Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1998-04-03
2001-05-22
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S225000, C526S292500, C526S344000
Reexamination Certificate
active
06235857
ABSTRACT:
The invention relates to processes for the production of polymers, including block, graft, homo and copolymers, of controlled molecular weight by free radical-initiated polymerization of unsaturated species in the presence of unsaturated halogen or sulfonyl-containing compounds, and such polymers with halogen or sulfonyl-containing end-groups produced by such processes. The polymers produced may also have olefinic end-groups. The invention also relates to novel graft copolymers formed using the polymers from this process, and block copolymers produced by this process.
In polymerization processes, it is necessary to be able to control the molecular weight of the polymer so that the product may be fitted to a particular use or need. For example, when an uncontrolled polymerization tends to produce very high molecular weight polymers, it may be necessary to limit the molecular weight and this must be done in a predictable and controllable fashion. In addition, polymers of limited molecular weight are particularly useful as precursors in the manufacture of other polymeric materials and as additives or components of formulations for plastics, elastomers and surface coating compositions, as well as being useful in their own right in many applications.
In conventional free radical-initiated polymerization, there are a number of ways of molecular weight reduction leading to a solution to the above problems. The most common method involves the use of additional initiator which acts as a free radical source or the use of the normal quantity of initiator in conjunction with a chain transfer agent (hereinafter referred to as “CTA”). If a CTA is used at least a part of this agent is incorporated into the polymer molecule. Ideally, molecular weight control must be achieved in such a way as to not introduce undesirable functionality into the polymer.
Although the use of CTAs offers a means of effecting molecular weight control, those in current use have a number of disadvantages. For example, the CTAs used in conventional free radical-initiated polymerization processes are alkanethiols which possess an objectionable odour and can lead to a wide distribution of molecular weights in batch polymerizations with certain monomers. Additionally, the use of thiols causes the incorporation of a sulphur atom into the polymer chain which can result in premature discoloration of the polymer, which is especially deleterious in the coatings industry. Furthermore, there is little scope with thiols for the chain transfer constant to be optimized for some particular vinyl polymerizations. Carbon tetrachloride which is frequently used in the polymer industry as a CTA is falling into disuse because it is toxic and an ozone depleting substance.
Existing addition/fragmentation transfer agents such as substituted vinyl ethers and allyl sulphides assist in overcoming many of the disadvantages of thiols and allow the installation of a number of different types of functional groups at the end of polymer molecules. However, these agents may have inappropriate chain transfer constants and/or give significant retardation of polymerisation with methyl acrylate, vinyl acetate and vinyl halides.
Olefinic end-functional polymers (often called “macromonomers” or “macromers”) are important as building-blocks for block and graft copolymers and polymer networks. Homo- and co-polymers of such macromers give rise to comb-type polymers with structures like those normally obtained by graft polymerization. Such homo- and co-polymers of macromers are useful inter alia as suspending/dispersing agents, compatibilisers or surfactants.
Several chloroallyl transfer agents for use in vinyl acetate polymerization have been described e.g. allyl chloride, methallyl chloride, 3-chloro-3-methylbut-1-ene and 1-chloro-3-methylbut-2-ene. These compounds differ from those of the present invention in that they do not possess a substituent Y=halogen and they are described as giving significant retardation. The transfer agents described in the present invention also have transfer constants appropriate for use with vinyl acetate, vinyl chloride and methyl acrylate polymerization.
According to one aspect of the present invention there is provided a process for the production of lower molecular weight polymers by free radical-initiated polymerization of unsaturated species characterized by the use of an unsaturated compound of Formula I as a chain transfer agent:
wherein R
1
and R
2
are the same or different and are selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted saturated, unsaturated or aromatic carbocyclic or heterocyclic ring and halogen;
X is selected from the group consisting of chlorine, bromine, optionally substituted alkylsulfonyl, and optionally substituted arylsulfonyl,
Y is selected from the group consisting of halogen, a polymer chain and CR
3
R
4
Z, wherein R
3
and R
4
are the same or different and are selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted saturated or aromatic carbocyclic or heterocyclic ring, and halogen; and
Z is selected from the group consisting of chlorine, bromine, optionally substituted alkylsulfonyl and optionally substituted arylsulfonyl;
provided that when X is optionally substituted alkylsulfonyl or optionally substituted arylsulfonyl, Y is not halogen.
In a preferred embodiment R
1
and R
2
are selected from hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, phenyl, biphenyl, naphthyl, chlorine and fluorine. More preferably R
1
and R
2
are selected from hydrogen, methyl, phenyl, chlorine and fluorine. Most preferably R
1
and R
2
are both hydrogen.
Suitable alkylsulfonyl and arylsulfonyl include p-toluenesulfonyl (“tosyl”), methanesulfonyl (“mesyl”), trifluoromethanesulfonyl and benzenesulfonyl.
In a further preferred embodiment when Y is CR
3
R
4
Z, R
3
and R
4
are selected from hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, phenyl, biphenyl, naphthyl, tosyl, mesyl, trifluoromethanesulfonyl, benzenesulfonyl, chlorine and fluorine. More preferably R
3
and R
4
are selected from hydrogen, methyl, phenyl, tosyl, mesyl, chlorine and fluorine. Most preferably R
3
and R
4
are both hydrogen.
According to another aspect of the present invention there is provided the use of an unsaturated compound of general Formula I as a chain transfer agent in a process for the production of lower molecular weight polymers by free radical-initiated polymerization of an unsaturated species.
The term “optionally substituted” as used herein means that a group may or may not be substituted with one or more substituents which do not interfere with or participate in the polymerization process. Examples of such substituents include alkyl, aryl, hydroxyalkyl, aminoalkyl, carboxylic acid, ester, acyloxy, amide, nitrile, haloalkyl, alkoxy, phosphonate, sulfonate, silyl or silyloxy group. When used in relation to a moiety containing a ring, the term “optionally substituted” further means that the moiety may or may not have substituent groups directly or indirectly attached to the ring by means of a methylene group or other side chain. Any such substituent groups do not take part in the actual lowering of the molecular weight but may be capable of subsequent chemical reaction. If the substituent is capable of subsequent reaction, the lower molecular weight polymer containing such reactive substituent group is thereby able to undergo further chemical transformation, such as being joined with another polymer chain. Suitable reactive substituents includes hydroxy, amino, halogen, allyl, cyano, epoxy, carboxylic acid and its derivatives, such as esters and the like.
The optionally substituted alkyl groups may contain up to 32 carbon atoms and be straight chained or branched. Examples of straight chained and branched alkyl include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, amyl, isoamyl, sec-amyl, 1,2-dimethylpropyl, 1,1-dimethylp
Chong Yen Kwong
Moad Graeme
Rizzardo Ezio
Thang San Hoa
Bacon & Thomas
Commonwealth Scientific and Industrial Research Organisation
Dawson Robert
Robertson Jeffrey B.
LandOfFree
Control of molecular weight and end-group functionality in... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control of molecular weight and end-group functionality in..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control of molecular weight and end-group functionality in... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2503961