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
1997-04-04
2000-09-12
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...
524560, 526305, 5263076, 5263184, 52631844, C08L 3900
Patent
active
061179353
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to solvent-soluble polymers, their preparation and their use as a rheology modifier (hereinafter RM) in non-aqueous pigment formulations.
Pigment formulations especially heat-treated paints for use in the coating industry having lower Volatile Organic Compound (VOC) content (e.g. reduced organic solvent) have become more popular. Such formulations have a high solids and lower solvent content and in order to maintain acceptable viscosity during application it is normal to use lower MW resins as film-forming binders in the formulation. However, because of the lower solvent content of these formulations, the viscosity increase associated with evaporation of the solvent on drying is less than that of conventional formulations which contain high MW resins and more solvent. This lower increase in viscosity results in a tendency of the coating to sag especially when applied to a vertical or near-vertical surface.
GB 2,269,178 discloses water-soluble amphiphilic polymers derived from polyacrylic acid which contain up to 20% molar ratio of acrylamide residues for use as thickeners in aqueous saline media.
It has now been found that a novel class of esters and amides of polyacrylic acid containing at least 30% molar ratio of amide and/or ester residues can be incorporated into pigment formulations as a RM and that they reduce the propensity of the coating to sag without impairing the film forming characteristics of the coating or causing an unacceptable increase in viscosity of the formulation at high shear. These esters and amides also act as stabilisers and reduce the tendency of any particulate solid dispersed in the formulation to sediment or layer, especially on storage.
According to the invention there is provided a polymer which is a polyacrylic acid or a poly(C.sub.1-4 -alkyl) acrylic acid wherein at least 30% of the --COOH groups are converted to --COY groups (hereinafter the "Polymer"); wherein
R.sup.2 and R.sup.3 is each, independently, hydrogen, alkyl or cycloalkyl; or
R.sup.2 and R.sup.3 together with the nitrogen atom to which they are attached form a ring provided that the total number of carbon atoms represented by R.sup.2 and R.sup.3 is from 4 to 18.
Preferably, the total number of carbon atoms in R.sup.1 or in R.sup.2 combined with R.sup.3 is not greater than 14, more preferably not greater than 12 and especially not greater than 10. The total number of carbon atoms in R.sup.1 or in R.sup.2 combined with R.sup.3 is at least 6.
Where R.sup.1, R.sup.2 or R.sup.3 is alkyl, it can be linear or branched but it is preferably linear. Examples are n-hexyl, iso-hexyl, n-octyl, 2-ethylhexyl, 3,7-dimethyloctyl, n-nonyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl and n-octadecyl.
Since some alcohols of formula R.sup.1 --OH and amines of formula NHR.sup.2 R.sup.3 which are used to make the Polymer are available commercially as mixed isomers or contain mixed alkyl chains, it is to be understood that each of R.sup.1, R.sup.2 and R.sup.3 may represent a mixture of different alkyl groups.
When R.sup.1, R.sup.2 or R.sup.3 is cycloalkyl, it preferably contains up to 6 carbon atoms and is especially cyclohexyl.
When R.sup.2 and R.sup.3 together with the nitrogen atom to which they are attached to form a ring it is preferably 6-membered. Examples are morpholino, piperidino, piperazino, and N-alkylpiperazino.
It is also preferred that Y is --OR.sup.1.
According to one aspect of the invention there is provided a polymer of formula 1 ##STR1## wherein
each, independently, of the n groups represented by R is H or C.sub.1-4 -alkyl;
each, independently, of the n groups represented by Y is --OH, --OR.sup.1 or --NR.sup.2 R.sup.3, and
n is from 200 to 25,000;
provided that the percentage of groups in which Y is other than --OH is greater than 30% of the total number of groups represented by Y.
The different monomer units having the side chains --COOH, --COOR.sup.1 and --CONR.sup.2 R.sup.3 may be randomly spaced along the polymer backbone or they may be present as blocks of the same monomer.
Prefe
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Gough Paul
Schofield John David
Michl Paul R.
Zeneca Limited
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