Process to make copolymers having polyamide blocks and polyether blocks
The present invention relates to a process for preparing, by condensation, copolymers having polyamide blocks and polyether blocks in which polyamide blocks having dicarboxylic chain ends are mixed with: a polyether having two OH chain ends (a polyetherdiol), and a polyol having at least 3 OH functions. The copolymers have a higher molecular weight, higher mechanical properties (impact, processing, filmification etc), remain linear or only weakly branched. The multifunctionality of the polyol is only used for kinetic aspects. As regards the process, there is a reduction of cycle time, reduced technical requirements on the catalyst and vacuum system and a reduction of degradation which means a better colour stability. The invention also relates to these copolymers having polyamide blocks and polyether blocks and comprising in its chain the residues of a polyol having at least 3 OH functions.
1 . A process for preparing by condensation, copolymers having polyamide blocks and polyether blocks comprising the step of admixing:
a) polyamide blocks having dicarboxylic chain ends;
b) a polyether having two OH chain ends (a polyetherdiol); and
c) a polyol having at least 3 OH functions, wherein said admixture optionally comprises a catalyst.
2 . The process according to claim 1 wherein the polyamide blocks having dicarboxylic chain ends are beforehand prepared by condensation of polyamide precursors in the presence of a chain-limiting dicarboxylic acid.
3 . The process according to claim 1 in which are admixed: polyamide precursors and a chain-limiting dicarboxylic acid; a polyether having two OH chain ends (a polyetherdiol); and a polyol having at least 3 OH functions, optionally in the presence of a catalyst.
4 . The process according to claim 1 , wherein the molecular weight of the polyol is lower than 1000.
5 . The process according to claim 4 wherein the molecular weight of the polyol is between 50 and 500.
6 . The process according to claim 5 wherein the polyol is pentaerythritol.
7 . The process according to claim 1 , wherein the polyol comprises between 0.01 and 5 percent of the weight of the copolymer.
8 . The process according to claim 7 wherein the polyol comprises between 0.1 and 1 percent of the weight of the copolymer.
9 . A copolymer having polyamide blocks and polyether blocks comprising in their chain the residues of a polyol having at least 3 OH functions.
10 . The copolymer according to claim 9 wherein the residues of said polyol are bound to the polyamide blocks through ester links.
11 . The copolymer according to claim 9 having a polydispersity index (Ip) between 2 and 3
12 . The copolymer according to claim 9 wherein the relative solution viscosity is above 1.
13 . The copolymer according to claim 9 wherein the relative solution viscosity is above 1.2.
14 . The copolymer according to claim 9 wherein the branching coefficient g′ (LCB) is >0.7.