Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-02-09
2003-11-25
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S090000, C526S328000, C526S346000, C526S307100, C526S319000, C525S330300, C525S153000, C525S154000, C525S190000, C525S326100, C525S329700
Reexamination Certificate
active
06653429
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the reaction of the terminal halogen atom of a vinyl polymer having a specific structure with a carboxylic acid group.
BACKGROUND ART
To produce long-chain polymers by coupling growing terminals of polymers to each other is known in the art. In the case of anion polymerization, such coupling can be effected by adding a compound having two electrophilic functional groups. In the case of cation polymerization, the coupling can be effected in the same manner by adding a compound having two nucleophilic functional groups.
On the other hand, it is known that polymers having a terminal functional group, either alone or in combination with an appropriate curing agent, can be crosslinked to give cured products excellent in heat resistance and durability. Among others, hydroxy- or crosslinkable silyl-terminated polymers are typical examples. Hydroxy-terminated polymers can be crosslinked and cured by using a polyfunctional isocyanate compound as a curing agent. Crosslinkable silyl-terminated polymers absorb moisture in the presence of an appropriate condensation catalyst, to give cured products.
As the main chain skeleton of such hydroxy- or crosslinkable silyl-terminated polymers, there may be mentioned polyether polymers such as polyethylene oxide, polypropylene oxide and polytetramethylene oxide, hydrocarbon polymers such as polybutadiene, polyisoprene, polychloroprene and polyisobutylene, and hydrogenation products derived therefrom, and polyester polymers such as polyethylene terephthalate, polybutylene terephthalate and polycaprolactone, among others. These polymers are used for various purposes according to the main chain skeleton and the mode of crosslinking.
In contrast to the coupling reaction relevant to those polymers obtainable by ionic polymerization or polycondensation, the art of coupling together the termini of vinyl polymers obtainable by radical polymerization has scarcely been put to practical use. In the case of radical polymerization as contrasted to ionic polymerization, although it is possible theoretically to directly couple together radicals which are growing termini, because the radical polymerization reaction itself cannot be easily controlled and, hence, the coupling reaction is hardly controllable.
Among vinyl polymers, (meth)acrylic polymers have high weathering resistance, transparency and other characteristics, which cannot be expected of the above-mentioned polyether polymers, hydrocarbon polymers or polyester polymers. Among others, (meth)acrylic polymers having alkenyl or crosslinking silyl groups on side chains are used in high weathering resistance coatings and the like. On the other hand, it is not easy to control the polymerization of acrylic polymers due to side reactions and it is very difficult to couple growing termini thereof.
As the advantages of such a crosslinking reaction, there may be mentioned the increase in molecular weight as resulting from chain extension and the possibility of synthesizing block copolymers and of synthesizing functional group-terminated polymers, among others. Upon coupling, the molecular weight of a polymer having one growing terminus is doubled and, theoretically, that of a polymer having two growing termini is indefinitely increased. Upon coupling of a diblock copolymer synthesized by sequential addition of monomers, a triblock copolymer of type ABA is synthesized. In the case of a polymer as polymerized using a functional group-containing initiator, coupling of growing termini gives a polymer having the functional groups at both termini.
Vinyl polymers having crosslinking functional groups at both termini give cured products having superior physical characteristics as compared with those having crosslinking functional groups in side chains. Therefore, a number of workers have so far made investigations to find out a simple and easy method of producing the same. However, it is still not easy to produce them on an industrial scale. In Japanese Kokai Publication Hei-05-255415, there is disclosed a method of synthesizing (meth)acrylic polymers having alkenyl groups at both termini which comprise using an alkenyl-containing disulfide as a chain transfer agent. Japanese Kokai Publication Hei-5-262808 discloses a process for synthesizing a (meth)acrylic polymer having alkenyl groups at both termini which comprises synthesizing a (meth)acrylic polymer having hydroxyl groups at both termini using a hydroxy-containing disulfide and, taking advantage of the reactivity of said hydroxyl group, introducing alkenyl groups at both termini. However, it is not easy to control the molecular weight of the polymer in these methods. Further, for terminally introducing an alkenyl group with certainty, the use of a chain transfer agent in a substantial amount is essential, which raises a problem from production process points of view, however.
Furthermore, since these methods use ordinary radical polymerization techniques, it is not easy to control the molecular weight and molecular weight distribution (ratio of number average molecular weight to weight average molecular weight) of the polymer to be obtained.
Among functional groups, the carboxyl group can react with various reactive groups such as hydroxy, amino and epoxide, hence is a functional group effective as a crosslinking group. The use of a functional group-containing chain transfer agent as a means for introducing a carboxyl group into a polymer terminus is known in the art. Japanese Kokai Publication Hei-08-208759 and JP 1603919, for instance, disclose a technology for synthesizing carboxyl-terminated (meth)acrylic polymers using a mercaptocarboxylic acid as the chain transfer agent.
Meanwhile, graft copolymers are used as functional materials in various fields. For synthesizing graft copolymers with vinyl polymers as branching polymers, some methods are known. Thus, for example, a method of polymerization is known which comprises causing polymer branches to grow by polymerizing a monomer from polymerization initiation sites on a stem polymer (synthetic method 1). Another comprises using a polymer (macromonomer) having a terminal polymerizable double bond as a branch polymer and synthesizing a stem polymer later by homopolymerizing the macromonomer or copolymerizing the same with another vinyl monomer (synthetic method 2). According to synthetic method 1, radicals are formed on a stem polymer by utilizing a radical generator such as benzoyl peroxide or by irradiation of radiation and causing the polymerization of a branch polymer-constituting vinyl monomer to initiate from those radicals. Though it is simple and easy, synthetic method 1 cannot be free from side reactions, such as formation of homopolymers of the vinyl monomer used and/or decomposition of the stem polymer. As for synthetic method 2, it has the advantage that a graft copolymer having a definite structure can be obtained since the branch polymer is synthesized in advance. However, it is not easy to synthesize macromonomers, and only limited macromonomer species can be used.
On the other hand, a coupling method which comprises synthesizing a functional group-terminated branch polymer beforehand and coupling the branch polymer to a stem polymer utilizing the reactivity of the functional group (synthetic method 3) is also known. As the functional group-terminated branch polymer, there may be mentioned, for example, the polymer comprising the main chain skeleton as follows: thus, polyether polymers such as polyethylene oxide, polypropylene oxide and polytetramethylene oxide, hydrocarbon polymers such as polybutadiene, polyisoprene, polychloroprene, polyisobutylene and hydrogenation products derived from these, and polyester polymers such as polyethylene terephthalate, polybutylene terephthalate and polycaprolactone.
It is an object of the present invention to provide a method of coupling vinyl polymers, a method of terminal functional group introduction, a method of producing graft polymers, an improved method for carrying out such a reaction, and polymers produc
Fujita Masayuki
Kitano Kenichi
Nakagawa Yoshiki
Connolly Bove Lodge & Hutz
Kaneka Corporation
Zalukaeva Tatyana
LandOfFree
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