WO2007104381A1 - Multi-filament bristles for toothbrushes - Google Patents

Abstract

The invention relates to a bristle (1; 4; 7; 10; 13), in particular for toothbrushes, and to a corresponding production method, wherein the bristle, in the longitudinal direction, has at least two jointly extruded filaments (2, 3; 5, 6; 8, 9; 11, 12; 14, 15) made of different materials, wherein the cross-sectional area of at least one of the filaments (3; 5; 9; 11) decreases toward the free end of the bristle.

Description

Designation: Multi-filament bristles for toothbrushes

description

The invention relates to bristles, in particular for toothbrushes, their production method and corresponding brushware, wherein the bristles in the longitudinal direction at least two jointly extruded filaments of different materials.

State of the art

Toothbrush bristles typically consist of polyester or nylon monofilaments, that is, plastic filaments which are extruded, drawn and fixed. Nylon bristles are flexible, easily deformable and especially water absorbent. They must therefore be designed relatively thick, so that given flexibility requirements can be achieved. This requires rounding the bristle ends to prevent injury to the gums.

In contrast, polyester bristles made of, for example, polybutylene terephthalate (PBT) and / or polyethylene terephthalate (PET) have a low water absorption rate and good durability properties. However, these bristles usually do not meet the requirements of elasticity or bending stiffness. They are typically too stiff and inflexible and can thus lead to damage to the gums.

In order to increase the flexibility of polyester bristles, EP 1 234 525 B1 discloses a process for the production of toothbrushes with highly conical bristles. Here, polyester monofilament bristles are immersed in corrosive chemicals until the immersed portion of the monofilaments is completely eroded. This eventually leads to a tapered bristle end.

It is disadvantageous in this case that the chemically sharpened ends of the bristle are attacked and subject to massive damage due to the etching process. The etching process thus produces a high reject rate which adversely affects the production costs. In addition, the tapered bristles made of a monofilament due to the eroded lateral surface have a low durability and an already too low flexural rigidity. Furthermore, the shape of the tapered bristles is essentially determined solely by the etching process and can not be designed according to predetermined requirements.

Furthermore, it is known from the prior art, for example from EP 1 030 937 B1, to produce bristles or interdental cleaners from a monofilament of at least two jointly extruded polymers. Here, for example, two polymers are coextruded into a monofilament and slit after a subsequent stretching and optionally stabilizing by the action of mechanical forces transverse to the monofilament axis to a locally limited length along the boundary layers between the polymers. As a result, fissure-like slots can be formed on the jacket of the monofilament, which can serve to accommodate media, in particular dentifrices or dental or antibacterial preparations.

To form fissure-like slits of a monofilament co-extruded from two polymers, the action of mechanical forces is always provided for splitting the monofilament along the boundary layers between the at least two polymers. The mechanical introduction of slots, columns and flags is complex on the one hand and relatively imprecise on the other hand, because the formation of such gaps depends essentially on the amplitude and the direction of the applied force and the binding forces between the polymers. The slots thus produced often have different and difficult to control lengths, irregular shapes and frayed lateral surfaces.

task

The present invention is therefore based on the object of providing tapered bristles, in particular for toothbrushes, with freely selectable geometry and improved elasticity properties. Furthermore, the invention has for its object to optimize a manufacturing or processing method for such bristles under production rational aspects.

Invention and advantageous effects

The object underlying the invention is achieved by means of a bristle according to claim 1 and a method for producing or processing such bristles according to Claim 11 and solved with brushware according to claim 17. Further advantageous embodiments of the invention are specified in the respective subclaims.

The bristle according to the invention has in the longitudinal direction at least two jointly extruded filaments of different materials and is characterized in that the cross-sectional area of at least one of the two filaments decreases towards the free end of the bristle. Thus, at least one of the at least two coextruded filaments changes its geometry in the region of the bristle end. It is crucial here that the two extruded filaments consist of different materials, such as polyester and polyamide, which can be subjected to a material-selective machining process to form the bristle according to the invention.

By selecting and arranging the different materials for the coextruded filaments of the bristle, both the flexurally elastic properties of the bristle and its geometric configuration, in particular in the region of the bristle ends, can be designed almost as desired.

According to a first embodiment, the cross-sectional area of the at least one filament steadily decreases toward the free end of the bristle. A steady decrease in the cross-sectional area is accompanied by a continuously decreasing lateral surface and a continuously decreasing diameter of this bristle filament. Sharp corners or edges, the characteristics of discontinuously extending lateral surfaces or surfaces are thus avoided in an advantageous manner. The risk of injury to sensitive areas within the oral cavity, such as the gums, can thus be lowered advantageously.

In another aspect, the cross-sectional area of the free end of the bristle is substantially determined by the at least one other filament. In a preferred embodiment, its cross-sectional area is substantially constant in the longitudinal direction of the bristles. In particular, it is provided that the at least one filament at the free end of the bristle has a cross-sectional area of zero, so that the total cross section of the bristle at the free end of the bristle is determined essentially by the remaining at least other filament.

By effectively reducing the cross-sectional area of the bristle ends, the entire bristle can better meet the given elasticity or bending stiffness requirements correspond. In contrast to a tapered monofilament produced by chemical etching, the bristle according to the invention is not chemically sharpened at its end of the filament and therefore also not attacked or otherwise damaged.

According to a particularly advantageous embodiment of the invention, the at least one other filament is at least partially radially enclosed by the at least one filament. In this case, provision is made in particular for the at least other filament to form a radially inner core section of the bristle, while the at least one filament surrounds this inner core filament as a sheathing. Towards the bristle end, this core sheathing finally tapers, until at the free end of the bristle only the other filament forming the bristle core remains and forms a tapered bristle cross section.

In particular, it is provided here that the at least other filament, e.g. the core filament is wider in the axial direction than the one filament, e.g. the sheath filament extends. The free end of the bristle is therefore formed only by that filament whose cross-sectional area does not change substantially.

It may further be provided that a plurality of filaments not changing in cross-section are regularly distributed over the cross-section of the bristle and are surrounded at least partially in the radial direction by the at least one filament whose cross-sectional area has a change towards the bristle end. By tapering the cross-sectional area of the at least one filament towards the free end of the bristle, a configuration can ultimately be formed at the bristle end that forms a plurality of individual filaments separated by gaps. Such fiian ment arrangements are for example for the inclusion of dentifrices or dental or antibacterial preparations of advantage.

According to a further embodiment it is provided that the at least other filament is rounded or rounded at its free end. The filaments forming the free end of the bristle thus have essentially no edges which could lead to injuries in the oral cavity.

According to a further embodiment of the invention, the at least two filaments have a different elasticity and / or a different bending stiffness. Depending on the proportion of filaments made of different materials in the total material of the Bristle, the elasticity and / or bending stiffness properties of the bristle can be adjusted specifically to a predetermined level.

It is further provided that the at least one filament can be removed by means of an etchant, in particular a chemical etchant, such as sodium hydroxide, sulfuric acid or formic acid, wherein the at least other filament is substantially resistant to the respective chemical etchant. By choosing different materials for the at least one and the at least other filaments and a suitable selection of a chemical etchant, the free end of the bristle can be processed material selectively using a chemical etching process. Furthermore, almost any elasticity properties of the bristle ends and correspondingly versatile bristle end geometries can be realized by any arrangement and geometry of individual filaments.

According to a further embodiment, polyamide and / or polyester is provided as material for the filaments. These materials have different elasticity and stiffness properties. Furthermore, only one of these materials is attacked by the chemicals intended for a chemical etching process, such as, for example, sodium hydroxide solution, sulfuric acid or formic acid, while the respective other material is substantially resistant to the chemical. Nylon, PA 6.6, PA 6.10 and PA 6.12 are particularly suitable as the polyamide, while the polyester is essentially PET and / or PBT.

According to a further independent aspect, the invention relates to a method for producing or processing bristles, in particular toothbrush bristles, which have in the longitudinal direction at least two jointly extruded filaments of different materials. The method is characterized in that at least one of the filaments in the region of the free end of the bristles is at least partially removed by means of a chemical etching process. The at least one other filament is essentially resistant to the chemical used in the chemical etching process and corrodes at most to a negligible extent in the chemical etching process.

According to a preferred embodiment of the method according to the invention, at least one filament which is substantially resistant to the etchant is exposed at least partially, preferably in the region of the free end, by means of the etching process. The parameters of the etching process, such as immersion depth of the bristle ends in the chemical and their residence time in the chemical are preferably determined by the shape and the geometry, in particular to the radial dimensions of the filaments adapted. In this way, the etching process can be optimized so that the at least one filament in the region of the free end of the bristle are completely removed, so that there at least the other filaments can be substantially exposed.

This is particularly important if the bristle core is formed by a resistant to the chemical used filament, which is radially enclosed by the corroded filaments in the etching process as a sheath. As a result of the etching process, therefore, the sheath of the multi-filament bristle surrounding the inner bristle core is removed in the chemical etching process in such a way that it tapers conically toward the bristle end. Consequently, only the bristle sheath tapers, while a bristle core that is chemically undamaged extends beyond the end of the bristle sheath.

Furthermore, the etching process is universally applicable to a variety of different arrangements of different filaments. For example, by means of the etching process, the free ends of a plurality of filaments, preferably arranged regularly and spaced from one another, can also be exposed. This ultimately allows even the cost-effective and chemical production of slots that can be used to hold media. Furthermore, the production of bristles with split, consisting of several individual filaments, use-side end on a chemical and therefore cost-effective way is possible.

According to another aspect, the bristle ends are rounded or rounded after the etching process by means of grinding.

According to a further, particularly advantageous aspect of the invention, the bristles are fixed before the etching process on a bristle carrier provided for the bristles, in particular on a toothbrush head. Thus, the bristles are already in front of the processing of the bristle end etching and grinding process at its predetermined position on the brush head and no longer need to be attached to the etching of this, which would be associated with a much higher cost, since the tapered at their ends formed bristles should be treated with greater care.

The fixation of the bristles on the bristle head prior to processing of the bristle ends in particular enables a simplified production of complicated Taftgeometrien of bristles on the bristle carrier. According to a further independent aspect, the invention therefore relates to bristles of any kind, but in particular to toothbrushes with a bristle carrier, on which the multi-filament and tapered bristles according to the invention are arranged.

embodiments

Other objects, advantages, features and advantageous features of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawings. All described and / or illustrated features in a meaningful combination form the subject matter of the present invention, also independent of the claims or their dependency.

Show it:

1 shows a cross section through a two-filament bristle in cross-section A-A,

FIG. 2 shows the double-filament bristle according to FIG. 1 in longitudinal section;

FIG. 3 shows a multi-filament bristle in cross section,

FIG. 4 shows a bristle with segmented filaments,

Figure 5 is a bristle with external filaments and

FIG. 6 shows a bristle end with a plurality of exposed filaments.

In FIGS. 1 and 2, a bristle 1, in particular the bristle of a toothbrush, is shown schematically in cross-section. The bristle 1 here consists of two filaments 2, 3 different material, which are extruded, stretched and fixed together. Here, the one filament 2 forms an inner core of the bristle 1, while the other filament 3 surrounds the inner filament 2 as a sheath. For example, the inner filament is made of polyamide, such as nylon, while the outer filament 3 is polyester. By immersing the free end of the bristle 1, for example in a corrosive for the bristle sheath 3 chemical, such as sodium hydroxide or sulfuric acid, the originally cylindrical shell 3 is removed material selectively, while the resistant to the chemical bristle core 2 compared to its (not shown) basic state unchanged Geometry preserves. The polyester filament 3 forming the bristle jacket is etched away by immersion in the chemical such that the jacket 3 of the bristle, before reaching the free end of the bristle, tapers conically with a cross-sectional area which steadily decreases toward the bristle end.

Compared with a previously known etching process with monofilaments, this material-selective etching process has the advantage that the inner core 2 of the bristle is in no way damaged by the etching process. This still has a required flexural rigidity and can be easily sharpened or rounded mechanically in subsequent process steps. Furthermore, due to the material-selective etching of the bristle end, it is ensured that a predetermined minimum thickness of the bristle end can not be undershot, so that the risk of breakage or uncontrolled break-off is reliably counteracted.

Furthermore, such a material-selective etching process is associated with a reduction of the material to be removed, so that overall a higher yield of the etching process can be achieved with corresponding cost advantages.

FIG. 3 shows a further exemplary embodiment of a multi-filament bristle 4. Here, a plurality of filaments 6, which consist of the same material, are arranged regularly and spaced apart, distributed over the cross-section of the bristle 4. The spaces between the filaments 6 are filled with the filament 5, which is removed by the chemical used in the etching process. By dipping such a bristle end into the corrosive chemical, the filament 5 can also be completely removed at the free end of the bristle, so that the individual filaments 6 remain with a smaller diameter, which are suitable for receiving material in the filament interspaces as well as for penetration into the smallest interdental spaces.

Finally, FIG. 4 shows a further embodiment of a bristle 7, which has segments of different filaments 8, 9 arranged radially symmetrically in cross section. In contrast to the exemplary embodiment according to FIG. 3, all the filaments 8, 9 extend in each case from the center of the bristle to the edge of the bristle. Here too, a corresponding During the etching process, individual filaments 8 or 9 at the free bristle end are removed in a targeted manner.

Figure 5 shows another example of a bristle end in which individual filaments 12 of one material are disposed adjacent and spaced apart at the periphery of the bristle while the other filament 11 fills the core region of the bristle. In this embodiment, it is provided in particular that the filament 11 is partially removed by the etching process, so that the individual bristle filaments 12 are at least partially exposed and thus form a spread-open end of the bristle 10.

Finally, FIG. 6 shows a schematic side view of a further bristle end 13, which has different filaments 14, 15, which are preferably detached from one another by means of a chemical etching process and thus form a fanned-out bristle end. Here, e.g. that the filaments 14, 15 consisting of different materials can be provided by means of a further, not explicitly shown filament, such as e.g. in the manner of the filament 11 shown in Figure 5, are first held together, which is finally removed in the etching process, so that ultimately the fan-like structure shown in Figure 6 is formed at the end of the bristle.

Claims

claims 1. bristle (1; 4; 7; 10; 13), in particular for toothbrushes, which in the longitudinal direction at least two jointly extruded filaments (2, 3; 5, 6; 8, 9; 11, 12; 14, 15) of different Materials, characterized in that the cross-sectional area of at least one filament (3; 5; 9; 11) decreases towards the free end of the bristle. A bristle according to claim 1, characterized in that the cross-sectional area of the at least one filament (3; 5; 9; 11) steadily decreases towards the free end of the bristle (1; 4; 7; 10; 13). A bristle according to claim 1 or 2, characterized in that the cross-sectional area of the at least other filament (2; 6; 8; 12) is substantially constant in the longitudinal direction of the bristle. 4. Bristle according to one of the preceding claims, characterized in that the bristle (1; 3; 7; 10; 13) tapers towards its free end, in particular conically or tapered, is formed. 5. Bristle according to one or more of the preceding claims, characterized in that the at least one other filament (2; 6; 8; 12) is at least partially radially enclosed by the at least one filament (3; 5; 9; 11). A bristle according to one or more of the preceding claims, characterized in that the at least one other filament (2; 6; 8; 12) extends further in the axial direction than the at least one filament (3; 5; 9; 11). 7. Bristle according to one or more of the preceding claims, characterized in that the at least other filament (2; 6; 8; 12) is rounded or rounded at its free end. 8. Bristle according to one or more of the preceding claims, characterized in that the at least two filaments (2, 3; 5, 6; 8, 9; 11, 12; 14, 15) have different elasticity and / or different flexural stiffness. point. 9. Bristle according to one or more of the preceding claims, characterized in that the at least one filament (3; 5; 9; 11) can be abraded by means of an etchant, against which the at least other filament (2; 6; 8; 12) in the Is essentially resistant. 10. Bristle according to one or more of the preceding claims, characterized in that the material used for the filaments (2, 3, 5, 6, 8, 9, 11, 12, 14, 15) is polyamide, in particular nylon, PA6.6, PA6.10, PA6.12 and / or polyester, in particular polyethylene terephthalate (PET) polybutylene terephthalate (PBT). 11. A process for producing or processing bristles (1; 4; 7; 10; 13), in particular toothbrush bristles, which in the longitudinal direction at least two jointly extruded filaments (2, 3; 5, 6; 8, 9; 11, 12; 14, 15) of different materials, characterized in that at least one of the filaments (3; 5; 9; 11) in the region of the free end of the bristles (1; 4; 7; 10; 13) by means of a chemical etching process at least partially is removed. 12. The method as claimed in claim 11, characterized in that at least one filament (2; 6; 8; 12) substantially resistant to the etchant is exposed at least in regions by means of the etching process. 13. The method according to any one of the preceding claims 11 or 12, characterized in that by means of the etching process, a coat of filaments (3; 5; 9; 11) enclosing the inner core of the bristle (1; 4; 7; 10) is removed at least in regions becomes. 14. The method according to one or more of the preceding claims 11 to 13, characterized in that by means of the etching process, the free ends of a plurality of regularly arranged filaments (6; 8; 12; 14, 15) are exposed. 15. The method according to one or more of the preceding claims 11 to 14, characterized in that the bristle ends are rounded or rounded after the etching process by means of grinding. 16. The method according to one or more of the preceding claims 11 to 15, characterized in that the bristles (1; 4; 7; 10; 13) are fixed to a bristle carrier provided for the bristles (1; 4; 7; 10; 13) prior to the etching process. 17. Brushware, in particular a toothbrush, with a bristle carrier, on which bristles (1; 4; 7; 10; 13) according to one or more of the preceding claims 1 to 10 are arranged.