Method of brush manufacture

A method of manufacturing brushes wherein two brush tapes which are formed of synthetic resinous material and incorporate a plurality of bristle filaments held together by a knitting operation or a weaving operation or by means of an extruded bead are arranged adjacent each other and held in this relationship by means of a bead of synthetic resinous material running along one side edge of the tapes. This bead may be extruded around the adjacent edges of the tapes or if beads of plastics material are already present on the tapes, may be formed by fusing the two beads together. There may be more than two adjacent tapes which may be arranged side-by-side or at an angle to each other or spaced apart and the construction of the tapes can be the same or different. Furthermore, one or more barrier layers may be located between the tapes. It is even envisaged that un-beaded tapes could be fused together, and the bead would then be formed by a forming operation.

This invention relates to a method of manufacturing brushes. 
In U.K. patent Specification No. 730131, a method of manufacturing brush 
strips is disclosed wherein an organic material is heated to plastic state 
and is extruded through a mouthpiece into a continuous U-shaped strip 
through a groove-shaped guide member, whereupon a plurality of aligned 
bristles are conveyed by means of an endless belt together with a thread 
of metal and are folded around a guide cam and led into the open topped 
guide member. The guide member has a tapering slot in its upper surface at 
the bristle feed-in location, and as the bristles are advanced and the 
U-shaped strip is pulled out of the guide member, so the bristles are 
folded with their ends upwards by the narrow slot, and pressed down into 
the U-shaped strip. In this way, the side walls of the U-shaped strip are 
pressed against the bristles which are partly pressed into the soft 
material of the strip and held therein. It is preferred that the strip is 
cooled on emergence from the extruder so that it maintains its shape 
better. 
Brush strips made in accordance with the above teachings are wholly 
unsatisfactory in that, due to the low temperature of the U-shaped strip, 
the bristles are only pressed into its surface and cannot even form a 
satisfactory mechanical key with the strip. This means that after a few 
uses, the bristles tend to fall out of the strip. 
In our U.S. Pat. No. 4,133,147, a method of manufacturing brush components 
is disclosed wherein a plurality of endless bristle filaments are folded 
into a zig-zag formation and held in that position by means of threads 
knitted into the zig-zag, the resultant tape then being slit centrally and 
having plastics locking beads extruded onto it either before or after 
slitting. 
In our subsequent co-pending U.S. patent Application Ser. No. 165,790, 
further methods of brush construction are disclosed wherein beads of 
plastics material are extruded onto aligned cut bristle elements held 
between endless haul-off belts. 
In our U.S. patent Application Ser. No. 165,789 we disclose a method of 
manufacturing brush components wherein a weft formed from a tow of endless 
bristle elements is woven with suitable warp yarns to provide a woven 
fabric which subsequently has plastics beads extruded onto it transverse 
to the tow wefts and is slit into brush component tapes. 
The various longitudinally extending knitted, cut bristle or woven brush 
components the subject of the above specifications but without their 
extruded plastics beads--either slit longitudinally so as to remove one 
edge, or unslit--will hereinafter be referred to as brush tapes as 
hereinbefore defined. The components which already have a bead on them 
will be referred to as beaded brush strips as hereinbefore defined. 
The present invention seeks to provide an improved method of manufacturing 
brushes, which method incorporates the use of brush tapes or beaded brush 
strips as hereinbefore defined. 
According to the present invention, we provide a method of manufacturing a 
brush component wherein at least two brush tapes having a plurality of 
aligned bristles are arranged adjacent each other and are held in this 
relationship by means of a bead of synthetic resinous material running 
along one side edge of the tapes, the said bead acting as an anchoring 
device for securing the brush component in a brush holder. 
In one construction, for example, if the tapes are knitted or woven tapes, 
the two tapes can be held in abutting side-by-side relationship and have 
the bead extruded along their abutting side edges by passing the tapes 
together through an extruder. However, instead of extruding a bead, it 
could be formed by passing the tapes through a fusion head. Alternatively, 
if the tapes are formed by different methods and/or already have beads 
along their side edges, then the existing beads along their side edges can 
be fused together to provide a single anchoring bead. 
If desired, several tapes may be arranged in side-by-side relationship and 
these may be of similar or of different construction. For example, the 
tapes may be formed of the same or different bristle components or they 
may be of different densities or thickness or the bristles or tows or 
bundles into which they are formed may be of different diameter. 
In order to strengthen the brush component, a carrier may be incorporated 
in the bead and this may be in the form of a coated or uncoated wire or 
textile filament. If a wire is provided, this will means that if the 
component is bent to a particular shape, it will maintain that shape. 
In a particular embodiment of this invention, one or more barrier layers, 
e.g. cloths or impervious membranes, may be incorporated into the 
component. The membrane can be a single sheet of plastics material located 
between the two tapes, e.g. a polymeric sheet which would fuse with the 
material of the bead, or, alternatively, a plurality of individual 
overlapping membranes could be provided. If desired, the membrane may be 
pre-formed into a generally pleated construction and by spacing the two 
brush tapes slightly apart, the pleated membrane can then be accommodated 
between the tapes. Obviously, the closer together the tapes are located, 
the more the bristles on each side of the tape will be accommodated in the 
indentations provided by the pleats. With such a construction, the 
resultant brush component would not lose any of its flexibility in the 
longitudinal direction and could be flexed easily about its bead, and if 
an impervious membrane is used, the brush could be largely waterproof. 
If desired, the two or more tapes making up the brush component could be 
orientated relative to each other so that instead of lying side-by-side, 
they are inclined to each other with only the edges of the tapes to which 
the bead is applied being adjacent each other. 
Alternatively, the tapes could be slightly spaced apart. 
In both these constructions, a membrane may also be provided between the 
tapes.

Referring to FIG. 1, two knitted brush tapes 1 (as disclosed in our U.S. 
Pat. No. 4,133,147) are fed in the direction of the arrow A into an 
extruder E, together with a strengthening wire 3 (this may be omitted), 
and are brought together; a bead 5 of synthetic resinous material is then 
extruded onto one pair of adjacent edge portions of the tapes 1. Either 
before or during the extrusion operation, the adjacent edge portions are 
heated to a temperature sufficient at least to soften them and preferably 
sufficient to fuse them together. On emerging from the extruder E, a 
cutter K slices the bottom looped edges off the tapes, whereupon the warps 
W from the knitted tapes are removed by pulling. 
In the construction shown in FIG. 2, two tapes 1, onto edge regions of 
which thermoplastics beads B have already been extruded, i.e. beaded brush 
strips as hereinbefore described, are brought together and fed into a 
fusion head F, and the two beads B are fused into a single bead B'. 
Thereupon the component is slit and the warps W are removed as before. 
The method shown in FIG. 3 is similar to that of FIG. 1, although in this 
case, a barrier fin 8, e.g. a thin film of the same thermoplastic material 
as the bristle in the tapes 1, is fed into the extruder (not shown), 
between the tapes 1, and is held in position by the extruded bead 5. 
The method shown in FIG. 4 is similar to that of FIG. 3, but in this case, 
the barrier fin is pleated, as shown at P. 
In the modified method of FIG. 5, a two-layer barrier fin is provided by 
two rows of sheets S of thermoplastic film, the sheets S being staggered 
so that the gaps in one row are covered by sheets S in the other row. 
In the embodiments of both FIGS. 4 and 5, the barrier fins are designed to 
provide maximum flexibility in the finished brush component. 
The construction shown in FIG. 6 differs from the others in that the brush 
tapes 1, instead of being located side by side, have one edge adjacent 
that of the other tape, but they are splayed outwardly, so as to be 
inclined with respect to one another at an acute angle of about 40.degree. 
(this can vary). As a result, a fatter bead 5a is extruded over the 
adjacent edges. 
The construction shown in FIG. 7 is similar to that shown in FIG. 1 (but 
without the wire 3), except that two different tapes 1 and 2 are used. The 
tape 2 is made of a bundle of bristles which is fatter than that of the 
tape 1, thus providing in the finished product different bristle 
characteristics. Furthermore, the tapes are spread apart, and a wide bead 
5b is therefore required. 
Likewise, in the construction of FIG. 8, two different tapes 1 and 4 are 
shown, the tape 4 being made by a weaving operation, as disclosed in our 
U.S. patent Application Ser. No. 165,789. 
Many different constructions have been described above and it will be 
appreciated that brush components can also be made in accordance with the 
invention by taking various different features of the different Figure 
embodiments and combining them. For example, a woven tape 4 could be 
combined with a tape 1 in the method of FIG. 1, or the wire 3 (which could 
be plastic coated) could be used in any of the methods of FIGS. 2-8. 
Likewise, one of the different barrier constructions could be used in any 
of the methods illustrated without a barrier or fin. Also, the tapes can 
be inclined in any of the constructions, as shown in FIG. 6, or one (or 
more) tapes 2 could be combined with a different tape (e.g. 1 or 4) in any 
of the constructions of FIGS. 1-6. 
It should also be borne in mind that where an extruder is used, the tapes 
will be heated, and the extruder is specially designed to soften the tapes 
prior to extrusion in the vicinity of the extruded beads. By choosing the 
correct material for the bristle filaments, and the correct temperature 
for the extruder, and by having the same material as the bristles for the 
extruded beads, it is possible to cause complete fusion between the 
bristle filament portions in the vicinity of the extrusion, and between 
said portions and the extruded bead itself. The fusion of the bristle 
filament portions can take place before or during the extrusion operation. 
It is also possible for two or more brush tapes to be fused together 
without an extrusion step by passing the tapes through a suitable heating 
device, and the molten tape portion can then be formed into a bead. 
In all the constructions, the extruded bead on the component is designed 
for location in a groove in a brush holder, and to lock the component into 
the groove, if necessary with an adhesive. This may not be necessary if 
the groove is re-entrant in cross-section.