Note: Descriptions are shown in the official language in which they were submitted.
Wo95/05101 ~ 6~5 51 PCT~S91,~922fi
NONWOVEN ~T~NTNG BRU8H
Technic~l Fiel~
The present invention relates to a nonwoven
thermally bonded fiber compressed brush construction
suitable for use in caustic mill environments such as
in steel strip mills, for example. More specifically,
the invention relates to a brush for use in caustic
10 environments wherein the brush is made from a plurality
of compressed annular sections made of bicomponent
nonwoven fibers. The brushes of the present invention
are made of fibers that can withstand extremely caustic
environments without requiring resinous coatings,
15 binders or the like.
Background Art
Prior to electrolytic tin plating, steel strip
20 must be thoroughly cleaned. This is done on a
continuous basis in steel strip mills by passing the
strip through a hot caustic cleaning tank and then
through hot water rinse tanks. Brushes are commonly
used in the cleaning process to agitate the surfaces of
25 the steel strip.
Historically, the aforementioned brushes have been
made from any of a variety of materials. Until
recently, bristled brushes were commonly used in the
cleaning process and typically had natural vegetable
30 fiber bristles. For example, brushes having tampico
bristles made from a coarse grass-like plant grown in
the region around Tampico, Mexico (hereinafter "tampico
bristled brushes") had enjoyed widespread use in steel
strip cleaning applications. Bristled brushes may also
35 include bristles of a synthetic construction such as
polypropylene, for example. Bristled brushes, however,
--1
.. " ~
~ 2168557
-
experienced a short service life in the cau~stic en~ironment of steel stri~
mills.
About ten years ago, a cleaning brush made of a compressed b~
formed of a multiplicity of ganged 5 segments ol n~lon non~voven ~eb fabri(
S was developed and sold in Australia b~ the,assigllee's subsidiar)~ com~a~
3M Australia. These brushes ~vere found to ha\ e all e~fective ser~ ice life t~ o
to three times that of the tampico bristled brushes. The Australian brush i~
made from an air laid randomly formed ~veb oF 1~ to 1~ denier n~lon staF~le of
length 38 millimeters. The nylon ~eb is needlelacl;ed to increase its dell~it
10 and strength, and the ~veb is thoroughl~ impregtlated vith a phellolic resi
solution as a binder ~vhich, vhen cured, ~r~j~ ides Ihe ~veb vith som~
resistance to highly caustic conditions This t\pe of brush constructioll h;
been utilized for about the last ten ~ ears~ ,
Ho~ever, the phenolic bonded n~loll ~eb brush has also e~hibil~:d
15 some shortcomings in the caustic~ en~ ironmellts in ~vhich it has been used
Although it generally enjoyed a much longer useful life than the tam~
bristled brushes, the nylon ~veb brushes arc ~;no-~ n to degrade and gener.l~
aste or "flufP' as a result of the gradual bre;ll;do-~n under hot causlic
conditions [typically pH 13 and #O C) of the F~rotecti~e phenolic resin bin-l-r
~0 coating the nylon fibers. The lluff is caused b) the release of the n~lon
staple fibers. The generation Or fluff is problem;ltic because it is diflicult to
clean out of the steel mill cleaning lines ;md it te~llds to blocl; rilters~
It ~vas also proposed in EE' 2~/ 37~ assigned to 3~1 a pol~olefin fibel-
roll co~ ising a cylindrical bod) formed Of a multiplicit~ Or segments ol ,
25 nonwoven web of randomly laid entangle-i pol)olefin fiber including ;m
adhesive binder ~vhich bonds adjacents fibers together vith a chemicall~
resistant bond at points of contact.
Because of the noted problems ~ith cleaning brushes, there is a
need for an improved cle~ning brush lor use in the caustic en~ ironments ol
30 steel strip mills and the lii;e. ~Ioreo~er, there is ;l need for a cleaning bru~
which has an improved resistance to caustic solutions to thereb) a~oid the
~forementioned
~D~,'o~
W095/05101 ~1 6 g 5 ~ 7 PCT~S94/09228
degradation of the phenolic resin material and the
resulting fluff caused by the destruction of the brush
fibers in the caustic environment.
5 Disclosure of Invention
The present invention overcomes the noted problems
in the art by providing a rotary brush suitable for use
in cleaning steel strip rolls and the like in caustic
10 environments, the brush comprising:
a cylindrical body rotatable about its
longit~l~;n~l axis, said body comprising a compressed
stack formed of a plurality of like-oriented annular
sections, each section assembled about a central
15 carrier, the sections each comprising a nonwoven web of
crimped bi-component fibers comprised of a first
polymer component and a second polymer component having
a melting temperature lower than the melting
temperature of said first polymer component, said first
20 polymer component and said second polymer component
attached to one another within each section by melt
bonding, said body having a density of between about 50
and about 250 kg/m3.
The fibers making up the compressed annular
25 sections are preferably a combination of polyolefins
(e.g. polypropylene and polyethylene) but may also
include polyesters and other materials. The annular
sections are preferably needle tacked prior to melt
bonding. Spacers may be interposed between the annular
30 sections so that the finishe~ brush will include a
plurality of annular sections and spacers in a
predetermined ratio.
A preferred method of manufacturing the rotary
brushes of the present invention comprises:
preparing an air laid web of crimped bicomponent
fibers comprising a first polymer component and a
WO95/05101 PCT~S94109228
2 1 68557
second polymer component having a melting temperature
lower than the melting temperature of said first
polymer component; bonding said first and second
polymer components to one another within said web by
5 heating said web to a temperature sufficient to soften
said second polymer component and cause melt bonding
between said polymer components within said web;
preparing a plurality of annular sections from said
nonwoven web; orienting said plurality of annular
10 sections for rotation about a common axis; compressing
said plurality of sections along said common axis with
a force sufficient to achieve a compacted configuration
of said sections having a density of between about 50
and about 250 kg/m3; and restraining said annular
15 sections in said compacted configuration.
Those skilled in the art will more fully
understand the details of the invention upon
consideration of the remainder of the disclosure
including the detailed description of the preferred
20 embodiments and the appended claims.
Brief Descri~tion of Drawings
In describing the preferred embodiments of the
25 invention, reference is made to the various figures
wherein:
Figure l(a) is a plan view of one surface of an
annular section of a nonwoven web suitable for
inclusion in a rotary brush body according to a first
30 emho~iment of the present invention;
Figure l(b) is a plan view of a surface of a
spacer suitable for inclusion in a rotary brush body
according to a first embodiment of the present
invention;
WO95/05101 2 1 68~57 PCT~S94/09228
Figure l(c) is an exploded view of the elements of
a rotary brush body according to a first embodiment of
the invention;
Figure l(d) is a perspective view of a completed
5 rotary brush body according to a first embodiment of
the invention;
Figure 2(a) is a plan view of an annular section
of a nonwoven web suitable for inclusion in a rotary
brush body construction according to a second
lO embodiment of the invention;
Figure 2(b) is a plan view of a surface of a
spacer suitable for use in a rotary brush body
according to a C~con~ embodiment of the invention;
Figure 2(c) is an exploded view of the elements of
15 a rotary brush according to a second embodiment of the
invention; and
Figure 2(d) is a perspective view of the completed
rotary brush according to the second embodiment of the
invention.
Det~iled Description
Details of the preferred embodiments of the
invention are now to be described in some detail. It
25 will be understood by those skilled in the art that the
structural details of these embodiments are not
limiting in any way but are merely illustrative of the
features of the invention. In describing the preferred
emho~iments, reference is made to the various figures
30 wherein the structural features of the invention are
identified by reference numerals and wherein identical
reference numerals indicate identical structures.
Referring to the various figures, figures l and 2
illustrate, respectively, first and second embodiments
35 of a compressed cleaning brush made of a nonwoven
thermally bonded fiber web. Figures l(a)-(d) show
Wo95tO5101 PCTtUS9~,0922~
21 68557
various features of a first embodiment of the
invention, showing the brush 30 and its components in a
tie-bolt construction. Figures 2(a)-(d) illustrate
another embodiment of the invention showing the same
5 brush material utilized in a bonded brush construction
40. In one aspect of the invention, the web includes no
phenolic resin binders. As those skilled in the art
will appreciate, it is also conceivable that the
brushes described herein could be made into a flap
lO brush type construction as well as the compressed
section type. It will also be appreciated that the
spacers described herein may not be essential in
certain type brushes such as smaller brushes, for
example.
In both of the embodiments described herein, a
nonwoven web is used to prepare the annular sections lO
and 20. In the web, it is preferred that bicomponent
fibers be used without additional resins (e.g. phenolic
resins) or the like to either protect or bind the
20 fibers of the web. Preferred web fibers include certain
polymer fibers such as polyolefin fibers, polyester
fibers and combinations thereof. More preferably,
polyolefin bicomponent fibers are used and most
preferably polyethylene and polypropylene crimped
25 staple fibers. In order to achieve a satisfactory brush
construction which is resistant to physical damage in
the caustic environments in which it will be used while
achieving a desired cleaning effect, the fiber diameter
can be important. Polyolefin fibers in deniers from
30 about 3 to about 40 denier are preferred. The fiber
length can range from being virtually continuous to
being of finite length. Crimped polyolefin staple
fibers having lengths from about 25 millimeters to
about 64 millimeters and more preferably from about 38
35 to about 50 millimeters have been useful in preparing
webs using conventional web forming equipment. The
--6--
WO9S/05101 2 1 6 8 5 5 7 PCT~Sg1l0522~
fibers may be only slightly crimped and the nature of
the fiber crimp includes conjugate or helical crimps.
Typically the fibers are thermoplastic bi-component,
i.e. sheath and core type or side-by-side type, one
5 component preferably being polypropylene and the other
preferably polyethylene. It is also contemplated that
polyester bicomponent fibers may be used.
The preferred construction of the web includes no
additional resinous materials to bond or protect the
l0 fibers of the web. An important aspect of the invention
is the manufacture of a bicomponent web wherein the
fibers are melt bonded to one another at the fiber
contact points within the web. In webs made from the
above mentioned preferred combination of polyolefins,
15 for example, the web is typically heated to the
temperature of the lower melting point polyethylene
component while the higher melting point polypropylene
component maintains its dimensions during the heating
step. During this heating step, the melted polyethylene
20 fibers bond with the polypropylene at the contact
points of the fibers within the web and the web
experiences only minimal shrinkage during bonding.
Preferred webs for the brush construction are those
made in web basis weights from about l00 grams per
25 square meter ("gsm") to about 500 gsm and those having
a web thickness of from about 5 millimeters to about 25
millimeters. The above described nonwoven webs may be
manufactured in a known manner by using a RANDO WEBBER
brand machine (Rando Machine Corporation, Macedon, NY)
30 or a FIBER LOCKER brand machine (James Hunter, North
Adams, Mass.).
For additional web strength (i.e. tensile and tear
strengths) a needle punching or needle tacking
operation performed on the web before melt bonding has
35 been found to be advantageous. Needle tacking is a
known t~chn;que which uses barbed or felting needles to
WO95/05101 PCT~S~ 9228
~t 68557
further entangle the fibers of a nonwoven web by
forcing the needles into the web in a predetermined
manner. Where needle tacking has been employed,
satisfactory webs have been achieved by using a needle
5 tacker machine fitted with a multiplicity of needles,
typically 15 x 18 x 30 x 3.5 CB Foster felting needles
fitted to the needle board. One preferred needle bar
layout includes five rows spaced apart at distances of
8.5 mm, 8.5 mm, 10 mm and 6.5 mm and with the needles
10 in each row evenly spaced at a distance of 12.5 mm.
After punching, the web is transported by
conveyors through a preheated oven. A 25 meter long,
center fed (e.g. counter current air flow towards the
web inlet end and concurrent towards the exit) oven
15 which is gas fired with an air flow at its inlet duct
of about 8000 cubic feet/minute (227 cubic
meters/minute) and about 4000 cfm at the exit ducts
(113 cubic meters/minute) has been used with
satisfactory results. Air flow is deflected through the
20 web with angled baffles above and below a carrier mesh
belt and the web is heated to the softening or melting
temperature of one of the component fibers. Where
polypropylene/polyethylene fibers are used, the web is
heated to a temperature from about 142C to about 148C
25 to induce heat fusion of the fibers. Those in the art
will appreciate that the temperature of the oven may be
varied over a range of temperatures depending upon the
weight of the web and the speed at which the web is fed
through the oven. It has been found that satisfactory
30 webs are produced by feeding the nonbonded web material
having a weight of about 200 gsm at a line speed of
four meters per minute through a 25 meter long oven
maintained at a temperature of about 142C. As the
weight of the web and/or the speed at which it is
35 carried though the oven increases, the temperature of
the oven must also be increased. A 250gsm web, for
WO95/05101 2 1 6 8 5 5 7 PCT~S91/0922~
example, has been adequately bonded at a temperature of
about 148C when conveyed through the oven at a
conveyor speed of five meters per minute.
The bonded web is cooled on exiting the oven with
5 an air knife and passed through a dancing nip roller
from which it enters a festoon accumulator prior to
being wound onto a master roll or "jumbo". Annular
sections lO, 20 are then punched from the manufactured
web. The sections lO, 20 are punched from the web in a
lO variety of diameters which will typically vary between
about 200 millimeters and about 600 millimeters,
depending on brush requirements as well as the
available physical space in the cleaning line(s) where
the finished brush is to be installed. It will be
15 appreciated that the invention does not require any
real limit to the web diameter or to the brush length
other than what might be imposed by engineering design
considerations.
The web sections lO, 20 are formed with center
20 apertures 70, 80 which may include opposing squared-off
keyway slots 90 (Figure la) to fit over a key element
on a support shaft. Additional slots 92 may be provided
to engage long tie-bolts (or axle bolts) lO0 which hold
the brush components together during the assembly
25 process. Where a glued brush construction is required,
tie bolts lO0 are not used and the sections 20 and
spacers 50 are adhered to a steel core llO as shown in
Figures 2(a)-(d), for example.
Spacers 50, 60 are provided for positioning
30 between web sections. The spacers 50, 60 are typically
made from a thermoplastic material such as
polypropylene, and are provided with a center hole
configuration similar (and usually identical) to the
apertures 70, 80 of the webs lO, 20. As shown, the
35 spacers are provided with a smaller outer diameter than
the annular sections lO and 20. The spacers are
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WO95/05101 2 1 6 8 5 5 7 PCT~S94109228
positioned between annular sections along an assembly
shaft such as the axle bolts lO0 in a predetermined
number of spacers per finished brush and at a
predetermined number of annular sections per spacer.
5 The section to spacer ratio in the brushes of Figures l
and 2, for example, is 3:l and the loading of annular
sections is typically 12.5 sections per 25 millimeters
of brush length. Those skilled in the art will
appreciate that this brush loading and the section to
lO spacer ratio is not limiting in any way. It is
contemplated that preferred brush loadings could range
between about 5 and about 20 sections per 25
millimeters and the preferred section to spacer ratios
could range from about l:0 to about 5:l. The use of
15 spacers 50, 60 within the construction of the brushes
disclosed herein is generally desired because the
spacers allow the annular web sections lO, 20 in the
finished brush some freedom to move laterally at their
peripheral portions for proper cleaning operations
20 while also firmly reinforcing the annular sections lO,
20 along their inner diameters. Spacers made of
polypropylene having an outer diameter of 200
millimeters, an inner diameter of lO9 mm and a
thickness of l.9 mm have been satisfactory.
In the embodiment of figure lc and ld, the annular
sections lO and the spacers 50 are assembled along the
axle bolts lO0 between end flanges 120. In the
embodiment of figure 2c and 2d, the sections 20 and the
spacers 150 are positioned along the core 60. After a
30 predetermined number of spacers and annular sections
have been assembled as described above, the spacers and
the annular sections are compressed under a sufficient
force at room temperature to make a dense nonwoven
brush structure of a predetermined length which can
35 then be loaded onto working shafts (not shown) for
cleaning operations in steel mills. The compacted
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WO95/05101 2 1 68557 PCT~S91~228
densities of the brushes of the present invention are
preferably at least about 5 kg/m3 and more preferably
between about 50 and about 250 kg/m3 and most preferably
about 125 kg/m3. The compaction force may be applied by
5 any suitable means available to those in the art. Once
the desired compacted density has been attained, the
annular sections and the spacers are then restrained in
their compacted configuration by any suitable means
such as the end flanges 120 or locking collars adapted
10 to be slidable on and mechanically engagable with the
axle bolts 100. Similarly, the sections 20 and the
spacers 150 of figure 2 may be held on the core 60 by
adhesive bonding. The preferred hardness of the
finished brushes as measured by the Shore A2 scale is
15 between about 5 and about 25.
In a preferred construction of the present
invention, the web is made from a side-by-side
bi-component polyethylene/polypropylene staple fiber
supplied by Chisso Corporation (Polypropylene Fiber
20 Division, 6-32 Naanoshima 3, Kita-Ku, Osaka 530, Japan)
and termed Chisso Type ES. The preferred staple fiber
is 18 denier and length 64 millimeters. The preferred
web weight is 250gsm. The web may be needle punched at
a punch density of about 8 punches/cm2by needletacking
25 at 760 cycles/min and with a penetration of 21
millimeters into the web at a line speed of four meters
per minute. Where lines speeds are increased to five
meters per minute, for example, the tacker rate should
be increased to about 950 cycles/min. Other line speeds
30 may require further adjustments which are within the
skill of those practicing in the field. A preferred
brush construction 30, 40 includes about 600 annular
sections and about 200 polypropylene spacers 50, 60,
each about 1.9 millimeters thick to form a 1.2 meter
35 long x 406 millimeters diameter compressed brush.
W095tO5101 PCT~S94/09228
2 1 68557
It has been found that when the brush of the
present invention is run in the same hot caustic
application as the conventional nylon/phenolic bonded
brush, the brush of the present invention exhibited an
5 extended life about 70% greater than the nylon/phenolic
brush. The brush of the invention has also been
observed to generate reduced "fluff" or waste during
normal use in caustic environments. These results
reflect a life extension of about 350~ along with a
10 significant reduction in mill maintenance when compared
with the tampico bristled brushes discussed above.
The following example is illustrative of the
manufacture, construction and the durability of a
preferred emhoA;ment of the nonwoven brushes of the
15 invention.
Example
A 250 g/m2, 50 mm thick nonwoven fabric is prepared
by processing ~CHISSO" polyethylene/polypropylene
sheath/core staple fiber (Chisso Corporation, Osaka,
20 Japan or Chisso America, Inc., New York, NY), 18 denier
x 38 _m length using an air lay machine available under
the trade designation ~RANDO WEBBER~ from Rando Machine
Corporation, Macedon, NY. The resulting fabric is
consolidated by needle tacking using a conventional
25 needletacker with a needle board loaded to 10 needles
per inch (3.9 per cm) with needles designated
15x18x30x3.5 CB, available from Foster Needle Company,
Manitowoc, WI. The needle tacker is adjusted to provide
85 mm needle penetration and 49 penetrations/in2 (7.6
30 penetrations/cm2). The thus consolidated fabric is
passed at 5 m/min. through a 25 meter long forced-draft
bonding oven heated to 148C. The resulting fabric is
about 10 mm thick, is well bonded and relatively stiff,
and has no fluffy appearance.
Annular sections of three different diameters are
then cut from the consolidated and bonded fabric. The
WO95/OSlol 2 16 ~ 5 5 7 rcT~ss4los228
majority of the sections are cut to provide an outer
diameter t"o.d.") of 406 mm and an inner diameter
("i.d.") of 109 mm, the i.d. further provided with 4
equiangularly spaced notches to accept an array of 4
5 axle bolts, and two symmetrical notches to provide a
keyway for mounting on an end use shaft. Lesser numbers
of sections are cut having outside diameters of 300 mm
and 255 mm, all with an inside diameter of 109 mm and
with the same array of notches an in the 406 mm
10 sections. The two smaller o.d. sections are used to
provide tapered or stepped ends for the final brush.
Polypropylene spacers of 200 mm o.d., 109 mm i.d., and
thickness of 1.9 mm are cut from polypropylene sheet,
also providing the notches to accommodate the axle
15 bolts and shaft keys. Having provided these various
sections and the spacers, the cleaning brush of the
present invention is now ready for assembly.
Four axle bolts are secured to an end flange in an
equiangular array identical to that of the axle bolt
20 notches provided in the sections and spacers. The end
flange is also provided with two opposing keyway
notches, likewise matching those provided in the
sections and spacers. Four 255 mm o.d. annular sections
are placed over the axle bolts so that the axle bolts
25 engage the axle bolt notches. A spacer is then placed
similarly over the axles bolts, followed by two 300 mm
o.d. sections, followed by a spacer, then followed by
two 406 mm o.d. sections and subsequently a spacer.
This assembly is continued by alternating three 406 mm
30 o.d. sections followed by a spacer until about 250
sections are loaded on the axle bolts. The assembly of
sections and spacers is then compressed under a force
of about 850 psi (5.9 MPa) and retained by a clamp
assembly. This entire loading procedure is then
35 repeated with three 406 mm o.d. sections followed by a
spacer until about 600 sections are loaded. The
-13-
WO95105101 2 1 6 8 5 5 7 PCT~S94/09228
assembly is completed by loading a spacer, two 300 mm
o.d. sections, a spacer, four 255 mm o.d. sections, and
finally, another end flange. The entire assembly is
then compressed under a force of about 850 psi (5.9
5 MPa) and the end flange is secured. The resulting
cleaning brush is 1.2 meters in length.
The cleaning brush is mounted on a keyed shaft and
can then be evaluated as a cleaning brush in a plating
operation where it is subjected to a heated (80C)
10 cleaning solution which is highly caustic, typically
having a pH of about 13. The brush will perform the
cleaning operation adequately, generating virtually no
fluff, and will have a useful life of nearly twice that
of a conventional nylon/resin brush.
Although preferred embodiments of the invention
have been discussed and described in some detail above,
those skilled in the art will appreciate that various
changes and modifications can be made to the described
embodiments without departing from the true spirit and
20 scope of the invention, as defined in the following
claims.
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