EP4347681A1

EP4347681A1 - Rigid pur/pir foams, method of synthesis of a polyol for producing rigid pur/pir foams, and method for producing rigid pur/pir foams

Info

Publication number: EP4347681A1
Application number: EP22731530.6A
Authority: EP
Inventors: Thomas Bommer; Anton Demharter; Benjamin Felker; Michael Rhein; Michael Meier
Original assignee: Puren GmbH
Current assignee: Puren GmbH
Priority date: 2021-05-31
Filing date: 2022-05-25
Publication date: 2024-04-10
Also published as: KR20240015651A; DE102021114040A1; CA3220879A1; WO2022253685A1

Abstract

The invention relates to a rigid PUR/PIR foam produced from at least one polyol that is synthesized from at least one polyvalent alcohol and at least one aromatic dicarboxylic acid. According to the invention, at least part of the polyol is produced from renewable raw materials.

Description

PUR/PIR rigid foam, process for the synthesis of a polyol for the production of PUR/PIR rigid foams and process for the production of PUR/PIR rigid foams

PRIOR ART The invention relates to a PUR/PIR rigid foam according to the preamble of claim 1, a process for the synthesis of a polyol for the production of PUR/PIR rigid foams according to claim 12 and a process for the production of PUR/PIR rigid foams according to claim 25 .

Polyurethane (PUR) rigid foams and polyisocyanurate (PIR) rigid foams are known from the prior art and, due to their very low thermal conductivity, are used in a wide variety of thermal insulation applications, particularly in cold chains or in the construction industry and in industrial applications as insulating materials. Two main components are required for the production of PUR/PIR rigid foams, namely an isocyanate component and a polyol component, with the desired ones

Properties of the PUR/PIR rigid foams can be adjusted, among other things, by a suitable choice of the polyol component and the corresponding mixing ratios of the main components. To produce particularly stable PUR/PIR rigid foams, which can be used, for example, as building materials in the form of insulation boards, preference is given to using aromatic polyester polyols as the polyol component, which are characterized by the advantageous properties of the PUR/PIR rigid foams produced therefrom with regard to their fire behavior as well as their thermal conductivity. As a starting material for polyester polyols for the production of previously known In the case of PUR/rigid foams, petroleum-based aromatic dicarboxylic acids, for example phthalic acid or terephthalic acid, are used, which are synthesized with a polyhydric alcohol to form a polyester polyol. As a result of increased environmental awareness and due to limited resources for raw materials based on petroleum, there is also an increasing requirement for the production of PUR/PIR rigid foams to replace the petroleum-based aromatic carboxylic acids with suitable, more sustainable alternatives. While aliphatic chemical compounds can be produced from renewable raw materials relatively easily, for example from vegetable oils, aromatic chemical compounds have so far hardly been accessible from sustainable sources. So far, no bio-based alternatives are known from the prior art for the petroleum-based aromatic dicarboxylic acids, which would also enable the production of PUR/PIR rigid foams with technical properties comparable to conventional PUR/PIR rigid foams. A bio-based production of PUR/PIR rigid foams using methods known from the prior art was therefore not possible until now.

The object of the invention is in particular to provide a generic PU/PIR rigid foam with improved properties in terms of sustainability. The object is achieved according to the invention by the features of claims 1, 12 and 23, while advantageous configurations and developments of the invention can be found in the dependent claims.

Advantages of the Invention

The invention is based on a PUR/PIR rigid foam produced from at least one polyol which is synthesized from at least one polyhydric alcohol and at least one aromatic dicarboxylic acid. It is proposed that the polyol is at least partially made from renewable raw materials.

Such a configuration can advantageously provide a PUR/PIR rigid foam with improved properties in terms of sustainability. In particular, the use of petroleum-based starting materials can advantageously be reduced, preferably minimized or replaced entirely, as a result of which finite resources can be conserved and emissions of climate-damaging greenhouse gases can be reduced in the production of PUR/PIR rigid foams. In addition to its significantly improved properties in terms of sustainability, the PUR/PIR rigid foam according to the invention is also characterized in particular by its advantageous technical properties, in particular with regard to low thermal conductivity and low fire behavior, which are comparable to conventional PUR/PIR rigid foams or even surpass them.

The fact that the PUR/PIR rigid foam is “manufactured” from at least one polyol should be understood to mean that the PUR/PIR rigid foam has at least one polyol as at least one main component, the polyol in particular making up at least 25% by weight, preferably at least 30% by weight of the total mass of the PUR/PIR rigid foam. The PUR/PIR rigid foam is made of the at least one polyol, at least one isocyanate component, at least one blowing agent and in particular from other additives, in particular flame retardants and/or activators and/or emulsifiers and/or foam stabilizers and/or others, as useful to the person skilled in the art Appearing additives, and optionally using at least one catalyst, prepared by means of a polyaddition reaction. The polyol could be a polyether polyol. Preferably the polyol is a polyester polyol.

The polyhydric alcohol for the synthesis of the polyol is advantageously a dihydric alcohol, in particular ethylene glycol (MEG), preferably diethylene glycol (DEG). Alternatively, however, the use of trihydric, tetrahydric or polyhydric alcohols would also be conceivable in principle. The polyhydric alcohol could be synthetically produced. The polyhydric alcohol is preferably produced at least predominantly from renewable raw materials.

The aromatic dicarboxylic acid could be an aromatic dicarboxylic acid produced synthetically from petroleum-based raw materials, for example phthalic acid or terephthalic acid. However, the aromatic dicarboxylic acid is preferably produced at least predominantly from renewable raw materials.

"Renewable raw materials" are organic raw materials, in particular vegetable raw materials, which come from agricultural and/or forestry production and are cultivated by humans for further applications outside the food and feed industry or which are by-products and/or waste products from agriculture and/or the food and feed industry. Renewable raw materials within the meaning of the present application are exclusively organic raw materials that are not of fossil origin. In the present case, renewable raw materials are preferably domestic products from agricultural and/or forestry production and their by-products and/or residues, provided they are not subject to waste legislation, and algae.

The fact that the polyol is “at least partially” produced from renewable raw materials should be understood to mean that at least 50% by weight, in particular at least 60% by weight, advantageously at least 70% by weight, particularly advantageously at least 80% by weight. %, preferably at least 90% by weight and particularly preferably at least 95% by weight, of the polyol is made from renewable raw materials. It is also proposed that at least the aromatic dicarboxylic acid is produced predominantly from renewable raw materials. As a result, the durability of the PUR/PIR rigid foam can advantageously be further improved. The aromatic dicarboxylic acid is predominantly greater than 50% by weight, in particular greater than 60% by weight, advantageously greater than 70% by weight, particularly advantageously greater than 80% by weight, preferably greater than 90% by weight. -%, and particularly preferably in a proportion of 95% by weight up to and including 100% by weight, made from sustainable raw materials.

In addition, it is proposed that the aromatic dicarboxylic acid is 2,5-furandicarboxylic acid (FDCA), which is mainly produced from renewable raw materials. In this way, a sustainably produced PUR/PIR rigid foam can advantageously be provided with technical properties that are comparable or improved compared to conventional petroleum-based PUR/PIR rigid foams. The 2,5-furandicarboxylic acid can be produced at least predominantly from renewable raw materials, for example by dehydration of hexoses, in particular fructose, which can be obtained, for example, from sugar beet or sugar cane, and subsequent oxidation of the hydroxymethylfurfural (5-HMF) obtained therefrom. Furthermore, the production of 2,5-furandicarboxylic acid from waste from agriculture and/or the food industry, for example from old baked goods, from which hydroxymethylfurfural (5-HMF) is produced by means of hydrothermal treatment and subsequent extraction from an aqueous solution as a starting material for the 2, 5-furandicarboxylic acid can be obtained, conceivable. In addition, it is conceivable to produce 2,5-furandicarboxylic acid from inulin-accumulating plants, for example from inulin-containing chicory root beets, which accumulate as agricultural waste, with inulin first being extracted, then converted to hydroxymethylfurfural (5-HMF) by means of hydrothermal dehydration and then is oxidized biocatalytically or heterogeneously catalytically to 2,5-furandicarboxylic acid (FDCA). In a further advantageous embodiment it is proposed that at least the polyhydric alcohol is predominantly produced from renewable raw materials. As a result, the durability of the PUR/PIR rigid foam can advantageously be further improved. The majority of the polyhydric alcohol is greater than 50% by weight, in particular greater than 60% by weight, advantageously greater than 70% by weight, particularly advantageously greater than 80% by weight, preferably greater than 90% by weight. -%, and particularly preferably in a proportion of 95% by weight up to and including 100% by weight, made from renewable raw materials. Both the polyhydric alcohol and the aromatic dicarboxylic acid are preferably produced predominantly from renewable raw materials. In this way, a PUR/PIR rigid foam with a polyol produced predominantly from renewable raw materials and thus particularly advantageous properties with regard to sustainability can advantageously be provided.

Furthermore, it is suggested that the polyol has an OH number greater

250 mg KOH/g. This advantageously makes it possible to provide a PUR/PIR rigid foam with a high linkage density and thus good dimensional stability and high compressive strength, which is desired for many applications. The polyol advantageously has a higher OH number

250 mg KOH/g and less than 400 mg KOH/g, preferably less than 350 mg KOH/g, preferably less than 300 mg KOH/g and particularly preferably less than 275 mg KOH/g.

In addition, it is proposed that the polyol has a free glycol content of greater than 6% by weight, based on the total mass of the polyol. In this way, a PUR-PIR rigid foam with a wide range of applications can advantageously be provided. The polyol preferably has a free glycol content of less than 20% by weight, particularly preferably at most 15% by weight, based on the total mass of the polyol. It is also proposed that the polyol has an average molar mass of less than 1000 g/mol. The polyol advantageously has an average molar mass or molecular weight of between 400 g/mol and 900 g/mol, preferably between 600 g/mol and 850 g/mol. The polyol particularly preferably has an average molar mass of less than 700 g/mol. In this way, a PUR/PUR rigid foam with a low density (RG) can advantageously be provided. The mean molar mass of the polyol can be determined, for example, by means of nuclear magnetic resonance spectroscopy (H1-NMR). Correlated spectroscopy (COSY) and/or heteronuclear single quantum coherence (HSQC) and/or heteronuclear multiple bond correlation (HMBC) and/or size exclusion chromatography (SEC) and/or infrared spectroscopy can also be used (IR) can be performed to determine the structure and/or other characteristics of the polyol.

In a further advantageous embodiment it is proposed that the polyol is at least partially synthesized from at least one further dicarboxylic acid. As a result, a dynamic viscosity of the polyol can advantageously be reduced and thus improved processability can be achieved. A PUR/PIR rigid foam with improved properties in terms of manufacturability can therefore advantageously be provided. The other dicarboxylic acid could be an aromatic dicarboxylic acid, for example phthalic acid or terephthalic acid.

In a particularly advantageous embodiment, however, it is proposed that the further dicarboxylic acid is an aliphatic dicarboxylic acid which is predominantly produced from renewable raw materials. A configuration of this type can advantageously further improve the sustainability of the PUR/PIR rigid foam, while at the same time advantageously a dynamic viscosity of the polyol can be lowered and thus production of the PUR/PIR rigid foam can be improved. It is preferably the another dicarboxylic acid is an aliphatic C4 to C10 dicarboxylic acid, which is mainly produced from renewable raw materials. The other dicarboxylic acid could be, without being restricted to this, for example succinic acid and/or adipic acid, which are predominantly produced from renewable raw materials. The other dicarboxylic acid is predominantly greater than 50% by weight, in particular greater than 60% by weight, advantageously greater than 70% by weight, particularly advantageously greater than 80% by weight, preferably greater than 90% by weight. -%, and particularly preferably in a proportion of 95% by weight up to and including 100% by weight, made from renewable raw materials.

In addition, it is suggested that the polyol has a dynamic viscosity of between 3,000 mPas and 12,000 mPas. As a result, improved processability of the polyol and thus a PUR/PIR rigid foam with improved properties in terms of manufacturability can advantageously be provided. In particular, the polyol has a dynamic viscosity between 4000 mPas and 8000 mPas, advantageously between 4000 mPas and 7000 mPas, particularly advantageously between 4000 mPas and 6000 mPas, preferably between 4000 mPas and 5500 mPas and particularly preferably between 4000 mPas and 5000 mPas. The specified dynamic viscosities refer to measurements according to the DIN EN ISO 3219 standard.

Furthermore, it is suggested that the PUR/PIR rigid foam has a thermal conductivity of between 0.018 W/(mK) and 0.021 W/(mK). In this way, a PUR/PIR rigid foam with improved thermal insulation properties can advantageously be provided. The PUR/PIR rigid foam preferably has a thermal conductivity of between 0.019 W/(mK) and 0.020 W/(mK). The thermal conductivity of the PUR/PIR rigid foam in the range between 0.018 W/(mK) and 0.021 W/(mK) is a measured value measured immediately after production. Conventional PUR/PIR rigid foams with particularly good thermal insulation, which are based on petroleum-based polyols, a polyisocyanate and the blowing agent pentane typically have thermal conductivities measured immediately after their manufacture in the range between 0.020 W/(mK) and 0.021 W/(mK). It is known that the plastic polyethylene furanoate (PEF) in the use of bio-based plastic containers has improved diffusion tightness compared to the plastic polyethylene terephthalate (PET), with an 02 barrier of PEF compared to PET being up to six times greater, a C02 barrier of PEF is up to three times greater than PET and an H2O barrier of PEF is up to twice greater than PET. Since PEF consists of the starting materials 2,5-furandicarboxylic acid (FDCA) and ethylene glycol (MEG) and the polyol for producing the PUR/PIR rigid foam according to the invention is produced in particularly preferred embodiments from a polyol of furandicarboxylic acid (FDCA) and diethylene glycol (DEG). , whose proportion of the PUR/PIR rigid foam accounts for at least 25% by weight, preferably at least 30% by weight, of the total mass, it can be assumed that the very good barrier properties of the PEF against O2, CÜ2und H2O correspond to the proportion of the polyol can also be transferred proportionally to the PUR/PIR rigid foam according to the invention. It is therefore assumed that this reduces the thermal conductivity of the PUR/PIR rigid foam according to the invention by at least 5% compared to conventional PUR/PIR rigid foams blown by means of pentane, so that thermal conductivities of between 0.018 W/(mK) and 0.021 W/( mK), preferably between 0.019 W/(mK) and 0.020 W/(mK). The specified thermal conductivity of the PUR/PIR rigid foam refers to measurements according to DIN EN 12667.

The present invention is also based on a method for synthesizing a polyol for producing PUR/PIR rigid foams, in particular according to one of the configurations described above, from at least one polyhydric alcohol and at least one aromatic dicarboxylic acid. It is proposed that renewable raw materials are at least partially used as starting materials. Such a process can advantageously produce a sustainable polyol for the production of PUR/PIR rigid foams to be provided. The fact that renewable raw materials are used "at least partially" as starting materials should be understood to mean that at least 25% by weight, preferably at least 30% by weight, of the total mass of starting materials used in the process are made from renewable raw materials . The method includes at least one method step. The method preferably comprises at least two method steps. The process is preferably a one-step synthesis. The polyhydric alcohol is preferably initially introduced and preheated in one process step and in a further process step the aromatic dicarboxylic acid and preferably at least one catalyst are added to the polyhydric alcohol and the reaction mixture is then stirred. Condensate occurring in the further process step is preferably distilled off continuously, in particular in order to shift a reaction equilibrium to the product side and to prevent a reverse reaction in the form of ester cleavage of the polyol. In order to achieve complete conversion of the starting materials, the reaction mixture is advantageously stirred for at least 5 hours, preferably for at least 7.5 hours, particularly preferably for at least 10 hours. In principle, shorter stirring times would also be conceivable, with a lower conversion of the starting materials to polyol having to be expected. The reaction mixture is preferably stirred with at least one stirring element at speeds of from 150 rpm to 450 rpm. However, depending on the type and size of the reactor used and the stirring element used, other speeds could also prove to be expedient.

Furthermore, it is proposed that at least one aromatic dicarboxylic acid, which is produced predominantly from renewable raw materials, is used. A particularly sustainable method can advantageously be enabled by flow.

In a particularly advantageous embodiment, it is proposed that 2,5-furandicarboxylic acid (FDCA), which mainly consists of renewable Raw materials is produced, as aromatic dicarboxylic acid is used. In this way, a particularly sustainable process can advantageously be made possible, with a polyol having particularly advantageous properties for the production of PUR/PIR rigid foams being able to be synthesized at the same time.

2,5-Furandicarboxylic acid (FDCA), which is produced predominantly from renewable raw materials, is particularly preferably used as aromatic dicarboxylic acid and diethylene glycol (DEG), which is advantageously produced predominantly from renewable raw materials, to produce aromatic poly(diethylene glycol furanoate) (PDEF) obtainable as a polyol.

In a particularly preferred embodiment, it is proposed that diethylene glycol (DEG) is used as the polyhydric alcohol and the process is carried out according to the following generalized reaction scheme:

, where n can assume positive values between 1.0 and 10.0 in particular and x can assume positive values between 0.0 and 5.0 in particular. As a result, the process for synthesizing the polyol can advantageously be matched particularly well to the production of PUR/PIR rigid foams. In the generalized reaction scheme mentioned above, n can in particular have positive values between 1.0 and 10.0, advantageously between 1.0 and 7.0, particularly advantageously between 1.0 and 5.0, preferably between 1.0 and 4.0 , preferably between 2.0 and 4.0. n particularly preferably has a value between 2.0 and 3.0. In principle, positive values greater than 10.0 are also conceivable for n. In the present case, the specified value ranges of n relate to macromolecules of the polyol and therefore represent statistical mean values. In the reaction scheme mentioned above, x can in particular have positive values between 0 and 5, advantageously between 0 and 4, particularly advantageously between 0 and 3, preferably between 0 and 2 and preferably between 0.5 and 1.5 accept. x particularly preferably has a value of 1. In principle, positive values greater than 5.0 are also conceivable for x.

In addition, it is proposed that at least one polyhydric alcohol, which is predominantly produced from renewable raw materials, is used. As a result, the sustainability of the method can advantageously be further improved.

It would be conceivable for the process to be carried out without a catalyst. In order to achieve advantageous reaction kinetics, however, it is proposed that at least one catalyst be used. Metal oxides and/or organometallic compounds could be used as the catalyst. For example, it would be conceivable to use dibutyltin(IV) oxide as a catalyst. The catalyst is based on the starting concentration of dicarboxylic acid (s) in an equivalent concentration of at least 0.01, in particular at least 0.02, advantageously at least 0.03, preferably at least 0.04 and particularly preferably at least 0.05, added based on the initial concentration of dicarboxylic acid.

In a particularly advantageous embodiment, it is proposed that at least one catalyst containing titanium be used. Titanium-containing catalysts are non-toxic and therefore advantageously enable the process to be carried out simply and safely. In addition, titanium-containing catalysts are characterized in particular by their high catalytic activity, so that a particularly efficient process can advantageously be achieved in this way. Several different titanium-containing catalysts could be used, or at least one titanium-containing catalyst and at least one non-titanium-containing catalyst could be used. Preferentially exactly one titanium-containing catalyst is used. It is known that at least two reaction steps take place in a synthesis of polyols from polyhydric alcohols and dicarboxylic acids, with a reaction to a corresponding dicarboxylic acid diester taking place in a first reaction step and a reaction step taking place in a second reaction step Polycondensation to form a polyol takes place, with polyhydric alcohol and water being released as a condensate. Both reaction steps require catalysts or are at least accelerated by such, with titanium-containing catalysts being advantageously usable for the catalysis of both reaction steps. A particularly efficient process for synthesizing a polyol for producing PUR/PIR rigid foams can thus be provided if precisely one catalyst containing titanium is used. The titanium-containing catalyst could be, for example, sodium titanate. Preferably, the titanium-containing catalyst is tetraisopropyl orthotitanate and most preferably titanium tetrabutanolate.

The polyhydric alcohol could be used, for example, in an equivalent concentration of 2.5 or 3.0 based on an initial concentration of the dicarboxylic acid(s). In a particularly advantageous embodiment, however, it is proposed that the polyhydric alcohol be used in an equivalent concentration of between 1.75 and 2.00, based on an initial concentration of the aromatic dicarboxylic acid(s). Such a configuration can advantageously achieve complete conversion of the starting materials into polyol and, on the other hand, the lowest possible degree of polymerization and, associated therewith, the lowest possible dynamic viscosity of the polyol. A particularly efficient process for the synthesis of a polyol for the production of PUR/PIR rigid foams can therefore be provided. In particular, a high product yield can advantageously be achieved with the lowest possible use of polyhydric alcohol, as a result of which a high cost-efficiency of the method is advantageously achieved and sustainability is improved even further. In addition, the lowest possible content of free glycol can advantageously be achieved, since too high a proportion of free glycol, in particular a proportion greater than 20% by weight based on the total mass of the polyol, affects the technical properties of a PUR/PIR produced from the polyol - Hard foam can have a negative effect. In addition, it is proposed that a reaction mixture of the starting materials is stirred at a temperature between 60.degree. C. and 240.degree. In particular, to achieve a reaction rate that is sufficient for economic purposes, the reaction mixture is advantageously stirred at a temperature of at least 75.degree. C., particularly advantageously at least 100.degree. C., preferably at least 125.degree. C. and particularly preferably at least 150.degree. On the other hand, the selected temperature has a great influence on the rate of polymerization, with the degree of polymerization of the polyol and, consequently, also the dynamic viscosity of the polyol increasing with increasing temperature. Furthermore, if the temperatures are too high, undesirable side reactions and/or partial evaporation of the starting materials can occur. The reaction mixture is therefore stirred in particular at a temperature of not more than 230°C, advantageously not more than 220°C, particularly advantageously not more than 210°C, preferably not more than 200°C and particularly preferably not more than 190°C. Depending on the batch size of the reaction mixture, it may be necessary, particularly for smaller batch sizes on a laboratory scale, for the reaction mixture to be heated using at least one external heat source in order to reach a temperature between 60°C and 240°C. On the other hand, since the reaction is exothermic, it may also be necessary, particularly for large batch sizes on an industrial scale, for the reaction mixture to be cooled in order not to exceed a temperature of 240°C. In tests by the applicant, a reaction temperature of 160° C., at which the reaction mixture was stirred, has proven to be particularly advantageous in order to achieve a sufficiently rapid reaction on the one hand and the lowest possible degree of polymerization and thus the lowest possible dynamic viscosity of the polyol on the other. Since the temperature of the reaction mixture, in addition to the selected starting materials and the selected catalyst and the batch size, depends on a large number of other parameters, such as the stirring speed, the type of stirrer used, the thermal conductivity and heat transfer of the components of the reactor used and the like , could for some reactors for carrying out the process, temperatures which deviate from the abovementioned ranges have in principle also proved to be advantageous. In particular, depending on the type of catalyst used, temperatures of the reaction mixture of greater than 240° C. are also conceivable in principle.

Furthermore, it is proposed that at least one further dicarboxylic acid is additionally used. In this way, a dynamic viscosity of the synthesized polyol can advantageously be lowered. The other dicarboxylic acid can be an aromatic dicarboxylic acid, for example phthalic acid or terephthalic acid. The further dicarboxylic acid is preferably an aliphatic dicarboxylic acid, particularly preferably an aliphatic dicarboxylic acid produced at least predominantly from renewable raw materials, for example succinic acid and/or adipic acid. In this way, a dynamic viscosity of the synthesized polyol can advantageously be reduced using renewable raw materials. A particularly sustainable method can thus be made possible.

In a further advantageous embodiment, it is proposed that at least one surfactant, which is predominantly produced from renewable raw materials, is additionally used. As a result, a polyol with a higher degree of polymerization can advantageously be synthesized using renewable raw materials, without the dynamic viscosity of the polyol thereby increasing at the same time. The surfactant is predominantly greater than 50% by weight, in particular greater than 60% by weight, advantageously greater than 70% by weight, particularly advantageously greater than 80% by weight, preferably greater than 90% by weight. %, and particularly preferably in a proportion of 95% by weight up to and including 100% by weight, made from renewable raw materials. The surfactant could be, for example, a polyethylene glycol dodecyl ether, which is available under the trade name Brij™ L4 and is mainly made from renewable raw materials. The invention further relates to a polyol synthesized by a method according to any of the embodiments described above. A polyol synthesized using the process according to the invention is characterized on the one hand by its advantageous properties with regard to sustainability and on the other hand by its properties for the production of PUR/PIR rigid foams which are comparable or even better than those of conventional polyols synthesized from petroleum-based starting materials. In particular, the polyol synthesized using the process according to the invention has comparable or improved properties with regard to foamability compared to PUR/PIR rigid foams. To process the polyol according to the invention into PUR/PIR rigid foams, no changes worth mentioning and/or exceeding the usual extent in the formulation and the process technology of the foaming systems are therefore required, so that advantageously standard-compliant PUR/PIR rigid foams with the usual or improved quality can be provided. At the same time, sustainability is significantly improved compared to conventional PUR/PIR rigid foams. Due to the synthesis of the polyol from aromatic dicarboxylic acids, which are mainly produced from renewable raw materials, the polyol according to the invention would be easy for a person skilled in the art to produce from conventional polyols previously known from the prior art using suitable measurement methods, for example by means of nuclear magnetic resonance spectroscopy (H1-NMR). distinguishable from PUR/PIR rigid foams.

In addition, it is proposed that the polyol is poly(diethylene glycol furanoate) (PDEF), which has the following generalized structure:

, where n can in particular assume positive values between 1.0 and 10.0. In this way, a polyol can advantageously be provided which is produced predominantly, preferably entirely, from renewable raw materials and which is particularly suitable for the production of PUR/PIR rigid foams, since it has comparable or even improved properties to polyols based on fossil raw materials that have been commercially available to date having. In the above generalized structural formula of the polyol, n can in particular have positive values between 1.0 and 10.0, advantageously between 1.0 and 7.0, particularly advantageously between 1.0 and 5.0, preferably between 1.0 and 4 .0, preferably between 2.0 and 4.0. n particularly preferably has a value between 2.0 and 3.0. In principle, positive values greater than 10.0 are also conceivable for n. In the present case, the value ranges given for n refer to macromolecules of the polyol and therefore represent statistical mean values.,

The invention also relates to a method for producing PUR/PIR rigid foams, in particular according to one of the configurations described above, in which at least one polyisocyanate, at least one polyol which is at least partially synthesized from renewable raw materials, in particular according to one of the methods described above for synthesizing the polyol, and at least one blowing agent can be converted into a PUR/PIR rigid foam. A particularly sustainable production of PUR/PIR rigid foams can advantageously be achieved by such a method. The polyisocyanate can be, for example, but not limited to, polymeric diphenylmethane diisocyanate (PMDI) and/or methylene diphenyl isocyanate (MDI) and/or hexamethylene diisocyanate (HDI) and/or tolylene diisocyanate (TDI) and/or naphthylene diisocyanate (NDI) and/or isophorone diisocyanate (IPDI) and/or 4,4'-

diisocyanatodicyclohexylmethane (H12MDI). Preferably, the polyisocyanate is polymeric diphenylmethane diisocyanate (PMDI). The blowing agent is preferably pentane. Alternatively or additionally, CO2, which is formed when water is added by reacting with the isocyanate component, and/or partially fluorinated hydrocarbons, for example HFC-365mfc and HFC-245fa, would also be conceivable as blowing agents. In addition, other additives, in particular flame retardants and/or activators, and/or emulsifiers and/or foam stabilizers and/or other additives that appear sensible to those skilled in the art, can be used in the process. In addition, the use of catalysts in the process is conceivable. In the process, polyurethanes are formed by a polyaddition reaction of the polyisocyanate with the polyol. Linear polyurethanes can be crosslinked by using excess polyisocyanate. Addition of an isocyanate group to a urethane group forms an allophanate group. It is also possible to form an isocyanurate group by trimerizing three isocyanate groups. If polyfunctional polyisocyanates are used, highly branched polyisocyanurates (PIR) are formed so that PIR fl art foams can be obtained. Preferably, PUR/PIR flat foams with a PIR index of 200 to 400, preferably with a PIR index of 250 to 350 and particularly preferably with a PIR index of 290 to 310 are synthesized in the process.

Further advantages and further embodiments of the present invention result from the following description of the exemplary embodiments and from the claims. The person skilled in the art will expediently also consider the features mentioned here individually and combine them to form further meaningful combinations. It goes without saying that the features of the invention mentioned above and explained below can be used not only in the combination specified in each case, but also in other combinations, without the ones described above and below leave the scope of the invention. In particular, the combination of at least one preferred feature with at least one particularly preferred feature, or the combination of at least one uncharacterized feature with at least one preferred and/or particularly preferred feature is also implicitly included, even if such combinations are not expressly mentioned. Furthermore, the following exemplary embodiments relate to embodiments of the invention on a laboratory scale, so that individual parameters and/or characteristics specified below can change slightly when the invention is scaled up to an industrial scale, without thereby departing from the scope of the invention described above and below becomes. Description of the exemplary embodiments

The following are exemplary embodiments of the present invention, which do not limit the present invention.

A process for the synthesis of a polyol for the production of PUR/PIR flat foams and a process for the production of PUR/PIR flat foams are described in general terms below before the individual exemplary embodiments are discussed in detail.

In the process for the synthesis of the polyol, for the production of PUR/PIR flart foams, from at least one polyhydric alcohol and at least one aromatic dicarboxylic acid, renewable raw materials are used at least in part as starting materials. In the present case, at least one aromatic dicarboxylic acid, namely 2,5-furandicarboxylic acid (FDCA), which is predominantly produced from renewable raw materials, is used. In addition, at least one polyhydric alcohol, which is predominantly produced from renewable raw materials, is used. At least one catalyst is also used. In all of the following exemplary embodiments, the method comprises at least two method steps, with a single-stage method or a method having more than two method steps also being conceivable in principle. In a first step of the process At least one polyhydric alcohol, in the present case exactly one polyhydric alcohol, is introduced into the process and preheated. In the first process step, the polyhydric alcohol is initially introduced and preheated in all exemplary embodiments in an equivalent concentration of between 1.75 and 2.00, based on the starting concentration of dicarboxylic acid(s). In a second process step, a 2,5-furandicarboxylic acid (FDCA) produced predominantly from renewable raw materials is added as an aromatic dicarboxylic acid in all exemplary embodiments. In all of the exemplary embodiments, a reaction mixture of the starting materials is stirred at a temperature of between 60° C. and 240° C. in the second process step. The reaction mixture is stirred at speeds between 150 RPM and 450 RPM.

In some exemplary embodiments of the method, a titanium-containing catalyst is used as the catalyst.

In some exemplary embodiments, at least one further dicarboxylic acid is additionally used, in particular to reduce the dynamic viscosity of the polyol to be synthesized.

In one exemplary embodiment, at least one surfactant is additionally used, which is predominantly produced from renewable raw materials.

The process is carried out according to the following generalized reaction scheme: n

, where n, in particular, can assume positive values between 1.0 and 10.0 and x, in particular, can assume positive values between 0.0 and 5.0. In some exemplary embodiments, other starting materials and/or catalysts are used in addition to 2,5-furandicarboxylic acid and diethylene glycol. The resulting polyol is a poly(diethylene glycol furanoate) (PDEF) which has the following generalized structure: where n can, in particular, assume positive values between 1.0 and 10.0. n preferably has a value between 2 and 3.

The polyol obtained in this way, at least partially synthesized from renewable raw materials, is then further processed in a process for the production of PUR/PIR rigid foams, in which at least one polyisocyanate, the polyol synthesized at least partially from renewable raw materials and at least one blowing agent are combined to form a PUR/PIR Rigid foam are implemented.

In the process for manufacturing PUR/PIR rigid foams, methylene diphenyl isocyanate (MDI) is used as the polyisocyanate and pentane as the blowing agent. In the process for producing PUR/PIR rigid foams on a laboratory scale, the polyol, at least one flame retardant, at least one catalyst, at least one foam stabilizer and water are placed in a glass beaker and premixed. Then the pentane is added and mixed again. Then the polyisocyanate is added and stirred for at least 20 seconds with a laboratory mixer at 2000 rpm. The reaction mixture is then poured into a lined foam wood mold measuring 20×20×20 cm ³ and covered with a lid. The PUR/PIR rigid foam is synthesized with a PIR index of 200 to 400, preferably 250 to 350, particularly preferably about 300.

materials For the experiments described in this application, the following chemicals were used as received: 2,5-furandicarboxylic acid (FDCA, 98%, BLDpharm), adipic acid (AA, 99%, Acros Organics), dibutyltin (IV) oxide (98%, Sigma Aldrich), Brji® L4 (Sigma Aldrich), CATALYST LB (Huntsman), DABCO® TMR13 (Evonik), Desmodur® 44V70L (Covestro), Desmophen® V657 (Covestro), diethylene glycol (DEG, 99%, chemPUR), dimethyl sulfoxide -d6 (DMSO-d6, 99.9 atom% D, Sigma Aldrich), pentane (60% cyclohexane, 40% isopentane, Julius Floesch), phthalic acid (>99.5%, Sigma Aldrich), POLYCAT® 36 (Evonik) , STRUKSILON KOCT 15 (Schill+Seilacher), succinic acid (SA, 99%, Acros Organics), TEGOSTAB® B84510 (Evonik), tetraisopropyl orthotitanate (97%,

Sigma Aldrich), triethyl phosphate (TEP, PROCHEMA), tris(chloroisopropyl) phosphate (TCPP, PROCHEMA).

preliminary tests

Since a poly(diethylene glycol furanoate) (PDEF) is to be obtained as a processable oil for the production of PUR/PIR rigid foams, preliminary tests were initially carried out in order to optimize the reaction conditions. It has been shown that the use of ethylene glycol (EG) as a polyhydric alcohol led to solid polyols which could not be processed for the production of PUR/PIR rigid foams, so that in the exemplary embodiments described below, diethylene glycol (DEG) was used instead of ethylene glycol (EG ) is used as a polyhydric alcohol. Furthermore, the exemplary embodiments described below are based on the following considerations: Typical OH values of commercially available aromatic polyester polyols for the production of rigid PUR/PIR foams are 240 mg KOH/g, including the amount of remaining unreacted glycol. Therefore, a desired PDEF polyol molecular weight of approximately 468 g/mol was calculated using Equation 1 below: where Mn is the molecular weight of the polyol, z is the functionality of the polyol and OH is the OH number of the polyol. However, this molecular weight underestimates the molecular weight of the polyester polyol because the excess glycol is not accounted for in this calculation. In addition, the degree of polymerization Xn for the investigated poly(diethylene glycol furanoate) was calculated using the following equation 2 to be 1.6: where Mend group is the molecular weight of the end group and Mrepeating unit is the molecular weight of the repeating unit. According to the Carothers equation for AA/BB systems, which is given below as Equation 3, the stoichiometric ratio of diethylene glycol and 2.5 furandicarboxylic acid was calculated with r = 0.24 for p = 1: where: and where r represents a ratio between a number of molecules NA and a number of molecules NB, and p indicates a degree of conversion. However, the assumption made in the last calculation was not suitable for all practical purposes, since complete conversion (p = 1) could not be guaranteed and even small differences in the conversion have a significant influence on the observed molecular weight. Besides, it has to Condensate are constantly removed to achieve high sales, with diethylene glycol was partially evaporated with the water formed. Therefore, the initial molar ratio will change during the reaction, affecting the molecular weight. Thus, the values calculated above provide a valuable starting point for the polymerization studied, but the

Reaction conditions must be optimized by varying the amount of diethylene glycol to obtain a small excess of glycol, the desired molecular weight and a still workable viscosity.

The reaction control was carried out by means of ¹ H-NMR, as shown in FIG. The conversion of 2,5-furandicarboxylic acid will be determined by the ratio of the signals with a chemical shift of 7.27 ppm and 7.30-7.46 ppm, as illustrated in Equation 4 below:

In addition, the degree of polymerization was calculated from the two signals from the assigned CFl2 group of the diethylene glycol moiety in the polymer backbone and the end group at 3.80 ppm and 3.70 ppm, respectively, using Equation 5 below:

The calculation of X _n via ¹ FI-NMR with Xn = 1 for n = 0 was normalized to the aromatic protons of the furan repeat unit. The excess of unreacted diethylene glycol (DEG) was determined by the isolated signal from the 0(CH2CH20H)2 proton with a chemical shift of 3.40 ppm from Equation 6 below:

The calculation of the DEG excess via ¹ H-NMR in wt.% was normalized to the aromatic protons of the furan repeat unit.

Figure 1 shows an exemplary ¹ FI NMR of PDEF used to determine the conversion of FDCA, excess DEG and Xn measured in DMSO-d6.

First, various catalysts for the polymerization were investigated. Tin catalysts are widely used in industry due to their high catalytic activity in esterification and transesterification reactions.

Dibutyltin(IV) oxide (SnOBu2) also showed good results for the system investigated here, with almost complete conversion of FDCA (>98%) being achieved after 4 hours. Tetraisopropyl orthotitanate (Ti(0'Pr)4) is nowadays a typical catalyst for the industrial synthesis of many different esterification and transesterification products. This catalyst also showed good catalytic activity, with almost complete conversion of FDCA (>99 %) being achieved after 24 h. In a reference reaction without a catalyst, only 70% of FDCA was converted after 24 hours, which clearly shows that the use of a catalyst is advantageous. From a sustainability standpoint, tin catalysts are highly toxic and dangerous. Since they remain in the final polyol, this catalyst was of no further interest. Since tetraisopropyl orthotitanate represents a good compromise between catalytic activity and sustainability, this catalyst was used for further investigations.

As described above, the molar ratio of DEG and FDCA had to be adjusted experimentally to find the best fit between full conversion, the desired X _n , and a small excess of DEG. For this purpose, an aromatic polyester polyol available in Flandel was developed Phthalic acid base (PDEP, cf. Figure 2, polyol 4) selected as reference polyol containing 0.50 equivalent of unreacted DEG. The test parameters used in the preliminary tests carried out to optimize the reaction conditions for different equivalent concentrations of diethylene glycol (DEG) are shown in Table 1 below:

Table 1: Optimization of the reaction conditions at different equivalent concentrations of DEG For the experiments designated as entries 1 to 4 in Table 1, 1.00 equivalents of 2,5-furandicarboxylic acid (FDCA) and 5 mol % of tetraisopropyl orthotitanate were used in each case. The reactions were each carried out at 160°C.

During this series of experiments, the reaction was stopped as soon as the heterogeneous solution of FDCA and DEG turned into a homogeneous melt. At this point, high conversion of FDCA to the corresponding esters, which have melting points below 160°C, was observed. After 1 hour, 95% of FDCA had already reacted with 3.00 equivalents of DEG (cf. entry 1, Table 1), determined by ¹ FI NMR via the ratio of the signals with a chemical shift of 7.27 ppm and 7.30 -7.46ppm as shown in Figure 1. In addition, the degree of polymerization Xn of 1.5 was close to the desired calculated value, but under these conditions 1.75 equivalents of unreacted DEG remained in the polyol (cf. Entry 1, Table 1). Xn and the excess of DEG were calculated as described above from the signals with a chemical shift of 3.70 ppm, 3.80 ppm and 3.40 ppm of the corresponding proton NMR (see FIG. 1). When only 2.50 equivalents of DEG were used, the same conversions and Xn were observed, while the excess of DEG was reduced to 1.25 equivalents (cf. Entry 2, Table 1). Entry 3 in Table 1 shows that polyethylene glycol dodecyl ether, which is available under the trade name Brji® L4, can also be added as a surfactant to reduce the viscosity without having any negative effects on the reaction system. The slightly lower Xn value can be explained by the chemical structure of the surfactant, which carries an OFI and thus acts as a chain stopper in the polycondensation. The total amount of reactive OFI groups is also slightly higher compared to entry 2. Best results were obtained with 2.00 equivalents of DEG, as shown in entry 4 of Table 1, with the excess of DEG reduced to 1.00 equivalents. Since a homogeneous solution was observed after 35 minutes, only 85% of the dicarboxylic acid were implemented, so that the Amount of unreacted DEG can be further reduced for higher sales. With longer reaction times, the conversion of FDCA can be increased to up to 99%, which is associated with an increased X _n of 1.7, while the excess of DEG was reduced to 0.75 equivalents after 2.5 hours. The viscosity of the polyol can be further reduced by copolymerization of bio-based aliphatic dicarboxylic acids such as succinic acid (SA) or adipic acid (AA), while maintaining the fully bio-based character of the polyol. The reaction conditions of corresponding preliminary tests are shown in Table 2: Table 2: Copolymerization of various dicarboxylic acids with FDCA

Entries 1 and 2 in Table 2 showed almost complete conversion of 2,5-furandicarboxylic acid (FDCA) and succinic acid (SA) or adipic acid (AA) while the degree of polymerization was as desired. In the succinic acid approach, the DEG excess was slightly higher, which is due to incompletely converted FDCA. In general, longer reaction times were required compared to the results reported in Table 1, due to a scale-up to almost 5.00 g of dicarboxylic acid, where mixing with a magnetic stirrer was more difficult. Another approach was the copolymerization of phthalic acid (PA) to preserve the fully aromatic character of the dicarboxylic acid. In this case, the polyol is due to the Petroleum-based phthalic acid is no longer fully bio-based. Entry 3 in Table 2 showed complete conversion of FDCA and PA with a 0.55 equivalent excess of DEG. However, the degree of polymerization could not be determined because the signals in the proton NMR overlapped. As a fully biobased character is sought, the copolymerization of a petroleum-based aromatic carboxylic acid was not further investigated.

For the subsequent PU synthesis, a scale-up of selected reactions up to 100 g dicarboxylic acid was carried out as a next step, which was carried out using the optimized conditions for a flomopolymer from FDCA (polyol 1) and copolymers with 10 mol% of either succinic acid (polyol 2) or

Adipic acid (polyol 3) succeeded. The scale-up attempts are shown in Table 3:

Table 3: Scale-up reactions of polyol synthesis using 2,5-furandicarboxylic acid and 10 mol% succinic acid or adipic acid

Here, the polycondensation was stirred for 2 to 6 days to ensure complete conversion of the carboxylic acid groups, since otherwise the amine catalyst for PU foaming would be deactivated, as was also observed here. Laboratory scale mixing for these scale-up reactions was less efficient than smaller scale. However, even after these long reaction times, the Xn value remained in the range of the desired value, indicating good molecular weight control among those optimized Reaction conditions indicates. The traces of

Size exclusion chromatography (SEC) of polyols 1-3 shown in Figure 2 confirms this observation. A residence time in minutes is plotted on an abscissa 5 of the diagram in FIG. A normalized detector signal I is plotted on an ordinate of the diagram.

Furthermore, the amount of unreacted DEG was similar to that of commercial polyol 4. As already mentioned, the desired degree of polymerization was slightly underestimated since the measured OH values already accounted for the excess DEG remaining in the polyol. This can be clearly seen by comparing the SEC traces of the commercial polyol 4 and the fully bio-based polyols 1 to 3 (cf. FIG. 2). A comparison of the OH values determined by means of proton NMR without DEG and the measured values including the unreacted DEG is shown in Table 3. As expected, the measured values of 300-350 mg KOH/g were higher than those of the commercial polyol 4, but they were necessary for this system because higher Xn led to highly viscous and therefore unprocessable PDEF.

In addition, the OH values determined by means of ¹ H-NMR can be correlated with the measured values, which proves the suitability of this method.

In a next step, the completely bio-based polyols 1 to 3 were processed with methylene diphenyl diisocyanate (MDI) to form PIR rigid foams. All three polyols showed suitable reactivity as good and very fast foaming took place, also compared to the commercial polyol. The reaction between Polyol 1 and methylene diphenyl isocyanate (MDI) started 20 seconds after mixing the two components, while foaming was complete after 50 seconds. Polyols 2 and 3 showed similar reactivity. All of the foams cured very quickly.

Finally, important properties of the PIR rigid foams obtained were examined. These properties are summarized in Table 4:

Table 4: Thermal and mechanical properties of the PIR rigid foam for the various polyols 1-4.

All PIR foams were synthesized using the procedure described above with a PIR index of approximately 300. In this process, in some cases up to 15 mol % of a commercial trifunctional polyether polyol improved

Miscibility added. The resulting PIR foam from Polyol 1 showed a similar thermal conductivity at 23°C (A23°C) of 23.1 mW/m ^* K and a rise direction compressive strength (a _m ) of 296 kPa compared to commercial Polyol 4 (23 .4 mW/m ^* K, 283 kPa) and an identical density of 33.4 kg/m3 (see Table 4, entries 1 and 2). The thermal conductivity values given in Table 4 relate to measurements of PIR foams produced on a laboratory scale at 23°C. In the case of a scale-up of the process for the production of PIR foams on an industrial scale, all experience shows that assumed that the thermal conductivities are about 3 mW/m ^* K lower. The reason for this is that experience has shown that PIR foams produced on an industrial scale have a finer cell structure and that the thermal conductivity of PIR foams produced on an industrial scale is determined according to the DIN EN 12667 standard at a measurement temperature of 10 °C.

The flame behavior was slightly better for the commercially available polyol 4, which can be explained by a higher oxygen content of polyol 1 due to the furan ring in the polyester backbone (compare Table 4, entries 1 and 2). Nevertheless, the PIR foam passed the flame behavior test for class B2 according to DIN 4102 and class E according to DIN EN ISO 11925-2 (experimental part).

Furthermore, the influence of 10 mol% bio-based aliphatic carboxylic acid from polyols 2 and 3 compared to polyol 1 in the PIR foams was only marginal. The density was slightly lower, the thermal conductivity and a _m with the same flame behavior was slightly increased.

Example 1

In a first process step of a process for synthesizing a polyol for producing PUR/PIR rigid foams according to exemplary embodiment 1, 121 mL diethylene glycol (136 g, 1.28 mol) as a polyhydric alcohol in a

500 mL three-neck flask, which is equipped with a KPG stirrer, is placed and preheated at 160° C. for 30 minutes. Then, in a second process step, 100 g of 2,5-furandicarboxylic acid (641 mmol, 1.00 eq.) as an aromatic dicarboxylic acid produced predominantly from renewable raw materials and 9.48 mL of tetraisopropyl orthotitanate (9.10 g, 32.0 mmol) as a titanium-containing Catalyst added to the three-necked flask. Based on the initial concentration of 2,5-furandicarboxylic acid corresponds in the present embodiment, the equivalent concentration of diethylene glycol has a value of 2.00 and the equivalent concentration of tetraisopropyl orthotitanate a value of 0.05. The reaction mixture thus obtained is then stirred at 160° C. and at speeds of 150 rpm and 450 rpm for 67 hours. The resulting condensate is distilled off continuously. The process according to exemplary embodiment 1 is summarized again in the following schematic reaction scheme:

The reaction process is followed by ¹ H-NMR and the reaction is stopped as soon as complete conversion of the 2,5-furandicarboxylic acid is observed. FIG. 3 shows the structural formula and the result of the ¹ FI-NMR of the polyol according to Example 1, measured in DMSO-d6.

The ¹ FI-NMR data are as follows:

¹ H NMR (500MHz, DMSO-d6): d/ppm = 7.28-7.44 (m, Hs),

4.61 (s, 0(CH2CH0H)2), 4.56 (s ^, ^OCH2CH2OH1 ), 4.38-4.44 (m, ^0CHCH2C40 ), 3.76-3.81 ₍ m, OCH26CH OCHO), 3.70-3.75 (m , OCH2 ³ CH OCHO), 3.45-

3.53 (m, ^OCH22CH22OH +0( _CHCH20H )2 ₎ , 3.38-3.43 (m, 0(0H20H0H)2).

Furthermore, a carbon-13 (C13) nuclear magnetic resonance was performed with the following results:

¹³ C-NMR (126MHz, DMSO-d6): d/ppm = 157.2-157.5, 146.0-146.2, 119.0-119.4, 72.37, 72.33, 64.55-64.65, 64.23-64.33, 60.32, 60.24.

In addition, an infrared spectroscopy is performed with the following results:

IR (ATR platinum diamond): v/cnr ¹ = 3394, 2873, 1716, 1581, 1509, 1452, 1382, 1271, 1223, 1120, 1060, 1020, 965, 924, 890, 827, 765, 618, 480. The polyol synthesized in this way is at least partially made from renewable raw materials. At least the aromatic dicarboxylic acid, which is 2,5-furandicarboxylic acid (FDCA), is predominantly produced from renewable raw materials to a proportion of at least 98% by weight. In addition, the polyhydric alcohol diethylene glycol is predominantly produced from renewable raw materials in a proportion of more than 50% by weight. The polyol has an OFI number of more than 250 mg KOFI/g and less than 400 mg KOFI/g. In the present case, an OFI number of the polyol is 322 mg KOFI/g. The polyol has a free glycol content of more than 6% by weight and less than 20% by weight, based on its total mass. The polyol has an average molar mass of less than 1000 g/mol. In the present case, the mean molar mass of the polyol is 870 g/mol. The polyol has a dynamic viscosity between 3,000 mPas and 12,000 mPas.

A PUR/PIR rigid foam is then produced from the polyol synthesized by means of the process by means of a process for the production of PUR/PIR flat foams together with methylenediphenyl isocyanate (MDI) as the polyisocyanate and pentane as the blowing agent. The PUR/PIR rigid foam produced using this process has a bulk density of 30.2 kg/m ³ . A measured thermal conductivity of the PUR/PIR rigid foam is 0.0209 W/(mK), the measured value was determined at an average temperature of 23 °C on the laboratory foam. System foams, measured at an average temperature of 10 °C, have a thermal conductivity that is approx. 0.002 to 0.003 W/(mK) lower. The fire behavior of the PUR/PIR rigid foam produced corresponds to building material class E in accordance with DIN EN ISO 11925-2.

Example 2

In a first step of a method for the synthesis of a polyol for the production of PUR / PIR rigid foams according to Example 2, 5.31 mL diethylene glycol (corresponds to 5.95 g, 56.1 mmol) as a polyhydric alcohol in a 50 mL round bottom flask, which with equipped with a magnetic stirrer is presented and preheated for 30 minutes at 160 °C. Subsequently, in a second process step of the process, 5.00 g of 2,5-furandicarboxylic acid (32.0 mmol, 1.00 eq.) and 474 ml of tetraisopropyl orthotitanate (455 mg, 1.60 mmol) are added as titanium-containing catalyst. In contrast to the previous exemplary embodiment, in the present exemplary embodiment 2 the equivalent concentration of the diethylene glycol based on the concentration of the 2,5-furandicarboxylic acid corresponds to a value of 1.75. The equivalent concentration of the tetraisopropyl orthotitanate based on the concentration of the 2,5-furandicarboxylic acid corresponds unchanged to a value of 0.05. The reaction mixture is then stirred at 160° C. for 26 hours. The resulting condensate is distilled off continuously. The process according to exemplary embodiment 2 is summarized again in the following schematic reaction scheme:

The polyol synthesized using the method is at least partially made from renewable raw materials. At least the aromatic dicarboxylic acid, which is 2,5-furandicarboxylic acid (FDCA), is predominantly produced from renewable raw materials to a proportion of at least 97% by weight. In addition, the polyhydric alcohol diethylene glycol is predominantly produced from renewable raw materials in a proportion of more than 50% by weight. Polyol has an OFI number of more than 250 mg KOFI/g and less than 400 mg KOFI/g. The polyol has a free glycol content of more than 6% by weight and less than 20% by weight, based on its total mass. The polyol has an average molar mass of less than 1000 g/mol. In the present case, the polyol has an average molar mass of 760 g/mol. The polyol has a dynamic viscosity between 3,000 mPas and 12,000 mPas. A PUR-PIR rigid foam with the corresponding properties can be produced from the synthesized polyol together with at least one polyisocyanate and at least one blowing agent by means of a process for the production of PUR/PIR rigid foams described at the outset.

Example 3

In a first process step of a process for synthesizing a polyol for producing PUR/PIR rigid foams according to exemplary embodiment 3, 5.31 mL diethylene glycol (5.95 g, 56.1 mmol) is placed in a 50 mL round bottom flask equipped with a magnetic stirrer is presented and preheated for 30 minutes at 160°C. In a subsequent second process step of the process, 5.00 g of 2,5-furandicarboxylic acid (32.0 mmol, 1.00 eq.) As an aromatic dicarboxylic acid predominantly produced from renewable raw materials in a proportion of at least 98% by weight and 474 mL of tetraisopropyl orthotitanate (455 mg, 1.60 mmol) were added as titanium-containing catalyst. In addition, in the second step of the process, a surfactant is added, which is predominantly produced from renewable raw materials in a proportion of more than 50% by weight, namely 1.21 mL polyethylene glycol dodecyl ether (1.16 g, 3.20 mmol) , which is available under the trade name Brij® L4 mainly from renewable raw materials. Based on the initial concentration of 2,5-furandicarboxylic acid, the equivalent concentration of diethylene glycol in the present embodiment corresponds to a value of 1.75, the equivalent concentration of tetraisopropyl orthotitanate to a value of 0.05 and the equivalent concentration of polyethylene glycol dodecyl ether to a value of 0.10. In the second process step, the reaction mixture is then stirred at 160° C. for 32 hours and at speeds of 150 rpm and 450 rpm. The resulting condensate is distilled off continuously. The process according to exemplary embodiment 3 is summarized again in the following schematic reaction scheme:

The polyol synthesized using the method is at least partially made from renewable raw materials. At least the aromatic dicarboxylic acid, which is 2,5-furandicarboxylic acid (FDCA), is predominantly produced from renewable raw materials to a proportion of at least 98% by weight. In addition, the polyhydric alcohol diethylene glycol is predominantly produced from renewable raw materials in a proportion of more than 50% by weight. The polyol has an OFI number of more than 250 mg KOFI/g and less than 400 mg KOFI/g. The polyol has a free glycol content of more than 6% by weight and less than 20% by weight, based on its total mass. The polyol has an average molar mass of less than 1000 g/mol. In the present case, the polyol has an average molar mass of 800 g/mol. The polyol has a dynamic viscosity between 3,000 mPas and 12,000 mPas. In the present case, the polyol has a dynamic viscosity of between 4,000 mPas and 8,000 mPas

A PUR-PIR flat foam with the corresponding properties can be produced from the synthesized polyol together with at least one polyisocyanate and at least one blowing agent by means of a process according to the invention for the production of PUR/PIR flat foams described at the outset.

Example 4

In a first process step of a process for synthesizing a polyol for the production of PUR/PIR flat foams according to exemplary embodiment 4, 6.07 mL diethylene glycol (6.80 g, 64.1 mmol) are placed in a 50 mL round bottom flask equipped with a magnetic stirrer is presented and preheated for 30 minutes at 160 °C. Subsequently, in a second process step of the process, 4.00 g of 2,5-furandicarboxylic acid (25.6 mmol, 0.80 eq.) As an aromatic dicarboxylic acid produced predominantly from renewable raw materials and in addition, another dicarboxylic acid, specifically 757 mg of succinic acid (6.41 mmol, 0.20 eq.), which is mainly produced from renewable raw materials, is added. In addition, in the second process step, 474 ml of tetraisopropyl orthotitanate (455 mg, 1.60 mmol) are added as titanium-containing catalyst. Based on the initial concentration of the dicarboxylic acids, the equivalent concentration of the diethylene glycol corresponds to a value of 2.00 and the equivalent concentration of the tetraisopropyl orthotitanate to a value of 0.05 in the present exemplary embodiment. The reaction mixture thus obtained is then stirred for 44 hours at 160° C. and at speeds of 150 rpm and 450 rpm. The resulting condensate is distilled off continuously. The process according to exemplary embodiment 1 is summarized again in the following schematic reaction scheme:

The polyol synthesized in this way is at least partially made from renewable raw materials. At least the aromatic dicarboxylic acid, which is 2,5-furandicarboxylic acid (FDCA), is predominantly produced from renewable raw materials to a proportion of at least 98% by weight. In addition, the polyhydric alcohol diethylene glycol is predominantly produced from renewable raw materials in a proportion of more than 50% by weight. The polyol has an OFI number of more than 250 mg KOFI/g and less than 400 mg KOFI/g. The polyol has a free glycol content of more than 6% by weight and less than 20% by weight, based on its total mass. The polyol has an average molar mass of less than 1000 g/mol. The polyol has a dynamic viscosity between 3,000 mPas and 12,000 mPas. In the present case, the polyol has a dynamic viscosity of between 4,000 mPas and 8,000 mPas. The polyol is at least partially synthesized from at least one other dicarboxylic acid, the other dicarboxylic acid being present Succinic acid is an aliphatic dicarboxylic acid which is predominantly produced from renewable raw materials in a proportion greater than 50% by weight.

A PUR-PIR rigid foam with the corresponding properties can be produced from the synthesized polyol together with at least one polyisocyanate and at least one blowing agent by means of a process for the production of PUR/PIR rigid foams described at the outset.

Example 5

In a first process step of a process for synthesizing a polyol for producing PUR/PIR rigid foams according to exemplary embodiment 5, 6.07 mL diethylene glycol (6.80 g, 64.1 mmol) is placed in a 50 mL round bottom flask equipped with a magnetic stirrer is presented and preheated for 30 minutes at 160 °C. In a second process step of the process, 4.00 g of 2.5 furandicarboxylic acid (25.6 mmol, 0.80 eq.) as an aromatic dicarboxylic acid produced predominantly from renewable raw materials and, in addition, another aromatic dicarboxylic acid, namely 1.06 g of phthalic acid (6th .41 mmol, 0.20 eq.) added. In addition, 474 ml of tetraisopropyl orthotitanate (455 mg, 1.60 mmol) are added as titanium-containing catalyst. Based on the initial concentration of the dicarboxylic acids, the equivalent concentration of the diethylene glycol corresponds to a value of 2.00 and the equivalent concentration of the tetraisopropyl orthotitanate to a value of 0.05 in the present exemplary embodiment. The reaction mixture thus obtained is then stirred at 160° C. and at speeds of 150 rpm and 450 rpm for 51 hours.

The resulting condensate is distilled off continuously. The process according to exemplary embodiment 1 is summarized again in the following schematic reaction scheme: The polyol synthesized using the method is at least partially made from renewable raw materials. At least the aromatic dicarboxylic acid, which is 2,5-furandicarboxylic acid (FDCA), is predominantly produced from renewable raw materials to a proportion of at least 98% by weight. In addition, the polyhydric alcohol diethylene glycol is predominantly produced from renewable raw materials in a proportion of at least 50% by weight. The polyol is at least partially synthesized from at least one other dicarboxylic acid, which in this case is phthalic acid. The polyol has an OFI number of more than 250 mg KOFI/g and less than 400 mg KOFI/g. The polyol has a free glycol content of more than 6% by weight and less than 20% by weight, based on its total mass. The polyol has an average molar mass of less than 1000 g/mol. The polyol has a dynamic viscosity between 3,000 mPas and 12,000 mPas. In the present case, the polyol has a dynamic viscosity of between 4,000 mPas and 8,000 mPas.

A PUR-PIR flart foam with the corresponding properties can be produced from the synthesized polyol together with at least one polyisocyanate and at least one blowing agent by means of a process for the production of PUR/PIR fl art foams described above.

Example 6

In a first process step of a process for synthesizing a polyol for the production of PUR/PIR flat foams according to exemplary embodiment 6, 6.07 mL diethylene glycol (6.80 g, 64.1 mmol) are placed in a 50 mL round bottom flask equipped with a magnetic stirrer is presented and preheated for 30 minutes at 160°C. In a second process step of the process, 5.00 g of 2,5-furandicarboxylic acid (32.0 mmol, 1.00 eq.) are then added.

In contrast to the previous exemplary embodiments, 551 ml of titanium tetrabutanolate (545 mg, 1.60 mmol) are added as titanium-containing catalyst in the second process step. Based on the initial concentration of 2,5-Furandicarboxylic acid corresponds in the present embodiment to the equivalent concentration of diethylene glycol to a value of 2.00 and the equivalent concentration of titanium tetrabutanolate to a value of 0.05. The reaction mixture thus obtained is then stirred at 160° C. and at speeds of 150 rpm and 450 rpm for 32 hours. The process according to exemplary embodiment 6 is summarized again in the following schematic reaction scheme:

The polyol synthesized using the method is at least partially made from renewable raw materials. At least the aromatic dicarboxylic acid, which is 2,5-furandicarboxylic acid (FDCA), is predominantly produced from renewable raw materials to a proportion of at least 98% by weight. In addition, the polyhydric alcohol diethylene glycol is predominantly produced from renewable raw materials in a proportion of more than 50% by weight. The polyol has an OFI number of more than 250 mg KOFI/g and less than 400 mg KOFI/g. The polyol has a free glycol content of more than 6% by weight and less than 20% by weight, based on its total mass. The polyol has an average molar mass of less than 1000 g/mol. The polyol has a dynamic viscosity between 3,000 mPas and 12,000 mPas. In the present case, the polyol has a dynamic viscosity of between 4,000 mPas and 8,000 mPas.

A PUR-PIR flart foam with the corresponding properties can be produced from the synthesized polyol together with at least one polyisocyanate and at least one blowing agent by means of a process for the production of PUR/PIR fl art foams described above. Example 7

In a first process step of a process for synthesizing a polyol for producing PUR/PIR rigid foams according to exemplary embodiment 7, 6.07 mL diethylene glycol (6.80 g, 64.1 mmol) is placed in a 50 mL round bottom flask equipped with a magnetic stirrer is presented and preheated for 30 minutes at 160°C. In a second process step of the process, 5.00 g of 2,5-furandicarboxylic acid (32.0 mmol, 1.00 eq.) are added as an aromatic dicarboxylic acid produced predominantly from renewable raw materials. In contrast to the previous exemplary embodiments, in the second method step of the method according to exemplary embodiment 7, 551 ml_399 mg of dibutyltin(IV) oxide (1.60 mmol) are added as catalyst. Based on the starting concentration of the 2,5-furandicarboxylic acid, the equivalent concentration of the diethylene glycol corresponds to a value of 2.00 and the equivalent concentration of the dibutyltin(IV) oxide to a value of 0.05 in the present exemplary embodiment. The reaction mixture thus obtained is then stirred at 160° C. and at speeds of 150 rpm and 450 rpm for 7.5 hours. The process according to exemplary embodiment 7 is summarized again in the following schematic reaction scheme:

The polyol synthesized using the method is at least partially made from renewable raw materials. At least the aromatic dicarboxylic acid, which is 2,5-furandicarboxylic acid (FDCA), is predominantly produced from renewable raw materials to a proportion of at least 98% by weight. In addition, the polyhydric alcohol diethylene glycol is predominantly produced from renewable raw materials in a proportion of more than 50% by weight. The polyol has a OH number greater than 250 mg KOH/g and less than 400 mg KOH/g. The polyol has a free glycol content of more than 6% by weight and less than 20% by weight, based on its total mass. The polyol has an average molar mass of less than 1000 g/mol. The polyol has a dynamic viscosity between 3,000 mPas and 12,000 mPas. In the present case, the polyol has a dynamic viscosity of between 4,000 mPas and 8,000 mPas.

Example 8

In a first process step of a process for the synthesis of a polyol for the production of PUR/PIR rigid foams according to exemplary embodiment 8, 121 mL diethylene glycol (136 g, 1.28 mol, 2.00 eq.) is placed in a 500 mL three-necked flask with a mechanical stirrer and distillation bridge and preheated to 160°C for 30 minutes. Subsequently, in a second process step of the process, 9.48 mL tetraisopropyl orthotitanate (9.10 g,

32.0 mmol, 0.05 eq.) as a titanium-containing catalyst, 90.0 g 2,5-furandicarboxylic acid (577 mmol, 0.90 eq.) as an aromatic dicarboxylic acid produced mainly from renewable raw materials and 7.57 g succinic acid (64 .1 mmol, 0.10 eq.), which is mainly produced from renewable raw materials, is added as a further dicarboxylic acid and the reaction mixture is stirred while the condensate is continuously removed by distillation. The reaction process is followed by 1 H NMR and the reaction is stopped as soon as complete conversion of FDCA is observed. FIG. 4 shows the structural formula and the result of the ¹ H-NMR of the polyol according to Example 8, measured in DMSO-d6.

The ¹ H-NMR data are as follows: ¹ H-NMR (500MHz, DMSO-d6): d/ppm = 7.28-7.44 (m, H ⁵ ),

4.61 (s, 0( ^CH2CH0H )2), 4.56 ( _s , ^OCH2CH2OH1 ), 4.38-4.44 ₍ m, 0CHCH240), 4.09-4.16 (m, ^0CHCH280 ), 3.76-3.81 ( m, _OCH2 ⁶ _CH2 OCHO), 3.70-3.75 (m ^, _OCH2 ³ _CH2 OCHO), 3.62-3.68 ( ^m , OCH2 ⁷ _CH2 OCHO), 3.45-3.53 (m, OCH2 ₂ CH2 ₂ OH + 0( _CH2 _CH2 0H)2), 3.38-3.43 (m, 0( _CH2 _CH2 0H)2).

^13C -NMFt (126MHz, DMSO-d6): d/ppm = 171.9-172.0, 157.2-157.5, 146.0-146.2,

131.3-131.8, 119.0-119.4, 72.4, 72.3, 68.0-68.2, 64.7-64.8,64.5-64.7, 64.2-64.4, 63.6, 63.4, 62.9, 60.3, 60.2.

Infrared spectroscopy was also performed with the following results:

IR (ATR platinum diamond): v/cnr ¹ = 3407, 2874, 1716, 1581, 1509, 1452, 1382,

1271, 1224, 1120, 1062, 1020, 964, 924, 889, 827, 764, 618, 479.

Example 9

In a first process step of a process for the synthesis of a polyol for the production of PUR/PIR rigid foams according to exemplary embodiment 9, 121 mL diethylene glycol (136 g, 1.28 mol) as a polyhydric alcohol is placed in a 500 mL three-necked flask with a mechanical stirrer and distillation bridge and 30 Preheated to 160°C for minutes. Subsequently, in a second process step of the process, 9.48 mL tetraisopropyl orthotitanate (9.10 g, 32.0 mmol, 0.05 eq.) as titanium-containing catalyst, 90.0 g 2,5-furandicarboxylic acid (577 mmol, 0.90 eq. ) as an aromatic dicarboxylic acid produced predominantly from renewable raw materials and 9.36 g of adipic acid (64.1 mmol, 0.10 eq.), which is predominantly produced from renewable raw materials, added and the reaction mixture stirred while the condensate is continuously passed through distillation is removed. The reaction process is followed by 1 H NMR and the reaction is stopped as soon as complete conversion of FDCA is observed. FIG. 5 shows the structural formula and the result of the ¹ H-NMR of the polyol according to Example 9, measured in DMSO-d6.

The ¹ H-NMR data are as follows:

¹ H-NMR (500 MHz, DMSO-de): d/ppm = 7.28-7.44 (m, H ⁵ ),

4.61 (s, 0( _CH2CH0H )2), 4.56 ( _t , ^0CH2CH20H1 ), 4.38-4.44 (m, ^0CHCH240 ), 4.09-4.15 (m, ^0CHCH280 ), 3.76-3.81 ( m, OCH ₂ ⁶ CH ₂ OCHO), 3.70-3.75 (m, OCH ₂ ³ CH ₂ OCHO), 3.62-3.68 (m, OCH ₂ ⁷ CH ₂ OCHO), 3.45-3.53 (m, OCH ₂ ² CH ₂ ² OH + O( _CH2 _CH2 OH)2), 3.38-3.43 (m, O( _CH2 _CH2 OH)2).

¹³ C-NMR (126MHz, DMSO-d6): d/ppm = 172.6-172.8, 157.2-157.5, 145.9-146.2,

131.3-131.8, 119.0-119.4, 72.4, 72.3, 67.9-68.3, 64.6-64.7,64.2-64.4, 62.8-63.2, 60.3, 60.2.

Infrared spectroscopy was also performed with the following results:

IR (ATR platinum diamond): v/cnr ¹ = 3402, 2873, 1716, 1581, 1509, 1453, 1382,

1271, 1224, 1220, 1061, 1021, 964, 924, 889, 827, 765, 618, 481.

Example 10

In a first process step of a process for the synthesis of a polyol for the production of PUR/PIR rigid foams according to exemplary embodiment 10, 121 mL diethylene glycol (136 g, 1.28 mol, 2.00 eq.) is placed in a 500 mL three-necked flask with a mechanical stirrer and distillation bridge and preheated to 160°C for 30 minutes. Then in a second Process step of the process 9.48 mL of tetraisopropyl orthotitanate (9.10 g,

32.0 mmol, 0.05 eq.) as a titanium-containing catalyst, 80.0 g 2,5-furandicarboxylic acid (513 mmol, 0.80 eq.) as an aromatic dicarboxylic acid produced predominantly from renewable raw materials and 21.3 g phthalic acid (128 mmol,

0.20 eq.) is added as a further aromatic dicarboxylic acid and the reaction mixture is stirred while the condensate is continuously removed by distillation. The reaction process is followed by 1 H NMR and the reaction is stopped as soon as complete conversion of FDCA is observed. FIG. 6 shows the structural formula and the result of the ¹ FI-NMR of the polyol according to Example 10, measured in DMSO-d6.

The ¹ FI-NMR data are as follows:

¹ H-NMR (500 MHz, DMSO-d6): d/ppm = 7.58-7.78 (m, H ⁹ ), 7.28-7.44 (m, H ⁵ ),

4.61 (s, 0( _CH2CH0H ) ² ), 4.56 ( _s , ^OCH2CH2OH1 ), 4.38-4.44 (m, 0CHCH240), 4.30-4.38 (m, ^0CHCH280 ), 3.76-3.81 ( m, OCH ₂ ⁶ CH ₂ OCHO), 3.70-3.75 (m, OCH ₂ ³ CH ₂ OCHO), 3.65-3.70 (m, OCH ₂ ⁷ CH ₂ OCHO), 3.45-3.53 (m, OCH ₂ ² CH ₂ ² OH + O( _CH2 _CH2 OH)2), 3.38-3.43 (m, O( _CH2 _CH2 OH)2).

¹³ C-NMR (126MHz, DMSO-d6): d/ppm = 166.8-167.0, 157.2-157.5, 146.0-146.2,

131.3-131.8, 128.6-128.8, 119.0-119.4, 72.4, 72.3, 68.0-68.2, 64.7-64.8,64.5-64.7,

64.3-64.4, 64.2-64.3, 60.3, 60.2.

Infrared spectroscopy was also performed with the following results:

IR (ATR platinum diamond): v/crrr ¹ = 3402, 2874, 1716, 1581, 1509, 1451, 1381, 1271, 1224, 1119, 1065, 1021, 964, 924, 889, 827, 765, 705, 618.5 480

Claims

Expectations

1. PUR/PIR rigid foam produced from at least one polyol which is synthesized from at least one polyhydric alcohol and at least one aromatic dicarboxylic acid, characterized in that the polyol is produced at least partially from renewable raw materials.

2. PUR/PIR rigid foam according to claim 1, characterized in that at least the aromatic dicarboxylic acid is predominantly produced from renewable raw materials.

3. PUR/PIR rigid foam according to claim 2, characterized in that the aromatic dicarboxylic acid is 2,5-furandicarboxylic acid (FDCA), which is predominantly produced from renewable raw materials.

4. PUR/PIR rigid foam according to one of the preceding claims, characterized in that at least the polyhydric alcohol is predominantly made from renewable raw materials.

5. PUR/PIR rigid foam according to one of the preceding claims, characterized in that the polyol has an OH number greater than 250 mg KOH/g.

6. PUR/PIR rigid foam according to one of the preceding claims, characterized in that the polyol has a free glycol content of greater than 6% by weight, based on the total mass of the polyol.

7. PUR/PIR rigid foam according to one of the preceding claims, characterized in that the polyol has an average molar mass of less than 1000 g/mol.

8. PUR/PIR rigid foam according to one of the preceding claims, characterized in that the polyol is at least partially synthesized from at least one other dicarboxylic acid.

9. PUR/PIR rigid foam according to claim 8, characterized in that the further dicarboxylic acid is an aliphatic dicarboxylic acid which is predominantly produced from renewable raw materials.

10. PUR/PIR rigid foam according to one of the preceding claims, characterized in that the polyol has a dynamic viscosity of between 3,000 mPas and 12,000 mPas.

11. PUR/PIR rigid foam according to one of the preceding claims, characterized by a thermal conductivity of between 0.018 W/(mK) and 0.021 W/(mK).

12. Process for the synthesis of a polyol for the production of PUR/PIR rigid foams, in particular according to one of the preceding claims, from at least one polyhydric alcohol and at least one aromatic dicarboxylic acid, characterized in that renewable raw materials are at least partially used as starting materials.

13. The method according to claim 12, characterized in that at least one aromatic dicarboxylic acid, which is mainly produced from renewable raw materials, is used.

14. The method according to claim 13, characterized in that 2,5-furandicarboxylic acid (FDCA), which is mainly produced from renewable raw materials, is used as the aromatic dicarboxylic acid.

15. The method according to claim 14, characterized in that diethylene glycol (DEG) is used as the polyhydric alcohol and the method is carried out according to the following generalized reaction scheme: where n can, in particular, assume positive values between 1.0 and 10.0 and x can assume, in particular, positive values between 0.0 and 5.0.

16 The method according to any one of claims 12 to 15, characterized in that at least one polyhydric alcohol which is mainly produced from renewable raw materials is used.

17. The method according to any one of claims 12 to 16, characterized in that at least one catalyst is used.

18. The method according to claim 17, characterized in that a titanium-containing catalyst is used as the catalyst.

19. The method according to any one of claims 12 to 18, characterized in that the polyhydric alcohol is used in an equivalent concentration of between 1.75 and 2.00, based on an initial concentration of dicarboxylic acid(s).

20. The method according to any one of claims 12 to 19, characterized in that a reaction mixture of the starting materials is stirred at a temperature between 60 °C and 240 °C.

21. The method according to any one of claims 12 to 20, characterized in that in addition at least one further dicarboxylic acid is used.

22. The method according to any one of claims 12 to 21, characterized in that in addition at least one surfactant, which is mainly produced from renewable raw materials, is used.

23. A polyol synthesized by a method according to any one of claims 12 to 22.

24. The polyol of claim 23, characterized in that the polyol is poly(diethylene glycol furanoate) (PDEF), which has the following generalized structure:

, where n can in particular assume positive values between 1.0 and 10.0.

25. Process for the production of PUR/PIR rigid foams, in particular according to one of Claims 1 to 11, in which at least one polyisocyanate, at least one polyol which is at least partially synthesized from renewable raw materials, in particular according to Claim 22, and at least one blowing agent to form a PUR/PIR -Hard foam are implemented.