Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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One-step pretreatment method of metallic substrates at non-neutral pH values
for metal cold forming
The present invention relates to a method of pretreatment of a metallic
substrate for
a subsequent metal cold forming process, said method comprising at least steps
(1)
and (2), namely providing at least one substrate having at least one surface
at least
partially made of at least one metal (step (1)), contacting the at least one
surface of
the substrate provided in step (1) with an aqueous lubricant composition (B)
(step
(2)), wherein the aqueous lubricant composition (B) comprises besides water at
least
constituents (b1) to (b4) and optionally (b5), namely as (b1) at least one
homopolymer and/or copolymer being prepared by polymerization of at least
vinyl
pyrrolidone as at least one monomer, wherein (b1) has a polydispersity index
(PDI) in
a range of from 1.5 to 8.0, as (b2) at least one wax, as (b3) at least one
defoamer,
and as (b4) (i) oxalate anions and/or phosphate anions or (ii) calcium
cations,
chloride anions and hydroxide anions, as well as optionally Fe(III) ions as
(b5),
wherein (b5) is present in case at least oxalate anions are present as (b4), a
pretreated metallic substrate obtainable by the inventive method, a method of
cold
forming of a metallic substrate, and an aqueous lubricant composition (B) as
defined
above.
Background of the invention
Cold forming of metallic workpieces is conventionally achieved by rolling such
as
thread rolling, drawing, in particular sliding drawing or deep-drawing,
pressing,
stretch forming and/or cold upsetting of the workpieces in order to transform
them
into articles having a desired shape. Cold forming usually takes place at
temperatures below the recrystallization temperature of the metallic material
of the
workpiece subjected to cold forming, such as at temperatures below and up to
450 C. No external heating source is used in the method of cold forming.
Instead,
any heat development or temperature increase in general is caused solely by
frictional forces between the metallic workpiece and the work tools used
during
forming and due to internal friction forces generated by material flow in the
workpiece. Cold forming usually results in an increased pressure, e.g. for
steel, for
example in the range of from 200 MPa to 1 GPa and sometimes even up to 2 GPa.
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The temperature of the workpieces to be cold formed is initially at ambient
temperature, i.e., at approximately 10 to 32 C. In case the workpieces are
pre-
heated prior to forming, for example to a temperature in the range from 650 to
1250 C, the forming process is no longer a "cold forming" process, but rather
a
"semi-hot" forming, a hot forming or a forging process.
If the metallic workpieces are cold formed to shaped articles with a
comparably only
low degree of deformation rather low forces for the cold forming process to
take
place are needed. For this purpose, conventionally non-reactive forming oils
are
applied to the workpieces. At higher degrees of deformation, however, usually
first a
conversion coating layer is applied onto the surfaces of the workpieces and
then a
further lubricant layer is applied on top prior to the cold forming process in
order to
prevent a cold welding during the cold forming. Such two-steps-processes are
e.g.
disclosed in EP 0 232 929 Al, WO 94/16119 Al, WO 2009/095373 Al, WO
2009/095375 Al, WO 2009/095374 Al and JP S56 72090 A.
EP 0 232 929 Al relates to a two-step pretreatment method for facilitating a
subsequent cold forming of stainless steel substrates. In a first step an
oxalate
coating is applied onto the substrate by making use of a solution containing
inter alia
oxalic acid as well as a water-soluble polymer. Afterwards, in a second step a
lubricant is applied onto the oxalate coating. Metal soaps are named as
suitable
lubricants in EP 0 232 929 Al. WO 94/16119 Al discloses a liquid aqueous
composition for forming a conversion coating on metal surfaces in a first step
for a
subsequent cold forming process. The composition comprises an organic cationic
polymer and may further comprise oxalate anions. In a second step a
lubricating film
can be applied onto the conversion film by making use of inter alia oil-based
lubricants and/or soaps. WO 2009/095373 Al discloses a two-step pretreatment
method for facilitating a subsequent cold forming of metal substrates. In a
first step a
phosphate layer on the surface of the workpiece is formed by using an aqueous
acidic phosphatizing solution containing Ca, Mg and/or K cations. In a second
step,
an aqueous alkaline lubricant composition containing organic polymers is
applied.
WO 2009/095375 Al and WO 2009/095374 Al both disclose a method for the
preparation of metallic workpieces for cold forming. A lubricant coating layer
is
applied onto the metallic surface of the workpieces optionally bearing a
conversion
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coating layer as separating layer by contacting the surface with an aqueous
lubricant
composition comprising at least one water-soluble, water-containing or water-
binding
oxide and/or silicate and an organic polymer in case of WO 2009/095375 Al or
by
contacting the surface with an aqueous lubricant composition comprising at
least two
waxes and an organic polymer in case of WO 2009/095374 Al. Finally, JP S56
72090 A relates to a two-step pretreatment method for facilitating a
subsequent cold
forming of steel substrates. An oxalate coating is applied for this purpose
onto the
substrates in a first step. The oxalate coating is obtained by making use of a
solution
containing inter alia oxalic acid and a water-soluble organic titanium
compound as
well as a polyvinyl pyrrolidone. In a second step, a lubricant is applied onto
the
oxalate coating. Metal soaps and solid lubricants are named as suitable
lubricants in
JP S56 72090 A.
There are, however, several drawbacks as far as these processes known in the
prior
art are concerned. First of all, both for ecologic reasons and in order to
avoid the
formation of undesired phosphorous-induced delta ferrite on the substrate, it
is
desired to not use phosphate coating films as conversion coating films such as
the
conversion coating films applied in the process disclosed in WO 2009/095373
Al, but
to rather only use phosphate-free systems. As far as the lubricant
compositions
zo known from the prior art are concerned, oil-based lubricant
compositions in general
lead to a higher VOC-content, since considerable amounts of oil can evaporate
during their use. In addition, oil-based lubricant systems may cause safety
issues, as
they are flammable and must be stored at flash points >150 C as hazardous
materials. For these reasons, the use of oil-based lubricant formulations is
undesired.
Solid lubricants such as lubricants based on MoS2 and/or graphite are only
feasible
for heavy cold forming with extensive degrees of deformation and thus, such
lubricants are of limited use only. Furthermore, sulfide present in such
lubricant films
often has a detrimental effect in particular on stainless steel. The use of
aqueous
lubricant compositions is thus more desirable both for ecologic and economic
reasons than using solid and/or oil-based lubricants.
Conventional aqueous lubricant compositions of the prior art are, however,
usually
alkaline compositions such as the (metal) soaps and soap solutions disclosed
in EP
0 232 929 Al, WO 2009/095373 Al, WO 2009/095375 Al, WO 2009/095374 Al and
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JP S56 72090 A, which are for example based on alkali or earth alkali
stearate.
These are only stable under alkaline conditions and are, e.g., not stable in
an acidic
medium. Further, the alkaline lubricant compositions of the prior art often
have only
comparably short lifetimes and thus have to be renewed rather frequently.
This, of
course, is disadvantageous both from an ecological view (higher amounts of
water
and of the constituents present in the compositions have to be used) and an
economic view (higher energy costs and changeover time). In contrast to these
aqueous alkaline lubricant compositions used for providing a lubricant layer
on the
prior to be applied conversion coating layer, the compositions used for
generating
said aforementioned conversion coating layer are acidic compositions as
already
mentioned hereinbefore. For performing such a two-steps pretreatment process
usually two different open treatment baths are employed, into which the
metallic
workpieces are dipped, namely a first bath containing the aqueous acidic
conversion
coating composition and a second bath containing the aqueous alkaline
lubricant
composition. It is essential, however, to include a rinsing and/or
neutralization step
between these two dipping steps in order to remove any excessive acid present
onto
the workpiece after having it removed from the first acidic bath and before
having
dipped it into the second alkaline bath in order to preserve the life of the
two baths
and in particular of the second bath as long as possible. It is, however,
disadvantageous for economic and ecological reasons to have to necessarily
carry
out such a rinsing and/or neutralization step. Simple mixing or combining the
conventional aqueous acidic compositions such as phosphate and/or oxalate
compositions for providing the conversion coating layer with the conventional
aqueous alkaline compositions for providing the lubricant layer is not
possible as
zs these compositions are not miscible with each other and consequently
an undesired
phase separation would be observed. Moreover, most of the known organic
polymer
dispersions used for preparing conventional aqueous alkaline lubricant
compositions
are unstable in an acidic environment. Therefore, it is not always possible to
simply
use acidic versions of the known aqueous alkaline lubricant compositions.
EP 3 290 544 Al relates to an acidic water-based lubricating coating agent
having a
pH value of 2.0 to 6.5, which inter alia contains a chemical conversion
component
such as oxalic acid and a lubricating component such as a lipophilic
lubricating
component including an oil or a soap. The coating agent may further comprise a
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water-based resin as a binder component. EP 3 290 544 Al further discloses a
one-
step pretreatment method of metal substrates for a subsequent cold forming.
JP S54 5847 A relates to a lubricant composition for facilitating the cold
forming of
5 metals. The lubricant contains oxalic acid and at least one constituent
selected from
water-soluble organic titanium compounds, vinyl pyrrolidone homopolymers and
vinyl
pyrrolidone copolymers. The lubricant composition may further contain a
lubricating
aid.
WO 2020/165035 Al discloses a one-step pretreatment method for preparation of
steel and/or steel alloy workpieces for cold forming. An oxalate and lubricant
layer on
a metallic surface is formed by using an aqueous acidic oxalating solution
containing
a film-forming polymer. A wide range of polymers may be used for preparing the
solution. However, this lubricant is not necessarily stable in other acidic
solutions
such as phosphating solutions and is also generally not stable in alkaline
solutions. In
addition, it may contain a lubricating oil. The use of such oils is, however,
in general
disadvantageous for the reasons outlined hereinbefore.
In addition, the conventional pretreatment processes for cold forming known in
the
prior art not always result in a sufficiently high coating weight of the
lubricant layer
formed on the workpiece or - if a separating layer such as a conversion
coating layer
is also present underneath the lubricant layer - in a sufficiently high
coating weight of
the lubricant layer and said separating layer combined. This may result in
only
insufficient adhesion properties of the layer(s) to the metallic substrate.
Further, this
can result in an ineffective separation of the tool from the workpiece after
and during
cold forming and in an only ineffective reduction of the coefficient of
friction or even in
an undesired cold welding, as an only insufficiently high amount of the
coating
layer(s) as measured by their coating weight remains present on the workpieces
during the cold forming process.
Thus, there is a need for simplifying the conventional surface pretreatment
processes
for metal cold forming that make use of aqueous lubricant compositions both
for
economic reasons and for ecological reasons, in particular to provide an
improved
technology for the water-based pretreatment of metallic substrates for the
cold
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forming process that requires fewer treatment steps and makes use of aqueous
lubricant compositions, which contain suitable constituents that are stable
both in an
acidic and in an alkaline medium. At the same time such a simplified
pretreatment
must still lead to sufficiently high coating weights of the coating layer(s)
formed on
the metallic substrates in order to both ensure a good adhesion to the
substrate and
an effective reduction of the coefficient of friction during cold forming and
to prevent
cold welding.
Problem
It has been therefore an object underlying the present invention to provide a
simplified surface pretreatment method for metal cold forming that makes use
of an
aqueous lubricant composition both for economic reasons and for ecological
reasons, in particular to provide an improved technology for the water-based
pretreatment of metallic substrates for the cold forming process that requires
fewer
treatment steps and makes use of aqueous acidic lubricant compositions, which
are
stable both in an acidic and in an alkaline medium. At the same time, however,
it is
required that such a simplified pretreatment must still lead to sufficiently
high coating
weights of the coating layer(s) formed on the metallic substrates in order to
both
ensure a good adhesion to the substrate and an effective reduction of the
coefficient
of friction during cold forming and to prevent any cold welding.
Solution
zs This object has been solved by the subject-matter of the claims of the
present
application as well as by the preferred embodiments thereof disclosed in this
specification, i.e., by the subject matter described herein.
A first subject-matter of the present invention is a method of pretreatment of
a
metallic substrate for a subsequent metal cold forming process, said method
comprising at least steps (1) and (2) and optionally step (3), namely
(1) providing at least one substrate having at least one surface at
least partially
made of at least one metal and/or alloy thereof, wherein said metal and/or
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alloy thereof is at least one of steel, aluminum and alloys of aluminum and/or
steel,
(2) contacting the at least one surface of the substrate provided
in step (1) with an
aqueous lubricant composition (B) having a pH value, which is in the non-
neutral pH range, wherein the neutral pH range is a pH range of from >6.0 to
<8.0,
wherein the aqueous lubricant composition (B) comprises besides water at
1.0 least constituents (Li) to (b4) and optionally (b5), which are
different from one
another, namely
(b1) at least one film-forming polymer, which is a homopolymer and/or
copolymer being prepared by polymerization of at least vinyl pyrrolidone
as at least one monomer, wherein said homopolymer and/or copolymer
has a polydispersity index (PDI) in a range of from 1.5 to 8.0,
(b2) at least one wax,
(b3) at least one defoamer, and
(b4) (i) oxalate anions and/or phosphate anions or (ii) calcium cations,
chloride anions and hydroxide anions, as well as
(b5) optionally Fe(III) ions, wherein constituent (b5) is present in case at
least oxalate anions are present as constituent (b4),
and
(3) optionally drying the coating film obtained after having performed step
(2).
A further subject-matter of the present invention is a pretreated metallic
substrate
obtainable by the inventive method.
A further subject-matter of the present invention is a method of cold forming
a
metallic substrate, characterized in that it comprises a step of subjecting
the inventive
pretreated metallic substrate to a cold forming process.
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A further subject-matter of the present invention is an aqueous lubricant
composition
(B) as defined hereinbefore in connection with the inventive pretreatment
method.
A further subject-matter of the present invention is a master batch to produce
the
inventive aqueous composition (B) by diluting the master batch with water and
if
applicable by adjusting the pH value.
It has been surprisingly found that aqueous lubricant composition (B), in
particular its
constituents (b1) and (b2), is compatible to organic and/or inorganic acids,
in
particular to oxalic acid and phosphoric acid, and thus represents an acid
stable
composition. At the same time, it has been unexpectedly found that aqueous
lubricant composition (B), in particular its constituents (b1) and (b2), is
also
compatible to organic and/or inorganic bases, and thus represents also a
composition, which is stable in alkaline medium. Thus, advantageously
basically the
same composition can be used both as acidic aqueous lubricant composition and
as
alkaline aqueous lubricant composition depending on the mere selection of
constituent (b4). This offers a greater flexibility to the end user.
It has been in particular surprisingly found that it is thus possible to
include (i) oxalate
and/or phosphate anions into composition (B) as (b4), in particular when the
pH
value of composition (B) is in the non-neutral acidic range up to pH 6.0, or
to include
(ii) calcium cations, chloride anions and hydroxide anions into composition
(B) as
(b4), in particular when the pH value of composition (B) is in the non-neutral
alkaline
range of 8.0 or higher. This has the advantage that composition (B) can be
used in
the inventive method both as an aqueous acidic or alkaline composition in a
single
step. In particular, aqueous acidic or alkaline composition (B) can be used
both as an
lubricant composition and as a conversion coating composition in a single step
only
and, consequently, it is not necessary to apply any conversion coating in an
additional step prior to applying the lubricant, which, of course, has both
economic
and ecologic advantages. Similarly, it is not necessary to apply any
lubricating aids
subsequently.
In particular, it has been surprisingly found that all constituents present in
aqueous
lubricant composition (B) can be formulated as and into an acidic composition
at a
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pH value in the range of from 0.1 to 6.0 or into an alkaline composition at a
pH value
in the range of from 8.0 to 14Ø It has been in particular surprisingly found
that
composition (B) is stable both under such acidic conditions and under such
alkaline
conditions and that in particular the at least one film-forming polymer (b1)
as well as
the at least one wax (b2) present in composition (B) are stable in both of
these
environments in the additional presence of (i) oxalate and/or phosphate anions
(b4)
in case of acidic conditions or in the additional presence of (ii) calcium
cations,
chloride anions and hydroxide anions (b4) in case of alkaline conditions, even
when
these ions are present in comparably high concentrations in composition (B).
As
mentioned above, this offers a greater flexibility to the end user.
It has been further surprisingly found that - as composition (B) can be used
in the
inventive method both as lubricant composition and as a conversion coating
composition in a single step only - no rinsing and/or neutralization steps
have to be
performed at all in contrast to conventional multi-step methods, wherein such
a
rinsing and/or neutralization step has to be performed at least after applying
the
conversion coating composition and before applying the lubricant composition.
In addition, it has been further found that the coating film obtained after
step (2) is a
zo combined conversion and lubricant film. Thus, the coating film obtained
combines the
properties of a conversion layer and a lubricant layer. The lubricant coating
film can
be present on top of the conversion coating film. The combined layers can be
separated and adjusted in part. When a substrate having a surface at least
partially
made of aluminum and/or an alloy thereof is used, it has been found that when
using
a composition (B) comprising calcium cations, chloride anions and hydroxide
anions
as constituent (b4), a calcium aluminate coating film is formed as conversion
coating
film as aluminate anions are formed in situ after application of composition
(B) onto
the surface.
In addition, it has been surprisingly found that the coating layer obtained
from
applying composition (B) adheres firmly on the substrate and shows good
lubricant
properties. Thus, the substrate pretreated by the inventive method can be
subsequently subjected to a metal cold forming process including cold
extrusion and
wire drawing with high speed drawing. In the cold forming of substrates, it
has been
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found that a coating layer obtained from application of composition (B) to the
substrate can be efficiently subjected to a drawing step for the purpose of
metal cold
forming. In the cold forming of substrates such as steel wire in a wire-
drawing
machine, it has been found that a lubricant layer obtained from application of
5 composition (B) to the substrate can be efficiently used even with a
drawing up to
35% cross-area, decreasing in each drawing step.
Furthermore, it has been surprisingly found that the coated metallic
substrates
obtained by the inventive method bear a sufficiently high coating weight of
the
10 coating layer(s) formed on the metallic substrates obtained from applying
composition (B). The resulting coating layer(s) is/are homogenous, thick and
adhered
firmly on the surface of the substrate. It has been found that such a high
coating
weight not only ensures a good adhesion to the substrate, but also an
effective
reduction of the coefficient of friction during cold forming and to prevent
any cold
welding. It has been surprisingly found that higher coating weights are
obtained when
performing the inventive method comprising one contacting step (step (2)) only
compared to performing conventional multi-step methods, wherein conversion
coating and lubricant layers are applied in separate steps. In case oxalate
anions are
present as (b4) it has been surprisingly found that the additional use of
Fe(III) ions as
accelerator positively influences the coating weight compared to the use of
n itroguan id me.
Moreover, it has been found that coated metal workpieces obtained from the
inventive method have a good corrosion resistance. It has been surprisingly
found in
zs this regard that the presence of the optional corrosion inhibitor (b6)
in composition
(B) does not negatively influence the formation of an oxalate and/or phosphate
and/or aluminate conversion coating layer in any manner when performing the
inventive method as the conversion coating layer formed has an excellent
coating
quality, in particular when a mixture of an alkyl amide and an alkanolamine is
used as
optional constituent (b6). Further, it has been found that no stable foams
have been
formed during the inventive surface treatment process.
In addition, it has been surprisingly found that the lubricant properties of
the lubricant
film obtained after step (2) or after optional step (3) of the inventive
method are in
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particular improved compared to making use of conventional lubricant
compositions
due to the use of the specific film-forming polymer (b1) in combination with
the at
least one wax (b2).
It has been further surprisingly found that baths containing the acidic
aqueous
lubricant composition (B) have comparably long lifetimes, in particular longer
lifetimes
that bath containing conventional alkaline aqueous lubricant compositions.
This, of
course, has economic and ecologic advantages.
Detailed description of the invention
The term "comprising" in the sense of the present invention, in particular in
connection with the inventive method, the inventive composition (B) and the
master
batch used to prepare the composition (B), preferably has the meaning
"consisting
of". In this case, for example, with regard to the inventive composition (B),
in addition
to the mandatory constituents therein (constituents (b1) to (b4), optionally
(b5), and
water) one or more of the further optional components mentioned hereinafter
may be
contained in the composition. The same principle applies with respect to the
composition (B) used in the inventive method and the master batch. All
zo components/constituents can be present in each case in their preferred
embodiments
mentioned hereinafter. The same applies to the further subject-matters of the
present
invention.
The proportions and amounts in wt.-% (% by weight) of any of the constituents
given
hereinafter, which are present in each of the compositions such as composition
(B)
add up to 100 wt.-%, based in each case on the total weight of the respective
composition such as composition (B).
Inventive pretreatment method
The inventive method is a method of pretreatment of a metallic substrate for a
subsequent metal cold forming process. The inventive method comprises at least
steps (1) and (2) and optionally additionally step (3). The inventive method
may
comprise one or more further additional optional steps.
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Preferably, the inventive method does not comprise any oxalating and/or
phosphatizing steps besides step (2), and, further, does not comprise any
lubricating
steps besides step (2).
Step (1)
In step (1) of the inventive method at least one substrate having at least one
surface
at least partially made of at least one metal and/or alloy thereof is
provided. Said
metal and/or alloy thereof is at least one of steel, aluminum and alloys of
aluminum
and/or steel.
The surface of the substrate used is at least partially made of at least one
metal
and/or alloy thereof, i.e., at least one region of said surface is made of at
least one
metal and/or alloy thereof. The surface can consist of different regions
comprising
different metals. Preferably, the overall surface of the substrate is made of
at least
one metal and/or alloy thereof. More preferably, the substrate consists of at
least one
metal and/or alloy thereof.
Preferably, the at least one metal is selected from the group consisting of
aluminum,
aluminum alloys, zinc, steel including cold rolled steel, hot rolled steel,
galvanized
steel (zinc plated steel) including hot-dip galvanized steel (hot zinc dipped
steel) or
electrolytically galvanized steel, steel alloys, aluminum and/or aluminum
alloys.
Preferably, the at least one surface of the substrate is made of steel,
aluminum
and/or of a steel and/or aluminum alloy, more preferably the substrate as such
is
made of steel, aluminum and/or of a steel and/or aluminum alloy.
As substrates, e.g., strips, sheets, slugs, wires, wire coils, more
complicated shaped
parts, sleeves, profiles such as hollow or solid profiles, tubes, discs,
discs, rods, bars
or cylinders can be used.
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Optional steps (la) and (lb) and (lc)
The surfaces to be substrates provided in step (1) may be cleaned by means of
an
acidic, alkaline or pH-neutral cleaning composition and/or etched before
treatment
with the composition (B) in step (2) as it will be outlined hereinafter: Prior
to step (2)
of the inventive method one or more of the following optional steps can be
performed, preferably in this order:
Step (la): cleaning, preferably by making use of an alkaline aqueous
cleaning
composition for surfaces made at least partially of steel and/or an alloy
thereof and/or by making use of a pH-neutral aqueous cleaning
composition for surfaces made at least partially of aluminum and/or an
alloy thereof, and optionally subsequently rinsing the surface of the
substrate provided in step (1), and/or
Step (1 b): subjecting the surface of the substrate to acidic pickling,
Le., etching,
and subsequently rinsing the surface of the substrate, and/or
Step (1c): optionally activating the surface of the substrate by
using an aqueous
activating composition (A) being different from composition (B).
zo Alternatively, optional steps (1a) and (1 b) may be performed in one
step. Preferably,
both steps (1a) and (1 b) are performed. Rinsing included in step (1a) is
preferably
performed with deionized water or tap water. Preferably, the acidic pickling
is
performed by making use of hydrochloric acid, hydrofluoric acid, sulfuric
acid, nitric
acid and/or phosphoric acid. In the case phosphate anions are present as
constituent
(b4) in composition (B), the surface of the substrate can optionally be
activated by
using an aqueous activating composition (A) according to optional step (1c),
e.g., by
using commercially available activating product Gardolenee V 6522 from
Chemetall
GmbH.
Step (2)
In step (2) of the inventive method the at least one surface of the substrate
provided
in step (1) is contacted with, preferably dipped into, an aqueous lubricant
composition
(B).
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The treatment procedure according to step (2), i.e., the "contacting", can,
for
example, include a spray coating and/or a dip coating procedure. The
composition
(B) can also be applied by flooding the surface or by roll coating or even
manually by
wiping or brushing. However, dipping is preferred. In this case, the substrate
used is
dipped into a bath containing the composition (B).
Preferably, contacting step (2) is performed by at least partially dipping the
substrate
into a bath containing the aqueous lubricant composition (B) having a bath
temperature in the range of from 20 to 95 C, preferably of from 45 to 90 C,
in
particular of from 50 to 85 C.
The treatment time, i.e., the period of time the surface is contacted with the
aqueous
composition (B) used in step (2) is preferably from 15 seconds to 20 minutes,
more
preferably from 30 seconds to 15 minutes, and most preferably 45 seconds to 10
minutes.
Preferably, no rinsing step is performed after having carried out step (2).
zo Composition (B)
The term "aqueous" with respect to composition (B) in the sense of the present
invention preferably means that the composition (B) is a composition
containing at
least 40 or at least 50 wt.-%, preferably at least 60 wt.-%, more preferably
at least 70
wt.-% in particular at least 80 wt.-%, most preferably at least 90 wt.-% or 95
wt.-% or
98 wt.-% or 99 wt.-% or even 100 wt.-% of water, based on its total content of
organic
and inorganic solvents including water. Thus, the composition (B) may contain
at
least one organic solvent besides water - however, in an amount significantly
lower
than the amount of water present. Preferably, composition (B) is free of
organic
solvents. Thus, preferably water is the only solvent/diluent present.
Preferably, composition (B) contains water in an amount of at least 40 wt.-%.
More
preferably, composition (B) contains water in an amount of at least 45 wt.-%
or at
least 50 wt.-%, more preferably of at least 60 wt.-%, even more preferably of
at least
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70 wt.-% and still more preferably of at least 80 wt.-%, in each case based on
the
total weight of composition (B).
Aqueous lubricant composition (B) has a pH value, which is in the non-neutral
pH
5 range, wherein the neutral pH range is a pH range of from >6.0 to <8Ø
In other
words, aqueous lubricant composition (B) has a pH value of either pH 7.0+1.0
or
higher, i.e., a pH value in a range of from 8.0 to 14.0, or a pH value of pH
7.0-1.0 or
lower, i.e., a pH value in a range of from 0 to 6.0 such as of from 0.1 to
6Ø If
composition (B) has a pH value in a range of from 8.0 to 14.0 it represents an
1.0 alkaline composition. If composition (B) has a pH value in a range of
from 0 to 6.0
such as of from 0.1 to 6.0 it represents an acidic composition. The pH value
can be in
particular adjusted by selecting constituent (b4) and its amount.
Preferably, aqueous lubricant composition (B) has a
pH value in a range of from 0.1 to 6.0, preferably of from 0.2 to 5.8, more
preferably
of from 0.5 to 5.5, preferably (i) when at least one of oxalate anions and
phosphate
anions are present as constituent (b4), in particular when the surface of the
substrate
is at least partially made of steel and/or an alloy thereof,
or has a
pH value in a range of from 8.0 to 14.0, preferably of from 9.0 to 14.0, more
preferably of from 10.0 to 13.5, even more preferably of from 11.0 to 13.0,
preferably
when (ii) calcium cations, chloride anions and hydroxide anions are present as
constituent (b4), in particular when the surface of the substrate is at least
partially
made of aluminum and/or an alloy thereof.
More preferably, the aqueous lubricant composition (B) has a
pH value in a range of from 0.1 to <2.0, even more preferably of from 0.2 to
1.9, still
more preferably of from 0.5 to 1.8, preferably when (i) at least oxalate
anions are
present as constituent (b4), more preferably when oxalate anions are present
as
constituent (b4) and no phosphate anions are present or - if present - are
present in
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an amount in g/I lower than the amount of oxalate anions in g/I, in particular
when the
surface of the substrate is at least partially made of steel and/or an alloy
thereof,
or has a
pH value in a range of from to 6.0, even more preferably of from
2.2 to 5.8, still
more preferably of from 2.4 to 5.5, preferably (i) when at least phosphate
anions are
present as constituent (b4), more preferably when phosphate anions are present
as
constituent (b4) and no oxalate anions are present or - if present - are
present in an
amount in g/I lower than the amount of phosphate anions in g/I, in particular
when the
surface of the substrate is at least partially made of steel and/or an alloy
thereof, or
has a
pH value in a range of from 8.0 to 14.0, even more preferably of from 9.0 to
14.0, still
more preferably of from 10.0 to 13.5, yet more preferably of from 11.0 to
13.0,
preferably (ii) when calcium cations, chloride anions and hydroxide anions are
present as constituent (b4), more preferably when calcium cations, chloride
anions
and hydroxide anions are present as constituent (b4) and none of oxalate
anions and
phosphate anions are present or - if present - are each present in an amount
in g/I
zo lower than the amount of each of calcium cations, chloride anions and
hydroxide
anions in g/I, in particular when the surface of the substrate is at least
partially made
of aluminum and/or an alloy thereof.
Preferably, composition (B) is present in the form of a solution or
dispersion, in
particular in the form of a solution, preferably at a temperature of at least
40 C, in
particular at least 50 C.
Preferably, composition (B) has a solid content in the range of from 0.1 to 30
wt.-%,
more preferably in the range of from 0.2 to 25 wt.-%, even more preferably in
the
range of from 0.3 to 20 wt.-%, still more preferably in the range of from 0.4
to 15
wt.-%, in each case based on the total weight of composition (B).
Since composition (B) comprises at least one of (i) oxalate and/or phosphate
anions
or (ii) calcium cations, chloride anions and hydroxide anions as constituent
(b4), it
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represents an oxalating composition, phosphating composition or aluminate
forming
composition, which is suitable of forming a conversion coating on the surface
of a
substrate. Since composition (B) further comprises (b2) at least one wax and
at least
one film-forming polymer (b1) it anyhow also represents a lubricant
composition at
the same time, which is suitable of forming a lubricating coating on the
surface of a
substrate.
Preferably, composition (B) does not comprise any oils such as lubricating
oils. In
particular, composition (B) does not comprise any further lubricating aids
besides
constituents (b1) and (b2).
Composition (B) comprises besides water at least constituents (b1) to (b4) and
optionally (b5), which are different from one another.
Constituent (b1)
Composition (B) comprises at least one film-forming polymer, which is a
homopolymer and/or copolymer being prepared by polymerization of at least
vinyl
pyrrolidone as at least one monomer, wherein said homopolymer and/or copolymer
zo has a polydispersity index (PDI) in a range of from 1.5 to 8Ø PDI as
well as the
weight average molecular weight (Mw) are determined according to the method
disclosed hereinafter in the 'methods' section.
Preferably, film-forming polymer (b1) has a polydispersity index (PDI) in a
range of
zs from 1.8 to 7.5, more preferably of from 2.0 to 7.0, still more
preferably of from 2.5 to
6.5, even more preferably of from 3.0 to 6.0, in particular of from 3.5 to
5.5.
Preferably, film-forming polymer constituent (b1) has a weight average
molecular
weight in the range of from 1 000 to 500 000 g/mol, more preferably of from 2
500 to
30 400 000 g/mol, even more preferably of from 4 000 to 300 000 g/mol,
still more
preferably of from 5 500 to 200 000 g/mol, yet more preferably of from 7 000
to
100 000 g/mol, still more preferably of from 8 500 to 75 000 g/mol.
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Preferably, film-forming polymer (b1) has at least one glass transition
temperature
(Tg) in a range of from 40 to 200 C, more preferably of from 50 to 190 C,
yet more
preferably of from 60 to 170 C, still more preferably of from 70 to 150 C,
even more
preferably of from 80 to 130 C, in particular of from 90 to 120 C. Tg is
determined
according to the method disclosed hereinafter in the 'methods' section.
Preferably, the at least one film-forming polymer is water-soluble or water-
dispersible,
more preferably water-soluble. Preferably, the at least one film-forming
polymer is
soluble or dispersible, more preferably soluble, in composition (B).
In case the at least one film-forming polymer (b1) is a copolymer at least one
further
monomer bearing at least one ethylenically unsaturated group, preferably at
least
one vinyl group, and being different from vinyl pyrrolidone can be used for
preparing
constituent (b1). Preferably, at least one further vinyl monomer different
from vinyl
pyrrolidone is used. However, such further monomers may also or alternatively
bear
at least one (meth)acrylate group. This includes (meth)acrylic acid groups.
Preferably, however, no monomers with acid groups are used. The further
monomer
can be an ionomer. The further monomer can also be ethylene, propylene,
butylene,
styrene etc. The term "(meth)acryl" means "acryl" and/or "methacryl".
Similarly,
zo "(meth)acrylate" means acrylate and/or methacrylate.
Preferably, film-forming polymer (bl ) is a homopolymer being prepared from
vinyl
pyrrolidone or a copolymer being prepared from vinyl pyrrolidone and at least
from at
least one monomer selected from the group consisting of (meth)acrylate
monomers,
vinyl amine, vinyl alcohol, vinyl formamide, vinyl caprolactam, vinyl acetate
and vinyl
imidazole. Preferably, the amount of structural units derived from the at
least one
further monomer different from vinyl pyrrolidone in the copolymer is 50 mol-%
at
most. Preferably, the amount of structural units derived from vinyl
pyrrolidone in the
copolymer is 50 mol-% at least and more preferably is at least 60 mol-% or at
least
70 mol-% or at least 75 mol-%.
Most preferred are polyvinyl pyrrolidone homopolymers and copolymers of vinyl
pyrrolidone and vinyl acetate. An exemplary polymer is Sokalane K 17P, from
BASF
SE, Germany.
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Preferably, the at least one film-forming polymer (b1) is present in the
composition
(B) in an amount in the range of from 0.05 to 20 wt.-%, more preferably in the
range
of from 0.10 to 15 wt.-%, even more preferably in the range of from 0.15 to 10
wt.-%,
still more preferably in the range of from 0.20 to 7.5 wt.-%, in particular of
from 0.25
to 5.0 wt.-%, in each case based on the total weight of the composition (B).
Constituent (b2)
Composition (B) comprises at least one wax as constituent (b2), which is
different
from constituent (b1).
As the term "wax" already implies, the at least one wax is a solid substance
at room
temperature (23 C). A person skilled in the art is familiar with the term
"wax". Said
term is, e.g., defined in by the German Society for Fat Science (DGF) within
DGF
standard method M-I 1 (75) (2015). Preferably, the at least one wax used as
constituent (b2) satisfies this definition of a wax. Waxes according to this
definition
can be kneaded at 20 C, have a firm (solid) to brittle hardness, have a
coarse to fine
crystalline structure, are translucent to opaque in color but not glassy or
glass-like,
zo melt without decomposition at temperatures above 40 C, are slightly
liquid above
their melting point and have a low viscosity above their melting point, have a
highly
temperature-dependent consistency and solubility, and can be polished under
light
pressure. Preferably and according to the definition of the DGF (DGF standard
method M-I 1 (75)), a substance is not a wax if it does not meet more than one
of the
above properties.
Preferably, the at least one wax (b2) is water-soluble or water-dispersible,
more
preferably water-dispersible. Preferably, the at least one wax (b2) is soluble
or
dispersible in composition (B).
Preferably, composition (B) is obtainable by using an aqueous dispersion or
solution
of the at least one wax (b2) for its preparation.
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Preferably, the at least one wax (b2) has a melting point in the range of from
30 C to
170 C, more preferably in the range of from 40 C to 165 C, especially
preferred in
the range of from 60 C to 160 C.
5 Composition (B) preferably comprises more than one wax as constituent
(b2).
Preferably, composition (B) comprises at least two, more preferably at least
three
different waxes as constituents (b2). Preferably, the at least two or at least
three
different waxes differ from each other at least in their melting temperature
(melting
point). Preferably, the difference between melting points of at least two of
the waxes
10 is at least 20 C.
Preferably, the at least one wax (b2) is present in the composition (B) in an
amount in
the range of from 0.1 to 20 wt.-%, more preferably in the range of from 0.5 to
15 wt.-
%, even more preferably in the range of from 0.75 to 12.5 wt.-%, still more
preferably
15 in the range of from 1.0 to 10.0 wt.-%, in particular of from 1.5 to 9.0
wt.-%, most
preferably in the range of from 2.0 to 7.5 wt.-%, in each case based on the
total
weight of the composition (B).
Preferably, the at least one wax (b2) is selected from the group consisting of
cationic
zo waxes, cationically stabilized waxes and non-ionic waxes. A
"cationically stabilized
wax" is preferably a wax that is stabilized by cationic groups in acidic
medium such
as in the composition (B) or is stabilized by at least one cationic
surfactant.
Preferably, the at least one wax (b2) is stabilized by at least one
emulsifier. For
example, the at least one wax (b2) can be stabilized by a cationic emulsifier
(cationically stabilized) or can be stabilized by a non-ionic emulsifier (non-
ionically
stabilized). Examples of cationic emulsifiers are alkoxylated such as
ethoxylated
stearyl amine and/or polyalkoxylated such as polyethoxylated tallow amine.
Examples of non-ionic emulsifiers are alcohols including for example
diethylaminoethanol.
Preferably, the at least one wax (b2) is selected from the group consisting of
polyolefin waxes (including polyethylene waxes, in particular HDPE (high
density
polyethylene) and/or polypropylene waxes, natural waxes including plant and
animal
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waxes such as montan waxes, bees waxes and/or carnauba waxes, paraffin waxes
(petroleum derived waxes) and mixtures thereof.
In this context, the term "olefin" mainly refers to alkenes typical of
polyolefins,
preferably alkenes with 2 to 8, especially alkenes with 2 to 6 and especially
alkenes
with 2 to 4 carbon atoms, especially those with a terminal double bond. In the
context
of this invention, preferred representatives are ethylene, propylene, 1-butene
and
isobutene. Ethylene and propylene are particularly preferred olefin monomers
in the
context of this invention. The term "polyolefin" is generally understood to
mean
homopolymers of a single type of olefin monomer (e.g., ethylene homopolymers)
or
copolymers of at least two olefin monomers (e.g. polymers of mixtures
comprising or
consisting of ethylene, propylene, 1-butene and/or isobutene). Polyolefins
thus
contain one or more types of olefin monomers and are therefore homopolymers or
copolymers. However, they may also additionally contain one or more
ethylenically
unsaturated monomers other than olefin monomers, in particular ethylenically
unsaturated monomers bearing carboxylic acid groups, polymerized or grafted.
If
different ethylenically unsaturated monomers with carboxyl groups or
carboxylic acid
anhydride groups are used for the purpose of polymerization or grafting of the
olefin
monomers, this is done in an amount such that the polyolefin wax as
constituent (a5)
zo containing carboxyl groups has an acid number in the range from 3 to 50,
preferably
from 5 to 40, particularly preferably from 8 to 35, very particularly
preferably from 10
to 25 and particularly preferably from 13 to 20 mg KOH/g. Polyolefin waxes are
preferably selected from the group consisting of oxidized polyethylene waxes,
oxidized polypropylene waxes, oxidized poly(ethylene-co-propylene) waxes and
oxidized ethylene-olefin copolymers, ethylene-(meth)acrylic acid copolymers
and
polymers of ethylene and/or propylene other than the abovementioned
copolymers,
which have been grafted, for example, with maleic anhydride (converted into
the
hydrolyzed form, and carrying free COOH groups). Of course, other
ethylenically
unsaturated acids such as acrylic acid can also be used for grafting.
The paraffin waxes used are preferably microcrystalline.
Exemplary waxes that are commercially available and that can be used are, e.g.
Aquacer 1041 from BYK Chemie, Germany, Aquacer 561 from BYK Chemie,
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Aquacer 517 from BYK Chemie, WOkonil 0-33a from MCinzing Chemie and
Licowax KST from Clariant, Germany,
Constituent (b3)
Composition (B) comprises at least one defoamer as constituent (b3).
Preferably, the
defoamer is free of silicone. Thus, no siloxane and/or polysiloxane units are
preferably present in (b3).
Preferably, (b3) is present in composition (B) in an amount of from 0.01 to
5.0 wt.-%,
more preferably of from 0.01 to 4.0 wt.-%, even more preferably of from 0.01
to 3 wt.-
%, in particular of from 0.05 to 1.5 wt.-%, in each case based on the total
weight of
composition (B).
Constituent (b4)
Composition (B) comprises (i) at least one of oxalate anions and phosphate
anions or
comprises (ii) calcium cations, chloride anions and hydroxide anions as
constituent(s)
(b4). Preferably, composition (B) comprises precisely one of oxalate anions
and
phosphate anions, i.e., either oxalate or phosphate ions, or comprises calcium
cations, chloride anions and hydroxide anions.
Oxalate and/or phosphate anions are preferably present in composition (B) as
(b4),
when the pH value of composition (B) is in the non-neutral acidic range up to
pH 6Ø
zs Calcium cations, chloride anions and hydroxide anions are preferably
present in
composition (B) as (b4), when the pH value of composition (B) is in the non-
neutral
alkaline range having a pH value of 8.0 or higher.
Preferably, oxalate anions (b4) are present in the composition (B) in an
amount in the
range of from 2 to 500 g/I, more preferably of from 5 to 100 g/I, in
particular of from
10 to 50 g/I of oxalic acid, calculated in each case as oxalic acid dihydrate.
In this
case, preferably no additional phosphate anions are present.
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As outlined hereinbefore in case oxalate anions (b4) are present in the
composition
(B), composition (B) preferably has a pH value in a range of from 0.1 to <2.0,
even
more preferably of from 0.2 to 1.9, still more preferably of from 0.5 to 1.8.
This in
particular applies when oxalate anions are present as sole constituent (b4)
and no
phosphate anions are present or - if phosphate anions present - if these are
present
in an amount in g/I lower than the amount of oxalate anions in g/I, in
particular when
the surface of the substrate is at least partially made of steel and/or an
alloy thereof.
In the sense of the present invention, "oxalic acid" also means the single and
double
deprotonated form of oxalic acid. Likewise, in the sense of the present
invention,
"oxalate" also means the single and double protonated form thereof, the double
protonated from being oxalic acid. Preferably, oxalic acid dihydrate is used,
as is it
cheap and less hygroscopic.
Preferably, phosphate anions (b4) are present in the composition (B) in an
amount in
the range of from 2 to 500 g/I, particularly preferably in the range from 4 to
320 g/I,
most particularly preferably in the range from 8 to 200 g/I, in particular in
the range
from 12 to 120 g/I, calculated in each case as PO4. In this case, preferably
no
additional oxalate anions are present.
As outlined hereinbefore in case phosphate anions (b4) are present in the
composition (B), composition (B) preferably has a pH value in a range of from
to
6.0, even more preferably of from 2.2 to 5.8, still more preferably of from
2.4 to 5.
This in particular applies when phosphate anions are present as sole
constituent (b4)
and no oxalate anions are present or - if oxalate anions present - if these
are present
in an amount in g/I lower than the amount of phosphate anions in g/I, in
particular
when the surface of the substrate is at least partially made of steel and/or
an alloy
thereof.
If, in connection with weight concentrations (e.g., g/1), the term "calculated
as X" is
used, where X is a specific, specified chemical compound, this is to be
understood as
follows: If an alternative chemical compound (not X) it should be used in such
a
molar concentration as calculated for X, taking into account its molar mass,
from the
specific weight concentration (e.g.õ g/1) indicated in each case.
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Preferably, calcium cations are present in the composition (B) as part of (b4)
in an
amount in the range of from 0.05 to 15.0 g/I, more preferably of from 0.07 to
10.0 g/I,
even more preferably of from 0.10 to 7.5 g/I, in particular of from 0.20 to
5.0 g/I, yet
more preferably of from 0.30 to 2.5 g/I, in particular of from 0.40 to 2.0 g/I
or of from
0.50 to 1.5 g/I, calculated in each case as metal. Preferably, chloride anions
are
present in the composition (B) as part of (b4) in an amount in the range of
from 0.10
to 15.0 g/I, more preferably of from 0.50 to 10.0 g/I, even more preferably of
from
0.70 to 7.0 g/I, in particular of from 0.80 to 5.0 g/I, yet more preferably of
from 0.9 to
4.0 g/I, in particular of from 1.0 to 3.0 g/I, calculated in each case as
sodium chloride.
Preferably, hydroxide anions are present in the composition (B) as part of
(b4) in an
amount in the range of from 0.01 to 6.0 g/I, more preferably of from 0.02 to
5.0 g/I,
even more preferably of from 0.03 to 3.0 g/I, in particular of from 0.04 to
1.5 g/I, yet
more preferably of from 0.05 to 0.8 g/I, in particular of from 0.10 to 0.6
g/I, calculated
in each case as sodium hydroxide.
As outlined hereinbefore in case calcium cations, chloride anions and
hydroxide
anions (b4) are present in the composition (B), composition (B) preferably has
a pH
value in a range of from 8.0 to 14.0, even more preferably of from 9.0 to
14.0, still
zo more preferably of from 10.0 to 13.5, yet more preferably of from 11.0
to 13Ø This in
particular applies when calcium cations, chloride anions and hydroxide anions
are
present as sole constituent (b4) and none of oxalate anions and phosphate
anions
are present or - if oxalate anions and/or phosphate anions present - if these
are each
present in an amount in g/I lower than the amount of each of calcium cations,
chloride anions and hydroxide anions in g/I, in particular when the surface of
the
substrate is at least partially made of aluminum and/or an alloy thereof.
Optional constituent (b5)
Composition (B) may optionally comprise Fe(III) ions (i.e. iron(III) cations)
as
constituent (b5). In case oxalate anions are present as constituent (b4),
constituent
(b5) is necessarily present in composition (B).
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Fe(III) ions as constituent (b5) are used as oxalating accelerator. A source
of iron(III)
cations in the sense of the present invention is preferably a water soluble
iron(III) salt
such as iron(III) nitrate. Also, a water soluble iron(II) salt in combination
with an
oxidizing agent suitable for the production of iron(III) cations can be used
as a source
5 of iron(III) cations.
Preferably, the content of iron(III) is in the range of from 0.0004 to 2 g/I,
more
preferably of from 0.04 to 2 g/I and especially preferred from 0.4 to 2 g/I,
calculated
as iron(III) nitrate.
1.0
Preferably, composition (B) does not comprise nitroguanidine when oxalate
anions
are present therein.
Optional constituent (b6)
Composition (B) may further comprise at least one corrosion inhibitor as
optional
constituent (b6), which is preferably different from each of constituents (b1)
to (b4)
and optional constituent (b5).
zo The term "corrosion inhibitor" is a term known to a person skilled in
the art. Said term
is for instance defined in ROmpp Lexikon, Lacke und Druckfarben 1998, Georg
Thieme Verag, 10. Auflage".
Preferably, corrosion inhibitors for use as constituent (b6) are alkyl amides,
amines
and alkanol amines. Examples of suitable constituents (b6) are morpholine,
benzylamine, butindiol, diisopropylamine nitrite, morpholine nitrite, 2-(2-
heptadec-8-
eny1-2-imidazolin-1-yl)ethanol, dicyclohexylamine nitrite, cyclohexylamine
benzoate,
dicyclohexylamine caprylate, guanadine chromate, hexamethyleneimine benzoate,
dicyclohexylamine benzoate, ethylaniline, mercaptobenzotriazole, pyridine,
rosin
amine, phenylacridine, hexamethylentetram in, nonylphenoxyacetic acid,
succinic acid
semi-ester and alkindiols such as butindiol.
Preferably, the at least one corrosion inhibitor is present in composition (B)
is
preferably in an amount of from 0.01 to 5.0 wt.-%, more preferably of from
0.05 to 4.0
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wt.-%, even more preferably of from 0.1 to 3 wt.-%, in particular of from 0.1
to 1.5 wt.-
%, in each case based on the total weight of composition (B).
Optional constituent (b7)
Composition (B) may further comprise at least one optional constituent (b7),
which is
at least one phosphatizing accelerator when (B) comprises phosphate anions as
constituent (b4), and which is preferably different from each of constituents
(b1) to
(b4) and optional constituents (b5) and (b6). Preferably, nitrate used as (b7)
and is
present in an amount in the range from 1 to 600 g/I, particularly as nitrate
anions,
particularly preferably in the range from 4 to 450 g/I, most particularly
preferably in
the range from 8 to 300 g/I, in particular in the range from 16 to 200 g/I.
In particular when (B) comprises phosphate anions as constituent (b4),
additional or
alternative accelerators are selected from the group consisting of chlorate,
guanidine,
hydroxylamine, nitrite, nitrobenzene, sulfonate, perborate, peroxide,
peroxysulfuric
acid and other accelerators containing nitro groups. A low or moderate content
of
nitrate can have an accelerating effect on electrolytic phosphating and can
therefore
be advantageous.
In particular when (B) comprises phosphate anions as constituent (b4),
composition
(B) may further comprise at least one constituent selected from the group
consisting
of organic acids and phosphonic acids and the salts and esters thereof in the
range
from 0.1 to 200 g/I, particularly preferably in the range from 1 to 150 g/I,
most
particularly preferably in the range from 3 to 100 g/I, in particular in the
range from 6
to 70 g/I. These constituents may act in particular as complexing agents.
In particular when (B) comprises phosphate anions as constituent (b4),
composition
(B) may further comprise at least one cation selected from the group
consisting of Zn,
Mg, Ca, Ni, Cu and/or Mn, preferably in the range from 4 to 100 g/L,
particularly
preferable in the range from 5 to 60 g/L, most particularly preferably in the
range from
8 to 50 g/L.
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The content of cations and anions mentioned herein with respect to composition
(B)
can be monitored and determined by the means of ICP-OES (optical emission
spectroscopy with inductively coupled plasma). Said method is described
hereinafter
in detail. The content of free fluoride anions is, however, determined by
means of a
fluoride electrode.
Optional constituent (b8)
Optionally, composition (B) may comprise at least one further constituent
(b8). Said
at least one further constituent (b8) is preferably selected from the group
consisting
of thickeners, pigments, fillers, surfactants and mixtures thereof.
Constituent(s) (b8)
may be present in amount of from 0.01 to 10 wt.-% in composition (B), based on
the
total weight of composition (B). Preferably, optional constituent (b8) is
different from
each of constituents (b1) to (b4) and optional constituents (b5), (b6) and
(b7).
Examples of thickeners are polysaccharide, polysiloxane, polyvinlyamide,
polyacrylamide and polyglycol.
Examples of pigments and fillers are boron nitride, graphite and molybdenum
sulfide.
However, as in particular graphite and molybdenum sulfide are solid lubricants
and
their use is related to disadvantages as outlined in the introductory part,
preferably no
such pigments, in particular neither graphite nor molybdenum sulfide, is
present in
composition (B).
zs Examples of surfactants are fatty alcohol alkoxylates and especially
fatty alcohol
ethoxylates.
Optional step (3)
Optional step (3) of the inventive method is a step, wherein the coating film
obtained
after step (2) is optionally dried.
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The drying step (3) may be preferably performed, e.g. at a temperature in the
range
of 15 C to 100 C, more preferably at a temperature in the range of 18 C to 95
C, in
particular at a temperature in the range of 20 C to 90 C.
Inventive pretreated substrate
A further subject-matter of the present invention is a pretreated metallic
substrate
obtainable by the inventive method.
All preferred embodiments described above herein in connection with the
inventive
method of pretreatment are also preferred embodiments of pretreated substrate.
The
same applies, of course, to the embodiments of the substrate as such as
outlined
hereinbefore in connection with step (1) of the inventive method.
The coating film obtained after step (2) or optionally after step (3) is a
combined
conversion and lubricant coating film. Thus, the coating film obtained
combines the
properties of a conversion layer and a lubricant layer.
Preferably, the pretreated metallic substrate obtainable by the inventive
method
contains a conversion coating film obtained by performing step (2) and further
contains a lubricant coating film on top of said conversion coating film also
obtained
by performing step (2). However, it is also possible that the coating film
obtained after
step (2) or optionally after step (3) is chemically heterogeneous.
zs Preferably, the coating film present on the surface of the substrate
after having
performed step (2) and optionally step (3) has a coating weight in a range of
from 1.0
to 40.0 g/m2, preferably in a range of from 5.0 to 35.0 g/m2, more preferably
in a
range of from 10.0 to 30.0 g/m2. The method for determining the coating weight
is
disclosed in the example section.
Inventive cold forming method
A further subject-matter of the present invention is a method of cold forming
a
metallic substrate, characterized in that it comprises a step of subjecting
the inventive
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pretreated metallic substrate according to a cold forming process, preferably
by
drawing.
All possible cold forming processes known in the prior art can be carried out,
in
particular rolling such as thread rolling or beating, e.g. for nut or bolt
blanks,
drawing, in particular sliding drawing (tensile compression forming), e.g. of
welded or
seamless tubes, hollow sections, solid sections, wires or rods, e.g. during
wire
drawing or tube drawing, or deep-drawing, e.g. of strips or sheet metal,
pressing
such as cold extrusion (pressure forming), e.g. of hollow or solid bodies,
stretch
forming (forming to gauge block/final size) and/or cold upsetting, e.g. from
wire
sections to fasteners such as nuts.
The most common shaped bodies to be formed from the inventive pretreated
metallic
substrates are strips, sheets, slugs, wires, wire coils, more complicated
shaped parts,
sleeves, profiles such as hollow or solid profiles, tubes, discs, discs, rods,
bars or
cylinders.
Preferably, the cold-formed substrate obtained after the cold forming process
still
bears at least part of the coating film obtained after having performed step
(2) and
zo optionally step (3): Due to the amount of the coating weight of the
coating film
obtained after step (2) or optionally step (3) present on the pretreated
substrate, said
coating film "survives" conventional cold forming processes. For example, this
leaves
at least 10 %, preferably at least 15 %, particularly preferred at least 20 %
of the
coating weight on a pretreated and cold formed substrate after cold forming,
in
particular if the substrate has undergone a drawing.
However, the coating film may be removed from the cold formed substrate, e.g.,
by
using an aqueous cleaning composition. Thus, after the cold forming process,
the
obtained substrate is preferably cleaned, in order to remove the conversion
and
lubricant coating film from the substrate, e.g. by means of alkaline cleaners,
acids or
pickling agents.
Inventive composition (B)
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A further subject-matter of the present invention is an aqueous lubricant
composition
(B) as defined hereinbefore in connection with the inventive pretreatment
method.
All preferred embodiments described above herein in connection with the
inventive
5 method and the composition (B) used in step (2) thereof and the
constituents
contained therein are also preferred embodiments of the inventive composition
(B).
Inventive master batch
10 A further subject-matter of the present invention is a master batch to
produce the
inventive aqueous composition (B) by diluting the master batch with water and
if
applicable by adjusting the pH value.
All preferred embodiments described above herein in connection with the
inventive
15 methods and the inventive composition (B) and the constituents contained
therein
are also preferred embodiments of inventive master batch.
If a master batch is used to produce the aqueous composition (B) according to
the
present invention, the master batch typically contains the constituents of the
aqueous
zo composition (B) to be produced in the desired proportions, but at a higher
concentration. Such master batch is preferably diluted with water to the
concentrations of constituents as disclosed above to form the aqueous
composition
(B). If necessary, the pH value of the aqueous composition (B) may be adjusted
after
dilution of the master batch.
Of course, it is also possible to further add any of the optional components
to the
water, wherein the master batch is diluted or to add any of the optional
components
after diluting the master batch with water. It is however preferred that the
master
batch already contains all necessary components.
Preferably, the master batch is diluted with water and/or an aqueous solution
in the
ratio of 1:5,000 to 1:10, more preferred 1:1,000 to 1:10, most preferred in
the ratio of
1:300 to 1:10 and even more preferred 1:150 to 1:50 to produce composition
(B).
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METHODS
1. Total acid (TA)
The total acid (TA) is the sum of the divalent cations present as well as free
and
bound oxalic acids and/or phosphoric acid. It is determined by the consumption
of 0.1
M NaOH using a pH meter and an electrode. For this, 10 ml of the composition
are
pipetted into a suitable vessel, for example a 300 ml Erlenmeyer flask and
diluted
with 25 ml of deionized water. It is then titrated with 0.1 M NaOH to a pH of
9. The
consumption in ml per 10 ml of the diluted composition corresponds to the
total acid
score (TA).
2. Free Acid (FA) and Fischer total acid (TAF)
The free acid (FA) is determined by the consumption of 0.1 M NaOH using a pH
meter and an electrode. For this, 5 ml of the composition are pipetted into a
suitable
vessel, for example a 300 ml Erlenmeyer flask and diluted with 50 ml of
deionized
water. It is then titrated with 0.1 M NaOH to a pH of 4. The consumption in ml
per 10
ml of the diluted composition corresponds to the free acid score (FA). After
FA
titration, 40 mL of 30% potassium oxalate solution is added into the solution.
It is then
titrated with 0.1 M NaOH to a pH of 9. The consumption in ml per 10 ml of the
diluted
zo composition corresponds to the Fischer total acid score (TAF)
3. Solid content
The non-volatile fraction (solids or solid content) is determined in
accordance with
DIN EN ISO 3251 (date: June 2019). This involves weighing out 1 g of sample
into
an aluminum dish which has been dried beforehand and drying the dish with
sample
in a drying cabinet at 130 C for 60 minutes, cooling it in a desiccator, and
then
reweighing. The residue, relative to the total amount of sample employed,
corresponds to the nonvolatile fraction.
4. ICP-OES
The amount of certain elements in a sample under analysis is determined using
inductively coupled plasma atomic emission spectrometry (ICP-OES) according to
DIN EN ISO 11885 (date: September 1,2009).
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4. Alkaline points
The alkaline points are determined by consumption of 0.05 M sulphuric acid
using a
pH meter and an electrode. For this, 5 ml of the composition are pipetted into
a
suitable vessel, for example a 300 ml Erlenmeyer flask and diluted with 50 ml
of
deionized water. It is then titrated with 0.05 M sulphuric acid to a pH of
4.5.
5. Calcium points
The calcium points are determined by titration of 0.1 M EDTA solution.
1.0 6. Glass transition temperature (-10)
Glass transition temperature (Tg) is determined through differential scanning
calorimetry (DSC). 10 mg of a polymer sample is analyzed by DSC. The
temperature-program is set from -50 C to 210 C and the heating/cooling rate
is
selected to be 10 C/M in.
7. Polvdispersity index (PDI) and weiqht averaqe molecular weiqht (Mw)
Determination of Mw (weight average molecular weight) and PDI as well as of Mn
(number average molecular weight) is performed by gel permeation
chromatography
(GPC), equipped with a RI and UV detector. Polymer samples are dissolved in
the
zo mobile phase and the resulting solutions are filtrated with a Millipore
filter 0.45 pm.
Eluting conditions are the following ones. Mobile phase: DMF 100% vol. 0.01 %
LiBr;
flow rate: 1 mL/min; columns: Varian Aquagel OH mixed H, 8 pm, 3*30 cm;
detection:
RI (concentration detector Agilent) + UV at 290 nm; samples concentration:
around
0.5 wt% in the mobile phase; injection loop: 100 pL.
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EXAMPLES
The following examples further illustrate the invention but are not to be
construed as
limiting its scope.
1. Inventive and comparative lubricant compositions
1.1 Example 1.1 (inventive)
An acid stable phosphate anions containing aqueous polymeric lubricant
composition
11 for steel and/or steel alloy pretreatment was prepared in a high-speed
mixer with
stirring. The composition of this lubricant is given in Table 1. It has a pH
value of
about 2.5.
Table 1: Composition of phosphate containing lubricant example 11
Constituent Amount [wt.-%]
Polymer 1 0.3
Aqueous polymer solution 2 (30 wt.-% solids) 0.1
Aqueous wax dispersion 1 (40 wt.-% solids) 2.7
Aqueous wax dispersion 2 (45 wt.-% solids) 3.6
Aqueous wax dispersion 3 (40 wt.-% solids) 2.1
Wax 4 0.5
Polyglycol 0.1
Silicone-free defoamer 0.2
Corrosion inhibitor 0.1
Gardobond Z 3100 9.4
Deionized water 80.9
100.0
Polymer 1 is a polyvinyl pyrrolidone homopolymer, which is commercially
available
from BASF SE. Polymer 1 has a polydispersity index (PDI) of about 4.5 and a
glass
zo transition temperature (Tg) of about 100 to 110 C. Aqueous polymer
solution 2
contains a polyvinyl pyrrolidone copolymer, which is commercially available
from
BASF SE. Aqueous wax dispersion 1 contains a polypropylene wax, which is
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commercially available from BYK Chemie. Aqueous wax dispersion 2 contains a
polyethylene wax, which is commercially available from MOnzing Chemie. Aqueous
wax dispersion 3 contains a microcrystalline wax, which is commercially
available
from Michelman. Wax 4 is a montane wax, which is dispersible in aqueous
medium.
A mixture of an alkyl amide and an alkanolamine is used as corrosion
inhibitor.
Gardobond Z 3100 is a commercially available phosphate anions containing
product
from Chemetall GmbH, which is used for zinc phosphating. The phosphating point
(free acid (FA) plus Fischer total acid (TFA) of 11 is 20.
1.0 1.2 Example 12 (inventive)
An acid stable oxalate anions containing aqueous polymeric lubricant
composition 12
was prepared was prepared for steel and/or steel alloy pretreatment in a high-
speed
mixer with stirring. The composition of this lubricant is given in Table 2. It
has a pH
value of about 1Ø
Table 2: Composition of oxalate containing lubricant example 12
Constituent Amount [wt.-%]
Polymer 1 0.3
Aqueous polymer solution 2 (30 wt.-% solids) 0.1
Aqueous wax dispersion 1 (40 wt.-% solids) 2.8
Aqueous wax dispersion 2 (45 wt.-% solids) 3.8
Aqueous wax dispersion 3 (40 wt.-% solids) 2.2
Wax 4 0.6
Po lyg lycol 0.1
Silicone-free defoamer 0.2
Corrosion inhibitor 0.1
Gardoe Hybrid 4100 3.1
Gardobond Additive H 7104 2.2
Deionized water 84.5
100.0
zo Polymer 1, aqueous polymer solution 2, aqueous wax dispersions 1, 2 and
3, and
wax 4 as well as the corrosion inhibitor have been described above in
connection
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with lubricant example 11. Gardo Hybrid Z 4100 is a commercially available
oxalic
acid containing product (Chemetall GmbH), which is free from phosphates.
Gardobone Additive H 7104 is a Fe(NO3)3 containing commercially available
product from Chemetall GmbH and is used as an oxalating accelerator in
5 combination with Gardo Hybrid Z 4100.
The concentration of Gardo0 Hybrid Z 4100 in 12 is 33 g/L and the
concentration of
Gardobond Additive H 7104 in 12 is 23.6 g/L. The total acid (TA) value of 12
is 55.
10 1.3 Example 13 (inventive)
An acid stable phosphate anions containing aqueous polymeric lubricant
composition
13 was prepared was prepared for steel and/or steel alloy pretreatment in a
high-
speed mixer with stirring. The composition of this lubricant is given in Table
3. It has
a pH value of about 5.5.
Table 3: Composition of phosphate containing lubricant example 13
Constituent Amount [wt.-%]
Polymer 1 0.3
Aqueous polymer solution 2 (30 wt.-% solids) 0.1
Aqueous wax dispersion 1 (40 wt.-% solids) 2.7
Aqueous wax dispersion 2 (45 wt.-% solids) 3.6
Aqueous wax dispersion 3 (40 wt.-% solids) 2.1
Wax 4 0.5
Po lyg lycol 0.1
Silicone-free defoamer 0.2
Corrosion inhibitor 0.1
Gardobonde Z 3911 5.1
Gardobond Additive H 7201 0.3
Deionized water 85.0
100.0
zo Polymer 1, aqueous polymer solution 2, aqueous wax dispersions 1, 2 and
3, and
wax 4 as well as the corrosion inhibitor have been described above in
connection
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with lubricant example 11. Gardobone Z 3911 is a commercially available
phosphate
containing product from Chemetall GmbH, which is used for iron phosphating.
Gardobone Additive H 7201 is a commercially available additive for iron
phosphating. The total acid (TA) of 13 is 15 and alkaline point is 0.7.
1.4 Example 14 (inventive)
An alkaline stable aqueous polymeric lubricant composition 14 was prepared for
aluminum and/or aluminum alloy pretreatment in a high-speed mixer with
stirring. The
composition of this lubricant is given in Table 4. It has a pH value of about
12Ø
1.0
Table 4: Composition of lubricant example 14
Constituent Amount [wt.-%]
Polymer 1 0.3
Aqueous polymer solution 2 (30 wt.-% solids) 0.1
Aqueous wax dispersion 1 (40 wt.-% solids) 2.7
Aqueous wax dispersion 2 (45 wt.-% solids) 3.6
Aqueous wax dispersion 3 (40 wt.-% solids) 2.1
Wax 4 0.5
Po lyg lycol 0.1
Silicone-free defoamer 0.2
Corrosion inhibitor 0.1
Gardobond Z 3900 3.0
Deionized water 87.3
X 100.0
Polymer 1, aqueous polymer solution 2, aqueous wax dispersions 1, 2 and 3, and
wax 4 as well as the corrosion inhibitor have been described above in
connection
with lubricant example 11. Gardobone Z 3900 is a commercially available
product
from Chemetall GmbH comprising calcium chloride, sodium chloride and calcium
hydroxide. The calcium point of 14 is in a range of from 15 to 20.
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1.5 Example 15 (comparative)
The commercially available product Gardomer L 6332 from Chemetall GmbH has
been used as comparative composition 15, which is an aqueous alkaline and wax
containing polymeric lubricant. Gardomere L 6332 has a pH value of 9.5 and is
not
stable in acid solution. In Gardomere L 6332 an acid-functional copolymer not
containing any monomeric unit derived from vinyl pyrrolidone is used as film-
forming
polymer.
1.5 Example 16 (comparative)
An acid stable oxalate anions containing aqueous polymeric lubricant
composition 16
was prepared for steel and/or steel alloy pretreatment in a high-speed mixer
with
stirring. The composition of this lubricant and its pH value is identical to
the
composition and pH value of the lubricant of example 12 except that not
Gardobonde
Additive H 7104 has been used but instead a commercially available oxalating
accelerator comprising nitroguanidine.
2. Inventive and comparative method
2.1 Zinc-phosphating treatment and treatment with acid stable aqueous
polymeric
lubricant 11 for steel and/or steel alloy in a single step (inventive)
As metal workpieces the following substrates were used:
a) Sheet made of 2.0 mm hot-rolled steel (HRS) (DC11 (no. 1.0332); substrate
51),
b) Slugs with 27 mm diameter and 13 mm height made of tempered steel (C15 (no.
1.0401); substrate S2) and,
c) Wire sections with 11.0 mm diameter made of steel (C15 (no. 1.0401);
substrate
S3).
Each of the workpieces was dipped in a cleaning bath with a 50 g/L aqueous
cleaning solution of Gardoclean 351 available from Chemetall GmbH at 90 C for
10
min. and then rinsed by cold tap water for 1 min. Afterwards, the surface
purified
workpieces were then pickled by using a 15 wt.-% HCI solution for 1 min. and
subsequently rinsed by cold tap water for 1 min. The workpieces were then
optimally
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activated by Gardolenee V 6522 available from Chemetall GmbH at room
temperature for 1 min.
Then, in a single step, the workpieces were dipped into a bath containing
lubricant
example 11 at 60 C for 10 min.
Finally, the coated workpieces obtained were dried with air at 85 C.
No solid foams were formed during this process. The resulting sludge in the
reaction
1.0 bath of 11 was powdery and could be easily removed from the reaction
bath.
2.2 Oxalating treatment and treatment with acid stable aqueous polymeric
lubricant
12 (inventive) or 16 (comparative) for steel and/or steel alloy in a single
step
As metal workpieces the following substrates were used:
a) Sheet made of 0.8 mm cold-rolled steel (CRS) (DC05 (no. 1.0332); substrate
S4),
b) Sheet made of 2.0 mm hot-rolled steel (HRS) (DC11 (no. 1.0332); substrate
Si),
c) Slugs with 27 mm diameter and 13 mm height made of tempered steel (C15 (no.
1.0401); substrate S2 and,
d) Wire sections with 11.0 mm diameter made of steel (C15 (no. 1.0401);
substrate
S3).
Each of the workpieces was dipped in a cleaning bath with a 50 g/L aqueous
cleaning solution of Gardocleang 351 available from Chemetall GmbH at 85 C for
10
min. and then rinsed by cold tap water for 1 min. Afterwards, the surface
purified
workpieces were then pickled by using a 15 wt.-% HCI solution for 1 min. and
subsequently rinsed by cold tap water for 1 min.
Then, in a single step, the workpieces were dipped into a bath containing
lubricant
example 12 or 16 at 85 C for 8 min.
Finally, the coated workpieces obtained were dried with air at 85 C.
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No solid foams were formed during this process. The resulting sludge in the
reaction
baths of 12 and 16 was powdery and could be easily removed from the reaction
bath.
2.3 Iron-phosphating treatment and treatment with acid stable aqueous
polymeric
lubricant 13 for steel and/or steel alloy in a single step (inventive)
As metal workpieces the following substrates were used:
a) Sheet made of 2.0 mm hot-rolled steel (HRS) (DC11 (no. 1.0332); substrate
51),
b) Seamless tube made of steel (no. 1.0050, substrate S5)
Each of the workpieces was dipped in a cleaning bath with a 50 g/L aqueous
cleaning solution of Gardoclean 351 available from Chemetall GmbH at 85 C for
10
min. and then rinsed by cold tap water for 1 min. Afterwards, the surface
purified
workpieces were then pickled by using a 15 wt.-% HCI solution for 1 min. and
subsequently rinsed by cold tap water for 1 min.
Then, in a single step, the workpieces were dipped into a bath containing
lubricant
example 13 at 70 C for 10 min.
Finally, the coated workpieces obtained were dried with air at 85 C.
No solid foams were formed during this process. The resulting sludge in the
reaction
bath of 13 was powdery and could be easily removed from the reaction bath.
2.4 Treatment with alkaline stable aqueous polymeric lubricant 14 for aluminum
and/or aluminum alloy in a single step (inventive)
As metal workpieces the following substrates were used:
Slugs with 27 mm diameter and 13 mm height made of tempered aluminum (1050A,
substrate S6).
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Each of the workpieces was dipped in a cleaning bath with a 20 g/L aqueous
cleaning solution of Gardoclean T 5550 available from Chemetall GmbH at 55 C
for
10 min. and then rinsed by cold tap water for 1 min. Afterwards, the surface
purified
workpieces were then pickled by using a 35 g/L acid solution of Gardoacid P
4304
5 for 1 min. and subsequently rinsed by cold tap water for 1 min.
Then, in a single step, the workpieces were dipped into a bath containing
lubricant
example 14 at 75 C for 10 min.
10 Finally, the coated workpieces obtained were dried with air at 85 C.
No solid foams were formed during this process. The resulting sludge in the
reaction
bath of 14 was powdery and could be easily removed from the reaction bath.
15 2.5 Treatment of steel and/or steel alloy with a conventional alkaline
polymeric
lubricant /5 after performance of (i) a zinc phosphating treatment followed by
(ii)
rinsing in two steps (plus rinsing) (comparative)
As metal workpieces the following substrates were used:
a) Sheet made of 2.0 mm hot-rolled steel (HRS) (DC11 (no. 1.0332); substrate
S3),
b) Wire sections with 11.0 mm diameter made of steel (C15 (no. 1.0401);
substrate
Si).
Each of the workpieces was dipped in a cleaning bath with a 50 g/L aqueous
cleaning solution of Gardoclean 351 available from Chemetall GmbH at 85 C for
10
min. and then rinsed by cold tap water for 1 min. Afterwards, the surface
purified
workpieces were then pickled by using a 15 wt.-% HCI solution for 1 min. and
subsequently rinsed by cold tap water for 1 min. The workpieces were then
optimally
activated by Gardolene V 6522 available from Chemetall GmbH at room
temperature for 1 min.
The workpieces were dipped into a zinc-phosphating bath containing commercial
product Gardobonde Z 3100 from Chemetall GmbH at 60 C for 10 min. The
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phosphate point of this zinc-phosphating bath is 20, same as in case of
lubricant 11.
Then the zinc-phosphated workpieces were rinsed with tap water for
neutralization of
the surface. After rinsing, the workpieces were dipped into a bath containing
a
conventional comparative aqueous alkaline lubricant 15 at 60 C for 2 min.
Finally, the coated workpieces obtained were then dried with air at 85 C.
2.6 Treatment of steel and/or steel alloy with a conventional alkaline
polymeric
lubricant 15 after performance of (i) an oxalating treatment followed by (ii)
rinsing in
two steps (plus rinsing) (comparative)
a) Sheet made of 0.8 mm cold-rolled steel (CRS) (DC05 (no. 1.0332); substrate
S2),
b) Wire sections with 11.0 mm diameter made of steel (C15 (no. 1.0401);
substrate
Si).
Each of the workpieces was dipped in a cleaning bath with a 50 g/L aqueous
cleaning solution of Gardocleane 351 available from Chemetall GmbH at 85 C for
10
min. and then rinsed by cold tap water for 1 min. Afterwards, the surface
purified
workpieces were then pickled by using a 15 wt.-% HC1 solution for 1 min. and
zo subsequently rinsed by cold tap water for 1 min.
The workpieces were dipped into an oxalating bath containing commercial
product
Gardoe Hybrid Z 4100 and Gardobonde Additive H 7104 from Chemetall GmbH at
85 C for 10 min. The total acid (TA) of this oxalating bath is 55, same as 12.
Then the
oxalated workpieces were rinsed with tap water for neutralization of the
surface. After
rinsing, the workpieces were dipped into a bath containing a conventional
comparative aqueous alkaline lubricant 15 at 60 C for 2 min.
Finally, the coated workpieces obtained were then dried with air at 85 C.
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3. Properties of the coated substrates
3.1 Coated substrates obtained from the 1-step-process as outlined in item 2.1
(inventive) - use of lubricant II
The resulting coating layer on each of the coated workpieces is homogenous,
thick
and adhered firmly on the treated surface of each workpiece. The coating
layers
showed a very good stability against corrosion, and no brown discoloration
existed
on any of the steel surfaces. The top coating layer formed by the method is a
polymer lubricant layer and the bottom coating layer formed is a zinc
phosphate
conversion coating layer.
The lubricated workpiece was weighted. Then, the polymer lubricant coating
layer
was washed with xylene in order to detach it and subsequently with water. The
workpiece was then dried and weighted. The phosphate coating layer was washed
with an alkaline solution containing NaOH, triethyl amine and EDTA (PL 83 from
Chemetall GmbH) in order to detach it. Finally, the workpiece was rinsed with
water,
dried and weighted once again. The coating weights on different substrate
surfaces
are listed in Table 5. These data relate to the use of lubricant 11.
Table 5: Coating weights on different substrate surfaces (Si, S2 and S3) in
g/m2
Substrate Polymer lubricant Zinc-phosphate coating Total
[g/m2]
coating weight [g/m2] weight [g/m2)]
Si 2.7 8.0
10.7
S2 5.0 8.7
13.7
S3 2.9 8.1
11.0
Drawing-tests of the coated substrate S3 were carried out to prove the cold
forming
performance with different drawing-speeds (three parallel runs 1 and II and
III). The
results are displayed in Table 6. The drawing test of run I was with 30 m/Min
drawing-
speed and 20% cross-sectional area reduction in each step. Run II was
performed
with 60 m/Min drawing-speed and 20% cross-sectional area reduction in each
step.
These data also relate to the use of lubricant 11.
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Table 6: Test parameters of drawing-performance of coated substrates S3
Run 1 (30 m/Min) Run 11(60 m/Min)
1. Draw 0(11mm) to
0(9.8mm) 0(11mm) to 0(9.8mm)
2. Draw 0(9.8mm) to
0(8.8mm) 0(9.8mm) to 0(8.8mm)
3. Draw 0(8.8mm) to
0(7.8mm) 0(8.8mm) to 0(7.8mm)
Both parallel runs showed good drawing performance. The coating layer on
substrate
S3 showed very good lubricating properties. In addition, the coating layers
showed a
very good stability against corrosion. After drawing a homogenous coating
layer still
existed on the wire surface and the steel wire substrate S3 showed no
scratches or
other visible imperfections on its steel surface. The remaining polymer
lubricant
coating weight and zinc phosphate coating weight are listed in Table 7. The
polymer
lubricant coating has a good lubricating performance and is thus suitable for
metal
cold forming with high speed drawing.
Table 7: Remaining coating weights of coated substrate S3 after drawing
Polymer lubricant coating Zinc phosphate coating
Total [g/m2]
weight [g/m2] weight [g/m2]
Run I 1.0 3.9
4.9
Run 11 0.7 2.8
3.5
Coated substrate S2 was cold extruded. The cold extrusion was successful. No
scratches or other visible imperfection existed on the cold extruded
substrates.
zo The coatings have proven to have a high quality and to be very suitable for
cold
forming with high drawing speeds and for cold extrusion. The remaining coating
layers adhered still firmly on the metal surface of the substrates.
After the cold forming process, the remaining coating layer can be washed
using
alkaline cleaner, e.g. Gardocleane S 5171 with Gardobonde Additive H 7375 from
Chemetall GmbH, or with acidic cleaner, e.g. Gardobond Additive H 7132 with
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Gardobonde Additive H 7390 from Chemetall GmbH, without impairing any of the
desired properties.
3.2 Coated substrates obtained from the 1-step-process as outlined in item 2.2
(inventive) - use of lubricant /2
The resulting coating layer on each of the coated workpieces is homogenous,
thick
and adhered firmly on the treated surface of each workpiece. The coating
layers
showed a very good stability against corrosion, and no brown discoloration
existed
on any of the steel surfaces. The top coating layer formed by the method is a
polymer lubricant layer and the bottom coating layer formed is an oxalate
conversion
coating layer.
The coating weights on the different substrates were determined by the method
described hereinbefore in item 3.1 and are listed in Table 8. These data
relate to the
use of lubricant 12.
Table 8: Coating weights on different substrate surfaces (31, 32 and 33) in
g/m2
Substrate Polymer lubricant Oxalate coating weight
Total [g/m2]
coating weight [g/m2] [g/m2)]
Si 6.9 7.7
14.6
S3 6.3 7.8
14.1
S2 9.0 12.5
21.5
Drawing-tests of the coated substrate Si were carried out to prove the cold
forming
performance with different drawing-speeds (three parallel runs I and II and
III). The
results are displayed in Table 9. The drawing test of run I was with 30 m/Min
drawing-
speed and 20% cross-sectional area reduction in each step. Run II was
performed
with 60 m/Min drawing-speed and 20% cross-sectional area reduction in each
step.
Run III was performed with 40 m/Min drawing-speed and 35% cross-sectional area
reduction in each step. These data also relate to the use of lubricant 12.
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Table 9: Test parameters of drawing-performance of coated substrate S3
Run 1 (30 m/Min) Run 11(60 m/Min) Run III (40
m/Min)
1. Draw 0(11mm) to 0(9.8mm) 0(11mm) to 0(9.8mm) 0(11mm) to 0(8.5mm)
2. Draw 0(9.8mm) to 0(8.8mm) 0(9.8mm) to 0(8.8mm) 0(8.5mm) to 0(7.4mm)
3. Draw 0(8.8mm) to 0(7.8mm) 0(8.8mm) to 0(7.8mm) nd
4. Draw 0(7.8mm) to 0(6.7mm) 0(7.8mm) to 0(6.7mm) nd
nd = not determined
5 All three parallel runs showed good drawing performance. The coating
layer on steel
wire showed very good lubricating properties. After drawing a homogenous
coating
layer still existed on the wire surface and the steel wire showed no scratches
or other
visible imperfections on steel surface. The remaining coating weights after
having
performed the drawing test are listed in Table 10. After drawing, the total
remaining
10 coating weights are all still higher than 6 g/m2. The steel wires could
even still be
drawn to reduce the diameter. These data also relate to the use of lubricant
12.
Table 10: Remaining coating weights of coated substrate S3 after drawing
Polymer lubricant Oxalate coating
Total coating weight
coating weight [g/m2] weight [g/m2] [girnz]
Run 1 3.2 3.8 7.0
Run 11 3.4 5.2 8.6
Run III 2.7 3.6 6.3
Coated substrate S2 was cold extruded. The cold extrusion was successful. No
scratches or other visible imperfection existed on the cold extruded
substrates.
The coatings have proven to have a high quality and to be very suitable for
cold
zo forming with high drawing speeds and for cold extrusion. The remaining
coating
layers adhered still firmly on the metal surface of the substrates.
After the cold forming process, the remaining coating layer can be washed
using
alkaline cleaner, e.g. Gardocleane S 5171 with Gardobonde Additive H 7375 from
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Chemetall GmbH, or with acidic cleaner, e.g. Gardobonde Additive H 7132 with
Gardobonde Additive H 7390 from Chemetall GmbH, without impairing any of the
desired properties.
3.3 Coated substrates obtained from the 1-step-process as outlined in item 2.3
(inventive) - use of lubricant /3
The resulting coating layer on each of the coated workpieces is homogenous,
thin
and adhered firmly on the treated surface of each workpiece, which is
especially
suitable for tube industry. The coating layers showed a good stability against
corrosion, and no brown discoloration existed on any of the steel surfaces.
The top
coating layer formed by the method is a polymer lubricant layer and the bottom
coating layer formed is an iron phosphate coating layer.
The coating weights on the different substrates were determined by the method
described hereinbefore in item 3.1 and are listed in Table 11. These data
relate to the
use of lubricant 13.
Table 11: Coating weights on different substrate surfaces (S1 and S5) in g/m2
Substrate Polymer lubricant Iron phosphate coating Total
[g/m2]
coating weight [g/m2] weight [g/m2)]
Si 2.1 1.1 3.2
S5 2.1 0.9 3.0
3.4 Coated substrates obtained from the 1-step-process as outlined in item 2.4
(inventive) - use of lubricant 14
The resulting coating layer on each of the coated workpieces is homogenous,
thick
and adhered firmly on the treated surface of each workpiece. The coating
layers
showed a very good stability against corrosion, and no brown discoloration
existed
on any of the aluminum surfaces. The top coating layer formed by the method is
a
polymer lubricant layer and the bottom coating layer formed is a calcium
aluminate
conversion coating layer.
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The polymer coating weights on the different substrates were determined by the
method described hereinbefore in item 3.1. The calcium aluminate coating layer
was
washed with an acid solution containing 10% HNO3 in order to detach it.
Finally, the
workpiece was rinsed with water, dried and weighted once again.
The coating weights on aluminum slug (S6) are given in Table 12. These data
relate
to the use of lubricant 14.
Table 12: Coating weights on aluminum slug surfaces (S6) in g/m2
Substrate Polymer lubricant Calcium alum inate Total
[g/m2]
coating weight [g/m2] coating weight [g/m2)]
S6 8.2 5.3 13.5
3.5 Comparing coated substrates obtained from inventive 1-step process as
outlined
in item 2.1 with coated substrates obtained from a conventional multi-step
process as
outlined in item 2.5, which make use of conventional lubricant 15 for steel
treatment
The coating properties obtained from 1-step process as outlined in item 2.1
are
comparable or slightly better than coating obtained from conventional multi-
step
process at outlined in item 2.5. However, only one process step has to be
performed
zo in case of the inventive method and thus no rinsing step is necessary as
in case of
the comparative method and the total coating weights obtained in case of the
inventive 1-step method are higher than in case of the comparative multi-steps
method.
3.6 Comparing coated substrates obtained from inventive 1-step process as
outlined
in item 2.2 with coated substrates obtained from a conventional multi-step
process as
outlined in item 2.6, which make use of conventional lubricant 15 for steel
treatment
The coating properties obtained from 1-step process as outlined in item 2.2
are
comparable or slightly better than coating obtained from conventional multi-
step
process at outlined in item 2.6. However, only one process step has to be
performed
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in case of the inventive method and thus no rinsing step is necessary as in
case of
the comparative method and the total coating weights obtained in case of the
inventive 1-step method are higher than in case of the comparative multi-steps
method.
3.7 Coated substrates obtained from the 1-step-process as outlined in item 2.2
(inventive) - use of lubricant /6
Wherein the oxalate coating weights on substrates Si to S3 in case of using
lubricant
12 were found to be in a range of 7.7 to 12.5 g/m2 as it is evident from Table
8, the
observed oxalate coating weights in case of using lubricant 16 in the same
manner as
described in item 2.2 were unexpectedly found to be substantially lower,
namely in a
range of from only 4.0 to 6.0 g/m2. This effect is thus associated with the
use of
Fe(111) ions as accelerator in 12 vs. the use of nitroguanidine in 16, which
is
unexpected.
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