Process for preparing polyacrylates
View Patent ↗Process for preparing polyacrylates, by the free-radical polymerization of monomer mixtures comprising at least 70% by weight of at least one acrylic and/or methacrylic ester in the presence of amino acids as regulator substances, and reaction solution comprising one or more solvents and one or more monomers, at least 50% by weight of the solvents being organic solvents, and at least 70% by weight of the monomers being acrylic and/or methacrylic esters, with at least one amino acid being present.
1. Process for preparing a polyacrylate pressure-sensitive adhesive from a reaction solution consisting of a solvent selected from the group consisting of a single organic solvent or a mixture of two or more organic solvents, one or more monomers, at least 70% by weight of the monomers being acrylic and/or methacrylic esters, free radical initiator and one or more natural or non-natural α-amino acids of the following structural formula
where R 1 , R 2 and R 3 are selected independently of one another, with R 1 selected from the group (i), consisting of
(i) linear and branched C 1 to C 18 alkyl radicals, linear and branched C 2 to C 18 alkenyl radicals, linear and branched C 2 to C 18 alkynyl radicals, arylradicals, cycloaliphatic, aliphatic and aromatic heterocycles, and hydrogen,
and where one of R 2 or R 3 is hydrogen, and the other is selected from the group consisting of group (ii),
(ii) acyl radicals (—C(O)—R′), alkoxycarbonyl radicals (—C(O)—O—R′), carbamoyl radicals (—C(O)—NR′R″), and sulphonyl radicals (—SO 2 R′),
where R′ and R″ are radicals from group i) that are selected independently of one another,
and X is oxygen (O), sulphur (S) or selenium (Se),
and n is a natural number including zero
by free-radical polymerization, wherein the solvent is removed from the polymerization product after the polymerization, down to a residual solvent fraction of not more than 2% and wherein the amino acid or acids remain in the polymerization product when the solvent is removed.
2. Process according to claim 1 wherein the solvent removed is supplied to a recycling operation.
3. Process according to claim 1 , wherein at least one of the organic solvents used is taken from a recycling operation.
4. Process for the free-radical polymerization of monomer mixtures comprising at least 70% by weight of at least one acrylic and/or methacrylic ester, wherein amino acids are present as regulator substances.
5. Process according to claim 1 , wherein the reaction solution is a homogeneous solution.
6. Process according to claim 1 , wherein said at least one amino acid has at least one sulphanyl, selanyl and/or hydroxyl group.
7. Process according to claim 6 , wherein said at least one sulphanyl, selanyl and/or hydroxyl group is terminal.
8. Process according to claim 1 , wherein n is in the range 0≦n≦18.
9. Process according to claim 1 , wherein the acrylic and/or methacrylic ester or esters satisfy the formula
where
R 1 ═H or CH 3
and
R 2 ═H or an unbranched or branched, aliphatic, alicyclic or aromatic, unsubstituted or substituted hydrocarbon radical having 1 to 20 carbon atoms without C═C double bonds.