USE OF EPOXY COMPOUNDS AS CARBON DIOXIDE SCAVENGERS IN PIR COMPRISING FOAMS FOR SUPERIOR THERMAL INSULATION PROPERTIES

Abstract

A reactive composition for making a PIR comprising foam at an isocyanate index of at least 120, said composition comprising at least an isocyanate composition comprising one or more isocyanate compounds, an isocyanate-reactive composition comprising one or more isocyanate-reactive compounds, at least one PIR promoting catalyst, at least one physical blowing agent with a lambda gas ≤12 mW/m.Math.K at 10° C., at least one CO.sub.2 scavenging compound selected from at least one epoxy compound, and optionally a catalyst promoting epoxy reaction with CO.sub.2 characterized in that the amount of isocyanate-reactive compounds in the reactive composition is at least 10 wt % calculated on the total weight of the reactive composition, or at least more than the amount of epoxy compounds and the molar amount of epoxy compounds in the reactive composition is at least 7.8 times higher than the molar amount of CO.sub.2 formed by the water present in the reactive composition after reaction with isocyanates.

Claims

1. A composition for making a PIR comprising foam at an isocyanate index of at least 120, wherein said composition comprises: a) An isocyanate composition comprising one or more isocyanate compounds, and b) An isocyanate-reactive composition comprising one or more isocyanate-reactive compounds, and c) At least one PIR promoting catalyst, and d) At least one physical blowing agent with a lambda gas ≤12 mW/m.Math.K at 10° C., and e) At least one CO.sub.2 scavenging compound selected from at least one epoxy compound having an equivalent weight lower than 300 g/mol, and f) Optionally a catalyst promoting epoxy reaction with CO.sub.2 Characterized in that the amount of isocyanate-reactive compounds in the reactive composition is at least 10 wt % calculated on the total weight of the reactive composition and the molar amount of epoxy compounds in the reactive composition is at least 7.8 times higher than the molar amount of CO.sub.2 formed by the water present in the reactive composition after reaction with isocyanates.

2. The reactive composition according to claim 1 wherein the amount of isocyanate-reactive compounds in the reactive composition is at least 10 wt % calculated on the total weight of the reactive composition.

3. The reactive composition according to claim 1 wherein the molar amount of epoxy compounds in the reactive composition is at least 10 times higher than the molar amount of CO.sub.2 formed by the water present in the reactive composition after reaction with isocyanates.

4. The reactive composition according to claim 1 wherein the maximum amount of all the epoxy compounds in the reactive composition is <25 wt %, calculated on the total weight of the reactive composition.

5. The reactive composition according to claim 1 wherein the at least one epoxy compound is selected from epoxy compounds having equivalent weight lower than 300 g/mol and wherein the at least one epoxy compound used is liquid at 20° C.

6. The reactive composition according to claim 1 wherein the catalyst used for promoting epoxy reaction with CO.sub.2 is selected from ammonium salts.

7. The reactive composition according to claim 1 wherein the at least one physical blowing agent having a lambda gas value ≤12 mW/m.Math.K@10° C. is selected from an HFO blowing agent, an HCFO blowing agent, a hydrocarbon, and mixtures thereof

8. The reactive composition according to claim 1 wherein the at least one physical blowing agent having a lambda gas value ≤12 mW/m.Math.K@10° C. is selected from chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs), and mixtures thereof.

9. The reactive composition according to claim 1 wherein the polyisocyanate compounds are selected from a toluene diisocyanate, a methylene diphenyl diisocyanate, a polyisocyanate composition comprising a methylene diphenyl diisocyanate, or a mixture of such polyisocyanates.

10. The reactive composition according to claim 1 wherein the one or more isocyanate reactive compounds comprise polyols and polyol mixtures having average hydroxyl numbers of from 50 to 1000 and hydroxyl functionalities of from 2 to 8.

11. The reactive composition according to claim 1 wherein the blowing agent is present in an amount of 1 to 60 parts by weight per hundred parts by weight isocyanate reactive compounds.

12. The reactive composition according to claim 1 further comprising beside the blowing agents having a lambda gas value ≤12 mW/m.Math.K at 10° C. additional blowing agents having a lambda gas value >12 mW/m.Math.K at 10° C. and wherein the ratio of blowing agents having a lambda gas value ≤12 mW/m.Math.K at 10° C. to the additional blowing agents is in the weight ratio 95/5 up to 5/95 calculated on the total weight of all blowing agents.

13. A process for making a PIR comprising insulation foam, said process comprising combining and/or mixing the ingredients of the reactive composition according to claim 1 at an isocyanate index of at least 120, preferably at least 150, more preferably at least 200, most preferably at least 250.

14. The process according to claim 13 further including a step of sealing the foam with a gas diffusion tight sealing wherein at least 50% of the foam surfaces are covered with the gas diffusion tight sealing.

15. The process according to claim 13 wherein the gas diffusion tight sealing is selected from metal foils, gas barrier polymer layers, a thermoplastic polymer, and combinations thereof.

16. The process according to claim 13 further including after sealing the foam a step of ageing the foam, said ageing step includes keeping the foam at a given temperature above room temperature until a stable low lambda value is obtained.

17. A stabilized PIR comprising insulation foam made using the process according to claim 13 wherein the wt % of CO.sub.2 in the stabilized aged foam is between 0 and 2 wt %, calculated on the total weight of the stabilized aged foam.

18. The stabilized PIR comprising insulation foam according to claim 17 having a foam density <45 kg/m.sup.3 and a stabilized thermal conductivity <20 mW/m.Math.K at 10° C.

19. The stabilized PIR comprising insulation foam according to claim 17 having a foam density >45 kg/m.sup.3 and a stabilized thermal conductivity <25 mW/m.Math.K at 10° C.

20. A thermal insulator comprising the polyisocyanurate (PIR) comprising insulation foam according to claim 17.

Description

FIGURES

[0168] FIG. 1 illustrates the influence of the CO.sub.2 scavenger on the lambda value (measured at 10° C.) in function of time (ageing at room temperature) for foams made according to the invention (examples 1 & 2) and for comparative foams (comparative examples 1 & 2).

EXAMPLES

[0169] Chemicals Used: [0170] Polyol: aromatic polyester polyol with OHv=240 mg KOH/g (Stepanpol® PS 2352 from Stepan) [0171] Flame retardant Tris (chloroisopropyl) phosphate (TCPP) [0172] Catalyst 1: Pentamethyldiethylenetriamine (PMDETA) [0173] Catalyst 2 : Potassium octoate based catalyst (Dabco® K15) [0174] Catalyst 3 : Potassium acetate based catalyst (LB catalyst) [0175] Catalyst 4 : Tetrabutylammonium bromide (TBAB, Sigma-Aldrich) [0176] Foam stabilizer: Silicon surfactant (Tegostab® 8494 from Evonik) [0177] Blowing agent: Cyclopentane (CP, Alfa-Aesar) [0178] Water [0179] Epoxy compound: Phenyl Glycidyl Ether (PGE, Sigma-Aldrich) [0180] Polyisocyanate Suprasec® 2085 (S2085 from Huntsman), a high functionality polymeric MDI composition having NCO%=30.5 and an average functionality=2.9

[0181] Fabrication of PIR comprising insulation foams using CO.sub.2 scavenger and Cyclopentane blowing agent (examples 1 & 2) and comparative examples 1&2 using no or limited amount of CO.sub.2 scavenger (illustrating the effect of the CO.sub.2 scavenger)

[0182] The following PIR formulations (Table 1) were foamed in a closed metallic mold (20×20×4 cm.sup.3) pre-heated to 50° C. of which internal surfaces were preliminarily covered with a gas diffusion tight sealing (a multilayer Aluminum comprising foil being impermeable to Air). Demolding was performed after lh and the sealing was removed from the lateral foam sides leaving them open. The resulting foams therefore had their top and bottom surfaces covered with a gas diffusion tight sealing (71.4% of the surfaces of the foams).

[0183] For the foams containing the epoxy compound (PGE), the CO.sub.2/epoxy reaction catalyst (TBAB) was first dissolved inside the epoxy compound before mixing the resulting solution with the rest of the polyol blend prior reaction with the isocyanate, and the weight ratio TBAB/PGE was kept constant at 0.33.

[0184] The amount of reaction mixture inserted inside the mold was adjusted to ensure good mold filling as well as minimal overpacking. The foams were aged at room temperature and their lambda value at 10° C. was measured in a LaserComp Fox200 at regular time intervals until reaching a constant value (stabilized lambda value, ˜100 days). CO.sub.2 levels inside the foams were then determined by cell gas analysis (internally developed method). FTIR (Fourier Transform InfraRed) spectra were also recorded to qualitatively evidence or not the presence of carbonate adducts in the foams (wavenumber ˜1798 cm.sup.−1).

TABLE-US-00001 TABLE 1 Rigid PIR foam formulations Comp. Comp. Ex. 1 Ex. 2 Example 1 Example 2 Chemicals (pbw) (pbw) (pbw) (pbw) PS2352 80.16 80.16 80.16 80.16 TCPP 16 16 16 16 PMDETA 0.1 0.1 0.1 0.1 K15 1.36 1.36 1.36 1.36 LB 0.45 0.45 0.45 0.45 TBAB 0 1.39 7.16 16.21 TB8494 1.6 1.6 1.6 1.6 CP 17.2 17.2 17.2 17.2 Water 0.33 0.33 0.33 0.33 PGE 0 4.17 21.48 48.63 Total polyol 117.2 122.76 145.84 182.04 blend Suprasec ® 2085 170 170 170 170 Iso Index 314 314 314 314 Foam density 53 53 59 76 (kg/m.sup.3) Molar ratio 0 1.5 7.8 17.7 PGE/water

[0185] The lambda values for the 4 foams are plotted in FIG. 1 and additional foam properties are summarized in Table 2. Comparative Example 1 which is free of CO.sub.2 scavenger epoxy compound has the highest aged lambda value and the largest amount of CO.sub.2. Comparative Example 2 which comprises a small amount of epoxy compound in its formulation displays only a negligible decrease in its aged lambda value compared to the epoxy compound-free Comparative Example 1, together with a significant level of residual CO.sub.2. Examples 1 and 2 according to the invention have higher amounts of epoxy compounds and ultimately display lower aged lambda values and significantly lower levels of CO.sub.2 compared to Comparative Examples 1 and 2, indicative of successful CO.sub.2 scavenging. Carbonate group formation was confirmed as well by the well noticeable presence of FTIR absorption peaks at 1798 cm.sup.−1.

[0186] These results evidence that the proper amount of epoxy compound is crucial to significantly scavenge CO.sub.2 and to ultimately achieve improved thermal insulation performance (i.e. lower lambda values), and as a consequence epoxy group/water molar ratios larger than 7.8 have to be used (or in other words the molar amount of epoxy compounds in the reactive composition needs to be at least 7.8 times higher than the molar amount of CO.sub.2 formed by the water).

TABLE-US-00002 TABLE 2 PIR foam properties FTIR Molar ratio carbonate epoxy PGE amount Lambda Lambda Delta signal group/water in starting CO.sub.2 amount (10° C.) fresh (10° C.) aged lambda intensity at in starting formulation in aged foams foams (10° C., 1798 cm.sup.−1 formulation (wt %) foams (wt %) (mW/m .Math. K) (mW/m .Math. K) aged-fresh) (aged foams) Comp. 0 0 2.38 23.7 24.3 +0.6 No Peak Ex. 1 Comp. 1.5 1.4 1.67 22.8 24.0 +1.2 Very Small Ex. 2 Ex. 1 7.8 6.8 0.53 21.8 22.1 +0.3 Small Ex. 2 17.7 13.8 0.05 22.8 21.1 −1.7 Medium