A water-based fluoroelastomer coating composition improved in adhesiveness onto a substrate, which comprises (A) an aqueous fluoroelastomer dispersion blended with (B) an aminosilane compound of the formula: ##STR1## wherein R is methyl or ethyl, X is a single bond, ##STR2## and y is an integer of 2 or 3 and optionally with (C) an amine compound having at least one terminal amino group directly bonded to an aliphatic hydrocarbon residue.

The present invention relates to a water-based fluoroelastomer coating 
composition. More particularly, it relates to a water-based 
fluoroelastomer coating composition improved in adhesiveness onto a 
substrate. 
Fluoroelastomers have excellent heat, weather, oil, solvent and chemical 
resistances so that various substrates such as fabrics, fibers, metals, 
plastics, etc. are coated or impregnated with compositions comprising the 
fluoroelastomers. 
There is known a solvent type fluoroelastomer coating composition which 
comprises a fluoroelastomer and an organic solvent blended with an 
aminosilane compound as a vulcanizing agent to improve its adhesiveness 
onto a substrate (cf. Japanese Patent Publication (examined) No. 
18346/1972). Although this coating composition assures a good adhesion 
onto the surface of a substrate, the essential use of an organic solvent 
is not favorable from the viewpoint of economy and safety. There is also 
known a water-based fluoroelastomer coating composition comprising an 
aqueous fluoroelastomer dispersion blended with a polyamine compound (e.g. 
hexamethylenediamine carbamate, N,N-dicynnamylidene-1,6-hexanediamine) as 
a vulcanizing agent (cf. DuPont's "Viton", Bulletin, No. 5, April, 1961). 
Since, however, the coating composition of this type does not have a 
satisfactory adhesiveness, the roughening (e.g. blasting) of the surface 
of a substrate and/or the use of any appropriate adhesive agent are 
required. 
As the result of an extensive study, it has now been found that the 
incorporation of a certain specific aminosilane compound into a 
water-based fluoroelastomer coating composition improves remarkably the 
adhesiveness onto a substrate so that the roughening procedure and the use 
of any adhesive agent can be omitted. When the aminosilane compound is 
incorporated together with a certain specific amine compound, enhancement 
of the physical properties, particularly tensile strength, of a coating 
film resulting from the coating composition is produced in addition to 
improvement of the adhesiveness onto a substrate. In addition, it is 
advantageous that the pot life of the said coating composition is much 
longer than that of a solvent type fluoroelastomer coating composition. It 
is also advantageous that on spray-coating, the said coating composition 
does not produce any cobwebbing even when it contains the fluoroelastomer 
at a high concentration. 
Accordingly, a main object of the present invention is to provide a 
water-based fluoroelastomer coating composition improved in adhesiveness 
onto a substrate with or without enhancement of the tensile strength of a 
coating film resulting therefrom. 
The water-based fluoroelastomer coating composition of this invention 
comprises (A) an aqueous fluoroelastomer dispersion blended with (B) an 
aminosilane compound of the formula: 
##STR3## 
wherein R is methyl or ethyl, X is a single bond, 
##STR4## 
and y is an integer of 2 or 3 and optionally with (C) an amine compound 
having at least one terminal amino group directly bonded to an aliphatic 
hydrocarbon residue. 
The fluoroelastomer used in the invention is a highly fluorinated elastic 
copolymer, preferably an elastic copolymer comprising units of vinylidene 
fluoride with units of at least one of other fluorine-containing 
ethylenically unsaturated monomers and having, for instance, a vinylidene 
fluoride unit content of not less than 40 mol%. A typical example of such 
favorable elastic copolymers is an iodine-containing fluoroelastomer, 
which comprises a polymeric chain essentially consisting of units of 
vinylidene fluoride and of at least one of other fluoroolefins 
copolymerizable therewith and an iodine atom(s) bonded at the terminal 
position(s) of the polymeric chain in an amount of 0.001 to 10% by weight, 
preferably of 0.01 to 5% by weight on the basis of the weight of the 
elastomer (cf. Japanese Patent Publication (unexamined) No. 40543/1977). 
Examples of the other fluorine-containing ethylenically unsaturated 
monomers are hexafluoropropene, pentafluoropropene, trifluoroethylene, 
trifluorochloroethylene, tetrafluoroethylene, vinyl fluoride, 
perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), 
perfluoro(propyl vinyl ether), etc. Among various fluoroelastomers, 
preferred are vinylidene fluoride/hexafluoropropene copolymer and 
vinylidene fluoride/tetrafluoroethylene/hexafluoropropene terpolymer. 
As the aqueous fluoroelastomer dispersion, there may be used a 
fluoroelastomer emulsion obtained by emulsion polymerization of the said 
monomers. There may be also used an aqueous dispersion of the 
fluoroelastomer obtained by emulsion, suspension or bulk polymerization of 
the said monomers, collecting the produced fluoroelastomer from the 
reaction mixture, pulverizing the collected fluoroelastomer and 
redispersing the pulverized fluoroelastomer into water, if necessary, by 
the aid of a surfactant. The fluoroelastomer content in the aqueous 
dispersion may be from 10 to 70% by weight, preferably from 30 to 60% by 
weight. Such fluoroelastomer content can be readily attained by 
concentration or dilution. When desired, the aqueous fluoroelastomer 
dispersion may comprise any conventional additive such as a pigment, an 
acid acceptor or a filler in addition to the fluoroelastomer. 
The aminosilane compound (I) acts as a vulcanizing agent and contributes in 
improvement of the adhesiveness of the coating composition. In this 
connection, it may be noted that for improvement of the adhesiveness of a 
solvent type fluoroelastomer coating composition, numerous and various 
kinds of aminosilane compounds are usable, but for improvement of the 
adhesiveness of a water-based fluoroelastomer coating composition as used 
in this invention, only the aminosilane compound representable by the 
formula (I) is usable, because the aminosilane compound (I) does not cause 
gellation, while the other aminosilane compounds do. Examples of the 
aminosilane compound (I) are as follows: 
.gamma.-aminopropyltrimethoxysilane, .gamma.-aminopropyltriethoxysilane, 
.gamma.-(.beta.-aminoethyl)aminopropyltrimethoxysilane, 
.gamma.-(.beta.-aminoethyl)aminopropyltriethoxysilane, 
.gamma.-(.beta.-aminoethyl)aminopropylmethyldimethoxysilane, 
.gamma.-ureidopropyltriethoxysilane, 
.gamma.-(.beta.-(.beta.-aminoethyl)aminoethyl)aminopropyltrimethoxysilane, 
etc. These aminosilane compounds may be used as such but their use in a 
partially or wholly hydrolyzed form is favored in assuring a highly 
improved effect without gelation. Hydrolysis may be effected, for 
instance, by treatment of the aminosilane compound with water to convert 
at least a part of the alkoxy group(s) represented by --OR into --OH. 
The amine compound usable as the optional component serves as a vulcanizing 
agent. Their typical examples are monoamines (e.g. ethylamine, 
propylamine, butylamine, benzylamine, allylamine, n-amylamine, 
ethanolamine), diamines (e.g. ethylenediamine, trimethylenediamine, 
tetramethylenediamine, hexamethylenediamine, 
3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, polyamines 
(e.g. diethylenetriamine, triethylenetetramine, pentaethylenehexamine). 
Among them, the ones having at least two terminal amino groups are 
preferred, and 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane 
is the most preferred. 
The water-based fluoroelastomer coating composition of the invention may be 
prepared by adding the aminosilane compound (I) and optionally the amine 
compound to an aqueous fluoroelastomer dispersion, followed by thorough 
agitation to make a uniform mixture. When used, a conventional additive(s) 
such as a pigment, an acid acceptor and a filler may be incorporated 
therein before, during and/or after the addition of the aminosilane 
compound (I) and/or the amine compound. As stated hereinbefore, the use of 
the aminosilane compound (I) as previously hydrolyzed is favorable in 
prevention of the resulting coating composition from gellation. 
When the aminosilane compound (I) is used alone, i.e. without the amine 
compound, its amount to be added may be from 1 to 30 parts by weight, 
preferably from 2 to 20 parts by weight, to 100 parts by weight of the 
fluoroelastomer. When the amine compound is employed, the combined amount 
of the aminosilane compound (I) and the amine compound is usually from 0.5 
to 30 parts by weight, preferably from 1 to 20 parts by weight, to 100 
parts by weight of the fluoroelastomer, the molar proportion of the 
aminosilane compound (I) and the amine compound being from 1:99 to 80:20. 
The acid acceptor may be a conventional one, of which specific examples are 
oxides and hydroxides of divalent metals (e.g. magnesium, calcium, zinc, 
lead). Examples of the filler are silica, clay, talc, diatomaceous earth, 
carbon, etc. 
The water-based fluoroelastomer coating composition of the invention may be 
coated on or impregnated into a substrate by a per se conventional 
procedure (e.g. brush-coating, dip-coating, spray-coating) and cured at 
temperature ranging from room temperature (e.g. 15.degree. C.) to 
200.degree. C. for a sufficient period of time to form a film having an 
excellent adhesiveness onto a substrate and a greatly improved tensile 
strength. 
As stated above, the water-based fluoroelastomer coating composition of the 
invention is greatly improved in its adhesiveness and tensile strength in 
comparison with a conventional water-based fluoroelastomer coating 
composition. It has a longer pot life (e.g. a period of 2 weeks to 1 month 
at 25.degree. C.) than a solvent type fluoroelastomer coating composition 
(e.g. about 10 hours at 25.degree. C.) and never causes cobwebbing even at 
high fluoroelastomer concentrations (e.g. 60% by weight) so that it is 
very easily handled while using and can afford a coating film of large 
thickness. Since no organic solvent is contained therein, it is 
non-flammable and hardly causes any pollution of the environment. 
The water-based fluoroelastomer coating composition of the invention may be 
used as a corrosion preventing coating composition or a protecting coating 
composition in various industrial fields and also used as a sealing 
material or an adhesive agent. Further, it can be used as an 
electroconductive coating composition. 
The present invention will be hereinafter explained in detail by the 
following Examples, in which part(s) and % are by weight unless otherwise 
indicated.

EXAMPLES 1 TO 4 AND COMATIVE EXAMPLES 1 TO 3 
(Scratch test) 
Mixtures A and B having the following compositions were mixed together in a 
weight proportion of 100:5 and filtered through a 200 mesh wire net to 
obtain a water-based fluoroelastomer coating composition: 
______________________________________ 
Mixture A Parts 
Aqueous fluoroelastomer 166 
dispersion (fluoroelastomer 
content, 60%; containing a 
non-ionic surfactant "Nissan 
Nonion HS 208" produced by 
Nippon Oil and Fats Co., Ltd.) 
Magnesium oxide 5 
Medium thermal carbon 30 
"Nissan Nonion HS 208" 2 
(a non-ionic surfactant produced 
by Nippon Oil and Fats Co., Ltd.) 
Water 50 
Mixture B Parts 
Aminosilane compound 90 
Weight ratio 
Magnesium oxide 3 
Medium thermal 20 
carbon 10 
"Nissan Nonion HS 208" 
2 
Water 50 
______________________________________ 
An aluminum plate of 100 mm in length, 50 mm in width and 1 mm in thickness 
was degreased with acetone. Onto the thus degreased plate, the above 
prepared coating composition was spray-coated and dried at a temperature 
of 50.degree. to 70.degree. C. for 10 minutes. Spray-coating and drying 
were repeated two more times to make a film of from 100 to 150.mu. in 
thickness. Then, the film was cured at 150.degree. C. for 1.5 hours. The 
cured film was subjected to scratch test according to JIS (Japanese 
Industrial Standard) K 6894 to examine the film characteristics. The 
results were evaluated by five ranks and are shown in Table 1. For 
comparison, the above operations were repeated but using an amine compound 
in place of the aminosilane compound. The results are also shown in Table 
1. 
TABLE 1 
______________________________________ 
Aminosilane compound*.sup.1 
Evaluation in 
Example*.sup.3 
or amine compound 
scratch test 
______________________________________ 
1 A-1100 5 
2 A-1120 5 
3 A-1160 4-5 
4*.sup.2 A-1100 5 
Comparative A-1125 Coating im- 
1 possible due 
to gelation 
Comparative N,N-Dicinnamylidene- 
1-2 
2 1,6-hexanediamine 
Comparative 3,9-Bis(3-amino- 
1 
3 propyl)-2,4,8,10- 
tetraoxaspirol[5.5]un- 
decane 
______________________________________ 
Notes:- 
*.sup.1 A1100: NH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 Si(OCH.sub.2 
CH.sub.3).sub.3 ; A1120: NH.sub.2 CH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 
CH.sub.2 Si(OCH.sub.3).sub.3 ; A1160: NH.sub.2 CONHCH.sub.2 CH.sub.2 
CH.sub.2 Si(OCH.sub.2 CH.sub.3).sub.3 ; A1125: CH.sub.3 COCH.sub.2 
CH.sub.2 NHCH.sub.2 CH.sub.2 NH--CH.sub.2 CH.sub.2 CH.sub.2 
Si(OCH.sub.3).sub.3 (aminosilane compound having no terminal amino 
*.sup.2 In Example 4, the aminosilane compound A1100 was previously 
completely hydrolyzed by water to NH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 
Si(OH).sub.3. 
*.sup.3 In Examples 1 to 3, the fluoroelastomer dispersion was gelatinite 
very slightly, but in Example 4, no gelation occurred. 
EXAMPLES 5 TO 7 AND COMATIVE EXAMPLE 4 
(Peel strength test) 
In the same manner as in Example 1, a film was formed on a substrate. The 
film was cut into a strip of 10 mm in width to the extent that the 
substrate was slightly flawed and then subjected to 180 degree peel test, 
in which one end of the strip was pulled by the aid of an autograph 
"IS-500" manufactured by Shimadzu Corp. at 24.degree. C. at a rate of 
50.0.+-.2.5 mm/min. The results are shown in Table 2. For comparison, the 
above operation was repeated but using an amine compound in place of the 
aminosilane compound. The results are also shown in Table 2. 
TABLE 2 
______________________________________ 
Comparative 
Example .sup.*1 
5 6 7 4 
______________________________________ 
Aminosilane 
A-1100 A-1100 A-1100 3,9-Bis(3- 
compound aminopropyl)- 
or amine 2,4,8,10- 
compound tetraoxaspiro- 
[5.5]undecane 
Substrate Alumi- Alumi- Iron Iron plate 
num num plate 
plate plate 
Blast Not Done Done Done 
finishing.sup.*2 
Peel strength 
2.53 2.51 2.03 0.15 
(kg/cm) 
______________________________________ 
Notes: 
.sup.*1 In Examples 5 to 7, the film was not peeled off but broken, and 
therefore the peel strength was indicated by a value at break. In 
Comparative Example 4, separation between the substrate and the film was 
produced, and thus the peel strength was indicated by a value at 
separation. 
.sup.*2 Blast finishing was effected by blasting 80 mesh Tosa emery at a 
wind loading of 5 kg/cm.sup.2. 
EXAMPLE 8 
(Film property test) 
In the same manner as in Example 1 but varying the amount of the 
aminosilane compound A-1100, water-based fluoroelastomer coating 
compositions were prepared. Each coating composition was spray-coated by a 
spray gun onto a polytetrafluoroethylene-coated aluminum plate and dried. 
These operations were repeated two more times. Thereafter, curing was 
effected at 150.degree. C. for 1.5 hours to form a film of about 100.mu. 
in thickness. The resulting film was peeled off from the plate and 
subjected to test for 100% modulus, tensile strength and elongation 
according to JIS K 6301. The results are shown in Table 3. 
TABLE 3 
______________________________________ 
A-1100 100% Modulus Tensile strength 
Elongation 
(parts).sup.*1 
(kg/cm.sup.2) 
(kg/cm.sup.2) 
(%) 
______________________________________ 
5 24 77 500 
10 40 82 240 
15 83 98 140 
20 95 102 110 
______________________________________ 
Note: 
.sup.*1 The amount of A1100 is based on 100 parts of the fluoroelastomer. 
EXAMPLE 9 AND COMATIVE EXAMPLE 5 
(Pot life and spray coating tests) 
Mixtures A and B having the following compositions were mixed together in a 
weight proportion of 100:5 as in Example 1 to give a water-based 
fluoroelastomer coating composition: 
______________________________________ 
Mixture A Parts 
______________________________________ 
Aqueous fluoroleastomer 
166 
dispersion (fluoroelastomer 
content, 60%; containing a 
non-ionic surfactant "Nissan 
Nonion HS 208") 
Magnesium oxide 3 
Medium thermal carbon 20 
"Nissan Nonoin HS 210" 2 
(a non-ionic surfactant produced 
by Nippon Oil and Fats Co., Ltd.) 
Water 50 
______________________________________ 
Mixture B Parts 
______________________________________ 
A-1100 90 
water 10 
______________________________________ 
For comparison, the following Mixtures A and B were mixed together in a 
weight proportion of 100:22.2 in the same manner as above to give a 
solvent type fluoroelastomer coating composition: 
______________________________________ 
Mixture A Parts 
______________________________________ 
Fluoroelastomer 100 
Magnesium oxide 3 
Medium thermal carbon 
20 
Methyl ethyl ketone 
225 
Methyl isobutyl ketone 
90 
______________________________________ 
Mixture B Parts 
______________________________________ 
A-1100 10.8 
Ethanol 89.2 
______________________________________ 
The fluoroelastomer coating composition was charged into a glass bottle 
with a lid and allowed to stand at 24.degree. C. to test the pot life of 
the coating composition. In case of the water-based coating composition 
(Example 9), gelation of the solid components occurred after 30 days, and 
it was impossible to redisperse the gel. In case of the solvent type 
coating composition (Comparative Example 5), gradual increase of viscosity 
was observed after 4 hours, and the whole coating composition became gel 
after 8 hours. 
The fluoroelastomer coating composition was spray-coated on an aluminum 
plate with a spray nozzle of 0.8 mm in diameter under a spray pressure of 
3.0 kg/cm.sup.2. In case of the solvent type coating composition 
(Comparative Example 5), cobwebbing occurred immediately after the start 
of spraying, but in case of the water-based coating composition (Example 
9), spraying could be done without any trouble to form an even film. 
EXAMPLES 10 TO 14 AND COMATIVE EXAMPLES 6 TO 19 
(Film property test) 
To Mixture A having the following composition, Mixtures B and/or C having 
the following compositions were added to make a homogeneous mixture 
containing the designed amount(s) of the aminosilane compound and/or the 
amine compound, which was then filtered through a 200 mesh wire net to 
obtain a water-based fluoroelastomer coating composition: 
______________________________________ 
Mixture A Parts 
______________________________________ 
Aqueous fluoroelastomer 
166 
dispersion (fluoroelastomer 
content, 60%; containing a 
non-ionic surfactant "Nissan 
Nonion HS 208") 
Magnesium oxide 3 
Medium thermal carbon 
20 
"Nissan Nonion HS 208" 
2 
Water 50 
______________________________________ 
Mixture B Parts 
______________________________________ 
Aminosilane compound 50 
Water 50 
______________________________________ 
Mixture C Parts 
______________________________________ 
Amine compound 50 
Water 50 
______________________________________ 
The coating composition was spray-coated by a spray gun on a 
polytetrafluoroethylene-coated aluminum plate and dried. These operations 
were repeated two more times, followed by curing at 150.degree. C. for 30 
minutes to make a film of about 150.mu. in thickness. The film was peeled 
off from the plate and subjected to test for tensile strength according to 
JIS K 6301. The results are shown in Table 4. 
In the same manner as above but using A-1125 (i.e. CH.sub.3 COCH.sub.2 
CH.sub.2 NHCH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 CH.sub.2 
Si(OCH.sub.3).sub.3), which is an aminosilane compound having no terminal 
amino group, in place of A-1100, a coating composition was prepared. 
However, the whole of the coating was gelatinized and could not be used 
for coating. 
TABLE 4 
______________________________________ 
Aminosilane Tensile 
compound Amine compound strength 
Example (mole)*.sup.1 
(mole)*.sup.1 (kg/cm.sup.2) 
______________________________________ 
10 A-1100 3,9-Bis(3-aminopropyl)- 
115 
(0.005) 2,4,8,10-tetraoxaspiro- 
[5.5]undecane 
(0.005) 
11 A-1100 Ethylenediamine 68 
(0.005) (0.005) 
12 A-1100 Ethanolamine 59 
(0.005) (0.005) 
13 A-1100 Triethylenetetramine 
92 
(0.005) (0.005) 
14 A-1100 -- 48 
(0.01) 
Comparative 
-- 3,9-Bis(3-aminopropyl)- 
93 
6 2,4,8,10-tetraoxaspiro- 
[5.5]undecane 
(0.01) 
Comparative 
-- Ethylenediamine 60 
7 (0.01) 
Comparative 
-- Ethanolamine 46 
8 (0.01) 
Comparative 
-- Tetraethylenetetramine 
85 
9 (0.01) 
Comparative 
-- Hexamethylenediamine 
93 
10 carbamate 
(0.01) 
Comparative 
-- N,N'-Dicinnamylidene- 
47 
11 1,6-hexanediamine 
(0.01) 
Comparative 
-- m-Phenylenediamine 
30 
12 (0.01) 
Comparative 
-- Benzidine 27 
13 (0.01) 
Comparative 
-- p,p'-Diaminodiphenyl 
29 
14 ether 
(0.01) 
Comparative 
A-1100 Hexamethylenediamine 
78 
15 (0.05) (0.005) 
Comparative 
A-1100 N,N'-Dicinnamylidene- 
Coating 
16 (0.05) 1,6-hexanediamine 
impossi- 
(0.005) ble due 
to gel- 
ation 
Comparative 
A-1100 m-Phenylenediamine 
46 
17 (0.05) (0.005) 
Comparative 
A-1100 Benzidine 47 
18 (0.05) (0.005) 
Comparative 
A-1100 p,p'-Diaminodiphenyl 
48 
19 (0.05) ether 
(0.005) 
______________________________________ 
Note: 
*.sup.1 Mol on the basis of 100 grams of the fluoroelastomer. 
EXAMPLES 15 TO 20 AND COMATIVE EXAMPLE 20 
(Film property and peeling tests) 
In the same manner as in Example 10 but varying the amounts of the 
aminosilane compound and the amine compound, fluoroelastomer coating 
compositions were prepared. The film prepared from the coating composition 
was subjected to test for tensile strength according to JIS K 6301. For 
comparison, a water-based fluoroelastomer coating composition prepared in 
the same manner as in Example 10 was spray-coated on an iron plate 
previously degreased with acetone and dried at a temperature of 50.degree. 
to 70.degree. C. for 10 minutes. These operations were repeated two more 
times to form a film of from 100 to 150.mu. in thickness, which was cured 
at 150.degree. C. for 0.5 hour. The thus cured film was cut into a strip 
of 100 mm in width to the extent that the plate was slightly flawed and 
then subjected to 180 degree peel test, in which one end of the strip was 
pulled by the aid of an autograph "IS-500" manufactured by Shimadzu Corp. 
at 24.degree. C. at a rate of 50.0.+-.2.5 mm/min. The results are shown in 
Table 5. 
TABLE 5 
______________________________________ 
3,9-Bis(3-amino- 
propyl)-2,4,8,10- 
tetraoxaspiro[5.5]- 
Tensile 
Peel 
A-1100 undecane strength 
strength 
Example (mol).sup.*1 
(mol).sup.*1 (kg/cm.sup.2) 
(kg/cm) 
______________________________________ 
15.sup.*2 
0.008 0.002 98 1.10 
(separated) 
16 0.006 0.004 117 0.50 
(separated) 
17 0.005 0.005 115 -- 
18 0.004 0.006 115 0.39 
(separated) 
19 0.002 0.008 115 0.32 
(separated) 
20.sup.*2 
0.01 0 48 1.50 
(separated) 
Compara- 
0 0.01 93 0.19 
tive 20 (separated) 
______________________________________ 
Notes: 
.sup.*1 Mol on the basis of 100 grams of the fluoroelastomer. 
.sup.*2 In Examples 15 and 20, the thickness of the film was about 350 
.mu.. 
EXAMPLE 21 AND COMATIVE EXAMPLE 21 
(Pot life and spray coating tests) 
In the same manner as in Example 10, Mixtures A, B and C having the 
following compositions were mixed together to make a water-based 
fluoroelastomer coating composition containing A-1100 and 
3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane respectively in 
amounts of 0.005 mol per 100 grams of the fluoroelastomer: 
______________________________________ 
Mixture A Parts 
______________________________________ 
Aqueous fluoroelastomer 
166 
dispersion (fluoroelastomer 
content, 60%; containing a 
non-ionic surfactant "Nissan 
Nonion HS 208") 
Magnesium oxide 3 
Medium thermal carbon 
20 
"Nissan Nonion HS 210" 
2 
Water 50 
______________________________________ 
Mixture B Parts 
______________________________________ 
A-1100 50 
Water 50 
______________________________________ 
Mixture C Parts 
______________________________________ 
3,6-Bis(3-aminopropyl)-2,4,8,10- 
50 
tetraoxaspiro[5.5]undecane 
Water 50 
______________________________________ 
For comparison, the following Mixtures A, B and C were mixed together to 
make a solvent type fluoroelastomer coating composition containing A-1100 
and 3,6-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane 
respectively in amounts of 0.005 mol per 100 grams of the fluoroelastomer: 
______________________________________ 
Mixture A Parts 
______________________________________ 
Fluoroelastomer 100 
Magnesium oxide 3 
Medium thermal carbon 
20 
Methyl ethyl ketone 225 
Methyl isobutyl ketone 
90 
______________________________________ 
Mixture B Parts 
______________________________________ 
A-1100 20 
n-Butanol 80 
______________________________________ 
Mixture C Parts 
______________________________________ 
3,6-Bis(3-aminopropyl)-2,4,8,10- 
50 
tetraoxaspiro[5.5]undecane 
n-Butanol 80 
______________________________________ 
The fluoroelastomer coating composition was charged into a volume glass 
bottle with a lid and allowed to stand at 24.degree. C. to test the pot 
life of the coating composition. In case of the water-based coating 
composition (Example 21), gelation of the solid components occurred after 
30 days, and it was impossible to redisperse the gel. In case of the 
solvent type coating composition (Comparative Example 21), gradual 
increase of viscosity was observed after about 4 hours, and the whole 
coating composition became gel after about 10 hours. 
The fluoroelastomer coating composition was spray-coated on an aluminum 
plate with a spray nozzle of 0.8 mm in diameter under a spray pressure of 
3.0 kg/cm.sup.2. In case of the solvent type coating composition 
(Comparative Example 21), cobwebbing occurred immediately after the start 
of spraying, but in case of the water-based coating composition (Example 
21), it could be sprayed without any trouble to form an even film.