Foam formulation for an insulation panel

Abstract

A foam formulation for producing a rigid polyisocyanurate foam comprises: - a polyester polyol, wherein at least 85 weight percent of the polyester polyol is formed by sustainable polyester polyol; - a blowing agent. wherein the blowing agent comprises water and an additional blowing agent; - at least one surfactant; - a catalyst; - a flame-retardant additive; - a polyisocyanate, preferably a polymeric methylene diphenyl diisocyanate.

Description

[0001] Foam formulation for an insulation panel

[0002] The invention relates to a formulation the production of an insulation panel from rigid polyisocyanurate foam and insulation panels produced with such foam formulations.

[0003] W02020 / 076529A1 describes a formulation for the production of polyisocyanurate insulation panels. The formulation comprises a polyester polyol having a hydroxyl number between 150 and 600 mg KOH / gram and a functionality of at least 2, a blowing agent comprising water and an additional blowing agent, a non-silicone organic surfactant, between 0.1 and 3.7 weight percent of a cyclic siloxane by total weight of the foam formulation, a catalyst, optionally a flame-retardant additive, and a polyisocyanate having an isocyanate index between 100 and 500. W02020 / 076529A1 further describes a rigid polyurethane foam produced with such a formulation and a method for producing a rigid polyurethane foam.

[0004] Isocyanurate insulation panels must meet a series of criteria. First, they must have a good thermal insulation value, which is classically expressed as the lambda value (in W / (m*K)), initially and during the useful life of the insulation panel. Furthermore, such thermal insulation panels must also have a good rigidity and a sufficient flame-retardant effect. Preferably, the density is low, so that costs are low because less raw material is required to produce the polyisocyanurate insulation panel.

[0005] It is an object of the invention to solve problems of foam formulations and of state of the art polyisocyanurate insulation panels.

[0006] A specific objective of the invention is to provide for a more sustainable foam formulation for the production of polyisocyanurate insulation panels.

[0007] This objective is achieved by the invention as described in the claims. The objective is achieved by using sustainably produced polyol - with bio-based and / or recycled raw material - and by making the polyisocyanurate foam and polyisocyanurate insulation panels according to the invention easier and more sustainable to recycle. Furthermore, the polyisocyanurate foam has an excellent thermally insulating value, allowing thinner polyisocyanurate insulation panels to be used to achieve the same thermal insulating effect.

[0008] The first aspect of the invention relates to a foam formulation for producing a rigid polyisocyanurate foam. The foam formulation comprises:

[0009] - a polyester polyol, wherein at least 85 weight percent of the polyester polyol is formed by sustainable polyester polyol;

[0010] - a blowing agent, wherein the blowing agent comprises water and an additional blowing agent;

[0011] - at least one surfactant;

[0012] - a catalyst;

[0013] - a flame-retardant additive;

[0014] - a polyisocyanate, preferably a polymeric methylene diphenyl diisocyanate.

[0015] The use of the sustainable polyester polyol in the foam formulation ensures the sustainable nature of the polyisocyanurate foam produced with this foam formulation. The polyisocyanurate foam produced with this foam formulation can be recycled, producing new polyester polyol for the production of new rigid polyisocyanurate foam. Recycling can be carried out as described in WO2024 / 161203A1.

[0016] The polyester polyol preferably has a viscosity - measured at 25°C - of between 3000 and 4000 mPa.s. This ensures the good processability of the polyester polyol during the production of the polyisocyanurate foam, which means less energy is required in this production.

[0017] Preferably, at least 90 weight percent, and more preferably at least 100 weight percent, of the polyester polyol is formed by sustainable polyester polyol. In a preferred embodiment of the invention, the sustainable polyester polyol is selected from polyester polyol produced from recycled polyester or from polyester polyol produced from a bio-based raw material, or from combinations thereof.

[0018] Polyester polyol produced from recycled polyester can be produced from, for example, recycled polyethylene terephthalate.

[0019] Polyester polyol produced from recycled polyethylene terephthalate (PET) can be produced from various sources of polyethylene terephthalate, for example from recycled PET bottles. After purifying the recycled polyethylene terephthalate, a chemical depolymerization process can be performed, for example by means of glycolysis. In glycolysis the polyethylene terephthalate reacts with a glycol (e.g. with ethylene glycol or diethylene glycol) at elevated temperatures. Hereby bi s(hydroxy alkyl) terephthalates and other intermediates are formed. After purification further reaction with glycols can take place to achieve the desired molecular weight and hydroxyl number of the polyester polyol. This process can also be performed on polyesters other than polyethylene terephthalate.

[0020] Polyester polyol produced from bio-based raw materials can be produced from vegetable raw material. Raw materials that may be used for this include biomass, starch containing products (e.g. com), sugar containing products, cellulose containing products, vegetable oils (e.g. rapeseed oil or sunflower oil), or waste from processes involving production or processing of vegetable products, for example waste or byproducts from the agricultural or food industries.

[0021] Polyester polyol can be obtained from vegetable oil (e.g. rapeseed oil or sunflower oil) by subjecting the vegetable oil to an epoxidation step, where unsaturated carbon-carbon bonds in the oil are converted into epoxides. This step can be performed by means of a peracid. A next step is a ring-opening reaction of the epoxide, for which alcohols such as methanol, ethanol, or isopropanol can be used. Hereby hydroxyl groups are introduced into the molecule. A next step is the reaction with a dicarboxylic acid or with an anhydride (e.g. phthalic anhydride) to form the polyester polyol. The alcohols used can be obtained from bio-based raw materials. Furthermore, dicarboxylic acids or anhydrides produced from bio-based raw materials can be used.

[0022] For example, succinic acid obtained from biomass or sebacic acid obtained from castor oil can be used as the dicarboxylic acid. For example, 1,3 -propanediol obtained by a fermentation method, or 1,10-decanediol derived from castor oil can be used as diol in the production of sustainable polyester polyol for use in the invention.

[0023] Polyester polyol can be obtained from biomass and vegetable products according to the method described in US2018 / 0037692A1. US2018 / 0037692A1 describes methods for producing both the dicarboxylic acid and the diols that are used in the production of polyester polyols from biomass.

[0024] Preferably, the sustainable polyester polyol is a combination of polyester polyol produced from recycled polyester - for example from recycled polyethylene terephthalate (PET) - and of polyester polyol produced from a bio-based raw material, for example from a vegetable raw material.

[0025] Surprisingly, the inventors noticed that the combination of polyester polyol produced from recycled polyester (for example from recycled polyethylene terephthalate) and polyester polyol produced from bio-based raw materials leads to excellent results of polyisocyanurate foam made with the foam formulation according to the invention, with regard to insulation value and rigidity of the polyisocyanurate foam. Polyester polyol produced from recycled polyester (for example from recycled polyethylene terephthalate) and polyester polyol produced from bio-based raw materials are different in composition and properties, and it was found that their combination results in polyisocyanurate foam with improved properties.

[0026] Preferably, the sustainable polyester polyol comprises between 20 and 60 weight percent of polyester polyol produced from recycled polyester (for example from recycled polyethylene terephthalate), and between 40 and 80 weight percent of polyester polyol produced from a bio-based raw material. Such a combination of sustainable polyol produced from recycled polyester and polyester polyol produced from bio-based raw material was found to result in optimal properties of polyisocyanurate foam produced with the foam formulation.

[0027] More preferably, the sustainable polyester polyol comprises between 25 and 35 weight percent of polyester polyol produced from recycled polyester (for example from recycled polyethylene terephthalate), and between 65 and 75 weight percent of polyester polyol produced from bio-based raw material. Such a sustainable polyester polyol resulted in polyisocyanurate foam with even better properties.

[0028] Preferably, at least 50 weight percent, and preferably at least 60 weight percent, of the raw material of the polyester polyol is comprised of bio-based raw material.

[0029] This weight percentage can be determined according to ASTM D6866-22.

[0030] Preferably, at least 20 weight percent, and preferably at least 25 weight percent, of the raw material of the polyester polyol is comprised of polyester polyol from recycled polyester, more preferably from recycled polyethylene terephthalate.

[0031] This weight percent can be determined according to ISO 14021 :2016.

[0032] Preferably, at least 90 weight percent, and preferably at least 95 weight percent, of the raw material of the polyester polyol is comprised of bio-based raw material or recycled polyester (for example recycled polyethylene terephthalate), or of a combination of biobased raw material and recycled polyester.

[0033] The isocyanate index of the foam formulation is preferably higher than 320 and lower than 400, more preferably the isocyanate index of the foam formulation is lower than 360. More preferably, the isocyanate index of the foam is higher than 330. Foam formulations with such an isocyanate index have been found to result in a good combination of properties - particularly with regard to insulation value and rigidity - of the polyisocyanurate foam at a low density of the polyisocyanurate foam.

[0034] As is common in polyurethane and polyisocyanurate formulations, the isocyanate index is defined as the number of isocyanate groups in the formulation divided by the number of hydroxyl groups in the formulation, multiplied by 100. Isocyanate index values higher than 100 indicate an excess of isocyanate groups in the formulation relative to the number of hydroxyl groups. Polyisocyanurate formulations have an isocyanate index higher than 100 to form polyisocyanurate groups during the foaming reaction by reaction of isocyanate groups with isocyanate groups. However, in this embodiment the isocyanate index value is chosen to be higher than usual for polyisocyanurate formulations.

[0035] A preferred embodiment of the invention is characterized in that the hydroxyl number of the polyester polyol is between 220 and 260 mg KOH / gram.

[0036] Such hydroxyl numbers synergistically ensure a polyisocyanurate foam with good insulating effect and high rigidity at low density.

[0037] The polyester polyol used preferably has a functionality of at least 2, and more preferably of less than 2.3, more preferably of less than 2.2. Such hydroxyl numbers synergistically ensure a polyisocyanurate foam with good insulating effect and high rigidity at low density.

[0038] The blowing agent preferably comprises a pentane, with the pentane comprising at least 85 weight percent - and preferably at least 95 weight percent - of cyclopentane.

[0039] Pentane exists in various isomers: n-pentane, cyclopentane, neopentane (2,2-dimethyl propane), and isopentane (2 -methyl butane). The selection of cyclopentane was found to be beneficial to the insulation value of the insulation panel. This means that a thinner insulation panel can be used for the same insulation value. This means an insulation panel with lower weight, which is therefore more sustainable. A foam formulation wherein the blowing agent comprises pentane, with at least 85 weight percent - and more preferably at least 95 weight percent - of the pentane being cyclopentane, and with the isocyanate index being higher than 320 and lower than 400, more preferably lower than 360, is preferred.

[0040] This embodiment achieved a good combination of insulation value and rigidity at a low polyisocyanurate foam density, which is advantageous for the sustainability of the polyisocyanurate insulation panel.

[0041] Insulation panels with lower densities for a given thermal insulation value are also more sustainable because their transport requires less energy.

[0042] Preferably, the blowing agent does not comprise isopentane. Such embodiments result in a polyisocyanurate foam with improved thermal insulation value.

[0043] Preferably, the foam formulation comprises at least 2 weight percent of cyclopentane, more preferably at least 3 weight percent of cyclopentane, more preferably at least 4 weight percent of cyclopentane, and even more preferably at least 4.5 weight percent of cyclopentane.

[0044] A preferred foam formulation is characterized in that the flame retardant contains or is comprised of triethyl phosphate (TEP).

[0045] The flame retardant preferably does not contain tris(2-chloropropyl) phosphate (TCPP).

[0046] These embodiments synergistically contribute to the sustainability of the produced polyisocyanurate due to not using the carcinogenic tris(2-chloropropyl) phosphate (TCPP) to achieve sufficient and effective flame retardancy of the polyisocyanurate foam. The second aspect of the invention relates to a rigid polyisocyanurate foam. The rigid polyisocyanurate foam is characterized in that it is obtained with a foam formulation according to any embodiment of the foam formulation according to the first aspect of the invention.

[0047] The polyisocyanurate foam preferably has closed cells.

[0048] The polyisocyanurate is formed by reaction of the polyester polyol with the polyisocyanate. The water and the additional blowing agent ensure the formation of a foam that preferably has closed cells.

[0049] The rigid polyisocyanurate foam preferably has a density between 28 and 35 kg / m3, more preferably between 30 and 33 kg / m3.

[0050] The third aspect of the invention is a thermal insulation panel. The thermal insulation panel is characterized in that it comprises a core from polyisocyanurate foam according to any embodiment of the second aspect of the invention. The core from rigid polyisocyanurate foam is foamed between two facers, preferably between gas-tight facers.

[0051] Preferably, the core from rigid polyisocyanurate foam contacts both of the facers.

[0052] Preferably, each of two facers is an aluminum sheet. Optionally, the aluminum sheet comprises a polymer coating on one or both sides, for example a polyurethane coating, a polyester coating, or a polyolefin coating such as for example a polyethylene coating.

[0053] The use of facers that are a sheet of aluminum, optionally coated on one or both sides with a polymer, has the synergistic advantage of obtaining a more sustainable thermal insulation panel. The aluminum facer has a high density and does not interact with fluids, which is the case for facers comprising one or more layers of paper (the interaction of the paper with the fluid used in polyisocyanurate recycling significantly increases the viscosity and makes separation of the more difficult). After crushing the thermal insulation panel according to the invention, the aluminum can be separated easily from the aluminum sheets, either in dry form by using separation techniques based on differences in density of the material (e.g. wind sifting), or in a wet state by means of filtration. Facers comprising one or more layers of paper have a low density, making separation in a dry state by means of a density -based separation technique difficult.

[0054] The optional use of a coating on one or both sides of the aluminum facer can be beneficial to the sustainability of the thermal insulation panel.

[0055] Preferably, the aluminum sheet has a polyurethane coating on the side facing the polyisocyanurate foam.

[0056] Such a polyurethane coating on the aluminum sheet on the side facing the polyisocyanurate foam, has the advantage of obtaining good adhesion between the polyisocyanurate foam core and the aluminum sheet. Furthermore, in a glycolysis process for recycling the polyisocyanurate foam, the polyurethane of the polyurethane coating on the aluminum sheet can also be converted into polyol, which can be used in the production of new polyisocyanurate foam.

[0057] This also allows the aluminum from the aluminum sheet to be easily separated from the polyisocyanurate foam core, facilitating recycling. This contributes positively to the sustainability of the polyisocyanurate insulation panel.

[0058] Preferably, the aluminum sheet has a polyurethane coating or a polyester coating on the side facing away from the polyisocyanurate foam.

[0059] This is a coating that protects the aluminum sheet on the outer side of the thermal insulation panel. In a glycolysis process, a polyester or polyurethane coating can be converted into polyol together with the polyisocyanurate, and thus into a useful raw material for producing new polyisocyanurate foam. This further contributes to the sustainable nature of the thermal insulation panel. Preferably, the aluminum sheet has a thickness of at least 30 micrometers, and preferably of at least 40 micrometers. Preferably, the aluminum sheet is thinner than 60 micrometers. For example, the aluminum sheet can have a thickness of 50 micrometers.

[0060] Preferably, the facer on the outer side of the thermal insulation panel has a structured surface, for example a waffled surface.

[0061] Preferably, the thermal insulation panel has a thickness between 50 and 300 mm.

[0062] Preferably, the thermal insulation panel has a thermal conductivity, expressed by the lambda value measured according to EN 13165:2012, between 0.02 and 0.023 W / (m*K), and preferably lower than 0.022 W / (m*K).

[0063] One aspect of the invention relates to a flat roof, which is thermally insulated with a thermal insulation panel according to the invention.

[0064] An example of a foam formulation according to the invention was composed as follows:

[0065] 659 parts by weight of a polymeric methylene diphenyl diisocyanate with a NCO content of 30.9 g / 100 g (measured according to ASTM D5155-96A),

[0066] 235 parts by weight of a polyester polyol, with hydroxyl number (IOH) 240 mg KOH / gram, which is comprised of

[0067] o 68 weight percent of polyester polyol produced from biomass,

[0068] o 29 weight percent of polyester polyol produced from recycled polyethylene terephthalate, and

[0069] o 3 weight percent of emulsifier;

[0070] 11 parts by weight of catalyst,

[0071] 7 parts by weight of a combination of surfactants,

[0072] 35 parts by weight of tri ethyl phosphate (TEP) as flame retardant,

[0073] 48 parts by weight of cyclopentane, and

[0074] 3 parts by weight of water. Of the polyester polyol, 68 weight percent weight (according to ASTM D6866-22) is bio-based, and it comprises 29 weight percent (according to ISO 14021 :2016) of recycled raw materials.

[0075] The foam formulation has a isocyanate index of 340.

[0076] With this foam formulation, polyisocyanurate insulation panels were made in various thicknesses: 80, 120 and 160 mm.

[0077] A 50 micrometer thick aluminum foil was used as facer, coated with polyurethane on the foam side and polyester resin on the outer side. The polyurethane coating on the foam side ensures a good adhesion of the polyisocyanurate foam to the aluminum foil. The polyester resin on the outer side ensures protection of the aluminum foil.

[0078] When recycling the polyisocyanurate panel, both the polyurethane coating on the foam side of the facer and the polyester resin on the outer side can be converted by means of glycolysis into polyester polyol, which can be used in the production of polyisocyanurate foam.

[0079] The thermal insulation value (lambda) of the polyisocyanurate panels was 0.021 W / (m*K), measured according to EN 13165:2012. The compression strength (measure of rigidity) at 10% deformation, measured perpendicular to the panel according to EN 826, was higher than 150 kPa.

[0080] The present invention is by no means limited to the embodiments described hereinbefore, but different variants may be realized without departing from the scope of the invention.

Claims

Claims1.- A foam formulation for producing a rigid polyisocyanurate foam, wherein the formulation comprises:- a polyester polyol, wherein at least 85 weight percent of the polyester polyol is formed by sustainable polyester polyol;- a blowing agent, wherein the blowing agent comprises water and an additional blowing agent;- at least one surfactant;- a catalyst;- a flame-retardant additive;- a polyisocyanate, preferably a polymeric methylene diphenyl diisocyanate.2.- The foam formulation according to claim 1, characterized in that the sustainable polyester polyol is selected from polyester polyol produced from recycled polyester (preferably from recycled polyethylene terephthalate) or from polyester polyol produced from a bio-based raw material, for example from vegetable raw material, or from combinations thereof.3.- The foam formulation according to any of the preceding claims, characterized in that the sustainable polyester polyol is a combination of polyester polyol produced from recycled polyester and of polyester polyol produced from a bio-based raw material, for example from a vegetable raw material.4.- The foam formulation according to claim 3, characterized in that the sustainable polyester polyol comprises between 20 and 60 weight percent of polyester polyol produced from polyethylene terephthalate (PET), and between 40 and 80 weight percent of polyester polyol produced from bio-based raw material, for example from vegetable raw material.5.- The foam formulation according to any of the preceding claims, characterized in that at least 50 weight percent - and preferably at least 60 weight percent - of the raw material of the polyester polyol is comprised of bio-based raw material.6.- The foam formulation according to any of the preceding claims, characterized in that at least 20 weight percent - and preferably at least 25 weight percent - of the raw material of the polyester polyol is comprised of recycled polyester.7.- The foam formulation according to any of the preceding claims, characterized in that at least 90 weight percent - and preferably at least 95 weight percent - of the raw material of the polyester polyol is comprised of bio-based raw material and / or of recycled polyester.8.- The foam formulation according to any of the preceding claims, characterized in that more than 80 weight percent - and preferably at least 90 weight percent and more preferably at least 95 weight percent - of the raw material of the polyester polyol is comprised of recycled polyester or of bio-based raw material, or of a combination thereof.9.- The foam formulation according to any of the preceding claims, characterized in that the isocyanate index of the foam formulation is higher than 320 and lower than 400, preferably lower than 360.10.- The foam formulation according to any of the preceding claims, characterized in that the hydroxyl number of the polyester polyol is between 220 and 260 mg KOH / gram.11.- The foam formulation according to any of the preceding claims, characterized in that the polyester polyol has a functionality of at least 2, and preferably of less than 2.3.12.- The foam formulation according to any of the preceding claims, characterized in that the blowing agent comprises a pentane, wherein the pentane comprises at least 85 weight percent - and preferably at least 95 weight percent - of cyclopentane.13.- The foam formulation according to claim 12, characterized in that the blowing agent does not comprise isopentane.14.- The foam formulation according to any of the preceding claims, characterized in that the flame retardant contains or is comprised of triethyl phosphate (TEP), preferably wherein the flame retardant does not contain tris(2-chloropropyl) phosphate (TCPP).15.- A rigid polyisocyanurate foam, characterized in that the rigid polyisocyanurate foam is obtained with a foam formulation according to any of the preceding claims.16.- The rigid polyisocyanurate foam as in claim 15, characterized in that the rigid polyisocyanurate foam has a density between 28 and 35 kg / m3.17.- A thermal insulation panel, characterized in that the thermal insulation panel comprises a core from polyisocyanurate foam according to any of the claims 15 - 16, wherein the core is foamed between two facers, preferably between gas-tight facers.18.- The thermal insulation panel according to claim 17, characterized in that each of two facers is an aluminum sheet, optionally coated on one or both sides with a polymer, e.g. with polyurethane.19.- The thermal insulation panel according to claim 18, characterized in that the aluminum sheet has a thickness of at least 30 micrometers, and preferably of at least 40 micrometers.20.- The thermal insulation panel as in any of the preceding claims 17 - 19, characterized in that the insulation panel has a thickness between 50 mm and 300 mm.21.- The thermal insulation panel as in any of the preceding claims 17 - 20, characterized in that the insulation panel has a thermal conductivity, expressed by thelambda value, between 0.02 and 0.023 W / (m*K), and preferably lower than 0.022 W / (m*K).