Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2001-08-28
2004-04-27
Aftergut, Jeff H. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C300S002000, C300S004000, C300S008000, C300S021000
Reexamination Certificate
active
06726789
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a method for the production of brushes, consisting of a bristle support and bristles of at least two different bristle types which are fastened thereto and combined to at least one group having a defined cross-section by uniting the bristles of one bristle type to form a partial group and the partial groups forming the bristle group are combined in converging guides to form the bristle group, wherein the bristle group is subsequently attached to the bristle support. The invention also concerns a device for carrying out the method.
Conventional brushes consist of a bristle support and bristles fastened thereon which are usually combined to form bristle groups, e.g. bundles. The bristle groups are mounted to the bristle support either mechanically, using the so-called punching method, or, if the bristles and bristle supports are made from plastic, more recently using a thermal process, in optional combination with a mechanical deformation method. Such recent methods include welding of the bristles onto the surface of the bristle support, inserting the bristle bundles into a bristle support surface which is melted to a greater or lesser extent or injection molding the bundle by melting the bristle ends at the bundle foot to form an enlargement and extruding bristle support material around this area. These thermal methods have been used, in particular, for tooth brushes, hygiene brushes etc.
The selection of bristles with regard to material, cross-section and length depends largely on the intended use of the brush. The arrangement and number of bristles in a bundle, the arrangement and shape of the bundles themselves or of the bristles which are combined into groups vary in dependence on the intended use. The term brushes also includes brush-like devices for applying media, wherein the bristles are generally disposed in one group only, i.e. a bundle, a package or the like.
As has been known in the art for some time, tooth brushes having a straight cut brush stock, i.e. with all bristle ends disposed in one plane, do not satisfy dental hygienic requirements, since the curved as well as uneven tooth surfaces and the interdental spaces are not adequately cleaned. For these reasons, tooth brushes were developed having bristle ends lying in envelope surfaces contoured to a greater or lesser degree, by e.g. providing the bristle stock with a wavy cut. There are also conventional brushes which have the ends of bristles of an individual bundle disposed on a conical surface. All these measures are intended to assure that the bristles reach into the interdental spaces.
Dental medical evaluations of such tooth brushes have, however, shown that the tips of individual bundles or the apex of a wavy cut are unacceptably aggressive on the smooth tooth surfaces and leave grinding traces on the enamel. They can also lead to injury of the gum and gingiva which causes discomfort, especially with sensitive gums.
These disadvantageous consequences can be alleviated, but not eliminated, by a conventional tooth brush (WO 96/16571). Its bristle stock consists of individual bundles whose ends lie in a conical surface having the above mentioned aggressive tip. Moreover, each bundle contains individual bristles which are longer than the other bristles in the bundles and whose ends are disposed in one single plane. These individual bristles thereby slightly protrude past the bundled bristles. This configuration is intended to improve cleaning of the interdental spaces, since the individual bristles can more easily access such areas compared to conical bundles. These brushes are difficult to manufacture, since the individual bristles have to be drawn into the bundles in a separate processing step.
Macroscopic studies have shown that the tooth surfaces have fine cracks into which conventional bristles, due to their diameter, cannot enter and which are therefore not cleaned. Thinner, fiber-like bristles (DE 94 08 268 U1) which are wrapped in an enclosed envelope, with only the ends protruding past the wrapping, were proposed for cleaning and gentle treatment of the gums. These thin fibers fold down outside the wrapping envelope and have almost no effect. In addition, the sharp envelope edge increases the danger of injury to the gums and gingiva as well as possible damage to the tooth surface due to grinding traces. This conventional tooth brush is also very difficult to manufacture.
With tooth brushes and also with other brushes, such as paint brushes and the like, the bristle groups must be arranged in defined geometrical shapes and different types of bristles must be inserted into the bristle stock or individual bristle groups forming same to achieve the effects required for the respective application. DE 16 04 673 discloses bundles having differing cross-sectional shapes and DE 35 05 972 discloses combining the bristle stock of differently shaped bundles. These different bundle shapes are generated by rolling endless monofilaments to form a cord, wherein each cord consists of a number of monofilaments corresponding to the number of bristles in a bundle. The monofilament cord is pulled or pushed through a shaping device which forms the cord, of irregular cross-sectional shape, into the desired cross-sectional shape. Downstream of the shaping device, the bundles are cut to the desired length and fastened to the bristle support. This only allows variation of the bundle shape.
DE 196 16 309 suggests the production of bundles of bristles of different types by winding together endless monofilaments of various types to form a cord, from which individual bundles are cut. In this case, different types of bristles are present within the bundle in a static, uniform distribution. The various bristles are not distributed and arranged in dependence on the application. EP-A1-0 716 821 discloses tooth and body care brushes with which the bristles are collected into groups containing different kinds of bristles.
In conventional brushes having injection molded bundles (U.S. Pat. No. 5,728,408) the bristles, cut to bundle length, are removed from a magazine using punching tubes and inserted in bundle channels of an injection molding form and into the mold cavity. Several bundles of circular cross-section can thereby be combined via converging channels, next to one another, into stripe-shaped bristle groups having a width corresponding to the bundle diameter. Neighboring bundles may comprise various bristles disposed next to one another in the stripe-shaped bristle group. The various types of bristles thereby disadvantageously mix in the transition area between neighboring bundles and are not effective in this area. Since bristles of various types are adjacent to one another in the stripe-shaped bristle group and are used in the same manner during brushing, both types of brushes display differing signs of premature wear.
It is the underlying purpose of the invention to further develop the conventional method of U.S. Pat. No. 5,728,408 according to the preamble of claim 1 in such a manner that brushes can be produced in any form and in dependence on the intended use which have bristle groups consisting of partial groups of various cross-sections, with bristles of different types and different numbers in the partial groups.
SUMMARY OF THE INVENTION
This object is achieved in accordance with the invention in that the bristles of each partial group are shaped in a surrounding shaping device guide to obtain a cross-section corresponding to their partial cross-section in the bristle group and the partial groups are then combined in the guides to obtain the cross-sectional shape of the bristle group. Preferably, the bristle group is then transferred to a holding means to transport the bristle group for fastening to the bristle support. The finished bristle group can also be attached to the bristle support directly after shaping.
The method according to the invention permits production of a bristle group of defined cross-section from partial groups of various bristle types also having
Aftergut Jeff H.
Coronet-Werke GmbH
Kilkenny Todd J
Vincent Paul
LandOfFree
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