MXPA97002791A - Polymerization process of radicals lib - Google Patents

Abstract

The present invention relates to a process for the polymerization of free radicals of olefinically unsaturated monomers, using a free radical initiator, the polymerization is carried out in the presence of a compound for carrying out molecular weight control, in which the compound for the molecular weight control is a chelate of CoII, of the following formula I: wherein each group X, independently in each ring and in different rings, is a substituent selected from alkyl of 1 to 14 carbon atoms and cycloalkyl of 6 to 14 atoms of carbon, n independently in each ring, is from 0 to 5 with the proviso that in at least one ring, n is from 1 to 5, Z independently in each boron atom, is selected from F, Cl, Br, OH, alkoxy of 1 to 12 carbon atoms, aryloxy of 6 to 12 carbon atoms, alkyl of 1 to 12 carbon atoms and aryl of 6 to 12 carbon atoms, or two Z groups taken together provide one or both of boron atoms, a upo -0- (Q) -0- where Q is a divalent aryl or a linking alicyclic group or an alkylene linking group, or two Z groups taken together on one or both of boron atoms, provide a linking group 1.5 -cyclooctanediyl, or being a CoIII analogue of the CoII chelate of formula I in which the Co-atom is covalently joined additionally, in a direction straight angles to the ring system of the macrocyclic chelate to H, to the halide or other anion, or a group homologously dissociable organic, and wherein at least optionally an additional ligand is coordinated to gamma, CoIi or CoIII, being a ligand or ligands which do not alter the valence state of the

Description

POLYMERIZATION PROCESS OF FREE RADICALS DESCRIPTION OF THE INVENTION The present invention relates to a process for the polymerization initiated by free radial monomer or olefinically unsaturated monomers in which the control of molecular weight is achieved by the presence of certain complexes of cobalt chelate. The invention also relates to the cobalt chelate complexes themselves and to a process for their production. Low molecular weight polymers, known as oligomers, are often desired for various applications (such as coating compositions) either in their own right or as precursors for other polymers. To form oligomers, it is necessary to properly control the polymerization process that is used to produce the type of product desired. In free radical polymerizations, which are widely used to polymerize olefinically unsaturated monomers, several conventional means are employed to control and limit the molecular weight of the growing polymer chains. Of these, the addition of the thiol compounds to the polymerization is likely to be used more extensively; the thiol acts as an effective chain transfer agent, but unfortunately it contaminates the system to which it has been added by virtue of its distinctive and persistent odor. More recently, attention has turned to the use of various transition metal complexes, particularly cobalt chelate complexes, such as chain transfer agents to be used in controlling molecular weight when olefinically unsaturated monomeric radicals are polymerized. For example, several literature references, such as N.S. Enikolopyan et al. J. Polym. Sci .. Polym. Chem. Ed., Vol 19. 879 (1981) describe the use of cobalt II porphyrin complexes as chain transfer agents in the polymerization of free radicals, while US 4526945 describes the use of cobalt II dioxime complexes for such a purpose Various other publications, for example US 4680354, EP-A-0196783 and US 4694059, describe the use of certain other types of cobalt II chelates as agents for chain transfer for the production of olefinically unsaturated monomer oligomers by polymerization of free radicals. WO-A-87/03605 on the other hand, claims the use of certain cobalt III chelate complexes for such purpose. Whether or not a particular cobalt chelate complex (or class of cobalt chelate complexes) is effective as a chain transfer agent in a radical unpredictable polymerization process; some are effective and some are not. It has now been discovered that the control of molecular weight in the free radical polymerization of olefinically unsaturated monomers can be effectively achieved with another class of cobalt chelate complexes, which have not been described in the prior art. In accordance with the present invention, a process for polymerizing free radicals of olefinically unsaturated monomer or monomers will be provided, (especially monomer or methacrylate monomers using a free radical initiator, the polymerization is carried out in the presence of a compound to effect the control of: molecular weight, the molecular weight control compound is a chelate of CoII of the following formula I: wherein each X group, independently in each ring and in different rings, is a substituent selected from alkyl of 1 to 14 carbon atoms and cycloalkyl of 6 to 14 carbon atoms; n independently in each ring, it is from 0 to 5 with the proviso that at least one ring n is from 1 to 5; Z independently on each boron atom, is selected from F, Cl, Br, OH, alkoxy of 1 to 12 carbon atoms, aryloxy of 6 to 12 carbon atoms alkyl of 1 to 12 carbon atoms and aryl of 6 to 12 carbon atoms; or two Z groups taken together on one or both carbon atoms, provide a group -O- (Q) -O- where Q is a divalent aryl or a linking alicyclic group or an alkylene linking group, or two Z groups taken together on one or both boron atoms, they provide a linking 1,5-cyclooctandiyl group; or is a ColII analogue of the Col I chelate of formula I in which the Co atom is covalently bonded additionally, in a direction at right angles to the ring system of the macrocyclic chelate to H, to the halide or other anion, or a homologetically dissociable organic group; and wherein at least one other ligand is coordinated to the ColI or CoIII atom, being a ligand or ligands which do not alter the covalence state of Co. Preferably X is alkyl of 1 to 14 carbon atoms, and may be Linear or branched chain if the option occurs. More preferably X is alkyl of 1 to 4 carbon atoms and particularly is methyl. It is possible for n (to represent the number of substituents in a ring) to be 0 in a ring or rings, (i.e., the ring is unsubstituted) with the proviso that at least one n ring is from 1 to 5. Preferably, n is from 1 to 5 in at least two rings, and more preferably is from 1 to 5 in at least three rings and in particular is from 1 to 5 in the four rings. Preferably n is 1 to 3 in a substituted ring, more preferably 1 or 2. Preferably, when n is 1 to 3 in a substituted ring it has the same value in each ring (if more than one ring is substituted) , and more preferably 1 or 2, and particularly 1 in each substituted ring. When n = 2, the substituents are preferably in positions 3, 4 or 2, 4. When n = 1, the substituents may be in positions 2, 3 or 4 of a ring, preferably they are in the same position in the rings replaced. It is particularly preferred that the substituent be in the 2, 3 or 4 position of the four rings, and especially in the 4 position of the four rings. The Z groups are preferably all the same (or when taken together to form a divalent group, such groups are the same in both boron atoms) and most preferably all are F. When both groups Z together provide a -O- group ( Q) -O- where Q is a divalent aryl or a linking alicyclic group, the Q group preferably has from 6 to 10 carbon atoms and in such cases the bond is from carbon atoms in the adjacent ring; more preferably Q is o-phenylene or 1,2-cyclohexanediyl. Where Q is alkylene, it preferably has the formula - (CR1-2,) '- m, - where each R is independently hydrogen or where x is from 1 to 12 and m is 2 or 3. Co chelates are considered to be Formula I are new and inventive compounds in their own right. Therefore, according to the invention, there is also provided a complex of Col I chelate of the formula I as defined above and also of the Col I I analogue of this complex as defined above. The chelates of Co of the invention are electrically neutral, the surrounding ligands providing a double negative charge to balance the Co2 + charge. Negative charges are thought to be delocalized instead of associated with any particular atoms. The specific cobalt chelates referred to for use in the invention (formulas shown in the following) are (3, 3'-dimethylbenzyldioxime diborodifluoride) of Coll having the formula II, (bis 2,2'-dimethylbenzyldioxime diborodifluoride) of Col I which has the formula III. (bis 2, 2 ', 4, 4' -tetramethylbenzyldioxime diborodifluoride) of Coll having the formula IV, and in particular, Coll (bis 4,4'-dimethylbenzyldioxime diborodifluoride) of Coll, which has the formula V: III (Formula II above shows, for convenience, the direction of ring numbering generally employed herein for compounds of formula I). The chelates of Co of the invention are all compounds for molecular weight control, effective when used in the process of the invention. Some of them, however, have particularly surprising and useful properties in certain circumstances. For example, the chelate compound of formula V is more surprisingly, much more effective at a lower molecular weight in water-based polymerizations (for example in both the emulsion and suspension polymerizations) and is also slightly more effective in the case of block or solution polymerizations, than the corresponding known compound in which all the rings are unsubstituted, ie (bis benzyldioxime diborodifluoride) of Coll, ie having the formula V, but with all the methyl groups replaced by H, such a chelate has been described in US 46794054 and perceived to be a very good CCTA catalyst. In this way it is possible to use a much smaller amount of the compound of formula V to achieve a given decrease in molecular weight in (particularly) aqueous polymerizations than that of the unsubstituted compound. Alternatively, a further decrease in molecular weight can be achieved using approximately the same amounts of the catalyst compounds. Therefore, the compound of formula V is, surprisingly, a fully active and exceptionally useful catalyst for decreasing molecular weight (ie solution and block polymerization as well as more particularly, in emulsion and suspension polymerization) . With respect to the invention, the chelates of Co apart from those of the formula V, these are also useful and all will effect the reduction of the molecular weight in polymerizations in aqueous base and in organic solvent, and in block (polymerizations in emulsion and suspension) although its effectiveness will vary somewhat according to the reaction medium that is employed (block, solvent, aqueous emulsion or aqueous suspension) and the Co chelate of the invention, in particular which is used. For example in the case of block polymerization, the substituted 3-methyl analog of the substituted 4-methyl compound, viz the compound of the formula II and also some of the higher alkyl homologs of the chelate of the formula V. viz those where the methyl groups are replaced at each 4-phenyl position by ethyl (structure VI: formula not shown) and isopropyl (structure VII: formula not shown), where it was found to be slightly more effective than the known completely unsubstituted compound mentioned in the foregoing (ie, bis-benzyldioxime diborodifluoride) of Coll. On the other hand, the efficacy of the 2-methyl analog of compound V (structure III, formula shown above) was found to be slightly worse than the compound completely unsubstituted in the block polymerization, whereas the analog 4-ter -butyl (structure VIII, formula not shown) was found to be approximately the same. In the case of the aqueous suspension polymerization, it was found that these other compounds of the invention (ie apart from that of the formula V, as mentioned in the above) also have significantly improved effectiveness compared to the Co-chelate compound. unsubstituted, apart from the 2-methyl compound of the formula III, which has approximately the same effectiveness as the unsubstituted compound (although this may have been due to the compound of the formula III as used in its preparation which is a bit impure ). In the case of aqueous emulsion polymerization, however, it was found that the 2- or 3-methyl analogues of V (viz II and III) were usually more effective than the completely unsubstituted compound (although the results were variable at this respect), although the higher alkyl homologs of V, viz VI, VII and VIII (see above) were distinctly less effective than the completely unsubstituted compound - but nevertheless still resulted in reduced molecular weight compared to polymerization in the absence of a Co-catalyst With respect to the Col11 analogues of the compounds of the formulas, these are produced when the Co is additionally linked to another atom, ion or organic group, which is homolytically dissociable, such as H, Cl- 10 optionally substituted, cyano, halide, ester, aryl of C6-? Or (including aryl of heterocyclic cg-10) and alicyclic of c6-10 (including alicyclic of Cfi-10 heterocyclic), such as another group that it is usually located in an axial position (ie perpendicular to the equatorial ligands shown in the above formulas). Analogous CoIII complexes are preferred in which CoIII is reducible to Coll under the conditions of polymerization. Axial groups such as halogen and H may be particularly suitable. Other possible particularly suitable groups include axial alkyl groups (preferably 1 to 10 carbons) bearing one or more substituents on the carbon atoms attached to the metal ion; such substituents may include nitrile, ester and optionally substituted aromatic groups. Some of these CoIII complexes can be stable materials under ordinary storage conditions and can only react under conditions that generate free radicals from the polymerization process. Others, particularly where H is another group (axial), can be highly reactive intermediary species - and indeed it is possible that all Coll complexes (and possibly also CoIII ones) exert their chain transfer effect through the procedure through of the reactive CoIIIH intermediary. It is also possible that there is always a periodic exchange between the valence states of Coll and CoIII in the complexes during the polymerization. In fact, the actual mechanism involved is complex and not properly understood on our part we do not wish to be bound to any particular theory nor to an identification of the specific chemical constitution or valence state of the Co complex during the process of; real polymerization. It is also possible for the cobalt complexes as defined above (ie complexes of Coll or CoIII) to additionally have other ligands (normally one or two) to coordinate the Co atom (supposedly axial), which does not alter the state of valence of Co. These can be derived by passing the reaction medium used in the preparation of the Co complex or the polymerization medium used in the polymerization process, or it can be derived by deliberately adding a compound, which will provide such ligands and is frequently the case that the coordinated presence of the same in the complex, will mitigate the effectiveness of the latter. However, it is not essential for the invention and for convenience they have not been shown in the various formulas written in the foregoing. Typical of such additional ligands are weakly tertiary amines; basic such as pyridine (or its substituted derivatives), trialkylamines, dialkylamines, ethers such as tetrahydrofuran and diethyl ether, alcohols such as methanol and also optionally trialkyl, triallyl or substituted tri (alkyl-aryl) phosphines (or analogous compounds such as alkoxy or corresponding aryloxyphosphines). (Such alkyl or alkoxy groups preferably and independently, have from 1 to 10 carbons and such aryl or aryloxy groups preferably and independently, have from 1 to 10 carbons and such aryl or aryloxy groups preferably and independently, have from 6 to 10. carbon atoms). One or more water molecules may also be coordinated to the Co complex. The defined cobalt chelate compounds allow efficient production of oligomers and are considered to be functioning as chain transfer agents. As mentioned in the above, some members within the defined scope are exceptionally active in aqueous polymerizations. Generally speaking, the degree of polymerization of such oligomers (generally in the case of copolymers) will usually be in the range of 2 to about 500 (ie, 2 to 500 polymerized units), preferably 2 to 300 and greater preference from 5 to 200. The polymerization process can be carried out in the presence of a polymerization medium (which acts as a carrier medium for the components and as a heat transfer medium) or in the absence of such a medium (i.e. In block) . When a polymerization medium is used, the polymerization can be, for example, a solution polymerization (using organic solvent), an aqueous suspension or emulsion polymerization, a non-aqueous dispersion polymerization. It is also possible to carry out the polymerization process in the presence of a preformed polymer (such as a polyester or polyurethane) which may be dispersed in water or other dispersion medium to produce a composite material of the preformed polymer and the product of the process of polymerization. Typical organic solvents that can be used as the medium for polymerization include aromatic hydrocarbons such as benzene, toluene and the xylenes; ethers such as diethyl ether, tetrahydrofuran, alkoxylated ethylene glycol or polyethylene glycol; alcohols such as methanol, ethanol, propanol and butanol and their esters with carboxylic acids such as acetic acid, propionic acid and butyric acid, ketones such as acetone or methyl ethyl ketone; and liquid tertiary amines such as pyridine. Mixtures of solvents can be used. The water can also be used as a polymerization medium (sometimes in combination with a solvent or solvents, usually miscible in water, examples of which are described in the above) as in suspension or emulsion polymerizations and for such processes conventional emulsification or suspension agents (stabilizers) may be employed. The techniques of emulsion polymerization and aqueous suspension are in their basic format, extremely well known and do not need to be described in great detail. Suffice it to say that such processes involve dispersing the monomer or monomers in an aqueous medium and carrying out the polymerization using a free radical initiator (frequently soluble in water in the case of emulsion polymerization and frequently soluble monomer in the case of suspension polymerization) and (usually) appropriate heating (for example 30 to 120 ° C, more usually 45 to 90 ° C) and the agitation (stirring) that are employed. An aqueous emulsion polymerization can be carried out with conventional emulsifying agents (surfactants) which are used [for example anionic and / or nonionic emulsifiers such salts of Na, K and NH ^ of dialkylsulfosuccinates, salts of Na, K and NH4 of sulphated oils, salts of Na, K and NH ^ of alkylsulfonic acids , alkyl sulfonates of Na, K and H4 such as Na lauryl sulfate, alkali metal salts of sulfonic acids, Ci2-24 fatty alcohols ethoxylated fatty acids and / or fatty amides and salts of Na, K and NH ^ of fatty acids such as Na stearate and Na oleate; Aryl-containing analogs of the alkyl-containing surfactants are also useful; other surfactants include phosphates and cationic compounds such as hexadecyltrimethylammonium bromide. Nonionic emulsifiers based on ethoxylate chains may also be useful. Other emulsifiers that have both ionic and non-ionic character can be used. The amount used is usually 0.2 to 15% by weight, more usually 0.3 to 5% by weight, based on the weight of total monomers charged]. In the case of acrid suspension polymerization, protective colloids are usually employed as stabilizers, examples of which include partially hydrolyzed polyvinyl acetate (varying degrees of hydrolysis), cellulose derivatives, polyvinylpyrrolidone and polyacrylic acid. The amount used is usually 0.1 to 8%, more usually 0.1 to 5%, calculated on the weight of the monomer. Salts such as Na 2 SO 4 may be included to reduce the solubility of the monomer in the aqueous phase and to improve the stabilization. Polymerizations (i.e. in general, including block polymerization, in solution, as well as aqueous suspension or emulsion and non-aqueous dispersion polymerization) are usually carried out at a temperature within the range of 25 to 160 ° C (more usually from 45 to 90 ° C). Any initiator that produces suitable free radicals, appropriate for the type of polymerization process employed, can be used in the process of the invention, the usual criteria being that it has acceptable solubility in one or more of the other polymerization components (eg solvent, monomer or monomers, or water), which is sufficiently active at the polymerization temperature (usually having a half-life in the range of 0.5 to 5 hours) and does not unacceptably affect the stability for the Co-chelate. Examples of such initiators that produce free radicals include azo compounds such as 2,2'-azobis (isobutyronitrile) (AIBN), 2,2'-azobis (2-ethyl) butanonitrile, 4,4'-azobis (4-azobis) cyanovaleric), 2- (t-butylazo) -2-cyanopropane, 2,2'-azobis [2-met il-N- (1, 1) -bis (hydroxyethyl] -propionamide and 2, 2'-azobis [2 -methyl-N-hydroxyethyl)] -propionamide. Other free radical initiators can also be used, examples of which include peroxy compounds such as benzoyl peroxide, lauroyl peroxide, hydrogen peroxide and persulfates of Na, K and NH4. Other useful peroxy initiators include peroxyesters, particular examples of which are tert-butyl peroxy-2-ethylhexanoate and ter-amyl peroxy-2-ethylhexanoate. The redox initiator systems can also be used, examples of which include redox couples such as NH 4 persulfate and Na metabisulfite and tert-butyl hydroperoxide (TPHPO) and iso-ascorbic acid. The amount of initiator will depend, among other things, on the type of polymerization (block, solution, aqueous emulsion, aqueous suspension or non-aqueous dispersion), but in general, it will usually be within the broad range of 0.05 to 15%, based on the weight of the charged monomer or total monomers. (An initiator, for example NH 4 persulfate may optionally be added at the end of the polymerization to remove the residual monomer). The use of Co chelates defined as compounds for the control of molecular weight in the process of the invention avoids the requirement of using conventional chain transfer agents, which often have disadvantages of one kind or another. For example, mercaptans impart a pronounced odor, while halogenated hydrocarbons (such as bromoform or carbon tetrachloride) are environmentally suspect. Furthermore, the thiols are incompatible with certain monomers (such as glycidyl methacrylate) which are useful in applications such as crosslinkable powder coatings. The defined Che chelates, which act to control molecular weight, can be used in a very low amount (because it acts in a catalytic form) compared to conventional chain transfer agents to achieve comparable molecular weight reduction . (Some can be used in an exceptionally low amount as mentioned in the above). This allows a much purer product to be prepared. The process of the invention can be carried out using an "all-in-one" batch process in which the components are present in the reaction medium at the beginning of the polymerization or a semi-batch process in which one or more of the components used (usually at least one of the monomers) is completely or partially fed to the polymerization medium during the polymerization. The chelates used in the process can be prepared in advance or they can be formed in itself from the appropriate reagents. The amount of cobalt chelate used in the polymerization process will depend on the desired molecular weight of the oligomer to be produced and other factors including the monomer composition and polymerization conditions that are employed. Therefore, the amount of cobalt chelate used can cover a wide range, such that usually the molar ratio of monomer or monomers to cobalt chelate will be within the range of 10,000,000 / 1 to 50/1 and more typically of 1,000,000 / 1 to 5,000 / 1. In the polymerization process the molar ratio of the monomer or monomers to free radical initiator will usually be within the broad range of 4,000 / 1 to 10/1 and more typically from 1,000 / 1 to 30/1. The process of the invention is more effectively applied to the homo- and copolymerization of methacrylate esters (copolymerization which is with any suitable comonomer or comonomers, such as a different methacrylate ester or styrene) and also to the homo- and copolymerization of styrenes (the copolymerization which is with any suitable comonomer or comonomers such as a different styrene or a methacrylate ester). The acrylate esters can also be polymerized, particularly if they are included as comonomers with ethacrylic esters and / or styrenes. The process of the invention has a particular utility that can be used for the polymerization of the acid functional monomers (which for example can be included as comonomers in the copolymerization of methacrylate ester or styrene). Examples of monomers that can be polymerized include methyl methacrylate, ethyl methacrylate, butyl methacrylate (all isomers), and other alkyl methacrylates (e.g., above 14 carbon atoms).; corresponding to acrylates: also functionalized methacrylates and acrylates including glycidyl methacrylates, trimethoxysilylpropyl methacrylate, allyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dialkylaminoalkyl methacrylates (preferably 1-4 carbon alkyl) and acetoacetoxy esters of acrylates of hydroxyalkyl and methacrylates such as acetoacetoxyethyl ethacrylate; fluoroalkyl (meth) acrylates, methacrylic acid; acrylic acid; fumaric acid (and esters), itaconic acid (and esters), maleic anhydride, styrene, α-methylstyrene and other styrene derivatives such as styrene-p-sulfonic acid and isomers thereof, 4-chlorostyrene and isomers thereof, and 4-bromostyrene and isomers thereof; vinyl halides such as vinyl chloride and vinyl fluoride; vinyl esters such as vinyl, vinyl acetate; acrylonitrile; methacrylonitrile; vinylidene halides of the formula CH2 = C (Hal) 2 where each halogen is independently Cl or F; optionally substituted butadienes of the formula CH2 = C (R2) C (R2) = CH2 where R2 is independently H, Cl for CIO alkyl, Cl or F; sulphonic acids or derivatives thereof of the formula CH2 = CHS02OM wherein M is Na, K, Li, N (R3) 4, R3 or - (CH2) 2-D where each R3 is independently H or C1-C10 alkyl , D is C02G, OH, N (R3) 2 or S02OG and G is H, Li, Na, K or N (R) 34; acrylamide or its derivatives of the formula CH2 = CHCON (R2) 2; and methacrylamide or its derivatives of the formula CH 2 = C (CH 2) CON (R 2) 2 and a keto group containing amides such as diacetone acrylamide. Mixtures of such monomers can be used, for example to form bi or multicopolymers. Preferred monomers are C1-C10 alkyl methacrylates and acrylates, methacrylic acid and / or acrylic acid, styrene, styrene derivatives, methacrylates and hydroxyalkyl C1-C14 acrylates, such as hydroxyethyl methacrylate and hydroxypropyl methacrylate, methacrylates of C 1 -C 14 epoxyalkyl and acrylates such as glycidyl methacrylate. Oligomers prepared using the process of the invention employing the defined Co chelate catalyst are useful in a variety of applications. They are particularly suitable for use in coating applications, in which they, or products derived from or including them, can provide a key part of the coating compositions or formulations that are employed. Such coating compositions which may be pigmented or non-pigmented include: water-based coating compositions, particularly when the oligomer has been derived from the aqueous emulsion polymerization; coating compositions based on organic solvent, particularly of high solids content; and powder coating compositions. The solvent-based and powder-based coating compositions preferably employ oligomers made using an aqueous suspension polymerization or solution polymerization of organic solvent. The coating compositions can be used to coat a variety of substrates, for example metals, wood, paper, cardboard, cementitious materials, polymeric films or other plastic articles. Another use for the oligomers made by the process of the invention, are the applications of the graphic arts in which they, or products derived from them, can provide important components of water-based or solvent-based inks and overprint varnishes. Still another use for the oligomers made by the process of the invention is in adhesive applications, in which they, or products derived therefrom, can be employed in pressure sensitive adhesive compositions, which melt with heat, by contact and by lamination. Such adhesive compositions may be water based, organic solvent based or heat melting type. As mentioned in the above, the process of the invention is particularly suitable for incorporating acid functional monomers (such as methacrylic acid) into the oligomer. If it is present in a sufficient amount, such as a monomer which will become a hydrophilic oligomer or still soluble in water when the acid groups are in salt form (for example upon being neutralized). Such a water-dispersible or water-soluble oligomer has many uses - see, for example, the disclosure of WO95 / 04767, in which the water-soluble oligomer is used in the formation of a multi-phase polymer system, in which An emulsion polymerization to form the hydrophobic polymer is carried out in the presence of the hydrophilic oligomer. Such multi-phase products have uses, for example in water-based ink and overprint varnishes. Also as mentioned in the above, the process of the invention is very suitable for incorporating the functionality in the oligomer, by means of the use of functional monomers as part of the monomer system used for the oligomer. Examples of such functional monomers include allyl, glycidyl, or hydroxyalkyl methacrylates or acrylates (for example hydroxyethyl), as well as ketofunctional monomers such as the acetoacetoxy esters of hydroxyalkyl acrylates and methacrylates, such as acetoacetoxyethyl methacrylate and also amides containing keto such as diacetone acrylamide. One of the purposes of using the functional monomer is to provide subsequent cross-linking ability in the resulting oligomer or polymer system derived therefrom. The present invention is now illustrated but not limited by reference to the following examples. Unless otherwise specified, all parts, percentages and relationships are on a per-weight basis. The prefix C before an example means that it is comparative. In the example, the following abbreviations and terms are specified: MMA methyl methacrylate MAA methacrylic acid STY styrene EMA ethyl methacrylate EA ethyl acrylate HPMMA hydroxypropylmethylacrylate GMA glycidyl methacrylate PMMA polymethyl methacrylate Me methyl or Et ethyl iPr isopropyl tertiary butyl AIBN 2,2 ' azobis (isobutyronitrile) CVA 4,4'-azobis (4-cyanovaleric acid) BPO benzoyl peroxide CCTA catalytic chain transfer agent THF: tetrahydrofuran CoPhBF: (bis benzyldioxime diborodifluoride) from Coll Co4-MePhBF: (bis 4, 4 ' -dimethylbenzyldioxime diborodifluoride) of Coll Co3-MePhBF: (bis 3, 3'-dimethylbenzyldioxime diborodifluoride) of Coll Co2-MePhBF: (bis 2, 2'-dimethylbenzyldioxime diborodifluoride) of Coll Co4-EtPhBF: (bis 4,4'-diethylbenzyldioxime diborodifluoride) of Coll Co4-iPrPhBF: (bis 4,4'-diisopropylbenzyldioxime diborodifluoride) from Coll Co4-tBuPhBF: (bis 4,4'-diterbutylbenzyldioxy to dib Ordifluoride) by Coll SLS: sodium lauryl sulphate Mn: average molecular weight number Mw: average molecular weight weight PDi: (Mw / Mn (polydispersity index) Dowfax 2A1: anionic surfactant (supplied by Dow Chemical Co. as a 50% aqueous solution) GPC: gel permeation chromatography MEK: methyl ethyl ketone General Procedures (i) Synthesis of Cobalt CCTA All substituted benzyl are prepared following the procedure shown in Org. Syn. Coll Vol 1, page 87. All dioxies are prepared using the method described by Brady and Perry, JCS 2874-2882, 1925. The following general method is used to prepare cobaloximes of the present invention, the method here exemplifies the preparation of several Coll compounds of the formula I [with n = 1 and X = alkyl in each benzene ring, and each Z == F] as typical: The appropriate dialkylbenzyldioxime (2 mol equivalents) is stirred together with cobaltacetate tetrahydride (1 mol equivalent) and diethyl ether (approximately 70 mol equivalents) under an atmosphere of deoxygenated dinitrogen. Eroste boron trifluoride (10 mole equivalents) is introduced into drops over a period of 15 minutes, making sure that the reaction temperature does not exceed 5 ° C. At the end of the addition of the reaction mixture it is kept under 5 ° C for an additional 10 minutes. The mixture is then heated slowly to 40 ° C and maintained at this temperature for 15-90 minutes. The mixture is then cooled to 0 ° C and sodium carbonate (between 1.25 and 4 mol equivalents) is added. The mixture is stirred for an additional 30 minutes, then methanol (approximately 10 mol equivalents) is added. The resulting solid is isolated by filtration, washed with water to remove the inorganic materials and finally washed with methanol (approximately 20 mol equivalents) to produce the product as the dimethanol complex (Formula IX).

The results are summarized in the following Table: TABLE I * formula written in the above ** unwritten formula (ii) Block Polymerization [The following procedure is written in terms of homopolymerizations of MMA but muta tis mu tandie is equally applicable to the preparation of the copolymers]. The MMA was deoxygenated by bubbling nitrogen through and for 1 hour before use. An amount of CCTA is accurately weighed in a round bottom flask. The flask is evacuated and filled with nitrogen at least three times. The MMA is added by means of a syringe to form a CCTA supply solution with a typical concentration of approximately 2 x 10"4 moles dm ~ 3. AIBN is added (0.085 g) to each of many Schlenck tubes which are then evacuated and filled with nitrogen at least three times. Several aliquots of MMA and the CCTA supply solution are added to each Schlenck tube by means of a syringe in such a way that the total volume was 10 ml in each case and the molar ratio of CCTA / MMA was in the range of 0 to 2.2 x 10 ~ 6. Each tube was heated to 60 ° C by means of a thermostatically controlled water bath. After half an hour a sample is removed from each tube and stopped by the addition to a solution of hydroquinone in THF. The molecular weight of the polymer formed was determined by GPC in relation to PMMA standards. (iii) Polymerization in Solution To a Schlenck tube of 200 ml filled with dry nitrogen and 0.085 g of AIBN are added the appropriate amounts of the monomers (typically 10 ml of MMA) and 20 ml of the appropriate solvent, all of which have been previously sprayed with dry nitrogen. The desired amount of cobalt catalyst is then added and the tube is heated to 60 ° C under nitrogen. A sample is removed after half an hour as described above for block polymerization or sometimes after one hour. (iv) Suspension Polymerization The following procedure was used. 1) A 3 liter round bottom glass reaction vessel adapted with a cooled water condenser is purged with nitrogen for not less than 1 hour before starting the polymerization. 2) Sodium sulfate (0.2% by weight based on total monomer) and polyacrylic acid (2% by weight based on the total monomer of a 12.5% by weight solution in water) is added to the reaction vessel, followed for 1,200 ml of distilled water. The mixture is completely stirred with a stainless steel blade agitator. 3) Using a thermostatically controlled water bath, the contents of the reaction vessel is heated to 70 ° C. 4) The selected monomers totaling 400 g are weighed in a covered container followed by an initiator (for example, AIBN or BPO in the range of 0.2-1% by weight based on total monomer) and CCTA (typically 15 to 100 ppm by weight based on total monomer mass). The mixture is then transferred to the reaction vessel with continuous agitation and results in a decrease in temperature. The temperature rises to either 75 ° C or 80 ° C and is maintained at that value (+/- 2 ° C) throughout the reaction. 5) 10 ml of a 2.5% aqueous solution by weight of Airvol V540 (a hydrolyzed polyvinyl acetate partially supplied by Air Products) is added to the reaction vessel one hour after the contents have reached 75 ° C. 6) Ammonium persulfate (0.125% by weight based on the mass of total monomer) is added two hours after the formation of hard beads in the reaction vessel. The temperature is then increased by 5 ° C and maintained at that temperature. An equivalent amount of ammonium persulfate is added thirty minutes after the first addition. The reaction is allowed to proceed for another thirty minutes. 7) The contents of the reactor were cooled to less than 32 ° C. The beads are separated from the water by filtration, washed with excess water and dried in an oven at approximately 40 ° C. 8) The molecular weight of the polymer formed was determined by GPC in relation to the PMMA standards. (vi) Emulsion Polymerization All monomers and water degas (deoxygenated) passing a stream of nitrogen through them for at least one hour before use. The polymerizations were carried out under a nitrogen atmosphere in a one-liter round-bottomed flask with a mechanical agitator. The deionized, deoxygenated water and the surfactant are charged to the reaction vessel which is heated to 75 ° C and stirred. A heavy amount of CCTA cobalt is added to a separate flask. The flask is evacuated and nitrogen is flooded three times. The monomer or monomers are added to the flask containing CCTA and dissolved CCTA with stirring. CVA and another small portion of deionized water (typically 30 g) are added to the reaction vessel. The solution of the cobalt catalyst in the monomer mixture is fed to the reaction vessel using a syringe attached to a syringe pump at a linear speed for a period of either 1 or 2 hours. The temperature in the reaction flask is maintained at 75 ° C during the feeding time and during this time another 4 hours before cooling to room temperature. All molecular weights were measured by Gel Permeation Chromatography (GPC) with either CHCl3 or THF as eluent, against PMMA standards unless otherwise indicated.

Examples 1 to 8, C9, CIO Block Polymerizations The general procedure described above for the block homopolymerization of MMA was followed and the representative results are given in Table 2. The Mn are those after 0.5 hours of polymerization. [MMA] / [Co] means the relative amounts of monomer (MMA) and catalyst Co on a molar basis.

TABLE 2 * where it was written ** Examples 1, 2 and 3 were different polymerizations.

It will be noted that for the most part, the catalysts of the invention were more effective (at about the same level of Co catalyst relative to the monomer) in the block polymerization than corresponding unsubstituted CoPhBF; the exceptions where Co4-t-BuPhBF which had approximately the same effectiveness in reducing molecular weight and Co2-MePhBF which was not as good as CoPhBF (although it was still effective as a CCTA).

Examples Cll to C13, 14 to 16 Polymerization in Solution The general procedure for the MMA solution homopolymerization described above is followed and the results are given in Table 3. The number of average molecular weights (Mn) are indicated after 1 hour.

[MMA] / [Co] means the relative amounts of the monomer (MMA) and the catalyst on a molar basis.

TABLE 3 It was found that the invention Co CCTA Co4-PhBF was slightly more effective in MEK solution than the compound without CoPhBF substitution corresponding to the same catalyst levels in relation to the monomer.

Examples 17 to 19, C20 Polymerization in Solution In this example the styrene was homopolymerized in MEK solvent according to the general procedure described in the above. The Mn were determined after 0.5 hours.

The results are given in Table 4 TABLE 4 The CCTA invention used in this way was found to be effective in controlling molecular weight during styrene polymerizations.

It can be mentioned that the block and solution polymerization exemplified in the above, where the molecular weights were measured after 0.5 or 1 hour, can be allowed to proceed to high conversion, while still achieving similar reduction in molecular weight.

Examples 21 to 27, C28 to C30. 31 to 36, C37, 38 to 43 Emulsion Polymerization The general procedure for emulsion polymerizations was followed. The results are shown in Table 5 below. The results demonstrate the exceptional activity of Co4-MePhBF in aqueous emulsion polymerization, with a clear advantage compared to the catalyst without replacing CoPhBF. The Co3-MePhBF and Co2-MePhBF catalysts were also effective in reducing molecular weight but less than Co4-MePhBF and are more variable in effect (usually more effective than CoPhBF but on one occasion for the 3 -Me isomer, it is less) . However the higher homologs (for example Co4-EtPhBF, Co4-iPrPhBF and Co4-tBuPhBF) although still provide reduction in molecular weight in the emulsion polymerization were considerably less effective than Co4-MePhBF (and also CoPhBF for this matter).

TABLE 5 or TABLE 5 (continued) > Examples 44 to 55, C56 to C60, 61 to 63 Suspension Polymerization The general procedure for suspension polymerization described in the above, was followed and the results are shown in Table 6. In most cases, the experiments were doubled to verify consistency. All the ATCCs of the invention tested were found to be highly effective in the polymerization in aqueous suspension in the reduction of molecular weight in the homopolymerizations of MMA and copolymerizations containing BMA and MAA using the AIBN primer (compare Example C56 which has an absence of CCTA and Examples 44-55 using the CCTAs of the invention). The amounts of each CCTA used in Examples 46-55 was equivalent on a molar basis, such that in these examples, the molar ratio of MMA / CCTA was about 300,000. It can easily be seen that with the exception of Co2-MePhBF (III) in Examples 54 and 55, the molecular weights in Examples 46-55 are very similar indicating a similar chain transfer activity for each CCTA. The results for Co4-MePhBF seem to be the best in aqueous suspension polymerization yet by far. The lower degree of molecular weight reduction when Co2-MePhBF (III) is used is in line with the lower value obtained in the block polymerizations and may in both cases possibly be related to their lower purity. Comparisons with CoPhBF are provided in Examples C57-C60. With the exception of Co2-MePhBF (III) the molecular weight reductions were significantly greater, when the CCTAs of the invention are used than when CoPhBF is used that is an average Mn of approximately 2,400 compared to 5,500. Two different batches of CoPhBF prepared several times and at different sites were used in Examples C57-C60 to ensure that the data were genuine and thus support that the higher Mn were obtained with CoPhBF than with Co4-MePhBF at the same molar level and using the same monomer system and the same free radical initiator (AIBN). The Examples 44, 45 demonstrate that the reduction in effective molecular weight in aqueous suspension polymerization can be achieved using thermonomer systems (MMA / BMA / MAA), although the molecular weight reduction was not as great as when MMA is used alone (other conditions than they are comparable). A few examples (Examples 61-63) were made using BPO as the free radical initiator to demonstrate utility with a non-azo initiator.

BOARDS

Claims (44)

1. A process for the polymerization of free radicals of olefinically unsaturated monomer or monomers, using a free radical initiator, the polymerization is carried out in the presence of a compound to effect molecular weight control in which the compound for the control of molecular weight is a chelate of Coll, of the following formula I: characterized in that each group X, independently in each ring and in different rings, is a substituent selected from alkyl of 1 to 14 carbon atoms and cycloalkyl of 6 to 14 carbon atoms; n independently in each ring, is from 0 to 5 with the proviso that in at least one ring, n is from 1 to 5; Z independently on each boron atom, is selected from F, Cl, Br, OH, alkoxy of 1 to 12 carbon atoms, aryloxy of 6 to 12 carbon atoms, alkyl of 1 to 12 carbon atoms and aryl of 6 to 12 carbon atoms; or two Z groups taken together provides one or both boron atoms, a group -0- (Q) -0- where Q is a divalent aryl or a linking alicyclic group or an alkylene linking group, or two Z groups taken together on one or both boron atoms provide a 1,5-cyclooctanediyl bond group; or is a Col 11 analogue of Coll chelate of formula I in which the Co atom is covalently bonded additionally, in a direction at right angles to the ring system of the macrocyclic chelate to H, to the halide or other anion, or a homologetically dissociable organic group; and wherein optionally at least one other ligand is coordinated to the Coll or CoIII atom, being a ligand or ligands which do not alter the Covalence state of Co.

2. The process in accordance with the claim 1, characterized in that X is alkyl of 1 to 4 carbon atoms.

3. The process in accordance with the claim 2, characterized in that X is selected from the group of methyl, ethyl, isopropyl and tertbutyl, and methyl is preferred.

4. The process according to any of claims 1 to 3, characterized in that n is from 1 to 3 in each ring.

5. The process according to any of the preceding claims, characterized in that n has the same value in each ring.

6. The process according to any of the preceding claims, characterized in that n = 1 or 2 in each ring, more preferably 1 in each ring.

7. The process according to claim 1, characterized in that X is methyl in each ring and n = 1 in each ring.

8. The process according to claim 1, characterized in that X is the same in each ring and is selected from ethyl, isopropyl and tertbutyl and n = 1 in each ring.

9. The process according to either claim 7 or claim 8, characterized in that X is in position 4 in each ring.

10. The process according to either claim 7 or claim 8, characterized in that X is e the same position in each ring and is either in position 2 or 3.

11. The process according to any of the preceding claims, characterized in that each Z is F.

12. The process in accordance with the claim 1, characterized in that the chelate of Coll has n = 1 in each ring, X is methyl in each ring and is located in position 4 of each ring, and each Z is F.

13. The process in accordance with the claim 1, characterized in that the chelate of Coll has n = 1 in each ring, X is methyl in each ring and is located in position 3 of each ring, and each Z is F.

14. The process in accordance with the claim 1, characterized in that the chelate of Coll has n = 1 in each ring, X is methyl in each ring and is located in position 2 of each ring, and each Z is F.

15. The process according to any of the preceding claims, characterized in that the polymerization process is a polymerization process in an aqueous suspension.

16. The process according to any of claims 1 to 14, characterized in that the polymerization process is a polymerization process in an aqueous emulsion.

17. The process according to any of claims 1 to 14, characterized in that the polymerization process is a volume polymerization process.

18. The process according to any of claims 1 to 14, characterized in that the polymerization process is a polymerization process in a solution of an organic solvent.

19. The process according to any of claims 1 to 14, characterized in that the polymerization process is a polymerization process in a non-aqueous dispersion.

20. The process according to any of the preceding claims, characterized in that the polymerization process is carried out in the presence of preformed polymers, preferably a polyester or a polyurethane.

21. The process according to any of the preceding claims, characterized in that the process is applied to the homo- or copolymerization of methacrylate esters, the copolymerization is carried out with any suitable comonomer or comonomers, such as a different methacrylate ester and / or styrene or the homo- or copolymerization of styrenes, the copolymerization is carried out with any of the suitable comonomers, such as a different styrene and / or a methacrylate ester.

22. The process according to claim 21, characterized in that the monomer system employed includes an acrylate ester or esters.

23. The process according to any of the preceding claims, characterized in that the monomer system employed includes an acid functional monomer, preferably it is one or both of the methacrylic acid and acrylic acid.

24. The process according to any one of claims 1 to 20, characterized in that the polymerized monomers are selected from at least one of the methacrylates or alkyl acrylates of cyclohexydiacrilate and hydroxyalkyl acrylates of Ci-i? 'C 1-14 alkyl epoxy methacrylates and acrylates, methacrylic acid, acrylic acid, styrene and styrene derivatives.

25. The process according to any of claims 1 to 20, characterized in that the polymerized monomer is selected from at least methyl methacrylate, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers); the corresponding acrylates; methacrylates and functionalized acrylates selected from glycidyl methacrylate, trimethoxysilylpropyl methacrylate, allyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dialkylaminoalkyl methacrylate and acetoacetoxyethyl methacrylate; fluoroalkyl (meth) acrylates, methacrylic acid; acrylic acid; fumaric acid (and esters), itaconic acid (and esters), and maleic anhydride, styrene, α-methylstyrene, and vinyl chloride and vinyl fluoride; vinyl acetate; acrylonitrile; methacrylonitrile; vinylidene halides of the formula wherein each halogen is independently Cl or F; optionally substituted butadienes of the formula CH 2 = C (R 2) C (R 2) = CH 2 where R 2 is independently H, Cl to CIO alkyl, Cl or F; sulphonic acids or their derivatives of the formula CH2 = CHS02OM wherein M is Na, K, Li, N (R3) 4, R3 or - (CH2) 2 ~ D where each R3 is independently H or alkyl from Cl to CIO, D is C02G, OH, N (R3) 2 or S02OG and G is H, Li, Na, K or N (R3) 4; acrylamide or its derivatives of the formula CH2 = CHCON (R3) 2, methacrylamide or its derivatives of the formula CH2 = C (CH3) C0N (R3) 2, diacetone-acrylamide and mixtures of such monomers.

26. An oligomer produced using a process according to any of the preceding claims.

27. The use of an oligomer according to claim 26, in coating applications, graphic arts applications, and adhesive applications.

28. A chelate Coll of the following formula I: characterized in that each group X, independently in each ring and in different rings, is a substituent selected from alkyl of 1 to 14 carbon atoms and cycloalkyl of 6 to 14 carbon atoms; n independently in each ring, is from 0 to 5 with the proviso that at least one ring, n is from 1 to 5; Z independently on each boron atom, is selected from F, Cl, Br, OH, alkoxy of 1 to 12 carbon atoms, aryloxy of 6 to 12 carbon atoms, alkyl of 1 to 12 carbon atoms and aryl of 6 to 12 carbon atoms; or two Z groups taken together provide a group of one or both boron atoms, a group -O- (Q) -0- where Q is a divalent aryl or a linking alicyclic group or an alkylene linking group, or two groups Z taken together on one or both boron atoms, providing a 1,5-cyclooctanediyl group; or is a Col11 analog of Coll chelate of formula I in which the Co atom is covalently bonded additionally, in a direction at right angles to the ring system of the macrocyclic chelate to H, to the halide or other anion, or a homologetically dissociable organic group; and wherein at least one other ligand is coordinated to the Coll or CoIII atom, being a ligand or ligands which do not alter the Covalence state of Co.

29. A Coll chelate according to claim 28, characterized in that X is alkyl of 1 to 4 carbon atoms.

30. The Coll chelate according to claim 29, characterized in that X is selected from methyl, ethyl, isopropyl, and tertbutyl, and methyl is preferred.

31. The Coll chelate according to any of claims 28 to 30, characterized in that n is from 1 to 3 in each ring.

32. The Coll chelate according to any of claims 28 to 31, characterized in that n has the same value in each ring.

33. The Coll chelate according to any of claims 28 to 32, characterized in that n = 1 or 2 in each ring, more preferably 1 in each ring.

34. The Coll chelate according to claim 28, characterized in that X is methyl in each ring and n = 1 in each ring.

35. The Coll chelate according to claim 28, characterized in that X is the same in each ring and is selected from ethyl, isopropyl and tertbutyl and n = 1 in each ring.

36. The Coll chelate according to either claim 34 or claim 35, characterized in that X is in position 4 in each ring.

37. The chelate according to either claim 34 or claim 35, characterized in that X is in the same position in each ring and is in either position 2 or in position 3.

38. The Coll chelate according to any of claims 28 to 37, characterized in that each Z is F.

39. Coll chelate, characterized because it has the following formula V:

40. Coll chelate, characterized because it has the following formula II:

41. Coll chelate, characterized because it has the following formula III:

42. The chelate Co according to any of claims 39 to 41, characterized in that the compound for the control of molecular weight is the CoIII analogue of the chelate Coll, in which the atom Co is additionally bound, in a direction at right angles to the system of macrocyclic ring to H, to the halide or other anion, or a homologetically dissociable organic group.

43. The chelate Co according to any of claims 39 to 42, characterized in that the chelate Co has at least one other ligand which is coordinated to the Co atom, which does not alter the state of covalence.

44. The process for the production of the chelate Coll of the formula I, in which each B is F, which is characterized in that it comprises a) reacting a substituted benzyldioxy with benzene, which substitution corresponds to the desired substitution in the finished product, with cobalt acetate (preferably as tetraacetate) using diethyl ether as solvent and under an atmosphere of deoxygenated nitrogen making sure that the reaction temperature does not exceed 5 ° C, b) boronate borotrifluoride is introduced into the reaction mixture , making sure that the reaction temperature does not exceed 5 ° C, c) the reaction mixture is heated to 40 ° C and maintained at that temperature to ensure the reaction, d) the reaction temperature is cooled to 0 ° C, e) a base such as sodium carbonate is added, f) it is stirred for an additional period and then methanol is added, g) the product is isolated by filtration, washed with water, and then washed with methanol, to produce the chelate Co as the dimethanol complex. SUMMARY OF THE INVENTION A process for the polymerization of free radicals of olefinically unsaturated monomer or monomers, using a free radical initiator, the polymerization is carried out in the presence of a compound to effect molecular weight control, in which the compound for the control of molecular weight is a Coll chelate, of the formula (I) in which each group X, independently in each ring and in different rings, is a substituent selected from alkyl of 1 to 14 carbon atoms and cycloalkyl of 6 to 14 carbon atoms; n independently in each ring, is from 0 to 5 with the proviso that in at least one ring, n is from 1 to 5; Z independently on each boron atom, is selected from F, Cl, Br, OH, alkoxy of 1 to 12 carbon atoms, aryloxy of 6 to 12 carbon atoms, alkyl of 1 to 12 carbon atoms and aryl of 6 to 12 carbon atoms; or two Z groups taken together provides one or both boron atoms, a group -O- (Q) -O- where Q is a divalent aryl or a linking alicyclic group or an alkylene linking group, or two Z groups taken together on one or both boron atoms provide a 1,5-cyclooctanediyl bond group; or is a CoIII analogue of the chelate of Coll of the formula (I) in which the Co atom is covalently bonded additionally, in a direction at right angles to the ring system of the macrocyclic chelate to H, to the halide or other anion , or a homologetically dissociable organic group; and wherein optionally at least one other ligand is coordinated to the Coll or CoIII atom, being a ligand which does not alter the covalence state of Co. Also the Co chelates used in the polymerization process, a process for its production and the use in several applications of oligomers made using the polymerization process.