U.S. patent application number 12/497159 was filed with the patent office on 2010-02-18 for chemical conversion coating agent and surface-treated metal.
This patent application is currently assigned to Nippon Paint Co., Ltd.. Invention is credited to Kazuhiro Makino, Masahiko Matsukawa, Toshiaki Shimakura.
Application Number | 20100038250 12/497159 |
Document ID | / |
Family ID | 32475632 |
Filed Date | 2010-02-18 |
United States Patent
Application |
20100038250 |
Kind Code |
A1 |
Matsukawa; Masahiko ; et
al. |
February 18, 2010 |
CHEMICAL CONVERSION COATING AGENT AND SURFACE-TREATED METAL
Abstract
It is an object of the present invention to provide a chemical
conversion coating agent containing no chromium and capable of
applying good chemical conversion treatment which is equal to or
more than chemical conversion treatment by zinc phosphate to all
metals such as iron, zinc and aluminum. A chemical conversion
coating agent comprising: at least one kind selected from the group
consisting of zirconium, titanium and hafnium; fluorine; and a
water-soluble epoxy compound containing an isocyanate group and/or
a melamine group, wherein a content of the at least one kind
selected from the group consisting of zirconium, titanium and
hafnium in the chemical conversion coating agent is 20 to 10000 ppm
in terms of metal, and a content of the water-soluble epoxy
compound containing the isocyanate group and/or the melamine group
in the chemical conversion coating agent is 5 to 5000 ppm as a
concentration of solid matter.
Inventors: |
Matsukawa; Masahiko;
(Nishitokyo-shi, JP) ; Makino; Kazuhiro;
(Yokohama-shi, JP) ; Shimakura; Toshiaki;
(Ichikawa-shi, JP) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
1875 EYE STREET, N.W., SUITE 1100
WASHINGTON
DC
20006
US
|
Assignee: |
Nippon Paint Co., Ltd.
Osaka-shi
JP
|
Family ID: |
32475632 |
Appl. No.: |
12/497159 |
Filed: |
July 2, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10743389 |
Dec 23, 2003 |
|
|
|
12497159 |
|
|
|
|
Current U.S.
Class: |
205/80 |
Current CPC
Class: |
Y10T 428/31547 20150401;
Y10T 428/31725 20150401; C23C 22/34 20130101; C23C 2222/20
20130101 |
Class at
Publication: |
205/80 |
International
Class: |
C25D 5/00 20060101
C25D005/00; C23C 22/05 20060101 C23C022/05 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 24, 2002 |
JP |
2002-372770 |
Dec 24, 2002 |
JP |
2002-372773 |
May 28, 2003 |
JP |
2003-150946 |
Dec 2, 2003 |
JP |
2003-403687 |
Claims
1. A cation electrocoating method comprising: pre-treating a
substance comprising an iron material at least in part by employing
a chemical conversion coating agent comprising at least one kind
selected from the group consisting of zirconium, titanium and
hafnium; fluorine; and an amine group-containing water-soluble
epoxy compound having an isocyanate group, wherein a content of the
at least one kind selected from the group consisting of zirconium,
titanium and hafnium in the chemical conversion coating agent is 20
to 10000 ppm in terms of metal, and the amino group-containing
water-soluble epoxy compound having an isocyanate group is obtained
by allowing an epoxy compound selected from the group consisting of
bisphenol F epichlorohydrin type epoxy compound containing an amino
group and bisphenol A epichlorohydrin type epoxy compound
containing an amino group to react with partially blocked
polyisocyanate, and a content of the amino group-containing
water-soluble epoxy compound having an isocyanate group in the
chemical conversion coating agent is 5 to 5000 ppm as a
concentration of solid matter and wherein the pH of the agent is
1.5 to 6.5; followed by water rinsing the pretreated substance and
applying a cation electrocoating.
2. The method according to claim 1 wherein the chemical conversion
coating agent further contains 1 to 5000 ppm of at least one kind
of a chemical conversion reaction accelerator selected from the
group consisting of nitrite ions, nitro group-containing compounds,
hydroxylamine sulfate, persulfate ions, sulfite ions, hyposulfite
ions, peroxides, iron (III) ions, citric acid iron compounds,
bromate ions, perchlorinate ions, chlorate ions, chlorite ions as
well as ascorbic acid, citric acid, tartaric acid, malonic acid,
succinic acid and salts thereof.
3. The method according to claim 1 wherein the chemical conversion
coating agent further contains at least one kind selected from the
group consisting of at least one kind of metal ions (A) selected
from the group consisting of zinc ions, magnesium ions, calcium
ions, aluminum ions, manganese ions and iron ions; copper ions (B);
and a silicon-containing compound (C).
4. The method according to claim 3, wherein the silicon-containing
compound (C) is at least one kind selected from the group
consisting of silica, water-soluble silicate compounds, esters of
silicic acid, alkyl silicates and silane coupling agents.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional of co-pending application
Ser. No. 10/743,389, filed on Dec. 23, 2003, and for which priority
is claimed under 35 U.S.C. .sctn.120; and this application claims
priority of Application No. 2002-372770 filed in Japan on Dec. 24,
2002 under 35 U.S.C. .sctn.119; Application No. 2002-372773 filed
in Japan on Dec. 24, 2002 under 35 U.S.C. .sctn.119; Application
No. 2003-150946 filed in Japan on May 28, 2003 under 35 U.S.C.
.sctn.119; and Application No. 2003-403687 filed in Japan on Dec.
2, 2003 under 35 U.S.C. .sctn.119; the entire contents of all are
hereby incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to a chemical conversion
coating agent and a surface-treated metal.
BACKGROUND ART
[0003] When a cationic electrocoating or a powder coating is
applied to the surface of a metal material, a chemical conversion
treatment is generally applied in order to improve the properties
such as corrosion resistance and adhesion to a coating film. With
respect to a chromate treatment used in the chemical conversion
treatment, from the viewpoint of being able to further improve the
adhesion to a coating film and the corrosion resistance, in recent
years, a harmful effect of chromium has been pointed and the
development of a chemical conversion coating agent containing no
chromium is required. As such a chemical conversion treatment, a
treatment using zinc phosphate is widely adopted (cf. Japanese
Kokai Publication Hei-10-204649, for instance).
[0004] However, since treating agents based on zinc phosphate have
high concentrations of metal ions and acids and are very active,
these are economically disadvantageous and low in workability in a
wastewater treatment. Further, there is a problem of formation and
precipitation of salts, being insoluble in water, associated with
the metal surface treatment using treating agents based on zinc
phosphate. Such a precipitated substance is generally referred to
as sludge and increases in cost for removal and disposal of such
sludge become problems. Further, there is also a problem that in a
metal surface treatment using treating agents based on zinc
phosphate, a surface conditioning is required; therefore, a
treatment process become long.
[0005] As a metal surface treating agent other than such a treating
agent based on zinc phosphate or a chemical conversion coating
agent of chromate, there is known a metal surface treating agent
comprising a zirconium compound (cf. Japanese Kokai Publication
Hei-07-310189, for instance). Such a metal surface treating agent
comprising a zirconium compound has an excellent property in point
of suppressing the generation of the sludge in comparison with the
treating agent based on zinc phosphate described above.
[0006] However, a chemical conversion coat attained by such a metal
surface treating agent comprising a zirconium compound is poor in
the adhesion to a coating film attained by various coating methods,
and usually less used as a pretreatment step for coating.
[0007] As a metal surface treating agent containing a zirconium
compound to improve an issue of the adhesion to a coating film
described above, a metal surface treating agent comprising a
zirconium compound, vanadium and resin has been developed (cf.
Japanese Kokai Publication 2002-60699, for instance). However,
since such a metal surface treating agent contains vanadium, it is
not preferable in point of causing a problem of a harmful effect on
human body and wastewater treatment.
[0008] In addition, the metal surface treating agent comprising a
zirconium compound is insufficient in adhesion to an iron material;
therefore, it was difficult to form a good chemical conversion coat
on the iron material. Therefore, by one step of treatment to be
applied to bodies and parts of automobiles comprising various metal
materials such as iron, zinc and aluminum, a surface treatment for
all metals cannot be performed and this agent was inefficient from
the viewpoint of workability. Accordingly, there is desired the
development of a chemical conversion coating agent containing no
chromium and capable of applying a chemical conversion treatment to
articles comprising various metal materials by one step.
SUMMARY OF THE INVENTION
[0009] In consideration of the above circumstances, it is an object
of the present invention to provide a chemical conversion coating
agent containing no chromium and capable of applying good chemical
conversion treatment which is equal to or more than chemical
conversion treatment by zinc phosphate to all metals such as iron,
zinc and aluminum.
[0010] The present invention is a chemical conversion coating agent
comprising:
[0011] at least one kind selected from the group consisting of
zirconium, titanium and hafnium;
[0012] fluorine; and
[0013] a water-soluble epoxy compound containing an isocyanate
group and/or a melamine group,
[0014] wherein a content of the at least one kind selected from the
group consisting of zirconium, titanium and hafnium in the chemical
conversion coating agent is 20 to 10000 ppm in terms of metal,
and
[0015] a content of the water-soluble epoxy compound containing the
isocyanate group and/or the melamine group in the chemical
conversion coating agent is 5 to 5000 ppm as a concentration of
solid matter.
[0016] The present invention is a chemical conversion coating agent
comprising:
[0017] at least one kind selected from the group consisting of
zirconium, titanium and hafnium;
[0018] fluorine;
[0019] a water-soluble epoxy compound; and a polyisocyanate
compound and/or a melamine resin,
[0020] wherein a content of the at least one kind selected from the
group consisting of zirconium, titanium and hafnium in the chemical
conversion coating agent is 20 to 10000 ppm in terms of metal,
and
[0021] a total amount of the water-soluble epoxy compound and the
polyisocyanate compound and/or the melamine resin in the chemical
conversion coating agent is 5 to 5000 ppm as a concentration of
solid matter.
[0022] Preferably, said water-soluble epoxy compound has an amino
group.
[0023] Preferably, said chemical conversion coating agent
contains
[0024] 1 to 5000 ppm of at least one kind of a chemical conversion
reaction accelerator selected from the group consisting of nitrite
ions, nitro group-containing compounds, hydroxylamine sulfate,
persulfate ions, sulfite ions, hyposulfite ions, peroxides, iron
(III) ions, citric acid iron compounds, bromate ions, perchlorinate
ions, chlorate ions, chlorite ions as well as ascorbic acid, citric
acid, tartaric acid, malonic acid, succinic acid and salts
thereof.
[0025] Preferably, said chemical conversion coating agent
contains
[0026] at least one kind selected from the group consisting of: at
least one kind of metal ions (A) selected from the group consisting
of zinc ions, magnesium ions, calcium ions, aluminum ions,
manganese ions and iron ions; copper ions (B); and a
silicon-containing compound (C).
[0027] Preferably, said silicon-containing compound (C) is at least
one kind selected from the group consisting of silica,
water-soluble silicate compounds, esters of silicic acid, alkyl
silicates and silane coupling agents.
[0028] Preferably, a pH of said chemical conversion coating agent
is 1.5 to 6.5.
[0029] The present invention is also a surface-treated metal having
a chemical conversion coat formed by the chemical conversion
coating agent.
[0030] Preferably, said chemical conversion coat has a coat amount
of 0.1 to 500 mg/m.sup.2 in sum of a total amount of metals
contained in the chemical conversion coating agent and carbon
contained in the water-soluble epoxy compound.
[0031] Preferably, in said surface-treated metal,
[0032] a substance to be treated comprises an iron material, a zinc
material and/or an aluminum material.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Hereinafter, the present invention will be described in
detail.
[0034] The present invention provides a chemical conversion coating
agent which contains at least one kind selected from the group
consisting of zirconium, titanium and hafnium, and fluorine, but
substantially contains no harmful heavy metal ions such as
chromium. For example, when a metal material is treated by a
zirconium-containing chemical conversion coating agent, it is
considered that hydroxide or oxide of zirconium is deposited on the
surface of the base material because metal ions elutes in the
chemical conversion coating agent through a dissolution reaction of
the metal and pH at an interface increases.
[0035] When such a chemical conversion coating agent contains an
epoxy compound, the epoxy compound chelates at least one kind
selected from the group consisting of zirconium, titanium and
hafnium. It is estimated that this chelation provides the strong
adhesion of a coat comprising the at least one kind selected from
the group consisting of zirconium, titanium and hafnium to a coat
of an epoxy compound. It is estimated that since the coat of an
epoxy compound comprises an organic component, it has a high
affinity for resin components which constitute an electrodeposition
coating film or a coating film by powder coating to be further
formed on the coat of an epoxy compound and this allows the strong
adhesion to be attained.
[0036] Since the chemical conversion coating agent of the present
invention further contains components which act as a curing agent,
crosslinking reaction occurs in the above coat of an epoxy
compound; thereby, it is possible to form an organic coat layer
which has excellent physical properties and high adhesion and
corrosion resistance.
[0037] At least one kind selected from the group consisting of
zirconium, titanium and hafnium contained in the chemical
conversion coating agent is a component constituting chemical
conversion coats and, by forming a chemical conversion coat
including at least one kind selected from the group consisting of
zirconium, titanium and hafnium on a material, the corrosion
resistance and abrasion resistance of the material can be improved
and, further, the adhesion to the coating film formed subsequently
can be enhanced.
[0038] A supply source of the zirconium is not particularly
limited, and examples thereof include alkaline metal
fluoro-zirconate such as K.sub.2ZrF.sub.6, fluoro-zirconate such as
(NH.sub.4).sub.2ZrF.sub.6, soluble fluoro-zirconate like
fluoro-zirconate acid such as H.sub.2ZrF.sub.6, zirconium fluoride,
zirconium oxide and the like.
[0039] A supply source of the titanium is not particularly limited,
and examples thereof include alkaline metal fluoro-titanate,
fluoro-titanate such as (NH.sub.4).sub.2TiF.sub.6, soluble
fluoro-titanate like fluoro-titanate acid such as H.sub.2TiF.sub.6,
titanium fluoride, titanium oxide and the like.
[0040] A supply source of the hafnium is not particularly limited,
and examples thereof include fluoro-hafnium acid such as
H.sub.2HfF.sub.6, hafnium fluoride and the like.
[0041] As a supply source of at least one kind selected from the
group consisting of zirconium, titanium and hafnium, a compound
having at least one kind selected from the group consisting of
ZrF.sub.6.sup.2-, TiF.sub.6.sup.2- and HfF.sub.6.sup.2- is
preferable because of high ability of forming a coat.
[0042] Preferably, the content of at least one kind selected from
the group consisting of zirconium, titanium and hafnium, which is
contained in the chemical conversion coating agent is within a
range from 20 ppm of a lower limit to 10000 ppm of an upper limit
in terms of metal. When the content is less than the above lower
limit, the performance of the chemical conversion coat to be
obtained is inadequate, and when the content exceeds the above
upper limit, it is economically disadvantageous because further
improvements of the performances cannot be expected. More
preferably, the lower limit is 50 ppm and the upper limit is 2000
ppm.
[0043] Fluorine contained in the chemical conversion coating agent
plays a role as an etchant of a material. A supply source of the
fluorine is not particularly limited, and examples thereof include
fluorides such as hydrofluoric acid, ammonium fluoride, fluoboric
acid, ammonium hydrogenfluoride, sodium fluoride, sodium
hydrogenfluoride and the like. In addition, an example of complex
fluoride includes hexafluorosilicate, and specific examples thereof
include hydrosilicofluoric acid, zinc hydrosilicofluoride,
manganese hydrosilicofluoride, magnesium hydrosilicofluoride,
nickel hydrosilicofluoride, iron hydrosilicofluoride, calcium
hydrosilicofluoride and the like.
[0044] The chemical conversion coating agent of the present
invention contains a water-soluble epoxy compound. It is considered
that when the water-soluble epoxy compound is blended in the
chemical conversion coating agent, an affinity for resin in a
coating composition is increased by an epoxy skeleton; therefore,
the adhesion to a coating films enhanced and the coating can
exhibit good stability.
[0045] The water-soluble epoxy compound is not particularly limited
as long as it has the solubility of a level to which it can
dissolve a required amount in a chemical conversion coating agent,
and a compound including an epoxy resin as a skeleton may be used.
The epoxy resin is not particularly limited, and examples thereof
include bisphenol A type epoxy resin, bisphenol F type epoxy resin,
hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F
type epoxy resin, bisphenol A propyleneoxide addition type epoxy
resin, bisphenol F propyleneoxide addition type epoxy resin,
novolac type epoxy resin and the like. Among them, bisphenol F type
epoxy resin is preferable and bisphenol F epichlorohydrin type
epoxy resin is more preferable.
[0046] Preferably, the water-soluble epoxy compound has an amino
group. Such a water-soluble epoxy compound having an amino group is
a cationic compound and adjusts a balance between hydrophilic and
hydrophobic properties; therefore, it has a property of becoming
insoluble and precipitating when a pH of an aqueous solution
increases. Therefore, the epoxy compound become prone to
precipitate on the surface of metal due to an increase of a pH in
an interface between metal and an aqueous solution. As a result of
analysis by X-ray photoelectron spectroscopy, it became apparent
that the above water-soluble epoxy compound having an amino group
is precipitated on a chemical conversion coat comprising at least
one kind selected from the group consisting of zirconium, titanium
and hafnium. It is estimated that the resulting chemical conversion
coat has such a structure, thereby improving the adhesion. The
amino group is not particularly limited, and examples thereof
include a --NH.sub.2 group, a monoalkylamino group, a dialkylamino
group, a monohydroxyamino group, a dihydroxyamino group, other
compounds including primary, secondary and tertiary amines, and the
like.
[0047] A reaction of introducing an amino group in an epoxy resin
constituting the above skeleton is not particularly limited, and
examples thereof include ordinary methods such as a method of
mixing an epoxy resin and an amine compound in a solvent, and the
like.
[0048] As an example of the water-soluble epoxy compound having an
amino group, commercially available products such as ADEKARESIN
EM-0436 series, ADEKARESIN EM-0436F series, ADEKARESIN EM-0718
series (each manufactured by Asahi Denka Co., Ltd.) can also be
used.
[0049] The water-soluble epoxy compound may have a phosphorus
element. The phosphorus element is preferably contained in the
water-soluble epoxy compound as a phosphate group. The phosphate
group may be partially alkylated. The phosphate group can be
introduced in an epoxy compound through a reaction of the epoxy
group and a phosphate compound.
[0050] The coat formed by the chemical conversion coating agent of
the present invention has curability. More specifically, by
containing a component causing a curing reaction after forming a
coat, it improves physical properties of a coating film and forms
an organic coat layer which is excellent in the adhesion and the
corrosion resistance. In the present invention, it is possible to
provide the obtained coat with curability by making the above
chemical conversion coating agent further contain a polyisocyanate
compound and/or a melamine resin or by making the above chemical
conversion coating agent contain a water-soluble epoxy compound
which has an isocyanate group and/or melamine group as the
water-soluble epoxy compound. In addition, the chemical conversion
coating agent of the present invention may use a water-soluble
epoxy compound which has an isocyanate group and/or a melamine
group as the above water-soluble epoxy compound is used and
simultaneously contain a polyisocyanate compound and/or melamine
resin.
[0051] In the case of using the chemical conversion coating agent
comprising the polyisocyanate compound and/or melamine resin, the
polyisocyanate compound and/or melamine resin precipitates
simultaneously when the water-soluble epoxy compound precipitates,
and the precipitated compound is subjected to heating and cured in
the following treatment step to obtain a cured film. The
polyisocyanate compound is a compound having two or more isocyanate
groups, and a blocked or half-blocked polyisocyanate compound which
is blocked with a blocking agent is preferably used in order to
stably blend the polyisocyanate compound in the water-borne
chemical conversion coating agent.
[0052] The blocked or half-blocked polyisocyanate compound is
obtained by adding a blocking agent to a polyisocyanate compound
and produces an isocyanate group through dissociation of the
blocking agent by heating. This isocyanate group causes a
crosslinking reaction with the water-soluble epoxy compound;
therefore, the adhesion to a coating film is further enhanced. The
polyisocyanate compound is not particularly limited, and examples
thereof include aliphatic diisocyanates such as hexamethylene
diisocyanate (including a trimer), tetramethylene diisocyanate and
trimethylhexamethylene diisocyanate, alicyclic polyisocyanates such
as isophorone diisocyanate and 4,4'-methylenebis(cyclohexyl
isocyanate), aromatic diisocyanates such as 4,4'-diphenylmethane
diisocyanate, trilene diisocyanate, xylylene diisocyanate, and the
like.
[0053] The blocking agent is not particularly limited, and examples
thereof can include monohydric alkyl (or aromatic) alcohols such as
n-butanol, n-hexyl alcohol, 2-ethylhexanol, lauryl alcohol, phenol
carbinol and methyl phenyl carbinol, cellosolves such as ethylene
glycol monohexyl ether and ethylene glycol mono-2-ethylhexyl ether,
phenols such as phenol, p-t-butylphenol and cresol, oxyms such as
dimethyl ketoxym, methyl ethyl ketoxym, methyl isobutyl ketoxym,
methyl amyl ketoxym and cyclohexanone ketoxym; lactams represented
by .epsilon.-caprolactam and .gamma.-butyrolactam, and the like.
Since blocking agents of oxyms and lactams dissociate at a low
temperature, they are more preferable from the viewpoint of
curability of resin.
[0054] The melamine resin is not particularly limited, and examples
thereof include alkoxymethylmelamine resin having alkoxy groups
such as methoxy group, ethoxy group, n-butoxy group and i-butoxy
group, and the like. The alkoxymethylmelamine resin is normally
obtained by etherizing methylolmelamine resin with monohydric
alcohol having 1 to 4 carbon atoms, the methylolmelamine resin
being obtained by adding aldehydes such as formaldehyde and
paraformaldehyde to melamine or by addition-condensing them. In the
present invention, the methyl ether group is suitable.
[0055] Specific examples of the melamine resin include CYMEL 303,
CYMEL 325, CYMEL 327, CYMEL 350, CYMEL 370, CYMEL 385 (each
manufactured by Mitsui Cytec Co., Ltd.), SUMIMAL M40S, SUMIMAL
M50S, SUMIMAL M100 (each manufactured by Sumitomo Chemical Co.,
Ltd.), and the like as a type having a methoxy group (methyl ether
type). In addition, specific examples of the melamine resin include
UVAN 20SE-60, UVAN 20SE-125, UVAN 20SE-128 (each manufactured by
Mitsui Chemicals Co., Ltd.), SUPER BECKAMINE G821, SUPER BECKAMINE
J820 (each manufactured by Dainippon Ink and Chemicals Co., Ltd.),
MYCOAT 506, MYCOAT 508 (each manufactured Mitsui Cytec Co., Ltd.),
and the like as a type having a butoxy group (butyl ether type).
Further, examples of a mixed ether type melamine include CYMEL 235,
CYMEL 238, CYMEL 254, CYMEL 266, CYMEL 267, CYMEL 285, CYMEL 1141
(each manufactured by Mitsui Cytec Co., Ltd.), NIKALAC MX-40,
NIKALAC MX-45 (each manufactured by Sanwa Chemical Co., Ltd.), and
the like.
[0056] The chemical conversion coating agent of the present
invention preferably contains the water-soluble epoxy compound and
the polyisocyanate compound and/or the melamine resin within a
range from 5 ppm of a lower limit to 5000 ppm of an upper limit in
a total amount as a concentration of solid matter. When the total
amount is less than 5 ppm, there is a possibility that a proper
performance after coating cannot be attained in the chemical
conversion coat to be obtained, and when it exceeds 5000 ppm, there
is a possibility that the chemical conversion coat is not formed
efficiently. More preferably, the lower limit is 30 ppm and the
upper limit is 2000 ppm.
[0057] In the chemical conversion coating agent of the present
invention, when the water-soluble epoxy compound containing the
isocyanate group and/or the melamine group is adopted, a cured film
can be formed because crosslinking is occurred by the isocyanate
group and/or a melamine group contained in the water-soluble epoxy
compound.
[0058] The isocyanate group may be introduced in the water-soluble
epoxy compound, for example, by reacting a half-blocked
diisocyanate compound blocked with a blocking agent with the
water-soluble epoxy compound.
[0059] The half-blocked diisocyanate compound may be obtained by
reacting a diisocyanate compound with a blocking agent in such a
rate that the isocyanate group is excessive. As the blocking agent
which can be used in the above reaction, the above-described
compounds may be used. Synthesis of the half-blocked diisocyanate
compound and a reaction of the half-blocked diisocyanate compound
and the water-soluble epoxy compound are not particularly limited
and may be performed by publicly known methods.
[0060] A method of introducing the melamine group in the
water-soluble epoxy compound is not particularly limited, and
examples thereof include a method wherein a melamine resin such as
CYMEL 385 is added to a bisphenol A type epoxy resin or a bisphenol
F type epoxy resin and the mixture is stirred at 80.degree. C. for
2 hours while being heated, and the like.
[0061] In the chemical conversion coating agent of the present
invention, since the ratio of a functional group between an epoxy
compound and an isocyanate group and/or a melamine group, between
which curing is occurred, is maintained constant, it is more
preferable to use the water-soluble epoxy compound containing the
isocyanate group and/or the melamine group rather that to use the
water-soluble epoxy compound and the polyisocyanate compound and/or
the melamine resin.
[0062] The chemical conversion coating agent of the present
invention preferably contains the water-soluble epoxy compound
containing the isocyanate group and/or the melamine group within a
range from 5 ppm of a lower limit to 5000 ppm of an upper limit as
a concentration of solid matter. When the content is less than 5
ppm, there is a possibility that a proper performance after coating
cannot be attained in the chemical conversion coat to be obtained,
and when it exceeds 5000 ppm, there is a possibility that the
chemical conversion coat is not formed efficiently. More
preferably, the lower limit is 30 ppm and the upper limit is 2000
ppm.
[0063] Preferably, the chemical conversion coating agent of the
present invention further contains a chemical conversion reaction
accelerator. The chemical conversion reaction accelerator has an
effect of suppressing unevenness of the surface of a chemical
conversion coat obtained using a metal surface treating agent
comprising a zirconium compound. An amount of a coat precipitated
is different depending on the difference of location between an
edge portion and a flat portion of a material; thereby, the
unevenness of the surface is generated. Therefore, when a metal
material having an edge portion is treated with a conventional
surface treating agent comprising a zirconium compound, since an
anodic dissolution reaction occurs selectively at an edge portion,
a cathodic reaction becomes prone to occur and, consequently, a
coat tends to precipitate around the edge portion and an anodic
dissolution reaction hardly occur in a flat portion and
precipitation of a coat is suppressed, and this results in
unevenness of the surface.
[0064] In the chemical conversion treatment of zinc phosphate,
since the resulting chemical conversion coat is a thick film type,
the unevenness of the surface does not turn into problems so much.
However, since the chemical conversion coat comprising a zirconium
compound is a thin film type, when a sufficient amount of a coat is
not attained at a flat portion to which the chemical conversion
treatment is hardly applied, this causes uneven coating and
problems may arise in appearance of a coating and corrosion
resistance.
[0065] The chemical conversion reaction accelerator in the present
invention has a property to act in such a manner that the chemical
conversion treatment may be applied without developing a difference
of a chemical conversion treatment reaction between the edge
portion and the flat portion described above by being blended in
the chemical conversion coating agent.
[0066] Although the chemical conversion reaction accelerator is at
least one kind selected from the group consisting of nitrite ions,
nitro group-containing compounds, hydroxylamine sulfate, persulfate
ions, sulfite ions, hyposulfite ions, peroxides, iron (III) ions,
citric acid iron compounds, bromate ions, perchlorinate ions,
chlorate ions, chlorite ions as well as ascorbic acid, citric acid,
tartaric acid, malonic acid, succinic acid and salts thereof, in
particular, a substance having an oxidizing action or an organic
acid is preferable for accelerating etching efficiently.
[0067] By blending these chemical conversion reaction accelerators
in the chemical conversion coating agent, unbalanced
coat-precipitation is adjusted and good chemical conversion coat
having no unevenness in an edge portion and a flat portion of a
material can be attained.
[0068] A supply source of the nitrite ion is not particularly
limited, and examples thereof include sodium nitrite, potassium
nitrite, ammonium nitrite and the like. The nitro group-containing
compound is not particularly limited, and examples thereof include
nitrobenzenesulfonic acid, nitroguanidine and the like. A supply
source of the persulfate ion is not particularly limited, and
examples thereof include Na.sub.2S.sub.2O.sub.8,
K.sub.2S.sub.2O.sub.8 and the like. A supply source of the sulfite
ion is not particularly limited, and examples thereof include
sodium sulfite, potassium sulfite, ammonium sulfite and the like. A
supply source of the hyposulfite ion is not particularly limited,
and examples thereof include sodium hyposulfite, potassium
hyposulfite, ammonium hyposulfite and the like. The peroxides is
not particularly limited, and examples thereof include hydrogen
peroxide, sodium peroxide, potassium peroxide and the like.
[0069] A supply source of the iron (III) ion is not particularly
limited, and examples thereof include ferric nitrate, ferric
sulfate, ferric chloride and the like. The citric acid iron
compound is not particularly limited, and examples thereof include
citric acid iron ammonium, citric acid iron sodium, citric acid
iron potassium and the like. A supply source of the bromate ion is
not particularly limited, and examples thereof include sodium
bromate, potassium bromate, ammonium bromate and the like. A supply
source of the perchlorinate ion is not particularly limited, and
examples thereof include sodium perchlorinate, potassium
perchlorinate, ammonium perchlorinate and the like.
[0070] A supply source of the chlorate ion is not particularly
limited, and examples thereof include sodium chlorate, potassium
chlorate, ammonium chlorate and the like. A supply source of the
chlorite ion is not particularly limited, and examples thereof
include sodium chlorite, potassium chlorite, ammonium chlorite and
the like. The ascorbic acid and salt thereof are not particularly
limited, and examples thereof include ascorbic acid, sodium
ascorbate, potassium ascorbate, ammonium ascorbate and the like.
The citric acid and salt thereof are not particularly limited, and
examples thereof include citric acid, sodium citrate, potassium
citrate, ammonium citrate and the like. The tartaric acid and salt
thereof are not particularly limited, and examples thereof include
tartaric acid, ammonium tartrate, potassium tartrate, sodium
tartrate and the like. The malonic acid and salt thereof are not
particularly limited, and examples thereof include malonic acid,
ammonium malonate, potassium malonate, sodium malonate and the
like. The succinic acid and salt thereof are not particularly
limited, and examples thereof include succinic acid, sodium
succinate, potassium succinate, ammonium succinate and the
like.
[0071] The above-described chemical conversion reaction
accelerators may be used alone or in combination of two Or more
kinds of components as required.
[0072] A blending amount of the chemical conversion reaction
accelerator in the chemical conversion coating agent of the present
invention is preferably within a range from 1 ppm of a lower limit
to 5000 ppm of an upper limit. When it is less than 1 ppm, it is
not preferred because an adequate effect cannot be attained. When
it exceeds 5000 ppm, there is a possibility of inhibiting coat
formation. The above lower limit is more preferably 3 ppm and
further more preferably 5 ppm. The above upper limit is more
preferably 2000 ppm and further more preferably 1500 ppm.
[0073] Preferably, the chemical conversion coating agent of the
present invention further contains at least one kind selected from
the group consisting of: at least one kind of metal ions (A)
selected from the group consisting of zinc ions, magnesium ions,
calcium ions, aluminum ions, manganese ions and iron ions; copper
ions (B); and a silicon-containing compound (C). By containing
these components, the chemical conversion coating agent can further
enhance the adhesion to a coating film.
[0074] Preferably, the content of at least one kind of metal ions
(A) selected from the group consisting of zinc ions, magnesium
ions, calcium ions, aluminum ions, manganese ions and iron ions is
within a range from 1 ppm of a lower limit to 5000 ppm of an upper
limit. When the content is less than 1 ppm, it is not preferable
since the corrosion resistance of the chemical conversion coat to
be obtained is deteriorated. When the content exceeds 5000 ppm, it
is economically disadvantageous because further improvement of the
performances is not recognized, and there is a possibility that
adhesion after coating is deteriorated. More preferably, the above
lower limit is 20 ppm and the above upper limit is 2000 ppm.
[0075] Preferably, the content of the copper ion (B) is within a
range from 0.5 ppm of a lower limit to 100 ppm of an upper limit.
When the content is less than 0.5 ppm, it is not preferable since
the corrosion resistance of the chemical conversion coat to be
obtained is deteriorated. When the content exceeds 100 ppm, there
is a possibility that a negative effect is brought about in a zinc
material and an aluminum material. More preferably, the above lower
limit is 2 ppm and the above upper limit is 50 ppm. The copper ion
(B) has particularly a high effect of stabilizing the chemical
conversion coats by applying displacement plating to the surface of
a metal material and, with respect to this point, it is estimated
that the copper ion can attain a high degree of effectiveness in a
small amount in comparison with another components because it
stabilizes rust forming on the metal material.
[0076] A supply source of the respective components (A) and (B) is
not particularly limited and, for example, they can be blended in
the chemical conversion coating agent as nitrate, sulfate or
fluoride. Among them, nitrate is preferable because it does not
adversely affect chemical conversion reaction.
[0077] The silicon-containing compound (C) is not particularly
limited, and examples thereof include silica such as
water-dispersed silica, water-soluble silicate compounds such as
sodium silicate, potassium silicate and lithium silicate, esters of
silicic acid, alkyl silicates such as diethyl silicate, a silane
coupling agent, and the like. Among them, silica is preferable
since it has an action of enhancing a barrier-effect of a chemical
conversion coat and water-dispersed silica is more preferable since
it has high dispersibility in the chemical conversion coating
agent. The water-dispersed silica is not particularly limited, and
examples thereof include spherical silica, chain silica,
aluminum-modified silica and the like, which have less impurities
such as sodium. The spherical silica is not particularly limited,
and examples thereof include colloidal silica such as "SNOWTEX N",
"SNOWTEX 0", "SNOWTEX OXS", "SNOWTEX UP", "SNOWTEX XS", "SNOWTEX
AK", "SNOWTEX OUP", "SNOWTEX C" and "SNOWTEX OL" (each manufactured
by Nissan Chemical Industries Co., Ltd.) and fumed silica such as
"AEROSIL" (manufactured by Nippon Aerosil Co., Ltd.), and the like.
The chain silica is not particularly limited, and examples thereof
include silica sol such as "SNOWTEX PS-M", "SNOWTEX PS-MO",
"SNOWTEX PS--SO" (each manufactured by Nissan Chemical Industries
Co., Ltd.), and the like. Examples of the aluminum-modified silica
include commercially available silica sol such as "ADELITE AT-20A"
(manufactured by Asahi Denka Co., Ltd.), and the like.
[0078] Preferably, the content of the silicon-containing compound
(C) is within a range from 1 ppm of a lower limit to 5000 ppm of an
upper limit as a silicon component. When the content is less than 1
ppm, it is not preferable since the corrosion resistance of the
chemical conversion coat to be obtained is deteriorated. When the
content exceeds 5000 ppm, it is economically disadvantageous
because further improvement of the performances is not recognized,
and there is a possibility that adhesion after coating is
deteriorated. More preferably, the above lower limit is 5 ppm and
the above upper limit is 2000 ppm.
[0079] Additional examples of the silicon-containing compound (C)
include a silane coupling agent and hydrolysate thereof. Although
the silane coupling agent is not particularly limited, for example,
an amino group-containing silane coupling agent is suitably used.
By blending the chemical conversion coating agent with the amino
group-containing silane coupling agent, a curing reaction is
accelerated at an interface between a chemical conversion coat and
a coating film formed through electrodeposition coating or powder
coating, and adhesion between the coat and the coating film is
improved. The amino group-containing silane coupling agent is not
particularly limited as long as it has at least one amino group and
has a siloxane linkage in a molecule.
[0080] The amino group-containing silane coupling agent is not
particularly limited, and examples thereof include
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-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane,
N,N-bis[3-(trimethoxysilyl)propyl]ethylenediamine and the like.
[0081] The silane coupling agent may also be hydrolysate thereof.
The hydrolysate of the silane coupling agent can be produced by a
publicly known method, for example, a method of dissolving a silane
coupling agent in ion-exchanged water and making the solution
acidic with any acid.
[0082] The respective components (A), (B) and (C) may be used alone
or in combination of two or more kinds of components as required.
When two or more kinds of components are used simultaneously, the
contents of the respective components are preferably within the
above ranges, respectively, and the total amount of the respective
components is not particularly limited.
[0083] Examples of a particularly preferable combination include a
combination of at least one kind of metal ions (A) selected from
the group consisting of zinc ions, magnesium ions, calcium ions,
aluminum ions, manganese ions and iron ions and copper ions (B),
and a combination of a silicon-containing compound (C) and copper
ions (B).
[0084] In the chemical conversion coating agent of the present
invention, a pH is preferably adjusted within a range from 1.5 of a
lower limit to 6.5 of an upper limit. When the pH is less than 1.5,
the adhesion to a coating film is not adequately improved in some
cases since a water-soluble epoxy compound becomes hard to
precipitate. When it exceeds 6.5, a chemical conversion treatment
reaction does not proceed adequately in some cases. More
preferably, the above lower limit is 2.0 and the above upper limit
is 5.5. Still more preferably, the above lower limit is 2.5 and the
above upper limit is 5.0. The chemical conversion coating agent of
the present invention may contain ions of a complex fluoride,
nitrate, sulfate, and salt of fluoride as described above, an
alkaline component is preferably added to the coating agent in
order to control a pH within the above range. An alkaline component
which can be used for adjusting a pH is not particularly limited,
and examples thereof include sodium hydroxide, potassium hydroxide,
ammonia, amine compounds and the like.
[0085] Preferably, the chemical conversion coating agent of the
present invention does not substantially contain phosphate ions.
Not substantially containing means that phosphate ions are not
contained to such an extent that the phosphate ions act as a
component in the chemical conversion coating agent. When the above
chemical conversion coating agent does not substantially contain
phosphate ions, phosphorus causing a burden on the environment is
not substantially used and the formation of the sludge such as iron
phosphate and zinc phosphate, formed in using a treating agent of
zinc phosphate, can be suppressed. Further, a burden on the
environment due to phosphorus is eliminated; therefore, this
becomes a large advantage in point of workability in wastewater
treatment.
[0086] A method of treating a metal surface with the chemical
conversion coating agent of the present invention is not
particularly limited, and this method can be performed by bringing
the chemical conversion coating agent into contact with the metal
surface. The treatment method is not particularly limited, and
examples thereof include an immersion method, a spray coating
method, a roller coating method and the like.
[0087] In the treatment method, treatment is preferably conducted
by controlling a temperature of a treating solution within a range
from 20.degree. C. of a lower limit to 70.degree. C. of an upper
limit. The chemical conversion treatment reaction can be performed
efficiently by conducting the chemical conversion treatment
reaction in such a range of temperature. More preferably, the above
lower limit is 30.degree. C. and the above upper limit is
50.degree. C. Treatment time varies depending on a concentration of
the chemical conversion coating agent and a treatment temperature,
and is preferably 20 to 300 seconds.
[0088] In the treatment method, it is preferable to perform
degreasing before applying the chemical conversion treatment using
the chemical conversion coating agent and rinsing with water after
degreasing, and postrinsing after the chemical conversion
treatment.
[0089] The above degreasing is performed to remove an oil matter or
a stain adhered to the surface of the material, and immersion
treatment is conducted usually at 30 to 55.degree. C. for about
several minutes with a degreasing agent such as phosphate-free and
nitrogen-free cleaning liquid for degreasing. It is also possible
to perform pre-degreasing before degreasing as required.
[0090] The above rinsing with water after degreasing is performed
by spraying once or more with a large amount of water for rinsing
in order to rinse a degreasing agent after degreasing.
[0091] The above postrinsing after the chemical conversion
treatment is performed once or more in order to prevent the
chemical conversion treatment from adversely affecting to the
adhesion and the corrosion resistance after the subsequent various
coating applications. In this case, it is proper to perform the
final rinsing with pure water. In this postrinsing after the
chemical conversion treatment, either spray rinsing or immersion
rinsing may be used, and a combination of these rinsing may be
adopted.
[0092] In addition, since the chemical conversion treatment using
the chemical conversion coating agent of the present invention does
not need to conduct a surface conditioning, it is excellent in
workability.
[0093] In the chemical conversion treatment using the chemical
conversion coating agent of the present invention, a drying step
after the postrinsing after the chemical conversion treatment is
not necessarily required. Even though coating is performed with the
chemical conversion coats being wet without drying, the resulting
performance is not affected. When drying is performed, it is
preferable to dry with cool air or hot air. When hot air drying is
selected, air temperature is preferably 300.degree. C. or less to
prevent the degradation of an organic matter.
[0094] Examples of a metal material treated with the chemical
conversion coating agent of the present invention include an iron
material, an aluminum material, a zinc material and the like. Iron,
aluminum and zinc materials mean an iron material in which a
material comprises iron and/or its alloy, an aluminum material in
which a material comprises aluminum and/or its alloy and a zinc
material in which a material comprises zinc and/or its alloy,
respectively. The chemical conversion coating agent of the present
invention can also be used for chemical conversion treatment of a
substance to be coated comprising a plurality of metal materials
among the iron material, the aluminum material and the zinc
material.
[0095] The chemical conversion coating agent of the present
invention is preferable in point of being able to form good coating
films to iron materials to which it is hard to supply sufficient
adhesion to a coating film by usual chemical conversion coating
agents of zirconium and the like; therefore, it can also be applied
for treating a substance to be treated which contains an iron
material at least in part. Accordingly, the chemical conversion
coating agent of the present invention has an excellent property
particularly in application to iron materials. A surface-treated
metal having the chemical conversion coat formed by using the
chemical conversion coating agent of the present invention is also
one of the present invention.
[0096] The iron material is not particularly limited, and examples
thereof include a cold-rolled steel sheet, a hot-rolled steel sheet
and the like. The aluminum material is not particularly limited,
and examples thereof include 5000 series aluminum alloy, 6000
series aluminum alloy and the like. The zinc material is not
particularly limited, and examples thereof include steel sheets,
which are plated with zinc or a zinc-based alloy through
electroplating, hot dipping and vacuum evaporation coating, such as
a galvanized steel sheet, a steel sheet plated with a zinc-nickel
alloy, a steel sheet plated with a zinc-iron alloy, a steel sheet
plated with a zinc-chromium alloy, a steel sheet plated with a
zinc-aluminum alloy, a steel sheet plated with a zinc-titanium
alloy, a steel sheet plated with a zinc-magnesium alloy and a steel
sheet plated with a zinc-manganese alloy, and the like. By using
the above chemical conversion coating agent, chemical conversion
treatment with iron, aluminum and zinc materials can be conducted
simultaneously.
[0097] Preferably, a coat amount of the chemical conversion coat
obtained by the chemical conversion coating agent of the present
invention is within a range from 0.1 mg/m.sup.2 of a lower limit to
500 mg/m.sup.2 of an upper limit in sum of a total amount of metals
contained in the chemical conversion coating agent and carbon
contained in the water-soluble epoxy compound. When this coat
amount is less than 0.1 mg/m.sup.2, it is not preferable since a
uniform chemical conversion coat cannot be attained. When it
exceeds 500 mg/m.sup.2, it is economically disadvantageous. More
preferably, the above lower limit is 5 mg/m.sup.2 and the above
upper limit is 200 mg/m.sup.2.
[0098] Coating which can be applied to a metal material having the
chemical conversion coat formed by the chemical conversion coating
agent of the present invention is not particularly limited, and
conventionally publicly known coating such as cationic
electrocoating and powder coating can be conducted. Particularly,
good treatment can be applied to all metals such as iron, zinc and
aluminum; therefore, it can be suitably used as pretreatment of
cationic electrocoating of a substance to be treated, at least a
part of which comprises an iron material. The cationic
electrocoating is not particularly limited, and a publicly known
cationic electrodeposition coating composition comprising aminated
epoxy resin, aminated acrylic resin, sulfonated epoxy resin and the
like can be applied.
[0099] The chemical conversion coating agent of the present
invention is a chemical conversion coating agent containing at
least one kind selected from the group consisting of zirconium,
titanium and hafnium as a component constituting a coat. Since the
chemical conversion coat formed by the chemical conversion coating
agent of the present invention has good adhesion to a coating film,
it can be adopted as pretreatment of a metal surface for improving
the adhesion of metal to a coating film. In addition, the chemical
conversion coating agent of the present invention can form a good
chemical conversion coat to iron materials to which sufficient
adhesion cannot be supplied by conventional chemical conversion
coating agents containing zirconium and the like, and by only
treating once a substance to be coated comprising various metal
materials such as iron, zinc, aluminum and like, surface treatment
for all metals can be performed.
[0100] The chemical conversion coating agent of the present
invention does not need to use heavy metals, which has a large
burden on the environment, such as chromium, and is also excellent
in point of workability and cost since a good chemical conversion
coat is formed without conditioning the surface in chemical
conversion treatment using the chemical conversion coating agent of
the present invention. Further, the chemical conversion coating
agent of the present invention can be suitably applied to a
substance to be treated, which contains an iron material at least
in part, since the chemical conversion coating agent can provide an
iron material with sufficient adhesion to a coating film.
EXAMPLES
[0101] Hereinafter, the present invention will be described in more
detail by way of examples, but the present invention is not limited
to these examples. Herein, a term "part" means "part by mass" and
"%" means "% by mass" in the examples, unless otherwise
specified.
Production Example 1
Method of Producing an Amino Group-Containing Water-Soluble Epoxy
Compound A
[0102] To 190 parts by mass of bisphenol F epichlorohydrin type
epoxy compound having an epoxy equivalent of 190 was added 30 parts
of diethanolamine and 110 parts of cellosolve acetate, and the
mixture was reacted at 100.degree. C. for 2 hours to obtain an
amino group-containing water-soluble epoxy compound A of
non-volatile content of 70%.
Production Example 2
Method of Producing an Amino Group-Containing Water-Soluble Epoxy
Compound B Having a Phosphorus Element
[0103] In 190 parts by mass of bisphenol F epichlorohydrin type
epoxy compound having an epoxy equivalent of 190 was blended 38
parts of monoethyl phosphate, and the mixture was stirred at
130.degree. C. for 3 hours to obtain an epoxy resin having a
phosphorus element. Further, 30 parts of diethanolamine and 110
parts of cellosolve acetate were added to the resulting epoxy resin
and the mixture was reacted at 100.degree. C. for 2 hours to obtain
an amino group-containing water-soluble epoxy compound B, having a
phosphorus element, of non-volatile content of 70%.
Production Example 3
Method of Producing an Amino Group-Containing Water-Soluble Epoxy
Compound C Having an Isocyanate Group
[0104] 100 parts of 2,4-toluenediisocyanate precopolymer of
trimethylolpropane of NCO of 13.3% and non-volatile content of 75%,
44 parts of nonylphenol, 5 parts of dimethylbenzylamine and 65
parts of cellosolve acetate were mixed, and the mixture was stirred
and reacted at 80.degree. C. for 3 hours in an atmosphere of
nitrogen to obtain a partially blocked polyisocyanate of
non-volatile content of 70% and NCO of 20%.
[0105] The amino group-containing water-soluble epoxy compound A
(70 parts) prepared in Production Example 1 and 30 parts of the
above partially blocked polyisocyanate were mixed, the mixture was
stirred and reacted at 80.degree. C. for 4 hours, and then it was
verified by an infrared spectroscopy that absorption of a NCO group
disappeared completely. Then, 3 parts of acetic acid was added to
the mixture and further the mixture was diluted with ion-exchanged
water to obtain an amino group-containing water-soluble epoxy
compound C having an isocyanate group, in which non-volatile
content was 25% and a pH was 4.1.
Production Example 4
Method of Producing an Amino Group-Containing Water-Soluble Epoxy
Compound D Having a Phosphorus Element and an Isocyanate Group
[0106] An amino group-containing water-soluble epoxy compound D
having a phosphorus element and an isocyanate group was obtained by
following the same procedure as that of Production Example 3 except
that the amino group-containing water-soluble epoxy compound B
having a phosphorus element prepared in Production Example 2 was
used in place of the amino group-containing water-soluble epoxy
compound A prepared in Production Example 1.
Production Example 5
Method of Producing an Amino Group-Containing Water-Soluble Epoxy
Compound E Having a Phosphorus Element and an Isocyanate Group
[0107] An amino group-containing water-soluble epoxy compound E
having a phosphorus element and an isocyanate group was obtained by
following the same procedure as that of Production Example 4 except
that a bisphenol A epichlorohydrin type epoxy compound having an
epoxy equivalent of 500 was used in place of a bisphenol F
epichlorohydrin type epoxy resin having an epoxy equivalent of 190
and further 65 parts of N-methylethanolamine and 245 parts of
cellosolve acetate were used in place of 30 parts of diethanolamine
and 110 parts of cellosolve acetate in amine-addition.
Production Example 6
Method of Producing an Amino Group-Containing Water-Soluble Epoxy
Compound G Having an Isocyanate Group
[0108] An amino group-containing water-soluble epoxy compound F was
obtained by following the same procedure as that of Production
Example 2 except that a bisphenol A epichlorohydrin type epoxy
compound having an epoxy equivalent of 190 was used in place of a
bisphenol F epichlorohydrin type epoxy resin having an epoxy
equivalent of 190. To another reactor was charged 174 parts of
2,4-toluenediisocyanate, 96 parts of phenol, 5 parts of
dimethylbenzylamine and 118 parts of ethyl acetate, and the mixture
was stirred and reacted at 80.degree. C. for 3 hours in an
atmosphere of nitrogen to obtain a partially blocked isocyanate of
non-volatile content of 70% and NCO of 10.6%. This partially
blocked isocyanate (30 parts) and 70 parts of the amino
group-containing water-soluble epoxy compound F were reacted at
80.degree. C. for 4 hours while being stirred. After it was
verified by an infrared spectroscopy that absorption of a NCO group
disappeared completely, 3 parts of acetic acid was added to the
mixture and the mixture was diluted with ion-exchanged water to
obtain an amino group-containing water-soluble epoxy compound G
having an isocyanate group, in which non-volatile content was 25%
and a pH was 4.1.
Examples 1 to 16, Comparative Examples 5 to 15
[0109] A commercially available cold-rolled steel sheet (SPCC-SD,
manufactured by Nippon Testpanel Co., Ltd., 70 mm.times.150
mm.times.0.8 mm), a galvanized steel sheet (GA steel sheet,
manufactured by Nippon Testpanel Co., Ltd., 70 mm.times.150
mm.times.0.8 mm), 5000 series aluminum (manufactured by Nippon
Testpanel Co., Ltd., 70 mm.times.150 mm.times.0.8 mm) or 6000
series aluminum (manufactured by Nippon Testpanel Co., Ltd., 70
mm.times.150 mm.times.0.8 mm) was used as a material and
pretreatment of coating was applied to these material in the
following conditions.
[0110] Pretreatment of Coating
[0111] Degreasing treatment: The metal materials were immersed at
40.degree. C. for 2 minutes with 2% by mass "SURF CLEANER EC92"
(degreasing agent manufactured by Nippon Paint Co., Ltd.).
[0112] Rinsing after degreasing: The metal materials were rinsed
for 30 seconds with a spray of running water.
[0113] Chemical conversion treatment: Chemical conversion coating
agents having compositions shown in Tables 1 and 2 were prepared
and chemical conversion treatment was conducted by immersing the
metal materials in the chemical conversion coating agents under the
conditions described in Tables 1 and 2. Herein, nitric acid and
sodium hydroxide were used for adjusting a pH.
[0114] Postrinsing after the chemical conversion treatment: The
metal materials were rinsed for 30 seconds with a spray of running
water. In addition, they were rinsed for 30 seconds with a spray of
ion-exchanged water. Electrocoating was applied to the metal
materials rinsed with water as is wet without drying it. But, the
chemical conversion coats obtained in Examples 14 and 16 and
Comparative Example 14 were dried with cool air and then
electrocoating was applied to them.
[0115] (2) Coating
[0116] After 1 m.sup.2 of the surface of the metal materials were
treated per 1 liter of the chemical conversion coating agent,
electrocoating was applied to the surface in such a manner that a
dried film thickness was 20 .mu.m using "POWERNIX 110" (a cationic
electrodeposition coating composition manufactured by Nippon Paint
Co., Ltd.) and, after rinsing with water, the metal materials were
heated and baked at 170.degree. C. for 20 minutes and test sheets
were prepared.
Comparative Examples 1 to 4
[0117] Test sheets were obtained by following the same procedure as
that of Example 1 except that chemical conversion treatment was
conducted by conditioning the surface at a room temperature for 30
seconds using "SURF FINE 5N-8M" (manufactured by Nippon Paint Co.,
Ltd.) after rinsing after degreasing and by immersing the test
sheets at 35.degree. C. for 2 minutes using "SURF DYNE SD-6350" (a
zinc phosphate-base chemical conversion coating agent manufactured
by Nippon Paint Co., Ltd.). The pHs of the chemical conversion
coating agents and treatment conditions are as shown in Table
2.
Examples 17 to 20
[0118] Using DURANATE E402 (produced by Asahi Kasei Co., Ltd.) as a
polyisocyanate compound and CYMEL 385 (produced by Mitsui Cytec
Co., Ltd.) as a melamine resin, the chemical conversion coating
agents having compositions shown in Table 3 were prepared and test
plates were prepared in the same manner as Example 1.
TABLE-US-00001 TABLE 1 Chemical Treat- conversion ment Temper-
Epoxy Si reaction time ature No Zr/Ti.sup.1) compound Metal ions
compound accelerator pH (sec) (.degree. C.) Example 1 Zr(100 ppm)
D(300 ppm) -- -- -- 4 60 40 2 Zr(100 ppm) E(300 ppm) Zn(500 ppm) --
-- 4 60 40 3 Zr/Ti(250/100) D(4000 ppm) Mg(300 ppm) + Ca(100 ppm)
-- -- 3.5 120 40 4 Zr(8000 ppm) C(1000 ppm) Mg(800 ppm) SiO.sub.2(3
ppm) -- 2.5 90 25 5 Zr(30 ppm) D(100 ppm) Zn(2 ppm) + Mg(2 ppm) +
A(50 ppm) -- 6 90 60 Al(2 ppm) 6 Zr(100 ppm) E(300 ppm) Cu(5 ppm)
-- -- 4 60 40 7 Zr(100 ppm) E(100 ppm) Zn(300 ppm) + Mn(30 ppm)
B(100 ppm) -- 3 90 40 8 Zr(250 ppm) D(500 ppm) Zn(500 ppm) C(4500
ppm) -- 4 60 40 9 Zr(500 ppm) C(300 ppm) Mg(500 ppm) D(100 ppm) --
4 60 40 10 Zr(250 ppm) D(300 ppm) Fe(100 ppm) + Zn(200 ppm)
SiO.sub.2(50 ppm) -- 4.5 1000 35 11 Zr(100 ppm) E(200 ppm) Cu(5
ppm) SiO.sub.2(100 ppm) -- 4 120 40 12 Ti(1000 ppm) C(500 ppm)
Zn(100 ppm) A(100 ppm) -- 4 60 35 13 Zr(3000 ppm) E(300 ppm) Zn(500
ppm) SiO.sub.2(200 ppm) -- 3.5 60 40 14 Zr(250 ppm) G(300 ppm)
Zn(1000 ppm) + Mg(500 ppm) SiO.sub.2(300 ppm) Nitrobenzene- 4 60 40
sulfonic acid (500 ppm) 15 Zr(100 ppm) G(300 ppm) -- -- Hydrogen
2.5 10 60 peroxide (2 ppm) 16 Zr(500 ppm) G(100 ppm) Zn(1000 ppm) +
Mg(500 ppm) A(30 ppm) Citric acid 4 10 40 (1000 ppm) Note 1:
H.sub.2ZrF.sub.6 was used as a source of Zr, and H.sub.2TiF.sub.6
was used as a source Ti. Note 2: The concentrations of metal ions
of Zr, Ti and the like are concentrations as metal components. Note
3: The concentration of an epoxy compound is represented as a
concentration of solid matter. Epoxy compound H; DENACAST EM-101
(manufactured by Nagase Co., Ltd., water-dispersed epoxy resin
formed by emulsifying bisphenol epichlorohydrin type epoxy resin)
Note 4: The concentrations of SiO.sub.2 and sodium silicate are
represented as a concentration of Si component. Si compound A;
KBP-90 (manufactured by Shin-Etsu Chemical Co., Ltd.) Si compound
B; .gamma.-aminopropyltriethoxysilane (manufactured by Shin-Etsu
Chemical Co., Ltd.) Si compound C; This is produced by adding
acetic acid to Si compound B, adjusting a pH of the mixture to 4
and then hydrolyzing the mixture at a room temperature for three
days. Si compound D; .gamma.-glycidoxypropyltriethoxysilane
(manufactured by Shin-Etsu Chemical Co., Ltd.) Note 5: Treated
materials are as follows: SPC; cold-rolled steel sheet; SPCC-SD
(manufactured by Nippon Testpanel Co., Ltd.) GA; galvanized steel
sheet (manufactured by Nippon Testpanel Co., Ltd.) 5000Al; 5000
series aluminum (manufactured by Nippon Testpanel Co., Ltd.)
6000Al; 6000 series aluminum (manufactured by Nippon Testpanel Co.,
Ltd.) Note 6: As the respective metals, nitrates were used.
TABLE-US-00002 TABLE 2 Chemical Treat- conversion ment Temper-
Epoxy Si reaction time ature No Zr/Ti.sup.1) compound Metal ions
compound accelerator pH (sec) (.degree. C.) Comparative 1 Zinc
phosphate -- -- -- -- -- 120 35 Example 2 Zinc phosphate -- -- --
-- -- 120 -- 3 Zinc phosphate -- -- -- -- -- 120 -- 4 Zinc
phosphate -- -- -- -- -- 120 -- 5 Zr(500 ppm) A(500 ppm) Zn(500
ppm) SiO.sub.2(500 ppm) -- 4 60 40 6 Zr(250 ppm) B(25 ppm) Zn(500
ppm) + Mg(500 ppm) -- -- 4 60 40 7 Ti(250 ppm) B(500 ppm) Cu(80
ppm) -- -- 4 10 35 8 Zr(500 ppm) A(500 ppm) -- Sodium silicate -- 4
60 40 (0.5 ppm) 9 Zr(100 ppm) H(300 ppm) -- -- -- 4 60 40 10
Zr(15000 ppm) H(20000 ppm) Fe(15000 ppm) SiO.sub.2(12000 ppm) -- 4
60 40 11 Zr(100 ppm) H(100 ppm) Cu(200 ppm) -- -- 4 90 40 12 Zr(10
ppm) H(500 ppm) Mn(0.5 ppm) Sodium silicate -- 4 3 18 (0.5 ppm) 13
Zr(250 ppm) -- -- -- Citric 4 60 40 acid iron ammonium (0.5 ppm) 14
Zr(200 ppm) -- Co(100 ppm) -- Sodium 4 60 75 bromate (6000 ppm) 15
Ti(10 ppm) -- Zn(0.5 ppm) + Al(0.5 ppm) + SiO.sub.2(0.5 ppm) Sodium
4 60 40 Cu(0.1 ppm) nitrite (10000 ppm)
TABLE-US-00003 TABLE 3 Treatment Epoxy Polyisocyanate Melamine time
Temperature No Zr/Ti compound compound resin pH (sec) (.degree. C.)
Example 17 Zr(100 ppm) H(250 ppm) 50 ppm 0 ppm 3.5 60 40 Example 18
Zr(200 ppm) B(250 ppm) 25 ppm 25 ppm 4.0 60 35 Example 19 Zr(100
ppm) H(300 ppm) 0 ppm 100 ppm 4.5 60 40 Example 20 Zr(150 ppm)
A(300 ppm) 3 ppm 3 ppm 3.7 60 40
[0119] Evaluation Test
[0120] <Coat Amount>
[0121] A coat amount was represented by the sum of a total amount
of metals contained in the chemical conversion coating agent and
carbon contained in the water-soluble epoxy compound, in the coat
obtained. The total amount of metals was measured by using
"XRF-1700" (X-ray fluorescence spectrometer manufactured by
Shimadzu Co., Ltd.) and the amount of carbon contained in the epoxy
compound was measured by using "RC 412" (a moisture content
analyzer manufactured by LECO Co., Ltd. USA).
[0122] <Appearance of Bath>
[0123] After 1 m.sup.2 of the surface of the metal material was
treated per 1 liter of the chemical conversion coating agent, haze
in the chemical conversion coating agent was observed visually.
Results of evaluation are shown in Table 4.
[0124] .smallcircle.: There is not haze
[0125] x: There is haze
[0126] <Secondary Adhesion Test (SDT)>
[0127] Two parallel lines, which have depth reaching the material,
were cut in a longitudinal direction on the obtained test sheet and
then the test sheet was immersed at 50.degree. C. for 480 hours in
5% aqueous solution of NaCl. After immersion, a cut portion was
peeled off with an adhesive tape and peeling of a coating was
observed.
[0128] .quadrature.: No peeled
[0129] .smallcircle.: Slightly peeled
[0130] x: Peeled 3 mm or more in width
[0131] Results of observations are shown in Table 4.
[0132] <Combined Cycle Corrosion Test (CCT)>
[0133] After the test sheet, which was obtained by applying
electrocoating in Examples and Comparative Examples, was cut with a
cutter, a cycle test was repeated by 60 times. This cycle comprises
a wet step 1 (2 hours, 40.degree. C., humidity 95%), salt spraying
(2 hours, 5% aqueous solution of NaCl, 35.degree. C.), a drying
step 1 (2 hours, 60.degree. C.), a wet step 2 (6 hours, 50.degree.
C., humidity 95%), a drying step 2 (2 hours, 60.degree. C.), a wet
step 3 (6 hours, 50.degree. C., humidity 95%). After cycle test, a
maximum width of blister on both sides of a cut portion was
measured. Evaluation criteria are as follows.
[0134] .quadrature.: 0 to 3.5 mm or less
[0135] .smallcircle.: 3.6 mm to less than 7 mm
[0136] x: 7 mm or more
Results of evaluations are shown in Table 4.
TABLE-US-00004 TABLE 4 Combined Appear- Coat cycle ance of amount
corrosion No bath Materials (mg/m2) SDT test(CCT) Ex. 1
.largecircle. SPC 28 .circleincircle. .circleincircle. Ex. 2
.largecircle. SPC 43 .circleincircle. .circleincircle. Ex. 3
.largecircle. GA 57 .circleincircle. .circleincircle. Ex. 4
.largecircle. GA 83 .circleincircle. .circleincircle. Ex. 5
.largecircle. 5000Al 5 .circleincircle. .circleincircle. Ex. 6
.largecircle. SPC 31 .circleincircle. .circleincircle. Ex. 7
.largecircle. SPC 68 .largecircle. .largecircle. Ex. 8
.largecircle. SPC 47 .circleincircle. .circleincircle. Ex. 9
.largecircle. SPC 69 .circleincircle. .circleincircle. Ex. 10
.largecircle. GA 366 .circleincircle. .circleincircle. Ex. 11
.largecircle. SPC 53 .circleincircle. .circleincircle. Ex. 12
.largecircle. 5000Al 73 .circleincircle. .circleincircle. Ex. 13
.largecircle. SPC 112 .circleincircle. .circleincircle. Ex. 14
.largecircle. SPC 155 .circleincircle. -- Ex. 15 .largecircle. GA
13 .circleincircle. -- Ex. 16 .largecircle. 5000Al 57
.circleincircle. -- Ex. 17 .largecircle. SPC 45 .circleincircle.
.circleincircle. Ex. 18 .largecircle. GA 61 .circleincircle.
.circleincircle. Ex. 19 .largecircle. 5000Al 47 .circleincircle.
.circleincircle. Ex. 20 .largecircle. GA 53 .circleincircle.
.circleincircle. Compar. Ex. 1 X SPC 2400 .circleincircle.
.largecircle. Compar. Ex. 2 X GA 3200 .circleincircle.
.circleincircle. Compar. Ex. 3 X 5000Al 1800 .circleincircle.
.circleincircle. Compar. Ex. 4 X 6000Al 1900 .circleincircle.
.circleincircle. Compar. Ex. 5 .largecircle. SPC 72 X X Compar. Ex.
6 .largecircle. SPC 68 X X Compar. Ex. 7 .largecircle. GA 52
.largecircle. X Compar. Ex. 8 .largecircle. 6000Al 60 .largecircle.
X Compar. Ex. 9 -- SPC 35 X X Compar. Ex. 10 X SPC 553 X X Compar.
Ex. 11 .largecircle. 5000Al 57 X X Compar. Ex. 12 .largecircle. SPC
0.05 X X Compar. Ex. 13 X SPC 25 X -- Compar. Ex. 14 .largecircle.
SPC 1 X -- Compar. Ex. 15 .largecircle. SPC 2.5 X --
[0137] Table 4 shows that there was not the formation of sludge in
the chemical conversion coating agent of the present invention and
the chemical conversion coat obtained by the chemical conversion
coating agent of the present invention has the good adhesion to a
coating film even in an iron material. On the other hand, the
chemical conversion coat obtained by the chemical conversion
coating agent prepared in Comparative Examples could not yield good
results in every items.
* * * * *