Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1998-09-18
2000-03-21
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...
525329, 5263072, 5263076, C08F 832
Patent
active
060403861
DESCRIPTION:
BRIEF SUMMARY
Copolymers comprising from 68 to 95 mol % of sodium acrylate and from 32 to 5 mol % of lauryl acrylate are already known, from J. Applied Polymer Science, vol. 44, pp. 869-876 (1992), which are useful for the dispersion of polar and non-polar particles, such as titanium dioxide and carbon black. The dispersion of graphite particles by means of a copolymer, with an average molecular weight of 20,000, of maleic anhydride and of a-olefin having a so-called "comb" structure with simultaneously hydrophilic and hydrophobic side chains is also known from J. Dispersion Science and Technology, 13(2), pp. 195-200 (1992).
Patent E-P-B-107,403 describes a stable aqueous dispersion comprising a water-insoluble copolymer emulsion obtained from 10 to 70 weight % of (meth)acrylic acid, from 0.5 to 25 weight % of N-dodecylacrylamide and, preferably, at least 30 weight % of (C.sub.1 -C.sub.4)alkyl (meth)acrylate. After neutralization by an alkaline hydroxide or volatile amine, this emulsified copolymer becomes highly viscous and capable of thickening various aqueous media, such as water paints, pigmental dispersions, and the like.
U.S. Pat. No. 4,524,175 describes a stable water-in-oil emulsion comprising a non-continuous aqueous phase containing an associative hydrophobic copolymer obtained from 40 to 99.9 mol % of acrylamide, from 0 to 50 mol % of acrylic acid and from 0.1 to 10 mol % of (C.sub.8 -C.sub.12)alkyl (meth)acrylate, the said copolymer having a molecular weight of 800,000 to 2,500,000.
U.S. Pat. No. 4,432,881 describes the use, in a water-soluble thickening agent, of a copolymer of (meth)acrylic acid and of a water-insoluble monomer possessing a hydrophobic group containing at least 8 carbon atoms, such as an ethylenically unsaturated N-alkylamide. In this thickening agent, this copolymer is used in combination with a water-dispersible non-ionic surfactant in a ratio by weight of the copolymer to the surfactant of between 0.5 and 20.
Patent FR-A-2,693,202 describes, as thickening agents for aqueous saline solutions, water-soluble amphiphilic copolymers of sodium or potassium acrylate and of N-monoalkylacrylamide (the alkyl group being C.sub.8 -C.sub.16), the total number of monomer units being between 500 and 20,000 and the N-monoalkylacrylamide units, present in the proportion of 0.5 to 20 mol %, being distributed non-statistically along the chains, that is to say, on the whole, of the block type.
European Patent Application EP-A-0,494,022 describes a copolymer originating from the copolymerization of a mixture of monomers comprising at least 30% by weight of at least one organic carboxylic acid with ethylenic unsaturation; at least 30% by weight of at least one N-alkylacrylamide, the alkyl group of which contains from 8 to 30 carbon atoms in the alkyl chain; and from 0 to 40% of at least one hydrophilic unsaturated monomer, as well as a corresponding copolymer in which the carboxyl groups are completely or partially salified.
Although the majority of these documents have perceived the advantage of incorporating units derived from fatty N-alkylacrylamides in copolymers capable of influencing the viscosity of aqueous media, none of the copolymers described can be used industrially for the dispersion of pigments, in particular of hydrophobic pigments. This is probably due to inappropriate selection of the main parameters of the copolymers, in particular the choice of very high molecular weights and, in some cases, the presence of a third monomer, such as alkyl (meth)acrylate.
A first aim of the present invention is therefore to define (meth)acrylic copolymers which are easy to produce industrially and which can be used directly as pigment dispersants. A second aim of the present invention is to provide aqueous dispersions of pigments, in particular of hydrophobic pigments, which exhibit (in standard shear gradients, i.e. from 1 to 500 s.sup.-1) low viscosities, for example from approximately 0.01 to 5 Pa.s, even at low levels of use of the (meth)acrylic copolymer.
It has been found, surprisingly, that these obje
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Kuo, Ping-Lin, et al., Journal of Applied Polymer Science, vol. 44, pp. 869-876 (1992).
Zu, Qun, et al., J. Dispersion Science and Technology, 13(2), pp. 195-200 (1992).
ANS 14 of 22--AN 1994:458487 DN 121:58487 Meadows et al--Langmuir(1994), 10(7), 2471-9 Inhouse Computer Searched Abstract pp. 45-47.
Gillet Jean-Philippe
Iliopoulos Ilias
Lafuma Francoise
Pezron Erwoan
Cray Valley S.A
Lipman Bernard
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