Curable fluoropolyether rubber compositions

Details Curable fluoropolyether rubber compositions Curable fluoropolyether rubber compositions

2001-07-10

2003-03-04

Dawson, Robert (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S252000, C524S255000, C524S258000, C524S323000, C524S333000, C524S345000, C524S349000, C528S015000, C528S025000, C528S031000, C528S042000, C528S402000

Reexamination Certificate

active

06528562

ABSTRACT:

This invention relates to a curable fluoropolyether rubber composition which cures into products having heat resistance, chemical resistance, solvent resistance, parting property, water repellency, oil repellency, and weather resistance as well as resistance to acid, alkali and oxidative degradation.
BACKGROUND OF THE INVENTION
Japanese Patent No. 2,990,646 discloses a composition comprising a linear fluoropolyether compound containing at least two alkenyl groups per molecule and having a perfluoropolyether structure in its backbone, an organosilicon compound having at least two H—SiOSi structures per molecule, and a hydrosilylation catalyst. This composition cures into products having a good profile of heat resistance, chemical resistance, solvent resistance, parting property, water repellency, oil repellency, and weather resistance.
Although such fluoropolyether rubber compositions exhibit satisfactory performance in most applications, more acid resistance is required in semiconductor and engine oil-related applications.
SUMMARY OF THE INVENTION
An object of the invention is to provide a curable fluoropolyether rubber composition which cures into products having heat resistance, chemical resistance, solvent resistance, parting property, water repellency, oil repellency, and weather resistance as well as resistance to acid, alkali and oxidative degradation.
We have found that a fluoropolyether rubber composition obtained by blending (A) a linear fluoropolyether compound containing at least two alkenyl groups and having a perfluoroalkyl ether structure in its backbone, (B) an organosilicon compound having at least two silicon atom-bound hydrogen atoms which all form H—Si(C
a
H
2a
)Si structures, (C) a hydrosilylation catalyst, and (D) an antidegradant is curable into products having heat resistance, chemical resistance, solvent resistance, parting property, water repellency, oil repellency, and weather resistance as well as resistance to acid, alkali and oxidative degradation.
The invention provides a curable fluoropolyether rubber composition comprising
(A) a linear fluoropolyether compound containing at least two alkenyl groups in a molecule and having a perfluoroalkyl ether structure in its backbone,
(B) an organosilicon compound having at least two hydrogen atoms each bound to a silicon atom in a molecule, all the silicon atom-bound hydrogen atoms constituting a H—Si(C
a
H
2a
)Si structure wherein “a” is an integer of 1 to 3,
(C) a hydrosilylation catalyst, and
(D) an antidegradant.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The respective components of the curable fluoropolyether rubber composition are described below.
The linear fluoropolyether compound (A) used herein is one containing at least two alkenyl groups in a molecule and having a divalent perfluoroalkyl ether structure in its backbone.
The perfluoroalkyl ether structure is a structure containing a plurality of recurring units of the formula: —C
d
F
2d
O— wherein d is independently on each occurrence an integer of 1 to 6. Typical structure has the following general formula (5):
(C
d
F
2d
O)
q
  (5)
wherein q is an integer of 1 to 500, preferably 2 to 400, more preferably 10 to 200.
Examples of the recurring units of formula (5) are shown below.
—CF
2
O—, —CF
2
CF
2
O—, —CF
2
CF
2
CF
2
O—,
—CH(CF
3
)CF
2
O—, —CF
2
CF
2
CF
2
CF
2
O—,
—CF
2
CF
2
CF
2
CF
2
CF
2
CF
2
O—, and —C(CF
3
)
2
O—.
Of these, —CF
2
O—, —CF
2
CF
2
O—, —CF
2
CF
2
CF
2
O—, and —CH(CF
3
)CF
2
O— are preferred. It is understood that the perfluoroalkyl ether structure may consist of recurring units of one type or recurring units of two or more types.
The alkenyl groups in the linear fluoropolyether compound are those of 2 to 8 carbon atoms, especially 2 to 6 carbon atoms, having a CH
2
═CH— structure at an end such as vinyl, allyl, propenyl, isopropenyl, butenyl and hexenyl, with the vinyl and allyl being especially preferred. The alkenyl groups may be present within the molecule, although they are preferably attached to both ends of the molecular chain. In the preferred case, the alkenyl groups may be attached either directly to both ends of the backbone of the linear fluoropolyether compound or to the backbone through a divalent linking group such as
—CH
2
—, —CH
2
O— or —Y—NR′—CO—.
Herein Y is —CH
2
— or a group of the following structural formula (I):
(the bond may be at o, m or p-position) and R′ is hydrogen, methyl, phenyl or allyl.
Preferred linear fluoropolyether compounds (A) are those of the following general formula (1) or (2).
CH
2
═CH—(X)
p
—Rf′—(X)
p
—CH═CH
2
  (1)
CH
2
═CH—(X)
p
—Q—Rf′—Q—(X)
p
—CH═CH
2
  (2)
Herein X is independently —CH
2
—, —CH
2
O— or —Y—NR′—CO— wherein Y is —CH
2
— or a group of the following structural formula (I):
(the bond may be at o, m or p-position) and R′ is hydrogen, methyl, phenyl or allyl. Q is a divalent hydrocarbon group having 1 to 15 carbon atoms, which may contain an ether bond. Rf′ is a divalent perfluoroalkylene or perfluorooxyalkylene group, and p is independently equal to 0 or 1.
Of these, fluoropolyether compounds of the following general formula (3) are especially preferred.
Herein X is as defined above, p is independently equal to 0 or 1, r is an integer of 2 to 6, u is an integer of 1 to 6, and m and n each are an integer of 0 to 200.
The linear fluoropolyether compound of formula (3) desirably has a weight average molecular weight of about 400 to about 100,000, and especially about 1,000 to about 50,000.
Illustrative examples of the fluoropolyether compound of formula (3) are given below. In the following formulae, m and n are as defined above.
It is sometimes preferred to adjust the linear fluoropolyether compound to a desired weight average molecular weight for a particular application. In this case, a linear fluoropolyether compound is subjected to hydrosilylation reaction with an organosilicon compound having two SiH groups in a molecule by a conventional method under ordinary conditions to give a chain-lengthened product, which can be used as component (A).
The organosilicon compound (B) functions as a crosslinker and chain extender for component (A). Any organosilicon compound is useful as long as it has at least two hydrogen atoms each bound to a silicon atom in a molecule, all the silicon atom-bound hydrogen atoms forming H—Si(C
a
H
2a
)Si structures wherein “a” is an integer of 1 to 3. Typical organosilicon compounds have the following general formula (4).
Herein R which may be the same or different is a monovalent hydrocarbon group having 1 to 20 carbon atoms. Z is hydrogen or a mono- or divalent group of the formula: —R, —M, —Q—Rf, —Q—, —Rf′— or —Q—Rf′—Q— wherein Q is a divalent hydrocarbon group having 1 to 15 carbon atoms, which may contain an ether bond, amide bond or carbonyl bond, Rf is a monovalent perfluoroalkyl or perfluorooxyalkyl group, and Rf′ is a divalent perfluoroalkylene or perfluorooxyalkylene group. The subscripts “s” and “t” each are 1, 2 or 3, “b” and “c” each are 0 or 1, “b” and “c” are not 0 at the same time, and “a” is 1, 2 or 3.
Examples of the monovalent hydrocarbon group represented by R include alkyl groups such as methyl, ethyl and propyl and aryl groups such as phenyl, although the detail of R will be described later. Examples of the divalent hydrocarbon group represented by Q include alkylene groups such as methylene, ethylene, propylene, tetramethylene, and hexamethylene, arylene groups such as phenylene, and combinations of alkylene groups with arylene groups. These groups may contain ether, amide and carbonyl bonds.
Z is either a monovalent group (such as —H, —R, —M, or —Q—Rf) or a divalent group (such as —Q—, —Rf′— or —Q—Rf′—Q—), which depends on the values of b and c.
Illustrative examples of the organosilicon compound of formula (4) are given below. In the following formulae, Me is methyl.
Note that “a” is an integer of 1 to 3 and k is an integer of 1 to 8.
With the compatibility with and dispersibility in comp

Affiliated with

Also associated with

Rating

Curable fluoropolyether rubber compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Curable fluoropolyether rubber compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Curable fluoropolyether rubber compositions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3007308