Heat resistant organopolysiloxane compositions

There is disclosed a heat-resistant agent which exhibits good solubility in various organopolysiloxanes and which confers superior heat-resistance thereto, said heat-resistant agent having the formula ##STR1## wherein R.sup.2 is independently selected from hydrocarbon or halogenated hydrocarbon groups having 1 to 10 carbon atoms, R.sup.1 is independently selected from R.sup.2 or a eugenol residue, m is an integer having an average value of 5 to 500 and n is an integer having an average value of 0 to 500, with the proviso that there is at least one eugenol residue in the molecule. Also disclosed is a composition comprising an organopolysiloxane and the above described heat-resistant agent.

FIELD OF THE INVENTION 
This invention relates to a heat-resistant agent for organopolysiloxanes 
and to a heat-resistant organopolysiloxane composition. In detail, it 
relates to a heat-resistant agent for organopolysiloxanes that exhibits 
good solubility in various organopolysiloxanes, including 
dimethylpolysiloxane, and which imparts superior heat-resistance to these 
organopolysiloxanes. The invention also relates to a heat-resistant 
organopolysiloxane composition that contains this heat-resistant agent for 
organopolysiloxanes and that has superior transparency and heat 
resistance. 
BACKGROUND OF THE INVENTION 
Known heat-resistant agents for organopolysiloxanes include 
organopolysiloxanes having hindered phenol residues (Japanese Patent 
Announcement 47-3922 (1972) and Japanese Patent Announcement 7-42472 
(1995) and organopolysiloxanes having phenol residues (Japanese Patent 
Application Early Disclosure No. 7-216376 (1995)). 
However, organopolysiloxanes having hindered phenol residues have large 
organic group components, for which reason they exhibit good solubility in 
organopolysiloxanes having, for example, long chain alkyl groups, aryl 
groups and aralkyl groups, and can confer heat resistance on these 
organopolysiloxanes. However, they lack solubility, for example, in 
dimethyl polysiloxane, dimethyl siloxane-methylphenylsiloxane copolymer 
and dimethylsiloxane-methyl(3,3,3-trifluoropropyl siloxane copolymer, all 
of which comprise dimethylsiloxane units. These diorganopolysiloxanes are 
turbid and sufficient heat-resistance cannot be conferred on these 
diorganopolysiloxanes. Likewise, organopolysiloxanes having phenol 
residues cannot confer sufficient heat resistance on organopolysiloxanes. 
SUMMARY OF THE INVENTION 
An object of this invention is to provide a heat-resistant agent for 
organopolysiloxanes with which various organopolysiloxanes, including 
dimethylpolysiloxane, exhibit good solubility and which confers superior 
heat-resistance on these organopolysiloxanes. Another object of the 
invention is to provide a heat-resistant organopolysiloxane composition 
that contains this heat-resistant agent for organopolysiloxanes and that 
has superior transparency and heat resistance. 
The heat-resistant agent for organopolysiloxanes of this invention is 
represented by the general formula: 
##STR2## 
wherein, R.sup.1 is a monovalent hydrocarbon or halogenated hydrocarbon 
group of 1 to 10 carbon atoms or a eugenol residue of the formula 
##STR3## 
R.sup.2 is a monovalent hydrocarbon or halogenated hydrocarbon group of 1 
to 10 carbon atoms, m is an integer of 5 to 500 and n is an integer of 0 
to 500. However, when n is 0, at least one of the R.sup.1 groups bonded to 
a terminal of the molecular chain is the aforementioned eugenol residue. 
The heat-resistant organopolysiloxane composition of this invention is 
characterized in that it is comprised of (A) an organopolysiloxane 
(different from the organopolysiloxane indicated by the aforementioned 
general formula) and of (B) the aforementioned heat-resistant agent for 
organopolysiloxanes. 
The present invention has been disclosed in Japanese Patent Application 
Number Hei 07/334006, the full disclosure of which is hereby incorporated 
by reference. 
DETAILED DESCRIPTION OF THE INVENTION 
First, we shall present a detailed description of the heat-resistant agent 
for organopolysiloxanes of this invention. 
R.sup.1 of above formula (I) is a monovalent hydrocarbon or halogenated 
hydrocarbon group of 1 to 10 carbon atoms or a eugenol residue of the 
formula: 
##STR4## 
The monovalent hydrocarbon group of 1 to 10 carbon atoms includes, for 
example, alkyl groups such as methyl, ethyl or propyl aryl groups such as 
phenyl or tolyl and halogenated alkyl groups such as 3,3,3-trifluoropropyl 
groups. R.sup.2 in the aforementioned formula is also a monovalent 
hydrocarbon or halogenated hydrocarbon group of 1 to 10 carbon atoms and 
is independently selected from the same monovalent hydrocarbon or 
halogenated hydrocarbon groups of 1 to 10 carbon atoms as R.sup.1. In the 
aforementioned formula, m is an integer of 5 to 500 and n is an integer of 
0 to 500. When m and n in formula (I) are both positive integers, n/m 
should be 0.001 to 1. However, when n is 0, it is necessary that at least 
one R.sup.1 that is bonded to a terminal of the molecular chain is a 
eugenol residue as described above in Formula II. The viscosity of the 
heat-resistant agent for organopolysiloxanes at 25.degree. C. should be, 
for example, 10 to 100,000 centipoise. 
Preferably, the heat-resistant agent for organopolysiloxanes is represented 
by the general formula 
##STR5## 
wherein, m is an integer of 5 to 500, a heat-resistant agent for 
organopolysiloxanes represented by the general formula 
##STR6## 
wherein, m is an integer of 5 to 500 and p is an integer of 1 to 500 or a 
heat-resistant agent for organopolysiloxanes representative by the general 
formula 
##STR7## 
wherein, m is an integer of 5 to 500 and p is an integer of 1 to 500. 
Next, we shall present a detailed description of the heat-resistant 
organopolysiloxane composition of this invention. 
There are no particular limitations on the organopolysiloxane (A) which is 
the principal component of this invention as long as it is an 
organopolysiloxane that is not an organopolysiloxane as indicated by the 
general formula (I) above. Its molecular structure can be, for example, 
straight chain, straight chain having some branches, branch chain or 
cyclic. The straight chain form is particularly desirable. These 
organopolysiloxanes which are the principal component can be, for example, 
dimethylpolysiloxanes, both terminals of the molecular chain of which are 
blocked by trimethylsiloxy groups; dimethylsiloxane-methylphenylsiloxane 
copolymer, both terminals of the molecular chain of which are blocked by 
trimethylsiloxy groups; dimethylsiloxane-diphenylsiloxane copolymer, both 
terminals of the molecular chain of which are blocked by trimethylsiloxy 
groups, methylvinyl polysiloxane both terminals of the molecular chain of 
which are blocked by trimethylsiloxy groups, dimethylsiloxane-methylvinyl 
siloxane copolymer, both terminals of the molecular chain of which are 
blocked by trimethylsiloxy groups; dimethylsiloxane-methyl 
(3,3,3-trifluoropropyl)siloxane copolymer, both terminals of the molecular 
chain of which are blocked by trimethylsiloxy groups; 
dimethylpolysiloxane, both terminals of the molecular chain of which are 
blocked by silanol groups; dimethylsiloxane-methylphenylsiloxane 
copolymer, both terminals of the molecular chain of which are blocked by 
silanol groups; and dimethylsiloxane-methylvinylsiloxane copolymer, both 
terminals of the molecular chain of which are blocked by silanol groups. 
In the heat-resistant organopolysiloxane composition of this invention, 
dimethylsiloxane units are the principal components of the heat resistant 
agent for organopolysiloxanes (B). They exhibit superior solubility in 
such diorganopolysiloxanes (A) as dimethyl polysiloxane, 
dimethylsiloxane-methylphenylsiloxane copolymer and 
dimethylsiloxane--methyl (3,3,3-trifluoropropyl) siloxane copolymer. 
Therefore, when these diorganopolysiloxanes are used as the principal 
component(A), superior heat resistance can be conferred on these 
diorganopolysiloxanes without loss of the transparency. 
The viscosity of the organopolysiloxane (A) which is the principal 
component should be, for example, 10 to 1,000,000 centipoise. 
The content of the aforementioned heat-resistant agent for 
organopolysiloxanes (B) in the heat-resistant organopolysiloxane of this 
invention should be, for example, about 0.01 to about 20 percent based on 
the total weight of (A) and (B). 
Optional components may be added to the instant compositions including, for 
example, known heat resistant agents, inorganic fillers such as famed 
silica, wet process silica, sintered silica, fumed titanium dioxide, 
pulverized quartz, diatomaceous earth, aluminum hydroxide, aluminum oxide, 
magnesium oxide, aluminosilicic acid, iron oxide, zinc oxide, calcium 
carbonate, zinc carbonate and mica, pigments such as carbon black and 
dyes. These may be compounded with the heat-resistant organopolysiloxane 
composition of this invention as long as the objectives of this invention 
are not destroyed. The heat-resistant organopolysiloxane compositions of 
this invention can be used, for example, as fan clutch fluid, viscous 
coupling oil, lubricants and releasing agents.

We shall now present detailed descriptions of the heat-resistant agent for 
organopolysiloxanes and the heat-resistant organopolysiloxane compositions 
of this invention by means of examples. The viscosities in the examples 
are values determined at 25.degree. C. 
REFERENCE EXAMPLE 1 
Six hundred grams of dimethyl polysiloxane both terminals of the molecular 
chain of which were blocked by dimethylhydrogen siloxy groups (content of 
silicon atom bonded hydrogen atoms=0.17 wt %) as indicated by the formula 
##STR8## 
and 0.7 g of isopropyl alcohol solution of 2 wt % monochloroplatinic acid 
were introduced into a one liter round-bottom flask equipped with a 
stirrer, a thermometer and a dropping funnel and the mixture was heated to 
80.degree. C. Next, 175 g (1.07 moles) of eugenol was added dropwise to 
this system. Because heat was generated at this time, caution was taken so 
that the system did not exceed 100.degree. C. After the dropwise addition 
was completed, the system was heated and stirred for 30 minutes at 
100.degree. to 110.degree. C., after which it was heated to 130.degree. C. 
at 5 mmHg and the unreacted raw material was removed. The viscosity of the 
reaction product that was obtained was 80 centipoise at 25.degree. C. This 
reaction product was identified by Fourier transform-nuclear magnetic 
resonance spectrum analysis (FT-NMR) as dimethyl polysiloxane having 
eugenol residues in both terminals of the molecular chain as indicated by 
the following formula. 
##STR9## 
REFERENCE EXAMPLE 2 
Six hundred grams of dimethyl polysiloxane both terminals of the molecular 
chain of which were blocked by dimethylhydrogen siloxy groups (content of 
silicon atom bonded hydrogen atoms=0.017 wt %) as indicated by the formula 
##STR10## 
and 0.7 g of isopropyl alcohol solution of 2 wt % monochloroplatinic acid 
were introduced into a ne liter round-bottom flask equipped with a 
stirrer, a thermometer and a dropping funnel and the mixture was heated to 
80.degree. C. Next, 18.4 g (0.11 mol) of eugenol was added dropwise to 
this system as it was being stirred. Because heat was generated at this 
time, caution was taken so that the system did not exceed 100.degree. C. 
After the dropwise addition was completed, the system was heated and 
stirred for 30 minutes at 100.degree. to 110.degree. C., after which it 
was heated to 130.degree. C. at 5 mmHg and the unreacted raw material was 
removed. The viscosity of the reaction product that was obtained was 480 
centipoise at 25.degree. C. This reaction product was identified by FT-NMR 
as dimethyl polysiloxane having eugenol residues in both terminals of the 
molecular chain as indicated by the following formula: 
##STR11## 
REFERENCE EXAMPLE 3 
Six hundred grams of dimethyl siloxane-methylhydrogen siloxane copolymer 
(content of silicon atom bonded hydrogen atoms=0.1 wt %) of a viscosity of 
170 centipoise both terminals of the molecular chain of which were blocked 
by trimethylsiloxy groups as indicated by the formula 
##STR12## 
and 0.7 g of isopropyl alcohol solution of 2 wt % monochloroplatinic acid 
were introduced into a one liter round-bottom flask equipped with a 
stirrer, a thermometer and a dropping funnel and the mixture was heated to 
80.degree. C. Next, 108 g (0.66 mol) of eugenol was added dropwise to this 
system as it was being stirred. Because heat was generated at this time, 
caution was taken so that the system did not exceed 100.degree. C. After 
the dropwise addition was completed, the system was heated and stirred for 
30 minutes at 100.degree. to 110.degree. C., after which it was heated to 
130.degree. C. at 5 mmHg and the unreacted raw material was removed. The 
viscosity of the reaction product that was obtained was 600 centipoise at 
25.degree. C. This reaction product was identified by FT-NMR as an 
organopolysiloxane having eugenol residues in both terminals of the 
molecular chain as indicated by the following formula: 
##STR13## 
REFERENCE EXAMPLE 4 
Fifty grams of methyl siloxane-methylhydrogen siloxane copolymer (content 
of silicon atom bonded hydrogen atoms=1.6 wt %) both terminals of the 
molecular chain of which were blocked by trimethylsiloxy groups as 
indicated by the formula 
##STR14## 
and 0.05 g of isopropyl alcohol solution of 3 wt % monochloroplatinic acid 
6-hydrate were introduced into a one liter round-bottom flask equipped 
with a stirrer, a thermometer and a dropping funnel and the mixture was 
heated to 80.degree. C. Next, 340 g (0.87 mol) of an organic compound as 
indicated by the formula 
##STR15## 
were added dropwise to this system as it was being stirred. The system was 
then heated and stirred for 3 hours at 100.degree. C. Next, 50 g (0.45 
mol) of 1-octene was added dropwise to this system and the system was 
heated and stirred for 1 hour at 100.degree. C. Following this, the system 
was heated to 130.degree. C. at 10 mmHg and the unreacted raw material was 
removed. This reaction product was identified by FT-NMR as an 
organopolysiloxane having hindered phenol residues in both terminals of 
the molecular chain as indicated by the following formula. 
##STR16## 
REFERENCE EXAMPLE 5 
Six Hundred grams of dimethyl polysiloxane both terminals of the molecular 
chain of which were blocked by dimethylhydrodiene siloxy groups (content 
of silicon atom bonded hydrogen atoms=0.017 wt %) as indicated by the 
formula 
##STR17## 
and 0.7 g of isopropyl alcohol solution of 2 wt % monochloroplatinic acid 
were introduced into a one liter round-bottom flask equipped with a 
stirrer, a thermometer and a dropping funnel and the mixture was heated to 
80.degree. C. Next, 150 g (1.12 mol) of o-allylphenol was added dropwise 
to this system as it was being stirred. Because heat was generated at this 
time, caution was taken so that the system did not exceed 100.degree. C. 
After the dropwise addition was completed, the system was heated and 
stirred for 30 minutes at 100.degree. to 110.degree. C., after which it 
was heated to 130.degree. C. at 5 mmHg and the unreacted raw material was 
removed. The viscosity of the reaction product that was obtained was 80 
centipoise at 25.degree. C. This reaction product was identified by FT-NMR 
as dimethylpolysiloxane having phenol residues in both terminals of the 
molecular chain as indicated by the following formula. 
##STR18## 
EXAMPLE 1 
The dimethyl polysiloxane prepared in Reference Example 1 (0.3 parts by 
weight) was added as the heat resistant agent to 100 parts by weight of 
dimethyl polysiloxane having a viscosity of 10,000 centipoise both 
terminals of the molecular chain of which were blocked by trimethylsiloxy 
groups. The organopolysiloxane composition that was obtained was a 
homogeneous and transparent liquid. Thirty grams of this 
organopolysiloxane composition was introduced into a beaker the diameter 
of the bottom face of which was approximately 5 cm and the beaker was 
placed in an oven at 280.degree. C. The time required for viscosity to 
increase to twice the initial viscosity of this organopolysiloxane was 
defined as gelation time. This organopolysiloxane was subjected to 
thermogravimetric analysis and the weight decrease ratio was found. The 
results are shown in Table 1. 
EXAMPLE 2 
Three parts by weight of the dimethyl polysiloxane prepared in Reference 
Example 2 was added as the heat resistant agent to 100 parts by weight of 
dimethyl polysiloxane of a viscosity of 10,000 centipoise both terminals 
of the molecular chain of which were blocked by trimethylsiloxy groups. 
The organopolysiloxane composition that was obtained was a homogeneous and 
transparent liquid. Thirty grams of this organopolysiloxane composition 
was introduced into a beaker as in Example 1, and the gelation time 
determined. This organopolysiloxane was also subjected to 
thermogravimetric analysis and the weight decrease ratio was found. The 
results are shown in Table 1. 
EXAMPLE 3 
The organopolysiloxane prepared in Reference Example 3 (0.3 parts by 
weight) was added as the heat resistant agent to 100 parts by weight of 
dimethyl polysiloxane of a viscosity of 10,000 centipoise both terminals 
of the molecular chain of which were blocked by trimethylsiloxy groups. 
The organopolysiloxane composition that was obtained was a homogeneous and 
transparent liquid. Thirty grams of this organopolysiloxane composition 
was introduced into a beaker as in Example 1, and the gelation time was 
determined. The results are shown in Table 1. 
COMATIVE EXAMPLE 1 
The organopolysiloxane prepared in Reference Example 4 (3 parts by weight) 
was added as the heat resistant agent to 100 parts by weight of dimethyl 
polysiloxane of a viscosity of 10,000 centipoise both terminals of the 
molecular chain of which were blocked by trimethylsiloxy groups. The 
organopolysiloxane composition that was obtained was an opaque liquid 
(i.e., suspension.) Thirty grams of this organopolysiloxane composition 
was introduced into a beaker as in Example 1 and the gelation time was 
determined. The results are shown in Table 1. 
COMATIVE EXAMPLE 2 
The dimethyl polysiloxane prepared in Reference Example 5 (0.3 parts by 
weight) was added as the heat resistant agent to 100 parts by weight of 
dimethyl polysiloxane of a viscosity of 10,000 centipoise both terminals 
of the molecular chain of which were blocked by trimethylsiloxy groups. 
The organopolysiloxane composition that was obtained was a homogeneous and 
transparent liquid. Thirty grams of this organopolysiloxane composition 
was introduced into a beaker as in Example 1 and the gelation time was 
determined. This organopolysiloxane was subjected to thermogravimetric 
analysis and the weight decrease ratio was found. The results are shown in 
Table 1. 
COMATIVE EXAMPLE 3 
Thirty grams of dimethyl polysiloxane of a viscosity of 10,000 centipoise 
both terminals of the molecular chain of which were blocked by 
trimethylsiloxy groups was introduced into a beaker as in Example 1 and 
the gelation time was determined. This organopolysiloxane was subjected to 
thermogravimetric analysis and the weight decrease ratio was found. The 
results are shown in Table 1. 
TABLE 1 
______________________________________ 
Weight decrease ratio (*) (%) 
Group Gelation time 
350.degree. 
360.degree. 
370.degree. 
380.degree. 
390.degree. 
400.degree. 
Item (hours) C. C. C. C. C. C. 
______________________________________ 
Example 1 
58 0 2.2 4.3 5.7 6.5 7.4 
Example 2 
56 0 1.3 2.8 5.6 7.8 9.1 
Example 3 
55 -- -- -- -- -- -- 
Comparative 
14 -- -- -- -- -- -- 
Example 1 
Comparative 
13 1.7 3.0 5.0 7.0 12.1 17.0 
Example 2 
Comparative 
13 2.0 3.9 5.7 7.0 12.2 17.0 
Example 3 
______________________________________ 
(*) Rate of temperature elevation: Room temperature to 300.degree. C. at 
50.degree. C./minute and 300.degree. C. to 450.degree. C. at 5.degree. 
C./minute