JPH05133514A - Method for regenerating vulcanized rubber - Google Patents

Abstract

PURPOSE:To avoid environmental pollution by a method wherein vulcanized rubber is heated to desulfurization temperature by imparting microwave energy and heating air thereto to regenerate it, while gas of bad smell generated is burned to deodorize it and part of the processed gas is used as heating gas for desulfurization. CONSTITUTION:After selection 12 of the kind of waste vulcanized rubber in a raw material 11, the rubber is formed into powder in a crushing process 13 and rubber processing oil or regenerating agent is added to the powder of the rubber, which is mixed and adjusted 14 and then is heated to a specified temperature in a microwave heating process 15 to effect depolimerization reaction, wherein a burning type deodorizing device 31 is connected to discharge gas of bad smell produced by heat in a desulfurization precess from the process 15 to deodorize it so that part of the processed gas is regulated to a temperature close to the desulfurization temperature of the rubber to return it to the process 15 for reuse as heating air. The desulfurized rubber is passed through a cooling process 32 and a refining process 17 to be prepared as regenerated rubber 18 or passed through a mechanical heating means 33 and cooling process 34 to produce a regenerated rubber 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reusing vulcanized rubber so that it can be reused by utilizing microwave energy.

[0002]

2. Description of the Related Art As a conventional method for reusing vulcanized rubber, there are known a method of using finely pulverized unvulcanized rubber as a filler and a method of adding a regenerant and heating it to obtain a regenerated rubber.

However, the former has a high crushing cost for finely pulverizing it into a filler, and is often restricted in use. The latter method for producing regenerated rubber is to mix regenerated agent, softening agent or other chemicals with vulcanized rubber which has been crushed in advance, and add autoclave at 150 to 250 ° C.
After heat-treating for several hours, specifically 2 to 6 hours in a slag, it is scoured by a refine roll (finishing roll machine) and converted into a material having high plasticity.

However, the recycled rubber produced in this way usually has a bad odor characteristic of a regenerant, and its use is limited due to its contamination. Further, the heat treatment time, more specifically the depolymerization reaction time, is long, and it takes time and cost to treat a large amount, and there is a problem in terms of economy.

In view of the above circumstances, the applicant of the present invention has already proposed utility model registration No. 1642633 as a vulcanized rubber recycling apparatus using microwaves in order to solve such a problem. FIG. 6 is a block diagram showing a regeneration process in the vulcanized rubber recycling apparatus according to this utility model right. As shown in the figure, first, the type of waste vulcanized rubber in the raw material 11 is sorted by a sorting machine in the sorting step 12,
In the pulverizing step 13, the powder is pulverized by a pulverizer, and the rubber vulcanized oil or the regenerant is added to the powder vulcanized rubber in the blending and mixing step 14 as needed, and mixed. And
In the microwave heating step 15, the powder vulcanized rubber is heated to a predetermined temperature to cause a depolymerization reaction by utilizing microwave heating. More preferably, after the microwave heating, in the secondary heating step 16, the secondary heat treatment is performed by keeping the temperature for several minutes with hot air or the like. The reclaimed rubber product 18 is obtained by refining the depolymerized rubber thus obtained with a rolling machine in the refining step 17.

[0006]

In the vulcanized rubber recycling apparatus described above, a large amount of malodorous toxic gas is generated as the rubber temperature rises in the process up to desulfurization in the microwave heating step 15. This gas is a gas containing hydrogen sulfide, nitrogen, chlorine, aldehyde, etc. when the rubber polymer itself contained in the vulcanized rubber composition and the added chemicals such as oil vulcanization accelerator and foaming agent are decomposed. This is a phenomenon that cannot be avoided by the heating regeneration method.

For this reason, the microwave heating chamber provided in the microwave heating step 15 must discharge the generated gas to the outside in a timely manner. Since the inside of the microwave heating chamber is at normal pressure, the gas generated rapidly as the temperature of the vulcanized rubber rises creates a high-temperature, high-concentration atmosphere. When the microwave is irradiated in such an atmosphere, the insulation in the microwave heating chamber is deteriorated, and thus sparks due to electric discharge easily occur,
Eventually, the gas ignites and explodes, which is extremely dangerous and a serious problem for industrial equipment.

In order to prevent such a danger, the generated gas must be discharged to the outside in a timely manner. However, the generated gas has a bad odor and is sometimes toxic, so from the viewpoint of pollution, it can be directly exposed to the outside air. It is a big problem to release it.

FIG. 7 shows a temperature rise curve 19 for the rubber temperature. As shown in this figure, the vulcanized rubber that is heated linearly up to around 140 ° C. by the input of microwave energy (indicated by reference numeral 20) shows that from this temperature, oil and chemicals contained in the vulcanized rubber are evaporated. A large amount of malodorous gas (indicated by reference numeral 21) is generated until the desulfurization temperature is reached. At this time, the latent heat of vaporization lowers the rubber temperature, so that the temperature rise becomes worse.

Further, since the exhaust is repeated to prevent the gas explosion, the heat radiation of the rubber temperature is further increased, and it takes a long time and a lot of microwave energy to reach the target desulfurization temperature, which is economically economical. The problem is big. The exhaust fan exhausts air continuously or intermittently according to the time chart indicated by reference numeral 22.

In view of the above-mentioned circumstances, the present invention is capable of depolymerizing the unvulcanized rubber with high efficiency by simultaneously heating microwave energy and heated air, and a large amount of malodorous gas generated in the desulfurization process. It is an object of the present invention to develop a method of obtaining a pollution-free industrially extremely advantageous reclaimed rubber which is capable of deodorizing and treating a part of the deodorized gas as heating energy.

[0012]

In order to achieve the above object, in the present invention, as a first invention, microwave energy and heated air are simultaneously applied to heat a vulcanized rubber to a desulfurization temperature to regenerate it. In the rubber recycling method, the malodorous gas generated by heating during this desulfurization process is brought into direct contact with the flame of the combustion type deodorizing device to burn the malodorous gas for deodorizing treatment, and a part of the treated gas is desulfurized. A method for regenerating vulcanized rubber, characterized in that the vulcanized rubber is adjusted to or near the optimum desulfurization temperature of the vulcanized rubber and used as heated air required for desulfurization, and other process gas is exhausted to the outside air. To propose.

In a second aspect of the invention, a vulcanized rubber is supplied with microwave energy and heated air to be in a partially decomposed and polymerized state, and then the rubber is machined at a high speed rotary kneader or an extruder equipped with a shear head. A method for regenerating a vulcanized rubber according to the first invention is characterized in that it is heated by a dynamic heat generating means to accelerate desulfurization.

[0014]

According to the first aspect of the present invention, microwave energy and heated air are simultaneously applied to the vulcanized rubber, and the oil and chemicals contained in the vulcanized rubber material are decomposed before the desulfurization temperature is reached from room temperature. It is possible to raise the temperature linearly in a short time without causing the temperature drop of the vaporized gas and the temperature drop caused by the exhaust. That is, from the viewpoint of pollution, a large amount of malodorous gas generated during the desulfurization process is deodorized by a combustion type deodorizing device, and a part of the treated gas is temperature-controlled near the optimum desulfurization temperature of the vulcanized rubber to be desulfurized. Use the heated air required for desulfurization. For this reason, since the deodorizing gas is constantly reused, the rubber temperature rises linearly without a temperature drop, which is economical in terms of efficiency.Also, the remaining gas is smoked to the outside but is deodorized. Therefore, it can be said that it is an excellent rubber recycling method in terms of pollution.

In the above-mentioned first invention, when the vulcanized rubber reaches the desulfurization temperature by the action of microwave energy and heated air, the carbon-carbon and sulfur-carbon bonds are broken,
A part of the rubber polymer molecule is also cut into a completely depolymerized state. On the other hand, in the second invention, the rubber in the state of partial decomposition polymerization during the progress of depolymerization in which desulfurization has not yet been sufficiently performed (hereinafter referred to as rubber in the partial decomposition polymerization state) is immediately provided with a mechanical heating means. In addition, the heat generated is utilized to accelerate desulfurization. That is, the mechanical heat generating means, for example, a kneading roll machine with a groove, a high-speed rotary kneading machine, an extruder, shearing heat to the rubber in the partially decomposed and polymerized state by a shear-head, kneading and extruding, It is designed to accelerate desulfurization sufficiently by generating heat. In addition, this method can also serve to refine the recycled rubber and shape it.

[0016]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing a reproducing process according to the present invention, and parts corresponding to those of the conventional reproducing process shown in FIG. 6 are designated by the same reference numerals. The crushed rubber is mixed in the mixing and mixing step 14 by adding a rubber processing oil or a regenerant, if necessary, depending on the kind of the rubber. The rubber which does not require this step is directly put into the microwave heating step 15 while being crushed.

A combustion type deodorizing device 31 is connected to the microwave heating process 15, and the malodorous gas generated by heating during the desulfurization process is discharged from the microwave heating process 15 and deodorized by the deodorizing device 31. A part of the treated gas is adjusted to near the desulfurization temperature of the vulcanized rubber of interest, returned to the microwave heating step 15, and reused as heated air.

Further, the remaining processing gas is deodorized and smoked to the outside air to make it pollution-free. Since the treated gas (exhaust air) immediately after the deodorizing process has a considerably high temperature, it is used as heat energy for returning to the crushed rubber after the pre-process, for example, the mixing and mixing process 14 or the crushing process 13 to preheat it as shown in FIG. be able to. The preheating temperature of the rubber in this case is at least within a range where a foul-smelling gas is not generated due to the heating temperature rise (preferably 140 ° C. or lower), and even if the rubber is directly discharged to the outside through the same path as the smoke exhausted from the deodorizing device 31, it will cause pollution. There is no problem.

Preheating the crushed rubber leads to energy saving in the microwave heating step 15 and is an economical means. When exhausting air as it is from the deodorizing device 31 without preheating the rubber, the exhaust air is at a high temperature, so fresh air is taken in by a blower (not shown) to mix and lower the temperature, or in an atmosphere where water is sprinkled. It is preferable to pass the gas to lower the temperature before exhausting the smoke.

In this way, depending on the kind of rubber to be treated in the microwave heating step 15, it is 190 ° C to 350 ° C.
It is possible to desulfurize by linearly heating to a temperature of about 0 ° C. to cause a depolymerization reaction in a short time. The desulfurized rubber undergoes a cooling step 32 and a refining step 17 to produce a recycled rubber 18, or a mechanical heating means 33 and a cooling step 34 to produce a recycled rubber 18.

When the depolymerized rubber is heated to the desulfurization temperature and cooled, oxidative deterioration gradually progresses due to the heat accumulated in the rubber itself, self-heating occurs, and in some cases carbonization or ignition due to overheating is caused. To prevent
This is also a necessary process because it suppresses the generation of malodorous gas.
In the cooling steps 32 and 34, rapid cooling is performed by the heat of vaporization of an inert liquid such as water, freon, liquefied carbon dioxide, or the like, or by heat conduction by circulating a refrigerant.

As a cooling means, the applicant of the present invention has already proposed Japanese Patent No. 1419246 as a method for regenerating vulcanized rubber, and the desulfurized rubber is cooled by addition of water to a temperature at which oxidative deterioration does not proceed. It is effective in terms of speed, uniformity, workability and facility cost, and running cost to cool the amount of water to a range that does not cause a change in the weight of the desulfurized rubber and a decrease in physical properties, preferably 100 ° C. or higher. .. The rubber after cooling may be refined and refined by a refining roll (finishing roll machine) in the refining step 17 if necessary.

Further, in the method described in claim 2, in the microwave heating step 15, vulcanized rubber desulfurization is started by simultaneous heating of microwave energy and heated air, and the rubber which is in a partially decomposed and polymerized state is mechanically treated. The heat generating means 33 applies shear heat and frictional heat to generate heat to accelerate depolymerization. This measure allows heat to be generated effectively and efficiently. For example, a kneading machine with a grooved roll, a high-speed rotary kneading machine capable of sufficiently giving a shear, and an extruder equipped with a shear head can be used. Furthermore, the above-mentioned purification step 1
Since the same refining function as that of No. 7 can be provided, a good recycled rubber 18 can be manufactured.

Next, a regenerating apparatus for carrying out the method for regenerating vulcanized rubber according to the present invention is shown in FIG. 2 and FIG. 3, which illustrates a regenerating apparatus for embodying the technical idea of the present invention. However, the material, shape, structure, and arrangement of the mechanical parts are not limited to the following structures. Various modifications can be made to this reproducing apparatus within the scope of the claims of the present invention.

FIG. 2 is a simplified front view of the heating device, and FIG. 3 is a simplified side view of the heating device. In these figures, reference numeral 41 denotes a microwave heating chamber, whose bottom portion has a semi-cylindrical shape, and a U-shaped bottom portion 42 is provided with a screw 44 and a screw for transfer which are rotated by driving a motor 43. The fins 45 are provided for each constant pitch of the screw to stir the object to be heated on the fins to mix and stir. The ground vulcanized rubber 46, which is an object to be heated, is continuously dropped from the raw material tank 47 into the microwave heating chamber 41 by the supply feeder 48, and the rotating transfer screw 44 and the rotating transfer screw 44 are provided. The blade 45 attached to the screw moves to the outlet while mixing and stirring, and the mixture is discharged by the rotary valve 49 provided at the outlet.

While being mixed, agitated and transferred, the vulcanized rubber 46 simultaneously receives microwave energy and heated air and is heated to the desulfurization temperature. Waveguide 5 oscillated by oscillator 50
It is irradiated from the irradiation opening at the tip of 1. The irradiation port is made of a material such as Teflon ceramic or quartz glass.
A rule plate 52 is provided. An inspection door 53 is provided above the microwave heating chamber 41.

The heated air is sent to the microwave heating chamber 41 after the deodorizing process by the combustion type deodorizing device 54.
The fuel of No. 4 uses heavy oil, kerosene and gas such as LPG and LNG, and is supplied through a piping system such as a control valve 55.

On the other hand, the air for combustion is mixed with fuel by the combustion air feed blower 56 after passing through the air-control valve 57 and ignited by the combustion burner 58, and a flame 59 is emitted. To burn. At this time, the combustion temperature atmosphere in the deodorizing furnace is set to a set temperature of 5 by the signal of the temperature sensor 60.
The temperature is adjusted to be 00 ° C or higher (preferably 550 to 750 ° C). Since the inner wall of the deodorizing device 54 has such a high temperature, it is made of a refractory material such as refractory bricks.

The malodorous gas generated from the microwave heating chamber 41 is sucked by the exhaust fan 61, and is brought into direct contact with the flame 59 of the deodorizing device 41 that burns at a high temperature of 500 ° C. or more to burn instantly. This contact time is preferably set in the range of 0.3 to 1 second so that oil, hydrogen sulfide, nitrogen, chlorine, aldehyde, etc. contained in the malodorous gas can be reliably burned and decomposed. Hot gas (hot air) immediately after combustion
Is mixed by a fan 62 that supplies fresh air into the room and a damper valve 63 that adjusts the amount of the air to lower the temperature. However, the temperature in this case must be near the desulfurization temperature of the vulcanized rubber or higher, which is the target temperature for blowing air to the microwave heating chamber 41.

The heated air that has been deodorized in this way and has a temperature higher than the desulfurization temperature is partly released to the outside air through the exhaust duct 64.
In some cases, Ox and CO ₂ may be treated, or water may be passed through an atmosphere in which water is sprinkled to reduce the temperature and then smoke is discharged.

Further, as described above, if this heated air is used as preheating energy for raising the temperature of the rubber immediately after the rubber crushing manufacturing step 13 (just before entering the microwave heating chamber 41), it is economical from the viewpoint of energy saving. Target. Further, the heated air that does not emit smoke is operated near the desulfurization temperature (180 ° C. to 350 ° C.) of the vulcanized rubber set in advance by the function of the temperature sensor 67 and the control valve 66 that moves according to the signal via the blower branch duct 65. ) And is supplied to the microwave heating chamber 41. In this way, when viewed from the microwave heating chamber 41, the path of the heated air is circulated in the cycle of supply-exhaust-deodorization-supply.

In order to control whether or not the temperature of the depolymerized rubber that has been heated to the desulfurization temperature by simultaneously receiving microwave energy and heated air in the microwave heating chamber 41 is at an appropriate temperature (appropriate desulfurization). In addition, it can be detected by the temperature sensor 69 provided with a filter 68 provided with a radio wave leakage countermeasure and an air purge filter near the rubber outlet. Further, the measurement signal and the preset temperature are signal-processed by the comparison calculation unit 70, and the microwave output is automatically controlled so that the rubber temperature can be adjusted so that the reproduction condition is always suitable.

Thus, the vulcanized rubber 46 which has been desulfurized is immediately cooled with water in the cooling step 32 (FIG. 1) as described above. If necessary, a reclaimed rubber product 18 is obtained via a step 17 of refining and refining with a refine roll (finishing roll machine).

Next, FIG. 4 shows a shear-head extruder as a mechanical heating means for carrying out the regeneration method described in claim 2 of the claims. Note that FIG. 5A is a vertical cross-sectional view of a heat-generating tip portion of the extruder, and FIG. 5B is a vertical cross-sectional view of a screw-heat generating portion of the extruder.
The cylinder 71 comprises a heat generating tip 72 and a supply port 73 for supplying crushed rubber. The tip 72 has a large number of recessed grooves 74 with a shallow depth, and further circulates to control the temperature of this portion. The structure is provided with a hole 75 through which hot water and oil flow. Inside the cylinder 71, the screw
76 is provided, and the cylinder heat generating tip 7 is provided on the tip side thereof.
The heat generating portion 77 is arranged at a position corresponding to No. 2, and the surface thereof is provided with the ridge portion 78 having a low height in order to efficiently cause shear and friction in the rubber. In addition, the screw
76 is rotated by a motor 80 via a reduction gear 79.

In the microwave heating step 15, desulfurization is started by the simultaneous overheating of microwave energy and heated air, and the pulverized rubber which is in the partial decomposition polymerization state and undergoes plasticization is continuously supplied from the supply port 73. The rotating screw 76 is pushed into the tip heat generating portion 77 while being sequentially fed under pressure. At the tip portion, the gap 8 between the tip heating portion 72 having a large number of concave grooves 74 and the screw tip portion 8
1, the screw head ridges 78 that rotate and fill up with 1 also synergistically generate shear heat and friction heat with great momentum.
The rubber itself generates heat and the depolymerization reaction proceeds, and the sufficiently plasticized desulfurized rubber is continuously discharged from the heat generating tip portion 72 in the shape of a twisted string. The desulfurized rubber that is continuously discharged is immediately cooled in the cooling step 34 described above to become the recycled rubber product 18.

While the plasticization is promoted by the mechanical heat generating means to accelerate the desulfurization, that is, the rubber and cylinder 71 between the outlet of the microwave heating chamber 41 (FIG. 2) and the supply port 73 of the cylinder 71. The temperature of the rubber released from the tip of is high, and a large amount of malodorous gas is generated. Therefore, these parts are sufficiently exhausted to be passed to the combustion type deodorizing device 54 used in the microwave heating chamber 41 for deodorizing treatment. This is a more effective means for carrying out the system of the present invention in a good working environment. (Not shown in FIG. 1)

[0037]

As described above, the method for regenerating vulcanized rubber according to the present invention is a method in which microwave energy and heated air are simultaneously given to linearly raise the temperature to the desulfurization temperature to accelerate the depolymerization reaction. Therefore, it becomes possible to realize a continuous shortening of time and systematization, which was impossible in the past.

Further, since a large amount of malodorous gas generated during desulfurization is constantly discharged, even if spark is generated due to microwave discharge, there is no danger of igniting the generated gas and exploding. In addition, since a large amount of odorous gas that is emitted is deodorized, the problem is solved from the viewpoint of pollution due to smoke exhaust in the working environment. Energy is saved because a part of the exhaust gas deodorized by the deodorizer is reused as energy for heating and regeneration.
Excellent in shortening the time.

Due to the short-time desulfurization treatment, the physical properties of the regenerated rubber obtained are such that the size of the rubber polymer molecule before vulcanization is the same as in the conventional long-term depolymerization reaction method (autoclave method). A good recycled rubber can be obtained without being cut extremely smaller than the original one.

The basic idea of the present invention is that since a regenerating agent, a softening agent and the like are not mixed as in the conventional regenerating method which is a depolymerization reaction by heat, the problem of generation of offensive odor from the regenerated rubber and contamination. There is no. However, with special rubber materials, there is an exception to add a slight softening agent when the oxidation reaction progresses during desulfurization and the rubber tends to harden and carbonize (rubber material having a very narrow temperature range for plasticizing).

Desulfurization state (depolymerization state) of recycled rubber products,
That is, the desulfurization temperature condition can be easily adjusted by arbitrarily and immediately adjusting the microwave energy and the heating air temperature to be applied.

Further, according to the method of the present invention, the vulcanized rubber is heated, and a mechanical heat generating means is applied to the partially decomposed and polymerized rubber (rubber in the middle of plasticization) in which desulfurization has not been completed sufficiently. It is also possible to combine the steps of refining to sufficiently desulfurize and to form the shape of recycled rubber. In this case, it is possible to reduce the temperature rising condition of the rubber due to the microwave energy and the heated air.

As described above, the method for regenerating a heated rubber according to the present invention is a method for regenerating a rubber which is safe, has an excellent working environment, is economical, has high productivity, and can produce a good regenerated rubber. is there.

[Brief description of drawings]

FIG. 1 is a block diagram of a reproducing method according to an embodiment of the present invention.

FIG. 2 is a simplified front view showing a vulcanized rubber recycling apparatus for carrying out the recycling method of the present invention.

FIG. 3 is a simplified side view of the vulcanized rubber recycling apparatus.

FIG. 4 is a schematic vertical sectional side view of a shear-head extruder shown as an example of a mechanical heating means.

FIG. 5 (A) is a vertical cross-sectional view of a heat-generating tip portion in a shear-head extruder. Fig. 5B shows the share-
It is a longitudinal cross-sectional view of a screw-heat generating portion in the head extruder.

FIG. 6 is a block diagram showing a regeneration process of a vulcanized rubber recycling apparatus shown as a conventional example.

FIG. 7 is a diagram for explaining a temperature rising state of vulcanized rubber.

[Explanation of symbols]

 11 Raw Material 12 Sorting Step 13 Grinding Step 14 Mixing and Mixing Step 15 Microwave Heating Step 17 Refining Step 18 Reclaimed Rubber Product 31 Deodorizing Device 32 Cooling Step 33 Mechanical Heating Means 34 Cooling Step

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Claims (2)

[Claims] 1. A method of regenerating a rubber in which microwave energy and heated air are simultaneously applied to heat a vulcanized rubber to a desulfurization temperature to regenerate it, and a malodorous gas generated by heating during the desulfurization step is burned and deodorized. Direct contact with the flame of the device,
The odorous gas is burned to perform deodorizing treatment, and a part of the treated gas is adjusted to at or near the optimum desulfurization temperature of the vulcanized rubber to be desulfurized and used as heated air required for desulfurization. The method for recycling vulcanized rubber is characterized in that the treated gas is discharged to the outside air. 2. A vulcanized rubber is supplied with microwave energy and heated air to be in a partial decomposition polymerization state, and then this rubber is subjected to a mechanical heating means such as a high-speed rotary kneading machine or an extruder equipped with a shear head. The method for regenerating vulcanized rubber according to claim 1, wherein heating is performed to accelerate desulfurization.