Process for controlling the pot life of polyurethane based systems, characterized in that - at least one carbodiimide of formula where m is 0 - 10, R 1, R 3 and R 5 are each independently H or methyl, R 2 and R 4 are each independently H, methyl, NH-C -OR 10, where R 10 is C 1 -C 4 -alkyl, or -(CH 2) h -O-[(CH 2) k -O] g -R 11, where h is 1-3, k is 1-3, g is 0-12 and R 11 is H or C 1 -C 4 -alkyl, and R 6, R 7, R 8 and R 9 are each independently H or methyl, and at least one diisocyanate and one diamine selected from the group of 2-methylpropyl 3,5-diamino-4-chlorobenzoate, bis(4,4'-amino-3-chlorophenyl)methane, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-diethyl-2,4-tolylenediamine, 3,5-diethyl-2,6-tolylenediamine, 4,4'-methylenebis(3-chloro-2,6-diethylaniline) and 1,3-propanediol bis(4-aminobenzoate) are stirred into - at least one polyol selected from the group of polyester polyols and/or polyetherester polyols and at temperatures in the range from 40 to 130°C. - at least one carbodiimide of formula where m is 0 - 10, R 1, R 3 and R 5 are each independently H or methyl, R 2 and R 4 are each independently H, methyl, NH-C -OR 10, where R 10 is C 1 -C 4 -alkyl, or -(CH 2) h -O-[(CH 2) k -O] g -R 11, where h is 1-3, k is 1-3, g is 0-12 and R 11 is H or C 1 -C 4 -alkyl, and R 6, R 7, R 8 and R 9 are each independently H or methyl, and at least one diisocyanate and one diamine selected from the group of 2-methylpropyl 3,5-diamino-4-chlorobenzoate, bis(4,4'-amino-3-chlorophenyl)methane, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-diethyl-2,4-tolylenediamine, 3,5-diethyl-2,6-tolylenediamine, 4,4'-methylenebis(3-chloro-2,6-diethylaniline) and 1,3-propanediol bis(4-aminobenzoate) are stirred into where m is 0 - 10, R 1, R 3 and R 5 are each independently H or methyl, R 2 and R 4 are each independently H, methyl, NH-C -OR 10, where R 10 is C 1 -C 4 -alkyl, or -(CH 2) h -O-[(CH 2) k -O] g -R 11, where h is 1-3, k is 1-3, g is 0-12 and R 11 is H or C 1 -C 4 -alkyl, and R 6, R 7, R 8 and R 9 are each independently H or methyl, and at least one diisocyanate and one diamine selected from the group of 2-methylpropyl 3,5-diamino-4-chlorobenzoate, bis(4,4'-amino-3-chlorophenyl)methane, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-diethyl-2,4-tolylenediamine, 3,5-diethyl-2,6-tolylenediamine, 4,4'-methylenebis(3-chloro-2,6-diethylaniline) and 1,3-propanediol bis(4-aminobenzoate) are stirred into where h is 1-3, k is 1-3, g is 0-12 and R 11 is H or C 1 -C 4 -alkyl, and R 6, R 7, R 8 and R 9 are each independently H or methyl, and at least one diisocyanate and one diamine selected from the group of 2-methylpropyl 3,5-diamino-4-chlorobenzoate, bis(4,4'-amino-3-chlorophenyl)methane, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-diethyl-2,4-tolylenediamine, 3,5-diethyl-2,6-tolylenediamine, 4,4'-methylenebis(3-chloro-2,6-diethylaniline) and 1,3-propanediol bis(4-aminobenzoate) are stirred into - at least one polyol selected from the group of polyester polyols and/or polyetherester polyols and at temperatures in the range from 40 to 130°C.