| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | August 14, 2001 |
| PATENT TITLE |
Functional groups-terminated vinyl polymers |
| PATENT ABSTRACT | A vinyl polymer which has at least one terminal functional group per molecule and has a ratio of weight average molecular weight to number average molecular weight of less than 1.8 as determined by gel permeation chromatography, said terminal functional group being a crosslinking silyl group, an alkenyl group, or a hydroxyl group. Curable compositions containing this vinyl polymer is easy to handle. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | July 28, 1998 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A vinyl polymer which has 1.2 to 4 terminal functional group per molecule and has a ratio of weight average molecular weight to number average molecular weight of less than 1.8 as determined by gel permeation chromatography, said terminal functional group being-an alkenyl group of the general formula (3), (4), (5), (6), or (7) shown below H.sub.2 C.dbd.C(R.sup.4)--R.sup.5 -- (3) H.sub.2 C.dbd.C(R.sup.4)--R.sup.5 --O-- (4) H.sub.2 C.dbd.C(R.sup.4)--R.sup.5 --OC(O)-- (5) H.sub.2 C.dbd.C(R.sup.4)--R.sup.5 --C(O)O-- (6) H.sub.2 C.dbd.C(R.sup.4)--R.sup.5 --OC(O)O-- (7) wherein R.sup.4 represents a hydrogen atom or a methyl group and R.sup.5 represents a direct bond, or an alkylene group containing 1 to 20 carbon atoms, an arylene group containing 6 to 20 carbon atoms or an aralkylene group containing 7 to 20 carbon atoms, which may contain one or more ether bonds, with the proviso that R.sup.5 of the general formula (3) represents an alkylene group containing 1 to 20 carbon atoms, an arylene group containing 6 to 20 carbon atoms or an aralkylene group containing 7 to 20 carbon atoms, which may contain one or more ether bonds. 2. The vinyl polymer according to claim 1, wherein the ratio of weight average molecular weight to number average molecular weight as determined by gel permeation chromatography is not more than 1.7. 3. The vinyl polymer according to claim 1, wherein the ratio of weight average molecular weight to number average molecular weight as determined by gel permeation chromatography is not more than 1.6. 4. The vinyl polymer according to claim 1, wherein the ratio of weight average molecular weight to number average molecular weight as determined by gel permeation chromatography is not more than 1.5. 5. The polymer according to claim 1, wherein its main chain is a (meth)acrylic polymer. 6. The polymer according to claim 5, wherein the main chain is an acrylate ester polymer. 7. The polymer according to claim 1, wherein the main chain is produced by atom transfer radical polymerization. 8. The polymer according to claim 1 as produced by converting a terminal halogen group of the halogen-terminated vinyl polymer to an alkenyl-containing substituent. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
FIELD OF THE INVENTION The present invention relates to a crosslinking silyl-, alkenyl- or hydroxy-terminated vinyl polymer. More particularly, it relates to a vinyl polymer which has a narrow molecular weight distribution, hence is easy to handle. PRIOR ART Intramolecular crosslinking silyl group-containing vinyl polymers, in particular (meth) acrylic polymers, are used in weather-resistant paints utilizing the high weather resistance based on their main chain and crosslinking points. These (meth)acrylic polymers are generally produced by copolymerizing a crosslinking silyl-containing (meth)acrylic monomer with one or more other monomers and therefore have crosslinking silyl groups at random positions in the molecular chain, hence they are difficult to use as rubber-like materials. On the other hand, attempts have been made to produce (meth)acrylic polymers having crosslinking silyl groups at molecular ends for use as sealants or adhesives. For producing (meth)acrylic polymers having terminal crosslinking silyl groups, Japanese Kokoku Publication Hei-03-14068, for instance, discloses a method comprising polymerizing a (meth)acrylic monomer in the presence of a crosslinking silyl-containing mercaptan, a crosslinking silyl-containing disulfide and a crosslinking silyl-containing radical polymerization initiator; Japanese Kokoku Publication Hei-04-55444 discloses a method comprising polymerizing a acrylic monomer in the presence of a crosslinking silyl-containing hydrosilane compound or a tetrahalosilane; and Japanese Kokai Publication Hei-06-211922 describes a method for producing crosslinking silyl-terminated (meth)acrylic polymers which comprises first synthesizing a hydroxy-terminated acrylic polymer by using a hydroxyl-containing polysulfide in a larger amount as compared with the initiator and then converting the hydroxyl groups. Meanwhile, it is known that alkenyl-terminated polymers, when crosslinked by themselves or using a curing agent such as a hydrosilyl-containing compound, give cured products excellent in heat resistance and durability. The main chain skeletons of such polymers include 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; polyester polymers such as polyethylene terephthalate, polybutylene terephthalate and polycaprolactone; and polysiloxane polymers such as polydimethylsiloxane, among others. They are used in various applications according to the characteristics of the respective main chain skeletons. As compared with those polymers mentioned above which are obtained by ionic polymerization or condensation polymerization, alkenyl-terminated vinyl polymers obtainable by radical polymerization have scarcely been put to practical use. Among vinyl polymers, meth(acrylic) polymers have high weather resistance, transparency and other characteristics which the above-mentioned polyether polymers or polyester polymers cannot have. For example, vinyl polymers having alkenyl groups in side chains are used in paint compositions for obtaining high weather resistance. If alkenyl-terminated vinyl polymers could be obtained in a simple manner, cured products superior in physical characteristics to cured products from vinyl polymers having alkenyl groups in side chains could be obtained. Therefore, a large number of researchers have made investigations in an attempt to establish a method of producing the same. It is not easy, however, to produce them on a commercial scale. Japanese Kokai Publication Hei-01-247403 discloses a method for synthesizing vinyl polymers having alkenyl groups on both ends which uses an alkenyl-containing disulfide as a chain transfer agent, and Japanese Kokai Publication Hei-06-211922 discloses a method for synthesizing vinyl polymers having alkenyl groups on both ends which comprises synthesizing a vinyl polymer having hydroxyl groups on both ends using a hydroxyl-containing disulfide and then utilizing the reactivity of the hydroxyl groups. By these methods, however, it is difficult to introduce alkenyl groups at both ends without fail and it is impossible to obtain cured products having satisfactory characteristics. For introducing alkenyl groups at both ends with certainty, it is necessary to use the chain transfer agent in large amounts, and this offers a problem from the production process viewpoint. Since, in these methods, ordinary radical polymerization techniques are used, it is difficult to control the molecular weight and molecular weight distribution (ratio of weight average molecular weight to number average molecular weight). It is also known that hydroxyl-terminated polymers, when crosslinked using a compound having functional groups capable of reacting with a hydroxyl group, for example an isocyanate compound, as a curing agent, give cured products excellent in heat resistance and durability, among others. As the main chain skeletons of such hydroxyl-terminated polymers, there may be mentioned, as in the case of alkenyl-terminated polymers, polyether polymers such as polyethylene oxide, polypropylene oxide and polytetramethylene oxide; hydrocarbon polymers such as polybutadiene, polyisoprene, polychloroprene and polyisobutylene and hydrogenation products derived from these; and polyester polymers such as polyethylene terephthalate, polybutylene terephthalate and polycaprolactone, among others. Said polymers are used in various applications according to the main chain skeleton and mode of crosslinking thereof. Vinyl polymers, in particular (meth)acrylic polymers, have such characteristics that the above-mentioned polyether polymers, hydrocarbon polymers or polyester polymers cannot have, for example high weather resistance and transparency, and those having hydroxyl groups in side chains are utilized in weather-resistant paint compositions, for instance. If hydroxyl-terminated vinyl polymers could be obtained in a simple manner, cured products superior in physical characteristics to cured products from vinyl polymers having hydroxyl groups in side chains could be obtained. Therefore, a large number of researchers have made investigations in an attempt to establish a method of producing the same. It is not easy, however, to produce them on a commercial scale. Japanese Kokai Publication Hei-05-262808 discloses a method for synthesizing (meth)acrylic polymers having hydroxyl groups at both ends which comprises using a hydroxyl-containing disulfide as a chain transfer agent. For introducing hydroxyl groups at both ends with certainty, it is necessary to use the chain transfer agent in large amounts as compared with the initiator, and this offers a problem from the production process viewpoint. Japanese Kokoku Publication Hei-01-19402 discloses a method for producing (meth)acrylic polymers having hydroxyl groups at both ends which comprises using hydrogen peroxide as an initiator. It is difficult, however, to introduce, by this method, hydroxyl groups at both ends with certainty. In fact, the method actually employed there comprises copolymerizing a hydroxyl-containing vinyl monomer (e.g. 2-hydroxyethyl methacrylate). Further, Japanese Kokai Publication Hei-04-132706 discloses a method for hydroxyl-terminated vinyl polymers which comprises producing a halogen-terminated (meth)acrylic polymer by polymerizing a (meth)acrylic monomer or monomers using a telogen such as methylene dibromide and reacting the terminal halogen atoms with a nucleophilic agent such as a diol compound, a hydroxyl-containing carboxylic acid, a hydroxyl-containing amine or the like for substitution. By this method, however, it is still difficult to achieve high-rate hydroxyl group introduction at both ends, since the chain transfer of the telogen is not sufficient. In addition, since the methods mentioned above all use ordinary radical polymerization techniques, the polymers obtained have a broad molecular weight distribution (ratio of weight average molecular weight to number average molecular weight) (generally not less than 2) and therefore produce a high viscosity problem. The problem is that when the polymers are used in sealant or adhesive compositions, a high viscosity makes it difficult to handle the compositions on the occasion of application or makes it impossible to incorporate a large amount of fillers for reinforcement. Accordingly, it is a primary object of the present invention to solve the above problems and provide vinyl polymers which have a narrow molecular weight distribution and therefore are easy to handle. Recently, intensive studies have been made on living radical polymerization (see, for example, Matyjaszewski et al., J. Am. Chem. Soc., 1995, 117, 5614, Macromolecules, 1995, 28, 7901, Science, 1996, 272, 866; International Publication Patent W096/30421 and W097/18247; Sawamoto et al., Macromolecules, 1995, 28, 1721) and it is now possible to obtain halogen-terminated vinyl polymers showing a narrow molecular weight distribution by utilizing this polymerization technique. The present inventors found that crosslinking silyl-, alkenyl- or hydroxyl-terminated vinyl polymers showing a narrow molecular weight distribution can be obtained by using this new living radical polymerization technique. Based on such findings, the present inventors have now completed the present invention. SUMMARY OF THE INVENTION The present invention consists in a vinyl polymer which has at least one terminal functional group per molecule and has a ratio of weight average molecular weight to number average molecular weight of less than 1.8 as determined by gel permeation chromatography, said terminal functional group being a crosslinking silyl group of the general formula (1) shown below, an alkenyl group of the general formula (2) shown below or a hydroxyl group: --[Si(R.sup.1).sub.2-b (Y).sub.b O].sub.m --Si(R.sup.2).sub.3-a (Y).sub.a (1) wherein R.sup.1 and R.sup.2 each independently represents 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 of the formula (R.sup.1).sub.3 SiO-- (R' being a monovalent hydrocarbon residue containing 1 to 20 carbon atoms and the three R' groups being the same or different), provided that when a plurality of R.sup.1 or R.sup.2 groups occur, they may be the same or different; Y represents a hydroxyl group or a hydrolyzable group, provided that when a plurality of Y groups occur, they may be the same or different; a represents 0, 1, 2 or 3, b represents 0, 1 or 2, and m represents an integer of 0 to 19, provided that the condition a +mb.gtoreq.1 should be satisfied; H.sub.2 C.dbd.C(R.sup.3)-- (2) wherein R.sup.3 represents a hydrogen atom or a methyl group. BRIEF DESCRIPTION OF THE INVENTION The present invention consists in a vinyl polymer which has at least one terminal functional group per molecule and has a ratio of weight average molecular weight to number average molecular weight of less 1.8 as determined by gel permeation chromatography, said terminal functional group being a crosslinking silyl group of the general formula (1) shown below, an alkenyl group of the general formula (2) shown below or a hydroxyl group: --[Si(R.sup.1).sub.2-b (Y).sub.b O].sub.m Si(R.sup.2).sub.3-a (Y).sub.a (1) wherein R.sup.1 and R.sup.2 each independently represents 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 of the formula (R').sub.3 SiO-- (R' being a monovalent hydrocarbon residue containing 1 to 20 carbon atoms and the three R' groups being the same or different), provided that when a plurality of R.sup.1 or R.sup.2 groups occur, they may be the same or different; Y represents a hydroxyl group or a hydrolyzable group, provided that when a plurality of Y groups occur, they may be the same or different; a represents 0, 1, 2 or 3, b represents 0, 1 or 2, and m represents an integer of 0 to 19, provided that the condition a+mb 1 should be satisfied; H.sub.2 C.dbd.C(R.sup.3)-- (2) wherein R.sup.3 represents a hydrogen atom or a methyl group. The number of the crosslinking silyl groups of general formula (1), the alkenyl groups of general formula (2) or the hydroxyl groups is at least one, preferably 1.2 to 4, per molecule. If said number is smaller than 1, the curable compositions containing said vinyl polymer may have poor curability. The vinyl polymer of the present invention is characterized in that the molecular weight distribution thereof, namely the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn), Mw/Mn, as determined by gel permeation chromatography (GPC) is narrow. The molecular weight distribution value is less than 1.8, preferably not more than 1.7, more preferably not more than 1.6, most preferably not more than 1.5, in particular not more than 1.4, and most desirably not more than 1.3. In the practice of the present invention, the GPC measurement is not limited to any particular technique but, generally, it is performed on a polystyrene gel column using chloroform as a mobile phase. The number average molecular weight, for instance, can be determined as a polystyrene equivalent. The number average molecular weight of the vinyl polymer of the present invention is not critical but is preferably within the range of 500 to 100,000, more preferably within the range of 3,000 to 50,000. When said molecular weight is less than 500, the characteristics intrinsic to a vinyl polymer cannot be expressed whereas a molecular weight exceeding 100,000 makes handling difficult. The vinyl monomer usable in the production of the main chain of the vinyl polymer of the present invention is not limited to any particular species but includes various monomers, for example (meth)acrylic acid monomers such as (meth)acrylic acid, methyl(meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, phenyl (meth)acrylate, toluyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, stearyl (meth)acrylate, glycidyl (meth)acrylate, 2-aminoethyl (meth)acrylate, -(methacryloyloxypropyl)trimethoxysilane, (meth)acrylic acid-ethylene oxide adducts, trifluoromethylmethyl (meth)acrylate, 2-trifluoromethylethyl (meth)acrylate, 2-perfluoroethylethyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate, 2-perfluoroethyl (meth)acrylate, perfluoromethyl (meth)acrylate, diperfluoromethylmethyl (meth)acrylate, 2-perfluoromethyl-2-perfluoroethylethyl (meth)acrylate, 2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl (meth)acrylate and 2-perfluorohexadecylethyl (meth)acrylate; styrenic monomers such as styrene, vinyltoluene, .alpha.-methylstyrene, chlorostyrene, styrenesulfonic acid and salts thereof; fluorine-containing vinyl monomers such as perfluoroethylene, perfluoropropylene and vinylidene fluoride; silicon-containing vinyl monomers such as vinyltrimethoxysilane and vinyltriethoxysilane; maleic anhydride, maleic acid, maleic acid monoalkyl esters and dialkyl esters; fumaric acid, fumaric acid monoalkyl esters and dialkyl esters; maleimide monomers such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide and cyclohexylmaleimide; nitrile-containing vinyl monomers such as acrylonitrile and methacrylonitrile; amido-containing vinyl monomers such as acrylamide and methacrylamide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate and vinyl cinnamate; alkenes such as ethylene and propylene; conjugated dienes such as butadiene and isoprene; vinyl chloride, vinylidene chloride, allyl chloride, allyl alcohol, etc. These may be used alone or a plurality thereof may be copolymerized. From the viewpoint of physical properties of products, styrenic monomers and (meth)acrylic monomers are preferred. More preferred are acrylic acid ester monomers and methacrylic acid ester monomers, and particularly preferred is butyl acrylate. In the practice of the present invention, these preferred monomers may be copolymerized with another or other monomers and, on that occasion, said preferred monomers preferably account for at least 40% by weight. The term "(meth)acrylic acid" or the like as used herein means acrylic acid and/or methacrylic acid. The hydrolyzable group represented by Y in formula (1) in the crosslinking silyl-terminated polymer is not limited to any particular species but includes those already known in the art, for example hydrogen, halogen, alkoxy, acyloxy, ketoxymato, amino, amido, aminoxy, mercapto and alkenyloxy. Alkoxy groups are particularly preferred since they have mild hydrolyzability and therefore are easy to handle. Each silicon atom may have one to three such hydrolyzable groups or hydroxyl groups and the sum a+mb, namely the sum total of hydrolyzable groups is preferably within the range of 1 to 5. When the crosslinking silyl group contains two or more hydrolyzable groups and hydroxyl groups, these groups may be the same or different. The crosslinking silyl group may comprise one or more silicon atoms as constituents thereof and, when silicon atoms are linked via siloxane bonding, the number of such silicon atoms may be up to about 20. The alkenyl group of general formula (2) in the alkenyl-terminated polymer is now described in further detail. First, there may be mentioned alkenyl groups of the general formula (3), which are bound to the main chain via a hydrocarbon group: H.sub.2 C.dbd.C(R.sup.4)--R.sup.5 -- (3) wherein R.sup.4 is as defined above and R.sup.5 represents a direct bond, an alkylene group containing 1 to 20 carbon atoms, an arylene group containing 6 to 20 carbon atoms or an aralkylene group containing 7 to 20 carbon atoms and may containing one or more ether bonds. Specific examples of R.sup.5 other than a direct bond include, but are not limited to, --(CH.sub.2).sub.n -- (n being an integer of 1 to 20), --CH(CH.sub.3)CH.sub.2 --, --CH(CH.sub.3)(CH.sub.2).sub.2 --, --CH.sub.2 CH(CH.sub.3)--, --C(CH.sub.3).sub.2 --, --(CH.sub.2).sub.n --O--(CH.sub.2).sub.m -- (n and m each independently being an integer of 1 to 20 on condition that n+m.ltoreq.20), o--, m--, p--C.sub.6 H.sub.4, o--, m--, p--(CH.sub.2).sub.n --C.sub.6 H.sub.4 --(CH.sub.2).sub.m -- (n and m each independently being an integer of 0 to 14 on condition that n+m.ltoreq.14), and the like. The alkenyl group of general formula (2) further includes alkenyl groups of the general formula (4) which are bound to the main chain via an ether bond, alkenyl groups of the general formula (5) or (6) which are bound to the main chain via an ester bond and, further, alkenyl groups of the general formula (7) which are bound to the main chain via a carbonate group: H.sub.2 C.dbd.C(R.sup.4)--R.sup.5 --O-- (4) H.sub.2 C.dbd.C(R.sup.4)--R.sup.5 --OC(O)-- (5) H.sub.2 C.dbd.C(R.sup.4)--R.sup.5 --C(O)O-- (6) H.sub.2 C.dbd.C(R.sup.4)--R.sup.5 --OC(O)O-- (7) wherein R.sup.4 and R.sup.5 are as defined above. As specific examples of R.sup.5, those specifically mentioned hereinabove all can suitably be used. Now, more detailed mention is made of the hydroxyl group contained in the hydroxy-terminated polymer of the invention. First, there may be mentioned a hydroxyl group bound to the main chain via a hydrocarbon group, as represented by the general formula (8): HO--R.sup.6 -- (8) wherein R.sup.6 represents a direct bond, an alkylene group containing 1 to 20 carbon atoms, an arylene group containing 6 to 20 carbon atoms or an aralkylene group containing 7 to 20 carbon atoms and may contain one or more ether bonds. Specific examples of R.sup.6 other than a direct bond include, but are not limited to, --(CH.sub.2).sub.n -- (n being an integer of 1 to 20), --CH(CH.sub.3)CH.sub.2 --, --CH(CH.sub.3)(CH.sub.2).sub.2 --, --CH.sub.2 CH(CH.sub.3)--, --C(CH.sub.3).sub.2 --, --(CH.sub.2).sub.n --O--(CH.sub.2).sub.m -- (n and m each independently being an integer of 1 to 20 on condition that n+m.ltoreq.20), --CH(C.sub.6 H.sub.5)--, --C(CH.sub.3)(C.sub.6 H.sub.5)--, o--, m--, p--C.sub.6 H.sub.4, o--, m--, p--(CH.sub.2).sub.n --C.sub.6 H.sub.4 --(CH.sub.2).sub.m -- (n and m each independently being an integer of 0 to 14 on condition that n+m.ltoreq.14), and the like. As other examples of the terminal hydroxyl group, there may be mentioned a hydroxyl group bound to the main chain via an ether bond, as represented by the general formula (9), a hydroxyl group bound to the main chain via an ester bond, as represented by the general formula (10) or (11) and, further, a hydroxyl group bound to the main chain via a carbonate bond, as represented by the general formula (12): HO--R.sup.7 --O-- (9) HO--R.sup.7 --OC(O)-- (10) HO--R.sup.7 --C(O)O-- (11) HO--R.sup.7 --OC(O)O-- (12) wherein R.sup.7 represents an alkylene group containing 1 to 20 carbon atoms, an arylene group containing 6 to 20 carbon atoms or an aralkylene group containing 7 to 20 carbon atoms and may contain one or more ether bonds. As preferred specific examples of R.sup.7, there may be mentioned those mentioned above as specific examples of R.sup.6 (exclusive of a direct bond). Polymer Main Chain Synthesis The main chain of the vinyl polymer of the present invention is preferably, but is not limited to, one produced by living radical polymerization. Living radical polymerization is the radical polymerization in which the polymer terminus retains its activity without losing it. In a narrow sense of the term, living polymerization means the polymerization in which the terminus always retain its activity but, generally, the term also include the pseudo-living polymerization in which the inactivated termini and activated termini are in an equilibrium state. The latter definition is applied in the present invention. In recent years, various groups have been engaged in extensive studies of living radical polymerization. As examples, there may be mentioned the use of a cobalt-porphyrin complex (J. Am. Chem. Soc., 1994, 116, 7943), the use of a radical scavenger such as a nitroxide compound (Macromolecules, 1994, 27, 7228), and atom transfer radical polymerization using an organohalogen compounds or the like as an initiator and a transition metal complex as a catalyst. In the practice of the present invention, there is no particular limitation as to which of these techniques should be employed. In view of the ease of control, among others, the technique of atom transfer radical polymerization is preferred. The atom transfer radical polymerization is carried out using an organohalogen compound, a halogenated sulfonyl compound or the like as an initiator and a metal complex containing a transition metal as the central atom as a catalyst. (See, for example, Matyjaszewski et al., J. Am. Chem. Soc., 1995, 117, 5614, Macromolecules, 1995,. 28, 7901, Science, 1996, 272, 866; International Publication Patent WO96/30421 and WO97/18247; Sawamoto et al., Macromolecules, 1995, 28, 1721). When these techniques are employed, despite the fact that the rate of polymerization is generally high and that the reaction involved is radical polymerization which tends to allow termination reactions such as coupling of radicals with each other, the polymerization proceeds in a living manner, giving polymers with a narrow molecular weight distribution (i.e. a Mw/Mn ratio of about 1.1 to 1.5), and the molecular weight can be controlled arbitrarily by selecting the monomer/initiator charge ratio. In carrying out said atom transfer radical polymerization, the use of an organohalogen compound, in particular an organohalogen compound having a highly reactive carbon-halogen bond (e.g. an ester compound having a halogen at the .alpha.-position, or a compound having a halogen at the benzyl position) or a halogenated sulfonyl compound as an initiator is preferred. The transition metal complex to be used as a catalyst in the above living radical polymerization is not limited to any particular species but includes, as preferred species, group 7, 8, 9, 10 or 11 transition metal complexes, more preferably complexes of copper(0), copper(I), ruthenium(II), iron(II) or nickel(II). Among these, copper complexes are preferred. Specific examples of the copper(I) compound are cuprous chloride, cuprous bromide, cuprous iodide, cuprous cyanide, cuprous oxide and cuprous perchlorate. When a copper compound is used, a ligand such as 2,2'-bipyridyl or a derivative thereof, 1,10-phenanthroline or a derivative thereof, tetramethylethylenediamine, pentamethyldiethylenetriamine, hexamethyltris(2-aminoethyl)amine or the like polyamine is added for increasing the catalyst activity. Ruthenium(II) chloride-tristriphenylphosphine complex (RuCl.sub.2 (PPh.sub.3).sub.3) is also suited as a catalyst. In cases where a ruthenium compound is used as a catalyst, an aluminum alkoxide is added as an activator. Further, a bistriphenylphosphine complex of iron(II) (FeCl.sub.2 (PPh.sub.3).sub.2), a bistriphenylphosphine complex of nickel(II) (NiCl.sub.2 (PPh.sub.3).sub.2) and a bistributylphosphine complex of nickel (II) (NiBr.sub.2 (PBu.sub.3).sub.2) are also suited as catalysts. In carrying out this polymerization method, an organohalogen compound or a halogenated sulfonyl compound is generally used as an initiator. Specific examples are C.sub.6 H.sub.5 --CH.sub.2 X, C.sub.6 H.sub.5 --C(H)(X)CH.sub.3, C.sub.6 H.sub.5 --C(X)(CH.sub.3).sub.2 (wherein C.sub.6 H.sub.5 is a phenyl group and X is a chlorine, bromine or iodine atom); R.sup.8 --C(H)(X)--CO.sub.2 R.sup.9, R.sup.8 C(CH.sub.3)(X)--CO.sub.2 R.sup.9, R.sup.8 --C(H)(X)--C(O)R.sup.9, R.sup.8 C(CH.sub.3)(X)--C(O)R (wherein R.sup.8 and R.sup.9 are the same or different and each is a hydrogen atom or an alkyl, aryl or aralkyl group containing up to 20 carbon atoms and X is a chlorine, bromine or iodine atom); and R.sup.8 --C.sub.6 H.sub.4 --SO.sub.2 X (wherein R.sup.8 is a hydrogen atom or an alkyl, aryl or aralkyl group containing up to 20 carbon atoms and X is a chlorine, bromine or iodine atom). For producing polymers having two or more terminal structures of the present invention per molecule, the use of an organohalogen compound or halogenated sulfonyl compound having two or more initiation sites is preferred as an initiator. Specific examples are ##STR1## ##STR2## and the like. The vinyl monomer to be used in this polymerization is not limited to any particular species but includes those already mentioned hereinabove as suitable species. This polymerization can be carried out in the absence of a solvent or in various solvents. As the solvents, there may be mentioned hydrocarbon solvents such as benzene and toluene; ether solvents such as diethyl ether, tetrahydrofuran, diphenyl ether, anisole and dimethoxybenzene; halogenated hydrocarbon solvents such as methylene chloride, chloroform and chlorobenzene; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; alcohol solvents such as methanol, ethanol, propanol, isopropanol, n-butyl alcohol and tert-butyl alcohol; nitrile solvents such as acetonitrile, propionitrile and benzonitrile; ester solvents such as ethyl acetate and butyl acetate; carbonate solvents such as ethylene carbonate and propylene carbonate; and the like. These may be used singly or two or more of them may be used in admixture. The polymerization can also be carried out in an emulsion system or in a system to use the supercritical fluid CO.sub.2 as a medium. This polymerization can be carried out within the temperature range from room temperature to 200, preferably within the range of 50 to 150. Introduction of Terminal Functional Groups The method for introducing crosslinking silyl groups, alkenyl groups or hydroxyl groups into the polymer at the ends thereof is not critical. There can be mentioned the use of an organohalogen compound or halogenated sulfonyl compound having a functional group other than the functional group serving to initiate the polymerization as an initiator for atom transfer radical polymerization, the conversion of the terminal halogen or other functional groups of the polymer, or the combined use of these. When, in the atom transfer radical polymerization, an organohalogen compound or halogenated sulfonyl compound having a function group other than the functional group serving to initiate the polymerization is used, a vinyl polymer having said functional group at one end and the halogen at the other end can be obtained. By converting the halogen at the termination end of the thus-obtained polymer to a desired functional group, it is possible to obtain a vinyl polymer having functional groups at both ends. For realizing such conversion, the methods mentioned later herein can be used. The vinyl polymer having functional groups at both ends can also be obtained by using a compound having a total of two or more functional groups which may be the same or different with each other and which are capable of substituting for the terminal halogen of said polymer to thereby causing coupling of two or more halogen termini together. This compound for coupling is not limited to any particular species but include, as preferred species, polyols, polyamines, polycarboxylic acids, polythiols, salts of these, alkali metal sulfides and the like. Referring to the functional group-containing organohalogen or halogenated sulfonyl compound mentioned above, the functional group includes, among others, alkenyl, crosslinking silyl, hydroxyl, epoxy, amino and amido groups. The alkenyl-containing organohalogen compound includes, but is not limited to, compounds having the structure represented by the general formula (13): R.sup.10 R.sup.11 C(X)--R.sup.12 --R.sup.13 --C(R.sup.3).dbd.CH.sub.2 (13) wherein R.sup.3 is hydrogen or methyl, R.sup.10 and R.sup.11 each is hydrogen or a monovalent alkyl, aryl or aralkyl group containing up to 20 carbon atoms or combinedly represent a divalent group derived from two such groups by mutual ligation at respective other ends, R.sup.12 is --C(O)O-- (ester group), --C(O)-- (keto group) or o-, m- or p-phenylene, R.sup.13 is a direct bond or a divalent organic group containing 1 to 20 carbon atoms which may optionally contain one or more ether bonds, and X is chlorine, bromine or iodine, for instance. As specific examples of the substituents R.sup.10 and R.sup.11 there may be mentioned hydrogen, methyl, ethyl, n-propyl, isopropyl, butyl, pentyl and hexyl. R.sup.10 and R.sup.11 may form a ring skeleton resulting from mutual ligation at respective other ends. As specific examples of the alkenyl-containing organohalogen compound of general formula (13), there may be mentioned XCH.sub.2 C(O)O(CH.sub.2).sub.n CH.dbd.CH.sub.2, H.sub.3 CC(H)(X)C(O)O(CH.sub.2).sub.n CH.dbd.CH.sub.2, (H.sub.3 C).sub.2 C(X)C(O)O(CH.sub.2).sub.n CH.dbd.CH.sub.2, CH.sub.3 CH.sub.2 C(H)(X)C(O)O(CH.sub.2).sub.n CH.dbd.CH.sub.2, ##STR3## (in each of the above formulas, X is chlorine, bromine or iodine and n is an integer of 0 to 20), XCH.sub.2 C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m CH.dbd.CH.sub.2, H.sub.3 CC(H)(X)C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m CH.dbd.CH.sub.2, (H.sub.3 C).sub.2 C(X)C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m CH.dbd.CH.sub.2, CH.sub.3 CH.sub.2 C(H)(X)C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m CH.dbd.CH.sub.2, ##STR4## of the above formulas, X is chlorine, bromine or iodine, n is an integer of 1 to 20, and m is an integer of 0 to 20), o, m, p--XCH.sub.2 --C.sub.6 H.sub.4 --(CH.sub.2).sub.n --CH.dbd.CH.sub.2, o, m, p--CH.sub.3 C(H)(X)--C.sub.6 H.sub.4 --(CH.sub.2).sub.n --CH.dbd.CH.sub.2, o, m, p--CH.sub.3 CH.sub.2 C(H)(X)--C.sub.6 H.sub.4 --(CH.sub.2).sub.n --CH.dbd.CH.sub.2, (in each of the above formulas, X is chlorine, bromine or iodine and n is an integer of 0 to 20), o, m, p--XCH.sub.2 --C.sub.6 H.sub.4 --(CH.sub.2).sub.n --O--(CH.sub.2).sub.m CH.dbd.CH.sub.2, o, m, p--CH.sub.3 C(H)(X)--C.sub.6 H.sub.4 --(CH.sub.2).sub.n --O--(CH.sub.2).sub.m --CH.dbd.CH.sub.2, o, m, p--CH.sub.3 CH.sub.2 C(H)(X)--C.sub.6 H.sub.4 --(CH.sub.2).sub.n --O--(CH.sub.2).sub.m CH.dbd.CH.sub.2, (in each of the above formulas, X is chlorine, bromine or iodine, n is an integer of 1 to 20, and m is an integer of 0 to 20), o, m, p--XCH.sub.2 --C.sub.6 H.sub.4 --O--(CH.sub.2).sub.n --CH.dbd.CH.sub.2, o, m, p--CH.sub.3 C(H)(X)--C.sub.6 H.sub.4 --O--(CH.sub.2).sub.n --CH.dbd.CH.sub.2, o, m, p--CH.sub.3 CH.sub.2 C(H)(X)--C.sub.6 H.sub.4 --O--(CH.sub.2).sub.n --CH.dbd.CH.sub.2, (in each of the above formulas, X is chlorine, bromine or iodine and n is an integer of 0 to 20), o, m, p--XCH.sub.2 --C.sub.6 H.sub.4 --O--(CH.sub.2).sub.n --O--(CH.sub.2).sub.m --CH.dbd.CH.sub.2, o, m, p--CH.sub.3 C(H)(X)--C.sub.6 H.sub.4 --O--(CH.sub.2).sub.n --O--(CH.sub.2).sub.m --CH.dbd.CH.sub.2, o, m, p--CH.sub.3 CH.sub.2 C(H)(X)--C.sub.6 H.sub.4 --O--(CH.sub.2).sub.n --O--(CH.sub.2).sub.m --CH.dbd.CH.sub.2, (in each of the above formulas, X is chlorine, bromine or iodine, n is an integer of 1 to 20, and m is an integer of 0 to 20). As further examples of the alkenyl-containing organohalogen compound, there may be mentioned compounds of general formula (14): H.sub.2 C.dbd.C(R.sup.3)--R.sup.13 --C(R.sup.10)(X)--R.sup.14 --R.sup.11 (14) wherein R.sup.3, R.sup.10, R.sup.11, R.sup.13 and X are as defined above and R.sup.14 represents a direct bond, --C(O)O-- (ester bond), --C(O)-- (keto bond) or o-, m- or p-phenylene. R.sup.13 is a direct bond or an divalent organic group containing 1 to 20 carbon atoms (which may contain one or more ether bonds). When it is a direct bond, the vinyl group is bound to the halogen-carrying carbon atom, forming a halogenated allyl compound. In that case, the carbon-halogen bond is activated by the adjacent vinyl group and therefore the C(O)O or phenylene group as R.sup.14 is not always necessary but a direct bond may suffice. In cases where R.sup.13 is other than a direct bond, the occurrence of a C(O)O, C(O) or phenylene group as R.sup.14 is preferred for the activation of the carbon-halogen bond. Specific examples of the compound of general formula (14) are: CH.sub.2.dbd.CHCH.sub.2 X, CH.sub.2.dbd.C(CH.sub.3)CH.sub.2 X, CH.sub.2.dbd.CHC(H)(X)CH.sub.3, CH.sub.2.dbd.C(CH.sub.3)C(H)(X)CH.sub.3, CH.sub.2.dbd.CHC(X)(CH.sub.3).sub.2, CH.sub.2.dbd.CHC(H)(X)C.sub.2 H.sub.5, CH.sub.2.dbd.CHC(H)(X)CH(CH.sub.3).sub.2, CH.sub.2.dbd.CHC(H)(X)C.sub.6 H.sub.5, CH.sub.2.dbd.CHC(H)(X)CH.sub.2 C.sub.6 H.sub.5, CH.sub.2.dbd.CHCH.sub.2 C(H)(X)--CO.sub.2 R, CH.sub.2.dbd.CH(CH.sub.2).sub.2 C(H)(X)--CO.sub.2 R, CH.sub.2.dbd.CH(CH.sub.2).sub.3 C(H)(X)--CO.sub.2 R, CH.sub.2.dbd.CH(CH.sub.2).sub.8 C(H)(X)--CO.sub.2 R, CH.sub.2.dbd.CHCH.sub.2 C(H)(X)--C.sub.6 H.sub.5, CH.sub.2.dbd.CH(CH.sub.2).sub.2 C(H)(X)--C.sub.6 H.sub.5, and CH.sub.2.dbd.CH(CH.sub.2).sub.3 C(H)(X)--C.sub.6 H.sub.5, (in each of the above formulas, X is chlorine, bromine or iodine, and R is an alkyl, aryl or aralkyl group containing up to 20 carbon atoms). Specific examples of the alkenyl-containing halogenated sulfonyl compound are: o--, m--, p--CH.sub.2.dbd.CH--(CH.sub.2).sub.n --C.sub.6 H.sub.4 --SO.sub.2 X, o--, m--, p--CH.sub.2.dbd.CH--(CH.sub.2).sub.n --O--C.sub.6 H.sub.4 --SO.sub.2 X, (in each of the above formulas, X is chlorine, bromine or iodine, and n is an integer of 0 to 20), and the like. The crosslinking silyl-containing organohalogen compound is not limited to any particular species but includes, among others, compounds having the structure of the general formula (15): R.sup.10 R.sup.11 C(X)--R.sup.12 --R.sup.13 --C(H)(R.sup.3)CH.sub.2 --[Si(R.sup.15).sub.2-b (Y).sub.b O].sub.m --Si(R.sup.16).sub.3-a (Y).sub.a (15) wherein R.sup.3, R.sup.10, R.sup.11, R.sup.12, R.sup.13 and X are as defined above, R.sup.15 and R.sup.16 each represents an alkyl, aryl or aralkyl group containing up to 20 carbon atoms or a triorganosiloxy group of the formula (R').sub.3 SiO-- (in which R' is a monovalent hydrocarbon group containing 1 to 20 carbon atoms and the three R' groups may be the same or different) and when two or more R.sup.9 or R.sup.10 groups coccur, they may be the same or different; Y represents a hydroxyl group or a hydrolyzable group and when two ore more Y groups occur, they may be the same or different; a represents 0, 1, 2 or 3, b represents 0, 1 or 2, and m represents an integer of 0 to 19, provided that the condition a+mb 1 should be satisfied. Specific examples of the compound of general formula (15) are: XCH.sub.2 C(O)O(CH.sub.2).sub.n Si(OCH.sub.3).sub.3, CH.sub.3 C(H)(X)C(O)O(CH.sub.2).sub.n Si(OCH.sub.3).sub.3, (CH.sub.3).sub.2 C(X)C(O)O(CH.sub.2).sub.n Si(OCH.sub.3).sub.3, XCH.sub.2 C(O)O(CH.sub.2).sub.n Si(CH.sub.3)(OCH.sub.3).sub.2, CH.sub.3 C(H)(X)C(O)O(CH.sub.2).sub.n Si(CH.sub.3)(OCH.sub.3).sub.2, (CH.sub.3).sub.2 C(X)C(O)O(CH.sub.2).sub.n Si(CH.sub.3)(OCH.sub.3).sub.2, (in each of the above formula, X is chlorine, bromine or iodine, and n is an integer of 0 to 20), XCH.sub.2 C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m Si(OCH.sub.3).sub.3, H.sub.3 CC(H)(X)C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m Si(OCH.sub.3).sub.3, (H.sub.3 C).sub.2 C(X)C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m Si(OCH.sub.3).sub.3, CH.sub.3 CH.sub.2 C(H)(X)C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m Si(OCH.sub.3).sub.3, XCH.sub.2 C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m Si(CH.sub.3)(OCH.sub.3).sub.2, H.sub.3 CC(H)(X)C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m --Si(CH.sub.3)(OCH.sub.3).sub.2, (H.sub.3 C).sub.2 C(X)C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m --Si(CH.sub.3)(OCH.sub.3).sub.2, CH.sub.3 CH.sub.2 C(H)(X)C(O)O(CH.sub.2).sub.n O(CH.sub.2).sub.m --Si(CH.sub.3)(OCH.sub.3).sub.2, (in each of the above formula, X is chlorine, bromine or iodine, n is an integer of 1 to 20, and m is an integer of 0 to 20), o, m, p--XCH.sub.2 --C.sub.6 H.sub.4 --(CH.sub.2).sub.2 Si(OCH.sub.3).sub.3, o, m, p--CH.sub.3 C(H)(X)--C.sub.6 H.sub.4 --(CH.sub.2).sub.2 Si(OCH.sub.3).sub.3, o, m, p--CH.sub.3 CH.sub.2 C(H)(X)--C.sub.6 H.sub.4 --(CH.sub.2).sub.2 Si(OCH.sub.3).sub.3, o, m, p--XCH.sub.2 --C.sub.6 H.sub.4 --(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, o, m, p--CH.sub.3 C(H)(X)--C.sub.6 H.sub.4 --(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, o, m, p--CH.sub.3 CH.sub.2 C(H)(X)--C.sub.6 H.sub.4 --(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, o, m, p--XCH.sub.2 --C.sub.6 H.sub.4 --(CH.sub.2).sub.2 --O--(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, o, m, p--CH.sub.3 C(H)(X)--C.sub.6 H.sub.4 --(CH.sub.2).sub.2 --O--(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, o, m, p--CH.sub.3 CH.sub.2 C(H)(X)--C.sub.6 H.sub.4 --(CH.sub.2).sub.2 --O--(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, o, m, p--XCH.sub.2 --C.sub.6 H.sub.4 --O--(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, o, m, p--CH.sub.3 C(H)(X)--C.sub.6 H.sub.4 --O--(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, o, m, p--CH.sub.3 CH.sub.2 C(H)(X)--C.sub.6 H.sub.4 --O--(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, o, m, p--XCH.sub.2 --C.sub.6 H.sub.4 --O--(CH.sub.2).sub.2 --O--(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, o, m, p--CH.sub.3 C(H)(X)--C.sub.6 H.sub.4 --O--(CH.sub.2).sub.2 --O--(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, o, m, p--CH.sub.3 CH.sub.2 C(H)(X)--C.sub.6 H.sub.4 --O--(CH.sub.2).sub.2 --O--(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, (in each of the above formulas, X is chlorine, bromine or iodine), and the like. As further examples of the crosslinking silyl-containing organohalogen compound mentioned above, there may be mentioned compounds of the general formula (16): (R.sup.16).sub.3-a (Y).sub.a Si--[OSi(R.sup.15).sub.2-b (Y).sub.b ].sub.m CH.sub.2 --C(H)(R.sup.3)--R.sup.13 --C(R.sup.10)(X)--R.sup.14 --R.sup.11 (16) wherein R.sup.3, R.sup.10, R.sup.11, R.sup.13, R.sup.14, R.sup.16, R.sup.16, a, b, m, X and Y are as defined above. Specific examples of such compounds are: (CH.sub.3 O).sub.3 SiCH.sub.2 CH.sub.2 C(H)(X)C.sub.6 H.sub.5, (CH.sub.3 O).sub.2 (CH.sub.3)SiCH.sub.2 CH.sub.2 C(H)(X)C.sub.6 H.sub.5, (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.2 C(H)(X)--CO.sub.2 R, (CH.sub.3 O).sub.2 (CH.sub.3)Si(CH.sub.2).sub.2 C(H)(X)--CO.sub.2 R, (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.3 C(H)(X)--CO.sub.2 R, (CH.sub.3 O).sub.2 (CH.sub.2)Si(CH.sub.2).sub.3 C(H)(X)--CO.sub.2 R, (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.4 C(H)(X)--CO.sub.2 R, (CH.sub.3 O).sub.2 (CH.sub.3)Si(CH.sub.2).sub.4 C(H)(X)--CO.sub.2 R, (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.9 C(H)(X)--Co.sub.2 R, (CH.sub.3 O).sub.2 (CH.sub.3)Si(CH.sub.2).sub.9 C(H)(X)--CO.sub.2 R, (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.3 C(H)(X)--C.sub.6 H.sub.5, (CH.sub.3 O).sub.2 (CH.sub.3)Si(CH.sub.2).sub.3 C(H)(X)--C.sub.6 H.sub.5, (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.4 C(H)(X)--C.sub.6 H.sub.5, (CH.sub.3 O).sub.2 (CH.sub.3)Si(CH.sub.2).sub.4 C(H)(X)--C.sub.6 H.sub.5, (in each of the above formulas, X is chlorine, bromine or iodine, and R is an alkyl, aryl or aralkyl group containing up to 20 carbon atoms), and the like. The hydroxyl-containing organohalogen or halogenated sulfonyl compound mentioned above is not limited to any particular species but includes compounds of the following formula, for instance: HO--(CH.sub.2).sub.n --OC(O)C(H)(R)(X) wherein X is chlorine, bromine or iodine, R is a hydrogen atom or an alkyl, aryl or aralkyl group containing up to 20 carbon atoms, and n is an integer of 1 to 20. The amino-containing organohalogen or halogenated sulfonyl compound mentioned above is not limited to any particular species but includes compounds of the following formula, for instance: H.sub.2 N--(CH.sub.2).sub.n --OC(O)C(H)(R)(X) wherein X is chlorine, bromine or iodine, R is a hydrogen atom or an alkyl, aryl or aralkyl group containing up to 20 carbon atoms, and n is an integer of 1 to 20. The epoxy-containing organohalogen or halogenated sulfonyl compound mentioned above is not limited to any particular species but includes compounds of the following formulas for instance: ##STR5## wherein X is chlorine, bromine or iodine, R is a hydrogen atom or an alkyl, aryl or aralkyl group containing up to 20 carbon atoms, and n is an integer of 1 to 20. In the following, mention is made of the methods of introducing crosslinking silyl, alkenyl or hydroxyl groups by terminal functional group conversion. Since these functional groups serve as precursors of each other, the description is made in the order going upstream from the crosslinking silyl groups. As the method of synthesizing the vinyl polymer having at least one crosslinking silyl group, there may be mentioned (A) the method comprising adding a hydrosilane compound having a crosslinking silyl group to a vinyl polymer having at least one alkenyl group in the presence of a hydrosilylation catalyst, (B) the method comprising reacting a vinyl polymer having at least one hydroxyl group with a compound having both a crosslinking silyl group and a group capable of reacting with a hydroxyl group, such as an isocyanato group, (C) the method comprising allowing a compound having both a polymerizable alkenyl group and a crosslinking silyl group to react on the occasion of synthesizing a vinyl polymer by radical polymerization, (D) the method comprising using a chain transfer agent containing a crosslinking silyl group on the occasion of synthesizing a vinyl polymer by radical polymerization, and (E) the method comprising reacting a vinyl polymer having at least one highly reactive carbon-halogen bond with a compound having both a crosslinking silyl group and a stable carbanion, among others. The vinyl polymer having at least one alkenyl group, which is to be used in method (A), can be obtained by various methods. Several methods of synthesis are shown below by way of example. They have no limitative meaning, however. (A-a) The method comprising allowing a compound having both a polymerizable alkenyl group and a poorly polymerizable alkenyl group, as represented by the general formula (17) shown below, to react as a second monomer on the occasion of synthesizing a vinyl polymer by radical polymerization: H.sub.2 C.dbd.C(R.sup.23)--R.sup.24 --R.sup.25 --C(R.sup.26).dbd.CH.sub.2 (17) wherein R.sup.23 represents hydrogen or methyl, R.sup.24 represents --C(O)O-- or o-, m- or p-phenylene, R.sup.25 represents a direct bond or a divalent organic group containing 1 to 20 carbon atoms, which may optionally contain one or more ether bonds, and R.sup.26 represents hydrogen or an alkyl group containing 1 to 10 carbon atoms, an aryl group containing 6 to 10 carbon atoms or an aralkyl group containing 7 to 10 carbon atoms. The time to submit to reaction the compound having both a polymerizable alkenyl group and a poorly polymerizable alkenyl group is not critical but it is preferred that said compound be submitted to reaction as the second monomer especially after living radical polymerization and, when rubber-like properties are expected, at the final stage of polymerization or after completion of the polymerization of the given first monomer. (A-b) The method comprising submitting a compound having at least two poorly polymerizable alkenyl groups, such as 1,5-hexadiene, 1,7-octadiene or 1,9-decadiene, to reaction at the final stage of polymerization or after completion of the polymerization of the given first monomer on the occasion of synthesizing a vinyl polymer by living radical polymerization. (A-c) The method comprising reacting various organometallic compounds having an alkenyl group, such as allyltributyltin or allyltrioctyltin, with a vinyl polymer having at least one highly reactive carbon-halogen bond, for replacing the halogen. (A-d) The method comprising reacting a stabilized carbanion having an alkenyl group, as represented by the general formula (18) given below, with a vinyl polymer having at least one highly reactive carbon-halogen bond, for replacing the halogen: M.sup.+ C.sup.- (R.sup.27)(R.sup.28)--R.sup.29 --C(R.sup.26).dbd.CH.sub.2 (18) wherein R.sup.26 is as defined above, R.sup.27 and R.sup.28 each is an electron-withdrawing group capable of stabilizing the carbanion C.sup.- or one of them is an electron-withdrawing group and the other is hydrogen, an alkyl group containing 1 to 10 carbon atoms or a phenyl group, R.sup.29 represents a direct bond or a divalent organic group containing 1 to 10 carbon atoms, which may optionally contain one or more ether bonds, and M.sup.+ represents an alkali metal ion or a quaternary ammonium ion. Preferred as the electron-withdrawing group R.sup.27 and/or R.sup.28 are those having the structure --CO.sub.2 R, --C(O)R and/or --CN. (A-e) The method comprising reacting an elemental metal, such as zinc, or an organometallic compound with a vinyl polymer having at least one highly reactive carbon-halogen bond to thereby form an enolate anion, and then reacting this with an alkenyl-containing electrophilic compound such as an alkenyl-containing compound having a leaving group such as halogen or acetyl, an alkenyl-containing carbonyl compound, an alkenyl-containing isocyanate compound or an alkenyl-containing acid halide. (A-f) The method comprising reacting an alkenyl-containing oxy anion or carboxylate anion represented by the general formula (19) or (20), for instance, with a vinyl polymer having at least one highly reactive carbon-halogen bond, for replacing the halogen: H.sub.2 C.dbd.C(R.sup.26)--R.sup.30 --O.sup.- M.sup.+ (19) wherein R.sup.26 and M.sup.+ are as defined above and R.sup.30 is a divalent organic group containing 1 to 20 carbon atoms, which may optionally contain one or more ether bonds; H.sub.2 C.dbd.C(R.sup.26)--R.sup.31 --C(O)O.sup.- M.sup.+ (20) wherein R.sup.26 and M.sup.+ are as defined above and R.sup.31 is a direct bond or a divalent organic group containing 1 to 20 carbon atoms, which may optionally contain one or more ether bonds. The method for synthesizing the above-mentioned vinyl polymer having at least one highly reactive carbon-halogen bond includes, but is not limited to, the atom transfer radical polymerization method using an organohalogen compound or halogenated sulfonyl compound such as mentioned above as an initiator and a transition metal complex as a catalyst. The vinyl polymer having at least one alkenyl group can also be prepared from a vinyl polymer having at least one hydroxyl group. The method therefor includes, but is not limited to, those mentioned below. Mention thus may be made of the methods comprising reacting the hydroxyl group of a vinyl polymer having at least one hydroxyl group with (A-g) a base such as sodium methoxide, followed by reaction with an alkenyl-containing halide such as allyl chloride; (A-h) an alkenyl-containing isocyanate such as allyl isocyanate; (A-i) an alkenyl-containing acid halide such as (meth)acryloyl chloride in the presence of a base such as pyridine; or (A-j) an alkenyl-containing carboxylic acid such as acrylic acid in the presence of an acid catalyst. In cases where no halogen is directly involved in the alkenyl group introduction, as in (A-a) or (A-b), it is preferable, in the practice of the present invention, to synthesize the vinyl polymer by the living radical polymerization technique. The method (A-b) is more preferred because of ease of control. In cases where the alkenyl group introduction is realized by replacing the halogen atom of a vinyl polymer having at least one highly reactive carbon-halogen bond, the use is preferred of a vinyl polymer having at least one highly reactive terminal carbon-halogen bond obtained by radical polymerization (atom transfer radical polymerization) of a vinyl monomer using an organohalogen compound having at least one highly reactive carbon-halogen bond or a halogenated sulfonyl compound as an initiator and a transition metal complex as a catalyst. From the ease of control viewpoint, the method (A-f) is more preferred. The crosslinking silyl-containing hydrosilane compound to be used in the method (A) is not limited to any particular species but includes, as typical examples, compounds of the general formula (21): H--[Si(R.sup.21).sub.2-b (Y).sub.b O].sub.m --Si(R.sup.22).sub.3-a (Y).sub.a (21) wherein R.sup.21, R.sup.22, a, b, m and Y are as defined above. Among these hydrosilanes, crosslinking group-containing compounds of the general formula (22) are particularly preferred from the ready availability viewpoint: H--Si(R.sup.22).sub.3-a (Y).sub.a (22) wherein R.sup.22, Y and a are as defined above. In adding the crosslinking silyl-containing hydrosilane compound mentioned above to an alkenyl group, a transition metal catalyst is generally used. As the transition metal catalyst, there may be mentioned, for example, elemental platinum; solid platinum dispersed on a carrier such as alumina, silica or carbon black; chloroplatinic acid; a complex of chloroplatinic acid and an alcohol, aldehyde, ketone or the like; a platinum-olefin complex, and platinum(0)-divinyltetramethyldisiloxane complex. As catalyst other than such platinum catalysts, there may be mentioned RhCl(PPh.sub.3).sub.3, RhCl.sub.3, RuCl.sub.3, IrCl.sub.3, FeCl.sub.3, AlCl.sub.3, PdCl.sub.2 H.sub.2 O, NiCl.sub.2, TiCl.sub.4, etc. The method for producing a vinyl polymer having at least one hydroxyl group for use in the methods (B) and (A-g) to (A-j) includes, but is not limited to, the following. (B-a) The method comprising submitting a compound having both a polymerizable alkenyl group and a hydroxyl group, for example a compound of the general formula (23) shown below, to reaction as a second monomer on the occasion of synthesizing a vinyl polymer by radical polymerization: H.sub.2 C.dbd.C(R.sup.23)--R.sup.24 --R.sup.25 --OH (23) wherein R.sup.23, R.sup.24 and R.sup.25 are as defined above. The time for submitting the compound having both a polymerizable alkenyl group and a hydroxyl group to reaction is not critical. Generally, however, it is preferred, when rubber-like properties are expected, that said compound be submitted to reaction as a second monomer in living radical polymerization at the final stage of polymerization or after completion of polymerization of the given first monomer. (B-b) The method comprising submitting an alkenyl alcohol, such as 10-undecenol, 5-hexenol or allyl alcohol, to reaction on the occasion of synthesizing a vinyl polymer by living radical polymerization at the final stage of polymerization or after completion of polymerization of the given first monomer. (B-c) The method comprising subjecting a vinyl monomer to radical polymerization using a large amount of a hydroxyl-containing chain transfer agent, such as a hydroxyl-containing polysulfide, as disclosed, for example, in Japanese Kokai Publication Hei-05-262808. (B-d) The method comprising subjecting a vinyl monomer to radical polymerization using hydrogen peroxide or a hydroxyl-containing initiator, as disclosed, for example, in Japanese Kokai Publication Hei-06-239912 and Hei-08-283310. (B-e) The method comprising subjecting a vinyl monomer to radical polymerization using an excessive amount of an alcohol, as disclosed, for example, in Japanese Kokai Publication Hei-06-116312. (B-f) The method comprising hydrolyzing the halogen of a vinyl polymer having at least one highly reactive carbon-halogen bond or reacting a hydroxyl-containing compound with said halogen to thereby attain terminal hydroxyl introduction, as disclosed, for example, in Japanese Kokai Publication Hei-04-132706. (B-g) The method comprising reacting a vinyl polymer having at least one highly reactive carbon-halogen bond with a hydroxyl-containing stabilized carbanion such as the one represented by the general formula (24), for replacing the halogen: M.sup.+ C.sup.- (R.sup.27)(R.sup.28)--R.sup.29 --OH (24) wherein R.sup.27, R.sup.28 and R.sup.29 are as defined above. Particularly preferred as the electron-withdrawing groups R.sup.27 and R.sup.28 are those having the structure --CO.sub.2 R, --C(O)R or --CN. (B-h) The method comprising reacting an elemental metal such as zinc or an organometallic compound with a vinyl polymer having at least one highly reactive carbon-halogen bond to give an enolate anion and then reacting the latter with an aldehyde or ketone. (B-i) The method comprising reacting a hydroxyl-containing oxy anion or carboxylate anion represented by the general formula (25) or (26), for instance, with a vinyl polymer having at least one highly reactive carbon-halogen bond, for replacing the halogen: HO--R.sup.30 --O.sup.- M.sup.+ (25) wherein R.sup.30 and M.sup.+ are as defined above; HO--R.sup.31 --C(O)O.sup.- M.sup.+ (26) wherein R.sup.31 and M.sup.+ are as defined above. In cases where no halogen is directly involved in the method of hydroxyl introduction, as in (B-a) to (B-e), it is preferred, in the practice of the present invention, that the vinyl polymer be synthesized by the living radical polymerization technique. The method (B-b) is more preferred because of ease of control. In cases where hydroxyl group introduction is realized by conversion of the halogen of a vinyl polymer having at least one highly reactive carbon-halogen bond, the use is preferred of a vinyl polymer having at least one highly reactive terminal carbon-halogen bond as obtained by radical polymerization (atom transfer radical polymerization) of a vinyl monomer using an organohalogen compound or a halogenated sulfonyl compound as an initiator and a transition metal complex as a catalyst. From the ease of control viewpoint, the method (B-i) is more preferred. As the compound having both a crosslinking silyl group and a group capable of reacting with a hydroxyl group, such as an isocyanato group, which is to be used in the method (B), there may be mentioned, for example, -isocyanatopropyltrimethoxysilane, -isocyanatopropyl-methyldimethoxysilane and -isocyanatopropyltri-ethoxysilane. Any of conventional urethane formation catalysts may be used as necessary. The compound having both a polymerizable alkenyl group and a crosslinking silyl group, which is to be used in the method (C), includes, for example, trimethoxysilylpropyl (meth)acrylate, methyldimethoxysilylpropyl (meth)acrylate and like compounds represented by the general formula (27): H.sub.2 C.dbd.C(R.sup.23)--R.sup.32 --R.sup.32 --[Si(R.sup.21).sub.2-b (Y).sub.b O].sub.m --Si(R.sup.22).sub.3-a (Y).sub.a (27) wherein R.sup.21, R.sup.22, R.sup.23, R.sup.24, Y, a, b and m are as defined above, and R.sup.32 represents a direct bond or a divalent organic group containing 1 to 20 carbon atoms, which may optionally contain one or more ether bonds. The time to submit the compound having both a polymerizable alkenyl group and a crosslinking silyl to reaction is not critical. When rubber-like properties are desired, it is preferred that said compound be submitted to reaction as a second monomer in living radical polymerization at the final stage of polymerization or after completion of the polymerization of the given first monomer. The crosslinking silyl-containing chain transfer agent to be used in the chain transfer agent technique (D) includes, for example, crosslinking silyl-containing mercaptans, crosslinking silyl-containing hydrosilanes and the like, as disclosed in Japanese Kokoku Publication Hei-03-14068 and Hei-04-55444. The method for synthesizing the vinyl polymer having at least one highly reactive carbon-halogen bond, which is to be used in the method (E), is not limited but includes the atom transfer radical polymerization method using an organohalogen compound or halogenated sulfonyl compound such as mentioned above as an initiator and a transition metal complex as a catalyst. As the compound having both a crosslinking silyl group and a stabilized carbanion, which is to be used in the method (E), there may be mentioned compounds of the general formula (28): M.sup.+ C.sup.- (R.sup.27)(R.sup.28)--R.sup.33 --C(H)(R.sup.34)--CH.sub.2 --[Si (R.sup.21).sub.2-b (Y).sub.b O].sub.m --Si(R.sup.22).sub.3-a (Y).sub.a (28) wherein R.sup.21, R.sup.22, R.sup.27, R.sup.28, Y, a, b and m are as defined above, R.sup.33 represents a direct bond or a divalent organic group containing 1 to 10 carbon atoms, which may optionally contain one or more ether bonds, and R.sup.34 represents hydrogen or an alkyl group containing 1 to 10 carbon atoms, an aryl group containing 6 to 10 carbon atoms or an aralkyl group containing 7 to 10 carbon atoms. The electron-withdrawing groups R.sup.27 and R.sup.28 most preferably have the structure --CO.sub.2 R, --C(O)R or --CN. The polymer synthesized in the above manner is a vinyl polymer having a very narrow molecular weight distribution. Therefore, its viscosity is lower as compared with those polymers equivalent in number average molecular weight but broader in molecular weight distribution, hence it is easy to handle in using it in curable compositions. Applications Typical applications of the polymer of the present invention are described in the following according to the terminal functional group species thereof. However, the applications of the polymer of the invention are not limited thereto. The terminal crosslinking silyl-containing vinyl polymer of the present invention can be crosslinked and cured by forming siloxane bonds in the presence or absence of various conventional condensation catalysts. The state of the cured product may range widely from rubber-like to resinous according to the molecular weight and main chain skeleton of the polymer. Therefore, this polymer can be utilized in sealing materials, adhesives, elastic adhesives, pressure sensitive adhesives, paints, powder coatings, foamed moldings, potting agents for electric and electronic use, films, gaskets, various molding materials and so forth. The terminal alkenyl-containing vinyl polymer of the present invention gives cured products either by itself or when an appropriate curing agent is used. In particular, the terminal (meth)acryloyl-containing vinyl polymer gives cured products upon heating in the presence of absence of various polymerization initiators. It is also crosslinked and cured upon light irradiation in the presence of various photopolymerization initiators. As the curing agent for the terminal alkenyl-containing vinyl polymer, various polyvalent hydrogensilicon compounds can be used. In that case, conventional hydrosilylation catalysts can be used as catalysts for the curing reaction. Curing of the terminal alkenyl-containing vinyl polymer of the present invention gives products widely ranging from rubber-like to resinous forms depending on the molecular weight and main chain skeleton thereof. Typical applications of the cured products include sealing agents, adhesives, pressure sensitive adhesives, elastic adhesives, paints, powder coatings, foamed moldings, potting agents for electric and electronic use, films, gaskets, various molding materials, artificial marbles and so forth. The terminal hydroxyl-containing vinyl polymer of the present invention is uniformly cured when a compound having two or more functional groups capable of reacting with the hydroxyl group is used as a curing agent. Typical examples of the curing agent are polyisocyanate compounds as having two or more isocyanato groups per molecule, methylolmelamines and alkyl ethers or low condensates thereof and like aminoplast resins, polyfunctional carboxylic acids and halides thereof, and the like. In producing cured products using these curing agents, appropriate curing catalysts may be used. Curing of the terminal hydroxyl-containing vinyl polymer of the present invention can give cured products ranging widely from rubber-like to resinous forms depending on the molecular weight and main chain skeleton thereof. Typical applications of the cured products include sealing materials, adhesives, pressure sensitive adhesives, elastic adhesives, paints, powder coatings, foamed moldings, potting agents for electric and electronic use, films, gaskets, various molding materials, artificial marbles and so on. The crosslinking silyl-, alkenyl- or hydroxyl-terminated vinyl polymer of the present invention is produced by utilizing the living radical polymerization technique and, therefore, shows a narrow molecular weight distribution. It has a lower viscosity as compared with those polymers produced by ordinary radical polymerization techniques and having an equivalent molecular weight, hence curable compositions containing it are expected to be easy to handle. |
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