Plastic and nonmetallic article shaping or treating: processes – With incorporating dye susceptible material or dyeing workpiece
Patent
1998-08-11
1999-11-16
Tentoni, Leo B.
Plastic and nonmetallic article shaping or treating: processes
With incorporating dye susceptible material or dyeing workpiece
57282, 57310, 264103, 26417212, 26417215, 26417713, 26417719, 2642105, 2642107, 2642108, 26421115, 26421117, D01D 512, D01D 5253, D01D 534, D01F 804
Patent
active
059851929
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method for the manufacture of screwlike bristles from plastic by extruding monofilaments.
Description of the Prior Art
Bristles for brushware of random types evolve their brushing action initially and mainly through the free ends of the bristles, which tear open the dirty surface and remove the dirt by scratching and scraping. When stronger pressure is exerted, the bristles bend round and act with their circumferential surface. They then have a stroking and sliding effect on the surface with a more gentle action.
Besides circular bristles with the aforementioned effects, profile bristles are also known, in which the profile edges have a stronger scraping action when the bristle is bent round. In addition, bristles for car wash brushes having a screwlike profile are known (DE-U-93 19 214, DE-A-1 140 901) where there is a very large pitch of the screws. This is once again intended to reduce the strong scraping action exerted by the profiled bristles, in that locally only a part of the helix is in engagement. Such a bristle with a steep helix can be obtained by twisting a monofilament with a substantially star-shaped cross-section. It is left open in the prior art how this is to take place and in particular lead to a stable bristle with a good re-righting capacity.
It is also known to provide the circumferential surface of conical bristles with a helix or spiral (DE-U-85 22 986). This takes place by the subsequent shaping of the helix or by extruding the bristle. This bristle has in particular the function in the case of hairbrushes the improvement and facilitating of the application of media. Extruded or subsequently profiled bristles must have a significant cross-section so as to ensure an adequate bending resistance. They are therefore pins rather than bristles.
It is finally known (DE-A-16 60 646) to manufacture helical fibers by extruding a monofilament under strong shear stress, so that melt fractures occur. Thus, the helical shape is directly produced at the extruder die and fixed by sudden cooling after the die. Due to the strong shear stress, which deliberately leads to melt fractures, as well as the sudden chilling of the still melt-plastic material, there is a significant deterioration to fiber stability. The fiber cannot be used as bristle material. It is also impossible to influence the pitch of the helix.
SUMMARY OF THE INVENTION
The problem solved by the invention is providing a method with the aid of which it is possible to manufacture screwlike bristles in the same, predeterminable quality as conventional bristles and in an inexpensive manner.
According to a first variant of the invention, the problem of the prior art is solved in that a monofilament is extruded with a cross-section diverging from the circular shape and on drawing off is prestretched, whilst reducing its cross-section, followed by further stretching and then at least part of its length is twisted to a screwlike bristle material and is stabilized by heat shrinkage after twisting. Prestretching takes place immediately on removing the monofilament at the extruder during further stretching after cooling, e.g. after monofilament passage through a water bath.
As a result of the prestretching and subsequent further stretching a profile bristle with strength characteristics such as are known in the case of conventional, unprofiled bristles. As a result of the subsequent twisting round the monofilament axis from the monofilament is obtained a screwlike or helical bristle material. The helix obtained in this way is acquired from the monofilament profile projecting over the circular shape and can either extend over the entire bristle length or only over part of the length thereof. Stabilization after twisting can take place in known manner by the action of an elevated temperature or by the storage of the wound, screwlike bristle material at ambient temperature or a higher temperature, in order to fix the bristle material in the desired shape.
Prefera
REFERENCES:
patent: 4804232 (1989-02-01), Weihrauch
Abstract of Japan 3-289,906 (Dec. 19, 1991).
Coronet-Werke GmbH
Tentoni Leo B.
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