EP3380540A1

EP3380540A1 - Pur/pir rigid foams made of polyaddition oligoesters

Info

Publication number: EP3380540A1
Application number: EP16800971.0A
Authority: EP
Inventors: Hartmut Nefzger; Torsten Hagen; Klaus Lorenz; Rene Abels
Original assignee: Covestro Deutschland AG
Current assignee: Covestro Intellectual Property GmbH and Co KG
Priority date: 2015-11-26
Filing date: 2016-11-23
Publication date: 2018-10-03
Also published as: KR20180087318A; CN108350143A; US10982039B2; CA3005676A1; WO2017089417A1; US20180334530A1

Abstract

The invention relates to a method for producing PUR/PIR rigid foam materials, having the steps of reacting at least one polyester polyol (a), which can be obtained by reacting a.1.) at least one cyclic carboxylic acid anhydride; a.2.) at least one low-molecular diol with a molecular mass of 62 to 450 Da; and a.3.) at least one alkylene oxide; by esterifying the components a.1.) and a.2.) and subsequently oxalkylating the resulting carboxylic acid half-ester using component a.3.); wherein at least the oxalkylation is carried out using a.4.) at least one amine catalyst in which (the) nitrogen atom(s) is/are part of an aromatic ring system, with (b) at least one polyisocyanate-containing component, (c) at least one propellant, (d) at least one or more catalysts, (e) optionally at least one flameproofing agent and/or other auxiliary agents, and (f) optionally at least one additional compound with at least two groups which are reactive towards isocyanates and which differ from polyester polyol (a). The invention also relates to a PUR/PIR rigid foam material which can be obtained using a method according to the invention, to a composite element comprising the PUR/PIR rigid foam material according to the invention, at least one cover layer selected from concrete, wood, press board, aluminum, copper, steel, stainless steel, paper, non-wovens, and plastic, and multilayer composites or a combination thereof. The invention also relates to the use of the PUR/PIR rigid foam materials according to the invention or the composite element according to the invention for heat damping.

Description

PUR / PIR rigid foams from polyaddition oligoesters

Polyurethane-polyisocyanate (PUR / PIR) rigid foams are typically made by reacting a polyol with an isocyanate component in the presence of a blowing agent. Furthermore, additives such as foam stabilizers and flame retardants can also be added. PUR / PIR hardfacings have excellent thermal stability and fire properties compared to other rigid foams such as PUR rigid foams. The cause of these improved properties is attributed to isocyanurate structural elements. As polyol components of such rigid PUR / PIR foams, short-chain polyester polyols are widely used in the prior art. With regard to the synthesis of these short-chain polyester polyols, two possibilities are basically feasible: On the one hand they can be prepared by polycondensation reaction of low molecular weight polyols, usually diols, with low molecular weight polycarboxylic acids, usually dicarboxylic acids and or polycarboxylic acid equivalents, such as anhydrides or esters with monofunctional alcohols. On the other hand, there is also the possibility of short-chain polyester polyols by polyaddition reaction of alkylene oxides with half-esters, as they can be obtained, for example, by addition of diols to Polycarbonsäureanhydride represent. The variant of polyaddition reactions inherently has a number of advantages. These include, for example, a reaction time which is considerably shorter than the polycondensation reaction, a substantially lower energy input as a result of the even exothermic reaction course and not least a practically quantitative reaction yield, since, for example, no yield-reducing reaction water is split off.

There has therefore been no lack of attempts in the past to use such polyaddition reactions for the preparation of short-chain polyester polyols.

DE 36 21 039 Al describes this procedure and leads to hydroxyl-containing oligoesters having OH numbers of 200 to 600 mg KOH / g by reacting cyclic dicarboxylic anhydrides with polyhydric alcohols and / or dialkanolamines in the MoL ratio. 1: 0.5 to 1.5, preferably 1: 0.7 to 1.2, to the corresponding Dicarbonsäurehalbestern - and / or -halbamiden at temperatures of 50 to 150 ° C, preferably 90 to 130 ° C, and subsequent alkoxylation the carboxyl groups with ethylene oxide and / or propylene oxide using an equivalent ratio of acid groups to alkylene oxides of 1: 0.8 to 1.7, preferably 1: 1.0 to 1.6, at temperatures of 80 to 150 ° C, preferably 90 to 130 ° C, characterized in that the alkoxylation is carried out as catalysts using propoxylation products of ammonia, lower C2-C6 aliphatic diamines and piperazine, in which all the NH functions are propoxylated.

With regard to the catalysts to be used, DE 36 21 039 further states (page 3, line 56) that N-memylimidazole, as an excellent transesterification catalyst, would give products with (undesirably) broad molecular weight distribution, which should be avoided.

Therefore, although the preparation of such, catalyzed with N-methylimidazole polyol is described in a comparative example not according to the invention (Comparative Example 2b, page 7, line 10), but it is not reacted to PUR / PIR foam, since it is taught in the DE 36 21 039 was a product with broadened molecular weight distribution and correspondingly increased viscosity, that is to say that it was obviously unsuitable. However, the research underlying this patent application revealed that the preferred oligoester OH number range was from 100 to 280 mg KOH / g, equivalent equivalent molar masses of 200 to 560 g / mol, using the favored in DE 36 21 039 catalysts is accessible only with great difficulty, since the propoxylation of ammonia, the lower C2-C6 aliphatic diamines and the piperazine their rapidly lose catalytic activity with decreasing OH number.

DE 33 15 381 also describes a process for the preparation of polyester or polyether-polyester polyols, characterized in that polyols, preferably polyether polyols having hydroxyl numbers of 15 to 250 mg KOH / g, with at least one carboxylic acid anhydride, preferably phthalic anhydride, in the presence of N-Memylimidazol, triethylenediamine, triphenylphosphine or mixtures of at least 2 of these compounds, esterified to a carboxylic acid half ester and this then with at least one alkylene oxide, preferably ethylene oxide, is alkoxylated in the presence of N-methylimidazole as a catalyst.

It should be noted, however, that the process disclosed in DE 33 15 381 is suitable for molar ratios of alkylene oxide / carboxyl group of not more than 1.5: 1, preferably 1: 1 (page 8, lines 27 and 28). The aim of the present invention, however, was to widen the state of the art to the effect that as Oligoesterkomponenten for PUR / PIR rigid foams are provided whose dicarboxylic acid units are esterified predominantly with Dialkylenglykolstruktureinheiten to the intermediate half ester structures thus more than 1.5 mol Alkylene oxide are to be added. The possibility of using simple imidazole catalysis or catalysis with imidazole derivatives to bind also true dialkylene glycol structural units to half-ester structures was not recognized in DE 33 15 381. Furthermore, there are no indications that such polyester or polyether-polyester polyols could be used as polyol component in PUR / PIR rigid foams. DE 33 15 381 mentions only in a very general way the preparation of polyurethanes (page 3, line 4) from such products, but does not give any embodiments in this respect and also does not claim the production of polyurethanes in general or PUR-PIR rigid foams in particular.

The skilled person could therefore not conclude from DE 33 15 381 and / or DE 3621 039 that the use of amine catalysts in which the (the) nitrogen atom (s) are part of an aromatic ring system, such as imidazole or Imidazolderivaten as a catalyst the production of the desired in the present invention ester structures with Oligoetherbausteinen and in particular their subsequent use as a polyol component in PUR / PIR rigid foams is possible.

It has therefore been an object to provide PUR / PIR rigid foams whose polyol components are cyclic using amine catalysts in which the nitrogen atom (s) are part of an aromatic ring system, such as imidazole or imidazole derivatives Carboxylic acid anhydrides, low molecular weight diols, and alkylene oxides are obtainable, preferably more than 1.5 moles of alkylene oxide per mole of carboxylic acid anhydride are used and the thus obtainable oligoester OH numbers in the range of 100 - have 280 mg KOH / g

Another object was to incorporate the aforementioned polyester components in PUR / PIR rigid foams so that PUR-PIR rigid foams with attractive Properties are obtained whose properties at least the level of analogous, based on conventional Polykondensationspoh / ols PUR / PIR rigid foams reach.

PUR / PIR rigid foams in the context of the present invention are, in particular, those PUR / PIR foams whose density in accordance with DIN EN ISO 845: 2009-10 is in the range from 15 kg / m ³ to 300 kg / m ³ and their compressive strength according to DIN EN 826: 2013 in the range of 0.1 MPa to 5 MPa.

The present invention therefore provides a process for the production of PUR / PIR rigid foams comprising reacting at least one polyester polyol (a) obtainable by reacting a.1.) At least one cyclic carboxylic acid anhydride; a.2.) at least one low molecular weight diol having a molecular weight of 62 to 450 Da; and a.3.) at least one alkylene oxide; by esterification of components a.1.) and a.2.) and subsequent alkoxylation of the resulting carboxylic acid monoester by means of component a.3.); wherein at least the alkoxylation is carried out using a.4.) at least one amine catalyst in which the nitrogen atom (s) is (are) part of an aromatic ring system is carried out with

(b) at least one polyisocyanate-containing component,

(c) at least one propellant,

(d) at least one or more catalysts,

(e) optionally at least one flame retardant and / or other auxiliaries and additives, (F) optionally at least one further compound having at least two isocyanate-reactive groups which are different from the polyester polyol (a).

Further, a PUR / PIR rigid foam, obtainable by a process according to the present invention. In addition, a composite element comprising the PUR / PIR rigid foam according to the present invention and at least one cover layer selected from concrete, wood, pressboard, aluminum, copper, steel, stainless steel, paper, nonwovens and plastic and multilayer composites or a combination thereof.

Also, the present invention relates to the use of the PUR / PIR rigid foams according to the present invention or the composite element of the present invention for thermal insulation.

The parameters described below may preferably be determined according to the measurement methods listed under the heading "Examples." In the present invention, the term "polyols" is also used for the polyesterpolyols (a).

As carboxylic acid anhydrides al) are in principle cyclic aliphatic and aromatic dicarboxylic anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, succinic anhydride, ghitaric, phthalic anhydride and tetrahydrophthalic anhydride into consideration. Preference is given to using maleic anhydride and / or phthalic anhydride and / or ghitaric anhydride, very particularly preferably phthalic anhydride or mixtures of carboxylic anhydrides which consist of at least 85% by weight of phthalic anhydride. Also suitable are mixtures which contain at least 85% by weight of cyclic carboxylic anhydride and at most 15% by weight of one or more dicarboxylic acids, for example succinic, glutaric, adipic, sebacic, phthalic, terephthalic and isophthalic acids, which may also be It is also possible to use mixtures which contain at least 85% by weight of cyclic carboxylic anhydride and at most 15% by weight of one or more anhydrides of monocarboxylic acids, for example acetic anhydride or benzoic anhydride.

Suitable low molecular weight diols a.2.), Which are used for the purpose of ring opening the cyclic anhydrides, are in principle all diols having molecular weights in the range of 62 to 450 Da into consideration, such as ethylene glycol, 1,3-propanediol, 1,2 Propanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, 2-methyl-l, 3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol and 3-methyl-1,5 Pentanediol, which can be used singly or as a mixture.

As low molecular weight diols in the context of the present application are also mixtures with higher functionality alcohols and / or monols selected from the group consisting of glycerol, 1,1,1-trimethylolpropane, pentaerythritol and monols, such as 2-ethyl-l-hexanol, butyldiglycol , Methanol, ethanol, 1-propanol, 2-propanol, n-butanol, 2-butanol, 2-methyl-1-propanol, dodecanol or phenol (derivatives), provided that their proportion is 20% by weight, based on the total the diols used, higher functional alcohols or monols. However, ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol are preferably used, very particularly preferably diethylene glycol.

Carboxylic anhydride a.l.) and low molecular weight diol a.2.) Are in a molar ratio of 1: 0.3 to 1.5, preferably 1: 0.4 to 1.2, more preferably 1: 0.5 to 0.8 to the

corresponding Dicarbonsäurehalbestern implemented, wherein a temperature range of 50 to 150 ° C, preferably 90 to 130 ° C has been found to be suitable.

The preparation of the dicarboxylic acid half esters from carboxylic anhydride a.1.) And low molecular weight diol a.2.) Can be catalyzed or uncatalyzed; preferably no catalyst is used

As alkylene oxides a.3.) For the alkoxylation of the intermediates resulting from the ring opening of the cyclic anhydrides by means of the low molecular weight diols, comprising predominantly half-ester structures, preference is given to 1,2- or 2,3-butylene oxide, Ethylene oxide and propylene oxide, more preferably ethylene oxide or propylene oxide or mixtures of the two epoxides used.

Their addition to the reaction mixture can be continuous. Likewise possible is a block-wise supply of the epoxides or epoxide mixtures, for example by first metering exclusively propylene oxide or a mixture of propylene oxide and ethylene oxide rich in propylene oxide, followed by metering exclusively of ethylene oxide or a mixture of propylene oxide and ethylene oxide rich in ethylene oxide. Preferably, an ethylene oxide content, based on the mass of the metered epoxides, of 90 to 100 wt .-% based on the total weight of the alkylene oxides a.3.), More preferably, it is between 95 and 100 wt .-%.

The alkoxylation is carried out using an equivalent ratio of acid groups to alkylene oxides of, for example, 1: 1.6 to 1: 3.0, preferably 1: 1.7 to 1: 2.5, at temperatures of 80 to 150 ° C, preferably 90 to 140 ° C.

In the process according to the invention, preference is given to using> 1.5 mol of a.3.) Per mol of a.1.). Preferably, (a) has an OH number of 100 to 280 mg KOH / g

Suitable amines for the catalysis of the alkoxylation reaction a.4.) Are amine catalysts in which the nitrogen atom (s) are part of an aromatic ring system. However, particular preference is given to aromatic amines selected from the group of the imidazole and its derivatives, in particular N-methylimidazole

The amine catalyst may be added to the reaction mixture prior to the ring opening of the cyclic carboxylic acid anhydride by means of the low molecular weight diols. But you can also add it only after the ring opening, but before the beginning of the metered addition of the (the) alkylene oxide (s). Suitable catalyst concentrations are preferably in the range from 300 to 7000 ppm, more preferably from 500 to 5000 ppm, particularly preferably from 800 to 3000 ppm, in each case based on the total weight of (a) to (f).

Suitable polyesters (a) preferably have hydroxyl numbers in the range 200 to 600 mg KOH / g, as well as functionalities of 1.3 to 3.5, more preferably 1.6 to 2.2, most preferably 1.8 to 2.1 ,

As polyisocyanate-containing component (b) are in principle aliphatic, cycloaliphatic, araliphatic, heterocyclic and particularly aromatic di- and / or polyisocyanates into consideration, as described by W. Siefken in Justus Liebigs Annalen der Chemie, 562, pages 75 to 136, for example, those of the formula Q (NCO) n, where n = 2 to 4, where n denotes a number average value, and Q is an aliphatic hydrocarbon radical having 2 to 18, preferably 6 to 12 carbon atoms, a cycloaliphatic hydrocarbon radical having 4 to 20 , preferably 5 to 11 C atoms, an aromatic hydrocarbon radical having on average 6 to 27, preferably 6 to 23 C atoms, or an araliphatic hydrocarbon radical having 8 to 15, preferably 8 to 13 C atoms, for. B. such polyisocyanates as described in DE-A 28 32 253, pages 10 to 11, are described. Particularly preferred are the technically readily available polyisocyanates, e.g. The 2,4- and / or 2,6-Tohiylendiisocyanat and any mixtures of these isomers ("TDI"), diphenylmethane diisocyanates ("MDI", 4,4'- and / or 2,4'-, and / or 2 , 2'-isomers), polyphenyl-polymethylene-polyisocyanates, as prepared by aniline-formaldehyde condensation, subsequent phosgenation and optionally distillative concentration of the higher-nuclear components and "modified polyisocyanates" z. Carbodiimide groups, urethane groups, allophanate groups, isocyanurate groups, urea groups and / or biuret groups; in particular those modified polyisocyanates which are derived from 2,4- and / or 2,6-thiylene diisocyanate and preferably from 4,4'- and / or 2,4'-diphenylmethane diisocyanate. Very particular preference is given to polyisocyanates of polyphenylene polymethylene polyisocyanates ("polymer MDI").

Suitable blowing agents (c) in the context of the present invention are both physical and chemical blowing agents. Chemical blowing agents are understood as meaning those compounds which form gaseous compounds by reaction with isocyanates. In contrast, among physical blowing agents such Compounds understood that are present in liquid or gaseous form at 25 ° C, are used and enter into no chemical reaction with the isocyanate.

Physical blowing agents are compounds which are dissolved or emulsified in the starting materials of the polyurethane preparation and which evaporate under the usual reaction conditions, preferably above 25 ° C. Typically, a polyurethane foam according to the invention is heated in the course of the preparation from room temperature up to about 180 ° C. The physical blowing agents are, for example, hydrocarbons, e.g. Cyclopentane, isopentane and n-pentane, butane and propane, halogenated hydrocarbons, and other compounds such as perfluorinated alkanes such as perfluorohexane, perfluorinated alkenes such as 1,1,1,3,3,5,5,5-nonafluoro -4- (trifluoromethyl) pent-2-ene, 1,1,1,3,4,4,5,5,5-nonafluoro-2- (trifluoromethyl) pent-2-ene or cis-1, l, l , 4,4,4-hexafluoro-2-butene, fluorochloroalkenes such as trans-l-chloro-3,3,3-trifluoropropene, and ethers, esters, ketones and / or acetals. Chemical blowing agents are, for example, water and carboxylic acids which release carbon dioxide by reacting with isocyanates to form urea or amide.

As blowing agent component (c) it is preferred to use hydrocarbons and / or water and / or at least one carboxylic acid. More preferred hydrocarbons are hydrocarbons which are gaseous at 25 ° C, most preferred are n-pentane, cyclopentane, iso-pentane and / or mixtures of isomers. These can be used in combination with water and / or carboxylic acids. In alternative embodiments, (c) is water and / or at least one carboxylic acid. The blowing agent component (c) is preferably added in amounts of from 0.1 to 30% by weight, preferably from 0.5 to 20% by weight, particularly preferably from 0.7 to 10% by weight, based on the total weight of the components (a) to (f).

As catalysts (d) for the preparation of the PUR / PIR rigid foams according to the invention, it is possible to use, for example, the known polyurethane or polyisocyanurate formation catalysts, for example organic tin compounds, such as tin diacetate, tin dioctoate, dibutyltin dilaurate and / or strongly basic amines, such as 2,2,2 Diazabicyclooctane, triethylamine, triethylenediamine, Pentamethyldiethylenetriamine, Ν, Ν-dimethylcyclohexylamine or bis (N, N-dimethylaminoethyl) ether, Ν, Ν-dimemylbenzylamine and N-methylimidazole, and for catalysing the PIR reaction, for example, potassium acetate, sodium acetate, sodium N - [(2 hydroxy-5-nonylphenyl) methyl] -N-methylaminoacetate, 2,4,6-tris [(3-dimethylamino) propyl] hexa-hydrotriazine, potassium 2-ethylhexanoate and aliphatic quaternary ammonium salts, eg tetramethylammonium pivalate, and mixtures thereof.

The catalysts (d) are preferably used in amounts of 0.05 to 3 wt .-%, preferably 0.06 to 2 wt .-%, based on the total weight of all components (a) to (f).

The reaction of the abovementioned components is optionally carried out in the presence of flame retardants and / or further auxiliaries and additives (e). As flame retardants, the flame retardants known from the prior art can generally be used. Suitable flame retardants are, for example brominated ethers (eg Ixol ^® B251), brominated alcohols such Dibromneopentylakohol, tri- bromneopentylalkohol and PHT-4-diol, as well as chlorinated phosphates such as tris (2-chloroethyl) phosphate, tris (2-chloroisopropyl) phosphate ( TCPP), tris (1,3-dichloroisoproyl) phosphate, tris (2,3-dibromopropyl) phosphate and tetrakis (2-chloroethyl) ethylenediphosphate. In addition to the aforementioned halogen-substituted phosphates, inorganic flame retardants, such as red phosphorus, red phosphorus-containing preparations, alumina hydrate, antimony trioxide, ammonium polyphosphate and calcium sulfate or cyanuric acid derivatives, such as melamine or mixtures of at least two flame retardants, such as ammonium polyphosphates and melamine and if appropriate, starch for flameproofing of the PUR / PIR rigid foams produced according to the invention can be used. Diethyl ethane phosphonate (DEEP), triethyl phosphate (TEP), dimethylpropyl phosphonate (DMPP), diphenyl cresyl phosphate (DPK) and others can be used as further liquid halogen-free flame retardants.

The flame retardants are in the context of the present invention preferably in an amount of 0 to 30 wt .-%, particularly preferably from 0.3 to 20 wt .-%, in particular from 0.5 to 15 wt .-%, based on the total weight of components (a) to (f) Other auxiliaries and additives are preferably fillers, cell regulators, foam stabilizers, surface-active compounds and / or stabilizers against oxidative, thermal or microbial degradation or aging. Foam stabilizers are substances which promote the formation of a regular cell structure during foaming. The following stabilizers may be mentioned as examples: silicone-based foam stabilizers, such as siloxane-oxyalkylene copolymers and other organopolysiloxanes, furthermore alkoxylation products of fatty alcohols, oxoalcohols, fatty amines, alkylphenols, dialkylphenols, alkylcresols, alkylresorcinol, naphthol, alkylnaphthol, naphthylamine, aniline, alkylaniline, tohiidine, Bisphenol-A, alkylated bisphenol-A, polyvinyl alcohol, and further alkoxylation of condensation products of formaldehyde and alkylphenols, formaldehyde and dialkylphenols, formaldehyde and alkylcresols, formaldehyde and alkylresorcinol, formaldehyde and aniline, formaldehyde and Tohiidin, formaldehyde and naphthol, formaldehyde and alkylnaphthol and formaldehyde and bisphenol-A. Further details on the above and other starting materials are the specialist literature, for example, the Plastics Handbook Volume VE, Polyurethane, Carl Hanser Verlag Munich, Vienna, 1st, 2nd and 3rd Edition 1966, 1983 and 1993, refer. Optionally usable further compounds are compounds (f) having at least two isocyanate-reactive groups, ie having at least two isocyanate-reactive hydrogen atoms, compounds which are generally described below and different from the compounds (a) can be used.

Suitable compounds having at least two isocyanate-reactive groups are, in particular, those which have two or more reactive groups selected from OH groups, SH groups, NH groups, NH ₂ groups and CH-acidic groups, such as, for example, Diketo groups, carry in the molecule. For the preparation of the PUR / PIR rigid foams which are preferably obtainable by the process according to the invention, in particular compounds having 2 to 8 OH groups are used. Preferably used are polyether polyols and / or polyester polyols, which are different from the compounds (a). The hydroxyl number of the polyether polyols and / or polyester polyols used is in the production of PUR / PIR rigid foams preferably 25 to 850 mg KOH / g, more preferably 25 to 480 mg KOH / g, the molecular weights are preferably greater than 230 g / moL Preferably component (f) comprises polyether polyols which are prepared by known processes, for example by anionic polymerization of epoxides, catalyzed by alkali metal hydroxides such as sodium or potassium hydroxide or alkali metal such as sodium, sodium or potassium or potassium isopropoxide, aromatic amines such as N-methylimidazole with the addition of at least one starter molecule bound 2 to 8 reactive hydrogen atoms bound, or by cationic polymerization of epoxides catalyzed by Lewis acids, such as antimony pentachloride, boron fluoride etherate, inter alia, or bleaching earth with the addition of at least one starter molecule 2 to 8 are produced. Furthermore, the production of the polyether polyols can take place by means of double metal cyanide catalysis, in which case a fully continuous procedure is also possible.

Suitable alkylene oxides for this purpose are, for example, 1,2- or 2,3-butylene oxide, ethylene oxide, 1,2-propylene oxide and styrene oxide. Particularly suitable alkylene oxides are those having 2 to 4 carbon atoms in the alkylene radical, in particular ethylene oxide, and 1,2-propylene oxide or 1,2-butylene oxide. The alkylene oxides can be metered individually, in blocks one after the other, in blocks alternating or as mixtures. Suitable starter molecules are, for example, aliphatic polyols and aliphatic and / or aromatic amines and polyamines such as, for example, 1,3-propylene glycol, 1,2-propylene glycol, ethylene glycol, diethylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol , 1,4-butanediol, hexanediol, pentanediol, 3-methyl-l, 5-pentanediol, 1,12-dodecanediol, water, glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol, sucrose, hydroquinone, catechol, resorcinol, bisphenol F, Bisphenol A, 1,3,5-trihydroxybenzene, condensates containing methylol groups from formaldehyde and phenol or melamine or urea, and Mannich bases. Hoclifunctional starter compounds based on hydrogenated starch hydrolysis products can also be used. Such are described for example in EP-A 1 525 244. Examples of amino group-containing starter compounds are ammonia, ethanolamine, diethanolamine, isopropanolamine, diisopropanolamine, ethylenediamine, hexamethylenediamine, aniline, the ishidine of tohiidine, the isomers of Diaminotohiols, the isomers of Diaminodiphenylmethans and in the condensation of aniline with formaldehyde to Diaminodiphenylmethan resulting higher nuclear products , Of course, mixtures of different starter compounds can be used. Further, component (f) may optionally contain polyester polyols, chain extenders and / or crosslinkers. Particularly suitable chain extenders and / or crosslinking agents are di- or trifunctional amines and alcohols, in particular diols and / or triols having molecular weights of less than 400 g / mol, preferably from 60 to 300 g / mol.

To prepare the PUR / PIR rigid foams, the polyisocyanates (b) and the components (a) and, if appropriate, (f) are reacted in amounts such that the isocyanate index of the formulation is> 100, generally from 110 to 600, preferably 150 to 500, particularly preferably 180 to 450.

In this context, the quotient of the amount of substance [mol] of isocyanate groups actually used and the stoichiometrically required molar amount of isocyanate groups for complete conversion of all isocyanate-reactive groups is referred to below the isocyanate index (also called characteristic index or isocyanate index) , multiplied by 100, understood. Since one mole of an isocyanate group is required for the reaction of one mole of an isocyanate-reactive group, the following applies:

Code = (moles isocyanate groups / mole isocyanate-reactive groups) * 100

The PUR / PIR rigid foams can be prepared batchwise or continuously by known methods. The skilled worker is aware, inter alia, the block foam production (continuous and discontinuous), the use in one-component systems (discontinuous) and in Isolierformschaum (discontinuous). The invention described herein relates to all methods. A preferred process is the continuous double-belt process for the production of composite elements comprising PUR / PIR rigid foam cores and one or more cover layers, wherein flexible and / or rigid materials can be used as cover layers. Covering layer materials are, for example, concrete, wood, pressboard, aluminum, copper, steel, stainless steel, paper, nonwovens, in particular mineral nonwovens, and plastic as well as multilayer composites. Preferred plastics are acrylonitrile-butadiene-styrene copolymers, polyethylene, polystyrene, polyvinyl chloride and polypropylene. The kind The cover layer is basically not limited; it may be molded parts, structural elements of construction, pipes, housing parts, etc.

In particular, the present invention relates to the production of metal composite elements. Metal composite elements are sandwich composite elements, consisting of at least two outer layers and a core layer lying between them. In particular, metal-foam composite elements consist of at least two metal cover layers and a core layer of a polyurethane / polyisocyanurate (PUR / PIR) rigid foam. Such metal-foam composite elements are well known in the prior art and are also referred to as metal composite elements. Further layers may be provided between the core layer and the cover layers. For example, the cover layers, e.g. with a paint, to be coated.

Examples of the application of such metal composite elements are flat or lined wall elements and profiled roof elements for industrial halls and cold storage as well as for truck bodies, hall doors or transport containers.

The production of these metal composite elements can be continuous or discontinuous. Devices for continuous production are known, for example, from DE 1 609 668 A or DE 1 247 612 A. The PUR / PIR rigid foams according to the invention comprising PUR and preferably rigid PUR / PIR foams preferably have a closed cell content of greater than 90%, more preferably greater than 95%, determined according to DIN EN ISO 4590: 2003 by pressure change (pycnometer). The PUR / PIR rigid foams according to the invention preferably have a bulk density of from 25 g / m ³ to 300 g / m ³ , particularly preferably from 28 g / m ³ to 50 g / m ³

The use of the PUR / PIR rigid foams according to the invention is carried out in particular for thermal insulation, for example of refrigerators, containers or buildings, for example in the form of insulated pipes, sandwich panels, insulating panels or as an insulating layer in refrigerators. In the following, the invention is illustrated by means of examples.

EXAMPLES The invention will be explained in more detail with reference to the following examples. The following analysis methods were used:

Hvdroxvlzahl: The determination of the OH number was carried out according to the regulation of

DIN 53240 (December 1971).

Acid value: according to DIN EN ISO 2114 (June 2002) Thermal conductivity: according to DIN 52616: 1977-11; at a temperature difference of 20 K and a Schaurmoffoffertemperatur of 10 ° C.

Setting time: The setting time ("gel point ta") is determined by entering a

Dip wooden sticks into the reacting mixture and remove again. It characterizes the time from which the mixture hardens. As to the time is indicated, at which for the first time threads between wood stick and reacting mixture can be pulled. The time measurement begins with the mixing of the foam components.

Tack-free time: Shortly after reaching the setting time, use a wooden stick in a short time

Time intervals scanned the foam surface. Starting from the start of the mixing, the tack-free time is reached when the wooden stick effortlessly dissolves from the foam surface without any adhering product.

Density: The densities were determined according to DIN EN ISO 845: 2009-10.

Dimensional stability: The dimensional stability is determined by adding

Room temperature, the exact dimensions of a cuboid specimen, which was stamped from a foam block prepared at least 12 hours previously prepared so that it has a volume of at least 100 cm ³ and no Randzonenverdichtungen are included determined. The specimen obtained in this way is stored for the specified time (Eg 24 hrs.) At elevated temperature (eg 100 ° C), and determined after cooling for 30 minutes to room temperature again its dimensions. Indicate the relative changes in dimensions in percent of their original dimensions. Adhesion: The foam adhesion is determined qualitatively in the laboratory by making the foam in a paper-laid, open-topped wood mold with edge lengths of 20 cm x 20 cm and after 5 minutes, or 24 hours by hand, this paper from the foam. The liability behavior is assessed qualitatively according to the following scale: very good = 1, good = 2, medium = 3, bad = 4 and no liability = 5.

Similarly, in adhesion tests, foam samples are produced on the double conveyor belt, in which case a sheet metal measuring 50 cm × 90 cm is inserted and foamed over.

Viscosity: The dynamic viscosities were measured using the

Rheometers MCR 51 from Anton Paar in accordance with DIN 53019: 2008-09 with a measuring cone CP 50-1, diameter 50 mm, angle 1 ° determined at shear rates of 25, 100, 200 and 500 s ¹ . The polyols according to the invention and not according to the invention show viscosity values independent of the shear rate.

Fire characteristics: BVD test according to Swiss basic test for the determination of the

Inflammability level of building materials of the Association of cantonal fire insurance in the 1988 edition, with the supplements of 1990, 1994,1995 and 2005. (available from Association of cantonal fire insurance, Federal Road 20, 3011 Bern, Switzerland).

Compressive strength / compressive modulus of elasticity: Determined in a compression test according to DIN EN 826: 2013. Depth of impression: Was determined by looking at the not yet fully reacted foam, prepared in an upwardly open wood form with edge lengths 20 cm x 20 cm (see liability) 1.5 minutes, measured from Vennisch the foam components, a weight of 6 kg with a circular bearing surface with a diameter of 2 cm and then the depth of impression in mm after a time of 2.5 and 5 minutes, also measured from mixing the foam components , certainly. The layer thickness of the foam is about 15 cm.

Ouerzugfestigkeit: Determined in the tensile test perpendicular to the top layer according to EN 1607.

Raw materials used Polyester S240P A polyester polyol manufactured by condensation from Covestro

Germany AG based on phthalic anhydride and diethylene glycol having a hydroxyl value of 240 ± 15 mg KOH / g, an acid number of max. 1.80 mg KOH / g and a viscosity of 12000 ± 2500 mPas measured at 25 ° C. Desmophen 2382 polyester polyol from Covestro Deutschland AG with an OHN of about 240 mg KOH / g, prepared by polycondensation.

Desmophen® V657: Reactive trifunctional polyether polyol for the preparation of

Polyurethane products from Covestro Deutschland AG with a hydroxyl number of 255 ± 15 mg KOH / g, an acid number of max. 0.350 mg KOH / g and a viscosity measured at 25 ° C of 265 ±

20 mPas.

Desmophen® T460: Polyfunctional polyether polyol from the company Covestro Deutschland AG based on amine for the production of polyurethane products having a hydroxyl number of 415 ± 20 mg KOH / g and a measured at 25 ° C viscosity of 8000 ± 1500 mPas.

Desmophen® L2830: Bifunctional polyether polyol with predominantly primary

Hydroxyl groups from. Covestro Germany AG having a hydroxyl number of 26 - 30 mg KOH / g and a viscosity at 25 ° C of 790 - 930 mPa s

Levagard PP: trischloroisopropyl phosphate; Flame retardant from the company Lanxess TEP: triethyl phosphate, flame retardant from Lanxess

Additive 1132: Covestro Deutschland AG, containing the reaction product of

Phthalic anhydride and diethylene glycol having an acid number of about 97 mg KOH / g. B8443: Tegostab B8443, stabilizer from Evonik

Additive 19IF00 A: Component acting as co-blowing agent for the production of

PUR / PIR rigid foams from Covestro Deutschland AG with a hydroxyl number of 1440 ± 50 mg KOH / g, an amine value of 290 ± 15 mg KOH / g, an acid number of 142 ± 9 mg KOH / g and a viscosity at 25 ° C of 390 ± 70 mPa s.

Desmorapid 1792: blowing agent from Covestro Deutschland AG; is used for the production of

Polyurethane foam products is used. Desmorapid® 1792 catalyzes the polyisocyanurate reaction.

Activator 726-B Ν, Ν-dimethylcyclohexylamine. Catalyst for the production of

Polyurethanes of the company. Covestro Germany AG. n-pentane n-pentane from Julius Hoesch.

Desmodur® 44V70L: Liquid mixture of diphenylmethane-4,4'-diisocyanate (MDI) with

Isomeric and higher functional homologues with an NCO Gehah in the range of 30.5 to 32.0 wt .-% NCO and a viscosity in the range of 610 to 750 m Pa s at 25 ° C the company. Covestro

Germany AG.

NMI: N-methylimidazole from BASF

N-methyldiethanolamine: Fa. Aldrich

Desmorapid DB: Ν, Ν-dimethylbenzylamine, catalyst (Lanxess AG). Desmophen® 4051 B: An amine-based tetrafunctional polyether polyol for

Preparation of polyurethane products having a hydroxyl number of 450 to 490 mg KOH / g and a measured at 25 ° C viscosity of 4950 to 5850 mPas (Covestro Deutschland AG).

EO: ethylene oxide from Ineos PO: Propylene oxide from Lyondell

Irganox 1076: octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Ciba

Speciahy Chemicals (now BASF)), antioxidant.

ΑΛ Production of Polvesterpolvolen by Polvadditionsreaktionen

Manufacturing instructions Example A-l .:

273.6 g of diethylene glycol (DEG) and 1.8 g of N-methylimidazole (NMI) were placed in a 2 1 laboratory autoclave. After heating to 50 ° C, 580.3 g of phthalic anhydride were added. Oxygen was removed after closing the filling nozzle by filling the apparatus with an absolute pressure of 3.0 bar nitrogen and then releasing the overpressure to atmospheric pressure. At a stirrer speed of 200 U / min. (Crossbar stirrer), the contents of the autoclave was heated to 120 ° C. At the end of the heating phase, a pressure of 2.8 bar (absolute pressure) was established. The stirrer speed was increased to 800 rpm and then 346.1 g of ethylene oxide were metered into the head space of the autoclave over a period of 5.95 hours at a constant metering rate. Towards the end of the metering phase, the reactor pressure reached the maximum value of 5.0 bar (absolute pressure). After a post-reaction time of 4.1 h, a final pressure of 3.9 bar (absolute pressure) was reached. The product was then baked for 1.0 h in vacuo at 120 ° C. After cooling to 80 ° C 0.630 g Irganox ^® were added 1076th The OH number of the product was 250 mg KOH / g and the viscosity at 25 ° C 9805 mPas.

Table 1 shows the formulations of the polyols of the invention AI, A2, Al 1, A13 and A14.

A3V, A4V, A5V, A6V, A7V and A12V are not according to the invention, because the catalysts used for the preparation contain no nitrogen atoms, which are part of an aromatic ring system. A8V, A9V and A10V are not according to the invention because the equivalent ratios of acid groups to alkylene oxides used for the preparation are not in the range from 1: 1.6 to 1: 3.0.

Β.) Production of PUR / PIR rigid foams

PUR / PIR rigid foams were prepared on a lime scale by adding flame retardant, foam stabilizer, catalyst, water and blowing agent to the respective polyol. The isocyanate-reactive composition thus obtained was mixed with the isocyanate and poured into a mold. The mixture itself was made with a stirrer at 4200 rpm and 23 ° C raw material temperature. The exact formulations including the results of corresponding physical examinations are summarized in Table 2.

Table 2; Production of PUR / PIR foams on a laboratory scale and their properties Production

Thus, Table 2 shows that the tasks could be solved. Examples B-2 and B-3 according to the invention achieve the BVD fire class of the industry standard B-1V, with other important parameters such as the apparent density, the Dimensional stability and adhesion behavior at least unchanged or even slightly improved.

Production of PUR / PIR foams on a double conveyor belt system and their properties. The foam thickness was set to 105 mm, as a cover layer aluminum foil was used with a thickness of 50 μπι.

Thus, also Table 3 shows that the tasks could be solved. In particular, Examples B-5, B-6 and B-7 of the present invention achieve the BVD fire class of the industry standard B-4V, but remarkably lower the flame height. Other important parameters such as the thermal conductivity, the compressive strength, the dimensional stability and the adhesion behavior remain at least unchanged, or even slightly improved.

Claims

Ansprflche

A process for producing rigid polyurethane / PIR foams comprising reacting at least one polyester polyol (a) obtainable by reacting a.1.) At least one cyclic carboxylic acid anhydride;

a.2.) at least one low molecular weight diol having a molecular weight of 62 to 450 Da; and

a.3.) at least one alkylene oxide;

by esterification of components a.1.) and a.2.) and subsequent alkoxylation of the resulting carboxylic acid monoester by means of component a.3.);

wherein at least the alkoxylation using

a.4.) at least one amine catalyst in which the (the)

Nitrogen atom (s) is (are) part of an aromatic ring system, with

(b) at least one polyisocyanate-containing component,

(c) at least one propellant,

(d) at least one catalyst,

(e) optionally, at least one flame retardant and / or further auxiliaries and additives,

(f) optionally, at least one further compound having at least two isocyanate-reactive groups other than the polyester polyol (a).

2. The method according to claim 1, characterized in that> 1.5 mol of a.3.) Per mol a.l.) Are used and (a) has an OH number of 100 to 280 mg KOH7 g.

3. Process according to claim 1 or 2, characterized in that the equivalent ratio of a.3.) To al) is 1.6: 1 to 3: 1.

4. The method according to any one of the preceding claims, characterized in that a.4.) Is selected from the group of imidazole and its derivatives, preferably N-methylimidazole.

5. The method according to any one of the preceding claims, characterized in that a.3.) Is selected from ethylene oxide, propylene oxide or mixtures thereof.

A process according to any one of the preceding claims, characterized in that a.l.) is selected from maleic anhydride, itaconic anhydride, citraconic anhydride, succinic anhydride, glutaric anhydride,

Phthalic anhydride and tetrahydrophthalic anhydride or mixtures thereof.

7. The method according to any one of the preceding claims, characterized in that a.2.) Is selected from ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol or mixtures thereof.

8. The method according to any one of the preceding claims, characterized in that (b) is selected from 2,4-; 2,6-diisocyanate; 4,4; 2,4'-diphenylmethane diisocyanate, derivatives of the above and mixtures thereof.

9. The method according to any one of the preceding claims, characterized in that (c) is selected from n-pentane, cyclopentane, iso-pentane, water, carboxylic acids or mixtures thereof.

10. The method according to any one of the preceding claims, characterized in that

(e) is selected from at least one flame retardant, filler, Zeihegier, foam stabilizers, surface-active compounds, stabilizers against oxidative, thermal or microbial degradation or aging or mixtures thereof.

11. The method according to any one of the preceding claims, characterized in that

(f) is selected from at least one polyether polyol, polyester polyol other than (a) and mixtures thereof.

12. The method according to any one of the preceding claims, characterized in that

(a) is contained in an amount of 10 to 24 wt .-%, preferably 12 to 22 wt .-%;

(b) is contained in an amount of 43 to 89 wt .-%, preferably 48 to 83 wt .-%;

(c) contained in an amount of 0.1 to 30 wt .-%, preferably 0.5 to 20 wt .-%;

(d) is contained in an amount of 0.05 to 3 wt .-%, preferably 0.06 to 2 wt .-%;

(e) is contained in an amount of 0.5 to 12 wt .-%, preferably 3 to 9 wt .-%

(F) is contained in an amount of 0.1 to 9 wt .-%, preferably 1.4 to 7.5 wt .-%; wherein components (a) to (f) give 100% by weight.

13. PUR / PIR rigid foam, obtainable by a process according to one of claims 1 to 12.

14. A composite element comprising a PUR / PIR rigid foam according to claim 13 and at least one cover layer selected from concrete, wood, pressboard, Aluminum, copper, steel, stainless steel, paper, nonwovens and plastic as well as multilayer composites or a combination thereof.

15. Use of a PUR / PIR rigid foam according to claim 13 or a composite element according to claim 14 for thermal insulation.