Manufacturing process for thermoset polyester foams

Abstract

The present invention relates to a method for manufacturing thermosetting polyester foams obtained from a polyol ester and a polyacid. It also relates to a foam obtainable by such a method. Furthermore, it relates to a thermosetting expandable composition and its use in the manufacture of thermosetting polyester foams.

Description

Title of the invention: Process for manufacturing thermoset polyester foams

[0001] SUBJECT OF THE INVENTION

[0002] The present invention relates to a process for manufacturing thermoset polyester foams obtained from an ester polyol and a polyacid. It also relates to a foam obtainable by such a process. It further relates to a thermosetting expandable composition and its use for manufacturing thermoset polyester foams.

[0003] TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0004] It is known to prepare thermoset polyester foams by reacting a polyol and a polyacid.

[0005] In application WO2010 / 059925, a highly crosslinked polyester is obtained by two steps: the first step consists of forming an uncrosslinked prepolymer by reacting a polyol and a polyacid at a relatively low first temperature and the second step of crosslinking the prepolymer either at a second temperature higher than the first, or at a moderate temperature in the presence of a crosslinking agent or a polymerization (esterification) catalyst. The absence of the catalyst in the first step seems to be essential to be able to implement this two-step process.

[0006] Some cured polymers are described as foams. Their density is, however, relatively high. The use of physical or chemical foaming agents is envisaged.

[0007] International application WO2012 / 052385 describes an expanded polymer obtained by reacting glycerol and citric acid at a temperature between 80 and 130°C until the conversion rate is at least 90%, optionally in the presence of an esterification catalyst. When a conversion rate of at least 90%, preferably 98%, is reached, the reaction mixture is heated to a higher temperature, around 150°C. The first step at low temperature is intended to avoid decarboxylation of the citric acid as far as possible.

[0008] The process described in this document requires very long reaction times, ranging from several hours to several tens of hours. The polymerization is preferably carried out in non-stick molds, for example made of Teflon. The foams thus obtained have a density of between 200 and 850 g / L.

[0009] International application WO2013 / 121033 describes an improvement of this process where the polymerization of glycerol and citric acid is carried out at contacting a substrate with an outer layer comprising at least one metal, a metal oxide or a metal halide. This process provides foams having a more regular pore size than those prepared by the process described in WO 2012 / 052385. The claimed densities are between 50 and 850 g / liter.

[0010] International application WO2016 / 207517, in the name of the Applicant, discloses a process for manufacturing polyester foams by thermosetting, of an expandable and thermosetting composition containing a polyol component comprising at least one element chosen from glycerol, diglycerol and glycerol oligomers, a polyacid component comprising citric acid, a surfactant, and a catalyst. The foams obtained have a fine porosity and low densities, between 20 and 120 g / liter. The disadvantage of glycerol-based foams is that their thermal decomposition fumes contain acrolein, an irritant and toxic component by inhalation and ingestion.

[0011] International application WO2019 / 122669, in the name of the Applicant, discloses a process for manufacturing polyester foams by thermosetting, in which glycerol is replaced by C4-C6 hydrogenated sugars. The polyester foams obtained have an appearance, density and thermal and mechanical performance equivalent to those based on glycerol and citric acid described in application WO2016 / 207517 but the fumes, produced by thermal degradation at 350°C, contain a hundred times less acrolein.

[0012] The foams described in the prior art, formed from polyol and polyacid, however have the disadvantage of having low water resistance. Tests have in fact shown that these foams disintegrate after being immersed in water. This disadvantage constitutes a brake, in particular for the use of such foams for hydroponic cultivation but also for the insulation of buildings.

[0013] The present invention is based on the discovery that mixing an ester-polyol compound formed from a cyclic ester and a polyol with a polyacid made it possible to form a foam having improved water resistance, and thus to retain the structure of this foam after immersion in water. Summary of the invention

[0014] Thus, the present invention relates to a method for manufacturing a thermoset polyester foam, comprising the following successive steps:

[0015] (o) heating a mixture comprising a cyclic ester, a first polyol, and a reaction catalyst between said cyclic ester and said first polyol, at a temperature between 80°C and less than 160°C, to form an ester-polyol composition,

[0016] (a) incorporating the following components into the ester-polyol composition:

[0017] - optionally a second polyol,

[0018] - a polyacid component comprising a pore-forming polyacid,

[0019] - a reaction catalyst between said polyacid component, said ester-polyol, and the possible second polyol, and

[0020] - a surfactant composition, for forming a thermoset expandable composition cissable,

[0021] (b) heating the thermosetting expandable composition to a temperature at less than 160°C, preferably between 170°C and 230°C, more particularly between 180°C and 210°C, to form a thermoset polyester foam.

[0022] In certain embodiments, step a) is carried out at a temperature of between 80°C and less than 160°C, and preferably for a period of between 10 minutes and 4 hours, preferably between 20 minutes and 2 hours and in particular between 30 minutes and 90 minutes.

[0023] In certain embodiments, step a) comprises the following successive sub-steps:

[0024] (al) incorporation of the following components into the ester-polyol composition:

[0025] - optionally said second polyol,

[0026] - said polyacid component comprising a pore-forming polyacid, and

[0027] - said reaction catalyst between said polyacid component, said ester-polyol, and the possible second polyol,

[0028] to form a composition of oligomeric esters,

[0029] (a2) incorporation of said surfactant composition into the ester composition oligomers, to obtain a thermosetting expandable composition,

[0030] wherein steps a1) and a2) are preferably each carried out at a temperature of between 80°C and less than 160°C, each for a duration of between 10 minutes and 4 hours.

[0031] In certain embodiments, the heating in step o) is carried out for a period of between 10 minutes and 4 hours, preferably between 20 minutes and 2 hours and in particular between 30 minutes and 90 minutes.

[0032] In certain embodiments, the heating in step b) is carried out for a period of between 10 minutes and 5 hours, preferably between 20 minutes and 4 hours and in particular between 30 minutes and 3 hours.

[0033] In some embodiments, the cyclic ester is selected from glycolide, lactide, tetramethyl glycolide, γ-butyrolactone, γ-valerolactone, δ-valerolactone, ε-caprolactone, γ-nonalactone, δ-decalactone, γ-pentalactone, γ-dodecalactone, γ-pentalactone, 3-methyl-4-octanolide, 3-methyl-4-nonanolide and a mixture of two or more thereof.

[0034] In certain embodiments, said first polyol is:

[0035] - a diol, in particular an aliphatic diol, such as a C1-C12 alkane diol, or a diol aromatic,

[0036] - a tetraol, in particular an aliphatic tetraol such as pentaerythritol,

[0037] - a hydrogenated sugar, preferably a hydrogenated sugar of formula CnH2n+2On where n is worth 4, 5 or 6, or

[0038] - a mixture of two or more of these.

[0039] In certain embodiments, said second polyol, when present, is:

[0040] - a diol, such as an aliphatic diol, such as a C1-C12 alkane diol, preferably in C2-C6,

[0041] - a tetraol, in particular an aliphatic tetraol (such as pentaerythritol),

[0042] - a hydrogenated sugar, preferably a hydrogenated sugar of formula CnH2n+2On where n is worth 4, 5 or 6, or

[0043] - a mixture of two or more of these.

[0044] In certain embodiments, the pore-forming polyacid is selected from citric acid and α-hydroxylated dicarboxylic acids of formula (I) HOOC-(CHR4)m -CHOH-COOH where m is an integer ranging from 1 to 4, for example from 1 to 3, in particular 1 or 2, or even 1, and each R4 independently represents a hydrogen atom, a hydroxyl group (-OH) or an alkyl group, preferably a C 1 4 alkyl group.

[0045] preferably the pore-forming polyacid is citric acid, malic acid, or tartaric acid, better still the pore-forming polyacid is citric acid.

[0046] In some embodiments, the polyacid component further comprises a non-porogenic polyacid.

[0047] In some embodiments, the polyacid component comprises at least 50% by weight, preferably at least 65% by weight and in particular at least 80% by weight of pore-forming polyacid, based on the total weight of the polyacid component.

[0048] In some embodiments, the surfactant composition is a mixture of an anionic surfactant and a cationic surfactant, preferably a mixture of a dodecyl sulfate salt (eg SDS) and a tetradecyltrimethylammonium salt (eg TT AB) or cetyltrimethylammonium salt (eg CT AB).

[0049] In certain embodiments, the thermosetting expandable composition contains at most 20% by weight, more preferably at most 10% by weight and in particular at most 5% by weight of water.

[0050] In certain embodiments, the method of the invention further comprises introducing into the thermosetting expandable composition up to 30% by weight, preferably up to 20% by weight, in particular up to 10% by weight, based on the dry weight of the total expandable composition, of one or more mineral or organic fillers.

[0051] In certain embodiments, the method of the invention comprises, after step a) and before step b), the following step:

[0052] b') introduction of the thermosetting expandable composition obtained into a mold or application of the expandable and thermosetting composition on a support.

[0053] In certain embodiments, the method of the invention further comprises, during or after step a) and before step b), foaming the thermosetting expandable composition,

[0054] the foaming preferably being carried out by whipping, beating, mechanical stirring and / or gas injection.

[0055] In certain embodiments, the method of the invention further comprises a step of machining the thermoset polyester foam obtained in step b).

[0056] In certain embodiments, the mass content of cyclic ester, relative to the total weight of the cyclic ester and first polyol components, in step o) is between 50% and 90%, preferably between 60% and 80%.

[0057] It also relates to a foam which can be obtained by the process as defined in the present application.

[0058] Another subject of the present invention is a thermosetting expandable composition obtained by a process comprising steps o) and a) as defined in the present application.

[0059] Another object of the present invention is the use of a thermosetting expandable composition as defined in the present application, for the manufacture of thermoset polyester foams. FIGURES

[0060] [Fig.l] Foam according to the invention, prepared according to procedure a) before (left) and after (right) immersion in water.

[0061] [Fig.2] Foam according to the invention, prepared according to procedure b) before (left) and after (right) immersion in water.

[0062] [Fig.3] Foam according to the invention, prepared according to procedure c) before (left) and after (right) immersion in water.

[0063] [Fig.4] Comparative foam, prepared according to the method of the international application WO2019 / 122667 before (left) and after (right) immersion in water. DETAILED DESCRIPTION

[0064] The first step of the process according to the invention (step o)) is a step of forming an ester-polyol type compound. Said ester-polyol prepared in this step may be monomeric or oligomeric.

[0065] The reaction mixture comprising the cyclic ester, the first polyol, and the ca reaction catalyst between said cyclic ester and said first polyol, is typically prepared by physical mixing of the ingredients.

[0066] In a particular embodiment, said first polyol may be liquefied by heating, before adding the cyclic ester and then the reaction catalyst between said cyclic ester and said first polyol.

[0067] The mixture of step o) is essentially anhydrous. By "essentially anhydrous" (or "essentially water-free") is meant "containing at most 10% by weight of water, in particular at most 5% by weight of water, or even at most 2% by weight of water".

[0068] By "cyclic ester" is meant any cyclic organic compound, preferably alicyclic (i.e. cyclic aliphatic), comprising at least one (for example, one or two) ester function within its cycle. The cyclic ester preferably has 3 to 14 carbon atoms. The cyclic ester may in particular be chosen from glycolide, lactide, tetramethyl glycolide, γ-butyrolactone, γ-valerolactone, δ-valerolactone, ε-caprolactone, γ-nonalactone, δ-decalactone, γ-pentalactone, γ-dodecalactone, γ-pentalactone, 3-methyl-4-octanolide, 3-methyl-4-nonanolide, and a mixture of two or more of these. Preferably, the cyclic ester is lactide, γ-valerolactone, δ-valerolactone or ε-caprolactone, more preferably ε-caprolactone.

[0069] By "polyol" is meant any organic compound comprising at least 2 hydroxy functions, or a mixture of such compounds. The polyol may in particular be a diol, a triol (e.g. trimethylolpropane), a tetraol (e.g. pentaerythritol), a pentaol, a hexaol (e.g. dipentaerythritol) or a heptaol. The polyol may be aliphatic (linear or branched), alicyclic (i.e. mono- or polycyclic aliphatic), or aromatic.

[0070] In a particular embodiment, said first polyol is a diol.

[0071] In a more particular embodiment, the diol is an aliphatic diol (linear or branched), of preferably a C1-C12 alkane diol (preferably C2-C6), or an aromatic diol (preferably C6-C12).

[0072] Examples of Cl-Cl 2 alkanediols include methanediol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol.

[0073] Examples of C2-C6 alkanediol include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, and 1,6-hexanediol.

[0074] Examples of aromatic diols include 1,3-benzenedimethanol, 1,4-benzenedimethanol, and bis(2-hydroxyethyl)terephthalate.

[0075] In a particular embodiment, said first polyol is a tetraol, in particular an aliphatic tetraol, such as pentaerythritol.

[0076] In a more particular embodiment, said first polyol is a mixture of a diol (in particular an aliphatic or aromatic diol) and a tetraol (in particular an aliphatic tetraol, such as pentaerythritol).

[0077] In another particular embodiment, said first polyol is a hydrogenated sugar.

[0078] Hydrogenated sugars (also called "alditols" or "alcohols of sugars”), the hydrogenation products of carbohydrates (or “saccharide”, including monosaccharide, disaccharide, oligosaccharide or polysaccharide) where the aldehyde or ketone group has been reduced to the -OH function. The hydrogenation can be carried out by known methods operating under conditions of elevated hydrogen pressure and temperature, in the presence of a catalyst selected from elements of groups IB, IIB, IVB, VI, VII and VIII of the periodic table of elements, preferably from the group comprising nickel, platinum, palladium, cobalt, molybdenum and mixtures thereof. The preferred catalyst is Raney nickel.

[0079] The hydrogenated sugar is preferably chosen from hydrogenated sugars of formula CnH2n+2On where n is 4, 5 or 6, and the hydrogenation products of starch hydrolysates.

[0080] Better still, the hydrogenated sugar is a hydrogenated sugar of formula CnH2n+2On where n is 4, 5 or 6.

[0081] Starch hydrolysates are products obtained by enzymatic and / or acid hydrolysis of starch. The degree of hydrolysis is generally characterized by the dextrose equivalent (DE), defined by the following relationship:

[0082] [Chem.l] / œmbæ of \ DE=W0x | s. œmbæ of say glywadiqœs /

[0083] The preferred starch hydrolysates have, before the hydrogenation step, a DE of between 5 and 99, and advantageously between 10 and 80.

[0084] Examples of hydrogenated sugars of formula CnH2n+2On where n is 4, 5 or 6 include: erythritol (C4), treitol (C4), arabitol (C5), xylitol (C5), ribitol (C5), mannitol (C6), sorbitol (C6), galactitol (C6), fucitol (C6) or iditol (C6). Preferably, sorbitol, mannitol, xylitol and / or erythritol will be used.

[0085] Other examples of hydrogenated sugars are isomaltitol or maltitol.

[0086] Due to the toxicity of thermal degradation fumes, and in particular the release of acrolein, the thermosetting expandable composition preferably contains little or no glycerol, diglycerol and glycerol oligomers, that is, it contains less than 1% by weight, preferably less than 0.1% by weight of glycerol, diglycerol or glycerol oligomers, expressed relative to the total dry weight of the composition. The expandable composition is preferably free of glycerol, diglycerol and oligoglycerol.

[0087] Other examples of polyols include reducing or non-reducing sugars.

[0088] Reducing sugars are understood to mean carbohydrates of formula C„(H2O),, having at least one aldehyde or ketone group (reducing group). The reducing sugars which can be used in the present invention include oses (monosaccharides) and osides (disaccharides, oligosaccharides and polysaccharides).

[0089] Examples of monosaccharides that may be mentioned are those containing 4 to 8 carbon atoms, preferably aldoses and advantageously aldoses containing 5 to 7 carbon atoms. Particularly preferred aldoses are natural aldoses (belonging to the D series), in particular hexoses such as glucose, mannose and galactose. Lactose or maltose are examples of disaccharides that can be used as reducing sugars. Starch hydrolysates obtained by enzymatic hydrolysis or acid hydrolysis of starch may also be used. Non-reducing sugars that can be used are in particular sucrose and trehalose.

[0090] In certain embodiments, said first polyol comprises one or more hydrophobic groups, such as fatty chains or aromatic groups. The introduction of such hydrophobic groups makes it possible to increase the hydrophobic character of the foams and reduce their affinity for water.

[0091] In a more particular embodiment, said first polyol is a mixture of polyols comprising at least 50% by weight, preferably at least 60% by weight, more preferably at least 70%, and ideally at least 80% by weight of diol (based on the total weight of the mixture of polyols). In such an embodiment, the complement to 100% may for example be an aliphatic tetraol, such as pentaerythritol, and / or a hydrogenated sugar.

[0092] In an even more particular embodiment, said first polyol is a mixture of polyols comprising at least 50% by weight, preferably at least 60% by weight, more preferably at least 70%, and ideally at least 80% by weight of aliphatic diol (linear or branched), such as a C1-C12 (or even C2-C6) alkane diol, or aromatic diol (based on the total weight of the mixture of polyols). In such an embodiment, the remainder to 100% may for example be an aliphatic tetraol, such as pentaerythritol, and / or a hydrogenated sugar.

[0093] In a preferred embodiment, the first polyol is:

[0094] - a diol, such as an aliphatic diol (eg a C1-C12 alkane diol, preferably C2-C6) or an aromatic diol,

[0095] - a tetraol, in particular an aliphatic tetraol (such as pentaerythritol),

[0096] - a hydrogenated sugar, preferably a hydrogenated sugar of formula CnH2n+2On where n is worth 4, 5 or 6, or

[0097] - a mixture of two or more of these.

[0098] The mass content of cyclic ester, relative to the total weight of the cyclic ester and first polyol components, in step o) is advantageously between 50% and 90%, preferably between 60% and 80%.

[0099] The cyclic ester and said first polyol as defined above together preferably represent at least 70%, or even at least 80%, in particular at least 90% of the dry weight of the mixture of step o).

[0100] The catalyst used in step o) includes any compound capable of triggering or accelerating the esterification reaction (or "trans-esterification") between said first polyol and the cyclic ester, causing ring opening of the latter. In general, any type of esterification catalyst can be used.

[0101] Examples of esterification catalysts include strong acids, monocarboxylic acids, or salts thereof, such as:

[0102] - phosphorus catalysts, including in particular those chosen from the group consisting of alkali metal hypophosphite (H2PO2M, where M = alkali metal), alkali metal phosphite (HPO3M2, where M = alkali metal), alkali metal polyphosphate (M3PO4), alkali metal hydrogen phosphate (M2HPO4, where M = alkali metal), phosphoric acid (H3PO4), alkylphosphonic acid (RPO3H2, where R is alkyl) and a mixture of two or more of these compounds;

[0103] - hydrochloric acid, hydroiodic acid, hydrobromic acid, acid sulfuric acid, nitric acid, chloric acid, boric acid, perchloric acid, trifluoroacetic acid, a sulfonic acid (eg para-toluenesulfonic acid or trifluoromethanesulfonic acid),

[0104] - metal salts, including in particular zinc salts (eg zinc acetate, zinc chloride), titanium salts (eg titanium acetate, titanium chloride, titanium n-butoxide), manganese salts (eg manganese acetate), tin salts (eg tin octoate, tin oxalate), iron salts or zirconium salts.

[0105] Preferably, the catalyst used in step o) is a zinc salt.

[0106] The concentration of the reaction catalyst between said cyclic ester and said first polyol is typically between 0.1 and 10% by weight, preferably between 1 and 5% by weight, relative to the total weight of the cyclic ester, first polyol, and catalyst components.

[0107] The mixture formed in step o) is heated to a temperature of between 80°C and less than 160°C, for example between 80°C and 140°C, preferably between 95°C and 135°C (for example, between 95°C and 110°C or between 120°C and 135°C). Heating at step o) is preferably carried out for a period of between 10 minutes and 4 hours, preferably between 20 minutes and 2 hours, in particular between 30 minutes and 90 minutes. An ester-polyol composition is thus obtained at the end of step o).

[0108] Preferably, the heating in step o) is carried out with mechanical stirring.

[0109] During step a), the ester-polyol composition obtained in step o) is mixed with the following components:

[0110] - optionally a second polyol,

[0111] - a polyacid component comprising a pore-forming polyacid,

[0112] - a reaction catalyst between said polyacid component, said ester-polyol, and the possible second polyol, and

[0113] - a surfactant composition.

[0114] In the present application, the quantities or contents of polyol or polyacid components are always understood to refer to all the polyols or all the polyacids present in the composition. In particular, when a compound, present in the thermosetting expandable composition, can be considered both as a first of the four (or five if the second polyol is present) components and as a second of the four (or five) components of the composition (ester polyol, the possible second polyol, polyacid component, surfactant, catalyst) it will be considered both as one and the other. This implies that it will be taken into account in the quantities of each of these two components.

[0115] In a particular embodiment, the aforementioned components are added to the ester-polyol composition, and the resulting mixture is heated to a temperature of between 80°C and less than 160°C (for example between 100°C and 140°C, or even between 110°C and 135°C), and preferably for a time of between 10 minutes and 4 hours, preferably between 20 minutes and 2 hours and in particular between 30 minutes and 90 minutes.

[0116] The temperature in step a) may be greater than or equal to, preferably greater than, the heating temperature in step o).

[0117] Preferably, the heating in step a) is carried out with mechanical stirring.

[0118] In a preferred embodiment, step a) comprises the following successive sub-steps:

[0119] (al) incorporation of the following components into the ester-polyol composition:

[0120] - optionally said second polyol,

[0121] - said polyacid component comprising a pore-forming polyacid, and

[0122] - said reaction catalyst between said polyacid component, said ester-polyol, and the possible second polyol,

[0123] to form an oligomeric ester composition, and

[0124] (a2) incorporation of said surfactant composition into the ester composition oligomers, to obtain a thermosetting expandable composition,

[0125] Steps a1) and a2) are preferably each carried out at a temperature of between 80°C and less than 160°C (for example between 100°C and 140°C, or even between 110°C and 135°C. In a particular embodiment, the temperature in step a1) and the temperature in step a2) are identical to each other, and are identical to the heating temperature of step o). In a preferred embodiment, the temperature in step a1) and the temperature in step a2), of between 80°C and less than 160°C (for example between 100°C and 140°C, or even between 110°C and 135°C), are identical to each other, and are higher than the heating temperature of step o).

[0126] Generally speaking, it is preferred that the heating temperatures in step o), a1), a2), denoted respectively To, Tal and Ta2 below, are each between 80°C and less than 160°C (for example between 100°C and 140°C, or even between 110°C and 135°C), and comply with the following rule: To < Tal < Ta2, better still To < Tal < Ta2.

[0127] Steps a1) and a2) are preferably each carried out for a duration of between 10 minutes and 4 hours, for example between 20 minutes and 2 hours, in particular between 30 minutes and 90 minutes.

[0128] Preferably, the heating in steps a1) and a2) is carried out with mechanical stirring.

[0129] When present, said second polyol is chosen from the polyols defined above for said first polyol. The particular and preferred embodiments described for the first polyol apply to the second polyol.

[0130] Said first polyol and said second polyol may be the same or different.

[0131] In a particular embodiment, the components of step a) (or al) do not comprise a second polyol.

[0132] In another particular embodiment, said second polyol (if present) is a mixture of polyols comprising at least 50% by weight, preferably at least 60% by weight, more preferably at least 70%, and ideally at least 80% by weight of diol (based on the total weight of the mixture of polyols). In such an embodiment, the remainder to 100% may for example be an aliphatic tetraol, such as pentaerythritol, and / or a hydrogenated sugar.

[0133] In a more particular embodiment, said second polyol (if present) is a mixture of polyols comprising at least 50% by weight, preferably at least 60% by weight, more preferably at least 70%, and ideally at least 80% by weight of aliphatic diol (linear or branched), better still of a C1-C12 (or even C2-C6) alkane diol (based on the total weight of the mixture of polyols). In such an embodiment, the remainder to 100% may for example be an aliphatic tetraol, such as pentaerythritol, and / or a hydrogenated sugar.

[0134] In a preferred embodiment, the second polyol is:

[0135] - a diol, such as an aliphatic diol, such as a C1-C12 alkane diol, preferably in C2-C6,

[0136] - a tetraol, in particular an aliphatic tetraol (such as pentaerythritol),

[0137] - a hydrogenated sugar, preferably a hydrogenated sugar of formula CnH2n+2On where n is worth 4, 5 or 6, or

[0138] - a mixture of two or more of these.

[0139] Better still, said second polyol is an aliphatic diol (linear or branched), or even a Cl-Cl 2 (or even C2-C6) alkane diol.

[0140] The poly(carboxylic) acid component comprises at least one pore-forming polyacid. This pore-forming polyacid is an acid which comprises at least two carboxyl functions and which, under the thermosetting conditions of the foam, degrades and releases a gaseous component (generally CO2) which allows the expansion of the composition and the formation of the foam.

[0141] The pore-forming polyacid is particularly chosen from citric acid and the α-hydroxylated dicarboxylic acids of formula (I) HOOC-(CHR4)m-CHOH-COOH where m is an integer ranging from 1 to 4, for example from 1 to 3, in particular 1 or 2, or even 1, and each R4 independently represents a hydrogen atom, a hydroxyl group (-OH) or an alkyl group, preferably a C1-4 alkyl group,

[0142] Preferably, the pore-forming polyacid is citric acid, malic acid, or tartaric acid, more preferably the pore-forming polyacid is citric acid.

[0143] The polyacid component preferably comprises at least 50% by weight, or even at least 65% by weight, or even at least 80% by weight of pore-forming polyacid (based on the total weight of the polyacid component).

[0144] Other polyacids, i.e., non-porogenic polyacids, capable of reacting with the ester polyol and / or the second polyol (if present), to form a polyester network may be present. These other polyacids are preferably monomeric polyacids, i.e., polyacids which are not formed by polymerization of monomeric units bearing acid groups such as poly(acrylic acid).

[0145] Low molecular weight oligomeric polyacids, such as poly(maleic acid), can however be used without problem.

[0146] The other polyacids are preferably polycarboxylic acids, for example dicarboxylic, tricarboxylic or tetracarboxylic acids.

[0147] Dicarboxylic acids include, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, malic acid, tartaric acid, tartronic acid, aspartic acid, glutamic acid, fumaric acid, itaconic acid, maleic acid, traumatic acid, camphoric acid, acid phthalic acid and its derivatives, in particular containing at least one boron or chlorine atom, tetrahydrophthalic acid and its derivatives, in particular containing at least one chlorine atom such as chlorendic acid, isophthalic acid, terephthalic acid, mesaconic acid and citraconic acid. Dicarboxylic acids also include the corresponding anhydrides.

[0148] Tricarboxylic acids include, for example, tricarballylic acid, 1,2,4-butanetricarboxylic acid, aconitic acid, hemimellitic acid, trimellitic acid and trimesic acid.

[0149] Examples of tetracarboxylic acids that may be mentioned are 1,2,3,4-butanetetracarboxylic acid and pyromellitic acid.

[0150] The ester-polyol, second polyol (if present) and polyacid components as defined above represent, together, at least 70%, preferably at least 80% and in particular at least 90% of the dry weight of the expandable and thermosetting composition.

[0151] The ester-polyol component preferably represents from 5 to 55% by weight, in particular from 10 to 25% by weight, and ideally from 15 to 20% by weight of the total weight of the ester-polyol, second polyol (if present) and polyacid components.

[0152] The second polyol preferably represents from 0 to 40% by weight, in particular from 10 to 40% by weight and ideally from 15 to 35% by weight of the total weight of the ester-polyol, second polyol (if present) and polyacid components.

[0153] The polyacid component preferably represents from 20 to 70% by weight, in particular from 25 to 65% by weight, and ideally from 40 to 60% by weight of the total weight of the ester-polyol, second polyol (if present) and polyacid components.

[0154] In a known manner, the respective quantities of the ester-polyol, second polyol (if present) and polyacid components will be adjusted so that the -OH functions and the -COOH functions are present in a -OH / -COOH molar ratio of between 0.60 and 1.2, preferably between 0.70 and 1.1, in particular between 0.8 and 1.0.

[0155] Said catalyst used in step a) includes any compound capable of triggering or accelerating the esterification reaction between the hydroxyl functions of the ester-polyol compound (and / or said second polyol if present) and the carboxyl functions of the polyacid. In general, any type of esterification catalyst, as defined above, can be used. Preferably, the catalyst of step a) is chosen from phosphorus-containing catalysts, including in particular alkali metal hypophosphite (H2PO2M, where M = alkali metal), alkali metal phosphite (HPO3M2, where M = alkali metal), alkali metal polyphosphate (M3PO4, where M = alkali metal), alkali metal hydrogen phosphate (M2HPO4, where M = alkali metal), phosphoric acid (H3PO4), alkylphosphonic acid (RPO3H2, where R is an alkyl), or a mixture of two or more of these compounds. Better still, the catalyst for step a) is a metal hypophosphite alkaline.

[0156] The concentration of the reaction catalyst in step a) (or al)) is typically between 0.1 and 10% by weight, preferably between 1 and 7% by weight, or even between 2 and 5%, relative to the total dry weight of the expandable composition.

[0157] The surfactant composition consists of one or more surfactants, preferably one or more ionic (i.e. anionic, cationic, amphoteric) surfactants. The surfactant composition added in step a) (or a2)) has the function of improving the quality of the foam, i.e. reducing the pore size, narrowing the pore size distribution and reducing the density of the cured foams obtained.

[0158] In a preferred embodiment, the surfactant composition is a mixture of an anionic surfactant and a cationic surfactant. A combination of two types of surfactants with opposite charges makes it possible to stabilize the surfactant film at the water / air interface by reducing the repulsion between molecules of the same charge. Examples of such combinations include a mixture of an anionic surfactant chosen from dodecyl sulfate salts (e.g. sodium dodecyl sulfate, also denoted SDS) and a cationic surfactant chosen from tetradecyltrimethyl ammonium salts (e.g. tetradecyltrimethyl ammonium bromide, also denoted TT AB) and cetrimonium salts (e.g. cetrimonium bromide, also denoted CT AB). The use of a combination of these two types of surfactants therefore constitutes a preferred embodiment.The weight ratio of cationic surfactant to anionic surfactant is preferably between 1.5 and 2.5, in particular between 1.8 and 2.2 and ideally close to 2.

[0159] In another embodiment, the surfactant composition comprises an amphoteric surfactant, optionally in admixture with an anionic surfactant. The amphoteric surfactant typically comprises a positive charge on at least one nitrogen atom (e.g., a quaternary ammonium group) and a negative charge on at least one oxygen atom (e.g., in a group selected from an amine oxide, carboxylate, sulfate, sulfonate, phosphate, and phosphonate). More particularly, the amphoteric surfactant may comprise at least one linear C8-C20 alkyl chain, at least one positively charged nitrogen atom (e.g., in a quaternary ammonium group), and at least one negatively charged oxygen (e.g., in a group selected from an amine oxide, carboxylate, sulfate, sulfonate, phosphate, or phosphonate). Examples of amphoteric surfactants include:

[0160] - alkylbetaines of formula II: R1R2R3N+-CH2-C(O)2

[0161] - alkylsulfobetaines of formula III: R1R2R3N+-CH2-CH2-CH2-S(O)3

[0162] - alkylhydroxysultaines of formula IV: R1R2R3N+-CH2-C(OH)H-CH2-S(O)3

[0163] - amine oxides of formula V: R*R2R3N+-O

[0164] - alkylamidobetaines of formula VI: R1-CO-NH-CH2-CH2-CH2-R2R3N+-CH2-C(O)2

[0165] where in formulas II, III, IV, V and VI, R1 is an aliphatic chain having from 8 to 20 carbon atoms and, R2 and R3 are each an aliphatic chain having from 1 to 4 carbon atoms.

[0166] Other examples of amphoteric surfactants include acylphosphocholines, phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols and lecithin.

[0167] More specific examples of amphoteric surfactants include cocamidopropyl betaine, cocamidopropyl hydroxysultaine, coco-betaine, sodium lauroam-phoacetate, lauryl sulfobetaine, lauryl hydroxysultaine and a lecithin (e.g. soy lecithin).

[0168] The amphoteric surfactant may also be a polymeric amphoteric surfactant, preferably chosen from amphiphilic polymers, micellar polymers, hydrophobically modified water-soluble polymers or associative polymers.

[0169] Examples of anionic surfactants, which may in particular be combined with an amphoteric surfactant, are in particular those chosen from the group of C8-C18 alkyl sulfate salts, C8-C18 alkyl ether sulfate salts, C8-C18 alkyl carboxylate salts, C8-C18 alkyl ether carboxylate salts (e.g. sodium or potassium laureth-4-carboxylate), C8-C18 alkyl sulfonate salts, C8-C18 alkyl ether sulfonate salts, C8-C18 alkyl succinate salts, and C8-C18 alkyl ether succinate salts.

[0170] The weight ratio of amphoteric surfactant to anionic surfactant is advantageously in the range from 5:1 to 1:5, in particular in the range from 3:1 to 1:3.

[0171] Preferably, the surfactant composition does not comprise alkylpolyglycosides, or even generally non-ionic surfactant.

[0172] The amount of surfactant(s) advantageously represents from 0.1 to 10%, preferably from 1 to 8%, and in particular from 2 to 6% of the total dry weight of the expandable composition.

[0173] Although the presence of water during step (a) (or al), or a2)) may be advantageous for reasons of ease of implementation of the thermosetting expandable composition, care will be taken to limit this quantity of water as much as possible. Indeed, the esterification and decomposition reactions of porogenic polyacid which result in the formation of a thermoset polyester foam can only take place after complete evaporation of the water, which necessarily requires an input of additional thermal energy. Consequently, the thermosetting expandable composition curable preferably contains at most 20% by weight, more preferably at most 10% by weight, and in particular at most 5% by weight of water.

[0174] The thermosetting expandable composition may further contain up to 30% by weight, preferably up to 20% by weight, in particular up to 10% by weight, based on the dry weight of the total expandable composition, of one or more mineral or organic fillers.

[0175] Finally, the expandable composition may contain one or more other additives conventionally used in the polymer processing and transformation industry such as dyes, pigments, antibacterial or antifungal agents, flame retardants, UV absorbers, hydrophobic agents. These additives preferably represent in total at most 10% of the dry weight of the expandable composition.

[0176] Although the expandable composition may, in principle, contain a blowing agent other than the pore-forming polyacid (in particular a physical blowing agent), it is important to note that it is not necessary to add one. Indeed, the pore-forming polyacid, present in the polyacid component, acts as a blowing agent. When the expandable composition is heated, in step (b), the pore-forming polyacid decomposes and generates CO2 (MM Barbooti et al. “Thermal Decomposition of Citric Acid”, Thermochimica Acta, 98 (1986), 119-126; D. Wyr-zykowski et al. “Thermal Behavior of Citric Acid and Isomeric Aconitic Acids”, J. Therm. Anal. Calorim. (2001), 104:731-735).In a preferred embodiment of the method of the present invention, the expandable composition is therefore essentially free (typically less than 5% by weight, or even less than 2% by weight, or even less than 1% by weight relative to the dry weight of the expandable composition) or even totally free of expansion agent other than the pore-forming polyacid (in particular essentially free of physical expansion agent).

[0177] In a preferred embodiment, the method according to the invention comprises, after step a) and before step b), a step b') of introducing the thermosetting expandable composition obtained into a mold or applying the expandable and thermosetting composition to a support.

[0178] In an advantageous embodiment, the method for manufacturing thermoset polyester foams of the present invention comprises, during or after step a) and before step b) (and b') if implemented), foaming the thermosetting expandable composition. This foaming, i.e. the incorporation of air or another gas into the liquid thermosetting expandable composition, makes it possible to increase the volume of the thermosetting expandable composition, to reduce the density of the final foams and to homogenize the distribution of pore sizes in the final foams. The foaming can be carried out by mechanical means, for example by whipping, beating or mechanical stirring and / or by injection of gas.

[0179] When the hot thermosetting expandable composition is spread in the form of a continuous film on a support, the thickness of the film, before heating, i.e. before expansion and hardening, is advantageously at least equal to 1 mm, preferably at least equal to 2 mm, in particular at least equal to 5 mm, and more preferably at least equal to 10 mm. The surface mass of the film, before heating, i.e. before expansion and hardening, is advantageously between 1 and 20 kg / m2, preferably between 1.5 and 5 kg / m2.

[0180] Step b) of the method of the invention comprises heating the thermosetting expandable composition. The heating temperature is typically a temperature close to the decomposition temperature of the pore-forming polyacid. The heating temperature in step b) is at least 160°C, or even at least 165°C, preferably between 170°C and 230°C, more particularly between 180°C and 210°C.

[0181] To heat the expandable composition in step b), it is possible in principle to use any usual means known in the field of the processing and transformation of polymers, such as hot air, thermal radiation, microwaves or contact with a hot support (mold).

[0182] The duration of heating in step b) depends not only on the temperature, but also on the heating means and the volume / surface ratio of the foam block formed. The duration of heating in step b) is preferably between 10 minutes and 5 hours, for example between 20 minutes and 4 hours, and in particular between 30 minutes and 3 hours.

[0183] Preferably, the heating in step b) is carried out in the absence of stirring.

[0184] In a preferred embodiment, the method according to the invention further comprises a step of machining the thermoset polyester foam obtained in step b).

[0185] The volume of the formed foam block can vary between very wide limits. When the expandable composition is used in a continuous process forming, for example, strips or profiles of insulating materials, it is potentially infinite. When the expandable composition is used to form discrete blocks, for example foam plates or sheets, its quantity is preferably such that the volume of each block of solid thermoset foam is at least equal to 500 cm3, preferably at least equal to 0.001 m3, in particular at least equal to 0.01 m3. The foam block is preferably in the form of a plate.

[0186] Another object of the present invention is a foam obtainable by the process as defined in the present application.

[0187] It is understood that the different aspects, particular and preferred embodiments, described above for the method of the invention apply to the foam which can be obtained by such a process.

[0188] The present application also relates to a thermosetting expandable composition (typically solid at room temperature (in particular at a temperature of 25°C) and essentially free of water) obtained by a process comprising steps o) and a), preferably steps o), a1) and a2) as defined above.

[0189] It is understood that the different aspects, particular and preferred embodiments, described above for steps o), a), a1), a2) (components, conditions, etc.) of the process of the invention apply to the thermosetting expandable composition as such.

[0190] The present invention further relates to the use of such a thermosetting expandable composition for the manufacture of thermoset polyester foams. EXAMPLES

[0191] Example 1. Synthesis of thermoset foams according to the invention

[0192] a) 8.79 g of e-caprolactone, 2.50 g of 1,3-propanediol, 0.39 g of pentaerythritol and 0.34 g of zinc acetate dihydrate were placed in a flask. The mixture was heated to 100°C with moderate stirring for 1 hour. 5.90 g of 1,3-propanediol, 19.13 g of citric acid and 1.95 g of sodium hypophosphite were then added to the flask. The resulting mixture was then heated to 125°C with moderate stirring for 1 hour.

[0193] 1.30 g of cetyltrimethylammonium bromide (CTAB) and 0.65 g of lauryl sulfate sodium (SDS), were finally added to the flask. The resulting mixture was maintained at 125°C and mixed with vigorous stirring for 1 hour. The final mixture was poured into a 10 cm x 10 cm mold and placed in an oven heated to 200°C for at least 2 hours.

[0194] b) 18.04 g of e-caprolactone, 5.12 g of 1,3-propanediol, 0.80 g of pentaerythritol and 0.69 g of zinc acetate dihydrate were placed in a flask. The mixture was heated to 100°C with moderate stirring for 1 hour. 13.02 g of citric acid and 1.32 g of sodium hypophosphite were then added to the flask. The resulting mixture was then heated to 125°C with moderate stirring for 1 hour.

[0195] 1.30 g of cetyltrimethylammonium bromide (CTAB) and 0.65 g of lauryl sulfate sodium (SDS), were finally added to the flask. The resulting mixture was maintained at 125°C and mixed with vigorous stirring for 1 hour. The final mixture was poured into a 10 cm x 10 cm mold and placed in an oven heated to 200°C for at least 2 hours.

[0196] c) 16.29 g of e-caprolactone, 8.40 g of 1,4-benzenedimethanol, 0.72 g of pentaerythritol and 0.63 g of zinc acetate dihydrate were placed in a flask. The mixture was heated to 100°C with moderate stirring for 1 hour. 11.76 g of citric acid and 1.20 g of sodium hypophosphite were then added to the flask. The resulting mixture was then heated to 125°C with moderate stirring for 1 hour.

[0197] 1.30 g of cetyltrimethylammonium bromide (CTAB) and 0.65 g of lauryl sulfate sodium (SDS), were finally added to the flask. The resulting mixture was maintained at 125°C and mixed with vigorous stirring for 1 hour. The final mixture was poured into a 10 cm x 10 cm mold and placed in an oven heated to 200°C for at least 2 hours.

[0198] The foam prepared according to procedure a) above was immersed in a volume of water for 5 min. [Fig.l] demonstrates that the foam, subjected to manual compression, after immersion, retains its structure and does not disintegrate.

[0199] The same experiment was carried out with the foam prepared according to procedure b) ([Fig.2]) and c) ([Fig.3]). Here again, the foams, subjected to manual compression after immersion in water, retain their structure and do not disintegrate.

[0200] As a comparative example, a foam prepared according to the method of application WO2019 / 122667 was immersed in a volume of water for 5 min. [Fig.4] shows that the foam, subjected to manual compression, disintegrated after immersion in water.

[0201] [Tables 1] Foam Water resistance a) + b) ++ c) ++ Comparison -

[0202] ++> + »-

[0203] “-”: disintegration after immersion in water

[0204] “++”, “+”: no disintegration after immersion in water

Claims

Claims

1. A method of manufacturing a thermoset polyester foam, comprising the following successive steps: (o) heating a mixture comprising a cyclic ester, a first polyol, and a reaction catalyst between said cyclic ester and said first polyol, to a temperature of between 80°C and less than 160°C, to form an ester-polyol composition, (a) incorporating the following components into the ester-polyol composition: - optionally a second polyol, - a polyacid component comprising a pore-forming polyacid, - a reaction catalyst between said polyacid component, said ester-polyol, and the optional second polyol, and - a surfactant composition, to form a thermoset foamable composition, (b) heating the thermoset foamable composition to a temperature at least equal to 160°C, preferably between 170°C and 230°C, more particularly between 18 ... °C and 210 °C,to form a thermoset polyester foam.,

2. Method according to claim 1, characterized in that step a) is carried out at a temperature between 80°C and less than 160°C, and preferably for a duration between 10 minutes and 4 hours, preferably between 20 minutes and 2 hours and in particular between 30 minutes and 90 minutes.

3. A method according to claim 1, wherein step a) comprises the following successive sub-steps: (a1) incorporating the following components into the ester-polyol composition: - optionally said second polyol, - said polyacid component comprising a pore-forming polyacid, and - said reaction catalyst between said polyacid component, said ester-polyol, and the optional second polyol, to form an oligomeric ester composition, (a2) incorporating said surfactant composition into the oligomeric ester composition, to obtain a thermoset expandable composition, wherein steps a1) and a2) are preferably each carried out at a temperature of at least 100°C. temperature between 80°C and less than 160°C, each for a duration of between 10 minutes and 4 hours.

4. Method according to any one of the preceding claims, characterized in that the heating in step o) is carried out for a period of between 10 minutes and 4 hours, preferably between 20 minutes and 2 hours and in particular between 30 minutes and 90 minutes.

5. Method according to any one of the preceding claims, characterized in that the heating in step b) is carried out for a period of between 10 minutes and 5 hours, preferably between 20 minutes and 4 hours and in particular between 30 minutes and 3 hours.

6. A method according to any one of the preceding claims, characterized in that the cyclic ester is chosen from glycolide, lactide, tetramethyl glycolide, γ-butyrolactone, γ-valerolactone, δ-valerolactone, ε-caprolactone, γ-nonalactone, δ-decalactone, γ-pentalactone, γ-dodecalactone, γ-pentalactone, 3-methyl-4-octanolide, 3-methyl-4-nonanolide and a mixture of two or more of these.

7. Process according to any one of the preceding claims, characterized in that said first polyol is: - a diol, in particular an aliphatic diol, such as a Cl-Cl2 alkane diol, or an aromatic diol, - a tetraol, in particular an aliphatic tetraol such as pentaerythritol, - a hydrogenated sugar, preferably a hydrogenated sugar of formula CnH 2n+2On where n is 4, 5 or 6, or - a mixture of two or more of these.

8. Process according to any one of the preceding claims, characterized in that said second polyol, when present, is: - a diol, such as an aliphatic diol, such as a C1-C12, preferably C2-C6, alkane diol, - a tetraol, in particular an aliphatic tetraol (such as pentaerythritol), - a hydrogenated sugar, preferably a hydrogenated sugar of formula CnH 2n+2On where n is 4, 5 or 6, or - a mixture of two or more of these.

9. Method according to any one of the preceding claims, characterized in that the pore-forming polyacid is chosen from acid citric acid and α-hydroxylated dicarboxylic acids of formula (I) HOOC-(CHR4)m-CHOH-COOH where m is an integer ranging from 1 to 4, for example from 1 to 3, in particular 1 or 2, or even 1, and each R4 independently represents a hydrogen atom, a hydroxyl group (-OH) or an alkyl group, preferably a C, 4 alkyl group. preferably the pore-forming polyacid is citric acid, malic acid, or tartaric acid, more preferably the pore-forming polyacid is citric acid.

10. A method according to any one of the preceding claims, characterized in that the polyacid component further comprises a non-porogenic polyacid.

11. Method according to any one of the preceding claims, characterized in that the polyacid component comprises at least 50% by weight, preferably at least 65% by weight and in particular at least 80% by weight of pore-forming polyacid, relative to the total weight of the polyacid component.

12. Method according to any one of the preceding claims, characterized in that the surfactant composition is a mixture of an anionic surfactant and a cationic surfactant, preferably a mixture of a dodecyl sulfate salt and a tetradecyltrimethylammonium or cetyltrimethylammonium salt.

13. Method according to any one of the preceding claims, characterized in that the thermosetting expandable composition contains at most 20% by weight, more preferably at most 10% by weight and in particular at most 5% by weight of water.

14. Method according to any one of the preceding claims, characterized in that it further comprises the introduction into the thermosetting expandable composition of up to 30% by weight, preferably up to 20% by weight, in particular up to 10% by weight, based on the dry weight of the total expandable composition, of one or more mineral or organic fillers.

15. Process according to any one of the preceding claims, characterized in that the mass content of cyclic ester, relative to the total weight of the cyclic ester and first polyol components, in step o) is between 50% and 90%, preferably between 60% and 80%.

16. Foam obtainable by the process as defined in any one of claims 1 to 15.

17. Thermosetting expandable composition obtained by a process comprising steps o) and a) as defined in any one of claims 1-4, 6-15.

18. Use of a thermosetting expandable composition as defined in claim 17, for the manufacture of thermoset polyester foams.

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