Note: Descriptions are shown in the official language in which they were submitted.
212~6~!~
The present invention relates to a heat-resistant,
laminated conveyer belt and more particularly to a heat-
resistant, laminated conveyer belt used in conveying all
flat materials such as cardboard, resin made tile, and to
its manufacturing method.
In the past, as a conveyer belt used in conveying
flat materials, e.g., paper and cardboard, there has
been known a conveyer belt in which two to six belts
base materials of the same type are laminated through a
PFA fluorocarbon resin film, and the conveyer belt made
up of two or more layers of belt base materials has been
used according to the strength required for its applica-
tion.
FIG. 4 shows a conventional conveyer belt. This
conveyer belt is formed by sandwiching a PFA fluorocar-
bon resin film 43 between heat-resistant fiber cloths 41
and 42. The heat-resistant fiber cloths are woven
cloths made of glass fiber, carbon fiber, aramid fiber
and aromatic allylate fiber, and they are also woven in
the form of plain weave, satin weave and twill weave.
Moreover, the heat-resistant cloth is impregnated on, at
least, one side of the surface with TFE fluorocarbon
resin, dried, and sintered, and it follows that this
composite possesses exceptional properties, that is,
high chemical resistance, heat resistance, ant-stick
proerty, and wear resistance. Furthermore, in some
cases, an one-layer belt is used under high tension.
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However, normally, the conveyer belt, which is made up
of two or more layers, is used.
However, when two above-mentioned fluoroplastic
composites with the heat-resistant cloths of the
sameweave are thermally pressurized, thereby obtaining a
two-layer belt, the upper layer (hereinafter called "the
wear-resistant layer") cannot follow the expansion and
contraction of the lower layer (hereinafter called "the
reinforcing layer") because of the difference in the
circumferential length between the wear-resistant layer
and the reinforcing layer. As a result, a surface
separation occurs between the heat-resistant fiber
cloths and the impregnated fluoroplastic layer inside
the wear-resistant layer by the shearing stress of the
surface between the reinforcing layer and the wear-
resistant layer and/or the shearing stress of the wear-
resistant layer itself. Due to this, there is a problem
in that the original properties of fluoroplastic are
lost and the lifetime of the belt is shortened.
An object of the present invention is to provide a
heat-resistant, laminated conveyer belt which has the
long lifetime without losing the original fluoroplastic
properties by comprising a wear-resistant layer with the
good flexibility, which is obtained by impregnating
fluoroplastic into a base cloth formed by weaving heat-
resistant fiber in the form of a knit weave, drying and
sintering the base cloth, on a reinforcing layer.
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Moreover, other object of the present invention is
to provide the method for manufacturing a heat-
resistant, laminated conveyer belt, which has the a
lifetime without losing the original fluoroplastic pro-
perty, by comprising the steps of obtaining a rein-
forcing layer by impregnating fluoroplastic into a
heat-resistant fiber base cloth, drying and sintering
the base cloth and obtaining a wear-resistant layer
formed on the reinforcing layer, by impregnating
fluoroplastic into a base cloth formed by weaving heat-
resistant fiber in the form of a knit weave, drying and
sintering the base cloth.
According to the present invention, there can be
obtained a heat-resistant, laminated conveyer belt
comprising a reinforcing layer obtained by impregnating
fluoroplastic into a heat-resistant fiber base cloth,
drying and sintering the base cloth; and a wear
resisting layer, formed on the reinforcing layer,
obtained by impregnating fluoroplastic into a base cloth
formed by weaving heat-resistant fiber in the form of a
knit weave, drying and sintering the base cloth.
Also, according to the present invention, there can
be obtained a method for manufacturing a heat-resistant,
laminated conveyer belt comprising the steps of
obtaining an reinforcing layer by impregnating
fluoroplastic into a heat-resistant fiber base cloth,
drying and sintering the base cloth; and obtaining
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a wear-resistant layer, formed on the reinforcing layer,
by impregnating fluoroplastic into a base cloth formed
by weaving heat-resistant fiber in the form of a knit
weave, drying and sintering the base cloth.
This invention can be more fully understood from
the following detailed description when taken in con-
junction with the accompanying drawings, in which:
FIG. lA is a plan view of a heat-resistant, lami-
nated conveyer belt of one embodiment of the present
invention;
FIG. lB iS a cross sectional view taken along
a line of X-X of FIG. lA;
FIG. 2 is a view explaining a knit weave according
to the present invention;
FIG. 3 iS a view explaining a running test of the
heat-resistant conveyer belt of FIG. lA; and
FIG. 4 is a view explaining a conventional layer
belt.
In the present invention, as a heat-resistant fiber
cloth, there can be used glass fiber, carbon fiber,
aramid fiber, aromatic allylate fiber. Particularly,
glass fiber or aramid fiber is desirably used.
As fluoroplastic, there can be used poly-
tetrafluoroethylene ( PTFE), polytetrafluoroethylene-per-
fluoroalky vinyl ether copolymer (PFA),
tetrafluoroethylene hexafluoropropylne copolymer ( FEP)
in a single form or a form of mixture of two or more
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kinds. Also, heat-resistant filler may be mixed into
fluoroplastic in order to much improve wear resistance
of the wear-resistant layer.
As the weaving method of the woven cloth, there are
a plain weave, a satin weave, twill weave, and a knit
weave. When the composite materials, which are obtained
by impregnating fluoroplastic into the woven cloth of
the same weaving method, drying and sintering the woven
cloth, are laminated in a two-layer belt shape through a
PFA film by thermal pressurization, a surface separation
occurs particularly between the heat-resistant fiber
cloths and fluoroplastic layer of the wear resistant
layer because of the shearing stress caused by a dif-
ference in a circumferential length between the rein-
forcing layer and the wear-resistant layer.
Therefore, according to the present invention, in
the case of the two-layer belt shape, as compared with
the same weaving method, that is, the combinations of
the reinforcing layer cloth and the wear-resistant layer
cloth such as the plain wave - plain weave, the plain
weave - satin weave, and the twill weave - twill weave,
the combinations of the reinforcing layer cloth and the
wear-resistant layer cloth such as the plain wave - knit
weave, the satin weave - knit weave, and the twill
weave - knit weave, are preferable. FIG. 2 is a view
explaining the knit weave using a knit weaving material
21.
21 246S9
In the present invention, the non-woven fabrious
mat, which is made up of heat-resistant, corrugated
short fiber or heat-resistant spring-shaped short fiber
itself, is also preferably used as the base material of
the wear-resistant layer. In that case, the wear-
resistant layer is formed in accordance steps: the above
mentioned mat is pregnated with fluoroplastic then dried
and sintered.
In the present invention, the content of
fluoroplastic in the reinforcing layer is 80 weight% or
less, preferably 30 to 60 weight%. If the content of
fluoroplastic exceeds 80 weight%, there is possibility
that the flexibility of the conveyer will be lost. If
the content of fluoroplastic is below 30 weight%, there
is possibility that bowed filling will occur in the
woven cloth. On the other hand, the content of
fluoroplastic in the wear-resistant layer is 80 weight%
or less, preferably 30 to 60 weight%. If the content of
fluoroplastic exceeds 80 weight%, the wear-resistant
layer cannot follow the expansion and contraction of the
reinforcing layer which the present invention intends.
As a result, the~ability of expansion and contraction
and flexibility will be lost. If the content of
fluoroplastic is below 30 weight%, there is possibility
that wear of the knit weave itself will be promoted and
that the maintenance of the shape of the knit weave
itself will be lost.
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According to the present invention, the heat-
resistant fiber of the wear-resistant layer is formed
into a knit weave or a corrugated or spring-shaped non-
woven cloth, thereby providing the ability of expansion
and contraction for wear-resistant layer. Therefore,
flexibility of the wear-resistant layer can be extremely
improved as compared with the conventional layer belt,
which is manufactured by the same weave structure, so
that the lifetime of the belt can be improved.
An embodiment of the present invention will be
explained with reference to FIGS. lA and lB.
FIG. lA is a plan view of a heat-resistant, lami-
nated conveyer belt, and FIG. lB is a cross sectional
view taken along a line of X-X of FIG. lA.
A reinforcing layer 11 having a thickness of 0.5 mm
is formed by impregnating PTFE fluorocarbon resin into a
heat-resistant fiber base cloth, and drying and sin-
tering the base cloth. More specifically, the rein-
forcing layer 11 can be obtained by the following
process.
A woven cloth is formed by weaving aromatic aramid
fiber (trade name: Technora manufactured by Teijin Co.,
Ltd.) in the form of the plain weave. PEFE fluorocarbon
resin dispersion (trade name: Teflon T-30J, manufactured
by Mitsui-Du Pont Fluoro Chemical Co., Ltd) is
impregnated into the woven cloth. Then, the woven cloth
is dried, and sintered at 380C. This process is
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repeated several times, thereby the reinforcing layer 11
can be obtained.
The wear-resistant layer 12 having a thickness of
0.5 mm is formed on the reinforcing layer 11 through a
PFA film 13 having a thickness of 25~m. More speci-
fically, the wear-resistant layer 12 can be obtained by
the following process.
A woven cloth is formed by weaving aramid fiber
(trade name: Technora manufactured by Teijin Co., Ltd.)
in the form of the knit weave. PEFE fluorocarbon resin
dispersion (trade name; Teflon T-30J, manufactured by
Mitsui-Du Pont Fluoro Chemical Co., Ltd) is impregnated
into the woven cloth. Then, the woven cloth is dried,
and sintered at 380C. This process is repeated several
times, thereby the wear-resistant layer 12 can be
obtained.
The PFA fluorocarbon resin film 13 is sandwiched
between the reinforcing layer 11 as a lower layer and
the wear-resistant layer 12 as an upper layer. Then,
these laminated layers are thermally pressurized at
380C under pressure of 0.98 MPa. Then, both ends of
the obtained belt-shaped material are butt jointed to
each other to be endless.
As mentioned above, a heat-resistant, laminated
conveyer belt 14 comprises the reinforcing layer 11,
which is obtained by impregnating PTFFE fluorocarbon
resin into the aromatic aramid fiber base cloth, drying
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and sintering the base cloth, and the wear-resistant
layer 12, which is formed on the reinforcing layer 11
through the PFA fluorocarbon resin film 13 and which is
obtained by impregnating PTFFE into the base cloth,
which is formed by weaving aramid fiber in the form of
the knit weave, drying and sintering the base cloth to
provide the ability of expansion and contraction.
Therefore, flexibility of the obtained conveyer belt 14
can be extremely improved as compared with the conven-
tional laminated belt, which is manufactured by the same
weave structure, so that the lifetime of the belt can be
improved.
Actually, the running test of the conveyer belt 14
of the above-mentioned embodiment was performed in
accordance with the following conditions so as to exa-
mine the flexibility.
The conveyer belt 14 was set as shown in FIG. 3 by
use of drive rolls 31 and 32, pulleys 33, 34, and a load
pressure roll 35. Then, the conveyer belt 14 was run
under conditions of ambient temperature of 180C, load
of 1.5 kN/cm width and belt running speed of
800 m/minutes.
As a result of the running test, the number of
times at which the conveyer belt was brokendown was
49,856. On the other hand, regarding the layer belt
having the same structure as the above embodiment except
the point that the woven cloth of the wear-resistant
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layer was formed in the form of the plain weave, the
above-mentioned number of times was examined. As a
result, the number of times was 465. Therefore, it is
clear that the present invention is superior to the con-
ventional belt conveyer.
As mentioned above, according to the present inven-
tion, there is obtained a belt heat-resistant, laminated
conveyer which can has the long lifetime without losing
the original fluoroplastic properties on the ground that
the wear-resistant layer has the excellent ability of
expansion and contraction, that is, the excellent flexi-
bility.