High efficiency vacuum cleaner bags

A novel vacuum cleaner bag is disclosed comprising a closed receptacle having an inlet orifice, the bag being formed from a sheet containing at least 65% flashspun polyolefin fibers. The vacuum cleaner bag is suitable for conventional vacuum cleaners and provides efficient removal of particulate matter, especially soil particles less than 10 microns in size.

FIELD OF INVENTION 
The present invention concerns novel vacuum cleaner bags suitable for use 
in conventional vacuum cleaners and adapted to provide efficient removal 
of particulate matter commonly found in carpets, floors made of wood, 
linoleum, plastic tile, ceramic tile, etc., upholstery, drapes and the 
like. More specifically, the present invention relates to vacuum cleaner 
bags especially adapted to capture particles as small as 1 micron, or even 
smaller, that are present on the aforementioned surfaces. Most 
specifically, the present invention concerns vacuum cleaner bags 
fabricated from flashspun polymeric materials, especially polyolefins, in 
particular polyethylene. 
BACKGROUND OF THE INVENTION 
Traditionally, vacuum cleaner bags have been fabricated from a relatively 
porous cellulosic, i.e., paper, substrate. Vacuuming efficiency is good 
with such paper vacuum bags, that is, the soil is removed from the surface 
being vacuumed. However, vacuuming efficiency, according to this 
definition, is more a function of the vacuum force generated by the vacuum 
cleaner than a measure of vacuum bag performance. 
The paper substrates are sufficiently porous to permit an air flow through 
the clean bag of about 25 to 50 cubic feet per minute (cfm) per square 
foot of substrate and are adequate to retain particulate matter of above 
10 microns. This accounts for most of the weight of the soil to be 
vacuumed. However, because the paper vacuum bag is porous, the smaller 
particles initially pass through the paper vacuum bag medium. As a result, 
the smaller particles, that is, "dust," is exhausted into the air from the 
vacuum itself. This can be observed by viewing the exhaust of the vacuum 
backlighted by sunlight. Indeed, it is not uncommon for there to be dust 
covering furniture in a room previously dusted prior to vacuuming. 
During use, the pores of the paper vacuum bag become plugged with particles 
of dirt. As one might expect, the plugging of the pores of the paper 
vacuum bag assists in capture of the smaller particles. However, this 
occurs only after several uses of the vacuum, and often when the bag has 
been filled to a significant degree. Moreover, at least until the paper 
vacuum bag is quite plugged, the inherent porosity of this filter medium 
permits the particles entrapped in its pores to be dislodged and replaced 
by similarly sized particles, a phenomenon known as seepage penetration 
The effect, then, is the same--the smaller particles are exhausted into 
the atmosphere. 
The reentry of small particles of less than about 10-20 microns into the 
vacuumed room is, of course, irksome because the room has not been cleaned 
meticulously. However, the particles of less than about 20 microns include 
pollen (about 20 microns), skin scale (about 15 microns), spores (0.25 to 
3 microns), fungi (about 2 microns), bacteria (0.25 to 2 microns) and fair 
amounts of dust (5-100 microns). These air contaminants cause serious 
allergies or occasion the transmittal of various diseases, e.g., flu. 
Accordingly, the removal or reduction of such finely sized contaminants 
from the vacuumed surface without releasing them through the vacuum 
cleaner exhaust is particularly desirable. Indeed, these particles are 
better left on the surface being vacuumed than releasing them into the 
atmosphere. 
Attempts have been made to provide vacuum cleaner bags which are better in 
retaining the smaller particles within the bag, and not exhausting them 
into the atmosphere. 
Thus, U.S. Pat. No. 4,589,894 to Gin discloses a vacuum cleaner bag of 
three ply construction comprising (a) a first outer support layer of 
highly porous fabric formed of synthetic fibers, the fabric having an air 
permeability of at least 100 m.sup.3 /min/m.sup.2 ; (b) an intermediate 
filter layer formed of a web comprising randomly interentangled synthetic 
polymeric microfibers that are less than 10 microns in diameter, has a 
weight of 40 to 200 g/m.sup.2, and an air permeability of about 3 to 60 
m.sup.3 /min/m.sup.2, and (c) a second outer support layer disposed on the 
opposite side of the web having an air permeability of at least 50 m.sup.3 
/min/m.sup.2. The web of the Gin vacuum cleaner bag may be made by 
melt-blown or solution-blown processes. Illustratively, the Examples 1-7 
in Gin describe use of melt-blown polypropylene as the web ply and nylon 
or spun-bonded polypropylene as the support plys. 
Another multiply filter medium useful for vacuum cleaner bags is disclosed 
in U.S. 4,917,942 to Winters. The laminate structure of Winters comprises 
a porous layer of self-supporting nonwoven fabric having an air 
permeability of 300 m.sup.3 /min/m.sup.2 and a layer of randomly 
intertangled nonwoven mat of electret-containing microfibers of synthetic 
polymer coextensively deposited on and adhered to the self-supporting 
nonwoven fabric. The self-support layer is, preferably, a spun-bonded 
thermoplastic polymer. The electret-containing mat is preferably based on 
a melt-blown polyolefin. 
The melt-blown polyolefin fiber webs used by Gin and Winters as the filter 
medium are disadvantageous in that they have little structural strength. 
Thus, they are characterized by poor tensile and tear strengths, and 
cannot be fabricated into a usable vacuum cleaner bag independent of the 
supporting scrims. This adds to the cost of the vacuum cleaner bag, which 
is, of course, undesirable. Moreover, these fibers do not lend themselves 
to vacuum cleaner bag fabrication utilizing the type of equipment used 
commonly in the manufacture of vacuum cleaner bags. 
It has been found that a vacuum cleaner bag characterized by excellent 
retention of small particles of 10 microns or less can be fabricated from 
a sheet of flashspun polyolefin fibers. This flashspun sheet, described in 
greater detail below with respect to its manufacture and properties, has 
excellent strength. Accordingly, vacuum cleaner bags of the present 
invention can be fabricated from a sheet of this material, and without the 
requirement for a supporting scrim. Moreover, this material, which 
comprises ultra-short fibers of micro diameter, can be fabricated into a 
nonwoven substrate with a process analogous to the manufacture of 
cellulosic substrates, which account for the majority of vacuum cleaner 
bags currently sold. Advantageously, these flashspun sheets have a uniform 
effective pore size distribution which permits their utilization as a 
vacuum cleaner bag without substantial decay in air permeability 
throughout its normal use--i.e., until the vacuum cleaner bag of the 
present invention has been essentially filled. 
SUMMARY OF INVENTION 
It is an object of the present invention to provide a vacuum cleaner bag 
fabricated from a sheet of flashspun polyolefin. 
It is a further object of the invention to provide a vacuum cleaner bag 
that is suitable to enhance retention of small particles less than 10 
microns in diameter, and in particular up to about 1 micron or even less 
in diameter, within the vacuum cleaner bag. 
It is a primary object of the present invention to provide a vacuum cleaner 
bag adapted to reduce appreciably the population of particles between 1 to 
10 microns present in the outlet air leaving the vacuum cleaner, that is, 
to capture and retain such particles in the vacuum cleaner bag. 
These and other benefits and advantages of the invention will be more fully 
understood upon reading the detailed description of the invention, a 
summary of which follows. 
The vacuum cleaner bags of the present invention are suitable for use with 
a vacuum cleaner device or system having a vacuum inlet tube attachable at 
one end to the vacuum cleaner bag. The vacuum cleaner bag comprises a 
closed receptacle having a vacuum inlet tube attachment orifice, the 
receptacle being formed from a sheet containing at least 65% ultra-short 
flashspun polyolefin fibers, and means affixed to the receptacle for 
attachment of the vacuum inlet tube within the orifice. Preferably, the 
vacuum cleaner bags comprise a sheet containing more than 75% of the 
ultra-short flashspun fibers, most preferably more than 90% of such 
fibers. In particular, the vacuum cleaner bags of the present invention 
are fabricated from a sheet comprising essentially 100% ultra-short 
flashspun fibers. 
The vacuum cleaner bag is characterized by having such strength as to 
permit its construction from the flashspun polyolefin sheet and not to 
require further structural support such as a scrim joined to the sheet. 
The flashspun sheet is also sufficiently durable as to resist undue 
wearing during normal vacuuming. The flashspun polyolefin sheet material 
from which the vacuum cleaner bag is made has an air permeability, when 
new, of at least about 2, preferably 5-20, most preferably 5-12 
cfm/ft.sup.2. It has been found that the vacuum cleaner bags of the 
present invention are especially resistant to plugging or blinding by 
small-sized particles. Accordingly, the vacuum cleaner bags retain 
sufficient air permeability during vacuuming to maintain their cleaning 
capability until the vacuum cleaner bag is essentially full.

DETAILED DESCRIPTION OF THE INVENTION 
The vacuum cleaner bag of the present invention employs as the filter 
medium a sheet made from flashspun polyolefin fibers, the sheet being 
characterized by its ability to effectively reduce the level of small 
sized dirt particles, including dust, spores, pollen, fungi, etc., 
vacuumed from a surface. Typically, the dirt particles of interest have a 
size in the range of less than about 10 microns, with particles of 1 to 10 
microns being especially difficult to remove with conventional paper 
vacuum cleaner bags. Indeed, the vacuum cleaner bags of the present 
invention have been found to be effective with respect to even smaller 
sized particles. 
Moreover, the flashspun polyolefin sheets are further characterized by 
their strength. Accordingly, the vacuum cleaner bags of the present 
invention do not require a supporting scrim, which only serves to multiply 
the number of processing steps needed during manufacture. 
The flashspun fibers suitable for use in the manufacture of the vacuum 
cleaner bags of the present invention are made by preparing a mixture of 
volatile solvent and molten polyolefin polymers, which mixture is forced 
through an extruder with subsequent rapid evaporation of the solvent to 
produce relatively continuous polyolefin fibers having a micro-fine fiber 
diameter distribution in the range of 0.5 to 20 microns. These continuous 
fibers are then refined to provide ultra-short fibers. Suitably, these 
fibers have a length of less than about 6, preferably from about 0.5 to 
about 2 mm. The ultra-short fibers are then dispersed in water to form a 
slurry, which slurry is deposited on a Fourdrinier or inclined wire. The 
slurry also contains a low concentration, from about 0.1 to about 5%, of a 
binding agent such as polyvinyl alcohol. A sheet of relatively low 
strength is obtained by virtue of the mechanical entanglement of these 
ultra-short, small-diameter fibers, upon removal of the water and drying. 
Thereafter, the flashspun fiber sheet is further treated by a hot bonding 
procedure, which, due to the thermal joining of at least a portion of the 
fibers, imparts significant strength to the flashspun fiber sheet. It is 
Applicants' understanding that the process for forming flashspun 
polyolefin sheets as described above is set forth in EPA 292,285 assigned 
to DuPont, published Nov. 23, 1988, incorporated herein by reference 
thereto. 
It is seen that the latter portion of the process wherein the flashspun 
fiber sheet is made is analogous to conventional paper making. 
Accordingly, existing or modified processing equipment is suitable and 
processing is within the understanding of existing personnel. 
The former portion of the process--the preparation of the short fibers--is 
quite advantageous in certain respects. First, the refining process 
provides control over the length of the fibers to be used in manufacture 
of the flashspun sheet. Second, and collaterally, the shortness of the 
fibers obtained considerably increases the uniformity, and hence the 
strength of the sheet produced. Unlike meltblown webs, which comprise 
rather long fibers, the flashspun fibers can network in three dimensions 
in view of their ultra-short length. The third, most critical benefit, is 
the very high fiber surface area per unit weight of fiber afforded the 
sheet by the processing. Thus, the flashspun fibers in the sheet have a 
fiber surface area per unit weight of at least about 2, preferably at 
least about 2.5, most preferably at least about 3.5 m.sup.2 /g. In 
comparison, the fibers present in a typical meltblown polyolefin web has a 
surface area per unit weight of fiber of less than about 1.5 m.sup.2 /g. 
In considering the flashspun polyolefin sheets for their suitability as the 
construction material for a vacuum cleaner bag, various parameters were 
identified that affect cleaning efficiency. In particular, the ability of 
the flashspun sheets to substantially remove particles in the &lt;10 micron 
range was investigated. 
Thus, it is believed that the particle capture efficiency was improved with 
the vacuum cleaner bags of the present invention in view of their 
particularly effective pore size distribution of substantial uniformity 
across the surface of the sheet. In defining this parameter, the term 
"effective" is used, inasmuch as the pores are irregular in geometry. The 
effective pore size distribution, in turn, is a function of fiber diameter 
and fiber length, which together define fiber surface area of a given 
weight of fiber. 
Suitable diameter, length and surface area characteristics of the fibers 
used to make the flashspun sheet material used in the manufacture of the 
vacuum cleaner bags of the present invention, are tabulated below: 
TABLE I 
______________________________________ 
Most 
Broad Preferred Preferred 
______________________________________ 
Fiber diameter 0.5-20 0.5-15 0.5-10 
distribution, .mu. 
Fiber length, mm 
0.1-6.0 0.5-2.0 0.5-1.5 
Fiber surface area, m.sup.2 /g 
&gt;2 &gt;2.5 &gt;3.5 
______________________________________ 
As a practical matter, fiber surface areas above about 6 m.sup.2 /g are 
difficult to achieve. However, this should not be regarded as an upper 
limit, inasmuch as increasing fiber surface area improves particle capture 
efficiency. 
Each of these fiber parameters affect particle capture efficiency. Thus, 
particle capture efficiency has been found to increase with decreasing 
fiber length and decreasing fiber diameter, which increases fiber surface 
area for a given weight of fiber present in the sheet. These parameters 
influence the effective pore size distribution of the sheet. 
Table II, below, sets forth the effective pore size distribution of the 
flashspun sheets as measured by a Coulter Porometer. Moreover, the pores 
of the flashspun sheet are especially uniform over their surface. 
TABLE II 
______________________________________ 
Effective Cumulative Percent 
Pore Size Most 
Distribution, .mu. 
Broad Preferred 
Preferred 
______________________________________ 
&gt;30 1 0.1 0 
&gt;20 5 2 0.5 
&gt;10 90 50 2.5 
&lt;10 and above 
100 100 100 
______________________________________ 
The caliper of the flashspun sheet for use in the vacuum cleaner bags of 
the present invention is from about 5 to about 25, preferably from about 8 
to about 15 mil. Below a caliper of about 5 mil, the strength of the of 
the flashspun sheet is usually too low for the construction of a 
"stand-alone" vacuum cleaner bag, that is, a vacuum cleaner bag in which a 
support scrim is unnecessary. Above about 25 mil, the caliper of the web 
is too high, and may negatively affect the air permeability of the sheet. 
The vacuum cleaner bag material, when clean, should have an air 
permeability of at least about 2 cfm/ft.sup.2. Preferably, air 
permeability is in the range of 5 to 20 cfm/ft.sup.2, most preferably 5 to 
12 cfm/ft.sup.2. An air permeability of less than about 2 cfm is deemed to 
be the lower practical limit for vacuum cleaner bags for use with 
household vacuum cleaners. Thus, at such air permeability, the motor of 
the vacuum must overcome the higher pressure drop through the vacuum 
cleaner bag. Above about 25 cfm air permeability, the sheet is too porous 
to effectively remove the smaller particles of less than about 10 microns. 
The lower portion of the air permeability range is significantly lower than 
that typically considered necessary for the conventional paper vacuum 
cleaner bag. This is because the large pores of the conventional paper 
vacuum cleaner bags are prone to blinding, that is, plugging. Thus, during 
use, there is a decay in the porosity of the paper vacuum cleaner bags 
with resulting decrease in air permeability. The vacuum cleaner bags of 
the present invention, made with the flashspun sheet as previously 
indicated, appear to be substantially less prone to blinding during use. 
That is, Applicants have experienced no reduction in the ability of the 
vacuum cleaner bags to pick up debris from the surface being vacuumed 
until the vacuum cleaner bag is essentially full. This is surprising 
inasmuch as the clean vacuum cleaner bag of the present invention has an 
inherently low air permeability. Thus, it is believed that the air 
permeability of the vacuum cleaner bags of the present invention is 
relatively constant with use during the normal life of the bag--i.e., 
until the bag is full. Of course, the pressure drop through the vacuum 
cleaner bag does increase as the bag fills because of the loss in bag 
surface area attributable to filling. 
Tests with meltblown vacuum cleaner bags have indicated that they are 
appreciably less resistant to blinding as compared to the flashspun sheet 
and somewhat less resistant to blinding as compared to paper. Furthermore, 
because the meltblown webs are inherently weak, it is important to 
minimize wear occasioned by high pressure differentials across the surface 
of such web. Accordingly, it is disadvantageous to use meltblown webs 
having a low air permeability. On the other hand, the flashspun material 
has excellent strength and wear resistance, and poses no difficulty, 
notwithstanding a possibly low air permeability. 
In addition, the flashspun material employed in the manufacture of the 
vacuum cleaner bags of the present invention has other properties which 
are desirable. Thus, the flashspun sheet has a low surface coefficient of 
friction, which is one factor that makes it resistant to blinding. 
Further, the flashspun material is hydrophobic. Accordingly, it has good 
wet strength. Thus, the inadvertent suction of spills or vacuuming of damp 
carpets is less likely to damage the vacuum cleaner bag. 
The typical properties of the flashspun sheet used to make the vacuum 
cleaner bags of the invention are reported in Table III. 
TABLE III 
______________________________________ 
Test Method 
Range Preferred 
______________________________________ 
Mullen Bursting Strength, psi 
ASTM D 774 &gt;15 30-50 
Tongue Tear, lb/in 
ASTM D2261 &gt;0.05 0.1-0.3 
Break Strength, lb/in 
ASTM D1682 &gt;10 15-25 
Elongation, % ASTM D1682 &gt;3 5-20 
Puncture Resistance, lb-in/in.sup.2 
ASTM 3420 &gt;3 6-10 
Surface Coefficient of 
TAPPI T 503 
&lt;50 &lt;40 
Friction (Slip Angle), degrees 
______________________________________ 
Each of these properties provide for an exceptionally useful material for 
use in the vacuum cleaner bags of the present invention. 
The vacuum bags may be fabricated in the myriad of geometries needed for 
the various types and models of vacuum cleaners. The two principal types 
of vacuum cleaners are the upright and canister types. The upright vacuum 
cleaner uses an elongated vacuum cleaner bag, while the canister vacuum 
cleaner uses a short bag that is generally somewhat longer than it is 
wide. Vacuum cleaner bags suitable for a central vacuum system may also be 
made. 
The upright comes in two styles--a top fill bag having a vacuum inlet tube 
connection opening proximate the top of the bag, and a bottom fill wherein 
one end is open for connection to the vacuum inlet tube located proximate 
the bottom of the vacuum cleaner. Generally, the upright type of vacuum 
cleaner also has a porous outer bag made of vinyl, cloth or vinyl-coated 
cloth, the vacuum bag residing therewithin. The outer bag serves as 
protection for the vacuum cleaner bag, and does not participate to any 
significant degree in the capture of the soil particles. In some models, 
especially older models, the upright vacuum has a "blow-back" feature, 
which permits the air stream entering the vacuum to bypass the vacuum bag. 
In most newer models, the motor is protected by a trip switch which shuts 
off the motor, as when the inlet tube is clogged or the bag is completely 
full. 
FIGS. 1 and 2 illustrate a top fill vacuum cleaner bag 10 suitable for use 
with an upright vacuum cleaner. 
The upright bag 10 is a receptacle of unitary construction comprising a 
single sheet 20 of the flashspun polyolefin material, as best illustrated 
in FIG. 2. FIG. 2 is a cross-sectional view of the bag shown in FIG. 1, 
across lines 2--2. The caliper or thickness of the sheet 20 shown in FIG. 
2 has been greatly enlarged in order to clearly illustrate the 
construction of the bag 10. The single sheet 20 is formed into an 
elongated cylinder by joining the ends 22 and 23 of sheet 20 along their 
length at interfacial surface 24. Sufficient sheet material is retained 
between sidewall surfaces 25 and 26 to permit formation of one or more 
pleats or gussets. In the bag shown in FIGS. 1 and 2, a single gusset is 
illustrated, formed by sidewall segments 27 and 28. It is more typical, 
however, for a bag to have two such gussets. The ends 22 and 23 may be 
joined by a conventional means, for example, adhesively, thermally, or 
mechanically. 
As best shown in FIG. 1, the top and bottom ends 30, 31 of the bag 10 are 
closed simply by wrapping an end over itself, and joining the wrapped ends 
to the front surface 25 or rear surface 26 of the bag. The bag 10 is a top 
fill type. Accordingly, the vacuum inlet tube connection shown generally 
by numeral 15 is proximate to the top of the bag. The connection comprises 
an orifice 33 through the bag and a collar 35 joined to the front surface 
25 of the bag, the collar having an opening which registers with the 
opening 33. 
As clearly illustrated by FIGS. 1 and 2, the vacuum cleaner bag 10 is 
fabricated from a single sheet of the flashspun filter material, and does 
not require a supporting scrim or other supporting structure. This is 
possible in view of properties previously described for the flashspun 
filter material. 
Another top-fill bag 50 is illustrated in FIG. 3, in rear perspective view. 
The construction of this bag is similar to that of the top fill type shown 
in FIGS. 1 and 2, but instead of the vacuum inlet tube connection 15 shown 
in FIG. 1 has a sleeve 55 extending downward from a vacuum bag fill 
orifice 58, shown in the cutaway portion of the rear surface 52 of the bag 
50. The other elements of the bag are identified by the same numerals as 
in FIGS. 1 and 2. The sleeve 55 is connected to the vacuum inlet tube at 
opening 56. The sleeve 55 may be fabricated from impervious paper or other 
suitable material. 
FIG. 4 illustrates a vacuum cleaner bag 100 suitable for use with canister 
vacuum cleaners. 
The vacuum cleaner bags of the present invention may also be provided in 
other geometric shapes, which may be required for vacuums used by 
professional cleaning services Moreover, the vacuum cleaner bags may be 
fabricated for reuse. Thus, in FIG. 1, for example, the bag closure at the 
top end 30 may be made openable by utilizing mechanical closure means, 
such as a zipper, snaps or the like. The bags of the present invention may 
be reused in view of their strength and ability not to blind. 
It should be understood that the flashspun sheets described above may also 
contain minor amount of fibers not made by the flashspun process. 
Generally, the amount of such other fibers should be less than about 35% 
by weight of the total sheet, preferably less than 25%. For example, a 
sheet made containing 80% flashspun polyethylene fibers and 20% continuous 
filament polyester made by a spun bonding process was found to be suitable 
in the manufacture of the vacuum cleaner bags of the present invention. 
The polyester fibers increased air permeability and tensile strength of 
the sheet, but because this sheet also had a greater pore size 
distributionand air permeability, particle capture efficiency was 
sacrificed to some extent. Other types of nonflashspun fibers can be used, 
nonlimiting examples of which are polyamide and polyolefin fibers. Of 
course, in view the above discussion regarding efficiency, care must be 
used when blending these other fibers with the flashspun fibers, both as 
to amount and kind of the nonflashspun fibers. The preferred embodiment of 
the present invention, however, is a vacuum cleaner bag made from a 
flashspun sheet comprising very high proportions, above about 90% 
flashspun fibers. Most preferably, the vacuum cleaner bag is made from a 
sheet containing essentially 100% flashspun fibers. 
It should also be appreciated that the flashspun sheet may be a composite 
sheet comprising two or more flashspun sheets thermally or otherwise 
laminated together. Other posttreatments of the flashspun sheet may also 
be conducted, if desired, provided that such treatments do not adversely 
affect the performance of the vacuum cleaning process. 
Initial tests in accordance with ASTM F 1215-89 were conducted on a 
flashspun polyethylene sheet. This test measured the ability of the 
flashspun sheet to remove one micron particles from an air stream at air 
stream velocities ranging from about 20 to about 100 ft/min. The exhaust 
from a typical vacuum, operating with a clean vacuum cleaner bag, is about 
60 ft/min. The results of the initial testing for various substrates 
tested in accordance with the ASTM procedure are illustrated graphically 
in FIG. 5. The substrates tested are described in greater detail in Table 
IV. 
The initial tests per the ASTM F 1215-89 protocol demonstrated the ability 
of the flashspun sheet to remove about 98% of the one micron particles. 
This compared favorably to paper (as obtained from a commercial Hoover top 
fill upright cleaner bag), which removed only about 60% of the one micron 
particles at 60 ft/min and a fine meltblown web (FMB) which removed about 
82% of the one micron particles. A sheet comprising 80% flashspun fibers 
and 20% polyester fibers (R-70) was able to remove about 86% of the one 
micron particles at 60 ft/min air velocity. 
This test could not, however, predict the suitability of the flashspun 
sheet for its intended purpose as a vacuum cleaner bag. Thus, a typical 
soil to be vacuumed includes particles ranging in size from submicron 
particles to over 1,000 microns, and would also include nonparticulate 
debris, e.g., threads, paper, food residues and small articles. 
Accordingly, the vacuum cleaner bags of the present invention had to be 
tested with regard to typical soils. Moreover, it was yet necessary to 
ensure that the vacuum cleaner bags of the present invention could 
efficiently remove those soil particles less than 10 microns in size. 
Secondly, there was a concern that the low air permeability of the 
flashspun sheet would adversely affect vacuuming efficiency. A 
conventional paper vacuum cleaner bag initially has an air permeability of 
above about 25 cfm/ft.sup.2, which decreases during the vacuuming 
operation. Moreover, as the bag fills, the surface area of the bag 
decreases. The decrease in air permeability and the loss in bag surface 
area eventually result in loss of air flow through the vacuum cleaner and 
into the bag. As a result, the volumetric flow of air through the vacuum, 
and hence the efficiency of vacuuming, decreases, notwithstanding 
continued vacuum motor operation. Eventually, when the pressure drop is 
too great, the vacuum automatically shuts off. The lack of vacuuming 
efficiency is usually noticeable long before this occurs and often before 
a paper vacuum bag is full, the user observing the inability of the vacuum 
to pick up threads, lint, food crumbs and small articles. 
Thus, there was a serious concern that the above-described loss in 
vacuuming efficiency would occur long before the vacuum cleaner bag of the 
present invention was full. Moreover, there was a concern that the low air 
permeability would overtax the motor, with resultant shut-off of the 
vacuum and possibly mechanical problems. 
Accordingly, extensive tests were carried out for the vacuum cleaner bags 
of the present invention. In addition, a Hoover vacuum cleaner bag and a 
vacuum cleaner bag made from meltblown polypropylene were also tested. The 
results of these tests are indicated in the Examples which follow. 
The vacuum cleaner bags tested were made from substrates described in Table 
IV. All of the bags were tested using a Hoover upright vacuum cleaner 
Model No. U-3335 having a top fill vacuum inlet tube connection, which was 
purchased new at the commencement of the tests. 
TABLE IV 
__________________________________________________________________________ 
Fiber/Sheet 
Property Substrate 
__________________________________________________________________________ 
Designation P-16 P-161 
R-70 FMB Hoover 
Source Dupont 
Dupont 
Dupont 
James River 
Hoover 
Type (see (1) (1) (2) (3) (4) 
notes below) 
Fiber Characteristics: 
Diameter Dis- 
0.5-20 
1-20 0.5-40 
10-20 19-40 
tribution, .mu. 
Length (mean), mm 
0.9 0.9 1.5 Long and 
1.1 
continuous 
Surface Area, m.sup.2 /g 
4 4 1.5 1 0.25 
Sheet Characteristics: 
Effective Pore Size 
Distribution, .mu.: 
Maximum 20.9 22.5 27.5 25 69.3 
Mean 7 9.0 12.8 13 18.5 
Minimum 4.3 6.7 8.2 8 9.6 
Caliper, mil 
9 10 11 20 6 
Air Permeability, 
5 9 20 23 25 
cfm/ft.sup.2 
Tongue Tear, lb/in 
0.16 0.2 0.23 0.06 0.09 
Mullen Burst Strength, 
30 35 25 20 25 
psi 
Surface Coefficient 
35 37 41 &gt;100 55 
of Friction, Degrees 
__________________________________________________________________________ 
Notes to Table IV: 
(1) Flashspun polyethylene sheet per the present invention. 
(2) Flashspun polyethylene sheet per the present invention containing 20% 
spunbonded polyester fibers having a fiber diameter up to 40.mu.. 
Composite fiber surface area is specified. 
(3) Fine meltblown (FMB) polypropylene web laminated to a single 
spunbonded polypropylene scrim. 
(4) Hoover vacuum cleaner bag, Type A. 
EXAMPLE 1 
Vacuum cleaner bags made with the substrates identified in Table IV were 
tested in accordance with ASTM F 608, which measures Pickup Efficiency of 
a defined test soil, which sets forth a systematic procedure for assessing 
vacuum cleaner performance. Applicants measured vacuum cleaner performance 
by measuring Pickup Efficiency, which is defined as the weight of the test 
soil retained in the vacuum cleaner divided by the total weight of the 
soil deposited uniformly onto a 6-foot by 4-foot medium shag carpet, 
multiplied by 100. The weight of the soil picked up by the vacuum cleaner 
is obtained by taking the tare weight of the vacuum cleaner before and 
after use. 
The ASTM procedure defines generally how the carpet is to be vacuumed, but 
does not state the length of the vacuuming operation, nor the number of 
runs (e.g., number of soil applications or "soilings") to be sequentially 
conducted. In the tests conducted, it was found that the vacuuming of the 
carpet could be completed satisfactorily according to the ASTM procedure 
in about one minute. The test was conducted consecutively eight times. The 
Pickup Efficiency reported below is based on the tare weights for each of 
the eight trials. In each trial 100 grams of the test soil was deposited 
on the carpet. The test soil is specified in Table V. 
TABLE V 
______________________________________ 
ASTM 
Test Soil Weight 
Composition 
% 
______________________________________ 
Silica Sand, .mu.: 
&gt;420 0.9 
300-419 31.5 
210-299 41.4 
149-209 13.5 
105-148 2.7 
Talc, .mu.: 
&gt;44 0.05 
20-43.9 1.25 
10-19.9 2.7 
5-9.9 2.3 
2-4.9 2.0 
1-1.9 0.8 
&lt;0.9 0.9 
______________________________________ 
Approximately 8.7% of the soil comprised particles less than 20 .mu.. 
Approximately 6% comprised particles less than 10 .mu.. 
The results of these tests are reported in Table VI. 
TABLE VI 
______________________________________ 
Soil 
Application 
Pickup Efficiency, %: 
Number P-16 P-161 R-70 FMB Hoover 
______________________________________ 
1 100.26 100.48 99.06 88.51 98.08 
2 99.3 99.35 98.89 93.28 98.36 
3 98.8 98.41 99.08 96.39 98.20 
4 98.7 98.94 98.91 95.99 98.46 
5 98.4 98.31 98.68 96.30 98.70 
6 98.99 98.04 98.75 96.28 98.03 
7 99.1 97.90 98.46 96.78 97.84 
8 99.01 97.90 98.79 93.81 98.53 
______________________________________ 
This data indicates that the efficiency of the vacuum cleaner bags made 
with each of the materials maintained their Pickup Efficiency during the 
course of the eight trials, although the Pickup Efficiency of the fine 
meltblown mateiral was somewhat less. The bag made from the R-70 sheet 
also performed quite well. 
EXAMPLE 2 
The test of Example 1 was repeated using a simulated household soil (SHS), 
as described in Table VII. 
TABLE VII 
______________________________________ 
SHS Composition Particle Size 
Weight % 
______________________________________ 
Fine Dust See below 6.5 
16 Mesh Sand 1190.mu. 8.0 
20 Mesh Sand 841.mu. 5.0 
40 Mesh Sand 420.mu. 15.0 
70 Mesh Sand 210.mu. 10.0 
Talc Per Table V 
6.5 
Oats and Rice 5.0 
Crackers 3.0 
Thread 3.0 
Paper 4.0 
Yarn 1.0 
Cotton Linters 33.0 
Total 100.0 
Fine Dust Particle Size Distribution 
Nominal Particle Cumulative 
Size, .mu. Percent 
______________________________________ 
&lt;5.5 38 
&lt;11.0 54 
&lt;22.0 71 
&lt;44.0 89 
&lt;176.0 100 
______________________________________ 
This soil was developed by analyzing typical soil samples in vacuumed 
carpets. Approximately 7.4% of the soil comprises soil particles less than 
10 .mu.. 
The results of this test are tabulated below in Table VIII. 
TABLE VIII 
______________________________________ 
Soil 
Application 
Pickup Efficiency, % 
Number P-16 P-161 FMB Hoover 
______________________________________ 
1 91.20 89.6 88.51 87.9 
2 92.0 93.9 93.28 91.1 
3 95.80 93.1 96.39 94.1 
4 96.40 94.4 95.99 94.0 
5 94.70 94.8 96.30 95.1 
6 94.80 95.0 96.21 96.8 
7 96.40 96.9 96.78 96.6 
8 93.00 99.6 93.82 98.4 
______________________________________ 
These results confirm the conclusions reached with respect to Example 1, 
that is, the tested vacuum cleaners are capble of picking up a composite 
soil containing mostly large-sized debris. 
EXAMPLE 3 
Pickup Efficiency as measured in Examples 1 and 2 is seen to be a measure 
of the vacuum cleaner to pick up dirt. As such it is more a measure of the 
vacuum cleaner's suctioning capacity than the particle capture efficiency 
of the vacuum cleaner bag. Thus, the procedure used in Examples 1 and 2 is 
suitable to determine the overall effectiveness of the vacuum cleaner bag 
in removing a soil from a vacuumed surface, but does not adequately 
consider the ability of the vacuum bag to retain small particles. 
Thus, the procedure of Examples 1 and 2 includes in the dirt picked up 
small amounts of dirt not present in the vacuum cleaner bag. Such small 
amounts of dirt would be found, for example, in the vacuum inlet nozzle 
and vacuum inlet tube connection, as well as dirt passing through the 
vacuum bag but retained in the permanent outer bag present on the vacuum 
cleaner. 
Moreover, the procedure, although satisfactory in establishing overall 
trends, is subject to appreciable error in the accurate measurement of 
Pickup Efficiency. This is so because the procedure measures the weight of 
the test soil retained in the vacuum cleaner by obtaining the tare weight 
of the vacuum cleaner before and after vacuuming of the test soil. In view 
of the large mass of the vacuum cleaner as compared to the weight of the 
dirt picked up, the procedure is quite insensitive, especially since the 
total weight of the particles less than 10 .mu. is only 6 g in the case of 
the ASTM soil and about 7.4 g in the case of the SHS soil. 
Accordingly, the ASTM procedure was modified as follows. A Climet particle 
analyzer Model No. CI-7300 was used to measure the particle size 
population of the air exhausted from the vacuum. The analyzer was set to 
determine in the exhaust the number of particles &gt;0.3, &gt;0.5, &gt;0.7, &gt;1.0, 
&gt;5.0 and &gt;10.0 microns. The analyzer inlet nozzle was located 
approximately two feet from the exhaust of the vacuum cleaner. For an 
upright vacuum, the exhaust was considered to be that portion of the outer 
vacuum bag proximate the vacuum inlet tube connection. The analyzer 
provided a printout of the number of particles of the above-identified 
distribution automatically every minute. 
Care was taken during the application of the test soil to the carpet to 
prevent contaminating the air in the room where the test was conducted. 
Sufficient time was given after application of the soil to the carpet to 
allow any airborne soil particles to settle. Vacuuming was commenced when 
the analyzer printout recorded a background population of 250 particles of 
&gt;10.0 microns. As in Examples 1 and 2, the carpet was vacuumed for one 
minute. Thus, the end of vacuuming coincided with the analyzer printout 
for the next one-minute interval. The difference between this analyzer 
reading and the background analyzer reading for each particle size were 
calculated. It should be recognized that, although the particle size 
analyzer operated continuously, the particle size measurements are not 
instantaneous but, rather, are integrated with time over the one-minute 
interval prior to the printout. Vacuum cleaner bugs made from the P-16, 
P-161, FMB and Hoover materials were tested as described above. The SHS 
soil was used in the test. 
The results are illustrated graphically in FIG. 6. Except for the fine 
meltblown vacuum cleaner bag, these results are the average of two 
separate runs using a new vacuum cleaner bag on each run, the separate 
runs being the average of eight sequential trials. The results for the 
fine meltblown are based on a single run of eight averaged sequential 
trials. In each trial the soil applied to the carpet was 100 grams. 
FIG. 7 illustrates these test results as the percentage increase ("Increase 
Factor") of particles of a given size distribution present in the vacuum 
exhaust over the background level for the given size distribution, i.e., 
EQU Increase Factor=[(P.sub.v -P.sub.i)/P.sub.i ].sub.n .times.100 
where 
P.sub.v =the population of particles reported at the end of vacuuming; 
P.sub.i =the population of particles reported in the background 
measurement, and 
n=the given particle size, e.g., &gt;0.3, &gt;0.5, etc. 
Increase Factor is thus a measure of the increase in the number of 
particles of a particle size distribution that became airborne by virtue 
of vacuuming. It is seen from FIG. 6 that vacuuming with a conventional 
paper vacuum cleaner bag increased the &lt;5 micron-sized particles present 
in the exhaust substantial, while the P-16 and P-161 cleaner bags of the 
present invention greatly lowered such sized particles present in the 
exhaust. FIG. 7 shows that relative to paper the reduction in the smaller 
particles is significant. FIG. 7 also shows that the fine meltblown 
material was efficient in preventing the airborne particles from 
exhausting to the atmosphere. However, in testing the vacuum cleaner bags 
beyond the eight sequential soilings per this Example, it was found that 
this fine meltblown bag, as well as others, was particularly prone to 
various types of problems. Typically, the bag failed long before the bag 
was full. The results of such testing is reported in Example 5. 
EXAMPLE 4 
The vacuum cleaner bags of the present invention were tested subjectively 
for their ability to capture fine dust particles. In this test 10 grams of 
Fine Dust (described in Example 2) were applied to the carpet. About 3.5% 
of this soil is less than about 10 .mu.. After allowing the dust to 
settle, the soil was vacuumed. With the lights in the room off and blinds 
drawn, a 500-watt spotlight was focused on the exhaust, in order to 
observe any particles passing through the vacuum bag. In addition, the 
vacuum bags made of paper and fine meltblown polypropylene described in 
Table IV were tested. Finally, a Rainbow vacuum was tested. The Rainbow 
machine, which is used by professional cleaning services, employs a water 
filtration cartridge to entrap dust particles, and is reported to be 
exceptionally efficient in doing so. 
The results of the tests are reported in Table IX, wherein a rating of 1 to 
10 was assigned to the observed exhaust. A rating of 1 represented an 
exhaust having essentially no observable entrained dust particles, while a 
rating of 10 was arbitrarily assigned to the Hoover bag. All tests were 
conducted with the vacuum used in the previous examples, except for the 
test of the Rainbow machine. 
TABLE IX 
______________________________________ 
Vacuum 
Cleaner Bag 
Rating Comments 
______________________________________ 
Hoover Bag 10 Quite visible cloud of dust. 
P-161 1 No visible dust. 
P-16 1 No visible dust. 
R-70 2 Traces of dust visible. 
FMB 10 Quite visible cloud of dust. 
Rainbow 4-5 Visible dust passing through 
seal on machine. 
______________________________________ 
EXAMPLE 5 
Vacuum cleaner bags fabricated from various materials, as described in 
Table IV or in Footnotes 1-6 of Table X, were tested for suitable normal 
use by vacuuming sequentially applied soils until the bag was full or 
vacuuming was otherwise impaired. Three different soils were used in these 
tests, the ASTM soil described in Table V, the SHS soil described in Table 
VII, and a soil containing 10 grams fine dust (per table VII) and 20 grams 
lint (Soil A). When the ASTM and SHS soils were used, 100 grams of the 
soil were applied in each sequential application. When Soil A was used, 
only 30 grams of the soil was applied each time. The results of these 
tests are reported below in Table X. Dust present in the exhaust was 
observed as in Example 4. 
TABLE X 
______________________________________ 
Va- Total 
cuum Amount 
Clean- No. Soil 
Test er Soil Collected, 
No. Bag Soil Applns. 
g Comments 
______________________________________ 
1 Hoov- A 36 1035 Appreciable dust 
er penetration 
throughout 
test. Bag full; 
soil loosely 
compacted. 
2 R-70 A 55 1516 Some dust pene- 
tration through 
bag was observed 
up to soil 
No. 41. Bag full. 
3 R-70 A 56 1680 Bag inlet orifice 
reinforced with 
P-16 material. 
Some dust 
observed proxi- 
mate orifice for 
first five soil 
applications. Bag 
full. 
4 P-16 A 76 2196 Very slight dust 
penetration ob- 
served, which 
continued to 
soil No. 35. Bag 
full; soil tight- 
ly compacted. 
5 P-161 SHS 25 2402 No visible dust 
observed during 
vacuuming. No 
loss in vacuum 
pickup capacity 
during test. Bag 
full; soil tightly 
compacted. 
6 Hoov- SHS 24 2266 Appreciable 
er dust visible dur- 
ing first several 
soil applica- 
tions. Bag full. 
7 Spun- SHS 2 -- Overwhelming 
bond- amount of dust 
ed.sup.1 penetrating bag. 
Test discontinu- 
ed after two 
soil appli- 
cations. 
8 Spun- SHS 1 -- Clay coating 
bond- began to delam- 
ed.sup.2 inate after first 
soil application. 
Test was 
discontinued. 
9 Melt- SHS 11 1054 Visible dust 
blown.sup.3 penetration a- 
cross inlet ori- 
fice. Loss of 
pickup capacity 
observed during 
11th soil remov- 
al. Test dis- 
continued. 
10 Melt- SHS -- -- Plies of mater- 
blown.sup.4 ial could not be 
adhesively affix- 
ed. Not tested. 
11 Creped SHS 20 1788 Little visible 
Paper.sup.5 dust penetra- 
tion. Loss of 
pickup capacity 
during 18th soil 
application. Bag 
had begun to 
delaminate. Bag 
full; soil not 
compact. 
12 FMB ASTM 8 683 Bag burst open 
and test was dis- 
continued. 
13 FMB ASTM 2 -- Side seam split 
during second 
soil application. 
14 FMB ASTM 2 -- Tremendous a- 
mount of dust 
observed pene- 
trating bag 
during first soil 
application. Side 
seam burst dur- 
ing second 
soiling. 
15 Melt- ASTM 2 -- Visibile dust 
blown.sup.6 penetration on 
first soiling, 
less on second. 
Side seam burst 
during first 
soil application. 
______________________________________ 
.sup.(1) Spunbonded polyester web from Reemey Corp. Basis weight 6 oz.; 
140 cfm/ft.sup.2. 
.sup.(2) Same vacuum bag materials as in Footnote 1 above, but coated wit 
3 oz. clay; 12 cfm/ft.sup.2. 
.sup.(3) Meltblown polypropylene web of 22 cfm/ft.sup.2 from James River 
Company and processed to electrically charge fibers. One scrim of 
lightweight spunbonded polypropylene. 
.sup.(4) Meltblown polypropylene web from James River Company that had 
been calendered to reduce air permeability to about 10 cfm/ft.sup.2. 
.sup.(5) Micro creped paper material of 15 cfm/ft.sup.2 from Pepperal 
Division of James River Company. 
.sup.(6) Meltblown polypropylene per Table IV, but thermally bonded. Bag 
fabricated with support scrim of spunbonded polypropylene. 
The Hoover bag was adequate in picking up the soil, although dust passing 
through the bag was a problem. The vacuum cleaner bags of the present 
invention were very efficient in this regard. Moreover, it was surprising 
that the P-161 and P-16 bags picked up a substantially greater amount of 
soil. This is because the soils were much more compact within the bag. 
None of the other bags tested performed adequately. In particular, bags 
made of the meltblown material were found to lack the structural integrity 
necessary for the vacuuming operation. 
EXAMPLE 6 
In order to determine if the vacuum cleaner bags of the present invention 
deleteriously affected vacuum motor performance, a P-161 bag and a Hoover 
bag were tested as in Example 2. During the test, a sound analysis of the 
motor was made using a Quest 215 sound level meter, Model Type 2-1EC. No 
difference was found in the sound analysis as between these two bags. 
EXAMPLE 7 
A further test was conducted using a P-161 vacuum cleaner bag of the 
present invention. The vacuum cleaner bag was soiled with fine dust 
(0.0023 oz. per sq. in. of primary filtering area) by vacuuming the dust 
through the intake port at a rate of 0.07 oz. per minute. The cleaner 
inlet tube was then plugged into a solenoid controlled plate which cycled 
open for 7.5 seconds and closed for 7.5 seconds. The vacuum was operated 
in this manner continuously for 12 hours. No negative effect was observed 
for either the bag or the vacuum.