VALVE STEM MADE OF THERMOPLASTIC MATERIAL

Abstract

The present invention relates to a tire valve, in particular a bicycle tire valve, comprising a tubular stem, where the stem consists of a composition (Z1) comprising a thermoplastic (P1) and comprising a filler (F1), and also to a valve stem for the production of a tire valve, where the valve stem is tubular and consists of a composition (Z1) comprising a thermoplastic (P1) and comprising a filler (F1). The present invention further relates to the use of the valve of the invention for the production of a molding comprising an inflatable tube section, in particular an inner tube for a tire, and also to the use of the valve of the invention for the production of a tubeless bicycle tire.

Claims

1. A tire valve comprising a tubular stem, where the stem consists of a composition (Z1) comprising a thermoplastic (P1) and comprising a filler (F1), where the filler (F1) is fibrous.

2. The valve according to claim 1, where the thermoplastic (P1) is a thermoplastic polyurethane.

3. The valve according to claim 1, where the composition (Z1) comprises, based on the entire composition (Z1), a quantity in the range from 5 to 55% by weight of the filler (F1).

4. The valve according to claim 2, where the Shore hardness of the thermoplastic polyurethane is in the range from 85 A to 85 D.

5. The valve according to claim 2, where the modulus of elasticity of the thermoplastic polyurethane is in the range from 500 to 8000 MPa, determined in the tensile test n accordance with DIN EN ISO 527.

6. The valve according to claim 2, where the thermoplastic polyurethane is based on an aromatic isocyanate.

7. The valve according to claim 1, where the valve comprises a valve base made of a thermoplastic material.

8. A valve stem for the production of a tire valve, where the valve stem is tubular and consists of a composition (Z1) comprising a thermoplastic (P1) and comprising a filler (F1), where the filler (F1) is fibrous.

9-11. (canceled)

Description

EXAMPLES

1. Example 1 (Materials Used)

[0124] Chopvantage HP3550 EC10-3,8: Glass fiber from PPG Industries Fiber Glass, Energieweg 3, 9608 PC Westerbroek, The Netherlands. E glass, Filament diameter 10 m, length 3.8 mm.

[0125] TPU 1: TPU of Shore hardness 75 D, based on polytetrahydrofuran (PTHF) with molecular weight (Mn) 1000 daltons, 1,4-butanediol, MDI.

[0126] TPU 2: TPU of Shore hardness 80 D, based on polytetrahydrofuran (PTHF) with molecular weight (Mn) 1000 daltons, 1,4-butanediol, MDI.

[0127] TPU 3: TPU of Shore hardness 60 D, based on polytetrahydrofuran (PTHF) with molecular weight (Mn) von 1000 daltons, 1,4-butanediol, MDI.

[0128] TPU 4: TPU of Shore hardness 65 D, based on polytetrahydrofuran (PTHF) with molecular weight (Mn) von 1000 daltons, 1,4-butanediol, MDI.

[0129] TPU 5: Glass-fiber-filled TPU of Shore hardness 70 D, produced by compounding to incorporate 20% of Chopvantage HP3550 EC10-3,8 glass fiber into TPU 3.

[0130] TPU 6: Glass-fiber-filled TPU of Shore hardness 75 D, produced by compounding to incorporate 20% of Chopvantage HP3550 EC10-3,8 glass fiber into TPU 4.

2. Example 2

[0131] Each of the materials TPU 1, TPU 2, TPU 5 and TPU 6 was used to manufacture a valve stem of length 58 mm and external diameter 6 mm. In each case, bicycle tubes were produced with valves using these valve stems.

3. Example 3

Tube Test on Dynamic Drum Tester

[0132] Brake: Magura HS33

[0133] Wheel: Whizz Wheels DP18 622x15C with Schwalbe high-pressure tubeless tape and temperature sensor

[0134] Tire: Schwalbe ONE V-Guard, Folding 23-622 B/B-SK HS448 OSC 127EPICurrent Standard11600514

[0135] Tube: Schwalbe SV20E EVOLUTION TUBE 18/25-622/630 EK 40 mm, with weight 32 g, tube thickness 0.25 mm, tube internal pressure 8 bar.

[0136] At velocity 25 km/h, the wheel was loaded by braking at 10 V. The temperature increase caused by the braking action was on average to 115 C. (measured in the wheel rim). This corresponds approximately to the dynamic loading arising under practical conditions. The stem experiences stress resulting from both temperature and braking force.

TABLE-US-00001 Material of valve stem Test Comments TPU 1 1 The valve stem buckled 2 The valve stem buckled TPU 2 1 The valve stem buckled 2 The valve stem buckled TPU 5 1 The valve stem did not buckle 2 The valve stem did not buckle TPU 6 1 The valve stem did not buckle 2 The valve stem did not buckle

[0137] The valve stems made of glassfiber-filled TPU are superior to the TPU that is not glassfiber-filled. The glassfiber-filled stems exhibit no deformation of any kind. Buckling of the valve stem is symptomatic of the standard TPU embodiments.

4. Example 4

Flexural TestDetermination of Flexibility and Resilience

[0138] For determination of the abovementioned properties, various tube samples were assembled with tires on a commercially available bicycle wheel. The bicycle wheel was fixed, and an area of 3 mm.sup.2 at a defined point on the valve stem was subjected to load in a conventional tensile/pressure tester (apparatus from Zwick/Roll). The maximum displacement (outward travel of the pressure tester) is 7 mm, starting from contact with the valve stem.

[0139] The bending of the stem, depending on design, is then so great that contact with the area is broken. The average force (N) reached in achieving max. displacement is determined. The range for the stems made of TPUs 1 and 2 is from 170-186N. For the glassfiber-filled stems made of TPUs 5 and 6 it is 108N (TPU 5) and 140N (TPU 6). The glassfiber-reinforced material therefore ensures substantially greater flexibility. The glassfiber-filled stems (TPU 5 and 6) moreover return to the starting position after max. bending. The standard TPUs (TPU 1 and 2) retain the deformation after bending; the material does not recover.

5. Example 5

Deformation Due to Heat in the Static State

[0140] Various tubes with standard TPU stem, and also with glassfiber-filled stems were stored in sunlight at outdoor temperatures of 35 C. The temperature on the black external carcass of the tire was determined every 30 min. All of the standard TPU (TPU 1 and 2) stems exhibited major loss of air due to swelling of the stem. The temperature was about 70 C. The glassfiber-filled stems exhibited no loss of air.

6. Example 6

[0141] High-Pressure (>6 bar) Inflation of a Bicycle Tube

[0142] Bicycle tubes having valve stems with and without glassfiber filler were compared in inflation up to an air pressure of 10 bar. This value corresponds to the upper limit of use in the racing bicycle sector. Inflation was achieved by using two commercially available track pumps, which are secured on the valve stem by means of rubber seal and clamping mechanism. It was found here that in the case of the valves made of thermoplastic without glassfiber filler, these having a smooth surface structure, adhesion between stem and air pump head is inadequate. During high-pressure (>6 bar) inflation the air pump head, secured by means of a clamping mechanism, separates from the valve stem. This makes inflation difficult or impossible.

[0143] The glassfiber-filled valve stems exhibit, by virtue of the additive, substantially greater surface roughness, which ensures intermeshing of the pump head or of the rubber seal. The tubes with glassfiber-filled stem can be inflated up to 9 bar without any undesired separation of the pump head.

TABLE-US-00002 Testing of inflation properties as a function of surface quality Valve type/Pump SKS Topeak Brass valve 10 bar 10 bar Standard TPU 7.3 bar 6.8 bar TPU with glassfiber filler 10 bar 10 bar Pump I: SKS Rennkompressor Pump II: Topeak Joe Blow Sport II Tire: Schwalbe One 23-622 (max. air pressure 10 bar)