Brushing – scrubbing – and general cleaning – Implements – Brush or broom
Reexamination Certificate
2000-09-26
2002-07-02
Till, Terrence R. (Department: 1744)
Brushing, scrubbing, and general cleaning
Implements
Brush or broom
C015S167100, C015S207200, C300S021000
Reexamination Certificate
active
06412139
ABSTRACT:
PCT/EP99/04372. TRANSLATION OF APPLICATION AS FILED ON JUN. 24, 1999.
BACKGROUND OF THE INVENTION
The invention relates to a method for the manufacture of brushware having plastic bristles, which are continuously extruded as monofilaments, cut to the desired length and fixed individually or in groups as a bristle facing to a bristle carrier. The invention also relates to the brushware manufactured according to the method.
Brushware, such as tooth, massage, paint, textile and carpet brushes, but also numerous technical and industrial brushes, only fulfil their use function over a specific period of time, which is almost exclusively determined by wear to the bristles and is otherwise dependent on the nature of the brushware and the desired working result.
For example, brushes used in the personal hygiene sector have a relatively short use period and include massage, cosmetic and in particular toothbrushes. Therefore the fundamental problem of the invention will be illustrated in exemplified manner relative to toothbrushes.
Even in the last century it was recognized in connection with toothbrushes (U.S. Pat. No. 74,560 of 1868), that bristles which, at the time were exclusively made from animal hair, have sharp edges or seams as a result of cutting processes and which can lead to injuries to the gingiva. In order to remove such edges and seams, toothbrush bristles, but also bristles for other brushes used on the human body, are rounded at the use-side ends by mechanical abrasion. U.S. Pat. No. 74,560 proposes a conical abrading or grinding with a rounded tip.
In recent times toothbrushes have almost exclusively had plastic bristles, which are cut to the desired length from extruded monofilaments. The short cuts obtained in this way are generally combined into bundles, which are then fixed to the toothbrush head. It is still necessary to round the use-side ends, which still mainly takes place by grinding or abrading. In the final state, the bristle has an identical, cylindrical cross-section over its length and is rounded to a dome-shaped tip at its use-side end. Of late, conical abraded bristles are used, so that at least individual bristles of the bristle facing better penetrate the interdental spaces and can also effectively clean fissures on the tooth surface. However, the bristle must still have a rounded tip, in order to prevent injuries to the gingiva or also, as recent scientific investigations have revealed, brush lesions to the tooth. This more particularly applies in the case of sensitive gingiva or dental necks, which exist in almost 50% of users.
For the aforementioned reasons, bristles are already used in toothbrushes which are extruded from plastics monofilaments, but which are split to so-called flags at their use-side ends. In the lower, unsplit region of the bristle, use is made of the desired bristle bending capacity, whereas the flags permit a careful cleaning of the tooth surfaces and inter-dental spaces, as well as a careful massaging action for the gingiva. Similar combinatorial effects are obtained with brushes, which comprise a core and a sleeve or shell, which are generally made from different plastics by co-extrusion. The core mainly meets the strength requirements, whereas the sleeve is responsible for the cleaning and hygienic function.
When a toothbrush is in regular use relatively rapidly bristle wear arises and as a result the bristles lose their aforementioned characteristics. Wear more particularly starts on the bristle jacket, so that cylindrical bristles are tapered towards the bristle end and bristles with a conical end are pointed after a certain period of use. In both cases the round tip is worn away, usually in an irregular manner, so that the effects sought by the rounding are lost. In the case of bristles comprising a core and a sleeve, initially the sleeve is worn away in the vicinity of the bristle end and the core is exposed. In the case of bristles with flags, the wear progresses even faster due to the thin cross-sections of the flags. Since this leads to a constant decrease in the free length of the flags, conversely there is an undesired increase to their rigidity and there is a risk of the solid bristle stump causing injury.
For the aforementioned reasons dentists recommend the replacement of toothbrushes after a few weeks. The user frequently fails to do this, because it is impossible to optically perceive wear as a result of the limited bristle cross-sections, which are between 0.15 and 0.225 mm and even after a long period of use the toothbrush gives the optical appearance of still being usable.
Numerous attempts have been made to render visible to the user the degree of wear of a toothbrush. Thus, it is known (EP 366 100) to construct part of the toothbrush handle from a material which discolors or even dissolves as a result of use, so that in the first case it is rendered optically visible to the user and in the second through the non-usability of the handle that the toothbrush must be replaced. However, understandably, such a design is completely practically inappropriate.
According to another known proposal the bristle is made from a core and a jacket with a different color. As a result of the abrading action occurring on brushing, in the vicinity of the use-side ends the jacket is worn away and consequently the differently colored core material becomes visible, so that the user is made optically aware of the need to replace the toothbrush (DE 34 00 941, U.S. Pat. No. 4,802,255, 5,313,909, 5,268 005, WO94/10 539). Bristles of this type have already entered practical use, because no other appropriate solutions exist. However, the amount of wear is not apparent in a not with sufficiently high contrast manner to lead the user to replace the toothbrush at the correct time. The reproducibility of such a use indication is also inadequate. Frequently such an optical indication, only rendered visible by wear to the bristle, is only noticed at a late time or not at all. This method also presupposes a two-part bristle construction of core and sleeve.
This method fails in the case of modern bristle shapes, e.g. with a conical tapering bristle end, because either the jacket and therefore the entire bristle must have an excessive cross-section, or the core must be differently colored over its length, which is not technically possible by extrusion. This method also fails with bristles having flags or with brushes in which the use-side ends of the bristles are in a non-planar envelope or envelope surface.
The problem of the present invention is to continuously provide the brushware user with optical information concerning the existing use state and the degree of wear independently of the actual abrasion situation when using the brushware.
SUMMARY OF THE INVENTION
According to the invention, this problem is solved in that the monofilament after extrusion or the bristles produced therefrom is provided with at least one substantially linear boundary detectable on the bristle facing of the finished brushware as a color-contrasted marking, at a distance from the use-side end of the bristles representing the use state.
Thus, with the method according to the invention, the marking indicating the degree of use or the need to replace the brush is applied subsequently, namely after extrusion, to the monofilament or the cut-to-size bristle, in the form of a color-contrasted, linear boundary, which has a distance from the use-side end of the bristle representing the use state and therefore the degree of wear. This distance, i.e. the position of the boundary, can be fixed according to substantially objective criteria, in that the finished brushware undergoes a long-term or endurance test and the nature and extent of the wear is macroscopically investigated on the individual bristles. On the basis of the average values of the bristle wear of the entire bristle facing obtained in this way, it is possible to establish the particular bristle length, in which disadvantageous wear or abrasion phenomena for the correct function of the brush appear. Correspond
Coronet-Werke GmbH
Till Terrence R.
Vincent Paul
LandOfFree
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