HIGH TEMPERATURE-RESISTANT POLYISOCYANURATE FOAMS

Abstract

The present invention relates to a polyisocyanurate foam obtainable by reacting a mixture in the presence of a catalyst and optionally an initiator, comprising or consisting of: A) a polyisocyanate component comprising at least one aliphatic polyisocyanate; B) a component reactive to isocyanate comprising at least one polyol and/or an alcohol and also optionally an amine; C) at least one blowing agent; D) at least one foam stabilizer and E) optionally at least one additive, characterized in that
the mixture, upon accompanying use of an isocyanate-reactive component (polyol, alcohol, amine), has an index of at least 200. The invention further relates to a process for producing such a foam and use thereof as an insulating material, as a construction element, as facade insulation, as reactor insulation, as battery insulation, as superheated steam insulation, as insulation for a still, or as weather-resistant insulating material.

Claims

1.-15. (canceled)

16. A polyisocyanurate foam obtained by reacting a mixture in the presence of a catalyst and optionally an initiator, comprising: A) a polyisocyanate component comprising at least one aliphatic polyisocyanate; B) a component reactive to isocyanate comprising at least one polyol and/or an alcohol and also optionally an amine; C) at least one blowing agent; D) at least one foam stabilizer and E) optionally at least one additive, wherein the mixture has an index of at least 200.

17. The polyisocyanurate foam as claimed in claim 16, wherein the polyisocyanate component A) has a proportion of aliphatic polyisocyanates of at least 50% by weight, based on the polyisocyanate component.

18. The polyisocyanurate foam as claimed in claim 16, wherein the aliphatic polyisocyanate comprises 1,6-hexamethylene diisocyanate and/or 1,5-pentamethylene diisocyanate and/or mixtures of the same and optionally additionally 4,4-methylenediphenyl diisocyanate.

19. The polyisocyanurate foam as claimed in claim 16, wherein the polyisocyanate component A) has a proportion of isocyanate groups of at most 40% by weight, based on the total weight of polyisocyanate component A).

20. The polyisocyanurate foam as claimed in claim 16, wherein the polyisocyanate component A) has an average NCO functionality of 2.0 to 6.0.

21. The polyisocyanurate foam as claimed in claim 16, wherein the polyisocyanate component A) has a viscosity in accordance with DIN EN ISO 3219:1994-10 at 23 C. of 100 to 30 000 mPas.

22. The polyisocyanurate foam as claimed in claim 16, wherein the polyol of the component B) reactive to isocyanate has a molecular weight of less than 200 g/mol.

23. The polyisocyanurate foam as claimed in claim 16, wherein the foam stabilizer D) is selected from silicone surfactants, ethoxylated fatty alcohols and alkylphenols, fatty acid-based amine oxides and betaines, castor oil esters, ricinoleic acid esters or mixtures thereof.

24. The polyisocyanurate foam as claimed in claim 16, wherein the additive E) is selected from flame retardants, emulsifiers, fillers or mixtures thereof.

25. The polyisocyanurate foam as claimed in claim 16, wherein the mixture has an index of 200 to 5000.

26. The polyisocyanurate foam as claimed in claim 16, wherein the mixture comprises 80.0 to 98.0% by weight of polyisocyanate component A), 0.1% to 10% by weight of component B reactive to isocyanate, 1.0 to 10% by weight of blowing agent C), 0.1 to 3.0% by weight of foam stabilizer D), and 0 to 10% by weight of additive(s) E).

27. The polyisocyanurate foam as claimed in claim 16, wherein the polyisocyanurate foam has a relative mass loss of at most 2.0% at 200 C., determined by thermogravimetry in a nitrogen atmosphere in a temperature range from 20 to 200 C. at a heating rate of 20 C./minute, especially a relative mass loss of at most 1.5%.

28. The polyisocyanurate foam as claimed in claim 16, wherein the polyisocyanurate foam is heat treated in a two-stage process after start of reaction at <100 C. of the starting components before mixing followed by the foaming reaction at a temperature of at least 60 C. over a period of at least 1 hour.

29. A process for producing a polyisocyanurate foam in which a mixture is reacted in the presence of a catalyst and optionally an initiator, which comprises the following components: A) a polyisocyanate component comprising at least one aliphatic polyisocyanate; B) a component reactive to isocyanate comprising at least one polyol and/or an alcohol and also optionally an amine; C) at least one blowing agent; D) at least one foam stabilizer and E) optionally at least one additive, wherein the mixture has an index of at least 200.

30. An insulating material, a construction element, a facade insulation, a reactor insulation, a battery insulation, a superheated steam insulation, an insulation for a still, or a weather-resistant insulating material comprising the polyisocyanurate foam as claimed in claim 16.

Description

EXAMPLES

[0088] The present invention will now be more particularly discussed by means of examples:

Determination Methods Used:

[0089] The average NCO functionality of component A) is determined by gel permeation chromatography (GPC) unless stated otherwise. Functionality is an expression for the number of reactive groups per molecule, i.e. for the number of potential linkage points in the formation of a network. Polyisocyanates, which are formed, for example, in the trimerization of diisocyanates, do not consist of only one defined type of molecule, but comprise a wide distribution of different molecules having different functionalities. For polyisocyanates, therefore, the average functionality is specified as parameter. The average functionality of polyisocyanates is unambiguously determined by the ratio of number-average molecular weight and equivalent weight and is generally calculated with the aid of the molecular weight distribution determined by gel permeation chromatography.

[0090] The viscosity of component A is determined in accordance with DIN EN ISO 3219:1994-10 at 23 C. unless stated otherwise.

Components Used:

Trimerization Catalysts:

[0091] DABCO K15: (potassium 2-ethylhexanoate) [0092] Desmorapid: 1792 (potassium acetate) [0093] Sodium methoxide 25% by weight in methanol

Polyol B) Used:

[0094] Glycerol

Foam Stabilizers (Polyether-Polydimethylsiloxane Copolymers):

[0095] Tegostab B8421: [0096] Tegostab B8490 [0097] Tegostab B 84702 LV:

Polyisocyanates A) Used:

[0098] Desmodur N3300: Isocyanurate group-containing polyisocyanate based on 1,6-diisocyanatohexane (HDI) having an NCO content of 21.7%, an average NCO functionality of 3.5 (according to GPC), a content of monomeric HDI of 0.1% and a viscosity of 3000 mPas (23 C.). [0099] Desmodur N3600: Isocyanurate group-containing polyisocyanate based on 1,6-diisocyanatohexane (HDI) having an NCO content of 23.2%, an average NCO functionality of 3.2 (according to GPC), a content of monomeric HDI of 0.2% and a viscosity of 1200 mPas (23 C.). [0100] Desmodur 44 M: 4,4-Methylenediphenyl diisocyanate [0101] Desmodur H: hexamethylene diisocyanate [0102] Desmodur 44V20L: Isocyanate based on diphenylmethane-4,4-diisocyanate (MDI) having an NCO content of 30.5-32.5 and a viscosity of 160-240 mPas (25 C.) [0103] Bayhydur 3100: Hydrophilic isocyanurate group-containing polyisocyanate based on 1,6-diisocyanatohexane (HDI) having an NCO content of 17.4%, an average NCO functionality of 3.2 (according to GPC), a content of monomeric HDI of 0.1% and a viscosity of 2800 mPas (23 C.).

Example 1

[0104] An isocyanate-reactive composition of 3.75 g of glycerol, 0.50 g of formic acid, 4.37 g of water, 2.10 g of foam stabilizer Tegostab B8421 and 3.00 g of Dabco K15 catalyst was mixed with the isocyanate mixture of 200.40 g of Desmodur N3600, 28.63 g of Bayhydur 3100 and 57.26 g of Desmodur H and cast in a mold. The mixture itself was produced using a stirrer at 3730 rpm with 15 seconds mixing time and a raw materials temperature of 23 C. The mold was then placed in an oven at 60 C. The foam had hardened after 2 h.

Example 2

[0105] An isocyanate-reactive composition of 9.90 g of glycerol, 3.71 g of formic acid, 1 g of water, 2.10 g of foam stabilizer Tegostab B8421 and 3.00 g of Desmorapid 1792 catalyst was mixed with the isocyanate mixture of 140.15 g of Desmodur N3600, 140.15 g of Desmodur 44M and cast in a mold. The mold was then placed in an oven at 60 C. The foam had hardened after 12 min. A 2 hour heat treatment at 60 C. followed.

Example 3

[0106] An isocyanate-reactive composition of 0.61 g of glycerol, 2.78 g of foam stabilizer Tegostab B84702 LV, 2.78 g of sodium methoxide 25% dissolved in methanol 75% as catalyst was mixed with an isocyanate-hydrocarbon mixture of 272.12 g of Desmodur N3600 and 21.70 g of hexane and cast in a mold. The isocyanate-hydrocarbon mixture itself was prepared ca. 1 day beforehand using a stirrer at 3750 rpm and 23 C. raw material temperature. The mold was then placed in an oven at 70 C. The foam had hardened after 4 min.

Example 4

[0107] An isocyanate-reactive composition of 15.00 g of glycerol, 2.00 g of foam stabilizer Tegostab B8421, 34.24 g of cobalt naphthenate (6%) catalyst and 2.85 g of dimethyl sulfoxide (Eur. Polym. J., Vol 18, 549ff, 1982) was mixed with an isocyanate-hydrocarbon mixture of 161.84 g of Desmodur N3600 and 69.36 g of Desmodur 44M and 14.70 g of hexane and cast in a mold. The isocyanate-hydrocarbon mixture itself was prepared using a stirrer at 3750 rpm and 23 C. raw material temperature. The mold was then placed in an oven at 60 C. The foam had hardened after 6 min. A 2 hour heat treatment at 60 C. followed.

Example 5a

[0108] An isocyanate-reactive composition of 1.08 g of glycerol, 1.44 g of foam stabilizer Tegostab B84702 LV, 2.88 g of Dabco K15 catalyst, 0.288 g of sodium methoxide 25% dissolved in methanol 75% as catalyst was mixed with an isocyanate-ester mixture of 282.26 g of Desmodur N3600 and 12.06 g of methyl formate and cast in a mold. The isocyanate-hydrocarbon mixture itself was prepared using a stirrer at 3750 rpm and 23 C. raw material temperature. The mold was then placed in an oven at 105 C. The foam had hardened after 38 min. A 2 hour heat treatment at 70 C. followed.

Example 5b

[0109] An isocyanate-reactive composition of 1.08 g of glycerol, 1.44 g of foam stabilizer Tegostab B84702 LV, 2.88 g of Dabco K15 catalyst, 0.288 g of sodium methoxide 25% dissolved in methanol 75% as catalyst was mixed with an isocyanate-ester mixture of 282.26 g of Desmodur N3600 and 12.06 g of methyl formate and cast in a mold. The isocyanate-hydrocarbon mixture itself was prepared using a stirrer at 3750 rpm and 23 C. raw material temperature. The mold was then placed in an oven at 105 C. The foam had hardened after 38 min. A 2 hour heat treatment at 115 C. followed.

Example 6

[0110] An isocyanate-reactive composition of 1.13 g of glycerol, 1.51 g of water, 0.875 g of foam stabilizer Tegostab B8421 and 1.25 g of Desmorapid 1792 catalyst was mixed at 3600 rpm with an isocyanate mixture of 107.79 g of Desmodur 3600, 8.29 g of Desmodur XP2675 and 4.15 g of Bayhydur 3100 and cast in a mold. The mold was then placed in an oven at 80 C. The foam had hardened after 40 min. A two hour heat treatment at 80 C. followed.

Comparative Example 1

[0111] An isocyanate-reactive composition of 72.07 g of Stepanpol PS-2325 (OH number: 240 mg KOH/g, functionality: 2), 13.86 g of TCPP (tris(2-chloroisopropyl) phosphate), 1.85 g of foam stabilizer Tegostab B8421, 2.40 g of Desmorapid 1792, 0.83 g of Jeffcat DMCHA (cyclohexyldimethylamine) and 1.11 g of water was mixed with an isocyanate-hydrocarbon mixture of 194.03 g of Desmodur 44V20L and 13.86 g of c/isopentane (30/70) and cast in a mold. The isocyanate-hydrocarbon mixture itself was prepared using a stirrer at 3750 rpm and 23 C. raw material temperature. The mold was then placed in an oven at 60 C. The foam had hardened after 30 s.

Determination of the Mass Loss on Heating:

[0112] The polyisocyanurate foams obtained according to examples 1 to 5b and comparative example 1 were investigated with respect to their mass loss on heating. The experiments were carried out in a nitrogen atmosphere at a heating rate of 20 C./minute. The mass loss was determined by means of thermogravimetry by comparison with the respective starting mass. It was found that, surprisingly, the polyisocyanurate foams according to the invention have a distinctly improved temperature resistance.

TABLE-US-00001 Starting mass Mass loss at Mass loss at Mass loss at Example Heat treatment loss 200 C. 250 C. 400 C. Example 1 60 C., 2 h 195 C. 0.8% 1.9% 10.5% Example 2 60 C., 2 h 230 C. 0.9% 1.4% 24.0% Example 3 60 C., 2 h 190 C. 0.8% 1.6% 5.6% Example 4 60 C., 2 h 200 C. 0.9% 6.7% 29.0% Example 5a 70 C., 2 h 250 C. 0.8% 1.6% 5.5% Example 5b 115 C., 2 h 250 C. 0.4% 0.6% 3.7% Example 6 80 C., 2 h 245 C. 0.6% 1.1% 6.6% Comparative example 1 135 C. 3.5% 7.0% 40.0%