Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1993-07-28
1994-06-14
Lipman, Bernard
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
5253317, 5253321, 5253328, 5253338, 525383, 525388, C08F 806
Patent
active
053210948
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the manufacture of modified olefin polymers, in particular modified polypropylene polymers.
Polyolefins are a well known class of thermoplastic polymers of moderate strength and toughness (as compared with modern so-called "engineering polymers") and good chemical resistance; their relative inertness arising largely from their near paraffinic structures. Often this inertness is an asset, for example in piping for gas, water etc., or when used in lining chemical reactors, but for some uses it can be a disadvantage. Thus, it is difficult to cross link the polymers to increase strength, stiffness and temperature resistance, in a controlled manner, or to modify the polymer surface to make it more receptive or reactive to dyestuffs.
One way of making such polymers more reactive so that cross-linking or surface modification can be carried out in a controlled manner is to copolymerise into the polymer a monomer that provides a site for subsequent reaction. A significant part of this line of development has been by way of the synthesis of polyolefins, particularly polypropylene, using commonomers that introduce unsaturation into the molecule, usually in side chains. Examples of syntheses that follow this approach include those described in U.S. Pat. No. 4,606,077, European Published Applications Nos. 01710285 A and 0311299 A, PCT Application No. 90-12818 A, Japanese published Applications Nos. 02-051512 A and 02-145611 A and the article by G. Gechin and T. Simonazzi in Macromolecular Preprints 1989.
The unsaturation in the polymer can be used as a site for further reaction, and, if it is the side chain that is unsaturated, or if the unsaturation is only at the end(s) of the polymer chain, the further reaction is unlikely to result in cleavage of the main chain. Cleavage, would reduce the molecular weight in an uncontrolled manner with a corresponding adverse effect on the physical, especially mechanical, properties of the polymer. However, the relatively insert nature of olefin polymers makes such farther reaction awkward to carry out. Usually, in prior proposals, the polymer is dissolved, reacted in solution and the product subsequently isolated by evaporating the solvent. Typically toluene or other similar potent solvent has been used, if necessary, at elevated temperature to ensure solution of the polymer. Such methods are satisfactory in small scale laboratory preparations but are not suitable for large scale manufacture. The present invention adopts a different approach to the further reaction in that the reaction with the unsaturated polymer is carried out in a liquid medium which is compatible with but not a solvent for the polymer (or the modified polymer product). This makes separation of the liquid medium from the reaction product much easier and more straight forward than when solvents are used.
Accordingly the present invention provides a method of making a chemically modified olefin polymer which comprises dispersing solid particles of an ethylenically unsaturated olefin polymer in a liquid medium which is a compatible non-solvent for the unsaturated polymer; reacting the unsaturated polymer with an oxy-addition agent, particularly one which does not leave significant reactive residues and especially an epoxidising agent, in the liquid medium; and recovering the chemically modified polymer.
The polymers used as starting materials in this invention are unsaturated polyolefins. As the unsaturation is used to introduce functionality into the polymer rather than being itself the source of desired properties (as in diene rubbers) the bulk of the units in the unsaturated polyolefin are derived from mono-olefins which are usually alpha-olefins typically having from 2 to 10 carbon atoms. Where the predominant alpha-olefin units are derived from monomers other than ethylene, the polymer is desirably substantially isotactic. Isotactic olefin polymers are typically thermoplastic and this invention is particularly directed to the production of chemically modified thermo-plastic olefin po
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Imperial Chemical Industries plc
Lipman Bernard
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