Motor-vehicle top

1. A method of making a flexibly configured motor-vehicle convertible top comprising a flexible cover layer forming an outer face of the convertible top and having a cutout that holds at least one window, a circumferential inner edge of the flexible cover layer around the cutout being connected to an outer window edge by a polyurethane bead that is synthesized in a polyaddition reaction by reacting an isocyanate component with a polyol component, comprising the steps of:

a) providing a flexible cover layer with a cutout therein in a mold;

b) providing at least one window in the cutout;

c) incorporating a polyurethane sealing compound made of two components, namely an isocyanate component and a polyol component in the form of a polyether polyol or a polyester polyol, into the mold in an intermediate space between a circumferential edge region of the flexible cover layer and an outer window edge, wherein the polyol component comprises at least the following constituents:

a) polyetherols or polyesterols;

b) a propellant;

c) a lead-free catalyst;

d) reacting the two components in a polyaddition reaction at a temperature below 110° C. to form a polyurethane bead which provides a durable, mechanically secure and leak-proof connection between the circumferential edge region of the flexible cover layer and the at least one window; and

e) removing the convertible top that was formed from the mold.

2. The method according to claim 1 , further comprising during steps a)-e):

maintaining the mold at a temperature below 110° C.

3. The method according to claim 1 , wherein a fraction of the lead-free catalyst is 0.05-2 wt. %, relative to the total weight of the polyol component.

4. The method according to claim 1 , wherein according to step d) the two components are reacted at a temperature below 85° C.

5. The method according to claim 2 , wherein the mold is maintained at a temperature below 85° C.

6. The method according to claim 1 , wherein the flexible cover layer is a textile.

7. The method according to claim 1 wherein the lead-free catalyst used to prepare the polyurethane bead includes a lead-free metal compound or an amine.

8. The method according to claim 7 wherein the lead-free metal compound is a tin compound, a bismuth compound, a thallium compound, a zinc compound or a rare earth compound.

9. The method according to claim 7 wherein the lead-free metal compound is an organic metal compound.

10. The method according to claim 9 wherein the organic metal compound is a tin salt of a carboxylic acid or a bismuth carboxylate.

11. The method according to claim 10 wherein the bismuth carboxylate is bismuth acetate, bismuth oleate, bismuth octoate, or bismuth neodecanoate.

12. The method according to claim 7 wherein the lead-free catalyst used to prepare the polyurethane bead is an amine selected from the group consisting of a tertiary amine, a piperidine, an alkanolamine and mixtures of these materials.

13. The method according to claim 12 wherein the lead-free catalyst used to prepare the polyurethane bead is a tertiary amine selected from the group consisting of sebacinic acid bis(1,2,2,6,6-pentamethyl-4-5 piperidinyl)ester, 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, 4-(4-oxo-1,2,3,4,6,7,12,12b-octahydropyrido[2,1-a]-p-carbolin-12b-yl)butyric acid, 1,8-diazabicyclo[5.4.0]undec-7-ene, triethylamine, tributylamine, dimethylbenzylamine, N-methyl-, N-ethyl- or N-cyclohexyl-morpholine, N,N,N′N′-tetramethyl ethyldiamine, N,N,N′N′-tetramethyl butanediamine, N,N,N′N′-tetramethyl hexanediamine, pentamethyl diethylenetriamine, tetramethyl diaminoethylether, bis-(dimethylaminopropyl) urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azobicyclo(3.3.0)-octane, 1,4-diaza-bicyclo-(2.2.2)-octane, DBU (1,5-diaza-bicyclo[5.4.0]undec-5-ene), malonic acid-2-formalamino-2-[3,5-di-t-butyl-4-hydroxybenzyl]-diethyl(ester), [4,4-Dimethyl-5-(2,3,3-trimethyl-5-methylthio-5-pyrrolin-2-ylmethylene)-5-pyrrolin-2-ylthio]-acetic acid-tert.-butyl-ester, 10-oxo-5,5-dimethyl-5-sila-5,10-dihydro-5H-benzo[e]pyrido[3,4-b]azepine, and decahydroisoquinoline-3-carboxyl acid methylester.

14. The method according to claim 12 wherein the lead-free catalyst used to prepare the polyurethane bead is a piperidine selected from the group consisting of 1-(1-cyclopropyl-pentyl)piperidine and bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate.

15. The method according to claim 12 wherein the lead-free catalyst used to prepare the polyurethane bead is an alkanolamine selected from the group consisting of triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine, and N,N-dimethylethanolamine.

16. The method according to claim 1 wherein the addition reaction occurs at a temperature below 85° C.

17. The flexibly configured motor vehicle convertible top prepared according to the method defined in claim 1 .

18. A flexibly configured motor-vehicle convertible top comprising a flexible cover layer forming an outer face of the convertible top and having a cutout that holds at least one window, a circumferential inner edge of the flexible cover layer around the cutout being connected to an outer window edge by a polyurethane bead that is synthesized in a polyaddition reaction by reacting an isocyanate component with a polyol component, the polyol component comprising at least the following constituents:

a) a polyol in the form of a polyether polyol or a polyester polyol;

b) a propellant;

c) a lead-free catalyst, wherein the polyurethane bead provides a durable, mechanically secure and leak-proof connection between the circumferential edge region of the flexible cover layer and the at least one window; and

d) pigments that produce the effect that the color of the synthesized polyurethane bead is approximately the corresponding color of the outer face of the convertible top, or matches it.

19. The flexibly configured motor-vehicle convertible top defined in claim 18 wherein the at least one window is a rear window.

20. The flexibly configured motor-vehicle convertible top according to claim 18 , wherein the color of the corresponding outer face of the convertible top and the color of the polyurethane bead are of a color that is not black.

21. The flexibly configured motor-vehicle convertible top according to claim 18 , wherein the flexible cover layer is a textile.

22. A flexibly configured motor-vehicle convertible top comprising a flexible cover layer forming an outer face of the convertible top and having a cutout that holds at least one window, a circumferential inner edge of the flexible cover layer around the cutout being connected to an outer window edge by a polyurethane bead that is synthesized in a polyaddition reaction by reacting an isocyanate component with a polyol component, the polyol component comprising at least the following constituents:

a) a polyol in the form of a polyether polyol or a polyester polyol;

b) a propellant; and

c) a lead-free catalyst, wherein the polyurethane bead provides a durable, mechanically secure and leak-proof connection between the circumferential edge region of the flexible cover layer and the at least one window.