Title of Invention	CONDITIONING OF A LITHO STRIP
Abstract	The invention relates to a method of conditioning the surface of a work piece, particularly of a strip or sheet, more particularly of a lithostrip or lithosheet, consisting of an aluminium alloy. The object of the present invention to provide a method for conditioning the surface of a work piece and a work piece consisting of an aluminium alloy enabling an increasing manufacturing speed in electro-chemically graining and maintaining at the same time a high quality of the grained surface, is solved by a conditioning method which comprises at least the two steps degreasing the surface of the work piece with a degreasing medium and subsequently cleaning the surface of the work piece by pickling.

Title of Invention

CONDITIONING OF A LITHO STRIP

Abstract

The invention relates to a method of conditioning the surface of a work piece, particularly of a strip or sheet, more particularly of a lithostrip or lithosheet, consisting of an aluminium alloy. The object of the present invention to provide a method for conditioning the surface of a work piece and a work piece consisting of an aluminium alloy enabling an increasing manufacturing speed in electro-chemically graining and maintaining at the same time a high quality of the grained surface, is solved by a conditioning method which comprises at least the two steps degreasing the surface of the work piece with a degreasing medium and subsequently cleaning the surface of the work piece by pickling.

Full Text	WO 2006/122852 PCT/EP2006/061358 1 Conditioning of a litho strip The invention relates to a method of conditioning the surface of a work piece, particularly of a strip or sheet, more particularly of a lithostrip or lithosheet, consisting of an aluminium alloy. Work pieces such as strips or sheets consisting of an aluminium alloy are often surface treated after finishing rolling to prepare them for the next manufacturing step. In particular strips or sheet for lithographic printing are conditioned to achieve a predetermined surface roughness in a subsequent graining process. Lithostrips or sheets are usually degreased after finishing rolling. As known from the US-patent specification US 5,997,721, degreasing respectively cleaning of the surface is done in one step by anodising the aluminium alloy sheet with AC current in an acidic electrolyte bath. Another way to degrease or clean aluminium slivers is known from the German patent DE 43 17 815 Cl namely the use of an alkaline medium. However, prior electro-chemical graining of the lithostrips they are usually subjected to sodium hydroxide in a pre-treatment to degrease and clean the surface again. This step takes place in principle at the side of the manufacture of lithographic printing plates. Due to the increasing manufacturing speed during electro-chemical graining of the lithostrips time for pre-treatment of the surface of the lithostrips and for the electro-chemical WO 2006/122852 PCT/EP2006/061358 2 graining itself decreases. It has been found that due to the increasing manufacturing speed the pre-treatment with sodium hydroxide is not sufficient enough to remove all contaminants from the surface of the lithostrip. As a consequence, the results in electro-chemically graining are not stable and surface defects occur on electro- chemically grained lithostrips or sheets. However, a reduction of the manufacturing speed causes higher production costs for lithographic printing plates. Hence, it is an object of the invention to provide a method for conditioning the surface of a work piece and a work piece consisting of an aluminium alloy enabling an increasing manufacturing speed in electro-chemical graining and maintaining at the same time a high quality of the electro-chemical grained surface of the work piece. According to a first teaching of the present invention the above mentioned object is solved by a method of conditioning the surface of an aluminium work piece consisting of an aluminium alloy, which method comprises at least the two steps degreasing the surface of the work piece with a degreasing medium and subsequently cleaning the surface of the work piece by pickling. It has been surprisingly found that a combination of the inventive two step conditioning method with the usually effected pre-treatment with sodium hydroxide prior electro-chemical graining of the lithostrips leads to stable results in the electro-chemical graining even if manufacturing speeds are increased. The inventive conditioning method provides surfaces of an aluminium work piece which are almost free of subsurface oxide particles introduced by rolling without anodising the surface of the WO 2006/122852 PCT/EP2006/061358 3 aluminium work piece as known from the prior art. As a result, the surface of the aluminium alloy work piece conditioned with the inventive method is fully grained during electro-chemical graining at charge densities which arc distinctly lower than needed in electro-chemical graining after conventional cleaning, i.e. the charge density is less than 900 C/dm2. According to a first embodiment of the invention it is preferred to use an alkaline or an acid medium or an organic solvent as degreasing medium to degrease the surface of the work piece. An organic solvent such as isopropyl-alcohol degreases the surface of the aluminium work piece effectively whereas alkaline or acid degreasing media has the additional advantage that the surface of the aluminium work piece is sensitised for the following pickling step. According to a second embodiment of the inventive conditioning method a further improvement with respect to removal of rolling oil is achieved if the degreasing medium contains at least 1,5 to 3 % by weight of a composite of 5 - 40 % sodium tripolyphosphate, 3 - 10 % sodium gluconate, 30 - 70 % soda and 3 - 8 % of a composite of non-ionic and anionic surfactants. The described degreasing medium removes rolling oil and other contaminants from the surface of the conditioned aluminium work piece with a high effectiveness. Preferably, the degreasing effect of the degreasing medium can be enhanced if the temperature of the degreasing medium increases. Preferably, sodium hydroxide is utilised for pickling. Using sodium hydroxide in pickling leads to a good removal of oxide islands on the surface of the aluminium work WO 2006/122852 PCT/EP2006/061358 4 piece is achieved, in particular at elevated temperatures, i.e. equal or more than 7 0 °C. However, even at lower temperatures sodium hydroxide supports a stable electro- chemical graining process with increased manufacturing speed. Furthermore, hydrofluoric acid can be used as well for pickling. According to a further advantages embodiment of the inventive method pickling comprises AC-cleaning with phosphoric acid. During AC-cleaning an alternating current supports pickling process and phosphoric acid is used as electrolyte. Phosphoric acid attacks in particular the oxide islands on the surface of the aluminium work piece which are introduced during rolling. The aluminium of the surface of the lithostrip is not attacked very strongly. Using AC-cleaning with phosphoric acid after the degreasing step of the inventive method a good removal of oxide islands and contaminants from the surface of the aluminium work piece is achieved. However, AC-cleaning is also possible using as electrolyte sulphuric acid. More preferably, according to a further embodiment of the invention phosphoric acid is utilised for pickling. Phosphoric acid, even in absence of an AC current, has the advantage that it attacks mainly the oxide islands on the surface of the aluminium work piece and leads merely to a removal of small amount of the aluminium of the work piece itself. As a consequence pickling can be accomplished very thoroughly without removing to much aluminium from the surface of the work piece. Surprisingly, it has been found that the results achieved by pickling only with phosphoric acid are superior compared to the pickling with phosphoric acid supported by AC current. It is presumed that the absence of any oxide film, which is build during AC- WO 2006/122852 PCT/EP2006/061358 5 cleaning, is the reason for the superior results of phosphoric acid in combination with the degreasing step. Preferably, the work piece is a strip or a sheet, in particular a lithostrip or a lithosheet. In this case the necessary electro-chemical graining process for manufacturing lithostrips or lithosheets can be accomplished thoroughly within less time and the manufacturing speed can be increased. Furthermore, the charge density needed can be reduced while providing a fully grained strip or sheet surface. More preferably, the inventive conditioning method is accompli shed subsequent the manufacturing of a strip, in particular a lithostrip, and the conditioned strip is reeled on a coil. In this case a coil of a conditioned lithostrip can be provided comprising an optimum performance in further elcectro-chemical graining processes used to manufacture lithographic printing plates. According to a second teaching of the present invention the above mentioned object is solved by a work piece consisting of an aluminium alloy conditioned by the inventive method. As outlined before, the inventive work piece provides a cleaned surface with an optimum performance for a subsequent electro-chemical graining process. More preferably, the work piece is a strip or a sheet, in particular a lithostrip or a lithosheet. Lithostrip or sheets are produced for lithographic printing plates and differ from ,,,normal" sheets due to the aluminium alloy they consist of and their specific thickness, which is WO 2006/122852 PCT/EP2006/061358 6 typically less than 1 mm. Furthermore, the surface of lithostr.i.ps and sheets has to be prepared for a roughening process, since manufacturing of lithographic printing plates generally comprises an electro-chemical graining process to prepare the surface of the lithographic printing plates for the printing process. With the inventive sheets or strips, in particular with the inventive lithosheets or lithostrips, the necessary electro-chemical graining of the surface can be accomplished in shorter time with a reduced charge carrier density. Beside an optimised surface of the inventive work piece the mechanical features and an improved graining structure during electro-chemical graining can be provided if the aluminium alloy of the work piece is one of the aluminium alloys AA1050, AA1100, AA3103 or AlMg0,5. These aluminium alloys provide the mechanical strength needed for lithographic printing plates while enabling due to the low amount of alloying constituents a homogeneous graining of the surface. However, work pieces consisting of other aluminium alloys may provide the same advantages. According to a more preferably embodiment of the inventive work piece the aluminium alloy contains the following alloying constituents in percent by weight: Si 0,3 % ≤ Fe Cu Mn Mg Zn WO 2006/122852 PCT/EP2006/061358 7 Ti impurities each less than 0,005 % in sum max. 0,15 %,rest Al. The inventive aluminium alloy has state of the art mechanical and graining properties, in particular when the lithostrip consisting of said aluminium alloy is conditioned with the inventive method. The inventive method of conditioning the surface of an aluminium work piece as well as the inventive work piece can be designed and developed further in many different ways. In this respect, it is referred to the dependent claims of the independent claims 1 and 8 as well as to the description of embodiments of the present invention in connections with the drawings. The drawings shows in Fig. la) to 1c) pictures of a transmission electron microscope (SEM) of the surface of an aluminium alloy work piece conditioned with methods according to three different embodiments of the present invention. In the present embodiments of the inventions the work piece consist of a cold rolled AlMg0,5 aluminium alloy. However, it has been found that the results achieved with a AlMg0,5 aluminium alloy are representative for the other aluminium alloys mentioned in the claims, too. On the left side Fig. la) to lc) show SEM pictures of a degreased surface of the work piece, whereby degreasing has been accomplished by a medium containing at least 1,5 - 3 % by weight of a composite of 5 - 40 % sodium tripolyphosphate, 3 - 10 % sodium gluconate, 30 - 70 % soda and 3 - 8 % of a composite of non-ionic and anionic surfactants. The dark areas are identified as rolled-in subsurface oxide islands. These oxide islands are typically not removed WO 2006/122852 PCT/EP2006/061358 8 during degreasing. However, it has been found that the capability of the pre-treatments prior to the electro- chemical graining to remove subsurface oxide islands is very important to improve the results of electro-chemical graining, since the oxide islands prevent the respective surface area from being grained. In Fig. la) on the right side the work piece surface of the left picture of Fig. la) is shown after a treatment with sodium hydroxide with a concentration of 50 g/1 for 1.0 s and at a temperature of 80°C according to a first embodiment of the inventive conditioning method. On the one hand pickling with sodium hydroxide at the elevated temperature has removed almost completely the oxide island which indicates the interaction between the two conditioning steps of degreasing and pickling. On the other hand the pitted structure indicates that pickling already attacks the bulk material of the work piece surface. However, this pitted structure may be avoided by reducing the temperature or the time of pickling with sodium hydroxide. Fig. 1b) shows on the right a SEM picture of the surface of the Inventive work piece conditioned with an AC- cleaning in an phosphoric acid electrolyte. The AC- cleaning is accomplished in the present embodiment of the invention with a current density of 10 A/dm2 with a concentration of phosphoric acid of 20 % at a temperature of 80 °C for 10 s. Comparing left SEM picture after degreasing and the right SEM picture after degreasing and pickling with AC-cleaning in phosphoric acid it can be derived that small parts of the black coloured oxide island has been left on the work piece surface. However, a pitted structure which indicates that the bulk material WO 2006/122852 PCT/EP2006/061358 9 has been attacked, has not been observed with AC-cleaning in phosphoric acid in this embodiment of the present invention. Fig. 1c) presents the surface of the inventive aluminium work piece conditioned with phosphoric acid as second step. In comparison with the degreased work piece surface, pickling with phosphoric acid shows that the oxide islands are attacked mainly and removed from the work piece surface without leaving a pitted structure as shown after a conditioning with sodium hydroxide. The pickling with phosphoric acid shows the best results with respect to removing of subsurface, rolled-in oxide islands. The parameters regarding concentration, temperature and application time are variable and depend on each other. Hence, similar results may be achievable with different parameters. Anyhow, the inventive two-step method of conditioning the surface of aluminium work pieces provides almost complete removal of rolled-in subsurface oxide islands enabling a reduction of the charge entry during electro-chemical graining to achieved a fully grained surface. Since fully grained surfaces are particularly desired in manufacturing lithosheets and lithostrips an advantageous pre-treatment prior electro-chemical graining is presented with the inventive conditioning method. To investigate the ability of the inventive two-step conditioning of the aluminium work piece to be applied in a mass production further test with different concentrations, temperatures has been done. As a result, for phosphoric acid with concentrations from 20 % to 50%, at temperatures more or equal than 70 °C an application WO 2006/122852 PCT/EP2006/061358 10 time of 0,1s to 10s shows good results with respect to a removal of subsurface oxide islands on the aluminium workpiece. Hence, the inventive two step conditioning method of the surface of aluminium work pieces can be applied even in a mass production of conditioned aluminium work pieces. -11- Zl/cb 050 672WO 01. November 2 007 New Claims 1. Method of conditioning the surface of a lithostrip or a iithosheet consisting of an aluminium alloy, which method comprises at least the two steps - degreasing the surface of the lithostrip or the illhosheet. with a degreasing medium and subsequently - cleaning the surface of the lithostrip or the Iithosheet by pickling, wherein sodium hydroxide or phosphoric acid is utilised for pickling or pickling comprises AC- cleaning with phosphoric acid. 2. Method according to claim 1, wherein an alkaline or an acid medium or an organic solvent is used as degreasing medium. 3. Method according to claim 1 or 2, wherein the degreasing medium contains at least l,b to 3% by weight of a composite of 5 - 40% sodium tripolyphosphate, 3 - 10 % sodium gluconate, 30 - 70% soda and 3 - 8% of a composite of non-ionic and anionic surfactants. 4. Method according to claim 1 to 3, wherein the conditioning is accomplished subsequently to manufacturing of the strip and the conditioned strip is reeled on a coil. -12 - 5. Lithost:ri p or 1 i thosheet conditioned by a method accordinq to claim 1 to 4. 6. Lithostrip or lithosheet according to claim 5, wherein the aluminium alloy is one of the aluminium alloys AA 1050, AA 1100, AA 3103 or AlMg0,5. 7. Lithostrip or lithosheet according to claim 5 or 6, wherein the aluminium alloy contains the following alloying constituents in percent by weight: Si 0, 3 % ≤ Fe ≤ 0, 4 %, Cu Mn Mg Zn Ti impurities each less than 0,005% in sum max. 0,15 %, rest A1. The invention relates to a method of conditioning the surface of a work piece, particularly of a strip or sheet, more particularly of a lithostrip or lithosheet, consisting of an aluminium alloy. The object of the present invention to provide a method for conditioning the surface of a work piece and a work piece consisting of an aluminium alloy enabling an increasing manufacturing speed in electro-chemically graining and maintaining at the same time a high quality of the grained surface, is solved by a conditioning method which comprises at least the two steps degreasing the surface of the work piece with a degreasing medium and subsequently cleaning the surface of the work piece by pickling.

Full Text

WO 2006/122852 PCT/EP2006/061358
1
Conditioning of a litho strip
The invention relates to a method of conditioning the
surface of a work piece, particularly of a strip or sheet,
more particularly of a lithostrip or lithosheet,
consisting of an aluminium alloy.
Work pieces such as strips or sheets consisting of an
aluminium alloy are often surface treated after finishing
rolling to prepare them for the next manufacturing step.
In particular strips or sheet for lithographic printing
are conditioned to achieve a predetermined surface
roughness in a subsequent graining process. Lithostrips or
sheets are usually degreased after finishing rolling. As
known from the US-patent specification US 5,997,721,
degreasing respectively cleaning of the surface is done in
one step by anodising the aluminium alloy sheet with AC
current in an acidic electrolyte bath. Another way to
degrease or clean aluminium slivers is known from the
German patent DE 43 17 815 Cl namely the use of an
alkaline medium.
However, prior electro-chemical graining of the
lithostrips they are usually subjected to sodium hydroxide
in a pre-treatment to degrease and clean the surface
again. This step takes place in principle at the side of
the manufacture of lithographic printing plates. Due to
the increasing manufacturing speed during electro-chemical
graining of the lithostrips time for pre-treatment of the
surface of the lithostrips and for the electro-chemical

WO 2006/122852 PCT/EP2006/061358
2
graining itself decreases. It has been found that due to
the increasing manufacturing speed the pre-treatment with
sodium hydroxide is not sufficient enough to remove all
contaminants from the surface of the lithostrip. As a
consequence, the results in electro-chemically graining
are not stable and surface defects occur on electro-
chemically grained lithostrips or sheets. However, a
reduction of the manufacturing speed causes higher
production costs for lithographic printing plates.
Hence, it is an object of the invention to provide a
method for conditioning the surface of a work piece and a
work piece consisting of an aluminium alloy enabling an
increasing manufacturing speed in electro-chemical
graining and maintaining at the same time a high quality
of the electro-chemical grained surface of the work piece.
According to a first teaching of the present invention the
above mentioned object is solved by a method of
conditioning the surface of an aluminium work piece
consisting of an aluminium alloy, which method comprises
at least the two steps degreasing the surface of the work
piece with a degreasing medium and subsequently cleaning
the surface of the work piece by pickling.
It has been surprisingly found that a combination of the
inventive two step conditioning method with the usually
effected pre-treatment with sodium hydroxide prior
electro-chemical graining of the lithostrips leads to
stable results in the electro-chemical graining even if
manufacturing speeds are increased. The inventive
conditioning method provides surfaces of an aluminium work
piece which are almost free of subsurface oxide particles
introduced by rolling without anodising the surface of the

WO 2006/122852 PCT/EP2006/061358
3
aluminium work piece as known from the prior art. As a
result, the surface of the aluminium alloy work piece
conditioned with the inventive method is fully grained
during electro-chemical graining at charge densities which
arc distinctly lower than needed in electro-chemical
graining after conventional cleaning, i.e. the charge
density is less than 900 C/dm2.
According to a first embodiment of the invention it is
preferred to use an alkaline or an acid medium or an
organic solvent as degreasing medium to degrease the
surface of the work piece. An organic solvent such as
isopropyl-alcohol degreases the surface of the aluminium
work piece effectively whereas alkaline or acid degreasing
media has the additional advantage that the surface of the
aluminium work piece is sensitised for the following
pickling step.
According to a second embodiment of the inventive
conditioning method a further improvement with respect to
removal of rolling oil is achieved if the degreasing
medium contains at least 1,5 to 3 % by weight of a
composite of 5 - 40 % sodium tripolyphosphate,
3 - 10 % sodium gluconate, 30 - 70 % soda and 3 - 8 % of a
composite of non-ionic and anionic surfactants. The
described degreasing medium removes rolling oil and other
contaminants from the surface of the conditioned aluminium
work piece with a high effectiveness. Preferably, the
degreasing effect of the degreasing medium can be enhanced
if the temperature of the degreasing medium increases.
Preferably, sodium hydroxide is utilised for pickling.
Using sodium hydroxide in pickling leads to a good removal
of oxide islands on the surface of the aluminium work

WO 2006/122852 PCT/EP2006/061358
4
piece is achieved, in particular at elevated temperatures,
i.e. equal or more than 7 0 °C. However, even at lower
temperatures sodium hydroxide supports a stable electro-
chemical graining process with increased manufacturing
speed. Furthermore, hydrofluoric acid can be used as well
for pickling.
According to a further advantages embodiment of the
inventive method pickling comprises AC-cleaning with
phosphoric acid. During AC-cleaning an alternating current
supports pickling process and phosphoric acid is used as
electrolyte. Phosphoric acid attacks in particular the
oxide islands on the surface of the aluminium work piece
which are introduced during rolling. The aluminium of the
surface of the lithostrip is not attacked very strongly.
Using AC-cleaning with phosphoric acid after the
degreasing step of the inventive method a good removal of
oxide islands and contaminants from the surface of the
aluminium work piece is achieved. However, AC-cleaning is
also possible using as electrolyte sulphuric acid.
More preferably, according to a further embodiment of the
invention phosphoric acid is utilised for pickling.
Phosphoric acid, even in absence of an AC current, has the
advantage that it attacks mainly the oxide islands on the
surface of the aluminium work piece and leads merely to a
removal of small amount of the aluminium of the work piece
itself. As a consequence pickling can be accomplished very
thoroughly without removing to much aluminium from the
surface of the work piece. Surprisingly, it has been found
that the results achieved by pickling only with phosphoric
acid are superior compared to the pickling with phosphoric
acid supported by AC current. It is presumed that the
absence of any oxide film, which is build during AC-

WO 2006/122852 PCT/EP2006/061358
5
cleaning, is the reason for the superior results of
phosphoric acid in combination with the degreasing step.
Preferably, the work piece is a strip or a sheet, in
particular a lithostrip or a lithosheet. In this case the
necessary electro-chemical graining process for
manufacturing lithostrips or lithosheets can be
accomplished thoroughly within less time and the
manufacturing speed can be increased. Furthermore, the
charge density needed can be reduced while providing a
fully grained strip or sheet surface.
More preferably, the inventive conditioning method is
accompli shed subsequent the manufacturing of a strip, in
particular a lithostrip, and the conditioned strip is
reeled on a coil. In this case a coil of a conditioned
lithostrip can be provided comprising an optimum
performance in further elcectro-chemical graining
processes used to manufacture lithographic printing
plates.
According to a second teaching of the present invention
the above mentioned object is solved by a work piece
consisting of an aluminium alloy conditioned by the
inventive method. As outlined before, the inventive work
piece provides a cleaned surface with an optimum
performance for a subsequent electro-chemical graining
process.
More preferably, the work piece is a strip or a sheet, in
particular a lithostrip or a lithosheet. Lithostrip or
sheets are produced for lithographic printing plates and
differ from ,,,normal" sheets due to the aluminium alloy
they consist of and their specific thickness, which is

WO 2006/122852 PCT/EP2006/061358
6
typically less than 1 mm. Furthermore, the surface of
lithostr.i.ps and sheets has to be prepared for a roughening
process, since manufacturing of lithographic printing
plates generally comprises an electro-chemical graining
process to prepare the surface of the lithographic
printing plates for the printing process. With the
inventive sheets or strips, in particular with the
inventive lithosheets or lithostrips, the necessary
electro-chemical graining of the surface can be
accomplished in shorter time with a reduced charge carrier
density.
Beside an optimised surface of the inventive work piece
the mechanical features and an improved graining structure
during electro-chemical graining can be provided if the
aluminium alloy of the work piece is one of the aluminium
alloys AA1050, AA1100, AA3103 or AlMg0,5. These aluminium
alloys provide the mechanical strength needed for
lithographic printing plates while enabling due to the low
amount of alloying constituents a homogeneous graining of
the surface. However, work pieces consisting of other
aluminium alloys may provide the same advantages.
According to a more preferably embodiment of the inventive
work piece the aluminium alloy contains the following
alloying constituents in percent by weight:
Si 0,3 % ≤ Fe Cu Mn Mg Zn
WO 2006/122852 PCT/EP2006/061358
7
Ti impurities each less than 0,005 % in sum max.
0,15 %,rest Al.
The inventive aluminium alloy has state of the art
mechanical and graining properties, in particular when the
lithostrip consisting of said aluminium alloy is
conditioned with the inventive method.
The inventive method of conditioning the surface of an
aluminium work piece as well as the inventive work piece
can be designed and developed further in many different
ways. In this respect, it is referred to the dependent
claims of the independent claims 1 and 8 as well as to the
description of embodiments of the present invention in
connections with the drawings. The drawings shows in Fig.
la) to 1c) pictures of a transmission electron microscope
(SEM) of the surface of an aluminium alloy work piece
conditioned with methods according to three different
embodiments of the present invention.
In the present embodiments of the inventions the work
piece consist of a cold rolled AlMg0,5 aluminium alloy.
However, it has been found that the results achieved with
a AlMg0,5 aluminium alloy are representative for the other
aluminium alloys mentioned in the claims, too. On the left
side Fig. la) to lc) show SEM pictures of a degreased
surface of the work piece, whereby degreasing has been
accomplished by a medium containing at least 1,5 - 3 % by
weight of a composite of 5 - 40 % sodium tripolyphosphate,
3 - 10 % sodium gluconate, 30 - 70 % soda and 3 - 8 % of a
composite of non-ionic and anionic surfactants. The dark
areas are identified as rolled-in subsurface oxide
islands. These oxide islands are typically not removed

WO 2006/122852 PCT/EP2006/061358
8
during degreasing. However, it has been found that the
capability of the pre-treatments prior to the electro-
chemical graining to remove subsurface oxide islands is
very important to improve the results of electro-chemical
graining, since the oxide islands prevent the respective
surface area from being grained. In Fig. la) on the right
side the work piece surface of the left picture of Fig.
la) is shown after a treatment with sodium hydroxide with
a concentration of 50 g/1 for 1.0 s and at a temperature of
80°C according to a first embodiment of the inventive
conditioning method.
On the one hand pickling with sodium hydroxide at the
elevated temperature has removed almost completely the
oxide island which indicates the interaction between the
two conditioning steps of degreasing and pickling. On the
other hand the pitted structure indicates that pickling
already attacks the bulk material of the work piece
surface. However, this pitted structure may be avoided by
reducing the temperature or the time of pickling with
sodium hydroxide.
Fig. 1b) shows on the right a SEM picture of the surface
of the Inventive work piece conditioned with an AC-
cleaning in an phosphoric acid electrolyte. The AC-
cleaning is accomplished in the present embodiment of the
invention with a current density of 10 A/dm2 with a
concentration of phosphoric acid of 20 % at a temperature
of 80 °C for 10 s. Comparing left SEM picture after
degreasing and the right SEM picture after degreasing and
pickling with AC-cleaning in phosphoric acid it can be
derived that small parts of the black coloured oxide
island has been left on the work piece surface. However, a
pitted structure which indicates that the bulk material

WO 2006/122852 PCT/EP2006/061358
9
has been attacked, has not been observed with AC-cleaning
in phosphoric acid in this embodiment of the present
invention.
Fig. 1c) presents the surface of the inventive aluminium
work piece conditioned with phosphoric acid as second
step. In comparison with the degreased work piece surface,
pickling with phosphoric acid shows that the oxide islands
are attacked mainly and removed from the work piece
surface without leaving a pitted structure as shown after
a conditioning with sodium hydroxide. The pickling with
phosphoric acid shows the best results with respect to
removing of subsurface, rolled-in oxide islands. The
parameters regarding concentration, temperature and
application time are variable and depend on each other.
Hence, similar results may be achievable with different
parameters.
Anyhow, the inventive two-step method of conditioning the
surface of aluminium work pieces provides almost complete
removal of rolled-in subsurface oxide islands enabling a
reduction of the charge entry during electro-chemical
graining to achieved a fully grained surface. Since fully
grained surfaces are particularly desired in manufacturing
lithosheets and lithostrips an advantageous pre-treatment
prior electro-chemical graining is presented with the
inventive conditioning method.
To investigate the ability of the inventive two-step
conditioning of the aluminium work piece to be applied in
a mass production further test with different
concentrations, temperatures has been done. As a result,
for phosphoric acid with concentrations from 20 % to 50%,
at temperatures more or equal than 70 °C an application

WO 2006/122852 PCT/EP2006/061358
10
time of 0,1s to 10s shows good results with respect to a
removal of subsurface oxide islands on the aluminium
workpiece. Hence, the inventive two step conditioning
method of the surface of aluminium work pieces can be
applied even in a mass production of conditioned aluminium
work pieces.

-11-
Zl/cb 050 672WO
01. November 2 007
New Claims
1. Method of conditioning the surface of a lithostrip or
a iithosheet consisting of an aluminium alloy, which
method comprises at least the two steps
- degreasing the surface of the lithostrip or the
illhosheet. with a degreasing medium and subsequently
- cleaning the surface of the lithostrip or the
Iithosheet by pickling,
wherein sodium hydroxide or phosphoric acid is
utilised for pickling or pickling comprises AC-
cleaning with phosphoric acid.
2. Method according to claim 1, wherein
an alkaline or an acid medium or an organic solvent is
used as degreasing medium.
3. Method according to claim 1 or 2, wherein
the degreasing medium contains at least l,b to 3% by
weight of a composite of 5 - 40% sodium
tripolyphosphate, 3 - 10 % sodium gluconate, 30 - 70%
soda and 3 - 8% of a composite of non-ionic and
anionic surfactants.
4. Method according to claim 1 to 3, wherein the
conditioning is accomplished subsequently to
manufacturing of the strip and the conditioned strip
is reeled on a coil.

-12 -
5. Lithost:ri p or 1 i thosheet conditioned by a method
accordinq to claim 1 to 4.
6. Lithostrip or lithosheet according to claim 5, wherein
the aluminium alloy is one of the aluminium alloys AA
1050, AA 1100, AA 3103 or AlMg0,5.
7. Lithostrip or lithosheet according to claim 5 or 6,
wherein the aluminium alloy contains the following
alloying constituents in percent by weight:
Si 0, 3 % ≤ Fe ≤ 0, 4 %,
Cu Mn Mg Zn Ti impurities each less than 0,005% in sum max. 0,15 %,
rest A1.

The invention relates to a method of conditioning the
surface of a work piece, particularly of a strip or sheet,
more particularly of a lithostrip or lithosheet,
consisting of an aluminium alloy. The object of the
present invention to provide a method for conditioning the
surface of a work piece and a work piece consisting of an
aluminium alloy enabling an increasing manufacturing speed
in electro-chemically graining and maintaining at the same
time a high quality of the grained surface, is solved by a
conditioning method which comprises at least the two steps
degreasing the surface of the work piece with a degreasing
medium and subsequently cleaning the surface of the work
piece by pickling.

Documents:

04434-kolnp-2007-abstract.pdf

04434-kolnp-2007-claims.pdf

04434-kolnp-2007-correspondence others.pdf

04434-kolnp-2007-description complete.pdf

04434-kolnp-2007-drawings.pdf

04434-kolnp-2007-form 1.pdf

04434-kolnp-2007-form 2.pdf

04434-kolnp-2007-form 3.pdf

04434-kolnp-2007-form 5.pdf

04434-kolnp-2007-international exm report.pdf

04434-kolnp-2007-international publication.pdf

04434-kolnp-2007-international search report.pdf

04434-kolnp-2007-pct request form.pdf

04434-kolnp-2007-priority document.pdf

4434-KOLNP-2007-(17-07-2012)-CORRESPONDENCE.pdf

4434-KOLNP-2007-(17-07-2012)-PCT SEARCH REPORT.pdf

4434-KOLNP-2007-(28-03-2013)-PETITION UNDER RULE 137.pdf

4434-KOLNP-2007-(29-01-2013)-ABSTRACT.pdf

4434-KOLNP-2007-(29-01-2013)-AMANDED PAGES OF SPECIFICATION.pdf

4434-KOLNP-2007-(29-01-2013)-ANNEXURE TO FORM 3.pdf

4434-KOLNP-2007-(29-01-2013)-CLAIMS.pdf

4434-KOLNP-2007-(29-01-2013)-CORRESPONDENCE.pdf

4434-KOLNP-2007-(29-01-2013)-DESCRIPTION (COMPLETE).pdf

4434-KOLNP-2007-(29-01-2013)-DRAWINGS.pdf

4434-KOLNP-2007-(29-01-2013)-FORM-1.pdf

4434-KOLNP-2007-(29-01-2013)-FORM-2.pdf

4434-KOLNP-2007-(29-01-2013)-OTHERS.pdf

4434-KOLNP-2007-(29-01-2013)-PA.pdf

4434-KOLNP-2007-CORRESPONDENCE.pdf

4434-KOLNP-2007-EXAMINATION REPORT.pdf

4434-KOLNP-2007-FORM 18-1.1.pdf

4434-kolnp-2007-form 18.pdf

4434-KOLNP-2007-FORM 26.pdf

4434-KOLNP-2007-GRANTED-ABSTRACT.pdf

4434-KOLNP-2007-GRANTED-CLAIMS.pdf

4434-KOLNP-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

4434-KOLNP-2007-GRANTED-DRAWINGS.pdf

4434-KOLNP-2007-GRANTED-FORM 1.pdf

4434-KOLNP-2007-GRANTED-FORM 2.pdf

4434-KOLNP-2007-GRANTED-FORM 3.pdf

4434-KOLNP-2007-GRANTED-FORM 5.pdf

4434-KOLNP-2007-GRANTED-SPECIFICATION-COMPLETE.pdf

4434-KOLNP-2007-INTERNATIONAL PUBLICATION.pdf

4434-KOLNP-2007-INTERNATIONAL SEARCH REPORT & OTHERS.pdf

4434-KOLNP-2007-OTHERS.pdf

4434-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf

abstract-04434-kolnp-2007.jpg

« Previous Patent

Next Patent »

Patent Number

258785

Indian Patent Application Number

4434/KOLNP/2007

PG Journal Number

07/2014

Publication Date

14-Feb-2014

Grant Date

06-Feb-2014

Date of Filing

19-Nov-2007

Name of Patentee

HYDRO ALUMINIUM DEUTSCHLAND GMBH

Applicant Address

ETTORE-BUGATTI-STR. 6-14 51149 COLOGNE, GERMANY

Inventors:

#	Inventor's Name	Inventor's Address
1	BERNHARD KERNIG	HONINGER WEG 145 50969 COLOGNE, GERMANY
2	HENK JAN BRINKMAN	AM KREUTER 7, 53177 BONN,GERMANY

PCT International Classification Number

C23G 1/12

PCT International Application Number

PCT/EP2006/061358

PCT International Filing date

2006-04-05

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	05010847.1	2005-05-19	EUROPEAN UNION