JP6906752B2 - Rubber strip manufacturing method and manufacturing equipment - Google Patents

Description

The present invention relates to a method and an apparatus for manufacturing a rubber strip used for manufacturing a pneumatic tire or the like.

As one of the methods for manufacturing a pneumatic tire, there is a strip wind method in which a narrow band-shaped rubber strip is spirally wound on a molding drum to form a raw cover. This rubber strip is obtained by continuously extruding a kneaded rubber composition from a rubber extrusion means in a rubber extrusion step to preform it to a predetermined width and thickness, and further rolling it in a rolling step using a rolling means such as a calendar roll. It is manufactured by molding into a predetermined shape (see, for example, Patent Document 1). Then, the manufactured rubber strip is taken up to the forming drum and wound to form a low cover.

At this time, in the rolling process, the rubber strip in close contact with the calendar roll may have to be forcibly peeled off in order to release the mold. Such forced peeling of the rubber strip causes shrinkage of the rubber strip after molding, and greatly deforms the cross-sectional shape of the rubber strip. Further, if the adhesive force (tack) exceeds the strength of the rubber waist (hereinafter, also referred to as "overadhesion"), the rubber strip may be cut at the time of peeling and cannot be removed.

On the other hand, in recent years, studless tires are often used for icy road surfaces for environmental protection. In addition, from the viewpoint of safety, winter tires other than studless tires and all-season tires are also required to have higher grip performance, and in order to obtain such high grip performance, treads are required. There is a growing tendency for rubber compositions containing a large amount of softeners such as oil to be used.

However, since rubber compositions containing a large amount of softeners such as oil have high adhesiveness, the importance of releasability from a calendar roll during the production of rubber strips is becoming more and more important.

Here, it is known that the tack of the rubber composition on the calendar roll is affected not only by the adhesiveness of the rubber composition but also by the temperature of the calendar roll. For this reason, conventionally, by optimizing the temperature of the calendar roll by using various methods, releasability has been ensured even in a highly adhesive rubber composition. However, in recent years, a wide variety of rubber compositions have been used depending on the application, such as for passenger cars, motorcycles, and heavy loads, and the appropriate temperature for releasing from the calendar roll differs for each rubber composition. Therefore, it cannot be said that it is easy to deal with it by the conventional technology.

Therefore, as a technique capable of coping with such diversification of rubber compositions, each rubber composition is formed by setting an appropriate temperature in advance according to the rubber composition and controlling the surface temperature of the calendar roll to this appropriate temperature. A technique for ensuring releasability of an object has been developed (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2009-184152 Japanese Unexamined Patent Publication No. 2013-252668

However, since the appropriate temperature of each of the above rubber compositions is usually set by trial and error, it takes a lot of time and labor to set the appropriate temperature of one type of rubber composition, much less various kinds. It took an enormous amount of time and effort to set an appropriate temperature for each of the rubber compositions.

Therefore, according to the present invention, it is possible to set an appropriate rolling temperature for each of a wide variety of rubber compositions without spending a lot of time and labor, and it is possible to stably produce a rubber strip having a predetermined shape. The subject is to provide strip manufacturing technology.

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
A method for manufacturing a rubber strip using a rolling means for forming a narrow band-shaped rubber strip by rolling a rubber composition continuously discharged from a discharge port of the rubber extrusion means.
The set temperature of the rolling means, the rubber extrusion means inside above the boiling point of the volatile components generated from the rubber composition state, and are 0.99 ° C. or less,
The rubber composition is a silica-based rubber composition containing a silane coupling agent.
A method for producing a rubber strip, which comprises forming a large number of fine foam marks on the entire surface of the rubber strip.

The invention according to claim 2
The method for producing a rubber strip according to claim 1, wherein the set temperature of the rubber extrusion means is higher than the temperature at which the melt fracture of the rubber composition starts and is equal to or lower than the temperature of the rolling means.

The invention according to claim 3
The method for manufacturing a rubber strip according to claim 2, wherein the set temperature of the rubber extrusion means is 30 to 70 ° C.

The invention according to claim 4
The method for manufacturing a rubber strip according to any one of claims 1 to 3, wherein the set temperature of the rolling means is 80 to 120 ° C.

According to the present invention, it is possible to set an appropriate rolling temperature for each of a wide variety of rubber compositions without spending a lot of time and labor, and it is possible to stably produce a rubber strip having a predetermined shape. A technique for manufacturing a rubber strip can be provided.

It is a micrograph of the surface of the rubber strip in one embodiment of the present invention. It is a micrograph of the cross section of the rubber strip in one embodiment of the present invention. It is a schematic diagram which shows the temperature setting method in the manufacturing method of the rubber strip of one Embodiment of this invention. It is a schematic diagram which shows the state of the cross section of the rubber strip in the method of manufacturing the rubber strip of one Embodiment of this invention. It is a schematic diagram which shows the temperature setting method in the conventional rubber strip manufacturing method. It is a schematic diagram which shows the state of the cross section of the rubber strip in the conventional method of manufacturing a rubber strip. It is a schematic diagram which shows the structure of the rubber strip manufacturing apparatus. It is a block diagram which shows the structure in an example of the temperature control mechanism of a rolling means. It is a schematic diagram which shows an example of the control mechanism of a rubber extrusion temperature. It is a micrograph of the surface of the rubber strip of the comparative example. It is a micrograph of the surface of the rubber strip of one Example of this invention. It is a micrograph of the surface of the rubber strip of another embodiment of the present invention.

[1] Problems in the prior art and circumstances leading to the completion of the present invention Before explaining the present invention based on an embodiment, in order to facilitate understanding of the present invention, problems in the prior art and background to the completion of the present invention. , The process leading to the completion of the present invention will be described.

1. 1. Problems in Conventional Technology First, problems in conventional rubber strip manufacturing technology will be described.

FIG. 4 is a schematic view showing the configuration of a rubber strip manufacturing apparatus, and is a side view of the rubber strip manufacturing apparatus 1. In FIG. 4, G is a rubber composition (before molding into a rubber strip), Gs is a rubber strip, 3 is a rubber extruder (rubber extruder), and 4 is a rolling means (calendar roll). And 5 is a take-back roll.

A screw type rubber extruder is widely used as the rubber extruder 3. Further, as the rolling means 4, a pair of upper and lower calendar rolls of 4P and 4F are widely used. For the rubber extrusion means 3, the screw shaft 11 installed inside the cylinder 10 is described for easy understanding.

Conventional rubber strips have been manufactured according to the following procedure using such a rubber strip manufacturing apparatus. The manufacturing procedure is basically the same in the present invention.

First, the rubber composition G obtained by kneading a predetermined compounding material under predetermined conditions (temperature, time, etc.) using a kneader is delivered from the rubber inlet 10A of the rubber extrusion means (rubber extruder) 3. It is thrown into the cylinder 10.

The charged rubber composition G advances in the cylinder 10 while being plasticized by the drive of the rotating screw shaft 11, and is continuously discharged in a predetermined shape from the discharge port 2 provided in the extrusion head 12. NS. As a result, the rubber composition G is preformed into a shape corresponding to the cross-sectional shape of the rubber strips Gs.

The discharged rubber composition G is then sent to a rolling means (calender roll) 4 whose surface temperature is set to a predetermined temperature, and is rolled by passing between a pair of upper and lower calendar rolls 4P and 4F. Is formed into rubber strips Gs having a predetermined cross-sectional shape. After that, the molded rubber strip is peeled off from the calendar roll 4, taken up by the take-up roll 5, sent to the forming drum (not shown), wound around the forming drum, and formed as a low cover. Tires are manufactured by vulcanizing the low cover.

At this time, as described above, if the rubber strips Gs are in close contact with the calendar roll 4, it becomes difficult to peel them off from the calendar roll 4, which causes deformation of the rubber strips Gs. Therefore, rolling is performed by various methods. The temperature setting of the means was appropriately controlled to ensure the releasability of the rubber strips Gs. However, the temperature setting was not easy because it was a trial and error process.

2. Background to Completion of the Present Invention Under such circumstances, the present inventor has diligently studied the mechanism by which the rubber strip is released from the calendar roll. As a result, it was found that as the surface temperature of the calendar roll was raised, the releasability rapidly increased from a certain temperature, and sufficient releasability could be ensured. When the surface of the rubber strip with sufficient releasability was observed in detail, micro-size, specifically, sub-millimeter-level fine foam marks that could not be visually confirmed were present on one surface. I found out. FIG. 1A shows an image obtained by photographing the surface of a rubber strip with sufficient releasability with a microscope. From FIG. 1A, it can be confirmed that a large number of foam marks are present on the entire surface of the rubber strip. FIG. 1A is a microscope image of the surface of the rubber strip obtained at a rolling temperature of 120 ° C. in Experiment 1 described later.

From this result, the present inventor causes the surface temperature of the rubber strip to be finely foamed by raising the surface temperature of the calendar roll, and as a result, the contact area between the rubber strip and the surface of the calendar roll is reduced, resulting in a decrease in adhesiveness. , It was presumed that the releasability was improved.

In such foaming, the rubber composition contains a volatile component generated in the ejection process of the rubber composition, and the volatile component is rapidly vaporized by coming into contact with the calendar roll whose surface temperature has risen. I speculated that it occurred in.

As a specific example, in the case of a silica-based rubber composition, the releasability rises sharply at 80 ° C., and this temperature is almost the boiling point of ethanol generated from the silane coupling agent, 78 ° C. Since they match, it is presumed that the foaming on the surface of the rubber strip is due to the vaporization of ethanol.

Based on this speculation, the present inventor set the surface temperature of the calendar roll to a temperature equal to or higher than the boiling point of the volatile component in order to ensure sufficient releasability of the rubber strip from the calendar roll. It was considered that the surface of the rubber composition discharged from the rubber extrusion means should be heated to a temperature equal to or higher than the boiling point of the volatile component by contacting the rubber composition, and as a result of experiments, it was confirmed that this idea was correct, and the present invention was completed. I came to do it.

Then, in the above experiment, when the rubber composition is passed through the rolling means at a normal linear speed similar to that of conventional rolling, foaming occurs only on the surface of the rubber strip, and the quality such as the density of the rubber strip is improved. It turned out to have little effect. FIG. 1B shows an image of a cross section of the rubber strip taken with a microscope. From FIG. 1B, it was confirmed that foaming occurred only in the extremely thin region of the surface and did not extend to the inside. FIG. 1B is a microscope image of a cross section of the rubber strip obtained at a rolling temperature of 120 ° C. in Experiment 1 described later.

It was also found that the progress of vulcanization on the surface of the rubber strip can be suppressed by setting the temperature of the rolling means to 150 ° C. or lower.

[2] Embodiments of the Invention Hereinafter, the present invention will be specifically described based on the embodiments.

1. 1. Outline of the Present Invention In the method for manufacturing a rubber strip according to the present embodiment, a rubber extrusion means and a rolling means for rolling a rubber composition continuously discharged from a discharge port thereof to form a narrow band-shaped rubber strip are used. It is a manufacturing method for manufacturing a rubber strip used in, for example, a strip wind forming method, and is basically the same as a conventional rubber strip manufacturing method as described above. However, the present embodiment is different from the conventional one in that the set temperature of the rolling means is set to 150 ° C. or higher, which is equal to or higher than the boiling point of the volatile component generated from the rubber composition inside the rubber extrusion means.

In the production of rubber strips, a chemical reaction usually occurs between the compounding materials of the rubber composition during the extrusion process by the rubber extrusion means, and volatile components such as ethanol and water derived from, for example, a silane coupling agent are generated. .. Therefore, by setting the set temperature of the rolling means to be equal to or higher than the boiling point of the volatile component, the volatile component in the rubber composition in contact with the rolling means is heated and vaporized, and foams on the surface of the rubber composition. Since the contact area between the surface of the rolling means and the surface of the rubber composition decreases with this foaming, the adhesive force (tack) to the rolling means decreases, and sufficient releasability can be ensured.

As described above, according to the present invention, if the volatile component generated inside the rubber extrusion means is specified, the temperature of the rolling means can be immediately and appropriately set corresponding to the boiling point of the volatile component. Then, the volatile component can be easily specified based on the constituent material of the rubber composition. As a result, the appropriate temperature of the rolling means can be set without spending a lot of time and labor. Further, since rolling is performed at an appropriate temperature having good releasability, a rubber strip having a predetermined shape can be stably manufactured.

2. Rubber Strip Manufacturing Method As described above, the rubber strip manufacturing method of the present embodiment is basically the same as the conventional rubber strip manufacturing method except for the temperature setting of the rolling means. In the description, the temperature setting of the rolling means will be mainly described.

(1) Temperature setting of rolling means In the present embodiment, the temperature of the rolling means is set to 150 ° C. or higher, which is equal to or higher than the boiling point of the volatile component, as described above. As a result, as described above, the volatile components in the rubber composition in contact with the rolling means are heated and vaporized, and foamed on the surface of the rubber composition. Since the contact area between the rolling means and the surface of the rubber composition decreases with foaming, sufficient releasability can be ensured, while vulcanization in the rubber strip is performed by setting the temperature to 150 ° C. or lower. It is possible to suppress the progress of the rubber strip and produce a rubber strip of stable quality.

The "temperature" of the "setting temperature of the rolling means" referred to here is the temperature of the surface of the rolling means that comes into direct contact with the rubber composition when the rubber composition is rolled, and is a control connected to the rolling means. Controlled by means.

In the present embodiment, the volatile component generated in the rubber composition during the extrusion step by the rubber extrusion means is not particularly limited, and for example, when the compounding material contains an ethoxysilane-based silane coupling agent. , Ethanol (boiling point: 78 ° C) or water is generated as a volatile component, and when the compounding material contains a methoxysilane-based silane coupling agent, methanol (boiling point: 65 ° C) is used as the volatile component. appear. The water may be generated as normal pressure water (boiling point: 95 ° C.) or as pressurized water (boiling point: 120 ° C.). Then, these volatile components can be easily specified depending on the compounding material in the rubber composition.

Since these volatile components may volatilize even during the extrusion process, it is possible to suppress the volatilization of the volatile components during the extrusion process by using a closed rubber extruder as the extrusion means of the present embodiment. preferable. In the compounding of the rubber composition, a volatile material may be blended, but since such a volatile material volatilizes in a kneading step in a kneader that is performed at a high temperature for a long time, the inside of the extrusion means The volatile components generated in the above-mentioned effect of the present invention are exhibited.

The method for producing a rubber strip of the present embodiment is particularly suitable for producing a rubber strip made of a rubber composition using a rubber composition containing a silane coupling agent. Silane coupling agents are widely used to enhance the dispersibility of inorganic reinforcing materials (fillers) such as carbon black and silica. In particular, when silica is used, which has a hydrophilic silanol group on the surface, has a low affinity for a rubber component (polymer) or oil, and has poor dispersibility in a rubber composition, a silane coupling agent is usually added. It enhances dispersibility and suppresses deterioration of rubber wear resistance and mechanical strength.

As the silane coupling agent, alkoxysilane compounds such as bis (3-triethoxysilylpropyl) tetrasulfide and bis (3-triethoxysilylpropyl) disulfide are usually used. When these silane coupling agents are used, the coupling reaction by hydrolysis of the silane coupling agent proceeds in the rubber extrusion process, the rubber component and the inorganic filler are chemically bonded, and volatile components such as ethanol are released. appear. In addition, the silane coupling agent contains water that is a material for hydrolysis. Therefore, it is not necessary to separately add a volatile component as a compounding material for the rubber composition. Further, the conventional kneading technique and rubber extrusion technique can be applied as they are.

When such ethanol is generated, the set temperature of the rolling means is preferably set in the range of 80 to 120 ° C. Since 80 ° C. is a temperature higher than the boiling point of the volatile component ethanol, by setting the temperature of the rolling means to 80 ° C. or higher, the temperature of the surface of the rubber strip during rolling is surely set to a temperature higher than the boiling point of ethanol. Can be heated. On the other hand, by setting the upper limit of the set temperature of the rolling means to 120 ° C., which is lower than 150 ° C., which is the temperature at which vulcanization of the rubber composition proceeds, the progress of vulcanization can be reliably prevented. .. When the temperature is set to 120 ° C., pressurized water can be volatilized in addition to ethanol.

(2) Temperature setting of rubber extrusion means In the above, the temperature setting of the rolling means has been described, but when the temperature setting of the rubber extrusion means is set to the same high temperature as the rolling means, the rubber composition is overplasticized. The strength of the waist is insufficient, and no matter how much the releasability in the rolling means is improved, there is a risk that the rubber strip will be cut off when it is peeled off from the calendar roll or when it is picked up. Here, the waist strength of the rubber strip is a value using the maximum value of the tensile stress of the unvulcanized rubber strip (green rubber strip) as an index.

However, if the temperature setting of the rubber extrusion means is lowered, a melt fracture phenomenon occurs in the rubber extrusion process and the rubber is rolled as it is, which may result in a defective rubber strip. It should be noted that this melt fracture phenomenon is a phenomenon in which the entire extruded product is pulsating and the flow is greatly disturbed, and the shape such as thickness and width is also extruded into a distorted shape. It is known that the lower the temperature of the rubber composition, the more likely it is to occur. ing.

Therefore, in addition to setting the temperature of the rolling means, it is preferable to appropriately set the temperature of the rubber extrusion means. Specifically, the temperature is higher than the temperature at which the melt fracture of the rubber composition starts and is equal to or lower than the temperature of the rolling means. It is preferably temperature. Since the temperature at which the melt fracture starts differs depending on the composition of the rubber composition, the physical properties such as viscoelasticity, the discharge rate, and the like, the lower limit of the rubber extrusion temperature is appropriately set according to these conditions.

In this way, the temperature of the rubber extrusion means and the temperature of the rolling means are set individually, and the temperature of the rubber extrusion means is set to a temperature higher than the temperature at which the melt fracture of the rubber composition starts and equal to or lower than the temperature of the rolling means. By doing so, while preventing the generation of defective products due to melt fracture in the rubber extrusion process, the strength of the rubber composition is secured, and the temperature of the rolling means is set to 150 ° C. or higher, which is higher than the boiling point of the volatile component. As a result, excellent mold releasability can be ensured, and a rubber strip of stable quality can be produced.

Then, according to an experiment, the present inventor can foam the surface at the time of rolling even if the temperature of the rubber extrusion means is set low, and the strength of the waist of the rubber strip immediately after rolling is the rubber composition before rolling. It has inherited the strength of the object and confirmed that it was hardly reduced by rolling. From this, the temperature of the rubber extrusion means is set to a temperature at which the rubber strip can be stably peeled off from the rolling means without being deformed due to stretching, etc., in addition to the set temperature of the rolling means. It turned out that it is preferable to set it.

That is, in the case of the conventional rubber strip manufacturing method, it is common to control the temperature of the rolling means and the temperature of the rubber extrusion means to the same temperature. FIG. 3A is a schematic view showing a temperature setting method in a conventional rubber strip manufacturing method. In FIG. 3A, the vertical axis is the waist strength of the tack and the rubber strip, and the horizontal axis is the temperature. Further, FIG. 3B is a schematic view showing a cross section of the rubber strips Gs after rolling.

As shown in FIG. 3A, conventionally, with respect to the temperature of the rubber extrusion means and the temperature of the rolling means, T ₃ is changed up and down to obtain a temperature suitable for peeling by trial and error. However, in such a method, since the waist of the rubber strip is lower than the tack in a wide temperature range, it takes a lot of time and effort to secure the waist of the rubber strip and at the same time to obtain a suitable temperature for peeling. there were. Then, as shown in FIG. 3B, the obtained rubber strip is uniform from the inside to the surface portion.

On the other hand, in the present embodiment, as described above, the temperature of the rolling means and the temperature of the rubber extrusion means are set separately. FIG. 2A is a schematic view showing a method of setting a temperature in the method of manufacturing a rubber strip of the present embodiment, and shows a relationship between the strength of the waist of the tack and the rubber strip (rubber) and the temperature. Note that FIG. 2A and FIG. 3A have the same data. FIG. 2B is a schematic view showing the state of the cross section of the rubber strip Gs after rolling, and shows that the state of the inside I and the surface portion S of the rubber strip Gs are different.

As shown in FIG. 2A, in the present embodiment, the temperature of the rubber extrusion means _{is set to T 1} , while the temperature of the rolling means is set to _{T 2.} Therefore, in the rubber extrusion step, it is possible to secure sufficient waist strength, while in the rolling process, it is possible to secure sufficient releasability with a tack lower than the waist strength and roll. Then, as shown in FIG. 2B, the obtained rubber strip is uniformly chewy rubber at the inside I, while foam marks are formed on the surface portion S.

Further, in the present embodiment, since the temperature of the rubber extrusion means is set higher than the temperature at which the melt fracture starts, the melt fracture does not occur. Therefore, it is possible to prevent the generation of defective rubber strips due to melt fracture.

The "temperature" of the "set temperature of the rubber extrusion means" referred to here is the temperature of the discharge port set for extruding the rubber composition at a predetermined temperature from the discharge port of the rubber extrusion means, and is rubber. The temperature is set to a predetermined temperature by the control means connected to the extrusion means.

Specifically, in the present embodiment, the set temperature of the rubber extrusion means is preferably set in the range of 30 to 70 ° C, more preferably 30 to 50 ° C.

By setting the upper limit of the set temperature of the rubber extrusion means to 70 ° C., more preferably 50 ° C., the rubber composition having a sufficiently high level of waist strength can be extruded.

Further, the melt fracture start temperature when extruding a rubber composition used for a tire rubber material such as a tread under normal conditions is generally about 20 ° C., and in the present embodiment, the temperature of the rubber extrusion means. Since the lower limit of is set to 30 ° C., which is higher than that, extrusion can be reliably performed under normal extrusion conditions without generating melt fracture.

By setting the temperature of the rubber extrusion means to a temperature significantly lower than the boiling point of the volatile component in this way, not only the firmness of the rubber is secured, but also the volatilization of the volatile component before the rolling process is sufficiently suppressed. Can be preferred.

(3) Rubber Composition The method for producing a rubber strip of the present embodiment can be used for a wide variety of rubber compositions, and among them, for example, studless tires, winter tires, and all-season tires. It is preferably used for rubber compositions containing high oils used in the manufacture of tires and the like and which are easily affected by temperature. The rubber composition containing a high amount of oil refers to a rubber composition in which 20 parts by mass or more of oil is mixed with 100 parts by mass of the rubber component, and the oil includes, for example, process oil, vegetable oil, and a mixture thereof. And so on.

The rubber composition usually contains, together with oil, a rubber component as a main component, and various compounding materials such as reinforcing materials such as carbon black and silica, and additives.

3. 3. Rubber Strip Manufacturing Equipment The rubber strip manufacturing equipment described below is used for manufacturing the rubber strips described above. That is, the rubber strip manufacturing apparatus according to the present embodiment includes a rubber extruder and a pair of upper and lower calendar rolls, and the surface temperature of the calendar rolls is equal to or higher than the boiling point of the volatile component generated from the rubber composition. It is characterized in that a roll temperature control means for controlling the temperature to 150 ° C. or lower is provided.

Further, in the present embodiment, a discharge temperature control means for controlling the discharge temperature of the rubber composition to a temperature higher than the temperature at which the melt fracture of the rubber composition starts and equal to or lower than the surface temperature of the calendar roll is provided. Is preferable.

Hereinafter, the roll temperature control means and the discharge temperature control means, which are characteristic portions of the present embodiment, will be described.

(1) Roll temperature control means The roll temperature control means controls the surface temperature of the calendar roll to 150 ° C. or higher than the boiling point of the volatile component generated from the rubber composition inside the rubber extrusion means. For example, FIG. A known temperature control mechanism as shown in 1 can be used.

FIG. 5 is a block diagram showing a configuration of a temperature control mechanism of the rolling means. As shown in FIG. 5, in this temperature control mechanism, a heating step of heating the rolling means (calendar roll) 4, a detection step of measuring the temperature of the outer peripheral surface of the rolling means 4, and a type of rubber composition G. A set temperature Ts preset according to at least one piece of information among the temperature, shape and rolling speed is compared with the detection temperature Tk detected in the detection step, and when the detection temperature Tk is low, the rolling means The rolling means 4 is configured to be feedback controlled, including a temperature control step of heating 4 and holding the temperature of the rolling means 4 at a set temperature Ts.

(2) Discharge Temperature Control Means The discharge temperature control means controls the discharge temperature of the rubber composition to a temperature higher than the temperature at which the melt fracture of the rubber composition starts and lower than the surface temperature of the calendar roll, for example. , A known temperature control mechanism as shown in FIG. 6 as an example can be used.

FIG. 6 is a schematic view showing a control mechanism of the rubber extrusion temperature. As shown in FIG. 6, in this temperature control mechanism, the motor 13 is controlled by the control means 16 from the measurement result of the rubber extrusion temperature of the temperature sensor 14, and the rotation speed of the screw shaft 11 of the rubber extruder 3 is controlled. As a result, the rubber extrusion temperature is configured to be feedback controlled.

Next, the present invention will be described in more detail with reference to Examples.

[1] Experiment 1
In Experiment 1, the releasability of the rubber strip and the presence or absence of foaming on the surface of the rubber strip were investigated by changing the set temperature of the rolling means. In Experiment 1, since the silane coupling agent was blended, the volatile components generated inside the extrusion means were ethanol (boiling point 78 ° C.) or methanol (boiling point 65 ° C.) and water (normal pressure water).

1. 1. Production of Rubber Composition First, using the following compounding materials, rubber compositions for treads of two types of studless tires, A and B, were kneaded according to the composition shown in Table 1. The blending amount is parts by mass.

Natural rubber (NR): RSS # 3
Butadiene rubber (BR): BR1220 manufactured by Nippon Zeon Corporation
Carbon Black: Seest N220 manufactured by Mitsubishi Chemical Corporation
Silica: Ultrasil VN3 manufactured by Evonik Degussa
Silane coupling agent (1): Si75 manufactured by Evonik Degussa
(Bis (3-triethoxysilylpropyl) disulfide)
Silane coupling agent (2): LS-535 manufactured by Shin-Etsu Chemical Co., Ltd.
(Mercaptomethyltrimethoxysilane)
Oil: Process X-140 (aroma oil) manufactured by Japan Energy Co., Ltd.
Wax: Sunknock N manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Zinc oxide: Zinc oxide No. 1 made by Mitsui Metal Mining Co., Ltd. Stearic acid: Stearic acid "Tsubaki" made by NOF CORPORATION
Anti-aging agent: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd.
Sulfur: Powdered sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd. (1): Noxeller CZ manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator (2): Noxeller D manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

2. Production and Evaluation of Rubber Strip Next, the obtained rubber composition G was extruded by setting the temperature of the rubber extrusion means to 30 ° C. and the extrusion speed to 6.0 m / min.

Next, the extruded rubber composition was subjected to rolling speed (linear speed 6.6 m / min) and the set temperature of the rolling means was set to 50 ° C., 70 ° C., 80 ° C., 105 ° C., 120 ° C., 150 ° C., 160. Rolling was carried out at a temperature of 1.5 mm to produce rubber strips having a thickness of 1.5 mm and a width of 20 mm (100 m each).

At this time, the releasability of the rubber strip to the calendar roll was evaluated. Specifically, the tack of each rubber strip was measured by the following tack test method. In addition, the surface of the obtained rubber strip was observed with a microscope to evaluate the presence or absence of foaming marks on the surface.

(Tack test)
The tack (N) was measured using a "PICMA tack tester" manufactured by Toyo Seiki Seisakusho as an adhesiveness tester. Specifically, each rubber strip is prepared, and this test piece is subjected to an aluminum adhesive portion under the conditions of a temperature of 23 ° C., a crimping load of 4.9 (N), and a crimping time of 10 seconds in accordance with JIS T9233. It was crimped to the disk. Then, under the condition of a speed of 10 (mm / min), the adhesive portion was peeled off, and the maximum value of the force at the time of peeling off was obtained and used as the tack value (average value of 5 measurements).

3. 3. Evaluation Results Table 2 shows the releasability and tack test results of the rubber strips manufactured by rolling at each temperature for the calendar roll.

As shown in Table 2, in both the formulations A and B, overadhesion occurred when the set temperature of the rolling means 4 was 50 ° C. On the other hand, at 80 ° C., 105 ° C., 120 ° C., 150 ° C., and 160 ° C., overadhesion did not occur, and the rubber strip could be peeled off from the rolling means without stretching. The tack is as high as 12.0 N in formulation A and 11.4 N in formulation B at 50 ° C., but in formulation A it is 80 ° C or higher, which is higher than the boiling point of ethanol, which is a volatile component, and in formulation B, it is higher than the boiling point of methanol, which is a volatile component. In all of the rolled products at 70 ° C. or higher, the values were lower than the measured values at 50 ° C., and it was confirmed that this reduction in tack caused good mold releasability. On the other hand, in the case of rolling at 160 ° C., although the releasability was good, the tack value decreased sharply and the progress of vulcanization was confirmed on the surface. It was found that rolling above ° C was not suitable.

FIG. 7 shows the observation result of the rolling means 4 at the set temperature of 50 ° C., FIG. 8 shows the observation result of the set temperature of 80 ° C., FIG. 9 shows the observation result of the set temperature of 105 ° C., and FIG. 1A shows the observation result of the set temperature of 120 ° C. Shown in. From these figures, no trace of foaming was observed at 50 ° C., which is lower than the boiling point of ethanol, whereas traces of foaming were observed at 80 ° C., 105 ° C., and 120 ° C. above the boiling point. It turned out that.

From the above results, when the temperature of the rolling means is set to be equal to or higher than the boiling point of ethanol or methanol, which is a volatile component generated in the rubber composition, foaming occurs on the surface of the rubber composition and the releasability is improved. It could be confirmed.

[2] Experiment 2
In Experiment 2, a rubber composition was produced by changing the set temperature of the rubber extrusion means, and each rubber composition was rolled at the same temperature to produce a rubber strip. Was tested.

1. 1. Manufacturing of rubber strips The rubber composition for treads of studless tires is blended in the same formulation as formulation A in Experiment 1, and the set temperatures of the rubber extrusion means are set to 5 levels of 20 ° C, 30 ° C, 50 ° C, 70 ° C, and 90 ° C. The rubber composition was extruded under extrusion conditions at an extrusion rate of 6.0 m / min. The obtained rubber composition was rolled at a set temperature of a rolling means at 80 ° C. and a rolling speed (linear speed of 6.6 m / min) to produce a rubber strip having a thickness of 1.5 mm and a width of 20 mm.

2. Evaluation The waist (green TB) of the manufactured rubber strip was measured and evaluated by a tensile property test.

Specifically, the tensile properties (tensile strength) of the produced rubber strip (unvulcanized) were measured in accordance with the provisions of ASTM6746-10 (measurement temperature: 21 ° C.). That is, a test piece was prepared in a shape having a length of 10 cm, a width of 10 mm, and a thickness of 2.5 mm, heated at the set temperature at the time of rubber ejection for 5 minutes, and then subjected to a tensile test at 21 ° C. (tensile rate: 100 mm /). min).

3. 3. Evaluation Results The evaluation results are shown in Table 3. The test result is the average of three measurements, and the maximum value of tensile stress is shown as the waist of the rubber.

As shown in Table 3, the rubber waist showed a suitable rubber waist of 0.3 to 0.8 when the set temperature of the rubber extrusion means was 30 to 70 ° C. At 90 ° C., the waist of the rubber was very low at 0.1. From this result, it was found that the set temperature of the rubber extrusion means is preferably 30 to 70 ° C, more preferably 30 to 50 ° C, and particularly preferably 40 ° C. At 20 ° C., melt fracture was generated on the rubber surface, so that the strip was suddenly broken from the constricted portion, and the rubber waist was estimated to be extremely small.

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

1 Rubber strip manufacturing equipment 2 Discharge port 3 Rubber extrusion means (rubber extruder)
4, 4F, 4P rolling means (calendar roll)
5 Take-up roll 10 Cylinder 10A Rubber inlet 11 Screw shaft 12 Extrusion head 13 Motor 14 Temperature sensor 16 Control means G Rubber composition Gs Rubber strip I Inside rubber strip S Surface part of rubber strip

Claims (4)

A method for manufacturing a rubber strip using a rolling means for forming a narrow band-shaped rubber strip by rolling a rubber composition continuously discharged from a discharge port of the rubber extrusion means.
The set temperature of the rolling means, the rubber extrusion means inside above the boiling point of the volatile components generated from the rubber composition state, and are 0.99 ° C. or less,
The rubber composition is a silica-based rubber composition containing a silane coupling agent.
A method for producing a rubber strip, which comprises forming a large number of fine foam marks on the entire surface of the rubber strip. The method for producing a rubber strip according to claim 1, wherein the set temperature of the rubber extrusion means is higher than the temperature at which the melt fracture of the rubber composition starts and is equal to or lower than the temperature of the rolling means. The method for producing a rubber strip according to claim 2, wherein the set temperature of the rubber extrusion means is 30 to 70 ° C. The method for producing a rubber strip according to any one of claims 1 to 3, wherein the set temperature of the rolling means is 80 to 120 ° C.

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