Note: Descriptions are shown in the official language in which they were submitted.
l 32 l173
ABRASIVE A~TICLE CONTAINING HELICALLY CRIMPED FIBERS
sAcK ROUND OF__HE INVENTION
This invention relates to articles for cleaning,
buffing, conditioning, or restoring surfaces.
For at least the last 25 years, abrasive articles
made from nonwoven fibers have been used for cleaning
floors and other surfaces.
Hoover, et al, U.S. Patent No. 2,958,593
discloses nonwoven fibrous abrasive articles of extremely
open structure having an extremely high void volume. This
article has been found to be useful in floor maintenance,
in hand scouring operations such as performed in domestic
kitchens, as well as in various industrial abrasive
operations.
McAvoy, U.S. Patent No. 3,537,121 discloses a
soft, resilient compressible polishing pad having a lofty
fibrous nonwoven structure bonded by a soft, tough resin
containing a finely divided soft mineral filler. This pad
is comparable to pads made of lamb's wool with respect to
ability to impart luster to buffable waxes. This pad can
be used to clean and restore the surface of hard polymer
coatings without powdering. This pad also does not scratch
or abrade the surface, nor does it impart swirl marks to
the finish of the surface.
Fitzer, U.S. Patent No. 4,227,350 discloses a low
density abrasive product comprising a uniform cross
section, porous, lofty web of autogeneously bonded
continuous, undulated, interengaged filaments. The web is
impregnated with a tough binder resin which adherently
bonds the filaments of the web together and also bonds a
multitude of abrasive granules, uniformly dispersed
throughout the web, to the surface of the filaments.
Although the articles disclosed in the
aforementioned patents are extremely useful for the
purposes for which they are intended, they rapidly lose
their efficiency as they become saturated with dirt. It is
1 32 1 073
known that as the void volume of a nonwoven pad i9 lncreased, lts
abllity to absorb more dlrt ls lncreased. However, A8 the vold
volume is lncreased the life of the pad 18 slmultaneously decreas-
ed. In vlew of thls problem, lt has long been deslred to provlde
a nonwoven flbrous pad havlng a hlgh vold volume and a hlgh level
of durablllty.
SUMMARY OF THE INVENTION
Thls lnvention provldes a low denslty, nonwoven abraslve
artlcle havlny a nonwoven flbrous web comprislng hellcally crlmped
flbers derived from synthetlc organlc materlal. At least about
30% by welght of the fibrous web of this product be made of hell-
cally crlmped flbers.
The hellcally crlmped flbers must have crlmp frequency
hlgh enough so that the web formed therefrom ls lofty and open,
but they must not have so hlgh a crlmp frequency that they cannot
be processed by conventlonal nonwoven web-maklng equlpment. It ls
preferred that the hellcally crlmped flbers be stablllzed or set,
preferably by heatlng the flbers, so that subse~uent heatlng
thereof wlll not adversely affect the character of the hellcally
crlmped flbers and nonwoven webs produced therefrom.
Optlonally, the nonwoven web used ln thls lnvent~on can
contaln stuffer box crlmped flbers and melt bondable flbers. When
actlvated by heat, the melt bondable flbers help to stablllze the
nonwoven webs of thls lnventlon.
Dependlng upon the lntended appllcatlon of the artlcles
of thls lnventlon, flllers, colorants, abraslve partlcles, or
addltlonal blnders can be lncorporated lnto the nonwoven web.
Because the nonwoven abraslve artlcles of thls lnventlon
are more open and lofty than those of the prlor art, they are
capable of belng fllled wlth more debrls durlng use. Although
they are more open and lofty, they
1 32 1 073
--3--
are more durable than nonwoven abrasive articles of the
prlor art.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view, greatly enlarged, of an
article of this invention.
FIG. 2 is a side view in elevation of an article
of this invention.
DETAILED DESCRIPTION
As used herein, the term "abrasive article" is
intended to include articles which can perform any one or
more of the following functions: rubbing, wearing away,
polishing, cleaning, buffing, or otherwise conditioning.
The abrasive articles of this invention comprise
nonwoven webs that are characterized by being comprised of
helically crimped fibers. Fibers are crimped into a
helical configuration by relief of bi-lateral differential
forces in a fiber or composite fiber. These bi-lateral
differential forces are produced by either coextrusion of
polymers having at least some stress/strain differential
properties, or induction of differential stress by passing
the fiber over an edge. Although helically crimped
synthetic fibers are well known, the use thereof in
nonwoven abrasive products has never been disclosed.
Helically crimped fibers useful in the practice
of this invention must have a sufficiently high degree of
crimp to form a lofty, open nonwoven web but not so high a
level of crimp that these fibers cannot be processed by
conventional nonwoven web-makin~ equipment.
Preferably the void volume is maintained within
the range of from about 85 percent to at least about 95
percent. Structures wherein the void volume is somewhat
less than 85 percent are useful for the purposes of this
invention though not ordinarily recommended. On the other
hand, where the void volume is decreased below about 75
percent, it has been found that the outstanding and
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advantageous propertles dlmlnlsh rapldly. For example, the ready
flu~hablllty or cleanablllty of the floor cleanlng structures, and
therewith the abrasive cutting rate, etc. drops off.
It ls preferred to form the web component of our combl-
nation structures from synthetlc flbers such as nylon and poly-
esters (e.g., "Dacron~' ). The unlformlty and quallty of such
types of flbers can be closely controlled. Also, these flbers
retaln substantl~l of thelr physical properties when wet with
water or olls. Because the artlcles hereof often are sub~ected to
water, olls, cleaners, chemlcals, and the like, flbers should be
selected whlch maintain substantlal of thelr essentlal character-
istlcs when sub~ected to medla to which they will be exposed ln
the deslred partlcular use. However, lt may be mentloned that
certain deficlencies, e.g., low wet strength, in some flbers may
be lmproved by appropriate treatment thereof.
Typlcally, helically crimped fibers have about 1 to 15
full cycle crimps per 25 mm flber length, whlle stuffer box crimp-
ed flbers have about 3 to 15 full cycle crimps per 25 mm flber
length. In the artlcles of the present lnventlon, when hellcally
crlmped fibers are used in con~unctlon wlth stu~fer box crlmped
flbers, lt ls preferred that the hellcally crlmped flbers have
fewer crlmps per speclfled length than the conventlonal stuffer
box crimped flbers. As a typlcal example, for an artlcle comprl-
sed solely of 50 denler flber, hellcally crlmped flbers having
about three full cycle crlmps per 25 mm can be advantageously used
ln con~unctlon wlth stuffer box crlmped flbers havlng about flve
full cycle crlmps per 25 mm. The crlmp frequency ls measured
whlle the flbers are placed under very mlld stress. The "Low
Load", as glven ln Table I below, ls applled to the lndlvldual
flber before countlng the number of full cycle crlmps per 25 mm
flber length.
*
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TABLE I
Denier range Low load (g) }~igh load ~g)
0 - 25 Denier x 2 x 10 Denier x 50 x 10
26 - 40 0.05 3
41 - 75 0.1 5
76 - 125 0.2 10
126 - 175 0.3 15
10176 - 225 ~.4 20
Crimp index, a measure of fiber crimp elasticity
is preferably about 35 to 70 percent for helically crimped
fibers, which is about the same as for stuffer box crimped
fibers. Crimp index can be determined by measuring fiber
length with appropriate "High Load" attached, then
subtracting fiber length with appropriate "Low I.oad"
attached, and then dividing the resulting value by fiber
length and multiplyinq that value by 100. The crimp index
can also be determined after exposing the test fibers to an
elevated temperature, e.g. 135C to 175C for 5 to 15
minutes, and this value compared with the index before heat
exposure. Crimp index measured after the fiber is exposed
for 5 to 15 minutes to an elevated temperature, e.g. 135C
to 175C, should not significantly change from that
measured before heat exposure. The load can be applied
either horizontally or vertically.
By and large, the length of the fibers which may
be employed is dependent upon the limitations of the
processing equipment upon which the nonwoven open web is
formed. However, depending on types of equipment, fibers
of different lengths, or combinations thereof, very likely
can be utilized in forming the lofty open webs of the
desired ultimate characteristics herein specified. Fiber
lengths suitable for helically crimped fibers preferably
range from about 60 to about 150 mm, whereas suitable fiber
lengths for stuffer box fibers tange from about 25 to about
-
1 32 1 073
70 mm. Llkewise, the thickness of the flbers usually ls not cru-
clal (apart from processlng), due regard belng had to the re~lll-
ence and toughness ultlmately deslred ln the resultlng web.
Generally, larger denler flbers are preferred for more abraslve
artlcles, and smaller denler flbers are preferred for less abra-
slve artlcles. Flber slze must be suitable for lofty, open, low
denslty abraslve products. Typlcally, flber slze ranges from
about 6 to about 400 denler per fllament.
The hellcally crlmped flbers are preferably stablllzed
or set, preferably by appllcatlon of heat, so that, lf they are
subsequently heated to cure a subse~uently applled adherent coat-
lng, the crlmp frequency wlll not be signlflcantly changed. To
lnsure that crlmp frequency wlll not be changed and that nonwoven
webs made from hellcally crlmped flbers wlll not change apprecl-
ably ln thlckness when sub~ected to temperatures ln ~he range of
150C to 175C, the temperature for curlng adherent coatlngs,
hellcally crlmped flbers are preferably heat set at temperatures
at least sllghtly hlgher than these curlng temperatures. Change
ln crlmp frequency prlor to or durlng lnltlal flber bondlng pro-
cess would cause the thlckness of the nonwoven webs formed ofthese flbers to change excesslvely or cause the webs to become
excesslvely weak, and consequently unsultable for use ln lofty,
open nonwoven abraslve products.
Mlxtures of hellcally crlmped and conventlonal stuffer
box crlmped synthetlc organlc flbers can be used ln the practlce
of thi~ lnventlon. Nonwoven webs sultable for preparlng low den~-
slty nonwoven abraslve products of thls lnventlon co~prlse at
least about 30% by welght of hellcally crlmped synthetlc organlc
flbers, more preferably at least about 50% by weight of hellcally
crlmped synthetlc organlc flbers, and ~ost preferably at least
about 70% by welght of hellcally crlmped synthetlc organlc flbers.
A~
1 32 1 073
As compared wlth nonwoven low denslty abraslve pads con-
talnlng less than about 30~ by welght hellcally crlmped flbers,
nonwoven low denslty abraslve pads of thls lnventlon have more
reslstance to wear and dlslntegratlon. Increaslng the hellcally
crlmped flber content of these nonwoven abraslve pads generally
lmproves performance. It should be noted that nonwoven webs and
abraslve products made from nonwoven web~ contalnlng at least
about 30% by welght hellcally crlmped flbers have greater thlck-
ness, glven e~ual flber slze and welght, when compared to webs and
abraslve products made from conventional stuffer box crlmped
flbers. Although nonwoven, lofty, open abraslve products whlch
have greater loft or thlckness for a glven flber welght, flber
slze, coatlng materlal, coatlng welght, and abraslve content would
be expected to be less reslstant to wear and dlslntegratlon under
severe use conditions, the abraslve pads of thls lnventlon, whlch
contaln at least 30% by welght hellcally crlmped flbers, exhlblt
both a hlgher level of openness and a hlgher level of durabllity
than do abraslve pads contalnlng less than 30% by welght hellcally
crlmped flbers.
U.S. Patent No. 3,595,738 dlscloses methods for the
manufacture of hellcally crimped blcomponent polyester flbers
sultable for use ln thls lnventlon. The flbers produced by the
method of that patent have a reverslng hellcal crlmp. Flbers
havlng a reverslng hellcal crlmp are preferred over flbers that
are hellcally crlmped ln a coiled configuratlon llke a colled
sprlng. However, both types of hellcally crlmped flbers are
sultable for thls lnventlon. U.S. Patent No. 3,868,749, U.S.
Patent No. 3,619,874 and U.S. Patent No. 2,931,089, dlsclose
varlous methods of edge crlmplng synthetlc organlc fibers to pro-
duce hellcally crlmped flbers. Edge crlmped fibers are usually
formed ln a unldlrectlonal colled conflguratlon but may be of the
reverslng hellcally crimped type or may be comblnatlons of
,,~ .
,f: . ' .
' ; ' ~ .
' - .
1 32 1 073
-a-
both types. Typically, reversing helically crimped fihers
have fewer ~rimps per ~lnit length than do unidlrectionally
colled hQlically crimped ~lbers.
Melt bondable fibers can optionally be used in
the practice of this invention to provide initial bonding
of the filaments of formed nonwoven web to increase web
integrity and to help stabilize the web in order to
facilitate application of subsequent coatings. Melt
bondable fibers suitable for this invention must be
activatable at elevated temperatures below temperatures
which would adversely affect the helically crimped fibers.
Additionally, these fihers are preferably coprocessable
with the helically crimped fibers to form a lofty, open
unbonded nonwoven web using conventional nonwoven web
forming equipment. Typically, melt bondable fibers have a
concenteic core and a sheath, have been stuffer box crimped
with about 6 to 12 crimps per 25 mm, and have a cut staple
length of about 25 to about 100 mm. Composite fibers have
a tenacity of about 2-3 g/denier. Alternatively, melt
bondable fibers may be of side-by-side construction or of
eccentric core and sheath construction. Preferred deniers
of melt bondable fibers are six and larger.
Many types and kinds of abrasive particles and
binders can be employed in the nonwoven webs of the
articles of this invention. In selecting these components,
their ability to adhere firmly to the fibers employed must
be considered, as well as their ability to retain such
adherent qualities under the conditions of use.
Generally, it is highly preferable that the
binder materials exhibit a rather low coefficient of
friction in use, e.g., they do not become pasty or sticky
in response to frictional heat. However, some materials
which of themselves tend to become pasty, e.g., rubbery
compositions, can be rendered useful by appropriately
filling them with particulate fillers. Binders which have
been found to be particularly suitable include
phenolaldehyde resins, butylat~d urea aldehyde resins,
.
1 32 1 073
epoxide resins, polyester resins such as the condensation
product of maleic and phthalic anhydrides and propylene
glycol, acrylic resins, styrene-butadiene resins, and
polyureth~nes.
Amounts of binder employed ordinarily are
adjusted toward the minimum consistent with bonding the
fibers together at their points of crossing contact, and,
in the instance wherein abrasive particles are also used,
with the firm bonding of these particles as well. Binders
and any solvent from which the binders are applied, also
should be selected with the particùlar fiber to be used in
mind so embrittling penetration of the fibers does not
occur.
Representative examples of abrasive materials
useful for the nonwoven webs of this invention include, for
example, silicon carbide, fused aluminum oxide, garnet,
flint, emery, silica, calcium carbonate, and talc. The
sizes or grades of the particles can vary, depending upon
the application of the article. Typical grades of abrasive
particles range from about 36 to about 1000.
Conventional nonwoven web making equipment can be
used to make webs of helically crimped fibers or blends of
helically crimped and stuffer box crimped fibers with or
without melt bondable fibers. Air laid nonwoven webs
comprising helically crimped fibers can be made using
equipment commercially available from Dr. O. Angleitner
(DOA), Proctor & Schwarz, or Rando Machine Corporation.
Mschanical laid webs can be made using equipment
commercially available from Hergeth KG, Hunter, or others.
During manufacture of crimped fibers, lubricants are
typically used to facility processing. However, excessive
lubricant coatings on the crimped fibers may impede
processing crimped fibers into nonwoven webs.
The following non-limiting examples will further
serve to illustrate this invention.
1 32 ~ 073
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Exampl e
A random air-laid nonwoven web having a weight of
about 460 y/m2 and a thickness of about S0 mm was formed by
means of a DOA machine, a commercially available web
forming device. The web was formed from a preblended
mixture o~ 70% by weight 60 denier helically crimped
polyethylene terephthalate polyester (PET~ staple fibers
and 30% by weight 15 denier stuffer box crimped bicomponent
polyester melt bondable fibers. The helically crimped
fibers were formed by edge crimping, were fully tensilized,
were cut to 75 to 100 mm staple lengths, had a tenacity of
3.2 g/denier, had 2.7 full cycle crimps per 25 mm, had a
crimp index of 42, and had crimp index after heat exposure
for 5 minutes at 175~C of 38. The melt bondable fiber was
a stuffer box crimped fiber having a bicomponent
sheath/core ~modified polyester/polyester) construction,
had a tenacity of 3 g/denier, had a staple length of 40 mm,
had 9 full cycle crimps per 25 mm, had a crimp index of 9,
and had a crimp index of 16 after exposure to heat for 5
minutes at 130C, and were activatable at 120 - 200C.
In an oven, low velocity air heated to
approximately 180C was forced through the web for three
minutes, causing the bicomponent melt bondable polyester
fiber to bond to and stabilize the nonwoven web. The
thickness of the nonwoven web was reduced slightly to about
45 mm.
A filled styrene-butadiene rubber latex saturant,
having about 70% by weight non-volatile materials was
prepared by combining the following ingredients in the
amounts indicated:
1 32 1 073
Amount
Inaredlent (part~ bY welaht)
Water 3.1
Carbox~lated styrene-butadlene rubber (SBR)
latex, contalnlng 65~ styrene (Amsco~es 5900,
commerclally avallable from Unlon 011
Chemlcals) 43.4
Hexamethylmethoxymelamlne (HMMM~ resln
(Cymel 303, commerclally avallable from
Amerlcan Cyanamld) 4.6
Calcium carbonate flller 41.5
Dlammonlum phosphate, 40% by welght ln
tap water 0.4
Hydroxypropyl methylcellulose, 3% *by welght
dlsperslon ln tap water ~Methocel F4M,
commerclally avallable from Dow Chemlcal Co.) 0.8
Slllcone emulslon surfactant (Q2-3168*,
commerclally avallable from Dow Cornlng) 0.1
Dloctyl sodlum sulfosucclnate surfactant
(Trlton GR5M, commercially avallable from
Rohm and Haas) 0.8
The saturant was applled by passlng the nonwoven web
between a palr of vertlcally opposed 250 mm dlameter rubber cover-
ed squeeze rolls. The rotatlng lower roll, whlch was lmmersed ln
the saturant, carrled saturant lnto the nonwoven web, so as to
evenly dlsperse lt therethrough. The wet nonwoven web was drled
and the saturant cured ln a hot alr oven at 175C for about flve
to seven mlnutes. The dry, coated nonwoven web had a thlckness of
about 38 mm and welghed about 1110 g/m2. The nonwoven web had
breaklng strengths ln the length and cross dlrectlons of 9.5 and
11.4 kg/25 mm sample wldth, respectlvely.
Abraslon resistance of the nonwoven web was determlned
by an accelerated wear llfe test on floor bufflng pad~ havlng a
dlameter of 430 mm and dle cut from the aforementloned web. A
rotatlng table, havlng a dlameter of 2.4 m and havlng a surface
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X\
. ' ', . .
1 32 1 ~73
made of fllled vlnyl floor tlle, was rotated at a rate of 10 revo-
lutlons per minute ~rpm). To cause accelerated wear, 4 strlps,
each of whlch was 100 mm wide and contained 50 grade coated abra-
slve, was adhered to the vlnyl floor tlle in a random radlal pat-
tern so that the nonwoven floor bufflng pad crossed over these
strlps as the table rotated. The floor bufflng pad was driven by
a commerclal floor bufflng machlne operating at 175 rpm. The
welght of the bufflng machlne forced the bufflng pad agalnst the
rotatlng table. The bufflng pad was held and drlven by a conven-
tlonal 430 mm dlameter holder/driver, the "Insta-Lok" Brand
Driving Assembly, commerclally avallable from Mlnnesota Mlnlng and
Manufacturlng Company. The buffing machlnP and holderJdriver had
a combined welght of about 59 kg. At the beglnnlng of the test,
the table and buffing machlne were caused to rotate and the buf-
flng machlne was lowered 50 as to brlng its full welght onto the
test pad. The test was contlnued untll the test pad was caused to
dlslntegrate by the action of the four abraslve strlps. The tlme
elapsed from the beginnlng of the test was recorded.
The average life of the buffing floor pads of thls exam-
ple was 6.8 mlnutes; the range was from 2.0 to 11.0 mlnutes.
ComParatlve ExamPle A
A nonwoven web was made from a blend of 30~ by weight 15
denier melt bondable fiber and 70% by welght 50 denler tenslllzed
polyester staple flber whlch had been stuffer box crimped, heat
set, and cut to a length of 37 mm. The web was made according to
the procedure descrlbed ln Example 1. The stuffer box crimped
fibers had a tenacity of 4 g/denler, had 5 full cycle crlmps per
25 mm, and had a crlmp lndex of 26 before and after 5 mlnute expo-
sure to a temperature of 125C. The nonwoven web welghed 465 g/m2
and was approxlmately 37 mm thlck. After saturatlon with the
coating composition and cured as described in Example 1, the drled
product welghed
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approximately 1170 g/mZ and was about 28 mm thick. When
tested by the accelerated wea~ test described in Example 1,
the average life of the control floor buffing pads was
determined to be 1.1 minutes, with a standard deviation of
0.2 mlnute.
Exam~s 2 - 6
Nonwoven webs were formed from 70% by weight 60
denier helically srimped polyethylene terephthalate
polyester fibers and 30% by weight melt bondable fibers as
described in Example 1. The webs were then coated with the
saturant described in Example 1. 1`able II sets forth the
composition of these samples as well as the strength
properties and the resistance to wear of the coated webs as
determined according to the procedure described in Example
1.
TABLE II
Final
Fiber Total thick- Ten2silel 2
20weig2ht weight ness ~10 N/m) Pad life
Example (g/m ) (g/m2) (mm) MD XD ~min) SD (min)
Control A 465 1170 28 S1 75 1.1 0.2
1 4551110 37 37 44 6.8 4.8
2 4051000 36 35 42 3.6 0.1
3 345 870 32 35 33 2.1 0.8
4 300 715 28 25 32 1.8 0.7
270 590 25 25 25 1.6 0.5
6 230 545 23 18 19 1.3 0.9
lMD means machine direction; XD means cross direction.
2 SD means standard deviation.
The data in Table I I show that buffing pads
containing helically crimped fibers have longer pad life
than do buffing pads containing only stuffer box crimped
1 32 1 073
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fibers, even when tl)e pads containing helically crimped
fibers had thicknesses and weights below that of the pads
containing only stuffer box cri~ped fibers.
Exa~le 7
A nonwoven web was prepared by blending of 30~ by
weight lS denier melt bondable fiber (as described in
Example l), 35% by weight 60 denier, helically crimped
polyester staple fibers (as described in ~xample 1), and
35% by weight 140 denier helically crimped tensilized
polyester staple fiber which had been cut to 75 to 100 mm
in length. The 140 denier fiber had 1.6 crimps per 25 mm,
had a tenacity of 3.4 g/denier, and had a crimp index of 52
before and after exposure to heat (5 minutes at 175C).
The nonwoven web was heated for three minutes to activate
the melt bondable fibers to produce a web havinq a weight
of 500 g/m2 and a thickness of 31 mm. After saturation
with the saturant described in Example 1 and heat treatment
to cure the binder, the total weight of the web was about
1180 g/m2. Thickness of the dry saturated product was 30
mm. Average accelerated wear life was 4.5 minutes, with a
standard deviation of l.1 minutes.
Comparative Exam~
A nonwoven web was made by blending 30% by weight
15 denier staple binder fiber (as described in Example 1),
35% by weight 50 denier stuffer box crimped polyester
staple fiber ~as described in Comparative Example A), and
35% by weight lO0 denier stuffer box crimped tensilized
polyester staple fiber, which had been cut in 75 to 100 mm
lengths. The nonwoven web was heated for 6 minutes at
125C to activate the melt bondable fibers. The nonwoven
web initially weighed 490 g/m2. After saturation with the
saturant described in Example 1 and curing to dry the
saturant, the dry product weighed about 12]0 g/m2 and was
about 25 mm thick. Average accelerated wear life was 2.7
minutes, with a standard deviation of 0.4 minute.
-15-
1 32 1 073
Example~ 8-11
Nonwoven abrasive products were made havlng
various combinations of staple fibers, including
conventional stuffer box crimped fibers, bicomponent melt
bondable fibers, and helically crimped (edge crimped)
fibers. Nonwoven webs were formed from the fibee
compositions set forth in Table III by means of a Hergeth
mechanical nonwoven forming machine.
T~sLE III
Weight of
nonwoven
Example Fiber description web (g/m2)
8 50~ 50 denier ~elt bondable
copolyester
50% 65 denier helically crimped
nylon 66 124
9 25% 50 denier melt bondable
copolyesterl
75~ 65 denier helicfllly crimped
nylon 66 131
50% 50 denier stuffer box crimped
nylon 66
50~ 65 denier helically crimped
nylon 66 135
11 100% 65 denier helically crimped
2S nylon 66 135
Comparative C lO0~ 75 denier stuffer box crimped
nylon 66 138
Comparative D 50% 75 denier stuffer box crimped
nylon 66
50% 50 denier melt bondable copolyester 130
The fiber was of the core and sheath type, the core
comprising polyethylene terephthalate, the sheath
comprising a copolyester of ethylene terephthalate and
isophthalate.
The following table sets forth the properties of
the 50 denier melt bondable fibers, 65 denier helically
crimped fibers, and 75 denier stuffer box crimped fibers.
1 32 1 073
16
TA~LE IV
Crlmps index Crlmps lndex
Tenaclty Crimps ~before heat (after heat Length
Fiber (~/denler) /25 mm exP_sureLexPosure)(mm)
50 denler melt
bondable 2.1 6.5 20.8 -- 70
65 denler
hellcally
crlmped 4.9 1.8 13.6 13.9 110
75 denler
stuffer box
crlmped 3.6 7.5 42.8 -- 50
The nonwoven webs of Examples 8, 9, and Comparative
Example D were passed at the rate of 6 meters per mlnute through a
4 meter long hot air o~en at 170C to actlvate the melt bondable
fibers. Bonded webs of Examples 8, 9, and Comparatlve Example D
and unbonded webs of Examples 10, 11, and Comparatlve Example C
were coated wlth the prebond reslnous blnder descrlbed in Table V
below.
TABLE V
Amount
(percent
Component by welaht)
Polymethylene polyphenyl polylsocyanate
(Mondur MRS, commerclally avallable
from Mobay Co.) 38.58
Polypropylene glycol, PPG 425 12.86
Xylol . 44.58
Potasslum lactate capsules
(75% actlve as descrlbed ln U.S.
Patent No. 3,860,565) 3.94
Slllcone Defoamer Y-30
commerclally avallable from Dow Cornlng Corp.)0.04
The coatlng was applled to the nonwoven web by means of
a two-roll coater and then cured by passing the coated web through
a hot alr oven 18 meters long at a temperature of 150C and at a
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speed of 6 meters per mlnute.
The slurry coatlng set forth ln Table VI below was then
applled by means of roll coatlng to each of the prebonded nonwoven
webs of Examples 8, 9, lO, and 11 and Comparative Examples C and
D.
TABLE VI
Amount
(percent
ComPonent bY welght)
Propylene glycol monomethyl ether 23.02
Llthlum stearate 1.86
Phenol formaldehyde thermosettlng resln, 70% 22.22
Alumlnum oxlde abraslve, grade 100-15051.90
Colloldal slllca (Cabosll M5) 1.00
After being coated, the nonwoven webs were passed
through a 4 meter long hot alr oven at 165C at 1.5 meter per
mlnute to cure the reslnous blnder. Web welghts, coatlng welght,
web thlcknesses, and tenslle are set forth ln Table VII.
TABLE VII
Flnlshed
Flber Prebond Total web Tensile
welght added dry welght thlcknessl ~N x 102 ~m~
Exam~le (a/m2) (a/m2) (a/m2) (mm) MD CD
8 124 105 1020 11 21 8
9 131 97 1045 12 24 9
135 67 1045 10 26 9
11 135 90 1065 14 3011
Compar-
ative C 138 85 1090 7 2410
30 Compar-
ative D 130 85 1030 4 15 6
average of nine web thlckness measured under
a pressure of 115 Pa
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Discs were cut Erom each of the wehs of Examples
8, 9, lO, and 11 and Comparative Examples C and D. These
discs were lS0 mm in diameter and had 32 mm center holes.
The six discs were mounted on an arbor and compressed to 25
mm thickness by flanges 125 mm in diameter having a 32 mm
center hole. The compressed and restrained discs were then
rotated at 2000 rpm. A workpiece of type 6061 perforated
aluminum sheet, S0 mm by 280 mm, was urged for three
minutes against the rotating abrasive disc with a 22 ~
force and moved back and forth 150 mm against the rotating
discs. The workpiece had 6.4 mm staggered pattern, had 6.4
mm diameter perforations, had holes spaced 8.7 mm on
center, was 48~ open, and was 1.63 mm thick. Weight loss
of the six discs and weight loss ~cut) of the perforated
aluminum sheet were recorded in Table VIII.
~ABLE VIII
Cut Wear Efficiency
20Example ~q)(percent) cut/% wear3
8 0.64 21.2 0.041
9 0.53 13.2 0.049
0.36 7.9 0.062
11 0.47 6.4 0.094
Comparative C 0.30 8.1 0.045
Comparative D 0.61 21.9 0.039
The pads of Examples 10 and 11, which contained
50% or more helically crimped fibers, showed equal or
better cut and much greater efEiciency than the pad of
Comparative Example C. The pads of Examples ~ and 9 showed
enhanced cut or efficiency when compared with the pad of
Comparative Example D.
Various modifications and alterations of this
invention will become apparent to those skilled in the art
without departing from the scope and spirit of this
` -19- 1 32 1 073
invention, and it should be understood that this invention
is not to be unduly limited to the illustrative embodiments
set forth herein.
