U.S. patent application number 13/836357 was filed with the patent office on 2014-09-18 for monofilament yarn for a paper machine clothing fabric.
This patent application is currently assigned to VOITH PATENT GMBH. The applicant listed for this patent is VOTIH PATENT GMBH. Invention is credited to Vikram Dhende, Brian Good, Yidan Zhu.
Application Number | 20140272371 13/836357 |
Document ID | / |
Family ID | 50231169 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140272371 |
Kind Code |
A1 |
Good; Brian ; et
al. |
September 18, 2014 |
MONOFILAMENT YARN FOR A PAPER MACHINE CLOTHING FABRIC
Abstract
A paper machine clothing (PMC) fabric includes a plurality of
monofilament yarns, at least some of which have a composition which
is a thermoplastic resin. The thermoplastic resin yarns have
physical properties including a water absorption of less than
approximately 6% and a loop tenacity of greater than approximately
8.0 grams/denier.
Inventors: |
Good; Brian; (Summerville,
SC) ; Dhende; Vikram; (Summerville, SC) ; Zhu;
Yidan; (Goose Creek, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VOTIH PATENT GMBH |
Heidenheim |
|
DE |
|
|
Assignee: |
VOITH PATENT GMBH
Heidenheim
DE
|
Family ID: |
50231169 |
Appl. No.: |
13/836357 |
Filed: |
March 15, 2013 |
Current U.S.
Class: |
428/221 ; 264/6;
428/401; 528/324 |
Current CPC
Class: |
Y10T 428/298 20150115;
D21F 1/0027 20130101; D21F 7/08 20130101; Y10T 428/249921
20150401 |
Class at
Publication: |
428/221 ;
428/401; 528/324; 264/6 |
International
Class: |
D21F 1/00 20060101
D21F001/00 |
Claims
1. A paper machine clothing (PMC) fabric including a plurality of
monofilament yarns, at least some of said yarns having a
composition comprised of a thermoplastic resin, each of said yarns
having physical properties including a water absorption of less
than approximately 6% and a loop tenacity of greater than
approximately 8.0 grams/denier.
2. The PMC fabric according to claim 1, wherein said thermoplastic
resin is a polyamide resin.
3. The PMC fabric according to claim 2, wherein said polyamide is
polyamide 6/6T (PA6/6T) copolymer resin.
4. The PMC fabric according to claim 1, wherein said composition
has a knot tenacity which is greater than 3.0 grams per denier.
5. The PMC fabric according to claim 4, wherein said knot tenacity
is greater than 5.0 grams per denier.
6. The PMC fabric according to claim 1, wherein said composition
has a tenacity which is greater than 5.5 grams per denier.
7. The PMC fabric according to claim 6, wherein said composition
has a tenacity greater than 6 grams per denier.
8. The PMC fabric according to claim 1, further comprising at least
one stabilizer.
9. The PMC fabric according to claim 8, wherein said stabilizer is
selected to improve a plurality of antioxidant properties of said
monofilament.
10. The PMC fabric according to claim 1, wherein said yarns having
said thermoplastic resin composition have a diameter between
approximately 0.05 and 0.70 millimeters (mm).
11. The PMC fabric according to claim 1, wherein said loop tenacity
is greater than 10 grams per denier.
12. The PMC fabric according to claim 1, wherein said yarns having
said composition comprised of said thermoplastic resin have an
abrasion resistance which is greater than polyamide 6,12 (PA6,12)
alone.
13. The PMC fabric according to claim 12, wherein said yarns having
said composition comprised of said thermoplastic resin have an
abrasion resistance which is 50% greater than polyamide 6,12
(PA6,12) alone.
14. The PMC fabric according to claim 13, wherein said yarns having
said composition comprised of said thermoplastic resin have an
abrasion resistance which is 100% greater than polyamide 6,12
(PA6,12) alone.
15. A paper machine clothing (PMC) fabric yarn for use in a PMC
fabric, said PMC yarn having a composition comprised of a
thermoplastic resin, each of said yarns having physical properties
including a water absorption of less than approximately 6% and a
loop tenacity of greater than approximately 8.0 grams/denier.
16. The PMC fabric yarn according to claim 15, wherein said
thermoplastic resin is a polyamide resin.
17. The PMC fabric yarn according to claim 16, wherein said
polyamide resin is a polyamide 6/6T (PA6/6T) copolymer resin.
18. The PMC fabric yarn according to claim 15, wherein said
composition has a knot tenacity which is greater than 3.0 grams per
denier.
19. The PMC fabric yarn according to claim 15, wherein said
composition has a tenacity which is greater than 5.5 grams per
denier.
20. The PMC fabric yarn according to claim 15, said PMC fabric yarn
having a diameter between approximately 0.05 and 0.70 millimeters
(mm).
21. The PMC fabric yarn according to claim 15, wherein said
composition has a water absorption which is less than polyamide 6
(PA6) alone.
22. A method of manufacturing a paper machine clothing (PMC) fabric
yarn for use in a PMC fabric, said method comprising the steps of:
extruding a polyamide 6/6T (PA6/6T) copolymer resin; spinning said
PA6/6T copolymer resin into a filament; and drawing said filament
into a monofilament PMC fabric yarn having physical properties
including a water absorption of less than 6 percent (%) and a loop
tenacity of greater than 8.0 grams per denier.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a paper machine clothing,
and more particularly, to the composition of monofilaments used in
the paper machine clothing.
[0003] 2. Description of the Related Art
[0004] A paper machine clothing (PMC) fabric is typically carried
by a number of rolls in a paper machine, and travels at a high
speed. Vacuum boxes are used to pull moisture from the web through
the PMC. This creates multiple friction points within the paper
machine that wear down the PMC fabric and cause an increase in
power consumption. The individual yarns making up a PMC fabric
require several desirable physical properties, such as modulus of
elasticity, relative elongation, abrasion resistance, fibrillation
resistance, water absorbency, and a low coefficient of
friction.
[0005] PMC fabrics, particularly in the forming and press sections
of a papermaking machine, come into contact with large volumes of
water. In the forming section, water based pulp is deposited on a
porous forming fabric and water is extracted from the pulp by
gravity and suction through the forming fabric. In the next stage,
the wet fibrous web is transported on a felt and passes through nip
rollers to squeeze out additional water remaining in the web.
Finally, the web is completely dried by the application of heat on
a porous dryer fabric to generate a paper sheet.
[0006] Polyamides such as PA6 and PA6,6 have been utilized in the
paper machine clothing industry. However, a common problem
associated with each of these polyamides is that they absorb a
considerable amount of water in the papermaking process due to the
hydrogen bonding capacity of the amide linkages present in the
polymer structure. This results in a decrease in advantageous
monofilament properties and dimensional changes to the fabric,
which can lead to marking of the fibrous material web being
produced thereon.
[0007] Attempts have been made to improve the absorption of
polyamide fabrics by the use of additives. For example, one
approach to overcome the issue has been to incorporate carbon
nanotubes (CNT), molybdenum disulfide (MoS.sub.2), tungsten
disulphide (WS.sub.2) or glass fibers. However, these approaches
may result in adverse effects on the yarn tensile properties.
[0008] What is needed in the art is a PMC fabric yarn which has
lower water absorption than the state of the art and improved
tenacity, loop and knot strength. The PMC fabric yarn should
further be simple and cost effective to produce.
SUMMARY OF THE INVENTION
[0009] The present invention provides a paper machine clothing
(PMC) fabric with monofilaments having a composition which is a
thermoplastic resin, namely polyamide 6/6T (PA6/6T) copolymer
resin. The polyamide copolymer is formed from polyamide 6 and
polyamide 6T. The resulting monofilament has a decreased water
absorption over a monofilament formed of polyamide 6 (PA6) alone.
Polyamide 6T (PA6T) contains an aromatic component which helps in
reducing the moisture content or water uptake of the PA6/6T
copolymer resin. This structural component is also responsible for
improvement in the tensile properties such as tenacity, loop
strength and knot strength of the material. The PA6/6T copolymer
resin also has improved loop tenacity over PA6 alone.
[0010] The invention in one form is directed to a PMC fabric
including a plurality of monofilament yarns. At least some of the
yarns have a composition which is a PA6/6T copolymer resin. The
yarns formed of the PA6/6T copolymer resin have a water absorption
of less than approximately 6% and a loop tenacity of greater than
approximately 8.0 grams/denier.
[0011] The invention in another form is directed to a PMC fabric
yarn for use in a PMC fabric. The PMC yarn has a composition which
is a PA6/6T copolymer resin. The PMC fabric yarn has a water
absorption of less than approximately 6% and a loop tenacity of
greater than approximately 8.0 grams/denier.
[0012] The invention in yet another form is directed to a method of
manufacturing a PMC fabric yarn for use in a PMC fabric. The method
includes the steps of: providing a PA6/6T resin; forming the PA6/6T
copolymer resin into a filament; and drawing the filament into a
monofilament PMC fabric yarn having a water absorption of less than
6 percent (%) and a loop tenacity of greater than 8.0 grams per
denier.
[0013] Advantageously, the PA6/6T copolymer resin composition of
the PMC yarns according to the present invention provide for
reduced water uptake, improved tensile properties, simplicity in
processing and does not require the use of additives to effectively
stand the test of time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above-mentioned and other features and advantages of
this invention, and the manner of attaining them, will become more
apparent and the invention will be better understood by reference
to the following description of embodiments of the invention taken
in conjunction with the accompanying drawings, wherein:
[0015] FIG. 1 is a fragmentary, perspective view of a portion of a
fabric including an embodiment of a monofilament yarn of the
present invention;
[0016] FIG. 2 is a side view of a portion of a press felt including
monofilament yarns according to the present invention; and
[0017] FIG. 3 is a flowchart illustrating an embodiment of the
method of making monofilament yarns of the present invention.
[0018] The exemplifications set out herein illustrate embodiments
of the invention and such exemplifications are not to be construed
as limiting the scope of the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Referring now to the drawings, and more particularly to FIG.
1, there is shown a portion of an embodiment of a PMC fabric 10
including a plurality of woven monofilament yarns 12. Yarns 12 have
a diameter of between approximately 0.05 and 0.70 millimeters, but
this may vary between applications. The specific configuration of
fabric 10 may vary, depending upon the application. For example,
the specific weave pattern of fabric 10 may vary from one
application to another. Moreover, fabric 10 need not necessarily be
a woven fabric, but may include non-woven yarns, such as a press
felt 10 including yarns 12, an example of which is illustrated in
FIG. 2.
[0020] At least some of yarns 12 have a composition formed from a
thermoplastic resin, such as a polyamide resin, and more
particularly a polyamide 6/6T (PA6/6T) copolymer resin. The
thermoplastic resin yarns have a water absorption of less than
approximately 6%, for example approximately 5.5%. In any case, the
composition of the thermoplastic yarns, and thus the yarns, has a
water absorption which is less than polyamide 6 (PA6) alone.
Further, the thermoplastic resin has a loop tenacity value of
greater than 8.0 grams per denier, for example greater than 10
grams per denier or greater than 12 grams per denier.
[0021] The thermoplastic resin yarns 12 have a knot tenacity which
is greater than 3.0 grams per denier, for example greater than 5.0
grams per denier. The tenacity of the composition, or more
specifically of yarns formed of the same thermoplastic composition,
is greater than 5.5 grams per denier, for example greater than 6.0
grams per denier. The thermoplastic resin yarns 12, for example the
PA6,6T yarns according to the present invention, have an abrasion
resistance which is greater than polyamide 6,12 alone, for example
50% greater than polyamide 6,12 alone, or 100% greater than
polyamide 6,12 alone.
[0022] Optionally, the composition forming yarns 12 may further
include at least one stabilizer, particularly a stabilizer selected
to improve antioxidant properties of the monofilament yarn formed,
for example benzofuranones and hindered phenols.
Example
[0023] Table 1 below shows a comparison of the tensile properties
of monofilament yarns produced with standard polyamide resins and a
monofilament yarn produced with the PA6/6T copolymer resin
according to the present invention. ASTM D2256-97 method was used
to carry out the tensile testing of the yarns. The water absorption
of the yarns was measured according to ASTM D570. The yarns were
submerged in distilled water at approximately 23.degree. C. for 24
hours. The samples were then removed, pat dried using lint free
cloth and weighed. Further, the abrasion resistance of the yarns
was measured using the squirrel cage method, which consists of the
use of a rotating drum of metal wires which are aligned
perpendicular to the polymer strands. A pretension is used on each
polymer strand prior to starting the drum. During the test, the
strands are continually abraded by the rotation of the drum and the
strand's abrasion resistance is quantified by the number of cycles
it takes for the strand to fail.
TABLE-US-00001 TABLE 1 Comparison of yarn properties of standard
polyamide resin (PA6, PA66, and PA6,12) and PA 6/6T Reference
Reference Reference Yarn 1 Yarn 2 Yarn 3 Sample A Resin PA 6 PA
6,12 PA 6,6 PA 6/6T Tenacity (g/den) 6.0 5.4 6.0 6.8 Shrinkage
(176.degree. C./ 16 6 6.3 23 5 min) Elongation (%) 27 25 23 35 Loop
tenacity (g/d) 6.3 6.0 6.3 12.2 Knot tenacity (g/d) 3.4 2.5 3.7 5.7
Water absorption (%) 12.5 4.5 10 5.5 Abrasion Resistance - # 32,000
13,000 29,000 29,000 of cycle to break
[0024] Referring now to FIG. 3, there is shown a flowchart
illustrating an embodiment of a method of making the monofilament
yarns of the present invention. During the manufacture of PMC
fabric 10, PA6/6T is provided, for example in pellet form. A screw
extruder is used, for example to melt the pelletized PA6/6T. (FIG.
3, block 14). Optionally, a stabilizer may be added into the
pellets prior to the extrusion step (block 14) and the stabilizer
melt blended with the pelletized PA6/6T. The extruded PA6/6T (and
optionally the stabilizer mixture) is then spun into a filament.
(FIG. 3, block 16). The filament is subsequently drawn into a
monofilament PMC fabric yarn (FIG. 3, block 18) having a water
absorption of less than approximately 6 percent and a loop tenacity
of greater than 8.0 grams per denier.
[0025] While this invention has been described with respect to at
least one 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.
* * * * *