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
2001-12-03
2004-03-16
Mullis, Jeffrey (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S096000
Reexamination Certificate
active
06706813
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a curable composition suited for use as a rubbery material, for example a tire, a sealant, a gasket, an adhesive, a pressure sensitive adhesive or a damping material, and to a method of use thereof.
BACKGROUND ART
Block copolymers containing polymer blocks comprising aliphatic hydrocarbon compounds are inexpensive and are used as thermoplastic resins having good workability in a wide range of application. In particular, block copolymers composed of a polymer block of an aliphatic hydrocarbon compound and a styrenic polymer block easily melt upon heating and therefore are used as thermoplastic elastomers having good workability for gaskets, sealants, adhesives or pressure sensitive adhesives, damping materials and so forth.
However, in the case of block copolymers containing a polymer block comprising an aliphatic hydrocarbon compound, in particular block copolymers composed of a polymer block of an aliphatic hydrocarbon compound and a styrenic polymer block, characteristics such as mechanical properties and viscosity upon melting with heating depend on the ratio between the higher Tg segment and lower Tg segment of a thermoplastic elastomer and molecular weight of each segment and, therefore, there arises the problem that attempts to improve the workability in the step of melting turn into marked reductions in physical properties at high temperatures.
In view of the above-mentioned state of the art, it is an object of the invention to mitigate the reductions in physical properties at high temperatures of block copolymers having at least one block species formed from an aliphatic hydrocarbon compound(s).
DISCLOSURE OF INVENTION
As a result of investigations, the present inventors found that the above object can be accomplished by formulating a curable composition comprising (A) a block copolymer having at least one kind of block formed from an aliphatic hydrocarbon compound and (B) an isobutylene polymer having a silicon group bound to a hydrolyzable group or a hydroxyl group.
The present invention is thus directed to a curable composition
which comprises (A) a block copolymer having at least one kind of block formed from an aliphatic hydrocarbon compound
and (B) an isobutylene polymer having a silicon group bound to a hydrolyzable group or a hydroxyl group.
The invention is also directed to a sealant comprising the above curable composition, an adhesive comprising the above curable composition, a pressure sensitive adhesive comprising the above curable composition, a composition for a gasket comprising the above curable composition and a double layer glazing spacer comprising the above curable composition.
The invention is further directed to a method of application for applying or molding the above curable composition in a state dissolved in a solvent, a method of application for applying or molding the above curable composition under heating condition, and a method of using which comprises allowing the condensation reaction of the (B) component to proceed with water after applying or molding the above curable composition.
In the following, the present invention is described in detail.
The block copolymer (A) having at least one block species formed from an aliphatic hydrocarbon compound to be used in accordance with the invention is first described.
The aliphatic hydrocarbon compound is not particularly restricted but may be any of those capable of forming polymers. Thus it includes, for example, ethylene, propylene, 1-butene, isobutylene, butadiene and isoprene. These may be used singly or a plurality thereof may be used in combination. These polymers may be used after hydrogenation thereof.
The block formed from an aliphatic hydrocarbon compound (hereinafter sometimes referred to as “aliphatic hydrocarbon block”) in the (A) component is not particularly restricted. Relatively flexible blocks can be obtained by (1) homopolymerizing a diene compound such as butadiene or isoprene, (2) polymerizing the diene compound as mentioned above followed by hydrogenating the polymer, (3) polymerizing an olefin compound containing 1 to 6 carbon atoms, such as ethylene, propylene, 1-butene or isobutylene, as a main monomer, or (4) copolymerizing the above olefin compound and the diene compound and, using the polymer as it is or followed by hydrogenating the polymer. As relatively rigid aliphatic hydrocarbon blocks, there may be mentioned, as examples, crystalline blocks, specifically polyethylene blocks and polyhexene blocks.
The block other than the aliphatic hydrocarbon block in the (A) component is not particularly restricted but may be any of those capable of forming block copolymers with the aliphatic hydrocarbon block. Thus, it includes, for example, blocks of a vinyl aromatic compound or a nitrile compound, more specifically, blocks comprising styrene, &agr;-methylstyrene or acrylonitrile.
In the practice of the invention, block copolymers composed of a polymer block mainly comprising a vinyl aromatic compound and a polymer block mainly comprising an aliphatic hydrocarbon compound are preferred as the (A) component block copolymer. The term “a polymer block mainly comprising a compound” means that the monomer unit corresponding to that compound accounts for at least 60%, preferably at least 80%, of the monomer units constituting that polymer block.
The composition of the (A) component is not restricted so long as the composition can manifest the desired characteristics. From the viewpoint of availability or fluidity at high temperature, there may be mentioned block copolymers composed of a styrenic block and a butadiene and/or isoprene and/or isobutylene block, and hydrogenation products derived therefrom, more specifically, SBS (styrene-butadiene-styrene block copolymers), SIS (styrene-isoprene-styrene block copolymers), SEBS (styrene-ethylenebutylene-styrene block copolymers), SEPS (styrene-ethylenepropylene-styrene block copolymers), SIBS (styrene-isobutylene-styrene block copolymers) and the like.
In the (A) component block copolymer, the ratio between the aliphatic hydrocarbon block content and the content of blocks other than the aliphatic hydrocarbon block is not particularly restricted. From the viewpoint of the balance between fluidity and physical properties, however, the ratio is preferably 5/95 to 95/5, more preferably 10/90 to 60/40, on the weight basis. The block structure may be straight-chained or have a side chain.
The number average molecular weight of the (A) component block copolymer is not particularly restricted but, generally, it is about 500 to 1,000,000, preferably about 1,000 to 100,000.
The isobutylene polymer having a silicon group bound to a hydrolyzable group or a hydroxyl group, namely the (B) component to be used in accordance with the invention, is now described. The term “a silicon group bound to a hydrolyzable group or a hydroxyl group” so referred to herein means a group having an Si—X bond in the case that X represents a hydrolyzable group or a hydroxyl group, for instance. Upon hydrolysis reaction, the Si—X bond generally gives Si—OH and H—X.
The silicon group which the (B) component isobutylene polymer has is a functional group well known in the art. As typical examples thereof, there may be mentioned a group represented by the general formula (1):
—(SiR
1
2-b
X
b
O)
m
—SiR
2
3-a
X
a
(1)
in the formula, R
1
and R
2
each is an alkyl group containing 1 to 20 carbon atoms, an aryl group containing 6 to 20 carbon atoms, an aralkyl group containing 7 to 20 carbon atoms or a triorganosiloxy group represented by R
3
3
SiO— (in which R
3
is a univalent hydrocarbon group containing 1 to 20 carbon atoms and the three R
3
groups may be the same or different); when there are two or more R
1
or R
2
groups, they maybe the same or different; X is a hydrolyzable group or a hydroxyl group and, when there are two or more X groups, they may be the same or different; a is an integer selected from among 0 to 3, b is an integer selected from among 0 to 2, provided that the relation a+mb≧1 i
Chiba Makoto
Komitsu Shintaro
Kaneka Corporation
Mullis Jeffrey
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