CN113957561A

CN113957561A - Conductive layer coating method for conductive fibers

Info

Publication number: CN113957561A
Application number: CN202111258779.3A
Authority: CN
Inventors: 丁成; 吕康; 陈军; 吕允辉
Original assignee: Changlong Plastic Technology Suzhou Co ltd
Current assignee: Changlong Plastic Technology Suzhou Co ltd
Priority date: 2021-10-27
Filing date: 2021-10-27
Publication date: 2022-01-21

Abstract

The invention provides a conductive fiber, which comprises a skin layer and a core layer, wherein the skin layer is composed of a non-conductive thermoplastic high polymer, the core layer is composed of a carbon black material or a graphene oxide material or a mixture of graphene oxide and other conductive fillers, the core layer deviates from the center of the skin layer, the outer surface of the skin layer is provided with a near core area, a far core area and a transition area positioned between the near core area and the far core area, and the near core area is formed into a viscous state through physicochemical treatment and coated with a metal coating. The conductive fiber disclosed by the invention has excellent conductivity and anisotropy, not only has the advantages of metal fibers, but also makes up for the defects of high manufacturing cost and poor cohesion of the metal fibers, and also has the advantages of common conductive fibers, and is convenient to manufacture and process.

Description

Conductive layer coating method for conductive fibers

Technical Field

The invention relates to the technical field of high polymer materials, in particular to a coating method of a conductive layer of conductive fibers.

Background

With the development of science and technology, various industries have higher and higher requirements on the conductivity, antistatic property and electromagnetic shielding property of fabrics or clothes, and various proposals have been made on the manufacturing method of conductive fibers. The conductive fibers include various kinds, including metal-based conductive fibers, carbon black-based conductive fibers, conductive polymer-based fibers, and metal compound-based conductive fibers. The conductivity of the conductive fiber prepared by the methods basically meets the requirements of production and living, but also has a plurality of inevitable defects.

For example, the metal-based conductive fiber mainly includes a pure metal wire obtained by a multi-strand drawing, cutting, and drawing method, and a conductive fiber obtained by depositing a metal on the surface of the fiber by vacuum spraying or a chemical electro-coating method so that the fiber has the same conductivity as the metal. The metal conductive fiber made by using the conductive property of metal mainly includes stainless steel fiber, copper fiber and aluminium fiber, and these fibers are excellent in conductive property, heat-resisting and chemical corrosion-resisting, but difficult to manufacture, and its fine monofilament has high cost, poor cohesive force with general fiber and good propertyBlending cannot be homogenized; for example, the utility model patent ZL200720033528 and the utility model patent ZL200720033522 are all made by blending flax cotton yarn or synthetic fiber with metal silk thread. The conductive fiber prepared by the spraying method and the sedimentation method has the fastness which is difficult to meet the requirement of the subsequent production, the plating layer on the surface falls off in the weaving and knitting process and the subsequent process, or the plating layer is easy to dissolve and remove in the dyeing treatment or the refining treatment of the cloth, for example, the invention patent ZL200610032518 discloses a preparation method of the superfine light conductive fiber, and good conductivity is obtained on the fiber by chemical plating metal; patent application 92108939 provides a method for preparing conductive fibers and fabrics by electroplating fibers and fabrics after cleaning; the invention patent ZL02159717 discloses a plant conductive fiber and a preparation method thereof, and a metal coating 6 is coated on the plant fiber by a chemical plating method. The metal conductive fiber has the best conductive performance, and the volume specific resistance can be only 10^-4-10^-5Omega cm. The carbon black series conductive fiber is made by utilizing the conductive property of carbon black, and has a doping type, namely, the carbon black and fiber forming substances are mixed and then spun, and the carbon black forms a continuous phase structure in the fiber to endow the fiber with the conductive property.

At present, most patents produce conductive fibers by the method, firstly, conductive components are dispersed in carrier resin, and the carrier resin is granulated into conductive master batches by a double screw, and then the conductive master batches and fiber-forming high polymers are melted and then are prepared by a conductive spinning assembly and a conductive spinning process. For example, patent application 200710075982 discloses a durable high-performance conductive fiber, which is prepared by dispersing carbon black in a carrier resin by a mixing method, granulating by a twin-screw extruder to obtain conductive master batches, melting the conductive master batches and a fiber-forming high polymer, and then processing by a conductive spinning process through a specially designed trilobal and multilayer conductive spinning assembly; patent application 200610023797, patent application 200510102574, patent ZL200410033773 and patent application 200410017918 each disclose a conductive fiber containing carbon nanotubes; patent ZL200410025182 and patent application 03115681 each disclose a conductive fiber containing a carbon black conductive component. Carbon black or metal compound is used to prepare fiber with excellent conductivity through adsorption coating.

The metal plating method is to treat the surface of the common fiber, and then to deposit the metal on the fiber surface by vacuum spraying or chemical plating method, so that the fiber has the same conductivity as the metal, but the complete coating method adopted in the prior art can cause the conductive fiber not to have anisotropy, the post treatment is too limited, the plating layer on the surface is dropped in the weaving and knitting process and the subsequent process, or the plating layer is easily dissolved and removed in the dyeing treatment or refining treatment of the fabric, and the durable conductivity effect is difficult to achieve.

In view of the above, there is a need for an improved conductive fiber in the prior art to solve the above problems.

Disclosure of Invention

The invention aims to disclose a conductive fiber and a coating method of a conductive layer thereof, which have excellent conductivity and anisotropy, not only have the advantages of metal fibers, but also make up for the defects of high manufacturing cost and poor cohesion of the metal fibers, and simultaneously have the advantages of common conductive fibers, are convenient to manufacture and process, and are suitable for monitoring the sensitivity of a sensor to an electric signal.

In order to achieve the purpose, the invention provides a conductive fiber, which comprises a skin layer and a core layer, wherein the skin layer is made of a non-conductive thermoplastic high polymer, the core layer is made of a carbon black material or a graphene oxide material or a mixture of graphene oxide and other conductive fillers, the core layer deviates from the center of the skin layer, the outer surface of the skin layer is provided with a near core area, a far core area and a transition area positioned between the near core area and the far core area, and the near core area is formed with a viscous state through physicochemical treatment and coated with a metal coating.

As a further improvement of the invention, the eccentric structure of the conductive fiber forms anisotropic visualization on the periphery of the cross section of the conductive fiber at the geometric center through physical and chemical treatment.

As a further improvement of the invention, the thermoplastic high molecular polymer is at least one selected from polyethylene, polypropylene, polyester, PPS and PEEK.

As a further improvement of the invention, the ratio of the surface area of the core layer to the surface area of the skin layer under the cross-sectional area of the conductive fiber is less than 0.3.

As a further improvement of the present invention, the other conductive fillers include, but are not limited to: at least one of carbon nanotubes, expanded graphite, silver nanowires, copper nanowires or silver nanoplates.

As a further improvement of the invention, the core layer is provided with a plurality of core layers, and the core layers are distributed with the center of the skin layer as the center symmetry.

As a further improvement of the invention, the mass ratio of the graphene oxide to other conductive fillers is as follows: 1: 0.1 to 1.

As a further improvement of the present invention, a hollow cavity is provided between the distal core region of the conductive fiber and the core layer.

The invention also discloses a conductive layer coating method of the conductive fiber, which comprises the following steps:

s1, preparing a core layer spinning solution and a skin layer spinning solution, and performing conductive spinning on the obtained core layer spinning solution and the obtained skin layer spinning solution through respective corresponding pipelines to obtain conductive fibers;

s2, heating the core layer in the conductive fiber in an electromagnetic induction heating mode to 20-50 ℃ so that the core area is in a sticky state;

s3, placing the conductive fiber processed by the S2 step in at least one of metal ion solution or silver-containing solution, copper-containing solution and nickel-containing solution for chemical deposition, wherein the chemical deposition is processed by ultrasonic with the ultrasonic power of 5-50W/L;

and step S4, repeating the step S2 and the step S3 for several times in sequence, wherein the deposition time is 30-60min, and finally performing heat treatment.

As a further improvement of the invention, the metal ion solution is an aqueous solution of at least one of silver nitrate, silver fluoride, silver trifluoroacetylacetonate, silver acetate, silver ammonia solution, nickel sulfate, nickel chloride, nickel sulfamate and nickel bromide.

As a further improvement of the present invention, in the step S2, the core layer is heated and the moisture on the surface of the skin layer is rapidly dried.

As a further improvement of the present invention, in the step S4, before the heat treatment process, the conductive fiber needs to be cleaned and dried, and the cleaning manner is to place the conductive fiber with the plating layer in a mixed solution of deionized water and dimethyl sulfoxide to clean under an ultrasonic condition with a power of 40W/L, so as to remove the metal coating coated on the conductive fiber in the transition region and the far-core region.

Compared with the prior art, the invention has the beneficial effects that:

(1) the utility model provides a conductive fiber, the conductive fiber of core type structure includes cortex and sandwich layer, the cortex adopts non-conductive thermoplasticity high molecular polymer, the sandwich layer adopts carbon black material or graphene oxide material or the mixture of graphene oxide and other electrically conductive filler, when making the sandwich layer have excellent electric conductivity, carbon black material or graphene oxide material or the mixture of graphene oxide and other electrically conductive filler can also regard as the heating heat source, through electromagnetic induction heating, can make the sandwich layer heat up fast, can accurate control heating temperature, the cortex adopts non-conductive thermoplasticity high molecular polymer, electromagnetic heating is insensitive, temperature variation is less, can play the effect of protection to inside sandwich layer. The centre of a circle department setting of the skew cortex of sandwich layer, make the surface of cortex be formed with near-core region, far away the core region, and the transition region, when the carbon-based material of electromagnetic induction heating, through the accurate control to heating temperature, can form the influence of different degree to the cortex, the effective temperature of near-core region is the highest, and descend progressively to far away the core region through filtering area, through surface treatment, make near-core region form and glue the attitude, and far away core region and transition region are in the smooth state, the cortex of gluing the attitude carries out metal coating more easily, and the adhesive force is high, the coating on surface is difficult to drop in weaving process and process thereafter, or the coating is difficult to be dissolved and is detached when dyeing treatment or refining treatment of cloth, can reach lasting electrically conductive effect.

(2) The eccentric structure of the conductive fiber is partially plated with a metal coating through physicochemical treatment to realize the anisotropic visualization of the periphery of the cross section of the conductive fiber by using a geometric center, so that the conductive fiber has plasticity in the later-stage manufacturing treatment and is not limited too much.

(3) The thermoplastic high molecular polymer adopts at least one selected from polyethylene, polypropylene, polyester, PPS and PEEK to form a polymer layer, active groups on the polymer layer can be used as reaction base points to deposit metal copper, silver, nickel and cadmium, the damage to a fiber structure by methods such as etching and the like can be avoided, the damage degree to fibrils is low, and the high mechanical property of the whole conductive fiber is ensured.

(4) The ratio of the surface area of the core layer to the surface area of the skin layer under the cross-sectional area of the conductive fiber is less than 0.3, so that the basic conductivity of the conductive fiber is ensured, the weakness of the core layer can be reduced, the heating area is easy to control, the overlarge heating area is avoided, the accuracy and controllability of a later-stage coating process are improved, and the fiber structure is ensured not to be easily damaged.

(5) A hollow cavity is arranged between the skin layer and the core layer of the conductive fiber. The cross-sectional area of the hollow cavity accounts for 10% -30% of the total area, and the arrangement of the hollow structure enables the heat-insulating property of the skin layer to the core layer to be improved. The hollow cavity is arranged between the core layer and the skin layer, so that the crimping rate and the crimping stability of the conductive fiber are higher, the bulkiness and the hand feeling of the obtained conductive fiber are better, meanwhile, when the core layer is subjected to electromagnetic induction heating, the heat of the core layer cannot be directly conducted to the skin layer from the inside, and the hollow cavity is used as a heat preservation cavity and provides a stable subsequent heat source for the metal coating; the cross section of the conductive fiber is of a special-shaped structure, the central points of the skin layer and the core layer are not overlapped, the conductive fiber is endowed with three-dimensional curling performance by designing an eccentric structural characteristic, the fluffiness of the fiber is improved, the conductive fiber is curled in a three-dimensional space, the obtained fiber is good in fluffiness, soft and smooth in hand feeling, high in elastic recovery rate, good in curling stability and good in dyeing performance.

(6) A conductive layer coating method of conductive fiber comprises preparing a core layer spinning solution and a skin layer spinning solution, respectively passing the obtained core layer spinning solution and skin layer spinning solution through respective corresponding pipelines, conducting spinning to obtain conductive fiber, heating the core layer in the conductive fiber in an electromagnetic induction heating mode, locally heating to 20-50 ℃, performing surface treatment to make the near-core area become sticky, putting the treated conductive fiber into at least one of a metal ion solution or a silver-containing solution, a copper-containing solution and a nickel-containing solution for chemical deposition, performing ultrasonic treatment with ultrasonic power of 5-50W/L, and making metal components enter the deep part of the skin layer under the double conditions of expansion of the surface of the skin layer and ultrasonic treatment by proper heating, thereby improving the bonding force between the metal coating and the skin layer in a coating process, can quickly form a compact metal coating, and ensures the high conductivity of the conductive fiber.

(7) The plating layer is repeatedly heated by electromagnetic induction and treated by ultrasonic for a plurality of times, so that the deposition efficiency and the combination degree of metal can be improved, a metal coating with higher adhesiveness is formed on the surface of the cortex of the conductive fiber in a near-core area, the conductivity and the surface performance of the metal coating are ensured, the conductive fiber needs to be cleaned and thermally treated after the plating layer is finished, the conductive fiber with the plating layer is cleaned by placing the conductive fiber in a mixed solution of deionized water and dimethyl sulfoxide under the ultrasonic condition of 40W/L power, the cleaning aims to remove the phenomenon that a small amount of metal substances are adhered on the exposed outer surface of the cortex and the core layer and the residual metal salt solution on the outer surface of the conductive fiber, the phenomenon that the conductive fiber is integrally provided with the metal coating with uneven thickness during thermal treatment is avoided, and the anisotropy of the conductive fiber can be more prominent after the cleaning treatment, the metal coating on the conductive fiber can be slightly bent under the static or electrified condition, and is suitable for monitoring the sensitivity of the sensor to an electric signal. Finally, silver particles, copper ions or nickel particles accumulated near the core layer are melted to form a continuous phase through heat treatment, so that the conductivity and the surface performance of the metal coating are further improved.

Drawings

FIG. 1 is a cross-sectional view of a conductive fiber of the present invention;

fig. 2 is a process flow chart of a method for coating a conductive layer of a conductive fiber according to the present invention.

In the figure: 1. a skin layer; 2. a core layer; 3. a near-core region; 4. a distal region; 5. a transition zone; 6. and (3) coating the metal.

Detailed Description

The present invention is described in detail with reference to the embodiments shown in the drawings, but it should be understood that these embodiments are not intended to limit the present invention, and those skilled in the art should understand that functional, methodological, or structural equivalents or substitutions made by these embodiments are within the scope of the present invention.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

In the description of the present application, it is to be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientation or positional relationship indicated in the drawings for convenience in describing the present application and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and are not to be considered limiting of the scope of the present application. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the invention, the meaning of "a plurality" is two or more unless otherwise specified.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art through specific situations.

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Please refer to fig. 1 to 2, which illustrate an embodiment of a conductive fiber according to the present invention.

Referring to fig. 1, in this embodiment, a conductive fiber includes a skin layer 1 and a core layer 2, the skin layer 1 is made of a non-conductive thermoplastic high molecular polymer, the core layer 2 is made of a carbon black material or a graphene oxide material or a mixture of graphene oxide and other conductive fillers, the core layer 2 deviates from the center of the skin layer 1, a near core region 3, a far core region 4 and a transition region 5 located between the near core region 3 and the far core region 4 are formed on the outer surface of the skin layer 1, and the near core region 3 is formed with a sticky state through a physicochemical treatment and is coated with a metal coating 6. The core-offset structure of the conductive fiber forms anisotropic visualization on the periphery of the cross section of the conductive fiber by a geometric center through physical and chemical treatment. The thermoplastic high molecular polymer is at least one selected from polyethylene, polypropylene, polyester, PPS and PEEK. The ratio of the surface area of the core layer 2 to the surface area of the skin layer 1 under the cross-sectional area of the conductive fiber is less than 0.3. Other conductive fillers include, but are not limited to: at least one of carbon nanotubes, expanded graphite, silver nanowires, copper nanowires or silver nanoplates. The core layer 2 has a plurality of core layers, and is distributed with the center of the skin layer 1 as the center symmetry. The mass ratio of the graphene oxide to other conductive fillers is as follows: 1: 0.1 to 1.

It should be noted that, in the embodiment of the conductive fiber, the conductive fiber with the eccentric core structure includes a sheath layer 1 and a core layer 2, the sheath layer 1 is made of a non-conductive thermoplastic high molecular polymer, the thermoplastic high molecular polymer may be at least one selected from polyethylene, polypropylene, polyester, PPS, and PEEK, preferably, polyethylene or polyester is selected as a material of the sheath layer, and the core layer 2 is preferably made of a carbon black material, a graphene oxide material, or a mixture of graphene oxide and other conductive fillers, so that the core layer 2 has excellent conductivity, and at the same time, the carbon black material, the graphene oxide material, or the mixture of graphene oxide and other conductive fillers may also be used as a heating source, by electromagnetic induction heating, the core layer 2 can be rapidly heated, the heating temperature can be accurately controlled, and the sheath layer 1 is made of a non-conductive thermoplastic high molecular polymer, electromagnetic heating is insensitive, temperature change is little, can play the effect of protection to inside sandwich layer 2. The core layer 2 is arranged at the position deviating from the center of the skin layer 1, so that the outer surface of the skin layer 1 is provided with a near core area 3, a far core area 4 and a transition area 5, when the carbon-based material is heated by electromagnetic induction, the skin layer 1 can be influenced by different degrees through the accurate control of the heating temperature, a temperature gradient distribution line gradually decreased from the near core area 3 to the far core area 4 is formed, the effective temperature of the near core area 3 is the highest, the temperature of the near core area 3 is relatively close to that of the core area 3, the influence change of the temperature of the far core area 4 is the smallest, the far core area 4 gradually decreases towards the far core area 4 through the transition area 5, the near core area 3 is enabled to form a sticky state through specific easy surface treatment, the far core area 4 and the transition area 5 are in a smooth state, the skin layer 1 in the sticky state is easier to carry out a metal coating, the binding force is high, and the metal coating 6 plated on the surface is not easy to fall off in a weaving process and a subsequent process, alternatively, the metal coating layer 6 plated during the dyeing treatment or the refining treatment of the fabric is hardly dissolved and removed, and a durable conductive effect can be obtained.

Specifically, the eccentric structure of the conductive fiber is subjected to partial metal coating 6 through physical and chemical treatment to realize anisotropic visualization of the periphery of the cross section of the conductive fiber by using a geometric center, so that the conductive fiber has plasticity in the later manufacturing treatment and is not limited too much. The thermoplastic high molecular polymer adopts at least one selected from polyethylene, polypropylene, polyester, PPS and PEEK to form a polymer layer, active groups on the polymer layer can be used as reaction base points to deposit metal copper, silver, nickel and cadmium, the damage to a fiber structure by methods such as etching and the like can be avoided, the damage degree to fibrils is low, and the high mechanical property of the whole conductive fiber is ensured. The ratio of the surface area of the core layer 2 to the surface area of the skin layer 1 under the cross-sectional area of the conductive fiber is less than 0.3, so that the basic conductivity of the conductive fiber is ensured, the weakness of the core layer can be reduced, the heating area is easy to control, the overlarge heating area is avoided, the accuracy and controllability of a later-stage coating process are improved, and the fiber structure is ensured not to be easily damaged.

More specifically, a hollow cavity is arranged between the skin layer 1 and the core layer 2 of the conductive fiber. The cross section area of the hollow cavity accounts for 10% -30% of the total area, and the arrangement of the hollow structure enables the heat insulation performance of the skin layer 1 to the core layer 2 to be improved. The hollow cavity is arranged between the core layer 2 and the skin layer 1, so that the crimping rate and the crimping stability of the conductive fiber are higher, the bulkiness and the hand feeling of the obtained conductive fiber are better, meanwhile, when the core layer is subjected to electromagnetic induction heating, the heat of the core layer 2 cannot be directly conducted to the skin layer 1 from the inside, and the hollow cavity is used as a heat preservation cavity and provides a stable subsequent heat source for the metal coating 6; the cross section of the conductive fiber is of a special-shaped structure, the central points of the skin layer 1 and the core layer 2 are not overlapped, the conductive fiber is endowed with three-dimensional curling performance by designing an eccentric structural characteristic, the fluffiness of the fiber is improved, the conductive fiber is curled in a three-dimensional space, the obtained fiber is good in bulkiness, soft and smooth in hand feeling, high in elastic recovery rate and good in curling stability, and has good dyeing performance.

Referring to fig. 2, the invention also discloses a coating method of the conductive layer of the conductive fiber, which comprises the following steps: s1, preparing a core layer 2 spinning solution and a skin layer 1 spinning solution, and conducting spinning on the obtained core layer 2 spinning solution and the obtained skin layer 1 spinning solution through corresponding pipelines respectively to obtain conductive fibers; s2, heating the core layer 2 in the conductive fiber in an electromagnetic induction heating mode to 20-50 ℃ so that the near-core area 3 is in a sticky state; s3, placing the conductive fiber processed by the S2 step in at least one of metal ion solution or silver-containing solution, copper-containing solution and nickel-containing solution for chemical deposition, wherein the chemical deposition adopts ultrasonic treatment with the ultrasonic power of 5-50W/L; and step S4, repeating the step S2 and the step S3 for several times in sequence, wherein the deposition time is 30-60min, and finally performing heat treatment. The metal ion solution is at least one aqueous solution of silver nitrate, silver fluoride, silver trifluoroacetylacetonate, silver acetate, silver ammonia solution, nickel sulfate, nickel chloride, nickel sulfamate and nickel bromide. In the step S2, the core layer 2 is heated and the moisture on the surface of the skin layer 1 is rapidly dried.

It should be noted that the invention also discloses a conductive layer coating method of conductive fiber, which comprises preparing a core layer 2 spinning solution and a skin layer 1 spinning solution, respectively passing the obtained core layer 2 spinning solution and skin layer 1 spinning solution through respective corresponding pipelines, conducting spinning to obtain conductive fiber, heating the core layer 2 in the conductive fiber in an electromagnetic induction heating mode, locally heating to 20-50 ℃, performing surface treatment to make the near-core area 3 in a sticky state, placing the treated conductive fiber in at least one of a metal ion solution or a silver-containing solution, a copper-containing solution and a nickel-containing solution for chemical deposition, performing ultrasonic treatment with ultrasonic power of 5-50W/L, making metal components enter the deep part of the skin layer 1 under the double conditions of expansion and ultrasonic treatment of the skin layer 1 surface by proper heating, and improving the binding force of the metal coating 6 and the skin layer 1 in the plating process, the compact metal coating 6 can be quickly formed, and the high conductivity of the conductive fiber is ensured. The coating is repeatedly heated and ultrasonically treated for a plurality of times, so that the time range of ultrasonic treatment is ensured to be 20-30min, metal silver ions or metal nickel ions are uniformly bonded on the surface of the near-core area 3 of the cortex layer 1, meanwhile, after a metal film is formed and attached, the metal coating 6 is carried out again, the compactness of the metal ion layer is ensured, the deposition efficiency and the combination degree of metal can be improved, the metal coating 6 with high adhesiveness is formed on the surface of the cortex layer 1 of the conductive fiber in the near-core area 3, the conductivity and the surface performance of the metal coating 6 are ensured, finally, silver particles, copper ions or nickel particles accumulated in the near-core area 2 are melted to form a continuous phase through heat treatment, and the conductivity and the surface performance of the metal coating 6 are further improved.

According to the method of the invention, in step S3, the metal ion solution is an aqueous solution of at least one of silver nitrate, silver fluoride, silver trifluoroacetylacetone, silver acetate, silver ammonia solution, nickel sulfate, nickel chloride, nickel sulfamate and nickel bromide, wherein the concentration of silver ions in the silver salt solution is 0.2-0.3mol/L, the concentration of nickel ions in the nickel salt solution is 0.08-0.09mol/L, preferably, the first metal ion solution is an aqueous solution of silver fluoride and/or nickel chloride, and the anion radius of the silver fluoride and nickel chloride is smaller, so that the silver fluoride and nickel chloride can be better supported on the polymer layer on the surface of the conductive fiber, and the conductivity of the conductive fiber can be significantly improved.

According to the method of the present invention, in step S3, the ultrasonic treatment conditions may be various conditions in the art, and preferably include: the temperature is 20-50 ℃, and more preferably 30-40 ℃; the ultrasonic power is 5-50W/L, and more preferably 20-40W/L; the time is 30-60min, more preferably 30-40 min. The polymer of the outer layer of the conductive fiber is subjected to metal ion adsorption treatment under the ultrasonic condition, so that metal ions can be better loaded on the polymer layer on the surface of the conductive fiber, and the conductivity of the conductive fiber is further remarkably improved. It should be noted that, when carrying out repeated cladding process, need to ensure that the temperature of metal salt solution is less than the required process temperature 2-3 degrees of cladding, through electromagnetic induction heating, when heating up core layer 2 gradually, cortex 1 and metal salt solution direct contact's within range can produce local temperature compensation, has guaranteed the process demand of cortex 1 deposit metal ion.

It should be noted that, the electromagnetic induction heating and the ultrasonic treatment of the coating are repeated for several times, which can improve the deposition efficiency and the bonding degree of the metal, ensure that the surface of the cortex of the conductive fiber forms the metal coating 6 with higher adhesiveness in the near-core area 3, ensure the conductivity and the surface performance of the metal coating 6, after the coating is finished, the conductive fiber needs to be cleaned and thermally treated, the cleaning mode is that the conductive fiber with the coating is placed in the mixed solution of deionized water and dimethyl sulfoxide to be cleaned under the ultrasonic condition of 40W/L power, the cleaning aims to remove the phenomenon that a small amount of metal substances are adhered on the exposed outer surfaces of the cortex 1 and the core layer 2, and the residual metal salt solution on the outer surface of the conductive fiber, so as to avoid that the conductive fiber is integrally provided with the metal coating 6 with uneven thickness during the thermal treatment, the anisotropy of the conductive fiber can be more prominent, and the metal coating 6 on the conductive fiber can be slightly bent under the static or electrified condition, so that the sensor is suitable for monitoring the sensitivity of the sensor to an electric signal. Finally, silver particles, copper ions or nickel particles accumulated near the core layer 3 are melted to form a continuous phase through heat treatment, so that the conductivity and the surface performance of the metal coating 6 are further improved.

After cleaning, under the protection of nitrogen gas, heat treatment is carried out for 20min at 200 ℃, and the preparation of the conductive fiber with high conductivity is completed. The conditions of the heat treatment may be various heat treatment conditions in the art, and preferably, the conditions of the heat treatment are preferably 200-300 ℃; the time is preferably 30-40 min. The heat treatment under the above-described preferred conditions can further improve the adhesiveness of the conductive fiber obtained. According to the method of the present invention, an inert atmosphere is used to provide heat treatment protection, for example, from at least one of nitrogen, neon, and helium.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. The conductive fiber comprises a skin layer and a core layer, and is characterized in that the skin layer is made of a non-conductive thermoplastic high polymer, the core layer is made of a carbon black material, a graphene oxide material or a mixture of graphene oxide and other conductive fillers, the core layer deviates from the center of the skin layer, a near core area, a far core area and a transition area located between the near core area and the far core area are formed on the outer surface of the skin layer, and the near core area is formed in a sticky state through physicochemical treatment and coated with a metal coating.

2. The conductive fiber according to claim 1, wherein the core-offset structure of the conductive fiber is formed by physical and chemical treatment to make anisotropic visualization on the periphery of the cross section of the conductive fiber at the geometric center.

3. The conductive fiber of claim 1, wherein the thermoplastic polymer is at least one selected from the group consisting of polyethylene, polypropylene, polyester, PPS, and PEEK.

4. The conductive fiber of claim 1, wherein the ratio of the surface area of the core layer to the surface area of the sheath layer is less than 0.3.

5. The conductive fiber of claim 1, wherein said other conductive fillers include, but are not limited to: at least one of carbon nanotubes, expanded graphite, silver nanowires, copper nanowires or silver nanoplates.

6. The conductive fiber as claimed in claim 4, wherein said core layer has a plurality of core layers and is arranged with the center of said skin layer as a central symmetry.

7. The conductive fiber according to claim 1, wherein the mass ratio of the graphene oxide to the other conductive fillers is: 1: 0.1 to 1.

8. The method of claim 1, comprising the steps of:

9. The method of claim 8, wherein the metal ion solution is an aqueous solution of at least one of silver nitrate, silver fluoride, silver trifluoroacetylacetonate, silver acetate, silver ammonia solution, nickel sulfate, nickel chloride, nickel sulfamate, and nickel bromide.

10. The method as claimed in claim 8, wherein the step S2 is performed by heating the core layer and rapidly drying the moisture on the surface of the skin layer.