U.S. patent application number 14/000123 was filed with the patent office on 2013-12-05 for surface treatment method for metal member and metal member obtained by the same.
This patent application is currently assigned to AISIN KEIKINZOKU CO., LTD.. The applicant listed for this patent is Jin Shinmura, Izuru Sugiura, Arata Yoshida. Invention is credited to Jin Shinmura, Izuru Sugiura, Arata Yoshida.
Application Number | 20130319868 14/000123 |
Document ID | / |
Family ID | 46672651 |
Filed Date | 2013-12-05 |
United States Patent
Application |
20130319868 |
Kind Code |
A1 |
Yoshida; Arata ; et
al. |
December 5, 2013 |
SURFACE TREATMENT METHOD FOR METAL MEMBER AND METAL MEMBER OBTAINED
BY THE SAME
Abstract
A surface treatment method improves the surface properties of a
metal member while maintaining the metal surface texture, and a
metal member is obtained by the surface treatment method. The
surface-treated metal member is obtained by bringing a solution of
a fluorine-based polymer into contact with a surface of an anodic
oxidation coating that is formed on a surface of a metal and has
not been subjected to a sealing treatment, and subjecting the
anodic oxidation coating to a steam sealing treatment, the
surface-treated metal member comprising a fluorine-based polymer
layer having a thickness of 100 nm or less, and a composite sealed
layer that is formed continuously under the fluorine-based polymer
layer, the composite sealed layer having a configuration in which
the fluorine-based polymer is present inside pores formed in the
anodic oxidation coating.
Inventors: |
Yoshida; Arata; (Toyama,
JP) ; Shinmura; Jin; (Toyama, JP) ; Sugiura;
Izuru; (Kariya, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yoshida; Arata
Shinmura; Jin
Sugiura; Izuru |
Toyama
Toyama
Kariya |
|
JP
JP
JP |
|
|
Assignee: |
AISIN KEIKINZOKU CO., LTD.
Imizu-shi, Toyama
JP
|
Family ID: |
46672651 |
Appl. No.: |
14/000123 |
Filed: |
February 16, 2012 |
PCT Filed: |
February 16, 2012 |
PCT NO: |
PCT/JP2012/053635 |
371 Date: |
August 16, 2013 |
Current U.S.
Class: |
205/50 ;
205/199 |
Current CPC
Class: |
C25D 11/24 20130101;
C25D 11/246 20130101; C25D 11/30 20130101; C25D 11/22 20130101;
C25D 11/26 20130101; C25D 11/02 20130101 |
Class at
Publication: |
205/50 ;
205/199 |
International
Class: |
C25D 11/02 20060101
C25D011/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 18, 2011 |
JP |
2011-033126 |
Claims
1. A surface-treated metal member that is obtained by bringing a
solution of a fluorine-based polymer into contact with a surface of
an anodic oxidation coating that is formed on a surface of a metal
and has not been subjected to a sealing treatment, and subjecting
the anodic oxidation coating to a steam sealing treatment, the
surface-treated metal member comprising: a fluorine-based polymer
layer having a thickness of 100 nm or less; and a composite sealed
layer that is formed continuously under the fluorine-based polymer
layer, wherein the composite sealed layer has a configuration in
which the fluorine-based polymer is present inside pores formed in
the anodic oxidation coating.
2. The surface-treated metal member as defined in claim 1, wherein
the anodic oxidation coating that has not been subjected to a
sealing treatment has been subjected to electrolytic coloring.
3. A surface treatment method for a metal member comprising:
forming a porous anodic oxidation coating on a surface of a metal;
bringing a fluorine-based polymer solution into contact with the
anodic oxidation coating in a state in which the anodic oxidation
coating is unsealed or semi-sealed; and subjecting the anodic
oxidation coating to a steam sealing treatment.
4. The surface treatment method as defined in claim 3, further
comprising: subjecting the anodic oxidation coating to electrolytic
coloring after forming the porous anodic oxidation coating, but
before bringing the fluorine-based polymer solution into contact
with the anodic oxidation coating.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. National Stage Application of
International Application No. PCT/JP2012/053635 filed on Feb. 16,
2012, and published in Japanese as WO 2012/111739 on Aug. 23, 2012.
This application claims priority to Japanese Application No.
2011-033126 filed on Feb. 18, 2011. The disclosures of the above
applications are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a surface treatment method
for an anodizable metal member, and a metal member that is obtained
by the surface treatment method and exhibits improved surface
properties.
BACKGROUND ART
[0003] The surface of a metal member produced using aluminum, an
aluminum alloy, magnesium, a magnesium alloy, titanium, a titanium
alloy, or the like is generally provided with an anodic oxidation
coating in order to improve corrosion resistance, design, and the
like.
[0004] However, a metal member provided with only an anodic
oxidation coating may exhibit insufficient corrosion resistance
during long-term use.
[0005] A metal member provided with only an anodic oxidation
coating may also be easily contaminated.
[0006] When a coloring step (e.g., secondary electrolytic coloring)
is performed after anodizing, significant discoloration may occur
due to insufficient corrosion resistance of the anodic oxidation
coating.
[0007] In the fields of aluminum building materials and the like, a
clear coating is provided after anodizing via anionic
electrodeposition coating or the like in order to deal with the
above problems.
[0008] However, since a clear coating has a thickness as large as
10 to 20 .mu.m, the metal surface texture may be impaired.
[0009] Therefore, it is difficult to deal with the above problems
by providing a clear coating when producing an automotive
decorative member (e.g., decorative trim) for which the metal
surface texture is important.
[0010] A transparent fluororesin coating that can provide corrosion
resistance with a reduced thickness as compared with an acrylic
clear coating or a urethane clear coating has been proposed.
[0011] JP-A-2006-257552 that aims at dealing with a wax remover
discloses a technique that forms a polytetrafluoroethylene (PTFE)
coating layer on the surface of an alumite coating.
[0012] However, since JP-A-2006-257552 states that it is
appropriate that the thickness of the PTFE coating layer is 3
.mu.m, a film-like surface texture is necessarily observed.
Moreover, since JP-A-2006-257552 states that it is necessary to
apply a primer or enlarge the pores formed in the anodic oxidation
coating, the process is complex, and the treatment cost
increases.
[0013] JP-A-2000-126680 discloses immersing a metal material
provided with an anodic oxidation coating in a solution that
contains a hydrophilic amorphous fluororesin so that the amorphous
fluororesin enters the pores formed in the anodic oxidation
coating. However, it is necessary to perform a preliminary heat
treatment in order to improve the quality, and polymerize the
fluororesin layer on the anodic oxidation coating by heating at
200.degree. C. for 30 minutes.
[0014] Therefore, the coating layer disclosed in JP-A-2000-126680
has a large thickness, and a film-like surface texture is
necessarily observed. Moreover, cracks may occur in the anodic
oxidation coating when the anodic oxidation coating is heated at a
high temperature of 200.degree. C.
DISCLOSURE OF THE INVENTION
Technical Problem
[0015] An object of the invention is to provide a surface treatment
method that improves the surface properties of a metal member while
maintaining the metal surface texture, and a metal member that is
obtained by the surface treatment method.
Solution to Problem
[0016] According to one aspect of the invention, a surface-treated
metal member that is obtained by bringing a solution of a
fluorine-based polymer (hereinafter may be referred to as
"fluorine-based polymer solution") into contact with a surface of
an anodic oxidation coating that is formed on a surface of a metal
and has not been subjected to a sealing treatment, and subjecting
the anodic oxidation coating to a steam sealing treatment,
[0017] the surface-treated metal member comprising:
[0018] a fluorine-based polymer layer having a thickness of 100 nm
or less, and
[0019] a composite sealed layer that is formed continuously under
the fluorine-based polymer layer,
[0020] wherein the composite sealed layer has a configuration in
which the fluorine-based polymer is present inside pores formed in
the anodic oxidation coating.
[0021] An electrolytic coloring step may be performed after forming
the anodic oxidation coating as long as the fluorine-based polymer
solution is brought into contact with the anodic oxidation coating
that has not been subjected to a sealing treatment, and the anodic
oxidation coating is then subjected to the steam sealing
treatment.
[0022] According to another aspect of the invention, a surface
treatment method for a metal member comprising:
[0023] forming a porous anodic oxidation coating on a surface of a
metal, bringing a fluorine-based polymer solution into contact with
the anodic oxidation coating in a state in which the anodic
oxidation coating is unsealed or semi-sealed, and
[0024] subjecting the anodic oxidation coating to a steam sealing
treatment.
[0025] The surface treatment method may further include subjecting
the anodic oxidation coating to electrolytic coloring after forming
the anodic oxidation coating, but before bringing the
fluorine-based polymer solution into contact with the anodic
oxidation coating.
[0026] The surface-treated metal member according to one aspect of
the invention is characterized by including the composite sealed
layer that is formed by subjecting the anodic oxidation coating to
the steam sealing treatment in a state in which the fluorine-based
polymer is present inside the pores formed in the anodic oxidation
coating from the viewpoint of maintaining the metal surface
texture. It suffices that the fluorine-based polymer layer that is
formed continuously over the composite sealed layer have a small
thickness.
[0027] The thickness of the fluorine-based polymer layer is
adjusted to 100 nm or less, and preferably 10 nm or less, in order
to prevent a situation in which the surface of the anodic oxidation
coating has a film-like texture.
[0028] The aspects of the invention are applied to a metal member
on which a porous anodic oxidation coating can be formed. The
aspects of the invention are mainly applied to a metal member
formed of aluminum, magnesium, titanium, or an alloy thereof.
[0029] The type of the anodic oxidation coating is not particularly
limited as long as the anodic oxidation coating is porous. The
metal member is anodized using a known electrolytic solution such
as sulfuric acid or an organic acid.
[0030] The expression "has not been subjected to a sealing
treatment" used herein in connection with the anodic oxidation
coating means that the anodic oxidation coating has not been
subjected to the steam sealing treatment, and means that the anodic
oxidation coating may have been washed with water, washed with hot
water, or semi-sealed using hot water at 60 to 90.degree. C.
[0031] The anodic oxidation coating may have been washed with
water, subjected to electrolytic coloring, and washed with water or
hot water.
[0032] The term "electrolytic coloring" used herein refers to
subjecting the anodic oxidation coating that has not been subjected
to a sealing treatment to a DC electrolysis, AC electrolysis, or
the like in an aqueous solution that includes metal ions (e.g.,
nickel ions or tin ions) to deposit the metal ions inside the pores
formed in the anodic oxidation coating.
[0033] The term "steam sealing treatment" used herein refers to a
sealing treatment that utilizes normal-pressure steam or
pressurized steam.
[0034] The fluorine-based polymer used in connection with the
aspects of the invention is a fluorine-based polymer that has such
a molecular weight that the fluorine-based polymer can be dissolved
in a solvent to prepare a solution.
[0035] Examples of the fluorine-based polymer include
polytetrafluoroethylene, a polytetrafluoroethylene copolymer such
as an ethylene-tetrafluoroethylene copolymer, polyvinyl fluoride, a
copolymer thereof, polyvinylidene fluoride, a copolymer thereof,
polychlorotrifluoroethylene, a copolymer thereof, and the like.
[0036] It is also effective to use a perfluoroalkyl
group-containing fluorine-based polymer that is provided with water
repellency and oil repellency and exhibits improved stain-proof
properties.
[0037] Examples of the perfluoroalkyl group-containing
fluorine-based polymer include a polyperfluoroalkyl (meth)acrylate,
a poly(2-(perfluoroalkyl)ethyl (meth)acrylate), a
tetrafluoroethylene-perfluoroalkyl vinyl ether, a
poly(perfluoroalkyl vinyl ether), a poly(2-(perfluoro(alkyl)ethyl
vinyl ether), and the like.
[0038] The perfluoroalkyl group is preferably represented by
C.sub.nF.sub.2n+1 (wherein n is an integer from 1 to 6).
[0039] The solvent used in connection with the aspects of the
invention may be an organic solvent such as a ketone (e.g.,
acetone, MEK, or MIBK), ethyl acetate, butyl acetate, diethyl
ether, dioxane, ethanol, or isopropyl alcohol. It is preferable to
use a fluorine-based solvent that exhibits high affinity to the
fluorine-based polymer.
[0040] The fluorine-based solvent also has an advantage in that it
is unnecessary to use special ventilation/explosion-proof
equipment.
[0041] Examples of the fluorine-based solvent include a
perfluorocarbon, a hydrofluorocarbon, a hydrochlorofluorocarbon, a
hydrofluoroether, a perfluoropolyether, a hydrofluoropolyether, and
the like.
[0042] The fluorine-based polymer solution may be brought into
contact with the anodic oxidation coating using an arbitrary means
such as dipping, spraying, or brush coating.
ADVANTAGEOUS EFFECTS OF THE INVENTION
[0043] Since the surface-treated metal member according to one
aspect of the invention includes the composite sealed layer in
which the fluorine-based polymer is present inside the pores formed
in the anodic oxidation coating, the surface-treated metal member
exhibits excellent adhesion. Since the fluorine-based polymer layer
that is formed continuously over the composite sealed layer has a
thickness as small as 100 nm or less, the surface-treated metal
member does not show a film-like texture.
[0044] Therefore, the surface-treated metal member exhibits
excellent long-term corrosion resistance, is not easily
contaminated, and can be easily cleaned by wiping the
surface-treated metal member due to the water repellency and the
oil repellency of the fluorine-based polymer.
[0045] When the surface-treated metal member has been subjected to
electrolytic coloring, discoloration can be suppressed due to the
improved corrosion resistance of the anodic oxidation coating.
BRIEF DESCRIPTION OF DRAWINGS
[0046] FIG. 1 shows sample production conditions.
[0047] FIG. 2 shows evaluation results for samples.
[0048] FIG. 3 shows an SEM image.
[0049] FIG. 4 shows cross-sectional elemental analysis results.
[0050] FIG. 5 shows evaluation results for samples subjected to
secondary electrolytic coloring.
[0051] FIG. 6 shows photographs of samples subjected to secondary
electrolytic coloring after a salt spray test.
DESCRIPTION OF EMBODIMENTS
[0052] Metal member production examples according to several
embodiments of the invention are described in detail below. Note
that the invention is not limited to the following examples.
[0053] The surface of an extruded shape (T5 material) produced by
extrusion using a JIS A 6063 alloy was subjected to a pretreatment
(buffing and chemical polishing).
[0054] The extruded shape was anodized using a 15% sulfuric acid
electrolytic solution at a current density of 1 A/dm.sup.2 and a
bath temperature of 20.degree. C. to form an anodic oxidation
coating having a thickness of 10 .mu.m on the surface of the
extruded shape (metal).
[0055] In Example 1, the anodic oxidation coating was washed with
water. In Example 2, the anodic oxidation coating was subjected to
a semi-sealing treatment (washing) at 80.degree. C. for 10 minutes
using purified water. In Examples 1 and 2, the anodic oxidation
coating was then dipped in a fluorine-based polymer solution
prepared by dissolving a fluorine-based polymer in a fluorine-based
solvent ("OPC-800" manufactured by Noda Screen Co., Ltd.), and
removed from the solution.
[0056] In Example 3, the fluorine-based polymer solution was
sprayed onto the surface of the anodic oxidation coating.
[0057] The thickness of the fluorine-based polymer that adhered to
the surface of the anodic oxidation coating removed from the
fluorine-based polymer solution after dipping was estimated to be
about 10 nm.
[0058] In Examples 1 to 3, the anodic oxidation coating was then
subjected to a sealing treatment for 20 minutes using steam at
150.degree. C.
[0059] Note that the steam sealing treatment may be performed under
normal pressure. In this case, however, the sealing time may
relatively increase. Therefore, it is preferable to perform the
steam sealing treatment using pressurized steam at 130 to
180.degree. C. (for 10 to 30 minutes).
[0060] In Comparative Example 1, the anodic oxidation coating was
subjected to a boiling water sealing treatment at 100.degree. C.
for 20 minutes using purified water.
[0061] In Comparative Example 2, a fluororesin primer was applied
to the anodic oxidation coating subjected to a boiling water
sealing treatment in the same manner as in Comparative Example 1,
and the anodic oxidation coating was then dipped in the
fluorine-based polymer solution, and dried.
[0062] In Comparative Example 3, the anodic oxidation coating was
treated, and dipped in the fluorine-based polymer solution in the
same manner as in Example 2, but was then dried without subjecting
the anodic oxidation coating to the steam sealing treatment.
[0063] In Comparative Example 4, the anodic oxidation coating was
treated, and dipped in the fluorine-based polymer solution in the
same manner as in Example 2, but was then subjected to a boiling
water sealing treatment at 100.degree. C. for 20 minutes using
purified water.
[0064] The external appearance of the samples obtained in Examples
1 to 3 and Comparative Examples 1 to 4 was evaluated with the naked
eye. The samples were then subjected to a 200 hr salt spray test,
and the color difference due to the test was measured (chroma
meter: "CR-400" manufactured by KONICA MINOLTA INC.).
[0065] FIG. 1 shows the sample production conditions, and FIG. 2
shows the evaluation results.
[0066] Note that "DIP" in FIG. 1 refers to "dipping".
[0067] As shown in FIG. 2, the samples obtained in Examples 1 to 3
maintained their metal surface texture, and did not show a change
in surface quality due to the salt spray test.
[0068] In contrast, the sample obtained in Comparative Example 1
showed slight surface whitening, and the sample obtained in
Comparative Example 2 showed a trace of the primer, and had an
inferior texture.
[0069] The sample obtained in Comparative Example 3 was not
subjected to the steam sealing treatment after dipping the anodic
oxidation coating in the fluorine-based polymer solution. As a
result, the sample obtained in Comparative Example 3 showed
whitening (discoloration) when subjected to the salt spray
test.
[0070] The sample obtained in Comparative Example 4 was subjected
to the boiling water sealing treatment after dipping the anodic
oxidation coating in the fluorine-based polymer solution. As a
result, the sample obtained in Comparative Example 4 showed slight
surface whitening.
[0071] It was thus confirmed that it is insufficient to merely dip
the anodic oxidation coating in the fluorine-based polymer
solution, or spray the fluorine-based polymer solution onto the
anodic oxidation coating, and it is effective to perform the steam
sealing treatment after dipping the anodic oxidation coating in the
fluorine-based polymer solution, or spraying the fluorine-based
polymer solution onto the anodic oxidation coating.
[0072] The cross section of the sample obtained in Example 2 was
observed using a scanning electron microscope (SEM), and the
elements were semi-quantitatively analyzed.
[0073] The results are shown in FIGS. 3 and 4.
[0074] A scanning electron microscope "JSM-7000FZ" (manufactured by
JEOL Ltd.) was used for cross-sectional observation, and an EDS
analyzer "EX-2300xBU" (manufactured by JEOL Ltd.) was used for
semi-quantitative elemental analysis.
[0075] FIG. 3 shows the resulting SEM photograph.
[0076] FIG. 4 shows the elemental analysis results for the surface,
the upper part of the cross section, and the lower part of the
cross section (see FIG. 3).
[0077] The thickness of the fluorine-based polymer layer formed on
the surface could not be measured since the thickness of the
fluorine-based polymer layer was very small. Since fluorine was
detected (deposited) in the upper part of the cross section of the
anodic oxidation coating, it was confirmed that a composite sealed
layer was formed in which fluorine was present inside the pores
formed in the anodic oxidation coating.
[0078] In order to check the effects of electrolytic coloring, a
sample of Example 4 was obtained in the same manner as in Example
1, and subjected to the salt spray test, except that the anodic
oxidation coating was washed with water, and subjected to secondary
electrolytic coloring (black) using a nickel-tin mixed bath.
[0079] In Comparative Example 5, the anodic oxidation coating was
subjected to secondary electrolytic coloring in the same manner as
in Example 4, and then subjected to the boiling water sealing
treatment in the same manner as in Comparative Example 1 without
bringing the fluorine-based polymer solution into contact with the
anodic oxidation coating.
[0080] FIG. 5 shows the measurement results for the color
difference due to the salt spray test.
[0081] FIG. 6 shows photographs of the samples obtained in Example
4 and Comparative Example 5 after the salt spray test.
[0082] It was thus confirmed that the anodic oxidation coating
subjected to secondary electrolytic coloring maintained its metal
surface texture, and exhibited improved corrosion resistance as a
result of forming the fluorine-based polymer layer on the anodic
oxidation coating, and subjecting the anodic oxidation coating to
the steam sealing treatment.
INDUSTRIAL APPLICABILITY
[0083] The surface treatment method according to the embodiments of
the invention is suitable for a metal member on which a porous
anodic oxidation coating can be formed, and may be applied to
various fields (e.g., automotive parts) that utilize such a metal
member.
* * * * *