U.S. patent application number 14/760646 was filed with the patent office on 2015-12-10 for batt comprising crimped bi- or multi-component fibres.
This patent application is currently assigned to PEGAS NONWOVENS s.r.o.. The applicant listed for this patent is PEGAS NONWOVENS s.r.o.. Invention is credited to Pavlina KASPARKOVA, Frantisek KLASKA, Jaroslav KOHUT, Zdenek MECL.
Application Number | 20150354112 14/760646 |
Document ID | / |
Family ID | 50156517 |
Filed Date | 2015-12-10 |
United States Patent
Application |
20150354112 |
Kind Code |
A1 |
KOHUT; Jaroslav ; et
al. |
December 10, 2015 |
BATT COMPRISING CRIMPED BI- OR MULTI-COMPONENT FIBRES
Abstract
A had comprising crimped bi- or multicomponent fibres consisting
of at least two sections, which comprise a polymer or polymer blend
as a predominant component and which are arranged across the
cross-section of the fiber to promote crimping of the fibre during
the setting process and which predominant components differ in. the
crystallisation beat (dHc). The difference in the crystallisation
heat (dHc) is in the range from 30 J/g to 5 J/g, and the
predominant components differ in at least one of the other
parameters selected from the group of melt flow index, degree of
polydispersion and flexural modulus, while the relative difference
of the predominant components is: for the flow index in the range
from 100 g/10 min to 5 g/10 min and/or for the degree of
polydispersion less than 1, but above 0.3, and/or for the flexural
modulus in the range from 300 MPa to 50 MPa; where the relative
difference in the melt flow index is not greater than 100 g/10 min,
the degree of polydispersity is less than 1, the crystallisation
heat is not greater than 300 Mpa. The fibres have the degree of
crimping at least 5 crimps per 20 mm of fibre.
Inventors: |
KOHUT; Jaroslav; (Znojmo,
CZ) ; MECL; Zdenek; (Nov Saldorf-Sedlesovice, CZ)
; KLASKA; Frantisek; (Slavkov u Brna, CZ) ;
KASPARKOVA; Pavlina; (Znojmo, CZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PEGAS NONWOVENS s.r.o. |
Znojmo |
|
CZ |
|
|
Assignee: |
PEGAS NONWOVENS s.r.o.
Znojmo
CZ
|
Family ID: |
50156517 |
Appl. No.: |
14/760646 |
Filed: |
January 14, 2014 |
PCT Filed: |
January 14, 2014 |
PCT NO: |
PCT/CZ2014/000005 |
371 Date: |
July 13, 2015 |
Current U.S.
Class: |
442/353 ;
264/103; 428/370 |
Current CPC
Class: |
Y10T 442/629 20150401;
D01F 8/06 20130101; D10B 2509/026 20130101; D04H 3/007 20130101;
Y10T 428/2924 20150115; D04H 3/16 20130101; D01D 5/30 20130101;
D04H 3/02 20130101; D04H 3/147 20130101; D04H 3/018 20130101; D01D
5/22 20130101; D10B 2321/022 20130101 |
International
Class: |
D04H 3/018 20060101
D04H003/018; D04H 3/02 20060101 D04H003/02; D01F 8/06 20060101
D01F008/06; D04H 3/007 20060101 D04H003/007; D01D 5/22 20060101
D01D005/22 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 2013 |
CZ |
PV 2013-24 |
Claims
1. A batt comprising crimped bi- or multicomponent fibres
consisting of at least two sections, which comprise a polymer or
polymer blend as a predominant component and which are arranged
across the cross-section of the fiber in a way suitable to promote
crimping of the fibre during the setting process and which
predominant components differ in the crystallisation heat (dHc),
wherein the difference in the crystallisation heat (dHc) is in the
range from 30 J/g to 10 J/g, and that the predominant components
differ in at least one of the other parameters selected from the
group of melt flow index, degree of polydispersion and flexural
modulus, while the relative difference of the predominant
components is: for the flow index in the range from 100 g/10 min to
5 g/10 min and/or for the degree of polydispersion less than 1, but
above 0.3, and/or for the flexural modulus in the range from 300
MPa to 50 MPa; where the relative difference in the melt flow index
is not greater than 100 g/10 min, in the degree of polydispersity
is less than 1, in flexural modulus is not greater than 300 MPa;
and where said fibres have the degree of crimping at least 5 crimps
per 20 mm of fibre.
2. A batt comprising crimped fibres according to claim 1, wherein
the relative differentiation of the predominant components in the
melt flow index is in the range of 80 g/10 min.
3. A batt comprising crimped fibres according to claim 1, wherein
the relative differentiation of the predominant components in the
degree of polydispersion is in the range of 1 to 0.5.
4. (canceled)
5. A batt comprising crimped fibres according to claim 1, wherein
the relative differentiation of the predominant components in the
flexural modulus is in the range of 250 MPa to 80 MPa.
6. A batt comprising crimped fibres according to claim 1, wherein
the fibres are bicomponent fibres of the side-by-side type.
7. A batt comprising crimped fibres according to claim 6, wherein
both predominant components of the bicomponent fibres are a
propylene homopolymer.
8. A batt comprising crimped fibres according to claim 1, wherein
said predominant components are arranged across the cross-section
of the fibres, centrally asymmetrically and/or axially
asymmetrically relative to a number of axes passing through the
centre of the fibre's cross-section, which evens the number of the
polymer sections in the fibre.
9. A batt according to claim 1, wherein the fibers comprise an
additive, wherein the additive is present in the components such
that it does not affect the crimping of the fiber to a significant
degree.
10. A nonwoven textile characterised in that it comprises the batt
according to claim 1.
11. The nonwoven textile according to claim 10 wherein the nonwoven
textile is of a spunmelt type.
12. A method of producing a batt comprising multicomponent fibres,
wherein the method comprises the following steps: i. preparing at
least two materials comprising a polymer or polymer blend as a
predominant component the materials being suitable for the
formation of fibres; ii. then forming multicomponent fibres from
the prepared materials under a spinneret, namely multicomponent
fibres comprising said materials arranged in sections, which are
arranged across the cross-section of the fiber in a way suitable to
promote crimping of the fibre during the setting process, and
cooling and attenuating the fibres by cooling and attenuating air;
and iii. forming a batt from said multicomponent fibres; wherein
said predominant components in sections are selected such that they
differ in the heat of crystallisation (dHc) in the range from 30
J/g to 10 J/g, and that they differ in at least one other parameter
selected from the group of melt flow index, degree of
polydispersion and flexural modulus, where the relative
differentiation of the polymer components is: for the flow index in
the range from 100 g/10 min to 5 g/10 min and/or for the degree of
polydispersion in the range from 1 to 0.3, and/or for the flexural
modulus in the in the range from 300 MPa to 50 MPa; wherein the
relative difference in the melt flow index is no greater than 100
g/10 min, in the degree of polydispersity is no greater than 1, in
the flexural modulus is no greater than 300 MPa; and wherein said
fibres have the degree of crimping at least 5 crimps per 20 mm of
fibre.
13. The method according to claim 12, wherein said sections with
predominant components are arranged across the cross-section of the
fibre centrally asymmetricaly and/or axially asymmetricaly relative
to a number of axes passing through the centre of the cross-section
of a fibre, which evens the number of present sections in the
fibre.
14. The method according to claim 12, wherein said multicomponent
fibres are bicomponent fibres of the side-by-side type.
15. The method according to claim 12, wherein said polymer sections
contain as their predominant component a polypropylene
homopolymer.
16. A batt comprising crimped fibres according to claim 1, wherein
the difference in the crystallisation heat (dHc) is in the range
from 30 J/g to 20 J/g.
17. A batt comprising crimped fibres according to claim 2, wherein
the relative differentiation of the predominant components in the
melt flow index is in the range of 60 g/10 min to 10 g/10 min.
18. A batt comprising crimped fibres according to claim 3, wherein
the relative differentiation of the predominant components in the
degree of polydispersion is in the range of 1 to 0.7.
19. A batt comprising crimped fibres according to claim 5, wherein
the relative differentiation of the predominant components in the
flexural modulus is in the range of 200 MPa to 80 MPa.
20. The method according to claim 12 wherein predominant components
in sections are selected such that they differ in the heat of
crystallisation (dHc) in the range from 30 J/g to 20 J/g.
Description
TECHNICAL FIELD
[0001] The invention relates to a batt comprising crimped bi- or
multicomponent fibres consisting of at least two materials, which
comprise a polymer as a predominant component and which are
arranged across the cross-section of the fiber in a way suitable to
promote crimping of the fibre during the setting process and which
predominant polymer components differ in the crystallisation heat
(dHc). The here-described batt type is intended especially for the
production of nonwoven textiles that are to be used primarily for
applications in the hygiene industry.
BACKGROUND ART
[0002] The bulkiness of nonwoven textiles may be of significance
for a number of reasons. Nonwoven textiles are often used as a part
of hygiene products, where the bulkiness of the material may be
used both for reasons of functionality (for example as a part of
the loop part of the fastening system consisting of hooks and loops
or, for example, for the improvement in the distribution of liquids
in the core of absorptive products) as well as for sensory
reasons--the bulkiness of the material, apart from other things,
gives softness and may be positively accepted in contact with the
skin. In certain cases, nonwoven textiles may be used as a part of
cleaning products such as for example wipes and dusters. The
improvement in bulkiness of such nonwoven textiles may also improve
their effectiveness as a cleaning element.
[0003] In a number of cases, effort was intentionally expended into
creating or modifying certain properties of nonwoven textile
materials with the objective of their improvement. These efforts
consisted of the selection and/or modification of various chemical
compositions of fibres, the basis weight, the fibre layering
method, the density of fibres, the extrusion of various patterns,
the use of various types of bonding, etc.
[0004] The bulkiness of a nonwoven textile is directly related to
the properties of the fibres that form it. Homogenous continuous
fibres are typical for spunmelt nonwoven textiles. Bulkiness can
subsequently be increased by the use of bonding methods. One method
consists of the use of such thermal bonding methods, which retain
the maximum share of loose fibre segments between the individual
bonding points that are used to achieve the required strength of
the final material. Another method consists of exposing the
nonwoven textile, after calender bonding, to a jet of water
(hydroenhancing or hydroentanglement) in order to fluff up the
fibres and increase their specific thickness.
[0005] Another method consists of producing nonwoven textiles from
"bicomponent" polymer fibres, includes steps where these fibres are
created under the spinneret, laid to create a batt and subsequently
bonded using an embossing calender selected for the purpose of
achieving a certain patterned effect. Such bicomponent fibres can
be produced using spinnerets equipped with two adjacent sections,
where the first polymer is delivered through the first one and the
second polymer is delivered through the second in order to create a
fibre having one part of the cross-section formed by the first
polymer and the second part of the cross-section formed by the
second polymer (hence the term "bicomponent"). The respective
polymers can be selected to have differing characteristic
properties, which enable, in the side-by-side or asymmetrical
core/sheath geometry combinations, the curling of bicomponent
fibres during the spinning process as they are cooled and drawn
from under the spinneret. Various documents are known to exist that
deal with the application of individual differences for achieving
the curling of fibres. For example the European patent EP0685579
from Kimberly Clark describes the combination of polypropylene and
polyethylene. Another European patent EP1129247 from the same
company describes the combination of different polypropylenes. The
key here is the degree of difference of the individual described
properties.
[0006] The resulting curled fibres can then be laid to create a
batt that is subsequently bonded using various methods to create a
bulky nonwoven textile.
SUMMARY OF THE INVENTION
[0007] A batt according to the invention comprises crimped bi- or
multicomponent fibres consisting of at least two polymeric
components, which are mutually arranged across the cross section of
the fibers such that they promote crimping of the fibres during the
setting process and which differ in the crystallisation heat, where
the substance of the invention is that the difference in the
crystallisation heat (dHc) is in the range from 30 J/g to 5 J/g and
that the described polymeric components differ in at least one of
the other parameters selected from the group of melt flow index,
degree of polydispersion and the flexural modulus, while the
relative difference of the polymer components is:
[0008] for the flow index in the range from 100 g/10 min to 5 g/10
min and/or
[0009] for the degree of polydispersion in the range from 1 to 0.3,
and/or
[0010] for the flexural modulus in the in the range from 300 MPa to
50 MPa;
wherein the relative difference in the melt flow index is no
greater than 100 g/10 min, the relative difference in the degree of
polydispersity is no greater than 1, the relative difference in the
crystallisation heat is no greater than 300 MPa; and wherein said
fibres have the degree of crimping at least 5 crimps per 20 mm of
fibre. Preferred and/or specific embodiments of the invention are
defined in the dependent claims. In a further aspect, the invention
regards a method of production of such batts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A--examples of asymmetrical (crimping promoting)
arrangement of the component sections across the cross-section of a
multicomponent fibre
[0012] FIG. 1B--example of a symmetrical arrangement of the
component sections in the cross-section of a multicomponent
fibre
[0013] FIG. 2--example of spunmelt production line
DEFINITIONS
[0014] The term "batt" here refers to materials in the form of
fibres that are found in the state prior to bonding that is
performed during the calendering process described for example in
patent application WO2012130414. The "batt" consists of individual
fibres between which a fixed mutual bond is usually not yet formed
even though they may be pre-bonded in certain ways, where this
pre-bonding may occur during or shortly after the laying of fibres
in the spunlaying process. This pre-bonding, however, still permits
a substantial number of the fibres to be freely moveable such that
they can be repositioned. The here-mentioned "batt" may consist of
several strata created by the deposition of fibres from several
spinning beams in the spunlaying process.
[0015] The terms "fibre" and "filament" are in this case mutually
interchangeable.
[0016] The term "monocomponent fibre" refers to a fibre formed of a
single polymer or polymer blend, as distinguished from bicomponent
or multicomponent fibre.
[0017] "Bicomponent" refers to a fibre having a cross-section
comprising two discrete polymer sections, two discrete polymer
blend sections, or one discrete polymer section and one discrete
polymer blend section. The term "bicomponent fibre" is encompassed
within the term "multicomponent fibre". A bicomponent fibre may
have an overall cross-section divided into two or more sections
consisting of differing sections of any shape or arrangement,
including for example, a coaxial arrangement, core-and-sheath
arrangement, side-by-side arrangement, radial arrangement, etc.
[0018] The term "multicomponent" refers to a fibre having a
cross-section comprising more than one discrete polymer section, or
more than one polymer blend section, or at least one discrete
polymer component and at least one polymer blend section. The term
"multicomponent fibre" thus includes, but is not limited to,
"bicomponent fibre". A multicomponent fibre may have an overall
cross-section divided into parts consisting of differing sections
of any shape or arrangement, including, for example, a coaxial
arrangement, core-and-sheath arrangement, side-by-side arrangement,
radial arrangement, islands-in-the-sea arrangement, etc.
[0019] As used herein, the term "nonwoven textile" means a
structure in the form of a fleece or webbing formed from directed
or randomly oriented fibres, from which initially a batt is formed
and which is subsequently consolidated and fibres are mutually
bonded by friction, effects of cohesive forces, gluing or by
similar methods creating a single or multiple bonding patterns
consisting of bonding imprints formed by a bounded compression
and/or the effect of pressure, heat, ultrasound or heat energy, or
a combination of these effects if necessary. The term does not
refer to fabrics formed by weaving or knitting or fabrics using
yarn or fibres to form bonding stitches. The fibres may be of
natural or synthetic origin and may be staple fibres, continuous
fibres or fibres produced directly at the processing location.
Commonly available fibres have diameters in the range from
approximately 0.0001 mm to approximately 0.2 mm and are supplied in
several forms: short fibres (known also as staple or chopped
fibres), continuous individual fibres (filaments or monofilaments),
untwisted bundles of continuous fibres (known also as tow) and
twisted bundles of continuous fibres (yarn). A nonwoven textile can
be produced using many methods, including technologies such as
meltblown, spunbond, spunmelt, spinning from solvents,
electrostatic spinning (electrospinning), carding, film
fibrillation, melt-film fibrillation, airlaying, dry-laying,
wetlaying with staple fibres and various combinations of these
processes as known in the art. The basis weight of nonwoven
textiles is usually expressed in grams per square metre (gsm).
[0020] The term "asymmetry" when used with respect to the
perpendicular plane of the fibre cross-section means that the
arrangement of the fibre sections is not symmetrical, particularly
respective to the central symmetry, where the centre is considered
to be the centre of the fibre cross-section. The term may also
relate to axial symmetry, where it is necessary to assess at least
as many axes passing through the centre of the cross-section of the
fibre as there are polymer sections present.
[0021] The term "heat" is understood to mean "melting heat" or
"crystallisation heat" and is always understood to mean "latent
heat".
DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] According to this invention a batt may consist of continuous
multicomponent fibres produced for example from spunmelt process.
Fibres are extruded under a spinneret and subsequently attenuated,
cooled and laid down on a belt so as to form a batt of fibres.
During the course of the process these fibres will curl
automatically. The batt may be converted to the nonwoven
fabric.
[0023] The individual fibres consist of at least two polymer
components A and B, where the polymer components are delivered to
the spinneret separately and in the resulting fibre there is a
section with a predominance of the A polymer component and a
section with a predominance of the B polymer component and wherein
the sections in the cross-section of the fibre are arranged in a
manner that supports the crimping of the fibres already during the
course of the setting process of the fibre. These areas can, for
example, be found on the opposite sides of the fibre cross-section
and so form an arrangement known in bicomponent fibres under the
name side-by-side or, for example, one section may surround the
second section and so form an arrangement know as core-sheath,
where for the purpose of ensuring the crimping of the fibre, the
overall arrangement of both sections with predominant polymeric
components A,B is asymmetrical in cross-section. In another
arrangement, the fibre may contain three polymer sections with
predominant polymer components A, B, C arranged, for example in the
arrangement known as "segmented pie" or "islands-in-the-sea", where
for the purpose of ensuring the crimping of the fibre, the overall
arrangement of both sections with predominant material components
A,B is asymmetrical in the cross-section.
[0024] Without intent to be bound by theory, it is believed that
the mutual arrangement of the sections with predominant polymer
components in the cross-section of the fibre modified to support
crimping of fibres is already, during the course of the fibre
setting, expressed, for example by the degree of asymmetry of the
polymer components, which significantly affect the final crimping
result, while it is not possible to simply assume that a greater
asymmetry of fibre arrangement will result in more pronounced
crimping. On the contrary, it is necessary to also take into
consideration the properties of the individual components, where
arrangement synergies may arise and a fibre with a less pronounced
asymmetrical arrangement may foster greater crimping than a fibre
with a more pronounced degree of asymmetry. A person skilled in the
field will appreciate that the optimal arrangement of sections with
predominant polymer compoment in the fibre can be determined in a
laboratory test, for example, using a small laboratory spinneret.
Examples of the individual asymmetrical arrangements and examples
of arrangements supporting fibre crimping, not limited to those
presented here, are shown in FIG. 1A. The arrangements that--based
on the above provided definition--are not asymmetrical or generally
do not support fibre crimping are shown in FIG. 1B.
[0025] The formation of crimped fibres resulting from a significant
difference in the properties of the individual polymer components,
commonly expressed using the so-called contractibility of
individual components is well known in the industry. Fibres
produced in this way are known under the name of chemically formed
fibres. A person skilled in the art will appreciate that the term
component contractibility describes primarily the volume change
during the transition from the liquid to the solid state, which is
affected by the various properties of the polymers. For example,
for a bicomponent fibre it is possible to use the combination of
two polymers. For example one polymer together with another polymer
(polypropylene+polyethylene), copolymers
(polypropylene+polypropylene copolymer) or a blend
(polypropylene+polypropylene blend and a polypropylene copolymer).
When using two polymers it is always necessary to very carefully
consider the used materials and their mutual miscibility. The more
they differ from each another, the more probable is a lower level
of cohesion of both sections with predominant polymer component in
the fibre and splitting of the fibre may occur. Especially in
hygiene applications even a small degree of fibre splitting is very
undesirable as it may manifest itself as "fuzz balls" on the
surface of the textile and so appear on the surface of the product,
which the end customers see as a sign of an inferior quality
product. It is also known that the same polymer with differing
properties (for example a difference in the melt flow index,
polydispersion, degree of crystallinity of the material or its
elasticity) may be used, where for success it is essential to have
a significant difference in at least one of the parameters.
[0026] For example, based on the European patent EP0685579 from
Kimberly Clark, in the case of polydispersion a difference of at
least 0.5 is necessary in the precisely determined area--the
document indicates that predominant component of one has a
polydispersion of <2.5 and the second >3, for crystallinity
it is necessary that predominant component of one section is
amorphous and the other is crystalline, while the difference in the
melting heat must be at least 40 J/g; while the melt flow index
suitable for spunmelt applications is in the range from single
digits to thousands of g/10 min and for elasticity a combination of
elastic and non-elastic material is required.
[0027] The subject of this invention is crimped multicomponent
fibre where the used polymers predominant in sections are very
similar to each other. Preferably the polymers can be chemically
the same, just a bit differ in physical properties, e.g.
polypropylene-polypropylene combination. A person skilled in the
art will appreciate, that for example polypropylene (polymer made
from propylene monomer units) have basic characteristics, but for
example tacticity of single units, or length of polymer chains or
distribution of different polymer chains in polymer can bring
variability in physical properties, that is significant for fiber
and nonwoven production. A person skilled in the field will
appreciate the wide range of commercial types of polymers available
on the market and will also appreciate the various amounts and
availability of the individual types. Due to the distribution in
demand, the offer is also concentrated particularly at polymers in
a relatively narrow area of properties. A considerable advantage
arising from the use of significantly similar polymers is also that
they are relatively readily available on the market.
[0028] It is necessary to stress that the mentioned polymer
sections may be formed using one polymer or may be formed using a
blend of various compounds. It is known in the industry that there
also exist fibres consisting of multicomponent fibres based on the
same polymer, the components differing only in the addition of an
admixture. For example US file 6,203,905 from Kimberly Clark
describes the addition of a nucleation additive into one section of
the bicomponent fibre.
[0029] The principle of our invention may consists of predominant
polymeric components only or of predominant components and added
additives.
The principle of our invention may also contain the addition of
additives (for example dyes), but the addition of such an additive
does not affect the crimping of fibres to a significant degree. The
additive may, for example, be added to both sections symmetrically.
As is known in the industry, some functional additives may induce a
chemical reaction directly in the polymer melt immediately before
spinning and their effectiveness may be affected, for example by
the temperature of the melt (for example IRGATEC CR76 from BASF).
In this way, by effect of the various temperatures of the melt of
both polymer component for sections, a significant difference in
the resulting properties (for example melt flow index,
polydispersion, etc.) may arise even when identical mixtures of
polymers and additives are used in both sections. The principle of
the invention may contain the addition of functional additives, but
this addition does not affect the crimping of fibres to a
significant degree.
[0030] As is evident from the preceding text, it is known in the
industry that if the contractibility of the predominant components
of sections is sufficiently different then tension arises in the
fibre under the spinneret causing crimping. The crimping of fibres
based on the invention results from the combination of small
differences in at least two, preferably three parameters of the
polymer.
[0031] The key variable is the latent heat of crystallisation
(dHc), which is an indicator of the amount of energy that it is
necessary to take from the system in order for the crystallisation
of the polymer components to occur. A well-known theory states that
if the temperature difference is sufficient then predominant
component in one section will start setting first, and as such
created tension has no opposing force in the form of still liquid
predominant component in the second section, the fibre will curl.
It is always necessary to have a sufficient difference between both
polymer components otherwise the effect will not take place.
[0032] A known document Kimberly-Clark EP0685579 determines the
minimum difference in the melting heat, which equates approximately
to a crystallisation heat of 40 J/g. In contrast, according to the
invention, the crimping of the fibres occurs at smaller
differences, when a surprisingly significant synergistic effect of
other differences between the predominant component in sections is
taken advantage of. The curling or crimping of fibres based on the
invention results from the combination of small differences in the
crystallisation heat (dHc) and in at least one, preferably two more
parameters of the polymer.
[0033] The individual predominant components differ in the heat of
crystallisation (dHc), where the difference in the values is in the
range of 30 J/g to 5 J/g, better yet 30 J/g to 10 J/g, and
preferably 30 J/g to 20 J/g. For lower degree of crimping the heat
of crystallisation difference (dHc) can be in the range of 24 J/g
to 5 J/g, better yet 24 J/g to 10 J/g, and preferably 24 J/g to 20
J/g. Furthermore, the individual predominant components may differ
in the melt flow index (MFI) level, where the difference between
the values is in the range of approximately 100 g/10 min to 5 g/10
min, better yet 80 g/10 min; preferably 60 g/10 min to 10 g/10
min.
[0034] The individual predominant components may, furthermore,
differ in the degree of the material's polydispersion, where the
difference in the values is in the range 1 to 0.3, better yet 1 to
0.5 and preferably 1 to 0.75.
[0035] The individual predominant components may, furthermore,
differ in the flexural modulus of the material, where the
difference in the values is in the range 300 MPa to 50 MPa, better
yet 250 MPa to 80 MPa and preferably 200 MPa to 80 MPa.
[0036] Without need to be bound by theory we assume that the
curling of the fibre is caused by the tension in the fibre, when
one section is already crystalline, while the other remains in the
liquid state or that its degree of crystallisation is lower at that
given point in time. In general, during the course of
crystallisation the volume of the given section becomes smaller and
if at that given time the other section is still malleable, it does
not present a very large level of resistance and the fibre curls.
From the above mentioned it may appear that apart from the value of
the latent heat of crystallisation (dHc) itself, also the
temperature at which crystallisation commences and the speed of the
crystallisation may also have an effect on the degree of curling.
Respecting the fact that the subject of the invention is the
combination of two significantly similar polymers, they will
probably also have similar crystallisation temperatures. Examples
of various commercial types of homopolymers of polypropylene are
shown in the table.
TABLE-US-00001 Crystallisation of Latent heat Crystallisation
temperature crystallisation speed Polymer/manufacturer .degree. C.
(dHc) J/g (min) Mosten NB425 from 124 108 1.36 Unipetrol Tatren
HT2511 from 125 106 0.77 Slovnaft MR 2002 from Total 114 85 5.29
Petrochemicals Achieve 3854 from Exxon 113 91 8.19 Moplen HM562S
from 121 87 1.55 Basel
[0037] Without need to be bound by theory we assume that the
differences in the crystallisation time in the order of several
minutes do not have significant force in themselves to cause
curling in the fibres, but also contribute to the degree of curling
caused by the above mentioned differences, namely in the latent
heat of crystallisation (dHc).
[0038] The individual predominant components of sections may differ
in the crystallisation temperature, where the difference in the
values is in the range of approximately 5-30.degree. C., better yet
5-25.degree. C. and preferably 8-25.degree. C.
[0039] The individual predominant components of sections may differ
in crystallisation speed, where the difference in the values is at
least 20 seconds, better yet 50 seconds, better yet 120 seconds and
preferably 150 seconds.
[0040] The polymer components are dosed (1) into separate extrusion
systems (2), where they are melted, heated to a suitable operating
temperature and still separated brought to the spinnerets (4) where
the multicomponent fibre is formed. A person skilled in the art
will understand that the process for preparing polymers for
spinning in the form of a multicomponent fibre may, depending on
the type of technology encompass further specific steps, as well as
the fact that various additives designed for this purpose may be
added to the polymer components for the purpose of for example
changing the colour of the fibres (dyes) or to change the
properties of the fibres (for example hydrophilicity,
hydrophobicity, inflammability), where according to the invention
it is significant for the material that these additive do not
affect the crimping of fibres and/or they are dispersed
symmetrically in the resulting fibre. The fibre (5) formed under
the spinneret (8) is exposed to a stream of cooling and attenuating
air (6,7), so crimps form on the fibres before they fall (8) on to
the collecting mat (10). Both cooling and attenuating air (6,7) has
approximately the room temperature, preferably 10-30.degree. C.,
more preferably 15-25.degree. C. The collecting mat (10) may, for
example, be a moving belt that carries away the forming fibre batt
(11). During the way on collecting mat (10) there is no extra heat
or mechanical energy entrance to support the crimping.
[0041] In this way, several spinning beams can be arranged in
sequence, where they all may produce crimped fibres or may lay
different layers (e.g. simple spunmelt fibres--e.g. spunbond or
meltblown, nanofibres, a film, etc.). For the design according to
the invention, it is advantageous if the layer/layers of crimped
fibres are laid down on other layers so that undesirable
compression of the crimped fibres does not occur. For other
applications it might be advantageous to perform combinations where
crimped fibres are released from the first and last spinning beams
so that the resulting material has the outer surfaces consisting of
crimped fibres and the inner layer can have different properties
(for example mechanical strength of the resulting nonwoven
textile).
[0042] The layer or layers of fibres are subsequently strengthened
(12), where several known methods may be used (for example thermal
bonding, thermal calender bonding, needle punching,
hydroentanglement, etc.). The individual bonding methods have a
significant effect on the resulting properties of the materials and
a person skilled in the field will easily determine which method is
suitable for their material. Likewise, this skilled person will
also understand that the selection of a bonding method with a
higher intensity or bonding point density may result even in
negating the differences in the overall bulkiness of the resulting
nonwoven textile containing fibres based on the invention and
standard materials containing non-crimped fibres.
[0043] Final nonwoven web, can be used at various applications as
for non limited list of following examples: both dusting and
hygiene wipes including wet wipes; parts of furniture; parts of
household equipment including for example tablecloth, counterplead,
etc; covering material; parts of hygiene absorbent articles for all
babies, femcare and adult inco as for example it can create or be
part of nonwoven landing zone, ADL (Acquisition Distribution
Layer), backsheet, topsheet, side panels, core wrap, leg cuffs
etc.
EXAMPLES
Example 1
Design Based on the Invention
[0044] A batt consist of continuous bicomponent fibres, where one
component consists of polypropylene MR 2002 from Total
Petrochemicals and the second component consists of polypropylene
Mosten NB425 from Unipetrol. Both polypropylene homopolymer
materials are readily available on the market, both are inelastic
and crystalline.
TABLE-US-00002 MR 2002 from Mosten Total NB425 from Petrochemicals
difference Unipetrol Melt flow index (MFI) 15 10 25 (g/10 min)
Polydispersion (PDI) 2.6 0.8 3.4 Latent heat of crystallisation
85.00 J/g 23.1 J/g 108.1 J/g (dHc J/g) Flexural modulus of the 1300
MPa 100 MPa 1400 MPa material
[0045] The fibres were produced on a Reicofil 3 production line for
spunmelt nonwoven textiles and removed from the lied batt prior to
the bonding of the material.
Example 1A
[0046] Continuous bicomponent fibre was of the side-by-side type
and the individual sections were formed in the weight ratio 40:60.
First section consists of polypropylene MR 2002 and second section
consist of polypropylene Mosten NB425. [0047] The average degree of
crimping achieved was 13.4 crimps/20 mm.
Example 1B
[0048] Continuous bicomponent fibre was of the side-by-side type
and the individual sections were formed in the weight ratio 30:70.
First section consists of polypropylene MR 2002 and second section
consist of polypropylene Mosten NB425. [0049] The average degree of
crimping achieved was 15.8 crimps/20 mm.
Example 1C
[0050] Continuous bicomponent fibre was of the side-by-side type
and the individual sections were formed in the weight ratio 65:35.
First section consists of polypropylene MR 2002 and second section
consist of polypropylene Mosten NB425. [0051] The average degree of
crimping achieved was 8.2 crimps/20 mm.
Example 1D
[0052] Continuous bicomponent fibre was of the side-by-side type
and the individual sections were formed in the weight ratio 50:50.
First section consists of polypropylene MR 2002 and second section
consist of polypropylene Mosten NB425. [0053] The average degree of
crimping achieved was 11.7 crimps/20 mm.
Example 2
Design Based on the Invention
[0054] A batt consist of continuous bicomponent fibres, where one
component consists of polypropylene MR 2002 from Total
Petrochemicals and the second component consists of polypropylene
Tatren HT2511 from Slovnaft. Both polypropylene homopolymer
materials are readily available on the market, both are inelastic
and crystalline.
TABLE-US-00003 Tatren MR 2002 from HT2511 Total from Petrochemicals
difference Slovnaft Melt flow index (MFI) 15 10 25 (g/10 min)
Polydispersion (PDI) 2.6 0.1 2.7 Latent heat of crystallisation
85.00 J/g 21 J/g 106.0 J/g (dHc J/g) Flexural modulus of the 1300
MPa 100 MPa 1400 MPa material
[0055] The fibres were produced on a Reicofil 3 production line for
spunmelt nonwoven textiles and removed from the lied batt prior to
the bonding of the material.
Example 2A
[0056] Continuous bicomponent fibre was of the side-by-side type
and the individual sections were formed in the weight ratio 30:70.
First section consists of polypropylene MR 2002 and second section
consist of polypropylene Tatren HT2511. [0057] The average degree
of crimping achieved was 15.9 crimps/20 mm.
Example 2B
[0058] Continuous bicomponent fibre was of the side-by-side type
and the individual sections were formed in the weight ratio 40:60.
First section consists of polypropylene MR 2002 and second section
consist of polypropylene Tatren HT2511. [0059] The average degree
of crimping achieved was 12.8 crimps/20 mm.
Example 2C
[0060] Continuous bicomponent fibre was of the side-by-side type
and the individual sections were formed in the weight ratio 50:50.
First section consists of polypropylene MR 2002 and second section
consist of polypropylene Tatren HT2511. [0061] The average degree
of crimping achieved was 12.0 crimps/20 mm.
Example 2D
[0062] Continuous bicomponent fibre was of the side-by-side type
and the individual sections were formed in the weight ratio 70:30.
First section consists of polypropylene MR 2002 and second section
consist of polypropylene Tatren HT2511. [0063] The average degree
of crimping achieved was 7.3 crimps/20 mm.
Example 3
Design Based on the Invention--Lab Line
[0064] A batt consists of continuous bicomponent fibres, fibers
produced on a laboratory spinning line with compressed air filament
attenuating up to 0.9 MPa, spinning die with 12 holes, hole
diameter 0.5 mm, hole length 0.8 mm. Extrusion system with two
independent extruders (diameter 16 mm). Line throughput 0.5 gram
per minute per hole. Line is available for example at Research
Institute for Man-Made Fibres "VUCHV a.s. Svit", Slovak
Republik.
Example 3A
[0065] Continuous bicomponent fibre was of the side-by-side type
and the individual sections were formed in the weight ratio 40:60.
First section consists of polypropylene MR 2002 and second section
consist of polypropylene Tatren HT2511. Attenuating air pressure
was 0.85 MPa.
Example 3B
[0066] Continuous bicomponent fibre was of the side-by-side type
and the individual sections were formed in the weight ratio 40:60.
First section consists of polypropylene MR 2002 and second section
consist of polypropylene Mosten NB425. Attenuating air pressure was
0.85 MPa.
TABLE-US-00004 Predom. Predom. Predom. polymer polymer polymer in
second in second differ- differ- in first section section ence ence
section 3A 3B 3A 3B Material MR 2002 Tatren Mosten Tatren/ Mosten/
HT2511 NB425 MR 2002 MR 2002 Melt flow 15 25 25 10 10 index (MFI)
(g/10 min) Polydispersion 2.6 2.7 3.4 0.1 0.8 (PDI) Latent heat of
85 106 108.1 21 23.1 crystallisation (dHc J/g) Flexural 1300 1400
1400 100 100 modulus of the material Fiber properties 3A 3B fiber
thickness 2.2 2 (dtex) STN EN ISO 1973 Tensile 2.7 2.8 (cN/dtex)
STN EN ISO 5079 Elongation (%) 393.5 376.3 STN EN ISO 5079 Degree
of 14.5 14.5 crimping (crimps per 20 mm fiber)
Example 4
Design Based on the Invention--Including Calendering
[0067] Continuous bicomponent fibre was of the side-by-side type
and the individual sections were formed in the weight ratio 40:60.
First section consists of polypropylene MR 2002 and second section
consist of polypropylene Tatren HT2511. Both polypropylene
homopolymer materials are readily available on the market, both are
inelastic and crystalline.
TABLE-US-00005 Tatren MR 2002 from HT2511 Total from Petrochemicals
difference Slovnaft Melt flow index (MFI) 15 10 25 (g/10 min)
Polydispersion (PDI) 2.6 0.1 2.7 Latent heat of crystallisation
85.00 J/g 21 J/g 106.0 J/g (dHc J/g) Flexural modulus of the 1300
MPa 100 MPa 1400 MPa material
[0068] The fibres were produced on a Reicofil 4 SSS production line
for spunmelt nonwoven textiles.
[0069] Attenuating air temperature 15-25.degree. C. .degree. C.,
cabine pressure in the area 2800-3200 Pa. The batt was thermobonded
using pair of smooth-gravure rolls with Ungricht design U2888M
(standard oval). Smooth roll temperature 170-180.degree. C.,
gravure roll temperature 160-170.degree. C., nip 120-125
daN/cm.
[0070] The fibers removed from the lied batt prior to the bonding
of the material had the average degree of crimping 15.7 crimps/20
mm.
[0071] Final Material Properties:
TABLE-US-00006 measured samples averadge standard amount value
deviation Basis weight [gsm] 10 45.0 0.63 Tensile Strength, WSP
110.4 [N/50 10 67.5 20.73 MD (09) mm] Tensile Strength, WSP 110.4
[N/50 10 42.7 12.63 CD (09) mm] Elongation at Peak, WSP 110.4 [%]
10 43.5 11.18 MD (09) Elongation at Peak, WSP 110.4 [%] 10 43.1
8.59 CD (09)
Testing Methodology
[0072] "Degree of crimping" of the fibre is measured using the
method described in the norm {hacek over (C)}SN 80 0202 from 1969.
Measurement is performed on individual fibres under standard
conditions (an individual fibre is loosely placed on a mat for 24
hours at a temperature of 20.degree. C. and at a relative humidity
of 65%). The fibre is subsequently hung vertically and subject to a
strain of 0.0076 g (for a fibre with a fineness of 1-5 den). The
number of crimps is counted on a length of 20 mm.
[0073] "Polydispersion" of a polymer or also the "coefficient of
polydispersion (PDI)" expresses the heterogeneity of a material. It
is identified by a calculation of the numerical (Mn) and the weight
(Mw) average molar weight of the polymer, where PDI=Mw/Mn, as
described for example at Modern Physical Organic Chemistry from
Eric V. Anslyn and Dennis A. Dougherty.
[0074] "Melt flow index (MFI)" of a polymer is measured using a
testing methodology according to the German norm ASTM D1238-95; the
specific test conditions (e.g. temperature) vary for the individual
polymers--for example the test conditions for polypropylene are
230/2.16 and for polyethylene they are 190/2.16.
[0075] "Flexural modulus" of a polymer is measured using the
testing methodology described in ISO 178:2010.
[0076] "Crystallinity", "latent heat of crystallisation",
"temperature of crystallisation" and the "melting temperature" are
measured using the testing methodology describe in ASTM D3417 using
DSC, where the speed in the temperature is 2.degree. C./min in the
measured range of 200-80.degree. C. and the sample volume is 7-7.4
g.
[0077] "Speed of crystallisation" of a polymer is measured using
the ISO 11357-7--Determination of crystallization
kinetics--isothermal crystallisation method, where a sample is
first kept at the melt temperature of 210.degree. C. for 8 minutes
and subsequently cooled to 120.degree. C.
INDUSTRIAL APPLICABILITY OF THE INVENTION
[0078] The batt produced according to the invention are applicable
namely for the production of nonwoven textiles, where they can form
a production step on an online production line. The nonwoven
textile produced from the batt made according to the invention is
widely applicable in various fields, namely in hygiene products
such a baby diapers, feminine absorptive products or incontinence
products. Crimped fibres create a fluffiness in the textile meaning
that the material can be advantageously used both in applications
requiring softness and silkiness (for example parts of absorptive
products, which are in direct contact with the user's skin) and in
applications requiring bulkiness (wipes, loop side in the "hook and
loop" system, etc.).
* * * * *