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Патент USA US3086964

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Uni-ted States Patent‘: 0
1
31,086,954
,.
1C6
Patented Apr. 23, 1963
2
.
V
.
said organosilicon polymers having a silicon'bonded OH
content of - at least 20H per ‘molecule and-having an
‘
'
'
3,086,954
'-
‘
'
average of from 1.95 to 2.05 monovalent organic groups
attached to silicon pe'r silicon atom and having an average
CYANOGUANIDWE AS A VULCANIZATION
AGENT FOR SILICONE RUBBER,
_
Keith E. Polmanteer, Midland, and Virgil L. Metevia, 5 of at least 400 silicon atoms. per molecule, .
Bay City, Mich., assignors to vDow Corning Corpora
(2) At least 10 percent by weight based on the weight
tion, Midland, Mich., a c'orporati'onof Michigan
(l) ‘of a modi?ed silica‘ ?ller comprising ?nely
No Drawing. Filed Aug.‘17, 1961, Ser. No. 131,987
divided
hydrophobic solid particles having a surface
19 Claims. (til. 260-37)
' area of vat least 100>m.2/g., each of said particles con
~ vsisting essentially of a polymeric siliceous substrate
This invention relates to the art of using cyano
guanidine as a vulcanizing agent for certain silicone
elastomers.
-
l
-
-
‘-
consisting essentially of
- >
-
(A) From 50 to 100 inclusive mol percent of units
-»
tear strengths were required, silicone rubber could not be
used, even though‘ a rubber possessing a thermal stability 20
of silicone rubber was needed. Forrexample, the poor
tear strength of silicone rubber has precluded its use in
of the formula Si-O‘2,‘and
(B) From 0’ to 50 inclusive mol percent of units
of the formula RSiOL5, wherein ‘R is selected from
the ‘group consisting of alkyl radicals of less than
6 carbon atoms and phenyl, there being
(C) Organosilyl units selected from the group con—
sisting of R’R”Si= and R'2R"Si-~, wherein R’ is
selected from the group~consisting of alkyl radi
cals of less than 6 carbon atoms and phenyl, and
R” is selected from the group consisting of alkyl
high speed airplane tires.
' radicals of~less than 6 carbon atoms, 3,3,3-tri
> Silicone rubber is now a well-known article of com
merce. > It- is available in a wide variety of different types
and has been prepared vfrom a host of different organo-. 15
siloxane polymers or copolymers with various ?llers and
curing catalysts. Inrthe past, however, even the best of
the silicone rubbers had poor tear strengths. When high
-
-
'?uor'opro‘pyl‘and phenyl radicals, in an amount
In the past, two di?iculties have been encountered in
the peroxide vulcanization of‘ silicone rubber. One of 25
‘ such that the molar ratio of‘ (C) units to total
these di?'iculties has been the poor vulcanization obtained
in the center of thick sections (e.g., one inch sections)
of silicone rubber. This resulted in a ?nished rubber
' ‘ organosilyl units ‘being attached to silicon atoms
part having varying physicalsproperties throughout the
part. For example, the durometer and‘ tensile strength
would be much lower in the center of the part than near
the surface. ‘In some instances, the interior of very
thick samples would be completely unvulcanized. . ‘It has
been theorized that this, was due primarily to the chemi
cal action oftthe decomposition products of the peroxide.
(A)»and (B) units is not in excess of 0.6, said
in the surface of said substrate through SiOSi
‘
~ linkages, and
-
.
a
(3) At least 0.1 percent-‘by weight based on the weight
of (1) of cyanoguanidine.
This invention is also particularly concerned with the
rubber which is obtained when the above-described heat
curable composition of matter is “cured” or “vulcanized.”
This =composition can be cured by heating, preferably
in the range of 160° to 200° C. ‘for 10 to 15 minutes.
The second di?iculty is that oxygen inhibition occurs
when peroxide is used to vulcanize silicone rubber in the
presence of oxygen. For exaniple,peroxide vulcaniza
The terms “rubber stock” and “heat curable composi
ject to provide a method whereby deep sections of sili
each of the polymer molecules. The organosilicon poly
tion of matter” are used to refer to the uncured mixture
tion of silicone rubber in an air-oven at 150° C. will 40 from which the ?nal rubbery ‘product can be obtained.
The organosilicon polymers that can be used herein
result in a vulcanized interior‘ while the surface will not
must contain :at least 2 OH per molecule. The polymers
'be vulcanized at all. This results in a poor product.
can be end-blocked with hydroxyl groups or these groups
It is an object of the present invention to provide an
can bebonded to non-terminal silicon atoms in the poly
improved silicone rubber, and particularly to provide a
rubber with improved tear strength. It is a further ob 45 ‘mer. Preferably the hydroxyl groups are on each end of
cone rubber stock can be vulcanized so that uniform
properties are obtained throughout the section.
It is a
mers that can be used must have an ‘average of at least
1 400'silicon atoms per molecule. Thus, the polymers can
‘further object to obviate the necessity of excluding air
be ‘liquids or non?owing benzene-soluble ‘gums. The par
Another ob 50 ticular physical state of the polymer will vary, depending
ject is to provide a silicone rubber with very high tensile
upon the end use of the elastomer. For instance, ?uid
while vulcanizing a silicone rubber stock.
polymers are prepared for such applications as coating
strengths.
it has been found that these objects can be obtained
by a heat-curable composition of matter consisting es
> and potting.
On the other'ha'nd, when excellent tensile
and tear strengths are desired, high molecular weight non
55 ?owing‘solu-ble gums are preferable.
sentially of
(1) Hydroxylated organosilicon polymers selected from
the group consisting of
- 1
I
(A) Organopolysiloxanes in which the organic
groups are selected from the group consisting of
There must be an
average of from 1.95 to 2.05 monovalent organic groups
attached to silicon per silicon atom. The organosilicon
> polymer can contain relatively minor amounts of mono
organo or triorganosilyl units.
Such units can only be
monovalent hydrocarbon radicals and halogenated 60 present in relatively minor amounts so that the average
degree of substitution of-from 1.95 to 2.05 org-ano radi
monovalent hydrocarbon radicals, and
cals per silicon atom is‘ maintained.
(B) Polymers containing units of the structure
‘ Any conventional hydroxyl containing organopoly
siloxane can'be usediin this invention. The organic
Y Y
VS‘iXE‘ii-O
-
_
>
i
Y
_
65 groups attached to the silicon atoms can be any mono
-
,
wherein X is a ‘divalent radical composed of‘car
bon and. hydrogen atoms and no more than one
valent hydrocarbon‘ radical; Speci?c examples of these
groups which are operative in this invention are alkyl
groups; such as methyl, ethyl, tert-butyl and octadecyl;
alkenylvgroups such as vinyl, allyl and butadienyl; cyclo
70 alkyl groups such as cyclobutyl, cyclopentyl and cyclo
hexyl; cycloalkenyl groups such as cyclopentenyl and
I
‘I
cyclohexenyl; aryl groups such as phenyl and xenyl; aral
group and Y is a monovalent hydrocarbon radical,
oxygen atom, said oxygen atom being present in a
_<B_O_é_
3,086,954
4
kyl groups, such as benzyl and xylyl and alkaryl groups
such as tolyl.
SiOz units or they can be composed of from 50 to 100
mol percent of SiOz and 0 to 50 mol percent RSiOL5,
wherein R is an alkyl radical of less than 6 carbon atoms
The organic group can also be any of
the above types of radicals with halogen atoms attached
thereto, e.>g., chloromethyl, bromophenyl, tri?uorotolyl,
or phenyl. Thus, R can be methyl, ethyl, propyl, butyl
CF3CH2CH2 and C3F7CH2CH2. These polysiloxanes are
well known materials.
The siloxane can be a homopolymer (i.e., containing
or pentyl radicals. If RSiO1_5 units are present, these
?llers are commonly called cogels. The methods of mak
ing these cogels are well known in the art.
Organosilyl units are chemically bonded to silicon
atoms in the surface of the substrate through SiOSi link
only one species of siloxane unit), or a copolymer con
taining two or more different species of siloxane units.
The siloxane can also be a mixture of any combination 10 ages. These organosilyl units can be either R”R’Si= or
of homopolymers and/or copolymers. In the siloxane,
R’2R"Si~—. R’ and R" can be any alkyl radical of less
either one or different types of organic groups can be
than ‘6 carbon atoms or phenyl. Thus, R’ and R” can
attached to each silicon atom. Although homopolymers,
be methyl, ethyl, propyl, or butyl. The silica ?ller can
such as hydroxyl endblocked phenylmethylpolysiloxane,
be coated with diorganosilyl, triorganosilyl groups or mix
can be used in this invention, it is preferred that the 15 tures of such groups with or without limited amounts of
organopolysiloxane contain at least 75 mol percent of
monoorganosilyl groups. The organosilyl unit can also
units of the formula (CH3)2SiO with the remaining units
contain one 3,-3.3-tri?uoropropyl group per silicon atom.
being any of the following:
Speci?c examples of organosilyl groups which can be
attached to the surface of the silica through SiOSi link
(csHs) asio
and
ages are dimethylsilyl, trimethylsilyl, dimethylphenylsilyl,
(F3CCH2CH2) ( CH3 ) S10
(CH3 )‘(CH2=CH) SK)
3,3,3-tri?uoropropyldimethylsilyl, dimethylbutylsilyl and
triethylsilyl.
The ratio of organosilyl units to total SiOz and RSiO1_5
(cs'Hs) (CH3 ) Sio
units is 0.6 or less. Best results are obtained when the
Such hydroxylated siloxane can be prepared by any 25 surface of the substrate is saturated with organosilyl units.
convenient method ‘for preparing such siloxanes. These
The term “saturate” means that essentially all the reactive
include heating cyclic siloxanes with steam under pres~
sites (presumably SiOH groups) on the surface of the
sure and the careful hydrolysis of alkoxysilanes under
silica substrate have been covered with organosilyl groups.
relatively neutral conditions. Another method is that of
The precise amount of organosilyl groups needed to “sat
preparing the corresponding chlorosilanes ‘and then hy 30 urate” the surface of the substrate will depend on the type
drolyzing the chlorine.
of ?ller, surface area of the ?ller, type of treatment of
The organosilicon polymer can also be a polymer
the ?ller, ‘and numerous other factors. Depending on
containing units of the structure
the above factors, the surface of the ?ller can be saturated
at a value below 0.6. Although preferable, it is not es
35 sential that the surface be saturated with organosilyl
groups. However, it is necessary that there be at least
‘a few organosilyl units chemically bonded to the surface
Y Y
wherein X is a divalent radical composed of carbon and
' of the filler. These ?llers can be prepared by any suita
hydrogen atoms and no more than one oxygen atom, said
ble method. Methods of preparing satisfactory ?llers
40
oxygen atom being present in a
are disclosed in U.S. Patent 2,863,846 of Leslie J. Tyler
and his copending application 460,773 ?led October 6,
_
1954.
One suitable method is to prepare a ?nely divided silica
group and Y is a monovalent hydrocarbon radical. Spe
such as one may obtain by burning a volatile silane, and
ci?c examples of such monovalent hydrocarbon radicals
thereafter treat the silica with a reactive organosilicon
are listed in the description of the polysiloxanes. As 45 compound which will provide the speci?ed range and
mentioned earlier, there must be from 1.95 to 2.05 mono
valent organic groups (in this case Y units) attached to
silicon per silicon atom.
kinds of organosilyl units attached to the surface of the
silica substrate.
Chlorosilanes, silanols, and alkoxy
silanes, which will provide the proper kinds of organo
Speci?c examples of X are methylene, ethylene, p 50 silyl units, can be used to treat the substrate.
phenylene, 4,4-diphenylene, p-xylylene, 4,4'-diphenylene
A second method is that of reacting a silica hydrogel
ether, and 4,4'-dimethylenediphenyl ether. These poly
mers can be homopolymers (i.e., the polymer only con
tains the above silcarbane units), or the polymers can be
or organogel with the proper reactive organosilicon com
pounds.
In general, this method entails precipitating
silica from an alkali metal silicate solution to form a
block copolymers containing both .blocks of the above 55 silica hydrogel and thereafter treating the gel with a re
units and [blocks of the previously de?ned siloxane units.
active organosilane or organosiloxane compound such
Silarylenesiloxane block copolymers are disclosed in co
as a chlorosilane, silanol, alkoxysilane or a siloxane.
pending application No. 51,594, ?led August 24, 1960.
When a siloxane is employed, treatment should be carried
These polymers yield ‘elastomers with unusually high
out under acidic conditions which insure complete re
tensile strengths.
60 action of the organosilicon compound with the silica.
The surface area of the filler is quite critical and must
be at least 100 square meters per gram as measured by
nitrogen adsorption with the method described in \ASTM
Special Technical Bulletin No. 51, page 95 et seq. (1941).
A third method is that of treating a silica hydrogel or
a mixture of a hydrogel and aerogel with isopropanol and
a siloxane until the water in the gel is replaced by the
siloxane. The water is then separated and the alcohol
A satisfactory elastomer is not obtained if ?llers below 65 and excess siloxane are removed from the gel.
100 square meters per gram are used. The preferred
surface area is between 7300 and 400 square meters per
gram. There is no critical maximum for the silica sur
At least 10 parts by weight of ?ller per 100 parts of
organosilicon polymer must be used to obtain a satis
factory elastomer.
Depending on the particular ?ller
face area, which can be 900* square meters per gram or
used, best results are obtained when 30 to 100 parts of
more.
70 ?ller are used. The ?lling power of these ?llers will vary
The modi?ed silica ?llers can be prepared from any
depending on such factors as particle size and degree of
reinforcing silica ?ller having a surface area of at least
agglomeration. The amount of ?ller that is used will also
100 square meters per gram (e.g., fume silicas, silica
depend upon the polymer that is used. In general, the
aerogel, hydrogels, organogels and xerogels). The ?llers
viscosity of the polymer and the desired amount ‘of ?ller
can be prepared from ?llers that are composed of all 75 are in an inverse ratio to each other.
3,086,954
6
Since air does not inhibit vulcanization of these stocks
‘ If desired, small amounts of ?llers‘having surface areas
they can be vulcanized in an air oven to give an even
less than 100 square meters per gram, such as diatoma
ceous earth, can be used as extenders in combination with
cure throughout the section. These compositions can also
the above de?ned ?llers.
be vulcanized, in an autoclave.
.
I
..
_
inoperative upper limit. From 0.25 to 1 part of cyano
‘By using hot air vulcanization and a large quantity of
cyanoguanidine, a tough sponge is obtained. This vulcan
ization is usually carried out at 150° to 200° C. although
not required, a blowing agent can be used to aid in mak
guanidine is preferred for most compositions.
ing a sponge.
At least 0.1 percent' b'y'weight based on the weight of
p’olymerrof cyanoguanidine (dicyanodiamide) is used as
curing agent for these compositions although there is no
V
The compositions of this invention give el-astomers
As indicated in Table II, an excellent elastomer is ob-' 10
having excellent physical properties. In particular, these
tained when from 0.01 to 2.0 percent by weight based
elastomers have unusually high tear strengths. These
upon the weight of polymer of any. organic peroxide is
elastomers can be used any place where conventional
used in‘ combination with cyanog'uanidine. If only a
very 'small'amount of peroxide (e.g. ‘from 0.01 to 0.2 per
' siloxane'elastomers can be used.
These elastomers are
useful where conventional siloxane elastomers
cent) is used in combination with the cyanoguanidine, 15 especially
are unsatisfactory beacuse of lack of sufficient tear
higher tear strengths are often obtained with certain
strength. For example, these elastomers can be used in
rubber stocks (e.g. those rubber stocks not containing a
silicate) "than jwhene‘ithe‘r curing agent is iusedwa'l'one.
Examples of organic peroxides that can be used in com
" tire treads.
Theuse of cyanoguanidine as a curing agent enables
bination with‘ cyanoguanidine are: tert-butylperbenzoate, 20 the vulcanization of deep ‘sections of rubber having uni
form physical properties throughout. Unvulcanized stocks
benzoyl peroxide, dicurnyl peroxide, bis(2,4-dichloro
containing this curing agent do not cure appreciably dure
ing prolonged storage ‘at room temperature. Excellent
,elastomers are obtained when these stocks are cured in
benzoyl) peroxide and‘ v2,5-dimethyl¢2,5-di-t-butylperoxy
hexane. From 0.03 to 0.06 part of such-curing agents is
preferred. It‘ should be‘ pointed out that excellent results
are obtained when cyanoguanidine is the only curing
agent used.
‘_
‘From 0.1 to‘ 50 perecnt by weight of any of the ‘fol
lowing silicates'can also‘ be‘in‘cluded' in the rubber stock.
25
the presence of air.
The following examples are illustrative only and should
not be construed as limiting the invention which is prop
‘ erly' delineated in the appended claims.
The strip tear strengths were obtained by using a long
These silicates include orthosilicatesyin which the hydro
rectangular shaped specimen (1A6 _x ;1/2 _x 4_ in.) having a
carbon radicals’l'are monovalent aliphatic hydrocarbon 30 razor
blade cut 1.5 inches long forming a “trouser leg”
radicals of less than "7,‘ca'rbon atoms. Examples of such
'type specimen. The strip tear values are expressed as
fo'rthosilidates' are 'methylorthosilicate, ethylorthosilicate,
n-propylor'thosilicate,_ pentylorthosilicate, allylorthosili
‘pounds per inch tear strength required to propagate this
‘?aw. This method is described in detail by Revlin and
35 Thomas, J‘. Poly/Sci, 10, 291 (1953), and Greensmith
dipropylorthosilicate.
‘
v
‘and Thomas, I. ,Poly. Sci., 18, 189 (1955). The die B
I‘ Partial hydrolyzates of orthosilicates are commonly
tear strengths were obtained in accordance with ASTM
known'as polysilicfates. _ Speci?c examples of such silicates
cate, pentenylorthosilicate, hexyl'orthosilicate, and diethyl
are ‘methylpolysilicate, ethylpolysilicate, isopropylpoly
D624—54.
.
,
,
p
silicate, and n-butylpolysilicate.
In the examples the following materials were used:
Z4_mSi(OCH2CH2OZ')m in which Z is a monovalent
aliphatic hydrocarbon radical of less than 7 carbon atoms
and Z’ is a monovalent aliphatic hydrocarbon radical of
methylpolysiloxane containing .142 mol percent vinyl
These silicates include compounds of the formula 40 A. A high molecular weight hydroxyl-endblocked di
methylsiloxane.
v
.
'
B. A hydroxy-endblocked dirnethylsiloxane containing
less than 6 carbon atoms and m has a value of from 3 to
5.5 mol percent diphenylsiloxane. ,
4. Thus Z' can be any of such groups as methyl, ethyl, 45 C. A reinforcing ‘silica formed by, transforming sodium
isopropyl, tert-butyl, pentyl, vinyl allyl methallyl and
butadienyl. The silicate is produced by reacting a chloro
silane with the corresponding monoethers of ethylene gly
col or mixtures thereof to produce H01 and thesilieate.
‘ silicate in solution to a silica sol in the presence of an
ion exchange resin, re?uxing said sol with. HCl to pro
duce a silica having an average surface area of‘ from
250 to 500 square meters per gram and treating said
silica to saturate its surface with trimethylsilyl units
through SiOSi bonds. This silica has from 0.08 to 0.1
The monoethers of ethylene glycol are produced byuthe 50
normal ether reactions of the corresponding alcohols
(Z'OH) with ethylene glycol in a,1:1_ addition. It is
trimethylsilyl units per SiO2.
.
_ I
possible then to have more'than one‘ specie of the group
D. A reinforcing fume, silica having an average surface
area of at least 350 square meters per gram, said sur
——(OCH2CH2OZ’)> on each silicate silicon.
The silicate component'can be one silicate or any com 55
face being treated but not saturated with trimethylsilyl
units. This silica has from 0.07 to 0.09 trimethylsilyl
bination of the silicates described ‘above. It should be
remembered that the silicate 'c‘omponent'is‘ an optional
ingredient...‘ The silicates are used primarily'to improve
E. A reinforcing fume silica havingan average surface area
the‘v thermalgstability of the elastomer and to aid in the
of at least 350 square meters pergram, said surface
cure of the’ stock. The preferred silicate is ethylpoly 60
being saturated vwith diphenylmethylsilyl units. This
3, silica has from 0.08 to 0.1 diphenylmethylsilyl units per
lThe‘compositions ‘of this invention can contain other
S102.
F. A reinforcing silica formed by transforming silicate in
additives such as compressionfset additives thermal sta
per SiO2
silicate.
v
.
_
.
.
_
biliz‘ers,‘ oxidation inhibitors,’"plasticizers, pigments ‘and
solutionto a silica sol in the. presence of an ion ex
bers. Care must be taken, however, that these additives
quantities of hydroxylated resins" can also be included in
silica having an average surface area of from 250 to
500 square meters per gram and treating said silica to
saturate its surface with dimethylsilyl units through
these
SiOSibonds.
1other material commonly employed in or'ganosilicon'rub 65 ' change resin, re?uxing said sol with HCl ‘to produce a
be at least as heat-stable as the base composition. Small
compositions.
,
v
p
v
,
g
p
,
_
The compositions of thishinve‘ntiQIlT are cured merely by 70 _G. Tertiarybutylperbenzoate.
H. Cyanoguanidine.
heating to a temperature su?‘icient to cause vulcanization.
I. Ethylpolysilicate.
Press vulcanization is an. effective method of curing these
J. n-Propy-lorthosilicate.
V
stocks. Usually a temperature of from 160°‘ to 200° C.
‘K. Beta-methoxyethylorthosilicate.
for 10 to 15 minutesiislsu?lcient. An aftercure at‘ 200°
to 250° C. for'l to 24 hours is also usually desirable. 75 L. A hydroxyl endblocked block copolymer consisting of
3,086,954.
‘
8
7
75 mol percent (CH3)2SiO units and 25 mol percent
(6) A hydroxyl endblocked copolymer consisting of 10
0.5(CHs)zSi——C6H1——Si(CH3)z0.5
mol percent methylchloromethylsiloxane and “90 mol
M. A trimethyl-treated reinforcing silica cogel having a
percent dimethylsiloxane.
surface area of at least 300 square meters per gram
EXAMPLE 2
and having from 0.08 to 0.1 organosilyl units per SiO2.
5
N. A hydroxyl endblocked dimethylpolysiloxane_
.
O. A hydroxyl endblocked dimethylpolysiloxane contain-
t at a com matlon. (if Peron e an
6 t hen lmeth lsiloxane
y
y
.
P;1ys111°ate%)_can, be Incorporated 1am 'the elastqgeer and
ing 0.142 mol percent vinylmethylsilioxane and 7.5 mol
perc n P
.
This example demonstrates that a silicate v(e.g., ethyl
cyanoguam me can
be used as a vulcanizmg agent. The elastomers were pre
'
pared in the proportions shown in the following table:
Table II
100
i
Parts
Parts of
of
Siloxane
Filler
Parts of
Tensile
Percent
Strip
Vulcaniz-
Parts of Strength, Elonga-
Tear,
ing Agent Additive
p.s.i.
tlon at
p.s.i.
Die B
Break
60
60
60
60
EXAMPLE 1
30
The improved physical properties obtained when cyano
0
G
C
c
.5
.5
.5
.5
GH
G
H
2, 050
1,630
1, 850
1, 820
520
830
400
825
78
86
88
133
200
219
219
253
60 C
60 o
.5 3g and
.5 '01; and
2,110
2, 005.
710
705
104
119
24s
240
60
60
60
60
60
.5H
.5 H
.5 H
.5 H
1. H
1, 775
1, 950
1,842
1,480
1, 395
865
900
910
927
930
111
112
121
102
93
262
268
272
215
216
0
0
0
0
C
Samples 1 through 6 were heated for two hours at 200°
C. prior to the addition of the vulcanizing agent. The vul
canizing agent was then added and the sample was press
guanidine is used as a vulcanizin-g agent in place of terti
arybutylperbenzoate are shown in Table I. The elasto
vulcanized for 10 minutes at 185° C. and aftercured for
mers were prepared in the proportions shown in the fol
1 hour at 150° C. and then for 4 hours at 250° C.
lowing table. Samples 1' and 4 were press vulcanized for 35
When any of the following peroxide catalysts are sub
10 minutes at 150° C. Samples 2 and 3 were press
stituted for the tertiarybutylperbenzoate in sample 5 of
vulcanized for 10 minutes at 185° C. Samples 1, 2 and
Table II, an elastomer with good physical properties is
3 were aftercured for one hour at 150° C. and then for
obtained. The amounts are stated in parts by weight
4 hours at 250° C.
based on the weight of the siloxane.
Table I
100
Parts of
Siloxane
Parts of
Filler
Parts of
Tensile Percent
Vulcan- Parts of Strength, Elongaizing
Additive
p.s.i.
tion at
Agent
break
60 C
60 C
60 C
.5 G
.25 H
.1 H
3 I
3 I
3 I
1,758
1,875
1, 875
60 O
20 H
3 I
805
440
770
810
An excellent sponge was obtained by curing sample
minutes in place of vulcanizing the sample in a press.
This sponge had a tough skin which was about .010 inch 55
thick.
An excellent elastomer is obtained when any of the
following siloxane polymers are substituted for the poly
mer in sample 2, Table I:
mol percent diphenylsiloxane and 50 mol percent di
methylsiloxane.
71
108
108
800 ________ -_
number 4 in an air-circulating oven at 150° C. for 20
(‘1) A hydroxyl endblocked copolymer consisting of \50
Strip
Tear,
p.s.i.
60
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
0.01 part tertiarybutylperbenzoate
1.0 part tertiarybutylperbenzoate
2.0 parts tertiarybutylperbenzoate
.05 part di-t-butylperoxide
.05 part benzoyl peroxide
.05 part di-cumylperoxide
.05 part 2,5-dimethyl-2,S-di-t-butylperoxy hexane
.05 part bis(2,4-dichlorobenzoyl)peroxide.
When any of the following silicates are substituted for
the ethylpolysilicate in sample 4 of Table II, an excellent
elastomer is obtained. The amounts of additive are ex‘
(‘2) A hydroxyl endblocked copolymer consisting of 25
mol percent 3,3,3-tri?uor0propylmethylsiloxane and 75 65 pressed in parts by weight based upon the weight of the
siloxane.
mol percent dimethyl siloxane.
(3) A hydroxyl endblocked copolymer consisting of 25
('1) 50 parts ethylpolysilicate
mol percent butylmethylsiloxane and 75 mol percent
(2) 30 parts n-propylorthosilicate
dimethylsiloxane.
(4) A hydroxyl endblock copolymer consisting of 10 mol 70 (3) ‘110 parts beta-methoxyethylorthosilicate
(4) 3 parts methylpolysilicate
percent methyloctadecylsiloxane and ‘90 mol percent di
methylsiloxane.
(‘5) 3 parts n-pentylpolysilicate
(5) A hydroxyl endblocked copolymer consisting of 10
('6) 3 parts n-pentylorthosilicate
mol percent methylcyclohexylsiloxane and 90 mol per
(7) 3 parts Si(OCH2CH2OCH=CH2)4
cent dimethylsiloxane.
75 (8) 3 parts Si‘(OCH2CH2OCH2CH2CH2CH3)4
siosegasr
10!
9
EXAMPLE 4
(‘9) 3 parts PhSiKOCH‘éCHgOCHQQ
(10) 3 parts
100 parts of a hydroxyl endblocked'dimethyl‘siloxane
polymer With-aviscosity of 2,250 cps. at 25° C., 30 par-ts
of ?ller (C), 3 parts of ethylpolysilica-te ‘and 2 parts of
CH3
CHz=JJ—CH2Si(OCH2CHnOCHa):
_
5 cyanoguanidine were mixedtogether.
Thegcomposition
(11V) 3 parts>CF3CH2OI‘T2§1(0CH2CH2OCH3)3
was vulcanized in a 150° C. air- oven for 45 minutes. An
(‘12) 3 parts ethylorthosilicate
(13) 3 parts n-allylorthosilicate
elastic sponge was obtained.
EXAMPLE 5:
_
_ _
10
100 parts of siloxane (A), 1.5 partstof?ller (C), and
111 3115 example, cyanogllanldlne 15‘ used as a Vulcamzlng
10 parts of cyanoguanidine were mixed together. ' The
agent for rubber stocks containing a variety of- ?llers. The
sample was pressrvulcanized at"185 ° C; for 15 minutes.
Proportions used and the physical‘properties 0f ‘the elastomers are shown‘in‘Table -III. The samples were press‘ vul-
A satisfactory elastomer was obtained.
EXAMPLE. 6
canized‘ for 10 minutes at 185° C. and‘ then aftercured 1‘5
‘ V
for 1 hour at 150° C. and then for 4 hours at 250° C.
In this example, vv'cyan'ogua'nidinev is used as a vulcan
Sample 2 was'heated for two‘hours at 200° C. prior to
the addition of the vulcanizing agent.
izing agent for silphenylene containing elastomersi. The
proportions used and the physical properties'of the elas
Table III
100
Parts of
Siloxane
A
4
5---”---
Parts of
Filler
50 D
Parts of
Tensilev Percent
Vulcan- Parts of Strength; Elongaizing
Additive
p.s.l.
tion at
Agent
break
Strip
Tear; -Die,B
p.s.i.
5H
a1
1.200
520
87
192
A
50 E
5H
31
1,150
s20
81
. 270
A
A
A
50 F
75 0
50M
5H
5H
5H
3515
ar
31
1,590
1, 710
1.910
990
785
825
100
131
118
24a‘
29s
255
An excellent elastomer is obtained when the ?ller used
in sample 2 of Table III is saturated with any of the
following organosilyl groups in‘ place of diphenylmethyl-
tomers are shown-in Table
The samples were press
vulcanized’ for‘ 10"inin'utes at 185 ° C; and then after
cured‘ for 1' hour at 150° C; and then for 4 hours at
si1y1': triethylsilyl, di-n-propylmethylsilyl, dimethylbutyl-
250° C.
Table IV
,
100
Parts 01‘
I
.
\
Parts of
Polymer
Filler
'
j Parts of
Vulcanizing
;Parts of;
Addi-
Agent
Percent
p.s.i.
“tion at _
‘
Strip
Break-
Tear,
p.s.i.
5
1 ___________ __
L
. 550
1,5 11V
31
2,730 1
s03- ________ __
- 2 ___________ __
L
~ 500
.ggand
31
2,517
557
a; __________ -_
L
500
12135115
L
500
I511
________ _-
2:559
L
50 0
.2 (£31 and‘
L
60M
15H
2,585
3I
' a1
silyl, phenylrnethylsilyl, and dimethy1-3,3,3-tri?uoropro
pylsilyl.
Tensile‘
Strength, iElonga-
tives
.
-
________ -_
747 . ....... 970
________ __
2, 705
8.531
222
‘2, 815
970.
214
7
'When any of the‘ following orga'no‘silicon polymers are
substituted for the polymer in sample L'Table IV, an
’
An excellent‘el‘astome'r is obtained when. a‘?ller pre
pared by the following method is substituted (at a 35 55 7excellent‘ elastomer is obtained:
parts ?ller loading) for the ?ller in sample‘ 2», Table III;
61.4 g. of a cogel having an average surface area of
‘(1) A hydroxyl‘ endbloekedr copolymer consisting of
about 700 square meters per gram‘ and composed of 80
7511101 percent (CH3)2Si'O' and 25 mol percent
mol percent S102 and 20 mol percent CH3SiO1_5 is
stirred for one hour with 230ml. of isopropanol alcohol 60
onCHSIZSiCZHiSMCHQxQE.,
and 165 ml. of 38 percent hydrochloric acid, 10 grams
(2) A hydroxyl endblocked copolymer consisting of 25
of trimethylchlorosilane are added and the mixture is
‘mole percent (CH3) ZSiO' and 75'mol. percent
stirred for 11/2 hours. The layers are separated and the
‘organic layers are evaporated to dryness. The resulting
0.5 (CH3) 2SiC5H4Si (CH3) 20.5
modi?ed organo ?ller is heated for 40 hours at 110° C. 65
The resulting material is a powder having (CH3)3SiO_5
(3) A hydroxyl endblockedcopolym'er consisting of 80
units attached through siloxane units to different silicon
mol percent (CH3)2SiO-and 20 mol percent
atoms so that the surface of the substrate is saturated with
organosilyl units. This ?ller has a surface area of about
700 square meters per gram.
O.5(CHa)2SiCH2Si(CH3) 20.5
When a cogel composed of 50. mol percent Si02 and 50
(4) A ‘hydroxyl end-blocked copolymer of 75 mol per
mol percent CH3SiO‘L5 is treated by the above method
cent (CH3)2Si0.and 25 mol percent
and substituted (at a ?ller loading of 35 parts per 100
parts of siloxane) for the ?ller used in sample 2, Table
III,‘ an excellent elastomer is obtained.
75
oswnm'sigc-si(onmos
-
3,086,954
11..
12
(5) A hydroxyl endblocked copolymer of 75 mol per
in an amount of fromv 30 to 100 parts by weight per 100
cent (CH3)2SiO and 25 mol percent
parts of the organosilicon polymer.
4. A heat-curable composition in accordance with
claim 1 wherein the hydroxylated organosilicon polymer
oEwHQZSiQQO-SWHB)20.5
is an organopolysiloxane in which the organic radicals
are monovalent hydrocarbon radicals wherein at least 50
mol percent of the total organic radicals are methyl and
(6) A hydroxyl endblocked copolymer of 75 mol per
cent (CH3)2SiO and 25 mol percent
o.nonmswrn-Qomsnom)20.5
' (7) A hydroxyl endblocked
wherein the ?ller substrate is composed of SiOz units, said
substrate being saturated with R’2R”Si— units, wherein
1.0,
O.5(CH3)SiC6H4Si(CH3)20.=-,
R" and R’ are alkyl radicals of less than 6 carbon atoms
with at least 50 mol percent of the total R’ ‘and R” groups
being methyl and wherein the modi?ed silica ?ller is
present in an amount of from 30 to 100 parts by weight
polymer.
per 100 parts of the organosilicon polymer.
(8) A hydroxyl endblocked
15
5. A heat curable composition ‘of matter consisting es—
sentially of
(1) hydroxylated organosilicon polymers selected from
polymer.
That which is claimed is:
1. A heat curable composition of matter consisting
the group consisting of
(A) organopolysiloxanes in which the organic
essentially of
(1) hydroxylated organosilicon polymers selected from
the group consisting of
(A) organopolysiloxanes in which the organic
monovalent hydrocarbon radicals and halogenat
ed monovalent hydrocarbon radicals, and
(B) polymers containing the units of the structure
groups are selected from the group consisting of
groups are selected vfrom ‘the group consisting
‘of monovalent hydrocarbon radicals and halo 25
rr
SiiXSi-O
Y
genated monovalent hydrocarbon radicals, and
(B) polymers containing units of the structure
Y
Y
'
slixsli-o
30
Y Y
wherein X is a divalent radical composed of
carbon and hydrogen atoms and no more than
one oxygen atom, said ‘oxygen ‘atom being pre 35
sent in a
wherein X is a divalent radical composed of
carbon and hydrogen atoms and no more than
one oxygen atom, said oxygen atom being pre
sent in a
group and Y is a monovalent hydrocarbon radi
cal,
said organosilicon polymers having a silicon bonded OH
content of at least 2 OH per molecule and having an
group and Y is a monovalent hydrocarbon 40 average ‘of from 1.95 to 2.05 monovalent organic groups
attached to silicon per silicon atom ‘and having an average
radical,
of at least 400 silicon atoms per molecule,
said organosilicon polymers having a silicon bonded OH
(2) at least 10 percent by weight based on the weight
content of at least 2 OH per molecule and having an
of (l) of a modi?ed silica ?ller comprising ?nely
average of from 1.95 to 2.05 monovalent organic groups
divided hydrophobic solid particles having a surface
attached to silicon per silicon ‘atom and having an average
area of at least 100 m.2/g., each of ‘said particles
45.
of at least 400 silicon atoms per molecule,
(2) at least 10 percent by weight based ‘on the weight
of (1) of a modi?ed silica ?ller comprising ?nelye
divided hydrophobic solid particles having a surface
area of at least 100 m.2/g., each of said particles
consisting essentially of a polymeric siliceous sub 50
strate consisting essentially of
(A) from 50 to 100 inclusive mol percent of units
of the formula Sioz, and
(B) from 0 to 50 inclusive mol percent of units of
the formula RSiOL5, wherein R is selected from‘ 55
the group consisting of alkyl radicals of less
than 6 carbon atoms and phenyl, there being
(C) organosilyl units selected from the group
consisting of R'R"Si= and R'2R"Si—, wherein 60
R’ is selected from the group consisting of alkyl
radicals of less than 6 carbon atoms and phenyl,
and R" is selected from the group consisting of
alkyl radicals of less than 6 carbon atoms, 3,3,3
tri?uoropropyl ‘and phenyl radicals, in an 65
amount such that the molar ratio of (C) units to
total (A) and (B) units is not in excess of 0.6,
said organosilyl units being attached to silicon,
atoms in the surface of said substrate through
consisting essentially of a polymeric siliceous sub
strate consisting essentially of
(A) from 50 to 100 inclusive mol percent of units
‘of the formula SiO2, and
(B) from O to 50 inclusive mol percent of units
‘of the formula RSiO1_5, wherein R is selected
from‘ the group consisting of alkyl radicals of
less than 6 carbon atoms (‘and phenyl, there
being
(C) organosilyl units selected from the group con
sisting of R'R"Si= ‘and R’2R"Si——, wherein R’
is selected from the group consisting of alkyl
radicals of less than 6 carbon atoms and phenyl,
and R” is selected from the group consisting of
alkyl radicals of less than 6 carbon atoms, 3,3,3
tri?uoropropyl and phenyl radicals, in an
amount such that the molar ratio of (C) units
to total (A) and (B) units is not in excess of
0.6, said organosilyl units being attached to
silicon atoms in the surface of said substrate
through SiOSi linkages, and
(3) from 0.01 to 2 percent by Weight based upon the
Weight of (1) of an organic peroxide and at least
0.1 percent by weight based on the weight of (1) of
SiOSi linkages, and
cyanoguanidine.
(3) at least ‘0.1 percent by weight based on the weight
6.
The cured, solid, elastic product of claim 5.
of (1) of cyanoguanidine.
7.
A heat-curable composition in accordance with
2. The cured, solid, elastic product of claim 1.
claim 5 wherein the hydroxylated organosilicon polymer
3. A heat-curable composition made in accordance
with claim 1 wherein the modi?ed silica ?ller is present 75 is an organopolysiloxane in which the organic radicals
are monovalent hydrocarbon radicals, wherein at least 50
3,086,954
'13
mol percent of the total organic radicals are methyl‘ and
wherein the ?ller substrate‘ is composed of SiO;, units,
isaidsubs'trate being saturated with R’2R”Si— units where
‘ of (1) of cyanoguanidine.
_ 10. ‘The heat-curable composition of _matter in ac
in; R’ and R" are alkyl radicals of less than 6 carbon.
cordance wtih claim 8 wherein‘the modi?ed silica ?ller is
present in an amount of from‘ 310 to 100 parts by weight
per 100 parts of organosilicon polymer.
11. A heat-curable composition in accordance with
"
' 8‘. A heat-curable fycompositio'nl of ‘matter consisting
essentially
of‘
"
‘
"
"
'
'
'
claim 8 wherein the hydroxylated organosilicon polymer
10 is an organopolysiloxane in which the organic radicals are
monovalent hydrocarbon ‘radicals, wherein at least 50
(l) "ihydroxylated organosilicon polymers selected
from ‘the group consisting of
"
'
9. V'HI‘hVe cured, solid, elastic product of claim 8.
atoms ‘with at least mp1 p?liqeht of the total R’ and R'f
‘grasps being methyl‘ and wherein‘ ithe‘modi?ed silica ?ller
is present in'an amount of from, 30 to 1100 parts by Weight
p’er’lOO' parts of the organosilicon polymer.
14
(4) at least 0.1 percent by weight based on the weight
mol percent ofthe total Qrganis; raslisals aramethyl and
'
wherein the ?ller substrate is composed of. SiO2,units, said
(A) ‘organopoly'siloxa’nes in which the organic
substrate being saturated
) 'groups'ajre selected from the group consisting of
R'2R”Si— fu‘nits wherein
monovalent f hydrocarbon radicals" and, halo. 15 Rf'and =R’T are alkyl radicals of ‘less_>than_6: carbon atoms
with at least 50 mol percent of the total R’ and -R" groups
genated monovalent hydrocarbon radicals, and
being methyl‘ and wherein the ' modi?ed silica ?ller is
.(B) ' ‘polymers containing the‘ units ‘of the structure
present in amount of from 30 to 10._0_ parts by ‘weight per
lOOjparts of the organosilicon polymer and wherein com
Y Y
s'txsh-o
20 pound (3) is present in an amount from 0.1 to 15 percent
by weight based on the weight of the polymer, saidcom
pound (3),‘ being a partial hydrolyzate of an orthos‘ilicate
Y Y
__wherein X is a divalent radical composed of
‘ ‘carbon and hydrogen" atoms and norn'ore than
one oxygen atom, said oxygen atom being pres
. an? in a
in which the hydrocarbon radicals are alkyl radicals of
less than 5 carbon atoms.
25 12. A heat-curableicomposition of matter consisting
essentially I of
'
'
'
i
‘
'
(1), hydroxylated‘ organosilicon polymers selected
_+_0_+_
from the group, consisting of
' (A) organopolysiloxanes in which the organic
groups are selected from the group consisting of
group and Y is a monovalent hydrocarbon
radical,
monovalent hydrocarbon radicals and halo
said organosilicon polymers having a silicon bonded OH
content of at least 2 OH per molecule and having an
average of from 1.95 to 2.05 monovalent organic groups
attached to silicon per silicon atom and having an average
35
of at least 400 silicon atoms per molecule,
(2) at least 10 percent by Weight based on the weight
of (1) of a modi?ed silica ?ller comprising ?nely
divided hydrophobic solid particles having a surface
area of at least -100 m.2/g., each of said particles
consisting essentially of a polymeric siliceous sub 40
strate consisting essentially of
(A) from 50 to 100 inclusive mol percent of units
of the formula SiO-Z, and
(B) from 0 to 50 inclusive mol percent of units
of the formula =RSiOL5, wherein R is selected 45
from the group consisting of alkyl radicals of
less than 6 carbon atoms and phenyl, there
genated monovalent hydrocarbon radicals, and
(B) polymers containing the units of the structure
1.’SiXSi-O
i
Y Y
wherein X is a divalent radical composed of
carbon and hydrogen atoms and no more than
one oxygen atom, said oxygen vatom being pres
group and Y is a monovalent hydrocarbon radi
cal,
said organosilicon polymers having a silicon bonded OH
content of at least 2 OH per molecule and having an
being
average of from 1.95 to 2.05 monovalent organic groups
(C) organosilyl units selected from the group
attached to silicon per silicon atom and having an average
50
consisting of R'»R"Si= and R'2R"Si—, wherein
of at least 400 silicon atoms per molecule,
R’ is selected from the group consisting of alkyl
(2) at least 10 percent by Weight based on the weight
radicals of less than 6 carbon atoms and phenyl,
of ( 1) of a modi?ed silica ?ller comprising ?nely di
and R" is selected from the group consisting of
vided hydrophobic solid particles having a surface
alkyl radicals of less than 6 carbon atoms, 3,3,3~
area of at least 1-00 m.2/g., each of said particles con
tri?uoropropyl and phenyl radicals, in an 55
sisting essentially of a polymeric siliceous substrate
amount such that the molar ratio of (C) units to
consisting essentially of
total (A) and (B) units is not in excess of 0.6,
1( A) from 50 to 100 inclusive mol percent of units
said organosilyl units being attached to silicon
of the formula SiO2, and
atoms in the surface of said substrate through
(B)
from 0 to 50 inclusive mol percent of units
60
SiOSi linkages, and
of the formula ‘RSiOm, wherein R is selected
(3) from 0.1 to 50 percent by Weight based on the
from the group consisting of alkyl radicals of
weight of (1) of a compound selected from the
less than 6 carbon atoms and phenyl, there being
group consisting of
(C)
organosilyl units selected from the group
(A) orthosilicates and their partial hydrolyzates
consisting of R'R”Si= and R'2R"Si—, wherein
in which the hydrocarbon radicals are mono 65
R’ is selected from the group consisting of alkyl
valent aliphatic hydrocarbon radicals of less
than 7 carbon atoms, and
(B) silicates of the formula
70
in which Z is a monovalent aliphatic hydrocar
bon radical of less than 7 carbon atoms, Z’ is a
monovalent aliphatic hydrocarbon radical of
less than 6 carbon atoms and m: has a value
from 3 to 4 inclusive, and
radicals of less than 6 carbon atoms and phenyl
and R" is selected from the group consisting of
less than 6 carbon atoms, 3,3,3-triiluoropropyl
and phenyl radicals, in an amount such that the
molar ratio of (C) units to total (A) and (B)
units is not in excess of 0.6, said organosilyl
units ‘being attached to silicon atoms in the sur
face of said substrate through SiOSi linkages,
(3) from 0.1 to 50 percent by weight based on the
3,086,954
weight of ( 1) ofea compound selected from the
group consisting of
(A) orthosilicates and their partial hydrolyzates
16
silica ?ller is present in an amount of from 30 to 100
parts by weight per 100 parts of the organosilicon poly
mer and wherein compound (3) is present in an amount
in which the hydrocarbon radicals are mono
from 0.1 to 15 percent by weight based on the weight
valent aliphatic hydrocarbon radicals of less
of the polymer, said compound (3) being a partial hy
drolyzate of an orthosilicate in which the hydrocarbon
than 7 carbon atoms, and
(B) silicates of’ the formula
radicals are alkyl radicals of less than 3 carbon atoms.
15. The method of making a vulcanized silicone rub
ber which comprises heating the composition of claim 1
in which Z is a monovalent aliphatic hydrocar 10 to a temperature su?icient to cause vulcanization.
bon radical of less than 7 carbon atoms, Z’ is a
16. The method of making a vulcanized silicone rub
monovalent aliphatic hydrocarbon radical of
ber which comprises heating the composition of claim 4
less than 6 carbon atoms and m has a value from
to a temperature su?icient to cause vulcanization.
3 to 4 inclusive, and
17. The method of making a vulcanized silicone rub
(4) from 0.01 to 2 percent by weight based on the 15 ber which comprises heating the composition of claim 5
weight of (1) an organic peroxide and (5) at least
0.1 percent based on the weight of (1) of cyano
guanidine.
13. The cured, solid, elastic product of claim 12.
14. -A heat-curable composition in accordance with
claim 12, wherein the hydroxylated organosilicon poly
mer is an organopolysiloxane in which the organic radi
cals are monovalent hydrocarbon radicals, wherein at
least 50 mol percent of the total organic radicals are
methyl and wherein the ?ller substrate is composed of 25
SiOz units, said substrate being saturated with R’2R"Si—
units wherein R’ and R" are alkyl radicals of less than
6 carbon atoms with at least 50 mol percent of the total
R’ and R" ‘groups being methyl and wherein the modi?ed
to a temperature su?icient to cause vulcanization.
18. The method of making a vulcanized silicone rub
ber which comprises heating the composition of claim 8
to a temperature sufficient to cause vulcanization.
19. The method of making a vulcanized silicone rub
ber which comprises heating the composition of claim 12
to a temperature su?icient to cause vulcanization.
References Cited in’the ?le of this patent
UNITED STATES PATENTS
2,938,010
Bluestein ____________ __ May 24, 1960
813,972
Great Britain ________ __ May 27, 1959
FOREIGN PATENTS
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