U.S. patent application number 16/629484 was filed with the patent office on 2020-05-28 for chemical conversion treatment agent, coating pre-treatment method, and metal member.
The applicant listed for this patent is NIPPON PAINT SURF CHEMICALS CO., LTD.. Invention is credited to Masato KISHI, Takayuki UENO.
Application Number | 20200165741 16/629484 |
Document ID | / |
Family ID | 65002567 |
Filed Date | 2020-05-28 |
United States Patent
Application |
20200165741 |
Kind Code |
A1 |
KISHI; Masato ; et
al. |
May 28, 2020 |
CHEMICAL CONVERSION TREATMENT AGENT, COATING PRE-TREATMENT METHOD,
AND METAL MEMBER
Abstract
Provided is a chemical conversion treatment agent that has a
small impact on the environment and can ensure good post-coating
corrosion resistance regardless of the target of treatment. A
chemical conversion treatment agent including: at least one type
(A) of element selected from the group consisting of zirconium,
titanium, and hafnium; at least one type (B) of substance selected
from the group consisting of amino group-including silane coupling
agents, hydrolysates thereof, and polymers thereof; fluorine (C);
and a cationic urethane resin (D). Preferably, the content of (A)
is 20-10000 mass ppm in total in terms of metals, and the pH is
1.5-6.5.
Inventors: |
KISHI; Masato; (Tokyo,
JP) ; UENO; Takayuki; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NIPPON PAINT SURF CHEMICALS CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
65002567 |
Appl. No.: |
16/629484 |
Filed: |
July 12, 2018 |
PCT Filed: |
July 12, 2018 |
PCT NO: |
PCT/JP2018/026328 |
371 Date: |
January 8, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 22/34 20130101;
C25D 11/16 20130101; C25D 13/20 20130101 |
International
Class: |
C25D 11/16 20060101
C25D011/16 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 13, 2017 |
JP |
2017-137368 |
Claims
1. A chemical conversion treatment agent, comprising: at least one
(A) selected from the group consisting of zirconium, titanium, and
hafnium; at least one (B) selected from the group consisting of an
amino group-containing silane coupling agent, hydrolysates thereof,
and polymers thereof; fluorine (C); and a cationic urethane resin
(D).
2. The chemical conversion treatment agent according to claim 1,
wherein the total content of (A) is 20 to 10000 ppm by mass in
terms of metal, and pH is 1.5 to 6.5.
3. The chemical conversion treatment agent according to claim 1,
wherein the total content of (B) is 5 to 5000 ppm by mass in terms
of a solid content concentration, and the content of (D) is 5 to
5000 ppm by mass in terms of a solid content concentration, and the
solid content mass ratio ((B)/(D)) of (B) to (D) is 0.0002 to
5000.
4. The chemical conversion treatment agent according to claim 1,
further comprising at least one adhesiveness and corrosion
resistance-conferring agent selected from the group consisting of
magnesium ions, zinc ions, calcium ions, aluminum ions, gallium
ions, indium ions, and copper ions.
5. A pre-coating treatment method, comprising: treating a target
workpiece with the chemical conversion treatment agent according to
claim 1.
6. A metal member treated by the pre-coating treatment method
according to claim 5.
Description
TECHNICAL FIELD
[0001] The present invention relates to a chemical conversion
treatment agent, a pre-coating treatment method, and a metal
member.
BACKGROUND ART
[0002] Chemical conversion treatment is usually performed for the
purpose of improving properties such as corrosion resistance and
coating adhesiveness when a surface of a metal material is
subjected to cation electrodeposition coating, powder coating, or
the like. Chromate treatment is commonly used for chemical
conversion in view of its capability of further improving adhesion
and corrosion resistance of a coated film. In recent years, the
hazardous properties of chromium, however, have been noted, and
thus there have been demands for developing a chemical conversion
treatment agent which does not contain chromium. As such chemical
conversion, widely performed is zinc phosphate treatment.
[0003] However, zinc phosphate-based treatment agents contain high
concentrations of metal ions and acids, and are highly reactive.
This may result in poor waste-treatment economy and poor
workability. Further, when a metal surface is treated with a zinc
phosphate-based treatment agent, water-insoluble salts may be
generated and deposited as precipitates. These precipitates are
generally referred to sludge. The removal and disposal of such
sludge may add undesirable costs and other problems. Further,
phosphate ions may be responsible for increased environmental
burden due to eutrophication, and may require additional efforts
for waste treatment. Therefore, use of phosphate ions is preferably
avoided. Moreover, the treatment of a metal surface with a zinc
phosphate-based treatment agent requires surface conditioning.
This, disadvantageously, may result in a prolonged process.
[0004] As metal-surface treatment agent other than such a zinc
phosphate-based treatment agent or a chromate chemical conversion
treatment agent, known is a metal-surface treatment agent including
a zirconium compound. Such a metal-surface treatment agent
including a zirconium compound has a superior property as compared
with a zinc phosphate-based chemical conversion treatment agent as
described above in that the generation of sludge can be
prevented.
[0005] Unfortunately, a chemical conversion film obtained by a
metal-surface treatment agent including a zirconium compound shows
poor adhesiveness, in particular with a coated film obtained by
cation electrodeposition coating, and is less often used as a
pre-treatment step of cation electrodeposition coating. In such a
metal-surface treatment agent including a zirconium compound, a
component such as phosphate ions may be used in combination for
improving adhesiveness and corrosion resistance. However, when
phosphate ions are used in combination, the aforementioned problems
such as eutrophication may occur. Moreover, an iron-based base
material treated with such a metal-surface treatment agent may have
a problem in that neither sufficient coating adhesiveness nor
post-coating corrosion resistance can be obtained.
[0006] A non-chromate metal-surface treatment agent is also known
which includes a zirconium compound and an amino group-containing
silane coupling agent. However, surface treatment with such a
non-chromate metal-surface treatment agent as an application-type
treatment agent used in the field of so-called coil coating is not
comparable with post-treatment water-washing. Further, such a
non-chromate metal-surface treatment agent is not intended for a
target workpiece having a complicated shape.
[0007] Furthermore, for an article, such as an automobile body and
parts, composed of a metal material such as iron, zinc, and
aluminum, the entire metal surface may need to be treated in a
single treatment. Accordingly, a pre-coating treatment method is
desired to be developed, by which chemical conversion can be
performed without causing any problem even in such a case.
Meanwhile, a pre-coating treatment method is also desired to be
developed, by which chemical conversion can be performed without
causing the aforementioned problems even in coating other than
cation electrodeposition coating using a powder coating material, a
solvent coating material, a water-based paint, and the like.
[0008] In an attempt to solve the above problems, a pre-coating
treatment method is known, the method involving treating a target
workpiece with a chemical conversion treatment agent including at
least one selected from the group consisting of zirconium,
titanium, and hafnium; fluorine; and at least one selected from the
group consisting of an amino group-containing silane coupling
agent, hydrolysates thereof, polymers thereof to form a chemical
conversion film (for example, see Patent Document 1 below).
[0009] The above pre-coating treatment method is compatible with
any common coating methods, and can provide similar adhesiveness
and post-coating corrosion resistance as a case where a zinc
phosphate-based chemical conversion treatment agent is used.
However, post-coating corrosion resistance obtained was less than
satisfactory, depending on a treatment target and applications
thereof.
[0010] Patent Document 1: Japanese Unexamined Patent Application,
Publication No. 2004-218070
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0011] The present invention is made in view of the above
circumstances. An object of the present invention is to provide a
chemical conversion treatment agent which may cause less
environmental burden, and can ensure good post-coating corrosion
resistance regardless of treatment targets.
Means for Solving the Problems
[0012] The present invention relates to a chemical conversion
treatment agent including at least one (A) selected from the group
consisting of zirconium, titanium, and hafnium; at least one (B)
selected from the group consisting of an amino group-containing
silane coupling agent, hydrolysates thereof, and polymers thereof;
fluorine (C); and a cationic urethane resin (D).
[0013] Further, it is preferred that the total content of (A) is 20
to 10000 ppm by mass in terms of metal, and pH is 1.5 to 6.5.
[0014] Moreover, it is preferred that the total content of (B) is 5
to 5000 ppm by mass in the solid content concentration, and the
content of (D) is 5 to 5000 ppm by mass in the solid content
concentration, and, the solid content mass ratio ((B)/(D)) of (B)
to (D) is 0.0002 to 5000.
[0015] Moreover, it is preferred to further contain at least one
adhesiveness and corrosion resistance-conferring agent selected
from the group consisting of magnesium ions, zinc ions, calcium
ions, aluminum ions, gallium ions, indium ions, and copper
ions.
[0016] The present invention also relates to a pre-coating
treatment method including treating a target workpiece with the
above chemical conversion treatment agent.
[0017] Further, the present invention relates to a metal member
treated by the above pre-coating treatment method.
Effects of the Invention
[0018] The present invention can provide a chemical conversion
treatment agent which may cause less environmental burden, and can
ensure good post-coating corrosion resistance regardless of
treatment targets.
PREFERRED MODE FOR CARRYING OUT THE INVENTION
[0019] Below, the embodiments of the present invention will be
described. It is noted that the present invention shall not be
limited to the following embodiments.
[0020] <Chemical Conversion Treatment Agent>
A chemical conversion treatment agent according to the present
embodiment can form a chemical conversion film on a metal surface
as a target workpiece, and confer preferred post-coating corrosion
resistance on the metal surface. There is no particular limitation
for a metal as a target workpiece, but any metals such as iron,
zinc, and aluminum may be used. Further, the chemical conversion
treatment agent according to the present embodiment is preferably
used in particular for iron-based highly high tension steel sheets
and hot-rolled steel sheets. Such an iron-based highly high tension
steel sheets and hot-rolled steel sheets are widely used in
suspension related parts of automobiles and the like. However, a
uniform chemical conversion film may be difficult to be formed on a
surface thereof due to an oxide film which may be formed on the
surface. The chemical conversion treatment agent according to the
present embodiment, which is substantially free of phosphate ions
and hazardous heavy metal ions, can form a uniform chemical
conversion film even on the surfaces of a highly high tension steel
sheet and a hot-rolled steel sheet. This can ensure good
post-coating corrosion resistance of a target workpiece.
[0021] The chemical conversion treatment agent according to the
present embodiment includes at least one (A) selected from the
group consisting of zirconium, titanium, and hafnium; at least one
(B) selected from the group consisting of an amino group-containing
silane coupling agent, hydrolysates thereof, and polymers thereof;
and fluorine (C); and a cationic urethane resin (D).
[0022] The at least one (A) selected from the group consisting of
zirconium, titanium, and hafnium corresponds to a component for
forming a chemical conversion film. Formation of a chemical
conversion film including at least one selected from the group
consisting of zirconium, titanium, and hafnium on a base material
can improve corrosion resistance and abrasion resistance of the
base material, and further can enhance adhesiveness with a coated
film.
[0023] For example, when a metal base material is surface treated
with a chemical conversion treatment agent containing zirconium,
metal ions which are eluted into the chemical conversion treatment
agent due to a dissolution reaction of metal may extract fluorine
from ZrF62-, or an interface pH may be increased. These may result
in generation of hydroxides or oxides of zirconium. These
hydroxides or oxides of zirconium are thought to be deposited on a
surface of a base material. As described above, the chemical
conversion treatment agent according to the present embodiment,
which is a reactive chemical conversion treatment agent, can be
used even for dipping treatment of a target workpiece having a
complicated shape. Moreover, surface treatment performed with the
above chemical conversion treatment agent can produce a chemical
conversion film adhering firmly on a target workpiece by virtue of
a chemical reaction. This also can allow post-treatment
water-washing to be performed.
[0024] There is no particular limitation for a source of the above
zirconium, but examples of the source include, for example, alkali
metal fluorozirconate such as K2ZrF6; fluorozirconate such as
(NH4)2ZrF6; soluble fluorozirconate such as fluorozirconate acid
such as H2ZrF6; zirconium fluoride; zirconium oxide; and the
like.
[0025] There is no particular limitation for a source of the above
titanium, but examples of the source include, for example,
fluorotitanate such as alkali metal fluorotitanate, (NH4)2TiF6;
soluble fluorotitanate such as fluorotitanate acid such as H2TiF6;
titanium fluoride; titanium oxide; and the like.
[0026] There is no particular limitation for a source of the above
hafnium, but examples of the source include, for example,
fluorohafnate acid such as H2HfF6; hafnium fluoride; and the like.
A source of the at least one selected from the group consisting of
zirconium, titanium, and hafnium is preferably a compound having at
least one selected from the group consisting of ZrF62-, TiF62-, and
HfF62- in view of high film-forming capability.
[0027] The total content of the at least one selected from the
group consisting of zirconium, titanium, and hafnium included in
the chemical conversion treatment agent according to the present
embodiment is preferably within a range between a lower limit of 20
ppm by mass and an upper limit of 10000 ppm by mass in terms of
metal. When the amount is less than 20 ppm by mass, the resulting
chemical conversion film may have insufficient performance. On the
other hand an amount of more than 10000 ppm by mass can not provide
additional effects, and is thus economically disadvantageous. The
above lower limit is more preferably 50 ppm by mass, and even more
preferably 100 ppm by mass. The above upper limit is more
preferably 2000 ppm by mass, and even more preferably 500 ppm by
mass.
[0028] The at least one (B) selected from the group consisting of
an amino group-containing silane coupling agent, hydrolysates
thereof, and polymers thereof is a compound having at least one
amino group in a molecule thereof and also having a siloxane bond.
The above at least one (B) selected from the group consisting of an
amino group-containing silane coupling agent, hydrolysates thereof,
and polymers thereof can interact with both a chemical conversion
film and a coated film. This can improve adhesiveness between
them.
[0029] This effect can be obtained presumably because a group which
can undergo hydrolysis to produce silanol is hydrolyzed and
adsorbed on a surface of a metal base material via hydrogen bond,
and an amino group can act to enhance adhesiveness between a
chemical conversion film and a metal base material. As described
above, the at least one (B) selected from the group consisting of
an amino group-containing silane coupling agent, hydrolysates
thereof, and polymers thereof is thought to act on both a metal
base material and a coated film to show an effect of improving
mutual adhesiveness.
[0030] There is no particular limitation for the above amino
group-containing silane coupling agent, but examples thereof can
include, for example, publicly known silane coupling agents such as
N-2(aminoethyl)3-aminopropylmethyldimethoxysilane,
N-2(aminoethyl)3-aminopropyltrimethoxysilane,
N-2(aminoethyl)3-aminopropyltriethoxysilane,
3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,
3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine,
N-phenyl-3-aminopropyltrimethoxysilane,
N,N-bis[(3-(trimethoxysilyl)propyl)]ethylenediamine, and the like.
Commercially available amino group-containing silane coupling
agents KBM-602, KBM-603, KBE-603, KBM-903, KBE-9103, KBM-573
(Shin-Etsu Chemical Co., Ltd.), XS1003 (Chisso Corp.), and the like
may also be used.
[0031] Hydrolysates of the above amino group-containing silane
coupling agent can be prepared by conventionally known methods, for
example, by a method including dissolving the above amino
group-containing silane coupling agent in ion-exchanged water, and
adjusting it to be acidic with any acid, and the like. As a
hydrolysate of the above amino group-containing silane coupling
agent, a commercially available product such as KBP-90 (Shin-Etsu
Chemical Co., Ltd., Active ingredient: 32%) may also be used.
[0032] There is no particular limitation for a polymer of the above
amino group-containing silane coupling agent, but examples thereof
can include, for example, commercially available products such as
Sila-Ace S-330 (.gamma.-aminopropyltriethoxysilane; Chisso Corp.),
Sila-Ace S-320 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane;
Chisso Corp.).
[0033] The total blending amount of the at least one (B) selected
from the group consisting of an amino group-containing silane
coupling agent, hydrolysates thereof, and polymers thereof in the
chemical conversion treatment agent according to the present
embodiment is preferably within a range between a lower limit of 5
ppm by mass and an upper limit of 5000 ppm by mass in terms of the
solid content concentration. An amount of less than 5 ppm by mass
can not provide sufficient coating adhesiveness. An amount of more
than 5000 ppm by mass can not provide additional effects, and is
thus economically disadvantageous. The above lower limit is more
preferably 10 ppm by mass, and even more preferably 50 ppm by mass.
The above upper limit is more preferably 1000 ppm by mass, and even
more preferably 500 ppm by mass.
[0034] Fluorine (C) can serve as an etching agent for a base
material. There is no particular limitation for a source of
fluorine (C), but examples of the source can include, for example,
fluorides such as hydrofluoric acid, ammonium fluoride, fluoroboric
acid, ammonium hydrogen fluoride, sodium fluoride, and sodium
hydrogenfluoride. Further, complex fluorides include, for example,
hexafluorosilicate, and specific examples thereof can include
hydrosilicofluoric acid, zinc hydrofluorosilicate, manganese
hydrofluorosilicate, magnesium hydrofluorosilicate, nickel
hydrofluorosilicate, iron hydrofluorosilicate, calcium
hydrofluorosilicate, and the like.
[0035] The cationic urethane resin (D) will form a uniform chemical
conversion film on a metal surface as a target workpiece. The
cationic urethane resin (D) has a cationic functional group.
Cationic functional groups include, for example, an amino group, an
ammonium group, a methylamino group, an ethylamino group, a
dimethylamino group, a diethylamino group, a trimethylamino group,
a triethylamino group, and the like. Among these, prepared is a
quaternary ammonium group. Moreover, there is no particular
limitation for a polyol, isocyanate components of a urethane resin
of the cationic urethane resin (D), and a method of polymerization,
but conventionally known components and methods may be used. As the
cationic urethane resin (D), the followings may be used: for
example, commercially available products such as F2667D (DKS Co.
Ltd., Effective concentration: 25%), Superflex 620 (DKS Co. Ltd.,
Effective concentration: 30%), and Superflex 650 (DKS Co. Ltd.,
Effective concentration: 26%).
[0036] Inclusion of the cationic urethane resin (D) alone in a
chemical conversion treatment agent can not provide preferred
effects such as post-coating corrosion resistance. However, when it
is included in a chemical conversion treatment agent in combination
with the at least one (B) selected from the group consisting of an
amino group-containing silane coupling agent, hydrolysates thereof,
and polymers thereof, a uniform chemical conversion film can be
formed on a surface of a metal surface as a target workpiece,
ensuring a preferred post-coating anticorrosion properties of that
metal member as a target workpiece. Further, the cationic urethane
resin (D) does not undergo a competing reaction with the at least
one (B) selected from the group consisting of an amino
group-containing silane coupling agent, hydrolysates thereof, and
polymers thereof, and thus may be preferably used without
inhibiting the functionality of the amino group-containing silane
coupling agent, hydrolysates thereof, and polymers thereof (B).
[0037] The blending amount of the cationic urethane resin (D) in
the chemical conversion treatment agent according to the present
embodiment is preferably within a range between a lower limit of 5
ppm by mass and an upper limit of 5000 ppm by mass in terms of the
solid content concentration. An amount of less than 5 ppm by mass
can not provide sufficient coating adhesiveness. An amount of more
than 5000 ppm by mass can not provide additional effects, and is
thus economically disadvantageous. The above lower limit is more
preferably 10 ppm by mass, and even more preferably 50 ppm by mass.
The above upper limit is more preferably 1000 ppm by mass, and even
more preferably 500 ppm by mass.
[0038] In the chemical conversion treatment agent according to the
present embodiment, the mass ratio ((B)/(D)) of the at least one
(B) selected from the group consisting of an amino group-containing
silane coupling agent, hydrolysates thereof, and polymers thereof
to the cationic urethane resin (D) is preferably 0.0002 to 5000. A
mass ratio ((B)/(D)) falling within the above range can achieve
preferred post-coating corrosion resistance of a target workpiece
on which a chemical conversion film is formed. The mass ratio
((B)/(D)) is more preferably 0.01 to 100, and even more preferably
0.5 to 2.
[0039] Preferably, the chemical conversion treatment agent
according to the present embodiment is substantially free of
phosphate ions. The phrase "substantially free of phosphate ions"
means that phosphate ions may be included in an amount such that
they do not function as a component of a chemical conversion
treatment agent. The chemical conversion treatment agent used in
the present embodiment is substantially free of phosphate ions.
Therefore, essentially no phosphorus is used which is potentially
responsible for increased environmental burden. Further, generation
of sludge such as iron phosphate and zinc phosphate can be
prevented, which otherwise may be generated when a zinc
phosphate-based treatment agent is used.
[0040] The chemical conversion treatment agent according to the
present embodiment preferably has a pH falling within a range
between a lower limit of 1.5 and an upper limit of 6.5. A pH of
lower than 1.5 may result in excessive etching, and a sufficient
film can not be formed. A pH of more than 6.5 may result in
insufficient etching, and can not provide a good film. The above
lower limit is more preferably 2.0, and the above upper limit is
more preferably 5.5. The above lower limit is even more preferably
2.5, and the above upper limit is even more preferably 5.0. In
order to adjust a pH of the chemical conversion treatment agent
according to the present embodiment, an acidic compound such as
nitric acid and sulfuric acid and a basic compound such as sodium
hydroxide, potassium hydroxide, and ammonia may be used.
[0041] Preferably, the chemical conversion treatment agent
according to the present embodiment further includes at least one
selected from the group consisting of magnesium ions, zinc ions,
calcium ions, aluminum ions, gallium ions, indium ions, and copper
ions as an adhesiveness and corrosion resistance-conferring agent.
Inclusion of the above adhesiveness and corrosion
resistance-conferring agent can provide a chemical conversion film
having better adhesiveness and corrosion resistance.
[0042] The content of the above at least one selected from the
group consisting of magnesium ions, zinc ions, calcium ions,
aluminum ions, gallium ions, indium ions, and copper ions is
preferably within a range between a lower limit of 1 ppm by mass
and an upper limit of 5000 ppm by mass. When the above content is
less than the above lower limit, sufficient effects can not be
obtained. This is not preferred. When the above content is more
than the above upper limit, additional effects can not be obtained.
This is economically disadvantageous, and may also decrease
post-coating adhesiveness. The above lower limit is more preferably
25 ppm by mass, and the above upper limit is more preferably 3000
ppm by mass.
[0043] The above chemical conversion treatment agent may be used in
combination with any component in addition to the above components,
if needed. Components which can be used can include silica and the
like. It is possible to increase post-coating corrosion resistance
by adding such a component.
[0044] <Pre-Coating Treatment Method>
There is no particular limitation for chemical conversion in the
pre-coating treatment method according to the present embodiment,
but it may be performed by contacting a chemical conversion
treatment agent with a metal surface under common treatment
conditions. The treatment temperature upon the above chemical
conversion is preferably within a range between a lower limit of
20.degree. C. and an upper limit of 70.degree. C. The above lower
limit is more preferably 30.degree. C., and the above upper limit
is more preferably 50.degree. C. The chemical conversion time for
the above chemical conversion is preferably within a range between
a lower limit of 5 seconds and an upper limit of 1200 seconds. The
above lower limit is more preferably 30 seconds, and the above
upper limit is more preferably 120 seconds. There is no particular
limitation for a method of conversion treatment, but examples
thereof can include, for example, the dipping method, the spray
method, the roll coating method, and the like.
[0045] In the pre-coating treatment method according to the present
embodiment, it is preferred that a metal surface may be subjected
to degreasing treatment, post-degreasing water-washing treatment
before performing the above chemical conversion, and subjected to
post-chemical conversion waster-washing treatment after the above
chemical conversion. The above degreasing treatment may be
performed in order to remove oils and stains adhering on a surface
of a base material, and usually performed by dipping treatment at
30 to 55.degree. C. for about several minutes with a degreaser such
as phosphorus-free/nitrogen-free degreasing wash liquid.
Preliminary degreasing treatment may be performed, if needed, prior
to degreasing treatment.
[0046] The above post-degreasing water-washing treatment may be
conducted by performing spray treatment using a large amount of
wash water once or more times in order to wash out a degreaser with
water after degreasing treatment. The above post-chemical
conversion water-washing treatment may be performed once or more
times in order to avoid negative effects on adhesiveness, corrosion
resistance, and the like after various subsequent coatings. In that
case, the final water-washing is properly performed with pure
water. In this post-chemical conversion water-washing treatment,
water washing may be performed by either one of spray water-washing
or dip water-washing or in combination of these. After the above
post-chemical conversion water-washing treatment, drying may be
performed in accordance with a known method, if needed, and then
various coatings may be applied.
[0047] The pre-coating treatment method according to the present
embodiment does not require surface conditioning treatment which is
required in a conventionally used practical method involving
treatment with a zinc phosphate-based chemical conversion treatment
agent. This enables chemical conversion of a metal base material to
be performed in fewer steps.
[0048] There is no particular limitation for a metal base material
used in the present embodiment, but examples thereof can include
iron-based base materials, aluminum-based base materials, and
zinc-based base materials. Iron-, aluminum-, and zinc-based base
materials mean an iron-based base material in which the base
material includes iron and/or an alloy thereof, an aluminum-based
base material in which the base material includes aluminum and/or
an alloy thereof, and a zinc-based base material in which the base
material includes zinc and/or an alloy thereof, respectively.
[0049] Further, the pre-coating treatment method according to the
present embodiment is preferably used in particular for an
iron-based highly high tension steel sheet and hot-rolled steel
sheet. An oxide film having fine surface unevenness may be formed
on a hot-rolled steel sheet, and the oxide film is also of a porous
state in which a large number of pores are present. For this
reason, the surface is very difficult to be covered with a uniform
chemical conversion film. An ununiform chemical conversion film
formed on a surface may cause different potentials between a coated
portion and an uncoated portion, preventing formation of a uniform
electrodeposition coated film upon electrodeposition coating.
Consequently, a pre-coating treatment method using a conventional
chemical conversion treatment agent including zirconium and others
can not ensure post-coating corrosion resistance comparable to that
in a case where a zinc phosphate-based chemical conversion
treatment agent. Similarly, an oxide film having fine surface
unevenness may also be formed on a highly high tension steel sheet,
and a large amount of dissimilar metals may also be included in the
highly high tension steel sheet. These may cause the above
different potentials to be more significant, resulting in even less
uniform covering with a chemical conversion film. Therefore,
ensuring post-coating corrosion resistance may be more difficult.
However, the pre-coating treatment method according to the present
embodiment can form a uniform chemical conversion film even on an
iron-based highly high tension steel sheet and hot-rolled steel
sheet, and can ensure post-coating corrosion resistance comparable
to that in a case where a phosphate ion-containing chemical
conversion treatment agent is used. The mechanism by which such an
effect can be obtained is not clearly understood. Nonetheless, one
possibility is that the cationic urethane resin (D) may
preferentially cover depressed portions and pores of an oxide film
through the interaction between the cationic groups of the cationic
urethane resin (D) included in a chemical conversion treatment
agent and a surface of a steel sheet.
[0050] The film content of a chemical conversion film obtained by
the pre-coating treatment method according to the present
embodiment is preferably within a range between a lower limit of
0.1 mg/m2 and an upper limit of 500 mg/m2 in terms of the total
amount of metal included in a chemical conversion treatment agent.
An amount of less than 0.1 mg/m2 can not provide a uniform chemical
conversion film, and is thus not preferred. An amount of more than
500 mg/m2 can not provide additional effects, and is thus
economically disadvantageous. The above lower limit is more
preferably 5 mg/m2, and the above upper limit is more preferably
200 mg/m2.
[0051] <Metal Member>
A metal base material treated by the above pre-coating treatment
method may be subjected to laser processing, press working, and the
like to obtain a metal member formed and processed depending on
various purposes. Alternatively, a pre-formed and processed metal
member may be subjected to the above pre-coating treatment method.
There is no particular limitation for the applications of a metal
member according to the present embodiment, but examples of thereof
include metal members of automobiles such as a door, a bonnet, a
roof, a hood, a fender, a trunk room, and the like. Further, they
also include metal members used for motorcycles, buses, bicycles,
and the like. A metal member treated by the pre-coating treatment
method according to the present embodiment may preferably be used
in those applications as described above in which a high level of
post-coating corrosion resistance is required in view of safely and
aesthetics.
[0052] There is no particular limitation for coating which can be
performed on a metal member treated by the above pre-coating
treatment method, but coating may be performed with a
conventionally known coating material such as a cationic
electrodeposition coating material, a solvent coating material, a
water-based coating material, and a powder coating material. For
example, there is no particular limitation for the above cationic
electrodeposition coating material, but a conventionally known
cationic electrodeposition coating material including an aminated
epoxy resin, aminated acrylic resin, a sulfonated epoxy resin, and
the like may be applied. Amount these, a cationic electrodeposition
coating material including a resin having a functional group which
shows reactivity or compatibility with an amino group is preferred
in order to enhance adhesiveness between an electrodeposition
coated film and a chemical conversion film, considering that at
least one selected from the group consisting of an amino
group-containing silane coupling agent, hydrolysates thereof, and
polymers thereof is blended in a chemical conversion treatment
agent.
[0053] The present invention shall not be limited to the above
embodiments. Modifications, improvements, and the like can be made
within a scope of the present invention as long as an effect of the
present invention can be achieved.
EXAMPLES
[0054] Next, the present invention will be described in more detail
with reference to Examples, but the present invention shall not be
limited to these Examples. It is noted that the term "ppm" as used
in Examples and Comparative Examples refers to "ppm by mass."
Example 1
[0055] A commercially available cold-rolled steel plate (SPC 270,
Nippon Testpanel Co., Ltd., 70 mm.times.150 mm.times.0.8 mm) as a
base material was subjected to pre-coating treatment under the
following conditions.
(1) Pre-Coating Treatment
[0056] Degreasing treatment: Dipping treatment was performed at
40.degree. C. with 2% by mass of "Surfcleaner 53" (a degreaser from
Nippon Paint Surf Chemicals Co., Ltd.). Post-degreasing
water-washing treatment: Spray treatment was performed with tap
water for 30 seconds. Chemical conversion treatment: Zircon
hydrofluoric acid and KBM-603
(N-2(aminoethyl)3-aminopropyltrimethoxysilane, Effective
concentration: 100%, Shin-Etsu Chemical Co., Ltd.) as an amino
group-containing silane coupling agent; and F2667D (DKS Co. Ltd.,
Effective concentration: 25%) as a cationic urethane resin were
used to prepare a chemical conversion treatment agent including
zirconium (A) in a concentration of 100 ppm by mass, an amino
group-containing silane coupling agent (B) in a concentration of
100 ppm by mass in terms of the solid content, and a cationic
urethane resin (D) in a concentration of 100 ppm by mass. Sodium
hydroxide was used to adjusted pH to 4. The temperature of the
chemical conversion treatment agent was adjusted to 40.degree. C.,
and a base material was dip-treated for 60 seconds. The film amount
in the initial stage of the treatment was 13.4 mg/m2.
[0057] Post-chemical conversion water-washing treatment: Spray
treatment was performed with tap water for 30 seconds. Further,
spray treatment was performed with ion-exchanged water for 10
seconds. Then, electrodeposition coating was performed in a wet
condition. A cold-rolled steel sheet after water washing was dried
at 80.degree. C. for 5 minutes in an electric drying furnace, and
then the film amount was analyzed as the total amount of metal
contained in a chemical conversion treatment agent with a "ZSX
PrimusII" (an X-ray analyzer from Rigaku Corporation).
(2) Coating
[0058] A cold-rolled steel plate was treated with a chemical
conversion treatment agent at 1 L per m2, and then
electrodeposition-coated with "Powernics 310" (a cationic
electrodeposition coating material from Nipponpaint Industrial
Coatings Co., Ltd.) so as to obtain a dry coating thickness of 20
.mu.m, and washed with water, and then heated for baking at
170.degree. C. for 20 minutes to obtain a test plate.
Examples 2 to 7
[0059] Test plates were prepared as in Example 1 except that the
metal base material was changed to a cold-rolled steel plate (SPC
780 from Nippon Testpanel Co., Ltd., 70 mm.times.150 mm.times.0.8
mm), hot-rolled steel plates (SPH 270, SPH 440, SPH 590 from Nippon
Testpanel Co., Ltd., 70 mm.times.150 mm.times.0.8 mm), a zinc-based
plated steel sheet (GA 270 from Nippon Testpanel Co., Ltd., 70
mm.times.150 mm.times.0.8 mm), or a 6000-series aluminum plate
(Nippon Testpanel Co., Ltd., 70 mm.times.150 mm.times.0.8 mm). It
is noted that the types of base materials shown in Tables 1 and 2
are as follows: SPC represents the above cold-rolled steel plate;
and SPH represents the above hot-rolled steel plates; and GA
represents the above zinc-based plated steel sheet; and AL
represents the above 6000-series aluminum plate.
Examples 8 to 13
[0060] Test plates were prepared as in Example 1 except that the
above cold rolled steel plate or hot-rolled steel plates were used
as a metal base material, and the concentrations of the silane
coupling agent (B) and the cationic urethane resin (D) were 1 ppm
by mass, 5 ppm by masses, and 50 ppm by masses, respectively as
shown in Table 1.
Examples 14 and 15
[0061] Test plates were prepared as in Example 1 except that the
above hot-rolled steel plates were used as a metal base material,
and Superflex 620 (DKS Co. Ltd., Effective concentration: 30%) or
Superflex 650 (DKS Co. Ltd., Effective concentration: 26%) was used
as the cationic urethane resin (D) as shown in Table 1.
Examples 16 to 21
[0062] Test plates were prepared as in Example 1 except that the
above cold rolled steel plate or hot-rolled steel plates were used
as a metal base material, and KBM-603
(N-2(aminoethyl)3-aminopropyltrimethoxysilane, effective
concentration 100%, Shin-Etsu Chemical Co., Ltd.) or KBM-903
(3-aminopropyltrimethoxysilane, effective concentration: 100%,
Shin-Etsu Chemical Co., Ltd.) was used as the silane coupling agent
(B) as shown in Table 1, and the concentrations of the silane
coupling agent (B) and the cationic urethane resin (D) were as
shown in Table 1.
Examples 22 to 25
[0063] Test plates were prepared as in Example 1 except that the
concentration of zirconium (A) was 500 ppm by masses, and the above
cold-rolled steel plate or hot-rolled steel plates were used as a
metal base material, and KBE-903 (3-aminopropyltriethoxysilane,
effective concentration: 100%, Shin-Etsu Chemical Co., Ltd. or
XS1003 (N,N-bis[(3-(trimethoxysilyl)propyl)]ethylenediamine,
effective concentration: 50%, Nichibitrading Co., Ltd., Inc.) was
used as the silane coupling agent (B) as shown in Table 1, and the
concentrations of the silane coupling agent (B) and the cationic
urethane resin (D) were as shown in Table 1.
Examples 26 to 37
[0064] Test plates were prepared as in Example 1 except that the
above cold rolled steel plate or hot-rolled steel plates were used
as a metal base material, and zinc nitrate (Zn) was used as an
adhesiveness and corrosion-resistance conferring material shown in
Tables 1 and 2, and the concentrations of zirconium (A), the silane
coupling agent (B), and the cationic urethane resin (D) were as
shown in Tables 1 and 2.
Examples 38 to 41
[0065] Test plates were prepared as in Example 1 except that the
above cold rolled steel plate or hot-rolled steel plates were used
as a metal base material as shown in Table 2, and the
concentrations of the silane coupling agent (B) and the cationic
urethane resin (D) were as shown in Table 2.
Comparative Examples 1 to 8
[0066] Test plates were prepared as in Example 1 except that the
above cold rolled steel plate or hot-rolled steel plates were used
as a metal base material as shown in Table 2, and the concentration
of the silane coupling agent (B) or the cationic urethane resin (D)
was as shown in Table 2.
Reference Example 1
[0067] A test plate was prepared as in Example 1 except that a
chemical conversion treatment agent was prepared without including
the cationic urethane resin (D) in the chemical conversion
treatment agent.
Reference Examples 2 and 3
[0068] Test plates were prepared as in Example 1 except that the
above cold rolled steel plate or hot-rolled steel plates were used
as a metal base material, and surface conditioning was performed
with Surffine GL1 (Nippon Paint Surf Chemicals Co., Ltd.) at room
temperature for 30 seconds after post-degreasing water-washing
treatment, and then chemical conversion treatment was performed by
dipping treatment using Surfdine SD-6350 (a zinc phosphate-based
chemical conversion treatment agent from Nippon Paint Surf
Chemicals Co., Ltd.) at 35.degree. C. for 2 minutes instead of
using the above chemical conversion treatment agents as shown in
Table 2.
[0069] The following evaluation tests were performed for the test
plates obtained as described above from Examples 1 to 41,
Comparative Examples 1 to 8, and Reference Examples 1 to 3.
[0070] [Secondary Adhesiveness tests (SDT)] The resulting test
plates were each nicked deep enough to reach an underlying material
along two parallel and longitudinal lines, and then dipped under a
5% NaCl aqueous solution at 50.degree. C. for 480 hours.
Subsequently, a cut portion was exfoliated off with a tape, and the
exfoliation state of a coating material was observed. The
exfoliation state was evaluated in accordance with the following
evaluation criteria, and an evaluation score of 2 or more was
considered as acceptable. The results were shown in Tables 1 and
2.
1: Not exfoliated 2: Somewhat exfoliated 3: Exfoliation width is 3
mm or more
[0071] [Salt-water spray tests (SST)] The resulting test plates
were each cross-cut deep enough to reach an underlying material,
and continuously sprayed with a 5% NaCl aqueous solution for 240
hours in a salt-water spry test chamber maintained at 35.degree. C.
Subsequently, the width of a blister from a cut portion was
measured. Those having a blister width comparable to or less than
that in a case where a zinc phosphate-based surface treatment agent
was used as shown in Reference Examples 2, 3 were considered as
acceptable. The results were shown in Tables 1 and 2.
[0072] [Combined cyclic corrosion tests (CCT)] The resulting test
plates were each cross-cut deep enough to reach an underlying
material, and then combined cyclic corrosion tests were performed.
Combined tests were performed for 100 cycles by a test method in
accordance with JASO M609-91. After the tests, the width of a
blister from a cut portion was measured. Those having a blister
width comparable to or less than that in a case where a zinc
phosphate-based surface treatment agent was used as shown in
Reference Examples 2, 3 were considered as acceptable. The results
were shown in Tables 1 and 2.
TABLE-US-00001 TABLE 1 Silane Cationic Adhesiveness and coupling
urethane corrosion- agent(B) resin(D) resistance Silane Silane
Zirconium conferring agent coupling coupling concentration(A)
Concentration agent agent (ppm) Types (ppm) Types (ppm) Types (ppm)
Examples 1 100 None 0 KBM-603 100 F2667D 100 2 100 None 0 KBM-603
100 100 3 100 None 0 KBM-603 100 100 4 100 None 0 KBM-603 100 100 5
100 None 0 KBM-603 100 100 6 100 None 0 KBM-603 100 100 7 100 None
0 KBM-603 100 100 8 100 None 0 KBM-603 1 1 9 100 None 0 KBM-603 1 1
10 100 None 0 KBM-603 5 5 11 100 None 0 KBM-603 5 5 12 100 None 0
KBM-603 50 50 13 100 None 0 KBM-603 50 50 14 100 None 0 KBM-603 100
Superflex 100 620 15 100 None 0 KBM-603 100 Superflex 100 650 16
100 None 0 KBM-603 1 F2667D 5000 17 100 None 0 KBM-603 1 5000 18
100 None 0 KBM-903 5000 1 19 100 None 0 KBM-903 5000 1 20 100 None
0 KBM-603 5000 5000 21 100 None 0 KBM-603 5000 5000 22 500 None 0
.chi.S-1003 100 100 23 500 None 0 XS-1003 100 100 24 500 None 0
KBE-903 5000 5000 25 500 None 0 KBE-903 5000 5000 26 100 Zn 500
KBM-603 100 100 27 100 Zn 500 KBM-603 100 100 28 20 Zn 500 KBM-603
400 400 Film Base amount SST CCT ((B)/(D)) material (mg/m.sup.2)
Coating SDT (mm) (mm) Examples 1 1 SPC270 13.4 Powernics1010F 1 1.5
6.9 2 1 SPC780 26.6 1 1.7 7.3 3 1 SPH270 17.6 1 1.7 5.1 4 1 SPH440
21.8 1 2.0 7.2 5 1 SPH590 25.3 1 1.9 9.9 6 1 GA270 15.5 1 0.8 0.3 7
1 AL(6000series) 10.2 1 0.2 0.2 8 1 SPC270 23.4 2 1.8 8.7 9 1
SPH270 25.5 2 2.1 9.9 10 1 SPC270 19.3 2 2.0 8.9 11 1 SPH270 22.2 2
2.2 9.2 12 1 SPC270 14.7 1 1.8 7.3 13 1 SPH270 16.2 1 1.6 6.5 14 1
SPH270 15.9 1 2.0 7.4 15 1 SPH270 18.4 1 2.2 7.6 16 0.0002 SPC270
13.4 1 1.5 7.0 17 0.0002 SPH270 16.9 1 1.6 5.3 18 5000 SPC270 11.1
1 1.4 6.8 19 5000 SPH270 16.8 1 1.5 5.8 20 1 SPC270 9.5 1 1.8 8.3
21 1 SPH270 10.1 1 1.7 7.2 22 1 SPC270 38.5 1 1.5 6.8 23 1 SPH270
40.8 1 1.6 5.0 24 1 SPC270 10.5 1 1.4 7.4 25 1 SPH270 15.3 1 1.5
6.6 26 1 SPC270 13.6 1 1.3 5.3 27 1 SPH270 17.2 1 1.3 4.9 28 1
SPC270 10.3 1 1.8 6.9
TABLE-US-00002 TABLE 2 Silane Cationic Adhesiveness and coupling
urethane corrosion- agent(B) resin(D) resistance Solid Solid
Zirconium conferring agent content content concentra- Concen-
concen- concen- Film tion(A) tration tration tration ((B)/ Base
amount SST CCT (ppm) Types (ppm) Types (ppm) Types (ppm) (D))
material (mg/m.sup.2) Coating SDT (mm) (mm) Exam- 29 20 Zn 500
KBM-603 400 F2667D 400 1 SPH270 11.2 Powernics 1 1.9 7.1 ples 30
10000 Zn 500 KBM-603 400 400 1 SPC270 18.4 310 1 2.2 8.3 31 10000
Zn 500 KBM-603 400 400 1 SPH270 20.3 1 2.1 8.8 32 200 Zn 500
KBM-603 400 400 1 SPC270 15.2 1 1.3 4.7 33 200 Zn 500 KBM-603 400
400 1 SPH270 19.7 1 1.6 4.5 34 200 Zn 500 KBM-603 200 400 0.5
SPC270 16.8 1 0.9 4.9 35 200 Zn 500 KBM-603 200 400 0.5 SPH270 21.2
1 0.9 5.0 36 200 Zn 500 KBM-603 400 200 2 SPC270 15.5 1 1.3 4.9 37
200 Zn 500 KBM-603 400 200 2 SPH270 20.2 1 0.9 5.0 38 100 None 0
KBM-603 1 100 0.01 SPC270 15.6 2 2.1 8.8 39 100 None 0 KBM-603 1
100 0.01 SPH270 16.3 2 2.0 9.1 40 100 None 0 KBM-603 100 1 100
SPC270 16.2 1 2.1 7.1 41 100 None 0 KBM-603 100 1 100 SPH270 17.8 1
2.0 11.0 Compar- 1 100 None 0 KBM-603 0 F2667D 100 -- SPC270 22.7
Powernics 3 2.1 10.5 ative 2 100 None 0 KBM-603 0 100 -- SPC780
28.5 310 3 2.3 11.9 Exam- 3 100 None 0 KBM-603 0 100 -- SPH270 26.4
3 2.4 11.9 ples 4 100 None 0 KBM-603 0 100 -- SPH440 30.3 3 2.2
15.3 5 100 None 0 KBM-603 0 100 -- SPH590 34.1 3 2.5 14.2 6 100
None 0 KBM-603 100 0 -- SPH270 21.4 1 2.0 13.5 7 100 None 0 KBM-603
0 5000 -- SPC270 18.7 3 1.9 10.1 8 100 None 0 KBM-603 0 5000 --
SPH270 22.1 3 2.0 14.3 Reference 1 100 None 0 KBM-603 100 F2667D 0
-- SPC270 18.7 Powernics 1 2.0 7.1 Example 2 Zinc phosphate
treatment SPC270 2100 310 2 2.3 9.2 3 SPH270 2500 2 2.5 11.3
[0073] Comparison of Examples 1 to 41 with Comparative Examples 1
to 5, 7, and 8 shows that the metal base materials treated by the
chemical conversion treatment agents from Examples 1 to 41 have
superior secondary adhesiveness (SDT) as compared with the metal
base materials treated by the chemical conversion treatment agents
from Comparative Examples 1 to 5, 7, and 8. These results
demonstrate that inclusion of the at least one (B) selected from
the group consisting of an amino group-containing silane coupling
agent, hydrolysates thereof, and polymers thereof in a chemical
conversion treatment agent can confer preferred post-coating
corrosion resistance on a metal base material treated by the
chemical conversion treatment agent. Further, neither the metal
base materials treated with the chemical conversion treatment
agents from Comparative Examples 1 and 3 nor the metal base
materials treated with the chemical conversion treatment agents
from Comparative Examples 7 and 8 show preferred secondary
adhesiveness (SDT). This indicates that an increased content of the
cationic urethane resin (D) can not provide preferred results when
a chemical conversion treatment agent does not contain the at least
one (B) selected from the group consisting of an amino
group-containing silane coupling agent, hydrolysates thereof, and
polymers thereof, and also indicates that preferred post-coating
corrosion resistance can be conferred on a metal base material by
pre-coating treatment of the metal base material with a chemical
conversion treatment agent including the at least one (B) selected
from the group consisting of an amino group-containing silane
coupling agent, hydrolysates thereof, and polymers thereof in
combination with the cationic urethane resin (D).
[0074] Comparison of Examples 1 to 41 with Comparative Example 6
shows that the metal base materials treated with the chemical
conversion treatment agents from Examples 1 to 41 have superior
results from the combined cyclic corrosion tests (CCT) as compared
with the metal base material treated with the chemical conversion
treatment agent from Comparative Example 6. These results indicate
that inclusion of the cationic urethane resin (D) in a chemical
conversion treatment agent can confer preferred post-coating
corrosion resistance on a metal base material treated with the
chemical conversion treatment agent.
[0075] Comparison of Examples 1 to 41 with Reference Examples 1 to
3 shows that the metal base materials treated with the chemical
conversion treatment agents from Examples 1 to 41 have comparable
or superior results from the salt-water spray tests (SST), the
combined cyclic corrosion tests (CCT) as compared with the metal
base materials treated with the chemical conversion treatment
agents from Reference Examples 1 to 3. These results indicate that
the metal base materials treated with the chemical conversion
treatment agents according to the embodiments of the present
invention have comparable or superior post-coating corrosion
resistance as compared with the metal base material treated by the
conventional pre-coating treatment method used for a cold-rolled
steel plate from the reference example 1 and the metal base
materials subjected to the conventional zinc phosphate treatment
from Reference Examples 2 to 3.
[0076] Further, comparison of Examples 1 to 7 shows that the metal
base materials treated with the chemical conversion treatment
agents from Examples 1 to 7 each have preferred post-coating
corrosion resistance. These results indicate that the chemical
conversion treatment agents according to the embodiments of the
present invention can unsure excellent post-coating corrosion
resistance regardless of the types of treatment targets.
* * * * *