JP7176352B2 - Method for manufacturing rubber member - Google Patents

Description

The present invention relates to a method for manufacturing a rubber member.

Japanese Unexamined Patent Application Publication No. 2015-182269 discloses a method for manufacturing a rubber sheet as an intermediate material for tire rubber members. In this rubber sheet manufacturing method, the base rubber is kneaded with additives in a kneader. A primary rubber composition obtained by kneading is rolled by a calender. This rolling forms the primary rubber composition into a rubber sheet. An anti-adhesion agent is applied to this rubber sheet. The rubber sheet coated with the anti-adhesion agent is dried and cooled by blowing air. The dried and cooled rubber sheets are stacked on pallets.

Japanese Patent Application Laid-Open No. 2015-182269

The primary rubber composition forming the rubber sheet described above is further kneaded. The secondary rubber composition obtained by this kneading is processed into a tire rubber member. However, this secondary rubber composition may be inferior in workability to rubber members for tires. For example, this deterioration in workability is observed in summer when the temperature is high. This reduction in processability lowers the quality of the tire rubber member. This less processable secondary rubber composition is remilled. This remixing can improve the processability of the secondary rubber composition. This re-kneading reduces the productivity of the rubber member.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a rubber member for a tire that is excellent in workability and productivity.

A method for manufacturing a rubber member for a tire according to the present invention comprises:
(A) a step of charging the base rubber and additives into a kneader and kneading them to obtain a primary rubber composition;
(B) forming a rubber sheet from the primary rubber composition;
(C) blowing air having a temperature lower than room temperature onto the rubber sheet to cool the rubber sheet;
(D) a step of putting the rubber sheet into a kneader and further kneading the primary rubber composition to obtain a secondary rubber composition; and (E) a step of obtaining a rubber member from the secondary rubber composition.

Preferably, in the step (A), the kneading is done with an internal mixer. In the step (C), air cooled by an absorption chiller using the waste heat of the internal mixer is blown onto the rubber sheet.

Preferably, in the step (D), the temperature of the rubber sheet fed into the kneader is 30°C or less.

Preferably, between the step (C) and the step (D),
(F) The method further includes a step of measuring the temperature of the rubber sheet and determining whether or not to send the rubber sheet to the step (D).

Preferably, in the step (C), the temperature of the air blown onto the rubber sheet is 10°C or higher and 35°C or lower. The blowing amount of the air is 60 m ³ /min or more.

Preferably, in the step (C), the air blown from a plurality of outlets is blown onto the rubber sheet.

In the method for manufacturing a rubber member for a tire according to the present invention, the rubber sheet is cooled by blowing low-temperature air onto the rubber sheet. The viscosity of the secondary rubber composition obtained from the cooled rubber sheet is low. A secondary rubber composition having a low viscosity is excellent in workability into a rubber member. This secondary rubber composition does not require remilling from the standpoint of processability. This method of manufacturing a rubber member is excellent in workability and productivity.

FIG. 1 is a conceptual diagram showing a manufacturing apparatus used in a method for manufacturing a rubber member for tires according to one embodiment of the present invention. FIG. 2 is a graph of the temperature of a rubber sheet blown with air.

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.

FIG. 1 shows part of a tire rubber member manufacturing apparatus 2 according to the present invention. FIG. 1 shows the manufacturing apparatus 2 together with a rubber sheet R1 molded from a primary rubber composition described later and a rubber sheet R2 molded from a secondary rubber composition described later.

This manufacturing device 2 includes an internal mixer 4 as a first kneader, a first extruder 6, a first calender roll 8, an anti-adhesion agent coating device 10, a cooling device 12, a pallet 14, a second An internal mixer 16 as a second kneader, a second extruder 18 and a second calender roll 20 are provided.

This internal mixer 4 is, for example, a so-called Banbury mixer. Although not shown, the internal mixer 4 includes a kneading chamber, a kneading rotor, and cooling channels for cooling the kneading chamber. The kneading chamber has an openable and closable inlet and an openable and closable outlet. The kneading chamber can be sealed by closing the input port and the discharge port. The kneading rotor is rotatably supported within the kneading chamber. The kneading rotor can knead the base rubber and the additive in the kneading chamber by rotating. This cooling channel is formed along the wall surface of the kneading chamber. The kneading chamber can be cooled by the cooling medium flowing through the cooling channel. The internal mixer 4 has a function of kneading the charged base rubber and additives to form a primary rubber composition.

The first extruder 6 has a hopper 6a, a main body 6b and a screw (not shown). This screw is housed in the body 6b. The hopper 6a is an inlet to the main body 6b. The screw can push out the primary rubber composition introduced into the main body 6b from the discharge port while kneading the primary rubber composition. The first extruder 6 has a function of extruding the primary rubber composition.

The first calender roll 8 comprises a pair of rolls 8a. The pair of rolls 8a is capable of rolling the extruded primary rubber composition to form the primary rubber composition into a rubber sheet R1. The first calendar roll 8 has the function of molding the primary rubber composition into the rubber sheet R1.

The anti-adhesion agent coating device 10 includes an anti-adhesion agent tank 10a. An anti-adhesion agent is stored in the anti-adhesion agent tank 10a. This anti-adhesion agent tank 10a is made so that the rubber sheet R1 can be immersed in this anti-adhesion agent. The anti-adhesion agent coating device 10 has a function of applying an anti-adhesion agent to the surface of the rubber sheet R1.

The cooling device 12 includes a cooling chamber 12a, a plurality of bars 12b, an air handling unit 12c, an absorption chiller 12d, an air pipe 12e, a cooling pipe 12f and a heating pipe 12g.

The cooling chamber 12a has an inlet through which the rubber sheet R1 is fed and an outlet through which the rubber sheet R1 is carried out. A plurality of bars 12b are arranged in the cooling chamber 12a. As shown in FIG. 1, a plurality of bars 12b can suspend the rubber sheet R1 between the entrance and the exit.

The absorption chiller 12d has a function of cooling the cooling medium flowing through the cooling pipe 12f by using the heating medium flowing through the heating pipe 12g as a heat source. The cooling pipe 12f circulates a cooling medium between the air handling unit 12c and the absorption chiller 12d. Although not shown, in the manufacturing apparatus 2, the heating pipe 12g is configured such that the heating medium flowing through the heating pipe 12g is heated by the waste heat of the internal mixer 4. FIG. For example, the heating pipe 12g is configured such that the heating medium and the cooling medium heated in the cooling channel of the internal mixer 4 exchange heat.

Although not shown, this absorption chiller 12d includes an evaporator, an absorber, a regenerator and a condenser.

A cooling pipe 12f is passed through the chamber of the evaporator. The inside of this evaporator is kept at a low pressure. Water is supplied to this evaporator. In the chamber of this evaporator, the supplied water evaporates to generate steam. The evaporating water takes heat of vaporization from the cooling medium in the cooling pipe 12f. Thereby, the cooling medium flowing through the cooling pipe 12f is cooled.

The absorber chamber communicates with the evaporator chamber. An absorbent medium is supplied to the absorber. This absorption medium absorbs water vapor in the evaporation chamber. Lithium bromide is exemplified as this absorption medium.

The regenerator is heated by a heating medium flowing through the heating pipe 12g. An absorbent medium that has absorbed water vapor from the absorber is sent to this regenerator. This absorption medium is heated in the regenerator by the heating medium flowing through the heating pipe 12g. This heating divides the absorbent medium into water vapor and condensed absorbent medium. The condensed absorption medium is fed back to the absorber.

The condenser is supplied with steam from the regenerator. In the condenser the water vapor is cooled back to water. This water is supplied to the evaporator again.

In this manner, the absorption chiller 12d has a function of cooling the cooling medium flowing through the cooling pipe 12f by using the heating medium flowing through the heating pipe 12g as a heat source.

The air handling unit 12c has a function of sucking air and a function of sending the sucked air to the air pipe 12e. The air pipe 12e has a plurality of outlets opening into the interior of the cooling chamber 12a. Although not shown, a plurality of outlets are arranged along the longitudinal direction of the rubber sheet R1.

The internal mixer 16 is, for example, a so-called Banbury mixer. The internal mixer 16 includes a kneading chamber, a kneading rotor, and cooling channels for cooling the kneading chamber. The internal mixer 16 has a configuration similar to that of the internal mixer 4 . The internal mixer 16 has a function of further kneading the supplied primary rubber composition and additives to form a secondary rubber composition.

The second extruder 18 has a hopper 18a, a body 18b and a screw (not shown). The second extruder 18 is configured similarly to the first extruder 6 . The second extruder 18 has the function of extruding the secondary rubber composition.

The second calender roll 20 comprises a pair of rolls 20a. The pair of rolls 20a has a function of rolling the secondary rubber composition extruded by the second extruder 18 to form the secondary rubber composition into a rubber sheet R2.

In this manufacturing apparatus 2, the cooling medium and heating medium are not particularly limited, but water is exemplified as this cooling medium and heating medium.

Here, a method for manufacturing a tire rubber member using this manufacturing apparatus 2 will be described. Here, a tread member forming a tread will be described as an example of a tire rubber member. Here, the tread member will be described as an example, but other tire rubber members such as a sidewall member and a clinch member may be molded from the rubber sheet R2.

In this manufacturing method, base rubber and additives are prepared.

The base rubber and additives are put into the internal mixer 4, and the base rubber and additives are kneaded to obtain a primary rubber composition from the base rubber and additives (step (A )). In this step (A), the base rubber and additives are kneaded at, for example, 120°C to 180°C. The kneading temperature is adjusted by the cooling medium flowing through the cooling channel of the internal mixer 4 .

In the first extruder 6 and the first calender roll 8, the primary rubber composition is formed into a rubber sheet R1 (step (B)). Here, this primary rubber composition is charged into a hopper 6a. The primary rubber composition is kneaded by a screw in the main body 6b and extruded from the ejection port. In this first extruder 6, the primary rubber composition is extruded. This extruded primary rubber composition is roll-molded by the first calender rolls 8 . This primary rubber composition is molded into a rubber sheet R1. This rubber sheet R1 has a long strip shape. This rubber sheet R1 is conveyed to the conveyor 22 and sent to the anti-adhesion agent coating device 10 .

In the anti-adhesion agent coating device 10, the rubber sheet R1 is coated with an anti-adhesion agent. Here, the rubber sheet R1 is immersed in the anti-adhesion agent in the anti-adhesion agent tank 10a. As a result, the anti-adhesion agent is applied to the rubber sheet R1. The coating method of this anti-adhesion agent is not limited to such dip coating. For example, an anti-adhesion agent may be sprayed onto the rubber sheet R1, or may be applied with a roller, a brush, or the like. The rubber sheet R1 is conveyed to the conveyor 24 and sent to the cooling device 12 .

In the cooling device 12, air having a temperature lower than room temperature is blown onto the rubber sheet R1 to cool the rubber sheet R1 (step (C)).

Here, the rubber sheet R1 is fed from the inlet of the cooling device 12 into the cooling chamber 12a. The rubber sheet R1 is suspended from a plurality of bars 12b and sent toward the exit.

The air handling unit 12c sucks ambient air. As described above, the cooling medium flowing through the cooling pipe 12f cools the air sucked by the air handling unit 12c. The air handling unit 12c sends air cooled below room temperature to the air pipe 12e. This low-temperature air is blown out from a plurality of outlets into the cooling chamber 12a. This low-temperature air is blown onto the rubber sheet R1. In this manner, the rubber sheet R1 is dried while being cooled. This rubber sheet R1 is discharged from the outlet of the cooling device 12 and sent to the pallet 14. As shown in FIG.

The rubber sheet R1 is folded and stacked on the mounting surface 14a of the pallet 14. As shown in FIG. In this manner, the rubber sheet R1 is placed on the placement surface 14a. The placed rubber sheet R1 is sent to the internal mixer 16 .

The rubber sheet R1 is put into the internal mixer 16, and the first rubber composition is further kneaded to obtain the second rubber composition (step (D)). The kneading temperature is adjusted by the cooling medium flowing through the cooling channel of the internal mixer 16 . In this step (D), the first rubber composition may be further added with other additives and kneaded. The kneading temperature in this step (D) is, for example, 120°C to 180°C. This secondary rubber composition is sent to the second extruder 18 .

In the second extruder 18 and the second calender rolls 20, the secondary rubber composition is molded into the rubber sheet R2. Here, the secondary rubber composition is charged into the hopper 18a. The secondary rubber composition is kneaded by a screw inside the main body 18b and extruded from the outlet. A second extruder 18 extrudes the secondary rubber composition. This extruded secondary rubber composition is roll-molded by the second calender rolls 20 . The secondary rubber composition is molded into rubber sheet R2. This rubber sheet R2 has a long strip shape.

Although not shown, a tread member is obtained from the rubber sheet R2 (step (E)). Specifically, the rubber sheet R2 is extruded into a strip having a predetermined cross-sectional shape by another extruder (not shown). This strip is cut to a predetermined length. In this manner, a tread member having a prescribed cross-sectional shape and a prescribed length is obtained.

A method of manufacturing a tire using this tread member will now be described. Along with this tread member, other tire rubber members such as sidewall members, clinch members, and inner liner members are prepared. These tire rubber members are combined to form a raw cover (preforming step). This raw cover is put into the mold. The raw cover is pressurized and heated within the mold. Thus, a tire is obtained from this raw cover (vulcanization step).

In this method of manufacturing a tread member, air having a temperature lower than room temperature is blown onto the rubber sheet R1 in step (C). In this manufacturing method, the rubber sheet R1 can be sufficiently cooled even if the room temperature is high. The sufficiently cooled primary rubber composition is kneaded by the internal mixer 16 and a high shearing force acts thereon. The secondary rubber composition obtained by kneading this primary rubber composition has a low viscosity. The rubber sheet R2 formed from this secondary rubber composition has excellent workability when extruded into a tread member. This rubber sheet R2 does not require re-kneading in order to improve workability. This tread member manufacturing method is excellent in productivity.

The rubber sheet R1 has a belt-like sheet shape with a thin thickness relative to its width. In this step (C), air is blown to the rubber sheet R1. Since the rubber sheet R1 has a sheet shape, it is possible to suppress the occurrence of uneven cooling due to air.

In this manufacturing method, in step (C), the waste heat of the internal mixer 4 is used to cool the air in the absorption chiller 12d. In this manufacturing method, the waste heat of the internal mixer 4 is used to cool the rubber sheet R1 by using the absorption chiller 12d. This manufacturing method is excellent in energy efficiency.

Here, the surface temperature of the rubber sheet R1 is defined as temperature Tr. A rubber sheet R2 obtained from the rubber sheet R1 having a low temperature Tr has a low viscosity. This rubber sheet R2 is excellent in workability in subsequent steps. From the viewpoint of this workability, the temperature Tr of the rubber sheet R1 fed into the internal mixer 16 is preferably 30° C. or lower. This temperature Tr is measured at the rubber sheet R1 put into the internal mixer 16 . In the longitudinal direction of the rubber sheet R1, the surface temperature at the center in the width direction is measured at a plurality of points at constant intervals from the front end to the rear end. An average value of surface temperatures measured at multiple locations is obtained. This average value is taken as the temperature Tr of the rubber sheet R1.

Preferably, in this manufacturing method, the temperature Tr of the rubber sheet R1 is measured between the step (C) and the step (D) to determine whether the rubber sheet R1 is sent to the step (D) ( Step (F)). In this step (F), the temperature Tr of the rubber sheet R1 is measured. It is determined whether or not this temperature Tr is a predetermined temperature, for example, 30° C. or less. In this production method, a secondary rubber composition having excellent processability can be stably obtained.

Generally, in the tire manufacturing method, the width of the rubber sheet R1 is 500 mm or more and 1000 mm or less. The thickness of the rubber sheet R1 is 4 mm or more and 10 mm or less. Although the width and thickness of the rubber sheet R1 are not limited to these, from the viewpoint of cooling the rubber sheet R1, the amount of air blown is preferably 60 m ³ /min or more in the cooling step. The temperature of the blown air is preferably 35° C. or lower, more preferably 30° C. or lower, and particularly preferably 25° C. or lower. Thereby, in this step (C), the rubber sheet R1 is properly cooled. A rubber sheet R2 obtained from this rubber sheet R1 can have an appropriate viscosity. On the other hand, from the viewpoint of drying the anti-adhesion agent, the temperature of the blown air is preferably 10° C. or higher.

Here, the temperature of the blown air is preferably 35° C. or lower. An anti-adhesion agent is applied to the surface of the rubber sheet R1. The rubber sheet R1 can be cooled by evaporating the water content of the anti-adhesion agent. For this reason, the temperature Tr of the rubber sheet R1 is preferably 30° C. or less, and the temperature of the air is preferably 35° C. or less.

In this manufacturing method, in step (C), air is blown out from a plurality of outlets, so that the entire rubber sheet R1 can be uniformly cooled. The viscosity of the second rubber composition obtained from this rubber sheet R1 is homogenized.

Here, the method of manufacturing the rubber member for tires using the rubber sheet R2 has been described, but the manufacturing method according to the present invention is not limited to using the rubber sheet R2. In this method for producing a rubber member, it is sufficient that the secondary rubber composition is obtained from the first rubber composition at a temperature lower than room temperature, and the tire rubber member is obtained from this secondary rubber composition.

The manufacturing apparatus 2 used in this manufacturing method preferably includes a temperature sensor for measuring the temperature Tr of the rubber sheet R1, and a controller for controlling the amount and temperature of the air blown by the air handling unit 12c. In step (C), this control device measures the temperature Tr of the rubber sheet R1 discharged from the cooling device 12 with this temperature sensor. The control device determines whether or not the temperature Tr of the rubber sheet R1 is appropriate. The controller controls the amount and temperature of the air blown out by the air handling unit 12c so that the temperature Tr of the rubber sheet R1 is an appropriate temperature, for example, 30° C. or less. Thereby, the temperature Tr of the rubber sheet R1 can be further stabilized.

The effects of the present invention will be clarified by examples below, but the present invention should not be construed in a limited manner based on the description of these examples.

[Test 1]
[Example]
A manufacturing facility of FIG. 1 was prepared. Natural rubber (90.250 PHR) and isoprene rubber (9.750 PHR) were prepared as base rubbers. Carbon (57.700 PHR), oil (2.5 PHR) and other compounding agents (20.325 PHR) were prepared as additives. This base rubber and additives were kneaded using this manufacturing apparatus to obtain a first rubber composition. This first rubber composition was formed into a rubber sheet R1. A temperature Tr of the rubber sheet R1 discharged from the cooling device was measured. The room temperature at this time exceeded 35°C.

[Comparative example]
Without operating the absorption refrigerator of the cooling device, the air taken in from the outside air was directly blown onto the rubber sheet R1. Otherwise, rubber sheet R1 was produced in the same manner as in Example. A temperature Tr of the rubber sheet R1 discharged from the cooling device was measured.

[Evaluation results]
FIG. 2 shows transition of the temperature Tr of the rubber sheet R1 of the comparative example and transition of the temperature Tr of the rubber sheet R1 of the example. A double-headed arrow Pc in FIG. 2 represents the period during which the rubber sheet R1 of the comparative example was manufactured. A double-headed arrow Pe in FIG. 2 represents the period during which the rubber sheet R1 of the example was manufactured. The average temperature of the rubber sheet R1 of the comparative example was 33°C, and the average temperature of the rubber sheet R1 of the example was 28°C.

[Test 2]
[Example]
A manufacturing facility of FIG. 1 was prepared. Using this manufacturing apparatus, a rubber sheet R2 was manufactured in a room where the room temperature exceeded 35° C., using the same base rubber and additive as in Test 1.

[Comparative example]
Without operating the absorption refrigerator of the cooling device, the air taken in from the outside air was directly blown onto the rubber sheet R1. Otherwise, rubber sheet R2 was produced in the same manner as in Example.

[Temperature and Viscosity]
The temperature Tr and Mooney viscosity V1 of the rubber sheet R1, the Mooney viscosity V2 of the rubber sheet R2, and the viscosity difference (V2-V1) were measured for the examples and the comparative examples. Mooney viscosity V1 and Mooney viscosity V2 were measured at 130° C. according to JIS K6300. The results are shown in Table 1. The smaller the temperature Tr and the Mooney viscosity V2, the better.

As shown in Table 1, in the production method of the example, the Mooney viscosity V2 of the rubber sheet R2 is lower than in the production method of the comparative example. The production methods of the examples are highly evaluated. From this evaluation result, the superiority of the present invention is clear.

The method described above can be widely applied to the production of rubber members for tires.

2... Manufacturing device 4, 16... Internal mixer 6... First extruder 8... First calender roll 10... Anti-adhesive coating device 12... Cooling device 12c... Air handling unit 12d... Absorption chiller 14... Pallet 18... Second extruder 20... Second calendar roll

Claims (5)

(A) a step of charging the base rubber and additives into a kneader and kneading them to obtain a primary rubber composition;
(B) forming a rubber sheet from the primary rubber composition;
(C) blowing air having a temperature lower than room temperature onto the rubber sheet to cool the rubber sheet;
(D) a step of putting the rubber sheet into a kneader and further kneading the primary rubber composition to obtain a secondary rubber composition; and (E) a step of obtaining a rubber member from the secondary rubber composition. ,
In the step (A), kneading is performed with an internal mixer,
A method of manufacturing a rubber member for a tire, wherein in the step (C), air cooled by an absorption chiller using waste heat of the internal mixer is blown onto the rubber sheet . 2. The manufacturing method according to claim 1, wherein in the step (D), the temperature of the rubber sheet introduced into the kneader is 30[deg.] C. or lower. Between the step (C) and the step (D),
3. The manufacturing method according to claim 1 , further comprising the step of (F) measuring the temperature of the rubber sheet and determining whether or not to send the rubber sheet to the step (D). 4. The method according to any one of claims 1 to 3, wherein in the step (C), the temperature of the air blown onto the rubber sheet is 10°C or higher and 35°C or lower, and the blowing amount of the air is ⁶⁰ m3/min or more. manufacturing method. 5. The manufacturing method according to any one of claims 1 to 4, wherein in the step (C), the air blown from a plurality of outlets is blown onto the rubber sheet.

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