U.S. patent application number 15/326583 was filed with the patent office on 2017-07-20 for method for plating nonwoven fabric by using continuous electroless and electrolytic plating processes.
The applicant listed for this patent is BULLSONE MATERIAL CO., LTD., CLEAN & SCIENCE CO., LTD.. Invention is credited to Min Hwan CHANG, Soo Hyung HUR, Byung Rok KANG, Ji Hun KANG, Seung Won KANG, Gyu Beom KWAG, Jong Gil LEE, Nam Kwi LEE, Min Young PARK.
Application Number | 20170204519 15/326583 |
Document ID | / |
Family ID | 55078728 |
Filed Date | 2017-07-20 |
United States Patent
Application |
20170204519 |
Kind Code |
A1 |
KWAG; Gyu Beom ; et
al. |
July 20, 2017 |
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.
Inventors: |
KWAG; Gyu Beom; (Seoul,
KR) ; KANG; Seung Won; (Gyeongsangbuk-do, KR)
; LEE; Nam Kwi; (Jeollabuk-do, KR) ; CHANG; Min
Hwan; (Jeonju-si, KR) ; LEE; Jong Gil;
(Incheon, KR) ; HUR; Soo Hyung; (Seoul, KR)
; PARK; Min Young; (Incheon, KR) ; KANG; Byung
Rok; (Incheon, KR) ; KANG; Ji Hun;
(Chungcheongnam-do, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CLEAN & SCIENCE CO., LTD.
BULLSONE MATERIAL CO., LTD. |
Seoul
Incheon |
|
KR
KR |
|
|
Family ID: |
55078728 |
Appl. No.: |
15/326583 |
Filed: |
June 30, 2015 |
PCT Filed: |
June 30, 2015 |
PCT NO: |
PCT/KR2015/006719 |
371 Date: |
January 16, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 18/405 20130101;
C23C 18/24 20130101; C23C 18/2086 20130101; C23C 28/023 20130101;
C23C 18/40 20130101; C25D 5/54 20130101; C25D 3/12 20130101; C23C
18/1641 20130101; C25D 7/00 20130101; C23C 18/1653 20130101; C23C
18/30 20130101; C23C 18/1886 20130101 |
International
Class: |
C23C 18/16 20060101
C23C018/16; C23C 18/18 20060101 C23C018/18; C23C 28/02 20060101
C23C028/02; C25D 5/54 20060101 C25D005/54; C25D 7/00 20060101
C25D007/00; C23C 18/40 20060101 C23C018/40; C25D 3/12 20060101
C25D003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 17, 2014 |
KR |
10-2014-0090300 |
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.degree. 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.degree. 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 .degree. 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.degree. C. for 1-5 min, step (ii) is performed
at a temperature of 20-25.degree. C. for 1-5 min, step (iii) is
performed at a temperature of 20-40.degree. C. for 1-5 min, and
step (iv) is performed at a temperature of 40-60.degree. 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.degree. 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.degree. 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.degree. C. for 1-5 min, step (ii) is performed
at a temperature of 20-25.degree. C. for 1-5 min, step (iii) is
performed at a temperature of 20-40.degree. C. for 1-5 min, and
step (iv) is performed ata temperature of 40-60.degree. C. for 1-5
min.
Description
FIELD
[0001] This application claims priority to and the benefit of
Korean Patent
[0002] Application No. 10-2014-0090300 filed in the Korean
Intellectual Property Office on 17 Jul. 2014, the entire contents
of which are incorporated herein by reference.
[0003] The present invention relates to a method for plating a
nonwoven fabric using continuous electroless and electrolytic
plating processes and a nonwoven fabric plated by the method and,
more specifically, to a preparation of a metal-plated nonwoven
fabric to improve conductivity by enhancing the binding strength
between metals, with which a nonwoven fabric is surface-treated,
and fibers which constitute the nonwoven fabric.
BACKGROUND
[0004] Today, a carbon fiber-reinforced composite material that
starts to develop rapidly together with the development of
aerospace industries is one of the advanced materials that are used
in various fields, such as electrical and electronic materials,
civil engineering and building materials, automobiles, ships,
military equipment, and sporting goods as well as aerospace
industries.
[0005] However, the carbon fiber-reinforced composite material is
recently used in a very limited role, due to its low conductivity,
for automotive electronics and communication device housing that
need to implement mechanical properties and electromagnetic wave
shielding performance at the same time.
[0006] Therefore, in order to overcome the disadvantage, a polymer
composite material having electromagnetic shielding efficiency has
been developed by adding carbon fiber, carbon black, CNT,
TiO.sub.2, nickel-coated graphite, and the latest announced
graphene, as a filler for implementing an electromagnetic wave
shielding function, to the polymer composite material. However,
such a developed polymer composite material has many problems in
the commercialization thereof due to the problems in dispersion and
deteriorations in mechanical properties. Moreover, there are many
trials and errors due to price disadvantages and mechanical
properties.
[0007] Meanwhile, an electroless or electrolytic surface treatment
process of the conventional art, of which respective steps are
separated for conducting treatment and then re-treatment, has
problems in that the processing time is not shortened, the price
competitiveness is decreased, and the production facilities are
also not simplified.
[0008] A CVD process or a sputtering manner has been used before in
order to increase the binding strength between carbon fibers and a
metal, but does not have price competitiveness due to high
production costs, causing many problems.
[0009] Moreover, an electroless carbon fiber plating method is
somewhat limited in increasing conductivity in carbon fibers by
containing a phosphor component due to chemical ionic binding, and
an electrolytic plating method may increase conductivity, but does
not achieve uniform plating on each filament of the carbon fiber,
and thus each filament is not suitable as an important composite
material. A plated carbon fiber produced by electrolytic plating
has a lot of lint and causes a lot of filament disconnection, and
thus is limited in the use thereof as a composite material that
needs to maintain the plating states of products.
[0010] With respect to the hybrid type of the continuous process
developed in the present invention, when all filaments of carbon
fibers are first plated through electroless plating, followed by
complete removal of a chemical reagent and then electrolytic
plating, all carbon fibers are uniformly plated, and a plating
layer, which is dense between metals, is formed in spite of a short
electroplating time such that the plating layer has a small
thickness and rapidly improved conductivity, and thus is very
suitable for the use of a composite material.
[0011] In cases of the conventional production, respectively
different production processes are conducted, and thus, the
production processes had a high cost, production facilities were
very expensive, and the control of conductivity through the
adjustment of the plating thickness of a product was very
difficult.
[0012] However, the hybrid type of the continuous process developed
in the present invention has a low cost and allows easy control by
continuously performing electroless and electrolytic plating using
a single production facility, so that competitive products can be
produced and quality inspection is easy.
[0013] Throughout the entire specification, many papers and patent
documents are referenced and their citations are represented. The
disclosure of the cited papers and patent documents are entirely
incorporated by reference into the present specification, and the
level of the technical field within which the present invention
falls and the details of the present invention are explained more
clearly.
DETAILED DESCRIPTION
Technical Problem
[0014] The present inventors searched and endeavored to develop a
method for preparing a metal-plated fiber nonwoven fabric with
excellent economical feasibility and conductivity, and as a result,
the present inventors verified that the adoption of the continuous
electroless and electrolytic surface treatment processes has
advantages in shortening of the process time, having price
competitiveness, and simplifying production facilities when
compared with only an electroless or electrolytic surface treatment
process of the conventional art, and induces not only dense plating
between metal structures, leading excellent conductivity, but also
low production costs, when compared with products of the
conventional art.
[0015] Accordingly, an aspect of the present invention is to
provide a method for plating a non-woven fabric with metals (cooper
and nickel) through continuous electroless and electrolytic
processes.
[0016] Another aspect of the present invention is to provide a
non-woven fabric plated with metals (cooper and nickel).
[0017] Other purposes and advantages of the present invention will
become more obvious with the following detailed description of the
invention, claims, and drawings.
Technical Solution
[0018] In accordance with an aspect of the present invention, there
is provided a method for plating a non-woven fabric with metals
through continuous electroless and electrolytic processes, the
method comprising:
[0019] (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.degree. C.; and
[0020] (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.degree. C.
[0021] In accordance with another aspect of the present invention,
there is provided a method for plating a non-woven fabric with
metals through continuous electroless and electrolytic processes,
the method comprising:
[0022] (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.degree. 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.degree. C.
[0023] The present inventors searched and endeavored to develop a
method for preparing a metal-plated fiber nonwoven fabric with
excellent economical feasibility and conductivity, and as a result,
the present inventors verified that the adoption of the continuous
electroless and electrolytic surface treatment processes has
advantages in shortening of the process time, having price
competitiveness, and simplifying production facilities when
compared with only an electroless or electrolytic surface treatment
process of the conventional art, and induces not only dense plating
between metal structures, leading excellent conductivity, but also
low production costs, when compared with products of the
conventional art.
[0024] The method of the present invention is characterized in that
a fiber nonwoven fabric is first electroless-plated (with copper or
nickel) through surface treatment by a non-oxidation method and is
then electro-plated (with nickel), thereby minimizing the
production process and allowing continuous processes like
anodizing, thus preparing a high-functional nonwoven fabric with
relatively superior conductivity.
[0025] The method of the present invention is implemented in a
manner in which electroless copper plating or electroless nickel
plating is first performed, followed by electrolytic plating.
[0026] The method of the present invention may be applied to the
nonwoven fabric by various known preparing methods, and for
example, may be applied to a dry-laid nonwoven fabric, a wet-laid
nonwoven fabric, a spunbond nonwoven fabric, or the like. According
to an embodiment of the present invention, the method of the
present invention may be applied to a carbon fiber nonwoven fabric
or a PET nonwoven fabric, as a wet-laid nonwoven fabric. The
preparing methods of the above-described dry-laid nonwoven fabric,
wet-laid nonwoven fabric, or a spunbond nonwoven fabric are widely
known in the art, and Korean Patent Publication No.
10-2012-0121079, Korean Patent Registration No. 101049623, Korean
Patent Registration No. 101133851, and Korean Patent Registration
No. 101156844 are incorporated herein by reference.
[0027] The plating method of the present invention may be applied
to various kinds of nonwoven fabrics, for example, a nonwoven
fabric manufactured of 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.
[0028] The polyester fiber includes 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), and Vectran, but is not limited
thereto.
[0029] According to an embodiment of the present invention, the
method of the present invention may be applied to a carbon fiber
nonwoven fabric or a PET nonwoven fabric.
[0030] Meanwhile, the nonwoven fabric, to which the method of the
present invention is applied, may be manufactured by mixing the
foregoing fiber (referred to as "first fiber") with a second fiber
as a reinforcing fiber. The reinforcing fiber is a material for
increasing the strength of the nonwoven fabric, and is a
low-melting fiber or a low-melting filament, and for example, an
L/M polyester fiber (LMP) may be used. The low-melting polyester
fiber has a melting point lower than 255.degree. C., which is the
melting point of general polyester, and is used for the purpose of
thermal fusion.
[0031] According to the present invention, the low-melting fiber as
the second fiber is an L/M polyethylene terephthalate (low-melting
PET). The melting point of L/M polyethylene terephthalate is
relatively low, and thus, the L/M polyethylene terephthalate, when
heated and compressed at 100.degree. C., is melted and mixed with
the first fiber, thereby increasing the strength of the entire
nonwoven fabric.
[0032] The method for plating a nonwoven fabric with metals through
continuous electroless and electrolytic processes of the present
invention is ultimately for manufacturing a metal-plated nonwoven
fabric, and may be used with the same meaning as a method for
manufacturing a metal-plated nonwoven fabric through continuous
electroless and electrolytic processes.
[0033] Hereinafter, the method of the present invention for
manufacturing a metal-plated nonwoven fabric through continuous
electroless and electrolytic processes will be described by the
steps as below:
[0034] (a) Electroless Plating Process
[0035] First, a nonwoven fabric is electroless-plated with a
metal.
[0036] In one embodiment, in cases where the carbon fiber nonwoven
fabric is plated with copper, an electroless plating liquid
contains pure water, a copper metal salt, a complexing agent, a
reducing agent, a stabilizer, and a pH adjusting agent.
[0037] The copper metal salt contained in the electroless plating
liquid supplies copper ions to impart conductivity to carbon
fibers. Meanwhile, formalin as a reducing agent, EDTA as a
complexing agent, triethanolamine (TEA) and 2,2'-bipiridine as
stabilizers, and 25% NaOH as a pH adjusting agent were used.
[0038] As can be confirmed in examples, with the increase in the
concentrations of formalin as a reducing agent and NaOH as a pH
adjusting agent, which are contained in the electroless plating
liquid, the plating rate was increased, but the lifetime of the
plating liquid was shortened, and thus, considering this matter,
the contents of the reducing agent and the pH adjusting agent were
adopted.
[0039] Meanwhile, as can be clearly confirmed from examples, as a
result of testing the plating rate and the liquid stability by
adjusting the content of the reducing agent when the contents of
the copper ions and the complexing agent increase at the same
ratio, the plating rate and the thickness of the plating layer can
be controlled by adjusting the concentrations of copper ions and
formalin as a reducing agent, and through the control of the
thickness of the plating layer, the specific gravity, strength,
elastic modulus, and strain can be controlled. However, as the
plating layer is thicker, the specific gravity is increased, and
the strength, elastic modulus, and strain deteriorate, and thus the
present invention has solved the above problems by performing
electrolytic plating together with the adjustment of the
concentrations of the copper ions and formalin as a reducing agent,
thereby improving conductivity through a thin thickness. This is
why the present invention adopts continuous electroless and
electrolytic processes.
[0040] According to an embodiment of the present invention, the
electroless plating step in step (a) is characterized by allowing
the nonwoven fabric to pass through an electroless plating liquid
to plate the nonwoven 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.degree. C.
[0041] In another embodiment, in cases where the nonwoven fabric is
plated with nickel, the electroless plating liquid contains pure
water, a nickel metal salt, a pH buffer, a reducing agent, and a
stabilizer.
[0042] The nickel metal salt contained in the electroless plating
liquid supplies nickel ions to impart conductivity to the nonwoven
fabric, and NaH.sub.2PO.sub.2 as a reducing agent, potassium
thiosulfate as a stabilizer, and Na.sub.3C.sub.6H.sub.5O.sub.7 as a
pH buffer may be used.
[0043] After the electroless plating, three stages of washing are
conducted, and the third washing in the three stages of washing is
conducted by adding 1-2% H.sub.2SO.sub.4. This is for keeping the
pH of an electrolytic plating bath and activating surfaces of the
electroless-plated carbon fibers.
[0044] (b) Electrolytic Plating Process
[0045] After step (a), the copper or nickel electroless-plated
nonwoven fabric is continuously plated with nickel through an
electrolytic plating process.
[0046] Here, one of the characteristics of the present invention is
that the electrical conductivity of the fiber or nonwoven fabric is
improved by conducting an electroless plating process and then
conducting a nickel electrolytic plating process.
[0047] An electrolytic plating liquid for conducting the
electrolytic plating process employs Ni(NH.sub.2SO.sub.3).sub.2 and
NiCl.sub.2, as nickel metal salts, and H.sub.3BO.sub.3, as a pH
buffer.
[0048] As can be clearly confirmed from examples, the carbon fibers
obtained by continuous electroless and electrolytic processes
reduced the electric resistance value by about 32- to 37-fold
compared with non-plated carbon fibers, and reduced by 2-fold
compared with comparative examples, thereby improving electrical
conductivity. Therefore, it can be seen that even a nonwoven fabric
manufactured of carbon fibers had improved electrical
conductivity.
[0049] It is considered that the electrical conductivity was
improved in a manner in which, after electroless plating, copper or
nickel pores were filled by Ni electrolytic plating in a fast
time.
[0050] According to an embodiment of the present invention, the
electrolytic plating process in step (c) is conducted by applying a
constant voltage (CV) of 5-15 V.
[0051] In cases of continuous electroless copper plating and
electrolytic nickel plating processes, the electrolytic plating
process is conducted by applying a constant voltage (CV) of 5-10 V,
and more preferably 6-8 V.
[0052] In cases of continuous electroless nickel plating and
electrolytic nickel plating processes, the electrolytic plating
process is performed by applying a constant voltage (CV) of 10-15
V.
[0053] The advantage of the electroless and electrolytic plating
processes is that an alloy layer is formed that: exhibits excellent
electrical conductivity; is effective in adhesive strength and
ductility; and has excellent electrical conductivity even with a
thin thickness due to an electrolytic metal material adhering to
spaces of the metal, which are generated in the electroless
plating. In addition, the electroless and electrolytic plating
processes have an advantage in that a fiber or nonwoven fabric can
be uniformly plated.
[0054] Electroless (copper or nickel) plating is first conducted
and then electrolytic plating is continuously conducted while a
voltage is applied to a bath in which a nonwoven fabric is placed,
so that electrolyte ions are combined with pores generated from
electroless plating, thereby producing a product with a small
plating thickness and improved conductivity.
[0055] According to the present invention, the non-woven fabric in
step (a) may be pre-treated, before step (a), by a method including
the following steps:
[0056] (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;
[0057] (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;
[0058] (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
[0059] (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).
[0060] (i) Degreasing and Softening Carbon Fiber
[0061] As for the pretreatment of the nonwoven fabric in the method
of the present invention, the non-woven fabric is first degreased
and softened by allowing non-woven fabric to pass through an
aqueous solution containing a surfactant, an organic solvent, and a
non-ionic surfactant.
[0062] The aqueous solution containing a surfactant, an organic
solvent, and a non-ionic surfactant functions as a degreasing
action of removing epoxy or urethane that has been sized on the
carbon fibers, and at the same time, functions as an action of
softening surfaces of the fibers through swelling.
[0063] According to the present invention, the aqueous solution in
step (i) contains 15-35 wt % of a solution, as a surfactant, in
which pure water and NaOH are mixed at a weight ratio of
40-49:1-10, 50-80 wt % of diethyl propanediol and 5-15 wt % of
dipropylene glycol methyl ether as organic solvents, and 400-600
ppm of a non-ionic surfactant, and more preferably, contains 20-30
wt % of a solution, as a surfactant, in which pure water and NaOH
are mixed at a weight ratio of 45-48:2-5, 58-72 wt % of diethyl
propanediol and 8-12 wt % of dipropylene glycol methyl ether as
organic solvents, and 400-600 ppm of a non-ionic surfactant.
[0064] The non-ionic surfactant includes various non-ionic
surfactants known in the art, but the non-ionic surfactant is
preferably ethoxylated linear alcohol, ethoxylated linear
alkyl-phenol, or ethoxylated linear thiol, and more preferably,
ethoxylated linear alcohol.
[0065] According to still another preferable embodiment of the
present invention, step (i) was carried out at a temperature of
40-60.degree. C. for 1-5 minutes, and more preferably at a
temperature of 45-55.degree. C. for 1-3 minutes.
[0066] (ii) Etching Process
[0067] Then, an etching process is performed to neutralize strong
alkali components, assist a washing action for a next process, a
sensitizing process, and conduct a conditioning action.
[0068] An aqueous solution for the etching process contains sodium
bisulfate (NaHSO.sub.3), sulfuric acid (H.sub.2SO.sub.4), ammonium
persulfate ((NH.sub.4).sub.2S.sub.2O.sub.8), and pure water.
[0069] According to the present invention, the aqueous solution in
step (ii) contains 0.1-10 wt % of sodium bisulfate (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, and more preferably, contains 0.8-2 wt % of
sodium bisulfite (NaHSO.sub.3), 0.3-1 wt % of sulfuric acid
(H.sub.2SO.sub.4), 10-20 wt % of ammonium persulfate
((NH.sub.4).sub.2S.sub.2O.sub.8), and 77-88.9 wt % of pure
water.
[0070] According to an embodiment of the present invention, step
(ii) is performed at a temperature of 20-25.degree. C. for 1-5
minutes, and more preferably at a temperature of 20-25.degree. C.
for 1-3 minutes.
[0071] (iii) Sensitizing Process
[0072] Then, a sensitizing process is performed by allowing the
nonwoven fabric as the product in step (ii) to pass through an
aqueous solution of PdCl.sub.2.
[0073] The sensitizing process is for allowing metal ions to be
adsorbed on surfaces of the surface-modified fibers or nonwoven
fabric.
[0074] The concentration of the aqueous solution of PdCl.sub.2 is
more preferably 10-30%, and still more preferably 15-25%.
[0075] According to an embodiment of the present invention, step
(iii) is performed at a temperature of 20-40.degree. C. for 1-5
minutes, and more preferably at a temperature of 25-35.degree. C.
for 1-3 minutes.
[0076] (iv) Activating Process
[0077] Then, an activating process is performed by allowing the
nonwoven fabric as the product in step (iii) to pass through an
aqueous solution of sulfuric acid (H.sub.2SO.sub.4).
[0078] Herein, it has been described that the activating process is
performed after the sensitizing process, but the performing of the
activating process together with the sensitizing process is
included within the scope of the present invention.
[0079] The activating process is performed in order to remove
colloidized Sn, for the prevention of Pd oxidation.
[0080] More preferably, the concentration of the aqueous solution
of sulfuric acid (H.sub.2SO.sub.4) is 5-15%.
[0081] According to still another preferable embodiment of the
present invention, step (iv) is performed at a temperature of
40-60.degree. C. for 1-5 minutes, and more preferably at a
temperature of 45-55.degree. C. for 1-3 minutes.
[0082] The nonwoven fabric may be pre-treated by the
above-described method, and the pre-treated nonwoven fabric may be
plated with metals, copper and nickel, or nickel and nickel, by
continuous electroless and electrolytic processes. Meanwhile, it
has been described that the pre-treatment process is performed
after the nonwoven fabric is manufactured, but the pre-treatment of
the fibers per se may be applied before the nonwoven fabric is
manufactured.
[0083] According to still another aspect of the present invention,
the present invention provides a metal (copper and nickel)-plated
nonwoven fabric manufactured by the method of the present
invention.
[0084] According to another aspect of the present invention, the
present invention provides a metal (nickel and nickel)-plated
nonwoven fabric manufactured by the method of the present
invention.
[0085] Since the nonwoven fabric plated with copper and nickel or
nickel and nickel of the present invention is manufactured by the
foregoing method for manufacturing metal-plated carbon fibers using
continuous electroless and electrolytic processes of the present
invention, the overlapping descriptions therebetween are omitted to
avoid excessive complexity of the specification due to repetitive
descriptions thereof.
Advantageous Effects
[0086] Features and advantages of the present invention are
summarized as follows:
[0087] (a) The plating method used in the present invention allows
continuous processes and achieves stable treatment, and at the same
time, allows fibers or nonwoven fabric to have high electrical
conductivity by introducing a copper-nickel alloy or nickel-nickel
metal onto surfaces of carbon fibers.
[0088] (b) Furthermore, when a composite material is prepared using
such fibers or nonwoven fabric, there is no separation between the
carbon fibers and the copper-nickel plating or nickel-nickel
plating at the time of product molding, and thus the same
conductivity is maintained upon the completion of the composite
material. Therefore, unlike conventional products, the present
composite can reduce the process and costs for adding a conductive
fiber for the purpose of increasing electrical conductivity, and
has no problems in mechanical property, which is one of the
important features of the composite material.
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.degree. C., thereby
manufacturing a nonwoven fabric. L/M PET can be melted at about
100.degree. 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.degree. 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.degree. 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.degree. 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.degree. 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.degree. 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.degree. 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.degree. 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.degree. 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.degree. 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.degree. 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.degree. 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.degree. 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 (.OMEGA./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) (.OMEGA./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.degree. 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.degree. 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 (.mu.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.degree. 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.degree. 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 .mu.m or more). For a plating
thickness of 0.3 .mu.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 (.mu.m) 7.5 7.828 7.705 -- Tex (Fiber
thickness) 1420 1575 1561 -- Electrical resistance (.OMEGA./m) --
0.8 0.7 -- Electrical resistance (.OMEGA.cm) 7.5 .times. 10.sup.-5
4.62 .times. 10.sup.-5 4.05 .times. 10.sup.-5 -- Electrical
resistance -- 32-Fold 37-Fold General CF: compared with general CF
reduction redution 1.50 .times. 100.sup.-3 .OMEGA.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.degree. 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.degree. 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.degree. 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.degree. 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) (.OMEGA.) (.OMEGA./square)
(.OMEGA.*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) (.OMEGA.) (.OMEGA./square)
(.OMEGA.*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.
* * * * *