EP3894460A1

EP3894460A1 - Pur-/pir rigid foams containing polyester polyols with reduced functionality

Info

Publication number: EP3894460A1
Application number: EP19816701.7A
Authority: EP
Inventors: Hartmut Nefzger; Bolko Raffel; Marcel Schornstein; Torsten Hagen
Original assignee: Covestro Intellectual Property GmbH and Co KG
Current assignee: Covestro Intellectual Property GmbH and Co KG
Priority date: 2018-12-14
Filing date: 2019-12-10
Publication date: 2021-10-20
Also published as: WO2020120431A1; US20220025103A1

Abstract

The invention relates to a method for preparing polyester polyols containing monools, and to their use, in particular for preparing polyurethane/polyisocyanurate rigid foams (also referred to hereafter as PUR/PIR rigid foams) with improved fire performance.

Description

Rigid PUR / PIR foams containing polyester polyols with reduced functionality

The invention relates to a process for the production of polyester polyols containing monooie and their use, in particular for the production of rigid polyurethane / polyisocyanurate foams (hereinafter also called rigid PUR / PIR foams) with improved fire behavior.

Rigid PUR / PIR foams are mainly produced today based on aromatic polyester polyols, since these have a positive effect on the flame retardancy of the rigid PUR / PIR foams and the thermal conductivity. The raw materials used in the production of the aromatic polyester polyols are primarily phthalic acid, terephthalic acid and isophthalic acid or their anhydrides. In addition to the aromatic polyester polyols, polyether polyols and sometimes also aliphatic polyester polyols are occasionally used to improve the solubility behavior of pentanes compared to the aromatic polyester polyols or to reduce the brittleness of the isocyanurate-containing PUR / PIR rigid foams.

In the area of insulation board production, polyester-based PUR / PIR rigid foams are enjoying increasing demand. A quantitatively significant polyester polyol is made up of technical glutaric acid (mixture of 70 - 80% glutaric acid, also containing adipic acid and / or succinic acid) and ethylene glycol.

It is also known from the prior art to use monofunctional components, e.g. monofunctional acids to be used in the synthesis of the polyester in order to lower the average functionality of the resulting polyester polyols (see, for example, EP 1219653 A [0012] and WO 97/48747). Examples of such monofunctional building blocks are monobasic unsaturated fatty acids, explicitly mentioned only the monofunctional oleic acid. With regard to the functionality of the polyester polyols, it is stated that they should be in the range between 1.8 and 8, preferably> 2.

EP 1 924 356 B1 also discloses producing rigid PUR / PIR foams with polyester films which have functionalities of 1.5-5 and, in addition to polyfunctional alcohols and carboxylic acids, name hydrophobic substances as further starting materials. The hydrophobic substances are water-insoluble substances which contain a non-polar organic radical and have at least one reactive group selected from hydroxy, carboxylic acid, carboxylic acid esters or mixtures thereof. The equivalent weight of the hydrophobic materials is between 130 and 1000 g / mol. For example, fatty acids such as stearic acid, oleic acid, palmitic acid, fauric acid or finoleic acid, as well as fats and Oils such as castor oil, corn oil, sunflower oil, soybean oil, coconut oil, olive oil or tall oil. If polyesters contain hydrophobic substances, the proportion of the hydrophobic substances in the total monomer content of the polyester alcohol is preferably 1 to 30 mol%, particularly preferably 4 to 15 mol%. For the production of the polyesters containing such monofunctional hydrophobic building blocks, however, just as in the prior art, EP 1 942 356 B1 generally only states that they should be prepared by esterification of the starting products.

However, it would also be interesting to lower the functionality of polyester polyols by using monooils. This would broaden the possible raw material base, so that e.g. waste products from other syntheses can also be used.

Even if polyester polyols with number-average hydroxy functionalities (hereinafter: F (OH)), which are between 1.0 and 2.0, are mentioned in the prior art, there has hitherto been no simple process with which the functionalities of polyester polyols containing monool can be set safely and reproducibly. In particular, the Monooie, for example, due to their low boiling point or due to their water vapor volatility, often during a classic esterification reaction, i.e. when applying vacuum, e.g. 200 mbar or also 100 mbar or also 10 mbar, and / or at high temperatures, e.g. 180 to 220 ° C, completely or partially discharged in a non-reproducible manner (see, for example, WO 2010/139395 A), with the result that the functionality of the resulting polyester polyol cannot be set reproducibly.

It was therefore the object of a process for the preparation of polyester polyols containing monooie, in particular polyester polyols containing monooie with number-average hydroxyl functionalities 1.00 <F (OH) <2.00, to be available with which it is possible from the prior art the problems resulting from technology can be overcome and the polyols can be prepared reproducibly.

The object was achieved by a multi-stage process for the preparation of a polyester polyol PES-B with a number-average OH functionality of> 1.00, preferably with a number-average OH functionality of> 1.00 to <2.00, containing the steps a) complete reaction of at least one carboxyl compound selected from the group consisting of i) polyfunctional, preferably difunctional, carboxylic acids and ii) polyfunctional, preferably difunctional, hydroxy-reactive carboxylic acid derivatives selected from the group consisting of carboxylic acid chlorides, carboxylic acid alkyl esters, hydroxy-functional carboxylic acids, factones and carboxylic acid anhydrides with at least one polyol containing 2-8 hydroxyl groups, preferably 2-3 hydroxyl groups, particularly preferably 2 - 2.5 and especially 2 hydroxyl groups, to a polyester polyol PES-A, in which step a) the ratio of the molar amount of hydroxyl groups [n (OH) _a ] to molar amount of carboxyl-equivalent groups [n (carboxy) _a ]: n (OH) _a / n (carboxy) _a > 1 and the theoretically calculated hydroxyl number of the PES-A is derived from the polyester formulation by balancing the hydroxyl end groups n (OH) _{a used} and the carboxyl end groups or carboxyl-equivalent groups used n (carboxy) _a . For example, carboxylic anhydrides having two carboxyl end groups, lactones each having one hydroxyl and one carboxyl end group, and alkyl esters of dicarboxylic acids having two carboxyl end groups are included in the balance sheet. Further details for determining the theoretical hydroxyl number are explained in more detail below.

b) subsequent reaction of the polyester polyol PES-A obtained in step a) with a monofunctional alcohol (monool) to give the PES-B, the ratio of the molar sum of the hydroxyl groups of all of the reactant molecules used in steps a) and b) to the molar sum of the carboxyl-equivalent groups used: n (OH) E _duct / n (Carboxy) E _duct > 1.

For the purposes of this application, “carboxyl end groups”, “carboxyl-equivalent groups” and “carboxy functions” (together with “n (carboxy)”) mean those functional groups of carboxylic acids and carboxylic acid derivatives which are used in an esterification reaction with a hydroxy group can react.

In the first stage a), a polyester polyol PES-A is produced from the carboxy-functional component and the polyol by means of a complete esterification reaction. “Complete esterification reaction” in the sense of this application means that the esterification reaction is only terminated when the acid number of the polyester polyol A <3 mg KOH / g (preferably <1.5 mg KOH / g). The acid number can be determined according to DIN EN ISO 2114 (June 2002).

In a preferred embodiment, the ratio of the starting materials in stage a) is chosen such that the theoretical hydroxyl number corresponds to the desired hydroxyl number of the polyester PES-A when the components are completely esterified. In the esterification reaction in stage a) the procedure is known in such a way that at least the starting materials difunctional organic acid and difunctional alcohol are initially introduced and reacted by heating. Usually the polyester polyols are made without the use of a solvent. The discharge of the water of reaction in the solvent-free variant is preferably supported by applying a negative pressure, in particular towards the end of the esterification. Here pressures from 1 to 500 mbar are used. However, esterification is also possible above 500 mbar. The discharge of the water of reaction can also be supported by passing an inert gas, such as nitrogen or argon. However, the esterification can also be carried out with the addition of a solvent, in particular a water-carrying solvent (azeotropic esterification), such as benzene, toluene or dioxane.

After the esterification reaction is complete, the actual hydroxyl number of the polyester polyol obtained is then determined, e.g. by means of DIN 53240 (December 1971). If there are deviations from the theoretically calculated hydroxyl number as a result of unintentional discharge of diol, the hydroxyl number can be adjusted to the pre-calculated value by adding the same, in a variant at this point subsequent diol by applying an elevated temperature, e.g. is esterified in the range of 160 to 240 ° C over a longer period of 12 to 4 hours, for example 170 ° C and 10 hours or 180 ° C and 6 hours or 200 ° C and 5 hours without applying a vacuum, so that with respect to the Oligomer distribution there is a Schulz-Flory distribution. If the deviation was very large, the hydroxyl number and also the acid number and further addition of diol can be determined again until the measured hydroxyl number of the PES-A corresponds to the desired hydroxyl number.

The theoretically calculated hydroxyl number of the PES-A is determined from the polyester formulation by balancing the hydroxyl end groups n (OH) _{a used} and the carboxyl end groups or carboxyl-equivalent groups n (carboxy) _{a used} , as defined above. For example, carboxylic anhydrides having two carboxyl end groups, lactones each having one hydroxyl and one carboxyl end group, and alkyl esters of dicarboxylic acids having two carboxyl end groups are included in the balance sheet.

Then the moles of carboxyl end groups (possibly the carboxyl-equivalent groups) are subtracted from the moles of the excess hydroxyl groups used [n (OH) _a - n (carboxy) _a ], so that the number of moles lacking in this way Reactants receives unreactable hydroxyl groups. The difference between (excess) hydroxyl groups and (deficient) carboxyl end groups (in the above sense) gives the number of hydroxyl end groups remaining in the finished polyester polyol: II (OH) PES _A = n (OH) _a - n (carboxy) _a

If the mass of condensate separated off by distillation, for example two moles of water per mole of dicarboxylic acid used, is also taken into account, the mass of the polyester _{polyol batch} and thus also the mole number of hydroxyl end groups, standardized to 1 kg of product, n (OH) _pE s _A / kg. Since the hydroxyl end groups are equivalent to KOH, the theoretical hydroxyl number [g KOH / kg] is obtained by multiplying the number of moles of hydroxyl end groups [mol / kg] standardized to 1 kg product by 56.1 g KOH / mol: hydroxyl number = n (OH) _pE s A / kg * 56.1 g KOH / mol.

The hydroxyl number of the polyester PES-B can then be read out in an analogous manner

n (OH) pEs-B = n (OH) _educt - n (carboxy) _educt

to calculate.

The carboxyl compounds used in step a) are selected from the group consisting of i) polyfunctional, preferably difunctional, carboxylic acids and ii) polyfunctional, preferably difunctional, hydroxy-reactive carboxylic acid derivatives e.g. Carboxylic acid chlorides, carboxylic acid alkyl esters, hydroxy-functional carboxylic acids, lactones and carboxylic acid anhydrides. In particular, the free acids or their anhydrides are used. Preference is given to compounds which are derived from an at least difunctional organic acid and are in particular selected from the group consisting of glutaric acid, succinic acid, adipic acid, terephthalic acid, phthalic acid, isophthalic acid or combinations of these, in particular glutaric acid, succinic acid, adipic acid, phthalic acid. The latter are particularly preferably combined with ethylene glycol and / or diethylene glycol.

In the subsequent second stage b), the monool is in the same way by applying an elevated temperature, for example in the range from 160 ° to 240 ° C. over a longer period of 12 to 4 hours, for example 170 ° C. and 10 hours or 180 ° C. and esterified for 6 hours or 200 ° C. and 5 hours without applying a vacuum, and thus obtain the polyester polyol PES-B with the desired functionality and hydroxyl number. Stage b) is particularly preferably carried out without solvent and / or entrainer. This second stage ensures that the monooie, which in a classical one-stage esterification due to their partly low boiling point but also due to their volatility in water vapor, possibly also due to azeotrope formation with diols during a classic esterification reaction, ie when applying Vacuum, for example 200 mbar or even 100 mbar or also 10 mbar, would be completely or partially discharged in a non-reproducible manner, can be fully implemented.

By reacting the monool with the polyester polyol PES-A in the second stage b), the polyester polyol PES-B is obtained, which has a lower number-average molecular weight and a lower functionality than the polyester polyol PES-A. It is essential that the second stage takes place without applying a vacuum, so that no starting material is carried out. The functionality of the polyester polyol PES-B can therefore be safely set using this two-stage synthesis process.

Monooies which are suitable for step b) above are therefore those whose boiling point at normal pressure is at least 125 ° C., preferably at least 140 ° C., and very particularly preferably at least 165 ° C. The monooie are preferably selected from the group consisting of 1-octanol, 2-octanol, 3-octanol, 4-octanol, 2-ethyl-1-hexanol, cis- 2-hexen-1-ol, citronellol, 1-decanol , 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol, 1-tetracosanol, preference being given to saturated alcohols with primary hydroxyl groups and less than 12 carbon atoms, and also benzyl alcohol. However, reaction products of the above-mentioned monooies, as well as of shorter-chain monooies, such as e.g. 1-hexanol, 1-butanol, 1-propanol with alkylene oxides, preferably with ethylene oxide.

The number-average functionality of the polyester polyol PES-B obtained can be calculated by calculation as follows: The molar amounts of all of the reactant molecules [n (reactant]) involved in the process, all reactive hydroxyl groups [n (OH) _reactant ] and the reactive carboxyl groups [n (carboxy ) _Educt ] of the educts used in step a) or step b) is calculated.

The molar sums of all hydroxyl end groups and separately of all carboxyl end groups of all educt molecules are calculated analogously, carboxylic anhydrides having two COOH end groups and lactones each having one hydroxyl and one carboxyl end group being included in the balance.

The difference between (excess) hydroxyl groups and (undershoot) carboxyl end groups [n (OH) _educt - n (carboxy) _educt ] gives the number of hydroxyl end groups n (OH) _pE s B- remaining in the polyester polyol _PES- B since the number of reactant molecules reduced by 1 during each esterification step (the water of reaction is discharged), the following number of polyester molecules PES-B [n (PES-B)] remains in the reaction vessel after all esterification steps, ie after complete conversion of the carboxyl groups (in the above sense): n (educts) - n (carboxy) _educt = n (PES-B)

The number-average functionality F (OH) PES B of the polyester PES-B results as follows:

F (OH) PES B = n (OH) _PES -B / n (PES-B)

This consideration does not take into account ring ester formation in the context of the present invention.

Catalysts can be used for both process steps. In principle, all catalysts known for the production of polyesters can be used as catalysts. These are, for example, tin salts, e.g. Tin dichloride, titanates, e.g. Tetrabutyl titanate or strong acids e.g. p-toluenesulfonic acid. However, the polyester polyols can also be prepared without the use of catalysts.

The hydroxyl number and thus also the number-average molar mass can be determined via the end group titration according to DIN 53240 (December 1971). The acid number can be determined according to DIN EN ISO 2114 (June 2002). The equivalent mass is determined from the experimentally determined hydroxyl number (OHZ) in mg KOH / g according to the generally known formula M _eq = 56100 / OHZ. This is a number-average equivalent mass that can be converted into the number-average molar mass (M _n ) by multiplying by the OH functionality [F (OH)], i.e. M _n = F * M _eq , or M _n = 56100 * F (OH) / OHZ.

In the context of this invention, the functionality F (OH) relates to the hydroxyl end groups. Acid end groups are not taken into account. As stated above, F (OH) is defined as the number of OH end groups divided by the number of molecules in an ensemble. F (OH) normally results from the recipe with which the polyester polyol is made, as stated above, but can in principle also alternatively be determined by Ή-NMR or other colligative methods.

Monocarboxylic acids and their derivatives can also be added to the carboxylic acid (derivative) mixture C used in stage a). There are in particular also bio-based starting materials and / or their derivatives, such as. Example, castor oil, polyhydroxy fatty acids, ricinoleic acid, hydroxyl-modified oils, grapeseed oil, black caraway oil, pumpkin seed oil, borage seed oil, soybean oil, wheat oil, rapeseed oil, sunflower seed oil, peanut oil, apricot kernel oil, pistachio oil, almond oil, olive oil, macadamia nut oil, avocado oil, sea buckthorn oil, sesame oil, hemp oil, Hazelnut oil, primrose oil, wild rose oil, safflower oil, walnut oil, fatty acids, Hydroxy-modified and epoxidized fatty acids and fatty acid esters, for example based on myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, petroselinic acid, gadoleic acid, erucic acid, nervonic acid, linoleic acid, alpha- and gamma-linolenic acid, stearidonic acid, arachidonic acid, timnodonic acid, clupanodonic acid and cervonic acid. The acid groups or carboxy functions of these monocarboxylic acids must of course be taken into account when calculating the n (OH) _{starting material} / n (carboxy) _{starting material} ratio.

The polyester polyol PES-B produced by the process according to the invention can be aliphatic or also ar-aliphatic. In this respect, according to a further preferred embodiment, the proportion of aromatic groups can be 0 to 50% by weight, in particular 0 to <50% by weight, in each case based on the starting materials, in particular mixtures of glutaric acid, succinic acid, adipic acid and / or phthalic acid as well as ethylene glycol are used. If aromatic groups are present, their proportion is> 0 to 50% by weight. The proportion of aromatics in the ester is calculated from the ester formulation by relating the amount of aromatic compound, for example phthalic anhydride or isophthalic acid, to the amount of ester obtained.

In contrast to the one-step esterification process used hitherto, the polyester polyols PES-B containing monooie can be produced reproducibly with the process according to the invention, since the full implementation of the monool is ensured due to the two-stage process. "Reproducible" in the sense of this application means that the functionalities and hydroxyl numbers can be set reproducibly in the technical sense - e.g. in a range of +/- 10%, preferably in a range of +/- 5%. The polyester polyols PES-B have e.g. Hydroxyl numbers from 150 to 300 mg KOH / g, preferably from 160 to 260, on and e.g. Number-average functionalities from <2.00, in particular 1.00 to 1.90, preferably from 1.20 to 1.80 and very particularly preferably from 1.30 to 1.79. Such polyester polyols cannot be produced in a reproducible manner using the classic one-step synthesis process.

In a preferred embodiment, the polyester polyol PES-B has 60 to 100 mol% of primary hydroxyl groups; the process is also suitable for the production of polyester polyols with less than 60 mol% primary hydroxyl groups.

In addition, the invention relates to the use of the polyester polyols PES-B according to the invention in the production of rigid polyurethane foam products, such as, for example, polyurethane insulation boards, metal composite elements, polyurethane block foam, polyurethane spray foam, polyurethane local foams or even in one - or multi-component assembly foam or as an adhesive raw material. The invention further relates to a reaction system for producing rigid PUR / PIR foams, comprising the following components:

A) an organic polyisocyanate component;

B) a polyol component,

C) if desired, auxiliaries and additives as well as blowing agents and co-blowing agents, the organic polyisocyanate component A) to components B) and optionally C) being used in such a ratio to one another that there is an index of 100 to 500, in particular 180 to 450 and the reaction system is characterized in that the polyol component B) comprises at least one polyester polyol PES-B according to the invention.

The molar ratio of all NCO groups of component A) to all NCO reactive groups in the reaction system, in the present case of components B) and C), is referred to by index or index.

The invention also relates to the use of the polyester polyols PES-B) according to the invention as or in the polyol component B) of a reaction system for the production of PUR / PIR rigid materials.

Rigid PUR / PIR foams are understood to mean those rigid polyurethane foams which contain polyisocyanurate-modified urethane structures. Such a reaction system for PUR / PIR rigid foams is preferably suitable for the production of rigid polyurethane foam products, such as, for example, polyurethane insulation boards, metal composite elements, polyurethane block foam, polyurethane spray foam, polyurethane local foams or also in one or more component assembly foam or as an adhesive raw material.

In principle, the organic polyisocyanate component is aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, such as those described by W. Siefken in Justus Liebigs Annalen der Chemie 562, pp. 75-136, e.g. those of the formula

Q (NCO) _n where n = 2-4, preferably 2-3 and Q for an aliphatic hydrocarbon radical with 2-18, preferably 6-10 carbon atoms, a cycloaliphatic hydrocarbon radical with 4-15, preferably 5-10 carbon atoms, an aromatic Hydrocarbon residue with 6-15, preferably 6-13 carbon atoms or an araliphatic hydrocarbon residue with 8-15, is preferably 8-13 carbon atoms, such as polyisocyanates, which are described in DE-OS 2.832.253, pp. 10-11, suitable.

Polyisocyanates which are technically easily accessible are normally preferred, such as 2,4- and 2,6-tolylene diisocyanate (TDI) and mixtures of these isomers. Polyphenylpolymethylene polyisocyanates such as e.g. those obtained by aniline-formaldehyde condensation and subsequent treatment with phosgene (crude MDI) and polyisocyanates containing carbodiimide, urethane, allophanate, isocyanurate, urea or biuret groups (modified polyisocyanates), especially those modified polyisocyanates derived from 2,4- and / or 2,6-tolylene diisocyanate and from 4,4'- and / or 2,4'-diphenylmethane diisocyanate.

For the production of rigid PUR / PIR foams, mixtures of isomers of diphenylmethane diisocyanate (MDI) and its oligomers are preferably used as the organic polyisocyanate component. Such mixtures are generally referred to as "polymeric MDI" (pMDI).

The polyol component contains at least one polyester polyol according to the invention and can also contain further polyol components. As such further polyol components, at least one aliphatic polyester polyol can be used which, in addition to structural units derived from adipic acid, also contains structural units which are derived from glutaric acid, succinic acid and / or phthalic acid, preferably glutaric acid and / or succinic acid.

In addition to the further aliphatic polyester polyols, the polyol component can contain further compounds with hydrogen atoms which are reactive toward isocyanate groups and which are not polyester polyols, for example polyether polyols or low-molecular chain extenders or crosslinking agents. These additives can improve the flowability of the reaction mixture and the emulsifiability of the blowing agent-containing formulation.

Flame retardants can be added to polyol component B), preferably in an amount of 5 to 50% by weight, based on the total amount of compounds having hydrogen atoms reactive toward isocyanate groups in the polyol component, in particular 7 to 35% by weight, particularly preferably 12 to 25% by weight. Such flame retardants are known in principle to the person skilled in the art and are described, for example, in “Plastics Handbook”, Volume 7 “Polyurethanes”, Chapter 6.1. This can be, for example, bromine and chlorine-containing polyols or phosphorus compounds such as the esters of orthophosphoric acid and metaphosphoric acid, which also Halogen can be included. Flame retardants which are liquid at room temperature are preferably chosen.

As much blowing agent and co-blowing agent are used as is necessary to achieve a dimensionally stable foam matrix and the desired bulk density. The proportion can be, for example, from 0 to 6.0% by weight of co-blowing agent and from 1.0 to 30.0% by weight of blowing agent, in each case based on 100% by weight of polyol component. The ratio of co-blowing agent to blowing agent can be from 20: 1 to 0: 100 as required.

Hydrocarbons, e.g. the isomers of pentane, or hydrofluorocarbons, e.g. HFC 245fa (1,1,1,3,3-pentafluoropropane), HFC 365mfc (1,1,1,3,3-pentafluorobutane) or mixtures thereof with HFC 227ea (heptafluoropropane). Different classes of blowing agents can also be combined. For example, with mixtures of n- or c-pentane with HFC 245fa in the ratio 75:25 (n- / c-pentane: HFC 245fa) achieve thermal conductivities, measured at 10 ° C, of less than 20 mW / mK.

Water and / or formic acid can also be used as co-blowing agent, preferably in an amount of up to 6% by weight, preferably 0.5 to 4% by weight, based on the total amount of compounds with water atoms which are reactive toward isocyanate groups the polyol component. However, water cannot be used.

Catalysts customary in polyurethane chemistry are advantageously added to the polyol component. The amine catalysts required for the production of a rigid PUR / PIR foam and the salts used as trimerization catalysts are used in such an amount that e.g. On continuously producing systems, elements with flexible cover layers can be produced at speeds of up to 60 m / min depending on the element thickness, as well as for insulation on pipes, walls, roofs and tanks and in refrigerators using the spray foam process with sufficient curing time. Batch production is also possible.

Examples of such catalysts are: triethylenediamine, N, N-dimethylcyclohexylamine, tetra methylenediamine, l-methyl-4-dimethylaminoethylpiperazine, triethylamine, tributylamine, dimethylbenzylamine, N, N ', N "-Tris- (dimcthylaminopropyl) hxxahydrotriazine, dimethylaminopropyl amide, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N'-tetramethylbutanediamine, tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, dimethylpiperazine, 1, 2-dimethylimidazole, 1-azabicyclo [3.3] , Bis (dimethylaminopropyl) urea, N-methylmorpholine, N-ethylmorpholine, N-cyclohexylmorpholine, 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, triethanolamine, diethanolamine, triisopropanolamine, N-methyldiethanolamine , N- Ethyldiethanolamine, dimethylethanolamine, tin (II) acetate, tin (II) octoate, tin (II) ethylhexoate, tin (II) laurate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, dioctyltin (diacetate), tri -dimethylaminopropyl) -s-hexahydrotriazine, tetramethylammonium hydroxide, sodium acetate, sodium octoate, potassium acetate, potassium octoate, sodium hydroxide or mixtures of these catalysts.

Foam stabilizers can also be added to the polyol component, for which purpose polyether siloxanes are particularly suitable. These compounds are generally constructed in such a way that a copolymer of ethylene oxide and propylene oxide is linked to a polydimethylsiloxane radical. Such substances are available on the market, for example, under the name Struksilon 8031 from Schill and Seilacher or TEGOSTAB® B 8443 from Evonik. Silicone-free stabilizers, such as the product LK 443 from Air Products, can also be used.

In a preferred embodiment of the reaction system according to the invention, the weight ratio of components A) and B) to one another is from 100: 150 to 100: 300, in particular from 100: 180 to 100: 250.

The polyester polyols PES-B produced by the process according to the invention are particularly well suited for use in PUR-PIR rigid foam formulations. The PUR / PIR rigid foams produced with the polyester polyols have a combination of good fire protection properties and mechanical properties.

Another object of the invention is a process for the production of rigid PUR / PIR foams, in which components A) and B) and optionally C) of a reaction system according to the invention are mixed with one another and allowed to react.

The PUR / PIR rigid foams according to the invention are typically produced by the one-step process known to the person skilled in the art, in which the reaction components are reacted with one another continuously or discontinuously and then either manually or with the aid of mechanical equipment in a high-pressure or low-pressure process after discharge Conveyor belt or be brought into suitable forms for curing. Examples are in US-A 2,764,565, in G. Oertel (ed.) "Kunststoff-Handbuch", Volume VII, Carl Hanser Verlag, 3rd edition, Munich 1993, p. 267 ff., And in K. Uhlig ( Ed.) "Polyurethane Taschenbuch", Carl Hanser Verlag, 2nd edition, Vienna 2001, pp. 83-102.

The invention also relates to a rigid foam which can be obtained by mixing and reacting components A) and B) and, if appropriate, C) of a reaction system according to the invention. Such a rigid foam can be used in various fields of application, especially as an insulating material. Examples from the construction industry are wall insulation, pipe shells or pipe half-shells, roof insulation, wall elements and floor panels. In particular, the rigid foam can be in the form of an insulation board or as a composite element with flexible or non-flexible cover layers and have a density of 25 to 65 kg / m ³ , in particular 30 to 45 kg / m ³ . In another embodiment, the rigid foam can be in the form of block foam and have a density of 25 to 300 kg / m ³ , in particular 30 to 80 kg / m ³ .

The invention also relates to the PUR / PIR rigid foams containing laminates according to the invention. These have a core of rigid PUR / PIR foam according to the invention and cover layers firmly connected to it. The cover layers can be flexible or rigid. Examples are paper cover layers, fleece cover layers, metal cover layers (e.g. steel, aluminum) and composite cover layers. The cover layers are decoiled from a roll and if necessary profiled, if necessary heated and if necessary corona treated in order to improve the foamability of the cover layers. A primer can also be applied to the lower top layer before applying the rigid polyisocyanurate foam system.

The production of such laminates is known in principle to the person skilled in the art and is described, for example, in G. Oertel (ed.) “Kunststoff-Handbuch”, Volume VII, Carl Hanser Verlag, 3rd edition, Munich 1993, pp. 272-277. It is preferably carried out by the double conveyor belt process, the laminates according to the invention being able to be produced without problems at belt speeds of up to 60 m / min. The laminates made from the PUR / PIR foams according to the invention show particularly good adhesion, particularly in long-term tests.

Examples

The experiments marked with a * are comparative examples.

Raw materials and methods used:

TCPP trischloroisopropyl phosphate (Levagard ^® PP, Lanxess AG),

Flame retardant

TEP Levagard ^® TEP, Lanxess AG, flame retardant, triethyl phosphate

Kat-1 Desmorapid® DB, Covestro Deutschland AG, is an activator for the

Production of rigid polyurethane (PUR) foams based on a tert. Amine.

B 8443 TEGOSTAB® B 8443 from Evonik is a non-hydrolyzable

Polyether polydimethylsiloxane copolymer

Cat-2 Desmorapid.RTM ^® 1792 Covestro Germany AG.

Preparation containing diethylene glycol and potassium acetate. Trimersization catalyst.

B-l polyether polyol based on ortho-toluenediamine, ethylene oxide and

Propylene oxide with an OH number of 415 mg KOH / g from Covestro Deutschland AG, viscosity measured at 25 ° C. approx. 8000 mPas.

B-2 polyester polyol from phthalic anhydride and diethylene glycol, OH number

795 mg KOH / g from Covestro Deutschland AG, viscosity 160 mPas at 25 ° C, acidity 97 mg KOH / g.

PES-Bl * Bifunctional polyester polyol made from technical glutaric acid and

Ethylene glycol from Covestro Deutschland AG for the production of PUR PIR rigid foams with a hydroxyl number of approx. 240 mg KOH / g, an acid number of approx. 1.75 mg KOH / g and a viscosity of approx 15590 mPas.

Al Desmodur ^® 44V70L, polymeric MDI from Covestro Deutschland AG with an NCO content of 30.5 to 32% by weight

Glutaric acid, technical Lanxess AG

Benzoic Acros

1-Decanol but GmbH

Ethylene glycol INEOS AG

n-Pentan Kraemer & Martin GmbH The analyzes were carried out as follows:

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

Hydroxyl number: based on the standard DIN 53240 (December 1971)

Acid number: based on the standard DIN EN ISO 2114 (June 2002)

The mechanical properties were determined by means of a tensile test according to EN 1607 (DIN EN 14509) in the version from May 2013, whereby the force was applied perpendicular to the top layer, i.e. in the direction of foaming. This measurement results in the measurement parameters E-module (also called Young’s module).

In addition, a pressure test was carried out in the direction of foaming in accordance with DIN EN 826 (version of 05/2013), whereby the measurement parameters E-module (also called Young’s module) were also used.

Furthermore, a pressure test perpendicular to the foaming direction according to DIN EN 826 (version of 05/2013), whereby the measured values E-module (also called Young’s module).

The fire properties were determined in accordance with DIN 4102-1 (May 1998 version), whereby the largest flame height and the destroyed sample length are given as measurement parameters for five individual samples.

Bulk density: was determined according to DIN EN ISO 845 (version from October 2009)

Open cell according to DIN EN ISO 4590 (version from June 2014)

Start time: The time that elapses from the start of mixing the main components to the visible start of foaming of the mixture.

Setting time: The setting time ("gel point tc") is determined by dipping a wooden stick into the reacting mixture and taking it out again. It characterizes the point in time from which the mixture hardens. The tc is the time at which threads can first be drawn between the wooden stick and the reacting mixture. The time measurement starts with the mixing of the foam components. Tack free time: Shortly after setting time is reached with a wooden stick in short

The foam surface is scanned at intervals. Starting from the start of the mixing, the adhesive free time is reached when the wooden stick detaches from the foam surface effortlessly, without adhering product.

The functionality is calculated based on the functionality of the starting materials used.

1. Preparation of the polyester polyols

Polyester polyol PES-B2 *:

In a 4 liter four-necked flask equipped with a mechanical stirrer, 50 cm packed column, thermometer, nitrogen inlet, and column top, distillation bridge and vacuum membrane pump, 1797 g (13.41 mol, 56.15% by weight) of technical glutaric acid were 188 g (1.54 mol, 5.88% by weight) of benzoic acid and 1215 g (19.57 mol, 37.97% by weight) of ethylene glycol were initially charged and covered with nitrogen over a period of 60 minutes. heated to 200 ° C, water of reaction distilled off; this distillate was single phase and had a pH of 7. After 5 hours the pressure was slowly reduced to 200 mbar in the course of 3 hours. The reaction was allowed to take 40 hours under these conditions, the OHZ determined to be 176 mg KOH / g and the acid number 1.1 mg KOH / g. Discharged ethylene glycol (57.6 g) was added and stirred in for a further 6 hours at 160 ° C. under normal pressure.

Analysis of the polyester PES-B2 *:

Hydroxyl number: 209.8 mg KOH / g

Acid number: 0.9 mg KOH / g

Viscosity: 1000 mPas (25 ° C)

Functionality: 1.75

Polyester polyol PES-B3 *: a) 1661 g (12.40 mol, 51.91.) Were in a 4-liter four-necked flask equipped with mechanical stirrer, 50 cm packed column, thermometer, nitrogen inlet, as well as column head, distillation bridge and vacuum membrane pump % By weight) of technical glutaric acid, 381 g (3.13 mol, 11.93% by weight) of benzoic acid and 1157 g (18.65 mol, 36.20% by weight) of ethylene glycol and with nitrogen blanketing in the course of 60 min. heated to 200 ° C, water of reaction distilled off. After 5 For hours, the pressure was slowly reduced to 200 mbar in the course of 3 hours. The reaction was allowed to react for 40 hours under these conditions; the distillates were single phase and had a pH of 7. The OHZ was determined to be 154.4 mg KOH / g and the acid number was 1.4 mg KOH / g. Discharged ethylene glycol (42.4 g, 0.68 mol) was added and stirred in for a further 6 hours at 200 ° C. under normal pressure.

Analysis of polyester B-3 *:

Hydroxyl number: 179.2 mg KOH / g

Acid number: 1.23 mg KOH / g

Viscosity: 1010 mPas (25 ° C)

Functionality: 1.50

Polyester polyol PES-B4: a) In a 4-liter four-necked flask equipped with mechanical stirrer, 50 cm packed column, thermometer, nitrogen inlet, as well as column head, distillation bridge and vacuum membrane pump, 1680 g (12.54 mol) technical glutaric acid and 1045 g (16.83 mol) of ethylene glycol and with nitrogen blanketing in the course of 60 min. heated to 200 ° C, water of reaction distilled off. After 3 hours the pressure was slowly reduced to 30 mbar in the course of 3 hours. The reaction was allowed to continue for 24 hours under these conditions. The OHZ was determined to be 159.8 mg KOH / g and the acid number was 0.5 mg KOH / g. Discharged ethylene glycol (74 g, 1.19 mol) was added and stirred in for a further 6 hours at 200 ° C. under normal pressure. The OHZ was determined to be 210.2 mg KOH / g and the acid number to 0.47 mg KOH / g. b) 227 g (1.43 mol) of 1-decanol were then added and the mixture was stirred at 200 ° C. for 6 hours under normal pressure.

Analysis of the polyester PES-B4:

Hydroxyl number: 219.9 mg KOH / g

Acid number: 0.5 mg KOH / g

Viscosity: 580 mPas (25 ° C)

Functionality: 1.75 Polyester polyol PES-B5 *, comparative example:

1367 g (10.21 mol) of technical glutaric acid, 826 g (13.30 mol) were placed in a 4-liter four-necked flask equipped with a mechanical stirrer, 50 cm packed column, thermometer, nitrogen inlet, and column head, distillation bridge and vacuum membrane pump. Ethylene glycol and 490 g (3.1 mol) of 1-decanol submitted and with nitrogen blanketing in the course of 60 min. heated to 200 ° C, water of reaction, which was cloudy and separated into two phases, distilled off. After 3 hours the pressure was slowly reduced to 250 mbar in the course of 2 hours. The reaction was allowed to take place for 15 hours under these conditions, with further water, which formed two phases, being separated. The OHZ was determined to be 145.9 mg KOH / g and the acid number was 1.3 mg KOH / g.

It must be concluded from the two-phase nature of the water of reaction that it contains 1-decanol; from Examples A-4, PES-B3 and PES-B2 it is known that ethylene glycol is also discharged under these conditions. 1-decanol is known to dissolve only slightly in water (approx. 40 mg / 1). However, since the water phase also contains ethylene glycol, certain parts of 1-decanol in the water phase containing ethylene glycol presumably dissolve as well as certain parts of ethylene glycol in the 1-decanol phase. Since precise knowledge of the amounts distilled off and the amounts of ethylene glycol and 1-decanol to be replenished are essential to adjust the functionality of the polyester polyol, but these can only be determined experimentally with great effort, the approach had to be rejected. A monool together with diol cannot be reproducibly implemented in this way in a one-step esterification.

Polyester polyol PES-B6 *, comparative example:

In a 4-liter four-necked flask equipped with a mechanical stirrer, 50 cm packed column, thermometer, nitrogen inlet, and column top, distillation bridge and vacuum membrane pump, 1124.5 g (8.39 mol) technical glutaric acid, 279.8 g (0 , 99 mol) of oleic acid and 1445.2 g (13.6 mol) of diethylene glycol and with nitrogen blanketing in the course of 60 min. heated to 200 ° C, water of reaction distilled off. After 4 hours the pressure was slowly reduced to 100 mbar in the course of 3 hours. The reaction was allowed to continue for 24 hours under these conditions. The OHZ was determined to be 180 mg KOH / g and the acid number was 0.7 mg KOH / g. Discharged diethylene glycol (58 g, 0.55 mol) was added and stirred in for a further 5 hours at 200 ° C. under normal pressure.

Analysis of the polyester PES-B6 *:

Hydroxyl number: 199.4 mg KOH / g

Acid number: 0.9 mg KOH / g

Viscosity: 540 mPas (25 ° C)

Table 1: Recipes and properties of polyester polyols PES-B according to the invention and not according to the invention

2. Production of the PUR / PIR rigid foams:

Rigid PUR / PIR foams were produced on the basis of the aforementioned polyester polyols PES-B. For this purpose, the respective polyester polyol PES-B according to Table 2 was presented with the other polyols B1 and B-2, and mixed with the flame retardant, a foam stabilizer based on polyether siloxane, catalysts and n-pentane as blowing agent, the mixture thus obtained with polyisocyanate Al mixed and the mixture poured into a wooden box mold open to the top (30x30x10 cm ³ ) and reacted therein. The formulations and results of the physical measurements on the samples obtained are shown in Table 2.

Table 2: Production and properties of (comparison, *) PUR-PIR rigid foams according to the invention and not according to the invention

Table 2 shows that PUR-PIR rigid foams based on the polyols PES-B4 according to the invention are significantly superior to the PUR-PIR rigid foam based on the non-inventive polyol PES-B 1 in terms of fire properties and are equivalent to the polyols PES-B2 and PES -B3 are. The essential difference between the polyol PES-B4 according to the invention and the polyol PES-B 1 not according to the invention consists only in the functionality of the polyester polyol used. All other recipe components are except for the amount of isocyanate identical in their amounts used, although different amounts of isocyanate were required in order to keep the key figures of all formulations at 300 also the same. The bulk densities of all foams are also in a very narrow window. There are no major differences in the processing behavior as there are in the mechanical properties. In all cases, closed-cell, fine-line, dimensionally stable, foams were obtained. PES-B4 is a good alternative to the well-known polyester polyols PES-B2 and PES-B3. The method according to the invention enables the reproducible production of the polyester polyol PES-B4 and enables the use of monoesters for the production of polyester polyols.

Claims

1. Multi-stage process for the preparation of a polyester polyol PES-B comprising the steps a) complete conversion of at least one carboxyl compound selected from the group consisting of i) polyfunctional, preferably difunctional, carboxylic acids and ii) polyfunctional, preferably difunctional, hydroxy-reactive carboxylic acid derivatives selected from the group consisting of carboxylic acid chlorides, carboxylic acid alkyl esters, hydroxy-functional carboxylic acids, lactones and carboxylic acid anhydrides with at least one polyol containing 2-8 hydroxyl groups to form a polyester polyol PES-A, in which step a) the ratio of the molar amount of hydroxyl groups used [n (OH) _a ] to molar amount of carboxyl equivalent groups [n (carboxy) _a ]: n (OH) _a / n (carboxy) a>1; b) subsequent reaction of the polyester polyol PES-A obtained in step a) with a monofunctional alcohol (monool) to give the PES-B, the ratio of the molar sum of the hydroxyl groups n (OH) _{starting material used} in steps a) and b) Educt molecules to the molar sum of the carboxyl-equivalent groups n (carboxy) _{educt used} : n (OH) _educt / n (carboxy) _educt > 1.

2. The method according to claim 1, wherein the polyester polyols PES-B have a number-average OH functionality of> 1.00 to <2.00.

3. The method according to any one of the preceding claims, wherein the carboxyl compound in step a) is selected from the group consisting of glutaric acid, succinic acid, Adipic acid, terephthalic acid, phthalic acid, isophthalic acid and their derivatives, or combinations of these, in particular combinations of glutaric acid, succinic acid, adipic acid and / or phthalic acid.

4. The method according to any one of the preceding claims, wherein the at least one polyol in step a) is selected from the group consisting of polyols containing 2-3 hydroxyl groups, in particular 2- 2.5 hydroxyl groups.

5. The method according to claim 4, wherein the at least one polyol in stage a) is selected from the group consisting of polyols containing 2 hydroxyl groups, in particular ethylene glycol and / or diethylene glycol.

6. The method according to any one of the preceding claims, wherein the monool is selected from at least one compound from the group consisting of 1-octanol, 2-octanol, 3-octanol, 4-octanol, 2-ethyl-1-hexanol, cis- 2-hexen-l-ol, citronellol, 1-decanol, 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol, 1-tetracosanol and benzyl alcohol.

7. The method according to any one of the preceding claims, wherein the monool is selected from at least one compound from the group consisting of reaction products of monooien with alkylene oxides, preferably with ethylene oxide, in particular 1-hexanol, 1-butanol, 1-propanol, 1-octanol , 2-octanol, 3-octanol, 4-octanol, 2-ethyl-l-hexanol, cis-2-hexen-l-ol, citronellol, 1-decanol, 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1 -Octadecanol, 1-tetracosanol and benzyl alcohol.

8. polyester polyol obtainable by a process according to any one of claims 1-7.

9. polyester polyol according to claim 8 with a hydroxyl number of 150 to 300 mg KOH / g, preferably from 160 to 260, and a number-average functionalities of 1.00 to <2.00.

10. PUR / PIR - rigid foam containing a polyester polyol according to claim 8 or 9.

11. Reaction system for the production of PUR and PIR rigid foams, comprising the following components:

A) an organic polyisocyanate component;

B) a polyol component

C) optionally auxiliaries and additives as well as blowing agents and co-blowing agents, the organic polyisocyanate component A) to components B) and optionally C) being used in such a ratio to one another that there is an index of 100 to 500, in particular 180 to 450 and the reaction system is characterized in that the polyol component B) comprises at least one polyester polyol according to one of claims 9 to 10.

12. A process for the production of rigid PUR and PIR foams, in which components A) and B) and, if desired, C) of a reaction system according to claim 11 are mixed together and allowed to react.

13. PUR / PIR rigid foam, obtainable by mixing and reacting components A) and B) and, if desired, C) a reaction system according to claim 11 or 12.

14. rigid foam according to claim 13, characterized in that the rigid foam is in the form of an insulation board or as a composite element with flexible or non-flexible cover layers and has a density of 25 to 65 kg / m ³ , in particular 30 to 45 kg / m3 or that the rigid foam is in the form of block foam and has a density of 25 to 300 kg / m ³ , in particular 30 to 80 kg / m3.