JP7046309B2 - Method for manufacturing rubber composition - Google Patents

Description

The present invention relates to a method for producing a rubber composition containing a rubber component having a small blending ratio of natural rubber as the rubber component.

Pneumatic tires have traditionally been manufactured using various rubber members such as tread rubber. These rubber members are usually manufactured by molding a rubber composition kneaded according to a formulation formulated according to each required property.

Specifically, a base kneading step in which the compounding material excluding the rubber component and the vulcanizing chemical is put into a closed type kneader, kneaded until the specified rubber temperature is reached, and then the kneaded rubber (kneaded rubber) is discharged. The rubber composition is formed by a finishing kneading step in which the vulcanizing chemicals are put into a closed kneader together with the discharged and cooled kneaded rubber, kneaded until the specified rubber temperature is reached, and then the kneaded rubber is discharged. Manufacture.

At this time, the viscosity of the obtained rubber composition needs to be sufficiently reduced in consideration of the moldability of the rubber member.

In the conventional rubber compounding, a rubber component containing natural rubber as a main component is used from the viewpoint of wear resistance, and the molecular weight of the natural rubber is reduced by adding a deliquescent agent. Therefore, the above-mentioned base kneading is performed. The viscosity of the rubber member was sufficiently reduced in the process and the finish kneading process.

However, in recent years, there have been increasing demands from users for improving wet grip and cut resistance of pneumatic tires, and in order to meet these demands, the amount of natural rubber as a rubber component has been reduced while synthetic. It is being considered to increase the amount of rubber (see, for example, Patent Documents 1 and 2).

In this way, in the case of a rubber compound in which the amount of natural rubber is reduced in the rubber component, the rubber composition can be reduced even if the natural rubber is kneaded using a decoction agent to reduce the viscosity of the rubber composition as in the conventional case. It is difficult to obtain a sufficient viscosity reducing effect for the entire object.

Therefore, prior to the finish kneading process, the kneaded rubber obtained in the base kneading process is put into the closed kneading machine again and kneaded to apply a shearing force to the kneaded rubber to further reduce the viscosity (remill). Kneading process).

Japanese Unexamined Patent Publication No. 2009-681 Japanese Unexamined Patent Publication No. 2016-56236

However, as described above, when the remill kneading step is provided between the base kneading step and the finishing kneading step and the kneading is performed in three stages, the kneading process takes time and the workability is deteriorated. In addition, the reduction in viscosity of the rubber composition has not yet been sufficient.

Therefore, the present invention provides a rubber composition manufacturing technique capable of producing a rubber composition having a sufficiently reduced viscosity without taking time for kneading, even if the amount of natural rubber is small. The challenge is to provide.

The present inventor has conducted diligent studies and found that the above-mentioned problems can be solved by the invention described below, and has completed the present invention.

The invention according to claim 1 is
A sealed type containing 100 PHR, a rubber component composed of natural rubber of 40 PHR or less and synthetic rubber of 60 PHR or more, carbon black 30 PHR to 100 PHR, a deliquescent agent of 0.3 PHR or more, and a predetermined amount of vulcanizing chemicals. A method for producing a rubber composition, which is a method for producing a rubber composition by kneading using a kneader.
The rubber component and the compounding material excluding the vulcanizing chemical from the compounding material were simultaneously put into the closed kneader and kneaded until the predetermined rubber temperature was reached, and then the kneaded rubber was kneaded at 150 ° C. The base kneading process of discharging from the closed type kneader at the above temperature and
It is provided with a finish kneading step in which the entire amount of rubber obtained in the base kneading step is charged into a closed kneader, and the vulcanizing chemicals are charged and kneaded at a kneading temperature of 90 to 110 ° C. It is a method for producing a characteristic rubber composition.

The invention according to claim 2 is
The base kneading process
A step of putting the compounding material excluding the carbon black and the vulcanizing chemical together with the rubber component into the closed kneader and kneading until the kneading temperature reaches 110 to 130 ° C.
It is characterized by comprising a step of additionally adding the carbon black, further kneading it until it reaches a predetermined rubber temperature, and discharging the kneaded rubber from the closed type kneader at a temperature of 150 ° C. or higher. The method for producing a rubber composition according to claim 1 .

The invention according to claim 3 is
The method for producing a rubber composition according to claim 1 or 2, wherein the synthetic rubber is styrene-butadiene rubber.

The invention according to claim 4 is
The method for producing a rubber composition according to claim 3, wherein the styrene-butadiene rubber is an emulsion-polymerized styrene-butadiene rubber.

The invention according to claim 5 is
The method for producing a rubber composition according to any one of claims 1 to 4, wherein the closed-type kneader is a Banbury mixer.

The invention according to claim 6 is
The method for producing a rubber composition according to any one of claims 1 to 5, wherein the filling rate of the rubber component and the compounding material in the closed kneader is 60 to 80%. Is.

The invention according to claim 7 is
Air using the rubber composition produced by the method for producing a rubber composition according to any one of claims 1 to 6 to form a rubber member for a pneumatic tire. This is a method for manufacturing a rubber member for a tire.

The invention according to claim 8 is
The method for manufacturing a rubber member for a pneumatic tire according to claim 7, wherein the rubber member for a pneumatic tire is a tread rubber.

The invention according to claim 9 is
A method for manufacturing a pneumatic tire, which comprises manufacturing a pneumatic tire using the rubber member for a pneumatic tire manufactured by the method for manufacturing a rubber member for a pneumatic tire according to claim 7 or 8. be.

According to the present invention, there is a technique for producing a rubber composition capable of producing a rubber composition having a sufficiently reduced viscosity without taking a long time for kneading even if the amount of natural rubber is small. Can be provided.

[1] About the present invention The present inventor has conducted various experiments and studies on solving the above problems.

Specifically, in the production of a rubber composition containing a rubber having a small amount of natural rubber, a kneading method capable of sufficiently reducing the viscosity of the rubber composition without providing a remill kneading step was enthusiastically studied.

As described above, in the production of a rubber composition containing a rubber having a small amount of natural rubber, when the base kneading is performed as in the conventional case, the natural rubber is kneaded using a decoction agent to make the rubber composition. Even if the viscosity of the kneaded rubber is reduced, the viscosity of the entire kneaded rubber cannot be sufficiently reduced. However, it takes time to knead.

Therefore, the present inventor has investigated a method for producing a rubber composition having a sufficiently reduced viscosity without providing this remill kneading step, and even if the amount of natural rubber is small, a specific rubber composition can be produced. It has been found that a sufficient viscosity reducing effect can be obtained in a short time when kneading under kneading conditions, and the present invention has been completed.

That is, as the rubber compound for the purpose of improving the wet grip property and the cut resistance, which is the object of the present invention, a rubber component having a small amount of natural rubber is used, specifically, natural rubber of 40 PHR or less and 60 PHR or more. A rubber compound containing 100 PHR of a rubber component composed of the synthetic rubber of the above, a compound material containing carbon black 30 PHR to 100 PHR, and a deliquescent agent of 0.3 PHR or more is used.

Then, as a result of examining the kneading conditions of the rubber compound having a small amount of natural rubber in such a rubber component, in the base kneading process, the compounding material excluding the vulcanizing chemicals from the rubber component and the compounding material is simultaneously kneaded in a closed type. After putting it in the machine and kneading it until it reaches the specified rubber temperature, the kneaded rubber is discharged from the closed type kneader at a temperature of 150 ° C. or higher to obtain a kneaded rubber whose viscosity is sufficiently reduced. I found that I could do it.

Since the kneaded rubber obtained in the base kneading process has already sufficiently reduced the viscosity of the kneaded rubber, it does not require the conventional remill kneading process and is similar to the kneading of a rubber compound containing a large amount of natural rubber. In addition, a rubber composition having an appropriate viscosity can be obtained by directly proceeding to the finishing kneading step and kneading with a vulcanization chemical (sulfur, vulcanization accelerator).

That is, the present invention
A rubber for producing a rubber composition by kneading a rubber component 100 PHR containing 0 to 40 PHR of natural rubber and a compounding material containing carbon black 30 PHR to 100 PHR and a frothing agent of 0.3 PHR or more using a closed kneader. It is a method for producing a composition.
The rubber component and the compounding material excluding the vulcanizing chemicals from the compounding material are simultaneously put into the closed kneader and kneaded until the predetermined rubber temperature is reached, and then the kneaded rubber is heated to 150 ° C. or higher. The base kneading process of discharging from the closed type kneader at the temperature of
It is provided with a finishing kneading step in which the entire amount of rubber obtained in the base kneading step is charged into a closed kneader, sulfur and a vulcanization accelerator are charged, and the rubber is kneaded at a kneading temperature of 90 to 110 ° C. This is a method for producing a rubber composition.

As described above, in the present invention, even if the amount of natural rubber is small, it is not necessary to provide a remill kneading step, so that the rubber composition is sufficiently reduced in viscosity without taking time for kneading. You can make things.

Then, as a result of further study by the present inventor, in the above-mentioned base kneading process, carbon black is added at the same time as other compounding materials when the rubber component is added to the closed kneader. It was found that when the base kneading process was divided into two processes and only carbon black was added later, it was possible to further reduce the viscosity and shorten the kneading time.

That is, in the case where carbon black is added at the same time as the rubber component, the present inventor inhibits the dehulling reaction of the decomposing agent to the rubber component other than natural rubber by the carbon black, and the effect of the decomposing agent is maximized. It has been found that it is preferable to knead the carbon black until the kneading temperature reaches 110 to 130 ° C. before adding the carbon black.

Specifically, in the above base kneading process, the compounding material excluding carbon black and vulcanizing chemicals is put into a closed kneader together with the rubber component and the deliquescent agent until the kneading temperature reaches 110 to 130 ° C. By dividing into a step of kneading and a step of adding carbon black and further kneading until a predetermined rubber temperature is reached, and discharging the kneaded rubber from the closed type kneader at a temperature of 150 ° C. or higher. It is possible to further reduce the viscosity and shorten the kneading time.

That is, when kneading without adding carbon black, the puckering reaction of the puckering agent is not hindered by the carbon black, the effect of the puckering agent is maximized, and the viscosity of the kneaded rubber is sufficiently lowered. Can be made to. Then, since carbon black is additionally added in a state where the viscosity is sufficiently lowered and the base kneading process proceeds, the same discharge temperature and the same base kneading time (total) as in the case of base kneading without dividing into two processes are performed. When kneaded with, the viscosity is further lowered.

Further, since the carbon black is added in a state where the viscosity is sufficiently lowered, it is equivalent without raising the kneading temperature to the discharge temperature when the base is kneaded without dividing into two steps in the subsequent base kneading process. Since the viscosity of is obtained, the base kneading time can be further shortened.

[2] Embodiment of the present invention Hereinafter, the above-mentioned invention will be specifically described based on the embodiment of the present invention.

1. 1. Various materials used in the present embodiment As described above, the rubber composition produced in the present embodiment has a rubber composition capable of improving the wet grip property and the cut resistance of the pneumatic tire. It is a product and is manufactured by appropriately blending and kneading each of the following materials.

(1) Rubber component In the present embodiment, as the rubber component, a rubber component composed of a natural rubber having a rubber component of 100 PHR of 40 PHR or less and a synthetic rubber having a rubber component of 60 PHR or more is used. If the natural rubber in the rubber component 100 PHR exceeds 40 PHR, there is a risk that sufficient wet grip and cut resistance cannot be ensured in the rubber member made from the kneaded rubber composition. The composition of the preferable rubber component is 0 to 30 PHR for natural rubber and 70 to 100 PHR for synthetic rubber.

The natural rubber is not particularly limited, and not only natural rubbers commonly used in the rubber industry such as SIR20, RSS # 3, and TSR20, but also epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and deproteinized natural rubber. Modified natural rubber such as (DPNR) can also be used. These natural rubbers can be used alone, but two or more of them may be used in combination.

The synthetic rubber is also not particularly limited, and is styrene butadiene rubber (SBR), butadiene rubber (BR), styrene isoprene copolymer rubber, isoprene rubber (IR), butyl rubber (IIR), chloroprene rubber (CR), and acrylonitrile butadiene. Rubber (NBR), butyl halide rubber (X-IIR), halides of copolymers of isobutylene and p-methylstyrene and the like can be used. Among these, it is preferable to use SBR in consideration of the balance between wet grip property, cut resistance and wear resistance.

(2) Carbon black Carbon black functions as a reinforcing agent, and in the present embodiment, 30 to 100 PHR is used with respect to 100 PHR of the rubber component. If it is less than 30 PHR, a sufficient reinforcing effect is not exhibited, and if it exceeds 100 PHR, the dispersibility in the rubber component may deteriorate.

The carbon black is also not particularly limited, and carbon black generally used in the rubber industry such as GPF, FEF, HAF, ISAF, SAF can be used, and can be used alone, but two or more kinds can be used. May be used together.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 100 m ² / g or more, more preferably 105 m ² / g or more, further preferably 110 m ² / g or more, and particularly preferably 130 m ² / g or more. preferable. Below 100 m ² / g, the wet grip performance tends to deteriorate. On the other hand, the N ₂ SA is preferably 600 m ² / g or less, more preferably 250 m ² / g or less, and even more preferably 180 m ² / g or less. If it exceeds 600 m ² / g, it is difficult to obtain good dispersion, and the wear resistance tends to decrease.

The amount of dibutyl phthalate (DBP) oil absorbed by carbon black is preferably 50 ml / 100 g or more, and more preferably 100 ml / 100 g or more. If it is less than 50 ml / 100 g, sufficient wear resistance may not be obtained. On the other hand, the DBP is preferably 250 ml / 100 g or less, more preferably 200 ml / 100 g or less, and even more preferably 135 ml / 100 g or less. If it exceeds 250 ml / 100 g, the wet grip performance may deteriorate.

(3) Crushing agent The decompressing agent is used for the purpose of reducing the viscosity of the rubber and shortening the kneading time, and in the present embodiment, 0.3 PHR or more is used for 100 PHR of the rubber component. If it is less than 0.3 PHR, the effect of reducing the viscosity cannot be obtained, which may hinder productivity. Even if the amount used is large, the effect of reducing the viscosity is limited in the present embodiment because the amount of natural rubber is small, and it is preferable that the upper limit is about 1.5 PHR.

As the decomposing agent, for example, aromatic mercaptan-based, aromatic disulfide-based, aromatic mercaptan metal salt-based, and the like, which are generally used in the rubber industry, can be used, and they can be used alone. However, two or more types may be used in combination.

Examples of the aromatic mercaptan-based detoxifying agent include xylenethiol, pentachlorothiophenol, β-naphthyl mercaptan, pt-butylthiophenol, t-butyl-o-thiocresol, o-benzamide thiophenol and the like. Can be mentioned. Examples of the aromatic disulfide system include o, o'-dibenzamide diphenyl disulfide, bis (2,4-dimethylphenyl) disulfide and the like. Examples of the aromatic mercaptan metal salt system include the above-mentioned aromatic mercaptan metal salt (zinc salt and the like).

The melting point of the frothing agent is preferably 40 to 160 ° C, more preferably 45 to 150 ° C. If it is less than 40 ° C, blocking may occur when the environmental temperature is high, and if it exceeds 160 ° C, it may not dissolve in the rubber kneading.

(4) Vulcanization chemicals As the vulcanization chemicals, sulfur as a vulcanizing agent and a vulcanization accelerator are appropriately used according to the rubber component. If these vulcanizing chemicals are added in the base kneading step, vulcanization of the rubber may be started due to the high kneading rubber temperature, so they are added in the finishing kneading step.

As the sulfur, powdered sulfur may be used, but in consideration of dispersibility in rubber, it is preferable to use oil-treated powdered sulfur.

As the vulcanization accelerator, a vulcanization accelerator generally used in combination with powdered sulfur in the rubber industry can be used, and specific vulcanization accelerators include, for example, sulfenamide-based, thiazole-based, and thiuram-based. , Thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, or xantate-based vulcanization accelerators, which can be used alone, but two or more. May be used together.

(5) Other compounding materials In this embodiment, in addition to the above-mentioned rubber components and each compounding material, other compounding materials generally used in the rubber industry, such as stearic acid, antioxidants, and zinc oxide. Etc. are appropriately mixed.

2. 2. Production of rubber composition according to the present embodiment In the present embodiment, the rubber composition and each compounding material are put into a closed kneader and kneaded under the above-mentioned specific kneading conditions to obtain a rubber composition. Manufacture. Specifically, in the base kneading process, after kneading to a predetermined rubber temperature, the kneaded rubber is discharged from a closed kneader at a temperature of 150 ° C. or higher, and then passed through a conventional remill kneading process. By entering the finishing kneading step without doing the kneading and kneading at a kneading temperature of 90 to 110 ° C., a sufficient viscosity reducing effect is obtained in a short time. Hereinafter, the process will be described in order.

(1) Base kneading process In the base kneading process, each of the above-mentioned compounding materials other than the vulcanizing chemicals is put into a closed kneader and kneaded. The closed type kneader is not particularly limited, but a Banbury mixer is preferable.

The temperature of the kneaded rubber rises by kneading each of the charged materials. Then, kneading is performed until the temperature of the kneaded rubber rises sufficiently and the temperature of the kneaded rubber when discharged from the closed kneader becomes 150 ° C. or higher, which is higher than the conventional one.

As described above, by kneading at a temperature higher than the conventional one, the viscosity reducing effect of the deliquescent agent can be more efficiently exhibited, and the viscosity can be reduced.

In the present embodiment, it is preferable that the above-mentioned base kneading step is divided into two steps, A and B, and kneaded.

First, a compounding material excluding carbon black and vulcanizing chemicals is put into a closed kneader together with a rubber component, and kneading is performed until the kneading temperature reaches 110 to 130 ° C. (step A). In the step A, since the kneading is performed in a state where the carbon black is not added, the carbon black does not hinder the decoupling reaction during the kneading. As a result, kneading can be performed so as to maximize the effect of the deliquescent agent, and the viscosity of the kneaded rubber is quickly reduced.

Then, carbon black is additionally added and further kneaded until the temperature reaches a predetermined rubber temperature, and the kneaded rubber is discharged from the closed type kneader at a temperature of 150 ° C. or higher (step B). In this step B, the effect of the crushing agent is maximized in the step A, and carbon black is added to the kneaded rubber whose viscosity is sufficiently reduced by kneading, so that the effect in the kneading process can be improved. It can be demonstrated in a short time.

As a result, when kneading is performed at the same discharge temperature and the same base kneading time (total) as in the case of base kneading without dividing into two steps, carbon black is added in a state where the viscosity is sufficiently lowered. In the rubber composition after the base kneading step, the viscosity can be further reduced as compared with the case where the base kneading is performed without dividing into two steps.

On the other hand, since the carbon black is added in a state where the viscosity is sufficiently lowered, in the subsequent step B, the kneading temperature is not raised to the discharge temperature when the base is kneaded without dividing into two steps. Since the viscosity can be the same as that in the case of base kneading without dividing into two steps, the kneading time in step B can be shortened, and the total base kneading time can be further shortened.

At this time, in the present embodiment, the rubber component and the compounding material after the carbon black is added to the closed kneader are charged so that the filling rate of the entire kneader is 60 to 80%. Is preferable. By setting such a filling rate, an appropriate shearing force is applied to the rubber during kneading, which also contributes to the reduction of viscosity.

As described above, by kneading under the above heating conditions, even if the amount of natural rubber is small, the kneaded rubber is provided with the viscosity reducing effect by the shearing force in addition to the viscosity reducing effect by the deliquescent agent. be able to.

In the above, when the kneaded rubber is kneaded so that the temperature of the kneaded rubber at the time of discharge is less than 150 ° C., a sufficient viscosity reducing effect cannot be exhibited, and a remill kneading step is required as in the conventional case. Therefore, workability cannot be improved.

(2) Finish kneading process At the end of the base kneading process, the kneaded rubber discharged from the closed kneader is air-cooled until the temperature of the kneaded rubber reaches 30 to 50 ° C, and then put into the closed kneader again. Further, vulcanizing chemicals are added together and kneaded at a temperature of 90 to 110 ° C.

Then, the kneaded rubber for which the finish kneading has been completed is discharged from the closed type kneader to complete the production of the rubber composition.

A rubber member formed by using the rubber composition thus produced is preferable as a rubber member such as a tread because it has excellent wet grip and cut resistance.

Hereinafter, the present invention will be described in more detail based on Examples.

[1] Experimental Example 1
In this experimental example, carbon black was added at the same time as the rubber component was added, and the effect on the kneading process was confirmed.

1. 1. Rubber compounding The rubber components and compounding materials shown in Table 1 were used in the production of the rubber compositions of Comparative Examples 1 to 6 and Examples 1 to 4.

2. 2. Production of Rubber Composition (1) Base Kneading Step The above-mentioned rubber components and compounding materials were base-kneaded with the formulations shown in Comparative Examples 1 to 6 and Examples 1 to 4 in Table 2.

Specifically, the rubber component and the compounding material other than the vulcanization chemicals (sulfur and vulcanization accelerator) are charged into the Kobe Steel Banbury Mixer BB24011D rotor so that the filling ratio is 72%. The kneaded rubber was kneaded at a rotor rotation speed of 60 rpm until the temperature of the kneaded rubber reached each discharge temperature (base kneading) shown in Table 2, and then the kneaded rubber was discharged from the Banbury mixer.

The obtained kneaded rubber was sent to the remill kneading step in Comparative Examples 1 to 4, kneaded and discharged again in the same manner as in the base kneading step, and then sent to the finishing kneading step. On the other hand, in Comparative Examples 5 and 6 and Examples 1 to 4, the remill kneading step was not performed and the process was sent to the finishing kneading step as it was.

(2) Finishing kneading step The kneaded rubber obtained above is air-cooled to 30 to 50 ° C., and then put into a closed kneader again, and sulfur and a vulcanization accelerator of vulcanization chemicals are put into it. Then, the kneaded rubber was kneaded at a rotor rotation speed of 30 rpm until the temperature of the kneaded rubber reached each discharge temperature (finish kneading) shown in Table 2, and then the kneaded rubber was discharged from the Banbury mixer to obtain each rubber composition.

(3) Kneading time In each of the above Examples and Comparative Examples, the time from the start to the end of kneading (kneading time) was set as shown in Table 2. In Table 2, it is shown by an index with Comparative Example 1 as 100, and the larger the value, the longer the total kneading time.

3. 3. Evaluation of Viscosity Each rubber composition obtained was cut out to a size of (length) 4 cm x (width) 4 cm x (thickness) 7-9 mm, and was used under the conditions of 130 ° C. using a Mooney Viscometer SMV-202 manufactured by Shimadzu Corporation. The rubber composition was preheated for 1 minute from the start of the measurement, and then the viscosity of the rubber composition was measured after 4 minutes had passed.

For the evaluation, each measurement result was evaluated as an index with Comparative Example 1 as 100. The larger the value, the higher the viscosity. The results are shown in Table 2.

From the results shown in Table 2, first, from Comparative Example 1 and Comparative Example 6 having the same composition without using a frothing agent, when the remill kneading step is omitted, the kneading time can be shortened, but the viscosity of the rubber composition is high. It turns out that it rises on the contrary.

Further, even in Comparative Examples 4 and 5 having the same composition using 0.5 PHR of the decoction agent, when the remill kneading step is omitted, the kneading time can be shortened, but the viscosity of the rubber composition is rather increased. There is. On the other hand, when the discharge temperature of the kneaded rubber in the base kneading step is raised as in Example 1, the kneading time is shortened by omitting the remill kneading step by using 0.5 PHR of the crushing agent. It can also be seen that the viscosity of the rubber composition is reduced.

Further, in each example, it can be seen that by omitting the remill kneading step, the rubber viscosity is sufficiently reduced even though the kneading is performed in a shorter time of 70% as compared with Comparative Example 1.

[2] Experimental Example 2
In this experimental example, the base kneading step is divided into the above-mentioned two steps, A step and B step, and carbon black is added in the B step. It was investigated whether the effect on the kneading process changed to some extent.

1. 1. Rubber compounding In producing the rubber compositions of Examples 5 to 12, the rubber components and compounding materials shown in Table 1 were used in the same manner as in Experimental Example 1 above.

2. 2. Production of Rubber Composition (1) Base Kneading Step The above-mentioned rubber components and compounding materials were base-kneaded with the formulations shown in Examples 5 to 12 in Table 3.

Specifically, in step A, a compounding material excluding carbon black and vulcanization chemicals (sulfur and vulcanization accelerator) is added together with the rubber component and kneaded until the kneading temperature reaches 110 ° C. to carbon black. Was charged in step B, and kneaded in the same manner as in Examples 1 to 4 except that the kneading temperature, that is, the final reached temperature in step B was set to 160 ° C., and kneaded rubber was added. Ejected from the rubbery mixer.

(2) Finish-kneading step Using the obtained kneaded rubber, finish-kneading was performed in the same manner as in Examples 1 to 4, and the kneaded rubber was discharged from the Banbury mixer to obtain each rubber composition.

(3) Kneading time The time from the start to the end of kneading (kneading time) in each example is as shown in Table 3. In Table 3, the index is shown with Example 1 in Experimental Example 1 as 100.

3. 3. Evaluation of Viscosity In the same manner as in Experimental Example 1, the viscosity of the rubber composition of each Experimental Example was measured and evaluated by an index with Example 1 in Experimental Example 1 as 100. The results are shown in Table 3 together with the results of Examples 1 to 4.

From the results shown in Table 3, the base kneading process was divided into two, and the discharge temperature and the total kneading time were the same as in Examples 1 to 4 (base kneading without dividing into two processes) (Example 5). 8), it can be seen that the viscosity of the rubber composition is further reduced as compared with Examples 1 to 4.

On the other hand, when the base kneading process is divided into two and the discharge temperature from the base kneading process is lower than that of Examples 1 to 4 (Examples 9 to 12), the kneading time is shorter than that of Examples 1 to 4. It can be seen that a certain degree of viscosity of the rubber composition is obtained.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. It is possible to make various modifications to the above embodiments within the same and equal range as the present invention.

Claims (9)

A sealed type containing 100 PHR, a rubber component composed of natural rubber of 40 PHR or less and synthetic rubber of 60 PHR or more, carbon black 30 PHR to 100 PHR, a deliquescent agent of 0.3 PHR or more, and a predetermined amount of vulcanizing chemicals. A method for producing a rubber composition, which is a method for producing a rubber composition by kneading using a kneader.
The rubber component and the compounding material excluding the vulcanizing chemical from the compounding material were simultaneously put into the closed kneader and kneaded until the predetermined rubber temperature was reached, and then the kneaded rubber was kneaded at 150 ° C. The base kneading process of discharging from the closed type kneader at the above temperature and
It is provided with a finish kneading step in which the entire amount of rubber obtained in the base kneading step is charged into a closed kneader, and the vulcanizing chemicals are charged and kneaded at a kneading temperature of 90 to 110 ° C. A method for producing a characteristic rubber composition. The base kneading process
A step of putting the compounding material excluding the carbon black and the vulcanizing chemical together with the rubber component into the closed kneader and kneading until the kneading temperature reaches 110 to 130 ° C.
It is characterized by comprising a step of additionally adding the carbon black, further kneading it until it reaches a predetermined rubber temperature, and discharging the kneaded rubber from the closed type kneader at a temperature of 150 ° C. or higher. The method for producing a rubber composition according to claim 1 . The method for producing a rubber composition according to claim 1 or 2, wherein the synthetic rubber is styrene-butadiene rubber. The method for producing a rubber composition according to claim 3, wherein the styrene-butadiene rubber is an emulsion-polymerized styrene-butadiene rubber. The method for producing a rubber composition according to any one of claims 1 to 4, wherein the closed-type kneader is a Banbury mixer. The method for producing a rubber composition according to any one of claims 1 to 5, wherein the filling rate of the rubber component and the compounding material in the closed kneader is 60 to 80%. .. Air using the rubber composition produced by the method for producing a rubber composition according to any one of claims 1 to 6 to form a rubber member for a pneumatic tire. A method for manufacturing rubber members for tires. The method for manufacturing a rubber member for a pneumatic tire according to claim 7, wherein the rubber member for a pneumatic tire is a tread rubber. A method for manufacturing a pneumatic tire, which comprises manufacturing a pneumatic tire using the rubber member for a pneumatic tire manufactured by the method for manufacturing a rubber member for a pneumatic tire according to claim 7 or 8.