UA57814C2 - Monofilament, method for making bristles and interdental cleaning elements and brush articles and interdental cleaning elements made of such monofilament - Google Patents

Abstract

The invention relates to a monofil which has reduced secondary bonding forces and which consists of at least two coextruded polymers, for producing bristles or interdental cleaning elements which can be slit in an essentially axial direction by means of mechanical forces. The aim of the invention is to obtain defined slits or flags. To this end, the two polymers contained in the monofil have a geometrically regular arrangement with the boundary layers in which the reduced secondary bonding forces are present running in an essentially axial direction.

Description

Description of the invention

The invention relates to a monofilament with reduced secondary adhesion forces of at least two polymers, 2 collectively extruded in the correct geometrical ratio with the edge surfaces elongated in the essentially axial direction in order to obtain bristles or interdental cleaning elements capable of detaching essentially along the axis under the action of mechanical forces. The invention also relates to a method of obtaining bristles or interdental cleaning elements from such monofibers, bristle products from such bristles and interdental cleaning elements. 70 Bristles for bristle products of various types, for example, hygienic and toothbrushes, household brushes, industrial brushes, paint brushes, etc., are now mainly produced from polymers by extruding polymer melts into continuous monofibers, which are drawn and, if desired, stabilized. Then, bristles are obtained from such monofibers by cutting them to the required length. As a rule, monofibers, like bristles, have a circular cylindrical cross section. Bristles with other cross-sections, such as oval or 12 polygonal, are known for special purposes. Monofilaments for them are extruded with the appropriate profile.

In many cases, it is desirable to use bristles with a fibrous, in particular, fine-fiber structure. This has a city, for example, in brushes intended for applying media on the surface or similar, that is, in paint brushes. Even if a fluffy structure is needed, the bristles should be fine-fibered. Recently, dentists have found that ordinary toothbrush bristles do not have a sufficient cleaning effect, because they cannot penetrate into the fine cracks on the surface of the teeth, but only slide along them. This also happens when removing impurities from the interdental cavities.

In order to obtain a sufficiently fibrous structure, it was already proposed to extrude a monofiber from a mixture of polymers. During extrusion and subsequent drawing, polymer molecules are oriented along the longitudinal axis of the monofiber. Primary adhesion forces, that is, forces acting in the longitudinal direction, ensure high tensile strength. The longitudinal orientation of the molecules also gives the desired flexibility when bending. In Ge) monofibers made from one polymer, the so-called secondary adhesion forces, i.e., forces acting across the orientation of the molecules, are sufficient to prevent loosening or splitting of the fiber or bristle. In the case of monofilaments made of two different polymers, between the molecular chains of the polymers in the process of stretching, areas of slippage appear, in which the secondary adhesion forces are weakened. Such M monofilament or bristle obtained in a similar way can loosen under the action of mechanical forces caused by a knife or similar tool. Bristles, so-called flags, of irregular shape, irregular cross-section with a fringed surrounding surface are produced. In a large bundle of such bristles, a fluffy structure with a good degree of absorption is probably formed, but the flags have unpredictable food-strength properties. They fray, break or get tangled. Therefore, such loose bristles are unsatisfactory and even unusable in many cases. For hygienic reasons, their use in toothbrushes is risky.

The same shortcomings occur in the well-known bristle structure (MU097/14830), which consists of a core and a shell and is obtained by the combined extrusion of two different polymers. The shell material is mechanically or chemically "removed from the working edge with the formation of a deep pocket that serves to receive toothpaste or paint. C 70 In addition, a description is given of flags obtained by loosening the shell material to such an extent that it protrudes beyond the core. Such loosening is carried out in a well-known way - cutting with a knife. The same irregular structure is preserved in the bristles obtained from.

Especially for toothbrushes, bristles consisting of a plurality of fine fibers similar to textile fibers and covering their shells were proposed (German application 94 08 268 01). The shell and fibers can be co-extruded as a single filament. After cutting the bristles of the sheath at the working end, the bristles are removed by mechanical processing or cutting, releasing the fibers on a short length. Not to mention the technological complexity of obtaining such bristles, the possibilities of their use are limited. It is especially unacceptable that their behavior during bending changes dramatically at the point of transition from the fibers to the shell. If such bristles are used in paint brushes, they can damage the surface with the sharp edge of this transition. -k 70 The same occurs in toothbrushes when acting on teeth and gums. In addition, such fibers do not bend well, so they cannot penetrate into deep cavities, interdental cavities, etc. Under the influence of constant loads, the fiber

T" on the edge of the shell break easily.

MU/096/39117 describes an interdental cleaning element made of monofibers collectively extruded in the appropriate geometric ratios. Each monofilament consists of at least two polymers, which reduces secondary adhesion forces at the boundaries of adjacent monofilaments. Secondary coupling forces are weakened under

GF) by the action of axial tensile forces, which leads to the formation of a fluffy silky structure from a set of fibers. o Conventional textile fibers (US patent C 117,362) with a glossy, acute-angled structure are obtained by co-extruding different polymers, each of which has the desired cross-sectional shape, and which are attached to each other on adjacent surfaces and are separated by introducing a solvent that dissolves one of the polymers.

The basis of this invention is the task of creating a monofilament from at least two co-extruded polymers, suitable for obtaining split bristles or interdental cleaning elements, which has predictable strength characteristics and has flags or slots in a given number and with a shape and size that can be determined. The invention is also aimed at creating a method of obtaining bristles or interdental 62 distil elements from such monofibers.

A monofilament that meets these requirements and has the features of the limiting part of item 1 of the formula differs in that, in accordance with the invention, the edge surfaces are boundary layers with reduced secondary adhesion forces, and the monofilament is a matrix of polymers, the physicochemical properties of which determine properties of a bristle or an interdental cleaning element, while the second polymer is introduced into the matrix in the form of a thin boundary layer.

Thanks to this geometry of the boundary layers, it becomes possible to predict exactly how the monofiber, from which, for example, an interdental cleaning element or a bristle is obtained by cutting to the required length, will be destroyed or split under the action of mechanical forces. The 7/0 slots or flags appear precisely with a pre-known outline given by the geometry of the extruded product. Since the boundary layers lie in the longitudinal direction of the monofilament, a particular flag always has the same shape and the same cross-section along its entire length. Therefore, all flags have the same strength characteristics, in particular, the same bending behavior and the same tensile strength. However, with an appropriately specified geometry, flags with different cross-sections can be obtained. Since the monofilament or bristle under the action of /5 mechanical forces splits exactly along the boundary layers and only along them, the flags form edges on the working surfaces in accordance with their intersection, which contributes to the cleaning action. A bristle split in this way, accordingly, works more efficiently with its circumferential surface than that known with haphazardly arranged flags. Uniform shapes prevent excessive spread of bristles. Each bristle in a densely packed tuft regains its monofilament form, and the presence of flagella is manifested only under the action of axial or radial pressure.

This makes it possible to obtain bristles with flags that have the given properties of ordinary bristles.

During splitting, new fine particles are not formed or almost not formed, so there is no need for thorough cleaning of the bristles. Monofibers for interdental cleaning elements with correctly positioned and clearly split flags are obtained, which provides a guarantee against further splitting or fissure formation.

The polymer of both the matrix and thin layers can also be a copolymer or a mixture of polymers. The advantages of i) above are especially clear when the thin layers at least partially have a matrix polymer. In this case, the polymer of the bristles is destroyed under the action of the applied force at the weakest point - approximately in the center of the thin layers, but the adhesiveness of the part of the matrix polymer in the thin layer on the created neighboring flags is sufficient to prevent the formation of small particles.

Mostly thin layers have a thickness of several microns. Experiments have shown that thin layers can be extruded together with the matrix polymer

The two polymers can be present in thin layers in approximately equal amounts.

The choice of a specific geometry is determined by the necessary characteristics of the bristles or the interdental cleaning element. Thus, thin layers in the matrix can be drawn to the circumference of the monofilament so that the monofilament can be split or cleaved with a relatively small force.

It is possible, on the contrary, that the thin layers end inside the matrix at some distance from the circumference of the monofiber. In this case, it is necessary to make a little more effort, but the flags formed, including in the marginal part, have the material of the matrix, that is, they have the same wear characteristics as the shell of the bristles or " flags. It is possible that the monofilament matrix has a third polymer, included in the specified matrix and serving mainly to influence the strength characteristics of the obtained flags. ;" Usually monofilament for bristles is round, but it can have a non-round cross-section. Polygonal cross-sections, which are more effective in cleaning action than round ones, should be noted.

In this case, the thin layers can reach the corners of the polygonal section so that they come out with relatively sharp edges with an angle of less than 90".

In a preferred embodiment of the invention, the matrix has polyamide, and the thin layers have polyolefin, in particular, polypropylene or polyethylene. Such a combination of materials provides sufficiently large secondary adhesion forces in the connections to prevent untimely wear or loosening during processing and operation of the bristles.

However, such a combination of polymers breaks when a deliberately significant force is applied. - The method of obtaining bristles from the indicated monofiber in accordance with the invention includes the following stages: "i" collectively extrude at least two polymers into a monofiber, stretch and, if desired, stabilize the monofiber, cut bristles of the required length from the monofiber, unhook the bristles at the working ends along the boundary layers to a limited length under by the action of mechanical forces across the bristle axis. 5B The second method of obtaining bristles, as well as interdental cleaning elements from the indicated monofiber includes the following stages: at least two polymers are collectively extruded into a monofiber, after extrusion,

F) pulling and, if necessary, stabilizing the monofilament along the boundary layers for a limited length with the formation of short slits under the action of mechanical forces across the axis of the monofilament. According to the method according to the invention, it is possible to form crack-like slits in the sheath of the monofilament, which are used for receiving the working media. In the case of toothbrushes or interdental cleaning elements, these are usually toothpastes or dental or antibacterial preparations. As a result of splitting, the surface of the shell is characterized by increased roughness.

Interdental cleaning elements of arbitrary length can be obtained from the monofiber described above.

Naturally, the same can be done with bristles cut from monofilament. The position and length of the slots b5 can be adjusted according to the length of the bristles in order to prevent or facilitate the splitting of the end of the bristles, as required in the particular case. For example, you can unhook only the end of the bristles. The slits made in the shell can be used to further split the bristles after the wear flags have disappeared.

Depending on the nature and number of introduced layers, the corresponding number of flags is formed on the working end of the bristles.

To obtain interdental cleaning elements of arbitrary length from monofibers in accordance with one of the variants of the implementation of the method, crimping of the monofiber in the axial direction is provided during or after the action of mechanical forces on it. In this way, areas with longitudinal slits and strips limiting the slits, respectively, turn out to be convex.

Mostly, mechanical forces are applied around the circumference of monofiber or bristles to ensure action on 7/o All boundary layers of polymers.

Splitting of monofilament or bristles is mainly carried out under the action of impact forces. Instead of them, you can use crimping or twisting forces. These forces can be applied to the bristles being cut, or also to a group of bristles, such as bundles of bristles, before or after they are fixed in the brush handle.

The bristles are mostly rounded at their working ends. This can be done before or after splitting. 7/5 According to another preferred embodiment of the method, several ends obtained after splitting are provided with optical marking indicating the useful length. This shows the user that the bristles have worn down to the mark, meaning that once the split ends are gone, the wearability suddenly changes as a much stiffer section of the bristle core now comes into play.

Split ends are also getting shorter all the time and, accordingly, are becoming more and more irritating. Such a display is especially appropriate in the case of toothbrushes, hair brushes, etc.

Further, options for implementing the invention are described in detail with references to the attached drawings, which show:

Fig. 1 - 5 represent different cross-sections of monofiber. Fig. b - a view of bristles with a split working end.

Fig. 7 - a bristle or an interdental cleaning element with a slotted shell.

Fig. 8 - the second version of the section of the monofiber. high school

Fig. 9 - an alternative version of the interdental cleaning element.

Monofiber 1 in Fig. 1 has a circular cross-section and is obtained by the combined extrusion of at least two polymers. and)

It has a polymer matrix 2, which determines the properties of the bristles, and thin layers 3, included in a geometric shape, in this case cross-shaped, and which consist of a second polymer or its mixture with the matrix polymer 2.

Secondary adhesion forces, i.e., forces at right angles to the longitudinal component of the monofiber, are weakened in the areas (s«f z of thin layers З or at the boundaries of the matrix. In the presented version, the thin layers extend to the circular surface 4 of the monofiber, but they can also end at a short distance from her. -

The polymer of matrix 2 can be, in particular, polyamide (PA), but thin layers C have, for example, a mixture of PA/PP or PA/PE polymers.

In the variant presented in Fig. 2, thin layers C are included in the matrix in the form of a three-pointed star, and Fig. 3 shows monofiber 1 of a polygonal, namely triangular cross-section. In this version, thin layers are included, which pass from the center to the edges, coming from the corners of the polygon. Naturally, they can also end on the surfaces between the corners.

In the variant shown in Fig. 4, the matrix 2 of the monofilament 1 is extruded with the inclusion of one more polymer from among several possible in such a way that this polymer is completely included in the matrix. For example, these can be filamentous structures 5, which, after obtaining a bristle or its splitting or crevice formation, affect its bending behavior or the strength of the formed flags. . Fig. 5 shows a flat rectangular monofiber 1, in which thin layers C are included in the form of a lattice, and? so that a set of essentially rectangular flags can be obtained from such a monofilament. Finally, Fig. 8 shows the cross-section of a monofiber, in which the matrix 2 has four identical outer sections with a circular cross-section and a central core bordered by correspondingly located thin layers 3. c Fig. b schematically shows a bristle b obtained by cutting a monofiber, for example according to Fig. 2, to the required length, the working end of which is split under the action of mechanical forces to obtain separate flags

Ш- 7, the shape of which corresponds to the shape of the sections of the monofiber that make up the matrix 2. There are as many flags as the matrix 2 is divided into thin layers 3. The useful length of the flags can be optically marked with a transverse line, as shown in Fig. 6. - In the variant shown in Fig. 7, mechanical forces are applied to the circular surface of the monofiber at equal distances from the working end. By selecting the thickness of the layer and the amount of force and/or the frequency of its application, it is possible to ensure that the monofiber shell or bristle 6 is worn only on a limited section and that slots 8, 9, and 10 are formed. In this version, the slots are worn at the end of the bristle, which is accompanied by the formation of flags As the bristles wear, the shape of the flags constantly changes.

Monofilament according to Fig. 7 can be used as an interdental cleaning element ("dental silk")

F) segments of arbitrary length. Toothpaste, antiseptic or antibacterial preparation can be placed in the crevices. In the case of an interdental cleaning element, it is recommended to thicken along the axis of the monofilament, as shown in fig. 9, so that the strips of the matrix 10, in which the slots 9 are made, protrude outward in the appearance of protrusions.

In all the shown variants, the matrix polymer can be painted in different colors on different sections of the cross-section 2, separated by layers 3.

Claims (29)

The formula of the invention b5 1. A monofilament with weakened secondary adhesion forces of at least two polymers extruded in a regular geometric configuration, having marginal surfaces extending in a substantially axial direction, to produce bristles or interdental cleaning elements, which can be split in a substantially axial direction under action mechanical forces, which is distinguished by the fact that the edge surfaces are boundary layers in which the secondary adhesion forces are weakened, and the monofiber has a polymer matrix that determines the physical and chemical properties of the bristles and the interdental cleaning element, respectively, and the second polymer is included in the matrix in the form thin layers 2. Monofiber according to claim 1, which is characterized by the fact that the matrix has a copolymer or a mixture of polymers. 70 Z. Monofilament according to claims 1,2, which is characterized by the fact that the thin layers in the matrix have a copolymer or a mixture of polymers. 4. Monofiber according to claims 1, 2, which differs in that the polymer of thin layers forms part of the matrix polymer. 5. Monofiber according to claim 4, which differs in that the two polymers are present in thin layers in approximately equal 7/5 amounts. 6. Monofiber according to claims 1-5, which differs in that the thickness of the thin layers is several microns. 7. Monofiber according to claims 1-6, which is characterized by the fact that the thin layers in the matrix reach the circumferential surface of the monofiber. 8. Monofiber according to claims 1-6, which differs in that the thin layers in the matrix end at some distance from the circumferential surface of the monofiber. 9. Monofiber according to claims 1-8, which is characterized by the fact that the matrix of the monofiber has a third polymer included in the specified matrix. 10. Monofiber according to claims 1-9, which differs in that the polymers in the matrix and in thin layers have different colors. with 11. Monofiber according to claims 1-10, which differs in that the section of the monofiber is different from round. 12. Monofiber according to claim 11, which is characterized by the fact that the monofiber has a polygonal cross-section. and) 13. Monofilament according to claim 12, which is characterized by the fact that the thin layers reach the corners of the polygonal section. 14. Monofiber according to claim 12, which is characterized by the fact that the thin layers reach the surfaces of the polygonal section. "g zo 15. Monofiber according to claims 1-14, which differs in that the matrix has polyamide, and the thin layers - polyolefin. 16. The method of obtaining bristles from monofibers according to claims 1-15, which is characterized by the fact that at least two (87) polymers are collectively extruded into a monofiber, the monofiber is pulled out, if necessary, stabilized and cut into bristles of the required length, the bristles are split at the working ends across the axis of the bristle along the boundary layers for a limited length under the action of mechanical forces. 17. The method of obtaining bristles or interdental cleaning elements from monofibers according to claims 1-15, which is characterized by the fact that at least two polymers are collectively extruded into a monofiber, the specified monofiber is pulled out, if necessary, stabilized and split across the axis of the monofiber along the boundary layers for a limited length with formation of short slots under the action of mechanical forces. 18. The method according to claim 17, which is characterized by the fact that the monofiber is crimped in the axial direction during or after the action of 70 mechanical forces. from the village 19. The method according to claims 16-18, which is characterized by the fact that the mechanical forces act on most of the circumference of the monofiber or bristle. ;" 20. The method according to claims 16-19, which is characterized by the fact that the monofilament or bristle is split or cut by impact forces. 21. The method according to claims 16-19, which is characterized by the fact that the monofilament or bristle is split or cut with compressive forces. 22. The method according to claims 16-19, which is characterized by the fact that the monofiber or bristle is split or cut by s-twisting forces. Go! 23. The method according to claims 16-22, which differs in that before splitting, the working end of the bristles is rounded. - 24. The method according to claims 16-23, which differs in that after splitting, the working end of the bristles is rounded. her" 25. The method according to claims 16-24, which differs in that several flags of the bristle, obtained as a result of its splitting, at some distance are marked with a marking that optically shows the useful length. 26. A brush product having a handle and bristles attached to it, in which at least part of the bristles are made of monofiber according to claims 1-15 by the method according to claims 16-25. 27. The brush product according to claim 26, which is characterized by the fact that several ends of the split bristles have (Ф, marking indicating their useful length. ka 28. A brush product in the form of an interdental cleaning element, obtained from monofiber according to claims 1-17 by the method according to claims 19-20, which is characterized by the fact that the interdental cleaning element has slits at equal distances along the entire circumference. 29. Brush product according to claim 28, which is characterized in that the interdental cleaning element has bulges in the areas with slots. b5