Brush – broom – and mop making – Processes
Patent
1996-08-30
1998-10-20
Till, Terrence
Brush, broom, and mop making
Processes
151911, 300 8, A46B 304
Patent
active
058236333
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for manufacturing brushware and brushware.
2. Description of Prior Art
Ever since the first use of plastics both for the bristles and also the bristle carriers of brushware, numerous attempts have been made to replace the previous mechanical fixing of the bristle bundles to the bristle carrier by a positive or integral connection without any further mechanical fixing means. These more particularly include injecting in, in which the bundle ends are embedded by injecting round with the plastic melt for the bristle carrier and are fixed to the latter.
An essential quality feature of brushware is the extraction resistance of the individual bristles or bundles, i.e. the bristles must be so embedded in the plastic mass of the bristle carrier that they are not detached under the forces occurring during use. Among the known injection moulding processes only those have proved usable in which there is a thickening on the bundle ends located in the mould and which after injecting with the plastic mass of the bristle carrier forms a type of anchor and also interconnects the bristles at their fixing-side end, so that the extraction forces acting on the bundle or only on certain individual bristles are introduced into the thickening and absorbed by the fixing thereof in the bristle carrier.
The known processes use all injection moulds in which one mould half is provided with a number of channels corresponding to the bristle coverage and through which the bristle bundles can be supplied to such an extent that the ends of the bundles project into the mould cavity. The bristle ends of the bundle are then either interconnected by an adhesive forming a thickening (FR-A-1,453,829/Piotrowski) or, to the extent that they are formed from plastic monofilaments, are melted, the melt solidifying to a thickening having a larger cross-section than the bundle (DE 845,933/Schiffer).
It is obvious that the extraction resistance of the bristles increases the greater the embedding length of the bundle in the bristle carrier. However, this is countered by the following requirements. Both in the case of bristles, which are generally made from higher-grade plastics such as polyamides and for the bristle carrier the amount of material used must be kept as low as possible, which is to be implemented by a correspondingly short fixing or clamping of the bristles. Brushware also exists where the bristle carrier, for use reasons, must have a minimum wall thickness. This e.g. applies in the case of toothbrushes, so that due to the constricted conditions in the mouth a short construction, including the bristle length, is ensured.
In one known process (EP 142,885/Anchor) the bristle fixing length is minimized in that the thickenings obtained by the melting of the bristle ends as a result of the injection pressure during the injection of the plastic melt of the bristle carrier are displaced to the opening of the channel carrying the bundle, so that the fixing length is reduced to the thickness of the thickening and the anchoring of the bundle is exclusively achieved by the plastic mass of the bristle carrier penetrating into the narrow gap between the thickening and the mould wall. The further aim of this known process is to seal the channel by means of the thickening to prevent the injected plastic melt from passing out at the edge of the bundle or between the bristles (overspraying) and giving rise to burrs on the finished brush or at least to an unattractive appearance. This would also influence in an irregular manner the bending behavior of the bristles in the attachment area to the bristle carrier. However, this process is unsatisfactory for several reasons. Firstly the pressing of the thickening on the bundle channel is not certain and cannot be guaranteed in a reproducible manner. Thus, as a function of the guidance of the injection moulding material within the mould and as a function of the cross-section of the thickening, particularly its project
REFERENCES:
patent: 4635313 (1987-01-01), Fassler et al.
patent: 4892698 (1990-01-01), Weirauch
patent: 5458400 (1995-10-01), Meyer
Coronet-Werk GmbH
Till Terrence
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