Phyllosilicate-impregnated melamine-formaldehyde foam

Abstract

A melamine/formaldehyde foam having an open-cell foam structure, with an impregnation applied to the foam structure that comprises at least one particulate phyllosilicate surface-modified with aminosilane and at least one anionically- and/or nonionically-stabilized polyurethane dispersion.

Claims

1. An impregnated melamine/formaldehyde foam having an open-cell foam structure, wherein the impregnated melamine/formaldehyde foam is formed by impregnating an unimpregnated melamine/formaldehyde foam with a composition comprising at least one particulate phyllosilicate surface-modified with aminosilane and at least one anionically- and/or nonionically-stabilized polyurethane dispersion, wherein the composition which is impregnated into the foam structure may be dried.

2. The impregnated melamine/formaldehyde foam according to claim 1, wherein the particulate phyllo silicate surface-modified with amino silane has a mean particle diameter in the range from 0.2 to 10 μm (Z mean, determined by light scattering, Malvern, Fraunhofer diffraction).

3. The impregnated melamine/formaldehyde foam according to claim 1, wherein the at least one particulate phyllosilicate surface-modified with aminosilane is applied to the foam structure in an amount of 50 to 350 parts by weight based on 100 parts by weight of unimpregnated melamine/formaldehyde foam.

4. The impregnated melamine/formaldehyde foam according to claim 1, wherein the at least one anionically- and/or nonionically-stabilized polyurethane dispersion is used in an amount of 0.5% to 10% by weight based on the impregnation dry mass.

5. The impregnated melamine/formaldehyde foam according to claim 1, wherein the unimpregnated melamine/formaldehyde foam has a density in the range from 5 to 12 g/l.

6. The impregnated melamine/formaldehyde foam according to claim 1, wherein the density of the impregnated melamine/formaldehyde foam is at least 3 g/l higher than the density of the unimpregnated melamine/formaldehyde foam.

7. The impregnated melamine/formaldehyde foam according to claim 1, wherein the melamine/formaldehyde foam has a molar ratio of formaldehyde to melamine in the range from 5:1 to 1.3:1.

8. The impregnated melamine/formaldehyde foam according to claim 1, wherein the at least one anionically- and/or nonionically-stabilized polyurethane dispersion is an aqueous dispersion of a polyurethane comprising carbodiimide structural units of the formula —N═C═N—.

9. The impregnated melamine/formaldehyde foam according to claim 8, wherein the carbodiimide structural units of the formula —N═C═N— are introduced into the polyurethane via tetramethylxylylene diisocyanate (TMXDI).

10. The impregnated melamine/formaldehyde foam according to claim 8, wherein the content of carbodiimide structural units of the formula —N═C═N— is 5 to 200 ml/kg based on the polyurethane.

11. The impregnated melamine/formaldehyde foam according to claim 1, wherein the composition additionally comprises hydrophobizing and/or oleophobizing agents and/or dispersing agents.

12. The impregnated melamine/formaldehyde foam according to claim 1, wherein an outer surface thereof is at least partially laminated with flat glass-fiber nonwovens, mineral-fiber nonwovens, carbon-fiber nonwovens, carbon-fiber woven fabrics, glass-fiber woven fabrics, mineral-fiber woven fabrics or metal foils.

13. A process for producing an impregnated melamine/formaldehyde foam according to claim 1, comprising the steps of: (a) mixing the at least one particulate phyllo silicate surface-modified with aminosilane with the at least one anionically- and/or nonionically-stabilized polyurethane dispersion and optionally the dispersing agent and the hydrophobizing/oleophobizing agent, (b) applying the mixture from step (a) to the foam, (c) subsequently impregnating the mixture into the pores of the foam to form an impregnated melamine/formaldehyde foam, optionally by compressing the foam, and (d) drying the foam.

14. The process according to claim 13, wherein step d) is carried out at temperatures in the range from 40 to 200° C.

Description

EXAMPLES

(1) Standards and Measurement Methods Used:

(2) Non-Combustibility Test IMO-2010 FTP Code Part 1

(3) This fire test is used to demonstrate the non-combustibility of materials for uses in the shipbuilding sector in accordance with resolution MSC.307 (88)). The test is performed by heating cylindrical test specimens (H=50 mm, ∅45 mm) to 750° C. in an electrically heated furnace in accordance with DIN EN ISO 1182. The test specimens are classified as “non-combustible” if the average temperature difference of the furnace temperature and the average temperature difference of the surface temperature of the test specimen is not more than 30° C. The average loss in mass must not exceed 50% by weight and the observed average duration of ignition is less than 10 seconds.

(4) Evaluation of Adhesion of the Phyllosilicates to the Melamine/Formaldehyde Foam

(5) To assess the adhesion of the particulate phyllosilicate to the melamine/formaldehyde foam, a cylindrical test specimen having a diameter of 45 mm and a height of 50 mm is produced from the melamine/formaldehyde foam. After applying the phyllosilicate to the foam structure and drying, the cylindrical test specimen is manually pushed onto a dark, solid base without breaking up the foam. Separation of the filler (phyllosilicate) from the foam is evidenced by a powdery coating on the hard surface.

(6) Assessment of Water Absorption Based on DIN EN 1609

(7) The DIN EN 13162 standard defines the absorption of water W.sub.p after brief partial immersion in accordance with EN 1609. The test result must not exceed a water absorption of 1.0 kg/m.sup.2. In the drip method according to EN 1609, the initial mass m.sub.0 of the test specimen of the hydrophobized foam of the invention is determined. The test specimen is then placed in an empty water container and weighted so that it remains partially immersed when water is added. Water is then carefully added to the container until the underside of the test specimen is 10 mm below the water level. After 24 hours, the test specimen is removed. After being left to drip for 10 minutes, the test specimen is reweighed and the mass m.sub.24 is determined. The water absorption W.sub.p in kilograms per square meter is calculated as the difference between m.sub.24 and m.sub.0 divided by the bottom surface area of the test specimen A.sub.p in square meters.

(8) Evaluation of Thermal Conductivity in Accordance with DIN EN 12667

(9) The thermal conductivity was measured in accordance with DIN EN 12667 “Thermal performance of building materials and products-Determination of thermal resistance by averages of guarded hot plate and heat flow meter methods-Products of high and medium thermal resistance”.

(10) Oxygen Index in Accordance with ISO 4589-2

(11) The oxygen index (LOI=limiting oxygen index) is a parameter for describing fire behavior, particularly of plastics. It is the minimum oxygen concentration of an oxygen-nitrogen mixture at which the combustion of a vertically positioned test specimen persists under the test conditions. The lower its oxygen index, the more readily a substance burns.

(12) The ingredients below were used in the examples and comparative examples shown below:

(13) General Manufacturing Procedure:

(14) A melamine/formaldehyde foam was produced as described in WO 2012/059493, comparative example A and in accordance with WO 2009/021963. A corresponding foam is obtainable for example from BASF SE under the name Basotect®.

(15) Applying the Impregnation

(16) Impregnation was carried out by immersing a flat blank of a melamine/formaldehyde foam in a dispersion consisting of phyllosilicate, dispersing agent, polyurethane dispersion, and water. After compressing the foam blank multiple times in the dispersion, it was removed from the dispersion and then dried to constant weigh at 130° C. for about 4 h.

(17) A particulate phyllosilicate surface-modified with aminosilane and having an average particle diameter (based on length) of 1.4 μm was used. The product Translink® 445 obtainable from BASF SE was used. Talc with an average particle size (based on length) of 10 μm was additionally used as a dispersing agent. Basotect® UL from BASF SE was also used as the melamine/formaldehyde foam.

(18) Different dispersions listed in the table below were used as the anionically- and/or nonionically-stabilized polyurethane dispersion. Astacin® Finish PUM TF and Astacin® Finish PUMN TF from BASF SE are anionic polyurethane dispersions commonly used in leather finishing. The adhesive raw materials Emuldur® 381 A (40%) and Emuldur® 360 A (40%) from BASF SE are likewise anionic polyurethane dispersions. The anionic aliphatic polyurethane dispersion Impranil® DLV/1 (40%) from Covestro is commonly used in the production of textile coatings in various fields of application. The corresponding compositions are shown in table 1 below.

(19) TABLE-US-00001 TABLE 1 1 2 3 4 5 Starting materials (g) Translink ® 445 2.50 2.50 2.50 2.50 2.50 Talc 10 μm 0.25 0.25 0.25 0.25 0.25 g Astacin ® Finish 0.25 PUM TF (40%) Astacin ® Finish 0.27 PUMN TF (37%) Emuldur ® 381 A 0.25 (40%) Emuldur ® 360 A 0.25 (40%) Impranil ® DLV/1 0.25 (40%) Water 100.00 100.00 100.00 100.00 100.00 Basotect ® UL 0.48 0.47 0.48 0.48 0.48 (6 ± 2 g/L) Result after impregnation Mass (g) 2.2 2.0 2.0 2.2 2.1 Density (g/L) 27.4 25.4 25.4 27.4 26.4

(20) In all tests, an improvement in adhesion compared with systems without binder was observed. This was very good for examples 1 and 4, good for example 5, and moderate for examples 2 and 3.

(21) In a further embodiment, foams according to the invention were obtained by impregnating flat blanks of a melamine/formaldehyde foam in a thickness of 50 mm with a dispersion consisting of phyllosilicate, dispersing agent, polyurethane dispersion, and water and then feeding them through a gap between two counter-rotating rollers (foulard, type Mathis HVF 5) and then drying to constant weight at 130° C. The results are shown below in table 2.

(22) TABLE-US-00002 TABLE 2 6 7 8 9 10 Starting materials (g) Translink ® 445 62.50 62.50 62.50 62.50 62.50 Talc 10 μm 6.25 6.25 6.25 6.25 6.25 Emuldur ® 360 A (40%) 2.50 4.46 6.25 8.03 6.25 Water 2500.00 2500.00 2500.00 2500.00 2500.00 Basotect ® UL (6 g/L) 5.67 5.67 5.71 5.65 5.72 Result after impregnation Mass (g) 19.1 19.3 19.2 19.5 14.9 Density (g/L) 20.2 20.4 20.3 20.6 15.7 Assessment Adhesion of the phyllo- satis- good very very very silicates factory passed good good good Non-combustibility test passed passed not not (IMO 2010 FTP code passed passed part 1)

(23) Formulation 8 shows very good binding of the phyllosilicate and of the dispersing agent in the foam and the requirements of the non-combustibility test in accordance with IMO 2010 FTP code part 1 were met.

(24) In a further embodiment, foams according to the invention were obtained by impregnating flat blanks of a melamine/formaldehyde foam in a thickness of 50 mm with a dispersion consisting of phyllosilicate, polyurethane dispersion, hydrophobizing agent, and water and then feeding them through a gap between two counter-rotating rollers (foulard, type Mathis HVF 5), drying to constant weight at 130° C., and then drying at 170° C. for a further 30 min. The hydrophobizing agent used was Tegosivin HE 328 from Evonik. The results are shown in table 3 below.

(25) TABLE-US-00003 11 Starting materials (g) Translink ® 445 118.75 Tegosivin HE 328 1.25 Emuldur ® 360 A (40%) 5.00 Water 2500.00 Basotect ® UL (6 g/L) 6.16 Result after impregnation Mass (g) 21.7 Density (g/L) 21.2 Assessment Adhesion of the phyllosilicates good Non-combustibility test (IMO 2010 FTP code part 1) passed Water absorption (based on DIN EN 1609) passed Thermal conductivity (mW/m*K, DIN EN 12667) 32.1

(26) Flat blanks of formulation 11 were then laminated with a glass nonwoven (80 kg/m.sup.2). For this, fire-protection adhesive 10300 from IGP GmbH was diluted 1:1 with water and applied homogeneously using a spray gun to the upper side of the formulation 11 test specimen plates. The glass nonwoven was then laid on the still-wet surface and weighed down with a weight without compressing the foam excessively. This was dried to constant weight at room temperature. Application of fire-protection adhesive 10300 at an application rate (dry weight) of 400 g/m.sup.2 achieved good homogeneous adhesion of the glass nonwoven to the formulation 11 foam surface. The thus-laminated component 12 was tested in respect of fire properties and thermal conductivity. The requirements of IMO 2010 FTP code part 1 were met. The thermal conductivity according to DIN EN 12667 is 32.4 mW/m*K.

(27) In similar manner, flat blanks of formulation 11 were laminated on both sides with perforated aluminum foil (surface weight 60 g/m.sup.2, 16 perforations/cm.sup.2). For this, Emuldur 360 A from BASF was diluted with water and applied homogeneously using a spray gun to the upper and lower sides of the formulation 11 test specimen plates. The aluminum foil was then laid on the still-wet surface and weighed down with a small weight without compressing the foam excessively. This was dried to constant weight at room temperature. Application of the binder Emuldur 360 A at an application rate of 35 g/m.sup.2 achieved very good homogeneous adhesion of the aluminum foil to the surface of the formulation 11 foam. The requirements of IMO 2010 FTP code part 1 were met.

(28) In similar manner, samples were also prepared with the binders Hensotherm 2KS from Rudolf Hensel GmbH and the fire-protection adhesive VP 7470/2 from IGP Chemie GmbH and laminated on both sides with aluminum. Hensotherm 2KS was diluted 1:1 with water and sprayed onto the Basotect, which was then laminated with aluminum foil and dried to constant weight (dry weight of binder 40 g/m.sup.2). In the case of fire-protection adhesive VP 7470/2, this was diluted with water and applied to the aluminum foil with a brush. The foil was laid on the Basotect and dried to constant weight with application of gentle pressure (dry weight of binder 130 g/m.sup.2), In both cases, good, homogeneous adhesion of the aluminum foil to the surface of the foam was achieved.

(29) BSK 10300 is a solvent-free, non-flammable, single-component water glass adhesive. The A1 adhesive according to DIN 4102-1 consists of a preparation of aqueous alkali metal silicates to which are added inorganic fillers and also additives to improve the rheological properties and separation behavior.

(30) VP7470/2 is a solvent-free, single-component product that can be used in preventive fire protection as a fire-protection adhesive/coating for various materials. VP7470/2 consists of an aqueous plastic dispersion with inorganic additives and water-releasing (halogen-free) flame retardants.

(31) Hensotherm 2KS Indoor is a fire-protection coating for wood that forms an insulating layer, which enables wood and wood materials to be classified as class B1 building materials in accordance with DIN 4102-1.

(32) Another series of tests investigated the influence of the adhesive system on fire behavior. This was done by producing three different systems based on aluminum foil, Basotect, and binding system and then determining the oxygen index in accordance with ISO 4589-2, a) The upper side of a Basotect plate was laminated with self-adhesive aluminum foil (thickness 0.08 mm, coated on one side with pressure-sensitive adhesive). Applied to the reverse side was a double-sided adhesive film based on acrylate adhesive. The protective film of the double-sided adhesive film was removed for the subsequent fire test. b) The upper side of a Basotect plate was laminated with self-adhesive aluminum foil (thickness 0.08 mm, coated on one side with pressure-sensitive adhesive). c) The upper side of a Basotect plate was sprayed with fire-protection adhesive 10300 (diluted 1:1 with water). The aluminum foil (thickness 0,08 mm without pressure-sensitive adhesive) was then laid on the still-wet surface and weighed down with a weight without compressing the foam excessively. Application of fire-protection adhesive 10300 at an application rate (dry weight) of 400 g/m.sup.2 achieved good homogeneous adhesion of the aluminum foil to the surface of the Basotect.

(33) The following oxygen indices according to ISO 4589-2 were obtained for the three configurations a) to c):

(34) a) LOI: 20.2%

(35) b) LOI: 27.0%

(36) c) LOI: 30.4%

(37) By using suitable adhesive systems, the oxygen index may be increased and the propensity for combustion thus reduced.

(38) For comparison, impregnations based on magnesium oxide as a particulate filler in combination with various binders were investigated.

(39) Magnifin® H-5 IV from Albemarle is a high-purity magnesium hydroxide that has been subjected to a special chemical surface treatment with an aminopolysiloxane.

(40) The binders Acronal® Plus 2483 and Acronal0 5041 from BASF SE are aqueous dispersions of a styrene-acrylic ester copolymer. The organofunctionalized silanes Geniosil® GF9 and Geniosil® GF95 from Wacker Chemie AG are used as adhesion promoters in plastics modified with fillers. Acrodur® 950 L from BASF SE is an aqueous solution of a modified polycarboxylic acid with a polyhydric alcohol as a crosslinking component and is used for formaldehyde-free bonding of wood fibers, other natural fibers or finely divided inorganic materials. Lupamin® 9050 from BASF SE is a copolymer of vinylformamide and vinylamine. The fire-protection adhesive BSK 10300 from IGP GmbH consists of a preparation of aqueous alkali metal silicates to which are added inorganic fillers and also additives to improve the rheological properties and separation behavior.

(41) Corresponding compositions are reported in table 3 below.

(42) TABLE-US-00004 TABLE 3 C1 C2 C3 C4 C5 C6 C7 C8 Starting materials (g) Magnifin ® H-5 IV 2.50 2.50 2.50 2.50 2.50 2.50 2.50 2.50 Acronal ® Plus 2483 (50%) 0.30 Acronal ® 5041 (52%) 0.30 Geniosil ® GF9 0.30 Geniosil ® GF95 0.30 Emuldur ® 360 A (40%) 0.30 Acrodur ® 950 L (50%) 0.30 Lupamin ® 9050 (18%) 0.30 Fire-protection adhesive BSK10300 (66%) 0.30 Water 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 Basotect ® UL (6 ± 2 g/L) 0.49 0.49 0.48 0.48 0.49 0.49 0.50 0.48 Result after impregnation Mass (g) 2.8 2.9 2.5 2.2 2.9 2.9 2.7 2.9 Density (g/L) 34.6 34.9 31.3 26.9 35.0 34.8 33.1 35.4

(43) The impregnated foams of the comparative examples showed poor binding of the magnesium oxide filler. The filler trickled out of the foam almost completely during the mechanical testing described above.