JP2009227859A - Rubber molded product, and method for producing rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably achieve a rubber composition having excellent physical characteristics such as abrasion resistance. <P>SOLUTION: A rubber molded product is a rubber molded product having a rubber layer as an object, and the rubber layer comprises a polymer, and a filler dispersed in the polymer. The filler is at least one of carbon black, clay, and silica which have been irradiated with plasma. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubber molded product and a method for producing a rubber composition, and more particularly to a transmission belt, a conveyor belt, and a method for producing the same.

  Currently, rubber molded products are used in various fields. The properties of the rubber molded product are determined not only by the polymer but also by various additives such as fillers and crosslinking agents. Among them, the filler greatly affects the properties of the rubber molded product. Further, not only the physical and chemical properties of the filler, but also how the filler is dispersed in the polymer greatly affects physical properties such as tensile properties, compression properties and hardness of the rubber molded product. Since these physical characteristics determine the wear resistance and bending fatigue resistance of the rubber molded product, the dispersibility of the filler is an important factor determining the product life of the rubber molded product.

  The dispersibility of the filler is determined by various factors such as the particle size, shape and surface state of the filler. Especially, since the surface state of the filler greatly affects the compatibility with the polymer, the dispersibility of the filler is particularly greatly changed. The surface state of the filler is basically determined by the material of the filler, but it has also been studied to positively impart the necessary characteristics by modifying the surface of the filler.

  For example, even when carbon black is blended by modifying the surface of carbon black with silica, a method for realizing viscoelastic properties comparable to silica has been studied (for example, see Patent Document 1).

  Further, a method for improving the reinforcing property of silica by modifying the surface of silica with a vinyl monomer has been studied (for example, see Patent Document 2).

Furthermore, improving the reactivity with a silane coupling agent by plasma-treating silica to improve the reinforcing property has been studied (for example, see Patent Document 3). By blending such a surface-modified filler, it is expected that a rubber molded article having excellent characteristics will be realized.
Japanese Patent Laid-Open No. 10-25428 JP 2006-273588 A JP 2007-106888 A

  However, the conventional surface-modified filler has the following problems. First, when the surface of the filler is chemically modified, batch processing is necessary, so that variation from batch to batch becomes a serious problem. Due to the slight difference in the surface treatment state, the characteristics of the rubber composition containing the filler vary greatly. For this reason, it is difficult to supply a stable product.

  In the case of plasma processing, continuous dry processing is possible, and it is possible to eliminate the influence of variation from batch to batch. However, the conventional plasma treatment for the filler is intended to improve the reactivity between silica and the silane coupling agent. For this reason, it has not been examined how the plasma irradiation affects the dispersibility of the filler.

  The object of the present invention is to solve the above-mentioned conventional problems, improve the dispersibility of the filler, and stably realize a rubber molded product excellent in physical properties such as wear resistance.

  In order to achieve the above object, the present invention has a rubber molded article having a rubber layer in which a filler irradiated with plasma is dispersed.

  Specifically, the rubber molded article according to the present invention is intended for a rubber molded article provided with a rubber layer, the rubber layer includes a polymer and a filler dispersed in the polymer, and the filler is carbon irradiated with plasma. It is at least one of black, clay and silica.

The rubber molded product of the present invention includes a rubber layer in which a filler irradiated with plasma is dispersed. For this reason, the dispersibility of the filler in the rubber layer is excellent, and the physical characteristics of the rubber layer are greatly improved. Therefore, it is possible to stably realize a rubber molded article excellent in wear resistance, bending fatigue resistance, etc. In the rubber molded article of the present invention, the filler is kneaded with the polymer in the presence of a supercritical fluid. It may be dispersed.

  In the rubber molded article of the present invention, the filler may be irradiated with plasma at atmospheric pressure.

  The rubber molded product of the present invention further includes a reinforcing layer bonded to the rubber layer, and may be molded as a transmission belt or a conveyor belt.

  The method for producing a rubber composition according to the present invention includes a step (a) of forming a plasma-treated filler by irradiating the filler with plasma, and a step (b) of kneading the plasma-treated filler and a polymer. It is characterized by that.

  The method for producing a rubber composition of the present invention includes a step of irradiating a filler with plasma. For this reason, kneading | mixing of a polymer and a filler is easy and the rubber composition excellent in the dispersibility of a filler can be obtained. Therefore, it is possible to stably realize a rubber molded product having excellent wear resistance and bending fatigue resistance.

  In the method for producing a rubber composition of the present invention, in the step (b), kneading may be performed in the presence of a supercritical fluid. In this case, the supercritical fluid may be carbon dioxide or nitrogen.

  In the method for producing a rubber composition of the present invention, the step (a) includes a step of pulverizing an agglomerate contained in the filler by charging the filler, and a step of irradiating plasma on the filler in which the agglomerate is crushed. It is good also as a structure containing.

  In the method for producing a rubber composition of the present invention, plasma irradiation may be performed at atmospheric pressure.

  In the method for producing a rubber composition of the present invention, the filler may be at least one of carbon black, clay and silica.

  According to the rubber composition and the method for producing the same according to the present invention, a rubber composition having improved filler dispersibility and excellent physical properties such as wear resistance can be stably realized.

  The rubber composition according to the present embodiment contains a plasma-treated filler. The plasma treatment improves the compatibility between the filler and the polymer and improves the dispersibility of the filler. As a result, physical properties such as wear resistance of the rubber composition are greatly improved.

-Plasma treatment process-
The filler for performing the plasma treatment may be any as long as it is kneaded in a normal rubber composition. For example, carbon black, silica, clay, calcium carbonate, talc, titanium oxide, mica, diatomaceous earth, wollastonite, zeolite, bituminous fine powder, quartz sand, pumice powder, slate powder, alumina, aluminum sulfate, barium sulfate, lithopone, Calcium sulfate, magnesium oxide, molybdenum disulfide, graphite, glass fiber, glass ball, glass hollow body, carbon fiber, carbon hollow body anthracite powder, cryolite, silicone resin fine powder, spherical silica fine particle, aramid short fiber and alumina short fiber Etc.

  Examples of the carbon black used as the filler include channel black; furnace black such as SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF or N-234; FT or MT Thermal black; acetylene black etc. are mentioned. The amount of carbon black added is preferably 5 to 130 parts by mass with respect to 100 parts by mass of the polymer.

  Examples of clay include layered clay minerals and organic clay minerals. Moreover, the addition amount should just be 5 mass parts-40 mass parts with respect to 100 mass parts of polymers.

Silica may be obtained by various methods such as a sol-gel method, a wet method, and a dry method. In particular, wet silica is preferred from the viewpoints of the reinforcing effect, low heat build-up, and friction characteristics when wet. Although the microstructure of the silica is not particularly limited, a nitrogen absorption specific surface area from increasing the interaction between the rubber molecules (BET) is 100cm ² / g~300m ² / g, a DBP oil absorption of 150ml / 100g~300ml / 100g Some are preferred. Moreover, the addition amount should just be about 5 mass parts-70 mass parts with respect to 100 mass parts of polymers.

  The plasma treatment may be performed by irradiating plasma using gas species such as air, oxygen, nitrogen, fluorine-containing gas, and rare gas such as argon, helium, or neon. Moreover, these mixed gas may be sufficient. The plasma generation atmosphere may be atmospheric pressure or reduced pressure. The plasma may be generated by glow discharge, corona discharge, spark discharge, or the like.

  In addition, continuous plasma irradiation can reduce the variation between batches and provide more stable characteristics.

  Furthermore, in order to uniformly plasma-treat the filler surface, it is preferable to perform plasma irradiation after crushing the agglomerates in the filler. Crushing may be performed, for example, by charging the filler particles with electrostatic ions and repelling the filler particles.

  Plasma irradiation to the filler may be performed using any apparatus. For example, if an apparatus as shown in FIG. 1 is used, continuous and uniform plasma treatment can be performed. The plasma irradiation apparatus shown in FIG. 1 continuously processes fillers in a cylindrical heating furnace 30 installed in a chamber 20. The plasma 21 is generated using a plasma generation tube 31 provided with an induction coil 32. A high frequency power source 33 is connected to the induction coil 32 via a matching circuit 34. The generation state of the plasma 21 can be monitored by the radical amount sensor 51.

  An introduction tube 35 is connected to one end of the plasma generation tube 31, and the filler 23 supplied from the filler supply device 40 is continuously introduced into the plasma generation tube 31, and plasma irradiation is performed. The filler 24 irradiated with plasma is discharged from the other end of the plasma generation tube 31 and collected in a collection container 53.

  When introducing the filler into the introduction pipe 35, gas ionized by the ionizer 45 is used. Thereby, the filler particles are charged, and an electrostatic repulsive force is generated between the filler particles. As a result, the filler particles are in a state of being crushed approximately every one particle, and uniform plasma treatment can be performed. In addition, a weighing device 49 is connected to the filler supply device 40, and the amount of filler supplied and the like can be managed.

  The type of plasma gas generated in the plasma generation tube 31 can be arbitrarily set by changing the gas supplied through the valve 52. Further, the chamber 20 is provided with a gas supply port 26 and an exhaust port 27, and the chamber 20 can be filled with a predetermined gas.

-Kneading process-
The plasma treatment filler formed in the plasma treatment step may be kneaded with the polymer by a known rubber kneading method. At this time, a single type of plasma processing filler may be kneaded or a plurality of types of plasma processing filler may be kneaded.

  Examples of polymers that are uncrosslinked rubbers include natural rubber (NR), styrene butadiene rubber (SBR), isoprene rubber (IR), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), and chloroprene rubber (CR). , Ethylene-α-olefin copolymer rubber (for example, EPDM, EPR, etc.), butyl rubber (IIR), acrylic rubber (ACM), chlorosulfone or polyethylene rubber (CSM), silicone rubber (Q), fluorine rubber (FKM) And urethane rubber (U). As the raw rubber, only a single type may be used, or a plurality of types may be mixed and used.

  The polymer may be in the form of powder, may be granular, and may be in the form of pellets.

  Further, in the kneading step, other compounding agents such as a cross-linking agent, an anti-aging agent, a plasticizer and a cross-linking accelerator other than the plasma treatment filler may be appropriately mixed.

  Examples of the crosslinking agent include sulfur, sulfur compounds, oximes, nitroso compounds, polyamines, and organic peroxides. Only one kind of the crosslinking agent may be used, or a plurality of kinds may be mixed and used. The addition amount of the crosslinking agent is preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the raw rubber. In addition, when performing the process which does not use crosslinking agents, such as electron beam crosslinking, at a shaping | molding bridge | crosslinking process, a crosslinking agent is not necessarily required.

  Examples of the anti-aging agent include amine-based, quinoline-based, hydroquinone derivatives, monophenol-based, polyphenol-based, thiobisphenol-based, hindered phenol-based, and phosphite-based compounds. Only one type of anti-aging agent may be used, or a plurality of types may be used in combination. The addition amount of the antioxidant is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the raw rubber.

  Examples of the plasticizer include phthalic acid derivatives, isophthalic acid derivatives, tetrahydrophthalic acid derivatives, adipic acid derivatives, azelaic acid derivatives, sebacic acid derivatives, dodecane-2-acid derivatives, maleic acid derivatives, fumaric acid derivatives, trimellitic acid. Derivatives, pyromellitic acid derivatives, citric acid derivatives, itaconic acid derivatives, oleic acid derivatives, ricinoleic acid derivatives, stearic acid derivatives, sulfonic acid derivatives, phosphoric acid derivatives, glutaric acid derivatives, glycol derivatives, glycerin derivatives, paraffin derivatives, epoxy derivatives Etc. Only one kind of plasticizer may be used, or a plurality of kinds may be mixed and used. The addition amount of the plasticizer is preferably 5 to 100 parts by mass with respect to 100 parts by mass of the raw rubber.

  Examples of the crosslinking accelerator include guanidine, aldehyde-amine, aldehyde-ammonia, thiazole, sulfenamide, thiourea, thiuram, dithiocarbamate, and xanthate. As the crosslinking accelerator, only one kind may be used, or a plurality of kinds may be mixed and used. The addition amount of the crosslinking accelerator is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the raw rubber.

  When the filler is silica, a silane coupling agent may be blended. Examples of the silane coupling agent include sulfide systems such as bis- (3- (triethoxysilyl) propyl) polysulfide (S number of polysulfide moiety: 2 to 8), mercapto systems such as 3-mercaptopropyltrimethoxysilane, 3- Examples include silane coupling agents used for ordinary rubbers of amino type such as aminopropyltrimethoxysilane and vinyl type such as vinyltriethoxysilane. A silane coupling agent may use only a single kind, and may mix and use multiple types. The addition amount of the silane coupling agent is preferably 0.5 to 15 parts by mass with respect to 100 parts by mass of the rubber component. When kneading using a supercritical fluid, which will be described later, an effect of further enhancing the interaction between the polymer and the filler can be obtained by adding a silane coupling agent.

  Kneading may be performed using a roll, a biaxial extrusion kneader or the like. Further, kneading conditions such as kneading time may be appropriately set based on the rubber compounding composition and the like.

  The order of kneading is not particularly defined. Moreover, all the compounding agents may be kneaded at once or may be kneaded in several times. For example, the cross-linking agent may be kneaded after kneading the plasma treatment filler excluding the cross-linking agent, the cross-linking accelerator and the anti-aging agent. Moreover, you may knead | mix a plasma processing filler to the polymer which added compounding agents other than the plasma processing filler previously.

  The plasma-treated filler exhibits excellent dispersibility even when kneaded by an ordinary kneading method. However, if the kneading is performed in the presence of a supercritical fluid or subcritical fluid as shown below, the dispersibility is further increased. Will improve.

  A supercritical fluid refers to a fluid in a supercritical state. The supercritical state refers to a state where the temperature is equal to or higher than the critical temperature (Tc) of the fluid and the pressure is equal to or higher than the critical pressure (Pc) of the fluid.

  A subcritical fluid refers to a fluid in a subcritical state. A subcritical state is a state where only one of temperature and pressure reaches a critical state and the other does not reach a critical state, or both temperature and pressure do not reach a critical state, but at least one of temperature and pressure Is a state that is sufficiently higher than room temperature and normal pressure and close to the critical state. In the present application, the subcritical state is defined as 0.5 <T / Tc <1.0 and 0.5 <P / Pc, or 0.5 <T where temperature is T (Celsius) and pressure is P. A state where T / Tc and 0.5 <P / Pc <1.0 are satisfied.

  Preferred subcritical states for rubber kneading are 0.6 <T / Tc <1.0 and 0.6 <P / Pc, or 0.6 <T / Tc and 0.6 <P / Pc <1. This is a state that satisfies the condition of 0. When the critical temperature Tc (Celsius) is negative, the temperature condition is satisfied. If the supercritical condition is not satisfied and the pressure condition of 0.5 <P / Pc is satisfied, the subcritical state is obtained. It shall be.

  Examples of the substance that generates the supercritical fluid or subcritical fluid include carbon dioxide, nitrogen, hydrogen, xenon, ethane, ammonia, methanol, and water. Of these, carbon dioxide and nitrogen are suitable for rubber kneading.

  Carbon dioxide has a critical temperature (Tc) of 31.1 ° C. and a critical pressure (Pc) of 7.38 MPa. Therefore, supercritical carbon dioxide is carbon dioxide in a state where the temperature T is 31.1 ° C. or higher and the pressure P is 7.38 MPa or higher. Subcritical carbon dioxide is carbon dioxide in a state satisfying the conditions of 15.6 ° C. <T <31.1 ° C. and 3.69 MPa <P, or 15.55 ° C. <T and 3.69 MPa <P <7.38 MPa. It is.

  The critical temperature (Tc) of nitrogen is −147.0 ° C., and the critical pressure (Pc) is 3.40 MPa. Therefore, the supercritical nitrogen is nitrogen in a state where the temperature T is −147.0 ° C. or higher and the pressure P is 3.40 MPa or higher. Subcritical nitrogen is nitrogen that does not satisfy the condition of supercritical nitrogen and satisfies the condition of 1.70 MPa <P.

  In the presence of a supercritical fluid or a subcritical fluid, other liquids or gases may coexist within a range that does not hinder rubber kneading.

  For kneading rubber in the presence of such supercritical fluid or subcritical fluid, a kneading member such as a rotor, kneading disk or screw is provided in a sealed rubber kneading chamber having excellent heat resistance and pressure resistance. This can be done by using a kneader. The kneading apparatus is a continuous type that continuously supplies the polymer and filler and discharges the filler-containing uncrosslinked rubber composition, such as a twin-screw extrusion kneading apparatus disclosed in JP-A-2002-355880, etc. Is preferred.

  When the rubber is kneaded in the presence of the supercritical fluid or subcritical fluid, the polymer and the additive are dissolved in the supercritical fluid or subcritical fluid and mechanically stirred and kneaded by the kneading member.

  In the kneading step, after kneading the compounding agent excluding the polymer, filler, and cross-linking agent in the presence of a supercritical fluid or subcritical fluid, the obtained kneaded product is cross-linked with the same kneading device or another kneading device. An uncrosslinked rubber composition containing a crosslinking agent may be prepared by further kneading the agent. Thus, by adding a crosslinking agent after kneading in the presence of a supercritical fluid or subcritical fluid, it is possible to prevent the progress of the crosslinking reaction during kneading in the presence of the supercritical fluid or subcritical fluid. it can.

  In the kneading step, after kneading the polymer and filler in the presence of a supercritical fluid or subcritical fluid, the kneading obtained using the same kneading device or another kneading device, for example, a single screw extruder An uncrosslinked rubber composition may be prepared by kneading the product and another compounding agent containing a crosslinking agent.

  In any case, using the same kneading apparatus, it is possible to perform a series of operations from the introduction of raw materials to the preparation of an uncrosslinked rubber composition containing a crosslinking agent.

  In addition, before kneading in the presence of a supercritical fluid or subcritical fluid, it is preferable to knead the polymer and filler in advance and plasticize, and after kneading in the presence of a supercritical fluid or subcritical fluid. It is preferable to deaerate the kneaded product.

-Crosslinking step-
The uncrosslinked rubber composition obtained by the kneading process is molded and crosslinked by a normal molding and crosslinking process, whereby a crosslinked rubber composition is obtained.

  Examples of molding cross-linking processing methods include press, vulcanizing can, continuous vulcanizer, processing using a special cross-linking machine that cross-links by high-frequency cross-linking, radiation cross-linking or electron beam cross-linking, transfer molding, injection molding, extrusion molding, Examples include injection molding.

  The molding crosslinking conditions such as temperature, pressure, and time are appropriately set based on the composition of the filler-containing uncrosslinked rubber, the required quality of the rubber molded product, and the like.

  In the molding and crosslinking step, the polymer molecules contained in the uncrosslinked rubber composition are crosslinked with a crosslinking agent or an electron beam to form a network structure. Thereby, a crosslinked rubber composition is obtained.

  The molding and crosslinking step may be performed according to the type of rubber molded product to be manufactured. For example, when manufacturing a V-ribbed belt having a rubber layer and a reinforcing layer as shown in FIG. do it.

  The V-ribbed belt B includes a V-ribbed belt main body 10 configured as a double layer of an adhesive rubber layer 11 on the belt outer peripheral side and a compression rubber layer 12 on the belt inner peripheral side, and the belt outer peripheral surface of the V-ribbed belt main body 10. A reinforcing cloth 17 is affixed to. Further, a core wire 16 is embedded in the adhesive rubber layer 11 so as to form a spiral having a pitch in the belt width direction.

  The adhesive rubber layer 11 is formed in a band shape having a horizontally long cross section, and is formed to have a thickness of 1.0 to 2.5 mm, for example.

  The adhesive rubber layer 11 is formed of a cross-linked rubber in which a raw rubber is mixed with various rubber compounding agents and kneaded and kneaded, and the uncross-linked rubber is heated and pressurized and cross-linked by a cross-linking agent.

  The compression rubber layer 12 is provided so that a plurality of V ribs 13 constituting the pulley contact portion hang down to the belt inner peripheral side. Each of the plurality of V ribs 13 is formed in a ridge having a substantially inverted triangular cross section extending in the belt length direction, and arranged in parallel in the belt width direction. Each V rib 13 is formed, for example, with a rib height of 2.0 to 3.0 mm and a width between base ends of 1.0 to 3.6 mm. The number of ribs is, for example, 3 to 6 (in FIG. 2, the number of ribs is 6).

  The compressed rubber layer 12 is formed of a crosslinked rubber in which a filler-containing uncrosslinked rubber composition obtained by kneading a polymer with a filler and various rubber compounding agents is heated and pressurized and crosslinked with a crosslinking agent or the like. The compressed rubber layer 12 may include short fibers 14 that are provided so as to be oriented in the belt width direction and that protrude from the surface of the V rib 13. Examples of the short fibers 14 include nylon short fibers having a fiber length of 1 to 3 mm, vinylon short fibers, polyester short fibers, cotton short fibers, and aramid short fibers.

  The adhesive rubber layer 11 and the compressed rubber layer 12 may be formed of separate crosslinked rubbers, or may be formed of the same crosslinked rubber. If at least one of the adhesive rubber layer 11 and the compressed rubber layer 12 is molded from the rubber composition of the present embodiment, a transmission belt having excellent wear resistance can be realized.

  The reinforcing cloth 17 is composed of, for example, a woven cloth woven into plain weave, twill weave, satin weave or the like formed of yarn such as cotton, polyamide fiber, polyester fiber, and aramid fiber. In order to give the reinforcing cloth 17 adhesion to the V-ribbed belt main body 10, an adhesive treatment in which it is immersed in an RFL aqueous solution and heated before molding and / or a surface of the V-ribbed belt main body 10 is coated with rubber paste. Adhesive treatment for drying is applied. In addition, the reinforcing cloth 17 may not be provided, and the belt outer peripheral side surface portion may be made of a crosslinked rubber. Further, the reinforcing cloth 17 may be formed of a knitted fabric.

  The core wire 16 is composed of a twisted yarn such as polyester fiber (PET), polyethylene naphthalate fiber (PEN), aramid fiber, vinylon fiber or the like. In order to give the core wire 16 adhesion to the V-ribbed belt main body 10, an adhesive treatment for heating after being immersed in an RFL aqueous solution before molding and / or an adhesive treatment for drying after being immersed in rubber paste is performed. .

  In addition to the V-ribbed belt, other types of power transmission belts such as a flat belt and a toothed belt can be formed in the same manner.

  A conveyor belt can be formed by laminating a rubber layer and a reinforcing layer made of fiber or metal. FIG. 3 shows an example of a conveyor belt.

  The conveyor belt has a canvas layer 63 as a central layer, and adhesive rubber layers 61 are provided on both sides thereof. A cover rubber layer 62 and a back cover rubber layer 64 are provided on the upper and lower outermost layers of the conveyor belt, respectively. Since the cover rubber layer 62 and the back cover rubber layer 64 are particularly required to have abrasion resistance, if at least one of these layers is molded from the rubber composition of this embodiment, a conveyor belt having excellent abrasion resistance can be obtained. can get. The cover rubber layer 62 and the back cover rubber layer 64 may be one layer, or two or more layers of the same or different rubber compositions may be laminated. Further, the cover rubber layer 62 and the back cover rubber layer 64 may have the same configuration or different configurations.

  The rubber composition used for the adhesive rubber layer 61 is not particularly limited, and a rubber composition used for a normal conveyor belt may be appropriately selected and used. The canvas layer 63 is not particularly limited, and a material used for a normal conveyor belt may be appropriately selected and used. For example, those made of cotton cloth and chemical fiber or synthetic fiber with rubber paste applied and infiltrated, those obtained by folding RFL treatment, special woven nylon canvas, steel cord, and the like can be mentioned. The canvas layer 63 may be used alone, or two or more types may be laminated and used.

  The manufacturing method of a conveyor belt is not specifically limited, The method etc. which are normally used should just be employ | adopted. For example, first, the rubber composition is preformed into a sheet shape, and vulcanized by pressurizing at a temperature of 150 ° C. to 170 ° C. for 10 minutes to 60 minutes to produce each layer such as a cover rubber layer. Next, an abrasion-resistant conveyor belt can be manufactured by laminating the obtained layers on a canvas in a predetermined order.

  Hereinafter, the rubber composition and the production method thereof according to the present invention will be described in more detail with reference to examples.

<First embodiment>
As shown in Table 1, six types of rubber compositions A to F with different types of plasma treatment fillers and different kneading methods were prepared. Moreover, as a comparative example, 6 types of rubber compositions G to L were prepared by blending a filler not subjected to plasma treatment.

  As the polymer, pellet-shaped EPDM (trade name: Nodel 4725P, manufactured by DuPont Dow Elastomer Japan Co., Ltd.) was used.

  To rubber compositions A and B, 70 parts by mass of plasma-treated carbon black (HAF grade, Tokai Carbon Co., Ltd., trade name: Seast 3) was added as a filler. To the rubber compositions G and H, 70 parts by mass of carbon black not subjected to plasma treatment was added.

  To the rubber compositions C and D, 10 parts by mass of plasma-treated clay (trade name: Sven NX manufactured by Hojun Co., Ltd.) was added. To the rubber compositions I and J, 10 parts by mass of clay that was not plasma-treated was added.

  To rubber compositions E and F, 70 parts by mass of plasma-treated silica (trade name: Nipsil VN3 manufactured by Tosoh Silica Co., Ltd.) was added. To rubber compositions K and L, 70 parts by mass of silica not subjected to plasma treatment was added.

  As a common component in rubber compositions A to L, 5 parts by mass of zinc oxide (trade name: 3 types of zinc oxide manufactured by Sakai Chemical Industry Co., Ltd.) and 1 part by mass of stearic acid (product name: manufactured by Shin Nippon Rika Co., Ltd.) 50S), 5 parts by mass of process oil (trade name: Samper 2280, manufactured by Nippon San Oil Co., Ltd.), 1.2 parts by mass of a crosslinking accelerator (trade name: Nouchira PZ, manufactured by Ouchi Shinsei Chemical Co., Ltd.) and 1.67 parts by mass. The cross-linking agent (trade name: oil sulfur manufactured by Tsurumi Chemical Co., Ltd.) was blended. Further, 8 parts by mass of a silane coupling agent (trade name: Si69, manufactured by Degussa) was blended with the rubber compositions G and O blended with silica.

  The plasma irradiation was performed using the continuous atmospheric pressure plasma irradiation apparatus shown in FIG. 1 so that the agglomerates were crushed by charging the filler so that the plasma was irradiated in a state where the filler particles were dispersed. .

  For the kneading of each rubber composition, a twin-screw extrusion kneader (manufactured by Nippon Steel Co., Ltd., model number: TEX30α) was used. Further, the rubber compositions B, D, F, H, J and L were kneaded in the presence of a supercritical fluid.

  The biaxial kneading apparatus used in this example is provided with a long rubber kneading chamber, and a raw material supply unit and a kneading rubber discharge unit are provided at the upstream end and the downstream end, respectively. In the rubber kneading chamber, a pair of screws each having an outer diameter of 30 mm and a length ratio to the outer diameter of 59.9 are provided in parallel along the length direction. Is divided into 17 cylinders C1 to C17.

  In addition, a water-cooling temperature control mechanism is provided in the cylinder C1 directly below the raw material supply unit, thereby preventing the raw material from melting. In addition, a temperature control mechanism is provided in each of the other cylinders C2 to C17, so that independent heating and cooling are possible. A gas supply pipe is connected to the cylinder C7.

  In the kneading, the rotation speed of the screw is 200 rpm, the supply amount of carbon dioxide from the gas supply pipe to the cylinder C7 is 0.5 kg / hour, the pressure of the cylinders C11 and 12 is 1.73 Pa, and the extrusion discharge amount of the uncrosslinked rubber composition is Each setting was performed at 6 kg / hour. Further, by operating the configuration of the reverse kneading disk and the seal ring and the set temperature of the cylinders C7 to C10, the inside of the cylinders C7 to C10 was made to be in the presence condition of supercritical carbon dioxide having a temperature of 120 ° C. and a pressure of 9 MPa. . The temperature is the temperature of the kneaded material in the cylinders C7 to C10, and the pressure is the pressure in the cylinder C10.

  In this example, the material kneaded and plasticized in the cylinders C1 to C6 was further kneaded in the cylinders C7 to C10 in the presence of supercritical carbon dioxide. In the cylinders C7 to C10, kneading was performed without adding a crosslinking agent and a crosslinking accelerator. The crosslinking agent and the crosslinking accelerator were added to the kneaded material in the cylinder C15. In the cylinders C15 to C17, the kneaded material further added with the crosslinking agent and the crosslinking accelerator was further kneaded.

  The obtained uncrosslinked rubber composition was molded and cross-linked to a test piece for a frictional wear test. The test piece was in the form of a prism with a 5 mm square and a height of 10 mm. The wear test was conducted using a pin disk type friction wear tester for 24 hours under conditions of a surface pressure of 0.8 MPa, a friction speed of 0.25 m / s, and a friction surface temperature of 100 ° C. against a 5 mm square bottom surface. went. The wear volume was determined by dividing the weight change of the test piece before and after the test by the specific gravity of each sample. Note that gray cast iron (FC200) was used as the mating material.

  As shown in Table 1, in any case of carbon black, clay, and silica, the use of the plasma irradiation filler decreased the wear volume compared to the unirradiated filler, and greatly improved the wear resistance. This is considered to be because the dispersibility of the filler was improved by plasma irradiation. In addition, wear resistance could be further improved by kneading in the presence of a supercritical fluid. This is considered to be because the dispersibility of the filler in the polymer was further improved by the supercritical fluid.

  As the supercritical fluid, nitrogen or the like may be used instead of carbon dioxide. The same effect can be obtained when kneading is performed in the presence of a subcritical fluid instead of the supercritical fluid.

<Second Embodiment>
V-ribbed belts were molded for the three types of rubber compositions M, N and O shown in Table 2, and the wear resistance was evaluated. For the kneading of the rubber composition, the same twin-screw extrusion kneading apparatus as in the first example was used. In addition, plasma irradiation to the filler was performed in the same manner as in the first example.

  The V-ribbed belt had a belt circumferential length of 1000 mm, a belt width of 10 mm, a belt thickness of 4 mm, and three ribs. The rubber compositions M, N, and O preformed into a sheet having a thickness of 0.8 mm were cross-linked to form a compressed rubber layer. As the adhesive rubber layer, a normal EPDM rubber composition and a reinforcing fabric obtained by subjecting a nylon woven fabric to RFL treatment and rubber paste treatment were used. The core wire was obtained by subjecting a polyester fiber (PET) twisted yarn to RFL treatment and rubber paste treatment.

  FIG. 4 shows a pulley layout of a belt running test machine 70 for evaluating the abrasion resistance test of the V-ribbed belt. The belt running test machine 70 includes a pair of driving rib pulleys 71 and driven rib pulleys 72 having a pulley diameter of 60 mm arranged on the left and right sides.

  For each of the molded V-ribbed belts, first, the initial belt belt mass was measured. Next, a V-ribbed belt is wound around the drive rib pulley 71 and the driven rib pulley 72 so that the V-rib side contacts, and the drive rib pulley 71 is pulled to the side so that a dead weight of 1177N is loaded, and a rotational load of 7 W is applied. It applied to the driven rib pulley 72. After carrying out a belt running test in which the drive rib pulley 71 was rotated at a rotational speed of 3500 rpm for 24 hours at room temperature, the belt mass after running was measured, and the wear rate was calculated based on the following equation.

  As shown in Table 2, V-ribbed belts molded from rubber compositions M and N using fillers that were subjected to plasma irradiation were more suitable than V-ribbed belts molded from rubber composition O using fillers that were not plasma-irradiated. The wear rate was small. In addition, the wear rate was smaller when a supercritical fluid was used during kneading. This indicates that the dispersibility of the filler is improved by the plasma irradiation to the filler. Moreover, it became clear that the dispersibility of a filler improves further by combining the plasma irradiation to a filler and the kneading | mixing in presence of a supercritical fluid.

<Third embodiment>
Conveyor belts were molded for the three types of rubber compositions P, Q and R shown in Table 3, and the wear resistance was evaluated. In this example, styrene butadiene rubber (SBR, product name: SBR1500) was used as the polymer, and ISAF grade (product name: N220, Showa Cabot) was used as the carbon black. In addition, a malon indene resin was used as an adhesion-imparting agent, and an amine type (trade name: Nocrack 6C manufactured by Ouchi Shinsei Chemical Co., Ltd.) was used as an anti-aging agent. Oil sulfur manufactured by Tsurumi Chemical Co., Ltd. was used as the crosslinking agent, Noxeller CZ manufactured by Ouchi Shinsei Chemical Co., Ltd. was used as the crosslinking accelerator, and SYNTAC HA30 manufactured by Kobe Oil Chemical Co., Ltd. was used as the oil. For the kneading of the rubber composition, the same twin-screw extrusion kneading apparatus as in the first example was used. In addition, plasma irradiation to the filler was performed in the same manner as in the first example.

  The rubber compositions P, Q and R were used as the cover rubber layer 62 and the back cover rubber layer 64 of the conveyor belt shown in FIG. The thickness of the cover rubber layer 62 was 5 mm, and the thickness of the back cover rubber layer 64 was 3 mm.

  By measuring the thickness of the cover rubber layer after operating the obtained conveyor belt at a speed of 200 m / min so that the ore having a particle size of 50 mm or less is conveyed at a rate of about 800 tons / min. The wear resistance of the belt was evaluated.

  The conveyor belt using the rubber composition R using the filler not irradiated with plasma cracked before 200 hours passed. On the other hand, the conveyor belt using the rubber composition P and Q used with the plasma-irradiated filler did not crack even after 300 hours. Further, the wear amount of the cover rubber layer was small and good wear resistance was shown. This is considered to be because the dispersibility of the filler was improved by plasma irradiation. Further, when the filler irradiated with plasma was kneaded in the presence of a supercritical fluid, even better wear resistance was exhibited.

  In the above embodiment and each Example, the rubber molded product was demonstrated. However, the effect of improving the dispersibility of the filler in the polymer by the plasma irradiation filler can also be obtained in the case of polymers other than rubber. For this reason, wear resistance etc. can be improved not only in a rubber molded product but also in a resin molded product by using a plasma irradiation filler. For example, by applying a plasma irradiation filler to polyphenylene sulfide (PPS), nylon, polyacetal (POM), acrylonitrile butadiene copolymer (ABS) or the like, a resin product such as a precision gear excellent in wear resistance can be realized. Further, if a supercritical fluid is used also in the kneading of the resin and the filler, the dispersibility of the filler can be further improved and the wear resistance and the like can be improved.

  The rubber composition and the production method thereof according to the present invention can stably realize a rubber composition excellent in physical properties such as wear resistance, and in particular, rubber that requires wear resistance such as a transmission belt and a conveyor belt. It is useful as a rubber molded product for realizing a molded product and a manufacturing method thereof.

It is the schematic which shows an example of the plasma irradiation apparatus which concerns on one Embodiment of this invention. It is a perspective view which shows an example of the V-ribbed belt which concerns on one Embodiment of this invention. It is a perspective view which shows an example of the conveyor belt which concerns on one Embodiment of this invention. It is a figure which shows the pulley layout of the belt running test machine in 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 V ribbed belt body 11 Adhesive rubber layer 12 Compression rubber layer 13 V rib 14 Short fiber 16 Core wire 17 Reinforcement cloth 20 Chamber 21 Plasma 23 Filler 24 Filler 26 Gas supply port 27 Exhaust port 30 Heating furnace 31 Plasma generating tube 32 Inductive coil 33 High-frequency power supply 34 Matching circuit 35 Inlet tube 40 Filler supply device 45 Ionizer 49 Weighing device 51 Radical amount sensor 52 Valve 53 Collection container 61 Adhesive rubber layer 62 Cover rubber layer 63 Canvas layer 64 Back cover rubber layer 69 Si
70 belt running test machine 71 driving rib pulley 72 driven rib pulley

Claims (11)

A rubber molded product having a rubber layer,
The rubber layer is
A polymer,
A filler dispersed in the polymer,
The rubber molding is characterized in that the filler is at least one of plasma-irradiated carbon black, clay and silica.   The rubber molded article according to claim 1, wherein the filler is dispersed in the polymer by kneading with the polymer in the presence of a supercritical fluid.   The rubber molded product according to claim 1, wherein the filler is irradiated with plasma at atmospheric pressure. A reinforcing layer bonded to the rubber layer;
The rubber molded product according to any one of claims 1 to 3, wherein the rubber molded product is molded as a transmission belt. A reinforcing layer bonded to the rubber layer;
The rubber molded product according to any one of claims 1 to 3, wherein the rubber molded product is molded as a conveyor belt. A step (a) of forming a plasma treatment filler by irradiating the filler with plasma;
And (b) a step of kneading the plasma-treated filler and a polymer.   The method for producing a rubber composition according to claim 6, wherein in the step (b), kneading is performed in the presence of a supercritical fluid.   The said supercritical fluid consists of a carbon dioxide or nitrogen, The manufacturing method of the rubber composition of Claim 7 characterized by the above-mentioned. The step (a)
Crushing agglomerates contained in the filler by charging the filler;
The method for producing a rubber composition according to any one of claims 6 to 8, further comprising a step of irradiating the filler with the agglomerates crushed.   The method for producing a rubber composition according to any one of claims 6 to 9, wherein the plasma irradiation is performed at atmospheric pressure.   The method for producing a rubber composition according to any one of claims 6 to 10, wherein the filler is at least one of carbon black, clay, and silica.

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