JP2996684B2 - Antistatic rubber belt and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is used as a belt for power transmission and transportation, and its belt structure is made of a rubber elastic body without a core or a cover cloth and containing no conductive carbon black. And a method of manufacturing the same.

(Prior art) Generally, power transmission belts such as a V-belt and a timing belt are made of rubber or a polymer compound. When the belt runs, static electricity is generated due to friction between the belt and the pulley, and the belt is charged. The user is in danger of receiving a strong electric shock due to contact with a belt or the like.

Therefore, the belt used for the device that does not like the generation of static electricity is antistatic by mixing conductive carbon such as acetylene black and furnace black into the rubber compound. The belt is worn by contact and rubbing, and the abrasion powder scatters around the apparatus, and stains the apparatus, or the black appearance of the belt deteriorates the color appearance and lowers the commercial value of the conveyed goods. And the like.

On the other hand, antistatic means using no conductive carbon include: (1) a method of bonding conductive powder to a tensile member of a belt. (No. 50-18032) (2) A method of wrapping a metal foil around the surface of the tensile member.

(3) A method of mixing carbon fibers or metal fibers on the surface or inside the elastic body of the belt. (Japanese Utility Model Publication No. 46-25698) are known.

(Problems to be Solved by the Invention) However, since the tension-containing belts of the above (1) and (2) have little expansion and contraction, if the device has a fixed pulley shaft and no belt tension adjusting means, the belt tension may be reduced. If the belt tension is low, the belt slips and the service life is remarkably shortened.If the belt tension is large, noise may be generated. When it is extremely large, there are disadvantages such as damage to the bearing.

In the case of the above (3), the fibers are sheared by the stress generated during kneading of the elastic body, and the conductive function is reduced by half.
It is necessary to use a large amount of conductive fiber to be lost, but if a large amount of conductive fiber is mixed in the elastic body, the function as an elastic body is significantly impaired, which leads to a decrease in the function as a belt, It also results in extremely shortened belt life.

The present invention has been made in view of the above-described circumstances, and as a result of intensive studies to solve the disadvantages, the present invention focuses on the method of mixing conductive materials, and the belt is a rubber belt without a core, and the belt has elasticity and antistatic properties. It is an object of the present invention to provide an antistatic rubber belt which uses a small amount of a conductive substance in order to have the same function and not to lose the elastic function of rubber, and to provide a method of manufacturing the same.

(Means for Solving the Problems) In order to achieve the above object, a first feature of the present invention is a rubber belt made of an endless elastic body without a core or a cover cloth, wherein the elastic body is non-conductive. The antistatic rubber belt has at least a two-layer structure of a conductive elastic body and a thin-film conductive elastic body, and the conductive substance in the conductive elastic body is a cut product of a needle-like product.

And the cut length of the conductive material is 0.03-0.5mm
Of the range.

Next, the second feature of the present invention is that the unvulcanized rubber and the solvent are mixed at a weight ratio of about 1: 1 and the unvulcanized rubber is swollen, and then the solvent is added as appropriate. After stirring to form a solution having a predetermined viscosity, the necessary amount of conductive material was mixed and dispersed, and then applied to a uniform thickness on release paper, and the solvent was evaporated. Dry to form a thin conductive unvulcanized rubber sheet, wrap it with the non-conductive unvulcanized rubber sheet around the outer surface of the cylindrical mold, and heat and press to form an endless antistatic rubber. This is a method for producing an antistatic rubber belt in which a sleeve is formed and then cut to an appropriate width to form an antistatic rubber belt. The solution viscosity of the elastic body when the conductive substance is mixed and dispersed is 30 to 70,000 cp.

(Examples) Specific examples of an antistatic rubber belt and a method for manufacturing the same according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a partial perspective view of a transmission flat belt 1 entirely made of rubber without a tension member as an example of an antistatic rubber belt according to a first feature of the present invention. This is a flat belt having a three-layer structure in which thin conductive elastic layers 3 and 3 are stacked on top and bottom. In the above configuration, the conductive elastic layer 3 is a feature of the present invention, and is formed of natural rubber (N
R), styrene-butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), hydrogenated styrene-butadiene rubber (HSBR)
With respect to 100 parts by weight of a single material such as a single material or a rubber obtained by appropriately blending them, a conductive fiber made of an acicular product of a metal oxide such as aluminum oxide and zinc oxide has a length of 0.03 to 5.
It is composed of a mixture of 10 to 40 parts by weight of the conductive material 4 cut to 0 mm. In general, the thickness of the conductive elastic layer 3 is preferably thinner because it is bent on the pulley. In general, the thickness is preferably 0.01 to 0.1 mm, since the whiteness of the image is reduced or the white color cannot be maintained.

When the amount of the conductive substance 4 is less than 10 parts by weight, the conductive function is not sufficient. When the amount of the conductive substance is 40 parts by weight or more, the conductive function is constant and good. Function is significantly impaired. Further, when the length of the conductive material is less than 0.03 mm, the conductive function is halved, and when the length is more than 5.0 mm, there is a problem that it cannot be uniformly mixed into rubber.

Next, a method for manufacturing the antistatic rubber belt according to the second aspect of the present invention will be described. First, NR, SBR, CR, NB
Unvulcanized rubber compound is made by kneading silica, sulfur, vulcanizing agent, vulcanizing aid and other compounding agents as a reinforcing material into a single material such as R, HNBR, HSBR, etc. I do. This unvulcanized rubber compound was mixed with a solvent at a weight ratio of 1: 1 to swell the unvulcanized rubber compound to facilitate dissolution, followed by stirring to completely dissolve the unvulcanized rubber. After that, the solvent was added sequentially, and the solution viscosity was 30 ~ with a JISB type viscometer.
Prepare a rubber solution in the range of 70,000 centipoise (hereinafter referred to as cp). When the solution viscosity is less than 30 cp, a thin film sheet in which the conductive substance is homogeneously dispersed due to precipitation or floating of the conductive substance due to a too large difference in specific gravity between the conductive substance and the solvent described later. I can't get it.

On the other hand, if the solution viscosity is 70,000 cp or more, the conductive substance is destroyed by the stress generated during stirring, not only impairing its function, but also dispersing the conductive substance inhomogeneously or increasing the thickness when processing the thin film sheet in the subsequent process There are problems such as difficulty in obtaining a good thin film sheet due to non-uniformity and non-uniform dispersion of the conductive substance.

Next, while stirring the rubber solution within the above solution viscosity range, aluminum oxide, acicular products of metal oxides such as zinc oxide or metal fibers, conductive fibers such as carbon fibers, the length of which is 0.03 to 5.0 mm. Of conductive material 4 in rubber 100 in solution
Mix and disperse 10 to 40 parts by weight with respect to parts by weight. At this time, the conductive substance has low strength, is brittle and easily breaks, and if the shape is damaged, the conductivity is impaired.

Further, a rubber solution in which the conductive substance 4 is homogeneously dispersed is applied on release paper to a uniform thickness using, for example, a doctor knife, and the solvent is evaporated to a certain degree.
(Approximately ° C.) and gradually dried while being attached to the surface of a heating roll to form a thin conductive unvulcanized rubber sheet.

Then, on the outer peripheral surface of the cylindrical mold D, the thin-film conductive unvulcanized rubber sheet 13 and the non-conductive unvulcanized rubber sheet 12 obtained above, and further, the thin-film conductive unvulcanized rubber sheet 13 Are sequentially wound, heated and pressurized at a predetermined temperature and a predetermined pressure by a known method to form a cylindrical vulcanized rubber sleeve, and cut to a required width as appropriate to obtain an endless antistatic rubber belt 1. .

(Effects) As described above, the antistatic rubber belt and the method of manufacturing the same according to the present invention provide a method for forming a conductive elastic layer by uniformly and electrically conducting a conductive substance in a rubber solution having a predetermined viscosity range. A conductive elastic material that can be dispersed without damaging the shape of the conductive material and is even more uniform in dispersion of the conductive material and thinner and thinner than the conventional method of mixing conductive material into rubber by kneading. Can be made.

In addition, the antistatic belt according to the present invention does not contain carbon black in the conductive elastic body, so there is no need to worry about dirt, and since it does not have a tensile body, it fits the pulley sufficiently with a small mounting tension, The pulley shaft can be made thinner, and further, the color of the belt can be freely changed to a color other than black in accordance with the transmission device, so that the commercial value can be improved in appearance.

[Brief description of the drawings]

FIG. 1 is a partial perspective view of an antistatic rubber belt according to the present invention, FIG. 2 is a plan view of a conductive elastic sheet which is a part of the configuration of the antistatic rubber belt, and FIG. It is a fragmentary longitudinal cross-sectional view which shows the outline of the manufacturing process of a vulcanized rubber sleeve. DESCRIPTION OF SYMBOLS 1 ... Antistatic rubber belt 2 ... Non-conductive elastic sheet 3 ... Conductive elastic sheet 4 ... Conductive substance 12 ... Non-conductive unvulcanized rubber sheet 13 ... Conductive unvulcanized Rubber sheet

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-103132 (JP, A) JP-A-59-109323 (JP, A) JP-A-61-273919 (JP, A) 110854 (JP, U) Shokai Sho 59-58228 (JP, U) Japanese Patent Publication No. 47-14525 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16G 1/00-5 / 20 B29D 29/00-29/10

Claims (3)

(57) [Claims] 1. A rubber belt comprising an endless elastic body without a core or a cover cloth, wherein the elastic body has at least a two-layer structure of a non-conductive elastic body and a thin-film conductive elastic body,
The antistatic rubber belt, wherein the conductive substance in the conductive elastic body is a cut product of a needle-like product having a length of 0.03 to 0.5 mm. 2. An unvulcanized rubber and a solvent are mixed at a ratio of about 1: 1 by weight, and after swelling the unvulcanized rubber, the mixture is stirred while appropriately adding a solvent to form a solution having a predetermined viscosity. After the required amount of conductive material is mixed and dispersed, it is applied on a release paper to a uniform thickness and then dried along the roll surface heated to 80 ° C while evaporating the solvent. After forming an unvulcanized rubber sheet, wrapping this around the outer peripheral surface of the mold on the cylinder together with the non-conductive unvulcanized rubber sheet, heating and pressurizing to form an endless antistatic rubber sleeve, and then appropriately adjusting the width A method for producing an antistatic rubber belt, comprising: forming an antistatic rubber belt. 3. The antistatic rubber belt according to claim 3, wherein the solution viscosity of the elastic body before mixing and dispersing the conductive substance is 30 to 70,000 cp.