NON ISOCYANATE POLYURETHANE FOAMS

Abstract

A curable isocyanate free formulation for preparing a polyurethane foam. The formulation includes a compound A chosen from multifunctional cyclic carbonates of a formula (I) or a mixture thereof, a compound B chosen from multifunctional cyclic carbonates containing oxyalkylene groups —OR3- of a formula (II) or a mixture thereof, a compound C chosen from multifunctional amines of a formula (III) or a mixture thereof and a compound D chosen from non-reactive blowing agents, as well as a process for preparing a non-isocyanate polyurethane foam, a foam obtainable by this process, compound B, a mixture of compounds A and B, the use of compound B for enhancing the solubility of a non-reactive blowing agent in a compound A and a foamable system having a first part A containing compound A and compound B and a second part B containing compound C, wherein part A and part B are preferably physically separated.

Claims

1. A curable isocyanate free formulation for preparing a polyurethane foam comprising the following compounds: Compound A chosen from multifunctional cyclic carbonates of formula (I) or a mixture thereof: ##STR00016## wherein: i is an integer higher than or equal to 2, in particular from 2 to 10, R.sup.1 is a linear or branched hydrocarbon chain one or several carbon atoms of which may be replaced with an heteroatom, a cycloalkyl, an heterocycle, an aryl or an heteroaryl, said hydrocarbon chain having at least 3 carbon atoms, in particular from 3 to 60 carbon atoms, Compound B chosen from multifunctional cyclic carbonates containing oxyalkylene groups —OR.sup.3— of formula (II), except polypropylene oxide bis-carbonate, or a mixture thereof: ##STR00017## wherein: i′ is an integer higher than or equal to 2, in particular from 2 to 10, R.sup.1′ is a linear or branched hydrocarbon chain one or several carbon atoms of which may be replaced with an heteroatom, a cycloalkyl, an heterocycle, an aryl or an heteroaryl, said hydrocarbon chain having at least 3 carbon atoms, in particular from 3 to 60 carbon atoms, j is an integer from 1 to 10, R.sub.3 is a linear or branched hydrocarbon chain having at least one carbon atom, in particular from 2 to 6 carbon atoms, Compound C chosen from multifunctional amines of formula (III) or a mixture thereof: ##STR00018## wherein: k is an integer higher than or equal to 2, in particular from 2 to 6, R.sup.2 is a linear or branched hydrocarbon chain one or several carbon atoms of which may be replaced with an heteroatom, a cycloalkyl or an heterocycle, said hydrocarbon chain having at least 2 carbon atoms, in particular from 2 to 60 carbon atoms, more particularly from 2 to 20 carbon atoms, even more particularly from 2 to 15 carbon atoms, Compound D chosen from non-reactive blowing agents.

2. The curable isocyanate free formulation according to claim 1, wherein R.sup.1 and R.sup.1′, identical or different, are a linear or branched hydrocarbon chain having 3 to 10 carbon atoms, more particularly from 3 to 6 carbon atoms.

3. The curable isocyanate free formulation according to claim 1, wherein i and i′, identical or different, are integers from 2 to 6, more particularly from 2 to 3.

4. The curable isocyanate free formulation according to claim 1, wherein: Compound A is chosen from a compound of formula (Ia): ##STR00019## Compound B is chosen from compounds of formula (IIa) or a mixture thereof: ##STR00020## wherein: q represents an integer higher than or equal to 1, in particular from 2 to 20, preferably from 2 to 7 (thus 1, 2, 3, 4, 5, 6, 7 or 8), more preferably from 2 to 4, even more preferably equal to 2, and n, m and p, identical or different, represent integers from 1 to 20, preferably from 1 to 10 (thus 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10).

5. The curable isocyanate free formulation according to claim 4, wherein: Compound A is chosen from compounds of formula (Ia) or a mixture thereof and Compound B is chosen from compounds of formula (IIa) or a mixture thereof wherein q=2 and n, m, p are 6 or 7.

6. The curable isocyanate free formulation according to claim 1, wherein the Compound C is chosen from diamines, in particular linear aliphatic diamines, such as 1,2-diamonethane, 1,3-diaminopropane, butane-1,4-diamine, pentane-1,5-diamine, 1,6-diaminohexane, or 1,12 diaminododecane, or cyclic aliphatic diamines, such as isophorondiamine, triamines, or any other polyamines, such as polyethylene imine or dimeric fatty acid diamines.

7. The curable isocyanate free formulation according to claim 1, wherein compound D is chosen from liquids which boiling point is below 100° C., or hydrocarbons such as n-pentane, isopentane and/or cyclopentane, ethers, halogenated hydrocarbons, nitriles, such as 2,2′-azobisisobutyronitrile, nitrogen or carbon dioxide, or mixtures thereof.

8. The curable isocyanate free formulation according to claim 1, further comprising a catalyst as compound E, wherein said catalyst is chosen from amine catalysts, such as 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]undec-7-ene, trimethylhydroxyethyl ethylene diamine, trimethylaminopropylethanolamine, dimethylethanolamine, bis(2-dimethylaminoethyl) ether, triethylenediamine, dimethylaminocyclohexane, N-methyl morpholine, or organometallic catalysts such as stannous octoate, lead octoate, dibutyltin dilaurate, potassium acetate or potassium ethyl-hexoate, or mixtures thereof.

9. A process for preparing a flexible non-isocyanate polyurethane foam comprising the steps of: reacting compounds A and B with compound C in the presence of compound D and compound E so as to form an expanded reaction mixture, curing said expanded reaction mixture so as to form a flexible non-isocyanate polyurethane foam, wherein compounds A, B and C are as defined in claim 1.

10. The process according to claim 9, wherein: compounds A and B are first mixed with compound E and compound C, so as to form a reaction mixture and start the polymerization of said reaction mixture, then compound D is added to this reaction mixture, preferably by maintaining the temperature of the reaction mixture in the range of 20-25° C.

11. A flexible non-isocyanate polyurethane foam obtainable by the process according to claim 9.

12. The flexible non-isocyanate polyurethane foam according to claim 11, further characterized by having an apparent density of less than 160 kg/m.sup.3.

13. The flexible isocyanate-free polyurethane foam according to claim 11, further characterized by having a resilience from 65% to 80%.

14. A compound B chosen from multifunctional cyclic carbonate containing oxyalkylene groups —OR.sup.3— of formula (II) or a mixture thereof: ##STR00021## wherein: i′ is an integer higher than or equal to 1, in particular from 1 to 10, R.sup.1′ is a linear or branched hydrocarbon chain one or several carbon atoms of which may be replaced with an heteroatom, a cycloalkyl, an heterocycle, an aryl or an heteroaryl, said hydrocarbon chain having at least 3 carbon atoms, in particular from 3 to 60 carbon atoms, j is an integer from 1 to 10, in particular from 1 to 7, more particularly from 1 to 4, R.sup.3 is a linear or branched hydrocarbon chain having at least one carbon atom, in particular from 2 to 6 carbon atoms.

15. A compound B chosen from alcoxylated trimethylolpropaneglycidylether carbonates of formula (IIa) or a mixture thereof ##STR00022## wherein: q represents an integer higher than or equal to 1, in particular from 2 to 20, preferably from 2 to 7 (thus 1, 2, 3, 4, 5, 6, 7 or 8), more preferably from 2 to 4, even more preferably equal to 2, and n, m and p, identical or different, represent integers from 1 to 20, preferably from 1 to 10 (thus 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10).

16. A method for enhancing the solubility of a non-reactive blowing agent in a compound A, wherein said method comprises the step of mixing compound B of claim 14 with compound A so as to form a polymeric blend and then mixing said non-reactive blowing agent with said polymeric blend, wherein compound A is chosen from multifunctional cyclic carbonates of formula (I) or a mixture thereof: ##STR00023## wherein: i is an integer higher than or equal to 2, in particular from 2 to 10, R.sup.1 is a linear or branched hydrocarbon chain one or several carbon atoms of which may be replaced with an heteroatom, a cycloalkyl, an heterocycle, an aryl or an heteroaryl, said hydrocarbon chain having at least 3 carbon atoms, in particular from 3 to 60 carbon atoms.

17. A carbonate mixture comprising: Compound A chosen from multifunctional cyclic carbonates of formula (I) or a mixture thereof: ##STR00024## wherein: i is an integer higher than or equal to 2, in particular from 2 to 10, R.sup.1 is a linear or branched hydrocarbon chain one or several carbon atoms of which may be replaced with an heteroatom, a cycloalkyl, an heterocycle, an aryl or an heteroaryl, said hydrocarbon chain having at least 3 carbon atoms, in particular from 3 to 60 carbon atoms, and Compound B chosen from multifunctional cyclic carbonates containing oxyalkylene groups —OR.sup.3— of formula (II), except polypropylene oxide bis-carbonate, or a mixture thereof: ##STR00025## wherein: i′ is an integer higher than or equal to 2, in particular from 2 to 10, R.sup.1′ is a linear or branched hydrocarbon chain one or several carbon atoms of which may be replaced with an heteroatom, a cycloalkyl, an heterocycle, an aryl or an heteroaryl, said hydrocarbon chain having at least 3 carbon atoms, in particular from 3 to 60 carbon atoms, j is an integer from 1 to 10, in particular from 1 to 7, more particularly from 1 to 4, R.sup.3 is a linear or branched hydrocarbon chain having at least one carbon atom, in particular from 2 to 6 carbon atoms.

18. The carbonate mixture of claim 17, wherein: Compound A is chosen from a trimethylolpropaneglycidylether carbonate of formula (Ia): ##STR00026## and Compound B is chosen from alcoxylated trimethylolpropaneglycidylether carbonates of formula (IIa) or a mixture thereof ##STR00027## wherein: q represents an integer higher than or equal to 1, in particular from 2 to 20, preferably from 2 to 7 (thus 1, 2, 3, 4, 5, 6, 7 or 8), more preferably from 2 to 4, even more preferably equal to 2, and n, m and p, identical or different, represent integers from 1 to 20, preferably from 1 to 10 (thus 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10).

19. A foamable system comprising: a first part A containing: Compound A which is chosen from multifunctional cyclic carbonates of formula (I) or a mixture thereof: ##STR00028## wherein: i is an integer higher than or equal to 2, in particular from 2 to 10, R.sup.1 is a linear or branched hydrocarbon chain one or several carbon atoms of which may be replaced with an heteroatom, a cycloalkyl, an heterocycle, an aryl or an heteroaryl, said hydrocarbon chain having at least 3 carbon atoms, in particular from 3 to 60 carbon atoms, Compound B which is chosen from multifunctional cyclic carbonates containing oxyalkylene groups —OR.sup.3— of formula (II), except polypropylene oxide bis-carbonate, or a mixture thereof: ##STR00029## wherein: i′ is an integer higher than or equal to 2, in particular from 2 to 10, R.sup.1′ a linear or branched hydrocarbon chain one or several carbon atoms of which may be replaced with an heteroatom, a cycloalkyl, an heterocycle, an aryl or an heteroaryl, said hydrocarbon chain having at least 3 carbon atoms, in particular from 3 to 60 carbon atoms, j is an integer from 1 to 10, in particular from 1 to 7, more particularly from 1 to 4, R.sup.3 is a linear or branched hydrocarbon chain having at least one carbon atom, in particular from 2 to 6 carbon atoms. a second part B containing compound C chosen from multifunctional amines of formula (III) or a mixture thereof: ##STR00030## wherein: k is an integer higher than or equal to 2, in particular from 2 to 6, R.sup.2 is a linear or branched hydrocarbon chain one or several carbon atoms of which may be replaced with an heteroatom, a cycloalkyl or an heterocycle, said hydrocarbon chain having at least 2 carbon atoms, in particular from 2 to 60 carbon atoms more particularly from 2 to 20 carbon atoms, even more particularly from 2 to 15 carbon atoms, part A and part B being preferably physically separated.

20. The foamable system according to claim 18, further comprising a catalyst as compound E either in part A or in part B, or in a third part C preferably physically separated from part A and part B.

21. The foamable system according to claim 18, further comprising a non-reactive blowing agent as compound D either in part A, in part B or in third part C, or in a fourth part D preferably physically separated from part A, part B and part C.

Description

[0153] The invention is further illustrated but not limited by the following examples.

[0154] FIG. 1 shows the gelation time of the carbonate mixture when combined with HMDA at 80° C. as a function of the weight percentage of TMPGC in the carbonate mixture.

[0155] FIG. 2 shows the glass-transition temperature Tg (squares) and the decomposition temperature Td (triangles) of the foam as a function of the weight percentage of TMPGC in the carbonate mixture.

[0156] FIG. 3 shows a procedure for preparing a foam according to the invention (Example 1).

[0157] FIG. 4 shows a procedure for preparing a foam according to the invention (Example 2).

[0158] FIG. 5 shows the synthesis of ethoxylated trimethylolpropaneglycidylether carbonate of formula (IIb).

EXAMPLE 1

[0159] NIPU foams according to the invention were prepared as described below.

Reactants:

[0160] Trimethylolpropaneglycidylether carbonate of formula (Ia):

##STR00014## [0161] (wherein the average number of glycidylether carbonate groups is 2.6) [0162] Ethoxylated trimethylolpropaneglycidylether carbonate of formula (IIb):

##STR00015##

[0163] wherein n+m+p=19.2 and the average value of n, m, p is 6.4. [0164] HMDA (1,6-diaminohexane).

[0165] Carbonate mixtures composed of TMPGC and ETMPGC were prepared by varying the amount of ETMPGC in the mixture. The influence of the amount of the ETMPGC on the gelation time of the carbonate mixture, and the Tg and Td of the foam was studied.

[0166] FIG. 1 shows the gelation time of the carbonate mixture when combined with HMDA at 80° C. as a function of the weight percentage of TMPGC in the carbonate mixture. The gelation time was determined by rheological oscillatory experiments using plate-plate geometry with 5% deformation and 10 rad s.sup.−1. Gelation time was determined by the crossover of storage (G′) and loss modulus (G″).

[0167] As it can be seen from FIG. 1, 100 wt % of TMPGC together with HMDA (TMPGC/HMDA=24 wt %) yielded a gelation time of 10 min compared to 42 min with 100 wt % of ETMPGC.

[0168] Based on visual and analytical (gelation times) inspection, a carbonate mixture comprising 60 wt % of TMPGC seems to be the most promising system regarding flexible mechanical properties and sufficient short gelation times (of about 14 min).

[0169] NIPU foams were prepared according to the procedure shown in FIG. 3. 1,4-Diazabicyclo[2.2.2]octane (DABCO, 1 wt.-% regarding carbonate mixture) was used as catalyst and Solkane® 365/227 as a blowing agent.

[0170] The carbonate mixture was mixed with DABCO using a KPG stirrer (2000 rpm) at room temperature for 4 min. After adding HMDA, the mixture was continuously stirred without additional heating. After 8 min, when a suitable increased viscosity was achieved and before reaching the gelation point, the blowing agent Solkane (25 wt.-%) was added. The mixture was homogenized for 10 s, poured into a PP cup (cup diameter 5.0 cm) and cured for 14 h at 80° C. The foaming process was completed during the first 30 min. The sample was prepared with a total mass of 17 g. Foam formation was excellent (homogeneous foam with a height of 5.5 cm). The pore size was in the range of 250 μm to 500 μm.

[0171] The glass-transition temperature Tg (squares) and the decomposition temperature Td (triangles) of the foam was determined according to the wt % of ETMPGC. Td was measured by thermogravimetric analysis under air (10 K.Math.min.sup.−1). Tg was measured by differential scanning calorimetry (heating and cooling rate 10 K.Math.min.sup.−1, second heating curve was analyzed). The results are summarized in table 1.

TABLE-US-00001 TABLE 1 Amount of Amount of Td at 30% TMPGC ETMPGC decomposition Sample (wt %) (wt %) Tg (° C.) Td (° C.) 100 (° C.) 1 100 0 26.5 270 328 2 80 20 13.4 267 334 3 60 40 0.9 275 340 4 40 60 −13 283 345 5 20 80 −29.7 307 356 6 0 100 −37 316 362

[0172] FIG. 2 shows as a function of the weight percentage of TMPGC in the carbonate mixture. Tg decreases as the amount of ETMPGC increases. Td increases as the amount of ETMPGC increases, therefore the thermal stability of the foam increases as the amount of ETMPGC increases.

EXAMPLE 2

[0173] NIPU foams according to the invention were prepared in 400 g scale according to the procedure shown in FIG. 4 by using the same ingredients in the same amounts as described in Example 1, sample 3. The polymeric reaction turned out to be highly exothermic. Therefore, a foam mold (alumina: 1 cm wall thickness; 25×25×25 cm, lid: 4 holes with a diameter of 4 mm) provided with external cooling by using an ice water bath in order to maintain the temperature of the reacting mixture between 20 and 25° C. In addition, mixing times after adding HMDA were shortened (at most 5 minutes).

[0174] The foam mold was preheated at 80° C. and removed from the oven at different times before pouring the resin into it.

[0175] With decreasing mixing time and therefore decreasing viscosity of the composition, stronger foaming could be observed. With the longest mixing time of 6 min, only 2 cm foam height could be achieved (sample 1). Reducing the mixing time to 4 min yielded in 8 cm foam height at equal area. The temperature of the mold was qualitatively varied by removing the mold out of the oven at different times before pouring. If the mold is too hot (t.sub.mold=0 min, direct at pouring, 80° C., sample 2), Solkane evaporated rapidly during pouring yielding big pores at the bottom of the foam and in small inhomogeneity. Nearly perfect foam formation with perfect homogeneity of pore (size) was achieved with 4 min mixing and a slightly warm mold (t.sub.mold=4 min, approximately 50° C., sample 3). After curing for 14 h at 80° C. all samples showed no plane and smooth surface.

[0176] Densities were calculated by measuring the weight and the geometry of prepared cuboid samples (see Table 2). The densities (ρ.sub.foam) were in the range of 0.140 g cm.sup.−3 (sample 20) and 0.219 g cm.sup.−3 (sample 18). Compared to standard PU foam (250913-8, I-70, soft foam) supplied by Faurecia with a density of 0.05 g cm.sup.−3 our NIPU foams still need improvement regarding the foaming process. Pore sizes as measured by optical microscopy were in the range of 250 μm.

TABLE-US-00002 TABLE 2 t.sub.mixing t.sub.mold Homogenous Foam height ρ.sub.foam Sample (min) (min) foam? (cm) (g cm.sup.−3) 1 6 6 yes 2 0.219 2 5 0 no 7.5 0.167 3 4 4 yes 8 0.140

[0177] Therefore, it was possible to prepare flexible NIPU foam by using Solkane as blowing agent and a mixture of TMPGC and ETPMGC as cyclic carbonate component. The method of the invention makes it possible to prepare flexible and soft 100% biobased NIPU foam with comparable pore sizes to standard PU foams and with densities of 0.140 g cm.sup.−3.