JP2016038010A - Endless belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endless belt that is imparted with an antistatic performance without deterioration in such performance as flexibility that is normally required to an endless belt.SOLUTION: An endless belt 10 includes a structure where an elastic layer 11 containing an elastic material and an endless textile 12 impregnated with conductive rubber cement 13 are laminated. Preferably, the rubber cement 13 contains a rubber constituent, a conductive imparting agent and a solvent, for example, the conductive imparting agent is carbon black. Further preferable, the rubber cement contains at least 22 pts.mass of the conductive imparting agent based on 100 pts.mass of the rubber constituent.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an endless belt provided with antistatic performance.

  Endless belts are used in applications such as power transmission belts in automobiles, industrial machines, etc., and conveyor belts for transporting banknotes, tickets, cards, etc. in financial terminal devices, automatic ticket gates, ticket vending machines, and the like. Such an endless belt is composed of a reinforcing material such as a fiber material (for example, knitted fabric) and an elastic material such as rubber.

  Fibers and rubbers generally have insulating properties, and endless belts composed of these fibers, for example, may be rubbed due to contact between belts, or may be rubbed due to contact between belts and other members. May be charged by friction (static electricity). Since there are problems such as the occurrence of spark discharge (spark) due to this static electricity, attempts have been made to impart antistatic performance to the endless belt.

  For example, Patent Document 1 describes that a conductive yarn is used as a raw yarn of a knitted fabric as a material to impart antistatic performance to an endless belt. However, the conductive yarn is expensive and causes an increase in product cost. If the amount of conductive yarn used is reduced in order to reduce costs, the endless belt cannot be provided with sufficient antistatic performance. Patent Document 2 describes that carbon black or the like is added to an elastic material as a raw material to impart antistatic performance to the endless belt. However, the addition of carbon black to the elastic material adversely affects performances other than the antistatic performance, such as the endless belt to be obtained loses flexibility and is difficult to stretch.

JP 2002-255324 A JP 2002-322358 A

  An object of the present invention is to provide an endless belt imparted with antistatic performance without impairing performance such as flexibility normally required for the endless belt.

As a result of intensive studies to solve the above problems, the present inventors have found a solution means having the following configuration, and have completed the present invention.
(1) An endless belt having a structure in which an elastic layer containing an elastic material and an endless knitted fabric impregnated with conductive rubber paste are laminated.
(2) The endless belt according to (1), wherein the rubber paste contains a rubber component, a conductivity imparting agent, and a solvent.
(3) The endless belt according to (2), wherein the conductivity imparting agent is contained in a proportion of at least 22 parts by mass with respect to 100 parts by weight of the rubber component.
(4) The endless belt according to (2) or (3), wherein the conductivity-imparting agent is carbon black.
(5) The endless belt according to any one of (1) to (4), wherein the endless knitted fabric forms a surface layer of the endless belt.
(6) The endless belt according to (1) to (5), wherein the volume resistivity is 4.6 × 10 ⁴ Ω · cm or less.

  The endless belt of the present invention is imparted with antistatic performance without impairing normally required performance such as flexibility. Furthermore, the endless belt of the present invention does not contain expensive conductive yarns and the like, and the cost can be reduced.

It is explanatory drawing which shows one embodiment of the endless belt of this invention. It is explanatory drawing which shows the other embodiment of the endless belt of this invention. It is a schematic diagram for demonstrating the method to measure the driving voltage of an endless belt. It is a schematic diagram for demonstrating the method to measure the volume specific resistivity of an endless belt.

  Hereinafter, the endless belt of the present invention will be described with reference to FIG. FIG. 1 is an explanatory view showing an embodiment of an endless belt of the present invention. An endless belt 10 shown in FIG. 1 has a structure in which an elastic layer 11 containing an elastic material and an endless knitted fabric 12 impregnated with conductive rubber paste 13 are laminated.

(Elastic layer)
The elastic layer 11 is made of an elastic material. The elastic material is not particularly limited. For example, nitrile rubber, chloroprene rubber, chlorosulfonated polyethylene, polybutadiene rubber, natural rubber, ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), hydrogenated nitrile rubber (H- NBR), millable urethane, acrylic rubber, silicon rubber, fluorine rubber, thermosetting polyurethane, thermoplastic polyurethane, thermoplastic polyester, carboxylated nitrile rubber, and the like. Only one type of elastic material may be used, or a mixture of two or more types may be used.

  Various additives such as processing aids, plasticizers, colorants, ultraviolet absorbers, and anti-aging agents may be added to the elastic material as long as the effects of the present invention are not impaired.

  The thickness of the elastic layer 11 is appropriately set depending on the use of the endless belt 10 and is, for example, about 0.5 to 1.0 mm, but is not particularly limited.

(Endless knitted fabric)
The endless knitted fabric 12 is not particularly limited as long as the endless knitted fabric 12 is obtained by knitting a fiber, either by warp knitting or weft knitting. Examples of the fibers forming the endless knitted fabric 12 include polyester fibers, nylon fibers, aramid fibers, glass fibers, and cotton yarns. The endless knitted fabric 12 may be obtained using only one type of fiber, or may be obtained using two or more types of fibers. The thickness of the fiber which forms the endless knitted fabric 12 is not specifically limited, For example, it is about 70-280T (decitex).

  The endless knitted fabric 12 is impregnated with a conductive rubber paste 13. The rubber paste 13 contains, for example, a rubber component, a conductivity imparting agent, and a solvent. As a rubber component, the above-mentioned elastic material is mentioned, for example. The rubber component and the elastic material forming the elastic layer 11 may be the same or different.

  Examples of the conductivity-imparting agent include carbon-based conductivity imparting agents such as carbon black, graphite, and carbon fiber; and metal-based conductivity imparting agents such as various metal fine powders (copper, iron, aluminum, etc.). It is done.

  The solvent is not particularly limited as long as it can dissolve the rubber component (elastic material), and examples thereof include methyl ethyl ketone (MEK) and toluene.

  Furthermore, you may add another additive to the rubber paste 13 as needed. Examples of such additives include vulcanizing agents, vulcanization accelerators, co-crosslinking agents, and adhesives.

The rubber paste 13 preferably contains at least 22 parts by weight of a conductivity imparting agent and 5 to 10 parts by weight of a processing aid such as a vulcanizing agent with respect to 100 parts by weight of the elastic material. Normally, the rubber paste 13 is adjusted with the above-mentioned solvent so that the solid content concentration is about 10% by weight. The rubber paste 13 is not limited to a paste-like material, and may be a low-viscosity liquid material as long as it can be applied to the endless knitted fabric 12. Rubber cement 13 is preferably 2.5 mg / cm ² in terms of solid content, more preferably at a rate of 2.5~4.0mg / cm ^2, is applied to the endless knitted fabric 12. When the rubber paste 13 is applied at such a ratio, the endless belt 10 can be provided with better antistatic performance.

In particular, carbon black is preferable as the conductivity imparting agent. When the coating amount of carbon black is, for example, 0.55 mg / cm ² or more, excellent antistatic performance can be imparted to the endless belt 10.

(Endless belt)
As shown in FIG. 1, the endless belt 10 of the present invention has a laminated structure of an elastic layer 11 containing an elastic material and an endless knitted fabric 12 impregnated with conductive rubber paste 13. The endless belt 10 according to the present invention can be produced by any method as long as the elastic layer 11 and the endless knitted fabric 12 are fixed and do not peel off.

  First, a cylindrical mold corresponding to the desired size of the endless belt 10 is prepared. An endless knitted fabric 12 is placed on the outer surface of the cylindrical mold. The endless knitted fabric 12 has a size (peripheral length) that cannot be removed by covering the mold. The endless knitted fabric 12 is impregnated with a conductive rubber paste 13 in advance. Examples of the impregnation method include a method of impregnating the endless knitted fabric 12 with the rubber paste 13 using a coating means such as a coater or a brush, or a method of impregnating the rubber paste 13 with the endless knitted fabric 12 by dipping. It is done.

  Next, an elastic layer 11 that matches the size of the endless knitted fabric 12 is prepared, and the elastic layer 11 is placed on the outer surface of the cylindrical mold so as to overlap the endless knitted fabric 12. As the elastic layer 11, for example, an endless sheet made of the above-described elastic material is used. Thereafter, the elastic layer 11 (endless sheet) and the endless knitted fabric 12 are fixed under heat and pressure conditions, and the endless belt 10 is obtained. For example, when the rubber paste 13 contains a vulcanizing agent, the elastic layer 11 and the endless knitted fabric 12 are fixed by vulcanization molding (vulcanization adhesion).

  The endless belt 10 thus obtained has a desired size according to the application. For example, the width is about 8 to 200 mm, the circumference is about 80 to 1500 mm, and the thickness is 0.6 to 2. About 0.0 mm. In the endless belt 10 thus obtained, any surface of the elastic layer 11 and the endless knitted fabric 12 may be used as a surface of the belt (for example, a transport surface when used as a transport belt).

  For example, when used as a transport belt for paper sheets such as banknotes and tickets, the paper sheets may be sandwiched and transported by the transport surfaces of the two transport belts. In such a case, the surfaces of the two belts rub against each other and become easy to be charged. Therefore, it is preferable that the endless knitted fabric 12 side on which antistatic processing is applied forms the surface layer of the endless belt 10.

  As described above, the endless belt having the two-layer structure of the elastic layer 11 and the endless knitted fabric 12 has been described based on FIG. 1, but the endless belt of the present invention is not limited to the endless belt having the two-layer structure. For example, as long as the elastic layer 11 and the endless knitted fabric 12 are provided, an endless belt having a three-layer structure as shown in FIG. 2 may be used.

  The endless belt 20 shown in FIG. 2 is formed with elastic layers 21a and 21b so as to sandwich an endless knitted fabric 22 impregnated with conductive rubber paste 23. The elastic layer, the endless knitted fabric, and the rubber paste are as described above, and a description thereof is omitted.

The endless belt of the present invention preferably has a volume resistivity of 4.6 × 10 ⁴ Ω · cm or less. When the volume resistivity is 4.6 × 10 ⁴ Ω · cm or less, it has appropriate conductivity and is difficult to be charged (that is, it can be said that sufficient antistatic performance is imparted). Furthermore, performance such as flexibility normally required for an endless belt is not impaired. Therefore, the endless belt of the present invention is less likely to cause spark discharge due to static electricity, and is used for transmission belts in automobiles, industrial machines, etc., banknotes, tickets, cards, etc. in financial terminal devices, automatic ticket gates, ticket vending machines, etc. It is suitably used as a transport belt for transporting the belt.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to these Examples.

Example 1
First, a rubber paste to be applied to the knitted fabric was prepared. 45.0 parts by weight of carbon black (particle size 40 nm) and 7.5 parts by weight of a vulcanizing agent (peroxide vulcanizing agent) were added and mixed with 100 parts by weight of millable urethane. To the obtained mixture, methyl ethyl ketone was added and stirred so that the solid content concentration was about 10% by weight to prepare a rubber paste.

The obtained rubber paste was applied to an endless knitted fabric made of polyester (application amount 2.5 mg / cm ² ). An endless knitted fabric impregnated with rubber paste was placed on the outer surface of a cylindrical mold (outer diameter 232 mm), and a urethane rubber sheet (width 500 mm, thickness 0.8 mm) was placed thereon. Then, vulcanization molding was performed under heating and pressing conditions to obtain an endless belt 30 (width 10 mm, circumferential length 230 mm, thickness 0.65 mm).

The obtained endless belt 30 was measured for (1) traveling voltage and (2) volume resistivity. The measurement was performed according to the following procedure.
(1) Traveling Band Voltage As shown in FIG. 3, the obtained endless belt 30 was attached to two shafts 34 so as to extend 5% between the two shafts. The pulley diameter of the shaft 34 is 20 mm. The belt 30 was run at a speed of 1.7 m / sec for 24 hours (temperature 23 ° C., humidity 50%). After the running, the electrostatic potential was measured with a Statilon measuring device 35 (STATIRON-M2 manufactured by Sicid Static Co., Ltd.) (measurement distance 50 mm). From the measurement results, the charged voltage was 100 V or less, which was lower than the general standard (100 V), and it was found that the endless belt 30 was not charged during traveling.

(2) Volume resistivity As shown in FIG. 4, the obtained endless belt 30 was cut into a strip shape to obtain a test piece 30a (width (L1) 10 mm, length (L2) 80 mm, thickness (L3 ) 0.65 mm). Next, the conductive paste 36 was applied to both ends of the obtained test piece 30a. As the conductive paste 36, Dotite D-550 manufactured by Fujikura Kasei Co., Ltd. was used, and applied with a width (L4) of 5 mm from each end. An electrode was provided on the applied conductive paste 36, an insulation resistance meter 37 (2426 digital insulation resistance meter manufactured by Yokogawa Electric Corporation) was connected between both ends of the test piece 30a, and the resistance value was measured. The measurement was performed under conditions of a temperature of 23 ° C. and a humidity of 50%. From the obtained resistance value and the size of the test piece 30a, the volume resistivity (Ω · cm) was calculated using the following formula. The volume resistivity of the endless belt 30 was 1.9E + 04 Ω · cm (19000 Ω · cm).

Volume resistivity (Ω · cm) = (V × w × t) / (I × L)
here,
V: Average of potential difference (Ω · cm)
w: width of the test piece 30a (cm)
t: thickness of the test piece 30a (cm)
I: Energized current (A)
L: Distance between potential difference electrodes (cm)

(Comparative Example 1)
A rubber paste was prepared in the same procedure as in Example 1 except that carbon black was not used. Next, an endless belt was obtained in the same procedure as in Example 1 except that this rubber paste was impregnated into an endless knitted fabric having conductivity (width 10 mm, circumference 230 mm, thickness 0.65 mm). With respect to the obtained endless belt, the volume resistivity was measured by the same procedure as in Example 1. As a result, it was 4.6E + 04 Ω · cm (46000 Ω · cm).

  The endless belt 30 obtained in Example 1 has a lower volume resistivity than the endless belt obtained in Comparative Example 1, that is, better conductivity than the endless belt obtained in Comparative Example 1. It can be seen that Therefore, it can be seen that the endless belt 30 is not charged during traveling and has antistatic performance.

10, 20 Endless belt 11, 21a, 21b Elastic layer 12, 22 Endless knitted fabric 13, 23 Rubber glue

Claims (6)

  An endless belt having a structure in which an elastic layer containing an elastic material and an endless knitted fabric impregnated with conductive rubber paste are laminated.   The endless belt according to claim 1, wherein the rubber paste contains a rubber component, a conductivity imparting agent, and a solvent.   The endless belt according to claim 2, wherein the conductivity-imparting agent is contained in a proportion of at least 22 parts by mass with respect to 100 parts by weight of the rubber component.   The endless belt according to claim 2 or 3, wherein the conductivity imparting agent is carbon black.   The endless belt according to any one of claims 1 to 4, wherein the endless knitted fabric forms a surface layer of the endless belt. The endless belt according to any one of claims 1 to 5, wherein the volume resistivity is 4.6 x 10 ⁴ Ω · cm or less.

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