Nonwoven thermal insulating stretch fabric and method for producing same

A nonwoven stretch fabric is provided. The fabric is produced from a web of bicomponent fibers bonded together by fusion of fibers at points of contact and thermally crimped in situ in the web. The fabric has good uniformity, good thermal insulating properties, and is produced by subjecting a fibrous web of thermally bondable, thermally crimpable bicomponent fibers to heated gas supplied continuously to the top of the web and intermittently to the bottom of the web.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a nonwoven fibrous web, typically referred 
to herein as a "fabric", which is stretchable and is particularly useful 
as thermal insulation in active sportswear, such as skiwear and snowmobile 
suits, and in outdoor work clothes. The fabric, which comprises thermally 
bondable, thermally coilable bicomponent staple fibers, has low power 
stretch which is particularly desirable for ease and comfort during wear. 
The present invention also relates to a process for producing the fabric. 
2. Description of the Prior Art 
Nonwoven thermal insulating fabrics made of thermally bondable bicomponent 
fibers are known in the art. Such fabrics are described, for example, in 
U.S. Pat. No. 4,189,338, U.S. Pat. No. 4,068,036, U.S. Pat. No. 3,589,956 
and U.K. Patent Application No. 2,096,048. However, these fabrics do not 
possess a useful amount of stretch, since there is insufficient 
springiness in the fibers between points of fiber bonding. In fact, such 
springiness is deliberately avoided, because the fibers used to produce 
such fabrics are required to have minimal latent crimp formation during 
thermal bonding to achieve the desired low density and/or good uniformity. 
Such reduction of latent crimp has been achieved by fiber stretching (U.S. 
Pat. No. 4,189,338), by fiber annealing (U.S. Pat. No. 3,589,956), by 
crimp development prior to forming the nonwoven fabric (U.S. Pat. No. 
4,068,036), and by thermal conditioning of the fibers (U.K. Patent 
Application No. 2,096,048). 
Nonwoven thermal insulating fabrics having stretch properties are also 
known. A non-woven thermal insulating stretch material called "Viwarm" is 
produced in Japan. The material is a spray-bonded, lightly needle-tacked, 
nonwoven web of a blend of one and three denier single component polyester 
fibers, the three denier fibers having sufficient crimp to provide stretch 
properties. However, the product possesses stretch having undesirably high 
power for end uses where ease and comfort is particularly desirable and 
does not have the desired high thermal insulating properties combined with 
low density desired for optimum performance characteristics. When weight 
is of primary consideration, as in such insulated articles as skiwear, 
snowmobile suits, and coats, a relatively dense, heavy product is often 
found unsatisfactory. 
Although a nonwoven product having low-density, high thermal insulating 
properties and low power, comfort stretch, i.e., a fabric which is easily 
stretched at low force and recovers to substantially the original 
dimensions after removal of the force, is desirable, such a product was 
not available prior to the present invention. 
It is, therefore, an object of the present invention to provide a nonwoven 
stretch fabric having excellent thermal insulating values, low density, 
and low power, comfort stretch suitable for use in garments. 
Another object of the present invention is to provide a nonwoven stretch 
fabric comprised of thermally bondable, thermally crimpable bicomponent 
staple fibers. 
A further object of the present invention is to provide a nonwoven stretch 
fabric having substantially uniform thickness, weight, and density. 
A still further object of the present invention is to provide a process for 
producing a highly uniform stretch fabric having excellent thermal 
insulating values, low density, and low power comfort stretch. 
SUMMARY OF THE INVENTION 
The present invention provides a substantially uniform stretch fabric 
comprising a nonwoven web of bicomponent fibers bonded together by fusion 
of fibers at points of contact and thermally crimped in situ in the web. 
The fabric has excellent thermal insulating properties, low density, and 
low power comfort stretch with uniform thickness, weight, and density. The 
desired thermal crimping can be achieved with bicomponent fibers of the 
side-by-side type or the highly eccentric sheath/core type, and thermal 
bonding can be achieved by having a portion of the surface of the fiber 
comprised of a first component having a melting point lower than that of 
the second component. 
The present invention also provides a process for producing the stretch 
fabric of the invention which comprises forming a fibrous web of thermally 
bondable, thermally crimpable bicomponent fibers, the fibers being 
substantially free of restraint to permit crimp development, and then 
subjecting the batt to heated gas supplied continuously to the top of the 
web and intermittently to the bottom of the web to cause crimping and 
bonding of the fibers.

DETAILED DESCRIPTION OF THE INVENTION 
The bicomponent fibers used in producing the fabric of the present 
invention must be thermally bondable and thermally crimpable. Thermally 
crimpable bicomponent fibers, i.e., bicomponent fibers having latent crimp 
developable by thermal treatment, may be side-by-side type composite 
fibers 11, for example, as shown in FIG. 1, or highly eccentric sheath and 
core type composite fibers 12, for example, as shown in FIG. 2. Although 
such fibers are normally round, the fiber may have other cross-sectional 
configurations, such as elliptical, trilobal, or even rectangular, such as 
are obtained from fibrillated film. The term "bicomponent fiber", as used 
herein, is meant to include multicomponent fibers, i.e., those fibers 
having two or more components. The components of the fibers must have 
sufficient difference in thermal stress development that when the 
bicomponent fiber is subjected to thermal treatment, the fibers develop 
three-dimensional coil-like crimps. For example, the components may be a 
lower melting temperature component and a higher melting temperature 
component. 
The fibers should preferably develop an average crimp of from about 10 
crimps/cm to about 100 crimps/cm, more preferably 20 to 50 crimps/cm on 
thermal treatment as individual fibers, for example when heated to a 
temperature of about 3.degree. C. to 10.degree. C. above the melting point 
temperature of the lower melting component of the fiber in an unrestrained 
state. The crimp formed, which may be nonuniform along the length of the 
fiber is of the three-dimensional coil-type with the diameter of the coil 
preferably in the range of from about 4-20 fiber diameters or more. 
The fibers useful in the present invention must also be thermally bondable. 
At least a portion of the outer surface of the fiber must be comprised of 
a first component 13 having a melting point lower than the second 
component 14. The greater the portion of the outer surface comprised of 
the lower melting component 13, the greater the potential for bonding 
between fibers during thermal treatment. The lower melting component 13 
preferably comprises at least 50% of the outer surface of the fiber as 
shown in FIG. 1. More preferably, the lower melting component 13 
completely surrounds the higher melting component 14, as in the highly 
eccentric sheath/core type fiber shown in FIG. 2. The polymer melt 
temperature of the lower melting component 13 should be at least 
10.degree. C., preferably 20.degree. C., more preferably 30.degree. C. or 
more, below the polymer melt temperature of the second component 14 to 
facilitate processing during thermal crimping and bonding. A greater 
difference in polymer melt temperature between the components permits a 
broader range of process temperatures to be utilized. 
The lower melting component of the bicomponent fiber may be selected from 
thermoplastic bondable polymers, such as polyolefins, polyamides and 
copolyamides, polyesters and copolyesters, acrylics, and the like. The 
higher melting component of the bicomponent fiber may be selected from 
fiber-forming polymers, such as polyolefins, polyamides, polyesters, 
acrylics, and the like. The fiber components are selected such that the 
thermally induced changes in dimension to achieve the previously stated 
crimping and polymer melting temperature differentials are satisfied. An 
excellent bicomponent fiber for use in the present invention is a fiber 
having polyethylene as the low melting component 13 and polypropylene as 
the high melting component 14 in the cross-sectional configuration shown 
in FIG. 2. Such fiber is available from Chisso Corp., Japan. 
The bicomponent fibers may also be blended with conventional staple fibers, 
with microfibers, or with other bicomponent fibers. However, the thermally 
crimpable, thermally bondable bicomponent fibers must be present in 
sufficient amount to achieve the necessary thermal bonding and desired 
stretch characteristics. Generally, thermally bondable, thermally 
crimpable bicomponent fibers should comprise at least 50% by weight, 
preferably at least 75% by weight, of the fibers of the fabric to obtain 
desired bonding and stretch. The fabric may contain 100% bicomponent 
fibers. 
Normally, the bicomponent fibers useful in the fabric of the present 
invention may have a denier within a wide range, for example, from at 
least as wide as 0.5 to 50 denier. When the fabric is to be used in 
apparel where fabric properties such as softness and drapeability are 
desirable, fibers of finer denier, for example, 0.5 to 5 denier, are 
generally preferred. 
The bicomponent fibers useful for the fabric of the present invention may 
be in the form of staple fibers, continuous filament or tow. The fibers 
are preferably staple fibers, more preferably fibers of about 1.5 to 5 cm 
in length. Generally, the nonwoven fabric is produced from a carded or 
air-laid web which requires the use of staple fibers. Also, staple fibers 
are less restricted in such a web and have greater potential for 
development of latent crimp during thermal processing. 
The fabric of the invention is generally about 0.4 to 2.0 cm in thickness 
depending on end use requirements, such as the desired degree of thermal 
insulation. The fabric may be even thicker where very high thermal 
insulation is required. The fabric thickness is measured as follows: 
A 10.2 cm.times.15.2 cm die cut sample is subjected to a compressive force 
of 413.6 Pa for 30 seconds, allowed to recover for 30 seconds with the 
force removed, subjected to a compressive force of 87.1 Pa for 30 seconds, 
allowed to recover for 30 seconds with the force removed, and then 
measured for thickness after being subjected to a compressive force of 
14.5 Pa for 30 seconds and while under such force. 
The fabric weight is generally in the range of about 40 to 300 g/m.sup.2. 
It is usually desirable that the bulk density of the fabric be kept 
relatively low so as to provide high thermal insulating properties while 
keeping the fabric weight low. Fabric density in the range of from about 
0.005 to 0.025 g/cm.sup.3 is preferable for most apparel applications. 
The fabric of the present invention preferably possesses a low power, 
comfort stretch with the force necessary to stretch the fabric 50% less 
than about 900 g, more preferably about 350 g to 800 g. The force to 
stretch is measured as follows: 
A 10.2 cm.times.15.2 cm die cut sample, mounted in 3.8 cm wide jaws of a 
testing instrument such as an "Instron" tensile tester that are spaced 
apart a distance of 12.7 cm, is stressed to a length of 19.1 cm (50% 
extension), a total of 10 times. The rate of extension is 50.8 cm per 
minute. The force required for extension and the increase in specimen 
length for each extension is measured and recorded. The specimen length is 
also recorded after a 24 hour rest period. 
The thermal insulating property of the fabric of the present invention is 
preferably at least about 7K.m.sup.2 /watt/cm, more preferably at least 
about 8K.m.sup.2 /watt/cm. Where fabric weight is an important 
consideration, for example, in apparel, the thermal insulating property 
per unit of fabric weight is preferably at least about 0.04K.m.sup.2 
/watt/g/m.sup.2. To determine the thermal insulating property a sample is 
tested on a guarded hot plate in the manner described in ASTM D 1518-64 
with the sample subjected to a force of 14.5 Pa during the test. 
The preferred process for producing the nonwoven thermal insulating stretch 
fabric of the invention comprises forming a fibrous web of thermally 
bondable, thermally crimpable bicomponent fibers and then subjecting the 
web to heated gas supplied continuously to the top of the web and 
intermittently to the bottom of the web to cause crimping and bonding of 
the fibers. This process may be carried out using the apparatus shown in 
FIG. 4. 
A fibrous web 31 may be formed by any known method, for example, carding, 
airlaying through use of apparatus such as a "Rando-Webber", or tow 
spreading. The fibrous web may be formed of staple fibers or continuous 
filament fibers. The fibrous web 31 is then fed into oven 32 where it is 
conveyed by porous conveyor means 33 which must be sufficiently porous to 
permit flow of heated gas therethrough. A useful conveyor means is 
galvanized window screen. The fibrous web should be fed into oven 32 with 
sufficient overfeed to permit the fibers in the web to coil during crimp 
development. Generally, the overfeed may be in the range of from about 30% 
to 100%, preferably about 50%. 
The fibrous web 31 is passed through a preheat oven portion where the web 
is subjected to hot air directed from top plenum 34 and bottom plenums 35 
and 36. The distance between the lower surface of top plenum 34 and 
conveyor means 33 is dependent upon the height to which the fibrous web 31 
is raised by the hot air from the bottom plenums and the pressure of the 
air directed from the top plenum. Sufficient clearance is provided so that 
movement of the fibrous web by the conveyor is not hindered by contact 
with the top plenum. However, the top plenum should be sufficiently close 
to the fibrous web to provide an effective amount of hot air to cause 
crimp development and thermal bonding. The temperature of the hot air 
directed from top plenum 34 and bottom plenums 35 and 36 should be higher 
than the melting temperature of the low melting constituent of the 
bicomponent fiber and lower than the melting temperature of the high 
melting constituent of the fiber. The temperature of the hot air used 
throughout oven 32 may be the same. 
The fibrous web is then carried through a portion of the oven where hot air 
is provided only from top plenum 34. Then, the fibrous web is subjected to 
hot air provided from both top plenum 34 and bottom plenum 37. The force 
of the hot air provided by bottom plenum 37 is sufficient to raise the 
fibrous web 31 from the conveyor such that the web is unrestrained and the 
fibers of the web are free to develop the inherent latent crimp. The low 
melting constituent of the fiber is also softening at this time to permit 
bonding between the fibers. The fibrous web again passes through a portion 
of the oven where it is conveyed by conveyor means 33 with hot air 
provided only by upper plenum 34. Then, the fibrous web is again subjected 
to hot air from both top plenum 34 and bottom plenum 38, with the force of 
the air provided by bottom plenum 38 sufficient to again raise the web 
from the surface of conveyor means 33 such that the web is unrestrained 
and the fibers are permitted to freely crimp. 
The fibrous web 31 can then again be passed through a portion of the oven 
where it is conveyed by conveyor means 33 with hot air provided only by 
upper plenum 34 and then again through a portion where hot air is provided 
from both top plenum 34 and bottom plenum 39 with the force of the air 
provided by bottom plenum 39 sufficient to raise the web from the surface 
of conveyor means 33. The number of cycles of heating, in which the hot 
air is provided only from the top plenum and then from both the top and 
bottom plenums, can vary depending on such factors as, for example, 
conveyor speed, web density, and thickness. The web may then pass through 
a portion 42 of the oven where it is conveyed by conveyor means 33 with 
hot air provided by only the top plenum to effect further fiber bonding. 
The web, in which the fibers have sufficiently developed crimp and the 
lower melting constituent has softened sufficiently to permit bonding, is 
then conveyed through cooling portion 40 where bonds between the fibers 
develop. The cooled stretch fabric 41 of thermally bonded, crimped fiber 
is then typically wound into a storage roll. 
An unbonded fibrous web 51 of bicomponent fibers 52 prior to thermal 
treatment is shown in FIG. 5. After thermal treatment, as shown in FIG. 6, 
the bonded fibrous web 61 of thermally crimped, thermally bonded 
bicomponent fibers 62 shows a marked increase in thickness. The thickness 
of the fabric may more than double during thermal treatment. In FIG. 3, a 
greatly enlarged view of a portion of the bonded web shown in FIG. 6, 
bonded contact points 23 between fibers 22 of web 21 are more clearly 
visible. 
It is believed that the combination of thermal crimping and thermal bonding 
of the fibers in the fabric produced during thermal treatment contribute 
to producing the desired stretch characteristics of the fabric. Generally, 
both the amount of crimp developed and the degree of interfiber bonding 
increase as the thermal treatment temperature increases above the melting 
point temperature of the lower melting point temperature component. If the 
thermal treatment temperature is too low, insufficient crimping and 
bonding will occur. If the thermal treatment temperature is too high, 
excessive thermal bonding and thermal crimping will occur, resulting in a 
fabric requiring a relatively high degree of force to stretch. Generally, 
an indicated treatment temperature from about 3.degree. C. to 10.degree. 
C., more preferably 4.degree. C. to 6.degree. C., above the melting point 
temperature of the lower melting point temperature fiber component will 
produce the desired balance of stretch properties desired for use in 
apparel. 
It is further believed that the excellent uniformity of the fabric of the 
present invention is achieved by the use of the alternating restricted and 
unrestricted condition which occurs as the fiber web is intermittently 
subjected to heated air from below the web. The fiber web is restricted 
from shrinking while on the conveyor. The fiber web is substantially 
unrestricted when it is raised above the conveyor by the force of the air 
stream directed from the lower plenum. 
Crosslapping of the fiber web either before or after the thermal treatment 
may also be carried out. The fiber web may be crosslapped prior to the 
thermal treatment to increase the thickness and/or width of the fiber web 
and to provide a bias structure to the fiber web. This has been found to 
be particularly useful where the fibrous web has been formed by carding. 
The thermal treatment is carried out in the same manner as for a 
non-crosslapped fibrous web. The fibrous web may also be crosslapped 
subsequent to the thermal treatment to provide increased thickness and/or 
width of the final fabric and to provide a bias structure to the fabric. 
After crosslapping, the fibrous web is subjected to thermal treatment to 
bond the crosslapped layers together. Usually, little thermal shrinkage of 
the fibers and web occurs during this second thermal treatment since the 
crosslapped web is generally in an essentially restricted condition on a 
conveyor. The temperature at which the crosslapped layers are bonded 
should be high enough to cause bonding, but not so high as to 
substantially affect the stretch properties of the fabric. 
The invention will be further illustrated by the following examples: 
EXAMPLE 1 
An air-laid fibrous web is formed from opened bicomponent 
polyethylene/polypropylene fibers ("Chisso" ES fibers, available from 
Chisso Corp., Osaka, Japan) of 1.5 denier per filament and 38 mm cut 
length in the conventional manner. The web is conveyed, at 370 cm per 
minute, by a wood slat conveyor to an oven, similar to that shown in FIG. 
4, having a galvanized window screen oven conveyor whose velocity is 240 
cm per minute. The web formed a sinusoidal shape on the screen conveyor 
and was conveyed into an air-heated oven whose indicated air temperature 
was 138.9.degree. C. Air was directed from both above from a top plenum 
and below from bottom plenum chambers 35 and 36 onto the fibrous web. The 
air plenum chambers in both the bottom and top portions of the oven were 
constructed of a thin flat steel plate having 0.318 cm diameter circular 
holes staggered on 1.25 cm centers. After a traveling distance of about 66 
cm in the oven, the web was gently raised to a height of about 5 to 8 cm 
above the screen by the force of the hot air from beneath the web provided 
by plenum chamber 37. After traveling a distance of about 23 cm, the force 
of the air from beneath was reduced and the web was returned to the 
conveyor for a distance of about 13 cm. This process was repeated two more 
times with the web being raised by the hot air provided by plenum chambers 
38 and 39 as the conveyor moved through the oven. The web was then 
conveyed by the screen through the oven for a distance of about 280 cm 
and then emerged from the oven. The web remained on the screen for a 
distance of about 100 cm to allow cooling. The resulting fabric was then 
removed from the screen and wound with slight tension onto a take-up tube. 
The thermal bonded fabric was extremely uniform in width, thickness, and 
density and had increased basis weight, thickness, and bulk density as is 
illustrated by the following data (Table 1). 
TABLE 1 
______________________________________ 
Mean Standard Coefficient of 
Value Deviation variation % 
______________________________________ 
Unbonded batt 
Weight (g/m.sup.2) 
26.9 0.52 1.9 
Thickness (cm) 
0.42 0.01 2.5 
Bulk density (g/cm.sup.3) 
0.0065 0.00017 2.6 
Thermally bonded fabric 
Weight (g/m.sup.2) 
77.8 2.55 3.3 
Thickness (cm) 
0.67 0.015 2.2 
Bulk density (g/cm.sup.3) 
0.0116 0.0003 2.9 
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EXAMPLES 2-10 
Examples 2 through 10 were processed in the following manner with the 
specific process conditions, fiber compositions, and web weights detailed 
in Table 2 which follows. The bicomponent fibers used were "Chisso ES" 
fibers, 38 mm in length, with denier as indicated in Table 2, and the 
polyester fibers used were 1.75 denier, 38 mm staple fibers. 
An air-laid fibrous web, formed in the conventional air-laid manner from 
the fiber compositions set forth in Table 2, is conveyed, at 450 cm per 
minute, by a wood slat conveyor to a galvanized window screen oven 
conveyor, whose velocity is 300 cm per minute. The web formed a sinusoidal 
shape on the screen conveyor and was conveyed into a heated air oven. The 
indicated temperature of the heated air and the plenum pressure for each 
example is set forth in Table 2. Air was directed from both above and 
below into the fiber web. After traveling a distance of about 150 cm into 
the oven, the web was gently raised to a height of about 7.5 to 10 cm 
above the screen by the force of the air beneath the web. After traveling 
a distance of about 25 cm, the force of the air was reduced and the web 
returned to the conveyor for a distance of about 7.5 cm; the force of the 
air was then increased beneath the web and the web gently rose to a height 
of about 2.5 to 5 cm above the conveyor and traveled for a distance of 
about 20 cm; the force of the air was then reduced and the web returned to 
the conveyor for a distance of about 12 cm and again the force of the air 
was increased and the web gently rose to a modest height above the 
conveyor where it traveled for a distance of about 20 cm; once again it 
was returned to the conveyor and was conveyed through the oven for a 
distance of about 280 cm and then emerged from the oven. The web remained 
on the conveying screen for a distance of about 100 cm to allow cooling. 
It was then removed from the screen and wound with slight tension and 
compression onto a paper tube. 
These examples demonstrate the effect of varying the properties of the 
input unbonded web and the process conditions. The properties of the 
resulting fabrics are set forth in Table 3. 
The examples demonstrate the excellent thermal insulating properties and 
stretch characteristics of the fabric of the invention. In Examples 2, 3 
and 4, similar unbonded webs were passed through the oven with the plenum 
pressure the same for each example, but with varying process temperatures. 
The resulting fabrics, as shown by the data in Table 3, increase in basis 
weight, thickness, force required to stretch and thermal resistance with 
increased processing temperature. Examples 5 and 6 demonstrate the effect 
of using a higher basis weight unbonded web than in Examples 2, 3 and 4 at 
different processing temperatures. The higher oven temperature resulted in 
a bonded web which reguired more force to stretch. Examples 7 and 8 
demonstrate the effect of combining conventional polyester staple fibers 
with bicomponent fibers. Although the basis weight and bulk density did 
not increase during processing of the web through the oven as much as when 
only bicomponent fibers were used, an increase in thickness was observed 
and the bonded webs had excellent thermal insulating properties and low 
force to stretch. Example 9 illustrates the effect of using a finer denier 
bicomponent fiber to form the web. Although a low oven temperature and low 
plenum pressure were used, the resulting fabric required more force to 
stretch than when a similar unbonded web of heavier denier fiber was 
processed at the same temperature using higher plenum pressure (Example 
2). Example 10 further demonstrates that lower oven temperature results in 
a bonded web requiring low force to stretch. 
TABLE 2 
__________________________________________________________________________ 
Example 
2 3 4 5 6 7 8 9 10 
__________________________________________________________________________ 
Unbonded Web Properties 
Fiber content (%) 
Bicomponent 100 100 100 100 100 75 87 100 100 
Polyester 0 0 0 0 0 25 13 0 0 
Mean fiber density 
0.915 
0.915 
0.915 
0.915 
0.915 
1.031 
0.975 
0.915 
0.915 
Fiber denier 
Bicomponent 1.5 1.5 1.5 1.5 1.5 1.5 1.5 0.9 1.5 
Polyester -- -- -- -- -- 1.75 
1.75 
-- -- 
Basis weight (g/m.sup.2) 
26.7 
23.7 
24.3 
38.8 
34.5 
33.6 
31.8 
29.6 
29.1 
Thickness (cm) 
0.22 
0.22 
0.24 
0.32 
0.30 
0.42 
0.43 
0.32 
0.29 
Bulk density (g/cm.sup.3) 
0.012 
0.011 
0.010 
0.012 
0.011 
0.008 
0.007 
0.009 
0.009 
Packing factor 
0.013 
0.012 
0.011 
0.013 
0.013 
0.008 
0.008 
0.010 
0.010 
Process Conditions 
Temperature (.degree.C.) 
135.0 
136.1 
137.2 
135.0 
137.2 
137.2 
137.2 
135.0 
133.9 
Top plenum pressure 
0.13 
0.13 
0.13 
0.13 
0.13 
0.13 
0.13 
0.13 
0.13 
(cm water) 
Bottom plenum pressure 
(cm water) 
Chamber 35 0.13 
0.13 
0.13 
0.15 
0.15 
0.08 
0.08 
0.08 
0.13 
Chamber 36 0.05 
0.05 
0.05 
0.08 
0.08 
0.03 
0.03 
0.03 
0.05 
Chamber 37 0.18 
0.18 
0.18 
0.23 
0.23 
0.17 
0.17 
0.17 
0.18 
Chamber 38 0.22 
0.22 
0.22 
0.22 
0.28 
0.19 
0.19 
0.19 
0.22 
Chamber 39 0.05 
0.05 
0.05 
0.05 
0.10 
0.05 
0.05 
0.05 
0.05 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
Example 
2 3 4 5 6 7 8 9 10 
__________________________________________________________________________ 
Bonded Web Properties 
Basis weight (g/m.sup.2) 
87.8 
98.5 
104.4 
129.8 
129.8 
75.0 
69.7 
80.0 
87.2 
Thickness (cm) 
0.46 
0.50 
0.55 
0.73 
0.68 
0.86 
0.97 
0.47 
0.48 
Bulk density (g/cm.sup.3) 
0.019 
0.020 
0.019 
0.018 
0.019 
0.009 
0.007 
0.017 
0.018 
Packing factor 
0.021 
0.022 
0.021 
0.020 
0.021 
0.008 
0.007 
0.019 
0.020 
Force to stretch 50% 
Cycle 1 (g) 205 401 723 140 512 677 418 697 118 
Cycle 10 (g) 162 314 544 115 406 517 324 493 89 
Growth in length 
Cycle 4 (%) 14 14 14 13 13 13 13 14 13 
Cycle 10 (%) 16 16 18 16 15 17 17 17 15 
24 hr. rest (%) 
5 5 5 3 5 5 5 4 2 
Thermal Resistance 
K .multidot. m.sup.2 /watt 
4.64 
5.52 
5.63 
7.59 
6.92 
8.77 
8.06 
4.65 
5.48 
K .multidot. m.sup.2 /watt per cm thickness 
9.11 
10.41 
9.39 
9.37 
9.67 
10.20 
8.31 
9.89 
9.79 
K .multidot. m.sup.2 /watt per basis weight 
0.048 
0.053 
0.050 
0.063 
0.057 
0.117 
0.116 
0.058 
0.063 
__________________________________________________________________________