U.S. patent application number 12/029312 was filed with the patent office on 2009-01-01 for method and device for manufacturing splittable fibers and use thereof.
This patent application is currently assigned to CARL FREUDENBERG KG. Invention is credited to Ararad EMIRZE, Norbert GOFFING, Klaus KLEIN, Engelbert LOCHER.
Application Number | 20090004943 12/029312 |
Document ID | / |
Family ID | 39628232 |
Filed Date | 2009-01-01 |
United States Patent
Application |
20090004943 |
Kind Code |
A1 |
LOCHER; Engelbert ; et
al. |
January 1, 2009 |
Method and device for manufacturing splittable fibers and use
thereof
Abstract
The invention relates to a method and a device (2) for
manufacturing splittable fibers (1), by means of which it is
possible to conduct the melt streams of the two or more mutually
incompatible polymer components (A, B) in the melt spinning process
in such a way that the flow of one polymer stream around individual
polymer streams, or intermingling of the various polymer streams,
is prevented, in particular for greatly different weight
proportions of the polymer components (A, B). For this purpose,
distribution holes (6) are provided upstream from at least one
spinning capillary (4), and the cross-sectional area of the at
least one distribution hole (6) associated with a particular
polymer component (A, B) is adjusted as a function of the
volumetric flow of the particular polymer component (A, B).
Inventors: |
LOCHER; Engelbert; (Worms,
DE) ; KLEIN; Klaus; (Fockelberg, DE) ;
GOFFING; Norbert; (Neunkirchen, DE) ; EMIRZE;
Ararad; (Kaiserslautern, DE) |
Correspondence
Address: |
GROSSMAN, TUCKER, PERREAULT & PFLEGER, PLLC
55 SOUTH COMMERICAL STREET
MANCHESTER
NH
03101
US
|
Assignee: |
CARL FREUDENBERG KG
Weinheim
DE
|
Family ID: |
39628232 |
Appl. No.: |
12/029312 |
Filed: |
February 11, 2008 |
Current U.S.
Class: |
442/401 ;
264/177.2; 425/113 |
Current CPC
Class: |
D01D 5/30 20130101; Y10T
442/681 20150401; D01F 8/12 20130101 |
Class at
Publication: |
442/401 ;
264/177.2; 425/113 |
International
Class: |
D04H 5/00 20060101
D04H005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 2007 |
DE |
102007006756.0-26 |
Jul 24, 2007 |
DE |
102007034687.7-26 |
Claims
1. Method for manufacturing splittable fibers by means of a melt
spinning process, using at least two mutually incompatible polymer
components, wherein distribution holes are provided upstream from
the at least one spinning capillary, and the cross-sectional area
of the at least one distribution hole associated with a particular
polymer component is adjusted as a function of the volumetric flow
of the particular polymer component.
2. Method according to claim 1, wherein the cross-sectional area of
the distribution hole associated with a particular polymer
component is adjusted in such a way that the ratio of the sums of
the cross-sectional areas of the distribution holes % associated
with a particular polymer component approximately corresponds to or
is equal to the volumetric flow ratio of the polymer components
used, with a deviation of 0 to less than or equal to 20%,
preferably less than or equal to 10%, and the volumetric flow ratio
is not equal to 1.
3. Method according to claim 1, wherein the minimum proportion of
one polymer component is less than or equal to 20% by weight,
preferably less than or equal to 10% by weight, particularly
preferably less than or equal to 5% by weight, very particularly
preferably less than or equal to 3% by weight.
4. Method according to claim 1, wherein the distribution holes are
used in circular, curved, slotted, star-shaped, and/or polygonal,
in particular triangular or quadrangular, cross-sectional
shapes.
5. Method according to claim 1, wherein the distribution holes are
configured in a circular pattern, star pattern, and/or in a
row.
6. Method according to claim 1, wherein the mutually incompatible
polymer components are associated with the respective distribution
holes in an individually alternating or blockwise alternating
manner.
7. Method according to claim 6, wherein the polymer components of
one type are associated with the respective distribution holes in
equally sized blocks.
8. Method according to claim 1, wherein the polymer components are
selected from thermoplastic polymers, including polyesters,
polyolefins, polyethylene and/or polypropylene, polylactates and/or
polyamides.
9. Method according to claim 1, wherein at least one polymer
component having a lower weight proportion is used as polymer
component with a lower melting temperature.
10. Method according to claim 1, wherein at least one polymer
component having a lower weight proportion is used as adhesive or
binding component for manufacturing splittable fibers or
filaments.
11. Method according to claim 1, wherein the cross-sectional area
of a particular distribution hole is varied by the exchange and/or
addition of component parts.
12. Splittable fibers manufactured by a method according to claim
1.
13. Splittable fibers, manufactured by a method according to claim
1, containing at least two mutually incompatible polymer
components, whereby at least one polymer component has a proportion
of less than or equal to 20% by weight, preferably less than or
equal to 10% by weight, particularly preferably less than or equal
to 5% by weight, very particularly preferably less than or equal to
3% by weight, and the individual polymer components are composed of
segments that are distinctly separate from one another, and
preferably comprise segments having the same size cross-sectional
shape for each particular type of polymer component.
14. Use of splittable fibers according to claim 12 for producing
nonwoven fabrics, in particular for filters, clothing, hygienic or
cleaning products, or tufted products, in particular carpet
backings.
15. Device, for a method according to claim 1, for manufacturing
splittable fibers from at least two mutually incompatible polymer
components by means of a melt spinning process in which
distribution holes are provided upstream from at least one spinning
capillary, and the cross-sectional area of the at least one
distribution hole associated with a particular polymer component is
adjusted to the volumetric flow of the particular polymer
component.
16. Device according to claim 15, wherein the ratio of the sums of
the cross-sectional areas of the distribution holes associated with
a particular polymer component approximately corresponds to or is
equal to the volumetric flow ratio of the polymer components used,
with a deviation of 0 to less than or equal to 20%, preferably less
than or equal to 10%.
17. Device according to claim 15, wherein the distribution holes
have circular, curved, slotted, star-shaped, and/or polygonal, in
particular triangular or quadrangular, cross-sectional shapes.
18. Device according to claim 15, wherein the distribution holes
are configured in a circular pattern, star pattern, and/or in a
row.
19. Device according to claim 15, wherein the distribution holes
are associated with the particular polymer components in an
individually alternating or blockwise alternating manner.
20. Device according to claim 19, wherein the distribution holes
for one type of polymer component are provided in equally sized
blocks.
21. Device according to claim 15, wherein the cross-sectional area
of a particular distribution hole may be varied by the exchange
and/or addition of component parts.
Description
TECHNICAL FIELD
[0001] The invention relates to a method and a device for
manufacturing splittable fibers by means of a melt spinning
process, using at least two mutually incompatible polymer
components, splittable fibers manufactured according to the method,
and use thereof.
PRIOR ART
[0002] Methods and devices are known from EP 0 413 688, U.S. Pat.
No. 5,562,930, and FR 2 647 815 for the manufacture of splittable
fibers by means of a melt spinning process, using at least two
mutually incompatible polymer components. The individual polymer
melt streams are led through distribution plates inside a spinning
head in such a way that the threads exiting the spinning head
consist of multiple elementary threads of the respective polymers
which, viewed in the cross section of the thread, are alternatingly
positioned.
[0003] The use in particular of polyamide 6.6 as one of the
polymers entails high costs for the starting material. In addition,
this starting material makes it necessary to dry the raw material,
generates an electrostatic charge during the spinning process, and
tends to yellow under the effects of light and heat.
[0004] Therefore, there is a need to greatly reduce the proportion
of one polymer component, in particular the polyamide proportion,
in the splittable fibers.
[0005] By use of the known methods, however, the weight ratio of
the polymer components used may be varied primarily in a proportion
of 30:70 to 70:30, since otherwise, separate polymer segments are
no longer obtained, and splitting into microfibers is thus
difficult or even impossible.
[0006] DE 101 15 185 A1 describes a method for manufacturing
splittable fibers from mutually incompatible polymer components A
and B, in which the proportion of polymer component B is reduced to
5 to 25% by weight, by the fact that polymer components A and B are
introduced in the molten state into a spinning head, distributed
into groups of elementary threads, every other elementary thread is
at least partially encased by a polymer component B, combined in
spinnerets to form the splittable fibers, and subsequently drawn.
Polymer component B, as the component having the lower weight
proportion, thus remains as a boundary layer, i.e., a thin skin, at
which separation is to be later performed.
[0007] The division of the polymer melt streams, comprising
components having a lower weight proportion (minor components) and
components having a higher weight proportion (major components),
into numerous individual streams which together form the
multicomponent fiber generally occurs directly above the spinning
capillary.
[0008] For conventional spinneret packs, when the proportions of
two components differ greatly from one another, the major component
in the molten state often tends to flow around the other component
(minor component) inside the nozzle, thus forming a closed outer
shell.
[0009] On account of one of the components flowing around the
other, or the components intermingling, the tendency of the
otherwise incompatible polymers to split is greatly reduced. As a
result, in extreme cases fibers, although composed of polymers
which are actually incompatible, may no longer be splittable by
mechanical means, in particular by use of water jets. In such cases
the component flowing around the other may be removed, at best, by
means of a solvent.
DESCRIPTION OF THE INVENTION
[0010] The object of the invention, therefore, is to provide a
method and a device for manufacturing splittable fibers using a
melt spinning process, by means of which it is possible to conduct
the melt streams of the two or more mutually incompatible polymer
components in the melt spinning process in such a way that the flow
of one polymer stream around individual polymer streams, or
intermingling of the various polymer streams, is prevented, in
particular for greatly different weight proportions of the polymer
components.
[0011] The stated object is achieved by the features of Claim 1 and
Claim 15.
[0012] According to the method for manufacturing splittable fibers
by means of a melt spinning process using at least two mutually
incompatible polymer components, the stated object is achieved
according to the invention by the fact that distribution holes are
provided upstream from the at least one spinning capillary, and the
cross-sectional area of the at least one distribution hole
associated with a particular polymer component is adjusted as a
function of the volumetric flow of the particular polymer
component.
[0013] In this context, fibers are understood to mean staple
fibers, continuous fibers, or filaments. Fibers that are spun into
yarns are also included. The fibers may also be combined into
fleeces, in particular bonded fleeces, for nonwoven fabrics.
[0014] The subclaims state advantageous refinements of the subject
matter of the invention.
[0015] In one preferred embodiment of the method, the
cross-sectional area of the distribution hole associated with a
particular polymer component is adjusted in such a way that the
flow velocities of all affected polymer components are the same,
with a deviation of 0 to less than or equal to 20%, preferably less
than or equal to 10%.
[0016] For this purpose, the ratio of the sum of the
cross-sectional areas of the distribution holes associated with a
particular polymer component to the sum of the cross-sectional
areas of the distribution holes associated with another polymer
component is adjusted in such a way that the ratio corresponds to
the volumetric flow ratio of the polymer components used, with a
deviation of 0 to less than or equal to 20%, preferably less than
or equal to 10%. The volumetric flow ratio is preferably not equal
to 1.
[0017] The flow velocities of all affected polymer streams are thus
adjusted to be at least approximately equal, resulting in segments
that are distinctly separate from one another, preferably segments
having the same size cross-sectional shape, which even for the
weight ratios of 80:20 to 97:3 of two mutually incompatible polymer
components preferably selected for the method may be split
particularly well, even using mechanical methods, in particular
water jets.
[0018] As a result of the minimum proportion of less than or equal
to 20%, preferably less than or equal to 15%, 10%, 5%, or 3% by
weight of a component, in particular comparatively expensive
polymers such as polyamide 6.6, for example, the costs for the
starting materials and end products of multicomponent fibers may be
reduced. Furthermore, undesired properties of a component, for
example yellowing, may be reduced by use of only a minimum
proportion of this component. In addition, significantly decreasing
a proportion of polymer and/or the distinct segmentation of the
polymer components in the fibers may also enhance the capability
for recycling.
[0019] Furthermore, for a very low proportion of the minor
component, when the nonwoven fabric is subsequently dyed the
coloration may be limited to the major component.
[0020] In one preferred embodiment, the method is also ideally
suited for a desired uniform melt distribution of polymers, in
which the viscosity ratio of the polymer components is 1:1 to 10:1,
preferably 1:1 to 7:1, and particularly preferably 1:1 to 4:1.
[0021] The method is also suited for the manufacture of numerous
cross-sectional shapes of the multicomponent fibers.
[0022] Circular, curved, slotted, star-shaped, and/or polygonal, in
particular triangular or quadrangular, cross-sectional shapes are
advantageously used for the distribution holes. The distribution
holes are preferably configured in a circular pattern, in
particular for the manufacture of hollow fibers. Distribution holes
configured in a star pattern or in a row are preferably
selected.
[0023] The configurations and cross-sectional shapes of the
distribution holes are preferably matched to those of the spinning
capillaries.
[0024] For optimal melt flow distribution, the mutually
incompatible polymer components are preferably associated with the
respective distribution holes in an individually alternating or
blockwise alternating manner, with the polymer components of one
type preferably being associated with the respective distribution
holes in equally sized blocks.
[0025] For manufacturing splittable multicomponent fibers,
thermoplastic polymers selected from polyesters, preferably
polyethylene terephthalate (PET), or polyolefins, preferably
polyethylene (PE) and/or polypropylene (PP), or polylactates and/or
polyamides (PA) are preferably used as components.
[0026] For bicomponent fibers, combinations of mutually
incompatible polymer components are selected, preferably composed
of PET and PP, PET and PA6, PET and PA6.6, or PP and PE.
[0027] Cost savings may be realized as a result of the lower weight
proportion, in particular of comparatively expensive polymers such
as polyamide 6.6.
[0028] In addition, the desired properties of the multicomponent
fibers may be precisely controlled by use of specific weight
proportions of the polymers used.
[0029] In a further preferred embodiment of the method, a polymer
component with a lower melting temperature is preferably used as
the polymer component having a lower weight proportion.
[0030] In a further preferred embodiment of the method, a polymer
component having a lower weight proportion is used as adhesive or
binding component. By use of these measures the properties of the
nonwoven fabric thus manufactured may be influenced, and in
particular the degree of bonding or softness thereof may be
adjusted without the need for bonding using water jets.
[0031] The cross-sectional area of a particular distribution hole
is advantageously varied by the exchange and/or addition of
component parts.
[0032] The invention further relates to splittable fibers
manufactured according to a method described above.
[0033] It is advantageous that the splittable fibers manufactured
in particular by use of the above method, containing at least two
mutually incompatible polymer components, whereby the minimum
proportion of one polymer component is less than or equal to 20% by
weight, preferably less than or equal to 10% by weight,
particularly preferably less than or equal to 5% by weight, very
particularly preferably less than or equal to 3% by weight, and the
individual polymer components are composed of segments that are
distinctly separate from one another, preferably comprise segments
having the same size cross-sectional shape for each particular type
of polymer component. It is particularly preferred to manufacture
pie fibers in this manner.
[0034] The splittable fibers manufactured according to the
above-referenced method are used for producing nonwoven fabrics, in
particular for filters, clothing, hygienic or cleaning products, or
tufted products, in particular carpet backings.
[0035] A further object of the invention is to provide a device for
manufacturing splittable fibers, by means of which it is possible
to conduct the melt streams of the two or more mutually
incompatible polymer components in the melt spinning process in
such a way that the flow of one polymer stream around individual
polymer streams, or intermingling of the various polymer streams,
is prevented, even for greatly different weight proportions of the
polymer components. The minimum proportion of one polymer component
is in particular less than or equal to 20% by weight, preferably
less than or equal to 10% by weight, particularly preferably less
than or equal to 5% by weight, very particularly preferably less
than or equal to 3% by weight.
[0036] The object is achieved by the fact that the device has
distribution holes provided upstream from the spinning capillaries,
and the cross-sectional area of the at least one distribution hole
associated with a particular polymer component is adjusted to the
volumetric flow of the particular polymer component.
[0037] The ratio of the sums of the cross-sectional areas of the
distribution holes associated with a particular polymer component
preferably corresponds, at least approximately, to the volumetric
flow ratio of the polymer components used, with a deviation of 0 to
less than or equal to 20%, preferably less than or equal to
10%.
[0038] In one preferred embodiment of the device, the number of the
distribution holes associated with a particular polymer component
and the size of the cross-sectional areas of the distribution holes
associated with a particular polymer component are adapted to one
another in such a way that the flow velocities of all affected
polymer components are essentially the same, with a deviation of 0
to less than or equal to 20%, preferably less than or equal to
10%.
[0039] Depending on the desired cross-sectional shapes of the
splittable fibers to be manufactured, the distribution holes have
corresponding circular, curved, slotted, star-shaped, and/or
polygonal, in particular triangular or quadrangular,
cross-sectional shapes.
[0040] The distribution holes are advantageously configured in a
circular pattern for the manufacture of hollow fibers or filaments.
Distribution holes configured in a star pattern or in a row are
also provided, depending on the desired cross-sectional shape of
the splittable fibers.
[0041] In one preferred embodiment of the device, the distribution
holes are associated with the particular polymer components in an
individually alternating or blockwise alternating manner, with the
distribution holes for one type of polymer component particularly
preferably being provided in equally sized blocks.
[0042] The cross-sectional area of a particular distribution hole
may advantageously be varied by the exchange and/or addition of
component parts.
EXECUTION OF THE INVENTION
[0043] The subject matter of the invention is explained in greater
detail with reference to several examples, without limiting the
invention.
[0044] The invention is described below with reference to preferred
exemplary embodiments, illustrated in the drawings, of distribution
holes provided upstream from the spinning capillaries, compared to
a known system of a distribution plate for a spinning capillary,
each of which are provided for the flowthrough of two mutually
incompatible polymer components A and B in a weight ratio of 20:80
to 3:97. The drawings show the following:
[0045] FIG. 1: shows a top view of a known system and design of a
distribution plate having distribution holes for a spinning
capillary for the flowthrough of polymer components A (gray) and B
(black);
[0046] FIG. 2: shows the flow pattern of polymer components A
(solid arrow) and B (dashed arrow) by use of a known method or by
use of a known device for manufacturing splittable fibers,
according to FIG. 1;
[0047] FIG. 3: shows the flow pattern of the referenced polymer
components A (solid arrow) and B (dashed arrow) by use of the
method according to the invention or by use of the device according
to the invention for manufacturing splittable fibers;
[0048] FIG. 4: shows a top view of a preferred embodiment of
distribution holes configured in a circular pattern and having
circular cross-sectional shapes, with different numbers of
distribution holes for flowthrough of the referenced polymer
components A (gray) and B (black), and in each case having the same
size cross-sectional areas for flowthrough of the referenced
polymer components A and B, with the total cross-sectional areas
for flowthrough of the referenced polymer components A and B being
different;
[0049] FIG. 5: shows a top view of one preferred embodiment of
distribution holes configured in a circular pattern, having
polygonal cross-sectional shapes with different numbers of
distribution holes for flowthrough of the referenced polymer
components A (gray) and B (black), and in each case having the same
size cross-sectional areas for flowthrough of the referenced
polymer components A and B, with the total cross-sectional areas
for flowthrough of the referenced polymer components A and B being
different;
[0050] FIG. 6 shows a top view of one preferred embodiment of
distribution holes configured in a circular pattern, having
circular cross-sectional shapes with the same number of
distribution holes for flowthrough of the referenced polymer
components A (gray) and B (black), with the cross-sectional areas
for flowthrough of the referenced polymer components A and B being
different, both individually and in the sum total;
[0051] FIG. 7 shows a top view of one preferred embodiment of
distribution holes configured in a circular pattern and having
circular cross-sectional shapes for flowthrough of the referenced
polymer components A (gray), and having combined slotted and curved
cross-sectional shapes for flowthrough of the referenced polymer
component B (black), having the same number of cross-sectional
areas for flowthrough of the referenced polymer components A and B,
and with the cross-sectional areas for flowthrough of the
referenced polymer components A and B being different, both
individually and in the sum total;
[0052] FIG. 8: shows a perspective side view of a device according
to the invention for manufacturing splittable fibers from at least
two mutually incompatible polymer components A (gray) and B
(black), in which distribution holes are provided upstream from the
spinning capillary;
[0053] FIG. 9: shows a cross section of a fiber comprising the
referenced polymer components A (gray) and B (white), manufactured
by use of the method according to the invention or by use of the
device according to the invention; and
[0054] FIG. 10: shows a cross section of a fiber comprising the
referenced polymer components A (gray) and B (white), manufactured
by use of a known method or by use of a known device.
[0055] Splittable multicomponent fibers are usually manufactured by
spinning two or more polymers from spinning capillaries of a
spinneret. After the fibers are spun and cooled, the individual
components may be separated from one another at the interfaces of
two polymer components.
[0056] FIG. 1 shows known circular distribution holes 6, configured
in a circular pattern and having the same cross-sectional areas for
flowthrough of mutually incompatible polymer components, for
example polymer components A and B, whereby polymer components A
and B are distributed over the distribution holes 6 in an
individually alternating manner according to the system (AB)n,
where n stands for an integer equal to or greater than 1.
[0057] On account of its greater flow velocity, polymer component B
flows in a divergent manner, thereby displacing or surrounding
polymer component A. This flow pattern of polymer component B
(dashed arrow) and of polymer component A (solid arrow) is
schematically shown in FIG. 2.
[0058] As a result, in particular for the stated weight ratios of
20:80 to 3:97, the fibers composed of polymer components A and B
may no longer be splittable by mechanical means, and, if it is
possible at all, may be split only by use of a solvent. However,
splitting by use of a solvent is particularly disadvantageous
because the solvent must subsequently be removed, and possibly
recycled in a laborious procedure.
[0059] To allow mechanical splitting, in particular by use of water
jets, even for fibers having greatly different weight ratios, a
melt spinning method or a melt spinning device 2 is provided in
which distribution holes 6 are provided upstream from the spinning
capillaries 4, and in their configuration and design are
specifically matched to the polymer components used.
[0060] For this purpose the cross-sectional areas of the
distribution holes 6 associated with a particular polymer component
are mutually adapted to the volumetric flow of the polymer
components in question.
[0061] The flow velocities of all affected polymer components are
set to be at least approximately equal by a corresponding
adjustment of the distribution holes 6 with respect to the number
of the distribution holes 6 associated with a particular polymer
component and with respect to the size of the cross-sectional areas
of the distribution holes 6 associated with a particular polymer
component. This flow pattern is schematically shown in FIG. 3 by
way of example for polymer component B (dashed arrow) and polymer
component A (solid arrow).
[0062] In one preferred embodiment, the ratio of the sum of the
cross-sectional areas of the distribution holes 6 associated with a
particular polymer component to the sum of the cross-sectional
areas of the distribution holes 6 associated with another polymer
component is adjusted in such a way that the ratio corresponds, at
least approximately, to the volumetric flow ratio of the particular
polymer components, i.e., with a deviation of 0 to less than or
equal to 20%, preferably less than or equal to 10%.
[0063] For a volumetric flow ratio of 1:4 for two polymer
components A and B, distribution holes 6 of the same size, for
example, i.e., having the same size cross-sectional areas, and in a
number in a 1:4 ratio and having a blockwise alternating
configuration A BBBB A BBBB . . . , are optimal for a uniform flow
velocity of polymer components A and B through the associated
distribution holes 6.
[0064] FIG. 4 shows the design of distribution holes 6 configured
in a circular pattern with circular cross-sectional shapes. The
ratio of the sums of the cross-sectional areas of the distribution
holes 6 associated with polymer components A (gray) and B (black)
is also 1:4. Polymer components A and B are associated with the
particular distribution holes 6 in particular in a blockwise
alternating manner.
[0065] As an alternative to the circular cross-sectional shape of
the distribution holes 6, other geometries are possible, such as
curved, slotted, star-shaped, and/or polygonal cross-sectional
shapes.
[0066] FIG. 5 shows the design of distribution holes 6 configured
in a circular pattern with polygonal cross-sectional shapes for the
distribution holes 6 associated with polymer components A (gray)
and B (black).
[0067] Alternatively, for a volumetric flow ratio of 1:4 for two
polymer components A and B, differently sized distribution holes 6
may be used. In this case the number of distribution holes 6
associated with polymer components A and B is the same, and the
size of the cross-sectional areas of the distribution holes 6
associated with polymer component B in each case is four times the
size of the cross-sectional areas of the distribution holes 6
associated with polymer component A. Polymer components A and B are
associated with the particular distribution holes 6 in particular
in an individually alternating manner.
[0068] FIG. 6 shows the design of distribution holes 6 configured
in a circular pattern with circular cross-sectional shapes.
[0069] FIG. 7 shows a top view of one preferred embodiment of
distribution holes 6 configured in a circular pattern with circular
cross-sectional shapes for polymer component A, and having combined
slotted and curved cross-sectional shapes for polymer component
B.
[0070] Of course, any other given embodiments having combinations
of any volumetric flow ratios and having distribution holes 6
adapted thereto with regard to the number and size of the
cross-sectional areas in any given cross-sectional shapes are also
provided.
[0071] FIG. 8 illustrates a perspective side view of a device 2
according to the invention for manufacturing splittable fibers 1
from two mutually incompatible polymer components A and B, in which
the distribution holes 6 are provided upstream from the spinning
capillary 4. In this exemplary embodiment, the ratio of the sums of
the cross-sectional areas of the distribution holes 6 associated
with polymer component streams A (gray) and B (black), for a
volumetric flow ratio of 1:3 for polymer components A (gray) and B
(black), is correspondingly 1:3.
[0072] The distribution holes 6 shown in FIGS. 4 through 8 are
optimal for a uniform flow velocity of polymer components A and B
(see FIG. 3).
[0073] As a result of these embodiments, the polymer components
flow in at least approximately equal flow velocities through the
referenced distribution holes 6, so that multicomponent fibers 1
manufactured therefrom, with minimum proportions of one polymer
component of less than or equal to 20% by weight, preferably less
than or equal to 10% by weight, particularly preferably less than
or equal to 5% by weight, or less than or equal to 3% by weight,
have segments 8, 10 that are distinctly separate from one another,
in particular having the same size cross-sectional shapes, as shown
by way of example in FIG. 9 for the referenced polymer components A
(gray) and B (white).
[0074] These cross-sectional shapes are particularly well suited
for splitting, even by mechanical methods, in particular by use of
water jets.
[0075] In contrast, the cross section of a fiber 12, shown by way
of example in FIG. 10, comprising the referenced polymer components
A (gray) and B (white) and manufactured by use of a known method or
by use of a known device, does not have distinctly separate
segments, in particular with respect to polymer component B
(white).
* * * * *