also relates to a method for combining 30-100 strands of high-strength conductive aramid fiber core material into one strand and twisting the polyester material on the outer layer so as to meet the actual requirement of the current wire core.

The invention has the beneficial effects that:

1. the modified MWNTs can have better compatibility with fibers, and are firmly limited in molecular chains through the combination of chemical bonds, so that the modified MWNTs are fundamentally different from the traditional surface modification or direct physical mixing, and can bear larger load when the fibers receive the stretching action.

2. Due to the addition of MWNTs and heterocycles, the fiber surface has better affinity, and the polyester material is coated outside the fiber surface, so that on one hand, the fiber material can absorb shear force from the transverse direction to improve the toughness of the material, and on the other hand, the polyphenyl ester can bear high temperature higher than 300 ℃, thereby further improving the heat resistance of the fiber material

The invention provides a novel modified aramid composite material which can be applied to the field of linear materials, and can also be applied to the field of plates and even films.

Drawings

FIG. 1 is a schematic cross-sectional view of a high-strength conductive aramid fiber core material

Detailed Description

Example 1

S1, adding 10g MWNTs into 100ml nitric acid, performing ultrasonic treatment for 30min, refluxing at 90 ℃ for 30min, performing centrifugal cleaning for 4 times until the pH value is 7, filtering with a polyester film, and drying at 90 ℃ to obtain the acidified MWNTs.

S2: 100ml of SOCl was taken₂Adding 8g of acidified MWNTs, refluxing for 20min at 90 ℃, centrifuging for multiple times and drying at 100 ℃ to convert carboxyl on the surface of the MWNTs into acyl chloride.

S3: 5g of the acid chloride-functionalized MWNTs and 1g of PABZ were dispersed/dissolved in N, N Dimethylformamide (DMF), respectively, and DMF in which PABZ was dissolved was slowly added to the acid chloride-functionalized MWNTs with stirring, followed by reaction in an oil bath at 60 ℃ for 10 hours. And centrifuging for many times, and drying to obtain the MWNTs with functionalized amino groups.

S4: 5g of p-phenylenediamine and 5g of aminated MWNTs are dissolved in 100ml of dimethylacetamide (DMAc)/LiCl mixed solvent, wherein LiCl accounts for 3 wt% of the DMAC/LiCl solution, 8.4g of terephthaloyl chloride is added into the solution for slow reaction in an ice water bath and nitrogen atmosphere, and the copolyamide spinning solution is obtained through filtration and vacuum degassing.

S5: adjusting the intrinsic viscosity of the spinning solution to 17 respectively, and preparing polyester-coated aramid fibers by using polyphenyl ester dissolved in carbon tetrachloride through an improved wet spinning technology in one step, carrying out thermal drawing on the composite fibers at the temperature of 280 ℃ for 100%, fixing and drawing the fibers at the temperature of 400 ℃ after drawing, and carrying out annealing treatment on the fibers to finally obtain the high-strength conductive aramid fiber core material.

S6: and finally, combining 50 strands of high-strength conductive aramid fiber core materials into one strand, and twisting the polyphenyl ester material on the outer layer so as to meet the actual requirements of the current wire core.

Example 2

S1, adding 10g MWNTs into 100ml nitric acid, performing ultrasonic treatment for 30min, refluxing at 90 ℃ for 30min, performing centrifugal cleaning for 4 times until the pH value is 7, filtering with a polyester film, and drying at 90 ℃ to obtain the acidified MWNTs.

S2: 100ml of SOCl was taken₂Adding 7g of acidified MWNTs, refluxing for 20min at 90 ℃, centrifuging for multiple times and drying at 100 ℃ to convert carboxyl on the surface of the MWNTs into acyl chloride.

S3: 4.5g of acid chloride-functionalized MWNTs and 1g of PABZ were dispersed/dissolved in N, N Dimethylformamide (DMF), respectively, and DMF in which PABZ was dissolved was slowly added to the acid chloride-functionalized MWNTs with stirring, followed by reaction in an oil bath at 60 ℃ for 10 hours. And centrifuging for many times, and drying to obtain the MWNTs with functionalized amino groups.

The steps for preparing the aramid fiber and the composite core were the same as in example 1.

Example 3

S1, adding 10g MWNTs into 100ml nitric acid, performing ultrasonic treatment for 30min, refluxing at 90 ℃ for 30min, performing centrifugal cleaning for 4 times until the pH value is 7, filtering with a polyester film, and drying at 90 ℃ to obtain the acidified MWNTs.

S2: 100ml of SOCl was taken₂6g of acidified MWNTs are added, and the mixture is refluxed at 90 ℃ for 20min, centrifuged for multiple times and dried at 100 ℃ to convert carboxyl groups on the surfaces of the MWNTs into acid chloride groups.

S3: 4g of the acid chloride-functionalized MWNTs and 1g of PABZ were dispersed/dissolved in N, N Dimethylformamide (DMF), respectively, and DMF in which PABZ was dissolved was slowly added to the acid chloride-functionalized MWNTs with stirring, followed by reaction in an oil bath at 60 ℃ for 10 hours. And centrifuging for many times, and drying to obtain the MWNTs with functionalized amino groups.

The steps for preparing the aramid fiber and the composite core were the same as in example 1.

Example 4

Amino-functionalized MWNTs were prepared in the same manner as in example 1, except that:

s4: 5g of p-phenylenediamine and 4g of aminated MWNTs are dissolved in 100ml of dimethylacetamide (DMAc)/LiCl mixed solvent, wherein LiCl accounts for 3 wt% of the DMAC/LiCl solution, 7.8g of terephthaloyl chloride is added into the solution for slow reaction in an ice water bath and nitrogen atmosphere, and the copolyamide spinning solution is obtained through filtration and vacuum degassing.

S5: adjusting the intrinsic viscosity of the spinning solution to 17 respectively, and preparing polyester-coated aramid fibers by using polyphenyl ester dissolved in carbon tetrachloride through an improved wet spinning technology in one step, carrying out thermal drawing on the composite fibers at 290 ℃, fixing and drawing the fibers at 400 ℃ after drawing, and carrying out annealing treatment to obtain the high-strength conductive aramid fiber core material.

Example 5

The amino functionalized MWNTs were the same as in example 1, except that:

s4: 5g of p-phenylenediamine and 3g of aminated MWNTs are dissolved in 100ml of dimethylacetamide (DMAc)/LiCl mixed solvent, wherein LiCl accounts for 3 wt% of the DMAC/LiCl solution, 7.0g of terephthaloyl chloride is added into the solution for slow reaction in an ice water bath and nitrogen atmosphere, and the copolyamide spinning solution is obtained through filtration and vacuum degassing.

S5: adjusting the intrinsic viscosity of the spinning solution to 17 respectively, and preparing polyester-coated aramid fibers by using polyphenyl ester dissolved in carbon tetrachloride through an improved wet spinning technology in one step, carrying out thermal drawing on the composite fibers at the temperature of 300 ℃ for 100%, fixing and drawing the fibers at the temperature of 400 ℃ after drawing, and carrying out annealing treatment to obtain the high-strength conductive aramid fiber core material.

The performance of the high-strength conductive aramid fiber core materials prepared in example 1, example 2, example 3, example 4 and example 5 was tested, and the test results are shown in table 1.

Table 1 performance testing of high strength conductive aramid fiber core material of examples

As can be seen from table 1, the aramid fiber core material provided by the present invention has excellent mechanical properties and good heat resistance. With the increase of the heterocyclic ring content in the modified carbon nanotube (examples 1, 2 and 3), the tensile strength of the fiber is improved continuously, and the deformation amount is smaller. This is because the amino group in the heterocycle is polymerized with terephthaloyl chloride to form a more complex macromolecule (i.e., the formation of the heterocycle aramid), which is strong to mechanical properties due to steric effect and the support effect of the carbon nanotube during the stretching process. Further increases in specific intensity are also strong proofs. In addition, for examples 1, 4 and 5, the mechanical properties showed a slight decrease in reducing the content of the modified carbon nanotubes in the aramid fibers, indicating that the mechanical properties of the aramid fibers were affected by the number of the modified carbon nanotubes and the number of the heterocyclic rings. But the samples in the examples all had a thermal stability of above 300 ℃. Therefore, the high-strength conductive aramid fiber core material provided by the invention can be more beneficial to solving the problem of sagging of the existing cable.

Finally, it should be emphasized that the above-described preferred embodiments of the present invention are merely examples of implementations, rather than limitations, and that many variations and modifications of the invention are possible to those skilled in the art, without departing from the spirit and scope of the invention.