Note: Descriptions are shown in the official language in which they were submitted.
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-- 1 --
IMPROVE~ENTS IM AND RELATING TO SYNT~ETIC DOWN
DESCRIPTIO~
This invention relates to synthetic down and has
particular reference to light-weight thermal
insulation systems which can be achieved by the use of
fine fibres in low density assemblies.
Vnited States Patent Specification NoO 4,588,635
describes and claims a synthetic fibre batt thermal
insulator material which comprises a blend of
(a) 80 to 95 weight percent of spun and drawn
crimped, staple synthetic polymeric microfibres
having a diameter of from 3 to 12 microns; and
(b) 5 to 20 weight percent of synthetic polymeric
staple macrofibres having a diameter of from
more than 12 up to 50 microns, said batt having
the following characteristics:
(i) a radiation parameter defined as the
intercept on the ordinate axis at zero density
of a plot of RcPF against PF less than 0.173
(W/m-K~kg/m3) [0.075(Btu-in/hr-ft2-F)(lb/ft3)1
tii) a density PF from 3. 2 to 9.6 kg/m3 (0.2 to
0.6 lb/ft ) and an apparent thermal conductivity
Rc measured by the plate to plate method
according to ASTM C518 with heat flow down of
less than 0.072 W/m-K (0.5 Btu-in/hr-ft2-F).
This material approaches, and in some cases exceeds
the thermal insulating properties of natural down.
From a mechanical standpoint, it is a matter of
experience that extremely fine fibres suffer from
deficiencies of rigidity and strength and make them
difficult to produce, manipulate and use. Recovery
properties of such a synthetic insulator material are
enhanced at larger fibre diameters, but an increase in
the large fibre component will seriously reduce the
thermal insulating properties overall.
The problems associated with mechanical stability of
fine fibre assemblies are exacerbated in the wet
condition since surface tension forces associated with
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the presence of capillary water are considerably
greater than those due to gravitational forces or
other normal use loading and and they have a much more
deleterious effect on the structure. I
According to the present invention there is provided
a synthetic fibre thermal insulator material in the
form of a cohesive fibre structure, which structure
comprises an assemblage of:
(a) from 70 to 95 weight percent of synthetic
polymeric microfibres having a diameter of from
3 to 12 microns; and
(b) from 5 to 30 weight percent of synthetic
polymeric macrofibres having a diameter of not
less than 12 microns,
characterised in that at least some of the fibres are
bonded at their contact points, the bonding being such
that the density of the resultant structure is within
the range 3 to 16 kg/m3 (0.2 to 1.0 lb/ft3), the
the bonding being effected without significant loss of
thermal insulating properties of the structure
compared with the unbonded assemblage.
-- ~ 3 ~
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The invention also includes a method of forming a
thermal insulating material which method comprises
forming a fibre assemblage
(a) from 70 to 95 percent by weight of synthetic
polymeric microfibres having a diameter of from
3 to 12 microns; and
(b) from 5 to 30 percent by weight of synthetic
polymeric macrofibres having a diameter not less
than 12 microns,
(c) shaping the assemblage so formed, and effecting
bonding between at least some of the fibres at
their contact points such that the density of
the resultant structure is within the range 3 to
16 kg/m3 (0.2 to 1.0 lb/ft3),
(d) bonding being effected without significant loss
of thermal insulating properties compared with
the unbonded assemblage.
It is preferred that the resultant fibre assemblage
has a radiation parameter defined as the intercept on
the ordinate axis at zero density of a plot of KCPF
against PF less than 0.173 (W/m-K)(kg/m3) [0.075(Btu-
in/hr-ft2-F)(lb/ft3)] and a density PF from 3.2 to
~ 3 ~
9.6 kg/m3 (0.2 to 0.6 lb/ft3) and an apparent thermal
conductivity Kc measured by the plate to plate method
according to ASTM C518 wlth a heat flow down of less
than 0.072 W/m-K ~0~5 Btu-in/hr-ft2-F).
Microfibres ancl macrofibres for use in the present
invention may be manufactured from polyester, nylon,
rayon, acetatex, acrylic, modacrylic, polyolefins,
spandex, polyaramids, polyimides, fluorocarbons,
polybenzimidazols, polyvinylalcohols,
polydiacetylenes, polyetherketones, polyimidazols and
phenylene sulphide polymers such as those
commercially available under the trade-mark RYTON.
In general it is preferred that the macrofibres are
drawn following extrusion to impart tensile modulus
of at least 63 g/dtex (70 g/den).
The bonding may be effected between at leas-t some of
the macrofibres to form a supporting structure for
the microfibres, or may be between both macrofibres
and some of the microfibres at their various contact
points.
.... . . . . .... .. ..
~3~ 8
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The macrofibres may be sel~cted from the same material
and may be either the same as the microfibres or
different.
In one aclvantageous embodiment of the invention
microfibres are formed from po:Lyethylene terephthalate
and the macrofibres are selected from polyethylene
terephthalate or a polyaramid, such for example, as
that commercially available under the Trade Mark
"Kevlar~.
The macrofibres can be monofibres, i.e. fibres having
a substantially uniform structure or may be
multi-component fibres having a moiety to facilitate
macrofibre to macrofibre bonding. The macrofibre may
be a fibre mixture in which at least 10~ by weight
comprises macrofibres of a lower melting point
thermoplastic material to assist the macrofibre to
macrofibre bonding. In a further embodiment of the
invention the macrofibres may be a fibre mixture
comprising multi-component macrofibres and a
monocomponent macrofibre capable of bonding one with
the other.
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In another embodiment of the present invention the
macro component fibre may be a mix or blend of
macrofibres having different properties for example, a
macro fibre mix may comprise two or more different
fibres such as a polyester fibre to give the desired
bonding and a "Kevlar" fibre to give stiffness. The
proportion of stiffening fibre to bonding fibre may be
varied to provide different properties subject to the
requirement that the proportion oE bondable fibres is
sufficient for the macrofibre structure to provide an
open support for the microfibres as hereinafter
described.
Some materials, such for example as polyphenylene
sulphide fibres, aromatic polyamides of the type
commercially available under the trade-maxk "APYIEL",
and polyimide fibres such as those manufactured by
Lenzing AG of Austria, exhibit flame retardant
properties or are non-flammable. Such materials can,
2~ therefore, confer improved flame or fire resistant
properties on manufactured products containing the
materials in accordance with the present invention~
Methods of manufacturing such fibres are well known,
see for example, United States Patent Specification
No. 4,148,103.
~seful two component fibres include type TJ04S2, a
side-by-side polyester/polyester material and type
TJ04C2, a sheath/core polyester/polyester material,
both available from Messrs. Teijin Ltd~, of Japan.
The bonding in the structures in accordance with the
invention is preferably, principally between the
fibres of the macrofibre component at their contact
points. The purpose of the macrofibre to macrofibre
bonding is to form a supporting structure for the
microfibre component, said supporting structure
contributing significantly to the mechanical
properties of the insulating material. By bonding the
macrofibres, in accordance with the invention the
macrofibres maintain an open bonded fibre structure
within which the microfibres can be accommodated.
Any means of bonding between the macrofibres may be
employed such, for example, as by the addition of
solid, gaseous or liquid bonding agents whether
g ,.
thermoplastic or thermosetting or by the provision of
autologous bonds in which the fibres are caused to
bond directly through the action of an intermediary
chemical or physical agent.
The method of bonding is not critical, subject only to
the requirement that the bonding should be carried out
under conditions such that the macrofibre component,
does not lose its structural integrity. It will be
appreciated by one skilled in the art that any
appreciable change in the macro- or microfibres during
bonding will affect the thermal properties adversely;
the bonding step needs, therefore, to be conducted to
maintain the physical properties and dimensions of the
fibre components and the assemblage as much as
possible.
f
The thermal insulating properties of the bonded
assemblage are preferably substantially the same as,
or not significantly less than, thermal insulating
properties of a similar unbonded assemblage.
i
In a particular embodiment of the present invention
bonding within the structure may be effected by 3
heating the assemblage of fibres for a time and at a
temperature sufficient to cause tùe fibres to bond.
:3L 3 ~
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Such heating period may be at a temperature of 125 C
(257F) to 225C (437F) for a period of the order of
1 minute to 10 minutes and preferably at a temperature
of 140 C t284 F) to 200 C (392 F) for a period of
about 3 to 7 minutes; these periods are, of course,
dependent upon the material of the macrofibre
component.
The microfibres and optionally also the macrofibres
constituting the assemblage of the invention may be
crimped to assist in the production of a low density
intimate blend or assemblage of the two components.
Crimping techniq~es are well known in the art, but the
average crimp number for both microfibres and
macrofibres is preferably within the range of 3 to 8
crimps/cm (8 to 20 crimps/inch). The presence of crimp
further assists re-establishment of loft in the fibre
assembly after compression or wetting.
In a preferred embodiment the microfibres may have a
tensile modulus of from 36 to 81 g/dtex (40 to 90
g/den). This relatively high tensile modulus
contributes to a high bending modulus in the material
of the invention and assists with the mechanical
performance of the material in accordance with the
invention.
In another embodiment of the present invention,
lubricants may be included in one or both components
of the assemblage. Typical lubricants are aqueous
solutions of organopolysiloxanes, emulsions of
poytetrafluoroethylene and non-ionic surfactants. Such
lubricants may be applied to the fibres by spray or
dip techniques well known in the art.
The assemblage of macrofibres and microfibres may be a
batt consisting of plied card-laps although other
fibrous forms such as air~laid webs are equally
suitable. Webs and batts in which some fibres are
oriented in the through-the-thickness direction as
well as in the primary sheet plane are of distinct
advantage from a mechanical performance standpoint.
Webs of continuous filaments whether spun, bonded or
otherwise produced may be used.
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In another embodiment of the invention, the assemblage
may be in the form of clusters or balls. Such clusters
can be prepared by hand or through the use of
commercially available machinery such as automatic
dicing, tumbling or ball-rolling machinery. Batts or
clusters in accordance with the invention may achieve
densities comparable to the densities of natural down,
i.e. of the order of less than 16 kg/m3 (l.0 lb/ft3)
and typically about 8 kg/m3 tO.5 1b/ft3)o
In cluster form, the insulator material of this
invention surprisingly provides extremely good
recovery from compressional loading. Furthermore,
since it is compatible with current down processing
equipment, it represents a viable synthetic down
replacement material both from a performance and a
processing standpoint.
Thermal insulating material in accordance with the
present invention in the form of clusters tends to
enjoy a more random orientation of the fibres, thus
providing greater compressional recovery and more
uniform properties. These clusters furthermore enjoy
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the advantage of being capable of being handled in
established down handling and filling machinery. Such
clusters may be made by shaping the fibre assemblage
using a "cotton ball~ rolling machine. Typical
machines suitable for this purpose are manufactured by
Bodolay/Pratt Division of the Package Machin~ery Co.,
of Florida, USA, and by Internationale
Verbandstoff-Fabrik of Switzerland.
Following is a description by way of example only of
methods of carrying the invention into effect.
In the following examples where reported the following
tests were employed:-
Density: The volume of each insulator sample was
determined by fixing two planar sample
dimensions and then measuring thickness at
0.014 kPa (0.002 lb/in2) pressure. The mass
of each sample divided by the volume thus
obtained is the basis for density values
reported herein. Thickness was measured at
0.014 kPa (0.002 lb/in2).
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Apparent thermal conductivity was measured in accord
with the plate/sample/plate method described by ASTM
Method C518.
Radiation Parameter, C was calculated from the
expression:
c F KaPF
where Kc = apparent thermal conductivity of the
. material,
PF = density of the material, and
Ka = the thermal conductivity of still air,
= 0.025 W/m-K (0.175 Btu-in/hr-ft2-F).
Compressional Strain: Strain at 34.4 kPa ~5 lb/in2),
which was the maximum strain in the compressional .-
recovery test sequence, was recorded for each test.
Compressional Recovery and Work of Compression and
Recovery:
Section 4.3.2 of Military Specification MIL-B-41826E
describes a compressional-recovery test technique for
fibrous batting that was adapted for this work, The
essential difference between the Military
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Specification method and the one employed is the lower
pressure at which initial thickness and
recovered-to-thickness were measured. The measuring
pressure in the specification is 0.07 kPa(0.01 lb/in2)
whereas 0.014 kPa (0.002 lb/in2) was used in this work.
Water Absorption Capacity: ASTM Method D1117 provided
the starting point for development of the water
absorption-capacity and absorption-time test used.
However, wetted-sample weighings were made at frequent
intervals during the first six hours of immersion and
another weighing was made after twenty-four hours
(Method D1117 requires only one wetted sample
weighing). A unique sample-holder and a repeatable
technique for draining excess water prior to each
weighing were adopted after some initial
experimentation.
Drying Time: Af-ter each absorption capacity test, f
weighings were made at one-half hour intervals as the f~
sample air-dried on a wire rack in a 21C (70F), 65% f
r.h. atmosphere. I
13~3~ ~ 3
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Batt Cohesiveness: A 5.1 cm (2 inch) thick, 14.5 cm
(5.7 inch) diameter circular test-specimen was cut
from each batt. Each specimen was gripped so that it
could be pulled apart in the direction perpendicular
to the batt plane, i.e. tensile tested in the
through-the-thickness direction. Results were recorded
in terms of tensile strain at the time of initial batt
separation and expressed as extension ratios, which
are defined as the ratio of the batt thickness at
separation or disruption to the original batt
thickness under zero applied load.
Cluster Cohesiveness: Individual clusters weighing 60
mg. and having diameters of 3.05 to 3.15 cm (1.20 to
1.25 inches) were mounted in light-weight
spring-action jaws in a tensile test machine. The jaw
faces were lined with rubber and measured 0.64 x 0.64
cm (0.25 x 0.25 inches); they were spaced to provide
an initial separation (gauge length) of 1.91 cm (0.75
inch). The maximum force attained as each cluster was
drawn apart and fully separated was recorded.
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The down used throu~hout the examples was actually a
down/feathers mixture0 80/20 by weight, per
MIL-F-43097G, Type II, Class I. This mixture is
commonly and commercially referred to as "down" and is
referred to as "down" herein.
!
COMPARATIVE_EXAMPLE 1
Consistent with UIS. Patent No. 4,588,635 a quantity
of spun and drawn 3.05 cm (1.2 inch) long microfibres
having a diameter of 7.5 microns was provided. The
fibres were lubricated with a silicone finish. The
spun-and-drawn microfibres were polyester and were F
drawn to achieve a relatively high tensile modulus
54-81 g/dtex (60-90 g/den), which contributed
significantly to a high bending modulus. After
drawing they were crimped, cut into staple, and
thoroughly opened, or separated, in a card. The
average crimp frequency was 5.5 cm (14 in), and the
average crimp amplitude was 0.l0 cm (0.0~ in). Loft
and compressional characteristics were improved
further through the blending with 10 percent by weight
of macrofibres of the same polyester (polyethylene
teraphthalate) having a diameter of 25.5 microns. The
macrofibres were lubricated with a silicone finish and
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were characterised in part by a staple length of 5.6
cm (2.2 in), an average crimp frequency of 3.4/cm
(8.5/in), and a crimp amplitude (average) of 0.15 cm
(0.06 in). The blend was carded into a batt. The
physical properties of the batt are shown in Table
below. 1-
COMPARATIVE EXAMPLE 2
The procedure of Comparative Example 1 was repeated
with the exception that the macrofibre used therein
was replaced with 20 percent by weight of uncrimped
poly(p-phenylene teraphthalamide) fibres havin~ a
diameter of 12 microns, a length of 7,6 cm (3.0 in),
and a silicone lubricant finish. The physical
characteristics of the material formed are given in
Table I below.
EXAMPLE 1
A quantity of 0.55 dtex (0.5 denier) 7.5 micron
diameter polyester microfibre that had been spun,
drawn, cut to a staple length of 3.0 cm (1.2 in) and
crimped was first opened in a wire-clothed carding
machine. The opened fibre was then sco~red, dried and
treated with a silicone finish that imparts lubricity
. 7
~3:~$~
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and water repellency. The microfibre was then
combined and uniformly blended with a 4.4 dtex, 5.1 cm
(4 denier, 2 in) long polyester binder fibre of the
side-by-side type (Type TJO4S2, available from
Teijin). Blending was achieved by subjecting the
mixed fibre stock to several passes through a carding
machine. The mixture ratio was 90/10,
microfibre/binder macrofibre, by weight. After the
mixed fibres had been uniformly blended and opened,
card laps (output webs from the carding machine) were
plied to form batts. The final processing step was
o ~
oven exposure of the batts at 160 C (320 F) for 5
minutes to obtain thermoplastic bonds between
microfibres and binder macrofibres and between binder
macrofibres. These bonds ensured that each batt was a
cohesive, non-separable fibrous assembly~
The prepared batts were evaluated in accord with the
test procedures described above and the results are
set forth in Table I below.
EXAMPLE 2
A quantity of 0.55 dtex (0.5 denier) 7.5 micron
diameter polyester microfibre that had been spun,
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drawn, cut to a staple length of 3.0 cm (1.2 in), and
crimped was first opened in a wire-clothed carding
machine. The opened fibre was then scoured, dried and
treated with a silicone finish that imparts lubricity
and water repellency. The microfibre was then
combined and uniformly blended with 4.4 dtex, 5.1 cm
(4 denier, 2 in) long, polyester binder fibre of the t
side-by-side type (Type TJ04S2, available from
Teijin)~ Blending was achieved by subjecting the
mixed fibre stock to several passes through a carding
machine. The mixture ratio was 90/10,
microfibre/binder macrofibre, by weight. After the
mixed fibres had been uniformly blended and opened,
the card lap (output of the carding machine) was
separated into clusters. These clusters were more or
less spherical in shape with an average diameter of
1.91 cm (0.75 in), and an average weight of 15 mg.
Cluster formation was achieved in the laboratory
through hand manipulation, although at least two
commercial processes for transforming carded fibres
into clusters or balls are known. The final
processing step was oven exposure of the down-like
clusters to a temperature of 160 C (320F) for 5
_
~ 3 ~ $ ~ ~ ~
21 -
minutes to obtain thermoplastic bonds between
microfibres and binder macrofibres and between binder
macrofibres. These bonds made each individual cluster
a cohesive, non-separable unit.
The prepared clusters were evaluated in accord with
the test procedures described above and the results
are set forth in Table I below.
EXAMPLE 3
A quantity of 0.55 dtex (0.5 denier) 7.5 micron
diameter polyester microfibre that had been spun,
drawn, cut to a staple length of 3.0 cm (1.2 in), and
crimped was first opened in a wire-clothed carding
machine. The opened fibre was then scoured, dried and
treated with a silicone finish that imparts lubricity
and water repellency. The microfibre ~as then
combined and uniformly blended with 4.4 dtex, 5.1 cm
(4 denier, 2 in) long, polyester binder fibre of the
side-by-side type (Type TJ04S2, available from
Teijin). Blending was achieved by subjecting the
mixed fibre stock to several passes through a carding
machine. The mixture ratio was 85/15,
microfibre/binder macrofibre by weight. After the
r
- 22 -
mixed fibres had been uniformly blended and openedl
card laps (output webs from the carding machine) were
plied to form batts. The final processing step was
oven exposure of the batts at 160C (320F) for 5
5 minutes to obtain thermoplastic bonds between
microfibres and binder macrofibres and between binder
macrofibres. These bonds ensured that each batt was a
cohesive, non-separable fibrous assembly.
10The prepared batts were evaluated in accord with the
test procedures described above and the results are
set forth in Table I below.
The insulator produced in this example was used to
15manufacture jackets, sleeping bags and quilts. All
were found to have and maintain thermal insulating
performance equivalent to or better than those using
down as the insulator.
EXAMPLE 4 ~-
-
A quantity of 0.55 dtex (0.5 denier~, 7.5 micron
diameter polyester microfibre that had been spun,
drawn, cut to a staple length of 3.0 cm ~1.2 in), and
crimped waq first opened in a wire-clothed carding
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machine. The opened fibre was then scoured, dried
and treated with a silicone finish that imparts
lubricity and water repellency. The microfibre was
then combined and uniformly blended with 4.4 dtex, 5.1
cm (4 denier, 2 in) long, polyester binder fibre of
the side~by-side type (Type TJ04S2, available from
Tei~in). Blending was achieved by subjecting the
mixed fibre stock to several passes through a carding
machine. The mixture ratio was 85/15
microfibre/binder macrofibre, by weight. After the
mixed fibres had been uniformly blended and opened,
the card lap (output of the carding machine) was
separated into clusters. These clusters were more or
less spherical in shape with an average diameter of
1.91 cm (0.75 in) and an average weight of 15 mg.
Cluster formation was achieved in laboratory through
hand manipulation, although at least two commercial
processes for transforming carded fibres into clusters
or batts are known. The final processing step was
oven exposure of the down-like clusters to a
temperature of 160C (320F) for 5 minutes to obtain
thermoplastic bonds between microfibres and
binder macrofibres and between binder
13:~$~ ~ ~
- 24 -
macrofibres. These bonds made each individual cluster
a cohesive, non-separable unit.
The prepared clusters were evaluated in accord with
the test procedures described above and the results
are set forth in Table I below.
EXAMPLE 5
A quantity of 0.55 dtex (0.5 denier), 7.5 micron
diameter polyester microfibre that had been spun,
drawn, cut to a staple length of 3.0 cm (1.2 in), and
crimped was first opened in a wire-clothed carding
machine. The opened fibre was then scoured, dried,
and treated with a silicone finish that imparts
lubricity and water repellency. The microfibre was
then combined and uniformly blended with 4.4 dtex, 5.1
- cm (4 denier, 2 in) long, polyester binder fibre of
the side by-side type (Type TJ04S2, available from
Teijin). Blending was achieved by subjecting the
mixed fibre stock to several passes through a carding
machine. After the mixed ibres had been uniformly
blended and opened, card laps (output webs from the
carding machine) were plied to form batts. The final
processing step was oven exposure of the batts at 160
~ 3 ~
- 25 -
C (320F) for 5 minutes to obtain thermoplastic bonds
between microfibres and binder macrofibres and between
binder macrofibres. These bonds ensured that each
batt was a cohesive, non-separable fibrous
assembly.
The prepared batts were evaluated in accord with the
test procedures described above and the results are
set forth in Table I below.
EXAMPLE 6
A quantity of 0.55 dtex (0.5 denier) 7.5 micron
diameter polyester microfibre that had been spun,
drawn, cut to a staple length of 3.0 cm (1.2 in), and
crimped was first opened in a wire clothed carding
machine. The opened fibre was then scoured, dried and
treated with a silicone finish that imparts lubricity
and water repellency. The microfibre was then combed
and uniformly blended with 4.4 dtex, 5.1 cm (4 denier,
2 in) long, polyester binder fibre of the
side-by-side type (Type TJ04S2, available from
Teijin~. Blending was achieved by subjecting the
mixed fibre stock to several passes through a carding
.
~ 3 ~
- ~6 -
machine. The mixture ratio was 80/20,
microfibre/binder macrofibre, by weight. After the
mixed fibres had been uniformly blended and opened,
the card lap (output of the carding machine) was
separated into clusters. These clusters were more or
less spherical in shape with an average diameter of
1.91 cm (0.75 in) and an average weight of 15 mg.
Cluster formation was achieved in the laboratory
through hand manipulation.
The final processing step was oven exposure of the
down-like clusters to a temperature of 160C (320F)
for 5 minutes to obtain thermoplastic bonds between
microfibres and binder macrofibres and between binder
macrofibres. These bonds made each individual cluster
a cohesive, non-separable unit~
The prepared clusters were evaluated in accord with
the test procedures described above and the results
are set forth in the following table:
- 27 - ~ 3~
TABLE_I
Example 1
Comparative Comparative IBatt,
Down Exa~D~le 1 Example 2 90/10)
Ap~arent therm~al
conductivity
W/m-K 0.040 0.040 0.039 0.039
(Btu-in/hr_ft2_FI (0.280)10.281)(0.271) l0.269)
Thermal cond. te~t ~- --
dens ~ ~ kg/m3 7.21 7.53 7.69 8.01
ilb/ft3) 10.45) ~0.47)10.48) 10.50)
Radiation ~arameter, C
~W/m-K)Ikg/m ) 1lO )lO.a 11.5 10.6 10.8
[ (Btu-in/hr-ft2-F)
lb/ft )llO )] 14~7)_ 15~0~ 14.6) l4~7)
3 - ___ _
Mimimum d nsit~ kg/m 3.85 4.01 4.0l 6.89
llb/ft ) 10.24) (0.25)10.25) 10.43)
Comp. ~train at
34.4 kPa ~
15 lb/in2) ~ % 95 96 92 97
CQmp. recovery from~ ~ - - -~~~~~~~~~~~~'
34,4 kPa ~ b
(5 lb/in2) ~ % 102 112 112 83
WQrk to compress to
34.4 kPa N-m 0.55 0.39 0.40 0.36
~5 lb/in2) (lb-in)14.9l) 13.49) l3~57)~3.21)
ResilienceC 0.53 0.62 0.60 0.59
. . _ ~
Wgttinq duEln~_Imm_Esion
Water ab~orption after
20 min. ~x dw)d 1.16 2.16 1.41 1.09
Density after 20 min
wetting kg/m3 7.69 8.02 8.17 8.49
~lb/ft3) ~0.48) ~0.50) ~0.51) ~0.53)
Water ab~orPtion after
6 hr ~x dw) 3.75 5.15 3.44 1.42
Den~ity after 6 hr
wettinq kg/m3 56.91 15.07 16.35 ll.86
llb/ft3J 13-55) 10~94) 11.02) 10.74)
- 28 ~ 3 ~
TABLE_I lCont/dl
Example Example Example Example Example
2 3 4 5 6
Cluster~ BattCluster3 Batt Clu~ter~
~QLLQ__~ 85/15 85/15 80/20 , 8Q/20
Ap~arent thermal
cond~ctivity
~/m-K 0.038 0.042 0.039 0.042 0.041
(Btu-in/hr-ft2-F)l0.264)(0.291)l0.268) l0.291)(0.286)
~en~5~L kg/m38.02 9.02 8.02 8.02 8.02
lb/ft3) 10.50) ~0.50) (0-50) (0-50) (0.50)
_ _
~adiation ~arameter, C
~W/m-K)(kg/m3~10 2) 10.2 13.4 10.6 13.4 12.9
[IBtu-in/hr-ft2-F)
llb/ft ~l10 )]l4~4) l5.8) l4~6) l5.8) l5~6
.
Minimum densit~
kg/m3 4.17 7.37 4.17 6.25 3.85
~lb/ft ) (0.26) ~0.46) (0.26) 10.39) ~0.24)
comP~ strain at
34,4 kPa 7 b
¦5 lblin2)~ X 95 96 95 96 95
.. _ _ .
Comp. recoverY
from 34.4 kPa) b
15 lb/in2) ~ X 130 81 135 87 132
Work to comPres~
to 34.4 kPa N-m 0.54 0.35 0 54 0~34 0.52
(5 lb/in) (lb-in) (4.75~ (3-13) (4.76) (3-~1) (4-56)
Resilience 0.44 0.58 0.43 0.61 0.46
Wet5in~ durin _Immers_on
Water absorptior
after_20 min.
(x dw)d 1.61 1.04 1.14 1.08 1.06
D~ s~ L~ D- ~LL~
kg/m3 6.89 8.17 5.13 8.02 4.49
(lb/ft3) (0,43) (0-51) (0.32) (0.50) (0.26)
.
Water absorption
a~ter 6 hr (x dw) 2.96 1.75 2.03 1.39 1.41
Density after 6 hr
wettina kglm3 14.43 15.39 10.26 10.90 6.39
(lb/ft ) (0.90) (0.96) (0.64) (0-68) (0,43)
TA~LE l lcont/dl ~ 3 ~
Example l
Comparative Comparative 8att
L~nl ~xample 1 Exa~e 2 90~10
Dryina after 24 hrs.
Water Immersion
Weight after 30 min
drvinq ~x dw) 3.88 4.83 3.29 1.27
.~
~e~
drYing lkg/m ) 83.37 15.23 14.~3 9.94
(lb/ft ) (5.20) jO.95) lO.90) (0.62)
Weiaht after 6 hr
drying ~x dw) 2.45 1.68 1.01 1.0
Densitv after 6 hr
dryinq kg/m3 51.30 6.57 7.05 7.85
(lb/ft ) l3.20) ~0.41) (0.44) l0.49)
Example Example Example Example Example
2 3 4 5 6
Clusters Batt Cluster~ Batt Clu~ters
90/10 85/15 85!15 ~ 80/20
Wei~ht after 30 min
dryinq tx dw~ 2.79 1.53 1.87 1.27 1.35
~_ _ .
Dengity after 30 min
drvinq kg/m 12.98 13.65 8.49 9.94 6.57
tlb/ft ) (0.81) l0.84) 10-53) l0.62) l0.41)
Weiaht after 6 hr
drying Ix dwj 1.92 1.0 1.0 1.0 1.0
Den~ity after 6 hr
drying kg/m 8.82 7.85 4.49 7.37 4.33
(lb/ft ) ~0.55) 10.49) l0.28) t0-46) l0.27)
a. Heat flow down: 5.23 cm 12.06 inches) ~pecimen thickne~s
b. Gauge length: 5.1 cm l2.00 inche~): den~ity at this
thickne~ was 8.02 kg/m3 (0.50 lb/ft3).
c. Resilience equals: work-of-recovery divided by work-to-
compres~ .
d. x dw:times dry weight.
~ 3 ~
- 30 -
It can be seen from the above Table I that the
insulating efficiency of each of Examples 1 through 6
of the invention, as characterised by
apparent-thermal-conductivity data and radiation
parameter values, closely approximates that of the
down/feathers mixture and of Comparative Examples
and 2. The insulating value of material produced in
accord with the invention, as exemplified by Example
2, in which the apparent thermal conductivity/density
diagrams for down/feathers and the synthetic clusters
of Example 2 are seen ~o be nearly coincident. It can
be seen from Table I that the mechanical performance
of Examples 1 through 6, as characterised by minimum
density, compressional strain, compressional recovery,
work to compress, and resilience, compares favourably
in most instances to the mechanical performance of the
down feathers mixture and Comparative Examples 1 and
~.
Differences do exist, however, among values for two
important mechanical performance indicators; those of
minimum density (loft) and compressional recovery.
The minimum density and compressional recovery values
for the batts of Examples 1, 3 and 5 indicate inferior
~ 3 ~ 8
- 31 -
performance compared to down/feathers and Comparative
Examples 1 and 2, while the compressional recovery
values for the cluster forms of Examples 2, 4 and 6
indicate significant performance improvement over
down/feathers. The minimum density (loft) values for
the cluster forms are virtually equal to those of
down/feathers and non-bonded Comparative Examples 1
and 2. This mechanical performance advantage oE the
synthetic clusters is a direct consequence of
difference in fibre orientation. An aggregation of
clusters like those of Examples 2, 4 and 6 (and as
would be employed in a typical insulator application)
constitutes a collection of fibres of random
orientation. This is in distinct contrast to the
ordered fibre orientation of the batt form. A large
fraction of the fibres that comprise each batt lie
more or less parallel to the plane of the batt,
contributing relatively little to its loftiness and
compressional elasticity. In the cluster form, the
random fibre alignment provides some fibres that are
perpendicular to, or nearly perpendicular to, the
insulator plane. These fibres are, in effect,
structural columns. They improve the loftiness of the
assembly and, through elastic bending and/or buckling,
32 -
greatly enhance the compressional recovery of the
insulator.
Further examination of Table I makes clear the
considerable improvement in performance during and
following water exposure that further distinguishes
Examples 1 through 6 in co~parison to the
down/feathers mixture. Density values for Examples
through 6 at the n6 hr. wetting", "30 min. drying",
and "5 hr~ drying" intervals in the wetting/drying
cycle are much lower than those for down/feathers,
indicating that Examples 1 through 6 retain loft while
wet and, most probably, insulating value to a far
greater degree than does down. Resistance to wetting
and resistance to loss-of~loft while wet are inherent
advantages of the fibre combination described herein.
The hydrophobic nature of polyester and the
microporous structure of the insulators are assumed to
contribute to these desirable characteristics.
Several further comparative examples were prepared for
the purpose of documenting the insulator stability and
cohesiveness that was manifest through examination and
1 3 ~ 8
- 33 -
handling of Examples 1 through 6, above. These
comparative examples were as follows:
COMPARATIVE EXAMPLE 3
_~ ?
The procedure of Example 1 was repeated to produce
another batt having a fibre mixture ratio of 90/10,
microfibre/binder macrofibre by weight. However, the
final processing step described for Example 1, oven
exposure, was omitted to provide a non-bonded batt for
comparative purposes.
COMPARATIVE EXAMPLE 4
The procedure of Example 5 was repeated to produce ;
another batt having a fibre mixture ratio of 80/20,
micro~ibre/binder macrofibre by weight. However, the
final processing step described for Example 5, oven
exposure, was omitted to provide a non-bonded batt for
comparative purposes.
COMPARATIVE EXAMPLE 5
The basic procedure of Example 4 was repeated to
produce another collection of clusters having a fibre
mixture ratio of 85/15 microfibre/binder macrofibre,
by weight, with the exception that the final oven
1 3 ~
- 34 -
exposure step was omitted. The clusters produced
differed from those of Example 4 in that their average
diameter was 3.0 cm (lo 2 in), their average weight was
60 mg, and they were not bonded.
S
An additional example of the subject inventicn was
also prepared to further facilitate documentation of
the stability and cohesiveness of insulating media
made according to the invention. This example was as
follows:
EXAMPLE 7
The basic procedure of Example 4 was repeated to
produce another collection of clusters having a fibre
mixture ratio of 85/15, microfibre/binder macrofibre
by weight. The clusters produced differed from those
of Example 4 only in size and weight. The clusters of
this example, like those of Comparative Example 5, had
an average diameter of 3.0 cm (1.2 in), and an average
weight of 60 mg. The clusters of the present example
were, however, subjected to oven exposure at 160 C
(320 F) for 5 minutes to obtain thermoplastic bonds
between microfibres and binder macrofibres and between
~ 3 ~
- 35 -
binder macrofibres.
Insulating batts of Examples l and 5 of the subject
invention and Comparative ,Examples 3 and 4 were
evaluated, the batt cohes:iveness test previously
herein described being used, and the results are set
forth in the following table.
ABLE II
Extension Ratios Measured at the Point
of Initial Batt Separation
in Through the Thickness Tensile Tests
Extension
Ratios_
Comparative Example 3;
90/lO; non-bonded 3:l
Example l;
90~lO; bonded 12:l
Comparative Example 4;
80/20; non-bonded 3:1
Example 5
80/20 bonded 16:1
~ 3 ~
- 36 -
It will be understood from the above descriptions of
the examples and comparative examples (1) that the
batts of Example 1 and Comparative Example 3 are alike
in terms of types of fibres and proportional
quantities of fibres that they contain and (2) that
they differ in that only the batt of Example 1 has 3
been subjected to oven exposure to achieve
fibre-to-fibre bonding. Similarly, the batts of
Example 5 and Comparative Example 4 are alike in basic
composition but differ in that only Example 5 contains
fibre-to-fibre bonds.
The important effect of fibre-to-fibre bonding upon
the cohesiveness of batts of the subject invention,
specifically upon that of Examples 1 and 5, is shown
by the high extension ratios ~easured at the point of
initial batt separation and set forth in Table II. The
high extension ratios of these embodiments are in
direct contrast to the low ratios measured for 3
Comparative Examples 3 and 4 (also set forth in Table
II).
_
- 37 -
In corresponding fashion, the importance of fibre-to-
fibre bonds to the cohesiveness and integrity of
individual clusters is exemplified through comparison
of the average separation force measured for clusters
of Example 7 with the average force measured for those
of Comparative Example 5, as set forth in the
following table:
TABLE III
Ten _le Force Required to Pull Apart Clusters
Average
Force
(gms)
Comparative Example 5;
85/15; non-bonded 3
Example 7; 85/15; bonded 41
The results shown above represent a surprisingly high
13.7 x increase in average cluster separation force.
~3~$~
- 38 -
EXAMPLES 8 to 13
Bonded structures were produced in the manner
described in Example 1 using a mix of macrofibres. In
each example the microfibres are a 0.55 dtex (0.5
denier) polyester fibre. The macrofibres were a blend
of a 4.4 dtex (4 denier) polyester binder fibre as
described in Example 1 with a 1.5 dtex (1.4 denier)
stiffening fibre of "Kevlar 49".
The results are set out in Table IV. The percentage
given of constituents at the head of each example
column are percent by weight;
the first figure is the percent by weight of
microfibres (polyester), the second figure is the
percent by weight of polyester macrofibre, and the
third figure is the percent by weight of "~evlar"
stiffening fibre. Thus, 80/10/10 has the composition:
0.55 dtex (0.5 denier)
polyester microfibre 80 percent by wt.
4.4 dtex (4 denier)
polyester macrofibre 10 percent by wt.
1.5 dtex (1.4 de~ier)
~Ke~lar 49~ stif~ening ~ibre 10 percent by wt~
- 39 - ~3~
TABLE_IV
Example Example Example Example Example Example
8 ~ 10 11 12 13
~att Clusters Batt Clusters Batt Clusters
~O/lP~80/1011075/15/10 ~ 5UL~L 70l2~11Q 70/~110
ApDarent ther~al
conductivity
W/m-K 0.041 -- 0.043 -- 0.044 --
(Btu-in/hr~ft2-F)~0.283) (0-2961 (0,30
Thermal cond. te~t
den~ity kg/m38.02 8.02 8.02 8.02 8.02 8.02
llb/ft ) t0-50) (0-50) ~0,50) ~0,50) 10.50)~0.50)
.
Radiation
Darameter, C
(~/m-K)Ikg/m )
~10-2) 12.5 -- 13.8 -- 14.a --
2 o
[IBtu-in/hr ft - F)
(lb/ft3)~10 2)] ~5,4) 16.0) ~6.4)
_
Minimum densitv
kg/m 6.57 4.01 7.05 4.17 6.09 3.85
(lb/ft ) (0.41) ~0.25) (0-44) (0-26) 10.38)(0.24)
,
Comp. ~train at
34.4 kPa
(5 lb/in2)~ X~96 95 95 95 95 95
CQmD. recovery
from 34.4_kPa~
(5 lb/in2~ ~ %86 125 87 120 89 117
~QLk to comDre~s
to 34.4 kPa N-m0.41 0.40 0.38 0.44 0.38 0.52
(5 lb/in )(lb-in~ (3.60) (3.57) (3.34) (3.86)(3.41) (4.56
_ _ . .__ ._
~_ilience 0.66 0.76 0.58 0.56 0.58 0.50
_ _ . _ _ _ _
a. Heat flow down: 5.23 cm (2.06 inches) specimen thickness.
b. Gauge length: 5.1 cm (2.00 inche~); den~ity at this
thicknes~ was 8.02 kg/m3 (0.50 lb/ft3).
c. Resilience equal~: work-of-recovery divided by work-to-compres~.
d. x dw: times dry-weight.
