JP7119587B2 - Cleaning method of closed type kneader - Google Patents

Description

The present invention relates to a method for cleaning a closed-type kneader.

A rubber composition is obtained by kneading a base rubber as a constituent component and chemicals such as a reinforcing agent using a closed kneader. A Banbury mixer and a kneader are known as this closed type kneader.

The closed type kneader has a kneading chamber containing base rubber and chemicals, a cylindrical ram chamber extending upward from the kneading chamber, a ram moving up and down in the ram chamber, and a kneading chamber. A pair of rotors for kneading base rubber and chemicals is provided.

In the production of a rubber composition using a closed-type kneader, when the base rubber and chemicals are put into the kneading chamber, the ram is lowered. The base rubber and chemicals are pushed into the kneading chamber by this ram. The rotor is rotated and the chemical is kneaded into the base rubber.

In order to obtain a high-quality rubber composition by dispersing chemicals in the base rubber, various studies have been made on a kneading method using an internal kneader (for example, Patent Document 1).

JP 2016-14095 A

In the production of a rubber composition using a closed kneader, the base rubber and chemicals are pushed into the kneading chamber by the ram, as described above. At this time, a part of the chemical scatters and adheres to the internal kneader, although it does not affect the quality of the rubber composition.

In the production of a rubber composition, the base rubber generates heat during kneading. The interior of the kneading chamber may be heated to promote dispersion of the chemicals. For this reason, the surface of the internal kneader tends to be hot. If the melting point of the chemical adhering to the closed kneader is lower than the surface temperature of the closed kneader, the chemical may melt and stick to the closed kneader. When a rubber composition containing a chemical (for example, a vulcanizing agent) having a melting point of around 110° C. is produced, the chemical tends to melt and stick to the internal kneader.

Of the chemicals adhering to the closed type kneader (hereinafter referred to as deposits), the deposits on the upper surface of the ram may fall off the ram and fall into the kneading chamber during the kneading operation. In this case, deposits are mixed into the rubber composition. Incorporation of contaminants affects the quality of the rubber composition, so the internal kneader is periodically washed in order to prevent contamination of the rubber composition with contaminants.

In the cleaning of the closed kneader, the attached matter is usually removed from the closed kneader by blowing off the attached matter with air or scraping off the attached matter with a metal spatula. However, in these conventional cleaning methods, it is difficult to completely remove the deposits, partly because the deposits are melted by the heat of the closed kneader. It takes time and effort to sufficiently remove deposits from the closed kneader. Since the removal of deposits is insufficient and the washing effect does not last, it is necessary to wash the closed kneader frequently in order to prevent contamination of the deposits.

In order to stably produce a high-quality rubber composition, there is a demand for establishment of a cleaning technique capable of efficiently and sufficiently removing chemicals adhering to closed type kneaders.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cleaning method for a closed kneader that can efficiently and sufficiently remove chemicals attached to the closed kneader. and

The method for cleaning a closed kneader according to the present invention includes:
A kneading chamber containing base rubber and chemicals, a ram chamber extending upward from the kneading chamber, a ram moving up and down in the ram chamber, and the base rubber and chemicals introduced into the kneading chamber are kneaded. a pair of rotors,
A method for cleaning a closed type kneader to which a part of the chemicals is scattered when the base rubber and the chemicals are pushed into the kneading chamber by the ram, and the chemicals that are scattered adhere to the mixer,
The method includes a step of using a cleaning device having a nozzle for injecting dry ice in the form of particles, and injecting the dry ice from the nozzle toward the adhering matter on the closed kneader.

Preferably, in this method for cleaning a closed kneader, the dry ice has a particle size of 5 mm or more and 10 mm or less.

Preferably, in this method for cleaning a closed type kneader, the dry ice injection amount is 0.5 kg/min or more and 1.0 kg/min or less.

Preferably, in this method for cleaning a closed type kneader, the dry ice injection time is 20 minutes or more and 40 minutes or less.

Preferably, in this method for cleaning a closed-type kneader, the pressure when the dry ice is injected is 0.2 MPa or more and 0.4 MPa or less.

Preferably, in this method for cleaning a closed-type kneader, the deposit is a chemical adhering to the upper surface of the ram. In this case, it is more preferable that the dry ice is jetted toward the adhering matter with the ram set at its upper limit, and the orientation of the nozzle makes an angle of 30° or more and 60° with respect to the horizontal direction. ° or less is more preferable.

Preferably, in this method for cleaning a closed kneader, the diameter of the nozzle is 20 mm or more and 30 mm or less.

In the method for cleaning a closed type kneader according to the present invention, particulate dry ice is sprayed from the nozzle of the cleaning device toward the chemicals adhering to the closed type kneader, that is, the deposits. Dry ice hits the deposit. This pulverizes and removes the deposits. Even if the deposit is melted, the jet of dry ice cools the deposit. Since the deposits are solidified by cooling, this cleaning method can remove the deposits even if the deposits are melted. Furthermore, this cleaning method can remove deposits by blowing particulate dry ice, which cannot be removed by physical means such as a metal spatula, such as narrow gaps between rams and ram chambers. deposits can also be removed. This cleaning method can efficiently and sufficiently remove the chemicals adhering to the closed kneader. This cleaning method can contribute to preventing contamination of the rubber composition with contaminants. In other words, this cleaning method can contribute to stable production of high-quality rubber compositions.

FIG. 1 is an explanatory diagram schematically showing an example of a Banbury mixer, which is a target of a method for cleaning a closed kneader according to one embodiment of the present invention. FIG. 2 is a diagram for explaining how the Banbury mixer is cleaned. FIG. 3 is a diagram for explaining the direction of the nozzle that injects dry ice.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

A rubber composition is produced in a closed kneader, which is the object of the cleaning method according to one embodiment of the present invention. The rubber composition contains base rubber and chemicals as constituent components.

[Rubber composition]
In this cleaning method, the base rubber contained in the rubber composition is not particularly limited. Examples of the base rubber include natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber (IR), ethylene-propylene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile-butadiene rubber. (NBR) and butyl rubber (IIR). These can be used alone or in combination of two or more. The optimum base rubber is selected considering the specifications of the member to which the rubber composition is applied.

A rubber composition is usually compounded with a plurality of types of chemicals. In this cleaning method, the chemicals contained in this rubber composition are not particularly limited. The chemicals include chemicals generally used as chemicals for rubber compositions, such as reinforcing agents, silane coupling agents, plasticizers, fillers, vulcanizing agents, vulcanization accelerators and antioxidants. The rubber composition is blended with an optimum chemical in an optimum amount, taking into consideration the specifications of the member to which the rubber composition is applied. Although not described in detail, these chemicals include particulate chemicals and liquid chemicals. Among particulate chemicals, there are chemicals that melt when heated (for example, vulcanizing agents having a melting point of 120° C. or less).

In a closed type kneader (hereinafter referred to as kneader), the chemicals are kneaded into the base rubber. Thereby, a rubber composition is obtained. Examples of this kneader include a Banbury mixer and a kneader.

[Kneader]
FIG. 1 shows an outline of the kneader 2. As shown in FIG. The kneader 2 shown in FIG. 1 is a Banbury mixer. This kneader 2 comprises a kneading chamber 4 and a ram chamber 6 .

The kneading chamber 4 accommodates base rubber and chemicals as components of the rubber composition. This kneader 2 has a pair of rotors 8 in a kneading chamber 4 . Each rotor 8 is rotated by a drive means (for example, an electric motor) not shown. In the kneader 2, the rotation of the rotor 8 kneads the base rubber and chemicals introduced into the kneading chamber 4. As shown in FIG.

Although not shown, in this kneader 2, the kneading chamber 4 is further provided with an oil inlet. This oil input portion is used to input a liquid chemical such as a plasticizer into the kneading chamber 4 .

The ram chamber 6 is positioned above the kneading chamber 4 . A ram chamber 6 extends upward from the kneading chamber 4 . This ram chamber 6 is cylindrical. This kneader 2 has a ram 10 in a ram chamber 6 . A ram 10 is supported by a rod 12 . A rod 12 extends upwardly from a top surface 14 of ram 10 . Although not shown, an air cylinder is provided above the ram chamber 6 . In this kneader 2, the rod 12 is moved up and down by this air cylinder. This causes the ram 10 to move up and down within the ram chamber 6 . In the kneader 2 of FIG. 1, the ram 10 is located at its lower limit position. In this kneader 2, the kneading chamber 4 is closed by setting the ram 10 to its lower limit position.

In this kneader 2 , the ram chamber 6 has an inlet 16 . This input port 16 is used to input base rubber, fillers, vulcanizing agents and other chemicals into the kneading chamber 4 . A chemical such as a reinforcing agent to be compounded in a large amount in the rubber composition is introduced into the kneading chamber 4 through another inlet (not shown) provided in the ram chamber 6 . When the base rubber and chemicals are introduced into the kneading chamber 4 through the inlet 16, the ram 10 is set at its upper limit position.

In the production of a rubber composition using this kneader 2, the base rubber and chemicals are weighed according to a preset composition. After weighing, the base rubber and chemicals are introduced into the kneading chamber 4 . After closing, the ram 10 is pushed down to its lower limit position. As a result, the base rubber and chemicals are forced into the kneading chamber 4 and the kneading chamber 4 is closed. The rotor 8 is rotated to knead the base rubber and chemicals introduced into the kneading chamber 4 .

This kneader 2 has a drop door 18 at the bottom of the kneading chamber 4 . When the kneading is completed and the rubber composition is obtained, the ram 10 is pulled up. A drop door 18 is opened and the rubber composition is discharged from the kneading chamber 4 . The rubber composition discharged from the kneading chamber 4 is processed into a plate through a feeder and rolling rolls (not shown).

In the production of the rubber composition using this kneader 2, when the base rubber and the chemicals are pushed into the kneading chamber 4 by the ram 10, part of the chemicals scatter. Most of the scattered chemicals are collected during kneading and put into the kneading chamber 4 again. However, part of the scattered chemicals adheres to the kneader 2, although it does not affect the quality of the rubber composition. In particular, chemicals tend to adhere to the upper surface 14 of the ram 10 that pushes the base rubber and chemicals into the kneading chamber 4 . The present invention is a method for cleaning the kneader 2 to which this chemical is adhered. This cleaning method will be described below.

[Washing method]
In this cleaning method, the kneader 2 to which chemicals are attached is cleaned using a cleaning device 20 . In this cleaning method, the cleaning device 20 is used to remove the chemicals adhering to the kneader 2 , that is, the deposits from the kneader 2 . In this cleaning method, a cleaning device 20 having a nozzle 22 for injecting dry ice particles together with compressed air is used to remove deposits from the kneader 2 . For this cleaning method, a commercially available cleaning device 20 selected in consideration of cleaning performance can be used. An example of this commercially available cleaning device 20 is the product name "IB7/40" manufactured by Karcher.

In this cleaning method, prior to cleaning the kneader 2, as shown in FIG. 2, the ram 10 is lifted and set at its upper limit position. This cleaning method includes setting the ram 10 to its upper limit position. The upper limit position of the ram 10 means the highest position in the lifting range of the ram 10 in the kneader 2 .

In this cleaning method, when the ram 10 is set to its upper limit position, the cleaning device 20 is prepared. That is, this cleaning method includes a step of preparing the cleaning device 20 . In this cleaning method, in the preparation process of the cleaning device 20, the nozzle 22 is set so that the dry ice can be sprayed toward the deposits on the cleaning target location. For example, when cleaning the upper surface 14 of the ram 10, as shown in FIG. In the preparation process of the cleaning device 20, the nozzle 22 may be set so that the dry ice can be sprayed toward the deposits on the cleaning target location. The tip of the tip may be directed toward deposits on the location to be cleaned. Although not shown, in this FIG. 2, the nozzle 22 is attached to the kneader 2 using attachment means configured so that the orientation of the nozzle 22 can be adjusted.

In this cleaning method, when the setting of the nozzle 22 is completed, dry ice particles are jetted from the nozzle 22 toward the adhering matter. That is, this cleaning method includes a step of using the cleaning device 20 to spray particulate dry ice from the nozzle 22 toward the adhering matter on the kneader 2 .

In this cleaning method, particulate dry ice is jetted from the nozzle 22 of the cleaning device 20 toward the chemicals adhering to the kneader 2, that is, the adhering substances. Dry ice hits the deposit. This pulverizes and removes the deposits. Even if the deposit is melted, the jet of dry ice cools the deposit. Since the deposits are solidified by cooling, this cleaning method can remove the deposits even if the deposits are melted. Furthermore, this cleaning method can remove deposits by blowing particulate dry ice, so they cannot be removed by physical means such as a metal spatula. Deposits in narrow gaps can also be removed. In this cleaning method, the chemicals adhering to the closed kneader 2 can be removed efficiently and sufficiently. This cleaning method can contribute to preventing contamination of the rubber composition with contaminants. In other words, this cleaning method can contribute to stable production of high-quality rubber compositions.

In this cleaning method, it is preferable that the particle size of the dry ice jetted toward the adhering matter is 5 mm or more. In this cleaning method, the dry ice effectively pulverizes the adhering matter, resulting in a high cleaning effect. In this cleaning method, the particle diameter of dry ice is preferably 10 mm or less. In this cleaning method, since the dry ice is not too large, all corners of the cleaning target can be cleaned with dry ice. This cleaning method maintains a good cleaning effect. In the present invention, the particle size of dry ice is specified based on a dry ice particle image captured using an imaging means such as a microscope within 15 seconds after sampling the dry ice. Specifically, the major diameter and minor diameter are measured for 100 grains or more of dry ice, and the average value of the major and minor diameters is obtained as the grain size of one grain of dry ice. The average value of the obtained particle sizes is expressed as the particle size of the dry ice.

In this cleaning method, the jetting amount of dry ice jetted from the nozzle 22 toward the adhering matter is preferably 0.5 kg/min or more. As a result, the dry ice effectively pulverizes the adhering matter, resulting in a high cleaning effect. In this cleaning method, the injection amount of dry ice is preferably 1.0 kg/min or less. This keeps the amount of dry ice used appropriately.

In this cleaning method, the jetting time of the dry ice jetted from the nozzle 22 toward the adhering matter is preferably 20 minutes or longer. As a result, the dry ice effectively pulverizes the adhering matter, resulting in a high cleaning effect. In this cleaning method, the dry ice injection time is preferably 40 minutes or less. This keeps the amount of dry ice used appropriately.

In this cleaning method, it is preferable that the pressure when the dry ice is jetted from the nozzle 22 toward the adhering matter is 0.2 MPa or more. In this cleaning method, the dry ice effectively pulverizes the adhering matter, resulting in a high cleaning effect. In this cleaning method, the pressure when the dry ice is injected is preferably 0.4 MPa or less. In this cleaning method, the operator can easily operate the nozzle 22 that injects the dry ice because the pressure during the injection is appropriately suppressed.

In this cleaning method, the shape of the nozzle 22 is cylindrical. In this cleaning method, from the viewpoint of effectively cleaning the kneader 2, the inner diameter of the nozzle 22, that is, the diameter, is preferably 20 mm or more, and preferably 30 mm or less.

As described above, kneading the base rubber and chemicals causes the chemicals to adhere to the kneader 2 , particularly to the upper surface 14 of the ram 10 that pushes the base rubber and chemicals into the kneading chamber 4 . A kneading chamber 4 is located directly below the ram 10 . This cleaning method is preferably applied to remove deposits on the top surface 14 of the ram 10 since deposits on the top surface 14 of the ram 10 are likely to fall into the kneading chamber 4 . In other words, preferably, the deposits that this cleaning method cleans are chemicals deposited on top surface 14 of ram 10 . In this case, since deposits are removed from the upper surface 14 of the ram 10, contamination of the rubber composition with deposits is effectively suppressed.

In the kneader 2 to which this cleaning method is applied, the ram 10 is positioned inside the ram chamber 6 . From the viewpoint of facilitating cleaning of the upper surface 14 of the ram 10, in this cleaning method, the chemical adhering to the upper surface 14 of the ram 10, i. Dry ice is preferably jetted from the nozzle 22 toward the kimono.

As shown in FIG. 2, the upper surface 14 of the ram 10 is sloped. The upper surface 14 is configured to be positioned gradually downward from the opposite side of the inlet 16 toward the inlet 16 side. Therefore, on the upper surface 14 , the inlet 16 side is positioned lower than the opposite side of the inlet 16 .

In this cleaning method, when cleaning the upper surface 14 of the ram 10, from the viewpoint of effectively removing deposits on the upper surface 14 of the ram 10, as shown in FIG. It is preferably provided at a position opposite to the inlet 16 .

FIG. 3 is a diagram for explaining the orientation of the nozzle 22 installed in the kneader 2. As shown in FIG. In FIG. 3 , the dashed line LN is the center line of the nozzle 22 . In this cleaning method, dry ice is jetted from the nozzle 22 in the direction of the center line LN. In this cleaning method, the orientation of the center line LN is the orientation of the nozzle 22 . In FIG. 3, a solid line LH is a virtual line for specifying the orientation of the nozzles 22. As shown in FIG. This virtual line LH extends horizontally. The angle α is the angle formed by the center line LN with respect to the virtual line LH. In this cleaning method, this angle α is the angle that the orientation of the nozzle 22 makes with respect to the horizontal direction.

In this cleaning method, from the viewpoint of effectively cleaning the upper surface 14 of the ram 10, the angle α formed by the nozzle 22 for ejecting dry ice toward the adhering matter with respect to the horizontal direction is preferably 30° or more, and 60°. ° or less is preferred.

As is clear from the above description, the cleaning method for the closed kneader 2 of the present invention can efficiently and sufficiently remove the chemicals adhering to the closed kneader 2 .

The embodiments disclosed this time are illustrative in all respects and are not restrictive. The technical scope of the present invention is not limited to the above-described embodiments, but includes all modifications within the scope of equivalents to the configuration described in the claims.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited only to these Examples.

[Preparation of components]
In order to produce a rubber composition using the kneader shown in FIG. 1, as a base rubber,
・ SBR: "Y031" manufactured by Asahi Kasei Corporation (styrene content = 26% by mass)
・NR: TSR-20
and BR: "BR730" manufactured by JSR (cis content = 95% by mass)
prepared. The blend ratio (SBR/NR/BR) was set at 70/25/5. Furthermore, as a chemical kneaded into this base rubber,
・Silica: “Ultrasil VN3” manufactured by Evonik Tegussa
prepared. Silica was weighed so as to be 60 parts by mass with respect to 100 parts by mass of the base rubber. The following components were prepared as chemicals other than silica.
・ Silane coupling agent: “NXT-Z45” manufactured by Momentive
・ Aromatic oil: “Diana Process AH-24” manufactured by Idemitsu Kosan Co., Ltd.
・Zinc oxide: "Zinc oxide" manufactured by Mitsui Kinzoku Mining Co., Ltd.
・Stearic acid: NOF's stearic acid "Tsubaki"
・ Anti-aging agent: "Altigen 6C" manufactured by Sumitomo Chemical Co., Ltd.
・Wax: "Sannok N" manufactured by Ouchi Shinko Kagaku Co., Ltd.
・ Vulcanizing agent (sulfur): powdered sulfur manufactured by Karuizawa Io Co., Ltd. ・ Vulcanization accelerator a: “Noccellar CZ” manufactured by Ouchi Shinko Chemical Co., Ltd.
・ Vulcanization accelerator b: "Noccellar D" manufactured by Ouchi Shinko Chemical Co., Ltd.
These chemicals were weighed according to the compounding amounts generally set for rubber compositions for tires.

[Example 1]
A rubber composition composed of the components described above was manufactured, and a kneader (closed type kneader manufactured by Kobe Steel, Ltd., kneading chamber capacity: 240 L) was prepared with chemicals adhering to the upper surface of the ram. The upper surface of the ram of this kneader was cleaned using a cleaning device equipped with nozzles for ejecting dry ice particles. For this cleaning, dry ice (30 kg) was sprayed on the deposit for 40 minutes. After cleaning, the condition of the upper surface of the ram was visually confirmed. After confirmation, about 800 tons of rubber composition was manufactured over a further week. After production, the ratio of the number of batches in which contamination with foreign matter was confirmed to the total number of production batches, that is, the rate of occurrence of contamination of the rubber composition was calculated. The results are shown in Table 1 below together with the state of the top surface of the ram immediately before the start of production.

[Comparative Example 1]
As in Example 1, a kneader (closed type kneader manufactured by Kobe Steel, Ltd., kneading chamber capacity: 240 L) was prepared with the chemicals adhering to the upper surface of the ram. After visually confirming the condition of the top surface of the ram without washing the top surface of the ram of this kneader, about 800 tons of the same rubber composition as in Example 1 was produced over a period of one week. After production, the incidence of contamination of the rubber composition was calculated. The results are shown in Table 1 below together with the state of the top surface of the ram immediately before the start of production.

[Comparative Example 2]
As in Example 1, a kneader (closed type kneader manufactured by Kobe Steel, Ltd., kneading chamber capacity: 240 L) was prepared with the chemicals adhering to the upper surface of the ram. The upper surface of the ram of this kneader was cleaned by a conventional method (blowing air and scraping off deposits with a metal spatula). After washing, the condition of the upper surface of the ram was visually observed, and about 800 tons of the same rubber composition as in Example 1 was produced over a period of one week. After production, the incidence of contamination of the rubber composition was calculated. The results are shown in Table 1 below together with the state of the top surface of the ram immediately before the start of production.

[Situation of top surface of ram]
The condition of the top surface of the ram just prior to the start of production was graded based on the following criteria. The results are shown in Table 1 below.
・When chemical adhesion cannot be visually confirmed A
・When there is no accumulation of chemicals, but adhesion of chemicals is confirmed B
・When chemical deposits are confirmed C

As shown in Table 1, it was confirmed that in the examples, the deposits were sufficiently removed by washing and the incidence of contamination of the rubber composition with foreign matter was low compared to the comparative examples. rice field. From this result, the superiority of the present invention is clear.

The technique for cleaning a closed type kneader described above can be applied to cleaning of various kneaders.

2 Kneading machine 4 Kneading chamber
6... Ram chamber 8... Rotor 10... Ram 12... Rod 14... Upper surface of ram 10 16... Input port 22... Nozzle

Claims (9)

A kneading chamber containing base rubber and chemicals, a ram chamber extending upward from the kneading chamber, a ram moving up and down in the ram chamber, and the base rubber and chemicals introduced into the kneading chamber are kneaded. a pair of rotors,
A method for cleaning a closed type kneader to which a part of the chemicals is scattered when the base rubber and the chemicals are pushed into the kneading chamber by the ram, and the chemicals that are scattered adhere to the mixer,
A step of injecting the dry ice from the nozzle toward the adhered matter of the closed kneader using a cleaning device equipped with a nozzle for injecting dry ice in the form of particles,
the deposit is a chemical adhering to the upper surface of the ram;
A method for cleaning a closed-type kneader, wherein in the step of injecting dry ice from the nozzle, the dry ice is injected toward the deposits with the ram set at its upper limit position. 2. The method for cleaning a closed kneader according to claim 1, wherein the dry ice has a particle size of 5 mm or more and 10 mm or less. 3. The method for cleaning a closed kneader according to claim 1 or 2, wherein the injection amount of said dry ice is 0.5 kg/min or more and 1.0 kg/min or less. 4. The method for cleaning a closed type kneader according to claim 1, wherein said dry ice injection time is 20 minutes or more and 40 minutes or less. 5. The method for cleaning a closed kneader according to claim 1, wherein the dry ice is sprayed at a pressure of 0.2 MPa or more and 0.4 MPa or less. 6. The method for cleaning a closed kneader according to claim 1, wherein the direction of said nozzle makes an angle of 30[deg.] or more and 60[deg.] or less with respect to the horizontal direction. The method for cleaning a closed kneader according to any one of claims 1 to 6, wherein the diameter of the nozzle is 20 mm or more and 30 mm or less. The deposit is a chemical that adheres to the upper surface of the ram during production of the rubber composition containing the base rubber and the chemical, and continues to adhere to the upper surface of the ram even after production of the rubber composition. The method for cleaning a closed kneader according to any one of claims 1 to 7. The ram chamber has an inlet used for introducing the base rubber and the chemical into the kneading chamber ,
The upper surface of the ram is configured to be positioned gradually downward from the opposite side of the input port toward the input port side,
9. The method for cleaning a closed kneader according to claim 1, wherein said nozzle is provided on said inlet side.

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