Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1991-01-22
1994-05-10
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
528486, 528491, 528492, 525285, 525287, 525291, 525296, C08L 3326, C08J 300
Patent
active
053107748
DESCRIPTION:
BRIEF SUMMARY
This invention relates to water soluble and water swellable polymers of ethylenically unsaturated monomers and their stabilisation so as to reduce molecular weight degradation during storage and use. It also relates to polyacrylamides in which this problem of degradation is particularly significant.
When making a water soluble or swellable polymer from ethylenically unsaturated monomer, it is normal to try to achieve full polymerisation of the monomers but in reality some monomer always remain unpolymerised in the polymeric reaction product. This may be relatively unimportant in the case of some monomers but it is known to be undesirable in the case of methacrylamide or, especially, acrylamide because of the toxicity of this monomer. It is normal practice therefore to conduct acrylamide polymerisation so as to reduce the acrylamide content to as low a value as is conveniently possible, which in practice generally means that the polymer has a residual free acrylamide content of, typically, 0.2 to 0.5%.
Extensive studies have been made of the performance of polymers of ethylenically unsaturated monomers and it is known that they are liable to undergo degradation during storage or use. This degradation is particularly serious for the higher molecular weight polymers, for instance molecular weight above one million. The fact that degradation is occuring is manifested by, for instance, a reduction in the solution viscosity of the polymer. In those circumstances when the polymer is being used as a viscosifier the reduction in viscosity would probably be noticed, but even then this might be put down to other factors, for instance that the polymer as initially made had lower solution viscosity than was expected. Also, it may not be practical to measure solution viscosity during use (e.g. when the polymer is being used downhole). In other situations, e.g. as a flocculant, the solution viscosity of the polymer may not normally be measured and the performance of the polymer may depend upon a whole range of factors of which solution viscosity is only one, and so in theory performance could be put down to any of these factors and, again, may be attributed to inferior properties in the polymer as manufactured initially.
Even when it is observed that solution viscosity has been reduced this reduction could be due to changes in the side groups, for instance, hydrolysis, or could be due to cleavage of the backbone, i.e. reduction of molecular weight, and it can be relatively difficult to prove clearly which effect is occurring.
Despite these uncertainties as to the cause of degradation, there have been numerous proposals to incorporate various degradation inhibitors in polyacrylamides. Examples are given in the following Chemical Abstracts, namely isobutanol, trichlorphenolate and amino acids in volume 108 189657g, phosphonates in volume 106 511875f, N-methyl-2-pyrrolidone in volume 105 229619t, maleic anhydride acylation derivatives of urea, thiourea, phenylurea or ethanolamine in volume 99 140769b, various sulphur compounds such as thiocarbonates in volume 56 52294m, thiourea and polyethylene glycol in volume 91 23783g and various compounds such as napthoquinone in volume 98 108362g. Many of the additives are described as being added to prevent oxidation of the polymer and in Chemical Abstract 88 23892y an inorganic reducing agent is used.
In FR-A-2604444 the viscosity of a polyacrylamide for enchanced oil recovery is stabilised by adding at least 5% acrylamide monomer, base on the polymer. In JP-A-60/210657 it is proposed to stabilise polyacrylamide homopolymers, and copolymers of acrylamide with less than 50% of the monomers, that are to be used for purpose such as flocculation, paper-making, enhanced oil recovery, viscosifiers and soil improvers. This stabilisation is by the addition of at least 0.5% of a water soluble vinyl monomer and in the examples the monomers used are acrylamide (in an amount up to 7%) sodium acrylate, methacrylamide, acrylonitrile, dimethylaminoethyl acrylate and 2-acrylamido-2-methylpropane su
REFERENCES:
patent: 2649434 (1953-08-01), Coover et al.
patent: 2831841 (1958-04-01), Jones
patent: 3901857 (1991-08-01), Sackman et al.
patent: 4247405 (1981-01-01), Wier
patent: 4306048 (1981-12-01), Yoshida et al.
patent: 4559074 (1985-12-01), Clarke
patent: 4563290 (1986-01-01), Okada et al.
patent: 4687807 (1987-08-01), Wetegrove et al.
patent: 4778836 (1988-10-01), Farrar et al.
patent: 4906732 (1990-03-01), Farrar et al.
patent: 4929717 (1990-05-01), Chmelir
patent: 4996251 (1991-02-01), Farrar et al.
Allied Colloids Limited
Michl Paul R.
Szekely Peter
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