Patent GB-1382933-A (GB)
Title: Microcapsules
IPC: B01J13/02
Filed: 1973-02-15
Abstract: 1382933 Coated microcapsules; dialysis RHONE-POLLENC SA 15 Feb 1973 [16 Feb 1972] 7587/73 Headings B1X and B2E Substantially spherical microcapsules of diameter 10Á to 5mm, suitable for the dialytic removal of urea from solution e.g. in connection with dialytic or ultrafiltration kidney machines, consist essentially of a cross-linked polymer containing sulphonic acid groups and possessing a theoretical exchange capacity greater than 0.5 meq/g or dry polymer, have a skin coating of a polymer containing quaternary ammonium groups bonded by at least one covalent bond to the chain of the polymer, the polymer possessing a permeation selectivity greater than 55% and a water absorption of between 2 and 50%, the thickness of the skin being 0.1 to 20% of the radius of the microcapsule. The sulphonic acid group-containing polymers may contain (a) 50-90% of the formula:  (b) 2-50% of units of the formula:  and (c) 0-30% units of formula: in which each of the R 1  radicals, which may be the same or different, is a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms, R is either a valency bond or a linear or branched, unsubstituted or substituted by one or more halogen atoms or OH groups, alkylene or alkenylene radical containing at most 6 carbon atoms, a phenylene radical or a divalent radical consisting of either alkylene radicals linked by -O-O-S-atoms or of at least one alkylene radical and at least one phenylene radical linked together either directly or via -O-O-S-atoms, the total number of carbon atoms in the alkylene group of the said divalent radicals being at most 18, the divalent radicals containing at most 3 phenylene radicals, or a -O-R'-O-S-R'- group, R' representing a divalent radical as defined above for R, each of the R 2  radicals being hydrogen, halogen or an alkyl radical containing 1 to 4 carbon atoms, each of the R 3  radicals being as R 2  or a radical of formula:  where R 4  represents a halogen atom or a linear or branched alkyl radical containing up to 30 carbon atoms, a cycloalkyl radical of 5 or 6 carbon atoms in the ring or an aryl, alkoxyaryl or aralkoxy radical, the symbol -Z- represents a divalent atom or group which is -O-, -S-, -NH-, -SO 2 - or a divalent organic radicalwhich may optionally contain -SO 3 H substituent and X represents a -SO 3 H group in at least a part of the units of formula (I) and in the remaining units of formula (I) (if any) a hydrogen atom. The sulphonic acid group containing polymers may be obtained by polymerization of monomers containing sulphonic acid group constituents or by sulphonation of a preformed polymer. Numerous suitable Examples are given. The polymer forming the skin may the reaction product of (a), a polymer comprising a plurality of units of the formula: either alone or with up to 90% of units of formula (III), and R 5  representing (1) a group of the formula: n being 1 to 4, each of the R 6  radicals being an alkyl radical with 1 to 6 carbon atoms and -R 7 - being a linear or branched alkylene radical with up to 12 carbon atoms or a cycloalkylene radical with 5 or 6 ring carbon atoms, or a phenylene radical, or (2) a heterocyclic radical with 5 or 6 ring members, containing 1 or 2 nitrogen atoms but no other hetero-atom, optionally fused to 1 or 2 benzene rings, the atom or at least one of the nitrogen atoms of the heterocyclic radical being bonded by its free valencies to adjacent carbon atoms in the heterocyclic ring being bonded by 2 valencies to said carbon atom and by the third to a group R 6 , with (b) a monoquaternizing and/or polyquaternizing compound. The polymer of the skin may also be formed by function of a polycondensate comprising a plurality of units of the formula:  in which Q is a divalent organic radical capable of forming a diacid of the formula HOOC-Q-COOH, T 1  is a divalent organic radical capable of forming a dial of formula OH-T 1 -OH, T 2  is a divalent organic radical capable of forming a diamine of the formula H 2 N-T 2 -NH 2 , at least one of the radicals represented by the symbols Q and T 1  or T 2  containing a tertiary nitrogen atom with a mono- or poly-quaternizing agent. Alternately, the skin polymer may be the reaction product of a polymer comprising a plurality of units of the formula:  in which # represents an organic radical carying a halogen substituent in each of the E radicals represents a -O-, -SO 2 - or -(CH 2 ) v - group, v being 1 to 4 and, optionally, units which do not carry halogen atoms, with a tertiary monoamine or a compound carrying several tertiary minor groups. Numerous suitable compounds are listed. The microcapsules are obtained by coating microspheres of a sulphonic acid polymer with a solution of (a) a non-cross-linked cationic polymer in an organic solvent, which can be used directly, (b) with a solution of a cationic polymer possessing groups which make cross-linking possible and a cross-linking agent, or (c) a solution of a non-quaternized or partially quaternized, but not cross-linked, polymer which can, in addition, carry the active groups which make non-quaternizing possible with a poly-functional agent and a polyfunctional reagent ensuring cross-linking quaternization, optionally combined with a polyfunctional agent ensuring non-quaternizing cross-linking. A preferred method of applying the solution is from a fluidized bed of the sulphonic acid.