U.S. patent application number 10/713900 was filed with the patent office on 2004-08-19 for non-woven wet wiping.
Invention is credited to Horn, Drew, Smith, Peter R., Walton, Richard C..
Application Number | 20040161991 10/713900 |
Document ID | / |
Family ID | 23066315 |
Filed Date | 2004-08-19 |
United States Patent
Application |
20040161991 |
Kind Code |
A1 |
Walton, Richard C. ; et
al. |
August 19, 2004 |
Non-woven wet wiping
Abstract
A non-woven wet wipe product (22) comprising a sheet member, for
use with a wet wiping agent (32), (18), the product comprising a
segment of a non-woven self-supporting web (150) comprised of an
assemblage of fibers including synthetic thermoplastic fibers and
absorbent or adsorbent fibers, the non-woven web (150) being in a
permanent, dry-creped, heat-set condition defining a succession of
ridges (24) and grooves (26) in the overall body (30) of the web,
the constituent thermoplastic fibers of the sheet member having
been heat-set simultaneously during the imparting of the ridges and
grooves to the web, the heat-set condition of the dry-creped
thermoplastic fibers preserving the ridge and groove configuration
during prolonged presence in the web of the wet agent (32). The wet
wiping agent can be initially, prewet in the packaging, with liquid
disposed through the body and on the surface of the dry-creped,
heat-set sheet-form member and its constituent fibers. In this
case, the product is packaged in a stack within a liquid tight
container. In another case the wipes are packaged dry to be wet by
the user. Methods for making the products are also disclosed.
Whereas advantageous embodiments are formed by hydro entanglement,
other embodiments are formed using other non-woven forming
processes, including wet-laid techniques, etc.
Inventors: |
Walton, Richard C.; (Boston,
MA) ; Smith, Peter R.; (Sharon, MA) ; Horn,
Drew; (Weymouth, MA) |
Correspondence
Address: |
FISH & RICHARDSON PC
225 FRANKLIN ST
BOSTON
MA
02110
US
|
Family ID: |
23066315 |
Appl. No.: |
10/713900 |
Filed: |
November 5, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10713900 |
Nov 5, 2002 |
|
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PCT/US02/09329 |
Mar 26, 2002 |
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60278776 |
Mar 26, 2001 |
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Current U.S.
Class: |
442/327 |
Current CPC
Class: |
B32B 2262/04 20130101;
D04H 1/435 20130101; Y10T 442/60 20150401; D04H 1/492 20130101;
D04H 1/4258 20130101; B32B 27/32 20130101; D04H 1/495 20130101;
D04H 1/54 20130101; Y10T 442/20 20150401; D04H 1/49 20130101; Y10T
428/24355 20150115; D04H 1/558 20130101; Y10T 442/689 20150401;
A61K 8/0208 20130101; D04H 1/4291 20130101; B32B 2262/0276
20130101; B32B 2323/10 20130101; B32B 2262/0253 20130101; B32B
27/36 20130101; D04H 1/43835 20200501; B32B 2262/062 20130101; B32B
5/022 20130101; B32B 5/02 20130101; D04H 1/485 20130101; Y10T
428/24446 20150115; B32B 2367/00 20130101; B32B 2432/00 20130101;
B32B 2262/067 20130101; B32B 27/18 20130101; A61Q 19/00 20130101;
A61Q 1/14 20130101; B32B 27/12 20130101; D04H 1/4374 20130101; B32B
2307/726 20130101 |
Class at
Publication: |
442/327 |
International
Class: |
D04H 001/00 |
Claims
What is claimed is:
1. A non-woven wet wipe product (22) comprising a sheet member,
pre-wetted with a wet wiping agent (16), and disposed in a
fluid-proof package (18), the product comprising: a. a segment of a
non-woven self-supporting web (11, 120, 150) comprised of an
assemblage of hydroentangled fibers (8, 9) including synthetic
thermoplastic strength-providing fibers (8) and absorbent or
adsorbent fibers (9), b. the non-woven web (14) being in a
permanent, dry-creped, heat-set condition defining a succession of
ridges (24) and grooves (26) in the overall body (30) of the web,
the constituent thermoplastic fibers (8) of the sheet member having
been heat-set simultaneously during the imparting of the ridges and
grooves to the web, the heat-set condition of the dry-creped
thermoplastic fibers preserving the ridge and groove configuration
during prolonged presence in the web of the wet agent (16), c. the
wet wiping agent (16) being disposed through the body (30) and on
the surface of the dry-creped, heat-set sheet-form member and its
constituent fibers (8, 9).
2. A non-woven wet wipe product (22) comprising an adsorbent sheet
member adapted to be wetted with a wet wiping agent, the product
comprising: a. a segment of a non-woven self-supporting web (11,
120, 150) comprised of an assemblage of fibers (8, 9), that
includes synthetic thermoplastic fibers (8), b. the non-woven web
(14) being in a permanent, dry-creped, heat-set, volume-enhanced
condition, the constituent thermoplastic fibers (8) of the sheet
member having been heat-set simultaneously during the creping of
the web, the heat-set condition of the dry-creped thermoplastic
fibers preserving the volume-enhanced structure of the assemblage
during prolonged presence in the web of the wet agent (16),
3. The wet wipe product (22) of claim 1 or 2 in which the sheet has
been coarsely dry-creped, resulting in a coarse distribution of
ridge formations (24) in the sheet.
4. The wet wipe product of claim 1 or 2 in which there are between
about 8 and 25 heat-set ridges (24) per lineal inch of the web
(between about 3.1 and 9.8 ridges per linear cm).
5. The wet wipe product (22) of claim 1 or 2 in which there are
between about 8 and 15 heat-set ridges (24) per lineal inch of the
web (between about 3.1 and 5.9 ridges per lineal cm).
6. The wet wipe product (22) of claim 1 or 2 in which there are
between about 15 and 20 heat-set ridges (24) per lineal inch of the
web (between about 5.9 and 7.9 ridges per lineal cm).
7. The wet wipe product (22) of claim 1 or 2 in which there are
between about 20 and 25 heat-set ridges (24) per lineal inch of the
web (between about 7.9 and 9.8 ridges per lineal cm).
8. The wet wipe product (22) of claim 1 or 2 in which the sheet
member is comprised of between about 1/3 and 2/3 by weight
absorbent or adsorbent fibers (9) and between about 1/3 and 2/3 by
weight of synthetic thermoplastic, strength-imparting fibers
(8).
9. The wet wipe product (22) of claim 1 or 2 in which the sheet
member comprises about equal weight of the absorbent or adsorbent
fibers and the thermoplastic, strength-imparting fibers (8).
10. A wet wipe product of claim 1 or 2 in which the sheet member
comprises absorbent fibers that are strength members.
11. The wet wipe product (22) of claim 1 or 2 in which the
thermoplastic fibers (8) comprise PET (polyester).
12. The wet wipe product (22) of claim 1 or 2 in which the
thermoplastic fibers (8) comprise polypropylene.
13. The wet wipe product of claim 1 or 2 in which the thermoplastic
fibers are polyethylene.
14. The wet wipe product (22) of claim 1 or 2 in which the
absorbent or adsorbent fibers (9) are cellulosic.
15. The wet wipe product (22) of claim 14 in which the cellulosic
fibers comprise natural fibers.
16. The wet wipe product of claim 1 or 2 in which all of the fibers
are thermoplastic.
17. The wet wipe product (22) of claim 1 or 2 in which absorbent or
adsorbent fibers comprise rayon.
18. The wet wipe product (22) of claim 1 or 2 comprising fibers (8)
of PET and fibers (9) of wood pulp.
19. The wet wipe product (22) of claim 1 or 2 in which the web (11,
120, 150) comprises a spunlace web (120).
20. The wet wipe product (22) of claim 1 or 2 in which the wet
wiping agent (16) comprises an aqueous agent.
21. The wet wipe product (22) of claim 20 in which the wet wiping
agent (16) comprises one of a soap, a detergent, a solvent, a
cleaning, a window washing, a sanitizing, a biociding, a polishing,
an abrading and a neutralizing agent.
22. The wet wipe product (22) of claim 20 in which the wet wiping
agent (16) comprises one of an insect repellant, a paint solvent, a
paint remover, a finish remover, an oil solvent, a grease solvent,
a cosmetic remover, a makeup remover, a stain remover, a stain, a
paint, a varnish, a wax and a polish.
23. A package (18) comprising a face-to-face stack (21) of a
plurality of sheet members (22), each sheet member comprising: a. a
segment of a non-woven self-supporting web (11, 120, 150) comprised
of an assemblage of hydroentangled fibers (8, 9) including
synthetic thermoplastic strength-providing fibers (8) and absorbent
or adsorbent fibers (9), b. the non-woven web (14) being in a
permanent, dry-creped, heat-set condition defining a succession of
ridges (24) and grooves (26) in the overall body (30) of the web,
the constituent thermoplastic fibers (8) of the sheet member having
been heat-set simultaneously during the imparting of the ridges
(24) and grooves (26) to the web, the heat-set condition of the
dry-creped thermoplastic fibers (8) preserving the ridge (24) and
groove (26) configuration during prolonged presence in the web of
the wet agent (16), c. the wet wiping agent (16) being disposed
through the body and on the surface of the dry-creped, heat-set
sheet-form member and its constituent fibers (8, 9).
24. A package (18) comprising a face-to-face stack (21) of a
plurality of sheet members (22), each sheet member comprising: a. a
segment of a non-woven self-supporting web (11, 120, 150) comprised
of an assemblage of fibers (8, 9) including synthetic thermoplastic
fibers (8) b. the non-woven web (14) being in a permanent,
dry-creped, heat-set volume-enhanced condition, the constituent
thermoplastic fibers (8) of the sheet member having been heat-set
simultaneously during the imparting of ridges (24) and grooves (26)
to the web, the heat-set condition of the dry-creped thermoplastic
fibers (8) capable of preserving the enhanced volume structure of
the assemblage during prolonged presence in the web of the wet
agent (16).
25. A method of producing a wet wipe product (22) comprising: a.
providing a self-supporting non-woven assemblage (11, 150) of
hydroentangled fibers (8, 9) including synthetic thermoplastic
strength-providing fibers (8) and absorbent or adsorbent fibers
(9), b. passing the non-woven assemblage (11, 120, 150) through a
dry-creping machine (149) to impart ridges and grooves to a body
(30) of the assemblage while simultaneously heating the assemblage
to a temperature above the temperature required to heat-set the
thermoplastic fibers (8), and c. thereafter sizing the assemblage
into a wipe member (22), pre-applying a wet wiping agent (16) so
that the wet wiping agent is disposed through the body (30) and on
the surface of the dry-creped sheet-form member and its constituent
fibers (8, 9), and sealing the wipe member in a fluid-tight package
(18).
26. A method of producing a wet wipe product (22) comprising: a.
providing a self-supporting non-woven sorbent assemblage (11, 150)
of fibers (8, 9) including synthetic fibers (8), b. passing the
non-woven assemblage (11, 120, 150) through a dry-creping machine
(149) to impart ridges and grooves to a body (30) of the assemblage
while simultaneously heating the assemblage to a heat set
temperature to heat-set the thermoplastic fibers (8) to thereby
enhance the sorbent volume structure of the assemblage, and c.
thereafter sizing the assemblage into a wipe member (22).
27. The method of claim 20 or 21 in which the dry-creping is
performed under conditions to produce coarse dry-crepe.
28. The method of claim 27 comprising employing a spunlace process
for providing the nonwoven assemblage (11, 150).
29. The method of claim 27 in which the assemblage (11, 120, 150)
is formed by providing a carded web of polyester fibers (8)
introducing a layer of wood pulp (9) to the carded web, and
subjecting the layer of wood pulp and carded web to
hydroentanglement followed by dewatering and drying prior to
dry-creping.
30. The method of claim 27 comprising conducting the dry-creping
step with a bladed drycreper comprising a driven roll (152), a
pressing surface (154, 155) pressing the fiber assemblage (150)
against the driven roll sufficiently to cause the fiber assemblage
to be advanced forward, and opposing the advance of the assemblage
in the direction of the plane of the assemblage with a retarder
blade (156), a tip of which is held adjacent the driven roll, at
least one surface of the drycreper being heated to heat the
thermoplastic fiber constituent to heat-set temperature of the
thermoplastic fibers.
31. The method of claim 30 in which sorbent fibers (9) in the
assemblage comprise wood pulp fibers, the fiber assemblage is
substantially free of thermoplastic binder, and the dry-creping is
conducted in a manner leaving the wood pulp fibers substantially
permanently uncompressed in the direction of the thickness of the
assemblage.
32. The method of claim 30 in which the thermoplastic fibers (8)
include PET (polyester) and said surface of the drycreper (149) is
heated to a temperature above 250.degree. F. sufficient to set the
thermoplastic fibers.
33. The method of claim 31 in which the pressing surface (154, 155)
is so heated.
34. The method of claim 32 in which the driven roll (152) is so
heated.
35. The method of claim 31 in which the driven roll (152) is so
heated.
36. The method of claim 30 in which the dry-creping and
simultaneous heat setting is carried out under conditions in which
the absorbent or adsorbent fibers (9) are substantially
uncompressed in a direction of thickness of the web (11, 120, 150)
during formation of the dry-crepe.
37. The method of claim 30 in which the driven roll (152) of the
drycreper includes a continuous cylinder, the roll being equipped
with an internal heater (H').
38. The method of claim 37, wherein the internal heater (H')
comprises an electric resistance heater.
39. The method of claim 37, wherein the internal heater (H')
comprises heat exchange passages containing a hot fluid.
40. The method of claim 39, wherein the hot fluid is one of hot
water, steam, hot gas, hot air, combustion gas or oil.
41. The method of claim 31 in which the dry-creping and
simultaneous heat-setting is conducted in a manner to shorten the
web (11, 150) at least 4%, increasing a bulk thickness of the sheet
member.
42. The method of claim 41 in which the dry-creping and
simultaneous heat-setting is conducted in a manner to shorten the
web (11, 120, 150) within the range between about 4 to 25%.
43. The method of claim 41 in which the dry-creping and
simultaneous heat-setting is conducted in a manner to shorten the
web (11, 120, 150) within the range between about 4 and 12%.
44. The method of claim 41 in which the dry-creping and
simultaneous heat-setting is conducted in a manner to shorten the
web (11, 120, 150) within the range between about 4 and 8%.
45. The method of claim 30, in which a plurality of said sheet
members (22), in a stack (21) in face-to-face contact, are packaged
wet in a fluid tight container (18).
46. The method of claim 45 including adding to the sheet members
(22) before completing the packaging one of a soap, a detergent, a
solvent, a cleaning, a window washing, a sanitizing, a biociding, a
polishing, an abrading and a neutralizing agent.
47. The method of claim 45 including adding to the sheet members
(22) before completing the packaging one of an insect repellant, a
paint solvent, a paint remover, a finish remover, an oil solvent, a
grease solvent, a cosmetic remover, a makeup remover, a stain
remover, a stain, a paint, a varnish, a wax and a polish.
48. The wet wipe product of claim 1 or 2 or the method of claim 26
wherein the fiber content of said nonwoven assemblage comprises at
least 20% by weight thermoplastic synthetic fibers.
49. The subject of claim 48 in which the web is contacted with a
surface heated between about 250.degree. F. to 425.degree. F. to
heat set the thermoplastic fibers.
50. The subject of claim 49 in which the thermoplastic fibers are
polypropylene and the temperature of the surface is between 250 and
300.degree. F., preferably about 270F.
51. The subject of claim 49 in which the thermoplastic fibers are
polyester and the temperature of the surface is between about 350
and 450.degree. F., preferably about 365F.
52. The non-woven wet wipe product of claim 2, the package of claim
24 or the method of claim 26 in which the nonwoven web comprises a
web formed at least in part by entanglement, bonding or
adhering.
53. The subject of claim 52 in which the web has been formed at
least in part by the process of thermal bonding, chemical bonding,
spunbonding, meltblowing, caustic entangling, hydraulically
aperturing, hydro-entangling, wet laying, or papermaking.
Description
TECHNICAL FIELD
[0001] This invention relates to non-woven wiping sheets and in
particular to so-called "wet wipes", i.e. sheets that are pre-wet
with a desired wiping fluid and sold in a fluid tight container,
and sheets that, though packaged dry, are adapted to be wetted or
significantly moistened by the user.
BACKGROUND
[0002] Wet wipes are typically non-woven materials made of a
combination of synthetic strength fibers and absorbent or adsorbent
fibers, which are usually cellulosic fibers such as wood pulp.
[0003] In other cases the strength fibers are cotton, rayon or
other cellulosic fibers.
[0004] While useful in many instances, present-day wet wipes may
not have the most desirable appearance; they may present
considerable drag to being drawn across a surface being wiped;
their wiping ability is not as good as may be desired. Their fluid
holding, fluid releasing and fluid re-imbibing properties may not
be as good as desired.
[0005] In general improved wet wipes would increase their use and
convenience.
SUMMARY
[0006] One aspect of the invention, in the case of pre-wet
products, pertains to non-woven wet wipe products and methods for
making them, each of the products comprising a sheet member,
pre-wetted with a wet wiping agent, and disposed in a fluid-proof
package, the product including:
[0007] a. a segment of a non-woven self-supporting web comprised of
an assemblage of hydroentangled fibers including synthetic
thermoplastic strength-providing fibers and absorbent or adsorbent
fibers,
[0008] b. the non-woven web being in a permanent, dry-creped,
heat-set condition defining a succession of ridges and grooves in
the overall body of the web, the constituent thermoplastic fibers
of the sheet member having been heat-set simultaneously during the
imparting of the ridges and grooves to the web, the heat-set
condition of the dry-creped thermoplastic fibers preserving the
ridge and groove configuration during prolonged presence in the web
of the wet wiping agent,
[0009] c. the wet wiping agent being disposed through the body and
on the surface of the dry-creped, heat-set sheet-form member and
its constituent fibers.
[0010] In preferred embodiments the sheet is coarsely dry-creped,
and the resultant coarse ridges in the fabric contribute to
enhanced performance.
[0011] "Dry-creping" referred to here means creping a preformed
web, without the web being adhesively adhered to a surface (as in a
Yankee dryer) and does not preclude the addition of limited
moisture during the process, as by adding a modicum of steam to the
web to soften fibers to facilitate the dry-creping action.
[0012] By "coarse" in reference to the ridge and groove formations
imparted to the sheet member by dry, coarse creping while
heat-setting, is meant a ridge and groove pattern that, rather than
being microscopic or virtually invisible, is sensibly prominent, in
general, comprising fewer than about 25 ridges per lineal inch.
[0013] Within this parameter, very important further
characteristics can be obtained with many webs by the coarse
formations. The desirable effects obtained depend upon the type of
desired wipe action.
[0014] In other important cases, the invention pertains to wet
wipes which may be pre-wetted, or sold dry to be wetted by the
user, that are formed of nonwoven starting materials that may
employ a great variety of fibers typically having adsorbent and
wicking characteristics, while at least 20% of the fibers in the
assembly being thermoplastic and capable of being heat set. The
starting web materials can be made via a variety of nonwoven
manufacturing processes including thermal bonding, chemical
bonding, spunbonding, meltblowing, caustic entangling,
hydraulically aperturing, wet laying, papermaking and combinations
of these method. In some advantageous cases, hydroentanglement is
employed to provide fiber entanglement and coherency of the web. In
other cases, other fiber entanglement or bonding or adhering
processes are employed to form a coherent web preform. Such web
preforms, however made, are then processed according to the present
invention, are dry-creped under heating conditions that heat set
the creped thermoplastic fibers to produce a volume enhanced
structure. These materials are processed to provide pre-wet wipes
in fluid tight containers and wipes that are designed for use after
the user wets them, being packaged dry in a package that may or may
not be fluid tight.
[0015] With wet wipes for which a vigorous wiping action is
desired, it is advantageous to employ a gross coarse crepe, i.e.
the heat set ridge frequency is between about 8 and 15 per lineal
inch. The resultant strongly pronounced ridges effectively provide
wipe-stress-concentrating edges that enable high wiping pressure
(pounds per square inch) to be applied to the edges (the entire
wiping force thus being distributed over a relatively low aggregate
length of relatively sharp edges). Further, the grossly heat-set
coarse dry crepe can contribute significant overall thickness to a
single wipe, and, because of the relative randomness of ridges in
one wipe sheet in a stack relative to the next, arising because of
the absence of complete irregularity in the ridge pattern inherent
with creping, the sheets are prevented from nesting, contributing
significantly to the space occupied by a single wipe in a stack of
wipes. The crepe ridges and grooves thus increase the
fluid-carrying capacity of the individual wipes, which is important
where a significant flood of the wet wiping agent is required.
[0016] In important embodiments, the creping with heat set
increases the recoverable internal volume of the nonwoven fabric.
By "recoverable volume" is meant, that, after being squeezed to
deliver liquid, and then released, the liquid carrying volume is
recoverable, i.e. the web swells by itself, or when it imbibes
liquid, its internal volume swells, so that a significant volume of
the liquid is retained. This recoverable volume characteristic of
the heat set, creped product increases the ability of the wipe
material to adsorb liquids. Further, to the degree the adsorption
is increased, it is important to note that the reciprocal ability
to desorb liquids is increased. Thus a treated wipe can adsorb a
liquid, then when squeezed or subjected to wipe pressure, it can
desorb to deliver the liquid to the surface being wiped, subsequent
to which it can resorb the liquid to remove liquid along with
picked-up contaminant from the wiped surface. Both sorbing and
desorbing characteristics of the web are increased by the creped,
heat set thermoplastic network of fibers in assemblies that have
wettable fibers with appropriate wicking capability. In important
embodiments, the aggregate interstitial space between adjacent
fibers, and accordingly the overall internal volume of the wipe, is
increased by the heat set creping. The treatment enables improved
liquid adsorption, desorption and resorption, likened to an
effective pumping action, with respective relaxation, compression,
and relaxation of compressive action of the user upon the surface
being wiped.
[0017] With wet wipes for which a moderate wiping action is
desired, according to the invention it is readily possible to
tailor the conditions of treatment to produce moderately coarse
formations, i.e. between about 15 and 20 heat-set ridges per lineal
inch. Again there is obtained the stack thickness-enhancing effect
of non-alignment of ridges in successive layers of a stack, and
significantly enhanced thickness and fluid-carrying capacity to the
individual wet wipe sheet. The greater density of ridges spreads
the wiping force over a longer aggregate ridge length, producing
lower, but still significant contact pressure at the ridge
edges.
[0018] For cosmetic use, baby care and other uses in which gentle
action is desired, minimally coarse ridges, i.e. between about 20
to 25 ridges per lineal inch, provide the possibility of a
relatively gentle wiping action while still obtaining, to a reduced
degree, the thickening and liquid-capacity enhancing advantages of
the invention.
[0019] There are cases where even a finer distribution of the
heat-set dry crepe formations in the hydroentangled wet wipe may be
employed, as well, e.g. for hypersensitive skin use. In some
examples of hydroentangled and other web structures, the crepe
pattern is selected to be so fine that it is hard to detect
visually without magnification, but the physical changes in
internal volume, stretch at break, thickness and liquid capacity
will be apparent, all provided by the heat set thermoplastic crepe
structure.
[0020] Another feature of the invention, which is important, e.g.,
for the vigorous and moderate action wipes, is the effect obtained
in wiping a smooth surface such as glass or metal plate, or other
continuous surface. This has to do with a vacuum-release effect
achieved by the permanent fluid-resistant ridge and groove
structure, which is particularly noteworthy when employing gross
coarse crepes heat-set in the wet wipe. Despite the sheet member
having a high fluid-carrying capacity, it is found, during use,
that the troughs of the sheet are not completely fluid-filled, i.e.
continuous air channels are preserved between adjacent ridges,
which communicate with ambient. These air channels are partially
retained in the pre-wet sheet even when significant wipe pressure
is exerted. Relatively smooth wet wipe sheets (i.e. sheets not
having features of the present invention) when pressed against a
flat surface being wiped, give up entrapped air at the interface
and then tend to be forced, by ambient air pressure, bodily against
the surface being wiped. According to the present invention it is
realized that this pressure adds to frictional resistance to
lateral movement of the wipe sheet across the work surface,
increasing the effort required, by the worker. The coarse creped,
heat-set ridges and grooves of wet wipes of the present invention,
on the other hand, while achieving improved concentration of wipe
pressure at the working ridges, are formed to effectively reduce
the total wiping effort required, believed to be due to the
presentation of the vacuum-releasing air channels.
[0021] Another feature is that heat set creped wipes that have the
low overall cohesion with the surface being wiped need not be
subject to much distortion by forces applied during wiping. As a
result, the liquid carried is not prematurely discharged, and thus
the user is given good control over the release and recovery of the
solvent or washing liquid.
[0022] Accordingly, in preferred embodiments of the invention, the
wet wipe product has between about 8 to 25 heat-set dry crepe
ridges per lineal inch of the web. For vigorous wiping action, the
wet wipe product has between about 8 and 15 heat-set dry crepe
ridges per lineal inch of the web, for moderate wiping action, the
wet wipe product has between about 15 and 20 heat-set dry crepe
ridges per lineal inch of the web, while for fine or gentle wiping
action, the wet wipe product has between about 20 and 25 heat-set
dry crepe ridges per lineal inch of the web.
[0023] In another aspect, the invention provides a non-woven wet
wipe product including a sheet member, pre-wetted with a wet wiping
agent, and disposed in a fluid-proof package, the product including
a segment of a non-woven self-supporting web made up of an
assemblage of hydroentangled fibers including synthetic
thermoplastic strength-providing fibers and absorbent or adsorbent
fibers. The non-woven web is in a permanent, dry-creped, heat-set
condition defining a succession of ridges and grooves in the
overall body of the web, the constituent thermoplastic fibers of
the sheet member having been heat-set simultaneously during the
imparting of the ridges and grooves to the web. The heat-set
condition of the dry-creped thermoplastic fibers preserve the ridge
and groove configuration during prolonged presence in the web of
the wet agent. The wet wiping agent is disposed through the body
and on the surface of the dry-creped, heat-set sheet-form member
and its constituent fibers.
[0024] These and other described aspects of the invention can
include one or more of the following additional features. The sheet
has been coarsely dry-creped, resulting in a coarse distribution of
ridge formations in the sheet. There are between about 8 and 25
heat-set ridges per lineal inch of the web (between about 3.1 and
9.8 ridges per linear cm). There are between about 8 and 15
heat-set ridges per lineal inch of the web (between about 3.1 and
5.9 ridges per lineal cm). There are between about 15 and 20
heat-set ridges per lineal inch of the web (between about 5.9 and
7.9 ridges per lineal cm). There are between about 20 and 25
heat-set ridges (24) per lineal inch of the web (between about 7.9
and 9.8 ridges per lineal cm). The sheet member is made up of
between about 1/3 and 2/3 by weight absorbent or adsorbent fibers
and between about 1/3 and 2/3 by weight of synthetic thermoplastic,
strength-imparting fibers. The sheet member has at least 20% of its
fibers weight as heat-settable thermo plastic fibers. The sheet
member comprises about equal weight of the absorbent or adsorbent
fibers and the thermoplastic which may be strength providing. The
thermoplastic fibers include PET (polyester). The thermoplastic
fibers include polypropylene. The thermoplastic fibers include
polyethylene. The absorbent or adsorbent fibers are cellulosic. The
cellulosic fibers are natural fibers. The absorbent or adsorbent
fibers include rayon. The wet wipe product includes fibers of PET
and fibers of wood pulp. As in the case of wipes for use with
alcohol, the nonwoven can be made entirely of adsorbent fibers and
not contain any absorbent fibers. The pre-form web from which the
wet wipe product is made is a spunlace web. Other embodiments
include all the types of nonwovens previously mentioned above,
including wet laid products.
[0025] The wet wiping agent is, at least partially, an aqueous
agent. The wet wiping agent includes a soap, a detergent, a
solvent, a cleaning, a window washing, a sanitizing, a biociding, a
polishing, an abrading and/or a neutralizing agent. The wet wiping
agent includes an insect repellant, a paint solvent, a paint
remover, a finish remover, an oil solvent, a grease solvent, a
cosmetic remover, a makeup remover, a stain remover, a stain, a
paint, a varnish, a wax and/or a polish. The wet wiping agent is a
liquid that does not include water such as hydrocarbon solvents,
nonaqueous coatings, and the like or the wipe is made to adsorb and
pick-up such liquids.
[0026] In another aspect, the invention provides a package
containing a face-to-face stack of a plurality of sheet members,
each sheet member being a segment of a non-woven self-supporting
web made up of fiber assemblage, e.g., of hydroentangled fibers,
including synthetic thermoplastic strength-providing fibers and
absorbent or adsorbent fibers. The non-woven web is in a permanent,
dry-creped, heat-set condition defining a succession of ridges and
grooves in the overall body of the web, the constituent
thermoplastic fibers of the sheet member having been heat-set
simultaneously during the imparting of the ridges and grooves to
the web. The heat-set condition of the dry-creped thermoplastic
fibers preserves the ridge and groove configuration during
prolonged presence in the web of the wet agent. The wet wiping
agent is disposed through the body and on the surface of the
dry-creped, heat-set sheet-form member and its constituent
fibers.
[0027] This aspect of the invention can include any one or more of
the features discussed above with reference to the other aspects of
the invention.
[0028] In another aspect, the invention provides a method of
producing a wet wipe product including providing a self-supporting
non-woven assemblage of e.g., hydroentangled fibers including
synthetic thermoplastic fibers which may be strength-providing and
absorbent or adsorbent fibers; passing the non-woven assemblage
through a dry-creping machine to impart ridges and grooves to a
body of the assemblage while simultaneously heating the assemblage
to a temperature above the temperature required to heat-set the
thermoplastic fibers; and, thereafter, sizing the assemblage into a
wipe member, pre-applying a wet wiping agent so that the wet wiping
agent is disposed through the body and on the surface of the
dry-creped sheet-form member and its constituent fibers, and
sealing the wipe member in a fluid-tight package, or packaging the
wipe dry to be wetted by the user.
[0029] This aspect of the invention can include any one or more of
the following additional features. The dry-creping is performed
under conditions to produce coarse dry-crepe. A spunlace process is
employed for providing the nonwoven assemblage. The assemblage is
formed by providing a carded web of polyester fibers, introducing a
layer of wood pulp to the carded web, and subjecting the layer of
wood pulp and the carded web to hydroentanglement followed by
dewatering and drying prior to dry-creping. The method includes
conducting the dry-creping step with a bladed drycreper including a
driven roll and a pressing surface for pressing the fiber
assemblage against the driven roll sufficiently to cause the fiber
assemblage to be advanced forward, and opposing the advance of the
assemblage in the direction of the plane of the assemblage with a
retarder blade, a tip of which is held adjacent the driven roll, at
least one surface of the drycreper being heated to heat the
thermoplastic fiber constituent to heat-set temperature of the
thermoplastic fibers. The absorbent or adsorbent fibers include
wood pulp fibers, the fiber assemblage is substantially free of
thermoplastic binder, and the dry-creping is conducted in a manner
leaving the wood pulp fibers substantially permanently uncompressed
in the direction of the thickness of the assemblage.
[0030] In many cases of webs that contain wood pulp, melt blown,
and other very small fibers, as a result of heat and pressure
caused by their nonwoven manufacturing process, the fibers become
closely packed together. Such action can induce detrimental
hydrogen bonding and inelastic densification of the fiber mass. The
creping with heat set described here serves to increase the space
between such small fibers, thus increasing internal volume of the
web, and the adsorbent capacity and rate of wetting of wipes
produced from the web.
[0031] The thermoplastic fibers include PET (polyester) and the
surface of the drycreper is heated to a temperature between about
250 and 350 F (139 C and 194 C). In other embodiments of process
conditions, roll temperatures may be higher (e.g. to accomplish
greater speed, and to drive off moisture to enable the fibers to
reach heat set temperature more quickly) or lower (e.g. if the heat
of friction provides additional heating of fibers.) The pressing
surface and/or the driven roll are heated. The dry-creping and
simultaneous heat setting is carried out under conditions in which
the absorbent or adsorbent fibers are substantially uncompressed in
a direction of thickness of the web during formation of the
dry-crepe. The driven roll of the drycreper includes a continuous
cylinder, the roll being equipped with an internal heater (H'). The
internal heater (H') employs an electric resistance heater. The
internal heater (H') includes heat exchange passages through which
a hot fluid is passed. The hot fluid is hot water, steam, hot gas,
hot air or combustion gas, or oil. The dry-creping and simultaneous
heat-setting is conducted in a manner to shorten the web at least
4%, increasing bulk thickness of the sheet member. The dry-creping
and simultaneous heat-setting is conducted in a manner to shorten
the web within the range between about 4 to 25%. The dry-creping
and simultaneous heat-setting is carried out to provide shortening
between about 4 and 12%. The dry-creping and simultaneous
heat-setting is carried out to provide shortening between about 4
and 8%. A plurality of the sheet members, in a stack and in
face-to-face contact, are packaged wet in a fluid tight container.
The method includes adding to the sheet members before completing
the packaging a soap, a detergent, a solvent, a cleaning, a window
washing, a sanitizing, a biociding, a polishing, an abrading and/or
a neutralizing agent. The method includes adding to the sheet
members before completing the packaging an insect repellant, a
paint solvent, a paint remover, a finish remover, an oil solvent, a
grease solvent, a cosmetic remover, a makeup remover, a stain
remover, a stain, a paint, a varnish, a wax and/or a polish. In
other cases the wipes are dry packed and wetted by the user.
[0032] In the spirit of this invention it is understood that
heating the nonwoven web for accomplishing the heat set of the
crepe can be accomplished in a variety of ways. Rollers may be used
to conduct heat to the web prior to creping, the rollers heated
e.g. by electrical resistance or radiant heat or hot oil. The
nonwoven web can also be heated using radiant energy, hot air or a
variety of other well known methods to set previously imparted
crepe.
[0033] The details of one embodiments of the invention are set
forth in the accompanying drawings and the description below. Other
features, objects, and advantages of the invention will be apparent
from the description and drawings, and from the claims.
DESCRIPTION OF DRAWINGS
[0034] FIG. 1 is a flow diagram of the new process of the
invention.
[0035] FIG. 2 is a magnified view of a pre-moistened wipe produced
by the process of FIG. 1.
[0036] FIGS. 3 and 4 are successively magnified diagrammatic views
of a portion of the product of FIG. 2.
[0037] FIGS. 5, 5A, 5B and 5C are photo views of the faces of
selected preferred embodiments of the product of the invention
prior to application of the moistening agent.
[0038] FIG. 6 is a diagrammatic view of one preferred method of
forming a pre-form product of hydroentangled fibers while FIGS.
6A-6E are diagrammatic view of complete machines for forming
hydroentangled pre-form products.
[0039] FIG. 7 diagrammatically illustrates a pre-formed
hydroentangled product and the foraminous surface on which it is
formed.
[0040] FIG. 8 is a diagrammatic view of a preferred form of the
dry-creping step of the process illustrating the application of
heat to the hydroentangled product during the dry-creping
process.
[0041] FIG. 9 is a perspective illustration of a preferred
drycreper machine, while
[0042] FIG. 10 illustrates, in cross-section, machine components
that apply heat during the processing of the fabric.
[0043] FIG. 11 illustrates shortening of the web as it passes
through the drycreper,
[0044] FIG. 12 is a cross-sectional view of a microcreping cavity
of a bladed microcreper while
[0045] FIG. 13 is a diagram of the conformation of the dry-creping
cavity through which the material is passed.
[0046] FIG. 14 shows a thickness-measuring device measuring a stack
of untreated sheets while
[0047] FIG. 15 shows the same device measuring a stack of the same
number of sheets treated according to the invention.
DETAILED DESCRIPTION
[0048] Referring to FIG. 1 a composite web is formed to provide a
pre-form web 11 for manufacture of the product. The constituents of
pre-form are thermoplastic strength-providing fibers 8, presently
preferred, the fibers containing PET, and fibers of sorbent
material 9, presently preferred, hygroscopic wood pulp. The
percentage by weight of absorbent or adsorbent fibers 8 of preform
11 is between about 1/3 and 2/3 while the percentage by weight of
thermoplastic fibers is about within this same range. In some
instances the percentage by weight of absorbent or adsorbent fibers
8 is about equal to that thermoplastic fibers 9. The fibers are
introduced to a machine 10 of suitable construction for providing a
pre-formed web 11, i.e., an assemblage of fibers, having structural
elements throughout the composite, with which are interspersed fine
sorbent fibers.
[0049] A minimum of about 20% heat settable thermoplastic fibers is
required, for enabling formation of the permanent creped structure
that restores the internal, adsorbent volume of the wipe when
pressure on the wipe is released. Other constituents of the web are
selectable based on the particular task and the nature of the
liquids expected to be sorbed or desorbed by the wet wipe.
[0050] The pre-form sheet 11 is introduced to a drycreper machine
12 which is characterized by its application of heat to the
pre-form just before or during the dry-creping process. The applied
heat is of a level sufficient, under creping conditions, to
heat-set the thermoplastic strength-providing fibers to establish
permanence of the crepe configuration under prolonged wet
conditions. Following the dry-creping apparatus 12, the dry-creped
pre-form 14 is introduced to an apparatus 15 that performs a sizing
process and introduces a wiping fluid 16 to the substrate as by
spraying, immersion or flooding. Either before of after application
of wiping fluid 16, the sheet is cut to size and introduced to a
container 18 which is sealed by a top 20, the container containing
a multiplicity, e.g., a stack 21, of individual layers 22 each
containing the wiping fluid 16. These resultant wet wipes 22 are
ready for use by the consumer in a one-step process to perform the
desired action, for instance a cleaning action, a polishing action,
a dusting action or the application of a fluid to a surface.
[0051] Referring to FIG. 2, an individual layer 22 from container
18 has a selected creped configuration such as, for instance, the
crepe undulations as shown. The ridges 24 and grooves 26 in the
pattern are not precisely identical, one to the next, due to the
slightly random or statistical nature of dry-creping, which is
based on columnar collapse of successive segments of the web as the
driving forces are opposed by retarding forces. Due to slight
variations in the thickness, fiber orientation, or fiber
concentration in adjacent increments of the web, the crepe repeat
length, P, varies slightly in adjacent ridge and groove formations.
Because of the randomness of the ridge and groove location on each
sheet, adjacent layers 22 within package 18 are highly unlikely to
"nest" together, i.e., some amount of separation exists between
adjacent wipes in the container. This phenomenon reduces the
likelihood that adjacent sheets will cling to one another and helps
to ensure that a single wipe can be removed without "pull along,"
e.g., b y friction or adhesion, of a directly subjacent wipe.
[0052] Depicted in FIG. 2 are pockets 28 of fluid 16 contained in
crevices formed by the dry-crepe ridges 24 and grooves 26, and
within the body 30 of the dry-creped fabric. The further magnified
view of FIG. 3 illustrates better that quantities of fluid 16 are
trapped within the interstices of the substance of the layer 22 and
in the conformations provided by the dry-crepe that has been
heat-set. Illustrated also in FIGS. 3 and 4 are continuous regions
34 of air in the channels or troughs of the pre-wet sheet. These
channels communicate with ambient air.
[0053] FIG. 4 depicts, diagrammatically, the thermoplastic fibers 8
in their heat-set condition, forming the web as a whole into the
permanent crepes. FIG. 4 also depicts the hydroentangled absorbent
fiber 9 constituent of the substrate. Again, the aggregations of
moisture 16 are depicted, it being also understood that a large
percentage of the moisture can be imbibed in the body 30 of fibers
of the absorbent pulp or other hygroscopic component of the
web.
[0054] Referring to FIG. 5, the somewhat random distribution of
ridges from one region, e.g., region 36, of a sheet 22 to another,
e.g., region 38, is clearly seen. Referring now also to FIGS.
5A-5C, sheets 22, 22', 22" and 22'" illustrate the varying degrees
of coarse dry-crepe that are achievable, such varying degrees being
suitable for customizing a wet wipe to different particular
applications. As an example, an infant care wipe or a cosmetic wipe
may have the finer heat-set crepes of sheet 22'" (FIG. 5C), with
ridges at density of the order of 20 to 25 per lineal inch, while a
wipe suitable for window cleaning, dusting, or wiping of machinery
may have the grossly coarse configuration of sheet 22 (FIG. 5),
with ridge density between about 8 and 15 ridges per inch. Sheets
22' and 22" (FIGS. 5A and 5B, respectively) illustrate intermediate
products. The crepe frequency is easily selectable by the setting
of the drycreper machine 14 (FIG. 1) to tailor the conformation of
the fabric to the type of wiping agent that is to be added for the
pre-moistened wipe product desired.
[0055] In the presently preferred embodiment, the step 10 (FIG. 1)
of pre-forming the web is performed employing the spunlace process
that is well known. That process involves hydroentanglement of
fibers, such as generally described in the early patents of DuPont,
for instance U.S. Pat. No. 3,485,706, and in early patents of
Chicopee Mills, for instance U.S. Pat. Nos. 3,679,535 and 3,679,536
and the many later patents in the field which make reference to
these early patents. For instance, the reader is referred to U.S.
Pat. Nos. 5,240,764; 5,254,399; 5,227,224 and 5,284,703. Another
example is UK Patent Publication 2 114 173A.
[0056] The general, presently preferred process is illustrated in
FIGS. 6A and 6B. The drawings indicate that the basic elements of
the spunlace process involve a web-former 40, a forming surface 42,
in this case an open weave plastic or wire belt, high-pressure
water jets 44, a dryer 46 and a windup station 48 for the
hydroentangled pre-form product. In practice, web former 40,
delivers, e.g., a dry formed web or a wet formed web of fibers as a
loose pre-formed web or batt 41 onto the forming surface 42. While
in contact with the forming surface, the web or batt is subjected
to the high-pressure water jets. In some embodiments, such as the
one illustrated in FIG. 6B, vacuum boxes 47 are provided adjacent
the forming surface on a side opposite water jets 44 to enhance the
entangling energy applied to the web formation 41. In any event,
the energy in the water stream displaces the fibers of the web or
batt from the solid filaments 43 making up the forming surface 42
and works the fibers into the interstices 45 between the forming
surface filaments, see FIG. 7. In the process, the force of the
water also twists and entangles the fibers so that a strong
integrated fabric 50 is obtained which may have the appearance of
the reverse image of the forming belt or surface. Referring further
to FIG. 7, the non-woven web 50 has been formed and water jet
entangled on forming surface 42, e.g., an open weave belt.
[0057] In the early process known as the Evans process, as
described in U.S. Pat. No. 3,485,706, textile-like non-woven
fabrics were produced by traversing fibrous materials with
high-energy liquid streams while the materials were supported on an
apertured member such as a perforated plate or a woven wire screen.
The action served to consolidate the material in a repeating
pattern of entangled fiber regions and interconnecting fibers. With
this process various types of fibers can be employed, for instance
staple fiber and continuous filament. In the case of the present
invention, the fibers are formed as a composite, including
synthetic thermoplastic fibers and sorbent fibers. In general, in
the early days, the preferred range of openness of the forming
surface was considered to be between about 35 to 65 percent and the
water pressure used was preferably in the range of 200 psi to 1200
psi (1.4 to 8.3 mPa). The orifice diameters for the water jets were
recognized to lie in the range of between 0.003 inch and 0.030 inch
(0.08 to 0.8 mm.) in diameter.
[0058] Another process known from the Honeycomb Systems Company is
illustrated in FIG. 6C. This shows a web former 40, a drum
entangling unit 44a, a water extraction roll 45 and a through air
dryer 46. A honeycomb roll adds a support medium providing for a
compact machine design with the option of entangling on both sides
of the web by employing two drum entanglers. A further advantage of
the equipment lay in the fact that the high open area and rigid
structure of the honeycomb shell provided support to the substrate
while allowing the diffused water from the high pressure jets to
pass through the shell to vacuum slots.
[0059] In the machine described in FIG. 6D known as the "Perfect
Process", the web is first pre-entangled using waterjets J and then
a curtain of water W ranging from 3 to 8 mils in thickness is
passed through a perforated cylinder C and through a fiber web F
which is positioned on a backing belt. As the water curtain passes
through the perforated cylinder, precise jets of water form and
shape a pattern corresponding to the screen pattern. This patterned
water screen rearranges the fiber webs to the screen pattern.
[0060] The processes illustrated in FIGS. 6A, 6B, 6C and 6D are
further described in a technical paper, entitled "Spunlace
Processes Worldwide," by Peter N. Britton, Ph.D., to which article
the reader is referred.
[0061] In the embodiment of FIG. 6E a forming screen 100 receives a
carded web 102 of PET fibers and an equal quantity of wood pulp
104, which is deposited upon carded web 102. This composite 106 is
passed to a first hydrobond station 108 in which high-pressure
water jets (not shown) cause entanglement of the wood pulp fibers
with themselves and with the fibers of the thermoplastic strength
web. The resulting web 110 is then in effect turned over and
subjected to a second hydrobonding action at a second hydrobonding
station 112, which further entangles the fibers making up the
composite. From there the web 114 is passed to a squeeze nip 116
for removing excess water and then the composite is introduced to a
heated dryer 118 for removing the moisture and producing the dried
hydroentangled web 120 which is wound in a reel 122 for further
processing.
[0062] The presently preferred machine for conducting dry-creping
of such composite webs is described in U.S. Pat. No. 3,260,778, to
which the reader is referred, some of the drawings of which are
substantially reproduced in the present application as FIGS. 8-13.
The composite hydroentangled web 150 is introduced to the drive
roll 152 and under a stationary presser member 154, referred to in
the patent as a "shoe," which has an underlying sheet member 155
that presses web 150 against the advancing drive roll 152 to cause
the web to be driven forward towards a retarder element 156. The
dimensions of the cavity formed by roll 152, sheet member 155 and
retarder 156, see FIG. 13, further described below, are adjusted to
a relatively wide final condition to enable the web to be coarsely
folded upon itself by repeated columnar collapse of the sheet, to
form the preferred coarse ridges and grooves that have been
described. While the web receives no substantial squeezing pressure
in the direction of its thickness, the web is dimensionally
constrained, thickness-wise, to establish the coarseness of the
dry-crepe.
[0063] Referring particularly to the diagram of FIG. 13, W
indicates the nip thickness of the material, Y indicates the
original thickness of the material, Z indicates the maximum
separation of the divergent surfaces, R indicates the minimum
separation of the surfaces of the retarding passage, referred to as
the retarding restriction, .theta. indicates the obtuse angle
between material on the moving surface as it approaches the
retarding surface and the resultant of retarding forces imposed by
the retarding passage at its retarding restriction R and .PHI.
indicates the substantial acute angle included between retarding
surface and the direction of movement of the traveling surface. The
treatment cavity comprising zones B+C begins where the diverging
walls are spaced apart a distance Y corresponding substantially to
the original thickness of the material. The separation of the
diverging surfaces increases progressively to its maximum dimension
Z and then the cavity converges to the retarding restriction R. In
operation the pile of micro condensed material extends through the
obtuse angle .theta. back into the divergent passage from retarding
restriction R, through the maximum dimension Z, thus longitudinally
transmitting resistance forces from the retarding passage which
oppose the fresh material forced forward into the divergent
passage. Change in the retarder angle .PHI. changes the value of
obtuse pile angle .theta. for any given relation of the other
elements. With this preferred embodiment, in order to obtain the
needed high resistance forces in the needed short length treatment
cavity, and to obtain smooth movement of the material from the
traveling surface to the retarder surface without cutting, the
angle .PHI. must be substantial, and not highly acute. But if angle
.PHI. is too great, then the pile of condensed material will buckle
into the open "V" causing jamming of the machine or shearing of the
material. Thus, angle .PHI. must be a substantial acute angle as
noted above. For any given set of conditions there is generally
found an optimum angle setting which cooperates with the force
action of the other elements to obtain optimum micro condensing. It
has been found that with changes in the total dimension B+C to
treat differing materials which involves substantial movement of
the retarding surface relative to zone A, if the angle .PHI.
remains constant, smooth flow of the material and proper
transmittal of resistance by the pile results.
[0064] Referring to FIG. 12, substantially simultaneously with
being dry-creped, heat is applied to web 150, for instance by
heaters H associated with the presser member 154 and/or by heaters
H' disposed in the driven roll 152. The heating mode may be any of
the numerous known kinds, e.g., electric resistance, steam, hot
water, hot gas or hot air. Radiant or flame pre-heating may also be
employed. The heat thus imparted to the fabric cooperates with
mechanical heat generated in the physical dry-creping action and
the pressure applied to the sheet material in the directions of the
plane of the material when the (preferably coarse) crepes are
pushed against each other to effectively, permanently deform the
thermoplastic constituents of the web to impart permanent ridges
and grooves to the material that resist prolonged presence of
wiping fluid.
[0065] After being so treated, the web is passed to station 16
(FIG. 1) where fabrication of the wet wipes is completed.
[0066] While the bladed drycreper shown is presently preferred, see
U.S. Pat. No. 3,260,778, other dry-creping machines may be employed
in appropriate instances, for instance those machines described in
U.S. Pat. Nos. 3,810,280; 3,869,768; 3,975,806; 4,142,278;
4,894,196; 4,859,169 and 3,236,718, may also be employed. The
reader is referred to each of these publications.
[0067] The adjustment of the retarder blade 156 back from the
presser member 154 and its associated sheet member 155 is effective
to open the dry-crepe cavity (FIG. 9) to increase the size and
decrease the frequency of the crepes.
[0068] Other alternative methods and apparatus suitable for
carrying out the dry-creping process of the present invention are
disclosed in Walton U.S. Pat. No. 2,915,109 and Packard U.S. Pat.
No. 4,090,385, to which the reader is also referred. Briefly, these
references show longitudinally compacting a web by feeding it over
a roll that has alternating, circumferential ribs and grooves along
its length. A flat shoe presses the web against the roll to enable
the ribs of the roll to drive the web forward. Then a cylindrical
comb (rotating with a peripheral speed lower than the roll) or a
fixed comb (whose teeth mate with the grooves of the main roll)
lifts the web from the main roll and at the same time compacts it
longitudinally. In the latter case, a wide, flexible metal sheet
extension from the shoe engages the face of the web opposite the
web face that engages the retarder comb, to form with the retarder
comb a confirming passage for the creped material. These methods
and apparatus are modified to provide the necessary heat to
heat-set the thus dry-creped material.
[0069] Referring particularly to FIGS. 12 and 13, the
hydroentangled web 150 is compacted in the dry-creping process,
zones B+C, so that an uncompacted region, zone A, is shortened,
zone D. In some embodiments the percentage of compaction is between
about 4% and 25%, i.e., the material defining the length of zone D
is between about 75% and 96% the length of zone A. In other
embodiments the percentage of compaction is between about 4% and
12%. In yet other embodiments the percentage of compaction is
between about 4% and 8%. In yet other embodiments the residual
compaction is negligible but the changes in thickness and internal
volume, adsorbent capacity and the readsorption capacity are
improved nonetheless.
[0070] Referring to FIGS. 14 and 15, dramatic results achieved by
the invention are suggested by measuring a stack of wipe members
with and without the heat-set dry-crepe treatment described (prior
to application of the wet wiping agent).
[0071] Whereas the stack in FIG. 14 of eight untreated wipes
measures 0.074 inch thickness, the stack eight of wipes with gross
coarse dry-crepe in FIG. 15 measures 0.234 inch thickness (ridges
are not aligned in adjacent sheets due to the slight randomness of
the dry creping process). It is found that, with application of the
wet wiping agent to, for instance, sheets of the preferred
embodiment, the ridges in the sheet members of FIG. 15 are
substantially preserved despite the tendencies of the pulp fibers
to expand and straighten upon imbibing wiping liquid.
[0072] Each and every one of the above referenced publications is
hereby fully incorporated by reference, including: U.S. Pat. Nos.
2,915,109; 3,236,718; 3,260,778; 3,485,706; 3,679,535; 3,679,536;
3,810,280; 3,869,768; 3,975,806; 4,090,385; 4,142,278; 4,894,196;
4,859,169; 5,240,764; 5,254,399; 5,227,224 and 5,284,703, GB Patent
No. 2 114 173A and the technical paper entitled, "Spunlace
Processes Worldwide," by Peter N. Britton, Ph.D., and the
references cited in "Principles of Nonwovens" chapter 4 pages
539-641 edited by John E. Reidel, copyright 1993 by INDA, the
association of the nonwovens industry, as well as the entirety of
this book.
[0073] The following examples are provided and tested under the
following conditions with the advantageous results noted.
[0074] Three different commercial materials were selected:
[0075] (1) A material known as JWS Fibrella No. 4300, from JWS in
Spain, a 70 gram per square meter nonwoven material, the fiber
content of which is 50% polyester fiber and 50% wood pulp, the
nonwoven produced by the technique of hydroentanglement;
[0076] (2) A material known as an Orlandi nonwoven, produced by
Orlandi, SA, of Varesi, Italy, characterized by a weight of 50 gram
per square meter, the fiber content of which is 50% polypropylene
fibers and 50% wood pulp, the nonwoven produced by the technique of
hydroentanglement;
[0077] (3) A material known as Ahlstrom No. 962, a 60 gram per
square meter nonwoven having a fiber content of 50% polyester fiber
and 50% wood pulp, to which an acrylic latex binder of estimated
20% by weight has been added, the nonwoven material produced by a
wet lay process.
[0078] Running lengths of each of these materials were subjected to
microcreping using a commercial bladed microcreper, available from
Micrex Corporation, Walpole, Mass., having a mechanical set up
substantially as shown in FIG. 12. Active heating was provided only
with an oil heated drive roll. Roll surface temperature was 365F
for the two materials containing polyester thermoplastic fibers and
270 F for the material containing the polypropylene fibers. The
dimension Z (FIG. 12) was approximately 0.010 inch in each case.
Each of the materials was treated employing a line speed of
approximately 200 meter per minute, and the take-up speed of the
machine was adjusted relative to the feed to produce compaction
(shortening of the web length) at about the 15% level.
[0079] Absorbency testing was conducted according to the INDA test
method 10.1 (95) paragraph 8 (INDA is a trade association of the
nonwovens industry, located in Cary, N.C.). Thickness was measured
employing thickness gauge No. 202, available from the Ames Co.,
Beverly, Mass., using a 17/8 inch diameter foot.
[0080] The results are given in the following table with respect to
an individual wipe sheet of planar dimensions 4 inch width and 7
inch length. The absorbency tests were performed on stacks of
sheets weighing 5 grams per stack (dry) according to the test
methodology. Both dry and wet weights were calculated by dividing
the stack weight by the number of sheets in the stack.
[0081] As the table indicates, the dry density of the wipe sheets
per unit area increased due to compaction by the microcreper in
accordance with the approximate 15% compaction (shortening of the
length) produced by the treatment.
[0082] The increase in dry thickness of the sheets, measured before
the samples were saturated with water, however, ranged from 46% for
the Orlandi fabric, 79% for the JWS Fibrella fabric to 250% for the
Ahlstrom fabric.
[0083] The increase in wet weight of the non-creped and the
microcreped wipes ranged from 22% for the Ahlstrom fabric, 32% for
the Orlandi fabric and 41% for the JWS Fibrellas fabric, each
indicating a significant increase in its liquid capacity.
1 JWS Fibrella #4300, 70 gsm, 50% polyester/50 pulp
(hydroentangled) Creped-15% Property Non-Creped Compaction Change %
Weight- Dry (gms) 1.344 1.564 +16% Thickness Dry (in) 0.0123 0.0220
+79% Weight- Wet (gms) 6.08 8.60 +41% Thickness Wet (in) 0.015
0.025 +66%
[0084]
2 Orlandi 50 gsm 50% polypropylene/50 wood pulp (hydroentangled)
Creped 15% Property Non-Creped Compaction Change % Weight- Dry
(gms) 0.95 1.11 +17% Thickness Dry (in) 0.0150 0.0220 +46% Weight-
Wet (gms) 4.13 5.477 +32% Thickness Wet (in) 0.013 0.018 +38%
[0085]
3 Ahlstrom #962 60 gsm - 50% polyester/50% wood pulp (wet lay
process + acrylic latex binder) Creped 15% Property Non-Creped
Compaction Change % Weight- Dry (gms) 1.0 1.16 +16% Thickness Dry
(in) 0.006. 0.021 +250% Weight- Wet (gms) 3.68 4.52 +22% Thickness
Wet (in) 0.0064 0.0146 +128%
[0086] Within the spirit and scope of the above teachings, numerous
variations in the parameters, combinations and apparatus described
are to be employed depending upon the specific products desired,
and are within the following claims.
* * * * *