JP7473932B2 - Load-bearing belt - Google Patents

Description

The present invention relates to a load-bearing belt.

Belts made of narrow woven fabrics are used as load-bearing belts in a wide range of fields, such as seat belts in cars and playground equipment, hand and shoulder belts for backpacks and bags, lifting belts, sling belts, container belts, crane belts, etc. used for transport work in construction, civil engineering, landscaping, shipbuilding, cargo handling, agriculture and forestry, etc., harness belts for working at height, etc.

For example, Patent Document 1 discloses a technology that uses fibers with a specific strength and specific thermal stress as the weft yarn, making it easy to process the weft into the desired width.

Japanese Patent Application Laid-Open No. 5-302233

Belts that are subjected to the above loads must be able to withstand lifting and transporting heavy objects even when used repeatedly, and maintaining performance is important for belts in harnesses used for work at heights, etc., because high safety is required by preventing falls. Although the initial strength of such belts is determined by standards, the belts will deteriorate and will be unable to maintain their initial performance if used repeatedly or under conditions of a load greater than expected.

The objective of the present invention is to solve the above problems and to provide a belt that maintains its initial strength for a long period of time and is resistant to deterioration.

In order to solve the above-mentioned problems, the inventors of the present invention have studied the deterioration state of the belt. When a belt is used under load, the load is almost never applied uniformly to each part in the longitudinal direction of the belt. In other words, the load applied to each part of the belt changes depending on the shape of the transported object and the hanging position when hanging, so the load is not applied uniformly to all parts of the belt. If the belt is used repeatedly under such conditions, the load is not applied uniformly, so the shape of the belt is distorted, and the distortion creates areas where stress is further concentrated, causing the belt to deteriorate in certain areas and making it impossible to maintain its initial strength. In addition, due to the influence of the uneven load, not only does the belt become distorted and curved, but fuzz and loop fuzz are generated on the surface of the belt, making it impossible to maintain its initial strength. In addition, when the belt is placed over an object to be lifted or transported, a difference in the bending angle occurs between the inside of the belt that is in contact with the object and the outside surface that is not in contact with the object. As a load is applied in this state of bending difference, some of the warp threads become loose, forming small loop fuzz. These loop fuzz can grow into large surface fuzz with repeated use, leading to a decrease in the quality and strength of the belt.

The inventors of the present invention studied the deterioration of the belt caused by use, and then investigated a form of the belt that is less likely to cause distortion and less likely to generate loop fuzz on the belt surface. As a result, they arrived at the present invention.

That is, the present invention is a load-bearing belt made of a warp and weft double weave,
The weave is a double plain weave.
The weave density is such that the warp density is higher than the weft density,
The warp yarns that make up the front and back weave are made of multifilament yarns on both sides.
The weft yarns constituting the front and back structures are composed only of heat-fusible yarns having a heat-fusible component on both the front and back sides,
The thermal fusion yarn is in the form of a multifilament yarn, and all of the fibers constituting the multifilament yarn have a thermal fusion component,
The fiber having a heat-fusible component is a core-sheath type composite fiber having a core composed of a high melting point component and a sheath composed of a low melting point component,
The heat-sealing component that constitutes the weft yarn is melted and solidified , so that all the warp yarns are bonded and fixed, and restrained .
In plain weave, floating warp threads come into contact with each other,
The gist of the load-bearing belt is that the floating weft yarns above the submerged warp yarns present between the floating warp yarns are covered by the above-mentioned contacting warp yarns, and the weft yarns constituting the woven fabric are not exposed on the surface of the woven fabric and are not visible to the naked eye.

The present invention will be described in detail below.

The load-bearing belt of the present invention is a narrow woven fabric, constructed with a warp and weft double weave, and the weave structure is a double plain weave. The warp and weft double weave results in a thick fabric with a strong texture, and the double plain weave structure, in which the warp threads and weft threads are alternately combined, results in a strong and sturdy structure on both the front and back.

The weaving density of the double weave is such that the warp density is higher than the weft density. Preferably, it is 10 times higher. In the load-bearing belt, the warp direction of the woven fabric constituting the belt is the longitudinal direction of the belt, and the load is applied in the longitudinal direction of the belt, so that the load is applied in the warp direction. In order to more effectively exert the strength of the warp, the warp is arranged in a straight line without bending the warp in the woven fabric, that is, by reducing the number of crossing points where the warp and weft cross, the number of bending points is reduced. In order to reduce the number of bending points of the warp, in the present invention, the warp density is high and the weft density is reduced, so that the warp arranged densely exerts sufficient strength, and further, by reducing the weft density, the number of crossing points between the warp and weft is reduced, and the warp is arranged linearly, so that the strength of the belt in the longitudinal direction is effectively improved structurally. Since the warp is arranged more linearly as the weft density is lower, it is preferable that the warp density is 10 times higher than the weft density. As will be described later, the weft threads serve to bond and fix the warp threads by fusion and solidification, and the interval at which the weft threads are arranged is the interval at which the warp threads are fixed. Therefore, the weft thread density is preferably 10 to 25 threads/2.54 cm. If the weft thread density is too high, the number of bending points of the warp threads increases, and the degree of freedom of the warp threads is extremely lost, making the warp threads too hard to bend and making it difficult to properly align the belt with the object. On the other hand, if the weft thread density is too low, it is difficult to effectively perform the role of bonding and fixing the warp threads. In the load-bearing belt of the present invention, the warp threads are restrained by the interval at which the weft threads are arranged (weft thread density), so that when the load-bearing belt is used, the warp threads are less likely to shift, the belt itself is less likely to be distorted, and the strength is less likely to decrease and fluff is less likely to occur due to repeated use.

In a plain weave, the floating warp threads on both surfaces are in contact with each other, and the floating weft threads above the submerged warp threads between the floating warp threads are not exposed to the surface of the fabric, so that the warp threads can be well maintained in a state where they are bonded and fixed by the fusion and solidification of the weft threads. Depending on the total fineness of the multifilament warp threads, the warp thread density is preferably 100 threads/2.54 cm or more, more preferably 200 threads/2.54 cm or more. In addition, the warp thread density as a fineness is at least 100,000 decitex/2.54 cm or more, preferably 300,000 decitex/2.54 cm or more. In addition, by setting the warp thread density in the above range, good belt strength is exhibited. Depending on the total fineness of the multifilament warp threads, the upper limit of the warp thread density is about 300 threads/2.54 cm, and the fineness is 400,000 decitex/2.54 cm.

The upper limit of the ratio of warp density to weft density (warp density/weft density) should be set taking into consideration the spacing at which the weft threads secure the warp threads, as described above, and the warp density and total warp fineness to be arranged to improve the belt strength, but should be around 30 times.

The warp threads constituting the front and back structures of the double weave are made of multifilament yarns on both sides. Since multifilament yarns are made up of multiple fibers, they are more flexible and easier to deform than monofilament yarns, and can be arranged at a high weave density. Furthermore, as mentioned above, the warp threads floating in the weave structure come into contact with each other on the floating weft threads above the submerged warp threads that exist between the floating warp threads, covering the floating weft threads and preventing them from being well exposed on the surface of the fabric, which effectively improves the belt strength and makes it less susceptible to deterioration due to repeated use.

The multifilament yarn can be preferably untwisted or loosely twisted. Since there is no constraint due to twist between the fibers that make up the multifilament yarn, the multifilament yarn (warp yarn) effectively covers the floating weft yarn, and it is possible to satisfactorily create a state in which it is not exposed on the surface of the woven fabric. Also, in order to prevent the weft yarn from being exposed on the belt surface, in the double weave structure, the knots are warp knots, and by using warp knots, it is less likely that the strength will decrease or deteriorate due to repeated use.

The multifilament yarns constituting the warp preferably have a total fineness of 1000 decitex or more and a constituent fiber count of 100 or more, and more preferably a total fineness of 1100 decitex or more. The upper limit of the total fineness is about 3000 decitex, and the upper limit of the constituent fiber count is about 250.

The material of the warp multifilament yarn may be selected appropriately depending on the application, but it is preferable for it to be made of a polyester polymer, and in particular, polyethylene terephthalate, because it has excellent mechanical strength, little moisture absorption, and is less susceptible to dimensional changes.

The weft yarns constituting the front and back structures of the double weave are both composed of heat-sealed yarns having a heat-sealed component. The heat-sealed yarns have a heat-sealed component, which melts and solidifies to function as an adhesive, and the melted and solidified heat-sealed component bonds the warp yarns. The heat-sealed yarns are multifilament yarns in terms of handling and strength. In the case of multifilament yarns, all of the fibers constituting the multifilament yarns are fibers having a heat-sealed component. In addition, the fibers having a heat-sealed component are composite fibers composed of a heat-sealed component and a high-melting component, and are core-sheath type composite fibers in which the heat-sealed component constitutes the sheath and the high-melting component constitutes the core. The fineness of the weft yarns (total fineness in the case of multifilament yarns) is preferably about the same as that of the warp yarns, and is preferably 1000 decitex or more. The upper limit is about the same as that of the warp yarns, 3000 decitex.

The melting point of the heat-sealing component is preferably 40°C or more lower than the melting point of the multifilament yarn constituting the warp, and more preferably 50°C or more lower. By making the melting point difference 40°C or more, during the heat treatment for melting and solidifying by heat fusion, only the heat-sealing component is melted well, and the warp yarn is not affected by heat, maintaining the fiber strength and maintaining the quality of the resulting belt. In addition, when the fiber constituting the weft is a composite fiber having a heat-sealing component, or when a heat-sealing fiber is used in combination with other fibers, the melting points of the high-melting component of the composite fiber and the polymers constituting the other fibers are preferably 40°C or more higher than the melting point of the heat-sealing component, and more preferably 50°C or more. In addition, when the heat-sealing component does not have a clear melting point, the softening temperature is considered to be the melting point.

The heat-sealing component plays a role in firmly fixing the warp threads, so it is preferable that the polymer constituting the heat-sealing component and the warp threads are compatible. Therefore, it is preferable that they are composed of the same type of resin, and in particular, it is preferable that both are composed of polyester-based resins.

The load-bearing belt of the present invention can be obtained, for example, by the following method. That is, the above-mentioned warp and weft threads are prepared, and woven in a double plain weave structure with the above-mentioned warp and weft densities. The obtained green fabric is then subjected to a heat-setting process to obtain the belt of the present invention. In the heat-setting process, the heat-sealing component constituting the weft thread is melted to function as a thermal adhesive, and the warp threads are fixed in the longitudinal direction at equal intervals according to the weft density by the thermal adhesive (heat-sealing component) that is melted and solidified. The processing temperature and processing speed in the heat-setting are the temperature and processing speed at which the heat-sealing component constituting the weft thread melts and functions as a thermal adhesive. The heat-setting process may be performed using a dry heat oven. In addition, by performing a heat treatment while stretching during the heat-setting process, the heat-sealing component of the weft thread is melted and solidified, and each of the arranged warp threads is linearly aligned in the longitudinal direction of the belt, thereby improving the quality of the product and maximizing the strength of the warp thread, thereby improving the strength of the belt. The stretching ratio is preferably about 0.5 to 1.5%.

In the present invention, the width of the belt is preferably, for example, about 10 mm to 300 mm, but is not limited to this range and may be freely set as appropriate depending on the application. The length of the belt may be freely set as appropriate depending on the application, and may be less than 1 m, or may be several meters to several tens of meters.

According to the present invention, since the belt of the present invention has the above-mentioned configuration, it is possible to provide a load-bearing belt that maintains its initial strength for a long period of time even with repeated use, is resistant to distortion, and has excellent dimensional stability and durability.

FIG. 2 is a schematic plan view of a sample in a state where distortion occurs and deformation occurs due to wear evaluation in the wear evaluation of the present invention. 1 is a plan view photograph showing the state of a sample before abrasion evaluation in Example 1. 1 is a plan view photograph showing the state of a sample after 500 abrasion cycles in the abrasion evaluation of Example 1. 1 is a plan photograph showing the state of a sample after 2000 abrasion cycles in the abrasion evaluation of Example 1. 1 is a plan view photograph showing the state of a sample of Comparative Example 1 before abrasion evaluation. 1 is a plan view photograph showing the state of a sample after 500 abrasion cycles in the abrasion evaluation of Comparative Example 1. 1 is a plan photograph showing the state of a sample after 2000 abrasion cycles in the abrasion evaluation of Comparative Example 1. 1 is a side photograph showing the state of a sample before abrasion evaluation in Example 1. 1 is a side photograph showing the state of a sample after 500 abrasion cycles in the abrasion evaluation of Example 1. 1 is a side photograph showing the state of a sample after 2000 abrasion cycles in the abrasion evaluation of Example 1. 1 is a side photograph showing the state of a sample of Comparative Example 1 before wear evaluation. 1 is a side photograph showing the state of a sample after 500 abrasion cycles in the abrasion evaluation of Comparative Example 1. 1 is a side photograph showing the state of a sample after 2000 abrasion cycles in the abrasion evaluation of Comparative Example 1.

Next, the present invention will be described based on examples, but the present invention is not limited to these examples.

Example 1
As the warp yarn, a multifilament yarn made of polyethylene terephthalate fiber having a size of 1670 decitex and 192 filaments (product number 1670T192-S723, manufactured by Unitika Ltd.) was prepared. This multifilament yarn was substantially untwisted.
In addition, as the weft yarn, a fusion yarn 1100 decitex/192 filaments (manufactured by Unitika Ltd., product number 1100T192-CM27) made of a multifilament yarn composed of a core-sheath type composite fiber (the sheath, which is the fusion component, is a copolymer polyester having a melting point of 160°C, and the core is polyethylene terephthalate) was prepared.

A narrow fabric with a width of 40 mm was woven with a warp density of 208 threads/2.54 cm, a weft density of 18 threads/2.54 cm, a double flat weave, and warp knots.

The resulting narrow woven fabric (grey) was subjected to heat treatment by passing it through a dry heat oven set at 185°C at a speed of 2.9 m/min and a stretch ratio of 1%, to obtain the belt of Example 1.

Comparative Example 1
A belt of Comparative Example 1 was obtained in the same manner as in Example 1, except that a multifilament yarn of 1100 decitex/192 filaments made of polyethylene terephthalate (product number 1100T192-E223, manufactured by Unitika Ltd.) was used as the weft yarn.

The obtained belts of Example 1 and Comparative Example 1 were subjected to the abrasion test described below to evaluate the occurrence of distortion due to abrasion and the surface condition. In addition, a tensile strength test was performed to evaluate the decrease in strength due to abrasion.
(Wear test)
Samples of 1025 mm in length were taken from the belts of Example 1 and Comparative Example 1 (n=3). The samples were placed in an abrasion tester with a gripping distance of 915 mm. A stainless steel hexagonal bar with a cross section of a regular hexagon with a side length of 7 mm was used as the abrasion body, and the sample was brought into contact with the abrasion body at an angle of 90°, and was subjected to reciprocal abrasion with a stroke width of 300 mm, a load of 2 kg, and a speed of 30 reciprocations/min. Before abrasion, after 500 abrasion reciprocations, and after 2000 abrasion reciprocations, the flat surface condition and side surface were confirmed, and the occurrence of distortion and the surface condition were evaluated.

(Evaluation of Distortion Occurrence)
FIG. 1 is a schematic plan view of a sample in a state in which distortion occurs and deformation occurs due to wear. The worn sample is placed on a flat surface, and the central part of the sample is curved in a mountain shape due to wear. In addition, in the state before wear, there is no distortion, and the angle formed by the straight line (reference line) connecting the lower ends of both ends of the sample and the circumstantial line on the lower side of the sample at the lower end is 0°. The worn sample was placed on a flat surface, and the angle formed by the straight line (reference line) connecting the lower ends of both ends of the sample and the circumstantial line on the lower side at the lower end was measured at the lower end to evaluate the state of distortion. Note that, although only one of the angles of the lower end is shown in FIG. 1, both ends were measured, and the average value was calculated from the measured values for 500 abrasion cycles and 2000 abrasion cycles, and was used as the distortion angle.

(Evaluation of surface condition)
The lateral surfaces of the worn samples were photographed to evaluate the surface condition.

(Tensile strength)
Based on JIS L 1096 Tensile Strength (Strip Method), a precision universal testing machine "Instron 5982" was used as a tensile tester, and measurements were performed at a tensile speed of 200 mm/min to determine the strength at the time of breakage. When placing the sample on the tester for the measurement, the sample was placed so that the abrasion site due to the abrasion test was located at the center.

The results of the strain evaluation showed that in Example 1, the strain angle before the test was 0°, after 500 abrasion cycles it was 5.2°, and after 2000 abrasion cycles it was 9.7°, while in Comparative Example 1, the strain angle before the test was 0°, after 500 abrasion cycles it was 14.2°, and after 2000 abrasion cycles it was 23.7°. It can be seen that the belt of the present invention is less susceptible to strain, has small shape changes, and has excellent dimensional stability. Also, Figures 2 to 7 show examples of samples of Example 1 and Comparative Example 1 before abrasion and after each number of abrasion cycles, placed on a flat surface (photographs). In the photographs, masking tape is applied as a straight line connecting the lower ends of both ends of the sample as a reference line.

Figures 8 to 13 show side photographs of examples of samples of Example 1 and Comparative Example 1 before and after each number of abrasions, showing the surface condition. As shown in these side photographs, the warp threads of Comparative Example 1 were significantly lifted and loop fuzz was generated after 500 abrasion cycles, and were significantly lifted and numerous loop fuzz was generated on the belt surface after 2000 cycles, whereas the warp threads of Example 1 of the present invention were slightly lifted but did not show any major change after 500 abrasion cycles, and were lifted and had a small amount of loop fuzz generated after 2000 cycles. The belt of the present invention was less likely to fuzz even with repeated abrasion, and maintained a high quality.

The evaluation results of the tensile strength of Example 1 were 30.8 kN before the abrasion test, 30.0 kN after 500 abrasion cycles, and 30.9 kN after 2000 abrasion cycles, while Comparative Example 1 was 32.7 kN before the abrasion test, 24.8 kN after 500 abrasion cycles, and 22.4 kN after 2000 abrasion cycles. In the examples, the tensile strength value after 2000 abrasion cycles is slightly larger than that before the abrasion test, which is considered to be within the margin of error. In terms of tensile strength, the belt of the present invention had no change in strength and excellent strength retention. On the other hand, Comparative Example 1 maintained about 76% of the initial strength (before abrasion) after 500 abrasion cycles, and maintained about 69% of the initial strength after 2000 abrasion cycles, and the strength loss due to abrasion was significantly larger than that of the belt of the present invention.

Claims (5)

A load-bearing belt made of warp and weft double weave,
The weave is a double plain weave.
The weave density is such that the warp density is higher than the weft density,
The warp yarns that make up the front and back weave are made of multifilament yarns on both sides.
The weft yarns constituting the front and back structures are composed only of heat-fusible yarns having heat-fusible components on both the front and back sides,
The thermal fusion yarn is in the form of a multifilament yarn, and all of the fibers constituting the multifilament yarn have a thermal fusion component,
The fiber having a heat-fusible component is a core-sheath type composite fiber having a core composed of a high melting point component and a sheath composed of a low melting point component,
The heat-sealing component that constitutes the weft yarn is melted and solidified , so that all the warp yarns are bonded and fixed, and restrained .
In plain weave, floating warp threads come into contact with each other,
The load-bearing belt is characterized in that the floating weft yarns on the submerged warp yarns present between the floating warp yarns are covered by the above-mentioned contacting warp yarns, and the weft yarns constituting the woven fabric are not exposed on the surface of the woven fabric and are not visible to the naked eye. The load-bearing belt according to claim 1, characterized in that the knots in the warp and weft double weave are warp knots. The load-bearing belt according to claim 1 or 2, characterized in that the warp density is at least 10 times higher than the weft density. A load-bearing belt according to any one of claims 1 to 3, characterized in that the weft density is 10 to 25 threads/2.54 cm. 5. The load-bearing belt according to claim 1, wherein the warp threads of the multifilament yarns have a fineness of 1000 decitex or more and a number of filaments constituting the warp threads is 100 or more.