Note: Descriptions are shown in the official language in which they were submitted.
DESCRIPTION
Title of Invention
CHEMICAL CONVERSION TREATMENT SOLUTION AND CHEMICALLY
CONVERTED STEEL SHEET
Technical Field
[0001] The present invention relates to a chemically treated steel sheet, and
a chemical
treatment solution for a zinc-based plated steel sheet.
Background Art
[0002] Zinc-based plated steel sheets have been used in wide applications such
as
automobiles, building materials, and home electric appliances. Typically, the
surface of a
plated steel sheet is subjected to a chromium-free chemical treatment for
imparting
corrosion resistance without oiling. The chromium-free chemical treatment is
roughly
divided into organic treatments and inorganic treatments. The organic
treatments allow a
thick film containing an organic resin to be formed, whereas the inorganic
treatments allow
a thin film (film thickness: 1 gm or less) to be formed for obtaining spot
weldability. The
organic treatments can impart relatively high corrosion resistance compared to
the
inorganic treatments. Some of the inorganic treatments also exhibit high
corrosion
resistance in the same degree as the organic treatments by using a zinc-based
plated steel
sheet containing aluminum and magnesium in its plating layer as an original
sheet for
chemical treatment.
[0003] As the inorganic treatment, for example, titanium-based, zirconium-
based,
molybdenum-based, and their complex-based inorganic treatments have been
developed
depending on the difference in corrosion inhibitors. Further, in order to
enhance corrosion
resistance, inorganic treatments to which a silane coupling agent, silica sol,
an organic acid,
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or the like is further added have also been developed (see, e.g., PTLs 1 to
3).
[0004] PTL 1 discloses a chemically treated steel sheet obtained by forming a
chromium-free chemical conversion film containing a valve metal and a soluble
fluoride of
the valve metal on the surface of a zinc-based plated steel sheet. PTL 2
discloses a
v
chemically treated steel sheet obtained by forming a chromium-free chemical
conversion
film containing: a zirconium compound, a vanadyl compound (salt of V02+), and
the like;
an organic acid; a silica compound; a fluoride; a lubricant; or the like on
the surface of a
Magnesium-Aluminum-Silicon-containing zinc-based plated steel sheet. PTL 3
discloses
a chemically treated steel sheet obtained by forming a chromium-free chemical
conversion
film containing a basic zirconium compound, a vanadyl compound, a phosphate
compound,
a cobalt compound, an organic acid, or the like on the surface of a zinc-based
plated steel
sheet.
[0005] As disclosed in PTLs 1 to 3, chromium-free chemical treatments in which
corrosion inhibitors are complexed, and an organic acid, a fluoride, a silane
coupling agent,
or the like is added for the enhancement of the functionality of the chromium-
free chemical
conversion film, and which can impart more excellent corrosion resistance of
the film than
that of the film obtained by the conventional chromate treatments. However,
when the
chemically treated steel sheet obtained by forming the chromium-free chemical
conversion
film on the surface of the zinc-based plated steel sheet is stored for a long
period of time
under high temperature and humid environment, the chemically treated steel
sheet
sometimes has a blacked surface of a plating layer due to oxidization. The
blackening of
the surface of the plating layer not only lowers the design but also cause
adverse influences
such as lowering of spot weldability. This phenomenon is remarkably apparent
particularly in the zinc-based plated steel sheet containing aluminum and
magnesium in its
plating layer.
[0006] As a means for suppressing the blackening of the zinc-based plated
steel sheet,
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PTL 4 proposes an organic chemical treatment in which a hexavalent molybdenum
oxoate
and an amine coexist. According to the technique of PTL 4, an amine forms a
complex
with molybdenum oxo-acid to suppress the reaction of the molybdenum oxoate
with a zinc
alloy plating layer, and thus a pentavalent or hexavalent molybdenum complex
oxoate
(so-called "molybdenum blue") is formed in the chemical conversion film. The
pentavalent molybdenum oxoate in the chemical conversion film becomes the
hexavalent
molybdenum oxoate through the reaction with oxygen which permeates the film.
In this
manner, the pentavalent molybdenum oxoate in the chemical conversion film
traps oxygen
which permeates the film, so that the oxidation of the surface of the plating
layer is
suppressed, and as a result the blackening is also suppressed.
Citation List
Patent Literature
[0007]
PTL 1
Japanese Patent Application Laid-Open No. 2002-194558
PTL 2
Japanese Patent Application Laid-Open No. 2003-055777
PTL 3
W02007/123276
PTL 4
Japanese Patent Application Laid-Open No. 2005-146340
Summary of Invention
Technical Problem
[0008] In order to impart high corrosion resistance to a chemically treated
steel sheet, it is
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necessary to dry a chemical treatment solution applied to the surface of the
steel sheet
sufficiently to form an insoluble film. When the drying temperature is low and
drying is
insufficient, corrosion resistance is remarkably lowered. Therefore, when the
chemically
= treated steel sheet is produced in a continuous line, it is necessary to
dry the chemical
treatment solution at a high temperature of a steel sheet temperature of about
50 to 200 C,
from the viewpoint of both achieving sufficient drying and productivity.
[0009] Recently, CO2 elimination as a countermeasure for global warming and
power
saving as a countermeasure for power shortage have been required. In
particular, in order
to cope with Scope 3, products have been required, which contribute to CO2
elimination
.. even in the stage in which raw materials for the products are produced.
Accordingly, also
in the chromium-free chemical treatment, it has been required to lower the
drying
temperature and reduce the drying time.
[0010] The present invention has been achieved in light of the above-mentioned
respects,
and an object of the present invention is to provide a chemically treated
steel sheet which is
excellent in corrosion resistance and blackening resistance obtained by
employing a
zinc-based plated steel sheet as an original sheet, and which is capable of
being produced
even when an applied chemical treatment solution is dried at a low temperature
and for a
short period of time.
[0011] Another object of the present invention is to provide a chemical
treatment solution
capable of forming a chemical conversion film that enhances corrosion
resistance and
blackening resistance even when being dried at a low temperature and for a
short period of
time.
Solution to Problem
[0012] The present inventors have studied the chromium-free chemical treatment
for the
zinc-based plated steel sheet in terms of the relationship between treatment
conditions
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(such as the composition of the chemical conversion film and drying
temperature) and
various quality properties. As a result, the present inventors have found it
important to
form an insoluble complex film with small residual amount of a soluble salt
and a solvent,
for the enhancement of corrosion resistance. That is, it has been found that,
when
excessive amounts of a fluoride, an organic acid, and an amine with a high-
boiling point
remain in the chemical conversion film, corrosion resistance is remarkably
lowered.
Particularly, it has been found that, the composition of the chemical
treatment solution is
quite important, because when the chemical treatment solution is dried at a
low
temperature and for a short period of time, a complex salt is less likely to
be formed, and a
fluoride, an organic acid, and an amine with a high-boiling point tend to
remain.
[0013] As a result of intensive study in consideration of those respects, the
present
inventors have found that the above-described problems can be solved by
forming a
chemical conversion film using a chemical treatment solution containing a
water-soluble
molybdate, a vanadium salt, an amine having a low boiling point, a group 4A
metal oxoate
and a phosphate, and have studied further to complete the present invention.
[0014] That is, the present invention relates to the following chemical
treatment solution:
[1] A chemical treatment solution for coating a zinc-based plated steel sheet
having a
zinc-based plating layer containing 0.1 to 22.0 mass % of aluminum, the
chemical
treatment solution containing a water-soluble molybdate, a vanadium salt, an
amine, a
group 4A metal oxoate and a phosphate compound, in which a molar ratio of
molybdenum
to vanadium in the chemical treatment solution is 0.4 to 5.5, a molar ratio of
the amine to
the vanadium in the chemical treatment solution is 0.3 or more, a content of a
hydrophilic
resin in the chemical treatment solution is at most 100 mass % based on a
total amount of
the vanadium and the molybdenum in the chemical treatment solution, a total
content of
fluorine derived from a fluorine ion or a fluorometal ion in the chemical
treatment solution
is at most 30 mass % based on the total amount of the vanadium and the
molybdenum in
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the chemical treatment solution, and a content of silicon derived from a
silanol group in the
chemical treatment solution is at most 50 mass % based on the total amount of
the
vanadium and the molybdenum in the chemical treatment solution.
[2] The chemical treatment solution according to [1], in which the amine has a
molecular
weight of 80 or less.
[0015] Further, the present invention relates to the following chemically
treated steel
sheet:
[3] A chemically treated steel sheet including a zinc-based plated steel sheet
having a
zinc-based plating layer containing 0.1 to 22.0 mass % of aluminum, and a
chemical
conversion film disposed on the zinc-based plating layer, in which the
chemical conversion
film includes a first chemical conversion layer disposed on a surface of the
zinc-based
plating layer and containing vanadium, molybdenum and phosphorus, and a second
chemical conversion layer disposed on the first chemical conversion layer and
containing a
group 4A metal oxoate, and a percentage of pentavalent vanadium based on mixed-
valent
vanadium in the chemical conversion film
is 0.7 or more.
[4] The chemically treated steel sheet according to [3], in which the group 4A
metal oxoate
is a zirconium oxoate, and the chemical conversion film contains 1 to 60 parts
by mass of
molybdenum, 2 to 20 parts by mass of vanadium, and 10 to 50 parts by mass of
phosphorus,
based on 100 parts by mass of zirconium.
[5] The chemically treated steel sheet according to [3] or [4], in which the
zinc-based
plated steel sheet is a hot-dip aluminum- and magnesium-containing zinc plated
steel sheet
having a hot-dip aluminum- and magnesium-containing zinc plating layer
containing 0.1 to
22.0 mass % of aluminum and 1.5 to 10.0 mass % of magnesium.
Advantageous Effects of Invention
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[0016] According to the present invention, it is possible to produce a
chemically treated
steel sheet excellent in corrosion resistance and blackening resistance even
when a
chemical treatment solution applied to the surface of a zinc-based plated
steel sheet is dried
at a low temperature and for a short period of time.
Brief Description of Drawings
[0017]
FIG. 1 is a TEM image of a cross-section of a test specimen of one example of
a
chemically treated steel sheet according to the present invention produced at
a drying
temperature of 80 C;
FIG. 2 is a diagram showing an element distribution of the test specimen from
the
surface thereof toward the depth direction; and
FIG 3 is a diagram showing the intensity profile of chemical binding energy
corresponding to 2p orbit of vanadium in an interface between a chemical
conversion film
and plating layer interface of a test specimen of the other example of the
chemically treated
steel sheet according to the present invention.
Description of Embodiments
[0018] A chemically treated steel sheet of the present invention includes a
zinc-based
plated steel sheet (original sheet for chemical treatment) and a chemical
conversion film
formed on a surface of the zinc-based plated steel sheet. Hereinafter, each
constituent
element will be described.
[0019] [Zinc-Based Plated Steel Sheet]
As the original sheet for chemical treatment, a zinc-based plated steel sheet
excellent in corrosion resistance and design is used. As used herein, the term
"zinc-based
plated steel sheet" means a plated steel sheet having a zinc-based plating
layer containing
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0.1 to 22.0 mass % of aluminum and 50 mass % or more of zinc. Examples of the
zinc-based plated steel sheet include hot-dip zinc plated steel sheet (GI),
alloyed hot-dip
zinc plated steel sheet (GA), hot-dip zinc-aluminum plated steel sheet, and
hot-dip
zinc-aluminum-magnesium plated steel sheet. The plating layers of the hot-dip
zinc
plated steel sheet (GI) and alloyed hot-dip zinc plated steel sheet (GA) also
contain 0.1
mass % or more of aluminum for preventing oxidation. The zinc-based plated
steel sheet
may be produced by a hot-dip plating process, an electroplating process, a
vapor-deposition
plating process, or the like.
[0020] For example, the hot-dip zinc-aluminum-magnesium plated steel sheet can
be
produced by the hot-dip plating process using an alloy plating bath containing
1.0 to 22.0
mass % of aluminum and 1.5 to 10.0 mass % of magnesium, with the residual part
being
substantially zinc. In order to enhance the adherence between a steel
substrate and a
plating layer, silicon which suppresses the growth of an aluminum-iron alloy
layer in the
interface between the steel substrate and the plating layer may be added to
the plating bath
in a range of 0.005 to 2.0 mass %. Further, in order to suppress the
generation and the
growth of Zm1Mg2 phase which causes adverse influence on its outer appearance
and
corrosion resistance, titanium, boron, a titanium-boron alloy, a titanium-
containing
compound or a boron-containing compound may be added to the plating bath. The
addition amounts of these compounds are preferably set such that titanium is
within a range
of 0.001 to 0.1 mass % and boron is within a range of 0.0005 to 0.045 mass %.
[0021] The type of the steel substrate of the zinc-based plated steel sheet is
not
particularly limited. Examples of the steel substrate include common steel,
low alloy
steel, and stainless steel.
[0022] [Chemical Conversion Film]
A chemical conversion film is formed on the surface of the zinc-based plated
steel
sheet. The chemical conversion film enhances the corrosion resistance and
blackening
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resistance of the zinc-based plated steel sheet. The chemical conversion film
includes a
first chemical conversion layer (reaction layer) positioned on the surface of
the zinc-based
plated steel sheet and principally composed of vanadium, molybdenum and
phosphorus,
and a second chemical conversion layer positioned on the first chemical
conversion layer
and principally composed of a group 4A metal oxoate.
[0023] As used herein, the term "corrosion resistance" includes one or both of
flat part
corrosion resistance and worked part corrosion resistance. "Worked part
corrosion
resistance" is corrosion resistance of a part subjected to working (working
part) such as
bending work in which a chemically treated steel sheet is deformed, and "flat
part
corrosion resistance" is corrosion resistance of a part other than the working
part in the
chemically treated steel sheet.
[0024] [Chemical Treatment Solution]
The chemical conversion film is formed by applying and drying an alkaline
chemical treatment solution containing 1) a water-soluble molybdate, 2) a
vanadium salt,
3) an amine having a low boiling point, 4) a group 4A metal oxoate, and 5) a
phosphate.
By adjusting the pH of the chemical treatment solution to be alkaline, it is
possible to form
the first chemical conversion layer (reaction layer) without using fluorine or
the like even
on an aluminum part of the surface of the plating layer having less
reactivity. By using
the chemical treatment solution of such a composition, it becomes possible to
form a
chemical conversion film which may enhance the corrosion resistance and
blackening
resistance of the zinc-based plated steel sheet, even when the chemical
treatment solution is
dried at a low temperature and for a short period of time. Note that vanadium
derived
from the vanadium salt, molybdenum derived from the water-soluble molybdate
and
phosphorus derived from the phosphate are localized in the first chemical
conversion layer.
Further, the group 4A metal oxoate is localized in the second chemical
conversion layer.
Hereinafter, each element contained in the chemical treatment solution will be
described.
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[0025] 1) Molybdate
A molybdate stabilizes the valence of vanadium in the chemical treatment
solution,
and enhances the blacking resistance and corrosion resistance of the
chemically treated
steel sheet. It is deduced that a molybdenum acid ion (hereinafter, also
referred to as Mo
acid ion) forms a complex with a pentavalent vanadium ion (hereinafter, also
referred to as
pentavalent V ion) in the alkaline chemical treatment solution to thereby
stabilize the
valence of vanadium so as to be pentavalent.
[0026] The molar ratio of molybdenum to vanadium in the chemical treatment
solution,
i.e., the molar ratio of a molybdenum element derived from a molybdate to a
vanadium
element derived from a vanadium salt (MoN) in the chemical treatment solution
is within
a range of 0.4 to 5.5. When the molar ratio of the molybdenum element to the
vanadium
element is less than 0.4, there is a concern that the valence of vanadium
cannot be kept to
be pentavalent. When the molar ratio of the molybdenum element to the vanadium
element is more than 5.5, a Mo acid ion is more likely to form a condensed
acid, and the
Mo acid ion that forms a complex with the pentavalent V ion becomes
insufficient, so that
there is a concern that the valence of V may not be stable.
Further, when a chemical conversion film is formed using a chemical treatment
solution in which a molybdate and an amine coexist, a pentavalent or
hexavalent
molybdenum complex oxoate is formed in the chemical conversion film.
[0027] When a chemical conversion film is formed, in an alkaline condition,
using the
chemical treatment solution in which a vanadium salt, a molybdate and an amine
coexist,
molybdenum preferentially reacts with the surface of the plating layer
together with the
vanadium salt and phosphorus to form a first chemical conversion layer
(reaction layer) on
the surface of the plating layer. In this manner, the molybdate forms a
uniform reaction
layer on the surface of the plating layer together with vanadium acid and the
phosphorus,
and thus blackening resistance is enhanced. Further, due to the coexistence of
the
CA 3026697 2018-12-06
molybdate and the amine, a pentavalent or hexavalent molybdenum complex oxoate
is
formed in the chemical conversion film, which pentavalent molybdenum oxoate is
oxidized
to thereby form an oxidized film; the oxidized film also contributes to the
enhancement of
corrosion resistance. In addition, when the above-described lattice defect
occurs, the
plating layer is considered to exhibit a gray outer appearance with metal
luster being
suppressed further due to more absorption of light of a wavelength in visible
region.
[0028] The type of the molybdate is not particularly limited as long as the
molybdate can
perform the above-mentioned functions.
Examples of the molybdate include
molybdenum acid, ammonium molybdate, and a molybdenum acid alkali metal salt.
Among those, molybdenum acid or ammonium molybdate is particularly preferred
from
the viewpoint of corrosion resistance. The amount of molybdenum contained in
the
chemical conversion film is preferably within a range of 1 to 60 parts by mass
based on
100 parts by mass of a group 4A metal (e.g., zirconium). When the amount of
molybdenum is less than 1 part by mass, there is a concern that the blackening
resistance
cannot be sufficiently enhanced. When the amount of molybdenum is more than 60
parts
by mass, the amount of a molybdate unreacted with the surface of the plating
layer
becomes excessive, so that there is a concern that working part corrosion
resistance may be
lowered.
[0029] 2) Vanadium Salt
A vanadium salt contributes not only to the enhancement of corrosion
resistance
but also to the enhancement of blackening resistance. When a chemical
conversion film
is formed, in an alkaline condition, using a chemical treatment solution in
which a
vanadium salt, a molybdate and an amine coexist, vanadium preferentially
reacts with the
surface of the plating layer together with molybdenum acid and phosphorus to
form a first
chemical conversion layer (reaction layer) on the surface of the plating
layer. In this
manner, vanadium forms a uniform reaction layer on the surface of the plating
layer
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together with molybdenum acid and a group 4A metal, and thus corrosion
resistance and
blackening resistance are enhanced.
[0030] The type of the vanadium salt is not particularly limited as long as
the vanadium
salt can perform the above-mentioned functions. Examples of the vanadium salt
include
ammonium metavanadate, sodium metavanadate, potassium metavanadate, and a
vanadate
obtained by dissolving vanadium pentoxide with an amine. In all of these
vanadium salts,
the valence of vanadium is pentavalent (hereinafter, vanadium having a valence
of 5 is also
referred to as "pentavalent V"). Among those, ammonium metavanadate, or a
vanadate
obtained by dissolving vanadium pentoxide with an amine is particularly
preferred from
the viewpoint of corrosion resistance.
[0031] Generally, the pentavalent V ion in the chemical treatment solution has
low
stability of valence. Accordingly, if the pentavalent V ion in the chemical
treatment
solution is left alone, the concentration of the pentavalent V ion fails to
reach a
concentration at which the above-mentioned reaction layer is formed. Thus, as
described
above, the coexistence with the molybdate in an alkaline condition increases
the
concentration of the pentavalent V ion in the chemical treatment solution.
Further, it is
considered that the pentavalent V ion does not have higher solubility in the
chemical
treatment solution than a divalent to tetravalent vanadium ion chelated
through reduction
by an organic acid or the like, and thus is more likely to preferentially
precipitate on the
surface of the plating layer to generate a reaction.
[0032] The content of the vanadium salt in the chemically treatment solution
is
preferably 8 g/L or less in terms of vanadium atom. When this content is more
than 8 g/L,
the stability of the chemical treatment solution is lowered, so that there is
a possibility of
the formation of a precipitate when the chemical treatment solution is stored
at room
temperature for about a month. In this connection, in a case where the
chemical treatment
solution is used immediately after the production thereof, the above-mentioned
problem of
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stability does not occur even when the above-mentioned content is more than 8
g/L.
[0033] The amount of vanadium contained in the chemical treatment solution is
preferably within a range of 2 to 20 parts by mass based on 100 parts by mass
of a group
= 4A metal (e.g., zirconium). When the amount of vanadium is less than 2
parts by mass,
there is a concern that the corrosion resistance and blackening resistance
cannot be
enhanced sufficiently. When the amount of vanadium is more than 20 parts by
mass,
there is a concern that the amount of pentavalent vanadium unreacted with the
surface of
the plating layer may become excessive, causing the corrosion resistance to be
lowered.
[0034] The percentage of pentavalent vanadium based on mixed-valent vanadium
in the
chemical conversion film is 0.7 or more. When the percentage of pentavalent
vanadium
based on mixed-valent vanadium is less than 0.7, there is a concern that the
blackening
resistance cannot be enhanced sufficiently.
[0035] 3) Amine
An amine dissolves a salt containing pentavalent vanadium (hereafter, also
referred to as "pentavalent vanadium salt") in the chemical treatment solution
while
keeping the valence of vanadium to be pentavalent (tetravalent when an organic
acid is
used), and also forms a pentavalent or hexavalent molybdenum complex oxoate
from a
molybdate. The amine is preferably an amine having a low boiling point. The
amine
having a low boiling point is an amine having a molecular weight of 80 or
less. The
amine having a molecular weight of 80 or less generally has a low boiling
point, and hardly
remains in a chemical conversion film even when the chemical treatment
solution is dried
at a low temperature and for a short period of time, so that the amine can
contribute to the
enhancement of the corrosion resistance. Examples of the amine having a low
boiling
point include ammonia (used as aqueous ammonia), ethanolamine, 1-amino-2-
propanol,
and ethylenediamine. When an excessive amount of amine remains in the chemical
conversion film after being dried, the corrosion resistance of a chemically
treated steel
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sheet is undesirably lowered due to elution of an amine. Therefore, the amount
of the
amine remaining in the chemical conversion film is preferably 10 mass % or
less in terms
of nitrogen from the viewpoint of preventing the lowering of the corrosion
resistance of the
= chemically treated steel sheet. By using an amine having a molecular
weight of 80 or less,
the amount of the remaining amine can be 10 mass % or less in terms of
nitrogen.
[0036] By dissolving a pentavalent vanadium salt in a liquid amine or an
aqueous amine
solution, the pentavalent vanadium salt having low water-solubility can be
blended into a
chemical treatment solution while keeping the valence of vanadium to be
pentavalent.
When dissolving the pentavalent vanadium salt in a liquid amine, the addition
of the
resultant solution to the aqueous solution containing a molybdate enables a
chemical
treatment solution to be prepared. In addition, when dissolving the
pentavalent vanadium
salt in an aqueous amine solution, a pentavalent vanadium salt may be added
after the
molybdate and the amine to thereby directly prepare a chemical treatment
solution, or a
pentavalent vanadium salt may be dissolved in the aqueous amine solution, and
then the
resultant solution may be added to the aqueous solution containing a molybdate
to prepared
a chemical treatment solution. Typically, an aqueous solution containing
tetravalent
vanadium (V4 ) is blue, whereas an aqueous solution containing pentavalent
vanadium
(V5) is yellow, and thus it is possible to presume the valence of vanadium
from the color
of the chemical treatment solution.
[0037] As described above, when using a vanadate as a vanadium salt, vanadium
pentoxide is dissolved in an amine to prepare a vanadate. At that time, heat
is generated
in dissolving pentavalent vanadium in an amine. There is a concern that the
pentavalent
vanadium may be reduced to tetravalent vanadium in a high temperature
environment of
40 C or higher. Thus, in order to dissolve the pentavalent vanadium salt in an
amine
while keeping the valence of vanadium to be pentavalent, it is necessary to
maintain an
environmental temperature of the pentavalent vanadium less than 40 C. The
method in
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which the environmental temperature is maintained less than 40 C is not
particularly
limited. For example, the addition of vanadium pentoxide to the amine solution
(dilution
of amine and vanadium pentoxide) can maintain the environmental temperature
less than
40 C.
[0038] The molar ratio of the amine to vanadium in the chemical treatment
solution is 0.3
or more. When this molar ratio is less than 0.3, there is a concern that the
valence of
vanadium cannot be kept to be pentavalent. The molar ratio of the amine to
vanadium is
preferably 10 or less from the viewpoints of not allowing the effect of
maintaining the
valence of vanadium to reach a plateau, and of suppressing the cost of amine.
[0039] 4) Group 4A Metal Oxoate
A group 4A metal oxoate forms a dense chemical conversion film to enhance
corrosion resistance. That is, while it is difficult to form a dense chemical
conversion
film with a chemical treatment solution containing only a molybdate and a
vanadium salt,
it is possible to form a chemical conversion film having a high barrier
property by
cross-linking molybdenum and vanadium with the further addition of the group
4A metal
oxoate.
[0040] The type of the group 4A metal oxoate is not particularly limited.
Examples of
the group 4A metal oxoate include titanium, zirconium, and hafnium. Examples
of the
type of oxoate include hydracid salt, ammonium salt, alkaline metal salt, and
alkaline earth
metal salt. Among those, a group 4A metal oxoate ammonium salt is preferred,
and
ammonium zirconium carbonate is particularly preferred, from the viewpoint of
corrosion
resistance.
[0041] 5) Phosphate
The chemical treatment solution further contains a phosphate. The phosphate
functions with the group 4A metal oxoate to thereby form a dense chemical
conversion
film, thus enhancing corrosion resistance. The type of the phosphate is not
particularly
CA 3026697 2018-12-06
limited as long as the phosphate can perform the above-mentioned functions.
Examples
of the phosphate include an alkali metal phosphate, and an ammonium phosphate.
In
particular, diammonium hydrogen phosphate or ammonium dihydrogen phosphate,
which
can sufficiently enhance corrosion resistance, is preferred, even when being
dried at a low
temperature and for a short period of time. The amount of phosphorus in the
chemical
conversion film is preferably in a range of 10 to 50 parts by mass based on
100 parts by
mass of the group 4A metal (e.g., zirconium). When the amount of phosphorus is
less
than 10 parts by mass, a crack which constitutes a defect is more likely to
occur in the
chemical conversion film, so that there is a concern that the corrosion
resistance may be
lowered. When the amount of phosphorus is more than 50 parts by mass, an
unreacted
phosphate remains in the chemical conversion film, so that there is a concern
that the
corrosion resistance may be lowered.
[0042] Noted that, when specific component used in the conventional chromium-
free
chemical treatment is added to the above-mentioned chemical treatment
solution, the
expected characteristics of the chemically treated steel sheet may be
insufficient. For
example, a certain type of organic resin, silane coupling agent, or organic
acid is added, a
pentavalent V ion is more likely to be reduced to a tetravalent vanadium ion,
so that
blackening resistance may be lowered. Further, a functional group having a
polarity is
adsorbed to the plating surface, and thus the formation of a reaction layer at
that portion is
inhibited, so that there is a concern that corrosion resistance may be
lowered. This
phenomenon may be also observed when a film-forming aid (solvent such as butyl
cellosolve) for forming a film from an aqueous organic resin at a low
temperature is added.
Thus, it is preferable for the chemical treatment solution of the present
invention not to
contain the organic acid, organic resin, silane coupling agent, and film-
forming aid.
[0043] The above-mentioned specific component is not substantially contained
in the
chemical treatment solution. That is, the chemical treatment solution may be
substantially
16
CA 3026697 2018-12-06
composed of the above-mentioned component. As used herein, the term "not
substantially contained" means that "may be contained in such a range that the
above-described effects of the present invention are achieved," and also means
that
"preferably not contained at all from the viewpoint of remarkably achieving
the
above-described effects of the present invention." Examples of the specific
component
include a hydrophilic resin, fluorine derived from a fluorine ion or a
fluorometal ion, and
silicon derived from a silanol group.
[0044] The hydrophilic resin is a resin dissolved or dispersed evenly in an
aqueous
medium, and contains a hydrophilic functional group in an amount enough to
allow the
resin to be dissolved or dispersed evenly in the aqueous medium. The
hydrophilic resin
may also be referred to as an aqueous resin. Either one type of the
hydrophilic resin or
two or more types thereof may be employed. Examples of the hydrophilic resin
include a
resin which is dissolved or evenly dispersed in an aqueous medium to increase
the
viscosity of the aqueous medium; more specific examples thereof include
acrylic resin, a
polyolefin, epoxy resin, and polyurethane, which have the hydrophilic
functional group as
necessary due to modification. Examples of the hydrophilic functional group
include a
hydroxyl group, a carboxyl group, and an amino group. Either one type of the
hydrophilic functional group or two or more types thereof may be employed, as
well.
[0045] Incidentally, on the surface of the zinc-based plated steel sheet,
there exists a polar
group which typically exists on the surface of a metal, such as a hydroxyl
group. The
above-mentioned reaction layer is considered to be formed through a specific
interaction of
the polar group with component which constitutes the reaction layer, such as
molybdenum
and vanadium in the chemical treatment solution.
[0046] Accordingly, it is considered that, when there exists a large amount of
the
hydrophilic resin in the chemical treatment solution, the hydrophilic
functional group
undergoes an interaction such as hydrogen bonding or dehydration condensation
with the
17
CA 3026697 2018-12-06
polar group on the surface of the zinc-based plated steel sheet, so that the
polar group to
interact with a component in the reaction layer becomes insufficient relative
to the
component in the reaction layer, and as a result the formation of the reaction
layer is
inhibited, causing the expected characteristics of the chemically treated
steel sheet to be
insufficient.
[0047] For the above-mentioned reasons, the acceptable content of the
hydrophilic resin
in the chemical treatment solution is at most 100 mass % (i.e., 100 mass % or
less) based
on the total amount of vanadium and molybdenum in the chemical treatment
solution.
When the content of the hydrophilic resin is more than 100 mass %, the
formation of the
reaction layer is inhibited, so that the expected functions such as corrosion
resistance and
blackening resistance in the chemically treated steel sheet may be
insufficient. From the
viewpoint of sufficiently exhibiting expected functions in the chemically
treated steel sheet,
the content of the hydrophilic resin is preferably as small as possible; for
example, the
content thereof is preferably 50 mass % or less, more preferably 20 mass % or
less, and
most preferably 0 mass %.
[0048] The fluorine derived from a fluorine ion or a fluorometal ion may
exhibit etching
actions on the surface of the zinc-based plated steel sheet to form a layer of
a fluoride.
Examples of the fluorine include F- and MF62-. As used herein, "M" denotes a
tetravalent
metal element, for example, zirconium, titanium, or silicon.
Examples of the
above-mentioned component which serves as an origin of the fluorine include
potassium
fluoride (KF), ammonium titanium fluoride ((NH4)2Ti176), and hydrofluosilicic
acid
(H2SiF6). Either one type of the fluorine or two or more types thereof may be
employed.
[0049] It is considered that, when there exists a large amount of the fluorine
in the
chemical treatment solution, the surface of the zinc-based plated steel sheet
is dissolved by
the etching action of the fluorine, and the fluorine in the chemical treatment
solution is
concentrated on the dissolved portion, with a fluoride thin layer being formed
on the
18
CA 3026697 2018-12-06
surface of the zinc-based plated steel sheet, so that the polar group, which
is exposed to the
surface of the zinc-based plated steel sheet, to interact with the component
in the reaction
layer becomes insufficient relative to the component in the reaction layer,
resulting in the
inhibition of the formation of the reaction layer, causing the expected
characteristics of the
chemically treated steel sheet to be insufficient. Examples of the component
that occurs
due to the dissolution of the surface of the zinc-based plated steel sheet
include Zn2+, Al3+,
and Mg2+, and examples of the fluoride include ZnF2, A1F3, and MgF2. It is
noted that the
fluoride can be confirmed on the chemically treated steel sheet by X-ray
photoelectron
spectroscopy (XPS).
[0050] For the above-mentioned reasons, the total content of the fluorine
derived from a
fluorine ion or a fluorometal ion in the chemical treatment solution is at
most 30 mass %
(i.e., 30 mass % or less) based on the total amount of vanadium and molybdenum
in the
chemical treatment solution. When the content of the fluorine is more than 30
mass %,
the formation of the reaction layer may be inhibited, so that the expected
functions such as
corrosion resistance and blackening resistance in the chemically treated steel
sheet may be
insufficient. From the viewpoint of sufficiently exhibiting expected functions
in the
chemically treated steel sheet, the content of the fluorine is preferably as
small as possible;
for example, the content thereof is preferably 10 mass % or less, more
preferably 5 mass %
or less, and most preferably 0 mass %.
[0051] The silicon derived from a silanol group has a hydroxyl group.
Accordingly, it is
considered that, when the chemical treatment solution contains the silicon,
the existence of
the silicon derived from a silanol group inhibits the formation of the
reaction layer, for the
similar reason to those for the hydrophilic resin. That is, it is considered
that, when there
exists a large amount of the silicon in the chemical treatment solution, the
hydrophilic
group in the silanol group undergoes an interaction such as hydrogen bonding
or
dehydration condensation with the polar group on the surface of the zinc-based
plated steel
19
CA 3026697 2018-12-06
sheet, so that the polar group to interact with a component in the reaction
layer becomes
insufficient relative to the component in the reaction layer, and as a result
the formation of
the reaction layer is inhibited, causing the expected characteristics of the
chemically treated
= steel sheet to be insufficient. Examples of the component which serves as
an origin of the
silicon include a silane coupling agent; more specific examples thereof
include
3-aminopropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and
vinylethoxysilane.
[0052] For the above-mentioned reasons, the content of the silicon derived
from a silanol
group in the chemical treatment solution is at most 50 mass % (i.e., 50 mass %
or less)
based on the total amount of vanadium and molybdenum in the chemical treatment
solution.
When the content of the silicon is more than 50 mass %, the formation of the
reaction layer
may be inhibited, so that the expected functions such as corrosion resistance
and
blackening resistance in the chemically treated steel sheet may be
insufficient. From the
viewpoint of sufficiently exhibiting expected functions in the chemically
treated steel sheet,
the content of the silicon is preferably as small as possible; for example,
the content thereof
is preferably 20 mass % or less, more preferably 10 mass % or less, and most
preferably 0
mass %.
[0053] The existence and the content of the hydrophilic resin, fluorine, or
silicon in the
chemical treatment solution can be determined using known analyzers such as
infrared
spectroscopy (IR) spectrometer, nuclear magnetic resonance (NMR) spectrometer,
inductively coupled plasma (ICP) emission analyzer, and fluorescent X-ray
analyzer.
[0054] The method of identifying the structure of a chemical conversion film
is not
particularly limited. For example, it is possible to confirm that a chemical
conversion
film includes the first chemical conversion layer and the second chemical
conversion layer,
by observing the cross-section of a chemically treated steel sheet using a
transmission
electron microscope (IBM). Further, energy dispersive X-ray measurement (EDS)
can be
used to identify a component contained in each chemical conversion layer.
Furthermore,
CA 3026697 2018-12-06
glow discharge optical emission spectrometry (GDS) can be used to identify the
distribution of each component. Moreover, X-ray photoelectron spectroscopy
(XPS) can
be used to identify the percentage of pentavalent vanadium based on the mixed-
valent
= vanadium in the chemical conversion film.
[0055] [Method of Formation of Chemical Conversion Film]
As described above, a chemical conversion film is formed by applying a
chemical
treatment solution containing the above-mentioned each component to the
surface of a
zinc-based plated steel sheet, and drying the same.
[0056] The application method of the chemical treatment solution is not
particularly
limited. Examples of the application method of the chemical treatment solution
include
roll coating method, spin coating method, and spray coating method. The
deposition
amount of the chemical treatment solution is preferably within a range of 50
to 1,000
mg/m2. When the deposition amount is less than 50 mg/m2, corrosion resistance
cannot
be sufficiently enhanced. When the deposition amount is more than 1,000 mg/m2,
corrosion resistance undesirably becomes excessive. Furthermore, taking
account of spot
weldability, the deposition amount of the chemical conversion film is more
preferably
within a range of 50 to 500 mg/m2.
[0057] The drying temperature of the chemical treatment solution (a
temperature of the
sheet) may be an ordinary temperature, but is preferably 30 C or higher. The
chemical
treatment solution of the present invention can enhance corrosion resistance
and blackening
resistance even when being dried at a low temperature and for a long period of
time.
When the drying temperature exceeds 120 C, a crack undesirably occurs due to
the volume
shrinkage of the chemical conversion film as a result of, for example, rapid
decomposition
of ammonia components, so that there is a concern that the corrosion
resistance of the
chemically treated steel sheet may be lowered. Therefore, the drying
temperature of the
chemical treatment solution is within a range of preferably 30 to 120 C, and
more
21
CA 3026697 2018-12-06
preferably 35 to 85 C.
[0058] As described above, the chemical treatment solution according to the
present
invention contains the above-mentioned water-soluble molybdate, vanadium salt,
amine,
group 4A metal oxoate, and phosphate compound, and the molybdate and amine are
contained at the above-mentioned specific ratio to the vanadium salt. In
addition, the
chemical treatment solution of the present invention neither contains the
above-mentioned
hydrophilic resin, nor fluorine derived from a fluorine ion or a fluorometal
ion, nor silicon
derived from a silanol group, or alternatively only contains these elements up
to the
above-mentioned specific acceptable amount. Since such a chemical treatment
solution is
used for production, the chemically treated steel sheet of the present
invention includes a
zinc-based plated steel sheet, vanadium, molybdenum, phosphorus, and a group
4A metal
oxoate, and including a two-layer structure of the first chemical conversion
layer and the
second chemical conversion layer. Therefore, the chemically treated steel
sheet of the
present invention is excellent in corrosion resistance and blackening
resistance even when
the chemical treatment solution is dried at a low temperature and for a short
period of time.
[0059] Hereinafter, the present invention will be explained in detail with
reference to
Examples, which however shall not be construed as limiting the scope of the
invention
thereto.
Examples
[0060] [Production of Zinc-Based Plated Steel Sheet]
A steel strip of ultra-low carbon titanium-added steel having a sheet
thickness of
0.5 mm was used as the substrate steel to produce a hot-dip zinc alloy plated
steel sheet
having a zinc-based layer containing 6 mass % of aluminum, 3 mass % of
magnesium,
0.020 mass % of silicon, 0.020 mass % of titanium, and 0.0005 mass % of boron
(plating
deposition amount of 90 g/m2 per side), in a continuous hot-dip zinc plating
production line,
22
CA 3026697 2018-12-06
and the produced zinc alloy plated steel sheet was used as the original sheet
for chemical
treatment.
[0061] [Example 1]
A water-soluble molybdenum salt, a vanadium salt, an amine, a group 4A metal
oxoate, and a phosphate, which are shown in Table 1, were dissolved in water
to prepare
chemical treatment solutions 1 to 50. The name and symbol of each compound
added to
the chemical treatment solution are shown in Table 1. The composition and
color of each
chemical treatment solution are shown in Tables 2-1, 2-2, 3-1, 3-2, 4-1 and 4-
2. Note that
the dissolution of the vanadium salt was performed in an aqueous solution
having a liquid
temperature of 40 C or lower containing an amine for preventing vanadium from
being
reduced.
[0062]
23
CA 3026697 2018-12-06
a
w Table 1
ci
KJ
0, Type _Symbol Compound Name
Chemical Formula Molecular Weight
0,
l0
...1 Molybdate M1 Ammonium Molybdate
(NH4)6Mo7024.4H20 -
KJ
o VI Vanadium Pentoxide
V205 -
1-.
co Vanadium Salt V2 , Ammonium Metavanadate
NH4 V03
-
1
1-.
m
V3 Sodium Metavanadate
NaV03 -
1
0
-
0, EA Ethanolamine
C2H7NO 61
DEA Diethanolamine
C4HiiNO2 105
IPA 1-Amino-2-Propanol
C3H9NO 75
Amine TMAH Tetramethylammonium
hydroxide (CH3)4N+OH- 91
EDTA Ethylenediaminetetraacetic Acid
(HOOCCH2)2NCH2CH2N(CH2COOH)2 292
EN Ethylenediamine
NH2CH2CH2NH2 60
NH Aqueous Ammonia
NH4OH 35
Group 4A Oxoate Al Ammonium Zirconium Carbonate
(NH4)22r(OH)2(CO3)2
P1 Diammonium Hydrogen Phosphate
(NH4)211PO4 -
P2 Ammonium Dihydrogen Phosphate
NH4H2PO4 -
Phosphate P3 Triammonium Phosphate
(NH4)3P 04 -
-
P4 Phosphorous Acid
H3P03 -
P5 1-Hydroxyethane-1,1-Diphosphonic Acid
C21-1807P2 -
Fl Potassium Fluoride
KF -
Fluorine Compound F2 Ammonium Titanium Fluoride
(NH4)2TiF6 -
F3 Hydrofluosilicic Acid
H2SiF6 -
Si 3-Aminopropyltrimethoxysilane
H2NC3Fl6Si(OCH3)3 -
_
Silicon Compound S2 3-Glycidoxypropyltriethoxysilane
(112CCHO)CH20C31-I6Si(OC2H5) -3
S3 Vinylethoxysilane
H2C=CHSi(0C2115)3 -
24
0
w
0 [0063]
IQ
01
01 Table 2-1
1.0
.-1 Chemical Molybdate
Vanadium Salt Amine
m Treatment Mo -
V
0 Category
Conc.
1., Solution Compound Conc.
Compound Conc. Compound
co
(g/L)
1 No. (g/li)
, (g/I.)
1-,
m
1 Ex. 1 M1 , 0.075 V1
0.10 EA 0.036
0
0, Comp.Ex. 2 M1 0.019 V1
0.10 IPA 0.044
.
_
Ex. 3 M1 0.075 V2
0.01 EN 0.035
Ex. 4 M1 0.075 V2
0.10 NH 0.021
Comp.Ex. 5 M1 5.00 V3
0.10 EA 0.036
Ex. 6 M1 1.51 V3
2.00 IPA 0.883
_
Ex. 7 M1 0.075 V1
0.10 , EN 0.036
. _
Comp.Ex. 8 M1 0.075 V2
0.10 NH 0.007
.
_
Ex. 9 M1 24.0 V3
8.00 EN 15.1
. _
Comp.Ex. 10 M1 1.51 V1
8.00 NH 8.79
Comp.Ex. , 11 M1 0.015 V3
8.00 EA 15.3
Ex. 12 M1 0.075 V3
0.02 NH 0.027
Ex. 13 M1 24.0 V2
_ 8.00 EA 15.3
_
Ex. 14 _ M1 45.2 V3
8.00 IPA 18.8
_
Comp.Ex. 15 M1 90.4 V1
8.00 EN 15.1
_
_ _
Ex. 16 M1 24.0 V2
10.00 EA 19.2
_
Ex. 17 M1 _ 24.0 ,
V2 8.00 IPA 18.8
Comp.Ex. 18 M1 24.0 V3
, 8.00 EN 1.89
. _
Ex. 19 M1 22.6 V3
8.00 DEA 39.6
,
_
Ex. 20 M1 0.753 V3
0.80 EA 3.07
=
C)
w Table 2-2
0
ni Group 4A
01 Chemical Phosphate
0, Metal Oxoate
Color of
ko Treatment
MoN AmineN
-..3 Category Zr P
Treatment
Solution (Molar
Ratio) (Molar Ratio)
F')
o No. Compound Conc. Compound Conc.
Solution
1-,
co _ (i/L) (g1L)
1 _
r Ex. 1 Al _ 5.0 P1 0.25
0.40 0.30 Yellow
ro
I Comp.Ex. 2 Al 5.0 P2 0.25
0.10 0.30 Yellowish Green
0 _ _ _
01 Ex. 3 Al 5.0 P4 0.25
4.00 3.00 Yellow
_
Ex. 4 Al 5.0 P5 0.05
0.40 . 0.30 Yellow
_
Comp.Ex. 5 Al 5.0 P3 0.25
26.55 0.30 Yellowish Green
. . .
Ex. 6 _ Al 5.0 P3 0.25
0.40 0.30 Yellow
Ex. 7 Al 5.0 , P4 6.00
0.40 0.30 Yellow
Comp.Ex. 8 Al 5.0 P2 0.25
0.40 0.10 Yellowish Green
..
Ex. 9 Al 40.0 P1 20.0
1.59 L60 Yellow
Comp.Ex. 10 Al 40.0 P3 20.0 ,
0.10 1.60 Yellowish Green
. _
Comp.Ex. 11 Al 40.0 P2 20.0 _
0.00 L60 Yellowish Green
Ex. 12 Al 40.0 P5 20.0
1.59 1.60 Yellow
Ex. 13 Al 40.0 P4 2.00
1.59 1.60 Yellow
. _
Ex. 14 Al 40.0 P3 20.0 ,
3.00 1.60 Yellow
_
Comp.Ex. 15 Al 40.0 P2 20.0
6.00 L60 Yellowish Green
. . _ _
Ex. _ 16 Al 40.0 P1 20.0
1.27 1.60 Yellow
. _ . .
Ex. 17 Al 40.0 P5 60.0 _
1.59 1.60 Yellow _
Comp.Ex. 18 Al 40.0 P3 20.0
1.59 0.20 Yellowish Green
. . .
Ex. , 19 Al 40.0 . P1 20.0
1.50 2.40 Yellow
. .
Ex. 20 Al 40.0 P4 20.0
0.50 3.20 Yellow
26
,
(-)
w [0064]
0
n)
al Table 3-1
0,
to Chemical Molybdate Vanadium
Salt Amine
,4
Treatment Mo V iv
Category Conc.
0 Solution Compound Conc. Compound
Conc. Compound
1-,
WO
c No. (g/L)
(g/L)
1 .
1-,
A) Ex. 21 M1 24.0 V2
8.00 NH 8.79
1
co Ex. 22 M1 24.0 V2
8.00 EN 15.1
0,
Ex. 23 M1 24.0 V3
8.00 , TMAH 22.9
Ex. 24 M1 14.1 V2
5.00 NH 11.0
. _
Ex. 25 M1 1.98 V3
0.30 EA 1.15
Ex. 26 M1 0.075 V1
0.10 EN 0.036
Ex. 27 M1 24.0 V3
8.00 EDTA 73.4
Ex. 28 M1 25.4 V2
3.00 NH 1.65
Ex. 29 M1 0.942 V2
1.00 NH 1.10
Ex. 30 M1 6.59 VI
1.00 IPA 5.89
Ex. 31 M1 3.50 . V2
2.00 NH 2.20
Ex. 32 M1 _ 0.075 _ V1
0.10 EDTA 0.172
Ex. 33 M1 1.41 V3
0.50 IPA 1.77
Ex. 34 M1 0.075 V2
0.10 NH 0.021
Ex. 35 M1 3.77 V3
0.80 IPA 3.77
_
_
Ex. 36 M1 24.0 V2
8.00 NH 8.79
,
Ex. 37 M1 3.50 _ V1
2.00 IPA 4.71
Ex. 38 M1 0.075 . V3
0.10 EA 0.036
Ex. 39 M1 . 3.11 V3
0.30 IPA 1.06
Ex. 40 M1 7.53 V2
8.00 EN 22.6
27
a
w
o Table 3-2
m
ch Group 4A
ch Chemical Phosphate
to Metal Oxoate
Color of
...1 Treatment
Mo/V Amine/V
N Category Zr
P Treatment
0 Solution
(Molar Ratio) (Molar Ratio)
I-. No. Compound Conc.
Compound Conc. .. Solution
co
1 (g/L) (WO
1-.
N Ex. 21 Al 40.0 P2
0.50 1.59 1.60 Yellow
1
0 Ex. 22 Al 5.0 P4 0.25
1.59 1.60 Yellow
0,
Ex. 23 Al 40.0 P1 20.0
1.59 1.60 Yellow
Ex. 24 Al 33.5 P5 0.60
1.50 3.20 Yellow
Ex. 25 Al 5.0 P3 0.25
3.50 3.20 Yellow
Ex. 26 Al 14.0 , P4 6.00
0.40 0.30 Yellow
Ex. 27 Al 40.0 P1 20.0
1.59 1.60 Yellow
Ex. 28 Al , 27.0 P2 0.50
4.50 0.80 Yellow
Ex. 29 Al , 46.5 P2 0.50
0.50 1.60 Yellow
_
Ex. 30 Al , 5.0 P2 0.25
3.50 4.00 Yellow
Ex. 31 Al 7.5 P2 , 0.50
0.93 1.60 Yellow
Ex. 32 Al 5.0 P1 0.25
0.40 0.30 Yellow
_
Ex. 33 Al 40.0 P3 0.50
1.50 2.40 Yellow
Ex. 34 Al 40.0 P2 0.50
0.40 0.30 Yellow
Ex. 35 Al 5.0 P3 0.25
2.50 3.20 Yellow
Ex. 36 Al 33.5 P2 0.50
1.59 16.0 Yellow
Ex. 37 Al 14.0 P2 0.50
0.93 1.60 Yellow
Ex. 38 Al 33.5 P3 , 0.50
0.40 0.30 Yellow
Ex. 39 Al ... 40.0 P4
20.0 5.50 2.40 Yellow
_
Ex. _ 40 Al 20.5 P4 0.50
0.50 2.40 Yellow .
28
=
C)
[0065]
to
o Table 4-1
it)
0, Chemical Molybdate Vanadium
Salt Amine
0,
to Treatment Mo
V
=-.1
Category Conc.
IQ Solution Compound Conc. Compound
Conc. Compound
0 No. _ (g/L)
(g/L) , (g/L)
1-.
03
,
.. Ex. 41 M1 24.0 V3 8.00
EN 15.1
1 .
1-. - 4_
KJ Ex. 42 M1 0.075 V3
_ 0.10 NH 0.021
1 _
0 _ Ex. 43 MI 0.471 V1
, 0.50 DEA 4.12
0, _
Ex. 44 M1 . 24.0 V2 8.00
NH 8.79
Ex. 45 M1 23.5 V2 5.00 ,
IPA 29.4
_
Ex. 46 M1 24.0 V2 8.00
NH 8.79
Ex. 47 M1 , 0.075 V3 0.10
IPA 0.044
..,
Ex. 48 M1 0.075 V2 , 0.10
IPA 0.044
-r
Ex. 49 M1 , 0.075 V1 0.10
TMAH 0.054
_
_
Ex. 50 M1 14.1 V1 3.00
EN 5.75
29
r)
4) Table 4-2
0
n)
01 Group 4A
Phosphate
Color of
a', Chemical
kc) Metal Oxoate
-I Treatment =
Mo(V AminelV
Category Zr P
Treatment
N Solution (Molar
Ratio) (Molar Ratio)
0
No. Compound Conc.
Compound Conc. Solution
co (WO . _
(g/L)
I .
1-, -
n) Ex. 41 Al 40.0 P5 20.0
1.59 1.60 Yellow
_ ' -
1 _
0 Ex. 42 Al 40.0 P2 20.0
0.40 0.30 Yellow
0, ..,.. L_
Ex. 43 Al 5.0 P1 0.25
0.50 4.00 Yellow
.,_ _
Ex. 44 Al , 46.5 P2 0.50
1.59 1.60 Yellow
_
Ex. 45 Al _ _ 27.0 P1 , 7.50
2.50 4.00 , Yellow
.
Ex. 46 Al 5.0 P5 0.25
1.59 1.60 Yellow
_
Ex. 47 Al 40.0 P3 20.0
0.40 0.30 Yellow
_
Ex. 48 Al 27.0 P5 _ 7.50
0.40 0.30 , Yellow
,
Ex. 49 Al 5.0 P1 0.25
0.40 0.30 Yellow
..
Ex. 50 Al 7.5 P4 6.00
2.50 1.60 Yellow
[0066] The surface of the original sheet for chemical treatment was degreased,
and dried.
Then, each of chemical treatment solutions Nos. 1 to 18 shown in Table 2-1 was
applied to
the surface of the original sheet for chemical treatment, and immediately
thereafter heated
= and dried at a low temperature (a temperature of the steel strip of 40 or
80 C) using an
automatic discharge type electric hot air oven to form a chemical conversion
film. Thus,
chemically treated steel sheets Nos. 1 to 36 having the chemical conversion
film were
produced. Note that the deposition amount of the chemical conversion film in
all the
chemically treated steel sheets was set at 200 mg/1m2
.
[0067] [Evaluation of Chemically Treated Steel Sheet]
For a test specimen cut out from each chemically treated steel sheet, the
structure
of the chemical conversion film was identified; the percentage of pentavalent
vanadium
based on mixed-valent vanadium in the film was determined; the film deposition
amount
was measured; and the test specimen was subjected to corrosion resistance test
and
blackening resistance test.
[0068] (1) Identification of Structure of Chemical Conversion Film
The structure of the chemical conversion film was identified using the
above-mentioned TEM, EDS, and XPS.
[0069] For example, FIG 1 is a TEM image of the cross-section of a test
specimen of
chemically treated steel sheet No. 17. As illustrated in FIG I, the chemical
conversion
film of chemically treated steel sheet has a two-layer structure including the
first chemical
conversion layer and the second chemical conversion layer.
[0070] FIG 2 shows an element distribution of the test specimen of chemically
treated
steel sheet No. 17, from the surface thereof toward the depth direction,
measured using
GDS. The abscissa in FIG 2 indicates a measuring time (corresponding to the
depth from
the surface), and the ordinate indicates the relative intensity. As shown in
FIG 2, in the
chemical conversion film of chemically treated steel sheet No. 17, the first
chemical
31
CA 3026697 2018-12-06
conversion layer contains large amounts of molybdenum, vanadium, and
phosphorus, and
the second conversion layer contains zirconium.
[0071] Although not specifically illustrated, it was also confirmed, in other
chemically
treated steel sheet categorized in Examples, that the chemical conversion film
has the
two-layer structure in the same manner as chemically treated steel sheet No.
17, and
contains vanadium, molybdenum, and phosphorus in the first chemical conversion
layer
and a group 4A metal oxoate in the second chemical conversion layer. The two-
layer
structure in the chemical conversion film was not confirmed in chemically
treated steel
sheets categorized in Comparative Examples.
[0072] (2) Measurement of Deposition Amount of Chemical Conversion Film
For the confirmation of the deposition amount, zirconium in the film was
measured using a fluorescent X-ray apparatus, and the measurement was used as
an index
the deposition amount.
[0073] (3) Measurement of Percentage of Pentavalent Vanadium based on Mixed-
valent
Vanadium in Chemical Conversion Film
The percentage of pentavalent vanadium based on mixed-valent vanadium (V5+/V)
in the chemical conversion film was determined by analyzing the chemical
binding state of
vanadium in the chemical conversion film using X-ray Photoelectron
Spectroscopy (XPS).
Two points of the surface layer of the chemical conversion film and the
interface between
the chemical conversion film and the plating layer were taken as points for
analysis for
each site of 10 locations randomly selected from the above-mentioned test
specimen. The
analysis of the interface between the chemical conversion film and the plating
layer was
performed after the chemical conversion film was sputtered using an argon beam
from the
surface layer. The depth at which the chemical conversion film was sputtered
was
determined by measuring the thickness of the chemical conversion film from the
results of
observation of the film cross-section using TEM. The percentage of pentavalent
32
CA 3026697 2018-12-06
vanadium based on mixed-valent vanadium was determined from the percentage of
a peak
area of about 516.5 eV derived from V" (Sys) based on the total sum of the
peak area
derived from V' and a peak area of 514 eV derived from V' (Sv4) (Sv5/(Sv4
Sys). The
= average value of the percentages at 10 measuring locations in each test
specimen was
employed as the percentage of pentavalent vanadium based on mixed-valent
vanadium
(V5W) in the chemically treated steel sheet.
[0074] For example, FIG 3 is an intensity profile of chemical binding energy
corresponding to 2p orbit of vanadium in a film/plating layer interface in one
location of 10
measuring locations at which a test specimen of chemically treated steel sheet
No. 12
produced by drying chemical treatment solution No. 4 at a drying temperature
of 80 C was
measured. The abscissa in FIG 3 indicates binding energy, and the ordinate
indicates
relative intensity for a short period of time (per second). Further, solid
line Mv in FIG 3
is an intensity profile of chemical binding energy actually measured in the
measuring point.
Dotted line Pv5 indicates a peak derived from pentavalent vanadium, dotted
line Pv4
indicates a peak derived from tetravalent vanadium, and solid line B indicates
a baseline.
[0075] It could be confirmed, from FIG. 3, that the percentage of V5+ in the
chemical
conversion film was 0.7 or more in the above-mentioned test specimen. It was
confirmed
that the percentage of V5+ in the chemical conversion film was 0.7 or more
also in other
chemically treated steel sheets, although not particularly illustrated.
[0076] (4) Flat Part Corrosion Resistance Test
The edge surface of the test specimen of each chemically treated steel sheet
was
sealed and subjected to a salt spray test for 120 hours in accordance with JIS
Z2371, and
thereafter white rust generated on a surface of the test specimen was
observed. Each
chemically treated steel sheet was evaluated as follows: when the percentage
of an area
where white rust was generated was 5% or less, the evaluation was "A"; when
the
percentage was more than 5% to 10% or less, the evaluation was "B"; when the
percentage
33
CA 3026697 2018-12-06
was more than 10% to less than 30%, the evaluation was "C"; and when the
percentage
was 30% or more, the evaluation was "D."
[0077] (5) Worked Part Corrosion Resistance Test
= A bead drawing test (bead height: 4 mm, pressure: 1.0 kN) was performed
for a
test specimen of 30 mm x 250 mm of each chemically treated steel sheet, and
the edge
surface of the test specimen was sealed and subjected to a salt spray test for
24 hours in
accordance with JIS Z2371; thereafter white rust generated on a sliding
surface was
observed. Each chemically treated steel sheet was evaluated as follows: when
the
percentage of an area where white rust was generated was 5% or less, the
evaluation was
"A"; when the percentage was more than 5% to 10% or less, the evaluation was
"B"; when
the percentage was more than 10% to less than 30%, the evaluation was "C"; and
when the
percentage was 30% or more, the evaluation was "D."
[0078] (6) Blackening Resistance Test
A test specimen of each chemically treated steel sheet was left to stand for a
predetermined time in a humid atmosphere (temperature 60 C, humidity 90%RH),
and
thereafter the brightnesses of the test specimen before and after the test
were compared.
The brightness (L value) of the test specimen was measured using a
spectroscopic
color-difference meter (TC-1800; Tokyo Denshoku Co., Ltd.). Each chemically
treated
steel sheet was evaluated as follows: when brightness difference AL was 3.0 or
less, the
evaluation was "A"; when the brightness difference AL was more than 3.0 to 6.0
or less,
the evaluation was "B"; when the brightness difference AL was more than 6.0 to
less than
10.0, the evaluation was "C"; and when the brightness difference AL was 10.0
or more, the
evaluation was "D."
[0079] (7) Evaluation Results
The chemical treatment solutions used, the ratio of each element in the
chemical
conversion film, the results of the corrosion resistance test, and the results
of the
34
CA 3026697 2018-12-06
blackening resistance test for each chemically treated steel sheet are shown
in Tables 5-1,
5-2, 6-1, and 6-2. Note that, in the following tables, the ratio of each
element in the
chemical conversion film is represented as parts by mass of each element based
on 100
parts by mass of zirconium.
CA 3026697 2018-12-06
'
o
w [0080]
0
n)
al Table 5-1
,
01
l0
Ratio of Each Element
...]
in Chemical Conversion Film
IN) Chemically Treated Chemical Film
Drying
0
(Parts by Mass)
1-, Category Steel Sheet Treatment Solution
Deposition Amount Temperature
co
1
1-, No. No. (mg/m2)
( C)
r,)
Mo V P
1
0
'
0,
Ex. 1 1 200
40 1.5 2.0 5.0
-
Comp. Ex. 2 2 200 40 0.4
2.0 5.0
-
Ex. 3 3 - 200
40 1.5 0.2 5.0
-
Ex. 4 4 200
40 1.5 2.0 1.0
_
Comp. Ex. 5 5 200 40
100.0 2.0 5.0
-
Ex. 6 6 200
40 30.1 40.0 5.0
Ex. 7 7 200
40 1.5 2.0 120.0
_
Comp. Ex. _ 8 8 200 40
1.5 2.0 5.0
Ex. 9 1 200
80 , 1.5 s 2.0 5.0
. -
Comp. Ex. 10 2 200 80 0.4
. 2.0 5.0
Ex. 11 3 200 _
80 , 1.5 , 0.2 5.0
Ex. , 12 4 200
80 1.5 2.0 1.0
..
-
Comp. Ex. 13 5 200 80
100.0 2.0 5.0
- -
Ex. 14 6 200 -
80 30.1 40.0 5.0
-
Ex. _ 15 7 200
- 80 1.5 2.0 . 120.0
Comp. Ex. 16 8 200 80 1.5
2.0 5.0
36
'
(-)
D.,
w
0 Table 5-2
m
ch
ch Chemically Treated Chemical
Evaluation Results
l0
-,1 Category Steel Sheet Treatment Solution V5+.
Corrosion Resistance Blackening
m No. No. Percentage
Flat Part Worked Part Resistance
0
'-` Ex. 1 1 0.92
A A A
CO
I
Comp. Ex. 2 2 0.40
D D D
r.)
1 Ex. 3 3 0.88
B B B
0 ,
ch Ex. 4 4 0.79
B B A
Comp. Ex. 5 5 045
C D D
Ex. 6 6 0.95
A B A
,
Ex. 7 7 0.75
B B A
Comp. Ex. , 8 8 0.40
C C D
Ex. 9 1 0.95
A A A
Comp. Ex. 10 2 0.41
D D D
Ex. 11 3 0.91
B B B
Ex. 12 4 0.81
B B A
Comp. Ex. 13 5 0.46
C D D
Ex. 14 6 0.98
A B A
Ex. 15 7 0.77 _
B B A
Comp. Ex. 16 8 0.41
C C D
37
o
w
0 [0081]
n)
al
01
to Table 6-1
,4
Ratio of Each Element
iv
0
Chemically Treated Chemical Film
Drying in Chemically Treated Film
co Category Steel Sheet Treatment Solution Deposition
Amount Temperature . (Parts by Mass)
1
1-,
F') No. No. (mg/m2)
( C)
Mo V P
1
.0
0, ..
_
Ex. 17 9 200
40 60.0 20.0 50.0
_
_
Comp. Ex. 18 10 200
40 3.8 20.0 50.0
_
_
Comp. Ex. 19 11 200
40 0.0 20.0 50.0
.
_
Ex. 20 12 200
40 0.2 0.1 50.0
_
_
Ex. 21 _ 13 200
40 _ 60.0 20.0 5.0
Ex. 22 14 200
40 113.0 20.0 50.0
.
_
Comp. Ex. 23 15 200
40 226.0 20.0 50.0
Ex. 24 16 200
40 60.0 25.0 50.0
_
-
Ex. 25 17 200
40 60.0 20.0 150.0
.
_
Comp. Ex. 26 18 200
40 60.0 20.0 50.0
.
.
Ex. 27 9 200
80 60.0 20.0 50.0
_
Comp. Ex. 28 10 . 200
80 3.8 20.0 50.0
'
_
Comp. Ex. 29 11 200
80 0.0 20.0 50.0
Ex. 30 12 200
80 0.2 0.1 50.0
_
Ex. 31 13 200
80 _ 60.0 20.0 5.0
Ex. 32 14 200
80 . 113.0 20.0 50.0
_
Comp. Ex. 33 15 200
80 226.0 20.0 50.0
Ex. 34 16 200
80 60.0 25.0 50.0
_
_
Ex. 35 17 200
80 60.0 20.0 150.0
Comp. Ex. 36 18 200
80 60.0 20.0 50.0
38
=
C)
w Table 6-2
0
A)
Evaluation Results
01 Chemically Treated Chemical
_
01
Corrosion
to Category Steel Sheet Treatment Solution V5+
Blackening
-.1
Resistance
A) No. No. Percentage -
Resistance
o
Flat Part Worked Part
1-, .
co Ex. 17 9 0.92
A A A
1
1- Comp. Ex. 18 10 0.43
C C D
IS.)
,
1
o Comp. Ex. 19 11
0.35 C C D
01
Ex. 20 12 0.95
B B B
Ex. 21 13 0.92
B B A
Ex. 22 14 0.86
A B A
Comp. Ex. 23 15 _ 0.25 C D
D
Ex. 24 16 0.85
A B A
Ex. 25 17 0.90
B B A
_
Comp. Ex. 26 18 0.32 C C
D
Ex. 27 9 0.95
A A A
.
_
Comp. Ex. 28 10 0.44 C C
D
Comp. Ex. 29 11 _ 0.36 C C
D
Ex. 30 12 0.98
B B B
_
Ex. 31 13 0.95
B B A
_
Ex. 32 14 0.89
B D B
_
Comp. Ex. 33 15 0.26 C D
D
Ex. 34 16 0.88
A B A
,
Ex. 35 17 0.93
B B A
_
Comp. Ex. 36 18 0.33 C C
D
39
[0082] As is obvious from Tables 5-1, 5-2, 6-1, and 6-2, chemically treated
steel sheets
each having a chemical conversion film in which the percentage of pentavalent
vanadium
based on mixed-valent vanadium in the chemical conversion film is 0.7 or more,
and which
includes a first chemical conversion layer containing vanadium, molybdenum and
phosphorus, and a second chemical conversion layer disposed on the first
chemical
conversion layer and containing a group 4A metal oxoate, the chemical
conversion film
being disposed on the surface of a zinc-based plated steel sheet having a zinc-
based plating
layer containing 0.1 to 22.0 mass % of aluminum have favorable corrosion
resistance and
blackening resistance. The chemical conversion film is obtained by applying a
chemical
treatment solution which contains a water-soluble molybdate, a vanadium salt,
an amine, a
group 4A metal oxoate, and a phosphate, in which the molar ratio of molybdenum
to
vanadium is 0.4 to 5.5, and the molar ratio of an amine to vanadium is 0.3 or
more to the
zinc-based plated steel sheet, followed by drying. The favorable corrosion
resistance and
blackening resistance of the chemically treated steel sheets are obtained even
when the
chemical treatment solution applied to the plated steel sheet is dried at a
relatively low
drying temperature of 40 C or 80 C.
[0083] In addition, as is obvious from Tables 5-1, 5-2, 6-1, and 6-2, when the
percentage
of pentavalent vanadium in the chemical conversion film is 0.7 or less,
corrosion resistance
and blackening resistance are inferior.
[0084] [Example 2]
Next, chemically treated steel sheets Nos. 37 to 100 were produced in the same
manner as chemical treated steel sheet No. 1 except that the type and the
deposition amount
of the chemical treatment solutions were changed as shown in the following
tables, and
were evaluated in the same manner as chemically treated steel sheets Nos. 1 to
36. The
results are shown in the following Tables 7-1, 7-2, 8-1, 8-2, 9-1, 9-2, 10-1,
and 10-2.
CA 3026697 2018-12-06
.
-
a
[0085]
CO
0
" Table 7-1
ch
cn
ko
Ratio of Each Element
...1
in Chemically Treated Film
r..) Chemically Treated Chemical Film
Drying0 (Parts by Mass)
1-. Category Steel Sheet Treatment Solution Deposition Amount
Temperature
co
1
No. No. (mg/m2)
(C)
H
Mo V P
I'.)
1
0
0, Ex. _ 37 19 200
40 56.5 20.0 50.0
Ex. 38 20 500
40 1.9 _ 2.0 50.0
Ex. , 39 21 500
40 60.0 20.0 1.3
- .
. Ex. , 40 22 100
40 , 480.0 160.0 5.0
_ _
Ex. , 41 23 300
40 60.0 20.0 50.0
. . _
Ex. 42 24 1000
40 42.2 14.9 1.8
. .
Ex. 43 25 500
40 39.6 6.0 5.0
_
Ex. 44 26 400
_ . .
40 0.5 0.7 42.9
_
Ex. 45 - 27 250
40 60.0 20.0 , 50.0
_
Ex. 46 28 100
40 94.2 11.1 1.9
. _ _
Ex. 47 29 150
40 2.0 2.2 1.1
. _
Ex. 48 30 50
40 131.8 20.0 5.0
_ .
Ex. 49 31 100
40 46.7 26.7 6.7
. _
Ex. _ 50 32 400
40 1.5 2.0 5.0
_ .
Ex. 51 _ 33 250
40 3.5 1.3 1.3
. . ..
Ex. 52 34 10000
40 0.2 0.3 1.3
41
(-)
D.,
w
o Table 7-2
I'.)
0, Chemically Treated Chemical
Evaluation Results
0,
li) Category Steel Sheet Treatment Solution V5+
Corrosion Resistance Blackening
,..,
n) No. No. Percentage
Flat Part Worked Part Resistance
0
P Ex. 37 19 0.87
B B A
co
1 1-. Ex. 38 20 0.93
A A A . n) Ex. 39 21 0.96 B B A
1
o
0, Ex. 40 22 0.92
B B A
_
Ex. 41 23 0.91
B B A
_
Ex. 42 24 0.89
A B A
_
Ex. 43 25 0.85
B A A
Ex. 44 26 0.93
B B B
Ex. 45 27 0.76
B B A
Ex. 46 28 0.79
B B A
Ex. 47 29 0.91
B A A
Ex. 48 30 0.86
A B A
Ex. 49 . 31 0.98
B A A
Ex. 50 32 0.86
B B A
_
Ex. 51 33 ' 0.70
A B A
Ex. 52 34 0.95
B A B
42
C)
co
o [0086]
it)
0,
0) Table 8-1
to
=-.1 Ratio of Each Element
it)
0
in Chemically Treated Film
1-. Chemically Treated Chemical Film
Drying
co
(Parts by Mass)
Category Steel Sheet Treatment Solution Deposition
Amount Temperature
1
1-.
iv No. No. (mg/m2)
( C)
1
Mo V P
0
0, Ex. 53 - 35 1000
40 75.3 16.0 5.0
Ex. 54 36 300
40 71.6 23.9 1.5
Ex. 55 37 300
40 25.0 14.3 3.6
Ex. 56 38 150
40 0.2 0.3 1.5
_
Ex. 57 39 1000
40 7.8 0.8 50.0
Ex. 58 40 500
40 36.7 39.0 2.4
Ex. 59 41 100
40 60.0 20.0 50.0
_
Ex. 60 42 300
40 0.2 0.3 50.0
Ex. 61 43 150
40 9.4 10.0 5.0
Ex. 62 44 50
40 51.6 17.2 1.1
Ex. 63 45 200
40 , 87.2 18.5 27.8
Ex. 64 46 300
40 480.0 160.0 5.0
Ex. 65 47 50
40 0.2 0.3 50.0
Ex. _ 66 48 200
40 0.3 0.4 27.8
Ex. 67 49 250
40 1.5 2.0 5.0
Ex. , 68 50 50
40 188.3 40.0 80.0
43
C)
Table 8-2
(.0 _
0 Chemically Treated Chemical
Evaluation Results
m .
0, Category Steel Sheet Treatment Solution V6+
Corrosion Resistance Blackening
01
k0 No. No. Percentage
Flat Part Worked Part Resistance
..] .
IQ Ex. 53 35 0.83
A B A
_ .
0
_
1-. Ex. 54 36 0.79
A B A
I
1-. Ex. 55 37 0.75
B J A A
,
IQ
1 Ex. 56 38 0.78
A A B
0
01 Ex. 57 39 0.71
B A B
_
Ex. 58 40 0.93
A B A
_
_ _
. .
Ex. 59 41 0.85
A A A
..
Ex. . 60 42 0.98
B A B
_
Ex. 61 . 43 0.85
B B A
Ex. 62 44 0.79
A B A
. .
Ex. . _ 63 45 0.99
A A A
_
Ex. 64 46 0.97
B B A
. _
.
- . .
Ex. _ 65 47 0.90
B A B
, _
Ex. 66 . 48 0.73
B A B
- .
Ex. 67 49 0.86
B B A
, _
_
Ex. 68 50 0.71
B B . A
44
=
= "
(-)
w
o [0087]
n)
al
01 Table 9-1
l0
...]
Ratio of Each Element
IN
o in Chemically Treated Film
1-, Chemically Treated Chemical Film
Drying
co
(Parts by Mass)
Category Steel Sheet Treatment Solution Deposition
Amount Temperature
1
1-,
r,) No. No. (mg/m2)
( C)
Mo V P
1
0
0,
Ex. 69 19 200 80
56.5 20.0 50.0
_
Ex. 70 20 500 80
1.9 2.0 50.0
Ex. 71 21 500 80
60.0 20.0 1.3
Ex. 72 22 100 80
480.0 160.0 5.0
. .
Ex. 73 23 300 80
60.0 20.0 50.0
_
Ex. 74 24 1000 80
42.2 14.9 1.8
Ex. _ 75 25 500 80
39.6 6.0 5.0
_ Ex. 76 26 400 80
0.5 _ 0.7 42.9
Ex. 77 27 250 80
60.0 20.0 50.0
. _
Ex. 78 28 100
80 , 94.2 11.1 L9
Ex. 79 29 150 80
2.0 2.2 1.1
Ex. 80 30 50 80
131.8 20.0 5.0
_
Ex. 81 31 100 80
46.7 26.7 6.7
Ex. 82 32 400 80
1.5 2.0 5.0
Ex. .. 83 33 250 80
3.5 1.3 1.3
Ex. 84 34 10000 80
0.2 0.3 1.3
\
. 45
P Table 9-2
ui
0 Chemically Treated Chemical
Evaluation Results
t..)
.
ril Category Steel Sheet Treatment Solution VS+
Corrosion Resistance Blackening
ril
l0 No. No. Percentage
Flat Part Worked Part Resistance
-.1 .
1.) Ex. 69 19 0.87
B B A
0 . . 1-, A A
A Ex. 70 20 0.93
co .
1
1-` Ex. 71 21 0.73
B B A
. .
Iv
1 Ex. 72 22 0.86
B B A
0 ,
.
ril Ex. 73 23 0.73
B B A
Ex. 74 24 0.73
A B A
Ex. 75 25 0.89
B A A
Ex. 76 26 0.72 _
B B B
_
Ex. 77 27 0.75 _
B
B A
Ex. 78 28 0.81
B B A
_ _
Ex. 79 29 0.75
B A A
¨
Ex. 80 30 0.84
A B A
Ex. 81 31 0.77
B A A
_ ..
Ex. 82 32 0.81
B B A
Ex, 83 33 _ 0.92
A B A
-
Ex. 84 34 0.72
B A B
46
0
W NO 8 8 ]
0
IQ
CA
cs Table 10-1
to
^-1
Ratio of Each Element
IQ
in Chemically Treated Film
o Chemically Treated Chemical Film
Drying
P
(Parts by Mass)
co Category Steel Sheet Treatment Solution Deposition
Amount Temperature
1
I.,
IQ No. No. (mg/m2)
( C)
O
Mo V P
(3) .
Ex. 85 35 1000 80
75.3 16.0 5.0
Ex. 86 36 300 80
7L6 23.9 1.5
Ex. , 87 37 300 80
25.0 14.3 3.6
Ex. 88 38 150 80
0.2 0.3 1.5
Ex. 89 39 1000 80 , 7.8
0.8 50.0
. =
Ex. 90 40 500 80
, 36.7 39.0 2.4
Ex. 91 41 100 80
_ 60.0 20.0 50.0
Ex. 92 42 300 80
0.2 0.3 50.0
Ex. 93 43 150 80 _ 9.4
10.0 5.0
Ex. 94 44 50 80
_ 51.6 17.2 1.1
Ex. 95 45 200 80
87.2 18.5 27.8
.
_
Ex. 96 46 300 80
480.0 160.0 5.0
_
Ex. 97 47 50 80
0.2 0.3 50.0
-
..
Ex. 98 48 200 80 _ 0.3
0.4 27.8
Ex. 99 49 250 80
1.5 2.0 5.0
_
Ex. 100 50 50 80
188.3 40.0 80.0
47
'
=
0
D.,
w Table 10-2
0
r.)
(3) Chemically Treated Chemical
Evaluation Results
(3)
li) Category Steel Sheet Treatment Solution 175+
Corrosion Resistance Blackening
,..,
No. No. Percentage
Flat Part , Worked Part Resistance
m .
0 Ex. , 85 35 0.90
A B A
P
CO Ex. 86 _
_
1 36 0.71
A B A
1-.
m Ex. 87 . 37 0.89
B A A
1 .
0 Ex. 88 _ 38 0.97
A A B
Ex. 89 39 0.82
B A B
_ .
Ex. 90 _ 40 0.77
A B A
Ex. 91 41 0.90
A A A
Ex. 92 42 0.86
B A B
Ex. 93 43 0.70
B B A
Ex. 94 44 0.98
A B A
_ _
Ex. 95 45 0.98
A A A
_
Ex. 96 46 0.79
B B A
_ _ .
Ex. 97 47 0.95
B A B
_
Ex. 98 48 0.81
B A B
Ex. 99 49 0.90
B B A
Ex. 100 50 0.79
B B A
48
[0089] As is obvious from Tables 7-1, 7-2, 8-1, 8-2, 9-1, 9-2, 10-1, and 10-2,
chemically
treated steel sheets each having a chemical conversion film in which the
percentage of
pentavalent vanadium based on mixed-valent vanadium in the chemical conversion
film is
0.7 or more, and which includes a first chemical conversion layer containing
vanadium,
molybdenum and phosphorus, and a second chemical conversion layer disposed on
the first
chemical conversion layer and containing a group 4A metal oxoate, the chemical
conversion film being disposed on the surface of a zinc-based plated steel
sheet having a
zinc-based plating layer containing 0.1 to 22.0 mass % of aluminum have
favorable
corrosion resistance and blackening resistance in a wide range of the
deposition amount of
the chemical conversion film. The chemical conversion film is obtained by
applying a
chemical treatment solution which contains a water-soluble molybdate, a
vanadium salt, an
amine, a group 4A metal oxoate, and a phosphate, in which the molar ratio of
molybdenum
to vanadium is 0.4 to 5.5, and the molar ratio of an amine to vanadium is 0.3
or more to the
zinc-based plated steel sheet, followed by drying. The favorable corrosion
resistance and
blackening resistance of the chemically treated steel sheets are obtained,
regardless of the
deposition amount of the chemical conversion film, even when the chemical
treatment
solution applied to the plated steel sheet is dried at a relatively low drying
temperature of
40 or 80 C.
[0090] Next, chemically treated steel sheets Nos. 101 to 106 which were
comparative
materials were prepared in the same manner as chemical treated steel sheet No.
1 except
that the chemical treatment solutions were respectively changed to prior arts
A to C, and
were evaluated in the same manner as Example 1 according to the above-
mentioned
evaluation criteria. The results are shown in the following Tables 11-1 and 11-
2.
[0091] [Prior Art A]
Commercially available partially reduced chromate treatment solution (ZM-3387;
Nihon Parkerizing Co., Ltd.) was applied to the surface of an original sheet
for chemical
49
CA 3026697 2018-12-06
treatment, and immediately thereafter heated and dried at a low temperature (a
temperature
of the steel strip of 40 or 80 C) using an automatic discharge type electric
hot air oven to
form a chemical conversion film. Note that the chrome deposition amount of the
chemical conversion film was 200 mg/m2.
[0092] [Prior Art B]
A blue transparent chemical treatment solution to which ammonium zirconium
carbonate, vanadyl tartrate, phosphoric acid and citric acid were added was
applied to the
surface of an original sheet for chemical treatment, and immediately
thereafter heated and
dried at a low temperature (a temperature of the steel strip of 40 or 80 C)
using an
.. automatic discharge type electric hot air oven to form a chemical
conversion film. The
vanadyl tartrate was prepared by reducing vanadium pentoxide in an aqueous
tartaric acid
solution. Note that the zirconium deposition amount and the vanadium
deposition amount
of the chemical conversion film were both 200 mg,/m2.
[0093] [Prior Art C]
A colorless transparent chemical treatment solution to which titanium
hydrofluoric
acid and phosphoric acid were added was applied to the surface of an original
sheet for
chemical treatment, and immediately thereafter heated and dried at a low
temperature (a
temperature Of the steel strip of 40 or 80 C) using an automatic discharge
type electric hot
air oven to form a chemical conversion film. Note that the titanium deposition
amount of
.. the chemical conversion film was 200 mg/m2.
CA 3026697 2018-12-06
C)
w
0 [0094]
m
01
01
to Table 11-1
,..,
Ratio of Each Element
tv
0
in Chemically Treated Film
1-, Chemically Treated Chemical Film,
Drying
co(Parts by Mass)
1 Category Steel Sheet
Treatment Solution Deposition Amount Temperature
i-
m No. No. (mg/m2)
( C)
o1
Mo V P
ol
Comp. Ex. 101 Prior Art A 200
40 - -
-
...
Comp. Ex. 102 Prior Art A 200
80 - - -
-
-
Comp. Ex. 103 Prior Art B 200
40 -
Comp. Ex. 104 Prior Art B 200
80 - - -
-
Comp. Ex. 105 Prior Art C 200
40 - .
_ .
Comp. Ex. 106 Prior Art C 200
80 - - -
Table 11-2
Chemically Treated Chemical Evaluation Results
Category Steel Sheet Treatment Solution V5+
Corrosion Resistance Blackening
No. No. Percentage Flat Part
Worked Part Resistance
Comp. Ex. 101 ' Prior Art A . -
C D A
_
Comp. Ex. 102 Prior Art A -
C D A
-
Comp. Ex. 103 Prior Art B -
D D D
Comp. Ex. 104 Prior Art B . -
C D D
Comp. Ex. 105 Prior Art C -
D D D
Comp. Ex. 106 Prior Art C -
C D D
51
[0095] The chemically treated steel sheets Nos. 101 and 102 obtained by using
the
commercially available chromate treatment solution were inferior in flat part
corrosion
resistance and worked part corrosion resistance, since the chemical treatment
solution was
dried at a low temperature. Further, the chemically treated steel sheets Nos.
103 to 106
obtained by using the chemical treatment solution in which vanadium was
reduced with the
addition of an organic acid or the chemical treatment solution containing a
fluoride were
each markedly inferior in flat part corrosion resistance, worked part
corrosion resistance
and blackening resistance, since the chemical treatment solutions were dried
at a low
temperature.
[0096] As described above, it can be found, from the comparison between the
test results
of prior arts shown in Tables 11-1, 11-2 and Examples shown in Tables 5-1, 5-
2, 6-1, 6-2,
7-1, 7-2, 8-1, 8-2, 9-1, 9-2, 10-1, 10-2, that the chemically treated steel
sheet according to
the present invention has favorable corrosion resistance and blackening
resistance
compared to that of the prior arts. Further, it can be found that the
chemically treated
steel sheet is obtained by the production of a chemical conversion film made
from the
chemical treatment solution according to the present invention. Furthermore,
it can be
found that the favorable corrosion resistance and blackening resistance are
also obtained by
drying the chemical treatment solution at a low temperature.
[0097] [Example 3]
A chemically treated steel sheet produced according to the following procedure
was provided. For an original sheet for chemical treatment, a steel strip of
ultra-low
carbon titanium-added steel having a sheet thickness of 0.5 mm was used as the
substrate
steel to produce a hot-dip zinc plated steel sheet of having a zinc-based
layer containing
0.018 mass % of aluminum (plating deposition amount of 90 g/m2 per side), in a
continuous hot-dip zinc plating production line, and the produced plated steel
sheet was
used as the original sheet for chemical treatment.
52
CA 3026697 2018-12-06
[0098] The surface of the original sheet for chemical treatment was degreased,
and dried.
Then, each of chemical treatment solutions Nos. 19 to 50 shown in Tables 2-1,
2-2, 3-1, 3-2,
4-1, and 4-2 was applied to the surface of the original sheet for chemical
treatment, and
immediately thereafter heated and dried at a low temperature (a temperature of
the steel
strip of 40 or 80 C) using an automatic discharge type electric hot air oven
to form a
chemical conversion film. Thus, chemically treated steel sheets Nos. 107 to
170 were
produced.
[0099] For a test specimen cut out from each chemically treated steel sheet,
the structure
of the chemical conversion film was identified; the percentage of pentavalent
vanadium
.. based on mixed-valent vanadium in the film was determined; the film
deposition amount
was measured; and the test specimen was subjected to corrosion resistance test
and
blackening resistance test. The chemical treatment solutions used, the ratio
of each
element in the chemical conversion film, the results of the corrosion
resistance test, and the
results of the blackening resistance test for each chemically treated steel
sheet are shown in
.. Tables 12-1, 12-2, 13-1, 13-2, 14-1, 14-2, 15-1, and 15-2. Note that the
ratio of each
element in the chemical conversion film is represented as parts by mass of
each element
based on 100 parts by mass of zirconium.
53
CA 3026697 2018-12-06
.
.
o
(..) o [0100]
1..)
01
01 Table 12-1
l0
....1
Ratio of Each Element
tv
in Chemically Treated Film
o Chemically Treated Chemical
Film Drying
1-,
(Parts by Mass)
co
I Category Steel Sheet Treatment Solution Deposition
Amount Temperature
1-,
iv No. No. (mg/m2)
( C)
I
Mo V P
0
01
Ex. 107 19 200 40
56.5 20.0 50.0
Ex. 108 20 500 40
1.9 2.0 50.0
Ex. 109 21 500 40
60.0 20.0 1.3
_
Ex. 110 22 100 40
480.0 160.0 5.0
Ex. 111 23 300 40
60.0 20.0 50_0
Ex. 112 24 1000 40
42.2 14.9 1.8
Ex. 113 25 500 40
39.6 6.0 5.0
Ex. 114 26 400 40
0.5 0.7 42.9
_
Ex. 115 27 250 40
60.0 20.0 50.0
Ex. 116 28 100 40 ,
94.2 11.1 1.9
Ex. 117 _ 29 150 40
2.0 2.2 1.1
Ex. 118 30 50 40
131.8 20.0 5.0
Ex. 119 31 100 40
46.7 26.7 6.7
Ex. 120 32 400 40
1.5 2.0 5.0
Ex. 121 33 250 40
3.5 1.3 1.3
Ex. 122 34 10000 40
0.2 0.3 1.3
54
*
C)
w
o Table 12-2
1..)
o,
in
to Chemically Treated Chemical
Evaluation Results
...1 Category Steel Sheet Treatment Solution V5+
Corrosion Resistance Blackening
Iv
0 No. No. Percentage
Flat Part Worked Part Resistance
1-.
0 Ex. 107 19 0.91
B B A
1
1-. Ex. 108 20 0.78
A A A
iv .
01
Ex. 109 21 0.87
B B A
cl,
Ex. 110 22 _ 0.82
B B A
Ex. 111 23 0.88
B B A
-
Ex. 112 24 0.77
B B A
Ex. 113 25 0.73
B B A
. -
Ex. 114 26 0.99
B B B
Ex. 115 27 0.73
B B A
.
.
Ex. 116 28 0.79
B B A
Ex. 117 29 0.89
B B A
Ex. 118 30 0.91
A B A
Ex. 119 31 0.87
B B A
Ex. 120 32 0.89
B B A
Ex. , 121 33 0.74
B B A
Ex. 122 34 0.86
B B B
=
C)
43 [0101]
0
IQ
Table 13-1
cil
to
--.1
Ratio of Each Element
NI
in Chemically Treated Film
o Chemically Treated
Drying
1-. Trted Chemical Fl
D Warts by Mass)
03 Category Steel Sheet Treatment Solution Deposition
Amount Temperature
1
1-. No. No. (mg/m2)
( C)
i.)
Mo V P
1
0
Ex. 123 35 1000 40
75.3 16.0 5.0
Ex. 124 36 300 40
71.6 23.9 1.5
_
Ex. 125 37 300 40
25.0 14.3 3.6
Ex. 126 38 150 40
0.2 0.3 1.5
_
Ex. 127 39 1000 40
7.8 0.8 50.0
_ _
'
Ex. 128 40 500 40
36.7 39.0 2.4
_ _
Ex. 129 41 100 40
60.0 20.0 50.0
_
Ex. 130 42 300 40
0.2 0.3 50.0
Ex. . 131 43 150 40
9.4 10.0 5.0
Ex. 132 44 50 40 ,
51.6 17.2 1.1
_ _ . Ex. 133 45 200 40
87.2 18.5 27.8
. _
Ex. 134 46 ' 300 40
480.0 160.0 5.0
. _
Ex. 135 47 50 40
0.2 0.3 50.0
.
_
Ex. 136 48 200 40
0.3 0.4 27.8
Ex. 137 49 250 40
1.5 2.0 5.0
. _
Ex. 138 50 50 40
188.3 40.0 80.0
56
= '
a
Table 13-2
w,
0
m Chemically Treated Chemical
Evaluation Results
o)
ch Category Steel Sheet Treatment Solution V5+
Corrosion Resistance Blackening
to
...1 No. No. Percentage _ Flat Part
, Worked Part Resistance
N A 0 Ex. 123 35 0.90 A B
, . _ _
1-. Ex. 124 36 0.82 B
B A
co .
I ¨
1-. Ex. 125 37 0.82 B
B A
_
N ¨
1 Ex. 126 38 0.87 A
A B .
0 .
(3) Ex. 127 39 0.90 B
B B
,
Ex. 128 40 0.77 B B
A
,
.
Ex. 129 .
41 0.77 A
A A
_
Ex. 130 42 0.77 B B
B
_ _
Ex. 131 43 0.85 B B
A
_ ,
Ex. 132 _ 44 0.80 B B
A
_
Ex. 133 45 0.77 A A
A
_
Ex. 134 46 0.79 B B
A
, Ex. 135 47 0.80 B B
B .
_
Ex. 136 48 0.74 B B
B
¨ _
Ex. 137 49 0.81 , B B
A
, _
¨ .
Ex. 138 50 0.93 A A
A
A
57
' =
C)
w
o [0102]
it)
0,
in Table 14-1
to
=-.1 Ratio of Each Element
it)
o in Chemically Treated Film
1-. Chemically Treated Chemical Film
Drying
(Parts by Mass)
co Category Steel Sheet Treatment Solution Deposition
Amount Temperature
,
1-.
KJ No. No. (mg/m2)
( C)
Mo V P
1
0
0,
'
Ex. 139 19 200
80 56.5 20.0 50.0
Ex. 140 20 500 .
80 1.9 2.0 50.0
Ex. 141 21 500
80 60.0 20.0 1.3
Ex. 142 22 100
80 480.0 160.0 5.0
Ex. 142 23 300
80 _ 60_0 20.0 50.0
Ex. 144 24 1000
80 , 42.2 14.9 1.8
Ex. 145 25 500
80 39.6 6.0 5.0
Ex. 146 26 400
80 0.5 , 0.7 42.9
-
Ex. 147 27 250
80 60.0 20.0 50.0
Ex_ , 148 28 100
80 94.2 11.1 1.9
.
.
Ex. 149 29 150
80 2.0 2.2 1.1
Ex. 150 30 50
80 131.8 20.0 5.0
.
_
Ex. 151 31 100
80 46.7 26.7 6.7
Ex. 152 32 400
80 1.5 2.0 5.0
Ex. 153 33 250
80 3.5 , 1.3 1.3
Ex. 154 34 10000
80 0.2 0.3 1.3
-
58
=
=
(-)
D., Table 14-2
w
cp Chemically Treated Chemical
Evaluation Results
m
0, Category Steel Sheet Treatment Solution V5+
Corrosion Resistance Blackening
0)
1
li) No. No. Percentage
Flat Part Worked Part Resistance
-.1
m Ex. 139 _ 19 0.73
B B A
cp
1-= Ex. 140 20 0.78
A A A
co
_
' Ex. 141 21 0.78
B B A
1--µ _
m
1 Ex. 142 22 0.78
B B A
.
o _ ¨
ch Ex. 143 23 0.86
B B A
. .
Ex. 144 24 0.74
B B A
r
_ Ex. 145 25 ,
0.90
B B A
. _
. Ex. 146 26 0.85
B B B
.
.
Ex. 147 . 27 0.87
B B A
Ex. 148 28 0.91
B B A
.
.
_ Ex. 149 29 0.95
B 13 A
Ex. 150 30 0.79
A B A
. _ -
Ex. 151 31 0.91
B B A
_
Ex. 152 32 0.78
B B A
Ex. 153 33 0.94
13 B A
Ex. 154 34 0.94
II B B
59
=
a
w [0103]
0
I)
01
01 Table 15-1
lO
..)
Ratio of Each Element
n)
in Chemically Treated Film
o Chemically Treated Chemical Film
Drying
I-.
CO
(Parts by Mass)
1 Category Steel Sheet Treatment Solution Deposition Amount
Temperature
1-,
n) No. No. (mg/m2)
( C)
I
Mo V P
0
01 . .
Ex. 155 35 1000 80
75.3 16.0 5.0
. _
Ex. 156 36 300 80
71.6 23.9 1.5
Ex. 157 _ 37 _
300
80 25.0 14.3 3.6
_ --
-
Ex. 158 38 150 80
0.2 0.3 1.5
_ _
Ex. 159 39 1000 80
7.8 0.8 _ 50.0
. _
Ex. 160 40 500 80
36.7 39.0 2.4
. .
Ex. 161 41 100 80
60.0 20.0 50.0
Ex. 162 . 42 300 80
0.2 0.3 50.0
_ _
Ex. 163 43 150 80
9.4 10.0 5.0
. _
Ex. 164 44 50 80
51.6 17.2 1.1
. _
Ex. 165 45 200 80
87.2 18.5 27.8
_
Ex. 166 46 300 80
480.0 160.0 5.0
_ _
Ex. 167 47 50 80
0.2 0.3 50.0
_
Ex. 168 48 _ 200 80
0.3 0.4 27.8
= Ex. 169 49
250 80 1.5 2.0 5.0
. _
Ex. 170 50 50 80
188.3 40.0 80.0
-
(-)
D.,
w
cp Table 15-2
m
0, Chemically Treated Chemical
Evaluation Results
0)
l0 Category Steel Sheet Treatment Solution V5+
Corrosion Resistance Blackening
-.1
No. No. Percentage _.
Flat Part Worked Part Resistance
r.) .
cp
1_µ Ex. 155 35 0.91
A B A
co _ _
1 Ex. 156 36 0.82
B B A
1-, , .
r.) Ex. 157 37 0.82
B B A
1
.
cp Ex. 158 38 0.86 _
0,
Ex. -
A A B
159 39 0.84 _
B
B B
Ex. 160 40 _ 0.87 _
B
B A
Ex. 161 41 0.78
A A A
Ex. 162 42 0.84
B _
B
B
Ex. 163 43 0.96
B B A
Ex. 164 44 0.82 _
B
B A
_
Ex. 165 45 0.82 _
A
A A
.
Ex. 166 46 0.74
B B A
Ex. 167 47 0.68
B B B
_
Ex. 168 48 0.83
B B B
_
Ex. 169 49 0.87
B B A
Ex. 170 50 0.78 _
A
A A
61
[0104] As is obvious from Tables 12-1, 12-2, 13-1, 13-2, 14-1, 14-2, 15-1, and
15-2, it
can be found that all chemically treated steel sheets each having a chemical
conversion
film in which the percentage of pentavalent vanadium based on mixed-valent
vanadium in
the chemical conversion film is 0.7 or more, and which includes a first
chemical
conversion layer containing vanadium, molybdenum and phosphorus, and a second
chemical conversion layer disposed on the first chemical conversion layer and
containing a
group 4A metal oxoate, the chemical conversion film being disposed on the
surface of a
zinc-based plated steel sheet having a zinc-based plating layer containing 0.1
to 22.0
mass % of aluminum have favorable corrosion resistance and blackening
resistance. The
chemical conversion film is obtained by applying a chemical treatment solution
which
contains a water-soluble molybdate, a vanadium salt, an amine, a group 4A
metal oxoate,
and a phosphate, in which the molar ratio of molybdenum to vanadium is 0.4 to
5.5, and
the molar ratio of an amine to vanadium is 0.3 or more to the zinc-based
plated steel sheet,
followed by drying. The favorable corrosion resistance and blackening
resistance of the
chemically treated steel sheets are obtained in a wide range of the deposition
amount of the
chemical conversion film, even when the chemical treatment solution is dried
at a
relatively low drying temperature.
[0105] It can be found, from the above-mentioned results, that the chemically
treated
steel sheet of the present invention is excellent in worked part corrosion
resistance and
blackening resistance even when the chemical treatment solution is dried at a
low
temperature and for a short period of time.
[0106] [Example 4]
[Preparation of Chemical Treatment Solution No. 51]
Ammonium molybdate, vanadium pentoxide, ethanolamine, ammonium
zirconium carbonate (AZC), diammonium hydrogen phosphate, which are shown in
Table
1, and water were mixed such that the concentrations are as shown in Tables 16-
1 and 16-2
62
CA 3026697 2018-12-06
to obtain chemical treatment solution No. 51. The composition and color of
each
chemical treatment solution are shown in Tables 16-1 and 16-2. In Table 16-2,
"MoN"
indicates the molar ratio of a molybdenum element to a vanadium element, and
"amine/V"
indicates the molar ratio of an amine to a vanadium element.
[0107] [Preparation of Chemical Treatment Solutions Nos. 52 to 57]
Chemical treatment solutions Nos. 52 to 57 were each obtained in the same
manner as chemical treatment solution No. 51 except that molybdenum
concentration, the
type of the vanadium salt and vanadium concentration, the type and
concentration of the
amine, zirconium concentration, and the type of the phosphate and phosphate
concentration
were changed as shown in Tables 16-1 and 16-2.
63
CA 3026697 2018-12-06
-
=
C) [0108]
ao
LO
0 Table 16-1
m
0) M1 Vanadium Salt
Amine
0, Chemical
ko --.3 Treatment Solution Mo V
Conc. Category
tv Conc. Compound Conc.
Compound
0 No.
(g/L)
F. (g/L) (WO
co
i 51 0.075 VI 0.10 _
EA 0.036
F. _
tv 52 0.075 V2 0.10
NH 0.021
1
0
0, 53 24.0 V2 8.00
EA 15.3
54 1.98 V3 0.30
EA 1.15 Ex.
55 3.11 V3 0.30
IPA 1.06
56 24.0 V2 . 8.00
NH 8.79
_
57 14.1 V2 0.30
EN 5.75
Table 16-2
AZC Phosphate
Chemical
Color of
Zr P Mo/V
Amine/V
Treatment Solution
Treatment Category
Conc. Compound Conc.
(Molar Ratio) (Molar Ratio)
No
Solution
(g/L) , , WO -
51 5.0 P1 0.25 0.40
0.30 Yellow
.1
52 5.0 P5 0.05 0.40
0.30 Yellow
53 40.0 P4 2.00 1.59
_ 1.60 Yellow
54 5.0 P3 0.25 , 3.50
3.20 Yellow Ex.
55 40.0 P4 20.0 _ 5.50
2.40 Yellow
_
56 _ 46.5 P2 0.50 1.59
1.60 Yellow
, _
57 7.5 P4 6.00 2.50
1.60 Yellow
64
[0109] [Preparation of Chemical Treatment Solutions Nos. 58 to 641
Chemical treatment solutions Nos. 58 to 64 were each obtained in the same
manner as chemical treatment solutions Nos. 1 to 57 except that an organic
resin as a
hydrophilic resin is further mixed such that the organic resin has a
concentration as shown
in Tables 17-1 and 17-2. In Table 17-2, "AR" indicates denotes an acrylic
resin, "PO"
denotes a polyolefin, "ER" denotes an epoxy resin, and "PU" denotes
polyurethane. In
addition, the amount of an organic resin in Table 17-2 is the amount (mass %)
of an organic
resin based on the total amount of vanadium and molybdenum in the chemical
treatment
solution.
[0110] It is noted that VoncoatTM 40-418EF" manufactured by DIC Corporation
(the
VoncoatTM" is a registered trademark of this company) was used as "acrylic
resin";
"Zaikthenem" A type-AC manufactured by Sumitomo Seika Chemicals Co., Ltd.
("Zaikthenem" is a registered trademark of this company) was used as
"polyolefin";
"Adeka Resin1m EM-0434AN" manufactured by Adeka Corporation ("Adeka Resin'TM"
is a
registered trademark of this company) was used as "epoxy resin"; and "Adeka
BontighterIm HUX-232" manufactured by Adeka Corporation ("Adeka Bontighter'TM"
is a
registered trademark of this company) was used as ``polyurethane."
[0111] [Preparation of Chemical Treatment Solutions Nos. 65 and 661
Chemical treatment solutions Nos. 65 and 66 were each obtained in the same
manner as chemical treatment solution No. 51 except that molybdenum
concentration, the
type of the vanadium salt and vanadium concentration, the type and
concentration of the
amine, zirconium concentration, the type of the phosphate and phosphate
concentration,
and the type and concentration of the organic resin were changed as shown in
Tables 17-1
and 17-2.
Date Recue/Date Received 2020-11-03
'
C)
w
o [0112]
F'.)
01
01 Table 17-1
(0
,.., M1 Vanadium Salt
Amine AZC
A) Chemical
o Mo
V Zr
1-, Treatment Solution
Conc. Category
co Conc. Compound Conc. Compound
Conc.
1 No.
(g/L)
1- (g/L) (g/14)
(g/L)
m
' 58 0.075 V1 0.10 EA
0.036 5.0 Comp. Ex.
o
01 59 0.075 V2 0.10 NH
0.021 5.0 Comp. Ex.
60 24.0 V2 8.00 EA
15.3 40.0 Ex.
61 _ 1.98 V3 0.30 EA
1.15 5.0 Comp. Ex.
62 3.11 V3 0.30 IPA
1.06 40.0 Ex.
63 24.0 V2 _ 8.00 _ NH
8.79 46.5 Ex.
64 14.1 V2 0.30 EN
5.75 7.5 Comp. Ex.
65 1.00 _ V1 0.30
IPA 2.00 1.0 Comp. Ex.
66 1.00 V1 0.30 IPA
2.00 1.0 Comp. Ex.
Table 17-2
Phosphate Organic Resin
Chemical
Color of
P Mo/V Amine/V
Treatment Solution Conc. Amount
Treatment Category
Compound Conc. Compound (Molar Ratio) (Molar Ratio)
No. (a) (mass %) Solution
(g11.)
58 P1 0.25 AR 50.0 28500
0.40 0.30 Yellow Comp. Ex.
59 P5 0.05 PO 80.0 45600 _
0.40 0.30 Yellow Comp. Ex.
60 P4 2.00 ER 20.0 63.0
1.59 1.60 Yellow Ex.
61 P3 0.25 AR 5.00 220
3.50 3.20 Yellow Comp. Ex.
62 P4 20.0 PO , 0.50 15.0
5.50 2.40 Yellow Ex.
63 P2 0.50 ER 20.0 63.0
1.59 1.60 Yellow Ex. _
64 P4 6.00 PU 200 1170
2.50 1.60 Yellow Comp. Ex. _
65 - PU 200 13300
0.53 2.72 Yellow Comp. Ex.
66 P1 1.00 PU 200 13300
0.53 2.72 Yellow Comp. Ex.
66
[0113] [Preparation of Chemical Treatment Solutions Nos. 67 to 73]
Chemical treatment solutions Nos. 67 to 73 were each obtained in the same
manner as chemical treatment solutions Nos. 51 to 57 except that a fluorine
compound that
produces a fluorine ion or a fluorometal ion in water is further mixed such
that the fluorine
compound has a concentration as shown in Tables 18-1 and 18-2. The amount of a
fluorine compound in Table 18-2 is the amount (mass %) of a fluorine element
based on the
total amount of vanadium and molybdenum in the chemical treatment solution.
The
fluorine element is derived from a fluorine ion or a fluorometal ion in the
chemical
treatment solution.
67
CA 3026697 2018-12-06
'
'
C)
w [0114]
o
F-.)
01
01 Table 18-1
(0
,.., M1 Vanadium Salt
Amine AZC
A) Chemical
Mo V Zr
o
1-, T
(g/L) Na Treatment Solution Conc. Category
co Conc. Compound Conc.
Compound Conc.
1
(g/L) , (g/L) (g/L)
m
1 67 0.075 V1 0.10 s EA
0.036 5.0 Comp. Ex.
0
01 68 0.075 V2 0.10 NH
0.021 5.0 Comp. Ex.
69 24.0 V2 8.00 EA
15.3 40.0 Ex,
70 1.98 V3 0.30 EA
1.15 5.0 Ex.
71 , 3.11 V3 0.30 IPA
1.06 40.0 Comp. Ex.
72 24.0 V2 8.00 NH
8.79 46.5 Comp. Ex.
73 14.1 V2 0.30 EN
5.75 7.5 Comp. Ex.
-
Table 18-2
Phosphate Fluorine
Compound
Chemical
Color of
P MoN AmineN
Treatment Solution Conc. Amount
Treatment Category
No. Compound Conc. Compound
(g/L) (mass %)
Solution
Ratio)
(Molar Ratio) Solution
(g/L)
.
-
67 P1 0.25 Fl 2.00 373
0.40 0.30 Yellow Comp. Ex.
68 P5 0.05 F2 1.00 570
0.40 0.30 Yellow Comp. Ex.
69 P4 2.00 F3 0.50 2.00
1.59 1.60 Yellow Ex.
70 P3 0.25 Fl 0.50 22.0
3.50 3.20 Yellow Ex.
71 P4 20.0 F2 10.0 293
5.50 2.40 Yellow Comp. Ex.
_
_
72 P2 0.50 F3 50.0 156
1.59 . 1.60 Yellow Comp. Ex.
73 P4 6.00 Fl 20.0 117
2.50 1.60 Yellow Comp. Ex.
68
[0115] [Preparation of Chemical Treatment Solutions Nos. 74 to 80]
Chemical treatment solutions Nos. 74 to 80 were each obtained in the same
manner as chemical treatment solutions Nos. 51 to 57 except that a silicon
compound that
produces a silanol group in water is further mixed such that the silicon
compound has a
concentration as shown in Tables 19-1 and 19-2. The amount of a silicon
compound in
Table 19-2 is the amount (mass %) of a silicon element based on the total
amount of
vanadium and molybdenum in the chemical treatment solution. The silicon
element is
derived from a silanol group in the chemical treatment solution.
69
CA 3026697 2018-12-06
=
C)
[0116]
w
0
IQ Table 19-1
0,
0,
k0 M1 Vanadium Salt
Amine AZC
--) Chemical
Mo V
Zr
n) Treatment Solution
Conc. Category
o Conc. Compound
Conc. Compound Conc.
1-, No.
(g/L)
co , (g/L) (g/L) _
(g/L)
.
I
_
1-,
_
n) 74 0.075 V1 0.10 EA
0.036 5.00 Comp. Ex.
. _
I
-
0 75 0.075 V2 0.10 NH
0.021 5.00 Comp. Ex.
_
0, 76 24.0 - V2 8.00 EA
15.327 40.0 Ex.
_
-
77 1.98 V3 0.30 EA
1.150 5.00 Comp. Ex.
-
78 3.11 V3 0.30 IPA
1.060 , 40.0 Comp. Ex.
79 24.0 V2 8.00 NH
8.794 46.5 Ex.
-
80 14.1 V2 0.30 , EN
, 5.748 7.50 Comp. Ex.
_
_ Table 19-2
Phosphate Silicon Compound
Chemical
Color of
P
Mo/V Amine/V
Treatment Solution Conc. Amount
Treatment Category
No. Compound Conc. Compound (a) (mass A) (Molar
Ratio) (Molar Ratio)
Solution
-
, (g/L) . -
,
74 P1 0.25 Si2.00 179
0.40 0.30 Yellow Comp. Ex.
. _ _ .
75 P5 0.05 S2 5.00 2850
0.40 0.30 Yellow Comp. Ex.
_.
76 P4 2.00 S3 0.20 1.00
1.59 1_60 Yellow Ex.
,
77 P3 _ 0.25 _ Si 5.00 220
3.50 3.20 Yellow Comp. Ex.
_
_
78 P4 20.0 S2 8.00 235
5.50 2.40 _ Yellow Comp. Ex.
79 P2 , 0.50 S3 _ 10.0 31.0 _
1.59 1.60 Yellow Ex.
80 P4 , 6.00 Si , 20.0 117
2.50 1.60 Yellow Comp. Ex.
[0117] Note that, in order to prevent vanadium from being reduced in the
preparation of
the chemical treatment solution, a vanadium salt was added to and dissolved in
an aqueous
solution having a liquid temperature of 40 C or lower containing an amine. It
is
considered that, since the color of each chemical treatment solution is
yellow, the valence
of vanadium contained in each chemical treatment solution is pentavalent
(V5+).
[0118] [Production of Chemically Treated Steel Sheets Nos. 171 to 200]
The surface of the original sheet for chemical treatment was degreased, and
dried.
Then, chemical treatment solution No. 51 shown in Tables 16-1 and 16-2 was
applied to
the surface of the original sheet for chemical treatment in the amount of the
deposition
amount of chemical conversion film shown in Table 20-1, and immediately
thereafter
heated and dried at a drying temperature of (a temperature of the steel strip
of) 40 C for 2
seconds using an automatic discharge type electric hot air oven to form a
chemical
conversion film. Thus, chemically treated steel sheet No. 171 was produced.
[0119] Further, chemical treatment solutions Nos. 52 to 80 were used in place
of
.. chemical treatment solution No. 51 to respectively produce chemically
treated steel sheets
Nos. 172 to 200 in the same manner as chemically treated steel sheets No. 51,
except that
the chemical treatment solutions were applied to the original sheet for
chemical treatment
in the deposition amounts shown in Table 20-1 or 21-1, and heated and dried at
a drying
temperature shown in Table 20-1 or 21-1. Note that the drying time is 6
seconds when the
.. drying temperature is 80 C.
101201 [Measurement and Evaluation of Chemically Treated Steel Sheets]
For a test specimen cut out from each chemically treated steel sheet, the
structure
of the chemical conversion film was identified, and the test specimen was
subjected to
corrosion resistance test and blackening resistance test in the same manner as
Example 1.
[0121] As a result, it was confirmed, in chemically treated steel sheets
categorized in
Examples, that the two-layer structure (i.e., first and second chemical
conversion layers)
71
CA 3026697 2018-12-06
similar to chemically treated steel sheet No. 17, for example, contains
vanadium,
molybdenum and phosphorus in the first chemical conversion layer and a group
4A metal
=
oxoate in the second chemical conversion layer. However, the two-layer
structure in the
chemical conversion film was not confirmed in chemically treated steel sheets
categorized
in Comparative Examples.
[0122] The type of chemical treatment solutions, deposition amount, drying
temperature,
the content of molybdenum, vanadium and phosphorus in the chemical conversion
film, the
percentage of pentavalent vanadium, and various evaluation results are each
shown in
Tables 20-1, 20-2, 21-1, and 21-2. Note that each content ratio of molybdenum,
vanadium and phosphorus indicates parts by mass of each element based on 100
parts by
mass of a zirconium element.
72
CA 3026697 2018-12-06
0
L)
0 [0123]
ll)
01
01
Table 20-1
=-JI
Ratio of Each Element
n) Chemical Chemical Drying
o in Chemically Treated Film
I.,
co Treatment Solution Treatment Solution Temperature
Category
Deposition Amount
1
No. No. (Parts by
Mass)
(mg/m2) ( C)
1-,
r,) Mo V P
,
I .
o 171 51 200
40 1.5 2.0 5.0 Ex.
0, -
_
172 - 52 200 80 1.5 2.0
1.0 Ex.
.
_
173 53 200 40 60.0 20.0
5.0 Ex.
,
174 54 500 40 , 39.6 6.0
5.0 Ex.
175 55 1000 40 7.8 0.8
50.0 Ex.
176 56 50 40 51.6 17.2
1.1 Ex.
177 ,_ 57 50 80 188.3 40.0
80.0 Ex.
, 178 . 58 200 40 1.5 2.0
5.0 Comp. Ex.
179 59 200 80 1.5 2.0
1.0 Comp. Ex.
180 60 200 40 60.0
, 20.0 5.0 Ex.
181 61 500 40 39.6 6.0
5.0 Comp. Ex.
_ _
.
182 62 1000 40 7.8 0.8
50.0 Ex.
-
183 63 300 40 480.0
160.0 5.0 Ex.
184 64 50 80 188.3
. 40.0 80.0 Comp. Ex.
185 65 200 80 100.0 50.0
. 0.0 Comp. Ex.
186 66 200 80 100.0 50.0
100.0 Comp. Ex.
73
-
o
w
c, Table 20-2
ll)
01
01
to Chemical Chemical Evaluation
Results
=-11
Treatment Solution Treatment Solution Flat Part
Worked Part Blackening Category
ni V5+N
o No. No.
Corrosion Resistance Corrosion Resistance Resistance
1.,
c 171 51 0.92 A
A A Ex.
1
1-,
ni 172 52 0.81 B
B A Ex.
o1 _
173 53 0.92 B B
A Ex.
174 54 0.85 A A
A Ex.
175 55 0.71 A A
A , Ex.
_
176 56 0.79 A A
A Ex.
177 57 ¨ 0.79 B B
A Ex.
.
178 58 0.85 D D
C Comp. Ex.
_
179 59 0.71 D D
D . Comp. Ex.
_
180 _ 60 0.93 B B
A Ex.
- 181 61 0.63 D D
C Comp. Ex.
_
182 62 0.82 A A
A , Ex.
183 63 0.95 A A
A Ex.
184 _ 64 0.75 D D
D , Comp. Ex.
185 65 0.72 D D
D Comp. Ex.
_ _
186 66 0.78 C D
D Comp. Ex.
74
' =
C)
w
o [0124]
m
01
01 Table 21-1
(0
-1
Ratio of Each Element
n) Chemically Treated Chemical Steel Sheet Treatment
Solution Drying
0 Deposition Amount
in Chemically Treated Film
1-,
Category
co (mg/m2) Temperature
(Parts by Mass)
1 No. No. ( C)
1-
Mo V P
iv
I 187 67 200 40
1.5 2.0 5.0 Comp. Ex.
0 ,
01 188 68 200 80
_
1.5 2.0 1.0 Comp. Ex.
. .
189 69 200 40
60.0 20.0 5.0 Ex.
190 70 500 40
39.6 6.0 5.0 Ex.
. .
191 71 1000 40
7.8 0.8 50.0 Comp. Ex.
_
192 72 300 40
480.0 , 160.0 5.0 Comp. Ex.
193 73 50 80
188.3 40.0 80.0 Comp. Ex.
. .
194 74 200 40
1.5 2.0 5.0 Camp. Ex.
. .
195 75 . 200 80
1.5 2.0 1.0 Comp. Ex.
196 76 200 40
60.0 20.0 5.0 Ex.
197 77 500 40
39.6 6.0 5.0 Comp. Ex.
_
198 78 1000 40
7.8 0.8 50.0 Comp. Ex.
_ .
199 79 300 40
480.0 160.0 5.0 Ex.
_
200 80 50 80
188.3 40.0 80.0 Comp, Ex.
.
,
C)
co
0 Table 21-2
r..)
0, Chemically Treated Chemical
Evaluation Results
01
to Steel Sheet Treatment Solution V5+AT Flat Part
Worked Part Blackening Category
--.1
No. No. Corrosion Resistance
Corrosion Resistance Resistance
n.)
0
1-. 187 67 0.85 D
D D Comp. Ex.
co
1 188 68 0.81 D
D D Comp. Ex.
1-.
" 189 69 0.92 B
B A Ex.
1
0 190 70 0.90 A
A A Ex.
0,
191 71 0.68 D
D D Comp. Ex.
192 72 , 0.75 D
D D Comp. Ex.
193 73 , 0.74 D
D D Comp. Ex.
194 74 0.81 C
D D Comp. Ex.
195 75 _ 0.79 D
D D Comp. Ex.
196 76 0.95 B
B A Ex.
197 77 0.84 C
D D Comp. Ex.
198 78 0.76 . C
D D Comp. Ex.
199 79 0.93 A
A A Ex.
200 80 0.78 C
D D Comp. Ex.
76
[0125] As is obvious from Tables 16-1, 16-2 and 20-1, 20-2, in chemically
treated steel
sheets Nos. 171 to 177 obtained using, respectively, chemical treatment
solutions Nos. 51
to 57, all of flat part corrosion resistance, worked part corrosion resistance
and blackening
resistance were sufficiently favorable.
[0126] However, as is obvious from Tables 17-1, 17-2 and 20-1, 20-2, in
chemically
treated steel sheets Nos. 178 to 184 obtained using, respectively, chemical
treatment
solutions Nos. 58 to 64 having the same compositions as those of chemical
treatment
solutions Nos. 51 to 57 except containing a hydrophilic resin, at least one of
flat part
corrosion resistance, worked part corrosion resistance and blackening
resistance were
insufficient at times. Specifically, in chemically treated steel sheets Nos.
180, 182 and
183 using, respectively, chemical treatment solutions Nos. 60, 62 and 63
having a relatively
low concentration of a hydrophilic resin, all of flat part corrosion
resistance, worked part
corrosion resistance and blackening resistance were sufficiently favorable. In
contrast, in
chemically treated steel sheets Nos. 178, 179, 181 and 184 obtained using,
respectively,
.. chemical treatment solutions Nos. 58, 59, 61 and 64 having a relatively
high concentration
of a hydrophilic resin, all of flat part corrosion resistance, worked part
corrosion resistance
and blackening resistance were insufficient. This is considered to be because
the content
of a hydrophilic resin at a relatively high concentration in a chemical
treatment solution
inhibits the formation of the two-layer structure in the chemical conversion
film.
[0127] Also in chemically treated steel sheets Nos. 185 and 186, all of flat
part corrosion
resistance, worked part corrosion resistance and blackening resistance were
insufficient.
This is considered as follows: chemical treatment solutions Nos. 65 and 66
contain a
hydrophilic resin at a high concentration regardless of the presence/absence
of phosphorus
even though "MoN" and "amine/V" in chemical treatment solutions Nos. 65 and 66
are
the same, and thus the formation of the two-layer structure in the chemical
conversion film
is inhibited for the same reason as described above.
77
CA 3026697 2018-12-06
[0128] Further, as is obvious from Tables 18-1, 18-2 and 21-1, 21-2, in
chemically treated
steel sheets Nos. 187 to 193 obtained using, respectively, chemical treatment
solutions Nos.
67 to 73 having the same compositions as those of chemical treatment solutions
Nos. 51 to
57 except containing fluorine as a fluorine ion or a fluorometal ion, at least
one of flat part
corrosion resistance, worked part corrosion resistance and blackening
resistance were
insufficient at times. Specifically, in chemically treated steel sheets Nos.
189 and 190
using, respectively, chemical treatment solutions Nos. 69 and 70 having a
relatively low
concentration of fluorine, all of flat part corrosion resistance, worked part
corrosion
resistance and blackening resistance were sufficiently favorable. In
contrast, in
chemically treated steel sheets Nos. 187, 188, and 191 to 193 obtained using,
respectively,
chemical treatment solutions Nos. 67, 68, and 71 to 73 having a relatively
high
concentration of fluorine, all of flat part corrosion resistance, worked part
corrosion
resistance and blackening resistance were insufficient. This is considered to
be because
the content of the fluorine at a relatively high concentration in a chemical
treatment
solution inhibits the formation of the two-layer structure in the chemical
conversion film.
[0129] Further, as is obvious from Tables 19-1, 19-2 and 21-1, 21-2, in
chemically treated
steel sheets Nos. 194 to 200 obtained using, respectively, chemical treatment
solutions Nos.
74 to 80 having the same compositions as those of chemical treatment solutions
Nos. 51 to
57 except containing silicon derived from a silanol group, at least one of
flat part corrosion
resistance, worked part corrosion resistance and blackening resistance were
insufficient at
times.
Specifically, in chemically treated steel sheets Nos. 196 and 199 using,
respectively, chemical treatment solutions Nos. 76 and 79 having a relatively
low
concentration of silicon, all of flat part corrosion resistance, worked part
corrosion
resistance and blackening resistance were sufficiently favorable. In
contrast, in
chemically treated steel sheets Nos. 194, 195, 197, 198, and 200 obtained
using,
respectively, chemical treatment solutions Nos. 74, 75, 77, 78, and 80 having
a relatively
78
CA 3026697 2018-12-06
high concentration of silicon, all of flat part corrosion resistance, worked
part corrosion
resistance and blackening resistance were insufficient. This is considered to
be because
the content of the silicon at a relatively high concentration in a chemical
treatment solution
inhibits the formation of the two-layer structure in the chemical conversion
film.
.. [0130] As described above, it can be found that a chemically treated steel
sheet excellent
in worked part corrosion resistance and blackening resistance can be obtained
by applying,
to a zinc-based plated steel sheet having a zinc-based plating layer
containing 0.1 to 22.0
mass % of aluminum, a chemical treatment solution containing a water-soluble
molybdate,
a vanadium salt, an amine, a group 4A metal oxoate and a phosphate compound,
in which a
.. molar ratio of molybdenum to vanadium is 0.4 to 5.5, and a molar ratio of
the amine to the
vanadium is 0.3 or more; and the content of the hydrophilic resin is at most
100 mass %,
the fluorine concentration is at most 30 mass %, or the silicon concentration
is at most 50
mass %, based on the total amount of the vanadium and the molybdenum, even
when the
chemical treatment solution is dried at a low temperature and for a short
period of time.
[0131] This application claims the priority of Japanese Patent Applications
No.
2013-235543 filed on November 14, 2013, and Japanese Patent Applications No.
2014-231275 filed on November 14,2014.
Industrial Applicability
[0132] The chemically treated steel sheet of the present invention is
excellent in
corrosion resistance and blackening resistance, and is therefore useful for
wide applications
such as automobiles, building materials, and home electric appliances, for
example.
79
CA 3026697 2018-12-06
