ISOCYANATE-BASED TEMPERATURE-RESISTANT FOAMS WITH HIGH FLAME RESISTANCE

Abstract

The invention relates to temperature-resistant foams with a high degree of flame resistance, to the production of same from aromatic isocyanates and polyepoxides using incorporable catalysts and with formic acid as a blowing agent, and to the use of said foams.

Claims

1.-13. (canceled)

14. A process for producing a foam in which a) a polyisocyanate is mixed with b) at least one organic compound having at least two epoxy groups, c) at least one catalyst accelerating the isocyanate/epoxide reaction, d) chemical and/or physical blowing agents containing formic acid, and e) optionally auxiliary agents and additives, to form a reaction mixture, wherein the equivalent ratio of isocyanate groups to epoxy groups is from 1.2:1 to 500:1, and the reaction mixture is reacted into a foam, wherein said catalyst (c) accelerating the isocyanate/epoxide reaction includes at least one catalyst selected from the group consisting of bisdimethylaminopropylurea, bis(N,N-dimethylaminoethoxyethyl)carbamate, dimethylaminopropylurea, N,N,N-trimethyl-N-hydroxyethylbis(aminopropyl ether), N,N,N-trimethyl-N-hydroxyethylbis(aminoethyl ether), diethylethanolamine, bis(N,N-dimethyl-3-aminopropyl)amine, dimethylaminopropylamine, 3-dimethylaminopropyl-N,N-dimethylpropane-1,3-diamine, dimethyl-2-(2-aminoethoxyethanol) and (1,3-bis(dimethylamino)propane-2-ol), N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, bis(dimethylaminopropyl)-2-hydroxyethylamine, N,N,N-trimethyl-N-(3-aminopropyl)bis(aminoethyl ether), 3-dimethylaminoisopropyl-diisopropanolamine, and mixtures thereof.

15. The process for producing a foam according to claim 14, wherein said isocyanates a) include 2,2-MDI or 2,4-MDI or 4,4-MDI, or oligomeric MDI, or mixtures of two or three of said diphenylmethane diisocyanates 2,2-MDI, 2,4-MDI and 4,4-MDI, or raw MDI, or mixtures of at least one oligomer of MDI and at least one of said low molecular weight MDI derivatives 2,2-MDI, 2,4-MDI or 4,4-MDI.

16. The process for producing a foam according to claim 15, wherein said isocyanates a) include mixtures of at least one oligomer of MDI and at least one of said low molecular weight MDI derivatives 2,2-MDI, 2,4-MDI or 4,4-MDI.

17. The process for producing a foam according to claim 16, wherein the content of said oligomeric MDI is greater than 60% by weight, based on the total weight of component (a).

18. The process for producing a foam according to claim 14, wherein said organic compounds having at least two epoxy groups are selected from the group consisting of a polyglycidyl ether of bisphenol A, bisphenol F, or novolacs, or mixtures thereof.

19. The process for producing a foam according to claim 14, wherein said catalyst accelerating the isocyanate/epoxide reaction (c) includes at least one further amine catalyst in addition to the catalyst having at least one isocyanate-reactive hydrogen atom.

20. The process for producing a foam according to claim 19, wherein said further amine catalyst is selected from the group consisting of boron trichloride tert. amine adducts, N,N-dimethylbenzylamine, N,N-methyldibenzylamine, and mixtures thereof.

21. The process for producing a foam according to claim 14, wherein said catalyst (c) is employed in an amount of from 2.1 to 5% by weight, based on the total weight of components (a), (b) and (c).

22. The process for producing a foam according to claim 14, wherein said blowing agents (d) do not contain any halogenated hydrocarbons.

23. The process for producing a foam according to claim 14, wherein said additive e) includes compounds e1-ii) with at least two isocyanate-reactive hydrogen atoms and a molecular weight of less than 500 g/mol, wherein at least one of said isocyanate-reactive hydrogen atoms belongs to a primary or secondary amino group.

24. A foam obtainable by a process according to claim 14.

25. A method comprising utilizing the foam according to claim 24 as a filling foam for hollow spaces, as a filling foam for electric insulation, as a core of sandwich constructions, for the preparation of construction materials for all kinds of interior and exterior applications, for the preparation of construction materials for vehicle, ship, airplane and rocket construction, for the preparation of airplane interior and exterior construction parts, for the preparation of all kinds of insulation materials, for the preparation of insulation plates, tube and container insulations, for the preparation of sound-absorbing materials, for use in engine compartments, for the preparation of grinding wheels, and for the preparation of high-temperature insulations and hardly flammable insulations.

26. A method comprising utilizing the foamable mixture according to claim 14 before the end of the foaming to form the foam having high temperature resistance according to the invention for adhesively bonding substrates, for adhesively bonding steel, aluminum and copper plates, plastic sheets, and polybutylene terephthalate sheets.

Description

EXAMPLES

[0065] In the following Examples, all percentages are by weight.

[0066] Unless explicitly stated otherwise, all quantities and measured values relate to foams prepared without subsequent storage at elevated temperature (annealing).

[0067] The measurement of the compressive strengths was effected according to ISO 844 EN.

[0068] The measurement of the bulk densities was effected according to DIN EN ISO 845.

[0069] The thermal conductivity was determined according to DIN 52612-2 at a temperature of 10 C.

[0070] The measurement of the maximum average rate of heat emission (MARHE) was effected according to ISO 5660-1. The measurement of the total smoke production per occupied surface (TSP) was effected according to ISO 5660-2. All tests were performed with a radiant heat flux density of 50 kW/m.sup.2 on test specimens having dimensions of 100 mm100 mm20 mm.

[0071] The flammability and flame spread were determined according to the requirements of building material class B2 according to DIN 4102-1.

[0072] The setting time is defined as the period between the beginning of stirring and the time when no more adhesive effect can be observed when the foam surface is touched with a rod.

[0073] All Examples according to the invention were prepared with a total amount of starting materials of 50010 g. The foams were foamed in cardboard cups with volumes of 10 liters.

[0074] The following starting materials were used:

[0075] Isocyanates:

[0076] A0: Mixture of 60% by weight 2,4-diisocyanatodiphenylmethane and 40% by weight 4,4-diisocyanatodiphenylmethane.

[0077] A1: Mixture of about 40% by weight monomeric MDI and about 60% by weight oligomeric MDI, average functionality about 2.7, isocyanate content of 31.5 g/100 g according to ASTM D 5199-96 A and a viscosity at 25 C. of 210 mPa.Math.s according to DIN 53 018.

[0078] A2: Mixture of about 30% by weight monomeric MDI and 70% by weight oligomeric MDI, functionality of about 2.8, isocyanate content of 31.5 g/100 g according to ASTM D 5199-96 A, viscosity at 25 C. of 550 mPa.Math.s according to DIN 53 018.

[0079] A3: Mixture of about 25% by weight monomeric MDI and 75% by weight oligomeric MDI, average functionality of about 2.9, isocyanate content of 31 g/100 g according to ASTM D 5199-96 A, viscosity at 25 C. of 2200 mPa.Math.s according to DIN 53 018.

[0080] A4: For the preparation of A4, A2 was charged, and the lowest boiling components, the isomers of diisocyanatodiphenylmethane, were evaporated by means of a short-path evaporator with a surface area of 0.06 m.sup.2 under a pressure of 0.05 mbar and an oil bath temperature of 175 C. Under such conditions, the mass balance showed that 25 to 27% by weight of the supplied amount was evaporated.

[0081] The thus obtained bottoms product A4 was analyzed by means of HPLC, in which an average molecular weight of 527 g/mol and a polydispersity of 1.7 were determined. Further, a content of monomeric MDI of 12% by weight was determined. The viscosity of the product obtained was determined with a plate-plate rheometer with diameters of the plate of 25 mm, and it was 8000 mPa.Math.s at a temperature of 25 C. The distillation product was employed without further purification steps.

[0082] A5: Mixture of about 35% by weight monomeric MDI and 65% by weight polymeric MDI, functionality of about f=3.19, isocyanate content of 30.5 to 32%, viscosity at 25 C. from 610 to 750 mPa.Math.s according to DIN 53 019.

[0083] Epoxides:

[0084] B0: Diglycidyl ether of bisphenol A, Ruetapox 0162, commercial product of Bakelite AG; Duisburg/Germany, epoxide index: 5.8-6.1 eq/kg and an epoxy equivalent of 167-171 g/eq, viscosity at 25 C. is 4000 to 5000 mPas.

[0085] B1: diglycidylether of bisphenol A, commercial product D.E.R. 332 von The Dow Chemical Company, USA, epoxy equivalent of 171-175 g/eq according to ASTM D-1652, viscosity at 25 C. is 4000 to 6000 mPa.Math.s according to ASTM D-445.

[0086] B2: Leuna Epilox A 18-00, low molecular weight epoxy resin based on bisphenol A, commercial product of LEUNA-Harze GmbH, Leuna/Germany, epoxy equivalent of 175-185 g/eq according to DIN 16 945, viscosity at 25 C. from 8000 to 10,000 mPa.Math.s according to DIN 53 015.

[0087] B3: Leuna Epilox F 16-01, low molecular weight epoxy resin based on bisphenol F, commercial product of LEUNA-Harze GmbH, Leuna/Germany, epoxy equivalent of 157-167 g/eq according to DIN 16 945, viscosity at 25 C. from 1200 to 1600 mPa.Math.s according to DIN 53 015.

[0088] B4: Leuna Epilox F 17-00, low molecular weight epoxy resin based on bisphenol F, commercial product of LEUNA-Harze GmbH, Leuna/Germany, epoxy equivalent of 165-173 g/eq according to DIN 16 945, viscosity at 25 C. from 2500 to 4500 mPa.Math.s according to DIN 53 015.

[0089] C Catalysts

[0090] C0 Addocat 3144: N-[3-(dimethylamino)propyl]formamide, commercial product of Rheinchemie, Mannheim/Germany

[0091] C1 Accelerator DY 9577: boron trichloride-amine complex, thermolatent catalyst, commercial product of Huntsman, Bad Sackingen, Germany

[0092] C2 N,N-Methyldibenzylamine, CAS No. 102-05-06, obtainable from Sigma-Aldrich/Germany

[0093] C3 N,N-Dimethylbenzylamine, 98% CAS No. 103-83-3, obtainable from Sigma-Aldrich/Germany

[0094] C4 Dabco-T: N,N,N-trimethylaminoethylethanolamine, commercial product of Air Products and Chemicals, Allentown Pa., USA

[0095] C5 Jeffcat ZF-10: N,N,N-trimethyl-N-hydroxyethylbis(aminoethyl ether), commercial product of Huntsman, Bad Sackingen, Germany

[0096] C6 Jeffcat ZR-50: N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, commercial product of Huntsman, Bad Sackingen, Germany

[0097] C7 Lupragen N 101: 2-dimethylaminoethanol, commercial product of BASF SE, Ludwigshafen, Germany

[0098] C8 Lupragen N 107: dimethyl-2-(2-aminoethoxy)ethanol, commercial product of BASF SE, Ludwigshafen, Germany

[0099] C9 Dabco TMR-30: 2,4,6-tri(dimethylaminomethyl)phenol catalyst from the company Air Products

[0100] Blowing Agents

[0101] D0 Formic acid (98-100%), CAS No. 64-18-6, obtainable from KMF Laborchemie, Lohmar/Germany

[0102] D1 85% by weight formic acid CAS No. 64-18-6 in water

[0103] D2 Water

[0104] D3 Solkane 365/227: liquid hydrofluorocarbon as a blowing agent for foams, mixture of pentafluorobutane (87% by weight) with heptafluoropropane (13% by weight), obtainable from Solvay Fluor GmbH, Hannover, Germany

[0105] D4 Enovate 3000: liquid hydrofluorocarbon pentafluoropropane as a blowing agent for foams, obtainable from Honeywell International Inc., Buffalo, USA

[0106] D5 Cyclopentane, CAS No. 287-92-3

[0107] D6 Formacel 1100: liquid hydrofluorocarbon hexafluorobutene as a blowing agent for foams, obtainable from DuPont de Nemours (Germany) GmbH, Neu Isenburg, Germany

[0108] D7 Solkane R 141b: 1,1-dichloro-1-fluoroethane

[0109] E Additives

[0110] E1 p-Toluenesulfonic acid methyl ester: CAS No. 80-48-8, obtainable from Merck KGaA Darmstadt/Germany

[0111] E2 Desmophen 3600Z: polyether polyol, OH number 56 mg KOH/g, f=2, prepared by propoxylation of 1,2-propylene glycol: commercial product of Bayer MaterialScience, Leverkusen, Germany

[0112] E3 Tegostab B 8411: polyether polysiloxane, commercial product of Evonik, Essen, Germany

[0113] E4 Tegostab B 8485: polyether polysiloxane, commercial product of Evonik, Essen, Germany

[0114] E5 DETDA 80, diethyltoluenediamine, CAS No. 68479-98-1, obtainable from Lonza, Basel, Switzerland

[0115] E6 Dabco DC 193, silicone surfactant from the company Air Products

Example 1

[0116] (Comparison, EPIC Reaction Resin Preparation, Preliminary Trimerization to Intermediate)

[0117] At 50 C., 800 g of isocyanate A0 was mixed with 200 g of epoxide B0 and 0.1 ml of C3, followed by heating at 120 C. The slightly exothermic reaction indicated the immediate start of the isocyanurate formation. After a reaction time of 2 hours without external heating, the charge was cooled. This resulted in an interior temperature of about 90 C. A sample was taken from the charge. The sample has an NCO content of 23% NCO. The reaction was quenched by adding 1.07 g of E1. Subsequently, the charge was stirred at 120 C. for another 30 min. A clear yellow storage-stable resin that is liquid at 20 C. and has a viscosity at 25 C. of 2080 mPa.Math.s and an NCO content of 21.4% (intermediate) was formed.

Example 2a

Comparison

[0118] By means of a quick stirrer, 400 g of the resin from Example 1 was loaded with air for 2 minutes. With stirring, 17.6 g of E2, 7.0 g of E3 and 3.5 g of C0 are added. Immediately thereafter, 6.0 g of D0 was added, and the reaction mixture was thoroughly mixed for another 10 s. The reaction mixture was cast into a cardboard box having dimensions of 20 cm20 cm24 cm, and the reaction mixture was allowed to foam in said cardboard box. The foam was annealed at 200 C. for 3 hours.

[0119] The bulk density of the thus obtained foam was 39 kg/m.sup.3, the compressive strength was 0.246 N/mm.sup.2. The foam meets the requirements of building material class B2 according to DIN 4102-1. The foam had a MARHE value of 120 kW/m.sup.2 and a total smoke production of 920 m.sup.2/m.sup.2.

Example 2b

Comparison

[0120] By means of a quick stirrer, 400 g of the resin from Example 1 was loaded with air for 2 minutes. With stirring, 17.6 g of E2, 7.0 g of E3 and 3.5 g of C0 are added. Immediately thereafter, 6.0 g of DO was added, and the reaction mixture was thoroughly mixed for another 10 s. The reaction mixture was cast into a cardboard box having dimensions of 202024 cm, and the reaction mixture was allowed to foam in said cardboard box.

[0121] The bulk density of the thus obtained foam was 39 kg/m.sup.3, the compressive strength was 0.296 N/mm.sup.2. The foam does not meet the requirements of building material class B2 according to DIN 4102-1. The foam had a MARHE value of 132 kW/m.sup.2 and a total smoke production of 761 m.sup.2/m.sup.2.

Example 3

[0122] The isocyanate and the epoxy resin were mixed together by means of a quick stirrer at 1000 rpm for 20 s to 30 s. The chemical blowing agent was added and mixed in at 1000 rpm for 10 s. Physical blowing agents were then added and mixed in at 200 rpm until a homogeneous mixture was obtained. Thereafter, catalysts were added and mixed in at 2000 rpm for 3 s.

[0123] The exact composition of the starting substances and the mechanical values and the results of the fire test of the foams obtained are stated in Table 1.

TABLE-US-00001 TABLE 1 Components in foam formulation and physical characteristics. All amounts stated in % by weight. Formulation 3.1 3.2 3.3 3.4 Isocyanate A1 A2 A3 A4 Isocyanate amount 68.2 68.16 68.51 68.16 Epoxy resin B1 B1 B1 B1 Epoxy resin amount 17.65 17.65 17.45 17.65 Catalyst C1 1.02 1.02 1.01 1.02 Catalyst C2 0.73 0.73 0.73 0.73 Catalyst C3 0.49 0.49 0.48 0.49 Catalyst C4 0.64 0.64 0.63 0.64 Blowing agent D1 0.99 0.99 0.98 0.99 Blowing agent D3 7.06 7.06 6.98 7.06 Additive E4 1.93 1.93 1.91 1.93 Additive E5 1.34 1.34 1.33 1.34 Measured values Compressive strength 0.157 0.192 0.187 0.138 (N mm.sup.2) Bulk density (kg m.sup.3) 32 34 35 37 Thermal conductivity 21.5 20.4 20.7 20.2 (mW m.sup.1 K.sup.1) Meets DIN 4102-1 B2 Yes Yes Yes Yes MARHE (kW m.sup.2) 77 72 72 68 TSP (m.sup.2 m.sup.2) 477 386 818 443

Example 4

[0124] According to the foaming method as described in Example 3, foams based on the epoxy component B4 were prepared. The exact composition of the starting substances and the mechanical values and the results of the fire test are stated in Table 2.

TABLE-US-00002 TABLE 2 Components in foam formulation and physical characteristics. All amounts of the formulation stated in % by weight. Formulation 4.1 4.2 4.3 4.4 Isocyanate A1 A3 A2 A5 Isocyanate amount 68.15 68.15 68.15 68.15 Epoxy resin B4 B4 B4 B4 Epoxy resin amount 17.65 17.65 17.65 17.65 Catalyst C1 1.02 1.02 1.02 1.02 Catalyst C2 0.73 0.73 0.73 0.73 Catalyst C3 0.49 0.49 0.49 0.49 Catalyst C4 0.64 0.64 0.64 0.64 Blowing agent D1 0.99 0.99 0.99 0.99 Blowing agent D3 7.06 7.06 7.06 7.06 Additive E4 1.93 1.93 1.93 1.93 Additive E5 1.34 1.34 1.34 1.34 Measured values Compressive strength 0.12 0.12 0.12 0.16 (N mm.sup.2) Bulk density (kg m.sup.3) 26 29 29 34 Thermal conductivity 21.9 22.3 21.6 21.7 (mW m.sup.1 K.sup.1) Meets DIN 4102-1 B2 Yes Yes Yes Yes MARHE (kW m.sup.2) 69 68 81 66 TSP (m.sup.2 m.sup.2) 250 250 375 386

Example 5

[0125] According to the foaming method as described in Example 3, foams were prepared, in which the blowing agent was varied. In Examples V5.7 and V5.8, no catalyst that can be incorporated was employed. In Example V5.9, a catalyst with a little reactive, aromatic OH group was employed. The exact composition of the starting substances and the mechanical values and the results of the fire test are stated in Table 3.

TABLE-US-00003 TABLE 3 Components in foam formulation and physical characteristics. All amounts of the formulation stated in % by weight. Formulation 5.1 5.2 5.3 5.4 5.5 5.6 V5.7 V5.8 V5.9 Isocyanate A2 A2 A2 A2 A2 A2 A2 A2 A2 Isocyanate amount 68.15 68.15 68.15 68.15 68.15 68.15 68.15 68.15 68.15 Epoxy resin B2 B2 B2 B2 B2 B2 B2 B2 B2 Epoxy resin amount 22.62 17.61 19.47 22.49 20.00 19.47 23.2 20.4 17.0 Catalyst C1 1.30 1.01 1.12 1.30 1.15 1.12 1.34 1.18 Catalyst C2 0.94 0.73 0.81 0.94 0.83 0.81 0.96 0.85 Catalyst C3 0.62 0.49 0.54 0.62 0.55 0.54 0.64 0.56 Catalyst C4 0.81 0.63 0.70 0.81 0.72 0.70 0 0 Catalyst C9 4.4 Blowing agent D1 0 0 0 1.53 0 0 0 0 0.6 Blowing agent D2 1.36 1.06 0.93 0 0.88 0.93 1.4 0.9 Blowing agent D4 0 7.05 4.67 0 0 0 0 0 Blowing agent D5 0 0 0 0 4.00 0 0 4.2 Blowing agent D6 0 0 0 0 0 4.67 0 0 Blowing agent D7 8.0 Additive E4 2.47 1.92 2.13 2.46 2.18 2.13 2.53 2.23 Additive E5 1.72 1.34 1.48 1.71 1.52 1.48 1.76 1.55 Additive E6 1.9 Measured values Compressive 0.131 0.129 0.198 0.198 0.137 0.184 0.141 0.139 strength (N mm.sup.2) Bulk density 28.1 24.4 32.6 36.4 25.2 35 27.9 26.6 42.4 (kg m.sup.3) Thermal 23.3 21.8 27.2 24.2 20.6 20.6 23.1 21.4 conductivity (mW m.sup.1 K.sup.1) Meets DIN 4102-1 Yes Yes Yes Yes Yes Yes Yes Yes Yes B2 MARHE (kW m.sup.2) 75 67 64 74 73 72 93 89 125 TSP (m.sup.2 m.sup.2) 591 318 409 568 330 420 591 352

[0126] The Examples in Table 3 show that the fire properties can be significantly improved by the use of catalysts that can be incorporated according to the invention, while the mechanical properties are otherwise similar. In particular, the MARHE values are clearly reduced for the foams according to the invention.

Example 6

[0127] According to the foaming method as described in Example 3, foams were prepared, in which exclusively reactive catalysts were used in Examples 6.1 to 6.5.

[0128] In comparison, when a catalyst package with non-reactive components (6.6) is used, the setting time of the foam becomes extremely long. Thus, the foam remains adhesive over a very long time and is characterized by too low a strength after foaming, which is very disadvantageous for the processing.

TABLE-US-00004 TABLE 4 Components in foam formulation and physical characteristics. All amounts of the formulation stated in % by weight. Formulation 6.1 6.2 6.3 6.4 6.5 6.6 Isocyanate A2 A2 A2 A2 A2 A2 Isocyanate amount 68.15 68.15 68.15 68.15 68.15 68.15 Epoxy resin B2 B2 B2 B2 B2 B2 Epoxy resin amount 19.89 19.89 19.89 19.89 19.89 20.0 Catalyst C4 0.72 0 0 0 0 0 Catalyst C5 0 0.72 0 0 0 0 Catalyst C6 0 0 0.72 0 0 0 Catalyst C7 0 0 0 0.72 0 0 Catalyst C8 0 0 0 0 0.72 0 Catalyst C1 0 0 0 0 0 0.27 Catalyst C2 0 0 0 0 0 0.14 Catalyst C3 0 0 0 0 0 0.10 Blowing agent D1 1.11 1.11 1.11 1.11 1.11 0.96 Blowing agent D3 7.96 7.96 7.96 7.96 7.96 8.0 Additive E4 2.17 2.17 2.17 2.17 2.17 2.18 Additive E5 0 0 0 0 0 0.21 Measured values Setting time (s) 94 285 230 260 118 >600 s Compressive strength 0.152 0.143 0.139 0.164 0.146 0.17 (N mm.sup.2) Bulk density (kg m.sup.3) 28.8 29.6 29.2 30 28.9 34 Thermal conductivity 21.4 23.4 22.4 22.9 21.8 23.4 (mW m.sup.1 K.sup.1) Meets DIN 4102-1 B2 Yes Yes Yes Yes Yes Yes MARHE (kW m.sup.2) 90 92 88 85 89 85 TSP (m.sup.2 m.sup.2) 375 420 443 375 750 409