Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PROCESS FOR METALLIZING A PLASTIC SURFACE
Description
The invention concerns a process for the metallizing of a plastic surface.
Within the
scope of the process, in accordance with the invention, the plastic surface of
a plastic article
or the plastic surfaces of several plastic articles are metallized.
On the one hand, metallized plastics are used for decorative purposes, for
example in
the sanitary facilities field or in the manufacture of automobiles. On the
other hand, metalli-
zation of plastics also occurs in connection with the surface treatment of
electronic compo-
nents for the purpose of electronic shielding. Especially the surfaces of
plastics, such as ac-
rylnitrile-butadiene-styrene (ABS) and possibly ABS-Polycarbonate blends are
metallized
for decorative purposes.
In an already known process in practice, the plastic surface is first
roughened by
strong etching, for example with chromic acid or chrome-hydrochloric acid. By
surface
roughening is meant especially that, due to the etching process, micro-caverns
are created in
the plastic surface. These micro-caverns, in general, have a size on the order
of .1 to 10 Vim.
Especially, these micro-caverns show a depth (i.e. an extent from the plastic
surface toward
the interior) in the range of .1 to 10 ~tm. The etching takes place at
relatively high tempera-
tures and, as a rule, for relatively extended periods. The concentration of an
oxidizer added to
the etching solution normally is relatively high. The roughening of the
plastic surface has the
purpose of allowing the subsequently to be applied activating layer and/or
metal layer to al-
most hook into the roughened plastic surface. The adhesion of a metal layer to
the roughened
plastic surface is achieved almost in the manner of the snap fastener
principle in this known
process. After the etching or roughening of the plastic surface, the surface
first is activated
with colloidal palladium or ionogene palladium. This activation, in the case
of the colloidal
process, is followed by a removal of a protective tin colloid or, in the case
of the ionogene
process, a reduction to the elemental palladium. Subsequently, copper or
nickel is chemically
deposited on the plastic surface as a conducting layer. Following this,
galvanizing or metal-
lizing, respectively, takes place. In practice, this direct metallizing of the
plastic surface
works only for certain plastics. If sufficient roughening of the plastic, or
the formation of
suitable micro-caverns, respectively, is not possible by etching the plastic
surface, a func-
tionally secure adherence of the metal layer to the plastic surface is not
guaranteed. There-
fore, in the case of the known process, especially the number of plastics
capable of being
coated is greatly limited. The direct metallization in accordance with this
known process
generally only functions without problems with ABS plastic parts. In the case
of ABS-
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Polycarbonate blends and polypropylene, metallization is only possible under
certain work-
ing conditions. In view of this, this known process is capable of improvement.
In the case of another known process ("New methods of electroless plating and
direct
electroplating of plastics", A. Vaskelis et al., Institute of Chemistry, A
Gostauto 9, 2600 Vil-
5 nius, Lithuania, paper to be presented the INTERFINISH 96 WORLD CONGRESS,
Interna-
tional Convention Centre, Birmingham, England, 10-12 September 1996), the
plastic surface
likewise is roughened by relatively heavy or strong etching, respectively.
Here also micro-
caverns are created in the plastic surface by etching in which the metal layer
to be applied is
mechanically anchored or hooked into. Also, the etching occurs at elevated
temperatures in
this process. The etching solution generally has a high concentration of an
oxidizer. The
plastic surface, pre-treated in this manner, subsequently is treated with a
copper salt solution,
and afterward it is treated with a second solution, containing sulfide ions or
polysulfide ions.
In this manner, an electrically conducting layer of non-stochiomeric copper
sulfide is created
on the plastic surface. The initial step of this known process is followed by
the treatment of
the plastic surface with both of the cited solutions at room temperature for a
duration of
maximally 1 minute. Even with this first step, only certain plastics can be
metallized in a
somewhat functionally secure and satisfactory manner. - After a second step of
this known
process, the treatment with both of the cited solutions takes place at a
higher temperature of
70 to 90°C, and for a longer period of 5 to 15 minutes. With this
working process it is in-
tended that both sulfur and also copper ions penetrate the plastic surface
into the plastic, and
that non-stoichiometric copper sulfide is also generated under the plastic
surface. In this
manner, especially good adhesion of the subsequently applied metal layer is to
be achieved.
However, the penetration described takes place only in a very incomplete
manner, and thus
the adhesion of the metal layer also leaves something to be desired. In
addition, also with this
process only certain plastics can be metallized in a satisfactory manner.
In practice, there further are several processes known whereby after the
etching of
the plastic surface and the formation of micro-caverns, the plastic surface is
treated with a
copper salt solution. Subsequently, a treatment with a sulfide solution is
applied. All these
processes are characterized by the disadvantage that in order to create a
somewhat satisfac-
tory metal layer, the process steps mentioned must be repeated several times
in sequence. It
is understood that this is complex and expensive.
In contrast, the invention is based on the technical problem to describe a
process of
the type mentioned in the beginning by which, in a less complex manner, a
large variety of
plastics can be metallized in a functionally secure and reproducible manner,
whereby they
are provided with a metal layer which meets.all requirements.
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To solve this technical problem, the invention describes a process for
metallizing a
plastic surface, whereby the following process steps are performed in
sequence:
1.1) The plastic surface is subjected to etching under mild conditions.
1.2) Subsequently, the plastic surface is treated with a metal salt solution
which
comprises at least one salt of the group "Cobalt salt, silver salt, tin salt,
lead salt".
1.3) The plastic surface is treated with a sulfide solution.
1.4) Finally, the plastic surface is metallized in a metallizing bath.
Additional process steps, especially rinsing steps, may be interspersed with
the proc-
ess steps which are the subject of the invention.
The mild etching referred to in the invention means especially that the
"etching", or
the treatment of the plastic surface, respectively, with a etching solution
occurs at low tem-
peratures and/or within a shorter time period at low concentration of the
etching solution. As
a matter of principle, mild etching conditions can be realized already when
one of the pre-
ceding three conditions is met. The low temperature referred to in the
invention means a
maximum temperature of 40°C. When the mild etching conditions are
created by a low tem-
perature, this is usefully a maximum of 30°C, with a temperature of
between 15°C and 25°C
being preferred. With the low temperatures mentioned above, the pre-treatment
with the
etching solution takes place especially over a time period of 3 to 15 minutes,
preferably 5 to
15 minutes and even more preferred 5 to 10 minutes. The invention claims that
the treatment
period is the shorter the higher the temperature. However, mild etching
conditions can be
also achieved at temperatures in excess of 40°C if the treatment period
selected is appropri-
ately short. According to one version of the invention, the etching treatment
takes place at
temperatures of 40°C to 95°C, preferably 50°C to
70°C, for a treatment period of 15 seconds
to 5 minutes, preferably .5 to 3 minutes. Here also, the invention claims that
the treatment
period is the shorter the higher the process temperature. In practical terms,
the process tem-
perature and/or process time is selected in accordance with the type of the
etching solution
employed.
Mild etching as specified in the invention also means that, contrary to the
known
processes referred to above, a roughening of the plastic surface, or the
creation of micro-
caverns in the plastic surface, respectively, does not occur. The micro-
caverns created with
etching according to the state of the art or the hollow spaces, respectively,
normally have a
diameter or depth, respectively, in the size range of .1 to 10 pm. The
invention, however,
envisions that the etching conditions are adjusted so that only small openings
or pores, re-
spectively, are created in the plastic surface which have a diameter and
especially a depth of
< .09 um, with < .05 p.m preferred. In this connection, depth means the extent
of the open-
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ings/gateways from the plastic surface into the plastic interior. Thus, no
etching in the classi-
cal sense takes place here as is the case with the known processes. The
invention envisions
that by creating small openings or pores, respectively, the plastic surface is
opened for the
diffusion of the metal ions of the metal salt solution. In other words, the
plastic surface is
transformed into something membrane-like, or a quasi diffusion membrane is
created in the
plastic surface, respectively. Mild etching conditions within the scope of the
invention also
mean that the etching conditions are applied with the intention that only the
mentioned small
pores are created in the plastic surface and that micro-caverns or interior
hollows, respec-
tively, in the plastic surface do not occur. In practical terms, diffusion
openings or diffusion
channels are created in the area of the plastic surface which have a depth of
< .09 wm, pref
erably < .OS pm.
The etching treatment envisioned by the invention can be realized with a
etching so-
lution and/or basically also by a plasma treatment or by plasma etching,
respectively.
Preferably, a etching solution used for etching contains at least one
oxidizer. Mild
etching within the scope of the invention also means that an oxidizer is used
in a low con-
centration. Permanganate and/or peroxodisulfate and/or periodate and/or
peroxide can be
used as oxidizers. In accordance with one type of process, etching is by an
acid etching solu-
tion which contains at least one oxidizer. Preferably, a aqueous etching
solution is used
which contains permanganate and phosphoric acid (H,PO,) and/or sulfuric acid.
In practical
20 terms, potassium permanganate is used as the permanganate. Very much
preferred is the use
of an acid etching solution which only contains phosphoric acid or principally
phosphoric
acid and only a little sulfuric acid. According to another type of application
of the invention,
etching treatment is by a basic aqueous solution, containing permanganate.
Here also potas-
sium permanganate is used by preference. In practical terms, the basic aqueous
solution con-
25 tams lye. The invention envisions that the type of etching solution used
depends on the type
of plastic to be treated. - The preferred concentration of the oxidizer in the
etching solution is
.OS to .6 molll. In practical terms, the etching solution contains .OS to .6
mol/1 permanganate
or persulfate. The invention also envisions that the etching solution contains
.l to .5 mol/1
periodate or hydrogen peroxide. As already stated above, permanganate is very
much pre-
30 ferred for the etching solution. The preferred permanganate proportion is 1
g/1 up to the solu-
bility limit of the permanganate, preferably potassium permanganate. In
practical terms, a
permanganate solution contains 2 to 1 S g/1 permanganate, preferably 2 to 15
g/1 potassium
permanganate. The invention envisions that the permanganate solution contain a
wetting
agent. - As already stated above, mild etching can also be achieved by the use
of a dilute
35 aqueous persulfate solution or periodite solution or a dilute aqueous
peroxide solution. Pref
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erably, the mild etching treatment with a etching solution is carried out
while agitating the
solution. - Subsequent to the mild etching, the plastic surface is rinsed, for
example 1 to 3
minutes in water. In accordance with a very much preferred type of application
of the inven-
tion, the treatment with the metal salt solution according to 1.2) is carned
out at a tempera-
s tore of maximally 30°C, preferably at a temperature between 15 and
25°C. Thus, it lies
within the scope of the invention to also carry out the treatment with the
metal salt solution
in the range of room temperature. In practice, the treatment with the metal
salt solution is
performed without agitation. The preferred treatment time is 30 seconds to 15
minutes, pref
erably 3 to 12 minutes. - Preferably, a metal salt solution is used which has
a pH value of
10 between 7.5 and 12.5, preferably adjusted to between 8 and 12. In
accordance with a pre-
ferred type of application of the invention, a metal salt solution is used
which contains am-
monia and/or at least one amine. The above-mentioned pH value adjustment can
be effected
with the help of ammonia, and in this case, within the scope of the invention,
an alkaline
metal salt solution is used. Basically, however, it is also within the scope
of the invention to
15 use a metal salt solution which contains one or more amines. For example,
the metal salt so-
lution may contain monoethanolamine and/or triethanolamine. Treatment with the
metal salt
solution, within the scope of the invention, means especially the immersion of
the plastic sur-
face into the metal salt solution.
According to a very much preferred type of application, which is especially
meaning-
20 ful within the scope of the invention, a cobalt salt solution is used as
the metal salt solution.
Preferably, the cobalt salt solution contains .1 to 15 g/1 Co(II) salt,
preferably 5 to 12 g/1
Co(II) salt. In practical terms the cobalt (II) solution contains cobalt (II)
sulfate and/or cobalt
(II) chloride. Preferably, the cobalt (II) solution contains .1 to 15 g/1
CoS04 ~ 7Hz0; very
much preferred is 1 to 10 g/1 CoS04 ~ 7H20. - According to a very much
preferred type of
25 application within the scope of the invention, a metal salt solution used
is especially a cobalt
salt solution, containing at least one oxidizer. The oxidizer may be hydrogen
peroxide, for
example. The oxidizer may also be made available by blowing air into the metal
salt solution.
If, in accordance with the preferred type of application of the invention, the
metal salt solu-
tion is a cobalt (II) salt solution, the oxidizer is preferred to be used with
the proviso that at
30 least part of the cobalt (II) is oxidized into cobalt (III). - Subsequent
to the treatment with the
metal salt solution, the plastic surface is as rinsed as required.
In accordance with the preferred type of application of the invention, the
plastic sur-
face is immersed into a aqueous alkaline solution between the process steps
1.2) and 1.3).
The treatment or immersion time is preferably 10 seconds to 3 minutes, .S to 2
min-
35 utes is very much preferred. Preferably, a bath temperature of maximally
30°C is used, 15 to
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25°C is preferred. For practical purposes, the aqueous alkaline
solution has a pH value of 9 to
14. The immersion in the aqueous alkaline solution is preferably in a dilute
sodium lye. The
scope of the invention includes the use of sodium hydroxide and/or potassium
hydroxide
and/or sodium carbonate for making the aqueous alkaline solution. It is very
much preferred
that the aqueous alkaline solution contain 5 to 50 g/1 sodium hydroxide or
potassium hy-
droxide. Preferred here is the concentration of sodium hydroxide or potassium
hydroxide to
be the higher, the higher the metal salt concentration of the metal salt
solution. In principle,
the plastic surface, instead of a aqueous alkaline solution, may also be
treated with a aqueous
acid dip solution. - It is within the scope of the invention to rinse with
water or distilled wa-
ter, respectively, subsequent to the immersion treatment.
In accordance with the preferred type of application of the invention, the
plastic sur-
face is treated with an alkaline solution of an alkali metal sulfide according
to process step
1.3). An ammonium sulfide may also be used. The sulfide, for example, may be a
monosul-
fide, disulfide, tetrasulfide or a polysulfide. According to the preferred
procedure an alkali
metal sulfide (MZS, M = alkali metal) is used, for practical purposes sodium
sulfide (NaZS}.
The concentration of the alkali metal monosulfide, preferably the sodium
sulfide, is preferred
to be .5 to 10 g/I; very much preferred is 2 to 8 g/1. For practical purposes,
the alkali solution
of the alkali metal sulfide contains S to 25 g/1 of sodium hydroxide, for
example 10 g/1 so-
dium hydroxide. The treatment with the sulfide solution preferably takes place
over a time
period of 15 seconds to 5 minutes; very much preferred is 30 seconds to 2
minutes. - The
treatment with the sulfide solution in accordance with process step 1.3) is
carried out pref
erably at a maximum temperature of 30°C; a temperature of between 1 S
and 25°C is pre-
ferred. - Subsequent to the treatment with the sulfide solution rinsing as
required takes place,
for example 1 to 3 minutes with cold water.
It is within the scope of the invention that the metal salt solution,
preferably a cobalt
salt solution and/or the sulfide solution, has added a complex builder for
stabilizing of the
affected solution. Thus, the metal salt solution may at least partially
contain the metal in the
form of a metal complex. It is further within the scope of the invention that
the metal salt
solution and/or the sulfide solution have a wetting agent added so that
improved wetting of
the plastic surface results.
Within the scope of the invention, a sulfide solution can be used which
contains at
least one substance from the group "Alcohol, dioI, polyol, ployalkanglycol,
ployalkenglycol,
gel/sol-building substance, such as silicic acid gel or aluminum oxide gel".
It is within the
scope of the invention to use mixtures of these substances in the sulfide
solution. - Within the
scope of the invention, a metal salt solution, preferably a cobalt salt
solution, may also be
used which contains at least one substance from the group "Alcohol, diol,
polyol, ployalkan-
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glycol, ployalkenglycol, gel/sol-building substance, such as silicic acid gel
or aluminum ox-
ide gel". It is within the scope of the invention to use mixtures of these
substances in the
metal salt solution.
According to the very much preferred type of application of the invention,
drying of
the plastic surface is carried out between process step 1.3) and process step
1.4). It is within
the scope of the invention that the drying is effected by a heat treatment of
the plastic surface
(with increased temperature), Preferably, the metallizing of the plastic
surface occurs only
subsequent to the drying. In principle, when applying the process in
accordance with the in-
vention, the treatment with the metal salt solution and/or the treatment with
the sulfide solu-
tion may be repeated. It is within the scope of the invention that in the case
of multiple
treatment with the sulfide solution, the plastic surface is dried subsequent
to any treatment.
After completion of procedure step 1.3), the direct metallization of the
plastic surface
may proceed. According to a very much preferred procedure which is especially
significant
within the scope of the invention, the plastic surface is nickel plated in a
nickel bath in ac-
cordance with procedure step 1.4). To this extent an electrolytic direct
metallization can be
carried out. Electro-chemical nickel plating preferably takes place in a Watts
electrolyte. In
practice, the treatment time is 10 to I S minutes in this connection, and the
electrolyte tem-
perature is preferred to be 30 to 40°C. It is within the scope of the
invention that for electro-
chemical nickel plating an initial current density of .3 A/dm2 is used which
later is increased
to 3 A/dmz. In this manner a nickel layer can be deposited on the plastic
surface by electro-
lytic metallizing.
First, the invention is based on the knowledge that the plastic surface when
etched as
described in the invention is manipulated in such a manner that ultimately,
surprisingly, a
very tight adherence of the applied metal layer to the plastic surface is
achieved. These
tightly adhering metal layers show a high temperature cycling resistance and,
accordingly,
survive all the customary temperature cycling shocks. Further, the invention
is based on the
knowledge that using the process described in the invention conditions can be
created within
a relatively short time which are optimally suited for the subsequent
application of the metal
or the nickel layer, respectively. Although it is basic to the scope of the
invention that the
process steps are repeated and especially to repeat steps 1.2) and 1.3),
surprisingly, optimal
results are also achievable without the repetition of these process steps.
Within the scope of
the invention, with little investment and little material consumption, high-
quality metal lay-
ers, especially nickel layers, are obtained on plastic surfaces. Neither does
it require complex
equipment, and traditional or commonly available fixtures can be used. In
order to apply the
process which is the subject of the invention, it is of advantage that only
limited space is re-
quired. In addition, the time involved in applying the process which is the
subject of this in-
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vention is short, so that also a substantial time savings results when
compared with the
known processes. Further, the process can be controlled in a functionally
secure and simple
manner which ultimately affects the quality of the metal layers. It is of
special significance
within the scope of the invention that by the application of the measures
contained in the in-
s vention, a surprising variety of plastics can be metallized effectively and
in a functionally
secure manner. This is especially surprising in view of the fact that only a
certain few plastics
could be satisfactorily metallized with the processes known heretofore. First,
pure ABS can
be metallized optimally and without problems using the process which is the
subject of the
invention. This also applies to ABS/PC blends and especially also to ABS/PC
blends with a
relatively high PC component (PC = Polycarbonate). Pure PC can also be
metallized without
problems with the help of the process which is the subject of the invention.
Such an effective
and functionally secure metallization, surprisingly, is also possible with
many other plastics,
among others especially also in the case of the following plastics: POM
(polyoxymethylene),
PEEK (polyetheretherketone), PP (polypropylene). In view of the fact that, in
accordance
with the invention, etching of the plastic surface at high temperatures is not
necessary, en-
ergy savings may also be achieved. Since only mild etching conditions are
required, the most
varied etching solutions can be used in different ways so that the process
which is the subject
of the invention is not subject to restrictions from this point of view
either. Based on the mild
etching solutions to be adjusted in accordance with the invention, it is of
advantage to dis-
pense with aggressive etching solution components, for example chromic acid. -
Due to the
fact that preferably the process steps 1.1), 1.2) and 1.3) are carried out at
a maximum tem-
perature of 30°C, preferably at a temperature of 15 to 25°C, the
process which is the subject
of the invention only requires mild conditions over-all which, among others,
results in a con-
siderable energy savings. In addition, due to the mild conditions, undesirable
side reactions
are avoided to a large extent. With the process which is the subject of the
invention, a very
selective metallization of the plastic surface can be achieved. It should be
emphasized that
with this procedure the use of racks can be avoided in a functionally secure
manner.
In the following, the process is explained on the basis of an example:
Depending on
the plastic type to be metallized, either an acid or an alkaline etching
solution is employed. In
accordance with a preferred type of application of the invention, an acid
etching solution is
used for mild etching, consisting of 100 to 300 ml/1 water, 700 to 900 ml/1
concentrated
phosphoric acid and 3 to 7 g/1 potassium permanganate. According to an
application exam-
ple, the acid etching solution consists of 74% by weight of phosphoric acid,
26% by weight
of water and 5 g potassium permanganate. According to another type of
application of the
invention, an alkaline etching solution is used for mild etching which, in
practice contains 20
to 40 g/1 sodium hydroxide and 5 to 15 g/1 potassium permanganate. In
accordance with an
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application example, the aqueous alkaline etching solution consists of 30 g/1
sodium hy-
droxide and 10 g/1 potassium permanganate. With the acid etching solution or
the alkaline
etching solution explained above, etching takes place preferably at room
temperature over a
period of 10 minutes. Subsequent to the etching treatment, the plastic surface
is rinsed as re-
quired. - Furthermore, in accordance with the preferred type of application of
the invention,
an ammoniacal metal salt solution is employed which contains .l to 12 g/1
cobalt (II) sulfate,
as well as 10 to 50 ml/125% ammonia solution. Activation with the cobalt salt
solution pref
erably occurs at room temperature i.e. during a treatment time of 5 to 10
minutes. Subsequent
to the activation with the cobalt salt solution, the plastic surface is rinsed
with water as re-
quired. - For the aqueous alkaline solution into which the part preferably is
immersed subse-
quent to the treatment with the metal salt solution, 10 to 50 g11 sodium
hydroxide is dissolved
in water. In accordance with an application example, a aqueous alkaline
solution with 20 g/1
sodium hydroxide is employed. Immersion in the aqueous alkaline solution, in
practice, takes
place at room temperature and over a treatment time period of .5 to 2 minutes.
- Preferably, a
sulfide solution is used as the alkaline sulfide solution which contains .S to
10 g/1 sodium
sulfide (NaZS), as well as S to 26 g/1 sodium hydroxide. According to a
preferred application
example, an alkaline alkali sulfide solution is employed which contains 5 g/1
sodium sulfide
(Na2S), as well as 10 g/1 sodium hydroxide. Preferably, the sulfide treatment
is carried out at
room temperature and over a treatment period of .5 to 5 minutes. Subsequent to
the sulfide
treatment, the plastic surface is rinsed with water as required. It is within
the scope of the
invention that prior to the metallization, especially nickel plating, the
plastic surface is dried.
The invention is explained in more detail in the following by means of six
examples.
The application examples 1 and 2 correspond to the state of the art
(comparison examples),
while examples 3 to 6 clarify the process which is the subject of the
invention. In the appIi-
cation examples 1, 3 and 5 ABS plastic discs with a surface of 50 cmz were
used, while die-
pressed products of impact-resistant polystyrol with a surface of 70 cm2 were
used for exam-
ples 2, 4 and 6. In the following, the notation "M" corresponds to the
concentration "mol/1".
Application Example _1
Disks of ABS plastic having a surface of 50 cm2 were pickled for 3 minutes at
70°C
in a etching solution consisting of 4 M HZS04 and 3.5 M Cr03. Subsequently,
there was a
rinse with water. Following this, the plastic articles were treated for 30
seconds in an ammo-
niacal solution with .5 M CuS04 ~ 5 H20 having a pH value of 9.5 and a
temperature of
20°C. The plastic articles then were submerged for 20 seconds in
distilled water and, subse-
quently, for 30 seconds treated with a sulfide solution, containing .1 M Na2S2
and having a
temperature of 20°C. After this treatment, the plastic articles were
again washed in cold wa-
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ter. Following this was electro-chemical nickel plating. For this, the
articles were treated for
15 minutes in a Watts electrolyte, containing 1.2 M NiS04 ~ 7 H20, .2 M NiClz
~ 6 H20 and
M H,B03. The initial current was .3 A/dm2, and the nickel plating was earned
out at 40°C.
Application Example 2
5 Die-pressed articles of impact-resistant polystyrol having a surface of 70
cm2 were
pickled for 30 seconds in a etching solution, containing 15 M HZS04 and .1 M
CrO, and
having a temperature of 20°C. Subsequently, the articles were washed in
water and following
that were immersed for 30 seconds in an emulsion of .2 g/1 Xylol and .2 g/1
Sintanol at 20°C.
After the etching treatment, the articles were washed with distilled water.
The articles then
were treated for 30 seconds with a metal salt solution, containing .5 M CuS04
~ 5 HZO
Monoethanolamin having the pH value adjusted to 9.8, and the temperature of
the solution
was 20°C. Subsequently, the articles were immersed in distilled water
for 20 seconds and
following this treated with a sulfide solution for 30 seconds which contained
.1 M NaS and
had a temperature of 20°C. Subsequently, the treatment with the metal
salt solution and the
following treatment with the sulfide solution as described above was repeated.
After this
treatment the articles were rinsed in distilled water and electro-chemically
nickel plated in a
Watts electrolyte as described in Application Example 1.
Application Example 3
The surface of the ABS plastic parts was pickled at room temperature with a
solution
of 15 M HZS04 and .OS M KMn04 . After the etching, the articles were rinsed
with water and
subsequently treated in an amoniacal solution for 10 minutes which contained
.1 M CoS04
and had a pH value of 10 as well as a temperature of 20°C. Following
this, the articles were
treated with water which had been acidified with HZS04 to a pH value of 1.
Subsequently, for
a period of 30 seconds, there was a treatment with a sulfide solution
containing .O1 M Na2S2.
After this treatment, the articles were rinsed with distilled water and then
electro-chemically
nickel plated with a Watts electrolyte in accordance with Application Example
1.
Agptieation Exam~te 4
The surface of the articles of impact-resistant polystyrol was pickled for a
period of
10 minutes and at room temperature with a solution containing 17 M HZS04 and 1
M HZO2.
After etching, the articles were rinsed with water and subsequently treated
for 10 minutes
with a solution containing .O1 M CoF3 and monoethanolamine up to a pH value of
8 and at a
temperature of 20°C. The articles then were immersed for 20 seconds in
a aqueous alkaline
solution which contained sufficient sodium hydroxide that it had a pH value of
14. Subse-
quently, they were treated for 30 seconds with a sulfide solution containing
.05 M KZS4. The
CA 02350422 2001-05-11
WO 00/29646 PCT/US99/26066
-11-
treated articles then were rinsed with distilled water, dried and then nickel
plated for 15 min-
utes in a Watts electrolyte in accordance with Application Example 1.
Application Example 5
The surfaces of the ABS plastic articles were pickled at room temperature with
a so-
lution which contained 13 M H3P04 and .S KZSZO9. After etching, the articles
were rinsed
with water. Subsequently, they were treated for 10 minutes in a solution
containing .25 M
CoS04 and triethanolamine up to a pH value of 9 at 20°C. Thereafter,
the articles were im-
mersed in a aqueous alkaline solution which had been set to a pH value of 9
with sodium
carbonate. Subsequently, they were treated for 30 seconds in a sulfide
solution, containing
.02 KZS,. After the treatment, the plastic articles were rinsed with distilled
water, dried and
subsequently, over a time period of 1 S minutes, electro-chemically nickel
plated, using a
Watts electrolyte in accordance with Application Example 1.
Application Example 6
The surface of the articles of impact-resistant polystyrol was pickled at room
tem-
perature with a solution which contained 17 M H2S0, and .5 M KI04. After
etching, the arti-
cles were rinsed with water and subsequently were treated with a solution,
containing .O1 M
CoF3 which had been adjusted to a pH value of 12 with ammonia and which had a
tempera-
ture of 20°C. The articles then were immersed for 20 seconds in an
acidic solution which had
been adjusted to a pH value of S with the help of acetic acid. Subsequently,
the articles were
treated for 30 seconds in a sulfide solution which contained .O1 M NaZS. After
this treatment,
the articles were rinsed with distilled water, dried and subsequently electro-
chemically nickel
plated for 15 minutes, using a Watts electrolyte in accordance with
Application Example 1.
T'he data relating to the processes carried out in accordance with the
Application Ex-
amples 1 to 6, as well as the properties of the resulting metal layers are
summarized in the
following table.
CA 02350422 2001-05-11
WO 00129646 PCT/US99/26066
12
,
O
x
~ + Y
a.~ 0 0 ~ o vN
0
N
x
+o
Y N
p V1 O ~ N
v7 ~ x + V N Cv ~ ~ ~-~ + N N +
O
x
+
y Ci Y N
'~ O ~ ~ .r tn
a. ~ rr~ x r. ~ a
~t~W .U. mx+ V ~ oor~r~ ~-~ + ~ W +
O
N
x ..
+o
N
x+ v ~ °z~ ~ + ~ ~+
p
~~_
v~ ~ a
0o e~ ~ a~
N.~'~' ~U V ~, ~;z~ N , M ~ ,
0
N
x
O N
x v ~ ~z~ ~ , o , ,
a~ ~ a ~, ~ co a
U ~~
~ a~ ~ ~ v
~ ' .r~ ,~.~.
b . O U .~ i.~ '~," ~" U ~0
.O t3. U ~ .~'..'' cd ~ ~ ~ G
O ~ U C/~ C"r b N _.'3 .~ .rte .~ ~ V
U ~ O O U ~ ~ O ~.,' 4r ~ ~.." ~ ~ U tH, ~ N
(..," . .--~ V7 U T'.. ~, 4r ~ O O .~4' .~C ~ O
b0 tn .O N UV O~~ b4vUGU~~~ .U
~.,'~~~,
v a ~ ~ ~ 4.~ ~.~ a >~ p ~'~,~r y v ,
~ P.r W ~ ~ ~ x ~i ~ z ~ w U ..o + w > a W w .+,. ~
