Valve for an inflatable hose section

Abstract

Valve for an inflatable flexible tube section comprising a tubular shaft, and also a valve base, connected adhesively and around the entire periphery to an end of the shaft, wherein the valve base has been manufactured from a thermoplastic polyurethane.

Claims

1. A valve for an inflatable flexible tube section comprising a thermoplastic polyurethane, the valve comprising: a tubular shaft, and a valve base connected adhesively and around the entire periphery to an end of the tubular shaft, wherein: the valve base comprises a thermoplastic polyurethane which is a reaction product of (a) isocyanates with (b) polyetherols as compounds reactive toward isocyanates, the polyetherols having a Mn of 0.510.sup.3 g/mol to 10010.sup.3 g/mol, the thermoplastic polyurethane having a shore hardness of from 70 A to 90 A; the tubular shaft comprises a thermoplastic polyurethane having a shore hardness in the range of from 70 A to 95 D, wherein the valve base of the valve is connected adhesively to the inflatable flexible tube section comprising a thermoplastic polyurethane, wherein the inflatable flexible tube section comprises an aperture, and the inflatable flexible tube section is connected adhesively around the aperture and around the entire periphery to the valve base of the valve, in such a way that the connection between an internal space of the inflatable flexible tube section and an internal space of the tubular shaft is sealed off from the environment.

2. The valve according to claim 1, wherein the valve base encloses the tubular shaft in an axial direction to an extent of at least 3 mm.

3. The valve according to claim 1, wherein the valve base protrudes beyond an exterior edge of the tubular shaft in each radial direction at the end of the tubular shaft to an extent that corresponds at least to half of the diameter of the tubular shaft at its lower end.

4. An inflatable flexible tube section comprising a thermoplastic polyurethane, wherein: the inflatable flexible tube section comprises an aperture; and the inflatable flexible tube section is connected adhesively around the aperture and around the entire periphery to the valve base of the valve according to claim 1, in such a way that the connection between the internal space of the flexible tube and the internal space of the shaft is sealed off from the environment.

5. A process for producing a valve according to claim 1, comprising inserting the tubular shaft into a mold and casting around the tubular shaft in the mold to produce the valve base.

6. A process for producing the inflatable flexible tube section according to claim 4, comprising wetting an underside of the valve base with a solvent and then forcing the underside of the valve base onto a surface of the inflatable flexible tube section.

7. The process according to claim 6, wherein the solvent is selected from the group consisting of an ether, a cyclic ether, an amine, an amide, an alcohol and a halogenated hydrocarbon.

8. The process according to claim 7, wherein the solvent comprises at least one selected from the group consisting of methanol, ethanol, isopropanol, dimethylformamide, N-methylpyrrolidone, and tetrahydrofuran.

9. A process for producing the inflatable flexible tube section according to claim 4, comprising connecting the valve base to the inflatable flexible tube section by thermal welding, high-frequency welding, or ultrasound welding.

10. The valve according to claim 1, wherein said the valve base comprises a thermoplastic polyurethane which is a reaction product of (a) isocyanates with (b) polyetherols as compounds reactive toward isocyanates the polyetherols having a Mn of 0.510.sup.3 g/mol to 10010.sup.3 g/mol and (c) chain extenders with a molar mass from 0.0510.sup.3 g/mol to 0.49910.sup.3 g/mol.

11. The valve according to claim 1, wherein said polyetherols have an average functionality of 1.8 to 2.3.

Description

(1) Examples are used below for further explanation of the invention. Neither the examples nor FIG. 1, which is to be considered as a depiction of the principle, represent(s) any restriction of the invention, for example in respect of specific dimensions or design variants of components. FIG. 1 is a diagram of a valve of the invention, comprising a shaft 10 and a valve base 20.

EXAMPLES

(2) The trials used commercially available valve shafts of Sclaverand type with total length 58 mm and external diameter 6 mm. The diameter of the shaft section intended for securing the valve base was greater, 7 mm, over a length of about 4 mm. In the middle of this region there was a circumferential groove of depth about 0.5 mm with rounded U-shaped longitudinal section.

Comparative Example

(3) A valve shaft with the dimensions described above, made of aluminum, was inserted into an injection mold, the mold was closed, and a thermoplastic polyurethane of Shore hardness 80 A (Elastollan 1180 A 10 from BASF Polyurethanes GmbH, Lemforde) was injected onto the material, to form the valve base. As soon as the melt had solidified, the finished valve was removed from the mold and stored at 80 C. for 15 hours. This gave the material its final strength. In the valve thus produced, the valve base could easily be pulled away from the shaft manually. There was inadequate adhesion. The only factor ensuring a certain stability was the interlock by virtue of the groove. However, air would inevitably escape in the event of loading under pressure, for example after pumping to inflate a bicycle tire, since the interlock does not provide a seal.

Inventive Example 1

(4) Another valve shaft as described in the comparative example was connected to the same thermoplastic polyurethane under the same process conditions. The shaft had been manufactured from aluminum and completely anodized. In this valve, adhesion between the valve base and the shaft was so great that the valve base could not be pulled away from the shaft without resultant damage thereto. The connection between shaft and valve base was durable and airtight.

Inventive Example 2

(5) Another valve shaft as described in both of the trials described above was connected to the same thermoplastic polyurethane under the same process conditions. The shaft had been manufactured from a thermoplastic polyurethane of Shore hardness 75 D. Its length was likewise 58 mm and its external diameter was 6 mm. In contrast to the two aluminum shafts, no enlargement had been applied to the diameter of the section thereof intended for securing to the valve base. At a distance of 4 mm from the lower end thereof, there was a groove of width 1 mm and depth about 0.5 mm, with rectangular longitudinal section. There was very good adhesion between valve base and shaft, as was also the case in inventive example 1. The connection between shaft and valve base was durable and airtight.

(6) In all three cases described above, the valve base was oval, with a dimension of 40 mm along its longitudinal axis and 18 mm along its transverse axis. Its height profile corresponded to that depicted qualitatively in FIG. 1. Starting at the edges, its height then increased slowly, and total height at the shaft was 5 mm. The thickness of the material of the valve base in the section covering the shaft was about 2-0.5 mm, decreasing in the axial direction of the shaft upward away from the base.

Inventive Example 3

(7) An aperture of size the same as the internal diameter of the valve was punched into a commercially available bicycle inner tube made of thermoplastic polyurethane (Firma Eclipse Microsystems GmbH, Ebmatingen, Switzerland). The base of a valve of the invention as in inventive example 1 was immersed for less than one second in liquid tetrahydrofuran as solvent. The valve was then placed centrally onto the aperture in the bicycle inner tube and pressed manually onto the material. After a waiting time of about 15 seconds, there was adhesion between the underside of the valve base and the flexible tube surface. After air drying at room temperature for about 60 seconds, during which the tetrahydrofuran evaporated, the final level of adhesion had been obtained. The connection between the valve and the flexible tube was airtight and secure.