Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02290494 2004-03-04
Mar-04-Ob 04:~tpm From-SIkBAS LTD 416595 1306 T-1t8 P:006/02T F-1~4
I
CELLUL~SIC WEB, METHI:?I~ AND AFPAItATUS FOR MAK.IhTG THE SAIVIE
USING PAPERMAICIN .t"~r BEL.T HAV1NG ANGLED CROSS-SECTiCNAL
. STRUCTURE, ~,ND METHOD OF MAKING THE BELT ~ .
FIEI~D OP TIC INVENTION
The present invention is related to processes for malting stroxlg, soft,
absorbent cellulo5ie webs.. ' Ii~!'ore particatlarly, this inveritioa is
concerned v~rith
strttetured cellalosic webs having low density regions.aad high.deztsity
regions, and
with papermaking belts utilised for making such paper webs. - . . .
HACK!GItO~Ut3D DF TIC IN~VENITCrN
Paper prd~ucts are used for s variety of psupasss.. Paper towels, facial
tissues;
toilet tissues, and.the lika are iru const~uat use.'s~ modrran indu~ialized
societies. The
large demand for~~eh paper products has created a deznand.far improved
versions of
the preduci5. lfthe paper products such as paper towe3s, foetal tissues,
toilet tissues,
and the like arc t~ perforaz their i»tayded tasla and to iind wide
aceeptattce, they
_ - ~ ~ must possess cotts,in phy~cal oharacceristics. Among the..morc
important .of these
characteristics arc ~rtr.~~31, softne~ and absosbauy.
Stretsgth is the abt~ity of a paper wed to retain 'rts physical irwt~egrity
daring use.
Sofiitess is the pleasing tactile sensation consurna-s percdve when they use
the
paper for its intendetl-pctrpos~s. . . ~ . .
- Absorbency is the eharactuistia of the paper that allows the paper tc~ take
up'
- , . snd retain fluids, particularly water and aqueous solutiosts sttd
suspensions.
lmpot't$ut not co~llr is the absal~tc quantity .of #luid a givar $mount of
paper ~I hold,
but also the rate at which ttte pspcr will absorb the fltud_
Through-air dryuig papexmaldn$ belts comprising g reinforcing structure sad a -
resinous frame~~ ~ otlt are descra'bed in commonly assigned U.S. Patatt'
4,514,345 .
issued t4 Johnson d al. on A.pr_ 30, 1985; U.S. Paten't 4,528,239 issued to
Trokh~an
on July 9, t5~85; U.S. Patent 4,529,~8tJ issued to T~alcharx on July 16, 1985;
~U.S_
Palest 4.437,859 issncd to Troldtan on loll. 2Q, 1989; U.S. pster~t 5,334,2$9
issued
to 'frokhan et a1 on Aug. 2, 1994.
The paper produced on the belts disclosed in these patents is charaatezised by
having two physically distinct regions: a continuous netr~rark region having a
CA 02290494 2004-03-04
Mar-D4-04 04:2Bpm from-SIMBAS LTD 416595 7306 T-178 P.007/027 F-124
2
relatively high density and a re;~ion comprised of a plurality of domes
dispersed
throughout the whole of the network region. The domes are of relatively low
density xnd relatively iaw.intrinsic strength compared to the network regions.
Such
belts have been used to produce commercially successful products such as
Hounty
paper towels and Charmin Ultra toilet tissue, both produced and sold by the
instant
assignee.
U'.S. Patents 5,245,Q2S issued to Trokhan c;t al. on Sep. 14, 1993; and
5,527,4.28 issued to Trokhan et al. on June 18, 1996, disclose a cellulosic
fibrous
structure comprising a plurality of regions: an essentially continuous first
region of a
relatively high basis weight; a second region of a relatively low or zero
basis weight
and circumscribed by and adjacent the first region; and a third region of an
intermediate basis weight and juxtaposed with the second region. A forming
belt for
producing such a paper comprises a patterned array of discrete protuberances
joined
to a reinforcing scrueture. Annuluses between adjacent protuberances provide
space
into which papermaking fibers may he deflected to form the first region. >rn
addition,
each individual protuberance may have an aperture therein. The apertures in
the
individual protuberances also provide space into which the papermalfing fibers
may
deflect to form the third region.
Still. a search foe improved products has continue.
It may be dcsirai7le in some :astanc~s~ to produce >~ellulosic webs having
"angled" cross-sectional pancrns, i~.c., the webs which » where viewed in the
cross-
section ~ have the domes extending from an essentially continuous network
region
such that the domes ,are not generally perpendicular, but instead are xcu~tcly
angled,
rtlative to the plane of the netrwarl: region. Particularly, such "angled"
dames may
irnprovr the web's softness due to increased collapsibility of the angles
domes,
compared to the prrpendieularly upstanding domes. In addition, it is believed
that
such angled suucttu~s will. possess an ability tc~ direct absorbed fluids in a
desired
(and prcdcterminexl) direction, based on the specific (and a3so predetermined)
orientation of the domes in the web. Such propcrtie~ may be very bariefeial in
a
variety of disposable products.
Therefore, it is an object of an aspect of the present iztventiozt to provide
a
ceilulosic web having at least two regions: an essentially continuous regiozt
and a
region comprising a patterned array of discrete domes or knucldes extending
from
the essentially continuous region such that the axes of the domes or knuckles
and the
general plane of the essentially continuous region form acute angles
therebetween.
Zt is another object of an aspect of the present inventiozt to provide a
process.of
making such cellulosic webs.
CA 02290494 2004-03-04
ldar-04-04 04:26pm From-SII~BAS LTD 416595 T306 T-1T8 P.006/D2T F-124
a
It is still another object of an aspect of the present invention to provide a
paperrnalting belt for producing such cellulosic webs.
Zt is a further object of an aspect of the present invention to provide a
process
ofmaking suchpapermaking belt.
SUMMARY CIF THE IN~I~NTIaN
A macroscopically rnonoplanar papermaking belt of the present invention
may be used in a papermalcir3g machine as a forming belt andlor as a through-
air
drying belt.
The through-air drying belt comprises a resinous framework having a we'b-
side surface which defines an 3~-Y plane, a backside surface opposite the web-
side
surface, a Z-direction perpendicular to the 3~-Y plane, and a plurality of
discrete
deflection conduits extending between the web-side surface and the 'backside
surface. Preferably, the plurality of conduits comprises a non-random
repeating
patterned array. &ieh of the discrete conduits has art axis and walls. The
axes of at
least same of the discrete conduits and the Z-direction farnra, acute angles
therebetween. Preferably, the throu,gla-air drying belt farther comprises an
air-
permeable reinforcing structure positioned between the web-side surface and
the
backside surface of the resinous framework. The reinforcing structure has a
web-
facing side and a machine-facing side apposite the web-facing side.
In the through-air drying belt, the web=side surface of the framework has an
essentially continuovss web-side network formed thereia. and the backside
surface of
the framework has a backside network formed therein. The web-side network
defines web-side openings, and the backside network defines backside openings
of
the discrtta .conduits. The web-side openings are off set relative . to the
corrcsporrding bacirsid~e operrixtgs within the X-Y plane in at least one
direction
perpendicular to the Z-direction. The tliscrefe conduits may be tapered,
preferably
negatively tapered, relative to their, respective axes in at least one
direction
perF.:.oiicular to the Z-direction,
The forming i5elt of the present invention comprises an air-permeable
reinforcing structure and a resinous framework joined to the reinforcing
s:~.~cture.
The reinforcing structure has a web~facing side def n'sng an X-Y plane, a
machine-
facing side apposite the web-facing side, and a Z-direcuort perpendicular to
the 7C-Y
plane. The resinous framework is comptis~ed of a plurality of discrete
protuberances
joined to arid extcziding from the reinforcing structure. Each of the
protuberances
has an axis, a top surface, a t~ase~surf"ace opposite the top surface, and
wails spacing
apart and intcrconneeting'the tap surface and the base surface. Preferably,
the
CA 02290494 2004-03-04
i~ar-04-04 04:29pm From-SIaBAS LTD 416595 T306 T-1t6 P.009/02T F-124
4
discrete protuberances are circumscribed by and adjacent to an area of
essentially
continuous deflection conduits. A plurality of the tap surfaces defines a web-
side
surface, and a pluzality of the base surfaces defines a backside surface of
the resinous
frarz~ework.
In the forming belt of the present invention, the axes of at least some of the
protuberances and the Z-direction form an acute angles therebetween. The top
surfaces
of at least some of the protuberances are off-set relative to the
corresponding base
surfaces of the same protuberances within the ?~-'Y plane in at least one
direction
perpendicular to the Z-direction. The web-facing side of the reinforcing
structure has
preferably an essentially continuous web-facing network ~ormod therein" which
web-
facing network is defined by the area of essentially continuous de#lectian
conduits- The
walls of at least some of the protuberances may be tapered relative the axes
of these
protuberances- Frefernbly, the plurality of protuberances comprises a non-
random
repeatitxg patterned array in the X-Y plane. Xn one embodiment, the plurality
of discrete
protuberances has a plurality of discrete deflection conduits extending from
the web-
side surface to the back surface of the resinous fi~xowork. Preferably, each
of the
plurality of discrete pzbtuberamees has at least one discrete deflection
conduit therein.
In both the through-air drying bolt and the forming belt, the backside surface
Fnay
optionally be textured.
According to an aspect ofthe presexlt invention, there is provided a
macroscopically monoplanar papermaking belt far use in a papermaking machine,
the
papennaking belt comprising a resinous framework homing a web-side surface
defining
an ~~-'f' plane, a backside surface opposite the web-side surface, a Z-
direction
perpendicular to the X-Y plane, and a plurality of discrete deflection
conduits
extending between the web-side surface and the backside surface, each of the
discrete
conduits having an axis and walls, the axes of at least same ofthe discrete
conduits and
the Z-direction forming acute angles therebetween.
A method of making the belt of the present invention comprises the steps of
{a) providing an apparatus for generatixrg curing radiation in a first
direction;
{b) proVidin~; a liquid photosensitive resin;
(c) providing a forming unit having a working surface and capable of receiving
the liquid photosensitive resin;
CA 02290494 2004-03-04
Mar-04-04 04:29pm From-SIMBAS LTD 416695 T306 T-1T6 P.O10/02T F-124
(d) providing an air-permeable reinforcing structure to be joined to the cured
phatnsensitive resin, the reinforcing structure having a web-facing side and a
machine-
faein,g side opposite said web-facing side;
(e) disposing said reinforcing structure in said forming unit;
(f) disposing flue liquid photosensitive resin in said forming unit thereby
Forming a coating of the liquid photosensitive resin, the coating having a
first surface
and a second surface opposite the first surface, and a prc-selected
t>faiclaoess defined by
these first and second surfaces;
(g) disposing the forming unit containing the coating of liquid photosensitive
resin in the ~at~di~etic::-.>-uay~: ~l~sat-+~e-fr ~t-s~.Ge~f tlte~,caa~g-and-
that direct:r::
Form an acute angie therebetween;
(h) providing a mask having opaque regions and transparent regions defining a
pre-selected pattern;
(i) positioning the mask between the first surface of tire ce~ating and the
apparatus for generating curing radiation such that the mask is in adjacent
relation with
the first strtface, the opaque regions of the mask shielding a portion of the
coating from
the curing radiation of the apparatus, and the transparent regions leaving
other portions
of the coating unshielded for the curing radiation of the apparatus;
(j) curing said unshielded portions of the coating, and leaving the shielded
portions of the coating uncured by exposing the coating to radiation having an
activating wavelength from t'he apparatus for generating curing radiation
through the
mask to form a partially formed belt;
(k) removing substantially all uncured liquid photosensitive resin from the
partially-formed belt to leave a hardened resixious structure which forms a
framework
having 3 Wpb-5lde 511T1~1Ce formed by the first surface being cured and a
backside
surface formed by the second surface being cured, Depending an a particular
predetersnined design of the desired framework (continuous framework for the
through-
ai~r drying belt, or the iiamework comprising the plurality of protuberances
for the
forming belt), the belt will have either a plurality of discrete conduits in
the re;ions
which were shieided from tire curing radiation by the opaque regions of the
mask, or a
plurality of discrete protuberances extending from the reinforcing struct~e in
the
regions which were not shielded and therefore became cured.
CA 02290494 2004-03-04
Mar-D4-04 04:29pm From-SIMBAS LTD 416595 t3D6 T-1t8 P.011/02t F-124
Sa
The steps (d) and (e) are the necessary sups for mixing the farmitag belt, and
the highly preferred steps for making the through-air drying belt.
According to another aspect of the present invenrion, there is provided a
method of making a macroscopically monoplartar papermaking belt, the method
comprising the steps of:
providing an apparatus for generating curing radiation in a first direction;
providing a liquid photosensitive resin;
providing a forming unit having a vrorking surface and capable of receiving
the
liquid photosensitive resin;
disposing the liquid photosensitive resin in the forming unit thereby forming
a coating of the liquid photosensitive resin, the coating having a first
surface and
a second surface opposite the first surface, the coating having a pre-selected
thickaness;
disposing the forming unit containing the coating of liquid photosensitive
resin therein in the frst direction, such that the first surface of the
caatin,g and
the first direction form an acute angle therebetween;
providing a mask having opaque regions and transparent regioxis, the regions
defining a pre-selected pattern;
positioning the mask between the first surface of the coating and the
apparatus far generating curutg radiation such that the mask is in adjacent
relation with the first Surface, the opaque regions of the mask shielding a
portion of the coating from the curing radiation of the apparatus, and the
transparent regions leaving other portions of the coating unshielded for the
curing
radiation of the apparzttus;
curing the unshielded portions of the coating, and leaving the shielded
portions of the coating uncuredby exposing the coating radiation having an
activating wavelength from the apparatus for generating curing radi atian
through
the mask to form a partially-formed belt; and .
removing substantially all uncured liquid photosensitive resin from the
partially-formed belt to leave a hardened resinous structure which forms a
framework having a v~.eb-side surface formed by the first surface being cured,
a
backside surface formed by the second surface being cured, a Z-direction
CA 02290494 2004-03-04
~dar-04-04 04:30pm From-SII~AS LTD 416595 T306 T-lT8 P.012/02T F-124
5b
perpendicular to the web-side surface, and a plurality of discrete conduits in
the
regions which were shielded from the curing radiation by the opaque regions of
the
mask, the conduits extending lxtween the web-side surface and the
backside surface, each ofthe conduits having an axis and walls, the axes of at
least same of the conduits and the Z-direction forming acute angles
therebetween.
A cellulosie web made by using the through-air drying belt having an
essentially continuous framework will have at least two regions disposed in a
non-
random and repeating pattern: a macroscopically manoplanar, patterned, and
essentially
continuous network r.;gion forming a network plane and preferably having
relatively
high density, and a domes region preferably having relatively law density. The
domes
region connprises discrete dames extending from the network plane in at least
one
direction Such that this at least one direction and the network plane form an
acute angle
therebetween.
According to another aspect of the present invention, there is provided a
macroscopically moncrplanar papezm,aking belt for use in a papermaking
machine, flee
papermaking belt comprising:
an air-p~nn~able reinforcing structure having a web-facing side defining an
X-Y plane, a maehW e-facing side opposite the web-Facing side, and a Z-
direction
perpendicular to the h-Y plane; and
a resinous frarnework comprised of a plurality of discrete protuberances
joined
to and extending from the reinforcing structure, eacb of the protuberances
having an
axis, a top stwface, a base surface opposite the tap surface, and walls
spacing apart and
irxtercannecting the top surface and the base surface, the axes of at least
some of the
protuberances and the 2-direction forming acute angles therebetween, a
plurality of the
top surfaces defining a web-side surface of the resinous framework, and a
plurality of
the base surfaces defining a backsi de surface of the resinous framework.
According to a further aspect of the present invention, there is provided a
method of making a macroscopically monoplanar papermaking belt, the znetbod
comprising the steps of;
providing an apparatus for generating curing radiation in a first direction;
providing a liquid photosensitive resin;
CA 02290494 2004-03-04
Mar-04-04 04:30pm From-SIMBAS LTD 416696 T306 T-118 P.013/02T F-124
Sc
providing a forming unit having a warkiug surface and capable of receiving the
liquid photosensitive resin;
providing an air..permeable reinforcing structure having a web-facing side
defining an ~-~,'' plane, a machine-faciztg side opposite the web-facing side,
and a Z-
direction perpendicular to the X-Y plane;
bringing at least a portion of the machine-facing side of the reinforcing
structure
into contact with the working surface of the Forming unit;
applying a coating of the liquid photosensitive resin to at least one side of
the
reinforcing structure so that the coating farms a first surface and a second
surface
opposite the first surface, the coating haviztg a pre-selected thiclmess;
disposing tl7e forming unit containing the coating of liquid photosensitive
resin
therein in the first direction such that the first surface of the coating and
the first
direction forax an acute angle therebetween;
providing a mask having opaque regions and transparent regions, the regions
defining a pre-selected pattern;
positioning the mask between the first surface of the coating and the
apparatus for generating curing radiation such that the mask is in adjacent
relation
with the first surface, the opaque regions of the rnaslc shielding a portion
of the
coating from the curing radiation of the apparatus, and the transparent
regions
leaving other portions of the coating unshielded far the curing radiation of
the
apparatus;
curing the unshielded portions of the coating, and leaving the shielded
portions
of the coating uncured by exposing the coating to radiation having an
activating
wavelength froxrt the apparatus for generating curing radiation through the
mask to
Corm a partially-fonnc;d belt; and
removing substantially all uncured liquid photosensitive resin from the
partially-formed belt to leave a hardened resinous structure which forms a
framework
having a web-side surface formed by the first surface being cured, a backside
surface
formed by the second surface being cured, a 2-direction perpendicular to the
web-side
surface, the framework being comprised of a plurality of discrete
protuberances joined
to and extending from the reinforcing structure, each of the protuberances
having an
axis, a base surface, a top surface, and walls spacin,~ apart and
interconnecting the base
CA 02290494 2004-03-04
Mar-04-04 04:30pm From-SIMBAS LTD 416595 2306 T-1TB P.014/027 F-124
5d
surface and the tap surface, the axes of at least same of the protuberances
and the Z-
direction forming acute angles therebetween, a plurality of the top surfaces
defining the
web-side surface of ik~e resinous framework, and a plurality of the base
surfaces
defining the backside surface of the resinous framework.
The cellulosic web farmed on the forming belt having the framework comprised
of the plurality of discrete protuberances will have at Least two regions
disposed in a
non-random and repeating gatxe~: a macroscopically planar and patterned first
region
defining an X-Y plane and preferably having a relatively high basis weight,
and a
second region preferably having a relatively Low basis weight and
circumscribed by and
adjacent to the first region. The first region comprises an essentially
continuous
network farmed over the area of essentially continuous conduits of the forming
belt's
framework. ',fhe second region is comprised of a
CA 02290494 1999-11-16
WO 98/53138 PCT/US98110166
6
plurality of discrete knuckles formed over the discrete protuberances of the
forming
belt's framework. The protuberances extend fram the first region in at least
one
"angled" direction such that this at least one direction and the X-Y plane
form an
acute angle therebetween. The web formed on the forming belt having the
discrete
deflection conduits through the protuberances may also have a third region
having
an intermediate basis weight relative to the basis weight of the first region
and the
basis weight of the second region, the third region being juxtaposed with the
second
region.
In its through-air drying aspect, a process for producing a cellulosic fibrous
web comprises the steps of:
(a) providing a plurality of cellulosic papermaking fibers suspended in a
liquid
carrier;
(b) providing a forming belt;
(c) depositing the plurality of cellulosic papermaking fibers suspended in a
liquid
carrier on the forming belt;
(d) draining the liquid carrier through the forming belt thereby forming an
embryonic web of the papermaking fibers on the forming belt;
(e) providing a macroscopically monoplanar through-air drying belt comprising
a
resinous framework having a web-side surface defining an X-Y plane, a backside
surface opposite the web-side surface, a Z-direction perpendicular to the X-Y
plane,
and a plurality of discrete deflection conduits extending between the web-side
surface and the backside surface, each of the conduits having an axis and
walls, the
axes of at least some of the conduits and the Z-direction forming an acute
angles
therebetween;
(~ depositing the embryonic web to the web-side surface of the resinous
framework
of the through-air drying belt;
(g) applying a fluid pressure differential to the embryonic web to deflect at
least a
portion of the papermaking fibers into the discrete deflection conduits and to
remove
water from the embryonic web into the discrete deflection conduits thereby
forming
an intermediate web which comprises a macroscopically monoplanar, patterned,
and
essentially continuous network region, and a domes region comprising a
plurality of
discrete domes protruding from, circumscribed by, and adjacent to the network
region, each of the domes having an axis, the axes of at least some of the
domes and
the Z-direction forming acute angles therebetween.
A process for producing the embryonic cellulosic fibrous web on the forming
belt of the present invention comprises the steps of:
(a) providing a plurality of cellulosic fibers suspended in a liquid earner;
CA 02290494 1999-11-16
WO 98153138 PCT/US98I10166
7
(b) providing a macroscopically monoplanar forming belt comprising an air-
permeable reinforcing structure having a web-facing side defining an X-Y
plane, a
machine-facing side opposite said web-facing side, and a Z-direction
perpendicular
to said X-Y plane, the forming belt further comprising a resinous framework
comprised of a plurality of discrete protuberances joined to and extending
from the
reinforcing structure, each of the protuberances having a base surface, a top
surface,
walls spacing apart and interconnecting the base surface and the top surface,
and an
axis, the axes of at least some of the protuberances and the Z-direction
forming acute
angles therebetween, a plurality of the top surfaces defining a web-side
surface of
the resinous framework, and a plurality of the base surfaces defining a
backside
surface of the resinous framework;
(c) depositing the cellulosic fibers and the carrier onto the forming belt;
(d} draining the liquid carrier through the forming belt, thereby forming a
macroscopically planar and patterned first region disposed in the X-Y plane,
the first
region comprising an essentially continuous network and preferably having a
relatively high basis weight; and a second region comprised of a plurality of
discrete
knuckles circumscribed by and adjacent to the first region and preferably
having a
relatively low basis weight, the knuckles extending from the first region in
at least
one direction, this at least one direction and the Z-direction forming an
acute angle
therebetween.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic top plan view of a papermaking belt of the present
invention having an essentially continuous web-side network and discrete
deflection
conduits.
FIG. lA is a schematic fragmentary cross-sectional view of the papermaking
belt taken along lines IA-lA of FIG. 1, and showing the discrete deflection
conduits
which are angled relative to the Z-direction.
FIG. 1 B is a schematic fragmentary cross-sectional view of the papermaking
belt taken along lines 1B-1B of FIG. 1.
FIG. 1 C is a schematic fragmentary cross-sectional view of the papermaking
belt of the present invention having angled and negatively tapered conduits.
FIG. 2 is a schematic top plan view of the papermaking belt of the present
invention comprising a resinous framework formed by discrete protuberances
encompassed by an essentially continuous area of deflection conduits.
CA 02290494 1999-11-16
WO 98/53138 PCT/US98I10166
8
FIG. 2A is a schematic fragmentary cross-sectional view of the papermaking
belt taken along lines 2A-2A of FIG. 2, and showing the discrete protuberances
which are angled relative to the Z-direction and positively tapered.
FIG. 3 is a schematic top plan view of a papermaking belt similar to that
shown in FIG. 2, and comprising a resinous framework formed by a plurality of
discrete protuberances having a plurality of discrete deflection conduits
therein.
FIG. 3A is a schematic fragmentary cross-sectional view of the papermaking
belt taken along lines 3A-3A of FIG. 3, and showing positively tapered
protuberances having negatively tapered discrete conduits therein.
FIG. 4 is a schematic top plan view of a paper web produced on the
papermaking belt of the present invention shown in FIGS. 1-1C, the paper web
having three zones of knuckles, the knuckles of each zone having a specific
orientation different from the orientations of the knuckles of the other two
zones.
FIG. 4A is a schematic fragmentary cross-sectional view of the paper web
taken along lines 4A-4A of FIG. 4.
FIG. 4B is a schematic fragmentary cross-sectional view of the paper web
taken along lines 4B-4B of FIG. 4.
FIG. 4C is a schematic fragmentary cross-sectional view of the paper web
taken along lines 4C-4C of FIG. 4.
FIG. 4D is a schematic fragmentary cross-sectional view of a prophetic web
produced on the papermaking belt of the present invention shown in FIGS. 3 and
3A.
FIG. 5 is a schematic perspective view of an apparatus for generating curing
radiation which can be utilized for curing a photosensitive resin to form a
resinous
framework comprising the papermaking belt of the present invention.
FIG. SA is a schematic cross-sectional view of the apparatus shown in FIG.
5.
FIG. 5B is a schematic cross-sectional view of the apparatus of controlled
radiation directing curing radiation in more than one pre-determined radiating
direction.
FIG. SC is a schematic cross-sectional view of another embodiment of the
apparatus of controlled radiation.
FIG. 6 is a schematic side elevational view of one embodiment of a
continuous papermaking process utilized in the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 6, the preferred embodiment of the papermaking belt I O of
the present invention is an endless belt. However, the papermaking belt 10 of
the
CA 02290494 1999-11-16
WO 98/53138 PCTIUS98/10166
9
present invention may be incorporated into numerous other forms that include,
for
example, stationary plates for use in making handsheets or other batch
processes, or
rotating drums for use with other continuous processes. As used herein, the
term
"papermaking belt 10," or simply "belt 10" is a generic term which includes
both a
forming belt l0a and a through-air drying belt lOb, both shown in FIG. 6. The
forming belt l0a travels in the direction indicated by a directional arrow
"A," and the
through-air drying belt i0b travels in the direction indicated by a
directional arrow
"B." Because both the forming belt I Oa and the through-air drying belt l Ob
possess
certain common characteristics, it is convenient in relevant parts of the
Specification
to refer to both the forming belt l0a and the through-air drying belt IOb as
simply
"the belt 10." However, when distinguishing between the forming belt l0a and
the
through-air drying belt 10b is necessary or helpful for understanding the
present
invention, the reference will be made to "the forming belt 10a," or to "the
through-
air drying belt lOb." Regardless of the physical form of the papermaking belt
10 and
its function in the papermaking process, the belt 10 of the present invention
has the
characteristics described below.
As shown in FIGS. 1-4C and 6, the belt 10 of the present invention has a web-
contacting side 11 and a backside 12 opposite the web-contacting side 11. As
should be clear from the definition, the web-contacting side 11 contacts and
thereby
supports a web 60 on the belt 10. The backside 12 contacts the machinery
employed
in the papermaking process, such as a vacuum pick-up shoe 17a and a multislot
vacuum box 17b and various rolls, etc. For clarity, as used herein, the web 60
is
referenced by the same reference numeral 60, regardless of a particular stage
of its
processing. The distinction between the various stages of the web's
processing,
although significant, does not require the use of different reference numerals
for the
purposes of describing the present invention. An adjective immediately
preceding
the term "web" will clearly and definitely indicate a particular stage of the
web's
processing, for example: "embryonic web 60," "intermediate web 60," "imprinted
web 60," "predried web 60," "dried web 60," and a final product -- "paper web
60."
FIGs. 1-3C show various embodiments of the belt 10 of the present invention.
FIGs. 1-1C illustrate the papermaking belt 10 which may preferably be utilized
as
the through-air drying belt lOb; and FIGs. 2-3A show embodiments of the belt
10
which can preferably be utilized as the forming belt 10a. The belt 10
comprises a
resinous framework 20 and a reinforcing structure 50 joined to the resinous
framework 20. It should be pointed out that the reinforcing structure 50 is
necessary
for the forming belt l0a and highly preferred for the through-air drying belt
l Ob.
CA 02290494 2004-05-31
The resinous framework, or simply framework, 20 has a web-side surface 21, a
backside surface 2? opposite the web-side surface 21, and a plurality of
deflection
conduits 30 extending between the web-side surface 21 and the backside surface
22
If desired, the backside surface 22 may be textured according to the commonly
assigned U.S. Patents: 5,275,700 issued Jan.4, 1994 to Trokhan; 5,334,289
issued Aug. 2, 1994 to Trokahan et al.; 5,364,504 issued Nov. 15, 994 to
Smurkoski , et al. The reinforcing structure 50 is preferably
positioned, between the web-side surface 21 and the backside surface 22 of the
framework 20. The reinforcing structure 50 is substantially liquid-pervious,
and
may comprise a foraminous element, such as a woven screen or other apertured
structures. The reinforcing. structure 50 has a web-facing side 51 and a
.machine-
facing side 52 opposite to the web-facing side 51. The web-facing side ~ 1 of
the
reinforcing structure 50 corresponds to the web-side surface 21 of the
framework 20,
and the rna~:hine-facing side 52 of the reinforcing structure 50 corresponds
to the ~'
backside surface 22 of the framework 20.
Ln the .embodiment shown in FIGS. 1-1C, the framework 24 comprises an_
cssenti.ally cot-;tinuous pattern, and the plurality ~of deflection conduits
30 comprises
a plurality of discrete orifices, or holes, extending from the web-side
surface 21 to
the backside surface 22 -of the frarr~ework 2U. .Prefezably, the discrete
conduits 30
are afir'anged in' a pre-selected patteriin the'frarnework 20. More
preferably, the
pattern of the arrangement of the conduits 30 is non-random and repeating. The
papenmaking belt 10 having a continuous framework 2Q and discrete deflection
conduits 30 may preferably be utilized as the through-air drying belt lOb. The
par~ermaking belt 10 having a continuous framewoFk 20 and discrete deflection
conduits 30 is primarily disclosed in the commonly assigned U.S: Patents
4,528,239
issued Jul. 9, 1985 to Trokhan; 4,529,480 issued Jul. 16, 1985 to Trokhan;
4,637,859
issued Jan. 20, 1987 to Trokhan; 5,098,522 issued Mar. 24,-1992 to Trokhan et
al.;
5,275,700 issued Jan. 4, 1994 to Trokhan; 5,334,289 issued Aug. 2, 1994 to
Trokhan;
and 5,364,504 issued Nov. 15, 1985 to Smurkoski et al.
In another embodiment of the belt 10 shown in FIGs. 2-3C, the framework 20
comprises a plurality of discrete protuberances 40 extending from the
reinforcing
structure 50 and adjacent to an area of essentially continuous deflection
conduits 70.
The discrete protuberances 40 are preferably circumscribed by the area of
essentially
continuous deflection conduits 70. In the embodiments shown in FIGS. 2-3C, the
region of essentially continuous deflection conduits 70 preferably defines an
CA 02290494 2004-03-04
Ilar-04-04 04:31pm From-SiwBAS LTD 416595 T306 T-1Z8 P.016/02T F-124
II
essentially continuous web-facing network 51 * formed in the web-facing side
51 of
the reinforcing structure SQ_
The term "essentially continuous" indicates that interruptions in absolute
gean~etrical continuity may be tolerable, while ,are not preferred, as long as
these
intetTUptions do not adversely affect the performance of the belt i0 of the
present
invention. It should also be carefully noted that embodiments (not shown) are
possible in which interruptions in the absolute continuity of t~lte framework
20 (in the
through-air drying belt 1 Ob) ~ ar interruptions irt the absolute continuity
of the
conduits 70 (in the forming belt IOa) are intended as a part of the overall
design of
the belt 10. 7"hese embodiments are trot illustrated but can easily be
visualized by
combining the framervor6:'s pattern of the ~ through-2,ir drying belt I Ob -
with the
framework's pattern of the forming belt I Oa in such a way that some of the
areas of
the "combined" belt comprise the pattern of the ti~rough-air crying belt 14b,
while
the other parts o.f the same "combined" belt campri,;e the~~ttern, Qf the
forming .belt
1 aa. . ~ - . .
As ahoy.-~ is 1=1Gs_ 3-3C, the individual, protuberances 40 may also have the
discrete deflection conduits 30 disposed therein and extending Fr~osn the web-
side
surface 21 to the backside surface 22 of the framework 20. The papermaking
belt 3 0
having the frrainpc~wo~lC '~0 ~eornprising the discrete pratubemnces 40 rs'lay
preferably
>, ;; . ;.. : ,
be utitiz~cd as the fo:rr.,:zig belt j~7a. The pap~rmaking, belt t 4 hav;ng
the framework
20 comprising the dixrete pmtuberartees 41~ is primarily disclosed in the
comt=ronly
assigned U.S. Patent 4,245,05 issued 9ep. 14, 1993 to Trakhan et al. and U.S.
Patent
5,527,428 issued yun. 18, 199=6 to Trokhan et al. Also, the papermaking belt
10 having
the discrete protuberances raised above the plane of the fabric may be made
according
to the European Patent Application 95105513.6, Publication l~To.: 0 6'77 di2
A2, filed
12.04.95, inventor Wendt et al.
The belt 10 is preferably air-pezmeable and liquid-pervious in at least one
direction, particularly the direction from the web-contacting side 11 to the
backside x2.
As used herein, the term "liquid-pervious" refers to the condition where a
liquid carrier
of a fibroa~ slurry may be transmitted thrQUgh the belt 10 without significant
obstruction. It is not, however, necessary, ar even desired, that the entire
surface area
oftl~e be2t IO be liquid-pervious. It is only necessary that the liquid
carrier be easily
removed from the slurry leaving on the web-contaatirig side 1 I of the belt 10
an
embryonic web of the paparmakizig fibers.
The web-sida surface 21 of the frarniewark 20 defuses the web-cozitacting side
I 1
of she papermaacing belt 10; and the machine-facing surface 22 of the
frarileWOrk 20
de~ir~es the backside t2 of the papermaking belt 1 O. Therefore, it also could
be
CA 02290494 1999-11-16
WO 98/53138 PCT/US98/10166
12
said that the discrete deflection conduits 30 and the essentially continuous
deflection
conduits 70 extend intermediate the web-contacting side 11 of the belt 10 and
the
backside 12 of the belt 10. The discrete deflection conduits 30 (or simply
"conduits
30") and the essentially continuous conduits 70 (or simply "conduits 70")
channel
water from the web b0 which rests on the web-side surface 21 of the framework
20
to the backside surface 22 of the framework 20 and provide areas into which
the
fibers of the web 60 can be deflected and rearranged to form dome areas --
comprising either discrete domes 65 (FIG. 4) or "continuous domes" forming a
first
region 64* (FIG. 4D) in the web 60. As used herein, the term "domes" indicates
elements of the web 60 formed by the fibers deflected into the deflection
conduits
30, 70. The domes 65 generally correspond in geometry and -- during the
papermaking process -- in position to the deflection conduits 30, 70 during
the
papermaking process. By conforming to the deflection conduits 30, 70 during
the
papermaking process, the regions of the web 60 comprising the domes 65 are
deflected such that the domes 65 protrude outwardly and extend from the
general
plan of the web 60, thereby increasing a thickness, or caliper, of the web 60
in a Z-
direction. As used herein, the Z-direction is orthogonal to the general plane
of the
web 60 and the belt 20, as illustrated in several Figures of the present
Application.
Of course, if the papermaking belt 10 having an area of essentially continuous
conduits 70 is used, the domes 65 of the paper web 60 will comprise an
essentially
continuous dome region 65.
Now referring to FIGs. 1-1 C, the web-side surface 21 of the essentially
continuous resinous framework 20 defines the general plane of the belt 10, or
an X-
Y plane. Because the web-facing side 51 of the reinforcing structure 50 is
generally
parallel to the web-side surface 21, the web-facing side S1 may also be viewed
as
defining the X-Y plane. The Z-direction defined hereinabove is therefore the
direction perpendicular to the X-Y plane. The web-side surface 21 of the
framework
20 has a web-side network 21 * formed therein. Likewise, the backside surface
22 of
the framework 20 has a backside network 22* formed therein. Because the
discrete
conduits 30 extend between the web-side surface 21 and the backside surface 22
of
the framework 20, each of the discrete conduits 30 has a pair of openings: a
web-
side opening 31 and a backside opening 32. The web-side network 21 * formed in
the web-side surface 21 defines the web-side openings 31 of the conduits 30;
and the
backside network 22* formed in the backside surface 22 defines the backside
openings of the conduits 30.
Each discrete conduit 30 has walls 35 extending between the web-side surface
21 (or the web-side network 21 *) and the backside surface 22 (or the backside
7 _ .. _ _ . _. _ _ . ._v .______ __.
CA 02290494 1999-11-16
WO 98/53138 PCT/US98/10166
13
network 22*). As will be shown below, the walls 35 of the same conduit 30 may
form different angles relative to the Z-direction. Each discrete conduit 30
has an
axis 33. As used herein, the "axis 33" of the conduit 30 is an imaginary
straight line
connecting the center C 1 of the web-side opening 31 and the center C2 of the
backside opening 32. The center C I of the web-side opening 31 is a center of
an X-
Y area of the opening 31, i.e., a point of an X-Y plane of the opening 31,
which
point coincides with the center of mass of a thin uniform distribution of
matter over
this X-Y plane of the opening 31. Analogously, the center C2 of the backside
opening 32 is the center of an X-Y area of the opening 32. One skilled in the
art will
readily recognize that if the opening 31 comprises a figure that is
bilaterally
symmetrical relative to an axis parallel to at least one of the X-Y
directions, then in a
Z-directional (i.e., vertical) cross-section perpendicular to that at least
one of the X-
Y directions, the center C 1 of the web-side opening 31 will be positioned in
the
middle of a web-side cross-sectional dimension "d" of the web-side opening 31
(FIGs. 1 A and 1 C). Likewise, if the opening 32 comprises a figure that is
bilaterally
symmetrical relative to an axis parallel to at least one of the X-Y
directions, then in a
Z-directional cross-section perpendicular to that at least one of the X-Y
directions,
the center C2 of the backside opening 32 will be positioned in the middle of a
backside cross-sectional dimension "e" of the backside opening 32 (FIGS. 1 A
and
1C). For example, in the embodiment shown in FIGs. l-1B, the web-side opening
31 of the conduit 30 comprises a diamond-shape figure bilaterally symmetrical
relative to an axis "md" parallel to the machine direction MD. In the Z-
directional
cross-section perpendicular to MD (or, in other words, in the "vertical CD
cross-
section") the center C1 of the web-side opening 3I is positioned in the middle
of the
web-side CD cross-sectional dimension "d," as best shown in FIG. 1 A. The
backside opening 32 also comprises a diamond-like figure bilaterally
symmetrical
relative to an axis {not shown) parallel to MD. In the Z-directional cross-
section
perpendicular to MD (or, in the "vertical CD cross-section"), the center C2 of
the
backside opening 32 is positioned in the middle of the backside CD cross-
sectional
dimension "e," as best shown in FIG. 1 B. The diamond-like openings 31 and 32
of
the conduits shown in FIGs. 1-1C are also bilaterally symmetrical relative to
an axes
"cd" parallel to the cross-machine direction CD. Therefore, analogously to the
"d"
and "e" discussed hereabove, in the Z-directional cross-section perpendicular
to CD
{or in the "vertical MD cross-section"), the centers C 1 and C2 of the
openings 31
and 32, respectively, are positioned in the middle of their respective MD
cross-
sectional dimensions "dl" and "el", as illustrated in FIG. IB. It should be
carefully
noted that the web-side openings 31 need not be identical to the corresponding
_ _-___
CA 02290494 1999-11-16
WO 98/53138 PCT/US98110166
14
backside openings 32, nor the web-side openings 31 need have the same general
shape (for example, circle, or diamond-like shape) as the backside opening 32.
According to the present invention, the web-side openings 31 are off set
relative to the backside openings 32 within the X-Y plane and in at least one
direction which is perpendicular to the Z-direction. One skilled in the art
will
readily recognize that there are infinite directions perpendicular to the Z-
direction
(or "X-Y directions"), all of which are included in the scope of the present
invention.
However, for clarity and convenience of illustrating the present invention,
the
present invention is discussed primarily in the context of the mutually
perpendicular
machine direction MD and cross-machine direction CD.
In papermaking, the machine direction MD indicates that direction which is
parallel to the flow of the web 60 (and therefore the belt 10) through the
papermaking equipment. The cross-machine direction CD is perpendicular to the
machine direction MD and parallel to the general plane of the belt 10. Both
the
machine direction MD and the cross-machine direction CD can be viewed as
parallel
to the X-Y plane. Consequently, the Z-direction is perpendicular to both the
MD
and the CD.
FIGs. 1 A and 1 C show that the web-side openings 3 I are off set relative to
the
corresponding backside openings 32 in the cross-machine direction CD. In FIGs.
1 A and I C a dimension of an off set is indicated by the symbol "T." As used
herein,
the "off set" in the context of the conduit 30 or a protuberance means the
distance
between the center C I of the web-side opening 31 and the center C2 of the
backside
opening 32 measured in, or geometrically projected to, the X-Y plane. If the
web-
side opening 31 is off set relative to the backside opening 32 in a direction
other
than either the MD or the CD, it still may be convenient to define the off set
in the
MD and the CD, as mutually perpendicular projections of a real dimension of
the
off set to the corresponding MD cross-section and CD cross-section,
respectively.
Therefore, as used herein, the "MD off set" indicates a projection of the
actual off
set to the MD. Likewise, the "CD aff set" indicates a projection of the actual
off set
to the CD.
FIGs. 1-1 B and 1 C schematically show various embodiments of the
papermaking belt 10 of the present invention, comprising the framework 20
which
has the discrete conduits 30 therein. In FIGs. 1-1B, the web-side openings 31
are
off set relative to the backside openings 32 in the cross-machine direction CD
(FIGs.
1 and lA). The dimension T and an angle Q formed between the axis 33 and the
Z-direction define the CD off set of the web-side opening 31 relative to the
backside
opening 32 of the conduit 30.
CA 02290494 1999-11-16
WO 98/53138 PCT/US98/10166
If the web-side cross-sectional dimension "d" is equal to the backside cross-
sectional dimension "e" in a Z-directional (vertical) cross-section parallel
to one of
the X-Y directions, the opposing walls 35 of the conduit 30 are mutually
parallel in
that X-Y direction, and the conduit 30 is said to be non-tapered in that X-Y
direction. Conversely, if the web-side cross-sectional dimension "d" is not
equal to
the backside cross-sectional dimension "e" in a Z-directional cross-section
parallel to
one of the X-Y directions, the opposing walls 35 are not mutually parallel in
that X-
Y direction, and the conduit 30 is said to be tapered relative to the axis 33
in that X-
Y direction. If the web-side cross-sectional dimension "d" is greater than the
backside cross-sectional dimension "e" in a Z-directional cross-section
parallel to
one of the X-Y directions, the conduit 30 is negatively tapered in that X-Y
direction.
Conversely, if the backside cross-sectional dimension "e" is greater than the
web-
side cross-sectional dimension "d" in a Z-directional cross-section parallel
to one of
the X-Y directions, the conduit 30 is positively tapered in that X-Y
direction: For
example, assuming that in FIG. lA, the web-side CD cross-sectional dimension
"d"
is greater than the backside CD cross-sectional dimension "e," the conduit 30
shown
in FIG. 1 A is negatively tapered in CD. Analogously, the same conduit 30
shown in
FIG. 1B is negatively tapered in the MD if dl>d2.
While it is not necessary, it is preferred that the discrete conduits 30 be
negatively tapered in both the machine direction MD and the cross-machine
direction CD. It should be carefully noted that while the embodiment
illustrated in
FIGS. 1-1 C comprises the framework 20 having the discrete conduits 30 which
are
tapered in both the mutually perpendicular MD and CD, an embodiment is
possible,
in which the discrete conduits 30 are tapered only in one of the MD or CD.
This
embodiment can easily be visualized by one skilled in the art by assuming that
the
dimensions "d" and "e" in FIG. lA are equal, and the dimensions "dl" and "el"
in
FIG. 1 B are not equal (i. e., d=e, and d 1 >e 1 ). Then, the discrete
conduits 30 will be
tapered in the MD (FIG. 1B) and non-tapered in the CD (FIG. lA). An embodiment
(not shown) is also possible, while not preferred, in which the conduits 30
are
negatively tapered in one of the X-Y directions, and are positively tapered in
the
other of the X-Y directions.
Another way of defining the tapered conduits 30 is illustrated in FIG. 1 C. In
FIG. 1 C, the Z-direction and the axis 33 of the conduit 30 form the angle Q
therebetween. The web-side CD cross-sectional dimension "d" is greater than
the
backside CD cross-sectional dimension "e." Therefore, an angle Q 1 formed in
the
CD cross-section between the Z-direction and a wall 35a of the conduit 30 is
greater
CA 02290494 1999-11-16
WO 98/53138 PCT/US98/10166
16
than an angle Q2 formed in the CD cross-section between the Z-direction and a
wall
35b of the conduit 30, opposite to the wail 35a in the cross-section.
FIGS. 2-3C illustrate other embodiments of the papermaking belt 10 of the
present invention. In the embodiments shown in FIGS. 2-3C, the resinous
framework 20 of the belt 10 comprises a plurality of discrete protuberances
40,
preferably forming a patterned array. The plurality of protuberances 40 is
joined to
the reinforcing structure 50 and preferably comprises individual protuberances
40
joined to and extending outwardly from the web-facing side 51 of the
reinforcing
structure 50. In the embodiments illustrated in FIGS. 2-3C, the web-facing
side 51
of the reinforcing structure defines the X-Y plane. Each protuberance 40 has a
top
surface 41, a base surface 42 opposite the top surface 41, and walls 45
spacing apart
and interconnecting the top surface 4I and the base surface 42. The plurality
of the
top surfaces 41 define the web-side surface 21 of the framework 20; and the
plurality
of the base surfaces 42 define the backside surface 22 of the framework 20.
As illustrated in FIGs. 2 and 2A, the plurality of protuberances 40 are
arranged
such thatthe protuberances 40 are preferably encompassed by and adjacent to
the
area of essentially continuous conduits 70 which extends from the top surfaces
41 of
the protuberances 40 to the web-facing side 51 of the reinforcing structure
50. As
used herein, the "area of essentially continuous conduits 70" defines an area
between
the adjacent protuberances 40 into which the fibers of the web 60 can deflect
during
the papermaking process according to the present invention. The area of
essentially
continuous conduits 70 has a defined flow resistance which is dependent
primarily
upon the pattern, size, and spacing of the individual protuberances and of the
reinforcing structure S0. In the preferred embodiment, each protuberance 40 is
substantially equally spaced from the adjacent protuberance 40, providing an
essentially continuous conduit 70 preferably having substantially uniform flow
resistance characteristics. If desired, the protuberances 40 may be clustered
together
so that one or more protuberances 40 is unequally spaced from an adjacent
protuberance 40.
The web-facing side 51 of the reinforcing structure 50 has an essentially
continuous web-facing network 51 * formed therein and defined by the area of
essentially continuous conduits 70. Preferably, the protuberances 40 are
distributed
in a non-random repeating pattern so that the fibers deposited onto the
essentially
continuous web-facing network 51 * around and between the protuberances 40 are
distributed more uniformly throughout the web-facing network 51 *. More
preferably, the protuberances 40 are bilaterally staggered in an array.
CA 02290494 1999-11-16
WO 98/53138 PCT/US98110166
I7
The belt 10 of the present invention is essentially macroscopically
monoplanar. As used herein, the requirement that the belt IO is "essentially
_ macroscopically monoplanar" refers to the overall geometry of the belt 10
when it is
placed in a two-dimensional configuration and has, as a whole, only minor and
tolerable deviations from the absolute planarity, which deviations do not
adversely
affect the belt's performance. The possible pre-determined differences in
height
among the protuberances 40 are considered minor relative to the overall
dimensions
of the belt 10 and do not affect the belt 10 being macroscopically monoplanar.
Each protuberance 40 has an axis 43. Analogously to the axis 33 of the
discrete conduit 30 defined in great detail above, the axis 43 of the
individual
protuberance 40 is an imaginary straight line connecting a center P1 of the
top
surface 4I and a center P2 of the base surface 42 (FIG. 2A). The center PI of
the
top surface 41 is a center of the top surface 41, i.e., a point of the top
surface 41,
which point would coincide with the center of mass of a thin uniform
distribution of
matter over this top surface 41. Analogously, the center P2 of the base
surface 42 is
a center of the base surface 42. By analogy with the discrete conduits 30, if
the top
surface 41 comprises a figure that is bilaterally symmetrical relative to an
axis (not
shown) parallel to at least one of the X-Y directions, then in a Z-directional
(i.e.,
vertical) cross-section perpendicular to that X-Y direction, the top surface
center P 1
will be positioned in the middle of a cross-sectional dimension "f' of the
area of the
top surface 41, as shown in FIG. 2. Likewise, if the base surface 42 comprises
a
figure that is bilateralIy symmetrical relative to an axis (not shown)
parallel to at
least one of the X-Y directions, in a Z-directional cross-section
perpendicular to that
X-Y direction, the base surface center P2 will be positioned in the middle of
a cross-
sectional dimension "g" of the area of the base surface 42.
In accordance with the present invention, the Z-direction and the axes 43 of
at
least some of the protuberances 40 form an acute angle S therebetween, as
shown in
FIG 2A. The top surfaces 4I of at least some of the protuberances are off set
relative to the corresponding base surfaces 42 of the same protuberances
within the
X-Y plane and in at least one direction which is perpendicular to the Z-
direction.
In FIGs. 2 and 2A, the top surfaces 41 are off set relative to the base
surfaces
42 in the cross-machine direction CD. An X-Y distance "V" between the top
surface
center P 1 and the base surface center P2, and an angle S formed between the
axis 43
and the Z-direction define the off set of the top surface 41 relative to the
base
surface 42.
If the top surface cross-sectional dimension "f' is equal to the base surface
cross-sectional dimension "g" in a Z-directional (vertical) cross-section
parallel to
CA 02290494 1999-11-16
WO 98/53138 PCT/US98/10166
18
one of the X-Y directions, the opposing walls 45 are mutually parallel, and
the
protuberance 40 is non-tapered in that X-Y direction. Conversely, if the top
surface
cross-sectional dimension "f' is not equal to the base surface cross-sectional
dimension "g" in a Z-directional cross-section parallel to one of the X-Y
directions,
the opposing walls 45 are not mutually parallel in that X-Y direction, and the
protuberance 40 is tapered relative to the axis 43 in that X-Y direction. If
the top
surface cross-sectional dimension "f' is smaller than the base surface cross-
sectional
dimension "g" in a Z-directional cross-section parallel to one of the X-Y
directions,
the protuberance 40 is positively tapered in that X-Y direction. If the top
surface
cross-sectional dimension "f' is greater than the base surface cross-sectional
dimension "g" in a Z-directional cross-section parallel to one of the X-Y
directions,
the protuberance 40 is negatively tapered in that X-Y direction. For example,
assuming that in FIG. 2A, the top surface cross-sectional CD dimension "f' is
smaller than the base surface cross-sectional CD dimension "g," the
protuberances
40 shown in FIG. 2A are positively tapered in CD.
While it is not necessary, it is preferred that if the framework 20 comprising
the tapered discrete protuberances 40 is to be utilized, the discrete
protuberances 40
be positively tapered in both the machine direction MD and the cross-machine
direction CD. However, the embodiment is possible, in which the discrete
protuberances 40 are tapered only in one of the MD and CD.
Referring now to FIGS. 3 and 3A, the plurality of discrete protuberances 40
may have a plurality of discrete deflection conduits 30 therein. The discrete
deflection conduits 30 extend from the web-side surface 21 to the backside
surface
22 of the framework 20, or, in other words, from the top surfaces 41 to the
base
surfaces 42 of the protuberances 40, because, as has been explained
hereinabove,
the plurality of top surfaces 41 form the web-side surface 21 of the resinous
framework 20, and the plurality of base surfaces 42 form the backside surface
22 of
the framework 20. Preferably, each individual protuberance 40 has one discrete
conduit 30 extending from the top surface 41 to the base surface 42.
As has been described hereinabove, each discrete conduit 30 has the web-side
opening 31 and the backside opening 32. The web-side openings 31 are
preferably
off set relative to the corresponding backside openings 32 in one of the X-Y
direction. In the belt 10 of the present invention, having the framework 20
comprising the discrete protuberances 40 which have the discrete conduits 30
therein, the off sets of the protuberances 40 are preferably, while not
necessarily,
coincidental with the off sets of the conduits 30 disposed in the
corresponding
protuberances 40. As shown in FIG. 3A, the axes 33 of the discrete conduits 30
are
CA 02290494 1999-11-16
WO 98153138 PCTIUS98/10166
19
preferably coincidental with the axes 43 of the protuberances 40, and the
angles Q
formed by the axes 33 and the Z-direction are preferably equal to the
corresponding
angles S formed by the axes 43 and the Z-direction. In FIG. 3A, the
protuberances
40 are positively tapered, and the discrete conduits 30 disposed in the
protuberances
40 are negatively tapered.
An embodiment (not shown) is possible, although not preferred, in which the
axis 33 of the discrete conduit 30 is not coincidental with the axis 43 of the
protuberance 40, and the angle Q formed by the axis 33 and the Z-direction is
not
equal to the angle S formed by the axis 43 and the Z-direction. The respective
off
sets of the protuberance 40 and the discrete conduit 30 may not be equal in
the latter
case.
The flow resistance of the discrete conduits 30 through the protuberance 40 is
different from, and typically greater than, the flow resistance of the
essentially
continuous conduits 70 between adjacent protuberances 40. Therefore, when the
belt 10 having both the discrete conduits 30 and the essentially continuous
conduits
70 is utilized as a forming belt 10a, typically more of the liquid carrier
will drain
through the continuous conduits 70 than through the discrete conduits 30, and
consequently, relatively more fibers will be deposited onto the areas of the
reinforcing structure 50 which are subjacent to the continuous conduits 70
(i.e., the
web-facing network 51 *) than onto the areas of the reinforcing structure 50
which
are subjacent to the discrete conduits 30.
The essentially continuous conduits 70 and the discrete conduits 30,
respectively, define high flow rate and low flow rate zones in the belt 10.
The initial
mass flow rate of the liquid carrier through the continuous conduits 70 is
preferably
greater than the initial mass flow rate of the liquid carrier through the
discrete
conduits 30.
It should be recognized that no liquid carrier will flow through the
protuberances 40, because the protuberances 40 are impervious to the liquid
carrier.
However, depending upon the elevation of the top surface 41 of the
protuberances
40 relative to the web-facing side 51 of the reinforcing structure 50 and the
length of
the cellulosic fibers, cellulosic fibers may be deposited on the top surfaces
41 of the
protuberances 40.
As used herein, the "initial mass flow rate" refers to the flow rate of the
liquid
carrier when the liquid carrier is first introduced to and deposited upon the
forming
belt 10a. Of course, it will be recognized that both flow rate zones will
decrease in
mass flow rate as a function of time as the discrete conduits 30 or the
essentially
continuous conduits 70 become obturated with cellulosic fibers suspended in
the
CA 02290494 2004-03-04
Mar-04-04 04:31pm From-511~BAS LTD 416595 1306 T-1t3 P.01T/02T F-124
zo
liquid carrier attd retained by the belt 10a. The difference in flow
resistance between
the discrete conduits 30 and the continuous conduits ?0 pro~rides a nxeans
~'or
retaining differem basis weights of cellulosic fibers in a pattern in the
different zones
of the belt 1 Oa. .
This difference in flow rates through the zones is referred to as "staged
draining," in reco~ition that a step discontinuity exists between the initial
flow rate
of'the liquid carrier through the high flow rate zones and the law flow rate
zones.
The more detailed description of the staged draining arid its benefits tnsy:be
found in
' the commonly assigned T1.S. Patent 5,245,023 referenced above. .
Tlre .papermaicing belt 10 of the present inventi4rx maybe made according to
the method comprising the following Steps. ,
First, an apparatus fur generating curing radiation should bc-provided. One
emt~odi.rrzt of the apparatus for generatircg.curing radiation is art
apparatus 80 for ~
ge»erating curing radiation R in at least a first radi:~t~r.,g direction U1.
The agparacus
80 schernatifiatly shown in FIG. 5 comprises two primary elements_ an elongate
. reflector 82 and ~an~ elonga:z soeuee of radiation 8S. Several embodiments
of the .
' apparatus 80 far generating curing radiation R are disclosed ~n the commonly
assigned co-pending Application entitled "Apparatus far Gexaerating ~onaralied
,
' ' Radiation for Curing Photosensitive I~.esin" Bled in the name of Trokhan
on the
sane date as the present application.
'Then, a liquid photosensitive resin should be provided. The suitable
photosensitive resin is disclosed in the commonly assigned'1J.S. patent
5,514,523,
issued ozt Dec. 20, 1993 to P.D. Trakhan et al:
The next step is prnviding a farming unit 87 having a working surface. 88.
The forming wnit 87 should be capable of receiving the liquid photosensitive
resin.
The next step is providing the air-permeable reinforcing structure 50
described
hereinabove, If the preferred papermaking belt 10 is to be manufactured in the
form
of endless belt, the reinforcing structure 50 should also be an endless belt.
It should
be noted that the step afpraviding the reinforcing structure 50 is necessary
for the belt
1 O having the framework 2Q which is comprised of the plurality of discrete
protuberances 40. In the case of manufacturing the belt 1fJ comprising the
essentially
continuous $amework 20, the reinforcing structure 50 is not necessary,
although highly
preferred.
CA 02290494 2004-03-04
Mar-04-04 D4:32pm From-SI~BAS LTD 416696 T306 T-1T8 P.O16/02t F-124
21
If the reinforcing structure 50 is to be utilized, the next steps are bringing
at
least a portion of the machine-facing side 5? of the reinforcing structure SD
into
contact with the working surface 88 of the forming unit $0, and applying a
coating
of t'Se liquid photosensitive resin to at least the web-facing side 51 of the
reinforcing
structure 50. The Coating has a pre-selected thickness, and after the costing
is
applied to the reinforcing structure 50, the coating farms a >;;rst swface~25
and a
second surface 27 opposite the first surface 25. After the process of eurirtg
is
complete, the first surface 25 will farm the web-side surface 21 afthe
framework 20.
and the second surface 37 will form the backside surface 22 of the framework
20.
The steps of bridging a 'portion of the machine-facing side 52 of the
reinforcing
structure 30 into contact with the working surface 88 and applying a coating
~of the
resin to the web~facing side 51 of the reinforcing Structure 50 are described
in
greater detail in the above-mentioned patent 5,514,523.
... . If the,r~einfarcing structure 50 i5 no~ tv br ~L~ilized, tlae liquid
photosensitive
resin may simply be disposed in the forming unit A f thereby forming~a
coating, of the
resin of a pr::-selected thickness, the coating having the .first surface ZS
and the
second surface 27 opposite the first surface 25_
After the. c oating of the liquid photosensitive resin has been formed (with
ar
without the reinfoa;:irrg structure 50), the next step is disposing the
forming unit 87
codtaiaing the co~~ti-:g of the liciuid photps~rtsitive resin, ixs the first
r2w;toting
direction U 1 such that the first surface 25 of the coating anc! the first
radiating
direction U 1 form an acute angle W therebetween. This step rnay be
accomplished
by positioning the coating of the rrsin as schemasicalty shown in FIG. 5A. If
desired., the angle of incidence of the curing radiation rnay be parallri to
the axis
thmugh the cotlitnator 90 (1~IGs. 5 and SA),
T'he c,~ Kcal point is that the resin coating is rrtaintained in acute angular
' relationship with the direction of the radiation during the curing process.
The
angular relationship may be accomplished by adjusting either the~position of
the
resin or the sklrection of the radiation, so that perpendicularity is avoided
and 3n
acute angle ootained.
Alternatively or additionally, this step may be accomplished by utilizing ata
apparatus of controlled radiation HO* schematically shown in FfG. SB.
The apparatus of controlled radiation 80* schEmatically shown In FIG_ 5i3
comprises
three sections 82: 82a, 8x17, 82c. The section 82b is movably
CA 02290494 1999-11-16
WO 98/53138 PCTIUS98/10166
22
connected to the section 82a, and the section 82c is movably connected to the
section 82b. Each section 82 {82a, 82b, 82c) comprises a plurality of
reflective
facets 83 {83a, 83b, 83c, respectively). Each individual reflective facet 83
is
independently adjustable in the cross-section. The source of radiation 85 is
movable
in the cross-section.
The combination of independent adjustability of the individual reflective
facets
83 and the independent adjustability of the individual sections 82 combined
with the
movability of the source of radiation 85 allows to direct the curing radiation
generated by the apparatus 80* in at least one pre-determined radiating
direction in
the cross-section. In FIG. SB, the apparatus 80* directs the curing radiation
in the
first radiating direction U1, a second radiating direction U2, and a third
radiating
direction U3.
FIG. SC shows another embodiment of the apparatus of controlled radiation
80*. The apparatus 89 shown in FIG. SC comprises several sources of radiation,
preferably bulbs, 85. Each bulb 85 has its longitudinal direction essentially
perpendicular to the machine direction MD. Each bulb 85 has its own
collimating
element 90 disposed between the bulb 85 and the photosensitive resin being
cured.
The collimating elements 90 are disposed such that the curing radiation
emitted by
each bulb has its own predetermined direction (U1, U2, U3, as schematically
shown
in FIG. SC). Subtractive walls 89 are preferably provided to restrict the
mutual
interference between the portions of the curing radiation having different
directions
U1, U2, U3.
The embodiments of the apparatus 80* shown in FIGs. SB and SC
prophetically produce the belts 10 having sophisticated three-dimensional
designs of
the resinous framework 20. In FIGS. SB and SC, for example, the resin being
cured
by the apparatus 80* will form the framework 20 having three zones H1, H2, and
H3
distinguished by relative "angled" orientations of the discrete conduits 30
(or the
discrete protuberances 40 in the case of the forming belt 1 Oa).
The next step is providing a mask 96 having opaque regions 96a and
transparent regions 96b. The purpose of the mask is to shield certain areas of
the
liquid photosensitive resin from exposure to the curing radiation R so that
these
shielded areas will not be cured, i.e., will remain fluid, and will be removed
after
curing is completed. The unshielded areas of the liquid photosensitive resin
will be
exposed to the curing radiation R to form the hardened framework 20. The
opaque
regions 96a and the transparent regions 96b define a pre-selected pattern
corresponding to a specific desired design of the resinous framework 20. If,
for
example, the belt 10 having a substantially continuous resinous framework 20
is to
CA 02290494 1999-11-16
WO 98153138 PCT/US98110166
23
be produced, the transparent regions 96b must form a continuous area generally
corresponding to the X-Y plane of the desired web-side network 21 * of the
framework 20.
The next step is positioning the mask 96 between the first surface 25 of the
resin coating and the apparatus 80 such that the mask 96 is preferably in
adjacent
relation with the first surface 25. The opaque regions 96a of the mask shield
a
portion of the coating from the curing radiation R, and the transparent
regions 96b
leave the other portions of the coating unshielded for the curing radiation R.
The next step is curing of the unshielded portions of the coating by exposing
the coating to the curing radiation R having an activating wavelength from the
apparatus 80 through the mask 96 to form a partially-formed belt, and leaving
the
shielded portions of the coating uncured.
The final step is removing substantially all uncured liquid photosensitive
resin
from the partially-formed belt to leave a hardened resinous structure. This
hardened
resinous structure forms a framework 20 having a web-side surface 21 formed by
the
first surface 25 being cured, and a backside surface 22 formed by the second
surface
27 being cured.
In the case of the belt 10 comprising a continuous framework 20, the
framework 20 has a plurality of discrete conduits 30 in the regions which were
shielded from the curing radiation R by the opaque regions 96a of the mask 96.
The
discrete conduits 30 extend between the web-side surface 22 (or the cured
first
surface 25) and the backside surface 27 (or the cured second surface 27), each
of the
conduits 30 having the axis 33 and the walls 35, the axes of at least some of
the
conduits and the Z-direction forming an acute angles therebetween, as has been
described in greater detail above.
In the case of the belt 10 having the framework 20 comprising the plurality
of discrete protuberances 40, the plurality of discrete protuberances 40
extends from
the reinforcing structure 50, each of the protuberances having the axis 43,
the base
surface 42, the top surface 41, and the walls 45 spacing apart and
interconnecting the
base surface 41 and the top surface 42. The plurality of the top surfaces 41
define
the web-side surface 21 of the resinous framework 20, and the plurality of
base
surfaces 42 define the backside surface 22 of the resinous framework 20. The
axes
43 of at least some of the protuberances 40 and the Z-direction form acute
angles
therebetween, as has been described in greater detail above.
The papermaking process which utilizes the papermaking belt 10 of the
present invention is described below, although it is contemplated that other
processes utilizing the belt 10 may also be used. By way of background it
should be
CA 02290494 2004-03-04
~lar-04-04 04:32pm Frvm-SII~AS LTD 416596 2306 T-1t6 P.018/02T F-124
24
appreciated that the belt 10 comprising the resinous framework 20 which is
substantially Cdntinuous is primarily utilized as a through-air drying belt i
Ob, while
the bett~ 10 comprising the framework 20 in the form of the plurality of
discrete
protube~.rtces 40 ~ is primarily utilised as a fotttxing wire 1 Via, as
schematically
illustrated in FICr_ b_ It cls~es real exclude, however, the alternative uses.
i. e., that the
belt 10 comprising the substantially continuous resinous framework 20 maybe
used
as a forming belt I Qa, and the belt 10 comprising the resinous framework ?0
in the
form of the plurality of discrete protuberances 40 may be used as a through-
air
drying belt t Ob.
The overall papetmaking process which uses the papermaking belt 10 of the
present invention comprises a number of steps or operations which occur in the
general sequence as noted below. It is to !ae understood, however, that the
steps
described below are intended to assist a reader in understanding the process
of the
present inverAtion, and that the invention is nc~x irmite~ to processes with
o:xly a
c~errain number or ~:~rrangemtnt of steps. In ibis regard, it is noted that it
is possible
to combine at least sortie of the following steps so that they are performed
cortcturently. Likewise, it is possible to separate at least ststrte of the
following steps
-into xwo or more step, without departing from the scope of this inventit~n.
FIG. 6 is a simplifit~d, schematic repcesentatio~n of one embodiment of a
continuous paper~r~aking ~machitte useful in the practice of the pap~:rcnaking
process
of the present invention. As has been defined above, the papermaking belt I 4
of the
present invention includes the forming belt l0a and the tluoetgh-air drying
belt 10b,
bout shown in the preferred form of endless belts in FIG. 6.
The first step i$ to provide a plurality of cellulosie fibers entrained ~in a
liquid
carrier, or, in other words, an aqt~us dispersion of papermaking Ethers. The .
ceilulosic fibexs a:z not dissolved in the Iicluid earner, but merely
suspended therein.
The equipment for preparing the aqueous dispersion of papermaking fibers is
well-
known in the pxpetrnakittg art and is therefore not shown in FIG. 6_ The
aqueous
dispersion of paFertnalciieg fibers is provided to s headbox IS. A single
tteadbox is
shown in FIG. 6. However, it is to be tutderstaad that there may be multiple
headbaxes in alternative arrangements of the paperm-airing process of the
present
invention. The headlvox(es) and the equipment for preparing the aqueous
dispersion
of papermaking, fibers are preferably of the type disclosed in U.S. Patent No.
3,9t34,77I, issued to Morgan and Rich on November 30, 1976. The preparation of
the
aqueous dispersion and the characteristics of the aqueous dispersion are
described in
greater detail in 'U.S. patent
CA 02290494 2004-03-04
tlar-04-04 04:33pm From-SIkBAS LTD 416696 T306 T-1TB P.020/02t F-124
4.,529,480 issued to Trokham on July 1~, 1985:
The adueous dispersion of papermakiizg fibers supplied by the headbox I S is
delivered to a forming belt. such as the ~osming belrs ' as of the,Rresent
invention. for
carrying out't~e second step bf tlxe prapermaking process. The forming belt i
Oa is
supported by a bireast roll 1$a and a plurality of return rolls designated as
I 8b and
t 8c. The forming wire I Oa is propelled in the direction indicated by the
directional
arrow A by a conventional drive means v.~ell known to one skilled in the art
and
therefore not shown in FIG 6. , There may also be associated with ~ the
papermaking
machine shown in FhL"s. 6 optional auxiliary units and, devices which one
commonly
associated with papermaking machines and with forming t5elts, including:
fornting
boards, hydrofoils, vacuum boxes, tension roils, support rolls, wire cleaning
showers, and the like, which are conventional and welt-known in the
papermaking
art . and therefore also not shown in FhG. 6.
The preferred s Earn. ing belt l0a is the macroscopically manoplanar belt
;r. ,
comprising the air-pernxeable reinforcing structure SQ and the resinous
framework
~r~ joined to the reinforcing structutr 50. ~ As has. been described above,
the
.,;,.
reinforcing structure 50 has the web-facing side S t and the mx:c>°Line-
facing side SZ
opposite the machine-fuemg_sidc 51. .T'te web-facing side 51 defines rye X-Y
plane
of the far._~.iing belt l0: this X-Y pfanc being_perpendicuiar to the ~-
cli~ection. The
framework 20 is comprised of the plurality of ~discr~ete protuberances 40
joined to
and extending from the reinforcing structure 50. F~ch of the protuberances 40
has
the top. surface 41, the base surface 42, the walls 45 sparing apart and
intereonnertittg the top surface 41 and the base surface 42, and the axis 43
connecting the center of the top surface 4 i and the center of the base
surface 42_
The plwrality~ of top surfaces 42 define the web-side ,surface 3',, and the
plurality of
base surfaces 4~ define the ldackside stufacc 22 of the framework 20. Ln
accordance
with the present invention, the axes 43 of at least some of the protuberances
40 ~ and
the Z-direction,form acute angles S theri~betweett.
If the fcirning belt 10a has the area of essentially cony;taous conduits 70
and
the phuality of discs~t~e deflection condu~ets 30 disposed in the
protuberances 40, the
belt l0a has high flow rate liquid pervious zones and low flow rate liquid
pervious
zones respectively defined by the cssetttially continuous deflection conduits
70 and
the discrete conduits ~0_ The liquid carrier and entrained cellulosic fibers
are
deposited onto the forming belt 10a illustrated in f=igure 6. The liguid
carrier is
drained through the fotTrsing belt tOa in two simultaneous stages, a high flow
rate
stage and a low ~1aw rata stage. In the high flow rate stage, the Iiguid
carrier drains
CA 02290494 2004-03-04
h~lar-04-04 04:33pm From-SII~BAS LTD 416896 T306 T-1T8 P:021/62T F-124
26
through the liquid pervious high flow rate zones at a given initial flow rate
until
vbturation occurs (or the liquid carrier is na longer introduced to this
portion of the
forrning~belt 10). In the low flow rate. stage, the liquid carrier drains
through low
flow rate zones of the forming tae.lt I Oa at a given initial fl4w ~.te which
is less than
the initial flow rate through the high flaw rate zones.
As has been noted above, the high flow rate liquid pervious zones and the low
flow rate liquid pervious zones in the belt l0a decrease as a function of
time, due to
expected obturatian of moth ztmes. It is believed that the low flow rate zones
may
obtuxrate before the high flow rate zones obturate.
Without being bound by theory, the Applic2~nt believes that the first
occurring
zane obturation rnay be due to the lesser hydraulic radius and greater flow
resistance
of such zones, based upon factors such as the flow area, wetted perimeter,
shape and
distribution of the low flow rate zotlts, or may be due to a greater flow rate
through
such zone accompanied by a greater depiction of fbers. The Ivw fla~N ratf
z.~nes
may, for example. comprise discrete conduits 30 through the, protuber~artces
40,
w-hictt discrete Conduits 30 have a greater flow resistance than the
essentially
eontihuous conduits 7p between adjacent protuberances 40. It is important than
tote
ratio of the flow. rrsistances between the discrete conduits 30 and the
essentially
continuous condu:~s 70 be properly prapottioned. 'Ihe flow resistance of the
discrete
cQreduits 30 and the essentially ca~trtiriiuous conduits.70 rna~y be
determined by using
the hydraulic radius, as described in the eomrxaonly assigned U.S. Patent
5,527,428
referenced above.
"Ilte next steps are depositing the plurality of cellulosic papermaking fibers
suspended in a liquid carrier on the forming belt t0a and draining the liquid
carrier
through the farming belt thereby forming an embryonic web 60 of the
paperznalcing
fibers on the foaming belt l0a_ As used herein. the "embryonic web" is the web
of
fibers which is subjected to rearrangement on the forming belt, and.
preferably the
forming belt 10a of the present invention, dtuing the course of the
paperntaking
proccs.,s. The characte.~'.stics of the ea~t~tyonie web 60 and the various
possible
techniques .for forming the embryonic web 6U are described in the cortemonly
assigned U'.S. Pat~~nt 4,~2~,480. In the process shown in FIG. 6, the
embryonic web 60
is formed from the cellulosic ftbexs suspended in s. liquid carrier between
breast roll
18a and return roll 18b by depositing the cellulosic fibers suspended in a
Iiqtud carrier
onto the forming wire l0a and removing a portion of the liquid earner through
the belt
10a. ~orxveztt~ioxia! vacuttrn boxes, forming boards, hydx'ofoils, and tb.e
lil~e which are
not shown in FIG. 6 are useful in effecting the removal of liquid~carrier.
CA 02290494 1999-11-16
WO 98/53138 PCT/US98/10166
27
The embryonic web 60 formed on the forming belt l0a of the present
invention and shown in FIG. 4D has a first side 61 * and a second side 62*
opposite
the first side 61 *. The first side 61 * is that side which is associated with
the web-
contacting surface 11 of the belt 10a. When the belt 10 of the present
invention is
utilized as the forming belt 10a, the embryonic web 60 shown in FIG. 4D
comprises
a macroscopically planar and patterned first region 64* (corresponding to the
area of
essentially continuous conduits 70) preferably having a relatively high basis
weight,
and a second region 65* (corresponding to the area of discrete protuberances
40)
preferably having a relatively low basis weight. The first region 64*
comprises an
essentially continuous network; and the second region 65* comprises a
plurality of
discrete "angled" knuckles 65* extending from the first region 64* in at least
one
direction. This at least one direction (defined by an imaginary axis 63* of a
knuckle
of the second region 65) and the Z-direction form an acute angle L
therebetween
(corresponding to the acute angles S formed between the Z-direction and the
axes 43
of the conduits 40). The second region 65* is circumscribed by and adjacent to
the
first region 64*. The second region 65* comprising the discrete angled
knuckles
having a low basis weight preferably occur in a non-random repeating pattern
corresponding to the pattern of the plurality of discrete protuberances 40 of
the
forming belt 10a.
If the forming belt l0a has the essentially continuous conduits 70 and the
discrete conduits 30, the embryonic web 60 may comprise a third region 66*
preferably having an intermediate basis weight relative to the basis weight of
the
first region 64* and the basis weight of the second region 65*. The third
region 66*
occurs in a preferred non-random repeating pattern substantially corresponding
to
the low flow rate zones, i. e., the zones of the discrete conduits 30. The
third region
66* is juxtaposed with, and preferably circumscribed by, the second region
65*.
After the embryonic web 60 is formed, the embryonic web 60 travels with
the forming wire l0a in the direction indicated by the directional arrow A
(FIG. 6) to
be brought into the proximity of the through-air drying belt lOb. The
preferred
through-air belt lOb is described in great detail hereinabove. The through-air
belt
lOb is a macroscopically monoplanar papermaking belt comprising the resinous
framework 20 having the web-side surface 21 defining the X-Y plane, the
backside
surface 22 opposite the web-side surface 21, the Z-direction perpendicular to
the X-
Y plane, and the plurality of discrete deflection conduits 30 extending
between the
web-side surface 21 and the backside surface 22. Each of the conduits 30 has
the
axis 33 and the walls 35. In accordance with the present invention, the axes
33 of at
CA 02290494 1999-11-16
WO 98/53138 PCT/US98/10166
28
least some of the conduits 30 and the Z-direction form the acute angles Q
therebetween.
The next steps are depositing the embryonic web 60 to the web-side surface 21
of the resinous framework 20 of the through-air drying belt l Ob and applying
a fluid
pressure differential to the embryonic web 60 to deflect at least a portion of
the
papermaking fibers into the discrete deflection conduits 30 and to remove
water
from the embryonic web 60 into the discrete deflection conduits 30 thereby
forming
an intermediate web 60.
In the embodiment illustrated in FIG. 6, the through-air drying belt lob of
the
present invention travels in the direction indicated by directional arrow B.
The belt
l Ob passes around the return rolls 19c, 19d, impression nip roll 19e, return
rolls 19a,
and 19b. An emulsion distributing roll 19f distributes an emulsion onto the
through-
air drying belt lOb from an emulsion bath. The loop around which the through-
air
drying belt l Ob of the present invention travels also includes a means for
applying a
fluid pressure differential to the web 60, which means in the preferred
embodiment
of the present invention comprises vacuum pick-up shoe 17a and a vacuum box
17b.
The loop may also include a pre-dryer (not shown). In addition, water showers
(not
shown) may preferably be utilized in the papermaking process of the present
invention to clean the through-air drying belt l Ob of any paper fibers,
adhesives, and
the like, which may remain attached to the through-air drying belt lOb after
it has
traveled through the final step of the papermaking process. Associated with
the
through-air drying belt lOb of the present invention, and also not shown in
FIG. 6,
are various additional support rolls, return rolls, cleaning means, drive
means, and
the like commonly used in papermaking machines and all well known to those
skilled in the art.
When the through-air drying belt lOb of the present invention is utilized in
the papermaking process, the intermediate web 60 shown in FIGs. 4-4C comprises
a
macroscopically monoplanar, patterned, and essentially continuous network
region
64 preferably having relatively high density and a domes region 65 preferably
having relatively low density. The domes region 65 comprises a plurality of
discrete
domes 65, or 65a, 65b, 65c, protruding from, circumscribed by, and adjacent to
the
network region 63. Each of the domes 65 has an axis 63. The axes 63 of at
least
some of the domes 65 and the Z-direction form acute angles K (FIG. 4B) and
acute
angles M1 and M3 (FIG. 4C) therebetween.
The papermaking process of the present invention may also include an
optional step of pre-drying the intermediate web 60 to form a pre-dried web
60. Any
convenient means conventionally known in the papermaking art can be used to
dry
_...__._ _~ _ _ __ __ .
CA 02290494 1999-11-16
WO 98153138 PCT/US98/10166
29
the intermediate web 60. For example, flow-through dryers, non-thermal,
capillary
dewatering devices, and Yankee dryers, alone and in combination, are
satisfactory.
The next step in the papermaking process is impressing the web-side network
21 * of the resinous framework 20 into the pre-dried web 60 by interposing the
predried web 60 between the belt 10 and an impression surface to form an
imprinted
web 60 of papermaking fibers. If the intermediate web 60 is not subjected to
the
optional pre-drying step, this step is performed on the intermediate web 60.
The step of impressing is carried out in the machine illustrated in FIG. 6
when
the pre-dried (or intermediate) web 60 passes through the nip formed between
the
impression nip roll 19e and the Yankee drier drum 14. As the predried web 60
passes through this nip, the network pattern formed on the web-side network 21
* of
the framework 20 is impressed into the pre-dried web 60 to form an imprinted
web
60.
The next step in the papermaking process is drying the imprinted web 60. As
the imprinted web 60 separates from the belt 10, it is adhered to the surface
of
Yankee dryer drum 14 where it is dried to a consistency of at least about 95%
to
form a dried web 60.
The next step in the papermaking process is an optional, and highly preferred,
step of foreshortening the dried web 60. As used herein, foreshortening refers
to the
reduction in length of a dry paper web 60 which occurs when energy is applied
to
the dry web 60 in such a way that the length of the web 60 is reduced and the
fibers
in the web 60 are rearranged with an accompanying disruption of fiber-fiber
bonds.
Foreshortening can be accomplished in any of several well-known ways. The most
common, and preferred, method is creping schematically shown in FIG. 6. In the
creping operation, the dried web 60 is adhered to a surface and then removed
from
that surface with a doctor blade. As shown in FIG. 6, the surface to which the
web
60 is usually adhered also functions as a drying surface, typically the
surface of the
Yankee dryer drum 14. Generally, only the non-deflected portions of the web 60
which have been associated with web-side network 21 * on the web-contacting
side
11 of the papermaking belt 10 are directly adhered to the surface of Yankee
dryer
drum 14. The pattern of the web-side network 21 * and its orientation relative
to the
doctor blade will in major part dictate the extent and the character of the
creping
imparted to the web. If desired, the dried web 60 may not be creped.
The general physical characteristics of the paper web 60 which is made by the
process of the present invention utilizing the through-air drying belt l0a
having an
essentially continuous framework 20 are described in the aforementioned U.S.
CA 02290494 2004-03-04
liar-D4-04 D4:33pm From-SIIr~AS LTD 416686 1306 T-1T8 P.022/02T F-124
Patent 4,529,480 entitled "''Tissue Paper", which issued to ~'rokhan an 3~u13~
I6, 1.9$5:
'fhe plurality of domes 65 in the paper web 60 of the present invention,
however, will prophetically fatztt an "angled" pattern, due to the "angled"
positicm of
thG conduits 30 of the through-air drying belt 10 of the present invention. 1t
should
be understood that the steps of imprinting, drying, and - especially --
ereping may
interfere with the "angled" position of the domes 65. That is to say, the
processing
of the web 60 after it is separated fmm the through-air drying belt I Ob ~.~ay
affect the
overall configuration of the. domes 55 as well as the acute angles K (FI~'~_
4B) anii~
M 1. M3 (F1.f~r. 4C) formed between the Z-direction and the aces of the domes
55 in
such a way tlsat throe acute angles may not be ~t~al to the corresponding
angles Q
between the Z-direction and the axes 33 of the conduits 30. It is believed,
however,
that the paper vveb 50 according to the present invention will have the crass-
sectional
" ~ngled° Gatterrt of the domes ~5 generally following the cross-
sectional angled
pattern of the conduits 30 of the resinous framewor': ~~.
!=1Gs_ 4-.~C show one orophetie embodiment of the paper web b0 according tv
thr prrsen' ~avention_ Pmt~rabty, the domes 65 are disposed in a non-s~rcdom
and
repeating pattern which corresponds to the pattern of the diserett conduits 30
of the
resinous framework ~0 of the btlt 10. While r:~t being inte~:~..a .to be bound
by
theory. the~Applicar.' 1=;.lieves that tat paper 60 having the acutely angled
dorrrcs 65
is softer than the comparable paper ktaving domes generally perpendicular
relative to
,thr plane of the network region 64, because the acutely angled domes 65 are
believed to be more easily collapsible i3tart the generally perpendicularly
upstanding
domes. Moreover. it is believed that the angled domes G5 having a speeiftc pre-
determined direetiona) orientation rnay provide a benefit of facilitating a
distribution
of liquids is a desired dir~eetion. This property may provt to be very
beneficial if the
paper b0 is ustd in such disposable products as diapers, sanitary napkins,
wipes, and
the like.
For example, the paper web 6~ r~_~wn in 1~IG:~. 4 and 4C has three zones of
relative orientation: a first zone H1, the seGand zotve H~, and a third zone
H3_ As
best shov..t in FIGS. 4 and 4~, the first wne HI has the domes 65a oriented in
a first
direction hl, the second zone H2 has the dames 65b oriented in a second
direction
h~'. and the third gone H3 has the domes 55c oriented iut a third direction
h3_
Viewed in plane, the first direction hl and the second direction h2 are
directed
towards each other, and the third direction h3 is perpendicular to the first
and second
directions hl, h2.
