JP2019119050A - Continuous kneading single screw extruder and method for producing rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous kneading single-screw extruder capable of producing a rubber composition having excellent dispersibility of a compounding agent, and a method for producing a rubber composition using the continuous kneading single-screw extruder. A continuous kneading single-screw extruder for kneading a rubber composition, comprising a screw, a cylinder arranged on the outer peripheral side of the screw, and a supply unit to which at least a rubber component is supplied, and a screw. Includes a screw shaft and a plurality of elements inserted into the screw shaft, the elements include at least a first element constituting a transport portion, a second element constituting a kneading portion, and a third element constituting a retention portion. The third element has an element, and the spiral blade is formed so as to return the rubber composition to the upstream side in the screw axial direction, and a retention portion is arranged on the downstream side in the screw axial direction of the kneading portion. A continuous kneading single-screw extruder characterized by this. [Selection diagram] Fig. 1

Description

  The present invention relates to a continuous kneading single-screw extruder for kneading a rubber composition and a method for producing a rubber composition using the continuous kneading single-screw extruder.

  The rubber composition is a raw material of vulcanized rubber constituting a tire or the like, and contains a rubber component, silica, carbon black, a silane coupling agent, an oil, and a compounding agent such as a vulcanizing agent. The rubber composition is manufactured by kneading these materials, and the batch type using a Banbury mixer etc. has been mainstream for the kneading, but in recent years the continuous type by the single axis or twin axis continuous kneading extruder is also It has been.

  Patent Document 1 below describes a technique for preventing excessive stagnation of an object to be kneaded in a cylinder by using a twin-screw extruder and devising an element constituting a screw.

Japanese Patent Application Publication No. 2003-245534

  However, as a result of intensive investigations by the present inventors, in the twin-screw extruder, the object to be kneaded is subjected to kneading while applying shear force to the object to be kneaded by the tip clearance formed between the cylinder wall and the screw. When the viscosity is high, or when the filling rate of the material to be kneaded in the cylinder is increased, the torque may be exceeded and it may not be possible to knead.

The present invention has been made in view of the above situation, and an object thereof is to use a continuous kneading single-screw extruder capable of producing a rubber composition excellent in the dispersibility of the compounding agent and the continuous kneading single-screw extruder. It is an object of the present invention to provide a method for producing a rubber composition.

  The above object can be achieved by the present invention as described below. That is, the present invention is a continuous kneading single-screw extruder for kneading a rubber composition, comprising: a screw, a cylinder disposed on the outer peripheral side of the screw, and a supply unit to which at least a rubber component is supplied. The screw includes a screw shaft and a plurality of elements inserted into the screw shaft, and the elements include at least a first element constituting a conveyance unit, a second element constituting a kneading unit, and a retention unit It has three elements, and the third element is formed such that the helical blade is in the direction to return the rubber composition to the upstream side in the screw axial direction, and the retention portion is disposed on the downstream side in the axial direction of the screw The present invention relates to a continuous kneading single screw extruder characterized in that

  The continuous kneading single-screw extruder according to the present invention comprises a screw having a screw shaft and a plurality of elements inserted into the screw shaft, and the elements at least comprise a first element constituting a conveying unit, and a kneading unit. It has the 2nd element which comprises, and the 3rd element which constitutes a retention part. Among these elements, the third element is formed such that the spiral blade is in the direction of returning the rubber composition to the upstream side in the screw axial direction, and the rubber composition is retained in the retention portion.

  By the way, in the continuous kneading single-screw extruder, the rubber composition is advanced from the upstream side to the downstream side while being kneaded, but in order to impart sufficient shear force to the rubber composition and knead so as to enhance the dispersibility of the compounding agent. In order to achieve this, it is necessary to increase the filling rate of the rubber composition in the kneading section and to apply a sufficient shearing force to the rubber composition. However, in the conventional continuous kneading single-screw extruder, when the rubber composition reaches the kneading section, the rubber composition generates heat due to the application of a shear force, and the flow rate increases with the decrease in viscosity, and the inside of the kneading section The filling factor of the rubber composition at As a result, sufficient shearing force may not be applied to the rubber composition in the kneading section, and the dispersibility of the compounding agent in the rubber composition may be reduced. When a twin-screw extruder was used, it was difficult to increase the filling rate of the rubber composition in the kneading section with concern about torque over, and it was difficult to improve the dispersibility of the compounding agent in the rubber composition. .

  However, in the continuous kneading single-screw extruder according to the present invention, the retention portion is constituted by the third element in which the spiral blade is formed so as to return the rubber composition upstream in the screw axial direction. The retention portion is disposed on the downstream side in the screw axial direction. As a result, it is possible to suppress an increase in the flow velocity of the rubber composition in the kneading section, maintain a high filling ratio of the rubber composition in the kneading section, and apply a sufficient shearing force to the rubber composition. As a result, when the continuous kneading single-screw extruder according to the present invention is used, a rubber composition having excellent dispersibility of the compounding agent can be produced.

  In the continuous kneading single-screw extruder, when the axial length of the retaining portion is A and the axial length of the kneading portion is B, it is preferable that 0.065 ≦ A / B ≦ 2. According to this configuration, the amount of the rubber composition present in the retention part is sufficiently ensured with respect to the rubber composition present in the kneading part, so the function of blocking the rubber composition in the kneading part is sufficiently exerted. It can. Thereby, the filling rate of the rubber composition in the kneading section can be maintained more suitably. As a result, it is possible to produce a rubber composition more excellent in the dispersibility of the compounding agent.

  In the above continuous kneading single-screw extruder, the rubber composition preferably contains silica, and the rubber composition contains 60 parts by mass or more of silica when the total amount of the rubber component is 100 parts by mass. It is more preferable that When the rubber composition contains silica, and further contains a predetermined amount or more of silica, the rubber composition has high viscosity, and when the filling rate of the rubber composition is increased in the kneading section, particularly in the case of a twin-screw extruder , Over torque and may become uncontrollable. However, with the above continuous kneading single-screw extruder, it is possible to produce a rubber composition excellent in the dispersibility of the compounding agent, particularly the dispersibility of the silica, while preventing the occurrence of torque over.

  The method for producing a rubber composition according to the present invention is characterized by producing by using and kneading the continuous kneading single-screw extruder described in any of the above. As described above, when the continuous kneading single-screw extruder according to the present invention is used, a rubber composition excellent in the dispersibility of the compounding agent can be produced in a continuous manner.

A conceptual diagram showing a continuous kneading single-screw extruder according to an embodiment of the present invention

  FIG. 1 is a conceptual view showing a continuous kneading single-screw extruder according to an embodiment of the present invention. The continuous kneading single-screw extruder 1 includes a screw 4, a cylinder 3 disposed on the outer peripheral side of the screw 4, and a supply unit 2 to which at least a rubber component is supplied. The screw 4 is connected to, for example, a drive device and is configured to be rotatable in the cylinder 3. The screw 4 may be configured to be able to move back and forth in the axial direction of the screw for the purpose of distributing the rubber composition during kneading in the cylinder 3. The cylinder 3 has a cylindrical inner surface on the outer peripheral side of the screw 4 and is designed to be able to apply a shearing force to the rubber composition with the screw 4. The inner surface of the cylinder may be provided with a shear pin projecting to the screw side, and designed to increase the shear force applied when kneading the rubber composition.

Usually, one or more openings are formed in the cylinder 3. In the present embodiment, an example is shown in which one opening is formed on the upstream side, and the supply unit 2 is disposed above the opening. Two or more openings may be formed, and two or more supply units may be disposed. The supply part 2 may have an arbitrary shape, and is designed to be able to supply a rubber component, other compounding agents, and the like by a method known to those skilled in the art such as a belt type, screw type or vibration type. The rubber component and the like can be supplied by methods known to those skilled in the art, and can be supplied into the cylinder, for example, in the form of pellets, sheets, strands, ribbons or other forms.

  The screw 4 provided in the continuous-kneading single-screw extruder includes a screw including a screw shaft and a plurality of elements inserted into the screw shaft, and the element includes at least a first element constituting the transport unit 5, a kneading unit A second element constituting 6 and a third element constituting the retention portion 7 are provided. The continuous kneading single-screw extruder according to the present invention has, for example, a plasticizing part intended for plasticizing a rubber component, and a rubber composition, as long as it has at least a conveying part, a kneading part, and a retaining part. It may have a cooling unit for the purpose of cooling. In addition, the retention portion may be disposed on the downstream side of the kneading portion in the axial direction of the screw. For example, the kneading portion and the retention portion may be disposed at two positions.

  The transport unit 5 is constituted by a first element, and the first element is provided with a spiral wing formed such that the top is continuously formed and the rubber composition is sent in the axial direction of the screw downstream. On the other hand, the kneading part 6 is comprised by the 2nd element, and the 2nd element is provided with the spiral blade by which the notch part was formed in multiple places in the circumferential direction.

  The retention portion 7 is constituted by a third element, and the third element is formed such that the spiral blade returns the rubber composition to the upstream side in the axial direction of the screw. That is, the spiral wing faces in the opposite direction to the first element constituting the transport unit 5, and plays a role of returning the rubber composition to the upstream side.

  The continuous kneading single-screw extruder according to the present invention is characterized in that the retaining portion 7 is disposed on the downstream side in the screw axial direction of the kneading portion 6 as a screw configuration. In particular, when the axial length of the retaining portion in the screw axial direction is A, and the axial length of the kneading portion in the screw axial direction is B, 0.065 ≦ A / B ≦ 2 with respect to the rubber composition present in the kneading portion, Since the amount of the rubber composition present in the retention portion is sufficiently ensured, the function of blocking the rubber composition in the kneading portion 6 can be sufficiently exhibited, which is preferable.

  In the present embodiment, the transport unit 5 is further disposed downstream of the retaining unit 7 in the screw axial direction, and finally, a die (not shown) is disposed downstream of the transport unit 5 in the screw axial direction. Alternatively, it can be connected with another extruder.

  By using the continuous kneading single-screw extruder according to the present invention, a rubber composition excellent in the dispersibility of the compounding agent can be produced. Such a continuous kneading single-screw extruder can be used either in the step of kneading the rubber component and the compounding agent other than the vulcanizing agent (non-pro kneading step) or in the step of kneading further with the vulcanizing agent (final kneading step) It is.

  Below, the compounding agent which comprises a rubber composition in this invention is demonstrated.

  A diene rubber can be suitably used as the rubber component. Examples of diene rubbers include natural rubber (NR), polyisoprene rubber (IR), styrene butadiene rubber (SBR), polybutadiene rubber (BR), and butadiene rubber (SPB) containing syndiotactic-1,2-polybutadiene, Chloroprene rubber (CR), nitrile rubber (NBR) and the like can be mentioned, and these can be used alone or as a blend of two or more. As these diene rubbers, those modified at the terminal (for example, terminal modified BR, terminal modified SBR, etc.), or those modified to give desired characteristics (for example, modified), as necessary NR) can also be used. As the terminal modified diene rubber, diene rubbers in which the polymer terminal is modified with various modifiers can be used, and various modification methods can be used.

  In addition to the rubber component, fillers usually used in the rubber industry can be blended, such as silica, carbon black, clay, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide and the like. Among the above-mentioned inorganic fillers, silica and carbon black can be particularly suitably used.

  As the silica, wet silica, dry silica, sol-gel silica, surface treated silica and the like used for usual rubber reinforcement are used. When the rubber composition contains silica, the viscosity of the rubber composition tends to be high, so it can be suitably used for the method for producing a rubber composition using the continuous kneading single-screw extruder according to the present invention. is there. In particular, the blending amount of silica is preferably 60 parts by mass or more, more preferably 80 parts by mass or more, and still more preferably 100 parts by mass or more with respect to 100 parts by mass of the rubber component. As an upper limit of the compounding quantity of silica, about 120 mass parts can be illustrated, for example.

  When silica is blended, it is preferable to blend a silane coupling agent in combination. The silane coupling agent is not particularly limited as long as it contains sulfur in the molecule, and various silane coupling agents blended with silica in the rubber composition can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide (eg, "Si69" manufactured by Degussa), bis (3-triethoxysilylpropyl) disulfide (eg, "Si75" manufactured by Degussa), bis (2-triethoxysilylpropyl) tetrasulfide (eg, "Si75" manufactured by Degussa); Ethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, sulfide silanes such as bis (2-trimethoxysilylethyl) disulfide, γ-mercaptopropyltri Mercaptosilanes such as methoxysilane, γ-mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, mercaptopropyldimethylmethoxysilane, mercaptoethyltriethoxysilane, 3-octanoylthio-1- And protected mercaptosilanes such as propyltriethoxysilane and 3-propionylthiopropyltrimethoxysilane. It is preferable that the compounding quantity of a silane coupling agent is 2-25 mass parts with respect to 100 mass parts of silicas, More preferably, it is 5-15 mass parts.

  As a vulcanizing agent, sulfur is mentioned as a typical thing. Sulfur may be any conventional sulfur for rubber, and for example, powder sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur and the like can be used.

  As a vulcanization accelerator, a sulfenamide-based vulcanization accelerator, a thiuram-based vulcanization accelerator, a thiazole-based vulcanization accelerator, a thiourea-based vulcanization accelerator, a guanidine-based vulcanization, which are usually used for rubber vulcanization Accelerators such as accelerators and dithiocarbamate accelerators may be used alone or in combination.

  As an anti-aging agent, other than a phenolic anti-aging agent, an aromatic amine anti-aging agent, an amine-ketone anti-aging agent, a dithiocarbamate anti-aging agent, a thiourea anti-aging agent, etc. You may use it as needed.

DESCRIPTION OF SYMBOLS 1 continuous kneading single-screw extruder 2 supply part 3 cylinder 4 screw 5 conveyance part 6 kneading part 7 retention part

Claims (5)

A continuous kneading single-screw extruder for kneading a rubber composition, comprising
A screw, a cylinder disposed on the outer peripheral side of the screw, and a supply unit to which at least a rubber component is supplied;
The screw comprises a screw shaft and a plurality of elements inserted into the screw shaft,
The element has at least a first element constituting a transport section, a second element constituting a kneading section, and a third element constituting a retention section,
The third element is formed such that the spiral blade is in the direction of returning the rubber composition upstream in the screw axial direction,
A continuous kneading single-screw extruder characterized in that a stagnant part is disposed on the downstream side in the screw axial direction of the kneading part.     The continuous kneading single-screw extruder according to claim 1, wherein 0.065 A A / B 2 2 where A is the axial length of the retaining part and B is the axial length of the kneading part.   The continuous kneading single screw extruder according to claim 1 or 2, wherein the rubber composition contains silica.   The continuous kneading single screw extruder according to any one of claims 1 to 3, wherein the rubber composition contains 60 parts by mass or more of silica when the total amount of the rubber component is 100 parts by mass.   The manufacturing method of the rubber composition characterized by using and kneading | mixing the continuous-kneading single-screw extruder in any one of Claims 1-4.

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