BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to a process to impart permanence to a shaped non thermoplastic
fibrous material comprising amino groups. It also relates to permanently shaped fibrous
material obtainable from that process.
Description of the Related Art
[0002] Many textile processes involve the twisting of multi-filament fiber prior to subsequent
manufacturing into woven, knitted or braided structures. Twisting is the process of
combining filaments into yarn by arranging them according to a helix pattern or combining
two or more parallel single yarns into plied yarns or cords. Twist is generally expressed
as the number of turns around the longitudinal axis of the fiber per unit length of
the fiber; i.e. turns per meter abbreviated as tpm. Multi-filament yarn twisting is
generally considered as a processing aid providing high cohesion to the yarn. It is
also considered as a suitable filament arrangement for an optimum load sharing. Twisting
is also used to impart to the yarn surface a uniform morphology allowing for a better
anchoring of the matrix, such as a rubber, which in turn contributes to a more efficient
stress transfer and a better mechanical adhesion between the matrix and the reinforcing
fiber. Therefore twisting is generally employed to increase strength, smoothness and
uniformity or to obtain specific effects in the yarn.
[0003] For these reasons, it may be interesting to provide fibers stabilized in a particular
shape, for instance under a twisted form.
US 5, 794, 428 discloses a process to permanently set the twist of a thermoplastic fiber.
[0004] However, high-modulus, high-strength non thermoplastic fibrous material, and more
generally crystalline fibers, such as aramid fibers, are difficult to stabilize at
moderate and high twist levels because they have a natural tendency to untwist readily.
[0005] For low and medium twist levels, it is known to use the so-called S and Z twist arrangement,
which is a two step process combining a S twisted yarn with a Z twisted yarn leading
to a stabilized combined assembly. Nonetheless, in the case of non thermoplastic fibers
comprising amino groups, for high tpm exceeding for example a hundred turns per meter
for a 1670 dtex yarn, it is not practical, productivity and uniformity wise, to use
that process.
[0006] Now, it has been found that by submitting a shaped fibrous material to a constant
and uniformly distributed electromagnetic field generated by a specific microwave,
it was possible to impart permanence to said shaped fibrous material, even though
this material is a high modulus or a high strength non thermoplastic material comprising
amino groups.
[0007] Microwave heating is a well known technology with industrial as well as domestic
applications.
US 5, 175, 239 and
US 5, 146, 058 disclose the use of a microwave to heat treat para-aramid fibers in order to obtain
fibers showing internal cracks through the filament cross-section.
SUMMARY OF THE INVENTION
[0008] One aspect of the invention is a process of imparting permanence to a shaped fibrous
non thermoplastic material comprising amino groups comprising submitting said shaped
non thermoplastic fibrous material under low tension to a constant and uniformly distributed
electromagnetic field generated by a single mode Transverse Magnetic 010 mode cylindrical
resonant cavity microwave reactor, the rate of increase in temperature of the material
being less than 300°C/s.
[0009] A preferred embodiment of the invention is a process to impart permanence to a twisted
para-aramid fiber comprising submitting said fiber, under a tension of less than 0.2
gpd, to a constant and uniformly distributed electromagnetic field produced by a single
mode Transverse Magnetic 010 mode cylindrical resonant cavity microwave reactor,
- the uniformly distributed electromagnetic field being operated at frequencies of from
5 MHz to 500 GHz,
- the fiber being processed through the microwave reactor at a rate of from 0.01 to
1200 m/min,
- the rate of the increase in temperature of the fiber being less than 300°C/s,
- the fiber comprising at least 0.05 weight % of an aqueous composition.
[0010] A permanent shape for a non thermoplastic fibrous material may be required for special
applications such as imparting to a fiber a stretch factor independant from the elastomeric
nature of the fiber. For instance, such a permanently shaped fiber may be used in
a rubber composite in order to decrease the elongation gradient between the fiber
and the rubber.
[0011] With the process of the invention, it is possible to impart to a non thermoplastic
fiber a permanent twist of up to the maximum operational twist level. The maximum
operational twist level is generally considered as a twist level which will not provoque
fracture or rupture of the filaments composing the twist assembly. For instance, this
permanent twist level can reach 1000 tpm for a 1670 dtex yarn made of para-aramid
fiber. The fiber shows no internal crack such as the one which could appear through
the filament cross-section like described in US 5, 175, 239. It has a high cohesion
and a high stability. In particular, with the process of the invention, it is possible
to stabilize in a highly uniform manner a twisted non thermoplastic fiber. This high
stabilization may be operated for any twist level necessary for any subsequent processing
such as spiraling, knitting, weaving, braiding, felting or embedding in an elastomer
matrix or a composite matrix.
[0012] Such a permanently twisted non thermoplastic fiber may be used as a sewing thread,
a fiber to reinforce various matrixes or a woven or knitted fabric, making it possible
to achieve high cohesion and stability in a woven or knitted structure. The woven
or knitted structure made of a permanently twisted non thermoplastic fiber of the
invention is highly stable dimensionally and will not present residual torque effect.
Such a structure is also stretchable.
[0013] The process of the invention also has the advantage of eliminating intermediate steps
which would be necessary to processes of the prior art to maintain the shape of a
fibrous material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
Fig. 1 is a schematic diagram of a process according to the present invention where
the fibrous material is a fiber
Fig. 2 is a drawing showing a perspective view of the microwave reactor with a linear
trajectory for the fiber path.
Fig. 2a is a drawing showing the constant and uniformly distributed electromagnetic
field generated by a microwave reactor according to Fig.2
Fig. 3 is a drawing showing a perspective view of the microwave reactor with a sinusoïdal
trajectory for the fiber path.
Fig. 4 is a scanning electron microscopy picture of a cross section of a bundle of
filaments of Example 1 of the present application.
Fig. 4a is the related close-up of a single filament of Fig. 4.
Fig. 5 is a scanning electron microscopy picture of a cross section of a bundle of
filaments of Example 2 of the present application.
Fig. 5a is the related close-up of a single filament of Fig. 5.
Fig. 6 is a scanning electron microscopy picture of a cross section of a bundle of
filaments of Example 3 of the present application.
Fig. 6a is the related close-up of a single filament of Fig. 6.
Fig. 7 is a scanning electron microscopy picture of a cross section of a bundle of
filaments of Example 4 of the present application.
Fig. 7a is the related close-up of a single filament of Fig. 7.
Fig. 8 is a scanning electron microscopy picture of a cross section of a bundle of
filaments of Example 5 of the present application.
Fig. 8a is the related close-up of a single filament of Fig. 8.
DETAILED DESCRIPTION OF THE DRAWINGS
[0015] Referring to FIG.1, fiber 11 from supply tension regulated roll 12 is fed over rolling
guide 13 to assure the desired alignment of the fiber. The fiber is fed to the pretreatment
unit 14 where it can be watered so that the amount of water content in the fiber is
at least 0.05 weight %. The water pretreatment can be optional in the case of a never-dried
fiber having already more than 0.05 weight % water. The pretreatment unit 14 can alternatively
be a dewatering unit to tailor the amount of water contained in the supply fiber 11.
It can also be a temperature adjusting pretreatment and/or a coating or plasma or
any suitable treatment. Optionally, the pretreatment unit can be a twisting unit or
any texturizing unit imparting a filament deformation. From the pretreatment unit
14, the fiber is fed to tension-control roll 15 and then passes into the microwave
resonant cavity reactor 16. The process can be tailored to include several resonant
cavity reactors in any suitable arrangement in series or in parallel. The microwave
electromagnetic field is controlled through the microwave control 17. The fiber is
maintained in the cavity at a relatively low tension, preferably suitable to maintain
the shape of the fibrous material, preferably less than 0.2 g/denier. At the exit
of the microwave, the fiber is fed to a tension-control roll 18 and then to a guide
19. The fiber is then fed to rolling guide 20 to assure the desired alignment of the
fiber. The fiber is fed to the post-treatment unit 21 where it can be further heated,
dried or surface treated by coating or plasma treatment for instance or by any other
suitable post treatment. The use of the post-treatment unit is optional. The fiber
then passes through a rolling-tension guide 22. Finally, the fiber is wound using
a tension controlled precision winder 23.
[0016] The process of Fig. 1 can be further modified to allow the treatment of several fibers
run in parallel.
[0017] Referring now to FIG. 2, a cylindrical microwave resonant cavity reactor indicated
generally as 30 suitable for use in the present invention is depicted. The reactor
comprises a cavity defined by a cylinder 31 designed to support a TM010 (Transverse
Magnetic 010) mode and the desired resonant condition at the center frequency which
is generally set for industrial applications at 915 MHz or 2450 MHz. Suitable dimension
for a 915 MHz resonant condition are provided on Fig. 2. Typical units are 915 MHz,
400 W amplifier coupled to a 28 VDC, 53 A switching power supply or 915 MHz, 800 W
amplifier coupled to a 28 VDC, 107 A power supply.
[0018] The circular cross section reactor combines the radially symmetric electromagnetic
field distributions and the well defined axial electromagnetic field profile. By "circular
cross section" is meant herein a circular or an oval cross section.
[0019] A microwave source 32 initiates the microwave. The fiber 11 is fed through inlet
port 33 and exits through outlet port 34. The fiber path is linear.
[0020] Referring to FIG. 3, a cylindrical microwave resonant cavity reactor 40 is depicted,
similar to the one shown in FIG. 2 but comprising in addition ceramic guides 41 allowing
the fiber path to be sinusoïdal.
DETAILED DESCRIPTION
[0021] "Fibrous material", as used herein, includes endless fibers such as filaments, short
fibrous structures, short cut fibers, microfibers, multifilaments, cords, yarns, fibers,
felt, fabric, woven, knitted, braided, spiraled, felted structures or nonwoven forms.
The fibers may be made into yarns of short fibrous structures which are spun into
staple fibers, into yarns of endless fibers or into stretchbroken yarns which can
be described as intermediate yarns between staple and continuous yarns. The yarn,
fiber, fabric, woven, knitted, braided, spiraled, felted structure or nonwoven form
may be made of continuous filaments, short fibers or pulp.
[0022] "Shaped fibrous material" as used herein, includes any fiber, fabric, textile, garment,
fibrous structure or finished product made of the fibrous material as defined above,
having been submitted to any shaping process such as twisting, weaving, braiding,
crimping, plying, knitting, spiraling, felting, unidirectionally laying down or any
other deformation.
[0023] "Aqueous composition", as used herein, includes water, solvents, and/or mixture thereof
under the form of a solution, an emulsion or a dispersion. It can contain salts, polymers,
or other emulsified, dispersed or dissolved chemical compounds. Preferably, the aqueous
composition is water. This aqueous composition may be present within the fibrous material
under the free form and/or under the bound form. In a preferred embodiment of the
invention, the aqueous composition is present under both forms, free and bound.
[0024] "Thermoplastic material", as used herein, means a material that softens when exposed
to heat and returns to its original condition when cooled to room temperature. A non
thermoplastic material does not soften when exposed to heat.
[0025] The non thermoplastic fibrous material suitable in the present invention includes
any natural or man made non thermoplastic fibrous material comprising at least one
polymeric structure comprising amino groups. "Amino groups", as used herein, includes
amine groups, amide groups and/or amino-acid groups. Man made and natural fibrous
material include polyamides, polyamines, polyimides such as polybenzimidazole (PBI),
polyphenylenebenzobisoxazole (PBO), natural silk, spider silk, hair and all natural
fibers presenting amino-acid sequences. These groups can be part of a linear or branched,
cyclic or heterocyclic, saturated or unsaturated, aliphatic or aromatic chemical structure.
Preferred polymeric structures comprising amino groups include polyamides, polyamines,
polyimides, aramids, blends and mixtures thereof. Preferably, the polymeric structure
comprising amino groups is an aramid.
[0026] Aramids are polymers that are partially, preponderantly or exclusively composed of
aromatic rings, which are connected through carbamide bridges or optionally, in addition
also through other bridging structures. The structure of such aramids may be elucidated
by the following general formula of repeating units:
(-NH-A1-NH-CO-A2-CO)n
wherein A1 and A2 are the same or different and signify aromatic and/or polyaromatic
and/or heteroaromatic rings, that may also be substituted. Typically A1 and A2 may
independently from each other be selected from 1,4-phenylene, 1,3-phenylene, 1,2-phenylene,
4,4'-biphenylene, 2,6-naphthylene, 1,5-naphthylene, 1,4-naphthylene, phenoxyphenyl-4,4'-diyelen,
phenoxyphenyl-3,4'-diylen, 2,5-pyridylene and 2,6-quinolylene which may or may not
be substituted by one or more substituents which may comprise halogen, C1-C4-alkyl,
phenyl, carboalkoxyl, C1-C4-alkoxyl, acyloxy, nitro, dialkylamino; thioalkyl, carboxyl
and sulfonyl. The -CONH-group may also be replaced by a carbonyl-hydrazide (-CONHNH-)
group, azo-or azoxygroup.
[0027] These aramids are generally prepared by polymerization of diacid chloride, or the
corresponding diacid, and diamine.
[0028] Examples of aramids are poly-m-phenylene-isophthalamide and poly-p-phenylene-terephthalamide.
[0029] Additional suitable aromatic polyamides are of the following structure:
(-NH-Ar1-X-Ar2-NH-CO-Ar1-X-Ar2-CO-)n
in which X represents O, S, SO2, NR, N2, CR2, CO.
[0030] R represents H, C1-C4-alkyl and Ar1 and Ar2 which may be same or different are selected
from 1,2-phenylene, 1,3-phenylene and 1,4-phenylene and in which at least one hydrogen
atom may be substituted with halogen and/or C1-C4-alkyl.
[0031] Further useful polyamides are disclosed in
U.S. Pat. No. 4,670,343 wherein the aramid is a copolyamide in which preferably at least 80% by mole of the
total A1 and A2 are 1,4-phenylene and phenoxyphenyl-3,4'-diylene which may or may
not be subsituted and the content of phenoxyphenyl-3,4'-diylene is 10% to 40% by mole.
[0032] Additives may be used with the aramid and, in fact, it has been found that up to
as much as 10% by weight, of other polymeric materials may be blended with the aramid
or that copolymers may be used having as much as 10% of other diamine substituted
for the diamine of the aramid or as much as 10% of other diacid chloride substituted
for the diacid chloride of the aramid.
[0033] In addition to the at least one polymeric structure comprising amino groups, the
non thermoplastic fibrous material of the invention may also comprise at least one
thermoplastic polymer. Such thermoplastic polymer includes polyvinylchloride, nylon,
polyfluorocarbon, polyethylene, polypropylene and mixtures thereof.
[0034] "Constant and uniformly distributed electromagnetic field ", as used herein, means
an electromagnetic field which is radially symmetric and axially invariant. Such an
electromagnetic field may be produced by a microwave reactor. "Microwave", as used
herein, means electromagnetic radiation in the range of frequency from 5 MHz to 500
GHz. Because of Government regulation and the present availability of magnetron power
sources, the frequency normally is 915 or 2450 MHz for industrial applications.
[0035] The microwave reactor suitable for the present invention is a single mode microwave
reactor with a cylindrical geometry. In such a geometry, when the fibrous material
is a fiber, the electromagnetic field is predictable, uniformly distributed around
the fiber.
[0036] This circular cross section reactor, depicted in figures 2 and 3 combines the radially
symmetric electromagnetic field distributions and the well defined axial electromagnetic
field profile.
[0037] An example of a particularly suitable reactor for the invention is the single mode
TM010 (Transverse Magnetic 010 mode) cylindrical resonant cavity, described in
A.C. Metaxas and R.J. Meredith, Industrial Microwave Heating, Peter Peregrinus Ltd.,
London, England, 1983, pp. 183-193, equipped with an American Microwave Technology (AMT) solid-state amplifier as microwave
power source, 32.7 cm wavelength, powered from a 28 VDC power supply and with a maximum
power level of 400W, with dimensions of an inner length (L) of 30 cm and an inner
radius (R) of 12.5 cm and generating a resonant frequency of 915 MHz.
[0038] Associations in series or in parallel or any suitable arrangements of the previously
described cavities are considered to be part of the scope of the invention.
[0039] "Under low tension", as used herein, means substantially very low tension. When the
fibrous material is any fibrous structure but a fiber, it is preferably submitted
to no tension at all. When the fibrous material is a fiber, the tension is preferably
less than 0.2 gpd (grams per denier).
[0040] "Permanence", as used herein, is measured according to the following test: the permanently
shaped non thermoplastic fibrous material obtained through the process of the invention
is "unshaped" : in other words, the basic fibrous material composing the permanently
shaped fibrous material is taken back to the original linear position it had before
it was ever imparted a shape. For instance, if the permanently shaped fibrous material
is a twisted fiber, it is untwisted; if it is a crimped fiber, it is uncrimped; if
it is a knitted fabric, it is unknitted so that the fibrous material is extented in
its original linear position. This "unshaping process" must be done under a certain
tension because of the natural elasticity acquired by the fibrous material through
the process of the invention. Once the fibrous material is completely unshaped, ie
once it is back to its linear original position, it is relieved of any tension and
freed to come back to the shape it had before the "unshaping" process. By comparing
the respective level of the shape of the fibrous material before and after the "unshaping"
process, one can then measure the percentage of shape retention of the fibrous material.
This percentage is the permanence of the shape. With the process of the invention,
the permanence is at least 30%, preferably at least 50%, and more preferably at least
70%. That means that a shaped fibrous material submitted to the process of the invention
retains at least 30% of its shape after "unshaping". When the shaped fibrous material
is a twisted fiber, the fiber retains at least 70%, preferably at least 80%, more
preferably at least 90%, and even more preferably at least 96%, of the twist imparted,
this twist being measured as described in the examples below.
[0041] The process of the invention allows to impart to para-aramid fibers permanent high
twist level never reached before. For instance, for industrial fibers, the optimum
twist level Tpm (turns per meter) is calculated for a generally accepted twist multiplier
TM of 1.1 using the following relationship given in ASTM D 885-98 as formula (10).
[0042] As an example for a 1670 dtex para-aramid fiber and a TM of 1.1, the optimum calculated
twist level is about 80 tpm. This value is given by:
[0043] In the case of a para-aramid fiber of a dtex of 1670 first twisted at 500 tpm and
then submitted to the process of the invention, a permanent twist level of 400 tpm
is observable.
[0044] In one embodiment of the invention, the fibrous material is a fiber. "Fiber", as
used herein, means a fibrous material having a length at least 1000 times its diameter
or width. The fibers are preferably polyamide fibers and more preferably aramid fibers.
Fibers which are exclusively composed of aromatic polyamides are preferred. Para-aramid
fibers which are formed of poly(p-phenylene terephthalamide) are more preferred.
[0045] Preferably, the fiber has a modulus of about 10 to about 2500 g/den, preferably of
about 1000 to about 2500 g/den, and a tenacity of about 3 to about 50 g/den, preferably
of about 3 to about 38 g/den. The modulus and the tenacity are measured according
to the ASTM D 885-98 method.
[0046] The fibers are generally spun from an anisotropic spin dope using an air gap spinning
process such as is well known and is described in United States Patent No.
3,767,756 or
4,340,559. Fibers are spun from an anisotropic spin dope at about 80°C, through an air gap,
into an aqueous coagulating bath of about 5°C, and through an aqueous rinse and wash.
The resulting fibers are so-called "never-dried" and include at least 0.05% by weight,
preferably from 0.05 to 400%, by weight, water, this water content being measured
according to ASTM D885-98 for the moisture regain level. This water is uniformly distributed
along the length of the fiber.
[0047] It is possible to use never-dried or partially or totally dried fibers as the fibrous
material for the process of the invention : in the case of totally dried fibers, it
is important that the fiber be immersed in an aqueous composition for several hours
prior to the microwave processing, so that they include at least 0.05 weight % of
an aqueous composition.
[0048] It is also possible to use fibers comprising mixtures of the above materials including
hybrid fibers, blends of different fibers such as natural and man made fibers. Furthermore,
two-component fibers may also be used in accordance with the invention, for instance
fibers in which the core consists of a different material from the skin or in which
the various filaments are from different nature.
[0049] The fibers suitable for the present invention may be round, flat or may have another
cross-sectional shape or they may be hollow fibers.
[0050] In a preferred embodiment of the invention, the shaped fibrous material is a twisted
fiber.
[0051] The shaped fibrous material, preferably the twisted fiber, is processed through the
constant and uniformly distributed electromagnetic field at a speed which may be adjusted
between 0.01 and 2000 m/min. Typical speeds are 60 m/min for the fibrous material
treatment other than during the spinning process, and 800 m/min for the speed during
the manufacturing of the fibrous material.
[0052] During the process of the invention, the fibrous material is maintained at a very
low tension. It preferably undergoes no tension at all. When the fibrous material
is a fiber, the tension is preferably less than 0.2 g/d.
[0053] It is very important that the fibrous material be not degraded during the process
of the invention. In this view, the rate of the increase of temperature of the fibrous
material is less than 300°C/s during the time it is submitted to the electromagnetic
field. In a preferred embodiment of the invention, the dwell time of the fibrous material
in the microwave reactor is more than 0.1 s, and more preferably it is the necessary
time so that the difference between the temperature of the outcoming fibrous material
and the temperature of the incoming fibrous material is less than 300°C.
[0054] The temperature of the incoming fibrous material may be selected and is only limited
by the temperature resistance of the components, this being valid for very low as
well as very high temperatures. Nonetheless a range of 10 °C to 100 °C is preferred,
with a range of from 15 °C to 45 °C being more preferred.
[0055] When the fibrous material is a fiber, the fiber path may be a linear trajectory perfectly
coinciding with the reactor main central axis, as shown on fig 2. The fiber path may
alternatively be sinusoidal as shown in figure 3: in such a case, one obtains a periodically
varying electromagnetic profile along the fiber which can result in special fiber
mechanical and chemical properties uniformly distributed along the fiber length. Furthermore
the sinusoidal fiber path can be offset from the geometric center of the reactor producing
similar effects. Alternatively inserts placed appropriately in the reactor can be
engineered to produce a similar periodic fiber treatment. Additionally, such inserts,
with for example variable thickness, can be used to produce a gradient distribution
of the axial electromagnetic field matching the variation of absorbency of the fiber
from its entry in the reactor to its outlet. This later case can be used for the linear
fiber path still producing a gradient from the inlet to the outlet of the reactor.
Other variations, such as a sinusoidal fiber path with variable amplitude, or a non-circular
but oval cavity cross section, are possible within the scope of the invention which
should not be restricted to the above alternate constructions and fiber path configurations.
[0056] In a preferred embodiment, nitrogen or air can be circulated through the reactor
to evacuate water vapor.
[0057] At the exit of the microwave reactor, the temperature of the outcoming fibrous material
is preferably less than 100°C, and more preferably less than 45°C.
[0058] At the exit of the microwave reactor, the fibrous material may undergo an additional
treatment. For instance, it may be further heated or surface treated or coated with
various polymeric solutions, like epoxy-latex formulations for a pneumatic production
line. It can also be subject to a plasma, an electrostatic discharge, or a corona
treatment.
[0059] With the specific design of the reactor of the process of the invention, the fiber,
which initially has a fixed microwave loss factor along its length, is exposed to
the same electromagnetic field strength over its entire length, except for the inlet
and outlet which are special boundaries. The fiber therefore undergoes an isotropic
treatment all along its length and therefore shows constant properties as regards
tenacity, modulus, residual water content, twist uniformity and permanent shaping.
[0060] The permanently shaped fibers obtained through the process of the present invention
show no internal cracks. Their morphology and density remain almost unchanged. They
exhibit no shrinkage during the process They usually have a specific breaking strength
of about 2.65 to about 33.5 cN/dtex (about 3 to about 38 g/den, preferably about 15
to about 38 g/den) and a specific modulus of about 8.83 to about 2297 cN/dtex (about
10 to about 2500 g/den, preferably about 1000 to about 2500 g/den).
[0061] The invention will be explained in more detail with reference to the following examples.
EXAMPLES
Example 1
[0062] A regular bobbin of Kevlar® 29 para-aramid yarn made of 1000 filaments of 1.5 denier
per filament, equivalent to a total of 1670 dtex linear density, has been used as
a feed material for all the examples cited below. This material is thereafter referred
to as K29. The moisture content measured on K29 using ASTM D885-98 is 5.9 weight percent.
[0063] A sufficient amount of K29 yarn has been twisted, using a SAURER ALLMA® elasto-twister
AZB 200/240 Kevlar® set at 500 tpm, and directly wound on plastic cylindrical tubes,
which tubes are known to resist to water exposure without appreciable swelling or
shrinkage. The twisted 500 tpm K29 yarn is thereafter referred to as M3D. Using a
twist counter, Zeigle D311, the real tpm was confirmed to be 609 tpm which is quite
a usual divergence vs. the set point of 500 tpm since it is a high twist level using
a manual control of the twisting machine.
[0064] A 50 cm sample of M3D is freed to relax and let untwist to its natural equilibrium
level. Using a twist counter, the relaxed sample of M3D is untwisted completely to
measure the residual twist. The zero twist level is confirmed by driving a pin through
the middle and along the axis of the filament bundle. One should be able to freely
move the pin in the axial direction from one boundary of the sample to the other without
being stopped by a blockage of the pin. The residual twist level was measured to be
309 tpm , i.e. 51% of the initial twist. The permanence is therefore 51%. The water
content of the relaxed sample remains unchanged at about 5.9 weight percent.
[0065] The SEM (Scanning Electron Micrograph) analysis of the morphology of a sample of
M3D shows that the filaments are unchanged and in particular no crack parallel with
the longitudinal axis of the filaments have been observed. Fig. 4 shows the cross
section of a bundle of filaments of M3D and Fig. 4a of the unaltered cross section
of a single filament of M3D. By unaltered cross section is meant that the cross section
is undamaged, in other words that there are no cracks across the section.
Example 2
[0066] A sufficient amount of K29 yarn has been twisted, using a SAURER ALLMA® elasto-twister
AZB 200/240 Kevlar® set at 500 tpm, and directly wound on plastic cylindrical tubes,
which tubes are known to resist to water exposure without appreciable swelling or
shrinkage. The twisted 500 tpm K29 yarn is thereafter referred to as M3D. Using a
twist counter, Zeigle D311, the real tpm was confirmed to be 617 tpm which is quite
a usual divergence vs. the set point of 500 tpm since it is a high twist level using
a manual control of the twisting machine.
[0067] A sufficient number of bobbins of M3D were immersed for 48 hours in a recipient containing
de-ionised water; the resulting fiber is hereinafter referred to as M1500. The moisture
content measured on M1-500 using ASTM D885-98 is 22.1 weight percent.
[0068] A 50 cm sample of M1-500 is freed to relax and let untwist to its natural equilibrium
level. Using a twist counter the relaxed sample of M1-500 is untwisted completely
to measure the residual twist. The zero twist level is confirmed by driving a pin
through the middle and along the axis of the filament bundle. One should be able to
freely move the pin in the axial direction from one boundary of the sample to the
other without being stopped by a blockage of the pin. The residual twist level was
measured to be 409 tpm , i.e. 66 % of the initial twist. The permanence is therefore
66%.
[0069] The SEM (Scanning Electron Micrograph) analysis of the morphology of a sample of
M1-500 shows that the filaments are unchanged and in particular no crack parallel
with the longitudinal axis of the filaments have been observed. Fig. 5 shows the cross
section of a bundle of filaments of M1-500 and Fig. 5a of the unaltered cross section
of a single filament of M1-500.
Example 3
[0070] A sufficient amount of K29 yarn has been twisted, using a SAURER ALLMA® elasto-twister
AZB 200/240 Kevlar® set at 500 tpm, and directly wound on plastic cylindrical tubes,
which tubes are known to resist to water exposure without appreciable swelling or
shrinkage. The twisted 500 tpm K29 yarn is thereafter referred to as M3D. Using a
twist counter, Zeigle D311, the real tpm was confirmed to be 611 tpm which is quite
a usual divergence vs. the set point of 500 tpm since it is a high twist level using
a manual control of the twisting machine.
[0071] A sufficient number of bobbins of M3D were immersed for 48 hours in a recipient containing
de-ionised water. A bobbin was taken off the recipient and was fed at 6 meters per
minute to the off-line treatment unit of figure 1. The corresponding resident time
in the cylindrical TM010 resonant cavity was 3 seconds. The resonant cylindrical cavity
is depicted on Fig. 2 which also provides its dimensions. The fiber temperature entering
the cavity was about 20 degree centigrade compared to less than 40 degree centigrade
for the "treated" fiber exiting the cavity. The water content, using ASTM D885-98
method, of the fiber entering the cavity was 22.1 weight percent compared to 18.8
weight percent for the "treated" fiber exiting the cavity. The exiting fiber, referred
thereinafter as to M3A, was wound onto cylindrical plastic tubes.
[0072] A 50 cm sample of M3A is freed to relax and let untwist to its natural equilibrium
level. Using a twist counter the relaxed sample of M3A is untwisted completely to
measure the residual twist. The zero twist level is confirmed by driving a pin through
the middle and along the axis of the filament bundle. One should be able to freely
move the pin in the axial direction from one boundary of the sample to the other without
being stopped by a blockage of the pin. The residual twist level was measured to be
589 tpm , i.e. 96 % of the initial twist. The permanence is therefore 96%.
[0073] The SEM (Scanning Electron Micrograph) analysis of the morphology of a sample of
M3A shows that the filaments are unchanged and in particular no crack parallel with
the longitudinal axis of the filaments have been observed. Fig. 6 shows the cross
section of a bundle of filaments of M3A and Fig. 6a of the unaltered cross section
of a single filament of M3A.
Example 4
[0074] A sufficient amount of K29 yarn has been twisted, using a SAURER ALLMA® elasto-twister
AZB 200/240 Kevlar® set at 500 tpm, and directly wound on plastic cylindrical tubes,
which tubes are known to resist to water exposure without appreciable swelling or
shrinkage. The twisted 500 tpm K29 yarn is thereafter referred to as M3D. Using a
twist counter, Zeigle D311, the real tpm was confirmed to be 604 tpm which is quite
a usual divergence vs. the set point of 500 tpm since it is a high twist level using
a manual control of the twisting machine.
[0075] A bobbin of M3D was fed at 6 meters per minute to the off-line treatment unit of
figure 1. The corresponding resident time in the cylindrical TM010 resonant cavity
was 3 seconds. The resonant cylindrical cavity is depicted on Fig. 2 which also provides
its dimensions. The fiber temperature entering the cavity was about 20 degree centigrade
compared to less than 40 degree centigrade for the "treated" fiber exiting the cavity.
The water content, using ASTM D885-98 method, of the fiber entering the cavity was
5.9 weight percent compared to 1.5 weight percent for the "treated" fiber exiting
the cavity. The exiting fiber, referred thereinafter as to M3C, was wound onto cylindrical
plastic tubes.
[0076] A 50 cm sample of M3C is freed to relax and let untwist to its natural equilibrium
level. Using a twist counter the relaxed sample of M3C is untwisted completely to
measure the residual twist. The zero twist level is confirmed by driving a pin through
the middle and along the axis of the filament bundle. One should be able to freely
move the pin in the axial direction from one boundary of the sample to the other without
being stopped by a blockage of the pin. The residual twist level was measured to be
483 tpm, i.e. 80 % of the initial twist. The permanence is therefore 80%.
[0077] The SEM (Scanning Electron Micrograph) analysis of the morphology of a sample of
M3C shows that the filaments are unchanged and in particular no crack parallel with
the longitudinal axis of the filaments have been observed. Fig. 7 shows the cross
section of a bundle of filaments of M3C and picture Fig. 7a of the unaltered cross
section of a single filament of M3C.
Example 5
[0078] A sufficient amount of K29 yarn has been twisted, using a SAURER ALLMA® elasto-twister
AZB 200/240 Kevlar® set at 500 tpm, and directly wound on plastic cylindrical tubes,
which tubes are known to resist to water exposure without appreciable swelling or
shrinkage. The twisted 500 tpm K29 yarn is thereafter referred to as M3D. Using a
twist counter, Zeigle D311, the real tpm was confirmed to be 583 tpm which is quite
a usual divergence vs. the set point of 500 tpm since it is a high twist level using
a manual control of the twisting machine.
[0079] A sufficient number of bobbins of M3D were immersed for 48 hours in a recipient containing
de-ionised water. A bobbin was taken off the recipient and was fed at 50 meters per
minute to the off-line treatment unit of figure 1. The corresponding resident time
in the cylindrical TM010 resonant cavity was 0.4 seconds. The resonant cylindrical
cavity is depicted on Fig. 2 which also provides its dimensions. The fiber temperature
entering the cavity was about 20 degree centigrade compared to less than 40 degree
centigrade for the "treated" fiber exiting the cavity. The water content, using ASTM
D885-98 method, of the fiber entering the cavity was 22.1 weight percent. An almost
unchanged weight percent for the "treated" fiber exiting the cavity was found. The
exiting fiber, referred thereinafter as to M4A, was wound onto cylindrical plastic
tubes.
[0080] A 50 cm sample of M4A is freed to relax and let untwist to its natural equilibrium
level. Using a twist counter the relaxed sample of M4A is untwisted completely to
measure the residual twist. The zero twist level is confirmed by driving a pin through
the middle and along the axis of the filament bundle. One should be able to freely
move the pin in the axial direction from one boundary of the sample to the other without
being stopped by a blockage of the pin. The residual twist level was measured to be
357 tpm , i.e. 61 % of the initial twist. The permanence is therefore 61%.
[0081] The SEM (Scanning Electron Micrograph) analysis of the morphology of a sample of
M4A shows that the filaments are unchanged and in particular no crack parallel with
the longitudinal axis of the filaments have been observed. Fig. 8 shows the cross
section of a bundle of filaments of M4A and Fig. 8a of the unaltered cross section
of a single filament of M4A.
SAMPLE REFERENCE |
INITIAL TWIST |
RELAXED RESIDUAL TWIST |
Permanence % RESIDUAL TWIST |
M3D control Example 1 |
609 |
309 |
51 |
M 1-500 Example 2 |
617 |
409 |
66 |
M3A Example 3 |
611 |
589 |
96 |
M3C Example 4 |
604 |
483 |
80 |
MA4 Example 5 |
583 |
357 |
61 |
[0082] These results show that a fibrous material submitted to the process of the invention
can retain up to 96% of its shape.
1. Verfahren zum Verleihen von Permanenz einem geformten nichtthermoplastischen Fasermaterial,
das Aminogruppen umfasst, umfassend das Unterwerfen des geformten nichtthermoplastischen
Fasermaterials unter geringer Spannung einem konstanten und gleichförmig verteilten
elektromagnetischen Feld, das durch einen zylindrischen, im quermagnetischen 010-Einzelmodus
arbeitenden Mikrowellenreaktor resonanter Kavität erzeugt wird, wobei die Temperaturerhöhungsrate
des Materials weniger als 300 °C/s beträgt.
2. Verfahren nach Anspruch 1, umfassend das Unterwerfen des geformten nichtthermoplastischen
Fasermaterials unter geringer Spannung einem konstanten und gleichförmig verteilten
elektromagnetischen Feld, das durch einen zylindrischen, im quermagnetischen 010-Einzelmodus
arbeitenden Mikrowellenreaktor resonanter Kavität erzeugt wird,
- wobei das konstante und gleichförmig verteilte elektromagnetische Feld mit Frequenzen
von 5 MHz bis 500 GHz betrieben wird,
- das geformte nichtthermoplastische Fasermaterial durch das konstante und gleichförmig
verteilte elektromagnetische Feld mit einer Rate von 0,01 bis 1200 m/min bearbeitet
wird,
- die Temperaturerhöhungsrate des geformten nichtthermoplastischen Fasermaterials
weniger als 300 °C/s beträgt,
- das geformte nichtthermoplastische Fasermaterial i) mindestens ein polymeres Gefüge,
das Aminogruppen umfasst, und ii) mindestens 0,05 Gew.-% einer wässrigen Zusammensetzung
umfasst.
3. Verfahren nach Anspruch 2, wobei das polymere Gefüge, das Aminogruppen umfasst, Polyamide,
Polyamine, Polyimide, Aramide, Vermischungen und Mischungen davon umfasst.
4. Verfahren nach Anspruch 3, wobei das polymere Gefüge, das Aminogruppen umfasst, ein
Aramid ist.
5. Verfahren nach Anspruch 4, wobei das Aramid Poly-m-phenylenisophthalamid und Poly-p-phenylenterephthalamid
umfasst.
6. Verfahren nach Anspruch 2, wobei das nichthermoplastische Fasermaterial auch mindestens
ein thermoplastisches Polymer umfasst.
7. Verfahren nach Anspruch 2, wobei die wässrige Zusammensetzung Wasser ist, das in dem
Fasermaterial in freier und gebundener Form vorliegt.
8. Verfahren nach Anspruch 2, wobei die Temperatur des austretenden Fasermaterials weniger
als 45 °C beträgt.
9. Verfahren nach Anspruch 2, wobei das Fasermaterial eine Faser ist.
10. Verfahren nach Anspruch 9, wobei die Faser gedreht ist.
11. Verfahren nach Anspruch 9, wobei die Faser einer Spannung von weniger als 0,2 g/d
unterworfen wird.
12. Verfahren nach Anspruch 1 zum Verleihen von Permanenz einer gedrehten Para-Aramidfaser,
umfassend das Unterwerfen der Faser unter einer Spannung von weniger als 0,2 gpd einem
konstanten und gleichförmig verteilten elektromagnetischen Feld, das durch einen zylindrischen,
im quermagnetischen 010-Einzelmodus arbeitenden Mikrowellenreaktor resonanter Kavität
erzeugt wird,
- wobei das gleichförmig verteilte elektromagnetische Feld mit Frequenzen von 5 MHz
bis 500 GHz betrieben wird,
- die Faser mit einer Rate von 0,01 bis 1200 m/min durch den Mikrowellenreaktor bearbeitet
wird,
- die Temperaturerhöhungsrate der Faser weniger als 300 °C/s beträgt,
- die Faser mindestens 0,05 Gew.-% einer wässrigen Zusammensetzung umfasst.
1. Procédé permettant de conférer la permanence à un matériau fibreux non thermoplastique
profilé comprenant des groupes amino, comprenant la soumission sous faible tension,
dudit matériau fibreux non thermoplastique profilé à un champ électromagnétique constant
et réparti de manière uniforme généré par un réacteur micro-ondes en cavité résonnante
cylindrique en mode transverse magnétique 010 mode unique, la vitesse d'augmentation
de la température du matériau étant inférieure à 300°C/s.
2. Procédé selon la revendication 1 comprenant la soumission, sous faible tension, du
matériau fibreux non thermoplastique profilé à un champ électromagnétique constant
et réparti de manière uniforme généré par un réacteur micro-ondes en cavité résonnante
cylindrique en mode transverse magnétique 010 mode unique,
- le champ électromagnétique constant et réparti de manière uniforme fonctionnant
à des fréquences de 5 MHz à 500 GHz,
- le matériau fibreux non thermoplastique profilé étant transformé par le champ électromagnétique
constant et réparti de manière uniforme à une vitesse de 0,01 à 1 200 m/min,
- la vitesse d'augmentation de la température du matériau fibreux non thermoplastique
profilé étant inférieure à 300°C/s,
- le matériau fibreux non thermoplastique profilé comprenant i) au moins une structure
polymère comprenant des groupes amino et ii) au moins 0,05 % en poids d'une composition
aqueuse.
3. Procédé selon la revendication 2, dans lequel la structure polymère comprenant des
groupes amino inclut des polyamides, des polyamines, des polyimides, des aramides,
des associations et leurs mélanges.
4. Procédé selon la revendication 3, dans lequel la structure polymère comprenant les
groupes amino est un aramide.
5. Procédé selon la revendication 4, dans lequel l'aramide inclut du poly-m-phénylène-isophtalamide
et du poly-p-phénylène-téréphtalamide.
6. Procédé selon la revendication 2, dans lequel le matériau fibreux non thermoplastique
comprend également au moins un polymère thermoplastique.
7. Procédé selon la revendication 2, dans lequel la composition aqueuse est de l'eau
présente dans le matériau fibreux sous des formes libres et liées.
8. Procédé selon la revendication 2, dans lequel la température du matériau fibreux sortant
est inférieure à 45°C.
9. Procédé selon la revendication 2, dans lequel le matériau fibreux est une fibre.
10. Procédé selon la revendication 9, dans lequel la fibre est torsadée.
11. Procédé selon la revendication 9, dans lequel la fibre est soumise à une tension inférieure
à 0,2 g/d.
12. Procédé selon la revendication 1, permettant de conférer la permanence à une fibre
torsadée de para-aramide comprenant la soumission de ladite fibre, sous une tension
inférieure à 0,2 gpd, à un champ électromagnétique constant et réparti de manière
uniforme produit par un réacteur micro-ondes en cavité résonnante cylindrique en mode
transverse magnétique 010 mode unique,
- le champ électromagnétique uniformément réparti fonctionnant à des fréquences de
5 MHz jusqu'à 500 GHz,
- la fibre étant transformée par le réacteur micro-ondes à une vitesse de 0,01 à 1
200 m/min,
- la vitesse d'augmentation de température de la fibre étant inférieure à 300°C/s,
- la fibre comprenant au moins 0,05 % en poids d'une composition aqueuse.