Room temperature curable polyether composition

A room temperature curable polyether composition, comprising a polyether compound of which at least one terminal has a group, represented by the general formula (1): ##STR1## wherein R.sup.1 is an alkyl group or an aryl group, R.sup.2 is a hydrogen atom or a monovalent organic group, R.sup.3 is a divalent organic group, X is a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxyl group, an alkenyloxy group, an acyloxy group, a ketoximate group, an amido group, an aminoxy group or a mercapto group and a is an integer of 0 to 2, and of which main chain comprises a fluorine-containing polyether chain, represented by the general formula (2): ##STR2## wherein R.sub.f is a perfluoro group, R.sup.4 is a divalent organic group, m is an integer of 4 or more and n is an integer of 0 or more. The cured product thereof is excellent in rubber properties and is useful as one-part or two-part type elastic sealant. Furthermore it provides an elastic sealant excellent in solvent-resistance, chemical resistance, water repellency, oil repellency, etc.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a room temperature curable polyether 
composition that can be cured readily with the atmospheric water vapor. 
2. Description of the Prior Art 
As a room temperature curable polyether composition, a composition 
comprising a silyl group-terminated polyether which can be cured to form a 
rubber at room temperatures is proposed in Japanese Pre-examination Patent 
Publication (KOKAI) No. 54-6097 (1979). However, conventional room 
temperature curable polyethers are poor in solvent-resistance, chemical 
resistance, water repellency, oil repellency and heat-resistance. 
SUMMARY OF THE INVENTION 
An objective of the present invention is to provide a room temperature 
curable polyether composition that is excellent in solvent-resistance, 
chemical resistance, water repellency, oil repellency and heat-resistance. 
The present invention provides a room temperature curable composition, 
comprising a polyether compound of which at least one terminal has a 
silicon-containing organic group represented by the general formula (1): 
##STR3## 
wherein R.sup.1 is an alkyl group having 1 to 12 carbon atoms or an aryl 
group having 6 to 12 carbon atoms, R.sup.2 is a hydrogen atom or a 
monovalent organic group having 1 to 20 carbon atoms, R.sup.3 is a 
divalent organic group having 1 to 20 carbon atoms, X is a hydrogen atom, 
a halogen atom, a hydroxyl group, an alkoxyl group, an alkenyloxy group, 
an acyloxy group, a ketoximate group, an amide group, an aminoxy group or 
a mercapto group, and a is an integer of 0 to 2, and of which backbone 
chain comprises a fluorine-containing polyether chain with a molecular 
weight of 500 to 50,000 represented by the general formula (2): 
##STR4## 
wherein R.sub.f is a perfluoroalkyl group having 1 to 12 carbon atoms, 
R.sup.4 is a divalent organic group having 1 to 20 carbon atoms, m is an 
integer of 4 or more and n is an integer of 0 or more. 
The room temperature curable polyether composition of the present invention 
is excellent in physical properties after curing and is useful to form a 
one-part or two-part elastic sealant. Furthermore, it has an advantage to 
provide an elastic sealant excellent in solvent-resistance, chemical 
resistance, water repellency, oil repellency, etc., because the polyether 
backbone chain has a perfluoroalkyl group in its side chains.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Terminal Group 
In the polyether compound as the main component of the composition of the 
present invention, a silicon-containing organic group, which is linked to 
at least one terminal of the fluorine-containing polyether backbone chain, 
is represented by the general formula (1): 
##STR5## 
wherein R.sup.1 is an alkyl group having 1 to 12 carbon atoms, such as 
methyl, ethyl or butyl, or an aryl group having 6 to 12 carbon atoms, such 
as phenyl, tolyl, xylyl or naphtyl, preferably a methyl group, R.sup.2 is 
a hydrogen atom or a monovalent organic group such as a methyl group, 
R.sup.3 is a divalent organic group such as --CH.sub.2 -- or --CH.sub.2 
CH.sub.2 --, X is a hydrogen atom, a halogen atom, a hydroxyl group, an 
alkoxyl group such as a methoxyl group, an ethoxyl group, a propoxyl 
group, a butoxyl group or methoxyethoxyl group, an alkenyloxy group such 
as a propenyloxy group or a isobutyloxy group, an acyloxy group such as an 
acetoxy group, a propionoxy group or a butyroxy group, a ketoximate group 
such as a methyl ethylketoximate group, an amido group, and aminoxy group 
or a mercapto group, preferably an alkoxyl group, an alkenyloxy group, an 
acyloxy group or a ketoximate group and a is an integer of 0 to 2. 
Backbone Chain 
A fluorine-containing polyether chain as a backbone chain is represented by 
the general formula (2): 
##STR6## 
wherein R.sub.f is a perfluoroalkyl group having 1 to 12 carbon atoms, 
preferably 1 to 8 carbon atoms and includes, for example, 
##STR7## 
R.sup.4 is a divalent organic group having 1 to 20 carbon atoms such as 
##STR8## 
m is an integer of 4 or more and n is an integer of 0 or more. And the 
molecular weight thereof ranges from 500 to 50,000, preferably 1,000 to 
20,000. When the molecular weight is less than 500, the physical 
properties after curing are considerably lowered. When its molecular 
weight is over 50,000, it is very inconvenient in handling due to its high 
viscosity. 
The polyether compound has a silicon-containing organic group at least at 
one terminal of the fluorine-containing polyether chain represented by the 
general formula (2) and especially it is desirable to have the 
silicon-containing organic groups in an amount of 70 to 100% on average 
based on the total terminals. 
The type of linkage between a silicon-containing organic group represented 
by the general formula (1), and a fluorine-containing polyether chain 
represented by the general formula (2), is not especially limited and the 
following linkages are listed up, for example; a single bond directly 
[Note: In this case, an ether bond --O-- is formed, owing to an oxygen 
atom existing at the terminal of the general formula (2). Hereinbelow, 
linkages including the terminal oxygen atom of the general formula (2) are 
indicated in Note in the same manner.], a carbonyl bond --CO-- [Note: An 
ester bond --CO--O-- is formed.], an --O--CO-- bond [Note: A carbonate 
bond --O--CO--O-- is formed.] and an amide bond --NH--CO-- [Note: A 
urethane bond --NH--CO--O-- is formed.]. 
Preparation of Polyether Compound 
The polyether compound used in the present invention is prepared, for 
example, as described below. 
Into at least one terminal of a fluorine-containing polyetherglycol 
represented by the general formula (3): 
##STR9## 
wherein R.sub.f, R.sup.4, m and n are as defined above, is introduced an 
unsaturated group represented by the general formula (4): 
##STR10## 
wherein R.sup.2 and R.sup.3 are defined as above. 
The fluorine-containing polyether, used in the present invention, is 
obtained, for example, as a polymer of fluorine-containing alkylene oxide, 
such as 
##STR11## 
or as a copolymer of such a fluorine-containing alkylene oxide with an 
alkylene oxide, such as ethylene oxide or propylene oxide. Said polymer or 
copolymer can be prepared in cation polymerization or anion 
polymerization, as generally known. Among them, it is preferable to use a 
fluorine-containing alkylene oxide polymer, prepared from trifluoropropene 
oxide and propylene oxide as main raw materials. 
In order to introduce an unsaturated group having the general formula (4) 
to a terminal of said fluorine-containing polyether glycol, specifically, 
the following methods can be used, for example: 
(A) At least one hydroxyl terminal group of the glycol having the general 
formula (3) is converted to an alkaline metal alcoholate by reacting it 
with an alkaline metal compound, such as alkaline metal hydroxide (e.g. 
sodium hydroxide) or alkaline metal hydride (e.g. sodium hydride). The 
obtained alcoholate is then reacted with an unsaturated halide, having the 
general formula (5): 
##STR12## 
wherein R.sup.2 and R.sup.3 are defined as above, and Y is a chlorine 
atom, a bromium atom or an iodine atom. Thus, an unsaturated group, 
represented by the general formula (4), is introduced by forming a single 
bond, a carbonyl bond or --O--CO-- bond [Note: an ether bond, an ester 
bond or a carbonate bond, respectively is formed] as a linkage group. 
(B) At least one hydroxyl terminal group of a glycol having the general 
formula (3) is reacted with an unsaturated isocyanate compound, 
represented by the following formula: 
##STR13## 
wherein R.sup.2 and R.sup.3 are defined as above. Thus, an amido bond 
[Note: a urethane bond is formed] is formed as a linkage group to 
introduce an unsaturated group, represented by the general formula (4), to 
a terminal of said glycol. 
(C) At least one hydroxyl terminal group of the glycol having the general 
formula (3) is reacted with an unsaturated acid halide, ester or 
carboxylic acid represented by the general formula (6): 
##STR14## 
wherein R.sup.2 and R.sup.3 are as defined above and Q stands for a 
halogen atom, such as chlorine, bromine or iodine, an alkoxyl group or a 
hydroxyl group. Thus, a carbonyl bond [Note: an ester linkage] is formed 
as a linkage group to give a polyether compound of which 
fluorine-containing polyether chain having the general formula (2) is 
linked to an unsaturated group having the general formula (4). 
Thus obtained fluorine-containing polyether, to the terminal of which an 
unsaturated group has been introduced, is then made to react in the 
presence of a platinum catalyst with a silane compound represented by the 
general formula (7): 
##STR15## 
wherein R.sup.1, X and a are as defined above, so that said silane 
compound is added to the unsaturated terminal group of the 
fluorine-containing polyether to obtain the desired polyether compound. 
Examples of the silane compound, represented by the general formula (7), 
include halo silanes such as trichloro silane and methyldichlorosilane, 
alkoxysilanes such as trimethoxysilane, triethoxysilane and 
methyldimethoxysilane, acyloxysilanes such as methyldiacetoxysilane and 
phenyldiacetoxysilane, and ketoximesilanes such as 
bis(dimethylketoxime)methylsilane and bis(cyclohexylketoxime)methylsilane. 
Among these, alkoxysilanes are especially preferable. 
Other Components 
The composition of the present invention comprises the said polyether 
compound as an essential component. By exposing it to the atmosphere, its 
crosslinking reaction proceeds by absorbing moisture in the atmosphere to 
give a cured rubber-like elastomer. 
Other various components can be optionally added to this composition. For 
example, the addition of a known curing catalyst can promote the 
above-mentioned crosslinking or curing reaction. Examples of the said 
catalysts include amine compounds, quaternary ammonium compounds, 
organometal compounds, titanium chelate compounds, guanidyl 
group-containing compounds, etc., and there is no particular limitation 
about the amount of their addition. Normally, they may be added in an 
amount of less than about 10 parts per 100 parts of said polyether 
compound. 
Furthermore, for the purpose of adjusting properties of the objective 
rubber-like elastomer, the following inorganic fillers can be optionally 
added: known powder fillers, such as fumed silica, precipitated silica, 
titanium dioxide, aluminum oxide, quartz powder, talc and bentonite, 
asbestos and glass fiber. The amount of inorganic fillers is preferably 
1-500 parts, more preferably 10-300 parts, per 100 parts of said polyether 
compound. Fibrous fillers like organic fibers may be added. Oil-resistance 
improvers such as potassium methacrylate, colorants, heat-resistance 
improvers such as red oxide and cerium oxide, cold-resistance improvers, 
thixotropy improvers such as polyether dehydrating agents, and adhesive 
improvers such as .gamma.-aminopropyltriethoxysilane may be optionally 
added. Desired amounts of these additives may be added as required. 
Uses 
The composition of the present invention is useful as one-part or two-part 
type elastic sealants and also as sealants, coating agents and adhesives 
in the fields of building construction industry, machine industry and 
electrical industry. Because the polyether compound, the main component of 
said composition, has a fluorine-containing polyether in the backbone 
chain, the composition is excellent in solvent-resistance, chemical 
resistance, surface characteristics such as water repellency, oil 
repellency and release property. Hence, it is useful as materials for 
casting rubber and pattern-taking, paints and release agents as well. 
Especially, it is excellent as non-staining sealants. 
EXAMPLES 
Examples of the present invention will now be described below, in which 
"part(s)" means "part(s) by weight." 
PREATION EXAMPLE 1 
Into a 1 liter 4-necked flask equipped with a stirrer, 200 g of a 
polytrifluoropropyleneglycol having an average molecular weight of 15,000 
were charged, and then it was added with 400 g of m-xylene hexafluoride 
and 4.1 g of triethylamine. While the inside temperature of the flask was 
kept at 20.degree.-30.degree. C., 4.7 g of an unsaturated group-containing 
carboxylic acid chloride, expressed by CH.sub.2 .dbd.CHCH.sub.2 CH.sub.2 
COC1, were added dropwise under agitation. After completion of the 
addition, agitation was continued at 25.degree. C. for 10 hours. After the 
completion of reaction, the hydrochlorate of triethylamine was removed by 
washing with water. After dehydration and then removal of volatiles under 
a reduced pressure, a fluorine-containing polyether having an unsaturated 
terminal group was obtained. 
A 500 ml 4-necked flask equipped with a stirrer was charged with 100 g of 
the fluorine-containing polyether having an unsaturated terminal group. It 
was then added with 200 g of m-xylene hexachloride and 0.01 g of an 
isopropyl alcohol solution containing 1% chloroplatinic acid and heated to 
80.degree. C. And then, 2.1 g of methyldimethoxysilane were added dropwise 
in the flask. After the completion of the addition, agitation was 
continued at 80.degree. C. for 8 hours. After the completion of the 
reaction and removal of volatiles under a reduced pressure, a 
fluorine-containing polyether compound having a silicon-containing 
terminal group was obtained, which had the (CH.sub.3 O).sub.2 
Si(CH.sub.3)(CH.sub.2).sub.4 CO-terminal group to in an amount of 91% 
based on the total terminal groups. 
EXAMPLE 1 
12 parts of a fumed silica with a specific surface of 150 m.sup.2/ g, of 
which surface had been treated with hexamethyldisilazane, and 1.5 parts of 
titanium dioxide were mixed with 100 parts of the fluorine-containing 
polyether compound having silicon-containing terminal groups, obtained in 
Preparation Example 1. After milling the mixture with a 3-roll mill, 0.1 
part of dibutyltindioctate was degassed and mixed with them in a state 
free from water to obtain a room temperature curable polyether 
composition. The composition was formed to a sheet 2 mm thick. Being kept 
in the atmosphere of 20.degree. C. and 55% R.H. for 7 days, the sheet was 
cured to be a rubber-like elastomer. The resulting sheet was measured for 
hardness, tensile strength and elongation, according to JIS C 2123. The 
results are given below. 
______________________________________ 
Hardness (JIS A*): 29 
Tensile strength (kgf/cm.sup.2): 
23 
Elongation (%): 380 
______________________________________ 
*Hardness measurement was carried out on a Type A spring hardness tester 
according to JIS K 6301 
PREATION EXAMPLE 2 
A one liter 4-necked flask equipped with a stirrer was charged with 200 g 
of polynonafluorohexene glycol having an average molecular weight of 
8,000, and was added with 400 g of m-xylene hexafluoride, 8.7 g of 
30%-NaOH aq. solution and 1.7 g of tetrabutylammonium hydrogensulfate. 
While the inside temperature of the flask was kept at 50.degree. C., 7.9 g 
of allyl bromide (CH.sub.2 .dbd.CHCH.sub.2 Br) were added dropwise under 
agitation. After the completion of the addition, agitation was continued 
at 50.degree. C. for 8 hours. After the completion of the reaction, the 
resulting product was washed with water and dehydrated and then volatiles 
were removed under a reduced pressure to obtain a fluorine-containing 
polyether having an unsaturated terminal group. 
A 500 ml 4-necked flask equipped with a stirrer was charged with the 
obtained fluorine-containing polyether having an unsaturated terminal 
group. It was then added with 200 g of m-xylenehexachloride and 0.02 g of 
an isopropyl alcohol solution containing 1% chloroplatinic acid, and was 
heated to 80.degree. C. Then, 6.0 g of trimethoxysilane were added 
dropwise. After the completion of the addition, agitation was continued at 
80.degree. C. for 8 hours. After the completion of the reaction and 
removal of volatiles under a reduced pressure, the fluorine-containing 
polyether compound having a silicon-containing terminal group was 
obtained, which had the (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.3 -terminal 
group in an amount of 93% based on the total terminal groups. 
EXAMPLE 2 
A rubber-like elastomer was obtained in the same manner as in Example 1 
except for using 100 parts of the fluorine-containing polyether compound 
having a silicon-containing terminal group obtained in Preparation Example 
2. The obtained rubber-like elastomer was measured for hardness, tensile 
strength and elongation in the same manner as in Example 1. The results 
are given below. 
______________________________________ 
Hardness (JIS A): 21 
Tensile strength (kgf/cm.sup.2): 
19 
Elongation (%): 410 
______________________________________ 
Tests 
The rubber-like elastomers obtained in Examples 1 and 2 were tested for 
solvent resistance, chemical resistance and water and oil repellencies. 
For comparison, a cured product of the composition described in Example 1 
of Japanese Pre-examination Patent Publication (KOKAI) No. 54-6097 (1979) 
was also tested as a control. 
Solvent Resistance: 
A specimen was dipped in a solvent shown in Table 1 at 25.degree. C. for 48 
hours. Thereafter, volume swell (%) was measured. The results are given in 
Table 1. 
TABLE 1 
______________________________________ 
(Volume swell, %) 
Example 1 Example 2 Control 
______________________________________ 
Toluene 22 10 83 
Acetone 75 35 156 
Methyl acetate 
54 30 122 
Isopropanol 30 15 46 
Methanol 5 4 15 
______________________________________ 
Chemical Resistance: 
A specimen was dipped in a solution shown in Table 2 at 25.degree. C. for 
45 hours. Thereafter volume change (%) was measured. The results are given 
in Table 2. 
TABLE 2 
______________________________________ 
(Volume change, %) 
Example 1 
Example 2 Control 
______________________________________ 
10% NaOH aq. solution 
1 0 18 
10% HCl aq. solution 
0 0 2 
10% HNO.sub.3 aq. solution 
0 0 8 
10% H.sub.2 SO.sub.4 aq. solution 
1 0 5 
______________________________________ 
Water Repellency and Oil Repellency: 
Contact angle formed between a specimen and a droplet of a pure water or a 
lubricating oil placed on the specimen was measured. The results are given 
in Table 3. 
TABLE 3 
______________________________________ 
(Contact angle, degree) 
Example 1 Example 2 Control 
______________________________________ 
Pure water 86 110 0 
Lubricating oil 
56 62 36 
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