U.S. patent application number 11/887781 was filed with the patent office on 2009-10-08 for pre-treatment method for plating and instrument for waterworks of lead-contained copper alloy.
Invention is credited to Mitsuo Imamoto, Masashi Kawamoto, Yuichi Takamatsu.
Application Number | 20090250354 11/887781 |
Document ID | / |
Family ID | 38723336 |
Filed Date | 2009-10-08 |
United States Patent
Application |
20090250354 |
Kind Code |
A1 |
Takamatsu; Yuichi ; et
al. |
October 8, 2009 |
Pre-Treatment Method for Plating and Instrument for Waterworks of
Lead-Contained Copper Alloy
Abstract
A pre-treatment method for plating wherein lead or the like
dissolved in an etching liquid is not electro-deposited
(re-adhesion) on a lead-contained copper alloy to be plated even
without adding a chelating agent forming an insoluble inert
combined substance. The lead-contained copper alloy to be plated is
dipped in an alkaline etching liquid without adding a chelating
agent which would form an insoluble inert combined substance. In
this state, electrolysis where the lead-contained copper alloy
functions as one of a positive electrode and a negative electrode,
and electrolysis where the lead-contained copper alloy functions as
the other of the positive electrode and the negative electrode are
performed alternately (PR electrolysis).
Inventors: |
Takamatsu; Yuichi; (Fukuoka,
JP) ; Kawamoto; Masashi; (Fukuoka, JP) ;
Imamoto; Mitsuo; (Fukuoka, JP) |
Correspondence
Address: |
CARRIER BLACKMAN AND ASSOCIATES
43440 WEST TEN MILE ROAD, EATON CENTER
NOVI
MI
48375
US
|
Family ID: |
38723336 |
Appl. No.: |
11/887781 |
Filed: |
May 21, 2007 |
PCT Filed: |
May 21, 2007 |
PCT NO: |
PCT/JP2007/060330 |
371 Date: |
October 3, 2007 |
Current U.S.
Class: |
205/215 |
Current CPC
Class: |
C25F 3/02 20130101; C25D
5/34 20130101 |
Class at
Publication: |
205/215 |
International
Class: |
C25D 5/34 20060101
C25D005/34 |
Foreign Application Data
Date |
Code |
Application Number |
May 22, 2006 |
JP |
2006 140990 |
Claims
1. A plating pre-treatment method for plating of preliminarily
removing lead existing on a surface layer of a lead-contained
copper alloy prior to carrying out plating on the surface,
comprising the steps of: alternately performing electrolysis where
said lead-contained copper alloy functions as one of a positive
electrode and a negative electrode, and electrolysis where said
lead-contained copper alloy functions as the other of the positive
electrode and the negative electrode, the steps being performed in
a state where said lead-contained copper alloy is dipped in an
alkaline etching liquid.
2. The pre-treatment method for plating according to claim 1,
wherein said lead-contained copper alloy functions as the positive
electrode in a last-performed one of said electrolysis steps.
3. The pre-treatment method for plating according to claim 1,
wherein the electrolysis steps are performed with conditions of an
electric current density of 1 A/dm.sup.2 r more and 25 A/dm.sup.2
or less and a current reversing period of 2 seconds or more and 30
seconds or less.
4. The pre-treatment method for plating according to claim 1, said
alkaline etching liquid contains an oxidizing agent.
5. The pretreatment method for plating according to claim 1,
wherein nickel plating is carried out and thereafter chromium
plating is carried out as said plating on the surface of the
lead-contained copper alloy after said electrolysis steps.
6. A plating pre-treatment method for a surface of an instrument
for waterworks of a lead-contained copper alloy comprising the
steps of: alternately performing electrolysis where said
lead-contained copper alloy functions as one of a positive
electrode and a negative electrode, and electrolysis where said
lead-contained copper alloy functions as the other of the positive
electrode and the negative electrode, the steps being performed in
a state where said lead-contained copper alloy is dipped in an
alkaline etching liquid.
7. The plating pre-treatment method according to claim 6, wherein
in the electrolysis performed alternately with the positive
electrode and the negative electrode, said lead-contained copper
alloy functions as the positive electrode in a last-performed one
of the electrolysis steps.
8. The plating pre-treatment method according to claim 6, wherein
the electrolysis steps are performed with conditions of an electric
current density of 1 A/dm.sup.2 or more and 25 A/dm.sup.2 or less
and a current reversing period of 2 seconds or more and 30 seconds
or less
9. The plating pre-treatment method according to claim 6, wherein
said alkaline etching liquid contains an oxidizing agent.
10. The pre-treatment method for plating according to claim 2,
wherein the electrolysis steps are performed with conditions of an
electric current density of 1 A/dm.sup.2 or more and 25 A/dm.sup.2
or less and a current reversing period of 2 seconds or more and 30
seconds or less.
11. The pre-treatment method for plating according to claim 2, said
alkaline etching liquid contains an oxidizing agent.
12. The pre-treatment method for plating according to claim 2,
wherein nickel plating is carried out and thereafter chromium
plating is carried out as said plating on the surface of the
lead-contained copper alloy after said electrolysis steps.
13. The plating pre-treatment method according to claim 7, wherein
the electrolysis steps are performed with conditions of an electric
current density of 1 A/dm.sup.2 or more and 25 A/dm.sup.2 or less
and a current reversing period of 2 seconds or more and 30 seconds
or less
14. The plating pre-treatment method according to claim 7, wherein
said alkaline etching liquid contains an oxidizing agent.
Description
TECHNICAL FIELD
[0001] The present invention relates to a pre-treatment method for
plating of preliminarily removing lead existing on a surface layer
of a lead-contained copper alloy prior to carrying out the plating
on a surface of the lead-contained copper alloy and to an
instrument for waterworks of the lead-contained copper alloy
obtained by the application of the pre-treatment method for
plating.
BACKGROUND ART
[0002] As a material for an instrument for waterworks there is
generally used a lead-contained copper alloy which is superior in
workability and protection against corrosion. Since this
lead-contained copper alloy contains lead harmful to the human
health, plating is carried out on a surface of the alloy in a
process step as shown in FIG. 3 so as to prevent the lead from
being eluted out.
[0003] To put it concretely, the lead-contained copper alloy is
dipped in an alkaline etching liquid as a pre-treatment to remove
the lead from a surface layer of the lead-contained copper alloy.
Then, after carrying out nickel plating, chromium plating and
chromate treatment, the lead-contained copper alloy is washed.
[0004] The above pre-treatment is the treatment for removing stains
on the surface so as to facilitate the formation of a plated layer
and for preventing the elution of lead. The applicant of the
present invention paid attention to a characteristic that lead is
amphoteric metal and proposed the method of removing lead by both
of alkali and acid by adding an oxidizing agent to the alkaline
etching liquid (see patent reference 1).
[0005] Further, there is known an alkaline electrolytic cleaning
method of removing the stains on the surface by electrolysis while
dipping the lead-contained copper alloy in the alkaline etching
liquid. As an electrolysis method there are cathode electrolysis
that the lead-contained copper alloy functions as a negative
electrode and anode electrolysis that the lead-contained copper
alloy functions as a positive electrode. In the anode electrolysis,
oxygen gas is generated on the surface of the lead-contained copper
alloy so as to decompose and remove organic stains on the surface
of the lead-contained copper alloy by the gas, so that it is
superior in cleaning effect. However, since the lead-contained
copper alloy is dissolved by the electrical operation (etching),
roughness (over-etching) of a basis material is apt to occur in the
lead-contained copper alloy. Therefore, there is also used the
cathode electrolysis method that dissolution of the lead-contained
copper alloy does not occur and hydrogen gas is generated on the
surface of the lead-contained copper alloy. A PR (periodic reverse)
electrolysis method that repeats the cathode electrolysis and the
anode electrolysis alternately is also known.
[0006] In the case where the cathode electrolysis method is
selected for the pre-treatment for plating of the lead-contained
copper alloy, since the object to be plated (the lead-contained
copper alloy) becomes the negative electrode, electro-positively
charged ions such as lead (Pb.sup.+) dissolved in the alkaline
etching, heavy metals contained as impurities in the etching
liquid, etc. are electro-deposited (the same operation as plating)
on and re-adhered to the surface of the plated object by the
electrical operation.
[0007] This re-adhesion causes adherence failure in the following
plating and tarnish after the plating. Therefore, there is proposed
a method in which a chelating agent which forms an insoluble inert
combined substance is added to the alkaline etching liquid and an
insoluble chelating compound is formed by having the lead dissolved
in the alkaline etching, etc. reacted on the chelating agent so as
to remove the insoluble chelating compound by precipitating it
before being electro-deposited on the surface of the plated object
(see patent reference 2).
[0008] Patent reference 1: Japanese patent No. 3182765.
[0009] Patent reference 2: Japanese patent application publication
No. H02-274900.
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0010] In the method of adding the oxidizing agent to the alkaline
etching liquid to remove lead as disclosed in patent reference 1,
there may be cases degreasing power is not sufficient because of
being not dependent on the electrolysis. Also, in a case where a
chelating agent forming an insoluble inert combined substance is
added to the alkaline etching liquid when carrying out the cathode
electrolytic cleaning in the state that the lead-contained copper
alloy is dipped in the alkaline etching liquid as disclosed in
patent reference 2, the electro-deposition (re-adhesion) can be
prevented but the degreasing power may be insufficient merely by
the application of the cathode electrolysis. Further, the addition
of the chelating agent incurs an increase in costs for that.
Means for Solving the Problem
[0011] To solve the above mentioned problem, a pre-treatment method
for plating, according to the present invention, of preliminarily
removing lead existing on a surface layer of a lead-contained
copper alloy prior to carrying out nickel plating or chromium
plating on a surface of the lead-contained copper alloy, comprising
the step of performing electrolysis where the lead-contained copper
alloy functions as one of a positive electrode and a negative
electrode, and electrolysis where the lead-contained copper alloy
functions as the other of the positive electrode and the negative
electrode alternately (PR electrolysis) in a state where the
lead-contained copper alloy is dipped in an alkaline etching
liquid.
[0012] In the PR electrolysis it is preferable that the
lead-contained copper alloy functions as a positive electrode at
the end. Also, as conditions of the PR electrolysis it is
preferable that electric current density is 1 A/dm.sup.2 or more
and 25 A/dm.sup.2 or less and a current reversing period is 2
seconds or more and 30 seconds or less. Further, it is also
preferable that an oxidizing agent is added to the alkaline etching
liquid.
[0013] Also, an instrument for waterworks of lead-contained copper
alloy, according to the present invention, a surface of which is
plated, wherein as pre-treatment for plating, treatment of
alternately carrying out electrolysis that the lead-contained
copper alloy functions as one of a positive electrode and a
negative electrode and electrolysis that the lead-contained copper
alloy functions as the other of the positive electrode and the
negative electrode is performed in such a state that the
lead-contained copper alloy is dipped in an alkaline etching
liquid.
[0014] In the PR electrolysis being performed when obtaining the
instrument for waterworks of the lead-contained copper alloy, it is
preferable that lastly the lead-contained copper alloy is the
positive electrode in the same way as above. Also, as conditions of
the PR electrolysis it is preferable that electric current density
is 1 A/dm.sup.2 or more and 25 A/dm.sup.2 or less and a current
reversing period is 2 seconds or more and 30 seconds or less.
Further, it is also preferable that an oxidizing agent is added to
the alkaline etching liquid.
EFFECTS OF THE INVENTION
[0015] According to the pre-treatment method for plating of the
present invention, lead or the like dissolved in the etching liquid
is not electro-deposited on or re-adhered to the lead-contained
copper alloy to be plated and the degreasing cleaning is
sufficiently carried out, so that defects such as tarnish or the
like are not caused on the surface after plating. Moreover, no
chelating agent which forms an insoluble inert combined substance
is used whereby costs can be efficiently decreased.
[0016] Further, in the last electrolysis of the PR electrolysis the
lead-contained copper alloy to be plated is the positive electrode,
so that it is possible to effectively prevent the
electro-deposition (re-adhesion) of lead or the like on the surface
of the plated object. Furthermore, when the oxidizing agent is
added to the alkaline etching liquid in the case of carrying out
the PR electrolysis, lead can be removed well due to a
characteristic that the lead is the amphoteric metal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a flow chart of plating to which pre-treatment for
plating of the present invention is applied;
[0018] FIG. 2 is a schematic view of PR electrolysis; and
[0019] FIG. 3 is an explanatory view showing a conventional plating
process.
MODE FOR CARRYING OUT THE INVENTION
[0020] An embodiment of the present invention will now be explained
with reference to the accompanying drawings. FIG. 1 is a flow chart
of plating to which pre-treatment for plating of the present
invention is applied, and FIG. 2 is a schematic view of PR
electrolysis. In the present invention, when ultra-sonic cleaning
and alkaline cleaning is carried out as pre-treatment for plating,
PR electrolysis is simultaneously carried out so as to accurately
remove stains on a surface of an object (a lead-contained alloy) to
be plated. Herein, the ultra-sonic cleaning is not necessarily
required, but the application of the PR electrolysis only using the
alkaline cleaning liquid may be enough. Meanwhile, following the PR
electrolysis using the alkaline cleaning liquid, cathode
electrolysis and anode electrolysis may be used solely or in
combination as the need arises. Then, the surface of the object
(the lead-contained alloy) to be plated is further cleaned thereby
to increase adhesiveness of the plating.
[0021] A concrete experiment is performed on the plating
adhesiveness and the quality of an external appearance by the PR
electrolysis without adding a chelating agent which forms an
insoluble inert combined substance. Conditions and results of the
experiment will be described hereunder. Herein, the object to be
plated is a single water faucet of bronze casting.
(Electrolytic Degreasing Conditions, Conditions of Electrolytic
Liquid) Alkaline Etching Liquid (Alkaline Cleaning)
(1) Main Component:
[0022] A plating process generally comprises a degreasing step and
a plating step. The degreasing step is the one for removing stains
such as oil components, etc. adhered to a base material. The main
components of alkaline etching liquid used in the present invention
are sodium hydroxide, potassium hydroxide, sodium carbonate, sodium
phosphate, sodium tripolyphosphate, sodium meta-silicate, sodium
ortho-silicate and the like, and when processing, an alkaline
solution in which one or more kinds of these components are
dissolved is used. The concentration is generally from several g/L
to several 10 g/L. It is to be judged properly by the combination
of the components to be used.
(2) Surface Active Agent:
[0023] The surface active agent is added with a view to decreasing
surface tension of the liquid so as to improve penetration and
wettability of the alkaline etching liquid. As the surface active
agent, an anionic surface active agent or a nonionic surface active
agent is mostly used and each of these surface active agents is
used solely or in combination. As the anionic surface active agent
there are given higher fatty acid sodium, sulfated oil, higher
alcohol sodium ester sulfate, sodium alkyl benzene sulfate, higher
alkyl ether sodium ester sulfate and sodium .alpha.-olefin sulfate.
Further, as the nonionic surface active agent there are given alkyl
polyoxyethylene ether, alkyl phenyl polyoxyethylene ether, a fatty
acid ethylene oxide addition product and a polypropylene glycol
ethylene oxide addition product (pluronic). The addition volume is
generally from several g/L to several 10 g/L.
(3) Chelating Agent:
[0024] The chelating agent may be added in order for preventing a
hydroxide of lead from re-adhesion and at the same time for
accelerating the dissolution of lead. As the chelating agent there
are preferable such compounds as EDTA, ethylenediamine,
triethanolamine, thiourea, Rochelle salt, tartaric acid and the
like which are apt to form a complex with lead. It is preferable
that the concentration of each component is from several g/L to
several 10 g/L.
[0025] The chelating agent which forms the insoluble inert product
with heavy metal such as lead may be added. As the chelating agent
which forms the insoluble inert product, sodium dimethyl
dithiocarbamate, sodium diethyl dithiocarbamate and the like are
preferable. It is also preferable that the concentration of each
component is from several g/L to several 10 g/L.
(4) Oxidizing Agent
[0026] In a case of adding the oxidizing agent to the alkaline
etching liquid, lead is oxidized and dissolved via lead oxide (PbO,
etc.) in alkali, so that the dissolution of lead is accelerated. As
the oxidizing agent, there are used organic oxidizing compounds
such as sodium methanitro benzene sulfonate, sodium paranitro
benzoate and the like, and inorganic compounds such as
hypochlorite, bleaching powder, hydrogen peroxide, potassium
permanganate, peroxosulfate, perchlorate and the like. It is
preferable that the concentration of each component is from several
g/L to several 10 g/L.
(Conditions of Plating)
[0027] The performed plating is as follows.
(1) Chrome Plating
[0028] As a chrome plating bath, a publicly well-known Sargent bath
comprised of absolute chromic acid and sulfuric acid can be used.
It is also possible to use a chrome fluoride plating bath replacing
a part or the whole of sulfuric acid in the Sargent bath with
fluoride may be used. When carrying out the chrome plating in the
chrome plating liquid, an outer surface is chrome plated while, in
an inner surface, lead is dissolved with the dissolution of the
entire copper alloy material due to the strong oxidizing property
of the chrome plating liquid. In the case of no existence of the
fluoride, there is some possibility that a precipitate remains as
lead chromate. In this respect, since the fluoride has the function
of dissolving the precipitate, it is preferable to carry out the
chrome plating in the chrome fluoride plating bath. Then,
preferably, the temperature is from 40 degrees centigrade to 60
degrees centigrade and the dipping period is from several 10
seconds to several minutes.
[0029] As the fluoride, it is possible to use almost all of
fluorine compounds such as sodium fluoride, potassium fluoride,
ammon fluoride, hydrofluoric acid, fluoroboric acid, silicofluoric
acid, sodium silicofluoride, potassium silicofluoride, chrome
fluoroborate and the like.
(2) Chromate Filming
[0030] An additive to be used in the chromate filming is based on
an absolute chromic acid, a phosphoric acid and a sulfuric acid. As
the case may be, it is possible to add or be replaced with a nitric
acid, a hydrofluoric acid, an acetic acid, an oxalic acid, chromate
and the like. A chromate solution for use in galvanizing, etc on
the market may be used.
[0031] It is preferable that the concentration of each component is
from several g/L to several 10 g/L. Also it is preferable that the
temperature for treatment is from an ordinary temperature to 60
degrees centigrade and the period for treatment is from several
seconds to several minutes. The product on the outer surface of
which the plating is carried out is dipped in the chromate liquid,
so that a chromate film is formed in the inner surface thereof so
as to prevent the elution of lead. When adding the phosphoric acid
to the absolute chromic acid which is a main component of the
chromate liquid, the lead elution is more effectively prevented in
a synergistic effect.
(Evaluation Test)
[0032] After carrying out the above mentioned electrolytic
degreasing and the plating (after nickel plating, chrome plating
and chromate filming are done in turn), the following evaluation
test is performed.
(1) Adhesiveness Test
[0033] "21.2 Thermal shock test" of "JIS (Japanese Industrial
Standards) H8504 Plating adhesiveness test method" (test method for
examining plating adhesiveness by thermal shock of heating and
quenching specimen) was performed. As a result, as shown in Table 1
below, there is no problem in adhesiveness other than the cathode
electrolysis without a chelating agent which forms an insoluble
inert combined substance.
TABLE-US-00001 TABLE 1 Cathode Anode PR electrolysis electrolysis
electrolysis Without chelating agent NG OK OK With chelating agent
OK OK OK
(2) External Appearance Test
[0034] "9.2 External appearance test" of "JIS H8617 Nickel plating
and nickel-chrome plating" wherein the external appearance test is
performed by visual evaluation and whether or not there are plating
defects such as roughness, burnt deposits, cracking, pit, exposure
of base material, etc., a sign of adhesive failure, a dirty mark, a
stain and the like is examined. As a result, as shown in Table 2
below, only the PR electrolysis achieved good results without
adding a chelating agent which forms an insoluble inert combined
substance.
TABLE-US-00002 TABLE 2 Cathode Anode PR electrolysis electrolysis
electrolysis Without chelating agent NG NG OK (present invention)
With chelating agent OK NG OK
[0035] Next, with respect to the anode electrolysis and the PR
electrolysis, experiments on the adhesiveness and the external
appearance were performed under the following experimental
conditions.
[0036] First, Table 3 shows experimental results of the anode
electrolysis with a chelating agent which forms an insoluble inert
combined substance. As the experimental results, the adhesiveness
was good in all the experiments, but the external appearance was
not good in all the experiments. Herein, as the electrolytic
conditions, after ultra-sonic cleaning for one minute by
application of ultrasonic waves, the alkaline cleaning was carried
out for two minutes.
TABLE-US-00003 TABLE 3 Ultrasonic Alkaline External cleaning
cleaning Remarks Appearance Anode 1 A/dm.sup.2 1 A/dm.sup.2
Ultrasonic waves NG elec- only 2'' on 2'' off trolysis 0.5
A/dm.sup.2 0.5 A/dm.sup.2 Ultrasonic waves NG only 2'' on 2'' off 0
A/dm.sup.2 1 A/dm.sup.2 No electrolysis by NG ultrasonic waves 0
A/dm.sup.2 5 A/dm.sup.2 No electrolysis by NG ultrasonic waves
[0037] Table 4 shows experimental results of the anode electrolysis
without a chelating agent which forms an insoluble inert combined
substance. As the experimental results, the adhesiveness was good
in all the experiments, but the external appearance was not good in
all the experiments. Herein, as the electrolytic conditions, after
ultra-sonic cleaning for one minute by application of ultrasonic
waves, the alkaline cleaning was carried out for two minutes.
TABLE-US-00004 TABLE 4 Pre-treatment conditions Ultrasonic
Ultrasonic Alkaline Alkaline External appearance quality cleaning
pulse cleaning pulse Gloss Irregularities 0 A/dm.sup.2 -- 1
A/dm.sup.2 -- NG NG 0 A/dm.sup.2 -- 10 A/dm.sup.2 -- NG NG 0
A/dm.sup.2 -- 10 A/dm.sup.2 2'' on 2'' off Very bad NG 2.5
A/dm.sup.2 1'' on 3'' off 10 A/dm.sup.2 -- NG NG 2.5 A/dm.sup.2 1''
on 3'' off 1 A/dm.sup.2 (80.degree. C.) -- NG NG 2.5 A/dm.sup.2 1''
on 3'' off 10 A/dm.sup.2 (80.degree. C.) -- NG NG 2.5 A/dm.sup.2 --
10 A/dm.sup.2 -- NG Very bad 2.5 A/dm.sup.2 -- 2.5 A/dm.sup.2 -- NG
Very bad
[0038] Table 5 shows experimental results of the PR electrolysis
without a chelating agent which forms an insoluble inert combined
substance. The adhesiveness and the external appearance were both
good in all the experiments. Herein, as the electrolytic
conditions, after ultra-sonic cleaning for one minute by
application of ultrasonic waves, the alkaline cleaning was carried
out for two minutes.
TABLE-US-00005 TABLE 5 PR electrolysis (Reversing period: 2''
.revreaction. 2'') Quality evaluation (N = 3) Ultrasonic Alkaline
External appearance cleaning cleaning Adhesiveness inspection 0
A/dm.sup.2 2 A/dm.sup.2 OK OK 5 A/dm.sup.2 OK OK 10 A/dm.sup.2 OK
OK 1 A/dm.sup.2 2 A/dm.sup.2 OK OK 5 A/dm.sup.2 OK OK 10 A/dm.sup.2
OK OK 3 A/dm.sup.2 2 A/dm.sup.2 OK OK 5 A/dm.sup.2 OK OK 10
A/dm.sup.2 OK OK
[0039] From the above experiments, it became clear that in the case
of application of the PR electrolysis, the adhesiveness and
external appearance after plating are good even without adding a
chelating agent which forms an insoluble inert combined substance.
Therefore, next, experiments on preferable conditions (a reversing
period and current density) of the PR electrolysis were performed.
In the experiments, the ultra-sonic cleaning was carried out for
one minute by application of ultrasonic waves, and thereafter, the
alkaline cleaning was carried out for two minutes.
[0040] The results are shown in Table 6 below. From Table 6, it
becomes clear that a preferable current reversing period is 30
seconds or less and a preferable current density is 25 A/dm.sup.2
or less.
TABLE-US-00006 TABLE 6 Electrode at the end Current Negative
Positive Positive Positive Positive Positive Positive reversing
electrode electrode electrode electrode electrode electrode
electrode period 2'' 2'' 5'' 5'' 10'' 10'' 20'' 20'' 30'' 30'' 45''
45'' 60'' 60'' 1 A/dm.sup.2 OK OK OK OK OK NG NG 3 A/dm.sup.2 OK OK
OK OK OK NG NG 5 A/dm.sup.2 OK OK OK OK OK NG NG 10 A/dm.sup.2 OK
OK OK OK OK NG NG 20 A/dm.sup.2 OK OK OK OK OK NG NG 25 A/dm.sup.2
OK OK OK OK OK NG NG 30 A/dm.sup.2 NG NG NG NG NG NG NG
[0041] From the above, in the case of the PR electrolysis, the
plating adhesiveness and the external appearance were ensured even
without a chelating agent forming an insoluble inert combined
substance. Therefore, next, whether or not the lead elution meets
NSF standard and JIS standard was confirmed. A single lever water
faucet of bronze casting was used as a sample.
NSF Standard
[0042] The concentration of eluted lead was analyzed with respect
to the above sample which had undergone a treatment of
NSF/ANSI61-2003e "9 Mechanical plumbing devices."
[0043] Standard: 11 ppb or less after conversion
JIS Standard
[0044] The concentration of eluted lead was analyzed with respect
to the above sample which had undergone a treatment of JIS S3200-7
(2004) "Instruments for waterworks--Leaching performance test
method."
[0045] Standard: 7 ppb or less after conversion
[0046] Results of experiments are shown Table 7-1 and Table 7-2
below. As apparent from Table 7-1 and Table 7-2, the results of the
product obtained by the plating method to which the pre-treatment
for plating of the present invention was applied meet NSF standard
and the JIS standard.
TABLE-US-00007 TABLE 7-1 NSF standard test results Leaching value
Correction value NSF 1 13.72 3.16 NSF 2 14.23 3.27 NSF 3 13.68 3.15
Content volume: 230 ml Unit: ppb Correction value = Leaching value
x (Content volume/1000)
TABLE-US-00008 TABLE 7-2 JIS standard test results Leaching value
Correction value JIS 1 16.39 3.77 JIS 2 12.58 2.89 JIS 3 13.07 3.01
Content volume: 230 ml Unit: ppb Correction value = Leaching value
x (Content volume/1000)
* * * * *