MXPA98002011A - Process for the manufacture of espira pigs - Google Patents

Abstract

The present invention relates to a method for the manufacture of spiral bristles by extrusion of monofilaments. In order to provide a method with which spiral bristles can be inexpensively manufactured in the same manner as conventional bristles with an identifiable, predeterminable quality, a monofilament having a non-circular cross-section is extruded and pre-stretched after its extraction, accompanied by a reduction in its cross section, followed by additional stretching, twisting to a spiral bristle material over at least part of its length and then shrinkage stabilization. It is possible to extrude a monofilament with an oval or polygon-shaped cross section having a core and at least one axially parallel projection. According to a further method, at least two monofilaments are pre-stretched and pulled out by pulling, accompanied by a reduction in their cross section, followed by additional stretching, twisting together to provide spiral bristle material and stabilization by lime shrinkage

Description

PROCESS FOR THE MANUFACTURE OF SPIRAL PIGS DESCRIPTION OF THE INVENTION The invention relates to a method for the manufacture of plastic spiral bristles by extrusion of monofilaments. The bristles for brushes of random types have evolved with respect to their initial brushing action and mainly through the free ends of the bristles, which openly tear the dirty surface and eliminate the residues by scraping and scraping When a strong pressure is exerted, the bristles are curved and act with their circumferential surface They have an effect of incidence and of sliding on the surface with a smoother action In addition, the circular bristles with the effects mentioned before, there are also known bristles with profile, in which the edges of profile have a stronger scraping action when the bristles are curved In addition, there are known bristles for brushes for car washes having a spiral profile (DE-U-93 19 214, DE-A-1 140 901) where there is a very large step of the spirals. This, once again, is designed to reduce the strong scraping action exerted by the profiled bristles, in REF: 26893 as only a part of the propeller is in contact locally. Such a bristle with an open helix can be obtained by twisting a monofilament with a substantially star-shaped cross section. The way in which this can be done and in particular producing a stable bristle with a good straightening ability is left open in the prior art. 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 extrusion of the bristle. This sow has, in particular, the function in the case of hair brushes to improve and facilitate the application of means. The extruded or profiled bristles subsequently must have a significant cross section in order to ensure adequate resistance to bending. Therefore, they are rather spikes, instead of bristles. Finally, it is known (DE-A-16 60 646) to manufacture helical fibers by extruding a monofilament under a strong shear stress, so that melt fractures can occur. Therefore, the helical shape is produced directly in the die of the extruder and is fixed by sudden cooling after the punching. Due to the strong shear stress, which leads deliberately to melt fractures, as well as to a sudden cooling of the plastic material still melted, there is a significant deterioration of the stability of the fiber. The fiber can not be used as a material for bristles. It is also impossible to alter the pitch of the propeller. The problem of the invention is to propose a method with the help of which it is possible to manufacture spiral bristles with the same predeterminable quality in comparison with conventional bristles, and in a cheap way. According to a first variant of the invention, this problem is solved insofar as a monofilament with a cross section that diverges from the circular shape is extruded and when extracted by pulling it is prestretched, while its cross section is reduced followed by further stretching and then at least part of its length is twisted to a spiral bristle material and stabilized by heat shrinkage after twisting. The pre-stretching takes place immediately upon removal of the monofilament in the extruder during further stretching after cooling, for example, after the passage of the monofilament through a water bath. As a result of the subsequent pre-stretching and subsequent stretching, a profiled bristle is produced, with strength characteristics such as those known in the conventional bristle casing without profile. As a result of the subsequent rounded twist, the monofilament axis from the monofilament yields a spiral or helical bristle material. The propeller obtained in this way is acquired from the monofilament profile which projects on the circular shape and can extend over the entire length of the bristle or only over part of the length of the bristle. Stabilization after twisting can be obtained in known manner by the action of an elevated temperature or by storing the spiral bristle material, wound at room temperature or at a higher temperature, in order to fix the bristle material in the desired shape. Preferably, after further stretching and before twisting, the monofilament is pre-stabilized by shrinkage with heat. During the pre-stabilization, the monofilament is subjected to heat action and then cooled, so that the monofilament shrinks. Together with the additional stabilization, after twisting, it is ensured that the torsion of the monofilament is fixed permanently. The monofilament produced by extrusion may have an oval or polygon-shaped cross section. In the case of an oval cross section with a torsion center on the shaft, a bristle material is obtained-with two helices running on the surface. With a cross section in the form of a polygon, there are numerous propellers corresponding to the angle number. Preferably, a rectangular and in particular square cross section is chosen, so that four helices are formed in the circumferential surface or sheath. Instead of this, it is possible to extrude and twist a monofilament with a core and at least one axially parallel projection. In this case, a bristle material with propellers is obtained, whose height can be pre-selected according to the height of the projection, so that comparatively deep channels are formed on the bristle. For certain uses, it must be ensured that the user recognizes those brushes that have spiral bristles that act in a particularly abrasive manner and that do not use them by mistake, as would be the case, for example, with toothbrushes for the treatment of sensitive gums. In a further development of the invention, at least one protrusion of at least one edge of the polygon-shaped cross-section differs as regards color of the monofilament core, to the extent that plastics with different colors are extruded, for example, a bristle which is transparent white in the nucleus with a helix that has a signal or an indicator color. If pigments are used for staining purposes, the propeller has a higher hardness and at the same time a more abrasive surface. Preferably, the core and at least one projection or at least one edge of the cross section in the form of a polygon is made of a different plastic. As a result, the resulting propeller can be adapted to specific conditions of use, particularly with respect to its hardness. In the case of projections made of a relatively soft material, it is possible, for example, to carefully remove the carpet residues. A relatively hard material for the projection or projections makes it possible, for example, for dental care purposes, to carry out an efficient cleaning of the teeth. An intensive brushing action can be obtained, for example, to remove tartar with flanges made of abrasive material. Information may be provided to the user regarding the brushing characteristics of the particular brush by a color design different from the core and the protrusions. With certain brushes it is necessary that the bristles have a predetermined stiffness. A stiffness adaptation can be obtained in a preferred development of the invention, if the monofilament of the core and the surrounding sheath are extruded in different plastics. As a result of the choice of materials, for example, the core may have typical properties of the bristles with respect to bending ability, while the sheath has more suitable characteristics for the proposed use. The projections on the cover can be made of the same material or a different material. Another solution to the problem of the invention is based on the extrusion of monofilaments with a cross section, for example circular. Such a method is characterized in that at least two monofilaments are prestretched when they are extracted, accompanied by a reduction of their cross section and subsequently further stretched and then twisted together to provide a spiral bristle material and then stabilized by heat shrinkage, after twisting. Therefore, in this case, the spiral profile circumferential surface of the bristle is obtained through at least two monofilaments twisted together having a random cross section. Its stability results from the manufacturing process conventionally used for bristles. Here, again the monofilaments can be stabilized by heat shrinking followed by additional stretching and before twisting. This stabilization can also take place by the action of elevated temperature or by storing the bristle material wound at room temperature or at a higher temperature. The brushing action depends, for example, on the extension of the torsion, in relation to the effective length of a bristle or the bristle material, that is, of the passage of the helix that is formed as a result of the torsion. It has been found that the propeller pitch must not exceed twice the effective length of the bristle, so that, along an effective length, there is a helix pitch of 180 °. Preferably, however, the helix has a smaller pitch, which can extend to the diameter of the bristle material. In the case of toothbrushes it has been shown that it is favorable to adopt a step in which at least two are produced, and preferably three to five turns per centimeter of bristle length. According to a further development of the invention, the monofilament or the monofilaments are made of an elastic plastic. In this way, the bristles produced from a bristle material can be expanded longitudinally, which leads to a reduction in their diameter so that, for example, when they are used in toothbrushes or as interoaltal cleaners, they can be introduced into the toothbrush. a space between the teeth, but do not get stuck in the latter. When pulled out by pulling, the bristles expand and can be twisted further. The bristle material produced according to the invention can be used with particular advantage in numerous brushes. Therefore, the deepest spaces located between the propellers on the surface are particularly suitable for receiving and storing the residues that are detached during brushing and which are only discharged at the end of the brush path. This advantageous action occurs, for example, with carpet brushes, brushes for vacuum cleaners, polishing brushes, etc. In addition, the spaces formed between the helices can be used to retain means to be applied. This is the case, for example, with hair brushes, paint brushes, cosmetic brushes, etc. Finally, the cleaning action different from the ends of the bristles and the flanks or sides of the helices can advantageously be combined in many cases. This applies, for example, with toothbrushes, massage brushes, brushes or brushes, swabs, brushes to remove deposits, etc. In addition, the spiral bristles or such bristles combined in groups can be used with particular advantage as interdental cleaners, which, as a result of a back and forth movement, has a much better cleaning action in the interdental spaces, because it continuously changes the sections cross-cutting that come into action. Even if such an interdental cleaner gets stuck in tight spaces, it would not tear, but would instead slip easily by twisting. Finally, a very smooth treatment can be obtained if the cross section of the helix is rounded correspondingly. In the case of an interdental cleaner, additional advantages are obtained if it is only twisted over part of its length. The non-twisted area has smaller cross-sectional dimensions and therefore can be more easily inserted into a space between the teeth. The introduction can be facilitated more if the area is not twisted, at least zonally, has a cross section which is flattened, for example by pressing. In order to allow the action of a brush to be adapted to given working conditions, the spiral bristles can be combined with bristles having other configurations and can be processed together.

It is noted that in relation to this date, the best method known to the applicant for carrying out said invention is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (15)

1. A method for manufacturing spiral bristles from plastic by extruding monofilaments, the method is characterized in that the monofilament has a noncircular cross section and is extruded and, when extracted, is pre-stretched, accompanied by a reduction in its cross-section It is then stretched and then twisted over at least part of its length to a spiral bristle material and, after twisting, is stabilized by shrinkage with heat.

2. The method according to claim 1, characterized in that the monofilament is pre-stabilized by shrinking with heat after further stretching and before twisting.

3. The method according to claim 1, characterized in that the stabilization takes place by storing the wound spiral bristle material.

4. The method according to claim 1, characterized in that a monofilament with an oval or polygon-shaped cross section is extruded.

5. The method according to claim 4, characterized in that a monofilament with a quadrangular cross-section, preferably square, is extruded.

6. The method according to claim 1 or 4, characterized in that a monofilament with a core and at least one axially parallel projection is extruded.

7. The method according to one of claims 3 or 6, characterized in that at least one projection or at least one edge of the polygon-shaped cross-section has a different color with respect to the monofilament core, and that the plastics are coextruded with different colors.

8. The method according to claim 6 or 7, characterized in that the core and at least one projection or at least one edge of the polygon-shaped cross section are coextruded from different plastics.

9. The method according to claim 1 or 4, characterized in that the monofilament is coextruded from a core and a surrounding sleeve of different plastics.

10. A method for the manufacture of spiral bristles by extrusion of monofilaments, the method is characterized in that at least two monofilaments are pre-stretched in one extraction, accompanied by a reduction in their cross-section, followed by additional stretching and twisting together to provide a material of spiral bristle and stabilize, after twisting, by shrinking with heat.

11. The method according to claim 10, characterized in that after further stretching, the monofilaments are pre-stabilized by shrinkage with heat.

12. The method according to claim 10 or 11, characterized in that the stabilization takes place by storing the rolled bristle material at an optionally high temperature.

13. The method according to claim 1 or 10, characterized in that the monofilament or the monofilaments are made of an elastic plastic.

14. The method according to claim 1 or 10, characterized in that the monofilament is twisted with at least two turns per cm.

15. The method according to claim 14, characterized in that the monofilament is twisted with three to five turns per cm.