EP0889147A1 - Tin plating method and bath having wide optimum current density range - Google Patents
Tin plating method and bath having wide optimum current density range Download PDFInfo
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- EP0889147A1 EP0889147A1 EP97905428A EP97905428A EP0889147A1 EP 0889147 A1 EP0889147 A1 EP 0889147A1 EP 97905428 A EP97905428 A EP 97905428A EP 97905428 A EP97905428 A EP 97905428A EP 0889147 A1 EP0889147 A1 EP 0889147A1
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- Prior art keywords
- tin
- plating
- ions
- plating bath
- current density
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/30—Electroplating: Baths therefor from solutions of tin
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
- C25D7/06—Wires; Strips; Foils
- C25D7/0614—Strips or foils
Definitions
- the present invention provides a tin-plating bath and a method for tin-plating capable of plating a steel sheet with tin at a high current density to produce mainly a tin-plated steel sheet (a so-called tinplate) and having a wide optimum current density range.
- Tinplate was invented during the period from the latter half of the 13th century to the half of the 16th century, and was produced principally by hot dipping.
- a process capable of continuously electroplating a steel sheet with tin was completed.
- a steel sheet in a coil is continuously degreased, pickled, electroplated with tin, and subjected to melting treatment, chemical treatment and oil coating.
- Degreasing is conducted usually by exposure to an alkaline solution, electrolysis and mechanical treatment using a brush to remove cold rolling oil, etc. from the steel sheet.
- Pickling is carried out by immersion or electrolysis of the steel sheet in an aqueous solution of sulfuric acid, etc. to reduce and remove oxides formed thereon.
- Tin-plating is conducted by electroplating in a plating bath containing Sn ions. Melting treatment is performed for the purpose of ensuring brightness and corrosion resistance of the plated steel sheet. The treatment is conducted by induction heating or electric heating to heat the tin coating to temperature above the melting point of tin and immediately quenching the tin in warmed water. Chemical treatment is conducted for the purpose of preventing oxidation of the tin coating. In the treatment, the tin-plated steel sheet is subjected to immersion or electrolysis to form a chromate film thereon. Oil coating is carried out for the purpose of imparting scratch resistance and rust preventive properties to the tin-plated steel sheet.
- the steel sheet is coated with oil such as ATBC (acetyl tributyl citrate) or DOS (dioctyl sebacate). Moreover, in some applications, the steel sheet may not be subjected to hot dip coating and chemical treatment.
- the continuous treatments as mentioned above are usually conducted by passing the steel sheet in coil having a weight of several tens of ton at a line speed of 300 to 400 m/min, they may be conducted by passing the sheet at a line speed of 100 m/min owing to operating conditions such as the connection of a new coil.
- a phenolsulfonic acid bath and a halogen bath have been used in the industry as plating baths for tin-plating (e.g., The Technology of Tinplate, London Edward Arnold Ltd., p213 (1965)), and the phenolsufonic acid bath is employed in about 80% of tinplate production lines in the world.
- the use of a methanesulfonic acid bath (Metal Finishing, January, AESF, p17 (1990)) has been examined in recent years to protect the environment, and the bath has been put into practical use in some of lines in the world.
- a steel sheet is electroplated with tin while the steel sheet is being used as a cathode.
- the current density of tin-plating varies depending on the variation of the tinplate production line speed (high current density at the time of a high line speed, low current density at the time of a low line speed)
- the variation width must be within the optimum current density range determined by the quality of the tinplate to be produced.
- the quality of the tinplate herein designates K-plate conditions (see ASTM A632, for example, an ATC current (alloy tin couple current) up to 0.12 ⁇ A/cm 2 , an ISV (iron solution value) up to 6.9 mg/51 ml and a TC (tin crystal) # up to 9, appearance being included sometimes depending on the application). Moreover, when the plating current density is too low, a so-called "low current phenomenon" in which plating defects are formed to impair the appearance and corrosion resistance takes place.
- the present inventors have, therefore, intensively investigated the relationship between a tin-plating current density and a plating quality, and an optimum current density range while changing the concentrations of Sn ions, Fe ions and organic additives in a tin-plating bath, the relative speed between a plating solution and a steel sheet to be plated, etc. As a result, they have discovered that the combined effect of an increase in the tin concentration and the solution flow speed not only improves the threshold current density but also widens the optimum current density range.
- Electrodeposition nucleus generation becomes predominant and the tin plating becomes denser as the current density increases.
- hydrogen is be generated, and the plating becomes powdery at such a current density, to cause a problem with regard to the adhesion.
- the phenomenon seems to depend on a current density, it actually depends on a potential. That is, a low current density results when the potential is low, and a high current density results when the potential is high. Accordingly, it is considered that there exists an optimum potential range as there exists an optimum current density range.
- the potential or optimum potential range of a steel sheet during plating is considered to be influenced by the electric capacitance of an electric double layer at the interface of the steel sheet to be plated and the plating solution.
- the electric capacitance of an electrical double layer is strongly influenced by the thickness of the electric double layer and the ionic strength, it is significantly changed by the combined effect of a decrease in the boundary layer thickness caused by an increase in the flow speed of the plating solution, and an increase in the ionic strength caused by an increase in the concentration of Sn ions.
- the dependence of the current density on the potential is greatly changed, and the current density is greatly changed by a potential change smaller than before.
- the optimum current density range is, therefore, widened.
- the present invention is based on the discovery as mentioned above, and provides what is described below.
- a tinplate product of high quality is to be produced efficiently in a high speed tin-plating line (e.g., at a line speed of 700 m/min)
- prior tinning technology requires from 10 to 20 plating cells.
- the production can be performed with fewer plating cells (several), and therefore an extremely high economic efficiency can be achieved.
- the Sn ion concentration in a tin-plating bath not only improves the threshold current density but also plays a role in widening the optimum current density range by the combined effects achieved by the Sn ion concentration and the high flow rate. Accordingly, when the Sn concentration in a plating bath is too low, the combined effects cannot be achieved sufficiently. Accordingly, the Sn concentration in the plating bath must be at least 40 g/l. The effects of improving the threshold current density and widening the range of the optimum current density are enhanced as the Sn ion concentration increases. However, since Sn at high cost dissipates owing to dragging out and splashing when the Sn ion concentration exceeds 100 g/l, the concentration becomes industrially disadvantageous. Accordingly, the Sn ion concentration in the plating bath in the present invention is desirably up to 100 g/l, and it must be from 40 to 100 g/l.
- the tin-plating bath used in the present invention contains a base acid, such as phenolsulfonic acid, methanesulfonic acid and alkanolsulfonic acid, which are used in conventional tin-plating baths.
- a base acid such as phenolsulfonic acid, methanesulfonic acid and alkanolsulfonic acid
- the base acid plays a role in improving the electric conductivity or making the electrodeposition form dense in addition to a role in stabilizing the Sn ions in the plating bath.
- concentration of the base acid When the concentration of the base acid is too low, stabilized Sn ions cannot exist and ordinary tin-plating becomes difficult owing to a decrease in the electric conductivity and so on.
- the concentration of the base acid must, therefore, be at least 20 g/l.
- the base acid concentration must, therefore, be up to 400 g/l. Accordingly, the base acid concentration in the tin-plating bath must be from 20 to 400 g/l.
- the base acids used in the present invention may be obtained from industrial products produced by general industrial production processes. Moreover, it does not matter even when the industrial products contain unavoidable impurities such as unreacted products and colored oxides mixed in the products during synthesis of the base acids.
- phenolsulfonic acid produced as an industrial product by a general industrial production process such as the cumene process may be used. It does not matter even when the industrially produced phenolsulfonic acid contains unavoidable impurities such as unreacted phenol and colored oxides mixed therein during synthesis thereof.
- a tin-plating bath containing further a brightener such as ethoxylated ⁇ -naphtholsulfonic acid (ENSA) or ethoxylated ⁇ -naphthol (EN) may be used for obtaining a tin-plated steel sheet having a gloss appearance when the tin-plated steel sheet is used in a field where the appearance is required.
- ENSA ethoxylated ⁇ -naphtholsulfonic acid
- EN ethoxylated ⁇ -naphthol
- the steel sheet In order to exhibit a gloss appearance imparted by the brightener, the steel sheet must be plated in a tin-plating bath containing at least 0.1 g/l of ethoxylated ⁇ -naphtholsulfonic acid and/or at least 0.1 g/l of ethoxylated ⁇ -naphthol.
- the brightener adheres to the tin-plated steel sheet and cannot be removed even in the step of washing the plating solution after plating when the addition amount exceeds 10 g/l, and a defective quality such as a poor appearance is caused.
- the addition amount of the brightener must, therefore, be up to 10 g/l. Accordingly, brighteners such as ⁇ -naphtholsulfonic acid and ethoxylated ⁇ -naphthol are each added in an amount of 0.1 to 10 g/l.
- ⁇ -naphtholsulfonic acid and ethoxylated ⁇ -naphthol produced as general industrial chemicals may be used as the brighteners in the present invention, and the effect of the present invention is not lost even when these compounds contain unavoidable impurities therein from the synthesis thereof.
- a tin-plated steel sheet obtained by the use of a tin-plating bath which contains Fe ions and having a trace amount of Fe in the tin plating layer is used.
- Such a tin-plated steel sheet is used because when the tin-plated steel sheet develops a defect reaching the base steel, the corrosion current at the defective portion is mainly produced by a potential difference between the tin plating layer and the base steel.
- the potential difference is decreased, and the corrosion current can be lowered.
- the tin-plating bath In order to produce such a tin-plated steel sheet having a corrosion resistance, the tin-plating bath must contain at least 0.1 g/l of Fe ions. When the concentration of the Fe ions therein is increased, the amount of Fe in the tin plating layer tends to increase, and the effect of improving the corrosion resistance is also enhanced. However, when the Fe concentration in the plating bath exceeds 15 g/l, oxidation of Sn ions with Fe ions becomes excessive. The plating bath must, therefore, contain up to 15 g/l of Fe ions. Accordingly, the concentration of Fe ions in the plating bath must be defined to be from 0.1 to 15 g/l.
- the tin-plating bath of the present invention has been described above.
- the flow of the metal bath is indispensable.
- the speed of the steel sheet to be plated herein designates a transfer speed of the steel sheet in a so-called continuous plating line
- the moving speed of the plating solution herein designates a generally measured average bulk moving speed.
- the relative speed difference between the steel sheet to be plated and the plating solution must be at least 2 m/sec.
- the relative speed difference between the steel sheet to be plated and the plating solution is preferably at least 4 m/sec.
- the steel sheet may be passed through a stationary plating bath at a speed higher than a predetermined value e.g., 2 m/sec or more, or the plating solution may be forcibly moved in the same direction as or in a direction opposite to the transfer direction of the steel sheet.
- a predetermined value e.g. 2 m/sec or more
- the effect of improving the threshold current density and that of widening the optimum current density range are enhanced as the relative speed difference therebetween increases.
- the relative speed difference therebetween exceeds 20 m/sec, there arise problems of fluttering of the steel sheet and a nonuniform flow of the plating solution in the width direction.
- the high relative speed difference is economically disadvantageous because the energy (mainly an electrical energy for driving pumps, motors, etc.) consumed for generating the relative speed difference becomes excessively high. Accordingly, the relative speed difference therebetween must be from 2 to 20 m/sec.
- the bath temperature during plating is desirably from 30 to 60°C.
- the bath temperature is desirably at least 30°C.
- the viscosity of the plating bath lowers and the separation of the tinning solution is improved as the bath temperature is raised.
- the bath temperature is desirably held at up to 60°C.
- the tin-plating bath according to the present invention is prepared by a procedure as described below. Water to a volume of about half the final desired volume of the tin-plating bath is charged in vessel equipped with a stirring apparatus. A base acid such as phenolsulfonic acid in a predetermined amount is subsequently charged into the vessel, and the contents are stirred. A predetermined amount of Sn ions are subsequently dissolved by adding tin oxide or by electrochemically dissolving metallic tin. Furthermore, a brightener such as ethoxylated ⁇ -naphtholsulfonic acid or ethoxylated ⁇ -naphthol and Fe ions are added if necessary. A predetermined amount of Fe ions can be dissolved by adding iron oxide or by electrochemically dissolving metallic Fe.
- the tin-plating bath is introduced in a vertical or horizontal tin-plating tank used in a conventional continuous steel sheet plating line, and the relative speed difference between a steel sheet to be plated and the plating bath is set to 2 to 20 m/sec.
- the speed difference is adjusted by controlling the traveling speed of the steel sheet.
- the relative speed difference therebetween may be set to 2 to 20 m/sec by controlling the traveling speed of the steel sheet and the flow speed of the plating solution while the plating solution is forcibly flown in the direction opposite to or with the traveling direction thereof.
- the tinplate production line is operated with the variation width of the current density within the optimum current density range being at least 80 A/dm 2 , preferably at least 250 A/dm 2 .
- the tinplate production line may also be operated, if necessary, with the variation width thereof being at least 350 A/dm 2 , particularly at least 450 A/dm 2 .
- a continuous tinplate production line can be in practice operated at a high speed, only when the optimum current density range is wide and the line is actually operated with such a wide variation width of the current density within the wide optimum current density range. It has heretofore been unknown that such a line operation is possible, and such a line operation has not been conducted. In conventional industrial tinplate production lines, only an optimum current density of about 5 to 30 A/dm 2 (variation width: up to 25 A/dm 2 ) has been adopted.
- an actually high tinplate production line speed is realized by a combination of a high tin ion concentration, a high relative speed difference between a steel sheet to be plated and a plating solution, a wide variation width of a current density within a wide optimum current density range and, if necessary, a specific base acid at a high concentration.
- the tinplate production line is also operated at a low speed in accordance with connection of a new coil or the like procedure, by widely varying the current density within the optimum current density range.
- the tinplate production line may thus be continuously operated.
- a uniform flow rate of the plating solution must be maintained in the width and longitudinal directions.
- the plating solution may be satisfactorily made to flow by a conventional water-jet pump.
- the amount of tin plating is adjusted by the amount of a current.
- the steel sheet thus plated is washed with water, and sent to the next steps such as reflowing and chemical treatments.
- Tin-plating baths were prepared by the procedures as mentioned above, and steel sheets 0.22 mm thick for tinplate were plated with tin and the optimum current density range was measured. Measurements of the optimum current density range were made on corrosion-resistant tinplates and matte tinplates.
- Samples of corrosion-resistant tinplates were prepared by plating steel sheets with 11.2 g/m 2 of Sn at various current densities, and subjected to melting treatment by electrical heating at a rate of 30°C/sec.
- the K-plate adaptability test was conducted by measuring an ATC current (alloy tin couple current), an ISV (iron solution value), the TC (tin crystal), described in ASTM A632, and judging whether or not the tin-plated steel sheets are adapted to K-plate.
- ATC current alloy tin couple current
- ISV iron solution value
- TC tin crystal
- the gloss appearance test was conducted by visually evaluating the appearance of the samples, and it was judged whether or not the samples had a particularly excellent brightness.
- the corrosion resistance test was conducted by immersing the samples in 5% citric acid at 30°C for a month, and evaluating the corrosion resistance by visually judging the corrosion of the steel sheets.
- the optimum current density range is defined as a current density range where samples satisfying the K-plate conditions in the K-plate adaptability test can be produced.
- a current density range where samples having a particularly excellent gloss can be produced is defined as a gloss optimum current density range
- a current density range where samples having a particularly excellent corrosion resistance can be produced is defined as a high corrosion resistance optimum current density range.
- samples of matte tinplates were prepared by plating steel sheets with 2.8 g/m 2 of Sn at various current densities.
- the gloss test was conducted by visually evaluating the appearance of the samples, and judged whether or not the samples had a particularly excellent gloss.
- the corrosion resistance test was conducted by immersing the samples in 5% citric acid at 30°C for a month, and evaluating the corrosion resistance by visually judging the corrosion of the steel sheets.
- a current density range where samples having an excellent gloss can be produced is defined as a gloss optimum current density range and a current density range where samples having an excellent corrosion resistance can be produced is defined as a high corrosion resistance optimum current density range.
- Table 1 shows the results of examples.
- phenolsulfonic acid was used as the base acid in Examples 1 to 36, and also in Comparative Examples 1 to 4.
- Methanesulfonic acid was used as the base acid in Examples 37 and 38.
- ⁇ -Alkanolsulfonic acid was used as the base acid in Example 39.
- ENSN and EN in the table represent ethoxylated ⁇ -alkanolsulfonic acid and ethoxylated ⁇ -alkanol, respectively.
- the prior art requires from 10 to 20 plating cells.
- the production can be performed with fewer plating cells (few or several), and therefore an economically extremely high efficiency can be achieved.
- the present invention is useful for mass-producing tin-plated steel sheets (tinplate products).
- tinplate products examples and Comparative Examples of phenolsulfonic acid bath Tin-plating bath composition (g/l) Bath temp. Plating solution flow rate Corrosion-resistant tinplate (A/dm 2 ) Sn ions
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Abstract
A steel sheet is plated with tin in a tin-plating
bath containing 40 to 100 g/l of Sn ions, preferably
containing further 20 to 400 g/l of phenolsulfonic acid,
the relative speed difference between the steel sheet to
be plated and the plating solution being set at 2 to 20
m/sec to give a tinplate product, the plating being
operated at a wide optimum current density range of at
least 80 A/dm2, or at an even wider optimum current
density range of at least 250 A/dm2.
Description
The present invention provides a tin-plating bath
and a method for tin-plating capable of plating a steel
sheet with tin at a high current density to produce
mainly a tin-plated steel sheet (a so-called tinplate)
and having a wide optimum current density range.
Tinplate was invented during the period from the
latter half of the 13th century to the half of the 16th
century, and was produced principally by hot dipping.
At the beginning of the 20th century, a process capable
of continuously electroplating a steel sheet with tin
was completed. In the process, a steel sheet in a coil
is continuously degreased, pickled, electroplated with
tin, and subjected to melting treatment, chemical
treatment and oil coating. Degreasing is conducted
usually by exposure to an alkaline solution,
electrolysis and mechanical treatment using a brush to
remove cold rolling oil, etc. from the steel sheet.
Pickling is carried out by immersion or electrolysis of
the steel sheet in an aqueous solution of sulfuric acid,
etc. to reduce and remove oxides formed thereon. Tin-plating
is conducted by electroplating in a plating bath
containing Sn ions. Melting treatment is performed for
the purpose of ensuring brightness and corrosion
resistance of the plated steel sheet. The treatment is
conducted by induction heating or electric heating to
heat the tin coating to temperature above the melting
point of tin and immediately quenching the tin in warmed
water. Chemical treatment is conducted for the purpose
of preventing oxidation of the tin coating. In the
treatment, the tin-plated steel sheet is subjected to
immersion or electrolysis to form a chromate film
thereon. Oil coating is carried out for the purpose of
imparting scratch resistance and rust preventive
properties to the tin-plated steel sheet. The steel
sheet is coated with oil such as ATBC (acetyl tributyl
citrate) or DOS (dioctyl sebacate). Moreover, in some
applications, the steel sheet may not be subjected to
hot dip coating and chemical treatment. Although the
continuous treatments as mentioned above are usually
conducted by passing the steel sheet in coil having a
weight of several tens of ton at a line speed of 300 to
400 m/min, they may be conducted by passing the sheet at
a line speed of 100 m/min owing to operating conditions
such as the connection of a new coil.
The step of tin-plating which is the most important
step among the tinplate production steps described above
will be explained below in detail.
A phenolsulfonic acid bath and a halogen bath have
been used in the industry as plating baths for tin-plating
(e.g., The Technology of Tinplate, London Edward
Arnold Ltd., p213 (1965)), and the phenolsufonic acid
bath is employed in about 80% of tinplate production
lines in the world. The use of a methanesulfonic acid
bath (Metal Finishing, January, AESF, p17 (1990)) has
been examined in recent years to protect the
environment, and the bath has been put into practical
use in some of lines in the world.
Using such plating baths, a steel sheet is
electroplated with tin while the steel sheet is being
used as a cathode. Although the current density of tin-plating
varies depending on the variation of the
tinplate production line speed (high current density at
the time of a high line speed, low current density at
the time of a low line speed), the variation width must
be within the optimum current density range determined
by the quality of the tinplate to be produced. The
quality of the tinplate herein designates K-plate
conditions (see ASTM A632, for example, an ATC current
(alloy tin couple current) up to 0.12 µA/cm2, an ISV
(iron solution value) up to 6.9 mg/51 ml and a TC (tin
crystal) # up to 9, appearance being included sometimes
depending on the application). Moreover, when the
plating current density is too low, a so-called "low
current phenomenon" in which plating defects are formed
to impair the appearance and corrosion resistance takes
place. Moreover, when the current density is too high,
the current efficiency quickly decreases, and so-called
"burnt plating" in which tin plating becomes powdery and
plating defects are formed to impair the appearance and
the corrosion resistance of the tin-plated steel sheet
takes place. Accordingly tin-plating must be conducted
in the optimum current density range in which the low
current phenomenon and burnt plating do not take place,
that is, plating defects are not formed substantially.
In conventionally industrialized tinplate production
lines, the lower limit of the optimum current density
range is from 5 to 10 A/ dm2, and the upper limit
thereof is from 20 to 30 A/dm2.
As described above, there is a close relationship
between the line speed and the current density range of
tin-plating. For example, for the purpose of improving
the productivity of tinplates, it is satisfactory to
increase the line speed. However, a tin-plating method
is not satisfactory when tin-plating can be carried out
only at a high current density. The tin-plating method
cannot be applied to industrial use unless a tinplate of
high quality can be produced by the method even at a low
current density which is within the optimum current
density range in the method because the method cannot
correspond to the acceleration or deceleration of the
tinplate line at the time of connecting a new coil.
The cost competition between the tinplate products
and other products such as aluminum, bottles and paper
containers has become fierce in recent years. For the
purpose of economically producing products of high
quality, it has become necessary to improve the
productivity by operating the tinplate line at high
speed and to maintain the product quality. When
conventional techniques are applied to the high speed
operation of the tinplate production line, longer tin-plating
tanks must be installed in accordance with a
decrease in the plating time due to the high speed
operation. Since the installation requires an enormous
amount of investment, high speed operation by the
conventional techniques is not suited to an industrial
tinplate production line.
On the other hand, it has been generally known that
increasing the current in tin-plating can be achieved by
increasing the amount of material transfer in the
boundary layer near the steel sheet to be plated, namely
by increasing the concentration of Sn ions or the flow
speed of the plating solution. However, the optimum
current density range mentioned above is not widened
substantially by the procedure described above. As a
result, the conventional techniques cannot correspond to
the acceleration and deceleration of the tinplate
production line at the time of connecting a new coil,
and cannot be suited to the line.
For example, plating baths and plating methods in
which sulfuric acid as a principal component of the
baths are used at a high current density are disclosed
in Japanese Unexamined Patent Publication (Kokai) No. 6-346272
("Sulfuric acid bath for tin-plating at a high
current density and a tin-plating method"), Japanese
Unexamined Patent Publication (Kokai) No. 7-207489 ("Tin
plating bath"), and Japanese Unexamined Patent
Publication (Kokai) No. 8-260183 ("Sulfuric acid bath
having a high electric conductivity, a good sludge
inhibiting ability and tin-dissolution function").
However, these patent publications provide only methods
by which plating can be conducted at an increased tin
ion concentration and a high plating current density.
However, the techniques in the publications do not widen
the optimum current density range.
Accordingly, there is a strong desire for a tin-plating
bath and a tin-plating method with which tin-plating
can be conducted at a high current density and
in a wide optimum current density range so that the
acceleration and deceleration of the plating line speed
ranging from a high speed to a low speed at which a new
coil is connected can be performed.
The present inventors have, therefore, intensively
investigated the relationship between a tin-plating
current density and a plating quality, and an optimum
current density range while changing the concentrations
of Sn ions, Fe ions and organic additives in a tin-plating
bath, the relative speed between a plating
solution and a steel sheet to be plated, etc. As a
result, they have discovered that the combined effect of
an increase in the tin concentration and the solution
flow speed not only improves the threshold current
density but also widens the optimum current density
range.
The mechanism of this discovery is considered to be
as described below. In general, when the current
density is low, electrodeposition nucleus growth takes
place predominantly in electrodepsition in plating.
Electrodeposition nucleus generation becomes predominant
and the tin plating becomes denser as the current
density increases. When the current density is
increased further, hydrogen is be generated, and the
plating becomes powdery at such a current density, to
cause a problem with regard to the adhesion. Although
the phenomenon seems to depend on a current density, it
actually depends on a potential. That is, a low current
density results when the potential is low, and a high
current density results when the potential is high.
Accordingly, it is considered that there exists an
optimum potential range as there exists an optimum
current density range. On the other hand, the potential
or optimum potential range of a steel sheet during
plating is considered to be influenced by the electric
capacitance of an electric double layer at the interface
of the steel sheet to be plated and the plating
solution. Although the electric capacitance of an
electrical double layer is strongly influenced by the
thickness of the electric double layer and the ionic
strength, it is significantly changed by the combined
effect of a decrease in the boundary layer thickness
caused by an increase in the flow speed of the plating
solution, and an increase in the ionic strength caused
by an increase in the concentration of Sn ions. As a
result, the dependence of the current density on the
potential is greatly changed, and the current density is
greatly changed by a potential change smaller than
before. The optimum current density range is,
therefore, widened.
The present invention is based on the discovery as
mentioned above, and provides what is described below.
Accordingly, when a tinplate product of high
quality is to be produced efficiently in a high speed
tin-plating line (e.g., at a line speed of 700 m/min),
prior tinning technology requires from 10 to 20 plating
cells. However, according to the present invention, the
production can be performed with fewer plating cells
(several), and therefore an extremely high economic
efficiency can be achieved.
The mode of operation of the present invention will
be explained below in detail.
In the present invention, the Sn ion concentration
in a tin-plating bath not only improves the threshold
current density but also plays a role in widening the
optimum current density range by the combined effects
achieved by the Sn ion concentration and the high flow
rate. Accordingly, when the Sn concentration in a
plating bath is too low, the combined effects cannot be
achieved sufficiently. Accordingly, the Sn
concentration in the plating bath must be at least 40
g/l. The effects of improving the threshold current
density and widening the range of the optimum current
density are enhanced as the Sn ion concentration
increases. However, since Sn at high cost dissipates
owing to dragging out and splashing when the Sn ion
concentration exceeds 100 g/l, the concentration becomes
industrially disadvantageous. Accordingly, the Sn ion
concentration in the plating bath in the present
invention is desirably up to 100 g/l, and it must be
from 40 to 100 g/l.
The tin-plating bath used in the present invention
contains a base acid, such as phenolsulfonic acid,
methanesulfonic acid and alkanolsulfonic acid, which are
used in conventional tin-plating baths.
The base acid plays a role in improving the
electric conductivity or making the electrodeposition
form dense in addition to a role in stabilizing the Sn
ions in the plating bath. When the concentration of the
base acid is too low, stabilized Sn ions cannot exist
and ordinary tin-plating becomes difficult owing to a
decrease in the electric conductivity and so on. The
concentration of the base acid must, therefore, be at
least 20 g/l. Although the effects of stabilizing Sn
ions and improving the electric conductivity are
enhanced as the base acid concentration increases, the
effects begin to saturate when the Sn concentration
exceeds 400 g/l, and the concentration is economically
disadvantageous. The base acid concentration must,
therefore, be up to 400 g/l. Accordingly, the base acid
concentration in the tin-plating bath must be from 20 to
400 g/l.
The base acids used in the present invention may be
obtained from industrial products produced by general
industrial production processes. Moreover, it does not
matter even when the industrial products contain
unavoidable impurities such as unreacted products and
colored oxides mixed in the products during synthesis of
the base acids. For example, phenolsulfonic acid
produced as an industrial product by a general
industrial production process such as the cumene process
may be used. It does not matter even when the
industrially produced phenolsulfonic acid contains
unavoidable impurities such as unreacted phenol and
colored oxides mixed therein during synthesis thereof.
Although it is possible to conduct the industrial
production using a tin-plating bath containing base acid
ions and Sn ions, a tin-plating bath containing further
a brightener such as ethoxylated α-naphtholsulfonic acid
(ENSA) or ethoxylated α-naphthol (EN) may be used for
obtaining a tin-plated steel sheet having a gloss
appearance when the tin-plated steel sheet is used in a
field where the appearance is required. In order to
exhibit a gloss appearance imparted by the brightener,
the steel sheet must be plated in a tin-plating bath
containing at least 0.1 g/l of ethoxylated α-naphtholsulfonic
acid and/or at least 0.1 g/l of
ethoxylated α-naphthol. Although the effect of
improving the gloss is enhanced in accordance with the
addition amount of each brightener, the brightener
adheres to the tin-plated steel sheet and cannot be
removed even in the step of washing the plating solution
after plating when the addition amount exceeds 10 g/l,
and a defective quality such as a poor appearance is
caused. The addition amount of the brightener must,
therefore, be up to 10 g/l. Accordingly, brighteners
such as α-naphtholsulfonic acid and ethoxylated α-naphthol
are each added in an amount of 0.1 to 10 g/l.
Furthermore, for example, α-naphtholsulfonic acid
and ethoxylated α-naphthol produced as general
industrial chemicals may be used as the brighteners in
the present invention, and the effect of the present
invention is not lost even when these compounds contain
unavoidable impurities therein from the synthesis
thereof.
Furthermore, for use in a field requiring more
excellent corrosion resistance, a tin-plated steel sheet
obtained by the use of a tin-plating bath which contains
Fe ions and having a trace amount of Fe in the tin
plating layer is used. Such a tin-plated steel sheet is
used because when the tin-plated steel sheet develops a
defect reaching the base steel, the corrosion current at
the defective portion is mainly produced by a potential
difference between the tin plating layer and the base
steel. However, when a trace amount of Fe exists in the
tin plating layer, the potential difference is
decreased, and the corrosion current can be lowered. In
order to produce such a tin-plated steel sheet having a
corrosion resistance, the tin-plating bath must contain
at least 0.1 g/l of Fe ions. When the concentration of
the Fe ions therein is increased, the amount of Fe in
the tin plating layer tends to increase, and the effect
of improving the corrosion resistance is also enhanced.
However, when the Fe concentration in the plating bath
exceeds 15 g/l, oxidation of Sn ions with Fe ions
becomes excessive. The plating bath must, therefore,
contain up to 15 g/l of Fe ions. Accordingly, the
concentration of Fe ions in the plating bath must be
defined to be from 0.1 to 15 g/l.
The tin-plating bath of the present invention has
been described above. In order to conduct tin-plating
at a high threshold current density and in a wide
optimum current density range, the flow of the metal
bath is indispensable. As described above, since the
flow of the plating solution has the effect of
decreasing the boundary layer thickness, it may be said
that the flow depends on a relative speed difference
between the steel sheet to be plated and that of the
plating solution. The speed of the steel sheet to be
plated herein designates a transfer speed of the steel
sheet in a so-called continuous plating line, and the
moving speed of the plating solution herein designates a
generally measured average bulk moving speed. When the
relative speed difference therebetween is too small, the
effect of decreasing the boundary layer thickness is not
sufficient, and conducting tin-plating at a high
threshold current density and in a wide optimum current
density range becomes difficult. Accordingly, the
relative speed difference between the steel sheet to be
plated and the plating solution must be at least 2
m/sec. Moreover, according to the discovery of the
present inventors, in order to promote removal of
bubbles which are included between the electrode and the
steel sheet and which impair the quality stability of
the tinplate products and bubbles generated during
plating, the relative speed difference between the steel
sheet to be plated and the plating solution is
preferably at least 4 m/sec.
In order to set the relative speed difference
between the steel sheet to be plated and the plating
solution to more than a predetermined value, for
example, the steel sheet may be passed through a
stationary plating bath at a speed higher than a
predetermined value e.g., 2 m/sec or more, or the
plating solution may be forcibly moved in the same
direction as or in a direction opposite to the transfer
direction of the steel sheet. The effect of improving
the threshold current density and that of widening the
optimum current density range are enhanced as the
relative speed difference therebetween increases.
However, when the relative speed difference therebetween
exceeds 20 m/sec, there arise problems of fluttering of
the steel sheet and a nonuniform flow of the plating
solution in the width direction. In addition to the
problems mentioned above, the high relative speed
difference is economically disadvantageous because the
energy (mainly an electrical energy for driving pumps,
motors, etc.) consumed for generating the relative speed
difference becomes excessively high. Accordingly, the
relative speed difference therebetween must be from 2 to
20 m/sec.
Furthermore, the bath temperature during plating is
desirably from 30 to 60°C. When the bath temperature is
low, the bath has a high viscosity, and the plating
solution on the tin-plated steel sheet cannot be
satisfactorily separated. Accordingly, the bath
temperature is desirably at least 30°C. The viscosity
of the plating bath lowers and the separation of the
tinning solution is improved as the bath temperature is
raised. However, when the bath temperature becomes
higher than 60°C, fumes are drastically generated to
pollute the operating environment, and holding the bath
concentration constant becomes difficult. Accordingly,
the bath temperature is desirably held at up to 60°C.
The tin-plating bath according to the present
invention is prepared by a procedure as described below.
Water to a volume of about half the final desired volume
of the tin-plating bath is charged in vessel equipped
with a stirring apparatus. A base acid such as
phenolsulfonic acid in a predetermined amount is
subsequently charged into the vessel, and the contents
are stirred. A predetermined amount of Sn ions are
subsequently dissolved by adding tin oxide or by
electrochemically dissolving metallic tin. Furthermore,
a brightener such as ethoxylated α-naphtholsulfonic acid
or ethoxylated α-naphthol and Fe ions are added if
necessary. A predetermined amount of Fe ions can be
dissolved by adding iron oxide or by electrochemically
dissolving metallic Fe.
The tin-plating bath is introduced in a vertical or
horizontal tin-plating tank used in a conventional
continuous steel sheet plating line, and the relative
speed difference between a steel sheet to be plated and
the plating bath is set to 2 to 20 m/sec. When the
plating bath is a stationary one where the plating
solution is not flowing substantially, the speed
difference is adjusted by controlling the traveling
speed of the steel sheet. Alternately, the relative
speed difference therebetween may be set to 2 to 20
m/sec by controlling the traveling speed of the steel
sheet and the flow speed of the plating solution while
the plating solution is forcibly flown in the direction
opposite to or with the traveling direction thereof.
As described above, in order to operate the
tinplate production line at high speed, it is necessary
that the line be operated at a high current density
corresponding to the high speed of the line and that the
line can be operated at a low current density when the
line speed is slowed down for connecting a new coil, or
the like procedure. Moreover, these current densities
must be within the optimum current density range.
According to the present invention, the tinplate
production line is operated with the variation width of
the current density within the optimum current density
range being at least 80 A/dm2, preferably at least 250
A/dm2. Furthermore, the tinplate production line may
also be operated, if necessary, with the variation width
thereof being at least 350 A/dm2, particularly at least
450 A/dm2. A continuous tinplate production line can be
in practice operated at a high speed, only when the
optimum current density range is wide and the line is
actually operated with such a wide variation width of
the current density within the wide optimum current
density range. It has heretofore been unknown that such
a line operation is possible, and such a line operation
has not been conducted. In conventional industrial
tinplate production lines, only an optimum current
density of about 5 to 30 A/dm2 (variation width: up to
25 A/dm2) has been adopted.
According to the present invention, an actually
high tinplate production line speed is realized by a
combination of a high tin ion concentration, a high
relative speed difference between a steel sheet to be
plated and a plating solution, a wide variation width of
a current density within a wide optimum current density
range and, if necessary, a specific base acid at a high
concentration. The tinplate production line is also
operated at a low speed in accordance with connection of
a new coil or the like procedure, by widely varying the
current density within the optimum current density
range. The tinplate production line may thus be
continuously operated.
In order to ensure a stabilized product quality in
conducting tin-plating by the method of the present
invention, a uniform flow rate of the plating solution
must be maintained in the width and longitudinal
directions. In order to realize the uniform flow rate,
it is important that the spacing between the anode and
the steel sheet be always held constant, and it is
desirable that an insoluble anode be used as the anode.
The plating solution may be satisfactorily made to flow
by a conventional water-jet pump.
The amount of tin plating is adjusted by the amount
of a current. The steel sheet thus plated is washed
with water, and sent to the next steps such as reflowing
and chemical treatments.
Tin-plating baths were prepared by the procedures
as mentioned above, and steel sheets 0.22 mm thick for
tinplate were plated with tin and the optimum current
density range was measured. Measurements of the optimum
current density range were made on corrosion-resistant
tinplates and matte tinplates.
Samples of corrosion-resistant tinplates were
prepared by plating steel sheets with 11.2 g/m2 of Sn at
various current densities, and subjected to melting
treatment by electrical heating at a rate of 30°C/sec.
These samples were subjected to a K-plate
adaptability test, a gloss appearance test and a
corrosion resistance test.
The K-plate adaptability test was conducted by
measuring an ATC current (alloy tin couple current), an
ISV (iron solution value), the TC (tin crystal),
described in ASTM A632, and judging whether or not the
tin-plated steel sheets are adapted to K-plate.
The gloss appearance test was conducted by visually
evaluating the appearance of the samples, and it was
judged whether or not the samples had a particularly
excellent brightness.
The corrosion resistance test was conducted by
immersing the samples in 5% citric acid at 30°C for a
month, and evaluating the corrosion resistance by
visually judging the corrosion of the steel sheets.
The optimum current density range is defined as a
current density range where samples satisfying the K-plate
conditions in the K-plate adaptability test can be
produced. In addition, a current density range where
samples having a particularly excellent gloss can be
produced is defined as a gloss optimum current density
range, and a current density range where samples having
a particularly excellent corrosion resistance can be
produced is defined as a high corrosion resistance
optimum current density range.
On the other hand, samples of matte tinplates were
prepared by plating steel sheets with 2.8 g/m2 of Sn at
various current densities.
These samples were subjected to a plate adhesion
test, a gloss appearance test and a corrosion resistance
test.
In the plate adhesion test, an adhesive tape was
applied to a plated steel sheet, and peeled off the
steel sheet. The plate adhesion was evaluated by
visually judging the amount of Sn adhering to the tape.
The gloss test was conducted by visually evaluating
the appearance of the samples, and judged whether or not
the samples had a particularly excellent gloss.
The corrosion resistance test was conducted by
immersing the samples in 5% citric acid at 30°C for a
month, and evaluating the corrosion resistance by
visually judging the corrosion of the steel sheets.
A current density range where samples having an
excellent gloss can be produced is defined as a gloss
optimum current density range and a current density
range where samples having an excellent corrosion
resistance can be produced is defined as a high
corrosion resistance optimum current density range.
Table 1 shows the results of examples. In the
table, phenolsulfonic acid was used as the base acid in
Examples 1 to 36, and also in Comparative Examples 1 to
4. Methanesulfonic acid was used as the base acid in
Examples 37 and 38. β-Alkanolsulfonic acid was used as
the base acid in Example 39. In addition, ENSN and EN
in the table represent ethoxylated α-alkanolsulfonic
acid and ethoxylated α-alkanol, respectively.
As shown in Tables 1 and 2, although the various
types optimum current density ranges were only about 20
A/dm2 in prior art as shown in Comparative Examples, the
various types of optimum current density ranges in the
present invention were as wide as from 1 A/dm2 to 300 to
500 A/dm2. Moreover, the current density range tended
to be widened as the Sn concentration in a tin-plating
bath increased, and as the relative speed difference
between the steel sheet to be plated and the plating
solution increased.
Accordingly, when a tinplate product of high
quality is to be produced efficiently in a high speed
tin-plating line (e.g., at a line speed of 700 m/min),
the prior art requires from 10 to 20 plating cells.
However, according to the present invention, the
production can be performed with fewer plating cells
(few or several), and therefore an economically
extremely high efficiency can be achieved.
The present invention is useful for mass-producing
tin-plated steel sheets (tinplate products).
Examples and Comparative Examples of phenolsulfonic acid bath | ||||||||||
Tin-plating bath composition (g/l) | Bath temp. | Plating solution flow rate | Corrosion-resistant tinplate (A/dm2) | |||||||
Sn ions | Base acid | ENSA | EN | Fe ions | (°C) | (m/sec) | O.C.D .R. | G.O.C .D.R. | H.C.R .O.C. D.R. | |
Ex. 1 | 42 | 138 | 0.00 | 0.00 | 0.00 | 50 | 5.5 | 1-300 | non | non |
Ex. 2 | 80 | 389 | 0.00 | 0.00 | 0.00 | 45 | 2.2 | 1-300 | non | non |
Ex. 3 | 65 | 22 | 0.00 | 0.00 | 0.01 | 30 | 15.7 | 1-400 | non | non |
Ex. 4 | 97 | 85 | 0.00 | 0.01 | 0.00 | 35 | 18.9 | 1-500 | non | non |
Ex. 5 | 55 | 289 | 0.00 | 0.00 | 0.07 | 60 | 8.7 | 1-300 | non | non |
Ex. 6 | 41 | 128 | 0.13 | 0.00 | 0.00 | 35 | 5.0 | 1-300 | 1-300 | non |
Ex. 7 | 78 | 391 | 5.46 | 0.00 | 0.00 | 32 | 3.5 | 1-300 | 1-300 | non |
Ex. 8 | 55 | 24 | 9.80 | 0.02 | 0.00 | 41 | 9.0 | 1-400 | 1-400 | non |
Ex. 9 | 97 | 106 | 2.54 | 0.00 | 0.03 | 54 | 15.7 | 1-500 | 1-500 | non |
Ex.10 | 51 | 256 | 3.00 | 0.00 | 0.00 | 45 | 2.1 | 1-300 | 1-300 | non |
Ex.11 | 45 | 80 | 0.00 | 9.94 | 0.08 | 41 | 12.9 | 1-300 | 1-300 | non |
Ex.12 | 65 | 356 | 0.00 | 5.42 | 0.00 | 58 | 14.0 | 1-400 | 1-400 | non |
Ex.13 | 78 | 321 | 0.00 | 0.16 | 0.01 | 60 | 6.0 | 1-400 | 1-400 | non |
Ex.14 | 42 | 264 | 0.00 | 2.25 | 0.00 | 55 | 8.6 | 1-300 | 1-300 | non |
Ex.15 | 52 | 180 | 3.40 | 0.40 | 0.00 | 58 | 4.0 | 1-300 | 1-300 | non |
Ex.16 | 63 | 76 | 2.80 | 5.90 | 0.02 | 47 | 2.3 | 1-300 | 1-300 | non |
Ex.17 | 68 | 195 | 8.70 | 6.00 | 0.00 | 51 | 18.9 | 1-500 | 1-500 | non |
Ex.18 | 42 | 138 | 0.00 | 0.10 | 8.40 | 50 | 5.5 | 1-300 | non | 1-300 |
Ex.19 | 80 | 389 | 0.03 | 0.00 | 12.60 | 45 | 2.2 | 1-300 | non | 1-300 |
Ex.20 | 65 | 22 | 0.00 | 0.04 | 6.00 | 30 | 15.7 | 1-500 | non | 1-500 |
Examples and Comparative Examples of phenolsulfonic acid bath | ||||||||||
Tin-plating bath composition (g/l) | Bath temp. | Plating solution flow rate | Matte tinplate (A/dm2) | |||||||
Sn ions | Base acid | ENSA | EN | Fe ions | (°C) | (m/sec) | O.C.D .R. | G.O.C .D.R. | H.C.R .O.C. D.R. | |
Ex. 1 | 42 | 138 | 0.00 | 0.00 | 0.00 | 50 | 5.5 | 1-300 | non | non |
Ex. 2 | 80 | 389 | 0.00 | 0.00 | 0.00 | 45 | 2.2 | 1-300 | non | non |
Ex. 3 | 65 | 22 | 0.00 | 0.00 | 0.01 | 30 | 15.7 | 1-400 | non | non |
Ex. 4 | 97 | 85 | 0.00 | 0.01 | 0.00 | 35 | 18.9 | 1-500 | non | non |
Ex. 5 | 55 | 289 | 0.00 | 0.00 | 0.07 | 60 | 8.7 | 1-300 | non | non |
Ex. 6 | 41 | 128 | 0.13 | 0.00 | 0.00 | 35 | 5.0 | 1-300 | 1-300 | non |
Ex. 7 | 78 | 391 | 5.46 | 0.00 | 0.00 | 32 | 3.5 | 1-300 | 1-300 | non |
Ex. 8 | 55 | 24 | 9.80 | 0.02 | 0.00 | 41 | 9.0 | 1-400 | 1-400 | non |
Ex. 9 | 97 | 106 | 2.54 | 0.00 | 0.03 | 54 | 15.7 | 1-500 | 1-500 | non |
Ex.10 | 51 | 256 | 3.00 | 0.00 | 0.00 | 45 | 2.1 | 1-300 | 1-300 | non |
Ex.11 | 45 | 80 | 0.00 | 9.94 | 0.08 | 41 | 12.9 | 1-300 | 1-300 | non |
Ex.12 | 65 | 356 | 0.00 | 5.42 | 0.00 | 58 | 14.0 | 1-400 | 1-400 | non |
Ex.13 | 78 | 321 | 0.00 | 0.16 | 0.01 | 60 | 6.0 | 1-400 | 1-400 | non |
Ex.14 | 42 | 264 | 0.00 | 2.25 | 0.00 | 55 | 8.6 | 1-300 | 1-300 | non |
Ex.15 | 52 | 180 | 3.40 | 0.40 | 0.00 | 58 | 4.0 | 1-300 | 1-300 | non |
Ex.16 | 63 | 76 | 2.80 | 5.90 | 0.02 | 47 | 2.3 | 1-300 | 1-300 | non |
Ex.17 | 68 | 195 | 8.70 | 6.00 | 0.00 | 51 | 18.9 | 1-500 | 1-500 | non |
Ex.18 | 42 | 138 | 0.00 | 0.10 | 8.40 | 50 | 5.5 | 1-300 | non | 1-300 |
Ex.19 | 80 | 389 | 0.03 | 0.00 | 12.60 | 45 | 2.2 | 1-300 | non | 1-300 |
Ex.20 | 65 | 22 | 0.00 | 0.04 | 6.00 | 30 | 15.7 | 1-500 | non | 1-500 |
Examples and Comparative Examples of phenolsulfonic acid bath | ||||||||||
Tin-plating bath composition (g/l) | Bath temp. | Plating solution flow rate | Corrosion-resistant tinplate (A/dm2) | |||||||
Sn ions | Base acid | ENSA | EN | Fe ions | (°C) | (m/sec) | O.C.D .R. | G.O.C .D.R. | H.C.R .O.C. D.R. | |
Ex.21 | 97 | 85 | 0.07 | 0.07 | 0.40 | 35 | 18.9 | 1-550 | non | 1-550 |
Ex.22 | 55 | 289 | 0.00 | 0.00 | 0.13 | 60 | 8.7 | 1-400 | non | 1-400 |
Ex.23 | 41 | 128 | 0.13 | 0.00 | 3.45 | 35 | 5.0 | 1-300 | 1-300 | 1-300 |
Ex.24 | 78 | 391 | 5.46 | 0.00 | 7.54 | 32 | 3.5 | 1-300 | 1-300 | 1-300 |
Ex.25 | 55 | 24 | 9.80 | 0.08 | 6.12 | 41 | 9.0 | 1-400 | 1-400 | 1-400 |
Ex.26 | 97 | 106 | 2.54 | 0.00 | 0.86 | 54 | 15.7 | 1-500 | 1-500 | 1-500 |
Ex.27 | 51 | 256 | 3.00 | 0.00 | 14.70 | 45 | 2.1 | 1-300 | 1-300 | 1-300 |
Ex.28 | 45 | 80 | 0.00 | 9.94 | 11.40 | 41 | 12.9 | 1-300 | 1-300 | 1-300 |
Ex.29 | 65 | 356 | 0.07 | 5.42 | 8.59 | 58 | 14.0 | 1-500 | 1-500 | 1-500 |
Ex.30 | 78 | 321 | 0.00 | 0.16 | 2.45 | 60 | 6.0 | 1-400 | 1-400 | 1-400 |
Ex.31 | 42 | 264 | 0.00 | 2.25 | 7.26 | 55 | 8.6 | 1-300 | 1-300 | 1-300 |
Ex.32 | 52 | 180 | 3.40 | 0.40 | 0.47 | 58 | 4.0 | 1-300 | 1-300 | 1-300 |
Ex.33 | 63 | 76 | 2.80 | 5.90 | 3.00 | 47 | 2.3 | 1-300 | 1-300 | 1-300 |
Ex.34 | 68 | 195 | 8.70 | 6.00 | 7.00 | 51 | 18.9 | 1-500 | 1-500 | 1-500 |
Ex.35 | 68 | 195 | 8.70 | 6.00 | 7.00 | 51 | 1.8 | 10-150 | 10-150 | 10-150 |
Ex.36 | 49 | 84 | 2.65 | 2.87 | 3.26 | 45 | 1.0 | 10-90 | 10-90 | 10-90 |
Ex.37 | 80 | 389 | 0.00 | 0.00 | 0.00 | 45 | 2.2 | 1-300 | non | non |
Ex.38 | 63 | 76 | 2.80 | 5.90 | 0.02 | 47 | 2.3 | 1-300 | 1-300 | non |
Ex.39 | 45 | 80 | 0.00 | 9.94 | 0.08 | 41 | 12.9 | 1-300 | 1-300 | non |
C.E.1 | 35 | 65 | 3.45 | 9.94 | 11.40 | 41 | 12.9 | 100-130 | 100-130 | 100-130 |
C.E.2 | 65 | 17 | 2.54 | 5.42 | 8.59 | 58 | 14.0 | non | non | non |
C.E.3 | 24 | 44 | 2.40 | 8.40 | 2.70 | 55 | 1.3 | 5-20 | 5-20 | 5-20 |
C.E.4 | 19 | 68 | 0.07 | 0.2 | 0.07 | 59 | 0.7 | 1-10 | non | non |
Examples and Comparative Examples of phenolsulfonic acid bath | ||||||||||
Tin-plating bath composition (g/l) | Bath temp. | Plating solution flow rate | Matte tinplate (A/dm2) | |||||||
Sn ions | Base acid | ENSA | EN | Fe ions | (°C) | (m/sec) | O.C.D .R. | G.O.C .D.R. | H.C.R .O.C. D.R. | |
Ex.21 | 97 | 85 | 0.07 | 0.07 | 0.40 | 35 | 18.9 | 1-550 | non | 1-550 |
Ex.22 | 55 | 289 | 0.00 | 0.00 | 0.13 | 60 | 8.7 | 1-400 | non | 1-400 |
Ex.23 | 41 | 128 | 0.13 | 0.00 | 3.45 | 35 | 5.0 | 1-300 | 1-300 | 1-300 |
Ex.24 | 78 | 391 | 5.46 | 0.00 | 7.54 | 32 | 3.5 | 1-300 | 1-300 | 1-300 |
Ex.25 | 55 | 24 | 9.80 | 0.08 | 6.12 | 41 | 9.0 | 1-400 | 1-400 | 1-400 |
Ex.26 | 97 | 106 | 2.54 | 0.00 | 0.86 | 54 | 15.7 | 1-500 | 1-500 | 1-500 |
Ex.27 | 51 | 256 | 3.00 | 0.00 | 14.70 | 45 | 2.1 | 1-300 | 1-300 | 1-300 |
Ex.28 | 45 | 80 | 0.00 | 9.94 | 11.40 | 41 | 12.9 | 1-300 | 1-300 | 1-300 |
Ex.29 | 65 | 356 | 0.07 | 5.42 | 8.59 | 58 | 14.0 | 1-500 | 1-500 | 1-500 |
Ex.30 | 78 | 321 | 0.00 | 0.16 | 2.45 | 60 | 6.0 | 1-400 | 1-400 | 1-400 |
Ex.31 | 42 | 264 | 0.00 | 2.25 | 7.26 | 55 | 8.6 | 1-300 | 1-300 | 1-300 |
Ex.32 | 52 | 180 | 3.40 | 0.40 | 0.47 | 58 | 4.0 | 1-300 | 1-300 | 1-300 |
Ex.33 | 63 | 76 | 2.80 | 5.90 | 3.00 | 47 | 2.3 | 1-300 | 1-300 | 1-300 |
Ex.34 | 68 | 195 | 8.70 | 6.00 | 7.00 | 51 | 18.9 | 1-500 | 1-500 | 1-500 |
Ex.35 | 68 | 195 | 8.70 | 6.00 | 7.00 | 51 | 1.8 | 10-150 | 10-150 | 10-150 |
Ex.36 | 49 | 84 | 2.65 | 2.87 | 3.26 | 45 | 1.0 | 10-90 | 10-90 | 10-90 |
Ex.37 | 80 | 389 | 0.00 | 0.00 | 0.00 | 45 | 2.2 | 1-300 | non | non |
Ex.38 | 63 | 76 | 2.80 | 5.90 | 0.02 | 47 | 2.3 | 1-300 | 1-300 | non |
Ex.39 | 45 | 80 | 0.00 | 9.94 | 0.08 | 41 | 12.9 | 1-300 | 1-300 | non |
C.E.1 | 35 | 65 | 3.45 | 9.94 | 11.40 | 41 | 12.9 | 100-130 | 100-130 | 100-130 |
C.E.2 | 65 | 17 | 2.54 | 5.42 | 8.59 | 58 | 14.0 | non | non | non |
C.E.3 | 24 | 44 | 2.40 | 8.40 | 2.70 | 55 | 1.3 | 5-20 | 5-20 | 5-20 |
C.E.4 | 19 | 68 | 0.07 | 0.2 | 0.07 | 59 | 0.7 | 1-10 | non | non |
Examples and Comparative Examples of methanesulfonic acid bath | ||||||||||
Tin-plating bath composition (g/l) | Bath temp. | Plating solution flow rate | Corrosion-resistant tinplate (A/dm2) | |||||||
Sn ions | Base acid | Brightener | Antioxidant | Fe ions | (°C) | (m/sec) | O.C.D .R. | G.O.C .D.R. | H.C.R .O.C. D.R. | |
Ex. 1 | 45 | 125 | 0.00 | 0.00 | 0.00 | 45 | 4.5 | 5-270 | non | non |
Ex. 2 | 75 | 389 | 0.00 | 0.00 | 4.50 | 45 | 2.3 | 5-270 | non | non |
Ex. 3 | 60 | 22 | 0.00 | 0.00 | 0.01 | 30 | 15.1 | 5-270 | non | non |
Ex. 4 | 98 | 85 | 3.00 | 0.02 | 0.00 | 34 | 18.8 | 5-450 | non | non |
Ex. 5 | 42 | 289 | 0.3 | 9.21 | 0.07 | 65 | 8.5 | 5-270 | non | non |
Ex. 6 | 41 | 128 | 8.99 | 5.22 | 8.20 | 35 | 4.9 | 5-300 | 5-300 | non |
Ex. 7 | 85 | 391 | 5.62 | 1.26 | 0.00 | 32 | 3.7 | 5-300 | 5-300 | non |
C.E.1 | 34 | 66 | 3.85 | 9.84 | 0.00 | 45 | 11.9 | 100-120 | 100-120 | 100-120 |
C.E.2 | 64 | 15 | 2.59 | 5.62 | 9.49 | 55 | 14.0 | non | non | non |
C.E.3 | 22 | 44 | 3.40 | 7.40 | 2.50 | 55 | 1.6 | 10-20 | 10-20 | 10-20 |
C.E.4 | 18 | 66 | 0.06 | 0.1 | 0.06 | 55 | 0.4 | 3-10 | non | non |
Examples and Comparative Examples of methanesulfonic acid bath | ||||||||||
Tin-plating bath composition (g/l) | Bath temp. | Plating solution flow rate | Matte (A/dm2) | tinplate | ||||||
Sn ions | Base acid | Brightener | Antioxidant | Fe ions | (°C) | (m/sec) | O.C.D .R. | G.O.C .D.R. | H.C.R .O.C. D.R. | |
Ex. 1 | 45 | 125 | 0.00 | 0.00 | 0.00 | 45 | 4.5 | 5-270 | non | non |
Ex. 2 | 75 | 389 | 0.00 | 0.00 | 4.50 | 45 | 2.3 | 5-270 | non | non |
Ex. 3 | 60 | 22 | 0.00 | 0.00 | 0.01 | 30 | 15.1 | 5-270 | non | non |
Ex. 4 | 98 | 85 | 3.00 | 0.02 | 0.00 | 34 | 18.8 | 5-450 | non | non |
Ex. 5 | 42 | 289 | 0.3 | 9.21 | 0.07 | 65 | 8.5 | 5-270 | non | non |
Ex. 6 | 41 | 128 | 8.99 | 5.22 | 8.20 | 35 | 4.9 | 5-300 | 5-300 | non |
Ex. 7 | 85 | 391 | 5.62 | 1.26 | 0.00 | 32 | 3.7 | 5-300 | 5-300 | non |
C.E.1 | 34 | 66 | 3.85 | 9.84 | 0.00 | 45 | 11.9 | 100-120 | 100-120 | 100-120 |
C.E.2 | 64 | 15 | 2.59 | 5.62 | 9.49 | 55 | 14.0 | non** | non** | non** |
C.E.3 | 22 | 44 | 3.40 | 7.40 | 2.50 | 55 | 1.6 | 10-20 | 10-20 | 10-20 |
C.E.4 | 18 | 66 | 0.06 | 0.1 | 0.06 | 55 | 0.4 | 3-10 | non | non |
Claims (21)
- A method for tin-plating, comprising plating a steel sheet with tin in a tin-plating bath containing from 40 to 100 g/l of Sn ions, the relative speed difference between the steel sheet to be plated and the plating solution being held at 2 to 20 m/sec, the plating being operated at an optimum current density the variation width of which is at least 80 A/dm2.
- The method for tin-plating according to claim 1, wherein the plating bath comprises 40 to 100 g/l of Sn ions and 20 to 400 g/l of phenolsulfonic acid.
- The method for tin-plating according to claim 1, wherein the plating bath comprises 40 to 100 g/l of Sn ions and 20 to 400 g/l of phenolsulfonic acid and further a brightener and/or an antioxidant.
- The method for tin-plating according to claim 1, wherein the plating bath comprises 40 to 100 g/l of Sn ions, 0.1 to 15 g/l of Fe ions and 20 to 400 g/l of phenolsulfonic acid.
- The method for tin-plating according to claim 1, wherein the plating bath comprises 40 to 100 g/l of Sn ions, 0.1 to 15 g/l of Fe ions and 20 to 400 g/l of phenolsulfonic acid, and further a brightener and/or antioxidant.
- The method for tin-plating according to claim 3, wherein the plating bath comprises, as the brightener 0.1 to 10 g/l of ethoxylated α-naphtholsulfonic acid and/or 0.1 to 10 g/l of ethoxylated α-naphthol.
- The method for tin-plating according to claim 5, wherein the plating bath comprises as the brightener 0.1 to 10 g/l of ethoxylated α-naphtholsulfonic acid and/or 0.1 to 10 g/l of ethoxylated α-naphthol.
- The method for tin-plating according to claim 1, wherein the plating bath comprises 40 to 100 g/l of Sn ions and 20 to 400 g/l of methanesulfonic acid.
- The method for tin-plating according to claim 1, wherein the plating bath comprises 40 to 100 g/l of Sn ions and 20 to 400 g/l of methanesulfonic acid, and further 0.1 to 10 g/l of a brightener and/or 0.1 to 10 g/l of an antioxidant.
- The method for tin-plating according to claim 1, wherein the plating bath comprises 40 to 100 g/l of Sn ions, 40 to 300 g/l of β-alkanolslulfonic acid which has a hydroxyl group at the β-position and which is typically represented by 2-hyroxyethan-1-sulfonic acid and a brightener.
- The method for tin-plating according to claim 1, wherein the variation width of the optimum current density is at least 250 A/dm2.
- The method for tin-plating according to claim 1, wherein the variation width of the optimum current density is at least 350 A/dm2.
- A tin-plating bath comprising 40 to 100 g/l of Sn ions and 20 to 400 g/l of phenolsulfonic acid.
- The tin-plating bath according to claim 13, wherein the tin-plating bath comprises 40 to 100 g/l of Sn ions and 20 to 400 g/l of phenolsulfonic acid, and further a brightener and/or an antioxidant.
- The tin-plating bath according to claim 13, wherein the tin-plating bath comprises 40 to 100 g/l of Sn ions, 0.1 to 15 g/l of Fe ions and 20 to 400 g/l of phenolsulfonic acid.
- The tin-plating bath according to claim 13, wherein the tin-plating bath comprises 40 to 100 g/l of Sn ions, 0.1 to 15 g/l of Fe ions and 20 to 400 g/l of phenolsulfonic acid, and further a brightener and/or an antioxidant.
- The tin-plating bath according to claim 14, wherein the tin-plating bath comprises as the brightener 0.1 to 10 g/l of ethoxylated α-naphtholsulfonic acid and/or 0.1 to 10 g/l of ethoxylated α-naphthol.
- The tin-plating bath according to claim 16, wherein the tin-plating bath comprises as the brightener 0.1 to 10 g/l of ethoxylated α-naphtholsulfonic acid and/or 0.1 to 10 g/l of ethoxylated α-naphthol.
- A tin-plating bath comprising 40 to 100 g/l of Sn ions and 20 to 400 g/l of methanesulfonic acid.
- The tin-plating bath according to claim 19, wherein the tin-plating bath comprises 40 to 100 g/l of Sn ions and 20 to 400 g/l of methanesulfonic acid, and further 0.1 to 10 g/l of a brightener and/or 0.1 to 10 g/l of an antioxidant.
- A tin-plating bath comprising 40 to 100 g/l of Sn ions, 40 to 300 g/l of β-alkanolslulfonic acid having a hydroxyl group at the β-position typically represented by 2-hyroxyethane-1-sulfonic acid, and a brightener.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP13562796 | 1996-02-29 | ||
JP135627/96 | 1996-02-29 | ||
PCT/JP1997/000625 WO1997032058A1 (en) | 1996-02-29 | 1997-02-28 | Tin plating method and bath having wide optimum current density range |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0889147A1 true EP0889147A1 (en) | 1999-01-07 |
Family
ID=15156232
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP97905428A Withdrawn EP0889147A1 (en) | 1996-02-29 | 1997-02-28 | Tin plating method and bath having wide optimum current density range |
Country Status (8)
Country | Link |
---|---|
EP (1) | EP0889147A1 (en) |
KR (1) | KR19990087386A (en) |
CN (1) | CN1218520A (en) |
AU (1) | AU718314B2 (en) |
BR (1) | BR9707796A (en) |
CA (1) | CA2247440A1 (en) |
TW (1) | TW412602B (en) |
WO (1) | WO1997032058A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7032471B2 (en) | 1999-12-16 | 2006-04-25 | O&K Orenstein Und Koppel Ag | Control device for controlling machines by hand or foot |
EP1754805A1 (en) * | 2005-08-19 | 2007-02-21 | Rohm and Haas Electronic Materials LLC | Tin electroplating solution and tin electroplating method |
CN105755513A (en) * | 2016-04-28 | 2016-07-13 | 四川昊吉科技有限公司 | Tinning preservative |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
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CN1993502B (en) * | 2004-08-05 | 2011-04-20 | 新日本制铁株式会社 | Method of electric tinning |
JP4742677B2 (en) * | 2005-05-24 | 2011-08-10 | Jfeスチール株式会社 | Method for producing tin-plated steel strip |
CN101388350B (en) * | 2008-10-30 | 2011-02-16 | 常州星海半导体器件有限公司 | Tinning method for SMD stamp-mounting-paper diode |
CN102345146A (en) * | 2011-09-22 | 2012-02-08 | 无锡市创威冷轧有限公司 | Novel cold-rolled steel sheet |
CN104562120A (en) * | 2015-01-23 | 2015-04-29 | 张家港市新港星科技有限公司 | Steel strip tinning method |
CN107723758A (en) * | 2016-08-12 | 2018-02-23 | 惠州大亚湾金盛科技有限公司 | A kind of tin plating additive |
CN111826690B (en) * | 2020-08-04 | 2021-07-13 | 烟台洛姆电子有限公司 | Formula and process of vertical high-speed continuous tin plating solution |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2667323B2 (en) * | 1991-04-01 | 1997-10-27 | 川崎製鉄株式会社 | Antioxidant, auxiliary for plating bath and plating bath using the same |
JPH05195283A (en) * | 1992-01-22 | 1993-08-03 | Kawasaki Steel Corp | Tin plating bath and method for tin plating |
JPH06346272A (en) * | 1993-06-14 | 1994-12-20 | Nippon Steel Corp | Sulfuric acid bath for tinning at high current density and tinning method |
JPH07157889A (en) * | 1993-12-03 | 1995-06-20 | Nippon Steel Corp | Production of plated steel sheet excellent in corrosion resistance |
-
1997
- 1997-02-27 TW TW086102627A patent/TW412602B/en active
- 1997-02-28 WO PCT/JP1997/000625 patent/WO1997032058A1/en not_active Application Discontinuation
- 1997-02-28 AU AU22311/97A patent/AU718314B2/en not_active Ceased
- 1997-02-28 BR BR9707796A patent/BR9707796A/en not_active Application Discontinuation
- 1997-02-28 EP EP97905428A patent/EP0889147A1/en not_active Withdrawn
- 1997-02-28 KR KR1019980706801A patent/KR19990087386A/en not_active Application Discontinuation
- 1997-02-28 CA CA002247440A patent/CA2247440A1/en not_active Abandoned
- 1997-02-28 CN CN97193376A patent/CN1218520A/en active Pending
Non-Patent Citations (1)
Title |
---|
See references of WO9732058A1 * |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7032471B2 (en) | 1999-12-16 | 2006-04-25 | O&K Orenstein Und Koppel Ag | Control device for controlling machines by hand or foot |
EP1754805A1 (en) * | 2005-08-19 | 2007-02-21 | Rohm and Haas Electronic Materials LLC | Tin electroplating solution and tin electroplating method |
CN1928164B (en) * | 2005-08-19 | 2010-05-12 | 罗门哈斯电子材料有限公司 | Tin electroplating solution and tin electroplating method |
CN105755513A (en) * | 2016-04-28 | 2016-07-13 | 四川昊吉科技有限公司 | Tinning preservative |
Also Published As
Publication number | Publication date |
---|---|
AU718314B2 (en) | 2000-04-13 |
WO1997032058A1 (en) | 1997-09-04 |
BR9707796A (en) | 1999-07-27 |
TW412602B (en) | 2000-11-21 |
CA2247440A1 (en) | 1997-09-04 |
CN1218520A (en) | 1999-06-02 |
KR19990087386A (en) | 1999-12-27 |
AU2231197A (en) | 1997-09-16 |
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