JP2000280236A - Production of unvulcanized rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an unvulcanized rubber composition in which labor saving, space saving, energy saving and cost reduction are contrived. SOLUTION: The following all processes are performed in the same rubber kneader, namely, a raw material rubber charging process of charging the raw material rubber not containing a rubber compounding ingredient into a rubber kneader, a mastication process of independently kneading the raw material rubber in the rubber kneader, a rubber compounding ingredient charging process of charging the rubber compounding ingredient excepting a vulcanizing agent to the masticated raw material rubber, a mixing and kneading process of mixing the masticated raw material rubber with the rubber compounding ingredient excepting the vulcanizing agent by the rubber kneader, a cooling process of lowering the temperature of mixed and kneaded rubber composition, a vulcanizing agent charging process of charging the vulcanizing agent to the cooled, mixed and kneaded rubber composition and a vulcanizing agent mixing process of mixing the cooled, mixed and kneaded rubber composition with the vulcanizing agent by the rubber kneader.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an unvulcanized rubber composition used for processing rubber products.

[0002]

2. Description of the Related Art An unvulcanized rubber composition generally used for processing rubber products is manufactured through the following three rubber kneading steps (where "step" is a rubber kneading machine). It means the concept including charging, rubber kneading, and taking out the kneaded rubber from the rubber kneading machine.

[0003] First, a raw rubber containing no rubber compound is kneaded by a rubber kneader alone. This rubber kneading step is called a mastication step, in which the molecular chains of the raw rubber are cut, and the lengths of the molecular chains are averaged. In addition, the elasticity of the raw rubber is reduced and the plasticization is increased, so that the subsequent rubber kneading workability is improved. Second, a rubber compounding agent such as carbon black, a plasticizer (oil), stearic acid, an antioxidant, etc. is added to the raw rubber after mastication, and the whole is kneaded with a rubber kneading machine. This rubber kneading step is called a kneading step. By mixing these rubber compounding agents with the raw rubber, the strength of the rubber product after vulcanization is increased, the kneading processability of the rubber is improved, and the rubber molecular chain is formed. Effects such as prevention of rubber deterioration due to radicals generated by the cutting are obtained. Third, a required amount of a vulcanizing agent is added to the kneaded rubber compound and the whole is kneaded. This rubber kneading step is called a vulcanizing agent mixing step. The vulcanizing agent reacts with the rubber molecules to form a bridge structure between the rubber molecules to form a three-dimensional network of the molecules, thereby providing rubber elasticity.

[0004] These three rubber kneading steps are not performed continuously, but are performed intermittently and using a plurality of types of rubber kneading machines. For example, there is a case where after kneading is performed by a Banbury mixer, kneading is performed by a kneader, and vulcanizing agent mixing is performed by a roll mixer.

[0005]

However, the conventional method for producing unvulcanized rubber in which each rubber kneading step is separately independent has the following problems.

[0006] First, since the same operation associated with rubber kneading, such as charging and removing rubber, is repeatedly performed for each rubber kneading step, there is a problem that the efficiency of the entire rubber kneading step is poor.

Further, in each rubber kneading step, heat is applied to the rubber in order to improve the rubber kneading processability. However, when each rubber kneading step is performed intermittently, the rubber is kneaded once in the mastication step. Even if the temperature rises, the rubber cools down in the process of transferring the rubber from the kneading rubber kneader to the kneading rubber kneader, and it is necessary to apply heat to the rubber again in the kneading step. Similarly, even if the temperature of the rubber once rises in the kneading step, the temperature of the rubber may drop unnecessarily in the stage of the vulcanizing agent mixing step, in which case it is necessary to apply heat to the rubber again. . Therefore, there is a disadvantage that wasteful energy is consumed for raising the temperature of the rubber as a whole rubber kneading step.

Further, when a different rubber kneading machine is used for each rubber kneading step, there is a problem that it is necessary to secure a space for installing a plurality of types of rubber kneading machines in a factory.

Further, as described above, the work efficiency of the rubber kneading step is low and energy is wasted, so that the cost required for producing unvulcanized rubber increases.

[0010] The present invention has been made in view of the above points, and an object of the present invention is to continuously perform three rubber kneading steps of mastication, kneading, and vulcanizing agent mixing by one rubber kneading step. The purpose of the present invention is to achieve labor saving, space saving, energy saving, and cost reduction in the production of unvulcanized rubber by using a machine.

[0011]

According to the present invention, in a method for producing an unvulcanized rubber, three kneading steps of mastication, kneading and mixing of a vulcanizing agent are continuously performed by one rubber kneading machine. It is what it was.

Specifically, the invention according to claim 1 is a method for producing an unvulcanized rubber composition used for processing rubber products, wherein a raw rubber containing no rubber compounding agent is fed to a rubber kneading machine. A raw rubber charging step of charging, a masticating step of kneading the raw rubber with the rubber kneading machine, and a rubber compounding agent charging of a rubber compounding agent excluding a vulcanizing agent to the masticated raw rubber in the rubber kneading machine A kneading step of mixing the kneaded raw rubber and the rubber compounding agent with the rubber kneading machine, a cooling step of lowering the temperature of the kneaded rubber composition in the rubber kneading machine, and the rubber A vulcanizing agent charging step of charging a vulcanizing agent to the cooled kneaded rubber composition in a kneading machine, and mixing the cooled kneaded rubber composition and the vulcanizing agent with the rubber kneading machine Vulcanizing agent mixing step All steps are the production method of the unvulcanized rubber composition characterized by being carried out in the same rubber kneading machine.

In the above method for producing an unvulcanized rubber composition, charging of raw rubber containing no rubber compounding agent, mastication, charging of rubber compounding agent excluding vulcanizing agent, kneading, cooling, vulcanizing agent charging. Since the steps of mixing the vulcanizing agent and the vulcanizing agent are continuously performed in one rubber kneading machine, it is not necessary to carry out the loading and unloading of rubber at each rubber kneading step.
Therefore, rationalization and labor saving of the rubber kneading operation can be achieved.

After the mastication step, the rubber compounding agent excluding the vulcanizing agent is charged, and then the process proceeds to the kneading step. After the kneading step, the rubber is cooled and the vulcanizing agent is charged, followed by the vulcanizing agent. Move to mixing. That is, the rubber moves to the kneading step or the vulcanizing agent mixing step when the temperature has risen to some extent, and there is no need for heating for compensating for the decrease in temperature as in the conventional case. Therefore, energy saving can be achieved as a whole rubber kneading step.

Furthermore, since a single rubber kneading machine can perform from the introduction of the raw rubber containing no rubber compounding agent to the mixing of the vulcanizing agent, there is no need to install a plurality of types of rubber kneading machines, and the space of the factory can be saved. Can be achieved.

[0016] The cost of the entire rubber kneading step can be reduced due to the rationalization, labor saving, and energy saving of the rubber kneading step.

If the heat generated by the deformation of the rubber is large in the vulcanizing agent mixing step, the vulcanization of the rubber proceeds in this step.

Further, even when the time of the vulcanizing agent mixing step is prolonged, the rubber is given a temperature history at a high temperature, which causes the vulcanization of the rubber to proceed. Therefore, it is preferable that the mixing of the vulcanizing agent can be performed in as short a time as possible.

Further, as rubber types to which the method of producing the unvulcanized rubber composition can be applied, natural rubber, chloroprene rubber (CR), nitrile rubber (NBR), acrylic rubber (ACM), ethylene-propylene rubber (EPDM) ), A mixture of two or more rubbers, and a mixture of rubber and another polymer, but from the viewpoint of preventing the progress of vulcanization of the rubber in the above vulcanizing agent mixing step. From, natural rubber with low specific heat and easy to cool,
The application to chloroprene rubber (CR) and nitrile rubber (NBR) is particularly preferred.

In the raw rubber charging step, the raw rubber may be charged while the rotor of the rubber kneading machine is stopped. However, a high torque is required when the rotor is driven, which may cause a failure of the rubber kneading machine. Therefore, it is preferable to feed the raw rubber while rotating the rotor of the rubber kneading machine.

The temperature of the rubber in the mastication step is preferably 130 ± 20 ° C. from the viewpoint of balancing the kneading processability of the rubber and the prevention of thermal deterioration of the rubber.

In the compounding agent charging step, the rubber compounding agent may be charged while the rotor of the rubber kneading machine is stopped. It is preferable that the rubber compounding agent is charged while the rubber is continuously kneaded.

The temperature of the rubber in the kneading step is preferably 130 ± 20 ° C. from the viewpoint of balancing the kneading processability of the rubber and the prevention of thermal deterioration of the rubber, as in the case of the mastication step.

In the cooling step, after the kneading step, the rubber of the rubber kneading machine may be cooled by stopping the rotation of the rotor of the rubber kneading machine. However, in order to rapidly lower the temperature of the whole rubber, the rotor of the rubber kneading machine is required. It is preferable to cool the rubber while rotating at a low speed. After the rubber composition has been homogenized at the end of the kneading step, cooling of the rubber may be started while rotating the rubber kneading machine.

In the vulcanizing agent introduction step, the vulcanizing agent may be introduced by stopping the rotor of the rubber kneading machine. However, in order to quickly disperse the vulcanizing agent in the rubber, the rotor of the rubber kneading machine must be operated. It is preferable to feed the vulcanizing agent while rotating.

The temperature of the rubber in the vulcanizing agent mixing step is preferably 95 ± 10 ° C. from the viewpoint of balancing the kneading processability of the rubber and the progress of vulcanization of the rubber.

According to a second aspect of the present invention, there is provided the method for producing an unvulcanized rubber composition according to the first aspect, wherein the rubber kneading machine is an intermeshing mixer. It is a manufacturing method.

In the method for producing such an unvulcanized rubber composition, the rubber kneading machine is a meshing mixer excellent in cooling efficiency. Therefore, the cooling of the rubber at the time of shifting from the kneading step to the vulcanizing agent mixing step is quickly performed,
In the vulcanizing agent mixing step, the progress of vulcanization of the rubber can be effectively prevented. Here, the intermeshing mixer refers to an intermeshing Banbury mixer or an intermeshing kneader.

According to a third aspect of the present invention, there is provided the method for producing an unvulcanized rubber composition according to the first or second aspect, wherein in the raw rubber charging step, the raw rubber containing no rubber compounding agent is shredded. A method for producing an unvulcanized rubber composition, which comprises introducing an agent into a rubber kneading machine and masticating a raw rubber containing no rubber compounding agent together with a shredder in a mastication step.

In the method for producing the unvulcanized rubber composition, the raw rubber is masticated together with the shredder,
The viscosity of the raw rubber decreases, and mastication processability can be improved. Accordingly, the raw rubber is uniformly masticated as a whole, and a masticated rubber having no variation in quality can be obtained. In addition, di- (benzamidophenyl) disulfide and the like are used as shuffling agents. The shattering agent is added for the purpose of lowering the viscosity of the raw rubber, and is different from the rubber compounding agent.

[0031]

As described above, according to the first aspect of the present invention, charging of raw rubber containing no rubber compounding agent, mastication, charging of rubber compounding agent excluding vulcanizing agent, kneading and cooling. ,
Since the steps of charging the vulcanizing agent and removing the vulcanizing agent mixing are performed continuously in one rubber kneading machine, the rubber kneading step can be rationalized and labor-saving. In addition, since heating for compensating for a decrease in the temperature of rubber as in the related art is not required in the kneading step and the vulcanizing agent mixing step, energy saving can be achieved in the entire rubber kneading step. In addition, since one rubber kneading machine can perform everything from the charging of raw rubber containing no rubber compounding agent to the mixing of vulcanizing agents, there is no need to install multiple types of rubber kneading machines, thus saving space in factories. Can be. Since the labor saving and rationalization and energy saving of the rubber kneading step are achieved, the cost of the entire rubber kneading step can be reduced.

According to the second aspect of the present invention, in addition to the effect of the first aspect, since the rubber kneading machine is an intermeshing mixer, the kneaded rubber can be cooled quickly. In addition, the progress of vulcanization of the rubber in the vulcanizing agent mixing step can be effectively prevented.

Further, according to the third aspect of the invention, in addition to the effects of the second or third aspect, the raw rubber is masticated together with the shattering agent, so that the processability of the mastication is improved. The quality of the masticated rubber can be stabilized.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing an unvulcanized rubber using an intermeshing type kneader will be described in detail with reference to the drawings as an embodiment of the present invention.

<Intermeshing Kneader> FIG. 1 shows a cross section of a rubber kneading portion of an intermeshing kneader used in the method for producing an unvulcanized rubber composition of the present invention. The rubber kneading part of the meshing type kneader includes a pair of rotors 1a and 1b and a mixing tank 2
And a pressure cylinder 3.

The pair of rotors 1a and 1b are installed in the mixing tank 2 in parallel. And each rotor 1a, 1b
When rubber is placed on the upper part between the rotors 1a and 1b, the rubbers rotate in directions opposite to each other in a direction to push the rubber downward. Further, the trajectory of the blade of the rotor 1a and the trajectory of the blade of the rotor 1b have an overlapping portion near the center between the axes of the respective rotors 1a and 1b. However, the rotors 1a and 1b always form a gap between them, and rotate without contacting each other. When the rubber passes through the gap, shear deformation is applied to the rubber, and the rubber is kneaded.

The mixing tank 2 surrounds the rotors 1a and 1b, and rubber is kneaded inside the mixing tank 2. Also,
When the rubber passes through the gap between the inner wall of the mixing tank 2 and the rotors 1a and 1b, shear deformation is applied to the rubber, and the rubber is kneaded. The mixing tank 2 is provided with a temperature sensor 21 for sensing the temperature of the rubber.

The pressurizing cylinder 3 serves as a lid of the mixing tank 2. When the pressurizing cylinder 3 rises and the mixing tank 2 is opened, the opening is made of raw rubber, a rubber compounding agent,
It serves as an inlet for the vulcanizing agent and an outlet for the kneaded unvulcanized rubber composition. When the pressure cylinder 3 descends and closes, the opening of the mixing tank 2 is closed, and the rubber compounding agent and the like are scattered. Play a role in preventing.

The temperature inside the rubber kneading section of the meshing kneader is adjusted by passing water whose temperature has been adjusted according to the mixing ratio of steam and cooling water into the rotors 1a and 1b, the mixing tank 2, and the pressurizing cylinder 3. This is done by flowing into a channel.

FIG. 2 is a diagram showing a control mechanism of the meshing type kneader. A temperature sensor 21 is attached to the mixing tank 2 in the rubber kneading section, and detects the temperature of the rubber kneaded. Subsequently, it is converted to an electrical signal and input to the control device. <Rubber Kneading Step> FIG. 3 shows a process sequence in a method for producing an unvulcanized rubber composition.

First, a raw rubber charging step is performed. In this step, the pressurizing cylinder 3 is raised, the mixing tank 2 is opened, and raw rubber containing no rubber compounding agent is introduced from the opening of the mixing tank 2 while rotating the rotors 1a and 1b. At this time, a shattering agent is added together with the raw rubber in order to lower the viscosity of the raw rubber and improve the mastication processability.

Next, the mastication step is performed. In this step,
Lower the pressurizing cylinder 3, close the opening of the mixing tank 2,
The raw rubber is kneaded by the rotation of the rotors 1a and 1b. The molecular chains of the raw rubber are cut by mastication, and the lengths of the molecular chains are averaged. In addition, the elasticity of the raw rubber is reduced and the plasticization is enhanced, so that the subsequent rubber kneading workability is improved. In addition, the temperature sensor 21 attached to the mixing tank 2 detects the temperature of the rubber, which is converted into an electric signal and sent to the control device. Then, a signal is output to the PID controller based on the signal, and the valve connecting the cooling water and the steam is controlled.

Subsequently, a rubber compounding agent charging step is performed. In this step, the pressurizing cylinder 3 is raised, the mixing tank 2 is opened, and a rubber compounding agent excluding a vulcanizing agent such as carbon black, stearic acid, an antioxidant, etc. is charged from the opening of the mixing tank 2. The rubber compounding agent was charged into the rotor 1a,
1b is rotated.

Next, the kneading step is performed. In this step,
Lower the pressurizing cylinder 3, close the opening of the mixing tank 2,
By the rotation of the rotors 1a and 1b, the kneaded raw rubber and the charged rubber compounding agent are kneaded. By mixing the rubber compounding agent with the rubber, the strength of the rubber product after vulcanization is increased, the kneading processability of the rubber is improved, and the deterioration of the rubber due to radicals generated by cutting the rubber molecular chain is prevented. And the like. In addition, the temperature sensor 21 attached to the mixing tank 2 detects the temperature of the rubber, which is converted into an electric signal and sent to the control device. Then, a signal is output to the PID controller based on the signal, and the valve connecting the cooling water and the steam is controlled. In this regard,
The same control as in the mastication step is performed.

Subsequently, a cooling step is performed. In this step,
The pressure cylinder 3 is raised, the mixing tank 2 is opened, and the temperature of the water passing through the water passage is lowered to lower the temperature of the rubber. This is to prevent the vulcanization of the rubber from proceeding in the vulcanizing agent mixing stage after the vulcanizing agent is introduced. Here, the temperature of the water passing through the water passage is controlled by the PID from the control device.
A signal is sent to the controller, which controls the valve and regulates the ratio of cooling water to steam. In addition,
Cooling the rubber while rotating the rotors 1a and 1b at a low speed is efficient because the entire rubber is cooled uniformly.

Next, a vulcanizing agent charging step is performed. In this step, a vulcanizing agent is introduced from the opening of the mixing tank 2. The vulcanizing agent is charged while the rotors 1a and 1b are rotated.

Then, it is a vulcanizing agent mixing step. In this step, the pressure cylinder 3 is lowered, the opening of the mixing tank 2 is closed, and the kneaded rubber and the added vulcanizing agent are kneaded by rotation of the rotors 1a and 1b. The vulcanizing agent reacts with rubber molecules at a high temperature to form a bridge structure between the rubber molecules to form a three-dimensional network of the molecules, and to impart rubber elasticity to the rubber composition after vulcanization. In addition, the temperature sensor 21 attached to the mixing tank 2 detects the temperature of the rubber, which is converted into an electric signal and sent to the control device. Then, a signal is output to the PID controller based on the signal, and the valve connecting the cooling water and the steam is controlled. In this regard, the same control as in the kneading step and the kneading step is performed.

An unvulcanized rubber composition is produced by performing the above series of steps in a single intermeshing kneader.

Next, the operation and effect of the method for producing an unvulcanized rubber composition according to the present embodiment will be described.

In the method for producing the unvulcanized rubber composition according to the present embodiment, the raw rubber containing no rubber compounding agent is charged and masticated, and the rubber compounding agent excluding the vulcanizing agent is charged, kneaded, cooled and vulcanized. Since the steps of adding the sulfuric acid and mixing the vulcanizing agent are continuously performed in a single intermeshing type kneader, it is not necessary to perform the loading and unloading of the rubber at each rubber kneading step. Therefore, rationalization and labor saving of the rubber kneading step can be achieved.

After the mastication step, the rubber compounding agent excluding the vulcanizing agent is charged, and the process is then shifted to the kneading step. After the kneading step, the rubber is cooled and the vulcanizing agent is charged. Move to mixing. That is, the rubber moves to the kneading step or the vulcanizing agent mixing step when the temperature has risen to some extent, and heating for compensating for the decrease in temperature as in the conventional case is not necessary. Therefore, energy saving can be achieved as a whole rubber kneading step.

Furthermore, since a single intermeshing kneader can perform from the introduction of the raw rubber containing no rubber compounding agent to the mixing of the vulcanizing agent, there is no need to install a plurality of types of rubber kneading machines, and the space of the factory can be saved. Can be achieved.

Further, the cost can be reduced as a whole rubber kneading step due to the rationalization, labor saving, and energy saving of the rubber kneading step.

Further, since an intermeshing kneader having a high cooling efficiency is used as the rubber kneading machine, the rubber can be cooled quickly in the transition from the kneading step to the vulcanizing agent mixing step, and the vulcanizing agent mixing step can be performed. In this case, the progress of vulcanization of the rubber can be effectively prevented.

Then, the smashing agent is added together with the raw rubber and masticated, so that the viscosity of the raw rubber decreases,
The mastication processability of the raw rubber can be improved. Accordingly, the raw rubber is uniformly masticated as a whole, and a masticated rubber having no variation in quality can be obtained.

<Application Example 1 of the Present Invention> An example in which the above-described unvulcanized rubber production method is applied to natural rubber will be described. The rubber compounding is as shown in Table 1.
Is a unit that represents parts by weight of each rubber compounding agent to be added to 100 parts by weight of the raw rubber. )

[0057]

[Table 1]

The raw rubber containing no compounding agent is natural rubber. The rubber compounding agent excluding the vulcanizing agent is a plasticizer, FEF carbon black, calcium carbonate, zinc oxide, stearic acid, wax, an antioxidant and a vulcanization accelerator. And the vulcanizing agent is sulfur.

FIG. 4 shows a process chart of application example 1 of the present invention.
In the figure, the horizontal direction indicates the passage of time. The upper flat portion in the vertical direction indicates a state in which the mixing tank 2 of the meshing kneader is closed, that is, a state in which the pressure cylinder is lowered, and the lower flat portion indicates a state in which the mixing tank 2 is open. That is, it shows a state in which the pressure cylinder is raised.

First, the meshing kneader rotors 1a, 1
b was rotated, and 0.3 phr of natural rubber and di- (benzamidophenyl) disulfide as a shuffling agent were charged from the opening of the mixing tank 2. And pressurizing cylinder 3
And natural rubber was masticated. At this time, rotor 1
The rotation speeds a and 1b were set at 40 rpm, and the temperature of the water flowing through the water passage was set at 60 ° C. The mastication was performed for 120 seconds, and the temperature of the rubber at the end of the mastication was 125 ° C.

Next, the pressure cylinder 3 was raised while rotating the rotors 1 a and 1 b at 40 rpm, and a rubber compounding agent excluding the vulcanizing agent was introduced from the opening of the mixing tank 2. The pressure cylinder is lowered again, and the rotation speed of the rotors 1a and 1b is reduced to 40 rpm.
The kneading was carried out while keeping at m. The kneading was performed for 100 seconds, and the temperature of the rubber at the end of the kneading was 125 ° C. The temperature of the water flowing through the water passage was set at 60 ° C. until 60 seconds after the start of kneading, and thereafter, the temperature was changed to 25 ° C.

Subsequently, the pressure cylinder 3 was raised, and the rotation speed of the rotors 1a and 1b was reduced to 5 rpm to cool the rubber. The cooling was performed for 150 seconds, and the temperature of the rubber at the end of cooling was 90 ° C.

Next, sulfur was introduced from the opening of the mixing tank 2, the pressure cylinder 3 was lowered again, and the rotation speed of the rotors 1a and 1b was set at 20 rpm to mix the vulcanizing agent. Mixing of the vulcanizing agent was performed for 60 seconds. Forty seconds after the start of mixing, the operation of raising the pressurizing cylinder 3 once and immediately lowering it was performed. At this time, the rubber exhibited a behavior in which the rubber once rises together with the pressurizing cylinder 3 and is pulled back downward by the rotors 1a and 1b. In this way, by temporarily stopping the steady kneading state and shifting to another steady kneading state, the dispersibility of the rubber compounding agent including sulfur can be improved.

Finally, the kneaded unvulcanized natural rubber composition was taken out of the mixing tank 2. At this time, the temperature of the rubber is 95
° C.

<Application Example 2 of the Present Invention> The above method for producing an unvulcanized rubber is performed by using nitrile rubber (NBR) and vinyl chloride (PV).
An example applied to the mixture of C) will be described. The rubber composition is as shown in Table 2.

[0066]

[Table 2]

The raw rubber containing no compounding agent is a mixture of nitrile rubber (NBR) and vinyl chloride (PVC). The rubber compounding agent excluding the vulcanizing agent is a liquid nitrile rubber, FEF carbon black, silica, zinc oxide, stearic acid, an antioxidant, and a vulcanization accelerator. And the vulcanizing agent is sulfur.

FIG. 5 shows a process chart of application example 2 of the present invention.
The contents of the figure are the same as those in FIG.

First, the meshing kneader rotors 1a, 1
b, the nitrile rubber (N
(BR) and vinyl chloride (PVC). Then, lower the pressure cylinder 3 and use nitrile rubber (NBR).
And a mixture of vinyl chloride (PVC) were masticated. At this time, the rotation speed of the rotors 1a and 1b was set at 30 rpm, and the water flowing through the water passage was set at 60 ° C. The mastication is done for 50 seconds,
The rubber temperature at the end of mastication was 140 ° C.

Next, the pressurizing cylinder 3 is raised and the rotor 1
The rubber compounding agent excluding the vulcanizing agent was charged from the opening while rotating at a setting of a and 1b at 40 rpm. The pressure cylinder is lowered again, and the number of rotations of the rotors 1a and 1b is increased to 4
Kneading was performed while keeping the rotation at 0 rpm. The kneading was performed for 120 seconds, and the temperature of the rubber at the end of the kneading was 135 ° C. The temperature of the water flowing through the water passage is set at 8 after the start of kneading.
The temperature was set at 60 ° C until 0 seconds, but after that, 25 ° C was set.
° C.

Subsequently, the pressure cylinder 3 was raised, and the rotation speed of the rotors 1a and 1b was reduced to 5 rpm to cool the rubber. Cooling was performed for 150 seconds, and the temperature of the rubber at the end of cooling was 100 ° C.

Next, sulfur was introduced from the opening of the mixing tank 2 and the pressure 1 cylinder 14 was lowered again.
The vulcanizing agent was mixed at a rotation speed of 20 rpm of b. Mixing of the vulcanizing agent was performed for 60 seconds. Forty seconds after the start of mixing, the operation of raising the pressurizing cylinder 3 once and immediately lowering it was performed. At this time, the rubber exhibited a behavior in which the rubber once rises upward together with the pressurizing cylinder 3 and is pulled back downward by the rotors 1a and 1b.

Finally, the kneaded unvulcanized natural rubber composition was taken out of the mixing tank 2. At this time, the temperature of the rubber is 95
° C.

[0074]

[Other Embodiments] In the above embodiment, a meshing kneader is used as a rubber kneading machine.
It is not particularly limited to this, but a roll mixer,
It may be a Banbury mixer or the like.

As an application example of the present invention, an example of natural rubber and an example of a mixture of nitrile rubber and vinyl chloride have been described.
The method for producing the unvulcanized rubber composition according to the present invention is not particularly limited to these rubber types, but may be used alone such as chloroprene rubber (CR), acrylic rubber (ACM), ethylene-propylene rubber (EPDM) and the like. The present invention can be applied to a kind of rubber, a mixture of two or more kinds of rubber, a mixture of rubber and another polymer, and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a rubber kneading portion of a meshing type kneader.

FIG. 2 is a diagram illustrating a control mechanism of a meshing kneader.

FIG. 3 is a view showing a process sequence in a method for producing an unvulcanized rubber composition according to the present invention.

FIG. 4 is a process chart of application example 1 of the present invention.

FIG. 5 is a process chart of application example 2 of the present invention.

[Explanation of symbols]

 1a rotor 1b rotor 2 mixing tank 3 pressurized cylinder 21 temperature sensor

Claims (3)

[Claims] 1. A method for producing an unvulcanized rubber composition used for processing a rubber product, comprising: a raw rubber charging step of charging a raw rubber not containing a rubber compounding agent into a rubber kneading machine; A mastication step of kneading with the rubber kneading machine, a rubber compounding agent charging step of charging a rubber compounding agent excluding a vulcanizing agent to the masticated raw rubber in the rubber kneading machine, A kneading step of mixing a rubber compounding agent with the rubber kneading machine; a cooling step of lowering the temperature of the kneaded rubber composition in the rubber kneading machine; and the cooled kneaded rubber in the rubber kneading machine. A vulcanizing agent charging step of charging a vulcanizing agent to the composition; and a vulcanizing agent mixing step of mixing the cooled kneaded rubber composition and the vulcanizing agent with the rubber kneading machine. All processes are the same rubber kneading Method for producing unvulcanized rubber composition characterized by being carried out in the machine. 2. The method for producing an unvulcanized rubber composition according to claim 1, wherein the rubber kneading machine is an intermeshing mixer. 3. The method for producing an unvulcanized rubber composition according to claim 1 or 2, wherein in the raw rubber charging step, the shredder together with the raw rubber containing no rubber compounding agent is fed to a rubber kneader. A method for producing an unvulcanized rubber composition, comprising: in a mastication step, masticating a raw rubber containing no rubber compounding agent together with a shredder.