U.S. patent application number 12/578252 was filed with the patent office on 2011-04-14 for sheet and method of making sheet for support structures and tires.
This patent application is currently assigned to E.I. DU PONT DE NEMOURS AND COMPANY. Invention is credited to Alessandro Volpi.
Application Number | 20110086224 12/578252 |
Document ID | / |
Family ID | 43304853 |
Filed Date | 2011-04-14 |
United States Patent
Application |
20110086224 |
Kind Code |
A1 |
Volpi; Alessandro |
April 14, 2011 |
Sheet and Method of Making Sheet for Support Structures and
Tires
Abstract
A planar sheet comprises a plurality of polyamide yarns having a
yarn modulus of from 3.7 to 6.8 N/dtex, an elongation to break of
from 2.9 to 4.7% and a denier of from 130 to 15,000 and a plurality
of steel wires wherein the steel wire is provided with a first
crimp and a second crimp, the first crimp lying in a plane that is
substantially different from the plane of the second crimp. The
first and second crimp pitches and amplitudes of the steel wire are
such that, when the steel wire and polyamide yarns are combined,
the elongation to break of the wire is similar to that of the
polyamide yarn. The wires and yarns are arranged such that they are
oriented parallel to each other within the planar sheet. The sheet
has utility in the construction of elastomeric components for tires
and belts.
Inventors: |
Volpi; Alessandro; (Milan,
IT) |
Assignee: |
E.I. DU PONT DE NEMOURS AND
COMPANY
Wilmington
DE
|
Family ID: |
43304853 |
Appl. No.: |
12/578252 |
Filed: |
October 13, 2009 |
Current U.S.
Class: |
428/369 ; 28/143;
57/362; 72/371 |
Current CPC
Class: |
B29L 2030/003 20130101;
B60C 9/04 20130101; B60C 2009/2029 20130101; B29C 70/20 20130101;
B60C 9/0057 20130101; Y10T 428/2922 20150115; B60C 9/20
20130101 |
Class at
Publication: |
428/369 ; 57/362;
72/371; 28/143 |
International
Class: |
D02G 3/02 20060101
D02G003/02; D02G 3/22 20060101 D02G003/22; B21D 11/14 20060101
B21D011/14; D06C 29/00 20060101 D06C029/00 |
Claims
1. A planar sheet, comprising: (a) a plurality of polyamide yarns
having a yarn modulus of from 3.7 to 6.8 N/dtex, an elongation to
break of from 2.9 to 4.7% and a denier of from 130 to 15,000, (b) a
plurality of steel wires having a major cross sectional dimension
of from 0.04 to 1.10 mm, wherein (1) the steel wire is provided
with a first crimp and a second crimp, the first crimp lying in a
plane that is at least 20.degree. different from the plane of the
second crimp, (2) the first and second crimp pitches and amplitudes
of the steel wire are such that the elongation to break of the wire
is no greater than 20% different from that of the polyamide yarn,
(3) the steel wire has a composition comprising a minimum carbon
content of 0.60 to 1.10%, a manganese content ranging from 0.20% to
0.90% and a silicon content ranging from 0.10% to 0.90%, and (4)
the steel wires and polyamide yarns are oriented parallel to each
other within the planar sheet.
2. The planar sheet of claim 1, wherein the polyamide yarn
comprises poly (paraphenylene terephthalamide) filaments.
3. The planar sheet of claim 1, wherein the polyamide yarn has a
modulus of from 3.7 to 6.0 N/dtex.
4. The planar sheet of claim 1, wherein the polyamide yarn has a
modulus of from 4.4 to 5.4 N/dtex.
5. The planar sheet of claim 1, wherein the polyamide yarn has an
elongation to break of from 3.0 to 4.0%.
6. The planar sheet of claim 1, wherein the cross section of the
steel wire round or essentially round.
7. A support structure for a tire, comprising the planar sheet of
claim 1 in the form of a belt, a carcass, or a bead.
8. A tire comprising the planar sheet of claim 1.
9. A method of forming a planar sheet, comprising the steps of: (a)
providing a plurality of polyamide yarns having a yarn modulus of
from 3.7 to 6.8 N/dtex, an elongation to break of from 2.9 to 4.7%
and a denier of from 130 to 15,000, (b) optionally twisting a
plurality of polyamide yarns into a cabled yarn, (c) providing a
plurality of steel wires having a major cross sectional dimension
of from 0.04 to 1.10 mm and a composition comprising a minimum
carbon content of from 0.60 to 1.10%, a manganese content ranging
from 0.20% to 0.90%, and a silicon content ranging from 0.10% to
0.90%, (d) determining the desired pitch, amplitude and planar
arrangement of crimps to be applied to the steel wire such that the
crimps lie in two planes that are at least 20.degree. different
from each other and the steel wire has an elongation to break no
greater than 20% different from that of the polyamide yarn, (e)
crimping the steel wire in accordance with the crimp parameters
determined in step (d), (f) optionally twisting a plurality of
steels wires into a cabled wire, and (g) combining the desired
number of steel wires and/or steel cords, and the desired number of
polyamide yarns and/or polyamide cords in a planar arrangement such
that all the yarns, wires and cords are oriented parallel to each
other.
10. A method of forming a planar sheet, comprising the steps of:
(a) providing a plurality of polyamide yarns having a yarn modulus
of from 3.7 to 6.8 N/dtex, an elongation to break of from 2.9 to
4.7% and a denier of from 130 to 15,000, (b) providing a plurality
of steel wires having a major cross sectional dimension of from
0.04 to 1.10 mm and a composition comprising a minimum carbon
content of from 0.60 to 1.10%, a manganese content ranging from
0.20% to 0.90%, and a silicon content ranging from 0.10% to 0.90%,
(c) determining the desired pitch, amplitude and planar arrangement
of crimps to be applied to the steel wire such that the crimps lie
in two planes that are at least 20.degree. different from each
other and the steel wire has an elongation to break no greater than
20% different from that of the polyamide yarn, (d) crimping the
steel wire in accordance with the crimp parameters determined in
step (c), (e) twisting at least one crimped steel wire with at
least one polyamide yarn to form a composite hybrid steel-polyamide
cord into a steel cord, and (g) combining the desired number of
steel wires or cords, polyamide yarns or cords and composite hybrid
steel-polyamide cords in a planar arrangement such that all the
yarns, wires and cords are oriented parallel to each other.
11. The method of claim 9 or 10, wherein the polyamide yarn
comprises poly (paraphenylene terephthalamide) filaments.
12. The method of claim 9 or 10, wherein the polyamide yarn has a
modulus of from 3.7 to 6.0 N/dtex.
13. The method of claim 9 or 10, wherein the polyamide yarn has a
modulus of from 4.4 to 5.4 N/dtex.
14. The method of claim 9 or 10, wherein the polyamide yarn has an
elongation to break of from 3.0 to 4.0%.
15. The method of claim 9 or 10, wherein the cross section of the
steel wire is round or essentially round.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a planar sheet useful for
the reinforcement of tires and support structures.
[0003] 2. Description of the Related Art
[0004] Combinations of aramid fibers and metal strands have been
disclosed in United States Patent Application Publication
2004/0123930.
BRIEF SUMMARY OF THE INVENTION
[0005] This invention relates to a planar sheet that comprises
[0006] (a) a plurality of polyamide yarns having a yarn modulus of
from 3.7 to 6.8 N/dtex, an elongation to break of from 2.9 to 4.7%
and a denier of from 130 to 15,000,
[0007] (b) a plurality of steel wires having a major cross
sectional dimension of from 0.04 to 1.10 mm, wherein [0008] (1) the
steel wire is provided with a first crimp and a second crimp, the
first crimp lying in a plane that is at least 20.degree. different
from the plane of the second crimp, [0009] (2) the first and second
crimp pitches and amplitudes of the steel wire are such that the
elongation to break of the wire is no greater than 20% different
from that of the polyamide yarn, [0010] (3) the steel wire has a
composition comprising a minimum carbon content of 0.60 to 1.10%, a
manganese content ranging from 0.20% to 0.90% and a silicon content
ranging from 0.10% to 0.90%, and [0011] (4) the steel wires and
polyamide
[0012] This invention also relates to a method of forming a planar
sheet, comprising the steps of:
[0013] (a) providing a plurality of polyamide yarns having a yarn
modulus of from 3.7 to 6.8 N/dtex, an elongation to break of from
2.9 to 4.7 and a denier of from 130 to 15,000,
[0014] (b) optionally twisting a plurality of polyamide yarns into
a cabled yarn,
[0015] (c) providing a plurality of steel wires having a major
cross sectional dimension of from 0.04 to 1.10 mm and a composition
comprising a minimum carbon content of from 0.60 to 1.10%, a
manganese content ranging from 0.20% to 0.90%, and a silicon
content ranging from 0.10% to 0.90%,
[0016] (d) determining the desired pitch, amplitude and planar
arrangement of crimps to be applied to the steel wire such that the
crimps lie in two planes that are at least 20.degree. different
from each other and the steel wire has an elongation to break no
greater than 20% different from that of the polyamide yarn,
[0017] (e) crimping the steel wire in accordance with the crimp
parameters determined in step (d),
[0018] (f) optionally twisting a plurality of steels wires into a
cabled wire, and
[0019] (g) combining the desired number of steel wires and/or steel
cords, and the desired number of polyamide yarns and/or polyamide
cords in a planar arrangement such that all the yarns, wires and
cords are oriented parallel to each other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 shows a general view of a planar sheet of the
invention.
[0021] FIG. 2 shows in cross section one combination of yarns and
wires arranged in a sheet structure.
[0022] FIG. 3 shows in cross section another combination of yarns
and wires arranged in a sheet structure.
[0023] FIG. 4 shows in cross section a further combination of yarns
and wires arranged in a sheet structure.
DETAILED DESCRIPTION OF THE INVENTION
[0024] This invention relates to a planar sheet and by "planar" it
is meant a structure having length and width dimensions that are
considerably greater than the thickness dimension. In the context
of this invention, the surfaces of the planar sheets may not be
perfectly flat but may be of a ribbed nature. By "cord" it is meant
a strand comprising at least one polyamide yarn and at least one
steel wire that have been twisted together to form a hybrid cord.
By "hybrid" it is meant the cord contains at least two different
materials A cord can also mean a plurality of polyamide yarns that
have been twisted together to form a polyamide cord or a plurality
of steel wires that have been twisted together to form a steel
cord.
[0025] One feature of this invention is that, when combined, the
elongation at break of both the polyamide yarn and steel wire is
similar. The elongation at break of the steel wire should be no
more than +/- 20% different to that of the polyamide yarn. More
preferably the elongation difference should be no more than +/- 10%
and most preferably no more than +/- 5%. By virtue of having
matching or near matching elongations at break when combined, the
polyamide yarn and steel wire in the cord will break at essentially
the same time when the cord is subjected to a tensile load. The
steel wire is tailored to match the elongation at break of the
polyamide yarn by a double crimping process described below.
Crimped wire provides a wire having a higher elongation at break
when compared to a similar non-crimped wire.
[0026] A further aspect of this invention is that polyamide yarn
may be used that has a modulus much lower than the 6.5 N/dtex
specified in United States Patent Application Publication
2009/015917.
[0027] "Filament" as used herein means a relatively flexible,
macroscopically homogeneous body having a high ratio of length to
width across its cross-sectional area perpendicular to its length.
Herein, the term "fiber" is used interchangeably with the term
"filament".
[0028] A "yarn" is an assemblage of fibres or filaments to form a
continuous strand. In the context of this invention, the term
"yarn" also encompasses a "cabled yarn". A cabled yarn is a yarn
formed by twisting together two or more yarns. In this invention
the polyamide yarn is formed as part of the filament spinning
process.
Polyamide Fiber and Yarn
[0029] Aramid is the preferred polyamide polymer. The term "aramid"
means a polyamide wherein at least 85% of the amide (--CONH--)
linkages are attached directly to two aromatic rings. Suitable
aramid fibers are described in Man-Made Fibres--Science and
Technology, Volume 2, Section titled Fibre-Forming Aromatic
Polyamides, page 297, W. Black et al., Interscience Publishers,
1968. Aramid fibers and their production are, also, disclosed in
U.S. Pat. Nos. 3,767,756; 4,172,938; 3,869,429; 3,869,430;
3,819,587; 3,673,143; 3,354,127; and 3,094,511.
[0030] The preferred aramid is a para-aramid. The preferred
para-aramid is poly (p-phenylene terephthalamide) which is called
PPD-T. By PPD-T is meant the homopolymer resulting from
mole-for-mole polymerization of p-phenylene diamine and
terephthaloyl chloride and, also, copolymers resulting from
incorporation of small amounts of other diamines with the
p-phenylene diamine and of small amounts of other diacid chlorides
with the terephthaloyl chloride. As a general rule, other diamines
and other diacid chlorides can be used in amounts up to as much as
about 10 mole percent of the p-phenylene diamine or the
terephthaloyl chloride, or perhaps slightly higher, provided only
that the other diamines and diacid chlorides have no reactive
groups which interfere with the polymerization reaction. PPD-T,
also, means copolymers resulting from incorporation of other
aromatic diamines and other aromatic diacid chlorides such as, for
example, 2,6-naphthaloyl chloride or chloro- or
dichloroterephthaloyl chloride or 3,4'-diaminodiphenylether.
[0031] Additives can be used with the aramid and it has been found
that up to as much as 10 percent or more, by weight, of other
polymeric material can be blended with the aramid. Copolymers can
be used having as much as 10 percent or more of other diamine
substituted for the diamine of the aramid or as much as 10 percent
or more of other diacid chloride substituted for the diacid
chloride or the aramid.
[0032] Continuous para-aramid fibers are generally spun by
extrusion of a solution of the p-aramid through a capillary into a
coagulating bath. In the case of poly(p-phenylene terephthalamide),
the solvent for the solution is generally concentrated sulfuric
acid, the extrusion is generally through an air gap into a cold,
aqueous, coagulating bath. Such processes are generally disclosed
in U.S. Pat. Nos. 3,063,966; 3,767,756; 3,869,429, & 3,869,430.
The filament cross section is circular or essentially circular.
Para-aramid filament yarns are available commercially as
Kevlar.RTM. fibers, which are available from E. I. du Pont de
Nemours & Co., Wilmington, Del. (DuPont) and Twaron.RTM.
fibers, which are available from Teijin, Ltd.
[0033] The polyamide yarn of this invention has a yarn modulus in
the range of from 3.7 to 6.8 N/dtex, more preferably in the range
of from 3.7 to 6.0 N/dtex and most preferably in the range from 4.4
to 5.4 N/dtex. The yarn also has an elongation to break of from 2.9
to 4.7%, more preferably from 3.0 to 4.0% and a denier of from 130
to 15000. Examples of yarns having these properties is Kevlar.RTM.
29, Kevlar.RTM. 119 and Kevlar.RTM. 129 from DuPont.
Steel Wire
[0034] The steel composition comprises a carbon content of from
0.60% to 1.1%, a manganese content ranging from 0.20 to 0.90% and a
silicon content ranging from 0.10 to 0.90%. Other elements such as
sulphur, phosphorous, chromium boron, cobalt, nickel and vanadium
may each be present at a level below 0.5%.
[0035] The steel wire may have cross sections comprising one or
more axes of symmetry. For example, an oval or rectangular cross
section has two axes of symmetry and a triangular cross section has
three axes of symmetry. In preferred embodiments, the steel wire
cross section is round, or is essentially round.
[0036] The major cross sectional dimension of the wire is in the
range of from 0.04 mm to 1.1 mm and more preferably from 0.07 mm to
0.60 mm. In the case of a round cross section, this dimension is
the diameter. The wire is typically provided with a coating
conferring affinity for rubber. Such coatings include those that
can react with sulphur atoms in the rubber, such as copper, zinc
and alloys of such metals, for example brass. In a preferred
embodiment, zinc is used as the coating substrate when polyamide
yarns form the outer surface of the hybrid cord, otherwise brass is
the preferred coating material.
Crimping
[0037] The steel wire is crimped to produce a wire having a wave
form.
[0038] Preferably the wire has a first and second crimp where the
first crimp lies in a plane that is substantially different from
the plane of the second crimp. By substantially different we mean
that the crimp planes differ by an angle of at least 20.degree.,
more preferably by an angle of at least 60.degree. and most
preferably by an angle of at least 80.degree.. The first and second
crimps have a crimp pitch and crimp amplitude. Typical values for
amplitude are from 0.5 to 1.0 mm and values for pitch from 2.0 to
16.0 mm. However other crimp and pitch values may also be utilized
with this invention.
[0039] Depending on the elongation at break of the polyamide yarn
being used, the angle of the crimp planes and the first and second
crimp pitches and amplitudes are calculated to give a steel wire
having an elongation at break close to that of the polyamide yarn.
Preferably the elongation at break of the steel wire is no greater
than 20% different from that of the polyamide yarn, more preferably
the difference is no greater than 10% and most preferably the
difference is no greater than 5%. Ideally the elongations at break
of the polyamide yarn and steel wire are the same. Typical values
for elongation at break of the steel wire are in the range of from
2.3 to 5.7% and more preferably from 2.4 to 4.8%.
[0040] The steel wire may be crimped by passing them through
toothed wheels. Such a process is described in European Patent (EP)
1036235 B1. Crimped wires of this type are available from N. V.
Bekaert S. A., Zwevegem, Belgium under the tradename High Impact
Steel.
Forming the Planar Sheet
[0041] In one embodiment, this invention relates to a method of
forming a planar sheet, comprising the steps of:
[0042] (a) providing a plurality of polyamide yarns having a yarn
modulus of from 3.7 to 6.8 N/dtex, an elongation to break of from
2.9 to 4.7% and a denier of from 130 to 15,000,
[0043] (b) optionally twisting a plurality of polyamide yarns into
a polyamide cord.
[0044] (c) providing a plurality of steel wires having a major
cross sectional dimension of from 0.04 to 1.10 mm and a composition
comprising a minimum carbon content of from 0.60 to 1.10%, a
manganese content ranging from 0.20% to 0.90%, and a silicon
content ranging from 0.10% to 0.90%,
[0045] (d) determining the desired pitch, amplitude and planar
arrangement of crimps to be applied to the steel wire such that the
crimps lie in two planes that are at least 20.degree. different
from each other and the steel wire has an elongation to break no
greater than 20% different from that of the polyamide yarn,
[0046] (e) crimping the steel wire in accordance with the crimp
parameters determined in step (d),
[0047] (f) optionally twisting a plurality of steels wires into a
steel cord, and
[0048] (g) combining the desired number of steel wires and/or steel
cords and the desired number of polyamide yarns and/or polyamide
cords in a planar arrangement such that all the yarns, wires and
cords are oriented in a direction parallel to each other.
[0049] In another embodiment, this invention also relates to a
method of forming a planar sheet, comprising the steps of:
[0050] (a) providing a plurality of polyamide yarns having a yarn
modulus of from 3.7 to 6.8 N/dtex, an elongation to break of from
2.9 to 4.7% and a denier of from 130 to 15,000,
[0051] (b) providing a plurality of steel wires having a major
cross sectional dimension of from 0.04 to 1.10 mm and a composition
comprising a minimum carbon content of from 0.60 to 1.10%, a
manganese content ranging from 0.20% to 0.90%, and a silicon
content ranging from 0.10% to 0.90%,
[0052] (c) determining the desired pitch, amplitude and planar
arrangement of crimps to be applied to the steel wire such that the
crimps lie in two planes that are at least 20.degree. different
from each other and the steel wire has an elongation to break no
greater than 20% different from that of the polyamide yarn,
[0053] (d) crimping the steel wire in accordance with the crimp
parameters determined in step (c),
[0054] (e) twisting at least one crimped steel wire with at least
one polyamide yarn to form a composite hybrid steel-polyamide cord,
and
[0055] (g) combining the desired number of steel wires, polyamide
yarns and composite hybrid steel-polyamide cords in a planar
arrangement such that all the yarns, wires and cords are oriented
parallel to each other.
[0056] Wire cords are produced by twisting a plurality of the steel
wires together to form a unitary multi-wire cabled wire structure.
Preferably, the number of steel wires cabled together is either two
or three. Similarly a plurality of polyamide yarns may also be
cabled together to form a multi-yarn cabled cord structure.
Preferably, the number of aramid yarns cabled together is either
two or three. Individual yarns of polyamide may, of course, also be
twisted with steel wire to produce a composite polyamide-steel
cord. In preferred embodiments the total number of polyamide yarns
in the composite cord is from one to ten and the total number of
steel wires in the composite cord is from one to eight. In
preferred embodiments, the twist multiplier of the yarn and wire
forming the cord is at least 0.8. Twist multiplier is a term well
understood in the textile arts. Methods such as twisting, plying or
cabling to combine the polyamide yarn and steel wire into a cord
are well known in the art and are further detailed in chapter 3.2
of Wellington Sears Handbook of Industrial Textiles.
[0057] The planar sheet comprises yarns, wires or cords all
oriented in the same direction. This is normally referred to as the
X or machine direction. The plane of the sheet is referred to as
the XY plane. The Y direction is orthogonal to the X direction.
Such an arrangement is shown generally in FIG. 1 where the X
direction is shown by 10 and the Y direction by 11. There are a
variety of ways in which polyamide yarns or cords and crimped steel
wires or cords may be combined to form a planar sheet suitable for
use with rubbers and elastomers. One such embodiment is shown in
cross section in FIG. 2 where polyamide yarns, 20, alternate with
steel wires, 21. In another embodiment as in FIG. 3, a plurality of
polyamide yarns are arranged to form a first sub-section, 30 and a
plurality of wires arranged to form a second subsection, 31. These
subsections are then arranged adjacent to each other. FIG. 4 shows
a further extension on this concept where two arrays of polyamide
yarns 40 comprising a different number of yarns in each array are
combined with two arrays of wires, 41 with these wire arrays also
having a different number of wires in each array. As can be seen,
the potential combinations of polyamide and steel both in terms of
number of yarns or crimped wires and their positioning in the sheet
relative to each other is quite extensive. The above description is
not limited to polyamide yarn or steel wire. Polyamide cord, steel
cord or composite steel-polyamide cord may also be included in the
above structures. Thus a planar sheet could comprise polyamide
yarns, polyamide cords, steel wire, steel cords and composite
steel-polyamide cords. The length and width of the planar sheet is
only limited by manufacturing constraints.
[0058] Methods of aligning yarns, wires and cords are well known in
the textile, rope and wire forming industries. Such methods include
the use of creels and beams to assemble the materials prior to
feeding the individual strands through a collimating station and
winding up the final assembly on a spool. Alternatively, sheets may
be cut to length after collimation. Binders, films and adhesives
may optionally be used to assist in maintaining the cohesiveness of
the planar sheet. Another means of achieving this is to incorporate
some light binder yarns in the Y direction either on the surface of
or woven into the sheet.
[0059] In preferred embodiments, the weight percentage of polyamide
in the sheet is from 10 to 50 weight percent based on the total
weight of polyamide and steel.
Support Structures and Tires
[0060] The planar sheet is useful for example in passenger car
tires, truck and bus tires as well as motorcycle tires. In
comparison to pure steel reinforcement cord, the composite hybrid
cord reduces weight in the tire and improves rolling
resistance.
[0061] To incorporate the planar sheet into a tire, one or more
sheets is incorporated into a matrix to form a support structure,
in the form of a carcass, a bead reinforcement chaffer (a composite
strip for low sidewall reinforcement), or of a belt strip. The
matrix can be any polymeric material that can keep multiple cords
in a fixed orientation and placement with respect to each other.
Typical materials are thermoset materials such as rubbers; however
it is also possible to use thermoplastic materials such as
thermoplastic vulcanisates and copolyetheresters. The support
structure is then fitted into the structure of the tire, typically
under the tread. If desired, the composite hybrid cord can be used
in other support structures for use in applications that need
elastomeric reinforcement.
* * * * *