Note: Descriptions are shown in the official language in which they were submitted.
`~_ 1 1 3377 1 5 60557-3427D
This is a Division of our Co-pending Canadian Patent
Application No. 565,081 filed 26 April 1988.
The present invention relates to a method of laminating
that is useful in manufacturing brushes.
Background Art
Numerous structures have been described in the prior art
as possible replacements for the conventional structure of a paint
brush in which part or all of the structure is sufficiently
inexpensive that it can be considered disposable after a single or
a relatively few uses. Illustrative structures of this type are
described in United States Patents Nos. 2,265,274; 2,514,496;
3,094,729; 3,783,468; 3,874,021; and 4,155,139. No such known
structure has become widely used, however, and for the most part
the public continues to use conventional paint brushes of the type
comprising a plurality of bristles ("bristles" as used herein
includes filaments of polymeric material) having base end portions
positioned along the sides of an elongate felt center spacer and a
tubular ferrule typically of metal that receives the portions of
the bristles along the sides of the center spacer in one end
portion, has a resin such as epoxy poured into it to bond the
bristles and center spacer in place, and then receives a portion
of a handle, typically of wood or plastic in its other end portion
so that the ferrule fastens the handle to the bristles. Such
conventional paint brushes typically require a large amount of
hand labor for their assembly, which adds significantly to their
cost. Also, many lower cost conventional brushes incorporate
polymeric bristles (e.g., polyester or nylon) many of which are
made hollow to reduce their cost, and as a result will buckle more
2 1 3377 1 5 60557-3427D
easily than solid bristles and will draw paint or other coatings
into the bristles by capillary action that will not be removed
when the brush is cleaned; and some of which are made with other
than circular outer peripheries (e.g., generally triangular or
cross like cross sections) to enhance the ability of their end
portions to be flagged (i.e., split into smaller fibers) to
improve their paint holding and spreading ability, and as a result
have longitudinal recesses along their outer surfaces that have a
tendency to retain paint when the brush is cleaned. Such retained
paint in or on the bristles causes the bristles to loose some of
their flexibility so that the brush is not as effective during
reuse as it was when it was new.
Other types of brushes are manufactured by techniques
such as wrapping the central portions of tufts of bristles around
the central portions of staples and driving the staples into a
backing member at the bottoms of recesses from one of its surfaces
shaped so that walls defining the recesses position the bristles
with their distal ends projecting at generally a right angle to
the surface; or wrapping the central portions of bristles around a
rod along its length and crimping a metal strip to a generally U
cross sectional shape around those central portions and rod so
that the distal portions of the bristles project in generally the
same direction. Like the paint brush structures described above,
however, manufacturing such other types of brushes requires
working with individual bristles and require backings made from
either molded plastics or wood.
Disclosure of Invention
The present invention provides a method of laminating
1 3377 1 5
~ 3 60557-3427D
comprising the steps of: providing individual plies made of
chipboard and coated with adhesive that has been dried and is
activatable by the application of water or heat; exposing the
plies to atmospheric moisture; pressing the adhesive coated plies
together; and radiating the pressed adhesive coated plies with
radio frequency energy so that moisture in the chipboard is heated
and driven from the chipboard to soften the adhesive so that the
softened adhesive bonds the plies together.
A brush having a sufficiently inexpensive structure that
it could be considered disposable by many, can be manufactured by
a largely automated method, and can be made as a brush adapted for
applying paint or other architectural coatings that compares
favorably in its ability to apply quality finishes to more
expensive manually assembled conventional paint brushes with
polymeric bristles and provides solid bristles with no recesses
along their outer surfaces which can be easily and effectively
flagged.
The brush may comprise a plurality of similarly shaped
plies adhered together in face to face relationship to form a
laminate having a handle end portion adapted for manual
engagement, and an opposite head end portion; and a plurality of
rows of bristles, each row having a base end portion adhered
between a different pair of adjacent plies in the head end portion
of the laminate and having distal end portions projecting
outwardly from said head end portion, the distal end portions of
the rows of bristles extending generally in the same direction,
wherein the bristles in each of the rows of bristles are of
polymeric material oriented longitudinally of said bristles and
1 3377 1 5
~ 3a 60557-3427D
are a unitary film in said base end portion, while being separated
in said distal end portion.
Preferably, the laminates of several such brushes are
attached together at spaced locations along their edges to form a
single plate like structure and are disposed with the head end
portions of the laminates projecting in opposite directions; the
head end portions of the laminates projecting in each direction
being closely adjacent in side by side relationship, and the
handle end portions of laminates projecting in one of the
directions being interdigitated with the handle end portions of
laminates projecting in the other of the directions. The
laminates of .such brushes are separable by breaking the spaced
locations to separate individual ones of the brushes.
The method for forming brushes comprises the steps of:
(1) cutting (e.g., with a die) one or more sheets to form a
plurality of plies each having a handle end portion and an
opposite head end portion, the plies being attached together at
spaced locations in a single layer and being disposed with the
head end portions of the plies projecting in opposite directions,
the head end portions of the plies projecting in each direction
being closely adjacent in side by side relationship and having
generally aligned end surfaces, and the handle end portions of
plies projecting in one of the directions being interdigitated
with the handle end portions
_4_ 1 3377 1 5
of plies projecting in the other of the directions, (2)
forming a plurality of pieces of fibrilatable o~iented
polymeric film having generally uniform lengths in the
direction of orientation and including a first set o~ pieces
5 having a width transverse to the direction of orientation
generally corresponding to the total width of the head
portions projecting in one direction and a second set of
pieces having widths transverse to the direction of
orientation generally corresponding to the total width of
10 the head portions projecting in the other direction; (3)
adhering one piece of film from each set to each of certain
ones of the single layers with the end surfaces transverse
to the directlon of orientati`on and a minor end portion of
one of the pieces of film overlaying and adhered to the head
15 end portions of the plies projecting in one of the
directions to which it corresponds in width, and a minor end
portion of the other of the pieces of film overlaying and
adhered to the head end portions of the plies projecting in
the.other of the directions and with major end portions of
20 the pieces of film projecting from the head end portions in
opposite directions; (4) separating the major end portions
of the pieces of film adhered to the single layers into
individual bristles; and (5) laminating the single layers
together in aligned relationship with the min,or end portions
25 of the pieces of film laminated between the single layers to
form a plurality of the brushes. Such brushes intended for
applying paint or similar coatings such as varnish or stain
can additionally have their distal tip end positions flagged
(i.e., split into smaller ~ibers) and trimmed to produce a
30 desired overall shape for the ends of the bristles.
Preferably the step of forming pieces of film
comprises the steps of: (1) melting polymeric material
comprising in the range of about 25% to 75% polyester and in
the range of 75% to 25% polypropylene (preferably about 70%
35 polyester and 30% polypropylene~); (2) drawing a sheet of the
molten polymeric material between surfaces, at least one of
which surfaces is provided by a shaping blade that forms
_5_ 1 3377 1 5
longitudinally extending ridges along one side portion of
the sheet; (3) stretching the sheet (e.g., at a stretch
ratio in the range of about 2.5 to 1 to 4 to 1) in the
direction of the ridges to orient the film in a direction
S parallel to the ridges; and (4) cutting the pieces of
polymeric film from the sheet of polymeric material. The
portions of the sheet between the ridges provide break lines
which facilitate separating the bristles from the pieces of
film and the ridges provide rounded surfaces for one side of
10 the separated bristles; and the plies are preferably
laminated together so that the rounded surfaces of the
bristles form both outer surfaces of the rows of bristles
which provides a more conventional appearance for the brush.
The blend of polypropylene and polyester in the
15 film made as described above provides a matrix of polyester
with microfibers of polypropylene interspersed throughout.
Those microfibers are generally oriented in the direction of
the ridges due to shearing action in the shaping blade by
which the ridges are formed, and the stretching of the film
20 in the range of 2.5 to 1 to 4 to 1 indicated above further
aligns the microfibers and decreases their brittleness and
orients the film (e.g., stretching the film at a ratio of
less than 2.5 to 1 was found to produce film that had a
tendency to break during the separating step or when the
25 tips of the bristles were flagged (i.e., split into smaller
fibers), and it was difficult to stretch the film at a ratio
of more than 4 to 1 due to the presence of the polyester).
Thase microfibers both (1) act as tearing lines within the
film to enable the film to tear between the ridges during
30 the separating step, and (2) form very fine tip fibers when
tip portions of the bristles are flagged by high speed
impact at room temperature, since at that temperature the
relativeLy hrittL~ pQLyester; (which- ia n~t~ab3ve it~ g~ass
transition temperature and is thus brittle) will shatter
35 leaving the relatively flexible polypropylene microfibers
(which are above their glass transition temperature and-are
thus more ~lexible) in tact. Ridged film of 100 percent
1 33 77 1 5 60557-3427D
--6--
polypropylene has also been made using the method described
above and was oriented by stretching the film in,the
direction of the ridges at a ratio of about S to 1. The
bristles separated satisfactorily during the separating
5 step, however the bristles could not be flagged as well as
the bristles of the polypropylene and polyester blend, and
thus would be more suitable for use in brushes of a type
which do not require flagging (e.g., scrub brushes). Also,
many other polymers and blends of polymers are known to form
10 fibrillatable film that may be useful for making bristles in
brushes using the method described above.
As illustrated, the separating step can comprise
the steps of providing an anvil having a generally planar
support surface with a straight edge at least the length of
lS the major end portions of the pieces of film parallel to the
ridges; ~2) moving the pieces of film attached to the plies rJ
along the support surface in a direction at a right angle to
the ridges and to the straight edge and toward and over the
straight edge with the portion of the major end portion of
20 the piece of film on the anvil supported by the support
surface; and ~3) impacting and deflecting individual ridges
out of the plane of the support surface as they leave the
support surface to separate the film between the ridges and
thereby form the bristles.
Preferably the individual plies made of
chipboard have a coating of adhesive on one side that is
dried prior to the step of laminating and is activatable by
the application of moisture or heat; and the step of
laminating c~mprises the steps of ~1) exposing the plies to
30 atmospheric moisture (i.e., preferably conditions of at
least 20 percent or higher relative humidity at normal room
temperature such as 68 degrees Fahrenheit), ~2) pressing the
A~ciYe coate~ plies to~th~r; -a~d ~3~) Eadiati~g the
pressed adhesive coated plies with radio frequency energy so
that moisture in the chipboard is heated and driven from the
chipboard to soften the adhesive so that the softened
adhesive bonds the plies together.
1 33 77 1 5
7 60557-3427D
Brief Description of Drawing
The present invention will be further described
with reference to the accompanying drawing wherein like
reference numerals refer to like parts in the several views,
5 and wherein:
Figure 1 is a perspective view of a brush that can
be made by the method of the present invention;
Figure 2 is an enlarged fragmentary edge view of
the brush of Figure l;
Figure 3 is a horizontal top view of five of the
brushes shown in Figure 1 attached together in a composite;
Figure 4 is a vertical side view of the composite
of five attached brushes shown in Figure 3;
Figure S is a reduced perspective view
lS illustrating a user separating one of the brushes from the
co~posite shown in Figure 3;
Figures 6, 7A and 7B schematically and
sequentially illustrate, with side and plan views, a method
-according to the present invention for making the brush
20 shown in Figure 1 in the composite shown in Figure 3;
Figures 8A and 8B are schematic side views of the
portions of the method according to the present invention
shown in Figures 7A and 7B, respectively;
Figure 9 is an enlarged fragmentary view taken
25 approximately along line 9-9 of Figure 6; and
Figure 10 is an enlarged fragmentary perspective
view taken approximately along line 10-10 of Figure 7A.
Detailed Description
Reerring now to Figures 1 and 2 of the drawing,
there is shown a inexpensive brush according to the present
invention, generally designated by the reference numeral 10,
which is particularly adapted for applying paint and other
architectural coatings.
Generally, as is best seen in Figure 2, the brush
10 comprises a plurality of similarly shaped plies 12 (e.g.,
1 33 77 1 5
--8--
of chipboard) adhered together in face to face relationship
to form a laminate 14, which laminate 14 has a h,an~le end
portion 16 adapted for manual engagement, and an opposite
head end portion 18; and a plurality of rows 20 of bristles,
5 each row 20 having a base end portion 24 adhered between a
different pair of adjacent plies 12 in the head end portion
18 of the laminate 14 and having distal end portions 26
projecting generally in the same direction outwardly from
the head end portion 18 which have tip portions 27 that are
10 flagged and shaped to help the bristles retain and apply
paint or similar coatings.
Preferably, the bristles in each of the rows 20 of
bristles are a blend of polypropylene and polyester, and
because of the method for manufacturing the brush 10
15 described below, while the distal end portion 26 the
bristles in each of the rows 20 are separated, those
bristles are joined together in side by side relationship in
the base end end portion 24 of each row 20, which provides
an extremely orderly array of bristles in the brush 10, and
20 restricts pulling individual bristles from the laminate 14.
As illu~trated in Figures 3, 4 and 5, the brush 10
is preferably manufactured in a composite 28 consisting of a
plurality of (e.g.,five as illustrated) attached brushes 10
each having the structure described above with the laminates
25 14 of the brushes 10 being attached together at spaced
locations 32 to form a single plate like structure 30 and
being disposed with the head end portions 18 of the
laminates 14 projecting in opposite directions; the head end
portions 18 of the laminates 14 projecting in each direction
30 being closely adjacent in side by side and edge to edge
relationship, and the handle end portions 16 of laminates 14
projecting in one of the directions being interdigitated
with the handLe end ~or~tions 16 Q~ La~inAt~ L4 proiPrting
in the other of the directions. The laminates 14 are
35 separable as illustrated in Figure S by breaking the spaced
locations 32 to separate individual ones of the brushes 10
from the composite 28.
1 33771 5
g
A method for forming the brush 10 according to the
present invention by forming the composite 28 i~
schematically illustrated in Figures 6 through 10. That
method generally comprises the steps of (1) cutting (e.g.,
5 with a die, not shown) one or more sheets to form a
plurality of the plies 12 (Figures 7A and 8A) each having a
handle end portion 36 and an opposite head end portion 38,
the plies 12 being attached together at spaced locations 39
in a single layer 40 and being disposed with the head end
10 portions 38 of the plies 12 projecting in opposite
directions, the head end portions 38 of the plies 12
projecting in each direction being closely ad~acent in side
by side relationship and having generally aligned end
surfaces 42, and the handle end portions 36 of plies 12
15 projecting in one of the directions being interdigitated
with the handle end portions 36 of plies 12 projecting in
the other of the directions; (2) forming a plurality of
pieces of oriented polymeric film (e.g., with the apparatus
43 illustrated in Figure 6, later to be explained) having
20 generally uniform lengths in the direction of orientation
and including a first set of pieces 44 having a width
transverse to the direction of orientation generally
corre~ponding to the total width of the head portions 38
projecting in one direction and a second set of pieces 45
25 having widths transverse to the direction of orientation
generally corresponding to the total width of the head
portions 38 projecting in the other direction; (3) adhering
one piece of the film from each set of pieces 44, 45 to each
of certain ones of the single layers 40 (e.g., by using hot
30 melt adhesive applied through a nozzle 47 as shown in
Figures 7A and 8A) with a minor end portion 46 of one of the
pieces 44, 45 of oriented film overlaying and adhered to the
head en~ porti~ans 3~ of the p~l-ies 12 ~u}~-Lir~g in ane~ of
the directions to which it corresponds in width, and a minor
35 end portion 46 of the other of the pieces 44, 45 of film
overlaying and adhered to the head end portions 38 of the
plies 12 projecting in the other of the directions and with
1 33 7 7 1 5
--10--
the major end portions 48 of the pieces 44, 45 of film
projecting from the head end oortions 38 in opposite
directions; (4) separatin~ the major end portions 48 of the
pieces 44, 45 of film adhered to the single layers 40 into
5 individual bristles (e.g., with mechanisms 50 of the type
shown in Figures 7A and 8A and best illustrated in Figure
10, later to be described) so that widths of the pieces 44,
45 of film form the base and distal end portions 24 and 26
for the bristles of the individual brushes 10 Figure 2); and
10 (S) laminating the single layers 40 together in a press 52
(Figures 7B and 8B) using the novel method described below
with the minor end portions 46 of the pieces 44, 45 of film
adhered to some of the single layers 40 laminated between
the single layers 40 to form the composite 28 including a
15 plurality of the brushes 10 each having the structure
described above and being separable by breaking the spaced
locations 32 to separate individual ones of the brushes 10.
As can best be seen in Figure 2, the lamination is
preferably done with two central layers 40 or plies 12
20 disposed with their surfaces opposite thei,r surfaces to
which the minor end portions 46 or base end portions 24 are
adhered in contact, several layers 40 or plies 12 to which
' the minor end portions 46 or base end portions 24 are
adhered on each side of those two central layers 40 or plies
25 12 (e.g., as illustrated, four on each side of the central
two for a total of ten layers 40 or plies 12 to which minor
end portions 46 or base end portions 24 are adhered), and
two layers 40 or plies 12 to which no bristles are adhered
before lamination forming the major outer surfaces of the
30 composite 28 or laminate 14. These outer layers 40 may have
words or pictures printed on their outer surfaces to
provide, for example, information concerning the
manufac~tu~rer of the~ b~u~l~s l~ ~r ir~-Lru~Lians for the~
separation and use of the brushes 10.
Preferably the step of forming pieces of film 44,
45 uses the apparatus 43 illustrated in Figure 6 and 9 and
1 33 77 1 5
comprises the steps of (1) melting polymeric material
comprising in the range of 75% to 25% polyesterland in the
range of 25% to 75% polypropylene in an extruder (not shown)
and expelling the melted polymeric material through a slot
S die 55 onto the polished surface of a cooled roller 56; (2)
drawing a sheet 58 of the molten polymeric material between
the surface of the roller 56 and a surface provided by a
toothed shaping blade 60 that forms longitudinally extending
arcuate ridges 62 along one side portion of the sheet 58;
(3) stretching the sheet 58 (e.g., at a stretch ratio
between about 2.5 to 1 and 4 to 1) in the direction of the
ridges 62 as by passing it in serpentine fashion first
around a set of heated rolls 64 to re-heat it, and then
around a set ~f pulling rollers 66 rotating faster than the
15 set of heated rollers 64 so that the sheet 58 is pulled
between the sets of rollers 64 and 66 to orient the sheet
58; and ~4) cutting the pieces 44, 45 of oriented polymeric
film from the sheet 58 of polymeric material as with a
cutter 68. Thin portions of the sheet 58 between the ridges
20 62 provide break lines between the ridges 62 to facilitate
separating the bristles from the pieces 44, 45 of polymeric
film and the ridges 62 provide rounded surfaces for one side
of the bristles. Preferably the layers 40 or plies 12 are
then laminated together so that the arcuate or rounded
25 surfaces of the bristles form both outer surfaces of the
rows 20 of bristles which provides a more conventional
appearance for the brush.
Preferably the separating step uses two of the
mechanisms 50 best seen in Figure 10, and comprises the
30 steps of (1) providing an anvil 70 having a support surface
72 with a straight edge 74 at least the length of the major
end portions 48 of the pieces 44, 45 of oriented film
paraIlel to the ridges 62; (Z)` moving the pieces 44, 45 af
oriented film attached to the layers 40 along the support
3s surface 72 in a direction at a right angle to the ridges 62
and to the straight edge 74 and toward and over the straight
edge 74 with the portion of t,he major end portion 48 of the
piece 44 or 45 of film on the anvil 70 supported by the
1 33 7 7 1 5
-12-
support surface 72; and (3) impacting and deflecting
individual ones of the ridges 62 out of the planR of the
support surface 72 as they leave the support surface 72 to
separate the major end portion 48 of the piece 44 or 45 of
5 film between the ridges 62 and thereby form the bristles.
Such impacting can be done as illustrated with a rotating
blade wheel 78 comprising a plurality of radially extending
evenly circumferentially spaced blades 79 having sufficient
widths axially of the blade wheel 78 to restrict axial
10 deflection (e.g., 0.32 centimeter or 1/8 inch), which blade
wheel 78 is rotated about an axis oriented at about a right
angle to the straight edge 74 and is located with respect
thereto so that the blades 79 will sequentially move through
a position at which their leading edges are about aligned
15 with the support surface 72, are parallel to and spaced less
than the width of one of the bristles (e.g., 0.010 to 0.025
centimeter or 0.004 to 0.010 inch) from the straight edge
74, and project along the straight edge 74 almost to the end
thereof along which the layer 40 is moved. The movement of
~20 the major end portions 48 over the straight edge 74 and the
rate of rotation of the blade wheel 78 are timed so that
each of the ridges 62 will be impacted by one of the blades
79 to be sure that each of the ridges 62 is separated into a
bristle.
Preferably the individual plies 12 are made of
chipboard and are coated on one side with water softenable
polyvinyl alcohol adhesive which is dried prior to
lamination ~Such adhesive coating and the die cutting of the
individual plies 12 can be done on conventional equipment
30 typically found in printing shops); and the step of
laminating comprises the steps of (1) exposing the plies to
atmospheric moisture (preferably conditions of at least 20
percent or higher relative humidity at normal room
temperature, although exposures to lower relative humidities
35 will work if more time is allowed for the radiating step);
(2) pressing the adhesive coated plies together as with the
press 52; and (3) radiating the pressed adhesive coated
1 3377 1 5
-13-
plies with radio frequency energy from a radio frequency
generator 80 (e.g., 30 megahertz frequency) so bhat moisture
in the chipboard is heated and driven from the chipboard
into the adhesive (presumably through the uncoated surface
5 of the chipboard into the contacting adhesive surface) to
soften it so that the softened adhesive bonds the plies 12
together. Alternatively the individual plies 12 can be made
of chipboard and coated on one side with a hot melt adhesive
which is dried prior to laminat~ion and the step of
10 laminating can comprise the steps of (1) exposing the plies
to atmospheric moisture; (2) pressing the adhesive coated
plies together as with the press 5~; and (3) radiating the
pressed adhesive coated plies with radio frequency energy
from a radio frequency generator 80 (e.g., 30 megahertz
15 frequency) so that moisture in the chipboard is heated and
driven from the chipboard (presumably through the uncoated
surface of the chipboard into the contacting adhesive
surface) to soften the adhesive so that the softened
adhesive bonds the heated plies 12 together.
The method according to the present invention may
further include the known brush making step of flagging the
distal tip end portions 27 of the bristles to split them
into many smaller fibers and thereby improve the ability of
the bristles to spread paint and similar coatings very
25 smoothly and evenly onto a surface. This step may be
performed ~as illustrated) by a commercially available
flagging device 82 comprising cylindrically disposed
forwardly hooked knives rotated at high speeds (e.g., 7000
to 8000 rpm) against the distal tip end portions 27 of the
30 bristles after the laminating step so that the distal tip
end portions 27 of all of the bristles in the brushes 10 are
fla'gged in one pass. Alternatively this step may be
performed just after the bristles are separated on each
piece 44 or 45 of oriented film either with the flagging
35 device 82, or by the novel method of impacting the distal
tip end portions 27 of the bristles with the end portions of
monofilaments (not shown), the other ends of which
-14- 13377~5
monofilaments are fastened to a rotating drum. Successful
flagging by this latter method is more dependent on the
percentages of polyester and polypropylene in the bristles
than is flagging using the device 82, with 50% of each
5 providing very acceptable results.
The profile of the distal tip end portions 27 of
the bristles may be shaped so that, as illustrated, they are
tapered from both sides toward the center of the brush 10.
This can be done either by a novel method of cutting the
10 major end portions 48 of the pieces 44 or 45 of film adhered
to single layers 40 to different increasing lengths starting
with the the single layers 40 to be positioned adjacent the
outer surface of the plate like structure 30 toward the
single layers 40 to be used toward the center of the plate
15 like structure 30, or by the known chiseling methods of
trimming the distal end portions of the bristles of the
brush 10 to a desired shape after the plate like structure
30 is formed through the use either of a shaped
reciprocating cutter (not shown) similar to a barbers
20 trimmer or a high speed rotary cutting head.
Also the bristles are preferably cleaned to remove
broken or unbounded bristles either after the separating
step or after the laminating step by combing through the
bristles with wire carding cloth (not shown) and collecting
25 the removed bristles through the use of a vacuum system 86.
A rotating beater bar (not shown) can also be used in
conjunction with the vacuum system 86 to remove broken or
unbonded bristles and/or particles caused during separating
and flagging of the bristles.
Example
As a preferred non limiting example, the brush 10
was.made by forming film of a blend of about 30% by weight
polypropylene with a melt flow index of 12, about 70%
35 polyester by weight with an intrinsic viscosity of 0.6, and
about 0.1% sodium oleate by weight as a surfactant. As
described above, the blend was melted in and discharged from
-15- 1337715
the extruder, the molten polymeric material was drawn in a
sheet 58 between surfaces including the polished cooled
surface of the roll 56 and the toothed shaping blade 60
which had arcuate grooves between its teeth that formed
5 ridges 62 on the sheet 58 so that the sheet 58 had a
thickness of about 0.013 to 0.018 centlmeter ~0.005 to 0.007
inch) at the base of the grooves between the ridges 62, a
distance of about 0.048 centimeter (0.019 inch) between the
peaks of the ridges 62, and a thickness of about 0.061 to
10 0.069 centimeter (0.024 to 0.027 inch) at the peaks of the
ridges 62. The sheet 58 thus produced was stretched in the
direction of the ridges 62 at a ratio of about 3 1/2 to 1
which changed the sheet 58 so that it had a thickness of
about 0.003 to 0.005 centimeter (0.001 to 0.002 inch) at the
15 base of the grooves between the ridges 62, a distance of
about 0.038 to 0.046 centimeter ~0.015 to 0.018 inch)
between the peaks of the ridges 62, and a thickness of about
0.030 to 0.038 centimeter (0.012 to 0.015 inch) at the peaks
of the ridges 62. Sheets of chipboard (i.e., 50% virgin
20 kraft paper and 50% recycled newsprint) 0.02 inch thick and
coated on one side with 18.3 grams per square meter of
polyvinyl alcohol adhesive (e.g., that adhesive sold under
the trade designation ~3-3450 by H.B. Fuller Company, St
Paul, Minn.) that had been dried were die cut to form the
25 plies 12. These materials were used to form the composite 28
of brushes 10 in the preferred manner described above using
twelve plles 12 and 10 rows 20 of bristles disposed as shown
in Figure 2 for each brush 10 (the outer plies 12 not having
rows 20 of bristles adhered to them prior to lamination)
30 which were pressed together at about 60 pounds per square
inch and exposed to radio frequency of 30 megahertz for
about 30 seconds from a transmitter having an estimated 4
kilowatts af power to complete the lamination. E~ach brush
10 was then flagged, shaped and cleaned. The brushes 10
35 were found to pick up a reasonable quantity of paint when
dipped into the palnt; to release a reasonable portion of
the paint picked up on a surface being painted; and to
1 33 77 1 5
-16-
provide a fairly thick uniform paint coating on that
surface, with these qualities of the brush 10 being at least
equal to such qualities of many brushes with synthetic
bristles currently available in the marketplace which cost
S in the range of about one to two dollars.
The brush 10 and method for making the brush
according to the present invention have now been described
with reference to single embodiments thereof. It will be
apparent to those skilled in the art that many changes can
10 be made in the embodiments described without departing from
the scope of the present invention. For example, the novel
- bristles made by the novel method described above may be
useful in other brush structures having handle assemblies
other than thè laminate 14 described. Thus the scope of the
15 present invention should not be limited to the structure and
method descried in this application, but only by structures
described by the language of the claims and the equivalents
of those structures.
