Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Patent
1989-09-13
1991-09-03
Woo, Jay H.
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
264277, 264278, 425111, 425121, 425123, 425577, 425595, B29C 4514, B29C 4536
Patent
active
050452673
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a process and apparatus for producing bristle articles, comprising a bristle carrier of a mouldable or foamable material and plastic bristles anchored therein, with the bristles, in the form of single bristles or bristle strands, being inserted through channels and sleeves extending the same into a mould for the bristle carrier and being thermally melted at the end thereof located in the mould for forming a thickened portion, which is then sealingly engaged at the opening of the sleeve projecting into the mould, and with the mould being subsequently filled with the bristle carrier material.
Since the appearance of plastics, numerous attempts have been made to utilize the thermoplastic behavior of plastics for producing the connection or joint between bristles and bristle carriers. Thus, it was proposed in, for example (German Patent 355 645), to introduce the fixing ends of the bristles into a mould for the bristle carrier and to fill the cavity with a thermally plasticizable material.
This process was modified in, for example, (German Patent 895 140 in such a way that the same materials were used for the bristles and bristle carrier, namely polyamides or polyurethanes, so that at the elevated processing temperature a type of thermal fusion occurs between the two materials. However, this only makes it possible to produce bristle articles with the materialspecific characteristics of the particular material used and which are only able to meet specific use requirements. In addition, the specifically proposed materials are relatively high-grade plastics, which would lead to an unacceptable price increase for many bristle articles.
Nowadays bristle carriers are generally produced by a foaming or injection moulding process, which therefore immediately suggests itself for performing the aforementioned process. However, in injection moulding problems have occurred, because the liquid material injected into the mould penetrates between the bristle and between the bristles and the channels guiding them so that, after hardening, there is an undesired, irregular bristle-side sealing face on the bristle carrier. In the vicinity of its attachment to the bristle carrier, the bristle bundle also looses its elasticity and, as the penetration does not take place uniformly, in certain circumstances the different bristle bundles can have different bending characteristics. It is either impossible or only possible with great effort and expenditure to subsequently clean the attachment points.
Therefore numerous attempts have been made such as, for example, in DE-OS 29 22 877, to seal the guide channel for each bristle bundle, in that e.g. the injection moulding material is initially injected with limited pressure and prehardened on one mould wall and only then is the larger quantity of injection moulding material introduced into the mould. This process is extremely complicated if it is wished to obtain a completely satisfactory sealing face on the bristle carrier. In addition, for assisting rapid solidification of the material in the bristle attachment area, an intense cooling of the channels have been produced, which is impossible when the bristle bundles are closely juxtaposed. The proposal to produce a counterpressure to the injection moulding pressure in the guide channels is also not practicable, because this counterpressure leads to an irregular sealing face on the bristle carrier. The same applies with respect to the sealing of the openings of the guide channels prior to the injection moulding process and which are then opened after the pressure reduction in the mould and subsequently the bristle strands are then pressed into the still soft plastic material. This also impairs adhesion between the bristles and the bristle carrier material. The problem is also not solved by mechanical seals in the vicinity of the guide channels, e.g. as a result of a conical constriction of the opening or sealing lips located at this point, because it is not possible to pack the bristle
REFERENCES:
patent: 2643158 (1953-06-01), Baldanza
patent: 2666954 (1954-01-01), Potter
patent: 4106745 (1978-08-01), Carrow
patent: 4352772 (1982-10-01), Bezner
patent: 4609228 (1986-09-01), Bickel
patent: 4635313 (1987-01-01), Fassler
patent: 4637660 (1987-01-01), Weihrauch
patent: 4892698 (1990-01-01), Weihrauch
Coronet-Werke Heinrich Schlerf GmbH
Durkin II Jeremiah F.
Woo Jay H.
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