U.S. patent application number 14/175190 was filed with the patent office on 2015-08-13 for cleaning sheet and laminates therefor.
This patent application is currently assigned to The Procter & Gamble Company. The applicant listed for this patent is The Procter & Gamble Company. Invention is credited to Stephanie Michelle DOHERTY-STAPP, Juan Carlos FLORES-ESCRIBANO, David John HOYING, David John PUNG.
Application Number | 20150223662 14/175190 |
Document ID | / |
Family ID | 52544565 |
Filed Date | 2015-08-13 |
United States Patent
Application |
20150223662 |
Kind Code |
A1 |
DOHERTY-STAPP; Stephanie Michelle ;
et al. |
August 13, 2015 |
CLEANING SHEET AND LAMINATES THEREFOR
Abstract
A multi-ply cleaning sheet. The cleaning sheet has a preferred
basis weight/cumulative volume combination. This combination
decouples wet cleaning performance from the cost of the sheet
associated with the basis weight of the constituent plies. The
cleaning sheet may be pre-wetted.
Inventors: |
DOHERTY-STAPP; Stephanie
Michelle; (Batavia, OH) ; HOYING; David John;
(Cincinnati, OH) ; FLORES-ESCRIBANO; Juan Carlos;
(West Chester, OH) ; PUNG; David John; (Loveland,
OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Procter & Gamble Company |
Cincinnati |
OH |
US |
|
|
Assignee: |
The Procter & Gamble
Company
Cincinnati
OH
|
Family ID: |
52544565 |
Appl. No.: |
14/175190 |
Filed: |
February 7, 2014 |
Current U.S.
Class: |
15/104.93 ;
15/209.1 |
Current CPC
Class: |
B32B 2262/0253 20130101;
A47L 13/17 20130101; B32B 2432/00 20130101; A47L 13/16 20130101;
B32B 2262/062 20130101; B32B 2260/021 20130101; B32B 5/26 20130101;
B32B 2260/046 20130101; B32B 2270/00 20130101; B32B 5/022
20130101 |
International
Class: |
A47L 13/17 20060101
A47L013/17; A47L 13/16 20060101 A47L013/16 |
Claims
1. A cleaning sheet suitable for being pre-wetted, said cleaning
sheet comprising a first ply and a second ply joined together in a
face-to-face relationship to form a laminate, said first ply
comprising a floor contacting layer having a basis weight of about
35 gsm to about 50 gsm, a cumulative volume at 204 mm H.sub.2O of
about 2 to about 2.7 cubic millimeters per mg of nonwoven material
and said second ply comprising a core layer for holding and
releasing a cleaning liquid, said second ply comprising a synthetic
nonwoven and/or cellulosic material.
2. The cleaning sheet of claim 1, wherein said second ply has a
first face and a second face opposed thereto, and wherein said
floor contacting layer is disposed on said first face of said
second ply, and wherein said sheet further comprises a third ply
backing layer disposed on said second face of said second ply to
form a three ply laminate.
3. The cleaning sheet of claim 2, wherein said floor contacting
layer comprises a spunbond nonwoven.
4. The cleaning sheet of claim 3, wherein said floor contacting
layer comprises a hydroentangled spunbond nonwoven.
5. The cleaning sheet of claim 4 wherein said basis weight of said
floor contacting layer is about 38 gsm to about 45 gsm.
6. The cleaning sheet of claim 4 wherein cumulative volume of said
floor contacting layer at 204 mm H.sub.2O is about 2.3 to about 2.5
cubic millimeters per mg of nonwoven material.
7. The cleaning sheet of claim 5 wherein cumulative volume of said
floor contacting layer at 204 mm H.sub.2O is about 2.3 to about 2.5
cubic millimeters per mg of nonwoven material.
8. The cleaning sheet of claim 7 wherein said second ply has a
basis weight of about 110 gsm to about 160 gsm.
9. The cleaning sheet of claim 8 wherein said floor contacting
layer and said backing layer comprise substantially identical
nonwoven materials.
10. A cleaning sheet according to claim 9 which is pre-wetted.
11. A pre-wetted cleaning sheet comprising: a first ply having a
basis weight of about 35 gsm to about 50 gsm, a cumulative volume
at 204 mm H.sub.2O of about 2 to about 2.7 cubic millimeters per mg
of nonwoven material; a second ply for holding and releasing a
cleaning liquid, said second ply comprising a synthetic nonwoven
and/or cellulosic material, said first ply and said second ply
being joined together to form a laminate; and a cleaning solution
impregnated in said laminate, said sheet having 6 to 8 grams of
cleaning solution per gram of laminate.
12. The cleaning sheet of claim 11 further comprising a third ply
joined to said second ply, whereby said second ply is disposed
between said first ply and third ply, said third ply comprising a
synthetic nonwoven.
13. The cleaning sheet of claim 12 wherein said second ply
comprises at least 50 weight percent cellulose.
14. The cleaning sheet of claim 13 wherein cumulative volume of
said first ply at 204 mm H.sub.2O is about 2.3 to about 2.5 cubic
millimeters per mg of nonwoven material.
15. The cleaning sheet of claim 14 wherein said basis weight of
said first ply is about 38 gsm to about 45 gsm.
16. A pre-wetted cleaning sheet comprising: a first ply having a
basis weight of about 35 gsm to about 45 gsm, a cumulative volume
at 204 mm H.sub.2O of about 2.3 to about 2.7 cubic millimeters per
mg of nonwoven material; a second ply for holding and releasing a
cleaning liquid, said second ply comprising a synthetic nonwoven
and/or cellulosic material, said first ply and said second ply
being joined together to form a laminate; a third ply joined to
said second ply, whereby said second ply is disposed between said
first ply and third ply, said third ply comprising a synthetic
nonwoven; and a cleaning solution impregnated in said laminate.
17. The cleaning sheet of claim 16 wherein said first ply and said
third ply comprise substantially identical nonwoven materials.
18. The cleaning sheet of claim 16 wherein said first ply has a
cumulative volume at 204 mm H.sub.2O of about 2.5 to about 2.7
cubic millimeters per mg of nonwoven material.
19. The cleaning sheet of claim 18 wherein said second ply has a
basis weight of about 110 gsm to about 160 gsm, and said sheet
comprises not more than 10 grams of cleaning solution per gram of
laminate.
20. The cleaning sheet of claim 19 wherein said first ply comprises
a hydroentangled spunbond nonwoven.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to cleaning sheets, and more
particularly to substrates for cleaning sheets which may be
pre-wetted prior to use.
BACKGROUND OF THE INVENTION
[0002] Hard surface cleaning sheets are well known in the art. Such
sheets may be used on the floor, countertop, tables, etc. The
discussion below is directed to floor sheets, but the invention is
not so limited.
[0003] Such sheets may be used dry, to gather dust, crumbs, dirt,
hair, etc. Such sheets may also be used with liquids, to help
solubilize some debris on the floor. The liquid may be separately
applied, as occurs with a separate spray system. Such a spray
system may use an on-board reservoir. The reservoir may be refilled
or replaced when depleted. An example is found in the Swiffer R
WetJet R implement, sold by the instant assignee. Alternatively or
additionally, the sheet may be pre-wetted as presented to the
consumer. Such sheets may be lightly moistened, completely
saturated or have any moisture level therebetween. A commercially
successful pre-wetted sheet has been made under commonly assigned
U.S. Pat. No. 6,716,805 and sold by the instant assignee as
Swiffer.RTM. Sweeper Wet Cloth refills.
[0004] The pre-wetted floor sheets may provide convenience to the
consumer. Separate supplies for wetting the floor, or other
surface, are not necessary. The sheet may be pre-wetted with a
liquid particularly suited for the desired task.
[0005] Such floor sheets may comprise a single ply or a laminate of
two or more plies. The laminated arrangement increases production
costs, but provides the benefit that different layers can be
customized for different uses. For example, a floor contacting
layer may be suited to dirt removal. A core layer may be suited for
holding and releasing the liquid. An optional backing layer may be
suited for removably joining the floor sheet to an optional
cleaning implement.
[0006] Maintaining a relatively low cost for the cleaning sheets
may be desirable. One way manufacturers have tried to economize, is
to use relatively lower basis weight materials and/or to use
relatively lower density weight materials. An example of low
density substrates may be found in US 20070202766/7947613.
[0007] But conserving materials to reduce costs may have tradeoffs.
For example, if the cleaning sheet is used as a floor sheet, the
floor sheet having reduced basis weight may not clean enough area
to complete the task in a single room. The user is inconvenienced
by having to change to a new floor sheet during the cleaning task.
The area a single sheet can clean under controlled conditions is
herein referred to as `mileage.`
[0008] Increasing the liquid loading level may not overcome this
problem. The greater basis weight may not be sufficient to hold the
increased amount of liquid. Furthermore, increasing the amount of
liquid offsets the cost savings sought by conserving materials in
the laminate.
[0009] Accordingly, an approach is desired which reduces costs,
preferentially reduces materials sent to landfill yet still
provides adequate cleaning mileage for the user. But to do so one
must decouple the related properties of basis weight and cleaning
mileage.
SUMMARY OF THE INVENTION
[0010] The invention comprises a cleaning sheet, suitable for being
pre-wetted before being presented to a user. The cleaning sheet
comprises a first ply and a second ply joined together in a
face-to-face relationship to form a laminate. The first ply is a
floor layer having a basis weight of from about 35 gsm to about 50
gsm, and a cumulative volume at 204 mm H.sub.2O of about 2 to about
2.7 cubic millimeters per mg of nonwoven material. The second ply
is a core layer for holding and releasing a cleaning liquid and
comprises a synthetic and/or cellulosic material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A is a top plan view, shown partially in cutaway, of
an exemplary floor sheet according to the present invention.
[0012] FIG. 1B is a fragmentary, exploded schematic vertical
sectional view taken along lines 1B-1B of FIG. 1A.
[0013] FIGS. 2A-4B show various attributes of single ply nonwoven
materials, usable as a floor layer in cleaning sheet according to
the present invention.
[0014] FIGS. 2A-2B are representative pore volume distributions for
commercially available nonwovens.
[0015] FIG. 3A graphically shows performances of various basis
weights of representative spunbond hydroentangled nonwovens and a
representative carded thermal bond nonwoven.
[0016] FIG. 3B graphically shows the performances of the nonwovens
of FIG. 3A, juxtaposed with the performance of additional
hydroentangled nonwovens.
[0017] FIG. 4A graphically shows performances of various basis
weights of representative hydroentangled spunbond nonwovens and a
representative carded thermal bond nonwoven, having been normalized
to consider the basis weight.
[0018] FIG. 4B graphically shows representative performances of the
nonwovens of FIG. 4A, juxtaposed with the performance of additional
hydroentangled nonwovens, again having been normalized to consider
the basis weight.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Referring to FIGS. 1A-1B, a cleaning sheet (10) according to
the present invention may comprise two, three or more plies. The
plies may be joined together in a face-to-face relationship to form
a laminate. A first ply may be a floor contacting layer (12).
[0020] If desired, the cleaning sheet (10) may be
pre-moistened/pre-wetted [the terms being used interchangeably
herein]. If the cleaning sheet (10) is pre-moistened, it is
preferably pre-moistened with a liquid which provides for cleaning
of the target surface, such as a floor, but yet does not require a
post-cleaning rinsing operation. The cleaning sheet (10) may have
the liquid added during manufacture or after the sheets are placed
in a liquid impermeable container.
[0021] The pre-moistened cleaning sheet (10) may comprise natural
or synthetic fibers. The fibers may be hydrophilic, hydrophobic or
a combination thereof, provided that the cleaning sheet (10) is
generally absorbent to hold, and express upon demand, a cleaning
solution. In one embodiment, the cleaning sheet (10) may comprise
at least 50 weight percent or at least 70 weight percent cellulose
fibers, such as air laid SSK fibers. If desired, the cleaning sheet
(10) may comprise plural layers to provide for scrubbing, liquid
storage, and other particularized tasks for the cleaning
operation.
[0022] Examining the invention in more detail, the floor layer (12)
may comprise a hydroentangled spun bond [HESB] nonwoven. A spunbond
nonwoven comprises sheet materials in which fibers are extruded in
molten state through fine capillaries of a spinneret. The extruded
fibers may be quenched and deposited onto a collecting surface. The
fibers may be generally continuous with a denier ranging from 0.3
to 10 grams per 9000 meters. A particularly suitable denier range
for the present invention is from 1 to 4, particularly 1.7 grams
per 9000 meters. Spunbond fibers may be made according to U.S. Pat.
Nos. 3,341,394; 3,502,358; 3,802,817 and/or 4,340,563.
[0023] A hydroentangled nonwoven comprises sheet materials in which
fibers can be wet laid or dry laid onto a forming screen. The
forming screen may be textured, to provide a dimensional texture to
a macroscopically monoplanar web or may be flat. The fibers can be
entangled together by fine water jets directed towards the web. The
nonwoven sheet is then dried.
[0024] The floor layer (12) may have a basis weight of 20 to 60
gsm, or 30 to 50 gsm, and particularly 35 gsm. Suitable nonwoven
suppliers include Suominen of Helsinki, Finland and Avgol Nonwovens
of Tel-Aviv, Israel.
[0025] The core layer (12) may comprise an airlaid. The airlaid may
be multi-bonded, i.e. comprising both adhesive and/or thermal bonds
to hold the fibers together in a cohesive layer. The core layer
(12) may comprise both naturally occurring cellulose and synthetic
fibers. The optional cellulose component of the core may comprise
wood pulp, particularly=soft wood, hard wood, CTMP, eucalyptus. The
optional synthetic component of the core may comprise PP, PE, PET
or other polyolefinic fibers. The fibers may be bicomponent,
comprising a PE sheath and PET core. The synthetic fibers may have
a nominal length of less than 6 mm or 3 mm or less. The core may
comprise 80 to 90 weight percent cellulosic fibers and balance
synthetic fibers.
[0026] The core layer (12) may comprise a latex binder. The binder
may comprise 1 to 4 or 2 to 3 weight percent latex binder. The core
may have a basis weight of 100 to 170, 110 to 160 or 120 to 140
gsm.
[0027] The optional backing layer (16) may comprise carded thermal
bond [CTB] or [HESB] nonwoven materials. The nonwoven may be made
of PE, PP, PET, Rayon, etc. and have a basis weight of of 20 to 60
gsm, 30 to 50 gsm, and particularly 35 gsm.
[0028] In a degenerate case, the cleaning sheet (10) may use
identical materials for the floor layer (12) and backing layer
(16). This arrangement provides for manufacturing efficiency and
economy of scale.
[0029] The plies of the cleaning sheet (10) may be laminated
together using dynamic mechanical bonding. In such a process, two
or more rolls may be juxtaposed together to form a nip
therebetween. Either or both rolls may have nubs which act against
nubs or face of the opposing roll. The plies are fed through the
nip and optionally autogeneously joined by pressure between the
nubs. The rolls may be operated at equal or unequal surface
velocities. The two or more plies may be joined according to
commonly assigned U.S. Pat. No. 4,919,738; U.S. Pat. No. 6,733,605
and EP 0844062.
[0030] Referring back to the aforementioned US 20070202766/7947613,
the art teaches cumulative volume as a function of increasing pore
radius [FIGS. 1-6]. But this teaching falls short of commercial
feasibility if the desired pore radius is not commercially
available.
[0031] For example and referring to FIGS. 2A-2B, pore radius for
two illustrative and suitable commercially available Avspun
nonwovens, available from Avgol are shown. FIG. 2A shows a pore
radius clustered around 40 microns for a 35 gsm HESB. FIG. 2B shows
a pore radius clustered around 35 microns for a 45 gsm HESB. One of
skill, seeking to use the teachings of the prior art may not be
able to do so, in a cost effective manner --due to lack of
commercial availability of the desired materials. Another approach
is needed.
[0032] FIGS. 3A and 4A show HESB materials from a single vendor,
Avgol [labeled Avspun]. For proof of principle of the invention
described and claimed herein, FIGS. 3B and 4B show the same
information as FIGS. 3A and 4A, and further consider a second
vendor, First Quality Nonwovens [labeled FQN HESB]. Carded thermal
bond material from Suominen [labeled CTB] is shown as a single
datum point.
[0033] Referring to FIG. 3A, it is seen that cleaning mileage
generally increases as a function of basis weight, particularly
when carded thermal bond [CTB] materials are not considered.
Cleaning mileage is determined by mopping a pre-determined test
floor area with constant strokes under increasing pressures, until
the floor sheet expresses less than 0.3 grams fluid loss per 0.3
square meters.
[0034] Referring to FIG. 3B, it is seen that the Avspun materials
generally outperform FQN HESB materials at constant basis weight.
Thus referring to the prior art and FIGS. 3A-3B, one of skill
trying to decouple cost [basis weight] and cleaning performance
[mileage] would seek to use higher basis weight material
[sacrificing cost] or seek to use particular pore volumes [of
unknown performance and commercial availablility]. Yet another
approach is needed.
[0035] Referring to FIGS. 4A-4B, another approach, not found in the
cited prior art, is shown. FIG. 4A shows that when the cleaning
performance is normalized for basis weight, the 35 gsm nonwoven
unexpectedly outperforms the 45 gsm nonwoven. This finding is
particularly unexpected, as the 45 gsm nonwoven has 28% more
material than the 35 gsm material. Looking further at FIG. 4A, it
is seen that the 35 gsm nonwoven even unexpectedly outperforms the
50 gsm nonwoven having 43% more material.
[0036] Looking further at FIG. 4B it is further unexpectedly shown
that FQN HESB materials perform, on a normalized basis, comparable
to or with slightly less efficacy than Avspun materials having
similar, if not more, basis weight/cost. For example, the 45 gsm
FQN HESB and 45 gsm Avspun materials have similar normalized
mileage. This mileage is unexpectedly comparable to the 50 gsm
Avspun mileage. Even more unexpected, the 38 gsm FQN HESB and 35
gsm Avspun materials exhibit even greater performance on a
normalized basis. Such results are not predicted by the art.
[0037] Thus, considering FIGS. 3B and 4B in combination may produce
that performance improvements may not be recognized by searching
for and selecting a particular supplier. Yet another approach is
needed.
[0038] Thus one of skill, seeking to reduce cost, without
sacrificing performance, may use a spun bond or particularly a
hydroentangled spunbond nonwoven material for the floor layer (12)
of a cleaning sheet (10). One of skill might not use a carded
thermal bond nonwoven material.
[0039] Likewise, one of skill might select a nonwoven material
having a cumulative volume at 204 mm H.sub.2O [0.3 psi] of 2-2.7,
2.3-2.5 or 2.3 cubic millimeters per mg of nonwoven material. The
nonwoven may have a basis weight of 25 to 60 gsm, 35-50 gsm or
38-45 gsm.
[0040] The cleaning sheet (10) may be loaded with at least 3-4,
particularly 6-8 grams of cleaning solution per gram of dry
substrate, but typically not more than 10 grams per gram. The
cleaning solution may comprise a surfactant, such as APG surfactant
which minimizes streaking since there is typically not a rinsing
operation during floor cleaning. The cleaning solution may contain
agglomerating chemicals, disinfectants, bleaching solutions,
perfumes, secondary surfactants etc. A suitable pre-moistened
cleaning sheet (10) maybe made according to the teachings of
commonly assigned U.S. Pat. Nos. 6,716,805; D614,408; D629,211
and/or D652,633.
[0041] One of skill is commonly aware that CTB nonwovens are
generally more expensive than comparable spunbond nonwovens. And it
would be expected that a higher basis weight nonwoven would perform
better than a less expensive and lower basis weight nonwoven. But
the inventors have unexpectedly found based upon the available
data, that using a relatively low basis weight nonwoven
unexpectedly allows reduced cost and improved performance. The
inventors have further unexpectedly found, based upon the available
data, that less expensive spunbond materials exhibit better
performance than more expensive carded thermal bond nonwovens. Both
of these results are unexpected.
Cumulative Pore Volume Test Method
[0042] The following test method is conducted on samples that have
been conditioned at a temperature of 23.degree. C..+-.2.0.degree.
C. and a relative humidity of 45%.+-.10% for a minimum of 12 hours
prior to the test. All tests are conducted under the same
environmental conditions and in such conditioned room. Discard any
damaged product. Do not test samples that have defects such as
wrinkles, tears, holes, and like. All instruments are calibrated
according to manufacturer's specifications. Samples conditioned as
described herein are considered dry samples (such as "dry fibrous
sheet") for purposes of this invention. At least four samples are
measured for any given material being tested, and the results from
those four replicates are averaged to give the final reported
value. Each of the four replicate samples has dimensions of 55
mm.times.55 mm.
[0043] One of skill understands that obtaining a suitable sample of
ply from an article comprising multiple ply sheets and/or cleaning
solution will involve several preparation steps, which may include
the removal of all cleaning fluid and the separation of the various
ply sheets from each other and from other components of the
finished article. Furthermore, one of skill understands it is
important to ensure the preparation does not damage the ply being
tested or alter the measured pore volume characteristics.
[0044] Pore volume measurements are made on a TRI/Autoporosimeter
(Textile Research Institute (TRI)/Princeton Inc. of Princeton,
N.J., U.S.A.). The TRI/Autoporosimeter is an automated
computer-controlled instrument for measuring pore volume
distributions in porous materials (e.g., the volumes of different
size pores within the range from 1 to 1000 .mu.m effective pore
radii). Computer programs such as Automated Instrument Software
Releases 2000.1 or 2003.1/2005.1; or Data Treatment Software
Release 2000.1 (available from TRI Princeton Inc.), and spreadsheet
programs are used to capture and analyse the measured data. More
information on the TRI/Autoporosimeter, its operation and data
treatments can be found in the paper: "Liquid Porosimetry: New
Methodology and Applications" by B. Miller and I. Tyomkin published
in The Journal of Colloid and Interface Science (1994), volume 162,
pages 163-170, incorporated here by reference.
[0045] As used in this application, porosimetry involves recording
the increment of liquid that enters or leaves a porous material as
the surrounding air pressure changes. A sample in the test chamber
is exposed to precisely controlled changes in air pressure. As the
air pressure increases or decreases, different size pore groups
drain or absorb liquid. Pore-size distribution or pore volume
distribution (PVD) can further be determined as the distribution of
the volume of uptake of each pore-size group, as measured by the
instrument at the corresponding pressure. The pore volume of each
group is equal to this amount of liquid, as measured by the
instrument at the corresponding air pressure. Total cumulative
fluid uptake is determined as the total cumulative volume of fluid
absorbed. The effective radius of a pore is related to the pressure
differential by the relationship:
Pressure differential=[(2).gamma. cos .THETA.]/effective radius
[0046] where .gamma.=liquid surface tension, and .THETA.=contact
angle.
[0047] This method uses the above equation to calculate effective
pore radii based on the constants and equipment controlled
pressures.
[0048] The automated equipment operates by changing the test
chamber air pressure in user-specified increments, either by
decreasing pressure (increasing pore size) to absorb liquid, or
increasing pressure (decreasing pore size) to drain liquid. The
liquid volume absorbed or drained at each pressure increment is the
cumulative volume for the group of all pores between the preceding
pressure setting and the current setting. The TRI/Autoporosimeter
reports the pore volume contribution to the total pore volume of
the specimen, and also reports the volume and weight at given
pressures and effective radii. Pressure-volume curves can be
constructed directly from these data and the curves are also
commonly used to describe or characterize the porous media.
[0049] For purposes herein, the TRI/Autoporosimeter, uses a liquid
having 0.1 weight % solution of octylphenoxy polyethoxy ethanol
(Triton X-100, a non-ionic surfactant available from Union Carbide
Chemical and Plastics Co. of Danbury, Conn.) in distilled water.
The instrument settings and constants used are: p (density)=1
g/cm3; .gamma. (surface tension)=30 dynes/cm2 and cos
.THETA.=1.degree.. A 9 mm diameter, 1.20 .mu.m pore size Millipore
mixed cellulose filter (Millipore Corporation of Bedford, Mass.;
Catalog # RAWP09025) is employed on the test chamber's porous
plate. Other instrument settings include: The Maximum Sample
Thickness is set to 1.5 mm; Save Kinetics is set to Yes; Chamber
Height is set to 6.4 mm plate; Thickness Measurement is set to Yes;
Number of cycles is 1; Intervals is set to 30 sec.; equilibrium
balance or limit balance rate is set at 15 mg/minute. No stop
radius is specified;
[0050] A blank condition (no sample between plexiglass plate and
Millipore Filter) is run to account for any surface and/or edge
effects within the test chamber. Any pore volume measured for this
blank run is subtracted from the applicable pore grouping of the
test sample. For the test samples, a 4 cm.times.4 cm plexiglass
plate weighing about 32 g (supplied with the instrument) is placed
on the sample to ensure the sample rests flat on the Millipore
filter during measurement. No additional weight is placed on the
sample. The sequence of pressures to be run in the test, in mm
H.sub.2O is as follows: 613, 61, 47, 38, 32, 26, 20, 8, 10, 12, 15,
20, 31, 34, 38, 44, 51, 61, 68, 77, 88, 94, 102, 111, 123, 136,
153, 175, 204, 245, 306, 408, and 613.
[0051] These pressure values are used to produce the Advancing 1
and Receding 1 curves. This sequence starts with the sample dry,
saturates it as the pressure decreases (i.e., Advancing 1 curve),
and then subsequently drains the fluid out as the pressure
increases again (i.e., Receding 1 curve).
[0052] The TRI/Autoporosimeter measures the cumulative weight (mg)
of liquid at each pressure level, and reports the respective
cumulative pore volume of the sample. From these data and the
weight of the original dry sample, the ratio of cumulative pore
volume/sample weight can be calculated at any measured pressure
level, and reported in mm.sup.3/mg. In the case of this test
method, the cumulative pore volume is determined at the pressure of
204 mm H.sub.2O during the Receding 1 curve, and is reported in
mm.sup.3/mg and taken from the TRI instrument.
[0053] Optionally, the pre-moistened cleaning sheet (10) may
further comprise a scrubbing strip (18). A scrubbing strip (18) is
a portion of the cleaning sheet (10) which provides for more
aggressive cleaning of the target surface. A suitable scrubbing
strip (18) may comprise a polyolefinic film, such as LDPE, and have
outwardly extending perforations, etc. The scrubbing strip (18) may
be made and used according to commonly assigned U.S. Pat. Nos.
8,250,700; 8,407,848; D551,409 S and/or D614,408 S.
[0054] The cleaning sheet (10) according to the present invention
may be used with a stick-type cleaning implement [not shown]. The
cleaning implement may comprise a head for holding the cleaning
sheet (10) and an elongate handle articulably connected thereto.
The handle may comprise a metal or plastic tube or solid rod.
[0055] The head may have a downwardly facing surface, to which the
sheet may be attached. The downwardly facing service may be
generally flat, or slightly convex. The head may further have an
upwardly facing surface. The upwardly facing surface may have a
universal joint to facilitate connection of the elongate handle to
the head.
[0056] The upwardly facing surface may further comprise a
mechanism, such as resilient grippers, for removably attaching the
cleaning sheet (10) to the implement. Alternatively, a hook and
loop system may be used to attach the cleaning sheet (10) to the
head. If grippers are used with the cleaning implement, the
grippers may be made according to commonly assigned U.S. Pat. Nos.
6,305,046; 6,484,346; 6,651,290 and/or D487,173.
[0057] If desired, the cleaning implement may have an axially
rotatable beater bar and/or vacuum type suction to assist in
removal of debris from the target surface. Debris removed from the
target surface may be collected in a dust bin. The dust bin may be
mounted within the head, or, alternatively, on the elongate
handle.
[0058] A suitable stick-type cleaning implement may be made
according to commonly assigned U.S. patents Des. 391,715; D409,343;
D423,742; D481,184; D484,287; D484,287 and/or D588,770. A suitable
vacuum type cleaning implement may be made according to the
teachings of U.S. Pat. Nos. 7,137,169, D484,287 S, D615,260 S and
D615,378 S. A motorized implement may be made according to commonly
assigned U.S. Pat. No. 7,516,508. The implement may utilize steam
for cleaning according to jointly assigned US publication
2013/0319463.
[0059] The dimensions and values disclosed herein are not to be
understood as being strictly limited to the exact numerical values
recited. Instead, unless otherwise specified, each such dimension
is intended to mean both the recited value and a functionally
equivalent range surrounding that value. For example, a dimension
disclosed as "40 mm" is intended to mean "about 40 mm."
[0060] Every document cited herein, including any cross referenced
or related patent or application, is hereby incorporated herein by
reference in its entirety unless expressly excluded or otherwise
limited. The citation of any document is not an admission that it
is prior art with respect to any invention disclosed or claimed
herein or that it alone, or in any combination with any other
reference or references, teaches, suggests or discloses any such
invention. Further, to the extent that any meaning or definition of
a term in this document conflicts with any meaning or definition of
the same term in a document incorporated by reference, the meaning
or definition assigned to that term in this document shall
govern.
[0061] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
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