METHOD FOR PLATING NONWOVEN FABRIC BY USING CONTINUOUS ELECTROLESS AND ELECTROLYTIC PLATING PROCESSES

Abstract

The present invention relates to: a method for plating nonwoven fabric with metals (copper and nickel, or nickel and nickel) by electroless and electrolytic continuous processes; and a nonwoven fabric plated by the method. The present invention can prepare a metal-plated nonwoven fabric by electrolytic plating a space of metal ions, which are formed by performing electroless plating with copper or nickel, with nickel in a short amount of time, thereby filling up the space, and thus has excellent conductivity while being thin. A desired conductivity can be obtained by changing the composition of a plating solution or controlling the plating velocity, and a line capable of performing plating with copper and nickel, nickel and nickel, nickel alone, or copper alone, in combination, can be manufactured. In addition, a highly conductive nonwoven fabric having no difference in plating thickness of nonwoven fabric performed by only electroless plating can be produced.

Claims

1. A method for plating a non-woven fabric with metals through continuous electroless and electrolytic processes, the method comprising: (a) allowing a non-woven fabric to pass through an electroless plating liquid to plate the non-woven fabric with copper for 6-10 minutes, the electroless plating liquid containing, on the basis of the volume of pure water, 2.5-5.5 g/l Cu ions, 20-55 g/l EDTA, 2.5-4.5 g/l formalin, 2-6 g/l triethanolamine (TEA), 8-12 ml/l 25% NaOH, and 0.008-0.15 g/l 2,2-bipiridine and having a pH of 12-13 and a temperature of 36-45 C.; and (b) allowing the copper-plated non-woven fabric in step (a) to pass through an electrolytic plating liquid to plate the copper-plated non-woven fabric with nickel for 1-3 minutes, the electrolytic plating liquid containing 280-320 g/l Ni(NH.sub.2SO.sub.3).sub.2, 15-25 g/l NiCl.sub.2, and 35-45 g/l H.sub.3BO.sub.3 and having a pH of 4.0-4.2 and a temperature of 50-60 C.

2. (canceled)

3. The method of claim 1, wherein the non-woven fabric is manufactured from a carbon fiber, a polyester fiber, a glass fiber, an aramid fiber, a ceramic fiber, a metal fiber, a polyimide fiber, a polybenzoxazole fiber, a natural fiber, or a mixed fiber thereof.

4. The method of claim 3, wherein the polyester fiber is polyethylene terephthalate (PET), polyglycolide (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polyethylene adipate (PEA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), or Vectran.

5. The method of claim 1, wherein in step (a), the non-woven fabric is allowed to pass through an electroless plating liquid to plate the non-woven fabric with copper for 6-10 minutes, the electroless plating liquid containing, on the basis of the volume of pure water, 4.5-5.5 g/l Cu ions, 45-55 g/l EDTA, 3.5-4.5 g/l formalin, 4-6 g/l triethanolamine (TEA), 8-12 ml/l 25% NaOH, and 0.01-0.15 g/l 2,2-bipiridine and having a pH of 12-13 and a temperature of 40-45 C.

6. The method of claim 1, wherein step (b) is performed by applying a constant voltage (CV) of 5-15 V.

7. The method of claim 1, wherein the non-woven fabric in step (a) is pre-treated, before step (a), by a method comprising the following steps: (i) degreasing and softening the non-woven fabric by allowing the non-woven fabric to pass through an aqueous solution containing a surfactant, an organic solvent, and a non-ionic surfactant; (ii) performing an etching process for neutralizing, cleaning, and conditioning actions by allowing the non-woven fabric as the product in step (a) to pass through an aqueous solution containing sodium bisulfite (NaHSO.sub.3), sulfuric acid (H.sub.2SO.sub.4), ammonium persulfate ((NH.sub.4).sub.2S.sub.2O.sub.8), and pure water; (iii) performing a sensitizing process by allowing the non-woven fabric as the product in step (ii) to an aqueous solution of PdCl.sub.2; and (iv) performing an activating process by allowing the non-woven fabric as the product in step (iii) to pass through an aqueous solution of sulfuric acid (H.sub.2SO.sub.4).

8. The method of claim 7, wherein the aqueous solution in step (i) contains: as a surfactant, 15-35 wt % of a solution in which pure water and NaOH are mixed at a weight ratio of 40-49:1-10; as organic solvents, 50-80 wt % of diethyl propanediol and 5-15 wt % of dipropylene glycol methyl ether; and 400-600 ppm of a non-ionic surfactant.

9. The method of claim 7, wherein the aqueous solution in step (ii) contains 0.1-10 wt % of sodium bisulfite (NaHSO.sub.3), 0.1-3 wt % of sulfuric acid (H.sub.2SO.sub.4), 5-25 wt % of ammonium persulfate ((NH.sub.4).sub.2S.sub.2O.sub.8), and 62-94.8 wt % of pure water.

10. The method of claim 7, wherein step (i) is performed at a temperature of 40-60 C. for 1-5 min, step (ii) is performed at a temperature of 20-25 C. for 1-5 min, step (iii) is performed at a temperature of 20-40 C. for 1-5 min, and step (iv) is performed at a temperature of 40-60 C. for 1-5 min.

11. A method for plating a non-woven fabric with metals through continuous electroless and electrolytic processes, the method comprising: (a) allowing a non-woven fabric to pass through an electroless plating liquid to plate the non-woven fabric with nickel for 6-10 minutes, the electroless plating liquid containing, on the basis of the volume of pure water, 5-7 g/l Ni ions, 20-30 g/l NaH.sub.2PO.sub.2, 20-30 g/l Na.sub.3C.sub.6H.sub.5O.sub.7, and 0.0005-0.001 g/l potassium thiosulfate and having a pH of 8.5-9.5 and a temperature of 30-35 C.; and (b) allowing the nickel-plated non-woven fabric in step (a) to pass through an electrolytic plating liquid to plate the nickel-plated non-woven fabric with nickel for 1-3 minutes, the electrolytic plating liquid containing 280-320 g/l Ni(NH.sub.2SO.sub.3).sub.2, 15-25 g/l NiCl.sub.2, and 35-45 g/l H.sub.3BO.sub.3 and having a pH of 4.0-4.2 and a temperature of 50-55 C.

12. The method of claim 11, wherein the non-woven fabric is manufactured from a carbon fiber, a polyester fiber, a glass fiber, an aramid fiber, a ceramic fiber, a metal fiber, a polyimide fiber, a polybenzoxazole fiber, a natural fiber, or a mixed fiber thereof.

13. The method of claim 12, wherein the polyester fiber is polyethylene terephthalate (PET), polyglycolide (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polyethylene adipate (PEA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), or Vectran.

14. The method of claim 11, wherein step (b) is performed by applying a constant voltage (CV) of 5-15 V.

15. The method of claim 11, wherein the non-woven fabric in step (a) is pre-treated, before step (a), by a method comprising the following steps: (i) degreasing and softening the non-woven fabric by allowing the non-woven fabric to pass through an aqueous solution containing a surfactant, an organic solvent, and a non-ionic surfactant; (ii) performing an etching process for neutralizing, cleaning, and conditioning actions by allowing the non-woven fabric as the product in step (a) to pass through an aqueous solution containing sodium bisulfite (NaHSO.sub.3), sulfuric acid (H.sub.2SO.sub.4), ammonium persulfate ((NH.sub.4).sub.2S.sub.2O.sub.8), and pure water; (iii) performing a sensitizing process by allowing the non-woven fabric as the product in step (ii) to an aqueous solution of PdCl.sub.2; and (iv) performing an activating process by allowing the non-woven fabric as the product in step (iii) to pass through an aqueous solution of sulfuric acid (H.sub.2SO.sub.4).

16. The method of claim 15, wherein the aqueous solution in step (i) contains: as a surfactant, 15-35 wt % of a solution in which pure water and NaOH are mixed at a weight ratio of 40-49:1-10; as organic solvents, 50-80 wt % of diethyl propanediol and 5-15 wt % of dipropylene glycol methyl ether; and 400-600 ppm of a non-ionic surfactant.

17. The method of claim 15, wherein the aqueous solution in step (ii) contains 0.1-10 wt % of sodium bisulfite (NaHSO.sub.3), 0.1-3 wt % of sulfuric acid (H.sub.2SO.sub.4), 5-25 wt % of ammonium persulfate ((NH.sub.4).sub.2S.sub.2O.sub.8), and 62-94.8 wt % of pure water.

18. The method of claim 15, wherein step (i) is performed at a temperature of 40-60 C. for 1-5 min, step (ii) is performed at a temperature of 20-25 C. for 1-5 min, step (iii) is performed at a temperature of 20-40 C. for 1-5 min, and step (iv) is performed ata temperature of 40-60 C. for 1-5 min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0089] FIG. 1 illustrates an apparatus for surface treatment of a nonwoven fabric according to the present invention (side view). FIG. 1 is a schematic view illustrating that the apparatus works through installed rollers in an arrow direction. A carbon fiber nonwoven fabric or a PET nonwoven fabric is allowed to pass through a pre-treatment bath for determining the adhesive strength of the plating and the pre-treatment for the plating, followed by primary plating in an electroless plating bath. Here, copper or nickel may be selected for electroless plating. After the primary electroless plating, the nonwoven fabric, which has been subjected to electroless plating, is finally subjected to nickel plating. The electrolytic plating is carried out by connecting an electroless plate to a positive (+) electrode and connecting a roller to a negative () electrode, and finally, a conductive nonwoven fabric having a double structure of copper-nickel or nickel-nickel is manufactured as a product.

MODE FOR CARRYING OUT THE INVENTION

[0090] Hereinafter, the present invention will be described in detail with reference to examples. These examples are only for illustrating the present invention more specifically, and it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples.

EXAMPLES

[0091] Throughout the present specification, the term % used to express the concentration of a specific material, unless otherwise particularly stated, refers to (wt/wt)% for solid/solid, (wt/vol)% for solid/liquid, and (vol/vol)% for liquid/liquid.

Example 1

Manufacturing of Carbon Fiber Nonwoven Fabric and PET Nonwoven Fabric

[0092] Carbon Fiber Nonwoven Fabric

[0093] A carbon fiber nonwoven fabric was prepared in a form of a wet-laid nonwoven fabric.

[0094] First, carbon fibers (12K, purchased from Toray, Hyosung, or Taekwang (TK)) were cut into about 6 mm in length, and the cut carbon fiber chops were dispersed in water. The dispersed carbon fiber chops are allowed to float on the water, and were allowed to form a layer with a predetermined thickness in the water through left and right vibration. Then, the carbon fiber layer was taken up, dried, and then compressed using a roller, thereby manufacturing a nonwoven fabric.

[0095] Meanwhile, in order to increase the strength of the nonwoven fabric, L/M PET (low-melting PET chop 6 mm) was dispersed together with 6 mm-length carbon fiber chops in water, followed by compressing using a heating roller at 100 C., thereby manufacturing a nonwoven fabric. L/M PET can be melted at about 100 C., and thus, a nonwoven fabric manufactured by mixing a small amount of L/M PET with carbon fibers and heating and compressing the mixture has a stronger intensity compared with a nonwoven fabric manufactured of 100% carbon fibers.

[0096] PET Nonwoven Fabric

[0097] The PET nonwoven fabric was manufactured in a wet-laid form. The

[0098] PET nonwoven fabric was manufactured by the method same as the foregoing method for manufacturing a carbon fiber nonwoven fabric except that 6 mm-length chops of PET (purchased from TEIJIN, Japan) instead of a carbon fiber were used. As described above, in order to increase the intensity of the PET nonwoven fabric, a predetermined amount of L/M PET may be added to manufacture a nonwoven fabric.

[0099] Pre-Treatment of Carbon Fiber Nonwoven Fabric and PET Nonwoven Fabric

[0100] 1) Degreasing and Softening Processes

[0101] First, a process was performed that removes epoxy or urethane sized on the carbon fibers and softens surfaces of the fibers through swelling at the same time by using an organic solvent.

[0102] The degreasing and softening process was performed by allowing the carbon fiber nonwoven fabric or the PET nonwoven fabric in example 1 to pass through a pretreatment bath containing: as a surfactant, 25 wt % of a solution in which pure water and NaOH were mixed at a weight ratio of 47:3; as organic solvents, 65 wt % of diethyl propanediol and 10 wt % of dipropylene glycol methyl ether; and, as a non-ionic surfactant (low foam), 500 ppm ethoxylated linear alcohol. The degreasing and softening process was performed at a temperature of 50 C. for 2 minutes.

[0103] 2) Etching Process

[0104] An etching process was performed to neutralize a strong alkali component of NaOH using sulfuric acid (H.sub.2SO.sub.4), reduce the load of a sensitizing process as a next process, and perform a washing action and a conditioning action using ammonium peroxysulfate ((NH.sub.4).sub.2S.sub.2O.sub.8), thereby enhancing the adsorption of palladium.

[0105] Specifically, an etching process was performed by allowing the nonwoven fabric, which had gone through the degreasing and softening process, to pass through a pretreatment bath containing 1 wt % of sodium bisulfate (NaHSO.sub.3), 0.5 wt % of sulfuric acid (H.sub.2SO.sub.4), 5 wt % of ammonium persulfate ((NH.sub.4).sub.2S.sub.2O.sub.8), and 83.5 wt % of pure water, to perform neutralizing, washing, and conditioning actions. The etching process was performed at a temperature of 20-25 C. for 2 minutes.

[0106] 3) Sensitizing Process (Catalyst Imparting Process)

[0107] A sensitizing process was performed by treating the nonwoven fabric, which had gone through the etching process, with 20% PdCl.sub.2 at a temperature of 30 C. for 2 minutes. The sensitizing process is performed in order to allow metal ions to be adsorbed on surfaces of the surface-modified carbon fibers or PET.

[0108] 4) Activating Process

[0109] For an activating process, which is performed together with the sensitizing process, the nonwoven fabric was treated with 10% sulfuric acid (H.sub.2SO.sub.4) at a temperature of 50 C. for 2 minutes in order to remove colloidized Sn for the prevention of Pd oxidation.

[0110] The nonwoven fabric was pre-treated by the above processes. The carbon fiber nonwoven fabric and the PET nonwoven fabric were pretreated by the same processes.

Examples 2 and 3

Copper and Nickel-Plated Carbon Fibers Obtained by Continuous Electroless and Electrolytic Plating Processes

[0111] The carbon fibers (12K, purchased from Toray) pretreated in example 1 and the carbon fibers (12K, purchased from Taekwang (TK)) pretreated in example 1 were subjected to an electroless copper plating process under the composition and conditions shown in table 1 below and then continuously subjected to an electrolytic nickel plating process under the composition and conditions shown in table 2 below, using a plating apparatus shown in the accompanying FIG. 1, thereby preparing copper and nickel-plated carbon fibers, which were then used for examples 2 and 3, respectively. Hereinafter, the contents of ingredients of the plating liquids are on the basis of 1 L of pure water.

TABLE-US-00001 TABLE 1 Electroless Cu plating liquid Ingredient Content (conditions) Metal salt Cu ion 3 g/l Complexing agent EDTA 30 g/l Reducing agent Formalin 3.0 g/l Stabilizer TEA (Triethnaol amine) 3 g/l 2,2-bipiridine 0.01 g/l pH Adjusting agent NaOH (25%) 12 ml/l Temperature 38 C. pH 12.5 Treatment time 6 min

TABLE-US-00002 TABLE 2 Electrolytic Ni plating liquid Ingredient Content (conditions) Electrolytic Nickel metal salt Ni(NH.sub.2SO.sub.3).sub.2 300 g/l plating solution NiCl.sub.2 20 g/l pH Buffer H.sub.3BO.sub.3 40 g/l Temperature 55 C. pH 4.2 Treatment time 1 min

Example 4

Copper and Nickel-Plated Carbon Fibers Obtained by Continuous Electroless and Electrolytic Plating Processes

[0112] The carbon fibers pretreated in example 1 were subjected to an electroless copper plating process under the composition and conditions shown in table 3 below and then continuously subjected to an electrolytic nickel plating process under the composition and conditions shown in table 4 below, using the plating apparatus in the accompanying FIG. 1, thereby preparing copper and nickel-plated carbon fibers.

TABLE-US-00003 TABLE 3 Electroless Cu plating liquid Ingredient Content (conditions) Metal salt Cu ion 2.5-3.5 g/l Complexing agent EDTA 25-35 g/l Reducing agent Formalin 2.5-3.5 g/l Stabilizer TEA (Triethnaol amine) 2-3 g/l 2,2-bipiridine 0.008-0.01 g/l pH Adjusting agent NaOH (25%) 8-12 ml/l Temperature 36-40 C. pH 12-13 Treatment time 6-10 min

TABLE-US-00004 TABLE 4 Electrolytic Ni plating liquid Ingredient Content (conditions) Electrolytic Nickel metal salt Ni(NH.sub.2SO.sub.3).sub.2 280-320 g/l plating solution NiCl.sub.2 15-25 g/l pH Buffer H.sub.3BO.sub.3 35-45 g/l Temperature 50-55 C. pH 4.0-4.2 Treatment time 1-3 min

[0113] For the electrolytic plating, a constant voltage (CV) of 5-10 V was applied to an electrolytic nickel bath. A Ni metal plate or Ni balls were used for a metal plate used as a positive electrode.

Example 5

Copper and Nickel-Plated Carbon Fibers Obtained by Continuous Electroless and Electrolytic Plating Processes

[0114] The carbon fibers pretreated in example 1 were subjected to an electroless copper plating process under the composition and conditions shown in table 5 below and then continuously subjected to an electrolytic nickel plating process under the composition and conditions shown in table 6 below, using the plating apparatus in the accompanying FIG. 1, thereby preparing copper and nickel-plated carbon fibers.

TABLE-US-00005 TABLE 5 Electroless Cu plating liquid Ingredient Content (conditions) Metal salt Cu ion 4.5-5.5 g/l Complexing agent EDTA 45-55 g/l Reducing agent Formalin 3.5-4.5 g/l Stabilizer TEA(Triethnaol amine) 4-6 g/l 2,2-bipiridine 0.01-0.15 g/l pH Adjusting agent NaOH(25%) 8-12 ml/l Temperature 40-45 C. pH 12-13 Treatment time 6-10 min

TABLE-US-00006 TABLE 6 Electrolytic Ni plating liquid Ingredient Content (conditions) Electrolytic Nickel metal salt Ni(NH.sub.2SO.sub.3).sub.2 280-320 g/l plating solution NiCl.sub.2 15-25 g/l pH Buffer H.sub.3BO.sub.3 35-45 g/l Temperature 50-55 C. pH 4.0-4.2 Treatment time 1-3 min

[0115] For the electrolytic plating, a constant voltage (CV) of 5-10 V was applied to an electrolytic nickel bath. A Ni metal plate or Ni balls were used for a metal plate used as a positive electrode.

Example 6

Nickel and Nickel-Plated Carbon Fibers Obtained by Continuous Electroless and Electrolytic Plating Processes

[0116] The carbon fibers pretreated in example 1 were subjected to an electroless nickel plating process under the composition and conditions shown in table 7 below and then continuously subjected to an electrolytic nickel plating process under the composition and conditions shown in table 8 below, using the plating apparatus in the accompanying FIG. 1, thereby preparing nickel and nickel-plated carbon fibers.

TABLE-US-00007 TABLE 7 Electroless Ni plating liquid Ingredient Content (conditions) Metal salt Niion 5-7 g/l Reducing agent NaH.sub.2PO.sub.2 20-30 g/l pH Buffer Na.sub.3C.sub.6H.sub.5O.sub.7 20-30 g/l Stabilizer potassium thiosulfate 0.0005 g-0.001 g/l Temperature 30-35 C. pH 8.5-9.5 Treatment time 6-10 min

TABLE-US-00008 TABLE 8 Electrolytic Ni plating liquid Ingredient Content (conditions) Electrolytic Nickel metal salt Ni(NH.sub.2SO.sub.3).sub.2 280-320 g/l plating solution NiCl.sub.2 15-25 g/l pH Buffer H.sub.3BO.sub.3 35-45 g/l Temperature 50-55 C. pH 4.0-4.2 Treatment time 1-3 min

[0117] For the electrolytic plating, a constant voltage (CV) of 10-15 V was applied to an electrolytic nickel bath. A Ni metal plate or Ni balls were used for a metal plate used as a positive electrode.

Test Example 1

Measurement on Change in Current Density and Linear Resistance Value of Plated Carbon Fiber

[0118] The optimization conditions for electroless and electrolytic plating were set by adjusting the concentration of NaOH, which adjusts pH, and the concentration of HCHO, which helps the reduction reaction of Cu, in the composition and conditions for preparing copper and nickel-plated carbon fibers in example 4.

[0119] While the amount of 25% NaOH was changed to 8, 9, 10, 11, and 12 ml/l and the amount of HCHO was changed to 2.5, 2.7, 2.9, 3.1, and 3.3 g/l, respectively, the change in the current density (A) flowing through the carbon fibers was measured, and the linear resistance (/30 cm) of the finally obtained products (copper and nickel-plated carbon fibers) was evaluated, and the results were summarized in table 9 below. A constant voltage (CV) of 7 V was applied to an electrolytic nickel bath, and the other conditions that were uniformly maintained were summarized in tables 10 and 11 below.

TABLE-US-00009 TABLE 9 Current Plating density Resistance liquid HCHO NaOH (A) (/30 cm) run time 2.5 8 100 0.8 10 turns 9 110 0.6 10 120 0.4 11 130 0.3 12 140 0.2 2.7 8 110 0.7 8 turns 9 120 0.6 10 130 0.5 11 140 0.3 12 150 0.2 2.9 8 120 0.6 6 turns 9 130 0.5 10 140 0.4 11 150 0.3 12 160 0.2 3.1 8 130 0.6 4 turns 9 140 0.5 10 150 0.4 11 160 0.3 12 170 0.2 3.3 8 140 0.5 2 turns 9 150 0.4 10 160 0.3 11 170 0.2 12 180 0.1

[0120] In table 9 above, 1 turn represents 1 make-up amount of electroless copper plating.

TABLE-US-00010 TABLE 10 Electroless Cu plating liquid Ingredient Content (conditions) Metal salt Cu ion 3 g/l Complexing agent EDTA 30 g/l Reducing agent Formalin(HCHO) 2.5-3.3 g/l Stabilizer TEA (Triethnaol amine) 3 g/l 2,2-bipiridine 0.10 g/l pH Adjusting agent NaOH (25%) 8-12 ml/l Temperature 37 C. pH 12.5 Treatment time 6 min

TABLE-US-00011 TABLE 11 Electrolytic plating liquid Ingredient Content (conditions) Electrolytic Nickel Metal salt Ni(NH.sub.2SO.sub.3).sub.2 300 g/l plating solution NiCl.sub.2 20 g/l pH Buffer H.sub.3BO.sub.3 40 g/l Temperature 55 C. pH 4.2 Treatment time 1 min Constant voltage (Cv) 7 V

[0121] As can be confirmed from table 9 above, as the amounts of the reducing agent and NaOH were increased, the plating rate was increased, but the lifetime of the plating liquid was shortened. Therefore, it may be preferable to maintain the amount of the reducing agent at the minimum (2.5-3.0 g/l) and increase the amount of NaOH to the maximum.

Test Example 2

Tests on Plating Rate and Liquid Stability

[0122] As for tests on the plating rate and the liquid stability through the adjustment of the concentrations of copper ions and a complexing agent (EDTA), the optimization conditions for copper plating were tested by adjusting the amount of the reducing agent (table 12) when the copper ions and the complexing agent were increased at the same ratio, and the other components and conditions that were uniformly maintained were summarized in tables 13 and 14 below.

TABLE-US-00012 TABLE 12 Metal Reducing Complexing Plating salt agent agent thickness (Cu) (HCHO) (EDTA) NaOH (m) 2.5 2.5 25 12 0.2-0.3 3.5 3.0 35 12 0.3-0.5 4.5 3.5 45 12 0.4-0.6 5.5 4 55 12 0.5-0.8

TABLE-US-00013 TABLE 13 Electroless Cu plating liquid Ingredient Content (conditions) Metal salt Cu ion 2.5-5.5 g/l Complexing agent EDTA 25-55 g/l Reducing agent Formalin 2.5-4 g/l Stabilizer TEA (Triethnaol amine) 3 g/l 2,2-bipiridine 0.01 g/l pH Adjusting agent NaOH (25%) 12 ml/l Temperature 37 C. pH 12.5 Treatment time 6 min

TABLE-US-00014 TABLE 14 Electrolytic plating liquid Ingredient Content (conditions) Electrolytic Nickel Metal salt Ni(NH.sub.2SO.sub.3).sub.2 300 g/l plating solution NiCl.sub.2 20 g/l pH Buffer H.sub.3BO.sub.3 40 g/l Temperature 55 C. pH 4.2 Treatment time 1 min C.V 7 V

[0123] As can be seen from table 12 above, it was verified that, as the concentrations of copper and HCHO were higher, high-rate plating was allowable, and the thickness of the plating layer was increased (plating thickness: 0.7 m or more). For a plating thickness of 0.3 m preferable for the carbon fibers, the best products were obtained when the concentration of copper ions was 2.5-3.0 g/l and the concentration of HCHO was 2.5-3.0 g/l.

[0124] As the plating thickness of the carbon fiber increases, the specific gravity increases and the strength, elastic modulus, and strain deteriorate, and thus preferably, carbon fibers with excellent electrical conductivity are prepared by conducting Ni electrolytic plating on Cu pores in a shorter time after the electroless plating, rather than compulsorily increasing the plating thickness in the electroless plating.

Test Example 3

Comparison of Physical Properties and Electrical Conductivity

[0125] Table 15 shows the comparison of physical properties, electrical conductivity, and the like between the copper and nickel-plated carbon fibers in examples 2 and 3 and nickel-plated carbon fibers on the market prepared by an electroless plating process, as comparative example 1.

TABLE-US-00015 TABLE 15 Comparative example 1 Example 2 Example 3 Note Strand strenth 280 380 338 (kgf/mm.sup.2)(Range) (367~405) (325~353) Elastic modulus (tons/mm.sup.2) 22.0 20.0 22.5 Strain (%) 1.2 1.9 1.5 Specific gravity (g/cm.sup.3) 2.70 2.7277 2.7894 Diameter (m) 7.5 7.828 7.705 Tex (Fiber thickness) 1420 1575 1561 Electrical resistance (/m) 0.8 0.7 Electrical resistance (cm) 7.5 10.sup.5 4.62 10.sup.5 4.05 10.sup.5 Electrical resistance 32-Fold 37-Fold General CF: compared with general CF reduction redution 1.50 100.sup.3 cm base Coating thickness (nm) 250 240 350 (210~271) (305~392)

[0126] As can be seen from table 15 above, the copper and nickel-plated carbon fibers in examples 2 and 3 had excellent physical properties and exhibited excellent electrical conductivity values due to the low electrical conductivity values, compared with comparative example 1 prepared by the electroless plating process.

Example 7

Copper and Nickel-Plated Carbon Fiber Nonwoven Fabric and PET Nonwoven Fabric Obtained by Continuous Electroless and Electrolytic Plating Processes

[0127] The carbon fiber nonwoven fabric and the PET nonwoven fabric in example 1 were subjected to an electroless copper plating process in the compositions and conditions shown in table 16 below and then continuously subjected to an electrolytic nickel plating process in the compositions and conditions shown in table 17 below, using the plating apparatus in the accompanying FIG. 1, thereby manufacturing copper and nickel-plated carbon fiber nonwoven fabric and PET nonwoven fabric.

TABLE-US-00016 TABLE 16 Electroless Cu plating liquid Ingredient Content (conditions) Metal salt Cu ion 4.5-5.5 g/l Complexing agent EDTA 45-55 g/l Reducing agent Formalin 3.5-4.5 g/l Stabilizer TEA (Triethnaol amine) 4-6 g/l 2,2-bipiridine 0.01-0.15 g/l pH Adjusting agent NaOH (25%) 8-12 ml/l Temperature 40-45 C. pH 12-13 Treatment time 6-10 min

TABLE-US-00017 TABLE 17 Electrolytic Ni plating liquid Ingredient Content (conditions) Electrolytic Nickel Metal salt Ni(NH.sub.2SO.sub.3).sub.2 280-320 g/l plating solution NiCl.sub.2 15-25 g/l pH Buffer H.sub.3BO.sub.3 35-45 g/l Temperature 50-55 C. pH 4.0-4.2 Treatment time 1-3 min

[0128] For the electrolytic plating, a constant voltage (CV) of 5-10 V was applied to an electrolytic nickel bath. A Ni metal plate or Ni balls were used for a metal plate used as a positive electrode.

Example 8

Nickel-Plated Carbon Fiber Nonwoven Fabric and PET Nonwoven Fabric Obtained by Continuous Electroless and Electrolytic Plating Processes

[0129] The nonwoven fabric pretreated in example 1 was subjected to an electroless copper plating process in the compositions and conditions shown in table 18 below and then continuously subjected to an electrolytic nickel plating process in the compositions and conditions shown in table 19 below, using the plating apparatus in the accompanying FIG. 1, thereby manufacturing a nickel-plated nonwoven fabric.

TABLE-US-00018 TABLE 18 Electroless Ni plating liquid Ingredient Content (conditions) Metal salt Niion 5-7 g/l Reducing agent NaH.sub.2PO.sub.2 20-30 g/l pH Buffer Na.sub.3C.sub.6H.sub.5O.sub.7 20-30 g/l Stabilizer potassium thiosulfate 0.0005 g-0.001 g/l Temperature 30-35 C. pH 8.5-9.5 Treatment time 6-10 min

TABLE-US-00019 TABLE 19 Electrolytic Ni plating liquid Ingredient Content (conditions) Electrolytic Nickel Metal salt Ni(NH.sub.2SO.sub.3).sub.2 280-320 g/l plating solution NiCl.sub.2 15-25 g/l pH Buffer H.sub.3BO.sub.3 35-45 g/l Temperature 50-55 C. pH 4.0-4.2 Treatment time 1-3 min

[0130] For the electrolytic plating, a constant voltage (CV) of 10-15 V was applied to an electrolytic nickel bath. A Ni metal plate or Ni balls were used for a metal plate used as a positive electrode.

Test Example 4

Electrical Characteristics of Nonwoven Fabric

[0131] The plated nonwoven fabrics in examples 7 and 8 above were analyzed for electrical characteristics as shown in Table 20 and 21 below, respectively.

TABLE-US-00020 TABLE 20 Basis Electrical characteristics after Copper/ weight Nickel double plating before Surface Volume Electrical plating Resistance resisance resistance conductivity Item Composition (g/m.sup.2) () (/square) (*cm) (S/cm) 1 C/F 100% 15 2*10.sup.1 .sup.9.97*10.sup.2 3.69*10.sup.2 2.7*10.sup.1 2 C/F 80% + 20 3.88*10.sup.1 1.76*10.sup.0 3.69*10.sup.2 2.7*10.sup.1 L/M PET 20% 3 PET 80% + 5 1.79*10.sup.2 8.12*10.sup.2 1.62*10.sup.0 6.15*10.sup.1 L/M PET 20% 4 PET 60% + 10 6.91*10.sup.1 3.13*10.sup.0 1.25*10.sup.2 7.97*10.sup.1 L/M PET 40%

TABLE-US-00021 TABLE 21 Basis Electrical characteristics after Nickel/ weight Nickel double plating before Surface Volume Electrical plating Resistance resistance resistance conductivity Item Composition (g/m.sup.2) () (/square) (*cm) (S/cm) 1 C/F: 70% 15 6.62*10.sup.1 3.00*10.sup.0 5.70*10.sup.2 1.75*10.sup.1 1.1 d L/M PET: 30% C/F: Carbon fiber L/M PET: Low-melting PET PET: Polyethylene terephthalate

[0132] Although the present invention has been described in detail with reference to the specific features, it will be apparent to those skilled in the art that this description is only for a preferred embodiment and does not limit the scope of the present invention. Thus, the substantial scope of the present invention will be defined by the appended claims and equivalents thereof.