FLAME RETARDANT INSULATION FOR INTERNAL COMBUSTION ENGINES

Abstract

The invention relates to a process for producing polyurethane foam for the thermal and acoustic insulation of engines, wherein the polyurethane foam is obtained or is obtainable by reaction of diisocyanates and/or polyisocyanates with filler-containing polyols, where the filler is preferably a reaction product of diisocyanates and/or polyisocyanates with compounds having hydrogen atoms which are reactive toward isocyanates, in the presence of water and/or physical blowing agents. The invention further relates to the use of the polyurethane foam for thermal and acoustic insulation for internal combustion engines, and also thermal and acoustic insulation for internal combustion engines containing the polyurethane foam.

Claims

1. A process for producing polyurethane foam for the thermal and acoustic insulation of engines, wherein the polyurethane foam is obtained by reaction of a composition comprising a component A1 comprising at least one filled polyol, a component A2 comprising a compound which is reactive toward isocyanates and having a number average molecular weight of from 400 to 18000 g/mol, optionally a component A3 comprising a compound which is reactive toward isocyanates and having a number average molecular weight of from 62 to 399 g/mol, wherein the components A2 and A3 do not contain any filled polyols, a component A4 comprising water and/or at least one physical blowing agent, optionally a component A5 comprising an auxiliary component, an additive, or a combination thereof, and a component B comprising a diisocyanate and/or a polyisocyanate, wherein no styrene-acrylonitrile-filled polyols are present in the composition and the reaction is carried out at an index of from 90 to 110.

2. The process as claimed in claim 1, wherein the at least one filled polyol of the component A1 comprises a filler composition comprising a polyurea dispersion which is obtained by reaction of a diisocyanate and/or a polyisocyanate with a diamine and/or a polyamine having primary and/or secondary amino groups and/or a hydrazine in a polyol component and/or a dispersion which contains urethane groups and is obtainable by reaction of an alkanolamine with a diisocyanate and/or a polyisocyanate in a polyol component.

3. The process as claimed in claim 1, wherein the component A1 comprises from 5 to 35% by weight, based on the component A1, of a filler composition.

4. The process as claimed in claim 1, wherein the at least one filled polyol of the component A1 has a number average molecular weight in the range from 3000 to 5000 g/mol.

5. The process as claimed in claim 1, wherein the at least one filled polyol of the component A1 has an OH number in accordance with DIN 53240 in the range from 10 to 40.

6. The process as claimed in claim 1, wherein the compound of the component A2 has an OH number in accordance with DIN 53240 in the range from 10 to 40.

7. The process as claimed in claim 1, wherein the component B comprises at least one of diphenylmethane 4,4-diisocyanate, diphenylmethane 2,4-diisocyanate, diphenylmethane 2,2-diisocyanate, polyphenylpolymethylene polyisocyanate (multi-ring MDI), and mixtures thereof.

8. The process as claimed in claim 1, wherein the composition does not contain any flame retardants.

9. The process as claimed in claim 1, wherein the composition comprises from 10.0 to 98.9% by weight of the component A1, from 1.0 to 88.9% by weight of the component A2, optionally from 0 to 5% by weight of the component A3, from 0.1 to 10.0% by weight of the component A4, optionally from 0 to 20.0% by weight of the component A5, wherein the parts by weight of the components A1 to A5 add up to 100%.

10. A polyurethane foam for the thermal and acoustic insulation of engines obtained by a process as claimed in claim 1.

11. The polyurethane foam as claimed in claim 10, wherein the polyurethane foam has a foam density in accordance with DIN EN ISO 845 in the range from 100 to 250 kg/m.sup.3.

12. An internal combustion engine, comprising the polyurethane foam of claim 10 applied to an outer surface of the internal combustion engine.

13. An insulation of engines comprising a polyurethane foam as claimed in claim 10.

14. A process for producing insulation as claimed in claim 13, comprising the following steps a) providing a composition as claimed in claim 1 and mixing of the components to give a mixture, b) applying the mixture directly to at least part of an outer surface of an internal combustion engine, c) allowing the mixture to react.

15. The process as claimed in claim 14, wherein the outer surface of the internal combustion engine comprises an engine block, a valve cover, a crankshaft housing, a camshaft housing and/or an air intake.

Description

EXAMPLES

[0182] Polyurethane foams were produced using the following components: [0183] A1 Desmophen 7619 W, a filler-containing polyol comprising 21.6% of polyurea dispersion (PUD) as filler and 78.4% of a polyethylene oxide-polypropylene oxide polyether based on glycerol and having a number average molecular weight of 4007 g/mol and an OH number of 28 [0184] Hyperlite Polyol 1650, a filler-containing polyol comprising 43% of styrene-acrylonitrile (SAN) as filler and 57% of a polyethylene oxide-polypropylene oxide polyether based on glycerol and having a number average molecular weight of 8332 g/mol and an OH number of 20 [0185] A2 Desmophen 10 WF 22 consisting of a polyethylene oxide-polypropylene oxide polyether based on glycerol and having a number average molecular weight of 4500 g/mol and an OH number of 28 [0186] A2 Desmophen 41 WB01 consisting of a polyethylene oxide-polypropylene oxide polyether based on glycerol and having a proportion of more than 70% of ethylene oxide and having a number average molecular weight of 4548 g/mol and an OH number of 37 [0187] A2 Desmophen 10 WF 15 consisting of a polyethylene oxide-polypropylene oxide polyether based on glycerol and having a number average molecular weight of 4007 g/mol and an OH number of 35 [0188] A3 Triethanolamine having a number average molecular weight of 149 g/mol and an OH number of 1128 [0189] A4 Water [0190] A5 Urea [0191] A5 Dabco 33 LV consisting of 33% of 1,4-diazabicyclo[2.2.2]octane dissolved in 67% of dipropylene glycol [0192] A5 Tegostab B 8715 LF 2 consisting of a mixture of modified polyether siloxanes [0193] A5 Isopur Black Paste consisting of a polyol-carbon black mixture containing about 15% of carbon black.

[0194] The isocyanates of the component B have the following compositions:

TABLE-US-00001 TABLE 1 DESMODUR 85/25 DESMODUR 44 V 20 L 2,2-MDI % 3.0 0.1 2,4-MDI % 23.0 3.3 4,4-MDI % 59.0 36.6 Multi-ring MDI % 15.0 60.0 NCO content % 32.6 31.4

[0195] Polyurethane foams were produced by the following process:

[0196] The components A1 to A6 were weighed into a beaker having a volume of 1.851 and mixed by means of a stirrer for 15 s at 4200 rpm. The isocyanate of the component B was weighed out and added and the mixture was stirred at the same speed for a further 5 s.

[0197] The mixture was transferred into a heated aluminum mold (about 50 C., volume: Examples 1-3 and 6-11: 5 l, example 4: 2.8 l) and removed from the mold again after a curing time of 7.5 minutes.

[0198] The foam density was determined in accordance with DIN EN ISO 845 on a test specimen from the core of the molding.

[0199] The compressive strength CV 40 was determined in accordance with DIN EN ISO 3386-1-98.

[0200] Carrying out a burning test in accordance with FMVSS 302 or directive 95/28/EC:

[0201] In the experimental setup, a combustion chamber having the dimensions 706640 cm and ventilation possibility was equipped with a Bunsen burner on a movable rail. A sample holder for a horizontal test specimen having the dimensions 1509013 mm is introduced into the chamber in such a way that a 38 mm long flame of the Bunsen burner can reach precisely to an edge of the test specimen.

[0202] The sample or the sample holder are marked at 25 mm and 125 mm. After lighting the Bunsen burner, same is brought on the rail to the edge of the test specimen and left there for 15 s. The Bunsen burner is then moved back to the starting position at which there is no contact between the flame and the test specimen.

[0203] The spread of the flame is then observed and the time from when the 25 mm mark is exceeded until self-extinguishing occurs or until the 125 mm mark is reached is determined. The burning speed in mm/min is calculated therefrom.

[0204] As further observation, the dripping behavior is noted. Here, it is relevant whether the foam drips and, if so, whether these drops themselves burn or do not burn.

[0205] The requirements for the engine space are satisfied when the burning speed does not exceed 0 mm/min. For this purpose, the first measurement mark at 25 mm must not be reached by the flame. Non-burning dripping is a further desirable criterion.

[0206] The composition of the polyurethane foams is indicated in tables 2 and 3 below. The weights reported are in each case in % by weight.

TABLE-US-00002 TABLE 2 According to the invention Comparison Example 1 2 3 4 5 6 7 8 9 A1 DESMOPHEN 7619 W 48.85 53.71 24.40 48.88 15.02 15.02 43.96 43.96 (PUD polyol) Hyperlite polyol 1650 24.37 27.99 27.99 (SAN-filled polyol) A2 DESMOPHEN 10WF22 43.99 A2 DESMOPHEN 41WB01 2.93 2.93 2.93 2.93 2.92 2.93 2.93 2.93 2.93 A2 DESMOPHEN 10WF15 43.97 39.06 68.31 68.23 49.65 49.65 48.84 48.84 A3 Triethanolamine 1.22 1.22 1.22 1.22 1.22 1.22 1.22 1.22 1.22 A4 Water 1.30 1.35 1.42 1.20 1.54 1.46 1.35 1.32 1.32 A5 Tegostab B8715LF2 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.24 A5 ISOPUR BLACK 0.49 0.49 0.49 0.49 0.49 0.49 0.49 0.49 0.49 PASTE N A5 Urea 0.80 0.80 0.80 0.80 0.80 0.80 0.80 0.80 0.80 A5 Dabco 33LV 0.20 0.20 0.20 0.24 0.19 0.20 0.20 0.20 0.20 B DESMODUR44 V 20 L 25.05 25.16 25.33 18.68 24.97 17.27 24.67 17.54 30.06 B DESMODUR 85/25 8.35 8.39 8.44 12.45 8.32 5.76 8.22 5.85 10.02 Index (100 NCO/OH) 100 100 100 100 100 70 100 70 120 Mixing ratio to 100 pbw 33.4 33.5 33.8 31.1 33.3 23.0 32.9 23.4 40.1 of polyol: Iso Foam density [kg/m.sup.3] 153 149 144 148 154 168 158 173 146 DIN EN ISO 845 Compressive strength, CV40 64 54 44 44 60 44 76 40 76 [kPa] DIN EN ISO 3386-1-98 Mark at 25 mm not reached and Yes Yes Yes Yes No Yes Yes Yes Yes thus burning rate of 0 mm/min, Mark at 25 mm reached and Yes burning rate is < 100 mm/min Non-burning dripping [yes/no] Yes Yes yes Yes No No No No No (non- (no (no (no (burning (burning (burning (burning (burning burning dripping) dripping) dripping) drops) drops) drops) drops) drops) drops)

TABLE-US-00003 TABLE 3 According to Comparison the invention Example 10 11 12 A1 DESMOPHEN 7619 W 27.99 43.96 43.96 (PUD polyol) Hyperlite polyol 1650 15.02 (SAN-filled polyol) A2 DESMOPHEN 10WF15 49.65 48.84 48.84 DESMOPHEN 41WB01 2.93 2.93 2.93 A3 Triethanolamine 1.22 1.22 1.22 A4 Water 1.46 1.32 1.32 A5 Tegostab B8715LF2 0.24 0.24 0.24 A5 ISOPUR BLACK PASTE 0.49 0.49 0.49 N A5 Urea 0.80 0.80 0.80 A5 Dabco 33LV 0.20 0.20 0.20 B DESMODUR44V20L 27.13 22.55 27.56 B DESMODUR 85/25 9.04 7.52 9.19 Index (100 NCO/OH) 110 90 110 Mixing ratio to 36.2 30.1 36.7 100 pbw polyol:Iso Foam density [DIN 164 157 142 EN ISO 845] Compressive strength, 105 50 59 CV40 [DIN EN ISO 3386] Mark at 25 mm not No Yes Yes reached and thus burning speed is 0 mm/min Mark at 25 mm reached Yes and burning speed is <100 mm/min non-burning dripping No Yes Yes (burning (non-burning (no drops) drops) dripping)

[0207] In the case of the polyurethane foams of comparative examples 6 and 8, which were produced at an index of 70, a higher foam density was necessary for the aluminum mold to be completely filled after complete expansion of the composition for producing the foam. In the case of polyurethane foam of comparative examples 9 and 12, on the other hand, the foam density had to be reduced somewhat since otherwise the pressure in the mold becomes too high.

[0208] The experimental data for examples 1 to 4 and also 11 and 12 according to the invention show that the polyurethane foams of the invention satisfy the flame protection requirements necessary for use in the engine compartment, or on the engine. For none of these foams did the burning speed exceed the threshold of 0 mm/min and the first measurement mark at 25 mm was also not reached for any of these foams. In addition, the burning tests demonstrate that none of the foams according to the invention form burning drops on combustion. The foams according to the invention of examples 2 to 4 and 12 even do not form any drops at all during combustion.

[0209] In comparison thereto, burning drops were formed during combustion of the foam of comparative example 5. This foam also did not satisfy the requirements for burning speed. A styrene-acrylonitrile-filled polyol was used as filled polyol in comparative example 5, while a polyurea-dispersed polyol was used as filled polyol in the examples according to the invention. The comparison of the examples according to the invention with comparative example 5 unambiguously shows that the use of a polyol filled with polyurea dispersion leads to improved fire protection properties compared to the use of a styrene-acrylonitrile-filled polyol. The comparison of example 3 according to the invention with comparative example 5, in particular, shows that the technical effect is unambiguously attributable to the type of filled polyol used. These two examples differ only in respect of the type of filled polyol which was used.

[0210] Comparative examples 6, 7 and 10 show that a mixture of different filled polyols does not lead to the desired technical effect. The polyurethane foams of comparative examples 6, 7 and 10 contain both a polyurea-dispersed polyol and a styrene-acrylonitrile-filled polyol and both formed burning drops during combustion.

[0211] Comparative examples 8 and 9 show that the index at which the polyurethane foams are produced also has effects on the burning behavior of the foams. The foam of comparative example 8 was synthesized at an index of 70 and the foam of comparative example 9 at an index of 120. Both foams contained a polyurea-dispersed polyol as filled polyol and formed burning drops during combustion.