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EP-4739734-A1 - PROCESS FOR THE MANUFACTURE OF THERMOSET POLYESTER FOAMS

EP4739734A1EP 4739734 A1EP4739734 A1EP 4739734A1EP-4739734-A1

Abstract

The present invention relates to a process for manufacturing thermoset polyester foams obtained from an ester polyol and a polyacid. The invention also relates to a foam that can be obtained by a process of said type. The invention further relates to a thermosetting expandable composition and to the use thereof for the manufacture of thermoset polyester foams.

Inventors

  • SOISSON, Arnaud
  • LEMAIRE, Marjorie

Assignees

  • Saint-Gobain Isover

Dates

Publication Date
20260513
Application Date
20240702

Claims (20)

  1. 1. Process for 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, at 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: - possibly 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 thermosetting expandable composition, (b) heating the thermosetting expandable composition to a temperature at least equal to 160°C, preferably between 170°C and 230°C, more particularly between 180°C and 210°C, to form a thermoset polyester foam.
  2. 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. 3. Method according to claim 1, in which step a) comprises the following successive sub-steps: (a1) incorporation of 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 a composition of oligomeric esters, (a2) incorporating said surfactant composition into the oligomeric ester composition, to obtain a thermosetting expandable composition, 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.
  4. 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. 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. 6. Process according to any one of the preceding claims, characterized in that the cyclic ester is chosen from glycolide, lactide, tetramethyl glycolide, y-butyrolactone, y-valerolactone, 5-valerolactone, s-caprolactone, y-nonalactone, 5-decalactone, YP enta lactone , y-dodecalactone, y-pentalactone, 3-methyl-4-octanolide, 3-methyl-4-nonanolide and a mixture of two or more of these.
  7. 7. Method 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 C1-C12 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 CnH2n+20n where n is 4, 5 or 6, or - a mixture of two or more of these.
  8. 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, alkanediol, - a tetraol, especially an aliphatic tetraol (such as pentaerythritol), - a hydrogenated sugar, preferably a hydrogenated sugar of formula CnH2n+20n where n is 4, 5 or 6, or - a mixture of two or more of these.
  9. 9. Process according to any one of the preceding claims, characterized in that the pore-forming polyacid is chosen from citric acid and the α-hydroxylated dicarboxylic acids of formula (I) HOOC-(CHR 4 ) 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 R 4 independently represents a hydrogen atom, a hydroxyl group (-OH) or an alkyl group, preferably a C 1-4 alkyl group, preferably the pore-forming polyacid is citric acid, malic acid, or tartaric acid, better still the pore-forming polyacid is citric acid.
  10. 10. Method according to any one of the preceding claims, characterized in that the polyacid component further comprises a non-porogenic polyacid.
  11. 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 porogenic polyacid, relative to the total weight of the polyacid component.
  12. 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. 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. 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, relative to the dry weight of the total expandable composition, of one or more mineral or organic fillers.
  15. 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. 16. Process according to any one of the preceding claims, characterized in that said cyclic ester, said first polyol, and said reaction catalyst between said cyclic ester and said first polyol together represent at least 90% by weight, or even at least 95% by weight, or even at least 98% by weight, for example at least 99% by weight, relative to the total weight of the mixture of step o).
  17. 17. Process according to any one of the preceding claims, characterized in that the mixture of step o) does not comprise polycarboxylic acid.
  18. 18. Foam obtainable by the process as defined in any one of claims 1 to 17.
  19. 19. Thermosetting expandable composition obtained by a process comprising steps o) and a) as defined in any one of claims 1-4, 6-17.
  20. 20. Use of a thermosetting expandable composition as defined in claim 19, for the manufacture of thermoset polyester foams.

Description

Manufacturing process for thermoset polyester foams SUBJECT OF THE INVENTION 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. TECHNOLOGICAL BACKGROUND OF THE INVENTION It is known to prepare thermoset polyester foams by reacting a polyol and a polyacid. In application WO2010/059925, a highly crosslinked polyester is obtained in two steps: the first step consists in forming a non-crosslinked prepolymer by reacting a polyol and a polyacid at a relatively low first temperature and the second step in 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 catalyst (esterification). The absence of the catalyst in the first step appears to be essential in order to be able to implement this two-step process. Some cured polymers are described as foams. Their density is, however, relatively high. The use of physical or chemical foaming agents is envisaged. International application WO2012/052385 describes an expanded polymer obtained by reacting glycerol and citric acid at a temperature of 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 low-temperature step is intended to avoid decarboxylation of the citric acid as far as possible. 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. International application WO2013/121033 describes an improvement of this process where the polymerization of glycerol and citric acid is carried out in contact with a substrate with an external 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. 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 selected 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. 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 performances 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. 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. 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 allows a foam to be formed having improved water resistance, and thus the structure of this foam to be retained after immersion in water. SUMMARY OF THE INVENTION Thus, the present invention relates to 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, at 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: - possibly 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 thermosetting expandable composition, (b) heating the thermo