PIPA Polyol Based Viscoelastic Foams

Patent metadata

Field	Value
Publication number	US-2016200855-A1
Application number	US-201414911721-A
Country	US
Kind code	A1
Filing date	Sep 11, 2014
Priority date	Sep 13, 2013
Publication date	Jul 14, 2016
Grant date	—

Abstract

Viscoelastic foam is made by reacting an isocyanate compound with water and a polyol mixture. The polyol mixture contains a dispersion of polyurethane or polyurethane-urea particles in a carrier polyol (a PIPA polyol) and at least one other polyol that is a homopolymer of propylene oxide or a copolymer of 20 to 99.9 weight-% propylene oxide and 0.1 to 80 weight-% ethylene oxide, has 2 to 4 hydroxyl groups per molecule and has a hydroxyl equivalent weight of 200 to 400. The VE foams are characterized by high airflows and long recovery times.

First claim

1 . A method of making a viscoelastic foam, comprising combining at least one organic polyisocyanate with water and a polyol mixture at an isocyanate index of 60 to 150 to form a reaction mixture and curing the reaction mixture to form a polyurethane-urea foam having a foam density of 30 to 120 kg/m 3 , a resiliency of less than 15% and a recovery time of at least 3 seconds, wherein the polyol mixture includes:
Polyol A: at least one dispersion of polyurethane and/or polyurethane-urea particles in a carrier polyol, wherein the carrier polyol has an average molecular weight of 600 to 5000 and an average of at least two hydroxyl groups per molecule, the dispersed polyurethane or polyurethane-urea particles constitute from 5 to 50 weight percent of the dispersion and the dispersion has a hydroxyl number of at least 40; and Polyol B: at least one polyol which is a homopolymer of propylene oxide or a copolymer of 20 to 99.9 weight-% propylene oxide and 0.1 to 80 weight-% ethylene oxide, has 2 to 4 hydroxyl groups per molecule and has a hydroxyl equivalent weight of 200 to 400; and further wherein Polyols A and B together constitute at least 75 weight-percent of all isocyanate-reactive materials other than water in the reaction mixture and the polyol mixture contains at least 1 weight-percent of the dispersed polyurethane or polyurethane-urea particles.

2 .. The method of claim 1 wherein the polyol mixture contains at least 1 weight-percent of the dispersed polyurethane or polyurethane-urea particles.

3 . The method of claim 2 wherein Polyol A constitutes 3 to 60 weight percent of the polyol mixture.

4 . The method of claim 3 wherein Polyol B constitutes 40 to 85 weight percent of the polyol mixture.

5 . The method of claim 1 wherein Polyol B is a mixture of Polyols B1 and B2, wherein Polyol B1 is at least one polyol which is a copolymer of 50 to 80 weight-% ethylene oxide and correspondingly 50 to 20 weight-% propylene oxide, has 2.5 to 3.5 hydroxyl groups per molecule and a hydroxyl equivalent weight of 200 to 400 and polyol B2 is at least one polyol which is a homopolymer of propylene oxide or a copolymer of greater than 80 weight-% propylene oxide and less than 20 weight-% ethylene oxide, has 2-4 hydroxyl groups per molecule and has a hydroxyl equivalent weight of 200 to 400.

6 . The method of claim 5 wherein Polyol B-1 constitutes 30 to 60 weight-% of the polyol mixture and Polyol B-2 constitutes 10 to 25 weight-% of the polyol mixture.

7 . The method of claim 1 , wherein Polyol A has a higher hydroxyl number than the carrier polyol.

8 . The method of claim 1 , wherein the dispersed polyurethane or polyurethane-urea particles constitute from 5 to 25 weight percent of Polyol A.

9 . The method of claim 1 , wherein Polyol A is a dispersion of 10 to 25% by weight dispersed polyurethane or polyurethane-urea particles in the carrier polyol(s), and the carrier polyol(s) have an average hydroxyl equivalent weight of 200 to 400, nominally contain 2 to 4, hydroxyl groups/molecule and contain at least 75% secondary hydroxyl groups.

10 . The method of claim 1 , wherein Polyol A is a dispersion of 10 to 25% by weight dispersed polyurethane or polyurethane-urea particles in the carrier polyol(s), and the carrier polyol(s) have an average hydroxyl equivalent weight of 401 to 1200, nominally contain 2 to 4 hydroxyl groups/molecule and contain at least 75% secondary hydroxyl groups.

11 . The method of claim 1 , wherein Polyol A is a dispersion of 10 to 25% by weight dispersed polyurethane or polyurethane-urea particles in the carrier polyol(s), and the carrier polyol(s) have an average hydroxyl equivalent weight of 1000 to 2500, nominally contain 2 to 4 hydroxyl groups/molecule.

12 . The method of claim 4 wherein the dispersed polymer particles are a reaction product of triethanolamine, toluene diisocyanate and optionally water.

13 . The method of claim 4 wherein the reaction mixture does not contain an SAN-type polymer polyol.

14 . The method of claim 13 wherein the polyol mixture contains no more than 2 weight-% of castor oil.

15 . (canceled)

16 . The method of claim 1 wherein the VE foam is made in a free-rise process wherein the curing step is performed by pouring the reaction mixture into an open container such that expansion in at least one direction occurs against the atmosphere or a lightweight surface that provides negligible resistance to the expansion of the foam.

17 . The method of claim 16 which is performed by continuously pouring the reaction mixture into the open container.

18 . The method of claim 1 wherein the VE foam is cured in a mold.

19 . The method of claim 1 wherein the VE foam has an airflow prior to crushing of at least 57 L/m and a recovery time of at least 3 seconds.

20 . The method of claim 1 wherein the VE foam has an airflow prior to crushing of at least 57 L/m and a recovery time of at least 10 seconds.

21 . The method of claim 1 wherein the VE foam has an airflow prior to crushing of at least 80 L/m and a recovery time of at least 10 seconds.

Assignees

• Dow Global Technologies Llc

Inventors

• Casati Francois
• Lora Lamia Alberto
• Hunter Dale
• Amici-Kroutilova Irena
• Cookson Paul A
• Delk Van M

Classifications

• C08G18/4883

  containing cyclic groups having at least one oxygen atom in the ring · CPC title

• C08G18/7621

  being toluene diisocyanate including isomer mixtures · CPC title

• C08G18/4009

  Two or more macromolecular compounds not provided for in one single group of groups C08G18/42 - C08G18/64 · CPC title

• C08G18/7671

  containing only one alkylene bisphenyl group · CPC title

• C08G18/7664 Primary

  containing alkylene polyphenyl groups · CPC title