Vacuum-supported method for the production of polyurethane foam
First Claim
Patent Images
1. A method for the production of a polyurethane foam, comprising the steps of:
- providing an isocyanate-reactive component A comprising a polyol component A1 which further comprises a physical blowing agent T, wherein the physical blowing agent T is present in the isocyanate-reactive component A in the form of an emulsion with the polyol component A1 constituting the continuous phase and droplets of the physical blowing agent T the dispersed phase of the emulsion, wherein the average size of the droplets of the physical blowing agent T is ≧
0.1 μ
m to ≦
20 μ
m, the droplet size being determined by using an optical microscope operating in bright field transmission mode, wherein the polyol component A1 comprises;
A1a;
a polyether polyol with a hydroxyl number of ≧
15 mg KOH/g to ≦
550 mg KOH/g and a functionality of ≧
1.5 to ≦
6.0 obtained by the addition of an epoxide to one or more starter compounds selected from the group of carbohydrates and/or at least difunctional alcohols; and
A1b;
a polyether polyol with a hydroxyl number of ≧
100 mg KOH/g to ≦
550 mg KOH/g and a functionality of ≧
1.5 to ≦
5.0 obtained by the addition of an epoxide to an aromatic amine; and
A1c;
a polyester polyether polyol with a hydroxyl number of ≧
100 mg KOH/g to ≦
450 mg KOH/g and a functionality of ≧
0.1 to ≦
3.5 obtained by the addition of an epoxide to the esterification product of an aromatic dicarboxylic acid derivative and an at least difunctional alcohol;
combining at least the isocyanate-reactive component A and an isocyanate component B, thereby obtaining a polyurethane reaction mixture;
providing the polyurethane reaction mixture in a cavity; and
reducing the pressure within the cavity to a pressure lower than ambient pressure, wherein the pressure is reduced by ≧
1 mbar up to ≦
900 mbar;
wherein the cavity is ventilated to ambient pressure before the gel time of the polyurethane reaction mixture is reached.
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Abstract
The present invention is related to a method for the production of polyurethane foam, comprising the steps of:
- providing an isocyanate-reactive component A comprising a polyol component A1 which further comprises a physical blowing agent T;
- combining at least the isocyanate-reactive component A and an isocyanate component B, thereby obtaining a polyurethane reaction mixture;
- providing the polyurethane reaction mixture in a cavity (11); and
- reducing the pressure within the cavity (11) to a pressure lower than ambient pressure;
characterized in that the cavity (11) is ventilated to ambient pressure before the gel time of the polyurethane reaction mixture is reached.
10 Citations
18 Claims
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1. A method for the production of a polyurethane foam, comprising the steps of:
-
providing an isocyanate-reactive component A comprising a polyol component A1 which further comprises a physical blowing agent T, wherein the physical blowing agent T is present in the isocyanate-reactive component A in the form of an emulsion with the polyol component A1 constituting the continuous phase and droplets of the physical blowing agent T the dispersed phase of the emulsion, wherein the average size of the droplets of the physical blowing agent T is ≧
0.1 μ
m to ≦
20 μ
m, the droplet size being determined by using an optical microscope operating in bright field transmission mode, wherein the polyol component A1 comprises;A1a;
a polyether polyol with a hydroxyl number of ≧
15 mg KOH/g to ≦
550 mg KOH/g and a functionality of ≧
1.5 to ≦
6.0 obtained by the addition of an epoxide to one or more starter compounds selected from the group of carbohydrates and/or at least difunctional alcohols; andA1b;
a polyether polyol with a hydroxyl number of ≧
100 mg KOH/g to ≦
550 mg KOH/g and a functionality of ≧
1.5 to ≦
5.0 obtained by the addition of an epoxide to an aromatic amine; andA1c;
a polyester polyether polyol with a hydroxyl number of ≧
100 mg KOH/g to ≦
450 mg KOH/g and a functionality of ≧
0.1 to ≦
3.5 obtained by the addition of an epoxide to the esterification product of an aromatic dicarboxylic acid derivative and an at least difunctional alcohol;combining at least the isocyanate-reactive component A and an isocyanate component B, thereby obtaining a polyurethane reaction mixture; providing the polyurethane reaction mixture in a cavity; and reducing the pressure within the cavity to a pressure lower than ambient pressure, wherein the pressure is reduced by ≧
1 mbar up to ≦
900 mbar;wherein the cavity is ventilated to ambient pressure before the gel time of the polyurethane reaction mixture is reached.
-
-
2. The method according to claim 1, wherein the pressure within the cavity is reduced before the polyurethane reaction mixture is provided in the cavity.
-
3. The method according to claim 1, wherein the pressure within the cavity is reduced after the polyurethane reaction mixture is provided in the cavity.
-
4. The method according to claim 1, wherein the pressure is reduced by ≧
- 50 mbar to ≦
300 mbar.
- 50 mbar to ≦
-
5. The method according to claim 1, wherein the cavity is ventilated to ambient pressure when 60 to 99% of the gel time of the polyurethane reaction mixture is reached.
-
6. The method according to claim 1, wherein the polyurethane reaction mixture has a gel time of ≦
- 50 seconds.
-
7. The method according to claim 1, wherein before ventilating to ambient pressure, the step of reducing the pressure within the cavity to a pressure lower than ambient pressure is conducted in such a way that after an initial reduction of the pressure, the pressure is allowed to rise as a consequence of an expansion of the polyurethane reaction mixture.
-
8. The method according to claim 1, wherein before ventilating to ambient pressure, the reduced pressure is kept constant.
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9. The method according to claim 1, wherein the pressure within the cavity is adjusted to different levels at different cavity areas by using two individually operatable vacuum systems.
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10. The method according to claim 7, wherein the pressure level within different cavity areas is adjusted, wherein the pressure level within a cavity area having a first shape is adjusted to a first pressure level, wherein the pressure level within a cavity area having a second shape is adjusted to a second pressure level, wherein the first shape is different than the second shape, and wherein the first pressure level is different than the second pressure level.
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11. The method according to claim 9, wherein the physical blowing agent T is present in the isocyanate-reactive component A in the form of an emulsion with the polyol component A1 constituting the continuous phase and droplets of the physical blowing agent T the dispersed phase of the emulsion, wherein the average size of the droplets of the physical blowing agent T is ≧
- 0.1 μ
m to ≦
15 μ
m, the droplet size being determined by using an optical microscope operating in bright field transmission mode.
- 0.1 μ
-
12. The method according to claim 9, wherein the polyol component A1 further comprises:
-
A1c′
;
a polyester polyol with a hydroxyl number of ≧
100 mg KOH/g to ≦
450 mg KOH/g and a functionality of ≧
1.5 to ≦
3.5 obtained by the esterification of a polycarboxylic acid component and a polyalcohol component, wherein the total content of aromatic dicarboxylic acid derivatives employed in the esterification, based on free aromatic dicarboxylic acids, is ≦
48.5 mass-%, based on the total mass of polyalcohol component and polycarboxylic acid component,and/or A1d;
a polyether polyol with a hydroxyl number of ≧
500 mg KOH/g to ≦
1000 mg KOH/g and a functionality of ≧
1.5 to ≦
5.0 obtained by the addition of an epoxide to an aliphatic amine and/or a polyfunctional alcohol, and/orA1e;
a di-, tri- or tetrafunctional aminic or alcoholic chain extender or cross-linker.
-
-
13. The method according to claim 1, wherein the physical blowing agent T is selected from the group consisting of hydrocarbons, halogenated ethers, perfluorinated hydrocarbons with 1 to 6 carbon atoms and mixtures thereof.
-
14. The method according to claim 9, wherein the mass ratio of A1:
- T is ≧
5;
1 to ≦
12;
1.
- T is ≧
-
15. The method according to claim 9, wherein the polyol component Al has a viscosity according to EN ISO 3219 at 20°
- C. of ≧
1000 mPas to ≦
18000 mPas.
- C. of ≧
-
16. The method according to claim 1, wherein the isocyanate-reactive component A further comprises:
-
A2;
water;A3;
at least one stabilizer selected from the group of polyether polydimethylsiloxane copolymers; andA4;
at least one catalyst selected from the group consisting of triethylenediamine, N,N-dimethylcyclohexylamine, tetramethylenediamine, 1-methyl-4-dimethylaminoethylpiperazine, triethylamine, tributylamine, dimethylbenzylamine, N,N′
N″
-tris-(dimethylaminopropyl)hexahydrotriazine, dimethylaminopropylformamide, N,N,N′
,N′
-tetramethylethylenediamine, N,N,N′
, N′
-tetramethylbutanediamine, tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane, bis(dimethylaminopropyl) urea, N-methylmorpholine, N-ethylmorpholine, N-cyclohexylmorpholine, 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, triethanolamine, diethanolamine, triisopropanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, and dimethylethanolamine.
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17. The method according to claim 1, wherein the isocyanate component B comprises:
-
B1;
at least one isocyanate selected from the group consisting of toluylene diisocyanate, diphenylmethane diisocyanate, polyphenylpolymethylene polyisocyanate, xylylene diisocyanate, naphthylene diisocyanate, hexamethylene diisocyanate, diisocyanatodicylclohexylmethane, and isophorone diisocyanate; and
/orB2;
an isocyanate-terminated prepolymer obtained from at least one polyisocyanate B1 and at least one isocyanate reactive compound selected from the group consisting of;A1c′
;
a polyester polyol with a hydroxyl number of ≧
100 mg KOH/g to ≦
450 mg KOH/g and a functionality of ≧
1.5 to ≦
3.5 obtained by the esterification of a polycarboxylic acid component and a polyalcohol component, wherein the total content of aromatic dicarboxylic acid derivatives employed in the esterification, based on free aromatic dicarboxylic acids, is ≧
48.5 mass-%, based on the total mass of polyalcohol component and polycarboxylic acid component;A1d;
a polyether polyol with a hydroxyl number of ≧
500 mg KOH/g to ≦
1000 mg KOH/g and a functionality of ≧
1.5 to ≦
5.0 obtained by the addition of an epoxide to an aliphatic amine and/or a polyfunctional alcohol; andA1f;
a polyether carbonate polyol with a functionality of ≧
1.5 to ≦
8.0 and a number average molecular weight of ≧
500 g/mol to ≦
10000 g/mol.
-
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18. The method according to claim 1, wherein the cavity into which the polyurethane reaction mixture is provided is a refrigerator insulation frame.
Specification