HK1162558A - Method for producing polyester polyols having low amounts of dioxane waste - Google Patents

Description

Process for preparing polyester polyols with low levels of di  alkane waste

The invention relates to the production and use of polyester polyols which are synthesized from at least one carboxylic anhydride and diethylene glycol, the formation of 1, 4-diethylene glycol from diethylene glycol being largely suppressed by means of special reaction controlAn alkane.

Polyester polyols are an important component of many foamed and non-foamed polyurethane systems. Most polyester polyols used to form polyurethanes have terminal hydroxyl groups available for further reaction with isocyanate groups. The molar mass of the polyester polyols is generally in the range of 200 and 5000 daltons. They are mainly prepared by polycondensation of polycarboxylic acids, especially dicarboxylic acids, and polyols, especially diols, with the carboxyl and hydroxyl groups reacting under dehydrating conditions to form ester groups. Anhydrides of polycarboxylic acids such as phthalic anhydride may also be used as an alternative.

The dehydration conditions can be achieved, for example, by: vacuum is applied and the water of reaction is blown off with a stream of inert gas or azeotropic blowing is carried out with entrainers (Houben-Weyl, Methoden der organischen Chemie, Vol. 14/2, Makromolekulare Stoffe, Thieme Verlag Stuttgart, codified by E.M. muller, pp. 1-47, 1963).

It is known to the person skilled in the art that in the esterification of aromatic phthalic acids, which are mostly used in the form of phthalic anhydride, with diethylene glycol, 1, 4-dioxane is formed as a by-product in an undesirable manner. In the case of preparation in an industrial setting, the di-s to be formedThe alkane is discharged together with the reaction water and then has to be decomposed, for example, in a sewage treatment plant or incinerated after concentration. This additional processing step adds to the cost of the polyester polyol preparation.

1, 4-bis formed as a by-productThe alkane also acts to reduce the yield of the desired product, since part of the diethylene glycol used is not incorporated into the polyester formed, but is 1, 4-diethylene glycol as described aboveThe alkane leaves the reaction mixture as it is. Thus, 1, 4-bisThe formation of alkanes leads to serious economic disadvantages.

In addition, 1, 4-bis that the production apparatus can allowThe amount of alkane is limited by the permissive conditions. In these cases, two is usedThe limitation of the amount of alkane in turn indirectly leads to a limitation of the production capacity of the plant for preparing the polyester polyol.

It is therefore an object of the present invention to provide a process for the synthetic preparation of polyester polyols from at least one carboxylic anhydride and diethylene glycol which overcomes the disadvantages of the prior art.

It is an object of the present invention, in particular, to limit the amount of diethylene glycol relative to the amount of at least one carboxylic anhydride and diethylene glycol used in the preparation of polyester polyolsThe amount of alkane produced. In this way, two can be put togetherThe amount of alkane is limited to less than 7 g/kg of diethylene glycol, preferably less than 5 g/kg of diethylene glycol.

It is a further object of the present invention to reduce the amount of diester polyols formed in the preparation of polyester polyols from at least one carboxylic anhydride and diethylene glycol relative to the amount of polyester polyol formedThe amount of alkane produced. In this way, two can be put togetherThe amount of alkane is limited to less than 4 g/kg polyester polyol, preferably less than 3 g/kg polyester polyol.

The above object is achieved by a method for preparing a polyester polyol, comprising the steps of:

a) at least one carboxylic anhydride (A) and diethylene glycol (B) are mixed together and reacted,

wherein the molar ratio of component (B) to (A) is in the range from 1.5: 1.0 to 0.7: 1.0, the ratio of components (A) and (B) relative to the weight of all components of the mixture is in the range from 66 to 90% by weight,

b) adding diethylene glycol (B) to the polyester polyol of step a),

wherein the molar mass of the polyester polyol of step a) is greater than the molar mass of the polyester polyol of step b),

characterized in that, in step a), at least one further C is added₂-C₄Diol (C) (excluding diethylene glycol) and at least one aliphatic C₅-C₁₂Dicarboxylic acid (D) or at least one C₅-C₁₀A diol (E) and at least one C₄A dicarboxylic acid (F).

The amounts of components (C), (D), (E) and (F) in step a) are chosen such that the sum of the amounts of all components (A), (B), (C) and (D), or (E) and (F) in the mixture is 100% by weight.

In a preferred embodiment, the carboxylic anhydride (A) is aromatic.

The carboxylic anhydride (A) is preferably selected from phthalic anhydride, trimellitic anhydride and pyromellitic anhydride. The carboxylic acid anhydride is particularly preferably phthalic anhydride.

By replacing a small amount of an aromatic dicarboxylic acid with an equivalent amount of an aliphatic dicarboxylic acid (D or F) and replacing a small amount of diethylene glycol with an equivalent amount of a diol (C) or (E), the di-glycol produced during the preparation of the polyester polyol is caused to react withThe amount of alkane waste is reduced, far beyond what would be expected as a result of the dilution effect. The properties of the polyester polyols prepared remain virtually the same, in other words the properties of the polyester polyols prepared by the process according to the invention are the same as those of the corresponding polyols prepared without addition of the aliphatic dicarboxylic acid (D or F) and without addition of the diol (C) or (E).

C₂-C₄The diol (C) is preferably selected from ethylene glycol, 1, 3-propanediol, 2-methyl-1, 3-propanediol, 1, 2-propanediol. C₂-C₄The diol (C) is particularly preferably ethylene glycol.

Aliphatic C₅-C₁₂Dicarboxylic acids(D) Preferably from glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid and dodecanedioic acid. Adipic acid or sebacic acid are particularly preferred C₅-C₁₂A dicarboxylic acid (D).

C₅-C₁₀The diol (E) is preferably selected from the group consisting of 1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 1, 6-hexanediol and 1, 8-octanediol. C₅-C₁₀The diol (E) is particularly preferably 3-methyl-1, 5-pentanediol or 1, 6-hexanediol.

C₄The dicarboxylic acid (F) is preferably selected from succinic acid, fumaric acid and maleic acid. C₄The dicarboxylic acid (F) is particularly preferably succinic acid.

The addition of diethylene glycol (B) in step B) and equilibration with the polyester is preferably carried out in such a way that the distribution of the individual oligomers of the polyester polyol conforms to the Flory oligomer distribution equation (P.J. Flory, Principles of Polymer Chemistry, Cornell University Press, Ithaca 1953, p.317 and beyond). The polyester polyols of a given class in the Flory balance always have the same oligomer distribution, and therefore give consistent material properties for polyurethane materials made therefrom.

In step B), the addition of diethylene glycol (B) is carried out under any temperature conditions of the intermediate of step a) and of the diethylene glycol to be added. The temperature of the diethylene glycol to be added is preferably from room temperature to 60 ℃ and the intermediate of step a) is at an elevated temperature of 120 ℃ to 200 ℃. Diethylene glycol (B) is added under laboratory conditions in countercurrent to nitrogen, preferably by applying a vacuum to the reactor under industrial conditions. The amount of diethylene glycol (B) to be added is determined by the OH number of the product of step a), the OH number of the desired end product, and the batch size, according to the following equation (1):

the amount of diethylene glycol (B) to be added (in g) ═ (Z-Y) × M/(1053-Z) (1)

Wherein:

z represents the target OH value after step b),

y represents the OH number of step a),

m represents the amount of the polyester polyol of step (A), and

the value 1053 corresponds to the OH value of diethylene glycol.

The addition of diethylene glycol (B) can be carried out dispersedly in a continuous, homogeneous or heterogeneous manner over a prolonged period of time, for example over 1 to 5 hours, or else in one portion.

In step a), the molar ratio of (B) to (A) is preferably in the range from 1.2: 1.0 to 0.75: 1.0.

The molar mass of the hydroxyl-terminated polyester polyols obtained in step a) is preferably in the range from 1400-430 g/mol, particularly preferably in the range from 1120-490 g/mol.

The OH number of the polyester polyols obtained in step a) is preferably in the range from 80 to 260 mg KOH/kg, preferably in the range from 100 to 230 mg KOH/kg. In this context, both the OH number and the molar mass of step a) are theoretical OH numbers or theoretical molar masses resulting from the materials used in step a), based on the following assumptions, namely: neither form twoThe alkane, also did not expel free monomeric low molecular weight diol from the reaction batch.

The molar mass of the polyester polyol obtained in step b) is preferably in the range from 750-350 g/mol, particularly preferably in the range from 620-370 g/mol.

The OH number of the polyester polyol obtained in step b) is preferably in the range from 150-320 g KOH/kg, preferably in the range from 180-300 g KOH/kg.

The OH value was determined by: the terminal hydroxyl groups are first reacted with a defined excess of anhydride (e.g. acetic anhydride), the excess anhydride is hydrolyzed in the polyester polyol sample, and the free carboxyl group content is determined by direct titration with a strong base (e.g. sodium hydroxide). The difference between the carboxyl groups introduced in the form of anhydrides and the carboxyl groups determined experimentally is a measure of the number of hydroxyl groups in the sample. The OH value is obtained if this value is corrected by the number of carboxyl groups contained in the original sample as a result of incomplete esterification, i.e. by the acid value. The titration, which is carried out predominantly with sodium hydroxide, is converted into equivalents of potassium hydroxide, the acid and hydroxyl values then being given in units of g KOH/kg. Herein, the following mathematical relationship exists between the hydroxyl number (OH #) and the number average molecular weight (M):

M＝(56100*F)/OH#

herein, F denotes the number average functionality (functionality is related to the number of hydroxyl groups per molecule, also referred to as hydroxyl functionality). The hydroxyl functionality can generally be calculated by the formula used to prepare the polyester polyol.

The viscosity of the polyester polyol obtained in step b) at a temperature of 50 ℃ is in the range of 400-3000mPas, preferably in the range of 450-1500 mPas.

The viscosity is determined using a cone/plate viscometer (e.g., Physica MCR 51 from emp corporation (Anton Paar), extrapolated to zero shear rate). The polyols of the present invention should have the greatest degree of non-pseudoplasticity possible.

The proportion of the components (A) and (B) is preferably in the range of 66 to 90% by weight, particularly preferably in the range of 70 to 85% by weight, relative to the weight of all the components.

The acid number of the polyester polyol obtained in step b) is in the range of 0.5 to 3.5 mg KOH/g.

The functionality F of the polyester polyols obtained in step b) is preferably in the range from 1.9 to 3. Functionalities greater than 2 are obtained by incorporating a small amount of structural units having a functionality greater than 2, such as triols or tetraols and/or tricarboxylic acids or tetracarboxylic acids and/or trifunctional hydroxycarboxylic acids, during the esterification. Typical representatives are glycerol, 1, 1, 1-trimethylolpropane, pentaerythritol, trimellitic acid, trimesic acid, malic acid, tartaric acid, citric acid, dimethylolpropionic acid, etc. By using glycerol or 1, 1, 1-trimethylolpropane, functionalities F in the range of 2.0 to 2.3 can preferably be obtained. In this context, the viscosity measured at 25 ℃ deviates by less than 20% from the viscosity value measured for certain polyester polyols which have the same functionality and whose hydroxyl value, with the exception of the functionality-increasing component (e.g.1, 1, 1-trimethylolpropane), is synthesized exclusively from phthalic anhydride and diethylene glycol.

In the preparation of the polyester polyols according to the invention, preference is given to using a vacuum process at a pressure in the range from normal pressure up to a vacuum limit of 5 mbar, preferably up to a vacuum limit of 10 mbar, and at a temperature in the range from 100 ℃ to 230 ℃ and preferably 180 ℃ to 215 ℃.

The process according to the invention for preparing polyester polyols is preferably carried out in the following manner: all components of step a) are simultaneously prepared by first condensing them at normal pressure at a temperature in the range from 100 ℃ and 230 ℃ and particularly preferably at a temperature in the range from 180 ℃ and 215 ℃ using a protective gas until no more reaction water is distilled off, then reducing the pressure to less than 20 mbar within a period of from 1 to 4 hours, during which an esterification catalyst is optionally added, and finally carrying out the polycondensation at a temperature in the range from 180 ℃ and 215 ℃ under a completely water-jet vacuum until an acid number of less than 5 g KOH/kg is obtained.

All catalysts known to the person skilled in the art can be used for the preparation of the polyester polyols according to the invention. Preference is given to using tin (II) chloride and titanium tetraalkoxides.

The reaction of the components for the preparation of the polyester polyols according to the invention is preferably carried out in bulk.

Polyester polyols can also be prepared by the nitrogen-blown method, in which the condensates are discharged from the reaction vessel by a nitrogen stream (J.H.Saunders and H.T.Frisch, polyurethane: Chemistry and Technology, Part I.chemistry, Chemistry (Polyurethanes: Chemistry and Technology), Interscience (Interscience published by John Wiley and Sons), New York (New York), 1962, page 45).

The invention also provides a process for preparing a PUR/PIR foam, which comprises the steps of:

reacting:

a) the polyester polyol obtained by the above-mentioned method,

b) a component comprising a polyisocyanate, wherein the polyisocyanate is,

c) a blowing agent,

d) one or more catalysts selected from the group consisting of,

e) optionally flame retardants and/or other auxiliary substances and additives.

The polyisocyanate containing component includes a polyisocyanate.

The polyisocyanates used are those conventionally used in the polyurethane field. Suitable examples are generally aliphatic, cycloaliphatic, araliphatic and aromatic polyvalent isocyanates. Aromatic diisocyanates and polyisocyanates are preferably used. Preferred examples are 2, 4-and 2, 6-tolylene diisocyanate and mixtures of these isomers, 2, 2 '-diphenylmethane diisocyanate, 2, 4' -and 4, 4 '-diphenylmethane diisocyanate and any mixtures of these isomers, 2, 2' -diphenylmethane diisocyanate, 2, 4 '-diphenylmethane diisocyanate, 4' -diphenylmethane diisocyanate (binuclear) and mixtures of polyphenylene-polymethylene polyisocyanates (MDI). Mixtures of toluene diisocyanate and MDI may also be used.

Generally known compounds having a chemical or physical action may be used as the blowing agent. Water is preferably used as a chemically acting blowing agent. Examples of physical blowing agents are (cyclo) aliphatic hydrocarbons having 4 to 8 carbon atoms, and HFCs and HCFCs, which evaporate under the conditions of polyurethane formation. In a preferred embodiment, pentane and cyclopentane and mixtures of pentane and cyclopentane are used as blowing agents.

The amount of blowing agent used is determined to a large extent by the desired density of the foam. The amount of water used is generally 0 to 5% by weight, preferably 0.1 to 3% by weight, relative to the finished formulation. Physical blowing agents can also be used in general, in amounts of from 0 to 8% by weight, preferably from 0.1 to 5% by weight. Carbon dioxide may also be used as a blowing agent, preferably carbon dioxide is dissolved as a gas in the starting components.

Conventional and known polyurethane or polyisocyanurate forming catalysts are used as catalysts for preparing the polyurethane or polyisocyanurate foams according to the invention, for example organotin compounds, such as tin diacetate, tin dioctoate, dibutyltin dilaurate, and/or strongly basic amines, such as 2, 2, 2-diazabicyclooctane, triethylamine, or preferably triethylenediamine or bis (N, N-dimethylaminoethyl) ether, as well as potassium acetate and aliphatic quaternary ammonium salts, for catalyzing the PIR reaction.

The catalyst is preferably used in an amount of 0.1 to 3% by weight, preferably 0.5 to 2% by weight, relative to the total weight of all components.

The reaction of the above-mentioned components is optionally carried out in the presence of auxiliary substances and/or additives, for example cell regulators, release agents, pigments, reinforcing materials such as glass fibers, surface-active compounds and/or stabilizers, in order to prevent oxidation, thermal degradation, hydrolytic degradation or microbial degradation or aging. The polyurethane foam generally has a density of from 20 to 250 g/l, preferably from 25 to 150 g/l, particularly preferably from 30 to 100 g/l, most particularly preferably from 35 to 75 g/l.

For the preparation of the polyurethane foams according to the invention, all components are generally mixed using conventional high-pressure or low-pressure mixing heads and reacted in such amounts that, for the case of pure PUR foams, the equivalent ratio of NCO groups to the sum of the reactive hydrogen atoms is in the range from 0.80: 1.00 to 1.60: 1.00, preferably in the range from 0.90: 1.00 to 1.15: 1.00. In this context, a ratio of 1.00: 1.00 corresponds to an NCO index of 100.

In the case of PUR/PIR foams, the equivalent ratio of the sum of the NCO groups to the reactive hydrogen atoms is in the range from 1.60: 1.00 to 5.00: 1.00, preferably from 2.00: 1.00 to 4.00: 1.00.

The invention also provides the use of the polyester polyols prepared by the above process for the preparation of polyurethanes. Polyurethane is a versatile material that is used in many fields. Since a wide variety of raw materials can be used, products having various properties, such as a rigid foam for insulation, a soft block foam for a mattress (slabstock foams), a soft molded foam for an automobile seat and a seat cushion, a sound-absorbing foam for sound insulation, a thermoplastic foam, a foam for shoes or a microcellular foam, and a compression-cast system and a thermoplastic polyurethane, can be prepared.

The invention also provides the use of the PUR/PIR foam produced by the above-described process for producing a metal composite element.

The metal composite element is a sandwich-like element consisting of at least two outer layers and a core layer therebetween. In particular, the metal-foam composite element is composed of at least two outer metal layers and one core layer comprising a foam material, such as a rigid Polyurethane (PUR) foam material or a rigid polyurethane/polyisocyanurate (PUR/PIR) foam material. These metal-foam composite elements are known from the prior art and are also referred to as metal composite elements. Other layers may be provided between the core layer and the outer layer. The outer layer may be coated, for example with a lacquer.

Examples of applications for these metal composite elements are flat or lined wall elements and profiled roof elements for the construction of factory buildings and cold stores, and elements for truck bodies, factory doors or shipping containers.

The production of these metal composite elements can be carried out continuously or discontinuously. Apparatuses for continuous production are known, for example from DE 1609668A or DE 1247612A.

In a further embodiment of the process according to the invention, the proportion of polyester polyol A1) contained in the polyol component A) is from ≥ 60 to ≤ 70 parts by weight, the proportion of polyether polyol A2) is from ≥ 1 to ≤ 10 parts by weight, and the proportion of polyester polyol A3) is from ≥ 1 to ≤ 5 parts by weight. Such polyol formulations can be used to prepare flexible foams having satisfactory adhesion and good dimensional stability.

An example of a formulation for the polyol component a) in the process according to the invention is:

polyester polyol a 1): more than or equal to 60 and less than or equal to 70 parts by weight

Polyether polyol a 2): more than or equal to 1 and less than or equal to 10 parts by weight

Polyester polyol a 3): more than or equal to 1 and less than or equal to 5 parts by weight

Flame retardant TCPP: more than or equal to 15 and less than or equal to 25 parts by weight

Flame retardant TEP: more than or equal to 1 and less than or equal to 5 parts by weight

Silicone containing stabilizers: more than or equal to 2 and less than or equal to 8 parts by weight

Carboxylate (PIR catalyst): more than or equal to 3 and less than or equal to 10 parts by weight

Foaming agent: n-pentane

The invention also relates to polyurethane/polyisocyanurate foams obtainable by the process according to the invention. To avoid unnecessary repetition, reference is made to the description of the method according to the invention with regard to the details of the individual embodiments.

The foam material according to the invention can be used in the following form, for example: in the form of a rigid foam for insulation, in the form of a flexible slabstock foam for mattresses, in the form of a flexible molded foam for car seats and seat cushions, in the form of a sound-absorbing foam for sound insulation, as a thermoplastic foam, as a foam for shoes or as a microcellular foam.

In one embodiment of the polyurethane/polyisocyanurate foams according to the invention have a density of from ≥ 30 kg/m to ≤ 50 kg/m. The density was determined in accordance with DIN EN ISO 3386-1-98. The density is preferably in the range from ≥ 33 kg/cubic meter to ≤ 340 kg/cubic meter, particularly preferably ≥ 35 kg/cubic meter to ≤ 38 kg/cubic meter.

The metal composite element is a sandwich-like element consisting of at least two outer layers and a core layer therebetween. In particular, the metal-foam composite element comprises at least one outer metal layer and one core layer comprising a foam material, such as a rigid Polyurethane (PUR) foam material or a rigid polyurethane-polyisocyanurate (PUR-PIR) foam material. These metal-foam composite elements are known from the prior art and are also referred to as metal composite elements. Suitable metals are, for example, steel and aluminum.

Examples of applications for these metal composite elements are flat or lined wall elements and profiled roof elements for the construction of factory buildings and cold stores, and elements for truck bodies, factory doors or shipping containers.

The production of these metal composite elements can be carried out continuously or discontinuously. Apparatuses for continuous production are known, for example from DE 1609668 or DE 1247612.

Total Smoke Generation TSP of Metal composite elements prepared Using polyurethane/polyisocyanurate (PUR/PIR) foams according to the invention after 600 seconds₆₀₀For example, 45 square meters to 60 square meters. TSP₆₀₀The value can also be more than or equal to 46 square meters and less than or equal to 58 square meters or more than or equal to 47 square meters and less than or equal to 55 square meters. Furthermore, according to EN 13823, the smoke-generating SMOGRA values of these metal composite components are ≥ 1m²/s²To less than or equal to 10m²/s²Preferably ≧ 2m²/s²To less than or equal to 8m²/s²Particularly preferably ≥ 3m²/s²To less than or equal to 6m²/s²。

The invention also provides a metal composite element comprising a metal layer and a layer comprising a polyurethane/polyisocyanurate foam according to the invention. More details regarding the metal composite components have been provided with respect to the use of the foam material according to the present invention.

In one embodiment of the metal composite component according to the invention, its total smoke generation value TSP after 600 seconds₆₀₀Is more than or equal to 45 square meters and less than or equal to 60 square meters, preferably more than or equal to 46 square meters and less than or equal to 58 square meters, and particularly preferably more than or equal to 47 square meters and less than or equal to 55 square meters.

In another embodiment of a metal composite component according to the invention, the smoke generation SMOGRA value is ≧ 1m²/s²To less than or equal to 10m²/s²Preferably ≧ 2m²/s²To less than or equal to 8m²/s²Particularly preferably ≥ 3m²/s²To less than or equal to 6m²/s²。

Determination of the SMOGRA and TSP values according to Standard EN 13823₆₀₀Value, THR₆₀₀Values and FIGRA values.

The present invention will be described more specifically with reference to examples.

Examples

Composition of the raw materials used in the examples

Phthalic Anhydride (PA): technical PA from Lanxess Deutschland GmbH

Adipic acid: adipic acid from BASF

Diethylene glycol (DEG): DEG from million nice company (Ineos)

Ethylene Glycol (EG): EG from million nice Co (Ineos)

Tin (II) chloride dihydrate: from Aldrich (Aldrich)

The analytical methods used were:

viscometer: MCR 51 from Enpu corporation (Anton Paar)

A) Preparation of polyester polyols

Example 1(single step standard method, comparative):

1437.1 grams (9.71 moles) of PA were placed in a 4 liter four neck flask equipped with a heating mantle, mechanical stirrer, internal thermometer, 40 cm packed column, distillation head, descending jacketed coil condenser, dry ice cooled receiver, and septum vacuum pump at 140 ℃ under nitrogen protection, and 1737.3 grams (16.39 moles) of diethylene glycol was added slowly. After 1 hour, the temperature was raised to 180 ℃ and 65 mg of tin (II) chloride dihydrate were added with stirring and the pressure was reduced to 700 mbar. The pressure was continuously reduced to a limit value of 45 mbar for a further period of 5 hours. The temperature was raised to 200 ℃ and the pressure to 115 mbar, the reaction was complete and the total operating time was up to 27 hours. During the reaction, the distillate was collected in a receiver cooled with dry ice. Determination of the formation of 1, 4-bisThe amount of alkane was 17.6 g.

Analysis of the polyester:

hydroxyl value: 234 mg KOH/g

Acid value: 1.6 mg KOH/g

Viscosity: 11300mPas (25 deg.C), 930mPas (50 deg.C), 190mPas (75 deg.C)

Amount of polyester polyol formed: 2982 g

Relative to the amount of polyester polyol, bisAmount of alkane: 17.6 g/2.982 kg-5.92 g diAlkane per kilogram polyester

Relative to the amount of diethylene glycol used, twoAmount of alkane: 17.6 g/1.738 kg-10.16 g diAlkane per kilogram diethylene glycol

Example 2(two-step Process, according to the invention)

1444 g (9.76 mol) of PA are placed in the apparatus according to example 1 at 180 ℃ under nitrogen protection, and 1193 g (11.26 mol) of diethylene glycol are added slowly. After 1 hour, the temperature was lowered to 150 ℃. 356 g (2.44 mol) of adipic acid and 429 g (6.92 mol) of EG were added, and the mixture was reacted at 200 ℃ for 3 hours. 65 mg of tin (II) chloride dihydrate were added and the pressure was reduced to 300 mbar. The reaction was completed by continuously reducing the pressure to the limit of 80 mbar for a further period of 5 hours, the total operating time being at most 21 hours. During the reaction, the distillate was collected in a receiver cooled with dry ice. Determination of the 1, 4-bis formed by gas chromatographyThe amount of alkane was 4.8 g, and the hydroxyl value was 199 mg KOH/g (calculated: 212 mg KOH/g); 160 g (1.51 mol) of diethylene glycol are added and the mixture is equilibrated at 200 ℃ for 5 hours under normal pressure.

Analysis of the polyester:

hydroxyl value: 239.7 mg KOH/g

Acid value: 2.1 mg KOH/g

Viscosity: 8700mPas (25 ℃ C.), 820mPas (50 ℃ C.), 180mPas (75 ℃ C.)

Amount of polyester polyol formed: 3315 g

Relative to the amount of polyester polyol, bisAmount of alkane: 4.8 g/3.315 kg-1.45 g diAlkane per kilogram polyester

Relative to the amount of diethylene glycol used, twoAmount of alkane: 4.8 g/1.353 kg-3.55 g diAlkane per kilogram diethylene glycol

The following terminology is used:

"theoretical mass of ester" means the theoretical yield of polyester polyol calculated from the amount of starting materials (excluding side reactions).

"has no twoThe ester mass of the alkane "means the amount of the polyester polyol obtained as determined by experiment.

Table 2: comparative example 6 and example 7 according to the invention, the hydroxyl number of the polyester polyol was 280-300 mg Range of KOH/gram.

In each case, 20ppm of tin (II) chloride dihydrate were used as catalyst.

DEG diethylene glycol and PA phthalic anhydride

As can be seen from tables 1 and 2, by using the process according to the invention, the formation of di-s can be significantly reducedThe amount of alkane. Thus, using the standard method according to comparative example 6, for example, 5.40 g of bis are produced per 1 kg of polyester polyol formedAlkane, or 8.83 g of diethylene glycolAlkane, whereas in example 7 according to the invention only 0.81 g of bis are produced per 1 kg of polyester polyol formedAlkane, or 2.18 g of di-ethylene glycol per 1 kg of diethylene glycol usedAn alkane.

The variables listed in table 1 differ significantly from the examples in table 2 in the OH number of the polyester polyol, but the effect of both has the same properties.

B. Examples of the preparation of rigid PUR/PIR foams：

Examples 8 to 10：

The components used：

(a) Polyester polyols from comparative example 1(CE1) or from examples 3 and 4 according to the invention.

(b) TCPP, tris (1-chloro-2-propyl) phosphate from Lanxess GmbH, Lanxess, Germany.

(c) TEP, triethyl phosphate, from lewed corporation (levegard).

(d) Additive 1132 from Bayer material science, comprising the reaction product of phthalic anhydride and diethylene glycol having an acid number of about 97 mg KOH/g.

(e) PET V657, a trifunctional polyethylene oxide polyol starting from 1, 1, 1-trimethylolpropane, having a molar mass of about 660 daltons, is available from Bayer Material science AG.

(f) Stabilizers, polyether-polysiloxane copolymers, from the company Evonik (Evonik).

The foam additives (b-f) listed in table 3 comprise 20 parts by weight of component (b), 5 parts by weight of component (c), 2.2 parts by weight of component (d), 5 parts by weight of component (e) and 4 parts by weight of component (f).

Activator (g): carboxylate (PIR catalyst): desmorapidPu 30HB13 from Bayer materials science AG, levirkusen, germany.

Isocyanate (h): desmodurPu 44V70L, polymeric polyisocyanate based on 4, 4' -diphenylmethane diisocyanate, having an NCO content of about 31.5% by weight, from Bayer materials science AG, Leverkusen, germany.

On a laboratory scale, all the raw materials from the rigid foam formulation (except the polyisocyanate component) were weighed into a cardboard container (cardboard maker), heated to 23 ℃, mixed with a Pendraulik laboratory mixer (for example LM-34 from pickers (Pendraulik)), optionally with the addition of a volatile blowing agent (pentane). The polyisocyanate component is then added to the polyol mixture while stirring (similarly heated to 23 ℃), the mixture is mixed vigorously and the reaction mixture is poured into a mould (Corus) having a metal outer layer. After 2.5 minutes, the hardness of the foam was measured using the scoring method and after 8-10 minutes the maximum core temperature was measured. The mixture was allowed to react at 23 ℃ for at least 24 hours more, and then the following properties were measured.

The BVD test corresponds to the Switzerland base test (basic Swiss test) for determining the flammability degree of building materials, published in 1988 by Vereinigung kantonale Feuerversacherung, revised in 1990, 1994, 1995 and 2005 (available from Vereinigung kantonale Feuerversacherung, Bunesstr.20, 3011 Berne, Switzerland).

Adhesion: the force required for peeling using a spring balance was measured by peeling from the foamed outer layer.

The method has the following defects: the void formation was visually identified after peeling off the outer layer. A distinction is made between void formation cases of "no" (no voids over 1 square meter of surface area), "slight" (at most 5% of surface area shows voids), "medium" (5-20% of surface area shows voids) and "severe" (more than 20% of surface area shows voids).

Table 3: formulation and Properties of rigid foams [ parts by weight ]

Examples 11 and 12：

Table 4: formulation of rigid PIR foams [ parts by weight ]

The rigid foams obtained according to examples 11 and 12 have the following properties when the density (ISO 845) is in the range 40-41 kg/m:

tensile strength: 0.14 n/mm (DIN 53292), tensile modulus (DIN 53292): 6.4N/mm

Compressive stress (DIN 53291): 0.15 n/mm, compression modulus (DIN 53291): 4.3N/mm

Shear strength (DIN 12090): 0.19 n/mm, shear modulus (DIN 12090): 3.8N/mm

The combustion properties of the rigid foams from examples 11 and 12 according to the invention were also tested in the single combustion test (SBI) according to EN 13823. For this purpose, commercial metal composite components were produced using metal composite components comprising the rigid foams of examples 11 or 12 according to the invention (see examples 17 and 18), and commercial metal composite components were produced using comparative foams (comparative examples 13 to 16), and tested. The results shown in table 5 below were obtained:

table 5: composition and properties of metal composite components

^*: repeat testing

For the FIGRA value (flame growth rate), values below 250W/s are rated as class C, and values below 120W/s are rated as class B. For THR₆₀₀Values (total exotherm after 600 seconds), values below 15MJ were rated as class C, and values below 7.5MJ were rated as class B. Is lower than180m²/s²SMOGRA values (smoke growth rate) of (D) were rated S2, below 30m²/s²Is rated as class S1. Below 200m²TSP of (1)₆₀₀The value (total smoke generation after 600 seconds) was rated as S2, below 50m²TSP of (1)₆₀₀The values are rated at S1.

So far, in the tested systems, the metal composite elements produced with the foam according to the invention (examples 17 and 18) had the lowest TSP₆₀₀The value is obtained. In the case of the metal composite member of example 18, TSP obtained₆₀₀The value was only 53 and when the test was repeated was only 47, the value was rated as S1. Low THR should also be of concern₆₀₀Values and SOMGRA values. The rigid foams according to the invention therefore exhibit a very advantageous overall burning behavior.

Claims (15)

1. A process for preparing a polyester polyol comprising the steps of:

a) at least one carboxylic anhydride (A) and diethylene glycol (B) are mixed together and reacted,

wherein the molar ratio of component (B) to (A) is in the range from 1.5: 1.0 to 0.7: 1.0, the ratio of components (A) and (B) relative to the weight of all components of the mixture is in the range from 66 to 90% by weight,

b) adding diethylene glycol (B) to the polyester polyol of step a),

wherein the molar mass of the polyester polyol of step a) is greater than the molar mass of the polyester polyol of step b),

characterized in that, in step a), at least one other C than diethylene glycol is added₂-C₄A diol (C) and at least one aliphatic C₅-C₁₂Dicarboxylic acid (D), or at least one C₅-C₁₀A diol (E) and at least one C₄A dicarboxylic acid (F).

2. The process according to claim 1, wherein the carboxylic anhydride (A) is selected from the group consisting of: phthalic anhydride, trimellitic anhydride and pyromellitic anhydride, the carboxylic anhydride preferably being phthalic anhydride.

3. The method of claim 1 or 2, wherein C is₂-C₄The diol (C) is selected from the group consisting of: ethylene glycol, 1, 3-propanediol, 2-methyl-1, 3-propanediol, 1, 2-propanediol, said C₂-C₄The diol (C) is preferably ethylene glycol.

4. The process as claimed in one or more of claims 1 to 3, characterized in that aliphatic C is used₅-C₁₂The dicarboxylic acid (D) is selected from the group consisting of: glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid and dodecanedioic acid, said C₅-C₁₂The dicarboxylic acid (D) is preferably adipic acid or sebacic acid.

5. The method according to one or more of claims 1 to 4, wherein C is₅-C₁₀The diol (E) is selected from the group consisting of: 1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 1, 6-hexanediol, and 1, 8-octanediol.

6. The method according to one or more of claims 1 to 5, wherein C is₄The dicarboxylic acid (F) is selected from the group consisting of: succinic acid, fumaric acid and maleic acid.

7. The process as claimed in one or more of claims 1 to 6, characterized in that the molar ratio of components (B) to (A) is in the range from 1.2: 1.0 to 0.75: 1.0.

8. The process according to one or more of claims 1 to 7, characterized in that the polyester polyols obtained in step a) have an OH number (theoretical OH number) based on the amount used in the range from 80 to 260 g KOH/kg.

9. The process as claimed in one or more of claims 1 to 8, characterized in that the polyester polyols obtained in step b) have OH numbers in the range from 150 to 320 g KOH/kg.

10. The process as claimed in one or more of claims 1 to 9, characterized in that the proportion of components (a) and (B) relative to the weight of all components is in the range from 66 to 90% by weight.

11. A polyester polyol obtainable by the process according to one or more of claims 1 to 10.

12. A process for the preparation of Polyurethane (PUR) or Polyisocyanurate (PIR) foams comprising the steps of:

reacting the following components:

a) polyester polyol obtainable by the process according to one or more of claims 1 to 10,

b) a component comprising a polyisocyanate, wherein the polyisocyanate is,

c) a blowing agent,

d) one or more catalysts selected from the group consisting of,

e) optionally flame retardants and/or other auxiliary substances and additives.

13. A PUR or PIR foam obtained by the process of claim 13.

14. Use of a Polyurethane (PUR) or Polyisocyanurate (PIR) foam according to claim 13 in the manufacture of metal composite elements.

15. A metal composite element comprising a metal layer and a layer comprising a PUR or PIR foam material according to claim 13.