Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-02-19
2004-06-01
Lipman, Bernard (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S331700, C525S332100, C525S342000
Reexamination Certificate
active
06743862
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to rubber compositions crosslinkable at room temperature and uses thereof. More particularly, the present invention relates to crosslinkable rubber compositions which enable high crosslinking rate at room temperature, efficient productivity to produce a crosslinked rubber molded product, and low-cost production of a crosslinked rubber molded product excellent in weather, ozone, heat aging and compression set resistances, and the uses thereof. The invention also relates to crosslinkable rubber compositions having excellent moldability and adhesion in addition to the above properties, which are thus suitable as a sealing material and the like, and uses of the compositions.
BACKGROUND OF THE INVENTION
Curing materials have been employed in sealing, coating, potting and bonding of items in industries involving electric and electronic parts or transport aircrafts, and in other industries, such as civil engineering and construction, medical and leisure industries.
An exemplary curing material is one (composition) comprising an organic polymer having a silicon-containing group which contains a hydroxyl group or a hydrolyzable group each bonded to a silicon atom and is crosslinkable by formation of a siloxane bond.
The curing material requires moisture at its curing and the curing takes a long time.
In order to solve the above problems, a composition has been developed wherein polyorganosiloxane having at least two vinyl groups on the average in one molecule is crosslinked with an organohydrogensiloxane having 2 or more hydrogen atoms bonded to a silicon atom in a molecule. The composition can be employed as the curing material for its excellent weather, water and heat resistances. However, the composition has defects such as high costs, poor adhesion, easy outbreak of fungus and unsatisfactory resistance to gas permeability, which limits therefore its applications.
A composition disclosed in Japanese Patent Application Laid-Open No.4(1992)-185687 solves the above problem. This composition comprises a compound having at least one alkenyl group in a molecule, a compound having at least two hydrosilyl groups in a molecule, a hydrosilylation catalyst, and a silane coupling agent. In the examples described in this publication, use was made of terminal-allyl group etherified polyoxypropylene, polypropyleneoxide having a hydrosilyl group, allyl-terminated polycaprolactam, polycaprolactam having cyclic hydrogenpolysiloxane, allyl-terminated polyisoprene, and hydrogenated polyisoprene having cyclic hydrogenpolysiloxane.
According to the present inventors' supplementary examination for the examples of the publication, admittedly shorten curing time and improved adhesion, but the curing rate, the weather resistance and the heat aging resistance remained unsatisfying. The adhesion still required further improvement.
The present inventors therefore made an earnest study on an ethylene/&agr;-olefin
on-conjugated polyene random copolymer rubber composition, and found that a rubber composition comprising an ethylene/&agr;-olefin
on-conjugated polyene random copolymer rubber (A), an SiH group-containing compound (B) containing at least two SiH groups in one molecule, and optionally, a catalyst (C), a reaction inhibitor (D), a silane coupling agent (E) and a plasticizer (F) enables high crosslinking rate at room temperature, efficient productivity to produce a crosslinked rubber molded product, and low-cost production of a crosslinked rubber molded product excellent in weather, ozone, heat aging and compression set resistances. Based on such findings, the present invention has been completed.
OBJECT OF THE INVENTION
The present invention has been made to solve the problems associated to the prior art, and an object of the present invention is to provide crosslinkable rubber compositions which enable high crosslinking rate at room temperature, efficient productivity to produce a crosslinked rubber molded product, and low-cost production of a crosslinked rubber molded product which is excellent in weather, ozone, heat aging and compression set resistances, and is attractive in terms of production costs. It is another object of the present invention to provide crosslinkable rubber compositions having excellent moldability and adhesion in addition to the above properties, which are thus suitable as a sealing material or the like. It is further object of the present invention to provide products which comprise the compositions, and are excellent in curing rate, weather resistance, heat aging resistance and adhesion, particularly with inorganic materials such as a metal, which products are clarified by sealing, potting and coating materials and an adhesive employed in industries involving electric and electronic parts or transportation machines, and in other industries, such as civil engineering and construction, medical and leisure industries.
SUMMARY OF THE INVENTION
The first crosslinkable rubber composition of the present invention is crosslinkable at room temperature (25° C.), has a gelation time at room temperature of 30 days or less, and has properties that a crosslinked rubber sheet obtained by crosslinking the composition at room temperature has a tensile elongation of 20% or more (JIS K-6251: measurement temperature 20° C.; tensile rate 500 mm/min) and has no crack after a treatment at 40° C. in a 50 pphm ozone concentration for 96 hr in accordance with an ozone deterioration test method defined in JIS K-5259.
The gelation time is determined as follows. The change in frequency was measured using a scanning VNC (SVNC) (manufactured by Rapra Technology Ltd.). The frequency increases with proceeding of this measurement, and when it stabilized, it was taken to be 100%. The time that the frequency changed 95% was taken as the gelation time (crosslinking time). The measuring temperature was room temperature and the measuring procedure was carried out according to the following literatures.
(i) RAPRA Operation manual (Software Ver. 2.2) of Scanning vibrating needle type curemeter (scanning VNC)
(ii) RAPRA Curing comprehension (RTL/2844) Scanning vibrating needle type curemeter (scanning VNC).
The second crosslinkable rubber composition according to the present invention comprises:
(A) an ethylene/&agr;-olefin
on-conjugated polyene random copolymer rubber having structural units derived from at least one norbornene compound having a vinyl group at the end, which is non-conjugated polyene, represented by the formula (I) or (II),
wherein n is an integer of 0 to 10,
R
1
is hydrogen or an alkyl group of 1 to 10 carbon atoms, and
R
2
is hydrogen or an alkyl group of 1 to 5 carbon atoms;
wherein R
3
is hydrogen or an alkyl group of 1 to 10 carbon atoms, and
(B) an SiH group-containing compound having at least two SiH groups in one molecule; and has
a gelation time at room temperature (25° C.) of 30 days or less.
The second crosslinkable rubber composition according to the present invention may comprise:
(A) an ethylene/&agr;-olefin
on-conjugated polyene random copolymer rubber,
(B) an SiH group-containing compound having at least two SiH groups in one molecule, and
(C) a catalyst,
or it may comprise:
(A) an ethylene/&agr;-olefin
on-conjugated polyene random copolymer rubber,
(B) an SiH group-containing compound having at least two SiH groups in one molecule,
(C) a catalyst, and
(D) a reaction inhibitor and/or
(E) a silane coupling agent.
The second crosslinkable rubber composition may further comprise a plasticizer (F) in an amount of 1 to 1,000 parts by weight based on 100 parts by weight of the ethylene/&agr;-olefin
on-conjugated polyene random copolymer rubber (A). The above amount of plasticizer (F) is preferable when the ethylene/&agr;-olefin
on-conjugated polyene random copolymer rubber (A) has the following properties (i) to (v).
The ethylene/&agr;-olefin
on-conjugated polyene random copolymer rubber (A) has:
(i) a molar ratio of ethylene to an &agr;-olefin of 3 to 20 carbon atoms (ethylene/&agr;-olefin) of 40/60 to 95/5,
Arino Mitsunao
Hakuta Takashi
Kawasaki Masaaki
Kikuchi Yoshiharu
Burns Doane , Swecker, Mathis LLP
Lipman Bernard
Mitsui Chemicals Inc.
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