U.S. patent application number 14/331626 was filed with the patent office on 2015-01-15 for bi-component fiber for the production of spunbond fabric.
This patent application is currently assigned to Ewald Dorken AG. The applicant listed for this patent is Ewald Dorken AG. Invention is credited to Daniel Placke, Jorn Schroer.
Application Number | 20150017864 14/331626 |
Document ID | / |
Family ID | 51176869 |
Filed Date | 2015-01-15 |
United States Patent
Application |
20150017864 |
Kind Code |
A1 |
Schroer; Jorn ; et
al. |
January 15, 2015 |
BI-COMPONENT FIBER FOR THE PRODUCTION OF SPUNBOND FABRIC
Abstract
A bi-component fiber (1), in particular for the production of
spunbond fabrics (4), has a first component (2) and a second
component (3), whereby the first component (2) has a first polymer
as an integral part and the second component has a second polymer
as an integral part. It is provided that the difference between the
melting points of the first component (2) and the second component
(3) is less than or equal to 8.degree. C.
Inventors: |
Schroer; Jorn; (Herdecke,
DE) ; Placke; Daniel; (Dortmund, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ewald Dorken AG |
Herdecke |
|
DE |
|
|
Assignee: |
Ewald Dorken AG
Herdecke
DE
|
Family ID: |
51176869 |
Appl. No.: |
14/331626 |
Filed: |
July 15, 2014 |
Current U.S.
Class: |
442/361 ;
428/373 |
Current CPC
Class: |
D01F 8/16 20130101; D04H
1/4382 20130101; D01F 8/06 20130101; D01F 8/04 20130101; D04H 1/492
20130101; Y10T 442/637 20150401; Y10T 428/2929 20150115 |
Class at
Publication: |
442/361 ;
428/373 |
International
Class: |
D01F 8/16 20060101
D01F008/16; D01F 8/06 20060101 D01F008/06; D04H 1/492 20060101
D04H001/492; D01F 8/04 20060101 D01F008/04; D04H 1/4382 20060101
D04H001/4382 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 15, 2013 |
DE |
10 2013 011 700.3 |
Sep 11, 2013 |
DE |
10 2013 014 917.7 |
Claims
1. Bicomponent fiber for the production of spunbond fabrics, with a
first component and a second component, whereby the first component
has a first polymer as an integral part and the second component
has a second polymer as an integral part, characterized in that the
first component and the second component have melting points that
differ from each other by an amount that is less than or equal to
8.degree. C.
2. Bicomponent fiber according to claim 1, characterized in that
the difference between the melting points of the first component
and the second component is between 1.degree. C. to 8.degree.
C.
3. Bicomponent fiber according to claim 1, characterized in that
the difference between the melting points of the first component
and the second component is in a range from 1.degree. C. to
6.degree. C.
4. Bicomponent fiber according to claim 1, characterized in that
the first component and the second component have melt-flow indices
that differ by an amount that is less than or equal to 25 g/10
minutes.
5. Bicomponent fiber according to claim 4, characterized in that
the melt-flow indices of the first component and the second
component in each case are less than or equal to 50 g/10
minutes.
6. Bicomponent fiber according to claim 1, characterized in that
the component that forms an outer surface of the bicomponent fiber
viewed in the cross-section of the fiber has a lower melt-flow
indice than the other component.
7. Bicomponent fiber according to claim 6 characterized in that the
component with the lower melting point surrounds the component with
the higher melting point.
8. Bicomponent fiber according to claim 1, characterized in that
the polymer of one of the two components has been polymerized with
a metallocene catalyst and in that the polymer of the other
component has been polymerized with a Ziegler-Natta catalyst and
has been subjected to a subsequent visbreaking treatment.
9. Bicomponent fiber according to claim 1, characterized in that
the first component has an additive, whereby the proportion by
weight of the additive in the second component is less than in the
first component.
10. Bicomponent fiber according to claim 9, characterized in that
the proportion by weight of the additive in the second component is
at most 50% of the proportion by weight of the additive in the
first component.
11. Bicomponent fiber according to claim 9, characterized in that
the proportion by weight of the additive in the second component is
at most 33% of the proportion by weight of the additive in the
first component.
12. Bicomponent fiber according to claim 9, characterized in that
the additive is selected from the group of a primary antioxidant, a
secondary antioxidant, a UV absorber, a UV stabilizer, a flame
retardant, an antistatic agent, a lubricating agent, a metal
deactivator, a hydrophilizing agent, a hydrophobizing agent, an
anti-fogging additive, a biocide, and mixtures of the
above-mentioned agents.
13. Bicomponent fiber according to claim 9, characterized in that
the additive is selected from the group of: sterically inhibited
phenols, aromatic secondary or tertiary amines, aminophenols,
aromatic nitro compounds or nitroso compounds, organic phosphites
or phosphonates, thioethers, thioalcohols, thioesters, sulfides and
sulfur-containing organic acids, dithiocarbamates,
thiodipropionates, aminopyrazoles, metal-containing chelates,
mercaptobenzimidazoles, hydroxybenzophenones, cinnamates,
oxalanilides, salicylates, resorcinol, monobenzoates,
benzotriazoles, triazines, benzophenones, titanium dioxide, carbon
black, metal-containing complexes of organic sulfur compounds or
phosphorus compounds, sterically hindered amines (HALS), metal
hydroxides, borates, organic bromine-containing compounds or
chlorine-containing compounds, organic phosphorus compounds,
antimony trioxide, melamine, melamine cyanurate, expanded graphite
or other intumescence systems, quaternary ammonium salts, alkyl
sulfonates, alkyl sulfates, alkyl phosphates, dithiocarbamates,
alkaline(-earth) metal carboxylates, polyethylene glycols, as well
as their esters and ethers, ethoxylates, mono- and diglycerides,
fatty alcohols, esters of fatty alcohols, fatty acids, fatty acid
esters, dicarboxylic acid esters, fatty acid amides, metal salts of
fatty acids, polyolefin waxes, natural or synthetic paraffins, and
their derivatives, fluoropolymers and fluoroligomers, anti-blocking
agents such as silicic acids, silicones, silicates, calcium
carbonate, amides of monocarboxylic acids and dicarboxylic acids
and their derivatives, cyclic amides, hydrazones, and
bishydrazones, hydrazides, hydrazines, melamine and its
derivatives, benzotriazoles, aminotriazoles, sterically inhibited
phenols in connection with complexing metal compounds, benzyl
phosphonates, pyridithiols, thiobisphenol esters, polyglycols,
ethoxylates, fluoropolymers and fluoroligomers, montan waxes, in
particular stearates, 10,10'-oxybisphenoxarsine (OBPA),
N-(trihalo-methylthiol)phthalimide, tributyltin oxide, zinc
dimethyl dithiocarbamate, diphenylantimony-2-ethyl hexanoate,
copper-8-hydroxyquinoline, isothiazolones, silver and silver salts
as biocides, and mixtures of the above-mentioned substances.
14. Bicomponent fiber according to claim 1, characterized in that
the first polymer is selected from the group of polyolefins,
polyolefin-copolymers, ethylene polymers, ethylene-copolymers,
propylene, butylene, hexene, octene, mixtures of the
above-mentioned substances, and blends of the above-mentioned
substances.
15. Bicomponent fiber according to claim 1, characterized in that
the second polymer is selected from the group of polyolefins,
polyolefin-copolymers, ethylene polymers, ethylene-copolymers,
propylene, butylene, hexene, octene, mixtures of the
above-mentioned substances, and blends of the above-mentioned
substances.
16. Bicomponent fiber according to claim 1, characterized in that
the proportion by weight of the component with the lower melting
point in the bi-component fiber is at most 50%.
17. Bicomponent fiber according to claim 6, characterized in that
the proportion by weight of the component with the lower melting
point in the bicomponent fiber is at most 25%.
18. Bicomponent fiber according to claim 6, characterized in that
the proportion by weight of the component with the lower melting
point in the bicomponent fiber is at most 10%.
19. Bicomponent fiber according to claim 6, characterized in that
the proportion by weight of the component with the lower melting
point in the bicomponent fiber is at most 5%.
20. Spunbond fabric with at least one bicomponent fiber said at
least one bicomponent fiber being formed a first component and a
second component, whereby the first component has a first polymer
as an integral part and the second component has a second polymer
as an integral part, wherein the first component and the second
component have melting points that differ from each other by an
amount that is less than or equal to 8.degree. C.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a bi-component fiber, in particular
for the production of spunbond fabric, with a first component and a
second component, whereby as integral parts, the first component
has a first polymer and the second component has a second polymer.
In addition, the invention relates to a spunbond fabric with at
least one bi-component fiber of the above-mentioned type.
[0003] 2. Description of Related Art
[0004] Bi-component fibers of the type in question usually have a
first component that consists of a first polymer and a second
component that consists of a second polymer. In this case,
different types of bi-component fibers can be distinguished, which
in each case have different characteristic distributions of the
components in the fiber cross-section. Bi-component fibers, in
which the first component surrounds and thus encompasses the second
component in the cross-section of the fiber, are referred to as
core-sheath fibers. Bi-component fibers, in which both the first
component and the second component form a portion of the fiber
surface in the cross-section of the fiber, are referred to as
side-by-side fibers. Fibers with structures, in which several
strands of a component are embedded in a strand of the other
component, so that an image is produced in the cross-section that
resembles a large number of islands formed from a component, are
referred to as island-in-the-sea fibers. Bi-component fibers, in
which in the cross-section, in each case, a large number of areas
of the respective components are present and form the outer fiber
surface, are referred to as segmented-pie fibers, since the areas
of the individual components in the cross-section routinely have a
pie-wedge-like division. Defined as bi-component fibers in terms of
this application are in this case also expressly those fibers that
have more than 2 components.
[0005] The purpose of the bi-component fibers is to improve the
properties of the fibers or the properties of the spunbond fabric
produced from the fibers. The properties of a spunbond fabric in
this case depend on a host of factors. Some of these factors in the
properties of a spunbond fabric are in this case properties of the
fibers that are used in each case, such as, e.g., their strength.
It is a theory that is widely available and acknowledged at least
in its basic idea that the properties of the resulting bi-component
fiber then represent a combination of the properties of the
individual components of the bi-component fiber, in which the
properties of the individual components complement each other to
the greatest extent possible so that the advantages of the
properties of the two components are combined in the bi-component
fiber. If, for example, a fiber is desired that both has high
strength and shows advantageous behavior when interconnecting the
fibers among themselves in the production of non-woven fabric, it
is thus reasonable to combine a first component with high strength
with a second component that has good connectivity.
[0006] In practice, however, the use of these synergistic effects
is limited to the extent that the properties of the components
cannot routinely be combined in the described, only advantageous
way. Rather, in practice, it is often thus that only a more
advantageous compromise can be achieved by the bi-component fibers
from the properties of the pure components. In this case, in
particular from an improvement of the connectivity of the
bi-component fibers relative to mono-component fibers, the result
is that a non-woven fabric with improved properties, in particular
with improved strength values, can be produced from the fibers.
[0007] Another problem that arises in the case of bi-component
fibers is the limited recyclability of the bi-component fibers in
their production. If unusable product fractions, such as, for
example, scrap, accumulate in the production of products from
bi-component fibers, it is thus desirable to be able to supply
these fractions again to the fiber production as raw material. In
this case, however, it is technically impossible or uneconomical to
separate the components of the bi-component fibers. The recycled
fraction must necessarily, however, be supplied to one of the two
components. In this case, it must be acceptable that the
composition and the properties of the recycled fraction differ from
those of the components to which it is fed. Because of this, the
composition of the component, to which composition the recycled
fraction was added, changes in the resulting bi-component fiber.
The associated change in the properties of the bi-component fiber
is in general undesirable and can be tolerated only up to a certain
degree. This degree to which the change in the properties of the
bi-component fiber can be tolerated therefore determines the limits
of the maximum proportion of recycled material that can be added to
a component.
SUMMARY OF THE INVENTION
[0008] The invention is now based on the object of making available
a bi-component fiber, in particular for the production of a
spunbond fabric, as well as a spunbond fabric with at least one
bi-component fiber, whereby, on the one hand, a better synergistic
effect between the properties of the individual components of the
bi-component fiber can be achieved and, on the other hand, the use
of a higher proportion of recycled material in the production of
the bi-component fibers is possible than is the case in the state
of the art.
[0009] The above-mentioned object is essentially achieved according
to the invention by a bi-component fiber and a spunbond fabric with
the features of the independent claims. The features of the
dependent claims relate to advantageous embodiments.
[0010] According to the invention, the difference between the
melting points of the first component and the second component is
less than or equal to 8.degree. C. It should be pointed out that
any individual intervals or individual values are contained in the
indicated intervals and are to be considered disclosed as essential
to the invention, even if they are not mentioned in detail.
[0011] In connection with the invention, it is advantageous when
the difference between the melting points of the first component
and the second component is at most 6.degree. C. or between
1.degree. C. to 8.degree. C., and preferably between 1.degree. C.
to 6.degree. C. Within these advantageous parameter ranges, the
positive effects of this invention come significantly strongly to
the fore.
[0012] In connection with the invention, it has been shown,
surprisingly enough, that in the case of bi-component fibers, in
which the two components have similar melting points, an
improvement in the synergistic effects between the properties of
the two components can be achieved. This relates in particular to
mechanical properties. For example, it is possible, in the case of
a spunbond fabric produced from bi-component fibers according to
the invention, to increase both the specific tearing force (or
tensile strength) and the specific nail tear resistance (or
nail-tear-out strength). In the case of conventional fibers
according to the state of the art, measures in the production of
spunbond fabrics from these fibers, which were used to increase the
specific tearing forces, routinely accompanied a dropping of the
specific nail tear resistance. In the reverse case, measures for
increasing the specific nail tear resistance routinely resulted in
dropping the specific tearing forces. These disadvantageous effects
can be avoided or at least lessened with bi-component fibers
according to the invention.
[0013] The positive effects of this invention also include the fact
that the proportion of recycled materials, which can be added to
one of the components in the production of the bi-component fiber,
increases relative to conventional fibers. It has been shown that
when components with combined melting points according to the
invention are used, the change in the properties of a component,
which is caused by the addition of recycled material, turns out to
be far less than in conventional fibers.
[0014] In this case, the component with the lower melting point
preferably forms the outer surface of the fiber in the
cross-section of the fiber. The component with the lower melting
point preferably surrounds the component with the higher melting
point. The effect of this advantageous configuration is that the
low-melting component in the sheath area of the fibers ensures
better solidification of the material, and, moreover, improves the
spinning stability and the expandability of the fibers. This
results in an improvement in the softness and/or surface feel of
the spunbond fabric; in addition, the drapability of the fibers is
improved.
[0015] Preferably, the proportion by weight of the component with
the lower melting point in the bi-component fiber is at most 50%,
more preferably at most 25%, even more preferably at most 10%, and
in particular at most 5%. In this case, the bi-component fiber is
especially preferably a core-sheath fiber, whereby the component
with the lower melting point forms the sheath.
[0016] Advantageously, the difference between the melt-flow indices
of the first component and the second component is less than or
equal to 25 g/10 minutes, whereby the melt-flow indices (MFI below)
of the first component and the second component in each case are
less than or equal to 50 g/10 minutes. Preferably, the difference
between the melt-flow indices of the first component and the second
component is less than or equal to 20 g/10 minutes, especially
preferably 15 g/10 minutes, and/or the MFIs of the first component
and the second component are in each case less than or equal to 40
g/10 minutes. Such an advantageous selection of the components
according to the criterion of their MFIs has a positive effect,
surprisingly enough, in a similar way to the selection according to
the invention of the components based on their melting points.
[0017] The positive influence of the advantageous differences
between the MFIs essentially relates to the specific tearing force
and the specific nail tear resistance. These two characteristic
values of a spunbond fabric produced from the fibers can be
improved by the advantageously selected MFIs. In this case, even a
simultaneous increase of the two characteristic values is possible,
but in any case, one of the two characteristic values can be
improved without the other characteristic value deteriorating. This
also has a positive effect on the haptic properties. Thus, the
specific tearing force can be increased without softness and the
so-called "textile grip" being negatively influenced. In this case,
textile grip is defined as a pleasant feeling upon contact.
[0018] In this case, the MFI is measured according to ISO 1133 with
a test load of 2.16 kg and a test temperature of 230.degree. C. The
MFI in this case is also referred to as a melt-flow index or else
as a melt-mass-flow rate (MFR). The determination is made according
to ISO 1133 by the material being melted in a heating cylinder and
being pressed by means of the test load through a defined die. The
MFI is a measurement of the viscosity of the melts of the
respective polymer-containing components. The viscosity in turn is
associated with the degree of polymerization, which corresponds to
the mean number of monomer units in each molecule of a polymer.
[0019] Preferably, the proportion by weight of the component with
the higher MFI in the bi-component fiber is at most 50%, more
preferably at most 25%, even more preferably at most 10%, and in
particular at most 5%. In this case, the bi-component fiber is
especially preferably a core-sheath fiber, whereby the component
with the higher MFI forms the sheath.
[0020] Advantageously, the polymer of one of the two components has
been polymerized with a metallocene catalyst, and the polymer of
the other component has been polymerized with a Ziegler-Natta
catalyst and subjected to a subsequent visbreaking treatment. In
this case, the polymer is preferably a polyolefin, in particular
polypropylene, polyethylene or their copolymers or a mixture
thereof. The other polymer is preferably also polyolefin or a
polyolefin-copolymer. In this case, it is especially advantageous
when both polymers are composed of the same monomer or are at least
predominantly composed of the same monomer.
[0021] Metallocene catalysts are structurally uniform catalysts,
which contain transition metals coordinated by cyclopentadiene
ligands. Such catalysts are described in detail in U.S. Pat. No.
5,374,696 and U.S. Pat. No. 5,064,802. Reference is made expressly
to their disclosures which are hereby incorporated by reference.
The advantage of these catalysts is that the polymers that are
produced with these catalysts have a narrow molecular weight
distribution. The narrow molecular weight distribution results in
non-woven fabrics with high elongation at break. In this case, the
elongation at break is the expansion of fibers that occurs at the
peak tearing force, which is applied when tearing a strip of
non-woven fabric. Primarily, however, a narrow molecular weight
distribution results in an increase in the process safety in the
production of spunbond fabric. The frequency of spinning
disruptions, such as, for example, fiber fracture, is reduced. In
addition, a higher stretching of the fibers is possible, higher
spinning speeds can be reached, and the yarn counts that can be
achieved are lower. In this case, lower yarn counts mean a higher
fineness of fibers and/or of the yarns obtained from the
fibers.
[0022] Another advantage of the metallocene catalysts or the
polymers produced by means of metallocene catalysts is that the
residual content of the catalyst in the polymer is very low. The
residual content of the catalyst in the polymer represents a
contamination of the polymer and can result in the properties of
the polymer being changed in an undesirable way. Thus, for example,
staining can occur during the processing of the polymer.
[0023] One drawback of the metallocene catalysts is their slightly
higher price in comparison to the Ziegler-Natta catalysts. In
addition, thermal solidification of the fibers in the production of
non-woven fabric can be impeded when metallocene catalysts are
used. This may be the case if the possibility opened up by the use
of metallocene catalysts to increase the crystallinity and the
strength of the individual fibers by their higher level of
stretchability is used to a large extent.
[0024] Ziegler-Natta catalysts are heterogeneous mixed catalysts,
which contain organometallic compounds of main group elements and
transition metal compounds. As main group elements, in particular
elements of the first to third main groups are used. The transition
metal compounds contain in particular metals of the titanium group.
A host of variants of these catalysts exist. In terms of this
invention, the Ziegler-Natta catalysts are essentially defined by
their distinction compared to the metallocene catalysts.
[0025] The Ziegler-Natta catalysts are more economical than the
metallocene catalysts, however, polymers produced with the
Ziegler-Natta catalysts have a considerably broader molecular
weight distribution than polymers produced with metallocene
catalysts. To improve the stretchability of the fibers, which
serves in particular to increase the safety of the process, the
polymers produced with Ziegler-Natta catalysts are therefore
usually after-treated. This after-treatment is referred to as
"visbreaking." In the visbreaking treatment, polymer chains are
cleaved, by which the molecular weight of the individual molecules
is reduced, and the number of molecules is increased. In this case,
the width of the molecular weight distribution is also reduced. The
cleavage of the polymer chains is brought about by heat,
irradiation, the addition of peroxide, or by similar measures.
Examples of such visbreaking treatments are described in, i.a.,
U.S. Pat. No. 4,282,076 and U.S. Pat. No. 5,723,217.
[0026] By such a visbreaking treatment, however, neither the narrow
molecular weight distribution of the polymers produced with
metallocene catalysts nor the good stretchability of the fibers
obtained from these polymers can be achieved. Also, polymers that
have been produced with Ziegler-Natta catalysts have a higher
content of contaminants than polymers that have been produced with
metallocene catalysts. On the one hand, this depends on a
comparatively higher catalyst content being required in the
production of the polymer with a Ziegler-Natta catalyst, which
content produces a comparatively higher proportion of catalyst
residues in the polymer, and, on the other hand, this depends on
adjuvants, which are added within the scope of visbreaking
treatment, by which they represent an additional source for
contaminations of the finished polymer.
[0027] The advantage of polymers that are produced with use of
Ziegler-Natta catalysts with a subsequent visbreaking treatment is
primarily their favorable price and their high level of
availability on the market. Another advantage is the good thermal
connectivity of the fibers produced from these polymers.
[0028] It has now been shown, surprisingly enough, that the
advantageous selection of the polymers based on the catalysts that
were used in their production has the effect that a combination of
the advantages of the use of the respective catalyst types makes
possible the resulting bi-component fibers. Thus, it is possible to
drop the costs relative to the use of pure polymer fibers produced
by means of metallocene catalysts, but in this case at the same
time to implement the advantages of the use of metallocene
catalysts. In addition, in this case, a better connectivity of the
fibers in comparison to bi-components made from polymers that were
produced exclusively by using metallocene catalysts can be
achieved.
[0029] Preferably, the proportion by weight of the components,
whose polymer has been polymerized with a metallocene catalyst, is
at most 50% in the bi-component fiber, more preferably at most 25%,
even more preferably at most 10%, and in particular at most 5%. In
this case, the bi-component fiber especially preferably is a
core-sheath fiber, whereby the component whose polymer has been
polymerized with a metallocene catalyst forms the sheath.
[0030] Preferably, the first component has an additive for
influencing or improving properties.
[0031] Preferably, the proportion by weight of the additive of the
first component in the second component is at most 66.6%, more
preferably at most 50%, and in particular at most 33.3% of the
proportion by weight of the additive in the first component.
[0032] The advantage of the concentration of the additives in the
first component lies in the fact that it has been shown that the
amount of the required additive in the second component can be less
than in the usual equal distribution of the additive in the two
components, when the same or an improved action of the additive is
to be produced. It is also possible that the additive is present
only in the first component.
[0033] Additives in this sense are defined as admixtures that are
added to the polymer in the respective component in order to modify
and thus to improve the properties of the resulting fiber or of the
spunbond fabric obtained from the fiber.
[0034] Advantageously, the first component and the second component
in the fiber are arranged in such a way that in the cross-section
of the fiber, the first component surrounds the second
component.
[0035] Preferably, the proportion by weight of the first component
in the bi-component fiber is at most 50%, more preferably at most
25%, even more preferably at most 10%, and in particular at most
5%. In this case, the bi-component fiber is especially preferably a
core-sheath fiber, whereby the first component forms the
sheath.
[0036] The additives that are added at low concentrations to the
polymers in principle represent a contamination of the polymer with
respect to the fiber production. In the case of contaminations, in
principle there is always the risk that because of these
contaminations, the behavior of the components in the production of
fibers changes. Therefore, an unequal distribution of the additives
in the components of the bi-component fiber first involves the
risk, from the standpoint of one skilled in the art, the quality of
the bi-component fiber or the stability of the production process
deteriorates.
[0037] Moreover, from the standpoint of one skilled in the art, the
point is not usually that an additive is concentrated in a specific
zone of the fiber. This is due to the small thickness of the fibers
in question. As is the case with dyes or pigments, even in
additives, it likewise makes no obvious sense from the standpoint
of one skilled in the art to concentrate the latter in a specific
zone of the fiber. Thus, for example, in the case of a flame
retardant, in any case the entire fiber is to be affected by the
combustion processes. Also, UV irradiation will penetrate the
entire fiber. Surprisingly enough, it has nevertheless been shown
that in some cases, even especially advantageous results can be
achieved when the additive is not only reduced in the one component
but rather is completely omitted. One advantage of the
concentration of the additives in the first component is in any
case the cost savings because of the smaller amount of additive
required.
[0038] Advantageously, the additive is a primary or secondary
antioxidant, a UV absorber, a UV stabilizer, a flame retardant, an
antistatic agent, a lubricating agent, a metal deactivator, a
hydrophilizing agent, a hydrophobizing agent, an anti-fogging
additive, and/or a biocide. In this case, the following families of
substances and mixtures thereof are especially preferred: [0039]
Sterically inhibited phenols, aromatic secondary or tertiary
amines, aminophenols, aromatic nitro or nitroso compounds as
primary antioxidants. [0040] Organic phosphites or phosphonates,
thioethers, thioalcohols, thioesters, sulfides and
sulfur-containing organic acids, dithiocarbamates,
thiodipropionates, aminopyrazoles, metal-containing chelates,
mercaptobenzimidazoles as secondary antioxidants. [0041]
Hydroxybenzophenones, cinnamates, oxalanilides, salicylates, 1,3
benzenediol-monobenzoates, benzotriazoles, triazines,
benzophenones, as well as UV-absorbing pigments such as titanium
dioxide or carbon black as a UV absorber. [0042] Metal-containing
complexes of organic sulfur compounds or phosphorus compounds,
sterically hindered amines (HALS) as UV stabilizers. [0043] Metal
hydroxides, borates, organic bromine- or chlorine-containing
compounds, organic phosphorus compounds, antimony trioxide,
melamine, melamine cyanurate, expanded graphite or other
intumescence systems as flame retardants. [0044] Quaternary
ammonium salts, alkyl sulfonates, alkyl sulfates, alkyl phosphates,
dithiocarbamates, alkaline(-earth) metal carboxylates, polyethylene
glycols, as well as their esters and ethers, fatty acid esters,
ethoxylates, mono- and diglycerides, and ethanolamines as
antistatic agents. [0045] Fatty alcohols, esters of fatty alcohols,
fatty acids, fatty acid esters, dicarboxylic acid esters, fatty
acid amides, metal salts of fatty acids, polyolefin waxes, natural
or synthetic paraffins, and their derivatives, fluoropolymers and
fluoroligomers, anti-blocking agents such as silicic acids,
silicones, silicates, calcium carbonate, etc., as lubricating
agents. [0046] Amides of mono- and dicarboxylic acids, and their
derivatives, cyclic amides, hydrazones, and bishydrazones,
hydrazides, hydrazines, melamine and its derivatives,
benzotriazoles, aminotriazoles, sterically inhibited phenols in
connection with complexing metal compounds, benzyl phosphonates,
pyridithiols, thiobisphenol esters as metal deactivators. [0047]
Polyglycols, ethoxylates, fluoropolymers and fluoroligomers, montan
waxes, in particular stearates, as hydrophilizing, hydrophobizing,
or anti-fogging agents. [0048] 10,10'-Oxybisphenoxarsine (OBPA),
N-(trihalo-methylthiol)phthalimide, tributyltin oxide, zinc
dimethyl dithiocarbamate, diphenylantimony-2-ethyl hexanoate,
copper-8-hydroxyquinoline, isothiazolone, silver and silver salts
as biocides.
[0049] For example, when executing a burning test according to EN
13501-1, it can be noted that in the above-mentioned distribution
of the additive in the components, a smaller amount of the additive
overall, in this example a flame retardant, is sufficient to
provide a positive test result than when the flame retardant is
uniformly distributed in the fiber. In this test, within fractions
of a second, the entire fiber is enveloped by the flame, so the
advantageous effect cannot readily be attributed to a kind of
shielding action of the sheath area of the fiber.
[0050] Advantageously, the first polymer and/or the second polymer
is/are a polyolefin or a polyolefin-copolymer, preferably a polymer
and/or copolymer of ethylene, propylene, butylene, hexene or
octene, and/or a mixture and/or a blend thereof. It has been shown
that these polymers are especially well suited to produce therefrom
the bi-component fibers according to the invention. In this
connection, a copolymer is defined as a polymer that was produced
from at least two different types of monomers, whereby the
proportion by weight of the monomer, which is decisive for the
naming of the copolymer, is at least 50%.
[0051] Preferably, the bi-component fiber is a core-sheath fiber,
whereby the proportion by weight of the core is 50% to 98%,
preferably 60% to 95%, especially preferably 70% to 95%, and quite
especially preferably 80% to 90%. It has been shown that the
advantages of the bi-component fiber according to the invention,
when the latter is a core-sheath fiber, occur particularly in the
case of these advantageous proportions by weight of the core.
[0052] If the bi-component fiber is a side-by-side fiber,
segmented-pie fiber or islands-in-the-sea fiber, the mass ratio of
the two components lies in the range of 10:90 up to 90:10,
preferably in the range of 70:30 up to 30:70, and especially
preferably in the range of 60:40 up to 40:60. In the case of these
fiber types, it has been shown that the advantages of the
bi-component fibers according to the invention can be achieved
especially readily for the cited component ratios.
[0053] In the case of another preferred embodiment, the
bi-component fiber is a multilobal fiber, in particular a
tetralobal or trilobal fiber. As a function of their
cross-sectional geometry, these fibers offer a higher specific
surface area than comparable fibers with circular cross-sections.
In connection with the latter, the advantages of the fibers
according to the invention can be used especially efficiently, in
particular when the different properties of the components, which
are to be optimized by the bi-component fibers according to the
invention, are properties that relate to the surface area of the
fibers.
[0054] Advantageously, the diameter of the bi-component fiber is
between 1 .mu.m and 50 .mu.m, preferably between 5 .mu.m and 30
.mu.m, and especially preferably between 8 .mu.m and 20 .mu.m. It
has been shown that especially in the case of fiber diameters that
lie in these advantageous ranges, the combination of two components
in a bi-component fiber results particularly in synergistic
effects.
[0055] In addition, the invention relates to a spunbond fabric with
bi-component fibers according to the invention. Two properties that
play a special role in spunbond fabrics are the specific tearing
force of the spunbond fabric as well as the specific nail tear
resistance of the spunbond fabric. In this case, a desirable high
specific tearing force is achieved by fibers with high
strength.
[0056] In this sense, good connectivity is defined as the
movability of the fibers in the spunbond fabric being able to be
set defined as much as possible in the connecting of the fibers
during the production of a spunbond fabric. The targeted setting of
the movability of fibers in the non-woven fabric, which depends on
the strength of the connecting of the fibers among themselves, is
the requirement for the production of a spunbond fabric with high
specific tensile strength and at the same time high specific nail
tear resistance.
[0057] In practice, the problem may exist that suitable fibers with
high strength have a poor connectivity and fibers with a good
connectivity have only a low level of strength. Therefore,
especially in the case of the production of a spunbond fabric,
which is to have both a high specific tearing force and a high
specific nail tear resistance, the use of a bi-component fiber is
useful. In this case, the bi-component fibers according to the
invention are particularly suitable to make possible a high
specific tearing force and a high specific nail tear resistance of
a spunbond fabric, since especially the bi-component fibers
according to the invention can be optimized with respect to a
combination of good connectivity and high strength.
[0058] Such a non-woven fabric produced from the fibers according
to the invention is suitable for numerous applications, for example
in medicine, in the field of hygiene, in the automobile industry,
in the field of clothing, in home and industrial textiles, as well
as in particular in the construction industry and in agriculture.
In addition, possible applications comprise the use in filters and
membranes, battery separators and as support non-woven fabrics for
laminates and as carriers for coatings of all types.
[0059] Advantageously, the weight per unit of area of the spunbond
fabric is between 1 g/m.sup.2 and 300 g/m.sup.2, preferably between
5 g/m.sup.2 and 200 g/m.sup.2, and especially preferably between 8
g/m.sup.2 and 200 g/m.sup.2. It has been shown that in the case of
weights per unit of area, which lie in these advantageous ranges,
the use of a bi-component fiber with high strength and at the same
time good connectivity according to the invention particularly
results in a combination that consists of high specific tearing
force and at the same time high specific nail tear resistance of
the non-woven fabric produced from these fibers.
[0060] Advantageously, the specific tearing force of the spunbond
fabric is at least 1.8 N/g5 cm in the machine direction and/or at
least 1.3 N/g5 cm in the transverse direction, preferably 2.0 N/g5
cm in the machine direction and/or at least 1.5 N/g5 cm in the
transverse direction, preferably at least 2.2 N/g5 cm in the
machine direction, and/or at least 2.0 N/g5 cm in the transverse
direction, and especially preferably at least 2.4 N/g5 cm in the
machine direction, and/or at least 1.9 N/g5 cm in the transverse
direction. In this case, machine direction refers to the direction
in which the spunbond fabric has been transported during its
production in the machine, i.e., routinely the longitudinal
direction of a spunbond fabric web. Transverse direction refers to
the direction that lies at a right angle to the latter, in which
the spunbond fabric expands in a flat manner, i.e., routinely the
width of a spunbond fabric web. In this case, the specific tearing
force is measured according to EN 12311-1.
[0061] It has been shown that achieving these advantageous minimum
values for the specific tearing force of the spunbond fabric should
be the goal in any case when bi-component fibers according to the
invention are used for the production of the spunbond fabric. The
bi-component fibers according to the invention allow these
advantageous minimum values to be achieved for the specific tearing
force without the specific nail tear resistance dropping
disproportionately thereby.
[0062] Advantageously, the specific nail tear resistance of the
spunbond fabric is at least 1.0 N/g in the machine direction and/or
at least 1.2 N/g in the transverse direction, preferably at least
1.4 N/g in the machine direction and/or at least 1.5 N/g in the
transverse direction, preferably at least 1.6 N/g in the machine
direction, and/or at least 2.16 N/g cm in the transverse direction,
and especially preferably at least 1.8 N/g in the machine
direction, and/or at least 2.1 N/g in the transverse direction.
[0063] The specific nail tear resistance is in this case the
maximum force that occurs when tearing a strip of non-woven fabric
when the strip of non-woven fabric already has given damage, namely
a nail thrust through the non-woven fabric. The specific nail tear
resistance is measured according to EN 12310-1. It has been shown
that the above-mentioned minimum values for the specific nail tear
resistance of the spunbond fabric can be sought without the
specific tearing force of the spunbond fabric dropping
disproportionately, when bi-component fibers according to the
invention are optimized accordingly with respect to their
connectivity and strength. In particular, in this case, it is also
possible to produce a combination of the above-mentioned specific
advantageous nail tear resistance and the previously-mentioned,
advantageous specific minimum tearing forces.
[0064] The combination of these two advantageous minimum parameters
results in a spunbond fabric, which is suitable for a host of
applications with respect to its mechanical properties. Such a
spunbond fabric can be readily used, for example, in the
construction field, where frequently a fastening of the spunbond
fabric webs by nailing, stapling, or screwing must be possible. In
this case, the spunbond fabric must not tear away or tear off when
it is fastened to, for example, a roof Also, use of these
advantageous spunbond fabrics as geotextiles is readily possible.
Geotextiles must in any case have a high tolerance for selective
damage, as can be caused by, for example, sharp stones.
[0065] In practice, a high specific nail-tear-out strength often
accompanies a good surface feel. The softness and the textile grip
of such spunbond fabrics therefore also open up applications, e.g.,
applications in the field of hygiene or medicine. The cause of the
good surface feel is the high movability of individual fibers,
which routinely accompanies the occurrence of high nail tear
resistance. In practice, fibers that behave in this manner
routinely also have haptic properties that are perceived as soft
and comfortable. The fiber segment movability makes it possible for
fibers to "gather" in or around the nail during the movement of the
nail through the non-woven fabric by avoiding the nail as it moves
through the non-woven fabric and not immediately tearing. This
leads to a zone of increased fiber density, i.e., a zone of
increased strength, around the nail.
[0066] It is understood that the invention is also extended to
threads or objects produced therefrom, which have one or a large
number of bi-component fibers of the above-mentioned type. In
particular, the invention also relates to a spunbond fabric that is
produced from bi-component fibers according to the invention. A
spunbond fabric according to the invention is a structure, in
particular a textile pattern, made from bi-component fibers
according to the invention, in particular continuous fibers that
have been joined in any way to form a non-woven fabric and have
been connected with one another in any way.
[0067] The invention also relates to a method for the production of
bi-component fibers according to the invention and a method for the
production of a spunbond fabric from the bi-component fibers
according to the invention.
[0068] Advantageously, in this case, the two components of the
bi-component fiber are melted separately. The polymer melts thus
produced form the starting material for the fibers. It is
advantageous to combine the melt flows thus produced only once they
are in a spinning plate. In such a spinning plate, the melt flows
are extruded by spinning nozzles to form bi-component fibers,
Advantageously, in this case, the spinning nozzles have a hole
diameter of 0.1 mm to 10 mm, preferably a hole diameter of 0.2 mm
to 5 mm, and especially preferably a hole diameter of 0.5 mm to 3
mm. Spinning nozzles, whose hole diameter lies in the
above-mentioned preferred ranges, have proven especially suitable
for the production of bi-component fibers.
[0069] It is advantageous to stretch the extruded fibers
mechanically after their extrusion. Preferably, in this case, the
fibers are drawn off over galettes. Galettes are special rollers
that are used in the production of synthetic threads and fibers and
serve in the transporting and/or stretching and/or heat treatment
of the fibers or threads.
[0070] Advantageously, in this case, the cooling rate of the fibers
can be regulated by the temperature of the galettes. By the defined
cooling rate, in particular during the stretching of the fibers,
their mechanical properties can be further improved.
[0071] In a likewise advantageous way, a stretching of the fibers
by an air flow guided along the fiber is also possible. Preferably,
in this case, the cooling rate of the fibers is regulated by the
temperature of the air flow and/or the amount of air.
[0072] For the production of a spunbond fabric, it is advantageous
to swirl the fibers, which in this connection are also referred to
as filaments, after they are cooled and stretched. The fibers thus
acquire a random arrangement. In this case, parts of the fibers are
reoriented from the machine direction into the transverse
direction, so that an overall more isotropic non-woven fabric can
be obtained. Then, the fibers can be placed on a filter belt.
[0073] The layer of fibers thus produced can then be preferably
thermally solidified. During solidification, the individual fibers
are connected to one another, by which the actual non-woven fabric
is produced. The thermal solidification can in this case be carried
out by flowing through with hot air or water vapor; in an
especially advantageous way, it is carried out by calendering.
Calendering is defined as solidification with use of hot or heated
rollers. In an advantageous way, the calendering can be carried out
with a smooth roller and a sculptured roller. In this case, the
sculptured roller is preferably configured in such a way that a
proportional pressing surface of at least 5% and at most 25%,
preferably at least 8% and at most 20%, and especially preferably
at least 12% and at most 20%, is produced because of the engraving
of the rollers. As a result, the connecting of the fibers among
themselves and thus the movability of the fibers can be
specifically influenced.
[0074] The temperature of the rollers in this case is preferably at
most 70.degree. C., preferably at most 50.degree. C. less than the
temperature of the melting point of the component with the lower
melting point. A good connecting of the fibers is ensured by these
minimum temperatures of the rollers. In this case, the pressing
pressure of the rollers in the roll gap is advantageously 10 N/mm
to 250 N/mm, preferably 25 N/mm to 200 N/mm, and especially
preferably 50 N/mm to 150 N/mm. In particular, in combination with
the above-mentioned advantageous temperatures, it is useful to set
the pressing pressure within the above-mentioned advantageous
ranges. It has been shown that the connections between the fibers
that are produced when using these parameter combinations result in
a spunbond fabric with good mechanical properties when the
bi-component fibers according to the invention are used.
[0075] As an alternative, the solidification of the fiber layer can
also be carried out mechanically. In this case, the non-woven
fabric, for example, can be needled or solidified by means of water
jets. Another possible advantageous alternative is the chemical
solidification of the fiber layer. In this case, a binder is
applied to the fiber layer, for example by impregnation or
spraying. This binder is hardened, by which the fibers are
connected to the spunbond fabric. The hardening of the binder can
take place by, for example, tempering, photo-induced or
moisture-induced cross-linking, cooling, evaporation of a solvent,
or similar measures.
[0076] It is expressly pointed out that the features indicated in
the above-mentioned separate paragraphs in each case can be
combined in combination with the basic ideas of this invention
without features from others of the above-mentioned paragraphs
being absolutely necessary for implementing the invention.
[0077] In addition, it is expressly pointed out that all intervals
mentioned above and listed below contain all intermediate intervals
and also individual values contained therein, and these
intermediate intervals and individual values can be regarded as
essential to the invention even when these intermediate intervals
or individual values are not actually indicated in detail.
[0078] Other features, advantages and possible applications of this
invention follow from the subsequent description of embodiments
based on the drawing and the drawing itself. In this case, all
features that are described and/or depicted graphically form the
subject of this invention by themselves or in any combination,
regardless of how they are combined in the claims or how they are
referenced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0079] FIG. 1 is a cross-sectional view of an embodiment of a
bi-component fiber according to the invention as a core-sheath
fiber,
[0080] FIG. 2 is a cross-sectional view of an embodiment of a
bi-component fiber according to the invention as a core-sheath
fiber with a thin sheath,
[0081] FIG. 3 is a cross-sectional view of another embodiment of a
bi-component fiber according to the invention as a core-sheath
fiber with an eccentrically arranged core,
[0082] FIG. 4 is a cross-sectional view of another embodiment of a
trilobal bi-component fiber according to the invention as a
core-sheath fiber,
[0083] FIG. 5 is a cross-sectional view of another embodiment of a
bi-component fiber according to the invention as a side-by-side
fiber,
[0084] FIG. 6 is a cross-sectional view of another embodiment of a
bi-component fiber according to the invention as a side-by-side
fiber with a small proportion of the second component,
[0085] FIG. 7 is cross-sectional views at various spots along
another embodiment of a bi-component fiber as a mixed type that
consists of core-sheath fibers and side-by-side fibers,
[0086] FIG. 8 is a cross-sectional view of another embodiment of a
bi-component fiber according to the invention as a side-by-side
fiber,
[0087] FIG. 9 shows cross-sections at various spots along another
embodiment of a bi-component fiber according to the invention as a
mixed type of a side-by-side fiber and a core-sheath fiber,
[0088] FIG. 10 is a cross-sectional view of another embodiment of a
trilobal bi-component fiber according to the invention as a
side-by-side fiber,
[0089] FIG. 11 is a cross-sectional view of another embodiment of a
trilobal bi-component fiber according to the invention as a
side-by-side fiber,
[0090] FIG. 12 is a cross-sectional view of another embodiment of a
trilobal bi-component fiber according to the invention as a
side-by-side fiber with an alternative arrangement of the
components,
[0091] FIG. 13 is a cross-sectional view of another embodiment of a
tetralobal bi-component fiber according to the invention as a
side-by-side fiber with a component arrangement similar to the
fiber depicted in FIG. 12,
[0092] FIG. 14 is a cross-sectional view of another embodiment of a
bi-component fiber according to the invention as a segmented-pie
fiber,
[0093] FIG. 15 is a cross-sectional view of another embodiment of a
bi-component fiber according to the invention as an
island-in-the-sea fiber,
[0094] FIG. 16 is a cross-sectional view of another embodiment of a
bi-component fiber according to the invention with a strip-like
arrangement of the components, and
[0095] FIG. 17 shows a portion of a spunbond fabric according to
the invention by way of example.
DETAILED DESCRIPTION OF THE INVENTION
[0096] FIGS. 1 to 16 show cross-sectional views of bi-component
fibers 1 according to the invention by way of example. The depicted
bi-component fibers 1, in each case, have a first component 2 and a
second component 3. In the core-sheath fibers depicted in FIGS. 1
and 4, in this case, the first component 2 surrounds the second
component 3 and thus forms the outer surface of the fiber. In this
case, the bi-component fibers 1 depicted in FIGS. 1 to 3 have an at
least approximately circular or round geometry in cross-section.
The bi-component fiber depicted in FIG. 4 shows, however, a
trilobal cross-section. Such trilobal cross-sections, like other
multilobal cross-sections as well, have the effect that the fiber
has a larger outer surface in relation to its mass than is the case
with fibers with a circular cross section. In the case of
"core-sheath fibers," in which the proportion of the components
forming the sheath is very small, for example approximately 2%, but
certainly even in "core-sheath fibers" with a higher sheath
proportion, it may occur that the sheath has defects. This means
that the sheath does not completely surround the core but rather is
broken at several spots, so that the core at these spots also forms
the outer surface of the fiber. Also, such fibers are "core-sheath
fibers." In particular, in the case of such fibers, the component
that forms the broken sheath constitutes the outer surface of the
fiber in terms of this invention.
[0097] FIGS. 5, 6, 8 and 10 to 13 show bi-component fibers that are
embodied as side-by-side fibers. These side-by-side fibers are
characterized in that both the first component 2 and the second
component 3 form a portion of the outer surface of the bi-component
fiber 1. Also, in the case of side-by-side fibers, circular or at
least approximately circular cross-sections, as they are depicted
in FIGS. 5, 6 and 8, are also possible, such as multilobal cross
sections, as they are depicted in FIGS. 10 to 13. Depending on
which fiber properties or nonwoven fabric properties are to be
achieved, the first component 2 and the second component 3 can be
combined with one another in different ratios and in different
spatial arrangements. Thus, for example, as is shown in FIG. 8, a
component--the second component 3 in the example that is shown--can
be arranged so that it forms only a small proportion of the outer
surface of the bi-component fiber 1 relative to its proportion by
weight. Also, as is depicted in FIGS. 12 and 13, a component, the
first component 2 in the examples shown, can be arranged at
especially exposed spots of the bi-component fiber 1 in the case of
a multilobal bi-component fiber 1. In FIGS. 12 and 13, the first
component 2 is arranged at the tips of the multilobal cross-section
of the bi-component fiber 1.
[0098] The bi-component fiber 1 that is depicted in FIG. 14 is
embodied as a segmented-pie fiber. In this respect, this fiber
structure exhibits a similarity to the side-by-side fiber
structures to the extent that both the first component 2 and the
second component 3 form a portion of the outer surface of the
bi-component fiber 1. The same applies to the bi-component fiber 1
mentioned there for the structure depicted in FIG. 16, in which the
first component 2 and the second component 3 alternate in
cross-section in a layer structure. In contrast to the "classical"
side-by-side structures, the structures shown in FIGS. 14 and 16
have in common the fact, however, that in each case they have a
host of areas that are formed from the first component 2 or the
second component 3.
[0099] However, the bi-component fiber 1 shown in FIG. 15 with its
islands-in-the-sea structure can be regarded as a variation on a
core-sheath fiber, in which a host of cores from the second
component 3 are present. The individual cores from the second
component 3 are surrounded by a common sheath that consists of the
first component 2.
[0100] In addition, mixed forms between core-sheath fibers and
side-by-side fibers are possible, as they are depicted by way of
example in FIGS. 7 and 9. The bi-component fiber 1 depicted in FIG.
7 has partial cross-sections along the fibers in which the first
component 2 surrounds the second component 3 similar to a
core-sheath fiber and forms by itself the outer surface of the
bi-component fiber 1. At other spots along the fiber, the second
component 3 also forms a portion of the outer surface of the
bi-component fiber 1. The first component 2 does not completely
surround the second component 3 in cross-section. This also applies
for the bi-component fiber 1 depicted in FIG. 9; the latter has
only one other alternative geometry in comparison to the
bi-component fiber 1 depicted in FIG. 7. Also, in terms of this
application, such mixed forms are also referred to as core-sheath
fibers as long as the first component forms more than 50% of the
outer surface of the fiber.
[0101] In FIG. 17, it is shown how a host of bi-component fibers 1,
by way of example, form a spunbond fabric 4. In this case, the
spunbond fabric forms a web with a transverse direction X, a
thickness direction Y, and a longitudinal direction Z, which is
also referred to as the machine direction.
[0102] The specific tearing forces of the spunbond fabric 4
according to the following examples were measured according to the
standard EN 12311-1, the specific nail tear resistance according to
standard EN 12310-1. The MFIs were measured according to ISO 1133
(2.16 kg at 230.degree. C.). The bi-component fibers 1 are
core-sheath fibers in the following examples, with a sheath that
comprises the first component 2 and a core that formed of the
second component 3.
[0103] A spunbond fabric 4, by way of example, was produced from
bi-component fibers 1, which were thermally solidified by means of
a calender. The weight per unit of area of the spunbond fabric 4
that is produced is 70 g/m.sup.2. The bi-component fibers 1 have
polypropylene with a melting point of 140.degree. C. in the sheath
as a first polymer and polypropylene with a melting point of
148.degree. C. in the core as a second polymer. The proportion by
weight of the core in the bi-component fiber 1 is 90%. The specific
tearing forces of the spunbond fabric 4 that are achieved are 2.41
N/g5 cm in the machine direction Z and 1.80 N/g 5 cm in the
transverse direction X. The specific nail tear resistance are 1.52
N/g in the machine direction Z and 1.80 N/g in the transverse
direction X.
[0104] Another spunbond fabric 4, by way of example, was produced
from bi-component fibers 1, which were also thermally solidified by
means of a calender. The weight per unit of area of the spunbond
fabric 4 that was produced is 70 g/m.sup.2. The bi-component fibers
1 have polypropylene with a melting point of 148.degree. C. in the
sheath as a first polymer and polypropylene with a melting point of
151.degree. C. in the core as a second polymer. The proportion by
weight of the core in the bi-component fiber 1 is 60%. The specific
tearing forces of the spunbond fabric 4 that are achieved are 2.61
N/g5 cm in the machine direction Z and 1.95 N/g5 cm in the
transverse direction X. The specific nail tear resistances are 1.59
N/g in the machine direction Z and 1.90 N/g in the transverse
direction X.
[0105] Another spunbond fabric 4 by way of example was produced
from bi-component fibers 1, which were also thermally solidified by
means of a calender. The weight per unit of area of the spunbond
fabric 4 that was produced is 70 g/m.sup.2. The bi-component fibers
1 have a polypropylene-based random copolymer with a proportion of
ethylene of approximately 5% with a melting point of 141.degree. C.
in the sheath as a first polymer and polypropylene with a melting
point of 145.degree. C. in the core as a second polymer. The
proportion by weight of the core in the bi-component fiber 1 is
70%. The specific tearing forces of the spunbond fabric 4 that are
achieved are 2.44 N/g5 cm in the machine direction Z and 1.90 N/g5
cm in the transverse direction X. The specific nail tear
resistances are 1.49 N/g in the machine direction Z and 1.79 N/g in
the transverse direction X.
[0106] Another spunbond fabric 4, by way of example, was produced
from bi-component fibers 1, which were also thermally solidified by
means of a calender. The weight per unit of area of the spunbond
fabric 4 that was produced is 70 g/m.sup.2. The bi-component fibers
1 have polypropylene with a melting point of 140.degree. C. in the
sheath as a first polymer and polypropylene with a melting point of
148.degree. C. in the core as a second polymer. The proportion by
weight of the core in the bi-component fiber 1 is 93%. The specific
tearing forces of the spunbond fabric 4 that are achieved are 2.21
N/g5 cm in the machine direction Z and 1.65 N/g5 cm in the
transverse direction X. The specific nail tear resistances are 1.62
N/g in the machine direction Z and 1.93 N/g in the transverse
direction X.
* * * * *