EP2542607A1

EP2542607A1 - Method for producing polyurethane hard foam materials

Info

Publication number: EP2542607A1
Application number: EP11704463A
Authority: EP
Inventors: Berend Eling; Markus SCHÜTTE; Sirus Zarbakhsh; Holger Seifert; Gunnar Kampf
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2010-03-02
Filing date: 2011-02-22
Publication date: 2013-01-09
Also published as: MX2012009972A; CN102781996A; WO2011107374A1; SG183358A1; BR112012021916A2; RU2012141625A; JP2013521356A; KR20130045853A

Abstract

The invention relates to a method for producing polyurethane hard foam materials by reacting a) polyisocyanates with b) compounds having at least two hydrogen atoms reactive with two isocyanate groups in the presence of c) foaming agents, characterized in that the compounds having at least two hydrogen atoms reactive with two isocyanate groups comprise at least one polyether alcohol b1) having a functionality of 2-8 and a hydroxyl number of 200-800 mg KOH/g, said alcohol having been produced by building up alkylene oxides b1b) on compounds having at least two hydrogen atoms reactive with alkylene oxides b1a), referred to below as starting substances, using an amine b1c) as a catalyst.

Description

Process for the production of rigid polyurethane foams. The invention relates to a process for the production of rigid polyurethane foams by reacting polyisocyanates with compounds having at least two isocyanate-reactive hydrogen atoms in the presence of blowing agents. Polyurethane rigid foams have long been known and are mainly used for thermal and cold insulation, z. B. in refrigerators, in hot water tanks, in district heating pipes or in construction, for example in sandwich panels used. A summary of the production and application of rigid polyurethane foams can be found, for example, in the Kunststoff-Handbuch, Volume 7, Polyurethane 1st Edition 1966, edited by Dr. med. R. Vieweg and dr. A. Höchtlen, and 2nd edition, 1983, edited by dr. Günter Oertel, and 3rd edition 1993, edited by Dr. med. Günter Oertel, Carl Hanser Verlag, Munich, Vienna.

Fluorochloroalkanes (CFCs), preferably trichlorofluoromethane, have mostly been used in the past as blowing agents for the production of rigid polyurethane foams. However, a disadvantage of these propellants is the pollution of the environment.

In the meantime, hydrocarbons, preferably pentanes, are mostly used as successors to CFCs. Thus, EP-A-421 269 describes the use of cyclopentane and / or cyclohexane, optionally mixed with other hydrocarbons, as blowing agent.

However, these propellants differ in various respects from the halogenated propellants. So they are less compatible with the other components of the polyurethane systems. This leads to a rapid separation of the components containing blowing agent.

Furthermore, less blowing agent can be incorporated into the components. Therefore, the alkane-driven foams tend to have a higher density than those driven by CFCs.

Therefore, there is a demand to reduce the density of the foams in order to save material without, however, causing a deterioration of the thermal conductivity or the mechanical properties of the polyurethanes. It should be carried out in the foaming of cavities, such as housings of refrigeration furniture, a uniform filling of the cavity, that is, the liquid components must flow into all parts of the cavity. If the flow rate is too low Like the foams, it is necessary in cavities with large volume and / or complicated geometry, to overfill the cavity with foam, wherein the resulting pressure ensures a uniform distribution of the foam. The better the liquid build-up components fill the cavities, the less rigid polyurethane foam is needed to completely foam the cavity. Thus, the polyurethane rigid foam located in the cavity has a lower density, which in addition to the saving of material also leads to a reduction in the weight of the end products, such as refrigerated cabinets. Flowability of the foam is understood to mean the flow behavior of the reacting mixture of polyisocyanate and the compound having at least two hydrogen atoms reactive with isocyanate groups. Flowability is usually determined by determining the path length that the reacting mixture travels. This can be done by the reaction mixture in a flexible hose made of plastic film, hereinafter referred to as a hose test, or in a normalized elongated shape, for example, a so-called Boschlanze introduced, and the length of the resulting shaped body is determined.

The flowability of the reaction mixtures is usually determined by determining the flow factor. The flow factor represents the ratio of minimum filling density to free-foamed density and is determined with the help of the Boschlanze. The minimum filling density is obtained by varying the shot weight and corresponds to the minimum necessary density, which is required to fill a Boschlanze completely for a given free density.

It was the object of the present invention to provide a process for the production of rigid polyurethane foams in which the polyol components have a better solubility for the hydrocarbons used as propellant. Furthermore, improved processing properties should be achieved, in particular better flowability. In addition, foams with good mechanical properties and low thermal conductivities should be obtained.

The object could surprisingly be achieved by the use of polyols, which were prepared by addition of alkylene oxides to compounds having at least two active hydrogen atoms in the presence of at least one compound having at least one amino group as catalyst.

Compounds which have been prepared by addition of alkylene oxides onto compounds having at least two active hydrogen atoms in the presence of at least one compound having at least one amino group as catalyst are known. In US 20070203319 and US 20070199976 polyether alcohols are described which are prepared by addition of alkylene oxides by means of dimethylethanolamine to starter substances which contain solid compounds at room temperature. However, no polyurethanes prepared using these polyols are described. Nor is there any reference in this document to the properties of the described polyols in the production of the foams and their effects on the properties of the foams.

The invention relates to a process for the preparation of rigid polyurethane foams by reacting a) polyisocyanates with b) compounds having at least two isocyanate-reactive hydrogen atoms in the presence of c) blowing agents, characterized in that the compounds have at least two isocyanates. natgruppen reactive hydrogen atoms b) at least one polyether alcohol b1) having a functionality of 2-8 and a hydroxyl number of 200-800 mgKOH / g, by addition of alkylene oxides b1 b) to compounds having at least two reactive with alkylene oxides hydrogen atoms b1 a), hereinafter also referred to as starter substances, using an amine b1 c) was prepared as a catalyst.

The polyether alcohol b1) can be used as the only compound of component b). The polyether alcohol b1) is preferably used in an amount of 10-90% by weight, based on the weight of component b).

For the preparation of the polyether alcohol b1), it is preferred to use mixtures containing at least two hydrogen atoms reactive with alkylene oxides which contain at least one compound bl ai) which is solid at room temperature. The compound bl ai) preferably has a functionality of at least 3, particularly preferably of at least 4, in particular of 3-8 and particularly preferably of 4-8.

Such compounds bl ai) are known and are frequently used for the preparation of polyether alcohols, in particular those for use in rigid polyurethane foams. Preferably, the compounds bl ai) are selected from the group comprising trimethylolpropane, pentaerythritol, glucose, sorbitol, mannitol and Sucrose, polyhydric phenols, resoles, such as oligomeric condensation products of phenol and formaldehyde, oligomeric condensation products of aniline and formaldehyde (MDA), toluenediamine (TDA) and Mannich condensates of phenols, formaldehyde and dialkanolamines and melamine and mixtures of at least two of the listed alcohols ,

In a preferred embodiment of the invention, the compound bl ai) is selected from the group comprising sucrose, sorbitol and pentaerythritol, more preferably sucrose or sorbitol. In a particularly preferred embodiment of the invention, b1 is a) sucrose.

The aromatic amines used as compounds bl ai) are in particular selected from the group comprising toluenediamine (TDA) or diphenylmethanediamine (MDA) or polymeric MDA (p-MDA). In particular, the 2,3- and 3,4-isomers, also referred to as vicinal TDA, are used in TDA.

As a starting substance, it is also possible to use compounds having at least two hydrogen atoms b1a) which are reactive with alkylene oxides and contain at least one compound a) which is liquid at room temperature.

In a preferred embodiment of the invention, the starter substance of component b1) contains, in addition to the compound bl ai), a compound bl aii) which is liquid at room temperature and contains hydrogen atoms reactive with alkylene oxides. The compound bl aii) may be alcohols or amines. These have, in particular, 1 to 4, preferably 2 to 4, hydrogen atoms reactive with alkylene oxides. The component bl aii) is in particular selected from the group comprising glycerol, monofunctional alcohols having 1-20 carbon atoms, ethylene glycol and its higher homologues and propylene glycol and its higher homologs, hydroxyalkylamines, such as monoethanolamine, diethanolamine, triethanolamine, and their reaction products with propylene oxide. In particular, glycerol is used.

The liquid at room temperature (bl aii) may, as I said, also be compounds having a reactive with alkylene oxides hydrogen atom and 1-20 carbon atoms. Preference is given here to monofunctional alcohols, such as methanol, ethanol, propanol, octanol, dodecanol.

In a further embodiment of the invention, the starting substance of component b1) comprises a mixture of at least one amine blAi) which is solid at room temperature and an alcohol which is liquid at room temperature.

The amines bl ai) which are solid at room temperature may, as stated above, preferably be MDA and polymeric MDA. At the room temperature liquid alcohols bl aii) are then preferably ethylene glycol and its higher homologues and propylene glycol and its higher homologues. The concentrations of the amine homologs in p-MDA are dependent on the process operations. In general, the distribution (in weight percent) is as follows:

Binuclear MDA: 50-80% by weight

Trinuclear MDA: 10-25% by weight

Four-core MDA: 5-12% by weight

Five- and higher-nucleated MDA: 5-12% by weight

A preferred p-MDA mixture has the composition:

Dual Core MDA: 50% by weight

Trinuclear MDA: 25% by weight

Four-core MDA: 12% by weight

Five- and higher-nucleated MDA: 13% by weight

Another preferred p-MDA mixture has the composition: binuclear MDA: 80% by weight

Trinuclear MDA: 10% by weight

Four-core MDA: 5% by weight

Five- and higher-nuclear MDA: 5% by weight In a further preferred embodiment of the invention, the starting substance of component b1) contains a mixture of at least one (bl ai)) which is solid at room temperature and an alcohol which is liquid at room temperature (bl aii)). The alcohols (bl ai) which are solid at room temperature are preferably the sugar alcohols glucose, sorbitol, mannitol and sucrose, in particular sucrose, characterized in detail above. The liquid at room temperature alcohols (bl aii) are preferably monofunctional alcohols having 1-20 carbon atoms, ethylene glycol and its higher homologues, propylene glycol and its higher homologs, hydroxyalkylamines, such as monoethanolamine, diethanolamine, triethanolamine, as well as their propylene oxide based analogues and glycerin, especially glycerin. The starting substance of component b1) may also contain water. If water is also used, the amount is in particular at most 25 wt .-%, based on the weight of the starting substance of component b1).

The alkylene oxide b1 b) used is preferably propylene oxide, ethylene oxide, butylene oxide, isobutylene oxide, styrene oxide or mixtures of at least two of the abovementioned alkylene oxides. Preferably, as alkylene oxide b1 b) propylene oxide, ethylene oxide or mixtures of propylene oxide and ethylene oxide used. Particular preference is given to using alkylene oxide b1b) as propylene oxide.

As described above, catalyst b1 c) is one of the components used as component (a)). These may be primary, secondary or tertiary amines and also aliphatic or aromatic, in particular tertiary amines. In another embodiment, it may be aromatic heterocyclic compounds having at least one, preferably a nitrogen atom in the ring. The amines b1 c) are preferably selected from the group comprising trialkylamines, in particular trimethylamine, triethylamine, tripropylamine, tributylamine, dimethylalkylamines, in particular dimethylethanolamine; Dimethylethoxyethanolamine, dimethylcyclohexylamine, dimethylethylamine, dimethylbutylamine, aromatic amines, in particular dimethylaniline, dimethylaminopyridine, dimethylbenzylamine, pyridine, imidazoles, in particular imidazole, N-methylimidazole, 2-methylimidazole, 4-methylimidazole, 5-methylimidazole, 2-ethyl-4-methylimidazole 2,4-dimethylimidazole, 1-hydroxypropylimidazole, 2,4,5-trimethylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, N-phenylimidazole, 2-phenylimidazole, 4-phenylimidazole, guanidine, alkylated guanidines, especially 1, 1, 3,3-tetramethylguanidine, 7-methyl-1, 5,7-triazabicyclo [4.4.0] dec-5-ene, amidines, in particular 1, 5-diazobicylco [4.3.0] -non- 5-ene, 1, 5-diazabicyclo [5.4.0] undec-7-ene.

It is also possible to use as catalysts mixtures of at least two of said amines.

In a preferred embodiment of the invention, the catalyst b1 c) is dimethylethanolamine.

In a preferred embodiment of the invention, the catalyst b1 c) is an imidazole.

The amine b1 c) is preferably present in an amount of 0.01-5.0 wt .-%, preferably 0.05-3.0 wt .-% and particularly preferably 0.1 -1, 0 wt .-% based on the overall approach, used. Under Gesamtansatz the amount of all starting materials used for the preparation of the polyether alcohol b1) is understood.

To prepare the polyether alcohols b1), the constituents of the starting substance mixture b1 a) and b1c) are usually added to the reactor and mixed. There is initially an inerting of the mixture. Thereafter, the alkylene oxide is metered.

The addition of the alkylene oxides is preferably carried out at a temperature between 90 and 150 ° C and a pressure between 0.1 to 8 bar. To the dosage of Alkylene oxides usually include a post-reaction phase for complete conversion of the alkylene oxides.

After completion of the metering of the alkylene oxides usually followed by a post-reaction phase, in which the alkylene oxide reacts. Thereafter, if necessary, a post-reaction phase can follow. It usually follows a distillation for the separation of volatile components, preferably under vacuum.

The amine catalysts b1 c) can remain in the polyether alcohol. This simplifies their preparation, since the removal of the catalysts necessary when using oxides and hydroxides of alkali metals is no longer necessary. This leads to an improvement in the space-time yield. The salt removal by filtration forms a filter cake. The polyol loss in the filter cake is usually a few percent. The improved space-time yield and avoidance of filter loss lead to a reduction in manufacturing costs.

It is also possible to use a combination of alkali metal hydroxide and amine catalysts. This is particularly suitable for producing polyols with a low hydroxyl number. The products obtained can be worked up analogously to the alkali metal hydroxide-catalyzed polyols. Alternatively, only the neutralization step with acid can be carried out for workup. In this case, it is preferred to use carboxylic acids, e.g. Michsäure, acetic acid or 2-ethylhexanoic acid used. The amine catalysts b1 c) can themselves be alkoxylated in the course of the reaction. The alkoxylated amines therefore have a higher molecular weight and a lower volatility in the later product. Due to the remaining self-reactivity of the alkoxylated amine catalysts, incorporation into the polymer backbone occurs during later reaction with isocyanates. The intrinsic reactivity of the tertiary amines formed gives the polyols an intrinsic reactivity that can be used to advantage in certain applications.

Without wishing to be bound by theory, it is believed that the polyether alcohols prepared using amines as catalysts have a structure different from the construction of such polyether alcohols made using other catalysts. This different molecular structure has advantages in the production of polyurethanes.

Thus, the polyols of the invention have distinct advantages in polyurethane applications, especially in the production process of polyurethane foams. As described, the polyether alcohols b1) are used for the preparation of polyurethanes.

The following can be said in detail about the starting materials used for this purpose:

Suitable organic polyisocyanates are preferably aromatic polyfunctional isocyanates.

Specific examples include: 2,4- and 2,6-toluene diisocyanate (TDI) and the corresponding isomer mixtures, 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate (MDI ) and the corresponding mixtures of isomers, mixtures of 4,4'- and 2,4'-diphenylmethane diisocyanates and in the production of rigid polyurethane foams in particular mixtures of 4,4'-, 2,4'- and 2,2'- Diphenylmethane diisocyanates and polyphenyl polymethylene polyisocyanates (crude MDI).

The polyether alcohols b1) according to the invention are usually used in admixture with other compounds having at least two isocyanate-reactive hydrogen atoms. Suitable compounds having at least two isocyanate-reactive hydrogen atoms which can be used together with the polyether alcohols b1) are, in particular, polyether alcohols and / or polyester alcohols having OH numbers in the range from 100 to 1200 mgKOH / g. The polyester alcohols used together with the polyether alcohols b1) are usually obtained by condensation of polyfunctional alcohols, preferably diols, having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, with polyfunctional carboxylic acids having 2 to 12 carbon atoms, for example succinic acid, glutaric acid, adipic acid, Nuclear acid, azelaic acid, sebacic acid, decane dicarboxylic acid, maleic acid, fumaric acid and preferably phthalic acid, isophthalic acid, terephthalic acid and the isomeric naphthalenedicarboxylic acids.

The polyether alcohols used together with the polyether alcohols b1) usually have a functionality between 2 and 8, in particular 3 to 8.

In particular, polyether alcohols which are prepared by known processes, for example by anionic polymerization of alkylene oxides in the presence of catalysts, preferably alkali metal hydroxides, are used. As alkylene oxides are usually ethylene oxide and / or propylene oxide, preferably pure 1, 2-propylene oxide used. In particular, compounds having at least 3, preferably 4 to 8 hydroxyl groups or having at least two primary amino groups in the molecule are used as starting molecules. As starting molecules having at least 3, preferably 4 to 8 hydroxyl groups in the molecule are preferably trimethylopropane, glycerol, pentaerythritol, sugar compounds such as glucose, sorbitol, mannitol and sucrose, polyhydric phenols, resoles, such as oligomeric condensation products of phenol and formaldehyde, condensation products of aniline and Formaldehyde, toluene diamine and Mannich condensates of phenols, formaldehyde and dialkanolamines and melamine used.

The polyether alcohols have a functionality of preferably 3 to 8 and hydroxyl numbers of preferably 100 mgKOH / g to 1200 mgKOH / g and especially 120 mgKOH / g to 570 mgKOH / g.

Through the use of difunctional polyols, for example polyethylene glycols and / or polypropylene glycols, having a molecular weight in the range from 500 to 1500 in the polyol component, the viscosity of the polyol component can be adjusted.

The compounds having at least two isocyanate-reactive hydrogen atoms also include the optionally used chain extenders and crosslinkers. The rigid polyurethane foams can be prepared without or with the concomitant use of chain extenders and / or crosslinking agents. To modify the mechanical properties, the addition of difunctional chain extenders, trifunctional and higher functional crosslinking agents or optionally also mixtures thereof may prove to be advantageous. As chain extenders and / or crosslinking agents are preferably used alkanolamines and in particular diols and / or triols having molecular weights less than 400, preferably 60 to 300.

Chain extenders, crosslinkers or mixtures thereof are suitably used in an amount of 1 to 20 wt .-%, preferably 2 to 5 wt .-%, based on the polyol component.

The preparation of the polyurethane foams is usually carried out in the presence of blowing agents. As propellant preferably water can be used which reacts with isocyanate groups with elimination of carbon dioxide. Another commonly used chemical blowing agent is formic acid, which reacts with isocyanate to release carbon monoxide and carbon dioxide. In combination with or in place of the chemical blowing agents, so-called physical blowing agents can also be incorporated. be set. These are compounds which are inert to the starting components and which are usually liquid at room temperature and evaporate under the conditions of the urethane reaction. Preferably, the boiling point of these compounds is below 50 ° C. The physical blowing agents also include compounds which are gaseous at room temperature and are introduced under pressure into or dissolved in the starting components, for example carbon dioxide, alkanes, in particular low-boiling alkanes and fluoroalkanes, preferably, alkanes, in particular low-boiling alkanes and fluoroalkanes. The physical blowing agents are usually selected from the group comprising alkanes and / or cycloalkanes having at least 4 carbon atoms, dialkyl ethers, esters, ketones, acetals, fluoroalkanes having 1 to 8 carbon atoms, and tetraalkylsilanes having 1 to 3 carbon atoms in the alkyl chain, in particular tetramethylsilane. Examples which may be mentioned are propane, n-butane, iso- and cyclobutane, n-, iso- and cyclopentane, cyclohexane, dimethyl ether, methyl ethyl ether, methyl butyl ether, methyl formate, acetone, and fluoroalkanes, which can be degraded in the troposphere and therefore for the ozone layer is harmless, such as trifluoromethane, difluoromethane, 1,1,1,3,3-pentafluorobutane, 1,1,1,3,3-pentafluoropropane, 1,1,1,3,3-pentafluoropropane, 1-chloro-3,3,3-trifluoropropene, 1, 1, 1, 2-tetrafluoroethane, difluoroethane and

1, 1, 1, 2,3,3,3-heptafluoropropane, and perfluoroalkanes such as, C3F8, C4F10, C5F12, C6F14, and C7F17. Particular preference is given to hydrocarbons, preferably pentanes, in particular cyclopentane. The said physical blowing agents can be used alone or in any combination with each other.

In a preferred embodiment of the invention, a mixture of physical and chemical blowing agents may be used. Particularly preferred are mixtures of physical blowing agents and water, especially hydrocarbons and water. Among the hydrocarbons, the pentanes, and especially cyclopentane, are particularly preferred.

The preparation of the polyurethanes may, if necessary, be carried out in the presence of catalysts, flame retardants and customary auxiliaries and / or additives auxiliaries and / or additives.

Further details on starting compounds used can be found, for example, in Kunststoffhandbuch, Volume 7 "Polyurethane", edited by Günter Oertel, Carl-Hanser-Verlag Munich, 3rd edition, 1993. The PU rigid foams are preferably used as a heat-insulating intermediate layer in composite elements and for foaming cavities in refrigeration cabinets, in particular for refrigerators and freezers, and ßenmantel of hot water storage. The products are also suitable for the isolation of heated materials, as engine cover and as pipe shells.

Their use, in particular for the production of composite or sandwich elements, which are constructed of a PU rigid foam and at least one cover layer of a rigid or elastic material such as paper, plastic films, aluminum foil, metal sheets, glass webs or chipboard is known. Also known is the foaming of cavities in household appliances such as refrigerators, such as refrigerators or chests or hot water storage, with PU rigid foam as a thermal insulation. Other applications are insulated pipes consisting of an inner tube made of metal or plastic, a Polyurethanandämmschicht and an outer sheath made of polyethylene. Furthermore, the insulation is possible from large storage containers or transport ships, for example, for storage and transport of liquids or liquefied gases in the temperature range of 160 ° C to - 160 ° C. For this purpose suitable heat and cold-insulating rigid PU foams can be known by reacting organic polyisocyanates with one or more compounds having at least two isocyanate-reactive groups, preferably polyester and / or polyether polyols and usually with the concomitant use of chain extenders and / or crosslinking agents in the presence of propellant - Mittein, catalysts and, where appropriate, auxiliaries and / or additives are produced. With a suitable choice of the structural components in this case PU rigid foams can be obtained with a low thermal conductivity and good mechanical properties. A summary of the production of rigid PU foams and their use as a cover or preferably core layer in composite elements and their application as an insulating layer in the cooling or heating technology has been published in, for example, Polyurethane, Kunststoff-Handbuch, Volume 7, 3rd edition 1993, edited by dr. Günter Oertel, Carl Hanser Verlag, Munich, Vienna.

The invention will be explained in more detail in the following examples.

Polyol Syntheses: Example 1

Preparation of the polyols according to the invention: 2, 3 and 5

Polyol 2

A 250 l pressure reactor with stirrer, jacket heating and cooling, metering devices for solid and liquid substances and alkylene oxides and equipment for nitrogen inertization and a vacuum system was heated to 80 ° C and repeatedly inertized. 18.38 kg of glycerol and 1.26 kg DMEOA were charged and the stirrer in Operation taken. Subsequently, sucrose (191, 6 kg) was added to the reactor and the temperature raised to 95 ° C. The mixture was reacted at 95 ° C with 54.0 kg of propylene oxide. After a postreaction time of 30 minutes, an additional 0.64 kg of DMEOA was added. Then the temperature was increased to 1 12 ° C and added 1 16 kg of propylene oxide. The post-reaction of 3 hours proceeded at 1 12 ° C. The product was stripped for 2 h at 105 ° C (vacuum, nitrogen). There were obtained 352 kg of product with the following parameters

Hydroxyl number 444 mg KOH / g

Viscosity 15300 mPas

Water content 0.013%

pH 9.7

Polyol 3

A 600 l pressure reactor with stirrer, jacket heating and cooling, metering devices for solid and liquid substances and alkylene oxides and equipment for nitrogen inertization and a vacuum system was heated to 80 ° C and repeatedly inertized. 58.2 kg of glycerin and 6.0 kg of dimethylethanolamine were charged to the reactor and the stirrer was put into operation. Subsequently, sucrose (191.6 kg) was added to the reactor and the temperature was raised to 95.degree. The mixture was reacted at 105 ° C with 195.0 kg of propylene oxide. Then the temperature was raised to 1212 ° C and the product was reacted with another 352.7 kg of propylene oxide. The post-reaction of 3 hours proceeded at 1 12 ° C. The remaining propylene oxide was stripped off in a stream of nitrogen. 770 kg of product were obtained with the following parameters.

Hydroxyl number 455 mg KOH / g

Viscosity 14800 mPas

Water content 0.03%

pH 9.8

Polyol 5

A 600 l pressure reactor with stirrer, jacket heating and cooling, metering devices for solid and liquid substances and alkylene oxides as well as devices for nitrogen inversion and a vacuum system was heated to 75 ° C and repeatedly inertized. 47.00 kg of glycerol and 3.09 kg of dimethylethanolamine were charged and the stirrer was put into operation. Subsequently, sucrose (154.75 kg) was added to the reactor and 157.50 kg PO at 75 ° C to 95 ° C added.

After an abreaction of 30 minutes at 105 ° C, another 1.55 kg DMEOA were added and added 254.50 kg PO. The post-reaction of 2 hours ran at 105 ° C. The remaining propylene oxide was stripped in a stream of nitrogen and there were obtained 593 kg of the product.

Hydroxyl number 468 mg KOH / g

Viscosity 21300 mPas

Water content 0.016%

pH 10.2

Example 2:

Preparation of Comparative Polyols: 1 and 4

Polyol 1:

A 50 l pressure reactor with stirrer, jacket heating and cooling, metering devices for solid and liquid substances and alkylene oxides, as well as equipment for nitrogen inertization and a vacuum system was heated to 90 ° C and inertized several times. 2.87 kg of glycerol, 0.188 kg of 48% KOH solution and 0.065 kg of water were charged and the stirrer was put into operation. Subsequently, sucrose (9.48 kg) was added. The temperature was raised to 105 ° C and 7.53 kg were added. After a reaction time of 1 h, the temperature was increased to 1 12 ° C and the remaining PO (19.85 kg) was added. The resulting polyetherol was hydrolyzed with water, neutralized with phosphoric acid, filtered and vacuum stripped. There were obtained 39.1 kg of the product. Hydroxyl number 450 mg KOH / g

Viscosity 19500 mPas

Water content 0.07%

pH 9.2 polyol 4

A 50 l pressure reactor with stirrer, jacket heating and cooling, metering devices for solid and liquid substances and alkylene oxides, as well as equipment for nitrogen inertization and a vacuum system was heated to 90 ° C and inertized several times. 4.00 kg of glycerol, 0.245 kg of 48% KOH solution and 0.049 kg of water were introduced and the stirrer was put into operation. Subsequently, sucrose (13.16 kg) was added and 1, 7 kg of PO were added at 105 ° C added. After a post-reaction of 3 h, the temperature was increased to 1212C and the residual PO (22.3 kg) was added. The resulting polyetherol was hydrolyzed with water, neutralized with phosphoric acid, filtered and vacuum stripped. 41.5 kg of the product were obtained.

Hydroxyl number 477 mg KOH / g Viscosity 22300 mPas

Acid number 0.012 mg KOH / g

Water content 0.023%

pH 10.2

methods:

Viscosity measurements: The viscosity of the polyols and of the polyol mixtures was, unless stated otherwise, at 25 ° C. using a Rheotec RC 20 rotational viscometer using the spindle CC 25 DIN (spindle diameter: 12.5 mm, measuring cylinder inner diameter: 13.56 mm) at a shear rate of 50 1 / s. hydroxyl

The hydroxyl numbers were determined according to DIN 53240.

Thermal conductivity:

The thermal conductivity was determined according to DIN 52616. To prepare the test specimens, the polyurethane reaction mixture was poured into a shape of the dimensions 200 × 20 × 5 cm (10% overfilling) and after a few hours a test specimen of dimension 20 × 20 × 2 cm from the Middle cut.

Compressive strength:

The compressive strength was determined according to DIN 53421 / DIN EN ISO 604. Determination of the pentane solubility:

50 g of the polyol or polyol mixture are placed in a 100 ml glass jar. This is done by adding a lot of cyclopentane. Thereafter, the glass vessel is sealed, shaken vigorously for 5 minutes and then allowed to stand for one hour. Thereafter, the appearance of the sample is examined. If the sample is clear, the experiment is repeated with more cyclopentane. If the mixture is cloudy, the experiment is repeated with less cyclopentane. In this way, the maximum soluble amount of cyclopentane in the polyol or in the polyol mixture is determined. This amount is the pentane solubility of the polyol or polyol mixture. The accuracy of this method is 1%.

Foam production for mechanical testing: The following basic formulation was used to carry out the foaming experiments: 100 parts by weight Polyol (or polyol mixture)

2.4 parts by weight Stabilizer (Tegostab® B 8467 from Evonik)

0.85% by weight of water

dimethylcyclohexylamine

cyclopentane

Polymer MDI (Lupranat M20® from BASF SE)

The foams are produced at an isocyanate index of 100. The amounts of dimethylcyclohexylamine and cyclopentane were so dimensioned that in a beaker test with a total weight of 50 g and with a stirring time of 10 s and a setting time of 55 s, a free-foamed bulk density of 35 g / l was achieved. In a second experiment, the components were thoroughly mixed by means of a laboratory stirrer and made to foam in a cube-shaped steel mold (500 g reaction mixture, volume of the mold: 1 1, 4 L). The fully reacted foam samples were removed from the mold after 20 min and stored under standard conditions for a further 3 days. The determination of the density was carried out according to ISO 845, the determination of the compressive strength according to ISO 604.

Table 1 gives an overview of the polyols used. Table 1: Overview of the polyols used and pentane solubilities

(V = Comparison Examples)

Polyol structure, catalysis OH number pentane viscosity average functionality solubility

[mg KOH / g] [%] [mPas]

1 (V) sucrose / glycerol / PO, KOH 450 8 19500

Fn = 5.1

2 sucrose / glycerol / PO, DMEOA 444 13 15300

Fn = 5.1

3 sucrose / glycerin / PO, DMEOA 455 13 14800

Fn = 5.2

4 (V) sucrose / glycerol / PO, KOH 477 10 22300

Fn = 5.1

5 sucrose / glycerol / PO, DMEOA 468 11 21300

Fn = 5.1

6 dipropylene glycol KOH 837 Not relevant n.r.

(No.)

7 glycerol / PO KOH 230 no 8 TDA / EO / PO KOH 160 no

Fn: medium functionality

Table 2 presents a comparison of the properties of a sucrose-polyol based system.

Table 2: Foam formulations based on sucrose-based polyols

(V = Comparison Example)

Parts by weight

Tables 3 and 4 give an overview of the systems obtained with polyol blends.

Table 3: Foam formulations based on polyol mixtures in which saccharose-based polyols are the main constituent of the mixture (V = comparative example)

3 (V) 4

Polyol 1 [wt.T.I.] 65

Polyol 2 [wt.T.I.] 65

Polyol 7 [w / w] 27 27

Polyol 6 [w / w] 8 8

Dimethylcyclohexylamine [wt.T.I.] 5.2 4.0

Cyclopentane [wt.TI.] 14.5 13.6

Pentane solubility of the mixture [%] 21 23

Viscosity of the mixture [mPas] 2690 2300

cup test

Thread pulling time [s] 52 56 Bulk density [kg / m ³ ] 35.2 35.6

cube

Compressive strength [N / mm ² ] 0.24 0.23

Core density [kg / m ³ ] 36.1 37.0

Table 4: Foam formulations based on polyol mixtures in which saccharose-based polyols are the main constituent of the mixture

(V = Comparison Examples)

Comment to Tables 2-4:

The amine-catalyzed polyols show better utilization of the cyclopentane used as blowing agent. With a smaller amount of cyclopentane, a foam with the same density can thus be produced. Due to the autocatalytic properties of the amine-catalyzed polyols, the amount of catalyst used can be reduced. Improved pentane solubility and lower viscosity were evident not only with the exclusive use of amine-catalyzed polyols (Table 2) but also with blends containing such polyols (Tables 3 and 4). The mechanical properties are the same.

Machine foaming: From the indicated raw materials a polyol component was produced. In a high-pressure Puromat ^® HD30 (Elastogran GmbH), the polyol was mixed with the required amount of the specified isocyanate, so that an isocyanate Index of 1 10 was reached. The reaction mixture was injected into molds measuring 200 cm × 20 cm × 5 cm or 40 × 70 cm × 9 cm and allowed to foam there. The properties and characteristics of the foams are given in Tables 5 and 6.

Table 5: Foam composition for machine foaming

9 (V) 10

Polyol 1 [parts by weight] 63.45 -

Polyol 3 [parts by weight] - 63.45

Polyol 8 [parts by weight] 25.00 25.00

Polyol 6 [parts by weight] 5.00 5.00

Silicone stabilizer [parts by weight] 2.00 2.00

Polycat 8 (Air Products) [by weight] 0.60 0.60

Polycat 5 (Air Products) [parts by weight] 0.90 0.90

Polycat 41 (Air Products) [by weight] 0.55 0.55

Water [by weight] 2.50 2.50

Cyclopentane / isopentane (70/30) [parts by weight] 13.00 13.00

Table 6: Properties

The determination of the post-mortem was carried out with the help of a box shape of dimension 70 x 40 x 9 cm depending on the demolding time and the overfilling (OP = Overpacking) by height measurement of the boxes after 24 h. The surface quality was determined visually by determining the frequency and intensity of surface disturbances (0 = reference, + = lower number of perturbations and lower intensity of surface perturbations, see reference).

Summary of Results Comments on Tables 5 and 6:

Despite the same functionality and OH number, the viscosity of the DMEOA-catalyzed polyol is lower by 3000 mPas. This is significant and also manifests itself in a likewise lower viscosity of the polyol component and in the flow factor and an improved surface quality (reduced voids rate). All other properties which are important for rigid foams of this application are comparable.

Claims

claims

1 . Process for the preparation of rigid polyurethane foams by reacting a) polyisocyanates with b) compounds having at least two isocyanate-reactive hydrogen atoms in the presence of c) blowing agents, characterized in that the compounds having at least two isocyanate-reactive hydrogen atoms b) at least one polyether alcohol b1 ) having a functionality of 2-8 and a hydroxyl number of 200-800 mgKOH / g, by addition of alkylene oxides b1 b) to compounds having at least two alkylene oxides reactive hydrogen atoms b1 a), hereinafter also referred to as starter substances, using an amine b1 c) was prepared as a catalyst.

2. The method according to claim 1, characterized in that the polyether alcohol b1) in an amount of 10-90 wt .-%, based on the weight of component b) is used.

3. The method according to claim 1, characterized in that for the preparation of the polyether alcohol b1) as compounds having at least two reactive with alkylene oxides hydrogen atoms b1 a) mixtures are used which contain at least one compound bl ai), which is solid at room temperature.

4. The method according to claim 1, characterized in that the compound bl ai) is selected from the group comprising pentaerythritol, glucose, sorbitol, mannitol, sucrose, polyhydric phenols, resols, condensates of aniline and formaldehyde, toluenediamine, Mannich Condensates of phenols, formaldehyde and dialkanolamines, melamine and mixtures of at least two of the listed compounds.

5. The method according to claim 1, characterized in that the compound bl ai) is selected from the group containing sucrose, sorbitol and pentaerythritol.

6. The method according to claim 1, characterized in that for the preparation of the polyether alcohol b1) as compounds having at least two with alkylene oxides Reactive hydrogen atoms b1 a) mixtures are used which contain at least one compound bl aii), which is liquid at room temperature.

7. The method according to claim 1, characterized in that the compound b1 aii) is selected from the group comprising glycerol, monofunctional alcohols having 1-20 carbon atoms, ethylene glycol and its higher homologues and propylene glycol and its higher homologues, hydroxyalkylamines, such as mono- ethanolamine, diethanolamine, triethanolamine, and their reaction products with propylene oxide.

8. The method according to claim 1, characterized in that the compound b1 a) contains a mixture of at least one compound bl ai), which is solid at room temperature, and at least one compound bl aii), which is liquid at room temperature.

9. The method according to claim 1, characterized in that as the catalyst b1 c) an amine of bl ai) different amine is used.

10. The method according to claim 1, characterized in that the catalyst b1 c) is selected from the group comprising trialkylamines, aromatic amines, pyridine, imidazoles, guanidines, alkylated guanidines, amidines.

1 1. A method according to claim 1, characterized in that the catalyst b1 c) dimethylethanolamine.

12. The method according to claim 1, characterized in that the catalyst b1 c) imidazole.

13. The method according to claim 1, characterized in that the catalyst b1 c) for the preparation of component b1) in an amount of 0.01 - 5.0, preferably

0.05-3.0 and more preferably 0.1-1.0% by weight, based on the total batch.

14. The method according to claim 1, characterized in that hydrocarbons are used as blowing agent.

15. rigid polyurethane foams, producible according to one of claims 1 -14.