Note: Descriptions are shown in the official language in which they were submitted.
7;;~01
ALUMINIUM PIGMENT COMPOSITION
Field of the Invention-
The invention relates to an aluminium pigment
composition. More particularly, the invention relates to the
aluminium pigment composition suitable for incorporating in
a water base paint such as a water-soluble paint, an aqueous
emulsion paint and the like.
Background of the Invention-
Recently, water base paints have been extensively
developed in many countries including Japan as the
replacement of the organic solvent base paints for saving
costs and resolving the environmental pollution problemsO In
this connection, the development of metallic pigments
suitable for incorporating in the water base paints has been
highly desired to use for top coating the automobiles and
the other vehicles so as to give them -the high grade
appearances.
As the metallic pigment for incorporating in ~he
water base paint, a pigment composition comprising aluminium
flakes and a surfactant which is~ added for improving the
water~dispersibility has been known. However, this
composition has the important defect of evolving a large
volume o~ hydrogen gas during a long storage period, thereby
an explosion may occur.
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As the method for resolving the above-mentioned
defect, the methods of forming anti-corrosive coatings on
the aluminium flakes by adding an anti-corrosive material
such as morpholine, dimeric acid, organic phosphate ester,
boric acid salt and the like in addition to the surfactant
have been proposed. However, these methods could not
~- completely prevent the evolution of hydrogen gas. Further,
the coatings formed on the aluminium flakes caused another
defects of darkening the color tone characteristic of the
metallic pigment as well as aggregating the flakes during
~ the long storage period~
- A method of contacting aluminium flakes with an
aqueous solution containing available phosphate ions
supplied from the phosphate compound such as (NH4)2HPO4 and
the like in an amount of at least 0.7 % by weight based on
the aluminium weight and having pH of about 1.5 to 11 is
disclosed in USP 2,858,230. A pigment composition obtained
by the above-mentioned method can prevent considerably the
evolution of hydrogen gas in the aqueous medium, but this
composition cannot give the paint film with the satisfactory
color tone. And, this composition tends to gradually darken
the color tone with the evolution of the gas and to
~aggregate the flaXes during the storage.
An object of the~invention is to provide~a pigment
compositlon whlch can be incGrporated in the water base
paint without showing the above-mentioned defects.
:
An object of the lnvention is to provide an aluminium
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flake ~igment composition which when incorporated in the
water base paint, evolves a little volume of hydrogen gas
and has a little tendency of darkening the color tone and
aggregating the flakes during the long storage period.
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The above-mentioned objects of the invention ~an be
achieved by the pigment composition according to the
invention which comprises aluminium flakes, a phosphorus
supplied from an inorganic phosphoric acid in an amount of
500 to 10,000 ppm based on the aluminium weight, an
aliphatic compound having at least one functional group
within a molecule in an amount of 0~3 to 5 parts by weight
per 100 parts by weight of aluminium, water in an amount of
0.05 to 10 parts by weight per 100 parts by weight of
aluminium, a water-compatible alcohol in an amount of 5 to
100 parts by weight per 100 parts by weight of aluminium and
a hydrocarbon oil in an amount of 1 to 70 parts by weight of
100 parts by weight of aluminium.
Detailed Description of the Invention:
The aluminium flakes usable in the invention are not
particularly limited, but the aluminium flakes having
surface properties, size and form suitable as the metallic
flake pigment are preferable. Generally, the aluminium
.
flakes obtained by the so-called Hall process wh~rein the
aluminium powder is subjected to grinding in a hydrocarbon
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oil in the presence-of a grinding agent in a ball mill are
used.
The aluminium flakes in the pigment composition
according to the invention have the thin and dense coatings
containing phosphor supplied from the inorganic phosphoric
acid. The inorganic phosphoric acid usable in the invention
may be at least one member selected from the group
consisting of ortho-phosphoric acid, pyro-phosphoric acid,
triphosphoric ~cid, tetraphosphoric acid and phosphorous
acid.
The phosphor content in the coating should be 500 to
10,000 ppm based on the aluminium weight~ Preferably, the
phosphor content is 1,000 to 7,000 ppm based on the
aluminium weight. If the phosphorus content is less than 500
ppm the larger volume o hydrogen gas evolves, while if it
is over 10,000 ppm the flakes may aggregate and the color
tone may darken.
The aliphatic compound is used in the invention for
preventing the aggregation of the flakes by adsorbing or
binding it on the coating. Therefore, the aliphatic compound
used in the invention should have at least one functional
group within the molecule. The preferable functional group
may be selected from the group consisting of:
-OH;
-COOR wherein R is a lower ( for example C1 - C5
alkyl group;
-COOM wherein M is an alkaline metal;
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COO ~ Me wherein Me is an alkali earth metal;
- COO
-CONH2;
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-CO
~NH2;
~NH;
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-O - P - OH;
I
OH
O
_O >1I d
-O
O
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~O - S - OH.
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'-Further, it is preferable that the aliphatic compound has 8
to 40 carbon atoms. If the compound having 7 or less carbon
atoms is used, the aggregation of the flakes may not be
prevented as desired since the carbon chains in the pendant
residues adsorbed or bound to the coating are too short.
While, the compound having 41 or more carbon atoms is used,
the~handling is difficult since its molecular weight is too
high. More preferably, the aliphatic compound having at
least one of -NH2 or >NH is used in the invention. The
typical~examples of such aliphatic amines may include
2-ethylhexylamine, caprylamine, decylamine, laurylamine,
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myristylamine, palmitylamine, stearylamine, ole~llamine,
eicosylamine, di-2-ethylhexylamine, dicaprylamine,
didecylamine, dilaurylamine, dimyristylamine, dipalmityl-
amine, distearylamine, dioleylamine, dieicosylamine and the
like. The examples of the other aliphatic compound usable in
the invention may include an aliphatic higher alcohol such
as lauryl alcohol and stearyl alcohol; an ester of aliphatic
acid with lower alcohol such as methyl oleate and butyl
stearate; a metal salt ( Na, K, Mg, Ca or Zn salt ) of
aliphatic acid; an aliphatic acid amide such as oleic amide,
stearic amide and dilauric amide; a mono- or diester of
aliphatic alcohol with orthophosphoric acid such as mono- or
dilauryl acid phosphate and mono- or distearylacid
phosphate.
The content of the aliphatic compound in the pigment
composition according to the invention should be 0.3 to 5
parts by weight per 100 parts by weight of aluminium.
Preferably, the content of the aliphatic compound is 1 to 4
parts by weight per 100 parts by weight of aluminium. If the
content is less than 0.3 part by weight it is difficult to
prevent the aggregation of the flakes, while if it is over 5
parts by weight the color tone and the strength of the paint
film may be adversely effected.
Water, the water-compatible alcohol and the
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hydrocarbon oil are essential in the invention for forming
the thin and dense coating. The content of water in the
~ pigment composition according to the invention should be
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0.05 to 10 parts by weight per 100 parts by weight of
aluminium. Preferably, the content of water is 0.1 to 5
parts by weight per 100 parts by weight of aluminium. If the
content of water is out of the above range, the desired
coatings cannot be formed on the flakes, whererby the
evolution of hydrogen gas cannot be completely prevented as
well as the problems of the aggregation and the change in
color tone cannot be resolved.
The alcohol used in the invention should be
compatible with water and hydrocarbon 3il in a suitable
ratio and completely dissolve the inorganic phosphoric acid~
The typical examples of the water-compatible alcohol may
include ethanol, propanol, isopropanol, butanol, isobutanol,
amylalcohol, isoamylalcohol, ethyl cellosolve, butyl
cellosolve, polyoxyethylene glycol, polyoxypropylene glycol
and a mixture thereof.
; The content of the water-compatible alcohol in the
pigment composition according to the invention should be 5
to 100 parts by weight per 100 parts by weight of aluminium.
Preferably, the content of alcohol is 20 to 40 parts by
weight per 100 par-ts by weight of aluminium. If the content
is less than 5 parts by weight the desired coating cannot be
formed, while if it is over 100 parts the pigment
composition would be unstable.
As the hydrocarbon oil, the aliphatic or aromatic
hydrocarbon oil such as mineral spirit, solvent naphtha,
HAWS, LAWS and the like which are used in the grinding of
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the aluminium powder for obtaining the aluminium flakes can
be used in the invention as it is.
The content of the hydrocarbon oil should be 1 to 70
parts by weight per 100 parts by weight of aluminium.
Preferably, the content of the hydrocarbon oil is 30 to 50
parts by weight per 100 parts by weight of aluminium. If the
content is less than 1 part by weight the pigment would be
unstable, while if it is over 70 parts by weight the coating
is formed very slowly.
The pigment composition according to the invention is
desirable to include the surfactant for improving the water
dispersibility of the aluminium flakes in the water base
paint, depending on the kind of the paint. Among the known
surfactant, the nonionic surfactant is preferable, such as
polyoxyethylene alkylphenol ether, polyoxyethylene alkyl
ether, polyethylene glycol fatty acid ester, sorbitan fatty
acid ester and polyoxyethylene sorbitan fatty acid ester.
i~ The effective content of the surfactant is about 5 to 20
parts by weight per 100 parts by weight of aluminium. It is
noted that the inclusion of the surfactant may be
unnecessary depending on the kind oE the water base paint.
The pigment composition according to the invention
may include other known additives such as levelling agent,
Leafing stabilizer, thickener,~inorganic or organic pigment
~and t~he-like. The typlcal examples of the organic pigments
include anthraquinones such as flavanthrone yellow,
indanthrone blue, dibromeanthanthrone red and anthrapyridine
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yellow, indigos, pyranthrones, perylenes and the like. The
typical examples of the inorganic pigments include
phthalocyanine blue, titanium white and the like.
The pigment composition according to the invention is
particularly suitable for incorporating in the water base
paint. The water base paint in which the composition is
incorporated is not particularly limited. For example, the
pigment composition according to the invention is
incorporated in the water-soluble paint or the aqueous
emulsion paint which contains polyester, acryl, alkyd,
acryl-urethane, CAB, polyvinyl alcohol, polyvinyl acetate or
ethylen0-vinyl acetate resin. O course, the pigment
composition according to the invention can be incorporated
in inks, adhesives and the like.
Examples:
The following examples illustrate the invention, but
are not to be construed as limiting the scope thereof.
Percentages are by weight otherwise statPd.
Examples 1 to 14 and Comparative Examples 1 to 6
A cake with A~ content of ~0 % was prepared by
rémoving a solvent from an aluminium paste pigment. The
aluminium paste pigment used was a commercial available
aluminium paste pigment ( 7160N produced by TOYO ALUMINIUM
K.K.~which essentially consists of aluminium flakes passing
through 400 mesh screen ( Tyler standard sieve ) and mineral ~-
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spirit-and the AQ content of which is 65 % . The
thus~prepared cake contained an oleic acid used as a
grinding agent in an amount of 1.5 parts by weight per 100
parts by weight of aluminium.
The cake was transferred into a mixer and the
ir.organic phosphoric acid, the aliphatic compound, the
nonionic surfactant, water, the water-compatible alcohol and
the hydrocarbon oil shown in Table 1 were added thereto and
kneaded for three hours to obtain an aluminium pigment
composition in a paste.
The phosphor content and the water content in the
thus-obtained composition were determined in accordance with
the following methods. The results are also shown in Table
1.
a) phosphorus content
Each sample was washed with a mixed solvent of water
and isopropanol and a mixed solvent of ether and acetone,
successively and then dried to remove the solvent. Then, the
sample was dissolved in an aqueous hydrochloric acid
solution.
The phosphor ( P ~ content ( ppm ) based on the
aluminium weight was determined by the plasma emission
spectrophotometry.
b) water content
The water in the sample was vaporized at 230C in N2
gas flow and condensed.
The water content ( parts by weight ) per 100 parts
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by weight of aluminium was determined in accordance with
Karl Fischer method by means of Moisture Meter VA-0.2 and
CA-0.2 ( produced by ~ITSUBISHI CHEMICAL INDUSTRIES LTD. ).
Example 15
The procedure of Example 10 was repeated to obtain a
pigment composition with AQ con-tent of about 52 % , provided
that the used cake contained stearic acid as the grinding
agent in an amount o~ 1.7 parts by weight per 100 parts by
weight of aluminium.
Example 16
A pigment composition with A~ content of about 52 %
was obtained in a similar manner to the procedure of Example
5. The used cake contained lauryl amine as the grinding
agent in an amount of 1.0 part by weight per 100 parts by
weight of aluminium.
Example 17
The water dispersibility, the aggregation amount, the
gas volume evolved in the water base paint and the change in
color tone of the paint film of each pigment obtained in the
above Examples and Comparative Examples were determined in
accordance with the following methods. The results are shown
in Table 2.
a) water dispersibility
A predetermined amount of the sample was added to the
pure water in the test tube. After stirring, the sample was
allowed to stand.
The dispersibility in water was observed with necked
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eyes and evaluated as follows:
: disperse easily and homogeneously
O : disperse almost homogeneously
L : almost leafing
b) aggregation amount
The sample after storing in a tank at 50~C for one
month was dispersed in water.
The weight of the sample not passing through 325 mesh
screen ( Tyler standard sieve ) was determined and expressed
as percentages based on the aluminium weight.
c) gas volume
The water base paint used consisted of 21.3 g
(calculated as aluminium) of the sample, 281.6 g of
ALMATEX ~A-911 t produced by MITSUI TOATSU CHEMICALS, INC.),
44 g of CYMEL~350 ( produced by MITSUI TOATSU CHEMICALS,
INC.), 7.1 ~ of phthalocyanine blue, 14.4 g of triethyl
amine, 34.6 g of isopropanol and 448.0 g of water. Eighty
grams of the above paint was transferred into the glass
bottle and stored at 50C for one month.
The total gas volume ( mQ ) evolved during the
storage was determined at the room temperature.
d~ change in color tone
The blue metallic paint film was formed by coating
lS0 microns in thickness of the a~ove paint on the glass
plate with a doctor blade and baking at 160C for 20
minutes. As the control, the blue metallic paint film was
formed in a similar manner using the untreated pigment
12
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obtained in Comparative Example 1.
The color difference ( ~E ) of the paint film over
the control paint film was determined by means of the
color-difference meter with 45- 0 mannerO
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Table 2
Examples water aggregated gas volume color
& Comp. dl spe rsi- amount difference
Examples bllity ( %) (ml) ~F.)
Æx. 1 0.05 not more than _ ;__
2 ~ 0.05 1 0O5
3 ~ 0.05 .- 0.5
4 ~ 0.03.. 0.4
O 0.02,. 0.4
0.02,. 0O4
7 ~ 0.02., 0~3
~ ~ 0.03., 0.4
9 ~ 0.03,. O.S
L 0.03.. 0.6
11 ~ 0.03.. 0.5
12 ~ 0.03 2 0.6
13 ~ 0.03not morle than 0.5
14 ~ 0.03,. 0.5
L 0.03.. 0.5
16 O 0.03 . 0.5 ,
. ._
Comp .
Ex. 1 O 0.02 more than 50_
2 ~ 0.0248 0.3
3 O 0.6 5 2.5
4 O 5.5 2 1~.5
O 7.3more than 509O4
6 _ ~ _ 1.5 _
16
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Effect of the Invention:
In the pigment composition according to the
invention, the thin and dense coatings are formed on the
surfaces of aluminium flakes. The coatings were covered w:ith
a large amount of long pendant residue of the aliphatic
compound since the functional groups in the aliphatic
compound adsorb or bind on the surfaces of aluminium flakes~
Therefore, the pigment composition according to the
invention has the improved water dispersibility as well as a
little tende~cy to evol~e a large volume o~ gas, aggregate
the flakes and darken the color tone of the paint film.
17
