Polymer and process for producing polymer

Details Polymer and process for producing polymer Polymer and process for producing polymer

2000-11-20

2003-11-18

Seidleck, James J. (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...

C525S284000, C525S298000, C525S301000, C525S313000, C525S319000, C526S090000

Reexamination Certificate

active

06649701

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a polymer of a radical-polymerizable olefin monomer and a method of producing the same.
BACKGROUND ART
The art of coupling polymer extension ends to produce a long-chain polymer is known. In the case of anionic polymerization, coupling can be effected by adding a compound having two electrophilic functional groups. In the case of cationic polymerization, coupling can be effected by adding a compound having two nucleophilic functional groups.
Meanwhile, it is known that a polymer having a terminal functional group crosslinks by itself or in the presence of a suitable curing agent to give a cured product of high heat resistance and durability. Typical of the polymer of this kind has a terminal hydroxyl or crosslinkable silyl group. The hydroxy-terminated polymer can be crosslinked and cured by using a polyfunctional isocyanate compound as the curing agent. The crosslinkable silyl-terminated polymer gives a cured product by absorbing moisture in the presence of a suitable condensation catalyst.
The backbone skeleton of such a polymer having a terminal hydroxyl or crosslinkable silyl group may for example comprise a polyether polymer such as polyethylene oxide, polypropylene oxide, polytetramethylene oxide or the like, a hydrocarbon polymer such as polybutadiene, polyisoprene, polychloroprene, polyisobutylene or the like inclusive of the hydrogenation product thereof, or a polyester polymer such as polyethylene terephthalate, polybutylene terephthalate, polycaprolactone or the like. Depending on the backbone skeletal structure and the mode of crosslinking, those polymers have been used in various applications.
The art of coupling the molecular ends of vinyl polymers obtainable by radical polymerization, as contrasted to said coupling by ionic polymerization or polycondensation, has not been fully established on a commercial scale as yet. Unlike in ionic polymerization, the direct coupling of radicals at the polymer propagation end is theoretically feasible in radical polymerization but because the radical polymerization reaction itself may be controlled only with considerable difficulty, it is not easy to control the coupling reaction.
Among vinyl polymers, (meth)acrylic polymers have certain characteristics, such as high weathering resistance and high clarity, which are not found in said polyether, hydrocarbon and polyester polymers. Particularly (meth)acrylic polymers having an alkenyl or crosslinkable silyl group in the side chain have been utilized in super-weather-resistant paints. Nevertheless, control of polymerization in the case of acrylic polymers is not easy owing to side reactions involved and, as a corollary, the coupling of polymer propagation ends is extremely difficult.
As advantages of the coupling reaction, there can be mentioned the increase in molecular weight by chain extension, the synthesis of block copolymers, and the synthesis of polymers having terminal functional groups. As coupling occurs, the molecular weight is increased two-fold in the case of a polymer having one propagation end and theoretically infinitely when the polymer has two propagation ends. When a diblock copolymer synthesized by serial addition of monomers is caused to undergo coupling, an ABA triblock copolymer is synthesized. In the case of a polymer that is polymerized using a functional group-containing initiator, coupling of propagation ends yields a polymer having a functional group at both terminals.
Compared with a vinyl polymer having a crosslinkable functional group in the side chain, a vinyl polymer having a crosslinkable functional group at both terminals yields a cured product with superior physical properties. Therefore, many workers have been exploring for an expedient technology for producing such polymers but it is not easy to produce them on a commercial scale. Japanese Kokai Publication Hei-5-255415 discloses a process for producing a (meth)acrylic polymer having an alkenyl group at both terminals which is characterized in that an alkenyl group-containing disulfide is used as the chain transfer agent. Japanese Kokai Publication Hei-5-262808 discloses a process which comprises synthesizing a (meth)acrylic polymer having a hydroxyl group at both terminals by using a hydroxyl group-containing disulfide and, by exploiting the reactivity of hydroxyl groups, synthesizing a (meth)acrylic polymer having an alkenyl group at both terminals. However, these processes are not easily amenable to polymer molecular weight control. Furthermore, in order that a functional group may be certainly introduced into every terminal position, the chain transfer agent must be used in a large amount so that said processes are not fully satisfactory in terms of process control.
SUMMARY OF THE INVENTION
In view of the above state of the art, the present invention has for its object to provide a polymer available upon coupling of polymers of radical-polymerizable olefin monomer or monomers and a process for producing said polymer.
The present invention, therefore, is concerned with a method for effecting polymer-polymer coupling in the living radical polymerization of a radical-polymerizable olefin monomer
which comprises adding a compound having at least two sparingly radical-polymerizable alkenyl groups during or after polymerization.
The compound having at least two sparingly radical-polymerizable alkenyl groups to be thus added is preferably a compound of the general formula (1):
wherein R
1
represents a divalent or polyvalent saturated hydrocarbon group of 1 to 20 carbon atoms or a group represented by the following general formula (2):
wherein R
4
represents an oxygen atom, a nitrogen atom or a divalent or polyvalent organic group containing 1 to 20 carbon atoms; R
5
represents a hydrogen atom or a methyl group; 4 R
5
s may be the same or different; R
2
and R
3
are the same or different and each represents a hydrogen atom or a methyl group.
The more preferred is a compound of the general formula (1)
wherein R
1
is preferably an alkylene group of 1 to 20 carbon atoms,
and still more preferred is a compound of the general formula (3):
 wherein n represents an integer of 1 to 20.
As specific examples, 1,5-hexadiene, 1,7-octadiene and 1,9-decadiene can be mentioned.
The living radical polymerization in the present invention is preferably atom transfer radical polymerization.
The catalyst for atom transfer radical polymerization preferably comprises a metal complex, said metal complex having the central metal selected from an element belonging to the group 7, 8, 9, 10 or 11 of the periodic table of the elements, more preferably a complex of a metal selected from the group consisting of copper, nickel, ruthenium and iron, particularly a copper complex.
The radical-polymerizable olefin monomer for use in the present invention is preferably an &agr;, &bgr;-unsaturated carboxylic acid series monomer, more preferably a (meth)acrylic monomer, still more preferably an acrylic monomer, still more preferably an acrylate monomer, and most preferably butyl acrylate.
The initiator for atom transfer radical polymerization is preferably a functional group-containing organohalogen compound or a functional group-containing halosulfonyl compound, where the functional group is preferably a hydroxyl group or a hydrolyzable silyl group.
The present invention is further concerned with a polymer as obtainable by the method of the present invention.
The polymer as obtainable by the present invention is not particularly restricted but is preferably a polymer having a group of the general formula (4):
wherein R
1
represents a divalent or polyvalent saturated hydrocarbon group containing 1 to 20 carbon atoms or a group of the general formula (5):
wherein R
4
represents an oxygen atom, a nitrogen atom, or a divalent or polyvalent organic group containing 1 to 20 carbon atoms; R
5
represents a hydrogen atom or a methyl group, and 4 R
5
s may be the same or different; R
2
and R
3
are the same or different and each represents a hydrogen atom or a methyl group;

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