U.S. patent application number 14/792780 was filed with the patent office on 2017-01-12 for monofilament, fabric and production method.
The applicant listed for this patent is VOITH PATENT GMBH. Invention is credited to VIKRAM DHENDE, BRIAN GOOD, MATTHEW ORR.
Application Number | 20170009385 14/792780 |
Document ID | / |
Family ID | 57730970 |
Filed Date | 2017-01-12 |
United States Patent
Application |
20170009385 |
Kind Code |
A1 |
DHENDE; VIKRAM ; et
al. |
January 12, 2017 |
MONOFILAMENT, FABRIC AND PRODUCTION METHOD
Abstract
A monofilament is particularly suited for use as a component in
an industrial textile such as a papermachine clothing (PMC) fabric.
The monofilament is formed from a composition including more than
70 weight % to 99 weight % polyamide and from 1 weight % to less
than 30 weight % polyphenylene ether.
Inventors: |
DHENDE; VIKRAM;
(SUMMERVILLE, SC) ; GOOD; BRIAN; (SUMMERVILLE,
SC) ; ORR; MATTHEW; (MABLETON, GA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VOITH PATENT GMBH |
HEIDENHEIM |
|
DE |
|
|
Family ID: |
57730970 |
Appl. No.: |
14/792780 |
Filed: |
July 7, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D01F 8/12 20130101; D10B
2331/02 20130101; D01D 5/12 20130101; D01F 8/16 20130101; D03D
15/00 20130101; D10B 2331/06 20130101; D21F 1/0027 20130101; D01F
6/90 20130101; D21F 7/08 20130101 |
International
Class: |
D01F 8/12 20060101
D01F008/12; D01D 5/12 20060101 D01D005/12; D03D 15/00 20060101
D03D015/00; D21F 7/08 20060101 D21F007/08; D01F 8/16 20060101
D01F008/16 |
Claims
1. A monofilament, comprising: a monofilament body formed from a
composition including more than 70 weight % to 99 weight %
polyamide, and from 1 weight % to less than 30 weight %
polyphenylene ether.
2. The monofilament according to claim 1, configured for use as a
component in an industrial textile such as a papermachine clothing
fabric.
3. The monofilament according to claim 1, wherein said composition
does not include any compatibilizer.
4. The monofilament according to claim 1, wherein said composition
does not include any compound belonging to the group consisting of
fumaric acid, maleic acid, itaconic acid, dimethylmaleate,
maleimide, tetrahydrophthalimide, maleic anhydride, itaconic
anhydride, glutaconic anhydride, citraconic anhydride and
tetrahydrophthalic anhydride.
5. The monofilament according to claim 1, wherein the composition
does not include any functionalized olefinic elastomer.
6. The monofilament according to claim 1, wherein a polymer part of
said composition is a binary mixture of polyamide and polyphenylene
ether.
7. The monofilament according to claim 1, wherein said polyamide is
selected from the group consisting of PA6, PA6.6, PA6.T, PA6.10,
PA6.12, PA6,6.6, PA4.10, PA5.6, PA5.10, PA5.12 and mixtures
thereof.
8. The monofilament according to claim 1, wherein said monofilament
body has a loop tenacity which is at least 20% greater than the
loop tenacity of a comparative monofilament, wherein the
comparative monofilament is formed in an identical manner as the
monofilament except that the polyphenylene ether is replaced by
polyamide.
9. The monofilament according to claim 1, wherein the monofilament
has a water absorption which is at least 15% less than a water
absorption of a comparative monofilament, wherein the comparative
monofilament is formed in an identical manner as the monofilament
except that the polyphenylene ether is replaced by polyamide, and
wherein the water absorption is determined by immersing the
respective monofilament in distilled water at 23.degree. C. for 24
h and weighing the respective monofilament before and after the
immersion process.
10. The monofilament according to claim 9, which comprises weighing
the respective monofilament before and after the immersion process
according to ASTM D570.
11. The monofilament according to claim 1, wherein the monofilament
has an abrasion resistance which is at least 50% greater than an
abrasion resistance of a comparative monofilament, wherein the
comparative monofilament is formed in an identical manner as the
monofilament except that the polyphenylene ether is replaced by
polyamide.
12. The monofilament according to claim 11, wherein the abrasion
resistance of the monofilament is at least 70% greater than the
abrasion resistance of the comparative monofilament.
13. The monofilament according to claim 1, wherein the monofilament
has a tenacity which is greater than 5.0 gf/den.
14. The monofilament according to claim 1, wherein the monofilament
has a thermal stability which is at least 10% greater than a
thermal stability of a comparative monofilament, wherein the
comparative monofilament is formed in an identical manner as the
monofilament except that the polyphenylene ether is replaced by
polyamide, and wherein the thermal stability is determined as a
percentage of a tenacity retention after exposing the respective
monofilament in an oven at 170.degree. C. for 24 h.
15. A fabric, comprising a plurality of woven or non-woven
monofilaments, wherein at least some of said monofilaments are
formed from a composition including more than 70 weight % to 99
weight % polyamide and 1 weight % to less than 30 weight %
polyphenylene ether.
16. The fabric according to claim 15 configured as a papermachine
clothing fabric.
17. The fabric according to claim 15, wherein the fabric is
completely made up from monofilaments which are formed from a
composition including more than 70 weight % to 99 weight %
polyamide and 1 weight % to less than 30 weight % polyphenylene
ether.
18. A method for forming a monofilament comprising the steps of:
preparing a resin composition including more than 70 weight % to 99
weight % polyamide and 1 weight % to less than 30 weight %
polyphenylene ether; extruding the resin composition through a
spinneret to form a monofilament; and drawing the monofilament for
one or more times.
19. A method of forming a papermachine clothing fabric, the method
comprising providing monofilaments according to claim 1 and forming
the monofilaments into the a papermachine clothing fabric.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to a monofilament, in
particular for use as a component in an industrial textile, such as
a papermachine clothing (PMC) fabric.
[0002] Monofilaments formed from polymeric resins are used as yarns
in a variety of industrial applications. For example, woven or
non-woven fabrics manufactured from polymeric monofilaments are
widely used in dryers, conveyors and the like. In particular,
endless fabric belts are important constituents of the dryer
sections, forming sections and press sections of paper machines.
Such fabrics, which are also called paper machine clothings (PMC),
are disclosed, for example, in commonly assigned patent application
publication US 2012/0214374 A1 and in its counterpart European
published patent application EP 2 489 781 A1.
[0003] Monofilaments which are to be used as yarns in an industrial
textile are often formed from polyamide (PA). Thermoplastic
polyamides generally have a high resiliency, a high abrasion
resistance as well as a high toughness. The mechanical properties
of monofilaments formed from polyamides are generally sufficient
for the above mentioned applications and in particular for the use
in the forming sections and press sections of paper machines. In
these sections, water based pulp is deposited on a porous forming
fabric manufactured from monofilaments. After the deposition of the
pulp, water is extracted from the pulp by gravity and suction.
During this extraction process, water passes through the pores of
the forming fabric. In a further stage of the paper production
process, the wet web prepared from the pulp is transported on a
press felt. Nip rollers or the like are used to squeeze out water
from the web. Finally, the web is dried on a porous dryer fabric by
supplying thermal energy.
[0004] The contact between the polyamide yarns and water during a
paper production process is problematic, because polyamides tend to
absorb a considerable amount of water. This effect is due to the
hydrogen bonding capacity of the amide linkages present in the
polymer structure. Water absorption affects the mechanical
properties of the monofilaments, resulting in dimensional changes
of the respective fabric. Therefore, the stability and durability
of PMC fabrics made from polyamide yarns is rather poor.
[0005] In order to reduce the water absorption capacity of
monofilaments formed from polyamide, chemically modified polyamides
and/or additives could be in principle used. However, such
approaches are disadvantageous because the tensile and abrasion
resistance properties of the monofilaments are reduced and the
material costs are increased. On account of these reasons there is
a need to enhance the stability of monofilaments for industrial
textiles while maintaining the tensile properties.
SUMMARY OF THE INVENTION
[0006] It is accordingly an object of the invention to provide a
monofilament, a production method and a fabric which overcome the
above-mentioned and other disadvantages of the heretofore-known
devices and methods of this general type and which provides a
monofilament which is easy to produce and which has a high
mechanical stability even when intensely exposed to moisture.
[0007] With the foregoing and other objects in view there is
provided, in accordance with the invention, a monofilament formed
from a composition including more than 70 weight % to 99 weight %
polyamide and from 1 weight % to less than 30 weight %
polyphenylene ether.
[0008] Polyphenylene ether (PPE) polymers are amorphous and
non-polar. Moreover, they have excellent mechanical and thermal
properties as well as being dimensional stable. The inventors have
surprisingly recognized that it is advantageous to combine the high
resiliency and abrasion resistance of polyamide with the high
stability and the low water absorption capacity of polyphenylene
ether. The aromatic component of the polyphenylene ether lowers the
overall polarity of the composition and thus reduces the water
uptake of the formed monofilament.
[0009] In principle, polyamide is poorly mixable with polyphenylene
ether. Surprisingly, however, it has been found that the
compatibility of polyamide and polyphenylene ether at comparatively
low loadings of polyphenylene ether is sufficient to produce stable
monofilaments. These monofilaments are easy to produce and have
excellent tensile and loop properties as well as high abrasion
resistance. Simultaneously reduced water absorption capacity should
lead to improved dimensional stability. Therefore, the invention
enables longer overall fabric life on a paper machine.
[0010] According to a particularly preferred embodiment of the
invention, the polymer part of the monofilament completely consists
of or at least essentially consists of the polyamide and the
polyphenylene ether as polymer ingredients. Specifically, the sum
of weights of the polyamide and the polyphenylene ether based on
the total weight of the polymer part of the monofilament may be at
least 80 weight %, preferably at least 90 weight %, more preferably
at least 95 weight %, even more preferably at least 99 weight % and
most preferably 100 weight %. Although it is preferred to use only
polyamide and polyphenylene ether as polymeric ingredients, the
composition may further comprise non-polymeric additives. For
certain applications, it may be advantageous to add further
polymers to the mixture of polyamide and polyphenylene ether.
However, maximizing of the amount of polymer in the composition
increases yarn tenacity.
[0011] Preferably, the composition does not include any
compatibilizer.
[0012] According to a preferred embodiment of the invention, the
composition does not include any compound belonging to the group
consisting of fumaric acid, maleic acid, itaconic acid,
dimethylmaleate, maleimide, tetrahydrophthalimide, maleic
anhydride, itaconic anhydride, glutaconic anhydride, citraconic
anhydride and tetrahydrophthalic anhydride. This maximizes ease of
processing and reduces the production costs.
[0013] In accordance with another preferred embodiment of the
invention, the composition does not include any functionalized
olefinic elastomer.
[0014] Notably good results are achieved when the polymer part of
the composition is a binary mixture of polyamide and polyphenylene
ether. I. e. it is preferred that the composition doesn't contain
any further polymers apart from polyamide and polyphenylene ether.
However, as stated above, such a preferred composition may contain
additional non-polymeric ingredients.
[0015] In a further development of the present invention, it is
proposed that the composition includes a stabilizer, in particular
an antioxidant.
[0016] Particularly good results are achieved when the
polyphenylene ether has a number average molecular weight of less
than 10000 g/mol. In accordance with the present invention, the
number average molecular weight is measured by gel permeation
chromatography making use of polystyrene standards.
[0017] In accordance with a still further embodiment of the
invention, the polyamide is selected from the group consisting of
PA6, PA6.6, PA6.T, PA6.10, PA6.12, PA6,6.6, PA4.10, PA5.6, PA5.10,
PA5.12 and mixtures thereof. These polyamides have turned out to
provide especially good results.
[0018] Notably good results are achieved when the polyamide is PA6
(polycaprolactam) or PA6.6 (nylon).
[0019] According to a further embodiment of the invention, the
monofilament has a loop tenacity which is at least 20% greater than
the loop tenacity of a comparative monofilament, wherein the
comparative monofilament is formed in an identical manner as the
monofilament except that the polyphenylene ether is replaced by
polyamide.
[0020] In accordance with the present invention, the loop tenacity
is determined by linking two loops of the monofilament or of two
respective monofilaments and pulling the loops against each
other.
[0021] In accordance with a still further embodiment of the
invention, the monofilament has a loop tenacity which is at least
approximately 40% greater than the loop tenacity of a comparative
monofilament, wherein the comparative monofilament is formed in an
identical manner as the monofilament except that the polyphenylene
ether is replaced by polyamide.
[0022] According to yet another embodiment of the present
invention, the monofilament has a loop tenacity ranging from 4
gf/den to 10 gf/den, preferably from 5.5 gf/den to 8.5 gf/den,
wherein "gf/den" means "grams force per denier" and wherein 1
gf/den.times.8.83 equals 1 cN/tex.
[0023] In accordance with still another embodiment of the present
invention, the monofilament has a water absorption which is at
least 15% less than the water absorption of a comparative
monofilament, wherein the comparative monofilament is formed in an
identical manner as the monofilament except that the polyphenylene
ether is replaced by polyamide, and wherein the water absorption is
determined by immersing the respective monofilament in distilled
water at 23.degree. C. for 24 h and weighing the respective
monofilament before and after the immersion process. Specifically,
the water absorption may be determined according to ASTM D570.
[0024] Preferably, the monofilament has a water absorption which is
at least approximately 30% less than the water absorption of a
comparative monofilament, wherein the comparative monofilament is
formed in an identical manner as the monofilament except that the
polyphenylene ether is replaced by polyamide, and wherein the water
absorption is determined by immersing the respective monofilament
in distilled water at 23.degree. C. for 24 h and weighing the
respective monofilament before and after the immersion process.
[0025] According to a further preferred embodiment of the present
invention, the monofilament has an abrasion resistance which is at
least 50% greater, preferably at least 70% greater, than the
abrasion resistance of a comparative monofilament, wherein the
comparative monofilament is formed in an identical manner as the
monofilament except that the polyphenylene ether is replaced by
polyamide. In accordance with the present invention, the abrasion
resistance is measured by the squirrel cage method as disclosed in
the above-mentioned US 2012/0214374 A1 and EP 2 489 781 A1.
[0026] Particularly good results are achieved when the monofilament
has a tenacity which is greater than 5.0 gf/den. In accordance with
the present invention, the tenacity is determined according to ASTM
D2256-97.
[0027] According to a further preferred embodiment of the present
invention, the monofilament has a thermal stability which is at
least 10% greater than the thermal stability of a comparative
monofilament, wherein the comparative monofilament is formed in an
identical manner as the monofilament except that the polyphenylene
ether is replaced by polyamide, and wherein the thermal stability
is determined as percentage of the tenacity retention after
exposing the respective monofilament in an oven at 170.degree. C.
for 24 h.
[0028] Moreover, it is preferred that the monofilament has an
elongation at break ranging from 10% to 50%, preferably from 20% to
35%. In accordance with the present invention, the elongation at
break is measured according to ASTM D2256-97.
[0029] In accordance with still another preferred embodiment of the
present invention, the monofilament has a maximum diameter ranging
from 0.005 mm to 5 mm, preferably from 0.05 mm to 2 mm. According
to the present invention, the term "maximum diameter" means the
maximum dimension in the cross-section of the monofilament.
Monofilaments having a dimension falling in this numeric value
range have been found to be specifically suited for PMC
applications. Generally, the monofilament according to the
invention may have a circular, oval or rectangular cross section.
Specifically, the cross-sectional shape of the monofilament may be
selected depending on the type of fabric or felt which is to be
produced and depending on the application field of the fabric or
felt.
[0030] Moreover, the present invention is directed to a fabric, in
particular a papermachine clothing (PMC) fabric, comprising a
plurality of woven or non-woven monofilaments, wherein at least
some of the monofilaments are formed from a composition including
more than 70 weight % to 99 weight % polyamide and 1 weight % to
less than 30 weight % polyphenylene ether.
[0031] Such a fabric is easy to produce, cost-effective and
sufficiently stable to be used in a high moisture environment, such
as the forming and press section of a paper machine.
[0032] Notably good results are achieved when the fabric is
completely made up from monofilaments which are formed from a
composition including more than 70 weight % to 99 weight %
polyamide and 1 weight % to less than 30 weight % polyphenylene
ether.
[0033] According to a further preferred embodiment of the present
invention, the fabric forms an endless belt. Such an endless belt
can be used as a conveyor belt or, preferably, as a dryer belt,
forming belt or press belt in a paper machine.
[0034] Therefore, according to still another embodiment of the
invention, the fabric has a sufficient mechanical and thermal
stability to be used as a dryer belt, forming belt or press belt in
a paper machine.
[0035] In addition, the present invention relates to a method for
forming a monofilament comprising the steps of preparing a resin
composition including more than 70 weight % to 99 weight %
polyamide and 1 weight % to less than 30 weight % polyphenylene
ether, extruding the resin composition through a spinneret to form
a monofilament and drawing the monofilament for one or more
times.
[0036] Apart from using a mixture of polyamide and polyphenylene
ether having a low loading of polyphenylene ether, the drawing of
the monofilament may be performed according to the principles that
are generally known in the field of monofilament production.
[0037] In accordance with still another preferred embodiment of the
present invention, the resin composition is extruded by means of a
standard extruder, such as a single screw extruder or a twin screw
extruder.
[0038] Particularly good results are achieved when the step of
preparing the resin composition includes the step of melt blending
a mixture of polyamide and polyphenylene ether.
[0039] Preferably, the melt blending is carried out without adding
any compatibilizer. This maximizes ease of processing and keeps the
production costs low.
[0040] Moreover, it is preferred that the step of preparing the
resin composition does not involve any chemical modification of the
polyamide.
[0041] in accordance with a concomitant feature, the invention is
also directed to the use of a monofilament as described above for
forming a papermachine clothing (PMC) fabric.
[0042] Other features which are considered as characteristic for
the invention are set forth in the appended claims.
[0043] Although the invention is illustrated and described herein
as embodied in a monofilament, a fabric, and a method of producing
the same, it is nevertheless not intended to be limited to the
details shown, since various modifications and structural changes
may be made therein without departing from the spirit of the
invention and within the scope and range of equivalents of the
claims.
[0044] The construction and method of operation of the invention,
however, together with additional objects and advantages thereof
will be best understood from the following description of specific
embodiments when read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0045] FIG. 1 is a fragmentary perspective view of a portion of a
fabric made up from monofilaments; and
[0046] FIG. 2 is a flowchart illustrating an embodiment of the
method of making monofilaments of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0047] Referring now to the figures of the drawing in detail and
first, particularly, to FIG. 1 thereof, there is shown a portion of
a fabric 10 formed from a plurality of woven monofilaments 12, or
monofilament bodies. The fabric 10 may be formed to provide an
endless belt. The monofilament bodies 12 have a diameter ranging
from 0.005 mm and 5 mm, depending on the application. The specific
weave pattern of the fabric 10 may vary from one application to
another. Moreover, fabric 10 need not necessarily be a woven
fabric, but may include non-woven monofilaments 12. The
monofilaments 12 shown in FIG. 1 have a circular cross section, but
this may vary depending on the application. In particular, the
monofilaments 12 may have an elliptical cross section or a
rectangular cross section with slightly rounded corners.
[0048] At least some of the monofilaments 12 and preferably all
monofilaments 12 making up the fabric 10 are formed from a resin
composition including more than 70 weight % to 99 weight %
polyamide and 1 weight % to less than 30 weight % polyphenylene
ether, as it is described above and for an exemplary embodiment
below.
Examples
[0049] Different samples of monofilaments were produced on the
basis of a polyamide (PA) resin and a polyphenylene ether (PPE)
resin. The polyamide resin was PA6 supplied by BASF. The
polyphenylene ether was Noryl SA120-100 supplied by SABIC. Of these
two polymers, binary mixtures having different PPE loadings were
prepared by melt blending as shown at 14 in FIG. 2. No
compatibilitizers were added to the mixtures. Monofilaments 12 or
yarns were produced by extruding the mixture through a spinneret in
a single screw extruder as shown at 16 in FIG. 2. The loading of
the PPE ranged from 5 weight % to 30 weight % as shown in Table 1
below. A comparative monofilament having a PPE loading of 0 weight
% was also prepared. Preblending into pellets was not necessary.
The monofilaments 12 were drawn so as to have a diameter of 0.40
mm, as is shown at 18 in FIG. 2.
[0050] Tensile properties of the monofilaments 12 thus produced
were evaluated according to ASTM D2256-97. The results are
indicated in Table 1.
[0051] The abrasion resistance of the monofilaments 12 was measured
using the squirrel cage method. This method is described in US
2012/0214374 A1 and EP 2 489 781 A1 and involves the use of a
rotating drum of metal wires which are aligned perpendicular to the
polymer strands. At the beginning of the test, a load is applied to
each strand. During the test the strands are continually abraded by
the rotation of the drum and the abrasion resistance is quantified
by the number of cycles it takes for the strand to fail. The
average number of cycles to break for the monofilaments 12 formed
from the PA-PPE-mixture was found to range between 16900 and 22700
(Table 1). In contrast, the comparative monofilament having a PPE
loading of 0% processed under similar conditions had an average
number of cycles to break of 10000. Hence, the abrasion resistance
is increased by more than 1.65 times with the addition of PPE.
Increasing the PPE loading above 30% resulted in a phase separation
of the components and in unacceptable monofilaments.
[0052] To determine the free shrinkage, the samples were kept in an
enclosed hot air oven at 177.degree. C. for 3 minutes in an
unrestrained condition. After this hot air treatment, the change in
the length of each sample was measured and the free shrinkage
percentage was calculated therefrom.
[0053] Apart from the abrasion resistance and the free shrinkage,
Table 1 shows further tensile properties of the monofilament
samples according to the present invention as well as of the
comparative monofilament. Thermal stability of the monofilaments
was evaluated by exposing the monofilaments to high temperatures
and measuring the tensile properties before and after the heat
treatment. Specifically, the samples were exposed to 170.degree. C.
for 24 hours in an enclosed hot air oven and retained tensile
strength of the monofilaments was expressed in percentage after the
heat treatment.
[0054] The water absorption of the monofilament samples was
measured according to ASTM D570. Specifically, the samples were
emerged in distilled water at 23.degree. C. for 24 hours. The
samples were then removed, dried using a lint free cloth and
weighed.
[0055] It can be deduced from Table 1 that the use of a
PA-PPE-composition having a comparatively low PPE loading enables
the production of monofilaments having a high stability, excellent
tensile and loop properties and a reduced water absorption at the
same time.
TABLE-US-00001 TABLE 1 Monofilament properties Abrasion Tenacity
Free Resistance Retention PPE Elongation Loop Shrinkage (number of
(Thermal Water Loading Tenacity at Break Tenacity (177.degree. C.;
cycles to Stability Absorption (%) (gf/den) (%) (gf/den) 3 min)
break) Test) (%) (%) 0 6.42 24.08 5.89 12.9 10000 14.64 6.29 5 6.47
26.12 7.52 13.5 16900 24.57 6.00 10 6.23 25.23 6.86 13.7 19400
35.63 4.55 15 5.79 25.17 7.97 13.7 22700 49.05 5.31 20 5.81 25.59
8.03 13.5 17800 42.51 5.32 30 5.81 31.85 6.56 13.4 20500 55.77
5.00
[0056] While this invention has been described with respect to a
preferred embodiment, the present invention can be further modified
within the spirit and scope of this disclosure. This application is
therefore intended to cover any variations, uses, or adaptations of
the invention using its general principles. Further, this
application is intended to cover such departures from the present
disclosure as come within known or customary practice in the art to
which this invention pertains and which fall within the limits of
the appended claims.
* * * * *