Process for the preparation of silylated polymers employing a backmixing step
View Patent ↗A continuous process for preparing a silylated polymer comprising a silylation step where a prepolymer having reactive functional groups, a first intermediate product, is reacted continuously with a silylating agent in an endcapping tubular reaction unit to form a second intermediate product, and where at least a portion of the second intermediate product is backmixed continuously with the first intermediate product to form the silylated polymer. The continuous process may further comprise a stabilization step, a quenching step or both a stabilization step and a quenching step.
1. A process for the preparation of a silylated polymer comprising
continuously reacting a prepolymer with a silylating agent, by a silylation reaction, to produce a silylated polymer composition; and
continuously backmixing at least a first portion of the silylated polymer composition with a loop connected from a downstream outlet to an upstream outlet of a reactor to adjust at least one upstream process parameter.
2. The process of claim 1 , wherein the silylated polymer composition comprises a fully silylated polymer and a partially silylated polymer.
3. The process of claim 1 , wherein a weight ratio of the first portion of the silylated polymer composition to the prepolymer ranges from about 0.05:1 to about 5:1.
4. The process of claim 1 , wherein the at least one upstream process parameter is at least one of residence time, temperature, weight ratio of the first portion to the prepolymer.
5. The process of claim 1 , wherein the prepolymer is a polyol with reactive functional groups or a chain extended prepolymer with reactive functional groups.
6. The process of claim 5 , wherein the reactive functional groups of either or both of the polyol and chain extended polymer are terminal reactive functional groups.
7. The process of claim 5 , wherein the chain extended prepolymer is prepared by continuously reacting a polyol with a chain extension agent.
8. The process of claim 1 further comprising continuously reacting at least a second portion of the silylated polymer composition with a scavenging agent or scavenging package to produce a quenched silylated polymer composition.
9. The process of claim 7 , wherein the chain extension agent is a diisocyanate or a polyisocyanate.
10. The process of claim 6 , wherein the terminal reactive functional groups are at least one of hydroxyl or isocyanate.
11. The process of claim 1 , wherein the silylating agent is an isocyanatosilane, mercaptosilane, hydroxyl-functional silane or an aminosilane.
12. The process of claim 1 , wherein the silylated polymer composition comprises a moisture-curable silylated polyurethane polymer.
13. The process of claim 8 , wherein the scavenging package comprises at least one cyclic amide scavenging agent.
14. The process of claim 13 , wherein the scavenging package further comprises a vinyltrimethoxysilane in a blend with the at least one cyclic amide scavenging agent.
15. The process of claim 13 , wherein the cyclic amide is selected from the group consisting of ε-caprolactam, 2-pyrrolidone and combinations thereof.
16. The process of claim 6 , wherein at least one of the terminal reactive functional groups is isocyanate and the silylating agent is an aminosilane.
17. The process of claim 6 , wherein at least one of the terminal reactive functional groups is a hydroxyl group and the silylating agent is an isocyanatosilane.
18. The process of claim 1 , further comprising adding a stabilization package to the process.
19. The process of claim 18 , wherein the stabilization package comprises at least one of a hindered phenol or phosphite stabilizer.
20. The process of claim 14 further comprising a stabilization package having triisodecyl phosphite.