JP2004175103A - Producing method for rubber sheet containing short fiber - Google Patents

Producing method for rubber sheet containing short fiber Download PDF

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JP2004175103A
JP2004175103A JP2003283066A JP2003283066A JP2004175103A JP 2004175103 A JP2004175103 A JP 2004175103A JP 2003283066 A JP2003283066 A JP 2003283066A JP 2003283066 A JP2003283066 A JP 2003283066A JP 2004175103 A JP2004175103 A JP 2004175103A
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rubber
short fibers
die
molded body
rubber sheet
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Takayuki Tagawa
孝之 田川
Tomohiro Miwa
朋広 三輪
Toshihiro Nishimura
年弘 西村
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Mitsuboshi Belting Ltd
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Mitsuboshi Belting Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/365—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using pumps, e.g. piston pumps
    • B29C48/37—Gear pumps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/375—Plasticisers, homogenisers or feeders comprising two or more stages
    • B29C48/387—Plasticisers, homogenisers or feeders comprising two or more stages using a screw extruder and a gear pump

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a producing method for a rubber sheet containing short fibers which eliminates generation of a weld line, makes the amount of discharging of a tubular molded body large by reducing flow resistance and inner pressure, and has improved orientation of short fibers. <P>SOLUTION: The producing method for rubber sheet containing short fibers is as follows: after mixing and kneading rubbers and short fibers by an extrusion screw 4 of a cylinder 3, an inner die 7 is extruded by an annular expansion die 5 housed in an outer die 6 through a gear pump 30, and a tube shaped molded body 10 of rubber 15 containing short fibers is made and cut open into sheets. The inner die 7 has a conical shape where the diameter is gradually extended toward an outlet. The rubber 15 kneaded by the extrusion screw 4 is moved without flow inhibition and without changing a flow direction, and while passing through a rubber path 8 of the annular expansion die 5, it is molded by extrusion molding into a tube shaped molded body 10 where short fibers are oriented toward the circumference. The tube shaped molded body 10 is cut along the direction of extrusion, and is rolled up by a one-sheet 22. <P>COPYRIGHT: (C)2004,JPO

Description

本発明は短繊維入りゴムシートの製造方法に係り、詳しくは押出スクリューで混練した短繊維混入ゴムが流動阻害を受けず、かつ流れ方向を変えることなく移動し、そして吐出口へ向かって徐々に径を大きくした拡張ダイのゴム通路の中を通過しながら短繊維を円周方向へ配向させた筒状成形体に押出することで、ウェルドラインの発生をなくし、流動抵抗と内圧を減じて筒状成形体の吐出量を多くし、そして短繊維の配向性を向上させた短繊維入りゴムシートの製造方法に関する。   The present invention relates to a method for producing a rubber sheet containing short fibers, and in particular, short fiber-mixed rubber kneaded by an extrusion screw is not affected by flow inhibition, moves without changing the flow direction, and gradually moves toward the discharge port. The short fibers are extruded into a cylindrical body oriented in the circumferential direction while passing through the rubber passage of the expansion die with a large diameter, eliminating weld lines, reducing flow resistance and internal pressure, The present invention relates to a method for producing a rubber sheet containing short fibers in which the discharge amount of a shaped article is increased and the orientation of short fibers is improved.

従来から未加硫ゴム中に短繊維を一定方向へ配向させる方法としては、圧延シート作製工程において回転速度を変えた一対のカレンダーロールに短繊維を含んだ未加硫ゴムを投入し、圧延されたゴムシート中の短繊維をシートの圧延方向へ配向させ、そして成形するベルト幅に応じて切断していた。その後、積層工程においてカットした圧延シートを数枚重ね合わせて所定厚みに積層し、続いて巻付け工程において短繊維が幅方向に配向した積層物を成形ドラムに巻き付けて伝動ベルトの製造に使用していた。   Conventionally, as a method of orienting the short fibers in a certain direction in the unvulcanized rubber, the unvulcanized rubber containing the short fibers is put into a pair of calender rolls having different rotation speeds in a rolled sheet production step, and the rolled sheet is rolled The short fibers in the rubber sheet were oriented in the rolling direction of the sheet and cut according to the belt width to be formed. After that, several rolled sheets cut in the laminating step are stacked and laminated to a predetermined thickness, and then, in the winding step, the laminate in which short fibers are oriented in the width direction is wound around a forming drum and used for manufacturing a power transmission belt. I was

即ち、ＶリブドベルトやローエッジＶベルトの伝動ベルトの製造方法では、円筒状の成型ドラムの周面に１〜複数枚のカバー帆布と接着ゴム層とを巻き付けた後、この上にコードからなる心線を螺旋状にスピニングし、更に圧縮ゴム層を順次巻き付けて積層体を得た後、これを加硫してベルトスリーブにしていた。ここで使用する圧縮ゴム層は、３〜４枚重ね合わせた厚みのもので、シート幅方向に短繊維が配向したものを成型ドラムに巻き付けていた。   That is, in a method of manufacturing a V-ribbed belt or a low-edge V-belt transmission belt, one or more sheets of cover canvas and an adhesive rubber layer are wound around the peripheral surface of a cylindrical forming drum, and a cord made of a cord is placed thereon. Was spirally spun, and a compressed rubber layer was sequentially wound thereon to obtain a laminate, which was then vulcanized to form a belt sleeve. The compression rubber layer used here had a thickness of three to four sheets laminated together, and the short fibers oriented in the sheet width direction were wound around a molding drum.

しかし、圧延シートは、厚みを薄くしなければ、短繊維をシート圧延方向に充分に配向させることができないため、やむを得ずシートを重ねて所望の厚みとしていることから、ベルト成形用シートを得るには多大の工数を要していた。   However, if the rolled sheet is not thinned, the short fibers cannot be sufficiently oriented in the sheet rolling direction. It required a lot of man-hours.

これを改善する方法として、拡張ダイを取付けた押出機を用い、短繊維を押出円筒体の円周方向に配向させるもので、中間空間に、入口空間の所定の流路幅から出口空間の所定の流路幅まで流路幅が変化する拡大空間部を設け、拡張ダイの出口空間の断面積を入口空間の断面積より所定量大きく形成し、さらに入口部分の流路幅が中間部分の流路幅よりも狭く、出口部分の流路幅が中間部分の流路幅以下に設定したものが、提案された。しかも、上記拡張ダイは外ダイと内ダイとセンターブロックからなり、押出機に取付けたスパイダー軸に拡張ダイを機械的に固定した構造になっている。（例えば、特許文献１参照）   As a method of improving this, an extruder equipped with an expansion die is used, and the short fibers are oriented in the circumferential direction of the extrusion cylindrical body. An enlarged space portion in which the flow passage width changes up to the flow passage width is formed, the cross-sectional area of the outlet space of the expansion die is formed to be larger than the cross-sectional area of the inlet space by a predetermined amount, and the flow passage width of the inlet portion is the flow of the intermediate portion It has been proposed that the width of the outlet portion is smaller than the width of the intermediate portion and smaller than the width of the channel. In addition, the expansion die includes an outer die, an inner die, and a center block, and has a structure in which the expansion die is mechanically fixed to a spider shaft attached to an extruder. (For example, see Patent Document 1)

また、特許文献２には、拡張ダイから押出された円筒状の短繊維複合エラストマーを拡張ダイから押出した後、更に円周方向に徐々に伸張させる製造装置が提案されているが、ここでも押出機に取付けたスパイダー軸に内側ダイを機械的に固定した構造になっている。
特公平６−９８４７号公報 特公平６−８８３０３号公報 Further, Patent Document 2 proposes a manufacturing apparatus in which a cylindrical short fiber composite elastomer extruded from an expansion die is extruded from the expansion die and then gradually expanded in the circumferential direction. The inner die is mechanically fixed to the spider shaft attached to the machine.
Japanese Patent Publication No. 6-9847 Japanese Patent Publication No. 6-88303

しかしながら、従来の拡張ダイを使用する方法では、入口空間／中間空間、中間空間／出口空間の流路幅比率、入口部分／出口部分の半径、断面積の制御により３次元的に配向率の調整を行うものであるが、ダイ形状に起因する流れの力で配向率を制御しているため、ダイを交換しなければ配向率を変えることができなかった。   However, in the method using a conventional expansion die, the orientation ratio is three-dimensionally adjusted by controlling the flow path width ratio of the inlet space / intermediate space, the intermediate space / outlet space, the radius of the inlet / outlet portion, and the cross-sectional area. However, since the orientation ratio is controlled by the flow force caused by the shape of the die, the orientation ratio could not be changed unless the die was replaced.

しかも、上記拡張ダイは外ダイと内ダイとセンターブロックからなり、押出機に取付けたスパイダー軸にこれらの部材を機械的に固定した構造になっているため、ゴムの流れがスパイダー軸によって阻害され、内圧を減じて筒状成形体の吐出量を多することが困難であった。しかも、２つのゴム通路内の流動ゴムがダイの入口付近でスパイダー軸に巻き込んで当接し、この部分でウェルドラインが発生した。即ち、右回りと左回り方向へ塑性流動中の短繊維混入ゴムが衝突する領域あるいは流れ難い領域になり、短繊維がランダム配向して配向性も悪く、また厚みも他の領域に比べて薄くなり、品質的に不具合のある領域となっていた。   In addition, the expansion die is composed of an outer die, an inner die, and a center block, and has a structure in which these members are mechanically fixed to a spider shaft attached to the extruder, so that the flow of rubber is hindered by the spider shaft. In addition, it has been difficult to increase the discharge amount of the cylindrical molded body by reducing the internal pressure. Moreover, the flowing rubber in the two rubber passages was wound around the spider shaft near the entrance of the die and abutted, and a weld line was generated at this portion. That is, it becomes a region where the short fiber-mixed rubber plastically flows in the clockwise direction and the counterclockwise direction or a region where the rubber hardly flows, the short fibers are randomly oriented, the orientation is poor, and the thickness is thinner than other regions. In other words, the area was defective in quality.

また、シリンダーの先端に接続したダイによってゴムの流れを水平方向から直角方向へ変換したクロスヘッドの押出しでは、ダイ部は垂直方向に配置されるために撓み等の内部歪みが小さいため円筒押出成形品の厚み等の寸法精度が向上する。しかし、円筒押出成形品の円周方向の厚み分布を均一化させるためのクロスヘッド内のゴム流路設計（フローガイド）によって、通常、ウェルドラインが押出機側とこれと１８０°対角側の２個所から、押出機側から１８０°対角側の１個所で発生した。   In the case of crosshead extrusion, in which the rubber flow is changed from horizontal to right angle by a die connected to the end of the cylinder, the die is arranged vertically and the internal distortion such as bending is small, so cylindrical extrusion is performed. The dimensional accuracy such as the thickness of the product is improved. However, due to the rubber flow path design (flow guide) in the crosshead for uniformizing the circumferential thickness distribution of the cylindrical extruded product, the weld line is usually formed between the extruder side and the 180 ° diagonal side with the extruder side. From two locations, it occurred at one location 180 ° diagonal from the extruder side.

本発明はかかる問題に着目し、鋭意研究した結果、短繊維混入ゴムをシリンダー内で流動阻害させず、かつ流れ方向を変えることなく移動させ、吐出口へ向かって徐々に径を大きくした拡張ダイのゴム通路の中を通過させながら短繊維を円周方向へ配向させた筒状成形体に押出して、ウェルドラインの発生をなくし、流動抵抗と内圧を減じて筒状成形体の吐出量を多くし、そして短繊維の配向性を向上させた短繊維入りゴムシートの製造方法を提供することを目的とする。   The present invention pays attention to such a problem, and as a result of diligent research, it has been found that an expansion die in which short fiber-containing rubber is moved in a cylinder without obstructing its flow and changing its flow direction, and gradually increasing in diameter toward a discharge port. While passing through the rubber passage, the short fibers are extruded into a cylindrical molded body oriented in the circumferential direction, eliminating the occurrence of weld lines, reducing flow resistance and internal pressure, and increasing the discharge amount of the cylindrical molded body. An object of the present invention is to provide a method for producing a rubber sheet containing short fibers in which the orientation of short fibers is improved.

上記した目的を達成すべく本願請求項１記載の発明は、短繊維とゴムをシリンダーの押出スクリューで混練りした後、出口へ向かって徐々に径を拡張して円錐形にした内ダイを外ダイに収容した環状拡張ダイによって押出し、得られた短繊維入ゴムの筒状成形体を切開してシートに仕上げる短繊維入りゴムシートの製造方法において、
該押出スクリューで混練された短繊維混入ゴムが、流動阻害を受けず、かつ流れ方向を変えることなく移動し、環状拡張ダイのゴム通路の中を通過しながら短繊維を円周方向に配向させた筒状成形体に押出成形され、
上記筒状成形体を押出方向に沿って切断しながら一枚のゴムシートに巻き取る、短繊維入りゴムシートの製造方法にある。 In order to achieve the above-mentioned object, the invention according to claim 1 of the present application comprises kneading short fibers and rubber with an extrusion screw of a cylinder, and then gradually expanding the diameter toward an outlet to form a conical inner die. Extrusion by an annular expansion die housed in a die, in a method for producing a short fiber-containing rubber sheet, in which the obtained short fiber-containing rubber cylindrical molded body is cut out and finished into a sheet,
The short fiber-mixed rubber kneaded by the extrusion screw moves without being affected by flow inhibition and without changing the flow direction, and orients the short fibers in the circumferential direction while passing through the rubber passage of the annular expansion die. Extruded into a cylindrical molded body
A method for producing a short-fiber-containing rubber sheet, wherein the above-mentioned cylindrical molded body is wound along a single rubber sheet while being cut along the extrusion direction.

この製造方法では、押出スクリューで混練した短繊維混入ゴムがシリンダー内で流動阻害を受けずに、かつ流れ方向を変えることなく移動するために、筒状成形体にはウェルドラインが発生せず、またシリンダー内の内圧を高めて筒状成形体の吐出量を多くし、そして短繊維の配向を向上させることができる。   In this production method, the short fiber-mixed rubber kneaded by the extrusion screw moves in the cylinder without flow inhibition and without changing the flow direction, so that no weld line is generated in the cylindrical molded body, Further, the internal pressure in the cylinder can be increased to increase the discharge amount of the cylindrical molded body, and the orientation of the short fibers can be improved.

本願請求項２記載の発明は、押出スクリューと内ダイ間のゴム通路が、短繊維混入ゴムのみが存在する空間を形成している短繊維入りゴムシートの製造方法にあり、該ゴム通路の容積が広くなって短繊維混入ゴムがシリンダー内を流動し易くなっている。   The invention according to claim 2 of the present application resides in a method for producing a rubber sheet containing short fibers, in which a rubber passage between an extrusion screw and an inner die forms a space in which only short-fiber-mixed rubber is present. And the rubber mixed with short fibers easily flows in the cylinder.

本願請求項３記載の発明は、押出スクリューで混練された短繊維混入ゴムは、ギアポンプを通した後、拡張ダイに案内される短繊維入りゴムシートの製造方法にあり、大量の短繊維混入ゴムを低圧力で拡張ダイへ送り込んで、内部発熱の少ない短繊維配向ゴムシートにすることができる。   The invention according to claim 3 of the present application resides in a method for producing a rubber sheet containing short fibers, wherein the rubber mixed with short fibers kneaded by an extrusion screw is guided by an expansion die after passing through a gear pump. Is fed to the expansion die at low pressure to obtain a short fiber oriented rubber sheet with little internal heat generation.

本願請求項に係る発明では、押出スクリューで混練した短繊維混入ゴムがシリンダー内で流動阻害を受けず、かつ流れ方向を変えることなく移動し、そして環境拡張ダイのゴム通路の中を通過させながら短繊維を円周方向に配向させた筒状成形体を押出成形し、筒状成形体を押出方向に沿って切断除去しながら一枚のゴムシートに巻き取る短繊維入りゴムシートの製造方法にあり、筒状成形体にはウェルドラインの発生をなくし、流動抵抗と内圧を減じて筒状成形体の吐出量を多くし、そして短繊維の配向性を向上させることができる。また多量の短繊維混入ゴムを低圧力で拡張ダイに送り込むことで、内部発熱が少ないゴムシートが得られるとともに、押出スクリューの長さを短縮して装置を小型化できるといった効果もある。   In the invention according to the present invention, the short fiber-mixed rubber kneaded by the extrusion screw is not hindered from flowing in the cylinder, moves without changing the flow direction, and passes through the rubber passage of the environmental expansion die. A method for producing a rubber sheet containing short fibers, in which a cylindrical molded body in which short fibers are circumferentially oriented is extruded, and the cylindrical molded body is cut and removed along the extrusion direction and wound on a single rubber sheet. In addition, it is possible to eliminate the occurrence of weld lines in the cylindrical molded body, reduce the flow resistance and the internal pressure, increase the discharge amount of the cylindrical molded body, and improve the orientation of short fibers. In addition, by feeding a large amount of rubber mixed with short fibers to the expansion die at a low pressure, a rubber sheet with less internal heat generation can be obtained, and the length of the extrusion screw can be shortened to reduce the size of the apparatus.

以下、添付図面を参照し、本発明の実施例を説明する。   Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

図１は本発明に係る短繊維入りゴムシートの製造方法に使用する押出装置の概略図であり、図２は押出成形された円筒状成形体を直線状に切開しながら短繊維入りゴムシートにする状態の概略図である。本短繊維入りゴムシートの製造方法に用いる押出装置１では、シリンダー３内の押出スクリュー４の回転により短繊維含有ゴムを混練する押出機２と、外ダイ６と円錐形状の内ダイ７を組合せて出口へ向かって徐々に径を拡張してゴム通路８を有する環状拡張ダイ５と、押出された直後の筒状成形体１０の頂部を切断してゴムシートにする切断手段１２とから構成されている。   FIG. 1 is a schematic view of an extruder used in the method for producing a rubber sheet containing short fibers according to the present invention, and FIG. 2 is a diagram illustrating a method for forming a rubber sheet containing short fibers while linearly cutting an extruded cylindrical molded body. FIG. In the extruder 1 used in the method for producing a rubber sheet containing short fibers, an extruder 2 for kneading short fiber-containing rubber by rotation of an extrusion screw 4 in a cylinder 3, an outer die 6 and a conical inner die 7 are combined. An annular expansion die 5 having a rubber passage 8 whose diameter is gradually expanded toward the outlet, and cutting means 12 for cutting the top of the cylindrical molded body 10 immediately after being extruded into a rubber sheet. ing.

上記押出機２のシリンダー３内には、回転可能に押出スクリュー４が収容され、原料投入口から入れて短繊維を含むゴム配合物を押出スクリュー４の回転により混練して短繊維混入ゴム１５にする。この時にシリンダー３内の空気やゴム配合物から発生したガス等は排気口（図示せず）から排出される。シリンダー３の温度はゴム種に応じて変更するが、通常４０〜１００°Ｃに調節され、短繊維とゴムは混練されやすい温度に加熱されて熱可塑化し、押出成形しやすい状態になる。また、この場合の混練時間はゴムの加硫が進行しない程度に調節する。   An extruder screw 4 is rotatably accommodated in the cylinder 3 of the extruder 2. The extruder 2 is inserted through a raw material inlet, and a rubber compound containing short fibers is kneaded by the rotation of the extruder screw 4 to form a short fiber mixed rubber 15. I do. At this time, the air and the gas generated from the rubber compound in the cylinder 3 are discharged from an exhaust port (not shown). The temperature of the cylinder 3 varies depending on the type of rubber, but is usually adjusted to 40 to 100 ° C., and the short fibers and rubber are heated to a temperature at which they can be easily kneaded, are thermoplasticized, and are ready to be extruded. Further, the kneading time in this case is adjusted to such an extent that the vulcanization of the rubber does not proceed.

環状拡張ダイ５は、円錐形の内ダイ７と外ダイ６を組合せて、これらのダイ６、７の間に所定間隙のゴム通路８を設けている。短繊維混入ゴム１５は吐出口９へ向かって徐々に大きくなる円周方向への引き伸ばしを受けながら短繊維を円周方向に配向させた筒状成形体１０に押出成形する。   The annular expansion die 5 combines a conical inner die 7 and an outer die 6 and provides a rubber passage 8 with a predetermined gap between these dies 6, 7. The short fiber mixed rubber 15 is extruded into a cylindrical molded body 10 in which the short fibers are oriented in the circumferential direction while being stretched in the circumferential direction that gradually increases toward the discharge port 9.

内ダイ７は押出装置１の外側に配置された支持部材１７に機械的に固定され、内ダイ７と押出スクリュー４間のゴム通路１８は短繊維混入ゴムのみが存在する空間になり、また内ダイ７と押出スクリュー４の先端部とは、相対向した位置にあって同一の中心軸線上に配置されている。このため、押出スクリュー４によって混練された短繊維混入ゴム１５はゴム通路１８内で流動阻害を受けず、かつ流れ方向を変えることなくスムーズに移動し、そして環状拡張ダイ５のゴム通路８の中を通過しながら短繊維を円周方向に配向させた筒状成形体１０に押出成形する。   The inner die 7 is mechanically fixed to a support member 17 arranged outside the extruder 1, and the rubber passage 18 between the inner die 7 and the extrusion screw 4 is a space in which only the short fiber-mixed rubber exists. The die 7 and the tip end of the extrusion screw 4 are located at positions facing each other and on the same central axis. For this reason, the short fiber mixed rubber 15 kneaded by the extrusion screw 4 does not suffer from flow inhibition in the rubber passage 18, moves smoothly without changing the flow direction, and moves inside the rubber passage 8 of the annular expansion die 5. Is extruded into a cylindrical molded body 10 in which the short fibers are circumferentially oriented.

内ダイ７と外ダイ６の流路幅（ニップル）は、入口から吐出口９付近まで均一にして短繊維混入ゴム１５をブレーキをかけることなくスムーズに押圧し、そして吐出口９付近で小さくして、内部歪みのない均一な厚みの筒状成形体１０に仕上げる。   The flow path width (nipple) of the inner die 7 and the outer die 6 is made uniform from the inlet to the vicinity of the discharge port 9 to smoothly press the short fiber mixed rubber 15 without applying a brake, and to reduce the width near the discharge port 9. Thus, the cylindrical molded body 10 having a uniform thickness without internal distortion is finished.

内ダイ７の形状は、先端部２０から吐出口９へ向かって徐々に径が拡張し、そのテーパー角度θが３０°≦θ≦８０°である。ゴム流路入口径が２０〜１２０ｍｍ、ゴム流路出口径が１００〜４４０ｍｍ、そしてその比率である拡張比（ゴム流路出口径／ゴム流路入口径）が１．５〜１２．５に設定される。この設定範囲未満であれば、内ダイ７の吐出口９付近での円周方向への引き伸ばしが小さくて、厚みの大きな筒状成形体１０の内外層では短繊維が円周方向に配向しにくくなり、一方この設定範囲を越えると、円周方向への引き伸ばしが大きくなり過ぎて、押出圧力が劣る場合には、筒状成形体１０が裂けやすい。   The shape of the inner die 7 gradually increases in diameter from the distal end portion 20 toward the discharge port 9, and the taper angle θ is 30 ° ≦ θ ≦ 80 °. The rubber channel inlet diameter is 20 to 120 mm, the rubber channel outlet diameter is 100 to 440 mm, and the expansion ratio (rubber channel outlet diameter / rubber channel inlet diameter) is set to 1.5 to 12.5. Is done. If it is less than the set range, the circumferential stretching near the discharge port 9 of the inner die 7 is small, and the short fibers are less likely to be circumferentially oriented in the inner and outer layers of the thick cylindrical molded body 10. On the other hand, if the setting range is exceeded, the stretching in the circumferential direction becomes too large, and if the extrusion pressure is inferior, the tubular molded body 10 is easily torn.

切断手段１２は、カッター、ナイフといった刃物、あるいはレーザーナイフ、超音波振動付きカッターからなり、筒状成形体１２を引裂くように切断し、１枚の所定幅を有するシート２２に仕上げる。（図２参照）無論、刃物のような切断手段１２を加熱保温すれば、筒状成形体１０の切開を容易にすることもできる。切断された１枚のシート２２は個別にガイドロールを経由し、ライナーとともに巻取ロール（図示せず）に巻付けられる。   The cutting means 12 includes a cutter such as a cutter or a knife, or a laser knife or a cutter with ultrasonic vibration. The cutting means 12 cuts the tubular molded body 12 so as to tear it, and finishes the sheet 22 having one predetermined width. (See FIG. 2) Needless to say, if the cutting means 12 such as a blade is heated and kept warm, the cutting of the cylindrical molded body 10 can be facilitated. One cut sheet 22 is individually wound around a winding roll (not shown) together with a liner via a guide roll.

ここで使用するゴムとしては、天然ゴム、ブチルゴム、スチレン−ブタジエンゴム、クロロプレンゴム、エチレン−プロピレンゴム、アルキル化クロロスルファン化ポリエチレン、水素化ニトリルゴム、水素化ニトリルゴムと不飽和カルボン酸金属塩との混合ポリマー、エチレン−プロピレンゴム（ＥＰＲ）やエチレン−プロピレン−ジエンモノマー（ＥＰＤＭ）からなるエチレン−α−オレフィンエラストマー等のゴム材の単独、またはこれらの混合物が使用される。ジエンモノマーの例としては、ジシクロペンタジエン、メチレンノルボルネン、エチリデンノルボルネン、１，４−ヘキサジエン、シクロオクタジエンなどが挙げることができる。   Examples of the rubber used here include natural rubber, butyl rubber, styrene-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, alkylated chlorosulfanated polyethylene, hydrogenated nitrile rubber, hydrogenated nitrile rubber, and unsaturated carboxylic acid metal salt. And a rubber material such as an ethylene-α-olefin elastomer composed of ethylene-propylene rubber (EPR) or ethylene-propylene-diene monomer (EPDM) alone, or a mixture thereof. Examples of the diene monomer include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene, and the like.

上記ゴムには、アラミド繊維、ポリアミド繊維、ポリエステル繊維、綿等の繊維からなり繊維の長さは繊維の種類によって異なるが、１〜１０ｍｍ程度の短繊維が用いられ、例えばアラミド繊維であると３〜５ｍｍ程度、ポリアミド繊維、ポリエステル繊維、綿であると５〜１０ｍｍ程度のものが用いられる。その添加量はゴム１００重量部に対して１０〜４０重量部である。   The rubber is made of fibers such as aramid fiber, polyamide fiber, polyester fiber, and cotton, and the length of the fiber varies depending on the type of the fiber. Short fibers of about 1 to 10 mm are used. Polyamide fiber, polyester fiber, and cotton having a size of about 5 to 10 mm are used. The addition amount is 10 to 40 parts by weight based on 100 parts by weight of the rubber.

更に、本発明のゴムには、軟化剤、カーボンブラックからなる補強剤、充填剤、老化防止剤、加硫促進剤、加硫剤等が添加される。   Further, a softener, a reinforcing agent composed of carbon black, a filler, an antioxidant, a vulcanization accelerator, a vulcanizing agent and the like are added to the rubber of the present invention.

上記軟化剤としては、一般的なゴム用の可塑剤、例えばジブチルフタレート（ＤＢＰ）、ジオクチルフタレート（ＤＯＰ）等のフタレート系、ジオクチルアジペート（ＤＯＡ）等のアジペート系、ジオクチルセバケート（ＤＯＳ）等のセバケート系、トリクレジルホスフェート等のホスフェートなど、あるいは一般的な石油系の軟化剤が含まれる。   Examples of the softener include plasticizers for general rubbers, for example, phthalates such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP), adipates such as dioctyl adipate (DOA), and dioctyl sebacate (DOS). It includes sebacate-based phosphates such as tricresyl phosphate, and general petroleum-based softeners.

しかして、本発明の短繊維入りゴムシートの製造方法では、予めゴムに少なくとも短繊維をオープンロール、混練機などによって荒練してマスターバッチを作製することができる。この方法では、オープンロールによってポリマー１００重量部に１０〜４０重量部の短繊維を投入して混練した後、混練したマスターバッチをいったん放出し、これを２０〜５０°Ｃまで冷却する。これはゴムのスコーチを防止するためである。   According to the method for producing a rubber sheet containing short fibers of the present invention, a master batch can be prepared by roughly kneading at least short fibers in rubber with an open roll, a kneader or the like. In this method, 10 to 40 parts by weight of short fibers are added to 100 parts by weight of a polymer by an open roll and kneaded, and then the kneaded master batch is discharged once and cooled to 20 to 50 ° C. This is to prevent rubber scorch.

尚、短繊維とともに１〜１０重量部の軟化剤を投入することができる。これによって短繊維とゴムのなじみが良くなり、ゴム中への分散が良くなるばかりか、短繊維自体が絡み合って綿状になるのを防ぐ効果がある。即ち、軟化剤が短繊維に浸透し、素繊維同士の絡み合いがほぐれるための潤滑剤としての役割をはたし、短繊維が綿状になるのを阻止し、かつ短繊維とゴムのなじみが良くなって短繊維の分散が良くなる   In addition, 1 to 10 parts by weight of a softening agent can be added together with the short fibers. This improves the familiarity between the short fibers and the rubber and improves the dispersion in the rubber, and also has the effect of preventing the short fibers themselves from becoming entangled and becoming flocculent. In other words, the softener penetrates into the short fibers and acts as a lubricant to loosen the entanglement between the elementary fibers, prevents the short fibers from becoming cotton-like, and reduces the familiarity between the short fibers and the rubber. Better short fiber dispersion

続いて、シリンダー３の押出スクリュー４で混練りした後、短繊維混入ゴム１５をシリンダー４と相対向した位置にあって同一の中心軸線上に配置した内ダイ７間のゴム通路１８で流動阻害を受けず、かつ流れ方向を変えることなくスムーズに環境拡張ダイ５のゴム通路８へ流し、そして該ゴム通路８の中を通過させながら短繊維を円周方向に配向させた筒状成形体１０に押出成形する。このため、ゴム通路１８には、スパイダーのような阻害物がなく、筒状成形体にはウェルドラインの発生がなく、かつシリンダーの内圧を減じて筒状成形体の吐出量を多くし、短繊維の配向性を向上させることができる。   Subsequently, after kneading with the extrusion screw 4 of the cylinder 3, the short fiber-containing rubber 15 is flow-inhibited by the rubber passage 18 between the inner dies 7 located at the position facing the cylinder 4 and on the same central axis. Cylindrical molded body 10 which flows smoothly into the rubber passage 8 of the environment expansion die 5 without changing the flow direction, and in which the short fibers are circumferentially oriented while passing through the rubber passage 8. Extrusion molding. For this reason, there is no obstacle such as a spider in the rubber passage 18, no weld line is generated in the cylindrical molded body, and the internal pressure of the cylinder is reduced to increase the discharge amount of the cylindrical molded body. Fiber orientation can be improved.

その後、連続して押出成形された筒状成形体１０は、図２に示すように短繊維が内層から外層にかけて円周方向に均一に配向した厚さ１〜１０ｍｍのものであり、切断手段１２によって１個所切開しながら一枚のゴムシート２２にし、該ゴムシート２２を巻き取る。これを次工程の成型ドラムの周面に巻付けて伝動ベルトの成形に使用することができる。   Thereafter, the cylindrical molded body 10 continuously extruded has a thickness of 1 to 10 mm in which short fibers are uniformly oriented in the circumferential direction from the inner layer to the outer layer as shown in FIG. Is cut into one rubber sheet 22 to make one rubber sheet 22, and the rubber sheet 22 is wound up. This can be wound around the peripheral surface of the forming drum in the next step and used for forming the power transmission belt.

図３に示す装置１では、シリンダー３と拡張ダイ５の間にギアポンプ３０が介在し、押出機２においてシリンダー３内の押出スクリュー４の回転により混練された短繊維混入ゴムは、噛み合い回転する駆動ギア３１と従動ギア３２の間を通って、強制的に拡張ダイ５に送り込まれて筒状成形体として押出された後、切断手段１２によって筒状成形体１０の頂部を切断してゴムシートにするよう構成されている。   In the apparatus 1 shown in FIG. 3, a gear pump 30 is interposed between the cylinder 3 and the expansion die 5, and the short fiber mixed rubber kneaded by the rotation of the extrusion screw 4 in the cylinder 3 in the extruder 2 is driven by meshing rotation. After passing between the gear 31 and the driven gear 32 and forcibly fed into the expansion die 5 and extruded as a cylindrical molded body, the cutting unit 12 cuts the top of the cylindrical molded body 10 to form a rubber sheet. It is configured to be.

ギアポンプ３０を利用することにより、押出し安定までの時間が短くなり、歩留まりが向上するといった利点がある。またヘッド圧力の変化によらず一定の押出し量が確保できるため、押出物、すなわち筒状成形体１０の温度を低く保つことができ、得られた筒状成形体１０の寸法のバラツキが少ないといった効果もある。さらに押出スクリュー４（シリンダー３）の長さを短縮することが可能で、装置１を小型化することができる。   The use of the gear pump 30 has the advantages of shortening the time until the extrusion is stabilized and improving the yield. In addition, since a constant amount of extrusion can be ensured irrespective of a change in the head pressure, the temperature of the extrudate, that is, the temperature of the cylindrical molded body 10 can be kept low, and the dimensional variation of the obtained cylindrical molded body 10 is small. There is also an effect. Further, the length of the extrusion screw 4 (cylinder 3) can be reduced, and the size of the apparatus 1 can be reduced.

得られた短繊維入りゴムシートは、Ｖリブドベルト、ダブルＶリブドベルト、ローエッジＶベルト等の伝動ベルトに適用できる。   The obtained rubber sheet containing short fibers can be applied to transmission belts such as a V-ribbed belt, a double V-ribbed belt, and a low-edge V-belt.

本発明に係る短繊維入りゴムシートの製造方法に使用する押出装置の概略図である。It is the schematic of the extrusion apparatus used for the manufacturing method of the rubber sheet containing short fibers which concerns on this invention. 押出成形された円筒状成形体を直線状に切開しながら短繊維入りゴムシートにする状態の概略図である。FIG. 3 is a schematic view showing a state in which the extruded cylindrical molded body is cut straight into a rubber sheet containing short fibers. 本発明に係る短繊維入りゴムシートの製造方法に使用する別の押出装置の概略図である。It is the schematic of another extrusion apparatus used for the manufacturing method of the rubber sheet containing short fibers which concerns on this invention.

符号の説明Explanation of reference numerals

１ 押出装置
２ 押出機
３ シリンダー
４ 押出スクリュー
５ 環状拡張ダイ
６ 外ダイ
７ 内ダイ
８ ゴム通路
１０ 筒状成形体
１２ 切断手段
１５ 短繊維混入ゴム
１８ ゴム通路
２２ ゴムシート
３０ ギアポンプ
DESCRIPTION OF SYMBOLS 1 Extruder 2 Extruder 3 Cylinder 4 Extrusion screw 5 Annular expanding die 6 Outer die 7 Inner die 8 Rubber passage 10 Cylindrical molded body 12 Cutting means 15 Short fiber mixed rubber 18 Rubber passage 22 Rubber sheet 30 Gear pump

Claims (3)

短繊維とゴムをシリンダーの押出スクリューで混練りした後、出口へ向かって徐々に径を拡張して円錐形にした内ダイを外ダイに収容した環状拡張ダイによって押出し、得られた短繊維入りゴムの筒状成形体を切開してシートに仕上げる短繊維入りゴムシートの製造方法において、
該押出スクリューで混練された短繊維混入りゴムが、流動阻害を受けず、かつ流れ方向を変えることなく移動し、環状拡張ダイのゴム通路の中を通過しながら短繊維を円周方向に配向させた筒状成形体に押出成形され、
上記筒状成形体を押出方向に沿って切断しながら一枚のゴムシートに巻き取る、
ことを特徴とする短繊維入りゴムシートの製造方法。 After kneading the short fiber and rubber with the extrusion screw of the cylinder, the diameter is gradually expanded toward the outlet and the conical inner die is extruded by the annular expansion die housed in the outer die, and the obtained short fiber is contained. In a method for producing a rubber sheet containing short fibers, in which a rubber cylindrical molded body is cut out and finished into a sheet,
The short fiber mixed rubber kneaded by the extrusion screw moves without being obstructed by flow and without changing the flow direction, and orients the short fibers in the circumferential direction while passing through the rubber passage of the annular expansion die. Extruded into a cylindrical molded body,
Winding the above-mentioned tubular molded body into one rubber sheet while cutting along the extrusion direction,
A method for producing a rubber sheet containing short fibers. 押出スクリューと内ダイ間のゴム通路は、短繊維混入ゴムのみが存在する空間を形成している請求項１記載の短繊維入りゴムシートの製造方法。   The method for producing a rubber sheet containing short fibers according to claim 1, wherein the rubber passage between the extrusion screw and the inner die forms a space in which only the rubber mixed with short fibers is present. 押出スクリューで混練された短繊維混入ゴムは、ギアポンプを通した後、拡張ダイに案内される請求項１又は２記載の短繊維入りゴムシートの製造方法。
3. The method for producing a rubber sheet containing short fibers according to claim 1, wherein the short fiber-mixed rubber kneaded by the extrusion screw is guided to an expansion die after passing through a gear pump.
JP2003283066A 2002-11-14 2003-07-30 Producing method for rubber sheet containing short fiber Pending JP2004175103A (en)

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