Flame Retardant Mechanical Foam

Abstract

One or more embodiments of the present invention provides a process for the preparation of a coating or layer on a substrate, in which process a mixture comprising one or more polyurethane dispersions, one or more flame retardants, which can be halogen-based or halogen-free, one or more foam stabilizers and optionally one or more crosslinkers is mechanically foamed and then applied on a substrate as a foam, optionally followed by adding flocking fibres, and subsequently dried, wherein the foam has flame retardant properties and remains present as a stable pressure resistant dried foam.

Claims

1. A process for applying a coating or layer onto a substrate, comprising the steps of: a) providing a formulation mixture comprising: one or more polyurethane dispersions, one or more flame retardants selected from halogen-based or halogen-free, one or more foam stabilizers; b) mechanically foaming said mixture; c) applying said foam onto the substrate as a foam; and d) subsequently drying.

2. The process of claim 1 wherein the formulation mixture further comprises one or more crosslinkers.

3. The process of claim 1 further comprising adding flocking fibres after the foam is applied to the substrate prior to the drying step.

4. The process of claim 1, wherein the dried foam has a medium foam density of between about 160 g/L and about 1599 g/L.

5-6. (canceled)

7. The process of claim 2, wherein the one or more crosslinkers are selected from the group consisting of polycarbodiimide crosslinker, isocyanate crosslinker, aziridine crosslinker or polyurea crosslinker or a combination thereof

8. The process of claim 7 wherein the one or more crosslinkers is an aqueous polycarbodiimide crosslinkers or 100% solids polycarbodiimide crosslinkers.

9. The process of claim 7 wherein at least one polycarbodiimide crosslinker is present in combination with one or more other types of crosslinkers.

10. The process of claim 1, wherein the one or more flame retardants are present in an amount per coated surface area of between about 20 g/m.sup.2 and about 80 g/m.sup.2.sub.−.

11. (canceled)

12. The process of claim 1, wherein the one or more polyurethane dispersions and the one or more flame retardants are used in the formulation mixture in a ratio of between about 80:20 to about 20:80, where the ratio is based on weights of both component groups.

13. The process according to claim 1, wherein the one or more flame retardants are selected from tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), tris(1,3-dichloro-2-propyl) phosphate (TDCP), dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), triaryl phosphates such as triphenyl phosphate, isopropylphenyl diphenyl phosphate, tricresyl phosphate and trixylenyl phosphate, ammoniumpolyphosphate (APP), stabilized red phosphorus, aluminum hydroxide (ATH), graphite flakes, diphosphates or oligomeric phosphates or phosphonates, diammonium hydrogen phosphate (coated and uncoated), pentabromodiphenyl ether, tetrabromobenzoate ester, tris(butoxyethyl) phosphate, diphenyl octyl phosphate and other diphenyl alkyl phosphates.

14. The process of claim 1 wherein no flame retardant of the intumescent type such as (expandable) graphite is present.

15. The process of claim 1 wherein a flame retardant of the intumescent type such as (expandable) graphite is present in an amount of maximum 20 wt % based on the formulation mixture together with another type of flame retardant.

16. The process of claim 1, wherein the one or more foam stabilizers comprises one or more cationic surfactants, anionic surfactants, or non-ionic surfactants, or combinations thereof.

17. The process of claim 1, wherein the one or more foam stabilizers is a carboxylic acid salt which may be represented by the general formula RCO.sub.2.sup.−X.sup.+, where R represents a C.sub.8-C.sub.20 linear or branched alkyl, which can contain an aromatic, a cycloaliphatic, or heterocycle; and X is a counter ion such as sodium, potassium or an amine.

18. The process of claim 1, wherein the foam is applied onto the substrate at a coating weight of between about 10 g/m.sup.2 and about 1000 g/m.sup.2.

19. (canceled)

20. The process of claim 1, wherein drying is performed at a temperature between about 10° C. and about 170° C.

21. (canceled)

22. The process of claim 1 wherein drying is performed at a first elevated temperature of between about 10° C. and about 100° C followed by drying at a second higher temperature of between about 100° C. and about 120° C.

23-24. (cancel)

25. The process of claim 1, wherein the one or more polyurethane dispersions are aqueous polyurethane dispersions.

26. The process of claim 1 wherein the one or more polyurethane dispersions are aqueous polyurethane dispersions having a solid level of between about 25% to about 65% by weight.

27. (canceled)

28. The process of claim 1, wherein the mechanically foamed mixture is obtained by mechanical stirring at high speeds.

29. The process of claim 1, wherein the substrate is non-rigid.

30. The process of claim 1 wherein the substrate is selected from woven textiles, non-woven textiles, knits, synthetic leather, natural leather, finished natural leather, coated leather, coated polyvinyl chloride, coated non-woven, coated coagulated polyurethane substrates, polypropylene, polyethylene terephthalate, polyolefines, modified polyolefins or laminated structures.

31. The process of claim 1, wherein no fluorochemical is present in the formulation mixture or present in amounts below about 1 wt % of the formulation mixture.

32. A coated substrate made by the process of claim 1.

33. The coated substrate of claim 32 wherein the coating is a pressure resistant dried foam and not a resilient foam.

34. The coated substrate of claim 32 wherein said coated surface passes the requirements of one or more flame tests selected from British Standard BS 5852:2006 specific to upholstered furniture, FAR 25.853 specific for fabrics in aviation, German Standards Fire Resistance test DIN4102 for building materials and elements, British Standard BS 5867-2:2008 for fabrics for fabrics for curtains, drapes and window blinds, French FR Standard NF P 92503-507, fabric FR test for French contract industry (also known as M1).

35. A layered structure of which at least one layer comprises the coated substrate of claim 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

EXAMPLES

[0046] Example 1: Aviation Test Method—Comparison with Paste Coating.

[0047] A mixture of 50 parts of Permutex RU-92-213 (a polyurethane dispersion, obtainable from Stahl Europe BV), 50 parts of Eagleban FRC-0387 (a product containing uncoated di-ammonium hydrogen phosphate as flame retardant, obtainable from Stahl Europe BV), 7 parts of a 30% solution of ammonium stearate in water and 1 part of Permutex XR-13-554 (a polycarbodiimide crosslinker, obtainable from Stahl Europe BV) was made. The mixture was mechanically foamed and the resulting foam was applied on an aviation fabric (produced with hydro-entanglement and fibres). The foam was subsequently dried at 80° C. during 4 minutes and, to speed up the drying, then at 120° C. during 2 minutes.

[0048] As reference, a paste containing Eagleban FRC-0387 (a product containing di-ammonium hydrogen phosphate as flame retardant, obtainable from Stahl Europe BV) was used. The reference was applied on an aviation fabric (produced with hydro-entanglement and fibres). The paste was subsequently dried at 80° C. during 4 minutes and then at 120° C. during 2 minutes.

[0049] Specimens of both samples were multiple times subjected to an aviation burning test according to FAR 25.853. The test takes place in a specified test chamber in which the specimen is mounted vertically. The centre of the bottom edge of the specimen is exposed to a gas flame for 12 seconds. The after burn time (ABT) and burn length (BL) is recorded.

[0050] The results table displays also the layer thickness that was applied, as g/m.sup.2 of wet material. The g/m.sup.2 of FRC-0387 that was thus applied was calculated from the g/m.sup.2 of wet material and the concentration in the wet material. The concentration of FRC-0387 in the foam wet material is 46%, whereas in the paste wet material it is 100%.

TABLE-US-00001 ABT BL specimen g/m.sup.2 (sec) (cm) g/m.sup.2 of FRC-0387 Foam - specimen 1 56 14 11 25.8 Foam - specimen 2 52 4 4 23.9 Foam - specimen 3 48 13 8 22.1 Foam - specimen 4 56 4 3.5 25.8 Foam - specimen 5 60 15 7 27.6 Foam - specimen 6 58 11 5 26.7 Average Foam 55 10.2 6.4 25.3 Paste - specimen 1 86 14 1.5 77.4 Paste - specimen 2 88 19 3.2 79.2 Paste - specimen 3 102 17 4 91.8 Paste - specimen 4 94 17 4.5 84.6 Paste - specimen 5 20 2.6 Paste - specimen 6 19 2.7 Paste - specimen 7 13 2.7 Paste - specimen 8 17 2.8 Average Paste 17.0 3.0

[0051] The average burn time (ABT) of the foam specimens was on average 10.2 seconds, whereas for the paste specimens the average was 17.0 seconds. According to the FAR 25.853 test method, all specimens of a series must have a burn length that is 20.3 cm or less, and an after burn time of 15 seconds or shorter. Therefore, the foam specimens pass the test, whereas the paste specimens fail. The foam specimens carry a lower amount of flame retardant per surface area than the paste specimens, and still the foam specimens give a much better performance in the FAR 25.853 test.

[0052] Example 2: Upholstery Test Method—Comparison with Collapsible Foam

[0053] A mixture of 50 parts of Permutex RU-92-213 (a polyurethane dispersion, obtainable from Stahl Europe BV), 50 parts of Eagleban FRC-0387 (a product containing uncoated di-ammonium hydrogen phosphate as flame retardant, obtainable from Stahl Europe BV), 7 parts of a 30% solution of ammonium stearate in water was made. The mixture was mechanically foamed by mixing at high speed with a stirrer to a density of 200 g/L, and the resulting foam was applied on a 100% polyester-based velour textile, in a layer thickness to achieve a dried layer quantity of 100 g/m.sup.2. The foam was subsequently dried at 80° C. during 4 minutes and, to speed up the drying, then at 110° C. for 2 minutes. Permutex RU-92-213 has a solids content of 60%. Eagleban FRC-0387 has a solids content of 52.5%, of which 7.5% is a polymeric resin and 45% is from fillers, including the flame retardant component(s). The mixture of 50 parts Permutex RU-92-213 and 50 parts Eagleban FRC-0387 thus contains 56 parts of solids, of which 22.5 parts are from the fillers in Eagleban FRC-0387. Thus, the percentage of these fillers, in which the flame retardant component(s) are included, in the dried coating was 40%.

[0054] As reference, a mixture was made of 30 parts of Permutex RU-92-213 (a polyurethane dispersion, obtainable from Stahl Europe BV) and 70 parts of Eagleban FRC-0387 (a product containing di-ammonium hydrogen phosphate as flame retardant, obtainable from Stahl Europe BV). The mixture was foamed to a density of 200 g/L and the resulting collapsible foam was applied on a 100% polyester-based velour textile, in a layer thickness to achieve a dried layer quantity of 100 g/m.sup.2. The foam was subsequently dried at 80° C. during 4 minutes and then at 110° C. for 2 minutes, upon which the foam collapsed. Permutex RU-92-213 has a solids content of 60%. Eagleban FRC-0387 has a solids content of 52.5%, of which 7.5% is a polymeric resin and 45% is from fillers, including the flame retardant component(s). The mixture of 30 parts Permutex RU-92-213 and 70 parts Eagleban FRC-0387 thus contains 55 parts of solids, of which 31.5 parts are from the fillers in Eagleban FRC-0387. Thus, the percentage of these fillers, in which the flame retardant component(s) are included, in the dried coating was 57%.

[0055] Specimens of both samples were subjected to an upholstery burning test according to BS 5852 match test. In this test method, a test rig is constructed in order to simulate a chair with the fabric to be tested. A simulated match burner is lit, held along the crevice of the test rig for 20 seconds and then removed. No flaming is allowed to continue for more than 120 seconds after removal of the burner tube and the test assembly is not allowed to smoulder after one hour from the beginning of the test.

[0056] The specimen of the foam sample passed the test, whereas the reference specimen of the collapsible foam failed the test, while the dried layer quantity was the same for both but the amount of fillers, in which the flame retardant component(s) are included, in the dried coating was 40% in the foam sample and 57% in the reference sample.

[0057] Example 3: Upholstery Test Method—Comparison with Collapsible Foam

[0058] A mixture of 50 parts of Permutex RU-92-213 (a polyurethane dispersion, obtainable from Stahl Europe BV), 50 parts of Eagleban FRC-0387 (a product containing uncoated di-ammonium hydrogen phosphate as flame retardant, obtainable from Stahl Europe BV), 7 parts of a 30% solution of ammonium stearate in water and 1 part of Permutex XR-13-554 (a polycarbodiimide crosslinker, obtainable from Stahl Europe BV) was made. The mixture was mechanically foamed to a density of 200 g/L, and the resulting foam was applied on a 100% polyester-based textile, in a layer thickness of 0.95 mm using a knife blade. The foam was subsequently dried at 80° C. during 4 minutes and, to speed up the drying, subsequently at 120° C. during 2 minutes. Permutex RU-92-213 has a solids content of 60%. Permutex XR-13-554 has a solids content of 100%. Eagleban FRC-0387 has a solids content of 52.5%, of which 7.5% is a polymeric resin and 45% is from fillers, including the flame retardant component(s). The mixture of 50 parts Permutex RU-92-213, 50 parts Eagleban FRC-0387 and 7 parts of a 30% solution of ammonium stearate in water thus contains 59 parts of solids, of which 22.5 parts are from the fillers in Eagleban FRC-0387. Thus, the percentage of these fillers, in which the flame retardant component(s) are included, in the dried coating is 38%. A thickness of 0.95 mm, a foam density of 200 g/L and a solids content of the mixture of 59% resulted in a dried layer quantity of 112 g/m.sup.2. The contribution of these fillers, in which the flame retardant component(s) are included, in the dried coating was thus 43 g/m.sup.2.

[0059] Specimen of the sample was subjected to an upholstery burning test according to BS 5852 Crib 5 test. As stipulated in BS 5852, all specimens underwent a water soaking procedure in accordance with BS5852:2006 Annex E, as a pre-treatment, before testing, followed by line drying. The BS 5852:2006 Crib 5 test on a cover fabric is performed in a test cabinet with a calibrated airflow. The cover fabric and the filling are put in a test rig to create a small sofa with a 90° angle between seat and back. The filling material is a combustion modified polyurethane foam. The ignition source is located in the junction between seat and back. Ignition source 5 is a wooden crib composed of 20 wooden sticks, glued together and with a total weight of 17 g. After adding propane-diol, the crib is placed on the test rig and ignited with a match. The test assembly is not allowed to smoulder for more than 60 minutes from the start of the test. The test assembly is not allowed to show evidence of charring more than 100 mm in any direction apart from upwards from the ignition source. No flaming is allowed to continue for more than 10 minutes after start of the test with ignition source 5.

[0060] The specimen of the foam sample passed the test, as the flaming stopped after 6 minutes and charring was only 30 mm, which is well within the limits of 10 minutes and 100 mm, respectively.

[0061] Specimen of the reference also passed the test, wherein the reference was made from a brominated system, which was applied with a dried layer quantity of 150 g/m.sup.2, and in the brominated system about 90% of the solids was from the flame retardant components. The contribution of the flame retardant components in the dried coating was thus 135 g/m.sup.2.

[0062] The specimen of the foam sample and the specimen of the reference passed the test, while the amount of fillers, in which the flame retardant component(s) are included, in the dried coating of the foam sample was only 43 g/m.sup.2, whereas the contribution of the flame retardant components in the dried coating was 135 g/m.sup.2 in the reference sample.

[0063] Example 4: Upholstery Test Method—Water Uptake

[0064] Two specimen, prepared as described in Example 3, on two different fabrics were subjected to a water soaking test, as the test according to BS 5852:2006, all interliners and cover fabrics that have been treated with a flame retardant shall go through a water soaking procedure in accordance with BS5852:2006 Annex E, as a pre-treatment, before testing, followed by line drying. Pieces of 26 by 76 cm of the specimens were immersed for 30 minutes in water of 40° C., where the amount of water was 20 times the weight of the specimens. The specimens and the fabrics themselves were soaked and dried. The moisture uptake of the coating layer was calculated by subtracting the moisture uptake of the fabric from the moisture uptake of the coated fabric. The values were then calculated from grams into g/m.sup.2 taking into account the surface area of the specimens.

[0065] The first specimen was constructed of a fabric of 390 g/m.sup.2 and a foamed coating layer of 124 g/m.sup.2. The initial moisture uptake, before drying, was 1115 g/m.sup.2 for the fabric layer and 200 g/m.sup.2 for the foamed coating layer. After 24 hours of line drying, the moisture uptake was 7.2 g/m.sup.2 for the fabric layer and 400/m.sup.2 g for the foamed coating layer. After 48 hours of line drying, the moisture uptake was 0 g/m.sup.2 for the fabric layer and 74 g/m.sup.2 for the foamed coating layer.

[0066] The second specimen was constructed of a fabric of 236 g/m.sup.2 and a foamed coating layer of 129 g/m.sup.2. The initial moisture uptake, before drying, was 493 g/m.sup.2 for the fabric layer and 280 g/m.sup.2 for the foamed coating layer. After 24 hours of line drying, the moisture uptake was 2.3 g/m.sup.2 for the fabric layer and 28 g/m.sup.2 for the foamed coating layer. After 48 hours of line drying, the moisture uptake was 0 g/m.sup.2 for the fabric layer and 168 g/m.sup.2 for the foamed coating layer.

[0067] The results of both specimens demonstrate that the foamed coating layer can still hold a substantial amount of moisture after 24 hours or 48 hours of line drying, which is beneficial for the BS 5852:2006 test.

[0068] Example 5: Upholstery Test Method

[0069] The procedure of Example 3 was followed, except that in addition also 10 solid parts of graphite was added as an additional flame retardant, besides the 50 parts of Eagleban FRC-0387. Specimen of the foam sample passed the BS 5852 Crib 5 test, as the flaming stopped after 5 minutes and the charring length was only 30 mm, which is well within the limits of 10 minutes and 100 mm, respectively. However the results were not improved vis-à-vis Example 3 wherein no graphite was used. Hence the foam of the present invention shows excellent barrier properties for crib 5 test, without a significant amount of graphite being present.

[0070] Example 6: Layer Thickness—Comparison with Crushed Foam

[0071] A mixture of 50 parts of Permutex RU-92-213 (a polyurethane dispersion, obtainable from Stahl Europe BV), 50 parts of Eagleban FRC-0387 (a product containing uncoated di-ammonium hydrogen phosphate as flame retardant, obtainable from Stahl Europe BV), 7 parts of a 30% solution of ammonium stearate in water and 3 parts of Permutex XR-13-554 (a polycarbodiimide crosslinker, obtainable from Stahl Europe BV) was made. The mixture was mechanically foamed to a density of 200 g/L, and the resulting foam was applied on a Leneta Card, in a layer thickness of 1 mm using a knife blade. The foam was subsequently dried at 80° C. during 3 minutes. The thickness of the Lenata Card was 0.35 mm and the thickness of the Leneta Card including the dried foam was 0.85 mm, which means that the thickness of the foam layer was 0.50 mm.

[0072] Another specimen of a dried layer of foam on Leneta Card was prepared as described above. Subsequently, a pressure of 4 bar was applied on the dried foam layer using a cyclinder. The thickness of the Lenata Card was 0.35 mm and the thickness of the Leneta Card including the dried foam was 0.85 mm, which means that the thickness of the foam layer was 0.50 mm.

[0073] As reference, a mixture of 50 parts of Permutex RA-9260 (a polyacrylic dispersion, obtainable from Stahl Europe BV), 50 parts of Eagleban FRC-0387 (a product containing uncoated diammonium phosphate as flame retardant, obtainable from Stahl Europe BV), 7 parts of a 30% solution of ammonium stearate in water and 3 parts of Permutex XR-13-554 (a polycarbodiimide crosslinker, obtainable from Stahl Europe BV) was made. The mixture was mechanically foamed to a density of 200 g/L, and the resulting foam was applied on a Leneta Card, in a layer thickness of 0.6 mm using a knife blade. The foam was subsequently dried at 80° C. during 3 minutes. A pressure of 4 bar was applied on the dried foam layer using a cyclinder to crush the foam. The thickness of the Lenata Card was 0.37 mm and the thickness of the Leneta Card including the crushed foam was 0.44 mm, which means that the thickness of the crushed foam layer was 0.07 mm. Another specimen of the reference was dried at 80° C. during 3 minutes followed by drying at 150° C. during 2 minutes. A pressure of 4 bar was applied on the dried foam layer using a cyclinder to crush the foam. The thickness of the Lenata Card was 0.37 mm and the thickness of the Leneta Card including the crushed foam was 0.46 mm, which means that the thickness of the crushed foam layer was 0.09 mm.

[0074] Note that in the specification and claims, “about” or “approximately” means within twenty percent (20%) of the numerical amount cited. The singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0075] Although the invention has been described in detail with particular reference to these embodiments, other embodiments can achieve the same results. Variations and modifications of an embodiment of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference.