JP2008156111A - Molded belt prevented from being warped and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the warpage of a molded belt due to the shrinkage of a vulcanized rubber layer after vulcanizing and molding. <P>SOLUTION: This molded belt 70 comprises a shrunk canvas 180 and a vulcanized rubber layer 181. The shrunk canvas 180 is formed by heating a non-shrunk canvas formed of synthetic resin fibers and heat-shrinkable in the lateral direction of a belt to a predetermined temperature or higher and shrinking it in a vulcanizing and molding step. The vulcanized rubber layer 181 is provided by heating and vulcanizing an unvulcanized rubber sheet in the vulcanizing and molding step. The difference between the lateral shrinkage rate of the unshrunk canvas and the rubber expansion rate of the vulcanized rubber layer 181 is within 2%, or the lateral shrinkage rate is higher than the rubber expansion rate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a molded belt with reduced warpage in the width direction and a method for manufacturing the molded belt.

  Conventionally, a conveying flat belt constructed by laminating a canvas on a vulcanized rubber layer is widely known. As a method for producing this belt, a so-called one-pot vulcanization molding apparatus is used, and the canvas and the vulcanized rubber are used. It is known to integrally vulcanize the layers. In general, a flat belt for conveyance manufactured by this method is significantly warped in the width direction of the belt.

  As another flat belt manufacturing method, there is known a method in which a plurality of long rubber layers individually vulcanized and molded are bonded together, and end portions thereof are joined together to form a belt. In this method, since the rubber layer is bonded to the vulcanized belt, it is not affected by the shrinkage and expansion of each material as in the case of integral molding, and the belt is not warped. However, since the belt ends are joined together with an adhesive or the like, the wearability and hardness of the seam portion is different from other portions, so there is a problem in belt performance and multiple processes are required, so efficiency There are also problems in workability and workability.

As a method for preventing the warpage of a belt manufactured by integral vulcanization molding, as described in Patent Document 1, the conveyor belt is made of a three-layer structure and both outer surfaces of the three layers are made of the same material. It has been known. As another method for preventing the occurrence of warping, as described in Patent Document 2, an outer layer mainly composed of a polyimide resin and containing a conductive substance and having a relatively low surface resistance value, and polyimide In a seamless belt mainly composed of a resin and having an inner layer having a relatively high surface resistance value, it is known that the linear expansion coefficient of the inner layer is larger than that of the outer layer.
JP 2002-12334 A JP 2002-365927 A

  However, the method described in Patent Document 1 has a problem in that applicable applications are limited because the layer structure of the belt is limited. Further, as disclosed in Patent Document 2, the method of controlling the amount of warpage by adjusting the linear expansion coefficient of each layer is such that the linear expansion coefficient of the canvas and the rubber layer is extremely large for a belt composed of the canvas and the rubber layer. It is different and cannot be applied.

  The present invention has been made in view of the above problems, and an object of the present invention is to suppress warpage in the width direction in a molded belt configured by laminating a rubber layer and a canvas.

  The inventors examined the cause of warping when a molded belt formed by laminating a rubber layer and a canvas was manufactured by integral vulcanization molding. In a conventional molded belt, It was found that the thermal expansion of the canvas is smaller than the thermal expansion coefficient of the rubber layer. It was also discovered that the canvas was shrunk before vulcanization of the rubber layer, and that the warp could not be prevented because the rubber layer further expanded and vulcanized after the shrinkage of the canvas. Then, in the cooling process after molding, the rubber layer tries to shrink in the width direction by the amount of thermal expansion, but the canvas hardly shrinks, and it has been found that warping occurs in the molding belt due to this difference in shrinkage. It was.

  Therefore, the inventors used a non-shrinkable canvas that can be thermally shrunk in the molded belt, and positively shrunk the canvas in the vulcanization molding process to cause the warp of the belt due to the shrinkage of the rubber layer. Reduced.

  That is, the molded belt according to the present invention is a laminate in which an unshrinkable canvas that is formed from synthetic resin fibers and is heat-shrinkable in the belt width direction and an unvulcanized rubber layer formed from unvulcanized rubber are laminated. As a result, the unshrinked canvas is heat-shrinked in the belt width direction to become a shrunk canvas, and the unvulcanized rubber layer is vulcanized to become a vulcanized rubber layer. This is a molded belt obtained by integrally molding a rubber layer. When the laminate is heated, at least the unshrinked canvas is heated to a predetermined temperature or higher, and when the laminate is heated to a predetermined temperature, the shrinkage in the width direction in the belt width direction of the unshrinked canvas and the vulcanized rubber layer The difference from the rubber expansion coefficient is within 2%, or the width direction shrinkage ratio is higher than the rubber expansion coefficient.

  The width direction shrinkage rate is preferably higher than the rubber expansion rate. The width direction shrinkage rate is, for example, 3 to 9%, and the rubber expansion rate is, for example, 0 to 6%. Moreover, it is preferable that the longitudinal shrinkage in the longitudinal direction of the belt of the unshrinked canvas is lower than the shrinkage in the width direction.

  The belt manufacturing method according to the present invention includes a laminate in which a non-shrinkable canvas formed of synthetic resin fibers and thermally shrinkable in the belt width direction and an unvulcanized rubber layer formed of unvulcanized rubber are laminated. The unvulcanized rubber layer is vulcanized and expanded to form a vulcanized rubber layer, and the unshrinked canvas is shrunk in the belt width direction to form a shrunk canvas, and the vulcanized rubber layer is shrunk. A vulcanization molding process for integrally molding a finished canvas and obtaining a belt slab, and cooling the belt slab and cutting it to a predetermined width, whereby the expanded vulcanized rubber layer was contracted in the width direction of the belt, A cooling step for obtaining a molded belt. In the vulcanization molding step, at least the unshrinked canvas is heated to a predetermined temperature or more, and the warp in the width direction of the molded belt due to the shrinkage of the vulcanized rubber layer is reduced by the shrinkage of the unshrinked canvas in the belt width direction. Let Here, the difference between the widthwise shrinkage in the belt width direction of the unshrinked canvas and the rubber expansion rate of the vulcanized rubber layer when heated to a predetermined temperature is within 2%, or the widthwise shrinkage rate is the rubber expansion rate. Set higher.

  In the vulcanization molding step, it is preferable to sandwich the laminate from the non-shrinkable canvas side and the unvulcanized rubber layer side. For example, at least an unshrinkable canvas and an unvulcanized rubber layer are wound around the outer peripheral surface of a columnar inner mold in this order, and a cylindrical laminate is mounted on the inner mold, and the outer mold is surrounded by the inner mold on which the stacked body is mounted. In the vulcanization molding step, the laminate is preferably clamped by the inner mold and the outer mold.

  The vulcanization molding step includes a first heating step of heating the laminated body at a first temperature from the non-shrinkable canvas side and the rubber layer side, and a second step, wherein the laminated body is different from the first temperature from the non-shrinkable canvas side. It is preferable that the 2nd heating process heated at this temperature is included, and the said 2nd temperature is higher than predetermined temperature.

  As described above, in the molding belt integrally formed with the rubber layer and the canvas, during the vulcanization molding process, the canvas is actively contracted, and the contraction rate is approximated to the expansion rate of the rubber layer. Since the warpage in the width direction of the molding belt due to the thermal expansion of the rubber layer can be reduced, a molding belt with a small amount of warpage can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a molding belt 70 according to the first embodiment. The molding belt 70 is, for example, an endless flat belt used for conveyance. The molding belt 70 is configured by vulcanizing and bonding a contracted canvas 180 to the lower surface of the vulcanized rubber layer 181. The molding belt 70 is used by being wound around a pulley so that the lower surface side of the contracted canvas 180 is in contact with a pulley (not shown), and the upper surface of the vulcanized rubber layer 181 serves as a conveying surface for conveying an object to be conveyed. .

  In the molding belt 70, a laminate 30 (see FIG. 3) in which an unvulcanized rubber sheet 81 (see FIG. 3) described later and an unshrinked canvas 80 (see FIG. 3) are laminated is pressed and heated. As a result, the unshrinked canvas 80 is thermally shrunk to become a shrunken canvas 180, the unvulcanized rubber sheet 81 is vulcanized to become a vulcanized rubber layer 181, and the shrunken canvas 180 and the vulcanized rubber layer 181 are It is obtained by molding integrally. In addition, when the laminated body 30 is heated by vulcanization molding, the contracted canvas 180 is contracted by being heated to at least a predetermined temperature T (for example, 160 ° C.).

The rubber component of the vulcanized rubber layer 181 includes nitrile rubber, chloroprene rubber, polybutadiene rubber, EPDM (ethylene-propylene-diene copolymer), hydrogenated nitrile rubber, styrene butadiene rubber, fluorine rubber, silicon rubber, natural rubber, And at least one selected from polyurethane rubber is used. The vulcanized rubber layer 181 expands by heating, and the volume expansion coefficient (hereinafter referred to as “rubber expansion coefficient”) of the vulcanized rubber layer 181 when the vulcanized rubber layer 181 is heated from 25 ° C. to a predetermined temperature T (for example, 160 ° C.). E _T ") is, for example, 0 to 6%. Note that the rubber expansion coefficient E _T is that of the vulcanized rubber layer 181 at the predetermined temperature T with respect to the volume of the vulcanized rubber layer 181 at 25 ° C. when the vulcanized rubber layer 181 is heated from 25 ° C. to the predetermined temperature T. The volume increase rate is expressed in%. Details of the method for measuring the rubber expansion coefficient will be described in Examples.

  Next, the manufacturing method of the shaping | molding belt which concerns on 1st Embodiment is demonstrated using FIG. FIG. 2 shows a vulcanization molding apparatus 10 used in this embodiment. The vulcanization molding apparatus 10 includes an inner mold 20 and an outer mold 40 that houses the inner mold 20 therein. The outer die 40 formed in a substantially cylindrical shape is provided with a substantially cylindrical rubber jacket 43 inside, and a sealed space 54 is formed between the rubber jacket 43 and the inner peripheral surface 72 of the outer die 40. The inside of the rubber jacket 43 is formed as a storage chamber 67 for storing the inner mold 20. As shown in FIG. 3, an inner mold 20 in which an unshrinked canvas 80 and an unvulcanized rubber sheet (unvulcanized rubber layer) 81 are wound around the storage chamber 67 is arranged in this order.

  The unvulcanized rubber sheet 81 in this embodiment is vulcanized and molded as described above, and becomes a vulcanized rubber layer 181 in the molded belt 70 (see FIG. 1).

  The unshrinked canvas 80 is formed by weaving or knitting synthetic resin fibers, for example, and for example, a first thread extending in the axis X direction of the inner mold 20 (that is, the width direction of the belt), and the inner mold 20 It is woven by a second yarn extending in the circumferential direction (that is, the longitudinal direction of the belt). For example, a warp as a woven structure is used for the first yarn, and a weft is used for the second yarn.

  In the non-shrinkable canvas 80, the first yarn extending in the axial direction X is a heat-shrinkable one, for example, one having a dry heat shrinkage at 120 ° C. of 3 to 35%, preferably 15-20% is used. The dry heat shrinkage rate is measured based on JIS L1042.

  The yarn used for the canvas of the conventional molding belt is heat-treated in advance, and heat shrinkage due to heating in the vulcanization molding process is suppressed. However, as the first yarn used in the present embodiment, for example, a yarn that has not been heat-treated is used, and the heat shrinks relatively greatly by heating in the vulcanization molding process.

  The second yarn is, for example, a yarn that has been heat-treated in advance and is not substantially thermally contracted in the vulcanization molding process, and has a lower thermal shrinkage rate at the belt vulcanization temperature than the first yarn. The fiber used for the first and second yarns is not particularly limited, and is, for example, PET, PBT, or PTT.

By using the first yarn as described above, the non-shrinkable canvas 80 in the present embodiment is a canvas that is sufficiently shrunk in the width direction of the belt by heating, and from 25 ° C. to a predetermined temperature T (for example, The shrinkage ratio (width direction shrinkage ratio W _T ) when heated to 160 ° C. is 3% or more, and is preferably set to 3 to 9%. Meanwhile, since the second yarn yarn low shrinkage is used, the belt longitudinal shrinkage of unshrunk canvas 80 (hereinafter, referred to as longitudinal shrinkage rate L _T), from the width direction shrinkage W _T Lower. The method of measuring the width direction shrinkage W _T, along with detailed in Example, longitudinal shrinkage rate L _T is measured in the same conditions as the width direction shrinkage W _T.

Further, unshrunk fabric 80, during high temperature heating, Significant shrinkage than in the low-temperature heating, the width direction shrinkage W _T when heated to a predetermined temperature (160 ° C.) from 25 ° C., at 120 ° C. from 25 ° C. more than twice the width direction shrinkage W ₁₂₀ when heated.

Unshrunk fabric 80 is used higher than the conventional fabric width direction shrinkage W _T, thereby, the difference between the rubber expansion ratio E _T of the vulcanized rubber layer 181 is, for example, within 2%, or elevated It is set high from the rubber expansion ratio E _T of the vulcanized rubber layer 181. And, preferably, the width direction shrinkage W _T is higher than the rubber expansion ratio E _T, the difference is set to within 3%. The width direction shrinkage W _T, is a rubber expansion ratio E _T by being set in this way, molded belts 70 warp is small can be obtained. The molding belt 70 with less warpage is excellent in flatness and has a good transport function.

  Next, the vulcanization molding method of the laminated body 30 in this embodiment will be described with reference to FIGS. In the present embodiment, in a state where the inner mold 20 is housed in the outer mold 40, the pressure medium heated to the initial temperature t0 is supplied to the sealed space 54 provided in the outer mold 40, and the rubber jacket 43 is The laminated body 30 is expanded radially inward, and the laminated body 30 is pinched by the rubber jacket 43 and the inner mold 20 to be urged with a predetermined pressure. The supply of the pressure medium at the initial temperature t0 is continued in the period m0, and the air existing between the rubber jacket 43 and the inner mold 20 is pushed out of the storage chamber 67. Further, in the period m0, the heat medium having the initial temperature t0 is also supplied into the inner mold 20, that is, the laminate 30 is heated at the initial temperature t0 from the outer peripheral surface 27 of the inner mold 20 and the inner peripheral surface of the outer mold 40. Is done. Since the initial temperature t0 does not reach the temperature at which the unvulcanized rubber sheet 81 is vulcanized, that is, the vulcanization temperature, the torque indicating the degree of vulcanization of the unvulcanized rubber sheet slightly increases during the period m0. Just do it.

  The torque indicating the degree of vulcanization is a torque measured when torsional vibration is applied to the rubber sheet 81 at each time. In FIG. 4 and FIGS. C is indicated by a solid line. On the other hand, the temperature transition is indicated by a dotted line. Note that a constant pressure is continuously applied to the laminate 30 over the period m0 to the period m2 due to the sandwiching pressure between the inner mold 20 and the outer mold 40.

  After the elapse of the period m0, the temperature of the pressure medium is increased from the initial temperature t0 to the first temperature t1 in the period m1. Similarly, the heat medium supplied into the inner mold 20 is also raised to the first temperature t1 during the period m1. Due to the pressure medium and the heat medium heated to the first temperature t1, the laminated body 30 causes the inner peripheral surface of the rubber jacket 43 (that is, the unvulcanized rubber sheet 81 side) and the outer peripheral surface 27 of the inner mold 20 (that is, uncontracted). The heating is performed from the canvas 80 side, and this heating is continued for a period m2, as shown in FIG.

  The unvulcanized rubber sheet 81 is thermally expanded by heating in the periods m0 to m2, and the laminate 30 is vulcanized and molded, and the curast curve C of the unvulcanized rubber sheet 81 rises as the heating temperature rises. Then, the rise of the curast curve C is substantially terminated when a predetermined time has elapsed during the period m2. That is, in the laminate 30, the vulcanization of the unvulcanized rubber sheet 81 is completed in the period m 2, and the unshrinked canvas 80 is vulcanized and bonded to the unvulcanized rubber sheet 81, so that the vulcanized rubber layer 181 (see FIG. 1). ) And the contracted canvas 180 (see FIG. 1) are integrally formed. The first temperature t1 is a temperature equal to or higher than the predetermined temperature T described above.

  When the heating in the period m <b> 2 is completed, the supply of the heat medium and the pressure medium to the inner mold 20 and the outer mold 40 is stopped and the inner mold 20 is taken out from the storage chamber 67. The extracted inner mold 20 is cooled to, for example, room temperature (about 25 ° C.) together with the belt slab, and the belt slab having a substantially cylindrical shape is separated from the inner mold 20 and then cut along the circumferential direction. A molding belt 70 having the following is obtained. As described above, the molding belt 70 is an endless flat belt configured by closely shrinking the contracted canvas 180 on the lower surface of the vulcanized rubber layer 181.

In the present embodiment, the second temperature t1 is set to be higher than the predetermined temperature T, and the vulcanized rubber layer 181 is heated to the predetermined temperature T or higher at the end of vulcanization. 181 is inflated equivalent rubber expansion ratio E _T, or more than the rubber expansion ratio E _T. Therefore, when the vulcanized rubber layer 181 is cooled, it is expanded in the circumferential direction (belt longitudinal direction), axial direction (belt width direction), and radial direction (belt thickness direction). A force (shrinking force) for contracting is applied.

  On the other hand, as described above, the unshrinked canvas 80 is a canvas that heat-shrinks in the direction of the axis X, and is shrunk at a predetermined shrinkage rate in the direction of the axis X during the vulcanization molding period m0 to m2. The finished canvas 180 is obtained. However, the contracted canvas 180 is not substantially expanded and contracted when cooled from the first temperature t1 to room temperature (25 ° C.). Therefore, a force (shrinkage force) is applied to both ends of the laminated body 30 in the axis X direction from the non-shrinkable canvas 80 so as to warp radially inward due to the shrinkage of the non-shrinkable canvas 80 in the vulcanization molding process. The force is continuously applied to the belt slab even after being cooled.

  In general, when the belt slab is shortened by cutting the length in the width direction (axial direction) due to the contraction force of the vulcanized rubber layer 181, a concave warp occurs in the width direction. That is, when the belt slab is cut and shortened, the contraction force is released and is applied in the belt width direction, whereby a large warping force is applied in the belt width direction. This warping force is a force that warps upward both ends E in the width direction of the molding belt 70 in FIG.

However, in the present embodiment, the warping force generated by the shrinkage of the rubber sheet 81 is canceled out by the force (shrinking force) generated by the shrinkage of the non-shrinkable canvas 80 described above, thereby preventing the warpage in the width direction. Be made. Particularly in this embodiment, the predetermined temperature T of the contraction already fabric 180 (i.e., the temperature t1 the following temperature) shrinkage is high in the belt width direction, the width direction shrinkage W _T and vulcanized rubber layer of the unshrunk canvas 80 The difference from the rubber expansion coefficient E _{T of} 180 is set within 2%, or the width direction shrinkage ratio W _T is set higher than the rubber expansion coefficient E _T , and the occurrence of warpage is effectively suppressed.

Further, the unshrinked canvas 80 has a low width direction shrinkage ratio E ₁₂₀ at a low temperature (for example, 120 ° C.), and therefore when heated at a low temperature (less than the first temperature t1) in the period m1, the heat shrinkage amount is relatively large. small. However, the predetermined temperature T of the unshrunk fabric 80 (e.g., 160 ° C.) high thermal shrinkage ratio W _T in, unshrunk fabric 80, when it is heated above the predetermined temperature T in the period m2, is relatively large shrinkage It is done.

On the other hand, the unvulcanized rubber sheet 81 is vulcanized and bonded to the unshrinked canvas 80 in the period m1 as indicated by the curast curve C. That is, since the non-shrinkable canvas 80 is vulcanized and bonded to the rubber sheet 81, the non-shrinkable canvas 80 is greatly heat-shrinked, so that the shrinkage force of the non-shrinkable canvas 80 is effectively applied to the belt slab. In order to significantly prevent warping of the belt, shrinkage force of unshrunk fabric is preferably high, the width direction shrinkage W _T at a given temperature T of the unshrunk canvas 80 is higher than the rubber expansion ratio E _T Better.

  As described above, conventionally, when vulcanization molding of a laminate in which an unvulcanized rubber layer and a canvas are laminated, the unvulcanized rubber layer expands in vulcanization molding and then contracts when cooled. Due to the shrinkage, a concave warp occurred in the molded belt. However, in the present embodiment, the concave warpage can be reduced by positively heat-shrinking the canvas in the belt vulcanization molding step.

  Next, a second embodiment will be described. The difference between the second embodiment and the first embodiment is a method for heating the stacked body 30. Hereinafter, the heating method in the second embodiment will be described with reference to FIG.

  Similar to the first embodiment, the stacked body 30 is heated by the pressure medium and the heat medium having the initial temperature t0 supplied to the outer mold 40 and the inner mold 20 in the period m0. Then, after the period m0 ends, in the period m1, the pressure medium and the heat medium are raised to the first temperature t1. Note that a constant pressure is continuously applied to the stacked body 30 over the period m0 to the period m2 'by the sandwiching pressure between the inner mold 20 and the outer mold 40.

  The laminated body 30 has an inner peripheral surface (that is, the rubber sheet 81 side) of the rubber jacket 43 and an outer peripheral surface 27 (that is, the non-shrinkable canvas 80 side) of the inner mold 20 by the pressure medium and the heat medium heated to the first temperature t1. ) And this heating is continued for a period m2 as shown in FIG.

  Due to the heating in the periods m1 and m2, the degree of vulcanization of the rubber sheet 81 increases with the increase in the heating temperature (see the curast curve in FIG. 5), and the increase is substantially finished when a predetermined time elapses in the period m2. Be made. That is, in the laminated body 30, the vulcanization of the rubber sheet 81 is completed in the periods m1 and m2, and the contracted canvas 180 is vulcanized and bonded to the vulcanized rubber layer 181 to obtain a belt slab (not shown).

  After the elapse of the period m2, the temperature of the heat medium supplied to the inner mold 20 is raised to the second temperature t2, and the heat medium is maintained at the second temperature t2 in the period m2 '. On the other hand, in the period m2 ', the temperature of the pressure medium supplied to the sealed space 54 of the outer mold 40 is maintained at the first temperature t1. That is, in the period m2 ', the laminate 30 is heated from the inner mold 20 side at the second temperature t2 and is heated from the outer mold 40 side at the first temperature t1. Here, the second temperature is higher than the predetermined temperature T described above.

  After the period m <b> 2 ′ has elapsed, the supply of the heat medium and pressure medium to the inner mold 20 and the outer mold 40 is stopped, and the inner mold 20 is taken out from the storage chamber 67. The taken out inner mold 20 is cooled to, for example, room temperature (about 25 ° C.) together with a belt slab (not shown), and the belt slab (not shown) having a substantially cylindrical shape is removed from the inner mold 20 and then along the circumferential direction. Thus, a molding belt (flat belt) 70 having a predetermined width is molded.

Also in this embodiment, the non-shrinkable canvas 80 and the unvulcanized rubber sheet 81 are the same as those in the first embodiment, that is, the non-shrinkable canvas 80 is sufficiently heat-shrinked at a predetermined temperature T (for example, 160 ° C.). a canvas that is, the width direction shrinkage W _T of the unshrunk fabric 80, pressure difference between the rubber expansion ratio E _T of the vulcanized rubber layer 181 is within 2%, or the width direction shrinkage W _T is rubber higher than the inflation rate E _T is set.

  In the present embodiment, the unshrinked canvas 80 is heat-shrinked in the period m2, but, similarly to the first embodiment, the unshrinked canvas 80 has a relatively low shrinkage rate in the width direction during low-temperature heating. Unheated canvas 80 cannot be sufficiently contracted only by heating at m2.

  Therefore, in the present embodiment, the unshrinked canvas 80 is heated at the second temperature t2 higher than the first temperature t1 in the period m2 ′ after the period m2. Here, the second temperature t2 is higher than the predetermined temperature T described above, and the unshrinked canvas 80 is sufficiently shrunk in the period m2 '. That is, also in the present embodiment, the unshrinked canvas 80 is heated to at least the predetermined temperature T or higher, and thereby the unshrinked canvas is effectively thermally contracted.

  In the period m2 ', the heating temperature on the rubber sheet 81 side remains set at the first temperature t1, so that no excessive heat history is added to the rubber sheet 81. Similarly, in the present embodiment, since the canvas 81 is actively contracted during the period m2 ′, it is not necessary to contract the canvas 81 during the period m2, and therefore the temperature of the period m2 (first temperature t1) is set. Can be set low. Accordingly, since an extra heat history is prevented from being added to the unvulcanized rubber sheet 81 in the period m2, decomposition and extra expansion due to heating of the vulcanized rubber layer 181 are suppressed. Note that the first temperature t1 may be lower or higher than the predetermined temperature T.

  Further, in this embodiment, immediately after the start of the vulcanization molding process, as indicated by the curast curve C, the unvulcanized rubber sheet 81 is vulcanized and vulcanized and bonded to the unshrinked canvas 80, while vulcanized. In the latter half of the molding process, the unshrinked canvas 80 is greatly shrunk. In other words, in the present embodiment, the unshrinked canvas 80 is greatly shrunk after being vulcanized and bonded to the rubber sheet 81, so that the warpage of the laminate 30 is effectively reduced by the shrinkage of the unshrinked canvas 80. .

  The non-shrinkable canvas 80 is heated to the second temperature t2 in a short time because it is thin and has a relatively high thermal conductivity by heating in the period m2 '. However, the rubber sheet 81 (vulcanized rubber layer 181) is heated from the outer mold 40 at the first temperature t1 and is heated from the inner mold 20 side at the second temperature t2, but the thermal conductivity is low. Therefore, in the period m2 ′, a part is heated to the second temperature t2, but the whole is not heated to the second temperature t2.

That is, in this embodiment, the unshrinked canvas 80 is heated to a predetermined temperature T or higher, but the vulcanized rubber layer may not be heated to the predetermined temperature T at the end of heating. However, the rubber expansion coefficient of the vulcanized rubber layer 181 does not vary greatly depending on the temperature variation at the vulcanization temperature (for example, about 100 to 180 ° C.). Thus, a rubber expansion ratio E _T at a given temperature T of the vulcanized rubber layer 181, the difference between the width direction shrinkage W _T of the unshrunk fabric 80 to within 2%, or rubber expansion in the width direction shrinkage W _T if greater than E _T, also in this embodiment, it is possible to prevent warping of the molded belt.

  Next, a third embodiment will be described. Since the difference between the third embodiment and the first embodiment is only the heating method of the laminate 30, the heating method will be described below with reference to FIG.

  Similar to the first embodiment, the stacked body 30 is heated by the pressure medium and the heat medium having the initial temperature t0 supplied to the outer mold 40 and the inner mold 20 in the period m0. Note that a constant pressure is continuously applied to the laminate 30 over the period m0 to the period m2 due to the sandwiching pressure between the inner mold 20 and the outer mold 40.

  After the period m0 has elapsed, the temperature of the heat medium supplied to the inner mold 20 is raised to the second temperature t2, and the heat medium is maintained at the second temperature t2 in the period m2 '. On the other hand, the pressure medium supplied to the outer mold 40 is raised to the first temperature t1 in the period m1, and the temperature of the pressure medium is maintained at the first temperature t1 in the period m2 '. That is, in the period m2 ', the laminate 30 is heated from the inner mold 20 side at the second temperature t2 and is heated from the outer mold 40 side at the first temperature t1. Similar to the second embodiment, the first temperature t1 may be higher or lower than the predetermined temperature T. On the other hand, the second temperature t2 is set higher than the predetermined temperature T.

  When the period m2 ′ elapses, the temperature of the heat medium supplied into the inner mold 20 is lowered to the first temperature t1, and in the period m2, the heat medium supplied into the inner mold 20 and the outer mold 54 are supplied. The temperature of the pressure medium is set to the first temperature t1. As can be seen from the curast curve C, the increase in the degree of vulcanization substantially ends when a predetermined time elapses in the period m2, and the vulcanization of the rubber sheet 81 is completed in the period m2, and the inner mold A belt slab is formed on the outer peripheral surface of the belt 20.

  When the heating in the period m <b> 2 is completed, the supply of the heat medium and the pressure medium to the inner mold 20 and the outer mold 40 is stopped and the inner mold 20 is taken out from the storage chamber 67. The taken out inner mold 20 is cooled together with the belt slab to, for example, room temperature (about 25 ° C.), and the belt slab is detached from the inner mold 20 and then cut along the circumferential direction. 70 is obtained.

Also in this embodiment, the non-shrinkable canvas 80 and the unvulcanized rubber sheet 81 are the same as those in the first embodiment. That unshrunk fabric 80 is a fabric that is sufficiently heat shrink at the predetermined temperature T (e.g., 160 ° C.), and the width direction shrinkage W _T of unshrunk canvas 80, rubber expansion ratio of the vulcanized rubber layer 181 E _T the difference between the is within 2%, or the width direction shrinkage W _T is set higher than the rubber expansion ratio E _T. As in the first and second embodiments, the unshrinked canvas 80 having such a configuration is sufficiently heat-shrinked by being heated to a predetermined temperature or higher in the vulcanization molding process. Warpage is prevented from occurring.

  In the present embodiment, the non-shrinkable canvas 80 is positively heated to the second temperature t2 from the inner mold 20 side in the period m2 ′, so that the non-shrinkable canvas 80 can be sufficiently shrunk by the heating. . On the other hand, in the period m <b> 2 ′, the temperature on the outer mold 40 side is set to the first temperature t <b> 1 that is lower than the second temperature t <b> 1.

  In the second and third embodiments, the first temperature (vulcanization heating temperature) t1 is set to 120 to 170 ° C., for example, and the second temperature (canvas shrinkage temperature) t2 is set to 150 to 180 ° C. for example, The second temperature t2 is set higher than the first temperature t1. Further, the period (vulcanization period) m2 is set to 20 to 40 minutes, for example, and the period (canvas contraction period) m2 'is set to 3 to 10 minutes, for example, and is shorter than the period m2.

  The configuration of the molding belt 70 is not limited to the above-described configuration, and may have the configuration shown in the first to third modifications. FIG. 7 shows a molding belt 70 according to a first modification. As shown in FIG. 7, the molding belt 70 of the first modification includes a first canvas 180A, a second canvas 180B stacked on the upper surface of the first canvas 180A, and the upper surface of the second canvas 180B. The rubber layer 181 is laminated.

  When the molding belt 70 is manufactured, the first mold canvas, the second canvas, and the unvulcanized rubber sheet are wound around the inner mold 20 in this order. Here, at least one of the first and second canvases has the same configuration as the non-shrinkable canvas 80 in the present embodiment.

  FIG. 8 shows a second modification. As shown in FIG. 8, the molding belt 70 according to the second modified example includes a contracted canvas 180, a reinforcing layer 190 stacked on the upper surface of the contracted canvas 180, and a rubber layer stacked on the upper surface of the reinforcing layer 190. 181. The reinforcing layer 190 is configured by burying a core wire 192 extending in the longitudinal direction in the primer layer 191.

  When the molding belt 70 is manufactured, the inner mold 20 is first wound with an unshrinked canvas previously coated with a primer so that the surface coated with the primer faces the outer periphery. Next, a core wire is spirally wound on the primer, and an unvulcanized rubber sheet is further wound on the core wire. Here, the configurations of the rubber sheet and the non-shrinkable canvas are the same as those in the present embodiment. The primer is made of rubber or synthetic resin, and the rubber components are nitrile rubber, chloroprene rubber, polybutadiene rubber, EPDM (ethylene-propylene-diene copolymer), hydrogenated nitrile rubber, styrene butadiene rubber, fluorine rubber, silicon rubber. At least one selected from natural rubber and polyurethane rubber is used. As the synthetic resin, polyamide, polyurethane, vinyl chloride, phenol resin, polyimide, polyester, fluororesin, or the like is used.

  FIG. 9 shows a third modification of the present embodiment. As shown in FIG. 9, the molded belt 70 of the third modified example is laminated on the first canvas 180A, the reinforcing layer 190 laminated on the upper surface of the first canvas 180A, and the upper surface of the reinforcing layer 190. The second canvas 180B and the rubber layer 181 laminated on the upper surface of the second canvas 180B. The first and second canvases 180A and 180B have the same configuration as that of the first modified example, and the reinforcing layer 190 has the same configuration as that of the second modified example.

  Of course, the layer configuration of the molded belt 70 is not limited to the above-described configuration as long as the vulcanized rubber layer 181 and the canvas (shrinked canvas 180) are laminated. However, the canvas (non-shrinkable canvas) is preferably wound so as to be close to or in contact with the inner mold 20 and the outer mold 40 so as to be easily heated by the inner mold 20 or the outer mold 40.

  In the first to third embodiments, the unshrinked canvas 80 may be impregnated with rubber or synthetic resin used for the primer.

  Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples shown below.

[Example 1]
Example 1 is a flat belt (see FIG. 8) shown in a second modified example in which a shrinked canvas, a reinforcing layer, and a vulcanized rubber layer are laminated following the vulcanization molding method of the second embodiment. ) Was manufactured. In Example 1, a primer rubber whose rubber component is natural rubber is applied to one surface of an unshrinked canvas, the unshrinked canvas is wrapped around an inner mold, and a cord is placed on the unshrinked canvas. An unvulcanized rubber sheet was wound. Here, the thickness of the unvulcanized rubber sheet was 10 mm, and natural rubber was used as the rubber component.

  The yarn used for the first yarn is a 140 dtex yarn, the yarn used for the second yarn is a 110 dtex yarn, and the fiber used for the first and second yarns is PET. there were. The canvas used in Example 1 was a canvas having high shrinkage in the width direction and had the width direction shrinkage shown in Table 1.

  As shown in FIG. 5, the laminated body composed of the unshrinked canvas, the core wire, and the unvulcanized rubber sheet is heated for 30 minutes (period m0 + period m1), and the temperature of the inner heat medium and the outer pressure medium. Was increased to 145 ° C. (first temperature t1). Thereafter, the temperature of the inner heat medium and the outer pressure medium was maintained at 145 ° C. (first temperature t1) for 30 minutes (period m2), and the laminate was heated. Next, only the temperature of the inner mold heat medium is increased to 165 ° C. (second temperature t2) that is equal to or higher than a predetermined temperature T (160 ° C.), and the temperature of the inner mold heat medium is 165 ° C. The temperature of the heating medium was maintained at 145 ° C., and the laminate was heated for 5 minutes (period m2 ′). By these heating, the laminate became a belt slab in which a contracted canvas, a reinforcing layer, and a vulcanized rubber layer were integrally laminated as shown in FIG.

  When heating for the period m2 'was completed, the inner mold was taken out from the outer mold, the belt slab was cooled to room temperature (25 ° C) together with the inner mold, and cut into a width of 35 mm to obtain a flat belt of Example 1.

[Comparative Example 1]
Comparative Example 1 was carried out in the same manner as in Example 1 except for the configuration of the unshrinked canvas and the heating temperature and heating time of the heat medium and pressure medium supplied to the inner mold and the outer mold. That is, in Comparative Example 1, the yarn used for the first yarn was a 140 dtex yarn, and the yarn used for the second yarn was a 110 dtex yarn. The canvas used in Comparative Example 1 had low shrinkage in the width direction and had the width direction shrinkage shown in Table 1. The fiber used for the first and second yarns was PET. Natural rubber having the same composition as in Example 1 was used for the unvulcanized rubber sheet, and primer rubber was applied to the unshrinked canvas in the same manner as in Example 1.

  In Comparative Example 1, the temperature of the inner heat medium and the outer pressure medium was raised to 165 ° C., and then maintained at 165 ° C. for 30 minutes, thereby preventing unshrinked canvas, cords, and rubber sheets. The resulting laminate was vulcanized to obtain a belt slab. Thereafter, the belt slab was cooled to room temperature (25 ° C.) and cut into a width of 35 mm to obtain a flat belt.

[Measurement of shrinkage in the width direction of shrinked canvas]
A canvas sample made of the same material as the unshrinked canvas of Example 1 and Comparative Example 1 was prepared. The canvas samples of Example 1 and Comparative Example 1 have a length of 900 mm and a width of 35 mm. In the canvas sample, the first yarn (the yarn in the belt width direction) extends in the longitudinal direction, and the second yarn ( The yarn in the longitudinal direction of the belt) extends in the width direction, that is, the canvas sample of Example 1 was an unshrinkable canvas that can be thermally contracted in the longitudinal direction. The length and width of the canvas sample were measured in a room temperature atmosphere (25 ° C.).

  A plurality of canvas samples of Example 1 were prepared, and each was heated in a heating oven at 120 ° C., 150 ° C., and 160 ° C. for 30 minutes. Each canvas sample heated in each temperature atmosphere was taken out of the heating oven and then the length was measured. And, when the percentage of increase in the length of the canvas sample after heating with respect to the length of the canvas sample before heating (at 25 ° C.) is expressed in%, it is unshrinked when heated from 25 ° C. to each temperature. The contraction rate in the width direction of the canvas. Similarly, for the canvas sample of Comparative Example 1, the shrinkage ratio in the width direction of the unshrinked canvas when heated from 25 ° C. to 160 ° C. was measured.

[Rubber expansion coefficient of vulcanized rubber layer]
A plurality of rectangular belt rubber bodies having a thickness of 10 mm, a width of 35 mm, and a length of 900 mm were sampled from the vulcanized rubber layer of the flat belt of Example 1. In addition, the measured value of the said thickness, width | variety, and length was a thing in 25 degreeC. Each of the belt rubber bodies was heated in a heating oven in an atmosphere of 120 ° C., 150 ° C., and 160 ° C. for 30 minutes. After heating for 30 minutes, the thickness, width, and length of the belt rubber body were measured in a heating oven under the atmosphere of the heating temperature, and the volume of the belt rubber body after heating was calculated. In addition, about each belt rubber body, what integrated the width | variety, length, and thickness was made into the volume of the belt rubber body. The rate of increase in the volume of the belt rubber body after heating with respect to the volume of the belt rubber body before heating expressed in% was defined as the rubber expansion coefficient when heated from 25 ° C. to each temperature. In addition, the rubber expansion coefficient E160 when it heated from 25 degreeC to 160 _degreeC was also measured for the comparative example 1 with the same method.

[Measurement of belt warpage]
The endless flat belts of Example 1 and Comparative Example 1 were attached to two pulleys at an attachment elongation rate of 0.5% so that the canvas side was the inner peripheral side, and the amount of warpage was measured using a laser displacement meter. That is, laser irradiation was carried out on the outer peripheral surface of the belt at the five edges at both edges and the center in the belt width direction, and between the edges and the center, and the positions of these five points were measured. And the difference of the position of each point in the thickness direction of a belt was computed, and the maximum value was made into the amount of curvature of a belt.

  As is apparent from Table 1, the unshrinked canvas of Example 1 does not have a very high shrinkage rate when heated to a low temperature (120 ° C.). On the other hand, when heated to a high temperature (150 ° C. or higher), the shrinkage ratio in the width direction becomes high. In particular, when heated to a predetermined temperature T (160 ° C. or higher), it can be understood that it becomes twice as high as that during low temperature heating. That is, it can be understood that the unshrinked canvas used in this example has a significantly high shrinkage rate at high temperatures. On the other hand, it can be understood that the rubber expansion coefficient according to Example 1 is substantially constant at both low and high temperatures.

In Example 1, 160 ° C. (predetermined temperature T) in the width direction shrinkage W _T of the unshrunk fabric when heated is higher than the rubber expansion ratio of the vulcanized rubber layer E _T when heated to the same temperature The difference from the rubber expansion coefficient E _T was within 3%. In Example 1, in the vulcanization molding process, the unshrinked canvas was heated to a temperature (165 ° C.) higher than the predetermined temperature T (160 ° C.). Therefore, in the vulcanization molding process, the unshrinked canvas is sufficiently shrunk, and the belt warp caused by the shrinkage of the vulcanized rubber layer can be sufficiently reduced. Therefore, the warp amount / belt width is a relatively small value. Became. On the other hand, in Comparative Example 1, since the canvas did not sufficiently shrink in the vulcanization molding process, the belt warpage due to the shrinkage of the vulcanized rubber layer could not be sufficiently reduced, and the warp amount / belt width was The value was relatively large. In the first embodiment, the difference between the width direction shrinkage rate W ₁₂₀ and the rubber shrinkage rate E _{120 and} the difference between the width direction shrinkage rate W ₁₅₀ and the rubber shrinkage rate E ₁₅₀ are also within 2%. It is good also as 120 degreeC or 150 degreeC.

It is sectional drawing for showing the forming belt concerning a 1st embodiment. It is sectional drawing which shows a vulcanization molding apparatus. It is typical sectional drawing of a laminated body. It is a graph which shows typically temperature transition of a heat carrier supplied in an inner model, and change of a vulcanization degree in a 1st embodiment. It is a graph which shows typically temperature transition of a heat carrier supplied in an inner model, and change of a vulcanization degree in a 2nd embodiment. It is a graph which shows typically temperature transition of a heat carrier supplied in an inner model in a 3rd embodiment, and transition of a vulcanization degree. It is sectional drawing for showing the shaping | molding belt which concerns on a 1st modification. It is sectional drawing for showing the shaping | molding belt which concerns on a 2nd modification. It is sectional drawing for showing the shaping | molding belt which concerns on a 3rd modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vulcanization molding apparatus 20 Inner type | mold 27 Outer peripheral surface 30 Laminated body 40 Outer type | mold 70 Flat belt (molding belt)
80 Unshrinked canvas 81 Unvulcanized rubber sheet (unvulcanized rubber layer)
180 Shrinked canvas 181 Vulcanized rubber layer t0 Initial temperature t1 First temperature t2 Second temperature

Claims (6)

A laminate in which a non-shrinkable canvas formed of synthetic resin fibers and heat-shrinkable in the belt width direction and an unvulcanized rubber layer formed of unvulcanized rubber are laminated, is heated,
As a result, the unshrinked canvas is thermally shrunk in the belt width direction to become a shrunken canvas, the unvulcanized rubber layer becomes a vulcanized rubber layer, and the shrunken canvas and the vulcanized rubber layer are integrated. A molded belt obtained by molding into
When the laminate is heated, at least the unshrinked canvas is heated to a predetermined temperature or higher,
The difference between the width direction shrinkage rate in the belt width direction of the unshrinked canvas when heated to the predetermined temperature and the rubber expansion rate of the vulcanized rubber layer is within 2%, or the width direction shrinkage rate is A molded belt characterized by being higher than the rubber expansion coefficient.   The molding belt according to claim 1, wherein the width direction shrinkage rate is higher than the rubber expansion rate.   2. The molded belt according to claim 1, wherein the uncontracted canvas has a longitudinal contraction rate in the longitudinal direction of the belt when heated to the predetermined temperature, which is lower than the contraction rate in the width direction. A laminated body in which a non-shrinkable canvas made of synthetic resin fiber and heat-shrinkable in the belt width direction and an unvulcanized rubber layer formed of unvulcanized rubber are heated, and thereby the unvulcanized rubber is heated. The vulcanized rubber layer is vulcanized and expanded into a vulcanized rubber layer, and the unshrinked canvas is contracted in the belt width direction to form a contracted canvas, and the vulcanized rubber layer and the contracted canvas are integrally molded. A vulcanization molding process to obtain a belt slab;
The belt slab is cooled and cut into a predetermined width, whereby the expanded vulcanized rubber layer is contracted in the width direction of the belt, and a cooling step for obtaining a molded belt is provided.
In the vulcanization molding step, at least the unshrinked canvas is heated to a predetermined temperature or higher,
Due to the shrinkage of the unshrinked canvas in the belt width direction, the warpage in the width direction of the molded belt due to the shrinkage of the vulcanized rubber layer is reduced,
The difference between the width direction shrinkage rate in the belt width direction of the unshrinked canvas when heated to the predetermined temperature and the rubber expansion rate of the vulcanized rubber layer is within 2%, or the width direction shrinkage rate is A method for producing a belt, characterized by being higher than the rubber expansion coefficient.   At least the non-shrinkable canvas and the unvulcanized rubber layer are wound in this order on the outer peripheral surface of the columnar inner mold so that the cylindrical laminated body is mounted on the inner mold and surrounds the inner mold on which the stacked body is mounted. The belt manufacturing method according to claim 4, wherein an outer mold is arranged on the belt, and the laminate is clamped by the inner mold and the outer mold in the vulcanization molding step. The vulcanization molding step includes a first heating step of heating the laminated body at a first temperature from the non-shrinkable canvas side and the rubber layer side;
Including a second heating step of heating the laminate from the non-shrinkable canvas side at a second temperature different from the first temperature;
The belt manufacturing method according to claim 4, wherein the second temperature is higher than the predetermined temperature.

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