JP2016014095A - Method for kneading rubber material for tire and method for producing tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for kneading a rubber material for a tire, capable of producing a rubber material for a tire which can sufficiently exhibit targeted physical properties of rubber and preventing a decrease in yield, by suppressing aggregation of silica and uniformly dispersing the silica in the rubber material for a tire, and to provide a method for producing a tire using the kneading method.SOLUTION: Provided is a method for kneading a rubber material for a tire comprising a step of adding silica to a rubber material for a tire and kneading the mixture by using a Banbury mixer, where addition of the silica in the Banbury mixer is performed in small divided portions. Also provided are the method for kneading a rubber material for a tire where silica is added in the Banbury mixer at an addition rate of 5 to 15 kg/5 sec, and the method for kneading a rubber material for a tire where an on-off valve is installed on an addition pipe for adding silica in the Banbury mixer, and performing addition of the silica in the Banbury mixer in small divided portions by opening and closing of the on-off valve.

Description

  The present invention relates to a method for kneading a tire rubber material compounded with silica, and a tire component produced from a tire rubber material kneaded using the kneading method for a tire rubber material. The present invention relates to a tire manufacturing method for manufacturing a tire.

  Conventionally, for the kneading of rubber materials for tires, a Banbury mixer has been used in which a strong shearing action is applied to the raw rubber by a pair of left and right kneading rotors rotating in different directions in the kneading chamber to plasticize and melt. Using this Banbury mixer, various kinds of fillers and additives are efficiently kneaded into the raw rubber and mixed and dispersed to produce various quality rubber materials for tires (for example, Patent Document 1).

  FIG. 2 is a schematic configuration diagram of the Banbury mixer. The Banbury mixer 1 includes a kneading chamber 12, a pair of left and right kneading rotors 16a and 16b rotatably inserted into the kneading chamber 12, a material supply cylinder 20 standing above the kneading chamber 12, and the material supply cylinder. A floating weight (ram) 22 is provided in the inside 20 so as to be movable up and down. The kneading chamber 12 is housed inside a chamber (not shown).

  When kneading is performed using this Banbury mixer 1, various materials supplied into the material supply cylinder 20 are pushed into the kneading chamber 12 by lowering the floating weight 22. Then, various materials in the kneading chamber 12 are kneaded by rotating the kneading rotors 16a and 16b.

JP 2002-11336 A

  However, silica that is frequently added to rubber materials for tires (especially tread rubber) has the property of being more easily aggregated than other materials such as carbon, and forms aggregates during kneading. There is.

  Once silica forms an agglomerate, it is difficult to sufficiently disperse by subsequent kneading, and due to a decrease in silica dispersion efficiency, the rubber material for tires after production cannot exhibit the target rubber physical properties and is discarded. The disposal may cause a decrease in yield.

  Therefore, the present invention can produce a rubber material for a tire that can sufficiently exhibit the target rubber properties by suppressing the aggregation of silica and uniformly dispersing the silica in the tire rubber material. It is an object of the present invention to provide a method for kneading a rubber material for a tire that can prevent a decrease in yield and a tire manufacturing method using the kneading method.

The invention described in claim 1
A method for kneading a tire rubber material, in which silica is added to a tire rubber material and kneaded using a Banbury mixer,
A method for kneading a rubber material for tires, characterized in that the introduction of the silica into the Banbury mixer is performed in small portions.

The invention described in claim 2
The tire rubber material kneading method according to claim 1, wherein the silica is charged into the Banbury mixer at a charging speed of 5 to 15 kg / 5 sec.

The invention according to claim 3
2. An on-off valve is provided in an introduction pipe for introducing the silica into the Banbury mixer, and the introduction of the silica into the Banbury mixer is performed in small portions by opening and closing the on-off valve. 2. A method of kneading a tire rubber material according to 2.

The invention according to claim 4
A kneading step of kneading the tire rubber material using the tire rubber material kneading method according to any one of claims 1 to 3;
A tire constituent material is produced using the tire rubber material obtained by the kneading step, and a raw tire is molded using the produced tire constituent material, and a raw tire molding step,
And a vulcanizing step for vulcanizing the green tire.

  According to the present invention, it is possible to produce a tire rubber material capable of sufficiently exerting target rubber physical properties by suppressing aggregation of silica and uniformly dispersing silica in the tire rubber material. It is possible to provide a method for kneading a tire rubber material capable of preventing a decrease in yield and a tire manufacturing method using the kneading method.

It is a schematic block diagram which shows the structure of the part relevant to the silica injection | pouring of the Banbury mixer used for the kneading | mixing method of the rubber material for tires which concerns on one embodiment of this invention. It is a schematic block diagram of the Banbury mixer used for the kneading | mixing method of the rubber material for tires.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

  As a result of studying a phenomenon in which agglomerates of silica are formed during kneading, the present inventor has found that this phenomenon is likely to occur when a large amount of silica is added at a time.

  Specifically, in the conventional method for kneading a rubber material for tires, silica and carbon are weighed by a measuring instrument, and a large amount of the raw rubber is poured into a kneading chamber of a Banbury mixer at a time. Thus, it was found that when silica is added in a large amount per time, the silicas come into contact with each other and aggregates are easily formed.

  The present invention has been made on the basis of this knowledge, and when kneading a rubber material for tires containing silica with a Banbury mixer, a large amount of silica is not added at a time, but divided into small portions. This is a method of kneading the tire rubber material to be introduced. Thereby, since it can knead | mix, disperse | distributing a silica appropriately, formation of the aggregate of a silica can be suppressed and the rubber material for tires which can fully exhibit the target rubber physical property can be produced.

  Hereinafter, the method for kneading the tire rubber material according to the present embodiment will be specifically described.

1. Banbury Mixer FIG. 1 is a schematic configuration diagram showing a configuration of a portion related to silica charging of a Banbury mixer used in the method for kneading a tire rubber material according to the present embodiment.

  This Banbury mixer 1 is, like the conventional Banbury mixer, a kneading chamber 12, a pair of left and right kneading rotors 16 a and 16 b that are rotatably inserted into the kneading chamber 12, and a material standing above the kneading chamber 12. A supply cylinder 20 and a floating weight 22 inserted into the material supply cylinder 20 so as to be movable up and down are provided.

  A measuring instrument 2 for measuring a material such as silica or carbon is attached to the material supply cylinder 20 via a charging pipe 4. The charging pipe 4 is provided with a measuring damper 6 for measuring with the measuring instrument 2 and a back wind damper 8 for preventing negative pressure.

  Further, the material supply cylinder 20 is provided with a hopper 7 that can be freely opened and closed, and the raw rubber G and the compounded chemical C conveyed from the material input conveyor 5 are input into the material supply cylinder 20 from the hopper 7 ( (See FIG. 2).

  As shown in FIG. 1, the Banbury mixer 1 according to the present embodiment is a conventional Banbury mixer in that an opening / closing valve 10 is provided in an input pipe 4 for supplying silica or carbon from a measuring instrument 2 to a material supply cylinder 20. And different.

  The on-off valve 10 is provided on the downstream side of the metering damper 6 and the reverse wind damper 8 in the charging pipe 4, and is connected to a control unit (not shown) that controls the operation of the Banbury mixer 1. Then, by controlling the opening and closing of the on-off valve 10 based on the signal from the control unit, the silica measured by the measuring instrument 2 can be divided into small portions and put into the material supply cylinder 20.

  In the present embodiment, the floating weight 22 is also connected to the control unit, and is configured so that the floating weight 22 rises in conjunction with a signal for opening the on-off valve 10 when silica is charged.

2. Method for Kneading Tire Rubber Material A method for kneading a tire rubber material using the Banbury mixer 1 having the above configuration will be described. The blending ratio here is set so that the input amount of the other materials falls within the range of 100 to 400 PHR (Per Hundred Rubber) with respect to the input amount of the raw rubber.

  First, the measured raw rubber G and the compounded chemical C are conveyed by the material charging conveyor 5 and charged into the material supply cylinder 20 from the hopper 7, and the oil measured by the oil meter 3 is directly charged into the kneading chamber 12. (See FIG. 2). At this time, as the raw rubber G, polymer type natural rubber and synthetic rubber are generally used.

  Then, the amount of carbon input is measured in the measuring instrument 2, and after the carbon is input into the material supply cylinder 20, the floating weight 22 is lowered. As a result, the raw rubber, compounded chemical, and carbon in the material supply cylinder 20 are pushed into the kneading chamber 12, and the kneading rotors 16a and 16b are rotated to start kneading.

  On the other hand, in the measuring instrument 2, the amount of silica charged is measured. At this time, the amount of silica introduced is preferably set in the range of 10 to 150 PHR. For example, when 200 kg of raw material rubber is kneaded, the amount of silica charged is set to 20 to 80 kg.

  Then, while continuing the kneading of the raw rubber, the opening and closing valve 10 provided in the charging pipe 4 is controlled to adjust the charging speed, and the silica in the measuring instrument 2 is divided little by little while supplying the material. Put into the cylinder 20.

  At this time, the floating weight 22 rises in conjunction with the opening timing of the on-off valve 10, so that silica is appropriately charged into the material supply cylinder 20. Then, when the on-off valve 10 is closed and the introduction of silica is stopped, the floating weight 22 is lowered to push the silica in the material supply cylinder 20 into the kneading chamber 12.

  Materials such as raw rubber, silica, and carbon charged into the kneading chamber 12 are kneaded by the rotation of the kneading rotors 16a and 16b. Then, while continuing the kneading, the introduction of silica is divided and repeated little by little, and all the silica in the meter 2 is introduced into the kneading chamber 12.

  As described above, while kneading the raw rubber and other materials, by adding the silica in small portions, it is possible to suppress the silica from aggregating and uniformly disperse in the raw rubber. . As a result, the tire rubber material having the desired rubber properties can be kneaded stably, so that the disposal of the material in the tire manufacturing process can be reduced and the yield can be prevented from decreasing.

  In addition, when a large amount of silica is charged at a time as in the prior art, not only agglomerates are formed, but also a phenomenon that silica is ejected from the inlet of a Banbury mixer may occur. In the method for kneading a tire rubber material according to the present embodiment, by introducing silica in small amounts, generation of the silica spray can be appropriately prevented, and the environment around the Banbury mixer can be improved.

  In addition, when the input speed, which is the input amount of silica per hour, is slower than 5 kg / 5 sec, there is a problem that the production efficiency is lowered, and when it exceeds 15 kg / 5 sec, an agglomerate of silica may be formed. There is. For this reason, it is preferable to set the charging speed of silica to 5 to 15 kg / 5 sec.

  In addition, since the tire rubber material produced according to the present embodiment has stable rubber properties as described above, by vulcanizing a raw tire molded using this tire rubber material, A pneumatic tire excellent in quality can be manufactured.

  For example, as shown in FIG. 2, the tire rubber material kneaded in the kneading chamber 12 is discharged out of the kneading chamber 12 when a drop door 17 provided at the bottom of the kneading chamber 12 is opened.

  The discharged tire rubber material is extruded from an extruder 66 and then rolled into a sheet-like tire constituent material by a rolling roller 68. Thereafter, the tire constituent material is applied with an anti-adhesive agent on the surface, cooled and dried by the cooling / drying roller group 70, and folded on the storage table 72.

  Then, the tire constituent material on the storage table 72 is conveyed to the next step, used for forming a raw tire, and a pneumatic tire is manufactured by vulcanizing the formed raw tire.

1. Examples and Comparative Examples Rubber materials for tires were kneaded using a Banbury mixer with a capacity of 270 L and a kneading rotor of 4 WN. The total amount of silica charged was 90 PHR, and the silica was weighed and charged in three stages of X-kneading, Y-kneading, and Z-kneading. The amount of X kneading is 60 PHR, the amount of Y kneading is 20 PHR, and the amount of Z kneading is 10 PHR.

(1) Example In each stage, the metered silica was introduced at a rate of 15 kg / 5 sec, and divided into small portions.

(2) Comparative Example 1
Silica weighed at each stage was added to the entire amount at the same time as raw rubber and carbon.

(3) Comparative Example 2
Only in the X kneading in which 60 PHR of silica was added, the amount of silica was divided into 45 PHR and 15 PHR, and the remaining Y kneading and Z kneading were simultaneously added to the raw rubber and carbon at the same time.

2. Evaluation Method As an index for confirming the aggregation of silica, the gel content of the rubber material for tire after kneading was measured. This gel content was measured by dissolving a rubber in toluene and calculating the ratio from its weight and the initial weight. The results are shown in Table 1.

  Moreover, ML variation (%) and MH variation (%) were measured as an index for confirming rubber variation. ML variation and MH variation were calculated by dividing the standard deviation of the values measured with a curast meter by the average value. The results are shown in Table 1.

  In addition, with respect to the states of “silica ejection” and “dispersion”, the case of improvement was evaluated as “◯”, the case of deterioration as “X”, and the case of similar degree as “Δ”. did. The results are shown in Table 1.

  From Table 1, in the example in which silica was added in small portions, the gel content, ML variation, and MH variation were all kept low, silica could be dispersed properly, and silica ejection It was confirmed that it can be prevented appropriately.

  While the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1 Banbury mixer 2 Metering device 3 Oil metering device 4 Feeding pipe 5 Material feeding conveyor 6 Weighing damper 7 Hopper 8 Back wind damper 10 On-off valve 12 Kneading chamber 16a, 16b Kneading rotor 17 Drop door 20 Material supply cylinder 22 Floating weight 66 Extruder 68 Rolling roller 70 Cooling / drying roller group 72 Storage table C Compound chemical G Raw rubber

Claims (4)

A method for kneading a tire rubber material, in which silica is added to a tire rubber material and kneaded using a Banbury mixer,
A method for kneading a rubber material for tires, wherein the introduction of the silica into the Banbury mixer is performed in small portions.   The method for kneading a tire rubber material according to claim 1, wherein the silica is added to the Banbury mixer at a charging speed of 5 to 15 kg / 5 sec.   2. An on-off valve is provided in an introduction pipe for introducing the silica into the Banbury mixer, and the introduction of the silica into the Banbury mixer is performed in small portions by opening and closing the on-off valve. 2. A method for kneading the tire rubber material according to 2. A kneading step of kneading the tire rubber material using the tire rubber material kneading method according to any one of claims 1 to 3;
A tire constituent material is produced using the tire rubber material obtained by the kneading step, and a raw tire is molded using the produced tire constituent material,
And a vulcanizing step for vulcanizing the green tire.

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