Viscoelastic flexible foams comprising hydroxyl-terminated prepolymers

Patent metadata

Field	Value
Publication number	US-10793692-B2
Application number	US-201816169323-A
Country	US
Kind code	B2
Filing date	Oct 24, 2018
Priority date	Oct 24, 2018
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

This invention relates to a process for preparing viscoelastic flexible polyurethane foam comprising reacting an isocyanate component with an isocyanate-reactive component that comprises a polyol blend having a hydroxyl number of 56 to 250 and an average functionality of greater than 2, and a hydroxyl-terminated prepolymer. The invention also relates to viscoelastic flexible polyurethane foams.

First claim

What is claimed is:

1. A process for preparing a viscoelastic flexible polyurethane foam comprising reacting:
(1) a diisocyanate and/or a polyisocyanate component,
with
(2) an isocyanate-reactive component comprising:
(a) from 20 to 100% by weight, based on 100% by weight of components (2)(a) and (2)(b), of a polyol blend having a hydroxyl number of from 56 mg KOH/g polyol to about 250 mg KOH/g polyol, an average functionality of greater than 2, and comprising:
(i) a monofunctional polyether having a hydroxyl number of less than or equal to 56 mg KOH/g polyol, and containing less than or equal to 20% of copolymerized oxyethylene, based on the total weight of the monofunctional polyether (a)(i);
(ii) a polyether polyol having a hydroxyl number of from 47 mg KOH/g polyol to 300 mg KOH/g polyol, a nominal functionality of 2, and containing from 5 to 45% of copolymerized oxyethylene, based on the total weight of said polyether polyol (a)(ii);
and
(iii) a polyether polyol having a hydroxyl number of from 47 mg KOH/g polyol to 300 mg KOH/g polyol, a nominal functionality of greater than 2 to 8, and containing from 5 to 45% of copolymerized oxyethylene, based on the total weight of said polyether polyol (a)(iii);
wherein (a) said polyol blend comprises 20 to 50% by weight of (i) said monofunctional polyether and the balance comprises components (ii) and
(iii) in which from 10 to 90% by weight of the balance comprises component (ii) and from 90 to 10% by weight of the balance comprises component (iii);

and, optionally,
(b) up to 80% by weight, based on 100% by weight of components (2)(a) and (2)(b), of a polyether polyol having an average functionality of from 2 to 8, a hydroxyl number of from 20 mg KOH/g polyol to 300 mg KOH/g polyol and containing at least 50% of copolymerized oxyethylene, based on the total weight of said polyether polyol (2)(b);

and
(3) a hydroxyl-terminated prepolymer comprising the reaction product of:
(a) a diisocyanate and/or a polyisocyanate component,
with
(b) an isocyanate-reactive component comprising:
(i) a polyether polyol having a nominal functionality of about 3, and a hydroxyl number ranging from 100 to 200,
or
(ii) castor oil,
wherein the equivalent ratio of (3)(b) said isocyanate-reactive component to (3)(a) said diisocyanate and/or polyisocyanate component (a) ranges from 5:1 to 10:1;

in the presence of
(4) a blowing agent;
(5) a catalyst;
and
(6) a surfactant.

2. The process of claim 1 , wherein (3) said hydroxyl-terminated prepolymer comprises the reaction product of:
(a) a diisocyanate and/or a polyisocyanate component,
with
(b) an isocyanate-reactive component comprising:
(i) a polyether polyol having a nominal functionality of about 3, and a hydroxyl number ranging from 100 to 200,

and the resultant hydroxyl-terminated prepolymer has a viscosity of less than 2500 mPa·s@25° C.

3. The process of claim 2 , wherein said hydroxyl-terminated prepolymer has a viscosity of less than 2000 mPa·s@25° C.

4. The process of claim 1 , wherein said hydroxyl-terminated prepolymer is prepared at an equivalent ratio of (3)(b) the isocyanate-reactive component to (3)(a) the diisocyanate and/or polyisocyanate component in the range from 5:1 to 6:1.

5. The process of claim 1 , wherein (3)(a) said polyisocyanate component comprises a polymeric diphenylmethane diisocyanate having a monomeric MDI content of greater than 45% by weight.

6. The process of claim 5 , wherein said polymeric diphenylmethane diisocyanate has a monomeric MDI content of at least 60% by weight.

7. The process of claim 1 , wherein (3)(b)(i) said polyether polyol comprises the reaction product of a starter compound with propylene oxide in the presence of a catalyst.

8. The process of claim 1 , wherein (3)(b)(i) said polyether polyol comprises the reaction product of a starter compound with an alkylene oxide in the presence of a catalyst, wherein said alkylene oxide comprises a mixture of ethylene oxide and propylene oxide in a weight ratio of greater than 0:100 to 50:50.

9. The process of claim 1 , wherein (2)(a) said polyol blend has a hydroxyl number of from 70 mg KOH/g polyol to less than 120 mg KOH/g polyol and an average functionality of at least 2.1.

10. The process of claim 1 , wherein the resultant viscoelastic flexible polyurethane foam has a 90% compression set of about 10% or less and a 25% IFD value of at least 9 lbf, as measured by ASTM D-574-11.

11. The process of claim 10 , wherein the resultant viscoelastic flexible polyurethane foam additionally has a ratio of storage modulus at 15° C. to the storage modulus at 30° C. of less than or equal to 5 and a T g of less than 20° C. as measured by tan delta.

12. The process of claim 1 , wherein (2) said isocyanate-reactive component additionally comprises at least one of:
(c) a polyether polyol having an hydroxyl number of from 10 mg KOH/g polyol to 300 mg KOH/g polyol, an average functionality of from 2 to 8, and which contains from 0 to 45% by weight of copolymerized oxyethylene, based on 100% by weight of component (2)(c), wherein polyether polyol (2)(c) is different than polyether polyols (2)(a)(ii) and (2)(a)(iii);
and/or
(d) a filled polyol.

13. The process of claim 1 , wherein (2)(a) said polyol blend comprises an in-situ formed polyol blend.

14. A viscoelastic flexible polyurethane foam comprising the reaction product of:
(1) a diisocyanate or polyisocyanate component,
(2) an isocyanate-reactive component comprising:
(a) from 20 to 100% by weight, based on 100% by weight of components (2)(a) and (2)(b), of a polyol blend having a hydroxyl number of from 56 mg KOH/g polyol to about 250 mg KOH/g polyol, an average functionality of greater than 2, and comprising:
(i) a monofunctional polyether having a hydroxyl number of less than or equal to 56 mg KOH/g polyol, and containing less than or equal to 20% of copolymerized oxyethylene, based on the total weight of said monofunctional polyether (a)(i);
(ii) a polyether polyol having a hydroxyl number of from 47 mg KOH/g polyol to 300 mg KOH/g polyol, a nominal functionality of 2, and containing from 5 to 45% of copolymerized oxyethylene, based on the total weight of said polyether polyol (a)(ii);
and
(iii) a polyether polyol having a hydroxyl number of from 47 mg KOH/g polyol to 300 mg KOH/g polyol, a nominal functionality of greater than 2 to 8, and containing from 5 to 45% of copolymerized oxyethylene, based on the total weight of said polyether polyol (a)(iii);

wherein (2)(a) said polyol blend comprises 20 to 50% by weight of (i) said monofunctional polyether and the balance comprises components (ii) and (iii) in which from 10 to 90% by weight of the balance comprises component (ii) and from 90 to 10% by weight of the balance comprises component (iii);
and, optionally,
(b) up to 80% by weight, based on 100% by weight of components (2)(a) and (2)(b), of a polyether polyol having an average functionality of from 2 to 8, a hydroxyl number of from 20 mg KOH/g polyol to 300 mg KOH/g polyol and containing at least 50% of copolymerized oxyethylene, based on the total weight of said polyether polyol (2)(b);
and

(3) a hydroxyl-terminated prepolymer comprising the reaction product of:
(a) a diisocyanate and/or a polyisocyanate component,
with
(b) an isocyanate-reactive component comprising:
(i) a polyether polyol having a nominal functionality of about 3, and a hydroxyl number of from 100 to 200,
or
(ii) castor oil,

wherein the equivalent ratio of (3)(b) said isocyanate-reactive component to (3)(a) said diisocyanate and/or polyisocyanate component (a) ranges from 5:1 to 10

Assignees

• Covestro Llc

Inventors

• Barksby Nigel
• Neal Brian L

Classifications

• C08G2110/0008

  flexible · CPC title

• C08G2110/0083

  prepared using water as the sole blowing agent · CPC title

• C08G2110/0058

  ≥50 and <150kg/m3 · CPC title

• C08G18/4837

  and other oxyalkylene units · CPC title

• C08J2371/02

  Polyalkylene oxides · CPC title