Note: Descriptions are shown in the official language in which they were submitted.
:
11, 266-1
Q48
BACKGROUND OF THE INVENTIO~
This invention pertains to single-package zinc-rich
coatings and more particularly to blends of zinc,
partially hydrolyzed alkyl silicates and an aminosilane.
Zinc-rich coatings aré effective in protecting steel
against corrosion. The principle of this protective
action is attributed to the fact that zinc, being higher
than iron in the electromotive series of the elements re-
acts first in any environment conducive to the ionic dis-
solution (oxidation) of metals, thereby protecting the
steel substrate.
As the name implies, zinc-rich coatings contain a
high concentration of zinc in the dry film. This is
required so as to provide the electricaI continuity and,
therefore, the conductivity necessary for the electro-
chemical process to take place.
In order to obtain these zinc-rich coatings on a
ferrous substrate, a paint formulation containing very
fine zinc dust produced by distilling the ~etal under
controlled conditions of condensation is used. ~hen the
paint is applied, the metallic powder is held in place
on the surface by a binder matrix. Zinc-rich coatings
are classified, according to the nature of the binder,
into organic or inorganic coatings.
Organic zinc-rich coatings utilize synthetic
polymers as binders. Although such coatings afford
effective corrosion protection, their heat and solvent
resistance are limited.
~ r,
l~lOQ48 11266-1
Inorganic binders do not have these limitations.
Such binders include water-soluble silicates, which are
insolubilized by a curing composition after application,
and alkyl silicates which do not require post cure. Al-
though alkyl silicates contain organic chains, the result-
ing zinc-rich coatings are classified as inorganic be-
cause it is believed that, upon drying, a totally in-
organic matrix of SiO2 is formed. This reaction takes
place slowly and proceeds through continuous stages of
hydrolysis. The alkyl silicates that may be used in zinc-
rich coatings may vary in ~heir level of hydrolysis. If
an alkyl silicate having a very low level of hydrolysis
is used, the curing reaction is so slow that the film re-
mains uncured for prolonged periods of time. Using alkyl
silicates hydrolyzed to higher levels reduces the time
necessary to obtain dry films. Unfortunately as the dry-
ing time decreases due to the higher degree of hydrolysis,
the stability of the product in turn decreases. This
lower stability is manifested in various ways. One is an
2~ increasing tendency for the paint to gel in the container
upon storage. Another is a diminished pot life when alkyl
silicate is mixed with the zinc dust in which case gell-
ing usually occurs in a few hours.
One way to avoid insta~ility of the paint composi-
tion in the container and premature gellation with the
zinc, is to package the zinc separately from the alkyl
silicate and mix the two components just prior to appli-
cation.
11266-1
Q48
This is done commercially in the so-called 2-package
zinc-rich coating compositions and the field has adapted
its working methods to this characteristic of the product
or paint used to provide the coatings. However, the
problems inherent in a 2-component coating composition,
viz., doubled production, warehousing, stocking and inventory,
as well as metering and mixing on site coupled with limit-
ed pot life makes a single-component zinc-rich paint primer
composition very desirable.
If zinc-rich coatings are made with alkyl silicates
of low degrees of hydrolysis, stability of the alkyl sili-
cate in its container as well as the pot life of primer
composition after addition of the zinc dust to the alkyl
silicate improves considerably. The price of this im-
proved stability, however, is a much lengthened drying
time. The problem facing the formulator is therefore how
to obtain curing of a single-package alkyl silicate, zinc-
rich paint primer composition in a reasonably short time,
while maintaining good package stability in conjunction
with non-reactivity of the alkyl silicate with the zinc
dust.
Several proposed solutions for this problem have
been put forth in the prior art. Thus, for example in
U.S. 3,653,930 a single-package, zinc-rich coating was
obtained by the addition of low molecular weight amines
to ethyl silicate hydrolyzed to about 40% together with
nitro compounds to prevent gassing. The same general ap-
proach was also described in Netherlands Paten, No.
6,900,729.
~,
,
lllUQ48 11266-1
In U.S. 3,660,119 film formation of a 40% hydrolyzed
alkyl silicate was obtained through the use of strong
bases, such as, sodium or potassium methoxide or ethoxide.
U.S. 3,859,101 discloses use of zinc chromate instead
of nitro compounds as anti-gassing additives in a mixture
of alkyl silicate and zinc dust.
U.S. 3,917,648 utilizes a reaction product of alkyl
silicates with polyols to form a product which is stable
in the presence of zinc.
The prior art references recited above suffer the
following disadvantages:
1. Low molecular weight amines are volatile and
therefore alkyl binders containing them lost effective-
ness upon storage.
2. Low molecular weight amines are water-soluble
therefore introducting a factor of water sensitivity into
a coating primarily intended for corrosion protection.
3. Low molecular weight amines have high chemical
reactivity. Thus they react with acids such as those
produced by absorbed carbon dioxide during storage. This
may account for their loss of effectiveness with time.
Low molecular weight amines present in the coating
formed on the ferrous substrate have adverse effects on
the resistance of the zinc-rich film to environmental
-J,
~10~48 11266-1
agents and interfere with the adhesion and chemical
resistance of top coats applied to the primer coat.
5. Low molecular weight amines are toxic, rep-
resenting a potential safety hazard to those coming in
contact with the coating compositions.
6. Strong bases such as alkali metal alkoxides or
their corresponding hydroxide by-products adversely af-
fect a metal of amphoteric character such as zinc.
7. The alkali metal alkoxides or their correspond-
ing hydroxide by-products remain in the zinc-rich film
formed on the ferrous substrate, introducing an element
of water and chemical sensitivity which may affect the
performance of top coats applied to the primer coat.
8. Polyol silicate zinc-rich coatings produce
films which are softer than desirable.
It is therefore an object to the present invention
to provide a zinc-rich coating composition containing an
alkyl silicate which as a primer paint coating composition
remains stable when packaged for prolonged periods of
time. It is another object to provide coating composi-
tions which upon application to a ferrous substrate rapid-
ly form a dry, hard, corrosion-resistant protective primer
film.
SUMMARY OF THE INVENTION
The objectives enumerated above have been achieved
with compositions comprising particulate zinc, an un-
hydrolyzed or a partially hydrolyzed organic silicate
and a hardening amount of an hydrolyzable silicon com-
pound selected from the class consisting of:
1110~48 11266-1
(a) aminosilanes of the formula:
Q
Z---~N - Rl ~ N - Y
M
wherein:
t is an integer having values of 0 to 10;
each of M, Y, Q and Z are R or
Rb
- R - Si - X4_(a + b)
R is H, alkyl having 1 to 4 carbon atoms or
hydroxyalkyl having 2 to 3 carbon atoms;
C2H4-, -C3H6- or -R2-O-R2- and R2
is an alkylene radical having about 1 to 8 carbon
atoms;
a is an integer having values of 1 to 3;
b is an integ~r having values of 0 to 2;
and the sum of a + b C 3;
with the proviso that at least one of M, Q, Y or
z is
Rb
- R - Si - X4_(a + b);
x is an hydrolyzable organic group;
(b) quaternary ammonium salts of the amino-
silanes in ~a); and
(c) the hydrolyzates and the condensates of
the aminosilanes in (a).
The compositions described above are stable for
prolonged periods of time in a closed container. Thus
separate packaging is not required. When applied on a
ferrous substrate, the zinc-rich formulations dry rapidly
,i,
~10~48 11266-1
with the result that a hard, continuous, smooth film
is formed having excellent corrosion protecting properties.
The alkyl silicates used in this invention are known
in the art comprising unhydrolyzed alkyl and alkoxyalkyl
silicates and alkyl and alkoxyalkyl silicates hydrolyzed
up to about 40 per cent by weight. Alkyl silicates are
-~ produced by the reaction of silicon tetrachloride and
alcohols and alkoxy alcohols, generally in a reactor
equipped with a stirrer, condenser and vat scrubber. The
hydrogen chloride by-product is removed by reflux which
may be carried out at reduced or atmospheric pressure.
Through this process, the most common products TEOS
(tetraethyl orthosilicate), and Cellosolve (Trademark of
the Union Carbide Corporation for monoalkyl ethers of
ethylene glycol) silicate are made.
Subsequently these products may be partially hydroly-
zed by the addition of water and an acid catalyst. The
amount of water added determines the degree of hydrolysis
in the final product. Commercially available products
de~ived from ethanol include the unhydrolyzed TEOS,
Condenqed Ethyl Silicate (about 7 per cent hydrolysis),
Ethyl Silicate 40 (40 per cent hydrolysis containing
40% SiO2), and Ethyl Silicate P-18, having an 80 to 85
per cent hydrolysis level.
The hydrolyzable silicon compounds used in this in-
vention are also known in the art and include a wide
variety of compounds. Typical examples are gamma-
aminopropyltriethoxysilane having the formula:
~ 4~ 11266-1
l C2H5
HSC2 - Si - CH2CH2CH2NH2
OCH3
and N-beta(aminoethyl)-gamma-aminopropyltrimethoxy-
silane having the formula:
ICH3
CH30 - Si - CH2CH2C~2-NH-CH2CH2NH2
OCH3
Other exemplary aminosilanes include:
aminomethyltrimethoxysilane,
gamma-aminopropyltrimethoxysilane,
gamma-methylaminopropyltrimethoxysilane,
gamma-aminopropyltripropoxysilane,
gamma-aminopropylmethyldiethoxysilane,
gamma-aminopropylethyldiethoxysilane,
gamma-aminopropylphenyldiethoxysilane,
gamma-aminoisobutyltrimethoxysilane,
delta-aminobutyltriethoxysilane,
delta-aminobutylmethyldiethoxysilane,
beta-aminoethyltriethoxysilane,
epsilon-aminopentylphenyldibutoxysilane,
N-(beta-aminoethyl)-gamma-aminopropyl-
trimethoxysilane,
N-(beta-aminoethylaminoethyl)-gamma-
aminopropyltrimethoxysilane,
N-(gamma-aminopropyl)-gamma-aminoiso-
butylmethyldiethoxysilane,
N-(beta-aminoethyl)-gamma-aminopropyl-
triethoxysilane.
lllOQ48
C.~
11,266-1
In addition to the above-enumerated aminosilanes
which contain one silane group one can also use
xelated aminosilanes containing two or more silane
groups. Representati~e examples include:
N-beta[N'-gamma(trimethoxysilylpropyl)-amino-
ethyl]-gamma-aminopropyltrimethoxysilane
OCH3 H H OCH3
CH30-Si-(CH2)3N-CH2CH2 N (C 2)3, 3
OCH3 OCH3
N,N-beta~bis ~N'-gamma-(trimethoxysilylpropyl)
aminoethyl} -gamma-aminopropyltrimethoxysilane]
,OCH3 ,OCH3
CH30-Si-(CH2)3N-C~2CH2 N (C 233 , 3
OCH3 H (CH2)3 OCH3
CH30 - Si-OCH3
OCH3
N,N-betarbis ,tN',N'-gamma-bis(trimethoxysilyl-
propyl)aminoethyl)} -gamma-aminopropyltrimethoxysilane]
-- 10 --
1~10~48
11,266-1
OCH3
CH30 Si-OCH3
,OCH3 (,CH~)3 ,OCH3
CH3o-si-(cH2)3N-cH2cH2N-(cH2)3 Si 3
OCH3 (,C~2)3 OCH3
CH O -Si-OCH
3 3
OCH3
and the like.
~ 48 11266-1
A typical preparation of an alkoxysilylpropylamine
is contained in U.S. 2,832,754 wherein gamma-chloro-
propyltriethoxysilane and liquid ammonia in a ratio of
about 1 to 20 are charged into a pressure vessel heated
at a temperature of about ,100C. for 12 hours. After
cooling, filtering, washing and fractionally distilling
the mixture approximately 50 per cent of the desired
product is obtained.
Another method for the preparation of aminoalkyl-
trialkoxysilane is described in U.S. 2,930,809 wherein a
cyanoalkyltrichlorosilane described in U.S. 2,837,551 is
prepared followed by alcoholysis and hydrogenation. For
example, hexachlorodisilane and acrylonitrile in a 1:1
molar ratio are sealed in an autoclave heated to a temp-
erature of about 200C. for 2 hours. One of the products
obtained upon fractional distillation of the mixture is
beta-cyanoethyltrichlorosilane. Ethanolysis of this com-
pound yields beta-cyanoethyltriethoxysilane. The latter
compound is charged to a stainless steel pressure vessel
together with Raney nickel. The temperature of the ves-
sel is then cooled to -78C. and an excess of liquid
ammonia added. Hydrogen gas is charged into the system
and the mixture heated at a temperature of 100C. for
16 hours in a roc~ing autoclave. The mixture is then
cooled to room temperature, filtered, washed with di-
ethyl ether and fractionally distilled. One of the
products obtained is triethoxysilylpropylamine.
The hydrolyzates and condensates of the aminosilanes
described above can be prepared by the conventional
-12-
'~'
1110~48 11, 266-1
known methods of hydrolysis and condensation. As is
well known in the art, hydrolyzates represent the
metathetical reaction products of water and correspond-
ing hydrolyzable aminosilanes, while condensates repre-
sent the siloxane products obtained upon condensation
of the hydrolyzate reaction mixture. The amount of water
employed is not critical and merely depends upon the
degree of hydrolysis and condensation desired. Accordingly,
completely hydrolyzed as well as partially hydrolyzed
products can be provided.
The term "hardening amount of a hydrolyzable silicon
compound" is used in this invention to mean an amount
sufficient to afford a dry film of the coating composition
when placed on a ferrous substrate under ambient con-
ditions. It has been found that at least about 5% by
weight of hydrolyzable silicon compound, based on a weight
of partially hydrolyzed organic silicate, is required
to obtain a dry film within a practical exposure time,
that is, in about 5 to 10 minutes. There is no critical
upper limit but for practical purposes there is no ad-
vantage in using more than about 50% by weight of hydrolyz-
able silicon compound. It is preferred to use about 15
to about 45% by weight of hydrolyzable silicon compound.
Although not essential for the practice of this in-
vention, it is preferred that metal protective compositions
~ 48 11266-1
of this invention include a water scavenging agent.
Suitable water scavenging agents include zeolites,
silica gel, tetraalkyl silicates, trialkyl borates, and
the like. Zeolites are preferred because unlike the
others given above the scavenging or water removal
action does not produce a reaction product.
The zeolite water-scavenging agent can be any of
the well known three-dimensional crystalline zeolites
of the molecular sieve type, either naturally-occurring
10- or synthetically prepared by conventional hydrothermal
crystallization, and which have pore dimensions large
enough to permit the passage of water molecules. Typical
of the naturally occurring zeolites are clinoptilolite,
chabazite, gmelinite, mordenite, erionite, offretite,
phillipsite and faujasite. Illustrative of the syn-
thetic molecular sieve zeolites are zeolite A, U.S.P.
2,882,243; zeolite X, U.S.P. 2,882,244; zeolite R,
U.S.P. 3,030,181, zeolite S, U.S.P. 3,054,657; zeolite
T, U.S.P. 2,950,952; zeolite F, U.S.P. 2,996,358, zeo-
lite B, U.S.P. 3,008,803, zeolite M, U.S.P. 2,995,423;
zeolite H, U.S.P. 3,010,789; zeolite J, U.S.P. 3,011,809;
zeolite Y, U.S.P. 3,130,007; and zeolite L, U.S.P.
3,216,789. Advantageously the zeolite selected will
have a framework molar SiO2/A12O3 ratio of less than
50, and preferably less than 20, since the highly
siliceous zeolites tend to exhibit organophillic prop- i
erties to the detriment of their hydrophillic character-
istics. Particularly suitable, because of their ex-
tremely high water-sorp~ion capacity are the various
-14-
11266-1
~110~48
cation forms of zeolite A. The potassium cation form of
zeolite A, moreover, has an effective pore diameter of
between 3 and 4 Angstroms and thus is capable of readily
adsorbing water but effectively excludes most other
molecules in the system on the basis of molecular size.
For use as adsorbents, the zeolites should be
a~. least partially dehydrated, preferably fully de-
hydrated, by heating in air or vacuum at moderate temp-
eratures of about 250 to 350C. for several hours. Since
zeolite crystals are small, seldomly larger than 10
micrometers, they can suitably be admixed in the coat-
ing compositions without adversely affecting its es-
sential properties. Alternatively, the zeolite crystals
can be formed into shaped agglomerates with conventional
binders such as clays and enclosed in the container in
which the product is stored.
The invention is described in the Examples which
follow.
All parts and percentages are by weight unless
otherwise specified.
EXAMPLE 1
SINGLE-PACKAGE ZINC-RICH COATING
WITH ETHYL SILICATE 40 AND GAMMA-
AMINOPROPYLTRIETHOXYSILANE
A ferrous metal coating composition was prepared by
mixing 45 grams of partially hydrolyzed ethyl polysili-
cate containing 40 per cent by weight of SiO2, with 5
-15-
11,266-l
lll(~Q48
grams of gamma-aminopropyltriethoxysilane and 30 grams of
finally divided zinc having a particulate size of about 2
to about 15 microns (American Smelting and Refining Co.
ASARcoQ~L-lS). In addition, in order to maintain the mix-
ture in an anhydrous state, 5 grams of a water scavenging
agent (Union Carbide Corp. molecular sieves 4 A) were added
and the composition was thinned with 50 grams of a hydro-
carbon solvent consisting of a mixture of 61% by volume of
paraffinics and 39% by volume of naphthenics having a
boiling range of about 158-196C. of (American Mineral
Spirits Company Mineral Spirits 66-3). The resultant
liquid protective coating or primer paint had a package
stability of over six months.
When this paint was applied by spraying to sand
blasted, cold-rolled steel panels measuring approximately
4 inches by 4 inches by 1/8 inch, there was obtained a
smooth film which dried in less than ten minutes. The
steel panel so coated was subjected for 1000 hours to
salt spray (ASTM Method B-117) and 1000 hours in fresh
water immersion (ASTM Method B-870). There was no evidence
of corrosion or other signs of failure on the panel so
coated.
EXAMPLE 2
SINGLE PACKAGE ZINC-RICH COATING
WITH ETHYL SILICATE 40 and N-BETA-
(AMINOETHYL)-GAMMA-AMINOPROPYLTRI-
METHOXYSILANE
A ferrous metal coatirg composition was prepared
by mixing 45 grams of partially hydrolzed ethyl polysili-
cate containing 40~/O by weight of SiO2 with 5 grams of
-16-
~; ~
11,266-1
l~lQ~48
N-beta(aminoethyl)-gamma-aminopropyltrimethoxysilane and
300 grams of finely divided zinc dust (ASARC $ L-15), 5 grams
of a water scavenging agent (Union Carbide molecular
sieves 4A) and 50 grams of Amsco Mineral Spirits 66-3.
The resultant primer paint was stable for over six
months in storage. When applied to sand blasted steel
panels as in Example 1, the coating dried to a hard film
in less than 10 minutes. When these panels were sub-
jected to a salt spray and water immersion for 1000 hours,
they showed no evidences of corrosion or other failure.
EXAMPLE 3
SINGLE PACKAGE ZINC-RICH COATING
WITH TETRAETHYLORTHOSILICATE AND
N-BETA(AMINOETHYL)-GAMMA-AMINO-
PROPYLTRIMETHOXYSILANE
A ferrous metal protective composition was prepared
by mixing 45 grams of tetraethylorthosilicate with 5
grams of N-beta(aminoethyl)-gamma-aminopropylmethoxysilane
and 300 grams of ASARCO~ zinc dust L-15, 5 grams of mole-
cular sieves 4A, and 50 grams of Amsco Mineral Spirits 66-3.
The resultant primer paint was stable in stor~ge for over
six months. When applied as a spray coating to a sand
blasted steel panel, a dry film formed in less than ten
minutes. When panels were e~posed as in Example 1 for
1000 hours in the salt spray and water immersion test,
there was no evidence of corrosion or other failure.-
EXAMPLE 4
SINGLE PACKAGE ZINC-RICH COATING
WITH CELLOSOLVE SILICATE AND
GAMMA-AMINOPROPYLTRIETHOXYSILANE
A ferrous metal protective paint primer composition
was prepared by mixing 45 grams of partially hydrolyzed
-17-
1~10~48 11266-1
ethoxyethylpolysilicate containing 19% SiO2, 5 grams of
gamma-aminopropyltriethoxysilane, 300 grams of ASARCO
L-15 zinc dust, 5 grams of Molecular Sieves 4A and 50
grams of Amsco Mineral Spirits 66-3. The resultant primer
paint composition had a package stability of over six
months. When applied as a spray over sand blasted panels,
the composition dried to a hard film in less than ten
minutes. The panels, when subjected to the salt spray
and water immersion test described in Example 1 for 1000
hours, showed no evidence of corrosion or other failures.
EXAMPLE 5
SINGLE PACKAGE ZINC-RICH COATING
WITH TETRAETHYLORTHOSILICATE AND
POLY(AMINOA~KYL)DIMETHYLPOLYSILOXANE
A ferrous metal protective composition was prepared
by mixing 45 grams of tetraethylorthosilicate with 5 grams
of a poly(aminoalkyl) dimethylpolysiloxane, 300 grams of
ASARCO ~ zinc dust L-15, 5 grams of Molecular Sieves 4A,
and 50 grams of Amsco Mineral Spirits 66-3. The resultant
paint was stable in storage for over six months. When
this coating composition was applied to sand blasted steel
panels, it formed a dry film in less than ten minutes.
When similar panels were exposed for 1000 hours to salt
spray and water immersion as in Example 1, there was no
evidence of corrosion or other failure.
EXAl~IPLE 6
SINGLE PACKAGE ZINC-RICH COATIN~
T~ITH ETHYL SILICATE 40 AND AN
AMINOALKYLALKYLALKOXYSILANE
A ferrous metal protective composition was prepared
~ 8 11266-1
by mixing 45 grams of partially hydrolyzed ethyl poly-
silicate containing 40 weight % of SiO2 with 5 grams of
an aminoalkylalkylalkoxysilane (Union Carbide Silane
A-1902), 300 grams of ASARCO ~ zinc dust L-15, 5 grams of
molecular sieves 4A and 50 grams of Amsco Mineral Spirits
66-3. The resultant paint was stable for over six months
on storage. When this coating composition was applied to
sand blasted steel panels, it formed a dry film in less
than ten minutes. When simular panels were exposed for
1000 hours to salt spray and water immersion as in Ex-
ample 1, there was no evidence of corrosion or other
failure.
EXAMPLE 7
SINGLE PACKAGE ZINC-RICH COATING
WITH CELLOSOLVE SILICATE AND N-BETA
(AMINOETHYL)GAMMA-AMINOPROPYL-
TRIMETHOXYSILANE
A ferrous metal protective composition was prepared
by mixing 45 grams of partially hydrolyzed ethoxyethyl-
polysilicate, containing 10% SiO2, 10 grams of N-beta
(aminoethyl) gamma-aminopropyltrimethoxysilane, 300 grams
of ASARCO ~ zinc dust L-15, 5 grams of molecular sieves
4A, and 50 grams of Amsco Mineral Spirits 66-3. The re-
sultant paint was stable upon storage for over six months.
When this coating composition was applied to sand blasted
steel panels, it formed a dry film in less than ten min-
utes. When similarly coated panels were exposed for 1000
hours to salt spray and water immersion, as in Example 1,
there was no evidence of corrosion or other failure.
-19-
I~ ~
lllQ~8 11266-1
EXAMPLES 8-11
SINGLE PACKAGE ZINC-RICH COATINGS
WITH ETHYL SILICATE 40 AND VARYING
CONCENTRATIONS OF N-BETA(AMINOETHYL)
GAMMA-AMINOPROPYLTRIMETHOXYSILANE
Ferrous metal protective compositions were prepared
by mixing 45 grams of partially hydrolyzed ethyl poly-
silicate containing 40% by weight of SiO2, 2 grams of
molecular sieves 4A, 300 grams of ASARCO ~ zinc dust L-15
and 2, 5, 10 and 20 grams respectively of N-beta(amino-
ethyl) gamma-aminopropyltrimethoxysilane. In each Example
the resultant paints were stable for over six months.
When these paints were applied to sand blasted steel panels,
they formed dry films in less than ten minutes. When
similarly prepared panels were exposed for 1000 hours to
salt spray and water immersion, as in Example 1, there
was no evidence of corrosion or other failure.
EXAMPLES 12-15
SINGLE PACKAGE ZINC-RICH COATINGS
WITH VARYING RATIOS OF N-BETA
(AMINOETHYL)GAMMA-AMINOPROPYLTRI-
METHOXYSILANE AND MICA
Ferrous metal protective compositions were prepared
by mixing the following components:
E X A M P L E
Component _ 13 14 15_
ASARCO ~ Zinc Dust L-15600g 600g 600g 600g
Mica 40g 40g 40g 40g
Molecular Sieve 4A 4g 4g 4g 4g
Partially hydrolyzed ethyl
silicate containing 40%
Si~2 109g105.5g 102g 98.5g
Union Carbide Silicone
A-1120(a) llg22.5g 33g 45g
-2~-
1110048 11266-1
(a) N-beta (aminoethyl) gamma-aminopropyltrimethoxy-
silane.
The resultant paints were stable for over six months.
The resultant paints when applied to sand blasted panels
formed a dry film in less than ten minutes. These coated
panels when exposed for 1000 hours to salt spray and water
immersion, as in Example 1, showed no evidence of corros-
ion or other failure.
EXAMPLE 16
SINGLE PACKAGE ZINC-RICH COATING
WITH ETHYL SILICATE 40 AND N
(BETA-ETHYLENEDIAMINOETHYL)-BETA-
AMINOETHYLTRIMETHOXYSILANE
A ferrous metal coating composition was prepared by
mixing 45 grams of partially hydrolyzed ethyl polysili-
cates containing 40~/O SiO2, 10 grams of N-(beta-ethylene
diaminoethyl)-beta-aminoethyltrimethoxysilane, 300 grams of
ASARCO ~ zinc dust L-15, and 5 grams of molecular sieves
4A. The resultant paint was stable for over six months.
When the resultant coating composition was applied to
sand blasted steel panels, a dry film was obtained in less
than ten minutes. Panels so coated and subjected to salt
spray and water immersion, as in Example 1, showed no
evidence of corrosion or other failure.
EXAMPLE 17
SINGLE PACKAGE ZINC-RICH COATING
WITH ETHYL SILICATE 40 and GA~DIA-
N-(GAMMA-BUTYLAMINO)PROPYLT~I-
METHOXYSILANE
A ferrous metal coating composition was prepared by
mixing 45 grams of partially hydrolyzed ethyl polysilicate
containing 40% SiO2, 10 grams of gamma-N-(gamma-butylamino)
-21-
~l~OQ48 11266-l
propyltrimethoxysilane, 300 grams of ASARCO ~ zinc dust
L-15, and 5 grams of molecular sieves 4A. The resulting
paint was stable for over six months.
When this coating was applied to a sand blasted
steel panel, a dry film was obtained in less than ten
minutes. These panels, so coated, and subjected to salt
spray and water immersion, as in Example l, showed no
evidence of corrosion or other failure.
EXAMPLE 18
SINGLE PACKAGE ZINC-RICH COATING
WITH ETHYL SILICATE 40 AND N,N
BETA-(BIS-HYDROXYETHYL)-GAMMA-
AMINOPROPYLTRI~THOXYSILANE
A ferrous metal coating composition was prepared by
mixing 45 grams of partially hydrolyzed ethyl polysilicate
containing 40~/O SiO2 with 10 grams of N,N beta-(bis-hydroxy-
ethyl)-gamma-aminopropyltriethoxysilane, 300 grams of
ASARCO Q zinc dust L-15, and 5 grams of Molecular Sieves
4A. The resultant paint was stable for over six months.
When this coating was applied to a sand blasted steel
panel, a dry film was obtained in less than ten minutes.
Panels so coated subjected to salt spray and water im-
mersion for 1000 hours, as in Example 1, did not show
evidence of corrosion or other failure.
EXAMPLE 19
SINGLE PACKAGE ZINC-RICH COATING
WITH ETHYL SILICATE 40 AND POLYAMINO-
ALKYLTRIALKOXYSILANE
A ferrous metal coating composition was prepared by
mixing 45 grams of partially hydrolyzed ethyl polysilicate
containing 40% SiO2 with 10 grams of polyaminoalkyltri-
~10~48 11266-1
alkoxysilane, 300 grams of ASARCO ~ zinc dust L-15, and
5 grams of Molecular Sieves 4A. This paint was stable
for over six months.
When this coating was applied to a sand blasted steel
panel, a dry film was obtained in less than ten minutes.
Panels so coated subjected to salt spray and water immers-
ion for 1000 hours, as in Example 1, did not show evidence
of corrosion or other failure.
EXAMPLE 20
SINGLE PACKAGE ZINC-RICH COATING
WITH ETHYL SILICATE 40 AND GAMMA-
N,N-DIMETHYLAMMONIUMPROPYLTRI-
METHOXYSILANE ACETATE
A ferrous metal coating composition was prepared by
mixing 45 grams of partially hydrolyzed ethyl polysilicate
containing 40% SiO2 with 10 grams of gamma-N,N-dimethyl-
ammoniumpropyltrimethoxysilane acetate, 300 grams of
ASARCO ~ zinc dust L-15, and 5 grams of Molecular Sieves
4A. The resulting paint was stable for over six months.
When this coating was applied to a sand blasted steel
panel, a dry film was obtained in less than ten minutes.
Panels so coated subjected to salt spray and water im-
mersion for 1000 hours, as in Example 1, did not show
evidence of corrosion or other failure.
EXAMPLE 21
SINGLE-PACKAGE ZINC-RICH COATING
WITH CONDUCTIVE EXTENDER PIGMENT
A ferrous metal coating composition was prepared by
mixing 45 grams of partially hydrolyzed ethyl polysilicate
containing 40% SiO2 with 5 grams of Union Carbide Silane
A-1120, 200 grams of ASARCO ~ zinc dust L-15, 100 grams of
-23-
1110~48 11266-1
ferrous phosphite (an electrically conductive extender
pigment available commercially as "Ferrophos" ~ 2131,
~rom Hooker Chemical Co., with a mean particle size of 6
microns), 5 grams of Molecular Sieves 4A, and 50 grams of
Amsco Mineral Spirits 66-3. The resulting paint was
stable for over six months.
EXAMPLE 22
SINGLE PACKAGE ZINC-RICH COATING
WITH ETHYL SILICATE 40 AND N-BETA-
[N'-GAMMA(TRIMETHOXYSILYLPROPYL)-
AMINOETHYL]-GAMMA AMINOPROPYLTRI-
METHOXY SILANE
A ferrous metal coating composition was prepared by
mixing 155.2 grams of partially hydrolyzed ethyl poly-
silicate containing 40 percent by weight of SiO2 with 38.8
grams of N-beta[N'-gamma(trimethoxysilylpropyl)-amino-
ethyl]-gamma aminopropyltrimethoxy silane and 892.5 grams
of finely divided zinc having a particulate size of about
2 to about 15 microns (American Smelting and Refining Co.
ASARCO ~ -L-15), and 74 grams of a finely divided extender
(Water-Ground Mica 325, of The English Mica Co.). In ad-
dition, in order to maintain the mixture in an anhydrous
state, 7.5 grams of a water scavenging agent (Union Carbide
Corp. Molecular Sieves 4A) were added and the composition
was thinned with 293.5 grams of ethylene glycol monoethyl
ether (CELLOSOLVE ~ ). An antisettling agent was used to
prevent hard settling (24 g of MPA-60-X, a hydrogenerated
castor oil, of NL Industries) and 15.5 g of a thickener
(Ethocel ~ Medium Premium 100, of Dow Chemical Co., was
added to give desired viscosity). The resultant ethyl
silicate liquid protective coating or primer paint had
-24-
~ 8 11266-1
a package stability of over 3 months.
When this paint was applied by spraying to sand
blasted, cold-rolled steel panels measuring approximately
4 inches by 8 inches by 1/8 inch, there was obtained a
smooth film which dried in less than ten minutes. The
steel panel so coated was subjected for 500 hours to salt
spray (ASTM Method B-117) and there was no evidence of
corrosion or other signs of failure on th~ panel so coated.
EXAMPLE 23
SINGLE PACKAGE ZINC-RICH COATING
WITH ETHYL SILICATE 40 AND N-BETA-
[N'-GAMMA(TRIMETHOXYSILYLPROPYL)-
AMINOETHYL]-GAMMA AMINOPROPYLTRI-
METHOXY SILANE
A ferrous metal coating composition was prepared by
mixing 174.6 grams of Ethyl Silicate 40 with 19.4 grams of
N-beta~N'-gamma(trimethoxysilylpropyl)-aminoethyl]-gamma
aminopropyltrimethoxy silane, 892.5 grams of finely divid-
ed zinc dust (ASARCO ~ L-15), 7.5 grams of a water scaveng-
ing agent (Union Carbide Molecular Sieves 4A) 74 grams of
Mica 325, 24 grams of MPA ~-60-X, 15.5 grams of Ethocel
Medium Premium 100, and 293.5 grams of CELLOSOLVE ~.
The resultant primer paint was stable for 3 months
in storage. When applied to sand blasted steel panels as
in Example 1, the coating dried to a hard film in less
than 10 minutes. When these panels were subjected to a
salt spray and water immersion for 500 hours, they showed
no evidences of corrosion or other failure.
48
C' 11,266-1
Although the invention has been described in
its preferred forms with a certain degree of particularity,
it is understood that the present disclosure has been made
without departing from the spirit and scope of the
invention.
26.
