Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-05-02
2004-11-30
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S077000, C526S078000, C526S080000, C526S201000, C526S220000, C526S193000, C526S922000, C526S219000, C526S227000, C526S319000, C526S327000, C525S259000, C525S314000
Reexamination Certificate
active
06825290
ABSTRACT:
A subject-matter of the present invention is a process for the preparation of latices using block copolymers as surfactants and the latex compositions prepared by the said process.
The invention likewise relates to the preparation of latices exhibiting high resistance to water and which can be used in particular as concrete or cement additive in formulations intended for applications in particular in building materials, adhesives, paints or papers.
Latices are products which are well known to a person skilled in the art, as well as the redispersible powders obtained from these latices. They have numerous applications, in particular as additives in paint formulations or paper formulations (coating slips, bulk paper) or in formulations intended to be applied in the construction field (adhesive, pastes, smoothing coats, and the like). They confer important properties on the formulas in the composition of which they participate, by virtue, for example, of their binding capability, of their film-forming capability and of their ability to confer specific rheological properties.
Generally, for all latex applications, the aim is to reconcile good colloidal stability of the aqueous formulas before drying and good resistance to water after drying.
Processes for the preparation of latices have been well known for many years. It is also known to add a surfactant of low molecular weight to the aqueous phase, so as to keep in suspension both the monomers and the polymers in small spheres in suspension in the water, within which spheres the radical polymerization reaction takes place. However, this addition of surfactant has the disadvantage of allowing surfactant residues to remain on the latex particles, which can be harmful to the properties of the compositions comprising the said latices.
One of the aims of the present invention is to provide a process for the preparation of latices which makes it possible to solve the abovementioned problems.
These aims and others are achieved by the present invention, a subject-matter of which is thus a process for the preparation of latices by radical aqueous emulsion polymerization in the presence:
of at least one ethylenically unsaturated monomer,
of at least one radical polymerization initiator, and
of at least one surface-active block copolymer comprising at least one hydrophilic block and at least one hydrophobic block which is prepared by a “living” preparation process using a transfer agent, the said copolymer exhibiting:
a number-average molecular mass of between 2 000 and 20 000, preferably between 4 000 and 16 000,
a glass transition temperature of the hydrophobic block of less than 30° C., preferably of less than 25° C., and greater than −100C.,
a surface tension of less than 60 millinewtons per metre (mN/m), preferably of less than 50 mN/m, measured at a concentration in demineralized water of less than or equal to 10
−4
mol/l at 20° C. and under one atmosphere, and
the transfer agent having been rendered inert with respect to the said radical polymerization.
The invention also relates to formulations which are intended to be applied in the field of building materials, in that of paints, in that of papers and in that of adhesives and pressure-sensitive adhesives and which comprise the latices prepared by the said process or the redispersible powders capable of being obtained by drying the latices.
It likewise relates to the use of the latices and redispersible powders in formulations intended to be used in particular in the construction field or in the field of paints.
However, other advantages and characteristics of the present invention will become more clearly apparent on reading the description and examples which will follow.
According to the invention, surface-active block copolymers comprising at least one hydrophilic block and at least one hydrophobic block are prepared by a “living” or “controlled” radical polymerization process involving the use of a transfer agent specifically for the purpose of controlling the said radical polymerization. The hydrophilic block preferably derives from hydrophilic monomers, and the hydrophobic block preferably derives from hydrophobic monomers.
Generally, the preceding block copolymers can be obtained by any “living” or “controlled” polymerization process, such as, for example:
radical polymerization controlled by xanthates according to the teaching of Application WO 98/58974,
radical polymerization controlled by dithioesters according to the teaching of Application WO 98/01478,
polymerization using nitroxide precursors according to the teaching of Application WO 99/03894,
radical polymerization controlled by dithiocarbamates according to the teaching of Application WO 99/31144,
atom transfer radical polymerization (ATRP) according to the teaching of Application WO 96/30421,
radical polymerization controlled by iniferters according to the teaching of Otu et al., Makromol. Chem. Rapid. Commun., 3, 127 (1982),
radical polymerization controlled by degenerative transfer of iodine according to the teaching of Tatemoto et al., Jap. 50, 127, 991 (1975), Daikin Kogyo Co Ltd Japan, and Matyjaszewski et al., Macromolecules, 28, 2093 (1995),
group transfer polymerization according to the teaching of Webster O. W., “Group Transfer Polymerization”, p. 580-588, in the “Encyclopedia of Polymer Science and Engineering”, Vol. 7, edited by H. F. Mark, N. M. Bikales, C. G. Overberger and G. Menges, Wiley Interscience, New York, 1987,
radical polymerization controlled by tetraphenylethane derivatives (D. Braun et al., Macromol. Symp., 111, 63 (1996)),
radical polymerization controlled by organocobalt complexes (Wayland et al., J. Am. Chem. Soc., 116, 7973 (1994)).
The preferred transfer agents for implementing the controlled polymerization process are chosen from dithioesters, thioethers-thiones, dithiocarbamates and xanthates.
The preferred polymerization is the living radical polymerization using xanthates.
The invention additionally relates to a process for the preparation of these block polymers. This process consists in:
1—bringing into contact:
at least one ethylenically unsaturated monomer,
at least one source of free radicals, and
at least one transfer agent of formula (I):
in which:
R represents an R2O- , R2R′2N- or R3- group with:
R2 and R′2, which are identical or different, representing (i) an alkyl, acyl, aryl, alkene or alkyne group or (ii) an optionally aromatic, saturated or unsaturated carbonaceous ring or (iii) a saturated or unsaturated heterocycle, it being possible for these groups and rings (i), (ii) and (iii) to be substituted, R3 representing H, Cl, an alkyl, aryl, alkene or alkyne group, an optionally substituted, saturated or unsaturated (hetero)cycle, an alkylthio, alkoxycarbonyl, aryloxycarbonyl, carboxyl, acyloxy, carbamoyl, cyano, dialkyl- or diarylphosphonato, or dialkyl- or diarylphosphinato group, or a polymer chain,
R1 represents (i) an optionally substituted alkyl, acyl, aryl, alkene or alkyne group or (ii) a carbonaceous ring which is saturated or unsaturated and which is optionally substituted or aromatic or (iii) an optionally substituted, saturated or unsaturated heterocycle or a polymer chain, and
2—repeating, at least once, the above operation of bringing into contact using:
different monomers from the preceding implementation, and
instead of the precursor compound of formula (I), the polymer resulting from the preceding implementation, and
3—rendering the transfer agent inert at the end of the polymerization.
The R1, R2, R′2 and R3 groups can be substituted by substituted phenyl or alkyl groups, substituted aromatic groups or the following groups: oxo, alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl (—COOH), acyloxy (—O
2
CR), carbamoyl (—CONR
2
), cyano (—CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, isocyanato, phthalimido, maleimido, succinimido, amidino, guanidino, hydroxyl (—OH), amino (—NR
2
), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl or silyl, groups exhibiting a hydrophilic or ionic nature, suc
Adam Herve
Liu Wan-Li
Rhodia Inc.
Zalukaeva Tatyana
LandOfFree
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