Method and device of the production of brushes

1. A method for producing a bristle from a thermoplastic polymer by injection molding a molten polymer mass into a bristle molding channel, said channel having a predetermined length and a predetermined cross sectional shape along said length, the method comprising the steps of:

(a) injecting the molten polymer mass into said channel under pressure, said pressure being selected in dependence on said cross sectional shape of said channel, a ratio of a largest width of a cross section of said channel to said length of said channel being selected as less than or equal to 1:10,

wherein said injection pressure is 2000 to 5000 bar (2×10 5 kPa to 5×10 5 kPa), and sufficient to provide a specific pressure in a bristle forming channel of more than 300 bar (0.3×10 5 kPa); and

b) venting said channel along said length during step a), wherein a shear flow is established with a core speed of approximately 1000 mm/s in a center of molten polymer mass flow and with a large shearing effect due to wall friction of the molten polymer mass under distinct longitudinal orientation of polymer molecules, at least in a portion of the molten polymer mass proximate a wall of said channel, said longitudinal orientation of the polymer molecules being maintained throughout said length of said channel.

2. The method of claim 1 , wherein said injection pressure is set to support crystal seed formation between neighboring longitudinally oriented molecular sections in dependence on said cross sectional shape and said length of said bristle-molding channel.

3. The method of claim 1 , wherein said bristle-molding channel is cooled.

4. The method of claim 1 , wherein said bristle-molding channel is vented transverse to a flow direction of the molten polymer mass.

5. The method of claim 4 , wherein said bristle-molding channel is vented in several planes disposed transverse to a flow direction of the molten polymer mass.

6. The method of claim 5 , wherein said bristle-molding channel is vented along said length via planes disposed at approximately equal distances.

7. The method of claim 1 , wherein said bristle-molding channel is vented of air displaced by flow pressure of the molten polymer mass.

8. The method of claim 1 , wherein said channel is vented with assistance of an external underpressure.

9. The method of claim 1 , wherein said cross section of said bristle-molding channel remains substantially constant, beginning at an injection side thereof.

10. The method of claim 1 , wherein said cross section of said bristle-molding channel tapers substantially continuously from an injection side thereof.

11. The method of claim 1 , wherein the molten polymer mass is injected into an inlet region which narrows like a nozzle towards said bristle-molding channel to produce an extension flow.

12. The method of claim 1 , wherein said cross sectional shape of said bristle-molding channel has at least one discontinuity configured as a tapering in a flow direction of the molten polymer mass.

13. The method of claim 1 , wherein said cross section of said bristle-molding channel is selected to have a maximum width of ≦3 mm.

14. The method of claim 1 , wherein a ratio of a largest width of said channel to said length of said channel is selected to be ≦1:250.

15. The method of claim 1 , wherein the molten polymer mass is simultaneously injected into several neighboring bristle-molding channels thereby forming a corresponding number of bristles.

16. The method of claim 15 , wherein, the molten polymer mass is injected into neighboring bristle-molding channels while simultaneously forming a connection between at least two bristles.

17. The method of claim 15 , wherein, after injection of the bristles, a molten polymer mass of another polymer is subsequently injected, thereby forming a connection between at least two bristles.

18. The method of claim 15 , wherein the molten polymer mass is injected to form a bristle support which connects at least two or more bristles.

19. The method of claim 16 , wherein the molten polymer mass is injected to form a bristle support which connects the bristles and forms a brush body.

20. The method of claim 18 , wherein at least one further molten polymer mass from another polymer is injected onto said bristle support.

21. The method of claim 15 , wherein a number of bristles are injected with different lengths.

22. The method of claim 15 , wherein a number of bristles are injected with different cross sections.

23. The method of claim 15 , wherein a number of bristles are injected with a cross sectional shape which changes along their lengths.

24. The method of claim 15 , wherein a plurality of bristles are injected with parallel mutual orientation.

25. The method of claim 15 , wherein at least one part of the bristles is injected in a non-parallel fashion.

26. The method of claim 15 , wherein bristles of a same geometry but different bending elasticity (hardness) are produced through injection-molding of different molten polymer masses in same molding channels.

27. The method of claim 1 , wherein the bristles are injected from a polymer or a polymer mixture which has reduced secondary binding forces in a solidified state.

28. The method of claim 1 , wherein the bristles are injected from a polymer including additives which become active during use.