The surface-treated metal sheet according to the first embodiment includes a
metal sheet and a coating film (hereinafter, occasionally referred to as a "resin
30 coating film") placed on at least one major surface of the metal sheet,
the coating film contains oxide particles, a binder resin, and electrically
5
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conductive particles,
the amount of electrically conductive particles contained is 5 to 30 mass%
relative to the coating film,
the oxide particles include non-doped oxide particles,
the non-doped oxide particles include at least one kind selected from the
group consisting of zinc oxide particles, tin oxide particles, magnesium oxide
particles, calcium oxide particles, and strontium oxide particles,
the amount of oxide particles contained is 1 to 10 mass% relative to the
coating film, and
10 the amount of the coating film attached to the major surface mentioned
above is 2 to 20 g/m2
.
[0024]
The surface-treated metal sheet according to the first embodiment is
excellent in both the adhesiveness to a coating treatment film after coating and
15 weldability by virtue of the configuration mentioned above. The reason is not
necessarily clear, but is presumed as follows.
[0025]
As described above, a molded material used for an automobile body
member as an outer sheet is generally subjected to coating. In this case, on the resin
20 coating film of the surface-treated metal sheet, chemical conversion treatment is
generally performed before coating, and a chemical conversion treatment covering
film is formed. A typical example of the chemical conversion treatment covering
film is an oxychloride covering film such as a phosphate covering film, and the
chemical conversion treatment liquid for forming the oxychloride covering film such
25 as a phosphate covering film exhibits acidity (e.g., a pH of 2 to 3).
[0026]
When the prescribed contained amount mentioned above of non-doped
oxide particles are put in the resin coating film of the surface-treated metal sheet, the
non-doped oxide particles are present in a state where some of them are exposed on
30 the surface of the resin coating film and others are dispersed in the interior of the
outer layer of the resin coating film (see FIG. 1A). Each of the zinc oxide particle,
5
PCT/JP2016/060488
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the tin oxide particle, the magnesium oxide particle, the calcium oxide particle, and
the strontium oxide particle has the property of being dissolved in an acidic solution
(e.g., a pH of2 to 3).
[0027]
Hence, when chemical conversiOn treatment with an acidic chemical
conversion treatment liquid is performed on the resin coating film containing nondoped
oxide particles, the non-doped oxide particles exposed on the surface of the
resin coating film are dissolved by the acidic chemical conversion treatment liquid.
Then, the pH of their vicinity increases, and components of the chemical conversion
10 treatment liquid (e.g., an oxychloride such as a phosphate) deposit and grow.
Thereby, a chemical conversion treatment covering film is formed. It is presumed
that at this time also the non-doped oxide particles existing in the interior of the outer
layer of the resin coating film are dissolved by the acidic chemical conversion
treatment liquid, and components of the chemical conversion treatment liquid enter
15 the interior of the outer layer of the resin coating film and deposit, and grow in a
wedge form so as to protrude from the interior to the surface of the outer layer of the
resin coating film (see FIG. lB). When a coating treatment film based on coating is
formed on the chemical conversion treatment covering film in this state (see FIG.
l C), the adhesiveness between the resin coating film and the coating treatment film
20 (in particular, the secondary adhesiveness after a warm salt water test) is further
enhanced by, in addition to the high adhesiveness by the chemical conversion
treatment covering film itself, the anchor effect by a crystal of the chemical
conversion treatment covering film that has grown in a wedge form (e.g., a crystal of
an oxychloride such as a phosphate).
25 [0028]
Here, the presence or absence of a crystal of the chemical converswn
treatment covering film (e.g., a crystal of an oxychloride such as a phosphate) can be
checked by surface observation with a scanning electron microscope (SEM) or from
diffraction peaks obtained by X -ray diffraction analysis.
30 [0029]
The resin coating film increases in electrical conductivity by setting the
PCT/JP2016/060488
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attached amount in the range mentioned above and putting in electrically conductive
particles in the range mentioned above, and is also excellent in weldability because
there is little hindrance to electrical conductivity caused by the non -doped oxide
particles.
5 [0030]
10
15
From the above, it is presumed that the surface-treated metal sheet
according to the first embodiment is excellent in both the adhesiveness to a coating
treatment film after coating and weldability by virtue of the configuration mentioned
above.
In the frrst embodiment, in FIG. 1, 10 represents the resin coating film, 12
represents the oxide particle, 14 represents the crystal of the chemical conversion
treatment covering film (e.g., a crystal of an oxychloride such as a phosphate), and
16 represents the coating treatment film.
[0031]
In the surface-treated metal sheet according to the frrst embodiment, anticorrosive
particles may be contained in the resin coating film. The anti-corrosive
particles, depending on their types, are dissolved by an acidic chemical conversion
treatment liquid. However, when non-doped oxide particles are put in the resin
coating film along with the anti-corrosive particles, the non-doped oxide particles are
20 actively dissolved by the acidic chemical conversion treatment liquid, and
accordingly the anti-corrosive particles are dissolved less easily. Thereby, corrosion
resistance is easily improved.
[0032]
In the surface-treated metal sheet according to the first embodiment, the
25 resin coating film may be formed on both surfaces (both major surfaces) of the metal
sheet, or may be formed only on one surface (one major surface) of the metal sheet,
in accordance with the use. The resin coating film may be formed on part of the
surface of the metal sheet, or the entire surface of the metal sheet may be covered.
The part of the metal sheet where the resin coating film is formed is excellent in the
30 adhesiveness to a coating treatment film and resistance weldability. The part is
excellent also in corrosion resistance and moldability.
PCT/JP2016/060488
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[0033]
The surface-treated metal sheet according to the first embodiment will now
be described in detail.
[0034]
5 [Metal sheet]
As the metal sheet, vanous metal sheets of steel (iron-based alloys),
aluminum and alloys of aluminum, and magnesium and alloys of magnesium are
gtven.
[0035]
10 Examples of the steel sheet include known plated steel sheets such as a zincbased
plated steel sheet and an aluminum-based plated steel sheet. The steel sheet
may be a plain steel sheet or a steel sheet containing an additive element such as
chromium. However, in the case of press molding, the steel sheet is preferably a
steel sheet in which the types and added amounts of additive elements and the metal
15 structure are appropriately controlled so that desired molding followability is
provided.
[0036]
Examples of the zinc-based plating layer of the zinc-based plated steel sheet
include a plating layer made of zinc, an alloy plating layer of zinc and at least one of
20 aluminum, cobalt, tin, nickel, iron, chromium, titanium, magnesium, and manganese,
and various zinc-based alloy plating layers further containing another metal element
or non-metal element (e.g., a quaternary alloy plating layer of zinc, aluminum,
magnesium, and silicon). However, in the zinc-based plating layer, the alloy
components other than zinc are not particularly limited.
25 These zinc-based plating layers may further contain, as a small amount of a
different metal element or impurity, cobalt, molybdenum, tungsten, nickel, titanium,
chromium, aluminum, manganese, iron, magnesium, lead, bismuth, antimony, tin,
copper, cadmium, arsenic, or the like, and may contain an inorganic substance such
as silica, alumina, or titania.
30 [0037]
Examples of the aluminum-based plating layer of the aluminum-based
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plated steel sheet include a plating layer made of aluminum, an alloy plating layer of
aluminum and at least one of silicon, zinc, and magnesium (e.g., an alloy plating
layer of aluminum and silicon, an alloy plating layer of aluminum and zinc, and a
tertiary alloy plating layer of aluminum, silicon, and magnesium), and the like.
5 [0038]
The zinc-based plated steel sheet and the aluminum-based plated steel sheet
may also be a multiple-layer plated steel sheet in combination with another type of
plating layer (e.g., an iron plating layer, an alloy plating layer of iron and phosphorus,
a nickel plating layer, a cobalt plating layer, etc.).
10 [0039]
The method for forming the plating layer of the plated steel sheet is not
particularly limited. For example, the formation of the plating layer may use
electroplating, electroless plating, hot dipping, vapor deposition plating, dispersion
plating, and the like. The plating layer may be formed by either the continuous
15 system or the batch system. After the formation of the plating layer, treatment such
as zero spangle treatment that is an external appearance uniformity treatment,
annealing treatment that is a modification treatment of the plating layer, or temper
rolling for adjusting the surface condition or the material quality may be performed.
[0040]
20 [Resin coating film]
The resin coating film is placed on at least one major surface (that is, at least
one surface) of the metal sheet described above. The resin coating film contains a
binder resin, electrically conductive particles, and non-doped oxide particles. The
resin coating film may contain anti-corrosive particles and other additives, as
25 necessary.
[0041]
(Non-doped oxide particles)
The non-doped oxide particles can improve the adhesiveness between the
resin coating film and the coating treatment film via the chemical conversion
30 treatment covering film, as described above. The non-doped oxide particles include
at least one kind selected from the group consisting of zinc oxide particles, tin oxide
PCT/JP2016/060488
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particles, magnesium oxide particles, calcium oxide particles, and strontium oxide
particles. Among these, at least one kind selected from the group consisting of
magnesium oxide particles, zinc oxide particles, tin oxide particles, and calcium
oxide particles are preferable as the oxide particles in terms of improving the
5 adhesiveness to a coating treatment film.
[0042]
The zmc oxide particles, after dissolved by the chemical conversiOn
treatment liquid, promote the growth of the crystal of the chemical conversiOn
treatment covering film (e.g., a crystal of an oxychloride such as a phosphate);
10 therefore, the adhesiveness between the resin coating film and the coating treatment
film can be further improved by the anchor effect of the crystal of the chemical
conversion treatment covering film.
The magnesium oxide particles, the calcium oxide particles, and the
strontium oxide particles (in particular, the magnesium oxide particles, the calcium
15 oxide particles, and the tin oxide particles), after dissolved by the chemical
conversion treatment liquid, are incorporated into the chemical conversion treatment
covering film. A chemical conversion treatment covering film containing Mg, Ca,
Sn, or Sr, which has corrosion resistance, is formed, and corrosion resistance can be
improved more.
20 [0043]
The average particle diameter of the non-doped oxide particles is not
particularly limited, but is preferably 0.2 to 5 !J.m, more preferably 0.3 to 4 !J.m, and
still more preferably 0.4 to 2.5 !J.m. When the average particle diameter of the nondoped
oxide particles is set to 0.2 to 5 !J.m, the crystal of the chemical conversion
25 treatment covering film to be formed (e.g., a crystal of an oxychloride such as a
phosphate) is likely to grow in a wedge form, and the adhesiveness between the resin
coating film and the coating treatment film can be further improved by the anchor
effect of the crystal of the chemical conversion treatment covering film.
[0044]
30 The "average particle diameter" of the non-doped oxide particles refers to
the average primary particle diameter in the case where the non-doped oxide
PCT/JP2016/060488
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particles existing in the resin coating fihn are present singly, and refers to the average
secondary particle diameter that indicates the particle diameter of the non-doped
oxide particle in cohesion in the case where non-doped oxide particles are present in
cohesion; and is preferably found by the following measurement method. First, the
5 surface-treated metal sheet on which the resin coating fihn is formed is cut to expose
a cross section thereof, and the cross section is polished. The cross section thus
obtained is observed with an electron microscope, and an observation image of the
cross section in the resin coating fihn is obtained. Several non-doped oxide
particles are selected from those present in the visual field of the observation image,
10 the length of the long side and the length of the short side of each oxide particle are
measured, the average value of the lengths of the long sides and the average value of
the lengths of the short sides are calculated, and these calculated values are further
averaged; thus, the average particle diameter is calculated.
The numerical value of the average particle diameter varies a little with the
15 measurement method. For example, it may vary with the measurement principle in
the case of using a particle size distribution meter, and with the image processing
method in the case of image analysis. However, the range of the particle diameter
of the non-doped oxide particle prescribed in the present specification is one taking
such variations into account, and the expected effect is stably obtained by a particle
20 diameter obtained by any method, provided that the particle diameter is in the range
prescribed in the present specification.
25
[0045]
The amount of non-doped oxide particles contained is 1 to 10 mass%
relative to the resin coating fihn (the total solid content of the coating fihn).
When the amount of non-doped oxide particles contained is less than 1
mass%, the component crystal of the chemical conversion treatment covering film to
be formed (e.g., a crystal of an oxychloride such as a phosphate) is less likely to be
formed in the interior of the outer layer of the resin coating fihn, and consequently it
is difficult to obtain the adhesiveness between the resin coating film and the coating
30 treatment fihn by the anchor effect of the chemical conversion treatment covering
fihn. On the other hand, when the amount of non-doped oxide particles contained
PCT/JP2016/060488
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is more than 1 0 mass%, the formation of the component crystal of the chemical
conversion treatment covering film to be formed may reach a maximum, and
accordingly the adhesiveness between the resin coating film and the coating
treatment film may reach a maximum; and the ratios of the electrically conductive
5 particles and the anti-corrosive particles in the resin coating fihn are reduced, and
consequently the properties of weldability, corrosion resistance before coating, etc.
may be insufficient.
The amount of non-doped oxide particles contained is preferably 2.5 to 7.5
mass% in terms of further improving the adhesiveness between the resin coating fihn
10 and the coating treatment film by the anchor effect of the crystal of the chemical
conversion treatment covering film.
[0046]
(Binder resin)
The binder resin serves as a binding agent that binds the components in the
15 resin coating film. The binder resin may be either of a water-soluble or waterdispersible
water-based resin that is dissolved or dispersed in water and a solventbased
resin that is dissolved or dispersed in an organic solvent, but is preferably a
water-based resin in terms of production cost and environmental compatibility.
[0047]
20 The water-based resin is not particularly limited, and examples include
water-soluble or water-dispersible resins such as a polyester resin, a urethane resin,
an acrylic resin, an epoxy resin, and a phenolic resin, and a mixed resin of two or
more of these resins.
In the case where a polyester resin is used as the water-based resin, the
25 molecular weight is preferably 10,000 to 30,000. If the molecular weight is less
than 10,000, it may be difficult to ensure sufficient processability. On the other
hand, if the molecular weight is more than 30,000, the area of the bonding site of the
resin itself is reduced, and it may be difficult to ensure excellent adhesiveness to a
coating treatment fihn. Furthermore, when crosslinking is performed using a
30 hardening agent such as melamine, the crosslinking reaction may not be sufficiently
produced, and performance as a resin coating film may be reduced.
PCT/JP2016/060488
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In the case where a urethane resin is used as the water-based resin, the
urethane resin is preferably in an emulsion form with an emulsion particle diameter
of 10 to 100 nm (more preferably 20 to 60 nm). When the emulsion particle
diameter is too small, the cost may be increased. On the other hand, when the
5 emulsion particle diameter is too large, the gap between emulsions may be increased
when the resin is made into a coating film, and barrier properties as a resin coating
film may be reduced. The type of the urethane resin is not particularly limited, and
examples include an ether-based type, a polycarbonate-based type, an ester-based
type, an acrylic graphite type, and the like. These may be used singly, or may be
10 used in combination.
[0048]
On the other hand, examples of the solvent -based resin include a polyester
resin, a urethane resin, an epoxy resin, and an acrylic resin, a mixed resin of two or
more of these resins, and the like.
15 [0049]
Here, the binder resin may be a crosslinked resin having a crosslinked
structure, or may be a non-crosslinked resin not having a crosslinked structure. The
binder resin is preferably a non-crosslinked resin in terms of forming the resin
coating film at low temperature.
20 The crosslinking agent (hardening agent) that provides the binder resin with
a crosslinked structure is preferably a water-soluble crosslinking agent. Specifically,
melamine, an isocyanate, and the like are preferable as the crosslinking agent. The
amount of the crosslinking agent added is not particularly limited, but is preferably 5
parts by mass to 30 parts by mass relative to I 00 parts by mass of the resin solid
25 content. If the amount of the crosslinking agent added is less than 5 parts by mass,
the crosslinking reaction with the resin may not proceed sufficiently, and
performance as a coating film may be insufficient. On the other hand, if the amount
of the crosslinking agent added is more than 30 parts by mass, the crosslinking
reaction may proceed excessively and the resin coating film may be excessively
30 hardened, and consequently processability may be reduced.
[0050]
PCT/JP20 16/060488
20171
The amount of the binder resin contained is not particularly limited, but is
preferably 20 to 80 mass% relative to the resin coating film (the total solid content of
the coating film).
When the amount of the binder resin contained is less than 20 mass%, the
5 function as a binder may not be exhibited, and the cohesive force of the resin coating
film may be reduced; hence, a fracture in the coating film (a cohesive failure of the
coating film) is likely to occur when an adhesiveness test or molding is performed.
If the amount of the binder resin contained is more than 80 mass%, the ratio of the
pigrnent component contained in the resin coating film is reduced, and it may be
10 difficult to achieve all of weldability, corrosion resistance, and post-coating
adhesiveness.
The amount of the binder resin contained is more preferably 25 to 70 mass%
and still more preferably 30 to 60 mass% relative to the resin coating film (the total
solid content of the coating film) in terms of bringing out the binder function and
15 achieving all of weldability, corrosion resistance, and the adhesiveness to a coating
treatment film.
[0051]
(Electrically conductive particles)
The electrically conductive particles contribute to the improvement of
20 weldability by providing the resin coating film with electrical conductivity. The
electrically conductive particles contained in the resin coating film are not
particularly limited, and examples include non-oxide ceramic particles, iron alloy
particles, stainless steel particles, particles of a material other than iron alloys (metal
particles, metal alloy particles, etc.), and the like.
25 The electrically conductive particles are preferably, among these, at least
one kind selected from the group consisting of non-oxide ceramic particles, iron
alloy particles, and stainless steel particles.
[0052]
Even in the case where the composition for resin coating formation is a
30 water-based composition, non-oxide ceramic particles and stainless steel particles are
less likely to be degraded in the composition, and can maintain high electrical
PCT/JP2016/060488
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conductivity. Thereby, excellent weldability of the surface-treated metal sheet can
be maintained for a long period of time.
In the case where the composition for resin coating formation is a waterbased
composition, iron alloy particles are inferior in stability in an alkaline water-
5 based composition, but are excellent in stability to some degree in an acidic waterbased
composition containing a certain kind of polyester resin or the like. Hence, in
the case where the composition for resin coating formation is an acidic water-based
composition, excellent weldability of the surface-treated metal sheet can be
maintained for a long period of time.
10 [0053]
First, the non-oxide ceramic particle is described.
The non-oxide ceramic that forms the non-oxide ceramic particle is not
particularly limited, but is preferably a non-oxide ceramic (a boride ceramic, a
carbide ceramic, a nitride ceramic, a silicide ceramic, or the like) of which the
15 electrical resistivity (volume resistivity, or specific resistance) at 25°C is in the range
ofO.l x 10" 6 to 185 x 10- 6 Ocm.
[0054]
Here, the non-oxide ceramic refers to a ceramic made of elements other than .
oxygen or a compound not containing oxygen. The boride ceramic, the carbide
20 ceramic, the nitride ceramic, and the silicide ceramic refer to non-oxide ceramics
containing boron B, carbon C, nitrogen N, and silicon Si as a main non-metal
constituent element, respectively. All of these are a non -oxide ceramic having an
electrical resistivity at 25°C of less than 0.1 x 10· 6 Ocm.
25
[0055]
Since the non-oxide ceramic particle has high electrical conductivity, the
contained amount for providing the resin coating film with sufficient electrical
conductivity is allowed to be a smaller amount. Consequently, the impact on the
corrosion resistance and moldability of the surface-treated metal sheet due to
containing electrically conductive particles is smaller. For reference, the electrical
30 resistivity of pure metals is in the range of 1.6 x 1 o· 6 Ocm (Ag simple substance) to
185 x 10· 6 Ocm (Mn simple substance); therefore, a non-oxide ceramic of which the
5
PCT/JP2016/060488
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electrical resistivity is in the range of 0.1 x 10· 6 to 185 x 10· 6 Ocm has excellent
electrical conductivity at a level substantially equal to that of pure metals.
[0056]
Here, examples of the non-oxide ceramic particle include the following.
Examples of the boride ceramic particle include a boride ceramic particle of
each transition metal of group IV (Ti, Zr, and Hf), group V (V, Nb, and Ta), and
group VI (Cr, Mo, and W) of the periodic table, Mn, Fe, Co, Ni, a rare earth element,
and group II (Ca, Sr, and Ba) other than Be or Mg.
However, particles of some boride ceramics of Be having an electrical
10 resistivity at 25°C of more than 185 x 10· 6 Ocm (e.g., Be2 B, BeB6 , etc.) have low
electrical conductivity, and may reduce the weldability of the surface-treated metal
sheet. Further, particles of boride ceramics of Mg (Mg3 Bz, MgBz, etc.) have low
stability to water or acid, and may reduce the weldability of the surface-treated metal
sheet.
15 [0057]
Examples of the carbide ceramic particle include a carbide ceramic particle
of each transition metal of group IV (Ti, Zr, and Hf), group V (V, Nb, and Ta), and
group VI (Cr, Mo, and W) of the periodic table, Mn, Fe, Co, and Ni. Particles of
carbide ceramics of rare earth elements and group II (e.g., YCz, LaCz, CeCz, PrCz,
20 Bez C, Mgz C3 , SrCz, etc.) are likely to be hydrolyzed in a moist atmosphere, and
may reduce the weldability of the surface-treated metal sheet.
[0058]
Examples of the nitride ceramic particle include a nitride ceramic particle of
each transition metal of group IV (Ti, Zr, and Hf), group V (V, Nb, and Ta), and
25 group VI (Cr, Mo, and W) of the periodic table, Mn, Fe, Co, and Ni. Particles of
nitrides of rare earth elements and group II (e.g., LaN, Mg3Nz, Ca3N2 , etc.) are
likely to be hydrolyzed in a moist atmosphere, and may reduce the weldability of the
surface-treated metal sheet.
30
[0059]
Examples of the silicide ceramic particle include a silicide particle of each
transition metal of group IV (Ti, Zr, and Hf), group V (V, Nb, and Ta), and group VI
PCT/JP2016/060488
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(Cr, Mo, and W) of the periodic table, Mn, Fe, Co, and Ni. Particles of silicides of
rare earth elements and group II (e.g., LaSi, Mgz Si, SrSiz, BaSh, etc.) are likely to
react with water to produce hydrogen in a moist atmosphere, and may reduce the
weldability of the surface-treated metal sheet.
5 [0060]
Further, examples of the non-oxide ceramic particle include a particle of a
mixture of two or more selected from the group consisting of these boride ceramics,
carbide ceramics, nitride ceramics, and silicide ceramics, a cermet particle obtained
by mixing these ceramics with a metal bonding material and performing sintering,
10 and the like.
[0061]
In the case of producing the resm coating film out of a water-based
composition, the standard electrode potential of the metal constituting a part of the
cermet particle is preferably -0.3 V or more. In the case where the standard
15 electrode potential of the metal constituting a part of the cermet particle is less than -
0.3 V, when the cermet particle exists in the water-based composition for a long
period of time, a rust layer or a thick oxide insulating layer is likely to be produced
on the surface of the particle, and the electrical conductivity of the particle may be
lost. Examples of the cermet particle having water degradation resistance include
20 WC-12Co, WC-12Ni, TiC-20TiN-15WC-l OMoz C-SNi, and the like. The standard
electrode potentials of Co and Ni are -0.28 V and -0.25 V, respectively, both of which
are nobler than -0.3 V, and therefore both metals have water degradation resistance.
[0062]
Here, among the non-oxide cerarmcs, Cr-based ceramics (CrB, CrB2 ,
25 Cr3 Cz, Cr2 N, CrSi, etc.) have a concern about environmental burdens, and Hf-based
ceramics (HfB2 , HfC, HJN, etc.) and most of the ceramics based on rare earth
elements on the heavier rare earth side than Tb are expensive and are not
commercially available; hence, a particle of a non-oxide ceramic other than these
ceramics, or a particle of a mixture of two or more of non-oxide ceramics other than
30 these ceramics is preferable.
[0063]
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Further, from the viewpoints of the presence or absence of industrial
products, stable distribution on home and abroad markets, prices, electrical resistivity,
etc., the non-oxide ceramic particle is more preferably the following non-oxide
ceramics, which are given as examples. That is, the non-oxide ceramic particle is
5 more preferably a particle of BaB6 (electrical resistivity: 77 x 1 o· 6 ncm), CeB6 (the
same: 30 x 10· 6 ncm), Co2 B (the same: 33 x 10· 6 ncm), CoB (the same: 76 x 10· 6
ncm), FeB (the same: 80 x 10· 6 ncm), GdB4 (the same: 31 x 10· 6 ncm), GdB6
(the same: 45 x 10· 6 ncm), LaB4 (the same: 12 x 10· 6 ncm), LaB6 (the same: 15 x
10·6 ncm), Mo2B (the same: 40 x 10·6 ncm), MoB (the same: 35 x 10·6 ncm),
10 MoBz (the same: 45 x 10· 6 Ocm), Moz Bs (the same: 26 x 10· 6 Ocm), Nb3 B2 (the
same: 45 x 10· 6 Ocm), NbB (the same: 6.5 x 10· 6 Ocm), Nb3 B4 (the same: 34 x
10"6 Ocm), NbB2 (the same: 10 x 10"6 Ocm), NdB4 (the same: 39 x 10"6 Ocm),
NdB6 (the same: 20 x 10· 6 Ocm), PrB4 (the same: 40 x 10· 6 Ocm), PrB6 (the
same: 20 x 10· 6 Ocm), SrB6 (the same: 77 x 10· 6 Ocm), TaB (the same: 100 x 10·6
15 Ocm), TaB2 (the same: 100 x 10·6 Ocm), TiB (the same: 40 x 10·6 Ocm), TiB2 (the
same: 28 x 10·6 Ocm), VB (the same: 35 x 10·6 Ocm), VB2 (the same: 150 x 10·6
Ocm), Wz Bs (the same: 80 x 10· 6 Ocm), YB4 (the same: 29 x 10· 6 Ocm), YB6
(the same: 40 x 10· 6 Ocm), YB12 (the same: 95 x 10· 6 Ocm), ZrB2 (the same: 60 x
10· 6 Ocm), MoC (the same: 97 x 10· 6 Ocm), MozC (the same: 100 x 10· 6 Ocm),
20 NbzC (the same: 144 x 10· 6 Ocm), NbC (the same: 74 x 10·6 Ocm), Ta2C (the
same: 49 x 10· 6 Ocm), TaC (the same: 30 x 10· 6 Ocm), TiC (the same: 180 x 10· 6
Ocm), Vz c (the same: 140 X 10" 6 Ocm), VC (the same: 150 X 10" 6 Ocm), we (the
same: 80 x 10· 6 Ocm), W 2 C (the same: 80 x 10· 6 Ocm), ZrC (the same: 70 x 10· 6
Ocm), Mo2N (the same: 20 x 10·6 Ocm), Nb2N (the same: 142 x 10·6 Ocm), NbN
25 (the same: 54 x 10· 6 Ocm), SeN (the same: 25 x 10· 6 Ocm), Ta2 N (the same: 135 x
10"6 Ocm), TiN (the same: 22 x 10" 6 Ocm), VN (the same: 160 x 10· 6 Ocm), ZrN
(the same: 14 x 10· 6 Ocm), CoSiz (the same: 18 x 10· 6 Ocm), Mo3 Si (the same: 22
x 10· 6 Ocm), Mo5 Si3 (the same: 46 x 10·6 Ocm), MoSi2 (the same: 22 x 10·6
Ocm), NbSiz (the same: 6.3 X 1 o· 6 Ocm), Niz Si (the same: 20 X 1 o· 6 Ocm), Taz Si
30 (the same: 124 x 10· 6 Ocm), TaSi2 (the same: 8.5 x 10· 6 Ocm), TiSi (the same: 63
x 10" 6 Ocm), TiSiz (the same: 123 x 10" 6 Ocm), V5 Sb (the same: 115 x 10·6
5
PCT/JP2016/060488
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Ocm), VSi2 (the same: 9.5 x 10· 6 Ocm), W3 Si (the same: 93 x 10· 6 Ocm), WSi2
(the same: 33 x 10· 6 Ocm), ZrSi (the same: 49 x 10· 6 Ocm), or ZrSi2 (the same: 76
x 1 o· 6 Ocm ), or a patticle of a mixture of two or more selected from these.
[0064]
The electrical resistivities additionally written in the parentheses of the nonoxide
ceramics given as examples are representative values (literature values) of
those on the market and in use as industrial materials. These electrical resistivities
increase or decrease with the type and amount of impurity elements that have entered
the crystal lattice of the non-oxide ceramic. Hence, these materials may be used
10 after checking that the electrical resistivity is in the range of 0.1 x 10"6 to 185 x 10"6
Ocm by, for example, actually measuring the electrical resistivity at 25°C using the
four-terminal four-probe method and the constant current application system in
accordance with JIS K7194, using a resistivity meter Loresta EP (MCP-T360 type)
and ESP probes (the diameter of the flat head portion of the terminal: 2 mm)
15 manufactured by Mitsubishi Chemical Analytech Co.,Ltd.
[0065]
Next, the iron alloy particle is described.
The iron alloy particle is an alloy particle of an alloy of at least one selected
from the group consisting of Si, V, Mn, W, Mo, Ti, Ni, and Nb, and iron. Examples
20 of the iron alloy powder include ferrosilicon, ferrovanadium, ferromanganese,
ferrotungsten, ferromolybdenum, ferrotitanium, ferronickel, ferroboron,
ferroniobium, and the like.
Among these, ferrovanadium, ferrosilicon, and ferromanganese are
preferable as the iron alloy particle from the viewpoint of corrosion resistance, as
25 well as weldability.
[0066]
The stainless steel particle will now be described.
The stainless steel particle is an alloy particle in which 10.5 mass% or more
Cr is put in Fe (an alloy particle in which the amount of C contained is 1.2 mass% or
30 less).
[0067]
PCT/JP2016/060488
26171
Next, the properties of the electrically conductive particle described above
are described.
The shape of the electrically conductive particle is not particularly limited,
but is preferably, for example, a shape close to a sphere, such as a spherical shape, a
5 quasi-spherical shape (e.g., an ellipsoidal shape, a hen's egg-like shape, a rugby balllike
shape, etc.), or a polyhedral shape (e.g., a soccer ball-like shape, a die-like shape,
brilliant cut shapes of various jewels, etc.). Electrically conductive particles having
a shape close to a sphere are uniformly dispersed in the resin coating film, and easily
form an effective current path penetrating in the thickness direction of the resin
10 coating film; and consequently further improve the joinability of the surface-treated
metal sheet. On the other hand, electrically conductive particles of a long, thin
shape (e.g., a bar-like shape, a needle-like shape, a fibrous shape, etc.) or a planar
shape (e.g., a flake-like shape, a flat sheet-like shape, a thin leaf-like shape, etc.) may,
in the formation process of the resin coating film, be arranged parallel to the surface
15 of the coating film or be deposited near the interface between the metal sheet (in the
case where underlayer treatment is performed on the surface of the metal sheet, the
underlayer treatment layer) and the resin coating film; and this makes it difficult to
form an effective current path penetrating in the thickness direction of the resin
coating film, and may reduce the joinability of the surface-treated metal sheet.
20 [0068]
The average particle diameter of the electrically conductive particles is not
particularly limited, but is preferably 0.2 to 5 J.Lm and more preferably 0.5 to 2.5 J.Lm.
When the average particle diameter of the electrically conductive particles is in the
range of 0.2 to 5 J.Lm, an effective current path penetrating in the thickness direction
25 of the resin coating film is easily formed, and the joinability of the surface-treated
metal sheet is further improved.
Here, the "average particle diameter" of the electrically conductive particles
refers to the average primary particle diameter in the case where the electrically
conductive particles existing in the resin coating film are present singly, and refers to
30 the average secondary particle diameter that indicates the particle diameter of the
electrically conductive particle in cohesion in the case where electrically conductive
PCT/JP2016/060488
27171
particles are present in cohesion; and is preferably found by the following
measurement method. First, the surface-treated metal sheet on which the resin
coating film is formed is cut to expose a cross section thereof, and the cross section is
polished. The cross section thus obtained is observed with an electron microscope,
5 and an observation image of the cross section in the resin coating film is obtained.
Several particles of the pigment are selected from those present in the visual field of
the observation image, the length of the long side and the length of the short side of
each electrically conductive particle are measured, the average value of the lengths of
the long sides and the average value of the lengths of the short sides are calculated,
10 and these calculated values are further averaged; thus, the average particle diameter
is calculated.
[0069]
Preferred aspects of the electrically conductive particle are further described.
The electrically conductive particles preferably include two or more kinds
15 of particles of non-oxide ceramic particles and at least one kind selected from the
group consisting of iron alloy particles and stainless steel particles. The mass ratio
between the non-oxide ceramic particles and the at least one kind selected from the
group consisting of iron alloy particles and stainless steel particles (non-oxide
ceramic particles/at least one kind selected from the group consisting of iron alloy
20 particles and stainless steel particles) is preferably 1/9 to 8/2, more preferably 1/9 to
7/3, and stillmore preferably 2/8 to 6/4.
When at least one kind selected from the group consisting of iron alloy
particles and stainless steel particles are used in combination with non-oxide ceramic
particles at a ratio in the range mentioned above as the electrically conductive
25 particles, the electrical conductivity of the resin coating film is enhanced, and the
weldability of the surface-treated metal sheet is further improved. Furthermore, the
amount of non-oxide particles with high hardness contained can be reduced. When
resistance welding is continuously performed, the occurrence of a phenomenon in
which electrically conductive particles get stuck in an electrode is suppressed; thus,
30 during continuous welding, the occurrence of welding failure etc. is suppressed.
[0070]
PCT/JP2016/060488
28171
Next, the amount of electrically conductive particles contained is described.
The amount of electrically conductive particles contained is 5 to 30 mass%
relative to the resin coating film (the total solid content of the coating film).
When the amount of electrically conductive particles contained is less than 5
5 mass%, the weldability of the surface-treated metal sheet is not sufficiently obtained.
When the amount of electrically conductive particles contained is more than 30
mass%, the cohesive force of the coating film is reduced, and accordingly the
adhesiveness to a coating treatment film is reduced.
The amount of electrically conductive particles contained is preferably 10 to
10 20 mass% relative to the resin coating film (the total solid content of the coating
film) in terms ofweldability, coating adhesiveness, etc.
[0071]
(Anti-corrosive particles)
The resin coating film preferably contains anti-corrosive particles. The
15 anti-corrosive particles can improve the corrosion resistance of particularly the
surface of the metal sheet adjacent to the resin coating film of the surface-treated
metal sheet.
The anti-corrosive particles that can be contained in the resin coating film is
not particularly limited, but preferably contains at least one selected from the group
20 consisting of aluminum tripolyphosphate, Zn, Mg, AI, Ti, Zr, and Ce salts of
phosphoric acid and phosphorous acid, hydrocalumite-treated phosphoric acid
compounds (as an example, EXPERT NP-530 NS produced by Toho Ganryo Kogyo
Co.,Ltd., which is hydrocalurnite-treated zinc phosphate), Ca ion exchange silica,
and amorphous silica with an oil absorption of 100 to 1000 mill 00 g, a specific
25 surface area of200 to 1000 m2/g, and an average particle diameter of2 to 30 flm.
[0072]
A preferred anti-corrosive particles are, among these, a phosphate-based
anti-corrosive particles (aluminum tripolyphosphate, a hydrocalumite-treated
phosphoric acid compound, etc.) or a silica-based anti-corrosive particles, or a
30 combination of both from the viewpoint of achieving the corrosion resistance of both
the flawed portion and the flat surface portion. In particular, a preferred antiPCT/
JP2016/060488
29/71
corrosive particles are at least one selected from the group consisting of aluminum
tripolyphosphate, a hydrocalumite-treated phosphoric acid compound, Ca exchange
silica, and amorphous silica with an oil absorption of 100 to 1000 mill 00 g, a
specific surface area of200 to 1000 m2/g, and an average particle diameter of2 to 30
5 !!ill.
[0073]
In the case where the resin coating film contains zinc oxide particles, the
resm coating film preferably contains, as anti-corrosive particles, aluminum
dihydrogen tripolyphosphate containing Mg. Examples of the aluminum
10 dihydrogen tripolyphosphate containing Mg include magnesium-treated aluminum
dihydrogen tripolyphosphate, a mixture of aluminum tripolyphosphate and
magnesium hydroxide, and the like. It is presumed that, by aluminum dihydrogen
tripolyphosphate containing Mg being contained in the resin coating film, zinc oxide
particles, Mg, and aluminum dihydrogen tripolyphosphate react together to form a
15 composite oxide and a composite compound of Zn-Mg and a Zn-phosphoric acid
compound, and thereby excellent corrosion resistance is provided.
[0074]
The oil absorption of silica can be measured in accordance with JIS K 5101-
13-2. The specific surface area of silica can be measured by the BET method.
20 The average particle diameter of silica can be measured by a method similar to the
method for the average particle diameter of the electrically conductive particles.
25
[0075]
The amount of the anti-corrosive particles contained is preferably 5 to 40
mass% relative to the resin coating film (the total solid content of the coating film).
When the amount of the anti-corrosive particles contained is less than 5
mass%, corrosion resistance may not be sufficiently obtained. When the amount of
the anti-corrosive particles contained is more than 40 mass%, the processability of
the coating film may be reduced, and cohesive force may be reduced.
The amount of the anti-corrosive particles contained is more preferably 7.5
30 to 35 mass% and still more preferably 10 to 30 mass% relative to the resin coating
film (the total solid content of the coating film) in terms of corrosion resistance and
processability.
[0076]
(Other additives)
PC'l'/JP2016/060488
30171
The resin coating film may contain other additives. Examples of the other
5 additive include known additives such as an extender pigment, a solid lubricant, and
a leveling agent.
[0077]
Examples of the extender pigment include silica (including colloidal silica),
titania, zirconia, and the like.
10 [0078]
The solid lubricant can provide the resm coating film with excellent
lubricity, and can improve powdering resistance. Examples of the solid lubricant
include the solid lubricants of (1) and (2) below.
(1) Polyolefm wax and paraffm wax: for example, polyethylene wax, synthetic
15 paraffm, natural paraffin, microcrystalline wax, a chlorinated hydrocarbon, and the
like
(2) Fluorine resin-based wax: for example, a polyfluoroethylene resm (a
polytetrafluoroethylene resin, etc.), a polyvinyl fluoride resin, a polyvinylidene
fluoride resin, and the like
20 [0079]
The average particle diameter of the solid lubricant is preferably 0.05 to 25
f.Lm. When the average particle diameter of the solid lubricant is less than 0.05 f.Lm,
the area of the lubricant occupying the outer layer of the resin coating film tends to
be large due to the surface concentration of the lubricant, and the adhesiveness
25 between the resin coating film and the coating treatment film may be reduced. On
the other hand, when the average particle diameter of the solid lubricant is more than
25 f.Lm, the lubricant is likely to fall off from the resin coating film, and a prescribed
lubricity may be difficult to obtain and corrosion resistance may be reduced. The
average particle diameter of the solid lubricant is more preferably 1 to 15 f.Lm and
30 still more preferably 3 to 10 f.Lm in terms of obtaining excellent coating material
adhesiveness, corrosion resistance, lubricity, and powdering resistance.
PCT/JP20 16/060488
31171
[0080]
The softening point of the solid lubricant is preferably 100°C to 135°C and
more preferably 110 to 130°C. When the softening point of the solid lubricant is
I oooc to 135°C, lubricity and powdering resistance are further improved.
5 [0081]
The amount of the solid lubricant contained is preferably 0.1 to 10 mass%
relative to the resin coating film (the total solid content of the coating film). When
the amount of the solid lubricant contained is less than 0.1 mass%, lubricity may not
be sufficiently obtained. When the amount of the solid lubricant contained is more
10 than 10 mass%, the adhesiveness between the resin coating film and the coating
treatment film and corrosion resistance may be reduced.
The amount of the solid lubricant contained is more preferably 0.2 to 5
mass% and still more preferably 0.5 to 2.5 mass% relative to the resin coating film
(the total solid content of the coating film) in terms of the adhesiveness between the
15 resin coating film and the coating treatment film, lubricity, and corrosion resistance.
[0082]
(Amount of resin coating film attached)
The amount of the resin coating film attached (the amount of the total solid
content of the resin coating film attached) is 2 to 20 g/m2
• When the amount of the
20 resin coating film attached is less than 2 g/m2
, the adhesiveness between the resin
coating film and the coating treatment film and corrosion resistance are not
sufficiently obtained. When the amount of the resin coating film attached is more
than 20 g/m2
, the reduction in the cohesive force of the coating film and weldability
are not sufficiently obtained.
25 The amount of the resin coating film attached is preferably 2 to 15 g/m2 in
30
terms of the adhesiveness between the resin coating film and the coating treatment
film, weldability, and corrosion resistance.
[0083]
(Formation of resin coating film)
The method for forming the resin coating film is not particularly limited,
and known methods may be used. For example, a composition for resin coating
PCT/JP2016/060488
32171
formation in which a binder resm, electrically conductive particles, and oxide
particles, and anti-corrosive particles and other additives as necessary, are mixed in a
solvent is obtained. The solvent may be water or an organic solvent, but is
preferably water in terms of production cost and environmental compatibility. That
5 is, the composition for resin coating fom1ation is preferably a water-based
composition. Then, the composition for resin coating formation is applied onto at
least one surface of a metal sheet, and drying and heating are performed; thus, a resin
coating film can be formed.
[0084]
10 (Other aspects of surface-treated metal sheet)
15
In the surface-treated metal sheet, a known functional film, such as an
underlayer treatment covering f!lm that further improves the adhesiveness of the
coating film to the metal sheet, corrosion resistance, etc., may be interposed between
the metal sheet and the resin coating film.
The underlayer treatment covering film may be a chromate treatment
covering film or an underlayer treatment covering film containing practically no
chromium (a chromate-free treatment covering f!lm). Typical examples of the
chromate-free treatment liquid are a silica-based treatment liquid containing a silicon
compound such as liquid phase silica, gas phase silica, or a silicate as a main
20 covering component, and a zircon-based treatment liquid containing a zircon-based
compound as a main covering component. These treatment liquids· may be a
treatment liquid in which an organic resin is made to coexist with a main covering
component. The chromate-free treatment liquid is not linllted to a silica-based
treatment liquid or a zircon-based treatment liquid. As the chromate-free treatment
25 liquid, various chromium-free treatment liquids for use in coating underlayer
treatment are proposed and are expected to be proposed in the future, as well as
silica-based treatment liquids and zircon-based treatment liquids. Also such
chromium-free treatment liquids may be used.
For the amount of the underlayer treatment covering film attached, an
30 appropriate attached amount may be selected in accordance with the treatment liquid
used. For example, in the case of an underlayer treatment covering film based on a
5
PCT/JP2016/060488
33171
silica-based treatment liquid, a normal attached amount is preferably in the range of
1 to 20 mg/m2 on a Si basis.
[0085]

Next, a coated member according to the fust embodiment is described.
The coated member according to the first embodiment includes a molded
material using the surface-treated metal sheet according to the fust embodiment
mentioned above as the material, a chemical conversion treatment covering fihn
located on the coating film (the resin coating fihn) of the molded material, and a
10 coating treatment fihn located on the chemical conversion treatment covering film.
[0086]
The molded material is obtained by molding the surface-treated metal sheet
described above as the material. The shape of the molded material is not
particularly limited, and may have a shape in accordance with the use of the coated
15 member. The molded material may be one in which a plurality of surface-treated
metal sheets are joined by welding, adhesion, or the like. Since the surface-treated
metal sheet according to the present embodiment is excellent in weldability, a defect
such as a crack due to welding is prevented even in the case where the molded
material is welded.
20 [0087]
The chemical conversion treatment covering fihn is a fihn that is located on
the resin coating fihn and is formed by performing chemical conversion treatment on
the surface of the resin coating fihn. The chemical conversion treatment covering
film is not particularly limited, but is preferably, for example, a covering film
25 containing a phosphate. Such a covering fihn containing a phosphate tends to have
a structure like that shown in FIG. lB and FIG. lC described above because the
surface of the resin coating fihn comes into contact with an acidic chemical
conversion treatment liquid during the formation.
[0088]
30 Examples of the phosphate include a crystalline or amorphous phosphate.
A crystalline phosphate is preferable from the viewpoint of causing a wedge-form
PCT/JP2016/060488
34171
phosphate to exist in the chemical conversion treatment covering film.
[0089)
Examples of the crystalline phosphate include zmc phosphate (hopeite,
Zn3(P04)2·4H20), zinc iron phosphate (phosphophyllite, ZnzFe(P04)z·4HzO),
5 manganese phosphate (hureaulite, Mns(P03(0H))z(P04)z-4Hz0), manganese iron
phosphate ((Mnl·xFex)sHz(P04)4-4HzO; in the formula, x indicates that the iron-based
metal material is etched during chemical conversion treatment and the iron
component is contained in the covering film; 0 < x < 1 ), calcium zinc phosphate
(scholzite, CaZnz(P04)z·2HzO), and the like.
10 Examples of the amorphous phosphate include iron phosphate, tin
phosphate, zirconium phosphate, titanium phosphate, hafnium phosphate, and the
like.
[0090]
The chemical conversion treatment covermg film may be formed of
15 components other than a phosphate. For example, the chemical converswn
treatment covering film may contain a salt of at least one selected from iron, titanium,
zirconium, hafnium, indium, tin, bismuth, vanadium, nickel, cerium, molybdenum,
and tungsten, and a nitrate ion, a sulfate ion, a fluoride ion, a complex fluoride ion, or
a carbonate ion. Specific examples of the salt include titanium oxide, zirconium
20 oxide, hafnium oxide, indium oxide, tin oxide, bismuth oxide, vanadium oxide,
nickel oxide, cerium oxide, molybdenum oxide, tungsten oxide, iron sulfide,
zirconium fluoride, titanium fluoride, hafnium fluoride, indium fluoride, and the like.
[0091]
The thickness of the chemical converswn treatment covering film is
25 preferably 0.01 J.Ull to 3 J.Ull, more preferably 0.03 J.lm to 2 J.lm, and still more
preferably 0.05 J.lm to 1 J.lm.
In the case where the chemical conversion treatment covering film contains
a crystalline salt, discussing the thickness is not appropriate because the covering
film has unevenness caused by the crystal. On the other hand, it is possible to focus
30 on the crystal diameter of the chemical conversion treatment covering film. The
crystal diameter of the crystalline phosphate is preferably 0.10 to 5 J.lm, more
35171
preferably 0.30 to 4 )lm, and still more preferably 0.50 to 3 )lm.
[0092]
PCT/JP2016/060488
The coating treatment film is located on the chemical conversion treatment
covering film. The coating treatment film is a film formed by a known coating
5 treatment such as electrodeposition coating, powder coating, or solvent coating.
10
The coating treatment film may be one layer, or may be multiple layers (for example,
a coating treatment film composed of an under-coating layer, an intermediate coating
layer, and an over-coating layer, or the like).
[0093]
Since the molded material includes the prescribed resin coating film and the
coating treatment film is formed on the resin coating film via the chemical
conversion treatment covering film, the coated member described above is excellent
in the adhesiveness between the resin coating film and the coating treatment film.
Furthermore, since the surface-treated metal sheet according to the present
15 embodiment is excellent also in weldability, a defect such as a crack due to welding
is prevented even in the case where the coated member is welded.
[0094]
The coated member according to the first embodiment is not particularly
limited, and can be widely used for, for example, automobile members (automobile
20 bodies, suspension system members, etc.), machine members (casings, etc.), home
electrical appliance members (casings, etc.), building materials (roofs, walls, etc.),
etc.
25
[0095]

Next, a method for producing the coated member according to the first
embodiment is described.
The method for producing the coated member according to the present
embodiment includes a step of performing chemical conversion treatment on a
molded material obtained by molding the surface-treated metal sheet described above
30 and forming a chemical conversion treatment covering film on the coating film (a
first step) and a step of forming a coating treatment film on the chemical conversion
treatment covering film (a second step).
[0096]
36171
PCT/JP2016/060488
First, prior to the first step, a molded material is prepared. The molded
material is obtained by molding the surface-treated metal sheet according to the first
5 embodiment described above into a target shape. The surface-treated metal sheet
may be molded using, for example, known molding techniques such as cutting and
press molding. The molded material may be fashioned into a desired shape by
welding (spot welding or the like), as necessary.
A known treatment such as degreasing or surface conditioning may be
10 performed on the resin coating film of the molded material on which chemical
conversion treatment is to be performed.
[0097]
Next, chemical conversion treatment is performed on the molded material to
form a chemical conversion treatment covering film on the resin coating film. The
15 chemical conversion treatment liquid used for chemical conversion treatment and the
treatment conditions may be selected in accordance with the condition and
composition of the chemical conversion treatment covering film to be formed, as
appropriate.
20
[0098]
For example, in the case where the chemical conversion treatment covering
film contains a crystalline phosphate, an acidic aqueous solution containing a
phosphate ion as an anion and containing at least one selected from zinc, calcium,
and manganese as a cation may be used as the chemical conversion treatment liquid.
For the purpose of enhancing the reaction rate, it is preferable that ions of a transition
25 metal such as nickel or cobalt, an oxidizing agent such as nitric acid or nitrous acid,
or an etchant component such as fluoride ions or complex fluoride ions be further
added to the acidic aqueous solution. As acidic aqueous solutions for phosphate
treatment in which the types and contained amounts of the anions and the cations
mentioned above are appropriately combined, commercially available ones may be
30 used as they are, and examples include "Palbond 860," "Palbond L3020," "Palfos
MIA," "Palfos MS," "Palbond 880," "Palbond SX35," "Palbond L47," and "Ferricoat
37/71
7" produced by Nihon Parkerizing Co.,Ltd., and the like.
[0099]
PCT/JP2016/060488
The pH of the chemical conversion treatment liquid mentioned above is not
particularly limited, but is preferably 1.0 to 5.0 and more preferably 2.0 to 4.0.
5 [0100]
The temperature during chemical conversiOn treatment of the chemical
conversion treatment liquid mentioned above is not particularly limited, but is
preferably 30°C to 120°C, more preferably 35°C to 1!0°C, and still more preferably
40°C to 100°C. The time of chemical conversion treatment is not particularly
10 limited, and may be selected in accordance with the target attached amount of the
chemical conversion treatment covering film to be formed, as appropriate.
[0101]
In the case where the chemical conversion treatment covering film contains
an amorphous phosphate, an acidic aqueous solution containing a phosphate ion as
15 an anion and containing at least one selected from iron, tin, zirconium, titanium, and
hafuium as a cation may be used as the chemical conversion treatment liquid, for
example. For the purpose of enhancing the reaction rate, it is preferable that ions of
a transition metal such as nickel or cobalt, an oxidizing agent such as nitric acid or
nitrous acid, or an etchant component such as .fluoride ions or complex fluoride ions
20 be further added to the acidic aqueous solution. As acidic aqueous solutions for
phosphate treatment in which the types and contained amounts of the anions and the
cations mentioned above are appropriately combined, commercially available ones
may be used as they are, and examples include "Palfos 1077," "Palfos 525T," and
"Palfos K5100" produced by Nihon Parkerizing Co.,Ltd., and the like. The pH of
25 the chemical conversion treatment liquid mentioned above is not particularly limited,
but is preferably 1.0 to 5.0 and more preferably 2.0 to 4.0.
[0102]
As another chemical conversion treatment liquid for forming the chemical
conversion treatment covering film, an acidic aqueous solution containing at least
30 one selected from a nitrate ion, a sulfate ion, a fluoride ion, a complex fluoride ion,
and a carbonate ion as an anion and containing at least one selected from iron,
PCT/JP2016/060488
38171
titanium, zirconium, hafnium, indium, tin, bismuth, vanadium, nickel, cenum,
molybdenum, and tungsten as a cation may be used. Such an acidic aqueous
solution can be prepared by appropriately combining the types and contained
amounts of compounds corresponding to the anions and the cations mentioned above,
5 or can be obtained by using commercially available ones as they are. The pH of the
chemical conversion treatment liquid mentioned above is not particularly limited, but
is preferably 1.0 to 5.0 and more preferably 2.0 to 4.0.
[0103]
The temperature during chemical converswn treatment of the chemical
10 conversion treatment liquid in the case of forming a chemical conversion treatment
covering film containing an amorphous phosphate or other chemical conversion
treatment covering films is not particularly limited, but is preferably 10°C to 100°C,
more preferably 15°C to 80°C, and still more preferably 20°C to 60°C. The time of
chemical conversion treatment is not particularly limited, and may be selected in
15 accordance with the target attached amount of the chemical conversion treatment
covering film to be formed, as appropriate.
[0104]
Next, coating treatment is performed on the resin coating film of the molded
material that has undergone chemical conversion treatment. Thereby, a coating
20 treatment film is formed on the resin coating film that has undergone chemical
conversion treatment. A known coating treatment such as electrodeposition coating,
powder coating, or solvent coating is used as the coating treatment. 1n the case
where the coating treatment film is composed of a plurality of layers, the coating
treatment film can be formed by performing coating treatment multiple times.
25 [0105]
The coated member according to the first embodiment can be produced
through these steps.
[0106]
II. Second embodiment
30 Next, a surface-treated metal sheet according to a second embodiment is
described.
5
10
15
PCT/JP2016/060488
39171
[01 07]

The surface-treated metal sheet according to the second embodiment
includes a metal sheet and
a coating film placed on at least one major surface of the metal sheet,
in which the coating film contains oxide particles, a binder resin, and
electrically conductive particles,
the amount of the electrically conductive particles contained ts 5 to 30
mass% relative to the coating film,
the oxide particles include at least doped oxide particles,
the doped oxide particles include at least one kind selected from the group
consisting of doped zinc oxide particles and doped tin oxide particles,
the amount of the oxide particles contained is 1 to 30 mass% relative to the
coating film, and
the amount of the coating film attached to the major surface is 2 to 20 g/m2
.
[0108]
The surface-treated metal sheet according to the second embodiment is
excellent in both the adhesiveness to a coating treatment film after coating and
weldability by virtue of the configuration mentioned above. The reason is
20 presumed to be as follows.
[0109]
As described above, on the resin coating film of the surface-treated metal
sheet, chemical conversion treatment is generally performed before coating is
performed, and a chemical conversion treatment covering film is formed. A typical
· 25 example of the chemical conversion treatment covering film is an oxychloride
covering film such as a phosphate covering film, and the chemical conversion
treatment liquid for forming the oxychloride covering film such as a phosphate
covering film exhibits acidity (e.g., a pH of2 to 3).
When the prescribed contained amount mentioned above of doped oxide
30 particles described above are put in the resin coating film of the surface-treated metal
sheet, the doped oxide particles are present in a state where some of them are
PCT/JP2016/060488
40171
exposed on the surface of the resin coating film and others are dispersed in the
interior of the outer layer of the resin coating film (see FIG. lA). The doped oxide
particles described above have the property of being dissolved in an acidic solution
(e.g., a pH of2 to 3), similarly to the non-doped oxide particles described above.
5 [OliO]
Hence, when chemical conversion treatment with an acidic chemical
conversion treatment liquid is performed on the resin coating film containing doped
oxide particles, the doped oxide particles exposed on the surface of the resin coating
film are dissolved by the acidic chemical conversion treatment liquid. Then, the pH
10 of their vicinity increases, and components of the chemical conversion treatment
liquid (e.g., an oxychloride such as a phosphate) deposit and grow. Thereby, a
chemical conversion treatment covering film is formed. It is presumed that at this
time also the doped oxide particles existing in the interior of the outer layer of the
resin coating film are dissolved by the acidic chemical conversion treatment liquid,
15 and components of the chemical conversion treatment liquid enter the interior of the
outer layer of the resin coating film and deposit, and grow in a wedge form so as to
protrude from the interior to the surface of the outer layer of the resin coating film
(see FIG. lB). When a coating treatment film based on coating is formed on the
chemical conversion treatment covering film in this state (see FIG. 1 C), the
20 adhesiveness between the resin coating film and the coating treatment film (in
particular, the secondary adhesiveness after a warm salt water test) is further
enhanced by, in addition to the high adhesiveness by the chemical conversion
treatment covering film itself, the anchor effect by a crystal of the chemical
conversion treatment covering film that has grown in a wedge form (e.g., a crystal of
25 an oxychloride such as a phosphate).
[Olll]
Here, the presence or absence of a crystal of the chemical conversion
treatment covering film (e.g., a crystal of an oxychloride such as a phosphate) can be
checked by surface observation with a scanning electron microscope (SEM) or from
30 diffraction peaks obtained by X-ray diffraction analysis.
[0112]
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In addition, the doped oxide particles have electrical conductivity; thus, by
putting in doped oxide particles in the range mentioned above, not only the
adhesiveness between the resin coating film and the coating treatment film but also
the electrical conductivity of the resin coating film is increased, and also weldability
5 is improved.
The effects of the adhesiveness between the resin coating film and the
coating treatment film and weldability by the doped oxide particles are improved by
setting the attached amount of the resin coating film in the range mentioned above.
Furthermore, by putting electrically conductive particles in the range mentioned
10 above in the resin coating film, electrical conductivity is increased, and also excellent
weldability is obtained.
[0113]
From the above, it is presumed that the surface-treated metal sheet
according to the second embodiment is excellent in both the adhesiveness to a
15 coating treatment fihn after coating and weldability by virtue of the configuration
mentioned above.
In the second embodiment, in FIG. I, I 0 represents the resin coating film,
12 represents the doped oxide particle, 14 represents the crystal of the chemical
conversion treatment covering fihn (e.g., a crystal of an oxychloride such as a
20 phosphate), and 16 represents the coating treatment film.
[0114]
In the surface-treated metal sheet according to the second embodiment, anticorrosive
particles may be contained in the resin coating film. The anti-corrosive
particles, depending on its type, are dissolved by an acidic chemical conversion
25 treatment liquid. However, when oxide particles are put in the resin coating fihn
along with the anti-corrosive particles, the oxide particles are actively dissolved by
the acidic chemical conversion treatment liquid, and accordingly the anti-corrosive
particles are dissolved less easily. Thereby, corrosion resistance is easily improved.
[0115]
30 In the surface-treated metal sheet according to the second embodiment, the
resin coating fihn may be formed on both surfaces (both major surfaces) of the metal
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sheet, or may be formed only on one surface (one major surface) of the metal sheet,
in accordance with the use. The resin coating film may be formed on part of the
surface of the metal sheet, or the entire surface of the metal sheet may be covered.
The part of the metal sheet where the resin coating film is formed is excellent in the
5 adhesiveness to a coating treatment film and resistance weldability. The part is
excellent also in corrosion resistance and moldability.
[0116]
The surface-treated metal sheet according to the second embodiment will
now be described in detail. However, the surface-treated metal sheet according to
10 the second embodiment has the same configuration as the surface-treated metal sheet
according to the first embodiment except that, in place of the prescribed non-doped
oxide particles mentioned above, doped oxide particles are contained in the resin
coating film. Hence, a description of the same configuration is omitted.
[0117]
15 (Oxide particles)
20
In the present embodiment, the oxide particles include doped oxide particles.
The oxide particles to be doped include at least one kind selected from the
group consisting of zinc oxide particles and tin oxide particles.
[0118]
The doped oxide particles may be, in the case of doped zinc oxide as an
example, a particle in which an oxide particle is doped with at least one element
selected from the group consisting of the group 13 elements of the periodic table and
the group 15 elements of the periodic table (hereinafter, occasionally referred to as a
"dopant element") and is thereby provided with electrical conductivity.
25 Examples of the group 13 element of the periodic table include B, AI, Ga, In,
etc. Examples of the group 15 element of the periodic table include P, As, etc.
Among these, Al, Ga, and Sb are preferable as the dopant element in terms of
improving electrical conductivity. For zinc oxide, AI is more preferable from the
viewpoint of cost.
30 [0119]
For tin oxide, antimony-doped tin oxide (ATO), phosphorus-doped tin oxide
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(PTO), niobium-doped tin oxide (NbTO), tantalum-doped tin oxide (TaTO), fluorinedoped
tin oxide (FTO), and the like are given.
[0120]
The amount of the dopant element contained is preferably 0.05 to 5
5 atomic% and more preferably 0.1 to 5 atomic% relative to the undoped oxide particle
in terms of improving electrical conductivity.
[0121]
The doped oxide particles, after dissolved by the chemical conversion
treatment liquid, promote the growth of the crystal of the chemical conversion
10 treatment covering fihn (e.g., a crystal of an oxychloride such as a phosphate);
therefore, the adhesiveness between the resin coating film and the coating treatment
film can be further improved by the anchor effect of the crystal of the chemical
conversion treatment covering fihn.
The doped oxide particles, after dissolved by the chemical conversion
15 treatment liquid, are incorporated into the chemical conversion treatment covering
film.
Furthermore, in addition to the improvement in corrosion resistance in
association with the chemical conversion treatment formation mentioned above, the
doped oxide particles have electrical conductivity, and can therefore act also as an
20 electrically conductive pigment; thus, electrical conductivity can be improved.
[0122]
The average particle diameter of the doped oxide particles is preferably 0.2
to 5 J-Lm, more preferably 0.3 to 4 J-Lm, and still more preferably 0.4 to 2.5 J-Lm.
When the average particle diameter of the doped oxide particles is set to 0.2 to 5 J-Lm,
25 the crystal of the chemical conversion treatment covering fihn to be formed (e.g., a
crystal of an oxychloride such as a phosphate) is likely to grow in a wedge form, and
the adhesiveness between the resin coating fihn and the coating treatment fihn can be
further improved by the anchor effect of the crystal of the chemical conversion
treatment covering film.
30 [0123]
The "average particle diameter" of the doped oxide particles refers to the
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average primary particle diameter m the case where the doped oxide particles
existing in the resin coating film are present singly, and refers to the average
secondary particle diameter that indicates the particle diameter of the doped oxide
particle in cohesion in the case where doped oxide particles are present in cohesion;
5 and is preferably found by the following measurement method. First, the surfacetreated
metal sheet on which the resin coating film is formed is cut to expose a cross
section thereof, and the cross section is polished. The cross section thus obtained is
observed with an electron microscope, and an observation image of the cross section
in the resin coating film is obtained. Several doped oxide particles are selected
10 from those present in the visual field of the observation image, the length of the long
side and the length of the short side of each oxide particle are measured, the average
value of the lengths of the long sides and the average value of the lengths of the short
sides are calculated, and these calculated values are further averaged; thus, the
average particle diameter is calculated.
15 [0124]
The numerical value of the average particle diameter varies a little with the
measurement method. For example, it may vary with the measurement principle in
the case of using a particle size distribution meter, and with the image processing
method in the case of image analysis. However, the range of the particle diameter
20 of the doped oxide particle prescribed in the present specification is one taking such
variations into account, and- the expected effect is stably obtained by a particle
diameter obtained by any method, provided that the particle diameter is in the range
prescribed in the present specification.
25
[0125]
Also in the surface-treated metal sheet according to the second embodiment,
the resin coating film may contain "at least one kind of oxide particles selected from
the group consisting of zinc oxide particles, magnesium oxide particles, calcium
oxide particles, tin oxide particles, and strontium oxide particles" in the resin coating
film of the surface-treated metal sheet according to the first embodiment.
30 [0126]
The amount of oxide particles contained is 1 to 30 mass% relative to the
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resin coating film (the total solid content of the coating film).
When the amount of oxide particles contained is less than 1 mass%, the
component crystal of the chemical conversion treatment covering film to be formed
(e.g., a crystal of an oxychloride such as a phosphate) is less likely to be formed in
5 the interior of the outer layer of the resin coating film, and consequently it is difficult
to obtain the adhesiveness between the resin coating film and the coating treatment
film by the anchor effect of the chemical conversion treatment covering film.
Furthermore, also weldability is difficult to obtain. On the other hand, when the
amount of oxide particles contained is more than 30 mass%, the formation of the
10 component crystal of the chemical conversion treatment covering film to be formed
may reach a maximum, and accordingly the adhesiveness between the resin coating
film and the coating treatment film may reach a maximum; and the ratios of the
electrically conductive particles and the anti-corrosive particles in the coating film
are reduced, and consequently the properties of corrosion resistance before coating
15 etc. may be insufficient.
The amount of oxide particles contained is preferably 10 to 20 mass% in
terms of further improving the adhesiveness between the resin coating film and the
coating treatment film by the anchor effect of the crystal of the chemical conversion
treatment covering film and further improving weldability.
20 [0127]
In the case where the resin coating film contains non-doped oxide particles,
the amount of non-doped oxide particles contained is preferably 1 to 10 mass%
(more preferably 2.5 to 7.5 mass%) relative to the resin coating film in terms of
improving the adhesiveness to a coating treatment film after coating and weldability.
25 [0128]
(Anti- corrosive particles)
The resin coating film preferably contains anti-corrosive particles. The
anti-corrosive particles can improve the corrosion resistance of particularly the
surface of the metal sheet adjacent to the resin coating film of the surface-treated
30 metal sheet.
The anti-corrosive particles that can be contained in the resin coating film is
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not particularly limited, but preferably contains at least one selected from the group
consisting of aluminum tripolyphosphate, Zn, Mg, AI, Ti, Zr, and Ce salts of
phosphoric acid and phosphorous acid, hydrocalumite-treated phosphoric acid
compounds (as an example, EXPERT NP-530 NS produced by Toho Ganryo Kogyo
5 Co.,Ltd., which is hydrocalumite-treated zinc phosphate), Ca ion exchange silica,
and amorphous silica with an oil absorption of I 00 to 1000 rnl/1 00 g, a specific
surface area of200 to 1000 m2/g, and an average particle diameter of2 to 30 !!ill.
[0129]
A preferred anti-corrosive particles are, among these, a phosphate-based
10 anti-corrosive particles (aluminum tripolyphosphate, a hydrocalumite-treated
phosphoric acid compound, etc.) or a silica-based anti-corrosive particles, or a
combination of both from the viewpoint of achieving the corrosion resistance of both
the flawed portion and the flat surface portion. In particular, a preferred anticorrosive
particles are at least one selected from the group consisting of aluminum
15 tripolyphosphate, a hydrocalumite-treated phosphoric acid compound, Ca exchange
silica, and amorphous silica with an oil absorption of 100 to 1 000 ml/1 00 g, a
specific surface area of200 to 1000 m2/g, and an average particle diameter of2 to 30
20
!lffi.
[0130]
In the case where the resin coating film contains doped or non -doped zinc
oxide particles, the resin coating film preferably contains, as anti-corrosive particles,
aluminum dihydrogen tripolyphosphate containing Mg. Examples of the aluminum
dihydrogen tripolyphosphate containing Mg include magnesium-treated aluminum
dihydrogen tripolyphosphate, a mixture of aluminum tripolyphosphate and
25 magnesium hydroxide, and the like. It is presumed that, by aluminum dihydrogen
tripolyphosphate containing Mg being contained in the resin coating film, zinc oxide,
Mg, and aluminum dihydrogen tripolyphosphate react together to form a composite
oxide and a composite compound of Zn-Mg and a Zn-phosphoric acid compound,
and thereby excellent corrosion resistance is provided.
30 [0131]

PCT/JP2016/060488
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A coated member according to the second embodiment includes a molded
material using the surface-treated metal sheet according to the second embodiment
mentioned above as the material, a chemical conversion treatment covering fihn
located on the coating film of the molded material, and a coating treatment film
5 located on the chemical conversion treatment covering film.
That is, the coated member according to the second embodiment has the
same configuration as the coated member according to the first embodiment except
that, in place of the surface-treated metal sheet according to the first embodiment, the
surface-treated substrate according to the second embodiment is used. Hence, a
10 description of the coated member according to the second embodiment is omitted.
[0132]
Also the method for producing the coated member according to the second
embodiment has the same construction as the method for producing the coated
member according to the first embodiment except that, in place of the surface-treated
15 metal sheet according to the second embodiment, the surface-treated substrate
according to the second embodiment is used. Hence, also a description of the
method for producing the coated member according to the second embodiment is
omitted.
[Examples]
20 [0133]
The present invention will now be described still more specifically using
Examples. However, these Examples do not limit the present invention.
[0134]

[Production of surface-treated metal sheet]
1. Preparation of metal sheet
The following four types of zinc-based plated steel sheets and an AI sheet
were prepared; each of the sheets was dipped in an aqueous solution at 40°C of 2.5
30 mass% of a water-based alkaline degreasing agent (FC-301, produced by Nihon
Parkerizing Co.,Ltd.) for 2 minutes to degrease the surface, and then water washing
PCT/JP2016/060488
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and drying were performed; thus, metal sheets for coating were obtained.
·EG: a zinc-electroplated steel sheet (sheet thickness: 0.8 mm; the amount of plating
attached: 40 g/m2
)
·ZL: a Zn-10 mass% Ni alloy-electroplated steel sheet (sheet thickness: 0.8 mm; the
5 amount of plating attached: 40 g/m2
)
·GI: a zinc-hot-dipped steel sheet (sheet thickness: 0.8 mm; the amount of plating
attached: 60 g/m2
)
·GA: an alloyed zinc-hot-dipped steel sheet (sheet thickness: 0.8 mm; 10 mass% Fe;
the amount of plating attached: 45 g/m2
)
10 ·AL: a 6000-series AI sheet (sheet thickness: 1.0 mm)
[0135]
2. Formation of underlayer treatment covering film
Next, the following two types of compositions for underlayer treatment
covering formation were prepared; each of the compositions was applied to the metal
15 sheet by bar coating so that the covering thickness might be 0.08 [.liD, and the test
piece was dried by air drying in a hot-air oven at a metal surface peak temperature of
70°C; thus, an underlayer treatment covering film was formed on the surface of the
metal sheet.
·pi: a water-based coating composition composed of a Zr compound, a silane
20 coupling agent, and silica fme particles
25
·p2: a water-based coating composition composed of a polyester resin, silica fine
particles, and a silane coupling agent
[0136]
3. Formation of resin coating film
Next, in order to form each of the resin coating films of the compositions
shown in Table 1 and Table 2, the components were mixed together so as to obtain
solid content concentrations close to those of Table 1 and Table 2, and thus a waterbased
composition for resin coating formation was prepared. The resulting waterbased
composition was applied onto the metal sheet with a bar coater in accordance
30 with Table 3 to Table 5, and was dried using an oven under conditions for keeping a
maximum peak temperature of 140°C for 8 seconds; thus, a resin coating film was
5
10
PCT/JP20 16/060488
49171
formed. The amount of the resin coating fihn attached was adjusted by the dilution
of the water-based composition and the count of the bar coater so that the total
attached amount of the solid content (nonvolatile content) in the water-based
composition might be the numerical value shown in Table 3 to Table 5.
In Table 1 and Table 2, the solid content concentration of each component is
written as the ratio (unit: mass%; the value per one surface) of the solid content
(nonvolatile content) of each component to the solid content (nonvolatile content) of
the entire water-based composition.
[0137]
Details of the components (symbols) in Table 1 and Table 2 are as follows.
[0138]
(A) Electrically conductive particles
·VC: vanadium carbide (average particle diameter: 1 to 3 j.Lm)
·ZS: zirconium disilicide particles (average particle diameter: l to 3 j.Lm)
15 ·ZN: zirconium nitride particles (average particle diameter: 1 to 3 jlm)
·TN: titanium nitride particles (average particle diameter: 1 to 3 jlm)
·FeY: ferrovanadium particles (average particle diameter: 3 to 7 jlill)
·FeSi: ferrosilicon particles (average particle diameter: 3 to 7 jlill)
·SUS: SUS particles (average particle diameter: 3 to 7 jlm)
20 [0139]
(B) Anti- corrosive particles
·PA: aluminum dihydrogen tripolyphosphate (average particle diameter: 1 to 2 j.Lm)
(K-WHITE K105, produced by Tayca Corporation)
·PAM: Mg-containing aluminum dihydrogen tripolyphosphate (average particle
25 diameter: 1 to 2j.Lm) (K-WHITE G105, produced by Tayca Corporation)
·PM: magnesium phosphate (average particle diameter: 1 to 2 jlm)
·SC: calcium ion exchange silica (average particle diameter: 1 to 2 jlm)
· Si: silica (amorphous silica with an oil absorption of 100 to 1000 ml/1 00 g, a
specific surface area of200 to 1000 m2/g, and an average particle diameter of 1 to 30
30 jlill) (Sylomask 02, produced by Fuji Silysia Chemical Ltd.)
·HP: hydrocalumite-treated zinc phosphate (EXPERT NP-530 NS, produced by Toho
50171
Ganryo Kogyo Co.,Ltd.) (average particle diameter: 1 to 2 !liD)
(C) Binder resin
PCT/JP2016/060488
·U: a urethane-based resm emulsion (Superflex (registered trademark) E-2000,
produced by DKS Co. Ltd.)
5 ·P: a polyester-based resin emulsion (Vylonal (registered trademark) MD1985,
produced by Toyobo Co., Ltd.)
[0140]
(D) Oxide particles
·MgO: magnesium oxide particles (average particle diameter: 1.0 !liD)
10 ·CaO: calcium oxide particles (average particle diameter: 1.0 11m)
·Zn01: zinc oxide particles (electrically non-conductive (non-doped); average
particle diameter: 1.0 !liD)
·Sn01: tin oxide particles (non-doped; average pmticle diameter: 1.0 11m)
·SrO: strontium oxide particles (average particle diameter: 1.0 !liD)
15 ·M1: magnesium oxide particles (average particle diameter: 0.5 !liD)
·M2: magnesium oxide particles (average particle diameter: 2.0 !liD)
·M3: magnesium oxide particles (average particle diameter: 5.0 11m)
·M4: magnesium oxide particles (average particle diameter: 10.0 !liD)
[0141]
20 For each kind of oxide particles mentioned above, the oxide particles were
dispersed in water- in which the resin had been added, and pulverization was
performed with a ball mill; and the resulting material was used. For the average
particle diameter of the oxide particles, the pulverization time was adjusted, and the
average particle diameter in the resin coating film was measured. All of the oxide
25 particles mentioned above are non-doped oxide particles.
[0142]
(E) Other additives
·Wax: polyethylene wax
·ZrO: zirconia particles (zirconia sol NanoUse ZR-30AL, produced by Nissan
30 Chemical Industries, Ltd.)
·T: titania (titanium oxide R-930, produced by Ishihara Sangyo Kaisha, Ltd.)
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·CS: colloidal silica (silica sol ST-0, produced by Nissan Chemical Industries, Ltd.)
[0143]
5. Production of surface-treated metal sheet
The underlayer treatment covering fihn and the resin coating fihn were
5 formed on the metal sheet in accordance with the description of Table 1 to Table 5
and the operating methods mentioned above; thus, a surface-treated metal sheet of
each sample number was produced.
10
[0144]
[Chemical conversion treatability evaluation test]
The surface-treated metal sheet of each sample number was press-molded.
The resulting molded material was subjected to surface conditioning at room
temperature for 20 seconds using a surface conditioning treatment agent, Prepalene
X (product name) produced by Nihon Parkerizing Co.,Ltd. Further, chemical
conversion treatment (phosphate treatment) was performed usmg a chemical
15 converswn treatment liquid (zinc phosphate treatment liquid), "Palbond 3020
(product name)" produced by Nihon Parkerizing Co.,Ltd. The molded material was
dipped in the chemical conversion treatment liquid for 120 seconds, with the
temperature of the chemical conversion treatment liquid set to 4 3 °C, and then water
washing and drying were performed.
20 [0145]
Random 5 visual fields (125 ).liil x 90 !!ill) of the surface of the molded
material after chemical conversion treatment (phosphate treatment) were observed
with a scanning electron microscope (SEM) at a magnification of 1000 times, and
back scattered electron images (BSE images) were obtained. In the back scattered
25 electron image, the observation area was displayed as an image by the gray scale.
In the back scattered electron image, the contrast is different between a portion where
a phosphate covering film that is a chemical conversion treatment covering film is
formed and a portion where a phosphate covering fihn is not formed. Thus, the
numerical range XI of the lightness (a plurality of levels of gradation) of a portion
30 where a phosphate covering fihn was not formed was determined in advance by a
SEM and an energy dispersive X-ray spectrometer (EDS).
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In the back scattered electron image of each visual field, the area A 1 of an
area showing the contrast of the numerical range X1 was found by image processing.
Then, the transparent area ratio TR (%) of each visual field was found on the basis of
the following formula.
5 ·Formula: TR = (Al/AO) x 100
10
Here, in Formula (1) above, AO represents the total area of the visual field
(11,250 11m2
). The average of the transparent area ratios TR (%) of the 5 visual
fields was defined as the transparent area ratio (%) of the steel material of the sample.
[0146]
"C" of the "Chemical conversion treatability" section in Table 3 to Table 5
means that the transparent area ratio was 15% or more. "B" means that the
transparent area ratio was not less than 5% and less than 15%. "A" means that the
transparent area ratio was less than 5%. The case of "B" or "A" in the transparency
evaluation was assessed as excellent in chemical conversion treatability (phosphate
15 treatability).
[0147]
[Eleetrodeposition coating treatment film adhesiveness evaluation test]
After the chemieal conversion treatment (phosphate treatment) mentioned
above was performed, the surface-treated metal sheet was coated with a cationic
20 electrodeposition coating material produced by Nippon Paint Co., Ltd. by
electrodeposition with slope energization at a voltage of 160 V, and baking coating
was performed at a baking temperature of 170°C for 20 minutes. The average of
film thicknesses of the coating treatment film after electrodeposition coating was 10
11m in all the samples.
25 After the electrodeposition coating was performed, 100 one-millimeter grid
squares were provided to the coating treatment film of the surface-treated metal sheet
with a cutter (load: 500 gf; 1 gf being approximately 9.8 x 10·3 N), and a polyester
tape was adhered to the grid squares. After that, the tape was ripped off. The
number of grid squares peeled off by the ripping-off of the tape was found, and the
30 rate of peeling of the coating treatment film (%) was found on the basis of the
following formula.
PC'l'/JP2016/060488
53171
·Formula: Rate of peeling of the coating treatment film= (the number of grid squares
peeled off!! 00) x 100
[0148]
"D" of the "Electrodeposition coating treatment film adhesiveness" section
5 in Table 3 to Table 5 means that the rate of peeling of the coating treatment film was
10.0% or more. "C" means that it was not less than 5.0% and less than 10.0%.
"B" means that the rate of peeling of the coating treatment film was not less than
1.0% and less than 5.0%. "A" means that the rate of peeling of the coating
treatment film was less than 1.0%. The case of "B" or "A" in the electrodeposition
10 coating treatment film adhesiveness evaluation was assessed as excellent in
electrodeposition coating treatment film adhesiveness.
[0149]
[SDT resistance evaluation test]
After the electrodeposition coating mentioned above, the surface-treated
15 metal sheet was dipped in a 5% NaCI aqueous solution having a temperature of 50°C
for 500 hours. After the dipping, a polyester tape was adhered to the whole of an
area of 60 mm x 120 mm (area AlO = 60 mm x 120 mm = 7200 mm2
) of the test
surface. After that, the tape was ripped off. The area A2 (mm2
) of the coating
treatment film peeled off by the ripping-off of the tape was found, and the rate of
20 peeling of the coating treatment film (%) was found on the basis of the following
formula.
·Formula: Rate of peeling of the coating treatment film= (A2/A10) x 100
[0150]
"D" of the "SDT resistance" section in Table 3 to Table 5 means that the rate
25 of peeling of the coating treatment film was 30.0% or more. "C" means that it was
not less than 10.0% and less than 30.0%. "B" means that the rate of peeling of the
coating treatment film was not less than 5.0% and less than 10.0%. "A" means that
the rate of peeling of the coating treatment film was less than 5.0%. The case of
"B" or "A" in the SDT resistance evaluation was assessed as excellent in SDT
30 resistance.
[0151]
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[Weldability test]
The surface-treated metal sheet before performing the chemical conversion
treatment (phosphate treatment) mentioned above was subjected to a consecutive
spot weldability test, using CF type Cr-Cu electrodes having a tip with a diameter of
5 5 mm and a curvature radius of 40 mm, at an applied pressure of 1.96 kN, a welding
current of 8 kA, and an energization time of 12 cycles/50Hz; and the number of
welds at the time immediately before the nugget diameter became less than 3,[ t (t
being the sheet thickness) was found. The superiority or inferiority of spot
weldability was evaluated using the following evaluation points.
10 A: the number of welds was 1000 or more
B: not less than 200 and less than 1000
C: less than 200
D: no nugget was generated and no spot was able to be welded
The case of "B" or "A" in the weldability test was assessed as excellent in
15 weldability.
[0152]
[Cycle corrosion property (corrosion resistance) test]
After the electrodeposition coating mentioned above was performed, a gap
was provided to the coating treatment film of the surfuce-treated metal sheet with a
20 cutter (load: 500 gf; 1 gf being approximately 9. 8 x 10'3 N), and a cycle corrosion
test of the following cycle conditions was 11erformed 180 cycles.
[0153]
-Cycle conditions-
A cycle corrosion test was performed in which a procedure of 2 hr of salt
25 water spraying (SST; 5% NaCl; atmosphere: 35°C ), 2 hr of drying (60°C), and 4 hr
of wetting (50°C; RH: 98%) was taken as 1 cycle.
30
After that, the presence or absence of a blister of the coating film occurring
in an area of approximately 1 em width from the cut portion was observed.
[0154]
"E" of the "Cycle corrosion property (corrosion resistance) test" section in
Table 3 to Table 5 means that a coating blister of more than 3 mm occurred. "D"
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55171
means that a coating blister of not less than 1.5 mm and less than 3 mm occurred.
"C" means that a coating blister of not less than 1 mm and less than 1.5 mm occurred.
"B" means that a minute coating blister of less than 1 mm occurred. "A" means that
no coating blister occurred. The case of "C," "B," or "A" in the cycle corrosion
5 property (corrosion resistance) test was assessed as excellent in cycle corrosion
property (corrosion resistance).
[0155]
[Powder coating treatment film adhesiveness evaluation test]
After the chemical conversion treatment (phosphate treatment) mentioned
10 above was performed, the surface-treated metal sheet was electrostatically coated
with a polyester-based resin coating material (a powder polyester coating material
"Powdax," produced by Nippon Paint Co., Ltd.), and baking coating was performed
at a baking temperature of l80°C for 20 minutes. The average of film thicknesses
of the coating treatment film after powder coating was 50 J.Lm in all the samples.
15 After the powder coating, the surface-treated metal sheet was dipped in a
5% NaCl aqueous solution having a temperature of 50°C for 500 hours. After the
dipping, a polyester tape was adhered to the whole of an area of 60 mm x 120 mm
(area AIO = 60 mm x 120 mm = 7200 mm2
) of the test surface. After that, the tape
was ripped off. The area A2 (mm2
) of the coating treatment film peeled off by the
20 ripping-off of the tape was found, and the rate of peeling of the coating treatment
film(%) was found on the basis ofthe following formula.
·Formula: Rate of peeling of the coating treatment film= (A2/AIO) x 100
The powder coating treatment film adhesiveness evaluation test was
performed on sample Nos. I to 3 of the surface-treated metal sheet.
25 [0156]
"D" of the "Powder coating treatment film adhesiveness" section in Table 3
to Table 5 means that the rate of peeling of the coating treatment film was 30.0% or
more. "C" means that it was not less than 10.0% and less than 30%. "B" means
that the rate of peeling of the coating treatment film was not less than 5.0% and less
30 than 10.0%. "A" means that the rate of peeling of the coating treatment film was
less than 5.0%. The case of "B" or "A" in the powder coating treatment film