JP2021036009A - Production method of synthetic rubber - Google Patents

Abstract

To provide a production method of a synthetic rubber, capable of effectively suppressing the deformation of the sheet-like synthetic rubber in extrusion molding so as to secure the shape stability of the extruded product.SOLUTION: Hydrous crumbs are formed by supplying and stirring a polymer latex, a coagulant and water in a coagulation tank at a preset temperature. After cleaning in a cleaning tank 40, the hydrous crumbs are supplied to an extrusion and drying machine 5, and subject to compression dewatering by the extrusion and drying machine 5. The moisture is then evaporated, and a sheet-like synthetic rubber having a water content equal to or less than a specified level is extruded. Both sides of the sheet-like synthetic rubber 15 immediately after extruded from a discharge port of the extrusion and drying machine 5 are brought into contact with a roller 12 as a component for forming a side extending in approximately vertical direction relative to the sheet surface of the sheet-like synthetic rubber 15.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for producing synthetic rubber, and particularly to a method for producing synthetic rubber suitable for producing acrylic rubber sheets and veils.

Synthetic rubber, for example, acrylic rubber is a polymer containing acrylic acid ester as a main component, and is generally known as rubber having excellent heat resistance, oil resistance, and ozone resistance, and is widely used in automobile-related fields and the like. ..

In such a synthetic rubber, usually, the monomer component constituting the rubber is emulsion-polymerized, the obtained emulsion polymerization solution is brought into contact with a coagulant, the obtained hydrous crumb is dried to a predetermined moisture content or less, and then the veil is used. It is shipped as a product in a modified state.

As a conventional method for producing this type of synthetic rubber, for example, in Patent Document 1, at least one kneading disk is provided in a compression / dehydration section containing a screw, and an expansion type extrusion having a heating device in a die plate. It is disclosed that a drier is used to compress and dehydrate a hydrous crumb, and then the residual water is rapidly vaporized by releasing pressure at the time of extrusion.

Further, in Patent Document 2, a shape in which a plurality of guide plates parallel to the two screw shafts intersect each other on the central axes of both screw shafts on the inner side of the die portion of the extruder in which the hydrous crumb is extruded. The breaker plate is arranged so as to suppress the thickness of the sheet-shaped rubber sheet extruded from the slit of the die portion after kneading with the biaxial screw shaft.

Japanese Unexamined Patent Publication No. 6-278132 Japanese Unexamined Patent Publication No. 1-225512

However, in the conventional method for producing synthetic rubber as described above, depending on the type of synthetic rubber, residual moisture is released from a high temperature / high pressure state to atmospheric pressure at the time of extrusion after kneading with a twin-screw screw. Due to the rapid evaporation and vaporization of the rubber, and the excess and deficiency of the rectifying action by the breaker plate, the sheet-shaped synthetic rubber immediately after being extruded from the die part undergoes deformation other than the thickness variation. As a result, there is a problem that the shape stability of the product after extrusion may be impaired.

Therefore, an object of the present invention is to realize a method for producing a synthetic rubber capable of effectively suppressing deformation of a sheet-shaped synthetic rubber to be extruded during extrusion and ensuring the shape stability of a product after extrusion. Is what you do.

In order to achieve the above object, the method for producing a synthetic rubber of the present invention comprises a coagulation step of supplying a polymer latex, a coagulant and water into a coagulation tank at a set temperature and stirring them to generate a water-containing crumb, and the water-containing crumb. And the washing water are supplied to the washing tank and stirred to wash the water-containing crumbs, and the water-containing crumbs after washing are supplied to the material supply zone of the extruder and dried by compression and dehydration by the extruder. A method for producing synthetic rubber, which comprises an extrusion-drying step of evaporating water by heating and kneading to extrude a synthetic rubber having a predetermined water content or less into a sheet shape, which is extruded from a discharge port of the extrusion dryer. Immediately after, both side surfaces of the sheet-shaped synthetic rubber are brought into contact with a side forming member extending in a direction substantially perpendicular to the sheet surface of the sheet-shaped synthetic rubber.

With this configuration, in the present invention, the sheet-shaped synthetic rubber immediately after being extruded by the extruder is swelled, collapsed, or deformed in the thickness direction near both side surfaces, which is substantially perpendicular to the sheet surface. It is effectively suppressed by coming into contact with the side forming member extending to the surface, and the unstable sheet shape is effectively suppressed. Therefore, it is possible to suppress variations in the product shape of the cut sheet-shaped synthetic rubber obtained in the subsequent process.

In the method for producing synthetic rubber of the present invention, a pair of side forming members in contact with each of both side surfaces of the sheet-shaped synthetic rubber are provided on the downstream side of the discharge port at intervals in the sheet width direction. You may be.

In this case, each of the pair of side forming members can form each of the side surfaces of the sheet-shaped synthetic rubber.

In the method for producing synthetic rubber of the present invention, the side forming member is a roller that can rotate about an axis in a substantially vertical direction, and the side surface of the sheet-shaped synthetic member extruded from the discharge port is the same. You may make contact.

By doing so, it is possible to prevent a load that resists the extrusion of the sheet-shaped synthetic member from being generated, and to form the side surface of the sheet-shaped synthetic rubber while maintaining a smooth pushing operation.

According to the present invention, it is possible to realize a method for producing a synthetic rubber capable of effectively suppressing deformation of a sheet-shaped synthetic rubber to be extruded during extrusion and ensuring the shape stability of a product after extrusion.

It is a schematic block diagram of the synthetic rubber manufacturing system which concerns on one Embodiment of this invention. It is a schematic block diagram of the main part of the screw type extrusion dryer in the synthetic rubber manufacturing system which concerns on one Embodiment of this invention. (A) is a perspective view of the vicinity of a die portion for extruding a sheet-shaped synthetic rubber from the screw type extruder / dryer of FIG. 2, and (b) is a vertical cross-sectional view of the die portion. It is a flowchart which shows the outline procedure of the synthetic rubber manufacturing method which concerns on one Embodiment of this invention.

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

First, a synthetic rubber manufacturing system according to an embodiment of the present invention that can be used for manufacturing synthetic rubber will be described.

The synthetic rubber manufacturing system according to the present embodiment can be used for manufacturing acrylic rubber, for example, and although acrylic rubber will be described below as an example, it is also used for manufacturing synthetic rubber other than acrylic rubber. Can be done.

Examples of other synthetic rubbers include styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), styrene-isoprene block polymer (SIS), styrene-butadiene block polymer (SBS), and nitrile butadiene rubber. Diene rubber such as (NBR) and chloroprene rubber (CR), butyl rubber (IIR), ethylene-propylene-dienter polymer rubber (EPDM), acrylic rubber, chlorosulfonated polyethylene rubber, olefin rubber such as fluororubber, silicone. Examples include rubber and urethane rubber.

As shown in FIG. 1, the synthetic rubber manufacturing system 1 according to the present embodiment includes an emulsion polymerization apparatus (not shown), a coagulation apparatus 3, a cleaning apparatus 4, a screw type extruder / dryer 5, a transport type cooling apparatus 6, and a cutting apparatus 7. , And a bale device 8. The screw type extruder 5 of the present embodiment corresponds to the extruder of the present invention. Further, as will be described in detail later, the method for producing synthetic rubber according to the embodiment of the present invention includes an emulsion polymerization step, a solidification step, a washing step, an extrusion drying step, a transport cooling step, a cutting step, and a bale step. Includes. Hereinafter, each of the above-mentioned devices used in these steps will be described.

[Emulsion polymerization equipment]
The emulsion polymerization apparatus (not shown) is an apparatus used for the treatment related to the emulsion polymerization step in the method for producing synthetic rubber according to the present embodiment. Specifically, the emulsion polymerization apparatus mixes water and an emulsifier with a monomer component for forming acrylic rubber in a reactor and emulsifies it while appropriately stirring with a stirrer, and in the presence of a polymerization catalyst. An emulsion polymerization solution is obtained by emulsion polymerization. The reactor of the emulsion polymerization apparatus according to the present embodiment is a continuous type in which the raw material is charged into the reactor, the reaction is carried out, and the product is recovered at the same time. Good. The reactor of the emulsion polymerization apparatus according to the present embodiment is a tank type reactor, but may be a tube type reactor.

[Coagulator]
The coagulation device 3 is an device used for a process related to a coagulation step in the synthetic rubber manufacturing method according to the present embodiment. Specifically, the coagulation apparatus 3 is adapted to generate a hydrous crumb by bringing the emulsion polymerization solution obtained by the emulsion polymerization apparatus into contact with the coagulation solution as a coagulant and coagulating it. As shown in FIG. 2, the coagulation apparatus 3 according to the present embodiment heats the inside of the coagulation tank 30 and the coagulation tank 30 that house the emulsion polymerization solution and the coagulation solution obtained by the emulsion polymerization apparatus, and maintains a desired temperature. The heating device 31 and the stirring device 34 for stirring the emulsion polymerization liquid and the coagulating liquid contained in the coagulation tank 30 are provided.

The coagulation tank 30 is composed of, for example, a closed bottom portion and a cylindrical side wall portion so that the emulsion polymerization liquid and the coagulation liquid can be stored. The heating device 31 includes a heating unit 32 that heats the inside of the coagulation tank 30, and a temperature control unit (not shown) that controls the temperature inside the coagulation tank 30. The stirring device 34 is not shown to control the rotation speed and rotation speed of the stirring blade 35, which is a member that is arranged in the coagulation tank 30 and rotates around a predetermined axis, the motor 36 that rotates the stirring blade 35, and the stirring blade 35. It has a drive control unit.

In the coagulation apparatus 3 of the present embodiment, a method of adding the emulsion polymerization solution to the stirring coagulation solution is adopted for the contact between the emulsion polymerization solution and the coagulation solution. That is, a hydrous crumb is generated by filling the coagulation tank 30 of the coagulation device 3 with a coagulation liquid and adding and contacting the emulsion polymerization liquid with the coagulation liquid to coagulate the emulsion polymerization liquid.

The heating device 31 of the coagulation device 3 is configured to heat the coagulation liquid filled in the coagulation tank 30. Specifically, the heating device 31 sends steam to a jacket as a heating unit 32 provided on the outer periphery of the coagulation tank 30, and exchanges heat between the steam and the coagulation tank 30 or the coagulation liquid in the coagulation tank 30. The coagulant is heated.

The temperature control unit (not shown) of the coagulation device 3 controls the temperature inside the coagulation tank 30 by controlling the heating operation by the heating unit 32 while monitoring the temperature inside the coagulation tank 30 measured by a thermometer. It is configured as follows. The temperature of the coagulating liquid in the coagulation tank 30 is controlled by a temperature control unit so as to be usually in the range of 40 ° C. or higher, preferably 40 to 90 ° C., and more preferably 50 to 80 ° C.

In order to control the temperature of the liquid phase in the coagulation tank 30 to a set temperature, for example, one control system for controlling the temperature and flow rate of steam for heating the coagulation tank 30, hot water supplied in the coagulation tank 30, and the like. A cascade control type liquid phase temperature control system may be configured in which the other control system for controlling the temperature is used in combination.

The stirring device 34 of the coagulation device 3 is configured to stir the coagulating liquid filled in the coagulation tank 30. Specifically, the stirring device 34 includes a motor 36 that generates rotational power and a stirring blade 35 that spreads in a direction perpendicular to the rotation axis of the motor 36. The stirring blade 35 causes the coagulation liquid to flow by rotating around the rotation axis by the rotational power of the motor 36 in the coagulation liquid filled in the coagulation tank 30. The shape and size of the stirring blades 35, the number of installations, and the like are appropriately determined in consideration of the required stirring strength and the like.

The drive control unit (not shown) of the solidifying device 3 is configured to control the rotational drive of the motor 36 of the stirring device 34 to set the rotation speed and the rotation speed of the stirring blade 35 of the stirring device 34 to predetermined values. ing. The rotation of the stirring blade 35 is controlled by the drive control unit so that the stirring number of the coagulating liquid is, for example, usually 100 rpm or more, preferably 200 to 1000 rpm, more preferably 300 to 900 rpm, and particularly preferably 400 to 800 rpm. Will be done. The peripheral speed of the coagulant is usually 0.5 m / s or more, preferably 1 m / s or more, more preferably 1.5 m / s or more, particularly preferably 2 m / s or more, and most preferably 2.5 m / s or more. The rotation of the stirring blade 35 is controlled by the drive control unit. Further, the drive control unit agitates the coagulant so that the upper limit of the peripheral speed is usually 50 m / s or less, preferably 30 m / s or less, more preferably 25 m / s or less, and most preferably 20 m / s or less. The rotation of the wing 35 is controlled.

The coagulation device 3 overflows the generated hydrous crumb from the coagulation tank 30 together with warm water, takes it out of the coagulation tank 30, and supplies it to the cleaning device 4 that performs the cleaning step. A drainer 39 capable of separating free water from the water-containing crumb is arranged between the coagulator 3 and the cleaning device 4, and the water-containing crumb is supplied to the cleaning device 4 through the drainer 39. It has become like. The water separated by the drainer 39 is collected in a tank (not shown). The water stored in the tank is sent to the coagulation tank 30 by a pump for reuse.

[Washing device]
The cleaning device 4 is a device used for a process related to a cleaning step in the synthetic rubber manufacturing method according to the present embodiment. Specifically, the cleaning device 4 cleans the water-containing crumb generated by the coagulation device 3 with cleaning water. As shown in FIG. 1, the cleaning device 4 according to the present embodiment heats the inside of the cleaning tank 40 and the cleaning tank 40 that contain the water-containing crumb and the cleaning water generated by the solidifying device 3 and maintains a desired temperature. It is provided with a heating device 41 and a stirring device 44 for stirring the hydrous crumb and the washing water contained in the washing tank 40.

The cleaning tank 40 is composed of, for example, a closed bottom portion and a cylindrical side wall portion so that a water-containing crumb and cleaning water can be stored. The heating device 41 includes a heating unit 42 that heats the inside of the cleaning tank 40, and a temperature control unit (not shown) that controls the temperature inside the cleaning tank 40. The stirring device 44 is not shown to control the rotation speed and rotation speed of the stirring blade 45, which is a member that is arranged in the cleaning tank 40 and rotates around a predetermined axis, the motor 46 that rotates the stirring blade 45, and the stirring blade 45. It has a drive control unit. In the cleaning device 4, the amount of ash in the finally obtained acrylic rubber sheet or acrylic rubber veil is effectively reduced by mixing the hydrous crumb generated by the coagulator 3 with a large amount of water and cleaning. Can be done.

The heating device 41 of the cleaning device 4 is configured to heat the inside of the cleaning tank 40. Further, the temperature control unit of the cleaning device 4 controls the temperature inside the cleaning tank 40 by controlling the heating operation by the heating unit 42 while monitoring the temperature inside the cleaning tank 40 measured by the thermometer. It is configured. As described above, the temperature of the washing water in the washing tank 40 is usually controlled to be in the range of 40 ° C. or higher, preferably 40 to 100 ° C., more preferably 50 to 90 ° C., and most preferably 60 to 80 ° C. To.

The cleaning device 4 overflows the water-containing crumb after cleaning from the cleaning tank 40 together with the cleaning water, takes it out of the cleaning tank 40, and supplies it to the screw type extrusion dryer 5 that performs the dehydration step and the drying step. .. A drainer 49 capable of separating free water from the water-containing crumb after cleaning is arranged between the cleaning device 4 and the screw type extruder 5 and the water-containing crumb is screwed through the drainer 49. It is designed to be supplied to the mold extruder 5. A screen is used for the drainer 49 of the present embodiment, but for example, a wire mesh, an electric sieve, or the like can also be used. The free water separated by the drainer 49 is collected in a tank (not shown). The water stored in the tank is sent to the coagulation tank 30 by a pump for reuse.

Further, when the water-containing crumb after cleaning is supplied to the screw type extruder 5, the temperature of the water-containing crumb is preferably 40 ° C. or higher, more preferably 60 ° C. or higher. For example, by setting the temperature of the water used for washing in the washing device 4 to 40 ° C. or higher, preferably 60 ° C. or higher (for example, 70 ° C.), the temperature of the water-containing crumb when supplied to the screw type extruder 5 is set. The temperature of the hydrous crumb may be maintained at 40 ° C. or higher, preferably 60 ° C. or higher, and the temperature of the water-containing crumb is 40 ° C. or higher, preferably 60 ° C. or higher when transferred from the cleaning device 4 to the screw type extruder dryer 5. You may heat it so that it becomes. This makes it possible to effectively perform dehydration in the dehydration step, which is a subsequent step, and drying in the drying step, and it is possible to significantly reduce the water content of the finally obtained dried rubber.

[Screw type extruder]
The screw type extrusion dryer 5 is an apparatus used for processing related to the extrusion drying step (dehydration step and drying step) in the synthetic rubber manufacturing method according to the present embodiment. Specifically, the screw type extrusion dryer 5 dehydrates the water-containing crumbs washed by the washing device 4 using a dehydration slit, and dries the dehydrated water-containing crumbs so as to obtain a dried rubber having a predetermined water content or less. It has become. Further, the screw type extrusion dryer 5 is configured to form the dried rubber obtained by the dehydration step and the drying step into a predetermined shape and discharge it.

Specifically, as will be described later with reference to FIG. 3, the screw type extruder 5 has a dehydration barrel portion 53 having a function as a dehydrator for dehydrating the hydrous crumb washed by the cleaning device 4. A drying barrel portion 54 having a function as a dryer for drying the hydrous crumb is provided, and a die portion 11 having a molding function for molding the hydrous crumb is further provided on the downstream side of the screw type extrusion dryer 5. Has been done.

Although the screw type extruder dryer 5 is used in the present embodiment, a centrifuge, a squeezer, or the like may be used as the dehydrator for performing the treatment related to the dehydration step, and the dryer for performing the treatment related to the drying step. A hot air dryer, a vacuum dryer, an expander dryer, a kneader type dryer, or the like may be used. Hereinafter, the screw type extruder is sometimes referred to as an extruder.

Hereinafter, the configuration of the screw type extruder 5 according to the present embodiment will be described with reference to FIG.

As shown in FIG. 2, the screw type extruder 5 is a biaxial screw type screw extruder having a pair of screws 59 in a barrel unit 51. The screw type extruder 5 has a drive unit 50 that rotationally drives a pair of screws 59 in the barrel unit 51. The drive unit 50 is attached to the upstream end of the barrel unit 51. Further, the screw type extruder 5 has a die portion 11 at the downstream end of the barrel unit 51.

The barrel unit 51 has a supply barrel portion 52, a dehydration barrel portion 53, and a dry barrel portion 54 from the upstream side to the downstream side.

The supply barrel portion 52 is composed of one supply barrel 52a.

The dehydration barrel portion 53 includes six dehydration barrels, that is, a first dehydration barrel 53a, a second dehydration barrel 53b, a third dehydration barrel 53c, a fourth dehydration barrel 53d, a fifth dehydration barrel 53e, and It is composed of a sixth dehydration barrel 53f. For example, the first dehydration barrel 53a and the third dehydration barrel 53c are set to remove water in liquid form (drainage), and the fifth dehydration barrel 53e is set to remove water in vapor form (exhaust vapor). Has been done.

The dry barrel portion 54 is composed of four dry barrels, that is, a first dry barrel 54a, a second dry barrel 54b, a third dry barrel 54c, and a fourth dry barrel 54d.

As described above, the barrel unit 51 is configured by connecting 11 divided barrels 52a, 53a to 53f, 54a to 54d from the upstream side to the downstream side.

The screw-type extruder 5 has a steam-type heating means that heats each of the barrels individually to heat the water-containing crumbs in each barrel to a predetermined temperature. The heating means has a corresponding number for each barrel. The heating means of the present embodiment has a configuration in which high-temperature steam is supplied from the steam supply means to the steam distribution jacket formed in each barrel, but the heating means is not limited to this. Further, the screw type extruder 5 has a temperature control means (not shown) that controls a set temperature of each heating means corresponding to each barrel.

The number of supply barrels, dehydration barrels, and drying barrels that constitute each barrel portion 52, 53, 54 in the barrel unit 51 is not limited to the mode shown in FIG. 2, and the acrylic rubber to be dried is used. The number can be set according to the water content of the water-containing crumb.

For example, the number of supply barrels installed in the supply barrel portion 52 is, for example, 1 to 3. Further, the number of dehydration barrels installed in the dehydration barrel portion 53 is preferably, for example, 2 to 10, and more preferably 3 to 6, because dehydration of the water-containing crumb of the adhesive acrylic rubber can be efficiently performed. Further, the number of dry barrels installed in the dry barrel portion 54 is preferably, for example, 2 to 10, and more preferably 3 to 8.

The pair of screws 59 in the barrel unit 51 are rotationally driven by a driving means such as a motor housed in the driving unit 50. The pair of screws 59 extend from the upstream side to the downstream side in the barrel unit 51, and by being rotationally driven, the water-containing crumbs supplied to the supply barrel portion 52 can be conveyed to the downstream side while being mixed. You can do it. The pair of screws 59 are of the biaxial meshing type in which the peaks and valleys are meshed with each other, whereby the dehydration efficiency and the drying efficiency of the hydrous crumb can be improved.

The pair of screws 59 of the present embodiment is of a type that rotates in the same direction from the viewpoint of self-cleaning performance, but is not limited to this, and the pair of screws 59 is of a type that rotates in different directions. May be good. The screw shape of the pair of screws 59 is appropriately determined in consideration of the compression / dehydration performance required for each of the barrel portions 52, 53, 54.

The supply barrel portion 52 shown in FIG. 2 is a region for supplying the water-containing crumb into the barrel unit 51. The supply barrel 52a of the supply barrel portion 52 has a feed port 55 for supplying a water-containing crumb into the barrel unit 51.

The dehydration barrel portion 53 is a region for separating and discharging a liquid (serum water) containing a coagulant or the like from the hydrous crumb. The first dehydration barrel 53a and the third dehydration barrel 53c constituting the dehydration barrel portion 53 have dehydration slits 56a and 56b for discharging the water content of the hydrous crumb to the outside, respectively. A plurality of the dehydration slits 56a and 56b are formed in the dehydration barrels 53a and 53c, respectively. Further, the fifth dehydration barrel 53e has a vent port 57c for discharging the water content of the hydrous crumb to the outside as steam.

The slit widths, that is, the openings of the dehydration slits 56a and 56b may be appropriately selected according to the conditions of use, and are usually 0.01 to 5 mm, so that the water-containing crumbs are less damaged and the water-containing crumbs are dehydrated. From the viewpoint of efficiency, it is preferably 0.1 to 1.0 mm, and more preferably 0.2 to 0.6 mm.

There are two types of removal of water from the water-containing crumbs in the dehydration barrels 53a to 53f of the dehydration barrel portion 53: a liquid removal from each dehydration slit and a vapor removal. In the dehydration barrel portion 53 of the present embodiment, the case where water is removed in liquid form is defined as wastewater, and the case where water is removed in vapor form is defined as exhaust steam.

The dehydration barrel portion 53 is suitable because the water content of the adhesive acrylic rubber can be efficiently reduced by combining drainage and exhaust steam. In the dehydration barrel portion 53, which of the dehydration barrels 53a to 53f is used for drainage or exhaust steam may be appropriately set according to the purpose of use, but the amount of ash in the acrylic rubber usually produced is usually produced. In order to reduce the amount of water, it is advisable to increase the number of dehydration barrels for draining. In the present embodiment, as shown in FIG. 2, drainage is performed in the first and third dehydration barrels 53a and 53c on the upstream side, and steam is discharged in the fifth dehydration barrel 53e. Further, for example, when the dehydration barrel portion 53 has four dehydration barrels, it is conceivable that, for example, drainage is performed by three dehydration barrels on the upstream side and steam is exhausted by one dehydration barrel on the downstream side. On the other hand, when reducing the water content, it is preferable to increase the number of dehydration barrels for exhausting steam.

The set temperature of the dehydration barrel portion 53 is usually in the range of 60 to 150 ° C., preferably 70 to 140 ° C., more preferably 80 to 130 ° C., and the set temperature of the dehydration barrel for squeezing out water in the drained state is usually 60 ° C. The temperature is usually 100 to 150 ° C, preferably 70 to 110 ° C, more preferably 80 to 100 ° C, and the set temperature of the dehydration barrel for reducing water content in the exhausted steam state is usually 100 to 150 ° C, preferably 105 to 140 ° C. It is preferably in the range of 110 to 130 ° C.

The drying barrel portion 54 is a region where the dehydrated hydrous crumb is dried under reduced pressure. The first dry barrel 54a, the second dry barrel 54b, the third dry barrel 54c, and the fourth dry barrel 54d, which constitute the dry barrel portion 54, are vent ports 58a, 58b, 58c for degassing. , 58d, respectively. Vent pipes (not shown) are connected to the vent ports 58a, 58b, 58c, and 58d, respectively.

Vacuum pumps (not shown) are connected to the ends of the vent pipes, and the operation of these vacuum pumps reduces the pressure inside the drying barrels 54a to 54d constituting the drying barrel portion 54 to a predetermined pressure. There is. The screw type extrusion dryer 5 has a pressure control means (not shown) that controls the operation of these vacuum pumps to control the degree of decompression in the drying barrels 54a to 54d constituting the drying barrel portion 54.

The degree of decompression in the dry barrel portion 54 may be appropriately selected, but as described above, it is usually set to 1 to 50 kPa, preferably 2 to 30 kPa, and more preferably 3 to 20 kPa. The set temperature in the drying barrel portion 54 may be appropriately selected, but as described above, it is usually set to 100 to 250 ° C, preferably 110 to 200 ° C, and more preferably 120 to 180 ° C.

In each of the dry barrels 54a to 54d constituting the dry barrel portion 54, the set temperatures in all the dry barrels 54a to 54d may be approximated or different, but on the upstream side (dehydrated barrel portion). It is preferable to set the temperature on the downstream side (die portion 11 side) to a higher temperature than the temperature on the 53 side) because the drying efficiency is improved.

The die portion 11 is a mold arranged at the downstream end of the barrel unit 51, and has a discharge port having a predetermined nozzle shape. The acrylic rubber dried by the drying barrel portion 54 is extruded into a shape corresponding to a predetermined nozzle shape by passing through the discharge port of the die portion 11. The acrylic rubber passing through the die portion 11 is formed into various shapes such as granular, columnar, round bar, and sheet depending on the nozzle shape of the die portion 11. In the present embodiment, the discharge port of the die portion 11 has a wide substantially rectangular shape, and acrylic rubber can be extruded into a sheet shape. A breaker plate or wire mesh may be provided between the screw 59 and the die portion 11.

According to the screw type extruder 5 according to the present embodiment, the water-containing crumb of the raw material acrylic rubber is extruded into the sheet-shaped synthetic rubber 15 as follows.

The water-containing crumb of acrylic rubber obtained through the cleaning step is supplied from the feed port 55 to the supply barrel portion 52. The water-containing crumb supplied to the supply barrel portion 52 is sent from the supply barrel portion 52 to the dehydration barrel portion 53 by the rotation of the pair of screws 59 in the barrel unit 51. In the dehydration barrel portion 53, as described above, the dehydration slits 56a and 56b provided in the first dehydration barrel 53a and the third dehydration barrel 53c, respectively, and the vents for exhaust steam provided in the fifth dehydration barrel 53e. Moisture contained in the water-containing crumb is drained and exhausted from the mouth 57c, and the water-containing crumb is dehydrated.

The water-containing crumb dehydrated by the dehydration barrel portion 53 is sent to the dry barrel portion 54 by the rotation of the pair of screws 59 in the barrel unit 51. The hydrous crumb sent to the dry barrel portion 54 is plasticized and mixed to form a melt, which generates heat and is carried to the downstream side while raising the temperature. Then, the water contained in the melt of the acrylic rubber is vaporized to become steam, and the steam is connected to the vent port 57c and the vent ports 58a, 58b, 58c, 58d for exhaust steam, respectively, which are not shown. It is discharged to the outside through.

As described above, the hydrous crumb is dried by passing through the dry barrel portion 54 to become a melt of acrylic rubber, and the acrylic rubber is supplied to the die portion 11 by the rotation of the pair of screws 59 in the barrel unit 51. It is extruded from the die portion 11 as a sheet-shaped synthetic rubber.

Here, an example of the operating conditions of the screw type extruder 5 according to the present embodiment will be given.

The rotation speed (N) of the pair of screws 59 in the barrel unit 51 may be appropriately selected according to various conditions, and is usually 10 to 1000 rpm, and the water content and gel amount of the acrylic rubber can be efficiently reduced. From the point of view, it is preferably 50 to 750 rpm, more preferably 100 to 500 rpm, and most preferably 120 to 300 rpm.

The extrusion amount (Q) of acrylic rubber is not particularly limited, but is usually 100 to 1500 kg / hr, preferably 300 to 1200 kg / hr, more preferably 400 to 1000 kg / hr, and 500 to 800 kg / hr. Most preferred.

The ratio (Q / N) of the extrusion amount (Q) of the acrylic rubber to the rotation speed (N) of the screw 59 is not particularly limited, but is usually 1 to 20, preferably 2 to 10, and more preferably 3. It is ~ 8, and 4 to 6 are particularly preferable.

Further, as shown in FIG. 3, immediately downstream of the screw type extruder 5 is a roller 12 as a side forming member extending in a direction substantially perpendicular to the sheet surface of the sheet-shaped synthetic rubber 15. It is provided. Both side surfaces of the sheet-shaped synthetic rubber 15 immediately after being extruded from the discharge port of the screw type extruder 5 are brought into contact with the roller 12 as a side forming member. As a result, the sheet-shaped synthetic rubber 15 immediately after being extruded by the screw-type extruder 5 can swell, collapse, or deform in the thickness direction near both side surfaces in a direction substantially perpendicular to the sheet surface. It is effectively suppressed by coming into contact with the roller 12 as the side forming member extending to the surface, and the unstable sheet shape is effectively suppressed. Therefore, it is possible to suppress variations in the product shape of the cut sheet-shaped synthetic rubber obtained in the subsequent process.

Specifically, on the downstream side of the discharge port 11b of the screw type extruder 5, a pair of rollers 12 as side forming members that come into contact with both side surfaces of the sheet-shaped synthetic rubber 15 are provided in the sheet width direction. It is provided at a distance. As a result, each of the pair of rollers 12 as the side forming member can form both side surfaces of the sheet-shaped synthetic rubber 15. In the present embodiment, a pair of rollers 12 are provided as the side forming member, but the number is not limited to two, and one or three or more rollers may be provided, and the number of pairs is one. It is not limited, and may be a plurality of pairs of rollers. Further, in the case of a plurality of pairs of rollers, it is preferable that the respective pairs of rollers are arranged so as to face each other with the sheet-shaped synthetic rubber 15 interposed therebetween, but they may be arranged alternately.

More specifically, the roller 12 as a side forming member is a roller that can rotate about a shaft 12a in a substantially vertical direction, and the side surfaces of the sheet-shaped synthetic rubber 15 extruded from the discharge port 11b come into contact with each other. It is designed to rotate passively. As a result, it is possible to prevent a load that resists the extrusion of the sheet-shaped synthetic rubber 15 from being generated, and to form the side surface of the sheet-shaped synthetic rubber 15 while maintaining a smooth pushing operation.

[Convey type cooling device]
The transport type cooling device 6 is a device used for a process related to a transport cooling step in the synthetic rubber manufacturing method according to the present embodiment. Specifically, the transport type cooling device 6 is a device used for cooling the dried rubber obtained by the screw type extrusion dryer 5. The transport type cooling device 6 according to the present embodiment blows cooling air from the cooling means 65 while transporting the sheet-shaped synthetic rubber 15 extruded from the die portion 11 of the screw type extruder 5 on the conveyor 61. As a result, it is cooled to a predetermined cooling temperature.

The cooling means 65 blows cooling air sent from a cooling air generating means (not shown) onto the surface of the sheet-shaped synthetic rubber 15 on the conveyor 61.

The length of the conveyor 61 and the cooling means 65 of the transport type cooling device 6 (the length of the portion where the cooling air can be blown) is not particularly limited, but is, for example, 2 to 100 m, preferably 5 to 50 m. Further, the transport speed of the sheet-shaped synthetic rubber 15 in the transport-type cooling device 6 is the length of the conveyor 61 and the cooling means 65, and the sheet-shaped synthetic rubber 15 discharged from the die portion 11 of the screw type extrusion dryer 5. It may be appropriately adjusted according to the discharge rate, the target cooling rate, the cooling time, and the like, but is, for example, 10 to 100 m / hr, more preferably 15 to 70 m / hr.

Further, the transport type cooling device 6 shown in FIG. 1 is used by being directly connected to the die portion 11 of the screw type extruder 5 shown in FIG. 2 or installed in the vicinity of the die portion 11.

The transport type cooling device 6 according to the present embodiment is an air cooling method, but is not limited to this, and various methods including a water spraying method of spraying water, a dipping method of immersing in water, and the like can be adopted. is there. Further, the dried rubber may be cooled by leaving it at room temperature.

[Cutting device]
The cutting device 7 is configured to perform a process related to a cutting step in the synthetic rubber manufacturing method according to the present embodiment. Specifically, the cutting device 7 is a device used for cutting the sheet-shaped synthetic rubber 15 after cooling. As shown in FIG. 1, the cutting device 7 according to the present embodiment cuts the tip end side portion of the sheet-shaped synthetic rubber 15 cooled to a predetermined cooling temperature by the transfer type cooling device 6 at a predetermined transfer position, and determines. It is configured to obtain a synthetic rubber 16 in the form of a cut sheet having a length.

[Veiling device]
The bale device 8 is a device used for processing the bale step in the synthetic rubber manufacturing method according to the present embodiment. Specifically, the bale-forming device 8 processes the dried rubber extruded from the screw-type extruder 5 to produce a bale which is a block.

As shown in FIG. 1, the bale device 8 according to the present embodiment manufactures a synthetic rubber bale 83, which is a block, by laminating, for example, cut sheet-shaped synthetic rubber 16 cut by the cutting device 7. Is configured to be possible. The bale device 8 manufactures a synthetic rubber bale 83 which is a block by sequentially laminating the synthetic rubber 16 in the form of a cut sheet cut by the cutting device 7 until it reaches a predetermined thickness or a predetermined weight. As a result, the synthetic rubber bale 83, which is easy to handle and has workability such as cutting, can be efficiently manufactured.

The weight and shape of the synthetic rubber bale 83 produced by the bale device 8 are not particularly limited, but for example, a substantially rectangular parallelepiped synthetic rubber bale 83 of about 20 kg is produced.

In the present embodiment, the adhesive rubber-like polymer is veiled as a crumb because it is extruded into a sheet by the screw type extruder 5 to sufficiently reduce the water content and then laminated to form a rubber bale. Not only is the ease of handling significantly improved, but also the mixing of impurities can be effectively suppressed, and the quality of the rubber product as a material can be improved.

When producing an acrylic rubber veil in which cut sheet-shaped acrylic rubber is laminated, it is preferable to laminate cut sheet-shaped acrylic rubber at, for example, 40 ° C. or higher. By laminating a cut sheet-like acrylic rubber at 40 ° C. or higher, good air release is realized by further cooling and compression by its own weight.

<Manufacturing method of synthetic rubber>
Next, a method of manufacturing synthetic rubber such as acrylic rubber by using the synthetic rubber manufacturing system 1 described above will be described.

FIG. 4 is a flowchart of a synthetic rubber manufacturing method according to an embodiment of the present invention. As shown in FIG. 4, the synthetic rubber manufacturing method according to the present embodiment includes an emulsion polymerization step S1, a solidification step S2, a cleaning step S3, an extrusion drying step S4, a transport cooling step S5, a cutting step S6, and a bale step S7. Includes. Hereinafter, each step will be described.

[Emulsion polymerization process]
In the emulsion polymerization step S1, in the emulsion polymerization apparatus, water and an emulsifier are mixed with a monomer component for forming a synthetic rubber, emulsified while appropriately stirring with a stirrer, and emulsion polymerization is carried out in the presence of a polymerization catalyst. This gives an emulsion polymerization solution (polymer latex).

[Coagulation process]
In the coagulation step S2, the polymer latex, the coagulant, and water are each supplied into the coagulation tank 30 at a set temperature and stirred by the stirrer 34 to generate a water-containing crumb. The set temperature (temperature of the coagulant aqueous solution) in the coagulation tank 30 is controlled by a temperature control unit so as to be usually in the range of 40 ° C. or higher, preferably 40 to 90 ° C., and more preferably 50 to 80 ° C.

Specifically, in the coagulation step S2, the polymer latex, the coagulant, and water are continuously supplied into the coagulation tank 30 at the respective supply temperatures and set supply amounts and flowed under stirring, and the set supply amount is set. And a hydrous crumb is generated in the coagulation tank 30 according to the strength of stirring, the supply temperature and the set temperature. In the present embodiment, the emulsion polymerization solution (polymer latex) is added to the coagulant aqueous solution that is agitated in the coagulation tank 30. The generated hydrous crumb overflows from the coagulation tank 30 together with warm water and is taken out of the coagulation tank 30.

The strength of stirring is determined by the number of rotations of the stirring blade 35 of the stirring device 34, the rotation speed, and the like. Strong stirring, that is, vigorous stirring is preferable because the particle size of the water-containing crumbs produced can be made small and uniform. If the stirring strength is excessively strong, a large crumb particle size and a small crumb particle size are formed, and if the stirring strength is excessively weak, it becomes difficult to control the coagulation reaction, which is not preferable. If the shape and particle size of the produced hydrous crumbs are uniform and integrated within a desired range, the removal of emulsifiers and coagulants during washing and dehydration is significantly improved, which is preferable.

In the present embodiment, in the coagulation step S2, the polymer latex, the coagulant, and water are continuously supplied into the coagulation tank 30 at the respective supply temperatures and set supply amounts while being stirred, and the set supply amount and the strength of stirring are performed. Moisture-containing crumbs can be continuously generated in the coagulation tank 30 according to the supply temperature and the set temperature, and the generated hydrous crumbs can be efficiently taken out of the coagulation tank 30 together with hot water by overflowing from the coagulation tank 30. it can.

Further, the supply water overflowing from the coagulation tank 30 is separated from the hydrous crumb, stored in a tank (not shown), and refluxed so as to be supplied to the coagulation tank 30 again. As a result, the water used for solidifying the polymer latex to form a water-containing crumb can be reused, and the amount of wastewater during the production of synthetic rubber can be suppressed. In this case, the overflowed hot water can be recirculated to the coagulation tank 30 side, but an overflowing hydrous crumb and a retention tank through which the hot water passes are provided, and the overflowed hot water flows out of the retention tank and is separated from the hydrous crumb. The hot water may be recirculated to the retention tank.

[Washing process]
In the washing step S3, the water-containing crumb and the washing water are supplied to the washing tank 40 at the set washing temperature, and the water-containing crumb is washed by stirring with the stirring device 44. The temperature of the washing water in the washing tank 40 is controlled by the temperature control unit so as to be usually in the range of 40 ° C. or higher, preferably 40 to 100 ° C., more preferably 50 to 90 ° C., and most preferably 60 to 80 ° C. To do.

Further, in the cleaning step S3, the washed water-containing crumb is overflowed from the washing tank 40 together with the washing water, taken out of the washing tank 40, drained by the drainer 49, and the water-containing crumb within a predetermined temperature range with respect to the set cleaning temperature is screwed. It is supplied to the material supply zone 150 of the mold extruder 5 (clam supply process). The temperature of the hydrous crumb supplied to the screw type extruder 5 is preferably 60 ° C. or higher. The temperature of the water-containing crumb is adjusted by directly heating the water-containing crumb using the heating device 41, but the temperature of the washing water may be adjusted, or the water-containing crumb may be directly heated using the heating device 41. It may be adjusted by heating, and the temperature of the washing water may be adjusted. By setting the set cleaning temperature to a temperature suitable for the cleaning and extrusion drying steps, for example, 40 ° C. or higher, the cleaning effect of the hydrous crumb can be enhanced and the efficiency of dehydration and extrusion drying can be enhanced.

[Extrusion drying process]
In the extrusion drying step S4, the water-containing crumb after cleaning is taken into the material supply zone 150 of the screw type extrusion dryer 5, compressed and dehydrated by the screw type extrusion dryer 5, and then the water content is evaporated by heating and kneading to contain a predetermined amount. Extrude synthetic rubber with less than the amount of water into a sheet.

Specifically, in the extrusion drying step S4, the water-containing crumb supplied to the material supply zone 150 is compression-dehydrated by the screw-type extrusion dryer 5, and then the water content is evaporated by heating and kneading to achieve a predetermined water content or less. The synthetic rubber of No. 1 is continuously extruded into a sheet having a thickness of, for example, 50 mm or less.

Further, the water separated from the hydrous crumb by the compression dehydration in the extrusion drying step S4 is supplied to a tank (not shown). As a result, water having a low coagulant concentration generated by dehydrating the hydrous crumb can be reused, and the amount of wastewater can be sufficiently suppressed.

Further, side surface molding in which both side surfaces of the sheet-shaped synthetic rubber 15 immediately after being extruded from the discharge port 11b of the screw type extruder 5 extend in a direction substantially perpendicular to the sheet surface of the sheet-shaped synthetic rubber 15. It is brought into contact with the roller 12 as a member. As a result, the sheet-shaped synthetic rubber 15 immediately after being extruded by the screw-type extruder 5 can swell, collapse, or deform in the thickness direction near both side surfaces in a direction substantially perpendicular to the sheet surface. It is effectively suppressed by coming into contact with the roller 12 as the side forming member extending to the surface, and the unstable sheet shape is effectively suppressed. Therefore, it is possible to suppress variations in the product shape of the cut sheet-shaped synthetic rubber 16 obtained in the subsequent process.

Specifically, on the downstream side of the discharge port 11b of the screw type extruder 5, a pair of rollers 12 as side forming members that come into contact with both side surfaces of the sheet-shaped synthetic rubber 15 are provided in the sheet width direction. Set apart. As a result, each of the pair of rollers 12 as the side forming member can form both side surfaces of the sheet-shaped synthetic rubber 15.

More specifically, the roller 12 as the side forming member is a roller that can rotate about the axis 12a in the substantially vertical direction, and the side surfaces of the sheet-shaped synthetic rubber 15 extruded from the discharge port 11b come into contact with each other. It rotates passively. As a result, it is possible to prevent a load that resists the extrusion of the sheet-shaped synthetic rubber 15 from being generated, and to form the side surface of the sheet-shaped synthetic rubber 15 while maintaining a smooth pushing operation.

[Transport cooling process]
In the transfer cooling step S5, the sheet-shaped synthetic rubber 15 extruded from the screw type extruder 5 is conveyed by the conveyor 61 of the transfer type cooling device 6 and cooled to a predetermined cooling temperature.

Specifically, in the transfer cooling step S5, the sheet-shaped synthetic rubber 15 extruded from the screw type extruder 5 is conveyed by the conveyor 61 of the transfer type cooling device 6, and the temperature at the time of extrusion is 60 ° C. or less. It is cooled at a cooling rate of 40 ° C./hr or more to a predetermined cooling temperature set between 20 ° C. and 50 ° C. As a result, the cut sheet-like cutting process on the tip end side of the sheet-shaped synthetic rubber 15 can be executed more stably.

By cooling the sheet-shaped synthetic rubber 15 at a cooling rate of 40 ° C./hr or more to a predetermined cooling temperature, scorch during processing of the sheet-shaped synthetic rubber 15 is effectively suppressed, and thus excellent processing stability can be achieved. Further, by setting the predetermined cooling temperature between 20 ° C. and 50 ° C., the sheet shape performed in the subsequent stage of the transport cooling step S5, for example, the cutting process of the sheet shape synthetic rubber on the tip side of the sheet shape. The synthetic rubber 15 can be easily and stably processed.

[Cutting process]
In the cutting step S6, the sheet-shaped synthetic rubber 15 cooled by the transport-type cooling device 6 is cut by the cutting device 7 to obtain a cut sheet-shaped synthetic rubber 16. Specifically, the tip end side portion of the sheet-shaped synthetic rubber 15 cooled to a predetermined cooling temperature of 60 ° C. or lower by the transport-type cooling device 6 is formed into a cut sheet of a predetermined length by the cutting device 7 at a predetermined transport position. Disconnect.

As a result, while the extrusion temperature in the extrusion drying step S4 is set relatively high to secure the extrusion amount, the cut sheet-like cutting process can be stably executed on the tip side of the sheet-like synthetic rubber 15. it can.

Further, the synthetic rubber bale 83 in which a plurality of cut sheets are substantially integrated is obtained by simply laminating the cut sheet-shaped synthetic rubbers 16 which are sufficiently cooled on the sheet to stabilize the shape. Since it can be easily manufactured, it is a manufacturing method capable of providing a rubber product having excellent shape stability.

[Veiling process]
In the bale step S7, dried rubber having a predetermined water content or less is veiled. Specifically, the cut sheet-shaped synthetic rubber 16 cut by the cutting device 7 is sequentially laminated and veiled in the bale device 8 until it reaches a predetermined thickness or a predetermined weight. As a result, the synthetic rubber bale 83, which is easy to handle and has workability such as cutting, can be efficiently manufactured. The bale can also be formed by putting the dried rubber obtained through the drying step into a baler and compressing it.

In the present embodiment, the synthetic rubber bale 83 is formed by extruding into a sheet shape by the screw type extruder 5 to sufficiently reduce the water content and then laminating the synthetic rubber bale 83. Therefore, the sticky rubber-like polymer is veiled as a crumb. Not only is the ease of handling significantly improved, but also the mixing of impurities can be effectively suppressed, and the quality of the rubber product as a material can be improved.

According to the method for producing synthetic rubber according to the present embodiment, synthetic rubber such as acrylic rubber suitable for various rubber products that require oil resistance, water resistance, storage stability, etc. at high temperatures can be efficiently produced. In particular, when an emulsion polymerization solution obtained by emulsion polymerization of a monomer component containing a reactive group-containing monomer in the presence of a divalent phosphoric acid emulsifier is coagulated with a magnesium salt, acrylic rubber having excellent storage stability and water resistance is obtained. Can be manufactured.

As described above, the present invention has the effect of effectively suppressing deformation of the extruded sheet-shaped synthetic rubber during extrusion and ensuring the shape stability of the product after extrusion. It is useful in all methods for producing synthetic rubber.

1 Synthetic rubber manufacturing system 3 Coagulation device 4 Cleaning device 5 Screw type extrusion dryer (extrusion dryer)
6 Conveyance type cooling device 7 Cutting device 8 Bale device 11 Die part 11a Nozzle 11b Discharge port 12 Roller (side surface forming member)
12a Axis 13 Roller 14 Roller Conveyor 15 Sheet-shaped Synthetic Rubber 16 Cut Sheet-shaped Synthetic Rubber 30 Coagulation Tank 40 Cleaning Tank 61 Conveyor 65 Cooling Means 70 Cutting Blade 83 Synthetic Rubber Veil 150 Material Supply Zone

Claims (3)

A coagulation step in which polymer latex, a coagulant, and water are each supplied into a coagulation tank at a set temperature and stirred to generate a hydrous crumb.
A cleaning step of supplying the water-containing crumb and cleaning water to a cleaning tank and stirring the water-containing crumb to clean the water-containing crumb.
The water-containing crumb after cleaning is supplied to the material supply zone of the extruder, and after compression and dehydration by the extruder, the moisture is evaporated by heating and kneading to extrude synthetic rubber having a predetermined moisture content or less into a sheet. Extrusion drying process and
It is a manufacturing method of synthetic rubber containing
It is characterized in that both side surfaces of the sheet-shaped synthetic rubber immediately after being extruded from the discharge port of the extruder is brought into contact with a side forming member extending in a direction substantially perpendicular to the sheet surface of the sheet-shaped synthetic rubber. A method for manufacturing synthetic rubber. The first aspect of the present invention is characterized in that, on the downstream side of the discharge port, a pair of side forming members that come into contact with each of both side surfaces of the sheet-shaped synthetic rubber are provided apart from each other in the sheet width direction. The method for producing a synthetic rubber according to the description. The side surface forming member is a roller that can rotate about an axis in a substantially vertical direction, and is characterized in that it passively rotates when the side surfaces of the sheet-shaped synthetic member extruded from the discharge port come into contact with each other. The method for producing a synthetic rubber according to claim 1 or 2.

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