US 12,258,438 B2
Process for making a flexible polyurethane foam having a hardness gradient
Mark Joseph Brennan, Aarschot (BE); Chingchung Vincent Huang, Shanghai (CN); Zhicheng George Tian, Shanghai (CN); Alain Germain Marc Veys, Deggendorf (DE); and Mario Unverdorben, Deggendorf (DE)
Assigned to HUNTSMAN INTERNATIONAL LLC
Appl. No. 17/619,272
Filed by Huntsman International LLC, The Woodlands, TX (US)
PCT Filed Jun. 19, 2020, PCT No. PCT/EP2020/067062
§ 371(c)(1), (2) Date Dec. 15, 2021,
PCT Pub. No. WO2020/260145, PCT Pub. Date Dec. 30, 2020.
Claims priority of application No. 19182576 (EP), filed on Jun. 26, 2019.
Prior Publication US 2022/0227918 A1, Jul. 21, 2022
Int. Cl. B29C 39/00 (2006.01); B29C 39/12 (2006.01); B29C 39/36 (2006.01); C08G 18/08 (2006.01); C08G 18/10 (2006.01); C08G 18/18 (2006.01); C08G 18/40 (2006.01); C08G 18/48 (2006.01); C08G 18/63 (2006.01); C08G 18/76 (2006.01); B29K 75/00 (2006.01); C08G 101/00 (2006.01)
CPC C08G 18/7671 (2013.01) [B29C 39/003 (2013.01); B29C 39/12 (2013.01); B29C 39/36 (2013.01); C08G 18/14 (2013.01); C08G 18/1825 (2013.01); C08G 18/4816 (2013.01); C08G 18/4841 (2013.01); B29K 2075/00 (2013.01); C08G 2101/00 (2013.01); C08G 2110/0008 (2021.01); C08G 2110/0041 (2021.01); C08G 2110/0083 (2021.01); C08G 2350/00 (2013.01)] 16 Claims
 
1. A molded flexible polyurethane comprising foam with a hardness gradient, wherein said foam comprises at least:
a top layer which has a thickness which corresponds to around 25% of the total thickness of the foam,
a bottom layer which has a thickness which corresponds to around 25% of the total thickness of the foam,
a foam elasticity Ef in the bottom layer of said foam which is at least 3 times higher than in the top layer of said foam, wherein said foam elasticity for each layer is obtained using a single degree of freedom mass-spring-damper system consisting of a fixed mass and a sample of the foam layer, wherein the foam elasticity for each layer is represented by formula [2]:

OG Complex Work Unit Math
with
ωn=a natural frequency of the foam layer
m=the fixed mass
h=a thickness of the foam layer
A=a cross-section area of the foam layer
and wherein said foam is made using a reactive foam formulation, said reactive formulation formed by mixing at an isocyanate index in the range 70-130:
an isocyanate-reactive composition (a) comprising
a polyether polyol (a1) having an oxypropylene (PO) content of 51-100% by weight, an oxyethylene (EO) content of 0-49% by weight, an average nominal hydroxyl functionality of 2-4 and an average molecular weight of 2000-7000, and
optionally a polyether polyol (a2) having an oxyethylene content of 50-95% by weight, calculated on the weight of this polyol wherein the weight ratio of polyol (a2) in the isocyanate-reactive composition (a) is in the range of 0 to 20% by weight, calculated on the total weight of the isocyanate-reactive composition (a), and
a polyisocyanate composition (b) having an NCO value in the range of 21 up to 25.5% and comprising 0-12% by weight methylene diphenyl 2,4′-diisocyanate (2,4′-MDI) calculated on the total weight of all polyisocyanate compounds in the polyisocyanate composition and a balance of polymeric MDI and methylene diphenyl 4,4′-diisocyanate (4,4′-MDI).