SILVER-PLATED CONDUCTIVE NYLON FIBER AND PREPARATION METHOD THEREOF

Abstract

The invention provides a silver-plated conductive nylon fiber and a preparation method thereof. The method includes: immersing a nylon fiber in an aqueous solution containing a polyphenolic compound at 60 C. to 70 C., adding a water-soluble oxidant into the solution, continuously reacting at 70 C. to 80 C., and obtaining a polyphenol grafted nylon fiber, where the polyphenolic compound contains a catechol group; immersing the polyphenol grafted nylon fiber into a solution containing silver ions at 15 C. to 25 C. for reaction, and raising the temperature to 70 C. to 80 C. for continuous reaction to obtain a surface-activated nylon fiber; and carrying out chemical silver plating treatment on the surface-activated nylon fiber to obtain the silver-plated conductive nylon fiber. The method does not require a heavy metal sensitizer and therefore is non-toxic and environment-friendly, and the fiber strength is maintained.

Claims

1. A method for preparing a silver-plated conductive nylon fiber, comprising steps of: (1) immersing a nylon fiber in an aqueous solution containing a polyphenolic compound at 60 C. to 70 C., adding a water-soluble oxidant into the solution, continuously reacting the resultant reaction solution at 70 C. to 80 C., and obtaining a polyphenol grafted nylon fiber after the reaction is completed, wherein the polyphenolic compound contains a catechol group, and the aqueous solution of the polyphenolic compound has a concentration of 1 g/L to 5 g/L; (2) immersing the polyphenol grafted nylon fiber obtained in the step (1) into a solution containing silver ions at 15 C. to 25 C. for reaction, and raising the temperature to 70 C. to 80 C. for continuous reaction to obtain a surface-activated nylon fiber, wherein in the solution containing silver ions, the concentration of silver ions is 110.sup.5 mol/L to 310.sup.5 mol/L; and (3) carrying out chemical silver plating treatment on the surface-activated nylon fiber obtained in the step (2) to obtain the silver-plated conductive nylon fiber.

2. The method according to claim 1, wherein before the step (1), the method further comprises step (1a): soaking the nylon fiber in sulfuric acid with a concentration of 20 mL/L to 100 mL/L at 40 C. to 60 C. for 20 to 120 min.

3. The method according to claim 1, wherein the chemical silver plating comprises: soaking the surface-activated nylon fiber obtained in the step (2) in a silver ammonia solution added with a reducing agent at 30 C. to 50 C. for reaction for 20 to 90 min.

4. The method according to claim 3, wherein the reducing agent is selected from the group consisting of glucose, acetaldehyde, formaldehyde or any combination thereof.

5. The method according to claim 3, wherein the silver ammonia solution is further added with a surfactant.

6. The method according to claim 5, wherein the surfactant comprises polyvinylpyrrolidone and/or sodium dodecyl benzene sulfonate.

7. The method according to claim 5, wherein the surfactant has a concentration of 5 g/L to 15 g/L.

8. The method according to claim 1, wherein in the step (1), the polyphenolic compound is selected from the group consisting of eugenol, tannic acid, ferulic acid, chlorogenic acid and any combination thereof; the water-soluble oxidant is selected from the group consisting of sodium perborate, potassium perborate, sodium persulfate and any combination thereof; and in the reaction solution, the water-soluble oxidant has a concentration of 1 g/L to 3 g/L.

9. The method according to claim 1, wherein after the step (3), the method further comprises a step (4): washing and dehydrating the silver-plated conductive nylon fiber, and drying at 90 C. to 140 C. for 2 to 10 min.

10. A silver-plated conductive nylon fiber prepared by the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 shows SEM images of the surface of the nylon fiber before treatment (a), after treatment by polymerized tannic acid in Example 1 (b), after treatment by silver nitrate activation in Example 1 (c), after treatment in Example 1 (d), and after treatment in Example 2 (e), and an SEM image of grains on the surface of the nylon fiber after treatment in Example 2 (f).

[0032] FIG. 2(a) shows a Michael addition reaction formula involved in the principle of the preparation method; FIG. 2(b) shows a Schiff reaction formula involved in the principle of the preparation method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The specific embodiments of the invention will be described in further detail with reference to tables and examples. The following examples are intended to illustrate the invention, instead of limiting the scope of the invention.

Example 1

[0034] a) Cleaning of nylon 56 fiber: The nylon 56 fiber was cleaned with a detergent to remove oil and dirt on the nylon surface for later use. [0035] b) Coarsening of nylon fiber: The nylon 56 fiber was immersed in sulfuric acid with a concentration of 20 mL/L at 40 C. for 30 min, and then washed and dehydrated. [0036] c) Polymerization of polyphenols on the fiber surface: The nylon 56 fiber coarsened in the step b) was immersed in an aqueous solution containing 1 g/L of tannic acid, and shaken at 70 C. for 30 min. Sodium perborate was added to the aqueous solution until the concentration reached 3 g/L. The resultant aqueous solution was shaken at 70 C. for 30 min to polymerize the polyphenols on the fiber surface. Then the fiber was taken out, washed and dehydrated. [0037] d) Formation of active centers: A low-concentration silver nitrate solution was prepared. The fiber obtained in the step c) was immersed in the solution for 10 min. Then the temperature was raised to 80 C., and after the reaction was carried out under shaking for 10 min, the fiber was taken out and dehydrated to obtain surface-activated nylon 56 fiber with a large number of reaction centers. [0038] e) Silver plating on fiber surface: A silver nitrate aqueous solution of 10 g/L concentration was prepared. Aqueous ammonia was added dropwise to the silver nitrate aqueous solution, and the solution was precipitated subsequently. Aqueous ammonia was continuously added dropwise until the precipitation completely disappears to obtain a silver ammonia solution. Polyvinylpyrrolidone with a molecular weight of 1,300,000 and a concentration of 0.05 g/L was added to the silver ammonia solution, followed by the addition of glucose with a concentration of 40 g/L. The nylon 56 fiber treated in the step d) was immersed in the solution, and reacted under stirring at 30 C. for 20 min, so that the fiber surface fully underwent a redox reaction. [0039] f) Cleaning and solidifying: The nylon fiber was taken out, washed thoroughly with water, and quickly dried at 100 C. for 7 min to obtain a silver-plated conductive nylon 56 fiber modified by the polyphenolic compound.

[0040] FIG. 1(a) shows an SEM image of the surface of the nylon 56 fiber before treatment in the step a). FIG. 1(b) shows an SEM image of the surface of the nylon 56 fiber after treatment by polymerized tannic acid in the step c). FIG. 1(c) shows an SEM image of the surface of the nylon 56 fiber after activation treatment by low-concentration silver nitrate in the step d). FIG. 1(d) shows a low-magnification SEM image of the surface of the nylon 56 fiber after treatment. It can be seen that before treatment, the surface of the nylon 56 fiber was smooth; after the polymerization of tannic acid, the surface of the fiber was covered with a layer of dense polymerized polyphenol; after activation treatment by low-concentration silver nitrate, many nano-silver reaction centers for subsequent reactions were adhered to the fiber surface; and after silver plating, the surface of the fiber was covered with a layer of dense silver elemental grains, and the surface was coarse. As can be seen from Table 1, the treated nylon 56 fiber had good electrical conductivity.

Example 2

[0041] a) Cleaning of nylon 56 fiber: The nylon 56 fiber was cleaned with a detergent to remove oil and dirt on the nylon surface for later use. [0042] b) Coarsening of nylon 56 fiber: The nylon 56 fiber was immersed in sulfuric acid with a concentration of 20 mL/L at 40 C. for 30 min, and then washed and dehydrated. [0043] c) Polymerization of polyphenols on the fiber surface: The nylon fiber coarsened in the step b) was immersed in an aqueous solution containing 2 g/L of ferulic acid, and shaken at 75 C. for 25 min. Sodium perborate was added to the aqueous solution until the concentration reached 2 g/L. The resultant aqueous solution was shaken at 75 C. for 25 min to polymerize the polyphenols on the fiber surface. Then the fiber was taken out, washed and dehydrated. [0044] d) Formation of active centers: A low-concentration silver nitrate solution was prepared. The fiber obtained in the step c) was immersed in the solution for 20 min. Then the temperature was raised to 80 C., and after the reaction was shaken carried out under shaking for 20 min, the fiber was taken out and dehydrated to obtain surface-activated nylon 56 fiber with a large number of reaction centers. [0045] e) Silver plating on fiber surface: A silver nitrate aqueous solution of 10 g/L concentration was prepared. Aqueous ammonia was added dropwise to the silver nitrate aqueous solution, and the solution was precipitated subsequently. Aqueous ammonia was continuously added dropwise until the precipitation completely disappears to obtain a silver ammonia solution. Polyvinylpyrrolidone with a molecular weight of 1,000,000 and concentration of 0.1 g/L was added to the silver ammonia solution, followed by the addition of glucose with a concentration of 30 g/L. The nylon 56 fiber treated in the step d) was immersed in the solution, and reacted under stirring at 50 C. for 70 min, so that the fiber surface fully underwent a redox reaction. [0046] f) Cleaning and solidifying: The nylon fiber was taken out, washed thoroughly with water, and quickly dried at 110 C. for 5 min to obtain a silver-plated conductive nylon 56 fiber modified by the polyphenolic compound.

[0047] FIG. 1(e) shows a low-magnification SEM image of the surface of the nylon 56 fiber after treatment by the step f) in this example. FIG. 1(f) shows an SEM image of nano-scale silver on the surface of the nylon 56 fiber after treatment by the step f) in this example. It can be clearly seen that the surface of the fiber was covered with a layer of dense silver elemental grains, and the surface was rough. As can be seen from Table 1, the treated nylon 56 fiber had good electrical conductivity.

Example 3

[0048] a) Cleaning of nylon 56 fiber: The nylon fiber was cleaned with a detergent to remove oil and dirt on the nylon surface for later use. [0049] b) Coarsening of nylon 56 fiber: The nylon 56 fiber was immersed in sulfuric acid with a concentration of 20 mL/L at 40 C. for 30 min, and then washed and dehydrated. [0050] c) Polymerization of polyphenols on the fiber surface: The nylon fiber coarsened in the step b) was immersed in an aqueous solution containing 1 g/L of eugenol, and shaken at 80 C. for 20 min. Sodium persulfate was added to the aqueous solution until the concentration reached 2 g/L. The resultant aqueous solution was shaken at 80 C. for 25 min to polymerize the polyphenols on the fiber surface. Then the fiber was taken out, washed and dehydrated. [0051] d) Formation of active centers: A low-concentration silver nitrate solution was prepared. The fiber obtained in the step c) was immersed in the solution for 20 min. Then the temperature was raised to 70 C., and after the reaction was carried out under shaking for 20 min, the fiber was taken out and dehydrated to obtain surface-activated nylon 56 fiber with a large number of reaction centers. [0052] e) Silver plating on fiber surface: A silver nitrate aqueous solution of 5 g/L concentration was prepared. Aqueous ammonia was added dropwise to the silver nitrate aqueous solution, and the solution was precipitated subsequently. Aqueous ammonia was continuously added dropwise until the precipitation completely disappears to obtain a silver ammonia solution. Sodium dodecylbenzenesulfonate with a concentration of 0.08 g/L was added to the silver ammonia solution, followed by the addition of glucose with a concentration of 20 g/L. The nylon 56 fiber treated in the step d) was immersed in the solution, and reacted under stirring at 30 C. for 60 min, so that the fiber surface fully underwent a redox reaction. [0053] f) Cleaning and solidifying: The nylon fiber was taken out, washed thoroughly with water, and quickly dried at 120 C. for 3 min to obtain a silver-plated conductive nylon 56 fiber modified by the polyphenolic compound.

[0054] The surface of the nylon 56 fiber treated with eugenol was covered with dense silver elemental grains, and the fiber surface was rough, had certain fastness and strength, and had good electrical conductivity.

Example 4

[0055] a) Cleaning of nylon 56 fiber: The nylon 56 fiber was cleaned with a detergent to remove oil and dirt on the nylon surface for later use. [0056] b) Coarsening of nylon 56 fiber: The nylon 56 fiber was immersed in sulfuric acid with a concentration of 30 mL/L at 40 C. for 30 min, and then washed and dehydrated. [0057] c) Polymerization of polyphenols on the fiber surface: The nylon 56 fiber coarsened in the step b) was immersed in an aqueous solution containing 1 g/L of chlorogenic acid, and shaken at 75 C. for 20 min. Sodium perborate was added to the aqueous solution until the concentration reached 3 g/L. The resulting aqueous solution was shaken at 75 C. for 30 min to polymerize the polyphenols on the fiber surface. Then the fiber was taken out, washed and dehydrated. [0058] d) Formation of active centers: A low-concentration silver nitrate solution was prepared. The fiber obtained in the step c) was immersed in the solution for 20 min. Then the temperature was raised to 70 C., and after the reaction was carried out under shaking for 10 min, the fiber was taken out and dehydrated to obtain surface-activated nylon 56 fiber with a large number of reaction centers. [0059] e) Silver plating on fiber surface: A silver nitrate aqueous solution of 10 g/L concentration was prepared. Aqueous ammonia was added dropwise to the silver nitrate aqueous solution, and the solution was precipitated subsequently. Aqueous ammonia was continuously added dropwise until the precipitation completely disappears to obtain a silver ammonia solution. Polyvinylpyrrolidone with a molecular weight of 1,300,000 and concentration of 0.1 g/L was added to the silver ammonia solution, followed by the addition of glucose with a concentration of 30 g/L. The nylon 6 fiber treated in the step d) was immersed in the solution, and reacted under stirring at 50 C. for 30 min, so that the fiber surface fully underwent a redox reaction. [0060] f) Cleaning and solidifying: The nylon fiber was taken out, washed thoroughly with water, and quickly dried at a high temperature of 80 C. for 30 min to obtain a silver-plated conductive nylon 56 fiber modified by the polyphenolic compound.

[0061] The surface of the nylon 56 fiber treated with chlorogenic acid was covered with dense silver elemental grains, and the fiber surface was rough, had certain fastness and strength, and had good electrical conductivity.

Example 5

[0062] a) Cleaning of nylon 66 fiber: The nylon 66 fiber was cleaned with a detergent to remove oil and dirt on the nylon surface for later use. [0063] b) Coarsening of nylon 66 fiber: The nylon 66 fiber was immersed in sulfuric acid with a concentration of 20 mL/L at 40 C. for 30 min, and then washed and dehydrated. [0064] c) Polymerization of polyphenols on the fiber surface: The nylon 66 fiber coarsened in the step b) was immersed in an aqueous solution containing 1 g/L of ferulic acid, and shaken at 75 C. for 20 min. Potassium perborate was added to the aqueous solution until the concentration reached 3 g/L. The resultant aqueous solution was shaken at 75 C. for 30 min to polymerize the polyphenols on the fiber surface. Then the fiber was taken out, washed and dehydrated. [0065] d) Formation of active centers: A low-concentration silver nitrate solution was prepared. The fiber obtained in the step c) was immersed in the solution for 10 min. Then the temperature was raised to 80 C., and after the reaction was carried out under shaking for 20 min, the fiber was taken out and dehydrated to obtain surface-activated nylon 66 fiber with a large number of reaction centers. [0066] e) Silver plating on fiber surface: A silver nitrate aqueous solution of 10 g/L concentration was prepared. Aqueous ammonia was added dropwise to the silver nitrate aqueous solution, and the solution was precipitated subsequently. Aqueous ammonia was continuously added dropwise until the precipitation completely disappears to obtain a silver ammonia solution. Polyvinylpyrrolidone with a molecular weight of 500000 and concentration of 0.2 g/L was added to the silver ammonia solution, followed by the addition of glucose with a concentration of 10 g/L. The nylon 66 fiber treated in the step d) was immersed in the solution, and reacted under stirring at 30 C. for 60 min, so that the fiber surface fully underwent a redox reaction. [0067] f) Cleaning and solidifying: The nylon fiber was taken out, washed thoroughly with water, and quickly dried at 90 C. for 10 min to obtain a silver-plated conductive nylon 66 fiber modified by the polyphenolic compound.

[0068] The surface of the nylon 66 fiber treated with ferulic acid was covered with dense silver elemental grains, and the fiber surface was rough, had certain fastness and strength, and had good electrical conductivity.

Example 6

[0069] a) Cleaning of nylon 6 fiber: The nylon 6 fiber was cleaned with a detergent to remove oil and dirt on the nylon surface for later use. [0070] b) Coarsening of nylon 6 fiber: The nylon 6 fiber was immersed in sulfuric acid with a concentration of 30 mL/L at 40 C. for 30 min, and then washed and dehydrated. [0071] c) Polymerization of polyphenols on the fiber surface: The nylon 6 fiber coarsened in the step b) was immersed in an aqueous solution containing 1 g/L of eugenol, and shaken at 75 C. for 20 min. Sodium perborate was added to the aqueous solution until the concentration reached 3 g/L. The resultant aqueous solution was shaken at 75 C. for 30 min to polymerize the polyphenols on the fiber surface. Then the fiber was taken out, washed and dehydrated. [0072] d) Formation of active centers: A low-concentration silver nitrate solution was prepared. The fiber obtained in the step c) was immersed in the solution for 20 min. Then the temperature was raised to 70 C., and after the reaction was carried out under shaking for 10 min, the fiber was taken out and dehydrated to obtain surface-activated nylon 6 fiber with a large number of reaction centers. [0073] e) Silver plating on fiber surface: A silver nitrate aqueous solution of 10 g/L concentration was prepared. Aqueous ammonia was added dropwise to the silver nitrate aqueous solution, and the solution was precipitated subsequently. Aqueous ammonia was continuously added dropwise until the precipitation completely disappears to obtain a silver ammonia solution. Polyvinylpyrrolidone with a molecular weight of 1,300,000 and concentration of 0.1 g/L was added to the silver ammonia solution, followed by the addition of glucose with a concentration of 30 g/L. The nylon 6 fiber treated in the step d) was immersed in the solution, and reacted under stirring at 50 C. for 30 min, so that the fiber surface fully underwent a redox reaction. [0074] f) Cleaning and solidifying: The nylon fiber was taken out, washed thoroughly with water, and quickly dried at 110 C. for 8 min to obtain a silver-plated conductive nylon 6 fiber modified by the polyphenolic compound.

[0075] The surface of the nylon 6 fiber treated with eugenol was covered with dense silver elemental grains, and the fiber surface was rough, had certain fastness and strength, and had good electrical conductivity.

Performance Tests

[0076] A fiber mechanical test (according to GB/T 14337-2008), electrical performance test (according to FZ/T 52032-2014), and fastness to soaping test (according to GB/T 14337-2008) were carried out on the conductive fibers prepared in the above examples. The results are shown in Tables 1 to 3.

TABLE-US-00001 TABLE 1 Resistance of silver-coated conductive nylon fibers prepared in different examples Examples Example Example Example Example Example Example 1 2 3 4 5 6 Electrical 183.15 47.78 109.89 122.10 33.30 1861.05 conductivity S/m

TABLE-US-00002 TABLE 2 Changes in fiber strength at different stages in Example 1 After After coarsening polymerization After Before with of silver Stage treatment sulfuric acid tannic acid plating Strength 386 357 350 344 cN/cm

TABLE-US-00003 TABLE 3 Fastness to soaping of silver-plated conductive nylon fibers prepared in Example 1 Soaping times 1 2 3 4 5 Electrical 138.05 118.15 116.76 111.35 110.87 conductivity S/m Soaping times 6 7 8 9 10 Electrical 108.94 108.25 107.78 107.54 107.23 conductivity S/m

[0077] To sum up, it can be clearly seen that in the embodiments provided by the invention, a polymerized polyphenol layer and a conductive layer are formed on the surface of nylon fiber without using a heavy metal sensitizer, to obtain a conductive nylon fiber. The preparation process is safe and environment-friendly. The conductive nylon fiber obtained by the method has excellent electrical conductivity and the strength of the nylon fiber is basically not damaged. The conductive layer is firmly bonded and does not easily fall off.

[0078] While preferred embodiments of the invention have been described above, the invention is not limited thereto. It should be appreciated that some improvements and variations can be made by those skilled in the art without departing from the technical principles of the invention, which are also contemplated to be within the scope of the invention.