U.S. patent number RE36,911 [Application Number 09/140,471] was granted by the patent office on 2000-10-17 for aluminum flake pigment.
This patent grant is currently assigned to Toyo Aluminium Kabushiki Kaisha. Invention is credited to Takao Hieda.
United States Patent |
RE36,911 |
Hieda |
October 17, 2000 |
Aluminum flake pigment
Abstract
An aluminium flake pigment characterized in that the ratio of
the average thickness of flakes to the average diameter of flakes
is in the range of 0.025 to 0.3, preferably 0.028 to 0.1 and the
ratio of the water covering area to the specific surface area is in
the range of 0.18 to 0.4, preferably 0.19 to 0.35 is disclosed
herein. The aluminium flake pigment of the invention has the
improved resistance to the circulation of the metallic paint during
the painting.
Inventors: |
Hieda; Takao (Nara,
JP) |
Assignee: |
Toyo Aluminium Kabushiki Kaisha
(Tokyo, JP)
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Family
ID: |
16593902 |
Appl.
No.: |
09/140,471 |
Filed: |
August 25, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
234723 |
Aug 22, 1988 |
04936913 |
Jun 26, 1990 |
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Foreign Application Priority Data
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Aug 25, 1987 [JP] |
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62-210715 |
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Current U.S.
Class: |
106/404;
427/427.5; 428/457; 428/546; 75/954 |
Current CPC
Class: |
B82Y
30/00 (20130101); C08K 3/08 (20130101); C09C
1/64 (20130101); C09C 1/646 (20130101); C09D
5/38 (20130101); C01P 2004/03 (20130101); C01P
2004/20 (20130101); C01P 2004/54 (20130101); C01P
2004/62 (20130101); C01P 2004/64 (20130101); C01P
2006/12 (20130101); C01P 2006/60 (20130101); C01P
2006/80 (20130101); Y10S 75/954 (20130101); Y10T
428/31678 (20150401); Y10T 428/12014 (20150115) |
Current International
Class: |
C08K
3/00 (20060101); C08K 3/08 (20060101); C09C
1/62 (20060101); C09C 1/64 (20060101); C09D
5/38 (20060101); C09C 001/64 () |
Field of
Search: |
;106/404 ;75/954
;428/546,457 ;427/421 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 098 108 |
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Jan 1984 |
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EP |
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0 122 763 |
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Oct 1984 |
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EP |
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49-14358 |
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Feb 1974 |
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JP |
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706251 |
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Jan 1951 |
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GB |
|
706251 |
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Feb 1954 |
|
GB |
|
1337858 |
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May 1971 |
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GB |
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1520127 |
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Sep 1975 |
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GB |
|
Other References
Chemical Abstracts, vol. 81, No. 14, Oct. 7, 1984, p. 94, Abstract
No. 79479s. .
Chemical Abstracts, vol. 81, No. 14, Oct. 7, 1974, p. 94, No.
79479s, Columbus Ohio, US. .
Communication dated Dec. 27, 1988 re EPA No. 88307829.7, Toyo
Aluminium Kabushiki Kaisha, 3 pages..
|
Primary Examiner: Green; Anthony
Attorney, Agent or Firm: Dike, Bronstein, Roberts &
Cushman, LLP Conlin; David G. Daley, Jr.; William J.
Claims
I claim:
1. An aluminum flake pigment wherein the ratio of the average
thickness of flakes to the average diameter of flakes is in the
range of 0.025 to 0.3 and the ratio of the water covering area to
the specific surface area is in the range of 0.18 to 0.4.
2. The pigment as claimed in claim 1 wherein the ratio of the
average thickness of flakes to the average diameter of flakes is in
the range of 0.028 to 0.1.
3. The pigment as claimed in claim 1, wherein the ratio of the
water covering area to the specific surface area is in the range of
0.19 to 0.35. .Iadd.
4. An aluminum flake pigment, wherein the ratio of the average
thickness of flakes to the average diameter of flakes is in the
range of 0.025 to 0.3 and the ratio of the water covering area to
the specific surface area is in the range of 0.18 to 0.4, wherein
the flakes have a sufficiently uniform thickness to orient the
flakes regularly in a painted sheet..Iaddend..Iadd.5. An aluminum
flake pigment, wherein the ratio of the average thickness of flakes
to the average diameter of flakes is in the range of 0.025 to 0.3
and the ratio of the water covering area to the specific surface
area is in the range of 0.18 to 0.4, which flakes orient regularly
in a painted sheet..Iaddend..Iadd.6. An aluminum flake pigment,
wherein the ratio of the average thickness of flakes to the average
diameter of flakes is in the range of 0.025 to 0.3 and the ratio of
the water covering area to the specific surface area is in the
range of 0.18 to 0.4, the flakes having a uniform thickness and
shape which essentially eliminates bent or ruptured flakes caused
by paint circulation..Iaddend..Iadd.7. The aluminum flake pigment
of claim 4, 5 or 6, wherein after paint circulation the flakes
retain at least 93% brightness..Iaddend..Iadd.8. The pigment of
claim 7, wherein the retained
brightness is between about 93% and 99%..Iaddend..Iadd.9. The
aluminum flake pigment of claim 1, wherein the flakes orient
regularly, as observed by scanning electron microscope, when
applied in a paint film made in the following manner:
(a) 34.3 parts by weight of the aluminum flake pigment are mixed
with 160.0 parts by weight of acrylic resin containing 50.0% by
weight of dry matter and 33.3 parts by weight of melamine resin
containing 60% by weight of dry matter, to form a paint;
(b) viscosity of the paint is adjusted to 20 to 21 seconds on Ford
cup #4, with a mixed solvent of ethyl acetate, butyl acetate,
xylene, aromatic solvent having a typical flashpoint of 49 degrees
C. and CH.sub.2 COOCH.sub.2 CH.sub.2 OOC.sub.2 H.sub.5 (mixed ratio
by volume=30:10:30:20:10);
(c) 300 g of the viscosity-adjusted paint is charged into a vessel
provided with a jacket for circulating cooling water and stirred by
a stirrer with turbine blades for 1 hour;
(d) the paint is sprayed on polished mild steel sheet to form a
paint film having a thickness of about 20 .mu.m; and
(e) the paint film is baked at 140.degree. C. for 30
minutes..Iaddend.
Description
FIELD OF THE INVENTION
The invention relates to an aluminium flake pigment suitable for
incorporating a metallic paint. More particularly, it relates to
the aluminium flake pigment having the improved resistance to the
circulation of the metallic paint during the painting.
BACKGROUND OF THE INVENTION
When the paint incorporating the aluminium flake pigment is applied
to any article such as car, the paint is necessarily subjected to
the circulation by any of the pumps for preventing the
sedimentation of the pigment in the tank. However, the vigorous
turbulent flow is caused near the pump due to the circulation and
therefore the aluminium flakes are subjected to the excess impact
so as to cause the collisions between the flakes and between the
flakes and the inner wall of tank, thereby the aluminium flakes
being bent and/or ruptured.
If the paint containing the bent flakes is employed, the resultant
paint film will have the poor metallic brightness because the
flakes in the paint film are oriented irregularly. And, if the
paint containing the ruptured flakes is employed, the dark paint
film will be formed because there are a great deal of the torn
pieces of the ruptured flakes.
Accordingly, the aluminium flake pigment having the improved
resistance to the circulation is requested.
SUMMARY OF THE INVENTION
The invention provides the aluminium flake pigment which is
characterized in that the ratio of the average thickness of flakes
(d; .mu.m) to the average diameter of flakes (D.sub.50 ; .mu.m) is
in the range of 0.025 to 0.3 and the ratio of the water covering
area (WCA; m.sup.2 /g) to the specific surface area (SSA; m.sup.2
/g) is in the range of 0.18 to 0.4.
The aluminium flake pigment of the invention each ratio of which is
in the above range has the improved resistance to the circulation
together with the excellent brightness and the high mechanical
strength.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is the scanning electron microscopic photograph (.times.600)
showing the cross section of the painted sheet prepared with the
paint in which the aluminium flake pigment of Example 1 is
incorporated after circulation.
FIG. 2 is the scanning electron microscopic photograph (.times.600)
showing the cross section of the painted sheet prepared with the
paint in which the aluminium flake pigment of Comparative Example 1
is incorporated after circulation.
FIG. 3 is the scanning electron microscopic photograph
(.times.1000) showing the cross section of the painted sheet
prepared with the paint in which the aluminium flake pigment of
Example 5 is incorporated after the circulation.
FIG. 4 is the scanning electron microscopic photograph
(.times.1000) showing the cross section of the painted sheet
prepared with the paint in which the aluminium flake pigment of
Comparative Example 4 is incorporated after the circulation.
DETAILED DESCRIPTION OF THE INVENTION
The average thickness of flakes (d), the average diameter of flakes
D.sub.50), the water covering area (WCA) and the specific surface
area (SSA) herein are defined as follows:
The average thickness of flakes (d, .mu.m) is the value obtained by
measuring the water covering area (WCA) per g of the metal content
and then calculating according to the following equation.
Please refer to J. D. Edwards and R. I. Wray, Aluminium Paint and
Powder (3rd Ed.), pp. 16 to 22, Reinhold Publishing Corp., New
York(1955).
The average diameter of flakes (D.sub.50, .mu.m) is the value
obtained by measuring with a Microtrac particle-size analyzer.
The water covering area (WCA; m.sup.2 /g) is the value obtained by
measuring according to the method described in J. D. Edwards and R.
I. Wray, Aluminium Paint and Powder (3rd Ed.), pp. 16 to 22,
Reinhold Publishing Corp., New York(1955).
The specific surface area (SSA; m.sup.2 /g) is the value obtained
by calculating the nitrogen gas volume adsorbed on the flake
surface per g of flakes according to BET method.
In the invention, the aluminium flake pigment should have the ratio
of the average thickness of flakes (d) to the average diameter of
flakes (D.sub.50) in the range of 0.025 to 0.3. When the flakes
have the ratio d/D.sub.50 of less than 0.025, the flakes will be
easily bent and/or ruptured due to the circulation because they are
very thin. The higher the ratio d/D.sub.50 is, the lower the
percentages of the flakes which are bent and/or ruptured due to the
circulation are. When the flakes has the ratio d/D.sub.50 of above
0.3, however, the flakes in the paint film are not regularly and in
parallel oriented because each flake can move freely although the
flakes have the high resistance to the circulation, thereby the
resultant paint film will have the poor metallic brightness.
Preferably, the aluminium flake pigment in the invention has the
ratio d/D.sub.50 in the range of 0.028 to 0.1.
Further, the aluminium flake pigment in the invention should have
the ratio of the water covering area (WCA; m.sup.2 /g) to the
specific surface area (SSA; m.sup.2 /g) in the range of 0.18 to
0.4. As the observation of the flakes having the ratio WCA/SSA in
the above range under the scanning electron microscope, it was
found that most of the flakes have the rounded
profiles and the uniform thickness throughout them and the finely
divided powder or fragments are hardly attached on the flakes. The
flakes of such a form are supposed to have higher resistance to
circulation. While, according to the observation of the flakes
having the ratio WCA/SSA of less than 0.18 under the scanning
electron microscope, the flakes whose ends are very thinned such as
the flakes having the corrugated profiles, the partially cracked
and/or broken flakes and the flakes having the finely divided
powder and/or broken fragments on their surfaces were observed,
which are supposed to lack in the resistance to the circulation.
The higher the ratio WCA/SSA is, the lower the percentages of the
flakes which are bent and/or ruptured due to the circulation are.
When the flakes have the ratio WCA/SSA of above 0.4, however, it is
not suitable since the productivity of the aluminium flake pigment
is unsatisfactory although the flakes have the high resistance to
the circulation.
Preferably, the aluminium flake pigment in the invention has the
ratio WCA/SSA in the range of 0.19 to 0.35.
The aluminium pigment of the invention can be particularly suitable
for incorporating in paint. The aluminium pigment is mixed with any
vehicle, any resin and other conventional additives to prepare the
water or oily paint. Of course, other pigment(s) may be also
incorporated in paint.
Further, the aluminium pigment of the invention can be incorporated
in inks, adhesives, the resins and the like.
The aluminium flake pigment of the invention is prepared according
to any of the known processes for preparing the metal powder
pigment.
The aluminium powder used as the starting material is selected
among the commercially available aluminium powder according to the
intended tint. If the higher brightness is intended, extracoarse
aluminium powder is selected. If the lower brightness, on the other
hand, fine aluminium powder is selected. The commercially available
aluminium powder can be classified according to roughness into four
groups (extracoarse, coarse, medium and fine). The extracoarse
aluminium powder has the larger average thickness (d) and average
diameter (D.sub.50)as well as the smaller water covering area (WCA)
and specific surface area (SSA). Conversely, the fine aluminium
powder has the smaller average thickness (d) and average diameter
D.sub.50) as well as the larger water covering area (WCA) and
specific surface area (SSA).
The aluminium powder is milled according to a dry or wet milling
process. Preferably, the aluminium powder is ground together with
the grinding medium such as mineral spirit and if necessary other
grinding additives in suitable mill such as ball mill, hammer mill,
rod mill and the like under carefully controlled grinding
conditions until the desired aluminium flakes are obtained. The
rotation speed of mill and the grinding time are varied depending
on the desired characteristics of flakes. Generally, the rotation
speed of mill is selected in the range of 5 to 44 rpm and the
grinding time is selected in the range of 1.5 to 15 hours. The
temperature and pressure are not particularly limited.
If desired, the aluminium flake may be subjected to the standard
leafing treatment.
EXAMPLES
The invention will now be further described by the following,
non-limiting examples.
Example 1
Into the ball mill (inner diameter=500 mm, length=180 mm)
containing 50 kg of steel balls each of which has a diameter of 2
mm, the formulation consisting of 1.0 kg of atomized aluminium
spherical or spheroidal powder (Alcan MDX-81, ex Alcan Aluminium
Ltd.), 5.0 (of mineral spirit and 500 g of oleic acid was charged.
Then, the charge in the mill was ground by operating the mill at 38
rpm (corresponding to 64% of the critical rotation speed) for 3.5
hours.
After the grinding, the slurry in the mill was washed out with
mineral spirit and subjected to the vibrating screens of 150, 350
and 400 mesh, successively. The liquid part of the passed-through
slurry was removed through the pan filter. The resultant cake
(NV=85%) was transferred into the kneader and kneaded for 1 hour so
as to obtain the aluminium flake pigment (NV=80%).
Next, a paint was prepared from 34.3 parts by weight of aluminium
flake pigment, 160.0 parts by weight of ALMATEX 100 (acrylic resin
containing 50.0% by weight of dry matter, ex MITSUI TOATSU
CHEMICALS, INC.) and 33.3 parts by weight of UVAN 20SE-60 (melamine
resin containing 60% by weight of dry matter, ex MITSUI TOATSU
CHEMICALS, INC.). The viscosity of the paint was adjusted with a
mixed solvent of ethyl acetate, butyl acetate, xylene, Solvesso #
100 and Cellosolve acetate (mixed ratio by volume=30:10:30:20:10)
so as to be 20 to 21 seconds on Ford cup # 4.
A portion of the above paint was subjected to a circulation
(simulation test). That is, 300 g of the above paint was charged
into a vessel provided with a jacket for circulating the cooling
water and stirred by a stirrer with turbine blades for 1 hour.
The painted sheet was prepared employing the paint with or without
subjecting to circulation as follows.
The paint was sprayed on polished mild steel sheet by automatic
spraying machine so that the resultant paint film has a thickness
of about 20 .mu.m. Then, a clear coat was formed on this paint film
according to procedures wet-on-wet coating followed by baking at
140.degree. C. for 30 minutes.
The procedure of example 1 was repeated except that the grinding
time was 1 hour.
Example 3
The procedure of example 1 was repeated except that as the atomized
aluminium powder AB-5003 (ex TOYO ALUMINIUM K. K.) was used and the
grinding time was 2.5 hours.
And, 19.1 parts by weight of aluminium flake pigment was used in
the preparation of the paint.
Example 4
The procedure of example 1 was repeated except that as the atomized
aluminium powder Alcan MDX-65 (ex Alcan Aluminium Ltd.) was used
and the grinding time was 2.5 hours.
Example 5
The procedure of example 1 was repeated except that as the fine
portion atomized aluminium powder Alcan MDX-65 (ex Alcan Aluminium
Ltd.) was used and the grinding time was 5.5 hours.
And, 14.3 parts by weight of aluminium flake pigment was used in
preparation of the paint.
Example 6
The procedure of example 1 was repeated except that as the atomized
aluminium powder an equal mixed powder of fine portion of Alcan
MDX-65 (ex Alcan Aluminium Ltd.) and AC-5005 (ex. TOYO ALUMINIUM
K.K.) was used and the grinding time was 8 hours.
And, 9.5 parts by weight of aluminium flake pigment was used in the
preparation of the paint.
Comparative Example 1
The extracoarse aluminium powder described in Japanese Pat.
Application Laying-Open (KOKAI) No. 49-14358 was used, which is
said to have the highest quality.
Comparative Example 2
The commercially available extracoarse aluminium powder (ex TOYO
ALUMINIUM K.K.) was used.
Comparative Example 3
The commercially available coarse aluminium powder (ex TOYO
ALUMINIUM K.K.) was used.
Comparative Example 4
The commercially available medium aluminium powder (ex TOYO
ALUMINIUM K.K.) was used.
Comparative Example 5
The commercially available fine aluminium powder (ex TOYO ALUMINIUM
K.K.) was used.
Test Example 1
The aluminium flake pigment (NV=80%) obtained in each Example and
Comparative Example was subjected to the following tests.
test 1water covering area (WCA)
The aluminium flake pigment was subjected to a leafing treatment by
adding 1 g of stearic acid to 1 g of aluminium flake pigment and
then heating with a small volume of xylene. The leafing flakes were
dry-powdered with acetone to prepare the sample.
The water covering area of the thus-prepared sample was measured
according to the method described in J. D. Edwards and R. I. Wray,
Aluminium Paint and Powder (3rd Ed.), pp. 16 to 22, Reinhold
Publishing Corp., New York(1955).
test 2average thickness (d)
The average thickness of the above sample was calculated according
to the above-mentioned equation based on the WCA value obtained in
test 1.
test 3average diameter D.sub.50)
The average diameter of the above sample was determined with a
Microtrac particle-size analyzer
test 4specific surface area (SSA)
The aluminium flake pigment was washed with a mixed solvent of
ether and acetone and then dry-powdered with acetone to prepare the
sample
The specific surface area of the thus-prepared sample was
calculated from the adsorbed nitrogen gas volume according to the
BET method.
The test results are shown in Table 1.
TABLE 1 ______________________________________ WCA d D.sub.50
d/D.sub.50 SSA WCA/SSA (m.sup.2 /g) (.mu.m) (.mu.m) (-) (m.sup.2
/g) (-) ______________________________________ Example 1 0.15 2.7
34.9 0.077 0.80 0.188 Example 2 0.10 4.00 16.0 0.250 0.56 0.180
Comp. 0.36 0.89 29.8 0.030 2.25 0.160 Example 1 Comp. 0.50 0.80
31.4 0.025 2.90 0.172 Example 2 Example 3 0.50 0.80 15.5 0.052 1.45
0.345 Example 4 0.80 0.50 15.9 0.031 3.35 0.239 Comp. 0.90 0.44
23.9 0.019 3.92 0.230 Example 3 Example 5 1.20 0.33 11.2 0.029 3.90
0.308 Comp. 1.33 0.30 17.6 0.017 4.48 0.297 Example 4 Example 6
1.70 0.24 8.5 0.028 5.49 0.310 Comp. 1.60 0.25 14.0 0.018 6.20
0.258 Example 5 ______________________________________
Test Example 2
The painted sheet prepared in each Example and Comparative Example
was subjected to the following tests.
test 5brightness
The brightness of the painted sheet prepared with the paint before
circulation was compared with that of the painted sheet prepared
with the paint after circulation.
The brightness was measured according to the method described in
Japanese Pat. Application Laying-Open (KOKAI) No.60-3016 by the
TM-type goniophotometer (ex MURAKAMI COLOR RESEARCH LABORATORY),
provided that the incidence angle was set at 45.degree. and the
oblique angle of the painted sheet was set at 5.degree..
test 6number of bent flakes
The painted sheets prepared with the paint before and after the
circulation were observed under the scanning electron microscope so
as to count the number of the bent flakes per 100 flakes in the
paint film.
The test results are shown in Table
TABLE 2 ______________________________________ brightness number of
bent flakes circulation retention circulation before after (%)
before after ______________________________________ Example 1 190
180 95 0/100 0/100 Example 2 160 155 97 0/100 0/100 Comp. Example 1
170 94 55 2/100 23/100 Comp. Example 2 157 80 51 4/100 30/100
Example 3 186 184 99 0/100 2/100 Example 4 179 166 93 0/100 5/100
Comp. Example 3 156 126 81 2/100 17/100 Example 5 153 152 99 0/100
2/100 Comp. Example 4 153 103 67 2/100 10/100 Example 6 98 96 98
0/100 2/100 Comp. Example 5 95 83 87 8/100 *
______________________________________ *not determined because
there were many bent and/or ruptured flakes.
The scanning electron microscopic photographs showing the cross
sections of the painted sheets prepared with the paint after the
circulation are shown in FIG. 1 to 4. FIG. 1 and FIG. 2 show the
painted sheets in Example 1 and Comparative Example 1, respectively
(.times.600). FIG. 3 and FIG. 4 show the printed sheet in Example 5
and Comparative Example 4 respectively (.times.1000).
EFFECT OF THE INVENTION
The aluminium flake pigment of the invention can retain the
original brightness after subjecting to the circulation.
The bent and/or ruptured flakes are not substantially found in the
paint film prepared with the paint incorporating the aluminium
flake pigment of the invention.
The above effects are clear from the scanning electron microscopic
photographs shown in Figures. Please note that the aluminium flakes
are oriented regularly in the painted sheets shown in FIG. 1 and
FIG. 3, while the aluminium flakes are oriented irregularly in the
painted sheets shown in FIG. 2 and FIG. 4.
Accordingly, the aluminium flake pigment of the invention can be
said to be very excellent in the resistance to the circulation.
* * * * *