Note: Descriptions are shown in the official language in which they were submitted.
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TIRE CORD FABRIC WITH GREATER
TWIST CORDS IN THE SELVEDGE AREA
The presen-t invention relates to tire cord
fabrics suitable for reinforcement of radial tires and more
particularly to such tire cord fabrics in which the degree
of twist in the warp cords in the selvedge areas is at least
three times greater than the degree of twist in the warp
cords in the body of the tire cord fabric.
Tire cord fabrics are widely used as reinforcing
mem~ers for rubber tires. In the reinforcement of radial
tires, the tire cord fabric is often composed of thick
cords, for example 1880 to 4200 dtex, as warp cords and
common spun yarns as weft yarns. The warp density is
usually in the range of from about 5 to 14 cords/cm over a
width of about 1.5 m and the weft density i3 usually in the
range of from about 2 to 100 yarns/m. The overall length of
this tire cord fabric, referred to sometimes hereinafter as
a roll of intermediate material, is usually about 1000 to
3000 m.
In preparing tire cord fabric for use in
constructing tire carcasses Eor radial tires, pieces of the
fabric of a length sufficient to run Erom bead to bead of
the tire and to provide for the required "turn-ups" are cut
off the roll of intermediate material at an angle of 90 to
the direct.ion of the warp cords. These pieces,
subsequently, may be spliced together, the selvedge portion
of one piece overlapping the selvedge portion of the next
piece, to produce a new roll of tire cord fabric with the
warp cords running transverse to the length of the roll.
In recent years the number of plies used in tire
construction has been greatly reduced, for example, monoply
tires are now being produced, in order to achieve better
performance, especially to provide a softer ride and lower
heat build up.
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If identical warp cords and the same number of
warp cords/cm are used in the selvedge portions as in the
remainder of the fabric, the resistance to stress in the
area of the selvedge to selvedge overlap splice is much
greater than the resistance to stres.s in -the remainder of
the tire cord fabric. When tire cord fabric containing such
a splice is used as a carcass ply in a two ply or especially
a monoply radial tire, the splice area affects tire
uniformity (i.e. tire run out or force variation) and also
manifests itself as an unsightly indentation in the sidewall
of the tire when the tire is in1ated. The indentation
appears because the higher resistance to stress in the
splice area does not allow the tlre to expand as much in
that area.
Canadian Patent 1 096 273 of Saito et al., issued
1981 February 24 and a division thereof, Canadian Patent
1 105 808, issued 1981 July 26, disclose two techniques for
improving tire uniformity by reducing the thickness of the
spl:ice areas. One technique is to make tire cord fabrics
with selvedge portions having warp cords each with a
diameter ~0% to 80% of the diameter of the warp cords in the
remainder of the tire fabric and the other technique is to
make tire cord fabric having a substantially lower number of
warp cords in the selvedge portions than in the remainder of
the fabric.
It is often inconvenient and/or expensive to
produce tire cord fabrics having selvedge portions with
lower diameter warp cords or with a lower number of warp
cords/cm than the remainder of the tire cord fabric.
Surprisingly, it has now been found that tire
uniformity may be greatly improved and the indentation in
the tire sidewall greatly reduced, if the selvedge portions
of the tire cord fabric in the splice area are formed by
warp cords each having a degree of twist at least three
times as high as the degree of twist of the warp cords in
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the remainder of the tire cord fabric.
Accorclingly, the present invention provides in a
tire cord fabrlc suitable for reinforcement of rubber tires,
the fabric comprising a plurality oE bodies and at least one
splice, each body being composed of two selvedge portions
and a rernaining central portion and containing therein a
large number oE warp cords arranged side by side and
parallel to the selvedge portions, the warp cords being
relatively coarsely interlaced with weft yarns, said splice
being formed by overlapping the selvedge portion of one body
with the selvedge portion of an adjoining body, the
improvement comprising each of the selvedge portions having
warp cords with a degree oE twist at least three times as
high as the degree of twist of the warp cords in the central
portions.
In an embodiment of the tire cord fabric of the
present invention, the degree of twist in the warp cords in
each selvedge portion is in the range of from three to six
times the degree of twist in the warp cords in the central
portion.
In other embodiments oE the tire cord fabric of
the present invention, the splice has a width in the range
of ~Erom 'i mm to 15 mm and especially a width of about
lO rnm.
In further embodlments of the tire cord fabric of
the present invention, the bodies are rubberized bodies.
The present invention also provides a tire cord
fabric suitable for reinforcement of rubber tires, the
fabric comprising: a first body, a second body and a splice
joining the two bodies, the first body being composed of two
selvedge portions and a remaining central portion and the
second body being composed of one selvedge portion and a
remaining portion having an edge opposite the selvedge
portion, the ~two bodies containing a large number of warp
cords arranged side by side and parallel to the selvedge
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portions, -the warp cords being relatively coarsely
interlaced with wet yarns, the splice being formed by
overlapping one selvedge portion of the first body with the
edge opposite the selvedge portion of the second body, each
of the selvedge portions having warp cords with a degree of
twist at least three times as high as the degree of twist of
the warp cords in the remaining portions of the two bodies,
the splice having a width in the range of from 5 mm to
15 mm.
In an embodiment of the tire cord fabric of the
present invention, the degree of twist in the warp cords in
each selvedge portion is in the range of rom three to six
times the dlegree oE twist in the warp cords in the remaining
portions of the two bodies.
In another embodiment of the tire cord fabric of
the present invention, the warp cords in each selvedge
portion have a diameter in the range of from 82% -to 99% of
the diameter of the warp cords in the remaining portions of
the two bodies.
In yet another embodiment oE the tire cord fabric
of the present invention, the splice has a width of about
10 mm.
In further embodiments of the tire cord fabric oE
the present invention, the two bodies are rubberized
bodies.
Tire cord fabrics of the present invention may be
manuEactured from continuous filament yarns of, for example,
nylon, polyester, rayon and mixtures thereof. Particularly
suitable nylon yarns are nylon 6 yarns and nylon 66 yarns.
The tire cords are usually made up by combining and twisting
together at least two yarns. The yarns may contain twist or
may contain no twist. If the yarns contain twist they are
usually twiste!d together in the opposite twist direction to
form the tire cords. The "degree of twist" of a tire cord
as used herein means the number of turns/cm which are
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applied in twisting -the yarns together to form the cord.
In making the tire cord fabric, it is preferable
that fabric first be made up as a roll oE in-termediate
~ material having, for example, a width of about 1.5 m and a
ri 5 length of about 1000 to 3000 m. In making a roll of
intermediate material, the tire cords, which are thick
cords, for example 1880 to 4200 dtex, are used as warp cords
and common spun yarns are used as weft yarns.
The warp density is preferably in the range of
from 5 to 14 cords/cm, especially 11 cords/cm and the weft
~, density is preferably in the range of from 20 to 100
i yarns/m. Selvedge portions, preferably having a width offrom 5 mm to 15 mm, more preferably a width of from 8 mm to
12 mm and especially a width of about 10 mm, are provided at
each edge of the roll of intermediate material. In the
selvedge portions of the roll of intermediate material, the
warp cords, which run parallel to the selvedge portions,
have a degree of twist at least three times as high, and
pre!ferably from three to six times as high, as the degree of
twist in the warp cords in the remaining portion.
Before the roll of intermediate material is used
to make t:ire cord fabric of the present invention, it is
pre!ferrecl that the intermediate material be rubberized. The
rubberizing of the intermediate material may be carried out
as 011O~8: (1) an adhesive is applied to the material and
the material is then heat treated under conditions as
required to stabilize its properties; and (2) the material
is then coated with an unvulcanized coating rubber.
Pieces of fabric of a length sufficient to run
from bead to bead of a tire and to provide for the required
"turn-ups" are cut off the roll of intermediate material at
an angle of 90 to the direction of the warp cords.
In an embodiment of the tire cord fabric of the
present invention, the pieces of fabric, subsequently, are
spliced toget:her, the selvedge portion of one piece
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overlapping -the selvedge portion of the next piece, to
produce a new roll of tire corcl fabrlc with the warp cords
runnin~ transverse to the length of the roll. The width of
each splice is preferably the same as the width of each
selvedge portion i.e. preferably from 5 mm to 15 mm, more
preferab]y from 8 mm to 12 mm and especially about 10 mm.
This tire cord fabric is useful in the construction of tire
carcasses for radial tires.
In another embodiment of the tire cord fabric of
the present invention, the pieces of fabric cut off the roll
of intermedia-te material are not spliced together selvedge
portion to selveclge portion to form a new roll of fabric.
Instead these pieces (pieces A i.e. Al, A2, etc.) are used
to make new pieces (pieces B i.e. Bl, B2, etc.). The new
pieces B may be prepared as follows: (1) a first new piece,
Bl, is cut off from piece Al to the required length; (2) the
remaining portion of piece Al is spliced to piece A2, the
cut off edge overlapping a selvedge portion of piece A2; (3)
a second new piece, B2 is cut off from the joined material
such that piece B2 contains the splice; (4) the remaining
portion of piece A2 is then spliced to piece A3 and the
procedure is repeated to produce a number of piece~ B most
of which contain a selvedge portion to body material splice.
The width of each splice is preferably the same as khe width
o each selvedge portion, i.e. preferably from 5 mm to lS
mm, more preferably from 8 mm to 12 mm and especially about
10 mm. In making such pieces B, it may be advantageous for
the warp cords in the selvedge portions of the roll of
intermediate material from which pieces A are cut ~o also
have a diameter in the range of from 82% to 99% of the
diameter of the warp cords in the remaining portion of the
intermediate material. These pieces B of tire cord fabric
are also useful in the construction of tire carcasses for
radial tires.
The present invention is il:Lustrated by the
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following examples:
EXAMPLE I
An intermediate material having two selvedge
portions and a body portion was made up and ruhberized, as
discussed hereinbefore. Some characteristics of the
intermedi.ate material were as follows:
Selvedge Portions
warp cord: nylon 66 cord of 2800 dtex formed from two
1~00 dtex nylon 66 yarns, each having a
twist of four turns/cm in the same twist
direction, by combining and twisting the
two yarns together at our turns/cm in the
opposite twist direction to produce cord
with a degree of twist of four turns/cm.
15 warp density: 11 cords/cm
width of each
selvedge portion: 10 mm
Body Portion
warp cord: nylon 66 cord of 2800 dtex formed from two
1~00 dtex nylon 66 yarns, each having no
twist, by combining and twis-ting the two
yarns together at one turn/cm to produce a
cord with a degree of twist of one
turn/cm.
warp density: 11 cords/cm
From the above it is apparent that the warp cords
in the selvedge portions have a degree of twist equal to
four times the degree of twist of the warp cords in the body
portion.
Pieces of fabric of a length sufficient to run
from bead to bead of a particular size of radial tire and to
provide for the required "turn-ups" were cut from the
intermediate material at an angle of 90 to the direction of
the warp cords. These pieces of fabric were then spliced
together, the selvedge portion of one piece overlapping the
selvedge portion of the next piece, to produce a new fabric
with the warp cords running transverse to the length of the
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fabric. The width of each splice in -the cord fabric was
10 mm.
A number o lengths of new fabric were used for
the carcasses of radial tires as follows:
Tir,e size: FR 78-14 (radial construction)
Carcass Ply: monoply
Tests on two o the above tires each containing
tire cord fabric according to the present invention with a
selvedge portion to selvedge portion splice revealed that:
(1) the uniformity of the tires was acceptable
as indicated by radial load variation measurements.
(2) the splice indentations in the sidewalls of
the tires were also acceptable ranging from 0 mm to 0.14 mm
in depth when the tires were inElated to 275 kPa.
EXAMPLE II
An intermediate material having two selvedge
portions and a body portion was made, rubberized and wound
up as a roll. Some characteristics o the roll of
intermediate material were as ollows:
Selvedge Portions
warp cord: same as in EXAMPLE I
warp density: same as in EXAMPLE I
width o each
selvedge portion: 12.7 mm
Body Portion
warp cord: same as in EXAMPLE I
warp density same as in EXAMPLE I
From the above it is apparent that the warp cords
in the selvedge portions have a degree of twist equal to
four times the degree of twist of the warp cords in the body
portion.
A number of pieces of fabric were cut off the
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roll of in-termedlate materlal as described in EXAMPLE I but,
were not spliced together selvedge -to selvedge as described
in EXAMPLE I. Instead these pieces (pieces A i.e. Al, A2,
etc.) were used to make new pieces (pieces ~ i.e. Bl, B2,
etc.) each having a length as required for the particular
size of tire. The new pieces B were prepared as follows:
(1) a first new piece,(Bl) was cut off from piece Al at the
required length; (2) the remaining portion of piece Al was
spliced to piece A2, the cut off edge overlapping a selvedge
portion of piece A2; (3) a second new piece, s2, was cut off
the joined material such that piece B2 contained the splice;
(4) the remaining portion of piece A2 was then spliced to
p:Lece A3 and the procedure was repeated to produce a number
of pieces B most of which contained a splice. The width of
each splice was 12.7 mm.
New pieces B were used for the carcasses of
radial tires as follows:
Tire size: P 195-75 R 14 (radial construction)
Carcass Ply: monoply
Testing and inspection of two of the above tires
each conta:Lning tire cord fabric according to the present
inve~ntion with a selvedge portion to body portion splice
reve:aled that:
~1) the uniformity of the tires wa~ considered
to be acceptable after visual inspection by persons
experienced in the manufacture of radial tires.
(2) the splice indentations in the sidewalls of
the tires were also acceptable ranging in depth from 18
units to 23 units on a scale in which 25 units or less is
rated acceptable; this scale of measurement being different
from that used in EXAMPLE I.
EXAMPLE III
An intermediate material having two selvedge
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portions and a body portion was made, rubberized and wound
up as a roll. Some characteristics of the roll of
intermediate material were as follows:
Selved~e Portions
warp cord: nylon 66 cord of 1880 dtex formed from two
940 dtex nylon 66 yarns, each having a
twist of 4.7 turns/cm in the same twist
direction, by combining and twisting the
two yarns together at 4.7 turns/cm in the
opposite twist direction to produce cord
with a degree of twist of 4.7 turns/cm.
warp cord
diameter: 0.53 mm
warp density: 11 cords/cm
width of
selvedge portion: 10 mm
Body Portion
warp cord: same as in EXAMPLES I & II
warp cord
diameter: 0.625 mm
warp denstiy: same as in EXAMPLES I & II
From the above it is apparent that the warp cords
in the selvedge portions have a degree of twi~t equal to 4.7
times the degree of twist of the warp cords in the body
portion and that the warp cords in the selvedge portions
have a diamenter equal to 85% of the diameter of the warp
cord~ in the body portion.
A number of pieces of fabric of length sufficient
to run from bead to bead of a particular size of tire and to
provide for the required "turn ups" were cut off the roll of
intermediate material at an angle of 90 to the direction of
the warp cords. These pieces of fabric (pieces A) were used
to make new pieces (pieces B) each having a length as
required for the particular size of tire as described in
EXAMPLE II. The width of each splice was 10 mm.
The new pieces B were used for the carcasses of
radial tires as follows:
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Tire Size: FR 78-14 (radial construction)
Carcass Ply: monoply
Tests on two of the above tires each containing
tire cord fabric of the present invention with a selvedge
portion t:o body portion splice revealed that:
(1) the uniformity of the tires was acceptable
as indicated by radial load variation measurements.
(2) the splice indentations in the sidewalls of
the tires were also acceptable ranging from 0.20 mm to
0.30 mm in depth when the tires were inflated to 275 kPa.
EXAMPLE IV
As a comparison, an intermediate material having
two selvedge portions and a body portion was made,
rubberized and wound up as a roll. The characteristics of
the roll of intermediate material were the same as described
in ~SXAMPLE I except that the same tire cord was used as warp
cord in selvedge portions as in the body portion. These
characteristics were as follows:
Sel~redge Portion
wl~rp cord: same as in EXAMPLE I, degree oE twist of
four turn~/cm
wl~rp density: 11 cords/cm (same as in EXAMPLE I)
wLdth oP each
selvedge portion: 10 mm (same as in EXAMPLE I)
Body Portion
warp cord: Same as in selvedge portion (see above),
degree of twist of four turns/cm
warp density: 11 cords/cm (same as in selvedge portion)
From the above it is apparent that the warp cords
in the selvedge portions have a degree of twist the same as,
i.e. one times the degree of twist of the warp cords in the
body portion.
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A number of pieces of fabric were cut off the
roll of intermediate ma-terial a~ describ~d in FIXAMPLE I.
These pieces of fabric were then spliced together as
described in EXAMPLE I. The width o~ each splice in the new
roll of fabric was 10 mm.
Lengths were cut from the roll of new fabric and
used for the carcasses of radial tires as follows:
Tire size: ER78-l4 (radial construction)
Carcass Ply: monoply
Tests on two of the above tires each containing
tire cord ~abric with a selvedge portion to selvedge portion
splice, but outside the scope of the present invention
revealed that:
(1) non-uniformities in the tires were apparent
as indicated by the radial load variation of tires being two
times that of the tires produced in EXAMPLES I and III.
(2) the splice indentations in the sidewalls of
the tires were unacceptable ranging from 0.61mm to 0.69 mm
in depth when the tires were inflated to 275 kPa.
EXAMPLE V
As a further comparison, an intermediate material
having two selvedge portions and a body portion was made,
rubberizecl and wound up as a roll. The characteristics of
the roll of intermediate material were the same as described
in EXAMPLE II except that the same tire cord was used as
warp cord in the selvedge porti.ons as in the body portion.
These characteristics were as follows:
Selvedge Portion
warp cord: same as in EXAMPLES I & II, degree
of twist of four turns/cm
warp density: 11 cords/cm
width of eac!h
35 selvedge porti.on: 12.7 cm
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Body Portion
warp cord: same as in selvedge portion
warp density: 11 cords/cm
From the above it is apparen-t that the warp cords
in the selvedge portions have a degree of twist the same as,
i.e. one times the degree of twist of the warp cords in the
body portion.
A number of pieces of fabric were cut off the
roll of intermediate material as described in EXAMPLE II. A
number o~ these pieces of fabric were then spl.iced together.
The width of each splice in the new fabric was 12.7 mm.
Lengths of new fabric were used for the carcasses
o radial tires as follows:
Tire size: FR78-14
Carcass Ply: monoply
Tests on two of the above tires each containing
tire cord fabric with a selvedge portion to body portion
splice, but outside the scope of the present invention
revealed that:
(1) non-uniformit.ies in the tires were apparent
as indicated by indentations visible in the sidewall rated
objectionable by persons experienced in radial tire
manuEacture.
(2) The splice indentations in the sidewalls of
the tires were unacceptable and in excess of S0 units in
depth on a scale in which 25 units or :less is rated
acceptable; this measurement scale being different from that
used in EXAMPLES I., III and IV.
