A room temperature-curable organopolysiloxane composition with excellent extrudability and self-extinguishing properties is made from a hydroxyl endblocked polydiorganosiloxane, aluminum hydroxide having an average particle size not exceeding 50 micrometers, colloidal calcium carbonate, platinum or a platinum compound, and a crosslinking silane or siloxane having at least three hydrolyzable groups.

BACKGROUND OF THE INVENTION 
1. Technical Field 
The present invention relates to a room temperature-curable 
organopolysiloxane composition, and, more particularly, relates to a room 
temperature-curable organopolysiloxane composition which cures to give an 
excellent self-extinguishing silicone rubber. 
2. Prior Art and Problems to Be Solved by the Invention 
Room temperature-curable organopolysiloxane compositions exhibit a number 
of excellent properties, and as a consequence have entered into service in 
a variety of fields, for example, civil engineering, construction, general 
industry, and the electrical and electronics sectors. Nevertheless, these 
compositions generally suffer from the problem of poor 
self-extinguishability. There have been attempts at improving their 
self-extinguishability through the addition to the particular composition 
of large quantities of an extender filler such as crystalline silica, 
aluminum hydroxide, titanium dioxide, or carbon black, but each of these 
is associated with a poor workability. Specifically, the fatal drawback is 
poor extrudability from the container or cartridge. 
The present inventors carried out extensive research in order to solve the 
aforementioned drawbacks, and the present invention was developed as a 
result. 
In addition, when platinum or a platinum compound is also mixed into such 
compositions along with aluminum hydroxide in an attempt to improve the 
self-extinguishability, one finds that the self-extinguishability is still 
unsatisfactory. 
SUMMARY OF THE INVENTION 
An object of the present invention is a room temperature-curable 
organopolysiloxane composition which manifests an excellent pre-cure 
extrudability from containers and which cures to give an excellent 
self-extinguishing silicone rubber. 
Means Solving the Problems and Function Thereof 
The present invention relates to a room temperature-curable 
organopolysiloxane composition comprising (A) 100 parts by weight of 
hydroxyl group-terminated polydiorganosiloxane having a viscosity at 
25.degree. C. of 0.100 to 500 Pa.s (pascal-seconds), (B) 50 to 100 parts 
by weight of aluminum hydroxide microparticles having an average particle 
diameter not exceeding 50 micrometers, (C) 50 to 100 parts by weight of 
colloidal calcium carbonate, (D) platinum or a platinum compound, in a 
quantity sufficient to provide 1 to 200 parts by weight platinum metal per 
1,000,000 parts by weight component (A), and (E) 0.5 to 20 parts by weight 
of a silicon compound which contains at least 3 Si-bonded hydrolyzable 
groups in each molecule, where the silicon compound is a silane, siloxane, 
or mixture of silane and siloxane. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The polydiorganosiloxane comprising component (A) is the principal or base 
component of the composition according to the present invention. Its 
molecular terminals must be end-blocked by the hydroxyl group. This 
polydiorganosiloxane is exemplified by alpha, 
omega-dihydroxy-polydiorganosiloxanes with the following general formula. 
##STR1## 
In the preceding formula, each R is a substituted or an unsubstituted 
monovalent hydrocarbon group, and n is a number which provides 
polydiorganosiloxane viscosities of 0.1 to 500 Pa.s and preferably 0.5 to 
100 Pa.s at 25.degree. C. 
Examples of R are monovalent hydrocarbon groups as exemplified by alkyl 
groups such as methyl, ethyl, isopropyl, hexyl, and octadecyl; alkenyl 
groups such as vinyl and hexenyl; cycloalkyl groups such as cyclohexyl and 
cyclopentyl; alkaryl groups such as benzyl and beta-phenylethyl; and 
aromatic hydrocarbon groups such as phenyl, xenyl, naphthyl, tolyl, and 
xylyl. R may also be those substituted hydrocarbon groups obtained by 
replacing hydrogen in the aforesaid monovalent hydrocarbon groups with a 
cyano group or halogen such as beta-cyanoethyl, 1,1,1-trifluoropropyl, or 
perfluorobutyl. R may consist of only a single species within the 
individual molecule, or a combination of several species may be present in 
each molecule. Taking into consideration ease of synthesis and the balance 
between the viscosity of the uncured composition and the post-cure 
mechanical properties, it will be preferred within the context of the 
present invention that methyl comprise much or all of the groups R, with 
vinyl or phenyl accounting for any remaining groups R. The composition 
according to the present invention has a reduced extrudability when the 
viscosity exceeds 500 Pa.s. On the other hand, when the viscosity falls 
below 0.1 Pa.s, the elasticity or extensibility of the cured rubber is so 
low that it cannot tolerate in practical applications. 
The aluminum hydroxide micropowder of component (B) of the present 
invention is an essential component for imparting self-extinguishability 
to the composition. The average particle size of component (B) must not 
exceed 50 micrometers: when the average particle size exceeds 50 
micrometers, the self-extinguishability deteriorates and/or the post-cure 
rubber properties are impaired. Preferably, the average particle size is 
less than 10 micrometers. 
Aluminum hydroxide should be added at 50 to 100 parts by weight per 100 
parts by weight of component (A). The self-extinguishability is impaired 
at less than 50 parts by weight while the extrudability is impaired at 
additions in excess of 100 parts by weight. 
The colloidal calcium carbonate of component (C) is an essential component 
for simultaneously equipping the composition according to the present 
invention with self-extinguishability, suitable rubber properties, and a 
good extrudability. 
As is known in the concerned art, calcium carbonate is available as heavy 
calcium carbonate, light calcium carbonate, and colloidal calcium 
carbonate; however, the composition according to the present invention can 
make use of only colloidal calcium carbonate, which has the smallest 
particle size among these grades. The invention does not require that the 
surface of the calcium carbonate be either treated or untreated, but 
treatment with, for example, an aliphatic acid, resin acid, or surfactant, 
is preferred. Preferably, the average particle size is less than one 
micrometer. 
Component (C) should be added at 50 to 100 parts by weight per 100 parts by 
weight of component (A). The self-extinguishability and rubber properties 
are impaired at less than 50 parts by weight, while the extrudability is 
compromised at more than 100 parts by weight. 
The platinum or platinum compound of component (D) is an essential 
component for imparting self-extinguishability. It should be added at 1 to 
200 parts by weight as platinum metal and preferably at 10 to 100 parts by 
weight as platinum metal per one million parts by weight component (A). 
Self-extinguishability is not manifested at less than 1 parts by weight, 
while exceeding 200 parts by weight is uneconomical because doing so does 
not result in further improvement in the self-extinguishability. Component 
(D) is exemplified by platinum micropowders; platinum powder supported on 
a carrier such as alumina, silica gel, or asbestos; chloroplatinic acid; 
and complexes between chloroplatinic acid and alcohols, ethers, aldehydes, 
or vinylsiloxanes. 
To support its dispersion in the composition, the platinum or platinum 
compound should be used dissolved or dispersed in organopolysiloxane oil 
or an organic solvent such as isopropanol, ethanol, benzene, toluene, or 
xylene. 
Component (E) of the present invention functions as crosslinker for the 
composition. Component (E) is a silicon compound containing at least 3 
Si-bonded hydrolyzable groups in each molecule. The hydrolyzable groups 
are selected from the group consisting of alkoxy, haloalkoxy, 
alkoxyalkoxy, alkenyloxy, ketoximo, amino, acetamido, and aminoxy. 
This silicon compound can be a silane, a siloxane, or a mixture of a silane 
and a siloxane is exemplified as follows: alkoxysilanes such as 
tetraethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, 
vinyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 
beta-cyanoethyltrimethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, 
phenyltrimethoxysilane, and octadecyltrimethoxysilane; 
halogenoalkoxysilanes such as tetra(beta-chloroethoxy)silane, 
tetra(2,2,2-trifluoroethoxy)silane, and 
propyltris(delta-chlorobutoxy)silane; alkoxyalkoxysilanes such as 
methyltris(methoxyethoxy)silane; alkoxysiloxanes such as ethyl 
polysilicate and dimethyltetramethoxydisiloxane; ketoximosilanes such as 
methyltris(methyl ethyl ketoximo)silane, vinyltris(methyl ethyl 
ketoximo)-silane, phenyltris(methyl ethyl ketoximo)silane, 
methyltris-(diethyl ketoximo)silane, and tetra(methyl ethyl 
ketoximo)-silane; aminosilanes such as methyltris(cyclohexylamino)silane, 
and vinyltris(n-butylamino)silane; acetamidosilanes such as 
methyltris(N-methylacetamido)silane, methyltris(N-butylacetamido)silane, 
methyltris(N-cyclohexylacetamido)silane; aminoxysilanes such as 
methyltris(N,N-diethylaminoxy)silane; alkenyloxysilanes such as 
methyltri(isopropenoxy)silane and vinyltri(isopropenoxy)silane; and 
aminoxysiloxanes such as 
##STR2## 
These silanes and siloxanes should be added with the range of 0.5 to 20 
parts by weight per 100 parts by weight component (A). The specific 
quantity of component (E) should be optimally selected in accordance with, 
for example, the quantity of water in the composition and whether the 
composition of the present invention is to be formulated in a 
single-package or two-package configuration. 
The composition according to the present invention may also contain as 
chain extenders, on a supplementary basis, difunctional silane and/or 
difunctional siloxane for the purpose of increasing the elongated or 
extensibility and reducing the modulus. These difunctional silanes and 
siloxanes have two hydrolyzable groups per molecule. 
The aforesaid difunctional silanes and siloxanes are exemplified as 
follows: dimethylbis(N-methylacetamido)silane, 
dimethylbis(N-ethylacetamido)silane, diphenylbis(diethylaminoxy)silane, 
methylphenylbis(diethylaminoxy)silane, diphenyldimethoxysilane, and 
siloxanes as follows: 
##STR3## 
Furthermore, the composition according to the present invention may 
optionally contain a catalyst in order to accelerate the cure between 
components (A) and (E). Suitable catalysts are exemplified by the metal 
salts of monocarboxylic acids such as lead 2-ethyloctoate, dibutyltin 
diacetate, dibutyltin 2-ethylhexoate, dibutyltin dilaurate, butyltin 
tri-2-ethylhexoate, dibutyltin acetylacetonate, iron 2-ethylhexoate, 
cobalt 2-ethylhexoate, manganese 2-ethylhexoate, stannous caprylate, tin 
naphthenate, tin oleate, tin butyrate, zinc naphthenate, zinc stearate, 
and titanium naphthenate; titanate catalyst such as tetrabutyl titanate, 
tetraphenyl titanate, tetra-2-ethylhexyl titanate, tetraoctadecyl 
titanate, triethanolamine titanate, and ethylene glycol titanate; the 
organosiloxytitanium compounds disclosed in U.S. Pat. No. 3,294,739, in 
which the organosiloxy group is bonded to the titanium atom via Si--O--Ti; 
the beta-dicarbonyltitanium compounds disclosed in U.S. Pat. No. 3,334,067 
with the following general formula 
##STR4## 
wherein R.sup.1, R.sup.2, and R.sup.3 are monovalent hydrocarbon groups 
having 1 to 18 carbon atoms; Z is a group selected from the group 
consisting of monovalent aliphatic hydrocarbon groups, monovalent acyloxy 
groups, the hydroxyl group, and the divalent oxygen atom participating in 
the Ti--O--Ti bond; amines such as hexylamine and dodecylamine; amine 
salts such as hexylamine acetate and dodecylamine phosphate; quaternary 
ammonium salts such as benzyltrimethylammonium acetate; and alkali metal 
salts such as potassium acetate. The catalyst is added at 0.001 to 10 
parts by weight and preferably at 0.01 to 5 parts by weight, in each case 
per 100 parts by weight component (A). 
The composition according to the present invention is prepared simply by 
mixing components (A), (B), (C), (D), and (E) together along with the 
optional cure-accelerating catalyst as described above. Those additives 
known in the art for use in room temperature-curable organopolysiloxane 
compositions may be admixed on an optional basis within the scope of the 
present invention, as long as, the object of the present invention is not 
compromised thereby. Examples in this regard are the various organic 
solvents, low-molecular-weight organopolysiloxanes, fillers and pigments 
(e.g., magnesium oxide, alumina, zinc oxide, iron oxide), flame retardants 
such as manganese carbonate and azobisisobutyronitrile, heat stabilizers 
such as cerium hydroxide and cerium oxide, and adhesion promoters such as 
silane coupling agents.

The present invention will be explained in greater detail through the 
following illustrative examples, in which parts=parts by weight and the 
viscosity is the value at 25.degree. C. The various properties considered 
below were measured using the following test methods. 
Extrudability 
The particular room temperature-curable organopolysiloxane composition was 
filled into a 2 mL syringe. The time required for extrusion (extrusion 
pressure=2 kg/cm.sup.2) of the total quantity was then measured and is 
reported in seconds. 
Rubber Properties 
The particular room temperature-curable organopolysiloxane composition was 
cured at room temperature for 7 days to give a 3 mm-thick silicone rubber 
sheet. The physical properties (hardness, tensile strength, elongation) of 
the silicone rubber sheet thus obtained were measured in accordance with 
the methods in JIS K 6301. 
Measurement of Self-Extinguishability 
This property was measured in accordance with the flame retardancy test 
method of UL 94V. First, the particular room temperature-curable 
organopolysiloxane composition was cured to give a 0.8 mm-thick silicone 
rubber sheet. This sheet was then cut into a test specimen with a length 
of 127 mm and a width of 12.7 mm. The test specimen was hung vertically 
under draft-free conditions, and the bottom of the test specimen was 
exposed twice (10 seconds each) to the flame from a 1,000 BTU/ft.sup.3 gas 
burner. The time (seconds) required for extinction of the flame was 
measured in each case. This double flame contact test was conducted on 
each of 5 test specimens, and the total value of the 10 observations was 
reported as the self-extinguishability (unit: seconds). The char length 
was observed and reported as less than 20 mm, greater than 20 mm, or 
completely consumed (127 mm). 
EXAMPLE 1 
The following were mixed at room temperature and in the sequence given into 
100 parts alpha, omega-dihydroxypolydimethylsiloxane (viscosity=13 Pa.s): 
100 parts aluminum hydroxide micropowder with an average particle size of 
1.0 micrometers, 50 parts colloidal calcium carbonate (average particle 
size=0.08 micrometers) whose surface had been treated with fatty acid, and 
isopropanolic chloroplatinic acid solution sufficient to give 22 ppm 
platinum metal. The resulting mixture was then mixed in vacuo to 
homogeneity. 
A room temperature-curable organopolysiloxane composition was then prepared 
by mixing to homogeneity under moisture free conditions 100 parts of the 
mixture obtained as above: 4.0 parts vinyltris(methyl ethyl 
ketoxime)silane, 0.5 part 
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, and 0.04 part 
dibutyltin dilaurate. The resulting room temperature-curable 
organopolysiloxane composition was sealed into aluminum tubes. 
The compositions's extrudability, fluidity, post-cure rubber properties 
(hardness, tensile strength, and elongation), and flame retardancy were 
then measured, and these results are reported in Table 1. 
TABLE 1 
______________________________________ 
ITEM MEASURED VALUE 
______________________________________ 
Extrudability (seconds) 
68 
Fluidity not fluid 
Hardness (JIS A) 65 
Tensile strength (kg/cm2) 
30 
Elongation (%) 175 
Flame retardancy (seconds) 
19 
Char length, mm &lt;20 
______________________________________ 
EXAMPLE 2 
The following were mixed at room temperature and in the sequence given into 
100 parts alpha, omega-dihydroxypolydimethylsiloxane (viscosity=12 Pa.s): 
70 parts aluminum hydroxide micropowder with an average particle size of 
1.0 micrometers, 70 parts colloidal calcium carbonate (average particle 
size=0.08 micrometers) whose surface had been treated with fatty acid, and 
isopropanolic chloroplatinic acid solution sufficient to give 22 ppm 
platinum metal. The resulting mixture was then mixed in vacuo to 
homogeneity. A room temperature-curable organopolysiloxane composition was 
prepared by mixing to homogeneity under moisture free conditions 100 parts 
of the mixture obtained above, 4.0 parts vinyltris(methyl ethyl 
ketoxime)silane, 0.5 part 
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, and 0.04 part 
dibutyltin dilaurate. The resulting room temperature-curable 
organopolysiloxane composition was sealed into aluminum tubes. The 
compositions's extrudability, post-cure rubber properties, and flame 
retardancy were then measured, and these results are reported in Table 2. 
COMISON EXAMPLE 1 
A room temperature-curable organopolysiloxane composition was prepared as 
in Example 2, except omitting the colloidal calcium carbonate and 
increasing the quantity of aluminum hydroxide micropowder to 100 parts. 
The various properties of this composition were also measured as in 
Example 2, and these results are reported in Table 2. 
COMISON EXAMPLE 2 
A room temperature-curable organopolysiloxane composition was prepared as 
in Example 2, except omitting the colloidal calcium carbonate and 
increasing the quantity of aluminum hydroxide micropowder to 150 parts. 
The extrudability, post-cure rubber properties, and flame retardancy of 
the resulting composition were measured as in Example 2, and these results 
are reported in Table 2. 
COMISON EXAMPLE 3 
A room temperature-curable organopolysiloxane composition was prepared as 
in Example 2, except a precipitated calcium carbonate with an average 
particle size of 2.2 micrometers was used in place of the colloidal 
calcium carbonate employed in Example 2. The various properties of the 
composition thus obtained were measured as in Example 2, and these results 
are reported in Table 2. 
COMISON EXAMPLE 4 
A room temperature-curable organopolysiloxane composition was prepared as 
in Example 2, except a heavy calcium carbonate with an average particle 
size of 3.6 micrometers was used in place of the colloidal calcium 
carbonate employed in Example 2. The various properties of the composition 
thus obtained were measured as in Example 2, and these results are 
reported in Table 2. 
COMISON EXAMPLE 5 
A room temperature-curable organopolysiloxane composition was prepared as 
in Example 2, except 7 parts of a dry-method silica (specific surface area 
by the BET method=200 m.sup.2 /g) was used in place of the colloidal 
calcium carbonate employed in Example 2. The various properties of the 
composition thus obtained were measured as in Example 2, and these results 
are reported in Table 2. 
COMISON EXAMPLE 6 
A room temperature-curable organopolysiloxane composition was prepared as 
in Example 2, except the aluminum hydroxide was omitted and the amount of 
colloidal calcium carbonate was increased to 140 parts. The various 
properties of this composition were measured as described in Example 2, 
and these results are reported in Table 2. 
TABLE 2 
______________________________________ 
PRESENT COMISON EXAMPLES 
INVENTION 1 2 3 4 5 6 
______________________________________ 
Extrudability 
57 40 114 68 68 115 50 
(seconds) 
Fluidity 
++ x ++ + x + ++ 
Hardness 
55 33 63 52 46 20 61 
(JIS A) 
Tensile 23 19 25 25 27 20 26 
Strength 
(kg/cm2) 
Elongation 
250 320 170 200 220 450 230 
(%) 
Flame 25 ** 7 59 50 170 ** 
Retardancy 
(seconds) 
Char length 
&lt;20 127 &gt;20 &gt;20 &gt;20 &gt;20 127 
(mm) 
______________________________________ 
++ = completely combusted 
++ = not fluid 
+ = semifluid 
x = fluid 
EXAMPLE 3 
The following were mixed at room temperature and in the sequence given into 
100 parts alpha, omega-dihydroxypolydimethylsiloxane (viscosity=13 Pa.s): 
80 parts aluminum hydroxide micropowder with an average particle size of 
1.0 micrometers, 50 parts colloidal calcium carbonate (average particle 
size=0.08 micrometers) whose surface had been treated with fatty acid, and 
isopropanolic chloroplatinic acid solution sufficient to give 22 ppm 
platinum metal. This mixture was then mixed in vacuo to homogeneity. A 
room temperature-curable organopolysiloxane composition was then prepared 
by mixing to homogeneity under moisture free conditions 100 parts of the 
mixture obtained above, 4.0 parts methyltrimethoxysilane and 1.0 part 
diisopropoxybis(ethyl acetoacetate)titanium. The resulting room 
temperature-curable organopolysiloxane composition was sealed into 
aluminum tubes. The composition's extrudability, post-cure rubber 
properties, and flame retardancy were then measured, and these results are 
reported in Table 3. 
TABLE 3 
______________________________________ 
ITEM MEASURED VALUE 
______________________________________ 
Extrudability (seconds) 
70 
Fluidity not fluid 
Hardness (JIS A) 61 
Tensile strength (kg/cm2) 
32 
Elongation (%) 150 
Flame retardancy (seconds) 
12 
Char length, (mm) 
&lt;20 
______________________________________ 
EXAMPLE 4 
The following were mixed at room temperature and in the sequence given into 
100 parts alpha, omega-dihydroxypolydimethylsiloxane (viscosity=13 Pa.s): 
70 parts aluminum hydroxide micropowder with an average particle size of 
1.0 micrometers, 70 parts colloidal calcium carbonate (average particle 
size=0.08 micrometers) whose surface had been treated with fatty acid, and 
isopropanolic chloroplatinic acid solution sufficient to give 22 ppm 
platinum metal. This mixture was then mixed in vacuo to homogeneity. A 
room temperature-curable organopolysiloxane composition was prepared by 
mixing to homogeneity under moisture free conditions 100 parts of the 
mixture obtained above, 1.2 parts of the following compound 
##STR5## 
and 3.3 parts dimethylbis(N-ethylacetamide)silane. The resulting room 
temperature-curable organopolysiloxane composition was sealed into 
aluminum tubes. The composition's extrudability, post-cure rubber 
properties, and flame retardancy were then measured, and these results are 
reported in Table 4. 
TABLE 4 
______________________________________ 
ITEM MEASURED VALUE 
______________________________________ 
Extrudability (seconds) 
54 
Fluidity not fluid 
Hardness (JIS A) 5 
Tensile strength (kg/cm2) 
4 
Elongation (%) 1400 
Flame retardancy (seconds) 
19 
Char length, (mm) 
&lt;20 
______________________________________ 
EXAMPLE 5 
The following were mixed at room temperature and in the sequence given into 
100 parts alpha, omega-dihydroxypolydimethylsiloxane (viscosity=13 Pa.s): 
70 parts aluminum hydroxide micropowder with an average particle size of 
1.0 micrometers, 70 parts colloidal calcium carbonate (average particle 
size=0.08 micrometers) whose surface had been treated with fatty acid, and 
isopropanolic chloroplatinic acid solution sufficient to give 22 ppm 
platinum metal. This mixture was then mixed in vacuo to homogeneity. A 
room temperature-curable organopolysiloxane composition was prepared by 
mixing to homogeneity under moisture free conditions 100 parts of the 
mixture obtained above, 0.1 part of the following compound 
##STR6## 
and 2.4 parts of the following compound 
##STR7## 
The composition's extrudability, post-cure rubber properties, and flame 
retardancy were then measured, and these results are reported in Table 5. 
TABLE 5 
______________________________________ 
ITEM MEASURED VALUE 
______________________________________ 
Extrudability (seconds) 
-- 
Fluidity not fluid 
Hardness (JIS A) 18 
Tensile strength (kg/cm2) 
12 
Elongation (%) 1500 
Flame retardancy (seconds) 
30 
Char length, (mm) 
&lt;20 
______________________________________ 
EXAMPLE 6 
The following were mixed at room temperature and in the sequence given into 
100 parts alpha, omega-dihydroxypolydimethylsiloxane (viscosity=12 Pa.s): 
50 parts colloidal calcium carbonate (average particle size=0.08 
micrometers) whose surface had been treated with fatty acid: 100 parts 
aluminum hydroxide micro powder with an average particle size of 1.0 
micrometers and isopropanolic chloroplatinic acid solution sufficient to 
give 22 ppm platinum metal. The resulting mixture was then mixed in vacuo 
to homogeneity. A room temperature-curable organopolysiloxane composition 
was prepared by mixing to homogeneity under moisture free conditions 100 
parts of the mixture obtained as above: 4.0 parts vinyltri(methyl ethyl 
ketoxime)silane, 0.5 part 
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, and 0.04 part 
dibutyltin dilaurate. The resulting room temperature-curable 
organopolysiloxane was sealed into aluminum tubes. 
The compositions's extrudability, fluidability, post-cure rubber properties 
(hardness, tensile strength and elongation), and flame retardancy were 
measured, and these results were as reported in Table 6. 
COMISON EXAMPLE 7 
A room temperature-curable organopolysiloxane composition was prepared as 
in Example 6, except decreasing the quantity of the colloidal calcium 
carbonate to 20 parts. Then composition's properties were measured and 
were as reported in Table 6. 
COMISON EXAMPLE 8 
A room temperature-curable organopolysiloxane composition was prepared as 
in Example 6, except increasing the quantity of the colloidal calcium 
carbonate to 120 parts. The composition's properties were measured and 
were as reported in Table 6. 
TABLE 6 
______________________________________ 
COMISON COMISON 
EXAMPLE 7 EXAMPLE 6 EXAMPLE 8 
______________________________________ 
Composition 
Colloidal Calcium 
20 50 120 
Carbonate (parts) 
Aluminum 100 100 100 
Hydroxide 
Micro Powder 
(parts) 
Properties 
Extrudability 
42 57 147 
(seconds) 
Fluidability 
flowable not fluid not fluid 
(non-sag) (non-sag) 
Flame Retardance 
50 26 25 
(seconds) 
Hardness (JIS-A) 
32 40 50 
Tensile Strength 
15 12 20 
(kg/cm2) 
Elongation (%) 
350 300 270 
______________________________________ 
Comparison Example 6 with 20 parts of the colloidal calcium carbonate 
resulted in a flowable composition with poorer flame retardant properties 
whereas increasing the colloidal calcium carbonate to 120 parts, the 
composition had satisfactory flame retardant properties but the 
extrudability was poor. 
EXAMPLES 7-10 
The following were mixed at room temperature and in the sequence given into 
100 parts alpha, omega-dihydroxypolydimethylsiloxane (viscosity=12 Pa.s): 
5.0 methyltris (methyl ethyl ketoxime) silane as a filler treatment agent: 
50-100 parts colloidal calcium carbonate (average particle size=0.08 
micrometers) whose surface had been treated with fatty acid: 50-100 parts 
aluminum hydroxide micro powder with an average particle size of 1.0 
micrometers as shown in Table 7 and chloroplatinic acid isopropyl alcohol 
solution sufficient to give 22 ppm platinum metal. The resulting mixture 
was then mixed in vacuo to homogeneity. The specific amounts of colloidal 
calcium carbonate and aluminum hydroxide micro powder used in each example 
was as shown in Table 7. 
A room temperature-curable organopolysiloxane composition was then prepared 
by mixing to homogeneity under moisture free conditions 100 parts of the 
mixture obtained as above: 5.0 parts vinyl tris (methyl ethyl ketoxime) 
silane, 1.25 parts N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, 
and 0.16 part dibutyltin dilaurate. The resulting room temperature-curable 
organopolysiloxane was sealed into aluminum tubes. 
The composition extrudability, fluidability, post-cure rubber properties 
(hardness, tensile strength and elongation), and flame retardancy were 
measured, and these results were as shown in Table 7. 
TABLE 7 
______________________________________ 
Example 7 
Example 8 
Example 9 
Example 10 
______________________________________ 
Composition 
Aluminum Hydroxide 
50 100 50 100 
micro powder 
(part) 
Colloidal calcium 
50 50 100 100 
carbonate (part) 
Properties 
Extrudability 
27 52 57 72 
(seconds) 
Fluidability 
not fluid 
not fluid 
not fluid 
not fluid 
(non-sag) 
(non-sag) 
(non-sag) 
(non-sag) 
Flame retardancy 
73 52 26 10 
Hardness (JIS-A) 
23 40 37 48 
Tensile Strength 
13 12 14 16 
(kg/cm2) 
Elongation (%) 
450 300 300 280 
______________________________________ 
Effects of the Invention 
Because the room temperature-curable organopolysiloxane composition 
according to the present invention is composed of components (A) through 
(E), and in particular because it contains the quantities of specific 
components of (B), (C), and (D), it is characterized both by an excellent 
extrudability from containers prior to its cure and by the ability to cure 
into an excellent self-extinguishing silicone rubber.