Hydrophilic composite

Abstract

Hydrophilic composite structures are made by impregnating a 3DL structure with a polyurethane foam formulation and curing the formulation to produce a foam that occupies the spaces in the 3DL structure. The composite structures have an unusually good capacity for retaining water even when under compressive forces. They also exhibit at most moderate swelling when saturated with water. The foam is useful as a layer of a water containment system such as a green roof or blue roof system.

Claims

1. A water containment system comprising a composite structure comprising: (a) a three-dimensional random loop (3DL) structure comprising a plurality of random loops of a thermoplastic polymer arranged and bonded together in a three-dimensional orientation and defining spaces within the 3DL structure; and (b) a hydrophilic polyurethane foam that occupies substantially all of the spaces in the 3DL structure, wherein the 3DL structure has an apparent bulk density of 0.005 g/cm.sup.3 to 0.2 g/cm.sup.3.

2. A water containment system comprising at least one water barrier layer, at least one layer of a composite structure directly or indirectly on top of at least a portion of the water barrier layer, and at least one top surface layer positioned directly or indirectly on top of at least a portion of the hydrophilic foam layer, the water containment system comprising drainage means for draining water falling upon the top surface layer to the hydrophilic foam layer, wherein the composite structure comprises (a) a three-dimensional random loop (3DL) structure comprising a plurality of random loops of a thermoplastic polymer arranged and bonded together in a three-dimensional orientation and defining spaces within the 3DL structure; and (b) a hydrophilic polyurethane foam that occupies substantially all of the spaces in the 3DL structure, wherein the 3DL structure has an apparent bulk density of 0.005 g/cm.sup.3 to 0.2 g/cm.sup.3.

3. The water containment system of claim 2 wherein the top surface layer includes soil and vegetation layers and the drainage means include pores in the soil layer in fluid communication with the composite structure.

4. The water containment system of claim 3 wherein the hydrophilic polyurethane foam layer has one or more channels on a bottom surface, which channels form pathways through which water can flow and be removed from the water containment system.

5. The water containment system of claim 3 further comprising a support structure directly or indirectly below the water barrier layer.

6. The water containment system of claim 5 wherein the support structure is a roof structure.

7. A water containment system comprising a support structure, at least one water barrier layer directly or indirectly above at least a portion of the support structure, at least one layer of a composite structure directly or indirectly on top of at least a portion of the water barrier layer, a separation fabric directly or indirectly on top of at least a portion of the hydrophilic polyurethane foam layer and at least one top surface layer positioned directly or indirectly on top of at least a portion of the separation fabric, the water containment system comprising drainage means for draining water falling upon the top surface layer to the hydrophilic foam layer, wherein the composite structure comprises (a) a three-dimensional random loop (3DL) structure comprising a plurality of random loops of a thermoplastic polymer arranged and bonded together in a three-dimensional orientation and defining spaces within the 3DL structure; and (b) a hydrophilic polyurethane foam that occupies substantially all of the spaces in the 3DL structure, wherein the 3DL structure has an apparent bulk density of 0.005 g/cm.sup.3 to 0.2 g/cm.sup.3.

8. The water containment system of claim 7 wherein the hydrophilic polyurethane foam layer has one or more channels on a bottom surface, which channels form pathways through which water can flow and be removed from the water containment system.

Description

EXAMPLE 1 AND COMPARATIVE SAMPLES A-B

(1) 3DL A is an ethylene--olefin copolymer 3-dimensional loop structure having a density of 2 pounds per cubic foot. It is made according to the general method described in WO 2016/130602.

(2) 3DL B is an ethylene--olefin copolymer 3-dimensional loop structure having a density of 3 pounds per cubic foot. It is made according to the general method described in WO 2016/130602.

(3) Foam Formulation A (FF-A) contains an isocyanate-terminated quasi-prepolymer, water and surfactants. The quasi-prepolymer contains 40% oxyethylene units and has an isocyanate content of about 7%. The water index is approximately 10,000.

(4) Foam Formulation B (FF-B) contains an isocyanate-terminated quasi-prepolymer, water and surfactants. The quasi-prepolymer contains 63% oxyethylene units and has an isocyanate content of about 7%. The water index is approximately 10,000.

(5) Foam Formulation C (FF-C) contains an isocyanate-terminated quasi-prepolymer, water and surfactants. The quasi-prepolymer contains 58% oxyethylene units and has an isocyanate content of about 10%. The water index is approximately 2,000.

(6) Comparative Foams A-C and Foam Examples 1-6 are prepared by mixing the ingredients of the respective foam formulation to from a reaction mixture. The resulting reaction mixture in each case is poured into a 11.2 cm11.2 cm2.54 cm open mold and allowed to rise freely. For Examples 1-6, the mold contains either 3DL A or 3DL B, cut to fit the internal cavity of the mold, when the reaction mixture is poured into the mold. The 3DL material is held in place within the mold so it cannot rise with the rising foam formulation. The foam formulation rises and cures to form a foam that occupies the entire internal space of the 3DL material (when present) and fills the mold. After the foaming is complete the composite is allowed to rest for 10 minutes. The crown is removed to produce an 11.2 cm11.2 cm2.54 cm composite structure.

(7) The composite structures are conditioned overnight at ambient temperature and humidity before performing property testing. Water holding, water retention and swelling are measured as described above. Results of the testing are as indicated in the following Tables 1-3.

(8) TABLE-US-00001 TABLE 1 Composite Structures Made with Foam Formulation A Designation Comp. A* Ex. 1 Ex. 2 FF-A, parts by weight 100 67.4 60.2 3DL, type, parts by weight None A, 32.6 B, 39.8 Water holding (no applied pressure), 227 182 164 g/2.54 cm thickness Water retention, %, under applied pressures as follow: 50 lb/ft.sup.2 (2.394 kPa) 87 92 98 75 lb/ft.sup.2 (3.591 kPa) 67 80 84 112.5 lb/ft.sup.2 (5.387 kPa) 56 72 79 150 lb/ft.sup.2 (7.182 kPa) 44 62 70 Total Swelling, % 153 62 47

(9) TABLE-US-00002 TABLE 2 Composite Structures Made with Foam Formulation B Designation Comp. B* Ex. 3 Ex. 4 FF-B, parts by weight 100 70.1 60.7 3DL, type, parts by weight None A, 29.9 B, 39.3 Water holding (no applied pressure), 192 160 156 g/2.54 cm thickness Water retention, %, under applied pressures as follow: 50 lb/ft.sup.2 (2.394 kPa) 97 96 97 75 lb/ft.sup.2 (3.591 kPa) 94 93 94 112.5 lb/ft.sup.2 (5.387 kPa) 01 90 92 150 lb/ft.sup.2 (7.182 kPa) 81 82 86 Total Swelling, % 112 56 37

(10) TABLE-US-00003 TABLE 3 Composite Structures Made with Foam Formulation C Designation Comp. C* Ex. 5 Ex. 6 FF-C, parts by weight 100 65.6 55.1 3DL, type, parts by weight None A, 34.4 B, 44.9 Water holding (no applied pressure), 193 183 172 g/2.54 cm thickness Water retention, %, under applied pressures as follow: 50 lb/ft.sup.2 (2.394 kPa) 87 86 91 75 lb/ft.sup.2 (3.591 kPa) 57 69 77 112.5 lb/ft.sup.2 (5.387 kPa) 46 53 69 150 lb/ft.sup.2 (7.182 kPa) 36 45 56 Total Swelling, % 74 40 27

(11) As the data in Tables 1-3 show, incorporating a 3DL structure into foams produced by any of Foam Formulations A-C has little effect on water holding. However, total swelling is reduced substantially with Examples 1-6, as compared to the corresponding comparative samples. Also, water holding under pressure is equal or improved in all instances, even when the foam formulation is adapted (as is Foam Formulation B) to have very good water holding power under pressure. The combination of initial water holding capacity, ability to hold the water under pressure and low swelling is highly beneficial and not obtained with any of the hydrophilic foams by themselves.